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Biomedical subjects

J Yamamoto

Publications and source records attributed to J Yamamoto.

At least 181 records · Page 10Linked to original sources
PubMed1995

Messenger RNA for the guanine nucleotide-binding regulatory protein (G protein) is reduced in the acute ischemic myocardium.

It has been reported that the function of the guanine-binding regulatory protein (G protein), especially the alpha subunit of the stimulatory G protein (Gs alpha), in myocardium is decreased with acute ischemia. However, it is unclear whether this decrease is due to transcriptional or post-transcriptional changes. Moreover, no studies have examined the distribution of G protein mRNA in ischemic myocardium using in situ hybridization. The purpose of this study was to explore alterations in mRNA of G proteins (Gs and Gi) in ischemic hearts using in situ hybridization. We measured the levels of mRNA for Gs alpha and Gi alpha in ischemic and non-ischemic myocardium by in situ hybridization using a radioisotope imaging system. We compare these mRNA levels in ischemic and non-ischemic myocardium with Northern blot analysis and the protein levels of G proteins by Western blot analysis. The mRNA for Gs alpha and Gi alpha was distributed diffusely in normal hearts. Levels of mRNA detected by in situ hybridization were substantially reduced by acute ischemia, and these results were confirmed by Northern and Western blot analysis. These results suggest that decreased levels of mRNA and protein for G proteins may underlie the impaired function of the receptor--G protein--adenylate cyclase system in ischemic myocardium. In addition, quantitative evaluation of mRNA is possible by in situ hybridization and correlates well with Northern analysis.

Acute Disease↗
PubMed1995

Activin and inhibin have opposite effects on steroid 5 alpha-reductase activity in genital skin fibroblasts.

The transforming growth factor beta (TGF-beta) superfamily includes several closely related peptides including the activins and inhibins. Since we recently reported that TGF-beta 1 and beta 2 are potent inducers of steroid 5 alpha-reductase (5 alpha R), we have now studied the effects of these other peptides using primary cultures of human scrotal skin fibroblasts. Recombinant human activin A or inhibin A were added to cultured cells (2 x 10(5) cells) for 2 days in a serum free media and 5 alpha R activity was measured by the %-conversion of tracer [3H]-testosterone to dihydrotestosterone (DHT) over a 4-h period. Activin significantly stimulated 5 alpha R activity in a dose related manner (control 3.0 +/- 0.4%, activin (1.2 x 10(-9) M) 6 +/- 0.7%, P < 0.01, (2.4 x 10(-9) M) 8.5 +/- 0.6%, P < 0.001). In comparison, androgen (DHT 10(-7) M) induction of 5 alpha R was 4.7 +/- 0.2%, P < 0.05. Combined exposure of fibroblasts to activin (1.2 x 10(-9) M) and androgen (10(-7) M) did not result in additive or synergistic effect on 5 alpha R activity. In contrast, exposure of cells to an androgen (10(-7) M) and TGF-beta (2 x 10(-10) M) led to synergistic effects on 5 alpha R activity (control 1.5 +/- 0.1%, DHT 2.6 +/- 0.2% TGF-beta 1 4.8 +/- 0.5, TGF-beta 1 + DHT 9.2 +/- 1.2%).(ABSTRACT TRUNCATED AT 250 WORDS)

3-Hydroxysteroid Dehydrogenases↗
PubMed1995

Pathologic support for limited hepatectomy in the treatment of liver metastases from colorectal cancer.

OBJECTIVE: The authors determined an appropriate surgical treatment for liver metastases from colorectal cancers. Clinicopathologic features of metastatic lesions of colorectal cancers were studied. SUMMARY BACKGROUND DATA: Major hepatic resection is the usual procedure for treatment of hepatic metastases from colorectal cancers. METHODS: Forty consecutive patients who underwent hepatic resections were prospectively studied, for a total of 89 metastatic liver tumors. RESULTS: Metastatic tumor often extended along Glisson's capsule, including invasion to the portal vein (9 cases), the hepatic vein (3 cases), the bile duct (16 cases), and the nerve (6 cases). The main tumor had small satellite nodules in only one patient, and there were no microscopic deposits in the parenchyma, even within 10 mm from the metastatic tumors. Fibrous pseudocapsule formation was observed in 28 patients. DISCUSSION: The rarity of intrahepatic metastasis from metastatic tumor supports nonanatomic limited hepatic resection as the procedure of choice for metastatic colorectal cancer in the liver. The spread via Glisson's capsule should be taken into consideration for complete tumor clearance.

Adenocarcinoma↗
PubMed1995

A case of glycogen storage disease type III (glycogen debranching enzyme deficiency) with liver cirrhosis and hypertrophic cardiomyopathy.

We present a 26-year-old woman with glycogen storage disease type III (debranching enzyme deficiency) complicated with liver cirrhosis and hypertrophic cardiomyopathy. Glycogen debranching enzyme has two catalytic sites, oligo-1,4,-1,4- glucantransferase (EC 2.4.1.25) and amylo-1,6-glucosidase (EC 3.2.1.33). Variability in the clinical phenotype could be a function of the involvement of one or other catalytic site, or differences in tissue expression of the defective enzyme, or both. We hypothesize that some subtypes of glycogen storage disease (GSD) type III may cause liver cirrhosis as seen in GSD type IV due to the accumulation of glycogen of abnormal structure.

Adult↗
PubMed1995

n-3 and n-6 fatty acid intake and serum phospholipid fatty acid composition in middle-aged women living in rural and urban areas in Okayama Prefecture.

Dietary fatty acids and serum lipids were evaluated in 68 middle-aged women living in the northern, rural area of Okayama Prefecture, and were compared with the values obtained from 65 urban women from the southern part of this prefecture. A higher level in HDL cholesterol and a lower atherogenic index were observed in the rural women. The percent of energy intake as fat was lower (20.4 +/- 0.8% vs. 23.2 +/- 0.7%) and that of carbohydrate was greater in the rural group. Eicosapentaenoic (EPA, 0.41 +/- 0.04 g/day) and docosahexaenoic acid (DHA, 0.70 +/- 0.08 g/day) intakes were significantly higher in the rural subjects than in the urban group. Significantly higher DHA levels and n-3/n-6 fatty acid ratios in serum total phospholipids were found in rural women in their fifties and the sixties compared to urban women. Dietary linoleic acid (LA) amounts were positively correlated with LA (p < 0.05), and negatively with the EPA (p < 0.05) and DHA (p < 0.01) contents of serum total phospholipids. These results suggest that the traditional Japanese diet, containing little fat but enriched in complex carbohydrates and n-3 fatty acids of marine origin, may be related to the low atherogenic index in this rural area.

Adult↗
PubMed1995

De Novo synthesis and posttranslational processing of L-histidine decarboxylase in mice.

We purified L-histidine decarboxylase from mouse mastocytoma cells and cloned mouse HDC cDNA, and found that the primary translated product (74 kD) is posttranslationally processed in its C-terminal region to yield a native HDC subunit (53 kD). Recombinant 74-kD, but not 53-kD HDC species was present mainly in the particulate fraction of Sf9 cells. The particulate 74-kD recombinant HDC was cleaved by porcine pancreatic elastase, and a homodimer of a 53-kD subunit having the identical catalytic properties to those of native HDC was solubilized. The particulate HDC from mouse stomach was partially purified and it was solubilized by porcine pancreatic elastase to yield the 53-kD subunit of HDC. We identified endogenous proteolytic activity, which converts the particulate recombinant 74-kD HDC to the soluble 53-kD HDC in the supernatant of mouse stomach. In mastocytoma cells, we demonstrated that the induction of HDC activity and HDC mRNA synergistically occurred upon treatment with dexamethasone + TPA, and also with cAMP + Ca2+. On a genomic DNA cloning, we found that two upregulations occurred via the involvement of the regulatory elements binding to the sequences from -132 to -53 and -267 to -53, respectively.

Animals↗
PubMed1994

The antithrombotic effect of human activated protein C on He-Ne laser-induced thrombosis in rat mesenteric microvessels.

The effect of activated protein C (APC) on He-Ne laser-induced thrombosis in rat mesenteric microvessels was studied. APC inhibited platelet-rich thrombus formation in a dose-dependent manner more significantly in venules but also in arterioles. Inhibition of thrombus formation was maximal immediately after intravenous administration and persisted for 40 minutes in venules and 20 minutes in arterioles. The maximum effective blood concentration of APC was 1.04 micrograms/ml. A small but statistically significant prolongation of the activated partial thromboplastin time (APTT) was observed at this blood concentration, demonstrating the anticoagulant effect of APC. Our findings show that APC has a significant inhibitory effect on platelet thrombus formation and suggest that APC is a potent natural antithrombotic agent.

Animals↗
PubMed1994

Chloride ions catalyze the formation of cis adducts in the binding of anti-benzo[a]pyrene diol epoxide to nucleic acids.

The alkylation of DNA by racemic 7r,8t-dihydroxy-9t,10t-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (anti-BPDE) exhibits a strong preference for formation of trans adducts between the N2 deoxyguanosine alkylation site and the (+)-enantiomer of anti-BPDE. In the presence of 10 mM buffer with no added salt, 98% of the adducts formed with native calf thymus DNA result from trans opening of the epoxide ring. The strong selectivity for trans adduct formation obtained with duplex DNA at low salt concentration is found to a lesser degree with poly(G) but is nearly absent with dAMP. When DNA adducts are formed in 10 mM MgCl2 or 1 M NaCl, the proportion of cis adducts increases to approximately 7 and approximately 26%, respectively. At low salt, 10 mM MgCl2, and 1 M NaCl, deoxyguanosine adducts are approximately 1%, 6%, and 24% cis, whereas deoxyadenosine adducts are approximately 11%, 14%, and 37% cis, respectively. NaCl also increases the proportion of cis adducts formed with poly(G) and dAMP. It is proposed that the increase in cis-adduct formation due to salt results from SN1 attack of chloride ion on the BPDE carbocation, forming a trans chlorohydrin, followed by SN2 attack of DNA.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗
PubMed1994

An isolated, complete resection of the caudate lobe, including the paracaval portion, for hepatocellular carcinoma.

An isolated resection of the entire caudate lobe, including the paracaval portion, was performed in a 68-year-old man with hepatocellular carcinoma complicated by chronic hepatitis. Precise resection of the paracaval portion, which surrounds the right side of the inferior vena cava, is difficult because of its deep location and the lack of superficial landmarks indicating its margins. Using a counterstaining technique to define the right margin and the transhepatic anterior approach to access the ventral border, the paracaval portion, with the spigelian lobe and the caudate process, was completely resected without sacrificing the other part of the liver. The whole procedure was performed without blood transfusion, and the postoperative course of the patient was uneventful. This procedure would add a new option for surgical management of hepatic malignancies originating in the caudate lobe of the compromised liver.

Aged↗
PubMed1994

Using the brief symptom inventory to profile monolingual Spanish-speaking psychiatric outpatients.

As part of a larger study (Acosta, Evans, Hurwicz, & Yamamoto, 1987), a translated version of the Brief Symptom Inventory (BSI) was given to 153 monolingual Spanish-speaking psychiatric outpatients in the Los Angeles area. The raw mean scores on the nine primary symptom dimensions and the Global Severity Index (GSI) of the Spanish-speaking population were compared with the published raw mean scores of a normative sample of English-speaking psychiatric outpatients. Results suggested that the Spanish-speaking population had higher symptom levels on several dimensions and the GSI. It was suggested that the BSI could be a potentially useful instrument for self-reported psychiatric symptomatology among the Spanish-speaking population if an appropriate translation of the BSI were used.

Adult↗