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Biomedical subjects

K Sakamoto

Publications and source records attributed to K Sakamoto.

At least 55 records · Page 3Linked to original sources
PubMed2003

EMG characteristics of low back and lower limb muscles during forward bending posture.

The study observed forward bending posture and evaluated its effect on muscular activity. The Muscular activity was monitored through the Electromyography (EMG). The objective was to extend the evaluation method of EMG due to muscular load in maintaining the posture and to investigate the existence of muscular coordination between low back and lower limb muscles during the posture. Twelve male subjects were asked to maintain the postures of six stages in bending angles from 0 to 180 degrees. The EMG of erector spinae (ES) at L1 and L5 levels, hamstrings, and gastrocnemius were recorded and analyzed by power spectral density. The characteristics of muscular activities were observed through the EMG power spectrum and the frequency. The activity changes were normalized by the relative presentation and the standardization. The relative presentation showed the level of activity changes in each posture by taking the activity during upright standing as a reference posture, and the standardization was applied to overcome the dependence of the power spectrum and the frequency upon the high standard deviation. A t test with the paired data was also applied to compare the values of EMG of the respective stages of the posture. The results showed that the activity of ES significantly increased during bending posture with an angle up to 45 degrees, and reached silent activity at 90 degrees of flexion. On the other hand, the activity of the hamstrings and gastrocnemius were recognized even when ES activity started and reached the silent activity. The lower limb muscles were considered to be always active during all stages of the posture, and they provided a greater contribution when the ES was in the silent activity.

Adult↗
PubMed2002

Methyl isobutyl ketone and methyl ethyl ketone in urine as biological markers of occupational exposure to these solvents at low levels.

OBJECTIVE: To examine whether unmetabolized methyl isobutyl ketone in urine is a useful marker of low-level occupational exposure to this ketone solvent, as is the case for methyl ethyl ketone. METHODS: The study was conducted in the second half of a working week. In total, 27 furniture-making workers (19 men and eight women) and 11 non-exposed controls (six men and five women) volunteered to participate in the study. Time-weighted average (TWA; 8-h) concentration of vapors of several solvents in air, including methyl isobutyl ketone (MIBK-A) and methyl ethyl ketone (MEK-A) was monitored by diffusive sampling. Urine samples collected at the end of the shift were subjected to head-space gas chromatography (GC) analysis for the unmetabolized solvents (i.e., MIBK-U and MEK-U). The relationship between the concentration of the solvent vapor and the corresponding solvent level in urine was examined by simple as well as multiple regression analysis. RESULTS: The exposures to MIBK and MEK were well below the current occupational exposure limit levels, but the maximum levels of exposure to toluene and ethylbenzene were around the corresponding exposure limit. The correlation of the TWA concentration of the solvent in air with the concentration of the corresponding solvent in the end-of-shift urine sample was significant both for MIBK and for MEK, and the correlation coefficient was larger for MIBK than for MEK. The slope in the exposure-excretion regression line was almost twice as steep for MEK than for MIBK, possibly due to the difference in water solubility. Approximately 0.12% of MIBK absorbed in the lungs will be excreted into urine, whereas the yield for MEK was somewhat higher (0.19%). CONCLUSION: MIBK in urine is a good marker of exposure to MIBK, as in the case of MEK in urine for MEK exposure.

Adult↗
PubMed2002

Evaluation of the tissue reactions in the skin and body wall of koi (Cyprinus carpio) to five suture materials.

Five different suture materials (silk, monofilament nylon, polyglyconate, polyglactin 910, and chromic gut) were placed in the skin and body wall of 10 Doitsu (scaleless) koi (Cyprinus carpio). After seven days the sutures were retrieved from five of the fish in 5 mm and 6 mm punch biopsies, and after 14 days they were retrieved in the same way from the other five. The tissue reactions were evaluated by gross visual inspection and by histological examination. The total inflammatory reaction was graded on a scale from 0 (no inflammation) to 5 (severe inflammation). The synthetic suture materials generally induced a moderate inflammatory reaction that decreased after seven days. After 14 days the superficial reaction to monofilament nylon was substantial, and the tissue reactions to the organic suture materials were slightly greater than the reactions to the synthetics. The inflammatory response to silk was greater after 14 days than after seven, and chromic gut induced a moderately severe inflammatory response after seven days; the chromic gut sutures fell out before the biopsies were taken after 14 days. The organic materials induced intense inflammatory reactions which did not subside if the suture remained in the tissue.

Animals↗
PubMed2002

Toluene, xylenes and xylene isomers in urine as biological indicators of low-level exposure to each solvent; a comparative study.

OBJECTIVE: To examine if xylenes and xylene isomers in end-of-shift urine are good biological indicators of low-level exposure to each solvent, similarly to toluene in urine. METHODS: The study was conducted in the latter half of a working week. Furniture makers, 86 subjects in total (76 men and ten women), participated in the study in combination with 11 non-exposed subjects. Time-weighted average (8-h TWA) exposures to mixtures of toluene (TOL-A), xylenes (XYLs-A), ethylbenzene (EB-A), acetone (ACE-A) etc. were monitored with diffusive samplers for lipophilic and hydrophilic solvents, respectively. Urine samples (i.e., TOL-U, XYLs-U, EB-U, ACE-U, etc.) were collected at the end of the shift and subjected to head-space gas chromatography analysis for each solvent. The exposure-excretion relationship was examined by simple as well as multiple regression analysis. RESULTS: The exposures to TOL and XYLs were around or below current occupational exposure limit levels. The exposures to other solvents [i.e., ACE, EB, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), etc.] were at substantially lower levels. The correlation of the TWA solvent exposure concentration with the concentration of the corresponding solvent in the end-of-shift urine sample was close for TOL, and also almost equally close in the case of XYLs and each of the three XYL isomers. Whereas the slope of the regression line for XYLs was significantly less steep than that for TOL when compared on an equi-molar basis, there was no difference among the three XYL isomers. No confounding effects of age, sex and co-exposure to other solvents were detected. The observation confirms previous reports that TOL-U is a good marker of TOL vapor exposure, indicates that XYL-U is also a reliable marker of exposure to vapors of XYLs or any of the three XYL isomers, and suggests that estimation of exposure to vapors of XYLs (i.e., three isomers in combination) is possible by the determination of one of the XYL isomers in urine, once the proportion of the isomers in air is known. Possible association of water solubility with solvent levels in urine is discussed. CONCLUSIONS: Biological monitoring of exposure by means of analysis of end-of-shift urine for mother solvent is possible, not only in the case of TOL as previously reported, but also in cases of XYLs, either for three isomers in combination or separately.

Adult↗
PubMed2002

Recent outbreaks of foot and mouth disease in countries of east Asia.

Japan regained the status of freedom from foot and mouth disease (FMD) without vaccination in September 2000 and the Republic of Korea likewise obtained this status in September 2001. However, new outbreaks of FMD caused by the pan-Asian topotype have occurred in pigs in the Republic of Korea since May 2002. Taipei China has not experienced an outbreak of FMD since February 2001 and the country is currently implementing an eradication programme. These countries had been free from FMD for many decades when in 1997, the FMD virus (FMDV) once again invaded the region, particularly in 2000; this resulted in widespread occurrence of the disease. The types of FMDV were investigated by genome analysis, and in each case the virus concerned was found to be a member of the pan-Asian O lineage. The authors present the recent situations and the characteristics of FMD in countries of east Asia.

Animals↗
PubMed2002

[Mid-term outcome of aortic arch operation for true aneurysms; using an axillary artery perfusion].

To prevent cerebral infarction during perioperative period, we have used an axillary artery for systemic perfusion and selective cerebral perfusion for aortic arch operation. Since 1996, 34 aortic arch operations were performed in our institution. Simultaneous 5 CABGs, 4 AVRs, 2 aortic root replacements and 1 MVR were performed. There were 2 hospital deaths (5.9%, sepsis and acute heart failure) and only 1 (2.9%) cerebral infarction. There were no deaths in patients over 75 years of age and in patients with extensive aneurysm which were replaced by 2-staged operation. Overall 3 years survival was 94.1% with no further death. We conclude that aortic arch operation through an axillary artery perfusion and with hypothermic selective cerebral perfusion can be performed with very low mortality and morbidity.

Adult↗
PubMed2002

Evaluation of postural tremor of finger for neuromuscular diseases and its application to the classification.

The purpose of this study is to verify the features of the power spectrum of postural tremors for neuromuscular disease patients and to classify the postural tremors. The subjects were 88 neuromuscular disease patients (30 Parkinson disease (PD), 25 cerebellar disease (CER), 7 multiple sclerosis (MS), 7 neuropathy (NEU), 10 motor neuron disease (MND), 9 myopathy (MYO)). The control subjects were 12 normal young persons and 10 normal aged persons. Postural tremor was detected by accelerator sensor. Postural tremor was recorded under the two postural conditions: The subjects maintained the index finger without or with a weight load of 50 g in a horizontal position while looking at a visual target in front of the tip of the index finger. The power spectrum was calculated by an auto-regressive model (AR model). The peak frequency and the peak power were evaluated under the two conditions. Two frequency components of 8-12 Hz and 20-25 Hz appeared in the postural tremor of both normal subjects and neuromuscular disease patients. The difference of the postural tremor between the subjects mainly appeared in the 8-12 Hz component during the postural tremor with a weight load. MYO patients belonged to one group (called as group P1) due to lower peak power, CER patients belonged to one group (called as group P2) due to higher peak power, and PD and MS patients belonged to one group (called as group P3) due to lower peak frequency and higher peak power. NER and MND patients belonged to one group (called as group N which meant normal group). These results suggested that the peak frequency and the peak power of the 8-12 Hz component were changed by the conditions of both spinal reflex system and central nervous system. An oscillator within the central nervous system produced the underlying frequency of 8-12 Hz component, while the amplitude of 8-12 Hz component was governed by both spinal reflex system and central nervous system. In conclusion, the classification of postural tremor for neuromuscular disease patients was a useful index to elucidate the mechanism of tremor oscillation and to assist in clinical diagnosis of neuromuscular disease.

Adult↗
PubMed2002

[Thoracoscopic pericardial fenestration for persistent pericardial effusion after radiotherapy for esophageal cancer; report of a case].

We performed thoracoscopic pericardial fenestration for persistent pericardial effusion after radiotherapy for esophageal cancer. An 85-year-old man who had radiation therapy (70.2 Gy) for esophageal cancer was admitted for shortness of breath. Chest computed tomography showed a pericardial effusion. During the 6 months prior to this admission, the patient had undergone percutaneous pericardial drainage 3 times for cardiac tamponade. We performed thoracoscopic partial pericardiectomy with creation of a pleuropericardial window via one access port. Histopathologically, no malignant cells were found in either the resected pericardium or the pericardial effusion. Therefore, we believe the persistent pericardial effusion was secondary to radiotherapy. There was no recurrence of the pericardial effusion for 7 months postoperatively. In summary, thoracoscopic pericardial fenestration is useful in both the diagnosis and treatment of persistent pericardial effusion.

Aged↗
PubMed2001

Lactone-ring-cleaving enzymes of microorganisms: their diversity and applications.

Microbial lactonohydrolases (lactone-ring-cleaving enzymes) with unique characteristics were found. The Fusarium oxysporum enzyme catalyzes the reversible and stereospecific hydrolysis of aldonate lactones and D-pantolactone (D-PL), and is useful for the optical resolution of racemic PL. The Agrobacterium tumefaciens enzyme hydrolyzes several aromatic lactones, and catalyzes the stereospecific hydrolysis of PL like the Fusarium enzyme, but its selectivity is opposite. The Acinetobacter calcoaceticus enzyme catalyzing the specific hydrolysis of dihydrocoumarin belongs to serine-enzyme family, and is useful for enantioselective hydrolysis of methyl DL-beta-acetylthioisobutyrate and regioselective hydrolysis of methyl cetraxate. This enzyme also catalyzes the bromination of monochlorodimedon when incubated with H(2)O(2) and dihydrocoumarin.

Acinetobacter calcoaceticus↗
PubMed2001

Malonyl-CoA decarboxylase is not a substrate of AMP-activated protein kinase in rat fast-twitch skeletal muscle or an islet cell line.

The AMP-activated protein kinase (AMPK) plays an important role in fuel metabolism in exercising skeletal muscle and possibly in the islet cell with respect to insulin secretion. Some of these effects are due to AMPK-mediated regulation of cellular malonyl-CoA content, ascribed to the ability of AMPK to phosphorylate and inactivate acetyl-CoA carboxylase (ACC), reducing malonyl-CoA formation. It has been suggested that AMPK may also regulate malonyl-CoA content by activation of malonyl-CoA decarboxylase (MCD). We have investigated the potential regulation of MCD by AMPK in exercising skeletal muscle, in an islet cell line, and in vitro. Three rat fast-twitch muscle types were studied using two different contraction methods or after exposure to the AMPK activator AICAR. Although all muscle treatments resulted in activation of AMPK and phosphorylation of ACC, no stimulus had any effect on MCD activity. In 832/13 INS-1 rat islet cells, two treatments that result in the activation of AMPK, namely low glucose and AICAR, also had no discernable effect on MCD activity. Last, AMPK did not phosphorylate in vitro either recombinant MCD or MCD immunoprecipitated from skeletal muscle or heart. We conclude that MCD is not a substrate for AMPK in fast-twitch muscle or the 832/13 INS-1 islet cell line and that the principal mechanism by which AMPK regulates malonyl-CoA content is through its regulation of ACC.

AMP-Activated Protein Kinases↗
PubMed2001

betac cytokine receptor-induced stimulation of cAMP response element binding protein phosphorylation requires protein kinase C in myeloid cells: a novel cytokine signal transduction cascade.

We have recently shown that IL-3R occupancy activates a phosphatidylcholine-specific phospholipase C, and the sustained diacylglycerol accumulation subsequently activates protein kinase C (PKC). In human IL-3-dependent myeloid cells (TF-1), the novel PKCepsilon isoform regulates bcl-2 expression and cell survival. The report of a PKC activatable cAMP response element (CRE) in the bcl-2 promoter and a role for PKC in bcl-2 expression in B cells led us to the hypothesis that PKC phosphorylation activates transcription factor CREB after IL-3R engagement. We found that IL-3 and GM-CSF induced phosphorylation of CREB on Ser(133) in TF-1 cells, and this phosphorylation was blocked by two structurally unrelated classes of PKC inhibitors. An inhibitor of cyclic nucleotide-dependent kinases did not block this phosphorylation. IL-4, which is biologically active in these cells but does not use the beta common subunit, did not phosphorylate CREB on Ser(133). Inhibition of mitogen-activated protein kinase kinase activity also inhibited IL3-induced CREB phosphorylation. The PKC inhibitors, but not a cyclic nucleotide-dependent kinase inhibitor, blocked IL-3 activation of CRE-dependent transcription from an egr-1 promoter/chloramphenicol acetyltransferase (CAT) reporter construction transiently transfected into TF-1 cells. Finally, TF-1 cells stably overexpressing PKCepsilon, but not the delta isoform of PKC, enhanced CRE-dependent CAT expression from the promoter/reporter construction. Therefore, it is likely that a PKCepsilon kinase cascade resulting in CREB phosphorylation represents a novel signal transduction cascade for regulating cellular gene expression through the beta common cytokine receptor.

Amides↗
PubMed2001

Long-term assessment of posttransplant renal prognosis with 31 P magnetic resonance spectroscopy.

BACKGROUND: 31P-magnetic resonance spectroscopy (MRS) has been widely used to study pretransplantation renal viability, and although some had discussed posttransplant renal viability, no one has examined long-term posttransplant renal prognosis. We discuss the use of 31P-MRS to assess the long-term prognosis from the time when MRS was performed. METHODS: We studied 20 patients with renal allografts. 1.5 Tesla clinical magnetic resonance imaging (MRI) and 15 cm surface coil was used for 31P-MRS. Localized 31P-MRS was done using image selected in vivo spectroscopy (ISIS) method. Individual peaks were fitted by Lorenzian line-shapes with a least square method and peak area ratios were calculated. RESULTS: A beta-adenosine triphosphate/inorganic phosphate (beta-ATP/Pi) ratio >1.2 had sensitivity of 92.8%, specificity of 100%, and accuracy of 95% for predicting 3-year renal survival; a beta-ATP/Pi ratio >1.2 had sensitivity of 90.9%, specificity of 66.7%, and accuracy of 76.9% for predicting 5-year renal survival. We compared 31P-MRS spectra data between the survived group and failed group. The survived group had significantly higher beta-ATP/Pi, alpha-ATP/Pi, and phosphodiester (PDE)/Pi ratios than the failed group. CONCLUSIONS: We discussed the beta-ATP/Pi value as a parameter for predicting long-term survival of a transplanted kidney from the time when MRS was performed. A value above 1.2 suggests a high probability of 3-year renal survival, whereas a value over 2.5 indicates that the transplanted kidney could survive over 5 years. 31P-MRS may be useful for predicting long-term survival of transplanted kidneys, but additional studies are needed.

Adult↗
PubMed2001

The muscle-specific protein phosphatase PP1G/R(GL)(G(M))is essential for activation of glycogen synthase by exercise.

In skeletal muscle both insulin and contractile activity are physiological stimuli for glycogen synthesis, which is thought to result in part from the dephosphorylation and activation of glycogen synthase (GS). PP1G/R(GL)(G(M)) is a glycogen/sarcoplasmic reticulum-associated type 1 phosphatase that was originally postulated to mediate insulin control of glycogen metabolism. However, we recently showed (Suzuki, Y., Lanner, C., Kim, J.-H., Vilardo, P. G., Zhang, H., Jie Yang, J., Cooper, L. D., Steele, M., Kennedy, A., Bock, C., Scrimgeour, A., Lawrence, J. C. Jr., L., and DePaoli-Roach, A. A. (2001) Mol. Cell. Biol. 21, 2683-2694) that insulin activates GS in muscle of R(GL)(G(M)) knockout (KO) mice similarly to the wild type (WT). To determine whether PP1G is involved in glycogen metabolism during muscle contractions, R(GL) KO and overexpressors (OE) were subjected to two models of contraction, in vivo treadmill running and in situ electrical stimulation. Both procedures resulted in a 2-fold increase in the GS -/+ glucose-6-P activity ratio in WT mice, but this response was completely absent in the KO mice. The KO mice, which also have a reduced GS activity associated with significantly reduced basal glycogen levels, exhibited impaired maximal exercise capacity, but contraction-induced activation of glucose transport was unaffected. The R(GL) OE mice are characterized by enhanced GS activity ratio and an approximately 3-4-fold increase in glycogen content in skeletal muscle. These animals were able to tolerate exercise normally. Stimulation of GS and glucose uptake following muscle contraction was not significantly different as compared with WT littermates. These results indicate that although PP1G/R(GL) is not necessary for activation of GS by insulin, it is essential for regulation of glycogen metabolism under basal conditions and in response to contractile activity, and may explain the reduced muscle glycogen content in the R(GL) KO mice, despite the normal insulin activation of GS.

Animals↗
PubMed2001

Suppression of protein kinase C signaling by the novel isoform for bovine PGF(2alpha) receptor.

A cDNA clone for a novel isoform of prostaglandin (PG) F(2alpha) receptor (FP) was isolated from the cDNA pool of the bovine corpus luteum. The sequence analysis revealed that the new FP isoform (FP(a)) encodes a 295-amino acid protein carrying a specific 28-amino acid sequence from the middle of transmembrane segment VI to the carboxyl terminus. Because only one copy gene has been identified for FP, FP(a) was generated by alternative mRNA splicing at the middle of the VI transmembrane region, resulting in the lack of a VII transmembrane segment and an intracellular carboxyl tail. The RT-PCR analysis for FP and FP(a) indicated that both mRNAs are expressed similarly during the estrous cycle and pregnancy. The PGF(2alpha) stimulation drastically enhanced protein kinase C (PKC) activity in the COS-7 cell transfected with FP, whereas no PKC activation was detected in FP(a)-transfected cells. Cotransfection of an excess amount of FP(a) markedly reduced FP-mediated PKC activity, suggesting that the novel FP isoform might play a role as a negative regulator to attenuate normal FP function.

Amino Acid Sequence↗
PubMed2001

Reactive oxygen species up-regulates cyclooxygenase-2, p53, and Bax mRNA expression in bovine luteal cells.

Reactive oxygen species (ROS) are well-established modulators of luteal cell apoptosis in the estrous cycle. The objective of this study was to clarify the molecular mechanisms of luteolysis by characterizing the levels and regions of mRNAs involved in ROS-induced luteal cell apoptosis. Stimulation of bovine luteal cells by H2O2 resulted in the induction of apoptotic nuclear condensation and Caspase-3 activation. In addition, a marker for oxidative stress-damaged DNA, 8-hydroxy-2'-deoxyguanosine, was highly accumulated in the large luteal cells prepared from the late estrous stage. Reverse transcription polymerase chain reaction and Northern blot analysis demonstrated that mRNAs of cyclooxygenase (COX)-2, p53, and Bax were highly accumulated in the H2O2-treated cells. In situ hybridization revealed that these mRNAs were most abundantly expressed in the large luteal cells. These findings suggest that enhancement of ROS in the bovine corpus luteum induces expression of COX-2, p53, and Bax mRNAs, resulting in activation of the signaling pathway for luteal-cell apoptosis.

8-Hydroxy-2'-Deoxyguanosine↗