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Biomedical subjects

H Hamada

Publications and source records attributed to H Hamada.

At least 145 records · Page 8Linked to original sources
PubMed2000

Negative association between Helicobacter pylori infection and reflux esophagitis in older patients: case-control study in Japan.

BACKGROUND: Recent studies have clarified a close association between H. pylori infection and gastritis, peptic ulcer disease, and gastric cancer, but there is little information concerning the relationship between H. pylori infection and reflux esophagitis (RE). We investigated the relationship between H. pylori, RE, and corpus gastritis. SUBJECTS AND METHODS: Ninety-five patients with RE and 190 sex- and age-matched asymptomatic healthy controls demonstrating no localized lesions in the upper GI tract were studied and evaluated for H. pylori infection, histologic gastritis, serum gastrin, and pepsinogens (PGs). RESULTS: H. pylori infection was significantly lower in RE patients than in asymptomatic controls (41% vs. 76%, p <.01). Histologic gastritis of both the antrum and corpus was significantly less frequent (antrum; p <.01, corpus; p <. 01), and serum levels of PGI and the PG I/II ratio were significantly higher in RE patients than in controls (PGI; p <.05, PG I/II ratio; p <.01). When the subjects were divided into two age groups (59 years of age and younger and 60 years of age and older), a significant difference was found only among patients over 60 years of age (29% vs. 85%, p <.01). Among subjects in this age group, gastritis in both the antrum and corpus were significantly milder in RE patients than in controls. Although the prevalence of H. pylori infection was similar between the two groups of patients under 59 years of age, corpus gastritis was significantly milder in patients than in controls (p <.05). CONCLUSIONS: A significantly low prevalence of H. pylori infection was found in RE patients over 60 years of age but not in those under 59 in comparison with sex- and age-matched controls. The relative lack of corpus gastritis might play a role in the pathogenesis of RE in our population through preservation of the acid secretion area.

Age Factors↗
PubMed2000

Clinical features in patients requiring reoperation after failed endoscopic procedures for hydrocephalus.

The aim of this study was to clarify the clinical features of patients at risk of secondary obstruction following endoscopic fenestration. Clinical notes and endoscopic findings for 15 patients treated with endoscopic procedures were retrospectively reviewed. Endoscopic third ventriculostomy (ETV) was performed as initial treatment in 4 patients with non-communicating hydrocephalus, including a neonate with myelomeningocele, and as an alternative to shunt revision in 4 patients. Two patients with non-communicating hydrocephalus caused by tumor or arachnoid cyst were also managed with third ventriculostomy. Four patients with loculated hydrocephalus underwent endoscopic septostomy. A child with an isolated fourth ventricle was treated with endoscopic aqueductoplasty. Of the 15 patients undergoing endoscopic procedure, 4 required reoperation. Of the 10 patients treated with ETV, only the neonate with myelomeningocele required a ventriculoperitoneal shunt because of failure of the initial procedure. Of the 4 patients treated with endoscopic septostomy, 2 children with loculated hydrocephalus following intraventricular hemorrhage (IVH) underwent a second septostomy. In a patient with an isolated fourth ventricle following posthemorrhagic hydrocephalus, recurrence was noted 8 months after the initial procedure. He underwent a second procedure using a stent implanted into the aqueduct to maintain CSF circulation. Sufficient stomal size or implantation of a stent may be required in the under-2-year age group with hydrocephalus accompanied by IVH and associated with myelomeningocele, in whom the risk of secondary obstruction may be high.

Adolescent↗
PubMed2000

In vivo retention of endothelial cells adenovirally transduced with tissue-type plasminogen activator and seeded onto expanded polytetrafluoroethylene.

PURPOSE: Seeding a prosthetic graft with genetically engineered vascular endothelial cells (ECs) has the potential to enhance the graft's antithrombotic properties. However, it has been reported that ECs transduced with tissue-type plasminogen activator (tPA) have very low levels of retention on grafts, probably because of increased proteolytic activity. We examined the retention of human tPA (htPA)-transduced ECs after the cells were seeded onto expanded polytetrafluoroethylene (ePTFE) grafts and implanted into dogs. We also examined the function of secreted htPA in this model. METHODS AND RESULTS: Canine jugular venous ECs were transduced with adenoviral vectors encoding htPA (Adex1CAhtPA) and beta-galactosidase (Adex1CALacZ). There was a positive relationship between the percentage of X-gal ECs staining and the multiplicity of infection (MOI) of Adex1CALacZ. The level of htPA production in vitro increased with the increasing MOI of Adex1CAhtPA, but decreased gradually 4 days after infection. ECs coinfected with Adex1CAhtPA and Adex1CALacZ (htPAEC) or ECs infected with Adex1CALacZ alone (LacZEC) were seeded onto ePTFE grafts at densities equivalent to confluence to visualize retained ECs in an in vivo flow study. The grafts were implanted into canine carotid arteries and harvested after 5 hours of exposure to blood flow. The harvested grafts showed patchy defects in ECs, most of which were covered with mural thrombi. There was no significant difference in retention between htPAEC (29.3% +/- 8.7%) and LacZEC (19.5% +/- 3. 6%). There was a significant negative correlation between the in vivo EC retention on the grafts and the in vitro cellular passage level of ECs (P =.041; r = -.40). htPAEC produced 210.3 +/- 22.2 ng htPA antigen/10(6) cells per 6 hours in vitro and continued to secrete htPA on the harvested graft. CONCLUSIONS: We demonstrated that a large amount of functional htPA was produced by adenovirally modified canine ECs. The results of the in vivo study may suggest that overexpression of tPA has little effect on the short-term retention of early passage ECs seeded onto ePTFE grafts.

Adenoviridae↗
PubMed2000

Relationship between serologically diagnosed chronic atrophic gastritis, Helicobacter pylori, and environmental factors in Japanese men.

BACKGROUND: Whereas chronic atrophic gastritis is known to be an intermediate stage in gastric carcinogenesis, information is sparse about factors associated with this precancerous lesion except for Helicobacter pylori. METHODS: In a cross-sectional study of 566 men aged 50-55 years in the Japan Self-Defense Forces, we examined the relation of H. pylori infection, smoking, alcohol use, and dietary factors to the prevalence of chronic atrophic gastritis as determined by serum pepsinogen I and pepsinogen II (I/II ratio < 3.0. and pepsinogen I < 70 ng/ml). Chronic atrophic gastritis was classified as severe when the pepsinogen I/II ratio was < 2.0, and as moderate otherwise. RESULTS: The overall prevalence of chronic atrophic gastritis was 35.7% (202 of 566). The seropositivity of H. pylori was associated with a 10-fold increase in the risk of chronic atrophic gastritis, and the association was much stronger for moderate atrophic gastritis. Neither cigarette smoking nor alcohol consumption was related to the overall risk of chronic atrophic gastritis. Consumption of vegetables and fruits was each unrelated to chronic atrophic gastritis whether examined as a whole or separately for moderate and severe atrophic gastritis. Green tea was related to decreased risk of severe atrophic gastritis, although not statistically significant, whereas garlic consumption showed no protective association. CONCLUSIONS: The findings corroborate that H. pylori infection has an important role in the development of chronic atrophic gastritis in middle-aged Japanese men. Green tea consumption may be protective against the advance of atrophic gastritis. Vegetables, fruits, or garlic had no protective effect against the development of atrophic gastritis in the study.

Alcohol Drinking↗
PubMed2000

The antiangiogenesis effect of interleukin 12 during early growth of human pancreatic cancer in SCID mice.

Interleukin 12 (IL-12) is a heterodimeric cytokine that exerts a potent antitumor effect through its pleiotropic actions. It was recently reported that IL-12 has also a potent antiangiogenic effect through the induction of IFN-gamma, which triggers the production of chemokines such as IP-10 that has been shown to have antiangiogenesis properties. In this study we transfected the IL-12 gene into a human pancreatic adenocarcinoma cell line (PK-1). PK-1 cells transfected with the green fluorescence protein (gfp) gene were used as positive controls. The in vitro growth curve and in vivo tumor growth of transfectants (IL-12/PK-1 and gfp/PK-1) were compared with those of parental cells. The SCID mice used in this study were administered antiasialo GM-1 Ab (100 microg, i.p., twice weekly) to deplete the remaining immunoeffector cells, NK cells. Using a skinfold chamber model, we observed and recorded tumor angiogenesis by intravital microscopy. In vitro growth of IL-12/PK-1 and gfp/PK-1 cells was not different from that of wild-type PK-1 cells (wt/PK-1). However, IL-12 transfected PK-1 cells did not develop into tumors as did the wt/PK-1 cells after subcutaneous inoculation in antiasialo GM-1 Ab administered SCID mice. The growth of IL-12/PK-1 tumors was restored in mice treated with anti-IL-12 antibody. We found that IL-12/PK-1, in contrast to gfp/PK-1 and wt/PK-1, failed to initiate an angiogenic response, as observed in the skinfold chamber model. These results indicate that the antiangiogenesis effect of IL-12 alone, without immune system involvement, is sufficient to block the growth of human pancreatic cancer.

Adenocarcinoma↗
PubMed2000

Adenovirus-mediated gene transduction of IkappaB or IkappaB plus Bax gene drastically enhances tumor necrosis factor (TNF)-induced apoptosis in human gliomas.

Tumor necrosis factor-alpha (TNF), which was initially supposed to be a promising cancer therapeutic reagent, does not kill most types of cancer cells partly due to the activation of an anti-apoptotic gene, NF-kappaB. NF-kappaB forms an inactive complex with the inhibitor kappa B alpha (IkappaBalpha), which is rapidly phosphorylated and degraded in response to various extracellular signals. To disrupt this protective mechanism, we introduced an inhibitor kappa B alpha (IkappaBdN) gene, a deletion mutant gene lacking the nucleotides for the N-terminal 36 amino acids of IkappaBalpha, into human glioma cells (U251, T-98G, and U-373MG) via an adenoviral (Adv) vector in addition to treatment of the glioma cells with recombinant TNF. Immunohistochemical analysis revealed that NF-kappaB was translocated to nuclei by TNF treatment in U251 and T-98G cells, but not in U-373MG cells. Neither transduction of IkappaBdN nor treatment with TNF protein alone induced apoptosis in U251 and T-98G cells, whereas both cell lines underwent drastic TNF-induced apoptosis after transduction of IkappaBdN. On the other hand, U-373MG cells were refractory to TNF-induced apoptosis even when they were transduced with the IkappaBdN gene. U-373MG cells underwent drastically increased apoptosis when co-transduced with the IkappaBdN and Bax gene in the presence of TNF. Adv-mediated transfer of IkappaBdN or IkappaBdN plus Bax may be a promising therapeutic approach to treat gliomas through TNF-mediated apoptosis.

Adenoviridae↗
PubMed2000

Transduction of a fiber-mutant adenovirus for the HSVtk gene highly augments the cytopathic effect towards gliomas.

Suicide gene therapy utilizing the herpes simplex thymidine kinase (HSVtk) / ganciclovir (GCV) system has been performed to kill cancer cells. However, the low transduction efficiency of HSVtk gene into cancer cells critically limits its efficacy in cancer treatment in clinical situations. To improve delivery of the HSVtk gene into cancer cells, we transduced U-87MG and U-373MG glioma cells with adenovirus (Adv) vectors with a fiber mutant, F / K20, which has a stretch of 20 lysine residues added at the C-terminus of the fiber, for the HSVtk gene (Adv-TK-F / K20), and compared the cytopathic effect of Adv-TK-F / K20 with that of the Adv for HSVtk with wild-type fiber (Adv-TK). The cytopathic effect of Adv-TK-F / K20 in U-87MG and U-373MG cells was approximately 140 and 40 times, respectively, stronger than that of Adv-TK. At the same multiplicity of infection (MOI) in each cell line, Adv-TK-F / K20 induced a higher degree of apoptosis (U-87MG, 35%; U-373MG, 77%) than Adv-TK (U-87MG, 0.11%; U-373MG, 27%) in U-87MG (MOI 0.03) and U-373MG cells (MOI 0.1). Cleavage of poly(ADP-ribose)polymerase (PARP) was more marked in the cells that were infected with Adv-TK-F / K20 than in cells that were infected with Adv-TK. These results indicate that gene therapy utilizing Adv-TK-F / K20 may be a promising therapeutic modality for the treatment of gliomas.

Adenoviridae↗
PubMed2000

Adenovirus-mediated transfer of Fas ligand gene augments radiation-induced apoptosis in U-373MG glioma cells.

Most malignant astrocytomas (gliomas) express a high level of Fas, whereas the surrounding normal tissues such as neurons and astrocytes express a very low level of Fas. Thus, transduction of Fas ligand would selectively kill malignant astrocytoma cells. On the other hand, glioma cells harboring p53 mutation have been reported to be resistant to conventional therapies including radiation. To override the resistance mechanism of glioma cells with p53 mutation to radiation, we transduced U-373MG malignant astrocytoma (glioma) cells harboring mutant p53 with Fas ligand via an adenovirus (Adv) vector in combination with X-ray irradiation, and evaluated the degree of apoptosis. The degree of apoptosis in U-373MG cells infected with the Adv for Fas ligand (Adv-FL) and treated with irradiation (81%) was much higher than that in U-373MG cells infected with Adv-FL and not treated with irradiation (0.8%) or that in U-373MG cells infected with the control Adv for lacZ and treated with irradiation (5.0%). In U-373MG cells infected with Adv-FL, irradiation increased the expression of Fas ligand. Coincident with the increase in Fas ligand, there was a marked reduction in the caspase-3 level and a marked increase in the cleaved form of poly(ADP-ribose) polymerase (PARP), which are downstream components of Fas ligand-mediated apoptosis. This suggests that the enhanced activation of caspase-3 by the transduction of Fas ligand combined with irradiation, induced extensive apoptosis in U-373MG cells. In summary, transduction of Fas ligand may override the resistance mechanism to radiotherapy in glioma cells harboring p53 mutation.

Adenoviridae↗
PubMed2000

Resolution of front-back confusion in virtual acoustic imaging systems.

A geometric model of the scattering of sound by the human head is used to generate a model of localization cues based on interaural time delay (ITD). The ITD is calculated in terms of the interaural cross-correlation function (IACC) for sources placed at a series of azimuthal angles in the horizontal plane. This model is used to simulate the pressures generated at the ears of a listener due to real sources and due to a two-channel and a four-channel virtual source imaging system. Results are presented in each case for the variation of ITD with head rotation. The simulations predict that the rate of change of the ITD with head rotation produced by a real source and replicated by the four-channel virtual source imaging system, cannot be replicated by the two-channel system. These changes to the ITD provide cues which allow resolution of front-back confusion. The results of subjective experiments are also presented for the three cases modeled. These results strongly support the findings from the modeling work indicating that, for the systems described here, front-back confusion is resolved through changes to the ITD arising from head motion.

Attention↗
PubMed2000

Effect of suplatast tosilate (IPD-1151T) on a mouse model of asthma: inhibition of eosinophilic inflammation and bronchial hyperresponsiveness.

BACKGROUND: Suplatast tosilate (IPD) is a newly developed 'anti-allergic' drug. It seems to be a unique compound because of its ability to suppress IgE but not IgG or IgM production in vivo and cytokine production from type 2 helper T cells (Th2) in vitro. However, information on its in vivo effect on an animal model of asthma is limited. METHOD: BALB/c mice sensitized to ovalbumin (3 times, 2-week interval) were challenged with ovalbumin by inhalation (50 mg/ml for 20 min, once a day for 6 days). In this study, we explored the influence of IPD on eosinophil infiltration into the airways, bronchial hyperresponsiveness (BHR) to methacholine, specific IgE antibody production, and cytokines in bronchoalveolar lavage fluid (BALF) using this murine model. RESULTS: Treatment with IPD significantly reduced the number of total cells and eosinophils in BALF (around -40%) and almost completely inhibited the development of antigen-induced BHR. Histological findings confirmed the reduction of submucosal cell infiltration in the lung, and disclosed the marked inhibition of bronchial epithelial cell damage. Ovalbumin-specific IgE was slightly but significantly reduced. The levels of IL-4, IL-5 and IL-13 in BALF were significantly decreased in mice treated with the compound compared to those in untreated mice. CONCLUSION: These results suggest that IPD is capable of inhibiting the production of Th2 cytokines, which inhibit eosinophil infiltration into the murine airway, IgE synthesis, and development of BHR, in a murine model of asthma.

Animals↗
PubMed2000

Mast cell basic fibroblast growth factor in silicosis.

To investigate the role of mast cells (MC) and their fibrogenic growth factors in silicosis, we performed quantitative immunohistochemistry for MC tryptase and for basic fibroblast growth factor (bFGF) in lung tissue from silicotic and control subjects. Anti-bFGF antibody was bound to lung MC, basement membrane, endothelial cells, and smooth-muscle cells. Morphometric analysis revealed that the volume density (V(v)) of MC was increased in silicotic lung and that the V(v) of bFGF-positive (bFGF(+)) cells was significantly higher than normal in silicotic lung. Most MC contained bFGF (rho = 0.88, p < 0.001). The V(v) of collagen/reticulin fibers was increased in silicosis and correlated with the V(v) of bFGF(+) cells (rho = 0.81, p < 0.001). Immature silicotic nodules contained bFGF(+) MC throughout the loose array of collagen/reticulin fibers. In large, mature nodules, the density of collagen/reticulin fibers was higher, and bFGF(+) MC were found only in the nodule periphery. Because of this circumferential MC alignment in silicotic nodules, we observed a negative correlation between the V(v) of bFGF(+) MC and the density of collagen/reticulin fibers in silicotic nodules (rho = -0.80, p < 0.001) and between the V(v) of all other nodule-associated cells and the density of collagen/reticulin fibers in the hypocellular nodule centers (rho = -0.84, p < 0.001). We conclude that MC that produce bFGF may play an important role in the development of silicosis.

Aged↗
PubMed2000

Activin/nodal responsiveness and asymmetric expression of a Xenopus nodal-related gene converge on a FAST-regulated module in intron 1.

Vertebrate Nodal-related factors play central roles in mesendoderm induction and left-right axis specification, but the mechanisms regulating their expression are largely unknown. We identify an element in Xnr1 intron 1 that is activated by activin and Vg1, autoactivated by Xnrs, and suppressed by ventral inducers like BMP4. Intron 1 contains three FAST binding sites on which FAST/Smad transcriptional complexes can assemble; these sites are differentially involved in intron 1-mediated reporter gene expression. Interference with FAST function abolishes intron 1 activity, and transcriptional activation of Xnrs by activin in embryonic tissue explant assays, identifying FAST as an essential mediator of Xnr autoregulation and/or 'signal relay' from activin-like molecules. Furthermore, the mapping of endogenous activators of the Xnr1 intronic enhancer within Xenopus embryos agrees well with the pattern of Xnr1 transcription during embryogenesis. In transgenic mice, Xnr1 intron 1 mimics a similarly located enhancer in the mouse nodal gene, and directs FAST site-dependent expression in the primitive streak during gastrulation, and unilateral expression during early somitogenesis. The FAST cassette is similar in an ascidian nodal-related gene, suggesting an ancient origin for this regulatory module. Thus, an evolutionarily conserved intronic enhancer in Xnr1 is involved in both mesendoderm induction and asymmetric expression during left-right axis formation.

Activins↗
PubMed2000

Stereocontrolled reduction of alpha- and beta-keto esters with micro green algae, Chlorella strains.

The stereocontrolled reduction of alpha- and beta-keto esters using micro green algae was accomplished by a combination of the cultivation method and the introduction of an additive. The reduction of ethyl pyruvate and ethyl benzoylformate by the photoautotrophically cultivated Chlorella sorokiniana gave the corresponding alcohol in high e.e. (>99% e.e. (S) and >99% e.e. (R), respectively). In the presence of glucose as an additive, the reduction of ethyl 3-methyl-2-oxobutanoate by the heterotrophically cultivated C. sorokiniana afforded the corresponding (R)-alcohol. On the other hand, the reduction in the presence of ethyl propionate gave the (S)-alcohol. Ethyl 2-methyl-3-oxobutanoate was reduced in the presence of glycerol by the photoautotrophically cultivated C. sorokiniana or the heterotrophically cultivated C. sorokiniana to the corresponding syn-(2R,3S)-hydroxy ester with high diastereo- and enantiomeric excess (e.e.). Some additives altered the stereochemical course in the reduction of alpha- and beta-keto esters.

Chlorella↗
PubMed2000

Secretion of adrenocorticotropic hormone induced by allergen inhalation in patients with atopic asthma.

Allergen inhalation in atopic patients results in cytokines production or release of preformed cytokines, some of which are known to induce adrenocorticotropic hormone (ACTH) secretion in experimental conditions. We examined whether allergen inhalation can induce ACTH secretion in vivo. A significant elevation of ACTH levels was observed in 2 and 24 hr after allergen inhalation challenge. However, methacholine challenge with the same degree of airflow limitation did not induce ACTH elevation, indicating that this may not be due to bronchoconstriction per se. Our results indicate that allergen inhalation can trigger ACTH secretion in patients with atopic asthma.

Adrenocorticotropic Hormone↗
PubMed2000

[A case of pneumonia caused by Mycobacterium avium complex successfully treated with clarithromycin].

We reported on a 79-year-old woman with pneumonia caused by Mycobacterium avium complex (MAC). She was admitted with fever, general fatigue, and cough. A chest X-ray film showed infiltrative shadows in the right lung field. In spite of administration of conventional antibiotics, the infiltrative shadows enlarged. A chest CT scan revealed areas of consolidation and ground glass opacities. Bronchoalveolar lavage (BAL) examination revealed an increased number of lymphocytes. Transbronchial lung biopsy revealed many granulomatous regions with giant cells. Mycobacterium intracellulare was found in the culture of BAL fluid and identified by PCR. Treatment was started with rifampicin, ethambutol, and clarithromycin. However, rifampicin and ethambutol were soon discontinued because of severe anorexia. Her symptoms and the radiographic appearance markedly improved following treatment of clarithromycin alone. Subsequently small doses of rifampicin and ethambutol were restarted because her general condition was much improved. These findings suggest that clarithromycin is an effective and tolerable agent for elderly patients with MAC.

Aged↗
PubMed2000

Serotonin and pancreatic duct function.

1. 5-HT inhibits spontaneous fluid secretion as well as stimulated secretion with secretin (cAMP mediated) or ACh (Ca2+ mediated) in the isolated guinea pig pancreatic ducts. 2. The inhibitory effect of 5-HT is reversible and is dependent on the concentration in the range 0.01-0.1 microM, which is much lower than those that affect intestinal motility and secretion. 3. The 5-HT3 receptor in duct cells appears to mediate the inhibitory effect of 5-HT. 4. [Ca2+]i is unlikely to mediate the inhibitory effect of 5-HT.

5-Methoxytryptamine↗
PubMed2000

[Evaluation with blink reflex of bilateral facial palsy].

We examined the accuracy of electroneuronography (ENoG) and blink reflex as prognostic indicators in four patients with bilateral facial palsy. Electrophysiological investigation consisted of the recording of ENoG amplitude and R1 amplitude of blink reflex elicited by the peripheral nerve stimulation. Examinations were performed at the first visit, after 10 days, 2, 4 and 6 weeks. ENoG amplitude was less reliable for the neurological evaluation of bilateral facial palsy, because in three cases amplitude ratio of affected side to the other side was more than 100%. R1 amplitude of blink reflex recovered satisfactorily in two cases of good outcome. In other two cases of poor outcome, R1 amplitude was absent during the examination period. These findings suggest that analysis of blink reflex provides valuable information for evaluation of the prognosis of patients with bilateral facial palsy.

Adult↗