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Biomedical subjects

K Sakamoto

Publications and source records attributed to K Sakamoto.

At least 37 records · Page 2Linked to original sources
PubMed2005

Effect of one or more co-morbid conditions on diagnostic accuracy of coronary flow velocity reserve for detecting significant left anterior descending coronary stenosis.

OBJECTIVE: To determine the effect of one or multiple co-morbid conditions on the diagnostic accuracy of coronary flow velocity reserve (CFVR) in a heterogeneous patient population. METHODS: CFVR was measured in the left anterior descending coronary artery (LAD) by transthoracic Doppler echocardiography (TTDE) in 318 consecutive patients before elective coronary angiography. CFVR was calculated as the average peak diastolic velocity during intravenous ATP infusion divided by baseline flow velocity. All patients underwent coronary angiography within 48 hours. Significant LAD stenosis was defined as > 50% luminal narrowing. Diagnostic accuracy of CFVR was analysed according to the type and number of risk factors that may adversely affect microvascular function. RESULTS: CFVR was measured in 309 patients, of whom 105 were found to have significant LAD stenosis based on coronary angiography. CFVR < 2.0 had a sensitivity of 86% and a specificity of 77% for predicting significant LAD stenosis. Left ventricular hypertrophy (LVH) was the only factor that significantly lowered diagnostic accuracy (61% with LVH v 84% without LVH, p < 0.001). Diagnostic accuracy was not affected by increasing number of risk factors. CONCLUSIONS: The diagnostic accuracy of CFVR by TTDE for detecting significant LAD stenosis remains high in a more clinically relevant population with multiple cardiovascular co-morbidities. Only the presence of LVH adversely affected diagnostic accuracy.

Adult↗
PubMed2005

Multidrug transporters in lactic acid bacteria.

Gram-positive lactic acid bacteria possess several Multi-Drug Resistance systems (MDRs) that excrete out of the cell a wide variety of mainly cationic lipophilic cytotoxic compounds as well as many clinically relevant antibiotics. These MDRs are either proton/drug antiporters belonging to the major facilitator superfamily of secondary transporters or ATP-dependent primary transporters belonging to the ATP-binding cassette superfamily of transport proteins. Here we summarize the existing data on these MDRs and discuss recent observations that suggest the use of new strategies in the ongoing battle against drug-resistant microbial pathogens.

ATP-Binding Cassette Transporters↗
PubMed2005

[Norwood procedure after colostomy; report of a case].

We encountered a baby who was diagnosed with anal atresia, interruption of aortic arch (type B), aortic stenosis, mitral stenosis, single atrium, large ventricular septal defects, aberrant origin right subclavian artery. We operated on him using the Norwood procedure after a colostomy. Aortic arch was reconstructed by interposing with an 8 mm graft and the right ventricular-pulmonary artery (RV-PA) conduit was chosen for pulmonary flow. We closed the sternum 6 days after the Norwood procedure. We extubated him 16 days after delayed sternal closure. There was no trouble with his stoma and no sign of infection. The postoperative echocardiography didn't show the finding which left pulmonary artery was stenotic, but the lung perfusion schintigraphy revealed an imbalance in the distribution of lung perfusion. He was discharged 70 days after undergoing the Norwood procedure.

Anastomosis, Surgical↗
PubMed2004

Comparison of stent placement and colostomy as palliative treatment for inoperable malignant colorectal obstruction.

BACKGROUND: Stent placement is a useful palliative treatment for inoperable acute malignant colorectal obstruction. However, data comparing stent placement with colostomy are scarce. METHODS: We compared the clinical outcome of 18 patients who had stent placement and 17 patients who underwent only colostomy. RESULTS: The postoperative hospital stay was 22.3 days for stent placement compared with 47.4 days for colostomy (p = 0.016). The duration to readmission was 129.2 days for stent placement and 188.4 days for colostomy. The estimated duration of primary stent patency was 106 days. Mean survival period was 134 days in patients with stent placement and 191 days in patients with colostomy. CONCLUSION: Postoperative hospital stay was shorter in patients with stent placement but duration to readmission and survival were longer in patients with colostomy. However, stent placement increases the option of palliative treatment and is an effective treatment contributing to improving quality of life.

Aged↗
PubMed2004

Staple line coverage with absorbable mesh after thoracoscopic bullectomy for spontaneous pneumothorax.

BACKGROUND: Thoracoscopic simple bullectomy for primary spontaneous pneumothorax (PSP) has a relatively high postoperative recurrence rate and sometimes results in postoperative air leakage. One of the reasons for postoperative recurrence is the regrowth of bullae around the staple line. Therefore, reinforcement of the visceral pleura around the staple line is a reasonable way to prevent postoperative air leaks and recurrence. This study was done to determine the efficacy in preventing postoperative air leak and recurrent pneumothorax of widely covering the staple line with absorbable mesh after thoracoscopic bullectomy. METHODS: Wide coverage of the staple line with absorbable mesh was performed on 114 patients with PSP. These patients were retrospectively compared with 126 patients who underwent thoracoscopic simple bullectomy alone. RESULTS: The postoperative duration of chest drainage in the coverage group (mean, 1 day; range, 0-5) was significantly shorter than that in the simple bullectomy group (mean, 3 days; range 0-20). A prolonged air leak (>7 days) occurred in six patients in the simple bullectomy group, but there were no such leaks in the coverage group. Recurrent pneumothorax occurred in three patients (2.6%) in the coverage group and 12 patients (9.5%) in the simple bullectomy group. CONCLUSION: Wide coverage of the staple line with absorbable mesh is effective in preventing postoperative air leak and in decreasing the recurrence rates of PSP.

Adolescent↗
PubMed2004

Electrical admittance method for estimating fluid removal during artificial dialysis.

Because the conductivity of blood changes remarkably during artificial dialysis, sometimes by more than 20%, changes in tissue admittance at low frequency are caused by changes not only in the extracellular fluid volume but also in blood conductivity. Therefore the changes in blood conductance due to artificial dialysis must be considered for the estimation of water removal by the admittance method. An accurate bio-impedance measurement system was developed. Measurement error was less than 1% at low frequency and 10% at high frequency. A new electrical bio-admittance method (NAM) was evaluated for the continuous measurement of removed fluid volume, using a three parallel-compartment tissue model, consisting of intracellular, interstitial and blood compartments, which takes into account the blood conductivity change. NAM used the equivalent conductivity calculated from the leg admittances of patients, measured at 1 min intervals during various artificial dialysis procedures. The actual amount of excess water removed by ultra-filtration agreed with the NAM-estimated amount within an error of 20%. NAM was also applied to estimate the intra- and extracellular fluid changes. The results were consistent with the physiological changes known to occur during the various forms of dialysis.

Adult↗
PubMed2004

Glucosamine, a naturally occurring amino monosaccharide, suppresses the ADP-mediated platelet activation in humans.

OBJECTIVE: To evaluate the anti-thrombotic action of glucosamine, a naturally occurring amino monosaccharide, platelets were stimulated with ADP in the presence of glucosamine, and its effects on platelet functions were examined. MATERIALS AND METHODS: Human platelet-rich plasma was stimulated with 2.5 microM ADP in the presence of glucosamine (0.01 approximately 1 mM) or other aminosugars (N-acetyl-glucosamine, galactosamine or N-acetyl-galactosamine, 1 mM), and platelet aggregation was monitored. Furthermore, the effects of glucosamine on the thromboxane A2 production, release of granule contents, intracellular calcium mobilization and phosphorylation of Syk (a 72 kD protein tyrosine kinase) were evaluated following ADP-stimulation. In addition, the binding of [3H] ADP to its receptors was examined. RESULTS: Glucosamine (>0.01 mM) dose-dependently suppressed platelet aggregation in response to ADP (p < 0.05), whereas N-acetyl-glucosamine, galactosamine or N-acetyl-galactosamine (1 mM) did not affect the ADP-induced platelet aggregation. Furthermore, glucosamine (>0.1 mM) inhibited the extracellular release of granule contents (ATP and platelet factor 4) and production of thromboxane A2 from ADP-stimulated platelets (p < 0.05). Moreover, glucosamine significantly repressed the intracellular calcium mobilization at >0.1 mM and phosphorylation of Syk at >0.01 mM upon ADP-stimulation (p < 0.05). In addition, glucosamine (>0.1 mM) inhibited the binding of ADP to its receptors (p < 0.05). CONCLUSION: Glucosamine is able to suppress platelet aggregation, release of granule constituents, thromboxane A2 production, calcium mobilization and phosphorylation of Syk possibly via the inhibition of ADP-binding to the receptors. Glucosamine could be expected as a novel anti-platelet agent for thrombotic disorders due to its suppressive actions on platelets.

Adenosine Diphosphate↗
PubMed2004

Simplified method for cryopreservation of islets using hydroxyethyl starch and dimethyl sulfoxide as cryoprotectants.

Cryopreservation is an ideal method for long-term storage of human islets. Dimethyl sulfoxide (DMSO) has been used as an intracellular cryoprotectant. However, because of its toxicity, DMSO has to be added stepwise and diluted stepwise with sucrose. We combined hydroxyethyl starch (HES) as an extracellular cryoprotectant with DMSO to simplify the freeze-thawing procedure. Islets were isolated from the pancreas of beagle dogs by an automated digestion method and Ficoll purification. After overnight culture, the islets were cryogeneically stored using cooling by a programmed freezing system. After 4-week storage in liquid nitrogen, the container was rapidly thawed in a 37 degrees C water bath. The function of the islets was assessed upon static incubation immediately after thawing, showing a recovery rate of 71.16% +/- 20.14% and a stimulation index of 1.80 +/- 0.78. In conclusion use of HES allowed a decrease in DMSO concentration and simplified the freeze-thawing procedure for islets.

Animals↗
PubMed2004

Electromyographic study of trunk muscle activity during unresisted twisting posture in various twisting angles.

The study investigated muscular activities of trunk twisting during standing posture by observing the surface EMG signal to estimate which muscles were active in graded isometric twisting posture. A laser pointer was used to maintain the twisting angle, while external resistances, which were commonly used to maintain the posture, were avoided. This procedure approached actual working posture in real life. Grading postural effort into various twisting angles provided reliable and natural posture measurements. Erector spinae (ES) at levels of L2 and L5 were selected to represent low back muscles, while external oblique (EO) and internal oblique (IO) were represented as abdominal muscles. Ten male subjects were asked to maintain a trunk twisting posture in various twisting angles for each right and left twisting direction. The EMG of the observed muscles were analyzed by power spectral density, and the activity changes were normalized by procedures of relative presentation and standardization. A Tukey multiple comparison was also applied to compare the activity changes among postural stages. Higher activity in contralateral ES, contralateral EO and ipsilateral IO is shown in the results, however, a significant increase against the initial posture (i.e., no-twisting posture) was found when the twisting angle was more than 30 degrees. Consistency with most past studies was shown in the result for the muscular activity of abdominal muscles, but not in the results for the low back muscles. The result emphasized the consideration that trunk muscle activity under a natural twisting condition was not always the same as that with the twisting under external resistance.

Abdominal Muscles↗
PubMed2004

Reduced low-density-lipoprotein cholesterol causing low serum cholesterol levels in gastrointestinal cancer: a case control study.

Several epidemiological studies suggested an inverse relation between serum cholesterol level and cancer mortality. We analyzed the relation between gastrointestinal cancers and serum cholesterol levels. A total of 631 patients were recruited as cancer-bearing cases, comprising 181 esophageal cancers, 251 gastric cancers and 199 colorectal cancers. A case-control analysis was conducted on the serum TC, HDL-C, LDL-C and TG levels. TC and LDL-C were significantly lower in cancer-bearers by approximately 15 mg/dl. Furthermore, analyses by cancer site also showed significantly lower TC and LDL-C levels in cancer-bearers than in controls for all three sites. In this analysis, early stage cancer-bearers showed a significant decrease in TC levels by approximately 11 mg/dl compared with controls, and also a similar decrease in LDL-C levels. These results suggest that low TC levels are not related to cancer stage. Furthermore, findings of no significant differences in HDL-C and TG between cancer-bearing cases and controls in addition to a specific decrease in LDL-C in cancer-bearers suggest that hypocholesterolemia observed in these cases stems from low LDL-C. However, cancer-bearers and controls showed a similar distribution of TC and LDL-C levels. We should be aware that latent cancer bearers may be present among subjects with hypocholesterolemia.

Case-Control Studies↗
PubMed2004

Cortical potentials associated with voluntary, reflex, and spontaneous blinks as bilateral simultaneous eyelid movement.

Movement-related cortical potentials (MRCPs) associated with the contraction of m. orbicularis oculi related to three types of blinks (voluntary, reflex, and spontaneous) were measured for 12 normal subjects. The purpose of the present study was to estimate the role of the cerebral cortex in close association with the blinks caused by bilateral simultaneous eyelid movements. MRCPs were recorded by surface electrodes placed over the frontal to the parietal regions. The mean amplitude and the duration of the MRCPs for the three types of blinks were evaluated by an averaging technique for each subject. MRCPs for the voluntary blinks were evoked in all subjects. For the reflex and the spontaneous blinks, however, a clear negative rising deflection from the baseline was not obtained. The maximum amplitude of the MRCPs for the voluntary blinks was localized at the vertex region, though there was no significant difference between the durations of the MRCPs for the vertex region and for the other regions. Moreover, the positive potential following the voluntary and the spontaneous blinks was recognized in the parietal region. These results suggest that only the voluntary blinks are caused by the neural activation of the supplementary motor area (SMA), and in addition, the neural activation related to visual recognition is considered to be elicited by the voluntary and the spontaneous blinks.

Adult↗
PubMed2003

Experimental model to estimate intestinal viability using charge-coupled device microscopy.

BACKGROUND: Intraoperative assessment of intestinal viability following release of strangulation remains difficult. The aim of this study was to establish clinical standards for the evaluation of intestinal viability by charge-coupled device (CCD) microscopy. METHODS: A rat ileus model with strangulation for between 15 and 120 min was used. The images obtained by CCD microscopy were used to calculate maximum velocity (V (max)) ratio (ratio of V (max) of blood cell transition in the experimental segment to that in the reference segment) and S ratio (the ratio of S-the effective area of the vascular bed against the total area of the vascular bed-in the experimental segment to that in the reference segment). Rats were divided into group 1, comprising animals that survived for 7 days or more, and group 2, which consisted of animals that died within 4 days. RESULTS: V (max) ratio and S ratio in group 1 were both significantly higher than those in group 2 (P < 0.01). No death occurred at a V (max) ratio of 0.76 or higher and an S ratio of 0.61 or more, while there were no survivors with a V (max) ratio of 0.54 or less and an S ratio of 0.51 or less. CONCLUSION: V (max) ratio and S ratio could be used as indices for evaluation of intestinal viability.

Animals↗
PubMed2003

Effects of IGF-I gene therapy on the injured rat pudendal nerve.

Injured nerves and their motor units may undergo enhanced recovery when exposed to recombinant human insulin-like growth factor-I (rhIGF-I). The external anal sphincter muscle in the female rat was denervated to model incontinence. The treatment-group muscle was injected with rhIGF-1 plasmid, whereas in the control group the plasmid lacked the cDNA insert and the normal group received neither surgery nor treatment. Electromyography data at 56 days post surgery indicated more reinnervation without fibrillation potentials in the treatment group (2 of 6) than in the control group (0 of 6). The histology of the regenerated axons in the pudendal nerve distal to the crush site also suggested an improved recovery in the treatment group. The number of motor neurons retrogradely labeled with horseradish peroxidase was decreased by 50% following pudendal nerve crush in both experimental groups compared to the normal group. We conclude from these preliminary results that rhIGF-I gene therapy may improve the distal recovery of structure and function.

Anal Canal↗
PubMed2003

Prostaglandin E2 induced the differentiation of osteoclasts in mouse osteoblast-depleted bone marrow cells.

Prostaglandin (PG) E(2) is a known bone absorbing agent that acts on osteoblasts to facilitate osteoclastogenesis by increasing the secretion of RANKL. In the present study, we investigated the direct action of PGE(2) on osteoclastic progenitors that differentiate into TRAP-positive multinucleated cells. The hematopoietic stem cell obtained from murine bone marrow was purified by a Sephadex G-10 column, and cultured in the presence of CSF-1 and RANKL to facilitate cell differentiation. The introduction of low-density PGE(2) into the culture resulted in a drastic increase of TRAP-positive multinucleated cells, whereas the addition of high-density PGE(2) had the opposite effect. PCR analysis revealed increased level of EP3 mRNA in undifferentiated cells and reduced level after the development of osteoclast; EP1, EP2 and EP4 were constitutively expressed throughout the differentiation. Investigation of intracellular signaling verified that low-density PGE(2) suppressed PKA activity in undifferentiated cells, suggesting that PGE(2) acts on the osteoclastic cell lineage to facilitate cell differentiation by suppressing PKA in the presence of RANKL.

Animals↗
PubMed2003

[Torsion of the middle lobe after right upper lobectomy of the lung; report of a case and the review of the Japanese literatures].

We report a case of torsion of the residual right middle lobe of the lung, following right upper lobectomy for lung cancer. A 71-year-old man who had medical treatment for emphysema was admitted with a lung tumor on chest computed tomography. The tumor was diagnosed as pulmonary adenocarcinoma by transbronchial biopsy. Right upper lobectomy with mediastinal lymph node dissection, and partial resection of the right lower lobe were performed. On the following day, chest X-ray showed an opacification in the right upper lung field, which gradually increased. Bronchoscopic examination revealed a stenotic middle lobe bronchus. Torsion of the middle lobe was suspected, and rethoracotomy was performed on the second postoperative day. The middle lobe was torsed 90-degree counterclockwise around its bronchovascular pedicle. A middle lobectomy was performed secondary to severe congestion. The patient was discharged in good condition on the 11th postoperative day. In reviewing the literatures including this case, 13 of 16 torsions occurred after right upper lobectomy of the lung. Thirteen patients had rethoracotomy, 10 of them underwent resection of the rotated lung. Simple detorsion was carried out in 3 patients, and 1 of them developed cerebral infarction. Lung torsion was reported to be potentially life-threatening. Therefore, fixation of a remaining lobe should be performed. Exploratory thoracotomy should be performed without delay, if lung torsion is suspected.

Adenocarcinoma↗
PubMed2003

[New surgical approach "intrapulmonary septation technic" for Fontan candidates with unilateral pulmonary arterial hypoplasia and/or pulmonary venous obstruction].

Unilateral pulmonary arterial hypoplasia and/or pulmonary venous obstruction are serious hazards for Fontan candidates. For these patients, we have started new surgical approach "intrapulmonary septation technic". This consists of 3 components; (A) partial right heart bypass to well-grown side, (B) mandatory pulmonary blood flow to low-capacity side, (aorto-pulmonary shunt or others) and (C) a patch between partial right heart bypass and mandatory pulmonary blood flow. Thirteen patients underwent the approach. The source of partial right heart bypass was brought from superior vena cava (11 patients), inferior vena cava (1 patient) and fenestrated Fontan (1 patient). The mandatory pulmonary blood flow was supplied by aorto-pulmonary shunt (11 patients), pulmonary arterial banding (1 patient) and native pulmonary valve stenosis (1 patient). We added pulmonary artery enlargement (9 patients), release of pulmonary venous obstruction (8 patients) and/or atrio-ventricular valve plasty (5 patients), simultaneously. No hospital death. Early post-operative course was uneventful in all cases except 1, as pulmonary blood flow to low-capacity side had increased gradually after this intervention. Eight patients had reached Fontan operation. In this approach, nearly whole pulmonary artery can grow without any affect of volume overload through well-grown side from collateral arteries of low-capacity side. All procedures of "intrapulmonary septation technic" and reconstruction of pulmonary artery in Fontan operation can be easily performed in larger pulmonary artery of well-grown side, eliminating need for extensive dissection.

Child↗