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Biomedical subjects

K Takegoshi

Publications and source records attributed to K Takegoshi.

At least 19 recordsLinked to original sources
PubMed1999

Narrowband excitation of (2)H powder pattern and its application to (2)H 1D exchange sample-turning NMR.

Frequency-selective narrowband excitation of the (2)H powder pattern was examined. Selection of a single spectral band with a linewidth of ca. 15 kHz was achieved by a narrowband (1)H --> (2)H cross polarization by using the time-averaged precession frequency method. Further narrowing with a ca. 5 kHz linewidth is achieved by DANTE irradiation. The narrowband excitation was applied to transform a recently developed 2D spin-exchange method for obtaining structural information (Chem. Phys. Lett. 260, 159, (1996)) into its 1D analogue. The determination of the D-C-D bond angle was demonstrated for alpha-glycine-[2,2-d(2)]. Further, the intermolecular polarization transfer between two deuterons separated by 0.299 nm was detected with the mixing time of 500 ms.

Deuterium↗
PubMed1999

13C-1H dipolar recoupling under very fast magic-angle spinning using virtual pulses.

A new solid-state NMR pulse sequence for recoupling 13C-1H dipolar interactions under magic-angle spinning is proposed, which works under a spinning speed of a few to several tens kilohertz. The sequence is composed of two different frequency switched Lee-Goldburg sequences, and the modulation of the spin part of the 13C-1H dipolar interaction is introduced by a virtual pulse sequence consisting of unitary operators connecting the rotating frame and the tilted rotating frame. When the cycle time of the spinning is equal to or twice the cycle time of the sequence, the 13C-1H dipolar interactions can be recoupled. The sequence is insensitive to experimental imperfections such as rf inhomogeneity or frequency offset, and the resulting lineshape can be represented by a simple analytical equation based on the zeroth-order average Hamiltonian. Experimental results for [2-(13)C] L-valine x HCl are reported.

Carbon Isotopes↗
PubMed1998

Solid-state photodimerization of 9-methylanthracene as studied by solid-state 13C NMR.

The locus of the photodimerization reaction of 9-methylanthracene in the crystal was examined by high-resolution solid-state 13C NMR techniques. Examination of the 13C spectra of the products showed that only the trans dimer is formed by the solid state photodimerization, while both trans and cis dimers are formed by the photodimerization in benzene solution. The 1H T1 relaxation curves for the monomer and the dimer at various exposure times were separately observed via well-resolved 13C peaks. The two T1 curves exhibit characteristic features for relaxation of a weakly coupled two-spin system. By analyzing the T1 curves, the spin diffusion rates between the monomer and the dimer and the fraction of the dimer were obtained for various exposure times. From the result, the maximum domain size of the minor component during the photodimerization process was estimated to be ca. 0.3 microm. The heterogeneous domain structure generated by the photodimerization indicates that the reaction takes place at defects of the crystal in the monomer.

Anthracenes↗
PubMed1998

Effects of branched-chain amino acid-enriched nutrient mixture on natural killer cell activity in viral cirrhosis.

A controlled study was performed in 18 viral cirrhosis patients to evaluate whether immune function, as indicated by natural killer (NK) cell activity, was improved by a branched-chain amino acid-enriched nutrient mixture (nutrient-mixture), Aminoleban EN. Five patients received the nutrient-mixture (100 g/day) for 2 to 6 weeks preceded by control periods. Five additional patients received the nutrient-mixture for 2 to 4 weeks, and the remaining 8 patients did not receive the nutrient-mixture. NK cell activity, CD16, CD8, CD11b, and amino acids were assayed before and after the administration of the drug in the nutrient-mixture-supplemented group, and two times with 1 to 6 month intervals in the control group. In the nutrient-mixture-supplemented group (n = 10), increasing NK cell activity, expressed as the ratio of values of post-treatment to that of baseline (ratio > 1.25) was detected in 7 (70%) patients, whereas in the control group (n = 13), it was detected in only 1 (7.7%) (p < 0.01). While in the affected group (NK cell activity ratio > 1.25, n = 7), all patients had compensated liver cirrhosis, in the unaffected group (NK cell activity ratio < 1.25, n = 3), 2 of 3 patients had decompensated liver cirrhosis (p < 0.02). Laboratory data, indicating severity of liver cirrhosis, such as total bilirubin and albumin, showed better values (p < 0.01, p < 0.05 respectively), and baseline NK cell activity was low (8.7 +/- 7.2% vs 33.3 +/- 13.0%, p < 0.05) in the affected group than unaffected group. NK cell subpopulations such as CD16 (%), CD11b (%) and one of the populations of T cell such as CD8 (%) showed no significant change throughout the study. As for amino acids analysis, Fischer's ratio was increased in the nutrient-mixture-supplemented group compared to the control group (p < 0.05), but none of the amino acids showed significant change. Thus the changes in NK cell activity were not explained by increase in NK cell subpopulations nor changes of amino acids. These results suggest that the branched-chain amino acid-enriched nutrient mixture increases NK cell activity moderately in patients who have compensated liver cirrhosis and shows lower values of baseline NK cell activity.

Adult↗
PubMed1997

Selective homonuclear polarization transfer in the tilted rotating frame under magic angle spinning in solids.

An application of the R2TR method (1995, Chem. Phys. Lett. 232, 424) to selective homonuclear polarization transfer under magic angle spinning is proposed. It is shown that, for a spinning speed fast enough to remove the maximum homonuclear dipolar coupling constant omegaD involved, the flip-flop and flop-flop mechanisms are suitable for recoupling the spins with a chemical shift difference larger than omegaD and a difference comparable to or smaller than omegaD, respectively. It is also shown that, for fast polarization transfer, the off-resonance frequencies should be much higher than the RF intensity in the flip-flop condition, while for the flop-flop condition, the off-resonance frequencies should be much lower than the RF intensity. Some one- and two-dimensional experiments are proposed by utilizing the capability of the R2TR method to abruptly switch on and off the recoupling condition, and are demonstrated for triply 13C-enriched l-alanine. The mixing time required for population transfer was found to be ca. 0.5 ms for the methine and methyl 13C spins separated by 1.5 A and ca. 5 ms for the methyl and the carboxyl carbons separated by 2.5 A. The experimental results and theoretical simulations show that selective polarization transfer is achieved when the difference in the isotropic chemical shifts between the relevant pair of spins and a neighboring spin is more than 1000 Hz.

Alanine↗
PubMed1993

Non-specific immunological abnormalities and association of autoimmune diseases in idiopathic portal hypertension. A study by questionnaire.

A large survey by questionnaire of idiopathic portal hypertension (IPH) in Japan disclosed that 11.9% of 160 cases were associated with one or two autoimmune diseases, and 26.3% of them disclosed hypergammaglobulinemia. Patients with IPH also frequently showed one or more autoantibodies in the serum, such as antinuclear or anti-smooth muscle antibodies. These findings overlapped frequently in the same patient. These data imply that immunological disturbance and/or chronic antigenic stimulation are related to the pathogenesis of IPH, though the exact immunological mechanisms remain unclear. It will be necessary to study more specific immunological reactions in IPH.

Autoantibodies↗
PubMed1991

Human T-lymphotropic virus type 1-associated myelopathy and primary sclerosing cholangitis.

We report the first case of human T-lymphotropic type 1-associated myelopathy (HAM) linked with primary sclerosing cholangitis (PSC). The patient, a 44-year-old woman, also suffered from ulcerative colitis and polyarthritis. Two years and nine months after the clinical onset of PSC, the coexistence of HAM was shown by neurological manifestations characterized by slowly progressive symmetrical myelopathy, predominantly involving pyramidal tracts, and positive antibodies to human T-lymphotropic virus type 1 in serum as well as in cerebrospinal fluid.

Adult↗
PubMed1989

Drug-induced mononucleosis-like hepatic injury in a patient with systemic lupus erythematosus.

A case of systemic lupus erythematosus (SLE) with mononucleosis-like hepatic injury was described. An emergent cesarean section was performed in a 25 yr-old house wife at 34 weeks gestation, followed by administration of several antibiotics. After the surgery she complained of high fever, hepatomegaly and dull right hypochondralgia, and mild liver dysfunction was also found. The liver biopsy showed prominent mononuclear cell infiltration in the sinusoids with minimum hepatocellular necrosis and mild triaditis, resembling hepatic lesion in infectious mononucleosis (mononucleosis-like injury). There were no clinical and serological features suggestive of infectious mononucleosis. This hepatic lesion was thought to be a manifestation of allergic reaction to drugs to which the lymphocyte stimulation test was found to be positive. Immunological abnormalities inherent in SLE might be related to occurrence of such allergic drug reaction.

Adult↗
PubMed1989

[The clinical usefulness of portal venous flow ratio by hepatic angiography with 99mTc-Sn colloid in chronic liver diseases: a comparison with histological finding].

The ratio of portal venous to hepatic blood flow was measured in chronic liver diseases by radionuclide angiography with 99mTc-Sn colloid and its clinical value was discussed. The ratio was proportionally decreased to the progression of the diseases (normal 74.5 +/- 7.3%, chronic hepatitis 58.8 +/- 9.2%, compensated liver cirrhosis 29.3 +/- 19.3%). In alcoholic liver diseases, the standard deviation of the ratio was large as 52.7 +/- 23.7%, and the low ratio in the early period of the disease increased within one or two months as the disease recovered. In comparison with the histological findings of the liver, the ratio in the alcoholic liver diseases was well correlated with the severity of liver fibrosis and liver cell swelling. In conclusion, this noninvasive and simple method is valuable in diagnosing the chronic liver disease, especially alcoholic liver diseases, and also in estimating its clinical course.

Chronic Disease↗
PubMed1988

Light and electron microscopic study of the liver in paraquat poisoning.

Intrahepatic cholestasis in paraquat poisoning in man has been thought to be secondary to extensive bile duct injuries, though its exact mechanism remains unsettled. We have examined liver biopsy specimens from two cases of paraquat poisoning. Case 1 (fatal) presented severe intrahepatic jaundice, and liver biopsy showed centrilobular cholestasis with extensive bile duct loss. Ultrastructurally, dilatation of bile canaliculi with decrease of microvilli and thickening of pericanalicular ectoplasm was found in the hepatocytes. Case 2 (alive) showed mild liver dysfunction without jaundice. While liver biopsy showed nonspecific reactive changes with intact bile ducts and ductules, electron microscopy disclosed dilatation of bile canaliculi with decrease of microvilli and thickening of pericanalicular ectoplasm in the hepatocytes, suggesting that damage to the bile secretory apparatus in the hepatocytes develops irrespective of extensive bile duct loss. These findings suggest that bile secretory apparatus in the hepatocytes as well as biliary epithelial cells could be a target of paraquat or its metabolites.

Adult↗
PubMed1986

A case of Venoplant-induced hepatic injury.

The first case of hepatic injury induced by Venoplant, extracts of Aesculus Hippocastanum, having antiinflammatory activities, was described. A 37 yr-old man was admitted for treatment of pathological fracture of the left brachial bone. He had been received 65 mg Venoplant at another hospital several hours before admission. 17 days later, a liver function test showed mild abnormality and 60 days after injection, he complained of pruritus and jaundice. Laboratory studies revealed moderate elevation of total bilirubin, ALP, gamma-GTP and mild eosinophilia. CT studies and ERC showed no signs of extrahepatic obstructive jaundice. The lymphocyte stimulation test was positive. The liver biopsy demonstrated marked cholestasis with zonal necrosis in the centrilobular areas but showed little or no changes in the portal tracts. These features are consistent with drug-induced hepatic injury.

Adult↗