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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.

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.

Animals

Observer variations in the diagnosis of stroke. WHO collaborative study on the control of stroke in the community.

Validity and consistency of the diagnosis of stroke and its types were tested with 60 case reports including 15 diguised duplicates, drawn at random from community-based stroke registers. Seven European, 5 Japanese, and 5 other centers participated the test. The diagnosis of stroke as such (regardless of its type) seems to have been established accurately in all the 3 groups of centers; this leads to the conclusion that the incidence rates of stroke as registered in the participating centers were comparable. The diagnosis of the types of stroke was less reliable, since intra-and inter-observer bias was found in the diagnosis of the identical sample of test cases. In some European centers, the type of stroke was rarely determined, unless objective and definitive evidences were available. The Japanese centers appeared to have diagnosed the type of stroke in a relatively more uniform way between centers, however, the consistency of the diagnosis at separate times was lower. Subarachnoid hemorrhage, when diagnosed, was generally based on firmer gounds. These observations were confirmed in a small number of autopsy-verified cases. These varying diagnostic attitudes introduce false differences. Such "softness" of type-diagnosis must be borne in mind when comparison of type of stroke at different times or between populations is attempted.

Cerebral Hemorrhage

Relationships of stroke rate, distance per stroke, and velocity in competitive swimming.

Competitive swimmers were asked to swim at a constant velocity (v) for short distances. They wore a collar to which was attached a fine non-elastic steel wire. The wire passed over two wheels of a device attached to one end of the pool. One wheel generated an impulse for every cm of forward movement and another wheel produced an electrical signal which was directly proportional to V. Measurements of distance and time were begun at definable points in the stroke cycle and were discontinued at the end of a predetermined number of strokes. In all of the four competitive strokes, front and back crawl, butterfly, and breaststroke, the V increased as a result of increasing the stroke rate (S) and decreasing the distance per stroke (d/s). In the front crawl, the male and female swimmers who achieved the fastest V had the longest d/S at slow S. The faster male swimmers also had greater percent decrease of the d/S at their maximal V than did the less skilled persons. The back crawl was similar to the front crawl except that maximal S and V were less. Increases of V of the butterfly were related almost entirely to increases in S. Except at the highest V, d/S was decreased somewhat. In the breaststroke increased V was also associated with increasing S, but the d/S decreased much more than in the other stroke styles. Fluctuations of velocity during the stroke cycle were least in the front and back crawl (+/- 15--20%) and greatest in the butterfly and breaststroke (+ 45--50%). The results were compared to the S observed and the values for V and d/S calculated for a large group of swimmers competing in the 1976 U.S. Olympic Trials. The implications of the findings for coaching swimmers are discussed.

Biomechanical Phenomena

Pathogenetic similarity of strokes in stroke-prone spontaneously hypertensive rats and humans.

The predilection sites of cerebrovascular lesions (cerebral hemorrhage and/or softening) were studied in 1,278 stroke-prone spontaneously hypertensive rats (SHRSP). The precise supply to the main cerebral arteries was determined by trypan blue injections and microangiography. The three major territories were the anteromedial cortex, the occipital cortex, and the basal ganglia. A common angioarchitectural characteristic of these three areas was the blood supply through "recurrent branching" from the main stream. In the basal ganglia, where there is a preponderance of lesions, the arteries responsible for these lesions belonged to the lateral group of lenticulostriate arteries. The primary pre-stroke arterial lesions were further studied microangiographically in SHRSP killed at the time the initial symptoms of stroke were detected. These points were located at the "boundary zone" of the main cerebral arteries. Our findings indicated the importance of these two angioarchitectural minor loci as the basis for functional or organic circulatory disturbances that may cause stroke. Since these local factors of stroke are common in the cortex and basal ganglia of rats and basal ganglia of humans, these SHRSP are regarded as good pathogenetic models for studies on stroke in humans.

Animals

Studies on cerebrovascular stroke. III. Long-term prognosis and clinical findings in a follow-up study of a stroke material.

The present paper reports the third part of an investigation of first-time cerebrovascular strokes occurring in people under the age of 70. The long-term prognosis for 214 patients discharged alive from hospital after the acute phase of the stroke is presented. The clinical and laboratory findings for 114 patients alive at the time of a follow-up examination 32 months after the stroke are discussed. The long-term prognosis could be predicted best by a score, calculated from the neurological findings on admission after the acute stroke. Recurrence of stroke was associated with a very high mortality. Forty-five per cent of the patients who survived the first month had died by the time of follow-up. About 15% were able to return to normal life or go back to work. There was a trend among patients originally severely handicapped to improve their performance ability. Factors influencing the chances for rehabilitation are discussed. Among the survivors there was a strikingly high percentage of patients with overt diabetes or decreased glucose tolerance, of patients with arteriosclerotic heart disease and patients with elevated serum triglyceride levels. These findings are discussed.

Age Factors

Effects of chemical sympathectomy on hypertension and stroke in stroke-prone spontaneously hypertensive rats.

Neonates of male stroke-prone spontaneously hypertensive rats (SHRSP) were treated with 6-hydroxydopamine (6-OHDA) on two different schedules. Peripheral sympathectomy, which was evaluated by the pressor response to exogenous noradrenaline (NA) or by the decrease in NA content of the spleen, was more evident in the NB-8 group (treated on 8th and 15th day after birth) than in the NB-1 group (treated at 6, 24 and 72 h after birth). The reduction of the NA content in the cerebral cortex was more prominent in the NB-1 group than in the NB-8 group. The blood pressure from 7 to 23 weeks of age was lower in the treated groups: NB-8 less than NB-1 less than control. Therefore, the reduction of blood pressure in the treated groups could be related to the severity of peripheral sympathectomy. The incidence of sroke was also lower in the treated groups: 38, 11 and 0% in the control NB-1 and NB-8 groups, respectively. Loading with 1% NaCl solution from 11 weeks of age enhanced the rise in blood pressure and increased the incidence of stroke in each group of rats: 100, 20 and 40% in the control. NB-1 and NB-8 groups, respectively. However, the onset of stroke after exhibiting a severe hypertension (greater than 200 mmHg) was delayed in the treated groups. It seems that the activated tone in the peripheral sympathetic nerve is likely to participate in the development of spontaneous hypertension. In addition to the high blood pressure level, the activated tone of sympathetic nerve innervating the cerebral vasculature may be partly involved in the development of stroke in the new strain of the SHR rats, SHRSP.

Animals

Production of prostacyclin-like substance in stroke-prone and stroke-resistant spontaneously hypertensive rats.

Activities of aortae to produce prostaglandin (PG) I2-like substance in stroke-prone spontaneously hypertensive rats (SHRSP), stroke-resistant SHR (SHRSR) and normotensive control rats from the Wistar-Kyoto (WK) colony were compared. PGI2-like substance was produced by the incubation of the aortic ring in pH 9.0 borate-buffered saline and the amount produced was estimated by comparison of its anti-aggregatory activity with that produced by known amounts of the sodium salt of synthetic PGI2. Before the development of stroke, amounts of this substance generated in SHRSP and SHRSR were significantly higher than those in WK rats (p less than 0.01 and p less than 0.02, respectively). Remarkably reduced capacity to generate PGI2-like substance was observed in some SHRSP after the development of stroke.

Animals

Studies on cerebrovascular stroke. I. Epidemiology of first-time strokes in persons under 70 years of age.

The present investigation was carried out to study the incidence of new cerebrovascular strokes (cerebral haemorrhage, cerebral infarction and cerebral embolism) in people under the age of 70. SUCH INFORMATION HAS HITHERTO BEEN LACKING. The material comprises all cases from Uppsala county occurring between 1967 and 1971. The incidence was found to be 36/100,000 inhabitants. Of the total number of strokes, 25% were recurrences. During the period of study the incidence showed a moderate but significant decrease. It is assumed that this decrease is due to an extended and improved treatment of hypertension. It was observed that there were 6 females below 40 years of age. All had been on oral contraceptives at the time of the stroke. There was a high incidence of diabetes and symptoms of cardiovascular impairment (hypertension, transient ischaemic attack (TIA), cardiosclerotic disease) in the series. A high incidence of myocardial infarction was found among the parents of the cases of cerebral haemorrhage. A high incidence of strokes was found among the parents of those having cerebral infarctions.

Adult

Fluctuation of lipid peroxides and related enzyme activities at time of stroke in stroke-prone spontaneously hypertensive rats.

The levels of lipid peroxides, determined as thiobarbituric acid reactive substances (TBARS), and the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), were examined in the blood from stroke-prone spontaneously hypertensive rats (SHRSP), with and without cerebral lesions, and normotensive Wistar Kyoto (WK) rats. The levels of TBARS in the blood from healthy SHRSP were not significantly different from those of WK rats, while the values of SHRSP (male) with stroke were more than twice as high as those of healthy SHRSP. The activities of SOD and GSH-Px in stroke SHRSP were also statistically different from those of healthy SHRSP.

Animals

Prophylactic trials for stroke in stroke-prone SHR. (3) Amino acid analysis of various diets and their prophylactic effect.

This study confirmed again that high protein diet feeding decreased the incidence of stroke, and high fish protein diet did attenuate severe hypertension but high soybean protein diet did not affect the hypertension. Dietary amino acid analyses indicated that increases in total amino acids, essential amino acids and nonpolar amino acids but not acid or basic amino acids were significantly related to the reduction of stroke incidence. Among essential amino acids, lysine, threonine, isoleucine, and leucine contents were inversely related to stroke incidence, and methionine content was significantly related to the dietary antihypertensive effect of high protein diets. The prophylactic effect of high protein diets may be ascribed to some amino acid constituent.

Amino Acids

XIII. Cerebral circulation and metabolism in stroke. Cerebral circulation and metabolism in stroke study group.

An understanding of the cerebral circulation is so fundamental to comprehension of the pathogenesis of stroke that cerebral blood flow and metabolism merit review in this series of reports. The authors recognize that the research described here is very technical in nature and may appear to have little practical application to clinical medicine. Nevertheless, these matters are basic to the development of precise methods for the measurement of regional cerebral blood flow in man which could be used to monitor the therapy of stroke with greater success than is possible at present.

Brain

Report of Joint Committee for Stroke Resources. IV. Brain edema in stroke.

A classification of brain edema is provided as well as an extensive review of the animal models from which we have derived most of the basic information we have about the formation and resolution of edema. The clinical aspects of cerebral edema in stroke are discussed and also modern methods for identifying cerebral edema in the human. Attention is given to computed tomography and enhanced CT and advances in their application to this condition. Treatment of cerebral edema in the stroke patient using glycerol, dextran 40, mannitol, steroids, and other drugs is discussed and the need pointed out for controlled clinical trials of the therapeutic effectiveness of these agents.

Adrenal Cortex Hormones

Effect of acute arterial hypertension in stroke-prone and stroke-resistant SHR.

Acute transient hypertension by norepinephrine was loaded to stroke-resistant (SHRSR), stroke-prone (SHRSP), and normotensive Wistar Kyoto (WK) rats. (SHRSP were most sensitive to norepinephrine in young pre-hypertensive group.) Its effects on cerebral small vessels were studied using Evans Blue to detect the increase of vascular permeability. Severe macroscopic dye-leakages were observed in the areas of "recurrent branching" and "boundary zone", especially among young SHRSP, while SHRSR seemed to be least prone to dye-leakage both in young and adult groups. Among the adults, there was little difference between SHRSP and WK, probably because of the adaptive structural changes of arterial walls in SHRSP caused by long-standing hypertension.

Acute Disease

Cerebral stroke and myocardial lesions in stroke-prone SHR.

1) The histopathological abnormalities of the heart tended to be slightly severer in SHRSP with cerebrovascular lesions than those without cerebrovascular lesions. 2) However, SHRSP without cerebrovascular lesions also indicated abnormalities of VCG and histopathological findings. 3) Therefore, cerebral stroke may not directly affect or engender such myocardial lesions. 4) It is still remained to be solved whether the dysfunction of the heart with organic changes may partially contribute to the occurrence of cerebral stroke. 5) VCG appeared to correspond to the organic changes of the heart.

Animals

Incidence of stroke in an African City: results from the Stroke Registry at Ibadan, Nigeria, 1973-1975.

Studies based on hospital populations reported from negro communities in several countries in Africa suggest that cerebrovascular disease (CBVD) shows increasing mortality and morbidity in Africans although 2 decades ago CBVD was believed to be uncommon. We report the first study in the African to determine the incidence of stroke in an urban area, Ibadan, Nigeria.

Adolescent

Experimental studies on the pathogenesis and prophylaxis of stroke in stroke-prone spontaneously hypertensive rats (SHR).(1) Quantitative estimation of cerebrovascular permeability.

The cerebrovascular permeability quantitatively determined by the retention of 131I-human albumin in the perfused brains was increased in SHR, especially in stroke-prone SHR compared with normotensive Wistar-Kyoto, and confirmed the macroscopical or microscopical findings on the leakage into the brain or trypan blue or peroxidase injected intravenously 2 to 3 hours before sacrifice. The localization of increased vascular permeability in SHR corresponded to the predilection sites of cerebral hemorrhage or softening, which developed likely following the increased cerebrovascular permeability.

Animals