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Biomedical subjects

T Baba

Publications and source records attributed to T Baba.

At least 109 records · Page 6Linked to original sources
PubMed2000

Histochemical study of apoptotic epithelial cells depending on testosterone in primary cultured rat prostatic tissues.

To clarify whether apoptosis can be induced in cultured rat prostatic epithelial cells, they were investigated at various time points, depending on different concentrations of testosterone. Ventral lobes of rat prostates were cultured as small pieces of tissues up to 14 days. They were examined by anti-Fas antibody immunostaining and also compared to findings revealed by in situ end-labelling (ISEL) technique. To clarify apoptotic nuclei at high resolution, the quick-freezing and deep-etching (QF-DE) method was also used, as reported before. The localization and appearance of Fas-positive cells were detected more widely and earlier than those of ISEL-positive cells, but both label-positive localizations were closely related to each other. In addition, they were detected more often in epithelial cells cultured with low testosterone concentrations. By the QF-DE method, chromatin fibers were found to be broken in spotty parts of apoptotic nuclei. We could control the concentration of testosterone in culture medium and detect the appearance of Fas antigen in cultured prostatic epithelial cells, followed by apoptotic changes. So, Fas and Fas-ligand system is one candidate for apoptosis in the prostate glands, depending on removal of hormonal testosterone.

Animals↗
PubMed2000

Current knowledge of dystrophin and dystrophin-associated proteins in the retina.

Dramatical development of molecular genetics has been disclosing the molecular mechanism of Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD). DMD gene product, dystrophin, is a submembranous cytoskeletal protein and many dystrophin-associated proteins (DAPs) have been identified, such as utrophin, dystroglycans, sarcoglycans, syntrophins and dystrobrevins. Dystrophin and DAPs are very important proteins not only for skeletal, cardiac, or smooth muscles but also for peripheral and central nervous systems including the retina. The retina has been extensively examined to demonstrate that dystrophin and beta-dystroglycan localize at the photoreceptor terminal, and their deficiency produces the abnormal neurotransmission between photoreceptor cells and ON-bipolar cells. Dystrophin has seven isoforms in variable tissues, and the retina contains full-length dystrophin (Dp427), Dp260, and Dp71. Recent studies have demonstrated that Dp71 localizes in the inner limiting membrane (INL) and around the blood vessel, and Dp260 is expressed in the outer plexiform layer (OPL). beta-dystroglycan is also expressed in the same regions as well as dystrophin, but it remains unclear whether other DAPs are expressed in the retina or not. It is generally assumed that dystrophin functions to stabilize muscle fibers with DAPs by linking the sarcolemma to the basement membrane, but its function in the retina is totally unknown so far.

Animals↗
PubMed2000

Association of the nitric oxide synthase gene polymorphism with an increased risk for progression to diabetic nephropathy in type 2 diabetes.

A mutation of endothelial nitric oxide synthase (ecNOS)-a key enzyme of the endogenous nitrovasodilator system that is essential for the regulation of blood flow and blood pressure-may aggravate the progression to diabetic nephropathy and/or retinopathy. To investigate the association of ecNOS tandem repeat polymorphism with diabetic nephropathy, the ecNOS genotype was assessed in 82 Japanese type 2 diabetic patients without nephropathy, 94 patients with microalbuminuria, 39 patients with nephropathy, and 155 healthy control subjects. The analysis revealed that type 2 diabetic patients with nephropathy (not with microalbuminuria) were significantly different from type 2 diabetic patients without nephropathy and healthy control subjects in genotype distribution (P = 0.0423) and frequency of the ecNOS4a allele (19.2% vs. 7.3 and 7.1%, respectively; P = 0.0078). The odds ratio of progression to diabetic nephropathy in diabetic patients who carry the mutated allele is about 2.87 compared with noncarriers. The stepwise multiple regression analysis in these patients showed that hypertension (F = 9.760) and ecNOS gene polymorphism (F = 5.298) are the relevant variables for nephropathy. However, no association was found between the ecNOS4a allele and hypertension or diabetic retinopathy. These results imply that the ecNOS gene polymorphism may be associated with progression to diabetic nephropathy in Japanese type 2 diabetic patients.

Adult↗
PubMed2000

Early glottic squamous cell carcinoma. Predictive value of MR imaging for the rate of 5-year local control with radiation therapy.

PURPOSE: To evaluate MR findings in early (T1 and T2 stages) glottic carcinomas and the predictive value of MR imaging for the rate of 5-year local control with radiation therapy. MATERIAL AND METHODS: Eighty-three patients with early glottic carcinomas were prospectively examined with MR at 1.5 T. MR investigation included unenhanced T1-weighted, T2-weighted, dynamic and contrast-enhanced T1-weighted images. Three patients with presumed advanced diseases on MR were initially treated with total laryngectomy and were excluded from the study. The remaining 80 patients were treated with radiation therapy with curative intent. Tumor detectability, size and relationship to the thyroid cartilage were determined on MR images. The MR findings were then correlated with the rate of local control. RESULTS: Forty-eight of 80 lesions (60%) were detected on MR imaging. All detected lesions but 1 demonstrated increased signal on T2-weighted images. The lesions were best delineated on dynamic images (statistically significant). The 5-year local control rate with radiation therapy was 72%. Univariate analysis revealed clinical T stage, MR detectability, tumor size and relationship to the thyroid cartilage as significant predictors. Multivariate analysis revealed that the relationship to the thyroid cartilage was an independent factor. CONCLUSION: MR provides prognostic information about the results of definitive radiation therapy. To evaluate the tumor extension in lesions detected on precontrast MR images, contrast-enhanced dynamic images should be obtained.

Adult↗
PubMed2000

Dystrobrevin localization in photoreceptor axon terminals and at blood-ocular barrier sites.

PURPOSE: Dystrobrevin is a newly discovered dystrophin-associated protein with multiple sites for phosphorylation on tyrosine residues. In the present study, the cellular distribution and subcellular localization of dystrobrevin were examined in the adult rat retina, cornea, lens, iris, ciliary body, and cultured Müller cells. METHODS: Immunoblot analysis, confocal laser scanning microscopy, and immunoelectron microscopy were used to examine dystrobrevin expression. RESULTS: Immunoblot analysis showed that an approximately 87-kDa band was expressed predominantly in the lens, retina, iris and ciliary body, whereas an approximately 60-kDa band was expressed in cultured Müller cells, cornea, retina, iris, and ciliary body. Confocal microscopy demonstrated dystrobrevin in the inner limiting membrane, outer plexiform layer, and retinal pigment epithelium and around blood vessels in the retina. At the ultrastructural level, dystrobrevin was localized under cell membranes of rod spherules and cone pedicles of photoreceptor cell terminals but often was found in the cytoplasm of endothelial cells and Müller cells. Furthermore, dystrobrevin was colocalized with beta-dystroglycan in corneal endothelium; lens, iris, and ciliary epithelia; and cultured Müller cells. CONCLUSIONS: The present study demonstrates that dystrobrevin is expressed in neurons, glia, and endothelial cells in the rat retina. In addition, dystrobrevin is localized at the blood-ocular barrier sites in extraocular tissue. These data suggest that dystrobrevin plays an important role in visual function.

Animals↗
PubMed2000

[Correlation between prior coronary revascularization and perioperative cardiac events in patients for noncardiac surgery].

We evaluated the influence of interval between prior coronary revascularization and subsequent noncardiac surgery on perioperative cardiac events. We retrospectively identified 162 consecutive patients with previous revascularization procedures who had undergone noncardiac surgery. Postoperative cardiac complications occurred in 10 (6.2%) patients, cardiac death in 1 patient, and significant arrhythmia in 3 patients. These patients had higher rates of unstable angina, myocardial infarction within 3 months, cerebrovascular disease, peripheral vascular disease, renal dysfunction (Cr > or = 1.9 mg.dl-1) and higher preoperative risk scores as described by the Cleveland Clinic (P < 0.05). Also, the incidence of cardiac complications increased when noncardiac surgery was performed within 1 week of previous percutaneous transluminal coronary angioplasty (PTCA) and in more than 5 years after coronary artery bypass grafting or PTCA (P < 0.05). Although PTCA is widely accepted, especially in Japan, early lesion progression was observed during the first several days and atherosclerotic progression was apparent in more than 5 years after the procedure. Therefore, the time between coronary revascularization and noncardiac surgery, as well as atherosclerotic risk factors, is important in evaluating patients with history of previous revascularization procedures.

Aged↗
PubMed1999

Synthetic phytanyl-chained glycolipid vesicle membrane as a novel matrix for functional reconstitution of cyanobacterial photosystem II complex.

The vesicles composed of synthetic phytanyl-chained glycolipid and natural sulfoquinovosyldiacylglycerol at 9:1 molar ratio were successfully applied to functional reconstitution of photosystem II complex (PS II) from a thermophilic cyanobacterium. The synthetic glycolipid employed was one of our model archaeal diether lipids, 1, 3-di-O-phytanyl-2-O-(beta-D-maltotriosyl)glycerol. The light-induced oxygen-evolving activity of PS II reconstituted in the glycolipid vesicles was approximately 6-fold higher than that reconstituted in several phosphatidylcholine vesicles. The present results reveal the first evidence that a well-designed synthetic glycolipid is effective for the functional reconstitution of complicated and labile membrane protein complexes, such as PS II.

Cyanobacteria↗
PubMed1999

A homologue of pancreatic trypsin is localized in the acrosome of mammalian sperm and is released during acrosome reaction.

We have identified cDNA and genomic clones encoding a homologue of pancreatic trypsin, termed TESP4, as a candidate protein involved in the sperm penetration of the egg zona pellucida in mouse. The deduced amino acid sequence indicates that TESP4 is 90% identical to pancreatic trypsin. Analysis of Northern blotting and reverse transcriptase-polymerase chain reaction reveals that the mouse TESP4 gene is ubiquitously expressed in all tissues tested, including the pancreas and testis, and the transcript is present in the haploid stages of male germ cells. Moreover, immunochemical analysis of mouse cauda epididymal sperm using an affinity-purified antibody against bovine pancreatic trypsinogen shows that TESP4 is localized only in the sperm acrosome and is released during the acrosome reaction induced by calcium ionophore A23187. These findings may open a new point of view regarding the molecular mechanisms of the sperm/egg interactions, including the sperm penetration of the egg zona pellucida.

Acrosome↗
PubMed1999

Formation and characterization of planar lipid bilayer membranes from synthetic phytanyl-chained glycolipids.

The formability, current-voltage characteristics and stability of the planar lipid bilayer membranes from the synthetic phytanyl-chained glycolipids, 1, 3-di-O-phytanyl-2-O-(beta-glycosyl)glycerols (Glc(Phyt)(2), Mal(N)(Phyt)(2)) were studied. The single bilayer membranes were successfully formed from the glycolipid bearing a maltotriosyl group (Mal(3)(Phyt)(2)) by the folding method among the synthetic glycolipids examined. The membrane conductance of Mal(3)(Phyt)(2) bilayers in 100 mM KCl solution was significantly lower than that of natural phospholipid, soybean phospholipids (SBPL) bilayers, and comparable to that of 1,2-diphytanoyl-sn-glycero-3-phosphocholine (DPhPC) bilayers. From the permeation measurements of lipophilic ions through Mal(3)(Phyt)(2) and DPhPC bilayers, it could be presumed that the carbonyl groups in glycerol backbone of the lipid molecule are not necessarily required for the total dipole potential barrier against cations in Mal(3)(Phyt)(2) bilayer. The stability of Mal(3)(Phyt)(2) bilayers against long-term standing and external electric field change was rather high, compared with SBPL bilayers. Furthermore, a preliminary experiment over the functional incorporation of membrane proteins was demonstrated employing the channel proteins derived from octopus retina microvilli vesicles. The channel proteins were functionally incorporated into Mal(3)(Phyt)(2) bilayers in the presence of a negatively charged glycolipid. From these observations, synthetic phytanyl-chained glycolipid bilayers are promising materials for reconstitution and transport studies of membrane proteins.

Animals↗
PubMed1999

Procarbazine genotoxicity in the MutaMouse; strong clastogenicity and organ-specific induction of lacZ mutations.

Procarbazine, a drug used for cancer chemotherapy, is carcinogenic in rodent bioassays. We analyzed the mutagenicity of procarbazine in various organs and the clastogenicity of the drug in hematopoietic cells of the lacZ transgenic MutaMouse. This was part of the second collaborative study of the Mammalian Mutagenesis Study Group of the Japanese Environmental Mutagen Society on the transgenic mouse mutation assay. At 50 mg kg(-1), procarbazine induced micronuclei in hematopoietic cells, but it did not increase the lacZ mutant frequency (MF) in bone marrow. It was also negative in liver, testis, spleen, kidney, and lung. Five daily administrations of 150 mg kg(-1) yielded highly positive responses in the drug's target organs for carcinogenesis (lung, bone marrow, and spleen). Lower positive responses were detected in kidney, which is a minor target organ. Liver showed only a slight increase in lacZ MF and brain showed no increase. The testis MF more than doubled which suggest that procarbazine is mutagenic to germ cells. Thus, we demonstrated that procarbazine has a strong clastogenic effect in hematopoietic cells and is mutagenic in a variety organs after high dose treatment. The induced MF was especially high in procarbazine's target organs for carcinogenesis, which supports the relevance of the transgenic mouse mutation assay for the assessment of potential genotoxins in vivo.

Animals↗
PubMed1999

A porcine homolog of the major secretory protein of human epididymis, HE1, specifically binds cholesterol.

A porcine homolog of the major secretory protein of human epididymis, HE1, was for the first time purified from the porcine cauda epididymal fluid. The HE1 homolog was secreted into the epididymal fluid as a 19-kDa glycoprotein, whose sugar moiety was gradually processed to form a 16-kDa protein during transit through the epididymis. The HE1 homolog mRNA was detected only in the caput and corpus epididymis among the porcine tissues examined. The purified HE1 homolog specifically bound cholesterol with high affinity (Kd=2. 3 microM). The binding stoichiometry was determined to be 0.94 mol/mol, suggesting that 1 mol of cholesterol binds to 1 mol of the protein. It was also found that the HE1 homolog is a major cholesterol-binding protein in the porcine epididymal fluid. The possibility that the HE1 homolog is involved in the regulation of the lipid composition of the sperm membranes during the maturation in epididymis is discussed.

Amino Acid Sequence↗
PubMed1999

Self-assembly of synthetic glycolipid/water systems.

Glycolipids (amphiphiles that bear oligosaccharides as their hydrophilic headgroups) are of importance both scientifically and technically. This review describes recent advances in our understanding of the molecular correlations in phase behavior in aqueous glycolipids over the past several years. In the first part, we discuss how headgroup stereochemistry affects the phase behavior of glycolipids both in two- and three-dimensional systems. In the second part, we discuss the effects of alkyl chain structure and phase behavior of phytanyl-chained glycolipid/water systems. The physical properties of glycolipid/water systems depend strongly on the inter-headgroup interactions that are related to such factors as stereochemistry (conformation) and size of headgroups, type of sugar residues involved, alkyl chain structure, etc. Thus, apart from the conventional concept like 'hydrophilic/lipophilic balance', explicit accounts of headgroup interactions are crucial to control the particular glycolipid/water system concerned. This is in marked contrast to the conventional amphiphile/water systems where the inter-headgroup interactions are in most cases simply repulsive.

Biopolymers↗
PubMed1999

Real-time observation of acrosomal dispersal from mouse sperm using GFP as a marker protein.

We produced transgenic mouse lines that accumulate mutated green fluorescent protein (EGFP) in sperm acrosome, a membrane limited organelle overlying the nucleus. The sperm showed normal fertilizing ability and the integrity of their acrosome was easily examined in a non-invasive manner by tracing the GFP in individual 'live' sperm with fluorescent microscopy. The time required for the dispersal of acrosomal contents was demonstrated to be approximately 3 s after the onset of acrosome reaction.

Acrosome↗
PubMed1999

Effects of chicken thymic stromal cells on the growth and differentiation of thymocytes in vitro.

We examined contact-mediated effects of chicken thymic stromal cells (TSC) on thymocyte differentiation by co-cultivation of these cell populations. The primary cultures of TSC isolated from thymus mainly have consisted of epithelial cells which were polygonal in shape, possessed long processes and expressed MHC class II antigen. When thymocytes were co-cultured with TSC, 60% to 70% of thymocytes attached to TSC and some of them engulfed underneath TSC. These attached thymocytes were CD4-CD8- and CD4+CD8+ subsets and expressed alpha/beta TCRhigh or gamma/delta TCRlow. Some of the thymocytes attaching to TSC showed an increase of intracellular and nuclear density, fragmentation of cytoplasm and nuclei, and DNA fragmentation. And also, thymocytes attaching to TSC contained a higher percentage of cycling (S and G2 + M phase) cells than nonattaching cells. These results indicate that specific subsets in thymocytes selectively bind to TSC and undergo apoptotic death or proliferation because of interaction with TSC. Chicken TSC may play an important role in thymic differentiation by direct contact within the thymus as in mammals.

Animals↗
PubMed1999

Effects of cytokines from thymocytes and thymic stromal cells on chicken intrathymic T cell development.

We have studied the ability of thymic stromal cells (TSC) and thymocytes to produce cytokines and the involvement of cytokines in intrathymic T cell development. When thymocytes were co-cultured with thymic stromal cells in absence of direct contact and mitogenic stimulation, induction of thymocyte proliferation was observed. Supernatants of cultured stromal cells (TSC-CS) promoted a high proliferative response on CD3- thymocytes but had little effect on CD3+ thymocytes. These results indicate that stromal cells have produced a cytokine which can induce immature thymocyte proliferation. Moreover, stromal cells express the MRNA for stem cell factor (SCF) and c-kit (the receptor for SCF) was detected on CD3- thymocytes but not on CD3+ thymocytes. Since SCF can enhance the proliferation of immature thymocytes in synergy with IL-7 in mammals, there is a possibility that chicken stromal cells may produce a IL-7-like factor. Thymocytes have clearly expressed interferon (IFN)-gamma. In contrast, thymic stromal cells showed no detectable expression of IFN-gamma. CD3+ thymocytes express IFN-gamma MRNA more strongly than CD3 thymocytes, suggesting that IFN-gamma from thymocytes may operate on stromal cells and then may indirectly induce clonal elimination of CD3+ cells on stromal cells. The expression of these cytokines and receptors by thymic stromal cells and thymocyte subpopulations suggests that these cytokines participate in paracrine interactions between these cell populations during thymocyte differentiation.

Animals↗