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Biomedical subjects

S G Albert

Publications and source records attributed to S G Albert.

At least 19 recordsLinked to original sources
PubMed1989

Diabetic neuropathy and braille ability.

Thirty-five individuals with visual impairment due to diabetic retinopathy underwent neurologic examination with special emphasis on two-point discrimination and nerve conduction studies to determine whether concomitant peripheral neuropathy would interfere with their ability to read braille. Twenty-two individuals with insulin-dependent diabetes mellitus (9 men and 13 women) and 13 with noninsulin-dependent diabetes mellitus (4 men and 9 women) were evaluated. All had peripheral neuropathy; there were 4 with stage 1, 29 with stage 2, and 2 with stage 3 neuropathy. Two-point discriminatory ability appeared to be relatively well-preserved and at least 25 of the 35 individuals were able to learn to read standard or jumbo braille. Individuals with abnormalities in two-point discrimination (greater than 5 mm) were found to have abnormalities in braille reading. Individuals with visual impairment due to diabetes should not be discouraged from undertaking braille on the basis of apparent polyneuropathy.

Adult↗
PubMed1989

Vasopressin response to dehydration in Alzheimer's disease.

Alzheimer's disease is a progressive deterioration of neuropsychological functioning. One of the main neuropathological correlates of the disease is a drop-out of cholinergic neurons within the central nervous system. The neuropeptide that is responsible for water homeostasis and defense against dehydration, vasopressin, is also under direct cholinergic control. Several studies have suggested that in Alzheimer's disease there has been a trend toward lower vasopressin levels than in age-matched controls. In order to improve discrimination of normal from diminished vasopressin levels, nine subjects with Alzheimer's disease (mean age 65 +/- 2 years) and nine age- and sex-matched controls (68 +/- 3 years) underwent a mild provocative challenge of overnight fluid restriction. Individuals with Alzheimer's disease had a greater degree of dehydration, with overnight serum osmolality of 313 +/- 4 vs 300 +/- 3 Mosmol/kg, P = .01, and diminished "thirst" as measured by water ingested in one hour of ad libitum water intake. Eight of the nine with Alzheimer's disease had levels of vasopressin which, by extrapolation, appear to be subnormal for their serum osmolalities, whereas seven of the nine control subjects has vasopressin levels within or above the reference range (P less than .05). Elderly individuals with Alzheimer's disease may be at increased risk of dehydration during periods of fluid restriction due to the loss of normal physiological responses of "thirst" and vasopressin secretion.

Aged↗
PubMed1989

Exercise training in individuals with diabetic retinopathy and blindness.

Limited guidelines exist for rehabilitation programs for individuals with diabetes mellitus, blindness, and associated autonomic neuropathy. Abnormalities in autonomic function have been postulated to interfere with exercise conditioning and may predispose individuals to exercise-induced hypoglycemia. Twenty-nine individuals with diabetes mellitus underwent standardized noninvasive testing for the evaluation of cardiovascular autonomic function and graded exercise before entering a rehabilitation program. Inadequate responses of heart rate to respiratory variation were observed in 28 patients, abnormal heart rate responses to postural maneuvers were seen in 23, and postural hypotension was noted in nine. Individuals with symptomatic postural hypotension were able to exercise using a stationary bicycle, but developed hypotensive episodes on walking or prolonged standing. Blood glucose consistently decreased by a mean of 76 (+/- 9) mg/dl after each exercise session, even though low levels of exercise were performed (2.9 +/- 0.2 metabolic equivalents, for 28 +/- 1 min). There was no relationship between the degree of autonomic neuropathy and the level of blood glucose fall. There was, however, a significant correlation (r = -0.59, p = 0.001) between the decrease in blood glucose level and the amount of regular insulin used in the routine morning dose. Precautions were taken to avoid hypoglycemia, and insulin and diet were adjusted accordingly to prevent severe hypoglycemic reactions.

Adolescent↗
PubMed1988

Venous thromboembolism and transient thrombocytopenia in a patient with diabetes insipidus treated with desmopressin acetate (DDAVP).

A 22 year-old woman with diabetes insipidus on chronic therapy with desmopressin acetate (DDAVP) developed recurrent venous thromboembolism and transient thrombocytopenia temporally related to the administration of DDAVP. Large increases in plasma von Willebrand factor (vWF), vWF-activity, and relative increases in the concentrations of the larger multimeric forms of vWF-antigen were observed, as well as a plasma factor which sensitized normal platelets to undergo spontaneous aggregation in vitro. Additional studies showed that the patient's plasma retained the platelet aggregation inducing activity after selective removal of vWF by immunoabsorption. The nature of the platelet activating factor and the relationship of this factor and the excessively increased and transiently abnormal vWF to the recurrent venous thromboembolism in this patient remain uncertain. Although the findings do not implicate definitively DDAVP in the elevation of vWF in this patient, it is suggested that its use be considered with caution in patients with diabetes mellitus and increased levels of vWF.

Adult↗
PubMed1987

Thyroid dysfunction during chronic amiodarone therapy.

Clinical and laboratory features of 99 patients receiving long-term amiodarone therapy were analyzed to determine which individuals may be at a high risk for developing amiodarone-induced thyroid dysfunction. The group of 68 men and 31 women was followed up for an average of 27 months (range 3 to 60). There were no differences in age, sex, dose of amiodarone, type or severity of underlying heart disease or baseline serum thyroxine levels in patients who developed hypothyroidism (n = 32) or hyperthyroidism (n = 5) or remained euthyroid (n = 62). Baseline serum thyrotropin levels were statistically higher in patients who became hypothyroid, but there was considerable overlap with the other patient groups. Serum reverse triiodothyronine (reverse T3), which has been suggested to be a marker of amiodarone efficacy, correlated directly with serum thyroxine levels, and was not an independent variable. There was no pattern to the time course for development of thyroid dysfunction, which occurred in 49% of those followed up and developed as early as 1 month or, in one individual, as late as after 3 years of amiodarone therapy. There are few guidelines for replacement therapy in patients with amiodarone-induced hypothyroidism. L-thyroxine dosage was adjusted cautiously in these high risk individuals to achieve serum thyroxine levels within the reference range of euthyroid individuals taking amiodarone: the mean dosage required was 136 micrograms/day. Normalization of serum thyrotropin (TSH) would have required doses of L-thyroxine that were judged to be excessively high.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1984

Phenothiazine-induced hyponatremia in the elderly.

The syndrome of severe hyponatremia associated with neurological deficits is especially ominous in an elderly population. During a heat spell in summer, 2 elderly patients from a nursing home who were chronically taking phenothiazines were admitted with neurological symptoms due to hyponatremia. We sought the prevalence of hyponatremia in this chronic care facility. Those patients on phenothiazines had a significantly lower level of serum sodium than the remaining nursing home residents. Those patients on phenothiazines may be at increased risk to develop hyponatremia when they are subjected to further fluid-retaining stresses.

Aged↗
PubMed1984

Cytochalasin B does not serve as a marker of glucose transport in rabbit erythrocytes.

Glucose inhibitable cytochalasin B binding to erythrocyte membranes has been used as a marker of the glucose transporter. Glucose transport and cytochalasin B binding in rabbit erythrocytes differ from those activities found in human erythrocytes. We evaluated the uptake of 3-0-methylglucose and found similar Km (4.81 +/- 1.20 mM (SEM) and 6.59 +/- 0.72 mM) though significantly different Vmax (5.2 +/- 0.7 nM . min-1/10(9) cells and 234 +/- 13 nM X min -1/10(9) cells, p less than 0.001) for rabbit and human erythrocytes, respectively. Equilibrium binding of cytochalasin B to human erythrocyte membranes demonstrates a high affinity cytochalasin B binding site (Kd 38.6 +/- 22.7 nM) which is displaced by glucose. No comparable glucose inhibitable cytochalasin B site exists for rabbit erythrocyte membranes. Photoaffinity labeling of cytochalasin B confirms the presence of a glucose inhibitable cytochalasin B binding site in human, but not rabbit erythrocyte membranes. Cytochalasin B binding is a useful method in the identification of the glucose transporter in human cells, but the technique may be less useful in other species.

3-O-Methylglucose↗
PubMed1982

The effect of insulin on glucose transport in rabbit erythrocytes and reticulocytes.

Insulin binding and 3-0-Methylglucose transport have been studied in erythrocyte- and reticulocyte-enriched fractions of blood cells in order to determine if the increased number of insulin binding sites in reticulocytes is associated with a glucose transport response to insulin. In these experiments rabbit reticulocytes demonstrate an eightfold increase in total insulin receptors when compared to erythrocytes. Glucose transport activity in the erythrocyte has Km of 3.2 mM. Reticulocytes demonstrate a saturable glucose transport activity of lower affinity, Km 18.9 mM. Neither the erythrocyte, nor the the reticulocyte glucose transport activity, was capable of an increased response to insulin. the low affinity glucose transport activity in reticulocytes could allow a fourfold increase in facilitated glucose transport at supraphysiological glucose concentrations that might occur in poorly controlled diabetes mellitus.

Animals↗
PubMed1982

Immunological characterization of catfish (Ictalurus punctatus) insulin and proinsulin.

1. Insulin and insulin intermediates were isolated and characterized from catfish (Ictalurus punctatus) pancreatic islets. 2. An antibody developed to this catfish insulin allowed the identification of proinsulin, and insulin intermediates. 3. Amino acid composition of the isolated insulin intermediates was similar to the calculated amino acid composition of proinsulin, as determined from the analyses of the separate A, B and C chains.

Amino Acids↗
PubMed1979

Proinsulin precursors in catfish pancreatic islets.

The purpose of these experiments was to determine whether insulin-related peptides, larger than proinsulin, could be detected in pancreatic islet cells. Catfish pancreatic islets were incubated with radiolabeled amino acids. After 15- to 60-min incubation, two acid-alcohol-extractable peptides, larger than proinsulin, were detected which were approximately of Mr = 12,000 and 11,000 (12 K and 11K, respectively). They migrated as single polypeptide chains by sodium dodecyl sulfate-urea polyacrylamide gel electrophoresis under reducing conditions, and were therefore not aggregates of insulin or proinsulin. The 12 K protein had identical mobility with catfish preoproinsulin synthesized in a wheat germ cell-free system. On standard electrophoresis at pH 8.9, the 12 K protein migrated separately from proinsulin and was at least 65% one protein with two to three minor contaminants. The 12 K and 11 K proteins were chemically related to insulin and proinsulin as shown by tryptic peptide analysis, using cation exchange resin chromatography, and by two-dimensional tryptic peptide maps. Analysis of the tryptic digest of the 12 K protein, compared to proinsulin after leucine aminopeptidase treatment, suggested that the NH2 terminus of the larger protein was different from that of proinsulin. These peptides were specifically bound to anti-insulin antibody. The binding was only 5 to 8% of the protein added, but was specific for the 12 K and 11 K proteins when the immunoprecipitates were examined by electrophoresis and not from contaminating proinsulin. During the continuous incubation of the islets with [3H]leucine, 12 K and 11 K proteins were synthesized in the cell before proinsulin. When islets were first incubated with [3H]leucine for 30 min followed by incubation with excess unlabeled leucine, the 12 K and 11 K proteins appeared to show a precursor-product relationship to proinsulin and insulin. Even when total islet protein synthesis was inhibited by cycloheximide (100 microgram/ml), proinsulin continued to be synthesized for up to 2 h. This suggested that the conversion of the proinsulin precursors to proinsulin in the fish is a post-translational event.

Animals↗
PubMedDate not supplied

A model clinical program for patients with diabetes and vision impairment.

A program was developed to improve independence, self-esteem, and glycemic control in patients with diabetes and blindness. Twenty-nine individuals with both insulin-dependent and noninsulin-dependent diabetes mellitus entered 12-week programs that included education focusing on diabetes self-management skills for the visually impaired, monitored exercise sessions, and group support. Glycated hemoglobin values fell from 13.0% +/- 0.6% (SEM) to 11.4% +/- 0.5% (P = .001). Exercise tolerance in a 12-minute walk test improved from 0.48 +/- 0.04 to 0.64 +/- 0.05 miles (P = .001). Marked improvements occurred in psychosocial indices, demonstrated through changes in the Rand Mental Health Index from 155 +/- 6 to 174 +/- 5 (P = .0001), the Rosenberg Self-Esteem Scale from 22 +/- 1 to 19 +/- 1 (P = .001), the Zung Depression Scale from 0.50 +/- 0.02 to 0.44 +/- 0.02 (P = .001), and the Diabetes Self-Reliance Test from 60 +/- 3 to 74 +/- 2 (P = .0001).

Adaptation, Psychological↗
PubMedDate not supplied

Psychosocial profiles in patients with visual impairment due to diabetic retinopathy.

The psychological impact of vision loss due to diabetic retinopathy is compounded by the loss of diabetes self-management skills. The appropriate role and timing for rehabilitative intervention has not been determined. Twenty-nine individuals with diabetes mellitus, 16 with stable visual impairment and 13 with fluctuating and transitional visual impairment, underwent psychological assessment before and after entering into a specially designed rehabilitation program. Low levels of performance were rehabilitation program. Low levels of performance were demonstrated by the Rosenberg Self-Esteem Scale and the Diabetes Self-Reliance Test in both groups. The Minnesota Multiphasic Personality Inventory, the Zung Self-Rating Depression Scale, and the Rand Mental Health Index suggested that subjects with stable vision impairment were moderately compensated relative to the transitional group, although the former group may have been totally blind. Both groups demonstrated significant improvements in psychological profiles after the program. It is suggested that a rehabilitation program may be of clinical benefit early in the course of vision loss associated with diabetic retinopathy.

Adult↗