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Biomedical subjects

S Davidson

Publications and source records attributed to S Davidson.

At least 109 records · Page 6Linked to original sources
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↗
PubMed1990

Synthesis of chondroitin sulfate D and heparin proteoglycans in murine lymph node-derived mast cells. The dependence on fibroblasts.

Proteoglycans synthesized in cultured mast cells derived from horse serum-immunized lymph node cells were analyzed. Treatment of the 35S-proteoglycans extracted from these cells with either chondroitinase ABC or AC resulted in 95% +/- 7% and 84% +/- 7%, respectively (mean +/- S.E., n = 3), of the radioactivity associated with disaccharides eluting in the included volume of PD-10. The 35S-proteoglycans were not hydrolyzed by nitrous acid elimination treatment. The chondroitinase ABC-generated disaccharides were analyzed by aminocyano high performance liquid chromatography. 35S-Disaccharides eluted in a major peak at a retention time of 8.1 min, corresponding to the disaccharide of chondroitin 4-sulfate proteoglycan (delta Di-4S), and a second peak at 12 min, corresponding to the disaccharide of chondroitin sulfate D proteoglycan (delta Di-diSD). Further treatment with chondro-4-sulfatase did not affect the retention time of the disaccharide corresponding to delta Di-diSD whereas this peak disappeared after the digested proteoglycan was treated either by chondro-6-sulfatase or by both sulfatases. Therefore, this disaccharide was identified as chondroitin sulfate D. Quantification of the radiolabeled disaccharides showed that delta Di-diSD contributed 20% +/- 2% (n = 3) of the total sulfated disaccharides of the chondroitin sulfate of these cultured cells. The role of fibroblasts in inducing the shift of chondroitin sulfate D into heparin proteoglycan in these mast cells was also investigated by using three types of monolayers: mouse embryonic skin fibroblasts (MESF), rat embryonic skin fibroblasts (RESF), and 3T3 fibroblasts. 35S-Proteoglycans that were extracted from the lymph node-derived mast cells cultured for 30 days on MESF and on 3T3 fibroblast monolayers were 93% +/- 4% and 30% +/- 7% (n = 3) susceptible to nitrous acid elimination, respectively. No degradation by nitrous acid was observed in 35S-proteoglycans extracted from cells cultured on RESF monolayer. Since the MESF was found to be the most potent monolayer in the induction of heparin synthesis, the kinetics of changes in the synthesis of proteoglycan types were determined in lymph node-derived mast cells cultured on MESF for up to 30 days. It was found that the synthesis of chondroitin sulfate gradually declined whereas that of heparin starting between 4 and 7 days after plating gradually increased. From the 17th day on, only the synthesis of heparin was detected.

Animals↗
PubMed1990

Energy intake, growth, and development in ventilated very-low-birth-weight infants with and without bronchopulmonary dysplasia.

Seventy-one ventilated very-low-birth-weight infants (birth weight, 500 to 1250 g) with (n = 30) and without (n = 41) bronchopulmonary dysplasia were studied to compare their growth achievements and to determine the association between neurodevelopmental outcome, growth, and nutrition. Growth delay was observed in both groups. No association was found between head circumference and percent weight loss, age to full gavage feeds, age to regain birth weight and energy intake at 2 and 4 weeks of life. Fifty percent of infants with bronchopulmonary dysplasia and 37% of the control group had minor and major handicap. Mean duration of assisted ventilation was significantly longer in handicapped infants (21.5 vs 12.5 days; F = 6.49; df = 1,53). No association was found between abnormal neurodevelopmental outcome and weight, length, and head circumference at 12 and 21 months after term. Although mean energy intake per kilogram per day at 2 weeks of life was significantly lower in handicapped infants (344.82 vs 412.86 kJ; F = 7.6; df = 1,53), age to regain birth weight, age to full feeds, percent weight loss, and energy intake at 4, 6, and 8 weeks of life did not differ significantly between normal and handicapped infants. Aggressive nutritional support to promote growth in ventilated very-low-birth-weight infants may not influence the neurodevelopmental outcome.

Anthropometry↗
PubMed1990

Secretion of mucoid material by lymphokine-activated killer cells: study by light and electron microscopy.

When lymph node cells from nude mice were grown on embryonic fibroblast monolayers together with rat interleukin-2, only one type of colonies developed. These colonies were composed of cytotoxic cells termed "granular/lymphokine-activated killer/mucus-secreting cells" (LAK-GM). An extensive differentiation course, in which all the cellular components were involved, ended with a population of short-lived, mature, nondividing large cells that apparently synthesized and deposited a flowing mucoid material (FMM) that stained distinctly blue with periodic acid-Schiff/alcian blue (PAS-Ab) at pH 1 and distinctly red by the naphthol AS-D-chloracetate method for specific esterase. So far, the best monolayers to trigger the FMM synthesis were those prepared from 16- to 18-day-old whole embryos. These cells were compared with LAK cells that developed on monolayers (such as embryonic skin or adult kidney) that did not trigger FMM synthesis. They were also compared with other cell types that differentiated in colonies on the fibroblast monolayers: histiocytes (fixed macrophages), mixed granulocytes/monocytes, mucosal mast cells; and with populations of mature rat T-killer cells developed on same mouse monolayers. Features distinctive to the secreting LAK-GM cells were presence of masses of membrane-limited vesicles that were strictly confined to the surface of the cells in FMM-containing colonies. All transitional forms of budding activity could be seen on the cell surface facing the masses. Within the same cells, many granules displayed varying degrees of degradation, the granular material being transformed into flocculent material that formed small pools facing each degraded surface. Other characteristics of the LAK-GM lineage were the accumulation of glycogen prior to the appearance of the FMM, the presence of several structures of a ribosome-lamella complex in the LAK-GM in colonies that did not accumulate FMM, and filopodia commonly emerging from the pole proximal to the nucleus. Of various fixation methods tried, only after treatment with absolute alcohol and subsequent drying was the FMM stained with PAS-Ab. By subsequent wetting, the capacity to be stained was irreversibly lost. After incubation of the living cultures with the enzymes hyaluronidase or chondroitinases AC or ABC, the FMM disappeared. These observations suggest a triggering mechanism by the embryonic mesenchymal fibroblastoid cells for synthesis and secretion of mucous material that is a proteoglycan of the chondroitin sulfate group.

Animals↗
PubMed1990

Pulmonary interstitial emphysema in low birth weight infants: characteristics of survivors.

Twenty out of 303 ventilated low birth weight infants, hospitalized in the Beilinson Medical Center's Intensive Care Unit, during the years 1984-1986, developed pulmonary interstitial emphysema. Eighteen infants had very low birth weight (less than 1500 grams) and 17 were less than 30 weeks' gestation. The mean birth weight was 987 +/- 311 and mean gestational age 27.7 +/- 2.5. Eight infants survived the pulmonary disease. There were no significant differences in the neonatal parameters between infants who died or survived. However, the survivors had a significantly lower maximal peak inspiratory pressure and FiO2 on the first day of ventilation. The incidence of pneumothorax and asphyxia was the same in both groups.

Humans↗
PubMed1990

Influence of presentation on neonatal outcome of vaginally delivered low birthweight infants. A matched pair analysis.

Neonatal outcome of 30 low birthweight (800 to 2000 g) breech infants delivered vaginally was compared with a matched sample of vaginally delivered vertex infants. Using a multiple regression analysis, presentation was found to be significantly related only to the Apgar score at 1 minute. No effect of presentation was found on Apgar score at 5 minutes, length of stay in the nursery, need for ventilatory support, or incidence of neonatal death, seizures, or intracranial hemorrhage. Thus, vaginal delivery of low birthweight breech fetuses was associated with short-term infant outcomes comparable to those of similar fetuses delivered vaginally from vertex presentations. The findings suggest that prevailing assumptions about the risks of premature breech vaginal delivery need to be evaluated critically.

Apgar Score↗
PubMed1989

Intravenous/oral ciprofloxacin therapy of infections caused by multiresistant bacteria.

Sixty patients were treated with ciprofloxacin: 19 received only intravenous ciprofloxacin, 41 received intravenous followed by oral ciprofloxacin. The mean duration of therapy was 28 days in the intravenous only group and 10 days intravenously and 80 days orally in the intravenous/oral group. Ten (17 percent) patients received 200 mg intravenously every 12 hours and 49 (82 percent) 300 mg every 12 hours. The overall clinical response was 85 percent, with a bacteriologic response of 70 percent. The lowest bacteriologic response (38 percent) occurred in the 13 patients treated for Pseudomonas respiratory infection. Clinical response occurred in 24 of 26 patients with soft-tissue infection, and 10 of 13 patients with respiratory infection. Of three patients with endocarditis, therapy failed in two with resistance developing in Pseudomonas aeruginosa and Staphylococcus aureus. Overall, 19 percent of 26 P. aeruginosa isolates developed resistance to ciprofloxacin. Toxicity was minor, with phlebitis and nausea most commonly reported. Intravenously administered ciprofloxacin or intravenous followed by oral ciprofloxacin is a safe, effective therapy for serious infections due to multiply resistant gram-negative bacteria, including P. aeruginosa and S. aureus.

Administration, Oral↗
PubMed1989

Tuberculosis of the middle ear in an infant.

Tuberculosis of the middle ear is currently a rare disease. As most physicians are unfamiliar with the typical presenting features, the diagnosis is made too late, with resulting complications, such as irreversible hearing loss and facial nerve paralysis. A case report and review of the literature are presented, emphasizing that tuberculosis should be considered in the differential diagnosis of chronic ear infection.

Diagnosis, Differential↗
PubMed1989

Structural alterations in fibroblast monolayers caused by mast cell degranulation.

Populations of mature, long-lived, nondividing mast cells develop on embryonic fibroblast monolayers after 1 mo growth of lymph node cells taken from mice immunized with horse serum. Total mast cell degranulation with 80-90% histamine release has been obtained by monoclonal anti-2,4-dinitrophenol (anti-DNP) IgE and the antigen. This degranulation process was studied by time-lapse cinematography and scanning electron microscopy. Excitation of the mast cells began as early as 10 s after addition of the antigen and lasted for about 15 s. Consequently, the fibroblast cytoplasm was displaced by short 5-10 s movements. Before degranulation, due to an extracellular film that coated the cells and the extracellular fibers, the monolayer appeared as a continuous, uninterrupted layer. After degranulation and fibroblast cytoplasm displacement, the fibrous network was exposed. Several inhibitors and antagonists of mast cell mediators were introduced to the cultures prior to addition of the antigen. So far, only with soybean trypsin inhibitor was the cytoplasm dislocation inhibited. Histamine H1 and H2 and serotonin receptor antagonists, as well as indomethacin, cortisol, aprotinin, and phenylmethylsulfonyl fluoride, did not inhibit. These results suggest that chymase, which constitutes the greater part of the mast cell granule protein, is the causative agent.

Animals↗
PubMed1989

Computerised evaluation of the electrocardiogram during and for a short period after gall bladder surgery.

Long-term ECG recording on tape (LTER) was performed in 32 consecutive patients undergoing cholecystectomy. Twenty-two of the patients recorded showed ST-segment changes during the per- and early post-operative period. ST-segment depression was the most common change seen in 17 patients; however, 12 patients showed ST-segment elevation. In only nine patients were the ST-segment changes seen to be associated with major changes in pulse or blood pressure. ST-segment changes were seen as frequently in patients with, as without, known cardiovascular disease. All patients had an uncomplicated postoperative course and no case of myocardial infarction was seen. ST-segment changes during elective surgery seem to be a common phenomenon. The etiology of the observed changes is not clear and its value in the detection of per- or postoperative myocardial ischemia needs to be further evaluated.

Aged↗