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Biomedical subjects

T Yasuda

Publications and source records attributed to T Yasuda.

At least 235 records · Page 13Linked to original sources
PubMed1998

Ultrastructural assessment of the myocardium receiving intermittent antegrade warm blood cardioplegia.

Ultrastructural changes in the myocardium during intermittent warm blood cardioplegia were studied in 12 dogs. During cardiopulmonary bypass, dogs received three 5-minute periods of warm blood cardioplegia, interrupted by three 10-minute episodes of ischemia in group A or three 20-minute episodes of ischemia in group B. Biopsy specimens were taken from the right ventricle before each cardioplegic infusion and at the end of the aortic cross-clamp period to analyze ultrastructural changes. Functional recovery was measured after cardiopulmonary bypass. Mild and principally reversible ultrastructural changes were observed in group A. In group B, moderate ultrastructural changes were observed, and these changes suggested cumulative ischemic injury. Functional recovery was good in group A, but significantly deteriorated in group B. We concluded that three 10-minute interruptions of warm blood cardioplegia cause mild ultrastructural changes and seem to be safe, but three 20-minute interruptions cause cumulative ischemic injury in normal dog hearts.

Animals↗
PubMed1998

Structural changes in the oligosaccharide moiety of human IgG with aging.

In order to elucidate the relationship between glycosylation of IgG and aging, oligosaccharide structures of human IgG purified from sera of men and women aged 18 to 73 years were investigated. Oligosaccharides were liberated quantitatively from IgG by hydrazinolysis followed by N-acetylation and were tagged with p-aminobenzoic acid ethyl ester. The oligosaccharide structures were then analyzed by HPLC in conjunction with sequential exoglycosidase digestion. All IgG samples were shown to contain a series of biantennary complex type oligosaccharides which consisted of +/-Galbeta1-4GlcNAcbeta1-2Manalpha1-6(+/-GlcNAcbeta 1-4)(+/-Galbeta1-4GlcNAcbeta1-2Man(alpha)1-3)Man(beta)1-+ ++4GlcNAcbeta1-4(+/- Fucalpha1-6)GlcNAc and their mono- and disialo glycoforms in different ratios. In female IgG samples only, the incidence of non-galactosylated oligosaccharides with non-reducing terminal GlcNAc residues increased with aging (r>0.8), whereas that of digalactosylated oligosaccharides decreased (r<-0.8). A weaker correlation was observed between aging and the incidence of neutral and monosialo oligosaccharides in female IgG (r=0.461 and r= -0.538, respectively) and between aging and the incidence of oligosaccharides with a bisecting GlcNAc in both male and female IgG samples (r=0.566 and r=0.440, respectively). In addition, a significant change with aging in the galactosylation of IgG oligosaccharides was observed in females in their thirties, fifties, and sixties (p<0.02, p<0.01, and p<0.04, respectively). These findings may contribute to our understanding of autoimmune diseases such as rheumatoid arthritis in which glycosylation is involved.

Adolescent↗
PubMed1998

Expression of mRNAs for neurotrophins (NGF, BDNF, and NT-3) and their receptors (p75NGFR, trk, trkB, and trkC) in human peripheral neuropathies.

The steady-state mRNA levels of NGF, BDNF and NT-3, and the mRNA levels of their receptors p75NGFR, trk, trkB, and trkC were examined in various human peripheral neuropathies, to determine the correlation with myelinated fiber pathology and T cell and macrophage invasions in the diseased nerves. Steady state levels of p75NGFR mRNAs were significantly elevated in nerves with axonal pathology. In contrast, steady state levels of trkB and trkC mRNA levels were diminished. trk mRNA was not detected in the human nerves. The NGF, BDNF, and NT-3 mRNA levels were elevated in the diseased nerves. The increase in BDNF and NT-3 mRNA levels were proportional to the extent of invasion of the nerves by T cells and macrophages, but did not directly correlate with axonal nor demyelinating pathology, thus suggesting that inflammatory cell invasions are involved in the regulation of BDNF and NT-3 mRNA expressions. These neurotrophin and their receptor gene expressions in the diseased human nerves would be regulated by an underlying pathology-related process, and could play a role in peripheral nerve repair.

Brain-Derived Neurotrophic Factor↗
PubMed1998

Structure and organization of the human deoxyribonuclease II (DNase II) gene.

The structure of the human gene for deoxyribonuclease II (DNase II; EC 3.1.22.1) was determined using several specific primers based on the human DNase II cDNA sequence [Yasuda et al. (1998). J. Biol. Chem. 273, 2610-2616] in a polymerase chain reaction-based strategy. The gene spanned about 6 kb and consisted of 6 exons. No canonical TATA or CAAT boxes could be identified within the 1341 nucleotides upstream of the putative transcription start site, although the 5'-flanking region contained a CpG island and several putative binding motifs for transcription factors Sp1 and ETF. These properties indicate that the DNase II gene is a housekeeping gene and this is compatible with its ubiquitous expression in human tissues. Three different cleavage/polyadenylation sites were identified in the 3'-flanking region, leading to the production of multiple DNase II mRNA species. However, a comparison of the entire translated sequences of the gene from a pair of subjects with homozygous DNase II phenotypes H and L revealed no differences in the nucleotide sequences.

Base Sequence↗
PubMed1998

Antitumor effect of diphtheria toxin A-chain gene-containing cationic liposomes conjugated with monoclonal antibody directed to tumor-associated antigen of bovine leukemia cells.

Monoclonal antibody c143 against tumor-associated antigen (TAA) expressed on bovine leukemia cells was conjugated to cationic liposomes carrying a plasmid pLTR-DT which contained a gene for diphtheria toxin A-chain (DT-A) under the control of the long terminal repeat (LTR) of bovine leukemia virus (BLV) in the multicloning site of pUC-18. The specificity and antitumor effects of the conjugates were examined in vitro and in vivo using TAA-positive bovine B-cell lymphoma line as the target tumor. In vitro studies with the TAA-positive cell line indicated that luciferase gene-containing cationic liposomes associated with the c143 anti-TAA monoclonal antibody caused about 2-fold increase in luciferase activity compared with cationic liposomes having no antibody, and also that the c143-conjugated cationic liposomes containing pLTR-DT exerted selective growth-inhibitory effects on the TAA-positive B-cell line. Three injections of pLTR-DT-containing cationic liposomes coupled with c143 into tumor-bearing nude mice resulted in significant inhibition of the tumor growth. The antitumor potency of the c143-conjugated cationic liposomes containing pLTR-DT was far greater than that of normal mouse IgG-coupled cationic liposomes containing pLTR-DT as assessed in terms of tumor size. These results suggest that cationic liposomes bearing c143 are an efficient transfection reagent for BLV-infected B-cells lymphoma cells, and that the delivery of the pLTR-DT gene into BLV-infected B-cells by the use of such liposomes may become a useful technique for gene therapy of bovine leukosis.

Animals↗
PubMed1998

Two-dimensional dose distribution of a miniature x-ray device for stereotactic radiosurgery.

The Photon Radiosurgery System is a miniature x-ray device developed for the treatment of small intracranial neoplasms. The x-rays are generated at the tip of a 10-cm-long, 3-mm-diam probe with a nearly isotropic distribution. Results from measurements of the two-dimensional dose distribution around the x-ray source are presented using two methods: (1) dose measurement with an ionization chamber and a water phantom system and (2) dose measurement with radiochromic film and a solid water phantom. The shape of the two angular dose distributions in the axial plane agree with each other to with approximately 10% and the dose at 10 mm from the source, orthogonal to the probe axis, was about 20% lower than at the same distance along the axis. The relative dose difference of 20% corresponds to a change in distance from the source of +/- 0.3 mm at 10 mm. It is shown that the anisotropy of radiation distribution in the axial plane can be improved to approximately 10% by adjusting the electron beam with a 12% reduction in the overall radiation output.

Calibration↗
PubMed1998

20-Hz flicker stimulus can isolate the cone function in rat retina.

Cone electroretinograms (ERGs) are typically isolated in humans by flicker stimuli against rod-desensitizing adapting fields. To investigate the manner in which adapting-field luminance affects the cone ERGs, we recorded ERGs in normal albino Sprague-Dawley rats with flicker stimuli presented against adapting fields that ranged in luminance from to 1.75 log cd/m2. A flicker rate of 20 Hz was used to isolate the cone ERGs under all adaptation conditions. We found the amplitudes of cone ERGs to increase with increasing adapting-field luminance. These response characteristics are similar to human ERGs using 30-Hz flicker stimuli, which suggests that flicker stimuli are a useful technique to isolate the cone function in rats.

Adaptation, Ocular↗
PubMed1998

Detection of deoxyribonuclease I along the secretory pathway in Paneth cells of human small intestine.

The expression and distribution of deoxyribonuclease I (DNase I) in human duodenum, jejunum and ileum were examined by DNase I activity assay and the reverse transcriptase-polymerase chain reaction (RT-PCR), immunofluorescence, in situ hybridization, and immunocytochemical ultrastructural analyses. High levels of DNase I were detected in the cytoplasm of Paneth cells in human small intestine. A tissue homogenate fraction rich in Paneth cells showed strong DNase I-specific enzymatic activity. Immunofluorescence analysis using several specific anti-human DNase I antibodies showed very strong immunoreactivity in the cytoplasm of every Paneth cell. In situ hybridization demonstrated high levels of DNase I mRNA in Paneth cells. Immunogold electron microscopy revealed gold particles localized along the secretory pathway, with the exocrine secretory granules mostly labeled. Our findings strongly suggest that Paneth cells synthesize and secrete DNase I into the intestinal lumen.

Adult↗
PubMed1998

Antiphospholipid antibodies and atherosclerosis.

Beta2-Glycoprotein I (beta2-GPI) is a major antigen for anticardiolipin antibodies (aCL) induced in patients with antiphospholipid syndrome and their antigenic epitopes are cryptic. The epitopes appear on the surface of beta2-GPI molecule only when beta2-GPI interacts with lipid membranes containing negatively charged phospholipids or polyoxygenated polystyrene surface. Our data also indicated that CuSO4-oxidized low density lipoproteins (oxLDL) are subsequently targeted by beta2-GPI and aCL; however, malonedialdehyde (MDA)-modified LDL were recognized neither by beta2-GPI nor aCL. Beta2-GPI binding to LDL was rapidly increased by incubation with CuSO4. Oxidation of lipoproteins was accompanied with the increment of thiobarbituric acid-reactive substances (TBARS) and denature of apolipoprotein. Ligands on LDL for beta2-GPI seemed to be intermediate oxidative derivatives which were extractable into the chloroform phase by Bligh and Dyer's extraction, but not MDA. Further, immune responses against beta2-GPI, as an anti-atherogenic protein, were demonstrated to induce atherogenic effect in in vitro oxLDL uptake by macrophages.

Antibodies, Anticardiolipin↗
PubMed1998

Osteochondral lesions of the proximal phalanx of the great toe: a report of two cases.

Two cases of osteochondral lesions of the proximal phalanx of the great toe at the interphalangeal joint are presented. This condition is characterized by pain, swelling, and tenderness at the interphalangeal joint. The roentgenographic characteristics resemble osteochondritis dissecans. Curettage and bone grafting to the lesion is effective. These conditions in adolescent soccer players may be caused by chronic repetitive overloading of the interphalangeal joint using soccer shoes with soft, supple, and narrow toe boxes.

Adolescent↗
PubMed1998

Ventilatory control during exercise in normal children.

We investigated the relation between age and respiratory control during exercise in 80 children aged 6.4-17.6 y (42 male, age, 11.6 +/- 3.3 y; body weight, 41.3 +/- 14.7 kg; and 38 female, age, 12.6 +/- 2.7 y; body weight, 42.5 +/- 9.3 kg). Exercise tests were performed on a treadmill after a standard symptom-limited Bruce protocol. Data were analyzed separately for boys and girls. At rest and at peak exercise, the ratio of minute ventilation to carbon dioxide production (VE/VCO2), the ratio of effective alveolar ventilation to carbon dioxide production (VA/VCO2), the ratio of pulmonary dead space to tidal volume (Vd/Vt), and arterial PCO2 (PaCO2) were not correlated with age. At the exercise intensity of ventilatory anaerobic threshold, the PaCO2 increased, and the VA/VCO2 decreased, significantly with age, whereas the Vd/Vt was not related to age. Linear regression analysis demonstrated that the slope of the relationship between VE and VCO2 (deltaVE/deltaVCO2) and the slope of the relationship between VA and VCO2 (deltaVA/deltaVCO2) decreased with age. There were no gender differences in the regression slopes and the intercepts of the relationships. Results show that younger children breathe more during exercise to eliminate a given amount of CO2 to keep PaCO2 set point slightly but significantly lower than older children. This age dependence must be considered in investigating ventilatory control during exercise in children.

Adolescent↗
PubMed1998

Difference in height associated with a translation start site polymorphism in the vitamin D receptor gene.

The function of 1,25-dihydroxyvitamin D3 in bone development is to regulate the differentiation or proliferation of osteoblastic, osteoclastic, and chondrocytic lineage, affecting bone mineralization and linear bone growth. An A(T/C)G substitution exists in the first of the two putative translation initiation sites in exon 2 of the vitamin D receptor (VDR) gene. We studied the relationship between exon 2 polymorphism and height in 90 healthy Japanese female subjects aged 18-20 y, who had attained final height, in 159 healthy Japanese aged 13 y, and 24 children with constitutional short stature aged 6-10 y less than -1.5 SD in height, mostly with parents of normal height. Exon 2 polymorphism was analyzed by PCR-single strand conformation polymorphism, PCR-direct sequencing, and PCR-restriction fragment length polymorphism. The frequency of the exon 2 polymorphism was genotype CC (ACG/ACG), 0.37; genotype CT (ACG/ATG), 0.51; and genotype TT (ATG/ATG), 0.12 in 249 normal subjects. The mean height of female subjects aged 18-20 y with the genotype CT was 160.3 +/- 4.3 cm (mean +/- SD), whereas that with CC was 4.4 cm lower (p < 0.0001), and that with TT was 2.7 cm lower (p = 0.0302). At age 13 y, this trend was observed, and the mean height SD score of subjects with the genotype CT was taller than homozygotes (CC/CT; p = 0.0363 and CT/TT; p = 0.0208) in 159 subjects. Genotype CT in 24 children with constitutional short stature was less frequent than other genotypes (CC, 0.62; CT, 0.21; TT. 0.17) (chi 2 p value, 0.0171). In conclusion, the exon 2 polymorphism affecting the VDR mRNA and protein is one of the major determinants of adult height at least in female Japanese, which was noted at the age of 13 y examined in both sexes.

Adolescent↗
PubMed1998

Familial hypoparathyroidism: identification of a novel gain of function mutation in transmembrane domain 5 of the calcium-sensing receptor.

Activating mutations of the extracellular calcium (Ca2+e)-sensing receptor (CaR) gene, mostly in its extracellular domain, can cause both familial and sporadic hypoparathyroidism. We report a Japanese family with severe hypoparathyroidism with pretreatment serum calcium (Ca) levels of 4.9-5.9 mg/dL. The proband presented with a seizure at 6 days of age. Her older brother and mother, who had also experienced seizures and tetany, respectively, likewise had hypoparathyroidism. A heterozygous missense mutation substituting a cysteine for the phenylalanine normally present at codon 788 (F788C) was identified in the CaR's fifth transmembrane domain and was shown to cosegregate with the disease. The mutation was absent in DNA from 50 control subjects. Analysis of the functional properties of the mutant receptor was carried out in transiently transfected HEK293 cells loaded with fura-2 by assessing Ca2+e-evoked increases in the cytosolic calcium concentration (Ca2+i). There was a leftward shift in the concentration-response curve for the mutant receptor [EC50 (effective concentration of Ca2+e producing half of the maximal Ca2+i response, 2.7 +/- 0.1 vs. 4.1 +/- 0.1 mmol/L for the wild-type receptor]. HEK293 cells cotransfected with both the wild-type and mutant CaRs (to mimic the heterozygous state in affected family members) showed an EC50 (3.0 +/- 0.1 mmol/L) similar to that of the mutant CaR alone. Thus, we confirm that 1) a gain of function mutation in the fifth transmembrane domain of the CaR causes severe familial hypoparathyroidism by rendering the receptor more sensitive than normal to activation by Ca2+e; 2) some patients in the family do not experience seizures despite their severe hypocalcemia; and 3) this condition needs to be differentiated from other causes of hypoparathyroidism.

Blotting, Western↗
PubMed1998

Urinary metabolites of daidzin orally administered in rats.

In a study on the metabolism of flavonoids, the isoflavone glycoside daidzin was orally administered to rats. Urine samples were collected and treated with beta-glucuronidase and arylsulfatase. Aglycone daidzein (M3) and other three metabolites, 3',4',7-trihydroxyisoflavone (M1), 4',7-dihydroxyisoflavanone (M2) and 4',7-dihydroxyisoflavan (M4) were isolated from the urine following treatment with enzymes. The structures of M1, M2 and M4 were determined on the basis of chemical and spectral data.

Administration, Oral↗
PubMed1998

Use of temporary vena cava filters after catheter-directed fragmentation and thrombolysis in patients with acute pulmonary thromboembolism.

Acute pulmonary thromboembolism is a life-threatening disease and in almost all cases originates from deep venous thrombosis in the proximal deep venous system of the legs. In order to prevent further episodes of thromboembolism in 2 patients with acute pulmonary thromboembolism, we inserted an Antheor temporary vena cava filter after catheter-directed fragmentation and thrombolysis. No complications occurred during the insertion of the filters and our results suggest that this filter device may be clinically safe and effective for temporary protection against pulmonary thromboembolism.

Aged↗
PubMed1998

Autosomal dominant familial hypoparathyroidism and sensorineural deafness without renal dysplasia.

OBJECTIVE: A family is described which has a unique combination of autosomal dominant hypoparathyroidism and sensorineural deafness without renal dysplasia. CASE REPORT: The proband was a male infant aged 1 month with episodes of seizures for 20 days. He was born at 35 weeks' gestation without asphyxia, weighing 2040 g. His initial calcium, phosphorus and percentage of tubular reabsorption of phosphorus were 6.8 mg/dl (normal range 8.5-10.5 mg/dl), 8.9 mg/dl (normal range 5.5-7.4 mg/dl) and 96.8% (normal range 85-95%) respectively. He had normal values for serum parathyroid hormone (PTH) and 25-hydroxyvitamin D. No abnormalities were found by renal imaging and a routine renal function study. He showed a brisk plasma cAMP increase in response to human PTH-(1-34) infusion. He had normal karyotype 46, XY, without a microdeletion in chromosome 22q11.2 by an in situ hybridization method. Five family members were affected with hypoparathyroidism with sensorineural deafness with autosomal dominant transmission. The study of calcium-sensing receptor and preproPTH gene showed a normal DNA sequence. CONCLUSION: The combination of familial hypoparathyroidism with sensorineural deafness without renal dysplasia is novel and the cause may be distinct from previously reported familial hypoparathyroidism with sensorineural deafness and renal dysplasia.

Adult↗