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Biomedical subjects

J Silverstein

Publications and source records attributed to J Silverstein.

48 records · Page 3Linked to original sources
PubMed1984

Renal function in rats chronically exposed to high altitude.

Chronic exposure of rats to a simulated altitude of 18,000 ft (5,500 m) results in severe polycythemia and consequent reduction of the plasma fraction. However, glomerular filtration rate is usually well maintained. This study was conducted to determine whether an increase in effective renal blood flow (ERBF) plays a role in maintaining a normal glomerular filtration rate in the chronically hypoxic rats. Various measurements of renal function were made in conscious trained and chronically catheterized animals. After exposure to high altitude for 30 days, hematocrit ranged from 64 to 77%. Despite this severe reduction in the plasma fraction, however, renal plasma flow decreased by only 25%, primarily owing to an increase in ERBF. The glomerular filtration rate was within the normal range. Since blood pressure remained unchanged, the increase in ERBF must have resulted from renal vasodilation. Acute removal of the hypoxic stimulus did not reverse the increased ERBF, suggesting that the vasodilation may have been of structural origin.

Altitude↗
PubMed1980

Islet cell and other organ-specific antibodies in U.S. Caucasians and Blacks with insulin-dependent diabetes mellitus.

Islet cell antibodies (ICA) were detected in 168 (33%) of 504 patients with insulin-dependent diabetes mellitus (IDDM). Mean age of onset of IDDM was 8.6 +/- 0.2 yr and mean age at testing was 13.4 +/- 0.3 yr. None of 162 controls without diabetes (mean age 21.8 +/- 0.9 yr) had ICA. Caucasian patients (404) had a 74% frequency of ICA within 3 mo of diagnosis and an overall ICA frequency of 36%. These results were similar to those reported from Europe. Black patients (100) had lower frequencies of ICA (P < 0.01) and thyroid antibodies (P < 0.05). Caucasian patients with onset of IDDM before 5 yr of age (107) had a lower frequency (P < 0.01) of ICA (21%) than those (297) with a later age of onset (42%). Patients with persistent ICA beyond 5 yr of IDDM had increased frequencies of gastric parietal and adrenal cortex cell antibodies. Thyroid microsomal antibodies were less frequent (P < 0.05) in blacks (4%) than in Caucasians (20%). The former did not have adrenal antibodies. Similar ICA frequencies among Caucasians with IDDM in the U.S. and in Europe suggest that etiologic factors are similar in the two geographic regions. The lower frequencies of ICA in patients with IDDM onset before 5 yr of age suggest that some of these patients may have a different etiology and/or a more rapid disappearance of islet cell antigens than patients with a later onset.l The lower ICA frequencies in black patients can be explained by heterogeneity of IDDM in this group and by admixture of IDDM susceptibility genes from the Caucasian genome to the black genome.

Adolescent↗
PubMedDate not supplied

Effects of prenatal alcohol exposure at school age. II. Attention and behavior.

Alcohol, a potent teratogen, has been suggested as an etiologic agent in attention deficit disorder with hyperactivity (ADHD), which is often diagnosed in children with fetal alcohol syndrome (FAS) and in children of alcoholics. We studied attentional and behavioral factors associated with diagnosis of this disorder in children selected from a predominantly low-income, black population who were tested as part of a longitudinal follow-up of children with prenatal alcohol exposure. Sixty-eight children with a mean age of 5 years 10 months, born to three groups of mothers, were assessed. These groups consisted of: a) women who reported not drinking during pregnancy (n = 21), b) women who reported drinking throughout pregnancy (n = 25), and c) women who reported drinking an equivalent amount but who stopped drinking after educational intervention during the second trimester (n = 22). Dimensions assessed included factors related to attention on a computerized task, impulsivity, and the presence of psychiatrically significant internalizing and externalizing behaviors. In addition, free play and mother-child interactions were video-taped, and evidence of overactive and noncompliant behaviors were noted. Hyperactivity and impulsive behavior were not evident. Results indicated that children exposed throughout pregnancy showed deficits in the ability to sustain attention and were more often described by teachers, although not by their mothers, as showing attentional and behavioral problems. Problems in both internalizing and externalizing behaviors also were noted by teachers. However, when current drinking was controlled, only externalizing behaviors remained different by group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Diabetologists' judgments of diabetic control: reliability and mathematical simulation.

In study 1, laboratory and supervised blood or urine test data from actual cases were used to develop patient profiles. Seven diabetologists from the same institution rated the diabetic control of 125 profiles on a four-point scale (1 = poor, 2 = fair, 3 = good, 4 = excellent). Six of the 7 diabetologists demonstrated adequate intra- and interrater reliability. Study 2 assessed the reliability of judgments of diabetic control made by diabetologists working in two different settings. There were 9 raters from institution 1 and 8 from institution 2. The impact of the amount and type of information on judgment reliability was evaluated by developing two types of profiles. The test form contained only laboratory and supervised blood or urine test data similar to that utilized in study 1. The history form contained this information as well as other descriptive data typically available to diabetologists. The 17 diabetologists rated 125 anonymous profiles on each of two separate occasions approximately 1 wk apart. On one occasion they rated profiles presented on the test form. On the other occasion they rated profiles presented on the history form. As in study 1, the diabetologist raters demonstrated adequate intra- and interrater reliability. Intrarater reliability was somewhat better when rating test form profiles compared with history form profiles. Reliability was not higher within than between institutions. An analysis of the relative contribution of different diabetes control indices to the diabetologists' judgments indicated that HbA1 influenced raters' judgments at both institutions more than any other single variable.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMedDate not supplied

Financial indicators.

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Costs and Cost Analysis↗