Effects of insulin and glucose on cultured rat hepatocyte gene expression

We previously used isolated adult rat hepatocyte cultures to study the ability of glucose to induce several hepatic mRNAs. However, we found that the optimal insulin concentration required to obtain the glucose effect was greater than 10,000 microU/ml. To test the hypothesis that the requirement for high concentrations of insulin in the culture was due to rapid loss of insulin in hepatocyte cultures, serial measurements of insulin were made at different media insulin concentrations (0-500,000 microU/ml) and glucose concentrations (5.5 and 2.75 mM). In addition, a dose-response relationship was established between media insulin concentrations and the pattern of mRNAs present in the hepatocytes determined by two-dimensional gel electrophoresis of in vitro translation products. We found that at low insulin concentrations (less than 1000 microU/ml), greater than 80% of the insulin was lost to the glassware, whereas at high initial insulin concentrations, approximately 23% of the insulin was lost to the glassware. Placement of media into the hepatocyte culture led to further insulin disappearance with a half-life for insulin of 41.5 h at 10,000 microU/ml and 13.8 h at 100 microU/ml. We found 16 mRNAs were altered by insulin at 5.5 mM glucose and 9 mRNAs were changed by insulin at 27.5 mM glucose. After taking into consideration the distributional and metabolic losses of insulin, all but one mRNA responded to insulin within the physiologic range of portal insulin (less than 1-94 microU/ml). Our data indicate that the hepatocyte culture is an excellent model to study the physiologic effects of insulin on hepatic gene expression.     

Endocrinology in aging

Aging is a time of reduced adaptability to metabolic perturbation. This is particularly true in endocrinology which, after all, is the science of chemically regulated biologic systems. There is no evidence that equilibrium concentrations of the principal hormones are altered with age. However, the systems utilized to reach those equilibria become progressively taxed, and new equilibria may be achieved reflecting that regulatory problem. Thus, with advancing age there are significant alterations in hormone production, metabolism, and action. Some of these changes may play a role in the pathophysiology of senescence, although the evidence for that is limited. The magnitude of age-related alterations is highly variable and sex dependent. Whereas only subtle changes occur in pituitary dynamics, adrenal gland physiology, and thyroid function, the changes in glucose homeostasis, reproductive function, and calcium metabolism are more apparent. In the elderly, the interpretation of endocrine tests should reflect the nutritional status of the patient and the presence of coexisting illnesses. In this review, we describe the principles of endocrinology in the geriatric population and elaborate on the changes in specific glandular functions with aging. We also define strategies of evaluation and management protocols appropriate for the elderly with suspected endocrine dysfunction.     

Towards Single-Tablet Therapy for Type 2 Diabetes Mellitus

Type 2 diabetes mellitus emerges as a result of multiple pathophysiologic changes. If the pharmacotherapy of type 2 diabetes should be tailored to the underlying pathophysiology, it would be necessary to use a combination of agents with complementary mechanisms of action. The two principal defects in type 2 diabetes are insulin deficiency and insulin resistance. Therefore, combining an insulin-providing agent with an insulin-sensitizing agent will augment the efficacy of current antihyperglycemic agents. This is the rationale for the development and marketing of sulfonylurea/metformin combination tablets.Randomized double-blind clinical trials have shown the safety and efficacy of these fixed combination tablets in both drug-naive individuals as well as in those individuals not achieving glycemic goals on sulfonylurea or metformin monotherapy. These studies have also shown that these tablets may be associated with better postprandial glycemic control compared with monotherapy. However, the risk of hypoglycemia is increased with the use of combination tablets, especially in drug-naive individuals with baseline glycosylated hemoglobins of <8.0%. Combining two insulin-sensitizing agents that have different mechanisms of action and that target different biochemical pathways, would also enhance efficacy. This can be accomplished by combining metformin with rosiglitazone or pioglitazone. The recently developed fixed formulation tablet of metformin/rosiglitazone is available for use as second-line therapy in individuals who have not reached their glycemic goals while on metformin. The advantages of combining several agents in one tablet include convenience and enhanced adherence to therapy. The main disadvantage is the loss of administration flexibility.     

Cytogenetic studies in patients with secondary leukemia/dysmyelopoietic syndrome after different treatment modalities

Cytogenetic studies of 68 patients who developed secondary leukemia (SL)/dysmyelopoietic syndrome (DMS) after extensive chemotherapy and/or radiation therapy as well as patients who developed SL/DMS without such treatment showed that those patients who received radiation alone or with chemotherapy had more extensive numerical and structural abnormalities than those who received only chemotherapy. In terms of the specific chromosomal abnormalities, there are no differences between the various treatment groups. Hypodiploidy is the most common form of aneuploidy in these patients, with the most common numerical abnormality being the loss of chromosome 7. The most common structural abnormalities involved chromosomes 3 and 5. When compared with patients with de novo leukemia and DMS, the chromosomal abnormalities in these patients are more complex and extensive. Serial studies revealed that cytogenetic abnormalities do not precede the development of hematologic changes by significant time periods.     

Human platelet fibrinogen: purification and hemostatic properties

Conditions were developed in which 80% to 90% of platelet fibrinogen could be routinely purified in nondegraded form from the fluid phase of platelet suspensions stimulated with the calcium ionophore, A23187, in the presence of calcium, leupeptin, and prostaglandin E1. Fibrinogen was separated from other released proteins by chromatography on diethylaminoethanol (DEAE)-cellulose using a continuous pH and ionic strength gradient. Purified platelet fibrinogen, greater than 98% homogeneous by immunoelectrophoresis and sodium-dodecyl sulfate- polyacrylamide gel electrophoresis (SDS-PAGE), consisted of intact A alpha, B beta and gamma A chains, but not gamma' chains, and was 95% to 96% clottable. Platelet fibrinogen was shown to compete for the binding of radiolabeled plasma fibrinogen to ADP-activated platelets in a manner identical to that of unlabeled plasma fibrinogen itself. Also, at equivalent protein concentrations, platelet and plasma fibrinogens supported platelet aggregation to an equivalent extent. Based upon these results, we conclude that there is no significant difference between platelet and plasma fibrinogen with respect to their size, their clottability, their affinity for the activated platelet fibrinogen receptor, or their capacity to support subsequent platelet aggregation.     

Use of a vacuum tumescence device in the management of impotence

This study evaluated the use of a vacuum tumescence device in the treatment of impotence in older men. Twenty couples with sexual dysfunction due to erectile impotence and who were interested in restoration of sexual function were treated by providing them with both a vacuum tumescence device to engorge the penis and an obstructing band to impede venous return. Nineteen patients established firm to hard erections lasting an average of 16 minutes and were able to have satisfactory coitus with vaginal ejaculation an average of three times per month. The penile-brachial pressure index, supine and after exercise (a measure of the adequacy of penile arterial flow), exhibited a significant increase following six month's use of the vacuum tumescence device. The only significant complications were mild, self-limited hematomas on three occasions of use. Thus in this limited series the vacuum tumescence device provided a well-accepted, relatively inexpensive therapeutic approach to impotence.     

Ulnar nerve injuries of the hand producing intrinsic muscle denervation on magnetic resonance imaging

Muscle and nerve injuries in the hand may be difficult to detect and diagnose clinically. Two cases are reported in which magnetic resonance imaging showed ulnar nerve injury and intrinsic hand muscle denervation. The clinical, anatomical and radiological features of injury to the deep motor branch of the ulnar nerve and associated muscle denervation are discussed and illustrated.