Angioscopic evaluation of thrombi in the culprit coronary lesions in patients with acute myocardial infarction.

The purpose of this study was to evaluate intracoronary thrombi in the culprit lesions in patients with acute myocardial infarction (AMI) by angioscopy, and to compare them with clinical and angiographic features. We angioscopically observed the culprit coronary lesions in 66 patients with AMI (55 males and 11 females, 63.9+/-15.4 years old) just before interventional therapy. Thrombi were observed in 42 of 66 lesions (64%), namely, red thrombi in 16, mixed thrombi in 15, white thrombi in 11. In patients with complete obstruction (TIMI grade 0 and I), red thrombi were more frequently observed than mixed or white thrombi. On the other hand, in patients with incomplete obstruction (TIMI grade II and III), white thrombi were more frequently observed than the others. Angiographically, haziness and filling defect were significantly more frequently observed in patients with red thrombi than the others (p<0.05). The distance from proximal side branch to thrombi tended to be longer in patients with red thrombi than the others. The time from onset of AMI tended to be longer in patients with white thrombi than the others. These results suggest that blood flow may be an important determinant of thrombi characterization.

[Effect of ethanol injection in tracheal large cell carcinoma--a case report].

A 66-year-old woman was admitted with dyspnea. A tracheal tumor was found by bronchofiberscopy, and histological examination revealed large cell carcinoma. The tumor obstructed nearly 90% of her tracheal lumen, so we performed intratumoral ethanol injection. The tumor became almost completely necrotic, and obstruction of her airway markedly improved. No serious complication was found. Intratumoral ethanol injection was very effective and safe in this case. This is the fifth report of undifferentiated carcinoma of the trachea in Japan.

Modulation of insulin action by fasting: a study using a phosphodiesterase activation system in rat fat cells.

Fat cells from control and 72 h fasted rats were incubated with increasing concentrations of insulin at 37 degrees C for 10 min. A crude microsomal fraction from these cells was used for the determination of phosphodiesterase activity. Specific activities of the enzyme in fat cells from the fasted rats were higher at overall insulin concentrations. In the fasted rats the curve shifted to the left at the lower concentrations of insulin and the half-maximal dose was lower than in the controls. Specific binding of insulin to the receptor was increased at the lower concentrations of insulin in fat cells from the fasted rats and Scatchard analysis of the data revealed that the change was due to an increase in binding affinity rather than that in receptor number per cell. Therefore, it is feasible that there is a good correlation with alteration of insulin sensitivity and insulin binding. The net amount of maximal response to insulin assessed as enzyme activity per cell was markedly decreased with fasting, however, this seems to be due to a decrease in absolute amount of the enzyme per cell. Since the maximal activation of the enzyme expressed as a percent of the basal remained unchanged, the steps between insulin receptor and the phosphodiesterase may not be altered under these conditions.

Lactic acidosis and hypoglycemia associated with acute leukemia.

A 42-year-old man was admitted because of episodic attack of general malaise. He was lethargic and had a severe lactic acidosis and hypoglycemia. Blood chemistry and endocrinological data were normal. Glucose administration led to an improvement in the hypoglycemia but not the lactic acidosis. At autopsy, there was a massive infiltration of leukemic cells in both kidneys and in liver. Phosphoenolpyruvate carboxykinase, pyruvate carboxylase and glucose-6-phosphatase activities in patient's liver were much the same as in the control liver, but fructose-1, 6-diphosphatase activity was slightly reduced. Since circulatory failure was absent, type B lactic acidosis has to be considered. Since hypoglycemia was associated with acidosis, the severe lactic acidosis in our patient may have been due to an overproduction of lactic acid as well as to an impaired hepatic gluconeogenesis in the presence of leukemic cells.

Effects of changes in serum insulin in response to dexamethasone and adrenalectomy on insulin-sensitive phosphodiesterase in rat fat cells.

The effects of dexamethasone administration and adrenalectomy on insulin-sensitive phosphodiesterase were studied in rat fat cells. Isolated fat cells were incubated at 37 degrees C for ten minutes or without insulin. A crude microsomal fraction prepared by differential centrifugation was used for the determination of phosphodiesterase level. With dexamethasone treatment (400 micrograms/kg/day) for seven days, specific activity of the enzyme and its sensitivity (ED50) to insulin were decreased, as was the maximal responsiveness to insulin. Under conditions of adrenalectomy, the specific activity and the sensitivity (ED50) were increased while the maximal responsiveness to insulin was decreased. Following dexamethasone treatment specific insulin binding was decreased, and after adrenalectomy it increased. These findings were attributed to changes in the number of insulin receptors per cell rather than to changes in affinity. Alterations in insulin sensitivity (ED50) of the enzyme seemed to be due to alterations in insulin binding to the receptor. The reduction in maximal insulin responsiveness suggested postreceptor defects in both experimental groups. The mechanism related to alterations in the specific activity was not thoroughly clarified; however, serum insulin levels may specifically affect the enzyme activity.

Activation of insulin-sensitive phosphodiesterase by lectins and insulin-dextran complex in rat fat cells.

Membrane-bound low-Km cAMP phosphodiesterase was activated by concanavalin A, wheat germ agglutinin, and insulin-dextran complex under conditions of incubation with intact rat fat cells. Concanavalin A rapidly stimulated the enzyme activities and maximum was reached at 10 to 15 minutes. As little as 10 micrograms/mL concanavalin A activated the enzyme and a maximal response was obtained at 100 to 300 micrograms/mL, but concanavalin A and wheat germ agglutinin were less potent than insulin. Specific saccharide inhibitors completely abolished activation of the enzyme by lectins, but had no effect on the activation of insulin. Digestion of fat cells with 1 mg/mL trypsin for 15 minutes completely inhibited activation of the enzyme by insulin. However, concanavalin A was less sensitive to trypsinization. The insulin-dextran complex, which did not penetrate the plasma membrane, activated the enzyme and was one tenth as effective as the native insulin. These results suggest that the insulin-like actions of these lectins are provoked through coupling with the carbohydrate moiety on the cell membrane close to insulin receptors.

Is somatostatin a true local inhibitory regulator of insulin secretion?

Pancreatic somatostatin was depleted after oral administration of cysteamine to rats, yet the B-cells in the isolated islets were morphologically and functionally intact. Compared with islets from the rats not given cysteamine, the somatostatin-depleted islets released larger amounts of insulin during 1 h of incubation by glucose or 3-isobutyl-1-methylxanthine stimulation. Therefore, the possibility that pancreatic somatostatin may locally regulate the inhibitory effects of insulin secretion has to be considered.

Augmented gastrin responses in diabetic patients with vagal neuropathy.

We evaluated serum gastrin responses to a test meal in normal subjects and diabetic patients with or without vagal neuropathy. Vagal neuropathy was defined as a heart rate variation during deep breathing of less than 9 beats/min. Forty-three percent (54 out of 124) of the diabetic patients had abnormal heart rate variation, compared with 5% (3 out of 53) of the normal subjects. Serum gastrin responses to a test meal were examined in 17 normal subjects, 20 out of 70 diabetic patients without vagal neuropathy and 17 out of 54 diabetic patients with vagal neuropathy. Meal-stimulated gastrin levels were significantly higher in the diabetic patients with vagal neuropathy than in the normal subjects, while the findings in the diabetic patients without vagal neuropathy were similar to those in normal subjects. These data suggest that augmented gastrin responses are due to vagal denervation induced by autonomic neuropathy.

Increased sensitivity of insulin-sensitive phosphodiesterase to insulin in fat cells from streptozotocin diabetic rats.

The effects of insulin on insulin-sensitive phosphodiesterase were investigated in fat cells from control and streptozotocin diabetic rats. Isolated cells were incubated at 37 C for 10 min, with and without insulin. A crude microsomal fraction prepared by differential centrifugation was assayed for phosphodiesterase activity. The enzyme activities in diabetic rats were higher at 0-1 nM insulin than in control rats. The dose-response curve of insulin was biphasic and of the convex type in both groups. In diabetic rats, the curve shifted to the left, and half-maximal stimulation was obtained at 0.06 nM insulin compared with 0.16 nM insulin in control rats. Kinetic analyses of the enzyme from diabetic rats revealed much the same findings as obtained in the controls. Specific binding of insulin in fat cells from control and diabetic rats was 3% and 4.9%/2 X 10(5) cells, respectively, at 24 C for 60-min incubation. Scatchard analysis indicates that the overall binding affinity in diabetic cells was greater than that in the control cells. These results suggest that the insulin effector system related to phosphodiesterase activation is intact and has an increased sensitivity in fat cells from streptozotocin diabetic rats; there is also a good correlation with alteration of insulin binding to its receptors.

Somatostatin and insulin secretion from pancreatic islets: studies on the effect of high K+, 9-aminoacridine and valinomycin.

We attempted to determine whether a decrease in the potassium permeability of the D cell membrane plays a role in the stimulus-secretion coupling, as it does in the pancreatic B cell. Elevation in the extracellular potassium concentration from 5.5 to 16.5 mM, or 0.2 mM 9-aminoacridine, which decreases potassium permeability in plasma membrane, stimulated the release of somatostatin as well as insulin from the isolated rat pancreatic islets. Valinomycin (1 microM), a potassium ionophore inhibited the secretion in response to high glucose, high extracellular potassium or 9-aminoacridine. These findings indicate that a reduction in potassium permeability in the D cell membrane, as induced by glucose or other stimulants, may be a major step in secretion of somatostatin.

An assessment of the new NIH diagnostic criteria for diabetes mellitus according to insulin response in a 75 g oral glucose tolerance test and levels of hemoglobin AIC.

This study reviews the new diagnostic criteria for diabetes mellitus proposed by NIH. We measured insulin levels during 75 g oral glucose tolerance test (75 g OGTT) and hemoglobin AIC levels in patients diagnosed as having impaired glucose tolerance (IGT) or non-insulin dependent diabetes (NIDDM) according to the NIH criteria. In a 75 g oral glucose tolerance test, there was no significant difference in insulin-glucose ratio between nonobese IGT and nonobese NIDDM who had fasting blood glucose levels of less than 120 mg/dl (NIDDM-A group). However, in nonobese NIDDM with fasting blood glucose higher than 120 mg/dl (NIDDM-B group), the insulin-glucose ratio was significantly lower than in the IGT or NIDDM-A group. The NIDDM-B group had a higher hemoglobin AIC levels than the IGT and NIDDM-A groups, with no significant difference between the levels of the two latter groups. These observations suggest that the impairment in the function of pancreatic B cells and the state of chronic hyperglycemia are the same in IGT & NIDDM-A groups. Therefore, the NIH standards do not appear refined enough to truly differentiate between IGT and nonobese NIDDM with fasting blood glucose of less than 120 mg/dl.

Hypotonic activation of insulin-sensitive phosphodiesterase in rat fat cells.

The effect of hypotonic treatment on the low Km membrane-bound cyclic AMP phosphodiesterase was investigated. Isolated fat cells obtained from Sprague-Dawley rats were incubated at 37 degrees C with an without 2 nM insulin. A crude microsomal fraction prepared by differential centrifugation was suspended in a hypotonic buffer at 4 degrees C, with and without protease inhibitors. Following solubilization from the particulate fraction, hypotonic treatment stimulated the phosphodiesterase in a time-dependent manner. Among the protease inhibitors, E-64, leupeptin and antipain were effective in preventing hypotonic activation of the enzyme. The release of the enzyme from the particulate fraction was partially inhibited by antipain. Kinetic analysis of the enzyme from hypotonic activation was much the same as that of the enzyme from the isotonic buffer. These results suggest that hypotonic activation of the phosphodiesterase may be the result of stimulation of an endogenous thiol protease of lysosomal origin.

Effects of sulfonylureas on membrane-bound low Km cyclic AMP phosphodiesterase in rat fat cells.

The effects of sulfonylureas and a biguanide on membrane-bound low Km cyclic AMP phosphodiesterase and lipolysis were examined in rat fat cells. Pharmacologically active sulfonylureas, such as tolbutamide (10 mM), acetohexamide (10 mM) and glibenclamide (200 microM) activated the phosphodiesterase when incubated with fat cells and suppressed lipolysis induced by isoproterenol. However, neither of these actions was observed in the presence of a pharmacologically inactive sulfonylurea, carboxytolbutamide (10 mM) and a biguanide, buformin (500 microM). Tolbutamide (0.5-10 mM) activated the enzyme, concentration dependently, and this manner of activation appears to coincide with that of the suppressive effect on the lipolysis. The time course of the enzyme activation was similar to that seen with insulin. Km, optimal pH and sensitivity to temperature of the enzyme from tolbutamide-treated cells were the same as those of the enzyme from control and insulin-treated cells. Direct incubation of the enzyme from control cells with tolbutamide did not affect the activity, while as little as 10 microM 3-isobutyl-1-methylxanthine markedly inhibited the enzyme. Tolbutamide continued to activate the enzyme in cells in which insulin receptor had been destroyed by trypsin-pretreatment. These results are compatible with the idea that the enzyme activated by sulfonylurea and that activated by insulin may be the same species of phosphodiesterase and that the antilipolytic action of sulfonylurea may be mediated by the activation of the enzyme which does not occur through the insulin receptor.

Pancreatic somatostatin contents in spontaneously diabetic KK and non-obese diabetic (NOD) mice.

Alterations in the somatostatin (SRIF)-, insulin- and glucagon-containing cells were examined in two strains of spontaneously diabetic mice, KK and newly inbred non-obese diabetic (NOD) mice, using radioimmunoassay and immunohistochemical methods. The total pancreatic content and concentration of SRIF was decreased in male KK mice compared to their male controls aged 12-18 weeks. These results were consistent with the immunohistochemical findings. Pancreatic glucagon concentration and number of glucagon-containing cells were also decreased in KK mice, but pancreatic insulin concentrations were increased in KK mice. On the other hand, NOD mice aged 12-38 weeks within 15 days after onset of diabetes had increased concentrations of pancreatic SRIF. The pancreatic islets in NOD mice were decreased both in number and in size and were characterized by lymphocyte infiltration. SRIF-containing cells occupied the major part of the endocrine cells of the islets. Insulin-containing cells significantly decreased in number, but the number of glucagon-containing cells was fairly well preserved. These results and previous work concerning obob and dbdb mice indicate a parallel relationship between pancreatic SRIF and glucagon. The pancreatic glucagon thus as well as the pancreatic insulin may be an important determinant of pancreatic SRIF concentration in these diabetic animals.

Effects of dithiothreitol on insulin-sensitive phosphodiesterase in rat fat cells.

Dithiothreitol activates the low-Km membrane-bound cyclic AMP phosphodiesterase when incubated with the enzyme in a cell-free system. To investigate the mechanism of its activation, we studied the effect of protease inhibitors. Isolated fat cells obtained from Sprague-Dawley rats were incubated in Krebs-Henseleit Hepes buffer, pH 7.4, at 37 degrees C with and without insulin (2 nM, 10 min). A crude microsomal fraction prepared by differential centrifugation was suspended in 0.25 M sucrose containing 10 mM Tes buffer, pH 7.5, with and without 2 mM dithiothreitol and protease inhibitors at 4 degrees C for 48 h. Dithiothreitol stimulated the phosphodiesterase, in a time-dependent manner. As little as 0.02 mM dithiothreitol activated the enzyme, and the maximally effective dose was 2-10 mM. Among the various protease inhibitors tested, antipain, leupeptin, chymostatin and E-64 were the most effective in preventing activation of the enzyme by dithiothreitol. Antipain also inhibited release of the enzyme from the bound fraction. These results suggest that activation of the low-Km phosphodiesterase by dithiothreitol may be provoked by stimulation of an endogenous thiol protease.

Effect of glucose on somatostatin secretion from isolated pancreatic islets of normal and streptozotocin-diabetic rats.

Pancreatic somatostatin (SRIF) secretion was examined using the RIA described in earlier paper. Ten isolated rat pancreatic islets were incubated for 30 min in 1 ml Krebs-Ringer bicarbonate buffer. Glucose (5.6 mM) caused a small but significant increase of SRIF secretion. The maximal secretion rate was observed at 16.7 mM glucose, and the half-maximal rate was seen at about 9.7 mM. Islets preincubated with 16.7 mM glucose released higher levels of SRIF and insulin during the subsequent incubation with 16.7 mM glucose than did islets preincubated with 2.8 mM glucose. Glucose-induced SRIF secretion was suppressed by epinephrine, but beta-adrenergic stimulation (epinephrine and phentolamine) produced an increase in SRIF secretion. Islets taken from rats 2 days after streptozotocin administration released minimal amounts of insulin. Basal and glucose-induced SRIF secretion from these islets, which had relatively unchanged SRIF contents and D cell numbers, equaled SRIF secretion from control rat islets. Islets taken from rats 6 weeks after streptozotocin administration, however, had increased SRIF content and D cell numbers, and they oversecreted SRIF. We conclude that pancreatic SRIF secretion can be induced by glucose and modulated by catecholamines and preexposure to high glucose, and the duration and severity of diabetes may be an important determinant of the changes in pancreatic D cell structure and function.

Effect of calcium on the secretion of somatostatin and insulin from pancreatic islets.

Calcium ionophore A23187 (20 micrometer) evoked the secretion of somatostatin (SRIF) as well as insulin from isolated rat pancreatic islets in a medium containing a relatively low concentration of calcium (0.9 mM) and a low concentration of glucose (5.5 mM). A high level of extracellular calcium (7.5 mM) also had a stimulatory effect on SRIF and insulin release. On the other hand, in the presence of high glucose (16.7 mM), A23187 had different effects on D and B cells; insulin release was markedly suppressed by A23187, but SRIF secretion was significantly enhanced. A high concentration of glucose (16.7 mM) did not stimulate SRIF secretion at low extracellular calcium concentration (0.25 mM), at which level insulin release is significantly enhanced. These findings indicate that calcium may play an important role in the regulation of the secretion of SRIF as well as insulin and suggest that the B and D cells differ in their sensitivity to the calcium ion.