Simultaneous surgical correction of a common atrium and impure flutter

We performed surgical correction and treatment of a common atrium and chronic impure flutter using a computerized mapping system in a 49-year-old man. A reentrant circuit was observed to exist around the left atrial appendage. In contrast to the regular activation in the left atrium, the activation sequence of the right atrium was extremely chaotic. Cryolesions were applied to the area of the reentrant pathway. After the operation, sinus rhythm was restored.

Tumor necrosis factor receptors in the pituitary cells

To clarify the site and mode of action of tumor necrosis factor (TNF) in the pituitary, we studied the effects, binding sites of TNF and its receptor mRNA in the two types of mouse pituitary-derived cell lines, AtT-20, ACTH-producing cells and TtT/GF, folliculo-stellate (FS)-like cells. First, we examined the expression of TNF receptor mRNA in these cells. Using Northern blot analyses with radiolabeled cDNA to murine TNF receptor p60 and p80 mRNAs as probes, we identified both types of mRNA in the poly(A)-containing RNA prepared from AtT-20 cells and p60 TNF receptor mRNA from TtT/GF. The identified mRNA were compatible in size with those detected in the immune-competent cells. Next, we studied the TNF-binding sites on these cells. Scatchard plot analysis of the significant binding of [125I]TNF revealed a single type of binding site with a Kd (dissociation constant) of 210 pM and 131 binding sites/cell on AtT-20. Similarly on TtT/GF, [125I]TNF showed 353 binding sites/cell with a Kd of 900 pM. [125I]TNF binding on both types of cells competed with TNF and lymphotoxin (TNF beta) in an equimolar fashion. Third, TNF stimulates ACTH synthesis in AtT-20 cells, while TNF increases immunoreactive interleukin (IL)-6 release from TtT/GF cells. These findings demonstrate that AtT-20 and TtT/GF cells are equipped with fully functional TNF receptor system, and suggest that ligand of the receptor, TNF alpha and/or TNF beta, can modulate ACTH synthesis and release as a direct hormonal effector on corticotrophs or indirect modulator through another paracrine mediator, such as IL-6 from FS cells.

CMO I deficiency caused by a point mutation in exon 8 of the human CYP11B2 gene encoding steroid 18-hydroxylase (P450C18)

Corticosterone methyloxidase I (CMO I) deficiency is an autosomal recessive disorder of aldosterone biosynthesis. To determine further the molecular genetic basis of CMO I deficiency, a patient of Turkish origin that suffered from CMO I deficiency was studied. Nucleotide sequencing of the PCR-amplified exons from the genomic DNA of this patient revealed a single point mutation CTG (leucine) CCG (proline) at codon 461 in exon 8 of CYP11B2, which is involved in the putative heme binding site of steroid 18-hydroxylase (P450(C18)). The expression study using a cDNA introducing the point mutation revealed that the amino acid substitution totally abolishes the P450(C18)p3 enzyme activities required for conversion of 11-deoxycorticosterone to aldosterone, even though the mutant product was detected in the mitochondrial fraction of the transfected cells. These results suggest that this point mutation causes CMO I deficiency.

Infective endocarditis. Considerations for the timing of surgical intervention and type of infecting microorganism

To determine the appropriate timing for surgical intervention in infective endocarditis (IE), we evaluated 24 patients (17 males, 6 females, with one included twice) who underwent surgical intervention for IE of native valves (NVE, n = 21) and prosthetic valves (PVE, n = 3) between January 1989 and September 1994. The mean age was 41 +/- 13 years (range 6 to 64 years). The most common infective organisms were Staphylococcus (33% of NVE) and Streptococcus (19% of NVE), with five NVE patients (24%) negative for blood culture. The PVE patients showed a different pattern of infecting organisms, with Enterococcus in one and Pseudomonas in another. From the resected valve culture and pathological findings, 12 patients were in the active stage at operation. Two in-hospital deaths occurred for a mortality rate of 8.7% (2/23). Further, surgical interventions were performed earlier with Staphylococcal infections than with Streptococcal infections, because hemodynamic compromise presented more progressively in the former. Also resected valve cultures and the pathological findings showed that a persistent infectious process existed in many cases of Staphylococcal infection in spite of intensive antibiotic therapy. In conclusion, we suggest that internists make referrals for surgical intervention for patients with NVE or PVE as early as possible in the active stage of infection.

Effects of M16209, a new antihyperglycemic agent, on insulin sensitivity in vivo: euglycemic clamp studies in rats

The effects of M16209 (1-(3-bromobenzo[b]furan-2-ylsulfonyl)hydantoin) on the in vivo insulin sensitivity of rats were studied by euglycemic clamp methods after 1 week of administration (10 or 100 mg/kg/d). M16209 increased both the glucose infusion rate (GIR) and metabolic clearance rate (MCR) of 3-[3H]-glucose, but did not suppress hepatic glucose output. M16209 also increased the [3H]-2-deoxyglucose utilization rate, rate of incorporation of [14C]-glucose into glycogen, and glycolytic flux in the soleus and red gastrocnemius muscles, but not in the extensor digitorum lungus and white gastrocnemius muscles. M16209 affected neither the [3H]-2-deoxyglucose utilization rate nor the rate of incorporation of [14C]-glucose into lipids in epididymal adipose tissue. In the soleus muscle, M16209 decreased glucose-6-phosphate (G6P) and fructose-6-phosphate (F6P) content, but did not affect fructose-1,6-bisphosphate (F-1,6-BP) content. Moreover, M16209 increased glycogen synthase-I activity and fructose-2,6-bisphosphate (F-2,6-BP) content in the soleus muscle. These results suggest that M16209 increases insulin-stimulated glucose uptake in peripheral tissues, particularly oxidative muscles, through potentiation of insulin action on glycogen synthesis and glycolysis. Glycogen synthase and phosphofructokinase (PFK) appear to be major targets of the action of M16209.

Amelioration of insulin resistance in genetically obese rodents by M16209, a new antidiabetic agent

Improvement of metabolic disorders by M16209 (1-(3-bromobenzofuran-2-ylsulfonyl)hydantoin), an antidiabetic agent, was studied in genetically obese Zucker fa/fa rats and C57BL/6J ob/ob mice. In fa/fa rats oral administration of M16209 (30 and 100 mg/kg/day) for 7 days dose dependently improved hyperinsulinemia without affecting body weight. Oral glucose loading (2 g glucose/kg body weight) after 10 days of administration to fa/fa rats revealed that M16209 significantly improved glucose tolerance both 30 and 60 min after glucose loading, but did not affect preload serum glucose levels. At one day after 13 days of administration of M16209, the serum levels of triglyceride, total cholesterol and free fatty acid were clearly lower in treated fa/fa rats than those in untreated rats. In C57BL/6J ob/ob mice, M16209 given for 28 days at doses of 30 and 100 mg/kg/day improved hyperinsulinemia, hyperglycemia and hypercholesterolemia without affecting body weight. In a hyperinsulinemic euglycemic clamp study in fa/fa rats, administration of M16209 for 7 days at a dose of 100 mg/kg/day significantly normalized the decreased metabolic clearance rate but did not show any effect on the augmented hepatic glucose output. These findings demonstrate that improvement of metabolic disorders in genetically obese rodents by M16209 is due to amelioration of insulin resistance in peripheral tissues.

[Left free wall rupture complicating acute myocardial infarction--a case report of surgical success by a new modified method]

The success rate of surgical treatment for blowout type free wall rupture of the left ventricle following myocardial infarction has been reported as 4 to 24%. A 64-year-old woman was admitted to our hospital for inferior acute myocardial infarction with cardiogenic shock. In the catheter laboratory, her hemodynamics disclosed electro-mechanical dissociation, and we had to perform an emergent operation there. In order to preserve left ventricular volume and reduce the risk of bleeding, we adopted a modified method using both patch and felt strip sandwich methods which obtained favorable result. The patient was sent to a rehabilitation hospital on the 43rd post operative day because of a mild cerebral complication and she is now doing well with only a slight speaking disturbance at a follow-up period of 10 months.

Atrial natriuretic peptide blunts arterial baroreflex in spontaneously hypertensive rats

We and other laboratories have reported that arterial baroreflex-mediated control of heart rate is blunted in spontaneously hypertensive rats (SHR) compared with normotensive controls. Recently, we reported that atrial natriuretic peptide (ANP) microinjected into the caudal nucleus tractus solitarii of SHR further blunts this defect. The present study tested the hypothesis that ANP modulates arterial baroreflex-mediated control of sympathetic nervous system activity. Nine-week-old, male SHR (n = 29) and normotensive Wistar-Kyoto control rats (n = 24) were instrumented for microinjection into the caudal nucleus tractus solitarii and for direct measurement of arterial blood pressure, heart rate, and lumbar sympathetic nervous system activity. After urethane- and alpha-chloralose-induced induced anesthesia, arterial baroreflex-mediated control of heart rate and lumbar sympathetic nerve activity was assessed during phenylephrine- (5 to 40 micrograms.kg-1.min-1) induced increases and sodium nitroprusside- (15 to 300 micrograms.kg-1.min-1) induced decreases in mean blood pressure before and after microinjection of ANP (50 ng) or monoclonal antibody to ANP (0.55 micrograms) into the caudal nucleus tractus solitarii. ANP reduced and the antibody enhanced the sensitivity of baroreflex-mediated control of both heart rate and lumbar sympathetic nerve activity in SHR but not in Wistar-Kyoto controls (P < .05). Arterial baroreflex sensitivity was unchanged with control microinjections of vehicle or mouse IgG in SHR. These data suggest that endogenous ANP in the caudal nucleus tractus solitarii may contribute to the development and/or maintenance of hypertension in SHR by blunting baroreflex-mediated control of sympathetic nervous system activity.

The insulin gene promoter. A simplified nomenclature

The tools of molecular biology have rapidly expanded our knowledge of how β-cells regulate insulin gene expression. As this work has progressed in parallel in different laboratories, alternate nomenclature systems have been developed to describe the functionally important elements of the insulin gene. This jumble of names is confusing to those outside the field and intimidating to neophytes. Therefore, we have agreed to a simple, uniform set of names for the major insulin gene promoter elements.

[Cryosurgical ablation of the atrioventricular conduction system--experimental study for the determination of the appropriate ablation site and the long term follow-up results with clinical application]

In a series of experimental studies in dogs, we determined the exact site for the disruption of the atrioventricular conduction system by cryosurgical ablation which does not disturb the intraventricular conduction. The long-term symptomatic effects were evaluated in 9 patients with supraventricular tachycardia. In a total of 15 adult mongrel dogs, a thoracotomy was performed under pentobarbital anesthesia that was maintained during the procedure with artificial ventilation and cardiopulmonary bypass. The body temperature was maintained at 37 degrees C and throughout each experiment, the ECG was recorded by the conventional limb lead method while monitoring and recording the His bundle potentials from the catheter-electrode introduced via the internal carotid artery. The location in which the maximum His bundle potential was recorded was determined by intraoperative His bundle mapping through the right atrial incision. Cryoablation was performed by using -60 degrees C probes with a 5 mm tips. In 5 dogs (experiment A), we compared the effect of cryoablation at 2 different points on the interatrial septum, which were either 10 mm (10 mm point) or 5 mm (5 mm point) away from the site of the largest His bundle potential to the direction of the coronary sinus ostium. The two ablations were performed successively at 20 minute intervals. A second group consisting of 10 dogs, received cryoablation only at the 5 mm point (experiment B). In experiment A, atrioventricular block (AV block) was inconsistently achieved following cryoablation at the 10 mm point, whereas at the 5 mm point, the procedure was 100% successful in obtaining AV block without affecting the QRS morphology or H-V interval. In experiment B, we confirmed the reliability of the 5 mm point. Following cryoablation at the 5 mm point, coagulation necrosis in the region from the AV node to the penetrating portion of the His bundle were observed by pathological examination, however, the damage was only mild at the branching portion of the His bundle. Cryoablation was performed at the 5 mm point in 9 subjects. In all of these cases, complete AV block was successfully produced to terminate the tachycardias. The R-R interval of the escape rhythm in these patients gradually prolonged, and stabilized at 1500-1600 ms 3 years following the operation. In the long-term electrophysiological studies, all subjects had A-H block, and there were no subjects with prolonged H-V intervals observed. We conclude that cryoablation at the 5 mm point is an appropriate and effective choice for the treatment of supraventricular tachycardias.

Portal hypertension associated with anticardiolipin antibodies in a case of systemic lupus erythematosus

A 26-year-old man with systemic lupus erythematosus (SLE) and a history of acute myocardial infarction developed portal hypertension accompanied by abnormal liver function and esophageal varices. As his clinical course suggested the possibility of antiphospholipid syndrome, a titer of anticardiolipin antibody (aCL) was serially measured using an enzyme immunoassay with beta 2-glycoprotein I as a cofactor. The titer of aCL increased with the development of portal hypertension, and promptly decreased with the improvement of liver function just after corticosteroid therapy. The long-term course in this case suggests that aCL may cause portal hypertension associated with SLE.

Inborn errors of aldosterone biosynthesis in humans

Corticosterone methyl oxidase (CMO) type I and type II deficiencies are inborn errors at the penultimate and ultimate steps in the biosynthesis of aldosterone in humans. Recently, steroid 18-hydroxylase (P450C18), or aldosterone synthase (P450aldo), was shown to be a multifunctional enzyme catalyzing these two steps of aldosterone biosynthesis, i.e., the conversion of corticosterone to 18-hydroxycorticosterone and the subsequent conversion of 18-hydroxycorticosterone to aldosterone. This observation suggests that CMO I and CMO II deficiencies are derived from two different mutations in the P450C18 gene (CYP11B2). To elucidate whether or not this is the case, we performed molecular genetic studies on CYP11B2 of both types of patients. Nucleotide sequence analysis has indicated that the gene of CMO I deficient patients is completely inactivated by a frameshift to form a stop codon due to a 5-bp nucleotide deletion in exon 1. Sequence analysis of CYP11B2 of CMO II deficient patients has revealed two point mutations, CGG-->TGG (Arg181-->Trp) in exon 3 and GTG-->GCG (Val386-->Ala) in exon 7. CYP11B1, the gene for steroid 11 beta-hydroxylase (P45011 beta) which was previously postulated to be the target for CMO II deficiency, is not impaired in these two types of patients. Expression studies using the corresponding mutant cDNAs have shown that CMO I deficient patients are null mutants with a complete lack of P450C18 whereas CMO II deficient patients are leaky mutants with an altered P450C18 activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Insulin sensitivity and glycemic control before and after parathyroidectomy in a diabetic patient with familial multiple endocrine neoplasia type 1

We treated a diabetic patient with familial multiple endocrine neoplasia type 1 (MEN 1) who had undergone total pancreatoduodenectomy. The patient received insulin and showed signs of symptomatic primary hyperparathyroidism (PHPT). The insulin requirement to control blood glucose before and after parathyroidectomy was compared by using an artificial pancreas. The insulin infusion rate during the day and at night was reduced to about one-third and half, respectively, after parathyroidectomy with autotransplantation of parathyroid tissues into the forearm. The daily insulin dose was reduced from 36 units to 14 units 2 weeks after surgery, and glycemic control showed further improvement 2 months after surgery with the same dose of insulin for up to 6 months. These observations suggest that insulin sensitivity increases after surgical correction of PHPT.

Endocrine disorders and diabetes in Japan

The frequency of glucose intolerance including diabetes and IGT in endocrine diseases was compared between Japan and foreign countries. It was revealed that the frequency of diabetes in endocrine diseases is generally higher in Japan than in foreign countries. In addition, plasma insulin response to glucose was exaggerated in Cushing's syndrome with glucose intolerance, but was impaired in acromegaly and pheochromocytoma with glucose intolerance.

Glucose effectiveness in two subtypes within impaired glucose tolerance. A minimal model analysis

To clarify the event that is involved in the pathogenesis of impaired glucose tolerance (IGT), we studied 15 individuals with IGT and 15 subjects with normal tolerance using the minimal model approach. Our IGT subjects were characterized by normal insulin secretory responses to oral glucose and mild impairments in insulin sensitivity (SI) and glucose effectiveness (SG) at basal and zero insulin. Next, we classified our IGT subjects into two subpopulations: one with normal insulin sensitivity (SI: 0.92 +/- 0.11 x 10(-4) min-1.pmol/l-1 and the other with insulin resistance (SI:0.31 +/- 0.06 x 10(-4)min-1.pmol/l-1, P < 0.05). The populations did not differ with respect to body mass index and fasting plasma glucose level. Basal plasma insulin level was higher in the insulin-resistant group (84.8 +/- 23.3 pmol/l) than in the insulin-sensitive group (48.7 +/- 6.8 pmol/l), but the difference was not statistically significant. The absolute insulin secretory responses to oral glucose were significantly higher in the resistant group (83,205 +/- 17,787 pmol/l x min) than in the sensitive group (24,727 +/- 3,591 pmol/l x min, P < 0.01), whose absolute responses were similar to those of normal control subjects (24,576 +/- 2,767 pmol/l x min). No significant difference was observed in SG between the resistant (0.016 +/- 0.002 min-1) and sensitive (0.013 +/- 0.002 min-1, P > 0.05) type of IGT, but SG was significantly type of IGT, but SG was significantly decreased in both groups compared with normal control subjects (0.023 +/- 0.002 min-1, P < 0.05-0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

A novel substrate for insulin-sensitive serine/threonine kinase in intact cells

We have studied insulin-stimulated threonine phosphorylation of cellular proteins by immunoblotting and immunoprecipitation using antiphosphothreonine antibody (anti-P-Thr). A 50-kilodalton protein (p50) was found to be greatly phosphorylated on threonine residues upon insulin stimulation in intact rat hepatoma cells (Fao) and Chinese hamster ovary cells overexpressing human insulin receptor (CHO-HIR). Insulin induced threonine phosphorylation of this protein in a dose-dependent manner, with an ED50 of 3-6 x 10(-9) M. The 50-kilodalton phosphoprotein (pp50) was detectable 20 min after exposure of the cells to insulin, and phosphorylation reached a maximum after 90 min. Immunoprecipitation of pp50 with anti-P-Thr required extraction of the cellular proteins with sodium dodecyl sulfate and dithiothreitol, and subcellular fractionation of the cells revealed that pp50 is present in the membrane fraction, implying that pp50 is a protein integrated into the membrane component in the cells. Tryptic phosphopeptide mapping of the pp50 was distinct from that of the insulin receptor beta-subunit. Phosphoamino acid analysis of the pp50 demonstrated that insulin increased phosphorylation, mainly of threonine and moderately of serine, whereas pp50 did not contain phosphotyrosine. Cycloheximide, a protein synthesis inhibitor, did not affect the insulin-induced appearance of pp50 in the cells. pp50 was not detectable in A431 cells and KB cells stimulated by epidermal growth factor. These data suggest that p50 is a novel endogenous substrate for insulin-sensitive serine/threonine kinase in intact cells.

Human somatostatin receptor, SSTR2, is coupled to adenylyl cyclase in the presence of Gi alpha 1 protein

Somatostatin has been shown to exert diverse biological effects in various tissues. Recently, the human genes encoding five subtypes of somatostatin receptor (SSTR1-SSTR5) were cloned. Among these subtypes SSTR2 is present in many endocrine tumors as well as normal tissues and may mediate the effects of somatostatin analog, SMS201-995. In this study, we have investigated the intracellular effect of SSTR2 stably expressed in Chinese hamster ovary cells. Somatostatin-14 does not affect the forskolin stimulated cAMP formation when human SSTR2 is expressed in CHO cells, which lack internal Gi alpha 1 protein. However, somatostatin-14 inhibits the adenylyl cyclase in a dose dependent and pertussis toxin-sensitive manner when human SSTR2 is co-expressed with Gi alpha 1 in CHO cells. These results indicate that human SSTR2 is functionally coupled to Gi alpha 1 protein but not to Gi alpha 2 or Gi alpha 3 when expressed in CHO cells.

Functional analysis of the cell-specific enhancer in the human proopiomelanocortin gene by beta-galactosidase histochemical staining

Nucleotide sequences responsible for the cell-specific expression of the human proopiomelanocortin (POMC) gene were analyzed by histochemical staining of beta-galactosidase in culture cells transfected with chimeric genes containing the 5'-flanking regions of the human POMC gene fused to the Escherichia coli lacZ gene. The chimeric genes were stably introduced into various culture cells, including AtT-20 cells, which express the endogenous mouse POMC gene. Whereas the control gene containing the cytomegalovirus enhancer was expressed in all cell lines tested, only AtT-20 cells supported the efficient transcription of the gene containing 2.9 kb of the human POMC 5'-flanking region. These results indicate that the stable transfection-expression system utilizing the histochemical detection of the gene expression is a useful method for the analysis of cell-specific gene expression. These results have also confirmed that the trans-acting factors in mouse AtT-20 cells interact with the human POMC gene promoter region and activate the transcription of the gene. Deletion analysis has demonstrated that the profiles of the transcriptional activity of the various human POMC-lacZ fusion genes are similar to those of the rat POMC gene described previously. Comparison of the human and the rat 5'-flanking sequences revealed close homology in several regions, which might be involved in the efficient transcription of the POMC gene in AtT-20 cells.