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Biomedical subjects

S E Smith

Publications and source records attributed to S E Smith.

At least 163 records · Page 9Linked to original sources
PubMed1988

Urinary lipoperoxides quantified by liquid chromatography, and determination of reference values for adults.

Urinary lipoperoxides, measured as the malondialdehyde-thiobarbituric acid adduct, were quantified by adapting to urine the liquid-chromatographic method of Wong et al. (Clin Chem 1987;33:214-20) to plasma. Reference intervals for untimed urine specimens from 121 men, ages 16 to 67 years, and 107 women, ages 15 to 55, were determined. Their concentrations differed significantly (P = 0.015), males having a mean (and SD) of 0.89 (0.35) nmol of malondialdehyde per milligram of creatinine, females 0.78 (0.30). In both groups, the values were slightly skewed to the higher values. Our early studies suggest that measuring urinary lipoperoxide may have advantages over plasma in studying certain disorders. The presence of other urinary chromophores or TBA-reactive substances stresses the need for chromatographic techniques when lipoperoxides are measured in biological samples.

Adolescent↗
PubMed1987

Uptake of 3H-deoxyglucose as a microassay of human neutrophil and monocyte activation.

The accumulation of 2-deoxy-D-[1-3H]glucose, a non-metabolised analogue of glucose provides a quantitative measurement of the state of activation of phagocytic cells. A microassay for 3H-deoxyglucose uptake by human neutrophils and monocytes is described. Optimal conditions for the assay include the use of 5 X 10(5) cells and 0.78 microCi/ml of deoxyglucose in a final volume of 0.2 ml per microtitre well, and an incubation time of 30 min at 37 degrees C. This simple, rapid and reproducible technique may find application in experimental immunology.

Cell Count↗
PubMed1987

Anterior segment fluorophotometry in acute anterior uveitis.

Anterior segment fluorophotometry was used to assess the severity of blood-aqueous barrier disruption in 25 patients with acute anterior uveitis. The results indicated that HLA-B27-positive patients had a more severe inflammation than did HLA-B27-negative patients, which was not discernible when judged by clinical signs and symptoms. Follow-up studies showed that the blood-aqueous barrier was disturbed for longer than the clinical signs indicated, and sometimes a temporary subclinical relapse was demonstrated on early withdrawal of topical therapy. The blood-aqueous barrier appeared to be restored after each attack of acute anterior uveitis in the majority of patients, with no evidence of progressive damage from repeated attacks. Our results indicated that fluorophotometry provides an objective and sensitive method of assessing anterior uveitis.

Acute Disease↗
PubMed1987

A test of possible cognitive and environmental influences on the mood lowering effect of tryptophan depletion in normal males.

In a previous study we found that a tryptophan-deficient amino acid mixture, designed to lower tissue tryptophan and thus brain 5-hydroxytryptamine (5HT) levels, caused a rapid (5 h) lowering of mood in normal males. Because of the importance of this evidence indicating a direct causal connection between low 5HT and low mood, we have now investigated other possible explanations for the mood lowering effect. Research strongly supports the involvement of environmental setting and cognition in the production and experience of emotions. Therefore we investigated how these factors might influence the mood-lowering effects of tryptophan depletion. In an instructional manipulation subjects were either supplied or not supplied with information designed to account for any possible peripheral sensations that might be related to depressive affect. In an environmental manipulation subjects were exposed either to a supportive and comfortable atmosphere (positive environment), or an unrewarding and unstimulating environment (negative environment). In the control group, which received a balanced amino acid mixture, the positive and negative environments had the expected effects on the scores of the Multiple Affect Adjective Checklist, thus indicating the effectiveness of these procedures. In the tryptophan depletion group neither the instructional nor the environmental manipulation had any influence on the mood lowering effect. It may be that tryptophan depletion lowers mood in normal males because low 5HT influences mood directly rather than via cognitive processes. Our data strongly support the idea that 5HT exerts an effect on mood and that low 5HT may, in some patients, be an important factor contributing to the etiology of clinical depression.

Adolescent↗
PubMed1987

The pharmacokinetics of indoramin and 6-hydroxyindoramin in poor and extensive hydroxylators of debrisoquine.

Five poor metabolisers (PM) and seven extensive metabolisers (EM), of debrisoquine, all healthy volunteers, received 50 mg indoramin orally following an overnight fast. Plasma concentrations of indoramin and 6-hydroxyindoramin were determined by HPLC with fluorimetric detection. In PM subjects, mean values of Cmax (158 ng/ml) and AUC(0-24) (2556 ng X h X m-1) for indoramin were substantially elevated and t 1/2 beta (18.5 h) prolonged by comparison with values in the EM subjects (21.6 ng/ml, 151 ng X h X ml-1 and 5.2 h respectively). For 6-hydroxyindoramin, on the other hand, Cmax (12.4 ng/ml) and AUC (0-8) (47.5 ng X h X ml-1) in PM subjects were significantly lower than in the EM subjects (28.2 ng/ml and 94.7 ng X h X ml-1). There was a tendency to a higher incidence of side-effects in the PM group. Although the difference did not achieve statistical significance (0.1 greater than p greater than 0.05), all the PM subjects experienced sedation compared to only two in the EM group. Differences in blood pressure and pulse rate between the two groups were small. It is concluded that the oxidative metabolism of indoramin is subject to genetic polymorphism, which is probably under the control of the same gene locus as that influencing debrisoquine oxidation. The clinical consequences are discussed.

Adult↗
PubMed1987

Effects of administering caffeine to pregnant rats either as a single daily dose or as divided doses four times a day.

From day 6 to day 20 of pregnancy, rats were treated with caffeine in a total daily dose of 10 or 100 mg/kg by gavage, either as a single bolus dose or as four divided doses given at 3-hr intervals throughout the day. Controls were given distilled water at the same times. Maternal body weight and food and water consumption were reduced in the two groups receiving a total of 100 mg caffeine/kg/day and in the group given 2.5 mg/kg four times daily. Dose-related decreases in foetal weight, placental weight and crown-rump length and dose-related retardation of skeletal ossification were observed. Major foetal abnormalities, mainly ectrodactyly, were seen only in the group given 100 mg caffeine/kg in a single daily dose.

Abnormalities, Drug-Induced↗
PubMed1987

Evidence for an inhibitor of leucocyte sodium transport in the serum of neonates.

1. In confirmation of previous studies, serum obtained from cord blood demonstrated endogenous digoxin-like immunoreactivity (EDLI). Sera from pregnant women in the third trimester also demonstrated EDLI, which disappeared after delivery. 2. Cord serum inhibited the total sodium efflux rate constant of a mixed leucocyte preparation when compared with the effect of control serum. This inhibition resulted from a depression of the ouabain-sensitive (sodium pump) component of the rate constant. 3. An ultrafiltrate of the serum (mol. wt. less than 30,000) also inhibited ouabain-sensitive leucocyte sodium transport when compared with filtrate obtained from control serum. 4. DHA-S Dehydroepiandrosterone sulphate (DHA-S) and cortisone, both present in high concentration in cord serum, demonstrated EDLI but did not affect leucocyte sodium transport in the cells of normal subjects. 5. DHA-S had no effect on sodium transport or vasoconstrictor activity in human omental resistance vessels. 6. It is concluded that EDLI of cord serum is associated with sodium transport inhibitory activity. This is unlikely to be attributable to DHA-S or cortisone.

Biological Transport↗
PubMed1987

Reference intervals for plasma lipoperoxides: age-, sex-, and specimen-related variations.

We measured lipoperoxides, as malondialdehyde (MDA), by liquid chromatography in plasma from 230 male and 148 female adult blood donors, to establish reliable reference values and to compare possible sex-, age-, and specimen-related differences. Our studies show that mean have higher MDA concentrations in plasma than do women (P less than 0.05), older men have higher values than younger men (P less than 0.05), and older women have higher values than young women (P less than 0.001). These age-related results support earlier studies in experimental animals that lipid peroxidation increases with increasing age. In addition, plasma from liquid EDTA-anti-coagulated blood has significantly lower MDA concentrations than does serum or plasma from blood treated with lithium heparin, sodium citrate, or CPDA-1 (P less than 0.001).

Adolescent↗
PubMed1986

Unexpected anterior urethral diverticula.

Most anterior urethral diverticula present in infancy with urinary obstruction or retention. When they present after infancy they do so with recurrent urinary tract infections or dribbling of urine. Three boys with late-presenting diverticula are described. Unless good oblique radiographs are specifically taken, with a fast flow, then the diagnostic arcuate filling defect of the proximal lip of the diverticulum can be missed. There may be few signs of obstruction. With diagnostic radiographs the urologist must be urged to repeat a negative cystoscopy. Diverticula must be differentiated from strictures or acquired diverticula following trauma.

Adolescent↗
PubMed1986

Typhlitis in acute childhood leukaemia: radiological features.

Typhlitis is a necrotising inflammation of the caecum usually found in acute leukaemic patients on chemotherapy. We described the radiological features of two children with this complication. The first was diagnosed by an enema using water-soluble contrast medium and the second by ultrasound and computed tomography (CT). A water-soluble contrast medium enema is considered diagnostic in this clinical context and excludes intussusception and, often, appendicitis. Ultrasound showed a rounded mass with dense central echoes and a wider hypoechoic periphery. Computed tomography showed the long segment of thick-walled ascending colon and caecum; if perforation is suspected, ultrasound and CT might be preferable to a contrast enema.

Cecal Diseases↗
PubMed1986

Beta-adrenoceptor antagonists increase sinus arrhythmia, a vagotonic effect.

The influence of vagal and sympathetic efferent activity on sinus arrhythmia in man has been studied in six healthy subjects by administration of hyoscine butylbromide and/or various beta-adrenoceptor blocking drugs using a microcomputer-linked electrocardiogram system. Sinus arrhythmia was quantitated as the s.d. of the R-R interval. Sinus arrhythmia was almost abolished by hyoscine butylbromide irrespective of the absence or presence and nature of the beta-adrenoceptor blocking drug. Atenolol and metoprolol alone prolonged the mean R-R interval and increased sinus arrhythmia. Oxprenolol, a drug with modest partial agonist or intrinsic sympathomimetic activity (ISA), prolonged the mean R-R interval to a lesser extent but had no effect on sinus arrhythmia. Xamoterol, which has high ISA, shortened the mean R-R interval but had no effect on sinus arrhythmia. These data yielded a non-linear relationship between sinus arrhythmia and mean R-R interval. Exaggerated sinus arrhythmia appears to accompany beta-adrenoceptor blockade only in the absence of ISA when bradycardia ensues. These findings are consistent with the hypothesis that the exaggeration in sinus arrhythmia is due to a central vagotonic effect secondary to the action of the drugs in the periphery. Changes in R-R interval induced by the adrenoceptor blocking drugs were altered to some extent by vagal blockade. This observation is consistent with the hypothesis that changes in heart rate induced by such drugs are determined in part by a change in vagal tone.

Adrenergic beta-Antagonists↗