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Biomedical subjects

M Warren

Publications and source records attributed to M Warren.

At least 55 records · Page 3Linked to original sources
PubMed1991

The vacuolar H(+)-translocating ATPase of renal tubules contains a 115-kDa glycosylated subunit.

Kidney microsomes were fractionated with Triton X-114, to give a fraction enriched in the renal tubule H(+)-translocating ATPase, as judged by the sensitivity of its ATPase activity to bafilomycin A1, and its content of two polypeptides recognized by antibodies directed against subunits of plant tonoplast ATPases. This fraction contained a polypeptide of apparent molecular mass of 115 kDa, that was recognized by an antibody to the largest (120 kDa) subunit of chromaffin-granule membrane H(+)-ATPase, and, like this subunit, was reduced in molecular weight on treatment with glycopeptidase F. We conclude that, like other mammalian vacuolar H(+)-ATPases, the kidney H(+)-ATPase contains a large, glycosylated subunit.

Adrenal Gland Neoplasms↗
PubMed1991

Comparison of two commercial kits for identifying and biotyping Haemophilus parainfluenzae.

The Minitek system and the more recently introduced Micro Scan HNID panels for the identification and biotyping of 98 V dependent Haemophilus isolates were compared. Identical results were obtained for 77 isolates. The discrepancy in the results of ornithine and urease was accounted for mainly by the mismatching of the identification by the two kits. When 13 isolates of H parainfluenzae with mismatched biotypes were re-examined, the results from Micro Scan correlated with 92% of those obtained by Christensen's urea broth and 100% by the ornithine test (Lab M); the corresponding figures for Minitek were 61% and 30%, respectively. Micro Scan was easy to handle on the bench and results were ready on the same day. These results suggest that further work is required to assess these two systems for the biotyping of H parainfluenzae.

Bacterial Typing Techniques↗
PubMed1990

Identification of visual scanning deficits in adults after cerebrovascular accident.

Visual scanning deficits can result in the inefficient acquisition of information about one's environment. For adults who have had cerebrovascular accidents (CVAs), such deficits can interfere with the independent performance of many daily activities. The present study examined five tests designed to measure visual scanning deficits in post-CVA adults. Subjects with right and left hemisphere lesions were matched with control subjects by age and sex, and their performances on the tests were compared. The difference between the matched groups was statistically significant for all tests, with the hemiplegic subjects achieving lower scores than their normal counterparts. Deficits in visual scanning speed, identification of visual stimuli in the hemifield on the involved side, use of a systematic scanning pattern, and the ability to reproduce accurate visual designs were identified in the hemiplegic group. Statistically significant correlations were obtained on test-retest and interrater data, which indicates that the tests are reliable measures. The results of this study show that visual scanning deficits are present in post-CVA patients and can be measured with simple clinical evaluations. The presence of scanning deficits may significantly interfere with performance on tests measuring higher level visual-perceptual skills such as visual closure, figure-ground perception, and visual memory. An accurate assessment of visual-perceptual skills cannot be made without prior evaluation of such basic oculomotor functions as scanning. This approach is consistent with the developmental framework applied to most areas of treatment with brain-injured adults but is one that traditionally has not been applied in the evaluation of visual-perceptual skills.

Activities of Daily Living↗
PubMed1989

Molecular cloning of resistance genes and architecture of a linked gene cluster involved in biosynthesis of oxytetracycline by Streptomyces rimosus.

The isolation of mutants of Streptomyces rimosus which were blocked in oxytetracycline (OTC) production was described previously. The genes for the early steps of antibiotic biosynthesis mapped together. Genomic DNA fragments of S. rimosus which conferred resistance to OTC and complemented all of these non-producing mutants have been cloned. The cloned DNA is physically linked within approximately 30 kb of the genome of S. rimosus. The gene cluster is flanked at each end by a resistance gene each of which, independently, can confer resistance to the antibiotic. In OTC-sensitive strains of S. rimosus, the entire gene cluster including both resistance genes has been deleted. Complementation of blocked mutants by cloned DNA fragments in multi-copy vectors was often masked by a secondary effect of switching off antibiotic production in strains otherwise competent to produce OTC. This adverse effect on OTC production was not observed with recombinants using low copy-number vectors.

Cloning, Molecular↗
PubMed1989

Cloning and heterologous expression in Streptomyces lividans of Streptomyces rimosus genes involved in oxytetracycline biosynthesis.

The anhydrotetracycline (ATC) oxygenase enzyme which carries out the conversion of ATC to dehydrotetracycline was purified and the N-terminal amino acid sequence was determined. The sequence displays a significant similarity to that of the p-hydroxybenzoate hydroxylase from Pseudomonas fluorescens. This is consistent with the activity of the oxygenase, i.e., addition of a hydroxyl moiety to an aromatic ring structure. Oligonucleotide probes were designed and used to clone the corresponding fragment of chromosomal DNA from Streptomyces rimosus. This DNA fragment was used to screen a cosmid library, allowing the isolation of flanking DNA sequences. Surprisingly, the gene was located within the previously cloned cluster of genes involved in the synthesis of the biosynthetic intermediate ATC and not as had been expected (P. M. Rhodes, N. Winskill, E. J. Friend, and M. Warren, J. Gen. Microbiol. 124:329-338, 1981) at a separate locus on the other side of the chromosome. Subcloning of an appropriate DNA fragment from one of the cosmid clones onto pIJ916 produced Streptomyces lividans transformants which synthesized oxytetracycline.

Amino Acid Sequence↗
PubMed1988

Influence of medium composition on 7-alkoxycoumarin O-dealkylase activities of rat hepatocytes in primary maintenance culture.

1. The activities of 7-methoxycoumarin (7-MCOD), 7-ethoxycoumarin (7-ECOD) and 7-propoxycoumarin (7-PCOD) O-dealkylases decreased by 75-90% during culture of rat hepatocytes for 72 h. 2. The addition of dexamethasone (D) produced a stabilization or modest enhancement of 7-ECOD and 7-PCOD activities depending on the medium used; D was without effect on 7-MCOD activity. 3. The addition of nicotinamide (N) produced some stabilization of 7-ECOD and 7-PCOD activities but not of 7-MCOD activity. 4. The addition of D + N was associated with large increases in 7-ECOD and 7-PCOD activities, again with little effect on 7-MCOD activity. 5. Ethoxyresorufin O-dealkylase activity correlated with 7-ECOD/7-PCOD activities, whereas pentoxyresorufin O-dealkylase activity correlated with 7-MCOD activity. 6. It is concluded that D exerts a selective effect on certain forms of cytochrome P-450, but that more than one mechanism is probably implicated in this effect. 7. The magnitudes of induction of 7-ECOD activity by phenobarbitone and beta-naphthoflavone were blunted when cells were treated in culture when compared to treatment in vivo; the presence of D in the culture medium did not modify this phenomenon.

7-Alkoxycoumarin O-Dealkylase↗
PubMed1988

Extent of DNR policies varies across healthcare settings.

A cross-section random survey of acute care hospitals, psychiatric hospitals, long-term care facilities, and hospices was conducted in 1986 to determine the extent of use, the nature, and the implementation of do-not-resuscitate (DNR) policies. Data also were collected to identify the common problems of implementing DNR policies, as well as how conflicts in the use of DNR orders are resolved. The survey found that 30.7 percent of healthcare organizations have a formal policy, 28 percent have an informal policy, and 41.3 percent have no policy. Formal policies were found in 56.9 percent of acute care and 42.9 percent of hospice care settings, compared with 11.4 percent in psychiatric and 20.1 percent in long-term care settings. Although predictors varied across the four settings studied, formal policies were associated with larger organizations, the use of consultation, accreditation by the Joint Commission on Accreditation of Healthcare Organizations, and the presence of an ethics committee. The recognition of a living will plays a small role in the presence of a formal DNR policy. Given the growing concern of the American public and healthcare organizations over DNR orders, the implications of this study call for careful attention to DNR and related medical and ethical issues and the establishment of policies that clearly delineate when, how, and with whom such issues are discussed and resolved.

Cross-Sectional Studies↗
PubMed1986

Studies of comparative infectivity of fifteen strains of Plasmodium vivax to laboratory-reared anopheline mosquitoes, with special reference to Anopheles culicifacies.

The Sattoki strain of species A of the taxon Anopheles culicifacies Giles was infected with 15 different strains of Plasmodium vivax from Asia, New Guinea, and Central and South America. A comparison of the relative infectivity indicated a marked variation for the different strains of P. vivax when compared to Anopheles freeborni mosquitoes.

Animals↗
PubMed1985

REM sleep deprivation effect on apomorphine-induced gnawing is reversed by dexamethasone.

Glucocorticoid feedback was manipulated in rats deprived of REM for six days or left undisturbed in their home cages. One half of each group received concurrent dexamethasone (400 micrograms/kg), while the other half received corn oil. On test day, rats were observed for 5 min, injected with apomorphine (0.8 mg/kg, i.p.), and again observed. Dexamethasone revealed REM-deprivation-enhanced stereotypical gnawing, but had no effect on REM-deprivation-reduced rearing, suggesting the involvement of catecholamine depletion by non-specific stress-related factors in the former REM deprivation effect.

Animals↗
PubMed1985

Safety measures associated with the use of organophosphate insecticides in the Haitian malaria control programme.

A programme emphasizing intensive training, use of protective equipment and uniforms, daily supervision of safety measures at work, and weekly monitoring of blood cholinesterase levels by the tintometric method was instituted to prevent toxicity in Haitian malaria workers during spraying with the organophosphate insecticides fenitrothion and malathion. The programme functioned well, depressed cholinesterase activity (</= 50% of normal) being detected rapidly prior to the development of serious symptoms. Evidence of fenitrothion overexposure appeared in spraymen early in the first spray cycle, and was associated with faulty protective clothing and a failure to observe strictly the recommended safety measures at work. After these deficiencies were corrected, insecticide application continued without serious incidents or interruption of the programme. No serious reduction of cholinesterase activity was seen in a more limited study of spraymen using malathion. It is strongly recommended that similar training and monitoring programmes should be instituted whenever organophosphate pesticides are used as residual sprays for malaria control. This is particularly important in areas where the more toxic compound, fenitrothion, is to be used.

Cholinesterases↗