[Five-week intravenous toxicity study of montirelin hydrate (NS-3) in rats followed by 4-week recovery test]

A repeated dose toxicity study of montirelin hydrate (NS-3), a new drug for the treatment of disturbance of consciousness, was conducted in Sprague-Dawley rats. Male and female rats were given the drug intravenously for 5 weeks at doses of 0 (control), 0.05, 0.5, 5 and 50 mg/kg. After discontinuation of the treatment, a 4-week recovery test was also conducted in the 0, 0.5 and 50 mg/kg groups. No deaths related to the treatment were observed. Tremor was seen in the 50 mg/kg group. Polyuria was observed in the 5 and 50 mg/kg groups. There were decreases in body weight gain in the 0.5 mg/kg group and over of males, and in food consumption in all male dose groups and increase in water consumption in the 5 and 50 mg/kg groups. In blood chemical examination, decrease in triglyceride was observed in the 5 and 50 mg/kg groups of males. Urinalysis showed increase in urine volume in the 0.5 mg/kg group and over. Ophthalmoscopic and hematologic examinations failed to show any abnormalities attributable to the treatment. Pathological examination disclosed serous cell hypertrophy of the submandibular gland in all dose groups and increase in its organ weight in the 0.5 mg/kg group and over. The changes mentioned above were satisfactorily reversible except for the serous cell hypertrophy of the submandibular gland in the 50 mg/kg group. The decrease in food consumption and serous cell hypertrophy of the submandibular gland in the 0.05 mg/kg group were considered to be of no toxicological significance. These results show that the NOAEL of montirelin hydrate is 0.05 mg/kg for 5-week repeated dose toxicity in rats.

Respiratory burst and tyrosine phosphorylation by vanadate

We studied involvement of tyrosine-phosphorylated proteins in activation of NADPH oxidase in guinea pig neutrophils. Pervanadate, which is the oxidized form of orthovanadate, induced O2- production and protein tyrosine phosphorylation in neutrophils. O2- production induced by pervanadate was more sensitive to the tyrosine kinase-specific inhibitor, ST-638, as compared with the production induced by PMA. On the other hand, staurosporine more selectively inhibited PMA-induced O2- production than pervanadate-induced production. These results indicate that tyrosine kinase, not protein kinase C, is involved in pervanadate-induced O2- production. The tyrosine-phosphorylated proteins were detected in both the cytosol and membrane fractions prepared from pervanadate-induced neutrophils. In order to examine if tyrosine residues of some components of NADPH oxidase were directly phosphorylated, tyrosine-phosphorylated proteins were removed from solubilized membranes prepared from the pervanadate-stimulated neutrophils by immunoprecipitation with an anti-phosphotyrosine anti-body. NADPH oxidase activity in the solubilized membranes was not decreased by the treatment. These findings suggest that the components of NADPH oxidase are not tyrosine-phosphorylated by pervanadate treatment, that tyrosine phosphorylation may be involved in the signal transduction pathway of NADPH oxidase activation by pervanadate, and that this pathway is independent of the activation by protein kinase C.

Hyperphosphorylated p47-phox lost the ability to activate NADPH oxidase in guinea pig neutrophils

p47-phox is one of the cytosolic activation factors of NADPH oxidase in neutrophils and known to translocate to plasma membranes and function by protein kinase C-phosphorylation. In cytosol fraction, prepared from calyculin A-treated neutrophils, the activity of cytosolic factor to activate NADPH oxidase was more reduced than that from PMA-treated cells. But, p47-phox did not translocate to the membranes, even if p47-phox was hyperphosphorylated in the calyculin A-treated neutrophils. Such hyperphosphorylated p47-phox seemed to lose the activity to constitute NADPH oxidase complex.

Reduction of mono(ADP-ribosyl)ation of histones in rat testis by gonadotropin-testosterone system

Mono(ADP-ribose) synthetase activity in the nuclear fraction of immature rat testis was investigated in reference to the effect of testosterone. When the nuclear fraction was incubated with [32P] NAD in the presence of nicotinamide, an inhibitor of poly (ADP-ribose) synthetase, some proteins with a molecular mass of 14.4-21.5 kDa were ADP-ribosylated. In these proteins, H2B and H3 histones were found by sequencing 20 amino acids in the N-terminus. Their incorporations of ADP-ribose moiety were significantly decreased in immature rats at 4 hr after the subcutaneous injection of testosterone. Furthermore, the treatments with LH and FSH of the immature rats reduced mono(ADP-ribosyl)ations of H2B and H3 histones in a time-dependent manner. These results suggest that the testicular mono(ADP-ribose) synthetase activity is under the control of gonadotropin-testosterone system and is possibly related to differentiation of the testis.

Rapid genotyping of low density lipoprotein receptor knockout mice using a polymerase chain reaction technique

A new method for the rapid genotyping of low density lipoprotein receptor knockout mice is described. This method using a polymerase chain reaction (PCR) technique may be performed on small tissue biopsies, and represents a significant advantage in time over conventional genotyping by Southern blot analyses.

Overexpression of human lipoprotein lipase protects diabetic transgenic mice from diabetic hypertriglyceridemia and hypercholesterolemia

We investigated the role of the overexpression of lipoprotein lipase (LPL) in lipoprotein abnormalities in transgenic mice with streptozotocin-induced diabetes mellitus. Before the induction of diabetes, LPL activity was 4.6-fold in skeletal muscle and 2.0-fold higher in the heart in transgenic mice than in their nontransgenic littermates. LPL activity in skeletal muscles in diabetic nontransgenic mice and cardiac LPL activity in diabetic nontransgenic and transgenic mice were decreased. Body weights were similarly reduced, and no appreciable amount of adipose tissue was observed in diabetes in both groups. The plasma triglyceride level was lower in diabetic transgenic mice than in diabetic nontransgenic mice (33.2 +/- 22.5 versus 185.3 +/- 57.4 mg/dL). Induction of diabetes was associated with a significant increase in the plasma cholesterol level in nontransgenic mice (90.0 +/- 11.1 versus 163.9 +/- 39.3 mg/dL) but much less in transgenic mice. Our results indicate that overexpression of LPL in transgenic mice inhibited diabetes-associated hypertriglyceridemia and hypercholesterolemia but did not affect the loss of body weight induced by diabetes.

The mechanism of lactitol (NS-4) in inducing adrenomedullary proliferative lesion in rats

We used 13-week repeated oral administration of lactitol as part of a study to clarify the mechanism by which lactitol induces the proliferation of adrenomedullary chromaffin cells. There was a marked increase in urinary calcium (Ca) excretion even though the lactitol administration had no effect on the blood Ca level. A tendency for an increase in adrenal venous blood epinephrine (EPI) and norepinephrine (NE) concentrations was seen. Organ weight measurement of adrenal glands revealed a tendency for an increase in absolute weight and a significant increase in relative weight. Morphometric analysis of adrenomedullary chromaffin cells showed a tendency for an increased total cell volume and a decreased numerical density; but, there was no conspicuous change in the total cell number. Determinations of the anti-bromodeoxyuridine (BrdU) and antiproliferative cell nuclear antigen (PCNA) antibody-positive cell counts showed a tendency for an increased proliferation rate for adrenomedullary chromaffin cells. Electron microscopy showed a slight increase in the number of Golgi apparatuses in these cells. Because the marked increase in urinary Ca excretion was concomitant with morphological changes that suggested the hyperfunction of chromaffin cells in the adrenal medulla and a tendency for an increased cell proliferation rate, we assume that persistent hyperfunction of the adrenomedullary chromaffin cells, which was mediated by enhanced Ca absorption from the intestinal tract, may have induced proliferative lesion.

Nitroglycerin inhibits the phosphorylation of intermediate filament proteins rather than myosin light chain on porcine coronary artery sustained contraction

The smooth muscle relaxation induced by nitroglycerin is hypothesized to be mediated by an increase in the cytoplasmic concentration of guanosine 3',5'-monophosphate (cGMP) and subsequent dephosphorylation of the 20-kilodalton myosin light chain (MLC). We investigated this hypothesis in procine coronary arterial smooth muscle stimulated with histamine (3 microM) or K+ (30 mM). Stimulation of [32P]Pi-labeled muscle with histamine or K+ for 2 min resulted in a four- or 6.2-fold increase, respectively, in the incorporation of 32P into MLC. After 48 min of exposure to histamine, MLC phosphorylation decreased to the basal level and the phosphorylation of desmin, synemin, and of three unidentified cytosolic proteins was increased. K+ stimulation resulted in a sustained increase of MLC phosphorylation but had no effect on the phosphorylation of desmin, synemin, or the three unidentified cytosolic proteins. Application of nitroglycerin (1 microM) 48 min after histamine stimulation inhibited the phosphorylation of desmin, synemin, and the three cytosolic proteins. The sustained phase of histamine-induced contraction was also inhibited to a greater extent then the acute phase of histamine-induced contraction and both the acute and sustained phases of K(+)-induced contraction. These results suggest that MLC phosphorylation is required for both phases of K(+)-induced contraction, whereas phosphorylation of intermediate filament proteins is required for the sustained phase of histamine-induced contraction. Intermediate filament proteins, rather than MLC, may also be the target for the relaxant action of nitroglycerin during histamine-induced sustained contraction.

Cloning and structural analysis of the mouse apolipoprotein B mRNA editing protein gene

Mouse apolipoprotein B mRNA editing protein gene has been isolated and characterized. The amino acid sequences deduced from the exonic sequences of the gene showed 90, 70 and 68% identity to those of rat, human and rabbit, respectively. RNA blotting experiments demonstrated high expression in small intestine especially in the jejunum as a major 2.4 kb mRNA species. mRNA in other tissues including the liver is smaller in amounts and larger in size (3.1 kb) than the intestinal mRNA. The gene spans 12 kb and contains 5 exons and 4 introns. Sequencing of the 5'-flanking region revealed that a canonical TATA box is absent and the consensus recognition sequences for several transcription factors have been identified.

Evidence for the regulation of small intestinal Na+/glucose cotransporter by insulin

The small intestinal sodium dependent absorption of D-glucose has been known to be increased by diabetes mellitus. Furthermore, we previously showed that the enhanced activity of Na+/glucose cotransporter (SGLT1) was restored by the treatment with insulin. The present study was designed to investigate the mechanism by which diabetes mellitus and insulin regulated the activity of the small intestinal SGLT1. The acute diabetes at 2 weeks after the injection of streptozotocin increased the expression of SGLT1 protein in rat small intestinal brush border membrane vesicles without changing the mRNA level for SGLT1. In addition, we showed that the increased content of SGLT1 protein was restored by the subcutaneous treatment with insulin. In contrast, there was no change of the mRNA level for SGLT1 in diabetic and insulin-treated diabetic rats. These results suggest that rat intestinal SGLT1 activity is under the translational or posttranslational controls by insulin.

Cystic adventitial disease of the popliteal artery--a case of young boy

Cystic adventitial disease (CAD) of the popliteal artery (PA) is rare but one of the well-recognized causes of intermittent claudication. Now more than 200 case reports are available in the world, but there are only 6 cases younger than 15 years old. In this paper, we report a case of 14-year-old boy with CAD of the PA found by intermittent claudication. On examination, the pulses were not palpable below the right popliteal artery, and the angiography demonstrated about 1.5 cm-long obstruction of the right PA. We operated a resection of a cyst with artery, and replaced the autovein graft (V. saphena magna). Cyst contained mucoid degeneration-like ganglion. Two weeks after operation, the angiography showed no stenotic lesion, and follow-up at 4 years showed no symptoms.

Overexpression of human lipoprotein lipase increases hormone-sensitive lipase activity in adipose tissue of mice

An elevation of lipoprotein lipase (LPL) activity in adipose tissue is considered a possible cause of obesity. However, transgenic mice that overexpress the human LPL gene showed no increase in fat deposition as compared with controls. In the present study, we investigated effects of LPL on fat accumulation. Respiratory quotients and uptake of [3H] triolein by tissues (white and brown adipose tissue, and skeletal muscles) did not differ significantly for transgenic and non-transgenic mice. The mRNA levels of hormone-sensitive lipase (HSL) and HSL activity in adipose tissue during feeding were higher in LPL transgenic mice than in controls. Results suggest that the overexpression of LPL does not induce obesity by enhancing the hydrolysis of triglycerides in adipose tissue.

Induction of sustained expression of proto-oncogene c-fms by platelet-derived growth factor, epidermal growth factor, and basic fibroblast growth factor, and its suppression by interferon-gamma and macrophage colony-stimulating factor in human aortic medial smooth muscle cells

Vascular medial smooth muscle cells migrate, proliferate and transform to foam cells in the process of atherosclerosis. We have reported that the intimal smooth muscle cells express proto-oncogene c-fms, a characteristic gene of monocyte-macrophages, which is not normally expressed in medial smooth muscle cells. In the present study, we demonstrated that combinations of platelet-derived growth factor (PDGF)-BB and either epidermal growth factor (EGF) or fibroblast growth factor (FGF) induced high expression of c-fms in normal human medial smooth muscle cells to the level of intimal smooth muscle cells or monocyte-derived macrophages, whereas c-fms expression by PDGF-BB alone was 1/10 and both EGF and FGF had no independent effect on c-fms expression. By contrast, interferon (IFN)-gamma and macrophage colony-stimulating factor (M-CSF) suppressed the induction of c-fms expression. These results indicate that multiple growth factors and cytokines may play a role in the phenotypic transformation of medial smooth muscle cells to intimal smooth muscle cells in atherosclerotic lesions by altering c-fms expression.

[Perspective of gene therapy in hyperlipoproteinemia]

Several experimental trials are under way to correct the deficiency of LDL receptor function known as Familial Hypercholesterolemia (FH) that develops devastating atherosclerosis leading to premature fatal coronary occlusion. Recently, a 28-year-old FH homozygous woman has received ex vivo autologous liver transplantation after transduction with retroviral vector expressing functional LDL receptors. The outcome is partially successful but is still controversial because of an argument that the apparent small decrease in the total plasma cholesterol level is not necessarily caused by the correction of the LDL receptor expression. In addition to retrovirus, adenovirus vector and non-viral methods are being employed as potential tools for FH gene therapy.

[LDL-receptor-related protein]

The LDL-receptor-related protein is a multifunctional endocytotic receptor that clear apo E- and/or lipoprotein lipase-enriched lipoproteins, proteases such as alpha 2-macroglobulin plasminogen and activator inhibitor-1 (PAI-1), Pseudomonas exotoxin A and probably vitellogenin from blood circulation. Its role in plasma chylomicron remnant clearance has been postulated, and recently has been demonstrated by using its inhibitor; receptor-associated protein (RAP) in LDL receptor knockout mice.

Activation mechanism of NADPH oxidase by SDS in intact guinea pig neutrophils

It is well known that sodium dodecyl sulfate (SDS) activates NADPH oxidase in a cell-free system independently of protein kinase C (PKC). However, in intact neutrophils, direct evidence has never been presented to show that O2- production by SDS is actually due to the NADPH oxidase activation observed in the cell-free system. So, in this paper, we investigated the activation mechanism by SDS in intact guinea pig neutrophils. We previously reported that hypotonic treatment reversibly enhanced O2- production stimulated by PKC activators in intact neutrophils (M. Hiura et al., 1991, Arch. Biochem. Biophys. 291, 31-37). In this paper, SDS also significantly stimulated O2- production in the intact cells under the hypotonic condition. This enhancement was gradual and was PKC inhibitor resistant. Furthermore, phosphorylation of the 46-kDa protein, one of cytosolic activation factors, was not detected by autoradiography of two-dimensional electrophoresis. Translocation of cytosolic activation factors was demonstrated by a decrease in the activity of the factors remained in the cytosol. In the presence of SDS, addition of 1-oleoyl-2-acetylglycerol, a PKC activator, further enhanced O2- production and translocation of the cytosolic activation factors. On the other hand, SDS remarkably increased membrane fluidity in intact neutrophils as well as in the cell-free system. These results indicate that activation of NADPH oxidase by SDS in intact neutrophils seems to be partly due to the same mechanism observed in cell-free activation, and that SDS alone slightly activates the oxidase and other stimulation, such as hypotonic and/or PKC activator treatments, is required for significant activation. The increase in the membrane fluidity may be one of the activation mechanisms of NADPH oxidase by SDS.

Asialoglycoprotein receptor deficiency in mice lacking the minor receptor subunit

The asialoglycoprotein receptor is an abundant heterooligomeric endocytic receptor that is predominantly expressed on the sinusoidal surface of the hepatocytes. Proposed physiological and pathophysiological functions ascribed to this hepatic lectin (HL) include the removal of desialylated serum glycoproteins and apoptotic cells, clearance of chylomicron remnants, and a role as a homing receptor for lymphatic and metastatic cells. The assembly of two homologous subunits, HL-1 and HL-2, is required to form functional, high affinity receptors on the cell surface. However, the importance of the individual subunits for receptor transport to the cell surface has been controversial. To explore the significance of the minor HL-2 subunit for receptor expression and function in vivo, we have disrupted the HL-2 gene in mice. Homozygous HL-2-deficient animals are superficially normal. However, HL-1 expression in the liver is greatly reduced, indicating that HL-2 may promote HL-1 stability. Although these mice are completely unable to clear asialoorosomucoid, a high affinity ligand for asialoglycoprotein receptor, they do not accumulate desialylated glycoproteins or lipoproteins in their circulation.

[13-week oral toxicity study of lactitol (NS-4) in rats followed by 5-week recovery test]

Twenty male and 20 female Slc : SD rats were orally given lactitol, a hepatic encephalopathy drug, for 13 weeks at doses of 0, 0.625, 2.5 or 10 g/kg/day. A 5 week recovery test was conducted after the discontinuation of the drug treatment. Soft stool and decreased food consumption were seen in the 2.5 and 10 g/kg groups. In the 10 g/kg group, there were diarrhea, soiled fur, abdominal distention, salivation, piloerection, decreased body weight gain and increased water consumption. Urinalysis showed decreased urine volume and K+ excretion in the 10 g/kg group. In this dose group, biochemical examination showed decreased ALP, total cholesterol, triglyceride, glucose, Ca, Na+, Cl- and total protein. In the pathological examination, the cecum weight was increased in all dose groups. In the 2.5 and 10 g/kg groups, cecum distention with mucosal hyperplasia was observed. The adrenal weight was increased in the 10 g/kg group and hypertrophy of zona fasciculata of adrenal gland were seen in the 2.5 and 10 g/kg groups. The thymic weight was decreased in the 10 g/kg group. Ophthalmoscopic and hematologic examinations failed to reveal any drug induced changes. The increased cecum weight in the 0.625 g/kg group was regarded as toxicologically insignificant because of the failure of the association with any clinical or morphological findings. The above mentioned changes were satisfactorily reversible except for those in the cecum. Based on the results obtained, the NOAEL of this study was suggested to be 0.625 g/kg/day.

Dual effects of forskolin on glucose utilization in cultured fibroblasts, as observed with the use of glucose analogs

It is well known that forskolin suppresses glucose transport in cell membranes. In the present study, however, we indicated a different effect of forskolin on the uptake of radioactive 2-deoxy-D-glucose (2-DG) by cultured fibroblasts between the values measured in the presence of unlabeled 2-DG and those measured in the presence of unlabeled glucose. In the former case, the uptake was inhibited by forskolin. On the contrary, [3H] 2-DG uptake in the presence of unlabeled glucose was increased by forskolin. These results suggest that the metabolic difference between the two sugars is involved in the above-mentioned difference in the effect of forskolin. This paper presents that forskolin has stimulatory effect on glycolysis in addition to an inhibitory effect on glucose transporter. The findings seem to be of another interest to indicate the relationship between membrane transport and subsequent intracellular metabolism of glucose.

Inhibition of hepatic chylomicron remnant uptake by gene transfer of a receptor antagonist

The low density lipoprotein receptor-related protein (LRP) has been proposed to mediate in concert with the LDL receptor (LDLR) the uptake of dietary lipoproteins into the hepatocytes. This hypothesis was tested by transient inactivation of LRP in vivo. Receptor-associated protein (RAP), a dominant negative regulator of LRP function, was transferred by an adenoviral vector to the livers of mice lacking LDLR (LDLR-/-). The inactivation of LRP by RAP was associated with a marked accumulation of chylomicron remnants in LDLR-/- mice and to a lesser degree in normal mice, suggesting that both LDLR and LRP are involved in remnant clearance.

Inhibitory effect of some triterpenoid saponins on glucose transport in tumor cells and its application to in vitro cytotoxic and antiviral activities

The effects of some triterpenoid saponins on glucose transport in Ehrlich ascites tumor (EAT) cells were examined by measuring 2-deoxy-D-glucose (2-DG) uptake. The correlation of the effects with those on the growth of a human T-cell line (MT-4) and the replication of human immunodeficiency virus in MT-4 cells was also studied. Chikusetsusaponin Ia isolated from rhizomes of Panax japonicus C. A. Meyer (Araliaceae) inhibited the 2-DG uptake (IC50 = 76.3 microM) in a competitive fashion with respect to 2-DG (Ki = 0.32 mM) and the growth of MT-4 cells with CC50 of 84.4 microM, whereas it did not show any significant anti-HIV-1 activity. In contrast, zingibroside R1 isolated from rhizomes of Panax zingiberensis Wu et Feng (Araliaceae) showed some anti-HIV-1 activity, which was found to be superior to that of glycyrrhizin, as well as the inhibitory effects on the 2-DG uptake by EAT cells (IC50 = 91.3 microM) and the growth of MT-4 cells (CC50 = 46.2 microM).