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H Shiga

Publications and source records attributed to H Shiga.

At least 19 recordsLinked to original sources
PubMed2002

GAP junctional channel inhibition alters actin organization and calcium propagation in rat cultured astrocytes.

Astrocytes are connected by gap junctions, which provide intercellular pathways that allow a direct exchange of ions and small metabolites including second messengers and the propagation of electric currents. The roles of gap junctional communication on whole-cell morphology, cytoskeletal organization, and intercellular communication in astrocytes are not yet clear even in vitro, though there are many studies that have examined the active relation between gap junctions and actin filaments in astrocytes. Here we examined the effects of gap junction inhibitors, which do not interrupt the formation but rather the function of gap junctions, on whole-cell morphology, cytoskeletal organization, and intercellular communication in rat cultured astrocytes. Functional blockade of gap junctions during the formation of an astrocytic monolayer resulted in discordance of actin stress fibers between neighboring cells, even though whole-cell morphology of these cells did not change by such treatment. Mechanical stimulation-induced calcium wave propagation was significantly reduced in these actin-discordance cells even after thorough wash out. Differentiation of astrocytes in the presence of gap junction inhibitors was associated with morphological disarrangement among neighboring cells due to disordered alignment of actin stress fibers between cells.Our results indicate that gap junctional communication enables cell-to-cell coordination of actin stress fibers in astrocytes, thus enhancing intercellular communication through calcium spread.

Actins↗
PubMed2001

Kinetic analysis of the bactericidal action of heated scallop-shell powder.

Shell powder of scallop (Patinopecten yessoensis) was exposed to heat treatment at between 200 and 1000 degrees C, and the bactericidal action of the powder slurry was investigated. Shell powder heated at 700 degrees C or higher exhibited bactericidal action against Escherichia coli, Salmonella typhimurium, Staphylococcus aureus and Bacillus subtilis (vegetative cells). The death of bacteria in the shell powder slurry followed first-order reaction kinetics, and the apparent death rate constant (k) was determined. An increase in exposure temperature enhanced the bactericidal action. The bactericidal action is due to calcium oxide that is converted from calcium carbonate, which is the main component of the shell powder, by heat treatment. The slurry temperature is found to significantly affect the bactericidal action of the shell powder. The slope of the Arrhenius plot of k for E. coli and S. aureus that were grown at 37 degrees C exhibited a discontinuous point at approximately 22 degrees C, at which the values of activation energy for the death of bacteria in the powder slurry changed. This temperature corresponds to that of the phase transition of cell membrane lipids. The bactericidal action of the shell powder is greater than that of a NaOH solution of identical pH. Although the pH of the shell powder slurry is high, the slurry was considered to possess other antibacterial mechanisms in addition to that of alkalinity.

Bacteria↗
PubMed2001

Ca2+ signaling regulated by an ATP-dependent autocrine mechanism in astrocytes.

Although the mechanisms of Ca2+ wave propagation in astrocytes induced by mechanical stimulation have been well studied, it is still not known how the [Ca2+]i increases in the stimulated cells. Here, we have analyzed the mechanisms of [Ca2+]i increase in single, isolated astrocytes. Our results showed that there was an autocrine mechanism of Ca2+ regulation mediated by ATP in mechanically stimulated astrocytes. This autocrine mechanism induced the activation of phospholipase C via a G-protein, resulting in Ca2+ release from intracellular Ca2+ stores. A second pathway mediating a [Ca2+]i increase was via a Ca2+ influx from the extracellular space, which, interestingly, suppressed an intracellular Ca2+ oscillation. These two different Ca2+ cascades are involved in signal transduction and may function separately during intercellular communication.

Adenosine Triphosphate↗
PubMed2001

The effect of bolus size on the chewing cycle in humans.

No general agreement exists regarding the effect that bolus size has on masticatory movement, probably because both the size and texture of food change during mastication. In this experiment, in order to clarify the effect of bolus size on masticatory movement, a food that does not change in size and texture--chewing gum--was chosen, and the relationship between bolus size and the chewing cycle was analyzed. Ten healthy subjects in their twenties were asked to chew pieces of softened chewing gum of four different sizes. For ten cycles, beginning with the fifth cycle of mastication, gape and masticatory width were calculated for the spatial parameter of the chewing cycle, and cycle time was calculated as the temporal parameter. The relationship between these parameters and the bolus size was investigated. As the bolus size increased, the spatial and temporal parameters increased. In addition, there was a positive correlation between the bolus size and each parameter. The influence of the bolus size was as follows: gape, r = 0.91; masticatory width, r = 0.79; and cycle time, r = 0.74 (all, P < 0.001). From these results it was concluded that the shape of the chewing cycle was altered by the size of the food bolus, and that the changes in sensory input from the peripheries greatly affected the masticatory movement.

Journal Article↗
PubMed2001

Current topics on cytokine removal technologies.

It has been widely accepted that cytokines play important roles in the development of organ failure in various pathophysiological conditions of critically ill patients. Various new technologies, including continuous renal replacement therapy, have been developed for the removal of causative humoral mediators in sepsis or other critical conditions. Nonselective blood purification technologies, such as hemofiltration and plasma exchange, are applied in cytokine removal technology. However, the more selective blood purification technologies, such as adsorption, and the combination of those technologies, should be considered in future applications. Only through a prospective randomized controlled study can it be elucidated whether or not these technologies have efficacy in the treatment of sepsis and critically ill patients with hypercytokinemia. We should join and discuss the design of future clinical trials with a standardized strategy for the evaluation of the technologies.

Adsorption↗
PubMed2001

Usefulness of plasma exchange plus continuous hemodiafiltration to reduce adverse effects associated with plasma exchange in patients with acute liver failure.

OBJECTIVE: To efficiently remove middle-molecular-weight substances such as hepatic toxins and minimize adverse effects associated with plasma exchange implementation, we have performed plasma exchange slowly in combination with continuous hemodiafiltration. This study was designed to determine the usefulness of plasma exchange with continuous hemodiafiltration in reducing the adverse effects associated with implementation of plasma exchange alone. DESIGN: A retrospective clinical study. SETTING: University teaching hospital. PATIENTS: The study involved 90 patients with liver failure who had been treated with plasma exchange in our department over the past 12 yrs. We examined these patients by dividing them into two groups (48 patients treated with plasma exchange alone and 42 patients treated with plasma exchange plus continuous hemodiafiltration at the time of plasma exchange implementation). MEASUREMENTS AND MAIN RESULTS: Baseline blood Na+ concentration, HCO3- concentration, and colloid osmotic pressure were followed after implementation of plasma exchange to compare the frequency of development of three adverse effects (hypernatremia, metabolic alkalosis, and sharp decrease in colloid osmotic pressure) in the two groups. Hypernatremia was found in 26.7% of treatments in the group with plasma exchange alone and 3.3% in the group of plasma exchange plus continuous hemodiafiltration, and metabolic alkalosis was found in 30.6% of treatments in the group with plasma exchange alone and 4.9% in the group of plasma exchange plus continuous hemodiafiltration; both percentages were significantly higher in the group with plasma exchange alone (p <.001). A sharp decrease in colloid osmotic pressure occurred in 13.3% of treatments in the group with plasma exchange alone but was not observed at all in the patients treated with plasma exchange plus continuous hemodiafiltration. CONCLUSIONS: We conclude that adverse effects associated with plasma exchange for artificial liver support for liver failure can be alleviated with use of plasma exchange plus continuous hemodiafiltration instead of plasma exchange alone.

Adolescent↗
PubMed2001

Heated scallop-shell powder slurry treatment of shredded cabbage.

The main component of scallop-shell powder is calcium carbonate (CaCO3). Through heat treatment, CaCO3 in the shell is converted to CaO, which exhibits antibacterial activity. The disinfecting effect of heated scallop-shell powder on shredded cabbage was investigated for various powder concentrations (0.1 to 1.0 g dm(-3)) and treatment temperatures (10 to 40 degrees C). Scallop-shell powder treatment was found to reduce the aerobic bacteria count in cabbage, with increasing effectiveness at higher powder concentrations and treatment temperatures. Coliforms were completely eliminated within 5 min with as little as 0.1 g dm(-3) powder treatment. During storage at 4 degrees C, aerobic bacterial counts did not increase after powder treatment, whereas counts increased with water-washing or sodium hypochlorite treatment at 200 microg dm(-3). The inactivation pattern of bacterial cells in shredded cabbage involved an accelerated decline followed by an extended tail at powder concentrations of 0.1 and 0.5 g dm(-3). We postulate that a fraction of bacterial cells in the initial population becomes tolerant to the shell powder. A proposed model accurately predicts the reducing bacterial counts on shredded cabbage by scallop-shell powder treatment. The decrease in the L-ascorbic acid content of shredded cabbage was approximately 20 to 30% for scallop-shell powder treatment at 0.1 and 0.5 g dm(-3) (20 degrees C), which is almost identical to that by sodium hypochlorite treatment at 200 micorg dm(-3).

Bacteria, Aerobic↗
PubMed2000

Prognostic value of c-erbB2 and other markers in patients treated with chemotherapy for recurrent head and neck cancer.

BACKGROUND: Chemotherapy is widely used in patients with recurrent head and neck cancer, but no clear markers are available that can predict response to treatment or survival in these patients. METHODS: Twenty-nine patients evaluated in this study had recurrent head and neck squamous carcinomas, previously treated with surgery and/or radiotherapy. Patients received either cisplatin and 5-fluorouracil (5-FU) (n = 15) or cisplatin and paclitaxel (Taxol) (n = 14). Expression of c-erbB2, p53, glutathione S-transferase pi, multidrug resistance-associated protein, thymidylate synthase, and glutathione synthetase were evaluated in biopsy tissues. RESULTS: Response to chemotherapy was significantly correlated with improved survival (progression-free survival, p =.0005; overall survival, p =. 007). Of the factors examined, expression of c-erbB2 was associated with significantly decreased progression-free survival (p =.023) and overall survival (p =.029). This was seen in patients treated with cisplatin/taxol but not in patients treated with cisplatin/5-FU. CONCLUSION: Expression of c-erbB2 may be a clinically useful predictor of survival in this group of patients.

Adult↗
PubMed2000

Comparison of Sepsis-related Organ Failure Assessment (SOFA) score and CIS (cellular injury score) for scoring of severity for patients with multiple organ dysfunction syndrome (MODS).

OBJECTIVE: To evaluate the usefulness of cellular injury score (CIS) and Sepsis-related Organ Failure Assessment (SOFA) score for determination of the severity of multiple organ dysfunction syndrome (MODS). DESIGN: A prospective observational study. SETTING: A medical and surgical intensive care unit (ICU) of a teaching hospital. PATIENTS: Forty-seven consecutive MODS patients. MEASUREMENTS AND RESULTS: SOFA score and CIS were measured every day for 12 months for 47 MODS patients. Comparison was made of the SOFA score and CIS for usefulness in the scoring of severity of MODS in 26 survivors and 21 non-survivors. In addition, receiver operating characteristics (ROC) analysis was used to determine the usefulness of these two indexes as predictors of prognosis. No significant differences were found on admission between the survivors and non-survivors, but significant differences between the two subgroups (p < 0.001) were found in maximum value within 1 week after admission and maximum value during the course of treatment for both indexes. Analysis of changes after admission indicated that significant differences between survivors and non-survivors began to appear on day 3 of admission for both indexes; at that time SOFA score began to deteriorate in the non-survivors while CIS began to improve in the survivors. ROC analysis demonstrated that the area under the ROC curve was 0.769 for SOFA scores and 0.760 for CIS. CONCLUSIONS: Both SOFA score and CIS sequentially reflected the severity of MODS. Furthermore, they were comparable in diagnostic value as predictors of prognosis. These findings may indicate the possibility that MODS is a summation of effects of cellular injury. In addition, sequential evaluation of both SOFA score and CIS would provide a more accurate prediction of prognosis than conventional methods.

Aged↗
PubMed2000

Quantitative analyses of topography and elasticity of living and fixed astrocytes.

The topography and elasticity of living and fixed astrocytes cultured from the rat cerebra were studied quantitatively by atomic force microscopy (AFM). Ridge-like structures reflecting F-actin beneath the cell membrane were prominent in the contact-mode images of living astrocytes. Many of these ridges became unclear after fixation (2% glutaraldehyde). In addition, the ridge-like structures were invisible in the topography of living cells observed at zero-loading force in the force mapping mode, which is considered to show the real cell surface not pressed down by an AFM tip. The topography of fixed cells observed both in the contact mode and at zero-loading force in the force mapping mode was similar to that of living cells observed at zero-loading force in the force mapping mode, although some deformed areas were detected in the fixed cells. The elasticity map images of living astrocytes showed that the cell membrane above the nucleus was softer (2-3 kPa) than the surroundings, and that the cell membrane above F-actin was stiffer (10-20 kPa) than the surroundings. In the elasticity map images of fixed astrocytes, on the other hand, the elasticity of the cells was found to be relatively uniform (200-700 kPa) irrespective of the inner structures of cells. These results show that images observed by AFM should be carefully examined in consideration of the force introduced to specimens and the elasticity of specimens to find out the real surface topography.

Actins↗
PubMed1999

Ankle arthrodesis in rheumatoid arthritis using an intramedullary nail with fins.

We describe an intramedullary nail with fin-like longitudinal ridges that we have developed for arthrodesis of the ankle in rheumatoid arthritis. Four fins with sharp tips were attached to the distal part of a cylindrical nail to stabilize the tibiotalar and subtalar joints. We used this nail in 15 feet of 15 patients with rheumatoid arthritis who were followed for an average of 34.9 months. Postsurgery, 13 patients were allowed to bear weight immediately, as tolerated, without immobilization. By 3 weeks, these patients were able to bear weight fully. Solid fusion of the ankle joint in an acceptable position and good clinical results were obtained in all patients. The only complications were two cases of delayed wound-healing.

Adult↗
PubMed1999

Dynamics of astrocyte adhesion as analyzed by a combination of atomic force microscopy and immuno-cytochemistry: the involvement of actin filaments and connexin 43 in the early stage of adhesion.

We observed the time-dependent morphological alteration of astrocytes during their adhesion by atomic force microscopy (AFM) and investigated the relationships between this morphological alteration and the localization of actin filaments and connexin 43 by immunocytochemistry. The fine processes observed as fine ridge-like structures by AFM were closely concerned with actin filaments by immunocytochemistry. During the adhesion of astrocytes, actin filaments appeared to be aligned regularly beyond the borders among different cells. Detectable connexin immunoreactivity was changed in the following regions: 1) the tips of fine cell processes and the cell margin when astrocytes started to adhere; 2) the border of cells when astrocytes tightly adhered; and 3) non-specific sites when astrocytes became a cluster. In the former two cases, the immunopositive spots for connexin were observed to colocalize with the tips of cell processes with actin filaments. These results strongly suggest that connexin associated with actin filaments at the tip of cell processes plays an important role in the early stage of the adhesion of astrocytes. These observations afford valuable clues for understanding the glial communication.

Actin Cytoskeleton↗
PubMed1999

[Glutathione and cisplatin resistance in head and neck cancer].

UNLABELLED: Since glutathione is considered to be an important mediator of cancer cell resistance to cisplatin-based chemotherapy, we investigated glutathione in head and neck cancer by both laboratory and clinical investigations. MATERIALS AND METHODS: Intracellular glutathione concentration was measured in 7 different cell lines that originated from head and neck cancer and was correlated to their IC50 to cisplatin. Expression of gamma-glutamyl cysteine (gamma-GCS) mRNA was assessed by in situ hybridization and gamma-glutamyl transpeptidase (GGT) expression was assessed with immnunohistochemistry of 56 biopsy specimens from 51 clinical cases. Both these enzymes are important for maintenance of intracellular glutathione concentration. RESULTS: Intracellular glutathione concentration was strongly correlated with cisplatin IC50 (R2 = 0.814, P = 0.0012), suggesting that glutathione plays a major role in cisplatin resistance in head and neck cancer. High gamma-GCS expression was observed in 27 out of 47 specimens (57%), but the response rate to chemotherapy (63%) in the high expression group was not significantly different to the low expression group (P = 0.20). High GGT expression was observed in 32 out of 53 specimens (60%), but the response rate in the high GGT group was not significantly different to that of the GGT group. CONCLUSION: Although intracellular glutathione plays an important role in resistance to cisplatin in head and cancer cell lines, we failed to prove that two enzymes that contribute to the maintenance of intracellular glutathione concentration are predictive factors for the response to cisplatin-based chemotherapy. Since clinical cases are further complicated by interactions of the immune system, involvement of a variety of genes related to oncogenesis, and accompanying drugs such as 5FU, it is very difficult to determine a single factor to predict the response to cisplatin. More precise analysis is necessary to determine how head and neck cancer resists cisplatin.

Carcinoma, Squamous Cell↗
PubMed1999

Longterm outcome of total joint arthroplasty in nonambulatory patients with rheumatoid arthritis.

OBJECTIVE: To assess the outcome of minimum 10 year followup of total joint arthroplasty (TJA) in nonambulatory patients with rheumatoid arthritis (RA). METHODS: TJA was performed in 40 nonambulatory patients with RA who satisfied the following criteria: (1) strong motivation; (2) good relationship with our medical staff; (3) no marked cervical cord lesion: (4) absence of severe systemic complications. These included 38 women and 2 men whose average age at the initiation of TJA was 58.8 years. The duration of time between loss of walking ability and surgery was 2 months to 5 years. Average hospitalization time was 4.5 months. Followup after the last surgery was 10 to 18 years. RESULTS: One year after the last surgery, 28 of the 40 patients could walk outdoors again, 11 indoors, and one was still unable to walk. By 5 years after surgery, 9 patients had died of diseases unrelated to surgery. Of the remaining 31 patients, 19 could walk outdoors, 10 indoors, and 2 could not walk. Deterioration of walking was observed in 13 patients (41.9%) compared with one year after surgery. By 10 years after surgery, 32 patients had died of diseases unrelated to surgery, 4 could walk outdoors, 4 indoors. Of these, 4 patients (50%) had worsened in walking ability compared with one or 5 years after surgery. Major complications of TJA were observed in 12 patients. These were femoral neck fractures in 3, supracondylar femoral fractures in 3, loosening of the acetabulum socket in 4, loosening of the femoral hip prosthesis in 2. CONCLUSION: TJA should be a useful treatment for restoration of walking in nonambulatory patients with RA. However, even after TJA, walking ability deteriorated in about half of the patients as the duration of followup observations exceeded 5 years.

Adult↗
PubMed1999

Prognostic value of p53, glutathione S-transferase pi, and thymidylate synthase for neoadjuvant cisplatin-based chemotherapy in head and neck cancer.

Neoadjuvant cisplatin-based chemotherapy has been widely used in the last decade for organ preservation or unresectable disease in advanced stage head and neck cancer. We examined the expression of a series of tumor markers that have been associated with chemotherapy resistance in pretreatment biopsies from 68 patients who received cisplatin-based neoadjuvant chemotherapy at either of two institutions. Patients received either cisplatin/5-fluorouracil (n = 49) or cisplatin/paclitaxel (n = 19). Expression of p53, glutathione S-transferase pi (GSTpi), thymidylate synthase (TS), c-erbB2, and multidrug resistance-associated protein was examined by immunohistochemistry. Expression of glutathione synthetase mRNA was measured by in situ hybridization. The overall response rate for cisplatin-based neoadjuvant treatment was 79%. The expression of several of the tumor markers was associated with resistance to neoadjuvant treatment, but none reached statistical significance. Overall survival (OS) was strongly correlated with the absence of p53 expression. The OS at 3 years was 81% in the p53-negative group, whereas it was 30% in the p53-positive group for patients treated with neoadjuvant chemotherapy (P < 0.0001). Expression of GST pi and TS was also significantly correlated with decreased OS after neoadjuvant treatment. At 3 years, the OS rate was 82% in the low GSTpi score group, compared to 46% in the high GSTpi score group (P = 0.0018). In the TS-negative group, the 3-year OS rate was 71% compared with 40% in the TS-positive group (P = 0.0071). We conclude that p53, GSTpi, and TS may be clinically important predictors of survival in patients receiving neoadjuvant chemotherapy for head and neck cancer.

Adolescent↗
PubMed1998

Long-term results of Yoshino total knee arthroplasties in rheumatoid arthritis.

A review was made of 267 Yoshino total knee arthroplasties performed on 184 patients with rheumatoid arthritis between June 1978 and December 1983. The average duration of follow-up was 14.3 years. Of these patients 46.7% died during the follow-up period. The main causes of death were cardiac disease, respiratory disease and renal disease. According to the Japanese Orthopaedic Association (JOA) knee rating system, JOA scores decreased significantly with time after surgery, but remained significantly higher than the preoperative scores. The flexion angle after surgery had decreased compared with the preoperative flexion angle and decreased further 3 years after surgery and later. The cumulative survival rate was 88.6%. This rate was mainly affected by postoperative infection and aseptic loosening of the tibial components.

Adult↗