A genome-wide association study identifies two novel susceptibility loci and trans population polygenicity associated with bipolar disorder.

Genome-wide association studies (GWASs) have identified several susceptibility loci for bipolar disorder (BD) and shown that the genetic architecture of BD can be explained by polygenicity, with numerous variants contributing to BD. In the present GWAS (Phase I/II), which included 2964 BD and 61 887 control subjects from the Japanese population, we detected a novel susceptibility locus at 11q12.2 (rs28456, P=6.4 × 10-9), a region known to contain regulatory genes for plasma lipid levels (FADS1/2/3). A subsequent meta-analysis of Phase I/II and the Psychiatric GWAS Consortium for BD (PGC-BD) identified another novel BD gene, NFIX (Pbest=5.8 × 10-10), and supported three regions previously implicated in BD susceptibility: MAD1L1 (Pbest=1.9 × 10-9), TRANK1 (Pbest=2.1 × 10-9) and ODZ4 (Pbest=3.3 × 10-9). Polygenicity of BD within Japanese and trans-European-Japanese populations was assessed with risk profile score analysis. We detected higher scores in BD cases both within (Phase I/II) and across populations (Phase I/II and PGC-BD). These were defined by (1) Phase II as discovery and Phase I as target, or vice versa (for 'within Japanese comparisons', Pbest~10-29, R2~2%), and (2) European PGC-BD as discovery and Japanese BD (Phase I/II) as target (for 'trans-European-Japanese comparison,' Pbest~10-13, R2~0.27%). This 'trans population' effect was supported by estimation of the genetic correlation using the effect size based on each population (liability estimates~0.7). These results indicate that (1) two novel and three previously implicated loci are significantly associated with BD and that (2) BD 'risk' effect are shared between Japanese and European populations.

Risk factors for decreased teicoplanin trough concentrations during initial dosing in critically ill patients.

Aim of the study: Here, we investigated the risk factors for decreased teicoplanin plasma trough concentrations relative to the initial dosing in critically ill patients. Patients and methods: Data obtained from 80 eligible critically ill patients who received intravenous teicoplanin were retrospectively analyzed. Risk factors for decreases in teicoplanin trough concentrations 72 h after administration of teicoplanin of more than 30% relative to predicted concentrations based on initial dosing setting were identified by logistic regression analysis. Results: Although prediction trough concentration and total dose of two days no significant differences were seen between the variation group and the non-variation group, actual trough concentration was significantly different between two groups (19.9±5.6 µg/ml vs 10.3±2.2 µg/ml, p < 0.001). In multivariate analysis, serum albumin ≤ 2.2 mg/dl (odds ratio [OR] = 3.003, 95% CI 1.072-8.408; p = 0.036) and SOFA score ≥ 9 (OR = 3.498, 95% CI 1.171-10.450; p = 0.025) were significant risk factors for decreased teicoplanin plasma trough concentrations. Conclusion: In critically ill patients, high SOFA score and low serum albumin were risk factors for decreased teicoplanin plasma trough concentration during initial dosing.

High-resolution copy number variation analysis of schizophrenia in Japan.

Recent schizophrenia (SCZ) studies have reported an increased burden of de novo copy number variants (CNVs) and identified specific high-risk CNVs, although with variable phenotype expressivity. However, the pathogenesis of SCZ has not been fully elucidated. Using array comparative genomic hybridization, we performed a high-resolution genome-wide CNV analysis on a mainly (92%) Japanese population (1699 SCZ cases and 824 controls) and identified 7066 rare CNVs, 70.0% of which were small (<100 kb). Clinically significant CNVs were significantly more frequent in cases than in controls (odds ratio=3.04, P=9.3 × 10-9, 9.0% of cases). We confirmed a significant association of X-chromosome aneuploidies with SCZ and identified 11 de novo CNVs (e.g., MBD5 deletion) in cases. In patients with clinically significant CNVs, 41.7% had a history of congenital/developmental phenotypes, and the rate of treatment resistance was significantly higher (odds ratio=2.79, P=0.0036). We found more severe clinical manifestations in patients with two clinically significant CNVs. Gene set analysis replicated previous findings (e.g., synapse, calcium signaling) and identified novel biological pathways including oxidative stress response, genomic integrity, kinase and small GTPase signaling. Furthermore, involvement of multiple SCZ candidate genes and biological pathways in the pathogenesis of SCZ was suggested in established SCZ-associated CNV loci. Our study shows the high genetic heterogeneity of SCZ and its clinical features and raises the possibility that genomic instability is involved in its pathogenesis, which may be related to the increased burden of de novo CNVs and variable expressivity of CNVs.

A simplified chart for determining the initial loading dose of teicoplanin in critically ill patients.

AIM OF THE STUDY: A simplified chart to determine the initial loading dose of teicoplanin (TEIC chart) for achieving the target trough concentration was developed. The aim of the present study was to evaluate the usefulness of this chart in critically ill patients. PATIENTS AND METHODS: The initial loading dose and maintenance dose to achieve a target trough concentration ≥10 µg/mL on day 4 was determined using the teicoplanin TDM software and presented in a TEIC chart. The dosage of teicoplanin, including the loading dose for the first 2 days and the maintenance dose thereafter, was selected from the chart (chart method, N = 41) or calculated using TDM software (software method, N = 39). RESULTS: The performance rate of initial loading of teicoplanin increased from 83.0% to 100% after the TEIC chart was introduced (P = 0.016). The TEIC chart significantly reduced the time required for determining the initial loading dose compared with the use of software (1.9±0.6 min vs. 29.7±13.8 min, P < 0.001). No significant differences were observed in the rates of achieving a target level ≥10 µg/mL (P = 0.766). CONCLUSION: The TEIC chart enables a simple, rapid, and reliable determination of teicoplanin dosage.

Production of functional coagulation factor VIII from iPSCs using a lentiviral vector.

The use of induced pluripotent stem cells (iPSCs) as an autologous cell source has shed new light on cell replacement therapy with respect to the treatment of numerous hereditary disorders. We focused on the use of iPSCs for cell-based therapy of haemophilia. We generated iPSCs from mesenchymal stem cells that had been isolated from C57BL/6 mice. The mouse iPSCs were generated through the induction of four transcription factor genes Oct3/4, Klf-4, Sox-2 and c-Myc. The derived iPSCs released functional coagulation factor VIII (FVIII) following transduction with a simian immunodeficiency virus vector. The subcutaneous transplantation of iPSCs expressing FVIII into nude mice resulted in teratoma formation, and significantly increased plasma levels of FVIII. The plasma concentration of FVIII was at levels appropriate for human therapy at 2-4 weeks post transplantation. Our data suggest that iPSCs could be an attractive and prospective autologous cell source for the production of coagulation factor, and that engineered iPSCs expressing coagulation factor might provide a cell-based therapeutic strategy appropriate for haemophilia.

Immune response against serial infusion of factor VIII antigen through an implantable venous-access device system in haemophilia A mice.

Haemophilia A is a life long bleeding disorder caused by an inherited deficiency of factor VIII (FVIII). About 30% of haemophilia A patients develop neutralizing antibodies as a consequence of treatment with FVIII concentrates. Immune tolerance protocols for the eradication of inhibitors require daily delivery of intravenous FVIII. We evaluated the immune responses to serial intravenous administration of FVIII in preimmunized haemophilia A mice. We introduced an implantable venous-access device (iVAD) system into haemophilia A mice to facilitate sequential infusion of FVIII. After preimmunization with FVIII, the haemophilia A mice were subjected to serial intravenous administration of FVIII through the iVAD system. In all mice with serial infusion of FVIII, high titers of anti-FVIII inhibitory antibodies developed at 10 exposure days (EDs). However, the anti-FVIII IgG titers were decreased after 150 EDs of sequential low-dose infusion of FVIII [0.05 U g(-1) body weight (BW) five times per week]. Proliferative response to ex vivo FVIII stimulation was significantly suppressed in splenic CD4(+) T cells from mice with serial low-dose FVIII infusion compared with those from mice with high-dose FVIII infusion (0.5 U g(-1) BW five times per week) or preimmunized mice. Moreover, splenic CD4(+) T cells from mice with serial low-dose infusion of FVIII failed to produce interleukin-2 and interferon-γ. These data suggest that serial infusion of FVIII could induce T-cell anergy in haemophilia A mice with inhibitor antibodies.

Outcome measurement of extensive implementation of antimicrobial stewardship in patients receiving intravenous antibiotics in a Japanese university hospital.

BACKGROUND: Antimicrobial stewardship has not always prevailed in a wide variety of medical institutions in Japan. METHODS: The infection control team was involved in the review of individual use of antibiotics in all inpatients (6348 and 6507 patients/year during the first and second annual interventions, respectively) receiving intravenous antibiotics, according to the published guidelines, consultation with physicians before prescription of antimicrobial agents and organisation of education programme on infection control for all medical staff. The outcomes of extensive implementation of antimicrobial stewardship were evaluated from the standpoint of antimicrobial use density, treatment duration, duration of hospital stay, occurrence of antimicrobial-resistant bacteria and medical expenses. RESULTS: Prolonged use of antibiotics over 2 weeks was significantly reduced after active implementation of antimicrobial stewardship (2.9% vs. 5.2%, p < 0.001). Significant reduction in the antimicrobial consumption was observed in the second-generation cephalosporins (p = 0.03), carbapenems (p = 0.003), aminoglycosides (p < 0.001), leading to a reduction in the cost of antibiotics by 11.7%. The appearance of methicillin-resistant Staphylococcus aureus and the proportion of Serratia marcescens to Gram-negative bacteria decreased significantly from 47.6% to 39.5% (p = 0.026) and from 3.7% to 2.0% (p = 0.026), respectively. Moreover, the mean hospital stay was shortened by 2.9 days after active implementation of antimicrobial stewardship. CONCLUSION: Extensive implementation of antimicrobial stewardship led to a decrease in the inappropriate use of antibiotics, saving in medical expenses, reduction in the development of antimicrobial resistance and shortening of hospital stay.

Evaluation of the efficacy and safety of the combination of gemcitabine and nedaplatin for elderly patients with advanced non-small-cell lung cancer.

OBJECTIVE: The aim of the present study was to retrospectively assess the safety and efficacy of the combination of gemcitabine and nedaplatin in elderly patients with advanced non-small-cell lung cancer (NSCLC). METHODS: Patients ≥75 years with previously untreated NSCLC who underwent chemotherapy consisting of gemcitabine (800 mg/m(2) on days 1 and 8) and nedaplatin (80 mg/m(2) on day 1) every 3 weeks were retrospectively analyzed. RESULTS: Of the 35 patients, 28 were men and 7 were women, with a mean age of 78 years (range 75-87); 10 patients had stage IIIB disease and 25 patients had stage IV disease. The overall response rate was 45.7% (95% confidence interval 28.8-63.4). The median survival time was 14 months (range 3-44). Grade 3-4 toxicities included neutropenia in 74.3%, thrombocytopenia in 48.6%, anemia in 34.3%, hepatic dysfunction in 11.4%, and infection in 2.9%. There were no treatment-related deaths. There were no differences in response rate and survival between patients aged 75-79 years and patients ≥80 years, although grade 3-4 thrombocytopenia and anemia were significantly more frequent in patients ≥80 years. CONCLUSION: Our results suggest that the combination of gemcitabine and nedaplatin is effective and well tolerated for selected elderly patients with advanced NSCLC.

Skeletal malformations caused by overexpression of Cbfa1 or its dominant negative form in chondrocytes.

During skeletogenesis, cartilage develops to either permanent cartilage that persists through life or transient cartilage that is eventually replaced by bone. However, the mechanism by which cartilage phenotype is specified remains unclarified. Core binding factor alpha1 (Cbfa1) is an essential transcription factor for osteoblast differentiation and bone formation and has the ability to stimulate chondrocyte maturation in vitro. To understand the roles of Cbfa1 in chondrocytes during skeletal development, we generated transgenic mice that overexpress Cbfa1 or a dominant negative (DN)-Cbfa1 in chondrocytes under the control of a type II collagen promoter/enhancer. Both types of transgenic mice displayed dwarfism and skeletal malformations, which, however, resulted from opposite cellular phenotypes. Cbfa1 overexpression caused acceleration of endochondral ossification due to precocious chondrocyte maturation, whereas overexpression of DN-Cbfa1 suppressed maturation and delayed endochondral ossification. In addition, Cbfa1 transgenic mice failed to form most of their joints and permanent cartilage entered the endochondral pathway, whereas most chondrocytes in DN-Cbfa1 transgenic mice retained a marker for permanent cartilage. These data show that temporally and spatially regulated expression of Cbfa1 in chondrocytes is required for skeletogenesis, including formation of joints, permanent cartilages, and endochondral bones.

The impact of external fixation on mortality in patients with an unstable pelvic ring fracture: a propensity-matched cohort study.

AIM: There is not adequate evidence to establish whether external fixation (EF) of pelvic fractures leads to a reduced mortality. We used the Japan Trauma Data Bank database to identify isolated unstable pelvic ring fractures to exclude the possibility of blood loss from other injuries, and analyzed the effectiveness of EF on mortality in this group of patients. PATIENTS AND METHODS: This was a registry-based comparison of 1163 patients who had been treated for an isolated unstable pelvic ring fracture with (386 patients) or without (777 patients) EF. An isolated pelvic ring fracture was defined by an Abbreviated Injury Score (AIS) for other injuries of < 3. An unstable pelvic ring fracture was defined as having an AIS ≥ 4. The primary outcome of this study was mortality. A subgroup analysis was carried out for patients who required blood transfusion within 24 hours of arrival in the Emergency Department and those who had massive blood loss (AIS code: 852610.5). Propensity-score matching was used to identify a cohort like the EF and non-EF groups. RESULTS: With the use of propensity-score matching using the completed data, 346 patients were matched. When the propensity-score matching was adjusted, EF was associated with a significantly lower risk of death (p = 0.047). In the subgroup analysis of patients who needed blood transfusion within 24 hours and those who had massive blood loss, EF was associated with a significantly lower risk of death in patients who needed blood transfusion within 24 hours (p = 0.014) and in those with massive blood loss (p = 0.016). CONCLUSION: The use of EF to treat unstable pelvic ring fractures was associated with a significantly lower risk of death, especially in patients with severe fractures. Cite this article: Bone Joint J 2018;100-B:233-41.

Phospholipase C-mediated hydrolysis of phosphatidylcholine is activated by cis-diamminedichloroplatinum(II).

We have investigated the effect of cis-diamminedichloroplatinum(II) (CDDP) on signal transduction pathways. CDDP treatment did not cause any change in the binding of [3H]-phorbol dibutyrate to PC-9 (human lung adenocarcinoma cell line) cells, a measure of protein kinase C activation. However, 2-h CDDP treatment (20 micrograms/ml) caused approximately 200% increase in 1,2-sn-diacylglycerol (DAG) production and approximately 50% decrease in inositol 1,4,5-triphosphate production. To explore the different source of DAG, we analyzed phospholipids labeled with [14C]choline by TLC and revealed that [14C]choline-labeled phosphatidylcholine (PC) was decreased to 50% by CDDP treatment. This suggested that PC turnover was increased by CDDP-treatment. PC-specific phospholipase C (PC-PLC) activity was increased to 2.5-fold (2.58 +/- 0.28 nmol/mg protein per min) by 2 h CDDP (20 micrograms/ml) treatment compared with control (1.05 +/- 0.24 nmol/mg protein per min). Treatment of CDDP also stimulated PC-PLC in the crude membrane extract from PC-9 cells. CDDP had no effect on the activities of phospholipase A2 and D. Trans-DDP, which has far less cytotoxicity than its stereoisomer, CDDP, did not cause any change in PC-PLC activity. A significant inhibition of DNA synthesis (less than 80%) occurred 4 h after 2 h CDDP (20 micrograms/ml) treatment. These results demonstrated that CDDP-induced PC-PLC activation was an early event in CDDP-induced cytotoxicity and suggested that the effects of CDDP on signal transduction pathways had an important role in CDDP-induced cytotoxicity.

Aspirin resistance detected with aggregometry cannot be explained by cyclooxygenase activity: involvement of other signaling pathway(s) in cardiovascular events of aspirin-treated patients.

OBJECTIVES: Although the concept of aspirin resistance is extensively reported in medical literature, its precise mechanisms and clinical outcomes are largely unknown. In this study, we examined individual thromboxane biosynthesis and platelet aggregation in aspirin-treated patients, and whether the results of a platelet aggregation test influenced clinical outcomes. RESULTS: Subjects taking 81 mg of aspirin (n = 50) and controls (n = 38) were evaluated for platelet aggregation and platelet cyclooxygenase-1 (COX-1) activity by measuring collagen-induced thromboxane B2 production. For aggregometry, both light transmission (LT) and laser-light scattering methods were employed to quantitatively evaluate aggregate sizes and numbers. Aspirin treatment resulted in the inhibition of collagen-induced platelet aggregation, particularly the transition from small to large platelet aggregates. Although platelet COX-1 activity seemed to be uniformly inhibited in all patients, platelet aggregation studies showed great inter-individual differences; variation in platelet COX-1 activity only accounted for 6-20% of the individual aggregations. Factor analysis revealed the existence of a common factor (other than platelet COX-1) that explained 48.4% of the variations in platelet aggregation induced by collagen, adenosine diphosphate (ADP), and collagen-related peptide. We then prospectively enrolled 136 aspirin-treated patients in our study, and we found that being in the upper quartile level of LT, or with large aggregate formation induced by collagen, was an independent risk factor for developing cardiovascular events within 12 months [hazard ratio (HR) = 7.98, P = 0.008 for LT; HR = 7.76, P = 0.007 for large aggregates]. On the other hand, the existence of diabetes mellitus was an independent risk factor for overall outcomes (HR 1.30-11.9, P = 0.015-0.033). CONCLUSIONS: Aspirin resistance expressed as unsuppressed platelet COX-1 activity is a rare condition in an out-patient population. Other factor(s) affecting collagen-induced platelet aggregation may influence early outcomes in aspirin-treated patients.

A classification of the fibrin network structures formed from the hereditary dysfibrinogens.

OBJECTIVE: The main objective was to study the relationships of the molecular defects in 38 dysfibrinogens with their fibrin networks. METHODS AND RESULTS: Scanning electron microscopic analyses revealed that all the fibrins formed under the same conditions had networks composed of either normal thickness fibers or thin fibers, accompanied by a variety of alterations in the network structure and characteristics. We classified these fibrin networks into five classes, designated normal, less-ordered, porous A, porous B and lace-like networks. The dysfibrinogens with defects in fibrinopeptide A release or the E:D binding sites formed normal or less-ordered networks, while those with defects in the D:D association formed porous A networks composed of many tapered terminating fibers, despite having fibers of normal width, and containing many pores or spaces. The porous B and lace-like networks were composed of highly branched thin fibers because of defects in the lateral association among protofibrils, and the major difference between them was the porosity of the porous B networks. All the porous B networks were easily damaged by mechanical stress, whereas the lace-like networks retained high resistance to such stress, indicating that the network strength was not dependent on the fiber width, but on the porosity that led to fragility of the network. CONCLUSION: Impairment of the D:D association is the major disturbing factor that leads to the formation of porous fibrin networks. The porosity may be introduced by severe impairment of the D:D association, as well as the lateral association, as has often been observed by extra glycosylation or defects in Ca2+ binding.

Enhancing effect on N-nitrosodimethylamine-induced tumorigenesis by unilateral hydronephrosis.

The effect of unilateral hydronephrosis (U-HN) on chemical tumorigenesis by two im injections of N-nitrosodimethylamine (DMN; CAS: 62-75-9) with the use of inbred female W rats was studied. Of the rats in the U-HN group, 70.0% developed kidney tumors, 25.0% developed mammary tumors, 20.0% developed hepatomas, and 20.0% developed other tumors. Almost all kidney tumors in the U-HN group (96.0%) were induced in the compensatory (contralateral) kidney. In contrast, of the rats in the unilateral nephrectomy (U-NR) group, 29.4% developed kidney tumors, 11.8% developed mammary tumors, 23.5% developed hepatomas, and 11.8% developed other tumors. Rats in the sham-operated group developed 1 small kidney tumor (7.7% of the rats) but no tumors in other organs. Thus, under these conditions, U-NR and especially U-HN strongly increased tumor induction in DMN tumorigenesis not only in the compensatory kidney but also in extrarenal organs.

Modulation of N-nitrosodimethylamine kidney tumorigenesis by unilateral hydronephrosis and multiple putrescine administrations.

The effects of unilateral hydronephrosis by ligation of the right ureter and/or multiple injections of putrescine on kidney tumorigenesis by a single intrarenal injection of N-nitrosodimethylamine (DMN) were studied. Inbred female W rats in the unilateral hydronephrotic groups given or not given putrescine developed kidney tumors and/or neoplastic or preneoplastic lesions of the liver at an incidence of 55.6%. Almost all kidney tumors developed in the contralateral kidneys, which showed hypertrophy due to unilateral hydronephrosis. Rats having unilateral hydronephrosis and subjected to long-term putrescine administration after DMN injection frequently contracted large mesenchymal cell tumors (83%), whereas the group not given putrescine developed no mesenchymal cell tumors. Histologically, epithelial cell tumors showed a marked decrease in both gamma-glutamyltransferase activity and trypan blue uptake, but mesenchymal cell tumors did not.

Absence of uniform progressive growth of long-term transplants of rat liver neoplastic nodules.

Fragments of normal rat liver and neoplastic nodules induced by feeding 0.02% N-2-fluorenylacetamide for 20 weeks were transplanted into the inguinal mammary fat pads of syngeneic rats. All animals were Charles River inbred male albino rats of the CDF strain derived from the F344 strain. Normal liver transplants and neoplastic nudule transplants were detected histologically in the transplant site up to 24 and 66 weeks of survival, respectively. Of 30 nodule transplants followed up to 121 weeks, only 1 neoplastic nodule developed progressive neoplastic growth. The tumor that arose in the transplant site from this nodule was a well-differentiated adenocarcinoma with mucin production. Thus rat liver neoplastic nodules lack the high frequency of progressive growth previously demonstrated for carcinomas.

Early stages of N-2-fluorenylacetamide-induced hepatocarcinogenesis in male and female rats and effect of gonadectomy on liver neoplastic conversion and neoplastic development.

The early stages of N-2-fluorenylacetamide [(2-FAA) CAS: 59-96-3]-induced liver carcinogenesis in inbred F344 male and female rats and the effect of gonadectomy on liver carcinogen biotransformation capability and hepatocarcinogenesis were studied. Feeding of 2-FAA induced more altered hepatocellular foci characterized by exclusion of cellular iron and gamma-glutamyl-transferase activity in male rats than in female rats. At 6-22 weeks after cessation of carcinogen exposure, only males developed liver neoplastic nodules. Liver cytochrome P450, aryl hydrocarbon hydroxylase, and uridine-5'-diphosphateglucuronosyltransferase activity toward p-nitrophenol, but not phenolphthalein, were greater in males than in females. Gonadectomy of males reduced the activities that were greater than in females, whereas none was significantly altered by gonadectomy of females. Gonadectomy of male rats prior to 2-FAA feeding suppressed the induction of both altered foci and neoplastic nodules, whereas in female rats gonadectomy prior to 2-FAA feeding enhanced the induction of foci. Gonadectomy of males after administration of 2-FAA slightly enhanced the persistence of foci at 6 and 12 weeks after removal of carcinogen, but it did not affect their persistence by 22 weeks post carcinogen or the incidence of neoplastic nodules. However, only the males that were gonadectomized after receiving 2-FAA developed hepatocellular carcinomas at 22 weeks. Gonadectomy of females after receiving 2-FAA did not affect the persistence of foci, and no liver neoplasms developed. Thus gonadectomy of male rats, which reduced liver carcinogen metabolism, when done before carcinogen feeding had the greatest effect on hepatocarcinogenesis.

Effect of intestinal microflora and dietary fat on 3,2'-dimethyl-4-aminobiphenyl-induced colon carcinogenesis in F344 rats.

The effect of dietary fat and intestinal microflora on colon and small intestinal carcinogenesis was studied in weanling male F344 germfree and conventional rats fed semipurified diets containing low and high fat. At 7 weeks of age, all animals, except vehicle-treated groups, received weekly s.c. injections of 50 mg 3,2'-dimethyl-4-aminobiphenyl (DMAB) per kg body weight for 20 weeks. The DMAB- and vehicle-treated germfree and conventional rats fed high- and low-fat diets were autopsied 20 weeks after the last injection of DMAB. The incidence of colon, small intestinal, ear duct, and skin tumors was lower in germfree rats than in the conventional animals. The incidence and multiplicity of DMAB-induced colon tumors were higher in conventional rats fed the high-fat diet than in the conventional animals fed the low-fat diet; however, the tumor incidence did not differ significantly between the high- and low-fat-fed germfree animals. Dietary fat had no effect on the incidence of small intestinal tumors in both germfree and conventional rats.

Serotonin as a major serum factor inducing the phospholipase C-mediated hydrolysis of phosphoinositides in normal rat kidney cells.

Calf serum induced the phospholipase C-mediated hydrolysis of phosphoinositides in normal rat kidney (NRK) cells transformed by a temperature-sensitive Kirsten murine sarcoma virus (tsK-NRK cells). Various growth factors known to induce the phospholipase C reactions in other cell types, such as platelet-derived growth factor, fibroblast growth factor, epidermal growth factor, thrombin, vasopressin, bombesin, cholecystokinin, and prostaglandin F2 alpha, did not induce phospholipase C reactions in the transformed NRK cells. Furthermore, noradrenaline, histamine, dopamine, angiotensin II, carbachol, and tumor growth factor-beta did not induce phospholipase C reactions. However, serotonin did induce phospholipase C reactions. The amount of serotonin contained in the calf serum was sufficient to support 50% of the activity promoted by the serum itself, and calf serum-induced phospholipase C reactions were inhibited to 10-20% of the original level by ketanserin and methysergide, known to be antagonists for the serotonin receptors. Dialysis almost completely removed serotonin from calf serum and reduced the serum-induced phospholipase C reactions. Moreover, the phospholipase C reactions induced by calf serum and serotonin were inhibited by pretreatment of the cells with pertussis toxin or 12-O-tetradecanoylphorbol-13-acetate. These results indicate that serotonin is one of the major serum factors inducing phospholipase C-mediated hydrolysis of phosphoinositides in transformed NRK cells. Serotonin induced phospholipase C reactions not only in tsK-NRK cells but also in nontransformed NRK cells. However, serotonin did not induce these reactions in Swiss 3T3 cells or NIH 3T3 cells.