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Biomedical subjects

P J Boyle

Publications and source records attributed to P J Boyle.

At least 37 records · Page 2Linked to original sources
PubMed1995

Managed care in mental health: the ethical issues.

Praise and blame of managed mental health care are on the rise on many fronts, including allegations that it could adversely affect quality of care, access to care, the physician/patient relationship, and informed patient choice. Given the heterogeneity among managed mental health care organizations--each with differing practices--it is difficult to sift the ethically defensible concerns from the indefensible ones. In this paper we identify and examine the different moral concerns about managed mental health care and mark which problems have been addressed or are in need of resolution. We also identify which problems are unique to managed mental health care.

Adolescent↗
PubMed1995

Spirometry and maximal respiratory pressure references from healthy Minnesota 65- to 85-year-old women and men.

OBJECTIVE: To obtain spirometry and maximal respiratory pressure (MRP) reference values for elderly persons. DESIGN: Survey. SETTING: General community. PARTICIPANTS: Four hundred seventy-one healthy ambulatory white women and men age 65+ years. METHODS: A stringent spirometry quality assurance program exceeded American Thoracic Society recommendations. A "healthy" subgroup of 176 women and 112 men between the ages of 65- and 85 years were identified by excluding those with conditions that negatively influenced FEV1 in a multiple regression analysis. Reference equations and normal ranges for FEV1, FVC, FEF25-75%, peak flow, and maximal inspiratory and expiratory pressures (MRPs) were determined from the healthy group with good quality maneuvers. RESULTS: Less than 10% of the subjects were unable to perform three acceptable spirometry maneuvers and ten MRP maneuvers. When the age and height corrected FEV1s from this group were compared with other spirometry reference studies, mean values from the women were nearly identical to those from Morris, while these men had substantially lower FEV1 values (by 0.3- to 0.5L) than elderly men in Crapo's study. Mean peak flow was over 20% higher when compared with previous studies, suggesting greater initial expiratory effort by our subjects. The maximal inspiratory pressure (MIP) values were about 20% higher than those reported by the Cardiovascular Health Study, perhaps because five MIP maneuvers were always performed. CONCLUSION: Spirometry and MRP reference values used for elderly patients should come from population studies using similar techniques and with large numbers of subjects over age 65 years.

Age Distribution↗
PubMed1995

Migration models incorporating interdependence of movers.

"In this paper we describe a development of the Poisson model in which households are assumed to migrate independently, but the expected number of migrants is given by a Poisson distribution generalized by an empirically given household-size distribution.... The model is fitted to data on short-distance migration within the English county of Hereford and Worcester.... The data set used comes from the Special Migration Statistics (series II) produced as part of the 1981 British Census." The sparse nature of the data raises problems in assessing goodness of fit, because the deviance value is unusually low. This is tackled using simulation methodology.

Demography↗
PubMed1994

Adaptation in brain glucose uptake following recurrent hypoglycemia.

Brain glucose metabolism is impaired during hypoglycemia, but, if sustained, brain metabolism reverts to normal in animal models--data in man are lacking. We tested the hypothesis that adaptations occur to allow maintenance of normal rates of brain glucose uptake (BGU) following recurrent hypoglycemia in man. Twelve normal humans were studied over 4 days. On the initial day, arterial plasma glucose concentrations were decreased from 4.72 to 2.50 mmol/liter in five 0.56 mmol/liter steps. Cerebral blood flow, brain arteriovenous glucose difference, BGU, and cognitive function were quantitated at each step. BGU was initially impaired at the 3.61 mmol/liter glucose step (P = 0.04) and was antedated by increments in epinephrine that began at 4.16 mmol/liter (P = 0.03). The onset of hypoglycemic symptoms occurred during the 3.61 mmol/liter glucose step (P = 0.02), whereas tests of cognitive function generally deteriorated at the 3.05 mmol/liter step (P < 0.05). During the next 56 hr, mean glucose concentrations were kept at 2.9 +/- 0.1 mmol/liter and reached normal only during meals. The stepped clamp protocol was repeated beginning at 4.16 mmol/liter on the last day. No decrement in BGU was observed at any step; cognitive function was preserved until significantly lower glucose concentrations on the final day relative to the first (P = 0.04). Subjects remained asymptomatic of hypoglycemia until they reached a glucose concentration of 2.50 mmol/liter (P < 0.001 vs. day 1), while initial increments in all counterregulatory hormones were forestalled to lower glucose steps than on day 1. Therefore, adaptations occur that allow normal BGU and cerebral function to be maintained during recurrent systemic hypoglycemia. Counterregulatory events that should result in symptoms of hypoglycemia and increments in endogenous glucose production are prevented until extremely subnormal glucose concentrations.

Acclimatization↗
PubMed1994

Octreotide: a long-acting inhibitor of endogenous hormone secretion for human metabolic investigations.

Octreotide is a recently available, FDA-approved, long-acting analog of somatostatin. The efficacy and tolerability of octreotide were evaluated in a series of protocols in healthy volunteers to assess its suitability for use in clinical investigations involving short-term inhibition of endogenous hormone secretion. Prolonged (270 minutes) hyperglycemic clamps were used to assess octreotide-mediated suppression of glucose-stimulated endogenous insulin secretion. Compared with a saline-control infusion, octreotide (30 ng/kg/min) suppressed stimulated insulin (P < .0001) and C-peptide (P < .0001) concentrations to basal levels. During insulin-induced hypoglycemia (plasma glucose < 40 mg/dL), octreotide (30 ng/kg/min) effectively suppressed the secretion of glucagon (P < .05) and growth hormone (P < .0005). In islet cell clamp studies, octreotide (30 ng/kg/min) suppressed C-peptide (P < .001), glucagon (P < .01), and growth hormone concentrations to below basal (fasting) levels in all subjects. Subsequent infusion of exogenous insulin, glucagon, and growth hormone resulted in predictable and stable concentrations of each hormone during octreotide-mediated suppression of their endogenous secretion. Consistent with the long half-life of octreotide (approximately 90 minutes), the concentrations of all three hormones remained suppressed below basal levels throughout a 60-minute observation period following the termination of octreotide infusion. In separate high-dose octreotide infusion studies, octreotide (60 ng/kg/min) did not produce any apparent additional metabolic effects, but was associated with an unacceptable degree of gastrointestinal side effects.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Diminished brain glucose metabolism is a significant determinant for falling rates of systemic glucose utilization during sleep in normal humans.

Systemic glucose utilization declines during sleep in man. We tested the hypothesis that this decline in utilization is largely accounted for by reduced brain glucose metabolism. 10 normal subjects underwent internal jugular and radial artery cannulation to determine cerebral blood flow by N2O equilibrium technique and to quantitate cross-brain glucose and oxygen differences before and every 3 h during sleep. Sleep stage was graded by continuous electroencephalogram, and systemic glucose turnover was estimated by isotope dilution. Brain glucose metabolism fell from 33.6 +/- 2.2 mumol/100 g per min (mean +/- SE) before sleep (2300 h) to a mean nadir of 24.3 +/- 1.1 mumol/100 g per min at 0300 h during sleep (P = 0.001). Corresponding rates of systemic glucose utilization fell from 13.2 +/- 0.8 to 11.0 +/- 0.5 mumol/kg per min (P = 0.003). Diminished brain glucose metabolism was the product of a reduced arteriovenous glucose difference, 0.643 +/- 0.024 to 0.546 +/- 0.020 mmol/liter (P = 0.002), and cerebral blood flow, 50.3 +/- 2.8 to 44.6 +/- 1.4 cc/100 g per min (P = 0.021). Brain oxygen metabolism fell commensurately from 153.4 +/- 11.8 to 128.0 +/- 8.4 mumol/100 g per min (P = 0.045). The observed reduction in brain metabolism occurred independent of stage of central nervous system electrical activity (electroencephalographic data), and was more closely linked to duration of sleep. We conclude that a decline in brain glucose metabolism is a significant determinant of falling rates of systemic glucose utilization during sleep.

Activity Cycles↗
PubMed1994

A treatable cause of recurrent severe hypoglycemia.

OBJECTIVE: To see if glucocorticoid deficiency might explain increased insulin sensitivity causing severe brittle diabetes in two type I diabetic patients. CASES: We describe two patients who developed brittle diabetes characterized by recurrent severe hypoglycemia on small daily insulin doses with severe hyperglycemia on further insulin dose reduction. In both patients, insulin requirements had fallen markedly. RESULTS: Both patients were found to have glucocorticoid deficiency. In one patient, this was a result of hypopituitarism, in which hypoglycemia was aggravated by growth hormone deficiency. In the other patient, glucocorticoid deficiency was the result of primary adrenal failure. Resolution of brittle diabetes and restoration of normal insulin doses followed steroid replacement therapy in both patients. CONCLUSIONS: These patients emphasize the importance of seeking an organic cause for recurrent severe hypoglycemia. Increasing insulin sensitivity in type I diabetic patients should alert clinicians to the possibility of glucocorticoid deficiency.

Adult↗
PubMed1993

Decreased renal excretion of beta-hexosaminidase in adults with insulin-dependent diabetes mellitus and normal renal function.

The activities of three lysosomal hydrolases and creatinine levels were measured in the plasma and urine of 11 adults (mean age, 28.1 years) with insulin-dependent diabetes mellitus and 14 non-diabetic controls (mean age, 27.9 years). All of the patients were free of diabetic complications and non exhibited microalbuminuria. Fractional enzyme excretion (FEE) values between the two groups of subjects were calculated and compared for the following enzymes: beta-hexosaminidase (N-acetyl-glucosaminidase), beta-glucuronidase and alpha-galactosidase. The FEE value was calculated as the ratio of enzyme clearance to creatinine clearance. Relative to the non-diabetic control group, the FEE value for beta-hexosaminidase was approximately 2-fold lower (P = 0.02) in the diabetic subjects (means, 0.424 vs. 0.242, respectively). The FEE values for beta-glucuronidase and alpha-galactosidase were not significantly different (P > 0.4) between the diabetic and control groups. These easily measured biochemical parameters in blood and urine and the resultant FEE value for beta-hexosaminidase may provide a means of assessing subtle deteriorative changes in renal function which occur in the early stage of diabetes before the onset of clinically evident complications.

Adult↗
PubMed1993

Unaltered cerebral blood flow during hypoglycemic activation of the sympathochromaffin system in humans.

To determine if increases in plasma epinephrine and norepinephrine caused by hypoglycemia are associated with increments in cerebral blood flow (CBF), we measured CBF with positron emission tomography in normal humans at ambient fasting arterial plasma glucose levels and at clamped plasma glucose levels of 5.3, 3.5, and 2.8 mmol/l using the hyperinsulinemic, stepped hypoglycemic clamp technique. Despite significant increases in plasma epinephrine to 7,340 +/- 350 (SE) pmol/l and in plasma norepinephrine to 3.32 +/- 0.35 nmol/l, mean hemispheric CBF (41 +/- 1, 49 +/- 1, 48 +/- 2, and 51 +/- 3 ml x 100 g-1 x min-1) remained constant at the ambient (5.2), 5.3, 3.5, and 2.8 mmol/l glycemic levels, respectively. Furthermore, there was no correlation between CBF and either plasma epinephrine levels ranging from 160 to 10,580 pmol/l or plasma norepinephrine levels ranging from 0.56 to 5.10 nmol/l. Failure to demonstrate any dose-response relationship between plasma catecholamine levels and CBF argues against their primary role in cerebrovascular control during hypoglycemia.

Adult↗
PubMed1993

The challenge facing migration research: the case for a biographical approach.

"This article argues for an alternative conceptualization of migration which emphasizes its situatedness within everyday life. Our argument is constructed largely with the use of studies of internal migration from the developed world, but it must be stressed that the general theoretical argument could be extended to the study of migration in the developing world. Furthermore, our criticisms of current conceptualizations apply primarily to research into present-day migration rather than to more historical studies."

Demography↗
PubMed1993

Octreotide reverses hyperinsulinemia and prevents hypoglycemia induced by sulfonylurea overdoses.

Emergency therapy of sulfonylurea overdoses with glucose is often unsatisfactory because glucose stimulates insulin release and initiates a need for escalating quantities of hypertonic glucose to maintain normoglycemia. We tested the hypothesis that octreotide, an analog of somatostatin, would reverse hyperinsulinemia induced by a sulfonylurea overdose. Eight normal subjects received glipizide (1.45 mg/kg) on three occasions. Within 3 h, all subjects became hypoglycemic (< 50 mg/dL) and were initially treated with 50% dextrose followed by 1) dextrose infusion, 2) octreotide (30 ng/kg.min, iv), or 3) diazoxide (300 mg, iv, every 4 h). Euglycemia (85 mg/dL) was maintained with supplementary dextrose in treatment limbs 2 and 3. Insulin concentrations were 4-5 times greater with dextrose alone or in combination with diazoxide than with octreotide (P < 0.01). Dextrose requirements during diazoxide or dextrose alone were not different, but were both greater than those during octreotide treatment (P < 0.0001). All therapies were stopped at 13 h. Glucose levels remained above 3.6 mmol/L (65 mg/dL) in six of eight subjects receiving octreotide for the remaining 4 h. Glucose fell to below 3.6 mmol/L within 1.5 h of stopping either dextrose or diazoxide in each subject. Overall, octreotide reduced and in four of eight subjects entirely eliminated the need for exogenous glucose after a large overdose of glipizide. We conclude that octreotide is safe and effective and should be strongly considered as a logical therapeutic alternative for this metabolic emergency.

Adult↗
PubMed1993

Successful treatment of severe refractory sulfonylurea-induced hypoglycemia with octreotide.

OBJECTIVE: To test the clinical use of octreotide in the treatment of sulfonylurea-induced hypoglycemia. RESEARCH DESIGN AND METHODS: A case is reported of sulfonylurea-induced hypoglycemic coma in a nondiabetic subject, which was complicated by relapse of hypoglycemia after resuscitation with intravenous dextrose. Subcutaneous octreotide, 50 micrograms 12 hourly, suppressed stimulated endogenous insulin secretion, thereby preventing a further recurrence of hypoglycemia. RESULTS: No adverse effects of treatment were observed. CONCLUSIONS: These results suggest a significant role for octreotide as an adjunct to intravenous dextrose in the management of severe and refractory cases of sulfonylurea-induced hypoglycemia.

Adult↗
PubMed1993

Modelling sparse interaction matrices: interward migration in Hereford and Worcester, and the underdispersion problem.

The use of the Poisson regression approach to the modeling of migration is evaluated using 1981 census data on migration for Hereford and Worcester County, England. "It is shown that for this exceedingly sparse data set the deviance figures attained are very low, suggesting that there may be a problem of underdispersion....A simulation approach to the assessment of model goodness of fit is suggested, and the results from applying it to the Hereford and Worcester data set are described."

Demography↗
PubMed1993

Anthropometric, metabolic, and immunological effects of recombinant human growth hormone in AIDS and AIDS-related complex.

Metabolic and anthropometric changes induced by "pharmacological" versus "physiological" doses (5.0 vs. 2.5 mg, every other day) of recombinant human growth hormone (rhGH) were compared in 10 human immunodeficiency virus-positive patients with AIDS or AIDS-related complex. Five patients were randomly assigned to each treatment schedule in a 3-month prospective, double-blind clinical trial. Three of the 10 patients, none taking zidovudine and all with low initial CD4 counts, were withdrawn during the study due to acute opportunistic infections. During treatment, insulin-like growth factor-1 (IGF-1) levels increased significantly (p < 0.05) in the pharmacological hGH treatment group, whereas no significant change was observed in IGF-1 in the physiological dose rhGH group. In the pharmacological hGH treatment group, weight loss preceding the study was reversed (p < 0.05) in each of the four patients who completed the study. This weight gain was associated with increases (p < 0.05) in lean body mass and total body water, with concomitant decreases in fat mass (p < 0.05) and urinary nitrogen excretion. Muscle power and endurance, as assessed by standardized omnikinetic dynamometry, also improved. All four patients lost weight again (p < 0.05) 6 weeks after completion of the study and termination of rhGH treatment. Minor positive changes in body composition were also observed in the physiologic-dose hGH group. The pharmacological dose of hGH was associated with minor increments (p < 0.05) in fasting plasma glucose, insulin, and C-peptide concentrations, which were of negligible clinical significance.(ABSTRACT TRUNCATED AT 250 WORDS)

AIDS-Related Complex↗