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Biomedical subjects

S Davidson

Publications and source records attributed to S Davidson.

At least 73 records · Page 4Linked to original sources
PubMed1996

Microbial lipases: production and applications.

Lipases occupy a prominent place among biocatalysts and have a wide spectrum of biotechnological applications. Lipases are unique as they hydrolyse fats into fatty acids and glycerol at the water-lipid interface and can reverse the reaction in non-aqueous media. The stability of these enzymes in organic solvents have pushed them into the frontier areas of organic synthesis leading to the designing of novel drugs, surfactants, bioactive compounds and oleochemicals. In addition, lipase-catalysed trans-esterification and inter-esterification reactions have been exploited in the fat industry. Looking into the wide scenario of lipase applications, commercialization of lipase production is a prime area of interest for microbiologists, process engineers and biochemists. Research carried out in this field has revealed that microbes, especially fungi and bacteria, are the tools of choice for commercial production. Recently, the structure determination of a few microbial lipases has widened our knowledge about the unique mechanism of catalysis of this enzyme.

Animals↗
PubMed1996

Necrotizing enterocolitis: the impact of the establishment of a Department of Pediatric Surgery on the Beilinson Medical Campus.

Necrotizing enterocolitis (NEC) is the most commonly acquired gastrointestinal emergency in neonates. We retrospectively surveyed all cases of confirmed NEC treated at the Beilinson Medical Center (BMC) (now Rabin Medical Center, Beilinson Campus) during a 12 year period to determine whether the establishment of a department of pediatric surgery has influenced the treatment and outcome of NEC patients. Of the 48 patients, 23 were patients treated in the "early period", 1982-87, when surgery was performed in the Department of General Surgery by staff trained in pediatric surgery (group I), and 25 were treated in the "later period" 1988-93, in the same neonatal intensive care unit, with surgical supervision by the new Department of Pediatric Surgery (group II). We found that 32% of the group II patients were of extremely low birthweight (<1,000 g) compared with 13% of group I. They also had lower Apgar scores, and a higher percentage needed respiratory assistance (56 vs. 26%, P = 0.02). All those infants of group II who had been born in other hospitals and were transferred to BMC for treatment were in an advanced state of disease and all required surgery. Total mortality decreased from 22% in group I to 8% in group II. This decrease may be attributed to improved supportive treatment in the neonatal intensive care unit, earlier surgery for NEC based on relative rather than absolute indications, higher rates of primary resection, and better postoperative care. Our review indicates that the establishment of a Department of Pediatric Surgery at the BMC has contributed to the considerable improvement in NEC outcome in our center.

Academic Medical Centers↗
PubMed1995

Are bilirubin and plasma lipid profiles of premature infants dependent on the lipid emulsion infused?

The effect of a lipid emulsion containing long-chain triglycerides (LCT) and supplemented with L-carnitine on plasma lipids and bilirubin in premature neonates on total parenteral nutrition was compared to that of lipid emulsions containing either LCT or a mixture of LCT and medium-chain triglycerides (MCT). In a double-blind randomized study 49 premature neonates received one of the three fat emulsions, given intravenously, over 16-20 h daily for 6 days. Plasma carnitine levels increased significantly in the supplemented group only; the addition of carnitine did not seem to affect any of the parameters studied. Mean plasma triglycerides rose by 193 and 199% in the carnitine-supplemented and the LCT groups, respectively, and by 314% in the MCT/LCT group. On the sixth day of the study free fatty acids were significantly higher in the MCT/LCT group than in the other two groups. Plasma phospholipids and free cholesterol increased (p < 0.05) progressively in all groups and were correlated (r = 0.74, p < 0.001). At the end of the 6-day study all groups showed a similar decline in free and total bilirubin levels despite the significant increase in plasma lipids and free fatty acids resulting from the stepwise increase in lipid load. No correlation was found between free fatty acids and free bilirubin. Since hyperbilirubinemia and hypertriglyceridemia appear to be clinically independent factors, the infusion of lipids should not be withheld from jaundiced infants on total parenteral nutrition.

Bilirubin↗
PubMed1995

In vivo growth of a murine lymphoma cell line alters regulation of expression of HSP72.

We have identified a murine B-cell lymphoma cell line, CH1, that has a much-diminished capacity to express increased levels of heat shock proteins in response to heat stress in vitro. In particular, these cells cannot synthesize the inducible 72-kDa heat shock protein (HSP72) which is normally expressed at high levels in stressed cells. We show here that CH1 fails to transcribe HSP72 mRNA after heat shock, even though the heat shock transcription factor, HSF, is activated correctly. After heat shock, HSF from CH1 is found in the nucleus and is phosphorylated, trimerized, and capable of binding the heat shock element. We propose that additional signals which CH1 cells are unable to transduce are normally required to activate hsp72 transcription in vitro. Surprisingly, we have found that when the CH1 cells are heated in situ in a mouse, they show normal expression of HSP72 mRNA and protein. Therefore, CH1 cells have a functional hsp72 gene which can be transcribed and translated when the cells are in an appropriate environment. A diffusible factor present in ascites fluid is capable of restoring normal HSP72 induction in CH1 cells. We conclude that as-yet-undefined factors are required for regulation of the hsp72 gene or, alternatively, that heat shock in vivo causes activation of hsp70 through a novel pathway which the defect in CH1 has exposed and which is distinct from that operating in vitro. This unique system offers an opportunity to study a physiologically relevant pathway of heat shock induction and to biochemically define effectors involved in the mammalian stress response.

Animals↗
PubMed1995

Development and maturation of the autonomic nervous system in premature and full-term infants using spectral analysis of heart rate fluctuations.

The changes in the power spectra of heart rate (HR) fluctuations, in particular the total power (within 0.02-2.0 Hz) and the power in the low- (0.02-0.2 Hz) and high- (0.2-2.0 Hz) frequency ranges, were computed from the ECG and respiratory signals of 59 premature and full-term infants. The objective of the study was to investigate the development and maturation of the autonomic nervous system from the first day of extrauterine life to several weeks of postnatal age. The study population was divided into four age groups. Group A: seven 1-d-old premature infants with gestational age of 34-35 wk. Group B: 28 premature infants 7-49 d old with a conceptional age of 34-35 wk. Group C: seven 1-d-old full-term infants of 39-41 wk gestation. Group D: six premature infants 35-97 d old with a conceptional age of 39-40 wk. Mean HR (+/- SEM) of groups C and D combined, i.e. 135 +/- 2 bpm, was significantly lower compared with groups A and B, i.e. 152 +/- 2 (p < 0.01). The mean (+/- SEM) of the low- to high-frequency power ratio obtained from the HR power spectrum decreased progressively from 71 +/- 31 in group A to 34 +/- 8 in group B, 16 +/- 3 in group C, and 17 +/- 2 in group D. The mean low to high ratio for the combined groups C and D, 17 +/- 1, was significantly lower compared with the combined group A and B, i.e. 44 +/- 9 (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Autonomic Nervous System↗
PubMed1995

Surgical management of patients with endometrial cancer and cervical involvement.

OBJECTIVE: To evaluate the role of extrafascial hysterectomy in the management of women with endometrial carcinoma and cervical involvement. METHODS: A review of 238 medical records of patients with endometrial cancer treated at the Weiler Hospital of the Albert Einstein College of Medicine and Montefiore Medical Center from 3/86 to 3/91 was performed. Thirty-one patients were selected based on histopathologic documentation of cervical involvement in the surgical specimen. Fisher exact probability test, Kaplan-Meier and Log-Rank procedures were used for the statistical analysis of the data. RESULTS: Two patients were excluded as they received preoperative radiotherapy. Nineteen patients had Stage II disease and ten were found to have Stage III (two for positive washings, eight for positive pelvic and/or para-aortic nodes). Sixteen of 19 patients with Stage II disease received postoperative pelvic radiotherapy. Six patients with Stage III received postoperative radiotherapy, four with Stage III received chemotherapy. The probability of survival for Stage II patients was 72%, for Stage III 33% and the entire group was 60% (median follow-up 55 months). CONCLUSIONS: Extrafascial hysterectomy was performed without major complications in 86% of patients with endometrial carcinoma and microscopic cervical involvement. This procedure may be considered an adequate first line of treatment for patients without gross cervical spread of the disease.

Aged↗
PubMed1994

Determination of measles, mumps, and rubella immunization status using oral fluid samples.

OBJECTIVE: To determine if oral fluid samples can be used to reliably assess protective blood levels of antibodies to measles, mumps, and rubella. DESIGN: A comparison of matched serum and oral fluid samples from asymptomatic subjects in enzyme-linked immunosorbent assays for measles, mumps, and rubella antibodies. A longitudinal study compared matched serum and oral fluid samples from 11 subjects after measles-mumps-rubella vaccination. SETTING: Five US clinical sites with samples tested at the reporting laboratory. PARTICIPANTS: A total of 157 asymptomatic subjects including 55 subjects younger than 18 years. MAIN OUTCOME MEASURES AND RESULTS: The presence of antibodies in oral fluid specimens correlated with that in serum with the following levels of sensitivity and specificity: measles, 97% and 100%, respectively; mumps, 94% and 94%, respectively; rubella, 98% and 98%, respectively. Longitudinal studies of subjects after vaccination showed similar seroconversion profiles in oral fluid and serum samples. CONCLUSION: Protective blood levels of antibodies to measles, mumps, and rubella can be assessed by means of an oral fluid sample with good reliability.

Adolescent↗
PubMed1994

Psychosocial factors associated with risky sexual behavior among HIV-seropositive gay men.

The present study examines sociodemographic characteristics, levels of psychological distress, and coping styles among HIV-seropositive (HIV+) gay men who either did or did not engage in sexual activity which placed others at risk for HIV infection. Risky sexual behavior was defined as engaging in insertive anal intercourse. Respondents were 156 HIV+ men enrolled at the Pittsburgh site of the Multicenter AIDS Cohort Study in 1989-90. HIV+ men who engaged in risky sexual behavior, while similar to remaining HIV+ men on most sociodemographic characteristics, showed lower levels of psychological distress and somewhat higher feelings of control over their lives. Risky men were less likely to employ active, behavioral strategies for day-to-day coping with the issues of HIV infection and AIDS, and were more likely to report using recreational drugs to reduce tension associated with thoughts about HIV. This profile of psychosocial characteristics associated with risky sexual activity may lead to further refinement of educational and other intervention strategies with HIV+ men. Implications for such strategies are discussed.

Adult↗
PubMed1993

Lactic acid as a predictor for erythrocyte transfusion in healthy preterm infants with anemia of prematurity.

Elevated blood lactate levels that declined to normal after erythrocyte transfusion were observed in 17 of 37 otherwise healthy infants with anemia of prematurity (26.1 +/- 2.1 mg/dl vs 12.3 +/- 0.9 mg/dl; p < 0.001). Posttransfusion heart rate in this group decreased from 155 +/- 1 beats/min to 150 +/- 2 beats/min (p = 0.01). Blood lactate concentration may be a predictor of the need for transfusion in anemia of prematurity.

Anemia, Neonatal↗
PubMed1992

Autosomal dominant congenital laryngomalacia.

A family is presented in which congenital stridor due to laryngomalacia was evident in 9 individuals through 3 generations. This report confirms the autosomal dominant transmission of at least one type of laryngomalacia.

Adult↗