Search PubMed⌕ Search

Biomedical subjects

J D Smith

Publications and source records attributed to J D Smith.

At least 307 records · Page 17Linked to original sources
PubMed1981

Mesoionic xanthine analogues: phosphodiesterase inhibitory and hypotensive activity.

Several mesoionic thiazolo[3,2-alphapyrimidines and mesoionic 1,3,4-thiadiazol[3,2-alpha-pyrimidines were evaluated as inhibitors of cyclic-AMP phosphodiesterase. While small alkyl substituents at the 6 position have no significant effect on activity, phenyl and benzyl substituents enhance activity. Mesoionic structures such as 1 (R2 = H; R8 = Et) possess 20 to 40 times the activity of theophylline when the R6 substituent is phenyl or 4-chlorobenzyl. methyl and ethyl substitution at the 2 position essentially abolishes activity. Although plagued by solubility problems, several of the mesoionic derivatives were found to display weak hypotensive effects in vivo.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1981

Mesoionic purinone analogues as inhibitors of cyclic-AMP phosphodiesterase: a comparison of several ring systems.

Several simple alkyl and aralkyl derivatives of mesoionic thiazolopyrimidines (1) and mesoionic 1,3,4-thiadiazolopyrimidines (2) were found to possess theophylline-like activity as inhibitors of cyclic-AMP phosphodiesterase (PDE). Reduction of the C2-C3 double bond of 1 or replacement of the sulfur atom of 1 or 2 with an N-methyl group nearly abolishes activity. Optimal activity appears to be associated with a hydrophobic substituent at the N8 position. The five-membered ring of 1 can be replaced by a pyridine or isoquinoline nucleus without untoward effects. Preliminary kinetic data suggest that the type of enzyme inhibition produced by the mesoionic derivatives is similar to that observed for theophylline. Thus, several novel mesoionic ring systems display activity as inhibitors of cyclic-AMP PDE and can serve as lead compounds for further investigation.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1981

Individual differences in the classification of stimuli by dimensions.

In two experiments, adults differing in general mental abilities ("intelligence") were given multidimensional classification tasks: aural and visual free-classification tasks that allowed grouping of triads or trends by conflicting criteria of dimensional identity or overall similarity, and a speeded classification task that required the filtering of variation in an irrelevant dimension. Four principal results are reported: (a) Individual differences in the tendency to use similarity criteria in free classification were systematic across modalities and stimulus dimensions; (b) filtering performance, measured as the effect of irrelevant variation on speeded classification, did not correlate with free-classification performance (percent similarity responses); (c) the tendency to use similarity criteria in free classification was not correlated with intelligence; and (d) the amount of interference in speeded classification was correlated negatively with intelligence. The results taken together suggest that there are two dimensions of individual differences in perceptual analysis, one having to do with ability and the other with style or preference. This suggestion was supported by an additional analysis. The results also raise questions about the convergence of measures of multidimensional stimulus processing.

Discrimination Learning↗
PubMed1981

Epidemic keratoconjunctivitis caused by adenovirus type 8: epidemiologic and laboratory aspects of a large outbreak.

During late 1977 and early 1978, 192 cases of epidemic keratoconjunctivitis occurred in a community in central Georgia. In 86 of these cases, the patient had been exposed to a single ophthalmologist's office (physician A) 3-22 days before onset of illness. Patients considered as cases were more likely to have had invasive ophthalmologic procedures than non-cases (p < 0.001), and a linear relationship existed between the number of procedures performed and the attack rate (r = 0.91, p < 0.05). Adenovirus type 8 (AV8) was identified as the responsible pathogen by culture and/or antibody determination for 20 of these patients. Group-specific AV hexon antigen and type specific dodecon antigen were identified in four of seven ophthalmic solutions obtained from physician A's office. The outbreak stopped after proper control techniques were initiated.

Adenoviridae Infections↗
PubMed1981

Effects of canavanine treatment on herpesvirus morphogenesis in cultured cells.

L-Canavanine, a naturally occurring analog of arginine, effectively inhibited the morphogenesis of herpes simplex virus (HSV) and human cytomegalovirus (HCMV) when added at the time of infection, but allowed the expression of several cytopathic changes. Exposure to canavanine at progressively later times ultimately led to qualitatively normal virion maturation. Under no conditions were morphologically aberrant viral particles observed. However, HSV-infected cells treated at 3 h postinfection or later did contain distinctive cytoplasmic inclusions resembling HCMV dense bodies. Recovery experiments showed that HCMV-infected cells exposed to canavanine for 1-5 days could support normal viral morphogenesis when washed free of this agent.

Canavanine↗
PubMed1981

Cast-bracing for fractures of the femoral shaft. A biomechanical and clinical study.

A study was made of the mechanics of blood-bearing in a series of patients treated with a cast-brace for fracture of the distal femur. Knee hinges incorporating strain-gauges, a simple force-plate on the floor and a standardised weight-bearing test were used to record axial loads through the cast-brace itself and through the fracture during the phases of healing. The cast-brace carried loads of only 10 to 20 per cent of body weight and functioned mainly as an antibuckling hinged tube. Patterns of weight-bearing recovery showed that the fracture itself limited loads to safe levels. A measure of the recovery of strength at the fracture was determined and termed the "fracture load index". Graphs obtained in this way demonstrated four biomechanical phases of bony union which correlated well with the stages of clinical healing. The clinical application of these results have led to improvements in the design of braces and the use of a cylinder cast-brace for fractures of the distal half of the femoral shaft and of a new type of brace with a hinge at the hip attached to the thigh cast for fractures of the proximal shaft. A simple clinical test is described by which it is possible to monitor the healing of fractures in cast-braces.

Adolescent↗
PubMed1981

Diagnosis of nosocomial bacterial pneumonia in acute, diffuse lung injury.

Nosocomial bacterial pneumonia as a complication of acute, diffuse lung injury may be difficult to distinguish clinically from other pathologic processes. To determine the reliability of findings commonly used to diagnose pneumonia in this setting, we compared clinical predictions of bacterial pneumonia with postmortem histology. Pneumonia was present histologically in 58 percent of the study patients, 36 percent of whom had been thought to have only lung injury. Among patients who had only diffuse lung injury histologically, 20 percent were thought to have pneumonia by clinical evaluation. Overall, 29 percent of cases were misdiagnosed. Improved diagnostic techniques will be required before the efficacy of preventive or therapeutic measures for pneumonia in the setting of acute, diffuse lung injury can be accurately determined.

Acute Disease↗
PubMed1981

Effect of light and incubation temperature on production by species of Fusarium of metabolites toxic to larvae of Tenebrio molitor L.

Larvae of Tenebrio molitor L., Gembloux strain, race F, having an initial weight of 10 mg were reared for 4 weeks at 27 +/- 0.25 degrees C 65 +/- 5% relative humidity on rye seed incubated with single isolates of four strains of Fusarium. The fungi had been cultured in total darkness or in constant light at a temperature of 8, 14, 20 or 24 degrees C. Two isolates of Fusarium poae (Peck). Wollenw. (7450 and 7452) retarded growth more than the third isolate of this species or than the isolate of Fusarium accuminatum Ell. & Ev. Nutritional value of rye seed decreased with increasing temperature, but declined to a larger extent when Fusarium species were present than when they were absent. The results suggest that changes in weight and mortality of larvae are good criteria for determining toxicity of fungal metabolites in Insects.

Animals↗
PubMed1980

Nasal polymorphic reticulosis in a child.

The case of nasal polymorphic reticulosis in a child is presented. The patient, an 11-year-old adopted boy, complained of nasal stuffiness and pain. Perforation of the nasal septum and ulceration of the hard palate were evident on examination, and an irregular tumor in the nasal cavity was demonstrated by tomography. Biopsy specimen showed atypical lymphoreticular cells within mixed inflammatory infiltrates. He was treated with radiation followed by cyclophosphamide, mercaptopurine, and methotrexate sodium. Despite regression of the palate lesion and a 12-month symptom-free interval, he died of disseminated polymorphic reticulosis 1 1/2 years after diagnosis. We are unable to find a similar reported case in a child.

Child↗
PubMed1980

An additional role for the outer nuclear membrane in the morphogenesis of herpes simplex virus.

Ultrastructural study of MRC-5 cells infected by herpes simplex virus yielded several examples of physical continuity between the outer nuclear membrane and the envelope of viral particles in the perinuclear cisterna, suggesting a fusion between the two. Such virions would thus lose their envelope and enter the cytoplasm as naked capsids. Fusion first occurred at 6-8 h postinfection (p.i.), while naked cytoplasmic capsids appeared at 6 h p.i. Since nuclear membrane disruption was not observed until 24 h p.i., it is unlikely to account for the early appearance of these capsids. Thus, in addition to its other roles, the outer nuclear membrane may be involved in naked cytoplasmic capsid production via a fusion event.

Capsid↗
PubMed1980

Sodium requirements, balance and tissue composition of growing pigs.

The sodium requirements, balance, excretion, patterns and composition of some pig tissues were studied in two feeding trials and a balance trial followed by an additional feeding period with terminal tissue composition analysis. The growth of pigs fed a corn-soybean meal diet without added salt was severely restricted. Results confirm that a sodium requirement of .09% of the diet is adequate and that .20% NaCl supplementation is adequate for any natural diet for swine. Diets containing .065% sodium caused about a 25% reduction in growth when fed to 10-kg pigs but no significant reduction when fed to 27-kg pigs. Dietary retention was 96% for pigs fed .032% or .067% sodium. Retention was less per unit gain (gain was greater per unit sodium retention) fo9r pigs fed .032% sodium than for pigs fed .067% or more sodium. Those fed .032% sodium had a greater PCV after 1 week on trial and a smaller plasma sodium concentration after 2 weeks. The terminal tissue analyses showed that the pigs fed the lowest sodium diet had lower concentrations of sodium in plasma, muscle and bone, lower concentrations of chloride in plasma and muscle and a greater plasma potassium concentration. Crystal sodium of bone was not significantly affected.

Animal Nutritional Physiological Phenomena↗