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Query: UMLS:C0011849 (diabetes)
 277,896 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The development of insulitis in animal models of immune-mediated diabetes mellitus is preceded by an influx of macrophages into the islets. In this study, ICR mice were given four 30-mg/kg doses of streptozocin over 36 h to induce insulitis. The islets were subsequently isolated and cultured in suspension. A macrophage-specific islet infiltration was observed within 48 h of the first drug injection. Concurrent with this leukocyte influx, enhanced in vitro release of a macrophage-specific chemotactic lipid by islets from streptozotocin-administered animals was observed. By chromatographic analysis, the islet-derived chemotactic factor appears to resemble a moderately polar complex lipid that is distinct from previously characterized lipid chemoattractants. Secretion of the factor is not dependent on cyclooxygenase activity. Identification of this lipid may provide important insights into the etiology of insulin-dependent diabetes mellitus and other autoimmune diseases.
Diabetes 1991 Nov
PMID:Macrophage-specific chemotactic lipid release by in vivo streptozocin-administered mouse islets. 183 1

During the last fifteen years it has become evident that in diabetes there is an increased vasoconstrictor tendency in the arterial bed of different organs. This vasoconstrictor tendency is most expressed in the coronary arteries where sympathetic stimulation exerts vasodilation in the healthy and vasoconstriction in the diabetic arterial bed. Accordingly, myocardial tissue blood flow decreases during hypoxia in the diabetic, whereas it increases in nondiabetic states. Furthermore, 48 hours after ligation of the anterior left descending coronary artery the infarcted myocardial zone was extended below its first major oblique branch in diabetic dogs compared to nondiabetic ones. Since pretreatment with adrenergic antagonists or with cyclooxygenase inhibitors diminished considerably the increased vasoconstrictor tendency in the diabetic state alterations in the endothelium as well as in adrenergic vascular and prostaglandin mechanisms are involved in the pathomechanisms of this phenomenon. Moreover, after mechanical removal of the endothelial layer in coronary arterial strips the maximum force generated by diabetic vessels exceeded the maximum contraction produced by nondiabetic arteries, and the dose-response curve of diabetic arteries to phenylephrine was steeper than in nondiabetic strips. All these phenomena appeared at an early stage when macro- and microscopic alterations could not yet be observed in the vessels. Sodium nitrite or papaverine evoked similar vasodilation in the diabetic and nondiabetic coronary arterial bed.
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PMID:The role of diabetic vascular alterations in the development of myocardial ischemia. 190 90

The role of arachidonic acid metabolites in renal autoregulatory responses to changes in pressure was examined in rat isolated perfused kidneys. We also studied the influence of diabetes, a condition associated with hyperfiltration and altered renal eicosanoid production, on autoregulatory responses. The perfused rat kidney demonstrated autoregulation of flow within a pressure range of 100-150 mm Hg, with no differences between diabetic and control rat kidneys. Nifedipine resulted in vasodilatation and loss of autoregulation. Inhibition of the cyclooxygenase pathway of arachidonic acid metabolism with indomethacin failed to alter autoregulatory capacity. Similarly, inhibition of lipoxygenase with BW755C or NDGA, or inhibition of cytochrome P450-dependent enzymes with NDGA, clotrimazole or 7-ethoxyresorufin were without effect on autoregulatory responses. In vivo treatment with stannous chloride to deplete renal cytochrome P450-dependent enzymes also failed to modify autoregulatory responses. These results argue against a role of arachidonic acid metabolites in autoregulation of perfusate flow in the isolated kidney.
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PMID:Evidence against a role of arachidonic acid metabolites in autoregulatory responses of the isolated perfused kidney of the rat. 190 58

In 33 insulin-dependent, I and II type diabetic patients the authors evaluated the intraplatelet concentration of 12-hydroperoxyeicozatetraenoic acid (12-HPETE) and malonylodialdehyde (MDA) which are the products of lipoxygenase (LO) and cyclooxygenase (CO) metabolism of arachidonic acid (AA) in blood platelets. Moreover, in all patients, determinations of cholesterol total lipids, phospholipids, triacylglycerols were performed as well as serum lipoproteinogram. The studies were done in diabetic ketoacidosis and 2 weeks after compensation of diabetes was attained. Sixty healthy persons, with no changes in the coagulation system, constituted the control group. In patients with diabetic ketoacidosis a higher intraplatelet concentration of 12-HPETE (7.2 +/- 4.0 nmol/10(9) platelets) was found as compared with the values observed in the control group (4.7 +/- 2.1 nmol MDA/10(9) platelets); p less than 0.01. Intraplatelet MDA concentration did not, however, show a statistically significant difference. When compensation of diabetes was obtained the mean intraplatelet 12-HPETE concentration fell to values close the normal ones (5.5 +/- 3.4 nmol MDA/10(9) platelets). Nevertheless, the results of comparative determinations of mean values of both 12-HPETE and MDA concentrations in ketoacidosis as well as in compensated diabetes did not show statistically significant difference. High intraplatelet 12-HPETE concentration in diabetic ketoacidosis may be a cause of the formation or intensification of atherosclerotic changes, typical of this group of patients. The studies did not prove any correlation between the intraplatelet concentration of AA metabolism products and blood glucose concentration and lipid metabolism products. Neither was there any correlation between 12-HPETE and MDA concentration and the duration of clinically symptomatic diabetes.
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PMID:[Evaluation of platelet malondialdehyde and 12-hydroperoxyeicosatetraenoic acid in type I and II diabetic patients with ketoacidosis and after clinical complications]. 191 Jan 67

The majority of cases of impotence are associated with vascular risk factors such as diabetes, hypercholesterolemia, hypertension and smoking. These factors induce impairment of endothelium-dependent relaxation of blood vessels in man and in experimental animals. In this study the effects of hypercholesterolemia on the reactivity of rabbit corpus cavernosum smooth muscle strips to endothelium-dependent and endothelium-independent agents were investigated. New Zealand White rabbits (n = 14) were randomly divided into control and treatment groups. The control group (n = 7) received a regular diet while the treatment group (n = 7) was fed a diet of 0.5% cholesterol and 4% peanut oil for 10 weeks. Animals were then sacrificed and the corporal tissue studied in organ chambers for isometric tension measurement. Tissue was contracted with phenylephrine and concentration-dependent relaxation to acetylcholine, in the presence and absence of indomethacin, and to nitroprusside were examined. Blood level of cholesterol in the cholesterol-fed group was significantly higher compared to the control group. Contractions to phenylephrine were similar in both groups. Hypercholesterolemia, however, inhibited relaxation to acetylcholine but did not alter relaxation to nitroprusside, a cyclic guanosine monophosphate (cGMP)-dependent, direct smooth muscle dilator. Indomethacin enhanced the relaxations to acetylcholine in both control and cholesterol-fed groups but did not correct the difference in the relaxation to acetylcholine between both groups. It is concluded that hypercholesterolemia impairs endothelium-mediated relaxation of rabbit corpus cavernosum smooth muscle. The mechanism for the endothelial dysfunction does not appear to involve alteration in cyclooxygenase products of arachidonate or the cGMP-dependent relaxation of corporal smooth muscle. Impairment of endothelium-dependent relaxation of corporal smooth muscle may contribute to the pathophysiology of impotence associated with hypercholesterolemia in man.
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PMID:Hypercholesterolemia impairs endothelium-dependent relaxation of rabbit corpus cavernosum smooth muscle. 205 97

The great discovery by Furchgott of the relaxing factor released from the endothelium (EDRF) awakened us to the necessity to reevaluate the functional importance of endothelial cells that have been chemically or physically stimulated. EDRF was first demonstrated to be released by acetylcholine, substance P, bradykinin and calcium ionophore A23187; thereafter, many substances have been found to release EDRF. This factor is quite unstable, is not produced by cyclooxygenase, and is an activator of soluble guanylate cyclase that synthesizes cyclic GMP; its action is suppressed by antioxidants via the superoxide anions produced, potentiated by superoxide dismutase and abolished by methylene blue and oxyhemoglobin. Recently, the role of lipoxygenase products in the production of EDRF was evaluated with new 5-lipoxygenase inhibitors without antioxidant activity. During the last couple of years, the actions and chemical properties of EDRF were verified to be quite similar to those of nitric oxide (NO); therefore, the hypothesis of "EDRF = NO" is widely being accepted. NO is produced from L-arginine via catalysis by an enzyme that is activated by Ca2+. The enzyme activity is inhibited by L-monomethyl arginine and other L-arginine analogs. Chemical and physical stimulations increase intracellular Ca2+ in endothelial cells that seems to be associated with K(+)-channel opening and hyperpolarization. Current interests are directed to the possible roles of NO in the regulation of nerve function. There are evidences suggesting that NO modulates adrenergic nerve function in blood vessels and some brain cell functions regulated by cellular cyclic GMP. Particularly, NO may be a transmitter substance in non-adrenergic, non-cholinergic vasodilator nerves innervating the cerebral arteries. Future investigations will determine the physiological roles of EDRF or NO and its relationships to pathophysiology of vascular dysfunctions, such as vasospasm and those related to hypertension, diabetes, aging, etc., and the extended roles of NO in nerve function, inflammation, immune reactions, etc. would be clarified more extensively by accelerated progress in this field of research.
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PMID:[Endothelium-derived relaxing factor (EDRF)]. 216 93

The effects of glucose on endothelium-dependent responses and vasoactive prostanoid production were determined by incubating isolated rabbit aortae in control (5.5 or 11 mM) or elevated (44 mM) glucose for 6 h to mimic euglycemic and hyperglycemic conditions. Rings of aortae incubated in elevated glucose, contracted submaximally by phenylephrine, showed significantly decreased endothelium-dependent relaxations induced by acetylcholine compared with the aortae incubated in control glucose. Treatment with indomethacin, a cyclooxygenase inhibitor, or SQ29548, a prostaglandin H2/thromboxane A2 receptor antagonist, restored acetylcholine relaxations of rings in elevated glucose to normal, while these agents had no effect on the relaxation of rings incubated in control glucose. Aortae incubated with mannose (44 mM) as a hyperosmotic control relaxed to acetylcholine normally. The relaxations in response to A23187 and sodium nitroprusside were not different between rings exposed to control and elevated glucose. Radioimmunoassay measurements showed a significant increase in acetylcholine-stimulated release of thromboxane A2 and prostaglandin F2 alpha in aortae with, but not without endothelium incubated with elevated, but not with control glucose. Thus a possible mechanism for endothelium dysfunction in diabetes mellitus is the hyperglycemia-induced increased generation of endothelium-derived vasoconstrictor prostanoids.
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PMID:Elevated glucose promotes generation of endothelium-derived vasoconstrictor prostanoids in rabbit aorta. 231 34

Certain arachidonic metabolites may play a pathogenic role in psoriasis. Platelets are rich sources of 12-hydroxy-eicosatetraenoic acid (12-HETE) and thromboxane A2, mediators of skin inflammation and platelet aggregation, respectively. We have studied untreated psoriatic patients without a history of diabetes mellitus and smoking. In psoriatics, platelet aggregation elicited by thrombin, ADP, and ristocetin was significantly enhanced as compared with healthy adult volunteers. Enhancement of platelet aggregation was detected in patients with both minimal and widespread disease. The formation of 12-hydroxy-5,8,10-heptadecatrienoic acid (HHT), a cyclooxygenase product, and 12-HETE, a 12-lipoxygenase product, was increased in psoriatics with widespread disease but not in those with minimal disease. Formation of 12-HETE was stimulated to a higher degree (125%) than HHT (98%) in psoriasis (P less than 0.05). Addition of platelet-derived 12-HETE to cultured human epidermal keratinocytes resulted in a stimulation of the DNA synthesis (68% at 10(-7) M). These data suggest that platelet activation occurs in psoriasis, and that release of inflammatory and mitogenic compounds by activated platelets may play a role in the pathophysiology of psoriasis. Whether enhanced platelet aggregation in psoriasis is associated with occlusive vascular disease needs further investigation.
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PMID:Increased aggregation and arachidonic acid transformation by psoriatic platelets: evidence that platelet-derived 12-hydroxy-eicosatetraenoic acid increases keratinocyte DNA synthesis in vitro. 243 57

Endothelial cell functions regulating fetal hemodynamics and placental perfusion are modulated by metabolites of arachidonic acid, in particular derivatives of cyclooxygenase such as prostaglandins. We utilized an in vitro system to study the possible role of the vascular endothelium in the pathogenesis of chronic placental insufficiency. Cellular growth and prostaglandin metabolism were investigated in cultured umbilical vein endothelial cells from mothers exposed to risk factors such as smoking and diabetes mellitus during pregnancy. The study comprised cells from smoking (n = 18) and diabetic mothers (n = 5) compared to non-smoking, non-diabetic controls (n = 20). Endothelial cells from smoking and diabetic mothers grew less readily than did control cells. The synthesis of the prostaglandins PGI2 and PGE2, both potent vasodilators and platelet aggregation inhibitors, was significantly reduced in endothelial cells from smoking mothers and from mothers suffering from diabetes of various stages. Thus, reduced prostaglandin synthesis may be a cause of impaired placental perfusion in high risk pregnancies. Our data suggest that prostaglandins may play an important role in the etiology and pathogenesis of chronic placental insufficiency.
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PMID:[Functional differentiation of the vascular endothelium in high risk pregnancies]. 249 34

14C-Arachidonic acid uptake was measured in platelets obtained from 15 insulin-dependent diabetic and 17 control subjects and in 12 streptozotocin-diabetic and 21 control rats. The 14C-arachidonic acid uptake, expressed as pmol/10(8) platelets/min, mean +/- SEM, was significantly higher in platelets from diabetic subjects (2.80 +/- 0.23) and diabetic rats (1.73 +/- 0.20) than in the control subjects (2.29 +/- 0.15) and the control rats (1.35 +/- 0.08). No significant correlations were found between arachidonic acid uptake and glucose, total cholesterol or triglyceride plasma levels in either rats or humans. Arachidonic acid uptake was inhibited by indometacin but not by nordihydroguaiaretic acid, in diabetic as well as in control subjects. The present results suggest that the increased arachidonic acid uptake by platelets from insulin-dependent diabetic patients and streptozotocin-diabetic rats depends on their increased platelet arachidonic acid utilization through the cyclooxygenase pathway.
Diabetes Res Clin Pract 1989 Jun 20
PMID:Increased arachidonic acid uptake by platelets from insulin-dependent diabetics and diabetic rats. 250 69


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