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Y Kuroda

Publications and source records attributed to Y Kuroda.

At least 577 records · Page 32Linked to original sources
PubMed1993

Theoretical analysis of amino acid sequence of human dystrophin.

Human muscular dystrophy, the fatal disease, is caused by the genetic abnormality of dystrophin. The question whether dystrophin is an intrinsic membrane protein or not was investigated by calculating the average value and the long periodicity of hydrophobicity of amino acid sequence. The periodicity was estimated by a maximum entropy method of Fourier transformation. The results indicated that a fragment from 3101-st to 3200-th residues of dystrophin contains several transmembrane helices. The hydropathy plot of this region strongly suggests four transmembrane helices, indicating that both ends, N-and C-termini, are located in the cytoplasmic sides with firm anchoring into membrane by these helices.

Amino Acid Sequence↗
PubMed1993

[Clinical utility of Gd-DTPA subtraction MR imaging for spinal bone metastasis].

Based on reports that Gd-DTPA contributes to the detection of tumors, we used it in 31 cases (97 lesions) of spinal bone metastases. The result was that Gd-DTPA increased the intensity of tumors and the surrounding bone marrow to almost the same level in 53%. To show the metastases clearly, an existing subtraction command system was utilized. The technique included the pixel-by-pixel method, to obtain a Gd-DTPA T1-weighted image (T1WI) subtracted by the original T1WI. The detectability of the subtraction image was improved up to 96%, but was less than the original T1WI (99%). Because of the different imaging rationale between two methods, a means to assess the quality of diagnosis must be proposed. To check the normal background, the same kind of postprocessing was performed in 21 patients without malignancy. Gd-DTPA perfusion was highest in the paravertebral veins, moderate in muscles and epidural fat, and lowest in the spinal cord, intervertebral disk and bone cortex. Gd-DTPA enhanced subtraction MR imaging provides a new diagnostic tool to detect and to assess bone metastasis.

Adult↗
PubMed1993

Residual helical structure in the C-terminal fragment of cytochrome c.

Several reports have pointed out the existence of both kinetic and equilibrium intermediate states in protein folding. In cytochrome c, it has been shown that the N- and C-terminal helices form in the early stages of folding and remain stable in the molten globule state (a compact equilibrium intermediate). These two facts prompted me to synthesize and examine the helical content, in aqueous solution, of the peptides corresponding to the three major helices of cytochrome c. These peptides are 15 residues long. This paper reports that little if any helix is present in the N-terminal and 61-75 peptides, regardless of the pH and salt concentration. However, the C-terminal peptide showed a far-UV CD spectrum characteristic of an alpha-helix (27% helicity). The helical content of the C-terminal peptide increased to 43% as salt (2 M Na2SO4) was added. The dimerization of the C-terminal peptide with the N-terminal peptide by an SS bridge stabilized the helical structures (14% to 63% helicity). These results strongly suggest that the C-terminal helix is essential for both the folding and the stability of cytochrome c. Furthermore, although the N-terminal segment does not form helices by itself, its interaction with the C-terminal helix would enhance the stability of the subdomain containing the two helices.

Amino Acid Sequence↗
PubMed1993

The effect of posttranslational modifications on the interaction of Ras2 with adenylyl cyclase.

Ras proteins undergo a series of posttranslational modifications that are critical for their cellular function. These modifications are necessary to anchor Ras proteins to the membrane. Yeast Ras2 proteins were purified with various degrees of modification and examined for their ability to activate their effector, adenylyl cyclase. The farnesylated intermediate form of Ras2 had more than 100 times higher affinity for adenylyl cyclase than for the unprocessed form. The subsequent palmitoylation reaction had little effect. In contrast, palmitoylation was required for efficient membrane localization of the Ras2 protein. These results indicate the importance of farnesylation in the interaction of Ras2 with its effector.

Adenylyl Cyclases↗
PubMed1993

Abnormal signal-averaged electrocardiogram in patients with Duchenne muscular dystrophy: comparison of time and frequency domain analyses from the signal-averaged electrocardiogram.

The clinical significance of an abnormal signal-averaged electrocardiogram (SA-ECG) in time- and frequency-domain analyses was assessed in patients with Duchenne muscular dystrophy (DMD). Twenty-four DMD patients and 20 age-matched healthy volunteers were studied. The SA-ECG was recorded by time-domain signal processing using the vector-magnitude method and frequency-domain signal processing using the fast-Fourier transform. Abnormal SA-ECGs were based on comparison with controls and eight abnormal SA-ECGs were detected among 24 DMD patients, seven by frequency-domain analysis and four by time-domain analysis. The end-diastolic left ventricular volume was larger in the patients with abnormal SA-ECG than in those with normal SA-ECG (136 +/- 32 ml vs. 77 +/- 43 ml, p < 0.01). Compared with patients with normal SA-ECGs, the DMD patients with abnormal SA-ECGs had a lower left ventricular (LV) ejection fraction (54 +/- 6 vs. 61 +/- 8%, p < 0.05), as an index of LV contractility, and less LV posterior wall velocity (46 +/- 9 mm/min vs. 62 +/- 16 mm/min, p < 0.01), as an index of LV relaxation. The sensitivity and specificity of frequency-domain analysis for predicting malignant ventricular arrhythmias was 60 and 85%, respectively, compared with 30 and 92%, respectively, for time-domain analysis. The combination of time- and frequency-domain analyses can facilitate identification of DMD patients with ventricular tachyarrhythmias associated with depression of cardiac performance.

Adolescent↗
PubMed1993

Clinical significance of late potential in patients with Duchenne muscular dystrophy.

The relationship between late ventricular potentials (LP) and myocardial ischemic changes or ventricular arrhythmias was investigated in patients with Duchenne muscular dystrophy (DMD). Twenty-six DMD patients aged 10-33 years (mean 18.2 years) and 27 age-matched healthy volunteers were studied. Ventricular arrhythmias were detected by 24-h Holter ECGs and LPs were determined using signal-averaged ECGs. In DMD patients filtered QRS duration, late duration, and low-amplitude signal under 40 microV were significantly prolonged compared with those of the controls. The root mean square voltage of the f-QRS complex in the last 40 ms was lower in DMD patients than in the controls. None of the control subjects had LP. However, LP was detected in 8 (31%) of the 26 DMD patients. The patients with LP had more frequent ST-T depression and ventricular arrhythmias than the patients without LP. LP had 60% sensitivity and 87% specificity for documented ventricular arrhythmias. It is concluded that LP in DMD patients indicates the presence of substrate for ventricular arrhythmias associated with local myocardial fibrosis, and is useful in identifying those at high risk for malignant ventricular arrhythmias.

Adolescent↗
PubMed1993

Hyperuricaemia in cyanotic congenital heart disease.

This study examines the exacerbating factors of hyperuricaemia in patients with cyanotic congenital heart disease (CCHD). We studied 59 CCHD patients aged 1 month-30 years. The following variables were assessed: serum uric acid levels, red blood cell count, haemoglobin, hematocrit, partial oxygen pressure and arterial oxygen saturation. Uric acid excretion and renal function were also measured in ten patients with serum levels of uric acid greater than 8 mg/dl (hyperuricaemia group). Serum uric acid level correlated significantly with age and severity of polycythaemia. However, it did not correlate with partial oxygen pressure or arterial oxygen saturation. Uric acid excretion was measured in hyperuricaemia group. Urinary uric acid excretion (24 h) was within normal limits in infants but markedly lower in patients over 15 years of age. The aetiology of hyperuricaemia and decreased uric acid fractional excretion and clearance in infants appears to be secondary to diminished excretion of uric acid in concert with uric acid overproduction. Hyperuricaemia in adolescents and adults with CCHD, however, results mainly from age-related impairment of uric acid excretion.

Acetylglucosaminidase↗
PubMed1993

Occurrence of primary biliary cirrhosis, CREST syndrome and Sjögren's syndrome in a patient with HTLV-I-associated myelopathy.

We report the occurrence of three autoimmune diseases (primary biliary cirrhosis, CREST syndrome and Sjögren's syndrome) in a patient with HTLV-I-associated myelopathy (HAM). The patient had the depressed cell-mediated immune responses but the infiltration of CD8-T cells was found in the cerebrospinal fluid and liver. The clinical and immunological features of this case are similar to those of chronic graft-versus-host disease.

Biopsy↗
PubMed1993

Cerebrospinal fluid interferon-gamma is increased in HTLV-I-associated myelopathy.

Serum and cerebrospinal fluid (CSF) levels of interferon-gamma (IFN-gamma) were assayed with an immunoenzymetric method in 16 patients with HTLV-I-associated myelopathy (HAM). IFN-gamma levels were elevated in serum of two patients and in CSF of nine. Although there was no significant association between the clinical features and the CSF IFN-gamma levels, the mean levels of CSF IgG and CSF anti-HTLV-I antibody titer were higher in patients with elevated CSF IFN-gamma levels than in those with normal CSF IFN-gamma levels.

Adult↗
PubMed1993

Potential role of thymoma and other mediastinal tumors in the pathogenesis of myasthenia gravis.

Ten non-myasthenic thymoma patients and 12 patients with other mediastinal tumors were compared with 19 myasthenic thymoma patients with regard to an increase in circulating CD4+CD8+ cells and the presence of anti-acetylcholine receptor and anti-skeletal muscle antibodies. Although seven non-myasthenic thymoma patients showed positive results, the proportion of myasthenic thymoma patients who were positive for more than one parameter was significantly larger than that of non-myasthenic thymoma patients (89% vs. 40%). Moreover, one patient with a non-thymomatous mediastinal tumor showing a high CD4+CD8+ cell level had a recent history of seronegative myasthenia gravis. The results indicate that measurements of these parameters may predict the risk of the development of MG in patients with thymoma and other mediastinal tumors.

Adult↗
PubMed1993

Granulocyte-macrophage colony-stimulating factor and interleukin-1 increase in cerebrospinal fluid, but not in serum, of HTLV-I-associated myelopathy.

Based on our previous finding of elevated interferon-gamma levels in the cerebrospinal fluid (CSF), but not in serum, of HTLV-I-associated myelopathy (HAM), we assayed serum and CSF levels of granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-1 (IL-1) and tumor necrosis factor-alpha (TNF-alpha) in 20 HAM. GM-CSF and IL-1 also increased only in the CSF in 75% and 35%, respectively, of 20 HAM. TNF-alpha was not detected in any of the sera and CSFs. Multiple cytokines may be produced in the central nervous system and play an important role in HAM.

Adult↗
PubMed1993

Formation and maturation of synapses in primary cultures of rat cerebral cortical cells: an electron microscopic study.

Cerebral cortical cells from fetal rats (18 days) were cultured for 3, 7, 14, 21, 28, 35 days in vitro (DIV) and the development of synapses was examined morphologically by electron microscopy. At 3 DIV, no synapses could be recognized. An immature type of synapse was found at 7 DIV which thereafter developed morphologically. The length of the synaptic contact zone (SCZ) increased with DIV from 271 +/- 11.4 nm (mean +/- SEM) at 7 DIV to 410 +/- 11.4 nm at 35 DIV. The number of synaptic vesicles per terminal also increased with DIV: 10.0 +/- 1.2 at 7 DIV, 35.7 +/- 3.4 at 21 DIV, and 53.3 +/- 4.5 at 35 DIV. The time course of numerical density of synapses was examined quantitatively by electron microscopy. Synaptic density was very low at 7 DIV. It was significantly increased at 14 DIV and thereafter showed variable changes. Four culture series showed decreases after 14 DIV, but one series showed a further increase at 21 DIV followed by a decrease at 28 DIV. The mean density of synapses at each DIV was as follows: 1780 +/- 86/10(6) microns3 at 7 DIV, 4244 +/- 595/10(6) microns3 at 14 DIV, 2285 +/- 674/10(6) microns3 at 21 DIV, 2552 +/- 646/10(6) microns3 at 28 DIV, and 2080 +/- 532/10(6) microns3 at 35 DIV. Neuronal cell density was counted in each culture to calculate the relative number of synapses per neuron. The cell density decreased with age from 301 +/- 51/10(6) microns3 at 7 DIV to 39 +/- 9/10(6) microns3 at 35 DIV.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Brainstem involvement in infantile spasms: a study employing brainstem evoked potentials and magnetic resonance imaging.

Ten patients with infantile spasms underwent brainstem evoked potentials and magnetic resonance imaging (MRI) examination to evaluate brainstem involvement. Short latency somatosensory evoked potentials and auditory brainstem responses were abnormal in seven and five of the 10 patients, respectively. MRI findings were abnormal in nine of the 10 patients. Six patients demonstrated various degrees of atrophy of the brainstem. In all of these cases brainstem evoked potentials were abnormal. This study demonstrates that infantile spasms are frequently associated with brainstem dysfunction and raises the hypothesis that brain atrophy involving the brainstem might be a cause of infantile spasms. In addition, this study also documents the combination of brainstem evoked potentials and MRI examination is valuable tool in the evaluation of brainstem involvement in infantile spasms.

Adrenocorticotropic Hormone↗
PubMed1993

Early changes in second messenger but not receptor binding sites after acute subdural hematoma: an in vitro autoradiographic study.

Neurotransmitter receptor-coupled mechanisms have been recently recognized as important determinants of cell damage after central nervous system (CNS) trauma and ischemia. Many of these receptors exert their intracellular effects via second messenger systems. This study used in vitro autoradiographic radioligand binding to measure beta-adrenergic and muscarinic cholinergic receptors and adenylate cyclase and protein kinase C (PKC) binding sites two h after acute subdural hematoma in rats. Both beta-adrenergic and cholinergic receptor binding sites were unchanged in comparison to controls, while adenylate cyclase binding significantly decreased in the ischemic cortex under the hematoma. These changes may constitute a major limiting factor on receptor-linked therapeutic strategies in trauma and ischemia. Protein kinase C activation significantly increased in the ischemic area under the hematoma in these studies. This appears to be a response to calcium flux, which may be in part glutamate mediated.

Adenylyl Cyclases↗
PubMed1993

The effect of fasting and exogenous adenosine on ATP tissue concentration and viability of canine pancreas grafts during preservation by the two-layer method.

We have demonstrated a direct correlation between a high ATP level in a canine pancreas graft after preservation by the two-layer method and good posttransplant outcome. The purpose of this study was to examine the effect of fasting and exogenous adenosine on the ATP tissue level and viability of the canine pancreas graft during preservation by the two-layer method. Graft viability was judged by graft survival following autotransplantation. Maintenance of normoglycemia for 5 days post-transplant was considered graft survival. The pancreas was harvested from either 72-hr-fated (n = 3) or -fed dogs (n = 4) and preserved by the two-layer (Euro-Collins' solution [EC]/perfluorochemical [PFC]) method for 24 hr. Graft survival rates in fed and fasted groups were 4/4 (100%) and 3/3 (100%), respectively. There was no significant difference in ATP tissue concentrations between the two groups (7.48 +/- 0.55 vs. 7.03 +/- 0.74 mumol/g dry wt, NS). The pancreas was subjected to 60 min warm ischemia and then was preserved by the two-layer method using EC or EC containing 5 mM adenosine for 24 hr. Without adenosine, graft survival rate was 0/3 (0%) and ATP tissue levels were not changed during preservation (1.62 +/- 0.26 vs. 1.56 +/- 0.40 mumol/g dry wt, NS). However, provision of adenosine to the graft during preservation led to the restoration of ATP tissue levels (1.90 +/- 0.54 vs. 8.13 +/- 0.98 mumol/g dry wt, P < 0.01) in 4 of 5 grafts, and these grafts functioned immediately and maintained normoglycemia after transplantation. Graft survival rate was 4/5 (80%). One of 5 grafts, however, did not survive, and the ATP tissue level was not adequately recovered during preservation compared with viable grafts (3.67 vs. 8.13 +/- 0.98 mumol/g dry wt). This study clearly demonstrates that the nutritional state of the donor has no influence on the ATP tissue level and viability of the graft during 24-hr preservation by the two-layer method. On the other hand, provision of adenosine to the graft during preservation stimulates ATP synthesis and improves the viability of the ischemically damaged pancreas.

Adenosine↗
PubMed1993

Successful extended preservation of ischemically damaged pancreas by the two-layer (University of Wisconsin solution/perfluorochemical) cold storage method.

We have demonstrated that a two-layer (University of Wisconsin solution [UW]/perfluorochemical [PFC]) cold storage method restores the function of ischemically damaged pancreas during 24-hr preservation in canine autotransplantation model. The purpose of this study was to examine the possibility of a long-term preservation of the ischemically damaged pancreas by the two-layer (UW/PFC) method. After 60 or 90 min of warm ischemic time, pancreas grafts were preserved by the two-layer (UW/PFC) method or a simple cold storage in UW alone for up to 96 hr. A K value of i.v. glucose tolerance test more than 1.0 2 weeks after autotransplantation was considered successful preservation. After 60 min warm ischemia, limitation of preservation time by the simple cold storage in UW was 24 hr (5/5 100% and 0/5 0%; 24- and 48-hr preservation, respectively). However, the two-layer method made it possible to extend the preservation time up to 48 hr (5/5 100%, 5/5 100%, 2/5 40%, and 0/5 0%; 24-, 48-, 72-, and 96-hr preservation, respectively). After 90 min warm ischemia, the simple cold storage in UW was not effective even for 24-hr preservation (0/5 0%). However, 48-hr preservation was successful by the two-layer (UW/PFC) method (5/5 100%, 5/5 100%, and 0/5 0%; 24-, 48-, and 72-hr-preservation, respectively). After preservation by the two-layer (UW/PFC) method, ATP tissue concentrations of viable grafts were significantly higher compared with nonviable grafts (9.11 +/- 3.05 (n = 22) versus 5.22 +/- 1.02 (n = 13) mumol/g dry wt, P < 0.001). Based on analysis of individual ATP for each graft, if an ATP concentration of 6.0 mumol/g dry weight was determined as a critical value for doing the transplant, sensitivity, specificity, positive predictive value, and negative predictive value were 100%, 84.6%, 91.7%, and 94.3%, respectively. This study clearly demonstrated that 48-hr preservation of the canine pancreas subjected to either 60 or 90 min warm ischemia was successfully achieved by the two-layer (UW/PFC) cold storage method, and ATP tissue concentration at the end of preservation by this method would predict the post-transplant outcome of the ischemically damaged pancreas just prior to transplantation.

Adenosine↗