Exercise provides direct biphasic cardioprotection via manganese superoxide dismutase activation.

Epidemiologic investigations have shown that exercise reduces morbidity and mortality from coronary artery disease. In this study, using a rat model, we attempted to determine whether exercise can reduce ischemic injury to the heart and elucidate a mechanism for the cardioprotective effect of exercise. Results showed that exercise significantly reduced the magnitude of a myocardial infarction in biphasic manner. The time course for cardioprotection resembled that of the change in manganese superoxide dismutase (Mn-SOD) activity. The administration of the antisense oligodeoxyribonucleotide to Mn-SOD abolished the expected decrease in infarct size. We showed that the level of tumor necrosis factor alpha (TNF-alpha) and interleukin 1beta (IL-1beta) increased after exercise. The simultaneous administration of the neutralizing antibodies to the cytokines abolished the exercise-induced cardioprotection and the activation of Mn-SOD. Furthermore, TNF-alpha can mimic the biphasic pattern of cardioprotection and activation of Mn-SOD. An antioxidant completely abolished cardioprotection and the activation of Mn-SOD by exercise or the injection of TNF-alpha as well as exercise-induced increase in TNF-alpha and IL-1beta. The production of reactive oxygen species and endogenous TNF-alpha and IL-1beta induced by exercise leads to the activation of Mn-SOD, which plays major roles in the acquisition of biphasic cardioprotection against ischemia/reperfusion injury in rats.

Methylprednisolone reduces postoperative nausea in total knee and hip arthroplasty.

WHAT IS KNOWN AND OBJECTIVE: Total knee and hip joint replacement has a high risk of postoperative nausea and vomiting (PONV), and steroid cover is used for cases associated with autoimmune diseases. Our aim is to evaluate the antiemetic efficacy of methylprednisolone as steroid cover in patients undergoing the surgery. METHODS: A prospective cohort study design was used. Sixty-eight patients, aged between 20 and 80 years, were scheduled for a standardized general anaesthetic technique. Patients who were given methylprednisolone were assigned as the steroid cover group, and those who were not given methylprednisolone formed the non-steroid cover group. PONV were assessment by direct questioning or spontaneous complaints by patients 1 week after surgery. Postoperative pain was evaluated using Visual Analog Scale (VAS) 1 and 3 days after surgery. RESULTS AND DISCUSSION: The incidence of nausea in the steroid cover group was significantly less than that in the non-steroid cover group (adjusted odds ratio, 0·17, P = 0·021), but there was no significant difference in vomiting between the two groups. Postoperative pain VAS score was not significantly different between groups. WHAT IS NEW AND CONCLUSION: In total knee and hip arthroplasty, methylprednisolone is effective in preventing postoperative nausea; however, higher doses of methylprednisolone may be needed to prevent vomiting.

Wnt/frizzled-2 signaling induces aggregation and adhesion among cardiac myocytes by increased cadherin-beta-catenin complex.

Wingless is known to be required for induction of cardiac mesoderm in Drosophila, but the function of Wnt family proteins, vertebrate homologues of wingless, in cardiac myocytes remains unknown. When medium conditioned by HEK293 cells overexpressing Wnt-3a or -5a was applied to cultured neonatal cardiac myocytes, Wnt proteins induced myocyte aggregation in the presence of fibroblasts, concomitant with increases in beta-catenin and N-cadherin in the myocytes and with E- and M-cadherins in the fibroblasts. The aggregation was inhibited by anti-N-cadherin antibody and induced by constitutively active beta-catenin, but was unaffected by dominant negative and dominant positive T cell factor (TCF) mutants. Thus, increased stabilization of complexed cadherin-beta-catenin in both cell types appears crucial for the morphological effect of Wnt on cardiac myocytes. Furthermore, myocytes overexpressing a dominant negative frizzled-2, but not a dominant negative frizzled-4, failed to aggregate in response to Wnt, indicating frizzled-2 to be the predominant receptor mediating aggregation. By contrast, analysis of bromodeoxyuridine incorporation and transcription of various cardiogenetic markers showed Wnt to have little or no impact on cell proliferation or differentiation. These findings suggest that a Wnt-frizzled-2 signaling pathway is centrally involved in the morphological arrangement of cardiac myocytes in neonatal heart through stabilization of complexed cadherin- beta-catenin.

Population pharmacokinetic analysis of vancomycin in patients with gram-positive infections and the influence of infectious disease type.

OBJECTIVE: To describe the population pharmacokinetics of vancomycin in patients with gram-positive infections and to investigate the influence of type of infectious disease. METHODS: A two-compartment open model was adopted as a pharmacokinetic model. The nonlinear mixed-effects model was used to analyze the population pharmacokinetic models. RESULTS: We propose one general model and one infectious disease type-specific model. The general model showed that vancomycin clearance (CL) was linearly correlated with estimated creatinine clearance (CL(CR)) when CL(CR) was less than 85 mL/min, as expressed by CL(L/h) = 0.0322 x CL(CR) + 0.32. The distribution volumes of the central and peripheral compartment were different in healthy volunteers and patients with gram-positive infections. The infectious disease type-specific model showed that these differences were more pronounced in patients with pneumonia. CONCLUSION: The population pharmacokinetic parameters of vancomycin obtained here can be used to individualize the dosage of vancomycin in institutions with similar patient population characteristics.

Structurally abnormal insulin in a diabetic patient. Characterization of the mutant insulin A3 (Val----Leu) isolated from the pancreas.

We have recently identified a diabetic patient with marked fasting hyperinsulinemia. Family study revealed that the abnormality was an autosomal dominant trait. High-performance liquid chromatography (HPLC) profile of the patient's serum insulin showed that she had an abnormal insulin in addition to a normal insulin. We have purified her insulin(s) from the specimen of her pancreas, which was biopsied during an operation of cholelithiasis. Insulin was also immunologically purified from the serum of her portal vein. The reverse-phase HPLC analysis revealed that the ratios of normal to abnormal insulin in the pancreas, portal vein, and peripheral vein were 5:4, 4:5, and 1:7, respectively. Radioreceptor assay for insulin using guinea pig kidney membrane revealed that the binding activities of the normal component insulin, the abnormal component insulin and her pancreatic insulin containing both components were 100, 5, and 50% of standard human insulin, respectively. The biological activities of the normal component, the abnormal component and her pancreatic insulin to stimulate glucose oxidation in rat adipocytes were found to be 100, 8, and 60% of standard human insulin, respectively. Analysis of amino acid sequences of the abnormal insulin purified from her pancreas strongly suggested the substitution of leucine for valine at the third position of the A chain, A3 (Val----Leu).

Induction of manganese superoxide dismutase in rat cardiac myocytes increases tolerance to hypoxia 24 hours after preconditioning.

Manganese superoxide dismutase (Mn-SOD) is induced in ischemic hearts 24 h after ischemic preconditioning, when tolerance to ischemia is acquired. We examined the relationship between Mn-SOD induction and the protective effect of preconditioning using cultured rat cardiac myocytes. Exposure of cardiac myocytes to brief hypoxia (1 h) decreased creatine kinase release induced by sustained hypoxia (3 h) that follows when the sustained hypoxia was applied 24 h after hypoxic preconditioning (57% of that in cells without preconditioning). The activity and content of Mn-SOD in cardiac myocytes were increased 24 h after hypoxic preconditioning (activity, 170%; content, 139% compared with cells without preconditioning) coincidentally with the acquisition of tolerance to hypoxia. Mn-SOD mRNA was also increased 20-40 min after preconditioning. Antisense oligodeoxyribonucleotides corresponding to the initiation site of Mn-SOD translation inhibited the increases in the Mn-SOD content and activity and abolished the expected decrease in creatine kinase release induced by sustained hypoxia after 24 h of hypoxic preconditioning. Sense oligodeoxyribonucleotides did not abolish either Mn-SOD induction or tolerance to hypoxia. These results suggest that the induction of Mn-SOD in myocytes by preconditioning plays a pivotal role in the acquisition of tolerance to ischemia at a later phase (24 h) of ischemic preconditioning.

Endogenous adenosine inhibits P-selectin-dependent formation of coronary thromboemboli during hypoperfusion in dogs.

The activation of platelets and the formation of neutrophil- platelet conjugates may lead to the development of thromboemboli. We studied whether blockade of adenosine receptors during coronary hypoperfusion may cause thromboemboli via P-selectin-dependent mechanisms in 30 open-chest dogs. When coronary blood flow was reduced to 20% of the control, it was stable at low levels with increases in adenosine levels. When 8-p-sulfophenyltheophylline, an adenosine receptor antagonist, was infused during coronary hypoperfusion, coronary blood flow decreased gradually and approached almost zero 20 min after its administration. Histological examination revealed thromboemboli in the small coronary vessels. During hypoperfusion in the presence of 8-p-sulfophenyltheophylline, the mAb against P-selectin attenuated both the reduction in coronary blood flow and the formation of thromboemboli, and improved contractile and metabolic dysfunction of the myocardium. Flow cytometric analysis indicated that the expression of P-selectin on platelet and neutrophil-platelet adhesion were increased during coronary hypoperfusion, and that both were further augmented by 8-p-sulfophenyltheophylline. Immunohistochemical examination showed no staining of P-selectin in the ischemic myocardium. Adenosine inhibited the thrombin-induced expression of P-selectin on platelet and neutrophil- platelet adhesion via adenosine A2 receptors. Adenosine appears to inhibit the formation of thromboemboli during coronary hypoperfusion by suppressing the expression of P-selectin on platelets and neutrophil-platelet adhesion.

Core I97L mutation in conjunction with P79Q is associated with persistent low HBV DNA and HBs antigen clearance in patients with chronic hepatitis B.

OBJECTIVES: When considering treatment for chronic hepatitis B (CHB), it is important to discriminate between patients with persistent low HBV DNA and patients with active hepatitis, who may proceed to cirrhosis. In this study, we sought to identify mutations in patients expected to have persistent low HBV DNA and ultimately exhibit clearance of hepatitis B surface antigen (HBsAg). METHODS: Serum samples were obtained from 33 CHB genotype C patients, divided based on HBV DNA and alanine aminotransferase (ALT) levels following observation for >2 years: Group A (n=10), transient HBV DNA ≥5.0 log copies/mL and ALT ≥120 IU/L; Group B (n=11), persistent HBV DNA <5.0 and ALT <60; and Group C (n=12), persistent HBV DNA <4.0 and ALT <30. Full-length HBV sequences were compared among groups. Subsequently, 82 patients with CHB were evaluated for the I97L mutation and the additional mutation P79Q. We compared cumulative incidences of persistent low HBV DNA and HBsAg clearance in patients with or without I97L and P79Q by the Kaplan-Meier method. RESULTS: Incidence of Core mutation I97L differed significantly among groups: A, 30% (3/10); B, 36.4% (4/11); C, 83.3% (10/12) (p = 0.021). Cumulative incidences of persistent low HBV DNA and HBsAg clearance were significantly higher in patients with I97L than in those with wild-type I97 (p = 0.003 and p = 0.016, respectively), and even higher in those with P79Q. CONCLUSIONS: In patients with CHB, measurement of I97L and additional mutation P79Q would be useful for predicting persistent low HBV DNA, normal ALT, and HBsAg clearance.

Functional role of c-Src in gap junctions of the cardiomyopathic heart.

Given the essential role played by gap junctions in the coordination of cardiac muscle contraction, it is plausible that down-regulation of gap junctional conduction is in part responsible for the contractile dysfunction observed in hypertrophied and failing hearts. In the present study, we analyzed the expression and function of the gap junction protein, connexin43, in the ventricular myocardium of hereditary cardiomyopathic, Syrian BIO 14.6 hamsters. Immunoprecipitation and immunoblot analyses revealed that levels of tyrosine phosphorylated connexin43 were increased in BIO 14.6 hamsters at the late stage of congestive heart failure. Furthermore, the increased tyrosine phosphorylation was correlated with increased c-Src activity. The functional consequences of tyrosine phosphorylation of connexin43 in gap junction were assessed using transfected cells expressing constitutively active c-Src. It was found that constitutively active c-Src diminished propagation of Ca(2+) waves in HEK293 cells and reduced gap junctional conductance between pairs of cardiac myocytes. We, therefore, conclude that during the progression of cardiac dysfunction in the cardiomyopathic heart, gap junctional communication is reduced via c-Src-mediated tyrosine phosphorylation of connexin43.

Role of phasic dynamism of p38 mitogen-activated protein kinase activation in ischemic preconditioning of the canine heart.

Although ischemic stress, including ischemic preconditioning (IP), activates p38 mitogen-activated protein kinase (MAPK), the relationship between p38 MAPK activation and the underlying cellular mechanisms of cardioprotection by IP is not verified in vivo. We examined the effects of the selective p38 MAPK inhibition on the cardioprotective effect of IP in the open-chest dogs. The coronary artery was occluded 4 times for 5 minutes, separated by 5 minutes of reperfusion (IP) followed by 90 minutes of occlusion and 6 hours of reperfusion. We infused SB203580 into the coronary artery during IP and 1 hour of reperfusion, during IP alone, and during sustained ischemia in the IP group. p38 MAPK activity markedly increased during IP but did not additionally increase at the onset of ischemia and was even attenuated at 15 minutes of sustained ischemia, and heat-shock protein (HSP) 27 was phosphorylated and translocated from cytosol to myofibril or nucleus without affecting total protein level at the onset of ischemia compared with the control group. SB203580 treatment (1 micromol/L) only during IP blunted the infarct size limitation by IP (37.3+/-6.3% versus 7.4+/-2.1% in the IP group, P:<0.01) and attenuated either phosphorylation or translocation of HSP27 during IP. Although the SB203580 treatment throughout the preischemic and postischemic periods had no significant effect on infarct size (33.3+/-9.4%) in this model, treatment with SB203580 only during ischemia partially mimicked the infarct size limitation by IP (26.8+/-3.5%). Thus, transient p38 MAPK activation during ischemic preconditioning mainly mediates the cardioprotection followed by HSP27 phosphorylation and translocation in vivo in the canine heart.

Liver stiffness measurement using acoustic radiation force impulse elastography in hepatitis C virus-infected patients with a sustained virological response.

BACKGROUND: Acoustic radiation force impulse (ARFI) elastography is a non-invasive method for measuring liver stiffness. However, there are no reports evaluating the value of ARFI elastography for liver fibrosis in chronic hepatitis C patients with a sustained virological response (SVR). AIM: To investigate the diagnostic performance of ARFI elastography for the assessment of liver fibrosis in hepatitis C virus (HCV) infected patients with an SVR. METHODS: In this prospective study, we enrolled 336 patients: 121 HCV patients with an SVR (44.6% women) and 215 patients with HCV (47.9% women). ARFI elastography measurements of all patients were performed on the same day of liver biopsy. RESULTS: The diagnostic accuracies, expressed as areas under the receiver operating characteristic curves for ARFI elastography, in HCV patients with an SVR and those in patients with HCV were 0.818 and 0.875 for the diagnosis of significant fibrosis (≥F2), 0.909 and 0.888 for the diagnosis of severe fibrosis (≥F3), and 0.981 and 0.890 for the diagnosis of liver cirrhosis (F4), respectively. The optimum cut-off values for ARFI elastography were 1.26 m/s for ≥F2, 1.31 m/s for ≥F3 and 1.49 m/s for F4 in HCV patients with an SVR. The liver stiffness values were lower in patients with SVR compared with those in patients with HCV at the same stage of fibrosis. The liver stiffness values were affected by the necroinflammatory activity and the time after SVR. CONCLUSION: Acoustic radiation force impulse elastography is an acceptable method for predicting the severity of fibrosis in patients with hepatitis C virus and a sustained viral response.

Involvement of cytokines in the mechanism of whole-body hyperthermia-induced cardioprotection.

BACKGROUND: Hyperthermia increases cardiac tolerance to ischemia/reperfusion injury and activates manganese superoxide dismutase (Mn-SOD), an intrinsic radical scavenger, in myocardium in a biphasic manner. Tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) induced a biphasic cardioprotection that corresponded to the activation of Mn-SOD. However, a direct association between Mn-SOD activation in myocardium and the acquisition of tolerance to ischemia/reperfusion injury induced by hyperthermia and the involvement of the cytokines in the signal transduction pathway for the hyperthermia-induced cardioprotection have not yet been elucidated. METHODS AND RESULTS: Hyperthermia was induced in anesthetized rats by placement in a temperature-controlled water bath. At 0.5 and 72 hours after hyperthermia, ischemia was induced by occlusion of the left coronary artery for 20 minutes, followed by reperfusion for 48 hours. Inhibition of the increases in Mn-SOD content and activity 72 hours after hyperthermia by the administration of antisense oligodeoxynucleotides to Mn-SOD abolished the expected decrease in myocardial infarct size. The simultaneous administration of neutralizing antibodies to TNF-alpha and IL-1beta before hyperthermia abolished the biphasic cardioprotection and increase in Mn-SOD activity. CONCLUSIONS: The increase in Mn-SOD activity mediated through the production of TNF-alpha and IL-1beta by whole-body hyperthermia is important in the acquisition of early- and late-phase cardioprotection against ischemia/reperfusion injury in rats.

Calcineurin inhibitor attenuates left ventricular hypertrophy, leading to prevention of heart failure in hypertensive rats.

BACKGROUND: There is controversy regarding the contribution of calcineurin activation to the development of pressure-overload left ventricular (LV) hypertrophy and heart failure. The aim of this study was to explore whether the inhibition of calcineurin may prevent the transition to heart failure in hypertensive rats and, if so, to clarify in which developmental stage of LV hypertrophy calcineurin plays a key role. METHODS AND RESULTS: Dahl salt-sensitive rats placed on an 8% NaCl diet from the age of 7 weeks (hypertensive rats) were randomized to no treatment (n=6) or treatment with the calcineurin inhibitor FK506 (1 mg x kg(-1) x d(-1)) from 8 weeks (FKE, n=7) or from 17 weeks (FKL, n=7). Rats placed on a 0.3% NaCl diet were defined as control rats (n=6). The administration of FK506 from 8 weeks attenuated, although it did not block, LV hypertrophy observed in the untreated rats and prevented the transition to heart failure. The development of LV fibrosis, however, was not attenuated by the administration of FK506 from 8 weeks. The administration of FK506 from 17 weeks brought no benefit for cardiac remodeling or LV function and failed to prevent heart failure. CONCLUSIONS: Calcineurin inhibition, if started from the initial stage of pressure overload, attenuated the development of LV hypertrophy without any effect on LV fibrosis and prevented the transition to heart failure. The activation of calcineurin is involved in the development of LV hypertrophy but not of LV fibrosis, and this involvement may be crucial at the initial stage.

Nifedipine-induced coronary vasodilation in ischemic hearts is attributable to bradykinin- and NO-dependent mechanisms in dogs.

BACKGROUND: Dihydropyridine calcium channel blockers protect endothelial cells against ischemia and reperfusion injury, suggesting that nifedipine may increase the in vivo cardiac NO level and thus coronary blood flow (CBF) in ischemic hearts. We tested this hypothesis. METHODS AND RESULTS: In open-chest dogs, coronary perfusion pressure (CPP) was reduced in the left anterior descending coronary artery so that CBF decreased to one third of the control level, and thereafter CPP was maintained constant (103+/-8 to 43+/-3 mm Hg, n=9). We obtained fractional shortening (FS) and lactate extraction ratio (LER) as indices of regional myocardial contraction and metabolism. Both FS (26.4+/-2.1% to 6.7+/-2.0%, n=9, P<0.001) and LER (32+/-6% to -37+/-5%, n=9, P<0.001) showed a decrease when CPP was reduced. After intracoronary infusion of nifedipine (4 microgram. kg(-1). min(-1)), CBF increased from 30+/-1 to 48+/-4 mL. 100 g(-1). min(-1) (P<0.01) without a change of CPP (n=9). Both FS (14.0+/-1.9%, n=9) and LER (-9+/-7%, n=9) also increased (P<0.01). Nifedipine increased the difference in the level of metabolites of NO (nitrate+nitrite; 9+/-3 to 25+/-5 nmol/mL, n=9, P<0.01) and bradykinin (22+/-5 to 58+/-4 pmol/mL, n=9, P<0.01) between coronary venous and arterial blood. L-NAME (an NO synthase inhibitor) or HOE-140 (a bradykinin receptor antagonist) attenuated (P<0.05) the increase in CBF (29+/-3 and 35+/-2 mL. 100 g(-1). min(-1), n=5 each), FS (4.8+/-0.6% and 6.9+/-1.7%, n=5 each), LER (-47+/-8% and -35+/-9%, n=5 each), and nitrate+nitrite (3+/-2 and 8+/-4 nmol/mL, n=5 each) due to nifedipine infusion. CONCLUSIONS: These results indicate that the calcium channel blocker nifedipine mediates coronary vasodilation and improves myocardial ischemia through both bradykinin/NO-dependent and -independent mechanisms.

Cardioprotective effect afforded by transient exposure to phosphodiesterase III inhibitors: the role of protein kinase A and p38 mitogen-activated protein kinase.

BACKGROUND: Phosphodiesterase III inhibitors (PDEIII-Is) improve the hemodynamic status of heart failure via inotropic/vasodilatory effects attributable to the increase in intracellular cAMP level. Direct cardioprotection by PDEIII-Is and its underlying mechanisms, however, have not been identified. We tested the infarct size-limiting effect of PDEIII-Is and the roles of cAMP, protein kinase (PK) A, PKC, and mitogen-activated protein kinase (MAPK) families in open-chest dogs. Methods and Results-- Milrinone, olprinone (PDEIII-Is), or dibutyryl-cAMP (db-cAMP) was injected intravenously 30 minutes before 90-minute ischemia, followed by 6 hours of reperfusion. Olprinone was also examined with an intracoronary cotreatment with a PKA inhibitor (H89), a PKC inhibitor (GF109203X), an extracellular signal-regulated kinase kinase (MEK) inhibitor (PD98059), or a p38 MAPK inhibitor (SB203580) throughout the preischemic period. Either PDEIII-Is or db-cAMP caused substantial hemodynamic changes, which returned to control levels in 30 minutes. Collateral flow and percent risk area were identical for all groups. Both PDEIII-Is and db-cAMP increased myocardial p38 MAPK activity during the preischemic period, which was blocked by H89, but not by GF109203X. Both PDEIII-Is and db-cAMP reduced infarct size (19.1+/-4.1%, 17.5+/-3.3%, and 20.3+/-4.8%, respectively, versus 36.1+/-6.2% control, P<0.05 each). Furthermore, the effect of olprinone was blunted by either H89 (35.5+/-6.4%) or SB203580 (32.6+/-5.9%), but not by GF109203X or PD98059. H89, GF109203X, PD98059, or SB203580 alone did not influence infarct size. CONCLUSIONS: Pretreatment with PDEIII-Is has cardioprotective effects via cAMP-, PKA-, and p38 MAPK-dependent but PKC-independent mechanisms in canine hearts.

Radioimmunoassay of glibenclamide.

A specific, sensitive, and simple radioimmunoassay was developed for the oral hypoglycemic drug glibenclamide, N-4-[2-(5-chloro-2-methoxy-benzamide)-ethyl]-benzenesulfonyl-N'-cyclohexylurea. Antiserum against glibenclamide was obtained from rabbits immunized with an antigen prepared by conjugating the diazonium salt of N(p-amino-benzamidoethyl)-benzenesulfonyl-N'-cyclohexylurea to bovine serum albumin through the diazocoupling. [3H]glibenclamide was used as a tracer. Dextran-coated charcoal was used to separate bound and free [3H]glibenclamide in the reaction mixture. The radioimmunoassay is able to determine as little as 25 pg of glibenclamide directly in plasma without the need for extraction. The antiserum used for the assay was highly specific for glibenclamide, and did not cross-react with two known major metabolites of glibenclamide. Comparable values of glibenclamide in dog plasma were obtained by radioimmunoassay and liquid chromatography. Plasma concentrations of glibenclamide in diabetic patients on glibenclamide treatment can be determined by radioimmunoassay, and the method has been applied to the routine assay of clinical samples. This radioimmunoassay seems to be useful for monitoring plasma glibenclamide concentrations.

Identification of nucleotide substitution in gene encoding [LeuA3]insulin in third Japanese family.

We previously described a new case of abnormal insulinemia in Japan. In one allele, nucleotide-sequence analysis revealed a substitution in the codon for the third position of insulin A chain (GTG----TTG), causing [LeuA3]insulin. This point mutation is the same as that found in insulin Wakayama. In this family, the mutant insulin allele cosegregated with an 850-base pair PvuII allele of the hypervariable region 5'-flanking the insulin gene.

Effects of dietary treatment on serum insulin and proinsulin response in newly diagnosed NIDDM.

Serum proinsulin is disproportionately elevated both in the basal state and after an oral glucose load in non-insulin-dependent diabetes mellitus (NIDDM). However, there is no detailed information about the effect of glycemic control on this abnormality. We investigated the effect of glycemic control by dietary treatment on serum proinsulin level in the basal state and in response to an oral glucose load. Ten NIDDM patients (7 men and 3 women), aged 19-60 yr, with mean (+/- SD) body mass index of 28 +/- 6 kg/m2 (range 21-42 kg/m2) and normal renal and liver function were studied. Before and after dietary therapy (25-30 kcal/kg ideal body wt), 100-g oral glucose tolerance tests were performed. Proinsulin was measured with our proinsulin-specific antiserum, which recognizes the connecting site of the B-chain of insulin and C-peptide. After dietary treatment, fasting plasma glucose decreased from 197 +/- 35 to 113 +/- 18 mg/dl (P less than .001). Both serum insulin and proinsulin decreased (insulin from 15 +/- 8 to 10 +/- 4 microU/ml, P less than .02; proinsulin from 31 +/- 18 to 13 +/- 5 pM, P less than .02), and the molar ratio of proinsulin to insulin also tended to decrease (from 0.321 +/- 0.08 to 0.24 +/- 0.10, P less than .10). Insulin response to oral glucose increased after dietary treatment, whereas proinsulin response did not change, resulting in a significant decrease in the molar ratio of the area under the curve of proinsulin to insulin after glucose load (from 0.28 +/- 0.12 to 0.13 +/- 0.07, P less than .001).(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of the early time courses of the release of insulin that follow injections of tetragastrin, tolbutamide, xylitol, and glucose into the pancreatic artery of dogs.

The early time courses of insulin release were studied by injecting insulinotropic substances directly into a dog's pancreatic artery. Blood samples from the pancreatic vein were collected every five seconds continuously over 90 seconds and were assayed for their insulin concentrations. Injections were repeated two to five times, with intervals of 30 minutes. Insulin release was stimulated within one minute after injection of each of tetragastrin, tolbutamide, xylitol, and glucose, but the time courses of the release of insulin were different with different stimulants: Tetragastrin and tolbutamide increased insulin release faster than did glucose; xylitol produced a slower insulin release than did glucose. The slower insulin-releasing effects of glucose and xylitol than the other agents would be compatible with the theory that their metabolism is required to cause release of insulin, but it is also possible that the glucoreceptor mechanism may require a longer lag time than the other receptor mechanisms for the perception and transfer of the signal to release insulin.

Reduced urinary insulin clearance in patient with abnormal insulinemia.

We recently reported a new case of abnormal insulinemia with LeuA3 insulin. Herein, we measured urinary insulin clearance during oral glucose tolerance tests in proband with abnormal insulinemia (44-yr-old female), three affected family members, two unaffected family members, two other hyperinsulinemic patients with obesity, five non-insulin-dependent diabetic patients, and five normal control subjects. Urinary insulin-to-creatinine clearance ratio in the proband and her affected family members was 0.22 X 10(-3) +/- 0.07 (mean +/- SD, n = 4) and was markedly reduced compared with those of other groups: 1.73 X 10(-3) in two unaffected family members, 2.77 X 10(-3) in two other hyperinsulinemic patients with obesity, 2.99 X 10(-3) +/- 1.48 in five non-insulin-dependent diabetic patients, and 2.54 X 10(-3) +/- 0.67 in five normal control subjects. In contrast, urinary C-peptide clearance in these groups was not significantly different from controls. Binding of immunopurified insulins extracted from urine of the patients with abnormal insulinemia to guinea pig kidney membrane was slightly decreased (71% of standard insulin), in contrast with the observation that serum insulin of the proband had much less receptor-binding activity. Reverse-phase HPLC analysis of the immunopurified insulin of the proband revealed that the ratios of normal insulin to abnormal insulin were 8:3 in urine and 1:7 in serum, respectively. These results suggest that excretion of abnormal insulin in urine is much less than that of normal insulin.