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Biomedical subjects

K Shimada

Publications and source records attributed to K Shimada.

At least 379 records · Page 21Linked to original sources
PubMed1999

[Indication and outcome in emergent coronary artery bypass graft for acute coronary syndrome].

Among 462 cases receiving coronary artery bypass graft (CABG) during the period from November 1991 to January 1999, emergency operation was performed within 24 hours for 27 cases. Male-to-female ratio was 21:6, and age of patients ranged from 50 to 83 years (average age: 65.9 years). Intra aortic balloon pumping (IABP) was used from preoperative period for 25 cases, and PCPS was used for one case. Operation was performed under cardiac arrest in 25 cases and under ventricular fibrillation in 2. Average number of grafts was 2.4 +/- 1.0 and perioperative mortality was 25.9%. The results of emergency cases were extremely low compared with mortality of palliative operation of 3.4%, whereas mortality has been improved to 12.5% (2/16) in the last two years. These results suggest that it is important for the improvement of the outcome in emergency CABG to prevent aggravation of circulatory dynamics and to shift to operation under stable conditions.

Aged↗
PubMed1999

[A case of thoracoscopic resection of a pulmonary infarction mimicking a metastatic lung tumor].

We report here a rare case of pulmonary infarction which was resected as a metastatic pulmonary tumor. A 57-year-old male patient referred for exhibiting an abnormal shadow on chest X-ray 8 months after the resection of invasive adrenal tumor. The patient underwent thoracoscopic resection of the lesion as a metastatic tumor. However, intraoperative pathological examination revealed that the resected specimen was pulmonary infarction. Post-operative MRI and ultrasound images showed no evidence of venous thrombus. Pulmonary infarction can exhibit an abnormal shadow in the lung fields, and it is necessary to be distinguished from true tumor.

Diagnosis, Differential↗
PubMed1999

[A case report of double roentgenographically occult lung cancer revealed by postsurgical pathological study].

A 66-year-old man admitted to our hospital as a roentgenographically occult lung cancer (ROLC) detected by sputum cytology of class IV. A differential brushing of all branches of the bronchi was performed and squamous cell carcinoma was detected only from the right B8 segmental bronchus. Right lower lobectomy was performed and the microscopic findings of surgical specimen revealed the squamous cell carcinomas were seen at not only B8 bronchus but also B7 bronchus. The frequency of multicentricity of ROLC is reported to be high, and a differential bronchial brushing of all bronchi is a very powerful method to diagnose synchronous multiple lung cancer. However, we failed to detect a cancer lesion of B7 segmental bronchus in this case. Since, the outcomes of surgical treatments for either synchronous or metachronous multiple primary lung cancer are satisfactory, limited surgical treatments might be appropriate as an initial treatment for a ROLC.

Aged↗
PubMed1999

[The structural polymorphism in D8S580-STR region].

The STR structure of the D8S580 locus was analyzed by the base sequencing technique. Alleles were collected separately by urea denaturing polyacrylamide gel electrophoresis of the PCR amplification product, followed by cutting of the target DNA band from the gel, and reamplification. As a result, this locus was shown to have a complex STR structure consisting of four types of repeat units, i.e. GGAA (II), GAAA (III), GAAAA (IV), and GCAA (V). Of 53 unrelated Japanese individuals, 51 were heterozygous, and the most frequent allele was type IV 8-II 7 III 6 III 3 (16%). Forty-four alleles with distinct structures appeared once the samples tested. As 57 different alleles were detected in this study, this region is considered to be one of the locus that have a high degree of repetitive structural polymorphism and therefore useful in forensic science.

Humans↗
PubMed1999

[Association between chlamydial infection and coronary artery disease].

Recent epidemiological studies have demonstrated the association between Chlamydia pneumoniae infection and coronary atherosclerosis. However, the relationship is less clear in the Japanese population. Serum IgA and IgG antibodies to Chlamydia-specific lipopolysaccharide were measured by enzyme-linked immunosorbent assay in 152 consecutive patients(112 males, 40 females, mean age 57 years)who underwent coronary angiography. Patients(n = 123)with coronary artery disease(CAD)were defined as having more than 50% diameter stenosis in at least one major coronary artery. The control group(n = 29) had normal coronary angiograms. In the CAD group, there was a high tendency of prevalence of IgA(20% vs 7%, p = 0.08)and IgG(54% vs 34%, p = 0.052). Prevalence of either IgA or IgG was significantly higher (59% vs 38%, p = 0.045) compared with the control group. Although the index of IgA antibody was not significantly different between the CAD and control groups(median 0.52 vs 0.36, p = 0.19), the index of IgG antibody was significantly higher in the CAD group than in the control group(median 1.29 vs 0.82, p = 0.026). The odds ratios for CAD were 3.4[95% confidence interval(CI)0.6-18.7]for the prevalence of IgA, 2.3(95% CI 0.9-5.2)for the prevalence of IgG, and 2.3(95% CI 1.0-5.2)for the prevalence of either IgA or IgG. Patients with CAD tended to have high prevalence of antibodies to Chlamydia spp, and these findings suggest an association between chlamydial infection and coronary atherosclerosis in the Japanese population.

Antibodies, Bacterial↗
PubMed1999

Adjuvant therapy for gastric carcinoma: closing out the century.

Gastric cancer is often advanced and unresectable at diagnosis. Even when a curative resection is possible, the 5-year survival rate for patients with T2 or higher tumors is less than 50%. Survival rates are even lower if lymph node metastases are present at surgery. Many phase III trials of adjuvant therapy have been conducted around the world during the past 4 decades, but their interpretation varies in the East and West. In the West, postoperative treatment modalities have not proven to be superior to postsurgical observation alone. Thus, at present, the routine use of postoperative therapy should be discouraged. In the Orient, however, routine use of postoperative chemotherapy and/or immunotherapy is common after a surgical procedure. Further investigations that correlate treatment response with molecular markers are needed. Improved clinical trial designs, including better preoperative staging, standardized surgical techniques, inclusion of adequate numbers of patients, and the continued use of a surgery-alone control group, are essential. In addition, the incorporation of newer active agents, radiotherapy, and new strategies, such as preoperative therapy and selection of patients based on tumor biology, would result in much-needed advances. Less toxic approaches with novel mechanisms of action, such as antiangiogenesis therapy, tumor vaccines, monoclonal antibodies, and matrix metalloproteinase inhibitors, also hold promise.

Antineoplastic Agents↗
PubMed1999

[Recent advanced knowledges related with lipoprotein metabolism].

This article aims to highlight recent advanced knowledges in enzymes and transfer protein in lipoprotein metabolism, including lipoprotein lipase (LPL), hepatic triglyceride lipase (HTGL), lecithin: cholesterol acyltransferase (LCAT) and cholesteryl ester transfer protein (CETP). In addition to its traditional role in the hydrolysis of lipoproteins, recent studies have revealed other functions of LPL and HTGL which may serve as ligands of cell surface receptors and/or proteoglycans. Clinical studies also have demonstrated new aspects in genetic polymorphism of both enzymes related with coronary artery disease. Several animal models have provided exact functions of LCAT and CETP which play an important role of reverse cholesterol transport. Clinical approach of CETP deficiency may be useful to identify the mechanism of atherosclerosis.

Carrier Proteins↗
PubMed1998

Nicotine inhibits the production of inflammatory mediators in U937 cells through modulation of nuclear factor-kappaB activation.

Cigarette smoke is a major risk factor for lung cancer and respiratory infections. This increased susceptibility may result from cigarette smoke-induced impairment of the immune system. In this study, we evaluated the effect of nicotine on the production of inflammatory mediators by activated macrophages. Pretreatment with nicotine caused a significant inhibition of LPS-induced IL-1, IL-8, and PGE2 expression at the transcriptional level in U937 cells. Nicotine inhibited the activation of a transcription factor, NF-kappaB, which in turn, binds to and mediates transcriptional activation of these genes. These inhibitory effects of nicotine may contribute to cigarette smoke-induced immunosuppression.

Cyclooxygenase 2↗
PubMed1998

Biologically active oligodeoxyribonucleotides. 5. 5'-End-substituted d(TGGGAG) possesses anti-human immunodeficiency virus type 1 activity by forming a G-quadruplex structure.

A series of hexadeoxyribonucleotides (6-mers), d(TGGGAG), substituted with a variety of aromatic groups at the 5'-end were synthesized and tested for anti-human immunodeficiency virus type 1 (HIV-1) activity. While unmodified d(TGGGAG) (31) had no anti-HIV-1 activity, compound 23 with a 3,4-di(benzyloxy)benzyl (DBB) group at the 5'-end potently inhibited the HIV-1IIIB-induced cytopathicity of MT-4 cells in vitro (IC50 = 0.37 microM) without cytotoxicity up to 40 microM. A thermal denaturation study on the 5'-end-substituted 6-mers by means of the circular dichroism (CD) spectra demonstrated that the aromatic substituent attached at the 5'-end of the 6-mer strongly enhanced the formation of a parallel helical structure consisting of four strands (quadruplex). On the contrary, compound 36, in which one of the guanosines of 23 was replaced by a thymidine, did not form a quadruplex, thus exhibiting no anti-HIV-1 activity. Moreover, both compound 15, with a tert-butyldiphenylsilyl group solely at its 3'-end, and compound 21, with a relatively small substituent, a benzyl group, at the 5'-end, formed quadruplexes but had no anti-HIV-1 activity. These findings led us to the conclusion that both the quadruplex structure and the aromatic substituent with adequate size at the 5'-end are crucial for the interaction of the 5'-end-substituted 6-mers with the V3 loop as well as the CD4 binding site on viral gp120, resulting in anti-HIV-1 activity.

Anti-HIV Agents↗
PubMed1998

Studies on neurosteroids. VII. Determination of pregnenolone and its 3-stearate in rat brains using high-performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry.

An assay method for pregnenolone and its 3-stearate in rat brains has been developed using LC-atmospheric pressure chemical ionization (APCI) isotope dilution MS. The extraction of the rat brain homogenate containing deuterated internal standards (ISs) with organic solvent followed by silica gel mini-column chromatography gave two fractions containing pregnenolone and its 3-stearate together with the respective IS. Each fraction was derivatized into 3-acetate-20-methyloxime and 20-methyloxime, respectively, followed by silica gel mini-column chromatography to remove the excess reagents, and then each derivatized fraction was applied onto reversed-phase LC-APCI-MS. The method was applied to the determination of these steroids in the gray matter and olfactory bulbs of rat brains, which were divided into control and acute stressed specimens. Although pregnenolone in both regions of the rat brains increased more than five times after stress, its 3-stearate decreased after stress.

Animals↗
PubMed1998

Cyclooxygenase 2 expression by endothelin-1-stimulated mouse resident peritoneal macrophages in vitro.

Macrophages have been shown to produce endothelin and to play a role in the pathogenesis of neural damage after cerebral ischemia or vasospasm after subarachnoid hemorrhage. Cyclooxygenase 2 is induced during inflammation following brain insult and participates in inflammation-mediated neurotoxicity. However, it has not yet been established how endothelin-1 acts on cyclooxygenase 2 expression in macrophages. In the present study, we examined the effects of endothelin-1 on cyclooxygenase 2 expression and prostaglandin E2 production, and the effects of endothelin ET(A) and ET(B) receptor antagonists. Stimulation by endothelin-1 ranging from 10(-11) to 10(-9) M time and dose dependently increased the production of prostaglandin E2 and the expression of cyclooxygenase 2 protein without changing that of cyclooxygenase 1 protein, an effect which was inhibited by dexamethasone, nonsteroidal anti-inflammatory drugs and the selective endothelin ET(B) receptor antagonist, BQ788 (N-cis-2,6-dimethylpiperidinocarbonyl-L-gamma-methyl-leucyl-D-L-me thoxycarbonyl-tryptophanyl-D-norleucine). The selective endothelin ET(A) receptor antagonist, BQ123 [cyclo (D-Trp-D-Asp-Pro-D-Val-Leu)] also inhibited these reactions, but its potency was less than that of the selective endothelin ET(B) receptor antagonist. Endothelin ET(A) and ET(B) receptor antagonists had no effects on cyclooxygenase 2 protein expression and prostaglandin E2 production in lipopolysaccharide-stimulated macrophages. We conclude that endothelin-1 increases cyclooxygenase 2 protein expression and prostaglandin E2 production via mainly endothelin ET(B) receptors and partly endothelin ET(A) receptors in macrophages; however, lipopolysaccharide increases both cyclooxygenase 2 protein expression and prostaglandin E2 production in pacrophages without involving endothelin ET(A) or ET(B) receptor-mediated processes.

Animals↗
PubMed1998

Interaction site for soluble cytochromes on the tetraheme cytochrome subunit bound to the bacterial photosynthetic reaction center mapped by site-directed mutagenesis.

The crystallographic structure of the Blastochloris (formerly called Rhodopseudomonas) viridis tetraheme cytochrome subunit bound to the photosynthetic reaction center (RC) suggests that all four hemes are located close enough to the surface of the protein to accept electrons from soluble cytochrome c2. To identify experimentally the site of this reaction we prepared site-directed mutants of Rubrivivax gelatinosus RCs with surface charge substitutions in the bound cytochrome subunit and studied the kinetics of their reduction by soluble cytochromes (mitochondrial horse cytochrome c, Blc. viridis cytochrome c2, and Rvi. gelatinosus cytochrome c8). In comparison with the wild-type, the mutants E79K (glutamate-79 substituted by lysine), E93K (glutamate-93 substituted by lysine), and E85K (glutamate-85 substituted by lysine) located near the solvent-exposed edge of low-potential heme 1, the fourth heme from the special pair of bacteriochlorophyll, exhibited decreased second-order rate constants for the reaction between the tetraheme subunit and the soluble cytochromes. Double charge substitutions in this region: E79K/E85K (glutamate-79 and -85 both replaced by lysine) and E93K/E85K (glutamate-93 and -85 both replaced by lysine) appeared to show an additive inhibitory effect. Mutations in other charged regions did not alter the kinetics of electron transfer between bound and soluble cytochromes. In light of the available structural information on Blc. viridis RC, these results indicate that the cluster of acidic residues immediately surrounding the distal heme 1 of the RC-bound tetraheme subunit forms an electrostatically favorable binding site for soluble cytochromes. Thus, all four hemes in the subunit seem to be directly involved in the electron transfer toward the photo-oxidized special pair of bacteriochlorophyll. On the basis of these findings, a model is proposed for the hypothetical cytochrome c2-RC transient complex for Blc. viridis.

Amino Acid Substitution↗
PubMed1998

Gene expression of steroidogenic enzymes in chicken embryonic gonads.

This paper reviews the molecular aspects of sex differentiation in birds and describes the sex-reversal effects of aromatase inhibitor on mRNA expression of steroidogenic enzymes. Although it is unknown whether the sex-determining gene resides in the W chromosome or whether a gene-dosage mechanism is involved in sex determination, it is clear that anti-Müllerian hormone (AMH) and androgen play a key role for testicular development, whereas estrogen is important for ovarian formation. Our in situ hybridization results demonstrated that mRNA expression of P450aromatase first takes place on day 6.5 of incubation exclusively in the female gonad. Treatment with aromatase inhibitor in ovo suppressed mRNA expression in genetic females. This suggests that ovarian development is promoted by aromatase expression via estrogen production. On the other hand, previous reports demonstrated that formation of the testis is accompanied by Sox9 and AMH mRNA expression, which start on days 6 and 8, respectively. This suggests that Sox9 plays an important role for the male determining pathway which leads to AMH expression and formation of the testis.

Animals↗