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Biomedical subjects

A J Drake

Publications and source records attributed to A J Drake.

At least 19 recordsLinked to original sources
PubMed2004

The intergenerational effects of fetal programming: non-genomic mechanisms for the inheritance of low birth weight and cardiovascular risk.

Many epidemiological studies in diverse populations have demonstrated a link between low birth weight and subsequent disease. This evidence has given rise to the fetal origins hypothesis, which suggests that exposure of the fetus to an adverse environment in utero leads to permanent programming of tIssue function and a risk of cardiovascular disease. An alternative hypothesis is that low birth weight and adult cardiovascular disease are independent features of a genetic predisposition to cardiovascular disease. This review describes evidence that the programming phenomenon may not be limited to the first generation offspring. Results of human and animal studies identify intergenerational programmed effects on both birth weight and cardiovascular disease. This may represent a mechanism for the non-genetic inheritance of a predisposition to low birth weight and adverse cardiovascular risk across a number of generations.

Adaptation, Physiological↗
PubMed2002

Type 2 diabetes in obese white children.

We report four white adolescents aged 13 to 15 years (three females, one male) from the south and west region of England who presented with type 2 diabetes mellitus associated with significant obesity (body mass index more than +3SDS) in the past two years. Although these are the first reported obese, white cases from the UK to present with diabetes, we believe this clinical scenario will become more prevalent given the epidemic of childhood obesity in this country.

Adolescent↗
PubMed2001

Direct detection of a microlens in the Milky Way.

The nature of dark matter remains mysterious, with luminous material accounting for at most approximately 25 per cent of the baryons in the Universe. We accordingly undertook a survey looking for the microlensing of stars in the Large Magellanic Cloud (LMC) to determine the fraction of Galactic dark matter contained in massive compact halo objects (MACHOs). The presence of the dark matter would be revealed by gravitational lensing of the light from an LMC star as the foreground dark matter moves across the line of sight. The duration of the lensing event is the key observable parameter, but gives non-unique solutions when attempting to estimate the mass, distance and transverse velocity of the lens. The survey results to date indicate that between 8 and 50 per cent of the baryonic mass of the Galactic halo is in the form of MACHOs (ref. 3), but removing the degeneracy by identifying a lensing object would tighten the constraints on the mass in MACHOs. Here we report a direct image of a microlens, revealing it to be a nearby low-mass star in the disk of the Milky Way. This is consistent with the expected frequency of nearby stars acting as lenses, and demonstrates a direct determination of a lens mass from a microlensing event. Complete solutions such as this for halo microlensing events will probe directly the nature of the MACHOs.

Journal Article↗
PubMed2001

Pancreatic dysfunction in severe obesity.

AIMS: To investigate pancreatic function in children attending an obesity clinic. METHODS: Thirty six children (of which 34 were white) with severe obesity of prepubertal onset (body mass index more than +2 SDS) were reviewed clinically and dysmorphologically, with assessment of pancreatic function. RESULTS: Eight had dysmorphic features and 13 had learning difficulties. Four of 17 prepubertal children had hyperinsulinaemia and seven had hyperproinsulinaemia. All 19 pubertal children had hyperinsulinaemia, 14 had hyperproinsulinaemia, and one had type II diabetes. CONCLUSIONS: Metabolic abnormalities predictive of type II diabetes occur in severely obese white children.

Adolescent↗
PubMed2000

Dual X-ray absorptiometry total body bone mineral content and bone mineral density in 18- to 22-year-old caucasian men.

Eighty-six healthy, young Caucasian 18-year-old men with no known disease or bone injury were recruited to this study at the United States Naval Academy. Change in bone mineral density (BMD) of the hip, lumbar spine, and distal tibia, and total body bone mineral content (TBMC) was measured by dual-energy X-ray absorptiometry (DXA). BMD and TBMC of these men were measured within 2 months (67 +/- 3 days) of entering the Academy, and, at the end of their first, second, and fourth years. Hip BMD was unchanged during the study period (p > 0.05). Lumbar spine BMD increased 3% (p < 0.001) and distal tibia BMD increased 5% (p < 0.001). TBMC showed a 7.5% increase over the study period. In this group of young men, gain in BMD and TBMC is greatest to age 21 years, with minimal further increase after age 21. The significance of this rise in bone mass during early adulthood on risk for osteoporotic fractures in later life or its impact on exercise-related bone injuries is unknown and warrants further examination.

Absorptiometry, Photon↗
PubMed2000

Improved clinical practice but continuing service deficiencies following a regional audit of childhood diabetes mellitus.

AIM: To assess the changes in services for children with diabetes in the south west of England between two region-wide audits performed in 1994 and 1998. METHODS: Questionnaires were sent to consultant paediatricians, specialist diabetes nurses, dietitians, and Local Diabetes Service Advisory Groups. Information was gathered on consultant and nursing caseload, clinic structure, dietetic and psychological services, glycated haemoglobin use, and screening services. RESULTS: In 1994 there were 21 consultant paediatricians caring for children with diabetes, only seven of whom fulfilled the British Paediatric Association definition of a specialist. By 1998 there were 14, 12 of whom fulfilled this definition. In 1994 a significant number of children were being seen in general paediatric clinics; by 1998 all centres stated that children were being seen in designated diabetes clinics. Between the two audits, despite a decrease in the average caseload of specialist diabetes nurses, nursing services in many centres remained deficient, as did dietetic and psychology services. Glycated haemoglobin use increased from 16 of 21 consultants to all consultants. In 1998 there was still patchy paediatric representation on Local Diabetes Service Advisory Groups. CONCLUSIONS: The 1994 audit was followed by a change in clinical practice, in contrast to continuing deficiencies in resources, despite the availability of national recommendations and the widespread distribution of the audit report to those in a position of influence.

Child↗
PubMed2000

Growth hormone hypersecretion in a girl with neurofibromatosis type 1 and an optic nerve glioma: resolution following chemotherapy.

Growth hormone hypersecretion is extremely rare in childhood. We report a girl with neurofibromatosis type 1, an extensive optic nerve glioma and growth hormone hypersecretion. She was treated with chemotherapy to prevent further extension of her sight-threatening tumour. Three years after chemotherapy her growth hormone hypersecretion has resolved although she has gone on to develop precocious puberty.

Age Determination by Skeleton↗
PubMed2000

Anemia: a cause of intolerance to thyroxine sodium.

Usual causes of intolerance to thyroxine sodium include coronary artery disease, advanced age, untreated adrenal insufficiency, and severe hypothyroidism. We describe 4 patients with iron deficiency anemia and primary hypothyroidism. After treatment with thyroxine sodium, these patients developed palpitations and feelings of restlessness, which necessitated discontinuation of the thyroid hormone. After the anemia was treated with ferrous sulfate for 4 to 7 weeks, they were able to tolerate thyroxine sodium therapy. Iron deficiency anemia coexisting with primary hypothyroidism results in a hyperadrenergic state. In such patients, we postulate that thyroid hormone administration causes palpitations, nervousness, and feelings of restlessness. Correction of any existing pronounced anemia in hypothyroid patients who are intolerant to thyroxine sodium therapy may result in tolerance to this agent.

Adult↗
PubMed1996

Pseudocarcinoid syndrome associated with hypogonadism and response to testosterone therapy.

OBJECTIVE: To characterize a disorder of episodes of flushing and increased levels of 5-hydroxyindoleacetic acid (5-HIAA) in men with secondary hypogonadism who respond to testosterone therapy. MATERIAL AND METHODS: We present detailed case reports of three male patients who had flushing, secondary hypogonadism, and increased urinary 5-HIAA levels and describe their clinical and laboratory features before and after treatment with testosterone. In addition, six male patients with hypogonadism (three with primary and three with secondary hypogonadism) without flushing were assessed. RESULTS: The three patients with flushing and secondary hypogonadism (serum total testosterone 5.45 +/- 0.63 nmol/L, free testosterone 89.3 +/- 7.0 pmol/L, follicle-stimulating hormone 3.85 +/- 0.58 IU/L, and luteinizing hormone 4.41 +/- 0.98 IU/L) had increased urinary 5-HIAA levels (98.5 +/- 12.2 micromol/24 h) but normal blood serotonin levels (9.66 +/- 1.58 micromol/L). During a pentagastrin-calcium stimulation test, serum calcitonin and blood serotonin values were normal in patients with secondary hypogonadism and flushing. Detailed investigation showed no evidence of a carcinoid tumor. Urinary 5-HIAA levels became normal (16.6 +/- 1.73 micromol/24 h) after treatment with testosterone. When testosterone therapy was discontinued in two patients, flushing and increased urinary 5-HIAA levels recurred. Furthermore, flushing and the elevated urinary 5-HIAA values resolved when testosterone treatment was reinitiated. The six patients with hypogonadism without flushing had normal urinary 5-HIAA levels (14.9 +/- 3.31 micromol/24 h). CONCLUSION: Male patients with flushing and increased urinary 5-HIAA levels should undergo assessment for hypogonadism after screening for carcinoid tumor. If hypogonadism is diagnosed, resolution of flushing and normalization of 5-HIAA may be achieved with testosterone treatment. We suggest that pseudocarcinoid syndrome associated with hypogonadism be the descriptive label used for this combination of clinical features.

Aged↗
PubMed1996

Pharmacology of the endocrine pancreas, adrenal cortex, and female reproductive organ.

It is estimated that there are up to 14 to 15 million diabetics in the United States and that many are unaware of their condition. Millions of women will become pregnant each year, although many will take oral contraceptives to prevent pregnancy. Thousands of patients are prescribed chronic doses of glucocorticoid medications every year. Many of these patients can be expected to seek some degree of dental care. The dentist must have a basic understanding of the physiologic changes associated with each of these endocrinological conditions to provide safe and appropriate dental care.

Adrenal Cortex Diseases↗
PubMed1995

Nicotinic acid decreases serum thyroid hormone levels while maintaining a euthyroid state.

OBJECTIVE: To evaluate the effects of nicotinic acid on serum thyroid hormone levels in the absence of systemic illness or hepatic dysfunction. DESIGN: We determined the effect of treatment with nicotinic acid on serum thyroid hormone levels in one female and four male patients (mean age, 44.4 years) with hyperlipidemia. MATERIAL AND METHODS: In the five study patients, we measured serum lipids in conjunction with serum thyroxine (T4), triiodothyronine (T3) resin uptake, T3, free T4, thyroid-stimulating hormone (TSH), and thyroxine-binding globulin before, during, and after treatment with nicotinic acid. RESULTS: Serum lipid levels responded appropriately to nicotinic acid treatment. Thyroid function studies done a mean of 1.3 years (range, 0.5 to 3.5) after initiation of nicotinic acid therapy (mean daily dose, 2.6 +/- 0.7 g) revealed significant decreases in serum levels of total T4 (21%), free T4 index (16%), T3 (13%), and thyroxine-binding globulin (23%) (P < 0.02), whereas no significant changes were noted in free T4, T3 resin uptake, and TSH levels. During the course of treatment, the patients, who were carefully questioned, had no symptoms of hypothyroidism. Hypothyroidism was further excluded in three patients who had a normal serum TSH response to administration of thyrotropin-releasing hormone. In two patients, measurements of thyroid function returned to pretreatment levels after discontinuation of nicotinic acid therapy. No patient had significant abnormalities in liver-associated enzymes or evidence of systemic illness during the course of treatment. CONCLUSION: These results suggest that nicotinic acid decreases serum thyroid hormone concentrations while maintaining a euthyroid state. This effect may be mediated through reduction in thyroxine-binding globulin, but other mechanisms may also be involved.

Adult↗
PubMed1982

Is action potential duration of the intact dog heart related to contractility or stimulus rate?

1. The contractility (maximum rate of rise of left ventricular pressure) and action potential duration were measured in intact closed-chest anaesthetized dogs with complete atrioventricular dissociation and beta-adrenergic blockade.2. Measurements were confined to test beats following a 1 sec interval. Prior to the test interval (priming period) a variety of potentiating stimulus trains were introduced.3. When the frequency of stimulation was increased in the priming period (frequency potentiation), there was an inverse relationship between action potential duration and contractility of the test beat.4. When the test beat was potentiated by a single beat terminating the priming period with one short interval (post-extrasystolic potentiation), there was no relationship between the action potential duration and contractility of the test beat.5. Paired pulse stimulation was used for any given frequency to vary contractility by short interval potentiation. For any given frequency of stimulation there was no relationship between action potential duration and contractility of the test beat. For any given value of contractility, action potential duration decreased with increased frequency of stimulation.6. The introduction of a high frequency train caused a step decrease in action potential duration on the first beat of the train. This was followed by a further slow decline in action potential duration with a time course of over 3 min. These two changes could be dissociated by the introduction during the train of one second interval test pulses, which only showed the slow shortening.7. The lack of a consistent relationship between action potential duration and contractility of the test beat disagrees with the hypothesis that repolarization is controlled by the activator calcium responsible for the contractility. The action potential shortening associated with increased frequency is related to the frequency change per se.8. The slow time course of change in action potential duration following an increase in stimulation frequency suggests that these changes are caused by the accumulation of an ion or metabolite, or possibly by changes of activity of the electrogenic Na(+)-K(+) pump.

Action Potentials↗