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Biomedical subjects

T Takano

Publications and source records attributed to T Takano.

At least 505 records · Page 28Linked to original sources
PubMed1989

[Influence of tannic acid on physical and chemical properties of alpha-tricalcium phosphate-citric acid-tannic acid complex].

A mixture of alpha-tricalcium phosphate [alpha-Ca3(PO4)2; alpha-TCP] with a citric acid solution produces a hardened alpha-TCP-citric acid complex. The influence of tannic acid as an additive in the solution on the physical and chemical properties of the obtained complex was examined as a basic study for new calcium phosphate materials incorporating alpha-TCP. alpha-TCP was mixed with mixing liquids containing citric and tannic acids at various ratios [total acid = 45% (w/w)] at a powder/liquid = 2.2/1.0 (g/g). Compressive strength, setting time, and solubility & disintegration of the resulting complexes were measured by the methods specified by ADAS No. 61. After immersing the plates of the complexes in distilled water for 1 and 7 days, the surface structure of the plates was examined by using X-ray diffraction, scanning electron microscopy and IR spectroscopy. The substances solubilized and disintegrated in the water for 1 day were also examined by measuring quantitative Ca and P concentration. When the ratio of tannic acid to total acids (T/A) was higher than 30% (w/w), both setting time and solubility & disintegration increased remarkably. In the case of the complex at T/A = 30%, both setting time and solubility & disintegration showed the minimum value (6.25 min and 1.70%). For compressive strength, the maximum value (139 MPa) was obtained at T/A = 10%. Although the strength decreased markedly with increasing T/A beyond 10%, that of the complex at T/A = 30% was still a high level (103 MPa). The products on the surfaces before and after immersing the plates in distilled water were also discussed.

Calcium Phosphates↗
PubMed1989

The effect on the cornea of alpha cyclodextrin vehicle for cyclosporin eye drops.

We tested four different combinations of alpha-CD and CYA: 0.075% and 80 mg/mL alpha-CD, 0.025% CYA and 40 mg/mL alpha-CD, 0.009% CYA and 20 mg/mL alpha-CD, and 0.003% CYA and 10 mg/mL alpha-CD. We found that 0.025% CYA (alpha-CD[40 mg/mL]) resulted in the least corneal toxicity and penetrated in the cornea 5 to 10 times more than did lipophilic vehicle with CYA.

Administration, Topical↗
PubMed1988

Purification by hydrophobic chromatography of soluble cytochrome b5 of human erythrocytes.

Soluble cytochrome b5 of human erythrocytes was purified very effectively by hydrophobic chromatography using a butyl-Toyopearl 650 column. Cytochrome b5 was adsorbed tightly on the column in the presence of 60% saturated ammonium sulfate, and was eluted at 40% saturation of ammonium sulfate in the elution buffer. The chromatography gave a good yield of cytochrome b5 of the highest purity so far reported as estimated from the 414 nm to 280 nm absorbance ratio of the oxidized form of the cytochrome b5. The value obtained with the cytochrome b5 purified in this study was 6.57, and is higher than the previously reported highest value of 6.4 (Hultquist, D.E., Dean, R.T. and Douglas, R.H. (1974) Biochem. Biophys. Res. Commun. 60, 28-34). Spectral properties including molecular absorption coefficients were determined using the cytochrome b5 purified by this method.

Amino Acids↗
PubMed1988

Monoclonal DLR1a/104G antibody recognizing peroxidized lipoproteins in atherosclerotic lesions.

Monoclonal DLR1a/104G antibody which recognizes peroxidized lipoproteins was raised. Mice were immunized with the float-up fraction of the atherosclerotic arterial homogenate from WHHL rabbits. Sensitized spleen cells were fused with myeloma cells (P3/U1). Hybridoma clones were selected using peroxidized LDL prepared by CuSO4-catalyzed peroxidation and native LDL as positive and negative standards, respectively. The monoclonal DLR1a/104G antibody was highly reactive with peroxidized LDL, slightly with LDL modified with malondialdehyde, but not significantly with acetyl- or native LDL. The antigenicity in the case of peroxidized LDL did not decrease on extraction with hexane/isopropanol (3:2). The antigenicity coincided with the fluorescence (E350, F430) of the protein fraction of LDL peroxidized with CuSO4. These results suggest that an antigenic determinant exists in atherosclerotic lesions which is the same as that for lipoproteins peroxidized with CuSO4.

Animals↗
PubMed1988

Nucleotide sequence of the maltohexaose-producing amylase gene from an alkalophilic Bacillus sp. #707 and structural similarity to liquefying type alpha-amylases.

The nucleotide sequence of the gene for maltohexaose-producing amylase from an alkalophilic Bacillus sp. #707 was determined. Starting at an ATG initiation codon, an open reading frame was composed of 1554 bp (518 amino acids). The NH2-terminal portion encoded a 33 amino acid-long signal peptide. The deduced amino acid sequence of the extracellular mature enzyme was more than 60% homologous to those of the liquefying type alpha-amylases but not to those of the saccharifying type alpha-amylases. The sequence of its signal peptide was completely different from those of other alpha-amylases.

Amino Acid Sequence↗
PubMed1988

Selected ion monitoring analysis of NB-818, a new calcium entry blocker in a series of dihydropyridines, in human plasma.

NB-818 is expected in clinical use to produce an antihypertensive effect and simultaneously to promote an increase in cerebral blood flow, owing to its vasodilator activity. To determine NB-818 levels in human plasma for pharmacokinetic studies, a capillary column gas chromatography/mass spectrometry/selected ion monitoring (GC/MS/SIM) method was employed. Because NB-818 was degraded under GC conditions, stable derivatives had to be prepared for GC/MS measurements. Reaction of NB-818 with silylation agents produced derivatives quantitatively. In the silylation, however, the carbomoyl group of NB-818 was replaced by silyl moieties. NB-818 is possibly metabolized at the carbamate moiety alone, giving a compound with a hydroxymethyl group in place of the carbamoyloxymethyl group. Since this compound and NB-818 gave the same derivative, efforts were devoted to separating them. A detection limit below 0.1 ng ml-1 was attained. The calibration curve was linear in the concentration range 0.1-10 ng ml-1 (r = 0.9998), and the coefficient of variation was 5.5% and 3.1% at concentrations of 1 and 10 ng ml-1, respectively.

Calcium Channel Blockers↗
PubMed1988

The effect of hyperbaric oxygen on cerebral hemoglobin oxygenation and dissociation rate of carboxyhemoglobin in anesthetized rats: spectroscopic approach.

By measuring near-infrared transmittance spectra, we examined the effect of HBO on cerebral Hb oxygenation in normal and ischemic brain in the anesthetized rat. The oxygenation state of Hb was around 80% in the rat brain under 1 ATA air breathing. HBO did not induce further cerebral Hb oxygenation above 2 ATA in control animals but improved tissue oxygenation in the ischemic brains. The oxidation-reduction state of cyt. aa3 in the normal brain was not affected by HBO. In the ischemic brain, however, HBO prevented ischemia-induced reduction of cyt. aa3. Non-invasive optical monitoring of COHb with visible reflectance spectrophotometry was also examined. HBO markedly accelerated dissociation of COHb. Tight correlation was found between the optical signal and COHb content determined from blood samples. These results demonstrated the usefulness of optical monitoring in vivo under hyperbaric conditions.

Anaerobiosis↗
PubMed1988

Hydrocortisone stimulation of proliferation and glycosaminoglycan synthesis in rabbit craniofacial chondrocytes in vitro.

Hydrocortisone stimulated glycosaminoglycan (GAG) synthesis, a cartilage phenotype, in chondrocytes from mandibular condylar cartilage (MCC), nasal septal cartilage (NSC) and sphenooccipital synchondrosis (SOS). These stimulations were dose- and time-dependent, being maximal 27 h after addition of 10(-7) M hydrocortisone. The maximal induced increase of GAG synthesis was about 100%, 50% and 20% that of non-stimulated MCC, SOS and NSC chondrocytes, respectively. When stained with toluidine blue, all three types of cortisone-treated chondrocytes showed stronger metachromasia than non-treated controls. DNA synthesis was also increased by hydrocortisone, reaching a maximum 20 h after the addition; stimulation was also dose-dependent and maximal at a concentration of 10(-6) M. The maximal increase in DNA synthesis was 200% in NSC chondrocytes, 90% in SOS chondrocytes, and slight in MCC chondrocytes. However, there was no stimulation of DNA synthesis in serum-free medium, in contrast to that of GAG synthesis. These observations suggest that hydrocortisone regulates craniofacial growth by controlling the differentiation of these chondrocytes directly and their proliferation indirectly, and that the difference in their responses to hydrocortisone may reflect different responses in vivo.

Animals↗
PubMed1988

Interaction of nitrite with catalase in the perfused rat liver.

The interaction of nitrite with catalase was investigated spectrophotometrically in the perfused rat liver. Real-time spectral changes were obtained using a reflectance scanning spectrophotometer in the liver perfused with a haemoglobin-free medium in a non-recirculating system. Administration of sodium nitrite caused a specific pattern of spectral change indicating the decomposition of catalase compound I to free catalase. The spectral change due to the interaction with nitrite did not occur during potassium cyanide or ethanol infusion, nor in the aminotriazole-pretreated rat liver. The spectral change was observed at concentrations of nitrite in the perfusate over 0.01 mM, and the K0.5 value (the concentration producing half the maximum spectral change) was 0.06 mM. It was concluded that relatively low concentrations of nitrite caused decomposition of catalase compound I in the physiologically functioning liver cell.

Animals↗
PubMed1988

Metabolism of chloral hydrate in the anoxic perfused liver.

The metabolism of chloral hydrate (CH) under anoxic conditions was investigated in the non-recirculating, hemoglobin-free liver perfusion system. CH uptake in the anoxic liver decreased to about 80% of that in the oxygen-supplied liver. The reduction of CH to trichloroethanol (TCE) increased and the oxidation of CH to trichloroacetic acid (TCA) decreased. The TCE/TCA ratio increased; however, the total trichloro compounds, that is TCE and TCA, were not significantly altered by anoxia. Though approximate 14% of the CH infused into the oxygen-supplied liver was changed to substances other than TCE or TCA, the unknown part was a very small portion in the anoxic liver. The decrease in CH uptake, by the anoxic liver, is thought to be equivalent to the decrease of the unknown metabolites. The TCE/TCA ratio under anoxia was also altered by pyruvate or lactate infusion.

Animals↗
PubMed1988

Metabolism of dichloromethane and the subsequent binding of its product, carbon monoxide, to cytochrome P-450 in perfused rat liver.

The interaction of cytochrome P-450 and dichloromethane (DCM) was investigated spectrophotometrically in the perfused rat liver. DCM bound to cytochrome P-450 and showed a type I spectral change, with a peak at 450 nm. The peak at 450 nm was developed by addition of exogenous carbon monoxide (CO) to the perfusate. By examining the pattern of the spectral change, we concluded that CO formed during DCM metabolism by cytochrome P-450 bound to cytochrome P-450 in the perfused liver.

Animals↗
PubMed1988

Generalized eruption with severe liver dysfunction associated with occupational exposure to trichloroethylene.

Generalized dermatitis due to trichloroethylene is rare. A 21-year-old printer developed exfoliative dermatitis with mucous membrane involvement, fever and liver dysfunction after a 2-week occupational exposure to trichloroethylene. Positive patch-test reactions to trichloroethylene and to one of its metabolites, trichloroethanol, were observed. This dermatitis is considered to be mediated by a delayed-type hypersensitivity mechanism.

Adult↗
PubMed1988

Mapping of human lactate dehydrogenase-A, -B, and -C genes and their related sequences: the gene for LDHC is located with that for LDHA on chromosome 11.

Human testis-specific lactate dehydrogenase-C (LDHC) gene-related sequences are located with the LDHA gene on chromosome 11. The LDHB gene is on chromosome 12. Chromosomes 1, 2, 4, 9, and 10 appear to contain LDHA gene-related sequences, whereas the X chromosome and chromosome 13 possess LDHB gene-related sequences.

Blotting, Southern↗
PubMed1988

Vascular response to carbon dioxide in areas with and without diaschisis in patients with small, deep hemispheric infarction.

The reactivity of cerebral blood vessels to changes in PaCO2 in areas of the cerebral cortex with or without diaschisis was investigated in 13 patients in a subacute or chronic stage after a small capsular infarct. A focal area of hypoperfusion (area of diaschisis) was detected in the ipsilateral sensorimotor cortex in each patient. Hyperventilation caused a significant reduction of regional cerebral blood flow in the area without diaschisis and only a tendency for regional cerebral blood flow to decrease in the area with diaschisis; CO2 inhalation induced a slight increase in regional cerebral blood flow in the area without diaschisis and a significant increase in regional cerebral blood flow in the area with diaschisis. Regional cerebral blood flow reactivity to hypocapnia was significantly less in the area with diaschisis than in the area without, whereas the hypercapnic response was more marked in the area with diaschisis than in the area without. Our results suggest that in the area with diaschisis, the arterioles may be abnormally vasoconstricted at rest such that they cannot constrict further in response to hypocapnia but can dilate more during hypercapnia than in the area without diaschisis. This excessive resting vasoconstriction may result from decreased tissue elaboration of CO2 due to local decrease of metabolic function.

Adult↗