Human adrenoceptor system response to the development of high altitude pulmonary arterial hypertension.

High-altitude pulmonary arterial hypertension affects people with a long-term residence at altitudes over 2500 m above the sea level and is characterized by elevated pulmonary artery pressure (over 35/15 mmHg). In order to assess the role of beta-adrenoreceptors in the development of high-altitude pulmonary arterial hypertension, we studied the beta-adrenoreceptor density on mononuclear leukocytes in Kirghiz male natives of Eastern Pamir (3600-4200 m above sea level) with the diagnosis of high-altitude pulmonary arterial hypertension, and in healthy men. It was shown that patients with signs of right ventricular hypertrophy (RVH) of the second and third grade have beta-adrenoreceptor density 4.5 times lower than control (2.27 +/- 0.22 vs. 9.85 +/- 1.28 fmol/10(6) cells). Values of Kd also proved to be lower, by 2.5 times (0.57 +/- 0.14 vs. 1.44 +/- 0.18 nM). Stimulation of adenylate cyclase by isoproterenol and other beta-agonists was lower in patients than in controls (+33% and +120%, respectively). These results demonstrate that the desensitization of beta-adrenoreceptors is present in patients with high-altitude pulmonary arterial hypertension associated with severe right ventricular hypertrophy. Patients with pulmonary arterial hypertension due to mitral stenosis do not have any signs of beta-adrenoreceptor desensitization associated with high plasma levels of catecholamines.

Persistent cognitive impairment in climbers after repeated exposure to extreme altitude.

We performed neuropsychological testing in eight world class climbers who had reached summits higher than 8,500 meters without supplementary oxygen. Five had mildly impaired concentration, short-term memory, and ability to shift concepts and control errors. There were no defects in perception or other cognitive activities. The pattern of impairment suggests malfunctioning of bifronto-temporo-limbic structures. Repeated extreme-altitude exposure can cause mild but persistent cognitive impairment.

The risk factors for ischemic heart disease in Tibetan highlanders.

The risk factors for ischemic heart disease (IHD) in 35 Tibetan highlanders were investigated and compared with those in 30 age- and sex-matched healthy Japanese controls. Although Tibetans had remarkably high hematocrit values, and a decrease of eicosapentaenoic acid in both serum total lipids and serum phospholipid (PL) possibly due to their diet, they were considered to have a low incidence of IHD from our door-to-door study. These positive risk factors are likely counteracted by other negative risk factors as follows; Tibetans rarely exhibited systolic hypertension, and had lower levels of serum cholesterol and serum apolipoprotein (apo) B, and apo B/apo A-I ratio. In addition, Tibetan highlanders showed a decreased level of palmitic acid and an increased level of linoleic acid in serum PL which may protect against atherosclerosis.

Hydration and tissue solid content of the lean body on prolonged exposure to altitude.

Using densitometric, hydrometric and anthropometric techniques, body fat, tissue solids, water and mineral content were quantitatively measured on two groups each of 26 young and healthy Indian soldiers of mixed ethnic composition. The experimental group was exposed to 3500 m altitude for 2 years and the experiments were carried out after 48 h and 3 weeks rehabilitation in Delhi (300 m). The control group was never exposed to high altidues. Inspite of the experimental group being fed with superior rations at high altitude, this group showed significantly hyperhydrated lean body with reduced tissue solids in comparison to the control group which was fed with identical rations in Delhi. The calculated mean density of the fat free body had declined to 0.092 x 10(3) kg/m3. The 3 week stay at low altitude had little influence on body composition. Hyper-hydration, with reduced tissue solids, would cause reduction in the density of fat free body, and would thus interfere with the estimates of total body fat based on densitometric procedures alone. In the hyperhydrated state, Siri's formula overestimated fat by 22.8% of the true value.

Ecocardiografia modo "M" y bidimensional en cardiopatias congenitas en la altura (3.500 m) / Echocardiography mode \"M\" and bidimensional in heart defects, congenital in height (3.500 m)

Para evaluar la experiencia, alcances y limitaciones de la ecocardiografia en la valoracion de las cardiopatias congenitas, se reviso la casuistica de los ultimos 5 anos (1982-87) en el IBBA. De un total de 1736 ecocardiografias efectuadas 137 correspondieron a pacientes con diagnostico clinico de cardiopatia congenita. Grupo I (menores de 15 anos) 102 pacientes con cardiopatia congenita siendo la mas frecuentes CIV-CIA-PCA entre las cardiopatias acianoticas y la enfermedad de Ebstein(13 casos -76%). Grupo II (mayores de 15 años) 35 pacientes con cardiopatias congenitas siendo la mas frecuente la CIA (22%) entre las acianoticas y la enfermedad de Ebstein (8%) entre las cianoticas. Se discuten las aportaciones y las limitaciones que la ecocardiografia modo "M" presenta en la evaluacion de las alteraciones anatomicas de las cardiopatias congenitas asi como las ventajas sobre la misma de la acocardiografia bidimensional. Se analizan los hallazgos ecocardiograficos en las cardiopatias congenitas mas frecuentesl. Se concluye que la ecocardiografia constituye un adelanto significativo en la evaluacion y diagnostico de las cardiopatias.

Psychopathology in mountaineering--mental disturbances under high-altitude stress.

In the years 1960-1985 psychiatric and psychological research was conducted among a group of 80 Polish alpinists. Experimental research was conducted during the expeditions to the Hindu Kush mountains and to the Andes (1971, 1973-74, 1979, 1985). The aim of the research was to describe the personality of the alpinists, their motivation, as well as mental disturbances caused by staying at high altitudes. On the basis of an interview and the Cattell personality questionnaire, two types of personality were distinguished: the schizoid-psychasthenic type (53 persons, i.e. 66%) and the asthenic-neurotic type (23 persons, i.e. 30%). As regards the motivation for mountain climbing, situational and personality factors were described, among them, the need to experience "powerful situations" and compensating for an inferiority complex. A so called integrational fear which mobilizes the psychophysical capabilities to overcome the hardships of the climb, was described as characteristic of the alpinists. Depending on the altitude and the duration of one's stay at it, the mental disturbances, in most cases took on the form of the neurasthenic syndrome (asthenic or sthenic) at low altitudes (3000-4000 m), the cyclothymic syndrome at medium altitudes (4000-5000 m), and the acute organic brain syndrome at high altitudes (above 7000 m). In 24 (35%) cases, there occurred psychotic disturbances with profound disturbances of consciousness and orientation. These states were accompanied by symptoms of high-altitude deterioration with a break-down in the physical condition, disturbances in the hydro-electrolyte equilibrium, and a considerable loss of bodily weight.(ABSTRACT TRUNCATED AT 250 WORDS)

Estudios en recién nacidos de gestantes añosas de Cerro de Pasco (4,340 m.) / Newborn infants from aged pregnant women of Cerro de Pasco (4,340 m.)

Se han estudiado los partos ocurridos en madres mayores de 35 años atendidos entre 1982 y 1985 en Cerro de Pasco (4340m) cuyos datos son comparados con un número similar de partos ocurridos en madres menores de 35 años. Se encuentra que la edad materna tardía produce un mayor número de óbitos fetales masculinos que en el grupo control y que en RN mujeres de madres añosas. La tasa de RNBP, prematuridad y asfixia neonatal es alta en Cerro de Pasco comparado a lo observado a nivel del mar por otros autores

Cerebral thrombosis at altitude: its pathogenesis and the problems of prevention and treatment.

In analyzing cerebral thrombosis at altitude--own case and in the literature--we anatomically confirmed that cerebral thrombi in mountain sickness were all of venous origin. All climbers went higher than 5,000 m and most stayed in that altitude longer than 3 weeks. Hemoconcentration was confirmed in two cases, including our own patient. It was suspected that hemoconcentration resulting from secondary polycythemia and dehydration at altitude, as well as cerebral circulatory disturbance produced by high-altitude cerebral edema, played a major role in the development of cerebral thrombosis. The problems of prevention and treatment of cerebral thrombosis at altitude are discussed.

Myocardial hypertrophy in rats exposed to simulated high altitude.

Myocardial hypertrophy in Sprague-Dawley adult rats exposed to hypobaric hypoxia (0.40 atmosphere of air/18 h daily for 7 days) in a hypobaric chamber was investigated. Changes in the myocardial mass were evaluated on the basis of the dry heart weight and expressed as mg/100 g of total body weight (mean +/- SEM). Data are presented indicating that: chronic hypobaric hypoxia causes a significant degree of myocardial hypertrophy in rats; hypertrophic process involves both ventricles (the right more than the left); removal of the hypoxic stimulus leads to the disappearance of hypertrophy when evaluated as an increase in dry heart weight; hypoxia affects the synthesis of a significant amount of connective tissue in the left ventricle, which is not exposed to pressure load. The rôle of neurohumoral factors (i.e., adrenergic stimulation and catecholamines) in the development of the ventricular hypertrophy is suggested.

[Non-cardiac pulmonary edema: an enigma today]. / Edema polmonare non cardiaco: enigma di attualità.

Pulmonary oedema is caused by an excessive accumulation of interstitial fluid in the lungs: in the case of left ventricular failure, oedema arises due to an increase in capillary hydrostatic pressure. Non-cardiac oedema, on the other hand, is brought about by a change in alveolar capillary membrane permeability. Although the causes are different, namely respiratory distress syndrome in adults, altitude-induced pulmonary oedema, oxygen toxicity, medication, metabolic changes, etc., the result is the same, i.e. damage to the alveolar capillary membrane. This damage appears to be brought about by two factors: complement activation and damage to the blood clotting mechanism. The difference between cardiac and non-cardiac pulmonary oedema is difficult to gauge. If pulmonary cone pressure is normal or low, and if the oedematous fluid/plasma protein ratio is greater than 0.7, the oedema is non-cardiac in origin. Treatment is carried out with the aim of repairing the alveolar capillary membrane and preventing extension of the damage. Respiratory insufficiency is treated by a mechanical respirator, applying positive pressure at the end of expiration. Fluid administration is adjusted according to pulmonary cone pressure levels. Opinions are still divided over whether to administer crystalline or colloidal solutions, steroids or protease inhibitors.

Diethylcarbamazine inhibits acute and chronic hypoxic pulmonary hypertension in awake rats.

Leukotriene inhibitors preferentially inhibit the acute pressor response to hypoxia in isolated rat lungs. If leukotrienes are important in hypoxic pulmonary vasoconstriction, then inhibition of their synthesis could prevent the development of chronic hypoxic pulmonary hypertension. We found that diethylcarbamazine (DEC), a leukotriene synthesis blocker, reversibly inhibited acute hypoxic pulmonary vasoconstriction in the awake rat. Rats exposed to chronic hypobaric hypoxia showed pulmonary hypertension and the production of a slow-reacting substance compared with low altitude control rats. The higher of 2 doses of DEC blocked the pulmonary hypertension and the production of slow-reacting substance in all of the hypoxic rats treated. The lower dose of DEC attenuated the pulmonary hypertension in only some of the rats. Changes in weight gain, hematocrit, or generation of prostacyclin did not explain the prevention of the pulmonary hypertension by DEC. We conclude that diethylcarbamazine inhibits acute and chronic pulmonary hypertension in the intact rat.

Hormonal disturbances of fluid-electrolyte metabolism under altitude exposure in man.

Early alterations in fluid, electrolytes, and their regulating hormones were investigated in men exposed to 6,000 m simulated altitude (2 h-ascent, 2 h-sojourn, 2 h-return). Hematocrit and serum protein rose with elevated serum osmolality and reduced urine flow upon arrival at 6,000 m, suggesting decreased plasma volume probably due to hypotonic fluid shift to intracellular spaces. Serum K declined reflecting respiratory alkalosis. The exposure raised plasma antidiuretic hormone (ADH), plasma renin activity (PRA), serum cortisol and aldosterone. Increases both in ADH and aldosterone showed close correlations with that in cortisol, suggesting that ADH may be elevated by hypoxic stress in addition to elevated serum osmolality and decreased plasma volume, and that increased secretion of adrenocorticotropin may be the main cause of increased aldosterone, though PRA involvement cannot be excluded. These rises in ADH and aldosterone may act to retain body water, and the latter may exaggerate alkalosis; thus, these hormonal changes may be related to acute mountain sickness.