[Signal transduction of cloned opioid receptors]

Complementary DNAs encoding delta, mu and kappa-opioid receptors have now been cloned and characterized. These receptors, which are members of the superfamily of seven transmembrane spanning receptors, share a high degree of amino acid sequence similarity among these receptors. From the similarity of the sequence, it is speculated that both the 1st and 2nd extracellular loop and the 4th membrane spanning domain are supposed to be involved in the opioid binding and subtype specificity. Because of the high similarity of the cytoplasmic regions' amino acid sequence, however, it seems that the signal transductions of delta, mu and kappa are very similar. In Xenopus oocytes expressing delta-opioid receptors and various kinds of GTP-binding protein alpha-subunits, the delta-agonist DSLET caused currents through Gi1 alpha (or Gi2 alpha)-phospholipase C mechanisms Neither G(o) alpha, Gq alpha, G11 alpha nor G14 alpha was involved in such delta-receptor-mediated responses. The higher concentration of DSLET (3-10 microM) showed a rapid desensitization upon repeated challenges. Such a rapid desensitization was purely homologous, and this was rescued by the pretreatment with protein kinase C inhibitor. Similar findings were also observed with mu and kappa-opioid receptors. These results suggest that the phosphorylation by protein kinase C is involved in the acute tolerance.

Action of FR901228, a novel antitumor bicyclic depsipeptide produced by Chromobacterium violaceum no. 968, on Ha-ras transformed NIH3T3 cells

FR901228, a novel antitumor antibiotic, reversed the transformed morphology of the Ha-ras transformants, Ras-1 cells, and inhibited their growth. The reduction of c-myc expression was observed in FR901228-treated Ras-1 cells by RNA dot-blot hybridization. This reduction of c-myc expression and morphological reversion of the transformed cells to normal were correlated with growth inhibition (G0/G1 arrest in cell cycle).

6-OHDA-induced lesion of the nigrostriatal dopaminergic neurons potentiates the inhibitory effect of 7-OHDPAT, a selective D3 agonist, on acetylcholine release during striatal microdialysis in conscious rats

Using striatal microdialysis, we attempted to clarify whether or not locally infused 7-hydroxy-N,N-di-n-propyl-2-aminotetralin (7-OHDPAT), a selective D3 agonist, modulates the basal acetylcholine (ACh) release in conscious rats sham-operated and lesioned with 6-hydroxydopamine (6-OHDA) into the medial forebrain bundle. In the sham-operated rats, 7-OHDPAT at 1 microM decreased ACh release by 19% of control. In the 6-OHDA-lesioned rats, 7-OHDPAT (0.1-10 microM) decreased ACh release in a concentration-dependent manner. The decrease of 37% of control was seen at 1 microM 2 weeks after the lesion. The 7-OHDPAT (1 microM)-induced decrease was completely antagonized by 1 microM (-)-sulpiride, a D2 and D3 antagonist, while (-)-sulpiride at 1 microM alone failed to alter ACh release. There may exist intrastriatal D3 receptors to inhibit ACh release, and supersensitization is evident in a 6-OHDA-lesioned rat Parkinson's model.

1-Phosphatidylinositol 3-kinase activity is required for insulin-stimulated glucose transport but not for RAS activation in CHO cells

Insulin stimulation drives the formation of a complex between tyrosine-phosphorylated insulin receptor substrate 1 (IRS-1) and 1-phosphatidylinositol 3-kinase (PI 3-kinase; ATP:1-phosphatidyl-1D-myo-inositol 3-phosphotransferase, EC 2.7.1.137), a heterodimer consisting of regulatory 85-kDa (p85) and catalytic 110-kDa (p110) subunits. This interaction takes place via the phosphorylated YMXM motifs of IRS-1 and the Src homology region 2 (SH2) domains of p85. In this study, the stable overexpression in a Chinese hamster ovary (CHO) cell line of a mutant p85 alpha (delta p85) protein, which lacks a binding site for p110, disrupted the complex formation between IRS-1 and the catalytic subunit of PI 3-kinase in intact cells during insulin stimulation. Activation of insulin receptor kinase and the tyrosine phosphorylation of IRS-1 remained unaffected. In this cell line, both insulin-stimulated accumulation of phosphatidylinositol 3,4,5-trisphosphate and the insulin-stimulated glucose uptake due to the translocation of GLUT1 glucose transporters were markedly impaired, whereas neither phorbol 12-myristate 13-acetate-stimulated glucose uptake nor the insulin-stimulated activation of RAS was impaired. These results suggest that PI 3-kinase is required for glucose transport in insulin signaling in CHO cells.

[Successful neoadjuvant chemotherapy in a patient with advanced gastric cancer with multiple liver metastases]

We described a case of advanced gastric cancer with multiple liver metastases, who was placed on neoadjuvant chemotherapy using CDDP and 5-FU (FP therapy) with a marked reduction in tumor load. The case was a 67-year-old male, who was admitted with a Borrmann III type advanced gastric cancer with multiple liver metastases. FP chemotherapy was carried out two times as neoadjuvant chemotherapy. As a result, both primary cancer and the metastatic tumors showed a remarkable reduction. Then, total gastrectomy with combined resections of spleen and transverse colon was done, and a reservoir was inserted into the hepatic artery. Postoperatively, intrahepatic arterial infusion of CDDP with oral administration of 5-FU was done in the outpatient clinic for about eleven months. But thirteen months later, he died from the rapid recurrence of the tumor.

Species and age-dependent differences of functional coupling between opioid delta-receptor and G-proteins and possible involvement of protein kinase C in striatal membranes

[D-Ser2,Leu5]-enkephalin-Thr6 (DSLET) and [D-Pen2,5]-enkephalin (DPDPE), both delta-agonists, stimulated the high affinity GTPase in the rat striatal membranes in a naltrindole-reversible manner. Similar stimulation was also observed in the striatal membrane preparations of 16-week-old guinea pigs, while not in those preparations of 4-week-old ones. When calphostin C, a protein kinase C inhibitor, was added to the reaction mixture, DSLET showed a marked stimulation in this activity in 4-week guinea pig striatal membranes. There was no effect of KT5720, a cyclic AMP-dependent protein kinase inhibitor, on such delta-opioid-mediated responses. These findings suggest that protein kinase C is locally involved in the functional uncoupling of delta-receptors to G-proteins in the striatum of young guinea pigs.

Supersensitivity of quinpirole-evoked GTPase activation without changes in gene expression of D2 and Gi protein in the striatum of hemi-dopaminergic lesioned rats

Quinpirole with D2 agonist activity showed a two-fold increase in the GTPase activity in the 6-hydroxydopamine-lesioned side of the striatum, compared with that in the control side. However, neither qualitative nor quantitative changes were observed in the gene expression of two alternative splicing products derived from dopamine D2 receptor gene or of Gil alpha, in the RNAase protection assay. These results suggest that D2 receptor-mediated supersensitization does not come from the D2 receptor upregulation.

[Growth of the hypoplastic aortic arch after arch repair for coarctation and interruption of the aorta]

Surgical treatment for a hypoplastic aortic arch associated with coarctation or interruption of the aorta is controversial. We evaluate the changes of diameter of proximal transverse aortic arch after surgery in 28 patients. Proximal transverse aortic arch in all patients was preoperatively 3.5 +/- 0.9 mm (2.5 to 7 mm), and 54 +/- 12% (36 to 84%) to the normal aortic valve dimension (n-AVD: 16.6 X BSA0.6). While postoperative proximal transverse aortic arch was 6.5 +/- 1.8 mm, and 76 +/- 12% to the n-AVD, and significantly grew more than the preoperative arch dimension (p = 0.0001). In 18 patients having two times cardiac catheterization postoperatively, proximal transverse aortic arch was 6.5 +/- 1.6 mm, and 75 +/- 13% to n-AVD on the 1st postoperative examination. On the 2nd examination, the arch was 9.9 +/- 1.9 mm, and 88 +/- 12% to n-AVD, and significantly grew with increasing years (p < or = 0.0003). We concluded that the proximal transverse aortic arch, which was more than 36% to n-AVD in diameter, if not dilated surgically, grew with increasing years after aortic arch repair.

Transforming growth factor-beta stimulates, and glucocorticoids and epidermal growth factor inhibit brain natriuretic peptide secretion from cultured human amnion cells

We previously reported the massive secretion of brain natriuretic peptide (BNP) from human amnion cells and suggested the possible role of BNP in the maintenance of human pregnancy. In this study, to elucidate the regulatory mechanism of BNP secretion from amnion cells, we measured the BNP level in the culture medium of amnion cells by RIA after incubation in the presence of various substances. Among the agents examined, cortisol (1 x 10(-7) to 1 x 10(-6) mol/L), dexamethasone (1 x 10(-8) to 1 x 10(-6) mol/L), and epidermal growth factor (EGF; 2 x 10(-11) to 2 x 10(-8) mol/L) inhibited BNP secretion from the cultured amnion cells in a dose-dependent manner. By contrast, transforming growth factor-beta (TGF beta; 4 x 10(-11) to 4 x 10(-9) mol/L) caused a 3- to 5-fold increase in BNP secretion. TGF beta-augmented BNP secretion was abolished by the addition of cortisol or EGF to the culture medium. Moreover, in this study, we revealed the presence of bioactive TGF beta in human amniotic fluid (approximately 4 x 10(-10) mol/L). The present finding of tight regulation of BNP secretion from amnion cells by cortisol, EGF and TGF beta, all at the concentrations physiologically present in human amniotic fluid, implies a physiological role of BNP secretion from amnion cells in the pregnant uterus.

Disturbance of autoregulation in patients with ruptured intracranial aneurysms: mechanism of cortical and motor dysfunction

Serial measurements of local cerebral blood flow were obtained with inhalation of stable xenon and computed tomography prior to and during induced hypertension with continuous infusion of dopamine (7-15 micrograms/kg/min) in 34 patients who underwent surgery for treatment of subarachnoid hemorrhage due to ruptured intracranial aneurysm. Cerebral vasospasm was detected angiographically in all but one of the patients studied. Vasospasm was not symptomatic in 19 patients, but was in the other 15 patients. Disturbance of autoregulation was observed just after surgical operation. In the latter group, local cerebral blood flow in the territory of the middle cerebral artery and the corona radiata on the craniotomy side reached their lowest values, 25.1 +/- 6.8 mL/100 g/min and 15.7 +/- 1.8 mL/100 g/min, respectively, on days 10-14, and each subsequently increased significantly, to 34.3 +/- 7.3 mL/100 g/min and 19.9 +/- 2.0 mL/100 g/min, respectively, during induced hypertension. In conclusion, cortical dysfunction and motor palsy in the patients studied here were thought to be due to significant reduction in local cerebral blood flow in the cortical territories of the middle cerebral artery and corona radiata, respectively.

A complex of GRB2-dynamin binds to tyrosine-phosphorylated insulin receptor substrate-1 after insulin treatment

Insulin drives the formation of a complex between tyrosine-phosphorylated IRS-1 and SH2-containing proteins. The SH2-containing protein Grb2 also possesses adjacent SH3 domains, which bind the Ras guanine nucleotide exchange factor Sos. In this report, we examined the involvement of another SH3 binding protein, dynamin, in insulin signal transduction. SH3 domains of Grb2 as GST fusion proteins bound dynamin from lysates of CHO cells expressing wild-type insulin receptor (IR) (CHO-IR cells) in a cell-free system (in vitro). Immunoprecipitation studies using specific antibodies against Grb2 revealed that Grb2 was co-immunoprecipitated with dynamin from unstimulated CHO-IR cells. After insulin treatment of CHO-IR cells, anti-dynamin antibodies co-immunoprecipitated the IR beta-subunit and IRS-1, as tyrosine-phosphorylated proteins and PI 3-kinase activity. However, purified rat brain dynamin did not bind directly to either the IR, IRS-1 or the p85 subunit of PI 3-kinase in vitro. Together, these results suggest that in CHO-IR cells, insulin stimulates the binding of dynamin to tyrosine-phosphorylated IRS-1 via Grb2 and that IRS-1 also associates with PI 3-kinase in response to insulin. This complex formation was reconstituted in vitro using recombinant baculovirus-expressed IRS-1, GST-Grb2 fusion proteins and dynamin peptides containing proline-rich sequences. Furthermore, dynamin GTPase activity was found to be stimulated when an IRS-1-derived phosphopeptide, containing the Grb2 binding site, was added to the dynamin-Grb2 complex in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of mixed live vaccine (Newcastle disease and infectious bronchitis) and Mycoplasma gallisepticum on the chicken respiratory tract and on Escherichia coli infection

Interaction between mixed live vaccine (Newcastle disease and infectious bronchitis), Mycoplasma gallisepticum (MG) and Escherichia coli (EC) was studied in specific-pathogen-free chickens, aged 7 days, inoculated intranasally. In the tracheas of chickens inoculated with vaccine, MG and EC, profuse multiplication of EC occurred together with severe and persisent histological lesions, and some birds died from EC infection. Similar though less dramatic effects occurred in birds that received vaccine and EC. The tracheas of chickens inoculated with the vaccine alone, or with MG and EC, or with MG alone, showed comparatively mild effects. There were no histological lesions in the tracheas of chickens inoculated with EC alone. This study suggests that the field use of mixed live vaccine in flocks infected with MG may induce EC septicaemia.

[Adrenal ganglioneuroma: report of a case]

A 52-year-old man was hospitalized for a right adrenal tumor which had been incidentally found by abdominal CT scan for examination of colon cancer. Laboratory and endocrine findings were within the normal limits except for increased urinary concentrations of noradrenaline and dopamine. Adrenal angiography revealed that the feeding artery of the tumor was the inferior suprarenal artery. Adrenal venous blood sampling studies detected no abnormalities in the concentrations of catecholamine, cortisol or aldosterone. Right adrenalectomy was performed and the tumor was histologically diagnosed as ganglioneuroma. Ganglioneuroma is a benign tumor originating from the sympathetic nerve ganglion. The adrenal origin of the tumor is relatively rare and 60 cases of adrenal ganglioneuroma including our case have been reported in Japan.

Supersensitization of intrastriatal dopamine receptors involved in opposite regulation of acetylcholine release in Parkinson's model rats

Using striatal microdialysis, we studied effects of SKF 38393, a D1 agonist, and quinpirole, a D2 agonist, on the acetylcholine (ACh) release from the striatum of 6-hydroxydopamine (6-OHDA)-lesioned rats by local infusion into the striatum. The present experiments clearly demonstrated evidence for the existence of intrastriatal D1 and D2 receptors regulating ACh release and for supersensitization of the striatal stimulatory D1 and inhibitory D2 receptor mechanisms in 6-OHDA lesioned rats.

Involvement of phosphoinositide 3-kinase in insulin- or IGF-1-induced membrane ruffling

Insulin, IGF-1 or EGF induce membrane ruffling through their respective tyrosine kinase receptors. To elucidate the molecular link between receptor activation and membrane ruffling, we microinjected phosphorylated peptides containing YMXM motifs or a mutant 85 kDa subunit of phosphoinositide (PI) 3-kinase (delta p85) which lacks a binding site for the catalytic 110 kDa subunit of PI 3-kinase into the cytoplasm of human epidermoid carcinoma KB cells. Both inhibited the association of insulin receptor substrate-1 (IRS-1) with PI 3-kinase in a cell-free system and also inhibited insulin- or IGF-1-induced, but not EGF-induced, membrane ruffling in KB cells. Microinjection of nonphosphorylated analogues, phosphorylated peptides containing the EYYE motif or wild-type 85 kDa subunit (Wp85), all of which did not inhibit the association of IRS-1 with PI 3-kinase in a cell-free system, did not inhibit membrane ruffling in KB cells. In addition, wortmannin, an inhibitor of PI 3-kinase activity, inhibited insulin- or IGF-1-induced membrane ruffling. These results suggest that the association of IRS-1 with PI 3-kinase followed by the activation of PI 3-kinase are required for insulin- or IGF-1-induced, but not for EGF-induced, membrane ruffling.

Activation of tumor-infiltrating macrophages by a synthetic lipid A analog (ONO-4007) and its implication in antitumor effects

ONO-4007 is a novel synthetic analog of lipid A subunit and has been shown to exert antitumor activities on various experimental tumors with less toxicity than lipopolysaccharide. It remains unclear, however, what biological activities of this compound are relevant to its antitumor effects. We therefore investigated the activation of macrophages by ONO-4007 in vitro and in vivo and its implication in antitumor effects, using mouse MM46 mammary tumor as an experimental model. Intravenous injection of ONO-4007 produced significant therapeutic effects on this solid tumor. ONO-4007 could stimulate glycogen-elicited peritoneal macrophages in vitro, not only to produce tumor necrosis factor (TNF), but also to exert cytocidal activities against MM46 cells in vitro. Substantial TNF production was induced in tumor tissue by i. v. injection of ONO-4007, and its successive administration to tumor-bearing mice gave tumor-infiltrating macrophages a prominent in vitro tumoricidal activity and primed them for in vitro TNF secretion. These results suggest that activation of tumor-infiltrating macrophages to a direct tumoricidal state as well as to TNF secretion in tumor tissues may be at least some of the antitumor effects of this novel lipid A analog.

Mediators of activation of fushi tarazu gene transcription by BmFTZ-F1

Transcriptional activation by many eukaryotic sequence-specific regulators appears to be mediated through transcription factors which do not directly bind to DNA. BmFTZ-F1 is a silkworm counterpart of FTZ-F1, a sequence-specific activator of the fushi tarazu gene in Drosophila melanogaster. We report here the isolation of 18- and 22-kDa polypeptides termed MBF1 and MBF2, respectively, that form a heterodimer and mediate activation of in vitro transcription from the fushi tarazu promoter by BmFTZ-F1. Neither MBF1, MBF2, nor a combination of them binds to DNA. MBF1 interacts with BmFTZ-F1 and stabilizes the BmFTZ-F1-DNA complex. MBF1 also makes direct contact with TATA-binding protein (TBP). Both MBF1 and MBF2 are necessary to form a complex between BmFTZ-F1 and TBP. We propose a model in which MBF1 and MBF2 form a bridge between BmFTZ-F1 and TBP and mediate transactivation by stabilizing the protein-DNA interactions.

The Drosophila nuclear receptors FTZ-F1 alpha and FTZ-F1 beta compete as monomers for binding to a site in the fushi tarazu gene

The striped pattern of fushi tarazu (ftz) expression found in the blastoderm of the Drosophila melanogaster embryo is generated largely through complex interactions between multiple transcription factors that bind to the zebra element of the ftz gene. A motif in the zebra element, the FTZ-F1 recognition element (F1RE), has been shown to bind a transcription factor, FTZ-F1 alpha, that is a member of the nuclear receptor family. We recently identified a second, related member of this family, FTZ-F1 beta, that also binds to this motif. To investigate the possibility that FTZ-F1 alpha and FTZ-F1 beta coregulate ftz transcription through the F1RE, we have studied the DNA binding properties of FTZ-F1 alpha and FTZ-F1 beta. We demonstrate that recombinant FTZ-F1 alpha and FTZ-F1 beta proteins produce similar in vitro DNase I footprint patterns on a 14-nucleotide region of the zebra element and bind to this site with similar affinities and sequence specificities. Using wild-type and N-terminally truncated receptors, we have determined that FTZ-F1 alpha and FTZ-F1 beta both bind as monomers to the 9-bp F1RE in the zebra element, as well as to an imperfect inverted F1RE repeat present in the Drosophila alcohol dehydrogenase gene. A polyclonal antibody raised against FTZ-F1 beta identifies a predominant F1RE-binding component in embryonic nuclear extracts. Although FTZ-F1 alpha is also present in these extracts, FTZ-F1 alpha and FTZ-F1 beta do not appear to form heterodimers with each other. Cotransfection assays in mammalian cell culture indicate that both receptors contribute to the net transcriptional activity of a reporter gene through their direct interaction with the F1RE. These data suggest that FTZ-F1 alpha and FTZ-F1 beta likely coregulate common target genes by competition for binding to a 9-bp recognition element.

Acute hepatic failure with swollen mitochondria and microvesicular fatty degeneration of hepatocytes triggered by free radical initiator

BACKGROUND

Reye syndrome and acute fatty liver of pregnancy are characterized by acute hepatic failure associated with characteristic pathologic changes of hepatocytes, i.e., microvesicular fatty degeneration with severe mitochondrial swelling. Several animal models of these conditions have been proposed, although none has demonstrated sufficiently similar laboratory and pathologic features.

EXPERIMENTAL DESIGN

A single dose of 2,2'-azobis-(2-amidinopropane) dihydrochloride, a free radical initiator, 100 mg/kg of body weight, injected intraperitoneally to BALB/c mice induced a transient decrease in hepatic energy charge, liver mitochondrial respiratory activity, and succinate dehydrogenase activity and a transient increase in blood ammonia level, suggesting hepatic failure.

RESULTS

The hepatocytes displayed microvesicular fatty degeneration with severely swollen mitochondria.

CONCLUSIONS

This is the first model of acute hepatic failure with microvesicular fatty degeneration of hepatocytes. It suggests a role of free radicals in the pathogenesis of certain types of acute hepatic failure.

Lysophosphoinositide-specific phospholipase C in rat brain synaptic plasma membranes

A membrane preparation from rat brain catalyzed the hydrolysis of [2-3H]glycerol-labeled lysophosphatidylinositol (lysoPI) to yield monoacylglycerol (MG) and inositolphosphates. This phospholipase C activity had an optimal pH of 8.2. The membrane preparation did not require the addition of Ca2+ for its maximum activity, but the activity was inhibited by addition of 0.1 mM EDTA to the assay mixture and was restored by simultaneous addition of 0.2 mM Ca2+. The activity was found to be localized in synaptic plasma membranes prepared by Ficoll and Percoll density gradients. The phospholipase C was highly specific for lysoPI; diacylglycerol formation from phosphatidylinositol, and MG formation from lysophosphatidylcholine, lysophosphatidylethanolamine, and lysophosphatidylserine were below 5% of that observed with lysoPI under the conditions used. We concluded that there is a pathway for phosphatidylinositol metabolism in brain synaptic membranes which is different from the well-characterized phosphoinositide-specific phospholipase C pathway.

Metabolic and biosynthetic alterations in cultured astrocytes exposed to hypoxia/reoxygenation

To investigate the astrocyte response to hypoxia/reoxygenation, as a model relevant to the pathogenesis of ischemic injury, cultured rat astrocytes were exposed to hypoxia. On restoration of astrocytes to normoxia, there was a dramatic increase in protein synthesis within 3 h, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis of metabolically labeled astrocyte lysates showed multiple induced bands on fluorograms. Levels of cellular ATP declined during the first 3 h of reoxygenation and the concentration of AMP increased to approximately 3.6 nmol/mg of protein within 1 h of reoxygenation. Reoxygenated astrocytes generated oxygen free radicals early after replacement into ambient air, and addition of diphenyliodonium, an NADPH oxidase inhibitor, diminished the generation of free radicals as well as the induction of several bands on fluorogram. Although addition of cycloheximide on reoxygenation resulted in inhibition of both astrocyte protein synthesis and accumulation of cellular AMP, it caused cell death within 6 h, suggesting the importance of protein synthesis in adaptation of hypoxic astrocytes to reoxygenation. Potential physiologic significance of biosynthetic products of astrocytes in hypoxia/reoxygenation was suggested by the recovery of glutamate uptake. These results indicate that the astrocyte response to hypoxia/reoxygenation includes generation of oxygen free radicals and de novo synthesis of products that influence cell viability and function in ischemia.

Early-onset type 2 (non-insulin-dependent) diabetes mellitus is associated with glucokinase locus, but not with adenosine deaminase locus, in the Japanese population

To investigate the possible contribution of glucokinase (GCK) and adenosine deaminase (ADA) loci to the genetic susceptibility to type 2 (non-insulin-dependent) diabetes mellitus, we studied the association of these loci with type 2 diabetes in the Japanese population. Fifty patients with type 2 diabetes and 50 control subjects were analyzed for microsatellite polymorphism 3' to the GCK gene and PstI polymorphism in the ADA gene by polymerase chain reaction. The frequency of the most common GCK allele (Z) was significantly lower in type 2 diabetic patients than that in control subjects and a longer Z + 2 allele was more common in type 2 diabetic patients (26% vs. 15%, P = 0.053), particularly in those with younger age of onset (33% vs. 15%, younger onset type 2 diabetes vs. control, P = 0.014). The frequency of genotypes containing at least one Z + 2 allele was significantly more common in type 2 diabetic patients (46% vs. 28%, P < 0.05), particularly in those with younger age of onset (61% vs. 28%, relative risk 4.00, P < 0.01). In contrast, there was no difference in allelic or genotypic frequencies of PstI polymorphism in the ADA gene between the two groups. Despite the association between the GCK locus and type 2 diabetes, none of the patients had known mutations (Glu265-->AM265, Glu279-->AM279, Gly299-->Arg299, Glu300-->Gln300, Leu309-->Pro309). These results suggest that the GCK locus, but not the ADA locus, contributes to the genetic susceptibility to type 2 diabetes in Japanese.(ABSTRACT TRUNCATED AT 250 WORDS)

Intermittent expression of BmFTZ-F1, a member of the nuclear hormone receptor superfamily during development of the silkworm Bombyx mori

BmFTZ-F1 is a sequence-specific DNA-binding factor in the silkworm Bombyx mori sharing similar biochemical characteristics with Drosophila FTZ-F1, a member of the nuclear hormone receptor superfamily. Using DNA sequence homology with FTZ-F1 and information on tryptic peptide sequences of BmFTZ-F1, we isolated a cDNA encoding for BmFTZ-F1. Amino acid sequences in the zinc finger DNA-binding region and the putative ligand-binding domain of BmFTZ-F1 showed strong similarity to not only FTZ-F1 but also its mammalian homologues, LRH-1, ELP, and Ad4BP, suggesting the importance of each region for the function of these proteins. Northern blot analyses of RNA isolated from the middle and posterior silk glands and fat bodies showed that a 6.1-kb BmFTZ-F1 mRNA is present in all tissues so far examined. Expression of BmFTZ-F1 mRNA is intermittent, being high during larval molting and both the larval-pupal and the pupal-adult transformations. Injection of 20-hydroxyecdysone at the third day of the 5th instar larvae induced BmFTZ-F1 mRNA in the posterior silk gland after 24 hr. When 5th instar silk glands were cultured in vitro, BmFTZ-F1 mRNA was induced by a 6-hr exposure to 20-hydroxyecdysone followed by 6 hr in hormone-free medium. These results suggest that BmFTZ-F1 is inducible by decline in the ecdysteroid titer and may play an important role in the development of the silkworm as a transcription factor.

Non-effective dose of exogenously applied L-dopa itself stereoselectively potentiates postsynaptic D2 receptor-mediated locomotor activities of conscious rats

We attempted to clarify whether or not under inhibition of central dopa decarboxylase non-effective i.p. doses of L-dopa potentiate D2 receptor-mediated locomotor activities without conversion to dopamine in normal and i.v.t. 6-hydroxydopamine-treated rats. In normal rats, only the highest dose of quinpirole, a selective D2 agonist, at ranges used (0.01-1 mg/kg, s.c.) slightly increased the total counts of locomotor activities for 140 min after injection. A simultaneously injected non-effective dose of L-DOPA (30 mg/kg) potentiated locomotor activities by quinpirole (0.1 and 1 mg/kg). L-dopa potentiated quinpirole (1 mg/kg)-induced locomotor activities 90 to 140 min after the injection with marked increase in basal release of L-DOPA without increase in dopamine release simultaneously monitored during striatal microdialysis, compared to quinpirole alone. D-dopa (30 mg/kg) produced no potentiation. In 6-hydroxydopamine-treated rats, a non-effective dose of L-dopa (10 mg/kg) also potentiated quinpirole (0.3 mg/kg)-induced locomotor activities. L-dopa acting on a recognition site for itself stereoselectively potentiates postsynaptic D2 receptor-mediated locomotor activities of rats.