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Biomedical subjects

M Nakazawa

Publications and source records attributed to M Nakazawa.

At least 199 records · Page 11Linked to original sources

An enzyme-linked immunosorbent assay (ELISA) for the detection of antibody against Streptococcus suis type 2 in infected pigs.

An ELISA test for the detection of antibody against S. suis type 2 in pigs was developed and applied to field sera. The best sensitivity and specificity of ELISA were obtained when a purified polysaccharide antigen was used. It showed no cross reaction with sera against other serotypes of S. suis and other pathogenic bacteria. A total of 264 sera were collected from 20 pig farms and examined with the antibody against S. suis type 2. In the affected farms, 17.0% of pigs tested were positive, 9.8% in the adjacent farms, but only 3.4% in the free farms. The difference of the positive percentages between the affected and the free farms was statistically significant (P < 0.05).

Animals↗

[A 13-week oral toxicity study of prulifloxacin (NM441) in rats followed by a 5-week recovery test].

A repeated dose toxicity study of prulifloxacin, a new antibacterial agent, was conducted in Sprague-Dawley rats. Male and female rats were given the test material orally for 13 weeks at doses of 0 (control), 30, 170 and 1000 mg/kg. After discontinuation of the treatment, a 5-week recovery test was also conducted. Salivation, soft feces, reduced body weight gain and increased water consumption were seen in the 1000 mg/kg group. There were no treatment-related effects on survival and food consumption. Ophthalmoscopic and hematologic examinations failed to show any abnormalities attributable to the treatment. Urinalysis revealed increased urine volume and decreased K+ excretion in the 1000 mg/kg group. Blood chemical examination showed increased BUN, decreased triglyceride, K+, Cl- and total protein in the 1000 mg/kg group. Pathological changes caused by the treatment were as follows. Renal tubular nephrosis with crystalline substance was observed in the 170 and 1000 mg/kg groups. Renal weight was increased and crystalline substance was noted in the lumen of the urinary bladder in the 1000 mg/kg group. Cecal distention with increased its organ weight was observed in all dose groups and swelling of its absorptive cells was seen in the 170 and 1000 mg/kg groups. Swelling of jejunal goblet cells was observed in the 1000 mg/kg group. In femoral articular cartilage, focal accumulation of chondrocytes, small cavities and proliferation of fibrous tissue were seen in the 170 and 1000 mg/kg groups. The above-mentioned changes were reversible except for renal tubular nephrosis and cecal distention with its increased organ weight, of which the degree and frequency, however, were lowered. The cecal distention in the 30 mg/kg group was considered to be attributable to the pharmacological effect of the test material. The results show that the NOAEL of prulifloxacin is 30 mg/kg for 13-week repeated dose toxicity in rats.

Administration, Oral↗

Inhibition of outflow cushion mesenchyme formation in retinoic acid-induced complete transposition of the great arteries.

OBJECTIVE: Endocardial cushion tissue formation, the primordia of valves and septa, is a critical event in cardiac morphogenesis. Maternally administrated all-trans retinoic acid is known to induce complete transposition of the great arteries (TGA) in the mouse embryo. To address the mechanisms of TGA, the effect of retinoic acid on cushion tissue formation was examined. METHODS: Using a three-dimensional collagen gel culture model, we performed various types of endothelial-mesenchymal transformation assays of co-cultured endocardium with myocardium obtained from 9.5-day mouse embryonic hearts. In vivo immunohistochemical detections of extracellular matrices, fibronectin and type I collagen, were also performed. RESULTS: Endothelial-to-mesenchymal transformation at the onset of cushion tissue formation was suppressed in the outflow tract of embryos exposed to retinoic acid in culture. This inhibitory effect of retinoic acid was spatially restricted to the outflow tract and reversed by treatment with embryonic myocardial conditioned medium enriched in extracellular inductive molecules. Mesenchyme formation in the outflow tract was inhibited at a lower concentration of retinoic acid (10(-10) mol/l) than that which inhibited the atrio-ventricular canal (10(-7) mol/l) in culture. The fibronectin and type I collagen depositions in pre-migratory outflow tract cardiac jelly in retinoic acid-treated embryonic heart were reduced compared to those in the control. CONCLUSIONS: Exogenously applied retinoic acid inhibits outflow tract cushion mesenchyme formation in the embryonic heart with TGA. It is suggested that retinoic acid inhibits the expression of extracellular matrices and inductive molecules synthesized by myocardium in the outflow tract.

Animals↗

[Usefulness of endoscopic ultrasonography in deciding indication for high dose rate intracavitary brachytherapy for esophageal carcinoma].

We retrospectively analyzed 20 patients with stage I-IV esophageal carcinoma treated by limited external radiotherapy (EXR) combined with high dose rate intracavitary brachytherapy (ICBT) using 60Co as boost therapy. In 10 of 20 patients treated by combined therapy, we used endoscopic ultrasonography (EUS) before ICBT and measured the thickness of the residual tumor following external beam therapy. Of the patients treated by combined therapy, the local control rate of esophageal carcinoma with a thickness under 10 mm before ICBT was significantly better than that with a thickness over 10 mm (confidence limit 95%). Therefore, when administering high dose rate intracavitary brachytherapy after EXR, we should measure the thickness of esophageal carcinoma with millimeter unit precision. One of the most precise methods currently available for measuring thickness is EUS. Our results indicate that esophageal carcinoma under 10 mm in thickness after EXR is the most favorable indication for ICBT.

Aged↗

[CT findings of the irradiated intestinal wall: comparison of early vascular phase and delayed equilibrium phase].

The intestinal walls of the irradiated pelvic tumor cases of 20 patients were studied. CT manifestations of the irradiated intestinal wall were examined at the early vascular phase (examined 40 seconds after the injection of contrast medium by helical scan) and at the delayed equilibrium phase (examined 4 to 5 minutes after the injection of contrast medium by rapid sequence scan). Two characteristics were identified: intestinal wall thickening and a three-layered pattern. The former was better depicted on equilibrium phase, whereas the latter was clearer on early vascular phase. Differences in visualization of the wall thickening on vascular phase and delayed phase were statistically significant. The three-layered pattern was considered to suggest severe inflammatory edematous change of the intestinal wall. Early enhancement of the mucosal and muscular-serosal layers with less enhancement of the submucosal layer, and homogeneous distribution of the contrast medium to the interstitium on delayed phase were considered to be the reason.

Adult↗

[A quantitative study of regional cerebral blood flow in patients with dementia of Alzheimer type using single photon emission computed tomography--clinical application of the IMP autoradiographic method (IMP ARG method)].

We quantitatively measured regional cerebral blood flow (rCBF) in 37 patients with dementia of Alzheimer type (DAT) to investigate the clinical utilities of the N-isopropyl-p-[123I]iodoamphetamine autoradiographic method (IMP ARG method) that is a quantitative method more simplified and less invasive for IMP-SPECT developed by Iida et al. A given standard input function and a given value of distribution volume (Vd) used for the rCBF measurement of this method were calculated from the dynamic study by six normal volunteers. Mean values [SD] of rCBF (ml/ 100 g/min) in the Cerebral Cortex were 49.0 [6.0] in the controls (n = 20), 42.6 [5.9] in mild DAT group (n = 14), 36.7 [5.5] in moderate DAT group (n = 12), and 26.4 [7.5] in severe DAT group (n = 11), respectively. These values were significantly different between each neighboring group. Moreover, the correlations between the score by the Hasegawa dementia scale (HDS-R) and each rCBF were significant in the temporal, parietal, and frontal cortex. These findings suggest that the rCBF measurement in IMP-SPECT using this method is useful for the diagnosis of the clinical severity in patients with DAT.

Aged↗

Neuronal apoptosis by glial NO: involvement of inhibition of glyceraldehyde-3-phosphate dehydrogenase.

In primary cocultures of neurons and glial cells prepared from the neonatal rat brain, lipopolysaccharide (LPS) reduced the numbers of neuronal cells but the effects were markedly inhibited by NG-monomethyl-L-arginine, indicating the involvement of NO and LPS-induced NO synthase in neuronal death. LPS stimulated the expression of inducible NOS (iNOS) in preparations of primary cultured microglias/astrocytes, but not in primary cultured neurons. In addition, LPS caused DNA fragmentation only in NG108-15 cells but not in primary cultured astrocytes as well as astrocytes in cocultures of the two cell types, suggesting that NOS induces the apoptosis of neurons but not glial cells. We then examined the NO-induced neuronal death in NG108-15 cells using NO donors. SNP, and NO donor, caused NO-2 accumulation in the reaction medium and lactate dehydrogenase (LDH) leakage from NG108-15 cells. Although SNP stimulated guanylyl cyclase and accumulated cGMP, cGMP analogs did not affect LDH leakage. In addition, SNP induced chromosomal condensation and fragmentation of nuclei in NG108-15 cells. Gel electrophoretic analysis of cellular DNA extracted from SNP-treated cells, confirmed the internucleosomal DNA fragmentation typical of apoptosis in this culture. SNP increased the amount of radioisotopic labeled glyceraldehyde-3 phosphate dehydrogenase (GAPDH) in the presence of [32P]NAD and inhibited the enzyme activity. The results suggested that SNP-induced cell death is partly due to the NO-induced inhibition of GAPDH, perhaps by stimulating the binding of NAD to GAPDH.

Animals↗

Left ventricular dysfunction on exercise long-term after total repair of tetralogy of Fallot.

BACKGROUND: Excellent results regarding mortality are well recognized in the long-term period after intracardiac repair of tetralogy of Fallot. However, it is still unclear how postoperative sequelae affect cardiac performance during exercise. METHODS AND RESULTS: Twenty-nine patients with tetralogy of Fallot were studied 16 +/- 2 years after intracardiac repair by use of radionuclide first-pass ventriculography with an ultra-high-sensitive gamma camera at rest and at peak exercise on a semi-upright bicycle ergometer. The results were compared with those from 10 age- and sex-matched control subjects. Left and right ventricular ejection fraction and absolute ventricular volume were measured at rest and peak exercise. Regional right ventricular wall motion and diastolic function of the left ventricle were also assessed. Cardiac output of tetralogy was normally preserved both at rest and during exercise. Nevertheless, the incremental response of left ventricular ejection fraction during exercise was depressed in the patients. Left ventricular ejection fraction during exercise was inversely correlated with the right ventricular end-diastolic volume and the severity of pulmonary regurgitation. Regional wall motion at the right ventricular outflow tract was not decreased in the patients. Left ventricular diastolic function was not impaired in the patients compared with control subjects. CONCLUSIONS: Latent left ventricular dysfunction during exercise is related to an enlarged right ventricle due to pulmonary regurgitation after intracardiac repair of tetralogy. Careful follow-up is required in patients having significant pulmonary regurgitation.

Adult↗

Morphological observations on the pathogenetic process of transposition of the great arteries induced by retinoic acid in mice.

BACKGROUND: The pathogenesis of complete transposition of the great arteries (TGA) is still controversial because useful animal models have not been established. We previously reported that all-trans retinoic acid induced complete TGA at a high proportion in mice. The aim of the present study was to clarify the morphogenesis of the cardiac outflow tract in the retinoic acid-treated embryos destined to develop TGA. METHODS AND RESULTS: We first examined the morphology of TGA in mouse fetuses treated with retinoic acid to establish an animal model of TGA (experiment 1) and then examined the retinoic acid-treated embryonic hearts by means of ink injection and histology (experiment 2). All mouse fetuses and embryos showed visceroatrial situs solitus and d-ventricular loop. In experiment 1, among 45 embryos treated with retinoic acid 70 mg/kg at day 8.5 of gestation, 35 (78%) had TGA and 3 (6.7%) had a double-outlet right ventricle with a subpulmonary ventricular septal defect. In experiment 2, all hearts already exhibited d-loop at gestation day 8.5. At gestation day 9.5, conus swellings, composed of acellular cardiac jelly, where hypoplastic, and the conotruncal cavity was nonspiral or tubular. At gestation day 11.0, aberrant conus swellings located anteroposteriorly to give a straight orientation to the conotruncal cavity. At gestation day 12.0, side-by-side great arteries were transposed in that the aorta arose from the right ventricle and the pulmonary artery arose above the interventricular foramen. CONCLUSIONS: These results suggest that a reproducible animal model of TGA can be produced in mice by treatment with retinoic acid; that there was no loop anomaly, such as an A-loop or L-loop, in our model; and that hypoplasia of the conus swellings appears to be the primary event leading to TGA.

Animals↗

HLA-DRB1 frequencies of non-Austronesian-speaking Gidra in south New Guinea and their genetic affinities with Oceanian populations.

DNA typing of HLA-DRB1 genes was conducted for 192 samples from the Gidra who speak one of the non-Austronesian languages and inhabit the southern lowlands of New Guinea. Comparison of the allele frequencies with those of eight other Oceanian populations reveals that the Gidra are genetically closest to the non-Austronesian-speaking Goroka and, next, to the Aboriginal Australian groups, but are remote from the Austronesian-speaking groups in mainland New Guinea and the rest of Melanesia. This finding clearly supports the hypothesis that non-Austronesians and Aboriginal Australians are descendants of the first-stage migrants to Oceania.

Adolescent↗

Immunocytochemical localization of secretory acetylcholinesterase of the parasitic nematode Nippostrongylus brasiliensis.

Various parasitic nematodes secrete acetylcholinesterase (AChE). In this study, the localization of AChE in the nematode Nippostrongylus brasiliensis and the secretory forms of AChE in culture fluid were examined. A thiocholine method revealed that AChE activity was localized in the subventral glands, which have a secretory and excretory function via a duct connected to the excretory pore. By electron microscopy, AChE activity was found mainly in the matrix of secretory granules, and sometimes in the Golgi apparatus in the subventral gland cells. These results show that nematode AChE is produced and stored in the subventral glands. Monoclonal antibodies against AChE of human erythrocytes or electric rays also bound to the nematode subventral gland, suggesting immuno-cross-reactivity of AChE among these species. When AChE activity in the nematode excretory-secretory product was examined by SDS polyacrylamide gel electrophoresis combined with the thiocholine method, intense activity was demonstrated as a single band at 74 kDa. Immunoblot analysis showed specific recognition of this molecule by IgE and IgG1 antibodies, but not by IgG2a antibody, in nematode-infected rat sera. These results indicate that the nematode AChE molecule produced in and secreted from the subventral glands is antigenic for the production of IgE/IgG1 in host animals.

Acetylcholinesterase↗

Contribution of cyclic GMP generation to the relaxation by nipradilol in the rabbit aorta.

1. Contribution of cyclic GMP generation to the relaxation by nipradilol of vascular smooth muscle was studied in the isolated rabbit aorta contracted by phenylephrine (10(-7) M) or prostaglandin F2 alpha (PGF2 alpha, 3 x 10(-6) M). 2. Nipradilol-induced relaxation in both contractions and increase in cyclic GMP content were inhibited by methylene blue (10(-5) M). 3. The relations between the increase in cyclic GMP and the relaxation produced by nipradilol and nitroglycerin were fitted to sigmoid curves. The increase in cyclic GMP at 50% relaxation by nipradilol was smaller than that by nitroglycerin (1.2-fold increase as against 3-fold increase). 4. These results suggest a smaller contribution of cyclic GMP generation through activation of soluble guanylate cyclase to nipradilol-induced relaxation in the rabbit aorta.

Adrenergic beta-Antagonists↗

An immunohistochemical investigation of porcine epidemic diarrhoea.

A sudden outbreak of epidemic diarrhoea of piglets occurred in Japan, the principal features being watery diarrhoea, dehydration and high mortality in newborn animals. The microscopical lesions were villous atrophy in the small intestine, the villous enterocytes being vacuolated and cuboidal in shape. The villus-crypt ratio was severely reduced, varying from 1:1 to 3:1. Transmission electron microscopy showed numerous coronaviruses within the cytoplasm of enterocytes and among microvilli. Specific antigens of porcine epidemic diarrhoea (PED) virus were detected in the cytoplasm of enterocytes by the streptavidin-biotin (SAB) technique. Infected cells, which were most abundant in the villous epithelia of the jejunum and ileum, were present in small numbers in the large intestine, the crypt epithelia, the lamina propria and Peyer's patches. The study suggests that the SAB technique is useful for the diagnosis of PED.

Animals↗

A homozygous 1-base pair deletion in the arrestin gene is a frequent cause of Oguchi disease in Japanese.

Oguchi disease is a rare autosomal recessive form of congenital stationary night blindness with all other visual functions, including visual acuity, visual field, and colour vision being usually normal. A typical clinical feature of the disorder is a golden or gray-white discolouration of the fundus which disappears in the dark-adapted state and reappears shortly after the onset of light ('Mizuo phenomenon'; Fig. 1). The course of dark adaptation of rod photoreceptors is extremely retarded in Oguchi disease while that of cones appears to proceed normally. The locus for Oguchi disease was recently mapped between D2S172 and D2S345 on distal chromosome 2q by linkage analysis. Interestingly, the gene for arrestin, an intrinsic rod photoreceptor protein implicated in the recovery phase of light transduction, also maps to this region of chromosome 2q (refs 6, 7). Here we report that in five out of six unrelated Japanese patients with Oguchi disease, we have identified a homozygous deletion of nucleotide 1147 (1147delA) in codon 309 of the arrestin gene, predicting a shift in the reading frame and a premature termination of translation which may result in 'functional null alleles.'

Adolescent↗

Macular dystrophy associated with monogenic Arg172Trp mutation of the peripherin/RDS gene in a Japanese family.

OBJECTIVE: Mutations of the peripherin/RDS gene have been reported in several kinds of retinal dystrophy, and they show variation of manifestation. In some pedigrees, the same mutation can produce different phenotypic features, a factor that makes it difficult to deduce certain rules for genotype-phenotype correlations in the peripherin/RDS gene. The authors report the phenotypic features of a Japanese family with a mutation in codon 172 of the peripherin/RDS gene and compare them to previously reported ocular findings in British pedigrees with the same mutation. PATIENTS AND METHODS: A 45-year-old man and his 15-year-old son were screened for mutations in the peripherin/RDS gene and the ROM1 gene. Clinical features were characterized by visual acuity and visual field testing, fundus examination, fluorescein angiography, and electroretinography. RESULTS: Both patients had the same mutation in codon 172 of the peripherin/RDS gene designated as Arg172Trp. No mutation was found in the ROM1 gene in either patient. Clinical features were summarized as autosomal dominant macular dystrophy. The father had sharply demarcated chorioretinal atrophy in the macula. The son showed mild granularity in the macular area in ophthalmoscopic appearances. CONCLUSIONS: The Arg172Trp mutation was confirmed to produce autosomal dominant macular dystrophy. This particular phenotype was caused by the monogenic mutation in the peripherin/RDS gene.

Adolescent↗

Early detection of cutaneous microcirculatory change during hemorrhage using a laser Doppler flowmetry.

The purpose of the present study was to evaluate the usefulness of cutaneous microcirculatory monitoring during hemorrhage. We observed changes in cutaneous blood volume, velocity and flow of five adult rabbits during hemorrhage by using a laser Doppler flowmetry. Mean arterial blood pressure, heart rate and blood gas values were measured. Cutaneous blood volume, velocity and flow decreased significantly after drawing 10 mL/kg of blood, while heart rate, mean arterial blood pressure and blood gas did not change. The decrease of cutaneous blood velocity preceded that of blood volume and was associated more deeply with the reduction of blood flow. In conclusion, cutaneous microcirculatory monitoring using laser Doppler flowmetry is a sensitive technique for detecting early changes of circulatory failure caused by hemorrhage.

Animals↗

[Experimental infection of infant rabbits with verocytotoxin-producing Escherichia coli of bovine origin].

Infant rabbits were used as a model to study the diarrhogenicity of verocytotoxin-producing Escherichia coli (VTEC) isolated from bovine. Infant rabbits aged 6 days were inoculated intragastrically with 10(9) viable bacteria of four VTEC or three non-VTEC strains. Of these strains, three strains (VT+, eaeA+), one strain (VT+, eaeA-) and one strain (VT-, eaeA+) caused diarrhea in rabbits 48 to 60 hr after inoculation. None of the two strains (VT-, eaeA-) caused symptoms. Based on these results, it is suggested that the 6-day-old infant rabbit is a suitable animal for studying diarrhea caused by VTEC or eaeA-positive E. coli strains of bovine origin.

Animals↗

Autosomal dominant cone-rod dystrophy with negative electroretinogram.

AIMS: The negative electroretinogram (ERG) is observed in many hereditary retinal disorders. However, no reports have described a negative ERG in a family with autosomal dominant cone-rod dystrophy. A Japanese family with autosomal dominant cone-rod dystrophy with negative ERG is described. METHOD: Members of a Japanese family with autosomal dominant cone-rod dystrophy were examined and evaluated with Goldmann and Humphrey perimetry, bright flash ERG with an intense white stimulus, rod, cone, and flicker ERGs, and fluorescein angiography. Molecular analysis of the rhodopsin and peripherin/RDS genes in the patients was also performed. RESULTS: A 45-year-old Japanese man (proband) presented with decreased visual acuity. His fundi revealed bull's eye maculopathy and his single flash bright ERG showed a negative configuration. Negative ERG responses also were found in his father, who had macular degeneration, and one of the proband's three children who showed no fundus changes. No irregularities were found in their rhodopsin or peripherin/RDS genes. CONCLUSION: The condition of this family is believed to represent a previously undescribed autosomal dominant cone-rod dystrophy.

Adolescent↗