Learning and memory function in men with untreated blood pressure elevation

Learning and memory processes were compared in 20 men with untreated blood pressure elevation and 20 normotensive control subjects matched for age, education, and average alcohol consumption. Subjects were identified from a larger sample of 469 factory workers who had participated in an epidemiologic investigation. Three measures (e.g., Symbol-Digit Learning Test [Ryan & Butters, 1980] and Visual Reproductions-Immediate and Delayed Recall [Wechsler, 1945] ) from a previously administered test battery were chosen for comparison on the basis of statistical power calculations. Results indicate that relative to normotensive control subjects, men with elevated blood pressure performed more poorly on all three tests. These results are independent of other known influences on neuropsychological performance and are likely a consequence of elevated blood pressure.     

Cerebral vascular effects of angiotensin II: new insights from genetic models.

Very little is known regarding the mechanisms of action of angiotensin II (Ang II) or the consequences of Ang II-dependent hypertension in the cerebral circulation. We tested the hypothesis that Ang II produces constriction of cerebral arteries that is mediated by activation of AT1A receptors and Rho-kinase. Basilar arteries (baseline diameter approximately 130 microm) from mice were isolated, cannulated and pressurized to measure the vessel diameter. Angiotensin II was a potent constrictor in arteries from male, but not female, mice. Vasoconstriction in response to Ang II was prevented by an inhibitor of Rho-kinase (Y-27632) in control mice, and was reduced by approximately 85% in mice deficient in expression of AT1A receptors. We also examined the chronic effects of Ang II using a model of Ang II-dependent hypertension, mice which overexpress human renin (R+) and angiotensinogen (A+). Responses to the endothelium-dependent agonist acetylcholine were markedly impaired in R+A+ mice (P<0.01) compared with controls, but were restored to normal by a superoxide scavenger (PEG-SOD). A-23187 (another endothelium-dependent agonist) produced vasodilation in control mice, but no response or vasoconstriction in R+A+ mice. In contrast, dilation of the basilar artery in response to a NO donor (NONOate) was similar in R+A+ mice and controls. Thus, Ang II produces potent constriction of cerebral arteries via activation of AT1A receptors and Rho-kinase. There are marked gender differences in cerebral vascular responses to Ang II. Endothelial function is greatly impaired in a genetic model of Ang II-dependent hypertension via a mechanism that involves superoxide.     

Pathogenesis of postoperative hyponatraemia following correction of scoliosis in children

Eight paediatric patients undergoing major surgery for correction of scoliosis who were treated postoperatively with hypotonic saline and 5% dextrose have been studied. Plasma sodium, renin and aldosterone, and urine volume, sodium and osmolality were measured. These patients had an impaired ability to excrete a sodium-free water load. In the first 60 h urine volume remained reduced, while in the first 36 h urine sodium remained concurrently high. If the first 36 h postoperation are considered, the sodium-free water given was quantitatively retained and the serum sodium at 36 h was significantly correlated with the amount of free water given (P less than 0.01). To minimize postoperative hyponatraemia and the associated shift of water into the brain causing cerebral oedema, it is recommended that no more than 50 ml/kg sodium-free water be given until urine sodium falls and volume increases.     

A sports medicine clinic in the community.

We report the attempt to set up a mini sports medicine clinic in a health centre resourced by a Department of Community Medicine. The type of problems seen are similar to those reported by other clinics. On the results of this pilot project, we believe it would be possible to establish similar clinics in health centres elsewhere in the United Kingdom. The National Health Service resources required are minimal, but the benefits to local communities are considerable.     

High tech home care: a look at a success story.

The expansion of technology has allowed patients to receive intravenous therapy at home. This case study discusses the problems of a patient with diabetes mellitus and malignant otitis externa. This patient received intravenous therapy for the last 3 years of his life. In spite of several hospitalizations, he was able to return and remain home until his death. Management of the patient's discharge and home care seemed to be a major factor in his ability to remain in the community.     

Call patterns and basilar papilla tuning in cricket frogs. I. Differences among populations and between sexes.

Male cricket frogs (Acris crepitans) produce a broad-band, high frequency advertisement call with a single spectral peak (the dominant frequency). We measured the dominant frequencies of male calls from six populations in central Texas and one from Indiana and compared them to the tuning of basilar papilla afferents in males and females. Averaging over all populations, mean call dominant frequency was 3.69 kHz, mean male basilar papilla tuning was 3.63 kHz, and mean female basilar papilla tuning was 3.17 kHz. Among populations, mean dominant frequency varied from 3.56 kHz to 3.82 kHz. Dominant frequencies were slightly higher in the more eastern Texas populations occupying pine forest habitats than in the more western populations occupying open grassland habitats. Changes in dominant frequency in a population coincided with changes in tuning of both male and female basilar papillae. Furthermore, within populations females were tuned on average lower than males and lower than the mean dominant frequency of calls in their own population. We suggest that the coincident changes in calls and basilar papilla tuning plus the sexual difference in tuning indicate that female mate choice would be directed toward males from her home population with low frequency calls or toward males from foreign populations with average calls lower in frequency than those in her home population. This in turn suggests that any gene flow between populations would be biased from east to west and from forest to open habitats.     

Assessing Alzheimer severity with a global clinical scale.

Diagnosis of dementia needs to be complemented by precise determination of disease severity across the broad spectrum of disease progression. The Mini-Mental State Exam (MMS), the Activities-of-Daily-Living assessment (ADL) and the Clinical Dementia Rating scale (CDR) were modified for direct comparability and administered to 112 outpatients and 45 nursing home residents with a range of dementia severity from mild to profound. The scales showed the highest correlations for the probable Alzheimer's disease patient group (62) (Global Assessment of Dementia; GAD vs. ADL: r = 0.91; Extended Mini-Mental Assessment; EMA vs. GAD: r = 0.91; ADL vs. EMA: r = 0.86). For these patients, scores on the individual scales tended to be similar. Disparity among the three scores for individual cases was associated with the presence of comorbidities. The high correlations and correspondence among these scales demonstrate their reliability, validity, and utility in the assessment of dementia severity. The use of an average of these measures, with their increased precision, may give a more accurate indication of dementia severity over a broader range of impairment.     

Argon laser lesions of the retina; occurrence and origin of macrophages.

Macrophage infiltration is frequent in the early stages of various proliferative eye disorders, including subretinal neovascularization. In this study, we set out to establish the origin of macrophages found in an animal model of laser-induced subretinal neovascularization. One primate received several intravenous injections of a colloidal carbon suspension. We then applied standard argon laser lesions to the retina of both eyes, which were enucleated eight days later and sectioned serially for histological examination. A quantitative estimate of carbon-laden and non-laden leukocytes was made based on morphological criteria. Mononuclear leukocytes accumulated in the laser lesions and the percentage of carbon-laden mononuclear leukocytes in relation to the total leukocyte number was higher in the extravascular area of the laser sites than in the systemic circulation. These findings indicate that the majority of mononuclear leukocytes that accumulate at the sites of laser lesions are derived from the systemic circulation.