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Biomedical subjects

S Levy

Publications and source records attributed to S Levy.

At least 361 records · Page 20Linked to original sources
PubMedDate not supplied

Ion selective microelectrodes: computer-controlled calibration, plotting, and data analysis.

Calibration of ion-selective microelectrodes involves delivering and measuring the potential of several different solutions both before and after intracellular measurement. A microprocessor-controlled system is described which completely automates that tedious process. The microcomputer controls the delivery of the calibration solutions and prints out the calibration value along with the solution number. A second program plots the calibration curve using a modified Nicholsky equation and a third program converts intracellular ion signals into ion concentration. Specific examples based on Ca-selective microelectrodes are shown.

Autoanalysis↗
PubMedDate not supplied

Oxygen uptake occurs faster than sodium pumping in bee retina after a light flash.

When neurones are active there is an entry of Na+, which must subsequently be pumped out, and an increase in their oxygen consumption rate (Qo2). The Na+ pump derives its energy from ATP, splitting it into ADP and Pi, and it has reasonably been proposed that the changes in concentrations of ATP, ADP and Pi lead to a stimulation of the O2 consumption by the mitochondria and hence to a restoration of the stock of ATP. Here we present evidence suggesting that Qo2 must be controlled differently in the retinal photoreceptor cells of the honeybee drone. Stimulation of drone photoreceptors with a flash of light causes an entry of Na+ (ref. 4) and a transient increase in Qo2 that indicates respiration of the right order of magnitude to provide ATP to pump the Na+ out. We report intracellular recordings of changes in intracellular sodium (Nai+) and potassium (Ki+) in response to single light flashes and have compared the time course of extra oxygen consumption (delta Qo2) with these ion changes and other indices of Na+ pumping. We found that the time course of pumping seems to lag behind the time course of delta Qo2. It follows that the mitochondrial respiration must be stimulated by some signal which is generated earlier than the rise in ADP produced by the Na+ pump.

Adenosine Triphosphate↗
PubMedDate not supplied

Nursing directors' perceptions of the dental components of the Minimum Data Set (MDS) in nursing homes.

The Directors of Nursing (DON's) of all 428 nursing homes in the state of Iowa were sent a pre-tested questionnaire. The aim of the study was to examine the perceptions by nursing directors on the utility of a dental component of the Minimum Data Set (MDS) in identifying residents with dental problems in their facility. The return rate was 55.1% from the DON's. It was reported that 66.4% of the homes had a training program for the MDS and that in 38.0% of the homes there was only one person doing the assessments. The majority (76.0%) of the DON's stated that the MDS was useful in tracking residents and that it did help them to identify dental problems. When asked how often it was useful in the identification of dental needs, only 9% stated that it was often useful. Also, regarding frequency of dental appointments for the residents, a mean of 51.0% of residents were estimated to have received some dental care during the previous year (means of 33.2% at the facility, 22.4% at a dental office, and 0.4% in a hospital). If change is to occur, the dental profession must try to get the nursing home assessors to convince the nursing homes to use the oral/nutritional/dental sections of the MDS as they were intended under the OBRA regulations.

Appointments and Schedules↗
PubMedDate not supplied

Maintenance of GI function after bowel surgery and immediate enteral full nutrition. I. Doubling of canine colorectal anastomotic bursting pressure and intestinal wound mature collagen content.

Following either standardized stapled resection of an ileal blind loop terminus (17 beagles) or construction of a colorectal anastomosis (10 beagles), half the subjects immediately were fed an elemental diet (Vivonex HN). Gastrointestinal (GI) motility and absorption were maintained by exclusion of swallowed air. Controls received the same rate of feeding solution containing only the electrolyte components. Four days postoperatively, the fed beagle's colorectal anastomosis had over double the bursting pressure of the control, 303 +/- 46 mm Hg (p less than 0.001). At this time, the mature collagen content of the fed subjects' ileal wound was undiminished from that of normal ileum 2,223 +/- 336 versus 2,250 +/- 577, contrasting with the 45% decrease of this structural component (OHP) in the wounds of the unfed controls, 1,237 +/- 820 microgram/g of tissue (p less than 0.001). Similarly, the wounds of fed but not unfed subjects had a doubling (p less than 0.001) in concentration of collagen precursors and "new" collagen. The "catabolic" and "lag" phases, as noted in unfed experimental animals, appeared to be reflections of the relative starvation that accompanied the intestinal wounding. With maintenance of GI function and immediate full enteral nutrition, "accelerated healing" was noted relative to the previously considered "norm".

Animals↗
PubMedDate not supplied

Efficacy of celecoxib in treating symptoms of viral pharyngitis: a double-blind, randomized study of celecoxib versus diclofenac.

This study compared the efficacy and safety of the cyclooxygenase-2 specific inhibitor celecoxib with the conventional non-steroidal anti-inflammatory drug diclofenac in the symptomatic treatment of viral pharyngitis. Adult patients from 27 study centers in Latin America were treated with oral doses of celecoxib 200 mg once daily or 200 mg twice daily, or diclofenac 75 mg twice daily for 5 days in a double-blind, randomized study. The primary efficacy assessment was 'Throat Pain on Swallowing' on day 3. In addition, secondary quality-of-life assessments were performed on days 3 and 5. All adverse events and treatment-emergent signs and symptoms were recorded. Data from 313 patients were evaluable for efficacy (105 celecoxib 200 mg once daily, 107 celecoxib 200 mg twice daily, 101 diclofenac 75 mg twice daily). The upper 95% confidence limits for the visual analog scale of 'Throat Pain on Swallowing' on day 3 for celecoxib 200 mg once daily relative to diclofenac 75 mg twice daily, and celecoxib 200 mg twice daily relative to diclofenac 75 mg twice daily were 9.26 and 7.83, respectively. All secondary efficacy and quality-of-life measures were clinically similar for the three treatment groups, and no statistically significant differences were detected. The incidences of treatment-emergent adverse events and withdrawals due to adverse events were similar for all groups, but numerically higher among patients taking diclofenac than celecoxib. More patients in the diclofenac group reported gastrointestinal complaints (7.3%) compared with those in the celecoxib groups (4.3% in the celecoxib 200 mg once-daily group and 3.4% in the celecoxib 200 mg twice-daily group). In conclusion, 5 days of treatment with celecoxib 200 mg once daily is as effective as diclofenac 75 mg twice daily in the symptomatic treatment of viral pharyngitis. Celecoxib 200 mg once daily is also as effective as celecoxib 200 mg twice daily in this condition.

Adolescent↗
PubMedDate not supplied

The effects of aging on the seminiferous epithelium and the blood-testis barrier of the Brown Norway rat.

Steroidogenesis and spermatogenesis decrease in aging Brown Norway rats. We therefore hypothesized that there must be accompanying morphological changes taking place in the seminiferous tubules of the aging testis. The testes of Brown Norway rats ranging in age from 3 to 24 months were prepared for light and electron microscopy. To assess the integrity of the blood-testis barrier with age, a lanthanum nitrate study was done. The normal seminiferous tubules present in rats at 3 and 12 months of age were largely replaced at 24 months by fully regressed tubules that were virtually devoid of germ cells and contained large intercellular spaces. An electron-microscopic study of these regressed tubules showed a complete loss of cyclical variations of the organelles of the Sertoli cells. The nucleus was more irregularly shaped and was present at various levels in the epithelium. The endoplasmic reticulum was a loose, vesiculated network that was unlike the elaborate, tubular, anastomotic network noted in young animals. The lysosomes were large, oddly-shaped, and contained lipidic inclusions, in contrast to the distinct membrane-bound lysosomes and dense core bodies found in the young animals. Adjacent Sertoli cell processes encompassed large, empty intercellular spaces, possibly occupied previously by germ cells. The typical Sertoli-Sertoli junctions of the blood-testis barrier in the young animal were rarely seen at 24 months and were replaced by focal contact points, usually between three Sertoli cell processes. In the aged animals, lanthanum nitrate permeated the basal and adluminal compartments, extending between Sertoli cell processes and entering the intercellular spaces and lumen. In summary, during aging, there is a breakdown of the blood-testis barrier, and there are striking changes in the appearance of Sertoli cells. These results suggest a possible intrinsic limitation that prevents stem cells from renewing themselves, whether because of a degeneration of immunological origin or because of a lack of Sertoli cell support.

Aging↗
PubMedDate not supplied

Localization of T and B lymphocytes in human adenoid, tonsil, appendix and Peyer's patches.

T and B lymphocytes were detected in human adenoid, tonsil, appendix and Peyer's patches by adherence to sheep erythrocytes (E) and human erythrocytes sensitized with antibody and complement (HEAC). The percentages of T lymphocytes in adenoid and tonsil cell suspensions averaged 30.9 +/- 3.4 (S.D.) and 35.8 +/- 6.4 (S.D.). The percentages of B lymphocytes in the same tissues were 42.5 +/- 11.3 (S.D.) and 40.1 +/- 34 (S.D.) respectively. In adenoid and tonsil tissue sections, B lymphocytes were found in the follicles and T lymphocytes were detected around the follicular areas. The predominant cell population in Peyer's patches and appendix sections was constituted by B lymphocytes.

Adenoids↗
PubMedDate not supplied

Health effects from exposure to organophosphate pesticides in workers and residents in Israel.

Major findings from our work on exposures and effects from organophosphate-containing pesticides in selected occupational and community patients and groups in Israel are reviewed as a basis for recommending control measures. The worker groups were pilots, ground-crews, and field workers; exposed nonworkers were adults and children living in kibbutzim with drift exposures, and household residents in houses treated by pest exterminators. In all groups, evidence of exposure-illness associations was found even though persons with acute poisoning were not seen. Complaints (headache, dizziness, fatigue, nausea, breathing problems, abdominal cramps, and tingling in extremities) were associated with within-normal depressions in cholinesterase activity. Whole blood and plasma cholinesterase activity were slightly more sensitive indicators of mixed exposure than red blood cell cholinesterase activity. High alkyl phosphate levels and symptoms were seen in individuals with within-normal limit depressions in cholinesterase activity. Complaints of weakness and tingling in hands and feet, together with low-grade changes in nerve conduction, suggest the possible influence of agents with a neurotoxic esterase-type activity independent of cholinesterase activity. Transient in-season neuropsychological changes in tests of mood status and performance were associated with exposure. Recommendations for exposure reduction include: accelerating the already declining use of pesticides in general, and organophosphates in particular; promoting the shift from more to less toxic organophosphates and other pesticides; and introducing rigid performance specifications for closed systems in loading and mixing at end-user sites. Dermal protection remains a problem. Cholinesterase activity levels and symptom interviews are useful for monitoring workers at risk, but alkyl phosphate levels are the definitive measure of exposure, surveys, investigations and surveillance.

Adolescent↗
PubMedDate not supplied

Tobacco-related attitudes and counseling practices of Iowa dentists.

Evidence suggests that dentists' efforts to encourage their patients to stop tobacco use can significantly decrease tobacco-related morbidity and mortality. This study identified attitudes and counseling practices of 1116 Iowa dentists and compared results of a subgroup (N = 55) surveyed in both 1983 and 1989 to note changes in their tobacco-related attitudes and practices. Although only 9% of the dentists from the statewide survey felt counseling their patients on tobacco use was inappropriate, 56% reported they did not routinely ask their new patients about tobacco use. With some frequency 90% of the dentists discussed negative health effects of tobacco, whereas only 64% advised their smokers to quit. In addition, fewer than half made special efforts with pregnant patients or those at high risk for heart disease. The vast majority reported seldom if ever using intervention tools such as pamphlets or referral to cessation programs. Data from the subgroup surveyed in 1983 and 1989 indicated few substantial changes in attitudes and counseling practices. Substantial discrepancies exist between dentists' attitudes and counseling practices. Well-designed programs are needed to help dentists select and implement appropriate interventions.

Attitude to Health↗