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Biomedical subjects

Kenji Yokoyama

Publications and source records attributed to Kenji Yokoyama.

35 records · Page 2Linked to original sources
PubMed2003

Spontaneous hematoma of the lateral abdominal wall caused by a rupture of a deep circumflex iliac artery: report of two cases.

Expanding hematoma of the abdominal wall is a rare example of acute abdominal disease. We report two cases of lateral abdominal wall hematoma caused by the rupture of a deep circumflex iliac artery, which is a rare cause of an abdominal wall hematoma. Both patients experienced severe abdominal pain after sneezing or coughing. In both cases, computed tomography (CT) findings suggested that active bleeding was continuing. Emergent angiography was therefore performed, and the hematoma was embolized using Spongel or Microcoils. Ultrasound examinations were repeatedly used to monitor the size of the hematoma. The size of the hematoma and patient's pain gradually decreased after embolization. Ultrasound and CT examinations provided useful information for the differential diagnosis of this disease. We conclude that emergent angiography should be performed to control bleeding and avoid any unnecessary surgical procedures in patients with hematoma of the abdominal wall.

Abdominal Wall↗
PubMed2003

CT diagnosis of small bowel obstruction: scanning technique, interpretation and role in the diagnosis.

Intestinal obstruction is a relatively common condition with diagnosis based on the clinical signs, patient history, and radiographical findings. Once suspected, its presence should be determined and if present, the site and cause of obstruction, and presence of strangulation should be assessed for the appropriate patient management. With the recent technological developments, the role of computed tomography (CT) in the diagnosis of bowel obstruction has expanded. The examination should be performed with intravenous contrast administration and thinner sections and multi-planner image reformation are recommended to evaluate a site of particular interest. CT is reported to have a sensitivity refer to detection of a small bowel obstruction at over 90% for complete or high-grade obstruction and to disclose causes of obstruction in 70% to 95% of cases. CT also provides characteristic findings indicating the presence of closed-loop obstruction and intestinal ischemia, which leads to appropriate and timely management for these emergent cases.

Diagnosis, Differential↗
PubMed2003

Internal mammary artery steal in a dialysis patient.

A 67-year-old man with chronic renal failure who was being treated with dialysis through an arteriovenous fistula in the left arm was scheduled to undergo off-pump coronary artery bypass grafting. Angiography detected the steal phenomenon in the left internal mammary artery during the diastolic phase. Postoperative study with Doppler guidewire showed that the steal of the left internal mammary artery was due to an ipsilateral arteriovenous fistula. Preoperative angiography of the internal mammary artery is therefore recommended for patients on dialysis.

Aged↗
PubMed2003

Pregnancy-related increases in sensory perception thresholds are not correlated with serum progesterone levels.

BACKGROUND: Why pregnant women require smaller doses of anesthetic agents still remains speculative. One hypothesis proposes that pregnancy raises sensory perception thresholds, perhaps through a progesterone-mediated effect. This study was undertaken in order to quantify any changes in sensory perception thresholds after parturition and to correlate these changes with the expected decrease in postpartum serum progesterone levels. METHODS: Nineteen gravid women scheduled to undergo an elective Cesarean section consented to participate. Sensory current perception threshold (CPT) testing was performed before and 7 days after an elective Cesarean section. CPT was defined as the minimum amount of constant current stimulation that can be reproducibly detected at a particular frequency. CPT values were determined on the distal phalanx of the nondominant index finger at 2000 Hz, 250 Hz, and 5 Hz monofrequency stimulation. Seven women permitted serum progesterone level determinations at the prepartum and the postpartum CPT testing sessions. RESULTS: Parturition resulted in a statistically significant decrease in the sensory CPT at all 3 frequencies tested, (p < 0.05). However, there was no significant correlation between the postpartum reduction in serum progesterone levels and the observed postpartum decrease in CPT for any frequency, (r < 0.5). CONCLUSIONS: CPTs are significantly reduced after parturition. However, this reduction does not appear to be significantly correlated with the reduction in serum progesterone levels.

Journal Article↗
PubMed2003

Self-assembled DNA-conjugated polymer for novel DNA chip.

We developed DNA-conjugated polymer for DNA chip fabrication. A 30 mer probe DNA and disulfide bridges were covalently attached to the polymer side chain. The DNA-conjugated polymer can be specifically adsorbed on a gold substrate surface by a self-assembly technique. The interaction between fully matched DNA and DNA-conjugated polymer was investigated by surface plasmon resonance (SPR) technique. The DNA-conjugated polymer-modified gold surface highly recognized fully matched DNA, rather than unmatched DNA. Therefore, DNA-conjugated polymer can be used for novel DNA chip fabrication.

Base Sequence↗
PubMed2003

Design of peptide that recognizes double-stranded DNA.

A novel molecular tool for double-stranded (ds) DNA detection using synthetic peptide is described. The peptide was designed based on the DNA binding domain of the lambda phage CRO repressor (CRO). The designed peptides contain helix-turn-helix (HTH), which is DNA binding motif. A cyclic peptide and a mutant peptide based on CRO were also designed, and the resulting affinity for dsDNA was increased. Furthermore, native amino acids of the peptide were replaced with arginine to increase the affinity for dsDNA. The affinity of these peptides for DNA binding was assessed by surface plasmon resonance (SPR) technique.

Amino Acid Sequence↗
PubMed2003

Evaluation of the molecular recognition of peptide-conjugated polymer.

We have recently reported on dodecamer peptides (HPPMDFHKAMTR, CHPQPLKSRNPL) which recognize 52-58th and 197-203rd amino acid sequences of glucose oxidase (GOx) by screening via a phage random peptide library. In this study, a side-chain protected peptide monomer (PPM) was synthesized using two peptides (HPPMDFHKAMTR, SHPQPLKSRNPL) and acryloyl chloride. The peptide-conjugated polymer (PCP) was copolymerized with PPMs and N,N-diethylacrylamide (DEAA). The affinity of PCPs to GOx was estimated using surface plasmon resonance detection. This study suggests that PCP is a valuable molecular recognition biomolecule.

Amino Acid Sequence↗
PubMed2003

[The diagnosis of ITP].

Idiopathic thrombocytopenic purpura(ITP) is a hematologic disorder which causes thrombocytopenia. The diagnosis of ITP is based on the history, physical examination and, complete blood count, and examination of the peripheral smear. The diagnostic criteria of ITP established by the Ministry of Health, Welfare, and Labor in Japan requires the bone marrow examination and the measurement of platelet associated IgG, but those tests are not always necessary according to the guidelines developed by the American Society of Hematology. The appropriate strategies for the diagnosis of ITP need to be established. In this paper, some new examinations which may help the diagnosis of ITP are also demonstrated.

Humans↗
PubMed2003

[Chronic myelogenous leukemia in a lymphoblastic crisis complicated with deep venous thrombosis successfully treated by thromboembolectomy].

A 20-year-old man was referred to our hospital because of leukocytosis and was diagnosed as having chronic myelogenous leukemia in lymphoblastic crisis. His left leg began to swell soon after the beginning of induction chemotherapy and deep vein thrombosis (DVT) was confirmed by doppler echography, which progressed to compartment syndrome next day. After placing a venous filter in the inferior vena cava, the patient successfully underwent thromboembolectomy. Venous congestion due to massive lymphadenopathy enlarged kidneys, and a hypercoagulable condition due to the rapid destruction of leukemic cells may have contributed to the formation of the thrombus. This case demonstrates the importance of aggressive surgical intervention for severe DVT in patients with leukemia.

Adult↗
PubMed2002

Keratin degradation: a cooperative action of two enzymes from Stenotrophomonas sp.

A novel keratin-degrading bacterium Stenotrophomonas sp. strain D-1, isolated from deer fur, produced two types of extracellular proteins: proteolytic and disulfide bond-reducing. The results on the biochemical properties suggest that this protease belongs to the serine protease, and the disulfide bond-reducing protein could be the disulfide reductase type. None of these enzymes showed keratinolytic activity independently. However, after mixing of the two enzymes, the keratinolytic activity was increased tremendously (more than 50-fold) over that of the protease only. This keratinolytic activity was more than 2-fold higher than that of the combination with proteinase K (also known for its high keratinolytic activity). Since the two enzymes discovered in this study acted cooperatively and resulted in higher keratinolytic activity, a new mechanism of keratin degradation has been revealed. To our knowledge, this is the first report on the cooperative action of two enzymes resulting in the effective degradation of keratin.

Bacterial Proteins↗
PubMed2002

Long-term follow-up of allogeneic bone marrow transplantation after reduced-intensity conditioning in patients with chronic myelogenous leukemia in the chronic phase.

Although allogeneic transplantation is a curative therapy for chronic myelogenous leukemia (CML), treatment-related mortality is still a major cause of death after transplantation, especially in older patients. We investigated the safety and efficacy of reduced-intensity conditioning consisting of low-dose (600 cGy) total body irradiation and cytosine arabinoside (1 g/m2) together with a continuous infusion of granulocyte colony-stimulating factor and cyclophosphamide (120 mg/kg) in patients with CML in the chronic phase. Fractionated splenic irradiation (5 Gy) was also administered as part of the conditioning treatment. Eight patients older than 40 years underwent allogeneic bone marrow transplantation from an HLA-matched sibling following this conditioning. Regimen-related toxicities (equal to or greater than grade III) were not observed. Rapid restoration of 100% donor chimerism was confirmed by fluorescence in situ hybridization methods in 5 sex-mismatched transplant recipients. One patient died from severe acute graft-versus-host disease and another from Pneumocystis carinii pneumonia early in the course of transplantation. A sustained engraftment was achieved in 5 long-term survivors; in 1 case, the graft was rejected but the Philadelphia chromosome and BCR/ABL-negative autologous hemopoiesis were restored. After a minimum follow-up period of 60 months, 6 patients, including the patient with restored autologous hemopoiesis, were still alive and in remission with 100% donor chimerism. Six years after the transplantation, 1 patient experienced a cytogenetic relapse, which was successfully treated with donor lymphocyte infusions. In summary, this reduced-intensity conditioning resulted in a cure with markedly reduced regimen-related toxicities in this relatively older cohort of patients with CML.

Adult↗
PubMed2002

A novel polymorphism, 70Leu/Phe, disrupts a consensus Leu residue within the leucine-rich repeat sequence of platelet glycoprotein Ibalpha.

Platelet glycoprotein (GP) Ib/IX/V complex mediates high-shear dependent platelet activation through an interaction with the von Willebrand factor (vWF). All four subunits of the complex have a structural motif, the leucine-rich repeat (LRR) sequence, with leucines in conserved positions. Here we report a new polymorphism, Leu/Phe at residue 70 of GPIbalpha, which disrupts the consensus sequence of the LRR in the vWF binding domain. Genotype frequencies among 142 healthy Japanese subjects were 92.3%, 7.7%, and 0.0%, for the 70Leu/Leu, 70Leu/Phe, and 75Phe/Phe genotypes, respectively. Ristocetin-induced or shear-induced platelet aggregation was not significantly different between the 70Leu/Leu and 70Leu/Phe genotypes. In in vitro studies, a recombinant GPIbalpha fragment with 70Phe (L70F) as compared to that with 70Leu (WT) had low reactivity to anti-GPIbalpha monoclonal antibodies, GUR20-5 and Hip1, both of which recognize conformation-specific epitopes within the 45-kDa domain. Ristocetin-induced 125I-vWF binding to L70F, however, did not differ from that to WT.

Amino Acid Substitution↗
PubMed2002

Characterization of a new keratin-degrading bacterium isolated from deer fur.

A keratin-degrading bacterium was isolated from soil containing deer fur. An axenic culture of the keratin-degrading bacterium was obtained in liquid culture using a keratin enrichment technique. The isolated bacterium was gram negative and catalase- and oxidase-positive. Transmission electron microscopic observations showed that the bacterium was rod-shaped, 1.0-1.3 microm long and 0.7 microm in diameter. Phylogenetic analysis of 16S rDNA revealed that the new isolate has only 90.6% homology with Stenotrophomonas nitritireducens. Hence, this new bacterium was designated as Stenotrophomonas sp. D-1. The optimum temperature was determined to be 20 degrees C for maximum growth and keratinolytic enzyme production. Amino acid data, obtained after treating keratin powder with the supernatant culture, suggest that the major free amino acids resulting from keratin degradation are phenylalanine, tyrosine and valine. In addition, native chicken feather was degraded completely at 20 degrees C in 2.5 d by this bacterium.

Journal Article↗
PubMed2001

Cyclic voltammetric simulation of electrochemically mediated enzyme reaction and elucidation of biosensor behaviors.

A cyclic voltammetric simulation that can be applied to an electrochemically mediated enzyme reaction involving any substrate and mediator concentration was developed. Concentration polarization of the substrate in the vicinity of an electrode was considered as well as mediator concentration. Reversible electrochemical reaction with one electron followed by an enzyme reaction with two electrons was modeled. The differential equations for the mediator and substrate were solved using digital simulation techniques. The calculated cyclic voltammograms showed prepeaks when there was a low substrate concentration, high mediator concentration, and high enzyme activity. The prepeak was experimentally observed in the case of an enzyme electrode co-immobilized with a redox polymer. The enzyme electrode loaded at high redox polymer and high enzyme content showed a prepeak at low substrate concentration in the cyclic voltammogram.

Biosensing Techniques↗