Stimulation of serum cortisol and prolactin secretion in humans by MK-212, a centrally active serotonin agonist

The effects of MK-212 [6-chloro-2-(1-piperazinyl)-pyrazine] (10, 20, and 40 mg, orally), a centrally acting serotonin (5-HT) receptor agonist and placebo, on serum cortisol, prolactin, and growth hormone levels were studied in eight healthy men over 3-hr. MK-212 produced a dose-related increase in serum cortisol levels, with the 20- and 40-mg doses producing significant elevations. Serum prolactin levels were significantly elevated only by the 40-mg dose. Serum GH levels were not significantly modified by any dose of MK-212. The cortisol and prolactin responses to the 40-mg dose of MK-212 were positively correlated (rho = + 0.85, p less than 0.02). MK-212 was generally well tolerated by the subjects. Headache and nausea were observed at the higher doses, but did not appear to be related to the increase in serum cortisol and prolactin levels. MK-212 may stimulate the secretion of cortisol and prolactin in humans via a serotonin (5-HT2) receptor mechanism and may be a valuable tool with which to study 5-HT receptor sensitivity in humans.     

Group B streptococcal arthritis in adults

Group B Streptococcal arthritis in adults is uncommon. This report describes seven cases seen at these institutions over the past five years and reviews the previous 17 documented cases. Of seven adults, three were diabetics, three had prosthetic hips, and one had undergone splenectomy. Six had undergone no prior dental, genitourinary, or gastrointestinal procedures. The most common clinical presentation was fever and acute joint pain. Five patients had monoarticular arthritis; two had multiple joint involvement. Underlying joint abnormalities included osteoarthritis (two), prosthetic hip (three), and neuropathic joint (one). Bacteremia was documented in three and suspected in the remaining four patients, often without a primary source. Therapy included parenteral antibiotics, usually penicillin G, and drainage of the involved joint. Two of three patients with prosthetic implants required Girdlestone procedures; the third was apparently cured. The three diabetic patients died, one with resolution of group B Streptococcal arthritis. The seventh patient was cured. Group B Streptococcal arthritis is a serious infection in adults with diabetes and late prosthetic hip infections.     

Discrimination learning requiring different memory components in rats: age and neurochemical comparisons

The performances of young (8-9 months) and aged (22-24 months) male ACI rats were compared in a T-maze requiring two discriminations, each of which placed different demands on memory processing. A spatial discrimination in the stem of the T-maze required long-term reference memory; a discrete-trial, alternation discrimination in the arms of the T-maze required working memory. Following acquisition training in one maze, rats were also trained in a second maze at a different location in the room. The correct response in the stem of this maze was opposite to that in the first maze. In two experiments with slightly different pretraining procedures, similar results demonstrated that aged rats made more errors in all phases of maze training than did their young counterparts. The results suggest that all components of memory processing were affected equivalently because the age-related impairment was not selectively greater in any component of the task. In a third experiment, aged rats were unimpaired in the ability to perform in a T-maze task involving a brightness discrimination with intramaze cues. This result suggests that the age-related impairment in the two-component T-maze task was restricted to the cognitive demands of the task. Neurochemical analyses were performed to determine whether regional neurotransmitter synthetic enzyme activities could be used to identify neurochemical systems associated with performance in these tasks and with any age-related impairments observed. Choline acetyltransferase and glutamic acid decarboxylase were assayed as markers for cholinergic and GABAergic systems, respectively, in the hippocampi and the following cortical regions: frontal, sensorimotor, auditory, cingulate, occipital, and pyriform-perirhinal. A slight (8%) but significant age-related decline was observed in the activity of glutamic acid decarboxylase but not of choline acetyltransferase. Although the correlation between maze performance and regional enzyme activities generally supported several previous observations, the only significant correlation to emerge was between working memory performance and glutamic acid decarboxylase activity in the cingulate cortex.     

Measures to decrease the risk of acquired immunodeficiency syndrome transmission by blood transfusion. Evidence of volunteer blood donor cooperation

We studied whether volunteers giving blood to the Greater New York Blood Program (GNYBP) cooperated with procedures implementing public health recommendations intended to decrease the risk of acquired immunodeficiency syndrome (AIDS) transmission by blood transfusion. Predonation medical screening was expanded to exclude donors who might be ill with AIDS. To exclude possible asymptomatic carriers of the disease, members of groups at increased risk of AIDS were asked either not to give blood or to give it for laboratory studies. A confidential questionnaire, administered to all donors after medical screening, provided the vehicle for donors to advise the GNYBP whether their donation was for laboratory studies or for patient transfusion. We found that the number of male donors decreased; AIDS-related questions in medical history led to a 2 percent increase in donor rejections; 97 percent of donors said their blood could be used for transfusions; 1.4 percent said their blood could be used for laboratory studies only; and 1.6 percent did not respond. Only units designated for transfusion were released to hospitals. People who indicated that their donation was for laboratory studies had a higher prevalence of markers for hepatitis B virus and of antibodies to cytomegalovirus. White cell counts and helper/suppressor T lymphocyte ratios were not significantly different in the two groups. We conclude that volunteer donors have cooperated with the established procedures. None of the laboratory assays identified blood units donated by individuals who, based on information about AIDS high-risk groups, designated their donation for laboratory studies.     

Mounting and calibration of stairs on piezoelectric force platforms

To calculate the centre of pressure using piezoelectric force plates mounted on pads, no net tensile stresses may be imposed on the surface of the plate. This condition is violated when stairs are attached to the plates, unless the plates are preloaded. Typical shear forces encountered when climbing stairs were used to determine required preloads of approximately 16.4 N/cm step height. Vertical and horizontal loads were applied at known locations on the steps, and points of application were calculated. Deviations were within ± 3 mm. The effect of point of application inaccuracy on calculated joint moments is considerable. A 2 cm medial shift in the point of application resulted in calculated peak knee abduction/adduction moment errors of 35%.     

Use of memory meters to measure reliability of self blood glucose monitoring

Glucose reflectance meters equipped with memories were used in 21 insulin-dependent diabetic patients to assess reliability of self blood glucose monitoring records. Results reported in logbooks showed widespread discrepancies when compared with corresponding meter-held records. Discrepancy rates of at least one in five were observed in 11 patients. Unreliable reporting was usually recognized by clinical staff, and associated with high glycosylated haemoglobin levels and poor technique in measuring blood glucose at home.     

Various toxic effects of nitrates and nitrites]

The main features of the long-term toxicity of nitrates and/or nitrites in man and experimental animals are reviewed; the possible formation of carcinogenic nitrosamines is dealt with in another paper of this series. It appears that the allowable daily intake of nitrates and nitrites for the healthy adult man has been evaluated chiefly from the no-effect levels in rats. First, the no-effect levels in rats are questionable, since some experiments have pointed out adverse effects of nitrates and nitrites with dosages near, or lower than, the so-called no-effect levels. Second, there is a risk that the allowable daily intake is outpassed in the diet of a man. Third, nutritional conditions, such as the vitamin A or C, or the iodine content of the diet, as well as other factors which are discussed, might alter theno-effect levels. From the cell metabolism viewpoint, nitrites are inhibitors of oxidative phosphorylation and of microsomal enzymes. Our present lack of knowledge does not yet allow us to explain the long-term toxicity of nitrates and nitrites in terms of cell metabolic disturbances.