Biomedical subjects

C Kobayashi

Publications and source records attributed to C Kobayashi.

At least 37 records · Page 2Linked to original sources

PubMed2001

[Determination of neohesperidin dihydrochalcone in foods].

An HPLC method was developed for the determination of neohesperidin dihydrochalcone (NHDC) in foods. A solid sample was extracted with methanol. The extract was evaporated and the residue was dissolved in methanol-water (2:8) mixture. In the case of fluid sample, the sample solution was prepared by dilution with methanol-water (2:8) mixture. The sample solution was cleaned up on a C18 cartridge. The cartridge was washed with water and methanol-water (3:7) mixture, and NHDC was eluted with methanol-water (7:3) mixture. NHDC in the eluate was separated on an ODS column and determined with a UV detector (282 nm). The identity of NHDC in foods was confirmed by means of HPLC with a photodiode-array detector. The recoveries of NHDC added to various kinds of foods were 75.2-134%. The determination limit of NHDC was 1 microgram/g.

Chalcone↗

PubMed2001

The influence of sex hormones on renal osteopontin expression and urinary constituents in experimental urolithiasis.

PURPOSE: To our knowledge the influence of sex hormones on urinary stone formation remains undetermined. We investigated the effect of castration on urinary lithogenic factors and renal osteopontin expression in rats previously treated with ethylene glycol. MATERIALS AND METHODS: Sprague-Dawley rats were divided normal males, castrated males, males with 2 weeks of 0.75% ethylene glycol treatment, castrated males with 2 weeks of 0.75% ethylene glycol treatment, normal females, castrated females, females with 2 weeks of 0.75% ethylene glycol treatment and castrated females with 2 weeks of 0.75% ethylene glycol treatment. We analyzed 24-hour urine samples for urinary constituents, such as calcium, oxalate, citrate, uric acid, phosphate, magnesium, sodium, potassium and creatinine. The kidneys were examined for osteopontin expression by Northern blot analysis and for crystal deposition by histological examination. RESULTS: In intact male rats calcium and citrate excretion decreased and oxalate excretion increased significantly after ethylene glycol treatment. Castrated male rats with ethylene glycol had greater calcium and less oxalate excretion than male intact rats with ethylene glycol. In intact female rats uric acid excretion decreased and only calcium excretion increased significantly after ethylene glycol treatment. Castrated female rats with ethylene glycol excreted significantly more oxalate and less calcium than intact female rats with ethylene glycol. Renal osteopontin expression was the same in male intact and castrated rats, and in female intact and castrated rats. In males with ethylene glycol expression was stronger in castrated than in intact rats. In females with ethylene glycol expression was weaker in castrated than in intact rats. No crystal deposits were found in the kidneys in any group. CONCLUSIONS: Testosterone appears to promote stone formation by suppressing osteopontin expression in the kidneys and increasing urinary oxalate excretion. Estrogen appears to inhibit stone formation by increasing osteopontin expression in the kidneys and decreasing urinary oxalate excretion.

Animals↗

PubMed2000

Adherence protects the binding sites of Helicobacter pylori urease from acid-induced damage.

Colonization by Helicobacter pylori partly depends on acid-dependent adherence by urease to gastric mucin. To further verify the relevance of urease adherence to colonization, the influence of acidity on the binding sites of H. pylori urease was investigated. When enzyme-based in vitro ligand capture assays were used, the effect of acidity on the binding site of H. pylori urease was determined against a backdrop medium consisting of acidic buffers simulating the luminal side of gastric mucus. A high degree of stability was exhibited by adherent urease, suggesting a pivotal role by the denatured enzyme in the persistence of the bacterium within the acidified compartment of gastric mucus.

Bacterial Adhesion↗

PubMed2000

Comparison of metabolic risk factors in patients with recurrent urolithiasis stratified according to age and gender.

OBJECTIVE: Little is known regarding the metabolic features associated with aging and gender in urolithiais patients. We compared the metabolic characteristics among 3 generations (young, middle-aged and old) with recurrent calcium-containing urinary stones. METHODS: One hundred and eighty-one patients with recurrent calcium-containing stones, including 71 patients aged </=45 years (group 1), 71 patients aged 46-60 years (group 2) and 39 patients aged >/=61 years (group 3), were investigated by metabolic evaluation. The frequencies of metabolic abnormalities, the value of each urinary constituent and the supersaturation index (AP(CaOx) index) were compared among subgroups of the 3 generations, containing both males and females. RESULTS: The number of metabolic abnormalities was the greatest in group 1, followed by group 2 and group 3. Hyperoxaluria was the most common abnormality in each group. Group 1 females showed a lower frequency of hypocitraturia than group 3 females. This was the only characteristic that showed a significant difference between the groups. Urinary calcium excretion was significantly greater in group 1 than in group 3. Urinary citrate excretion and the AP(CaOx) index were significantly higher in group 1 than in group 3 in females. Male patients had a significantly higher number of metabolic abnormalities than female patients, especially in group 1. CONCLUSION: Multiple metabolic abnormalities, particularly a high calcium excretion appear to be crucial factors in the development and recurrence of urolithiasis in young patients. Low urinary citrate excretion could play an important role in the occurrence of urolithiasis in elderly females.

Age Factors↗

PubMed2000

Degradation products generated by sonication of benzyl alcohol, a sample preparation solvent for the determination of residual solvents in pharmaceutical bulks, on capillary gas chromatography.

Benzyl alcohol used as the sample preparation solvent in the determination of residual solvents in pharmaceutical bulks yielded benzene, toluene, and benzaldehyde on capillary gas chromatography (GC) by sonication. The factors responsible for compounds generated are discussed. The quality of benzyl alcohol and the type of sonicator were not involved in the generation of benzene, toluene, and benzaldehyde, whereas matrix contributions were observed. The degradation profiles of benzyl alcohol and its analogous compounds obtained by pyrolysis-GC/mass spectrometric analysis were similar to those obtained by sonication, suggesting that benzyl alcohol is degraded by the high local heat generated by sonication. Consequently, no matter how long it may take to dissolve bulk substances in benzyl alcohol completely, we do not recommend the use of a sonicator in sample preparation for the determination of residual solvents in pharmaceutical bulks.

Benzyl Alcohols↗

PubMed2000

A tetrahydroisoquinoline-monoterpene glucoside and an iridoid glucoside from Alangium kurzii.

From the leaves of Alangium kurzii, a new tetrahydroisoquinoline-monoterpene glucoside, 6-O-methyl-N-deacetylipecosidic acid and a new iridoid glucoside, 10-O-benzoyladoxosidic acid, were isolated along with alangiside, demethylalangiside, 6''-O-beta-D-glucosylhenryoside, uridine and four known flavonoid glycosides. The structures of new glucosides were determined on the basis of spectroscopic and chemical methods.

Acetylation↗

PubMed2000

Toxoplasmic encephalitis in patients with acquired immunodeficiency syndrome--four case reports.

Four patients, all males aged 40-64 years, presented with toxoplasmic encephalitis associated with human immunodeficiency virus (HIV) infection manifesting as nonspecific neurological deficits such as epilepsy or hemiparesis. Magnetic resonance imaging showed single or multiple lesions with ring enhancement, mimicking metastatic brain tumor or brain abscess. Marked eosinophilia was noted in three patients. Two patients who received anti-toxoplasma chemotherapy in the early stage had a good outcome. However, the other two patients suffered rapid neurological deterioration and needed decompressive surgery, resulting in a poor outcome. Toxoplasma diffusely infects the whole central nervous system from the early stage. The outcome for patients who needed emergency surgery was poor. Therefore, this rare but increasingly common infectious disease must be considered in the differential diagnosis of a patient with neuroimaging findings similar to those of metastatic tumor or brain abscess. Appropriate chemotherapy should be started immediately after HIV-positive reaction is identified in patients with single or multiple mass lesions with ring enhancement.

AIDS Serodiagnosis↗

PubMed1999

Evolution of Dust Extinction and Supernova Cosmology.

We have made a quantitative calculation for the systematic evolution of the average extinction by interstellar dust in host galaxies of high-redshift Type Ia supernovae by using a realistic model of photometric and chemical evolution of galaxies and supernova rate histories in various galaxy types. We find that the average B-band extinction at z approximately 0.5 is typically 0.1-0.2 mag larger than the present value, under a natural assumption that dust optical depth is proportional to gas column density and gas metallicity. This systematic evolution causes average reddening with E(B-V&parr0; approximately 0.025-0.05 mag with the standard extinction curve, and this is comparable with the observational uncertainty of the reddening of high-redshift supernovae. Therefore, our result does not contradict the observations that show no significant reddening in high-z supernovae. However, the difference in apparent magnitude between an open universe and a Lambda-dominated flat universe is only approximately 0.2 mag at z approximately 0.5, and hence this systematic evolution of extinction should be taken into account in a reliable measurement of cosmological parameters. Considering this uncertainty, we show that it is difficult to discriminate between open and Lambda-dominated flat cosmologies from the current data.

Journal Article↗

PubMed1999

The process of pharynx regeneration in planarians.

To understand the cellular events during planarian regeneration, we analyzed the process of pharynx regeneration in both head and tail pieces using cell-type-specific markers. Interestingly, cells expressing the pharynx-muscle-specific myosin heavy chain gene (DjMHC-A) appeared within 24 h after amputation (prior to the formation of a pharynx rudiment) in the mesenchymal space of the stump, not in the blastema region. These DjMHC-A-positive cells migrated to the midline and formed the pharynx rudiment. Even after formation of the pharynx rudiment, DjMHC-A-positive cells constantly appeared in the mesenchymal space in the region surrounding the pharynx rudiment and participated in the growth of the pharynx rudiment. These observations clearly indicated that the cells involved in pharynx-muscle formation are committed in the mesenchymal space of the stump, rather than in the blastema region or the pharynx rudiment during planarian regeneration. We also analyzed the process of regeneration of the pharynx epithelia using a monoclonal antibody and investigated the origin of the pharynx epithelia.

Animals↗

PubMed1999

PCR random mutagenesis into Escherichia coli serine acetyltransferase: isolation of the mutant enzymes that cause overproduction of L-cysteine and L-cystine due to the desensitization to feedback inhibition.

PCR random mutagenesis in the cysE gene encoding Escherichia coli serine acetyltransferase was employed to isolate the mutant enzymes that, due to a much less feedback inhibition by L-cysteine, cause overproduction of L-cysteine and L-cystine in the recombinant strains. The L-cysteine auxotrophic and non-utilizing E. coli strain was transformed with plasmids having the altered cysE genes. Then, several transformants overproducing L-cysteine were selected by detecting the halo formation of the L-cysteine auxotroph. The production test of amino acids and analysis of the catalytic property on the mutant enzymes suggest that the carboxy-terminal region of serine acetyltransferase plays an important role in the desensitization to feedback inhibition and the high level production of L-cysteine and L-cystine.

Acetyltransferases↗

PubMed1999

Molecular cloning of cDNAs encoding hypoxia-inducible factor (HIF)-1alpha and -2alpha of bovine arterial endothelial cells.

Hypoxia-inducible factor (HIF)-1alpha and -2alpha are two basic helix-loop-helix/PAS domain transcriptional factors that mediate hypoxia-induced gene expression. We found that bovine arterial endothelial cells (BAEC) expressed both HIF-1alpha and -2alpha by RT-PCR and then isolated cDNAs encoding these two transcriptional factors of BAEC. The deduced amino acid sequences of both HIF-1alpha and -2alpha showed high homologies among mammalian species. Northern blot analysis indicated that the mRNAs for HIF-1alpha and -2alpha from BAEC showed a size of approx. 5.5 and 6.2 kilobases, respectively and that both mRNAs were constitutively expressed and not induced by hypoxia in BAEC.

Amino Acid Sequence↗

PubMed1999

Parasite infection and Japanese cedar pollinosis in monkeys.

To evaluate the relationship between helminthic parasite infection and sensitization to Japanese cedar (Cryptomeria japonica; CJ) pollen allergens in Japanese monkeys (Macaca fuscata), we examined the parasite infection, presence of anti-pollen allergen IgE and development of pollinosis. Serum samples and fecal specimens were taken from 169 monkeys in five troops, and the presence of IgE antibody for CJ pollen allergen and of helminthic parasite eggs in their feces was examined. Of the 169 monkeys, helminthic parasite eggs from 138 monkeys were detected. The frequency of anti-CJ IgE (19%) and the level of total IgE did not differ significantly between the monkeys with and without parasite eggs. We examined the presence of anti-CJ IgE and pollinosis symptoms in 31 monkeys of a troop; six of the monkeys demonstrated anti-CJ IgE and pollinosis symptoms. Five of these six monkeys had parasite eggs. We found that the monkeys that demonstrated anti-CJ IgE and pollinosis symptoms had helminthic parasite infections. These data suggest that helminthic parasite infection does not reduce the development of clinical signs of CJ pollinosis in Japanese monkeys.

Allergens↗

PubMed1999

Nuclear localization of hypoxia-inducible factor-2alpha in bovine arterial endothelial cells.

Hypoxia-inducible factor (HIF)-2alpha is a recently identified hypoxia-inducible transcription factor abundantly expressed in vascular endothelial cells. As well as HIF-1alpha, HIF-2alpha forms a heterodimeric complex with the aryl hydrocarbon receptor nuclear translocator and upregulates hypoxia-inducible genes such as vascular endothelial growth factor. We found in this study that using green fluorescent protein (GFP) fusion constructs, the subcellular localization of HIF-2alpha was different from that of HIF-1alpha in bovine arterial endothelial cells (BAEC). HIF-1alpha was localized in the cytoplasm under normoxic cells and translocated from the cytoplasm into the nucleus in response to hypoxic induction. In contrast, HIF-2alpha was clearly localized in the nucleus of BAEC even under normoxic conditions. The regulation of HIF-2alpha might differ from that of HIF-1alpha in BAEC. We further showed that nuclear localization of HIF-2alpha was inhibited by either deletion or a single amino acid substitution within the C-terminal end of the protein. The amino acid sequence surrounding Lys737 and Arg738 functions as a nuclear localization signal of HIF-2alpha.

Amino Acid Motifs↗

PubMed1999

Ectopic pharynxes arise by regional reorganization after anterior/posterior chimera in planarians.

To elucidate the mechanisms underlying pharynx regeneration in planarians, we transplanted pieces excised from various regions of the body into the prepharyngeal or postpharyngeal region, since it has been shown that such transplantation experiments can induce ectopic pharynx formation. We confirmed the ectopic formation of pharynxes by expression of the myosin heavy chain gene specific to pharynx muscles (DjMHC-A). To investigate the cellular events after grafting, we also stained such transplanted worms by in situ hybridization using neuronal cell- and mucous producing cell-type-specific marker genes which can detect formation of brain and prepharyngeal region, respectively. When the head piece was transplanted into the tail region, ectopic formation of the head, prepharyngeal and pharynx region was observed in the postpharyngeal region anterior to the graft, while these organs were formed in the reversed polarity along the anterior-posterior (A-P) axis. Furthermore, in the tail region posterior to the graft, ectopic formation of the prepharyngeal and pharynx region was observed. In the reverse combination, when a tail piece was transplanted into the prepharyngeal region, ectopic formation of prepharyngeal and pharynx region was observed in the region between the head and the graft, and an additional ectopic pharynx was also formed in reverse polarity in the region between the graft and host pharynx. These results clearly indicated that ectopic pharynxes were formed as a consequence of the regional reorganization induced by interaction between the host and graft. Furthermore, chimeric analyses demonstrated that the cells participating in ectopic pharynx formation were not exclusively derived from the host or donor cells in the worm, suggesting that the stem cells of the host and donor may change their differentiation pattern due to altered regionality. To further investigate if regional reorganization is induced after grafting, expression of a Hox gene was analyzed in the transplanted worms by whole-mount in situ hybridization. The expression of the Hox gene along the A-P axis was apparently rearranged after grafting of the head piece into the tail region. These results suggest that grafting of the head piece may rearrange the regionality of the host tail, and that stem cells in the region newly defined as pharynx-forming may start to regenerate a pharynx.

Animals↗

PubMed1999

IgE reactivity and cross-reactivity of Japanese monkeys (Macaca fuscata) to Japanese cedar (Cryptomeria japonica) and cypress (Chamaecyparis obtusa) pollen allergens.

BACKGROUND: The natural occurrence of Japanese cedar (Cryptomeria japonica, CJ) pollinosis has been reported in Japanese monkeys (Macaca fuscata). However, the reactivity to Japanese cypress (Chamaecyparis obtusa, CO) pollen allergens in these monkeys has not yet been reported. OBJECTIVES: The present study was designed to investigate the reactivity to CO pollen allergens in monkeys sensitized to CJ pollen allergens. METHODS: Serum samples from 40 monkeys naturally sensitized to CJ pollen allergens were collected from four troops. We measured the specific IgE to CO pollen allergens and examined the reactivity to the allergens by intradermal test. Cross-reactivity between CJ and CO pollen allergens was examined by ELISA inhibition method. Furthermore, we examined the sensitivity to the allergens by histamine release assay from leucocytes. RESULTS: All 40 monkeys had specific IgE to crude and purified major allergens (Cha o 1) of CO pollen. The monkeys showed a positive reaction to CO pollen allergens in the intradermal test. Allergenic cross-reactivity between Cha o 1 and Cry j 1 (a major allergen in CJ pollen) was also observed. Specific histamine release to both the major allergens was noted in two monkeys with CJ pollinosis. CONCLUSION: Japanese monkeys sensitized to Japanese cedar pollen allergens also demonstrate reactivity to Japanese cypress pollen allergens.

Allergens↗

PubMed1999

Sensitization to grass, ragweed, mugwort pollen allergens in Japanese monkeys (Macaca fuscata): preliminary report.

BACKGROUND: The natural occurrence of Japanese cedar (CJ, Cryptomeria japonica) pollinosis has been reported in Japanese monkeys (Macaca fuscata). Furthermore, most of these monkeys with CJ pollinosis have immunoglobulin (Ig) E sensitization to Japanese cypress (Chamaecyparis obtusa) pollen. However, specific IgE to other pollens has not yet been reported. OBJECTIVES: The present study was designed to investigate IgE sensitization of Japanese monkeys to grass, ragweed, and mugwort pollen. METHODS: Serum samples from 47 monkeys as a general population in one troop were collected at random. We measured specific IgE to grass, ragweed and mugwort pollen. Next, 10 monkeys with CJ pollinosis from the same troop were also examined for their IgE sensitization to grass, ragweed, and mugwort pollen. RESULTS: Of 47 monkeys, 13 (28%) had specific IgE to CJ pollen, 15 (32%) to grass pollen, five (11%) to ragweed pollen, and three (6%) to mugwort pollen. Furthermore, CJ pollinosis monkeys seemed to be sensitized to these pollen allergens with higher frequency; of 10 monkeys, 10 (100%) had specific IgE to CJ pollen, six (60%) to grass pollen, four (40%) to ragweed pollen, and two (20%) to mugwort pollen. CONCLUSION: Japanese monkeys had specific IgE to grass, ragweed, and mugwort pollen in addition to CJ pollen.

Allergens↗

PubMed1999

The incidence of Japanese cedar pollinosis and sensitization to the pollen allergens among Japanese monkeys in a troop.

The natural occurrence of Japanese cedar (Cryptomeria japonica; CJ) pollinosis has been reported in Japanese monkeys (Macaca fuscata), an appropriate animal model for developing antipollinosis therapies. However, there has been no study on the incidence of Japanese cedar pollinosis in monkeys. To evaluate the incidence of CJ pollinosis in Japanese monkeys, we investigated the presence of pollinosis symptoms among monkeys in a troop, and the response to CJ allergens in pollinosis monkeys. We examined the presence of pollinosis symptoms in 272 monkeys in a troop throughout the CJ pollination season (February to April). Of the 272 monkeys, 21 (7.7%) showed pollinosis symptoms during the CJ pollen season. Blood samples were taken from the 21 monkeys that showed pollinosis symptoms and were tested for the presence of immunoglobulin E (IgE) antibody for CJ allergens. All 21 monkeys with CJ pollinosis had anti-CJ IgE. Of the 21 monkeys, peripheral blood mononuclear cells (PBMC) could be taken from 12, all of which showed CJ allergen-specific PBMC proliferation. The incidence of CJ pollinosis in a troop was 7.7%. The monkeys with CJ pollinosis demonstrated specific IgE and PBMC proliferation for CJ allergens.

Allergens↗

PubMed1999

The incidence of japanese cedar pollinosis and sensitization to the pollen allergens among Japanese monkeys in a troop.

Allergens↗