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Biomedical subjects

M Kubota

Publications and source records attributed to M Kubota.

At least 127 records · Page 7Linked to original sources
PubMed1999

Contribution of hydrogen bonds to the conformational stability of human lysozyme: calorimetry and X-ray analysis of six Ser --> Ala mutants.

To further examine the contribution of hydrogen bonds to the conformational stability of the human lysozyme, six Ser to Ala mutants were constructed. The thermodynamic parameters for denaturation of these six Ser mutant proteins were investigated by differential scanning calorimetry (DSC), and the crystal structures were determined by X-ray analysis. The denaturation Gibbs energy (DeltaG) of the Ser mutant proteins was changed from 2.0 to -5.7 kJ/mol, compared to that of the wild-type protein. With an analysis in which some factors that affected the stability due to mutation were considered, the contribution of hydrogen bonds to the stability (Delta DeltaGHB) was extracted on the basis of the structures of the mutant proteins. The results showed that hydrogen bonds between protein atoms and between a protein atom and a water bound with the protein molecule favorably contribute to the protein stability. The net contribution of one intramolecular hydrogen bond to protein stability (DeltaGHB) was 8.9 +/- 2.6 kJ/mol on average. However, the contribution to the protein stability of hydrogen bonds between a protein atom and a bound water molecule was smaller than that for a bond between protein atoms.

Alanine↗
PubMed1999

Application of a newly developed, highly sensitive camera and a 3-dimensional high-definition television system in experimental ophthalmic surgeries.

OBJECTIVE: To apply a new television system, which displays highly sensitive, high-quality 3-dimensional (3-D) images, in performing experimental ophthalmic surgeries. METHODS: By combining a high-gain avalanche rushing-amorphous photoconductor (HARP) camera, recently developed in Japan, which has 600 times greater sensitivity than conventional television cameras, and a single-camera, 3-D high-definition television system, which displays high-quality 3-D images, we performed cataract/intraocular lens surgeries and pars plana vitrectomies under various illumination intensities in pig cadaver eyes. RESULTS: Cataract/intraocular lens surgeries were performed using 7.3% the intensity of ordinary surgical microscopic illumination; vitrectomies were performed using 30.2% the intensity of an ordinary endoillumination probe with the HARP camera and by observing the stereoscopic display of the single-camera 3-D high-definition television system. Images identical to those observed by the surgeon were displayed on the stereoscopic display monitor. CONCLUSION: The system not only allowed surgeries to be performed under lower intensities of operating light but also provided real-time, highly sensitive 3-D images identical to those observed by the surgeon; thus, the device may be effectively used for education, team surgery, and telesurgery. CLINICAL RELEVANCE: The new television system for ocular surgeries to be performed under lower intensities of operating light as well as providing real-time, highly sensitive 3-D images identical to those observed by the surgeon may be effectively used for education and telesurgery.

Animals↗
PubMed1999

Acute pure red cell aplasia associated with allopurinol therapy.

Several investigators have reported patients with acute pure red cell aplasia (PRCA) caused by anticonvulsants, antibiotics, or antithyroid agents. Allopurinol is known to be a causative agent of aplastic anemia, but there have been few reports of acute PRCA induced by allopurinol. We describe here a 15-year-old boy who suffered from anemia 6 weeks after initiation of allopurinol therapy; his anemia immediately improved after cessation of the drug. His bone marrow showed severe erythroid hypoplasia with a myeloid/erythroid ratio of 18.6 and low expression of glycophorin A detected on cell-surface antigen analysis. No morphological abnormalities were observed in myeloid series and megakaryocytes. The prolonged plasma iron disappearance rate and the decreased plasma iron turnover rate also indicated erythroid hypoplasia. He had been free from any infections, including parvovirus B19, before manifestation of PRCA. Taken together, these results suggest a diagnosis of acute PRCA. This side effect of allopurinol should be taken into consideration.

Acidosis↗
PubMed1999

Detection of a novel DNA virus (TTV) sequence in peripheral blood mononuclear cells.

DNA sequences of a novel DNA virus (TTV) were examined in 81 peripheral blood mononuclear cell (PBMC) DNA samples from 48 children and 33 adults, 22 cord blood mononuclear cells (CBMC) DNA samples, and 7 autopsy liver tissue DNA samples by a hemi-nested polymerase chain reaction (PCR). The PCR was carried out using the published primers (NG059, NG061, NG063) to amplify TTV DNA sequences. The sequences were detected in 4 of 81 (5%) PBMC DNA samples, in none of 22 (0%) CBMC DNA samples, and in 2 of 7 (29%) liver tissue DNA samples by direct gel analysis. The PCR-amplified products were confirmed by direct sequencing. The sequencing showed considerable diversities, with differences of 0-55% in 6 TTV isolates, compared with the prototype sequence of TTV. These results suggest that TTV is a ubiquitous virus that produces asymptomatic infection in a large proportion of the general population without transfusion of blood-derived products. To our knowledge, this is the first report describing the detection of TTV DNA sequences in PBMCs.

Adult↗
PubMed1999

Preoperative portal vein embolization: an audit of 84 patients.

Preoperative portal vein embolization (PVE) was performed in 84 patients before extensive liver resection for various diseases. By the criteria of liver volumetric determination, some patients were candidates for PVE, whereas others were not, even though the same surgical procedure, such as extended right lobectomy (ERL), was scheduled. PVE using gelatin sponge powder induced hypertrophy in the nonembolized lobe (0%-171%; median, 30%) and proportional atrophy in the embolized lobe in 2 weeks without eliciting any major inflammatory or necrotic reaction, as evidenced histologically and by the minimal elevations in the serum aspartate transaminase (AST) and alanine transaminase (ALT) values. Alterations in the total bilirubin level and prothrombin time were also insignificant and transient, indicating that hepatocyte functions were not impaired by PVE. Not all patients who undergo PVE proceed with the scheduled hepatic resection procedure, so it is a great advantage that gelatin sponge causes minimal damage compared with other embolizing materials such as cyanoacrylate and absolute ethanol, which have been reported to induce an inflammatory reaction or histological alteration. Our multiple regression analysis showed that three factors, diabetes mellitus, a high total bilirubin level at the time of PVE, and being male, each reduced the extent of hypertrophy in the nonembolized lobe (r2 =.30). By contrast, cholestasis appeared to accelerate the process of atrophy in the embolized lobe (r2 =.16). In conclusion, PVE by gelatin sponge powder is a safe and effective preoperative maneuver that induces hypertrophy of the section of the liver that will remain after partial hepatectomy.

Adult↗
PubMed1999

Seasonal changes in the freezing behavior of xylem ray parenchyma cells in four boreal hardwood species

The freezing behavior of xylem ray parenchyma cells in several boreal hardwood species, namely, Betula platyphylla, Populus canadensis, P. sieboldii, and Salix sachalinensis, was examined by differential thermal analysis (DTA), cryo-scanning electron microscopy (Cryo-SEM), and freeze-fracture replica electron microscopy. Although DTA profiles of samples harvested in summer and in winter suggested that the xylem ray parenchyma cells in all four species responded to freezing stress by extracellular freezing, Cryo-SEM showed clearly that the xylem ray parenchyma cells in all these species responded to freezing stress by shallow supercooling in summer and by extracellular freezing in winter. It is suggested that DTA failed to reveal the true freezing behavior of xylem ray parenchyma cells because of an overlap of temperature ranges between the high-temperature exotherm and the low-temperature exotherm and/or because of the limited extent of the LTE. The seasonal changes in freezing behavior of xylem ray parenchyma cells in all these boreal species, which are results of seasonal cold acclimation, support the hypothesis that a gradual shift of freezing behavior in xylem ray parenchyma cells from shallow supercooling in hardwood species that grow in tropical zones to extracellular freezing in hardwood species that grow in cold areas might be a result of the evolutionary adaptation of hardwood species to cold climates. Copyright 1999 Academic Press.

Journal Article↗
PubMed1999

One-step affinity purification of the G protein betagamma subunits from bovine brain using a histidine-tagged G protein alpha subunit.

An efficient one-step affinity purification of bovine brain G protein betagamma subunits (betagamma's) is described. The betagamma's, in a detergent extract of brain membranes, are first dissociated from the alpha subunits (alpha's), reassociated with decahistidine-tagged alphail produced in bacteria, and then adsorbed onto Ni2+-nitrilotriacetic acid-agarose via the histidine tag. This mild adsorption retained the high activity of the ligand alpha's, in contrast to the commonly used chemical crosslinking methods. A wash step with a buffer containing chaotropic ions (SCN-) completely removed contaminating proteins that were refractory to washes with high concentrations of detergents, after which the highly purified betagamma's were eluted with a buffer containing Al3+, Mg2+, and F- ions. The obtained betagamma's were found to be fully functional, as assessed by their ability to support pertussis toxin-catalyzed ADP-ribosylation of alphail. Since the combination of the mild adsorption via the histidine tag and the wash with chaotropic ions can be easily applied to purifying betagamma's from various animal tissues, this new chromatographic method is expected to facilitate the purification of other membrane proteins that bind to Galpha and/or Galphabetagamma.

Adsorption↗
PubMed1999

Helicobacter pylori infection in postoperative patients with biliary atresia. A benign colonization?

The prevalence of Helicobacter pylori infection in postoperative patients with biliary atresia (BA) was investigated in relation to esophageal varices, portal-hypertensive gastropathy (PHG), and peptic ulcer disease (PUD) in 25 Japanese patients (10 boys and 15 girls) aged from 16 months to 20 years. Gastric biopsy specimens obtained during endoscopy were used for both the rapid urease test and modified Giemsa staining. The patients were classified into three groups according to liver function: 15 in group A (total bilirubin [TB] < 1.0 mg/dl), 7 in group B (1.0 </= TB < 2.0 mg/dl), and 3 in group C (TB >/= 2.0 mg/dl). Esophageal varices were found in 19 patients (60% of group A and all patients in groups B and C) and PHG in 3 group B patients. However, no gastric or duodenal ulcers were found in any case. Only 2 patients (8%) had H. pylori colonization of the gastric mucosa. Both, however, belonged to group A, and the degree of chronic neutrophilic infiltration of the mucosal layer was as mild as that of the other patients. The prevalence of H. pylori infection and PUD in postoperative patients with BA was quite low, and a pathological relationship with the severity of liver disease could not be determined in these patients.

Biliary Atresia↗
PubMed1999

Identification of an autoimmune enteropathy-related 75-kilodalton antigen.

BACKGROUND & AIMS: We have previously reported a 75-kilodalton autoantigen specific to X-linked autoimmune enteropathy (AIE) associated with tubulonephropathy. The aim of this study was to identify the autoantigen. METHODS: Complementary DNA (cDNA) clones were isolated by immunoscreening a human duodenal cDNA-expression library with serum from a patient with AIE. RESULTS: cDNA encoding the 75-kilodalton antigen (AIE-75) was identified. The composite nucleotide sequence of the cDNA for AIE-75 was 2214 base pairs long and encoded 552 amino acids. The genomic sequence of AIE-75 was found in Sequence DataBank, which consisted of 21 exons and was located on the chromosome 11p14.3. Recombinant AIE-75 specifically reacted with sera from 3 of 4 unrelated patients with AIE but not with 58 control sera. AIE-75 was predominantly distributed in the epithelial cells of the luminal surface and the upper half of the crypts of the intestine and in the proximal renal tubulus. Similarity searches revealed that the AIE-75 cDNA sequence was an authentic form of several colon cancer-related cDNAs of unknown function. The deduced amino acid sequence contained 3 conserved PSD-95/Dlg/ZO-1 (PDZ) domains. CONCLUSIONS: AIE-75 is a PDZ domain-containing protein expressed in the differentiated epithelial cells of the intestine and kidney and may be involved in protein-protein interaction. The identification of the autoantigen may prove useful in the approach to the pathogenesis of this poorly understood disease.

Amino Acid Sequence↗
PubMed1999

Influence of age on the presentation and outcome of choledochal cyst.

PURPOSE: The aim of this study was to identify the most appropriate timing for surgery in newborns with choledochal cysts. METHODS: The clinical and histological data of 8 newborn cases of choledochal cysts (newborn group) were compared with 45 cases that were diagnosed later than the newborn period (late group). RESULTS: The mean and standard deviation of age at diagnosis was 0.4+/-0.4 months and 43.4+/-37.8 months in the newborn and late group, respectively. The age at operation was significantly earlier in the newborn group than in the late group (4.9+/-4.5 months v54.7+/-47.0 months). Although no significant difference in the time that elapsed between the operation and the onset of symptoms between the newborn and late groups (4.5+/-4.7 months v11.3+/-21.1 months), the serum bilirubin level (4.6+/-3.8 mg/dL v1.8+/-3.4 mg/dL) and the grade of liver fibrosis (2.0+/-0.8 v1.1+/-0.8) were significantly higher in the newborn group than in the late group. CONCLUSION: The newborn group should be considered as a special group of patients with different clinical course and pathology than those of the late group, which necessitate the early surgical intervention to prevent progression of liver fibrosis.

Age Factors↗
PubMed1999

Prognostic factors in surgical treatment of solitary brain metastasis after resection of non-small-cell lung cancer.

Patients with brain metastasis after resection of non-small-cell lung cancer usually have poor prognosis. A few such patients, however, survive for long periods after surgical resection of brain metastases. To evaluate the prognostic factors in resection of solitary brain metastasis from non-small-cell lung cancer, we reviewed 24 cases undergoing resection of solitary brain metastasis after resection of the primary site from 1977 to 1993. The patient population consisted of 20 men and four women ranging in age from 40 to 75 years old (average, 57.8 years old). None of the patients had systemic metastasis except in the brain at the time of brain surgery. The overall survival rates were 12.5% at 3 years and 8.3% at 5 years after brain surgery. The longest survival periods were 11.5 years after brain surgery and 15.4 years after lung surgery. The interval between lung and brain surgery (< or =360 days vs. >360 days), differentiation of primary cancer (poor vs. moderate), size of primary site (< or =5.0 cm vs. >5.0 cm), and operation of primary site (lobectomy vs. pneumonectomy) significantly affected survival as shown by univariate analysis (P<0.05). Other clinical factors (age, gender, histology, T- and N-status, 'resectability with curative intent' of the primary site, location of the brain metastasis and postoperative radiation therapy) did not affect survival. Multivariate analysis using Cox's proportional hazards model indicated that an interval of more than 360 days between the two surgical procedures (hazard ratio = 0.2351, P = 0.0136) and lobectomy (hazard ratio = 0.5274, P = 0.0416) were independent prognostic factors. In conclusion, patients with solitary brain metastasis from non-small-cell lung cancer without other organ metastasis, in whom relapse in the brain occurred more than 1 year after resection of the primary site and in whom lobectomy was performed, should be treated surgically to maximize the chance of prolonged survival.

Adenocarcinoma↗
PubMed1999

Tyrosine phosphorylation and association of BIT with SHP-2 induced by neurotrophins.

BIT (brain immunoglobulin-like molecule with tyrosine-based activation motifs) is a membrane glycoprotein that has two cytoplasmic TAMs (tyrosine-based activation motifs). We previously reported that tyrosine-phosphorylated TAMs of BIT interact with the Src homology 2 domain-containing protein tyrosine phosphatase SHP-2 both in vitro and in transfected cells, and this association results in a potent stimulation of the phosphatase activity of SHP-2. Both BIT and SHP-2 are highly expressed in the mammalian brain, and they may play important roles in the regulation of synaptic function. In this study, we found that nerve growth factor (NGF) treatment of PC12 cells leads to the tyrosine phosphorylation of BIT and a subsequent complex formation between BIT and SHP-2. Furthermore, brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) also induced the tyrosine phosphorylation of BIT and the association with SHP-2 in primary cultured rat neurons. Our results suggest that the BIT-SHP-2 signaling pathway is a novel signal transduction mechanism of neurons that acts in response to neurotrophic factors such as NGF, BDNF, and NT-3.

Animals↗
PubMed1999

Lung cancer in a child with a substantial family history of cancer.

The occurrence of primary lung cancer is rare in childhood. The case of an 11-year-old boy with primary lung cancer is presented in this report. He had a substantial family history of cancer. His chief complaint was coughing with right chest pain. A chest radiograph showed a coin lesion in the right lower lung. A right lower lobectomy revealed a squamous cell carcinoma (stage IIIA at Japanese TNM classification). Systemic chemotherapy using cisplatin, vindesine, THP-adriamycin and cyclophosphamide was performed. Six months after surgery, a recurrent tumor occurred. An analysis of the familial cancer related genes (p53 gene and mismatch repair gene) showed no abnormality.

Age of Onset↗
PubMed1999

Mucosal Th1- versus Th2-type responses for antibody- or cell-mediated immunity to simian immunodeficiency virus in rhesus macaques.

Simian immunodeficiency virus (SIV)-specific B cell responses and the Th1- or Th2-type profiles of cytokine expression were determined for rhesus macaques immunized with SIV antigens via the iliac lymph nodes (by use of a targeted lymph node [TLN] procedure) or orally with SIV p55gag plus cholera toxin (CT) as a mucosal adjuvant. Analysis of CD4+ T cells purified from SIV-stimulated peripheral blood mononuclear cells of immunized macaques revealed that Th2 cytokine production gradually increased after the second and third TLN immunization. Analysis of SIV-specific B cell responses revealed that peak SIV-specific IgA B cell responses followed the third TLN immunization and occurred during peak Th2-type T cell responses. Oral immunization of macaques with p55gag plus CT induced interferon-gamma-secreting Th1-type and select Th2-type cytokine-producing CD4+ T helper cells, which most likely accounted for the induction of p55-specific systemic IgG and mucosal IgA responses.

Animals↗
PubMed1999

Chemoprevention by curcumin during the promotion stage of tumorigenesis of mammary gland in rats irradiated with gamma-rays.

We have evaluated the chemopreventive effects of curcumin on diethylstilbestrol (DES)-induced tumor promotion of rat mammary glands initiated with radiation. Sixty-four pregnant rats received whole body irradiation with 2.6 Gy gamma-rays from a 60Co source at day 20 of pregnancy and were divided into two groups after weaning. In the control group of 39 rats fed a basal diet and then implanted with a DES pellet for 1 year, 33 (84.6%) developed mammary tumors. Twenty-five rats were fed diet containing 1% curcumin immediately after weaning and received a DES pellet, as for the control. The administration of dietary curcumin significantly reduced the incidence (28.0%) of mammary tumors. Multiplicity and Iball's index of mammary tumors were also decreased by curcumin. Rats fed the curcumin diet showed a reduced incidence of the development of both mammary adenocarcinoma and ER(+)PgR(+) tumors in comparison with the control group. On long-term treatment with curcumin, body weight and ovarian weight were reduced, but liver weight was increased. Compared with the control rats, the curcumin-fed rats showed a significant reduction in serum prolactin, whereas estradiol-17beta and progesterone concentrations were not significantly different between the two groups. Curcumin did not have any effect on the concentration of free cholesterol, cholesterol ester and triglyceride. Feeding of the curcumin diet caused a significant increase in the concentrations of tetrahydrocurcumin, arachidonic acid and eicosapentaenoic acid and a significant decrease in thiobarbituric acid-reactive substance concentration in serum. Whole mounts of the mammary glands showed that curcumin yielded morphologically indistinguishable proliferation and differentiation from the glands of the control rats. These findings suggest that curcumin has a potent preventive activity during the DES-dependent promotion stage of radiation-induced mammary tumorigenesis.

Animals↗
PubMed1999

A small breast cancer detected by PET.

A small breast cancer was detected by positron emission tomography (PET) in an asymptomatic individual. Physical examination, mammography and magnetic resonance imaging all failed to identify the tumor. Treatment was partial resection of the breast. Based on the resected specimen, the tumor was 6 mm in diameter. Although previous studies have shown PET to be highly sensitive for the detection of primary breast cancer, detectability of tumors smaller than 1 cm is uncertain. Our case suggests the potential utility of PET for the early detection of primary breast cancer.

Breast Neoplasms↗