Search PubMed⌕ Search

Biomedical subjects

S Smith

Publications and source records attributed to S Smith.

At least 523 records · Page 29Linked to original sources
PubMed1994

Differences in the pattern visual evoked potential between pregnant and non-pregnant women.

It has been proposed that latencies of some components of the pattern-reversal visual evoked potential (PRVEP) are shorter in women than in men because of differences in levels of circulating sex steroids. Pregnancy is a time when serum levels of oestrogen and progestogen are considerably greater than in the non-pregnant state. Whole and half field PRVEP latencies and amplitudes have been compared in 16 pregnant and 38 healthy non-pregnant women. The mean P100 latencies for all responses were shorter in the pregnant women, with statistically significant differences for the left eye whole field latency (P < 0.05) and the left eye right and left half field latencies (P < 0.005 and P < 0.05, respectively) and the right eye right half field latency (P < 0.05). The latencies in women in the pregnant group showed a negative correlation with gestation, which reached statistical significance for the REWF (r = -0.55, P < 0.05). These observed differences in PRVEP latencies in pregnant and non-pregnant women and the association between latency and gestation are likely to be due to differences in circulating sex steroids, and this effect may be the principal reason for latency differences between the sexes.

Adolescent↗
PubMed1994

High dose methylprednisolone therapy in children with onyalai.

Methylprednisolone at 30 mg/kg i.v. for 3 days followed by 20 mg/kg for 4 days was given to eight children who had been referred to Windhoek State Hospital with onyalai. The history of previous attacks, change in platelet count over 7 days, blood transfusion requirement and length of clinical bleeding were compared with similar parameters in a historical control group of 21 untreated children who had been observed in hospital. All the treated patients demonstrated a rise of at least 25 x 10(9)/l in the platelet count and the mean count increased from 16 x 10(9)/l on admission to 161 x 10(9)/l on day 8. In the untreated control group, 38% of children did not demonstrate a rise in platelet count of 25 x 10(9)/l (p < 0.05) and the mean platelet count increased from 21 x 10(9)/l to 100 x 10(9)/l on day 8. The average duration of bleeding was 3.1 days in the controls versus 1.5 days in the treatment group. One-third of the children in both groups needed a blood transfusion. Total blood use amounted to 0.9 unit per child for controls and 0.5 unit per child in the treatment group. The average cost of treatment (drug only) was $US 44 per patient. High dose methylprednisolone therapy reduced the morbidity of onyalai in children in this series.

Adolescent↗
PubMed1994

Human immunoglobulin VH and D segments on chromosomes 15q11.2 and 16p11.2.

In addition to the major human immunoglobulin heavy-chain locus on chromosome 14q32.3, VH and D segments are known to be present on chromosomes 15 and 16. We have now amplified and sequenced 24 such VH segments from somatic cell hybrids and have assigned them to 15q11.2 and 16p11.2 using cosmid and yeast artificial chromosome clones. In addition, we have located a cluster of D segments on 15q11.2, previously thought to be located on 14q32.3. We propose that the segments on chromosome 16 arose by an interchromosomal duplication and identify the corresponding region on chromosome 14. Taken together with the completion of a map of the human VH locus on 14q32.3, the total number of VH segments now identified is 117. We can now account for most, if not all human germ-line VH segments.

Base Sequence↗
PubMed1994

Collaboration in distance education between nursing schools and hospitals.

Interactive television (ITV) is being used by increasing numbers of nursing schools and hospitals to provide educational access to geographically diverse learners and nurse employees. ITV-related research suggests that learner outcomes and satisfaction with such distance education courses are similar to those associated with the traditional classroom. The authors conducted an evaluation of a major nursing school's nursing telecourse program (NTP) to assess collaborative efforts with hospitals and regional campuses. The respondents, 15 site coordinators, were generally satisfied with the operational aspects of the NTP. Concerns raised by respondents included classroom space availability, operational costs, library resources, and communication equipment and processes. These stakeholders' perspectives were viewed as valuable in identifying problems and making improvements in the school's NTP.

Education, Nursing↗
PubMed1994

Adherence of group B streptococci to cultured epithelial cells: roles of environmental factors and bacterial surface components.

Group B streptococci (GBS) are the major cause of neonatal pneumonia, sepsis, and meningitis. Steps considered to be important in the pathogenesis of this infection include colonization of the rectum and vagina of the mother, aspiration of GBS into the fetal lung during or just prior to delivery, and invasion of GBS into pulmonary epithelial cells. We have previously demonstrated that GBS can invade pulmonary epithelial cells both in vivo and in vitro. Adherence of GBS to epithelial cells may play an important role in colonization of the rectum and vagina and constitute a first step in invasion of pulmonary epithelial cells. Because GBS can both adhere to and invade epithelial cells, we have developed two assays for GBS adherence which measure cell surface and not intracellular bacteria. Using these assays, we were able to demonstrate specific adherence of GBS to pulmonary epithelial cells. Adherence levels were similar at 4 and 37 degrees C and for log- and stationary-phase bacteria. Physiologic conditions vary considerably between the rectum, vagina, and lung, and a range of conditions was therefore tested. Adherence was enhanced in hypotonic solutions, while magnesium and calcium had no effect on adherence at physiologic concentrations. In comparison with adherence at neutral pH, adherence was increased 6- to 20-fold at pH 4, which is the normal vaginal pH. Neither capsular polysaccharide nor lipoteichoic acid was important for adherence in these assays. Treatment of GBS with trypsin decreased their adherence by more than 75%, indicating that surface proteins play an important role.

Bacterial Adhesion↗
PubMed1994

Crystal violet reactions of coagulase negative staphylococci.

Twenty four reference strains and 112 clinical isolates of coagulase negative staphylococci (CNS) were examined for their reactions in the crystal violet test. Some species gave a white reaction and others a purple reaction. Results were consistent and reproducible and each species gave only one pattern of crystal violet reaction. Within the limited variety of species represented in the clinical isolates, Staphylococcus saprophyticus and S haemolyticus gave crystal violet purple reactions, in contrast to S epidermidis, which always gave a white reaction. Investigations suggested that the mechanism of the crystal violet test in S haemolyticus may be similar to that previously described in S aureus. Further work is needed to characterise the ability of crystal violet to modify S epidermidis and other central nervous system species. The crystal violet reaction, which has strong associations with invasiveness, phage group susceptibilities, colonisation persistence abilities, and nosocomial origin in S aureus may also be useful in studies of CNS disease.

Coagulase↗
PubMed1994

Evaluation of the rat embryo culture system as a predictive test for human teratogens.

Ingestion of the anticonvulsant drug valproic acid and of the angiotensin converting enzyme inhibitor captopril during pregnancy has been associated with abnormal fetal outcome in humans. In contrast, the use of the antiinflammatory drug ibuprofen and the antihistamine diphenhydramine has not been documented to be embryotoxic in humans. We evaluated the rat embryo culture system as a predictive model of teratogenesis, using these four drugs as test agents. Valproic acid, ibuprofen, and diphenhydramine were embryotoxic, inducing concentration-dependent decreases in growth and a significant increase in anomalies. Valproic acid caused an increase in neural tube defects, ibuprofen increased the incidence of abnormal maxillary processes, and diphenhydramine increased the number of embryos with distorted body morphology. These abnormalities were induced at concentrations of valproic acid and diphenhydramine that are used clinically, but ibuprofen only induced toxicity at concentrations greatly exceeding the therapeutic range. Captopril was not embryotoxic up to 5 mM, the highest concentration tested. These results suggest that the rat embryo culture system produces both false positive and false negative data on the teratogenic potential of drugs. Although such an in vitro assay may be suitable to determine the mechanism of teratogenesis, it is not a sensitive indicator of potential human teratogens on its own. These data support the view that in vitro systems can only supplement clinical and epidemiological observations in humans, possibly as a method to determine mechanisms of actions of teratogens.

Abnormalities, Drug-Induced↗
PubMed1994

Recreational exercise and cardiovascular status in the rural community of Tecumseh, Michigan.

BACKGROUND: Because of population stability, Tecumseh, a rural community in Michigan, was the site of health surveys over a period of three decades. METHODS: In the recent survey anthropometrics, blood pressure (BP), blood chemistry, echo/Doppler cardiac exam, personality and exercise questionnaires were collected on site. RESULTS: In this rural community 70% of subjects (447 men, 410 women, average age 30 years) do not engage in recreational exercise. Sedentary subjects were heavier (4 kg), had higher BP (2.3/2 mm Hg), faster heart rate (4 beats/min), and lower stroke volume (2 ml/m2) than physically more active subjects (p = 0.02 to 0.00001). Measures of cardiac structure and function were more favorable in exercising subjects. Cholesterol (+8 mg/dl), triglycerides (+15 mg/dl) and insulin (+2.4 microU/ml) were higher and HDL cholesterol was lower (-2 mg/dl) in the sedentary group (p = 0.04 to 0.003). Being sedentary was associated with more anxiety, anger and feeling time pressure (p = 0.001 to 0.00001). Exercise demands at work had no effect while even once a week recreational exercise was associated with a more favorable cardiovascular risk status. A difference in cardiovascular status between the sedentary and exercising subjects was not apparent throughout childhood, adolescence or early adult life, suggesting that subjects who exercise presently were not a priori healthier than presently sedentary subjects. CONCLUSIONS: Seventy percent of the residents studied in Tecumseh are physically inactive and have a less favorable cardiac risk profile. Enhancement of exercise habits may beneficially affect cardiovascular status and, presumably, the prognosis.

Adolescent↗
PubMed1994

Harvesting, characterization, and culture of CD34+ cells from human bone marrow, peripheral blood, and cord blood.

Stem and progenitor cells from a variety of sources including bone marrow, cord blood, and peripheral blood have been used for transplantation. This study compares CD34 cells from all three sources. Flow cytometry analysis of CD34 cells in multiple samples of normal peripheral blood and patient peripheral blood mobilized with chemotherapy (cyclophosphamide/VP16), chemotherapy plus granulocyte colony stimulating factor (G-CSF), and G-CSF alone were compared to bone marrow and cord blood. Although the relative distribution of CD34 percentages in each preparation of cells varied widely, on average the percentage of CD34 cells in these different preparations was 0.15%, 0.6%, 2%, 0.45%, 1.68%, and 0.83% respectively. CD34 subset analysis was performed on these cell preparations using multicolor flow cytometry and antibodies to CD33, CD13, CD45RA, CD19, CD71, and CD38. The major differences observed were that bone marrow CD34 cells contain high percentages of CD19+ cells not found in significant quantity in the other cell preparations and cord blood CD34 cells contained a higher percentage of CD38-cells than the other cell preparations. A magnetic bead system was used with anti-CD34 antibody to purify CD34 cells from mobilized peripheral blood apheresis products, cord blood, and bone marrow. Efficient selection with high purities of CD34 cells was achieved with each of the cell preparations. Comparison of colony-forming activity of each of the cell preparations showed cord blood and mobilized peripheral blood to have slightly higher cloning efficiencies than bone marrow with higher numbers of erythroid blast-forming units (BFU-E) also observed in cord blood CD34 cells. Culture of isolated CD34 cells in liquid culture with interleukin-3, stem cell factor, G-CSF, and granulocyte-macrophage GM-CSF showed over a 100-fold expansion in cell numbers after 25 days, with the peak expansion of colony-forming cells occurring between days 11 and 16. Analysis of day-10 cells from these cultures showed them to be predominantly promyelocytes, myelocytes, and metamyelocytes, with cord blood CD34 cultures showing more promyelocytes than peripheral blood or bone marrow and bone marrow showing more metamyelocytes. Comparison of the proliferation of CD34 cells from these different cell preparations showed that cord blood CD34 cells cultured for 10 days averaged an 85-fold increase in cell numbers followed by mobilized peripheral blood CD34 cells, with an average 56-fold increase, and bone marrow CD34 cells, with an average 49-fold increase.

Adult↗
PubMed1994

A microchip for quantitative detection of molecules utilizing luminescent and radioisotope reporter groups.

Through the marriage of microelectronics and molecular biology, a miniaturized device is presented for ultrasensitive detection of labeled molecules. The novelty of the approach is the direct integration of a charge-coupled device (CCD) and a probe-based assay. Specifically, a CCD detector serves as an active solid support that quantitatively detects and images the distribution of labeled target molecules near the spatially addressable pixels. The device exploits the inherent characteristics of microelectronics that accommodate highly parallel assays, ultrasensitive detection, high throughput, integrated data acquisition and computation. Hence, the technology presented offers substantial practical utility to both research and clinical diagnostic applications that require quantitative analysis of bound molecules. Specifically for probe-based assays such as reverse dot blots, hybridization of radiolabeled or fluorescently labeled, target DNA can be quantitatively assessed within seconds due to the high sensitivity and direct coupling employed.

DNA Probes↗