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Biomedical subjects

W Stern

Publications and source records attributed to W Stern.

At least 55 records · Page 3Linked to original sources
PubMed1984

Umbilical velocity wave ratios in human pregnancy.

Umbilical artery velocity waves were measured in the fetuses from 130 pregnant women. One hundred eighty-five determinations were carried out from the fourteenth to the fortieth weeks of pregnancy. Detection of waveforms was carried out on an Angioscan Doppler spectrum analyzer. The umbilical artery velocity waves can be differentiated from other fetal signals by recognition of the pattern. The systolic peak of the velocity wave was divided by the end-diastolic value, thereby giving an S/D ratio. The use of a ratio overcomes the obstacle of not knowing the angle between the incident beam and the direction of motion. The umbilical velocity wave S/D ratio in normal pregnancies declines from 2.8 to 2.2 from 25 to 41 weeks. In pregnancies which result in a small-for-gestational age (SGA) fetus, the ratio is significantly higher, showing an average level of 3.8 at 29 weeks and declining to 3.0 at 40 weeks. Abnormal umbilical velocity wave values are seen in an SGA fetus, unexplained fetal death, poorly controlled diabetes mellitus, and a twin transfusion syndrome. Application of this technique has the potential of being an important aid in prenatal care.

Female↗
PubMed1984

Chronic low-dose levodopa therapy in Parkinson's disease: an argument for delaying levodopa therapy.

Levodopa is the most useful drug for treatment of Parkinson's disease today. But after continued use for several years, the effectiveness declines, and the undesirable side effects become more frequent, leading to unsatisfactory control. Once the treatment failure emerges, further management is difficult and often unsuccessful. One alternative for preventing side effects and treatment failure is to use a low dose. We are reporting our 12-year experience on uninterrupted treatment with levodopa, 3 grams (approximate) daily. The improvement was comparable with the best reports on higher dosage, and the side effects were significantly less frequent. The frequency of dyskinesia and on-off phenomena showed a strong correlation with duration of treatment. Psychiatric side effects were more common on treatment, but frequency of dementia did not correlate with duration of therapy. Improvement reached a peak after 6 months and remained statistically significant for 3.5 years. By the end of 5 years, the disability profile in the group was similar to that prior to levodopa treatment. So far, there is no satisfactory method for preventing treatment failure. From our observations, low dosage of levodopa is a desirable alternative, but not the answer to therapeutic failure. We recommend that levodopa use be delayed until the patient has a functional and/or psychological handicap that cannot be satisfactorily controlled with less potent antiparkinsonian agents.

Humans↗
PubMed1983

Regulation of the composition and positioning of saturated and monoenoic fatty acids in phosphatidylcholine.

The mechanism by which polyenoic acids control the amount and positioning of monounsaturated fatty acids in choline phosphoglycerides from baby hamster kidney cells was studied. Under normal growth conditions monoenoic acids were derived from the desaturation of saturated fatty acids and comprised over 50% of the fatty acids at position 1 of the glycerol moiety. The monoene content of positions 1 and 2 decreased in response to the addition of di- and polyenoic acids to the culture medium. All the di- and polyenoic acid supplements tested inhibited the desaturation of palmitic and stearic acid and replaced monoenes at position 2. However only linoleic, linolenic, and eicosadienoic acids replaced monoenes at position 1. The results suggest that under appropriate conditions up to 25% of the choline phosphoglyceride fraction consisted of a stable molecular species containing di- or trienoic fatty acids at both the 1 and 2 positions of glycerol moiety. With eicosatrienoic or arachidonic acid supplements, on the other hand, the monoenes at position 1 were replaced with saturated fatty acids. The magnitude of these effects, particularly at position 1, was proportional to the concentration of the fatty acid supplement. The results suggest that polyenes with at least 20 carbon atoms can play a key role in determining the ultimate composition and positioning of fatty acids in baby hamster kidney choline phosphoglycerides and that this control is mediated by their ability to inhibit delta 9 desaturase and by a retailoring system specific for these polyenes.

Acetates↗
PubMed1982

The role of hypersensitivity reactions to toxoplasma antigens in experimental ocular toxoplasmosis in nonhuman primates.

To assess the role of ocular hypersensitivity reactions to Toxoplasma antigens in previously sensitized ocular tissues, we used a nonhuman primate model of ocular toxoplasmosis. Each eye of eight monkeys was inoculated with living Toxoplasma organisms into the inner retinal layers. All eyes developed necrotizing retinochoroiditis. Healing of the lesion occurred with the formation of a retinochoroiditic scar. Four months later, Toxoplasma antigens were injected through the right internal carotid artery. Four weeks after this, Toxoplasma antigens were inoculated into the left retina. Iritis, vitritis, and retinal edema occurred in response to the administration of the antigens, but no recurrent necrotizing retinochoroiditis was produced in this model. These findings suggested that hypersensitivity to Toxoplasma antigens does not play a major role in triggering recurrences of toxoplasmic retinochoroiditis in nonhuman primates.

Animals↗
PubMed1980

Structure of a marsupial-mild trisaccharide.

A trisaccharide, which is a major carbohydrate component of the milk of the tammar wallaby and the grey kangaroo, has been identified by chemical, enzymic, g.l.c.-m.s., and n.m.r. methods as O-beta-D-galactopyranosyl-(1 yields 3)-O-beta-D-galactopyranosyl-(1 yields 4)-D-glucose (3'-galactosyl-lactose).

Animals↗
PubMed1979

Acalculous cholecystitis: results of cholecystectomy.

The results in a small series of patients with clinical cholecystitis, but who had no stones, on whom operation was performed are compared with results in a larger series of patients who had stones. The results suggest that, if a clinical diagnosis is made and other causes of symptoms have been excluded, the results of operation are almost as successful as in those having stones. Patients should not be denied operative relief if the symptoms strongly suggest gall bladder disease even if no stones are shown on X-ray examination.

Adult↗
PubMed1977

Biogenesis of poxviruses: analysis of the morphogenetic sequence using a conditional lethal mutant defective in envelope self-assembly.

A conditional lethal, temperature-sensitive mutant of vaccinia, defective in assembly of the virus envelope and maturation, was characterized and shown to mimic exactly the aberrations produced by rifampicin. Analyses of the infection at restrictive and permissive temperatures were conducted with electron microscopy, isotopic pulse-chase experiments in which polypeptides were separated by polyacrylamide slab gels, and assays of core enzymatic activities. The data collected by several approaches reveal that assembly and maturation of vaccinia involves a tightly coupled sequence of interrelated events including the assembly of the envelope, post-translational cleavage of several virion polypeptides, and induction of the core enzymes.

DNA, Viral↗
PubMed1976

Activity and properties of CTP: cholinephosphate cytidylyltransferase in adult and fetal rat lung.

Cholinephosphate cytidylyltransferase (CTP : cholinephosphate cytidylyltransferase, EC 2.7.7.15) is located in both the microsomal and supernatant fractions of adult lung when the tissue is homogenized in 0.145 M NaCl. The activity is located predominantly in the supernatant fraction in fetal lung. Cholinephosphate cytidylyltransferase in the supernatant from fetal lung is stimulated 4- to 6-fold by the additions of total lung lipid. Serine phosphoglycerides and inositol phosphoglycerides specifically caused stimulation whereas choline phosphoglycerides and ethanolamine phosphoglycerides produced no stimulation. Lysophosphatidylcholine cause some stimulation, but only at high concentrations. A number of detergents were investigated. All produced inhibition except for the ampholytic detergent, miranol H2M which was not inhibitory. None of the detergents produced any stimulation of activity. Cytidylyltransferase activity in fetal lung when assayed in the absence of lipid is about 25% of the adult. The activity when assayed in the presence of lipid is equal or slightly higher than adult levels. The activity, measured without added phospholipid, increases 5- to 6-fold within 12 h after birth, to values higher than in the adult. The activity, measured in the presence of phospholipid, increased almost linearly from -2 day until +1 day. There is an inverse relationship between the concentration of phospholipid in the fetal lung supernatant and the degree of lipid stimulation. Chromatographic experiments with Biogel A 1.5 columns have shown that cytidylyltransferase can exist in two molecular sizes, a small molecular size that requires phospholipid for activity, and a larger molecular weight species which does not require the addition of phospholipid for activity. Fetal lung has a higher proportion of the low molecular weight form than adult lung. The small molecular weight species can be converted to the larger molecular weight form by the addition of phospholipids.

Aging↗
PubMed1976

Colorectal schistosomiasis: report of three cases.

The facility for mass movement of segments of our world populations creates the need for physicians to recognize and manage diseases not seen in native patients. Such a need has occurred in New York City, where schistosomiasis, with its protean manifestations has been seen with increasing frequency. The cases of three patients who had different clinical manifestations of infestation by S. mansoni are presented. Clinical, radiologic, and pathologic features are discussed. To avoid delay in treatment, physicians must consider the possibility of this disorder in cases of patients from areas of endemic schistosomiasis.

Adult↗