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T Hoshi

Publications and source records attributed to T Hoshi.

At least 73 records · Page 4Linked to original sources
PubMed1998

MIB-1 and p53 immunocytochemistry for differentiating pilocytic astrocytomas and astrocytomas from anaplastic astrocytomas and glioblastomas in children and young adults.

AIMS: To establish whether MIB-1 and p53 staining are useful for differentiating pilocytic astrocytomas and astrocytomas from anaplastic astrocytomas and glioblastomas. This study was restricted to children and young adults under 30 years of age because of the differences in p53 mutations between paediatric and adult astrocytomas. METHODS AND RESULTS: Forty-five astrocytic tumours, including 18 pilocytic astrocytomas, 14 astrocytomas, four anaplastic astrocytomas and nine glioblastomas, from 45 children and young adults, between 1 and 29 years (mean 11 years) of age, were examined pathologically, and sections from paraffin-embedded blocks were used for MIB-1 and p53 immunostaining. The MIB-1 labelling index and the frequency and intensity of p53 staining in both the pilocytic astrocytoma and the astrocytoma group were significantly lower than in the anaplastic astrocytoma plus glioblastoma group (P < 0.001). In 11.1% (two of 18) of pilocytic astrocytomas and 42.9% (six of 14) of astrocytomas, immunoreactivity of either MIB-1 or p53 staining was of almost the same intensity as that of anaplastic astrocytomas and glioblastomas. However, in these cases, results using both MIB-1 and p53 stain differed from those for anaplastic astrocytomas and glioblastomas. CONCLUSIONS: MIB-1 and p53 co-staining is very useful for differentiating pilocytic astrocytomas and astrocytomas from anaplastic astrocytomas and glioblastomas. However, MIB-1 or p53 staining alone cannot differentiate pilocytic astrocytomas and astrocytomas from anaplastic astrocytomas and glioblastomas.

Adolescent↗
PubMed1998

[A case of the CHARGE association with failed tracheal intubation].

We experienced a patient with the CHARGE association whose trachea could not be intubated in spite of attempts of laryngoscopy by four experienced anesthesiologists. Laryngeal fiberscope and neck X-ray examination carried out after the surgery, revealed the obvious enlargement of adenoid and tonsils, pressing the epiglottis to the posterior wall of the larynx. Although it is unknown whether enlargement of adenoid and tonsils are specific to the CHARGE association or not, patients with the CHARGE association are considered to have difficult airway. Preanesthetic evaluation of airway is indispensable for anesthesia in the patients with the CHARGE association.

Adenoids↗
PubMed1997

Modulation of potassium channel function by methionine oxidation and reduction.

Oxidation of amino acid residues in proteins can be caused by a variety of oxidizing agents normally produced by cells. The oxidation of methionine in proteins to methionine sulfoxide is implicated in aging as well as in pathological conditions, and it is a reversible reaction mediated by a ubiquitous enzyme, peptide methionine sulfoxide reductase. The reversibility of methionine oxidation suggests that it could act as a cellular regulatory mechanism although no such in vivo activity has been demonstrated. We show here that oxidation of a methionine residue in a voltage-dependent potassium channel modulates its inactivation. When this methionine residue is oxidized to methionine sulfoxide, the inactivation is disrupted, and it is reversed by coexpression with peptide methionine sulfoxide reductase. The results suggest that oxidation and reduction of methionine could play a dynamic role in the cellular signal transduction process in a variety of systems.

Amino Acid Sequence↗
PubMed1997

Voltage-dependent gating characteristics of the K+ channel KAT1 depend on the N and C termini.

We studied how the C and N termini of the plant K+ channel KAT1 influence the voltage-dependent gating behavior by generating C- and N-terminal deletion mutants. Functional expression was observed only when C-terminal deletions were downstream of the putative cyclic nucleotide binding site. Treatments of oocytes expressing KAT1 channels with anticytoskeletal agents indicated that intact microtubules are important for functional expression. C-terminal deletions altered the voltage sensitivity of the KAT1 channel with greater deletions resulting in smaller equivalent charge movements. In contrast, a deletion in the N terminus (delta20-34) shifted the half-activation voltage by approximately -65 mV without markedly affecting the number of equivalent charges. The results reveal novel roles of the N and C termini in regulation of the voltage-dependent gating of KAT1.

Ion Channel Gating↗
PubMed1997

Plant K+ channel alpha-subunits assemble indiscriminately.

In plants a large diversity of inwardly rectifying K+ channels (K(in) channels) has been observed between tissues and species. However, only three different types of voltage-dependent plant K+ uptake channel subfamilies have been cloned so far; they relate either to KAT1, AKT1, or AtKC1. To explore the mechanisms underlying the channel diversity, we investigated the assembly of plant inwardly rectifying alpha-subunits. cRNA encoding five different K+ channel alpha-subunits of the three subfamilies (KAT1, KST1, AKT1, SKT1, and AtKC1) which were isolated from different tissues, species, and plant families (Arabidopsis thaliana and Solanum tuberosum) was reciprocally co-injected into Xenopus oocytes. We identified plant K+ channels as multimers. Moreover, using K+ channel mutants expressing different sensitivities to voltage, Cs+, Ca2+, and H+, we could prove heteromers on the basis of their altered voltage and modulator susceptibility. We discovered that, in contrast to animal K+ channel alpha-subunits, functional aggregates of plant K(in) channel alpha-subunits assembled indiscriminately. Interestingly, AKT-type channels from A. thaliana and S. tuberosum, which as homomers were electrically silent in oocytes after co-expression, mediated K+ currents. Our findings suggest that K+ channel diversity in plants results from nonselective heteromerization of different alpha-subunits, and thus depends on the spatial segregation of individual alpha-subunit pools and the degree of temporal overlap and kinetics of expression.

Arabidopsis Proteins↗
PubMed1997

Dihydropyridine action on voltage-dependent potassium channels expressed in Xenopus oocytes.

Dihydropyridines (DHPs) are well known for their effects on L-typed voltage-dependent Ca2+ channels, However, these drugs also affect other voltage-dependent ion channels, including Shaker K+ channels. We examined the effects of DHPs on the Shaker K+ channels expressed in Xenopus oocytes. Intracellular applications of DHPs quickly and reversibly induced apparent inactivation in the Shaker K+ mutant channels with disrupted N- and C-type inactivation. We found that DHPs interact with the open state of the channel as evidenced by the decreased mean open time. The DHPs effects are voltage-dependent, becoming more effective with hyperpolarization. A model which involves binding of two DHP molecules to the channel is consistent with the results obtained in our experiments.

Animals↗
PubMed1997

Relative changes of MIB1 and PC10 labeling indexes in cell kinetics during radiotherapy for cervical squamous cell carcinoma.

To assess the changes in cell kinetics during radiotherapy (RT) in terms of the MIB1 and PC10 labeling indexes of cancer cells, a total of 230 biopsy specimens taken from 76 consecutive patients with cervical squamous cell carcinoma treated with RT was investigated. The MIB1 and PC10 indexes represent the growth fraction and proliferative activity, respectively. The MIB1 index ranged from 11 to 67% (mean value: 38%) before RT, from 21 to 86% (50%) at 5.4 Gy, from 15 to 85% (53%) at 9 Gy, and from 0 to 69% (26%) at 27 Gy. The PC10 index ranged from 4 to 46% (23%) before RT, from 5 to 62%, (26%) at 5.4 Gy, from 6 to 63% (23%) at 9 Gy, and from 0 to 35% (11%) at 27 Gy. The correlational relationships between the increment of both indexes during RT (delta index) and the index before RT were analyzed on an individual basis. The delta index was calculated by the index at various doses during RT minus the index before RT. Negative linear relationships were observed between the delta MIB1 index at 9 Gy or delta MIB1 index at 27 Gy and the MIB1 before RT, and also between the delta PC10 index at 9 Gy or delta PC10 index at 27 Gy and the PC10 index before RT. The linear regression coefficient values showed more than 0.5 (0.511 to 0.682) with statistical significance. According to these results, it was suggested that the cervical cancers of lower proliferative activity showed greater increases in growth fraction and proliferative activity by irradiation than those of higher proliferative tumors. These findings suggest that reversal patterns of changes in cell kinetics including growth fraction and proliferative activity took place in the early period of RT for cervical squamous cell carcinomas. The study of changes in cell cycle kinetics in human tumors during RT may have potential impact on the further development of RT.

Adult↗
PubMed1997

Analysis of cell damage and proliferation in Helicobacter pylori-infected human gastric mucosa from patients with gastric adenocarcinoma.

Helicobacter pylori (HP) infection, a cause of multifocal atrophic gastritis, is considered an important factor related to the evolution of the human gastric mucosa from normal to intestinal-type adenocarcinoma. We examined cell proliferation and both double and single strand DNA damage in situ in 35 patients undergoing gastrectomy for adenocarcinoma with HP-infected gastric mucosa by immunolocalization of Ki-67, terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling, and in situ nick translation. We also studied the distribution of intraepithelial neutrophils by elastase immunolocalization. HP infection was confirmed in all cases by serum anti-HP antibodies, ureas testing, and histopathological examination. HP-infected gastric mucosa was classified according to the degree of inflammation and intestinal metaplasia. Ki-67, terminal deoxynucleotidyl transferase-mediated labeling, in situ nick translation, and intraepithelial neutrophil indices all increased with the progression of gastritis and were highest in glands with incomplete intestinal metaplasia. All indices were lowest in gastric glands with complete intestinal metaplasia. Significant positive correlations were observed among these markers. Increased proliferative activity in HP-associated chronic gastritis in response to cell damage or injury was clearly demonstrated, suggesting that both HP-associated toxins and intraepithelial neutrophils are important in HP-related gastric epithelial injury. Increased cell turnover associated with incomplete intestinal metaplasia may result in DNA instability and subsequent development of intestinal-type gastric adenocarcinoma in HP-infected mucosa.

Adenocarcinoma↗
PubMed1996

Analysis of response to radiation therapy of patients with cervical adenocarcinoma compared with squamous cell carcinoma. MIB-1 and PC10 labeling indices.

BACKGROUND: The MIB-1 monoclonal antibody is a marker of cycling cells and the PC10 monoclonal antibody is a marker of proliferating cell nuclear antigen in paraffin sections. This study was conducted to elucidate the difference in response to radiotherapy (RT) between cervical adenocarcinomas and squamous cell carcinomas, focusing on cell proliferation. METHODS: A total of 196 biopsy specimens taken from the cervical carcinomas of 14 consecutive patients with adenocarcinoma and 62 patients with squamous cell carcinoma before and after RT at doses of 9 and 27 Grays (Gy) were investigated for MIB-1 and PC10 immunoreactivities. RESULTS: In adenocarcinomas, the mean MIB-1 labeling indices before and after RT at 9 and 27 Gy were 28%, 21%, and 26%, respectively, whereas the mean PC10 labeling indices were 15%, 13%, and 14%, respectively. In squamous cell carcinomas, the mean MIB-1 labeling indices before and after RT at 9 and 27 Gy were 38%, 53%, and 26%, respectively, and the mean PC10 labeling indices were 23%, 23%, and 11%, respectively. CONCLUSIONS: Cervical adenocarcinomas have a lower cycling cell population and their indices show no change during RT. Squamous cell carcinomas have a higher cycling cell population and show a transient increase of the MIB-1 cycling cell population at 9 Gy of RT. These findings suggest a difference in response to RT between adenocarcinomas and squamous cell carcinomas.

Adenocarcinoma↗
PubMed1996

Effects of aging on the microclimate pH of the rat jejunum.

The acidic microclimate layer in the vicinity of the cell surface of mammalian jejunum is important for absorption of some nutrients, such as small peptides and folate. The present study was undertaken to investigate the effect of aging on the cell surface pH (microclimate pH) of the jejunum of rats. The microclimate pH was measured in vitro in superfused preparations using single-barreled pH-sensitive microelectrodes filled with a liquid ion exchanger. The thickness of the microclimate layer was estimated by reading the distance of microelectrode advancements. The existence of a microclimate pH in the jejunum was confirmed in the senescent rats, but the value of the microclimate pH was significantly higher in the senescent (24 mo) rats (6.52 +/- 0.02) than in the young-adult (6 mo) rats (6.09 +/- 0.01) (P < 0.01). Na+ removal from the perfusate or the addition of amiloride elevated the pH in the senescent rats as well as in the young-adult rats. The microclimate layer was slightly thinner in the senescent rats than in the young-adult rats. The acidity of the microclimate layer of intestinal surface is lower in senescent animals than in the young-adult ones. One of reasons for this is the thinner mucus layer in senescent animals.

Aging↗
PubMed1996

Heteromultimeric interactions among K+ channel subunits from Shaker and eag families in Xenopus oocytes.

Heteromultimeric interactions of K+ channel subunits across different families have been thought to contribute to the functional diversity of ionic currents, as suggested by previous genetic evidence. We present here direct demonstration in Xenopus oocytes that subunits from distinct eag and Shaker families functionally interact, most likely as heteromultimeric channels. Coexpression with eag accelerates the inactivation and slows the recovery from inactivation of the transient Shaker current. Site-directed mutagenesis indicates that the eag carboxyl terminus is crucial for this interaction, exerting effects preferentially on N-type inactivation. Many members of the eag and Shaker families have now been identified and their human homologs implicated in cardiac and neurological disorders. Studies on channel subunit interactions may prove important in understanding the disease pattern and the complex functions of the brain.

Alternative Splicing↗
PubMed1996

Effects of aging on the regulation of intracellular pH in the rat jejunum.

Jejunal villus cells from young-adult (6 months) and senescent (24 months) male Wistar rats were studied to evaluate the effect of aging on intracellular pH (pHi) regulation. pHi was measured by quantitative fluorescence microscopy by using BCECF-AM [2',7'-bis(carboxyethyl)-5(6)-carboxy-fluorescein acetoxy methylester] under basal conditions and after inducing cytoplasmic acidification with pulsed NH4Cl. In the senescent rats, the recovery rate from the acidified levels was significantly lower than that in the young-adult rats (.208 +/- .005 vs .255 +/- .004 pH units/min). The relationship between pHi recovery and external Na+ concentration followed Michaelis-Menten type kinetics, the maximum velocity (Vmax) of alkalinization being significantly lower in the senescent rats than in the young-adult rats (.227 +/- .033 vs .297 +/- .024 pH units/min). These results indicate that the recovery of pHi from an acidic level was slower in the senescent rats, due to the reduced activity of Na+/H+ exchange as revealed by the decreased Vmax value.

Aging↗
PubMed1996

[Public health nurse staffing requirements for health examination of infants and children in municipalities of Japan].

In accordance with the Maternal and Child Health Service Act, public health centers and municipalities offer health education, health counseling, health examinations, and home visits for children and their mothers in their jurisdiction. On the basis of the new Maternal and Child Health Service Act, municipalities will have the responsibility to effectively promote health examination for three-year-old children beginning in 1997. To provide health examinations to infants and children, establishing a health personnel system, especially the public health nurse program, is extremely important. The purpose of this study is to determine fundamental facts concerning health manpower development among public health nurses in the municipalities, by reviewing research on health examinations for both infants and children. To determine personnel staffing requirements necessary for health examinations of infants and children in the municipalities of Japan, pertinent references were systematically reviewed. The main results are as follows; 1) The correlation coefficients between the total working hours of the public health nurse for MCH and the population per area and number of birth per year were significantly positive. 2) Total working hours for health examination of three-year-old children per 100 births per year, by the public health nurse were 143 hours, of which 79% were spent just for performing the examination itself. 3) Due to the lack of health personnel, rural towns and villages with small populations required public health nurses to be assisted by other staff, most often public health nurses from prefectural Health Centers. For example, in those areas with a population of less than 3,000, 43% of the total volume of work performed by public health nurses during the health examinations of three-year-old children required the assistance of prefectural public health nurses. 4) On the other hand, in those areas with populations more than 10,000, 88% of the total volume of work required to be performed by public health nurses during the health examinations for three-year-old children was covered by municipal public health nurses. 5) When the total number of working hours of the public health nurse for Maternal and Child Health was divided into the four parts of planning, implementation, evaluation and training, 86.7% of working hours were spent on implementation itself. 6) In those cities designated by the Government, the health personnel system was sufficient to carry out these health examinations. 7) It was found that in towns and villages with small populations, the health examinations for infants and children can be better carried out in combination with assistance by prefectural public health nurses. 8) The review of the findings suggests that it is important to clarify by further studies not only the relationship between the health manpower system and implementation of the health examination but also the relationship between this system and the effectiveness of the health examination in near future.

Adult↗
PubMed1996

[Pulmonary typical carcinoid with metastases to pulmonary hilar, and mediastinal lymph nodes].

A 50-year-old woman was admitted to our hospital complaining of recurrent bloody sputum and hemoptysis. Chest X-ray films showed an infiltrative shadow in the left lower lung field. Chest computed tomograms showed a nodular tumor shadow near the left B8 and this tumor shadow was found between A8 and A9 by pulmonary arteriography. Bronchoscopic examination revealed a red coagulum in the left B8 and cytologic examination of broncho alveolar lavage fluid revealed atypical squamous cells. With a clinical diagnosis of squamous cell carcinoma of the lung, a left lower lobectomy with hilar and mediastinal lymph node dissection was done. A milk-white tumor was found in the lower lobe of the resected lung. The pathological diagnosis of the resected tissue specimen was carcinoid, accompanied by pulmonary, hilar, and mediastinal lymph node metastases. Reduced immunofluorescence by Chromogranin A and serotonin staining were further evidence that the tumor was atypical. This case is very interesting in that the tumor metastasized to the lung and lymph nodes, even-though it was pathologically typical.

Carcinoid Tumor↗
PubMed1995

Controlled deposition of glucose oxidase on platinum electrode based on an avidin/biotin system for the regulation of output current of glucose sensors.

A facile method for the regulation of enzyme loading on an electrode surface has been studied using avidin and biotinylated glucose oxidase (GOx). It was demonstrated that an alternate and repeated deposition of avidin and biotinylated GOx gives a protein thin film probably composed of avidin monolayers and biotinylated GOx monolayers which are connected with each other through strong affinity between avidin and biotin moieties of the enzyme (binding constant, 10(15) M-1). Amperometric response of the glucose sensors constructed by this method was controlled stepwise and rather precisely by regulating the number of GOx layers deposited (or the loading of GOx). For example, the output current of the sensors to 1 mM glucose was enhanced to ca. 1300 and 2800 nA after deposition of 10 and 20 layers of GOx, respectively, as compared with 110 nA for the monolayer GOx sensor. The enhanced response contributed to the extension of the dynamic range of the sensors, especially at a lower glucose concentration. The response time of the sensors was satisfactorily fast (ca. 20 s), irrespective of the number of GOx layers.

Avidin↗
PubMed1995

Cooperative subunit interactions in C-type inactivation of K channels.

C-type inactivation of potassium channels is distinct from N-terminal mediated (N-type) inactivation and involves a closing of the outer mouth of the channel. We have investigated the role of the individual subunits of the tetrameric channel in the C-type inactivation conformational change by comparing the inactivation rates of channels constructed from different combinations of subunits. The relationship between the inactivation rate and the number of fast subunits is exponential, as would be predicted by a cooperative mechanism where the C-type conformational change involves all four subunits, and rules out a mechanism where a conformational change in any of the individual subunits is sufficient for inactivation. Subunit interactions in C-type inactivation are further supported by an interaction between separate mutations affecting C-type inactivation when in either the same or separate subunits.

Amino Acid Sequence↗