Biomedical subjects

M Kasahara

Publications and source records attributed to M Kasahara.

At least 73 records · Page 4Linked to original sources

PubMed2000

Studies on the cytochrome P450 (CYP)-mediated metabolic properties of miocamycin: evaluation of the possibility of a metabolic intermediate complex formation with CYP, and identification of the human CYP isoforms.

Some macrolide antibiotics cause clinical drug interactions, resulting in altered metabolism of concomitantly administered drugs, via the formation of a metabolic intermediate (MI) complex with cytochrome P450 (CYP), or competitive inhibition of CYP. In this study, the possibility of MI complex formation by miocamycin (MOM) was assessed first. CYP contents and activities in rat liver microsomes were not affected and there were no detectable MI complexes after administration of MOM for either 3 or 10 days to rats. Furthermore, MOM did not form MI complexes in vitro even with microsomes from humans or dexamethasone-pretreated rats. Second, in vitro studies were conducted to identify the human CYP isoforms involved in four 14-hydroxylation reactions in the MOM metabolic pathway. The results showed that it was most likely CYP3A4 involved in the hydroxylations: 1) each hydroxylation in human liver microsomes from 10 different donors strongly correlated with testosterone 6 beta-hydroxylation; 2) each hydroxylation was essentially inhibited by ketoconazole and troleandomycin; 3) only cDNA-expressed CYP3A4 and CYP3A5 catalyzed the hydroxylations, and the activities of CYP3A5 were below 5% of those of CYP3A4; and 4) the apparent K(M) values obtained with native human liver microsomes were comparable with those obtained with cDNA-expressed CYP3A4. In conclusion, MOM is not an inhibitor of CYP via the formation of an MI complex. Moreover, CYP3A4 is mainly responsible for catalyzing the hydroxylation of MOM metabolites. Because CYP3A4 is the most abundant form of CYP in the liver and intestine, this isoform probably accounts for the majority of drug-MOM interactions observed in clinical practice.

Aniline Hydroxylase↗

PubMed2000

[Anesthetic management of the elderly patients with femoral neck fracture by sevoflurane and femoral nerve block].

Fracture of the femoral neck (FNF) is a significant cause of morbidity and mortality in the elderly, and the elderly with FNF are often high-risk patients for anesthesia. We studied 15 patients above 80 years of age with severe physical status (ASA III-IV). After femoral nerve block (for the pain of fracture) and lateral femoral cutaneous nerve block (for the cutting pain), surgical procedure was performed under general anesthesia by laryngeal mask airway under spontaneous ventilation. After the operation, morphine 2 mg was administered subcutaneously. In our experience, the majority of 15 patients cardiovascular status of remained stable, except one patient who needed ephedrine for hypotension and another patient who needed diclofenac sodium for post-operative pain relief.

Aged↗

PubMed2000

Thymidylate synthase expression correlates closely with E2F1 expression in colon cancer.

Thymidylate synthase (TS) is thought to be one of the target genes that the E2F1 transcription factor binds to and regulates. However, the relationship between the expressions of TS and E2F1 in primary colon cancer specimens remains unclear. The aim of this study was to define the relation of TS and E2F1 gene expressions in tumor samples from 23 colon cancer patients. TS and E2F1 gene expressions were measured by TaqMan reverse transcription-PCR assay using glyceraldehyde-3-phosphate dehydrogenase (GAPDH) as an internal standard and expressed as a TS:GAPDH or E2F1:GAPDH mRNA ratio. A close relationship was found between TS gene expression and E2F1 gene expression (r2 = 0.598, P < 0.001) in 23 tumor samples analyzed. Surprisingly, a high correlation between TS gene expression and E2F1 gene expression was observed even in advanced tumors from stage IV colon cancer patients. These results suggest that transcription of the TS gene may be regulated by E2F1 in primary colon cancer specimens and that this gene-regulatory pathway from E2F1 to TS may be highly conserved during malignant progression. Four of the 23 patients showed TS overexpression with increased E2F1 expression. These results suggest that the ability of a tumor to increase TS expression may possibly be due to an overexpression of E2F1. Although the number of patients was relatively small, our study provides new insights into the molecular mechanisms underlying the regulation of TS expression in colon cancers.

Adult↗

PubMed1999

Growth retardation in mice lacking the proteasome activator PA28gamma.

The proteasome activator PA28 binds to both ends of the central catalytic machine, known as the 20 S proteasome, in opposite orientations to form the enzymatically active proteasome. The PA28 family is composed of three members designated alpha, beta, and gamma; PA28alpha and PA28beta form the heteropolymer mainly located in the cytoplasm, whereas PA28gamma forms a homopolymer that predominantly occurs in the nucleus. Available evidence indicates that the heteropolymer of PA28alpha and PA28beta is involved in the processing of intracellular antigens, but the function of PA28gamma remains elusive. To investigate the role of PA28gamma in vivo, we generated mice deficient in the PA28gamma gene. The PA28gamma-deficient mice were born without appreciable abnormalities in all tissues examined, but their growth after birth was retarded compared with that of PA28gamma(+/-) or PA28gamma(+/+) mice. We also investigated the effects of the PA28gamma deficiency using cultured embryonic fibroblasts; cells lacking PA28gamma were larger and displayed a lower saturation density than their wild-type counterparts. Neither the expression of PA28alpha/beta nor the subcellular localization of PA28alpha was affected in PA28gamma(-/-) cells. These results indicate that PA28gamma functions as a regulator of cell proliferation and body growth in mice and suggest that neither PA28alpha nor PA28beta compensates for the PA28gamma deficiency.

Animals↗

PubMed1999

Two ancient allelic lineages at the single classical class I locus in the Xenopus MHC.

Unlike all other vertebrates examined to date, there is only one detectable class I locus in the Xenopus MHC. On the bases of a nearly ubiquitous and high tissue expression, extensive polymorphism, and MHC linkage, this gene is of the classical or class Ia type. Sequencing analysis of class Ia cDNAs encoded by eight defined MHC haplotypes reveals two very old allelic lineages that perhaps emerged when humans and mice diverged from a common ancestor up to 100 million years ago. The unprecedented age of these lineages suggests that different class Ia genes from ancestors of the laboratory model Xenopus laevis are now expressed as alleles in this species. The lineages are best defined by their cytoplasmic and alpha2 peptide-binding domains, and there are highly diverse alleles (defined by the alpha1 peptide-binding domain) in each lineage. Surprisingly, the alpha3 domains are homogenized in both lineages, suggesting that interallelic gene conversion/recombination maintains the high sequence similarity.

Alleles↗

PubMed1999

Activation of a cyanobacterial adenylate cyclase, CyaC, by autophosphorylation and a subsequent phosphotransfer reaction.

The CyaC protein, a cyanobacterial adenylate cyclase, has a unique primary structure composed of the catalytic domain of adenylate cyclase and the conserved domains of bacterial two-component regulatory systems, one transmitter domain and two receiver domains. In the present work, CyaC was produced in Escherichia coli as a histidine-tagged recombinant protein and purified to homogeneity. CyaC showed ability to autophosphorylate in vitro with the gamma-phosphate of [gamma-32P]ATP. CyaC derivatives were constructed by site-directed mutagenesis in which the highly conserved phosphorylation sites in the transmitter domain (His572) and receiver domains (Asp60 or Asp895) were replaced by glutamine and alanine residues, respectively. After autophosphorylation of the CyaC derivatives, the chemical stabilities of the phosphoryl groups bound to the derivatives were determined. It was found that His572 is the initial phosphorylation site and that the phosphoryl group once bound to His572 is transferred to Asp895. The enzyme activities of the CyaC derivatives defective in His572 or Asp895 were considerably reduced. Asp895 is phosphorylated by acetyl [32P]phosphate, a small phosphoryl molecule, but Asp60 is not. Acetyl phosphate stimulates adenylate cyclase activity only when Asp895 is intact. These results suggest that the phosphorylation of Asp895 is essential for the activation of adenylate cyclase and that Asp60 functions differently from Asp895 in regulating the enzyme activity.

Adenylyl Cyclases↗

PubMed1999

Long-term outcome of living related liver transplantation for patients with intrapulmonary shunting and strategy for complications.

BACKGROUND: In 320 living related liver transplantation performed between June 1990 and September 1997, there were 21 living related liver transplantation for patients with intrapulmonary shunting, manifested by digital clubbing, cyanosis, and dyspnea. We report the long-term outcome for more 6 months and our strategy to overcome complications in these recipients. PATIENTS: A total of 21 patients (age range 2-33 years, 19 children and 2 adults, 6 males and 15 females) were classified into three grades according to shunt ratio calculated by TcMAA pulmonary scintigraphy; 5 in mild group (shunt ratio: less than 20%), 6 in moderated group (20%-40%), and 10 in severe group (more than 40%). The original underlying liver disease was biliary atresia in all patients. RESULTS: Spearmen's correlation coefficient rank test revealed that shunt ratio correlated significantly with PaO2 in room air (P=0.0001), PaO2 in 100% oxygen (P=0.0004), hematocrit (P=0.0276), and period of dyspnea before transplantation (P=0.023). COMPLICATIONS: Wound infection occurred in 80, 66, and 80%, and bile leakage in 20, 0, 40% in mild, moderate, and severe group, respectively. Patients who had portal vein thrombosis, and intracranial complication were classified as severe group and the incidence was 20 and 20%, respectively. The patient actuarial one year survival was 80, 66.7, and 48%, in mild, moderate, and severe group, respectively, although there was no significant difference. All patients who survived improved hepatopulmonary syndrome and the length of period required for the resolution was significantly correlated to the preoperative shunt ratio (P=0.023). COMMENTS: Patients with severe shunting are susceptible to wound infection and bile leak. The trend of higher incidence of portal thrombosis and intracranial complications in the severe group was closely related high hematocrit. Secure surgical technique to reduce bile leak and delayed primary wound closure to reduce wound infection were found to be effective. Anticoagulant therapy by infusing heparin through the portal vein followed by coumadin could prevent fatal portal vein thrombosis without counter risk of fatal cerebral hemorrhage.

Adolescent↗

PubMed1999

Postoperative flow cytometry crossmatch in living donor liver transplantation: clinical significance of humoral immunity in acute rejection.

BACKGROUND: The role of humoral immunity in acute rejection in solid organ transplantation remains controversial, although it is known that the presence of antidonor antibodies may precipitate graft rejection. We investigated the clinical relevance of antidonor humoral immunity for living donor liver transplantation (LDLT) by means of flow cytometry crossmatch (FCXM). METHODS: T cell FCXM using fresh donor peripheral lymphocytes was performed before and up to 1 month after LDLT in 58 patients. Ten patients received ABO-incompatible grafts. IgM and IgG antidonor antibodies were analyzed in relation to clinical acute rejection as defined by liver function tests with or without histological evidence. RESULTS: Pretransplantation FCXM was positive for five patients (8.6%), resulting in two cases of positive posttransplantation FCXM and two rejection episodes. Twelve patients (20.7%) showed positive posttransplantation FCXM. The incidence of acute rejection within 1 month was 100% in FCXM-positive patients and 17.4% in FCXM-negative patients (P<0.001). Thirteen (76.5%) of 17 rejection episodes in ABO-compatible cases were associated with concomitant antidonor IgM antibody. IgG antibody was also identified in six of these episodes. Antidonor antibodies disappeared after rejection treatments in all cases, but with some delay in clinical improvement. On the other hand, no antidonor antibodies were detected in any of the four rejection episodes in ABO-incompatible cases. CONCLUSIONS: Early acute rejection in LDLT is significantly associated with antidonor T cell antibody formation in ABO-compatible cases. This suggests a definite role for donor-specific humoral immunity in acute rejection. Rejection episodes without antidonor antibodies may suggest graft injury by pure cellular immunity, or possibly the presence of humoral immunity triggered by antigens not present on donor T cells.

ABO Blood-Group System↗

PubMed1999

Impact of graft size mismatching on graft prognosis in liver transplantation from living donors.

BACKGROUND: Although living donor liver transplantation for small pediatric patients is increasingly accepted, its expansion to older/larger patients is still in question because of the lack of sufficient information on the impact of graft size mismatching. METHODS: A total of 276 cases of living donor liver transplantation, excluding ABO-incompatible, auxiliary, or secondary transplants, were reviewed from graft size matching. Forty-three cases were highly urgent cases receiving intensive care preoperatively. Cases were categorized into five groups by graft-to-recipient weight ratio (GRWR): extra-small-for-size (XS; GRWR<0.8%, 17 elective and 4 urgent cases), small (S; 0.8< or =GRWR< 1.0%, 21 and 7), medium (M; 1.0< or =GRWR<3.0%, 119 and 19), large (L; 3.0< or =GRWR<5.0%, 67 and 10), and extra-large (XL; GRWR> or =5.0%, 9 and 3). RESULTS: Smaller-for-size grafts were associated not only with larger and older recipients, but also with rather older donors. Posttransplant bilirubin clearance was delayed and aspartate aminotransferase corrected by relative graft size was higher in XS and S. Posttransplant hemorrhage and intestinal perforation were more frequent in XS and S, and vascular complications and acute rejection were more frequent in larger-for-size grafts. Consequently, graft survival in XS (cumulative 58% and actuarial 42% at 1 year) and S (76% and 74%) was significantly lower compared with that in M (93% and 92%) in elective cases. Graft survival in L (83% and 82%) and XL (75% and 71%) did not reach statistical significance. CONCLUSIONS: The use of small-for-size grafts (less than 1% of recipient body weight) leads to lower graft survival, probably through enhanced parenchymal cell injury and reduced metabolic and synthetic capacity. Although large-for-size grafts are associated with some anatomical and immunological disadvantages, the negative impact is less pronounced.

Actuarial Analysis↗

PubMed1999

Genome dynamics of the major histocompatibility complex: insights from genome paralogy.

It has recently become apparent that the human genome contains at least three regions that are paralogous to the major histocompatibility complex (MHC). The number of gene families with copies in the MHC and these paralogous regions is increasing steadily as genome analysis progresses. This review presents the updated listing of the human gene families that constitute the MHC paralogous group. When genes with multiple copies within the MHC, such as class I and class II genes, are counted as single entities, nearly one-third of the genes residing in the HLA complex have paralogous copies in at least one of the three paralogous regions. The review also discusses the long-term genome dynamics of the MHC, taking into account the rapidly accumulating information on the genomic organizations of the MHCs in various model organisms.

Animals↗

PubMed1999

Gastric cancer in young patients.

BACKGROUND: Delayed diagnosis, a high rate of histologically undifferentiated types of tumors, and rapid disease progression are frequently cited as the main reasons for the poor prognosis of gastric cancer in young patients. An improved prognosis has been anticipated for young gastric cancer patients because of recent improvements in digestive tract diagnostic techniques. This retrospective study was designed to determine whether these trends have had an impact on young Japanese patients with gastric cancer, and to further elucidate differences in clinicopathologic features between elderly and young patients. METHODS: From 1984 to 1995, 1654 patients with gastric cancer were admitted to our hospital. Of these, 86 patients (5.2%) were less than 40 years of age (young group). The clinicopathologic features of this young group were reviewed retrospectively, using hospital records, and compared with those of older patients (n = 499 [29.4%], 60 to 69 years of age). RESULTS: The young group contained significantly higher percentages of female patients, epigastric pain symptoms, depressed superficial type lesions, mucosal invasion, and poorly differentiated histology; percentages of hepatic metastasis and venous invasion were lower. Survival rates for all patients and for the resected cases were significantly better in the young group (p = 0.035 and 0.017 respectively). The percentage of early stage stomach cancers for the group less than 40 years of age was 49.0% in 1984-89, but had risen to 60.9% by 1990-95. CONCLUSIONS: Early diagnosis has improved the prognosis of young gastric cancer patients. Furthermore, these data show a recent shift in stage distribution; additional prognostic improvement is anticipated for young patients with early gastric cancer.

Adult↗

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

Closely linked polymorphic markers for determining the autosomal dominant allele (Cy) in rat polycystic kidney disease.

The Han:SPRD strain is an SD-background strain known to be a model of polycystic kidney disease (PKD) expressed through an autosomal dominant gene (Cy). However, different genotypes of this strain cannot be identified in the neonatal period. First, to establish an accurate method of determining the genotypes (Cy/Cy, Cy/+, +/+) which cause different disease progressions, we used polymorphic markers on rat chromosome 5. PCR products of tissue DNA templated with D5Rat9 showed distinct patterns on electrophoresis indicating three genotypes. Second, to determine whether the same locus plays a major role in expressing PKD, we performed linkage analyses in a [BN x (BN x Han:SPRD)F1] backcross. Cy/Cy and Cy/+ also caused PKD in a BN background. In this backcross, we discovered that D5Rat11 is located closer to the Cy locus than D5Mgh10, which is regarded as one of the closest loci. We conclude that D5Rat9 and D5Rat11 are useful markers for determining the presence of the Cy allele, which is regarded as the gene responsible for PKD.

Alleles↗

PubMed1999

Living related liver transplantation from heterozygote genetic carriers to children with Wilson's disease.

We reviewed the outcome of children undergoing living related liver transplantation (LRLT) for Wilson's disease (WD), and specifically addressed the potential risk associated with the use of donors who were heterozygous for the Wilson genetic defect. LRLTs were carried out in 11 children with WD, nine of whom presented with fulminant hepatic failure and two with end-stage hepatic insufficiency. The age of the patients ranged from 6 to 16 yr. Eight patients had hepatic encephalopathy and were plasmapheresed preoperatively. The donors (all parents: six fathers and five mothers) were all one-haplotype matched with their respective recipients, and were all therefore heterozygote carriers of the WD genetic defect. The serum ceruloplasmin levels were within normal limits in all donors (mean: 20.0 +/- 2.85 mg/dL). All recipients but one had low serum ceruloplasmin levels with a mean value of 11.6 +/- 7.36 mg/dL before transplantation. The serum ceruloplasmin levels had increased to an average of 21.0 +/- 3.76 mg/dL after LRLT at the latest evaluation, which ranged between 7 and 75 months after transplantation. A marked reduction in urinary copper excretion was observed in all recipients after transplantation. Of eight recipients presenting preoperatively with Kayser-Fleischer (K-F) rings, this abnormality resolved completely after LRLT in five patients and partially in three. All recipients are alive and remain well, and none have developed signs of recurrent WD after a mean follow-up period of 31 months (range 7-75 months). In conclusion, LRLT is an excellent choice for effective treatment of WD, and grafts chosen from heterozygote carriers of the condition do not appear to confer any risk of recurrence in the recipients.

Adolescent↗

PubMed1999

Existence of human DAZLA protein in the cytoplasm of human oocytes.

The human deleted in azoospermia-like autosomal (DAZLA) gene is thought to be a candidate gene for azoospermia. cDNA encoding the C-terminal 94 amino acid residues of human DAZLA was used to express a bacterial fusion protein which was then used to raise polyclonal antibodies in rabbits. Immunohistochemical analyses with the human DAZLA antiserum showed that the DAZLA protein is expressed at a cytoplasmic location in female germ cells. Available evidence suggests that the DAZLA gene is a participant in human oogenesis.

Adolescent↗

PubMed1999

The chromosomal duplication model of the major histocompatibility complex.

The major histocompatibility complex (MHC) is a genetic region that has been extensively studied by immunologists, molecular biologists, and evolutionary biologists. Nevertheless, our knowledge of how the MHC acquired its present-day organization is quite limited. The recent discovery that the mammalian genome contains regions paralogous to the MHC has led us to the proposal that the MHC region of jawed vertebrates arose as a result of ancient chromosomal duplications. Here, I review the current status of this proposal.

Animals↗

PubMed1999

In situ localization of S-phase-specific histone (H3) mRNA in Bowen's disease.

PCNA and Ki-67 immunohistochemistry has been used to assess cell proliferation in place of tritiated thymidine or BrdU labeling of S-phase cells. Recently, it has been possible to reliably demonstrate histone H3 mRNA by in situ hybridization in formalin-fixed and paraffin-embedded tissue sections. We have compared this new proliferation marker with Ki-67 and PCNA with regard to distribution of positive cells and labeling indices (LI%) for 22 cases of Bowen's disease. In normal skin, Ki-67-IHC positive cells and histone mRNA positive cells were observed in the basal and suprabasal layers of the epidermis. In Bowen's disease, positive cells with each marker were more frequent in upper neoplastic epidermis than in suprabasal layers, and the average LI%s were markedly elevated with all markers, the scores decreasing in the following order: PCNA-IHC, Ki-67-IHC and H3mRNA-ISH. However, the results of double staining demonstrated that S-phase cells do not necessarily show exactly the same distributions as with PCNA and Ki-67-IHC labeling. H3mRNA-ISH showed three different degrees of reaction with significantly different LI%s, whereas PCNA and Ki-67 LI% did not vary essentially in the same areas. These results strongly suggest that Bowen's disease, which is well known as a low-grade neoplastic state with malignant potential, also demonstrates clear intratumoral heterogeneity of S-phase cells using the H3mRNA-ISH method.

Adult↗

PubMed1999

Functional analysis of aquaporin-2 mutants associated with nephrogenic diabetes insipidus by yeast expression.

Mutations of aquaporin-2 (AQP2) vasopressin water channel cause nephrogenic diabetes insipidus (NDI). It has been suggested that impaired routing of AQP2 mutants to the plasma membrane causes the disease; however, no determinations have been made of mutation-induced alterations of AQP2 channel water permeability. To address this issue, a series of AQP2 mutants were expressed in yeast, and the osmotic water permeability (P(f)) of the isolated vesicles was measured. Wild-type and mutant AQP2 were expressed equally well in vesicles. P(f) of the vesicles containing wild-type AQP2 was 22 times greater than that of the control, which was sensitive to mercury and weakly dependent on the temperature. P(f) measurements and mercury inhibition examinations suggested that mutants L22V and P262L are fully functional, whereas mutants N68S, R187C, and S216P are partially functional. In contrast, mutants N123D, T125M, T126M, A147T, and C181W had very low water permeability. Our results suggest that the structure between the third and fifth hydrophilic loops is critical for the functional integrity of the AQP2 water channel and that disruption of AQP2 water permeability by mutations may cause NDI.

Animals↗