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Query: UMLS:C0026916 (MAC)
 5,226 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We report the results of constant temperature and pressure molecular dynamics calculations carried out on the liquid crystal (Lalpha) phase of dipalmitoylphosphatidylcholine with a mole fraction of 6.5% halothane (2-3 MAC). The present results are compared with previous simulations for pure dipalmitoylphosphatidylcholine under the same conditions (Tu et al., 1995. Biophys. J. 69:2558-2562) and with various experimental data. We have found subtle structural changes in the lipid bilayer in the presence of the anesthetic compared with the pure lipid bilayer: a small lateral expansion is accompanied by a modest contraction in the bilayer thickness. However, the overall increase in the system volume is found to be comparable to the molecular volume of the added anesthetic molecules. No significant change in the hydrocarbon chain conformations is apparent. The observed structural changes are in fair agreement with NMR data corresponding to low anesthetic concentrations. We have found that halothane exhibits no specific binding to the lipid headgroup or to the acyl chains. No evidence is obtained for preferential orientation of halothane molecules with respect to the lipid/water interface. The overall dynamics of the lipid-bound halothane molecules appears to be reminiscent of that of other small solutes (Bassolino-Klimas et al., 1995. J. Am. Chem. Soc. 117:4118-4129).
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PMID:Effects of anesthetics on the structure of a phospholipid bilayer: molecular dynamics investigation of halothane in the hydrated liquid crystal phase of dipalmitoylphosphatidylcholine. 978 6

Timed-pregnant CD-1 outbred albino Swiss mice received either methacrylamide (MAC; 0, 60, 120, or 180 mg/kg/day) or N,N'-methylenebisacrylamide (BAC; 0, 3, 10, or 30 mg/kg/day) p.o. in distilled water on gestational days (GD) 6 through 17. Maternal clinical status was monitored daily. At termination (GD 17), confirmed-pregnant females (27-30 per group, MAC; 24-25 per group, BAC) were evaluated for clinical status and gestational outcome; live fetuses were examined for external, visceral, and skeletal malformations. For MAC, no treatment-related maternal mortality was observed. Maternal body weight on GD 17, maternal weight gain during treatment and gestation, and corrected maternal weight gain were reduced at the high dose. Relative maternal food and water intake was not adversely affected; neurotoxicity was not observed. Relative maternal liver weight was increased at > or = 120 mg/kg/day; gravid uterine weight was decreased at 180 mg/kg/day. The maternal no-observed adverse effect level (NOAEL) was 60 mg/kg/day. The NOAEL for developmental toxicity was also 60 mg/kg/day. At > or = 120 mg/kg/day, mean fetal body weight was reduced. At 180 mg/kg/day, increased postimplantation death per litter was observed. Morphological development was not affected. The maternal NOAEL for BAC was 10 mg/kg/day. At 30 mg/kg/day, decreased maternal body weight on GD 17, maternal body weight change during treatment and gestation, corrected maternal body weight, and gravid uterine weight were observed. Relative maternal liver weight increased at 30 mg/kg/day. The developmental NOAEL was 3 mg/kg/day BAC. Mean fetal body weight was reduced at 30 mg/kg/day. At > or = 10 mg/kg/day, an increased incidence of fetal variations (extra rib) was observed, although fetal malformation rate was unaffected. MAC and BAC were not teratogenic to Swiss mice at the doses tested. BAC was more potent than MAC in causing adverse maternal and developmental effects.
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PMID:Evaluation of the developmental toxicity of methacrylamide and N,N'-methylenebisacrylamide in Swiss mice. 1044 64

Mycobacterium avium complex (MAC) is composed of environmental mycobacteria found widely in soil, water, and aerosols that can cause disease in animals and humans, especially disseminated infections in AIDS patients. MAC consists of two closely related species, M. avium and M. intracellulare, and may also include other, less-defined groups. The precise differentiation of MAC species is a fundamental step in epidemiological studies and for the evaluation of possible reservoirs for MAC infection in humans and animals. In this study, which included 111 pig and 26 clinical MAC isolates, two novel allelic M. avium PCR-restriction enzyme analysis (PRA) variants were identified, differing from the M. avium PRA prototype in the HaeIII digestion pattern. Mutations in HaeIII sites were confirmed by DNA sequencing. Identification of these isolates as M. avium was confirmed by PCR with DT1-DT6 and IS1245 primers, nucleic acid hybridization with the AccuProbe system, 16S ribosomal DNA sequencing, and biochemical tests. The characterization of M. avium PRA variants can be useful in the elucidation of factors involved in mycobacterial virulence and routes of infection and also has diagnostic significance, since they can be misidentified as M. simiae II and M. kansasii I if the PRA method is used in the clinical laboratory for identification of mycobacteria.
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PMID:Identification of two novel Mycobacterium avium allelic variants in pig and human isolates from Brazil by PCR-restriction enzyme analysis. 1040 7

The clinical characteristics, outcome and treatment of non-tuberculous mycobacterial tenosynovitis are reviewed. From lesions localized in the hand, 10 different species of non-tuberculous mycobacteria have been reported. The most common are Mycobacterium marinum and Mycobacterium kansasii. Other less frequent organisms are Mycobacterium avium complex, Mycobacterium szulgai, Mycobacterium terrae, Mycobacterium fortuitum, Mycobacterium chelonae, Mycobacterium abscessus, Mycobacterium malmoense and Mycobacterium xenopi. The infections appear to be the result of previous trauma, surgical procedure, corticosteroid injection or non-apparent inoculation (water contamination). Immunosuppression is sometimes associated with the infections and can be considered as a risk factor. Surgical debridement and appropriate mycobacterial cultures are critical to enable diagnosis and appropriate management. Specimens should be inoculated on a range of media and incubated at a range of temperatures in order to isolate mycobacteria with different growth characteristics (with prolonged incubation). The optimal treatment of these infections is discussed.
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PMID:Non-tuberculous mycobacterial tenosynovitis: a review. 1048 48

The anti-tumour effects and mechanism of action of combretastatin A-4 and its prodrug, combretastatin A-4 disodium phosphate, were examined in subcutaneous and orthotopically transplanted experimental colon tumour models. Additionally, the ability of these compounds to directly interfere with endothelial cell behaviour was also examined in HUVEC cultures. Combretastatin A-4 (150 mg kg(-1), intraperitoneally (i.p.)) and its water-soluble prodrug (100 mg kg(-1), i.p.) caused almost complete vascular shutdown (at 4 h), extensive haemorrhagic necrosis which started at 1 h after treatment and significant tumour growth delay in MAC 15A subcutaneous (s.c.) colon tumours. Similar vascular effects were obtained in MAC 15 orthotopic tumours and SW620 human colon tumour xenografts treated with the prodrug. More importantly, in the orthotopic models, necrosis was seen in vascularized metastatic deposits but not in avascular secondary deposits. The possible mechanism giving rise to these effects was examined in HUVEC cells. Here cellular networks formed in type I calf-skin collagen layers and these networks were completely disrupted when incubated with a non-cytotoxic concentration of combretastatin A-4 or its prodrug. This effect started at 4 h and was complete by 24 h. The same non-cytotoxic concentrations resulted in disorganization of F-actin and beta-tubulin at 1 h after treatment. In conclusion, combretastatin A-4 and its prodrug caused extensive necrosis in MAC 15A s.c. and orthotopic colon cancer and metastases, resulting in anti-tumour effects. Necrosis was not seen in avascular tumour nodules, suggesting a vascular mechanism of action.
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PMID:In vivo and in vitro evaluation of combretastatin A-4 and its sodium phosphate prodrug. 1060 28

Organisms of the Mycobacterium avium complex are common pathogens in immunosuppressed patients such as individuals with AIDS. There is evidence that in AIDS patients, the main route for M. avium infection is the gastrointestinal tract. The stomach is a formidable barrier to pathogens and the ability to resist exposure to pH lower than 3 has been shown to be a virulence determinant of enteric pathogens. Incubation of three clinical isolates of M. avium under acidic pH revealed resistance of M. avium grown both to the exponential and stationary phase at pH 2.2 for 2 h. Inhibition of protein synthesis had no effect on the acid tolerance. When the duration of the incubation at pH 2.2 was extended to 24 h, bacteria grown to the stationary phase had a significantly greater tolerance to acid than exponential phase bacteria. M. avium incubated with acid in the presence of water was significantly more resistant to pH 2.2 than M. avium in the presence of buffer. Pre-adaptation in water prior to exposure to acidic conditions was also associated with increased resistance to pH 2.2. Isoosmolarity of Hank's balanced salt solution appears to be responsible for the impaired resistance to acid between 2 and 24 h of incubation. These findings indicate that M. avium is naturally tolerant to pH<3 and that pre-adaptation under conditions similar to the conditions where M. avium is found in the environment results in increased acid resistance.
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PMID:Mycobacterium avium resists exposure to the acidic conditions of the stomach. 1061 29

A free diazafluorenyl radical based on the Koelsch free radical was designed and synthesized with expectations of stability and water solubility. The novel radical precursors were synthesised from the parent brominated stilbene and the substituted fluorenes in an IPSO substitution, as a key synthetic step. The precursors were deprotonated and the anion was discharged by an aqueous solution of potassium cyanoferrate. The new radicals were prepared from fluorene in 6 steps with good overall yields. These radicals have shown promising anticancer activity in initial screenings on 2 different MAC cell lines.
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PMID:Design and synthesis of stable, water soluble radicals as potential anti-cancer agents. 1062 65

We tested the hypothesis that the pressure exerted by the laryngeal mask airway (LMA) against the pharyngeal mucosa varied with neuromuscular block, mode of ventilation and the respiratory cycle. We studied 20 anaesthetized adult patients. Microchip sensors were attached to a size 5 LMA at locations approximately corresponding to the base of the tongue, hypopharynx, lateral pharynx, oropharynx, posterior pharynx and piriform fossa. Mucosal pressures were measured with an intracuff pressure of 60 cm H2O under four conditions during anaesthesia using 2.0 MAC of sevoflurane: (1) apnoeic, non-paralysed; (2) spontaneously breathing, non-paralysed; (3) ventilated, paralysed and (4) non-ventilated, paralysed. In conditions (2) and (3), mucosal pressures were measured at the end of inspiration and expiration. Mean mucosal pressure was less than 10 cm H2O at all locations. There were no significant changes in mucosal pressure at any location between the four conditions. There was no variation between inspiration and expiration. With an intracuff pressure of 60 cm H2O in these circumstances, mucosal pressures were much less than considered safe for prolonged tracheal intubation.
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PMID:Influence of neuromuscular block, mode of ventilation and respiratory cycle on pharyngeal mucosal pressures with the laryngeal mask airway. 1065 26

Avian tuberculosis is an animal disease notifiable for statistical purposes in Germany. Cases notified (between 130 and 230 annually) were primarily related to private flocks of pedigree poultry and layers consisting of less than 20 animals and individual animals in game enclosures and zoological gardens. Mycobacterium (M.) avium infection does not play any role in modern intensive poultry husbandry. Human M. avium infections have considerably gained in importance in the last two decades, mainly in HIV-infected patients. Due to the ubiquitous character of MAIC (Mycobacterium avium intracellulare-Complex), it is difficult to establish confirmed epidemiological associations with infections in humans. Surface and drinking water, soil and also foods as well as direct contact with infected birds (pet birds) have been discussed as possible sources of infection. Recently, strains of the serovars 1, 2 and 3 which have often been isolated from birds (bird-type strains) could be defined as a taxon on its own right among MAIC by using molecular-biological methods for MAIC typing (RFLP--restriction fragment length polymorphism and PFGE-pulsed field gel elektrophoresis). In exceptional cases only, strains of this character have been isolated from humans. Consequently, poultry-to-man transmission of M. avium appears to be a very improbable event. In contrast, extensive conformity has been found to exist between M. avium isolates of human origin and isolates from pigs. This fact has rightly given rise to assumptions of either the presence of epidemiological links between pigs and humans or of infection from common sources. In a summarizing view, it can be stated that M. avium infection of farm poultry is hardly of any importance for poultry production as well as for human disease. The importance of MAIC for infections in other farm animals (cattle and swine) is outlined and discussed.
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PMID:[Mycobacterium avium infections in poultry--a risk for human health or not?]. 1074 34

The Mycobacterium avium complex (MAC) comprises a heterogeneous group of slowly-growing mycobacteria that are pathogenic for both humans and animals. Two genetically distinct species within MAC are M. avium, which tends to infect HIV-infected patients, and M. intracellulare more common among immunocompetent individuals. Contrary to M. intracellulare which relates to a single species, M. avium is separated into three subspecies; M. avium subsp. avium, a major opportunistic pathogen leading to a disseminated disease among terminal AIDS patients; M. avium subsp. paratuberculosis, causing Johne's disease among ruminants and implicated in Crohn's disease among humans; and M. avium subsp. silvaticum, a pathogen affecting birds that may cause chronic enteritis among calves but has not yet been associated with human disease. With the exception of mycobactin-dependent growth of M. paratuberculosis, most of the biochemical and cultural tests cannot discriminate among the three subspecies of M. avium. However, recently developed molecular methods and fingerprinting of strains using insertion sequences allows not only to distinguish among them but also further to explore the polymorphism of human and animal isolates. Numerous studies have underlined the probable role of various ecological niches (water, dust, soil, pigs, poultry and ruminants etc.) as a possible source of contamination for AIDS patients. This paper reviews the phenotypic and genotypic markers and epidemiology of M. avium complex organisms and current knowledge of the molecular basis of of inter-species transmission.
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PMID:[Mycobacterium avium-intracellulare complex: phenotypic and genotypic markers and the molecular basis for interspecies transmission]. 1103 55


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