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Biomedical subjects

M Shirai

Publications and source records attributed to M Shirai.

At least 109 records · Page 6Linked to original sources
PubMed1997

A novel genetic organization: the leuA-rpoD1 locus in the cyanobacterium Microcystis aeruginosa K-81.

We cloned and sequenced the region upstream of rpoD1, which encodes a principal sigma factor in the cyanobacterium Microcystis aeruginosa K-81. An open reading frame (orf1, 1599 bp) was discovered, the deduced amino-acid sequence of which (533 aa, 58, 016 Da) exhibits homology to another bacterial leuA gene product, 2-isopropylmalate synthase. The leuA (orf1) gene specifically complemented an E. coli leuA mutant. The 5'-upstream region of leuA did not contain possible leader peptide or stem-loop structures for attenuation. These findings indicate that the genetic structure of the leuA-rpoD1 locus in M. aeruginosa K-81 significantly differs from those of known leuA and rpoD loci found in other bacteria.

Amino Acid Sequence↗
PubMed1997

An azoospermic male with an unbalanced autosomal-Y translocation.

An azoospermic male with an unbalanced translocation between the Y chromosome and chromosome 15 was examined in the present study. Testicular biopsy found only Sertoli cells only within the seminiferous tubules of the 35-year-old patient. Chromosome analysis, using the techniques of G and C banding and fluorescent in situ hybridization revealed an abnormal karyotype of 46,XY,der(15)t(Y;15)(q12;p11). Deoxyribonucleic acid (DNA) analysis confirmed the presence of the genes such as DAZ and YRRM1 which are known to control spermatogenesis. The cause of spermatogenetic dysfunction in this particular patient therefore.

Adult↗
PubMed1997

Histochemical and immunohistochemical study of human gastric carcinoma differentiation with special reference to supplementary role for endosonography in evaluating depth of invasion.

The aim of this study was to evaluate the usefulness of gastric and intestinal epithelial phenotypic expression of gastric cancer cells, shown by mucin histochemical staining (paradoxical concanavalin A, galactose oxidase Schiff [GOS] and sialidase-GOS) and immunohistochemical reactivity (pepsinogens, SH-9, and TKH-2), as an adjunct to the assessment of depth of invasion of gastric carcinomas by endosonography (ES). In 110 resected adenocarcinomas, the proportion of intestinal-type cells increased with progression, as assessed by depth of invasion. The coincidence rate for gastric and intestinal phenotypic expression in biopsied and resected specimens was 96.3%. The positive predictive value of assessment of depth of invasion by ES was 73%. A low positive predictive value (45%) was achieved with type II-3 cases (according to our classification). However, the predictive value improved to 68% when depth of invasion was evaluated as the submucosal layer or deeper in cases in which more than 10% of cancer cells were of intestinal-type, although statistical analysis showed no significant difference between these predictive values. The sensitivity of diagnosis of submucosal invasion by cell differentiation in the type II-3 cases was significantly higher than that for the other types (89.5% versus 59.1%; P = 0.037). Phenotypic expression in biopsied specimens of gastric carcinomas proved helpful for evaluating the depth of invasion of gastric carcinoma by ES.

Adenocarcinoma↗
PubMed1997

Evaluation of seminiferous tubule scores obtained through testicular biopsy examinations of nonobstructive azoospermic men.

OBJECTIVE: To evaluate the seminiferous tubules of nonobstructive azoospermic men, a modified version of the Johnsen score known as the seminiferous tubule score was used. DESIGN: Retrospective clinical study. SETTING: University-based urology center. PATIENTS: One hundred twenty-eight infertile men with nonobstructive azoospermia who underwent open testicular biopsy. INTERVENTION(S): Categorization as follows of various seminiferous tubule characteristics according to the modified seminiferous tubule score parameters: [1] a total absence of cells within the seminiferous tubule, [2] Sertoli cell only, [3] a few spermatogonia, [4] many spermatogonia, [5] a few primary spermatocytes, [6] many primary spermatocytes, [7] a few secondary spermatocytes, [8] many secondary spermatocytes, [9] a few round spermatids, [10] many round spermatids, [11] a few late spermatids and/or spermatozoa, and [12] many late spermatids and/or spermatozoa. MAIN OUTCOME MEASURE(S): Seminiferous tubule score. RESULT(S): In terms of maximum seminiferous tubule score, scores of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, and 12 corresponded with total patient numbers of 9, 90, 0, 0, 3, 10, 0, 0, 3, 1, 11, and 1, respectively. CONCLUSION(S): It was discovered that intracytoplasmic sperm injection (ICSI) of round spermatids could be performed in 3.1% of the patients in this study and that ICSI using late spermatids or spermatozoa could be performed in 9.4% of the patients in order to achieve fertilization.

Adult↗
PubMed1997

Construction of hairpin ribozymes with a three-way junction.

Hairpin ribozymes with high cleavage activities were designed. An extra sequence was introduced at the 3'-end of the hairpin ribozyme to increase the binding to the substrate RNA, as compared to the wild-type hairpin ribozyme. A three-way junction (TWJ) was formed between the newly designed ribozyme and the substrate RNA. The complex with a solid TWJ showed less RNA cleavage activity than the wild-type hairpin ribozyme. However, the ribozyme with a TWJ with five unpaired bases or propandiol phosphate linkers had higher cleavage activity than the parent ribozyme without the TWJ. When a cis-cleavage system, in which the 5'-end of the substrate RNA was conjugated to the 3'-end of the ribozyme, was employed, the complex with the TWJ containing unpaired bases was also cleaved faster than the complex with the solid TWJ. This suggested that these differences in the cleavage activities were derived from the confirmation, and this was proven by nondenaturing gel electrophoresis. The TWJ hairpin ribozyme containing unpaired bases is able to bind strongly with substrate RNAs and to cleave them efficiently. Since the three-way ribozyme presented here is more active than the wild-type ribozyme, this type of ribozyme can serve as a more efficient tool to control RNA activities in vitro and in vivo.

Base Sequence↗
PubMed1997

Vasodilator effects of adrenomedullin on small pulmonary arteries and veins in anaesthetized cats.

1. This study was conducted to determine adrenomedullin (AM) action sites in the pulmonary vascular bed and the relation between its vasodilator effects and vascular tone. Moreover, an examination was made into whether calcitonin gene-related peptide (CGRP) receptors mediate pulmonary vasodilatations induced by AM. To this end, we directly measured internal diameter (i.d.) changes in small pulmonary arteries and veins (100-1100 microns i.d.) by use of an X-ray television system on the in vivo cat lung. 2. Under control (resting vascular tone) conditions, AM injections into the left main pulmonary artery caused dose-related i.d. increases in both small arteries and veins. The mean i.d. increase of the 100-1100 microns arteries (4 +/- 1, 11 +/- 2, and 17 +/- 2% with 0.01, 0.1, and 1 nmol kg-1 AM, respectively) was significantly larger than that for the veins (1 +/- 1, 5 +/- 2, and 7 +/- 2% with 0.01, 0.1 and 1 nmol kg-1 AM, respectively) whatever the injected dose of AM. 3. When unilobar hypoxia (5% O2) had decreased the i.d. of the 100-1100 microns arteries and veins by 16 +/- 3 and 6 +/- 3%, respectively, AM (0.1 nmol kg-1) was able to induce significantly larger i.d. increases in the arteries (28 +/- 3%) and veins (11 +/- 3%) than those under control conditions. 4. The AM-induced i.d. response pattern in the serially connected pulmonary arteries was quite different from that induced by CGRP; AM caused a greater increase in smaller vessels (100-500 microns) than in larger vessels (500-1100 microns). In the case of CGRP, a greater increase was observed in the larger vessels. 5. CGRP8-37 (100 nmol kg-1, i.v., followed by a continuous infusion of 0.2 nmol kg-1 min-1) had no significant effect on the i.d. increase induced by AM (0.1 nmol kg-1) in any serial segments of the arteries and veins. 6. The results indicate that, in the cat, AM induces greater vasodilatation in small pulmonary arteries and lesser vasodilatation in small veins, the maximum dilatation being in the more peripheral arterial segment (100-500 microns). The vasodilator effect of AM was enhanced when vascular tone was elevated. The data suggest that the AM-induced pulmonary vasodilatation is not mediated by CGRP receptors but by its own specific receptor.

Adrenomedullin↗
PubMed1997

Sexual function and clinical features of patients with Klinefelter's syndrome with the chief complaint of male infertility.

In this report, we present the overall sexual function and clinical features of patients with Klinefelter's syndrome with the chief complaint of male infertility. The study consisted of 40 patients with a control group of 55 infertile non-azoospermic males with a normal 46,XY karyotype who visited the Reproduction Center of Toho University Hospital during the 5.5-year period between January 1991 and June 1996 with the chief complaint of male infertility. Among the 40 patients with Klinefelter's syndrome, 38 cases were pure 47,XXY, one case was 47,XXY with a pericentric inversion of chromosome 9 and one case was a mosaic of 46,XY/47,XXY(2:28). Thirty-nine of these 40 patients were azoospermic and one (47,XXY) had severe oligoasthenozoospermia. The sexual function of the patients was evaluated according to their responses to a preliminary questionnaire devised by our department. There was no significant difference in the frequency of sexual function disturbances between the patients with Klinefelter's syndrome and the control group (67.5% vs. 60.0%; chi 2 analysis; p = 0.454). The mean frequency of sexual intercourse per month in the patients with Klinefelter's syndrome was significantly higher than in the control group (4.4 +/- 2.8 vs 3.3 +/- 1.6: Welch's t-test, p < 0.05). A possible explanation for this variation may lie in the fact that many of these patients were diagnosed with azoospermia poor to the administration of the questionnaire and may have wished to continue to have relations as a couple.

Adult↗
PubMed1997

Structural abnormalities of autosomal chromosomes in the male partner do not influence fertilization and early development of embryos after intracytoplasmic sperm injection.

The objective of this study was to determine whether or not abnormalities in the autosomal structure of the male partner have any influence on fertilization and early embryo development after intracytoplasmic sperm injection (ICSI). Thirty-seven couples in whom the male partners were examined by the same andrologist were included in this study. Six couples (group I) in whom the male partner possessed autosomal structural abnormality underwent seven ICSI cycles. As a control group, 31 couples (group II) in which the male partner was karyotypically normal underwent 41 ICSI cycles. Although the normal fertilization rates seen in group I were significantly higher than those in group II (P < 0.05), there was no significant difference in the cleavage rates between the two groups. We did not perform the analysis of the female partner's chromosomes, but we surmise that structural autosomal abnormalities in the male partner do not adversely influence fertilization at ICSI and early development of embryos.

Adult↗
PubMed1997

Dicentric Y chromosome in an azoospermic male.

We describe a 28 year old male with a pseudodicentric Y chromosome who suffered from azoospermia attributed to maturation arrest of the primary spermatocyte, as diagnosed by testicular biopsy. Chromosome analysis, using G, Q and C banding techniques, revealed an abnormal karyotype of 45,X[7]/46,X,psu dic (Y)(pter-->q11.2::q11.2-->pter)[33]. Polymerase chain reaction (PCR) DNA analysis did not detect the absence of DAZ and RBM1 which are candidates for azoospermic factor (AZF) genes. Therefore, it is suggested that the maturation arrest of the primary spermatocyte in this patient was caused either by a pairing dysfunction between the X and Y chromosomes during meiosis or by deletions in the autosomal or the Y chromosomal spermatogenesis controlling genes, excluding DAZ and RBM1.

Adult↗
PubMed1997

Control of poly-beta-hydroxybutyrate synthase mediated by acetyl phosphate in cyanobacteria.

Poly-beta-hydroxybutyrate (PHB) synthesis in a cyanobacterium, Synechococcus sp. strain MA19, is controlled at the enzyme level and is dependent on the C/N balance in the culture medium. The control involves at least two enzymes. The first enzyme is PHB synthase. Little PHB synthase activity was detected in crude extracts from cells grown under nitrogen-sufficient conditions (MA19(+N)). The activity was detected exclusively in membrane fractions from nitrogen-deprived cells (MA19(-N)) under light but not dark conditions. The shift in the enzyme activity was insensitive to chloramphenicol, which suggests posttranslational activation. Acetyl phosphate activated PHB synthase in membrane fractions from MA19(+N). In vitro, the activation level of PHB synthase changed, depending on the concentration of acetyl phosphate. The second enzyme was phosphotransacetylase (EC 2.3.1.8), which catalyzes the conversion of acetyl coenzyme A (acetyl-CoA) to acetyl phosphate. The activity was detected in crude extracts from MA19(-N) but not in those from MA19(+N). The results suggested that intracellular acetyl phosphate concentration could be controlled, depending on C/N balance and intracellular acetyl-CoA concentration. Acetyl phosphate probably acts as a signal of C/N balance affecting PHB metabolism in MA19.

Acetyl Coenzyme A↗
PubMed1997

Effect of hypoxia on amniotic fluid erythropoietin levels in fetal rats.

Erythropoietin (EPO) levels in amniotic fluid and serum were measured in hypoxic (fraction of inspired oxygen, FiO2, 0.09) and posthypoxic (following a 24-hour period of hypoxia, FiO2 0.09) fetal rats on day 21 of gestation. Each of the study groups comprised 12-20 fetuses. Each of the control groups consisted of 21 or 22 fetuses. Fetal serum EPO levels at 3, 6, 9, 12, and 24 h of hypoxia were significantly higher than the control level. Amniotic fluid EPO levels at 9, 12, and 24 h of hypoxia were also significantly increased compared to the control level. Fetal serum EPO levels returned to baseline during the 12- to 48-hour period after hypoxia. During the 0- to 48-hour posthypoxic period, amniotic fluid EPO levels were significantly higher than the control level. These data demonstrate that rates of appearance and turnover of amniotic fluid EPO are different from those of fetal serum EPO.

Amniotic Fluid↗
PubMed1997

Cytogenetic survey of 1,007 infertile males.

The aim of this study was to investigate the influence of a chromosome abnormality on male infertility. The subjects consisted of 1,007 males with the chief complaint of infertility. Karyotyping was conducted mainly by G banding. Major chromosome abnormalities were observed in 62 patients (6.2%) in total and consisted of sex chromosome abnormalities were observed in 62 patients (6.2%) in total and consisted of sex chromosome abnormalities in 38 patients (3.8%) and autosomal chromosome abnormalities in 24 (2.4%). Among the patients with sex chromosome abnormalities, 28 cases were 47, XXY, 3 were 47,XYY, and 7 cases had a Y chromosome abnormality. Autosomal chromosome abnormalities comprised 10 cases of reciprocal translocation, 8 cases of Robertsonian translocation, 5 cases of inversion, and 1 case of ring chromosome. In patients with a sperm density < 5 x 10(6)/ml, a total motile sperm count < 1 x 10(6), a follicle-stimulating hormone value > or = 30.1 mIU/ml, a luteinizing hormone value > or = 8.9 mIU/ml, a testosterone value < or = 2.69 ng/ml, or an average testis volume < or = 8 ml, the incidence of major chromosome abnormalities was significantly higher. These findings suggest that patients who need microinsemination should undergo chromosome analysis. We should counsel patients about obtaining adequate information on each chromosome abnormality.

Adult↗
PubMed1997

Is diabetic neuropathy responsible for diabetic impotence?

It is well known that diabetes mellitus is accompanied by complications of sexual dysfunction and it is believed that diabetic neuropathy may cause impotence. In our study, we found that not all the patients who visited our center with the chief complaint of diabetic impotence were suffering from organic impotence, and diabetes mellitus per se served as a means of psychological stress in a substantial number of cases. Probably because no method has been available to provide precise information on the state of the penile-controlling nerves, we found that a larger number of patients than expected were suffering from a vascular disorder.

Algorithms↗
PubMed1997

Targeted disruption of the mouse homologue of the Drosophila polyhomeotic gene leads to altered anteroposterior patterning and neural crest defects.

The rae28 gene is a mouse homologue of the Drosophila polyhomeotic gene (Nomura, M., Takihara, Y. and Shimada, K. (1994) Differentiation 57, 39-50), which is a member of the Polycomb group (Pc-G) of genes (DeCamillis, M., Cheng, N., Pierre, D. and Brock, H.W. (1992) Genes Dev. 6, 223-232). The Pc-G genes are required for the correct expression of the Homeotic complex genes and segment specification during Drosophila embryogenesis and larval development. To study the role of the rae28 gene in mouse development, we generated rae28-deficient mice by gene targeting in embryonic stem cells. The rae28-/- homozygous mice exhibited perinatal lethality, posterior skeletal transformations and defects in neural crest-related tissues, including ocular abnormalities, cleft palate, parathyroid and thymic hypoplasia and cardiac anomalies. The anterior boundaries of Hoxa-3, a-4, a-5, b-3, b-4 and d-4 expression were shifted rostrally in the paraxial mesoderm of the rae28-/- homozygous embryos, and those of Hoxb-3 and b-4 expression were also similarly altered in the rhombomeres and/or pharyngeal arches. These altered Hox codes were presumed to be correlated with the posterior skeletal transformations and neural crest defects observed in the rae28-/- homozygous mice. These results indicate that the rae28 gene is involved in the regulation of Hox gene expression and segment specification during paraxial mesoderm and neural crest development.

Animals↗
PubMed1997

Effect of ethylene thiourea on cultured rat embryos in the presence of hepatic microsomal fraction.

To investigate whether teratogenicity of ethylene thiourea (ETU) is due to ETU per se or to its metabolites, rat embryos cultured in vitro were exposed to 10 and 30 micrograms/ml of ETU in the presence or absence of rat liver microsomal fraction (S9mix). In the absence of S9mix, the incidence of morphological abnormalities increased dose-dependently. In the presence of S9mix, abnormal morphogenesis was almost absent in all embryos. These findings suggest that teratogenicity of ETU is due to ETU per se.

Abnormalities, Drug-Induced↗
PubMed1997

Effects of fenthion, isoxathion, dichlorvos and propaphos on the serum cholinesterase isoenzyme patterns of dogs.

The serum cholinesterase (ChE) isoenzyme patterns consist of 5 bands for normal beagle dogs. We examined the ChE isoenzyme patterns and ChE activities of 4 groups, each of which consisted of 4 dogs, given the organophosphate (OP) compounds fenthion (P = S type), isoxathion (P = S type), dichlorvos (P = O type) or propaphos (P = O type) po at 220, 75, 120 or 90 mg/kg respectively. Blood samples were collected for 30 d after the OP administrations. ChE isoenzyme bands 4 and 5 were inhibited 12 h after fenthion and isoxathion administration; dichlorvos and propaphos produced suppression of main bands 4 and 5 20 min after administration. This change was effective to differentiate the type of OP administered (P = S and P = O), while the main ChE isoenzyme bands of dog serum reflected inhibition of serum ChE activity.

Animals↗
PubMed1997

[Clinicopathological features of interstitial pneumonia associated with amyopathic dermatomyositis].

We studied clinicopathological characteristics of interstitial pneumonia associated with amyopathic dermatomyositis. The subjects comprised two men and three women, and their mean age was 58.2 years. All subjects had cruptions specific for dermatomyositis, but had no signs of myositis. They all presented with acutely or subacutely developed coughing and dyspnea. Results of tests for anti-Jo-1 antibody were negative in all cases. Chest X-ray films showed infiltrations or streaky shadows, or both in the middle and lower lung fields. Analysis of bronchoalveolar lavage fluid revealed abnormally high percentages of lymphocytes and neutrophils. In one patients a specimen obtained by open lung biopsy showed homogeneous cell infiltrations in alveolar septa and regional alveolar damage. That patient was successfully treated with cyclosporin and corticosteroids in early phase of the disease. The other four patients received immunosuppressive agents after respiratory failure developed. All four died despite having received high-dose corticosteroid and immunosuppressive therapy. Examination of autopsy specimens showed diffuse alveolar damage.

Acute Disease↗