Biomedical subjects
A Wada
Publications and source records attributed to A Wada.
Conotoxin GIIIA: selective inhibition of 22Na influx via voltage-dependent Na channels in adrenal medullary cells.
Conotoxin GIIIA and GIIIB from the marine snail Conus geographus have been reported to inhibit voltage-dependent Na channels in skeletal muscle and postganglionic sympathetic neuron, but have no effect on Na channels in brain, giant axon and heart. In eel electroplax, conotoxins were also shown to share the common binding sites with saxitoxin (see review Gray et al. 1988). In bovine adrenal medullary cells, conotoxin GIIIA inhibited veratridine-induced influx of 22Na, 45Ca and secretion of catecholamines with an IC50 of 6 mumols/l while saxitoxin suppressed veratridine-induced responses with an IC50 of 6.3 nmol/l. [3H]Saxitoxin binding to the cells was inhibited by unlabeled saxitoxin with an IC50 of 5.1 nmol/l, but was slightly reduced by 10 mumols/l conotoxin GIIIA. Conotoxin GIIIA, at 10 mumols/l, did not alter carbachol-induced influx of 22Na, 45CA and secretion of catecholamines as well as high K-induced 45Ca influx and catecholamine secretion. These results indicate that conotoxin GIIIA, at concentrations 950 fold higher than saxitoxin, inhibits Na influx via voltage-dependent Na channels, but has no effect on the nicotinic receptor-ion channel complex or the voltage-dependent Ca channels. Conotoxin GIIIA seems to bind at the sites which are distinct from saxitoxin, but are functionally linked to the voltage-dependent Na channels. Conotoxins may be useful for the classification of Na channels in excitable cell membranes.
Doublet preference and gene evolution.
Doublet preference analysis was carried out on coding and noncoding regions of Escherichia coli, Saccharomyces cerevisiae, and human mitochondrial and nuclear DNA. The preference pattern in 1-2 and 2-3 doublets in E. coli and S. cerevisiae correlated with that in noncoding regions. The 3-1 doublet preference in E. coli genes with low optimal codon frequency and in S. cerevisiae genes also showed a correlation with each of their noncoding doublet preference. A mechanism to explain these double preference correlations in doublet preference is presented: mutational biases, the origin of the noncoding region doublet preference, evolved so as to maintain the 1-2 and 2-3 doublet preference, which is determined by codon usage. These biases then acted on the 3-1 doublet, which was almost free of coding constraints, resulting in a similar preference in this doublet.
Structure and probable genetic location of a "ribosome modulation factor" associated with 100S ribosomes in stationary-phase Escherichia coli cells.
The decrease in overall translation activity occurring concomitantly with the transition from the exponential growth phase to the stationary phase of Escherichia coli cells was found to be accompanied by the appearance of 100S ribosomes (dimers of 70S ribosome monomers). Analysis of ribosomal proteins by the radical-free and highly reducing method of two-dimensional gel electrophoresis indicated that a protein, designated protein E, was exclusively associated with 100S ribosomes. From the results, we propose that protein E is a "ribosome modulation factor" (RMF), which associates with 70S ribosomes and converts them to a dimeric form. A homology search of the partial amino acid sequence of RMF using the DNA sequence data bases revealed that the rmf gene, which encodes RMF, is located next to the fabA gene at 21.8 min on the E. coli chromosome.
Sodium/proton exchange in cultured bovine adrenal medullary cells.
We investigated the presence of Na+/H+ exchange in cultured bovine adrenal medullary cells. The intracellular pH in control cells measured by 5,5-dimethyl[2-14C]oxazolidine-2,4-dione was 7.13 +/- 0.02 (n = 6). Removal of Na+ from the incubation medium shifted the intracellular pH down to 6.67 +/- 0.12 (n = 6). Reintroduction of Na+ to the medium caused a rapid recovery in intracellular pH to 7.20-7.30 that was associated with an increase in uptake of 22Na+ by the cells. Both increases in intracellular pH and uptake of 22Na+ were inhibited by amiloride, an inhibitor of Na+/H+ exchange. The recovery of intracellular pH by addition of Na+ was partially inhibited by quinidine, another inhibitor of Na+/H+ exchange, but not by 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid, an anion-exchange (Cl-/HCO3-) inhibitor. Li+ could substitute for Na+ in the recovery of intracellular pH. Carbachol caused an increase in intracellular pH from 7.12 +/- 0.01 to 7.21 +/- 0.02 (n = 10). This increase in intracellular pH caused by carbachol was inhibited by amiloride. These results suggest the existence of an amiloride-sensitive Na+/H+ exchange that regulates the intracellular pH in adrenal medullary cells.
[Rapid detection and identification of mycobacterial DNA by PCR].
We have developed a highly sensitive and rapid PCR assay for detection and identification of mycobacterial species. Two sets of PCR primers were prepared; one was for the 19 kDa antigen gene and the other for the dna J gene. The PCR for 19 kDa antigen gene was found to be specific to the M. tuberculosis complex; M. tuberculosis, M. bovis and M. africanum. On the other hand, the PCR for the dna J gene was able to detect a broad spectrum of mycobacterial species including M. tuberculosis, M. avium, M. intracellulare and M. kansasii. The sensitivity of PCR was similar to that of the culture method for precultured M. tuberculosis whereas PCR was much more sensitive than the culture for clinical samples. The procedure of decontamination by sodium hydroxide for clinical samples could reduce the viability of M. tuberculosis while it did not affect mycobacterial DNA. The nucleotide sequence homologies among major mycobacteria were also determined following PCR for the dna J gene. This allowed us to make restriction maps for each mycobacterium. We have demonstrated that the PCR-RFLP for the dna J gene will be a useful laboratory test for rapid identification of tuberculous and nontuberculous mycobacterial species.
[Assessment of infarct-related coronary arteries using the bull's eye view method and unfolded surface mapping in thallium-201 myocardial tomography].
Infarct-related coronary lesions and collaterals were assessed by the bull's eye view and the unfolded surface map derived from thallium-201 myocardial tomography (Tl-201 SPECT) in 25 patients with anterior myocardial infarction. The patients were categorized in six groups according to their cine-angiographic findings: locations of stenosis (proximal or distal portions of the first diagonal branch or distal site of the first septal branch), and the presence or absence of collaterals. The anterior half of the left ventricle on the bull's eye view map was divided into eight regions from the anterior septum to the lateral wall and from the apex to the cardiac base. Tl-201 SPECT images were expressed as functional maps using maximum-count circumferential profile analysis: an "extent image" showing the extent of perfusion defect, and a "severity image" demonstrating the degree of hypoperfusion. The following results were obtained: 1. Perfusion defect of the "extent image" at the basal portion of the anterior septum reflected poor collaterals, with a sensitivity of 81.3%, a specificity of 77.8%, and a diagnostic accuracy of 80.0%. 2. Coronary stenosis at segment 6 (AHA classification) was differentiated from that at segment 7 by detecting hypoperfusion at the basal septum on the "severity image", with a sensitivity of 71.4%, a specificity of 77.8%, and a diagnostic accuracy of 75.0%. 3. Perfusion defect at the basal section of the proximal portion of the anterior wall on the "extent image" indicated stenosis at the proximal segment 6, with a sensitivity of 57.1% and a specificity of 88.9%.(ABSTRACT TRUNCATED AT 250 WORDS)
Long-term survival after brain metastasis from endometrial cancer.
A case is reported of prolonged survival after radical hysterectomy for poorly differentiated adenocarcinoma of the endometrium and resection of metastatic carcinoma of the brain followed by radiation therapy. The 43-year-old patient has survived for seven years after hysterectomy and six years 10 months after excision of the brain metastasis. Our results show that the surgical excision of a single metastatic lesion of the brain with postoperative irradiation offers hope of prolonged survival in patients with a solitary brain metastasis and no evident systemic disease.
Solid and papillary neoplasm arising from an ectopic pancreas in the mesocolon.
A case of solid and papillary neoplasm of a mesocolonic ectopic pancreas in a 13-yr-old girl is presented. An 8-cm, well-encapsulated, and partly calcified tumor which protruded from the mesocolon was resected surgically. Histologically, the tumor showed either solid sheets or papillary arrangements (around the vascular core) of uniformly small cells with alpha 1-antitrypsin-positive cytoplasm. Some of the tumor cells had zymogenlike granules, suggesting acinar cell differentiation. At the base of this tumor, small pancreatic tissues (islet, acinar, and ductular cells) were detected in the mesocolonic tissue. Incidences of both ectopic pancreas outside the gastrointestinal wall and solid and papillary neoplasm of the pancreas are rare, and this is the first case reported in the literature.
Morphologic characteristics of pancreatic carcinoma with diabetes mellitus.
For 81 cases of resectable pancreatic carcinoma, the site of cancer origin, cancer histologic features, and hyperplasia in the noninvolved duct were studied in relation to diabetes. They were classified into the following three groups: (1) fasting blood sugar (FBS) of less than 120 mg/dl (Group A, 26 cases); (2) FBS of more than 120 mg/dl with less than 2-year history of diabetes (Group B, 38 cases); and (3) FBS of more than 120 mg/dl with more than a 2-year history of diabetes (Group C, 17 cases). Although neither tumor size nor tumor location differed between the three groups, both the highest resectability (47%) and the lowest rate (71%) of extrapancreatic invasion were seen in Group C. A pancreatic ductogram showed that the pattern of the main pancreatic duct was intact in 0% in Group C versus 35% in Group A (P less than 0.05). Histologically, papillary/well-differentiated adenocarcinoma was present in 35% of Group A patients versus 61% of Group B and 71% of Group C patients (P less than 0.05). Papillary hyperplasia was present in the ducts of 27% of the patients in Group A; this was significantly lower than the other two groups. Atypical duct hyperplasia was present in 47% of Group C patients; this was significantly higher than in the other two groups. It appears that cells in the main pancreatic duct are vulnerable to hyperplastic and well-differentiated cancerous changes in patients with a history of diabetes of more than 2 years duration.
Novel third-letter bias in Escherichia coli codons revealed by rigorous treatment of coding constraints.
A novel bias in codon third-letter usage was found in Escherichia coli genes with low fractions of "optimal codons", by comparing intact sequences with control random sequences. Third-letter usage has been found to be biased according to preference in codon usage and to doublet preference from the following first letter. The present study examines third-letter usage in the context of the nucleotide sequence when these preferences are considered. In order to exclude any influence by these factors, the random sequences were generated such that the amino acid sequence, codon usage, and the doublet frequency in each gene were all preserved. Comparison of intact sequences with these randomly generated sequences reveals that third letters of codons show a strong preference for the purine/pyrimidine pattern of the next codons: purine (R) is preferred to pyrimidine (Y) at the third site when followed by an R-Y-R codon, and pyrimidine is preferred when followed by an R-R-Y, an R-Y-Y or a Y-R-Y codon. This bias is probably related to interactions of tRNA molecules in the ribosome.
Role of glucose-6-phosphate dehydrogenase on enhanced proliferation of pre-neoplastic and neoplastic cells in rat liver induced by N-nitrosomorpholine.
The relationship between G6PD and the number and size of pre-neoplastic and neoplastic lesions in rat liver was examined. Male Sprague-Dawley rats were given drinking water containing 250 mg/l of NNM for 8 weeks. Pre-neoplastic and neoplastic lesions with positive staining of GT were classified histochemically into G6PD-positive and G6PD-negative lesions. At week 24, quantitative analysis showed that the incidence and number of G6PD-positive lesions were significantly higher than those of G6PD-negative lesions. Histologically, hepatocellular carcinomas were more frequent and larger in G6PD-positive lesions than in G6PD-negative ones. Statistical analysis of the quantitative data also showed that the number and volume of G6PD-positive hepatocellular carcinomas were significantly higher than in G6PD-negative carcinomas. The G6PD-positive pre-neoplastic lesions had a significantly higher labelling index than G6PD-negative ones. These findings revealed a considerable difference in the growth of these 2 populations of the lesions, and indicate that G6PD activity may be closely related to proliferation of the pre-neoplastic and neoplastic cells in the liver.
Clinical and histopathological appraisal of preoperative irradiation for adenocarcinoma of the pancreatoduodenal region.
A retrospective review to elucidate the rationale of preoperative irradiation was made on 18 carcinomas of the head of the pancreas area. After 50 Gy/25 fractions of 10 MV X-ray was given, all 18 tumors decreased from 3.3 +/- 0.8 cm to 2.0 +/- 0.7 cm. At the surgical operation, 16 patients (89%) received pancreatic resection, without operative death. Histologically, in 13 of these 16 cases, the population of severely degenerative cancer cells (SDCC) was more than 1/3 of all cancer cells, and SDCCs were likely to locate at the periphery (advancing point of carcinoma). These histological patterns were considered as favorable to improve the operative curability. However, in the remaining three cases, the SDCC population was less than 1/3. In addition, nonaffected (i.e., viable) cancer cells were detected at the periphery, and this is an extremely adverse condition for subsequent surgery. Chronic pancreatitis in the noncancerous area was present in these three cases, but not in the 13 cases. Therefore, the most significant factor that predicts the radioresistance especially at the periphery of the carcinoma was considered to be coexisting chronic pancreatitis.
Veratridine-induced phosphorylation and activation of tyrosine hydroxylase, and synthesis of catecholamines in cultured bovine adrenal medullary cells.
The mechanism of the synthesis of catecholamines by veratridine was studied in cultured bovine adrenal medullary cells. (1) Veratridine increased the phosphorylation and activity of tyrosine hydroxylase as well as the synthesis of [14C]catecholamines from [14C]tyrosine, all of which were inhibited by tetrodotoxin. Veratridine-induced activation of tyrosine hydroxylase and synthesis of [14C]catecholamines were reduced in 20 mmol/l extracellular Na+ or in Ca2+-free medium. (2) 12-O-Tetradecanoylphorbol-13-acetate (TPA), an activator of protein kinase C, increased the synthesis of [14C]catecholamines. In the presence of TPA, veratridine did not produce any additional increase in [14C]catecholamine synthesis. In protein kinase C-deficient cells which were prepared by pretreatment with 1 mumol/l TPA for 24 h, TPA failed to increase [14C]catecholamine synthesis and veratridine-induced [14C]catecholamine synthesis was suppressed by 50%. (3) Polymyxin B, an inhibitor of protein kinase C and N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7), an inhibitor of calmodulin, inhibited veratridine-stimulated synthesis of [14C]catecholamines as well as veratridine-induced influx of 22Na+ and 45Ca2+ with similar potencies. (4) In digitonin-permeabilized cells, polymyxin B attenuated the activation of tyrosine hydroxylase caused by Ca2+. These results suggest that veratridine-induced synthesis of catecholamines and activation of tyrosine hydroxylase were mediated by Ca2+-dependent phosphorylation of this enzyme, and protein kinase C may be responsible, at least in part, for this process.
Inhibition by vecuronium of carbachol-induced influx of 22Na+, 45Ca2+ and secretion of catecholamines in cultured bovine adrenal medullary cells.
In cultured bovine adrenal medullary cells, vecuronium, pancuronium and D-tubocurarine reduced carbachol-induced 45Ca2+ influx and catecholamine secretion by inhibiting 22Na+ influx via nicotinic receptor-ion channel complex with IC50 values of 0.43, 7.6 and 3.9 mumol/l, respectively. IC50 values of pancuronium and D-tubocurarine observed in adrenal medulla were one order of magnitude higher than the plasma concentrations of these muscle relaxants reported to produce 50% neuromuscular blockade, while IC50 of vecuronium was quite close between adrenal medulla and skeletal muscle.
Conformational change of bovine serum albumin by heat treatment.
The thermal denaturation of bovine serum albumin (BSA) was studied at pH 2.8 and 7.0 in the range of 2-65 degrees C. The relative proportions of alpha-helix, beta-structure, and disordered structure in the protein conformation were determined as a function of temperature, by the curve-fitting method of circular dichroism spectra. With the rise of temperature at pH 7.0, the proportion of alpha-helix decreased above 30 degrees C and those of beta-structure and disordered structure increased in the same temperature range. The structural change was reversible in the temperature range below 45 degrees C. However, the structural change was partially reversible upon cooling to room temperature subsequent to heating at 65 degrees C. On the other hand, the structural change of BSA at pH 2.8 was completely reversible in the temperature range of 2-65 degrees C, probably because the interactions between domains and between subdomains might disappear due to the acid expansion. The secondary structure of disulfide bridges-cleaved BSA remained unchanged during the heat treatment up to 65 degrees C at pH 2.8 and 7.0.
Quantification of area and percentage of infarcted myocardium by single photon emission computed tomography with thallium-201: a comparison with serial serum CK-MB measurements.
In order to quantify the size of the infarcted myocardium, two kinds of data processing techniques were applied to single photon emission computed tomography (SPECT) with thallium-201 and its clinical reliability was evaluated by comparing it with the infarct sizing procedure with the serial serum creatine kinase-MB measurements in 14 patients with acute myocardial infarction. After maximum-count circumferential profile analysis, short axis images were reformatted into an unfolded surface map and a bull's eye view map. The SPECT-determined infarct size was defined as the area or the percentage of hypoperfused myocardium of which the profile count was less than the mean minus 2SD derived from 8 normal subjects. The infarct area was calculated from the number of pixels with an abnormal count and expressed in an unfolded surface map. The percentage was calculated from the number of abnormal profile points and displayed in a bull's eye view map. A high linear correlation was observed between the enzymatically determined infarct size and the infarct area or the percentage (r = .947, r = .872, respectively), despite underestimations in 2 patients with accompanying right ventricular infarction and overestimations in 2 patients with prior anterior infarction. Moreover, a close negative correlation was found between the left ventricular ejection fraction and the infarct area or the percentage (r = .836, r = .821, respectively). Thus, the semiautomatic techniques for processing thallium-201 SPECT images might contribute to the quantitative estimation and display of infarcted myocardium and have high clinical reliability.
cis-unsaturated fatty acids stimulate catecholamine secretion, tyrosine hydroxylase and protein kinase C in adrenal medullary cells.
In digitonin-permeabilized bovine adrenal medullary cells, arachidonic acid and oleic acid, the cis-unsaturated fatty acids, enhanced Ca2+-induced secretion of catecholamines, whereas elaidic acid, a trans-unsaturated fatty acid and stearic acid, a saturated fatty acid, had no effect. Indomethacin, an inhibitor of cyclooxygenase and nordihydroguaiaretic acid, an inhibitor of lipoxygenase, failed to inhibit the stimulatory effect of arachidonic acid. Stimulation of catecholamine secretion by arachidonic acid was abolished by the removal of adenosine 5'-triphosphate and Mg2+ from the incubation medium. Pretreatment of the cells with phorbol 12-myristate 13-acetate, an activator of protein kinase C, enhanced Ca2+-induced catecholamine secretion. In cells pretreated with phorbol 12-myristate 13-acetate, the stimulatory effect of arachidonic acid on Ca2+-induced catecholamine secretion was greatly reduced. In digitonin-permeabilized cells, arachidonic acid and oleic acid enhanced Ca2+-induced activation of tyrosine hydroxylase in the presence of adenosine 5'-triphosphate and Mg2+, whereas elaidic acid and stearic acid did not activate the enzyme. In a soluble fraction of adrenal medullary cells, 32P incorporation to histone by protein kinase C was increased by arachidonic acid and oleic acid, but not by elaidic acid and stearic acid. These results suggest that cis-unsaturated fatty acids modulate Ca2+-induced catecholamine secretion and tyrosine hydroxylase activity by activation of protein kinase C in adrenal medullary cells.