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

Nephroblastomas are induced in rats with N-Methyl-N-Nitroso-Urea, and selective renal artery occlusion is performed. This procedure has the same effect like occlusion by embolization. The effect of renal artery occlusion on the growth rate of nephroblastmas is controlled by angiography and gross and microscopic examinations up to 70 days following ischemia, the results are compared with a group of untreated nephroblastoma rats. There is a marked reduction of tumor size and a decrease in tumor proliferation. There is an immediate tumor cell death induced by acute and complete ischemia. Collateral blood vessels cause residual arterial blood supply of tumor parenchyma. There seems to be a correlation between collateral blood delivery and tumor size. Even 70 days after permanent ischemia there are areas of obviously absolute normal tumor cells. The conclusion of this experimental study demonstrated that growth rate of tumors can be reduced by ischemia although potentially malignancy still remains. Clinical embolization therapy is justified only in nonoperable patients with hypernephroma and with massive hematuria.
Radiologe 1977 Dec
PMID:[The influence of renal artery occlusion on tumor growth of experimental nephroblastomas (author's transl)]. 20 93

A direct, noninvasive method of assessing the oxidation-reduction potential of an intramyocardial respiratory chain component is described. The technique is based on the differences in spectral properties between the oxidized and reduced forms of nicotinamide adenine dinucleotide (NADH). The tissue surface fluorescence from intracellular NADH may be measured and documented photographically. Noose occlusion of a coronary artery produced detectable NADH fluorescence in 15 seconds in the subtended ischemic epicardium. This fluorescence of reduced pyridine nucleotide resolved following 60 seconds of reperfusion of the ischemic myocardium. The reduction of epicardial NADH with ischemia is a rapid and reversible process. A subsequent noose reocclusion resulted in a reproducible pattern of fluorescence. The technique of NADH fluorescence photography appears superior to current methods of assessing tissue oxygen supply:demand.
Ann Surg 1977 Dec
PMID:Evaluation of cardiac ischemia by NADH fluroescence photography. 20 34

The influence of hypercapnia, hypoxia and status epilepticus on cerebral cortex concentrations of adenosine, adenine nucleotides and cyclic AMP was studied on lightly anaesthetized (70% N2O) and artificially ventilated rats. Neither hypercapnia (arterial PCO2 about 80 and about 300 mmHg) nor hypoxia (minimal values of 19 mmHg) altered tissue concentrations of AMP, cyclic AMP or adenosine. Bicuculline-induced status epilepticus was accompanied by increased concentrations of cyclic AMP but adenosine concentration did not change. Experiments with ischemia, and those in which tissue hypoxia was exaggerated by unilateral carotid artery ligation, showed that tissue adenosine concentrations were elevated only when AMP concentration rose. It is concluded that the marked increase in cerebral blood flow which occurs in hypoxia and status epilepticus is unrelated to changes in tissue adenosine concentration and that the increase in cyclic AMP during neuronal hyperactivity is triggered by other mechanisms than adenosine accumulation.
Acta Physiol Scand 1978 Dec
PMID:Adenosine and cyclic AMP in cerebral cortex of rats in hypoxia, status epilepticus and hypercapnia. 21 98

Changes in cortical extracellular potassium activity ([K+]0), NADH fluorescence, and oxygen consumption were studied in anesthetized cats during pentylenetetrazol seizures. The effects of partial ischemia induced by either hypotension or intermittent carotid artery occlusion on these parameters were investigated. Nonischemic seizures were characterized by gradual generalized decreases in cortical NADH fluorescence and increases in O2 consumption, along with rapid increases in [K+]0, which then usually fell slightly as the ictal discharge continued. Ischemic seizures, on the other hand, were accompanied by complex changes in NADH fluorescence, by smaller delayed maximal increases in O2 consumption that lasted beyond the end of ictal activity, and by more sustained increases in [K+]0. The decay of [K+]0 after the termination of seizures in both nonischemic and moderately ischemic animals was not a monoexponential function: plots of ln delta [K+]0 versus time showed an initial linear decline (of slope M1) that rather abruptly slowed (to slope M2) after 2 to 5 sec and then often increased to the original rate. Both M1 and M2 were proportionately decreased by ischemia. In addition, the rate of [K+]0 removal could be slowed by acute ischemia induced either during or after the end of ictal activity. The initial rate of postictal [K+]0 removal (M1) was found to be linearly and inversely related to the level of cortical NADH fluorescence at the time of seizure termination. The results of this study suggest that an O2-dependent transport mechanism plays a major role in the removal of [K+]0 during and following the termination of generalized pentylenetetrazol seizures in the cat.
Epilepsia 1979 Dec
PMID:Effects of ischemia on the removal of extracellular potassium in cat cortex during pentylenetetrazol seizures. 22 67

Capillary blood circulation following experimental wounding was observed by fluorescein angiography. Contralateral punch wounds 1.5 mm in diameter were made in healthy mandibular labial attached gingiva of 31 volunteers. Areas of ischemia were clearly visible angiographically 6 hours after wounding and were significantly greater in area (P less than 0.05) and wider (P less than 0.01) for wounds in the long axis of mandibular incisors (N = 14) than those on the vertical midline of the gingival papillae (N = 17). The ischemic changes occurred exclusively cranial to the experimental wounds. By the third day the epithelium adjacent to the wound margin in the central part of the ischemic area had necrotized, thus extending the wound coronally. By the seventh day the axial wounds were significantly (P less than 0.001) larger than the papillary wounds. The data strongly suggest that the blood supply of mandibular labial attached gingiva is preferentially oriented in an apico-coronal direction and that the capacity for collateral circulation is dependent upon local differences in vascular structure. The findings are applicable to flap design in periodontal surgery.
J Clin Periodontol 1979 Dec
PMID:Gingival blood circulation after experimental wounds in man. 29 89

Rabbits were subjected to vascular injuries in an attempt to cause ocular ischemia and rubeosis. Occlusion of the ipsilateral common carotid artery showed fluorescein angiographic evidence of iris ischemia, but no rubeosis. Occlusion of two or more vortex veins caused iris ischemia, vasodilation, and angiographically visible neovascular capillaries on the iris. Histology confirmed the presence of thin-walled, superficial neovascular channels. The stimultaneous occlusion of the carotid artery and of two or more ipsilateral vortex veins also produced angiographic and histologic evidence of iris ischemia and neovascularization. These results confirm that venous flow impairment is a more efficient stimulus to neovascularization than ischemia due to arterial insufficiency. Nevertheless, in none of the animals could a neovascular response comparable to human rubeosis be elicited, and it is concluded that vascular lesions to the anterior segment are not an adequate model to study rubeosis.
Albrecht Von Graefes Arch Klin Exp Ophthalmol 1978 Dec 08
PMID:Experimental rubeosis of the iris in rabbits. 31 Nov 62

The effect of experimentally induced uniocular trauma was investigated in the adult albino rabbit by means of iris fluorescein angiography. Paracentesis, blunt trauma, occlusion of all four vortex veins or of the two long posterior ciliary arteries, or local instillation of nitrogen mustard, were performed in a number of animals, some of which received systemic aspirin preoperatively. Iris angiograms of the injured and the contralateral eye were performed immediately after the traumatic insult. The injured eye always showed an increased permeability to fluorescein. Except for paracentesis, the ipsilateral response often included ischemia of the iris. The contralateral eye always showed an increase in fluorescein permeability into the aqueous. In some cases, sector ischemia of the contralateral iris was seen. Aspirin inhibited some ipsilateral responses but had no effect on the consensual reactions. It is concluded that ipsilateral trauma almost invariably causes a contralateral reaction in the rabbit eye, which is more severe if the injury creates ischemia of the iris. Since these reactions are inefficiently blocked by aspirin, they are not prostaglandin-mediated. The interocular pathway involved may be neural or vascular in nature.
Albrecht Von Graefes Arch Klin Exp Ophthalmol 1978 Dec 15
PMID:Anterior segment reactions after experimental trauma to rabbit eyes. 31 Nov 67

To determine the importance of different methods of myocardial protection for combined aortic valve replacement and coronary revascularization, we analyzed the records of 82 consecutive patients who underwent the combined procedure between 1973 and 1978. Sixty-three (77%) had angina and 63 (77%) were in New York Heart Association Functional Class III or IV. Moderate to severe left ventricular impairment was present in 59%, and the mean number of diseased vessels was 1.9 per patient. Group I consisted of 18 patients with intermittent ischemia, almost all of whom had operation between 1973 and 1976. Group IIa consisted of 24 patients operated on between 1973 and December, 1976, with coronary perfusion, and Group IIb had 18 patients in whom a similar technique was used in 1977 and 1978. Group III consisted of 22 patients operated on in 1977 and 1978 in whom cold chemical cardioplegia was used. The early mortality (less than 30 days) for Group I was 50% and for Group IIa 29%. There were no deaths in Group IIb and Group III. The incidence of perioperative myocardial infarction was 21% in Group I, 6% in Group IIa, 11% in Group IIb, and zero in Group III. The incidence of cardiogenic shock requiring prolonged inotropic support and intraaortic balloon counterpulsation was significantly less in Group III (9%) than in Group IIb (50%) (p less than 0.05). If other manifestations of myocardial injury, such as perioperative infarction and cardiogenic shock requiring intraaortic balloon counterpulsation or inotropic support, are taken into consideration, cold chemical cardioplegia appears to provide better myocardial protection than coronary perfusion of the fibrillating heart.
Ann Thorac Surg 1979 Dec
PMID:The importance of myocardial protection in combined aortic valve replacement and myocardial revascularization. 31 12

We measured indices of the renin-aldosterone system and body-fluid spaces in 11 adolescents who had received a renal transplant after removal of their own diseased kidneys. None had hypervolemia but 6 had hypertension. Renal angiography revealed greater than 50% luminal occlusion by allograft renal-artery stenosis (RAS) in only the 3 patients who had severe hypertension refractory to conventional medical therapy. Excessive peripheral plasma renin activity (PRA) distinguished these patients from those who had less severe stenosis or normal angiogram, and diuretic stimulation heightened the PRA differences. We conclude that significant allograft RAS does not necessarily act like a typical single-kidney Goldblatt model until after volume depletion. Our findings indicate that peripheral PRA values can be used to assess the degree of graft ischemia clinically. This permits early identification of patients who have severe RAS that probably will be difficult to control medically, and, therefore, should be followed closely with a view of reconstructive vascular surgery before further deterioration of renal function.
Clin Nephrol 1978 Dec
PMID:Allograft renal-artery stenosis: increased peripheral plasma renin activity as an early indicator of uncontrollable hypertension. 36 8

Morphometrical relations of human placental villi from 14 normal placentas of the 38th to 42nd week of pregnancy terminated by Cesarean section were examined in relation to the method of fixation. Villous tissue was obtained from central areas of the in situ placenta with intact maternal circulation by means of puncture aspiration and punch biopsy. Further punch biopsies were performed 2, 5, 10 and 20 min after manual removal of the placenta. Semithin sections of these villi were photographed and examined morphometrically. The findings demonstrate clear effects on quantitative data as a result of the period of ischemia between manual removal and fixation of tissue. Significant changes of several parameters (mean trophoblastic volume, size of epithelial plates, volume of connective tissue, volume of fetal vessel lumina, etc.) occur as early as 2 min after separation of the placenta from the maternal circulation. They are mostly related to a collapse of intravillous vessels. The villous branches may be classified according to structure and morphometry, if they have been obtained under optimal conditions of fixation and prior to any vascular collapse.
Arch Gynecol 1978 Dec 29
PMID:[Problems of distinction of normal, artificial, and pathological structures in mature human placental villi. II. Morphometrical studies on the influence of the mode of fixation (author's transl)]. 36 90


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