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Biomedical subjects

J Lewis

Publications and source records attributed to J Lewis.

At least 199 records · Page 11Linked to original sources
PubMed1995

Primary neurogenesis in Xenopus embryos regulated by a homologue of the Drosophila neurogenic gene Delta.

X-Delta-1, a Xenopus homologue of the Drosophila Delta gene, is expressed in the early embryonic nervous system in scattered cells that appear to be the prospective primary neurons. Ectopic X-Delta-1 activity inhibits production of primary neurons and interference with endogenous X-Delta-1 activity results in overproduction of primary neurons. These results indicate that the X-Delta-1 protein mediates lateral inhibition delivered by prospective neurons to adjacent cells, and that commitment to a neural fate in vertebrates is regulated by Delta-Notch signalling as in Drosophila.

Animals↗
PubMed1995

Expression of a Delta homologue in prospective neurons in the chick.

The product of the Delta gene, acting as ligand, and that of the Notch gene, acting as receptor, are key components in a lateral-inhibition signalling pathway that regulates the detailed patterning of many different tissues in Drosophila. During neurogenesis in particular, neural precursors, by expressing Delta, inhibit neighbouring Notch-expressing cells from becoming committed to a neural fate. Vertebrates are known to have several Notch genes, but their functions are unclear and their ligands hitherto unidentified. Here we identify and describe a chick Delta homologue, C-Delta-1. We show that C-Delta-1 is expressed in prospective neurons during neurogenesis, as new cells are being born and their fates decided. Our data from the chick, combined with parallel evidence from Xenopus, suggest that both the Delta/Notch signalling mechanism and its role in neurogenesis have been conserved in vertebrates.

Amino Acid Sequence↗
PubMed1995

Biopsychosocial changes associated with cessation of cannabis use: a single case study of acute and chronic cognitive effects, withdrawal and treatment.

A 35 year old male was cognitively assessed prior to cessation of 18 years of daily cannabis use and monitored for several weeks post cessation. Brain event-related potential (ERP) measures of selective attention reflecting a difficulty in filtering out complex irrelevant information showed no indication of improvement over 6 weeks of abstinence. In contrast, when tested in the acutely intoxicated state prior to cessation of use, a dramatic normalisation of the ERP signature of this individual was observed. A treatment program based on supportive-expressive psychotherapy was administered and depression, anxiety and general psychological health were monitored over the course of withdrawal from cannabis.

Action Potentials↗
PubMed1995

Protective measure use and symptoms among agropesticide applicators in Sri Lanka.

Sri Lankan farmers use large amounts of pesticides to control the pests affecting their vegetable crops. Improper use of pesticides by farmers has resulted in poisoning of occupational origin. This paper examines the use of protective measures by pesticide applicators and its relationship to their illness symptoms. The data were collected by interviewing a stratified random sample of 150 farmers from predominantly vegetable growing areas of the Matale district during 1990/91 using structured questionnaires. These data were supplemented with secondary data and observation of all stages of pesticide application. Scales were constructed to measure the domains of material style of life, awareness and use of protective measures, and illness symptoms experienced by pesticide applicators. It was found that most of the farmers were aware of the protective measures to be used when applying pesticides. There was, however, no significant positive relationship between awareness and use of protective measures. The main reason for not using protective measures was discomfort. The most common symptoms reported by pesticide applicators were faintish feeling, headache and dizziness. A significant negative relationship was observed between use of protective measures and symptoms exhibited within four hours of application. It is recommended that protective materials adapted to the climate and socio-economic conditions of farmers be developed, and that farmers be encouraged to use these protective materials through appropriate educational efforts and incentives.

Adult↗
PubMed1995

The prevalence and prophylaxis of gout in England.

The prevalence of gout in England was reported as having nearly doubled in the 1970s to about 3 per 1000, and it is possible that it has continued to increase. There may also have been some change in the level of prophylactic therapy compared with the 44.8% recorded in 1979. In this study, data were provided from their morbidity registers by 40 volunteer practices with a combined population of over 300,000 patients. Analyses of prevalence by age and sex, and of the extent of prophylaxis were made. The male:female ratio and the increase with age found were in line with earlier work, but overall prevalence was much higher at almost 10 per 1000. There was considerable inter-practice variation: 20% of this could be accounted for by the age and sex structure of the practice populations, but neither economic status nor broad geographical factors appeared to be significant, and it did not appear to be due to variation between practices in the level of special interest in gout. Prophylactic therapy--almost entirely allopurinol--was being prescribed for 48% of the sufferers; though practices varied widely in their propensity to give it, as a group the amount of allopurinol they used was close to the national average. The increase found in the prevalence of gout may be related to an increase in obesity in the population.

Adult↗
PubMed1995

Family provision of health and welfare in the mixed economy of care in the late nineteenth and twentieth centuries.

The paper begins by discussing the place of the family as a provider of welfare in the context of the changing nature of the 'mixed economy of welfare'. It goes on to explore the nature of social provision by the family at the turn of the century, stressing the way in which the behaviour of people within families was taken as the test of citizenship in an ethical state, and was therefore made the target of volumtary and state intervention. The paper concludes by contrasting this with ideas about family responsibility in the late twentieth century, and the concern to promote family provision as an alternative to state provision.

Family Health↗
PubMed1995

Regulation of transgenic class II major histocompatibility genes in murine Langerhans cells.

I-E is a class II major histocompatibility complex molecule normally expressed by Langerhans cells. A series of transgenic mice were developed previously that carry E alpha d gene constructs with promoter-region deletions that cause expression of I-E by different cell types when maintained on a B6 (I-E[-]) genetic background. To study cis-acting gene sequences that regulate expression of class II proteins by Langerhans cells, we identified transgenic I-E expression by tissue immunoperoxidase staining and by epidermal cell suspension immunofluorescence cytometry. Mice with a transgene containing 1.4 kilobase pairs (kb) of flanking sequence 5' to the E alpha initiation site expressed barely detectable levels of I-E on a tiny percentage of Langerhans cells, indicating that sequences promoting Langerhans cell expression of E alpha exist between 2.0 and 1.4 kb 5' of the E alpha initiation site. Removal of an additional 170 bp of 5' flanking sequence caused near-normal levels of expression by approximately one third of epidermal Langerhans cells, which contrasts with studies that showed minimal transgene expression by splenic dendritic cells in these animals. Thus, sequences between 1.4 and 1.23 kb 5' of the E alpha initiation site decrease expression of I-E by epidermal Langerhans cells, but enable I-E expression by splenic dendritic cells. These studies identify Langerhans cell-specific regulatory sequences and genetic regions controlling major histocompatibility complex class II gene expression in Langerhans cells and splenic dendritic cells. The genetic regions identified may be particularly important because differential regulation of class II major histocompatibility complex protein synthesis by Langerhans cells and dendritic cells may be crucial to immune functions of intact animals.

Animals↗
PubMed1995

Isolation and characterization of a beta-D-glucuronidase-producing strain of Escherichia coli serotype O157:H7 in the United States.

A phenotypic variant of Escherichia coli serotype O157:H7 (G5101) was isolated from a patient with bloody diarrhea. Strain G5101 does not ferment sorbitol but is beta-D-glucuronidase and urease positive. Serotyping and colony hybridization using a serotype-specific DNA probe confirmed that the isolate was O157:H7. G5101 produces Shiga-like toxins I and II and contains an eae gene that is highly conserved in the O157:H7 serotype. This strain would have been missed by laboratories that screen for the sorbitol-negative, beta-D-glucuronidase-negative phenotype in isolating E. coli O157:H7 from clinical and food specimens.

DNA Probes↗
PubMed1995

The Mini Mental State Exam as a predictor of neuropsychological functioning after cardiac surgery.

OBJECTIVE: The present longitudinal study was designed to: 1) determine the ability of the Mini Mental State Exam (MMSE) to predict neuropsychologic impairment based on neuropsychologic testing five to seven days and six weeks after cardiac surgery; and 2) to determine whether the traditional or the education-related MMSE norms are more appropriate to use for this purpose. METHOD: The day before surgery (T1), before hospital discharge (T2), and six weeks after surgery (T3), 247 subjects completed a battery of five neuropsychologic tests. Subjects also completed the Center for Epidemiological Studies Depression Scale and the Speilberger State-Trait Anxiety Inventory. Subjects completed the MMSE two to three days after surgery. RESULTS: Stepwise regression analyses revealed that the MMSE significantly predicted only a small portion of the variance in neuropsychologic test performance at T2, and to an even lesser extent at T3, over and above the demographic variables. In assessing the association between an impairment score (derived from the neuropsychologic test battery) and the MMSE, we found that the traditional MMSE cut-off score maximized specificity (number of true negatives) while the education-adjusted MMSE cut-off scores maximized sensitivity (number of true positives). CONCLUSIONS: These results suggest that although the MMSE is widely used to assess cognitive mental status, it may have limited value in identifying patients with cognitive impairment post-cardiac surgery, and special attention must be paid to the cut-off scores used in interpreting the MMSE.

Adult↗
PubMed1995

TB exposure: are you prepared?

1. The elderly have the highest case rates for TB disease. 2. Residents need to be screened for TB infection on admission with a Mantoux skin test. 3. Employees need to be screened for TB by the Mantoux skin test on hire and annually. 4. A chest x-ray is not adequate to screen for TB infection.

Humans↗
PubMed1995

Clerkship rotation in rural family practice.

Every medical student at Memorial University of Newfoundland must do a rotation in rural family practice. This paper describes the organization of this clerkship learning experience and discusses its possible influence upon career choice.

Career Choice↗