Biomedical subjects

T Hoshino

Publications and source records attributed to T Hoshino.

At least 37 records · Page 2Linked to original sources

PubMed2001

CIS3/SOCS3/SSI3 plays a negative regulatory role in STAT3 activation and intestinal inflammation.

Immune and inflammatory systems are controlled by multiple cytokines, including interleukins (ILs) and interferons. These cytokines exert their biological functions through Janus tyrosine kinases and signal transducer and activator of transcription (STAT) transcription factors. We recently identified two intrinsic Janus kinase (JAK) inhibitors, JAK binding protein (JAB; also referred to as suppressor of cytokine signaling [SOCS1]/STAT-induced STAT inhibitor [SSI1]) and cytokine-inducible SH2 protein (CIS)3 (or SOCS3/SSI3), which play an essential role in the negative regulation of cytokine signaling. We have investigated the role of STATs and these JAK inhibitors in intestinal inflammation. Among STAT family members, STAT3 was most strongly tyrosine phosphorylated in human ulcerative colitis and Crohn's disease patients as well as in dextran sulfate sodium (DSS)-induced colitis in mice. Development of colitis as well as STAT3 activation was significantly reduced in IL-6-deficient mice treated with DSS, suggesting that STAT3 plays an important role in the perpetuation of colitis. CIS3, but not JAB, was highly expressed in the colon of DSS-treated mice as well as several T cell-dependent colitis models. To define the physiological role of CIS3 induction in colitis, we developed a JAB mutant (F59D-JAB) that overcame the inhibitory effect of both JAB and CIS3 and created transgenic mice. DSS induced stronger STAT3 activation and more severe colitis in F59D-JAB transgenic mice than in their wild-type littermates. These data suggest that hyperactivation of STAT3 results in severe colitis and that CIS3 plays a negative regulatory role in intestinal inflammation by downregulating STAT3 activity.

Animals↗

PubMed2001

The restricted expression of granzyme M in human lymphocytes.

We have analyzed the expression of human granzyme M (Gzm M) in various human leukocyte subsets using the specific mAb 4H10. Using FACS and Western blotting analysis we compared the expression of Gzm M with that of other granzymes (Gzm A and Gzm B) and the lytic protein perforin. Human Gzm M was constitutively highly expressed in NK cells as was perforin and Gzm A. Surprisingly, freshly isolated NK cells had very low (sometimes undetectable) levels of Gzm B. In contrast to Gzm B and perforin, Gzm M was not detected in highly purified CD4(+) and CD8(+) T cells either constitutively or after short term activation in vitro. However, low levels of Gzm M were observed in some T cell clones on prolonged passage in vitro. Gzm M was not detected in highly purified neutrophils, monocytes, or tumor cells of the myelomonocytic lineage. Examination of minor T cell subsets from human peripheral blood showed detectable Gzm M in CD3(+), CD56(+) T cells and gammadelta T cells. A histological staining procedure was developed that demonstrated a granular staining pattern for Gzm M and a cellular distribution similar to that observed by Western blotting. These data indicate that the expression of Gzm M does not always correlate with the lytic activity of cytotoxic cells. However, expression of Gzm M in NK cells, CD3(+), CD56(+) T cells, and gammadelta T cells suggests that this enzyme may play some role in innate immune responses.

Blotting, Western↗

PubMed2001

NMR analysis of type III antifreeze protein intramolecular dimer. Structural basis for enhanced activity.

The structure of a new antifreeze protein (AFP) variant, RD3, from antarctic eel pout (Rhigophila dearborni) with enhanced activity has been determined for the first time by nuclear magnetic resonance spectroscopy. RD3 comprises a unique translational topology of two homologous type III AFP globular domains, each containing one flat, ice binding plane. The ice binding plane of the N domain is located approximately 3.5 A "behind" that of the C domain. The two ice binding planes are located laterally with an angle of 32 +/- 12 degrees between the planes. These results suggest that the C domain plane of RD3 binds first to the ice [1010] prism plane in the <0001> direction, which induces successive ice binding of the N domain in the <0101> direction. This manner of ice binding caused by the unique structural topology of RD3 is thought to be crucial for the significant enhancement of antifreeze activity, especially at low AFP concentrations.

Amino Acid Sequence↗

PubMed2001

Functional reconstitution and regulation of IL-18 activity by the IL-18R beta chain.

IL-18 and IL-12 are major IFN-gamma-inducing cytokines but the unique synergism of IL-18 and IL-12 remains unclear. In the human NK cell line NKO, IL-18R alpha, and IL-18R beta are expressed constitutively but IL-18 did not induce IFN-gamma unless IL-12 was present. COS-1 fibroblasts, which produce the chemokine IL-8 when stimulated by IL-1 beta or TNF-alpha, do not respond to IL-18, despite abundant expression of the IL-18R alpha chain. COS-1 cells lack expression of the IL-18R beta chain. The IL-18R beta cDNA was cloned from a human T-B lymphoblast cDNA library and COS-1 cells were transiently transfected with the IL-18R beta chain and a luciferase reporter. In transfected COS-1 cells, IL-18 induced IL-8 and luciferase in the absence of IL-12 and independently of IL-1 and TNF. Ab against the IL-18R alpha chain, however, prevented IL-18 responsiveness in COS-1 cells transfected with the IL-18R beta chain, suggesting that both chains be functional. In NKO cells and PBMC, IL-12 increased steady-state mRNA levels of IL-18R alpha and IL-18R beta; the production of IFN-gamma corresponded to IL-12-induced IL-18R alpha and IL-18R beta chains. We conclude that functional reconstitution of the IL-18R beta chain is essential for IL-12-independent proinflammatory activity of IL-18-induced IL-8 in fibroblasts. The synergism of IL-18 plus IL-12 for IFN-gamma production is, in part, due to IL-12 up-regulation of both IL-18R alpha and IL-18R beta chains, although postreceptor events likely contribute to IFN-gamma production.

Animals↗

PubMed2001

Long-term audiological feature in Pendred syndrome caused by PDS mutation.

Pendred syndrome is an autosomal recessive disorder characterized by profound deafness in childhood and goiter. We report a case of Pendred syndrome in a 27-year-old woman who had a diffuse goiter and progressive sensorineural hearing loss with fluctuation and a missense mutation (His723Arg) in the PDS gene identified in a homozygous state. Audiological findings were observed clinically over a 20-year period. Progressive hearing loss with fluctuation occurred before age 12 years. An enlarged vestibular aqueduct with enlargement of the endolymphatic duct and sac was confirmed with 3-dimensional magnetic resonance imaging hydrography.

Adult↗

PubMed2001

Sustained-release microcapsules of a bone formation stimulant, TAK-778, for local injection into a fracture site.

The benzothiepin derivative (2R,4S)-(-)-N-(4-diethoxyphosphorylmethylphenyl)-1,2,4,5-tetrahydro-4-methyl-7,8-methylenedioxy-5-oxo-3-benzothiepin-2-carboxamide (TAK-778) is a potent bone formation stimulant. A sustained release formulation was prepared by encapsulating the drug into biodegradable microcapsules for local application to fracture repair in rats. The microcapsules consisted of TAK-778 (10% w/w) and a biodegradable polymer, copoly (d,l-lactic/glycolic acid), with a copolymer ratio of 85:15 (mol/mol) and an average molecular weight of 15 k. The TAK-778 amount at the injection site progressively diminished for 4 weeks after administration, and the serum level of TAK-778 was sustained over the same period. The local concentration of TAK-778 after administration of the microcapsules was simulated by a two-compartment open model. In the model, a first-order release rate constant and a transfer rate constant were obtained from the release profile of the microcapsules and the serum level of TAK-778 after administration of the TAK-778 solution, respectively. Localization at the injection site was examined by radiography using microcapsules in which iodoform was encapsulated as a contrast agent. The microcapsules formed a clot at the injection site, and their spread was narrowly restricted. The local concentration was calculated to be maintained within the range 10(-3)-10(-6) M over 4 weeks on the assumption that the dose and spread volume were 5 mg of TAK-778/site and 3 mL, respectively.

Animals↗

PubMed2001

A novel sphingophosphonolipid head group 1-hydroxy-2-aminoethyl phosphonate in Bdellovibrio stolpii.

Members of the bacterial genus Bdellovibrio include strains that are free-living, whereas others are known to invade and parasitize larger Gram-negative bacteria. The bacterium can synthesize several sphingophospholipid compounds including those with phosphoryl bonds as well as phosphonyl bonds. In the present study, the dominant sphingophosphonolipid component was isolated by column chromatography, and the long-chain bases, fatty acids, and polar head groups were identified by thin-layer and gas-liquid chromatographic procedures. The definitive structural identity of the sphingolipid was established by nuclear magnetic resonance and mass spectrometry of hydrolysis products and the intact compound. The compound was identified as N-2'-hydroxypentadecanoyl-2-amino-3,4-dihydroxyheptadecan-1-phosphono-(1-hydroxy-2-aminoethane).

Bdellovibrio↗

PubMed2001

Theoretical studies of the ATP hydrolysis mechanism of myosin.

The ATP hydrolysis mechanism of myosin was studied using quantum chemical (QM) and molecular dynamics calculations. The initial model compound for QM calculations was constructed on the basis of the energy-minimized structure of the myosin(S1dc)-ATP complex, which was determined by molecular mechanics calculations. The result of QM calculations suggested that the ATP hydrolysis mechanism of myosin consists of a single elementary reaction in which a water molecule nucleophilically attacked gamma-phosphorus of ATP. In addition, we performed molecular dynamics simulations of the initial and final states of the ATP hydrolysis reaction, that is, the myosin-ATP and myosin-ADP.Pi complexes. These calculations revealed roles of several amino acid residues (Lys185, Thr186, Ser237, Arg238, and Glu459) in the ATPase pocket. Lys185 maintains the conformation of beta- and gamma-phosphate groups of ATP by forming the hydrogen bonds. Thr186 and Ser237 are coordinated to a Mg(2+) ion, which interacts with the phosphates of ATP and therefore contributes to the stabilization of the ATP structure. Arg238 and Glu459, which consisted of the gate of the ATPase pocket, retain the water molecule acting on the hydrolysis at the appropriate position for initiating the hydrolysis.

Adenosine Diphosphate↗

PubMed2001

Relationships of glucose concentrations in capillary whole blood, venous whole blood and venous plasma.

We studied the difference in glucose levels between capillary and venous whole blood during 75-g oral glucose tolerance test (OGTT) in 75 healthy subjects. Capillary and venous whole blood glucose values were measured by HK-G6PD method after deproteinization. The post-loaded glucose levels in capillary blood were significantly higher than those in venous blood, and the mean values of capillary and venous difference at 30, 60, 90, 120 and 180 min were 1.37, 1.40, 1.07, 0.95 and 0.52 mmol/l, respectively, with the maximum difference at 60 min. No correlation was found in the magnitude of the differences in glucose between capillary and venous blood specimens. We determined the inaccuracy of six self-monitoring blood glucose devices relative to the reference method using venous plasma, venous whole blood and capillary whole blood from 31 diabetic patients. The differences of mean values of venous whole blood and capillary whole blood, and venous whole blood and venous plasma, and capillary whole blood and venous plasma were 9.6%, 11.3% and -3.2%, respectively. The range of bias and Sy/x were 0.31-1.06 mmol/l and 0.71-1.07 mmol/l, respectively, compared to the reference method using venous plasma.

Blood↗

PubMed2001

Role of nitric oxide in focal microcirculation disorder of guinea pig cochlea.

This study was designed to evaluate the role of endogenous nitric oxide (NO) in focal microcirculation disorder of the guinea pig cochlea. Focal microcirculation disorder was induced by a photochemical reaction at the lateral wall of the second cochlear turn. Saline or N omega-nitro-L-arginine methyl ester (L-NAME) was administered before the onset of photochemical reaction. Cochlear blood flow (CBF) was measured at the focal lesion (ischemic core), 1 mm from the lesion in the apical and basal direction (ischemic border zone) by using a novel non-contact laser blood flowmeter. NO synthase activities were measured by radioenzymeassay. In the saline pretreatment group, CBF was significantly decreased to 58.8+/-4.4% of the baseline at the ischemic core 30 min after the onset of photochemical reaction (P<0.01), while CBF showed no significant change at the ischemic border zone. In the L-NAME pretreatment group, CBF was significantly decreased not only at the focal lesion (48.3+/-6.5%, P<0.01), but also at the ischemic border zone (apical, 49.3+/-2.3%, P<0.05; basal, 58.7+/-7.1%, P<0.05, respectively). NO synthase III activity of cochlea was increased significantly (P<0.01) 15 min after microcirculation disorder. These findings suggest that formation of endogenous NO plays a key role in the maintenance of CBF in acute focal cochlear microcirculation disorder.

Animals↗

PubMed2001

Prevention of postoperative complications in skull base surgery for nasal or paranasal sinus carcinoma invading the skull base.

With recent technical advances in skull base surgery, radical resection of a nasal or paranasal sinus carcinoma invading the skull base can now be achieved. To assure a satisfactory surgical result, it is essential to prevent postoperative infection. In our series of 14 cases, serious postoperative infections occurred in the earliest 10 cases, and only 2 of these patients are still alive. The vascularised abdominal muscle flap for skull base reconstruction was fixed with fibrin glue, but was not adequate to fill the dead space, resulting in cerebrospinal fluid leakage and subsequent meningitis. Once the infection occurred, a free bone flap became the focus of infection. Based on these earlier experiences, we used a ROC fastener system to completely fill the dead space with an abdominal muscle flap, and bone flap was primarily craniectomised in the four most recent cases. With this technique, there were no postoperative infections.

Abdominal Muscles↗

PubMed2001

Cold-stimulated increase in a regulatory subunit of cAMP-dependent protein kinase in human hepatoblastoma cells.

Although cold-stress responses in bacteria and plants have been well studied and hypothermic conditions are used in clinical treatments, there has been little investigation of cold-stress responses in human cells, and there has been no report on the involvement of signal transduction modulators in the cold-stress response in human cells. We therefore investigated alterations in the expression of genes involved in the signal transduction system and the mechanisms of cold-stimulated increases in the expression of genes in human hepatoblastoma (HepG2) cells. Using a cDNA expression array method, we found that a transcript encoding a regulatory subunit Ibeta (RIbeta) of cyclic AMP-dependent protein kinase (PKA) was increased in cold-stressed cells. Western blot analysis revealed that the amount of PKA RIbeta protein was increased by cold treatment, while that of a PKA catalytic subunit (C) was unchanged. The protein level of PKA RIbeta was increased in cells treated with low concentrations of actinomycin D, whereas that of PKA C was not, implying that the increase was caused by the suppression of transcription at low temperatures. In addition, degradation of the PKA RIbeta protein was not stimulated by cold treatment, unlike that of the PKA C protein. The results suggest that signal transduction through PKA also participates in cold-stress responses in human cells and that multiple mechanisms are involved in the increase in the level of the PKA RIbeta protein.

Carcinoma, Hepatocellular↗

PubMed2001

Japanese and Western diet and risk of idiopathic sudden deafness: a case-control study using pooled controls.

BACKGROUND: One of the proposed aetiological mechanisms for idiopathic sudden deafness is vascular disease. However, it is not known whether traditional cardiovascular risk factors, such as particular dietary factors, are associated with this condition. METHODS: A case-control study using pooled controls was conducted in Japan to investigate the relationship between idiopathic sudden deafness and diet. An m:n matched-pairs method was used to obtain age-, gender- and residential district-matched controls from a nationwide database of pooled controls. Food intake was assessed from a self-administered usual food frequency questionnaire that asked about intake of 35 foods (including four drinks). Participants were classified according to the frequency of intake of Western foods and the frequency of intake of traditional Japanese foods. Subgroup analyses were performed using audiometric subtypes of idiopathic sudden deafness. RESULTS: Data were obtained for 164 cases and 20,313 controls. An increased risk of sudden deafness was observed among participants who frequently consumed Western foods (OR = 1.82, 95% CI : 1.14--2.89), and a decreased risk of this condition was observed among participants who frequently consumed Japanese foods (OR = 0.52, 95% CI : 0.33--0.82). A direct association of sudden deafness with Western food intake was evident for flat-type hearing loss. CONCLUSIONS: This study suggests that a largely Western diet might be a risk factor for idiopathic sudden deafness, a traditional Japanese diet might be a preventive factor for this condition, or both. These findings are consistent with the hypothesis that vascular factors are an important cause of idiopathic sudden deafness, although the possibility of residual confounding by unmeasured confounders such as socioeconomic status cannot be ruled out.

Audiometry↗

PubMed2001

Effects of garlic preparations on the gastrointestinal mucosa.

The effects of garlic preparations, including dehydrated raw garlic powder (RGP), dehydrated boiled garlic powder (BGP) and aged garlic extract (AGE), on the gastric mucosa were determined using a newly established endoscopic air-powder delivery system, which can deliver solid materials directly into the stomach. Among the three preparations, RGP caused severe damage, including erosion. BGP also caused reddening of the mucosa, whereas AGE did not cause any undesirable effects. The safety of enteric-coated garlic products was also determined. Direct administration of pulverized enteric-coated products on the gastric mucosa caused reddening of the mucosa. When an enteric-coated tablet was administered orally, it caused loss of epithelial cells at the top of crypts in the ileum. These results suggest that caution be used with regard to safety and effectiveness when choosing a garlic preparation because some preparations may have undesirable effects, including gastrointestinal problems.

Animals↗

PubMed2001

Hypocoagulable state of human preovulatory ovarian follicular fluid: role of sulfated proteoglycan and tissue factor pathway inhibitor in the fluid.

Ovulation accompanied by tissue damage can cause an increase in the level of tissue factor (TF) in the follicular fluid, triggering the extrinsic coagulation pathway. However, follicular fluid must block fibrin formation and maintain fluidity until the release of the oocyte at ovulation. The combination of sulfated proteoglycan, antithrombin, and TF pathway inhibitor (TFPI) appears to play a critical role in the hypocoagulability of human follicular fluid. When compared with plasma, folicular fluid differs markedly in the levels of a number of important coagulation proteins. Principal among these are 15-fold, 13-fold, and 3.7-fold increases in free TFPI, thrombin-antithrombin complex, and TF, respectively. The excessively prolonged activated partial thromboplastin time (APTT) and prothrombin time (PT) of human ovarian follicular fluid appear to be primarily due to high concentrations of sulfated proteoglycans, which accelerate the inactivation of thrombin and the anti-Xa activity of TFPI. Thus, heparitinase treatment shortened the clotting times of follicular fluid and reduced the inhibition of thrombin by the proteoglycan fraction combined with a fraction containing antithrombin. The remaining prolongation of APTT and PT may be caused by high levels of free TFPI in follicular fluid, which were confirmed by Northern blotting analysis, demonstrating TFPI mRNA expression by granulosa cells.

Antithrombin III↗

PubMed2001

Direct detection by in situ PCR of the amoA gene in biofilm resulting from a nitrogen removal process.

Ammonia oxidation is a rate-limiting step in the biological removal of nitrogen from wastewater. Analysis of microbial communities possessing the amoA gene, which is a small subunit of the gene encoding ammonia monooxygenase, is important for controlling nitrogen removal. In this study, the amoA gene present in Nitrosomonas europaea cells in a pure culture and biofilms in a nitrifying reactor was amplified by in situ PCR. In this procedure, fixed cells were permeabilized with lysozyme and subjected to seminested PCR with a digoxigenin-labeled primer. Then, the amplicon was detected with an alkaline phosphatase-labeled antidigoxigenin antibody and HNPP (2-hydroxy-3-naphthoic acid-2'-phenylanilide phosphate), which was combined with Fast Red TR, and with an Alexa Fluor 488-labeled antidigoxigenin antibody. The amoA gene in the biofilms was detected with an unavoidable nonspecific signal when the former method was used for detection. On the other hand, the amoA gene in the biofilms was detected without a nonspecific signal, and the cells possessing the amoA gene were clearly observed near the surface of the biofilm when Alexa Fluor 488-labeled antidigoxigenin antibody was used for detection. Although functional gene expression was not detected in this study, detection of cells in a biofilm based on their function was demonstrated.

Biofilms↗

PubMed2001

Long-term changes in off-lesion endocochlear potential after induction of localized lesions in the lateral wall.

Localized lesions were produced in various turns of the guinea pig cochlea by means of a photochemical reaction between systemically administered rose bengal dye and green light illumination. The endocochlear potential (EP) was measured at various off-lesion sites, and a morphological examination was performed. In a previous study, this same investigation was done at 3 days, at which time all sites apical to the lesion showed significant EP depression, and damage to the stria vascularis at the lesion was ongoing. In the present 2-week study, the apical EP values were not different from the basal values, and all experimental values were essentially the same as the EP values found in control animals. Morphological examination revealed that the previously damaged structures were greatly repaired. Localized damage and early apical EP depression followed by damage repair and eventual EP recovery could account for the clinical course of certain cases of idiopathic sudden hearing loss involving low-tone deafness.

Animals↗

PubMed2001

Contributions of three glycosyltransferases to sucrose-dependent adherence of Streptococcus mutans.

Streptococcus mutans produces 3 types of glucosyltransferase (GTF), whose cooperative action is considered to be essential for its cellular adherence to the tooth surface. However, the precise mechanisms for synthesizing adhesive glucans and the specific roles of each GTF in cellular adherence to smooth surfaces have not been elucidated. In the present study, seven types of isogenic mutants of S. mutans MT8148 lacking GTFB, GTFC, and/or GTFD activities were constructed by inactivation of the genes encoding GTFB, GTFC, and/or GTFD. Furthermore, recombinant GTFB, GTFC, and GTFD were prepared from Escherichia coli cells harboring recombinant plasmids containing each of the gtf genes. Using these GTF-deficient mutants and rGTFs, we reconstituted sucrose-dependent adherence of S. mutans resting cells and examined the role of each GTF in vitro. The highest level of sucrose-dependent adherence was found at the ratio of 20 rGTFB:1 rGTFC:4 rGTFD in both the resting cells of GTF-deficient mutants and insoluble glucan synthesized by rGTFs. Moreover, when rGTFC and rGTFD were both present at concentrations of 1.5 mU and 6 mU, respectively, the insoluble glucan synthesized from sucrose by the rGTFs showed a high level of adhesiveness to smooth surfaces, even without rGTFB. These results suggest that the presence of all three GTFs at the optimum ratio is necessary for sucrose-dependent adherence of S. mutans, and that GTFC and GTFD may play significant roles in the synthesis of adhesive and insoluble glucan from sucrose.

Bacterial Adhesion↗