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H Hosoi

Publications and source records attributed to H Hosoi.

At least 19 recordsLinked to original sources
PubMed2000

Transfection with mutant p53 gene inhibits heat-induced apoptosis in a head and neck cell line of human squamous cell carcinoma.

PURPOSE: To confirm that human cancer cells show p53-dependent heat sensitivity through an apoptosis-related mechanism, we examined the heat sensitivity and Bax-mediated apoptosis after heating in a human squamous cell carcinoma cell line, SAS, with identical genetic backgrounds except for the p53 status. MATERIALS AND METHODS: We performed colony formation assay, Western blotting and analyses of apoptosis, using the SAS cells transfected with pC53-248 vector with mutant p53 gene (SAS/Trp248 cells) or the cells transfected with pCMV-Neo-Bam vector (SAS/neo cells) as a control. RESULTS: SAS/Trp248 cells showed heat resistance due to the dominant negative nature of mp53, compared with SAS/neo cells. The incidence of DNA ladders and apoptotic bodies increased markedly after heating in SAS/neo cells, but increased very little in SAS/Trp248 cells. CONCLUSION: These results suggest that heat resistance brought by mp53-transfection is p53-dependent and closely correlates with the induction of apoptosis in human squamous cell carcinomas.

Apoptosis↗
PubMed2000

N-Myc induction stimulated by insulin-like growth factor I through mitogen-activated protein kinase signaling pathway in human neuroblastoma cells.

Insulin-like growth factor I (IGF-I) stimulates proliferation, survival, and differentiation in many cell types, including pediatric neuroblastomas. The effect is mediated via the type I IGF-I receptor (IGF-IR), which is essential for growth in these cells. Several lines of evidence indicate that IGF-IR function may be particularly important in the pathogenesis of neuroblastoma. Amplification of the N-myc oncogene or overexpression of N-Myc oncoprotein has been reported to be associated with resistance to therapy and poor prognosis of neuroblastomas. It was therefore of interest to analyze whether IGF-I signaling regulated expression of N-myc in KP-N-RT human neuroblastoma cells as an experimental model that has amplified N-myc. We found that IGF-I induces N-myc mRNA and protein in the KP-N-RT with maximums of four and six times more than the basal level at 2 and 3 h after stimulation, respectively. These effects of IGF-I were blocked by a neutralizing antibody against IGF-IR (alpha-IR3). Exogenous IGF-I induced phosphorylation and activation of extracellular signal-regulated kinases p44/42 (ERK1 and ERK2), with a maximal level 30 min after the stimulation. The MEK1 inhibitor PD98059 reduced IGF-I-mediated p44/42 MAPKs phosphorylation and produced a parallel reduction of IGF-I-stimulated N-Myc induction. Furthermore, both alpha-IR3 and PD98059 inhibited G1-S cell cycle progression stimulated by IGF-I. Our results demonstrate that IGF-I induces N-Myc in the KP-N-RT neuroblastoma cell line at the RNA level and establishes a clear correlation between N-Myc induction and activation of p44/42 MAPK signaling.

Enzyme Inhibitors↗
PubMed2000

Neuronal differentiation in human neuroblastoma cells by nerve growth factor following TrkA up-regulation by interferon-gamma.

BACKGROUND: TrkA mRNA expression has been reported to be related to favorable outcome of neuroblastoma (NB). Previously, we found that interferon-gamma (IFN-gamma) can enhance TrkA mRNA expression in NB cell lines. In the present study, we examined the effect of nerve growth factor (NGF) on IFN-gamma-induced TrkA protein to clarify the relationship between TrkA and cell differentiation of NB. PROCEDURE: The effect of IFN-gamma on the TrkA mRNA expression was screened in six human NB cell lines and a freshly prepared sample, SK-rib, from a stage IV patient. Using two of them, we examined their morphological change during simultaneous loading of NGF and IFN-gamma. Tyrosine phosphorylation pattern after 5 min of NGF stimulation was also examined in immunoblot analysis with anti-gp140(trkA) antibody and antiphospho tyrosine antibody. RESULTS: After a 4-day treatment with 500 IU/ml IFN-gamma, TrkA mRNA increased in five cell lines and SK-rib cells in association with growth inhibition. Although the degree of morphological differentiation did not increase in proportion to the TrkA expression induced by IFN-gamma, continuous loading of both IFN-gamma and NGF caused marked morphological differentiation in a cultured KP-N-RT cell line and SK-rib cells during 10 days. Moreover, 5 min of NGF stimulation after IFN-gamma treatment caused the phosphorylation of TrkA protein and downstream proteins. CONCLUSIONS: IFN-gamma could induce the functional NGF receptor even in the aggressive phenotype of NB.

Antineoplastic Agents↗
PubMed2000

Strong immunostaining for myogenin in rhabdomyosarcoma is significantly associated with tumors of the alveolar subclass.

Rhabdomyosarcomas are a heterogeneous group of tumors with respect to their molecular basis, degree of differentiation, histology, and clinical behavior. Because of the wide variation of tumor morphology, it is often difficult to distinguish between the distinct subtypes of rhabdomyosarcomas. By using cryosections of tumor specimens and immunohistochemistry, in the present study we show that strong expression of myogenin in rhabdomyosarcoma is associated with alveolar histology (P = <0.0001, Fisher's exact test). Although staining for myogenin was observed in 22 of 26 rhabdomyosarcomas, all alveolar rhabdomyosarcomas (nine of nine) showed high levels of staining for myogenin, as defined by the frequency and intensity of staining of the tumor cells. The staining pattern suggests that the tumor cells are clonally derived from myogenin-positive progenitor cells. In contrast, most embryonal rhabdomyosarcomas (13 of 15) were either negative or showed a low level of staining for myogenin. In these tumors a larger proportion of tumor cells were distinctly negative for myogenin. Six of seven alveolar rhabdomyosarcomas that strongly stained for myogenin were also positive for Pax3-7/Forkhead (FKHR) by polymerase chain reaction/reverse transcriptase-polymerase chain reaction. One of two embryonal rhabdomyosarcomas that strongly stained for myogenin was retrospectively found to be positive for Pax3/FKHR transcripts. Quantitative analysis for myogenin by Western blotting using a smaller subset of rhabdomyosarcomas revealed that in general there was a good correlation between immunohistochemical staining and Western blotting (P = 0.01, Pearson Correlation), although the former technique was more sensitive for detecting tumors with low levels of the protein. On average, alveolar rhabdomyosarcomas expressed at least threefold more myogenin than embryonal rhabdomyosarcomas. Our data show that staining for myogenin will be a simple, rapid, and accurate adjunct for distinguishing between alveolar and embryonal rhabdomyosarcomas. We propose that embryonal rhabdomyosarcomas result from an early block in myogenesis, before the expression of myogenin. In contrast, we propose that alveolar rhabdomyosarcomas either originate from a late block in myogenesis (after expression of myogenin) or that the pathological mechanisms involved in these neoplasms also induce strong expression of this protein.

Antibodies, Monoclonal↗
PubMed2000

[Sjögren's syndrome with MALT (mucosa-associated lymphoid tissue) lymphoma in a 13-year-old girl: a case report].

We report A case of Sjögren's syndrome complicated with MALT (mucosa-associated lymphoid tissue lymphoma) in childhood. Additionally, Helicobacter pylori infection into the gastric mucosa was highly suspected in this case. A 13-year-old girl suffering from multiple joint pain had received treatment as Juvenile Rheumatic Arthritis with no clinical improvement until introduction to our hospital. On admission to our hospital, high levels of serum anti-SSA and anti-SSB (80.2 and 16.1 holds, respectively) were detected. Minor salivary gland biopsy showed a typical histological finding for Sjögren's syndrome as infiltrating lymphocytes around the excretory ducts. Computed tomography and 67Gallium scintigraphy showed a gastric tumor, and it was diagnosed as primary gastric B-cell MALT lymphoma by the histopathological findings. Additionally, Helicobacter pylori infection into the gastric mucosa was highly suspected. Recently it is emphasized that infection of Helicobacter pylori is related with gastric MALT lymphoma. There has been no reports of children who have Sjögren's syndrome associated with malignant lymphoma. Taken together, Helicobacter pylori infection superimposed with Sjögren's syndrome might accelerate clinical course in our particular case.

Adolescent↗
PubMed2000

[Ataxia telangiectasia].

Ataxia-telangiectasia(AT), an autosomal recessive disorder characterized by cerebellar degeneration, immunodeficiency, cancer predisposition and radiation sensitivity, is caused by mutations in a gene named ATM(AT, mutated), which encodes a 370 kDa serine-threonine kinase, whose catalytic domain is structurally related to the catalytic subunit of phosphatidylinositol 3-kinase(PI3K). ATM has been recently revealed to be involved in DNA damage recognition and cell cycle control in response to ionizing radiation damage. Further investigations of the multiple roles of ATM will explain other disease features, such as cerebellar degeneration in ATM in the near future. This review summarizes some of the recent research developments in ATM functions and their relationship to the clinical phenotypes of AT.

Ataxia Telangiectasia↗
PubMed1999

Malignant rhabdoid-tumor cell line showing neural and smooth-muscle-cell phenotypes.

Malignant rhabdoid tumor (MRT) is a rare and extremely aggressive malignant tumor in childhood. In this study, an MRT cell line, designated KP-MRT-NS, was established from the ascitic fluid taken from an 11-month-old girl, whose tumor had originated from the left kidney. Ultrastructural findings demonstrated the typical aggregation of whorls of intermediate filaments. Chromosome constitution was described as 46, XX, add (10)(q26)[17]/46, idem, dis (1;2)(q22;q31)[3] based on ISCN (1995) and a del (22)(q11.2) was not found in this cell line. The origin of MRT is controversial, various cellular origins having been proposed because of the phenotypic diversity of MRT. Therefore, in this study, to clarify the origin of MRT, the expressions of cytoplasmic proteins including smooth-muscle-specific proteins (alpha-smooth-muscle actin, basic calponin, smooth-muscle-myosin-heavy-chain isoforms of SM1 and SM2) in the primary-MRT tissue and cell line were analyzed. In the primary-tumor tissue, the expressions of neurofilament, vimentin and alpha-smooth-muscle actin were demonstrated by indirect immunofluorescence. In the KP-MRT-NS cell line, the expression of neurofilament, alpha-smooth-muscle actin, basic calponin and smooth-muscle-myosin heavy chain of SM1 and SM2 isoforms was revealed by immunofluorescence, Western blot and/or reverse transcriptase-polymerase chain reaction (RT-PCR). MyoD1 mRNA, determined as a skeletal-muscle-cell lineage marker, was not expressed in the primary-tumor tissue or in the KP-MRT-NS cell line. According to our findings, the MRT cells are of both neural and smooth-muscle cell phenotypes, and support the neural-crest origin of MRT.

Blotting, Western↗
PubMed1999

Rapamycin causes poorly reversible inhibition of mTOR and induces p53-independent apoptosis in human rhabdomyosarcoma cells.

The mammalian target of rapamycin (mTOR) has been shown to link growth factor signaling and posttranscriptional control of translation of proteins that are frequently involved in cell cycle progression. However, the role of this pathway in cell survival has not been demonstrated. Here, we report that rapamycin, a specific inhibitor of mTOR kinase, induces G1 cell cycle arrest and apoptosis in two rhabdomyosarcoma cell lines (Rh1 and Rh30) under conditions of autocrine cell growth. To examine the kinetics of rapamycin action, we next determined the rapamycin sensitivity of rhabdomyosarcoma cells exposed briefly (1 h) or continuously (6 days). Results demonstrate that Rh1 and Rh30 cells were equally sensitive to rapamycin-induced growth arrest and apoptosis under either condition. Apoptosis was detected between 24 and 144 h of exposure to rapamycin. Both cell lines have mutant p53; hence, rapamycin-induced apoptosis appears to be a p53-independent process. To determine whether induction of apoptosis by rapamycin was specifically due to inhibition of mTOR signaling, we engineered Rh1 and Rh30 clones to stably express a mutant form of mTOR that was resistant to rapamycin (Ser2035-->Ile; designated mTOR-rr). Rh1 and Rh30 mTOR-rr clones were highly resistant (>3000-fold) to both growth inhibition and apoptosis induced by rapamycin. These results are the first to indicate that rapamycin-induced apoptosis is mediated by inhibition of mTOR. Exogenous insulin-like growth factor (IGF)-I protected both Rh1 and Rh30 from apoptosis, without reactivating ribosomal p70 S6 kinase (p70S6K) downstream of mTOR. However, in rapamycin-treated cultures, the response to IGF-I differed between the cell lines: Rh1 cells proliferated normally, whereas Rh30 cells remained arrested in G1 phase but viable. Rapamycin is known to inhibit synthesis of specific proteins but did not inhibit synthesis or alter the levels of mTOR. To examine the rate at which the mTOR pathway recovered, the ability of IGF-I to stimulate p70S6K activity was followed in cells treated for 1 h with rapamycin and then allowed to recover in medium containing > or =100-fold excess of FK506 (to prevent rapamycin from rebinding to its cytosolic receptor FKBP-12). Our results indicate that, in Rh1 cells, rapamycin dissociates relatively slowly from FKBP-12, with a t1/2 of approximately 17.5 h. in the presence of FK506, whereas there was no recovery of p70S6K activity in the absence of this competitor. This was of interest because rapamycin was relatively unstable under conditions of cell culture having a biological t1/2 of approximately 9.9 h. These results help to explain why cells are sensitive following short exposures to rapamycin and may be useful in guiding the use of rapamycin analogues that are entering clinical trials as novel antitumor agents.

Apoptosis↗
PubMed1999

Suggestion audiometry for non-organic hearing loss (pseudohypoacusis) in children.

Pertaining to non-organic hearing loss in children, three goals should be attained: detection of this disease, determination of true hearing levels and information about the possible cause. Recently, objective tests have been used principally for children with non-organic hearing loss; however, these lack the simplicity and convenience of traditional audiometry. A new method, which is referred to as suggestion audiometry, since it is suggested to the patient that hearing will be improved as a result of the test procedure, was developed for the purpose of simultaneously achieving the above-stated three goals. The subjects were 20 patients aged 8-16 years suspected of demonstrating non-organic hearing loss and whose apparent hearing loss had been identified by school hearing examinations. Suggestion pure tone audiometry was useful for the detection of non-organic hearing loss and suggestion speech audiometry was valuable for the determination of true hearing levels. The subjects were classified into four groups according to the test results. We discuss causes of the disease based on the classification of the subjects obtained from this test procedure.

Adolescent↗
PubMed1999

Amino acid-dependent control of p70(s6k). Involvement of tRNA aminoacylation in the regulation.

In human T-lymphoblastoid cells, downstream signaling events of mammalian target of rapamycin (mTOR), including the activity of p70(s6k) and phosphorylation of eukaryotic initiation factor 4E-binding protein 1, were dependent on amino acid concentration in the culture media, whereas other growth-related protein kinases were not. Amino acid-induced p70(s6k) activation was completely inhibited by rapamycin but only partially inhibited by wortmannin. Moreover, amino acid concentration similarly affected the p70(s6k) activity, which was dependent on a rapamycin-resistant mutant (S2035I) of mTOR. These data indicate that mTOR is required for amino acid-dependent activation of p70(s6k). The mechanism by which amino acids regulate p70(s6k) activity was further explored: 1) amino acid alcohols, which inhibit aminoacylation of tRNA by their competitive binding to tRNA synthetases, suppressed p70(s6k) activity; 2) suppression of p70(s6k) by amino acid depletion was blocked by cycloheximide or puromycin, which inhibit utilization of aminoacylated tRNA in cells; and 3) in cells having a temperature-sensitive mutant of histidyl tRNA synthetase, p70(s6k) was suppressed by a transition of cells to a nonpermissible temperature, which was partially restored by addition of high concentrations of histidine. These results indicate that suppression of tRNA aminoacylation is able to inhibit p70(s6k) activity. Deacylated tRNA may be a factor negatively regulating p70(s6k).

Amino Acids↗
PubMed1999

Variable-speech-rate audiometry for hearing aid evaluation.

A new hearing aid evaluation method using variable-speech-rate audiometry (VSRA) was developed. VSRA was newly created based on the Japanese speech audiometry authorized by the Japan Audiological Society. The ordinary speech audiometry can not reveal a temporal factor in word discrimination ability of the hearing impaired. Since, with VSRA, we can compare several performance-intensity curves obtained from different speech-rate speech audiometries, the impact on the auditory system of each patient by the fast or slow speech rate could be easily determined. Taking the temporal factor of the auditory systems into consideration by using VSRA, hearing aid evaluation was performed for a master hearing aid with three types of signal processing and fitting for 36 hearing impaired subjects. Then hearing aid evaluation was performed using VSRA for a newly developed portable multi-function digital hearing aid with two types of signal processing and analog hearing aids which had been used by hearing-impaired patients. As a result, VSRA was useful for hearing aid evaluation, in particular, for cases when ordinary normal speech rate audiometry does not provide a significant difference in word discrimination scores. In addition, using VSRA revealed that amplitude compression is more effective for improvement of word discrimination than linear amplification.

Adolescent↗
PubMed1999

Development of adaptive phonetic gestures in children: evidence from vowel devoicing in two different dialects of Japanese.

High vowels between voiceless consonants are often devoiced in many languages, as well as in many dialects of Japanese. This phenomenon can be hypothesized to be a consequence of the adaptive organization of the laryngeal gestures to various conditions, including dialectal requirements. If this theory is correct, it may be possible to predict developmental changes in vowel devoicing based on the developmental improvement in the dialect-specific organization of the laryngeal gestures. To test this expectation, the developmental properties of vowel devoicing were investigated for 72 children of 4 and 5 years of age, and 37 adults in two dialects of Japanese. One was the Osaka dialect, with a low devoicing rate, and the other the Tokyo dialect, with a high devoicing rate. In the Tokyo dialect, the devoicing rate of children significantly increased and reached an adultlike level by the age of 5 years, whereas it remained low irrespective of age in Osaka. The vowel devoicing of 5-year-old children exhibited the same characteristics as that of the adults of their respective dialect. These results suggest that children growing up with the Tokyo dialect acquire the articulatory gestures which do not inhibit vowel devoicing by the age of 5 years, whereas children growing up with the Osaka dialect acquire those which inhibit the devoicing of vowels by the same age. The results fit in well with the predictions of the gestural account of vowel devoicing. It is also suggested that learning dialect-specific adaptive strategies to coordinate voicing and devoicing gestures as required to attain an adultlike vowel devoicing pattern is a long process: By the age of 5 years children have completed enough of this process to become members of their dialectal community.

Adaptation, Psychological↗
PubMed1998

Task-dependent laterality for cue decoding during spoken language processing.

The task-dependent laterality of the auditory cortices was investigated by measuring the magnetic fields elicited by three forms of a Japanese verb, which differed in terms of prosodic and phonetic cues. Significant task-dependent magnetic fields were found in both hemispheres during a prosody-related task, but only in the left during a phoneme-related task. The latency was similar to the mismatch negatively which reflects the neural activity of automatic cue decoding. These results suggest that task-dependent schemata are activated at least partially in parallel with automatic cue-decoding processes such that those in the left hemisphere process linguistic information irrespective of acoustic cues whereas those in the right hemisphere process prosodic information.

Adult↗
PubMed1998

Malignancies of human thyroid tumors and dynamic magnetic resonance imaging (MRI).

Time intensity curves for gadolinium-diethylene triaminepentacetic acid (Gd-DTPA) enhanced magnetic resonance imaging (MRI), namely dynamic MRI, were determined for thyroid diseases and compared with findings of histopathologic examination. Time intensity curves for solid lesions were determined, excluding cases with secondary changes such as calcification, hemorrhage, necrosis and fibrosis. Three different patterns of time intensity curves were observed: rapid washout, delayed washout and no change. In our previous study, malignant grades of thyroid tumors were estimated immunohistochemically by epidermal growth factor receptor (EGFR) antibody. In most of malignant diseases and a few benign diseases that had marked cell proliferative activity with staining EGFR strongly, the time intensity curve displayed a delayed washout pattern, in which intensity was above 1/2-maximal value within 10 min after injection Gd-DTPA. Almost all benign diseases and a few well differentiated carcinomas displayed a rapid washout pastern, in which intensity was decreased to lower than 1/2 of peak grade within 10 min following injection and showed staining EGFR weakly. Benign diseases showing no change of time intensity curve, did not almost show aEGFR positive cell. These findings suggested that the time intensity curve obtained from dynamic MRI might indicate differentiated grades and cell proliferating activity of thyroid tumors.

Contrast Media↗
PubMed1998

Long-term observation after soft posterior meatal wall reconstruction in ears with cholesteatoma.

We performed tympanoplasty with reconstruction of the soft posterior meatal wall for the prevention of post-operative retraction pocket formation. Our method is characterized by the reconstruction of the soft posterior meatal wall, non-obliteration with permanent or temporary materials, including Gelfoam, no use of a Palva flap and the use of fibrin glue for attaching the fascia to the posterior meatal skin. None of the patients experienced post-operative narrow-neck retraction pocket formation, and whenever aeration of the middle ear was disturbed, a balloon-like retraction was observed. Not all the posterior meatal walls retracted. The final position of the posterior meatal wall varied among the subjects. No serious cavity or hearing problems have occurred since surgery. Due to the strong possibility of post-operative retraction pocket formation in cases with a large balloon-like retraction, we rejected adopting the canal wall up technique or hard posterior meatal wall reconstruction.

Cholesteatoma, Middle Ear↗
PubMed1998

Studies on the mechanism of resistance to rapamycin in human cancer cells.

Rapamycin is a potent cytostatic agent that arrests cells in the G1 phase of the cell cycle. The relationships between cellular sensitivity to rapamycin, drug accumulation, expression of mammalian target of rapamycin (mTOR), and inhibition of growth factor activation of ribosomal p70S6 kinase (p70(S6k)) and dephosphorylation of pH acid stable protein I (eukaryotic initiation factor 4E binding protein) were examined. We show that some cell lines derived from childhood tumors are highly sensitive to growth inhibition by rapamycin, whereas others have high intrinsic resistance (>1000-fold). Accumulation and retention of [14C]rapamycin were similar in sensitive and resistant cells, with all cells examined demonstrating a stable tight binding component. Western analysis showed levels of mTOR were similar in each cell line (<2-fold variation). The activity of p70(S6k), activated downstream of mTOR, was similar in four cell lines (range, 11.75-41. 8 pmol/2 x 10(6) cells/30 min), but activity was equally inhibited in cells that were highly resistant to rapamycin-induced growth arrest. Rapamycin equally inhibited serum-induced phosphorylation of pH acid stable protein I in Rh1 (intrinsically resistant) and sensitive Rh30 cells. In serum-fasted Rh30 and Rh1 cells, the addition of serum rapidly induced c-MYC (protein) levels. Rapamycin blocked induction in Rh30 cells but not in Rh1 cells. Serum-fasted Rh30/rapa10K cells, selected for high level acquired resistance to rapamycin, showed >/=10-fold increased c-MYC compared with Rh30. These results suggest that the ability of rapamycin to inhibit c-MYC induction correlates with intrinsic sensitivity, whereas failure of rapamycin to inhibit induction or overexpression of c-MYC correlates with intrinsic and acquired resistance, respectively.

Adaptor Proteins, Signal Transducing↗