Enhanced insulin response to oral glucose load in patients with angina pectoris associated with ST segment elevation in the absence of epicardial coronary arterial obstruction.

The authors treated 10 patients with microvascular angina (MVA) manifesting angina pectoris, ST segment elevation suggestive of transmural myocardial ischemia, and no epicardial arterial obstruction. Since such patients frequently showed abnormal responses to oral glucose loading, the authors investigated the glucose and insulin responses to glucose loading in 10 MVA patients, 25 patients with vasospastic angina (VAP), 25 patients with effort angina (EAP), and 25 control subjects. Insulinogenic index, peripheral insulin activity [= 10(4)/(peak glucose x insulin at glucose peak)], glucose area, and insulin area were calculated. The MVA group included two patients with impaired glucose tolerance and two newly diagnosed diabetic patients. These proportions were similar to those in the VAP and EAP groups. Glucose levels at 30 to 180 min and insulin levels at 90 to 120 min in the MVA group were higher than in the control group. Peak glucose, glucose area, peak insulin, and insulin area were higher in the MVA group than in the control group (p<0.01). Those in the VAP and EAP groups were also higher. Insulin/glucose ratio at 120 min was higher, peripheral insulin activity, lower, in the disease groups than in the control group (p<0.05). The MVA patients showed a hyperglycemic and hyperinsulinemic response to oral glucose loading, as did the patients with EAP and VAP. Enhanced insulin response to oral glucose loading may also contribute to the pathogenesis of MVA.

Hereditary methemoglobinemia due to cytochrome b5 reductase deficiency in blood cells without associated neurologic and mental disorders.

Following the observation of two fraternal patients without neurologic symptoms, but with hereditary methemoglobinemia due to cytochrome b5 reductase deficiency in erythrocytic and nonerythrocytic cells, a familial study of their paternal and maternal relatives was undertaken. Ferrihemoglobin reductase activities in erythrocytes from the two patients were found to be impaired, and cytochrome b5 reductase activities in platelets and leukocytes were essentially absent. Any deficiencies of the enzyme activities seemed not to be found in nonhematopoietic cells. The enzyme activities in blood cells derived from the parents and some of their paternal and maternal family members showed levels intermediate between those of the patients and those of the normal control, which seemed to be heterozygous. The present cases did not belong to either the classic erythrocytic or the generalized type, and their enzyme deficiency was found rather to be restricted to their blood cells and not associated with neurologic and mental disorders. A necessity of diagnosis by tissues other than blood cells is discussed for a severe form of generalized-type hereditary methemoglobinemia with associated neurologic and mental disorders.