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Biomedical subjects

J Hewitt

Publications and source records attributed to J Hewitt.

At least 109 records · Page 6Linked to original sources
PubMed1981

Fetal metabolic response to experimental placental vascular damage.

The fetal metabolic response to repetitive placental damage, produced by microsphere embolization of the uteroplacental circulation, was examined longitudinally in eight singleton fetal lambs and compared with similar data from seven controls. Significant morphometric fetal growth retardation was associated with an abrupt cessation of the normal increases in oxygen, glucose, and lactate uptake observed in the control animals. However, fetal blood levels and umbilical substrate quotients did not change. At the time of sacrifice, fetal oxidative metabolic rate was reduced significantly. The significance of these findings relative to intact fetal survival is discussed.

Animals↗
PubMed1981

Effect of anti-inflammatory drug administration in patients with rheumatoid arthritis. An endoscopic assessment.

A prospective endoscopic study was carried out in 65 patients with rheumatoid arthritis to assess the prevalence of gastroduodenal lesions on aspirin alone or aspirin plus another anti-inflammatory drug (n = 26). All patients were taking greater than or equal to 8 tablets aspirin/day for greater than or equal to 3 months. Drug therapy consisted of regular, buffered or enteric-coated aspirin +/- one other non-steroidal anti-inflammatory drug or less than or equal to 10 mg prednisone/day. Endoscopic findings were graded as normal, or gastric and/or duodenal erythema, erosions, or ulcer; only the most serious lesion was tabulated. Fifty-three percent of patients on aspirin alone has a gastric ulcer or erosions, and 13% duodenal ulcer or erosions compared to 35% with gastric lesions and 4% with duodenal lesions on aspirin plus a second drug. Twenty-two percent of patients taking regular aspirin had gastric ulcers compared to only 6% taking enteric coated. Patients on enteric coated aspirin and prednisone had only a 10% prevalence of severe gastro-duodenal lesions. In conclusion, the combination of a second anti-inflammatory drug and aspirin therapy did not result in a higher prevalence of gastro-duodenal damage over that produced by aspirin therapy alone. Enteric coated aspirin produced significantly fewer serious lesions than regular or buffered aspirin. The combination of enteric-coated aspirin plus low dose prednisone caused a low prevalence of severe gastro-duodenal lesions.

Anti-Inflammatory Agents↗
PubMed1981

Infective endocarditis-associated glomerulonephritis in rabbits: evidence of a pathogenetic role for antiglobulins.

Serial studies of circulating immune complexes, serum complement, proteinuria and renal histology and immunofluorescence have been undertaken in infective endocarditis glomerulonephritis in rabbits. Eighteen of 24 rabbits developed evidence of glomerulonephritis and 13 of 18 had circulating immune complexes. Gel filtration studies showed the immune complexes to have a size range of ca 4.10(6)--3.10(5) daltons. Direct immunofluorescence staining of glomeruli showed that IgM was the predominant immunoglobulin present and that antiglobulin activity was associated with IgM deposition. Intraglomerular localization of antiglobulin was closely associated with evidence of glomerulonephritis. Streptococcal antigen(s) were not demonstrable in glomeruli, even after acid elution of sections.

Animals↗
PubMed1980

Umbilical blood flow response to embolization of the uterine circulation.

The uterine and umbilical blood flow response to uteroplacental insufficiency, produced by microsphere embolization of the uteroplacental circulation, was examined by means of electromagnetic flow transducers in 12 pregnant ewes. No acute changes were observed in either circulation immediately after embolization of the uterine vasculature. Significant morphometric fetal growth retardation, in terms of weight, length, and ponderal index, was not associated with early changes in fetal pH, PO2, or PCO2. However, the incremental increases in both flows that were observed in control animals did not occur either during or after embolization because of an increase in vascular resistance. During and after embolization the incremental increase in uterine blood flow was blunted or decreased in most, but not all, animals. A rapid, progressive, and persistent decrease in umbilical flow occurred in the growth-retarded group. The significance of these findings relative to intrauterine growth is discussed.

Animals↗
PubMed1980

[Urticaria-oike follicular mucinosis (author's transl)].

Attention is drawn to a new clinical and pathological syndrome, part of the follicular mucinosis group, which is a cyclic, urticarial rash, of the head and neck, occurring in man, without follicular plugging and alopecia, and of benign course. 10 cases are presented here. All patients are middle aged men. Rash is pruritic and recurrent. Clinical aspects and histological findings are described.

Adult↗
PubMed1979

Antigen-specific suppressor factors produced by T cell hybridomas for delayed-type hypersensitivity.

This study describes the generation of T hybridoma lines which secret factors specifically suppressing delayed-type hypersensitivity (DTH) to sheep red blood cells (SRBC). AKR strain-derived T lymphoma BW 5147 cells were fused with spleen cells from mice primed with SRBC and containing antigen-specific T suppressor cells for DTH. Supernants from the derived hybridomas were tested for suppression of either expression of induction of DTH to SRBC. Six lines produced specific suppressor activity for the expression of DTH; 4 lines produced suppressor activity for the induction of DTH of which only one line was antigen-specific. These lines were passaged in normal AKR mice, and the serum obtained had activity up to 10(-4) dilution. The factor was effective across the H-2 barrier.

Animals↗
PubMed1979

Organization of the rosy locus in Drosophila melanogaster: further evidence in support of a cis-acting control element adjacent to the xanthine dehydrogenase structural element.

The present report summarizes our recent progress in the genetic dissection of an elementary genetic unit in a higher organism, the rosy locus (ry:3--52.0) in Drosophila melanogaster. Pursuing the hypothesis that the rosy locus includes a noncoding control region, as well as a structural element coding for the xanthine dehydrogenase (XDH) peptide, experiments are described that characterize and map a rosy locus variant associated with much lower than normal levels of XDH activity. Experiments are described that fail to relate this phenotype to alteration in the structure of the XDH peptide, but clearly associate this character with variation in number of molecules of XDH per fly. Large-scale fine-structure recombination experiments locate the genetic basis for this variation in the number of molecules of XDH per fly to a site immediately to the left of the XDH structural element within a region previously designated as the XDH control element. Moreover, experiments clearly separate this "underproducer" variant site from a previously described "overproducer" site within the control region. Examination of enzyme activity in electrophoretic gels of appropriate heterozygous genotypes demonstrates the cis-acting nature of this variation in the number of molecules of XDH. A revision of the map of the rosy locus, structural and control elements is presented in the light of the additional mapping data now available.

Crosses, Genetic↗
PubMed1979

[Knowledge of Solomon's epidermal nevus syndrome (author's transl)].

Solomon's epidermal nevus syndrome is a questionable entity, because of its clinical heterogeneity. Four cases are presented in this paper, with emphasis on the complex relationship between variable types of epidermal nevi and diverse kinds of associated nervous, ocular and bone abnormalities. Nevertheless, it is of practical interest to know the frequency and the variability of these ectodermal and mesodermal associated defects; whatever the epidermal nevus, a careful examination must be carried out, in search of ocular, nervous, bone and renal signs, and, less frequently, but more often than in other children, these patients seem to be exposed to visceral malignancies.

Adolescent↗
PubMed1978

Anxiety and classroom examination performance.

Studied classroom examination performance over the course of an entire semester as a function of (a) students' anxiety level (high, medium, low); (b) difficulty level of exam question (more vs. less difficult); (c) type of exam question (rote memory vs. generalization); (d) sex of S; and (e) intelligence level of S. As expected, there was a strong main effect of anxiety and a significant interaction between anxiety and item difficulty. The latter was consistent with the Hull-Spence formulation of learning and performance--as the habit strength of incorrect responses increases (i.e., as the items become more difficult), the superiority of low over high anxious Ss also should increase. When item difficulty was held constant, anxiety did not interact with type of exam question.

Achievement↗
PubMed1978

Structure analysis of small proteins by electron microscopy: valinomycin, bacitracin and low molecular weight cell growth stimulators.

Dark field electron microscopy was combined with optical filtering to study at high resolution the structure of the cyclopeptide antibiotics, bacitracin and valinomycin, and two proteins of unknown structure, LMW-CSA N and B, low molecular weight granulocyte colony stimulating activity isolated from medium conditioned with normal or leukemic leukocytes. For bacitracin and valinomycin the images faithfully represented the known structural features at a resolution of 0.5 nm or better, depicting a two-ring structure for bacitracin, as well as the position of the potassium ion in valinomycin. Both proteins of unknown structrue had at least one cyclic peptide portion. LMW-CSA N had a size of 2.0 nm, LMW-CSA B of 2.4 nm. A potential site of the calcium ionophoric activity in the latter protein was found to be in the larger of the two ring portions constituting the molecule.

Bacitracin↗
PubMed1978

[Menkes' disease (new skin and hair ultrastructural abnormalities) (author's transl)].

The authors report the sixth case of Menkes' kinky hair disease. This boy has been observed for as long as 16 months, and he his still alive at the time of publication. This genetic, X linked disorder of copper metabolism is always fatal in childhood. Diagnosis is evoked when is noted the conjunction of progressive cerebral degeneration, seizures, with pili torti and monilethrix. It can be asserted with the very low copper and cerulo-plasmin blood levels. Recognition of the disease in utero might be possible. New findings in skin' electron microscopy and hair' scanning electron microscopy are reported here. And two RX scanner of the brain have been performed.

Brain Diseases, Metabolic↗
PubMed1977

An investigation of mistranslation in vivo induced by streptomycin by an examination of the susceptibility of abnormal proteins to degradation.

Proteolysis rates in vivo were measured in Escherichia coli cultures during treatment with dihydrostreptomycin and under various other conditions. Dihydrostreptomycin treatment caused an increase in the proteolysis rate, compared to untreated controls. The proteolytic system in vivo responsible for the elevated proteolysis in the early stages of dihydrostreptomycin treatment, or that during canavanine and puromycin treatment, were not inhibited by addition of phenylmethanesulphonyl fluoride. This agent did inhibit proteolysis rates in cultures whose growth was inhibited by starvation, or had been completely stopped by dihydrostreptomycin. It seems, therefore, that the extremely high proteolysis rates in cultures at this stage of dihydrostreptomycin treatment were due to the action of two protease systems: the one concerned with the breakdown of abnormal proteins, and the other concerned with normal protein turnover and active during a non-specific decline of growth. The proteolytic rate at complete growth inhibition brought about by dihydrostreptomycin was intermediate between those induced by canavanine and puromycin at the same stage of treatment. This indicated a similar hierarchy in the extent and nature of abnormality in the proteins synthesized under these conditions. The relationship between the abnormality of proteins induced by dihydrostreptomycin and the importance of this in the antibiotic mechanism is discussed.

Bacterial Proteins↗