Search PubMed⌕ Search

Biomedical subjects

M Yanase

Publications and source records attributed to M Yanase.

At least 37 records · Page 2Linked to original sources
PubMed1997

Cyclodextrins are not the major cyclic alpha-1,4-glucans produced by the initial action of cyclodextrin glucanotransferase on amylose.

The initial action of cyclodextrin glucanotransferase (CGTase, EC 2.4.1.19) from an alkalophilic Bacillus sp. A2-5a on amylose was investigated. Synthetic amylose was incubated with purified CGTase then terminated in the very early stage of the enzyme reaction. When the reaction mixture was treated with glucoamylase and the resulting glucoamylase-resistant glucans were analyzed with high performance anion exchange chromatography, cyclic alpha-1,4-glucans, with degree of polymerization ranging from 9 to more than 60, in addition to well known alpha-, beta-, and gamma-cyclodextrin (CD), were detected. The time-course analysis revealed that larger cyclic alpha-1, 4-glucans were preferentially produced in the initial stage of the cyclization reaction and were subsequently converted into smaller cyclic alpha-1,4-glucans and into the final major product, beta-CD. CGTase from Bacillus macerans also produced large cyclic alpha-1, 4-glucans except that the final major product was alpha-CD. Based on these results, a new model for the action of CGTase on amylose was proposed, which may contradict the widely held view of the cyclization reaction of CGTase.

Amylose↗
PubMed1997

Occipitocervical fusion with C1 laminectomy in children.

STUDY DESIGN: Eight children in whom atlantoaxial dislocation had developed underwent occipitocervical fusion using a rectangular rod. The postoperative results are presented, and the postoperative growth and deformation of the cervical spine were determined radiographically. OBJECTIVES: To investigate in a relatively long-term follow-up study whether occipitocervical fusion affects the growth of the cervical spine and induces spinal deformation. SUMMARY OF BACKGROUND DATA: It has been reported that children who have undergone C1-C2 posterior fusion are likely to develop abnormal curvature or deformation of the cervical spine as a result of a disturbance of growth of the fused vertebrae. There have been no studies, however, to confirm that these changes occur after occipitocervical fusion in children. METHODS: The subjects were one boy and seven girls who had undergone occipitocervical posterior fusion during childhood. The average age at the time of surgery was 8.3 years, and the average follow-up period was 5.9 years. The following were assessed radiographically: redislocation of the atlas, bone union, changes in the curvature of the cervical spine, the height and width of the vertebral bodies, and the anteroposterior diameter of the spinal canal. RESULTS: Solid bone union was achieved in all patients with maintenance of the reduced position at the time of surgery. None of the patients exhibited abnormal curvature of the cervical spine. The rate of increase in height of the C2 vertebral body was significantly less than that of vertebral bodies below C3. The rate of increase in width of the vertebral body and the anteroposterior diameter of the spinal canal of the C2 vertebral body and vertebral bodies below C3 did not differ significantly. CONCLUSIONS: Occipitocervical fusion with a rectangular rod is useful for treating atlantoaxial dislocation in children and yields excellent results because of the firm internal fixation it achieves. This surgery induced no apparent postoperative spinal deformations.

Atlanto-Axial Joint↗
PubMed1997

Intracellular hyperthermia for cancer using magnetite cationic liposomes: ex vivo study.

Heating properties of magnetite cationic liposomes (MCL) were investigated in ex vivo experiments using implanted cell pellets. The cell pellets, which consisted of rat glioma T9 cells into which MCL had been incorporated in a petri dish, were implanted subcutaneously in the left femoral region of female F344 rats. The rats were placed in a magnetic field generating coil and irradiated with an alternating magnetic field (384 Oe, 118 kHz) for 60 min. The cell pellets were heated to over 43 degrees C by MCL in the magnetic field, but other body parts of the rats were not heated. After 3 cycles of magnetic heating, all glioma cells were killed and no tumor take was observed.

Animals↗
PubMed1997

Serum transforming growth factor-alpha level can be a parameter for evaluating liver regeneration after partial hepatectomy in patients with liver cancer.

Sensitive and reliable laboratory parameters are necessary to evaluate the degree of liver regeneration serially in patients after partial hepatectomy for liver cancer. We evaluated the serum levels of transforming growth factor-alpha (TGF-alpha) and hepatocyte growth factor (HGF), both of which are potent mitogens for hepatocytes, in 22 hepatectomized patients with liver cancer: 10 patients with hepatocellular carcinoma and 12 patients with metastatic liver tumors. Ten patients who underwent laparotomy for nonhepatic surgery were also studied as surgical controls. The serum TGF-alpha and HGF levels were measured by sandwich enzyme-linked immunosorbent assay techniques. Both the serum TGF-alpha and HGF levels increased after partial hepatectomy. However, there was no correlation between the levels of TGF-alpha and HGF. The maximal level of TGF-alpha achieved in each case correlated significantly with the resected liver volume and the increased volume of the remaining liver. Hepatocyte growth factor showed no such correlations. After nonhepatic surgery, the HGF level also increased significantly, while the TGF-alpha level did not. These results suggest that the serum TGF-alpha level varies depending on the regenerative stimulus to the liver, and that its increase corresponds with the degree of liver regeneration that occurs in patients after partial hepatectomy for liver cancer. In contrast, it is unlikely that the serum HGF level reflects liver regeneration. In conclusion, the serum TGF-alpha level can be used as a parameter for evaluating liver regeneration in patients who have undergone partial hepatectomy.

Carcinoma, Hepatocellular↗
PubMed1996

Controlling substrate preference and transglycosylation activity of neopullulanase by manipulating steric constraint and hydrophobicity in active center.

The substrate specificity and the transglycosylation activity of neopullulanase was altered by site-directed mutagenesis on the basis of information from a three-dimensional structure predicted by computer-aided molecular modeling. According to the predicted three-dimensional structure of the enzyme-substrate complex, it was most likely that Ile-358 affected the substrate preference of the enzyme. Replacing Ile-358 with Trp, which has a bulky side chain, reduced the acceptability of alpha-(1-->6)-branched oligo- and polysaccharides as substrates. The characteristics of the I358W-mutated enzyme were quite different from those of wild-type neopullulanase and rather similar to those of typical starch-saccharifying alpha-amylase. In contrast, replacing Ile-358 with Val, which has a smaller side chain, increased the preference for alpha-(1-->6)-branched oligosaccharides and pullulan as substrates. The transglycosylation activity of neopullulanase appeared to be controlled by manipulating the hydrophobicity around the attacking water molecule, which is most likely used to cleave the glucosidic linkage in the hydrolysis reaction. We predicted three residues, Tyr-377, Met-375, and Ser-422, which were located on the entrance path of the water molecule might be involved. The transglycosylation activity of neopullulanase was increased by replacing one of the three residues with more hydrophobic amino acid residues; Y377F, M375L, and S422V. In contrast, the transglycosylation activity of the enzyme was decreased by replacing Tyr-377 with hydrophilic amino acid residues, Asp or Ser.

Amino Acid Sequence↗
PubMed1996

Potato D-enzyme catalyzes the cyclization of amylose to produce cycloamylose, a novel cyclic glucan.

Potato D-enzyme was purified from recombinant Escherichia coli, and its action on synthetic amylose (average Mr of 320,000) was analyzed. D-enzyme treatment resulted in a decrease in the ability of the amylose to form a blue complex with iodine. Analysis of the products indicated that the enzyme catalyzes an intramolecular transglycosylation reaction on amylose to produce cyclic alpha-1,4-glucan (cycloamylose). Confirmation of the cyclic structure was achieved by demonstrating the absence of reducing and nonreducing ends, resistance to hydrolysis by glucoamylase (an exoamylase), and by "time of flight" mass spectrometry. The degree of polymerization of cycloamylose products was determined by time of flight mass spectrometry analysis and by high-performance anion-exchange chromatography following partial acid hydrolysis of purified cycloamylose molecules and was found to range from 17 to several hundred. The yield of cycloamylose increased with time and reached >95%. D-enzyme did not act upon purified cycloamylose, but if glucose was added as an acceptor molecule, smaller cyclic and linear molecules were produced. The mechanism of the cyclization reaction, the possible role of the enzyme in starch metabolism, and the potential applications for cycloamylose are discussed.

Chromatography, Gel↗
PubMed1996

Indication of fusion for lumbar spinal stenosis in elderly patients and its significance.

STUDY DESIGN: Selection of surgical therapy for lumbar canal stenosis in elderly patients is discussed. Decompression alone and decompression with fusion were evaluated. OBJECTIVES: To determine the indication of decompression with fusion for lumbar spinal stenosis in elderly patients. SUMMARY OF BACKGROUND DATA: Although there is no objection to posterior decompression, which is regarded as the first choice of surgical therapy for lumbar spinal stenosis in the elderly, it is debatable whether or not fusion should be used with decompression. METHODS: The presence or absence of instability was defined by Posner's method from preoperative plain radiographic lateral findings. Thirty-four elderly patients with lumbar canal stenosis were studied. Seventeen of the 34 patients were found to have instability. Ten of the 17 patients with spinal instability underwent decompression and instrumented fusion. The seven remaining patients with spinal instability underwent decompression alone. The 17 patients without spinal instability were treated by decompression alone. Preoperative symptoms, postoperative results, and changes in radiographic findings were compared among the three groups. RESULTS: The group treated by decompression and fusion showed the best results. The group treated by decompression in the presence of instability showed the worst results by the Japanese Orthopaedic Association back scores. Good results can be obtained by decompression alone only if the patients do not have instability as defined by Posner. CONCLUSIONS: The definition of instability by Posner's method proved useful for selecting elderly patients with instability for fusion treatment. Fusion with instrumentation should be performed on elderly patients with instability after decompression.

Aged↗
PubMed1996

Intracellular hyperthermia for cancer using magnetite cationic liposomes: in vitro study.

'Magnetite cationic liposomes (MCL)' were developed as a means to generate intracellular hyperthermia. Affinity of the MCL to glioma cells was ten times higher than that of magnetite 'neutral' liposomes due to the electrostatic interaction based on the positive charge of the MCL. Heat generation of the MCL was studied using agar phantoms and small pellets of rat glioma cells. When a high-frequency magnetic field, 118 kHz, 384 Oe was applied to glioma cells in the presence of MCL, the glioma cell pellet of 80 microl (5.4 mm in diameter) was heated to over 43 degrees C and all the cells died after 40 min irradiation owing to the hyperthermic effect. The terminal temperature of the cell pellet was proportional to the pellet volume when other parameters were constant. It thus appears that the MCL can heat a tumor of more than 80 microl in volume to above 42 degrees C.

Adsorption↗
PubMed1996

Inhibitors of acyl-CoA: cholesterol acyltransferase. II. Preparation and hypocholesterolemic activity of optically active dibenz[b,e]oxepin-11-carboxanilides.

In a previous paper, we reported a novel inhibitor of acyl-CoA: cholesterol acyltransferase (ACAT), 2-bromo-N-(2,6-diisopropylphenyl)-6,11- dihydrodibenz[b,e]oxepin-11-carboxamide (1). In this work, we prepared both enantiomers and tested them for ability to inhibit ACAT (liver microsomes from cholesterol-fed rabbits) in vitro and to decrease serum total cholesterol in cholesterol-fed golden hamsters in vivo. The precursor carboxylic acid 4 was optically resolved with cinchonidine. The obtained (-)- and (+)-4 were converted to (-)- and (+)-1 without racemization, respectively. The enantiomer (-)-1 showed potent ACAT inhibitory activity in vitro with an IC50 value of 8 nM and was approximately 10-fold more active than (+)-1. Furthermore, (-)-1 showed strong hypocholesterolemic activity in vivo, whereas (+)-1 was inactive. A molecular modeling study showed that the difference of ACAT inhibitory activity between the enantiomers was derived from the spatial alignment of the bromine. Compound (-)-1 was selected for further evaluation as KW-3033.

Animals↗
PubMed1995

MRI findings in patients with a cervical spinal cord injury who do not show radiographic evidence of a fracture or dislocation.

We investigated the usefulness of magnetic resonance imaging (MRI) in assessing cervical spinal cord injury in patients where there was no evidence of bone injury on radiographs, and examined the relationship between the MRI findings and the clinical prognosis of this injury. MRI allowed us to confirm directly the cause and severity of spinal cord compression in 30 of 31 cases. The patients with severe spinal cord compression demonstrated by MRI showed poor neurological improvement. In regard to the signal changes in the spinal cord, the patients who showed no signal change on T1- and T2-weighted images had a better prognosis. MRI is a very useful non-invasive adjunctive imaging modality for diagnosis of this injury and for the evaluation of the compressed spinal cord. It also demonstrates potential in predicting neurological recovery.

Adult↗
PubMed1995

Transpedicular fixation of the lumbar and lumbosacral spine with screws. Application of the Diapason system.

Forty-six patients with the Diapason transpedicular screw system for lumbar and lumbosacral fusions were analysed clinically. No implant breakage was observed, but one rod migrated. Additional sacral screws different in the length of the threaded portion are necessary in this system. Metallosis was noted in a few cases, but posed no significant clinical problems. This system, which is simple in structure, easy to use, and applicable to magnetic resonance scanning after surgery, is considered to be a useful instrumentation.

Adolescent↗
PubMed1995

Lobar dysmorphism of the kidney.

We report a case of a 38-year-old woman with lobar dysmorphism of the kidney. Lobar dysmorphism is a pathology classified under renal pseudotumor, which has received little attention. It is presumed that these cases will increase in number with advances in imaging diagnosis. Dynamic CT scan is useful for the diagnosis of this disease.

Adult↗
PubMed1995

A case of Gartner's duct cyst with a right aplastic kidney.

We report a case of a Gartner's duct cyst with a right aplastic kidney. This was discovered when the right kidney was not identified in an examination for epigastric pain. CT and MRI proved useful in the diagnosis. An MRI showed a tubular structure ascending from the cyst and a complication of a bicornate uterus. As the patient was asymptomatic, the patient was followed without treatment.

Child↗
PubMed1995

Role of N-methyl-D-aspartate receptor in acute spinal cord injury.

To clarify the role of N-methyl-D-aspartate (NMDA) receptors in acute spinal cord injury, changes in the intraspinal microcirculation after acute spinal cord injury in rabbits were examined. Systemic administration of MK-801, an NMDA receptor antagonist, at a dose of 5 mg/kg, significantly improved motor recovery after injury and significantly reduced edema formation at the injured site without altering spinal cord blood flow or vascular permeability at the injured site. These findings indicate that excitatory amino acids contribute to secondary spinal cord damage, especially edema formation, mediated by NMDA receptors in the early stage after injury.

Acute Disease↗
PubMed1995

Cytokines modulate in vitro invasiveness of renal cell carcinoma cells through action on the process of cell attachment to endothelial cells.

Cytokines play important roles in adhesion between various cells and endothelium. Cell-cell adhesion is also a critical step in the invasion of interstitial tissue by cancer cells. Using an in vitro invasion assay modified by cultured human umbilical venule endothelial cells (HUVEC) and an extracellular matrix (Matrigel) membrane system, we studied how cytokines affect the invasiveness of human renal cell carcinoma cells through action on the endothelium. When HUVEC were treated for 6 hours with tumor necrosis factor (TNF, 100 or 1000 U/ml.), interleukin-1 (IL-1, 10 ng./ml.) or IL-6 (1.0 or 10 ng./ml.), the treatment significantly increased in vitro invasiveness of the carcinoma cells. Enhancement of carcinoma cell invasiveness reflected the enhancement by the cytokine treatments of the ability of HUVEC to express vascular cell adhesion molecule-1 (VCAM-1). Application of anti-VCAM-1 monoclonal antibody (mAb) suppressed in vitro invasion of the carcinoma cells when HUVEC were treated with the cytokines at the above concentrations. Moreover, an adherence assay demonstrated that a larger number of carcinoma cells adhered to the endothelium treated by the cytokines than to endothelium not receiving such treatment and that anti-VCAM-1 mAb application inhibited the adhesion. The cytokine treatment of HUVEC did not affect type IV collagenolysis. These results indicated that cytokines can enhance the in vitro invasiveness of carcinoma cells through their action on endothelium (that is, augmentation of VCAM-1 expression) in the in vitro invasion assay modified with HUVEC-Matrigel-reconstituted membrane.

Antibodies, Monoclonal↗
PubMed1995

A rare case of disseminated intravascular coagulation caused by the nonionic contrast medium iohexol.

Nonionic contrast media are reported to cause serious adverse reactions less often than ionic contrast media. However, we treated an otherwise healthy woman with a left ureteral stone in whom disseminated intravascular coagulation developed due to intravenous administration of the nonionic contrast medium iohexol. We discuss the clinical course and possible causes of disseminated intravascular coagulation. Our case emphasizes that nonionic contrast media are not free from serious adverse reactions although the incidence seems extremely low.

Disseminated Intravascular Coagulation↗
PubMed1994

Inhibitors of acyl-CoA:cholesterol acyltransferase. 1. Synthesis and hypocholesterolemic activity of dibenz[b,e]oxepin-11-carboxanilides.

A series of N-phenyl-6,11-dihydrodibenz[b,e]oxepin-11-carboxamides and related derivatives were prepared on the basis of structures of the reported inhibitors of acyl-CoA:cholesterol acyltransferase (ACAT). These compounds were tested for their ability to inhibit ACAT (liver microsomes from cholesterol-fed rabbits) in vitro and to decrease serum total cholesterol in cholesterol-fed golden hamsters in vivo. The structure-activity relationships in vitro were as follows. Substitution at positions 2 and 6 in the anilide resulted in potent inhibitory activity, and the potency increased with increasing size of the substituents, with maximum potency being obtained with a 2,6-diisopropyl substitution. The position of the substituent on the dibenz[b,e]oxepin ring system influenced the activity, and substitution at position 2 was critical for potent activity. The electronic effect of the substituent at position 2 does not influence activity, but bulkiness seems to be a significant factor. The lipophilicity of the compounds also plays an important role in determining ACAT inhibitory activity. Among the compounds tested, 2-bromo-N-(2,6-diisopropylphenyl)-6,11-dihydrodibenz-[b,e]++ +oxepin-11- carboxamide (33, KF17828) showed significant in vitro activity (rabbit liver microsomes IC50 = 23 nM) and the most potent in vivo activity (complete reduction in elevated serum total cholesterol levels at a dose of 10 mg/kg in hamsters).

Animals↗