PubMed Health⌕ Search

Biomedical subjects

P M Clark

Publications and source records attributed to P M Clark.

At least 19 recordsLinked to original sources
PubMed1992

Relation of infant feeding to adult serum cholesterol concentration and death from ischaemic heart disease.

OBJECTIVE: To examine whether method of infant feeding is associated with adult serum lipid concentrations and mortality from ischaemic heart disease. DESIGN: Follow up study of men born during 1911-30. SETTING: Hertfordshire, England. SUBJECTS: 5718 men, for 5471 of whom information on infant feeding had been recorded by health visitors and 1314 of whom had died. 485 of the men born during 1920-30 and still living in Hertfordshire who had blood lipid measurements. MAIN OUTCOME MEASURES: Death from ischaemic heart disease; serum cholesterol and apolipoprotein concentrations. RESULTS: 474 men had died from ischaemic heart disease. Standardised mortality ratios were 97 (95% confidence interval 81 to 115) in men who had been breast fed and had not been weaned at 1 year, 79 (69 to 90) in breast fed men who had been weaned at 1 year, and 73 (59 to 89) in men who had been breast and bottle fed. Compared with men weaned before one year men not weaned had higher mean serum concentrations of total cholesterol (6.9 (not weaned) v 6.6 (weaned) mmol/l), low density lipoprotein cholesterol (5.0 v 4.6 mmol/l) and apolipoprotein B (1.14 v 1.08 g/l). Men who had been bottle fed also had a high standardised mortality ratio for ischaemic heart disease (95; 68 to 130) and high mean serum concentrations of total cholesterol (7.0 mmol/l), low density lipoprotein cholesterol (5.1 mmol/l), and apolipoprotein B (1.14 g/l). In all feeding groups serum apolipoprotein B concentrations were lower in men with higher birth weight and weight at 1 year. CONCLUSIONS: Age of weaning and method of infant feeding may influence adult serum low density lipoprotein cholesterol concentrations and mortality from ischaemic heart disease. Adult serum apolipoprotein B concentrations are related to growth in fetal life and infancy.

Age Factors↗
PubMed1992

Hyperproinsulinaemia in patients with myotonic dystrophy.

Hyperinsulinaemia is a reported feature of the inherited multisystem disorder myotonic dystrophy. This phenomenon has been attributed to a compensatory beta cell response to tissue insulin resistance. In this study, circulating concentrations of insulin, proinsulin, and split proinsulin molecules were determined after an overnight fast in ten patients with myotonic dystrophy using two-site monoclonal antibody-based immunoradiometric assays. Results were compared with ten healthy control subjects matched for age, gender, and body mass index. Oral glucose tolerance (75 g), as defined by World Health Organization criteria, was normal in all subjects. Fasting plasma immunoreactive insulin concentration, as determined using a conventional radioimmunoassay, was almost three times higher (p < 0.005) in the myotonic dystrophy patients than the healthy control subjects. By contrast, fasting concentrations (mean +/- SEM) of C-peptide (0.75 +/- 0.09 vs 0.52 +/- 0.03 nmol/l, p = 0.07) and immunoradiometrically-determined insulin (60 +/- 12 vs 38 +/- 4 pmol/l, p = 0.09) were not significantly different between the groups. Fasting concentrations of proinsulin (10.3 +/- 2.9 vs 1.6 +/- 0.3 pmol/l, p < 0.01), and 32-33 split proinsulin (7.8 +/- 2.5 vs 2.9 +/- 0.4 pmol/l, p < 0.05) were significantly elevated in the patients with myotonic dystrophy. Accordingly, the mean fasting proinsulin:insulin ratio, expressed as a percentage, was significantly increased in the myotonic patients (20 +/- 5 vs 4 +/- 1%, p < 0.01). The overall C-peptide response to the oral glucose challenge was significantly greater in the myotonic patients compared with the healthy control subjects (p < 0.001). These results provide corroborative evidence of increased beta-cell secretion in myotonic dystrophy.(ABSTRACT TRUNCATED AT 250 WORDS)

C-Peptide↗
PubMed1992

The relation of fetal growth to plasma glucose in young men.

In a study of men aged 59 to 70 years plasma glucose levels 30 min and 2 h after a 75-g glucose load were inversely related to birthweight. To determine whether there are similar relations at a younger age the 30-min plasma glucose levels of 40 men aged 21 years, who were born in one hospital in the United Kingdom, were measured. Lower birthweight was associated with higher 30-min plasma glucose levels. This trend was independent of gestational age, and current body mass, height and social class.

Birth Weight↗
PubMed1992

Immunoradiometric assay of insulin, intact proinsulin and 32-33 split proinsulin and radioimmunoassay of insulin in diet-treated type 2 (non-insulin-dependent) diabetic subjects.

Plasma insulin, intact proinsulin and 32-33 split proinsulin measured by specific immunoradiometric assays and insulin and C-peptide measured by radioimmunoassay were measured during a constant infusion of glucose test in ten diet-treated subjects with a history of Type 2 (non-insulin-dependent) diabetes (termed diabetic subjects), mean fasting plasma glucose 6.0 +/- 1.0 mmol/l (mean +/- SD), and 12 non-diabetic control subjects. Immunoreactive insulin concentrations measured by radioimmunoassay were 33% higher than insulin and 16% higher than the sum of insulin and its precursors by immunoradiometric assay. The diabetic and non-diabetic subjects had similar fasting concentrations of insulin, intact proinsulin and 32-33 split proinsulin. The ratio of fasting intact proinsulin to total insulin was greater in the diabetic than the non-diabetic group 12.0% (6.8-21.0%, 1 SD range) and 6.3% (4.0-9.8%), respectively, p less than 0.01), though the groups overlapped substantially. After glucose infusion, diabetic and non-diabetic subjects had similar intact proinsulin concentrations (geometric mean 4.9 and 5.2 pmol/l, respectively), but the diabetic group had impaired insulin secretion by immunoradiometric assay (geometric means 55 and 101 pmol/l, p less than 0.05) or by radioimmunoassay C-peptide (geometric means 935 and 1410 pmol/l, p less than 0.05), though not by radioimmunoassay insulin (87 and 144 pmol/l, p = 0.12), respectively. Individual immunoradiometric assay insulin responses to glucose expressed in terms of obesity were subnormal in nine of ten diabetic subjects. Radioimmunoassay insulin and C-peptide gave less complete discrimination (subnormal responses in six of ten and eight of ten, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Glucose↗
PubMed1992

Sensitive amplified immunoenzymometric assays (IEMA) for human insulin and intact proinsulin.

Immunoenzymometric assays (IEMAs) for human insulin and intact proinsulin were developed using the amplification system developed by Johannsson et al. (Clin. Chim. Acta 148 (1985) 119-124) for the detection of the enzyme alkaline phosphatase. The detection limit of the assays was 0.8 pmol/l for proinsulin and 0.8 pmol/l for insulin whereas it was 1.8 pmol/l and 2.3 pmol/l respectively for the homologous immunoradiometric assays (IRMA). These assays are superior to immunoradiometric assays in terms of sensitivity, shelf-life of the labelled antibody and suitability for automation.

Alkaline Phosphatase↗
PubMed1991

Fetal and infant growth and impaired glucose tolerance at age 64.

OBJECTIVE: To discover whether reduced fetal and infant growth is associated with non-insulin dependent diabetes and impaired glucose tolerance in adult life. DESIGN: Follow up study of men born during 1920-30 whose birth weights and weights at 1 year were known. SETTING: Hertfordshire, England. SUBJECTS: 468 men born in east Hertfordshire and still living there. MAIN OUTCOME MEASURES: Fasting plasma glucose, insulin, proinsulin, and 32-33 split pro-insulin concentrations and plasma glucose and insulin concentrations 30 and 120 minutes after a 75 g glucose drink. RESULTS: 93 men had impaired glucose tolerance or hitherto undiagnosed diabetes. They had had a lower mean birth weight and a lower weight at 1 year. The proportion of men with impaired glucose tolerance fell progressively from 26% (6/23) among those who had weighted 18 lb (8.16 kg) or less at 1 year to 13% (3/24) among those who had weighed 27 lb (12.25 kg) or more. Corresponding figures for diabetes were 17% (4/23) and nil (0/24). Plasma glucose concentrations at 30 and 120 minutes fell with increasing birth weight and weight at 1 year. Plasma 32-33 split proinsulin concentration fell with increasing weight at 1 year. All these trends were significant and independent of current body mass. Blood pressure was inversely related to birth weight and strongly related to plasma glucose and 32-33 split proinsulin concentrations. CONCLUSIONS: Reduced growth in early life is strongly linked with impaired glucose tolerance and non-insulin dependent diabetes. Reduced early growth is also related to a raised plasma concentration of 32-33 split proinsulin, which is interpreted as a sign of beta cell dysfunction. Reduced intrauterine growth is linked with high blood pressure, which may explain the association between hypertension and impaired glucose tolerance.

Aged↗
PubMed1991

Height and glucose tolerance in adult subjects.

In a prospective study concerning the pathogenesis of impaired glucose tolerance and Type 2 (non-insulin-dependent) diabetes mellitus, 346 subjects with no clinical history of diabetes were given a standard 75 g oral glucose tolerance test. The expected positive associations between 120-min plasma glucose concentration and age and body mass index were observed in both sexes and between 120-min plasma glucose and waist/hip ratio in male subjects. An unexpected negative correlation was found between 120-min plasma glucose and height in both sexes (r = -0.23, (95% confidence interval, -0.38 - -0.07) p less than 0.007 for male subjects and r = -0.24, (-0.37 - -0.11) p less than 0.006 for female subjects). These negative associations with height remained significant after controlling for age and body mass index in male subjects but not in female subjects. In the latter a highly significant negative relationship of height with age was recorded (r = -0.33, (-0.45 - -0.20) p less than 0.0001). Comparison between individuals with impaired glucose tolerance and control subjects matched for sex, age and body mass index showed that subjects with impaired glucose tolerance are significantly shorter. Mean (+/- SEM) height in the male subjects with impaired glucose tolerance (n = 29) was 173.4 +/- 1.1 cm vs 176.9 +/- 1.3 cm in control subjects, p = 0.02. In the female subjects (n = 39) mean (+/- SEM) height was 159.4 +/- 1.0 cm vs 162.4 +/- 1.0 cm in control subjects, p = 0.02. The negative relationship between height and glucose tolerance is a new epidemiological observation which has not been previously reported.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

The relationships of concentrations of insulin, intact proinsulin and 32-33 split proinsulin with cardiovascular risk factors in type 2 (non-insulin-dependent) diabetic subjects.

Standard radioimmunoassay for insulin may substantially overestimate levels of insulin because of cross-reaction with other insulin-like molecules. We have measured concentrations of insulin, intact proinsulin and 32-33 split proinsulin using two-site monoclonal antibody based immunoradiometric assays, and of insulin by a standard radioimmunoassay ("immunoreactive insulin") in 51 Type 2 (non-insulin-dependent) diabetic subjects in the fasting state. The relationships of these concentrations were sought with those of total cholesterol, high density lipoprotein cholesterol, low density lipoprotein cholesterol, triglyceride, plasminogen activator inhibitor, blood pressure, and indices of body fat distribution. Significant relationships were apparent between concentrations of "immunoreactive insulin" as measured by standard radioimmunoassay and triglyceride (rs = 0.42, p less than 0.001), total cholesterol (rs = 0.25, p = 0.038), high density lipoprotein cholesterol (rs = -0.30, p = 0.018) and body mass index (rs = 0.30, p = 0.017), but only the relationships with triglyceride (rs = 0.36, p = 0.006) and body mass index (rs = 0.26, p = 0.34) remained significant when concentrations of immunoradiometrically measured insulin were employed. Concentrations of 32-33 split proinsulin, which comprises the major insulin-like molecule in these subjects, correlated positively with triglyceride (rs = 0.33, p = 0.009), total cholesterol (rs = 0.23, p = 0.050), and plasminogen activator inhibitor (rs = 0.26, p = 0.049), and negatively with high density lipoprotein cholesterol (rs = -0.29, p = 0.021).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Radioimmunoassay may overestimate insulin in non-insulin-dependent diabetics.

We have compared insulin concentrations measured by radioimmunoassay (RIA) in plasma from 50 fasting non-insulin-dependent diabetics (NIDDM) with those measured by a new monoclonal antibody-based two-site immunoradiometric assay (IRMA) of insulin (which has no significant cross-reaction with proinsulin-like molecules). We find that the RIA measures the sum of the insulin and proinsulin like molecules and that the IRMA insulin concentrations are 38% of those measured by the RIA in those diabetic subjects. We conclude that the importance of insulin deficiency in NIDDM may have been obscured by this error.

Adult↗
PubMed1989

Sensitive and specific two-site immunoradiometric assays for human insulin, proinsulin, 65-66 split and 32-33 split proinsulins.

Monoclonal antibody-based two-site immunoradiometric assays are described for human insulin, proinsulin, 65-66 split and 32-33 split proinsulin. The detection limits of the assays lie in the range 0.8-2.5 pM. The assays for 65-66 and 32-33 split proinsulins do not distinguish between these substances and their respective C-terminal di-desamino derivatives. The assay of 65-66 split proinsulin does not cross-react with insulin, proinsulin or 32-33 split proinsulin. This material was undetectable (less than 1.0 pM) in plasma taken after an overnight fast in eight normal male subjects and the maximum individual concentration reached in plasma taken during an oral glucose tolerance test of these subjects was 3.8 pM. The proinsulin assay cross-reacted 66% with 65-66 split proinsulin but not with insulin or 32-33 split proinsulin. The 32-33 split proinsulin assay cross-reacted 84 and 60% with proinsulin and 65-66 split proinsulin respectively. The insulin assay cross-reacted 5.3, 62 and 5.0% with intact proinsulin, 65-66 split proinsulin and 32-33 split proinsulin respectively. The very low concentration of 65-66 split proinsulin meant that this derivative did not interfere significantly with the specificity of the assays of proinsulin and insulin. The concentration of 32-33 split proinsulin could be calculated by subtracting the cross-reactivity of the measured proinsulin. The mean concentrations of insulin, proinsulin and 32-33 split proinsulin in eight young male subjects in the fasting state were (pM +/- S.E.M.) 20 +/- 0.3, 2.3 +/- 0.3 and 2.1 +/- 0.7 and at the maximum reached during an oral glucose tolerance test, 150 +/- 26, 9.9 +/- 1.4 and 19.7 +/- 6.0 respectively.

Adult↗
PubMed1989

Abnormalities of thyrotrophin (TSH) evening rise and pulsatile release in haemodialysis patients: evidence for hypothalamic-pituitary changes in chronic renal failure.

Using a sensitive enzyme amplified immunoassay for TSH, the evening rise and pulsatile release of TSH were studied in 10 men with chronic renal failure treated by haemodialysis. Compared to euthyroid male controls the evening rise of TSH was attenuated (median 0.066 vs 0.195 mU/l/h, P less than 0.01) and the rate of rise correlated with the TSH response to TRH (r = 0.93, P less than 0.001). All subjects showed TSH pulsatility in at least one method of data analysis but the less sensitive incremental method showed no significant difference in pulse frequency and amplitude between the two groups. However, with time series analysis, periodicity was shorter (median 45 vs 95 min, P = 0.013) and pulse amplitude smaller (median 0.06 vs 0.175 mU/l, P = 0.017) in renal patients. Pulse amplitude, but not periodicity, correlated with the TSH response to TRH (r = 0.68, P less than 0.05). In addition, serum total thyroxine, free thyroxine and free triiodothyronine concentrations were reduced, while serum prolactin and 17 beta-oestradiol concentrations were raised. These changes in TSH evening surge and pulsatile release may contribute to the reduction in thyroidal hormone concentrations seen in renal failure and emphasize the value of sensitive methods of hormone and pulse data analysis.

Adult↗
PubMed1989

Neonatal renal function assessment.

Urine samples from neonates admitted to a special care baby unit were analysed to establish ranges for urinary retinol binding protein, albumin, and total protein concentrations in healthy term and preterm infants and to investigate changes seen in disease states. Urinary excretion of retinol binding protein was greater in preterm infants and was increased in sick infants. This was greater than would be predicted from changes in creatinine excretion with gestational or postconceptional age. Urinary retinol binding protein appeared more sensitive to illness than did urinary albumin or total protein.

Albuminuria↗
PubMed1989

The effect of a 72-h fast on plasma levels of pituitary, adrenal, thyroid, pancreatic and gastrointestinal hormones in healthy men and women.

Seventeen human subjects fasted without electrolyte replacement for 3 days and hormone levels were measured before, during and after the fast. Immediate consequences of the fasting state in healthy human subjects include a marked increase in plasma cortisol. ACTH, beta-endorphin, beta-lipotrophic hormone, adrenaline, noradrenaline and dopamine. Levels of all these hormones were much greater on the first morning of the fast than in the post-prandial state, even though the plasma glucose level was no lower than that observed on the morning before the fast began. A clear fall in TSH and tri-iodothyronine (T3) levels was observed, but thyroxine levels did not change significantly. Insulin levels fell whereas proinsulin levels did not fall during the fast, though they did rise markedly upon re-feeding. An increase in GH levels was particularly apparent in male subjects, but was also seen in females when evening samples were compared. Pancreatic glucagon showed a modest rise during the fast, but fell again on refeeding; total glucagon also rose as the fast proceeded, but increased markedly upon re-feeding. Levels of gastrin and peptide YY remained low during the fast. Plasma electrolyte levels were unchanged. The following were closely correlated: cortisol with ACTH, T3 with log10 TSH, dopamine with noradrenaline, and (negatively, during the fast) pancreatic glucagon with glucose.

Adrenal Cortex Hormones↗
PubMed1989

Cognitive style as related to emotional empathy.

This study examined relationships among two measures of FDI (the hidden figure test (HFT) and the portable rod and frame test (PRFT) and a measure of interpersonal sensitivity (the questionnaire measure of emotional empathy (QMEE] in a group of dental hygiene students. All measures were administered to 44 dental hygiene students and 42 students enrolled in an introductory psychology course. While the dental hygiene students were more field independent than a previously reported normative sample (t = 24.6 p less than 0.002), they were not characteristically different than a representative group of college students on any of the measures. For students enrolled in the psychology course, but not the dental hygiene students, the more field independent students were, the less empathic they appeared to be. These results do not entirely support previous research indicating that dental hygiene students typically are more field independent.

Adolescent↗