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Biomedical subjects

K Ohya

Publications and source records attributed to K Ohya.

At least 109 records · Page 6Linked to original sources
PubMed1995

Osteoporosis-like changes in Walker carcinoma 256-bearing rats, not accompanied with hypercalcemia or parathyroid hormone-related protein production.

Walker carcinoma 256 (W256) was reported to induce hypercalcemia dependent on bone metastasis and/or parathyroid hormone-related protein (PTHrP) in the rat, providing a model of the humoral hypercalcemia of malignancy. In this study, after the subcutaneous inoculation of cells of the W256/S line, which is maintained in this laboratory, into young female Wistar Imamichi rats (6 weeks old), serum calcium and phosphorus levels changed only within the control range, whereas serum alkaline phosphatase activity and urinary calcium level significantly increased and urinary phosphorus decreased during the tumor growth, resulting in hypercalciuria and hypophosphaturia. W256/S did not express PTHrP-mRNA, whereas LLC-W256 cells did express it. Serum PTHrP level was not changed in W256/S-bearing rats. Osteoporosis-like changes, bone weight loss, low contents of bone calcium and phosphorus, and a decrease in the bone mineral density (BMD), were observed in the femur 14 days after the tumor inoculation. There was a pronounced decrease in the serum 17 beta-estradiol level during the tumor growth. The reduction of BMD of femurs in W256/S-bearing rats was significantly inhibited by treatment with salmon calcitonin or 17 beta-estradiol. On the basis of these results, W256/S carcinoma-bearing rats seem to be a useful model for osteoporosis of hypoovarianism.

Animals↗
PubMed1995

[Physiology and pharmacology of hard tissues--effect of chemicals on the formation and the resorption mechanism of tooth and bone].

This review described the effects of several drugs on the formation and the resorption mechanism of tooth and bone. The enamel formed during high fluoride exposure showed marked hypocalcification, and the organic substances appeared on the incisors in these regions. Such changes following fluoride administration appear to indicate an inhibition of the mineral deposition and/or an inhibition of organic matrix withdrawal. The successive bisphosphonate (HEBP) injections reduced both the progress of the mineral deposition and the formation of the enamel matrix. Colchicine showed a remarkable inhibitory effect on the matrix-forming cells of the dentin and enamel in teeth through its striking inhibitory action on the cytoskeletal system and secretary function. The dentin formation in rabbit and rat incisor dentin was reduced markedly. Colchicine induced reparative dentinogenesis in dental pulp and ectopic calcification in the bone marrow. Both sodium salicylate and aspirin reduced dentin formation through a mechanism that reduces the incorporation of collagen precursors into odontoblasts. Sodium salicylate also inhibited the growth of the upper jaw and tibia in rats. The recruitment of osteoclast-like multinucleated cells was inhibited by sodium salicylate in vitro. A pharmacological approach for studying the formation and resorption mechanism of hard tissue is useful tool for developing hard tissue research.

Animals↗
PubMed1995

[Study on cadmium-induced metallothionein-like protein in bone marrow of rabbit].

It has been recognized that metallothionein (MT) is a low molecular-weight protein and can be induced by heavy metals in several organs. Most studies on MT focus on the liver and kidney, and little is known about MT in the bone marrow. In the present study, the characterization of the MT-like protein in bone marrow of rabbits was investigated after the injection of CdCl2. A dose of 8 x 10(-5) mol/kg CdCl2 was injected subcutaneously into Japanese White Rabbits (male, 3.5 kg) for five days. Twenty-four hours after the last CdCl2 injection, the bone marrow, liver and kidney were removed immediately and frozen. The fractions of metal-binding protein were obtained by gel filtration (Sephadex G-75) of cytosol from the tissues of Cd-treated rabbit. They were heat-stable and low molecular-weight (under 10 kDa) proteins. They had high absorption at 250 nm. These observations suggest that the injection of CdCl2 induced MT-like protein in bone marrow.

Animals↗
PubMed1994

The effect of sodium salicylate on the osteoclast-like cell formation and bone resorption in a mouse bone marrow culture.

Salicylates are reported to have an inhibitory effect on bone resorption in vivo and in vitro. The present study examined the effect of sodium salicylate on the formation of osteoclast-like cells in vitro. When mouse bone marrow cells were cultured for 8 days with 10(-8) M 1 alpha, 25-dihydroxyvitamin D3 (1 alpha, 25(OH)2D3), numerous clusters of mononuclear and multinucleated cells (MNCs) formed, which stained positive for tartrate-resistant acid phosphatase (TRAP-positive). In similar cultures using sodium salicylate, the number of both TRAP-positive mononuclear and TRAP-positive MNCs were found to diminish in proportion to the concentration of sodium salicylate. A time-course experimental model showed that the number of TRAP-positive MNCs decreased slightly when sodium salicylate was given early in the culture period, and decreased markedly when the drugs were given later in the culture period. Pit formation and bone-resorption area on the bone slices were also inhibited by adding sodium salicylate continuously with 1 alpha, 25(OH)2D3. The sodium salicylate showed no cytotoxic effect because the total number of adherent cells, including both TRAP-positive and TRAP-negative cells, was independent of the presence of sodium salicylate. These results suggest that sodium salicylate has an inhibitory effect on the recruitment of osteoclast-like MNCs and that this inhibition is greater during the later stage of mouse bone marrow culture.

Acid Phosphatase↗
PubMed1994

Effects of insulin on in vitro bone formation in fetal rat parietal bone.

We examined the effects of insulin on bone formation including the mineralizing process. Twenty-day fetal rat parietal bones were cultured for 96 h on grids in a serum-free medium. For the precise assessment of bone formation, histomorphometry, with an image analyzing system, was used to measure the areas of mineralized bone and bone matrix, and the numbers of osteoblasts and osteoclasts. In order to confirm the effects of insulin on bone mineralization, the calcium content of the bone and the release of previously incorporated 45Ca into the medium were measured. Insulin, at a concentration of 10(-6) M or higher, increased the areas of mineralized bone and bone matrix, and the number of osteoblasts. Osteoclasts were seldom observed in bones on day 0 or in bones treated with insulin. In bones treated with insulin at a concentration of 10(-6) M, the calcium content of bone increased. At an insulin concentration of 10(-7) M or higher, the dry weight of decalcified bone increased. Lactate production in the medium increased dose-dependently. The inhibited release of 45Ca in bones indicated that insulin acts by increasing calcium retention. We demonstrated that insulin has an effect on bone-forming and bone-resorbing cells to enhance the bone forming process from matrix formation to mineralization.

Animals↗
PubMed1993

The effects of colchicine or vinblastine on the blood calcium level in rats.

In order to clarify how microtubule inhibitors induce hypocalcemia, rats were injected with intravenous colchicine (1 mg/kg) or vinblastine (2 mg/kg). The blood calcium levels decreased rapidly, and the minimum values, reached 4 h after the injection, were 7.55 +/- 0.70 mg/100 ml (mean +/- S.D., P < 0.001) for colchicine and 7.61 +/- 0.17 mg/100 ml (P < 0.001) for vinblastine. At 24 h, these values returned to the normal range (10.13 +/- 0.42 mg/100 ml). The blood calcium values in rats fed a low calcium diet and in thyroparathyroidectomized rats were also reduced by colchicine. The incorporation of blood 45Ca into bone was reduced by the injection of colchicine. Histologically, the bone cells of rats injected with either drug were severely damaged 8 h after the injection. These results indicate that hypocalcemia may be mediated by interference with the regulatory mechanisms of bone cell calcium homeostasis, and that the destruction of microtubules may be closely related to the development of the hypocalcemia.

Animals↗
PubMed1993

Unstable DNA in a patient with a severe form of congenital myotonic dystrophy.

Recently, an unstable DNA (expanded CTG repeat) was identified as the mutation that causes myotonic dystrophy (DM). By Southern blot analysis of DNA derived from peripheral blood, patients with congenital form of DM are shown to have greater expansion of DM specific band than is seen in the analyses of adult form of DM. We present here tissue expression of unstable DNA in an autopsied case of severe congenital form of DM. Our study revealed the largest expanding band of 19 kb was uniformly seen in various tissues from an autopsied infant with congenital form of DM.

Adult↗
PubMed1993

Inhibitory effects of fucoxanthin, a natural carotenoid, on N-ethyl-N'-nitro-N-nitrosoguanidine-induced mouse duodenal carcinogenesis.

Fucoxanthin was shown to inhibit chemical carcinogenesis. Fucoxanthin is a natural carotenoid prepared from brown algae which is an ingredient used daily in Japanese food. In this study, all mice were given 0.01% N-ethyl-N'-nitro-N-nitrosoguanidine in their drinking water for 4 weeks. This was followed by 0.005% fucoxanthin in dimethylsulfoxide or the vehicle alone in the drinking water. In the 16-week fucoxanthin-treated group both the percentage of tumor-bearing mice and the average number of tumors per mouse were significantly lower than those of the control group. The results indicate that fucoxanthin inhibited duodenal carcinogenesis induced by N-ethyl-N'-nitro-N-nitrosoguanidine in mice.

Animals↗
PubMed1993

Osteopontin mRNA expression during bone resorption: an in situ hybridization study of induced ectopic bone in the rat.

To study the relationship between the expression of osteopontin mRNA and ectopic bone formation and resorption, in situ hybridization using 35S-labeled RNA probes was performed on ectopic bone that was induced in an experimental rat model. The expression of type I collagen and osteocalcin in this ectopic bone was also examined. After 6-week-old male Wistar rats were injected intravenously with colchicine at a dose of 1 mg/kg, trabecular bone-like ectopic calcified tissue had formed in the medial bone marrow cavity of the tibia on day 4, and then continued to increase progressing forward to the distal cavity. On day 8 peak growth was attained, after which it was resorbed within 4 days as a result of osteoclast recruitment. Subsequent in situ hybridization of sections of the ectopic bone at 4, 6, 8, and 10 days after this colchicine treatment revealed that high levels of the type I collagen mRNA were expressed in the osteoblasts of the mineralized ectopic bone surface, not only during the formation period but also during bone resorption. Although osteocalcin showed no specific signals throughout the experiments, osteopontin mRNA was expressed temporarily at day 10 during the initial phases of ectopic bone resorption, primarily in both osteoblasts and osteocytes and further in some osteoclasts. These results suggest that de novo synthesis of osteopontin is closely associated with bone resorption and could possibly be required to initiate and mediate this biological process.

Animals↗
PubMed1993

Asymptomatic Becker muscular dystrophy: histological changes in biopsied muscles.

The histological changes observed in consecutive tests of biopsied muscles from an asymptomatic patient with Becker muscular dystrophy (BMD) are reported. The first biopsy showed active muscle necrosis and clustered regenerating fibers. The second biopsy revealed chronic myopathic changes mixed with neurogenic involvement. It is stressed that active myogenic changes observed in younger and asymptomatic BMD patients were followed by chronic myogenic or neurogenic change with age. Finally, we confirm the necessity of checking for dystrophin of abnormal size or reduced abundance by immunoblot analysis.

Adolescent↗
PubMed1993

[Effects of microtubule inhibitors on the amelogenesis in rat incisor enamel at the maturation stage: changes of staining patterns of GBHA on the enamel surface].

We investigated the effect of microtubule inhibitors on the amelogenesis in rat incisor enamel at the maturation stage by the glyoxal bis (2-hydroxyanil) (GBHA) staining method. Several red stripes stained with GBHA appeared on the maturation enamel surface of control rats. Colchicine injection (1.3 mg/kg, s.c.) disarranged the GBHA staining stripes and increased the staining area. The ratio of the GBHA staining area to the maturation enamel surface was about 25% in the control, but this value increased about 60% at 8 and 24 hr after the colchicine injection. Lumicolchicine, which does not have the ability to disrupt microtubules, did not cause any significant changes in the enamel surface. The incorporation of 45Ca to the maturation enamel was also reduced by colchicine. Since the hypocalcemic action of microtubule inhibitors may be related to the change of the enamel surface, other drugs, sodium salicylate and sodium fluoride, that have a hypocalcemic action were tested. The staining pattern was not altered by these drugs. Therefore, the hypocalcemic action was independent of the changes of the GBHA staining pattern. These results indicated that the disruption of microtubules in the ameloblasts inhibited calcium movement in the maturation enamel, resulting in the disarrangement of the GBHA staining pattern.

Amelogenesis↗
PubMed1993

[Observations of bone and incisor dentin of rabbits injected with rhodamine-labeled albumin by confocal laser scanning microscope].

The confocal laser scanning microscope (CLSM) is the most recently developed microscope using the confocal system and laser light source. This microscope is possible to create optical sectioning images from any depth of the specimen. In this study, the incorporation of rhodamine-labeled albumin (R-ALB) into the bone and incisor dentin was observed by CLSM. Male Japanese white rabbits were given an intravenous injection of R-ALB every two days for 10 days and sacrificed 3 days after the last injection. Transverse ground section of the tibia about 80 microns thickness showed the incorporation of orange-red fluorescence labeling into the endosteal surface as well as the Haversian system of bone. Each labeling line of R-ALB was clearly visible by CLSM compared with the normal fluorescence image. Three-dimensional reconstruction of the sectioning images showed the process of the incorporation of R-ALB into the bone and the complexity of the labeled pattern. R-ALB was incorporated into the incisor dentin and showed the periodic labeling pattern. The high resolution image of the periodic labeling pattern was observed by CLSM. These results indicated that CLSM is a valuable apparatus for studying the fluorescence labeling images of hard tissues.

Albumins↗
PubMed1993

[Fluorescent labelling of rhodamine-labelled albumin in rabbit incisor dentine].

Incorporation of rhodamine-labelled serum albumin (R-ALB) into the developing dentine was investigated by fluorescent microscopy. Male Japanese white rabbits were injected with R-ALB at a dose of 50 mg/kg and the undecalcified section of the incisor dentine was obtained 11 days after the injection. The orange-red fluorescent labelling of R-ALB was observed in the internal dentine. The labelling consisted of several periodic stripes and decreased its intensity toward the predentine-dentine junction. Serum concentration of R-ALB rapidly decreased after the injection and 10% of the initial value was present after 12 hours. The concentration gradually decreased thereafter. No relationship was observed between the fluorescent labelling pattern and the change in the concentration of serum R-ALB. These results suggest that R-ALB fluorescent labelling is related to the diurnal dentine formation by the odontoblasts in the rabbit incisor.

Animals↗
PubMed1993

[Ultrastructure of immotile spermatozoa obtained from infertile male patients].

We sometimes experienced infertile patients whose sperms had no motility but were not stained by Eosin Y. In this paper we report five cases of so-called "immotile spermatozoa". The ultrastructure of sperm tails was examined by transmission electrone microscope (TEM). These cases were selected from the out-patient population who attended infertility clinic of our department. The semen analyses showed that all the cases had sperm motility below 1% and more than 90% of the spermatozoa were proven alive. Family history revealed that one case had an infertile sibling. None of them had situs inversus, bronchiectasis and chronic sinusitis which are classic trias of Kartagener's syndrome. They had no symptoms of upper respiratory tract infection which was caused by the abnormality in the flagella of the respiratory tract. The TEM pictures of sperm tails showed partial deletion of inner dynein arms in two cases, lack of central microtubular doublets (so-called 9 + 0) in two cases and disarrangement of microtubular doublets in one case. For the treatment of these cases there is no effective means but AID. However, the rapid progress of IVF-ET techniques and a report that the spermatozoa from Kartagener's syndrome had showed penetration into eggs encouraged us to think the micromanipulation of spermatozoa with IVF-ET as a hopeful option of the treatment in the near future.

Adult↗