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R Hayashi

Publications and source records attributed to R Hayashi.

At least 37 records · Page 2Linked to original sources
PubMed2001

Structural and functional changes in bovine pancreatic ribonuclease a by the replacement of Phe120 with other hydrophobic residues.

To clarify the specific role of Phe120 in bovine pancreatic ribonuclease A (RNase A), changes in the thermal stability and activity of F120L, F120A, F120G, and F120W were analyzed with respect to some thermodynamic terms, i.e., Gibbs free energy, enthalpy, and entropy. The structural destabilization of F120L, F120A, and F120G was due to a decrease in DeltaH(m) with a parallel decrease in amino-acid volume at position 120, while the destabilization of F120W can be ascribed to an increase in DeltaS(m) accompanying an increase in DeltaH(m), showing that the size of Phe120 produces an optimum balance of conformational enthalpy and entropy for achieving the maximal structural stability. Moreover, the replacement of Phe120 affects activity. The increase in K(m) showed that the hydrophobicity and pi electron of Phe120 are important factors in substrate binding. The decrease in k(cat) was predicted to be due to positional changes of the side chains of His12 and/or His119. The positional changes were successfully detected by the rate of carboxymethylation by iodoacetate or bromoacetate, which correlated very well with decreases in activity, supporting the view that Phe120 also plays an important role in determining the position of His12 and/or His119 in order to achieve efficient catalysis.

Acetates↗
PubMed2001

Ionizing radiation enhances matrix metalloproteinase-2 production in human lung epithelial cells.

Radiation pneumonitis is a major complication of radiation therapy. However, the detailed cellular mechanisms have not been clearly defined. Based on the recognition that basement membrane disruption occurs in acute lung injury and that matrix metalloproteinase (MMP)-2 can degrade type IV collagen, one of the major components of the basement membrane, we hypothesized that ionizing radiation would modulate MMP-2 production in human lung epithelial cells. To evaluate this, the modulation of MMP-2 with irradiation was investigated in normal human bronchial epithelial cells as well as in A549 cells. We measured the activity of MMP-2 in the conditioned medium with zymography and the MMP-2 mRNA level with RT-PCR. Both of these cells constitutively expressed 72-kDa gelatinolytic activity, corresponding to MMP-2, and exposure to radiation increased this activity. Consistent with the data of zymography, ionizing radiation increased the level of MMP-2 mRNA. This radiation-induced increase in MMP-2 expression was mediated via p53 because the p53 antisense oligonucleotide abolished the increase in MMP-2 activity as well as the accumulation of p53 after irradiation in A549 cells. These results indicate that MMP-2 expression by human lung epithelial cells is involved in radiation-induced lung injury.

Antisense Elements (Genetics)↗
PubMed2001

Optically active antifungal azoles. XII. Synthesis and antifungal activity of the water-soluble prodrugs of 1-[(1R,2R)-2-(2,4-difluorophenyl)-2-hydroxy-1-methyl-3-(1H-1,2,4-triazol-1-yl)propyl]-3-[4-(1H-1-tetrazolyl)phenyl]-2-imidazolidinone.

1-[(1R,2R)-2-(2,4-Difluorophenyl)-2-hydroxy-1-methyl-3-(1H-1,2,4-triazol-1-yl)propyl]-3-[4-(1H-1-tetrazolyl)phenyl]-2-imidazolidinone (1: TAK-456) was selected as a candidate for clinical trials, but since its water-solubility was insufficient for an injectable formulation, the quaternary triazolium salts 2 were designed as water-soluble prodrugs. Among the prodrugs prepared, 4-acetoxymethyl-1-[(2R,3R)-2-(2,4-difluorophenyl)-2-hydroxy-3-[2-oxo-3-[4-(1H-1-terazolyl)phenyl]-1-imidazolidinyl]butyl]-1H-1,2,4-triazolium chloride (2a: TAK-457) was selected as an injectable candidate for clinical trials based on the results of evaluations on solubility, stability, hemolytic effect and in vivo antifungal activities.

Alkylation↗
PubMed2001

Functional and structural roles of constituent amino acid residues of bovine pancreatic ribonuclease A.

In protein engineering, wherein the goal is desirable function and high conformational stability, the characteristics of each constituent amino acid residue are important, in terms of the overall characteristics of the target protein. Bovine pancreatic riobonuclease A (RNase A) is, historically, one of the most intensively analyzed proteins, and a considerable amount of information is available on amino acid-level information. Such data would serve to aid the understanding of relationships between the distribution of various amino acid residues in the protein molecule and the unique structure and/or functions of RNase A. This review summarizes the thus-far clarified roles of 38 of the total 124 amino acid residues which comprise RNase A, with respect to protein function, stability, and folding.

Journal Article↗
PubMed2001

Substrate recognition mechanism of carboxypeptidase Y.

To clarify the substrate-recognition mechanism of carboxypeptidase Y, Fmoc-(Glu)n Ala-OH (n = 1 to 6), Fmoc-(Glu)n Ala-NH2 (1 to 5), and Fmoc-Lys(Glu)3Ala-NH2 were synthesized, and kinetic parameters for these substrates were measured. Km for Fmoc-peptides significantly decreased as peptide length increased from n = 1 to n = 5 with only slight changes in kcat. Km for Fmoc-(Glu)(5,6)Ala-OH were almost the same as one for protein substrates described previously (Nakase et al., Bull. Chem. Soc. Jpn., 73, 2587-2590). These results show that the enzyme has six subsites (S1' and S1-S5). Each subsite affinity calculated from the Km revealed subsite properties, and from the differences of subsite affinity between pH 6.5 and 5.0, the residues in each subsite were predicted. For Fmoc-peptide amide substrates, the priorities of amidase and carboxamide peptidase activities were dependent on the substrate. It is likely that the interactions between side chains of peptide and subsites compensate for the lack of P1'-S1' interaction, so the amidase activity prevailed for Fmoc-(Glu)(3,5)Ala-NH2. These results suggest that these subsites contribute extensively to substrate recognition rather than a hydrogen bond network.

Amino Acid Sequence↗
PubMed2001

Outpatient cocaine abuse treatment: predictors of success.

In 1990 more than 238,000 patients in the United States entered treatment, with cocaine as their primary diagnosis. This represented 36 percent of the treatment admissions for substance abuse. This research project uses data from the U.S. Army's Alcohol and Drug Abuse Prevention and Control Program to analyze which treatment and demographic variables have an effect on cocaine treatment outcomes. The sample included 3602 soldiers entered into treatment between 1983 and 1992 for cocaine abuse. The logistical regression results suggested the following treatment variables had an effect on outcomes: the type of treatment provided, the length of time in treatment, the number of different types of drugs being abused prior to treatment, and the length of time since the patient had abused cocaine prior to entering treatment. Race of the patient had an impact on treatment outcomes, but gender, educational level, age, rank of the soldier, marital status, and length of time in the military did not have an impact on treatment outcomes.

Ambulatory Care↗
PubMed2001

Microvessel density predicts the radiosensitivity of metastatic head and neck squamous cell carcinoma in cervical lymph nodes.

Cervical lymph node metastasis is the most common recurrence pattern of head and neck squamous cell carcinoma (HNSCC), and it is usually treated with radiation therapy and/or neck dissection. There has long been a desire for markers useful in predicting radiosensitivity to enable assignment of patients with recurrent head and neck cancer to clinical trials to improve their survival rates and quality of life. A total of 43 cases of HNSCC treated with whole or elective neck irradiation (total dose, 26-70 Gy; median, 60 Gy) for recurrent metastatic SCC in neck lymph nodes after neck dissection between 1992 and 1999 were the subject of this study. The relationship between radiosensitivity and clinicopathological and histopathological factors, including the Ki-67-labeling index for cell proliferation, p53 immunoreactivity and microvessel density (MVD), in surgical neck lymph node specimens were investigated by univariate and multivariate analysis. Of the 43 patients, 31 had recurrent tumors in neck lymph nodes after radiotherapy. Univariate analysis revealed significant associations between radiosensitivity and both high grade of keratinization (p=0.033) and low MVD (p=0.004), and marginally significant associations between radiosensitivity and grade of differentiation of the cancer in the lymph nodes (p=0.070). Multivariate analysis showed that only MVD had predictive value (p=0.016). Tumors with a high MVD possessed a significantly better neck control rate than tumors with a low MVD (p=0.004) by Kaplan-Meier analysis. MVD can be used as a good predictive marker for radiosensitivity of metastatic HNSCCs in cervical lymph nodes after neck dissection.

Aged↗
PubMed2001

Sensory disturbance of the thigh after renal transplantation.

PURPOSE: Although sensory disturbance of the anterior and/or lateral thigh often develops after renal transplantation, this complication is overlooked because of the minor degree of disability. We evaluated the rate of sensory disturbance of the thigh after renal transplantation. MATERIALS AND METHODS: We examined neurological deficits of the thigh on the operated side in 61 patients who underwent renal transplantation, including 48 using the internal and 13 using the external iliac artery. RESULTS: We noted sensory disturbance in 23 of the 61 cases, including 20 of the 48 in which the internal iliac artery was used. One patient had complete femoral nerve palsy involving motor weakness. Sensory disturbance was in the anterior thigh in 15 patients, in the lateral thigh in 3, and on the anterior and lateral thigh in 2. Postoperatively there was sensory disturbance of the thigh in 3 of the 13 patients in whom the external iliac artery was used. Sensory disturbance persists in all 3 cases at the time of this report, including in the anterior thigh in 1, and in the anterior and lateral thigh in 2. CONCLUSIONS: The rate of sensory disturbance of the thigh after renal transplantation is high. Therefore, we should inform patients of the possibility of sensory disturbance before renal transplantation surgery is performed.

Femoral Nerve↗
PubMed2001

Image analysis of microvessel surface area predicts radiosensitivity in early-stage laryngeal carcinoma treated with radiotherapy.

PURPOSE: The tissue oxygenation level, which is theoretically governed by distance from blood vessels, is one of the most important modulators of the radiosensitivity of carcinoma. A computed image analysis system for the detection of tissue oxygenation was developed to establish a method of predicting radiosensitivity in early-stage laryngeal carcinoma treated by curative radiotherapy. EXPERIMENTAL DESIGN: Microvessel structures labeled with CD31 antigen were investigated in 55 patients undergoing curative radiotherapy for T1 and T2 laryngeal carcinoma. We calculated (a) microvessel density [(MVD) vessels/field] under a microscope; (b) the ratio of the total microvessel number (TN):tumor area (TA) [TN:TA; vessels/mm2]; (c) the ratio of the total microvessel perimeter (TP):TA (TP:TA; mm/mm2); and (d) the ratio of tumor tissue area >150 microm from microvessels (hypoxic ratio; %) as parameters of tissue oxygenation in each whole biopsy specimen by using an image analyzer. We compared each of these factors with radiosensitivity. RESULTS: Mann-Whitney's U test revealed that tumors with a high MVD (median, 42 vessels/field), high TN:TA ratio (median=40.9 vessels/mm2), high TP:TA ratio (median, 2.92 mm/mm2), and low hypoxic ratio (median, 30.3%) had significantly greater radiosensitivity than tumors with a low MVD, low TN:TA ratio, low TP:TA ratio or high hypoxic ratio (P = 0.002, P = 0.0004, P < 0.0001, and P = 0.004, respectively). CONCLUSIONS: Prediction of radiosensitivity on the basis of the TP:TA ratio can be used as an efficient means of avoiding ineffective radiation, complications after salvage surgery, and prolonged hospital stays.

Adult↗
PubMed2001

[A case of polymyositis complicated with pulmonary tuberculosis concerned with steroid resistance due to rifampin administration].

A 63-year-old woman in whom polymyositis had been diagnosed since 1994 was treated with ten mg of prednisolone. In 1998, she contracted pulmonary tuberculosis simultaneously with acute exacerbation of the polymyositis. The polymyositis was then treated with 40 mg of prednisolone, and the pulmonary tuberculosis, with isoniazid (INH), rifampin (RFP) and ethambutol (EB). However, the polymyositis was worsening, possibly because the administration of RFP had induced steroid resistance. Because of this, a large amount of steroid was considered necessary for the treatment of the polymyositis (PSL 80 mg/day). An additional administration of cyclosporine (CyA) made possible a decrease in the amount of steroid given. RFP has a potency to induce the enzyme p450, which has the effect of metabolizing steroids or CyA, thus shortening the half-life of these agents. When a case of polymyositis is superimposed with pulmonary tuberculosis, it should be remembered that RFP may shorten the half-life of any steroid or CyA that is administered as treatment.

Antibiotics, Antitubercular↗
PubMed2000

Cloning of differentially expressed sequence tags from nickel-transformed human embryonic lung cells.

Differential display polymerase chain reaction (DD-PCR) was used to analyze the differentially expressed genes from nickel-transformed human embryonic lung (HEL) cells (MRC-9 and IMR-90) and their control counterparts (non-treated). Two genes, MS515 and IC82, were confirmed by Northern blot analysis. MS515 was detected in control and nickel oxide (NiO)-transformed MRC-9 cells, as well as in non-small cell lung cancer (NSCLC) EBC-1 cells, while very weak expression was observed in nickel subsulfide (Ni(3)S(2))-transformed MRC-9 cells and small cell lung cancer (SCLC) SBC-2 cells. IC82 could not be detected in control IMR-90 cells, while it was expressed in EBC-1 cells and NiO- and Ni(3)S(2)-transformed IMR-90 cells. These findings indicate that individual nickel compounds have their own target gene(s) in inducing lung cancer. Sequencing analyses showed that the MS515 gene shared a high degree of homology (over 80%) with the gene Mena, which is involved in actin polymerization. IC82 showed 99% homology with human chromosome 4 clone C0440E08 and a coding sequence in the brain. The roles of these two genes in nickel carcinogenesis will be discussed.

Base Sequence↗
PubMed2000

Correlation between coefficient of variation of choice reaction time and components of event-related potentials (P300): effect of benzodiazepine.

We studied the relationship between accuracy in the cognitive process and components of event-related potentials (P300) in 21 young and healthy subjects. Benzodiazepine was used to manipulate the cognitive state of the subjects. We recorded the serial changes in P300, choice reaction time (CRT), and error ratio (ER) before and after oral administration of 0.4 mg of alprazolam. After administration, the coefficient of variation of CRT tended to decrease in nine subjects (group I) and increase in 12 subjects (group II). Prolongation of the P300 latency was observed in all subjects after treatment; however, such change was more predominant in group II than in group I. In group I, there was no error and no significant difference in P300 amplitude before and after administration. In group II, alprazolam significantly reduced P300 amplitude and increased ER. Our results suggest that the accuracy and P300 amplitude were preserved when the central nerve system managed to reduce fluctuations in CRT but P300 amplitude diminished and the error ratio increased following deterioration of these processes.

Adult↗
PubMed2000

Transactivation of the multidrug resistance 1 gene by T-cell factor 4/beta-catenin complex in early colorectal carcinogenesis.

The mutational inactivation of a tumor suppressor gene, adenomatous polyposis coli (APC), results in the accumulation of cytoplasmic beta-catenin protein and the activation of T-cell factor (TCF)/lymphoid enhancer factor transcriptional factors. A colorectal carcinoma cell line, DLD-1, was engineered to suppress transactivation by the TCF4/beta-catenin complex in a dominant-negative manner under the strict control of the tetracycline regulatory system. A large-scale comparison of the expression profiles, using two-color fluorescence hybridization of cDNA microarray, led to the identification of MDR1 as a target gene of the TCF4/beta-catenin complex. Luciferase reporter and gel retardation assays revealed the TCF4/beta-catenin responsive elements in the promoter of the human MDR1 gene. Corresponding to the accumulation of beta-catenin, expression of the MDR1 gene product was steadily up-regulated in adenomas and adenocarcinomas of 10 patients with familial adenomatous polyposis. In combination with cell proliferative activities of c-myc and cyclin D1, MDR1 may initiate colorectal tumorigenesis by suppressing cell death pathways programmed in intestinal epithelial cells.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2000

Ras mediates effector pathways responsible for pre-B cell survival, which is essential for the developmental progression to the late pre-B cell stage.

Ras is essential for the transition from early B cell precursors to the pro-B stage, and is considered to be involved in the signal cascade mediated by pre-B cell antigen receptors. To examine the role of p21(ras) in the late stage of B cell differentiation, we established transgenic mice (TG) expressing a dominant-inhibitory mutant of Ha-ras (Asn-17 Ha-ras) in B lineage cells at high levels after the early B cell precursor stage. Expression of p21(Asn-17) (Ha-ras) was associated with a prominent reduction in the number of late pre-B cells, but had little effect on proliferation of early pre-B cells. Inhibition of p21(ras) activity markedly reduced the life span of pre-B cells, due, at least in part, to downregulation of the expression of an antiapoptotic protein, Bcl-xL. Thus, the apparent role for p21(ras) activity in pre-B cell survival may explain the decreased numbers of late pre-B cells in Asn-17 Ha-ras TG. Consistent with this possibility, overexpression of Bcl-2 in Asn-17 Ha-ras TG reversed the reduction in the number of late pre-B cells undergoing immunoglobulin light chain gene (IgL) rearrangement and progressing to immature B cells. These results suggest that p21(ras) mediates effector pathways responsible for pre-B cell survival, which is essential for progression to the late pre-B and immature B stages.

Animals↗
PubMed2000

Characteristics of parkinsonian and ataxic gaits: a study using surface electromyograms, angular displacements and floor reaction forces.

To clarify the characteristics of parkinsonian and ataxic gaits, we analyzed electromyograms (EMGs) of the thigh and leg muscles, angular displacements of the hip and leg joints, and floor reaction forces during free walking for each gait phase in 16 patients with Parkinson's disease (PD) and 14 ataxic patients with cerebellar degenerations. We studied 17 healthy elderly subjects whose walking speed was similar to that of patients with moderate disease. Free walking by PD patients was characterized by low maximum activity of the gastrocnemius/soleus (GC) and tibialis anterior (TA) muscles. Ataxic patients showed high activity of GC and TA during the period when these muscles were not active in normal walking. The ratio of changes of EMG of the distal muscles to changes in angular displacement of the ankle (DeltaEMG/Deltaangle) was reduced in GC of PD patients in ankle dorsiflexion, whereas it was high in GC and TA of ataxic patients in ankle dorsiflexion and plantarflexion, respectively. Changes in DeltaEMG/Deltaangle coincided with those in proprioceptive reflexes reported previously. Our results showed that measurement of EMG for each phase revealed disease-specific factors, and that of DeltaEMG/Deltaangle might be a conventional clue for estimation of reflexes for these gait disorders.

Aged↗
PubMed2000

Gait disturbances in patients with pontine medial tegmental lesions: clinical characteristics and gait analysis.

OBJECTIVE: To determine the clinical characteristics of gait disorders in patients with pontine medial tegmental lesions. DESIGN: We compared features of gait disorders between patients with infarcts in the medial tegmentum and those with stroke in other areas of the pons (pathological control subjects) by measuring electromyographic results of lower limb muscles and several biomechanical parameters. PATIENTS: Two patients with infarcts in the rostral medial tegmentum and 4 control subjects. Two of the control patients had lesions in the pontine base, while the lesions in the other 2 were in the pontine tegmentum and base (combined lesions). RESULTS: Patients with rostral medial tegmental lesions and controls with pontine base lesions showed unstable walking characterized by irregular angular displacements and foot pressures. However, they differed by the following 3 features. (1) Rostral medial tegmental lesions elicited truncal ataxia without limb ataxia. In comparison, pontine base lesions elicited limb ataxia without truncal ataxia and caused hemiparesis. (2) Instability was more severe and persistent in patients with the former lesions than in those with the latter lesions. Slowness of walking speed and prolongation of the double-support period were clearly observed in the former group. (3) Electromyographic changes characteristic of cerebellar ataxia were clearly evident in patients with rostral medial tegmental lesions. The electromyographic amplitudes of the gastrocnemius and tibialis anterior muscles were almost constant throughout the gait cycle, resulting in the disappearance of the inherent periodic pattern of each muscle. CONCLUSION: Medial tegmental lesions in the rostral pons cause prolonged and severe unstable walking that resembles spinocerebellar ataxic pattern, and impairment of the spinocerebellar loop might be the pathomechanism underlying such a gait disturbance.

Aged↗