Journal articles: 'Low-MAC'

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Banari, Ehsan, Sayyed Majid Mazinani, and Iman Sariri Ajili. "An Energy-Efficient and Low-Latency MAC Protocol in Smart Grid (SG-MAC)." Journal of Clean Energy Technologies 3, no. 4 (2015): 242–46. http://dx.doi.org/10.7763/jocet.2015.v3.202.

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Malina, Judith. "Remembering Jackson Mac Low." PAJ: A Journal of Performance and Art 27, no. 2 (2005): 76–78. http://dx.doi.org/10.1162/1520281053850910.

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Zayani, Hafedh. "Low-Traffic Aware Hybrid MAC (LTH-MAC) Protocol for Wireless Sensor Networks." International Journal on Information Technologies and Security 16, no. 2 (2024): 3–14. http://dx.doi.org/10.59035/shzm1009.

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This paper proposes LTH-MAC (Low-Traffic Aware Hybrid MAC), a novel MAC protocol designed to improve energy efficiency and message delivery reliability in Wireless Sensor Networks (WSNs). LTH-MAC achieves this through innovative techniques like flexible timeslots, channel selection, collision-avoiding, parallel transmissions, and efficient backoff schemes. These optimizations lead to reduced idle listening, minimized collisions, and simplified synchronization. Simulations using OPNET environment demonstrate that LTH-MAC significantly reduces energy consumption, especially under light traffic loads. Additionally, LTH-MAC provides lower end-to-end latency and higher message delivery reliability compared to ECoMAC. These advancements position LTH-MAC as a compelling solution for WSN applications demanding efficient and reliable communication.

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Sessler, Daniel I., Jeffrey C. Sigl, Scott D. Kelley, et al. "Hospital Stay and Mortality Are Increased in Patients Having a “Triple Low” of Low Blood Pressure, Low Bispectral Index, and Low Minimum Alveolar Concentration of Volatile Anesthesia." Anesthesiology 116, no. 6 (2012): 1195–203. http://dx.doi.org/10.1097/aln.0b013e31825683dc.

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Background Low mean arterial pressure (MAP) and deep hypnosis have been associated with complications and mortality. The normal response to high minimum alveolar concentration (MAC) fraction of anesthetics is hypotension and low Bispectral Index (BIS) scores. Low MAP and/or BIS at lower MAC fractions may represent anesthetic sensitivity. The authors sought to characterize the effect of the triple low state (low MAP and low BIS during a low MAC fraction) on duration of hospitalization and 30-day all-cause mortality. Methods Mean intraoperative MAP, BIS, and MAC were determined for 24,120 noncardiac surgery patients at the Cleveland Clinic, Cleveland, Ohio. The hazard ratios associated with combinations of MAP, BIS, and MAC values greater or less than a reference value were determined. The authors also evaluated the association between cumulative triple low minutes, and excess length-of-stay and 30-day mortality. Results Means (±SD) defining the reference, low, and high states were 87 ± 5 mmHg (MAP), 46 ± 4 (BIS), and 0.56 ± 0.11 (MAC). Triple lows were associated with prolonged length of stay (hazard ratio 1.5, 95% CI 1.3-1.7). Thirty-day mortality was doubled in double low combinations and quadrupled in the triple low group. Triple low duration ≥60 min quadrupled 30-day mortality compared with ≤15 min. Excess length of stay increased progressively from ≤15 min to ≥60 min of triple low. Conclusions The occurrence of low MAP during low MAC fraction was a strong and highly significant predictor for mortality. When these occurrences were combined with low BIS, mortality risk was even greater. The values defining the triple low state were well within the range that many anesthesiologists tolerate routinely.

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Khan, Bilal Muhammad, and Rabia Bilal. "Mobility Adaptive Energy Efficient and Low Latency MAC for Wireless Sensor Networks." International Journal of Handheld Computing Research 4, no. 2 (2013): 40–54. http://dx.doi.org/10.4018/jhcr.2013040103.

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In this paper a high throughput, low latency, mobility adaptive and energy efficient medium access protocol (MAC) called Mobility Adaptive (MA) for wireless sensor networks. MA-MAC ensures that transmissions incur no collisions, and allows nodes to undergo sleep mode whenever they are not transmitting or receiving. It uses delay allocation scheme based on traffic priority at each node and avoids allocating same backoff delay for more than one node unless they are in separate clusters. It also allows nodes to determine when they can switch to sleep mode during operation. MA-MAC for mobile nodes provides fast association between the mobile node and the cluster coordinator. The proposed MAC performs well in both static and mobile scenarios, which shows its significance over existing MAC protocols proposed for mobile applications. The performance of MA-MAC is evaluated through extensive simulation, analysis and comparison with other mobility aware MAC protocols. The results show that MA-MAC outperforms significantly the existing CSMA/CA, Sensor Mac (S-MAC), Mobile MAC (MOB-MAC), Mobility aware Delay sensitive MAC (MD-MAC) and Dynamic Sensor MAC (DS-MAC) protocols including throughput, latency and energy consumption.

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Marín, I., J. Arias, E. Arceredillo, A. Zuloaga, I. Losada, and J. Mabe. "LL-MAC: A low latency MAC protocol for wireless self-organised networks." Microprocessors and Microsystems 32, no. 4 (2008): 197–209. http://dx.doi.org/10.1016/j.micpro.2007.10.003.

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Kim, Seong Cheol. "Low-Latency MAC (LL-MAC) Protocol for a Multi-Hop Wireless Sensor Networks." Applied Mechanics and Materials 536-537 (April 2014): 364–67. http://dx.doi.org/10.4028/www.scientific.net/amm.536-537.364.

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In this paper, we present a new MAC protocol, called Low-Latency MAC (LL-MAC) protocol for muti-hop Wireless Sensor Networks. The LL-MAC is designed for the object tracking applications such as animal invasion, flight detection and wild animal detection. In these applications, the object appearance event does not occur frequently. But when an event occurs, many measured data by sensor nodes should be sent to a sink node as soon as possible. LL-MAC uses duty cycling contention-based MAC protocol. The operational cycle is divided into four periods: Sync, carrier sensing, Data, and Sleep. The Sleep period will be increased to send more packets by sender node when a target object appearance occurs. And a status bit in PION packet is used to indicate target appearance by the sender node. If this status bit is set to 1, all nodes know an object appearance and adjust their Sleep period to two times longer. After sending data packets, the sender node goes into sleep mode and wake ups again in two times slot times to send more data. Results showed that our LL-MAC protocol outperformed other protocols in terms of data packet delivery delay.

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Son, Vo Que, and Tran Truong Son. "Enhancement of Asynchronous MAC Protocol in Wireless Sensor Networks for Smart Monitoring Applications." Journal of Science and Technology: Issue on Information and Communications Technology 3, no. 1 (2017): 51. http://dx.doi.org/10.31130/jst.2017.38.

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Up to now, many research works have been focusing on designs in MAC layer of Wireless Sensor Networks (WSNs) to target high throughput, low latency and solving the problem of idle listening. In this paper, an enhancement of Low-power asynchronous protocol for MAC layer, namely E-MAC, is proposed to target a long lifetime of sensor nodes working 6LoWPAN/IPv6 networks. Moreover, the E-MAC protocol is implemented on TI low-power platforms to verify the efficiency of the proposed design. Several parameters such as energy consumption, latency and packet delivery ratio are simulated and measured in a real monitoring test-bed to show the better performance in comparison with other popular MAC protocols.

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Bauwens, Jan, Nicola Macoir, Spilios Giannoulis, Ingrid Moerman, and Eli De Poorter. "UWB-MAC: MAC protocol for UWB localization using ultra-low power anchor nodes." Ad Hoc Networks 123 (December 2021): 102637. http://dx.doi.org/10.1016/j.adhoc.2021.102637.

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Jeon, Jun-Heon, and Seong-Cheol Kim. "A Low-Delay MAC(LD-MAC) protocol in Multi-Hop Wireless Sensor Networks." Journal of the Korea Institute of Information and Communication Engineering 18, no. 2 (2014): 452–58. http://dx.doi.org/10.6109/jkiice.2014.18.2.452.

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Al-Sulaifanie, Adnan Ismail, Subir Biswas, and Bayez Khorsheed Al-Sulaifanie. "AH-MAC: Adaptive Hierarchical MAC Protocol for Low-Rate Wireless Sensor Network Applications." Journal of Sensors 2017 (2017): 1–15. http://dx.doi.org/10.1155/2017/8105954.

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This paper proposes an adaptive hierarchical MAC protocol (AH-MAC) with cross-layer optimization for low-rate and large-scale wireless sensor networks. The main goal of the proposed protocol is to combine the strengths of LEACH and IEEE 802.15.4 while offsetting their weaknesses. The predetermined cluster heads are supported with an energy harvesting circuit, while the normal nodes are battery-operated. To prolong the network’s operational lifetime, the proposed protocol transfers most of the network’s activities to the cluster heads while minimizing the node’s activity. Some of the main features of this protocol include energy efficiency, self-configurability, scalability, and self-healing. The simulation results showed great improvement of the AH-MAC over LEACH protocol in terms of energy consumption and throughput. AH-MAC consumes eight times less energy while improving throughput via acknowledgment support.

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Ullah, Niamat, M. Sanaullah Chowdhury, Mosaddique Al Ameen, and Kyung Sup Kwak. "Energy Efficient MAC Protocol for Low-Energy Critical Infrastructure Monitoring Networks Using Wakeup Radio." International Journal of Distributed Sensor Networks 8, no. 4 (2012): 504946. http://dx.doi.org/10.1155/2012/504946.

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Critical infrastructure monitoring applications are rapidly increasing. Application requirements include reliable data transfer, energy efficiency, and long deployment lifetime. These applications must also be able to operate in an extremely low-cost communication environment in order to be attractive to potential users. A low rate wireless personal area network can help control and manage the operations of such applications. In this paper, we present a medium access control (MAC) protocol for low-energy critical infrastructure monitoring (LECIM) applications. The proposed MAC protocol is based on a framed slotted aloha multiple access schemes. For downlink communication, we use a wakeup radio approach to avoid complex bookkeeping associated with the traditional MAC protocols. Analytical expressions for power consumption and delay are derived to analyze and compare the performance of our proposed protocol with the existing well-known T-MAC, B-MAC, X-MAC, ZigBee, and WiseMAC protocols. It is shown that our proposed protocol outperforms all the other protocols in terms of power consumption and delay.

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Basha, Mathiana, and Aravind Shanmugam. "Measurement mid arm circumference and study its correlation with the birth weight of the babies." International Journal of Contemporary Pediatrics 9, no. 11 (2022): 1034. http://dx.doi.org/10.18203/2349-3291.ijcp20222762.

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Background: To know the correlation between birth weight and mid arm circumference (MAC). To test the sensitivity and specificity of cut off limits of MAC for the identification of low-birth-weight babies <2000 gm and <2500 gm.Methods: In this observational study, 300 children were enrolled. Birth weight was measured using electronic weighing scale of accuracy 10 grams within 24 hours of life. Right MAC was measured using non-stretchable tap to the nearest of 0.1 cm at the midpoint between tip of olecranon process of ulna and the acromian process of scapula. Data was analyzed using SPSS. Different cut offs for MAC and their sensitivity, specificity to identify LBW babies <2.5 kg was analyzed through ROC. The study was approved by the institutional ethics committee.Results: MAC highly correlated with weight (p<0.001). A MAC of <10 cm, predicts a birth weight of ≤2500 gm, with a sensitivity of 93% and specificity of 49% MAC of ≤9 cm, predicts a birth weight of ≤2000 gm, with a sensitivity of 95% and specificity of 87%. Regression values were analyzed and formula for detecting birth weight for the given MAC was derived.Conclusions: A positive correlation existed between midarm circumference and birth weight (p<0.001). A cut off value of 10 cm of MAC for identification of low-birth-weight babies weighting ≤2500 gm and 9 cm of MAC for identification of low-birth-weight babies ≤2000 gm with optimum sensitivity and specificity.

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Hong, Sungjin, Heechai Kang, Jusung Kim, and Kunhee Cho. "Low Voltage Time-Based Matrix Multiplier-and-Accumulator for Neural Computing System." Electronics 9, no. 12 (2020): 2138. http://dx.doi.org/10.3390/electronics9122138.

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A time-based matrix multiply-and-accumulate (MAC) operation for a neural computing system is described. A simple and compact time-based matrix MAC structure is proposed that can perform multiplication and accumulation simultaneously in a single multiplier structure, and the hardware complexity is not affected by the matrix input size. To enhance the linearity of the weight factor, an offset-free pulse-width modulator is introduced. The proposed MAC architecture operates at a low supply voltage of 0.5 V while it consumes MAC energy of 0.38 pJ with a 32 nm low-power (LP) predictive technology model (PTM) CMOS process. In addition, the near-subthreshold operation can remove the level shifter to interface between the MAC operator and digital circuits such as static random-access-memory (SRAM) because both can utilize the same level of the supply voltage. The proposed MAC is based on a digital intensive pulse-width modulation, and thus it can further improve its performance and area with more advanced technologies.

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Abreu, Mariana, Delia Aguado, Javier Benito, and Ignacio A. Gómez de Segura. "Reduction of the sevoflurane minimum alveolar concentration induced by methadone, tramadol, butorphanol and morphine in rats." Laboratory Animals 46, no. 3 (2012): 200–206. http://dx.doi.org/10.1258/la.2012.010066.

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This study aimed to estimate the reduction in the minimum alveolar concentration (MAC) of sevoflurane induced by low and high doses of methadone (5 and 10 mg/kg), tramadol (25 and 50 mg/kg), butorphanol (5 and 10 mg/kg) or morphine (5 and 10 mg/kg) in the rat. A control group received normal saline. Sixty-three adult male Sprague-Dawley rats were anaesthetized with sevoflurane ( n = 7 per group). Sevoflurane MAC was then determined before and after intraperitoneal administration of the opioids or saline. The duration of the sevoflurane MAC reduction and basic cardiovascular and respiratory measurements were also recorded. The baseline MAC was 2.5 (0.3) vol%. Methadone, tramadol and morphine reduced the sevoflurane MAC (low dose: 31 ± 10, 38 ± 15 and 30 ± 13% respectively; high dose: 100 ± 0, 83 ± 17 and 77 ± 25%, respectively) in a dose-dependent manner. The low and high doses of butorphanol reduced the sevoflurane MAC to a similar extent (33 ± 7 and 31 ± 4%, low and high doses, respectively). Two rats developed apnoea following administration of high-dose butorphanol and methadone. These anaesthetic-sparing effects are clinically relevant and may reduce the adverse effects associated with higher doses of inhalational anaesthetics.

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Tsai, Alan C., and Tsui-Lan Chang. "The effectiveness of BMI, calf circumference and mid-arm circumference in predicting subsequent mortality risk in elderly Taiwanese." British Journal of Nutrition 105, no. 2 (2010): 275–81. http://dx.doi.org/10.1017/s0007114510003429.

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BMI, mid-arm circumference (MAC) and calf circumference (CC) are anthropometric indicators often included in geriatric health measurement scales. However, their relative effectiveness in predicting long-term mortality risk has not been extensively examined. The present study aimed to evaluate the relative effectiveness of these anthropometrics in predicting long-term mortality risk in older adults. The study prospectively analysed the ability of these indicators in predicting 4-year follow-up mortality risk of a population-representative sample of 4191 men and women, 53 years of age or older in the ‘Survey of Health and Living Status of the Elderly in Taiwan’. Cox regression analyses were performed to evaluate the association of follow-up mortality risk with low ( < 21 kg/m2) or high ( ≥ 27 kg/m2) BMI, low MAC ( < 23·5/22 cm for men/women) and low CC ( < 30/27 cm) respectively, according to Taiwanese-specific cut-off points. Results showed that low CC and low MAC were more effective than low BMI in predicting follow-up mortality risk in 65–74-year-old elderly. But low CC and low BMI were more effective than low MAC in ≥ 75-year-old elderly, and low BMI was more effective than low MAC or low CC in 53–64-year-old persons. High BMI was not effective in predicting mortality risk in any of these age ranges. These results suggest that in elderly adults, CC is more effective than BMI in predicting long-term mortality risk. Thus, more consideration to CC and MAC in designing geriatric health or nutritional measurement scales is recommended.

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Liang, Lulu, Xiaonan Liu, Yongtao Wang, Weiduan Feng, and Guang Yang. "SW-MAC: A Low-Latency MAC Protocol with Adaptive Sleeping for Wireless Sensor Networks." Wireless Personal Communications 77, no. 2 (2013): 1191–211. http://dx.doi.org/10.1007/s11277-013-1561-6.

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Hwang, Kwang-il, and Gangman Yi. "Adaptive Low-Power Listening MAC Protocol Based on Transmission Rates." Scientific World Journal 2014 (2014): 1–6. http://dx.doi.org/10.1155/2014/473132.

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Even though existing low-power listening (LPL) protocols have enabled ultra-low-power operation in wireless sensor networks (WSN), they do not address trade-off between energy and delay, since they focused only on energy aspect. However, in recent years, a growing interest in various WSN applications is requiring new design factors, such as minimum delay and higher reliability, as well as energy efficiency. Therefore, in this paper we propose a novel sensor multiple access control (MAC) protocol, transmission rate based adaptive low-power listening MAC protocol (TRA-MAC), which is a kind of preamble-based LPL but is capable of controlling preamble sensing cycle adaptively to transmission rates. Through experiments, it is demonstrated that TRA-MAC enables LPL cycle (LC) and preamble transmission length to adapt dynamically to varying transmission rates, compensating trade-off between energy and response time.

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Li, Suoping, Youyi Yuan, and Guodong Pan. "An Efficient SS-MAC Protocol for IEEE 802.15.4-Based WSNs of Cluster Tree Topology." Electronics 13, no. 13 (2024): 2520. http://dx.doi.org/10.3390/electronics13132520.

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Wireless sensor networks (WSNs) based on the IEEE 802.15.4 standard have important applications in many fields, such as the Internet of Things and smart cities because of their low energy consumption. Hybrid carrier sense multiple access/time division multiple access (CSMA/TDMA) is the key technique to reduce energy consumption in the standard, but it also increases packet delay and reduces network throughput. Although the cluster tree topology is a typical topology defined by the IEEE 802.15.4 standard, there are few efficient medium access control (MAC) protocols specifically for this type of topology. To this end, we present an improved hybrid CSMA/TDMA MAC protocol based on a sharable slot algorithm for WSNs with cluster tree topology, called sharable slot-based MAC (SS-MAC). By designing the operating mechanism and frame structure, improving the hybrid CSMA/TDMA and channel-hopping techniques of IEEE 802.15.4 MAC, and introducing a sharable slot algorithm to wake up tree nodes asynchronously as well as a short address strategy to identify member nodes, the proposed protocol improves packet delay and throughput under the premise of low collision and low node energy consumption. Moreover, we derive mathematical expressions of the parameters of the sharable slot algorithm and evaluate the energy consumption, throughput and packet delay of the SS-MAC based on the queue modeling of packet arrivals. Numerical simulations verify that the proposed MAC protocol outperforms the other three existing MAC protocols, namely, IEEE 802.15.4 MAC, SSMA and LELLMAC, in terms of energy consumption, throughput and packet delay.

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Ahmed, Aliyu, Paul D. Mitchell, Yuriy Zakharov, and Nils Morozs. "FD-LTDA-MAC: Full-Duplex Unsynchronised Scheduling in Linear Underwater Acoustic Chain Networks." Applied Sciences 11, no. 22 (2021): 10967. http://dx.doi.org/10.3390/app112210967.

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In-band full-duplex communication offers significant potential to enhance network performance. This paper presents the full-duplex linear transmit delay allocation MAC (FD-LTDA-MAC) protocol for full-duplex based underwater acoustic chain networks (FD-UACNs) for subsea pipeline monitoring. This incorporates a number of extensions to the LTDA-MAC protocol in order to fully exploit advantages of full-duplex communication to enhance the efficiency of underwater facility monitoring. The protocol uses a greedy optimisation algorithm to derive collision-free packet schedules for delivering data packets to the sink node of the underwater chain network. The purpose of this paper is to show the significant improvement that can be achieved in packet scheduling by exploiting temporal spectrum re-use of an underwater acoustic channel through full-duplex communication. Simulation results show that more efficient packet scheduling and reduced end-to-end packet delays can be achieved in large scale scenarios using FD-LTDA-MAC compared with LTDA-MAC and LTDA-MAC with full-duplex enabled nodes. It can provide much higher monitoring rates for long range underwater pipelines using low cost, mid range, low rate, and low power acoustic modems.

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Falkinham, Joseph O. "Mycobacterium avium Complex (MAC) in Water Distribution Systems and Household Plumbing in the United States." Water 12, no. 12 (2020): 3338. http://dx.doi.org/10.3390/w12123338.

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Members of the Mycobacterium avium complex (MAC) are waterborne, opportunistic pathogens whose characteristics make urban water distribution systems and household plumbing ideal habitats for their survival, persistence and growth. Rather than contaminants, MAC are colonists of drinking water systems. MAC are normal inhabitants of natural soils and water, and enter drinking water treatment systems through surface sources. A proportion of MAC survive transmission through the treatment plant, and regrow in the distribution system and household plumbing. Once within household plumbing, MAC adhere to surfaces and form biofilms, thus preventing their washout. The thermal tolerance of MAC leads to growth in water heating systems. Stagnation does not reduce MAC numbers, as MAC can grow at low oxygen levels. MAC present challenges to current water monitoring approaches as their numbers do not correlate with E. coli, fecal coliforms or heterotrophic plate count bacteria.

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Iwasaki, Takuya, Fumihiro Yamaguchi, Makoto Hayashi, et al. "Combination of anti-glycopeptidolipid-core IgA antibody and clinical features for diagnosing potential nontuberculous mycobacterium pulmonary disease in routine practice." Therapeutic Advances in Respiratory Disease 16 (January 2022): 175346662211380. http://dx.doi.org/10.1177/17534666221138002.

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Background: The anti- Mycobacterium avium complex (MAC) antibody test measures levels of IgA antibody against the glycopeptidolipid (GPL) core in the bacterial cell walls and is a useful clinical indicator of nontuberculous mycobacterium pulmonary disease (NTM-PD). However, it is not currently possible to diagnose the disease using anti-MAC antibodies alone. Objectives: The study aim was to assess the efficacy of the combination of anti-MAC antibodies and clinical findings for diagnosing potential NTM-PD. Methods: This cross-sectional study included 938 patients tested using the anti-MAC antibody. NTM-PD was diagnosed by multiple positive cultures of the same species in sputum samples. Multivariate logistic regression models were used to identify the clinical factors related to NTM-PD. Results: Overall, 19.6% (184/938) of participants were diagnosed with NTM-PD. In multivariate analysis, positive anti-MAC antibodies, low body mass index, absence of malignancy, and cavity-forming lung lesions were significantly associated with NTM-PD at diagnosis. The positive rates of the anti-MAC antibody test were 79.4% (135/170) for MAC and 55.6% (5/9) for Mycobacterium abscessus complex, respectively. Conclusions: Bronchoscopic examinations should be performed especially in certain types of individuals from whom sputum samples cannot be obtained. Anti-MAC antibodies are also positive in patients other than those harboring MAC, but the rate may be low because of the different components in GPLs.

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Petrosky, Eric E., Alan J. Michaels, and Joseph M. Ernst. "A Low Power IoT Medium Access Control for Receiver-Assigned CDMA." International Journal of Interdisciplinary Telecommunications and Networking 11, no. 2 (2019): 24–41. http://dx.doi.org/10.4018/ijitn.2019040103.

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Low power, low cost, and security-conscious wireless sensor networks are becoming increasingly pervasive in the internet of things (IoT). In these networks, receiver-assigned code division multiple access (RA-CDMA) offers benefits over existing multiple access techniques. RA-CDMA networks are asynchronous, robust against multipath interference, and offer resilience against collision. A lightweight medium access control (MAC) protocol is needed to facilitate communication in RA-CDMA networks between low power sensor nodes and access points. This article provides an overview of RA-CDMA and proposes elements of a new MAC protocol that could improve performance of certain wireless sensor networks. Key features of the proposed MAC design are introduced and compared to those of existing protocols, highlighting its simple and lightweight design. Through its compatibility with RA-CDMA, the MAC design eliminates significant overhead and complexity while meeting requirements for low power networks, which enables the implementation of dense IoT sensor networks.

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Bejanyan, Nelli, Mei-Jie Zhang, Khalid Bo-Subait, et al. "Myeloablative Conditioning Is Preferred for Allogeneic Transplantation of Acute Myeloid Leukemia and Myelodysplastic Syndromes with Low/Intermediate but Not High Disease Risk Index." Blood 134, Supplement_1 (2019): 4603. http://dx.doi.org/10.1182/blood-2019-123513.

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Although some data (Scott, JCO 2017) suggest that myeloablative conditioning (MAC) is preferred for allogeneic hematopoietic cell transplantation (HCT) in acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS), these data were not informed by analysis of disease specific risk factors. We analyzed AML and MDS HCT outcomes stratified by the disease risk index (DRI) in order to identify the preferred transplant conditioning intensity (reduced-intensity conditioning [RIC] vs. MAC). In this large CIBMTR registry study we identified 4387 adult patients (age 40-65 years) who received HCT for AML (68%) or MDS (32%) between 2009 and 2015. DRI was stratified as low/ intermediate risk (1539 MAC and 999 RIC) and high/ very high risk (1121 MAC and 728 RIC). Examining the low/ intermediate risk DRI cohort (Table), RIC was associated with lower risk of TRM (HR=0.74, 95% CI 0.62-0.88; p<0.001) but significantly higher risk of relapse (HR=1.54, 95% CI 1.35-1.76; p<0.001). As a result, RFS in this cohort was significantly worse with RIC (HR=1.19, 95% CI 1.07-1.33; p=0.001). In the high/ very high risk DRI cohort, RIC resulted in similar TRM (HR=0.83, 95% CI 0.68-1.00; p=0.051) but again significantly higher risk of relapse (HR=1.23, 95% CI 1.08-1.41; p=0.002). RFS in high/ very high risk DRI cohort was similar between RIC and MAC. Adjusted outcome curves for the 3 endpoints are shown in the Figure. In this large study of HCT for AML or MDS stratified by DRI, RIC was independent predictor of lower TRM, but significantly higher risk of relapse. The MAC was an independent predictor of lower relapse in both low/ intermediate and high/very high DRI groups. However, MAC only resulted in RFS benefit in the low/ intermediate group where the magnitude of impact on relapse was not offset by the higher TRM. In adults with AML or MDS aged 40-65 years, these data support MAC as the preferred conditioning intensity for low/ intermediate risk DRI, whereas MAC does not provide significant benefit in those with high/ very high risk DRI. Safer, yet still potent MAC regimens could benefit this higher risk group. Disclosures Bejanyan: Kiadis Pharma: Other: advisory board. Brunstein:Gamida: Research Funding; Astex: Research Funding; Magenta: Research Funding. Kebriaei:Amgen: Research Funding; Jazz: Consultancy; Pfizer: Honoraria; Kite: Honoraria; Pfizer: Honoraria; Kite: Honoraria. Weisdorf:Fate Therapeutics: Consultancy; Pharmacyclics: Consultancy; Incyte: Research Funding.

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Rungrodnimitchai, Supitcha, and Suphatra Hiranphinyophat. "The Functionalization of Activated Carbon by Oxidation." Key Engineering Materials 846 (June 2020): 251–56. http://dx.doi.org/10.4028/www.scientific.net/kem.846.251.

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Activated carbon is one of the most widely used adsorbents, but it shows low removal efficiency for polar molecules such as ammonia or ions due to the low content of oxygen containing groups. To increase the amount of oxygen containg groups, activated carbon was modified by the oxidation of activated carbon using the HNO3/H3PO4-NaNO2. The results showed that the carboxyl content of the modified activated carbon (MAC) increased with an increase in reaction time and temperature. The condition at 50°C for 60 hours yielded the MAC with a carboxyl content 1.07 mmol/g. The oxygen content of MAC also increased, suggesting the formation of carboxyl or carbonyl groups in the products after the oxidation. Brunauer-Emmett-Teller (BET) analysis and scanning electron microscopy (SEM) images demonstrated an increase in porosity of the MAC. The maximum capacity of ammonia adsorption was 5.81 mg/g for MAC.

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Therese Aby, Affoua, Alexandre Guitton, Pascal Lafourcade, and Michel Misson. "History-based MAC Protocol for Low Duty-Cycle Wireless Sensor Networks: the SLACK-MAC Protocol." ICST Transactions on Mobile Communications and Applications 3, no. 8 (2017): 153340. http://dx.doi.org/10.4108/eai.13-9-2017.153340.

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Zacharias, Sven, and Thomas Newe. "Competition at the Wireless Sensor Network MAC Layer: Low Power Probing interfering with X-MAC." Journal of Physics: Conference Series 307 (August 17, 2011): 012038. http://dx.doi.org/10.1088/1742-6596/307/1/012038.

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Thérèse Aby, Affoua, Alexandre Guitton, Pascal Lafourcade, and Michel Misson. "History-based MAC Protocol for Low Duty-Cycle Wireless Sensor Networks: the SLACK-MAC Protocol." ICST Transactions on Mobile Communications and Applications 2, no. 7 (2016): 151516. http://dx.doi.org/10.4108/eai.20-6-2016.151516.

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Beck, Christoph, Jörg Nagel, Peter Hevesi, and Georg Bretthauer. "RTS-MAC: A Relative Time Synchronization MAC Protocol for Low Duty Cycle Body Sensor Networks." International Journal of Wireless Information Networks 19, no. 3 (2012): 163–72. http://dx.doi.org/10.1007/s10776-012-0185-1.

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Tang, Hong-Wei, Jian-Nong Cao, Xue-Feng Liu, and Cai-Xia Sun. "SR-MAC: A Low Latency MAC Protocol for Multi-Packet Transmissions in Wireless Sensor Networks." Journal of Computer Science and Technology 28, no. 2 (2013): 329–42. http://dx.doi.org/10.1007/s11390-013-1334-4.

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Park, Hye-bin, Jinoo Joung, and Byeongseog Choe. "TDMA-based MAC Protocol for Implementation of Ultra-low latency in Vehicular networks." Journal of the Institute of Internet Broadcasting and Communication 17, no. 1 (2017): 33–39. http://dx.doi.org/10.7236/jiibc.2017.17.1.33.

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Gómez de Segura, Ignacio A., Javier Benito de la Vibora, and Delia Aguado. "Opioid Tolerance Blunts the Reduction in the Sevoflurane Minimum Alveolar Concentration Produced by Remifentanil in the Rat." Anesthesiology 110, no. 5 (2009): 1133–38. http://dx.doi.org/10.1097/aln.0b013e31819dadaf.

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Background Acute opioid tolerance is a known entity leading to reduced analgesic efficacy of these drugs in the postoperative period. However, the development of acute opioid tolerance in the very short term, i.e., during the intraoperative period when opioids are being administered, has not been reported. Therefore, the aim of this study was to determine if acute opioid tolerance could develop and limit the opioid-induced reduction in the minimum alveolar concentration (MAC) for inhalant anesthetics. Methods Male Wistar rats were randomly allocated to receive two doses of remifentanil (120 and 240 microg . kg(-1) . h(-1)) under sevoflurane anesthesia, and the sevoflurane MAC was determined before and at two time intervals afterwards. In a second experiment, the low dose of remifentanil was increased once an acute opioid tolerance effect was observed. The sevoflurane MAC was determined from alveolar gas samples at the time of tail clamp. Results A remifentanil constant rate of infusion dose-dependently reduced the sevoflurane MAC from 2.4 to 1.8 +/- 0.2 vol% and from 2.3 +/- 0.3 vol% to 1.5 +/- 0.3 vol%, at the low and high doses, respectively. However, 90 min later, when the sevoflurane MAC was redetermined, the observed reduction was blunted to nearly 50% of the previous sevoflurane MAC values. When this acute opioid tolerance effect was observed with the low dose, the sevoflurane MAC reduction originally achieved could be reattained by doubling the dose; i.e., giving the high dose. Conclusions Remifentanil efficacy in reducing the sevoflurane MAC diminishes within a short term, suggesting that increased opioid doses may be required to maintain intraoperative analgesia during sevoflurane anesthesia.

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Wakamatsu, Kentaro, Nobuhiko Nagata, Sanae Maki, et al. "Patients with MAC Lung Disease Have a Low Visceral Fat Area and Low Nutrient Intake." Pulmonary Medicine 2015 (2015): 1–5. http://dx.doi.org/10.1155/2015/218253.

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Objective.This study aimed to examine the nutritional status and nutrient intake of patients with MAC lung disease with a focus on visceral fat area.Patients and Methods.Among 116 patients of our hospital with nontuberculous mycobacteriosis who were registered between May 2010 and August 2011, 103 patients with MAC lung disease were included in this study. In all patients, nutritional status and nutrient intake were prospectively examined.Results.Patients were 23 men and 80 women (mean age,72.3±10.9years). BMI (kg/m2) at the time of registration was20.4±2.7in men and19.2±2.9in women. Visceral fat area (cm2) was significantly lower in women (35.7±26.6) than in men (57.5±47.4) (p=0.0111). The comparison with general healthy adults according to age revealed a markedly reduced visceral fat area among patients with MAC lung disease. With respect to nutrient intake, energy adequacy (86.1±15.7%), protein adequacy (82.4±18.2%), lipid adequacy (78.1±21.8%), and carbohydrate adequacy (89.6±19.2%) ratios were all low at the time of registration. BMI was significantly correlated with protein adequacy (p=0.0397) and lipid adequacy (p=0.0214) ratios, while no association was found between visceral fat area and nutrient intake.Conclusion.Patients with MAC lung disease had a low visceral fat area and low nutrient intake.

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LEE, Young-Geun, Han-Sam JUNG, and Ki-Seok CHUNG. "Low Power MAC Design with Variable Precision Support." IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences E92-A, no. 7 (2009): 1623–32. http://dx.doi.org/10.1587/transfun.e92.a.1623.

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Aji, Hélène. "S'écrire l'histoire : Mac Low, Silliman, Hejinian, Watten, Goldsmith." Études anglaises 61, no. 2 (2008): 177. http://dx.doi.org/10.3917/etan.612.0177.

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Pillai, R. V. K., D. Al-Khalili, and A. J. Al-Khalili. "Low power architecture for floating point MAC fusion." IEE Proceedings - Computers and Digital Techniques 147, no. 4 (2000): 288. http://dx.doi.org/10.1049/ip-cdt:20000481.

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Langendoen, Koen, and Andreas Meier. "Analyzing MAC protocols for low data-rate applications." ACM Transactions on Sensor Networks 7, no. 2 (2010): 1–40. http://dx.doi.org/10.1145/1824766.1824775.

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Liu, Xin, Xiujuan Du, Meiju Li, Lijuan Wang, and Chong Li. "A MAC Protocol of Concurrent Scheduling Based on Spatial-Temporal Uncertainty for Underwater Sensor Networks." Journal of Sensors 2021 (March 27, 2021): 1–15. http://dx.doi.org/10.1155/2021/5558078.

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Underwater sensor networks (UWSNs) are characterized by large energy consumption, limited power supply, low bit rate, and long propagation delay, as well as spatial-temporal uncertainty, which present both challenges and opportunities for media access control (MAC) protocol design. The time-division transmissions can effectively avoid collisions since different nodes transmit packets at different period of time. Nevertheless, in UWSNs with long propagation delay, in order to avoid collisions, the period of time is subject to be long enough, which results in poor channel utilization and low throughput. In view of the long and different propagation delay between a receiving node and multiple sending nodes in UWSNs, as long as there is no collision at the receiving node, multiple sending nodes can transmit packets simultaneously. Therefore, in this paper, we propose a MAC protocol of concurrent scheduling based on spatial-temporal uncertainty called CSSTU-MAC (concurrent scheduling based on spatial-temporal uncertainty MAC) for UWSNs. The CSSTU-MAC protocol utilizes the characteristics of temporal-spatial uncertainty as well as long propagation delay in UWSNs to achieve concurrent transmission and collision avoidance. Simulation results show that the CSSTU-MAC protocol outperforms the existing MAC protocol with time-division transmissions in terms of average energy consumption and network throughput.

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Nguyen, Kien, Yusheng Ji, and Shigeki Yamada. "Low Overhead MAC Protocol for Low Data Rate Wireless Sensor Networks." International Journal of Distributed Sensor Networks 9, no. 4 (2013): 217159. http://dx.doi.org/10.1155/2013/217159.

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Zhuang, Yong Long, Xiao Lan Weng, and Xiang He Wei. "Virtual Clustered MAC Layer Protocol Design of a Wireless Sensor Network: ES-MAC." Applied Mechanics and Materials 687-691 (November 2014): 1749–53. http://dx.doi.org/10.4028/www.scientific.net/amm.687-691.1749.

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Sensor-MAC (S-MAC), one kind of use common type activities / sleep cycle wireless sensor network MAC layer protocol, we propose a strengthening type Enhanced S-MAC, called ES-MAC, and part of its application in wireless sensor networks than the outer layer of low traffic. ES-MAC is divided into three stages: the first stage is to create a virtual cluster region and preset transmission path; third stage of data transfer; second stage of data collection and sorting. Sensing node virtual cluster in the region, competitive manner using micro slot (Mini-Slot) determine the order of data transmission. In the data transfer phase has been established using the sequential transfer of data, the sense node in order to reduce the unnecessary and excessive collision monitoring, sleep time, and the growth of nodes. Simulation results show that, ES-MAC under different flow and different cycles, compared with S-MAC has lower average packet delay time.

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Hoda, Md Durul. "Mitral Annular Calcification Detected by Transthoracic Echocardiography is a Marker for High Prevalence and Severity of Angiographically Proven Coronary Artery Disease." Annals of International Medical and Dental Research 8, no. 2 (2022): 180–91. http://dx.doi.org/10.53339/aimdr.2022.8.2.24.

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Background: MAC was defined as a dense, localized, highly reflective area at the base of the posterior mitral leaflet detected by TTE. Obstructive CAD was defined as either 50% reduction of the internal diameter of the left main coronary artery or 70% reduction of the internal diameter of the left anterior descending, right coronary, or left circumflex artery distribution. Objective: The aim of the study was to evaluate the role of echocardiographically detected MAC as a predictor of coronary artery disease (CAD).Material & Methods:In this prospective, observational, case-control study, coronary angiography was done in 50 patients with MAC and equal number of patients without MAC, detected with transthoracic echocardiography. Analysis was done to observe the association and correlation of MAC with angiographic findings.Results:Mean age of the case control was 55.16 ± 10.73 years and control was 49.80 ± 8.84 years. In this study 34% of patients with MAC and 32% patients without MAC had single vessel disease, 16% of patients with MAC and 24% patients without MAC had double vessel disease, 42% of patients with MAC and 22% patients without MAC had triple vessel disease (TVD), 16% of patients with MAC and 4% patients without MAC had Left main coronary artery disease and 8% of patients with MAC and 22% patients without MAC had no significant CAD.Multivariate analysis shows MAC (p=0.049) as an independent predictor for coronary artery disease (CAD).Conclusions:Transthoracic echocardiographically detected MAC is an independent predictor of coronary artery disease. The low cost, portable and radiation free nature of the ultrasound approach make MAC an attractive parameter in the ongoing search for the ideal marker of coronary artery disease (CAD).

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Sadamatsu, Hironori, Koichiro Takahashi, Hiroki Tashiro, et al. "A Low Body Mass Index Is Associated with Unsuccessful Treatment in Patients with Mycobacterium avium Complex Pulmonary Disease." Journal of Clinical Medicine 10, no. 8 (2021): 1576. http://dx.doi.org/10.3390/jcm10081576.

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Background: A low body mass index (BMI) has been reported to be a poor prognostic factor for Mycobacterium avium complex pulmonary disease (MAC-PD). The purpose of this study was to clarify the clinical features of MAC-PD in cases with a low BMI. Methods: This retrospective study analyzed the data of patients diagnosed with MAC-PD at Saga University Hospital between 2008 and 2019. The analyzed patient characteristics included age, gender, BMI, symptoms, laboratory data, chest computed tomography findings, and the treatment courses. We also investigated the factors associated with successful treatment. Results: In total, 144 patients were included in this study. The low-BMI group (BMI < 18.5 kg/m2) had a higher incidence of sputum, Mycobacterium intracellurare infection, and cavitary lesions, in addition to lower blood lymphocyte counts, higher neutrophil–lymphocyte ratios, and a lower prognostic nutritional index (PNI) when compared to the preserved-BMI group (BMI ≥ 18.5 kg/m2). Sixty-six of the 144 patients (45.8%) received treatment. Hemosputum, acid-fast bacillus sputum smear positivity, low lymphocyte counts, a low PNI, and unsuccessful treatment (48.5% vs. 24.2%, p < 0.05) were found to be associated with a low BMI. Conclusions: A low BMI is associated with cavitary lesions, malnutrition, and unsuccessful treatment in MAC-PD.

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Negatu, Yihenew, and Eyasu Mekonen. "A Case Report of Mycobacterium Avium Complex Peritonitis in an AIDS Patient." Case Reports in Infectious Diseases 2013 (2013): 1–2. http://dx.doi.org/10.1155/2013/590478.

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Peritonitis due to Mycobacterium avium complex (MAC) infection is uncommon. The risk for MAC in AIDS patients is greatest in those with severely depressed CD4 count. The organs most commonly involved in disseminated MAC infection include spleen, mesenteric lymph nodes, liver, and intestines. The involvement of peritoneum by MAC infection is rare. This is a case of MAC peritonitis in a 26-year-old female AIDS patient who is noncompliant to highly active antiretroviral therapy (HAART). This patient presented with abdominal pain and distension, anorexia, diarrhea, and cough. She was treated with rifabutin, clarithromycin, and ethambutol along with atovaquone for Pneumocystis jiroveci pneumonia prophylaxis and so the patient’s condition improved. MAC peritonitis should be considered in a patient presenting with nonspecific abdominal symptoms in the setting of AIDS and low CD4 count.

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Peixoto, Pablo M., Shin-Young Ryu, Agnes Bombrun, Bruno Antonsson, and Kathleen W. Kinnally. "MAC inhibitors suppress mitochondrial apoptosis." Biochemical Journal 423, no. 3 (2009): 381–87. http://dx.doi.org/10.1042/bj20090664.

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MAC (mitochondrial apoptosis-induced channel) forms in the mitochondrial outer membrane and unleashes cytochrome c to orchestrate the execution of the cell. MAC opening is the commitment step of intrinsic apoptosis. Hence closure of MAC may prevent apoptosis. Compounds that blocked the release of fluorescein from liposomes by recombinant Bax were tested for their ability to directly close MAC and suppress apoptosis in FL5.12 cells. Low doses of these compounds (IC50 values ranged from 19 to 966 nM) irreversibly closed MAC. These compounds also blocked cytochrome c release and halted the onset of apoptotic markers normally induced by IL-3 (interleukin-3) deprivation or staurosporine. Our results reveal the tight link among MAC activity, cytochrome c release and apoptotic death, and indicate this mitochondrial channel is a promising therapeutic target.

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Skolnik, Jennifer, Robert Weiss, Andrew J. Meyr, et al. "Evaluating the Impact of Medial Arterial Calcification on Outcomes of Infrageniculate Endovascular Interventions for Treatment of Diabetic Foot Ulcers." Vascular and Endovascular Surgery 55, no. 4 (2021): 382–88. http://dx.doi.org/10.1177/1538574421993314.

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Background: Medial arterial calcification (MAC) of the tibial and pedal arteries has been associated with an increased risk of amputation among people with diabetes. Endovascular interventions on infrageniculate vessels are frequently performed with the intent of treating peripheral artery disease (PAD) and decreasing the risk of amputation in those with diabetes. This study aimed to investigate how the extent of MAC impacts outcomes of endovascular procedures in people with diabetic foot ulcers (DFU). Methods: We identified all patients who had undergone infrageniculate angioplasty in the setting of DFU at our institution between 2009 and 2019. Subjects were assigned a MAC score based on the severity of MAC in each vessel visualized on plain radiographs of the ankle and foot. We evaluated the relationship between MAC and the primary outcome, major adverse limb event (MALE), using stratified Cox proportional modeling. Results: Among 99 subjects with DFU who had undergone infrageniculate angioplasty, MALE occurred in 50% (95% confidence interval [CI] 38%-61%) of patients within 1 year of intervention. On univariate Cox regression analysis, each 1 point increment in MAC score (hazard ratio [HR], 1.09; 95% CI 1.01-1.18), the third tertile of MAC score (HR, 2.27; 95% CI 1.01-5.11), age (HR 0.96; 95% CI 0.93-0.99), and wound grade (HR, 5.34; 95% CI 2.17-13.14), were significantly associated with increased risk of MALE. On adjusted analysis stratified by wound grade, MAC score was found to be associated with MALE only in patients with a low wound grade. Conclusion: Increased severity of MAC is associated with increased risk of MALE for subjects undergoing infrageniculate angioplasty with a low wound grade. Further research is needed to better understand the complex relationships of MAC, PAD, DFU, and interventions aimed at promoting healing of DFU.

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Allen, John P., Vivian Faden, Robert Rawlings, and Ann Miller. "Subtypes of Substance Abusers: Personality Differences Associated with MacAndrew Scores." Psychological Reports 66, no. 2 (1990): 691–98. http://dx.doi.org/10.2466/pr0.1990.66.2.691.

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Several earlier studies have reported clinically relevant personality correlates of high vs low scores on the MacAndrew Scale ( Mac) of the MMPI. Unfortunately, these projects have not adjusted for age or nature of abuse. Also, most have assumed that the personality correlates are the same for female patients as for male patients. This study attempts to address these deficiencies. Even after correcting for age and diagnosis, high Mac patients differ from low Mac patients on major scales of the MMPI. The pattern of such differences varies considerably between men and women. Substance abuse treatment implications of these differences are discussed.

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Haszerila Wan Hassan, Wan, Darmawaty Mohd Ali, Juwita Mohd Sultan, and Murizah Kassim. "Medium access control protocol based on time division multiple access scheme for wireless body area network." International Journal of Electrical and Computer Engineering (IJECE) 14, no. 3 (2024): 2762. http://dx.doi.org/10.11591/ijece.v14i3.pp2762-2770.

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In recent years, the demand for wireless body area network (WBAN) technology has increased, driven by advancements in medical and healthcare applications. WBAN consists of small, low-power, and heterogeneous sensor devices attached inside or outside the body for continuous health monitoring. Medium access control (MAC) is pivotal in addressing WBAN challenges by ensuring reliability and energy efficiency under a dynamic environment caused by body movement. Therefore, to tackle these challenges, this paper presents a MAC protocol based on time division multiple access (TDMA) to enhance the WBAN performance. The proposed TDMA-MAC protocol employs a one-periodic scheduled-based access method to provide reliable data transmission while satisfying the WBAN requirements. The proposed protocol is compared to the IEEE 802.15.6 MAC, enhanced packet scheduling algorithm MAC (EPSA-MAC), and concurrent MAC (C-MAC) protocols based on the performance metrics of packet delivery ratio (PDR), network throughput, energy consumption, and average delay. The simulation results show that the TDMA-MAC protocol outperforms its competitors as it could achieve up to 98% PDR, 30% enhanced throughput, 30% energy optimization, and 20% improvement in average delay.

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Wan, Haszerila Wan Hassan, Mohd Ali Darmawaty, Mohd Sultan Juwita, and Kassim Murizah. "Medium access control protocol based on time division multiple access scheme for wireless body area network." International Journal of Electrical and Computer Engineering (IJECE) 14, no. 3 (2024): 2762–70. https://doi.org/10.11591/ijece.v14i3.pp2762-2770.

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In recent years, the demand for wireless body area network (WBAN) technology has increased, driven by advancements in medical and healthcare applications. WBAN consists of small, low-power, and heterogeneous sensor devices attached inside or outside the body for continuous health monitoring. Medium access control (MAC) is pivotal in addressing WBAN challenges by ensuring reliability and energy efficiency under a dynamic environment caused by body movement. Therefore, to tackle these challenges, this paper presents a MAC protocol based on time division multiple access (TDMA) to enhance the WBAN performance. The proposed TDMA-MAC protocol employs a one-periodic scheduled-based access method to provide reliable data transmission while satisfying the WBAN requirements. The proposed protocol is compared to the IEEE 802.15.6 MAC, enhanced packet scheduling algorithm MAC (EPSA-MAC), and concurrent MAC (C-MAC) protocols based on the performance metrics of packet delivery ratio (PDR), network throughput, energy consumption, and average delay. The simulation results show that the TDMA-MAC protocol outperforms its competitors as it could achieve up to 98% PDR, 30% enhanced throughput, 30% energy optimization, and 20% improvement in average delay.

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Graves, V., T. Gabig, L. McCarthy, EF Strour, T. Leemhuis, and D. English. "Simultaneous mobilization of Mac-1 (CD11b/CD18) and formyl peptide chemoattractant receptors in human neutrophils [published erratum appears in Blood 1993 Mar 15;81(6):1668]." Blood 80, no. 3 (1992): 776–87. http://dx.doi.org/10.1182/blood.v80.3.776.776.

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Abstract Mobilization of a distinct subset of specific granules provides a physiologically important mechanism to recruit Mac-1 (CD11b/CD18) from an intracellular pool to the external surface of the neutrophil plasma membrane, where the functionally active heterodimer mediates several adherence-dependent processes that are crucial for adequate host defense and cellular inflammatory responses. We observed similar characteristics for translocation of Mac-1 and neutrophil formyl peptide receptors (FPR) and hypothesize that the readily accessible pools of both Mac-1 and FPR are colocalized within this specific granule subset. Plasma membrane levels of both FPR (assessed with 3H- FMLP) and Mac-1 (assessed by fluorescence-activated cell sorter analysis of fluorescein isothiocyanate [FITC]-Mo-1-labeled cells) were markedly downregulated in cells prepared at low temperature from blood cooled to 4 degrees C immediately after removal from the circulation. Levels of both FPR and Mac-1 remained low on cells held at 4 degrees C. Upon warming, spontaneous upregulation of Mac-1 and FPR occurred with similar kinetics and temperature dependency. Translocation of both Mac- 1 and FPR was markedly potentiated by exposure of cells to either fluoride ion (which has been shown by others to specifically elicit exocytosis of gelatinase-rich and vitamin B-12 binding protein-poor granules) or granulocyte-macrophage colony-stimulating factor (GM-CSF), a cytokine that markedly potentiates the neutrophils' host defense capabilities. Levels of both FPR and Mac-1 on F-- or GM-CSF-treated neutrophils exceeded those present on cells incubated at 37 degrees C for extended time intervals, indicating that stimulated translocation may involve mobilization of an additional granule subset. Scatchard analysis showed that only low-affinity FPR were translocated during spontaneous and stimulus-dependent upregulation. To directly compare FPR levels on the surface of cells displaying varying levels of Mac-1 within a single cell suspension, cells were labeled with FITC-Mo-1 and sorted into subpopulations based on fluorescence intensity. After sorting, the individual populations were held at 4 degrees C to prevent further spontaneous upregulation, concentrated by centrifugation, and assayed for FPR levels. Under a variety of conditions, FPR levels correlated with Mac-1 (CD11b) expression on cell populations selected on the basis of CD11b fluorescence intensity. Analysis of subcellular fractions obtained from disrupted neutrophils before and after upregulation provided additional support for the hypothesis that Mac-1 and FPR are colocalized within a readily accessible subset of neutrophil granules.

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Graves, V., T. Gabig, L. McCarthy, EF Strour, T. Leemhuis, and D. English. "Simultaneous mobilization of Mac-1 (CD11b/CD18) and formyl peptide chemoattractant receptors in human neutrophils [published erratum appears in Blood 1993 Mar 15;81(6):1668]." Blood 80, no. 3 (1992): 776–87. http://dx.doi.org/10.1182/blood.v80.3.776.bloodjournal803776.

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Mobilization of a distinct subset of specific granules provides a physiologically important mechanism to recruit Mac-1 (CD11b/CD18) from an intracellular pool to the external surface of the neutrophil plasma membrane, where the functionally active heterodimer mediates several adherence-dependent processes that are crucial for adequate host defense and cellular inflammatory responses. We observed similar characteristics for translocation of Mac-1 and neutrophil formyl peptide receptors (FPR) and hypothesize that the readily accessible pools of both Mac-1 and FPR are colocalized within this specific granule subset. Plasma membrane levels of both FPR (assessed with 3H- FMLP) and Mac-1 (assessed by fluorescence-activated cell sorter analysis of fluorescein isothiocyanate [FITC]-Mo-1-labeled cells) were markedly downregulated in cells prepared at low temperature from blood cooled to 4 degrees C immediately after removal from the circulation. Levels of both FPR and Mac-1 remained low on cells held at 4 degrees C. Upon warming, spontaneous upregulation of Mac-1 and FPR occurred with similar kinetics and temperature dependency. Translocation of both Mac- 1 and FPR was markedly potentiated by exposure of cells to either fluoride ion (which has been shown by others to specifically elicit exocytosis of gelatinase-rich and vitamin B-12 binding protein-poor granules) or granulocyte-macrophage colony-stimulating factor (GM-CSF), a cytokine that markedly potentiates the neutrophils' host defense capabilities. Levels of both FPR and Mac-1 on F-- or GM-CSF-treated neutrophils exceeded those present on cells incubated at 37 degrees C for extended time intervals, indicating that stimulated translocation may involve mobilization of an additional granule subset. Scatchard analysis showed that only low-affinity FPR were translocated during spontaneous and stimulus-dependent upregulation. To directly compare FPR levels on the surface of cells displaying varying levels of Mac-1 within a single cell suspension, cells were labeled with FITC-Mo-1 and sorted into subpopulations based on fluorescence intensity. After sorting, the individual populations were held at 4 degrees C to prevent further spontaneous upregulation, concentrated by centrifugation, and assayed for FPR levels. Under a variety of conditions, FPR levels correlated with Mac-1 (CD11b) expression on cell populations selected on the basis of CD11b fluorescence intensity. Analysis of subcellular fractions obtained from disrupted neutrophils before and after upregulation provided additional support for the hypothesis that Mac-1 and FPR are colocalized within a readily accessible subset of neutrophil granules.

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Journal articles on the topic 'Low-MAC'

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