Osteoclastogenesis inhibitory factor/osteoprotegerin reduced bone loss induced by mechanical unloading.

Skeletal unloading resulting from space flight and prolonged immobilization causes bone loss. Such bone loss ostensibly results from a rapid increase in bone resorption and subsequent sustained reduction in bone formation, but this mechanism remains unclear. Osteoclastogenesis inhibitory factor/osteoprotegerin (OCIF/OPG) is a recently identified potent inhibitor of osteoclast formation. We studied effects of OPG administration on tail-suspended growing rats to explore the therapeutic potential of OPG in the treatment and prevention of bone loss during mechanical unloading, such as that which occurs during space flight. Treatment with OPG in tail suspension increased the total bone mineral content (BMC g) of the tibia and femur and the total bone mineral density (BMD g/cm2) of the tibia. Moreover, treatment with OPG prevented reduction not only of BMC and BMD, but also of bone strength occurring through femoral diaphysis. Treatment with OPG in tail-suspended rats improved BMC, BMD and bone strength to levels of normally loaded rats treated with vehicle. Treatment with OPG in normally loaded rats significantly decreased urinary excretion of deoxypyridinoline, but the effect of OPG in tail suspension was unclear. These results indicate that OPG may be useful in inhibiting bone loss-engendered mechanical unloading.

Antidiabetic activity of the rhizoma of Anemarrhena asphodeloides and active components, mangiferin and its glucoside.

The antidiabetic activity of the rhizoma of Anemarrhena asphodeloides was investigated in KK-Ay mice, an animal model of genetic type 2 diabetes. The water extract of the rhizoma (AA) (90 mg/kg) reduced blood glucose levels from 570 +/- 29 to 401 +/- 59 mg/dl 7 h after oral administration (p<0.05) and also tended to reduce serum insulin levels in KK-Ay mice. AA-treated KK-Ay mice had significantly reduced blood glucose levels in an insulin tolerance test. Based on these results, the antidiabetic mechanism of AA may be due to decreased insulin resistance. In addition, the active components of AA were confirmed to be mangiferin and its glucoside.

Case report: pulmonary embolism from thrombosis in a duplicated inferior vena cava developing after an electrophysiologic procedure.

Duplicated inferior cava (IVC) is an anomaly we rarely encounter during electrophysiologic procedures. We report a case with duplicated IVC who developed thrombosis of the left IVC following an electrophysiologic procedure, which resulted in an asymptomatic pulmonary embolism. It is speculated that several catheters placed in the torturous route through the left IVC caused either endothelial damage to the vessel wall, or hemostasis in the relatively narrow portion of the vessel, resulting in thrombus formation. Since the prevalence and characteristics of thrombo-embolic complications during electrophysiologic procedures in patients with a duplicated IVC remain unknown, we believe this case should be reported.

Antioxidant alpha-tocopherol ameliorates glycemic control of GK rats, a model of type 2 diabetes.

We have shown recently that oxidative stress by chronic hyperglycemia damages the pancreatic beta-cells of GK rats, a model of non-obese type 2 diabetes, which may worsen diabetic condition and suggested the administration of antioxidants as a supportive therapy. To determine if natural antioxidant alpha-tocopherol (vitamin E) has beneficial effects on the glycemic control of type 2 diabetes, GK rats were fed a diet containing 0, 20 or 500 mg/kg diet alpha-tocopherol. Intraperitoneal glucose tolerance test revealed a significant increment of insulin secretion at 30 min and a significant decrement of blood glucose levels at 30 and 120 min after glucose loading in the GK rats fed with high alpha-tocopherol diet. The levels of glycated hemoglobin A1c, an indicator of glycemic control, were also reduced. Vitamin E supplementation clearly ameliorated diabetic control of GK rats, suggesting the importance of not only dietary supplementation of natural antioxidants but also other antioxidative intervention as a supportive therapy of type 2 diabetic patients.

Vitamin D is an important factor in estrogen biosynthesis of both female and male gonads.

In the present study, the role of vitamin D in the regulation of estrogen synthesis in gonads was investigated. Vitamin D receptor null mutant mice showed gonadal insufficiencies. Uterine hypoplasia and impaired folliculogenesis were observed in the female, and decreased sperm count and decreased motility with histological abnormality of the testis were observed in the male. The aromatase activities in these mice were low in the ovary, testis, and epididymis at 24%, 58%, and 35% of the wild-type values, respectively. The gene expression of aromatase was also reduced in these organs. Elevated serum levels of LH and FSH revealed hypergonadotropic hypogonadism in these mice. The gene expressions of estrogen receptor alpha and beta were normal in gonads in these mice. Supplementation of estradiol normalized histological abnormality in the male gonads as well as in the female. Calcium supplementation increased aromatase activity and partially corrected the hypogonadism. When the serum calcium concentration was kept in the normal range by supplementation, the aromatase activity in the ovary increased to 60% of the wild-type level, but LH and FSH levels were still elevated. These results indicated that vitamin D is essential for full gonadal function in both sexes. The action of vitamin D on estrogen biosynthesis was partially explained by maintaining calcium homeostasis; however, direct regulation of the expression of the aromatase gene should not be neglected.

Effects of ginseng radix on sugar absorption in the small intestine.

Ginseng radix (GR) is often used in traditional Japanese kampo medicine. We studied the effect of GR on glucose and maltose transport in rat and human duodenal mucosa by Ussing's method, and on smooth muscle movement in rat duodenal muscle by Magnus' method. GR inhibited absorption of glucose or maltose in rat and human duodenal mucosa, but increased duodenal muscle movement. It suggests that the inhibition of sugar absorption by GR is more dominant than enhancement of duodenal muscle movement by GR.

Antidiabetic mechanism of Bakumondo-inshi.

To determine the antidiabetic mechanism of Bakumondo-inshi (BI), we examined its effects on glucose absorption, alpha-glucosidase activity, sodium-dependent glucose transporter and facilitative glucose transporter isoform 5 (GLUT5) in small intestine. The oral administration of BI into KK-Ay mice caused a significant decrease in the glucose absorption in small intestine. The small intestine content of active glucose transporter isoform (SGLUT) protein content from KK-Ay mouse significantly decreased in the BI-treated KK-Ay mice compared to that in the controls. However, the small intestine content of facilitative glucose transporter isoform, GLUT5 protein content did not change. The alpha-glucosidase activity in small intestine significantly decreased in the BI-treated KK-Ay mice. These results suggest that the antidiabetic effect of BI is derived, at least in part, from a decrease of glucose absorption in small intestine , due to the reduction of SGLUT protein content in total membrane of the small intestine and the reduction of alpha-glucosidase activity. Because of its therapeutic mechanism, BI could be a new category of therapeutic agent for non-insulin dependent diabetic mellitus.

Metabolic inhibition impairs ATP-sensitive K+ channel block by sulfonylurea in pancreatic beta-cells.

The effect of metabolic inhibition on the blocking of beta-cell ATP-sensitive K+ channels (KATP channels) by glibenclamide was investigated using a patch-clamp technique. Inhibition of KATP channels by glibenclamide was attenuated in the cell-attached mode under metabolic inhibition induced by 2,4-dinitrophenol. Under a low concentration (0.1 microM) of ATP applied in the inside-out mode, KATP channel activity was not fully abolished, even when a high dose of glibenclamide was applied, in contrast to the dose-dependent and complete KATP channel inhibition under 10 microM ATP. On the other hand, cibenzoline, a class Ia antiarrhythmic agent, inhibits KATP channel activity in a dose-dependent manner and completely blocks it, even under metabolic inhibition. In sulfonylurea receptor (SUR1)- and inward rectifier K+ channel (Kir6.2)-expressed proteins, cibenzoline binds directly to Kir6.2, unlike glibenclamide. Thus, KATP channel inhibition by glibenclamide is impaired under the condition of decreased intracellular ATP in pancreatic beta-cells, probably because of a defect in signal transmission between SUR1 and Kir6.2 downstream of the site of sulfonylurea binding to SUR1.

[Standard versus long-term prednisolone with sairei-to for initial therapy in childhood steroid-responsive nephrotic syndrome: a prospective controlled study].

The most appropriate initial treatment for children with steroid-responsive nephrotic syndrome is controversial. Initial treatment with 18-week prednisolone and the Chinese herbal medicine. Sairei-to, may prevent subsequent relapse. To determine whether similar results can be obtained with a combination of just initial 8-week prednisolone and Sairei-to, we compared the effects of such treatment with those of treatment with 18-week prednisolone and Sairei-to in 196 children with steroid-responsive nephrotic syndrome. The patients were randomly assigned to receive 8-week (group 1) or 18-week (group 2) prednisolone for the initial therapy. All patients received Sairei-to for 2 years in addition to prednisolone. Eighty-eight of the 98 patients in group 1 and 83 of the 98 patients in group 2 completed their trial. At entry, the two groups of patients did not differ in their clinical and laboratory findings. During the 2-year trial, 62 group 1 patients (70%) and 54 group 2 patients (65%) had relapses, and 19 group 1 patients (21%) and 20 group 2 patients (24%) had frequent relapses. The present study demonstrates that a combination of initial 8-week prednisolone and 2-year Sairei-to is effective in children with steroid-responsive nephrotic syndrome.

Antidiabetic effect of seishin-kanro-to in KK-Ay mice.

The hypoglycemic effect of Seishin-kanro-to (SK) was investigated in KK-Ay mice, one of the non-insulin dependent diabetic mellitus types. SK (1700 mg/kg) reduced the blood glucose of KK-Ay mice from 557 +/- 17 to 383 +/- 36 mg/100 ml 7 hours after single oral administration (P < 0.001). SK also decreased the blood glucose and improved glucose tolerance 5 weeks after repeated administration in KK-Ay mice. These results support, therefore, the use of SK in patients with diabetes and confirm its role as a traditional medicine. In addition, the active plants of SK were identified as the rhizome of Anemarrhena asphodeloides Bunge and the radix of Rehmannia glutinosa Liboschitz.

[A prospective controlled study of sairei-to in childhood IgA nephropathy with focal/minimal mesangial proliferation. Japanese Pediatric IgA Nephropathy Treatment Study Group].

To determine the effect of the Chinese herbal medicine, Sairei-to (TJ-114) in children with newly diagnosed IgA nephropathy showing focal/minimal mesangial proliferation, we undertook a prospective controlled study. One hundred and one patients were randomly assigned to receive Sairei-to for 2 years (group 1) or no drug for 2 years (group 2). Forty-six of the 50 patients in group 1 and 48 of the 51 patients in group 2 completed their trial. At entry, the two groups of patients did not differ in the clinical, laboratory and pathologic findings. At the end of the trial, urinary protein excretion and hematuria were significantly reduced in group 1, but were unchanged in group 2. Twenty-one group 1 patients (46%) had normal urine, but only 5 group 2 patients (10%) had normal urine at the end of the trial (p < 0.001). Blood pressure and creatinine clearance were normal at the end of the trial in all but one group 2 patient, who developed chronic renal failure. The present study demonstrates that 2-year Sairei-to treatment early in the course of disease is effective in children with IgA nephropathy showing focal/minimal mesangial proliferation.

Growth hormone increases serum 1,25-dihydroxyvitamin D levels and decreases 24,25-dihydroxyvitamin D levels in children with growth hormone deficiency.

The influence of growth hormone (GH) on calcium-phosphorus metabolism and modulation of vitamin D metabolism has been demonstrated, but the mechanism remains unclear. We investigated the effect of a 6-month course of GH therapy on vitamin D and mineral metabolism in twelve GH-deficient children. Before GH therapy, levels of vitamin D metabolites and other biochemistry data were within normal ranges. All patients responded to GH therapy with increased growth velocity. 1,25-Dihydroxyvitamin D levels increased after 1 month of treatment and remained at these higher levels, with a significant increase found at 3 months (P < 0.05), whereas 24,25-dihydroxyvitamin D levels were decreased at 1 and 3 months, the latter being a significant decrease (P < 0.05), and then returned to the baseline levels at 6 months. 25-Hydroxyvitamin D levels did not change significantly. A significant increase in serum insulin-like growth factor-I (IGF-I) levels occurred during the 6 months of treatment (1 month, P < 0.01; 3 and 6 months, P < 0.001). Serum parathyroid hormone (PTH) levels decreased significantly at 3 and 6 months (3 months, P < 0.01; 6 months, P < 0.05). Serum calcium and phosphorus levels did not change significantly. Significant increases were found in the urinary calcium/urinary creatinine ratio (3 and 6 months, P < 0.05) and the percent tubular reabsorption of phosphorus levels (1 and 3 months, P < 0.05). The results of this study confirmed the actions of GH on renal tubules with increases in calcium excretion and phosphorus reabsorption, and indicate that the action of GH on modulating vitamin D metabolism may be IGF-I mediated, not PTH mediated.

Effect of ginseng radix on GLUT2 protein content in mouse liver in normal and epinephrine-induced hyperglycemic mice.

The oral administration of the water extract of Ginseng Radix (GR) to normal and epinephrine-induced hyperglycemic mice caused a significant decrease in the blood glucose level 4 h after its administration. The hepatic content of facilitative glucose transporter isoform 2, liver type glucose transporter (GLUT2) protein content from mouse liver significantly increased in the orally GR-treated normal and epinephrine-induced hyperglycemic mice compared to that in the controls. These results suggest that the hypoglycemic activity of GR is presumably due, at least in part, to the increment of GLUT2 protein content.

Kir2.2v: a possible negative regulator of the inwardly rectifying K+ channel Kir2.2.

We have cloned the human genes encoding the inwardly rectifying K+ (Kir) channel subunits, Kir2.2 (hKir2.2) and its variant, termed hKir2.2v. When expressed in Xenopus oocytes, hKir2.2 produced strong inwardly rectifying K+ currents, whereas the expression of hKir2.2v did not elicit significant currents. Coexpression of hKir2.2v with hKir2.2 showed an hKir2.2v inhibition of hKir2.2 K+ currents, indicating that it acts as a negative regulator of hKir2.2 channel activity. Mutational analysis of hKir2.2v and studies of chimeras between hKir2.2 and hKir2.2v suggest that the intracellular C-terminal region of hKir2.2v participates in the negative regulation of the hKir2.2v channel activity.

Effect of polygonati rhizoma on blood glucose and facilitative glucose transporter isoform 2 (GLUT2) mRNA expression in Wistar fatty rats.

The intraperitoneal administration of the methanol extract of Polygonati Rhizoma (OM) to Wistar fatty rats caused a significant decrease in the blood glucose level 4h after its administration at 800 mg/kg (p < 0.01). The hepatic content of facilitative glucose transporter isoform 2, liver type glucose transporter (GLUT2) mRNA content from rat liver significantly decreased in the intraperitoneally OM-treated rats compared to that in the controls (p < 0.01). These results suggest that the hypoglycemic effect of OM is presumably due, at least in part, to the reduction of GLUT2 mRNA expression. Because of this unique therapeutic mechanism, OM could be a new category of therapeutic agent for non-insulin-dependent diabetes mellitus.

Molecular diversity and functional characterization of voltage-dependent calcium channels (CACN4) expressed in pancreatic beta-cells.

Dihydropyridine-sensitive voltage-dependent calcium channels (VDCC) play a crucial role in insulin secretion. We recently have cloned a human alpha 1-subunit of the VDCC expressed in pancreatic beta-cells, designated CACN4. In this study we have isolated complementary DNAs encoding two forms of rat CACN4 (rCACN4A and rCACN4B) from a rat insulinoma RINm5F complementary DNA library. Rat CACN4A is a protein of 2203 amino acids and is the rat homolog of human CACN4, whereas rCACN4B lacks 535 amino acids in the carboxyl-terminal region, probably due to alternative splicing. We have found two additional variations, one in the intracellular loop between repeats I and II and the other in the extracellular region between the third and fourth segments of repeat IV. Reverse transcriptase-polymerase chain reaction analysis of rat pancreatic islet messenger RNA reveals that these variants are present in pancreatic islets. In addition, whole-cell voltage-clamp recordings of Chinese hamster ovary cells stably expressing the alpha 1-subunit (rCACN4A or rCACN4B) with or without the calcium channel beta 2-subunit show that coexpression of rCACN4A with the beta 2-subunit or rCACN4B with the beta 2-subunit elicits L-type VDCC currents, whereas expression of the alpha 1-subunit alone does not, indicating that CACN4 can associate functionally with the beta 2-subunit and that the beta-subunit is essential for functional expression of CACN4. These results suggest that there are various subtypes of CACN4 expressed in pancreatic beta-cells, and that both rCACN4A and rCACN4B can function as VDCC. Furthermore, the present study suggests that the expression of the beta-subunit as well as the alpha 1-subunit may participate in the regulation of insulin secretion.

Suppressive effects of polygonati rhizoma on hepatic glucose output, GLUT2 mRNA expression and its protein content in rat liver.

The intraperitoneal administration of the methanol extract of Polygonati Rhizoma (OM) into normal rats caused a significant decrease in the blood glucose level at 4 h after its administration of 800 mg/kg (P < 0.01), but not the serum insulin level. Using the perfused rat liver in vitro, a significant decrease of the hepatic glucose output was observed by the infusion of OM (P < 0.05 at 250 micrograms/ml OM). In addition, the hepatic content of facilitative glucose transporter isoform 2 (GLUT2) mRNA and its protein content in the total membrane fraction from rat liver significantly decreased in the intraperitoneally OM-treated rats when compared to that in the controls (mRNA P < 0.01, protein P < 0.001). On the other hand, OM (500 micrograms/ml) exhibited no apparent stimulatory effect on the insulin secretion from the isolated rat pancreatic islets. These results suggest that the hypoglycemic effect of OM is derived, at least in part, from the decrease in hepatic glucose output, due presumably to the reduction of GLUT2 mRNA expression and its protein content in total membrane of the liver, and that because of its unique therapeutic mechanism, OM could be a new category of therapeutic agent for non-insulin-dependent diabetes mellitus.

Secretion of osteocalcin and its propeptide from human osteoblastic cells: dissociation of the secretory patterns of osteocalcin and its propeptide.

Specific immunoassay systems for intact human osteocalcin (I-OC) and its 26-residue propeptide have been newly developed to assess their usefulness as biochemical markers of bone metabolism. Using human cultured osteoblastic periosteal cells, we monitored 24 h secretion of these molecules from the osteoblastic cells and also examined the deposition of Ca, P, and I-OC on the extracellular matrix. At day 5, both I-OC and its propeptide were secreted by osteoblastic cells in a concentration-dependent manner by treatment with 1,25-(OH)2D3. This propeptide was not detected in the serum of adult subjects but was detected in the serum of normal children, which confirmed this in vitro result of propeptide secretion. The secretion of I-OC into medium transiently decreased at day 11, when the rapid accumulation of I-OC, Ca, and P, namely mineralization, was observed on the extracellular matrix of osteoblastic cells, although secretion of the propeptide constantly increased throughout the culture period. Therefore, the ratio of the amount of propeptide to I-OC in the supernatant markedly increased when mineralization started. These data demonstrate the superior specificity of propeptide as a marker of osteoblastic function in vitro compared with I-OC and that monitoring the changes in propeptide to I-OC ratios in the culture supernatant may be useful for predicting the timing of mineralization on the extracellular matrix of osteoblastic cells.

Growth hormone (GH) treatment in achondroplasia.

Achondroplasia is one of the most commonly known types of skeletal dysplasia in the adult leading to short stature. Before beginning growth hormone (GH) treatment of short stature in patients with achondroplasia, we evaluated their growth pattern and their hypothalamic-pituitary function, including GH secretion. We studied 22 patients with achondroplasia (7 males and 15 females: age range, 3 to 12 years). The z-score of their height at admission was -5.4 +/- 1.2 (mean +/- SD), and that of their annual height gain before admission was -3.1 +/- 1.3 (mean +/- SD). GH response to provocative tests was normal in all patients except five: four showed subnormal (< 10 ng/ml) response to L-Dopa stimuli, and one patient showed subnormal (< 20 ng/ml) response to GRF stimuli. The mean GH concentration during sleep was found to be low (< 5 ng/ml) in three patients. These three patients were suspected to have latent GH deficiency, as they also showed a markedly low IGF-1 level and marked delay of bone age. LH, FSH, TSH, and cortisol response to provocative tests were normal in all the patients. We treated this group of patients with recombinant human GH (1 IU/kg/week). In 18 patients who were treated with GH for more than 6 months, height velocity during GH therapy was significantly increased compared to that before GH therapy (4.1 +/- 0.8 cm/year vs 7.2 +/- 1.4 cm/year). We conclude that parameters reflecting hypothalamic-pituitary function, particularly GH secretion, should be examined in achondroplasia patients, and that GH treatment may be beneficial in the treatment of short stature in achondroplasia.