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Biomedical subjects

Y Shibata

Publications and source records attributed to Y Shibata.

At least 199 records · Page 11Linked to original sources
PubMed1998

Real-time observation of conformational fluctuations in Zn-substituted myoglobin by time-resolved transient hole-burning spectroscopy.

Equilibrium fluctuations of the protein conformation have been studied in myoglobin by a novel method of time-resolved transient hole-burning spectroscopy over a temperature range of 180-300 K and a time range of 10 ns to 10 ms. The temporal shift of the hole spectrum has been observed in a wide temperature region of 200-300 K. It has been found that the time behavior of the peak position of the hole is highly nonexponential and can be expressed by a stretched exponential function with a beta value of 0.22. As compared with the results for a dye solution sample, the time scale of the fluctuation of the protein conformation is much more weakly dependent on temperature. The time scale of the observed conformational dynamics shows a temperature dependence similar to that associated with the ligand escape process of myoglobin.

Biophysical Phenomena↗
PubMed1998

Stimulatory effect of interleukin-6 on plasminogen activator activity from human dental pulp cells.

The plasminogen activator (PA)-plasmin proteolytic system has recently received considerable attention because of its participation in a wide variety of biological activities and in pathological conditions involving tissue destruction. We examined the effects of interleukin-6 (IL-6) on PA activity and the gene expressions of tissue type (t) PA and PA inhibitor-1 (PAI-1) in human dental pulp (HDP) cells. IL-6 treatment induced significantly high PA activity in the HDP cells in a time- and dose-dependent manner, compared with nontreated controls. Western-blot analysis showed that tPA protein in the conditioned medium was stimulated by IL-6, compared with the control. The tPA and PAI-1 mRNA levels were increased in HDP cells treated with IL-6, as shown by reverse transcriptase-polymerase chain reaction. These results suggest that IL-6 stimulated PA activity through an enhancement of tPA gene expression and may be involved in extracellular matrix degradation through the stimulation of the PA-plasmin system of HDP cells.

Blotting, Western↗
PubMed1998

Analysis of HLA class II and TAP alleles in Japanese patients with psoriasis vulgaris.

We investigated HLA class II and transporter associated with antigen processing (TAP) alleles in eighty-five unrelated Japanese patients with psoriasis vulgaris and fifty-two healthy controls using the polymerase chain reaction-restriction fragment length polymorphism method. The frequencies of DRB1*1502 and DQB1*0601 were increased in the patient group (DRB1*1502; 21% vs 12%, p < 0.05, DQB1*0601; 35% vs. 21%, p < 0.05), while the frequencies of DRB1*0406 and TAP2*E were decreased in the patients (DRB1*0406; 2% vs 9%, p < 0.05, TAP2*E; 4% vs 11%, p < 0.05). However, none of these remained significant after p values were corrected for the number of comparisons made (pc > 0.05). We also analysed specific amino acids on HLA class II molecules, but no significant difference was found between the two groups. Our previous reports clarified that aspartate at residue 9 (48% vs 20%, p < 0.002) and alanine at residue 73 (81% vs 48%, p < 0.0001) on HLA-C molecules were strongly associated with Japanese patients with PsV. These specific amino acids on HLA-C molecules are supposed to play more important roles compared with HLA class II and TAP alleles in the development of psoriasis vulgaris.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1998

Detection of the apoptosis-suppressing oncoprotein bcl-2 in salivary gland lymphoma.

The bcl-2 proto-oncogene encodes an inner mitochondrial membrane protein that blocks apoptosis and programmed cell death in human lymphoid tissue. In this study a monospecific anti-human bcl-2 antibody that is reactive in formalin-fixed tissues was used with an avidin-biotin complex immunoperoxidase method to evaluate 41 cases of lymphoproliferative disorders of the salivary gland. The study cases were 26 primary salivary gland lymphomas (including 21 B-cell lymphomas four T-cell lymphomas and one true histiocytic lymphoma) and 15 cases of myoepithelial sialadenitis. Bcl-2 expression is restricted to the mantle zone and interfollicular lymphocytes around reactive germinal centers of myoepithelial sialadenitis. Seventeen of the 21 B-cell lymphomas were positive for bcl-2, and were composed of mucosa-associated lymphoid tissue (MALT), centrocytic, centroblastic-centrocytic and centroblastic lymphomas. Noticeably, all 11 cases of MALT lymphoma were bcl-2 positive. In contrast, staining for bcl-2 was present in only one of four cases of T-cell lymphomas and was negative in one true histiocytic lymphoma. The expression of bcl-2 protein was also investigated in the ductal systems and epimyoepithelial islands of salivary glands from patients with malignant lymphoma and myoepithelial sialadenitis. While salivary ducts in eight of 15 cases of myoepithelial sialadenitis immunostained for bcl-2, epimyoepithelial islands showed bcl-2 expression in only five cases of myoepithelial sialadenitis. We found that ductal cells in the salivary gland from patients with primary non-Hodgkin's lymphomas expressed bcl-2 protein. It was of interest that epimyoepithelial islands in all cases of MALT lymphoma displayed bcl-2 expression whereas other subtypes of B-cell lymphoma, T-cell lymphoma and true histiocytic lymphoma were invariably negative. These results indicate that bcl-2 is expressed in a wide variety of non-Hodgkin's lymphomas, especially when all 11 cases of MALT lymphoma are bcl-2 positive. Epimyoepithelial islands in MALT lymphoma express this oncoprotein, and their ability to induce bcl-2 synthesis resulted in the prevention of apoptosis and prolonged cell survival. Furthermore, the expression of bcl-2 protein in the lymphoma cells may be responsible for the induction of bcl-2 expression in the adjacent epimyoepithelial islands through a lymphocyte chemical mediator.

Apoptosis↗
PubMed1998

An alternatively spliced gene encoding a Y-box protein showing maternal expression and tissue-specific zygotic expression in the ascidian embryo.

An ascidian Y-box protein gene was cloned, designated as CiYB, which consists of a highly conserved cold shock domain and an auxiliary tail domain with alternating modules of acidic and basic amino acids. CiYB is a single copy gene in the ascidian genome. During oogenesis and early development, CiYB produces three different transcripts (CiYB1, CiYB2 and CiYB3) by alternate splicing. CiYB1 and CiYB2 were expressed during oogenesis, suggesting that they are recruited into maternal ribonucleoprotein particles. According to gel mobility shift assay, the CiYB1 protein has the ability to bind RNA. The sequence preference of RNA binding is similar to that of the Xenopus Y-box protein (FRGY2), which is a major component of the maternal messenger ribonucleoprotein particles (mRNP) in the oocyte. These results suggest that the ascidian Y-box protein may have an important role for masking and translational regulation of maternal mRNA. Furthermore, CiYB1, CiYB2 and CiYB3 were expressed zygotically in a tissue restricted manner. CiYB1 was expressed specifically in muscle precursor blastomeres and tail muscle cells suggesting its important role in muscle differentiation.

Age Factors↗
PubMed1998

Characterization of heparinase from an oral bacterium Prevotella heparinolytica.

Heparinase was purified to homogeneity from the cell extract of an oral bacterium, Prevotella heparinolytica, by a combination of anion exchange chromatography, gel filtration chromatography, and hydroxyapatite chromatography. Properties of the purified P. heparinolytica heparinase (P. heparinase) were investigated. The enzyme exhibited a maximum activity in 50 mM Tris-HCl buffer, pH 7.5-8.0, containing 75 mM sodium acetate, 0.1 M NaCl, and 1 mM CaCl2. Optimum conditions for the maximum activity of P. heparinase were similar to those of the heparinase from Flavobacterium heparinum (F. heparinase). The two enzymes also yielded similar digestion profiles of various glycosaminoglycans and heparin tetrasaccharides, suggesting that they have a similar substrate specificity. Kinetic study of the P. heparinase reaction using porcine intestinal heparin as substrate gave a Km value of 3.8 x 10(-5) M and a Vmax value of 11.4 micromol/min x mg protein. The Michaelis constant of P. heparinase was slightly larger than but not significantly different from that of F. heparinase. The amino acid composition of P. heparinase was also similar to that of F. heparinase, but its N-terminal sequence of 20 amino acid residues was different and hitherto unreported. These results together indicate that these heparinases are different proteins with closely similar enzymatic properties. Since F. heparinum produces not only heparinase but also heparitinase II, which has a broad substrate specificity, F. heparinase may be contaminated with this enzyme. In contrast, P. heparinolytica does not produce heparitinase II, and P. heparinase should prove a useful tool for degrading heparin without the risk of contamination with heparitinase II.

Amino Acid Sequence↗
PubMed1998

Reconstruction of nasal tip defects by dorsonasal V-Y advancement island flap.

The nasalis musculocutaneous sliding flap developed by Rybka and the myocutaneous axial flap with lateral pedicle reported by Martire and associates are extremely useful for reconstruction of the nasal tip and surrounding area, respectively. We have modified the method of Martire and associates into an operative procedure that can be easily employed. By confirming the blood flow of the lateral nasal artery preoperatively by Doppler probing, the lateral pedicle of the flap was made smaller to facilitate mobilization of the flap. Furthermore, this flap could be made into a reversed-flow flap when indicated.

Adolescent↗
PubMed1998

Influence of degree of carotid artery stenosis and collateral pathways and effect of carotid endarterectomy on cerebral vasoreactivity.

OBJECTIVE: The goal was to determine the influence of the degree of internal carotid artery (ICA) stenosis and collateral pathways on cerebral vasoreactivity (CVR). The effect of carotid endarterectomy on CVR is also presented. METHODS: For 36 patients with unilateral ICA stenosis of at least 70%, regional cerebral blood flow (rCBF) and regional CVR (rCVR) were investigated before and after carotid endarterectomy, with resting and acetazolamide-challenge single photon emission computed tomographic scans. The degree of ICA stenosis and the status of the collateral pathways (sizes of the A1 segment and the posterior communicating artery) were evaluated by angiography. RESULTS: Thirteen patients were classified as Type N/N (normal rCBF and normal rCVR), 5 as Type R/N (reduced rCBF and normal rCVR), 6 as Type N/R (normal rCBF and reduced rCVR), and 12 as Type R/R (reduced rCBF and reduced rCVR). The degree of ICA stenosis correlated with rCVR status. The size of the A1 segment was a second-rank factor and was less effective in affecting rCVR. The size of the posterior communicating artery was not associated with rCVR. The predictive value of reduced rCVR for postoperative improvement (100%) was significantly higher than that of reduced rCBF (50%). CONCLUSION: The present results indicate that the degree of ICA stenosis is a more significant determinant of CVR than are the collateral pathways in patients with carotid artery stenosis. The high predictive rate of reduced rCVR for postoperative improvement implies that acetazolamide-challenge single photon emission computed tomographic scanning might be useful in selecting patients with asymptomatic ICA stenosis who might benefit from carotid endarterectomy.

Acetazolamide↗
PubMed1998

Manganese-metalloporphyrin (ATN-10) as a tumor-localizing agent: magnetic resonance imaging and inductively coupled plasma atomic emission spectroscopy study with experimental brain tumors.

OBJECTIVE: We examined whether selective tumor accumulation of a novel manganese-metalloporphyrin (ATN-10) occurs in Fisher rats bearing intracerebral 9L gliomas. METHODS: After intravenous administration of ATN-10, magnetic resonance imaging of brains with tumors or nontumoral vasogenic brain edema was performed. Tissue manganese concentrations were measured by inductively coupled plasma atomic emission spectroscopy until 48 hours after administration of ATN-10, to evaluate its uptake in tumor, normal brain, and peritumoral brain tissue. RESULTS: In magnetic resonance imaging scans, early enhancement was observed in both tumor tissue and regions of nontumoral vasogenic brain edema at 5 minutes after ATN-10 administration. However, delayed enhancement was noted only in tumor tissue, at 24 hours after intravenous injection of ATN-10. Comparison of rat brain specimens and 24-hour magnetic resonance imaging scans revealed that only the viable portions of tumors were enhanced with ATN-10; necrotic regions and areas of peritumoral brain tissue and nontumoral vasogenic edema were not. Significantly greater uptake of ATN-10 was found in tumor samples, compared with normal and peritumoral brain tissue, at 24 hours. A high tumor/normal brain tissue ratio (10.4) was achieved at 24 hours. CONCLUSION: ATN-10, a manganese-metalloporphyrin, is a potentially useful tumor-localizing agent that accumulates and is preferentially retained in viable tumor tissue.

Animals↗
PubMed1998

Treatment of subdural effusion with hydrocephalus after ruptured intracranial aneurysm clipping.

OBJECTIVE: This study was conducted to determine whether a ventriculoperitoneal shunt alone was effective in treating subdural effusion with hydrocephalus. METHODS: Using only a ventriculoperitoneal shunt, we successfully treated eight patients who had subdural effusion with hydrocephalus after ruptured intracranial aneurysmal clipping, despite ventricular deformity and midline shift. RESULTS: For all of the patients, both the subdural effusion and ventriculomegaly subsided and clinical symptoms lessened after surgery. CONCLUSION: Ventriculoperitoneal shunting alone is an effective and satisfactory procedure; no subdural peritoneal shunt is needed for patients with subdural effusion accompanied by hydrocephalus. To-and-fro communication between the subdural effusion and ventricles is considered to be present in these patients. When selecting the treatment for subdural effusion, it is important to consider whether hydrocephalus (disturbance of cerebrospinal fluid circulation) is present.

Adult↗
PubMed1998

Purification and properties of a bacteriocin of Staphylococcus epidermidis isolated from dental plaque.

An extracellular bacteriocin of Staphylococcus epidermidis isolated from dental plaque was purified and characterized. Its molecular mass was 3500 Da and pI was 10.5. This bacteriocin inhibited the growth of Staphylococcus aureus, Streptococcus salivarius, and Streptococcus mitis, but Streptococcus mutans, Streptococcus sanguis and other oral indigenous bacterial species examined were not inhibited. The mode of inhibition was found to be bacteriostatic.

Bacterial Proteins↗
PubMed1998

Endoscopic diagnosis of lower intestinal lesions of leukaemia and malignant lymphoma.

There have been only a few endoscopic studies with respect to lower intestinal lesions of leukaemia and malignant lymphoma, although there have been many autopsy studies of these lesions. The aim of this study was to clarify these lesions using endoscopy. Colonoscopy was performed on 11 of 341 patients with leukaemia and on 32 of 105 patients with malignant lymphoma for frequent diarrhoea, anal bleeding or abnormal findings on barium enema examination, between April 1984 and September 1994. In eight of the 11 patients with leukaemia on whom endoscopy was performed, nine lesions were found; aphthoid ulcers, small ulcers or large tumours due to leukaemic infiltration were found in five, and colorectal adenoma was found in only one patient. Antibiotic-associated haemorrhagic colitis or pseudomembranous colitis was found in one patient each. In 10 of the 32 patients with malignant lymphoma, 11 lesions were found. The following were found in one patient each: large lymphomatous tumours, a large lymphomatous ulcer, multiple small polypoid lesions, multiple lymphomatous polyposis; and colorectal cancer or adenoma in six patients. However, the autopsy findings in patients with both diseases were mostly pseudomembrane formation or ulcers due to fungal and/or bacterial infection. It is concluded that accurate endoscopic diagnosis of lower intestinal lesions in patients with leukaemia or malignant lymphoma is essential for staging and treatment of these diseases and for determining their prognosis. Most lesions in leukaemia are aphthoid and small ulcers are due to leukaemic infiltration or antibiotics; most lesions in malignant lymphoma are elevated lesions such as cancer, adenoma or lymphomatous lesions as determined by endoscopy. This is in contrast to pseudomembrane formation or ulcers due to fungal and/or bacterial infection which are detected at autopsy.

Adult↗
PubMed1998

Immunotherapy before and during pregnancy improves pregnancy outcome in women who suffer from recurrent abortion and did not benefit from immunotherapy before pregnancy.

PROBLEM: The appropriate modality of immunotherapy with the husband's mononuclear cells in women with a history of recurrent abortion who aborted despite the immunotherapy performed before pregnancy was explored. METHOD OF STUDY: Nineteen patients who had suffered from recurrent abortion who had received the immunotherapy only before pregnancy and had aborted were treated with further immunotherapy performed either only before pregnancy or twice: before and during pregnancy. RESULTS: In 9 out of the 19 women who received further immunotherapy before pregnancy, 2 had healthy babies and 7 aborted again. In the remaining 10 patients who received further immunotherapy twice, before and during pregnancy, 8 had healthy babies and 2 aborted again. CONCLUSION: Our results indicate that immunotherapy performed before and during pregnancy produces a better outcome compared with that performed only before pregnancy, especially in patients who showed no benefit from the immunotherapy performed only before pregnancy.

Abortion, Habitual↗
PubMed1998

Secretion of interleukin-2 from unstimulated peripheral blood mononuclear cells is a possible pathogenic mechanism in recurrent abortion.

PROBLEM: The objective of this study was to evaluate the activated status of helper T cells in women with recurrent abortion. METHOD OF STUDY: The spontaneous secretion of interleukin (IL)-2 from peripheral blood mononuclear cells (PBMCs) obtained from 12 women with primary partner-specific recurrent abortion and 7 normal females and 10 normal males was measured. RESULTS: IL-2 concentrations in medium conditioned with PBMCs from the recurrent abortion group were 1.44 +/- 0.32 (mean +/- standard deviation) U/ml, whereas those from the normal female and male groups were below the minimum detectable concentration. CONCLUSION: The fact that PBMCs from recurrent aborters spontaneously secrete IL-2 suggests that helper T cells are activated in recurrent aborters.

Abortion, Habitual↗
PubMed1998

Construction of a functional single-chain variable fragment antibody against hemagglutinin from Porphyromonas gingivalis.

Hemagglutinin is a major glycoprotein of Porphyromonas gingivalis vesicles and likely confers the ability to adsorb and penetrate into host tissue cells. To protect this bacterial invasion, murine monoclonal antibody (MAb) Pg-vc, which inhibited the hemagglutinating activity, was prepared by using P. gingivalis vesicles as an antigen. Western blot analysis revealed that when both MAb Pg-vc and anti-HA-Ag2 antibody raised against the P. gingivalis hemagglutinin adhesin (M. Deslauriers and C. Mouton, Infect. Immun. 60:2791-2799, 1992) were allowed to react with protein blots from P. gingivalis vesicles, a superimposable profile was observed. To obtain a recombinant antibody, cDNAs coding for the variable domains of the L and H chains of MAb Pg-vc were cloned by PCR, and a plasmid specifying a single-chain variable fragment (ScFv) was constructed. Following transformation of Escherichia coli cells, a recombinant ScFv protein was successfully expressed. The immunological properties of this protein were identical to those of the parental murine MAb, specifically recognizing the two proteins (43 and 49 kDa) originating from P. gingivalis vesicles. In addition, the ScFv antibody inhibited the P. gingivalis vesicle-associated hemagglutinating activity. The amino acid sequences deduced from nucleotide sequencing experiments confirmed that variable heavy-chain and variable light-chain regions belonged to VH1 and Vkappa12/13 families, respectively. Since the expression system used in this study can readily provide large quantities of single-chain recombinant antibody, it may be a useful in developing a therapeutic agent for passive immunization in humans.

Amino Acid Sequence↗
PubMed1998

Identification of Bombyx mori midgut receptor for Bacillus thuringiensis insecticidal CryIA(a) toxin.

As part of a study of the mechanism by which Bacillus thuringiensis insecticidal crystal protein acts, a Bombyx mori receptor to the CryIA(a) toxin specific for lepidopterans was examined. Histological examination showed that the toxin acted on the brush-border membrane of the midgut columnar cells and broke its infolding structure, causing cell lysis. The membrane vesicles were purified, and a 175-kDa protein binding the toxin was found that accounted for some 0.015% of membrane proteins. The protein, designated BtR175, was a glycoprotein that reacted with concanavalin A. Anti-BtR antibodies inhibited the binding of toxin to membrane vesicles in vitro and decreased the effect of the toxin to silkworms in vivo. BtR175, although found in the gut, was not found in fat bodies, integument, or silk glands. These results indicated that BtR175 was the receptor protein for the insecticidal toxin. Proteins (137 and 107 kDa) binding the CryIA(a) toxin also were found in the gut membranes of Tenebrio moritor larvae, a coleopteran not sensitive to the toxin. The specificity of the toxin could not be explained only in term of the existence of its binding protein.

Animals↗