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Biomedical subjects

M Stern

Publications and source records attributed to M Stern.

At least 217 records · Page 12Linked to original sources
PubMed1991

A multidisciplinary program to improve the teaching skills of incoming housestaff.

Residents at the School of Medicine and Biomedical Sciences at the State University of New York at Buffalo (SUNY at Buffalo) expressed an interest in receiving instruction in teaching skills. In 1988, under sponsorship of the Graduate Medical-Dental Education Consortium, faculty and residents implemented an orientation program for 110 incoming housestaff. Residents received instruction in large-group teaching skills, bedside teaching, small-group discussion, and student evaluation. The program was rated positively by the residents, 5% of whom became instructors in the orientation program for the following year. Because of the program's structure, both faculty and housestaff receiving training in teaching skills, which may lead to an overall improvement in the teaching of SUNY at Buffalo's medical students.

Attitude of Health Personnel↗
PubMed1991

Generation of Pseudomonas aeruginosa aerosols during handwashing from contaminated sink drains, transmission to hands of hospital personnel, and its prevention by use of a new heating device.

Pseudomonas aeruginosa was isolated from sinks of washing basins, showers, toilets and bathtubs, from the personnel and patients of a mixed infectious disease ward in a German children's hospital during a prospective 4-week epidemiological study. 81% of all sinks were contaminated with P. aeruginosa strains. Upon entering the hospital, all personnel hand cultures were P. aeruginosa-negative. However, during duty, 42.5% of the personnel members carried different P. aeruginosa strains on their hands. Detection of P. aeruginosa strains in sinks preceding the isolation of identical genotypes from personnel hands suggested a transmission route from sinks to hands. Opening of water taps generated aerosols containing P. aeruginosa sink organisms which contaminated hands during hand washing. Survival times of various P. aeruginosa strains in aerosols was dependent on strain characteristics, light and humidity, and t 1/2 differed between 3-76 min. Heating of washing basin sinks to 70 degrees C with a new, safe and inexpensive device inhibited bacterial growth in sinks, generation of P. aeruginosa aerosols, and resulted in hand cultures negative for P. aeruginosa after washing.

Aerosols↗
PubMed1990

Glycinamide ribonucleotide synthetase from Escherichia coli: cloning, overproduction, sequencing, isolation, and characterization.

The purD gene of Escherichia coli encoding the enzyme glycinamide ribonucleotide (GAR) synthetase, which catalyzes the conversion of phosphoribosylamine (PRA), glycine, and MgATP to glycinamide ribonucleotide, MgADP, and Pi, has been cloned and sequenced. The protein, as deduced by the structural gene sequence, contains 430 amino acids and has a calculated Mr of 45,945. Construction of an overproducing strain behind a lambda pL promoter allowed a 4-fold purification of the protein to homogeneity. N-Terminal sequence analysis and comparison of the sequence with those of other GAR synthetases confirm the amino acid sequence deduced from the gene sequence. Initial velocity studies and product and dead-end inhibition studies are most consistent with a sequential ordered mechanism of substrate binding and product release in which PRA binds first followed by MgATP and then glycine; Pi leaves first, followed by loss of MgADP and finally GAR. Incubation of [18O]glycine, ATP, and PRA results in quantitative transfer of the 18O to Pi. GAR synthetase is very specific for its substrate glycine.

Amino Acid Sequence↗
PubMed1990

Effect of topically administered epidermal growth factor on corneal wound strength.

A 9-mm perforating corneal wound was created in one eye of New Zealand albino rabbits, sutured, and treated with mouse-derived epidermal growth factor (1 mg/L), human-derived epidermal growth factor (1.0 mg/L to 100 mg/L), or buffered saline, instilled once, twice, or four times daily. Both mouse-derived epidermal growth factor and human-derived epidermal growth factor significantly increased the tensile strength of full-thickness corneal wounds after 9 days of topical therapy. For human-derived epidermal growth factor, a concentration of 10 mg/L administered twice daily produced the maximal effect. An increase in either the concentration of epidermal growth factor or its frequency of administration failed to induce a further increase in wound strength. Indeed, at a concentration of 100 mg/L, human-derived epidermal growth factor appeared to lose its ability to accelerate healing of full-thickness corneal wounds.

Administration, Topical↗
PubMed1990

Dosage effects of a Drosophila sodium channel gene on behavior and axonal excitability.

The effects of para mutations on behavior and axonal excitability in Drosophila suggested that para specifically affects sodium channels. This hypothesis was confirmed by molecular analysis of the para locus, which demonstrates that the encoded para product is a sodium channel polypeptide. Here we characterize the effects of altered para+ dosage on behavior and axonal excitability, both in an otherwise wild-type background and in combination with two other mutations: napts, which also affects sodium channels, and ShKS133, which specifically affects potassium channels. Whereas it was previously shown that decreased dosage of para+ is unconditionally lethal in a napts background, we find that increased dosage of para+ suppresses napts. Similarly, we find that para hypomorphs or decreased dosage of para+ suppresses ShKS133, whereas increased dosage of para+ enhances ShKS133). The electrophysiological basis for these effects is investigated. Other genes in Drosophila that have sequence homology to sodium channels do not show such dosage effects, which suggests that the para+ product has a function distinct from that of other putative Drosophila sodium channel genes. We conclude that the number of sodium channels present in at least some Drosophila neurons can be affected by changes in para+ gene dosage, and that the level of para+ expression can strongly influence neuronal excitability.

Animals↗
PubMed1990

Food proteins and maturation of small intestinal microvillus membranes (MVM). III. Food protein binding and MVM proteins in rats from newborn to young adult age.

To investigate postnatal maturational profiles of functional and biochemical properties of rat small intestinal microvillus membranes (MVM), we did a longitudinal study in rats from birth to the age of 12 weeks. In parallel, we studied binding of cow's milk proteins and of the wheat gliadin peptide B 3142, as well as MVM proteins (SDS-PAGE). Changes in MVM fluidity and lipid composition exhibited early (0-4 weeks) and intermediate and late (6-12 weeks) patterns, as has been published earlier. Postnatal changes of food protein and peptide binding occurred early during the observation period, not related to weaning. There was not much further change in binding after 6-8 weeks. Developmental profiles of MVM protein and some lipid changes resembled, but did not equal, changes in food protein binding. We conclude that changes in MVM biochemical composition affect MVM binding characteristics. In particular, high molecular weight MVM proteins (susceptible to trypsin treatment) appear to play a role in postnatal maturational differences in MVM food protein binding.

Aging↗
PubMed1990

Neonatal and adult patterns of lectin binding to rat small intestinal microvillus membranes.

To investigate postnatal developmental changes of rat small intestinal microvillus membrane (MVM) sugar components, binding studies were done using peanut agglutinin (PNA) and soybean agglutinin (SBA). MVM were prepared from rats of different ages (new-borns to 12 weeks). The Airfuge method was used for separation of unbound material. Characteristics of sugar ligand specificity were different for PNA and SBA, although D(+)galactose was used as an inhibitor for both lectins. Concentration curves and Scatchard plots showed partial saturation of total binding, and at least two groups of MVM ligands. Differences in lectin binding between newborn and adult MVM were opposite for PNA and SBA (newborns bound more PNA, but less SBA). During the first few postnatal weeks in rats, SBA binding changed early, and PNA binding exhibited an intermediate change, not related to weaning. Changes in MVM glycoproteins shown by lectin binding appear to be part of a complex postnatal maturational process in rats, involving different biochemical, functional, and biophysical membrane characteristics.

Analysis of Variance↗
PubMed1989

[Continuous high-dose corticosteroid pressured aerosol therapy in steroid-dependent asthma].

Two therapeutic trials aimed at determining whether a high-dose inhaled corticosteroid, beclomethasone dipropionate (BDP), could reduce or suppress a long term and continuous treatment with a systemic corticosteroid, triamcinolone acetonide (TA), were carried out in a homogeneous population of severe, steroid-dependent asthmatics. The first one was a controlled, double-blind versus placebo trial involving 25 patients followed up for 5 months. The second one was an open trial involving 105 patients followed up for 12 months. In both trials the mean doses of TA were reduced by 60 to 65 per cent, and TA could be totally or nearly totally suppressed in almost 60 per cent of the cases with clinical and functional results that were equal or superior to those previously obtained with systemic corticosteroid therapy. It is concluded that: (a) continuous systemic corticosteroid therapy in mean doses of more than 5 mg/day of prednisone equivalent is now rarely indicated in patients with steroid-dependent asthma, and (b) inhaled corticosteroid therapy with BDP could be extended to cases of non steroid-dependent asthma inadequately controlled by bronchodilators.

Administration, Inhalation↗
PubMed1989

Fragmentation of bile duct stones by extracorporeal shock waves. A new approach to biliary calculi after failure of routine endoscopic measures.

A prospective uncontrolled multicenter trial was performed on 113 patients with bile duct stones in whom routine endoscopic approaches for removal of the calculi had failed. These represented 8.3% of the patients referred to the participating centers for endoscopic extraction of the stones. Extracorporeal shock-wave lithotripsy using the Dornier kidney lithotripter achieved stone disintegration in 103 patients (91%). Complete stone clearance from the bile ducts was obtained in 97 patients (86%) after a median of 4 days following extracorporeal shock-wave lithotripsy. Adverse effects, mostly mild, occurred in 36% of the patients. A 30-day mortality rate of 0.9% (in-hospital mortality rate = 1.8%) of this high-risk group with a mean age of 72 yr and a cholangitis rate of 26% compared favorably with the data given for open surgery. We therefore consider extracorporeal shock-wave lithotripsy a useful method for the treatment of bile duct stones not amenable to routine endoscopic measures.

Aged↗
PubMed1989

Childhood cancer stereotype: impact on adult perceptions of children.

Explored the possibility that biased expectations might affect how adults respond to children diagnosed as in remission from cancer. The presence of a childhood cancer stereotype was investigated experimentally by assessing reactions of undergraduates and medical students to children described with either an in remission from leukemia label (RLL) or healthy label (HL). RLL children were rated as less sociable, less cognitively competent, less behaviorally active and well behaved, less physically potent, littler, and less likely to adjust well to the future than HL children. Undergraduates and medical students generally did not differ in their ratings of RLL and HL children. Medical students reported that they were more familiar with childhood cancer than undergraduates; however, familiarity was not related to ratings of the RLL or HL children. Implications for further research and health education practices are considered.

Adult↗
PubMed1989

Altered synaptic transmission in Drosophila hyperkinetic mutants.

Synaptic transmission in Drosophila can be altered by mutations in specific genes. For example, mutations in the Shaker (Sh) gene, which encodes the rapidly inactivating A-type potassium channel, cause repetitive nerve firing and prolonged transmitter release at the neuromuscular junction. Here we show that mutations in the Hyperkinetic (Hk) gene also affect the properties of synaptic transmission at the neuromuscular junction. In particular, we find that whereas single or low frequency nerve stimulation evokes a wild type postsynaptic response, at higher frequencies of nerve stimulation, each stimulus results in repetitive nerve firing and increased postsynaptic response, which is similar to that observed in Sh mutants. Various experiments suggest that this increased postsynaptic response results from prolonged depolarization of the nerve terminal, leading to increased transmitter release at the neuromuscular junction. The similarity in phenotypes between Sh and Hk mutants, along with the observation that Sh is epistatic to Hk in its effects on synaptic transmission, suggest that Hk acts on synaptic transmission by an effect on A-type potassium channels.

Animals↗
PubMed1989

Thrombolytic treatment of acute pulmonary embolism.

Many investigators have reported about beneficial results with thrombolytic therapy in patients with acute pulmonary embolism. Streptokinase and urokinase have been used for more than 15 years, but the conditions of use of these agents still remain controversial. Optimal dosage and treatment schedule are still evolving. For streptokinase most investigators adopt a fixed dosage schedule: a loading dose of 250,000 units followed by a maintenance infusion of 100,000 units per hour for 24 to 72 hours. For urokinase numerous dosage regimens have been used such as: high dosage schedule 4,400 units per kilogram per hour for twelve to 24 hours with or without loading dose; moderate dosage 1,600 to 2,000 units per kilogram per hour for 24 hours and low dosage in bolus. With these treatments there is a trend to reduced in-hospital-mortality in massive pulmonary embolism; the early pulmonary revascularization and the hemodynamic improvement are higher than those noticed with heparin. These results are obtained with a minimum of complication essentially bleeding in 10 or 15%; most bleeding being located at puncture site. More recently, new thrombolytic agents have been used in acute pulmonary embolism. Only four studies have tested rt-PA which is effective and relatively safe, but the optimal dose regimens remain to be determined. Less information is available concerning Anisoylated Plasminogen Streptokinase Activator Complex (APSAC), the angiographic improvement seems to be rapid and important (50% on average) but the decrease of fibrinogen is important too and comparable with streptokinase. Considering the good results of thrombolytic treatment of acute submassive and massive pulmonary embolism, there is a doubt as to whether the pulmonary embolectomy has any place in the pulmonary embolism patients except in those with cardiac arrest. In the near future new thrombolytic drugs could be more efficient on pulmonary embolism and deep venous thrombosis, and thus the bleeding risk might be decreased.

Acute Disease↗
PubMed1989

[Secondary carbohydrate and protein intolerances following gastroenteritis].

After acute gastroenteritis, delayed recovery and protracted diarrhoea may occur, particularly in very young infants, in bottle-fed malnourished infants, and after rota virus infection. Monosaccharide and disaccharide malabsorption have been demonstrated to contribute to postenteritis problems in these children. The contribution of secondary food protein intolerance to the perpetuation of diarrhoea after gastroenteritis is less well understood. Secondary sugar intolerance is diagnosed by estimation of stool pH, Clinitest, H2 breath testing and, in some cases, direct enzyme determination from biopsy material. Diagnosis of secondary cow's milk or soy-protein intolerance has to be done by clinical challenge. Dietary therapy consists of elimination of the malabsorbed food compound. A general elimination diet (lactose-free protein hydrolysate formula) is not necessary in the majority of cases but may be life-saving in individual infants. In West European countries postenteritis problems have become less in quality and quantity during the last few years.

Diarrhea, Infantile↗
PubMed1988

Membrane fluidity and lipid composition of rat small intestinal brush-border membranes during postnatal maturation.

Fluidity and lipid composition of rat small intestinal brush-border membranes (BBM) were studied during maturation in five age groups: newborns, sucklings (1-3 weeks), weaned (4-6 weeks), juveniles (8-10 weeks), and adults (12 weeks). Brush-border membrane fluidity was measured by steady-state fluorescence polarization. Fluorescent probes used were: 1,6-diphenyl-1,3,5-hexatriene, 1-(4-trimethylammonium)phenyl)-6-phenyl-1,3,5-hexatriene, and a set of n-(9-anthroyloxy) fatty acids. Fluorescence anisotropy measured with all fluorophores was increased in adult versus newborn rats (P less than 0.004). The weight ratio of saturated to cis-unsaturated fatty acids increased from birth to the suckling age (P less than 0.0004). The cholesterol to phospholipid molar ratio increased from birth to the weaned age (P less than 0.0001). Cholesterol to protein ratio and phospholipid to protein ratio decreased after the weaned age (P less than 0.004). The results not only describe maturational changes of brush-border membranes but also give a better understanding of the correlations between biophysical and biochemical data in biological membranes.

Animals↗
PubMed1988

Effects of cyclosporin on T-cell subsets in human immunodeficiency virus disease.

Cyclosporin (7.5 mg/kg daily) was given to 8 AIDS patients for 17-66 days and to 25 HIV-seropositive non-AIDS patients, 15 with stage II (T4 cells/microliter greater than or equal to 300, less than 600) and 10 with stage III (T4/microliter less than 300), for 3-6 months with the hypothesis that the drug could inhibit both HIV replication and the potential autoimmune component of HIV disease. A sustained increase over 600 T4/microliter occurred in 7 patients with stage II and 1 with stage III. T8 cells significantly decreased in most patients and lymphadenopathy disappeared in 14/16. After cyclosporin withdrawal T4 and T8 cells as well as lymphadenopathy returned to pretreatment status. Cyclosporin side effects (hypertension, creatinine increase, and anemia) were moderate and reversible. These results might stimulate biological research as well as clinical trials with cyclosporin in selected groups of HIV-seropositive subjects with the aim of delaying or preventing AIDS occurrence.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Central giant cell granuloma of the jaws: experiences in the management of thirty-seven cases.

This report reviews experiences in the management of 37 cases of central giant cell granuloma of the jaws. The statistical analysis includes location, age, sex, size on initial presentation, and other variables relating to incidence and distribution. The technique of curettage or curettage with peripheral ostectomy was used in all cases treated surgically, resulting in no evidence of disease in 21 out of 23 cases followed postoperatively for 2 or more years. Radiation therapy was curative in one instance. Preoperative endodontic therapy for teeth in the field of surgery has proved to be advantageous. The pathogenesis of the giant cell granuloma of the jaws is discussed.

Adolescent↗