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Biomedical subjects

K Yamada

Publications and source records attributed to K Yamada.

At least 91 records · Page 5Linked to original sources
PubMed2004

Expression of epiregulin and amphiregulin in the rat ovary.

We have previously reported that the epidermal growth factor (EGF) family growth factor, epiregulin, is expressed in rat ovarian granulosa cells by induction with pregnant mare serum gonadotropin (PMSG). In this study, we report that amphiregulin, another member of the EGF family, was also induced in the rat ovary by gonadotropin treatment. Northern blot analysis revealed that PMSG treatment induced the expression of both epiregulin and amphiregulin mRNA after 24 h, but the expression then decreased 48 h after treatment. Further treatment with human chorionic gonadotropin (hCG) rapidly induced the expression of both epiregulin and amphiregulin genes and maximal levels were reached 4 h after hCG treatment. A marginal increase in amphiregulin mRNA levels was also observed 6 h after PMSG treatment. In situ hybridization revealed that epiregulin and amphiregulin mRNAs were localized in the granulosa cells of large antral follicles. These spatio-temporal expression patterns were similar to those of cyclo-oxygenase-2 (COX-2) and progesterone receptor (PR). In adult cycling rats, epiregulin and amphiregulin were strongly induced at 1800 and 2000 h on proestrus coinciding with the preovulatory LH surge. An in situ hybridization study also showed that epiregulin and amphiregulin mRNAs were detectable in the granulosa cells of preovulatory ovarian follicles at 2000 h on proestrus, where transcripts of COX-2 and PR were co-localized with those of epiregulin and amphiregulin. These observations suggested that the EGF family members, epiregulin and amphiregulin, may play a role in the ovulatory process of cycling rats as well as in the induction of ovulation in immature rats.

Amphiregulin↗
PubMed2004

[Successful staged repair of a symptomatic neonate of tetralogy of Fallot with severe absent pulmonary valve syndrome].

Tetralogy of Fallot with absent pulmonary valve has been classified to a few groups. The most severe one is characterized by symptomatic onset immediately after birth. The others are no or slightly symptomatic at least during their neonatal period. In a severely symptomatic 12-day-old neonate of tetralogy of Fallot with absent pulmonary valve who had required intubation immediately after birth, tight pulmonary banding and left side modified Blalock-Taussig shunt were performed on emergency basis. Consequently, prior massive pulmonary regurgitation was decreased significantly. Forty-five days after this first stage operation, he weaned from respiratory management. At 1-year-old, radical repair based on conotruncal repair, which consisted of patch closure of ventricular septal defect preserving the tricuspid septal leaflet function, resection of anterior wall of enlarged left pulmonary artery, and right ventricular outflow tract reconstruction using autologous tissue and a pericardial patch was performed. Bicuspid pulmonary valve, posterior one of procured autologous pulmonary wall and anterior one of polytetrafluoroethylene (PTFE) respectively, was created to minimize deterioration of the pulmonary insufficiency. Although postoperative cardiac function was kept feasible showing his central venous pressure of 7 mmHg in the main, postoperative general course was eventful especially regarding the respiratory function. The patient was weaned from the prolonged ventilator management 5 months after this radical repair eventually. Generally, to diminish the massive pulmonary regurgitation in early lifetime period could reduce a progressive airway obstruction and minimize pulmonary tissue damage. However, even after the total correction in this case, considerable peripheral segmental pulmonary obstructive lesions were persistent according to the perfusion lung scanning with 99mTc macroaggregated albumin and 99mTechnegas ventilation lung scanning studies. This persistent, supposed to be innate, pulmonary obstructive lesions might prevent ordinal recovery after cardiac radical repair for this most severe subtype of absent pulmonary valve syndrome.

Blood Vessel Prosthesis Implantation↗
PubMed2004

[Schizophrenia and ocular misalignment: phenotypic and genetic association analysis].

The increased incidence of minor physical anomalies (MPAs) in schizophrenia is the fundamental basis for the neurodevelopmental hypothesis of schizophrenia etiology. Ocular misalignment falls into the category of MPAs, but this phenotype has not been assessed in schizophrenia. This study reveals that constant exotropia displays marked association with schizophrenia. To assess the genetic mechanisms, we examined the transcription factor genes ARIX and its paralogue, PMX2B. We identified frequent deletion/insertion polymorphisms in the 20-alanine homopolymer stretch of PMX2B, with a modest association between these functional polymorphisms and constant exotropia in schizophrenia. The polymorphisms were also associated with overall schizophrenia and more specifically with schizophrenia manifesting strabismus. These results suggest a possible interaction between PMX2B and other schizophrenia-precipitating factors, increasing the risk of the combined phenotypes. This study also highlights the unique nature of the polyalanine length variations found in PMX2B.

Exotropia↗
PubMed2003

Fermi-liquid ground state in the n-type Pr(0.91)LaCe(0.09)CuO(4-y) copper-oxide superconductor.

We report nuclear magnetic resonance studies on the low-doped n-type copper-oxide Pr(0.91)LaCe(0.09)CuO(4-y) (T(c)=24 K) in the superconducting state and in the normal state uncovered by the application of a strong magnetic field. We find that when the superconductivity is removed the underlying ground state is the Fermi liquid state. This result is at variance with that inferred from previous thermal conductivity measurement and appears to contrast with that in p-type copper oxides with a similar doping level where high-T(c) superconductivity sets in within the pseudogap phase. The data in the superconducting state are consistent with the line-node gap model.

Journal Article↗
PubMed2003

Commensurate spin dynamics in the superconducting state of an electron-doped cuprate superconductor.

We report neutron scattering studies on two single crystal samples of the electron-doped (n-type) superconducting (SC) cuprate Nd2-xCexCuO4 (x=0.15) with T(c)=18 and 25 K. Unlike the hole-doped (p-type) SC cuprates, where incommensurate magnetic fluctuations commonly exist, the n-type cuprate shows commensurate magnetic fluctuations at the tetragonal (1/2 1/2 0) reciprocal points both in the SC and in the normal state. A spin gap opens up when the n-type cuprate becomes SC, as in the optimally doped p-type La2-xSrxCuO4. The gap energy, however, increases gradually up to about 4 meV as T decreases from T(c) to 2 K, which contrasts with the spin pseudogap behavior with a T-independent gap energy in the SC state of p-type cuprates.

Journal Article↗
PubMed2003

Phase diagram of La2-xSrxCuO4 probed in the infared: imprints of charge stripe excitations.

While there is increasing evidence for antiferromagnetic (AF) ordering in the Cu-O planes of high-T(c) superconductors, either static or fluctuating, there is no direct evidence so far for the charge stripes that should separate the AF domains. By investigating the optical response of La2-xSrxCuO4 for 0<or=x<or=0.26 and 30<or=T<or=295 K, we identify strong far infrared peaks whose energy, width, and intensity are consistent with a scenario of charge stripe dynamics in the Cu-O planes.

Journal Article↗
PubMed2003

Nontraumatic spinal subdural haematoma occurring in a postpartum period.

Spontaneous occurrence of spinal subdural haematoma (SSH) is very rare. While many neurological disorders can develop in pregnant patients in relation to haemostatic imbalance, there have been no reports in the literature suggesting that pregnancy and/or childbirth per se could be a single risk factor for acute SSH.A 38-year-old previously healthy woman gave birth to a baby via transvaginal normal delivery. The patient had no history of receiving anticoagulants. Eight days after delivery, she experienced sudden onset severe interscapular back pain, and the next day she developed dysesthesia in the both legs and mild urinary retention. Severe meningeal signs were noted. Lumbar puncture revealed bloody cerebrospinal fluid. Magnetic resonance images revealed SSH in the ventral position spreading from levels Th1 to Th7. The patient underwent conservative treatment after which the symptoms gradually improved. Serial MRI study at 17 and 69 days after onset showed spontaneous regression of the SSH. Spinal angiography did not show any vascular malformations, but simultaneous cerebral angiography revealed a co-existing cerebral aneurysm on the C2 segment of the left internal carotid artery. It is unlikely that the cerebral aneurysm was the origin of the SSH, based on the clinical and radiographic findings. Moreover, we confirmed the unruptured nature of the aneurysm during the clipping procedure at open surgery. We report the unique case of subacute SSH occurring 8 days after childbirth without other known risk factors. The possible etiology and magnetic resonance imaging (MRI) findings in this case, and the current controversy concerning therapy for SSH are discussed.

Adult↗
PubMed2003

Pulmonary fibrosis and lung cancer: risk and benefit analysis of pulmonary resection.

OBJECTIVE: Pulmonary fibrosis is associated with an increased risk of lung cancer and outcome of surgical resection in this setting is unknown. METHODS: We studied 22 patients (24 operations) with pulmonary fibrosis and non-small cell lung cancer treated between 1991 and 2000 (study group) and compared outcome with 951 other patients (964 operations) treated for non-small cell lung cancer over the same period (control patients). RESULTS: The two groups did not differ significantly in age (68 vs 65 years), smoking history (86% vs 95% smokers), forced expiratory volume in 1 second (2.5 L/min vs 2.3 L/min) or forced vital capacity (3.2 L vs 3.7 L), but patients with pulmonary fibrosis were more likely to be male (72% vs 58%, P <.05). The operative mortality was higher in patients with pulmonary fibrosis than in control patients (17% vs 3.1%, P <.01) and there was a higher procedure-specific mortality in pulmonary fibrosis for pneumonectomy (33% vs 5.1%, P <.01) and lobectomy (12% vs 2.6%, P <.01). Patients with pulmonary fibrosis had a higher incidence of postoperative lung injury, (21% vs 3.7%, P <.01) and a longer mean hospital stay (17 vs 9 days, P <.05). In patients with pulmonary fibrosis, the actuarial 3-year survival was 54%. There were 11 deaths in the study group, 4 postoperatively (all acute respiratory distress syndrome) and 7 late deaths (metastatic disease, n = 2; progressive pulmonary fibrosis, n = 5). Median follow-up (to death or last review) was 13 months (range, 0-120 months). Five patients developed postoperative acute respiratory distress syndrome and in 4 of these patients this proved to be fatal. Postoperative acute respiratory distress syndrome was associated with lower preoperative total lung carbon monoxide diffusion capacity (median, 58% vs 70%, P =.03) and lower preoperative carbon monoxide diffusion capacity corrected for alveolar volume (median, 48% vs 58%, P =.05) and a higher preoperative composite physiological index (median, 44 vs 33, P =.008). None of the preoperative lung function parameters or operative finding were predictors of late death. CONCLUSION: Patients with pulmonary fibrosis undergoing pulmonary resection for non-small cell lung cancer have increased postoperative morbidity and mortality, but an important subgroup has a good long-term outcome. Postoperative acute respiratory distress syndrome is associated with low preoperative gas transfer and a high composite physiological index. Resection of non-small cell lung cancer is appropriate in pulmonary fibrosis, provided that the level of functional impairment is carefully factored into patient selection.

Aged↗
PubMed2003

Immunocytochemical evidence that amyloid beta (1-42) impairs endogenous antioxidant systems in vivo.

Amyloid beta, the major constituent of the senile plaques in the brains of patients with Alzheimer's disease, is cytotoxic to neurons and has a central role in the pathogenesis of the disease. We have previously demonstrated that potent antioxidants idebenone and alpha-tocopherol prevent learning and memory impairment in rats which received a continuous intracerebroventricular infusion of amyloid beta, suggesting a role for oxidative stress in amyloid beta-induced learning and memory impairment. To test the hypothesis, in the present study, we investigated alterations in the immunoreactivity of endogenous antioxidant systems such as mitochondrial Mn-superoxide dismutase, glutathione, glutathione peroxidase and glutathione-S-transferase following the continuous intracerebroventricular infusion of amyloid beta for 2 weeks. The infusion of amyloid beta (1-42) resulted in a significant reduction of the immunoreactivity of these antioxidant substances in such brain areas as the hippocampus, parietal cortex, piriform cortex, substantia nigra and thalamus although the same treatment with amyloid beta (40-1) had little effect. The alterations induced by amyloid beta (1-42) were not uniform, but rather specific for each immunoreactive substance in a brain region-dependent manner. These results demonstrate a cytological effect of oxidative stress induced by amyloid beta (1-42) infusion. Furthermore, our findings may indicate a heterogeneous susceptibility to the oxidative stress produced by amyloid beta.

Amyloid beta-Peptides↗
PubMed2003

Polymorphisms of sorbitol dehydrogenase (SDH) gene and susceptibility to diabetic retinopathy.

The polyol pathway consists of two enzymes aldose reductase (AR) and sorbitol dehydrogenase (SDH); the former is the first enzyme in the polyol pathway, that catalyzes the reduction of glucose to sorbitol, the latter is the second one, that converts sorbitol to fructose using by NAD(+) as a cofactor. We along with others have recently found that SDH activity, the second step in the polyol pathway, might make a greater contribution to the etiology of diabetic retinopathy than does the first step involving AR. In this paper, we propose a novel hypothesis that polymorphisms of SDH gene may be correlated with SDH gene expression levels in diabetic retinas, thus being a valuable genetic marker for diabetic retinopathy.

Aldehyde Reductase↗
PubMed2003

A Japanese family with FEOM1-linked congenital fibrosis of the extraocular muscles type 1 associated with spinal canal stenosis and refinement of the FEOM1 critical region.

We identified a Japanese family with congenital fibrosis of the extraocular muscles, including 24 affected individuals through five generations. To determine their form of congenital fibrosis of the extraocular muscles, we performed clinical and linkage studies. DNA typing for linkage to the FEOM1 (12p11.2-q12) and FEOM3 (16qter) loci was performed on genomic DNA, using fluorescent microsatellite polymorphic markers. All affected individuals shared the common manifestations of congenital fibrosis of the extraocular muscles type 1 including congenital ptosis, infraducted globe position in primary gaze, and upward gaze palsy in both eyes. Unexpectedly, we found apparent spinal canal stenosis in the cervical spine in all affected family members who were examined. Genetic analysis revealed linkage to the FEOM1 locus with a maximum lod score of 4.42 at theta of zero. One affected family member harbored a recombination event between D12S345 and D12S1692, narrowing the FEOM1 locus from the published 3-cM region flanked by D12S1584 and D12S1668 to a 2.1-cM region flanked by D12S345 and D12S1668. Thus, we have established that this family segregates congenital fibrosis of the extraocular muscles type 1 as an autosomal dominant trait and that their disorder both maps to and refines the FEOM1 locus. This is the first clinical and genetic report of such a family in the Japanese population and the first report of spinal involvement in congenital fibrosis of the extraocular muscles.

Adolescent↗
PubMed2003

Recognition of left ventricular hypertrophy in new recruits of professional sumo wrestling.

The efficacy of electrocardiography (ECG) in the diagnosis of left ventricular (LV) hypertrophy in 890 males, newly recruited to Japanese professional sumo wrestling (15.9 +/- 1.8 years of age, 177.8 +/- 4.7cm, 107.3 +/- 4.7kg), was tested by comparing simple, widely employed ECG criteria (Sokolow-Lyon chest and limb lead voltages and Cornell voltage with repolarisation criteria) with echocardiographic evaluations of LV mass indexed to body surface area. LV hypertrophy was defined as a LV mass index > 2 SD above the mean value obtained from 115 age-matched, normotensive, sedentary, male controls. The prevalence of LV hypertrophy as determined by echocardiography was 9.0% the entire group and was 8.3% among the 484 normotensives. The sensitivities of the three ECG criteria were < or = 36.0%, and their specificities were 70.0-99.0%. In contrast to the Sokolow-Lyon chest lead criteria, the diagnostic performance of the Cornell criteria was little affected by body mass index (BMI), and stepwise regression revealed that BMI did not significantly correlate with Cornell voltage. Still, the diagnostic efficacy of ECG was not sufficient to merit its use for primary recognition of LV hypertrophy among professional sumo wrestlers. Indeed, LV hypertrophy will likely go undetected by ECG in most overweight muscular athletes.

Adolescent↗
PubMed2003

Conformation of the transmembrane domains in peripheral myelin protein 22. Part 1. Solution-phase synthesis and circular dichroism study of protected 17-residue partial peptides in the first putative transmembrane domain.

Charcot-Marie-Tooth disease (CMT) is the most commonly inherited peripheral neuropathy. DNA duplication and point mutation of the gene encoding peripheral myelin protein 22 (PMP22) have been found in CMT type 1A dominants. To investigate the influence of the point mutation of PMP22 on the secondary structure, protected partial peptides in the putative first transmembrane domain, wild type Boc-IVLH(Bom)VAVLVLLFVSTIV-OMe (1) and its Pro16 mutant Boc-IVLH(Bom)VAVPVLLFVSTIV-OMe (2) were synthesized. Circular dichorism (CD)-spectral analysis suggested that peptide 1 adopts a stable alpha-helical conformation in membrane-mimetic solvent,1-BuOH/1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) system. On the contrary, the mutant 2 favors beta-sheet conformation in the same solvent system. Interestingly, alpha-helix to beta-sheet transition of 2 was observed at higher contents of 1-BuOH than 70%.

Amino Acid Sequence↗
PubMed2003

Costimulatory signals distinctively affect CD20- and B-cell-antigen-receptor-mediated apoptosis in Burkitt's lymphoma/leukemia cells.

CD20 is a B-cell differentiation antigen and known to induce apoptosis in Burkitt's lymphoma/leukemia (BL) cells upon antibody-mediated crosslinking. We examined the biological effect of CD20 crosslinking on BL cell lines and observed that apoptosis induction is accompanied by activation of multiple caspases, including caspase-8, -9, -3, -2, and -7. Further investigation revealed a clear synergism between apoptosis mediated by CD20 and by B-cell antigen receptor (BCR). Examination of the effect of simultaneous crosslinking of other cell surface molecules with crosslinking of CD20 or BCR on apoptosis induction showed that these molecules had either a synergistic or inhibitory effect on induction of apoptosis. It is worth noting that some molecules had a different effect on CD20- and BCR-mediated apoptosis. Simultaneous crosslinking of the molecules CD10, CD22, CD72, and CD80 inhibited BCR-mediated apoptosis, but enhanced CD20-mediated apoptosis. Further studies revealed that regulation of CD20-induced apoptosis by other costimulatory molecules is achieved by modification of caspase activation. CD20-mediated apoptosis in BL cells may provide not only a model for understanding the mechanism regulating clonal selection of B cells but a new therapeutic strategy for BL patients.

Annexin A5↗