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Biomedical subjects

K Mitamura

Publications and source records attributed to K Mitamura.

At least 73 records · Page 4Linked to original sources

Enzymatic hydrolysis of the conjugate of vitamin D and related compounds.

The monoglucuronides of vitamin D, 25-hydroxyvitamin D and the corresponding pro-forms were subjected to enzymatic hydrolysis using beta-glucuronidase, and substrate specificities were found in the examined enzymes originating from different sources, which were determined using reversed-phase high-performance liquid chromatography with UV detection. The enzymatic hydrolysis of the corresponding monosulfates was also examined using the same system.

Chromatography, High Pressure Liquid↗

Detection of Epstein-Barr virus-encoded small RNA 1 and latent membrane protein 1 in synovial lining cells from rheumatoid arthritis patients.

Several investigators have demonstrated an association between Epstein-Barr virus (EBV) and the pathogenesis of rheumatoid arthritis (RA). However, there is no direct evidence that this virus exists in the synovial cells of patients with RA. We attempted to detect EBV in synovial cells from RA patients. Specimens of synovial tissues from 34 patients with RA and from 20 patients with osteoarthritis (OA), and from one patient with psoriatic arthritis as controls, were examined for evidence of the EBV by in situ hybridization. The specimens were also tested by immunoperoxidase staining for expression of the CD21 molecule (EBV receptor), EBV nuclear antigen (EBNA)-2 and latent membrane protein (LMP)-1. EBV-encoded small RNA-1 (EBER) was demonstrated in synovial lining cells from eight (23.5%) out of 34 RA patients but in none of 20 OA patients (P < 0.05) nor in the one psoriatic arthritis patient. Interestingly, EBER localized in synovial lining cells that were located at the apex of villus proliferating lesions. Furthermore, LMP-1 was also detected in synovial lining cells at the top of villus lesions. Nevertheless, CD19 and CD21 molecules, and EBNA-2 were not demonstrated in such lesions. The incidence of EBV-positive in synovial lining cells with severely infiltrated lymphocytes tended to be higher than that in moderately infiltrated ones. This is the first evidence that EBV exists in chronically inflamed synovial lining cells of human joints in RA.

Antigens, Viral↗

In vitro glucuronidation of 25-hydroxyvitamin D3 and its pro-form.

In vitro glucuronidation of 25-hydroxyvitamin D3 and its pro-form has been investigated by means of HPLC with UV detection. Although both substrates gave 3- and 25-glucuronides in the presence of the rat liver microsomal fraction and uridine-5'-diphosphoglucuronic acid, 25-hydroxyvitamin D3 and its pro-form yielded 3- and 25-glucuronide as the main product, respectively. The latter glucuronide is the one in which the tert-hydroxy group is conjugated. Each glucuromide was identified by its chromatographic behavior in comparison with an authentic sample and data obtained from liquid chromatography/mass spectrometry (LC/MS) using atmospheric pressure chemical ionization.

Animals↗

[Interferon treatment for hepatitis G virus infection in patients with chronic hepatitis C].

Clinical features of HGV infection as a novel virus infection have not yet been clarified enough. We studied the implication of HGV in the activity of hepatitis and the sensitivity of HGV to IFN. We treated 10 HGV RNA positive patients with chronic hepatitis C with IFN. HGV RNA was identified in serum by RT-PCR method using the primer derived from the base sequences of the NS5 region of HGV genome. HGV RNA became negative in the all of 10 patients during IFN treatment, but returned to be positive again in the all patients after the completion of IFN treatment. In 5 of 10 patients, HCV RNA became persistently negative. In 3 of these 5 patients, ALT was continuously normal and hepatitis subsided biochemically and clinically after IFN treatment. We assume that HGV is sensitive to IFN, but could not be implicated in hepatitis or liver damage.

Adult↗

[Depression during interferon therapy in chronic hepatitis C patients--a prospective study].

The number of patients treated with interferon (IFN) has increased markedly in Japan since 1992, when the Health and Welfare Ministry approved the use of IFN for treating chronic active hepatitis C. It is important to identify and treat depression, which is one of the psychiatric complications of IFN therapy and often leads to discontinuation of the therapy, in patients with chronic hepatitis C. In this study we prospectively investigated the incidence of depression during IFN therapy in patients with chronic active hepatitis C. The psychiatric status of 85 patients (53 men, 32 women; mean age 49.1 years) with chronic active hepatitis C who began receiving IFN at Showa University Hospital was assessed before and 2, 4, 12 and 24 weeks after the start of IFN therapy, using the major depressive episode diagnostic criteria listed in the DSM-III-R and the Hamilton Depression Scale HDS). All of the patients provided informed consent prior to participation in this study. IFN therapy was discontinued in 5 cases (5.9%) because of physical side effects and in 4 cases (4.7%) because of depression. Two, 11, 14, 25 and 16 patients were diagnosed as having major depressive episodes before and 2, 4, 12 and 24 weeks after the start of IFN therapy, respectively. The number of patients who were asymptomatic before the start of IFN therapy but were diagnosed as having a major depressive episode at least once during IFN therapy was 31 (31/83 = 37.3%). The mean HDS scores at 2, 4, 12 and 24 weeks (5.4, 6.0, 8.8 and 6.6) were significantly higher than that before the start of IFN therapy (3.0). The patients whose first diagnosed major depressive episodes occurred more than 4 weeks after the start of IFN therapy tended to be more severely depressed than those in whom it occurred less than 4 weeks after the start of IFN therapy. Compared to the 47 patients who completed 24 weeks of IFN therapy without experiencing depression, the 31 patients who were diagnosed as experiencing major depressive episodes during IFN therapy had significantly higher neuroticism scores determined using the Eysenck Personality Questionnaire, showed a more severely depressed mood and experienced more severe sleep disturbances before the start of IFN therapy. The latter group of patients also tended to have comorbid chronic physical disorders such as hypertension or diabetes mellitus and the histories of mental disorders before the IFN therapy; however these differences were not statistically significant. There were no differences between the two groups in patient age or sex, the severity of hepatitis before the IFN therapy, the type of IFN used in the therapy or the efficacy of IFN in the treatment of the hepatitis C. Our results indicate that the decision as to whether to treat chronic active hepatitis C with IFN should be made carefully and that early intervention and careful monitoring of depression are required during IFN therapy in the treatment of chronic active hepatitis C.

Adult↗

Evaluation of rectal mucosal hemodynamics in patients with liver cirrhosis using reflectance spectrophotometry.

OBJECTIVES: Portal hypertensive colonopathy is observed in patients with liver cirrhosis. To determine the correlation between rectal mucosal hemodynamics and portal hypertensive colonopathy, we observed rectal mucosal findings and measured rectal mucosal hemodynamics in patients with liver cirrhosis. METHODS: Thirty-four patients with liver cirrhosis and 16 healthy control subjects were simultaneously examined for rectal mucosal findings by colonoscopy and indices of rectal mucosal Hb concentration (RHb) and rectal mucosal oxygen saturation by reflectance spectrophotometry. Endoscopic findings in the rectal mucosa of patients with liver cirrhosis included vascular ectasias, blue veins, and varices. We investigated the relationship between rectal mucosal hemodynamics and clinical parameters of liver cirrhosis (Child-Pugh classification, the amount of indocyanine green remaining in the blood 15 min after its injection, and ascites). Patients with hepatocellular carcinoma, colonic cancer, multiple colonic polyps, or severe anemia were excluded. RESULTS: Rectal mucosal lesions were observed in 11 patients with liver cirrhosis (32.4%). In the hemodynamic studies, we found significantly increased RHb values in the cirrhosis group as compared with the control group. On the other hand, there was no significant change in rectal mucosal oxygen saturation between the two groups. A significant increase in RHb was observed in patients with rectal mucosal lesions in the cirrhosis group. RHb in the cirrhosis group correlated with grade of Child-Pugh classification. Increased RHb decreased in parallel after portal decompression by creation of a transjugular intravenous portosystemic stent shunt. CONCLUSIONS: The rectal mucosal lesions in liver cirrhosis correlate with an increase in RHb, which correlates with portal hypertension.

Ascites↗

[Efficacy and safety of sulbactam/cefoperazone for hepato-biliary infections].

We studied efficacy and safety of sulbactam/cefoperazone (SBT/CPT) in the treatment of biliary tract infections in hospitalized patients at 26 hospitals from February 1993 to March 1995. Secondary to dropout, 273 out of 338 patients entered in the study were evaluated, 127 patients with cholecystitis, 132 patients with cholangitis, and 14 patients with liver abscesses. Of these, 93 patients (34.1% had malignancy as an underlying disease. SBT/CPZ had an efficacy of 79.9% (218 patients; excellent: 52, good: 166), with the efficacy in patients with cholecystitis, cholangitis and liver abscess at 89.0% (113 patients), 77.3% (102 patients and 21.4% (3 patients), respectively. A significant difference (p < 0.05) was observed in the efficacy rates of patients with (59 patients [63.4%]) and without malignancy (159 patients [88.3%]). A total of 84 strains were isolated from bile specimens of 53 patients, and the major isolates were Escherichia coli, Pseudomonas aeruginosa and Enterococcus spp. Two or more bacterial strains were isolated simultaneously in 20 patients. Mild or moderate side effect (allergic reaction including rash etc.) were noted in 4 patients (1.18%), and laboratory abnormalities (increased GOT, etc.) were in 16 patients (4.71%) out of the total 338 patients. This study clearly demonstrated that SBT/CPZ retains its excellent clinical efficacy and safety profile, throughout its use over the past decade.

Adolescent↗

V gene sequences of human anti-ssDNA antibodies secreted by lupus-derived CD5-negative B cell hybridomas.

V gene sequences encoding two lupus-derived human monoclonal IgMk anti-ssDNA antibodies (2F7 and 1A6) and CD5 mRNA expression by the corresponding hybridomas were investigated. Both antibodies displayed V gene sequences nearly in germline configuration compared with their putative germline counterparts. It appeared that 2F7 used hv3019b9/HUD-3/JH6 and 12La/Jk2, while 1A6 utilized HHG19/D31-HUD-3/JH2 and Humkv328h5/Jk1. Assessment of R/S mutation ratios suggested that 2F7 and 1A6 have not undergone the antigen-driven somatic mutation. The HCDR3 featuring arginine appeared to be important in determining the anti-ssDNA specificity. CD5 mRNA was negative in both hybridomas. Since 2F7 was previously shown to be monospecific and of high affinity, these results provide the molecular basis of such unique immunochemical characteristics of the IgM anti-ssDNA antibody. Germline V genes and N sequences may be selected to confer such anti-ssDNA specificity during V gene rearrangement, which might involve CD5-negative B cells.

Amino Acid Sequence↗

Hemodynamics in the colonic mucosa of rats with dextran sulfate-induced colitis in the early phase.

We investigated hemodynamics in the colonic mucosa of rats with experimental colitis induced by the administration of dextran sulfate sodium (DSS). As parameters of hemodynamics, we determined the indices of mucosal hemoglobin concentration (IHb) and mucosal oxygen saturation (ISO2), measured by reflectance spectrophotometry, and an index of colonic mucosal blood flow (Flow), measured by laser-Doppler flowmetry. In the ascending colon, each parameter was measured by a combination of these methods after 1, 3, 5, 7, and 10 days of DSS administration. Histopathological examination was also performed. IHb in the DSS group increased with time; on the 7th day, the value was 126.9 +/- 8.32, while that in the control group was 85.0 +/- 4.14, IHb in the DSS group being significantly increased (P < 0.02). ISO2 in the DSS group was lower than that in the control group, and on the 7th day, was significantly lower in the DSS group (25.7 +/- 1.34) than in the control group (33.4 +/- 1.77) (P < 0.01). No changes in Flow were observed in either the DSS or the control group during the administration period, and no significant difference in Flow was found between the two groups. On histopathological examination, we observed a time-dependent increase in the infiltration of inflammatory cells in the ascending colon of rats treated with DSS, but changes such as erosion and ulceration were not found in the superficial layer of the mucosa. No histopathological changes were found in the control animals. In the early phase of the experimental colitis, hemodynamic alterations in the colonic mucosa were already present at the time the slight histopathological changes developed. These observations seemed to indicate the involvement of hemodynamic alterations in the subsequent tissue injury.

Animals↗

Effect of a cholecystokinin receptor antagonist (loxiglumide) on gallbladder contractile function in guinea pigs.

We evaluated the effect of the specific cholecystokinin (CCK) receptor antagonist, loxiglumide, on gallbladder contractile function in guinea pigs. Five mg/kg body weight (BW) of loxiglumide was administered orally to guinea pigs once a day for 3 days. We then investigated gallbladder contractile function and plasma CCK concentrations in the guinea pigs. Maximal gallbladder pressure induced by cerulein was significantly depressed on the 1st and 3rd days following loxiglumide administration. On the 1st day, the plasma CCK concentration was significantly increased compared with that of the control group during fasting and 15 min after the administration of an intraduodenal test meal. These results suggest that the disturbed gallbladder contraction is due to the competitive inhibition of CCK by loxiglumide. Gallbladder contractile function in guinea pigs is depressed by loxiglumide; however, this effect is reversible after short-term loxiglumide administration.

Animals↗

Cultivation of hepatitis C virus in primary hepatocyte culture from patients with chronic hepatitis C results in release of high titre infectious virus.

To investigate the viral replication cycle and genomic heterogeneity of hepatitis C virus (HCV), we established an HCV cultivation system by using a primary hepatocyte culture from patients with chronic hepatitis C. Liver tissue was obtained by needle biopsy or surgery, then hepatocytes were isolated by collagenase digestion. After several weeks, we determined the HCV RNA titre of the cultured cells and supernatant by a competitive polymerase chain reaction (PCR) method. A significant amount of HCV RNA was observed in the cells and supernatant during cultivation. Negative-strand RNA, regarded as a marker of viral replication, could be detected by a strand-specific reverse transcription PCR method and the HCV core protein could be detected by immunofluorescence microscopy. Many HCV particles released into the supernatant were infectious. In addition, we compared the nucleotide sequences in the E2/NS1 region of pre- and post-cultivation hepatocytes for 8 weeks. At the beginning of the culture period, three major HCV types containing two subtypes were isolated. Following cultivation, the same types were isolated from the cultured hepatocytes in the same ratio as prior to cultivation. We could detect the same clones in this patient's serum, but in vivo we observed genetic variability over a 6 month interval. One clone detected throughout the 6 month period mutated extensively in the hypervariable region. These results indicated that HCV can replicate in cultured hepatocytes, and that infectious virions are released into the supernatant. This cultivation system should facilitate the study of HCV genomic heterogeneity, infection and replication.

Adult↗

Role of sulfatides in adhesion of Helicobacter pylori to gastric cancer cells.

We have demonstrated that clinical isolates of Helicobacter pylori preferentially bind to sulfatides (I3SO3-GalCer) and GM3 gangliosides (II3NeuAcLacCer), two predominant acidic glycosphingolipids in the human gastric mucosa, on thin-layer chromatography plates. However, it has not yet been clarified that these glycospingolipids truly serve as adhesion receptors for H. pylori in live cells. In this study, we used a gastric cancer cell line, KATO III, as a cellular model of H. pylori adhesion and examined the role of sulfatides in attachment. The adhesion of H. pylori (i.e., a standard strain of H. pylori, NCTC 11637) to KATO III cells and the effects of various substances on this adhesion were monitored and semiquantitated by flow cytometric analysis. Sulfated glycoconjugates, such as heparin and gastric mucin, significantly inhibited H. pylori adhesion to KATO III cells. Membrane preparations from KATO III cells strongly inhibited this adhesion. In the membrane preparations, sulfatides were present as a major acidic glycosphinoglipid. With the exception of sulfatides, no distinct adhesion of H. pylori to glycospingolipids from KATO III cells were observed. Moreover, H. pylori did not bind to any membrane proteins of KATO III cells. Finally, a monoclonal anti-sulfatide antibody markedly reduced H. pylori adhesion to KATO III cells. These results suggest that sulfatides, and possibly related sulfated compounds, serve as a major receptor for cell adhesion by H. pylori.

Bacterial Adhesion↗

Binding affinity and quantity of estrogen receptor in peripheral blood monocytes of patients with systemic lupus erythematosus.

Binding affinity and quantity of the estrogen receptor in monocytes of patients with systemic lupus erythematosus (SLE) were studied. The tritiated-estradiol binding assay was performed using peripheral blood adherent cells (> 95% monocytes) derived from six lupus patients (SLEDAI score: 2-30) and five age-comparable normal women during the mid-follicular phase of the menstrual cycle. Dissociation constant (Kd) and number of binding sites (Ro) were estimated by Scatchard analysis. The specificity and sensitivity of the assay were verified by using estrogen receptor-positive ZR75-1 human breast cancer cells. Kd and Ro of the type I receptor for the SLE patients were 12.2 +/- 6.5 (nM) and 69.0 +/- 42.4 (x 1000/cell), respectively, while those of the normals were 14.5 +/- 3.7 and 86.8 +/- 23.4, respectively. Three patients displayed relatively low Kd or Ro values. While those low values fell within the mean -3s.d. of the normal controls, precise statistical comparison was not possible. No clear correlation between the receptor parameters and the SLEDAI scores was noted. Although further studies of a larger number of samples are needed to conclude, these results suggest that peripheral blood monocytes of SLE patients express the estrogen receptor whose Kd and Ro are similar to those of normals.

Adult↗

Separation and characterization of monoglucuronides of vitamin D(3) and25-hydroxyvitamin D(3) in rat bile by high-performance liquid chromatography.

The separation and characterization of vitamin D(3)- and 25-hydroxyvitamin D(3)-monoglucuronides, biliary metabolites obtained from rats dosed with D(3) and 25-hydroxyvitamin D(3) per os, respectively, were carried out by HPLC. The glucuronide fractions were obtained from bile specimens by the combined use of a Bond Elut C18 cartridge, for solid phase extraction, and a lipophilic gel (piperidinohydroxypropyl Sephadex LH-20), for ion-exchange chromatography. Each glucuronide was identified by comparison with an authentic sample in three ways: its chromatographic behavior, that of its fluorescent labeled derivative using 4-[4-(6-methoxy-2-benzoxazolyl)phenyl]-1,2,4-triazoline-3,5- dione and data obtained following enzymatic hydrolysis using beta-glucuronidase.

Animals↗

Long-term prognosis of chronic hepatitis C after treatment with interferon alpha 2b and characterization of incomplete responders.

OBJECTIVES: During the long-term follow-up of chronic hepatitis C patients treated with interferon alpha-2b, we have identified some patients who had continuous normalization, or transient elevation of the serum alanine aminotransferase levels within the first 6 months of follow-up and subsequent normalization, but HCV RNA was still found to be positive during the follow-up period (incomplete responder; ICR). We wished to clarify the characteristics of these patients, and to investigate the factors predictive of the response to interferon. METHODS: Seventy patients were treated with 6 MU of rIFN alpha-2b, three times weekly for 24 wk. Sixty-six patients (94%) completed the entire therapy and 2-yr follow-up protocol. RESULTS: Twenty-four months after cessation of IFN treatment, 24 patients (36%) were defined as complete responders (CR; continuously normal alanine aminotransferase levels, and HCV RNA negative). Nine patients (14%) were defined as ICR. Thirty-three patients (50%) were defined as nonresponders (NR). Compared with the CR or NR groups, the patients in the ICR group tended to have the mildest histological severity and lowest histological activity index scores, but there were no significant differences in any of the other histological features. The complete response rate was significantly higher in patients with low concentration of HCV RNA, and genotypes other than type II. CONCLUSIONS: After long-term follow-up of the 66 patients, 24 patients (36%) were CR, nine (14%) were ICR, and 33 (50%) were NR. The histological stage and indices of chronic hepatitis may help to predict a patient's response to IFN therapy.

Adult↗

Changes in immunoreactive insulin, C-peptide immunoreactivity, and immunoreactive glucagon in acute viral hepatitis.

Insulin and glucagon are thought to play important roles as hepatotrophic factors in acute viral hepatitis (AVH); however, few reports have investigated the responses and relationships of each of these hormones to liver damage in detail. We studied insulin and glucagon responses during the acute and recovery phases of AVH. We performed a glucose tolerance test (GTT) and an insulin sensitivity test (IST) in each phase in 11 patients with AVH. In 8 additional patients in the acute phase (total n = 19), were compared immunoreactive insulin (IRI) and C-peptide immunoreactivity (CPR) levels with transaminase levels. In the acute phase, IRI concentrations were normal from fasting to 60 min, despite an increased CPR level. In the recovery phase, IRI and CPR levels increased significantly. Immunoreactive glucagon levels in both phases did not differ significantly from those in controls. During the IST, the insulin sensitivity index in both phases was significantly lower than that in the controls. Fasting IRI and sigma IRI showed significant negative correlations with transaminase levels. We found enhanced insulin secretion and a decrease in plasma insulin in the acute phase of AVH. The discrepancy between IRI and CPR responses in the acute phase suggests an increase in the degradation or consumption of insulin in the liver.

Acute Disease↗

Separation and characterization of 25-hydroxyvitamin D3 3-sulfate in human plasma by high-performance liquid chromatography.

The separation and characterization of 25-hydroxyvitamin D3 3-sulfate in human plasma are carried out by high-performance liquid chromatography. The vitamin D sulfate fraction is obtained from a plasma specimen (three volunteers) by the combined use of a Sep-Pak C18 cartridge, for solid-phase extraction, and a lipophilic gel (piperidinohydroxypropyl Sephadex LH-20), for ion-exchange chromatography. 25-Hydroxyvitamin D3 3-sulfate is identified in the examined three specimens in two ways: its chromatographic behavior and that of its fluorescent labeled derivative using 4-[4-(6-methoxy-2-benzoxazolyl)phenyl]-1,2,4-triazoline-3,5- dione; and data obtained from the solvolysis reaction.

Calcifediol↗

Interaction of the cell-binding domain of fibronectin with VLA-5 integrin induces monokine production in cultured human monocytes.

The effect of fibronectin on IL-1 alpha, IL-1 beta, tumour necrosis factor-alpha (TNF-alpha), and IL-6 production was investigated with cultured monocytes isolated from human peripheral blood. Monokine concentrations were determined by both ELISA and bioassay. Fibronectin markedly stimulated the secretion of IL-1 alpha, IL-1 beta, TNF-alpha and IL-6 from cultured monocytes in a dose-dependent manner, with the maximal effect apparent within 24 h. Northern blot analysis revealed a marked increase in the abundance of mRNA specific for each monokine on exposure of monocytes to fibronectin. Monoclonal antibodies to the alpha chain of very late antigen (VLA)-5, the beta 1 integrin, the alpha chain of Mac-1, and the beta 2 integrin, as well as the synthetic peptide of GRGDSP (which corresponds to the cell-binding domain of fibronectin), inhibited (> 50%) fibronectin-induced monokine production. Monoclonal antibodies to the alpha chain of VLA-4, and the alpha chain of LFA-1, as well as the synthetic peptide CS-1 (which corresponds to the alternatively spliced connecting segment of fibronectin) and the control peptide GRADSP, had no inhibitory effect on monokine production. A MoAb, R60, that recognizes an epitope of the fibronectin molecule that includes the RGD sequence, inhibited monokine production, whereas the MoAb Y16, which recognizes another epitope of fibronectin not including RGD, did not. These results indicate that fibronectin-induced production of IL-1 alpha, IL-1 beta, TNF-alpha and IL-6 from cultured monocytes is mediated predominantly by interaction of the cell-binding domain of fibronectin with VLA-5, although Mac-1 also may contribute to this effect of fibronectin. Our results indicate that the interaction of fibronectin with integrins may contribute to the cytokine network in inflammatory response.

Binding Sites↗