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Biomedical subjects

R John

Publications and source records attributed to R John.

At least 127 records · Page 7Linked to original sources
PubMed1990

The clinical spectrum of staphylococcal bacteraemia: a review of 101 Melanesian patients from Papua New Guinea.

The clinical features of 101 Melanesian patients with Staphylococcus aureus bacteraemia observed during two 2-year periods (1977-1979 and 1985-1987) in a university teaching hospital in Papua New Guinea are reviewed. The age of the patients ranged from 12 to 70 years. There were 69 males and 32 females. Diabetes mellitus, found in 15 patients, was the most common predisposing factor. Most of the patients (87%) had community-acquired infection. Soft-tissue infection, pneumonia, arthritis, osteomyelitis, intravenous-site thrombophlebitis, cerebral abscess, endocarditis and cavernous sinus thrombosis were among the clinical entities observed. Soft tissues and lungs were the most common sites of primary and secondary foci of infection, respectively. All but 1 of the 101 blood isolates were resistant to penicillin G and none was resistant to methicillin. The overall case fatality rate was 24%. These data demonstrate that staphylococcal bacteraemia in adult Papua New Guineans is mostly community acquired and has a high mortality. Skin and soft tissues are the major primary foci of infection leading to staphylococcal bacteraemia.

Adolescent↗
PubMed1990

Concentrations of free thyroxin and free triiodothyronine in serum of patients with thyroxin- and triiodothyronine-binding autoantibodies.

Between 1982 and 1989 we identified 47 subjects with spuriously increased concentrations of free thyroxin (FT4) or free triiodothyronine (FT3) related to autoantibody interference in analog FT4 and (or) FT3 methods. The incidence of autoantibody interference observed during one year (1988) was 1 in 2460. In the subjects identified, 51% and 11%, respectively, showed an increased binding of radiolabeled T4 or T3 analog alone; 38% had an increased binding of both. Of 36 patients tested, 71% had autoantibodies to thyroglobulin and microsomal fraction of the thyroid, 19% to microsomal fraction alone, and 9.5% to thyroglobulin alone. In eight subjects, spuriously increased FT4 concentrations were reported with the following FT4 methods (in decreasing order of interference): Coat-A-Count, Amerlex-M, Amerlite, Seria, Magic Lite, Amerlex-MAB. In the same eight subjects, Amerlex-M and Seria reported spuriously increased concentrations of FT3.

Adolescent↗
PubMed1989

Growth hormone responses to growth hormone releasing factor in primary degenerative dementia.

The growth hormone (GH), thyroid-stimulating hormone (TSH), and prolactin (PRL) responses to growth hormone releasing factor (GRF) were investigated in 18 patients suffering from primary degenerative dementia (PDD) and in 20 age- and sex-matched normal elderly controls. There was no significant difference in the growth hormone response to GRF stimulation between patients and controls, and in neither subject group was there a demonstrable TSH or prolactin response to GRF. These findings indicate that the pathophysiology underlying the blunted growth hormone response to pharmacological challenge in PDD must lie at a suprapituitary level.

Aged↗
PubMed1989

Effect of nadolol on plasma lipids in hyperthyroidism.

The effect of Nadolol treatment on lipid subfractions in a group of 23 hyperthyroid patients was assessed in a randomised double-blind placebo controlled trial lasting six weeks, carbimazole being given to both groups from weeks 2 to 6. Clinical and biochemical euthyroidism was seen in both groups at 6 weeks; no effect of nadolol on peripheral monodeiodination of T4 to T3 was observed. At time 0 there were significant negative correlations between total cholesterol and free T3 (r = 0.68), and free T4 (r = 0.54). In the Nadolol group there were significant rises between 0 and 6 weeks in total cholesterol (52.6%, P less than 0.01), LDL cholesterol (30.3%, P less than 0.01) and HDL cholesterol (18.2%, P less than 0.05). HDL cholesterol rose significantly in the placebo group (12.4%, P less than 0.05) but there were no significant increases in LDL cholesterol or total cholesterol. The rise in triglyceride during this period in the Nadolol group (64.7%, P less than 0.05) was significantly greater (P less than 0.05) than the rise in the placebo group (8.8%). Nadolol increases triglyceride more than placebo during the early management of hyperthyroidism.

Adult↗
PubMed1989

The epicardial electrogram: a quantitative assessment during balloon angioplasty incorporating monophasic action potential recordings.

An electrogram was recorded from the angioplasty catheter guide wire when coronary blood flow was interrupted in 20 patients undergoing percutaneous transluminal coronary angioplasty. Monophasic action potentials were recorded from the right ventricular septum together with the routine electrocardiogram. The patients were studied during angioplasty for lesions in the left anterior descending (12), circumflex (3), and right coronary arteries (6). ST elevation in the electrogram recorded in the left anterior descending and circumflex systems was usually more obvious than that in the electrocardiogram. Signals obtained from the right coronary artery were of very low amplitude and registered only minimal ST changes. The ST elevation developed in the electrogram during insertion of the catheter before inflation of the balloon in 11 of the 15 patients undergoing angioplasty of the left system. In eight of the patients showing pre-inflation ST elevation the ST shift lessened after successive inflations. Monophasic action potential recordings were obtained during 45 balloon inflations in 19 patients. In those patients undergoing angioplasty for lesions of the circumflex coronary artery the monophasic action potential showed no change during balloon inflation. In patients undergoing angioplasty for the right coronary artery the mean normalised duration at 60 seconds' occlusion was 99.6 (1.5)% of control. Of a total of 25 occlusions in the patients undergoing angioplasty for the left anterior descending coronary artery 19 showed shortening of less than 5%, five showed shortening between 5 and 10%, and one showed a shortening of 16.4% in the monophasic action potential. The QT interval was satisfactorily measured in the electrogram during 36 balloon inflations, and in 24 of these it was also measured in the electrocardiogram. QT changes in the electrogram tended to be the opposite of those in the electrocardiogram. When changes in RR interval were minimal (less than 20 ms) during the balloon inflation 14 of 17 electrograms showed QT prolongation but only one of 12 electrocardiograms showed prolongation. Conversely one of 17 electrograms showed shortening compared with eight of 12 electrocardiograms. There was angiographic evidence of the development of collaterals in six of 15 patients undergoing angioplasty of the left system. ST segment elevation in both the electrogram and electrocardiogram was less pronounced in these patients than in those without evidence of the development of collaterals. ST segment changes recorded from the angioplasty guide wire provide a more sensitive index of ischaemia than the surface 12 lead electrocardiogram, and fall in ST segments on balloon deflation is a prognostic index of a good angiographic result in the left anterior descending and circumflex arteries, but not in the right coronary artery.

Action Potentials↗
PubMed1989

Antibody interference in a two-site immunometric assay for thyrotrophin.

Of 1585 consecutive serum samples referred for thyroid function testing, 14 gave erroneously high values from a two-site immunoenzymometric assay for thyrotrophin. The addition of mouse or newborn calf serum to the assay failed to correct the interference. In serum samples from 11 patients who were available for follow up a higher concentration of mouse, but not of horse, sheep or rabbit serum reduced the interference. The interference was associated only with assay systems which employed horseradish peroxidase but not 125I as a label. Addition of mouse serum and anti-IgM to the assay reagents successfully removed the interference.

Animals↗
PubMed1988

Postpartum thyroid dysfunction in Mid Glamorgan.

A high prevalence of postpartum thyroid dysfunction has been reported in several countries, but there have been no systematic studies of its prevalence in Britain. Among a group of 901 consecutive, unselected pregnant women thyroid autoantibodies were detected in 117 (13%) at booking. The clinical course of postpartum thyroid dysfunction, factors associated with its development, and its likely prevalence were defined in 100 of these women with thyroid antibodies and 120 women with no such antibodies who were matched for age. None of the women had a history of autoimmune thyroid disease. Normal reference ranges for thyroid function during pregnancy and post partum were established in the 120 women negative for thyroid antibodies. On the basis of these observations postpartum thyroid dysfunction was observed in 49 (22%) of the 220 women studied, and the prevalence in the total group of 901 women was estimated to be 16.7%. Thyroid dysfunction, mainly occurring in the first six months post partum, was usually transient and included both destruction induced hyperthyroidism and hypothyroidism. The development of the syndrome was significantly related to smoking more than 20 cigarettes a day and the presence of thyroid microsomal autoantibodies at booking. Of the 16 women with a family history of thyroid disease in whom thyroid microsomal autoantibody activity was detectable at booking, 11 developed thyroid dysfunction. Age, parity, presence of goitre at presentation, duration of breast feeding, and the sex and birth weight of the infant were not associated with the development of postpartum thyroid dysfunction. The mood changes experienced by women post partum may in part be associated with altered thyroid function during this time.

Adult↗
PubMed1988

Hypocholesterolemic effects of nicotinic acid and chromium supplementation.

During the course of a study of the hypoglycemic effects of nicotinic acid and chromium on humans, two hypercholesterolemic subjects were found to experience clinically significant decreases in serum cholesterol levels. These subjects have now been followed for one year. The first subject had a cholesterol level of 10.33 mmol/L (399 mg/dL). Daily supplementation for four weeks with 100 mg of nicotinic acid (niacin) and 200 micrograms of chromium chloride led to a decrease in serum cholesterol to 8.86 mmol/L (342 mg/dL). Further supplementation for four months led to a further decrease in serum cholesterol to 7.25 mmol/L (280 mg/dL). The second subject had a cholesterol level of 8.73 mmol/L (337 mg/dL). Four weeks of supplementation lowered the level to 6.73 mmol/L (260 mg/dL). When supplementation was discontinued, the cholesterol level rose slightly. When supplementation was reinstituted, the cholesterol level decreased to 6.68 mmol/L (258 mg/dL).

Cholesterol↗
PubMed1988

Evaluation of a new strategy for detection of thyroid dysfunction in the routine laboratory.

We assessed the use of a new strategy for detecting thyroid disorders, utilizing a sensitive assay for concentrations of thyrotropin (TSH) and free thyroid hormone in serum as follow-up tests. Of 1279 patients who were not on thyroxin (T4) replacement treatment, 82% could be classified as euthyroid and would require no further tests. In patients who were on T4 replacement, 41% fell into the euthyroid category and would require no further tests. Using this strategy to replace our existing strategy of free thyroxin as a "first-line" test would reduce the proportion of patients who would require one or more follow-up tests from 49% to 24%.

Evaluation Studies as Topic↗
PubMed1987

Multivariate analyses of the EEG in normal adolescents.

We investigated the computerized electroencephalography (cEEG) in a group of 85 normal adolescents. The spatial frequency of the cEEG was analyzed using various multivariate statistical techniques. The factor analyses revealed three factors that accounted for most of the variability in the data and that could be interpreted as a low versus high frequency, a beta frequency, and a frontal versus posterior factor. The cluster analysis revealed various EEG patterns that distinguished among subgroups of normal individuals.

Adolescent↗
PubMed1987

An enhanced serum prolactin response to TRH in the presence of GABA transaminase inhibition.

Patients with epilepsy were found to have an increased 20 minute prolactin response to intravenous TRH stimulation when receiving the GABA-T inhibiting drug vigabatrin. Enhanced GABA activity may either reduce basal prolactin levels whilst allowing a normal pituitary response to TRH stimulation, or may overcome the inhibitory effects of dopamine on pituitary prolactin release.

4-Aminobutyrate Transaminase↗
PubMed1987

Determinants of free theophylline clearance in asthma.

1. The free and total plasma and saliva concentrations of theophylline were measured during a dosing interval at steady state in nineteen asthmatic subjects receiving a once-daily theophylline preparation (Riker TCR-1). 2. Saliva theophylline clearance (mean +/- s.d. 5.8 +/- 2.1l h-1) was closely related to total plasma theophylline clearance (mean 3.6 +/- 1.2l h-1) (r = 0.958, n = 19, P less than 0.001). 3. Saliva theophylline clearance was closely related (r = 0.967, n = 19, P less than 0.001) and numerically very similar to the free plasma theophylline clearance (mean 5.8 +/- 1.9l h-1) (mean difference = 0.06 +/- 0.12 s.e. mean). 4. Free plasma theophylline clearance was significantly, although weakly, related to body weight and to the plasma free thyroxine concentration which together accounted for over 40 per cent of the variability in free clearance. 5. Theophylline administered for 2 weeks did not affect plasma free thyroxine (FT4) free tri-iodothyronine (FT3) or reverse tri-iodothyronine (rT3) concentrations compared with placebo.

Adult↗
PubMed1987

Non-adenomatous inappropriate TSH hypersecretion and euthyroidism requires no treatment.

The syndrome of inappropriate TSH secretion is described in a euthyroid girl and her father. Based on nuclear T3 binding studies in fibroblasts, generalized tissue resistance was associated with a lower binding affinity for T3 in nuclear extracts suggestive of a structurally abnormal receptor for T3. Early recognition of the syndrome and observation of the short-term response to thyroid medication prevented unnecessary trials of antithyroid medication and later radical ablative thyroid treatment.

Child, Preschool↗
PubMed1987

Thyroid status in senile dementia of the Alzheimer type (SDAT).

Thyroid function was investigated in a group of 21 patients with severe senile dementia of the Alzheimer type (SDAT) and in a group of 17 age and sex matched normal controls. Free thyroid hormone levels (triiodothyronine (T3) and thyroxine (T4) were measured, as were also the thyrotrophin (TSH), prolactin (PRL) and growth hormone (GH) responses to thyrotrophin releasing hormone (TRH)). When compared to controls, patients demonstrated a significantly lower free T3 value (but not free T4), a blunted TSH response to TRH, slightly elevated basal PRL and GH values and a small GH response to TRH. However, all differences were small in biological terms and were within the laboratory's normal range. This emphasizes the relative normality of neuroendocrine function, particularly thyroid status, in SDAT.

Aged↗
PubMed1987

Serum free thyroxine and free triiodothyronine concentrations in healthy fullterm, preterm and sick preterm neonates.

There are few data available on free thyroid hormone concentrations in the early neonatal period. With the widespread application of screening procedures for detecting congenital hypothyroidism there is a need for reference ranges in neonates. In this study we have evaluated thyroid function in healthy fullterm and preterm neonates, and sick neonates all within one to 10 days postnatal age. Our data indicates that free thyroxine but not free triiodothyronine is higher in fullterm neonates than the adult reference range and that both free thyroid hormone concentrations are reduced in healthy and sick preterm neonates as compared to fullterm neonates. Assessment of thyroid function in the early neonatal period needs to take into account these changes particularly in preterm and sick preterm neonates.

Female↗
PubMed1987

The effect of nadolol on heart rate in hyperthyroidism. A controlled trial.

Twenty hyperthyroid patients were randomly assigned in a double-blind fashion to receive either nadolol 80 mg/day or placebo for 2 weeks; all patients then took carbimazole as well from 2-6 weeks. Twenty-four hour Holter ECG recordings at 0, 2 and 6 weeks showed that nadolol reduced the mean maximum heart rate by 19.9% (P less than 0.0005) at 2 weeks and by 30.3% (P less than 0.0005) at 6 weeks compared to 5.2% (ns) and 18.3% (P less than 0.0005) in patients taking placebo. There was no alteration of the normal circadian variation of heart rate by nadolol. The minimum heart rate before therapy was significantly correlated with FT4 (r = 0.52) and with FT3 (r = 0.44). The percentage of time per hour during which the heart rate was greater than 100 was reduced by 79% at week 2 by nadolol compared to 22% in the placebo group. At the 6 week point the placebo group still had a tachycardia (mean maximum heart rate 101.6 beats/min +/- 15.2 SD) compared to the nadolol group (80.4 +/- 7.7). Nadolol did not cause excessive bradycardia. It is effective in the early management of hyperthyroidism and should be given for at least the first 4-6 weeks.

Adult↗