Therapeutic effects of dehydroepiandrosterone (DHEA) in diabetic mice

Dehydroepiandrosterone (DHEA), a major adrenal secretory steroid in humans, was therapeutic when fed in a concentration of 0.4% to C57BL/KsJ mice with either non-insulin-dependent or insulin-dependent diabetes. Genetically diabetic (db/db) mice of both sexes develop obesity and a glucose intolerance and hyperglycemia associated with insulin resistance by 2 mo of age, and exhibit beta-cell necrosis and islet atrophy by 4 mo. In contrast, DHEA feeding initiated between 1 and 4 mo of age, while only moderately effective in preventing obesity, did prevent the other pathogenic changes and effected a rapid remission of hyperglycemia, a preservation of beta-cell structure and function, and an increased insulin sensitivity as measured by glucose tolerance tests. DHEA feeding was also therapeutic to normal C57BL/KsJ male mice made diabetic by multiple low doses of streptozotocin (SZ). While DHEA treatments did not block either the direct cytotoxic action of SZ on beta-cells or the development of insulitis, the steroid significantly moderated the severity of the ensuing diabetes (reduced hyperglycemia and water consumption, and increased plasma insulin and numbers of residual, granulated beta-cells.     

Utility scaling of intracranial reinforcement duration.

The purpose of the investigation was to apply signal detection theory to the utility scaling of train duration, a parameter of intracranial self-stimulation. Each of the four Charles River rats used was unilaterally implanted with bipolar stainless steel electrodes directed at the medial forebrain bundle. Prior to testing, the animals were trained in a two-choice paradigm to discriminate for brain stimulation between high and low frequency tones. Train duration utility functions were generated with each rat by systematically changing the reinforcement duration associated with the two classes of correct responses over a series of payoff matrices and observing corresponding shifts in response bias, the measure of relative reinforcement strength. Incorrect responses were followed by uniform short time outs. Least squares analysis found that negatively accelerating power functions (correlation coefficients were significant, p<0.01) described the relationship established between the reinforcement ratios (formed by the train durations associated with the two correct response alternatives) and the obtained betas (i.e., response bias).     

Triiodothyronine uptake assay with immobilized triiodothyronine antibody as the bound-free separating agent.

Available systems for evaluation of degree of unsaturation of thyroxine-binding globulin are hampered at the bound-free separation step. In current assays, inorganic sorbants or ion-exchange resins are used to separate free 125I-labeled triiodothyronine from that bound to thyroxine-binding globulin. The techniques are laborious, time consuming, and not readily adaptable to total automation. In the assay we describe, triiodothyronine antibody, immobilized on the walls of polypropylene test tubes, is used as the bound-free separating agent in the evaluation of degree of unsaturation of thyroxine-binding globulin. The assay is simplified to four steps; washing, centrifugation, and use of columns are eliminated; and the procedure is readily automatable with existing pipetting equipment. Correlation with existing methods is excellent.     

Aging and presbycusis: Effects on 2-deoxy-d-glucose uptake in the mouse auditory brain stem in quiet

Autoradiography was used to assess the incorporation of [2-¹⁴C]deoxy-d-glucose by the auditory brain stem of young and aging mice of the strain (which demonstrates progressive chronic sensorineural hearing loss) and the CBA strain (which maintains good hearing until late in life). Animals were injected with labeled 2-deoxyglucose and placed in quiet for 45 min; brain stem sections were prepared for autoradiography. The amounts of 2-deoxyglucose incorporated into the anterior ventral cochlear nucleus (AVCN), inferior colliculus (IC), and trigeminal nerve (TN) were densitometrically analyzed. Within each subject, the densities of the three structures were statistically compared. In every mouse, inferior colliculus density was greater than that of the anterior ventral cochlear nucleus, which was greater than trigeminal nerve density. To compare subject groups, relative densities (inferior colliculus and anterior ventral cochlear nucleus re: trigeminal nerve) were used; no significant differences were found between groups. Thus, aging, with or without severe loss of hearing, is not associated with altered incorporation of 2-deoxyglucose (and presumably glucose) in quiet.     

Noncosmetic applications of liposuction

Noncosmetic applications of liposuction have continued to appear since its introduction into the United States in 1982. Although the most common use is in removing lipomas, liposuction has also been used for benign symmetric lipomatosis, flap undermining, flap defatting, gynecomastia, pseudogynecomastia, breast reduction, buffalo hump, hypertrophic insulin lipodystrophy, lymphedema, evacuating hematomas, emergency neck defatting for airway restoration, and axillary hyperhidrosis. Other uses remain to be discovered.