Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0038454 (stroke)
 147,016 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The mechanism of elevation of left ventricular end-diastolic pressure during acute global ischemia was evaluated by examiniation of the relative contributions of a decrease in contractility and an alteration of the pressure-volume relationship. The external circumference (mercury-in-silastic gauge) pressure relationship, as an index of the pressure-volume relationship, was studied in beta adrenergic and ganglionic blocked, open chest dogs on right heart bypass at constant heart rate ane aortic pressure. Ischemia of one and two hours' duration was produced by reducing total coronary blood flow in cannulated left and right coronary arteries until left ventricular end-diastolic pressure rose significantly. At a constant stroke work, left ventricular end-diastolic pressure rose from 5.0 +/- 0.5 to 15.0 +/- 0.5 cm H2O in the experiments of one hour of ischemia, and from 7.0 +/- 1.0 to 17.0 +/- 1.0 cm H2O in experiments of two hours of ischemia. Ischemia was followed by one hour of restoration of coronary blood flow. Ischemia produced a marked depression of ventricular function: stroke work, considered at a left ventricular end-diastolic pressure of 15 cm H2O, decreased from 21.0 +/- 3.0 to 3.5 +/- 0.5 gm-m, and from 15.0 +/- 2.0 to 2.5 +/- 0.5 gm-m, in the experiments of one and two hours, respectively. Neither ischemia nor reflow changed the pressure-volume relationship. Thus, the elevation of left ventricular end-diastolic pressure during ischemia in an otherwise normal canine myocardium is due to a decrease in systolic performance of the heart rather than to an alteration of the pressure-volume relationship.
 ...
PMID:Left ventricular end-diastolic pressure volume relationships with experimental acute global ischemia. 108 86

A description is presented of a new and simple procedure for ventricular volume determination by means of pressure fixation of the heart and preparation of plastic molds of the ventricles which can be used to displace water in a graduated cylinder to determine the volume of the mold. Correlations between postmortem ventricular volume as measured by this method and antemortem stroke volume or clinical cardiac status indicate that a large left ventricular volume is often correlated with a low cardiac output and cardiogenic shock.
 ...
PMID:A new method for determination of postmortem left ventricular volumes: clinico-pathologic correlations. 111 71

Although the environmental stresses to which man is subjected on the ground are less than those commonly encountered in aviation or under water, they may still exceed an individual's powers of adaptation. Extremes of temperature, commonly encountered in the Arctic or the tropics, may occur in regions of normally temperate climate and lead to failure of temperature regulation, resulting in hypothermia, frostbite, heat exhaustion, or heat stroke. High mountains impose additional hazards due to high winds and lack of oxygen, and deep mines are dangerous work-places because of high temperature and humidity. Some physiological acclimatization occurs in extreme natural environments and the dangers may be reduced by appropriate clothing, diet and behaviour.
 ...
PMID:Adaptation and failure of adaptation to extreme natural environments. 113 66

Using a "slit camera" recording technique, we have examined the effects of local laser irradiation of cilia of the gill epithelium of Mytilus edulis. The laser produces a lesion which interrupts epithelial integrity. In artificial sea water that contains high K+ or is effectively Ca++ free, metachronism of the lateral cilia continues to either side of the lesion with only minor perturbations in frequency synchronization and wave velocity, such as would be expected if metachronal wave coordination is mechanical. However, in normal sea water and other appropriate ionic conditions (i.e., where Ca++ concentration is elevated), in addition to local damage, the laser induces distinct arrest responses of the lateral cilia. Arrest is not mechanically coordinated, since cilia stop in sequence depending on stroke position as well as distance from the lesion. The velocity of arrest under standard conditions is about 3 mm/s, several orders of magnitude faster than spreading velocities associated with diffusion of materials from the injured region. Two responses can be distinguished on the basis of the kinetics of recovery of the arrested regions. These are (a) a nondecremental response that resembles spontaneous ciliary stoppage in the gills, and (b) a decremental response, where arrest nearer the stimulus point is much longer lasting. The slower recovery is often periodic, with a step size approximating lateral cell length. Arrest responses with altered kinetics also occur in laterofrontal cilia. The responses of Mytilus lateral cilia resemble the spreading ciliary arrest seen in Elliptio and arrest induced by electrical and other stimuli, and the decremental response may depend upon electrotonic spread of potential change produced at the stimulus site. If this were coupled to transient changes in Ca++ permeability of the cell membrane, a local rise in Ca++ concentration might inhibit ciliary beat at a sensitive point in the stroke cycle to produce the observed arrest.
 ...
PMID:Laser-induced spreading arrest of Mytilus gill cilia. 114 83

Cold water is known to facilitate the drowning process. To gather information on the possible relationship between ventilation and cold stimuli, measurements of inspired and expired breath by breath ventilation and alveolar PCO2 were made on 8 male subjects suddenly immersed in both cold (11 degrees C) and warm water (28 degrees C). The mean ventilation for all subjects for the 1st three breaths following cold water immersion was 94.5, 71.3 and 94.6 L/min (BTPS) as compared to 60.0, 36.2 and 38.5 L/min (BTPS) for warm water immersion. Alveolar CO2 fell dramatically in cold water from a pre-immersion mean value of 36.4 torr to 23.9 torr, whereas there was only a change associated with the first few breaths following immersion in warm water. In prolonged cold exposure, ventilation was still markedly above that observed in warm water after 5 min. There was no relationship between skin fold thickness and ventilatory response over the period studied. A large increase in ventilations is likely to result in inefficient swim stroke mechanics. This, combined with a high probability of inspiration of water, may contribute to death as a consequence of cold water exposure.
 ...
PMID:Sudden cold water immersion. 114 45

The offspring of male stroke-prone SHR, 80 in total, were divided into treated and nontreated groups at the age of 30 to 45 days. The former groups were treated with alpha-methyl dopa (2 g/l in the drinking water), or L-dopa (2 g/l) with or without peripheral decarboxylase inhibitor (MK-486, 1-3 g/l) or apresoline (0.08 g/l) thereafter till they died a natural death during 1 and a half year observation period. So far as hypertension was controlled under about 210 mmHg, no stroke was observed, while nontreated group developed cerebrovascular lesions spontaneously in about 80 per cent. This study experimentally confirmed the importance of blood pressure control for the prevention of stroke.
 ...
PMID:Experimental studies on the pathogenesis and prophylaxis of stroke in stroke-prone spontaneously hypertensive rats (SHR). (2) Prophylactic effect of moderate control of blood pressure on stroke. 115 94

The effects of moderate arterial hyperosmolality (+20 mOsm/kg H2O), produced by short term intravenous hypertonic infusion, on vascular resistance in skin, skeletal muscle, intestine, and kidney were analyzed in the anesthetized cat. Vascular resistance decreased in all four regions in response to the hypertonicity both before and after regional sympathectomy and the effects were not significantly altered by beta-adreno-ceptor blockade. Arterial blood pressure rose during the hypertonic infusion despite the decreased vascular resistance and an unchanged heart rate, indicating an increased stroke volume and cardiac output. Similar increases of arterial osmolality are known to occur in heavy exercise and in hemorrhage. The present results may therefore suggest that blood borne hyperosmolality is a factor which can contribute to the overall cardiovascular adjustments in these situations.
 ...
PMID:Circulatory effects evoded by 'physiological' increases of arterial osmolality. 115 24

Changes in oxygen uptake, cardiac output, heart rate, stroke volume, central blood volume, arteriovenous oxygen difference, aortic, pulmonary arterial, and right atrial blood pressure, systemic vascular resistance, hematocrit, circulating plasma volume, urine flow, fractional sodium excretion, and free water clearance were studied in eight healthy volunteers in stable water diuresis, exposed to cold by means of air at +15 degrees C and at a speed of 0.5 m/sec. A decrease in circulating plasma volume and systemic vascular resistance was found during cold stress. Mean aortic blood pressure, sodium excretion, cardiac output, oxygen uptake, arteriovenous oxygen difference, and hematocrit increased. No changes in urine flow or in clearance of free water could be demonstrated. Heart rate, stroke volume, and central blood volume showed significant increases in cold. The results are interpreted to suggest that exposure to cold raises the arterial blood pressure by an increase in cardiac output, thereby increasing capillary hydrostatic pressure in certain vascular areas, including the renal vascular bed. This negatively affects capillary reabsorption processes in the kidney, causing a reduction in tubular sodium reabsorption, thus giving rise to a natriuresis. In other areas it seems to cause a shift of fluid towards the intersitial space.
 ...
PMID:Cardiovascular and renal responses to acute cold exposure in water-loaded man. 118 88

Lactate and pyruvate concentrations and acid-base balance in cerebrospinal fluid (CSF) and arterial blood were determined in patients with intracranial hemorrhages (28 subarachnoid hemorrhages and 15 intracerebral hemorrhages). A greater increase in CSF lactate and lactate-pyruvate ratio (L/P ratio) was observed in patients with impairment of consciousness, focal neurological deficits, poor prognosis, or CSF pressures higher than 300 mm H2O. A combination of CSF lactate greater than 2.5 mM per liter, L/P ration above 20, bicarbonate less than 20.4 mEq per liter, pH below 7.276, or arterial PCO2 below 31.5 mm Hg seems to indicate poor prognosis from intracranial hemorrhage. The mechanism of hyperventilation in acute cerebrovascular diseases and of CSF pH regulation in acid-base disturbances was also discussed.
Stroke
PMID:Cerebrospinal fluid and arterial lactate, pyruvate and acid-base balance in patients with intracranial hemorrhages. 119 37

A morphometric method was presented to estimate brain swelling or atrophy from the geometric characteristics of the pontine cross section. The ratio of the area (A) to the perimeter squared (L2) was termed "area factor" (f) and used as a factor indicating circularity. Normal standards for the net cross-sectional area (Ap) and the area factor (f) of the pons measured on paraffin sections were 3.43 approximately 4.87 cm2 and 0.0684 approximately 0.0740, respectively. Values exceeding these ranges suggested brain edema. The pontine area factors (f) of the control cases under 60 years of age were less spread out than Ap, whereas they exhibited larger individual variations over that age presumably as a result of varying involution of the brain. A close correlation was found between Ap and water content of the cerebral white matter, except in pontine hemorrhage. The correlation was particularly marked in the group of cerebral diseases other than stroke. The longitudinal length of the basis pontis (lp) was essentially the same in the normal brain and even in the stoke group excluding pontine and cerebellar hemorrhage. In severe brain swelling the pontine longitudinal length was rather reduced.
 ...
PMID:Morphometric estimation of brain swelling and atrophy. 120 54


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>