Biomedical subjects

N Kasai

Publications and source records attributed to N Kasai.

At least 37 records · Page 2Linked to original sources

PubMed2001

Antibody levels in goats fed Toxoplasma gondii oocysts.

Outbred goats were fed 10(5) Toxoplasma gondii oocysts and were monitored twice weekly for 8 wk for rectal temperature, clinical signs, parasitemia, and antibody levels by indirect fluorescence antibody test (IFAT), latex agglutination test (LAT), and indirect enzyme-linked immunosorbent assay (ELISA). After 8 wk, all goats were killed, and samples of heart, skeletal muscle, brain, lymph nodes, kidneys, and liver were bioassayed in mice. Anorexia, fever, and lethargy were observed from day 3 to day 7 postinfection (PI). Parasitemia was detected by bioassay in 50% of infected goats from day 7 to day 14 PI. Viable T. gondii organisms were isolated from all infected goats. Antibodies to T. gondii were detected in some animals on day 10 PI by IFAT and LAT and on day 14 PI by ELISA. The infected goats were seropositive on day 17 PI.

Animals↗

PubMed2001

Isolates of Sarcocystis falcatula-like organisms from South American opossums Didelphis marsupialis and Didelphis albiventris from São Paulo, Brazil.

Isolates of Sarcocystis falcatula-like organisms from South American opossums were characterized based on biological and morphological criteria. Sporocysts from intestinal scrapings of 1 Didelphis marsupialis and 8 Didelphis albiventris from São Paulo, Brazil, were fed to captive budgerigars (Melopsittacus undulatus). Budgerigars fed sporocysts from all 9 isolates became ill and S. falcatula-like schizonts were identified in sections of their lungs by immunohistochemical staining. Sarcocystis falcatula-like organisms were cultured from lungs of budgerigars fed sporocysts from D. marsupialis and from lungs of budgerigars fed sporocysts from 3 of 8 D. albiventris. The 33/54 locus amplified by polymerase chain reaction from culture-derived merozoites contained both a HinfI endonuclease recognition site previously suggested to diagnose S. falcatula and a DraI site thought to diagnosed S. neurona. Development of the isolate from D. marsupialis was studied in cell culture; its schizonts divided by endopolygeny, leaving a residual body. Morphological and genetic variation differentiated this Sarcocystis isolate originating in D. marsupialis from the Cornell I isolate of S. falcatula. This is the first report of a S. falcatula infection in the South American opossum, D. marsupialis.

Animals↗

PubMed2001

Genetic alteration of penicillin non-susceptible Streptococcus pneumoniae observed throughout recurrence of acute otitis media detected by amplified fragment length polymorphism analysis.

The prevalence of penicillin non-susceptible Streptococcus pneumoniae (PNSSP) is increasing among isolates from acute otitis media (AOM). Repeated episodes of antibiotic exposure are a well-known risk factor for the isolation of PNSSP although otitis-prone or recurrent AOM cases frequently require repeated courses of antibiotic treatment. In order to evaluate the chronological alteration of S. pneumoniae during recurrences of AOM, strains of S. pneumoniae were isolated from 11 patients, each of whom had experienced 2-4 episodes of AOM, were examined. Every bacterial specimen obtained from a single episode of recurrent AOM was examined by PCR-based penicillin-binding protein (PBP) assay, serotyping, and amplified fragment length polymorphism (AFLP), then compared to other samples from the same case. Two cases (18.2%) showed strain diversity during repeated antibiotic treatments by serotyping or PBP-assay. By AFLP analysis, 6 cases (54.5%) demonstrated heterogeneous strains during recurrent AOM. Clonal survivors of previous episodes of AOM were not always the cause of subsequent episodes of AOM, even in otitis-prone cases.

Acute Disease↗

PubMed2001

[Peritoneal sclerosis in children under treatment with peritoneal dialysis].

Peritoneal dialysis(PD) is an established method of dialysis for children at the end stage of renal failure. Among several problems associated with PD, peritoneal sclerosis is one of the most serious complications. We examined four children on PD who were diagnosed as having peritoneal sclerosis in 1997 and 1998. Three of these cases were switched to hemodialysis(HD) and one is now undergoing a switch from PD to HD. Although all of the four patients had a history of bacterial peritonitis, they had been maintained in a fairly good condition on PD. The mean duration of PD was 9 years(4-14 years). All cases were anuric and had been maintained on PD without any problems of peritoneal function. From these observations, we should consider peritoneal sclerosis even in patients with a good clinical condition during the long-term period of PD. We recommend serial peritoneal biopsies, at least at the time of peritoneal catheter changes, to check for peritoneal sclerosis. The patients who are diagnosed as having sclerotic thickening of the peritoneal membrane should be switched from PD to HD to prevent the occurrence of life-threatening peritoneal sclerosis.

Adolescent↗

PubMed2000

The South American opossum, Didelphis marsupialis, from Brazil as another definitive host for Sarcocystis speeri Dubey and Lindsay, 1999.

The North American opossum, Didelphis virginiana, is a definitive host for at least 3 species of Sarcocvstis: S. falcatula Stiles 1983, S. neurona Dubey, Davis, Speer, Bowman, de Lahunta, Granstrom, Topper, Hamir, Cummings, Suter 1991, and S. speeri Dubey and Lindsay 1999. In order to identify species of Sarcocystis in the South American opossum, D. inarsupialis, Sarcocystis sporocysts from the intestines of a naturally infected opossum (D. marsupialis) from Brazil were fed to 4 gamma-interferon knockout (KO) mice, a nude mouse, and 2 budgerigars (Melopsittacus undulatus). All 4 KO mice became ill and 1 died 42 days post-feeding (p.f.) of sporocysts, 1 was killed 44 days p.f. because of neurological signs, and 2 were killed 52 and 53 days p.f. because of abnormal gaits. Numerous sarcocysts were seen in the skeletal muscles of all 4 KO mice and they were structurally identical to S. speeri seen in KO mice fed sporocysts from D. virginiana from the United States and D. albiventris from Argentina. The nude mouse was killed 41 days p.f. because it appeared weak; schizonts were seen in sections of its liver and sarcocysts were seen in sections of skeletal muscles. Sarcocystis speeri was cultured in bovine turbinate cells inoculated with liver homogenate from this mouse. Sarcocystis neurona was not demonstrable in tissues of mice. The two budgerigars remained asymptomatic and S. falcatula was not found in their tissues when they were killed 29 days p.i. This is the first report of S. speeri from D. marsupialis.

Animals↗

PubMed2000

Isolation and characterization of monoclonal antibodies that inhibit hepatitis C virus NS3 protease.

A series of mouse monoclonal antibodies (MAbs) to the nonstructural protein 3 (NS3) of hepatitis C virus was prepared. One of these MAbs, designated 8D4, was found to inhibit NS3 protease activity. This inhibition was competitive with respect to the substrate peptide (K(i) = 39 nM) but was significantly decreased by the addition of the NS4A peptide, a coactivator of the NS3 protease. 8D4 also showed marked inhibition of the NS3-dependent cis processing of the NS3/4A polyprotein but had virtually no effect on the succeeding NS3/4A-dependent trans processing of the NS5A/5B polyprotein in vitro. Epitope mapping of 8D4 with a random peptide library revealed a consensus sequence, DxDLV, that matched residues 79 to 83 (DQDLV) of NS3, a region containing the catalytic residue Asp-81. Furthermore, synthetic peptides including this sequence were shown to block the ability of 8D4 to bind to NS3, indicating that 8D4 interacts with the catalytic region of NS3. The data showing decreased inhibition potency of 8D4 against the NS3/4A complex suggest that 8D4 recognizes the conformational state of the protease active site caused by the association of NS4A with the protease.

Amino Acid Sequence↗

PubMed2000

[Henoch-Schönlein purpura nephritis (HSPN) in children: comparison of the incidence and severity between two 12-year groups].

From 1971 to 1982, we treated 286 patients of HSP in Kitasato University Hospital. In these 286 patients, 137 developed purpura nephritis (47.9%). During the second 12-year period (from 1985 to 1996), we treated 34 HSPN patients among 189 HSP patients (18.0%). The clinico-pathological evaluations and comparisons in 30 cases from 1971 to 1982 and in 11 cases from 1985 to 1996 were performed, using the ISKDC grading. The numbers of patients of HSP and the incidence of HSPN both decreased in the more recent 12-year group. Furthermore, the severity of the renal histopathological findings decreased in the more recent group as well.

Adolescent↗

PubMed1999

Resistance to pseudorabies virus infection in transgenic mice expressing the chimeric transgene that represses the immediate-early gene transcription.

A chimeric gene encoding a fusion protein consisting of the DNA-binding domain of the immediate-early (IE) protein of pseudorabies virus (PRV) and a tail-truncated VP16 of herpes simplex virus 1, lacking the transcription activation domain, has been shown to repress transcription of the PRV IE gene, resulting in the inhibition of PRV growth in vitro. To assess the antiviral potential of the fusion protein in vivo, transgenic mice containing the chimeric gene under the control of the virus- and interferon-inducible Mx 1 promoter were generated. A transgenic mouse line showed marked resistance to PRV infection when the mice were challenged intranasally with PRV. Inhibition of PRV replication was also observed in monolayers of embryonic cells prepared from the transgenic mice. In the cells infected with PRV, transcription of the PRV IE gene was repressed. The present results indicate that the chimeric gene is able to exert a significant antiviral effect against PRV infection in vivo.

Animals↗

PubMed1999

Odorant detection capability of QCR sensors coated with plasma deposited organic films.

Odorant-detection experiments were conducted on major single-odor substances in various types of botanical species. The sensing devices we used were quartz-crystal resonators (QCRs), radio-frequency (RF) sputtered with amino acids or polymers. The odorants were generated at very low concentrations (ppb level) by using the diffusion-tube method. The tested odorants were detected at concentrations between 0.3 and 940 ppb. These deposited films had high partition coefficients for the odorants, confirming their high sensitivity to organic vapors, especially to terpenoids. This indicates that the odorant solvation is due to odorant-film interaction related to Gibbs free energy.

Biosensing Techniques↗

PubMed1999

Ovine MHC class II DRB1 alleles associated with resistance or susceptibility to development of bovine leukemia virus-induced ovine lymphoma.

For the further characterization of bovine leukemia virus (BLV)-induced leukemogenesis, we investigated the association between polymorphism of ovine leukocyte antigen (OLA)-DRB1 gene and tumor development after infection of sheep with BLV. We infected 28 sheep with BLV and cloned exon 2 of the OLA-DRB1 gene from asymptomatic animals and from animals with lymphoma Sequence analysis revealed that, among 12 healthy sheep without any evidence of tumor, ten (83.3%) carried DRB1 alleles encoding Arg-Lys (RK) at positions beta70/71 as compared with only 6 (37.5%) of the 16 sheep with lymphoma, which suggested that alleles encoding the RK motif might protect against development of tumors after infection by BLV. By contrast, alleles encoding Ser-Arg (SR) at positions beta70/71 were present at a significantly elevated frequency in sheep with lymphoma as compared with the healthy carriers, which indicated that OLA-DRB1 alleles encoding the SR motif might be positively related to susceptibility to tumor development. The two amino acids in these motifs line a pocket that accommodates the side chain of a bound peptide according to a model of the crystal structure of human leukocyte antigen (HLA)-DR1. To analyze immunoreactions of sheep with alleles that encoded RK or SR at beta70/71, we selected sheep with either the RK/SR genotypes or the SR/SR genotypes and immunized them with a mixture of multiple synthetic antigenic peptides that corresponded to T-helper, T-cytotoxic, and B-cell epitopes of the BLV envelope glycoprotein gp51. Two weeks after the last immunization, all of the sheep were challenged with BLV. Sheep with the RK/SR genotype produced neutralizing antibodies against BLV; they eliminated BLV completely within 28 weeks of the BLV challenge, and they gave strong lymphocyte-proliferative responses to the peptides used for immunization. Moreover, such animals did not develop lymphoma. By contrast, sheep with the SR/SR genotype continued to produce BLV throughout the experimental period and developed terminal disease. Our results indicate that the differences in immunoresponse were due to differences in major histocompatibility complex class II alleles and reflected the risk of BLV-induced leukemogenesis. In addition, it appears that susceptibility to tumor development may be determined to some extent by polymorphic residues binding to antigenic peptides directly within the binding cleft of the OLA-DR molecule.

Alleles↗

PubMed1999

A gene for fluctuating, progressive autosomal dominant nonsyndromic hearing loss, DFNA16, maps to chromosome 2q23-24.3.

The sixteenth gene to cause autosomal dominant nonsyndromic hearing loss (ADNSHL), DFNA16, maps to chromosome 2q23-24.3 and is tightly linked to markers in the D2S2380-D2S335 interval. DFNA16 is unique in that it results in the only form of ADNSHL in which the phenotype includes rapidly progressing and fluctuating hearing loss that appears to respond to steroid therapy. This observation suggests that it may be possible to stabilize hearing through medical intervention, once the biophysiology of deafness due to DFNA16 is clarified. Especially intriguing is the localization of several voltage-gated sodium-channel genes to the DFNA16 interval. These cationic channels are excellent positional and functional DFNA16 candidate genes.

Adolescent↗

PubMed1999

[A case of carcinoma of lower lip showing excellent response to chemotherapy with UFT].

We report a case of squamous cell carcinoma of the lower lip showing an excellent response to chemotherapy with UFT. A 68-year-old woman with a painless swelling of her lower lip was refereed to our service. This tumor was 19 x 18 mm with cauliflower surface, and induration was noted around the mass. The pathological diagnosis was squamous cell carcinoma of well-differentiated type. After chemotherapy with UFT (400 mg/day), the tumor became flat. It was then removed with a 7 mm-safety margin and the lower lip was reconstructed with an Abbe-Estlandar flap from the upper lip. Post-operative histological findings indicated a complete response. Wound healing was uneventful, and there has been no evidence of recurrence for these 6 months after the operation. This case is still under observation.

Aged↗

PubMed1998

In vivo analysis of hydrogen peroxide and lipid radicals in the striatum of rats under long-term administration of a neuroleptic.

It has been hypothesized that free radicals play a causative role in tardive dyskinesia, which is an inveterate movement disorder caused by chronic administration of neuroleptics. To verify this hypothesis, rats were reared while being regularly treated with water containing a neuroleptic, haloperidol (HPD), for 1 year (HPD group). The changes in the striatal hydrogen peroxide content of the rats in the HPD and control groups were measured by using a Pt-disk microelectrode while the animals were in a freely moving state following intraperitoneal administration of HPD (HPD challenge). We also performed electron spin resonance (ESR) detection of lipid radicals in the striatum before the HPD challenge. HPD challenge led to significant elevation of the intrastriatal hydrogen peroxide in all animals, but the elevation in the HPD group was smaller than that in the control group. However, in the HPD group, marked ESR signals of intrastriatal lipid radicals were observed. We think that these results support the hypothesis on the role of free radicals in tardive dyskinesia.

Animals↗

PubMed1998

Identification of homozygous lipoprotein lipase gene mutation in a woman with recurrent aggravation of hypertriglyceridaemia induced by pregnancy.

We herein report a case of a 40-year-old Japanese woman (patient IT) with a history of recurrent aggravation of hypertriglyceridaemia, pancreatitis and miscarriages in three previous pregnancies. However, strict dietary intervention was applied during a fourth pregnancy. As a result, acute pancreatitis was avoided, and the patient gave birth to a healthy infant. In patient IT, the underlying etiology of the recurrent aggravation of hypertriglyceridaemia during pregnancy was a lipoprotein lipase (LPL) gene aberration. She was homozygous for LPL deficiency due to a nonsense mutation (TGG1401 --> TGA/Trp382 --> Stop) in exon 8 of the LPL gene, which resulted in the absence of LPL activity and immunoreactive LPL mass. Our findings indicate that, in LPL deficiency, pregnancy seriously exacerbates hypertriglyceridaemia and increases the risk of acute pancreatitis, which endangers both the mother and fetus. Early diagnosis of LPL deficiency and appropriate management thereof are essential for normal childbirth.

Abortion, Habitual↗

PubMed1998

[Clinical and bacteriological studies on panipenem/betamipron in pediatrics. Kanagawa Research Group for Infectious Diseases of Children].

Following its introduction into the market, PAPM/BP (panipenem/betamipron) was clinically studied in 188 evaluable cases out of 207 cases primarily of respiratory infectious diseases treated at the pediatric departments of 15 hospitals. In the clinical evaluation, the drug proved effective in three of three cases of sepsis; three of three cases of suppurative meningitis; nine of ten cases of laryngopharyngitis, six of seven cases of tonsillitis, 56 of 63 cases of acute bronchitis, 90 of 98 cases of pneumonia, and one of one case of phyothorax, all of which are respiratory infectious diseases; one of one case of secondary infection of a chronic respiratory disease; and two of two cases of lymphadenitis, which is a disease of the soft dermal structure. The overall efficacy rate was 91.0% (171/188 cases). In the bacteriological study, Gram-positive bacteria were eliminated in five of five strains of S. aureus, 30 of 31 strains of S. pneumoniae (96.8%), and three of three strains of S. pyogenes. Gramnegative bacteria were eliminated in 15 of 17 strains of H. influenzae (88.2%), three of four strains of M. catarrhalis, and two of two strains of K. pneumoniae. The overall elimination rate was 92.1% (70/76 strains). In the 23 strains of S. pneumoniae that were examined, penicillin-resistant strains accounted for 56.5%, showing an elimination rate of 100%. No serious adverse effects were observed, and the incidence of adverse effects was 1.45%. As for abnormalities in laboratory tests, levels of GOT and GPT increased in eight cases (3.88%), LDH increased in one case (0.48%), and neutropenia occurred in one case (0.51%). These results suggest that PAMP/BP could be considered the first choice in the treatment of infectious diseases in pediatrics, due to its effectiveness and high level of safety.

Adolescent↗

PubMed1997

Cryptosporidium muris in dairy cattle in Brazil.

A total of 580 fecal samples from 30 cows and their calves from three dairy farms in São Paulo State, Brazil, was collected monthly over a period of 1 year (April 1994 to March 1995). A combination of water-ether centrifugal sedimentation technique followed by sucrose centrifugal flotation was used for neonatal samples and sucrose centrifugal flotation for the remainder of the samples. Cryptosporidium muris was found in calves from all farms, although the parasite was not detected in the dams. C. muris oocysts were excreted by 14 of the 30 calves, on at least one occasion during the year. Of the 307 calf fecal samples examined, 53 (17.3%) were positive for C. muris. The mean persistency of oocyst shedding in feces was 4 +/- 3 months. Sixty-four per cent of the positive calves excreted few oocysts, while 36% discharged many oocysts for a longer period (P < 0.05). Oocysts were first detected at the mean age of 3 +/- 1 months. The age of the positive calves ranged from 6 weeks to 14 months.

Animals↗

PubMed1997

Progressive effect of alpha-phenyl-N-tert-butyl nitrone (PBN) on rat embryo development in vitro.

In the present study we demonstrated the effects of the spin-trapping agent alpha-phenyl-N-tert-butylnitrone (PBN) on the in vitro development of rat embryos at the early stage. In rat embryos, PBN increased the speed of the first cleavage and had no toxicity during pregnancy after embryo culture. These results showed that reactive oxygen species (ROIs) that were formed by activating molecular oxygens through redox reactions regulated the speed of development for early-stage embryos. Thus, PBN caused a decrease in the level of ROIs and toxicity and an in increase in the level of the development of rat embryos. On the other hand, PBN could not decrease the 2-cell block in vitro nor increase the blastulation rate, in contrast to the fact that a scavenger of superoxide anions, SOD, is effective in doing so for mouse embryos. From these results it was concluded that free radicals play an important role in the in vitro development of rat embryos at the early stage, but play no role in the decrease of the 2-cell block or their blastulation rate. It should be noted that PBN had no toxicity for embryonic development at the 2-cell stage.

Animals↗

PubMed1997

Hydrogen peroxide augmentation in a rat striatum after methamphetamine injection as monitored in vivo by a Pt-disk microelectrode.

We fabricated a Pt-disk microelectrode (diameter 30 microns) to conduct differential double-pulse amperometry (first step: 750 mV, 1 s; second step: 1,100 mV, 1 s) to detect hydrogen peroxide in the brain of a freely moving animal. This measurement determined hydrogen peroxide (detection limit, 0.03 microM) without any observable influence from other oxidizable species, such as dopamine (DA), ascorbic acid, or uric acid. The electrode was implanted into the right striatum of a rat. After intraperitoneal injection of methamphetamine (MAP), hydrogen peroxide concentrations were directly detected while the behavioral changes were monitored. MAP injection led to significant augmentation of hydrogen peroxide, the elevation of which depended on the dose of MAP. This is consistent with a previous report on the increase of DA-release caused by amphetamines and indirect evidence of the production of hydrogen peroxide via DA-metabolism.

Animals↗