Biomedical subjects

K Yano

Publications and source records attributed to K Yano.

At least 505 records · Page 28Linked to original sources

PubMed1991

Dissociation of IgG antibody-mediated clumps of Trypanosoma brucei gambiense by complement.

Aggregated trypanosome masses that had formed in the region of equivalence in the absence of complement were readily dissociated by complement. Complement-mediated dissociation of the clumped trypanosomes in the area of equivalence released approximately 50% of the previously bound surface antigens. These antigens were capable of rebinding to new IgG antibody. Experiments indicated that complement deposition altered the bivalent IgG antibody in the immune complex into a univalent form. The occurrence of such an event in the presence of complement provides a great advantage to the infected host in the killing of pathogens in vivo, as it enables a greater number of antibodies to attach to surface antigens and subsequently initiate complement activity.

Animals↗

PubMed1991

Introduction of monoclonal antibodies to bromodeoxyuridine to monitor hepatic regeneration.

The effect on the liver of portal vein and/or bile duct branch ligation was examined in rabbits by measuring cellular kinetics using the bromodeoxyuridine labeling index. Twenty-four days after ligation of a portal vein and/or bile duct branch, similar degrees of compensatory regeneration were observed. However, there were significant differences in the pattern in which regeneration developed. Compensatory regeneration after ligation of a bile duct follows a different pattern than that after portal vein branch ligation.

Animals↗

PubMed1991

Characteristics of respondents and nonrespondents in a prospective study of osteoporosis.

During 1981-1982, a cohort of elderly Japanese Americans living in Hawaii was recruited for an epidemiologic study of osteoporosis. The male subjects were simultaneously being examined for an epidemiologic study of heart disease. Baseline data collected from both the men and women at a previous heart disease examination were used to compare responders vs nonresponders. The target population for the osteoporosis study consisted of 1685 men and 1594 women. Of these, 1379 men (81.8%) and 1105 women (72.0%) participated in the initial osteoporosis examination. For each sex, nonrespondents were older and had higher systolic blood pressure levels than did the respondents. Male nonresponders had a higher stroke prevalence and more frequent recent use of vasodilator medicine. Female nonresponders had a less frequent history of having ever taken female hormones than did the responders. The responders and nonresponders were reasonably similar in other respects, as indicated by the comparison of more than 40 other variables. This suggests that nonresponse bias is probably not a major influence in exposure-disease associations in this osteoporosis cohort. We believe this is the first published report dealing with nonresponse characteristics in a cohort study of osteoporosis.

Aged↗

PubMed1991

Hypocalcemic focal seizures in a one-month-old infant of a mother with a low circulating level of vitamin D.

We present a case of a one-month-old infant with hypocalcemia and rickets, with symptoms of focal seizures. The ictal EEG showed left occipital spikes spreading over all of the left hemisphere. From the laboratory studies, we concluded that a low maternal circulating level of vitamin D would cause infantile hypocalcemia and rickets, while immature renal response to parathyroid hormone and transient hypoparathyroidism in infancy would induce hyperphosphatemia. Hypocalcemia may be an important factor in the cause of focal seizures which start even after the age of one month. Further, investigation of maternal vitamin D levels should be done in infantile hypocalcemia.

Adult↗

PubMed1991

The effect of defined media, additive nutrients and metabolites on the development of the sporogony cycle of Plasmodium berghei in Anopheles stephensi.

Anopheles stephensi mosquitoes were infected with Plasmodium berghei by feeding on parasitaemic hamsters. After the infective blood meal they were separated into groups that were maintained on sugar solutions containing different additives. The numbers of oocysts developing in the various groups were then compared. When either casein, haemoglobin or foetal bovine serum was added to the sugar, the yield of oocysts was 1.6-2.1 times higher than that in controls fed only on sugar solutions. When either medium 199, Leibovitz's formulated L15 (L15-B) or 'B' compounds alone were added, the yield of oocysts was 2.3-2.9 times higher than that in the controls. The addition of p-aminobenzoic acid, hypoxanthine, methiolnine, or fractions of 'B' had no significant effect on the number of oocysts.

Animals↗

PubMed1991

CYP52 (cytochrome P450alk) multigene family in Candida maltosa: molecular cloning and nucleotide sequence of the two tandemly arranged genes.

Southern blot analysis under low-stringency conditions using a previously isolated n-alkane-inducible cytochrome P450 (P450alk) gene as a probe revealed the presence of multiple P450alk-related genes in the genome of Candida maltosa. Nine P450alk-related genes (one reported previously and eight in the present report) were isolated from a genomic library constructed from this strain, and these were classified on the basis of sequence similarities into three pairs of putative allelic genes and three nonallelic genes. Two pairs of these alleles were tandemly arranged in the genome. The complete nucleotide sequences of one of these pairs were determined and compared to other members of this P450 family (CYP52) in C. maltosa and C. tropicalis. Northern blot analysis further showed that these genes were regulated by carbon sources. These results provide evidence for a P450alk (CYP52) multigene family in C. maltosa.

Amino Acid Sequence↗

PubMed1991

Arrhythmogenic properties of the ventricular myocardium in cardiomyopathic Syrian hamster, BIO 14.6 strain.

STUDY OBJECTIVE: Incidence of spontaneous cardiac arrhythmias and inducibility of ventricular arrhythmias in the cardiomyopathic hamster, BIO 14.6 strain, were examined. DESIGN: A 3 min electrocardiogram (ECG) was recorded weekly to 50 weeks of age. Programmed ventricular stimulation was then performed with single and double ventricular premature stimuli during both sinus rhythm and ventricular pacing, and with brief bursts of ventricular pacing to induce ventricular arrhythmias. EXPERIMENTAL MATERIAL: 19 male cardiomyopathic and 10 age matched normal hamsters from 16 to 50 weeks were used for recording the 3 min ECG; 11 cardiomyopathic and 10 normal hamsters aged 50 to 55 weeks were used for the induction of ventricular arrhythmias. MEASUREMENTS AND MAIN RESULTS: Spontaneous and sporadic ventricular premature contractions were documented in 8.3% of 218 ECGs from the cardiomyopathic hamsters between the ages of 30 and 46 weeks, whereas no ventricular arrhythmia was recorded in normal hamsters throughout the entire follow up period. Non-sustained ventricular tachycardia (NSVT) was induced in 7/11 cardiomyopathic hamsters by single ventricular premature stimulus. Either NSVT or ventricular fibrillation was induced in all cardiomyopathic hamsters with a significantly prolonged intraventricular conduction delay and refractory period. In contrast, neither NSVT nor ventricular fibrillation was induced in normal hamsters. CONCLUSION: This study provides the first evidence of the high arrhythmogenicity of the ventricles in cardiomyopathic hamsters.

Animals↗

PubMed1991

Expression of RNase Rh from Rhizopus niveus in yeast and characterization of the secreted proteins.

The full-length cDNA encoding RNase Rh, which is secreted extracellularly by Rhizopus niveus, was isolated and its nucleotide sequence was determined. It was placed under control of the promoter of the glyceraldehyde 3-phosphate dehydrogenase gene of Saccharomyces cerevisiae in a high expression vector in yeast. Since yeast cells transformed by this plasmid poorly secreted RNase into the medium, the plasmid pYE RNAP-Rh was constructed, in which the signal sequence of RNase Rh was replaced by the prepro-sequence of aspartic proteinase-I, one of the extracellular enzymes secreted by R. niveus. Yeast cells harboring pYE RNAP-Rh produced RNase efficiently (ca. 40 micrograms/ml) into the medium. The product was a mixture of six enzymes (RNase RNAP-Rhs) having 3, 5, 9, 13, 14, and 16 additional amino acid residues attached to the amino terminus of the mature RNase Rh. The major product was the RNase with three additional amino acids at the amino terminus. Limited digestion of RNase RNAP-Rhs with staphylococcal V8 protease succeeded in shortening the various lengths of extra amino acid residues attached to the amino terminus of RNase Rh, yielding an RNase that has 3 additional amino acids at the amino terminus. It has been named RNase RNAP-Rh. The RNase RNAP-Rh showed the same specific activity and CD spectra as those of RNase Rh, suggesting that the two have similar conformations to each other around aromatic amino acid residues and the peptide backbone.

Amino Acid Sequence↗

PubMed1991

Molecular cloning of a Pseudomonas paucimobilis gene encoding a 17-kilodalton polypeptide that eliminates HCl molecules from gamma-hexachlorocyclohexane.

Pseudomonas paucimobilis UT26 is capable of growing on gamma-hexachlorocyclohexane (gamma-HCH). A genomic library of P. paucimobilis UT26 was constructed in Pseudomonas putida by using the broad-host-range cosmid vector pKS13. After 2,300 clones were screened by gas chromatography, 3 clones showing gamma-HCH degradation were detected. A 5-kb fragment from one of the cosmid clones was subcloned into pUC118, and subsequent deletion and gas chromatography-mass spectrometry analyses revealed that a fragment of ca. 500 bp was responsible for the conversion of gamma-HCH to 1,2,4-trichlorobenzene via gamma-pentachlorocyclohexene. Nucleotide sequence analysis revealed an open reading frame (linA) of 465 bp within the fragment. The nucleotide sequence of the linA gene and the deduced amino acid sequence showed no similarity to any known sequences. The product of the linA gene was 16.5 kDa according to sodium dodecyl sulfate-polyacrylamide gel electrophoresis.

Amino Acid Sequence↗

PubMed1991

Influence of sympathetic nerve activity on ventricular arrhythmogenicity in the dog with chronic hypokalemia.

To examine the influence of sympathetic nerve activity on ventricular arrhythmogenicity in the dog with chronic hypokalemia, an electrophysiologic study was performed before and after bilateral stellectomy (BS) in 10 dogs with chronic hypokalemia (2.8 +/- 0.1 mEq/L), which was created by feeding a low-potassium diet and by administering furosemide over a four-week period, and the results were compared with those obtained from 10 dogs with normokalemia (4.7 +/- 0.3 mEq/L) from being fed an ordinary diet over a four-week period. Before BS the incidence of electrically induced ventricular arrhythmias was higher in the hypokalemic than in the normokalemic dogs. After BS it was decreased considerably in the hypokalemic but not in the normokalemic dogs. Heterogeneity of effective refractory period (delta ERP), which was determined as the difference between the longest and shortest effective refractory periods in three sites of the right and left ventricles, was greater in the hypokalemic than in the normokalemic dogs before BS. The delta ERP decreased slightly in the two groups both before and after BS. There was, however, no significant difference in delta ERP in the two groups both before and after BS. Ventricular fibrillation threshold (VFT) was significantly lower in the hypokalemic dogs than in the normokalemic dogs before BS (p less than 0.005). VFT was elevated in the two groups after BS. Percent increase in VFT after BS was significantly greater in the hypokalemic than in the normokalemic dogs. In conclusion, sympathetic nerve activity may play an important role in the increase in ventricular arrhythmogenicity in the presence of chronic hypokalemia.

Animals↗

PubMed1991

Quantification of cell nuclei isolated from hepatocytes by cell lysis with nonionic detergent in citric acid.

A method was developed for determining the number of nuclei of hepatocytes cultured on collagen gel using a nonionic detergent, Nikkol BO-10TX. The cells were recovered in a test tube after solubilizing the gel by incubating it with the detergent in 0.1 M citric acid and then centrifuging the mixture. Nuclei were isolated from the cells with the same detergent solution and collected by centrifugation. The numbers of nuclei in cultures, scored with a hemocytometer or an electronic particle counter, were proportional to the lactate dehydrogenase activities of the cells. This method was also applicable for scoring the number of nuclei of hepatocytes cultured on collagen-coated plastic.

Animals↗

PubMed1991

Effect of L-cysteine on plasma concentration and urinary excretion of 1-(tetrahydro-2-furanyl)-5-fluorouracil metabolites.

Effects of L-cysteine (CySH) on the plasma concentrations and the urinary excretion of 1-(tetrahydro-2-furanyl)-5-fluorouracil (FT) and its metabolites were studied by high performance liquid chromatography in rats. Significantly higher plasma concentrations of FT, 5-fluorouracil (5-FU) and cis-4'-OH-FT were obtained after an oral administration of FT (500 mg/kg) combined orally with CySH (500 mg/kg) when compared to FT alone. The urinary excretions of 5-FU, trans-3'-OH-FT, cis-4'-OH-FT, trans-4'-OH-FT and 4',5'-dehydro-FT significantly decreased up to 12 h but that of alpha-fluoro-beta-alanine significantly increased up to 24 h by the combined administration of CySH. Furthermore, the plasma concentration of 5-FU significantly increased at 0.5 h and its urinary excretion significantly decreased up to 4 h after an intraperitoneal administration of 5-FU (10 mg/kg) combined orally with CySH (500 mg/kg) when compared to 5-FU alone. The urinary pH significantly changed to acidic and the urinary volume significantly increased by the combined administration of CySH, so it was thought that the reabsorption of 5-FU through renal tubules from urine could increase and the increment of the urinary excretion of alpha-fluoro-beta-alanine was caused by this. Then it was suggested that the increase of the plasma concentrations of 5-FU and cis-4'-OH-FT could be attributed to the decrease of their urinary excretions after an administration of FT combined with CySH when compared to FT alone.

Animals↗

PubMed1991

Effects of sympathetic and parasympathetic stimulation on the induction of atrial flutter in dogs with aseptic pericarditis.

To study the effects of sympathetic stimulation (SS) and vagal stimulation (VS) on the induction of atrial flutter (AF) and its cycle length, aseptic pericarditis was produced surgically in 17 adult mongrel dogs. Programmed atrial stimulation was used to induce AF and to determine the effective refractory periods (ERP) and maximum conduction delay (maxCD) of the atrium. These tests were performed before and during stimulation of the right cervical vagus nerve and the right stellate ganglion. Results showed: (1) AF could be induced in animals with short ERP and large maxCD before SS; (2) ERP was significantly shortened, maxCD was significantly increased by VS; (3) During SS, ERP was slightly shortened, but there were no changes in maxCD and the induction rate of AF; (4) The cycle length of AF was shortened by SS, however, the cycle length of AF was shortened more notably by VS than by SS. From these findings, a shortening of the ERP and an increase in maxCD appear to be related to an increased AF induction rate by VS.

Animals↗

PubMed1991

Isolation and sequencing of a gene, C-ADE1, and its use for a host-vector system in Candida maltosa with two genetic markers.

The host-vector systems of an n-alkane-assimilating-yeast, Candida maltosa, that we previously constructed consisted of a vector replicating with an ARS region of this yeast, and C. maltosa strains J288 (leu2) or CH1 (his5) as hosts. Since each of these hosts has a single genetic marker, we have developed a new host-vector system using two genetic markers. By UV irradiation of strain CH1, an adenine auxotrophic mutant, CHA1, forming red colonies was isolated. A DNA fragment complementing this deficiency was isolated from the C. maltosa genome. Since the DNA fragment also complemented the ade1 mutation of S. cerevisiae, we termed a gene contained in this DNA fragment C-ADE1. The nucleotides of C-ADE1 were sequenced. The deduced amino acid sequence (291 residues) had 65.6% homology with that of ADE1 of S. cerevisiae (306 residues). Having the cloned C-ADE1 DNA, we improved the host-vector system of C. maltosa.

Adenine↗

PubMed1991

Evidence that more than one gene encodes n-alkane-inducible cytochrome P-450s in Candida maltosa, found by two-step gene disruption.

An n-alkane-assimilating yeast, Candida maltosa, has a diploid genome. Probed with the previously isolated gene of n-alkane-inducible cytochrome P-450 (P-450alk), its allelic gene had been isolated, its nucleotides sequenced, and the interallelic divergence examined. Using one of the allelic genes, we disrupted the two alleles of the cytochrome P-450alk gene by a two-step gene disruption system. Surprisingly, the disruptant still assimilated n-alkane and contained n-alkane-inducible cytochrome P-450. This result indicates that, other than the disrupted two alleles, there is at least one other gene that encodes an n-alkane-inducible cytochrome P-450.

Alkanes↗

PubMed1991

Intensive individualized induction therapy with behenoyl cytarabine, daunorubicin and 6-mercaptopurine followed by intensive consolidation including intermediate-dose continuous cytarabine, mitoxantron, etoposide and vinca alkaloids in acute myeloid leukemia in adults.

Forty-one consecutive adult patients with acute myeloid leukemia (AML) were treated with an intensive individualized induction therapy of behenoyl cytarabine, daunorubicin, and 6-mercaptopurine, 29 patients (71%) achieved complete remission (CR). Patients then received three courses of intensive consolidation therapy, including intermediate-dose continuous cytarabine (400 mg/m2, for 5 days) and non-cross resistant drugs such as mitoxantron, etoposide and vincristine. During the course of the consolidation therapy, three patients died of infections and one died of myocardial infarction. Four patients underwent allogeneic bone marrow transplantation. The patients then received six courses of moderately intensive maintenance therapy for 1 year. The predicted 5-year continuing CR and disease-free survival rates of the CR patients were 62% (95% confidence limit, 41% to 83%) and 53% (33% to 73%), respectively. Although the number of patients in this study is small, the present study indicated that it may be possible to cure a fairly large proportion of AML patients by chemotherapy alone, if intensive induction therapy is followed by intensive consolidation therapy.

Acute Disease↗

PubMed1991

Immune mechanism facilitating clearance of Trypanosoma gambiense by IgG3 antibody from infected host.

The aggregation of trypansomes, immune adherence to macrophage and protection against infection of Trypanosoma gambiense are associated with IgG3 antibody. IgG3-mediated clumping trypanosomes are readily dissociated by the aid of complement to become free. Dissociation of the clumped trypanosomes in the equivalence area released approximately fifty percent of previous bound surface antigens. These antigens were capable of binding again to new IgG3 antibody. Experiments indicated that complement deposition altered functionally bivalent IgG3 antibody in the immune complex into a univalent one. Such event in the presence of complement is of great advantage to the infected host in killing pathogens in vivo, as it allows more antibodies to attach to surface antigens and subsequently initiate complement activity.

Animals↗

PubMed1991

[Cardiac rehabilitation in patients with acute myocardial infarction: assessments with T1-201 myocardial scintigraphy].

The effects of exercise training on myocardial perfusion during the first 3 months after acute myocardial infarction (AMI) were assessed by exercise myocardial scintigraphy and fibrinolytic examinations. Symptom-limited treadmill exercise with thallium-201 myocardial single photon emission CT (SPECT) and fibrinolytic examinations (tissue plasminogen activator antigen: tPA, plasminogen activator inhibitor-1 antigen : PAI-1) were performed 2 and 14 weeks after AMI in 13 patients with exercise training and in 12 patients without exercise training. For quantitative analysis, counts of region of interest in the infarct area and normal reference area were calculated on a polar map obtained from myocardial SPECT. Severity of the hypoperfused myocardium was determined as an initial percent uptake (%IU) and a delayed percent uptake (%DU). The difference (%DU-%IU) was defined as a parameter of residual ischemia in the infarct area (%redistribution : %RD). Total treadmill exercise duration according to the Bruce protocol increased significantly in the training group (351 +/- 89 to 431 +/- 118 sec, p < 0.01); whereas, there was no significant change in the non-training group (340 +/- 95 to 356 +/- 123 sec). In the training group the pressure-rate product and %DU increased significantly (225 +/- 55 to 259 +/- 58 mmHg.beats/min x 100, 59 +/- 19 to 65 +/- 20%, p < 0.01, respectively), and %RD decreased significantly (8.8 +/- 6.7 to 4.8 +/- 4.5%, p < 0.01), but there was no significant change in the non-training group (231 +/- 89 to 240 +/- 86 mmHg.beats/min x 100, 56 +/- 17 to 57 +/- 12% and 7.4 +/- 5.5 to 6.2 +/- 6.5%, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Circulation↗