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Biomedical subjects

H Yamada

Publications and source records attributed to H Yamada.

At least 163 records · Page 9Linked to original sources
PubMed2001

Expression of dystroglycan complex in satellite cells of dorsal root ganglia.

In Schwann cells, the transmembrane glycoprotein beta-dystroglycan composes the dystroglycan complex together with the extracellular glycoprotein alpha-dystroglycan, which binds laminin-2 (alpha2/beta1/gamma1), a major component of the Schwann cell basal lamina. In the Schwann cell cytoplasm, beta-dystroglycan is anchored to a dystrophin isoform, Dp116. In this study, we investigated the expression of beta-dystroglycan, Dp116 and the laminin-alpha2 chain in satellite cells of rat dorsal root ganglia (DRGs). Immunohistochemical study showed that immunoreactivities for beta-dystroglycan and Dp116 were both localized to the outer rim of neuron-satellite cell and axon-Schwann cell units, indicating that both satellite and Schwann cells expressed these proteins in DRGs. Immunoreactivity for the laminin-alpha2 chain was detected in a similar location, indicating that the basal lamina surrounding satellite and Schwann cells in DRGs contained laminin-2. Ultrastructurally, immunoreactivity for the cytoplasmic domain of beta-dystroglycan as well as that for Dp116 was most intense in the cytoplasm just underlying the outer membrane of satellite cells. The immunoreactivity for laminin was associated with the outer surface of those cells, suggesting that it was localized in the surrounding basal lamina. These results indicate that the dystroglycan complex is expressed in the satellite cell outer membrane and involved in the adhesion with the basal lamina through the interaction with laminin-2.

Animals↗
PubMed2001

Esophageal smooth muscle tumor in a 25-year-old woman with congenital malformations.

We recently treated a 25-year-old woman with an esophageal smooth muscle tumor with congenital malformations. Although the large size of the tumor and the presence of hemonecrotic lesion suggested the tumor to be leiomyosarcoma, histological studies revealed it to be leiomyoma. According to previous reports in the English-language literature, the coincidence of esophageal smooth muscle tumor with congenital malformations is relatively rare, and the coincidence of such a tumor with malformations of the type seen in this patient has never been reported. The congenital malformations in our patient were ocular hypertelorism, platyrrhiny, bilateral divergent strabismus, clubbed fingers and toes, fingerprint abnormality, and mild mental retardation. These congenital malformations cannot be explained by any reported syndromes.

Abnormalities, Multiple↗
PubMed2001

Ruptured dissecting aneurysm in bilateral iliac arteries caused by Ehlers-Danlos syndrome type IV: report of a case.

Ehlers-Danlos syndrome (EDS) is an inherited disorder of connective tissue characterized by hyperextensible skin, hypermobile joints, and abnormalities of the cardiovascular system. Ten types and several subtypes of EDS have so far been recognized based on genetic, clinical, and biochemical characteristics. The spectrum of the disorder varies from mild to life-threatening vascular complications. EDS type IV is a particularly dangerous form with a lethal spontaneous rupture of the major arteries and aneurysmal formation. We present herein a case of a ruptured dissecting aneurysm in the bilateral iliac arteries caused by EDS type IV. A previously healthy 33-year-old man without any physical features of this connective tissue disorder experienced a metachronous vascular rupture two times. Successful synthetic bypass grafting was performed with great difficulty. The diagnosis of EDS type IV was made afterwards based on an electrophoresis analysis of a skin biopsy specimen which revealed a lack of type III collagen. Surgical intervention in cases of arterial complications in EDS type IV patients have been reported to be both difficult and frequently unsuccessful. The early clinical recognition of this syndrome is therefore of great importance due to the hazards of such surgical therapies.

Adult↗
PubMed2001

The US2 gene product of herpes simplex virus type 2 interacts with cytokeratin 18.

In order to clarify the biological role of US2 gene product of herpes simplex virus type 2 (HSV-2), a HeLa cDNA library was screened in the yeast two-hybrid system using US2 protein as bait, and several interacting proteins were identified, including cytokeratin 18. US2 protein was co-immunoprecipitated with cytokeratin 18 from HSV-2 infected cell lysates. Analysis of infected orA431 cells by immunofluorescence showed that US2 protein gave filamentous or dot-like cytoplasmic staining pattern, and that it co-localized with cytokeratin 18. When US2 protein was expressed alone, it co-localized with cytokeratin 18. To define the domain interacting with cytokeratin 18, deletion mutant proteins were constructed and cells transfected with mutants were analyzed by indirect immunofluorescence. These results suggest that the N-terminal half of the US2 protein, especially the region containing amino acids 42-77, is important for interaction with cytokeratin 18.

Animals↗
PubMed2001

Hip-shelf procedure in the treatment of osteonecrosis of the transpositioned acetabulum after rotational acetabular osteotomy.

Necrosis of the transpositioned acetabulum after rotational acetabular osteotomy (RAO) is a major complication characteristic of this procedure. This complication, although rare, has been thought difficult to treat. We report a patient with acetabular osteonecrosis and subsequent collapse after RAO that was effectively treated with a shelf operation, providing satisfactory remodeling of the hip joint. A 16-year-old female had undergone RAO for the treatment of developmental acetabular dysplasia. Postoperative radiography showed that the osteotomized acetabular fragment was unusually thin, and that the osteotome entered the hip joint during the surgery. Five months after the RAO, X-rays revealed significant collapse of the transpositioned acetabulum, and femoral head subluxation caused by postoperative osteonecrosis. Seven months after the RAO, the patient underwent a hip-shelf procedure. The remaining acetabular fragment was used in this procedure, according to the Spitzy method. Seven years after the second operation, favorable remodeling of the hip joint was observed; however, early osteoarthritic changes, including slight joint space narrowing, bone sclerosis of the new acetabulum, and bone cysts within the femoral head, were seen.

Acetabulum↗
PubMed2001

Fibroblast growth factor-2 decreases hyperoxia-induced photoreceptor cell death in mice.

Fibroblast growth factor-2 (FGF2) has neurotrophic effects in vitro and in vivo. It has been demonstrated to decrease photoreceptor cell death in rats exposed to constant light and in rats with an inherited defect in retinal pigmented epithelium (RPE) phagocytosis, but the effects of intravitreous injections of FGF2 in mice are equivocal. In this study, we used transgenic mice with increased expression of FGF2 in photoreceptors (rhodopsin promoter/FGF2 transgenics) to investigate the effects of sustained increased expression of FGF2 in mice with various types of photoreceptor degeneration, including rd mice that are homozygous for mutated phosphodiesterase beta subunit, Q344ter mice that undergo photoreceptor degeneration because of expression of mutated rhodopsin, and mice exposed to 75% oxygen for 1 or 2 weeks. At P21, the outer nuclear layer was markedly reduced in rd mice or Q344ter mice regardless of whether they inherited the rhodopsin promoter/FGF2 transgene. However, after 2 weeks of exposure to 75% oxygen, outer nuclear layer thickness was significantly reduced in littermate control mice compared to FGF2 transgenic mice (P = 0.0001). These data indicate that increased expression of FGF2 in photoreceptors protects them from hyperoxia-induced damage, but does not decrease cell death related to expression of mutated proteins involved in the phototransduction pathway. This suggests that FGF2 protects photoreceptors from oxidative damage, which may play a role in complex genetic diseases such as age-related macular degeneration.

Aging↗
PubMed2001

Development of a yeast stop codon assay readily and generally applicable to human genes.

We established a yeast-based method to screen chain-terminating mutations that is readily applicable to any gene of interest. Based on the finding that 18- to 24-base-long homologous sequences are sufficient for gap repair in vivo in yeast, we used a strategy to amplify a test-gene fragment with addition of 24-bp sequences homologous to both cut-ends of a yeast expression vector, pMT18. After co-transformation with the amplified fragment and the linearized pMT18, each yeast (Saccharomyces cerevisiae) cell automatically forms a single-copy circular plasmid (because of CEN/ARS), which expresses a test-gene::ADE2 chimera protein. When the reading frame of the test-gene contains a nonsense or frameshift mutation, truncation of the chimera protein results in lack of ADE2 activity, leading to formation of a red colony. By using a nested polymerase chain reaction using proofreading Pfu polymerase to ensure specificity of the product, the assay achieved a low background (false positivity). We applied the assay to BRCA1, APC, hMSH6, and E-cadherin genes, and successfully detected mutations in mRNA and genomic DNA. Because this method--universal stop codon assay--requires only 4 to 5 days to screen a number of samples for any target gene, it may serve as a high-throughput screening system of general utility for chain-terminating mutations that are most prevalent in human genetic diseases.

Adenomatous Polyposis Coli Protein↗
PubMed2001

Disruption of nuclear factor-interleukin-6, a transcription factor, results in severe mycobacterial infection.

Nuclear factor-interleukin-6 (NF-IL-6) is one of several nuclear transcription factors (NF-IL-6, NF-kappaB, PU.1, interferon-regulatory factor 1, Egr-1, and Stat-1). NF-IL-6 and NF-kappaB are expressed in macrophages and is induced by bacterial lipopolysaccharides. To evaluate whether NF-IL-6 is required for the inflammatory immune response to mycobacterial infection, in which epithelioid macrophages comprise the leading cell population, we generated NF-IL-6 knockout (KO) mutant mice. Airborne infection of these mice with Mycobacterium tuberculosis strains induced disseminated tuberculosis lacking granuloma formation, although interferon-gamma, tumor necrosis factor-alpha, and interleukin-12 mRNA expression levels were within the normal range compared with those of wild-type mice. Generation of O2- and mycobacterial killing by neutrophils from these mice were impaired severely compared with wild-type mice. We conclude that NF-IL-6 is a critical transcription factor in mycobacterial control as well as in granulocyte-colony stimulating factor induction resulting in neutrophil activation.

Animals↗
PubMed2001

Alpha-fetoprotein microheterogeneity: a potential biochemical marker for Down's syndrome.

Our purpose was to examine the utility of analyzing alpha-fetoprotein (AFP) microheterogeneity assessed by lectin affinity in Down's syndrome (DS) screening. Maternal sera and amniotic fluids were collected from 18 women who were carrying DS fetuses and 70 unaffected pregnancies around 16 weeks of gestation. The percentages of AFP which reacted with Lens culinaris agglutinin (AFP-L2,3) were determined by lectin affinity electrophoresis. AFP-L2,3 levels were significantly increased (P<0.0001) in both maternal serum and amniotic fluid from DS-affected versus unaffected pregnancies. The fractional areas under the receiver operating characteristic curves were 0.835 and 0.700 (P=0.106) for AFP-L3 and AFP MoM (multiples of the median) in maternal serum. No correlation was found between AFP-L3 and AFP MoM in maternal serum (r=0.006). Our data suggest that the measurement of AFP-L3 in maternal serum is a potential biochemical marker for DS.

Amniotic Fluid↗
PubMed2001

Heparin-stimulated expression of extracellular-superoxide dismutase in human fibroblasts.

Extracellular-superoxide dismutase (EC-SOD) is the major SOD isozyme in the arterial wall and may be important for antioxidation capability of the vascular wall and normal vascular function. EC-SOD is expressed in various cell types in the vascular wall such as fibroblasts, smooth muscle cells and macrophages, and the synthesis of EC-SOD by human fibroblasts is known to be highly responsive to various inflammatory cytokines, although there is no response to oxidative stress. Heparin is a highly sulfated glycosaminoglycan with many functions such as antithrombotic, antilipemic and antiatherosclerotic effects. Another less well-known function of heparin is regulation of protein synthesis. In this study, we measured the induction of EC-SOD after treatment with heparin to understand the role of heparin in the antiatherosclerotic response of fibroblasts. Heparin induced EC-SOD expression at both the mRNA and protein levels. Heparin showed the greatest stimulatory effect and heparan sulfate showed moderate effects. The effect of chondroitin sulfate A was not clear. In contrast, desulfated heparin and chondroitin sulfate C did not increase EC-SOD expression. The stimulatory effect seemed to increase roughly with the degree of glycosaminoglycan sulfation. The enhanced expression of EC-SOD by heparin must contribute to the antiatherosclerotic effect of heparin.

Base Sequence↗
PubMed2001

Evaluation of the treatment performance of a multistage ozone/hydrogen peroxide process by decomposition by-products.

The performance of a multistage ozone/hydrogen peroxide (O3/H2O2) process was evaluated with respect to total organic carbon (TOC) removal of waste waters. An aqueous humic acid solution (5.2 mgC l(-1) as TOC) and a sand filtered secondary sewerage effluent (5.6mgC l(-1) as TOC) were used as model waste waters. Appropriate range of hydrogen peroxide (H2O2) dose at each stage depended upon the components of the tested solutions that changed as the process proceeded. Higher hydrogen peroxide dose was required at later stages in which low reactivity compounds with hydroxyl radical (HO*), low molecular fatty acids, were predominant. And, oxalic acid concentration related to H2O2 demand at later stages. This was assumed that the slow decomposition of oxalic acid was rate-determining step for TOC removal after its accumulation. Also, it is important to maintain dissolved ozone at low concentration for efficient TOC removal because rapid ozone consumption is required for the rapid formation of hydroxyl radical (HO*).

Carbon↗
PubMed2001

Massive intravenous immunoglobulin treatment in pregnancy complicated by Guillain-Barré Syndrome.

A pregnant woman developed acute demyelinating poly-neuropathy (Guillain-Barré syndrome (GBS)) in the 28th week of gestation (GW) after flu-like infection. Hypertension, liver dysfunction, and a decrease in consciousness level developed at 29GW. Blood chemical analysis revealed increased levels of liver enzymes GOT 247 IU/l and GPT 624 IU/l. Viral serological study showed a positive test for Epstein-Barr virus IgM. Weakness of bilateral facial muscles and limbs, a loss of tendon reflexes, and generalized paresthesia were detected by neurologic examinations. Over the course of 5 days, a massive dose (100g) of intravenous immunoglobulin (MIVIg) was infused in 30GW. An average manual muscle testing score by the Medical Research Council method and peak flow value began to be significantly restored during and after MIVIg infusions. Values of the liver enzymes gradually decreased, and improvement of the muscle weakness and dysbasia was observed. Her pregnancy normally ended in spontaneous vaginal delivery of a healthy infant in 37GW. This is the first report confirming the efficacy of MIVIg, without plasmapheresis, in GBS-complicated pregnancy.

Adult↗
PubMed2001

Long-term prognosis of patients with West syndrome in Japan: social aspects.

Long-term social prognosis of 120 Japanese patients with West syndrome was surveyed using structured questionnaire at the age of 25.4 years in average. The survey revealed that ADL score remained null in one-fifth of cases; the majority entered in special education course for disabled children; only eleven cases were employed as a full-time worker. As to QOL, 60% of cases were spending daily life with joy. In summary, social prognosis of West syndrome is generally gloomy, but a proportion of patients can lead an independent social life, and an enriched social environment is the most influential factor for better prognosis

Adult↗
PubMed2001

Long-term prognosis of patients with West syndrome in Japan: medical aspects.

In this study, West syndrome prognosis over 20 years was described. All information was obtained from the primary caregivers of patients with West syndrome thorough questionnaires. Of the 259 respondents, 117 patients born between 1960 and 1980 were analyzed. At the age of 20 years two patients were deceased, of the surviving patients, 40% of patients had seizures daily or weekly and 25.2% had been seizure-free for at least 3 years. There was significant difference in the seizure persistence value between West syndrome etiologies but not between the birth cohorts; of those born in the 1960s and 1970s. Compared with severe seizure persistence, which was the duration of the existing daily or weekly seizures at each age, there were no significant difference between birth cohorts and West syndrome etiologies.

Adolescent↗
PubMed2001

An fMRI study of the functional neuroanatomy of picture encoding in younger and older adults.

Age-related changes in the neural mechanisms of picture encoding were investigated using functional magnetic resonance imaging (fMRI). Seven younger and seven older adults were studied while they were encoding pairs of concrete-related, concrete-unrelated, and abstract pictures. Functional (T2*-weighted) and anatomical (T1-weighted) images of the brain were obtained using a 1.5 T MRI scanner. The results in the younger adults showed that the left dorsal prefrontal cortex (PFC) was activated during associative learning of the concrete-unrelated or abstract pictures. The results also suggest that both ventral and dorsal visual pathways are involved in the encoding of abstract pictures, and that the right superior parietal lobule likely mediates spatial information of the abstract pictures. The older adults showed significant activation in the left dorsal PFC under concrete-unrelated and abstract conditions. However, the older adults failed to activate either the left ventral and right dorsal PFC under the concrete-unrelated condition, or the parietal areas under abstract condition. A direct comparison between the two age groups demonstrates that the older adults had a reduced activation in the bilateral parieto-temporo-occipital areas under abstract condition, and in the right temporo-occipital area extending to the fusiform gyrus under the concrete-unrelated condition. Finally, age difference was found in correlation between memory performance and amplitude of signal change in the parahippocampal gyrus and fusiform gyrus under the concrete-unrelated and abstract conditions. These changes in neural response likely underlie the age-related memory decline in relation to pictorial information.

Adult↗
PubMed2001

Influence of contraction force and speed on muscle fiber conduction velocity during dynamic voluntary exercise.

Before using electromyographic (EMG) variables such as muscle fiber conduction velocity (MFCV) and the mean or median frequency (MDF) of an EMG power spectrum as indicators of muscular fatigue during dynamic exercises, it is necessary to determine the influence of a joint angle, contraction force and contraction speed on the EMG variables. If these factors affect the EMG variables, their influence must be removed or compensated for before discussing fatigue. The vastus lateralis of eight normal healthy male adults was studied. EMG signals during non-fatiguing dynamic knee extension exercises were detected with a three-bar active surface electrode array. EMG variables were calculated from the detected signals and compared with the angle of the knee joint, the extension torque and the extension speed. The extension torque was set at four levels with 10% intervals between 40 and 70% of the maximum voluntary contraction. The extension speed was set at five levels with 60 degrees /s intervals between 0 and 240 degrees /s. Because the joint angle unsystematically affected the MFCV, EMG variables at a given joint angle were extracted for comparison. The influence of the extension torque and speed on the extracted EMG variables was clarified with an ANOVA and a regression analysis. The statistical analyses showed that MFCV increased with the extension torque but did not depend on the extension speed. In contrast, MDF was independent of the extension torque but was dependent on the extension speed. MDF thus showed a behavior different from that of MFCV. It became clear that if MFCV is used as an indicator of muscular fatigue during dynamic exercises, it is at least necessary to extract MFCV at a predetermined joint angle and then remove the influence of extension torque on MFCV.

Action Potentials↗
PubMed2001

Pressure-dependent changes in the structure of the melittin alpha-helix determined by NMR.

A novel method is described, which uses changes in NMR chemical shifts to characterise the structural change in a protein with pressure. Melittin in methanol is a small alpha-helical protein, and its chemical shifts change linearly and reversibly with pressure between 1 and 2000 bar. An improved relationship between structure and HN shift has been calculated, and used to drive a molecular dynamics-based calculation of the change in structure. With pressure, the helix is compressed, with the H-O distance of the NH-O=C hydrogen bonds decreased by 0.021 +/- 0.039 A, leading to an overall compression along the entire helix of about 0.4 A, corresponding to a static compressibility of 6 x 10(-6) bar(-1). The backbone dihedral angles phi and psi are altered by no more than +/- 3 degrees for most residues with a negative correlation coefficient of -0.85 between phi(i) and psi(i - 1), indicating that the local conformation alters to maintain hydrogen bonds in good geometries. The method is shown to be capable of calculating structural change with high precision, and the results agree with structural changes determined using other methodologies.

Amides↗