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Biomedical subjects

S Yamazaki

Publications and source records attributed to S Yamazaki.

At least 163 records · Page 9Linked to original sources
PubMed1998

Mechanistic study on the roles of a bifidogenetic growth stimulator based on physicochemical characterization.

2-Amino-3-carboxy-1,4-naphthoquinone, discovered as a novel bifidogenetic growth stimulator (BGS), has been characterized by determination of redox and acid-base equilibria, partition properties, and UV-vis and electron spin resonance spectral properties. BGS is proposed to function as an electron transfer mediator from NADH to O2. BGS is reduced by NADH-reduced diaphorase (or related enzymes) and the reduced BGS is reoxidized by autoxidation and a peroxidase-catalyzed reaction. The proposed reaction would spare pyruvate as an important metabolic intermediate, and minimize the cytotoxic effects of H2O2 generated by the autoxidation. Kinetic studies were performed in model enzymatic systems using 2-methyl-1,4-naphthoquinone (VK3) as a reference compound with a very weak growth-stimulating effect. The results support our proposal and reveal the superiority of BGS to VK3 as an electron transfer mediator in the proposed reactions.

Bifidobacterium↗
PubMed1998

Genetic and serologic characterization of HIV type 1 prevailing in Myanmar (Burma).

To study the molecular epidemiology of HIV-1 spread in Myanmar and the interplay with the epidemic in surrounding Southeast Asian countries, we determined the HIV-1 subtypes prevailing in Myanmar. Thirty HIV-positive blood specimens were sampled in the capital city, Yangon, and an additional 459 sera were collected nationwide in 1995. Genetic subtyping based on the env C2/V3 sequence and serologic data, using a V3 peptide enzyme immunoassay (PEIA), revealed three patterns of HIV spread in different geographic regions in Myanmar: (1) in the capital city, Yangon, HIV-1 subtype B' ("Thai-B" cluster within subtype B) predominated both in IDUs and heterosexuals; (2) in the cities near the border with Thailand, including Tachelaik and Kawthaung, where heterosexual transmission is a major pathway of HIV-1 spread, HIV-1 subtype E was predominantly distributed among the commercial sex workers and heterosexuals; (3) in central and northeast Myanmar, both HIV-1 subtypes B' and E occurred in a mixed distribution, without showing any significant segregation by risk group. In addition, the PEIA data implied the occurrence of other subtype(s) in these areas. The interperson nucleotide sequence variations in env C2/V3 regions of B' and E, prevailing in Yangon, were 6.7 +/- 2.1 and 7.1 +/- 0.7%, respectively. They were similar to those levels observed in Thailand. These findings are consistent with the view that HIV spread in Myanmar might have taken place at about the same time as that in Thailand, and that multiple entries and exchanges of HIV-1 with neighboring countries are important factors contributing to the current distribution of subtypes in Myanmar.

Amino Acid Sequence↗
PubMed1998

Regulation by an extract of embryonic chick brain of the densities of voltage-dependent Na+ and Ca2+ channels in embryonic chick skeletal muscle cells during their development in culture.

We studied the chronic effects of a brain extract (BE) prepared from chick embryonic brains on voltage-dependent Na+ channels (VDNCs) and Ca2+ channels (VDCCs) during the development of chick skeletal muscle cells in culture. The maximum rates of rise of Na+ and Ca2+ action potentials were measured electrophysiologically in an attempt to determine the effects of BE on the densities of these channels. The basic culture medium was supplemented with chick transferrin instead of whole-embryo extract and skeletal muscle cells were grown in the absence or in the presence of crude BE or fractionated BE. Long-term inclusion of BE to the culture medium increased the densities of both VDNCs and L-type VDCCs. By contrast, BE apparently decreased the density of T-type VDCCs. Our results indicate that BE contains some protein(s) that has a negative effect on the density of T-type VDCCs of skeletal muscle cells at a less differentiated stage and that this effect of BE is closely associated with subsequent regulation of the densities of VDNCs and L-type VDCCs. Possible roles of the influx of Ca2+ ions through T-type and L-type VDCCs in the control of the densities of VDNCs and L-type VDCCs are discussed.

Animals↗
PubMed1998

Identification and molecular characterization of human T lymphotropic virus type II infections in intravenous drug abusers in the former South Vietnam.

Previous serological studies have demonstrated that some 60% of intravenous drug abusers (IVDAs) in urban areas of the former South Vietnam are infected with HTLV-II. In the present report we have attempted to characterize the viruses using restriction fragment length polymorphism (RFLP) and nucleotide sequence analysis of the provirus long terminal repeat (LTR) region. RFLP analysis of nine samples demonstrated that all were infected with the HTLV-IIb subtype. The HTLV-IIa subtype was not detected. Phylogenetic analysis of the nucleotide sequences demonstrated that the viruses clustered closely with HTLV-IIb isolates present in IVDAs from the New York City area. The present molecular analysis together with the previously reported absence of HTLV-II infection in North Vietnam supports the view that HTLV-II may have been introduced from the United States to this part of Asia by military personnel during the Vietnam conflict.

HTLV-II Infections↗
PubMed1998

[A successful valve repair case of isolated tricuspid regurgitation due to traumatic lacerated papillary muscle of the tricuspid valve].

A case of tricuspid valve regurgitation due to a non-penetrating chest trauma was presented. This case involves a 20-year-old man, who was admitted to a nearby hospital because of rib fracture, mandibular fracture, and hemorrhage of the left hemopneumothorax, caused by a traffic accident. Palpitation and chest discomfort were observed at admission time, but there was no follow-up. Tricuspid regurgitation was pointed out during surgery for the mandibular fracture, and he continued follow up treatment at an outpatient clinic. However his palpitation and chest discomfort worsened, and he was admitted to our department 8 month after injury. During surgery to repair the tricuspid valve, a papillary muscle rupture, valve cusp laceration, and anulus dilatation were found. We performed a papillary muscle repair (chorda tendineae reconstruction), valve cusp suture, and annuloplasty. Absence of the left pericardium was observed during the operation. We reported valve repair of traumatic tricuspid regurgitation which with papillary muscle rupture. Due to its rarity and the fact that there has been no reported cases of papillary muscle repair for traumatic tricuspid regurgitation in Japan, we used researched information on the subject.

Adult↗
PubMed1998

[Resection and reconstruction of sternum].

In case of sternal resection, it is necessary to preserve bone material indispensable for the stability of the anterior chest wall and air tightness of the thoracic cavity, and the support of the chest wall integrity must be restored by some means. Various techniques have been applied to the reconstruction of the chest wall following resection. During the last 10 years, we have performed reconstructive operation for 6 cases of the chest wall following resection of the sternum in recurrent cases of breast cancer or invaded case of primary breast cancer. In these patients, the chest wall was reconstructed using a rib-latissimus dorsi osteomyocutaneolus flap or a latissimus dorsi myocutaneous flap. The sternum was totally resected in 3 cases, and in all 3 cases, reconstructed using a rib-latissimus dorsi osteomyocutaneous flap. Although postoperative pulmonary function decreased, all cases could be relieved from endotracheal intubation within 17 hours after operation, and had no problems in activities of daily living or occurrence of chest flailing or paradoxical movement of the chest. An artificial material (expanded polytetrafluoroethlene patch) was used in only one patient for the reconstruction of the osseous thorax, but this case developed infection during postoperative chemotherapy. After this experience, we used only biological materials for the reconstruction of the chest wall and postoperatively performed radiotherapy and/or chemotherapy on all cases. We have observed no flap infection or detachment since then. One characteristic of using the latissimus dorsi myocutaneous flap is that it is easily elevated and rarely causes serious postoperative esthetic or functional problems. The flap is also easily utilized to reinforce the osseous thorax because ribs immediately below the latissimus dorsi muscle are readily mobilized as a pedicle graft. Reconstruction of the chest wall following resection of the sternum, described in this report, allowed us to perform radiotherapy and/or chemotherapy without serious postoperative complications on the cases relapsing after treatment of breast cancer. The 2-year survival rate is 50% and one of these cases survived up to 10 years after resection of the sternum. Thus we prefer to perform resection of the sternum for sternal recurrence of breast cancer if there are no metastatic lesions in other organs.

Adult↗
PubMed1998

[A successful case report of one and one half ventricle repair for pure pulmonary stenosis in a 4-year-old girl].

A 4-year-old girl with pure pulmonary stenosis, hypoplastic right ventricle and atrial septal defect, underwent left modified Blalock-Taussig shunt at the age of 2 year. Her RVEDV was 62.7% of normal and TVD was 64.2% of normal at the age of 3 year. We observed development of right ventricle and performed simultaneously Glenn shunt and right ventricular outflow reconstruction (one and one half ventricle repair). Her general condition after operation became better. The size of tricuspid valve and right ventricle grew on Cardiac ultrasonography and catheterization examined after one year operation. In future, If the size of RV and TV might grow further, we should recommend her biventricular repair.

Child, Preschool↗
PubMed1998

[A resected case of malignant peripheral nerve sheath tumor (MPNST) necessary to distinguish from Askin tumor].

We have treated a patient with malignant peripheral nerve sheath tumor (MPNST) for 7 years by interdisciplinary therapy. The diagnosis and treatment are reported with the clinical course so far. A 20-year-old man underwent surgical resection of a tumor on the left side of the chest in 1990, and a diagnosis of Askin tumor was made. In 1993, the disease recurred in the left axilla and was surgically resected. The surgical specimen was investigated histologically, and a diagnosis of MPNST was made instead of Askin tumor. Recently, a tumor began to grow in the left pleural cavity and was surgical resected. The tumor tissue contained both cells with oval and long spindle nuclei, which were intermingled with each other. Immunohistochemically, the tumor cells were positive for vimentin and some of them were positive for S100 protein. Because electron microscopy showed cytoplasmic processes on the tumor cell and basal lamina-like structures, a diagnosis of recurrent MPNST was made. Because this lesion resembled Askin tumor in its clinical manifestations and histological characteristics, differential diagnosis from Askin tumor was necessary. When a malignant soft tissue tumor arising from the mediastinum or chest walls is detected, immunohistochemical and electron microscopic studies should be performed. The diagnosis should be based on the overall findings including the location and clinical data.

Adult↗
PubMed1998

Ultrastructural and immunohistochemical analysis of biopsy-proven chronic active mycocarditis with numerous clusters of lymphocytes.

A 60-year-old women was admitted to our hospital with deteriorating congestive heart failure. Although the diagnosis of active myocarditis was confirmed by right ventricular endomyocardial biopsy, this patient died of refractory heart failure during corticosteroid treatment. Numerous lymphocytic clusters were observed microscopically in the heart at autopsy. Most of the infiltrating cells in the clusters were positive for CD 8, HAM 56 or MHC class 2 antigen; few cells were positive for CD 56. Expression of perforin was found in some of the infiltrating cells. Electron microscopic examination revealed small lymphocytes adhering to the surface of injured cardiac myocytes. Close contact of these lymphocytes to macrophages was shown in the clusters. ICAM-1 and MHC class 1 antigens were strongly expressed in the cardiac tissue. These results indicate that cytotoxic T lymphocyte-mediated cytotoxicity had continued to operate during immunosuppressive therapy. Corticosteroids may not be suitable for the treatment of chronic active myocarditis when persistent expression of ICAM-1 is observed.

Antibodies↗
PubMed1998

Sensitive diagnosis of cardiac allograft rejection by detection of cytokine transcription in situ.

OBJECTIVE: In situ transcription of cytokines which are important in the development of cardiac rejection has not been evaluated for diagnosing rejection. The objective was to evaluate the usefulness of in situ reverse transcriptase polymerase chain reaction (RT-PCR) for sensitive detection of acute cardiac rejection. METHODS: We studied interferon (IFN)-gamma and interleukin (IL)-2 expression using immunohistochemistry and in situ RT-PCR in murine cardiac transplant models. Hearts were heterotopically transplanted (BALB/c to C3H/He) and some mice were not treated (n = 23); others were treated with anti-intercellular adhesion molecule (ICAM)-1 and anti-lymphocyte function associated antigen (LFA)-1 monoclonal antibodies (mAbs) (n = 23). Allografts were removed at days 1 to 7. For control, isografts were harvested at day 7 (n = 2). RESULTS: Mice without treatment rejected allografts within 7 days, while all mAb-treated recipients accepted allografts for the same period. At day 1, allografts of both groups showed scattered myocardial cell infiltration which increased in non-treated allografts, but remained stable in mAb-treated grafts thereafter. In situ RT-PCR showed that IL-2 and IFN-gamma mRNA positive cells were present in non-treated allografts, while few mRNA positive cells were expressed in infiltrating cells in the mAb-treated allografts (IL-2, day 3: 88.8 +/- 28.3 vs. 7.2 +/- 6.4, p < 0.05, positive cells within 10 fields per section). However, immunohistochemistry could not reveal the difference at day 3. CONCLUSION: In situ RT-PCR is a sensitive method for diagnosing acute rejection, and it reveals the characteristics of myocardial infiltrate cells to determine their role in the process of rejection.

Animals↗
PubMed1998

Taste masking of bitter drug powder without loss of bioavailability by heat treatment of wax-coated microparticles.

Indeloxazine hydrochloride (IDX), a cerebral activator, has a bitter astringent taste. To prepare powders of IDX without this bitter taste, microparticles (median diameter, 130 microns) of IDX were coated with a mixture comprising hydrogenated oil and surfactants in a fluidized bed using the side-spray method. Drug release from the resulting coated particles was significantly delayed. Dissolution rate was remarkably enhanced, however, by heat-treating the coated particles at a temperature above the melting point of the surfactant in the coated layer. The results of differential scanning calorimetry measurements show that part of the surfactant in the coated layer exists separately. Further, surface changes in the coated layer before and after heat treatment showed that this enhancement of dissolution rate was due to rediffusion of the surfactant in the coated layer followed by melting of the surfactant. This effect allows the design of powders of IDX which release the drug quickly and with bioequivalence to the commercial IDX 20 mg tablets while sufficiently suppressing the bitter taste.

Antidepressive Agents↗
PubMed1998

Vaccine reactions.

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AIDS Vaccines↗
PubMed1998

The predictive value of quantitative nailfold capillary microscopy in patients with undifferentiated connective tissue disease.

The present prospective study was undertaken to follow the natural history of patients with Raynaud's phenomenon and to document in these patients the frequency with which secondary disorders develop. Seventeen patients with primary Raynaud's phenomenon (PRP) and 43 patients with undifferentiated connective tissue disease (UCTD) were examined after 6-8 years to see whether they had developed into UCTD or systemic sclerosis (SSc), respectively. Their nailfold capillary parameters were analysed statistically to ascertain whether they would predict for the development of the diseases into UCTD or SSc. Two patients with PRP(12%) developed into UCTD, and 10 patients with UCTD (23%) into SSc. In PRP, all three parameters of the patients who developed into UCTD showed a tendency to be larger than in those who did not develop UCTD. In UCTD, the apical limb width (P < 0.02), capillary width (P < 0.01) and capillary length (P < 0.01) of the subjects who developed SSc were significantly larger than those who did not. Of the clinicolaboratory findings in patients with UCTD, the occurrence rate of abnormal apical limb width (relative risk 20. 7, P < 0.01), abnormal capillary width (relative risk 10.7, P < 0. 01), abnormal capillary length (relative risk 9.2, P < 0.02) and antinuclear antibody (relative risk 9.6, P < 0.05) showed a significant predictive value for the development of UCTD into SSc. These results indicate that quantitative nailfold capillary microscopy, as well as antinuclear antibody, will provide exact predictive information in patients with UCTD in clinical practice.

Adolescent↗
PubMed1998

Elevated expression of epidermal ornithine decarboxylase mRNA in scleroderma.

Using in situ hybridization techniques, we examined the expression of ornithine decarboxylase (ODC) mRNA in the skin of five patients with systemic sclerosis (SSc) and five normal controls. Sections treated with an anti-sense probe showed concentrated grains exclusively in the epidermis of SSc patients, but not in that of normal controls. Because our subcloned anti-sense probe specifically hybridizes with ODC mRNA, these findings indicate that the expression of ODC mRNA is elevated in SSc epidermis. Possibly polyamines have an important part to play in the skin changes of SSc.

Humans↗