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Biomedical subjects

T Koga

Publications and source records attributed to T Koga.

At least 433 records · Page 24Linked to original sources
PubMed1991

Stimulation of the trunk area of the motor cortex elicits straining in dogs.

To clarify the cortical portion of dogs which corresponds to the portion to perform voluntary straining in human, the posterior sigmoid gyrus of anesthetized dogs was systematically stimulated. When reflex-straining was elicited at constant intervals (10-20 s) by stimulation of pelvic afferents, extra-straining (cortical straining) intervening between reflex-straining was elicited after a latent period (0.2-1.0 s) by pulse train stimulation of a focal portion in the trunk area of the motor cortex (M1). Cortical straining reset cycles of reflex-straining. The minimum threshold intensity was observed in the fifth or sixth layer of the focal portion. No difference was recognized between the firing patterns exhibited during cortical and reflex-straining by the phrenic and rectus abdominis muscle nerves, and by the nerves innervating the glottis adductors and external urethral sphincter. Pulse train stimulation of the focal portion, however, interrupted reflex-straining when it was applied during reflex-straining. Pulse train stimulation of the focal portion also elicited burst firings in the phrenic and abdominal muscle nerves after short latencies (20 and 12 ms). The short-latency bursts disappeared after severance of the medulla pyramis ipsilateral to the stimulated focal portion, but cortical straining induced by stimulation of the same cortical site persisted. Stimulation of the focal portion still elicited straining after severance of the ipsilateral hypothalamus, but not after severance of the cerebral peduncle at the midbrain level. However, the cortical stimulation intensified to about three times occasionally induced straining after severance of the peduncle. From these results, it may be concluded that stimulation of the focal portion in the trunk motor area induces straining through the cerebral peduncle, midbrain tegmentum, and pontine straining reflex center.

Abdominal Muscles↗
PubMed1991

An 82 year-old patient with sarcoidosis.

An 82 year-old woman presented with bilateral uveitis suggestive of ocular sarcoidosis, which led to a clouded vision. She was diagnosed as having sarcoidosis because of an elevated level of serum angiotensin converting enzyme (ACE), findings from a Ga67 scintiscan and the bilateral uveitis, although her chest X-ray film was normal. This patient is one of the most oldest patients on record to have sarcoidosis.

Age Factors↗
PubMed1991

[Effect of heat-staining procedure on the gram staining properties of mycobacteria].

Since the establishment of Gram stain by H.C.Y. Gram in 1884, it has been widely and routinely used as an aid for differentiation of bacteria. The bacteria are divided into three categories by the staining properties; Gram-positive, -negative, and -indefinite. All the text books in the world describe that mycobacteria such as M. tuberculosis are Gram-positive. By the merest chance, however, it was found that M. lepraemurium grown in tissues was not stained by the routinely used Gram staining method. Therefore, we tried to stain some of the mycobacteria by the Gram staining procedure which is widely used at present. The results obtained indicated that the mycobacteria tested were divided into three groups; the unstainable group such as M. leprae and M. lepraemurium, the Gram-positive and difficult-to-stain group which involves such slow growing mycobacteria as M. tuberculosis, M. avium, and M. intracellulare, and the Gram-indefinite group which contains such rapid growing mycobacteria as M. phlei, M. smegmatis, and M. chelonae. However, if Gram stain is carried out by the heating procedure at the first staining step, all the mycobacteria would become Gram-positive. Therefore, we emphasize that Gram staining of mycobacteria should be performed by the heating procedure.

Hot Temperature↗
PubMed1991

Purification and some properties of sucrose phosphorylase from Leuconostoc mesenteroides.

Sucrose phosphorylase (EC 2.4.1.7) was purified to homogeneity from Leuconostoc mesenteroides cells with a specific activity of 173.8 units per mg protein by ammonium sulfate fractionation, anion exchange HPLC on TSKgel DEAE-5PW, and hydrophobic HPLC on TSKgel Ether-5PW. The purified enzyme was an acidic protein having an isoelectric point of pH 4.6 and s0(20),W of 4.34S. The molecular weight of this enzyme was estimated to be 56,400 by sedimentation equilibrium, 55,000 by SDS-polyacrylamide gel electrophoresis, and HPLC gel filtration on TSKgel G3000SW, suggesting that the enzyme is a monomeric protein. With regard to molecular weight, amino acid composition, and N-terminal amino acid sequence of 30 residues, this enzyme is close to the glucosyltransferase A of Streptococcus mutans.

Amino Acid Sequence↗
PubMed1991

[5-year follow-up study of brain function in the healthy aged--study of the relationship between environmental factors and results of psychiatric examinations].

In order to investigate the relationship between environmental factors and results of psychiatric examinations, a questionnaire survey studying these factors and neurophysiological examinations (electroncephalography (EEG), somatosensory evoked response (SER) and contingent negative variation (CNV)), as well as clinical neuropsychiatric examinations and intelligence scale (Hasegawa's dementia rating scale (HDRS) and Kohs's blocking design test (KBDT)), were performed on 41 healthy aged (61-80 years old) who were participants in programs of Osaka Prefectural Center for the elderly. Initial examinations were conducted in 1983 and the second in 1988 on the same subjects for the purpose of measuring the aging process over 5 years with regard to brain function. A total of 29 subjects, for a participation rate of 82.9% (excluding deceased and those who moved away from the area), attended the second examination. The results are summarized as follows. 1. When environmental factors were compared for 1983 and 1988, a reduction in participation in social activity was observed in some of the aged in 1988, although differences in their daily living situations were unchanged. 2. The mean scores of HDRS and KBDT were 31.9, 98.6 in 1983 and 30.2, 94.6 in 1988 respectively, with only 2 subjects showing considerable decline of intelligence. 3. With regard to the neurophysiological examinations, the number of subjects with peak latencies of SER that were abnormally prolonged increased in 1988, while there was little difference in their EEGs between 1983 and 1988. 4. From these results, it appears that the relation between declines in brain function and environmental factors, involves multiple factors that will require further study.

Age Factors↗
PubMed1990

[Serum levels of beta-seminoprotein (beta-Sm) in patients with breast cancer].

Serum levels of beta-Sm (a component of human seminal plasma) were measured in patients with breast cancer or mastopathy by RIA method. 9.4 +/- 9.5 ng/ml in control healthy adult women and 11.7 +/- 15.7 ng/ml in 8 patients with mastopathy were observed. Whereas, in 30 patients with breast cancer including 28 pre-operation and 2 recurrence 64.5 +/- 52.3 ng/ml were observed. Especially, high levels of beta-Sm (135.8 and 182.3 ng/ml) in the recurrence were detected. Each case of 8 post-operation was below 50 ng/ml. Fifty-seven percent of patients with breast cancer including pre-operation and recurrence were showed over 50 ng/ml. In histological typing, the beta-Sm levels of papillotubular carcinoma were higher than that of scirrhous carcinoma. In tubular carcinoma, 45% of stage I, 67% of stage II and 100% of stage III, IV and recurrence cases were over 50 ng/ml. The evidence suggests that serum levels of beta-Sm is useful for the diagnosis of breast cancer.

Adenocarcinoma↗
PubMed1990

GM1 ganglioside reduces edema and monoaminergic neuronal changes following experimental focal ischemia in rat brain.

Seventy-two hours following a middle cerebral artery occlusion, the associated increase in water content on the ischemic side was significantly reduced by the exogenous administration of monosialoganglioside GM1 (30 mg/kg, i.p.). The levels of dopamine and serotonin on the ischemic side were approximately 50% and 80% of those on the contralateral non-ischemic side, respectively. Treatment with GM1 (5 times during the first 48 h after occlusion) produced a significant reduction in the levels of dopamine and serotonin loss. The present findings are compatible with the observed protective action of the exogenously administered GM1 following ischemic brain injury.

Animals↗
PubMed1990

Tissue-selective inhibition of cholesterol synthesis in vivo by pravastatin sodium, a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor.

Tissue selectivity of pravastatin sodium (pravastatin) in inhibition of cholesterol synthesis was investigated and its effect was compared with other 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors, such as lovastatin, simvastatin and ML-236B. Inhibition of cholesterol synthesis in vivo was measured by incorporation of radioactivity into the sterol fraction 1 h after intraperitoneal injection of [14C]acetate to mice. The drugs were orally administered to mice 2 h before the acetate injection. When pravastatin at a dose of 20 mg/kg was administered to mice, about 90% inhibition of cholesterol synthesis was observed in liver and ileum, but the inhibition was less than 14% in kidney, spleen, adrenal, testis, prostate and brain. This tissue selectivity of pravastatin was also demonstrated even in varying doses (5-100 mg/kg) and time (75-180 min) after drug administration. Other 3-hydroxyl-3-methylglutaryl coenzyme A reductase inhibitors did not show such a tissue-selective inhibition of sterol synthesis under the same conditions. These results obtained with the in vivo study were confirmed in vitro by the inhibition of sterol synthesis in various cultured cells and rats lenses, as well as by cellular uptake of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors.

Acetates↗
PubMed1990

Stereospecific recognition of inositol 1,4,5-trisphosphate analogs by the phosphatase, kinase, and binding proteins.

A series of DL-inositol 1,4,5-trisphosphate (IP3) analogs, with a bulky substitutent on the 2nd carbon of the inositol ring, has been synthesized. These compounds exert biological activities with only minor reduction in potency, in several assay systems (Hirata, M., Watanabe, Y., Ishimatsu, T., Ikebe, T., Kimura, Y., Yamaguchi, K., Ozaki, S., and Koga, T. (1989) J. Biol. Chem. 264, 20303-20308). Two analogs with aminocyclohexanecarbonyl (designated as analog 206) or aminobenzoyl group (analog 209) were separated into individual optical isomers and examined for stereospecificity in recognition by IP3-5-phosphatase, IP3-3-kinase and IP3 binding activity. IP3-5-phosphatase activity of erythrocyte ghosts was competitively inhibited by L-209 with a lower Ki value than D-IP3, but with a higher Ki value by L-206. D-Isomers of both analogs at 100 microM failed to inhibit the hydrolysis of D-[3H]IP3. On the other hand, D-isomers but not L-isomers of both analogs were as potent as D-IP3 in the recognition by IP3-3-kinase of rat brain cytosol and only the D-isomer of analog 206 could serve as substrate for the kinase. Also D-isomers of both analogs were equipotent to D-IP3 in displacing [3H]IP3 binding to rat cerebellum microsomes. These observations suggest that the IP3 analogs we synthesized are stereospecifically recognized by three IP3-recognizable proteins, but the phosphatase recognizes opposite isomers. Such being the case, the second hydroxyl group of D-IP3 may be involved in the recognition by IP3-5-phosphatase, but not by IP3-3-kinase and binding sites.

Animals↗
PubMed1990

[Aspects of parasternal lymphnode dissection in radical mastectomy for breast cancer].

In order to clarify the surgical aspects for parasternal lymphnode dissection to improve prognosis in patients with breast cancer, we have retrospectively investigated a total of 319 patients with breast cancer who underwent radical mastectomy with parasternal lymphnode dissection. During the 13 years from 1974 to 1986, 418 patients with breast cancer underwent radical mastectomy. Of these, 319 underwent combined dissection of the parasternal lymphnodes. Among these 319 cases, 36 (11.3%) showed pathologically-confirmed positive lymphnode metastasis. In those cases involving a tumor of diameter greater than 5 cm and more than 4 positive metastatic axillar lymphnodes, then the positive parasternal lymphnode metastasis was higher than 30%. The 5-year survival rate was 88.9% for negative parasternal lymphnode metastasis and 44.7% for positive cases (p less than 0.01 logrank test). The standard adjuvant chemotherapy, chemo-endocrine therapy and radiation therapy, each did not significantly affect or improve prognosis. We conclude that parasternal lymphnode positivity is an important factor in radical mastectomy affecting prognosis and a more powerful adjuvant chemotherapy must be developed to improve prognosis.

Breast Neoplasms↗
PubMed1990

Inositol 1,4,5-trisphosphate affinity chromatography.

Inositol 1,4,5-trisphosphate (IP3) affinity columns were made by coupling IP3 analogs to a supporting matrix. Sepharose 4B. IP3 5-phosphatase activity. IP3 3-kinase activity and IP3 binding activity from rat brain were absorbed on the IP3 columns. and were eluted by increasing KC1 concentration. This purification procedure increased the specific activities of these parameters 5-200-fold. Thus Sepharose 4B immobilized IP3 analogs can specifically interact with IP3-binding proteins, demonstrating that IP3 affinity columns are a good method for purifying such proteins. Furthermore, our results suggest that IP3 analogs can be linked to other molecules to make useful derivatives without loss of their biological activities.

Animals↗
PubMed1990

The anticancer effect of antineoplaston A-10 on human breast cancer serially transplanted to athymic mice.

We report the effects of Antineoplaston A-10 Injection on the growth curve of human breast cancer (R-27) serially transplanted to athymic mice. The intraperitoneal administration of 1/4 LD-50 (50 mg/mouse) of Antineoplaston A-10 Injection every day and 1/2 LD-50 (100 mg/mouse) every other day for 35 days was found to significantly inhibit the growth curve and also the 3H-TdR uptake was inhibited by 73.7% in those given 1/4 LD-50 and by 77.1% in those given 1/2 LD-50. The tumor histology in both groups showed necrosis but no lymphocyte infiltration.

Animals↗
PubMed1990

Catabolic effects of muramyl dipeptide on rabbit chondrocytes.

Muramyl dipeptide, an essential structure for the diverse biologic activities of bacterial cell wall peptidoglycan, inhibited the synthesis of glycosaminoglycan/proteoglycan in cultured rabbit costal chondrocytes in a dose-dependent manner. Muramyl dipeptide, as well as lipopolysaccharide and interleukin-1 alpha, also enhanced the release of 35S-sulfate-prelabeled glycosaminoglycan/proteoglycan from the cell layer, which seems to reflect, at least partially, the increasing degradation of glycosaminoglycan/proteoglycan. Five synthetic analogs of muramyl dipeptide known to be adjuvant active or adjuvant inactive were tested for their potential to inhibit synthesis of glycosaminoglycan/proteoglycan and to enhance the release of glycosaminoglycan/proteoglycan in chondrocytes. The structural dependence of these synthetic analogs on chondrocytes was found to parallel that of immunoadjuvant activity. These results suggest that muramyl dipeptide is a potent mediator of catabolism in chondrocytes.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1990

Association of hepatocellular carcinoma and a hyperplastic nodule after phosphate diethylstilbestrol therapy.

We treated a patient in whom a hepatocellular carcinoma and a hyperplastic nodule of the liver concomitantly grew in association with long term phosphate diethylstilbestrol therapy for a carcinoma of the prostate. A 72-year-old Japanese man was admitted for investigation of hepatic masses. A diagnosis of prostate carcinoma had been made seven years ago and phosphate diethylstilbestrol 200 mg daily had been prescribed. A small mass was first detected in the liver four years later and another mass appeared three years after the appearance of the first mass. Histology of the excised tissue showed the former mass to be a hyperplastic nodule and the latter one hepatocellular carcinoma. Findings of cirrhosis, hepatitis or fibrosis were nil but fatty metamorphosis of the hepatocytes was apparent. These histological changes were considered to be associated with long-term phosphate diethylstilbestrol therapy therefore careful follow-up using amazing diagnosis is recommended for patients on phosphate diethylstilbestrol therapy.

Aged↗