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Biomedical subjects

T Hirasawa

Publications and source records attributed to T Hirasawa.

At least 37 records · Page 2Linked to original sources
PubMed1999

The advantage of alfacalcidol over vitamin D in the treatment of osteoporosis.

Although alfacalcidol is widely used in the treatment of osteoporosis, its mechanism of action in bone is not fully understood. Alfacalcidol stimulates intestinal calcium (Ca) absorption, increases urinary Ca excretion and serum Ca levels, and suppresses parathyroid hormone (PTH) secretion. It remains to be clarified, especially under vitamin D-replete conditions, whether alfacalcidol exerts skeletal effects solely via these Ca-related effects, whether the resultant suppression of PTH is a prerequisite for the skeletal actions of alfacalcidol, and, by inference, whether alfacalcidol has an advantage over vitamin D in the treatment of osteoporosis. To address these issues, we (1) compared the effects of alfacalcidol p.o. (0.025-0.1 microg/kg BW) vis-à-vis vitamin D(3) (50-400 microg/kg BW) on bone loss in 8-month-old, ovariectomized (OVX) rats as a function of their Ca-related effects, and (2) examined whether the skeletal effects of alfacalcidol occur independently of suppression of PTH, using parathyroidectomized (PTX) rats continuously infused with hPTH(1-34). The results indicate that (1) in OVX rats, alfacalcidol increases BMD and bone strength more effectively than vitamin D(3) at given urinary and serum Ca levels: larger doses of vitamin D(3) are required to produce a similar BMD-increasing effect, in the face of hypercalcemia and compromised bone quality; (2) at doses that maintain serum Ca below 10 mg/dl, alfacalcidol suppresses urinary deoxypyridinoline excretion more effectively than vitamin D(3); and (3) alfacalcidol is capable of increasing bone mass in PTX rats with continuous infusion of PTH, and therefore acts independently of PTH levels. It is suggested that alfacalcidol exerts bone-protective effects independently of its Ca-related effects, and is in this respect superior to vitamin D(3), and that the skeletal actions of alfacalcidol take place, at least in part, independently of suppression of PTH. Together, these results provide a rationale for the clinical utility of alfacalcidol and its advantage over vitamin D(3) in the treatment of osteoporosis.

Animals↗
PubMed1999

Agravitropic mutant for the study of hydrotropism in seedling roots.

Roots have been shown to respond to a moisture gradient by positive hydrotropism. Agravitropic mutant plants are useful for the study of the hydrotropism in roots because on Earth hydrotropism is obviously altered by the gravity response in the roots of normally gravitropic plants. The roots are able to sense water potential gradient as small as 0.5 MPa mm(-1). The root cap includes the sensing apparatus that causes a differential growth at the elongation region of roots. A gradient in apoplastic calcium and calcium influx through plasmamembrane in the root cap is somehow involved in the signal transduction mechanism in hydrotropism, which may cause a differential change in cell wall extensibility at the elongation region. We have isolated an endoxy loglucan transferase (EXGT) gene that is strongly expressed in pea roots and appears to be involved in the differential growth in hydrotropically responding roots. Thus, it is now possible to study hydrotropism in roots by comparing with or separate from gravitropism. These results also imply that microgravity conditions in space are useful for the study of hydrotropism and its interaction with gravitropism.

Calcium Channels↗
PubMed1999

Endoxyloglucan transferase cDNA isolated from pea roots and its fluctuating expression in hydrotropically responding roots.

We isolated an endoxyloglucan transferase cDNA (Ps-EXGT1) from the roots of an agravitropic pea mutant, ageotropum. The putative product of the cDNA was 34.1 kDa and consisted of 293 amino acid residues. The predicted amino acid sequence was 75.1-88.6% identical to those of EXGT genes in other plants. The Ps-EXGT1 cDNA was strongly expressed in elongating roots and stems but not in either mature stems or young leaves. In roots, the transcription level of Ps-EXGT1 was most abundant in the rapidly growing region. When root elongation was inhibited by a water stress, Ps-EXGT1 transcription was repressed. The roots curved hydrotropically due to differential growth of the cortical cells in the elongation zone when the root cap was exposed to a gradient of water potential; the length of the cells on the side of lower water potential was much longer than those on the side of higher water potential. The expression pattern of Ps-EXGT1 in the hydrotropically responding roots fluctuated between the side of the higher water potential and that of the lower water potential in the elongation zone. In other words, the accumulation of Ps-EXGT1 mRNA was much greater on the side of lower water potential than on that of higher potential just prior to the commencement of positive hydrotropism. When the roots started to curve slightly away from the side of higher water potential causing a rhythmic oscillatory movement [Takano et al. (1995) Planta 197: 410], there was more transcription of Ps-EXGT1 on the side of higher water potential. These results suggest that the transcription of Ps-EXGT1 is involved in cell growth and that this regulation of transcription plays a role in the differential growth of hydrotropically responding roots.

Amino Acid Sequence↗
PubMed1999

fcsA29 mutation is an allele of polA gene of Escherichia coli.

The cold-sensitive fcsA29 mutation of Escherichia coli was found to be a new type of cold-sensitive allele of the polA gene encoding DNA polymerase I, caused by an Asp(116)-->Asn change in the 5'-->3' exonuclease domain. The fcsA29 mutant showed typical polA mutant phenotypes such as UV sensitivity and unacceptability of recA mutation. Cold-sensitive growth of the mutant was suppressed by introduction of a sulA mutation, indicating that cell filamentation was due to the SOS response.

Alleles↗
PubMed1999

Evaluation of the amount of residual monomer on UDMA-based resins by FTIR.

The purpose of this study was to establish a method using FTIR to evaluate the polymerization characteristics of UDMA-based resins. Three kinds of experimental UDMA-based resins were prepared with various molar fractions. IR spectra of the cured film specimens were measured with FTIR before and after extracting residual monomer from each specimen by MeOH. From the IR spectra, the changes in the number of double bonds were measured, with the NH absorbance peak as an internal standard, and the amounts of residual monomers (RM) were calculated. The MeOH-immersed specimens were analyzed by HPLC. The RM measured by FTIR were compared with those measured by HPLC. The RM measured by HPLC were more than those by FTIR. Since these differences could be due to the difference in the area measured, this FTIR estimation method of residual monomers in cured resins using the NH absorbance peak as an internal standard could be an appropriate method when the resin monomer does not contain aromatic compounds.

Carbon↗
PubMed1999

Experimental impression tray fabricated with a NiTi shape memory alloy plate.

A small experimental impression tray was fabricated with a NiTi shape memory alloy plate. After recovery of the shape memory effect, the upper rims of the tray holding the impression were opened to some extent, the resistance during removal of the model from the impression was significantly decreased compared to a commercially available tray and the tray before recovery of the shape memory effect. The pull-out force of the model from the impression was 23.5(0.2)N for the commercially available tray, 23.5(3.9)N for the experimental tray before recovery of the shape memory effect and 14.7(4.0)N after recovery of the shape memory effect (heated for 15 min at 70 degrees C). Therefore the tray should be useful in teeth fracture free modeling.

Dental Alloys↗
PubMed1999

[A sudden death case in the bath with peculiar scald].

A 60-year-old man was found dead in the bathtub of his house on the 2nd of February. Erythema with a clear border was observed on the right side of the face, trunk and around the knees, though the left side of the face, the hips and the feet were normal. The water heater was set outside of the bath, and the heated water flowed from the heater to the bath through the upper pipe. In order to determine the mechanism of the peculiar scalding, changes in the water temperature in the bathtub were measured under the same conditions. An hour after turning on the water heater, the surface water temperature of the bath was 73 degrees C. Zonal gradation of the temperature was observed. At the level of the opening for the lower intake pipe, it was 50 degrees C. The border of the scalding was consistent with the water layer above 50 degrees C.

Baths↗
PubMed1998

Activation of dihydropyridine sensitive Ca2+ channels in rat hippocampal neurons in culture by parathyroid hormone.

We examined the effects of parathyroid hormone (PTH) on rat hippocampal neurons in culture to determine whether it caused a similar intracellular calcium concentration ([Ca2+]i) increase in these cells to that seen with renal epithelial cells and found that PTH induced the effect in about 30% of the neurons. The effects appeared gradually during continuous administration of full-length PTH(1-84) or its active fragment, PTH(1-34), but not of an inactive fragment, PTH(39-84). However, the active fragment of the PTH-related peptide (PTHrP(1-34)) had little effect on [Ca2+]i during 60 min of administration. The PTH effect was inhibited by nifedipine, an L-type Ca2+ channel antagonist, and facilitated by S-(-)-BAY K 8644, an L-type Ca2+ channel agonist. Our findings suggest that PTH is one of the causal factors for the age-related increase in the density of voltage gated Ca2+ channels in hippocampal neurons.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1998

Actions of zinc on rapidly inactivating A-type and non-inactivating M-type potassium currents in bullfrog sympathetic neurons.

The actions of zinc on A-type potassium current (I(A)) were studied in dissociated bullfrog sympathetic neurons. Zinc (1-300 microM) caused a parallel shift in the activation and inactivation curves to a depolarizing direction, thereby enhancing I(A) around physiological resting potential. An EC50 value was 70-100 microM for these actions. The zinc actions were non-selective in a sense that zinc inhibited M-type potassium current (I(M)) with an IC50 value of 300 microM. Zinc was without effect on the maximum conductance for I(A) and the kinetic behavior for I(M). The ability of low concentrations of zinc to modulate separate set of potassium currents such as I(A) and I(M) in conceptually distinct manner may therefore assume pathophysiological importance for autonomic neurons.

Animals↗
PubMed1998

Serous borderline ovarian tumor with functioning stroma in a postmenopausal woman: immunohistochemical analysis of steroidogenic pathway.

An epithelial ovarian tumor with estrogenic manifestations (vaginal bleeding, vaginal softening) was encountered in a 70-year-old woman. The preoperative serum levels of estrone, estradiol, and testosterone were elevated. A right ovarian serous papillary tumor of borderline malignancy was removed and found to have a cellular, focally luteinized stroma. Steroidogenic enzymes, including 3beta-hydroxysteroid dehydrogenase and P450 cytochromes specific for cholesterol side-chain cleavage (P450scc), 17alpha-hydroxylation (P45017alpha), and aromatization (P450arom), were immunohistochemically demonstrated in the stromal cells. Immunohistochemical evaluation of these enzymes suggest significant functional differences among the enzymatically-activated stromal cells. That only rare stromal cells were immunoreactive for P450arom suggests that most of the testosterone synthesized in the tumor is extragonadally converted to estrogen, resulting in tumor-associated estrinism.

3-Hydroxysteroid Dehydrogenases↗
PubMed1998

A pilot study on modified endoscopic variceal ligation using endoscopic ultrasonography with color Doppler function.

OBJECTIVE: The purpose of the study was to evaluate feasibility of modified endoscopic variceal ligation (EVL), namely the "intensive ligation" method, using endoscopic ultrasonography with color Doppler function (EUS-CD). METHODS: Forty-five patients with esophageal varices were treated by modified EVL. Variceal hemodynamics in 38 patients were examined using EUS-CD, which showed abdominal hemodynamics in detail under physiological conditions before and after the modified procedure. RESULTS: 1) The median number of treatment sessions was 3.2, and 41 O-rings on average were required per individual patient. 2) The median nonrecurrence period after treatment was 18 months (Kaplan-Meier method). 3) Nine patients with a good response to modified EVL did not have recurrences for 16.9+/-2.8 months, and five with a poor response had recurrences at 5.8+/-2.2 months. Gastric varices were related to the response to modified EVL (p < 0.05, Mann-Whitney's U test). 4) Minor complications in modified EVL as well as standard EVL were experienced; however, we had a patient with the development of meningitis, which was a major septic complication. 5) Before modified EVL, EUS-CD demonstrated that good responders had undeveloped (grade I) gastric varices in five of nine (56%); however, poor responders had developed (grade III) gastric varices in four of five (80%) (p < 0.05, Mann-Whitney's U test]. 6) After modified EVL, EUS-CD revealed that six of nine (67%) good responders and one of five (20%) poor responders showed a decrease in color signals in supplying veins; however, none of the former (0%) and three of the latter (60%) showed an increase (p < 0.05, Mann-Whitney's U test]. CONCLUSION: Modified EVL was safe and effective, at least with regard to intermediate-term outcome, especially when treating patients with undeveloped gastric varices revealed by EUS-CD. Both good and poor responders showed no exacerbation of gastric varices after the modified procedure, ultrasonographically as well as endoscopically.

Adult↗
PubMed1998

Genetic typing of the mouse and rat nude mutations by PCR and restriction enzyme analysis.

A genetic typing method for the mouse and rat nude mutations by PCR and restriction fragment length polymorphism (RFLP) analysis was developed. Since restriction sites useful for RFLP analysis do not exist in the mouse nu and rat rnu mutations, artificial restriction sites were introduced by PCR with modified primers. Three genotypes in the mouse (nu/nu, nu/+ and +/+) or rat (rnu/rnu, rnu/+ and +/+) are rapidly differentiated with the PCR-RFLP assay. In addition, congenic nude strains can be efficiently established by using this assay. Finally, genetic mapping of the rnu locus was performed with microsatellite markers. The locus order on rat chromosome 10 was D10Mgh14-(2.0cM)-D10Mit2-(1.4cM)-rnu-(0.7cM++ +)-D10Mgh6-(2.7cM)-D10Mit8.

Animals↗
PubMed1998

Physical properties of resin-modified glass-ionomers.

The physical properties and shear bond strength of two resin-modified glass-ionomers: RMGIs (FJL and VT) and as a control, a conventional glass-ionomer: CGI (FJ), were evaluated. Ninety percent of the setting shrinkage under dry conditions and nominal hygroscopic expansion in water during 360 h occurred within the first 24 h. The nominal hygroscopic expansion of CGI was 0.38% while the RMGIs demonstrated over 1%, but considering the setting shrinkage the total hygroscopic expansion of CGI and the RMGIs were over 7 times and about 2.5 times, respectively. The thermal expansion of the RMGIs after water immersion was greater than that under dry condition. In contrast, FJ demonstrated expansion less than under dry condition. There was no significant difference between FJL and VT (P < 0.05) as regard water absorption. The shear bond strength of the RMGIs to enamel and dentin were superior to FJ, except for VT to dentin.

Absorption↗
PubMed1997

Excessive formation of basement membrane substance in clear-cell carcinoma of the ovary: diagnostic value of the "raspberry body" in ascites cytology.

Formation of basement membrane-like substance or so-called collagen core was characteristic of clear-cell carcinoma of the ovary in ascites cytology. The hyaline extracellular material was stained light green in Papanicolaou smears and pinkish to purplish red in Giemsa preparations and was frequently observed within the cancer cell clusters in all ten samples of clear-cell carcinoma. Such a structure termed "raspberry body" was focally seen in one of 30 specimens of serous cystadenocarcinoma and one of 30 samples containing reactive mesothelial cells. The "raspberry body" was not found in ascitic fluid from ten patients with mucinous cystadenocarcinoma and two with endometrioid carcinoma. Overproduction of the acidic-charged basement membrane substance was confirmed by 1) cytochemical positivity for periodic acid-Schiff, alcian blue (pH 2.5 or pH 1.0), colloidal iron, and periodic acid-methenamine silver, 2) immunocytochemical demonstration of laminin and type 4 collagen, and 3) ultrastructural identification of excessive formation of the basal lamina. Recognition of the "raspberry body" helps cytopathologists make a cytologic diagnosis of this chemotherapy-resistant malignancy disseminated in ascitic fluid.

Adenocarcinoma, Clear Cell↗
PubMed1997

Genetic typing of the mouse ob mutation by PCR and restriction enzyme analysis.

A genetic typing method for the mouse obese (ob) mutation by PCR and restriction fragment length polymorphism (RFLP) analysis was developed. Three genotypes (ob/ob, ob/+ and +/+) of the ob mouse are rapidly differentiated with this assay. Since only a small biopsy specimen (tail end) is necessary for the genotyping, the ob mouse at any age is typable and can be used in subsequent breeding or research. Obese homozygotes (ob/ob) were efficiently produced by mating heterozygotes (ob/+) only, which were selected by using the PCR-RFLP assay.

Animals↗
PubMed1996

Detection and genomic analysis of canine parvovirus by the polymerase chain reaction.

Prevalence of canine parvovirus type 2 (CPV-2) in Japanese dogs and genomic variations among the virus strains were examined. Two-step polymerase chain reaction with double-nested primer pairs designed in the NS and VP1/VP2 genes of CPV-2 was developed for the detection of the viral genome in faecal samples. A total of 74 samples obtained from diarrhoeal house dogs between 1993 and 1995 were tested by the PCR. The virus-positive rate was 54.1%, showing that CPV-2 is still involved in many cases of acute infectious diarrhoea in Japanese dogs. The VP1/VP2 gene of the positive samples was subjected to restriction fragment length polymorphism (RFLP) analysis and nucleotide sequencing. RFLP patterns of the samples were almost identical to those of one CPV-2 strain (TDKet-91-42) isolated in 1991, but different from those of the CPV-2 in the late 1970s and 1980s. The results suggest that a new genotype of CPV-2 appeared and spread among Japanese dogs in the early 1990s.

Animals↗