Biomedical subjects

R Tsukuda

Publications and source records attributed to R Tsukuda.

30 records · Page 2Linked to original sources

PubMed1993

In vivo stimulation of endosteal bone formation by basic fibroblast growth factor in rats.

Intravenous administration of human basic fibroblast growth factor (bFGF) for 2 weeks stimulated osteoblast proliferation and new bone formation in various skeletal bones in young and aged rats at dosage levels of 0.1 mg/kg/day and greater. Morphometry of the soft X-ray radiograms of cross sections of the tibia indicated about a 20% increase in the calcified bone area of the diaphysis at 0.1 mg/kg/day. The Ca and hydroxyproline contents showed statistically significant increases at this dosage. The new bone formation was found only on the endosteal side, and no periosteal bone formation was found. Similar systemic osteogenic potential was seen after intravenous administration of other growth factors of the FGF family, human acidic FGF and human heparin-binding secretory transforming protein-1. The above results suggest a potential therapeutic role for these growth factors in bone-loss diseases such as osteoporosis.

Aging↗

PubMed1992

Increase of basic fibroblast growth factor immunoreactivity and its mRNA level in rat brain following transient forebrain ischemia.

We examined the time course of basic fibroblast growth factor (bFGF) immunoreactivity and its mRNA level mainly in the hippocampus after transient forebrain ischemia using immunohistochemistry, enzyme immunoassay (EIA), Western blot analysis and in situ hybridization. Neuronal death in the hippocampal CA1 subfield was observed 72 h after 20 min of ischemia. The number of bFGF-immunoreactive(IR) cells increased 48 h-5 days after ischemia in all hippocampal regions. At 10 and 30 days, the bFGF-IR cells in the CA1 subfield had further increased in numbers and altered their morphology, enlarging and turning into typical reactive astrocytes with the advancing neuronal death in that area. In contrast, the number of bFGF-IR cells in other hippocampal regions had decreased 30 days after ischemia. The EIA study showed a drastic increase in bFGF levels in the hippocampus 48 h after ischemia (150% of that in normal rat) which was followed by further increases. In Western blot analysis, three immunoreactive bands whose molecular weights correspond to 18, 22 and 24 kDa were observed in normal rat and ischemia increased all their immunoreactivities. In the in situ hybridization study of the hippocampus, bFGF mRNA positive cells were observed in the CA1 subfield in which many bFGF-IR cells existed after ischemia. These data demonstrate that transient forebrain ischemia leads to an early and strong induction of bFGF synthesis in astrocytes, suggesting that the role of bFGF is related to the function of the reactive astrocytes which appear following brain injury.

Animals↗

PubMed1992

Stimulatory effect of ipriflavone on formation of bone-like tissue in rat bone marrow stromal cell culture.

The effects of ipriflavone (IP) (10(-5) M) on bone formation were studied in stromal cells from the femoral bone marrow of young adult rats cultured for 21 days in the presence of beta-glycerophosphate and dexamethasone. Stereoscopic microscopy showed nodule formation after 14 days of culturing, and both the number and the size of the nodules increased with time. The alizarin-red-stained calcified area in the nodules in the IP group was nearly 4 times as large as that in the control after 21 days. Light and electron microscopy revealed the presence of many osteoblast-like cells with developed rough endoplasmic reticulum and Golgi apparatus in the nodules in the control group after 14 days, and a collagenous fibril network was seen among the cells. After 21 days, calcification of the dense collagenous fibril network and bone matrix-like tissue were observed in many nodules, resulting in the formation of bone-like tissue containing osteocyte-like cells. In the IP group, the collagenous fibril network area in the nodules was greater than that in the control after 14 days, and a further increase in both the dense collagenous fibril network area and calcified bone-like tissue area was observed after 21 days. These findings indicate that IP stimulates bone-like tissue formation in the rat bone marrow stromal cell culture, suggesting that the promotion of collagen production by osteoblasts is involved in the stimulation of bone-like tissue formation by IP.

Animals↗

PubMed1992

Biochemical analysis of the bone of SHC rats with spontaneous hypercholesterolemia and renal dysfunction.

Spontaneously hypercholesterolemic (SHC) rats exhibit severe abnormalities in renal function and bone metabolism at old ages, in addition to hypercholesterolemia. SHC rats were also found to show endocrine abnormalities such as hyperthyroidism from young ages. In this study, biochemical and microdensitometric analyses were carried out using femurs to characterize further the abnormality in bone metabolism: whether biochemical markers of the bone may be affected by these abnormalities. At 6 weeks of age, the ashed weight and calcium content of the dried femurs were slightly lower in SHC rats than in age-matched Sprague-Dawley (SD) rats. None of the markers of microdensitometric analysis was changed. At 24 weeks of age, the ashed weight of dried femurs and the density of the marrow region of femurs were lower in the SHC rats. The results indicate that SHC rats exhibit severe abnormality in bone metabolism leading to biochemical changes in the bone at old ages whereas changes in bone markers were minimal at young ages before the onset of severe renal dysfunction.

Animals↗

PubMed1991

Increase in basic fibroblast growth factor-like immunoreactivity in rat brain after forebrain ischemia.

Using immunohistochemical techniques, a study was conducted to determine whether basic fibroblast growth factor (bFGF) is generated as one of the 'self-repair' responses in rat brain following transient forebrain ischemia. In normal brain, slight bFGF-like immunoreactivity was observed. However, in rats exposed to 20 min of forebrain ischemia, intense bFGF-like immunoreactivity was observed in the CA1 subfield of the hippocampus and the caudate putamen, and marked activity was evident in the temporal cortex, corpus callosum and the CA4 subfield of the hippocampus. Marked neuronal degeneration was also observed in these brain regions following forebrain ischemia. These results suggest that induction of bFGF-like immunoreactivity may be related to the healing which follows brain ischemia.

Animals↗

PubMed1989

Histomorphometric study of the parathyroid glands of the spontaneously hypercholesterolemic (SHC) rats with chronic renal failure.

Light and electron microscopic morphometry was performed on the parathyroid (PT) glands of the SHC rats with naturally occurring chronic renal failure. Macroscopically, the PT glands were distinctively hypertrophied in 24-week-old male SHC rats when compared with the corresponding controls, Sprague Dawley (SD) rats. Light microscopic morphometry on consecutive sections of the PT glands showed that the volume was about 3 times greater in the SHC rats, whereas there was no difference in the size of the chief cells. Mitoses were often found in the PT glands of the SHC rats. The total number of mitoses was about 8.5 times greater in the SHC rats, and was closely related to the volume of the PT glands. Ultrastructural morphometry of the chief cells revealed an increase in the cell surface area by the interdigitation of the plasma membrane and increases in the volume of mitochondria and Golgi complex. Secretory granules sometimes existed close to the cell surface in the SHC rats, but not in the SD rats. These results suggest that the PT glands of the SHC rats are hyperplastic mainly because of the proliferation of the chief cells. Concurrently, an increase in volume of the cell organelles suggests enhanced secretion activity in the chief cells.

Animals↗

PubMed1988

Suppressive effect of ipriflavone on bone depletion in the experimental diabetic rat: dose response of ipriflavone.

The dose dependent effect of ipriflavone (7-isopropoxy-isoflavone) on the femoral bone in streptozotocin-induced diabetic rats was studied by microdensitometric analysis. Diabetic rats showed severe hyperglycemia, glucosuria, hypoinsulinemia, associated with increased urinary calcium and hydroxyproline. Microdensitometric analysis revealed decreases in femoral length, bone width, and bone density. The dietary administration of ipriflavone (about 270 mg/kg/day) to the diabetic rats for 6 weeks prevented reduction of the cortical thickness index in the diaphysis and depletion of bone density in the distal metaphysis, and also reduced the inner diameter of the diaphysis; diabetic state was not improved. A simple correlation and linear regression analysis revealed that ipriflavone also significantly reduced the inner diameter in the diaphysis at a dose of 90 mg/kg/day, but not at one of 25 mg/kg/day. These results suggest that ipriflavone suppresses the depletion of the femoral bone through inhibition of bone resorption in a dose dependent fashion; its minimum effective dose is 90 mg/kg/day in experimental diabetes.

Animals↗

PubMed1987

Histopathologic observations on the senescence-accelerated mice (SAM) reared under specific pathogen free conditions.

Five to 12 months old senescence-accelerated mice reared under specific pathogen free conditions (SPF SAM) were subjected to histopathologic examination. Senescence-prone SAM-P/1/Ta, P/3/Ta, and P/8/Ta exhibited marked depletion in thymic cortical lymphocytes which were associated with lymph follicle formation in the medulla, and marked infiltration of lymphocytes in the submaxillary gland, kidney, and other peripheral tissues. Morphometrical analysis of the adrenal gland revealed cortical atrophy and medullary hyperplasia in male SAM-P/8/Ta at 5 months of age. Other characteristic changes were marked vacuolation of the renal proximal tubules in male P/3/Ta and P/8/Ta mice, and degeneration of vascular wall in the testis of P/3/Ta mice. The pathogenesis of these changes appeared to be related to the adrenal lesions. Systemic amyloid deposition, one of the characteristic features of SAM housed in conventional facilities was not observed under the SPF condition. Acceleration of senescence in SPF SAM may arise from disorders of the thymus and adrenal.

Adrenal Glands↗

PubMed1986

Effect of ipriflavone on glucocorticoid-induced osteoporosis in rats.

Ipriflavone, 7-isopropoxy-3-phenyl-4H-1-benzopyran-4-one, was administered orally for 12 weeks to male rats with prednisolone-induced osteoporosis. Microdensitometric analysis of a roentgenograph of the femurs revealed that ipriflavone increased the density of the distal metaphysis dose-dependently and tended to increase the density of the diaphysis. It also inhibited dose-dependently the decrease in the mechanical strength of the tibia, breaking strain and breaking energy, and the fractional content of ash in femurs. These results indicate that ipriflavone markedly suppresses bone resorption at the metaphysis where the content of trabecular bone with a rapid turnover rate is high, and possibly inhibits bone reduction at the diaphysis.

Animals↗

PubMed1986

[Effects of ipriflavone (TC-80, an anti-osteoporotic drug) on acute and chronic pain].

The effects of TC-80 on acute and chronic pain in rats and mice were examined. Single oral administration of TC-80 at 50-300 mg/kg was not analgesic in the phenylquinone writhing, acetic acid writhing, and hot plate tests in mice or the tail flick test in rats. Three-weeks administration of TC-80 in a dose of 100 mg/kg/day, p.o., to rats had no analgesic action in the acetic acid writhing and tail flick tests. When TC-80 was given orally in a dose of 100 mg/kg/day for 3 weeks to rats with adjuvant arthritic chronic pain, analgesic effects were observed 2 weeks after the start of administration in males and in ovariectomized estrone-supplemented females; the effect seen in the females was statistically significant. Changes in the bones of the hind paws were examined radiologically, and synovitis, periosteal new bone formation and bone destruction were examined histopathologically in the females. These variables were improved by treatment with TC-80 for 3 weeks. It is concluded that TC-80 has no analgesic effect, but may inhibit chronic pain by anti-osteoporotic action on bone disease.

Administration, Oral↗

PubMed1980

Immunopathology of rhino mouse, an autosomal recessive mutant with murine lupus-like disease.

Detection of high incidence of antinuclear antibodies (ANA) was reported in young homozygous rhino mice employing formalinized chicken erythrocyte nuclei as substrate for indirect immunoflourescence (IF) assay. The titers of ANA heightened with increasing age, and attained to 1:1024 by the time mice reached 5 months of age. The occurrence of ANA was associated with development of splenic and hepatic fibrosis, glomerulonephritis and abnormalities of lymphoreticular tissue. The granular deposits of IgG and C3 detected by direct IF were initially found at the basement membrane of dermal-epidermal junction of rhino mice aged 2.5 months. These deposits distributed progressively in the fibrotic areas of spleen and liver, and renal glomerular tufts at 5 months of age. Dense deposits revealed by electron microscopy were found in the regions where IF of IgG and C3 was observed. Acid buffer eluates from liver and kidney contained IgG reactive with nuclear antigens. Importance of homozygous rhino gene was discussed in relation to development of autoimmune disorders of these mice.

Animals↗

PubMed1977

Enhancement of tumor induction in rats with Moloney murine sarcoma virus by a "new" method based on direct injection into fetuses.

Undiluted, fivefold-diluted, and 25-fold-diluted doses of a stock of Moloney murine sarcoma virus were injected directly, in a volume of 0.025 ml, into the backs of fetal Sprague-Dawley rats by laparotomy through the uterine wall at 18 days of gestation. During the first 8 weeks after birth the young responded to the virus with remarkably high but dose-dependent incidences of neoplasms. When a one-fifth dilution of the virus preparation was inoculated at fetal ages 16, 18, and 20 days, the incidences of lesions decreased with advancing fetal age. The tumors developed preferentially at the virus inoculation site and/or in the proximal parts of the extremeties; all were considered to be of mesenchymal derivation, i.e., malignant mesenchymoma, rhabdomyosarcoma, osteosarcoma, fibrosarcoma or fibromyxosarcoma, hemangiosarcoma, plasmacytoma, and a giant cell tumor. This injection procedure provided us with a valuable experimental tool for the rapid screening or testing of potential chemical carcinogens and other biologic studies.

Animals↗