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Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The pattern and pathogenesis of nonlocalizing visual disturbances, associated with optic disc edema (ODE). raised cerebrospinal fluid pressure, and intracranial space-taking lesions were investigated experimentally in rhesus monkeys with simulated progressive brain tumor and clinically in patients with benign intracranial hypertension. The visual disturbances occurring in one of both eyes were of three types: recurrent attacks of transient obscuration, permanent blindness, and various types of visual field defects. The studies indicate that the visual disturbances are usually due to two mechanisms. The most common is ischemia of the optic disc secondary to ODE. The other, rarer mechanism probably consists of the space-taking lesion causing downward herniation of the parahippocampal gyrus into the tentorial notch, producing compression of the lateral geniculate body and optic tract.
Arch Ophthalmol 1977 Sep
PMID:Optic disc edema in raised intracranial pressure. VI. Associated visual disturbances and their pathogenesis. 40 82

We have investigated the rate of rise of myocardial PCO2 (PmCO2) after coronary artery occlusion using a new method for this measurement. Previous studies of PmCO2 have been limited by the slow response of the only available method, and no increase in MmCO2 prior to 3 minutes after occlusion has been found. We have implanted a miniature PCO2 electrode, with a 63% response time of 14 seconds, into the left ventricle of 14 open-chest dogs. After abrupt coronary occlusion, PmCO2 began to rise in 13.6 +/- 1.1 seconds in heparinized dogs and in 7.5 +/- 0.7 seconds in unheparinized dogs. The subsequent magnitude of the increase in PmCO2 was 24, 88, 171, and 222 mm Hg at 2, 5, 10, and 15 minutes after occlusion. The rate of rise of PmCO2 was essentially linear from 1 minute to 10 minutes at a rate of 18.3 mm Hg/min. The rate of rise was slower during the first 30 seconds after occlusion (6.1 mm Hg/min) and also from 30 seconds to 1 minute (9.7 mm Hg/min). This rate of rise is much greater than that previously observed and reflects the severe myocardial acidosis developing during ischemia. A rise in PmCO2 is one of the earliest metabolic changes that has been observed during myocardial ischemia.
Circ Res 1979 Sep
PMID:Rate of rise of myocardial PCO2 during early myocardial ischemia in the dog. 45 97

Brief periods of ischemia have been shown to produce marked reactive hyperemia in both red (slow) and white (fast) skeletal muscle. However, evidence is lacking for specific vasodilator metabolites which are rapidly produced in ischemic skeletal muscle. The present study examined the effects of 1 and 3 minutes of ischemia on creatine phosphate (CrP), adenine nucleotide metabolism, and anaerobic glycolysis in red anterior (ALD) and white posterior latissimus dorsi (PLD) muscles of the chicken. Tissue metabolite concentrations were determined from perchloric acid or trichloroacetic acid extracts using enzymatic assay or high pressure liquid chromatography. CrP or adenine nucleotides were not significantly altered in either muscle following 1 or 3 minutes of ischemia. However, adenosine increased by 611% in the ALD at 1 minute. Following 3 minutes of ischemia, adenosine concentrations were elevated by 439% and 201% in the ALD and PLD, respectively. The PLD showed the greatest increases in inosine and IMP. Inorganic phosphate increased by 67% and lactate increased by 142% in the ALD at 3 minutes. The PLD, which is reported to have a high anaerobic glycolytic capacity, showed no increase in lactate. These results support the hypothesis that adenosine may be a mediator of akeletal muscle reactive hyperemia following short periods of ischemia.
Circ Res 1979 Sep
PMID:Effects of ischemia on tissue metabolites in red (slow) and white (fast) skeletal muscle of the chicken. 45 3

The present study reports on the epicardial spread of excitation during premature beats and during the initial stages of ventricular fibrillation, both of which were induced by single-test stimuli during regional ischemia or local hypothermia. Simultaneous recording of the activity at 48 epicardial sites on the right ventricle of dog hearts enabled us in some instances to demonstrate a circus movement.
Circ Res 1979 Sep
PMID:Circus movement in canine right ventricle. 45 4

Reentrant ventricular arrhythmias (RVA) were analyzed in dogs 3--7 days after ligation of the anterior descending coronary artery using averaged "composite" recordings of electrical activity of reentrant pathways (RP) from the epicardial surface of the infarction zone (IZ). Verapamil (V) and D-600 (D) (0.2--0.5 mg/kg i.v.) resulted in slight-to-moderate improvement of conduction in RP with abolition of spontaneous RVA and RVA initiated by premature depolarizations. The effect of V was not blocked by pretreatment with propranolol (0.5 mg/kg i.v.). Using a standard microelectrode technique and strips of epicardial muscle from the IZ, D (0.5--1 X 10(-6) g/ml) slightly improved the upstroke velocity and membrane responses of depressed ischemic cells. In contrast, tetrodotoxin (5 X 10(-7) g/ml) further depressed or abolished action potentials of ischemic cells. We conclude: 1) the moderate antiarrhythmic effect of V and D on RVA is the result of improved conduction in RP; 2) this action is partly explained by improvement of a depressed sodium channel and is not related to catecholamine release; 3) slow-response action potentials play no significant role in the genesis of ischemia-related RVA, which probably results from depression of the fast response.
Circulation 1979 Sep
PMID:Reentrant ventricular arrhythmias in the late myocardial infarction period. 7. Effect of verapamil and D-600 and the role of the "slow channel". 45 24

Currently, the most favored surgical procedure used to restore normal peristalsis to massively dilated adynamic ureters is ureteral tailoring. This procedure, however, seriously jeopardizes the ureter's blood supply and frequently results in ischemia with ureteral stenosis and further renal deterioration. To preserve the distal ureter's vasculature a new technique of reducing ureteral caliber and restoring normal peristalsis with minimal disruption of the blood supply was developed and performed in 14 dogs with excellent results.
Invest Urol 1979 Sep
PMID:Ureteral plication. A new concept in ureteral tailoring for megaureter. 46 16

The efficacy of surface cooling and intraluminal antiseptic solutions for short term preservation of intestinal segments in preparation for free tissue transfer were investigated. Five segments of the small intestine and five segments of the colon were allocated to each group as follows: group 1, ischemia at 37 degrees C.; group 2, ischemia at 6 to 12 degrees C., and group 3, ischemia at 6 to 12 degrees C. plus povidone-iodine intraluminally. Histologic grading of segments allowed assessment of the efficacy of short term protection against ischemic changes. Surface cooling effectively prevented histologic evidence of ischemia. No additional benefit was observed using povidone-iodine intraluminally. Significant changes in tissue water content and evidence of bacterial invasion were not observed.
Surg Gynecol Obstet 1979 Sep
PMID:Effects of cooling and intraluminally administered antiseptics on surgically induced ischemia of the intestine in dogs. 47 99

To avoid the compensatory hemodynamic responses, which have limited interpretation of hemoglobin-oxygen affinity modifications in animal experimentation, an isolated blood-perfused rabbit heart model providing metabolic, functional, and vectorcardiographic measurements has been developed. Fixed-flow perfusions of unchanged or affinity-modified red blood cell suspensions were carried out to assess the benefits of high affinity during hypoxic hypoxia and of low affinity during posthypoxic recovery. Using fully saturated suspensions, the influence of affinity level during restricted flow and reperfusion was also studied. Higher myocardial oxygen consumption (MVO2) was associated with high-affinity blood during mild hypoxia and low-affinity blood during posthypoxic recovery. At low flows, heart rate and MVO2 tended to be lower in high-affinity perfusions, and to recover more completely during low-affinity reperfusions. Ventricular function, vectorcardiographic patterns, and lactate levels were affected by hypoxia and ischemia, but not by level of affinity. The relevance of these observations to the therapeutic potential of hemoglobin-oxygen affinity modification is discussed.
Am J Physiol 1979 Sep
PMID:Application of an isolated heart model to investigate blood-oxygen delivery. 47 72

Use of a motion-compensated micropipette holder, which senses cardiac motion and lifts and lowers the micropipette and supporting apparatus in synchrony with the heart beat, allows for stable recording of transmembrane action potentials from subepicardial cells of an in vivo beating heart in an open-chest dog without significantly impairing cardiac hemodynamics. This technique may be used to study the effects of ischemia, hypertrophy, or pharmacologic agents on the cellular electrophysiological parameters of subepicardial ventricular cells of an in vivo beating heart.
Am J Physiol 1979 Sep
PMID:Intracellular recording from beating heart in situ using a special micropipette holder. 47 77

To evaluate the effect of prostaglandin inhibition on the renal blood flow of the ischemic kidney, we administered indomethacin to 10 anesthetized dogs with renal artery stenosis and contralateral nephrectomy. Following the operation to produce renal ischemia, there was an increase of blood pressure associated with an increase of renin and the prostaglandins F1 (PGF1), and E (PGE). The administration of indomethacin to the intact, normotensive animals caused the anticipated decrease of prostaglandin E, renin, and renal blood flow. However, in the hypertensive dogs, indomethacin caused a paradoxical 45 per cent increase in the renal blood flow, despite a 44 per cent decrease of prostaglandin E. PGF1, PGE, renin, and erythropoietin exhibited the anticipated decreased levels. The study suggests that prostaglandins may not be the sole important factor in the regulation of renal blood flow in the presence of ischemia. Other important factors likely include the renin-sensitive angiotensin, the adrenergic, and the kallikrein-kinin systems.
Urology 1979 Sep
PMID:Paradoxical increase of renal blood flow in anesthetized hypertensive dog treated with indomethacin. 48


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