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Biomedical subjects

K Yazawa

Publications and source records attributed to K Yazawa.

At least 91 records · Page 5Linked to original sources
PubMed1997

Serotyping of Cryptococcus neoformans strains isolated from clinical specimens in Thailand and their susceptibility to various antifungal agents.

One hundred and thirty-nine strains of Cryptococcus neoformans were isolated in Thailand from clinical specimens including 97 AIDS patients: 67 from Northern, 48 from Central, 17 from Northeastern and 7 from Southern regional hospitals. Six out of the 139 strains were serotype B and the remaining 133 were A. There was no correlation between serotypes and regional distribution. To our knowledge, this is the first report of serotyping studies on C. neoformans in Thailand. Studies on random amplified polymorphic DNA (RAPD) analysis showed that this method is useful for the differentiation of C. neoformans var. gattii (serotypes B and C) and C. neoformans var. neoformans (serotypes A and D). They also indicated that Thai isolates of C. neoformans var. gattii (serotype B) were a homogeneous group on the basis of their genotypes. Antifungal susceptibility tests using 5 antifungal agents including amphotericin B, fluconazole, flucytosine, itraconazole and micronazole against 50 selected strains of C. neoformans showed that they were sensitive to all of the antifungal agents tested except for one strain that was resistant to flucytosine.

AIDS-Related Opportunistic Infections↗
PubMed1997

Inhibitory effects of docosahexaenoic acid on colon carcinoma 26 metastasis to the lung.

Unsaturated fatty acids, including n-3 polyunsaturated fatty acids (PUFAs) such as docosahexaenoic acid (C22:6, DHA) and eicosapentaenoic acid (C20:5, EPA), and a series of n-6 PUFAs were investigated for their anti-tumour and antimetastatic effects in a subcutaneous (s.c.) implanted highly metastatic colon carcinoma 26 (Co 26Lu) model. EPA and DHA exerted significant inhibitory effects on tumour growth at the implantation site and significantly decreased the numbers of lung metastatic nodules. Oleic acid also significantly inhibited lung metastatic nodules. Treatment with arachidonic acid showed a tendency for reduction in colonization. However, treatment with high doses of fatty acids, especially linoleic acid, increased the numbers of lung metastatic nodules. DHA and EPA only inhibited lung colonizations when administered together with the tumour cells, suggesting that their incorporation is necessary for an influence to be exerted. Chromatography confirmed that contents of fatty acids in both tumour tissues and plasma were indeed affected by the treatments. Tumour cells pretreated with fatty acids in vivo, in particular DHA, also showed a low potential for lung colony formation when transferred to new hosts. Thus, DHA treatment exerted marked antimetastatic activity associated with pronounced change in the fatty acid component of tumour cells. The results indicate that uptake of DHA into tumour cells results in altered tumour cell membrane characteristics and a decreased ability to metastasize.

Animals↗
PubMed1997

Reduction in formation of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP)-induced aberrant crypt foci in the rat colon by docosahexaenoic acid (DHA).

Docosahexaenoic acid (DHA), a major component of fish oil, suppresses the formation and growth of aberrant crypt foci induced by 1,2-dimethylhydrazine and azoxymethane. In the present study we examined the effects of intragastric gavage administration of DHA on the yield of rat colonic aberrant crypt foci due to treatment with a heterocyclic amine, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), which induces colon cancer in male F344 rats and is considered to be a possible human colon carcinogen. Male F344 rats were given a standard diet (AIN-76A) and received 10 doses of PhIP (75 mg/kg body wt, by intragastric intubation, on days 1-5 and 8-12) with or without intragastric application of 1 ml DHA 4 h prior to each carcinogen treatment, followed by further DHA dosing. The numbers of PhIP-induced aberrant crypt foci per colon after 4 and 12 weeks DHA administration were significantly reduced to 47 and 38% respectively of the values obtained when PhIP alone was used. The mean number of aberrant crypts per focus was also decreased by DHA treatment. At week 4 the PhIP-DNA adduct levels in the colon of rats from the PhIP+DHA group were approximately two thirds of the PhIP group value. The results thus suggest that DHA exerts a preventive effect on PhIP-induced colon carcinogenesis.

Animals↗
PubMed1997

Suppression of azoxymethane-induced rat colon carcinoma development by a fish oil component, docosahexaenoic acid (DHA).

The effects of intragastric gavage administration of docosahexaenoic acid (DNA) , a major component of fish oil, on azoxymethane (AOM)-induced colon carcinogenesis in rats was investigated. Male F344 rats were treated with 15 mg/kg body wt of AOM once a week, for two weeks. The animals were given either 1 ml of DHA or water intragastrically 5 times a week, starting the day before the first carcinogen treatment. The numbers of AOM-induced aberrant crypt foci in the rats given DHA were 76% and 62% of the control values, at 4 and 12 weeks, respectively. After 36 weeks of DHA treatment, colon tumors were counted and examined histologically. The blood plasma levels of prostaglandin E2 (PGE2) and polyunsaturated fatty acids were also quantified. The incidences of colon cancer did not differ, being 96% and 92% in the AOM and AOM+DHA groups, respectively. Colon cancer multiplicity was, however, significantly decreased by the DHA treatment; 3.65 +/- 2.18 in the AOM group and 2.41 +/- 1.58 in the AOM+DHA group (P <0.01). Notably, the numbers of moderately differentiated adenocarcinomas in the middle and distal colon in the DHA-treated group were lower than in the AOM group. The levels of PGE2 and arachidonic acid in the blood plasma of DHA-treated rats were also significantly lower than in the AOM group. These results suggest that DHA exerts its inhibitory effect on colon carcinogenesis by modulating lipid metabolism and inhibiting the arachidonic cascade.

Animals↗
PubMed1997

Fatty acid synthesis of an eicosapentaenoic acid-producing bacterium: de novo synthesis, chain elongation, and desaturation systems.

The fatty acid synthesis systems of a Shewanella sp., strain SCRC-2738, that produces a large amount of eicosapentaenoic acid were investigated. Two kinds of fatty acid synthesis system, de novo synthesis and chain elongation ones, were detected in the cytosol. The de novo synthesis system required an acyl carrier protein, and produced palmitoyl- and palmitoleoyl-acyl carrier proteins as final products. The chain elongation system also required an acyl carrier protein, and produced an acyl-acyl carrier protein as a product, using palmitoyl-, palmitoleoyl-, stearoyl-, and oleoyl-CoAs as primers but not eicosanoyl- or eicosenoyl-CoA. There were an anaerobic pathway and an aerobic desaturation one for the production of unsaturated fatty acids. Eicosapentaenoic acid seemed to be produced through the aerobic desaturation pathway and not through the anaerobic one, since the latter pathway produced n-7 type monoenoic fatty acids, which are different from eicosapentaenoic acid in the position of the double bond. The desaturase utilized an acyl-acyl carrier protein as a substrate, and this activity increased in the presence of ferredoxin and ferredoxin NADP+ reductase. Thus, Shewanella sp., strain SCRC-2738, has novel characteristics as to both fatty acid chain elongation and desaturation systems.

Acetyl Coenzyme A↗
PubMed1997

Oesophageal cancer associated with other primary cancers: a study of 31 patients.

The aim of this study was to investigate the characteristics of oesophageal cancer associated with other primary cancers and the survival rate after surgery for the patients with these cancers. Of 202 patients with oesophageal cancer treated in the Second Department of Surgery, Shinshu University School of Medicine between 1981 and 1995, 31 patients (15.3%) had oesophageal cancer associated with other primary cancers. Twenty-one synchronous and 10 metachronous associated cancers were found and 25 of them were resected. Early-stage oesophageal cancer was much more frequent in the associated cases than in the non-associated cases. The stomach was the most frequently associated organ. The numbers of cases with triple and quadruple cancers were three and one, respectively. Three of these cases had intervals of over 6 years between tumours. Three cases with other primary cancers which had intervals of over 7 years after oesophagectomy were found, and two were carcinomas of the reconstructed gastric tube. In the outcome after surgery for oesophageal cancer, there was no difference between the associated and the non-associated cases, and also no difference between the synchronous and metachronous associated cases. Regarding the five-year and 10-year survival rates after surgery for the first cancers, the synchronous cases had a poorer outcome than did the metachronous cases. In conclusion, oesophageal cancer with other primary cancers is not always rare, and its outcome is not poor compared with that of the non-associated cases. These patients may achieve survival by early detection of both lesions and positive treatment. It is important to consider the risk of other primary cancers after oesophagectomy, and the success of the reconstructed gastric tube should be followed by endoscopy.

Aged↗
PubMed1997

Brasilinolide A, a new macrolide antibiotic produced by Nocardia brasiliensis: producing strain, isolation and biological activity.

A new 32-membered macrolide antibiotic, brasilinolide A was isolated from the fermentation broth of Nocardia sp. IFM 0406. The producer was identified as Nocardia brasiliensis. The antibiotic was only active against Aspergillus niger, but not active against other fungi including yeasts as well as other filamentous like fungi and bacteria. Brasilinolide A exerted an immunosuppressive activity in the assay system of a mixed lymphocyte reaction (MLR).

Animals↗
PubMed1997

Brasiliquinones A, B and C, new benz[alpha]anthraquinone antibiotics from Nocardia brasiliensis. I. Producing strain, isolation and biological activities of the antibiotics.

New benz[alpha]anthraquinone antibiotics (brasiliquinones A, B and C) with an ethyl group at C-3 were isolated. The producer was identified as Nocardia brasiliensis. The antibiotics were active against Gram-positive bacteria including Mycobacterium sp., but not active against Gram-negative bacteria or fungi. They were also active against multiple drug-resistant P388/ADR tumor cells.

Animals↗
PubMed1997

Nocardicyclins A and B: new anthracycline antibiotics produced by Nocardia pseudobrasiliensis.

Nocardicyclins A (1) and B (2), new anthracycline antibiotics have been isolated from the mycelial cake of Nocardia pseudobrasiliensis IFM 0624 (JCM 9894). The molecular formulae of 1 and 2 have been determined as C30H35NO11 and C32H37NO12, respectively, and the structures were characterized by 1- and 8-methoxyl groups, a 10-carbonyl group and a novel carbon-methylated aminosugar constituent. Nocardicyclin A (1) exerts cytotoxic activity against L1210 and P388 leukemia. Nocardicyclins A (1) and B (2) are active against Gram-positive bacteria including Mycobacterium spp. and Nocardia spp., but inactive against Gram-negative bacteria.

Anthracyclines↗
PubMed1997

[Renal cell carcinoma in a horseshoe kidney: a case report].

A 69-year-old man presented for further examination for left renal mass. Computed tomography and magnetic resonance imaging revealed a heterogenous mass on the left side of a horseshoe kidney accompanied with renal vein thrombus. Aortography showed a hypervascular mass in the left kidney and aberrant arteries to the isthmus originating from the aorta. A left nephrectomy with the division of the isthmus was performed through an abdominal transperitoneal approach. Histological evaluation revealed grade 2, stage T3b, renal cell carcinoma. The patient was free of tumor, but died of intracerebral hemorrhage 5 months after the operation.

Aged↗
PubMed1997

[Renal cell carcinoma associated with renal artery aneurysm].

We report the 5th case of renal cell carcinoma associated with renal artery aneurysm in the Japanese literature. A 57-year-old woman was admitted to our hospital for further examination of a right renal mass. Computerized tomography and magnetic resonance imaging revealed a 6 x 5 cm tumor at the upper pole of the right kidney and an aneurysm of the right renal artery. An angiography showed duplicated renal arteries and a saccular aneurysm 2.1 x 2.5 cm occurring at the first bifurcation of one renal artery. A transperitoneal radical nephrectomy was performed.

Aneurysm↗
PubMed1997

[Acute necrotizing encephalopathy with horizontal gaze palsy].

Acute necrotizing encephalopathy (ANE) of childhood is a newly proposed disease entity characterized by symmetrically distributed necrotic brain lesions in the thalamus, cerebral white matter, brainstem, and cerebellum. We report a 4-year-old girl with severe psychomotor delay and horizontal gaze palsy as sequelae of ANE at 17 months of age. The computed tomography showed bilaterally symmetrical low density areas in the thalamus and low density areas in the left middle cerebral artery (MCA) region and the posterior cerebral artery (PCA) region. MRI (T 1-weighted) revealed unevenly distributed small low signal intensity areas with scattered high intensity regions in the thalamus bilaterally. The T2-weighted images showed multiple small low intensity areas around high intensity areas, and low signal intensity areas in the left middle cerebral artery (MCA) region and the posterior cerebral artery (PCA) region. In addition to severe psychomotor delay, the patient exhibited a peculiar eye movements. Horizontal ocular movement was impaired, but vertical ocular movement was almost completely normal. As clearly shown by MRI of the brain, the pontine tegmentum, including bilateral abducens nucleus, paramedian pontine reticular formation (PPRF), medial longitudinal fasciculus (MLF), and the facial nerve were affected, but the thalamo-mesencephalic junction, including the rostral interstitial medial longitudinal fasciculus (riMLF) and the nucleus of Cajal, was spared. To our knowledge, this is the first case of ANE associated with this selective ocular movement disorder ever reported. Because of the multiple symmetrical lesions and pons and the asymmetrical lesions of the MCA and PCA regions in the present case, occlusion of a single vessel could not account for the pathology. The pathophysiological mechanism of ANE is unknown. We postulate that some toxic or vasoactive agent caused vasospasm and subsequent breakdown of the blood-brain barrier, especially in the thalamus and pons, resulting in the unique distribution of the lesions and the rare eye movement disorder observed in the present case.

Brain↗
PubMed1997

[A case of locally advanced squamous cell carcinoma in bladder diverticulum successfully treated by bladder-preserving therapy].

A 62-year-old man visited our hospital with asymptomatic gross hematuria. On cystoscopy, two diverticula were identified at the dome of the urinary bladder and one of them was packed with a tumor. Biopsy showed squamous cell carcinoma (SCC), G1, but malignancy was not detected in the rest of the vesical mucosa. We selected bladder-preserving therapy. Pathological diagnosis after partial cystectomy was SCC, G1 > G2, pT3b. Postoperatively, 3 courses of adjuvant chemotherapy with methotrexate, bleomycin and cisplatin were performed. The patient has remained free of recurrence for 4.5 years.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1997

[A case of a successfully treated subclavian aneurysm complicated by a brachiocephalic aneurysm, and the left vertebral artery occlusion].

The patient was a 67-year-old male. Preoperative DSA study revealed a right subclavian aneurysm, a brachiocephalic aneurysm, stenosis of the left common carotid artery and the left subclavian artery, and occlusion of the left vertebral artery. An intraoperative occlusion test of the right vertebral artery showed a decline of the brainstem auditory evoked responses (BAER) seven minutes after the start of the procedure. Cardiopulmonary bypass was established by femoral arterial and bicaval cannulation. Under selective cerebral perfusion by cannulation of both common caroid arteries, a partial aortic arch replacement was performed using a graft patch with 3 branches. These three branches were connected to the right subclavian artery and to both common carotid arteries, respectively. Under deep hypothermia the right vertebral artery was reconstructed with the saphenous vein graft. Proximal anastomosis between the saphenous vein graft and the right caroid graft was done perfusion from a branch of the saphenous vein graft in order to shorten ischemic time of basilar arterial region. The patient was weaned from bypass without problems. After weaning the BAER test was again performed and found to be normal. The postoperative course was uneventful. Postoperative DSA examination showed good blood flow in all the reconstructed vessels. This study suggests that deep hypothermia and shortening of ischemic time of the basilar arterial region are effective in preventing ischemic injury of the brain stem and the cerebellum.

Aged↗
PubMed1996

Characterization of human cardiac Na+ channel mutations in the congenital long QT syndrome.

The congenital long QT syndrome (LQTS) is an inherited disorder characterized by a prolonged cardiac action potential. This delay in cellular repolarization can lead to potentially fatal arrhythmias. One form of LQTS (LQT3) has been linked to the human cardiac voltage-gated sodium channel gene (SCN5A). Three distinct mutations have been identified in the sodium channel gene. The biophysical and functional characteristics of each of these mutant channels were determined by heterologous expression of a recombinant human heart sodium channel in a mammalian cell line. Each mutation caused a sustained, non-inactivating sodium current amounting to a few percent of the peak inward sodium current, observable during long (> 50 msec) depolarizations. The voltage dependence and rate of inactivation were altered, and the rate of recovery from inactivation was changed compared with wild-type channels. These mutations in diverse regions of the ion channel protein, all produced a common defect in channel gating that can cause the long QT phenotype. The sustained inward current caused by these mutations will prolong the action potential. Furthermore, they may create conditions that promote arrhythmias due to prolonged depolarization and the altered recovery from inactivation. These results provide insights for successful intervention in the disease.

Animals↗