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Biomedical subjects

K Yamada

Publications and source records attributed to K Yamada.

At least 73 records · Page 4Linked to original sources
PubMed2004

Determination of vitamin B12 using the enzyme glycerol dehydrase.

Glycerol dehydrase is an enzyme that catalyzes dehydration of glycerol into beta-propionaldehyde. It requires 5'-deoxyadenosylcobalamin, one of the forms of vitamin B12, as a coenzyme. The enzyme is inactivated in vitro by all forms of vitamin B12 stoichiometrically. The objective of this study was to determine vitamin B12 content by utilizing the inactivation of the enzyme by vitamin B12. After various examinations, an excellent standard curve was obtained up to 1 pmol vitamin B12 using 14 mU of the enzyme per tube. Glycerol dehydrase does not respond to vitamin B12 if it is bound to haptocorrin, a vitamin B12-binding protein. This necessitates a procedure for extraction of vitamin B12 from samples before assay. The enzyme was less inactivated by 5'-deoxyadenosylcobalamin than any other form of vitamin B12. However, this did not matter because all forms of vitamin B12 were converted into cyanocobalamin during the extraction procedure cited above, which was performed in a buffer containing potassium cyanide.

Aldehydes↗
PubMed2004

Perioperative evaluation of carotid endarterectomy by 3D-CT angiography with refined reconstruction: preliminary experience of CEA without conventional angiography.

Three-dimensional CT angiography (3D-CTA) was employed for perioperative evaluation of carotid endarterectomy (CEA) as an alternative to conventional angiography. A total of 62 carotid arteries were examined before and after CEA, 26 with an early 3D-CT system and 36 with multidetector helical CT allowing sophisticated reconstruction by a personal workstation. In addition to patients who had undergone conventional angiography at other institutes, 10 subjects underwent CEA on the basis of 3D-CTA findings alone. The findings provided detailed information with an excellent view of carotid stenoses. Volume rendering images comprehensively visualized lesions and surrounding structures as well as calcifications, which were also well depicted by maximum intensity projection images. Evaluation of the cerebral circulation is one problem that still requires solution, although cerebral vessels were delineated by 3D-CTA. One patient experienced transient hemiparesis, but no significant permanent deficit. We conclude that 3D-CTA is a safe and accurate modality that is a practical alternative to conventional perioperative angiography.

Aged↗
PubMed2004

CT-based evaluation of axillary sentinel lymph node status in breast cancer: value of added contrast-enhanced study.

PURPOSE: To evaluate the diagnostic reliability of CT-based sentinel lymph node (SLN) size criteria for selecting the candidates for direct axillary dissection without SLN biopsy and to determine the value of added contrast-enhanced study. MATERIAL AND METHODS: Breast cancer patients (n = 107) underwent triple phasic (1-min, 3-min, 8-min) contrast-enhanced 5 mm-computed tomography (CT) of the breasts and axillae. In the CT image, the most inferior lymph node in the axilla was designated the SLN. Axillary status was judged based on SLN size criteria. CT density, enhancement rate, and peak enhancement time of each SLN were correlated with histopathological results. RESULTS: SLN size criteria demonstrated a sensitivity of 76% and a positive predictive value of 95% in predicting SLN metastasis. The density values at each scanning time-point were significantly different for metastatic and non-metastatic SLN. However, their enhancement rates differed significantly only at 1 min. Their peak enhancement occurred primarily at 1 min. The use of contrast-enhancement criteria improved the predictive sensitivity, but failed to decrease the false-positive rate of the SLN size criteria. CONCLUSION: The enhancement rate at 1 min proved to be the most useful parameter in contrast-enhanced CT studies; however, it failed in improving the accuracy of the SLN size criteria.

Adult↗
PubMed2004

Mutations in the hypoxanthine guanine phosphoribosyltransferase gene (HPRT1) in Asian HPRT deficient families.

Inherited mutation of hypoxanthine guanine phosphoribosyltransferase, (HPRT) gives rise to Lesch-Nyhan syndrome or HPRT-related gout. We have identified 34 mutations in 28 Japanese, 7 Korean, and 1 Indian families with the patients manifesting different clinical phenotypes, including two rare cases in female subjects, by the analysis of all nine exons of HPRT from the genomic DNA and reverse transcribed mRNA using PCR technique coupled with direct sequencing.

Exons↗
PubMed2004

Genetic polymorphisms and antiviral activity in the bovine MX1 gene.

Bovine MX1 cDNAs consisting of 2280 bp from 11 animals of five breeds and from a cultured cell line were sequenced and compared with previously reported data. Ten nucleotide substitutions were synonymous mutations, and a single nucleotide substitution at 458 resulted in an amino acid exchange of Ile (ATT) and Met (ATG). A 13-bp deletion-insertion mutation was also found in the 3'-UTR. Based on the nucleotide substitutions found in this study, bovine MX1 cDNA was classified into 11 genotypes. A phylogenetic tree of the 11 genotypes suggested that the genotypes observed in Brahman were a great genetic distance from other genotypes. An 18-bp deletion-insertion variation at position 171 was found to be the result of alternative splicing. The 18-bp deletion-insertion is located at the boundary between exon 3 and intron 3. Permanently transfected 3T3 cell lines expressing bovine MX1 mRNA were established to analyse the antiviral potential against VSVDeltaG*-G infection. Transfected cell clones expressing bovine MX1 mRNA showed a significantly smaller number of cells infected with VSVDeltaG*-G compared with the control cells. These results indicate that the bovine MX1 protein has potent antiviral activity.

3T3 Cells↗
PubMed2004

Morphology of the articular eminence in temporomandibular joints and condylar bone change.

The purpose of the present study was to investigate the relationship between the inclination of the articular eminence and temporomandibular joint (TMJ) pathology in orthognathic surgery patients with signs and symptoms of TMJ disorders. Twenty-one female orthognathic surgery patients with signs and symptoms of TMJ disorders were examined using pre-treatment helical computed tomography scans. The slope of the eminence in the medial, central and lateral sections of the subjects with osteophyte formation was significantly less than in the subjects with no bone change, and the medial section of the subjects with osteophyte formation was also significantly less steep than in the subjects with erosion. The central and lateral sections in the subjects with anterior disc displacement with reduction were significantly steeper than in subjects with anterior disc displacement without reduction. These results suggest that eminence flattening might occur during changes from erosion to osteophyte formation and from anterior disc displacement with reduction to anterior disc displacement without reduction. This appears to represent adaptation of the condyle, articular disc and articular eminence to changes in loading.

Adolescent↗
PubMed2004

Comparison of condylar positions at intercuspal and reference positions in patients with condylar bone change.

The purpose of this study was to investigate the condylar displacement from intercuspal position (IP) to reference position (RP), using a jaw movement measuring system with 6 d.f. and helical computed tomography (CT). The 19 patients included in the present study were divided into a group with bilateral condylar bone change (10 subjects, including the sub-groups with flattening and osteophyte formation) and a group with no condylar bone change (9 subjects). The results showed that the bone change group had significantly more superior, posterior and absolute horizontal IP to RP slides than the no bone change group. There was also a significant difference in the amount of antero-posterior and supero-inferior condylar IP-RP displacements related to the type of condylar bone change within the bone change group. The osteophyte sub-group showed the largest posterior displacement, and the flattening sub-group showed the largest superior displacement. These results suggested that this large IP-RP difference in the bone change group might be related to their temporomandibular joint (TMJ) pathology, and it might therefore be useful to keep this difference in mind as one of the clinical indices suggesting the presence of TMJ osteoarthritis (OA).

Adult↗
PubMed2004

The effect of Goldbonder on the adhesion between porcelain and pure titanium.

The present study examines the effect of a Goldbonder on the adhesion between titanium and porcelain as measured by the strain energy release rate (G) associated with the interfacial fracture of porcelain and titanium. The influence of surface treatment of titanium prior to Goldbonder application was also examined. The porcelain side of the specimens was notched to the interface with a thin diamond saw, and then a pre-crack was made at the metal-porcelain interface by a special jig. The samples were subjected to a four-point bending test resulting in stable crack extension from which G was calculated. Both the cracked cross-section of interface and peeled fracture surface were examined with scanning electron microscope (SEM). The mean G values were 81.57 +/- 10.34, 46.01 +/- 14.83, and 15.98 +/- 1.76 J m(-2) for the sandblasted surface with the Goldbonder, polished surface with the Goldbonder, and sandblasted surface with the Pastebonder, respectively. The G values revealed significant differences (P < 0.01) between Goldbonder and Pastebonder, and between the sandblasted and polished surfaces with Goldbonder. The SEM photographs and elemental analysis showed that Goldbonder developed both chemical and mechanical bonding to titanium and porcelain.

Dental Bonding↗
PubMed2004

Facile synthesis of Nalpha-protected-L-alpha,gamma-diaminobutyric acids mediated by polymer-supported hypervalent iodine reagent in water.

Hofmann rearrangement of Nalpha-Boc-L-Gln-OH mediated by a polymer-supported hypervalent iodine reagent poly[(4-diacetoxyiodo)styrene] (PSDIB) in water afforded Nalpha-Boc-L-alpha,gamma-diaminobutyric acid (Boc-Dab-OH, 1) in 87% yield. Nalpha-Z-derivative (Z-Dab-OH, 2) was prepared with PSDIB in 83% yield. Since the reaction of Nalpha-Fmoc-Gln-OH by this procedure did not proceed because of the insolubility of Fmoc-Gln-OH in aqueous media, we synthesized Fmoc-Dab(Boc)-OH (5) from 2 in 54% yield. Polymyxin B heptapeptide (PMBH) which contains four Dab residues was successfully synthesized in a solution-phase synthesis.

Amino Acids↗
PubMed2004

Bone marrow transplantation from alpha1,3-galactosyltransferase gene-knockout pigs in baboons.

BACKGROUND: Successful hematopoietic cell allotransplantation results in donor-specific tolerance, but this approach has been unsuccessful in the wild-type pig-to-baboon xenotransplantation model, as pig cells were lost from the circulation within 5 days. However, after cessation of immunosuppressive therapy on day 28, all baboons demonstrated non-specific unresponsiveness on mixed leukocyte reaction (MLR) for at least 30 days. We have now investigated the transplantation of bone marrow (BM) cells from miniature swine homozygous for alpha1,3-galactosyltransferase gene-knockout (GalT-KO). METHODS: Baboons (n = 3) were pre-treated with whole body and thymic irradiation, anti-thymocyte globulin, and splenectomy, and received immunosuppressive and supportive therapy for 28 days. BM was harvested from GalT-KO swine (n = 3). The baboons were monitored for the presence of pig cells by flow cytometry and colony-forming units (CFUs), and for cellular reactivity by MLR. RESULTS: A mean of 11 x 10(8) BM cells/kg was infused into each baboon. The mean absolute numbers and percentages of pig cells detected in the blood at 2 h and on days 1, 2 and 4, respectively, were 641/microl (9.5%), 132/microl (3.4%), 242/microl (3.9%), and 156/microl (2.9%). One baboon died (from accidental hemorrhage) on day 6, at which time chimerism was present in the blood (2.0%) and BM (6.4%); pig cell engraftment in the BM was confirmed by polymerase chain reaction (PCR) of CFUs. In the two other baboons, blood chimerism was lost after day 5 but returned at low levels (<1%) between days 9 to 16 and 7 to 17, respectively, indicating transient BM engraftment. Both surviving baboons showed non-specific unresponsiveness on MLR until they were euthanized on days 85 and 110, respectively. CONCLUSIONS: By using BM cells from GalT-KO pigs, chimerism was detected at levels comparable with previous studies when 30-fold more growth factor-mobilized peripheral blood progenitor cells had been transplanted. In addition, cellular hyporesponsiveness was prolonged. However, long-term engraftment and chimerism were not achieved.

Animals↗
PubMed2004

Impact of adiposity and plasma adipocytokines on diabetic angiopathies in Japanese Type 2 diabetic subjects.

AIMS: Adipocytokines, products from adipose tissue, have biological activities on the vascular system, and may affect diabetic angiopathy. In this study, we assessed the relationship between adiposity and plasma adipocytokine levels, and investigated the clinical significance of adiposity and plasma adipocytokine levels on diabetic micro- and macroangiopathy in Type 2 diabetic subjects. METHODS: We studied 231 Japanese Type 2 diabetic subjects (135 men and 96 women, aged 60.4 +/- 12.3 years, body mass index 24.8 +/- 5.2 kg/m2). We measured adipocytokine [adiponectin, leptin, resistin, and tumour necrosis factor (TNF)-alpha] levels, lipid profiles and urine albumin excretion. We also performed optic fundus examination and measured carotid intramedia thickness (IMT) using B-mode ultrasonography, and the localization of fat with abdominal computed tomography. A group of 93 subjects with microalbuminuria or overt proteinuria was compared with the other 148 to assess the effect on nephropathy. A group of 191 eyes with simple retinopathy or more advanced changes was compared with 263 eyes without retinal changes to assess the effect on retinopathy. RESULTS: Plasma adiponectin level was negatively correlated with both visceral (r = -0.37, P < 0.01) and subcutaneous (r = -0.25, P < 0.01) fat areas. Resistin concentration was positively related with visceral fat area (r = 0.15, P < 0.05). Adiponectin concentration was positively correlated with age (r = 0.26, P < 0.01). TNF-alpha was correlated with IMT (r = 0.16, P < 0.05) after correction for age. Logistic regression analysis indicates a 4085 times greater chance of having retinopathy with a one unit increase in TNF-alpha (pmol/l) and a 30.64 times greater chance of having nephropathy with one unit increase in leptin (nmol/l). CONCLUSIONS: The present observations suggest that visceral and subcutaneous fat has an impact on microangiopathy as well as macroangiopathy, possibly through different adipocytokines.

Adipocytes↗
PubMed2004

Phase I study of a novel recombinant human soluble thrombomodulin, ART-123.

BACKGROUND: Anticoagulants are often given for extended periods of time to patients at high risk for venous thromboembolism, such as after orthopedic surgery. Daily subcutaneous (sc) injections can be inconvenient to the patient. A long-acting anticoagulant requiring less frequent dosing could make treatment more acceptable. Thrombomodulin is a natural anticoagulant that activates protein C, which leads to inactivation of factor (F)Va and FVIIIa and decreased thrombin formation. Recombinant human thrombomodulin is a novel anticoagulant with a long half-life in animal models. METHODS AND RESULTS: This phase I study examined pharmacokinetics, pharmacodynamics, and safety of recombinant human soluble thrombomodulin (ART-123) after administration of doses between 0.02 and 0.06 mg kg(-1) body weight intravenously (iv), and between 0.02 and 0.45 mg kg(-1) sc in 55 healthy volunteers. The plasma half-life was 2-3 days after sc injection of various single doses. Plasma ART-123 levels estimated to be needed for prevention of thrombus formation in humans were maintained for at least 6 days after single sc injection of 0.30 and 0.45 mg kg(-1) ART-123. Antithrombotic activity with these doses was demonstrated by achieving prothrombinase inhibition of more than 80% for more than 6 days after administration. No major bleeding occurred. Pharmacodynamic modeling revealed that adequate antithrombotic ART-123 levels can be achieved for 6 days with one dose of 0.45 mg kg(-1) ART-123, and for 12 days with 2 doses of 0.30 mg kg(-1), given 5 days apart. CONCLUSIONS: Recombinant human soluble thrombomodulin (ART-123) has a long half-life after sc injection and is well tolerated, making it a suitable agent to be tested in clinical thromboprophylaxis trials.

Adult↗
PubMed2004

Coronary risk factors in Kawasaki disease treated with additional gammaglobulin.

AIMS: To assess the hypothesis that an additional intravenous gammaglobulin (IVGG) infusion, if administered early, may prevent coronary artery lesions (CAL) in patients with Kawasaki disease (KD) who do not respond to initial IVGG therapy. METHODS: Forty four KD patients (17 with CAL and 27 without CAL), treated with additional IVGG because of persistent or recrudescent fever after initial IVGG therapy, were studied. Main outcome measures were the presence of CAL by echocardiography and the number of febrile days before and after start of additional IVGG infusion (pre- and post-additional IVGG). RESULTS: In univariate analyses, risk factors for CAL were the number of febrile days pre-additional IVGG, the number of febrile days post-additional IVGG, the number of days that initial IVGG was divided over, the white blood cell count pre- and post-additional IVGG, and the C reactive protein concentration pre-additional IVGG. In a multivariate analysis, the only independent risk factor was the number of febrile days pre-additional IVGG (> or =10 days; odds ratio 7.86; 95% CI 1.44 to 42.8; p = 0.02). CONCLUSIONS: Among KD patients with persistent or recrudescent fever after initial IVGG therapy, administration of additional IVGG before the first 10 febrile days was associated with a decreased prevalence of CAL, when compared with the prevalence in those who were retreated later. An additional IVGG infusion, if administered early, may prevent CAL in initial IVGG non-responders.

Adrenal Cortex Hormones↗
PubMed2004

Early pathological changes in the parkinsonian brain demonstrated by diffusion tensor MRI.

OBJECTIVE: To determine whether the fractional anisotropy (FA) of magnetic resonance diffusion tensor imaging is decreased in the nigrostriatal projection in parkinsonian patients. METHODS: FA values were compared in the extrapyramidal system of 12 patients with Parkinson's disease and eight age matched normal controls. RESULTS: Patients with Parkinson's disease had significantly decreased FA in the region of interest along a line between the substantia nigra and the lower part of the putamen/caudate complex, in which most of the nigrostriatal dopaminergic neurones are included. Loss of FA in this region was obvious even during the early clinical stages of Parkinson's disease. CONCLUSIONS: Assuming that the loss of FA parallels the neuronal change in the brain, the results are consistent with the view that more than half the dopaminergic neurones in the nigrostriatal projection are lost before the onset of Parkinson's disease. Close comparison of FA in the basal ganglia may contribute to the early diagnosis of Parkinson's disease.

Aged↗