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Biomedical subjects

J Jones

Publications and source records attributed to J Jones.

At least 433 records · Page 24Linked to original sources
PubMed1994

Menstrual irregularities are more common in adolescents with type 1 diabetes: association with poor glycaemic control and weight gain.

Ovarian function in post-menarchal girls with Type 1 diabetes was evaluated. Menstrual histories from 24 adolescents with Type 1 diabetes were compared with those from 24 age and sex matched controls. A fasting blood sample was obtained from subjects with Type 1 diabetes for the measurement of ovarian and adrenal sex hormones, LH and FSH, glucose and insulin, insulin-like growth factor-I (IGF-I), and insulin-like growth factor binding protein-1 (IGFBP-1); and an ovarian ultrasound scan was performed. Menstrual irregularity was more prevalent in patients with Type 1 diabetes than controls (54% vs 21%, p < 0.01) and their mean body mass index (BMI) was greater (22.3 +/- 0.5 (+/- SEM) vs 20.7 +/- 0.6 kg m-2, p < 0.05). Subjects with Type 1 diabetes with irregular menses (when compared with diabetic subjects with a regular cycle) had a significantly higher HbA1 (12.8 +/- 0.4 vs 10.5 +/- 0.5%, p < 0.01) and BMI (23.2 +/- 0.6 vs 21.4 +/- 0.6 kg m-2, p < 0.05) associated with a lower sex hormone binding globulin (SHBG) (37.2 +/- 4.0 vs 52.6 +/- 4.0 nmol l-1, p < 0.025) and IGF-I (1.4 +/- 0.2 vs 2.2 +/- 0.2 mUI-1, p < 0.025) and a higher LH:FSH ratio (2.6 +/- 0.5 vs 1.4 +/- 0.2, p < 0.05). Polycystic ovarian changes were identified in 10/13 (77%) of these patients with an irregular cycle. Menstrual irregularity is common in post-menarchal girls with Type 1 diabetes and is associated with poor glycaemic control and weight gain. The apparent high incidence of polycystic ovarian change requires further investigation.

Adolescent↗
PubMed1994

Alterations in growth hormone secretion and clearance in peripubertal boys with chronic renal failure and after renal transplantation. Cooperative Study Group of Pubertal development in Chronic Renal Failure.

To elucidate the endocrine mechanisms underlying the pubertal growth failure observed in patients with chronic renal failure (CRF), we used deconvolution analysis to estimate the rates of GH secretion and elimination in nighttime plasma GH profiles of peripubertal boys with CRF and after renal transplantation (Tx). Forty-three boys with advanced CRF (conservative treatment with glomerular filtration rate < 25 mL/min.1.73 m2 or dialysis; CT/D group), 38 boys after Tx, and 40 healthy control boys were studied. The estimated plasma GH half-life (mean +/- SEM) was significantly higher (P < 0.05) in CRF (25 +/- 1.8 min) than in Tx patients (21 +/- 1.6 min) and controls (20 +/- 0.5 min). In the pre- and early pubertal CT/D boys, the calculated GH secretion rate was low normal or reduced when expressed in absolute numbers or normalized per unit distribution volume or body surface. In late puberty, whereas body surface-corrected GH secretion was double the prepubertal value in normal boys (389 +/- 56 vs. 868 +/- 113 micrograms/m2.11 h; P < 0.01), it did not differ significantly from the prepubertal rate in CT/D boys (281 +/- 59 vs. 389 +/- 56 micrograms/m2.11 h). GH hyposecretion resulted from a decrease in the mass of GH released within each burst, whereas burst frequency was unchanged. In the Tx group, GH secretion rates were significantly reduced in the prepubertal (221 +/- 39 micrograms/m2.11 h; P < 0.05) and late pubertal period (266 +/- 64 micrograms/m2.11 h; P < 0.01). The mass of hormone secreted per burst was significantly reduced at each pubertal stage, whereas GH secretory burst frequency tended to be increased (significant in prepubertal group, P < 0.05). The GH secretion rate was positively correlated with plasma testosterone levels (r = 0.58; P < 0.0001) in controls, but not in CT/D or Tx patients. GH secretion rates were lower than expected at each level of plasma testosterone in both patient groups except CT/D boys with plasma testosterone below 0.9 nmol/L. In the Tx group, GH secretion rate was positively correlated with relative height (r = 0.31; P < 0.05). The dosage of corticosteroids administered for immunosuppression was negatively correlated with GH burst mass (r = -0.42; P < 0.01) and GH secretion rate (r = -0.29; P = 0.08) and positively correlated with GH burst frequency (r = 0.49; P < 0.01). We conclude that in peripubertal boys with CRF, a state of GH hyposecretion is associated with an increase in the apparent plasma half-life of GH.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1994

Reversible effects of cessation and recommencement of thyroxine treatment on insulin-like growth factors (IGFs) and IGF-binding proteins in patients with total thyroidectomy.

There is a complex relationship between the thyroid and pituitary GH/insulin-like growth factor (IGF) axes. IGFs circulate in association with six specific high affinity binding proteins (IGFBPs) that modulate their bioactivity and bioavailability. Recent evidence suggests that gene expression and circulating levels of IGFBPs are related to prevailing thyroid hormone status. We have investigated the effects of both withdrawal and reinstitution of thyroid hormone replacement on circulating IGF and IGFBP levels in athyreotic patients (n = 10). The mean IGF-I concentration fell from a basal level of 191.8 +/- 12 micrograms/L to a nadir of 136.4 +/- 17.8 micrograms/L (P = 0.026) 5 weeks after stopping T4 treatment and returned to normal values 3 weeks after recommencement of replacement treatment. The fall in IGF-II levels followed a similar pattern from a basal mean level of 649 +/- 33.7 to 547 +/- 42.7 micrograms/L (P = 0.026) at 5 weeks. These changes paralleled the fall in free T3 and free T4. Similarly, IGFBP-1 levels fell after stopping T4 treatment from a basal level of 54.8 +/- 4.0 to 24.6 +/- 7.0 micrograms/L (P = 0.001) 5 weeks later. After T4 treatment was restarted, IGFBP-1 levels rose and were not significantly different from basal values by week 8. There were strong positive correlations between paired data sets for IGFBP-1 and free T3 (r = 0.488; P = 0/0037) and free T4 (r = 0.56; P = 0.0006), and a strong negative correlation with TSH (r = -0.515; P = 0.0001). Insulin is known to be important in the regulation of IGFBP-1, but no changes in fasting insulin levels during T4 withdrawal were noted, and levels of IGFBP-1 did not exhibit the normal inverse relationship with circulating insulin levels. Levels of IGFBP-2, assessed by Western ligand blotting, increased during the development of hypothyroidism, peaked 5 weeks after stopping T4 replacement, and declined on reinstitution of replacement treatment. A further level of regulation of the IGF-IGFBP axis is afforded by the presence of specific circulating IGFBP proteases. Proteases directed against IGFBP-3 proteolytically cleave the major carrier BP in the circulation and reduce its binding affinity, possibly resulting in increased tissue IGF bioavailability. Despite the marked reduction in circulating IGF levels and the generation of significant biochemical hypothyroidism, IGFBP-3 protease activity was not apparent during the 10-week period of the study.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1994

Valproate-mediated disturbances of hemostasis: relationship to dose and plasma concentration.

Valproic acid (VPA) may cause impaired platelet function, thrombocytopenia and, occasionally, severe bleeding. Controversy exists both as to the mechanism of this alteration in hemostasis and as to whether these adverse effects are either dose-related or idiosyncratic. Previous investigations have focused primarily on pediatric patients who commonly were receiving multiple anticonvulsant medications. We evaluated a cohort of 27 adult patients with epilepsy who were receiving VPA monotherapy and compared them with age-matched controls to determine whether a correlation exists between platelet count, function, bleeding time, levels of von Willebrand's factor antigen, and VPA dose or plasma concentration. VPA patients had significantly lower platelet counts and longer bleeding times than did controls (p < 0.05). Platelet count was inversely correlated to VPA dose and both free and total VPA concentration (p < 0.01). There was no significant difference in levels of von Willebrand's factor antigen between patients and controls. We assessed platelet aggregation by measurement of whole-blood platelet aggregation and release with agonists including adenosine diphosphate, thrombin, collagen, arachidonic acid, and ristocetin. VPA patients had significant decreases in platelet aggregation values compared with controls. There were significant differences in collagen, arachidonic acid, and adenosine diphosphate release and aggregation between groups that correlated to both VPA dose (p < 0.01) and concentration (p < 0.05). Prolongation of bleeding time was significantly correlated to both VPA dose and concentration. Our data suggest a significant relationship between impaired platelet function and both VPA dose and plasma concentration.

Adult↗
PubMed1994

ARCHITECTURE AND COMPOSITION OF THE MUSCLES THAT DRIVE STOMATOPOD EYE MOVEMENTS

1. The peculiar structure of the stomatopod eye requires it to make complicated movements. These include slow 'scans', which relate to the animal's colour vision system, as well as faster 'saccades'. 2. The myology of the eyecup is investigated and shown to consist of eight individual muscles which are divided, on kinematic grounds, into six functional groups. 3. These groups form three pairs of dominant prime movers, with each having primary control over one of the eye movement axes (longitude, latitude and bearing). This is important as it allows each rotational axis to move independently of the other two. 4. Histochemical typing reveals at least four distinct classes of fibre within each muscle. 5. The relationship between the number of types of fibre and classes of eye movement is discussed, as are the implications of coordinate prime movers for neuromuscular control.

Journal Article↗
PubMed1994

Embodied meaning: menopause and the change of life.

A culture's conception of gendered bodies is determined more by social constructions than by the nature of reality, and as such, reflects a specific historical, social, and political context. Constructions of women's bodies have changed throughout history but since the Enlightenment and, with it, the hegemony of science, they have been determined primarily by a biomedical perspective. This perspective results in a master medical narrative which reduced women's bodies, in general, to a biomedical reality; and their experience of menopause, specifically, to a biological event representing deterioration and decline. Analyzing the meaning that a research cohort of women make of their experience of menopause, I examine the ways in which their meaning conforms to and/or resists the medical narrative, as well as the new narratives which are created as alternatives. Implications for social workers in health care are addressed.

Adaptation, Psychological↗
PubMed1994

Response of insulin-like growth factor (IGF)-binding protein-1 (IGFBP-1) and IGFBP-3 to IGF-I treatment in severe insulin resistance.

It has been suggested that recombinant human IGF-I (rhIGF-I) is a potential therapeutic agent in diabetes mellitus. It is known to have glucose-lowering effects in normal individuals, in patients with non-insulin-dependent diabetes (NIDDM) and in extreme insulin-resistant states. IGF-binding proteins (IGFBPs) have the potential to affect the biological activity of rhIGF-I. We have studied the effect of infused rhIGF-I on IGFBP-1 and IGFBP-3 in a patient with Mendenhall's syndrome, a rare insulin-resistant state. During an infusion of 20 mg rhIGF-I, glucose concentrations fell from 44.1 +/- 7.2 to 31.5 +/- 7.2 (S.E.M.) mmol/l (P = 0.001), and insulin and C-peptide levels fell from 920 +/- 62 to 542 +/- 45 mU/l (P = 0.008) and 5466 +/- 633 to 3071 +/- 297 pmol/l (P = 0.02) respectively. Significant lowering of phosphate, magnesium and alkaline phosphatase concentrations was also noted. IGF-I levels rose from 48 +/- 10.2 to 410 +/- 50.1 micrograms/l (P = 0.001), and those of IGF-II fell from 279.8 +/- 8.3 to 104.3 +/- 7.9 micrograms/l (P = 0.001). IGFBP-1 concentrations did not significantly change during the infusion but those of IGFBP-3 increased from 1655 +/- 127 to 2197 +/- 334 micrograms/l (P = 0.002), despite a significant fall in GH concentrations from 10.7 +/- 2.6 to 4.1 +/- 1.1 mU/l (P = 0.007), suggesting that IGFBP-3 regulation is also IGF-I-dependent.(ABSTRACT TRUNCATED AT 250 WORDS)

Acanthosis Nigricans↗
PubMed1994

Using CD4 counts to evaluate the stages and epidemiology of HIV infection in South Carolina public clinic patients.

OBJECTIVES: CD4 lymphocyte counts decrease with the duration of human immunodeficiency virus (HIV) infection. We used CD4 counts collected for clinical reasons to evaluate the stage of HIV infection and the epidemiology of recent HIV infections among attendees of South Carolina's public health clinics. METHODS: We measured the CD4 T-lymphocyte counts of persons newly diagnosed with HIV infection April 1989 through June 1990 at South Carolina public health clinics who returned for follow-up. RESULTS: Of 812 newly diagnosed HIV-infected health department patients, 420 (52%) had their CD4 lymphocyte counts measured. Of these 420, 51 (12%) had CD4 counts of < 200, the level below which prophylaxis for pneumocystis pneumonia prolongs survival, and 193 (46%) had CD4 counts of < 500, the level below which zidovudine may prolong disease-free survival. The highest CD4 counts (> or = 900), which are associated with more recent HIV infection, were more common in females. CONCLUSIONS: In South Carolina, almost half of newly reported HIV-infected persons who agreed to CD4 testing at the health department might benefit from immediate drug therapy. Within this population, women may be an emerging risk group that requires specifically directed HIV prevention efforts.

Adolescent↗
PubMed1994

Comparative susceptibility of peripheral blood leucocytes and related cell lines to killing by T-cell perforin.

The comparative susceptibility of lymphocyte subsets, monocytes and polymorphonuclear leucocytes (PMN) to killing by murine perforin was measured using physical separation techniques, cell-surface phenotyping and scatter characteristics to isolate cell types, together with propidium iodide (PI) uptake as a measure of cell death. In the majority of individuals, PMN were more resistant to perforin than other peripheral blood cells including natural killer (NK) cells and CD8+ lymphocytes. Among the lymphocytes, CD4+ cells were the most susceptible subset, followed by CD19+, CD8+ and CD56+ lymphocytes respectively. The human promyelocytic leukaemia cell line, HL-60, and the human histiocytic lymphoma cell line, U937, were readily killed by perforin. When HL-60 were differentiated to either macrophage- or neutrophil-like end cells, and U937 differentiated to macrophage-like end cells, there was no difference between differentiated and undifferentiated cells in their relative susceptibility to perforin. The relative resistance of PMN to perforin may be important in protecting them from damage in in vivo situations where both NK cells and neutrophils are localized in the same inflammatory areas.

Animals↗
PubMed1994

A nosocomial outbreak of Mycobacterium tuberculosis.

BACKGROUND: The national incidence of tuberculosis (TB) is increasing, and hospitals are a site of transmission. We investigated a nosocomial outbreak of TB at a 160-bed community hospital in South Carolina that highlights the central role that primary care physicians must play to control this epidemic. METHODS: We reviewed medical records to identify potential source cases. We retrospectively evaluated exposures to suspected source patients and the subsequent tuberculin reactivity of the 38 hospital employees who had a previous negative tuberculin skin test and were assigned to the ward where the outbreak began. We also evaluated the out-of-hospital contacts of TB cases. RESULTS: A review of medical records identified one patient who had died of prostate cancer and chronic cavitary pneumonia but was never in isolation nor evaluated for TB. Ward employees who worked while this patient was hospitalized had an increased risk for skin-test conversion (43% [12 of 28] vs 0% [0 of 9]; relative risk undefined; P = .02). Among employees who worked with this patient, skin-test converters worked more shifts with (median, 10.5 vs 7), dispensed more medication to (median 7 doses vs 1), and wrote more notes on (median 18 vs 5) the index patient than did nonconverters. Five of 12 of the patient's close out-of-hospital contacts had newly recognized positive tuberculin skin tests. Among 20 casual contacts, there were no new skin-test conversions. CONCLUSIONS: A high index of suspicion, prompt isolation and diagnostic testing of potentially infectious hospitalized patients, and a thorough investigation of contacts of patients with TB are needed to prevent TB transmission.

Aged↗
PubMed1993

Demographic variables in Auckland medical students.

AIMS: To review the important background details of students admitted to the Auckland School of Medicine over its 25 years. METHODS: Data collected at the time of application on 2448 students who successfully gained entry to the course has been analysed and compared with similar demographic variables in the New Zealand population as a whole, and with some of the findings from a survey performed on the total student population enrolling at Auckland University during 1990. RESULTS: Successful applicants had a mean age of 18.6 years, 39.7% were females and 77% were born in New Zealand. Eighty-three percent were European, 3.6% Maori, 2.4% Pacific Islanders and 10.8% Chinese, Indian or other Asian. Sixty-three percent came from cities over 100,000, 16% being from towns less than 20,000 people. State schools were attended by 77% of entrants and 55% went to single sex schools. University students enrolling in 1990 came from affluent backgrounds with 70% of medical students that year being from socioeconomic levels one and two. Parental occupation was found to clearly influence the career choice of students. CONCLUSIONS: Auckland medical students are predominantly from large cities and affluent backgrounds with only those of European origin being admitted in the same proportion as they occupy in the New Zealand population. The high ratio of Asian students reflects their commitment to senior secondary school studies while the lower admission rate for Maori and Polynesian students is due in part to the large number who leave school without completing their secondary education. The possible impact of these demographic variables on recruitment and loss from the course and on the choice and location of practice is discussed.

Adolescent↗
PubMed1993

Coronary artery surgery: are women discriminated against?

OBJECTIVE: To determine whether the sex differences in access to cardiac surgery observed in the United States exist in the United Kingdom. DESIGN: Retrospective analysis of routinely collected data. SETTING: South West Thames and North West Thames regional health authorities. SUBJECTS: 8564 patients discharged from hospital with a principal diagnosis of coronary heart disease in 1987-8 in South West Thames region and 15243 discharges in North West Thames region in 1990-1. MAIN OUTCOME MEASURES: Performance of angiography or coronary artery bypass surgery. RESULTS: In all age groups and among patients with a principal diagnosis of either angina or chronic ischaemia men were significantly more likely than women to undergo revascularisation in both regions. Using multiple logistic regression to control for potential clinical and demographic confounders, the male to female odds ratio for revascularisation among all cases was 1.59 (95% confidence interval 1.25 to 2.03) in South West Thames region and 1.47 (1.32 to 1.63) in North West Thames region. CONCLUSION: There appears to be a systematic difference in the treatment received by men and women in the United Kingdom. The reasons for this are uncertain.

Adult↗
PubMed1993

Screen detected high blood pressure under 40: a general practice population followed up for 21 years.

OBJECTIVE: To assess hypertension detected under 40 in a general practice population. DESIGN: Prospective case-control study. SETTING AND SUBJECTS: Former coal mining community in south Wales. Systematic case finding for hypertension and associated risk factors applied to a mean total population of 1945 from age 20 on a five year cycle through 21 years. Mean population aged 20-39, 227 men and 213 women. Case criteria: age < 40 and mean systolic pressure > or = 160 mm Hg or diastolic pressure > or = 100 mm Hg. Age and sex matched controls randomly sampled from the same population. MAIN OUTCOME MEASURES: Mean initial pressures and pressures at follow up in 1989 or preceding death, and all cardiovascular events. RESULTS: 25 men and 16 women met criteria. Estimated five yearly inceptions were 26/1000 for men and 18/1000 for women. Male group mean initial blood pressure was 164/110 mm Hg for cases, falling to 148/89 mm Hg at follow up. Five male cases died at mean age 47.8, compared with two controls at 49.5. Female group mean initial pressure was 172/107 mm Hg for cases, falling to 145/86 mm Hg at follow up. One female case died aged 50, no controls. 10 male cases had non-fatal cardiovascular events at mean age 40.2, compared with two controls at mean age 50.5. Four female cases had non-fatal events at mean age 47.2, compared with one control aged 58. Male differences were statistically significant. CONCLUSIONS: Hypertension under 40 is dangerous, commoner in men than women, rarely secondary to classic causes, and may be controlled in general practice on a whole community basis.

Adult↗
PubMed1993

Integrin expression in normal, hyperplastic, dysplastic, and malignant oral epithelium.

We have examined the distribution of a range of integrin subunits in normal and lesional oral mucosa. The alpha 2, alpha 3, alpha 6, beta 1, and beta 4 subunits were highly expressed in normal epithelium, and there was weaker, more variable expression of alpha 5 and alpha v. Expression of all subunits was highest in the basal layer of normal epithelium, but extensive staining above the basal layer was also observed, particularly in the floor of the mouth and the lateral margin of the tongue. In dysplastic lesions and hyperplastic epithelium adjacent to ulcers, suprabasal staining was even more pronounced. Staining patterns in squamous cell carcinomas showed considerable variation, both within and between individual tumours: in some areas there was staining reminiscent of normal epithelium, but uniform staining throughout tumour islands, and patchy and variable cytoplasmic and pericellular staining were also seen. Thirteen out of 17 carcinomas showed some loss of integrin expression: six out of ten moderately well differentiated tumours and all the poorly differentiated tumours. Focal loss of alpha 6 and beta 4 was most commonly observed, but loss of alpha 2 and alpha 3 also occurred. Since integrins regulate not only keratinocyte adhesion, but also the initiation of terminal differentiation, the changes in integrin expression that we have observed may have significance for the behaviour of individual tumours.

Carcinoma, Squamous Cell↗