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Biomedical subjects

Y Shimizu

Publications and source records attributed to Y Shimizu.

At least 271 records · Page 15Linked to original sources
PubMed1999

Regulation of integrin function by T cell activation: points of convergence and divergence.

Lymphocyte adhesiveness is dynamically regulated in response to conditions in the extracellular environment. One mechanism of regulation of integrin adhesion receptors involves a rapid, but transient, increase in integrin function upon T lymphocyte activation. These integrin activating signals can be initiated either via ligation of Ig superfamily members that are coupled to tyrosine kinase cascades, such as the CD3/T cell receptor, CD2, and CD28, or by G protein-coupled receptors for chemokines. Analysis of integrin activation induced by CD3/TCR, CD2 and CD28 suggests a critical role for phosphoinositide 3-OH kinase (PI 3-K). This review summarizes recent insights into PI 3-K-dependent regulation of integrin function in leukocytes, including the mechanisms by which these receptors are coupled to PI 3-K, and potential downstream effectors of PI 3-K that regulate integrin-mediated adhesion in leukocytes.

Animals↗
PubMed1999

Role of hemolysis in potassium release by iodinated contrast medium.

It has been demonstrated that an iodinated contrast medium (CM) causes release of potassium into blood vessel lumina, resulting in an increase in serum potassium. The purpose of the present study was to assess whether this potassium release is due to hemolysis. Fresh human blood was mixed in vitro with CM at a ratio of 10:2. Potassium release rates were determined, and serum haptoglobin and free hemoglobin were measured after 30 min of exposure to CM. To compare the potassium release curve between CM exposure and true hemolysis induced by distilled water, fresh human blood was also mixed with distilled water. The level of serum haptoglobin decreased due to hemodilution. Changes in haptoglobin were not correlated with potassium release rates. The serum free hemoglobin level did not increase significantly, and there was no correlation between changes in the free hemoglobin level and the rate of potassium release. Hemolysis caused by water occurred instantaneously, whereas potassium release caused by CM was a slow response, which was linearly correlated with exposure time. Potassium release from blood cannot be explained by hemolysis.

Aged↗
PubMed1999

Immediate increase of portal pressure, reflecting sinusoidal shear stress, induced liver regeneration after partial hepatectomy.

The mechanisms whereby hepatocytes in the normal liver can be primed for replication following partial hepatectomy (PHx) are poorly understood. To determine whether "shear stress," which is induced by acute portal hypertension after PHx, is involved in liver regeneration, we studied liver regeneration in rats with splenic transposition (SPT) in which we can minimize the postoperative elevation of portal pressure. Rats underwent 70% PHx following splenic transposition or sham surgery and were killed at various time points to measure portal pressure and other factors. In the control groups, the portal pressure was significantly increased immediately after surgery, peaking at 48 h, and returning to near the preoperative levels by 168 h after PHx. In the SPT group, although portal pressure increased immediately, it decreased to the control levels 6 h after PHx and thereafter repeatedly increased. Tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) levels peaked at 24 and 6 h after PHx, respectively. Proliferative cell analysis was done using MIB-5 antibody, and there were no significant differences between the two groups. Furthermore, liver weight was restored in the same way in both groups. Taken together, the results suggest that an immediate increase in portal pressure is necessary for the initiation of liver regeneration.

Animals↗
PubMed1999

Bioabsorbable poly-L-lactide costal coaptation pins and their clinical application in thoracotomy.

BACKGROUND: To gain a wider operation field, ribs often are fractured as the intercostal retractor is expanded. Thoracotomy through the periosteal bed and other procedures have been performed to prevent rib fractures, and rib resections occasionally have been required. METHODS: We designed a poly-L-lactide costal coaptation pin. We used this pin in 184 thoracotomies and carried out long-term observation after insertion to evaluate its clinical efficacy and safety. Postoperative observation periods ranged from 1 to 58 months (mean +/-standard error, 21.6+/-1.2 months). We evaluated the costal pin according to its degree of fixation, categorizing it as "good," "fair," or "poor" in this respect. We also judged its lateral shift. RESULTS: We judged fixation as "good" in 130 cases (70.7%), and found no lateral shift in 103 cases (56%). Our overall evaluation indicated satisfactory results in 172 cases (93.5%). CONCLUSIONS: Rib fixation was secured in nearly all cases, and no side effects were encountered. We can confirm that the poly-L-lactide costal coaptation pin is a highly effective and safe device.

Absorbable Implants↗
PubMed1999

Prevention of postoperative air leakage from lungs using a purified human collagen membrane-polyglycolic acid sheet.

BACKGROUND: Human amnion has useful biomedical applications because it contains a large amount of human collagen fibers. We prepared purified human collagen membrane (HCM) from human amnion and used it to develop a new sheet by combining it with synthetic bioabsorbable polyglycolic acid (PGA) mesh. We evaluated its efficacy in preventing air leakage from the lungs of dogs. METHODS: In 20 dogs, HCM-PGA sheet (n = 5), sheets using fibrin glue with a separate application method (n = 5), a mixed application method (n = 5), and fibrin glue alone (n = 5), were used as dressing materials after partial lung resection. RESULTS: The HCM-PGA sheet using fibrin glue with a separate application method was shown to be significantly more effective by an air leakage pressure test than the other three methods. These results indicate that the HCM-PGA sheet is useful for preventing air leakage from the lung. CONCLUSIONS: The HCM-PGA sheet is more effective than conventional fibrin glue for controlling postoperative air leakage.

Amnion↗
PubMed1999

Formation and mineralization of murine molar roots with hypocalcaemia induced by a low-calcium diet and the changes after returning to a normal diet.

The purpose was to examine the formation and mineralization of molar roots in rats with hypocalcaemia, induced by a low-calcium diet and the changes after returning to a normal diet. Two-week-old male Wistar rats were fed a low-calcium diet (0.03% calcium) during the period when the first molar roots form and then a diet containing normal amounts of calcium (1.83% calcium) was restored. The blood calcium, the length and mineralization of the first upper molar roots, and the density of surrounding alveolar bone were measured, and the morphological and histological features of the roots examined. While the rats were fed the low-calcium diet, they had a significantly lower blood calcium than normal controls. Morphologically, the upper first molar roots were shorter and the predentine layer was thicker. The mineralization of dentine and the surrounding alveolar bone was significantly less than in the controls and no mineralization was detected in the thickened predentine. After a normal calcium diet had been restored, the blood calcium, thickness of dentine, alveolar bone density, and length of the roots caught up with the normal. In addition, hypomineralized dentine and interglobular dentine were observed. Subsequently, the mineralization of the dentine increased and the amount of interglobular dentine gradually decreased. These results suggest that in rats a low-calcium diet induces hypocalcaemia, causing the formation of interglobular dentine and hypomineralization of the dentine of the roots. Most physiological variables recovered completely with the return to a normal-calcium diet, although some hypomineralization of the dentine remained.

Animals↗
PubMed1999

Spontaneous conception after the birth of infants conceived through in vitro fertilization treatment.

OBJECTIVE: To investigate the incidence of spontaneous conception after the birth of infants conceived through IVF in couples with subfertility caused by endometriosis, a mild male factor, or unexplained factors, and to identify clinical conditions related to the occurrence of spontaneous conception. DESIGN: Retrospective analysis. SETTING: Department of Obstetrics and Gynecology, Akita University School of Medicine, Akita, Japan. PATIENT(S): One hundred forty-two women who conceived through IVF and 25 of the 142 women who subsequently conceived spontaneously. INTERVENTION(S): Patient characteristics and IVF data were obtained from hospital records, and follow-up data were collected through telephone interviews. MAIN OUTCOME MEASURE(S): Cumulative conception rate. RESULT(S): The cumulative conception rate at 60 months after the delivery of infants conceived through IVF was 18%, with most conceptions occurring within 2 years of delivery. Proportional hazard analysis indicated that patient age was the most important clinical variable related to the occurrence of spontaneous conception. CONCLUSION(S): This study provides information that will be useful in counseling subfertile couples who have conceived through the use of IVF.

Adult↗
PubMed1999

Intrathoracic esophageal replacement in the dog with the use of an artificial esophagus composed of a collagen sponge with a double-layered silicone tube.

OBJECTIVES: Intrathoracic esophageal replacement with an artificial esophagus is considered difficult. We attempted to replace the intrathoracic esophagus with an artificial esophagus composed of a collagen sponge with a double-layered silicone tube and examined the state of host tissue regeneration. METHODS: A 5-cm long gap was created in the intrathoracic esophagus in 9 dogs and repaired by interposition of our prosthesis. The dogs were fed only by intravenous hyperalimentation for 28 days. The silicone tube was removed at 29 days after the operation, and oral feeding was reintroduced. RESULTS: One dog was put to death at each of the following times: 1, 2, 3, 3, 6, 12, and 24 months after the operation. One dog is still surviving without problems after more than 26 months. One dog died of malnutrition at 10 months. In all dogs, the host regenerated tissue had replaced the resulting gap at the time of silicone tube removal. The mucosa had fully regenerated within 3 months and the glands within 12 months. The process of stenosis and shrinkage was complete within 3 months and did not advance thereafter. The lamina muscularis mucosae were observed as islets of smooth muscle within 12 months. Although the skeletal muscle regenerated close to the anastomoses, it did not extend to the middle of the regenerated esophagus even after 24 months. CONCLUSIONS: Use of a collagen sponge with a double-layered silicone tube was shown to be feasible even in the thorax and to allow the regenerated host tissue, consisting of the mucosa, glands, and lamina muscularis mucosae, to replace the esophageal gap.

Anastomosis, Surgical↗
PubMed1999

Serious group A streptococcal infection around delivery.

OBJECTIVE: To differentiate the features of serious, perinatal, group A streptococcal infection from other types of streptococcal toxic shock syndrome. DATA SOURCES: Thirty-eight obstetric cases that were fatal or fulfilled the criteria of Centers of Disease Control and Prevention for streptococcal toxic shock syndrome were reviewed. Three cases were from Asahi General Hospital, 26 from MEDLINE (1966-December 1998), four from Japana Centra Revuo Medicina (1987-November 1998) using the search terms "Streptococcus," "Streptococcus pyogenes," "Streptococcal infection," "pregnancy," "labor," "delivery," "sepsis," and "shock," and five from official records of the Ministry of Health and Welfare of Japan. Cases of early pregnancy or cases that had unclear intervals between delivery and deterioration were eliminated. INTEGRATION AND RESULTS: The 30 cases were divided into two groups by interval between delivery and deterioration. Seventeen cases deteriorated before, during, or within 12 hours of delivery (perinatal group). They were compared with 13 cases of the puerperal group. The mortality rates for infants and mothers in the perinatal group were higher than those of the puerperal group (infant: ten of 17 versus zero of 13, mother: 15 of 17 versus seven of 13). The other differences of description were unusually strong labor (eight of 17 versus one of 13), obvious serious inflammation (zero of 17 versus ten of 13), and evidence of serious sepsis (eight of 17 versus zero of 13). Purulent myometritis without neighboring inflammation was found in our three cases. In ten cases, subjects or their family members had preceding sore throats. CONCLUSION: The cases in the perinatal group had characteristic features. We suspected that after invading the myometrium through the upper respiratory tract, large amounts of cocci were dispersed into the systemic circulation of the mother by active uterine contractions caused by purulent myometritis. Unusual clinical signs were important for diagnosis.

Diagnosis, Differential↗
PubMed1999

Interferon-gamma rescues TNF-alpha-induced apoptosis mediated by up-regulation of TNFR2 on EoL-1 cells.

Recent studies show that apoptosis is important for the resolution of chronic inflammation. Using a human myeloblastic leukemia cell line, EoL-1, we investigated the effect of interferon-gamma (IFN-gamma), which differentiates EoL-1 into monocyte/macrophage-like cells on Fas antigen (Fas)- and tumor necrosis factor-alpha (TNF alpha)-induced apoptosis. Both TNF and anti-Fas monoclonal antibody (CH-11) induced apoptosis of EoL-1 cells. Pretreatment with IFN-gamma for 72 hours enhanced the CH-11-induced apoptosis with up-regulation of Fas. However, the treatment markedly inhibited the TNF-induced apoptosis. In flow cytometric analysis, EoL-1 expressed two types of tumor necrosis factor receptors (TNFR1 and TNFR2), and the expression of TNFR2 but not of TNFR1 was up-regulated significantly after the IFN-gamma treatment. The TNF-induced apoptosis was mimicked by a TNFR1 stimulating antibody (htr-9), and was reversed by a TNFR1 blocking antibody (H398). Although the TNFR1-mediated cytotoxic signal was not affected by IFN-gamma pretreatment, blocking TNFR2 by a specific antagonistic antibody (utr-1) canceled the inhibitory effect of IFN-gamma. In conclusion, TNF-induced apoptosis was mediated preferentially by TNFR1, and the anti-apoptotic effect of IFN-gamma was result from up-regulated TNFR2 in EoL-1 cell line. This cell line is a useful model to provide new insights into crosstalk among Fas/FasL-, TNF-, and IFN-gamma-mediated signaling.

Antibodies, Monoclonal↗
PubMed1999

Outbreak of severe neurologic involvement associated with Enterovirus 71 infection.

Enterovirus 71 has been associated with several outbreaks, as well as sporadic cases, of central nervous system infection and has a worldwide distribution. Seven children with encephalitis and five with aseptic meningitis caused by Enterovirus 71 were seen at Otsu Municipal Hospital during the summer of 1997. The infections were confirmed serologically, although detection of the viral genome in cerebrospinal fluid was unsuccessful. Seven children were diagnosed as having hand-foot-and-mouth syndrome, two were diagnosed as having herpangina, and three patients younger than 12 months old developed no eruptions. The skin or mucosal manifestations of this outbreak demonstrated considerable variation. The Enterovirus 71 strain that caused the outbreak had a strong neurovirulent tendency. Among the patients with encephalitis, symptoms originating from the impairment of diencephalon were seen in four patients, and those originating from cerebellar impairment were seen in two patients. Brain magnetic resonance imaging in one patient revealed an abnormality in the pons. The neurologic manifestations associated with Enterovirus 71 infection may be characterized by involvement of the cerebellum, brainstem, and diencephalon. Enterovirus 71 is one of the pathogenic viruses that cause hand-foot-and-mouth syndrome, as well as a variety of other clinical manifestations. The most important of these is neurologic disease, especially in infants and young children.

Antibodies, Viral↗
PubMed1999

Plasma fibrinogen and its correlates in elderly Japanese men living in Japan and Hawaii.

Plasma fibrinogen levels were determined using comparable methods for 329 Japanese men in Hiroshima Japan, and 3571 Japanese-American men in Honolulu Hawaii, aged 71-93 years. The age-adjusted mean fibrinogen level in Japanese-American men (307 mg/dl) was significantly higher (p<0.0001) than in native Japanese men (270 mg/dl). In multiple linear regression models, the fibrinogen level was associated significantly and positively with white blood cell count (WBC) and total cholesterol, and inversely with HDL cholesterol and hematocrit in both study samples. The strongest association with fibrinogen was shown for WBC, and this association was not mediated through cigarette smoking. The observed difference in fibrinogen levels could not be fully explained by WBC, total and HDL cholesterol, triglyceride, hematocrit, body mass index, and diabetes. Some unmeasured environmental or lifestyle variables such as diet and physical activity may be partly responsible for the observed difference in fibrinogen levels between native Japanese men and Japanese-American men in Hawaii.

Aged↗
PubMed1999

Adenocarcinoma of the gastroesophageal junction in Japan: relevance of Siewert's classification applied to 177 cases resected at a single institution.

BACKGROUND: There had been a lack of international consensus about the definition of cancer of the gastric cardia until Siewert's classification was approved at a consensus conference during the second International Gastric Cancer Congress held in 1997. STUDY DESIGN: A review of the prospective gastric cancer database at Aichi Cancer Center from 1983 to 1992 identified 1,913 gastric carcinoma patients who underwent gastrectomy. These patients were classified retrospectively according to the Siewert classification, and 177 patients who fell into one of the three types form the basis of this study. Survival analyses were performed after stratifying patients by clinicopathologic variables. RESULTS: There were 33 patients with type II and 144 with type III, although none had type I, a type frequently observed in the west. No evidence of a change in the frequency of types II or III cancers (approximately 9.3% overall) among gastric carcinoma patients was observed over the 10-year period. Clinical staging of gastric carcinoma by the TNM classification was found to reflect accurately the prognosis of these patients. There were no longterm survivors among the few patients with metastasis to the perigastric nodes of the distal stomach. CONCLUSIONS: A striking difference in the distribution of types of adenocarcinoma of the gastroesophageal junction was observed in Japan compared with previously reported western data. A subgroup of carcinoma of the proximal stomach identified as types II and III may not require proximal gastrectomy from the viewpoint of sufficient lymphadenectomy.

Adenocarcinoma↗
PubMed1999

Intermittent jaundice in patients with acute leukaemia: a common mutation of the bilirubin uridine-diphosphate glucuronosyltransferase gene among Asians.

The Gly71Arg mutation of the hepatic bilirubin UDP glucuronosyl-transferase (B-UGT) gene associated with Gilbert syndrome prevails among Japanese and its gene frequency is 0.13. Among 20 patients with acute leukaemia, 4 patients showed intermittent unconjugated hyperbilirubinaemia during the course of combined chemotherapy. The Gly71Arg mutation was detected in all 4 patients with hyperbilirubinaemia, but was not found in 16 patients without hyperbilirubinaemia. Two of them were heterozygotes and one was a homozygote for the Gly71Arg mutation, and the other was a compound heterozygote of the Gly71Arg mutation and TA insertion mutation in the TATA box of the B-UGT gene. In addition to the complications leading to hyperbilirubinaemia, including liver damage due to drugs, viral infections or tumour cell infiltrations and alloimmune haemolysis, carrier status for the Gly71Arg mutation should be considered in a patient with leukaemia showing intermittent hyperbilirubinaemia during the course of chemotherapy, especially among Japanese, Koreans and Chinese owing to its prevalence in those populations.

Acute Disease↗
PubMed1999

Theophylline induces apoptosis of the IL-3 activated eosinophils of patients with bronchial asthma.

In bronchial asthma, eosinophils are upregulated and their survival is suggested to be prolonged by the action of some cytokines such as Interleukin (IL)-3, IL-5 and granulocyte-macrophage colony-stimulating factor (GM-CSF). We find here that the survival of eosinophils in the peripheral blood of patients with asthma is correlated with the serum levels of IL-3 but not of IL-5 and GM-CSF. Interestingly, theophylline is revealed to induce apoptosis of the prolonged survival eosinophils by IL-3, as judged by morphological changes and nucleosomal DNA fragmentation. During the apoptosis, caspase-3 in eosinophils stimulated by IL-3 is activated by theophylline. The substrate of caspase-3, poly (ADP-ribose) polymerase (PARP), is cleaved in the eosinophils after theophylline treatment. These results suggest that theophylline is able to induce apoptosis of the IL-3 activated eosinophils in patients with bronchial asthma, and that its clinical effectiveness may be due to the reduction of inflammatory cells in the airway.

Journal Article↗
PubMed1999

Immunocytochemical features of lens after cataract tissue--signalling molecules (growth factors, cytokines, other signalling molecules), cytoskeleton proteins, cellular and extracellular matrix proteins.

UNLABELLED: We examined the immunocytochemical features of after cataract tissue and cataractous lens epithelium prior to cataract surgery and at the time of surgery. METHODS: This study included 23 cases. Antibodies against the following antigens were used: epidermal growth factor (EGF), EGF receptor (EGF-R), fibroblast growth factor (FGF), FGF receptor (FGF-R), transforming growth factor (TGF)-beta, TGF-beta receptor II (TGF-beta -RII), insulin-like growth factor (IGF)II, platelet derived growth factor (PDGF)-AB, interleukin (IL)-6, IL-1 receptor II, tumor necrosis factor (TNF)-alpha, tissue plasminogen activator (TPA), prostaglandin (PG) E2, plasminogen activator inhibitor (PAI)-1, alpha smooth muscle actin (alpha-SMA), keratin, vimentin, myosin, fibronectin, laminin, types I, II, III, IV, V and VI collagen (Col), and lens epithelial cells (LECs). RESULTS: The following substances were present in posterior and anterior capsular fibrosis of after cataract: EGF, EGF-R, FGF, FGF-R, TGF-beta, TGF-beta-RII, IGF-II, PDGF-AB, IL-6, IL-1RII, TNF-alpha, PGE2, PAI-1, alpha-SMA, keratin, fibronectin, laminin, Type I col, Type II to VI col and LECs. Elschnig's pearls of after cataract expressed FGF-R, TNF-alpha, laminin and LECs. Soemmering's ring of after cataract tissue expressed EGF, FGF, FGF-R, IL-1RII, TPA, PAl-1, keratin and LECs. The following substances were present in cataractous lens epithelium prior to cataract surgery: EGF, EGF-R, FGF, FGF-R, TGF-beta-RII, IL-1-RII, TNF-alpha, PAI-1, keratin, laminin and LECs. The following substances were present in the lens epithelium of anterior capsules collected at the time of cataract surgery: EGF, EGF-R, FGF, FGF-R, TGF-beta, TGF-beta-RII, IGF-II, IL-6, IL-1-RII, TNF-alpha, PGE2, keratin, fibronectin, laminin, Type IV Col and LECs. CONCLUSIONS: These results prove that many kinds of signalling molecules and proteins exist in the process of after cataract formation.

Aged↗
PubMed1999

Facial nerve repair using a collagen conduit in cats.

We evaluated facial nerve regeneration using a collagen tube as a nerve conduit in five cats. In three 5 mm of the facial nerve were resected, a collagen tube was implanted, and a 5 mm segment of the opposite facial nerve was resected, reversed 180 degrees, and sutured back as an autologous nerve graft. In one a collagen tube was implanted on one side, and in the remaining one a 5 mm nerve segment was reversed. Histological, electrophysiological, and horseradish peroxidase labelling examinations were carried out 4-24 weeks postoperatively. Histological study showed that the nerve was well vascularised and regenerated. Electrophysiological examination confirmed the recovery of evoked electromyograms through to the regenerated axons. Horseradish peroxidase examination also confirmed restoration of the whole facial nerve. The collagen tube is an efficient nerve conduit.

Animals↗