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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
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↗
PubMed1989

Safety and efficacy of three oral rehydration solutions for children with diarrhoea (Edinburgh 1984-85).

Of 357 children with acute diarrhoea admitted to the City Hospital, Edinburgh, over a 12-month period, only 5 (1.4%) required IV infusions. Three hundred and nineteen were treated with oral rehydration (OR). Of these 269 were studied in detail and 43% had signs of dehydration, but in none of them was it severe. There were no fatalities. Patients were randomly allocated to treatment with one of three OR solutions in a double blind trial. The solutions had sodium concentrations of 35, 50 and 90 mmol (mEq)/l, and dextrose of 200 (36 g/l), 111 (20 g/l) and 110 (19.8 g/l) mmol/l, respectively. Hypernatraemia was not a clinical problem and only 5 children (2%) were biochemically hypernatraemic on admission. Treatment did not cause clinical hypernatraemia. At the second assessment only 3 children were biochemically hypernatraemic, one from each treatment group, and no one had clinical signs. All three solutions were safe and effective in the relatively mildly dehydrated patients currently seen in the UK.

Child↗
PubMed1988

Stimulus-response coupling in marine sponge cell aggregation: lipid metabolism and the function of exogenously added arachidonic and docosahexaenoic acids.

Cells of the marine sponge, Microciona prolifera, the most ancient of the animal cells which clump on recognition, resemble neutrophils and platelets in undergoing stimulus-response coupling when exposed to Ca2+ ionophores and phorbol esters. We have studied lipid content and remodelling in sponge cells by thin-layer, gas-liquid, and high-performance liquid chromatography (HPLC) analyses supplemented by ultraviolet and mass spectroscopy. Phosphatidylcholine (PC) (35.6%), phosphatidylethanolamine (PE) (27.4%) and phosphatidylserine (PS) (21.4%) constituted the bulk of phospholipids detected. The major fatty acids were all polyenoic; 22:6 (22%), 26:2 (17%) and 26:3 (15%). Arachidonic acid (20:4), present as 2.7% of total phospholipid, and docosahexanoic acid (22:6) were found to elicit aggregation of sponge cells when added (10 microM) in synergy with ionomycin (1 microM), resembling in their effects those of phorbol esters (but not phorbol) and 1-oleyl-2-acetylglycerol (OAG). Moreover, 20:4 and 22:6, as well as phorbol ester and OAG, overcame the block to aggregation imposed by colchicine and vinblastine. Kinetic studies of lipid remodelling showed that aggregating cells diverted [14C]22:6 or [14C]20:4 from triacylglycerol into diacylglycerol and phospholipids; appearance of label in phosphatidic acid and phosphatidylinositol (PI) anteceded labeling of phosphatidylcholine. In unstimulated cells, [14C]22:6 was rapidly incorporated into phosphatidylcholine with little accumulation in phosphatidate. Although 22:6 and 20:4 resembled OAG and phorbol esters in overcoming the effects of colchicine and vinblastine (which had no effects on overall lipid metabolism), they did not reverse the block to aggregation of nordihydroguaiaretic acid (NDGA) (which inhibited lipid metabolism). Under none of these circumstances was 22:6 or 20:4 converted to cyclooxygenase or lipoxygenase products in the course of aggregation: all labeled acyl groups remained present as unmodified fatty acids on alkaline hydrolysis. These data not only extend the observations of Muller et al. (J. Biol. Chem. 262 (1987) 9850-9858) on the role of phosphoinositides and C kinase in marine sponge cell aggregation, but also demonstrate that sponges form diacylglycerols in the process. We suggest that exogenous 22:6 and 20:4 (like phorbol esters or OAG) can substitute for endogenous diacylglycerol in the activation of protein kinase C.

Animals↗
PubMed1988

Mapping from GenBank to MEDLINE.

GenBank has been based largely on literature that provides nucleic acid sequences. To find additional literature that is relevant to a given sequence, a search of MEDLINE can prove helpful. This paper documents some of the similarities between GenBank and MEDLINE that facilitate retrieval of documents from MEDLINE. In particular, techniques and examples are presented which take GenBank information and lead to MEDLINE information that supplements the GenBank information.

Abstracting and Indexing↗