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Biomedical subjects

S Yamada

Publications and source records attributed to S Yamada.

At least 73 records · Page 4Linked to original sources

Sublabial transsphenoidal pituitary surgery: a new modified technique for a less-invasive sublabial approach.

The history of the transsphenoidal approach for pituitary surgery is reviewed in this mini review. There are several approaches to the sphenoid sinus, and the sublabial transseptal and transnasal transseptal approaches are presently the most widely accepted standard techniques. Although the transnasal approach has several advantages in comparison with the sublabial approach, it is difficult to accomplish in the small nostril without an alotomy incision or external rhinoplasty incision, which may lead to noticeable scarring or nasal deformity. Therefore, the sublabial approach still remains the workhorse method, especially for patients with small nostrils like Asian people including the Japanese. We have developed a less-invasive sublabial approach to overcome the disadvantages associated with the conventional sublabial approach. The basic differences between this modified sublabial approach and the conventional approach are: a smaller incision (1-1.5 cm long) and almost midline vertical skin incision underneath the upper lip, minimal development of an inferior tunnel, no widening of the maxillary rim of the piriform aperture, and a strictly unilateral approach. This less-invasive approach uses a slim and small nasal speculum originally designed for the transnasal approach. This modified sublabial approach was applied to 41 patients and was confirmed to be a simple, rapid, and less-invasive technique with significantly fewer mucosal complications compared with the conventional approach. We conclude that this modified sublabial approach offers a good alternative to the conventional standard sublabial approach.

Humans↗

Compositional analysis of root cementum and dentin after Er:YAG laser irradiation compared with CO2 lased and intact roots using Fourier transformed infrared spectroscopy.

The present study examines the dental root after Er:YAG laser irradiation, compared with CO2 lased and non-treated surfaces, using Fourier Transformed Infrared (FTIR) spectroscopy. Freshly extracted human teeth were irradiated by Er:YAG laser at an energy output of 40 mJ/pulse, 10 Hz (0.4 watts), with or without water coolant, and by CO2 laser at an energy output of 0.5 watts in continuous wave mode without coolant. The surfaces were chalky and smooth after irradiation by Er:YAG laser with water coolant, were charred and irregular after irradiation by Er:YAG laser without water coolant, and were completely carbonized after CO2 laser irradiation. The FTIR profiles from samples of the surfaces that were irradiated by Er:YAG laser with water coolant were similar to those from non-treated samples, except for a slight decrease on the OH and amide bands, which are mainly related to organic components. This decrease was observed to be extreme after CO2 laser irradiation and moderate after Er:YAG laser irradiation without coolant. The formation of new bands showing toxic substances was observed to a large extent after CO2 laser irradiation and to a smaller extent after Er:YAG laser irradiation without water coolant. In contrast, no such bands were detected after Er:YAG laser irradiation with water coolant. The present results show that these laser treatments selectively ablated more organic components than inorganic components and that Er:YAG laser irradiation with water coolant did not cause major compositional changes or chemically deleterious changes in either root cementum or dentin.

Aluminum Silicates↗

Effect of treatment with nifedipine, an L-type calcium channel blocker, on muscular atrophy induced by hindlimb immobilization.

The purpose of this study was to investigate whether the prevention of calcium influx through L-type calcium channels contributed to the attenuation of muscular atrophy induced by hindlimb immobilization (HI) in a shortened position. Mice were divided into four groups (8 mice/group): control; nifedipine; HI; and HI with nifedipine. Mice received nifedipine at a dose of 5 mg/kg one day before and during the 8 days of HI. Quantitative alterations in the amount of myosin heavy chain (MyHC) and actin proteins in the soleus muscle were analyzed using SDS-PAGE. The weight of the soleus muscle decreased significantly by 40.8% (P<0.05) and 27.0% (P<0.05) after the hindlimb immobilization in the HI and HI with nifedipine groups, respectively, when compared to that of the control or nifedipine groups. Treatment with nifedipine alone appeared to have no effect on muscle mass or the amount of myofibrillar proteins. The level of MyHC proteins decreased significantly by 25.1% (P<0.001) and 17.4% (P<0.001) in the HI and HI with nifedipine groups, respectively. The level of MyHC protein in the HI with nifedipine group was significantly greater than that of the HI group (P<0.05), although there were no significant differences in the amount of actin protein. These findings suggest that nifedipine treatment may have a beneficial effect on muscular atrophy.

Actins↗

Involvement of CD27/CD70 interactions in antigen-specific cytotoxic T-lymphocyte (CTL) activity by perforin-mediated cytotoxicity.

CD27 molecules are shown to be essential in the regulation of the death, activation and differentiation of T and B cells. However, the influence of CD27 on cytotoxic T-cell function remains obscure. Autologous EBV transformed B-cell lines (LCL), which highly express CD27 ligand CD70, here stimulated T cells and induced the cytotoxic T-lymphocyte (CTL) activity via T-cell antigen receptors (TCR). The cytotoxicity against LCL was diminished when anti-CD70 blocking MoAb was added initially in the culture. Resting T cells killed more CD70-transfected P815 cells than wild type P815 cells in the presence of anti-CD3 MoAb as measured by a 4-h 51Cr release assay, and the cytotoxicity of both of the cell populations completely disappeared in the presence of concanamycin A (CMA). The expression of the perforin by the LCL-induced CTL in the presence of anti-CD70 blocking MoAb was diminished as compared with that without the blockage of CD27/CD70 interactions. The CTL induced by LCL did not kill Fas-transfected WR cells. CD27 signalling in the T cells did not affect Fas ligand (FasL) mRNA expression, LAK activity and IFN-gamma synthesis in humans. Our data demonstrate that CD27/CD70 interactions enhance the cytotoxicity of CTL in the induction phase through enhancement of killing activity induced via the perforin-dependent mechanism, but not via the Fas/FasL system.

Antigens, CD↗

Diminution of early insulin response to glucose in subjects with normal but minimally elevated fasting plasma glucose. Evidence for early beta-cell dysfunction.

AIM: Systematic analysis of beta-cell function in Japanese health examinees. METHODS: In 938 Japanese health examinees (627 men and 311 women, mean age and body mass index, 54.0 years and 23.6 kg/m2, respectively), plasma specific insulin was measured at fasting and during a 75-g oral glucose tolerance test. The subjects were stratified into six groups based on fasting plasma glucose < or = 5.1 mmol/l, 5.2-6.0 mmol/l, 6.1-6.9 mmol/l, 7.0-7.8 mmol/l, 7.9-8.7 mmol/l, and > or = 8.8 mmol/l as the 1st, 2nd, 3rd, 4th, 5th and 6th groups, respectively. RESULTS: Distribution of fasting insulin showed a very modest 'inverted U' shape, with the peak in the 5th group. Progressive increase from the 1st toward the 5th group was significant. In contrast, the ratio of change in insulin to change in glucose from 0 to 30 min during the glucose tolerance test was greatest in the 1st group and progressively declined in the groups with higher fasting glycaemia. Difference in the ratio was most striking and highly significant between the 1st and 2nd groups. Distribution of the insulin to glucose ratio of subjects with normal glucose tolerance significantly overlapped with that of untreated patients with diabetes. CONCLUSIONS: In a Japanese population, (i) beta-cell starts to deteriorate during normoglycaemia with a minimal elevation of fasting plasma glucose, and (ii) there are glucose-tolerant subjects with beta-cell dysfunction.

Adolescent↗

Roles of DNA-dependent protein kinase and ATM in cell-cycle-dependent radiation sensitivity in human cells.

PURPOSE: The roles of DNA-dependent protein kinase (DNA-PK) and ATM in the cell-cycle-dependent radiosensitivity in human cells were investigated. METHODS AND MATERIALS: A DNA-PK activity-deficient human glioblastoma cell line M059J, ataxia telangiectasia cell lines AT3BISV and AT5BIVA, and control cell lines were used. Wortmannin inhibited DNA-PK and ATM activities. Cells were synchronized by hydroxyurea. Progression through the cell cycle was analysed by flow cytometry. RESULTS: M059J exhibited hyper-radiosensitivity throughout the cell cycle, with extreme hyper-radiosensitivity in G to early S-phase compared with the control cell line M059K. AT3BISV and AT5BIVA exhibited hyper-radiosensitivity throughout the cell cycle but showed a similar pattern of cell-cycle-dependent radiosensitivity to that observed in LM217 or HeLa cells. In AT3BISV and AT5BIVA, radiosensitization by wortmannin was observed throughout the cell cycle and was most prominent in G1 to early S-phase. Wortmannin did not sensitize M059J to ionizing radiation in any cell-cycle phase. DNA-PK activities were not different throughout the cell cycle. CONCLUSION: The results suggest that (1) non-homologous endjoining plays a dominant role in G1 to early S-phase and a minor role in late S to G2-phase in repairing DNA double-strand breaks, (2) the role of ATM in repairing double-strand breaks may be almost cell-cycle-independent and (3) the dominant role of non-homologous end-joining during G1 to early S-phase is not due to cell-cycle-dependent fluctuations in DNA-PK activity.

Androstadienes↗

Similarity between eruptions induced by sulfhydryl drugs and acute cutaneous graft-versus-host disease after bone marrow transplantation.

Cutaneous GVHD is histologically similar to eruptions induced by drugs containing a sulfhydryl group. The levels of interleukin-2 and interleukin-2 receptor were determined in a group of patients undergoing bone marrow transplantation (BMT) without graft-versus-host disease or any other complications and in a group with cutaneous graft-versus-host disease (GVHD) alone. In patients who only developed cutaneous GVHD, both interleukin-2 and inter-leukin-2 receptor levels were elevated when the disease was evident. As the elevation of these parameters became more marked, the grade of cutaneous graft versus-host disease also increased. In some patients, only one of the two parameters was elevated and the grade of graft-versus-host disease was low or no skin manifestations were seen. These findings suggest that interleukin-2 and interleukin-2 receptor act together in the development of cutaneous GVHD. This study also showed that the mechanism of cutaneous GVHD resembles that involved in the induction of eruptions by sulfhydryl-containing drugs.

Acute Disease↗

Diurnal variation in the response of the mandible to orthopedic force.

Bone and cartilage metabolism is known to be more active during rest than during periods of activity. The purpose of this study was to examine the hypothesis that mandibular retractive force could be more effective when applied to rats during rest. Mandibular retractive force caused a considerable reduction in the condylar length in experimental groups, and the magnitude of this reduction was greater in the Light-period (08:00-20:00) group than in the Dark-period (20:00-08:00) group. The differentiation and proliferation of chondrocytes were inhibited in animals in the Light-period group, compared with those in the Dark-period group. These results suggest that the orthopedic effects of mandibular retractive force vary depending on the time of day the force is applied, and that such force may be more effective while animals are resting than while they are active.

Analysis of Variance↗

Selective and sustained occupancy of prostatic alpha1-adrenoceptors by oral administration of KMD-3213 and its plasma concentration in rats.

This study examined the ex-vivo occupancy by KMD-3213 of alpha1-adrenoceptors in the prostate and other tissues of rats in terms of tissue selectivity and duration of occupancy in relation to plasma concentration. Oral administration of KMD-3213 (0.2-20.2 micromol kg(-1), 0.5 h) dose-dependently decreased [3H]prazosin binding sites (Bmax) in the prostate (42-74%) and submaxillary gland (54-88%) compared with the control value. In contrast, there was only a slight change in the Bmax values in the spleen and cerebral cortex of KMD-3213-treated rats. The alpha1-adrenoceptor occupancy in the prostate and submaxillary gland was increased, with plasma free concentration of KMD-3213 at 0.5 h after oral administration of KMD-3213 (0.6-20.2 micromol kg(-1)). The receptor occupancy in these tissues was much greater than that in the spleen, heart or cerebral cortex. After oral administration of KMD-3213 (6.1 micromol kg(-1)), the alpha1-adrenoceptor occupancy in the prostate and submaxillary gland occurred rapidly, in parallel with the rise in the plasma concentration of the drug, and it lasted for at least 24 h, despite a remarkable decrease in the plasma concentration. It is concluded that KMD-3213 may produce fairly selective and sustained occupancy of alpha1-adrenoceptors in the prostate, a target organ for treatment of bladder outlet obstruction in patients with benign prostatic hyperplasia.

Administration, Oral↗

Time-dependent potentiation of the beta-cell is a Ca2+-independent phenomenon.

When isolated rat pancreatic islets are treated with 16.7 mM glucose, a time-dependent potentiation (TDP) of insulin release occurs that can be detected by subsequent treatment with 50 mM KCl. It has been thought that TDP by glucose is a Ca2+-dependent phenomenon and only occurs when exposure to glucose is carried out in the presence of Ca2+. In contrast to this, we now demonstrate TDP under stringent Ca2+-free conditions (Ca2+-free buffer containing 1 mM EGTA). In fact, under these Ca2+-free conditions glucose caused an even stronger TDP than in the presence of Ca2+. TDP induced by glucose in the absence of extracellular Ca2+ was unaffected by inhibitors of protein kinase C (PKC). However, cerulenin or tunicamycin, two inhibitors of protein acylation, eradicated TDP without affecting glucose metabolism. The TDP by glucose was not associated with an increase in the cytosolic free Ca2+ concentration ([Ca2+]i) during subsequent treatment with high K+. Exposure of islets to forskolin under Ca(2+)-free conditions did not cause TDP despite a large increase in the cellular cAMP levels. In conclusion, glucose alone induces TDP under stringent Ca2+-free conditions when [Ca2+]i was significantly lowered. Protein acylation is implicated in the underlying mechanism of TDP.

Acylation↗

Expression of alkaline phosphatase induces rapid and artificial mineralization in specific transformed Escherichia coli.

Matrix vesicles (MV) having high alkaline phosphatase (ALP) activity act as initiators of biological mineralization. Although bacteria have similar membranous structures to MV, ALP mediated mineralization has not been studied in bacterial cells. Escherichia coli was transformed with a bacterial ALP gene in this study. Recombinant E. coli overproducing ALP induced mineralization through hydrolysis of calcium-glycerophosphate (Ca-GP). Fourier transform infrared spectroscopy and electron microscopy combined with electron diffraction revealed newly formed hydroxyapatite mineral deposits. These findings suggest that hydrolysis of Ca-GP through ALP induced high Ca and Pi concentrations within bacterial cells followed by complete bacterial mineralization.

Alkaline Phosphatase↗

[Lobectomy under video-assisted thoracoscopic surgery for pulmonary aspergillosis].

A 70-year-old man was admitted to our hospital because of hemoptysis and abnormal shadows on chest film. He was given a diagnosis of pulmonary aspergilloma with fungus ball by computed tomography and other evaluations. Success rate of systemic or topical treatment with antifungal agents is reported to be 80%. At this case lobectomy under VATS was chosen because he had chronic liver dysfunction by hepatitis type C and the lesion was localized in the right upper lobe. Bronchial artery embolization was performed prior to the operation in order to minimise bleeding on lysing the adhesion between the chest wall and the lobe with aspergilloma. Operation was underwent safety with a bloodloss of 170 ml. Success rate of operation is reported to be 95.8% in pulmonary resection. If bronchial artery embolization is successful and the lesion is localized, lobectomy under VATS can be good option in selected patients.

Aged↗

Oral eicosapentaenoic acid for acute colonic graft-versus-host disease after bone marrow transplantation.

We investigated whether pretreatment with eicosapentaenoic acid, an inhibitor of leukotriene (LT) B4, could ameliorate acute colonic graft-versus-host disease (GVHD) after bone marrow transplantation (BMT). Seventeen patients undergoing unrelated BMT were divided into two groups, with eight patients receiving eicosapentaenoic acid and nine not receiving it. The grade of GVHD after transplantation was compared with that estimated from the pretransplantation LTB4 level. The levels of LTB4 and several cytokines were also monitored. The actual grade of GVHD was lower than that estimated from LTB4 levels in three of the eight patients from the treated group, and there was a significant difference between the treated and untreated groups (p < 0.05, chi 2 test). The levels of LTB4, tumor necrosis factor-alpha (TNF-alpha), and interferon-gamma (IFN-gamma) were all significantly lower in the treated group (p < 0.05, Student's t-test). These findings suggest that eicosapentaenoic acid may ameliorate acute colonic GVHD when administered from before BMT.

Acute Disease↗

Brain receptor binding characteristics and pharmacokinetic-pharmacodynamic analysis of thyrotropin-releasing hormone analogues.

Thyrotropin-releasing hormone (TRH) receptor binding in the rat brain after intravenous (i.v.) injections of novel TRH analogues, taltirelin and montirelin, was examined and the data were analyzed in relation to their plasma concentrations which were simultaneously determined. Taltirelin and montirelin inhibited specific [3H]-Me-TRH binding in the rat brain and their Ki values were 311 and 35.2 nM, respectively. The i.v. injection of taltirelin and montirelin (0.1-3 mg/kg) produced a significant reduction in [3H]-Me-TRH binding sites (Bmax values) in the rat brain. The reduction by both agents tended to reach a maximum after 60 min and lasted up to at least 120 min. On the other hand, the i.v. injection of both agents had little significant effect on the apparent dissociation constant (Kd) for [3H]-Me-TRH in the rat brain. Plasma concentrations of taltirelin and montirelin in rats peaked immediately after i.v. injection, and thereafter they decreased with t 1/2 of 23.0 and 14.1 min, respectively. Counter-clockwise hysteresis between the plasma concentration and receptor occupancy of these agents was observed after the i.v. injection of taltirelin and montirelin, and the temporal delay between plasma concentration and brain receptor occupancy was successfully minimized using the "effect compartment" model in combination with the "linear-effect" model. We concluded that taltirelin and montirelin exert a fairly potent effect following sustained occupation of brain TRH receptors under in vivo condition. Thus, both agents could be clinically useful for the treatment of CNS disorders.

Animals↗

Calmegin is required for fertilin alpha/beta heterodimerization and sperm fertility.

Loss of the endoplasmic reticulum resident chaperone calmegin leads to the production of sterile sperm that do not bind to the egg zona pellucida (M. Ikawa et al., 1997, Nature 387, 607-611). In the present study, we demonstrate that calmegin -/- sperm were defective in migrating into the oviducts and in binding to the egg plasma membrane. Despite the impaired adhesive function, calmegin -/- sperm could fertilize eggs when zonae pellucidae were partially dissected, and eggs fertilized in this manner could develop normally to term. Since these sperm characteristics were similar to those found in fertilin beta -/- sperm, we investigated the interaction of calmegin with fertilin beta. Using immunoprecipitation techniques, calmegin was found to bind to sperm membrane proteins, fertilin alpha and beta, during spermatogenesis. The binding was specific to calmegin: another endoplasmic reticulum chaperone calnexin, a calmegin homologue, was not able to bind to fertilin alpha and beta. In the calmegin -/- mice, a loss of heterodimerization of fertilin alpha and beta was observed and fertilin beta was not detectable in mature sperm. The data not only explain why the calmegin and fertilin beta knockout mouse lines share a common infertile phenotype, but also reveal the importance of the maturation of sperm membrane proteins in the endoplasmic reticulum.

ADAM Proteins↗

The nonhelical tail domain of keratin 14 promotes filament bundling and enhances the mechanical properties of keratin intermediate filaments in vitro.

Keratin filaments arise from the copolymerization of type I and II sequences, and form a pancytoplasmic network that provides vital mechanical support to epithelial cells. Keratins 5 and 14 are expressed as a pair in basal cells of stratified epithelia, where they occur as bundled arrays of filaments. In vitro, bundles of K5-K14 filaments can be induced in the absence of cross-linkers, and exhibit enhanced resistance to mechanical strain. This property is not exhibited by copolymers of K5 and tailless K14, in which the nonhelical tail domain has been removed, or copolymers of K5 and K19, a type I keratin featuring a short tail domain. The purified K14 tail domain binds keratin filaments in vitro with specificity (kD approximately 2 microM). When transiently expressed in cultured cells, the K14 tail domain associates with endogenous keratin filaments. Utilization of the K14 tail domain as a bait in a yeast two-hybrid screen pulls out type I keratin sequences from a skin cDNA library. These data suggest that the tail domain of K14 contributes to the ability of K5-K14 filaments to self-organize into large bundles showing enhanced mechanical resilience in vitro.

Animals↗

Morphological evidence for lipid peroxidation and protein glycoxidation in spinal cords from sporadic amyotrophic lateral sclerosis patients.

For determining whether both the spinal cord motor neurons and glial cells are exposed to increased oxidative stress in amyotrophic lateral sclerosis (ALS), we performed an immunohistochemical investigation of end products of lipid peroxidation and protein glycoxidation in spinal cords from seven sporadic ALS patients and seven age-matched control individuals. In the ALS spinal cords, immunoreactivities for adducts of 4-hydroxy-2-nonenal-histidine and crotonaldehyde-lysine as markers of lipid peroxidation, N(epsilon)-(carboxymethyl)lysine as a marker of lipid peroxidation or protein glycoxidation, and pentosidine as a marker of protein glycoxidation were localized in the gray matter neuropil and almost all of the motor neurons, reactive astrocytes and microglia/macrophages, whereas none of the immunoreactivities for N(epsilon)-(carboxyethyl)lysine or argpyrimidine as markers of protein glycoxidation or enzymatic glycolysis, or pyrraline or imidazolone as markers of nonoxidative protein glycation were detectable. The control spinal cords displayed no significant immunoreactivities for any of these examined products. Our results indicate that in sporadic ALS, both lipid peroxidation and protein glycoxidation are enhanced in the spinal cord motor neurons and glial cells, and suggest that the formation of certain products in these abnormal reactions is implicated in motor neuron degeneration.

Aged↗