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Biomedical subjects

S Shimomura

Publications and source records attributed to S Shimomura.

At least 19 recordsLinked to original sources
PubMed2001

The role of auxin-binding protein 1 in the expansion of tobacco leaf cells.

Tobacco leaf was used to investigate the mechanism of action of auxin-binding protein 1 (ABP1). The distributions of free auxin, ABP1, percentage of leaf nuclei in G2 and the amount of auxin-inducible growth were each determined in control tobacco leaves and leaves over-expressing Arabidopsis ABP1. These parameters were compared with growth of tobacco leaves, measured both spatially and temporally throughout the entire expansion phase. Within a defined window of leaf development, juvenile leaf cells that inducibly expressed Arabidopsis ABP1 prematurely advanced nuclei to the G2 phase. The ABP1-induced increase in cell expansion occured before the advance to the G2 phase, indicating that the ABP1-induced G2 phase advance is an indirect effect of cell expansion. The level of ABP1 was highest at the position of maximum cell expansion, maximum auxin-inducible growth and where the free auxin level was the lowest. In contrast, the position of maximum cell division correlated with higher auxin levels and lower ABP1 levels. Consistent with the correlations observed in leaves, tobacco cells (BY-2) in culture displayed two dose-dependent responses to auxin. At a low auxin concentration, cells expanded, while at a relatively higher concentration, cells divided and incorporated [3H]-thymidine. Antisense suppression of ABP1 in these cells dramatically reduced cell expansion with negligible effect on cell division. Taken together, the data suggest that ABP1 acts at a relatively low level of auxin to mediate cell expansion, whereas high auxin levels stimulate cell division via an unidentified receptor.

Arabidopsis↗
PubMed2000

Local treatment of AIDS-associated bulky Kaposi's sarcoma in the head and neck region.

Kaposi's sarcoma (KS) is frequently seen in the head and neck regions of HIV-infected patients. We report two cases of patients with AIDS who consulted the ENT clinic. One patient came to our clinic complaining of abnormal sensations in the pharynx, and dysphasia due to a gross KS in the oropharynx. The excision of the tumor improved the difficulty of swallowing. The other patient complained of masticatory problems and tongue pain due to a bulky KS on the dorsal side of the tongue. We treated the tongue lesion with intralesional chemotherapy. The administration of intralesional vinblastine resulted in a partial response. Unless systemic chemotherapy is effective enough to improve a functional disorder, it is thought that local therapy employing excision or intralesional chemotherapy is one of the common therapeutic option of the otolaryngologist, because this treatment avoids severe side effects caused by systemic chemotherapy or radiotherapy.

Acquired Immunodeficiency Syndrome↗
PubMed2000

Investigation of TTV by in situ hybridization in patients with chronic hepatitis.

To clarify whether TT virus (TTV) was present in liver tissues, 12 liver tissue samples from patients with chronic hepatitis positive for TTV in their serum and 11 samples from serum-negative patients were obtained by needle biopsies and investigated using in situ hybridization. Positive staining was observed in nine (75%) of 12 cases positive for TTV (serum-positive group) and three (27.3%) of 11 cases negative for TTV (serum-negative group) (P=0.061). Three kinds of staining patterns were observed: nuclear, cytoplasmic and both. In 58.3% (7/12) of the patients positive for TTV staining, the stained areas were found in both the nucleus and cytoplasm. Only cytoplasmic staining was observed in three cases from the serum-positive group. Only nuclear staining was observed in two cases from the serum-negative group. No significant differences were found in the clinical background between the in situ hybridization-positive and -negative groups, and between the serum-positive and -negative groups. The present study shows that TTV exists in the liver tissue, especially in hepatocytes, of chronic hepatitis patients and that the localization of TTV in the cell is different from case to case, although why this is so remains to be clarified.

Journal Article↗
PubMed2000

Transcription factor Sp3 activates the liver/bone/kidney-type alkaline phosphatase promoter in hematopoietic cells.

The promoter region of the liver/bone/ kidney-type alkaline phosphatase gene was examined to define the cis-acting regulatory sequences and transcription factors responsible for its expression in hematopoietic cells. Transient transfection experiments revealed that regions deleted up to -154 base pairs upstream from the transcription initiation site had significant activities to induce bacterial chloramphenicol acetyltransferase gene. The shortest DNA fragment was found to contain three GC boxes in addition to a TATA box. Electrophoretic mobility shift assay and Southwestern analysis showed that Sp3 could bind to the fragment. Western blot analysis also detected Sp3 protein in eluate from the DNA probe mixed with the nuclear extracts. Through the use of Drosophila Schneider cells that lack the Sp1 family of transcription factors, Sp3 was shown to activate the basal promoter in a dose-dependent manner. When the amount of Sp3 was limited, the most proximal GC box was found to be critical for the basal promoter activity.

Alkaline Phosphatase↗
PubMed1999

Characterization of auxin-binding protein 1 from tobacco: content, localization and auxin-binding activity.

There is evidence that auxin-binding protein 1 (ABP1) is an auxin receptor on the plasma membrane. Maize (Zea mays L.) possesses a high level of auxin-binding activity due to ABP1, but no other plant source has been shown to possess such an activity. We have analyzed the ABP1 content of tobacco (Nicotiana tabacum L.) to examine whether or not the ABP1 content of maize is exceptionally high among plants. The ABP1 content of tobacco leaves was shown by quantitative immunoblot analysis to be between 0.7 and 1.2 microg ABP1 per gram of fresh leaf. This value is comparable to the reported value in maize shoots, indicating that ABP1 is present at a similar level in both monocot and dicot plants. The ABP1 content of tobacco leaves was increased up to 20-fold by expression of a recombinant ABP1 gene, and decreased to half of the original value by expression of the antisense gene. Although ABP1 was found mainly in the endoplasmic reticulum fraction, a secreted protein showing a molecular size and epitopes similar to intracellular ABP1 was also detected in the culture medium of tobacco leaf disks. The secretion of this protein was dependent on the expression level of the ABP1 gene.

Animals↗
PubMed1998

Cloning and expression of two genes encoding auxin-binding proteins from tobacco.

Two genes encoding the auxin-binding protein (ABP1) of tobacco (Nicotiana tabacum L.), both of which possess the characteristics of a luminal protein of the endoplasmic reticulum (ER), were isolated and sequenced. These genes were composed of at least five exons and four introns. The two coding exons showed 95% sequence homology and coded for two precursor proteins of 187 amino acid residues with molecular masses of 21,256 and 21,453 Da. The deduced amino acid sequences were 93% identical and both possessed an amino-terminal signal peptide, a hydrophilic mature protein region with two potential N-glycosylation sites and a carboxyl-terminal sorting signal, KDEL, for the ER. Restriction mapping of the cDNAs encoding tobacco ABP1, previously purified by amplification of tobacco cDNA libraries by polymerase chain reaction (PCR) using specific primers common to both genes, indicated that both genes were expressed, although one was expressed at a higher level than the other. Genomic Southern blot hybridization showed no other homologous genes except for these two in the tobacco genome. The apparent molecular mass of the mature form of tobacco ABP1 was revealed to be 25 kDa by SDS polyacrylamide gel electrophoresis using affinity-purified anti (tobacco ABP1) antibodies raised against a fusion protein with maltose-binding protein. Expression of the recombinant ABP1 gene in transgenic tobacco resulted in accumulation of the 25 kDa protein. A single point mutation of an amino acid residue at either of the two potential N-glycosylation sites resulted in a decrease in the apparent molecular mass and produced a 22 kDa protein. Mutations at both sites resulted in the formation of a 19.3 kDa protein, suggesting that tobacco ABP1 is glycosylated at two asparagine residues.

Amino Acid Sequence↗
PubMed1997

Age-related changes in the compound action potentials of the eighth nerve in guinea pigs.

The eighth nerve compound action potential (CAP) in 95 guinea pigs was measured using click stimuli to investigate age-related changes in their neural auditory thresholds. The animals were separated into three groups: group A (n = 43, 86 ears; 2-4 months old); group B (n = 29; 58 ears, 13-15 months old); and group C (n = 23; 46 ears, 23-25 months old). With increasing age, a gradual elevation of CAP thresholds was clearly seen among the three groups. The negative peak (N1) latencies of the CAP were prolonged, and the N1 amplitudes of the CAP decreased. There were significant differences in N1 latencies among the three groups and in N1 amplitudes between groups A and B, and between groups A and C. However, the rate of decline of the thresholds as well as the input-output function curves of the CAP varied in some of the oldest animals, suggesting that there were some individual differences in degenerative aging processes of the auditory system.

Acoustic Stimulation↗
PubMed1997

Laparoscopic prediction of hepatocellular carcinoma in cirrhosis patients.

Previously, laparoscopic studies have not been successful in predicting the occurrence of small hepatocellular carcinoma because cirrhotic patients had not been separated into groups of those who developed small hepatocellular carcinoma under 3 cm in diameter, and those who did not. Retrospective examination with better separation of the two groups gave improved results. Of the 26 laparoscopic findings, only the presence of large complex regenerative nodules was closely associated with the occurrence of subclinical small hepatocellular carcinoma. The study of other cirrhotic patients with and without large complex regenerative nodules gave a cumulative hepatocellular carcinoma occurrence rate of 73% for patients who had these nodules by the third year after laparoscopy. In contrast, the rate for patients without such nodules was 6%, showing a significant difference (P < 0.05) between the two groups. We concluded that the laparoscopic finding of large complex regenerative nodules of liver cirrhosis can be used to predict the occurrence, or a complication, of subclinical small hepatocellular carcinoma.

Carcinoma, Hepatocellular↗
PubMed1996

Age-related alterations in the auditory brainstem responses and the compound action potentials in guinea pigs.

The auditory brainstem response (ABR) and the eight nerve compound action potential (CAP) were measured using click click stimuli to investigate the age-related alteration in the auditory function in 66 guinea pigs consisting of four age groups. With advancing age, a gradual elevation of the thresholds in both the ABR and CAP was clearly seen, together with the prolonged latencies for waves I, II, III, and IV to clicks at 95 dBpeSPL in the ABR. There were some individual differences in either threshold elevation or latency prolongation of both the ABR and CAP in aged guinea pigs. These findings suggest that the effect of individual differences on degenerative aging processes of the auditory system should be considered in selected aged animals, although a significant elevation of the neural auditory threshold is clearly found with advancing age as a whole.

Action Potentials↗
PubMed1996

An ultrastructural study of goblet cells in rat nasal mucosa as revealed by the quick-freezing method.

In order to clarify the natural ultrastructure of goblet cells in the rat nasal mucosa, they were examined by the quick-freezing and freeze-substitution (QF-FS) or deep-etching (QF-DE) methods for comparison with conventional fixation methods. Some nasal mucosal tissues were unstimulated; others were stimulated with acetylcholine or substance P. The QF-FS method yielded fewer artefacts on transmission electron microscopy than conventional fixation methods. In the stimulated goblet cells, most of the secretory granules appeared to be loose in the matrix and more distorted in shape. By the QF-DE method, they were observed 3-dimensionally to be larger in size and aggregated together. In contrast, the secretory granules in the unstimulated goblet cells were mostly round and small, and separate from each other. It is concluded that the ultrastructure of secretory granules is artefactually modified by conventional fixation methods and that granule structure in goblet cells alters during the secretory process.

Acetylcholine↗
PubMed1995

A novel intracellular antigen in HL-60 cells that changes in molecular weight after granulocytic and monocytic differentiation.

The present study reports the identification and partial characterization of a novel antigen with M(r) 100,000 by a monoclonal antibody (D29A8) that was obtained by immunizing BALB/c mice with nuclei of HL-60 cells. D29A8 detected mainly a nucleolar macromolecule with M(r) 100,000 (p100). On the other hand, when HL-60 cells were induced to differentiate either into a granulocytic or monocytic pathway, the antibody detected mainly a cytoplasmic macromolecule with M(r) 95,000 (p95). Since two subtypes of the antigen (p100 and p95) appear to be present in the same cells that differ in the stage of cell differentiation, the antigen may play an important role in cellular differentiation.

Animals↗
PubMed1995

Inhibition of mucociliary clearance of the eustachian tube by leukotrienes C4 and D4.

The effect of leukotrienes C4 (LTC4) and D4 (LTD4) and prostaglandin E2 (PGE2) on mucociliary clearance of the eustachian tube was investigated in vitro and in vivo. Normal ciliated epithelium was obtained from the eustachian tube of guinea pigs and incubated separately with LTC4, LTD4, and PGE2 at concentrations of 10(-8) mol/L and 10(-6) mol/L. Ciliary activity was measured photoelectrically. Leukotriene D4 progressively inhibited ciliary activity, while PGE2 promoted it. Leukotriene C4 also induced ciliary inhibition. One milliliter each of 10(-5) mol/L LTC4, LTD4, and PGE2 was directly injected into the tympanic bullae of chinchillas under anesthesia. The middle ears were examined by otomicroscopy, tympanometry, and auditory brain stem response over time. Clearance of middle ear effusion was delayed by LTC4 and LTD4, as compared with PGE2 and the control. These findings indicate that LTC4 and LTD4 inhibit mucociliary clearance of the eustachian tube.

Animals↗
PubMed1995

Relation between markers for viral hepatitis and clinical features of Japanese patients with hepatocellular carcinoma: possible role of alcohol in promoting carcinogenesis.

To assess the relationship between hepatitis virus markers and the clinical features of hepatocellular carcinoma (HCC), we measured markers for hepatitis B virus (HBV) and hepatitis C virus (HCV) in 88 Japanese patients with HCC. Twelve (14%) patients were HBsAg-positive and 67 (76%) were anti-HCV-positive (both c100-3 and c11/c7). HCV-RNA was detected in 8 (38%) of the 21 anti-HCV-negative patients by PCR, so that 75 patients (85%) were infected with HCV. Of the HBsAg-negative patients infected with HCV with no history of blood transfusion, the mean age of the alcoholics (consumption > 80 g ethanol daily for at least 10 years) was lower than that of the non-alcoholics (60 years vs. 65 years, P < 0.05). Among the HBsAg-negative and anti-HCV (or HCV-RNA)-positive patients with a history of blood transfusion, the mean interval between the time of blood transfusion and the diagnosis of HCC in the alcoholics was shorter (21 years) than that in the nonalcoholics (27 years), but the difference was not statistically significant. We conclude that infection by both HCV and HBV may play a role in the development of HCC, and that alcohol consumption may promote carcinogenesis.

Adult↗
PubMed1994

Aspartate aminotransferase-linked immunoglobulin complexes in serum of a patient with primary biliary cirrhosis.

A 51-year-old woman who had been treated for primary biliary cirrhosis (PBC) was admitted to our hospital for evaluation of unexplained, isolated, persistently increased aspartate aminotransferase (AST) activity. Results of laboratory tests on admission showed: AST 171 KU, alanine aminotransferase 28 KU, and anti-mitochondrial titer 1/1280. Results of hepatitis B surface antigen (HBs Ag) and hepatitis C virus antibody (HCV Ab; C100-3) assays were negative. Histology of a liver biopsy specimen was compatible with a diagnosis of PBC (stage III of Scheuer's classification). The molecular size of serum AST was estimated to be more than 500,000 by high-performance size-exclusion liquid chromatography. Electrophoretic analysis showed an abnormal band of AST between supernatant AST (sAST) and mitochondrial AST (mAST), which band was characteristic of AST-immunoglobulin complexes (AST-Ig). Ouchterlony double-diffusion and immunoprecipitation tests identified the immunoglobulin component as IgM. The presence of AST-Ig appeared to be responsible for the elevated serum AST.

Aspartate Aminotransferases↗
PubMed1994

Turn-over of PAF in cultures of human paranasal sinus mucosa.

The change of PAF concentration in the culture medium was investigated by radioimmunoassay when 10(-8) M PAF or 10(-8) M lyso-PAF was incubated with a piece of normal human paranasal sinus mucosa. The PAF concentration in the medium of the former group was halved within 11.3 min and reduced to less than 5% of the initial concentration within 60 min. However, there was no significant difference in the reduction of PAF concentrations in the medium between groups with or without the mucosa. When 10(-8) M lyso-PAF was incubated with a piece of mucosa, PAF gradually increased and reached the maximum of 0.36 x 10(-8) M at 20 min, and thereafter quickly decreased to a non-detectable level.

Cells, Cultured↗