PubMed Health⌕ Search

Biomedical subjects

E Mason

Publications and source records attributed to E Mason.

68 records · Page 4Linked to original sources
PubMed1978

Kinetics of hydrolysis of dispersions of saturated phosphatidylcholines by Crotalus atrox phospholipase A2.

Dispersions of lamellar phase dipalmitoyl phosphatidylcholine (DDPC) and dimyristoyl phosphatidylcholine (DMPC) in 0.01 M CaCl2 were subjected to hydrolysis by phospholipase A2 (EC 3.1.1.4) from Crotalus atrox venom. The reaction was followed continuously by titrating the released fatty acids. For hydrolysis of gel phase phosphatides, the steady-state initial velocities were hyperbolic functions of bulk lipid concentrations. At the 'pre-transition' temperature (34 degrees C for DPPC, 15 degrees C for DMPC), there was a large increase in the Michaelis parameter Vmax but no change in the parameter Km. A model was devised to account for these observations, in which the enzyme desorbs from the lipid surface after hydrolysis. The desorption rate constant is postulated to increase above the pretransition temperature. For hydrolysis of liquid crystalline phosphatides, the reaction consisted of a short initial burst of hydrolysis, a long 'lag' period of very slow reaction, followed by a dramatic increase in the reaction rate. Addition of 10 mol% lysolecithin or fatty acid abolished the 'lag' period. It was postulated that the enzyme adsorbs irreversibly to the surface of the liquid crystalline phase. Reaction products are postulated to stimulate desorption of enzyme from the surface. Thus, temperature-dependent changes in the rate of hydrolysis of dispersed phosphatidylcholines are attributed to changes in the rate of desorption of the enzyme from the lipid surface.

Chemical Phenomena↗
PubMed1977

Heat-stable enterotoxigenic Escherichia coli and necrotizing enterocolitis: lack of an association.

During an outbreak of diarrhea in a special care nursery caused by heat-stable enterotoxigenic Escherichia coli (serotype 078:H11:K80), nine (4.3%) of the 205 infants in the nursery developed necrotizing enterocolitis. Cases of necrotizing enterocolitis were not significantly more common in infants colonized or infected with these organisms; heat-stable enterotoxigenic E. coli was isolated from 5(56%) of nine cases of necrotizing ecterocolitis and from 27(38%) of the 71 infants without necrotizing enterocolitis who were also cultured. Our findings suggest that caution should be taken in implicating enterotoxigenic E. coli as a cause of necrotizing enterocolitis.

Animals↗
PubMed1976

Infantile diarrhea produced by heat-stable enterotoxigenic Escherichia coli.

Between December, 1974, and August 1975, intestinal illness occurred in 55 of 205 infants admitted to the special-care nurseries of a large children's hospital. Escherichia coli serotype 078:K80:H12, which produced a heat-stable enterotoxin, was isolated from 18 of 25 symptomatic infants as compared with 14 of 55 asymptomatic infants (P less than 0.001). Colistin administered prophylactically to 24 culture-negative asymptomatic infants did not prevent colonization in 10, whereas colonization did occur in 22 of 56 not receiving colistin (P = 1.0). This outbreak provides laboratory and epidemiologic evidence that heat-stable enterotoxigenic Esch. coli is pathogenic in human beings and produces infantile diarrhea.

Adult↗
PubMed1971

Isoniazid acetylation rates (phenotypes) of patients being treated for tuberculosis.

Isoniazid therapy could be used more rationally if patients' isoniazid acetylation rates were known. To explore the clinical usefulness of a recently described simple method for acetylator phenotyping, acetylated and free isoniazid were measured semiquantitatively in morning urine specimens from sanatorium in-patients being treated with the drug. The distribution of acetylisoniazid: isoniazid ratios was bimodal. The ratios thus identify rapid and slow acetylators of isoniazid, without disturbing their routine or their therapy. Ratios measured in samples from control subjects who had received a single dose of isoniazid did not discriminate between these phenotypes, and urine from diabetic patients gave false reactions.

Humans↗
PubMedDate not supplied

Epidemiological features of epidemic cholera (El Tor) in Zimbabwe.

Epidemics of cholera have been frequent in southern Africa since the reintroduction of the disease to the continent in 1970. In late 1992, following a severe drought and an influx of refugees from Mozambique, cholera reappeared in Zimbabwe for the first time since 1985 and rapidly spread through the rural areas of the country. Data relating to symptomatic cholera infection collected during 2 large outbreaks on the eastern border of the country showed that host age and sex were important factors relating to symptomatic infection, as were population density and access to water. Epidemic profiles for the 2 study areas differed in that one of the profiles exhibited a distinct second phase epidemic. This unusual pattern was compared qualitatively with the output of a series of simple mathematical models to examine the contribution of different epidemiological processes to the pattern of disease observed. Model output suggested a complex disease process, in which the dynamics may have been influenced by spatial components. Statistical analysis of these unusual data showed that the observed pattern was independent of the effects of host age or sex, and provided compelling evidence of a marked spatial component of the second phase epidemic.

Adolescent↗
PubMedDate not supplied

Factors affecting substance abuse treatment completion for women.

Substance abuse by women is considered an individual pathology, and the larger social processes of recovery are seldom explored. This research study examined social factors that influenced completion of an outpatient women-centered substance abuse treatment program. The treatment records of a group of 15 women who completed the program were compared with a group who did not complete the program. More completers had previous life successes in the areas of education, job skills, and employment history. Completers also had fewer children, less involvement with child protective services, and lower levels of chaos, a construct that included the presence of two of any of the following in women's lives: child protective services, homelessness, psychiatric diagnosis, or domestic violence. Completion of substance abuse treatment seems more likely for women with personal and social resources. If programs are to be successful, adequate funding must be provided for both assessment and support of the social problems encountered by the most vulnerable women.

Adult↗
PubMedDate not supplied

Field efficiency of syphilis screening in antenatal care: lessons from Gutu District in Zimbabwe.

OBJECTIVES: To determine coverage for antenatal syphilis screening in a rural area and evaluate the accuracy of on-site Rapid Plasma Reagin (RPR) tests performed by nurse-midwives. DESIGN: Descriptive cross sectional. SETTING: Rural Health Centres (n = 23) in the Gutu District of Zimbabwe. SUBJECTS: Women booking for antenatal care in the district were used to determine coverage of screening. Results from women who had an RPR test performed during a nine week period were used in assessing the accuracy of tests performed by nurse-midwives. INTERVENTION: On-site antenatal screening for syphilis using an RPR kit with immediate results and treatment for women who tested positive. MAIN OUTCOME MEASURES: Prevalence of syphilis (positive RPR) at booking and the level of agreement between three observers (RHC nurse-midwife, medical practitioner under field conditions and medical laboratory technologist). RESULTS: Eighty five percent of women were screened for syphilis at the first antenatal visit and 11% had a positive RPR. Almost all (97.3%) women with a positive RPR test result were treated. The accuracy of tests performed by RHC staff was poor with a sensitivity of 40% (95% CI 21.8 to 61.1) when compared to those done by the medical practitioner and 8.7% (95% CI 1.5 to 29.5) when compared to those done in a laboratory. The predictive value of a positive test was 22.7% and that of a negative test was 94.9%. CONCLUSION: The coverage of screening for syphilis in pregnant women in Gutu District was good but the results were unreliable. There is need for nurse-midwives, who perform the majority of RPR tests in the RHC, to receive adequate training to ensure competence in testing and to strengthen quality control procedures.

Antibodies, Bacterial↗
PubMedDate not supplied

Are primary care residents adequately prepared to care for women of reproductive age?

A 1991 study of 115 internal medicine and 28 family practice residents at a large inner-city public hospital finds that both groups would perform poorly in providing preconception counseling to women of reproductive age. More than 40% of residents failed to indicate that they would provide a healthy woman with information on rubella immunization and family planning or counseling on sexually transmitted diseases and safer sex. When counseling a diabetic woman seeking pregnancy, 74% would not have discussed congenital anomalies with her and 45% would not have considered discontinuing oral hypoglycemics if she became pregnant. Furthermore, 58% would have neglected to review or change hypertension medications in a newly diagnosed pregnant woman. Although both internal medicine and family practice residents had positive attitudes toward offering preconception care, family practice residents had significantly higher attitude scores. No clear improvement was found in patient management, attitude or knowledge scores as residents progressed from their first to their third year of training.

Adult↗