Regulation of phosphorylation of Gi2 alpha protein controls the secretory response to isoproterenol in rat parotid tissues

Treatment of rat parotid tissues with 1 microM isoproterenol (IPR) for 10 min caused a 60% decrease in pertussis toxin (IAP)-catalyzed ADP-ribosylation of Gi alpha and resulted in supersensitivity of amylase secretion from the tissues. However, conversely, IPR treatment for 30 min caused a 40% increase in IAP-catalyzed ADP-ribosylation of Gi alpha, coupled with desensitization of amylase secretion. No changes in Gs function were observed in IPR-induced phenomena. Pretreatment with okadaic acid induced enhancement of the supersensitivity of amylase secretion and disappearance of the desensitization. These phenomena were accompanied with decreases in IAP-catalyzed ADP-ribosylation of Gi alpha. IPR treatment for 30 min caused a 50% decrease in phosphorylation of Gi2 alpha immunoprecipitated with anti-G protein antiserum (AS/7) from [32P]Pi-labeled cells, but such treatment for 10 min caused a 40% increase in phosphorylation in the cells pretreated with okadaic acid. Phosphorylation and dephosphorylation of immunoprecipitates with AS/7 by protein kinase A (PKA) and alkaline phosphatase caused decreases and increases in IAP-catalyzed ADP-ribosylation, respectively, indicating the presence of PKA-mediated phosphorylation sites on Gi2 alpha. Thus, the control of the phosphorylation of Gi2 alpha is of importance and relevance in the regulation of biological processes and cellular responses.

Soluble adenylyl cyclase from Spodoptera frugiperda (Sf9) cells. Purification and biochemical characterization

An insect ovarian cell, Spodoptera frugiperda (Sf9), has been widely used to express recombinant proteins, including adenylyl cyclase, as a host cell in the baculovirus expression system. We report the presence and characterization of a soluble adenylyl cyclase (sAC) distinct from a membrane-bound form of adenylyl cyclase (mAC) that is also present in Sf9 cells. sAC was purified 3,500-fold to near homogeneity; a single band at 25 kDa on SDS-polyacrylamide gel electrophoresis correlated well with adenylyl cyclase catalytic activity. The purified enzyme had a catalytic activity of 0.1 micromol/min.mg and the Km of 0.55 mM for the substrate ATP. In contrast to mAC, sAC was heat-stable. Enzymatic activity of sAC was not stimulated by forskolin and was inhibited by salts at high concentrations. sAC utilized both manganese- and magnesium-ATP as substrate. Di- or triphosphate-containing nucleotides, such as GTP and GDP, as well as pyrophosphate, noncompetitively inhibited sAC. Our data suggest that the physical and biochemical characteristics of sAC are different from those of mAC in Sf9 cells as well as from those of other known forms of adenylyl cyclase in animal cells; sAC in Sf9 cells may constitute a new member of adenylyl cyclase found in animals.

Beta-adrenoceptor desensitization during the development of canine pacing-induced heart failure

1. The goal of this review is to emphasize four major points regarding the development of catecholamine desensitization in heart failure (HF). 2. Catecholamine desensitization occurs prior to the development of HF (i.e. after 1 day of rapid pacing, physiological responses to beta-adrenoceptor stimulation are depressed by over 50%, yet no evidence of HF is observed for 3-4 weeks of rapid pacing). 3. Multiple mechanisms in the beta-adrenoceptor cascade are involved. In HF there are decreases in beta 1-adrenoceptors, high affinity beta-adrenoceptors, adenylyl cyclase activity and messenger RNA and increases in Gi. 4. Not all mechanisms appear simultaneously (i.e. early decreases occur in high affinity beta-adrenoceptors and adenylyl cyclase; late increases in Gi and decreases in beta-adrenoceptor density evolves). 5. Mechanisms distal to cAMP generation also play a role (i.e. alterations in ryanodine receptor binding and excitation-contraction coupling also occur).

[Cardiac arrhythmias caused by electrolyte imbalance]

Cardiac arrhythmias are known to be caused by many factors. Among them, electrolyte imbalance is the most important because of electrical activity of the heart is composed of transmembrane fluxes of Na+, Ca2+ and K+. In this review article, we describe the effects of high or low concentrations of these electrolytes on the active and passive electrical properties of the membrane in the cardiac tissues, and the mechanisms by which these electrolytes cause abnormal impulse formation and conduction in the heart. Antagonism and synergism of electrolytes and pathological conditions such as digitalis intoxication and ischemia are discussed with respect to not only cardiac electrophysiology but also cellular metabolism. A pathophysiological role of Mg2+ to maintain normal excitation and conduction of the heart is also pointed out.

[Clinical evaluation of 99mTc-HMPAO labeled leukocyte imaging in ulcerative colitis]

Inflammatory imaging using 99mTc-HMPAO-labeled mixed leukocytes was assessed for use in treating 11 cases diagnosed as ulcerative colitis: 10 cases with total colitis and 1 with left-sided colitis. They consisted of 8 patients with relapse-remitting type and 3 with chronic continuous type. Radionuclide abdominal images were obtained at 1 hr, 4 hr and 24 hr after intravenous injection of 200 MBq prepared 99mTc leukocytes. Obvious colonic activity noted at 4 hr served as the basis for positive comparative criterion in the present study. The diagnostic efficacy of radionuclide imaging was compared with endoscopic findings (based on Matts' classification) and the clinical manifestations as reference. The sensitivity and specificity of this imaging were 83.3% and 85.7%, respectively, these values being consistent with endoscopic findings and clinical manifestations at sites of disease activity. All of positive images changed to negative after treatment by leukocyte apheresis or glucocorticoid. Based on these results, 99mTc leukocyte imaging can be used to accurately evaluate severity and treatment response in ulcerative colitis. Leukocytes may be closely related to the pathogenesis of ulcerative colitis.

Acute myeloblastic leukaemia in a cow

A myeloblastic leukaemia was found in a 6-year-old Holstein cow. Although macroscopical lesions were not found in parenchymal organs, the animal had many neoplastic cells in the peripheral blood, bone marrow, lymph nodes, and spleen. By light microscopy most neoplastic cells appeared to be agranular blast cells, but some cells contained acidophilic granules and stained positively for naphthol AS-D chloroacetate esterase and lysozyme. Ultrastructural examination revealed that many of the blast cells had a few peroxidase-positive granules and corresponded to early promyelocytes.

[Single-dose toxicity studies of prulifloxacin (NM441) in mice, rats and dogs and the active metabolite (NM394) in rats]

Single-dose toxicity studies of prulifloxacin, a new antibacterial agent, were conducted in mice, rats and dogs. In addition, a single-dose toxicity study of (+/-)-6-fluoro-1-methyl-4-oxo-7- (1-piperazinyl)-4H-[1,3]thiazeto[3,2-a]quinoline- 3-carboxylic acid (NM394), an active metabolite of prulifloxacin, was performed in rats. Prulifloxacin was administered orally, intraperitoneally (i.p.) or subcutaneously (s.c.) to mice and rats, and orally to dogs. NM394 was administered intravenously (i.v.) to rats. When prulifloxacin was administered orally or s.c., LD50 values were more than 5000 mg/kg in both sexes of mice and rats; when it was administered i.p., LD50 values were 1757 mg/kg in male mice, 1652 mg/kg in female mice, 915 mg/kg in male rats, and 1076 mg/kg in female rats. The lethal doses of this drug were more than 5000 mg/kg in both sexes of dogs by the oral route. The LD50 values of NM394 were 226 mg/kg in male rats and 238 mg/kg in female rats by the i.v. route. In mice, the major clinical signs observed following the administration of prulifloxacin were sedation, oligopnea, abnormal gait, piloerection, closed eye and tremor by the i.p. route and a scab at the site of injection by the s.c. route; in rats, decreased spontaneous locomotor activity by any of the three routes, oligopnea, lacrimation, hypothermia, piloerection and abnormal gait by the i.p. route, and a scab at the site of injection by the s.c. route; and in dogs, vomiting, reddening of the skin, and loose stool by the oral route. When NM394 was administered i.v., rats showed clonic convulsion and dyspnea. The site of injection was hyperemic, swollen and necrotic. Mice showed a decrease in body weight or an inhibition in weight gain when prulifloxacin was administered i.p. and rats showed the same effects when prulifloxacin or NM394 was administered by any of the above-mentioned routes. Macroscopic findings detected following the i.p. administration of prulifloxacin in mice were pale color of the liver and spleen, thickening of the liver, and adhesion of intra-abdominal organs; and in rats, hydrothorax, congestion and edema of the lung, adhesion of intra-abdominal organs, swelling of the kidney accompanied by fine yellowish-white foci, and atrophy of the testis. When NM394 was administered i.v. to rats, congestion of the lung was macroscopically observed.

Extensive polymorphism of ABO blood group gene: three major lineages of the alleles for the common ABO phenotypes

Polymorphism of the ABO blood group gene was investigated in 262 healthy Japanese donors by a polymerase chain reactions-single-strand conformation polymorphism (PCR-SSCP) method, and 13 different alleles were identified. The number of alleles identified in each group was 4 for A1 (provisionally called ABO*A101, *A102, *A103 and *A104 according to the guidelines for human gene nomenclature), 3 for B (ABO*B101, *B102 and *B103), and 6 for O (ABO*O101, *O102, *O103, *O201, *O202 and *O203). Nucleotide sequences of the amplified fragments with different SSCP patterns were determined by direct sequencing. Phylogenetic network analysis revealed that these alleles could be classified into three major lineages, *A/*O1, *B and *O2. In Japanese, *A102 and *B101 were the predominant alleles with frequencies of 83% and 97% in each group, respectively, whereas in group O, two common alleles, *O101 (43%) and *O201 (53%), were observed. These results may be useful for the establishment of ABO genotyping, and these newly described ABO alleles would be advantageous indicators for population studies.

[Prospective randomized trial comparing 1/2 FAM (5-fluorouracil (5-FU) + adriamycin + mitomycin C) versus palliative therapy for the treatment of unresectable pancreatic and biliary tract carcinomas (the 2nd trial in non-resectable patients). Japanese Study Group of Surgical Adjuvant Therapy for Carcinomas of the Pancreas and Biliary Tract]

The efficacy of 1/2 FAM, which consists of 5-fluorouracil (5-FU), adriamycin (ADM) and mitomycin C (MMC), was compared with that of palliative treatment in patients with unresectable pancreatic and biliary tract carcinomas in a multicenter randomized trial. The patients assigned to 1/2 FAM group were treated with 5-FU 200 mg/m2/day IV, ADM 15 mg/m2/day IV and MMC 5 mg/m2/day IV. These 3 drugs were given concurrently as the initial dose within a week after palliative operation, and this regimen was repeated for at least 2 whole courses, at 4-week intervals before the next course of therapy. Those randomized to the control group were subjected to palliative treatment alone. Completely eligible for analysis were 42 cases of the 1/2 FAM group and 41 of the control group. There was no significant difference between the groups with respect to the overall and differentiated survival times according to the tumor sites and the clinical efficacy. As for the duration of 50% inhibition of tumor progression, a significantly better outcome was obtained in 1/2 FAM group. Tumor progression was most significantly inhibited in patients with gallbladder carcinoma. In 1/2 FAM group, tumor reduction was achieved in 1 CR and 2 PR patients. The most frequent adverse reaction was gastrointestinal manifestations, along with diarrhea and alopecia. 1/2 FAM did not contribute to the life prolongation, but inhibited the tumor progression for a significantly longer duration and, to a lesser extent, reduced the tumor size in unresectable pancreatic and biliary tract carcinomas. This regimen is suggested to be useful particularly in the treatment of the latter carcinoma.

[Pharmacokinetics of 99mTc-MAG3 and 131I-OIH: comparative study based on 2 compartment model analysis]

We studied 50 patients with mild to moderate renal dysfunction to compare pharmacokinetics of 99mTc-MAG3 with that of 131I-OIH. After simultaneous bolus injection of both 99mTc-MAG3 and 131I-OIH, 8-point venous blood sampling was performed from 2 to 44 min post injection. Aliquoted plasma samples were counted for radioactivity along with the injected standard to obtain % injected dose/ml plasma for each tracer. Using obtained time-concentration data, classical 2 compartment model analysis was performed for both tracers to obtain various pharmacokinetic parameters, including distribution volumes (Vds), inter-compartmental rate constants, and plasma clearance. In these parameters, Vd of central compartment, Vd at steady state, central to peripheral inter-compartmental rate constant, and plasma clearance were significantly larger for 131I-OIH. In all parameters, significant correlation was found between 99mTc-MAG3 and 131I-OIH. The best correlation was seen in plasma clearance (r = 0.891, p < 0.0001). Plasma clearance ratio (99mTc-MAG3/131I-OIH), however, showed weak but significant negative correlation with serum creatinine, although this correlation was not likely to affect the overall correlation of clearance between 131I-OIH and 99mTc-MAG3. From these results, we confirmed that 99mTc-MAG3 clearance could be used as an alternative to 131I-OIH clearance, although pharmacokinetic behavior of 99mTc-MAG3 was not exactly the same as that of 131I-OIH.

Regulation of type V adenylyl cyclase by PMA-sensitive and -insensitive protein kinase C isoenzymes in intact cells

Abstract Type V adenylyl cyclase (AC) was stably over-expressed in HEK293 cells (293AC-V). Forskolin-stimulated cAMP accumulation in 293AC-V was 5 times as great as that in control cells. PMA, a protein kinase C (PKC) activator, enhanced cAMP accumulation in 293AC-V cells dose-and time-dependently and this enhancement was abolished by staurosporine. Insulin also enhanced cAMP accumulation in 293AC-V cells. Co-transfection of PKC-zeta, but not PKC-alpha, potentiated the effects of insulin. These data suggest that type V AC activity is regulated in cells by PKC isoenzymes through different extracellular stimuli.

Adverse effects of chronic endogenous sympathetic drive induced by cardiac GS alpha overexpression

To study the physiological effect of the overexpression of myocardial Gsalpha (protein levels increased by approximately threefold in transgenic mice), we examined the responsiveness to sympathomimetic amines by echocardiography (9 MHz) in five transgenic mice and five control mice (both 10.3 +/- 0.2 months old). Myocardial contractility in transgenic mice, as assessed by left ventricular (LV) fractional shortening (LVFS) and LV ejection fraction (LVEF) was not different from that of control mice at baseline (LVFS, 40 +/- 3% versus 36 +/- 2%; LVEF, 78 +/- 3% versus 74 +/- 3%). LVFS and LVEF values in transgenic mice during isoproterenol (ISO, 0.02 micrograms/kg per minute) infusion were higher than the values in control mice (LVFS, 68 +/- 4% versus 48 +/- 3%; LVEF, 96 +/- 1% versus 86 +/- 3%; P < .05). Norepinephrine (NE, 0.2 micrograms/kg per minute) infusion also increased LVFS and LVEF in transgenic mice more than in control mice (LVFS, 59 +/- 4% versus 47 +/- 3%; LVEF, 93 +/- 2% versus 85 +/- 3%; P < .05). Heart rates of transgenic mice were higher than those of control mice during ISO and NE infusion. In three transgenic mice with heart rates held constant, LV dP/dt rose by 33 +/- 2% with ISO (0.02 micrograms/kg per minute) and by only 13 +/- 2% in three wild-type control mice (P < .01). NE (0.1 micrograms/kg per minute) also induced a greater effect on LV dP/dt in the three transgenic mice with heart rates held constant compared with three wild-type control mice (65 +/ 8% versus 28 +/- 4%, P < .05). Pathological and histological analyses of older transgenic mouse hearts (16.0 +/- 0.8 months old) revealed hypertrophy, degeneration, atrophy of cells, and replacement fibrosis reflected by significant increases in collagen volume in the subendocardium (5.2 +/- 1.4% versus 1.2 +/- 0.3%, P < .05) and in the cross-sectional area of myocytes (298 +/- 29 versus 187 +/- 12 micron2, P < .05) compared with control mouse hearts. These results suggest that Gsalpha overexpression enhances the efficacy of the beta-adrenergic receptor-Gs-adenylyl cyclase signaling pathway. This in turn leads to augmented inotropic and chronotropic responses to endogenous sympathetic stimulation. This action over the life of the animal results in myocardial damage characterized by cellular degeneration, necrosis, and replacement fibrosis, with the remaining cells undergoing compensatory hypertrophy. As a model, this transgenic mouse offers new insights into the mechanisms of cardiomyopathy and heart failure and provides a new tool for their study.

Excess of rare cancers in Werner syndrome (adult progeria)

The association between genetic disorders and diverse cancers has provided clues for laboratory research into carcinogenesis. Such an opportunity now arises from studies of cancer in Werner syndrome (WRN). Soft-tissue sarcoma (STS) and benign meningioma have been associated with WRN, an autosomal recessive disorder characterized by premature aging, more commonly reported in Japan than elsewhere, in part because of inbreeding. In the literature we found 124 case-reports of neoplasia and WRN from Japan and 34 from outside Japan, 1939-August, 1995. They reveal a greater diversity of neoplasia in WRN than was previously known. In Japanese, there were 127 cancers, 14 benign meningioma, and 5 myeloid disorders, as compared with 30, 7 and 2 respectively in non-Japanese. The ratio of epithelial to non-epithelial cancers was about 1:1 for Japanese and for non-Japanese instead of the usual 10:1. Both series had excess of STS, osteosarcoma, myeloid disorders, and benign meningioma. In addition, the Japanese had an excess of thyroid cancer (20 versus 2 cases in non-Japanese) and melanoma (21 versus 3 cases), including 5 intranasal and 13 of the feet. STS, osteosarcoma, melanoma, and thyroid carcinoma accounted for 57% of all cancer in WRN as compared with 2% expected based on the Osaka population at 25-64 years of age. Multiple tumors were reported in 19 Japanese and 5 non-Japanese. In Japan, nine first-degree relatives had WRN and cancer, six of whom were concordant as to site and/or cell type. The WRN gene has been mapped to chromosome 8p. The high frequency of thyroid cancer and melanoma in Japanese, not found in Caucasians, may be related to a report of linkage disequilibrium with the WRN gene in Japanese but not in Caucasians and to haplotype differences within and between the two races, suggesting multiple independent mutations.

Myocardial ischemia due to vascular systemic amyloidosis: a quantitative analysis of autopsy findings on stenosis of the intramural coronary arteries

A case is reported of a 65 year old man who suffered myocardial ischemia resulting from extensive stenosis of the intramural coronary arteries secondary to systemic vascular involvement by primary amyloidosis. In the myocardium, there were multiple fibrotic foci scattered mainly in the subendocardial region of the ventricle. Intramural coronary arteries were stenotic or occlusive due to amyloid-induced luminal narrowing, but there was no significant stenosis of the epicardial coronary arteries. Quantitative analysis of amyloid deposits in the intramural coronary arteries demonstrated that occlusive arteries were predominant in the surrounding area of myocardial fibrosis, and the extent of coronary stenosis by amyloid deposition was significantly more severe than in hearts of the five control patients who had coronary amyloidosis without myocardial fibrosis. These results indicate that myocardial fibrosis originates from coronary ischemia due to vascular amyloid deposition. This is the first time that the relationship between myocardial lesions and coronary amyloid deposition has been elucidated using histopathologic quantitative analysis.

Concurrent pulmonary arterial dissection and saccular aneurysm associated with primary pulmonary hypertension

We report concurrent pulmonary arterial dissection and saccular aneurysm resulting from primary pulmonary hypertension in a 26-year-old man. The pulmonary trunk was dissected 9 cm along its entire circumference, 3 cm above the pulmonary valvular cusps. In addition, a saccular aneurysm 3.5 cm in diameter had formed at the right pulmonary hilus. Histopathology revealed marked medical degeneration and fragmentation of the elastic laminae in the former lesion and a true aneurysm with attenuation and fragmentation of elastic laminae in the latter. The peripheral vasculature in the lungs showed evidence of increased pulmonary arterial pressure, including plexiform and angiomatoid lesions. We present this unique case and discuss the pathomorphogenesis of these lesions in conjunction with primary pulmonary hypertension.

Influence of cluster formation of acidic phospholipids on decrease in the affinity for ATP of DnaA protein

DnaA protein is the initiator of chromosomal DNA replication in Escherichia coli. We examined the influence of artificial mixed membrane composed of synthetic acidic (phosphate) lipid and basic (ammonium) lipid on the affinity of DnaA protein for ATP. Two sets of acidic and basic lipids with distinguishable numbers of hydrophobic alkyl chains were devised. Synthetic membranes made of the sole acidic lipid but not the basic bilayers inhibited the ATP binding to DnaA protein and stimulated the release of ATP from the ATP-DnaA complex. The basic bilayer-forming compounds served as the matrix for the guest acidic lipids. Acidic lipids dispersed in the basic matrix membrane had little effect on ATP binding and on ATP release. Conversely, acidic lipids forming cluster structures in the mixed artificial membranes inhibited the ATP binding and stimulated the release of ATP. These observations suggest that in mixed lipid bilayers, a cluster structure of acidic lipids seems to be an important parameter to decrease the affinity of DnaA protein for ATP.

Novel insight into molecular mechanism of endotoxin shock: biochemical analysis of LPS receptor signaling in a cell-free system targeting NF-kappaB and regulation of cytokine production/action through beta2 integrin in vivo

Lipopolysaccharide (LPS), a constituent of gram-negative bacteria cell wall, plays an essential role in the pathogenesis of septic shock by generating endogenous mediators such as cytokines, nitrous oxide, superoxide anions, and lipid mediators. In vitro, LPS induces the transcription of a set of genes involved in inflammatory reactions by activating several types of transcription factors, particularly nuclear factor-kappaB (NF-kappaB). An analysis of NF-kappaB activation using a cell-free system demonstated that two pathways converge to activate NF-kappaB; one is staurosporine-sensitive, the other is staurosporine-insensitive and tyrosine kinase-dependent. Furthermore, the latter pathway culminates in IkappaBalpha phosphorylation at serine/threonine residues in its carboxyl-terminal acidic region with dissociation of IkappaBalpha from NF-kappaB, thereby activating NF-kappaB. The requirement for the phosphorylation at this site was confirmed by the specific inhibition of NF-kappaB activation in a cell-free system by the synthetic peptide corresponding to this site. The in vivo administration of an anti-CD18 antibody prevented elevation of plasma tumor necrosis factor (TNF) levels and acute lethality induced by injection of a low dose of LPS into Propionibacterium acnes-primed rabbits or by the administration of a single high dose of LPS into animals. Anti-CD18 also prevented acute lethality induced by one of the main mediators of endotoxin shock, TNF-alpha. Furthermore, an antibody to a ligand for CD18, intercellular adhesion molecule-1, also prevented TNF-induced shock as well as endotoxin shock in rabbits. These observations suggest that the interaction between leukoytes and endothelium through beta2- integrin adhesion molecules may be of primary importance in mediating LPS signals in vivo.

Idiopathic hypertrophic cranial pachymeningitis associated with hydrocephalus and myocarditis: remarkable steriod-induced remission of hypertrophic dura mater

We describe a patient with idiopathic hypertrophic cranial pachymeningitis (IHCP) associated with hydrocephalus and myocarditis in whom steroids caused remission of the hypertrophic dura and enlarged ventricles. Myocarditis induced complete atrioventricular block that responded to steroids initially but later required permanent pacemaker implantation. Serum ANA and anti-dsDNA antibody were positive. Our case suggests that IHCP and myocarditis may share a common autoimmune etiology.

A recessive lethal mutation, tb, that bends the midbrain region of the neural tube in the early embryo of the medaka

A recessive lethal mutation, tb (twisted brain), in the homozygous embryo of which the neural tube is twisted, was newly found in the medaka (Oryzias latipes). The mutation was recovered in the progeny of a male medaka which had been treated with N-ethyl-N-nitrosourea (ENU). The mutation affected morphogenic cell movements (extension and convergence) in the gastrula and neurula stages. In these stages, the embryonic body was shorter and the convergence of the neuroectodermal cells proceeded more slowly, especially in the prospective midbrain region, in the mutant embryo than in the wild-type embryo. As the neural rod formed in the mutant embryo, it curved in the midbrain region, usually protruding to the right as viewed from above. Structures lying anterior and posterior to the midbrain region were invariably present and developed fairly normally in the mutant embryo. These results show that there exists a genetically separable component in the developmental process of the formation of a straight and symmetrical neural tube.