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

Histopathologic examination of six, adult human eyes revealed "rosette-like" structures in the retina which appear to have developed after maturation of the retina. These structures resemble dysplastic rosettes which are generally interpreted as a sign of maldevelopment of the retina (retinal dysplasia). The underlying lesions in the eyes of these patients were ocular ischemia, sickle-cell retinopathy, diabetic retinopathy, central retinal vein occlusion, and trauma. It is suggested that a distinction should be made between these degenerative-regressive changes and dysplastic rosettes which represent an abortive attempt of regeneration by germinal cells.
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PMID:Light and electron microscopic study of dysplastic rosette-like structures occurring in the disorganized mature retina. 16

Laser photocoagulation has changed the visual prognosis of diabetic patients affected by retinopathy. It aims to lower the risk of blindness of diabetic patients. The goal of photocoagulation is to reduce the tissue damage of microangiopathic origin expressed by nonperfusion areas and permeability abnormalities that are responsible for retinal ischemia and oedema respectively. Loss of visual acuity in the diabetic is due mainly to two causes : first, vitreous hemorrhage with its dramatic loss of vision; secondly, macular cystoid oedema, occuring more commonly and with progressive loss of central vision. The efficiency of pan-retinal photocoagulation in reducing the risk of vitreous hemorrhage and consequent blindness in patients with disc or preretinal newly formed vessels, has been ascertained by American and British randomised studies. The indications, technics and results of photocoagulation in non-proliferative diabetic retinopathy are the subject of many studies. Only photocoagulation for macular oedema due to intra-retinal microvascular abnormality has shown to be of benefit.
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PMID:[Treatment of diabetic retinopathy with laser photocoagulation (author's transl)]. 38 89

In 45 eyes of rhesus monkeys, five types of central retinal vascular occlusion were produced by lateral orbitotomy: group 1, central retinal vein occlusion (CRVO) alone; group 2, CRVO with simultaneous central retinal artery (CRA) occlusion; group 3, CRVO with transient clamping of the CRA for either 2 to 2 1/2 hours (group 3A) or 6 to 7 1/2 hours (group 3B); and group 4, CRVO with segmental retinal ischemia. The eyes were examined by fundus photography and fluorescein angiography for up to nine months. Group 1 developed venous stasis retinopathy (VSR) and group 3B hemorrhagic retinopathy (HR). In group 4 the ischemic and nonischemic segments of the retina developed segmental HR and VSR, respectively. Groups 2 and 3A developed neither VSR nor HR. Retinal capillary obliteration occurred in groups 2 and 3B and in the ischemic part of group 4, starting one to three weeks after the occlusion and progressing thereafter. These studies indicate that clinically co-called CRVO consists of two distinct entities: VSR and HR, with retinal ischemia playing an important role in the production of HR. On the basis of the present and other available information, the pathogenesis of CRVO was concluded to be multifactorial.
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PMID:Experimental retinal vascular occlusion. I. Pathogenesis of central retinal vein occlusion. 41 9

In a study of 130 cases of unilateral retinal vein occlusion uncomplicated by rubeosis, we found that more than 80% of the patients had a lower intraocular pressure (IOP) in the eye with the occlusion than in the fellow normal eye. The reduction of IOP was greater with central than with branch vein occlusion, greater with hemorrhagic than with venous stasis retinopathy, and greater in patients who had high pressures in their fellow eyes. The pressure reductions persisted during follow-up periods of up to two years. How retinal vein occlusion lowers IOP is obscure and may involve more than one mechanism. Outflow facility was increased (compared to the fellow eye) in hemorrhagic retinopathy and in branch vein occlusion, both of which are association with retinal ischemia, but not in venous stasis retinopathy. Calculated rates of aqueous formation were low in central vein occlusion but not in branch vein occlusion.
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PMID:Ocular hypotony following retinal vein occlusion. 65 20

A procedure was developed in the laboratory for pancreatic allotransplantation in pancreatectomized dogs. Dogs with such grafts have survived for many months when treated with azathioprene and prednisone to prevent rejection. Contrary to usual beliefs, the pancreas is not unduly sensitive to total ischemia since it has been possible to successfully preserve a canine pancreas in vitro with hypothermia for periods up to 24 hours. Such preserved pancreas' have then been allotransplanted into pancreatectomized dogs with survival of the dogs for long periods. We have now done pancreaticoduodenal allotransplantation in 13 patients with juvenile onset diabetes mellitus. Nine of these patients also had renal failure and received simultaneously a renal allograft taken from the same cadaver. In all but one of these patients the pancreas functioned immediately. Two patients with juvenile onset diabetes mellitus and severe retinopathy but without terminal renal failure have received pancreaticoduodenal allografts alone. In both of these patients the pancreas functioned immediately but problems with the duodenum necessitated the removal of the pancreaticoduodenal allograft which did not show signs of rejection. As a result of the findings of increased sensitivity of the kidney and duodenum to rejection we have now modified our technique to transplant the pancreas alone. This technique was used in one patient with juvenile onset diabetes mellitus and severe retinopathy. Her renal function was only moderately reduced. The pancreatic allograft initially functioned normally but then was removed at 28 days because of clinical signs of rejection of the pancreas which were confirmed by the microscopic findings. Despite the promise of islet-cell transplantation, no long term functioning allografts have resulted in animals or man. Thus we need to continue with whole organ pancreatic allografts by various techniques if diabetes mellitus is to be controlled.
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PMID:Transplantation of the pancreas. 82 66

In a population of 744 diabetics composed mainly of elderly female patients, 172 developed hypertension after the onset of diabetes. Compared to normotensive diabetics, they had an increased prevalence of diabetic retinopathy (p less than 0.001), cerebral accidents, ischemic disorders of the lower limbs and a decreased glomerular filtration rate (p less than 0.05); they are frequently insulin-dependent and difficult to manage. In 173 other indivuals the diabetes emerged several years after the hypertension. This group was characterized by relatively easily controlled blood sugar and increased prevalence of angina and myocardial infarction (p less than 0.001). The association of hypercholesteremia with hypertension increases the risk of coronary disease (p less than 0.02) and, to a lesser degree, of glomerular insufficiency. The prevalence of coronary symptoms increases with obesity (p less than 0.05) while retinopathy increases with insulin dependence (p less than 0.001). From this information it may be concluded that the importance of various risk factors in the diabetic chiefly varies according to the vascular territory involved: cerebral vascular accidents occur mainly in hypertensives, while the presence of retinopathies, proteinuria and peripheral ischemia is directly related to the diabetes and particularly to insulin dependence. The risk of coronary lesions increases considerably when hypertension is added to the diabetes, with an even greater risk in the case of a diabetic, hypertensive, hypercholesterolemic nexus.
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PMID:[Factors of arterial and renal complications in diabetes]. 112 60

Spontaneously occurring surface wrinkling retinopathy occurreed in 17 eyes of 16 patients and was not related to pervious surgery, retinal vascular disease, or obvious ocular inflammation. Visual symptoms were not severe and follow-up suggests that the usual course of surface wrinkling is usually benign. However, 2 eyes progressed to 20/300, so that there is a chance of considerable visual deterioration in some cases. The vitreous may or may not be detached. The ophthalmoscopic features of a wrinkled shagreen, tortuous vessels pulled toward a nidus, and intraretinal hemorrhages were seen. The leakage of fluorescein into the retina is emphasized in this series and may be fairly marked. The possible causes and mechanism of wrinkling are discussed with emphasis on mild chronic ischemia and posterior vitreous collapse.
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PMID:Spontaneous surface wrinkling retinopathy. 113 79

Pathogenesis of occlusion of the central retinal vessels, based on experimental and clinical findings, is discussed. It suggests that the so-called "central retinal vein occlusion" represents not only occlusion of the central retinal vein but also retinal arterial ischemia. Based on this pathogenesis the following terminology is recommended for central retinal vascular occlusion: (a) Ischemic retinopathy is due to occlusion of the central retinal artery. (b) Venous stasis retinopathy is due to occlusion of the central retinal vein alone. (c) Hemorrhagic retinopathy is due to occlusion of the central retinal vein associated with retinal ischemia. Clinical findings of (b) and (c) are compared which indicate that the two conditions are distinct entities and unfortunately so far have been dumped under a common heading of so-called "central retinal vein occlusions". Such a distinction is extremely important before any attempts are made to evaluate their natural history or effects of any therapy on them.
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PMID:So-called "central retinal vein occlusion". I. Pathogenesis, terminology, clinical features. 125 May 71

Diabetes mellitus (DM)-linked metabolic alterations and hypertension concomitantly accelerate or precipitate cerebrovascular and coronary heart disease, nephropathy, retinopathy and widespread macroangiopathy, thereby conferring to diabetic patients a very high risk of morbidity, disability and early death. Therefore, the long-term care for diabetic patients should be aimed at concomitant metabolic and blood pressure (BP) control. Dietary measures are indispensable; a high fibre, low fat, low salt diet is recommended, complemented with caloric restriction and physical exercise when body weight is above the ideal. Antidiabetic pharmacotherapy involves an unresolved dilemma. The desired achievement of euglycemia necessitates effective levels of insulin, but hyperinsulinemia (due to parenteral [over]treatment in insulin-dependent DM) is suspected to promote atherogenesis and represents a coronary risk factor and perhaps even facilitates hypertension. Considering antihypertensive pharmacotherapy, thiazide-type or loop diuretics are problematic drugs in DM because they can aggravate metabolic alterations. These agents also seem to exert only a limited preventive or regressive effect on left ventricular hypertrophy (LVH); beta-blockers are also not considered ideal, since they decrease the awareness of hypoglycemia and tend to promote glucose intolerance. Unselective beta-blockers in particular promote peripheral ischemia and insulin-induced hypoglycemia, while beta-blockers without intrinsic sympathomimetic activity lower serum HDL-cholesterol. Calcium antagonists and ACE inhibitors have equivalent antihypertensive efficacy, do not impair carbohydrate and lipid homeostasis or peripheral perfusion and can effectively improve LVH. Certain ACE inhibitors may even slightly ameliorate abnormal insulin sensitivity and plasma glucose levels. While alpha-blockers share most of these desirable properties, these agents are more prone to precipitate orthostatic hypotension in the diabetic patient. The non-thiazide diuretic indapamide and the serotonin2-antagonist ketanserin also combine antihypertensive efficacy with metabolic neutrality. The ultimate goal of therapy is to improve life prognosis. In essential hypertension, conventional drug treatment based on diuretics in high dosage satisfactorily reduced cerebrovascular but not coronary complications or sudden death. In diabetic patients, the influence of antihypertensive therapy on prognosis has not been assessed prospectively. Based on retrospective analyses, Warram et al reported a 3.8 times higher mortality in diabetics treated with diuretics alone, than in diabetics with untreated hypertension (Arch Intern Med. 1991;151:1350). H. H. Parving calculated that effective BP control in patients with diabetic nephropathy might reduce 10 year-mortality from about 65 to 20 percent (J Hypertension. 1990; 8[Suppl 7]:187).(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Antihypertensive therapy in diabetic patients. 128 10

Retinal vascular manifestation is the most common form of ophthalmic involvement in patients with systemic lupus erythematosus (SLE). Most frequently these consist of cotton-wool spots with or without intraretinal hemorrhages. Although rare, a more severe retinal vaso-occlusive disease, termed retinal vasculitis, has been described. We report on a 37-year-old white female with a 13-year follow-up of chronic discoid lupus erythematosus, which suffered massive bilateral visual loss coincident with the systemic exacerbation of her disease (proteinuria, pneumonia, serositis, leucopenia). The diagnosis of SLE was established with reference to the revised ARA-criteria (American Rheumatism Association). Ophthalmoscopy and fluorescein angiography revealed the typical aspect of a SLE-associated vaso-occlusive retinopathy on both eyes with marked ischemia of the macula. Immediate maximal immuno-suppressive therapy, early performed panretinal photocoagulation and subsequent cryoretinopexy did not stop the progression of the disease. Six months after the initial event vascularisations of the disc and rubeosis iridis occurred, but no secondary glaucoma up to date. In this patient, the almost complete absence of characteristic autoantibodies and immunological markers was striking. The correlation with other lupus manifestations, different therapeutic concepts and prognostic factors in SLE-associated retinal vasculitis are discussed.
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PMID:[Severe occlusive bilateral retinal vasculitis within the scope of seronegative systemic lupus erythematosus]. 147 91


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