Search PubMed⌕ Search

Biomedical subjects

S Davidson

Publications and source records attributed to S Davidson.

At least 91 records · Page 5Linked to original sources
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↗
PubMed1992

Systemic candidiasis in babies with retinopathy of prematurity.

Fifteen premature babies developed systemic candidiasis during the administration of intravenous hyperalimentation in the Beilinson Neonatal Intensive Care Unit. Candida albicans was found in the blood cultures of all the babies and in the urine cultures of 66.7% of them. Repeated funduscopic examinations revealed no evidence of septic embolization in the retinal or choroidal circulation. It should be noted that acute retinopathy of prematurity (ROP) grade 2 or 3 was found in all the babies.

Candida albicans↗
PubMed1992

Cytotoxicity of 5-aza-2'-deoxycytidine in a mammalian cell system.

After the addition of 5-aza-2'-deoxycytidine, a potent inhibitor of DNA methylation and S-phase-specific cytotoxic agent, metaphase chromosomes of Chinese hamster ovary (CHO) cells exhibited a highly decondensed and extended morphology (numerous "fragile sites") at the first mitotic division. However, when a lethal dose of this drug was added in early G1 phase to cells synchronised by mitotic selection, the majority subsequently divided at the same time as an untreated control cell population with few division abnormalities and with few of the more usual types of chromosome aberrations such as gaps, breaks and exchanges. The drug-treated cells also entered and completed the second S-phase without significant delay and it was only at the second mitosis after addition of 5-azadeoxycytidine that cells showed delays in entering mitosis and significant increases in abnormal divisions concomitant with a modest increase in chromosome aberrations. If cells in a tumour behave similarly, the tumour mass would be expected to double before any reduction in tumour burden could be expected to occur.

Animals↗
PubMed1992

Gastrin induction of histamine release from primary cultures of canine oxyntic mucosal cells.

Using enzyme-dispersed canine oxyntic mucosal cells, we studied regulation of histamine release from fractions in which mast cells were largely removed by density gradient. Histamine-like immunoreactivity was demonstrated using peroxidase-anti-peroxidase immunohistochemistry. Histamine-containing cells in the small cell elutriator fractions (SCEF) were further separated by albumin step density gradients. Approximately 2.5% of cells in the low density fraction (LDF) contained histamine-like immunoreactivity; this fraction was largely depleted of the more dense mast cells (0.5%). These two fractions were cultured for 48-64 h on a Matrigel substrate. The cell content of histamine and release into the medium were measured by radioenzymatic assay. Gastrin, carbachol, and forskolin increased histamine release from the LDF. The induction of histamine release by gastrin was evident within 5 min and was sustained for at least 60 min. The response to gastrin was dose dependent between concentrations of 10(-11) and 10(-8) M. In contrast, in the mast cell-enriched SCEF, basal release was higher and gastrin was without effect; however, concanavalin A stimulated and epinephrine inhibited histamine release indicating that histamine-release mechanisms were intact in this fraction. Our methods provide a preparation of low density oxyntic mucosal histamine cells that demonstrate gastrin-responsive histamine release; we speculate that enterochromaffin-like cells account for this gastrin response.

Animals↗
PubMed1992

Misdirected attachment behaviour--an unusual outcome of repeated hospitalization?

This paper describes an infant with multiple congenital anomalies who developed an unusual reaction to recurrent hospitalization before age two. After spending much of her first year in hospital, she protested strongly whenever she left the hospital. We report the evolution and treatment of this patient's misdirected attachment behaviour.

Adult↗
PubMed1991

Diabetic BB/Wor rat haptoglobin exhibits a probable structural abnormality in Asn-linked oligosaccharides.

In this study we demonstrate that haptoglobin, a serum glycoprotein secreted by the liver, has altered structure in the BB/Wor diabetic rat. SDS-PAGE of haptoglobin (a tetramer composed of two glycosylated beta-chains each containing two sites for Asn-linked oligosaccharides connected by disulfide bonds with two nonglycosylated alpha-chains) clearly shows that the beta-chain of haptoglobin from diabetic rats is smaller than normal, with a molecular mass of 39 instead of 40 kDa. Both acute and chronic diabetic rats exhibit the defect. Defective haptoglobin appears in the serum within 4 days of onset of the disease, but insulin therapy prevents the defect. Removal of Asn-linked oligosaccharides with peptide: N-glycosidase F from Flavobacterium meningosepticum abolished the size difference between the beta-chains from normal and diabetic haptoglobin, with the molecular mass in both cases shifting to 30 kDa. Haptoglobin from both normal and diabetic rats was resistant to digestion by endoglycosidase H from Streptomyces griseus, which cleaves high mannose-type chains. Removal of sialic acid with neuraminidase treatment resulted in a reduction in the molecular mass in both cases, but without eliminating the size difference between the two. These results demonstrate that haptoglobin from diabetic BB/Wor rats contains a structural abnormality which correlates with onset of the disease. The defect is most likely due to an alteration in Asn-linked oligosaccharides, probably involving a change in the neutral sugars of complex-type oligosaccharide chains. This finding represents the first example of an altered Asn-linked oligosaccharides in diabetes.

Animals↗
PubMed1991

Genital mycoplasmas in preterm infants: prevalence and clinical significance.

The genital mycoplasmas: Ureaplasma urealyticum and Mycoplasma hominis have recently assumed an increasing importance as neonatal pathogens. The aim of the present survey was to determine the prevalence of infections with these organisms in preterm infants in two neonatal intensive care units in Israel. Among 99 preterm infants, 24 (24%) harboured mycoplasmas in their throats shortly after birth. U. urealyticum was the most common organism. M. hominis was isolated only from 3 infants. Six out of 27 (22%) mechanically ventilated infants secreted U. urealyticum in their lower airways. The rate of colonization was inversely correlated with gestational age; 80% of infants younger than 28 weeks gestation were found to be colonized as opposed to 17.9% at 28-36 weeks of gestation. No mycoplasmas were isolated in blood cultures drawn from 146 infants and CSF cultures obtained from 47 preterm infants. Neonatal mortality, respiratory complications and intraventricular haemorrhage grade 3-4 were significantly increased in colonized infants. However, above gestational age of 27 weeks, colonization with mycoplasmas was not associated with a worse prognosis. We conclude that colonization with U. urealyticum is common in Israeli preterm infants, correlates inversely with gestational age and has no detrimental effect on neonatal morbidity and mortality of infants older than 27 wks of gestation.

Genitalia↗
PubMed1991

Premedication before elective breast surgery, a comparison between ketobemidone and midazolam.

One hundred female patients scheduled for elective breast surgery (mean age 60 +/- 11 years were randomly assigned to receive one of two premedications: ketobemidone (Ketogan) 1-1.5 ml or midazolam 4-5 mg, intramuscularly. The effects on preoperative anxiety and postoperative emetic sequelae were studied. All patients were anaesthetised with thiopentone, fentanyl and atracurium, and ventilated with a mixture of nitrous oxide in oxygen with supplementary isoflurane. Sixty-nine percent of the midazolam- and 50% of the ketobemidone-premedicated patients experienced a reduction in anxiety. Midazolam was found to be more effective than ketobemidone in reducing anxiety among more tense patients--those with a VAS grading before premedication of 2 or more (P less than 0.05). Midazolam-premedicated patients were also assessed by observers as being more relaxed (P less than 0.05). No difference was seen in the frequency of emetic sequelae: 20 patients in the midazolam group and 14 patients in the ketobemidone group vomited once or more during the 24-h observation period. There was no difference between the two groups in time until an analgetic was required. In conclusion, midazolam seemed more effective in reducing preoperative anxiety than ketobemidone without any negative effects on postoperative emesis or time until an analgetic was required.

Aged↗
PubMed1991

Opioid supplementation to propofol anaesthesia for outpatient abortion: a comparison between alfentanil, fentanyl and placebo.

One hundred and sixty-four patients scheduled for elective termination of pregnancy under general anaesthesia were randomly assigned to receive one of three different supplements to propofol and oxygen in nitrous oxide anaesthesia: 0.1 mg fentanyl, 0.5 mg alfentanil or placebo. Postoperative pain and nausea, as well as complications during anaesthesia were studied. There were no differences in complications or complaints by surgeons during anaesthesia, and no patient in any group reacted unsatisfactorily to surgery. The patients in the placebo group consumed significantly more propofol during the procedure (P less than 0.001). No differences were seen in time until hospital discharge between the three groups. Complaints about postoperative pain were significantly less frequent among patients receiving fentanyl (P less than 0.01). The number of patients requesting postoperative analgetics, however, did not differ. There was no difference in the frequency of nausea or vomiting, but postoperative pain was found significantly to increase complaints of nausea (P less than 0.01) and also time until hospital discharge (P less than 0.01). In conclusion, opioid supplementation lowered the amount of propofol needed for anaesthesia. Alfentanil 0.5 mg did not improve the postoperative course. Fentanyl 0.1 mg decreased the frequency of postoperative pain without increasing the time to hospital discharge.

Abortion, Induced↗
PubMed1991

Normal ranges of hip motion of preterm infants.

The hip motion of 158 preterm infants with gestational ages between 25 and 36 weeks was measured. The results of this study, compared with those of previous studies of term infants, show that hip motion changes with increasing gestational age above 25 to 27 weeks.

Female↗