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Biomedical subjects

P C O'Brien

Publications and source records attributed to P C O'Brien.

At least 235 records · Page 13Linked to original sources
PubMed1989

Diagnostic interpretation of the intravenous tolbutamide test for insulinoma.

The plasma glucose and insulin responses to intravenous administration of tolbutamide in patients with insulinoma and healthy control subjects were compared to determine the sensitivity and specificity of the intravenous tolbutamide test for the diagnosis of insulinoma. The records of 406 healthy persons without concurrent disease known to affect glucose homeostasis or insulin concentrations and 41 patients with histologically confirmed insulinoma who underwent standard intravenous tolbutamide testing during the period from 1976 to 1986 were reviewed. The 5th percentile of the mean of plasma glucose levels at the 120-, 150-, and 180-minute points (G120-180) after injection of tolbutamide was 55 mg/dl for lean and 62 mg/dl for obese control subjects. With 95% specificity, the sensitivity of these criteria was 95% for lean and 100% for obese patients with insulinoma. Minimal differences were observed between men and women. At 95% specificity, the sensitivities were less for the ratio of the 180-minute plasma glucose to fasting plasma glucose level (64% in lean and 75% in obese patients), for mean of plasma insulin at the 120-, 150-, and 180-minute points (IRI120-180) (53% in lean and 36% in obese patients), for maximal insulin concentration (27% in lean and 31% in obese patients), for increase in insulin concentration above basal (18% in lean and 23% in obese patients), and for the combined criteria of the 5th percentile of G120-180 and the 95th percentile of IRI120-180 (47% in lean and 73% in obese patients).(ABSTRACT TRUNCATED AT 250 WORDS)

Adenoma, Islet Cell↗
PubMed1989

Self-administered alcoholism screening test (SAAST): comparison of classificatory accuracy in two cultures.

Results of stepwise discriminant analyses of the Self-Administered Alcoholism Screening Test (SAAST) administered to 181 alcoholics and 123 nonalcoholics in Mexico City were compared with results of a similar analysis of a sample in the United States (Rochester, MN). With sensitivities of 90% and 95%, specificities were 91.1% to 99.2% in the Mexican sample for total score and a nine-item version derived from the Mexican sample gave specificities between 95.1% and 99.2% at 90% and 95% sensitivities, as with the Rochester sample. The two items with greatest predictive power were the same in both cultures.

Adult↗
PubMed1989

Meaningful degrees of prevention or improvement of nerve conduction in controlled clinical trials of diabetic neuropathy.

Use of nerve conduction in assessing therapy in preventing or ameliorating neuropathy is desirable because abnormalities of nerve conduction are associated with severity of neuropathic symptoms and deficits. Assuming that a therapy is associated with a statistically significant improvement of nerve conduction, what degree of nerve conduction change is clinically meaningful? We suggest that in controlled clinical trials, a mean change of 2 points on the neurologic disability score is clinically detectable and meaningful. Based on our previously published cross-sectional epidemiological data, this corresponds to a change of motor nerve conduction velocity of the average ulnar median and peroneal nerves of 2.9 m/s and peroneal nerve of 2.2 m/s. The corresponding changes of amplitude were 1.2 and 0.7 mV, respectively. Smaller degrees of nerve conduction change were found when only insulin-dependent patients were evaluated.

Clinical Trials as Topic↗
PubMed1989

Statistical analysis in clinical laboratory medicine: fundamentals and common uses.

Medical research studies may be classified into two broad categories: descriptive and inferential. Descriptive studies are intended to describe the characteristics of only the study group, using observations obtained from every member of the group. Inferential studies, on the other hand, are designed to enable the investigator to use observations from selected individuals (a sample) to make conclusions about the larger group (population) from which they were drawn. The first part of this paper deals with descriptive studies, focusing on summary statistics and graphic techniques. The remainder deals with inferential studies. We start by describing how characteristics of the population may be estimated from characteristics of a small number of its members, which are randomly selected. These principles are then applied to the problem of testing hypotheses about the population by use of some of the more common testing procedures. These include t tests, regression, chi-square tests, evaluating a new diagnostic procedure, estimating normal values, survivorship studies, and sequential methods.

Data Interpretation, Statistical↗
PubMed1988

Endothelial function and aqueous humor flow rate in patients with Fuchs' dystrophy.

Using a two-dimensional scanning fluorophotometer, we studied 50 subjects with symmetric ocular involvement of Fuchs' dystrophy without epithelial edema. Twenty-six subjects with confluent or nearly confluent cornea gutata with increased corneal thickness and 24 subjects with mild to moderate cornea guttata with normal corneal thickness were compared to normal control subjects. There were no statistically significant differences in endothelial permeability between the three groups. Corneal thickness was significantly increased in the subjects with confluent to nearly confluent guttae, however. These results suggest that endothelial pump function may be affected in subjects with advanced cornea guttata with stromal edema.

Aqueous Humor↗
PubMed1988

Factors associated with infantile hypertrophic pyloric stenosis.

We examined perinatal factors in relation to the rise in incidence of infantile hypertrophic pyloric stenosis among children in Olmsted County, Minnesota, during the period from 1950 through 1984. Primogeniture was associated with male infants but not female infants; some factor related to primogeniture, such as breast-feeding, may be etiologically important. Our data did not support a role for maternal disease, use of doxylamine succinate-pyridoxide hydrochloride (Bendectin), or an infectious process. Further study should be directed toward environmental factors associated with primogeniture.

Birth Order↗
PubMed1988

Potential incretins.

A greater plasma concentration of insulin after isoglycemic enteral than after parenteral administration of glucose is called the incretin effect. The primary mediator of this effect, gastric inhibitory polypeptide, may not account for the complete manifestation of this phenomenon. We evaluated other gastroenteric polypeptides with respect to a differential response to oral ingestion of glucose and intravenous administration of glucose at rates that achieved arterial plasma glucose concentrations matched to those from orally administered glucose. Gastrin, peptide histidine methionine, peptide YY, and neurotensin showed increases in plasma concentrations in response to oral ingestion of glucose but not to intravenous administration of glucose. Vasoactive intestinal polypeptide showed no increased concentration in response to either oral or intravenous administration of glucose. The differential responses to orally and intravenously administered glucose noted in the former gastroenteric polypeptides qualifies them as potential mediators of the incretin effect.

Administration, Oral↗
PubMed1988

Surgical resection of carotid body tumors: long-term survival, recurrence, and metastasis.

We retrospectively reviewed a 20-year experience with 59 carotid body tumors in 55 patients examined at our institution in order to determine the long-term results of surgical resection, including the rates of distant metastasis, local recurrence, and long-term survival. Complete surgical excision was possible in 52 of the 55 patients (95%). Perioperative mortality was only 2% (1 of 59 procedures), and no operative deaths occurred during the last 10 years of the study. Survival of patients after resection of a carotid body tumor was equivalent to that for sex- and age-matched control subjects. Only one patient (2%) had development of metastatic disease during long-term follow-up. Three patients (6%) had recurrence of the carotid body tumor after complete excision. All recurrent tumors were observed in patients with multiple paragangliomas or a family history of cervical paragangliomas. Therefore, we advocate early surgical resection of all carotid body tumors in low-risk patients. Such early resection maximizes the possibility of cure and minimizes the risks of neurovascular complications associated with large and neglected tumors.

Adolescent↗
PubMed1988

New perspectives on rural EMT defibrillation.

In recent years, several studies have produced contradictory data regarding the impact of emergency medical technicians trained in defibrillation on hospital admission and dismissal survival rates in rural areas. Fourteen communities (service area populations, 4,000 to 36,000) in rural south-eastern Minnesota participated in a two-year crossover study to further define the factors necessary for success. Automatic external defibrillators were used to defibrillate and record patient rhythms in the treatment group and to only record in the control group. Although six of 36 patients (17%) in ventricular fibrillation who experienced a witnessed arrest survived in communities using automatic external defibrillators, compared with one of 27 (4%) in the control group, five of the six survivors were from a single large community with a 911 system, full-time emergency medical technicians, police first-responders, and a well-equipped emergency facility. Our data suggest that certain prerequisites, especially CPR prior to ambulance arrival and collapse to defibrillation times of less than ten minutes, are clearly essential to produce significant benefits from emergency medical technicians trained in defibrillation in rural communities.

Aged↗
PubMed1988

Trends in infantile hypertrophic pyloric stenosis in Olmsted County, Minnesota, 1950-1984.

In the 35-year period, 1950-1984, 154 Olmsted County, Minnesota, infants were diagnosed with definite infantile hypertrophic pyloric stenosis (IHPS). Patients were identified using outpatient and inpatient records of all providers of care to the circumscribed population, and ascertainment was complete insofar as diagnosed cases are concerned. The overall incidence of IHPS was 2.6 per 1000 person-years (95% confidence interval: 2.2-3.0), with a male:female ratio of 4.1:1. A dramatic rise in incidence was seen among male infants over the study period, but not for females, so that by 1980-1984 the rates for the two sexes were 6.2 and 0.9 per 1000 person-years, respectively. Improvements in diagnostic capabilities and case identification may have occurred but seem unlikely to entirely account for these changes. Aetiologic hypotheses should reflect the different trends for male and female infants.

Cohort Studies↗
PubMed1988

Role of gastric inhibitory polypeptide in postprandial hyperinsulinemia of obesity.

To assess the contribution of gastric inhibitory polypeptide (GIP) to the postprandial hyperinsulinemia of obesity, secretion rates of GIP (generated from kinetic analyses from infusions of porcine GIP) and insulin (from C-peptide applied to a validated kinetic model) to meals of 3 sizes were determined in 10 obese (5 male and 5 female) and 10 lean, sex- and age-matched healthy subjects. Although the postprandial secretion rates of GIP were greater in obese subjects (P = 0.03), postprandial concentrations of GIP were not. The latter may be explained by the greater volume of distribution of GIP in obese subjects (P = 0.036). Secretion rates and volume of distribution of GIP were correlated (r = 0.652, P less than 0.01). Despite excessive integrated postprandial (P = 0.010) insulin concentrations, insulin secretion was not significantly different between obese and lean subjects. We conclude that 1) although postprandial plasma GIP concentrations are normal, GIP secretion is increased in obesity, 2) the postprandial hyperinsulinemia of obesity is not due to excessive insulin secretion but is likely secondary to altered insulin clearance, and 3) GIP cannot account for the hyperinsulinemia of obesity through its insulinotropic action.

Adult↗