Biomedical subjects
Publications and source records attributed to J Yamamoto.
Mature 53 kDa histidine decarboxylase (HDC) peptide is produced from a precursor 74 kDa peptide. The mechanism of specific cleavage by processing enzyme is unknown. Using the recombinant mouse 74 kDa HDC, we found that porcine pancreatic elastase specifically converted the inactive 74 kDa HDC to its active form of 53 kDa HDC.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
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.
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)
Explore the source record for details and available documents.
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.
Explore the source record for details and available documents.
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.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
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.
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.
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.
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.
We examined the role of the myocardial beta-adrenoceptor-G protein-adenylate cyclase complex in 10-week-old Wistar rats with ischemic heart failure produced by ligating the left coronary artery (l) and in sham-operated control rats (C). We determined the number of beta-adrenoceptors (Bmax), the dissociation constant (Kd) using a binding assay and adenylate cyclase activity. Levels of mRNA encoding for the alpha subunit of the stimulatory guanine nucleotide-binding protein (Gs alpha) and the alpha subunit of the inhibitory guanine nucleotide-binding protein (Gi alpha) were measured by Northern blot analysis. The amounts of Gs alpha and Gi alpha were measured by Western blot analysis. Bmax and Kd did not differ significantly between the two groups: Bmax: l, 14.7 +/- 1.3 v C, 13.4 +/- 0.9 f mol/mg protein; Kd: l, 345 +/- 31 v C, 340 +/- 28 pM (mean +/- standard error, S.E.). There were no significant differences in Gs alpha and Gi alpha concentrations between the two groups as measured by Northern blot analysis (Gs alpha: l, 91.6 +/- 4.5 v C, 96.5 +/- 2.3%; Gia; l, 95.4 +/- 3.6 v C, 90.0 +/- 3.0%) or by Western blot analysis (Gs alpha: l, 95.2 +/- 2.0 v C, 94.5 +/- 2.6%; Gi alpha: l, 91.5 +/- 3.0 v C, 95.1 +/- 2.9%). Activity of basal and MnCl2-stimulated adenylate cyclase did not differ significantly in the two groups: basal: l, 7.5 +/- 0.7 v C, 8.1 +/- 0.5 pmol cAMP/mg protein/min; MnCl2 l, 80.8 +/- 5.8 v C, 86.4 +/- 6.7 pmol cAMP/mg protein/min. Sodium fluoride and forskolin-stimulated adenylate cyclase activity were significantly lower in the hearts with ischemic failure compared with controls (sodium fluoride: l, 68.5 +/- 5.6 v C, 103 +/- 4.8 pmol cAMP/mg protein/min; forskolin: l, 84.6 +/- 6.5 v C, 117.1 +/- 5.6 pmol cAMP/mg protein/min). These data suggest the presence of myocardial Gs alpha dysfunction in ischemic heart failure. We conclude that such a dysfunction in Gs alpha may contribute to the contractile abnormalities in ischemic heart failure.
Although gastric enterochromaffin-like (ECL) carcinoid tumors are known to develop in patients with long-standing hypergastrinemia, the expression of the gastrin receptor gene in ECL cells has not yet been demonstrated. Therefore, this study was designed to examine gastrin receptor gene expression in ECL cells. Mastomys gastric mucosal cells isolated by enzyme dispersion were separated into 10 fractions (F1-10) by centrifugal elutriation. Each fraction was examined histologically to determine whether they contained ECL and/or parietal cells and Northern blot analysis was used to confirm the presence of histidine decarboxylase and H+, K(+)-ATPase gene expression. ECL cells were found only in fractions 1 and 2, whereas parietal cells were detected in fractions 6-10. Gastrin receptor gene expression was demonstrated in both parietal cell-rich and ECL cell-rich fractions. In addition, the gastrin receptor cDNA sequences obtained from the two of the fractions (F1 and 8) were identical. These results suggest that gastrin receptor genes are expressed in ECL cells as well as in parietal cells and that these receptors are identical.