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Biomedical subjects

K Nishimura

Publications and source records attributed to K Nishimura.

At least 91 records · Page 5Linked to original sources
PubMed1998

Assessment of hair cell death using the dye extrusion method.

We examined the usefulness of the dye extrusion method for assessing cochlear hair cell death in guinea pigs. Unilateral temporal bones were incubated in sterile Dulbecco modified Eagle's medium for 1-6 h and then perfused with PBS/0.3% trypan blue to determine hair cell viability. Cells with nuclei stained with trypan blue were assumed to have died. The contralateral temporal bones of each animal were incubated with the same medium for 1-6 h and examined by transmission electron microscopy (TEM). This method revealed that hair cell viability under these conditions was maintained for at most 3 h. After incubation for more than 3 h, hair cell injury began and increased. After 6 h incubation, TEM revealed apoptotic death of outer hair cells. The results with this method agreed with the TEM findings. The dye extrusion method is simple, easy and useful for screening hair cell death in the cochlea under pathological conditions.

Animals↗
PubMed1998

Cleavage product from the NO donor NOC-5 and inner ear hair cell damage.

Nitric oxide (NO) is a neurotoxic gas which causes neuronal cell death. NO ototoxicity has also been reported, 1-Hydroxy-2-oxo-3-(3-aminopropyl)-3-isopropyl-1-triazene (NOC-5), NO donor, was used for studying NO. In this in vitro study, we examined whether NOC-5 and the cleavage products arising from it after production of No have ototoxic effects on the cochlea. The temporal bones of 55 guinea pigs were dissected and incubated in Dulbecco Modified Eagle's Medium (DMEM) with low glucose and 10% foetal bovine serum (FBS) perfused with various concentrations (100, 50, 10, 1 mM, 100 microM) of NOC-5 (pH 7.4) or the same concentrations of N-isopropyl 1-3 propanildiamine (R-NH2). Hair cell death was assessed using trypan blue staining. With NOC-5, percentages of outer hair cell death were 99.2, 98.0, 45.2, 40.5, and 20%, respectively, and percentages of inner hair cell death were 69.3, 70.2, 22.5. 11.1 and 0%, respectively. With R-NH2, percentages of outer hair cell death were 90.3, 81.1, 29.8, 21.0 and 19.3%, respectively, and percentages of inner hair cell death were 61.4, 48.1, 10.2, 5.4 and 0%, respectively. Ultramicroscopic examination showed that hair cell death was necrotic. Although NOC-5 is useful for study of NO, its cleavage products are also ototoxic.

Animals↗
PubMed1998

Induction of macrophage exudation in the inner ear by OK432 treatment.

OK432, a heat- and penicillin-treated lyophilized powder of a low virulent Su strain of Streptococcus pyogenes, was injected into the perilymphatic space of guinea pigs in order to determine the kinetics of exudation of inflammatory cells into the cochlea over a 7-day period. OK432 induced exudation of many neutrophils and Asialo GM1-positive cells into the scala tympani. The numbers of these cells peaked on the first day after OK432 treatment, and then gradually decreased. Four days after treatment very few of either of these types of cells were observed in the scala tympani. Asialo GM1-positive cells were confirmed to be activated macrophages. In ears treated with physiological saline or with the additive included in OK432 in control studies, no notable changes in the inner ear were recognized. These findings suggest that the inner ear can undergo induction of macrophage rapidly exudation by OK432 treatment as has previously been observed for other organs.

Animals↗
PubMed1998

Surgical treatment of cancer extending from the retromolar fossa to the masticator space.

Cancer extending from the retromolar fossa to the masticator space with neck metastasis (T4N2M0, Stage IV) was surgically removed en bloc by maxillectomy using a mandibular swing technique. This approach allowed a wide surgical view and was useful as handling the external and internal pterygoid muscles and upper neck dissection could be combined. Though there have been several surgical approaches to the masticator space, in the case of tumors which are commonly malignant there, this approach is useful and satisfactory.

Carcinoma, Squamous Cell↗
PubMed1998

Apoptotic cell death in Kikuchi's disease: a TEM study.

The pathogenesis of Kikuchi's disease (Kikuchi-Fujimoto disease, histiocytic necrotizing lymphadenitis) remains unclear. However, some previous studies have suggested that a disorder in cellular immunity is responsible for this disease, and apoptotic cell death appears to be the principal finding in the histogenesis of this disease. In the present study, a lymph node from a female patient with Kikuchi's disease was examined by transmission electron microscopy (TEM). TEM revealed specific morphological features of apoptotic cells, such as nuclear chromatin condensation and fragmentation along the nuclear membrane with intact organelles, and the presence of histiocytes phagocytosing karyorrhectic debris (apoptotic bodies) in areas affected by Kikuchi's disease. Although neither the role nor the trigger of apoptosis in Kikuchi's disease has been clearly determined, our findings show that apoptotic cell death clearly plays a role in the pathogenesis of Kikuchi's disease.

Adult↗
PubMed1998

[Primary adenocarcinoma of the renal pelvis in a young male: a case report].

The patient was a 16-year-old male who visited our hospital with the chief complaint of microhematuria. Computed tomography revealed left hydronephrosis, renal stones and left renal tumor. Needle biopsy was performed under ultrasonography. The histological diagnosis was adenocarcinoma and left radical nephrectomy was performed. The histological diagnosis was mucinous adenocarcinoma of the renal pelvis. Postoperative chemotherapy was not given. The patient has had neither recurrence nor metastasis for 1 year following surgery. This is the 92nd reported case in the literature.

Adenocarcinoma↗
PubMed1997

Iterated Prisoner's Dilemma: pay-off variance.

The iterated Prisoner's Dilemma (IPD) is usually analysed by evaluating arithmetic mean pay-offs in an ESS analysis. We consider several points that the standard argument does not address. Finite population size and finite numbers of matches in the IPD game lead us to consider both pay-off variance and the sampling process in the evolutionary game. We provide a general form for the pay-off variance of the Markov strategist in the IPD game, and present a general analysis of the initial invasion process of an "all defection strategist" (ALLD) into a "tit-for-tat" (TFT) strategist population by considering stochastic processes. Finite population size, strategic error an the variances of pay-offs alter the prediction concerning the initial invasion of ALLD compared with the standard Evolutionarily Stable Strategy (ESS) analysis. Even though TFT gets the larger arithmetic mean, the variance of its pay-off is also larger when the expected iterations of the game are sufficiently large. Therefore, the boundary of the parameter of the probability of game continuity, w, above which ALLD does not have advantage to invade into the TFT population, becomes a bit larger than predicted by the deterministic model.

Biological Evolution↗
PubMed1997

Loss of imprinting of the insulin-like growth factor II gene in renal cell carcinoma.

Loss of imprinting (LOI) has been implicated in the pathogenesis of embryonal malignancies as well as adult cancers. Insulin-like growth factor II (IGF2) gene is an imprinted gene, normally transcribed only from the paternal allele. We investigated allele-specific expression of the IGF2 gene in 22 cases of renal cell carcinoma (RCC), a common adult-onset renal tumor. Sixteen cases (72%) were informative for IGF2 gene expression, and 9 (56%) of these cases showed biallelic expression of the IGF2 gene. Additionally, in four cases with biallelic expression from which uninvolved kidney tissue was available, LOI of the IGF2 gene was also demonstrated in the normal tissue. All cases with LOI of IGF2 were low-grade and low-stage tumors. LOI of the IGF2 gene in RCC was not associated with overexpression of IGF2 mRNA, whereas IGF2 overexpression was frequently observed in high-stage tumors. These results suggest that LOI of IGF2 predisposes to low-grade and low-stage tumors, whereas IGF2 overexpression may have a role in RCC tumor progression.

Adult↗
PubMed1997

Magnetic resonance imaging of skeletal muscles in the polymyositis.

Magnetic resonance imaging of skeletal muscles was performed in 11 patients with polymyositis. Two types of muscle lesions were revealed. The first, inflammation, showed increased signal intensity on T2-weighted images and iso-intensity on T1-weighted images. The second, fatty replacement, showed increased signal intensity on both images. The coronal sections could elucidate the extension of the lesion in each affected muscle. Inflammation was relatively diffuse, while homogeneous fatty replacement tended to begin at the lower myotendinous junctions.

Adipose Tissue↗
PubMed1997

Current views on geographic distribution and modes of infection of neurohelminthic diseases.

Neurohelminthiases are more prevalent in geographic areas where environmental factors and poor sanitary conditions favor the parasitism between man and animals. In recent years, population shifts and rapid transport have facilitated the spread of certain helminthic diseases from endemic to non-endemic areas. Although many helminthic parasites are known to cause various human diseases afflicting many millions of people in the world, neurohelminthiases are often not diagnosed because they have been unrecognized by clinicians or confirmatory diagnostic tests are not easily available. Paragonimiasis and schistosomiasis (fluke diseases) are endemic in Asia, Africa and Central America; lesions in the central nervous system (CNS) due to ectopic parasitism of the preadult and adult flukes produce various clinical features that often mimic other diseases. In most cestodiasis (tapeworm disease), the adult worm that lodges in the alimentary tract does not involve the CNS; however, the larvae often enter the nervous system by migration or by metastasis via the systemic circulation, where they cause cystic lesions. Cysticercosis is the most common CNS helminthic infection especially in endemic areas where the parasitism between man and pigs is maintained. In other cestodiases, infections to man are often caused by ingestion of food or water contaminated with feces of the definitive hosts (mammals or man). Nematodes (roundworms) generally enter the CNS by ectopic migration of the infective larvae (larva migrans); the routes of infection to man vary with species of the nematodes, and the animal hosts they infest. Angiostrongylus cantonensis is a neurotropic nematode that requires the CNS of mammalian hosts for its growth; the third-stage larvae frequently invade skeletal muscles and the nervous system. Strongyloides, a gastrointestinal nematode, is known to cause CNS involvement in immunosuppressed patients. Recently, some nematodes heretofore unknown to cause human parasitism have been recognized as the causative agents of CNS infections.

Africa↗
PubMed1997

Molting hormonal and larvicidal activities of aliphatic acyl analogs of dibenzoylhydrazine insecticides.

Dibenzoylhydrazines are the nonsteroidal ecdysone agonists. Using comparative molecular field analysis, we previously found that the alkyl side chain of 20-hydroxyecdysone (20E) is three-dimensionally superposable with one of their two aryl moieties. To identify the aryl moiety that is better superposable on the alkyl chain, we synthesized compounds in which one of the two aryl groups of tebufenozide (N-t-butyl-N-3,5-dimethylbenzoyl-N'-4-ethylbenzoylhydrazine) is replaced by alkyl groups such as C4H9, C5H11, and C6H13. The molting hormonal activity of these compounds was measured using cultured integuments prepared from rice stem borers, Chilo suppressalis Walker, in terms of stimulation of incorporation of N-acetyl-[14C]glucosamine. N-t-Butyl-N-3,5-dimethylbenzoyl-N'-acylhydrazines with a hexanoyl or heptanoyl group were about 20-fold higher than that of 20E, whereas N-acyl-N-t-butyl-N'-4-ethylbenzoylhydrazines with a hexanoyl or heptanoyl group were much weaker than 20E. Their larvicidal activity was also measured against rice stem borers. The former series of compounds were much more active than the other series as well as 20E. Thus, the benzoyl moiety of dibenzoylhydrazines, which is bound to the secondary nitrogen atom (-NH-), is replaceable by aliphatic acyl groups without greatly affecting the biological activities.

Acylation↗
PubMed1997

Ultrastructure of cholesterol gallstones as observed by electron microscopy after freeze-fracturing.

The ultrastructure of cholesterol gallstones (mixed type) was studied in detail for the first time under the transmission electron microscope after freeze-fracturing. Gallstones consisted essentially of cholesterol crystals, some impurities, and fluid. In accord with the theoretical 3.4 nm bilayered structure of cholesterol crystals, 3-4 nm periodicity of crystal layering was observed. However, gallstone cholesterol crystals were not perfect and often showed structural defects. Between crystals, complete edge-to-surface, edge-to-edge and surface-to-surface adhesions, and overall block-like aggregations were found. These may represent the structural basis for the stability of cholesterol crystal aggregation. The easy breakdown of cholesterol gallstones by extracorporeal shock wave lithotripsy is discussed in relation to their ultrastructure.

Aged↗
PubMed1997

Antigenic similarities to Paracoccidioides brasiliensis in thermo-dependent dimorphic fungi isolated from soil in Botucatu, SP, Brazil.

We compared the antigenic characteristics of two thermo-dependent dimorphic fungi isolated from soil in Botucatu, an endemic area of paracoccidioidomycosis (PCM) and Paracoccidioides brasiliensis. The soil isolates grew as cerebriform colonies at 37 degrees C (yeast form) and as cottonous colonies at 25 degrees C (mycelial form). No pathogenicity for ddY mice or hamsters were observed. In immunodiffusion test, there were precipitation bands between the 2 soil isolates and pooled PCM patient sera. There were also common precipitation bands at 21, 50 and 58 kDa between the soil isolates antigens and PCM patient sera by Western-blotting, but no gp43 kDa band. No gene for gp 43 kDa protein was detected in the soil isolates by PCR. The fact that these isolates were obtained from an endemic area of PCM and there were some antigenic similarities between the soil isolates and P. brasiliensis in immunodiffusion test and Western-blotting may have some importance in epidemiological surveys done with paracoccidioidin as well interfering with the immune response of the exposed population.

Animals↗
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

Periodontal parameters of osseointegrated dental implants. A 4-year controlled follow-up study.

The aim of this study was to evaluate the periodontal parameters of osseointegrated dental implants. The condition of the peri-implant mucosa was assessed using periodontal parameters, i.e., of plaque index, bleeding on probing, probing pocket depth, probing attachment level and Periotest scores as well as a radiographic parameter, over a 4-year follow-up period. 32 non-submerged ITI dental implants, all placed in the mandible, were studied in 12 patients who had good oral hygiene. All patients were regularly recalled at 6-month intervals. The overall implant success rate was 100%. None of the implants showed any signs of inflammation, radiographic bone loss or any detectable mobility during the follow-up period. Methods similar to those used to evaluate the natural dentition were effectively employed to assess the clinical status of the dental implants. The diagnostic value of these parameters could not, however, be determined from this study due to the absence of any peri-implant tissue complications. The results indicated that some periodontal parameters of healthy peri-implant mucosa might be slightly different from healthy periodontal tissue.

Alveolar Process↗
PubMed1997

Role of Na(+)-K+ ATPase in cyclic GMP-mediated relaxation of canine pulmonary artery smooth muscle cells.

1. Sodium-potassium adenosine triphosphate (Na(+)-K+ ATPase) plays a role in the regulation of vascular tone, but contribution of this enzyme to intravasodilator-induced pulmonary vasodilation remains uncertain. We thus studied the interaction between guanosine 3':5'-cyclic monophosphate (cyclic GMP) and Na(+)-K+ ATPase in smooth muscle cells isolated from canine pulmonary artery. 2. To assess the contractile properties, changes in smooth muscle cell length were determined microscopically. Application of potassium chloride (KCl) shortened the cell length, an effect which was reduced by sodium nitroprusside and 8-bromo-cyclic GMP in a concentration-dependent manner. Pretreatment of cells with the cyclic GMP-dependent kinase inhibitor KT 5823 (2 microM) abolished the effects of sodium nitroprusside and 8-bromo-cyclic GMP. 3. Ouabain (0.3 microM) did not alter the KCl-induced muscle shortening, but inhibited the relevant responses to sodium nitroprusside and 8-bromo-cyclic GMP. 4. Incubation of smooth muscle cells with sodium nitroprusside concentration-dependently increased intracellular cyclic GMP levels and ouabain-sensitive 86Rb uptake, and these values were significantly correlated. In the presence of KT 5823, sodium nitroprusside increased cyclic GMP levels but did not alter ouabain-sensitive 86Rb uptake. 5. These results suggest that there is a link between accumulation of intracellular cyclic AMP and activation of sarcolemmal Na(+)-K+ ATPase in pulmonary artery smooth muscle cells and that this link may be involved in the sodium nitroprusside-induced pulmonary vasodilatation.

Animals↗
PubMed1997

Nucleotide sequence and transcriptional analysis of the flanking region of the gene (spb) for the trans-acting factor that controls light-mediated expression of the puf operon in Rhodobacter sphaeroides.

We recently reported the existence of a trans-acting factor (SPB) in Rhodobacter sphaeroides that repressed the expression of the puf operon during illumination. SPB was somewhat homologous to HvrA of Rhodobacter capsulatus, but these proteins appear to have functionally different properties. We now report an analysis of the flanking region of spb in the genome of R.sphaeroides, and we show that spb is a positional counterpart of hvrA of R. capsulatus. The region directly downstream of spb was found to contain three genes, two of which were highly homologous to orf5 and ahcY in R. capsulatus. However, a gene corresponding to hvrB, which controls the expression of orf5 and ahcY in R. capsulatus, was absent in R. sphaeroides. The level of the transcript of ahcY did not change in cells grown under photosynthetic and by respiratory conditions. By contrast, orf5 was transcribed at a higher rate in photosynthetically grown cells under high-intensity light than under low-intensity light, indicating features of transcription different from those in R. capsulatus. A third gene, orf318, which was absent in the corresponding region of R. capsulatus, encoded an amino acid sequence that was significantly homologous to the consensus sequence of RfaI and RfaJ of E.coli, which are glycosyl transferases involved in the synthesis of lipopolysaccharide. orf318 was transcribed in the opposite direction to ahcY, and at only a low level, under all conditions tested.

Amino Acid Sequence↗