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Biomedical subjects

A Yamada

Publications and source records attributed to A Yamada.

At least 181 records · Page 10Linked to original sources
PubMed1998

JAK2 and JAK1 constitutively associate with an interleukin-5 (IL-5) receptor alpha and betac subunit, respectively, and are activated upon IL-5 stimulation.

The human interleukin-5 receptor (hIL-5R) consists of a unique alpha subunit (hIL-5Ralpha) and a common beta subunit (betac) that activate two Janus kinases (JAK1 and JAK2) and a signal transducer and activator of transcription (STAT5). The precise stoichiometry of the hIL-5R subunits and the role of JAK kinases used in IL-5 signaling were investigated. We analyzed the interaction between hIL-5Ralpha and betac by immunoprecipitation using anti-hIL-5Ralpha and anti-betac monoclonal antibodies. The binding of JAK1 and JAK2 to each hIL-5R subunit was also evaluated in the hIL-5-responsive cell line, TF-h5Ralpha. It was observed that IL-5 stimulation induced the recruitment of betac to hIL-5Ralpha, although in the absence of IL-5 the subunits remain independent. In the absence of IL-5, JAK2 and JAK1 were associated with hIL-5Ralpha and betac, respectively. IL-5 stimulation resulted in tyrosine phosphorylation of JAK2, JAK1, betac, and STAT5. Moreover, IL-5-induced dimerization of IL-5R subunits caused JAK2 activation and betac phosphorylation even in the absence of JAK1 activation. Furthermore, tyrosine phosphorylation of JAK1 was dependent on the activation of JAK2. Detailed study of the C-terminal truncated cytoplasmic domain of hIL-5Ralpha revealed that the cytoplasmic stretch at position 346-387, containing the proline-rich region, is necessary for JAK2 binding. These observations suggest that activation of hIL-5Ralpha-associated JAK2 is indispensable for the IL-5 signaling event.

Humans↗
PubMed1998

Frequent clonal expansion of peripheral T cells in patients with autoimmune diseases: a novel detecting system possibly applicable to laboratory examination.

To investigate T cell involvement in antigen-specific immune responses, it is important to detect accumulating T cells at a clonal level in vivo. However, thus far the clinical application of such analyses has been limited. Here we have established novel primers to anneal with T cell receptor (TCR) beta genes of multiple Vbeta families and applied them to reverse transcription-polymerase chain reaction-single strand conformation polymorphism (RT-PCR-SSCP) analysis to evaluate peripheral T cell clonality of autoimmune disease patients. As a result, the new Vbeta primers could detect accumulating T cell clones in the periphery of healthy individuals and patients. It was revealed that patients with autoimmune diseases such as systemic lupus erythematosus (SLE) had a larger number of clonal accumulations of peripheral T cells compared with normal individuals. Thus, the RT-PCR-SSCP system using the new multifamily Vbeta primers is the first such laboratory examination to detect T cell clonal expansion, and will provide a simple and sensitive tool to aid in the diagnosis and also in the investigation of the pathogenesis of autoimmune diseases.

Adult↗
PubMed1998

Immunohistochemical analysis of clinically transplanted muscles.

BACKGROUND: Although a number of studies have examined the morphology and function of experimentally transplanted muscles, immunohistochemical evaluation of clinically transplanted muscles has not been reported. The purpose of this study was to examine clinically transplanted muscles at long periods after transplantation with biochemical markers specific for satellite cell activation and muscle regeneration. MATERIALS AND METHODS: Nine biopsies of muscles transplanted to the paralyzed face were examined. In five cases, the gracilis muscles were transplanted about 1 year after cross face nerve grafting. The other four cases underwent one-stage latissimus dorsi (LD) muscle transplantation. Twelve to 162 months after transplantation, muscle biopsies were harvested in nine cases. In eight cases, secondary corrections of facial expression including debulking of the grafted muscle were required, while another muscle was transplanted in one case because of the failed first operation. As control, six specimens of normal LDs were examined as well. Monoclonal antibodies were employed to visualize myosin heavy chain (MHC) isoforms (slow, fast, and embryonic) and MyoD protein. RESULTS: Although one specimen exhibited only small, atrophic fibers indicating failed reinnervation, the remaining eight specimens showed regularly distributed fibers and type grouping indicating successful reinnervation. There was no statistically significant difference in fiber area and lesser diameter between normal LDs and transplanted LDs. However, even in these successfully reinnervated muscles, intermediate and small fibers expressing embryonic MHC and small cells expressing MyoD were observed, suggesting that satellite cells were activated for repair of the adjacent fibers. CONCLUSIONS: Muscle adaptation (presumably to denervation), which is a regenerative change accompanied by activation of satellite cells, was still seen even long periods after transplantation. It is concluded that, in microneurovascular human skeletal muscle transfers, there is a wide variation in the time required for reinnervation of individual muscle fibers, and it may be that human muscle fibers cannot be properly reinnervated after denervation has continued for a certain period such as 12 months.

Adult↗
PubMed1998

Fluctuation correlation in the sliding movement generated by protein motors in vitro.

The fluctuation in the sliding distance of cytoskeletal filaments driven to move by protein motors in vitro does not depend on the filament length. This is in sharp contrast to the case of Brownian movement of filamentous particles in their longitudinal directions, in which the positional fluctuation is proportional to the inverse of the length (L) of filaments. This latter 1/L dependence is a direct consequence of the central limit theorem: the statistical independence and randomness of the solvent molecule collisions with filaments, the collisions of which cause the random Brownian movement. The above length-independence in the sliding distance fluctuation found in the in vitro motility indicates the presence of correlation in the fluctuation. A possible explanation for the correlation is to assume that there is an extended time-correlation in the sliding movement, a correlation which could be produced by the actions on a sliding filament of protein motors with their heads randomly oriented in the in vitro motility assay system. We have checked this possibility by using long myosin thick filaments of molluscan smooth muscles, on which myosin heads are uniformly oriented, and have found that even with such myosin filaments with oriented myosin heads, the positional fluctuation of actin sliding distance does not depend on the actin filament length. This result thus indicates that the actions of protein motors on a sliding filament are not statistically independent or random, so that the positional fluctuation of filaments in the motor-generated sliding movement does not depend on the filament length.

Actins↗
PubMed1998

A novel glycoprotein obtained from Chlorella vulgaris strain CK22 shows antimetastatic immunopotentiation.

A glycoprotein extract (CVS), derived from the unicellular green alga Chlorella vulgaris, strain CK22, exhibited a pronounced antitumor effect against both spontaneous and experimentally induced metastasis in mice. Inhibition of tumor metastasis was enhanced when intratumor administration of CVS was followed by s.c. injection of CVS. Anti-metastatic immunopotentiation was observed in euthymic mice, but not in athymic nude mice. The antitumor activity of CVS was reflected in antigen-specific, T-cell-mediated immunity. Both CD4 and CD8 T cells contributed to the antimetastatic effects, as shown by in vivo depletion experiments with anti-T-cell subset antibodies. Furthermore, CVS caused the recruitment of T cells to the regional lymph nodes and their proliferation in these organs. The CD4-positive population, following CVS injection at the time of tumor rechallenge, displayed a pronounced increase in the proportion of T cells that were CD18 bright, CD44 bright, CD25+, CD54+, CD69+ or CD71+ in the lymph nodes. Thus, CVS induces T cell activation in peripheral lymph nodes in tumor-bearing mice. We conclude that CVS augments antimetastatic immunity through T cell activation in lymphoid organs and enhances recruitment of these cells to the tumor sites. Presurgical treatment with CVS might prevent metastasis or tumor progression.

Animals↗
PubMed1998

Typus melancholicus in light of the five-factor model of personality.

The present paper examines Typus melancholicus (TM), which is widely accepted as premorbid personality of depression in Germany and Japan, from the view-point of the five-factor model of personality, which has recently been gaining international popularity as the comprehensive model of personality traits. Two measures of TM, von Zerssen's F-list and Kasahara's scale, as well as the personality questionnaire for the five-factor model, NEO Five Factor Inventory, were completed for 140 consecutive psychiatric outpatients by their close relatives. It was found that (a) the two measures of TM had good internal consistency reliability, (b) they had reasonable concurrent validity, and (c) TM was characterized by high Conscientiousness, high Agreeableness and, to a lesser degree, high Extraversion. The results were largely in agreement with theoretical prediction and provide further support to the construct validity of the TM measures. Whether combining the three personality traits into one type is meaningful in depicting a particular premorbid personality constellation awaits further empirical examination.

Adult↗
PubMed1998

Effects of ruthenium red on membrane ionic currents in urinary bladder smooth muscle cells of the guinea-pig.

Three major ionic currents, Ca2+-dependent K+ current (IK-Ca), delayed rectifier type K+ current (Ikd) and Ca2+ current (ICa), were activated by depolarization under whole-cell clamp in single smooth muscle cells isolated from guinea-pig urinary bladder. Externally applied ruthenium red (RuR) reduced the amplitude of IK-Ca and ICa at 0 mV (IC50 values were 4.2 and 5.6 muM, respectively), but did not affect IKd. Spontaneous transient outward currents (STOCs) and caffeine-induced outward currents (Icaf) at -30 mV were reduced by external 10 muM RuR. When 10 muM RuR was added to the pipette solution, IK-Ca during depolarization, STOCs and Icaf significantly decreased with time. RuR did not change the unitary current amplitude of the large-conductance Ca2+-dependent K+ (BK) channels, but reduced the open probability of the channel under excised patch-clamp recording mode. RuR reduced the channel activity more effectively from the cytosolic face than from the other. This inhibition decreased when the cytosolic Ca2+ concentration was increased. These results indicate that RuR blocks BK and Ca2+ channels in urinary bladder smooth muscle cells. The decrease in IK-Ca, STOCs and Icaf by RuR is attributable to the direct inhibition of BK channel activity, probably in addition to the inhibition of Ca2+ release from storage sites. The direct inhibition of BK channel activity by RuR may be related to the interaction of RuR with the Ca2+-binding sites of the channel protein.

Animals↗
PubMed1998

Dumbbell type jugular foramen meningioma extending both into the posterior cranial fossa and into the parapharyngeal space: report of 2 cases with vascular reconstruction.

Two cases with huge dumbbell type jugular foramen meningioma with extension into the parapharyngeal space are reported. A well co-ordinated surgical strategy for total resection to this high risk tumour with neurosurgeons, otolaryngologists and plastic surgeons is mandatory to minimise operative complications. Both of our patients presented with a cervical mass and lower cranial nerve palsies, and had huge dumbbell type masses extending from the posterior cranial fossa through the jugular foramen to the parapharyngeal space, encasing the cervical internal carotid artery. Gross total resection of the tumours was successfully achieved by basically a 2-stage operation. In the first stage, posterior fossa tumours were removed by the transjugular approach, combined with the petrosal approach in one case. In the second stage, cervical tumours were removed along with the cervical carotid artery by the transcervical and/or transmandibular approach, followed by vascular reconstruction from the ipsilateral carotid artery to the middle cerebral artery using saphenous vein graft. From these experiences, we recommend this 2-stage operation for large dumbbell type meningiomas extending to the infratemporal/parapharyngeal space. The intracranial tumour is removed at the first operation. The extracranial portion is resected at the second, and if necessary, the involved cervical carotid artery is resected and simultaneous revascularisation using saphenous vein graft is performed with a vascularised free muscle graft. This strategy could maximise the functional preservation on the one hand, and minimise the surgical risk, such as postoperative infection, on the other.

Adult↗
PubMed1998

Safety evaluation of Nostoc flagelliforme (nostocales, Cyanophyceae) as a potential food.

The safety of the alga genus Nostoc flagelliforme Born. etFlah. as a human food source was evaluated in an oral acute toxicity study and in a 28-day oral subacute toxicity study using rats. In the acute toxicity study, the dried powder of N. flagelliforme was orally administered to male and female rats at a dose of 1250 mg/kg and 2500 mg/kg. Neither mortality nor changes in general condition were observed in either the study groups or the control group over a 14-day observation period. In the subacute toxicity study, N. flagelliforme powder was administered orally to male and female rats at a dose of 500 mg/kg and 1000 mg/kg for a period of 28 days. Neither mortality nor changes in general condition were observed in either the treatment group or the control group throughout the 28-day administration period. No reduction in food consumption or body weight gain was observed in the experimental animals. Ophthalmological tests performed at the end of the administration period revealed no abnormalities within the ophthalmological parameters. In the haematological tests and serum biochemical tests performed at the time of completion of the administration period, no adverse effects of N. flagelliforme were observed. At autopsy, organ weight at the end of the experimental period and histopathological tests of specimens obtained from the autopsied animals revealed no significant influences of N. flagelliforme. In conclusion, considering the absence of adverse effects of N. flagelliforme in this study, findings in the oral acute toxicity study and the 28-day oral subacute toxicity study may indicate the safety of N. flagelliforme for human consumption. This study is in agreement with the novel nutraceutical idea "Phycophagism".

Animals↗
PubMed1998

Apa I polymorphism in the vitamin D receptor gene may affect the parathyroid response in Japanese with end-stage renal disease.

Vitamin D [1,25(OH)2D3] plays a key role in the pathogenesis of secondary hyperparathyroidism. A polymorphism in the vitamin D receptor (VDR) gene is reported to be involved in bone mineral density and the serum level of intact-osteocalcin (i-OC) in patients with osteoporosis. We investigated the relationship between VDR gene polymorphisms and the levels of intact PTH (i-PTH) and i-OC in 129 Japanese patients with end-stage renal disease (ESRD). The VDR gene sequences were PCR-amplified, and the product was cleaved with the restriction enzymes Bsm I and Apa I. Undigested alleles were designated as B and A, and the digested alleles as b and a, respectively. The frequencies for the Bsm I polymorphism were 0.0% BB, 19.4% Bb, and 80.6% bb, while those for Apa I polymorphism were 14.2% AA, 47.2% Aa, and 38.6% aa. The Bsm I polymorphism of VDR was greatly biased in Japanese people. The i-PTH level in the aa group was about twice as high as those in the both AA group and Aa group (P < or = 0.04). The i-OC concentrations in the aa group was also approximately double those in both the AA group and Aa group (P < or = 0.03). In contrast, no significant differences in age, duration of dialysis, male/female ratio, or the incidence of diabetic nephropathy were observed among these three groups. On the other hand, there was no significant differences in i-PTH and i-OC between the Bb and bb groups. These results suggest that VDR gene polymorphisms can affect parathyroid response in ESRD patients, and the Apa I polymorphism is more informative in Japanese patients than the Bsm I polymorphism. The VDR a gene allele may define the pathogenesis of secondary hyperparathyroidism and of high turnover bone disease in patients with ESRD.

Alleles↗
PubMed1998

A newly developed on-line monitoring system for the determination of serum electrolytes and urea during hemodialysis.

Continuous monitoring of serum solute concentrations throughout a dialysis session could be beneficial for the prevention of intradialytic morbidity such as hypotension and for the confirmation of dialysis adequacy. In this paper, we introduce a new on-line monitoring system for use during hemodialysis sessions, a system developed for the continuous observation of serum biochemical data. Using this system, we also show the possibility of clinical applications. Intradialytic hypotension could be prevented by the observation of filtrate sodium concentration and the control of dialysate sodium concentration. The termination of a dialysis session could be decided by the observation of the filtrate urea nitrogen, on the basis of the Kt/V urea ratio. Because monitoring for other solutes such as calcium and creatinine is theoretically available, clinical applications will continue to increase in the future.

Adult↗
PubMed1998

Reconstruction of skull defects with vascularized omentum transfer and split calvarial bone graft: two case reports.

Autogenous calvarial bone grafts have been widely used in craniofacial reconstruction following trauma, congenital anomalies, and head and neck tumors. In cases of late restoration of a collapsed cranial vault, an extradural dead space is occasionally observed which might cause infection and grafted bone absorption. The combined use of a split calvarial bone graft and an omental flap has been an effective technique for treating complicated cranial defects. The omental flap eliminates the extradural dead space between the grafted calvarial bone and the scarred dura, and provides an acceptable vascular bed for grafted bone. The authors report this technique for complex cranioplasties in two cases, with good cosmetic results.

Aged↗
PubMed1998

Direct observation of a central bare zone in a native thick filament isolated from the anterior byssus retractor muscle of Mytilus edulis using fluorescent ATP analogue.

To investigate the existence of a central bare zone in native thick filaments isolated from the anterior byssus retractor muscle (ABRM) of blue mussels (Mytilus edulis), the filaments were observed by fluorescence and dark-field microscopy after being incubated in the presence of Ca2+ with the fluorescent ATP analogue, Cy3-EDA-ATP. Filaments appeared under dark-field illumination as thin rods with tapered ends of length 5-30 microm. Fluorescence microscopy revealed that Cy3-EDA-ATP was bound to these filaments, except near their center. Although the boundary between this central non-fluorescent zone and fluorescent regions was not clearly defined, there was a trend for the width of the central non-fluorescent zone to increase with thick filament length (correlation coefficient = 0.45; n = 142). When Cy3-EDA-nucleotides bound to thick filaments were displaced by excess ATP, fluorescent images disappeared with a rate constant of 0. 024 s-1, close to the turnover rate of Cy3-EDA-ATP by myosin on the native thick filaments. These results indicate that each native thick filament isolated from the ABRM has a central bare zone, but its boundary was not sharply resolved.

Adenosine Triphosphate↗
PubMed1998

Immediate free flap reconstruction for head and neck pediatric malignancies.

We performed six immediate free flap reconstructions after tumor ablation in 5 children under the age of 15 years presenting with head and neck malignancy. One patient underwent free flap transfer on two separate occasions because of tumor recurrence. There were no flap losses nor were there any complications related to microvascular surgery. Although a pediatric head and neck malignant tumor is rare, surgical resection is the primary therapeutic role for those that are amenable to complete excision. Pediatric microsurgery provides a safe and reliable procedure for reconstruction of head and neck defects after extirpation of the tumor.

Adolescent↗
PubMed1998

Complications of craniofacial surgery for tumors involving the anterior cranial base.

OBJECTIVE: To evaluate the risk factors for postoperative complications among patients undergoing craniofacial resection for the treatment of anterior cranial base tumors, a retrospective analysis of patients treated in University of Tokyo Hospital between September 1987 and November 1996 was conducted. METHODS: Twenty-nine patients underwent 33 craniofacial resections for tumors involving the anterior cranial base. Twenty-three of the 29 patients had malignant tumors and 6 patients had benign tumors. Anterior craniofacial resection was performed using a combination of intracranial and extracranial approaches. Radiotherapy and neoadjuvant chemotherapy were administrated to some patients. RESULTS: Severe intracranial infections were more common among patients who underwent partial frontal lobectomies (P < 0.03). These infections occurred only in patients who had been treated previously with a craniotomy (P < 0.02) and a total radiation dose of > or =60 Gy (P = 0.06). Neither management of the extracranial structures nor methods of reconstruction of the cranial base showed significant correlation with major postoperative complications. CONCLUSION: Compared with previous reports, craniofacial resection has become a relatively safe and effective procedure for the treatment of tumors involving the anterior cranial base. However, additional care should be taken with patients who have experienced a previous craniotomy, frontal lobe involvement, or radiotherapy with a total dose of > or =60 Gy.

Adolescent↗