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Biomedical subjects

F Takahashi

Publications and source records attributed to F Takahashi.

At least 19 recordsLinked to original sources
PubMed1995

Modulation of the plasma cholesteryl ester transfer by stachybotramide.

Plasma cholesteryl ester transfer protein (CETP), which mediates the transfer and exchange of neutral lipids (cholesteryl esters (CE) and triglycerides (TG) and phospholipids between plasma lipoproteins, plays an essential role in reverse cholesterol transport system. We have found that a fungal metabolite, stachybotramide, modulates the activity of CETP. Stachybotramide stimulated the [14C]CE transfer from high density lipoprotein (HDL) to very low density lipoprotein (VLDL) and low density lipoprotein (LDL) by 1.3- to 1.5-fold at 0.2-0.5 mM. This stimulation was abolished in the presence of anti-CETP antibody. On the other hand, the transfer of [14C]CE from LDL and VLDL to HDL was slightly reduced by stachybotramide at 0.5 mM. Unlike the transfer of [14C]CE, the transfer of [3H]TG from HDL was not significantly affected by stachybotramide. These results suggest that stachybotramide preferentially stimulate the CETP-mediated transfer of CE from HDL to both VLDL and LDL.

Antibodies, Monoclonal↗
PubMed1995

Theoretical analysis of image defocus with intraocular lens decentration.

We used a theoretical eye model to evaluate the effect on peripheral images when planoconvex, biconvex, and meniscus intraocular lenses (IOLs) decenter 1 mm or 2 mm upward or downward from the pupillary center. A light source was projected from an angle of 0, 20, 28, or 40 degrees downward to a retina with a radius of curvature of 11 mm. When the IOL was centered, the light focused at a single point on the retina. When the IOL was decentered, the light became more dispersed as the incident angle of the light increased. The most dispersion was noted with the meniscus IOL; the least with the biconvex IOL. Astigmatism and aberration, which IOL decentration increases, were thought to cause the image defocus. These results suggest that IOL decentration may affect the sharpness of peripheral images.

Accommodation, Ocular↗
PubMed1995

Bone marrow neutrophilia and suppressed bone turnover in human interleukin-6 transgenic mice. A cellular relationship among hematopoietic cells, osteoblasts, and osteoclasts mediated by stromal cells in bone marrow.

To elucidate the effect of interleukin-6 (IL-6) on bone and bone marrow (BM), human IL-6 transgenic mice (hIL-6 tgm) were produced. Their bone and BM were examined histologically, radiologically, histomorphometrically, and hematologically on a temporal basis. hIL-6 tgm showed histologically evident neutrophilia in BM. Increase in precursors of granulocytes and monocytes in hIL-6 tgm was demonstrated by an assay for colony forming unit in culture (CFU-C) of BM cells. Decrease in osteoblasts and osteoid and suppression of primary spongiosa formation were predominantly observed in hIL-6 tgm at 14 weeks old, the terminal stage of life for hIL-6 tgm. An assay for colony forming unit in fibroblastic (CFU-F) of BM cells revealed a decrease in osteoblast precursor (with regard to alkaline phosphatase-positive colonies) in hIL-6 tgm at 15 weeks old. Histomorphometry demonstrated a decrease of both osteoclast number and bone resorption in hIL-6 tgm. These results suggested that enhanced granulocytic hematopoiesis, suppressed bone turnover, and alteration of cellular population in stromal cells in BM occurred in hIL-6 tgm. Thus we provide new findings that facilitate understanding of cellular interrelationships among hematopoietic cells, osteoblasts, and osteoclasts mediated by stromal cells in BM.

Animals↗
PubMed1995

Activation of ornithine decarboxylase in epithelial cells of rat intestine.

Intestinal ornithine decarboxylase (ODC) is strongly induced by dietary amino acid and protein feeding. However, the consequence of this induction is unknown. In this study, we analyzed the relationship between intestinal ODC activity and DNA synthesis in villus and crypt cells of rat intestine. Single amino acid diets and protein diets stimulated ODC activity in villus cells, but not in crypt cells. However a 20% casein diet induced ODC activity and increased the putrescine concentration in villus and crypt cells. Administration of alpha-difluoromethylornithine, a suicide inhibitor of ODC, prevented both an increase in putrescine level and DNA synthesis in the crypt cells. Observations suggested that the induction of ODC is necessary to initiate DNA synthesis in rat intestinal epithelium.

Animals↗
PubMed1994

Postoperative results of vascularized double fibula grafts for femoral pseudoarthrosis with large bony defect.

In open femoral bone fractures osteomyelitis may develop as a complication. Many difficulties are experienced in the treatment of those fractures because an extended bone defect may be formed after repeated operations, and then amputation of the femoral bone becomes necessary. Since 1981 the present authors have performed the vascularized double fibula grafts in the treatment of 18 patients with successful results. With this grafting method, both vascularized double fibula grafts are collected at the same time, one as an intramedullary graft and the other as an onlay graft. The most important point in carrying out grafting by this method is to prepare the recipient bone bed adequately. In many cases, it is necessary to carry out the primary operation to curette the focus, and resect necrotic tissues and sequestrated bone before the vascularized double fibula grafts, and then grafting is performed as a second operation after infection has been controlled following the initial operation. Although differences in time required for recovery cannot be eliminated completely, it becomes possible for 16 out of 18 patients to walk without the use of a brace and crutches within 13 months on average.

Adolescent↗
PubMed1994

[A case of unilateral brain-stem tumor and impaired ventilatory response].

A 44-year-old man with a unilateral brain-stem tumor (ganglioglioma) presented with marked hypoventilation and irregular breathing. His respiratory muscle strength was impaired slightly, and his ventilatory responses to chemical stimuli were markedly diminished. Magnetic resonance imaging of the brainstem revealed that the tumor was located in the left superior cerebellar peduncle and the medulla, and involved the left lateral portion of the medullary reticular formation, ambiguous nucleus, and solitary nuclear complex. From these findings, we conclude that the abnormality of ventilatory control may have been caused by damage to both the unilateral respiratory neuron group in the medulla and the afferent pathway to the respiratory motor unit on the opposite side.

Adult↗
PubMed1994

[Basic evaluation of the new fully automated urine sediment analyzer (U-FCM) based on flowcytometric technology].

We developed a new automated urine sediment analyzer (U-FCM) based on Flow Cytometry with the cooperative technical aid of TOA Medical Electronics Co., ltd. Flow Cytometry using an argon laser (wave length 488 nm) is used as the method for detection. This instrument provides quick, easy and accurate screening for patients whose urinalysis abnormalities indicate the need for further testing. Abnormal patient samples are separated from patient samples whose parameters are totally normal, thus decreasing the need for additional testing. The instrument is useful as a diagnostic aid, and in monitoring the therapeutic effect. Also it is useful in the health checking service for visitors at the AMHTS office.

Autoanalysis↗
PubMed1993

Structure and expression of hedgehog, a Drosophila segment-polarity gene required for cell-cell communication.

The complete nucleotide sequence of the coding region of hedgehog (hh), a segment-polarity gene in Drosophila melanogaster, was determined. The gene was found to include three exons which would encode a 421- (or 471-) amino acid (aa) polypeptide with a long hydrophobic stretch. The hh mRNA was about 2.3 kb long and expressed throughout development. The hh expression in an embryo occurred in stripes, while that in imaginal discs occurred in the posterior compartment. As a whole, the spatial expression pattern of hh mRNA was very similar to that of engrailed (en), a homeobox gene required for the formation of the anterior-posterior compartment boundary. Unlike en, no hh expression was observed in the central nervous system.

Animals↗
PubMed1993

Inhibition of glucose absorption by phlorizin affects intestinal functions in rats.

BACKGROUND: To investigate the mechanism of regulation of intestinal disaccharidase activity and glucose absorption, the effect of dietary intake of phlorizin, a potent and specific inhibitor of intestinal glucose transport, on intestinal disaccharidase activity and Na(+)-dependent glucose transporter was examined in rats. METHODS: Jejunal disaccharidase activity and the number of Na(+)-dependent glucose transporters were determined in rats maintained on a low-starch diet, a high-starch diet, or low-starch diets containing various amounts of phlorizin (0.1%-0.9% wt/wt). RESULTS: Jejunal disaccharidase activity increased in a dose- and time-dependent manner. Stimulation of jejunal disaccharidase activity only occurred when phlorizin was added to starch-containing diets, not when it was added to a carbohydrate-free diet. Addition of the same amount of phloretin and glucose (constituents of phlorizin), to the diet failed to increase disaccharidase activity. The maximum binding of phlorizin to brush border membrane vesicles was increased in the rats fed phlorizin, whereas the dissociation constant remained unchanged, suggesting an increase of glucose transporter expression. CONCLUSIONS: Dietary phlorizin increased the jejunal disaccharidase activity and Na(+)-dependent glucose transporter expression. The trigger for these changes may have been due to an increased luminal glucose content.

Administration, Oral↗
PubMed1992

Diffuse nerve fiber layer loss in normal tension glaucoma.

14 eyes of 14 normal tension glaucoma (NTG) patients with the maximum intraocular pressure (IOP) > or = 19 mmHg and 16 eyes of 16 NTG patients with the maximum IOP < 19 mmHg were examined. All patients had a scotoma confined to the upper or lower hemifield. Eyes with the maximum IOP > or = 19 mmHg showed significantly diffuse retinal nerve fiber layer (RNFL) loss in the RNFL area corresponded to the spared visual hemifield as compared to those with the maximum IOP < 19 mmHg. The results suggests that, even in NTG, IOP may be an important factor causing optic nerve damage.

Female↗
PubMed1992

[Pharmacokinetic studies of menogaril (TUT-7) with rats].

Menogaril (TUT-7) is a novel antitumor antibiotic belonging to anthracyclines. The pharmacokinetic parameters derived from plasma concentration-time profiles after repeated (for 14 days) or single oral administration of TUT-7 to rats were found to be not significantly different by either administration schedule. The rats with artificial liver dysfunction were obtained by subcutaneous application of carbon tetrachloride (CCl4, 1 ml/kg) for 3 days. After oral administration of TUT-7 to the rats with CCl4-induced liver toxicity (3 daily administrations of 1mg/kg, S.C.), the maximum plasma concentrations (Cmax) and AUC of both the unchanged drug and its metabolite N-Demethyl menogaril, were increased. Also over all elimination was slower in animals with liver dysfunction.

Administration, Oral↗
PubMed1989

Experimental replantation of canine forelimbs after 78.5 hours of anoxia.

To assess the effect of ischemia on osteocyte survival and longitudinal growth in bone, one forelimb of eight puppies and seven dogs was amputated, perfused with iced Collins solution, maintained at 4 degrees C for 72 hours (78.5 hours total anoxia), and replanted. Five puppies were kept for 1 year to assess bone growth. Undergoing bone labeling on days 1, 8, and 15, the other animals were sacrificed at 22 days to assess osteocyte survival. Osteocytes survived replantation in all dogs and one puppy; most osteocytes died in two puppies. In five long-term puppies, central epiphyseal growth was disturbed, but the peripheral portions maintained nearly normal growth, with almost normal bone length being achieved at 1 year.

Animals↗
PubMed1988

Effect of alpha-methyl-p-tyrosine and an antiserum to rat growth hormone (GH)-releasing factor (GRF) on plasma GH secretory profile during a continuous infusion of human GRF in rats.

The effects of alpha-methyl-p-tyrosine (alpha-MT) and an antiserum specific to rat growth hormone-releasing factor (GRF) on growth hormone (GH) secretory profile during a 6-h continuous infusion of human GRF(1-44) NH2 were observed in unrestrained adult male Wistar rats. All rats were provided with two indwelling cannulae; one in the right atrium for undisturbed blood collection and the other in the inferior vena cava for 0.9% NaCl or GRF infusion. GRF was administered by an infusion pump at a dose of 50 ng/kg b.wt./min ma GH levels during baseline period were low with little fluctuation. GH secretion was augmented significantly during continuous GRF infusion in control rats but interpeak intervals remained unaltered. When an antiserum specific to rat GRF was administered, episodic GH secretion was abolished. In these rats, pulsatile GH secretion indistinguishable from that of control rats was observed in the continuous presence of human GRF. Although alpha-MT inhibited episodic GH secretion, alpha-MT-treated rats exhibited high-frequency, low-amplitude episodic GH secretion and elevated baseline levels during the stimulation. There were no differences in the amount of GH secreted during GRF infusion between rats that had received either alpha-MT or antiserum to rat GRF. Since GH secretion to GRF is determined largely by somatostatin, the results suggest that phasic release of somatostatin plays an important role in determining the rhythmicity of episodic GH secretion, and that it is modulated by alpha-MT but not by the immunoneutralization of GRF.

Animals↗
PubMed1988

Effect of testosterone on growth hormone secretion in female rats during a continuous infusion of growth hormone releasing factor.

The effect of testosterone on growth hormone (GH) secretory pattern during a 6-hour continuous infusion of human GH-releasing factor (GRF) (1-44) NH2 was observed in unrestrained adult female Wistar rats. Rats had been ovariectomized or sham operated 6 weeks previously. Three weeks after the ovariectomy, the rats received sesame oil or testosterone propionate at a dose of 1 or 2 mg s.c. daily for 21 days. All rats were provided with two indwelling cannulae: one in the right atrium for undisturbed blood collection and the other in the inferior vena cava for vehicle or GRF infusion. Vehicle or GRF was administered by an infusion pump at a dose of 50 ng/kg/min for 6 h. Serial blood specimens were obtained every 20 min. Sham-operated adult female Wistar rats exhibited a high-frequency, low-amplitude pulsatile GH secretion during a 6-hour vehicle infusion. When they received a 6-hour continuous infusion of GRF, the amplitudes of GH pulses and baseline GH values were markedly augmented, but the pulse frequency remained unaltered. The GH secretory pattern during a 6-hour vehicle infusion among ovariectomized rats was similar to that of sham-operated female rats, whereas the magnitude of elevation of GH pulse and baseline level in ovariectomized rats were significantly lower than in sham-operated rats. The ovariectomized female rats that had received 2 mg testosterone for 21 days showed a low-frequency, regularly timed, high-amplitude pulsatile GH secretion, and GH values during the intervening period were low. This GH secretory pattern was indistinguishable from that in adult male rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗