Biomedical subjects

Koji Hayashi

Publications and source records attributed to Koji Hayashi.

At least 19 recordsLinked to original sources

PubMed2006

Spontaneous recanalization at subacute phase of stroke may be dramatic: A case report.

Spontaneous recanalization of the occluded cerebral arteries has occasionally occurred in an acute phase of stroke patients. We report a stroke patient with recanalization at 7 days of onset detected by using continuous transcranial Doppler (TCD) monitoring. After the presence of microembolic signals on TCD display, dynamic flow changes of the middle cerebral artery (MCA) occurred, which represented recanalization of the occluded MCA.

Adult↗

PubMed2006

Is iliotibial band syndrome really a friction syndrome?

Iliotibial band (ITB) syndrome is regarded as an overuse injury, common in runners and cyclists. It is believed to be associated with excessive friction between the tract and the lateral femoral epicondyle-friction which 'inflames' the tract or a bursa. This article highlights evidence which challenges these views. Basic anatomical principles of the ITB have been overlooked: (a) it is not a discrete structure, but a thickened part of the fascia lata which envelops the thigh, (b) it is connected to the linea aspera by an intermuscular septum and to the supracondylar region of the femur (including the epicondyle) by coarse, fibrous bands (which are not pathological adhesions) that are clearly visible by dissection or MRI and (c) a bursa is rarely present-but may be mistaken for the lateral recess of the knee. We would thus suggest that the ITB cannot create frictional forces by moving forwards and backwards over the epicondyle during flexion and extension of the knee. The perception of movement of the ITB across the epicondyle is an illusion because of changing tension in its anterior and posterior fibres. Nevertheless, slight medial-lateral movement is possible and we propose that ITB syndrome is caused by increased compression of a highly vascularised and innervated layer of fat and loose connective tissue that separates the ITB from the epicondyle. Our view is that ITB syndrome is related to impaired function of the hip musculature and that its resolution can only be properly achieved when the biomechanics of hip muscle function are properly addressed.

Athletic Injuries↗

PubMed2006

Highly accurate genome sequences of Escherichia coli K-12 strains MG1655 and W3110.

With the goal of solving the whole-cell problem with Escherichia coli K-12 as a model cell, highly accurate genomes were determined for two closely related K-12 strains, MG1655 and W3110. Completion of the W3110 genome and comparison with the MG1655 genome revealed differences at 267 sites, including 251 sites with short, mostly single-nucleotide, insertions or deletions (indels) or base substitutions (totaling 358 nucleotides), in addition to 13 sites with an insertion sequence element or defective prophage in only one strain and two sites for the W3110 inversion. Direct DNA sequencing of PCR products for the 251 regions with short indel and base disparities revealed that only eight sites are true differences. The other 243 discrepancies were due to errors in the original MG1655 sequence, including 79 frameshifts, one amino-acid residue deletion, five amino-acid residue insertions, 73 missense, and 17 silent changes within coding regions. Errors in the original MG1655 sequence (<1 per 13,000 bases) were mostly within portions sequenced with out-dated technology based on radioactive chemistry.

Base Sequence↗

PubMed2006

Early bone in-growth ability of alumina ceramic implants loaded with tissue-engineered bone.

To enhance early bonding of an alumina ceramic implant to bone, we evaluated a method of seeding the implant surface with bone marrow mesenchymal cells that differentiated to osteoblasts and bone matrix prior to implantation. The usefulness of the method was evaluated in Japanese white rabbits. In our study, an alumina ceramic test piece loaded with differentiated osteoblasts and bone matrix by a tissue engineering technique was implanted into rabbit bones. Three weeks after the procedure, evaluation of mechanical bonding and histological examination were performed. Histological examination of the noncell-loaded implant surfaces showed no bone infiltration into the implant gap. However, the cell-loaded implant surfaces exhibited new bone infiltration into the implant gap with mechanical bonding. In the mechanical test, the average failure load was 0.60 kgf for the noncell-loaded side and 1.49 kgf for the cell-loaded side. Preculturing mesenchymal cells on the surface of the alumina ceramic prior to implantation increased the debonding strength by two and half times. The present findings indicate early bonding between the implant and bone three weeks after the procedure.

Alkaline Phosphatase↗

PubMed2006

The functional anatomy of the iliotibial band during flexion and extension of the knee: implications for understanding iliotibial band syndrome.

Iliotibial band (ITB) syndrome is a common overuse injury in runners and cyclists. It is regarded as a friction syndrome where the ITB rubs against (and 'rolls over') the lateral femoral epicondyle. Here, we re-evaluate the clinical anatomy of the region to challenge the view that the ITB moves antero-posteriorly over the epicondyle. Gross anatomical and microscopical studies were conducted on the distal portion of the ITB in 15 cadavers. This was complemented by magnetic resonance (MR) imaging of six asymptomatic volunteers and studies of two athletes with acute ITB syndrome. In all cadavers, the ITB was anchored to the distal femur by fibrous strands, associated with a layer of richly innervated and vascularized fat. In no cadaver, volunteer or patient was a bursa seen. The MR scans showed that the ITB was compressed against the epicondyle at 30 degrees of knee flexion as a consequence of tibial internal rotation, but moved laterally in extension. MR signal changes in the patients with ITB syndrome were present in the region occupied by fat, deep to the ITB. The ITB is prevented from rolling over the epicondyle by its femoral anchorage and because it is a part of the fascia lata. We suggest that it creates the illusion of movement, because of changing tension in its anterior and posterior fibres during knee flexion. Thus, on anatomical grounds, ITB overuse injuries may be more likely to be associated with fat compression beneath the tract, rather than with repetitive friction as the knee flexes and extends.

Adult↗

PubMed2006

Strain differences in the diabetogenic activity of streptozotocin in mice.

We have already reported that slowly progressive non-insulin-dependent diabetes mellitus (NIDDM) is produced by a single i.p. injection of a subdiabetogenic dose (100 mg/kg) of streptozotocin (STZ) to 8-week-old male ICR mice. The aim of the present study was to clarify whether or not the progressive NIDDM is induced in ddY, BALB/c, C57BL/6 and ICR mice by the administration of STZ. Eight-week-old male mice of the 4 different strains were administered a single i.p. injection of STZ at various doses (ICR, ddY and BALB/c: 100-200 mg/kg; C57BL/6: 75-150 mg/kg). Among the ddY, BALB/c and C57BL/6 mice, a time course-related rise in non-fasting serum glucose levels throughout the observation period of 1-12 weeks after STZ administration was only induced in the 125 mg/kg STZ ddY and 100 mg/kg STZ ICR mice. In contrast with serum glucose levels, the area of islets and the percentage of the relative number of insulin-immunoreactive cells (beta-cells) to glucagon-immunoreactive cells (alpha-cells) in the 100 mg/kg STZ ICR and 125 mg/kg STZ ddY mice continued to decrease gradually over time. In addition, in low dose STZ mice of both strains, the insulin response to glucose stimulation was extremely impaired over time, although non-fasting serum insulin levels were maintained near normal levels. The rate of the progression of diabetes was faster in the 125 mg STZ ddY mice than in the 100 mg/kg STZ ICR mice.

Animals↗

PubMed2006

[A steroid-responsive case of severe rhabdomyolysis associated with cytomegalovirus infection].

A 31-year-old man was admitted to our hospital, complaining of muscular weakness and pain in the legs one month after a common cold. On admission, neurological examinations demonstrated moderate weakness in the arms and mild weakness in the legs with decreased or diminished deep tendon reflexes, and mild dysphagia. Weakness was gradually extended to the arm, throat and respiratory muscles, requiring artificial ventilation. Laboratory examinations demonstrated increased levels of CK (upto 24,380 IU/L) and positive anti-cytomegalovirus (CMV) -IgM antibodies in the serum, and myogloburinuria. CMV was not detected in either the blood cells or muscles by PCR. There were no antibodies against viruses including Ebstein-Barr virus and HIV, in the serum. There were no autoantibodies related to collagen diseases in the serum. Systemic PET scan did not show any evidence of malignancy. Bone marrow biopsy did not show any atypical cells. Muscle MRI demonstrated mild atrophy with high intensity signals in part. Muscle biopsy demonstrated scattered necrotic and regenerated muscle fibers without inflammatory cell infiltration. The patient was therefore diagnosed as having rhabdomyolysis associated with CMV infection. After three courses of intravenously administered high dose methylprednislone over three days, muscle weakness improved gradually, and the serum CK level was normalized in two months. The patient recovered and was removed from artificial ventilation three months after the therapy. There were no sign of renal failure. Steroid therapy should be considered for the treatment of rhabdomyolysis or myopathy associated with CMV infection in order to prevent renal failure or fatal progression of the disease.

Adolescent↗

PubMed2005

CCR1 acts downstream of NFAT2 in osteoclastogenesis and enhances cell migration.

UNLABELLED: We found that a chemokine receptor gene, CCR1, acts downstream of NFAT2 in RANKL-stimulated RAW264 and bone marrow cells. The upstream regulatory region of CCR1 showed RANKL-dependent and CsA-suppressible promoter activity. Downregulation of the expression and function of CCR1 suppressed cell migration. INTRODUCTION: We previously reported that the expression of NFAT2 induced by RANKL is a key process for progression to multinucleated cells in an in vitro osteoclastogenesis system. Identifying the target genes of NFAT2 would thus be informative about the differentiation process. We focused here on chemokine and chemokine receptor genes that act downstream of NFAT2 in RAW264 cells as well as osteoclast precursors prepared from bone marrow cells. MATERIALS AND METHODS: RAW264 mouse monocyte/macrophage line cells were cultured with or without cyclosporin A (CsA) in the presence of RANKL or glutathione S-transferase (GST). Osteoclast precursors were prepared from bone marrow cells. RANKL-inducible and CsA-suppressible genes were searched for by microarray analysis, and expression was confirmed by quantitative RT-PCR. Promoter activity was measured by luciferase gene reporter assay. Short interfering (si)RNA for CCR1 was introduced in RAW264 cells. Cell migration activity was examined using a Boyden chamber assay. RESULTS AND CONCLUSIONS: We identified the chemokine receptor gene CCR1 as a gene showing significant differential expression profiles in osteoclastogenesis in the presence versus the absence of CsA, an inhibitor of NFAT. This property was unique to CCR1 among the chemokine and chemokine receptor genes examined in both RAW264 and bone marrow cells. The upstream regulatory region was isolated from CCR1, and its RANKL-dependent and CsA-suppressible promoter activity was confirmed. The functional significance of CCR1 was assessed by monitoring the migration of cells in a transwell migration assay, and this activity was abolished when either CsA- or CCR1 siRNA-treated cells were used. Moreover, treatment with a Galpha inhibitor pertussis toxin (PTX) or methiolynated-regulated on activation, normal T cells expressed and secreted (Met-RANTES), an antagonist of CCR1, suppressed multinucleated cell formation in the bone marrow cell system. Together, these results suggest that the CCR1 signaling cascade is under the control of NFAT2 and seems to enhance the migration of differentiating osteoclasts.

Animals↗

PubMed2005

Signal sequence and keyword trap in silico for selection of full-length human cDNAs encoding secretion or membrane proteins from oligo-capped cDNA libraries.

We have developed an in silico method of selection of human full-length cDNAs encoding secretion or membrane proteins from oligo-capped cDNA libraries. Fullness rates were increased to about 80% by combination of the oligo-capping method and ATGpr, software for prediction of translation start point and the coding potential. Then, using 5'-end single-pass sequences, cDNAs having the signal sequence were selected by PSORT ('signal sequence trap'). We also applied 'secretion or membrane protein-related keyword trap' based on the result of BLAST search against the SWISS-PROT database for the cDNAs which could not be selected by PSORT. Using the above procedures, 789 cDNAs were primarily selected and subjected to full-length sequencing, and 334 of these cDNAs were finally selected as novel. Most of the cDNAs (295 cDNAs: 88.3%) were predicted to encode secretion or membrane proteins. In particular, 165(80.5%) of the 205 cDNAs selected by PSORT were predicted to have signal sequences, while 70 (54.2%) of the 129 cDNAs selected by 'keyword trap' preserved the secretion or membrane protein-related keywords. Many important cDNAs were obtained, including transporters, receptors, and ligands, involved in significant cellular functions. Thus, an efficient method of selecting secretion or membrane protein-encoding cDNAs was developed by combining the above four procedures.

5' Flanking Region↗

PubMed2005

Modeling of driver's collision avoidance maneuver based on controller switching model.

This paper presents a modeling strategy of human driving behavior based on the controller switching model focusing on the driver's collision avoidance maneuver. The driving data are collected by using the three-dimensional (3-D) driving simulator based on the CAVE Automatic Virtual Environment (CAVE), which provides stereoscopic immersive virtual environment. In our modeling, the control scenario of the human driver, that is, the mapping from the driver's sensory information to the operation of the driver such as acceleration, braking, and steering, is expressed by Piecewise Polynomial (PWP) model. Since the PWP model includes both continuous behaviors given by polynomials and discrete logical conditions, it can be regarded as a class of Hybrid Dynamical System (HDS). The identification problem for the PWP model is formulated as the Mixed Integer Linear Programming (MILP) by transforming the switching conditions into binary variables. From the obtained results, it is found that the driver appropriately switches the "control law" according to the sensory information. In addition, the driving characteristics of the beginner driver and the expert driver are compared and discussed. These results enable us to capture not only the physical meaning of the driving skill but the decision-making aspect (switching conditions) in the driver's collision avoidance maneuver as well.

Accidents, Traffic↗

PubMed2004

Gastric dysmotility associated with accumulation of mitochondrial A3243G mutation in the stomach.

OBJECTIVE: We analyzed the accumulation of a mitochondrial A-to-G mutation at nucleotide position 3243 (A3243G) in the stomach and gastric motility in patients with gastric symptoms, post-prandial nausea/vomiting and epigastralgia. METHODS: Detection and quantification of A3243G mutation in mtDNA in the gastric mucosa, oral mucosa, leukocyte, and skeletal muscle were performed. Gastric motility was evaluated by gastric myoelectrical activity on electrogastrography (EGG), and gastric emptying was evaluated by measurement of plasma paracetamol concentration before and after meals. PATIENTS OR MATERIALS: Four patients with A3243G mutation in the leukocyte mtDNA and gastric symptoms were examined. RESULTS: The A3243G mutation was detected at higher percentages in the gastric body (69-94% for mutation; mean, 83%) than in the angle portion (37-82%; mean, 52%), the antrum (40-84%; mean, 57%) or leukocytes (28-52%; mean, 39%), and at slightly higher percentages than in the skeletal muscles (45-87%; mean, 70%) or oral mucosae (52-86%; mean, 69%) in the four patients examined. Abnormal EGGs were observed in the three patients examined. The pre-prandial myoelectrical activities were low in these patients (49% in patient 1, 54% in patient 2, 63% in patient 3; normal >70%). The plasma concentrations of paracetamol were low (3.6 microg/ml in patient 1, 2.4 microg/ml in patient 2, <2.0 microg/ml in patient 3; normal, 7-12 microg/ml). CONCLUSION: Accumulation of mitochondrial A3243G mutation in the stomach is a contributory factor in gastric dysmotility and gastric symptoms in patients with the mutation in their leukocytes.

Adult↗

PubMed2004

[Surgical treatment for pulmonary mycosis].

Although most human mycosis develops in immunocompromised patients as an opportunistic infection, its frequency will be influenced by historical changes in diseases and by progress in medical technology. An example of local occurrence is pulmonary aspergilloma in an open negative cavity, and a systemic example is the onset of invasive pulmonary aspergillosis in neutropenic patients with hematologic malignancies. Surgical candidates for mycotic lung disease are usually patients who do not improve with medical treatment The author also stresses the prophylactic indications for prevention of unexpected impairment due to mycotic lung disease. The usefulness of surgery for pulmonary fungal infection has gradually been recognized Additional efforts should be made by surgeons to achieve better outcomes and to minimize operative complications by choosing the appropriate surgical technique.

Aspergillosis↗

PubMed2003

Complete sequencing and characterization of 21,243 full-length human cDNAs.

As a base for human transcriptome and functional genomics, we created the "full-length long Japan" (FLJ) collection of sequenced human cDNAs. We determined the entire sequence of 21,243 selected clones and found that 14,490 cDNAs (10,897 clusters) were unique to the FLJ collection. About half of them (5,416) seemed to be protein-coding. Of those, 1,999 clusters had not been predicted by computational methods. The distribution of GC content of nonpredicted cDNAs had a peak at approximately 58% compared with a peak at approximately 42%for predicted cDNAs. Thus, there seems to be a slight bias against GC-rich transcripts in current gene prediction procedures. The rest of the cDNAs unique to the FLJ collection (5,481) contained no obvious open reading frames (ORFs) and thus are candidate noncoding RNAs. About one-fourth of them (1,378) showed a clear pattern of splicing. The distribution of GC content of noncoding cDNAs was narrow and had a peak at approximately 42%, relatively low compared with that of protein-coding cDNAs.

Chromosomes, Human, 21-22 and Y↗

PubMed2003

[Adult cases of viral meningitis caused by echovirus type 13].

Adult cases of viral meningitis caused by echovirus type 13 (E13) were studied. E13 was isolated from 8 of 11 adult patients (73%) with viral meningitis between April and September 2002 in Fukui Prefecture. The mean age was 27.4 +/- 6.4 years (4 males and 4 females). The disease was prevalent among adults, especially younger adults as well as children. The symptoms and signs were as follows; headache (100%), fever (100%), nausea and/or vomiting (88%), Kernig's sign (88%), and increased deep tendon reflexes (50%). The average cell counts in cerebrospinal fluid (CSF) were 118 +/- 111/mm3. Of the 2 patients, polynuclear cells were dominant during the early phase of the disease. The prognosis was good. Since May 2002, the number of patients with viral meningitis caused by E13 has rapidly increased. Most of the reported patients were children. We should consider the possibility of E13 infection as a cause of adult viral meningitis.

Adolescent↗

PubMed2002

Large scale gene expression analysis of osteoclastogenesis in vitro and elucidation of NFAT2 as a key regulator.

To understand the molecular events coupling between cell proliferation and differentiation by elucidating genes essential for the process, we conducted a large scale gene expression analysis of an in vitro osteoclastogenesis system consisting of recombinant RANKL and mouse RAW264 cells. The entire process leading to the formation of tartrate resistant acid phosphatase-positive multinucleated cells takes 3 days and plates become fully covered with multinucleated cells at 4 days. Microarray probing at eight time points revealed 635 genes that showed greater than 2-fold differential expression for at least one time point and they could be classified into six groups by the "k-means" clustering analysis. Among a group of 106 early inducible genes (within 2-5 h after RANKL stimulation), four genes including NFAT2 were identified as genes whose enhanced expressions were fairly correlated with an efficient induction of matured osteoclasts. Moreover, cyclosporin A significantly suppressed the multinucleated cell formation accompanying the reduction of the nuclear localization of NFAT2. When the expression of NFAT2 was suppressed by introducing antisense NFAT2, multinucleated cell formation was severely hampered. Functional analysis thus combined with gene analysis by microarray technology elucidated a key role of NFAT2 in osteoclastogenesis in vitro.

Animals↗

PubMed2002

Antidiabetic action of low molecular weight chitosan in genetically obese diabetic KK-Ay mice.

Recently, we reported that low molecular weight (LMW) chitosan (chitosan lactate, average MW: 20,000) prevents the progression of low dose (100 mg/kg, i.p.) streptozotocin-induced slowly progressive diabetes mellitus in male ICR mice. The present study was designed to clarify the effects of LMW chitosan on hyperglycemia, hyperinsulinemia and hypertriglyceridemia in genetically obese diabetic male KK-Ay mice. LMW chitosan (0.05%, 0.2% or 0.8% water solution) was given daily as drinking water to male KK-Ay mice for 11 weeks, from 5 weeks of age. The non-fasting serum glucose levels of control mice continued to increase slowly throughout the experimental period. LMW chitosan lowered the serum glucose levels in a dose-dependent manner. In these diabetic mice, hyperinsulinemia and hypertriglyceridemia were observed, and LMW chitosan was dose-dependently effective in improving both serum biochemical parameters. LMW chitosan at three doses improved overdrinking and polyuria observed in these diabetic mice. It is concluded from these results that LMW chitosan may be useful for the treatment of obesity-related type 2 diabetes mellitus.

Animals↗

PubMed2002

Involvement of caspase 3 mediated apoptosis in hematopoietic cytotoxicity of metabolites of ethylene glycol monomethyl ether.

The hematopoietic toxicity of ethylene glycol monomethyl ether (EGME) and its metabolites, methoxy acetaldehyde (MALD) and methoxyacetic acid (MAA), was analyzed using human bone marrow cells from a lymphoma patient without bone marrow involvement and a human leukemia cell line, HL60. After 24-hour incubation, the concentrations of 50 percent inhibition (IC50) of human hematopoietic progenitor cells with MALD or MAA were 3 mM and 3.9 mM, respectively, and EGME (10 mM or more) did not show any cytotoxicity. IC50 (after 48-hour exposure) of MALD and MAA on HL60 cells were 2.45 mM and 5.6 mM, respectively, suggesting that both hematopoietic progenitor cells and HL60 have a similar sensitivity. DNA ladder formation, a characteristics of apoptosis, was observed in MALD- or MAA-treated HL60 cells, but not in EGME-treated samples. Caspase-3 enzyme activity, the effector of the apoptotic process, was greatly enhanced with MALD treatment. The inhibitor of caspase-3 repressed cell death induced with MALD as well as MAA.

Acetaldehyde↗

PubMedDate not supplied

Susceptibility-induced changes in signal intensity from spin-echo versus gradient-echo sequences.

This manuscript describes a study of the evaluation of T2 and T2* changes in a hypervascular tumor model (hemodialyzer phantom) under conditions simulating dynamic perfusion study. The measured 1/T2* was strongly dependent on the compartmentalization of contrast material within the model, whereas the observed 1/T2 was not. Gradient-echo magnetic resonance (MR) imaging may be more suitable than a spin-echo MR imaging for the evaluation of tumor vascularity.

Contrast Media↗