Integrin α3 is overexpressed in glioma stem-like cells and promotes invasion.

BACKGROUND: Glioma stem-like cell (GSC) properties are responsible for gliomagenesis and recurrence. GSCs are invasive but its mechanism remains to be elucidated. Here, we attempted to identify the molecules that promote invasion in GSCs. METHODS: Neurospheres and CD133⁺ cells were collected from glioblastoma (GBM) specimens and glioma cell lines by sphere-formation method and magnetic affinity cell sorting, respectively. Differential expression of gene candidates, its role in invasion and its signaling pathway were evaluated in glioma cell lines. RESULTS: Neurospheres from surgical specimens attached to fibronectin and laminin, the receptors of which belong to the integrin family. Integrin α3 was overexpressed in CD133⁺ cells compared with CD133⁻ cells in all the glioma cell lines (4 out of 4). Immunohistochemistry demonstrated the localisation of integrin α3 in GBM cells, including invading cells, and in the tumour cells around the vessels, which is believed to be a stem cell niche. The expression of integrin α3 was correlated with migration and invasion. The invasion activity of glioma cells was linked to the phosphorylation of extracellular signal-regulated kinase (ERK) 1/2. CONCLUSION: Our results suggest that integrin α3 contributes to the invasive nature of GSCs via ERK1/2, which renders integrin α3 a prime candidate for anti-invasion therapy for GBM.

Selective activation of the proto-oncogene c-jun promoter by the transforming protein v-Rel.

The transcription factor v-Rel is a transforming protein of the reticuloendotheliosis virus. We found that v-Rel activates the promoter of the proto-oncogene c-jun. Two elements in the c-jun promoter were required for the activation by v-Rel. One was a kB-site (v-Rel binding site), and the other was a c-jun promoter region between -52 and +148 (c-jun promoter (-52/+148)). Two promoters with the kB-site(s), those of human immunodeficiency virus (HIV) and SV40, were not activated by v-Rel, but their kB-sites were activated when introduced upstream of the c-jun promoter (-52/+148). Thus, the c-jun promoter (-52/+148) had information for the selective activation of the c-jun promoter by v-Rel. v-Rel bound to the c-jun kB-site with the higher affinity than c-Rel, thereby activating the c-jun promoter more efficiently than c-Rel. Moreover, the activity of v-Rel mutants upon the c-jun promoter correlates with their transforming activity. Thus, the c-jun promoter activation by v-Rel may play a role in the transformation caused by v-Rel.

Selective inducible nitric oxide synthase inhibition attenuates organ dysfunction and elevated endothelin levels in LPS-induced DIC model rats.

We examined the role of nitric oxide (NO) produced by an inducible isoform of NO synthase (iNOS) using N[6]-(iminoethyl)-lysine (L-NIL), a selective iNOS inhibitor, in the rat model of lipopolysaccharide (LPS)-induced disseminated intravascular coagulation (DIC) and investigated changes in organ function, plasma levels of NOX (metabolites of NO) and endothelin. We induced experimental DIC by the sustained infusion of 30 mg kg(-1) LPS for 4 h via the tail vein. We then investigated the effect of L-NIL (6 mg kg(-1), from - 0.5 to 4 h) on LPS-induced DIC. Blood was withdrawn at 4 and 8 h, and all four groups (LPS with or without L-NIL at 4 and 8 h) consisted of eight rats. Three of the animals in the 8-h LPS group died, and we examined blood samples from five rats in this group. None of the other rats died. The LPS-induced elevation of creatinine, alanine aminotransferase, glomerular fibrin deposition and plasminogen activator inhibitor was significantly suppressed by L-NIL coadministration, although L-NIL did not affect the platelet count, fibrinogen concentration or the level of thrombin-antithrombin complex. Moreover, plasma levels of the D-dimer that reflect the lysis of cross-linked fibrin were significantly increased by L-NIL coadministration in the LPS-induced DIC model. Plasma levels of NOX and endothelin were obviously increased by LPS infusion. However, both levels were significantly suppressed in the LPS + L-NIL group, when compared with the LPS group. Although mean arterial pressure (MAP) was significantly decreased between 2 and 8 h compared with the control in the LPS group, this depression was significantly attenuated in the LPS + L-NIL group. Our results suggest that NO induced by iNOS contributes to hypotension (depressed MAP), the progression of hepatic and renal dysfunction, microthrombus deposition and elevated endothelin levels in the rat model of LPS-induced DIC.

The polymorphism in the caudal-related homeodomain protein Cdx-2 binding element in the human vitamin D receptor gene.

The major physiological activity of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] is the regulation of calcium absorption in the small intestine, and the level of vitamin D receptor (VDR) is an important factor in this regulation. In a previous study, we indicated-that the caudal-related homeodomain Cdx-2 played an important role in the intestine-specific transcription of the human VDR gene. In this study, the polymorphism was identified in the core sequence 5'-ATAAAAACTTAT-3' in the Cdx-2 binding site in the VDR gene promoter. In 261 Japanese women with genotyped VDR polymorphisms, 48 were genotype Cdx-A (adenine at -3731 nucleotides [nt] relative to the transcription start site of human VDR gene 5-ATAAAAACTTAT), 82 were genotype Cdx-G (guanine at -3731 nt, 5'-GTAAAAACTTAT-3'), and 131 were genotype Cdx-A/G (heterozygote). In postmenopausal Japanese women, the bone mineral density (BMD) in the lumbar spine (L2-L4) with the Cdx-G homozygote was 12% lower than that with the Cdx-A homozygote (p < 0.05). In electrophoretic gel mobility shift assay (EMSA), the oligonucleotide with Cdx-G allele markedly decreased the binding to Cdx-2 compared with that in the Cdx-A allele. The transcriptional activity of the VDR promoter with Cdx-G allele was decreased to 70% of the Cdx-A allele. In addition, in the herpes simplex virus thymidine kinase promoter, the Cdx-2 binding element with the G allele showed significantly lower transcriptional activity than that of the A allele. Thus, the polymorphism in the Cdx-2 binding site of the VDR gene (Cdx-polymorphism) would affect the expression of VDR in the small intestine. In addition, this polymorphism may modulate BMD in postmenopausal Japanese women.

Molecular cloning and hormonal regulation of PiT-1, a sodium-dependent phosphate cotransporter from rat parathyroid glands.

The extracellular concentration of inorganic phosphate (Pi) is an important determinant of parathyroid cell function. The effects of Pi may be mediated through specific molecules in the parathyroid cell membrane, one candidate molecule for which would be a Na+-dependent Pi cotransporter. A complementary DNA encoding a Na+-Pi cotransporter, termed rat PiT-1, has now been isolated from rat parathyroid. The 2890-bp complementary DNA encodes a protein of 681 amino acids that shows sequence identities of 97% and 93% with the type III Na+-Pi cotransporters mouse PiT-1 and human PiT-1, respectively. Expression of rat PiT-1 in Xenopus oocytes revealed that it possesses Na+-dependent Pi cotransport activity. PiT-1 messenger RNA (mRNA) is widely distributed in rat tissues and is most abundant in brain, bone, and small intestine. The amount of PiT-1 mRNA in the parathyroid of vitamin D-deficient rats was reduced compared with that in normal animals and increased markedly after administration of 1,25-dihydroxyvitamin D3. Furthermore, the abundance of PiT-1 mRNA in the parathyroid was much greater in rats fed a low-Pi diet than in those fed a high-Pi diet. Thus, rat PiT-1 may contribute to the effects of Pi and vitamin D on parathyroid function.

Close correlation between estrogen treatment and renal phosphate reabsorption capacity.

To determine the influence of estrogen on the activity of renal proximal tubular reabsorption of inorganic phosphate (Pi) in women, we examined the changes of the renal threshold phosphate concentration (also denoted as TmP/GFR), as well as the changes in the concentrations of mineral components in the circulation in two groups of women--one receiving hormone replacement therapy (HRT) and one receiving gonadotropin-releasing hormone agonists (GnRH-a) therapy. We also examined the changes in the concentrations of serum PTH in the GnRH-a group. The patients in the HRT group were continuously treated with 0.625 mg conjugated equine estrogens plus 2.5 mg medroxyprogesterone acetate per day. The patients in the GnRH-a group were treated with a monthly injection of 3.75 mg leuprolide acetate depot for 6 months. The values of TmP/GFR decreased in all of the patients who received HRT. The mean percentage change in TmP/GFR was -14.5% (range, -24.3% to -9.6%). In contrast, in all of the patients treated with GnRH-a, the values of TmP/GFR increased after 6 months of treatment (the mean percentage change was 28.5%; range, 18.2-78.3%) and returned to the preadministration level at 12 weeks after stopping therapy. In these patients, both the values of TmP/GFR and the concentrations of serum Pi correlated significantly with circulating estradiol levels (r = -0.767, P < 0.01 and r = -0.797, P < 0.01, respectively), but the concentrations of serum corrected calcium did not correlate. Moreover, in the same patients, the levels of serum intact PTH decreased significantly (P < 0.05) after 6 months of treatment, but at 12 weeks after stopping therapy the trends of these levels varied among individual patients. These results suggest that estrogen could act directly to suppress sodium-dependent Pi reabsorption in the renal proximal tubules.

Gomisin A, a lignan component of Schizandora fruits, inhibits development of preneoplastic lesions in rat liver by 3'-methyl-4-dimethylamino-azobenzene.

The effects of gomisin A, a lignan component of Schizandra fruits, on development of preneoplastic lesions in the liver after a short-term (3 weeks) feeding of 3'-methyl-4-dimethyl-aminoazobenzene (3'-MeDAB) to male Donryu rats were investigated, and compared with the effects of phenobarbital. Gomisin A inhibited both increases of the level of glutathione-S-transferase placental form (GST-P) and the number and size of GST-P positive foci in the liver increased after treatment with 3'-MeDAB. Moreover, although the population of diploid nuclei was increased and that of tetraploid nuclei was decreased by pretreatment with 3'-MeDAB, gomisin A returned this to near the normal ploidy pattern. But phenobarbital increased the level of GST-P and the number and size of GST-P positive foci with little affect on the ploidy population changed by 3'-MeDAB. Thus, the effect of gomisin A on hepatocarcinogenesis was inhibitory in contrast with that of phenobarbital. This study suggests that gomisin A is a candidate for a chemopreventive drug inhibiting the promotion process in hepatocarcinogenesis.

Immunohistochemical and RT-PCR detection of Na+-dependent inorganic phosphate cotransporter (NaPi-2) in rat brain.

Expression of a renal Na+-dependent inorganic phosphate (Pi) cotransporter (NaPi-2) was studied in rat forebrain with reverse transcription and polymerase chain reaction (RT-PCR) and immunohistochemistry. RT-PCR analysis for total RNA from whole brain and sequencing of the PCR products showed expression of NaPi-2 mRNA in the brain. Immunohistochemical analysis revealed NaPi-2 staining in many nonpyramidal neurons of all six layers throughout neocortical areas and in neurons of proisocortical and periallocortical areas. NaPi-2-immunoreactive neurons were also detectable in the piriform cortex, hippocampal formation, caudate-putamen, amygdaloid nuclei and lateral geniculate nucleus. Furthermore, NaPi-2 staining was shown in ependymal cells and microvascular endothelial cells. The present results suggest that NaPi-2 is synthesized within the brain and involved in maintaining Pi homeostasis of certain neurons and/or the entire brain.

Deoxycholic acid as an endogenous risk factor for hepatocarcinogenesis and effects of gomisin A, a lignan component of Schizandra fruits.

Although hepatocarcinogensis has been reported to be promoted by exogenous administration of bile acids, the relation of endogenous bile acids to hepatocarcinogenesis is not completely understood. This study investigates the relationship between serum concentration of bile acids, the appearance of preneoplastic change, glutathione S-transferase placental form (GST-P)-positive foci in the liver of male Donryu rats which had been fed 0.06% 3'-methyl-4-dimethylamino-azobenzene (3'-MeDAB), and the effects of gomisin A, previously reported to inhibit the tumor promotion process. During the feeding of 3'-MeDAB for 5 weeks, the concentrations of serum bile acids were found to have increased significantly to several times the levels found at the start of the experiment. The increase of serum bile acids, especially deoxycholic acid (DCA), and the appearance of preneoplastic lesions, the number and area of GST-P-positive foci in the liver, were significantly inhibited by simultaneous oral administration of gomisin A (30 mg/kg). When DCA (100 mg/kg) was orally administered after an initiation by 3'-MeDAB, serum bile acids and preneoplastic changes were significantly increased, these increases were inhibited by combined feeding of 0.03% gomisin A in the diet. There were good correlations between the serum concentration of DCA and the number of GST-P-positive foci in the liver in both experimental protocols. These results confirm that DCA is an endogenous risk factor for hepatocarcinogenesis and suggest that anti-promoter effect of gomisin A is based on improving metabolism of bile acids, including DCA.

Depressed plasma activity of plasminogen or alpha2 plasmin inhibitor is not due to consumption coagulopathy in septic patients with disseminated intravascular coagulation.

We have attempted to determine whether depressed plasma plasminogen and alpha2 plasmin inhibitor (or alpha2 antiplasmin) activity is, as a result of consumption coagulopathy, a specific finding of disseminated intravascular coagulation (DIC) in septic patients. The hemostatic parameters of 139 septic patients (68 with DIC and 71 without DIC) were analyzed. Among the group as a whole, plasma activities of plasminogen and alpha2 plasmin inhibitor were significantly depressed in septic patients with DIC relative to those without DIC (P < 0.01 and P < 0.05, respectively). Notably, a significant correlation was observed between plasma levels of albumin and plasminogen activity, as well as between plasma levels of albumin and alpha2 plasmin inhibitor activity both in septic patients with DIC and those without DIC. However, no significant correlation was observed between plasma levels of plasmin-alpha2 plasmin inhibitor complex (PIC) and plasminogen activity, nor between PIC and alpha2 plasmin inhibitor activity either in septic patients with DIC or those without DIC. We concluded that depressed activity of plasminogen or alpha2 plasmin inhibitor is not as a result of consumption coagulopathy, but rather a result of low synthetic function of the liver in septic patients with DIC.

All-trans retinoic acid is partially effective against lipopolysaccharide-induced but not against tissue-factor-induced disseminated intravascular coagulation in rat models.

All-trans retinoic acid (ATRA) has been introduced to the management of acute promyelocytic leukemia (APL) as a differentiation treatment. This drug not only causes complete remission, but also improves disseminated intravascular coagulation (DIC) without adding anticoagulants in APL. We have attempted to determine whether ATRA is effective against DIC in rat models induced by tissue factor (TF) or lipopolysaccharide (LPS), because the anticoagulant effect of ATRA has been considered to induce thrombomodulin upregulation and TF downregulation on endothelial cells as well as on APL cells. In male Wistar rats, DIC was induced by a 4-h infusion of thromboplastin (3.75 U/kg) or lipopolysaccharide (30 mg/kg). The rats were given ATRA orally each day at a dose of 100 mg/kg per day for 1 week before the injection of TF or LPS in ATRA treatment groups, or given low molecular weight heparin (LMWH) 10 min before the injection of TF or LPS (200 U/kg, bolus intravenously) in LMWH treatment groups. No significant changes in hemostatic parameters or markers of organ dysfunction were caused by the ATRA administration, while DIC was significantly improved by LMWH in the TF-induced model. DIC was significantly improved by both ATRA and LMWH in the LPS-induced model. These findings suggested that ATRA was useful for treating DIC only in the LPS-induced model, and that drug efficacy should be carefully assessed because the agents used to induce DIC considerably influenced the outcome.

Beneficial effect of JTV-803, a new synthetic inhibitor of activated factor X, against both lipopolysaccharide-induced and tissue factor-induced disseminated intravascular coagulation in rat models.

We examined whether JTV-803, a specific activated factor X inhibitor independent of antithrombin III (ATIII), is effective against disseminated intravascular coagulation (DIC) in rat models induced by tissue factor (TF) or lipopolysaccharides (LPS). In male Wistar rats, DIC was induced by a 4 h infusion of thromboplastin (3.75 U/kg) or LPS (50 mg/kg). The rats were given JTV-803 (0.3 or 3 mg/kg, bolus intravenously) (JTV-803 groups) or low molecular weight heparin (LMWH groups) (200 U/kg, bolus intravenously) prior to an injection of TF or LPS. The results showed that JTV-803 was dose-dependently effective against DIC in both TF-induced and LPS-induced rat models. This anti-DIC effect of JTV-803 at higher doses was almost equivalent to that of LMWH in both types of DIC. Plasma ATIII activity was more prominent in the group treated with JTV-803 than in that treated with LMWH. None of rats died in the TF-induced DIC model with or without drug administration. On the contrary, seven of 22 rats died (mortality rate, 31.8%) in the LPS-induced DIC model without drug administration. Although the mortality rate of rats induced with LPS and treated with LMWH was quite high (6/16, 37.5%), none of the LPS-induced rats treated with JTV-803 died. These findings suggested that JTV-803 can treat both TF-induced and LPS-induced DIC models, and that this drug has greater potential in preserving ATIII and in improving the prognosis of DIC.

Daily pattern of energy metabolism in cirrhosis.

The daily pattern of energy expenditure and the oxidation rates of carbohydrates, fats, and protein were evaluated by indirect calorimetry in 18 control subjects (Group 1) and 34 cirrhotic patients who were divided into Groups 2a and 2b showing indocyanin green retention rates at 15 min of <30% and 30% or more, respectively. The ratio of resting energy expenditure to basal energy expenditure (%REE) was higher in the cirrhotic patients than in the controls at 8:30 AM and 2:30 PM. The oxidation rates of carbohydrates and fats under fasting conditions in Group 2b patients were respectively lower, and higher than in Group 1 and 2a patients. After the subjects ate, glucose became the substrate preferentially metabolized, and the proportion of fat metabolized was reduced from 82.9+/-5.1% to 43.9+/-21.9% and from 70.7+/-14.1% to 46.8+/-13.9% in the patients with advanced and less advanced cirrhosis, respectively, and from 59.4+/-27.2% to 48.4+/-18.5% in the controls. The fasting concentrations of non-esterified fatty acids in Group 2b were also significantly higher than those in the Group 1 and Group 2a patients. After eating, these concentrations fell and reached similar levels in the patients and controls. These data indicated that the patients with cirrhosis developed the catabolic state of starvation in the morning because of a lack of glycogen stores. Therefore, frequent meal supplementation to prevent early-onset starvation and energy deficiency may be advisable in such patients to maintain a well-nourished condition.

Saturable function of P-glycoprotein as a drug-efflux pump in multidrug-resistant tumour cells.

P-glycoprotein acts as an active drug-efflux pump in multidrug-resistant tumour cells. We studied the capacity of P-glycoprotein to extrude drugs from the cells. For nanomolar concentrations of vinblastine P388/ADR cells, which overexpress P-glycoprotein in the plasma membrane, accumulated vinblastine, at 37 degrees C for 30 min, to a much lower extent than the sensitive cells (P388/S), while in the micromolar range the cellular concentration was similar for both types of cells. When cells were incubated with a low (10 nM) or high concentration (1 microM) of vinblastine while energy deprived, the vinblastine concentration increased only in the resistant cells incubated with the low concentration of vinblastine, and this increased level was lowered to the level under the normal conditions by addition of glucose. In contrast, the cellular concentrations in other cases were increased to the normal level by glucose. After cells were loaded with the low concentration of vinblastine, the cellular vinblastine was extruded more rapidly from the resistant cells than from the sensitive cells. The courses of vinblastine efflux from the cells loaded with the high concentration of vinblastine were similar in both types of cells. NA-382, a reported P-glycoprotein inhibitor, effectively increased the intracellular vinblastine and inhibited the drug efflux only from multidrug-resistant cells, P388/ADR and AH66 cells, which were incubated with the low concentration of vinblastine. Cellular uptake of NA-382 was also less in P388/ADR cells than in P388/S cells in culture with 10 nM but not 1 microM of the agent, and this low level was reversed to the level in the sensitive cells by 10 microM vinblastine. These results indicate that P-glycoprotein as a drug-efflux pump works effectively under low extracellular concentrations of substrates, but does not under the high concentrations.

Selective bronchodilators from 1-(5'-oxohexyl)xanthines.

A series of twenty one 1-(5'-oxohexyl)xanthines substituted with alkyl chains at the N3 and N7 positions of the xanthine nucleus were prepared and their relaxant activity in guinea-pig isolated tracheal muscle and positive chronotropic activity in isolated right atrium of guinea-pig were compared. The tracheal relaxant activities were markedly increased with alkyl chain length at the N3 position, but decreased by the N7 alkylation. The positive chronotropic activities in the right atrium were increased by introduction of an n-propyl group at the N3 position but decreased by substitution of longer alkyl chains, and the action on the heart was diminished by N7 substitution. The activities of compounds on cAMP-phosphodiesterase (PDE) and binding of [3H]8-cyclopentyl-1,3-dipropylxanthine were measured in the homogenate of tracheal muscle and the membrane preparation of cerebral cortex, respectively. No relationship among tracheal muscle relaxant activity, cAMP-PDE inhibitory activity and adenosine antagonism of these xanthines was observed, and other action mechanisms should be considered for their relaxant activities. This study indicated that N3 alkylation is important for the selectivity for tracheal muscle, while the introduction of long alkyl chains such as n-butyl and n-pentyl groups at the N3 and N7 positions diminished the potency for the right atrium in guinea-pigs. 3-n-Pentyl- and 7-methyl-3-n-pentyl-1-(5'-oxohexyl)xanthines showed much higher bronchoselectivity than oxpentifylline and theophylline.

Effect of gamma-butyrobetaine on fatty liver in juvenile visceral steatosis mice.

We pharmacokinetically examined the effect of gamma-butyrobetaine, a precursor of L-carnitine, on the change of fatty acid metabolism in juvenile visceral steatosis (JVS) mice, which have systemic L-carnitine deficiency due to lack of L-carnitine transporter activity. The concentrations of total free fatty acid (FFA), palmitic acid and stearic acid in the liver of JVS mice were significantly higher than those in wild-type mice. After intravenous administration of gamma-butyrobetaine (50 mg kg(-1)), the concentration of L-carnitine in the plasma of JVS mice reached about twice that of the control level and levels in the brain, liver and kidney were also significantly increased, whereas those in wild-type mice hardly changed. Although the plasma concentrations of FFA in both types of mice were unchanged after administration of gamma-butyrobetaine, the concentrations of palmitic acid and stearic acid were significantly decreased. In particular, the liver concentration of FFA in JVS mice was decreased to the wild-type control level, accompanied by significant decreases in long-chain fatty acids, palmitic acid and stearic acid, whereas those in wild-type mice were not changed. These results suggest that gamma-butyrobetaine can be taken up into organs, including the liver, of JVS mice, and transformed to L-carnitine. Consequently, administration of gamma-butyrobetaine may be more useful than that of L-carnitine itself for treatment of primary deficiency of carnitine due to a functional defect of the carnitine transporter.

Inhibitory effects of psychotropic drugs on mexiletine metabolism in human liver microsomes: prediction of in vivo drug interactions.

Mexiletine, an anti-arrhythmic agent, is used for the control of ventricular arrhythmias and for neuropathic pain from cancer or diabetes mellitus. It is sometimes used together with psychotropic drugs in patients with depression, schizophrenia or sleep disorder. It is metabolized mainly by cytochrome P450 (CYP) 2 D 6 and, to a minor extent, by CYP1A2. To predict possible drug interactions between mexiletine and psychotropic drugs, the inhibitory effects of 14 psychotropic drugs (phenytoin, carbamazepine, fluvoxamine, paroxetine, fluoxetine, citalopram, sertraline, imipramine, desipramine, haloperidol, thioridazine, olanzapine, etizolam, and quazepam) on mexiletine metabolism in human liver microsomes were determined. Fluoxetine (Ki=0.6+/- 0.1 microM), sertraline (Ki=7.6+/- 0.8 microM) and desipramine (Ki=3.2+/- 0.5 microM) competitively inhibited the mexiletine p-hydroxylation in human liver microsomes. Thioridazine (Kis=0.5+/- 0.2 microM; Kii =3.6+/-1.6 microM) and paroxetine (Kis=1.7+/- 0.7 microM; Kii=3.6+/- 0.9 microM) exhibited a mixed-type inhibition (competitive and non-competitive) toward mexiletine p-hydroxylation in human liver microsomes. The changes of the in vivo clearance of mexiletine by the psychotropic drugs were predicted by 1+(I/Ki) using the in vitro Ki and unbound inhibitor concentrations in liver. The values were calculated as 2.4 for paroxetine, 5.5 for fluoxetine, 1.1 for sertraline, 2.8 for desipramine and 2.2 for thioridazine. In addition, paroxetine exhibited a mechanism-based inactivation with Ki=0.7 microM and Kinact=0.15 min(-1). The present study predicted the possibility of drug interactions between mexiletine and paroxetine, fluoxetine, desipramine, and thioridazine in clinical use.

Transcriptional regulation of the NPT2 gene by dietary phosphate.

Dietary phosphate (Pi) is an important regulator for renal Pi reabsorption. The type II sodium-dependent phosphate (Na/Pi) cotransporters (NPT2) are located at the apical membranes of renal proximal tubular cells and major functional transporters associated with renal Pi reabsorption. The yeast one-hybrid system was used to clone a transcription factor that binds to a specific sequence (Pi response element) in the promoter of the NPT2 gene. Two cDNA clones that encoded protein of the mouse transcription factor mu E3 (TFE3) were isolated. TFE3 may participate in the transcriptional regulation of the NPT2 gene by dietary Pi.

Effect of Choto-san, a Kampo medicine, on the cerebral blood flow autoregulation in spontaneously hypertensive rats.

To clarify the mechanism of the benefical effect of Choto-san on cerebral circulation in hypertensive patients, the influence of Choto-san on cerebral blood flow (CBF) during hemorrhagic hypotension was evaluated in 10- to 11-month-old spontaneously hypertensive rats. The lower limit of CBF autoregulation, defined as the mean arterial blood pressure at which CBF decreased by 10% of the baseline value, was dose-dependently lowered when Choto-san (0.5 - 2.0 g/kg per day, p.o.) was administered for 14 consecutive days. Uncariae Ramulus et Uncus (150 mg/kg per day, p.o.), one of the crude drug components of Choto-san, showed an effect equivalent to that of Choto-san. The action of Choto-san (2.0 g/kg per day, p.o.) or Uncariae Ramulus et Uncus on the autoregulatory response of cerebral vessels was eliminated by treatment with N(G)-nitro-L-arginine methyl ester (10 mg/kg, i.v.), an inhibitor of nitric oxide synthase. These results suggested that the activation of nitric oxide synthase by Uncariae Ramulus et Uncus contributed to at least part of the improvement in the cerebral circulation caused by Choto-san.