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T Sano

Publications and source records attributed to T Sano.

At least 235 records · Page 13Linked to original sources
PubMed1998

Genetic engineering of streptavidin, a versatile affinity tag.

Streptavidin, a tetrameric protein produced by Streptomyces avidinii, has been used as a useful, versatile affinity tag in a variety of biological applications. The efficacy of streptavidin is derived from its extremely high binding affinity for the vitamin biotin. For the last several years, we have used genetic engineering as a primary means to enhance the properties of streptavidin and to expand the application of streptavidin as an affinity tag. In this review, we describe several genetically engineered streptavidin variants, which include a streptavidin with a reduced biotin-binding affinity, a dimeric streptavidin, and a fusion protein between streptavidin and protein A, along with their potential applications in biological science.

Affinity Labels↗
PubMed1998

Highly restricted T cell repertoire shaped by a single major histocompatibility complex-peptide ligand in the presence of a single rearranged T cell receptor beta chain.

The T cell repertoire is shaped by positive and negative selection of thymocytes through the interaction of alpha/beta-T cell receptors (TCR) with self-peptides bound to self-major histocompatibility complex (MHC) molecules. However, the involvement of specific TCR-peptide contacts in positive selection remains unclear. By fixing TCR-beta chains with a single rearranged TCR-beta irrelevant to the selecting ligand, we show here that T cells selected to mature on a single MHC-peptide complex express highly restricted TCR-alpha chains in terms of Valpha usage and amino acid residue of their CDR3 loops, whereas such restriction was not observed with those selected by the same MHC with diverse sets of self-peptides including this peptide. Thus, we visualized the TCR structure required to survive positive selection directed by this single ligand. Our findings provide definitive evidence that specific recognition of self-peptides by TCR could be involved in positive selection of thymocytes.

Amino Acid Sequence↗
PubMed1998

Abrogation of autoimmune diabetes in nonobese diabetic mice and protection against effector lymphocytes by transgenic paracrine TGF-beta1.

Paracrine effect of transforming growth factor-beta1 (TGF-beta1) on autoimmune insulitis and diabetes was studied by transgenic production of the active form of porcine TGF-beta1 (pTGF-beta1) in pancreatic islet (islet) alpha cells in nonobese diabetic (NOD) mice under the control of rat glucagon promoter (RGP) (NOD-RGP-TGF-beta1). None of 27 NOD-RGP-TGF- beta1 mice developed diabetes by 45 wk of age, in contrast to 40 and 71% in male and female nontransgenic mice, respectively. None of the NOD-RGP-TGF-beta1 mice developed diabetes after cyclophosphamide (CY) administration. Adoptive transfer of splenocytes of NOD-RGP-TGF-beta1 mice to neonatal NOD mice did not transfer diabetes after CY administration. Adoptive transfer of three types of diabetogenic lymphocytes to NOD-RGP-TGF-beta1 and nontransgenic mice after CY administration led to the lower incidence of diabetes in NOD-RGP-TGF-beta1 mice versus that in nontransgenic mice: 29 vs. 77% for diabetogenic splenocytes, 25 vs. 75% for islet beta cell-specific Th1 clone cells, and 0 vs. 50% for islet beta cell-specific CD8(+) clone cells, respectively. Based on these, it is concluded that autoimmune diabetes in NOD mice is not a systemic disease and it can be completely prevented by the paracrine TGF-beta1 in the islet compartment through protection against CD4(+) and CD8(+) effector lymphocytes.

Adoptive Transfer↗
PubMed1998

Regional ventricular systolic abnormalities caused by a rudimentary chamber in patients with univentricular hearts.

Previous studies have demonstrated that regional wall motion abnormalities are common in univentricular hearts; however, the mechanism of this abnormality and its relation to hemodynamics remain unclear. The aim of this study was to document and analyze the etiology of regional wall motion abnormality and its relation to hemodynamics in univentricular hearts. Sixteen patients (age 11+/-6 years) were examined. A tagged cine magnetic resonance imaging method that superimposes "tags" on myocardium was used to assess regional systolic motion. The tags were traced from end-diastole to end-systole, and the percent regional shortening fraction was calculated as the shortening ratio. The tags were positioned on 6 segments. Normal ranges for wall motion were established from 10 normal volunteers. An asynchrony index was calculated as the SD divided by the mean regional shortening fraction to quantify asynchronous regional motion. Hemodynamic parameters were also obtained by cardiac catheterization. In patients, regional shortening fraction was significantly lower in segments adjacent to the rudimentary chamber compared with normal values in both circumferential and longitudinal directions (p <0.05 and p <0.01, respectively). The asynchrony index was much greater in patients than in controls (62+/-25 vs 27+/-10, p <0.01). The index correlated with rudimentary chamber volume and the rudimentary/main chamber volume ratio (r = 0.58, r = 0.79, respectively). Furthermore, the index correlated with end-diastolic pressure (r = 0.82). The rudimentary chamber may play an important role in causing asynchronous regional motion, and this motion may contribute to ventricular diastolic dysfunction.

Adolescent↗
PubMed1998

Two (Z)-dehydrobutyrine-containing microcystins from a hepatotoxic bloom of Oscillatoria agardhii from Soulseat Loch, Scotland.

Two (Z)-dehydrobutyrine(Dhb)-containing microcystins, [d-Asp3, (Z)-Dhb7]microcystin-HtyR (1) and [d-Asp3, (Z)-Dhb7]microcystin-LR (2), were isolated from a hepatotoxic bloom of the cyanobacterium Oscillatoria agardhii from a freshwater lake in Scotland. The geometrical structure of the Dhb units in the microcystins was determined as Z on the basis of NOE and ROESY experiments.

Carbohydrate Sequence↗
PubMed1998

Correlation between methylation status of the p16/CDKN2 gene and the expression of p16 and Rb proteins in primary non-small cell lung cancers.

In order to clarify the frequency of p16 gene inactivation and its relationship with Rb expression, immunohistochemical analysis of p16 and Rb proteins was carried out on 82 paraffin-embedded sections of primary non-small cell lung cancers (NSCLCs). From immunohistochemical results, abnormal p16 expression was observed in 66% of NSCLCs, 80% in squamous cell carcinomas and 46% in adenocarcinomas. An inverse correlation between p16 and Rb expressions was noted. Moreover, the methylation status of the p16 gene was investigated by the methylation-specific polymerase chain reaction (MS-PCR) using 29 frozen samples of NSCLCs. MS-PCR revealed the methylation of the p16 gene in 10(34%)of 29 NSCLCs. All NSCLCs exhibiting methylation exhibited abnormal p16 expression and were positive for Rb. In NSCLCs, no difference in methylation status was observed with respect to clinico-pathological characteristics including histological subtype and tumor stage. Our results demonstrate that abnormality of p16 expression is frequent in primary NSCLCs and methylation of the promoter of the p16 gene occurs in 34% of primary NSCLCs, which might play a significant role in the inactivation of the p16 gene.

Adenocarcinoma↗
PubMed1998

Quantitative analysis of the T cell repertoire selected by a single peptide-major histocompatibility complex.

The positive selection of CD4+ T cells requires the expression of major histocompatibility complex (MHC) class II molecules in the thymus, but the role of self-peptides complexed to class II molecules is still a matter of debate. Recently, it was observed that transgenic mice expressing a single peptide-MHC class II complex positively select significant numbers of diverse CD4+ T cells in the thymus. However, the number of selected T cell specificities has not been evaluated so far. Here, we have sequenced 700 junctional complementarity determining regions 3 (CDR3) from T cell receptors (TCRs) carrying Vbeta11-Jbeta1.1 or Vbeta12-Jbeta1.1 rearrangements. We found that a single peptide-MHC class II complex positively selects at least 10(5) different Vbeta rearrangements. Our data yield a first evaluation of the size of the T cell repertoire. In addition, they provide evidence that the single Ealpha52-68-I-Ab complex skews the amino acid frequency in the TCR CDR3 loop of positively selected T cells. A detailed analysis of CDR3 sequences indicates that a fraction of the beta chain repertoire bears the imprint of the selecting self-peptide.

Animals↗
PubMed1998

Synthesis of Cycleanine Mono-N-oxides

Oxidation of cycleanine (3) with m-chloroperbenzoic acid gave two diastereomeric N-oxides (1 and 2), and their stereochemistry was unambiguously determined on the basis of spectroscopic evidence. The NMR spectra of synthetic cycleanine mono-N-oxides 1 and 2 were significantly different from those of the natural product previously reported to be cycleanine N-oxide.

Journal Article↗
PubMed1998

Viability and pathogenicity of intersubgroup viroid chimeras suggest possible involvement of the terminal right region in replication.

To investigate the structural determinants regulating viroid replication and pathogenicity, we have examined the biological properties of four chimeric viroids containing sequences derived from hop stunt (HSVd) and citrus exocortis (CEVd) viroids. The viability of each chimera--CEHS (CEVd left half + HSVd right half), HSCE (HSVd left half + CEVd right half), CE/HS-TR (CEVd + HSVd right terminal loop), and HS/CE-TR (HSVd + CEVd right terminal loop)--was tested by inoculation onto cucumber and tomato seedlings. Chimeras CEHS and HSCE were not infectious, but CE/HS-TR and HS/CE-TR replicated stably and produced disease symptoms when inoculated onto tomato or cucumber, respectively. Progeny accumulation was reduced 10-fold or more compared to that of CEVd in tomato or HSVd in cucumber. The results suggested that the TR, like the TL and P regions, forms a relatively independent structural unit that contributes to the total function of a viroid. The effect of sequences in the right terminal loop on pathogenicity appears to be indirect, modulating the efficiency of viroid replication (or accumulation) efficiency rather than symptom expression per se.

Chimera↗
PubMed1998

Dual-colour fluorescence in situ hybridization analysis of synovial sarcoma.

Mounting cytogenetic evidence indicates that synovial sarcomas, regardless of histological conformation, share the specific reciprocal chromosomal translocation t(X;18)(p11.2;q11.2). Application of dual-colour fluorescence in situ hybridization (FISH) on interphase nuclei isolated from archival paraffin-embedded material to identify the specific translocation is of diagnostic importance for pathological practice and retrospective study. Five cases of well-characterized biphasic synovial sarcomas, two monophasic fibrous synovial sarcomas, one embryonal rhabdomyosarcoma, one fibrosarcoma, and one malignant peripheral nerve sheath tumour were analysed. To visualize the translocated chromosomal fragments and their topographic relationships with centromeres of chromosomes X and 18, nuclei from each case were hybridized concurrently with chromosome X centromeric and chromosome 18 painting probes, and chromosome 18 centromeric and chromosome X painting probes, respectively. Six out of seven synovial sarcomas showed chromosomal alterations consistent with t(X;18). One biphasic synovial sarcoma had trisomy 18 and lacked the chromosomal translocation t(X;18). The other three spindle cell sarcomas and the normal control tissues showed the normal numerical and structural composition for chromosomes X and 18. It is indicated from the present study that when histological differential diagnosis is difficult, FISH would be a crucial aid in detecting a known specific chromosomal alteration and that dual-colour FISH is an efficient stable diagnostic tool for pathological research and daily diagnosis. The results also suggest that rare synovial sarcomas may lack the chromosomal translocation t(X;18). 1998 John Wiley & Sons, Ltd.

Adult↗
PubMed1998

New ferromagnetic bone cement for local hyperthermia.

We have developed a ferromagnetic bone cement as a thermoseed to generate heat by hysteresis loss under an alternate magnetic field. This material resembles bioactive bone cement in composition, with a portion of the bioactive glass ceramic component replaced by magnetite (Fe3O4) powder. The temperature of this thermoseed rises in proportion to the weight ratio of magnetite powder, the volume of the thermoseed, and the intensity of the magnetic field. The heat-generating ability of this thermoseed implanted into rabbit and human cadaver tibiae was investigated by applying a magnetic field with a maximum of 300 Oe and 100 kHz. In this system, it is very easy to increase the temperature of the thermoseed in bone beyond 50 degrees C by adjusting the above-mentioned control factors. When the temperature of the thermoseed in rabbit tibiae was maintained at 50 to 60 degrees C, the temperature at the interface between the bone and muscle (cortical surface) surrounding the material rose to 43 to 45 degrees C; but at a 10-mm distance from the thermoseed in the medullary canal, the temperature did not exceed 40 degrees C. These results demonstrate that ferromagnetic bone cement may be applicable for the hyperthermic treatment of bone tumors.

Animals↗
PubMed1998

Nitric oxide suppression reversibly attenuates mitochondrial dysfunction and cholestasis in endotoxemic rat liver.

This study aimed to examine whether nitric oxide (NO) plays a causal role in endotoxin-induced dysfunction of biliary transport. Rats were treated with intraperitoneal injection of endotoxin (O111B4, 4 mg/kg). At 2 hours, the liver was excised and perfused ex vivo with taurocholate (TC)-containing Krebs-Ringer solution under monitoring bile output and NO2 in the perfusate and tissue cyclic guanosine monophosphate (cGMP) levels as indices of NO production. The endotoxin treatment evoked a marked decrease in the bile acid-dependent bile formation concurrent with the increasing NO2 output, cGMP elevation, and a reduction of hepatic adenosine triphosphate (ATP) contents and oxygen consumption. Perfusion with 1 mmol/L aminoguanidine (AG), an inhibitor of inducible NO synthase, but not with L-nitroarginine methyl ester, an inhibitor of the constitutive form of the enzyme, significantly reversed the endotoxin-induced increment of the bile formation in concert with the recovery of oxygen consumption and ATP levels. Laser confocal microfluorography of the liver lobules using rhodamine 123 (Rh), a fluoroprobe sensitive to mitochondrial membrane potential, revealed that endotoxin elicited a significant mitochondrial dysfunction panlobularly. The AG administration reversed the endotoxin-induced decrease in mitochondrial membrane potential. Collectively, up-regulation of NO by inducible NO synthase accounts for a mechanism through which endotoxin impairs the bile formation, and its suppression serves as a therapeutic strategy for improvement of hepatobiliary function.

Animals↗
PubMed1998

Ovarian hormone-induced beta-cell hypertrophy contributes to the homeostatic control of beta-cell mass in OLETF female rat, a model of Type II diabetes.

A sexual dimorphism regarding the incidence of diabetes mellitus in OLETF rat, a model of Type II diabetes, has been reported. As a result, the effects of ovarian hormones on beta cells per se was examined by comparing the capacity of beta-cell proliferation and changes in blood glucose and plasma insulin concentrations after a 70% pancreatectomy. All female animals were randomly assigned to two protocols. The rats involved in protocol I received either a 70% pancreatectomy (Px) or a sham pancreatectomy (sham) at 6 weeks of age, along with their diabetes-resistant counterparts, female LETO rats, which served as normal controls. The rats belonging to protocol II were given an ovariectomy (Ox) at 5 weeks of age, and one week later, they were subjected to either Px or the sham operation, with/without hormone (estradiol, 50 microg/kg; testosterone, 1 mg/kg) replacement. The findings indicate that the capacity for compensatory growth of beta cells after Px was affected by both sex hormonal and genetic components, since a 70% Px resulted in sustained hyperglycaemia within the first week after surgery, but was ameliorated by an increase in beta-cell mass thereafter in the non-Ox Px OLETF rats. The Ox also caused a decline in beta-cell mass which could be improved by replacement with ovarian hormones. Not only endogenous but also replacement ovarian hormones, led to a beneficial effect on beta cells per se in OLETF female rats. This was reflected by an increased beta-cell mass accompanied by a parallel increase in plasma immunoreactive insulin concentration. The effects of ovarian hormones, however, contributed to the beta-cell hypertrophy rather than expansion of the beta-cell population to achieve glucose homeostasis, as evidenced by an increased area of individual beta-cell after Px rather than an increased BrdU-labelling index for the beta cells. The present study suggests that ovarian hormone-induced beta-cell hypertrophy may typically occur, to compensate for changes in functional demand as the results of a 70% Px in female OLETF rats.

Animals↗
PubMed1998

The incidence and characteristics of silent cerebral infarction in elderly diabetic patients: association with serum-soluble adhesion molecules.

The purpose of this study was to investigate the relationship between complications arising from silent cerebral infarction (SCI) and changes in the levels of serum-soluble adhesion molecules in 82 elderly diabetic patients aged 60 years and older. SCI was found in 43 % of the 82 patients, with incidence increasing in relation to age. The prevalence of SCI was higher in subjects with hypertension, poor metabolic control and increased fibrinolysis. The levels of soluble intercellular adhesion molecule-1 (sICAM-1), vascular cell adhesion molecule-1 (sVCAM-1) and E-selectin (sE-selectin) were higher in diabetic patients than in non-diabetic subjects (p < 0.05, p < 0.001, and p < 0.05, respectively). Also, sICAM-1 and sVCAM-1 were found at increased levels in diabetic patients with SCI compared to those without SCI (p < 0.01 and p < 0.05, respectively). In particular, the level of sICAM-1 was increased in patients with SCI due to perforating arterial occlusion, while the level of sVCAM-1 was increased in patients with SCI due to cortical arterial occlusion. However, no significant difference was found in sE-selectin levels. Overall average of the intima and media thickness (IMT) of the common carotid arteries increased with age. IMT proved to be greater in patients with SCI than in patients without SCI (p < 0.05), and showed a weak but significant positive correlation with sVCAM-1, while no correlation was found with either sICAM-1 or sE-selectin levels. In conclusion, measurement of serum adhesion molecules may be useful for diagnosing the early stages of brain damage and for prophylactic treatment which may prevent the onset or progression of SCI.

Aged↗
PubMed1998

Oxidative stress measurement by in vivo electron spin resonance spectroscopy in rats with streptozotocin-induced diabetes.

Enhanced oxidative stress in diabetic patients may contribute to the pathogenesis of diabetic angiopathy. We have recently developed a method to determine the electron spin resonance (ESR, electron paramagnetic resonance; EPR) of reactive oxygen species and free radicals in vivo, using the nitroxide derivative, carbamoyl-PROXYL as a probe. In this study, diabetes was induced in Wistar rats by streptozotocin (STZ) injection (65 mg/kg, body weight, intravenously). Two, 4, and 8 weeks later, the animals received carbamoyl-PROXYL (300 nmol/g, intravenously), and ESR was measured at the upper abdominal level at a frequency of 300 MHz. The intensity of the carbamoyl-PROXYL ESR signal decreased gradually after the injection, and the spin clearance rate was determined over the first 5 min. At all time points, the spin clearance rate was significantly greater in the diabetic rats than in control rats. Moreover, the spin clearance rate in the diabetic rats was significantly correlated with urinary malondialdehyde (MDA) levels, which serve as a marker for lipid peroxidation. Daily treatment with 4 units neutral protamin Hagedorn (NPH) insulin for 4 weeks reduced the spin clearance rate in the diabetic rats. Simultaneous injection of carbamoyl-PROXYL and superoxide dismutase reduced the spin clearance rate in the diabetic rats in a dose-dependent manner. Injection of the antioxidant alpha-tocopherol (40 mg/kg, intraperitoneally) for 2 weeks restored the spin clearance rate in the diabetic rats without concomitant glycaemic restoration. These results suggest that a diabetic state enhances the generation of free radicals in vivo, and that both glycaemic control and antioxidant treatment can reduce this oxidative stress. Non-invasive in vivo ESR measurement may be useful for evaluating oxidative stress in diabetes.

Animals↗
PubMed1998

Expression status of p16 protein is associated with human papillomavirus oncogenic potential in cervical and genital lesions.

The p16 protein (p16) is a cyclin-dependent kinase (CDK) inhibitor that decelerates the cell cycle by inactivating the CDKs that phosphorylate retinoblastoma (Rb) protein. Recent biological studies have revealed that p16 expression is markedly influenced by the status of Rb expression, and p16 overexpression has been demonstrated in cervical cancers because of functional inactivation of Rb by human papillomavirus (HPV) E7 protein. To clarify the relationship between p16 overexpression and HPV infection in cervical carcinogenesis, immunohistochemical analysis of p16 and detection of HPV by in situ hybridization and polymerase chain reaction were performed on 139 formalin-fixed and paraffin-embedded samples of cervical and genital condylomatous and neoplastic lesions. Marked overexpression of p16 protein, ie, diffuse and strong immunostaining, was observed in all cervical cancers and preneoplastic lesions with infection by high- and intermediate-risk HPVs, ie, subtypes 16, 18, 31, 33, 52, and 58. Condylomata acuminata and low-grade squamous intraepithelial lesions with infection by low-risk HPV such as HPV-6/11 showed focal and weak immunohistochemical staining for p16. Our results clearly showed that the mode of p16 expression in lesions with high- and intermediate-risk HPVs differed from its expression in lesions with low-risk HPVs and thus might be attributable to differences in functional inactivation of Rb protein by different HPVs.

Condylomata Acuminata↗
PubMed1998

A comparison between magnetic resonance imaging and pathologic findings in patients with disc displacement.

PURPOSE: This study compared the magnetic resonance imaging (MRI) and pathologic findings in patients with disc displacement without perforation. PATIENTS AND METHODS: Eleven patients and 30 asymptomatic volunteers underwent MRI using the three-dimensional (3D) fast imaging with a steady precession sequence (FISP) acquisition technique. The 11 patients (11 joints) then underwent discectomy, and the pathologic and MRI findings were compared. RESULTS: MRI (FISP-3D) examination of the temporomandibular joint in 11 patients (11 joints) showed low signal intensity in the anterior band and the intermediate zone of the disc, and high signal intensity in the posterior band of the disc and retrodiscal tissue. On microscopic examination, the anterior band and intermediate zone of the disc were found to consist of dense collagenous bundles showing mild hyaline degeneration. Myxomatous degeneration was seen in the posterior band of the disc (11 joints), and edematous change was seen in the retrodiscal tissues (seven joints). CONCLUSIONS: Pathologic changes in the disc and the retrodiscal tissues are accurately depicted by FISP-3D.

Adult↗