Biomedical subjects

Y Shimada

Publications and source records attributed to Y Shimada.

At least 325 records · Page 18Linked to original sources

PubMed1996

Embolization of cerebral aneurysms with a liquid embolus, EVAL mixture: report of three cases.

Embolization of three surgically difficult cerebral aneurysms was performed using our newly developed non-adhesive embolic material, EVAL mixture (ethylene vinyl alcohol copolymer). Conventional embolic materials such as detachable balloons or microcoils were not used because of a large or irregular aneurysmal neck. After temporary occlusion of the parent artery with a superselective balloon catheter, the EVAL mixture was slowly injected through a microcatheter placed in the aneurysm or parent artery. The locations of the aneurysms were anterior communicating artery, basilar artery-posterior cerebral artery and basilar artery-anterior inferior cerebellar artery (BA-AICA). One aneurysmal occlusion and 2 parent artery occlusions were performed. Patients had no persistent deficits. The patient with the BA-AICA aneurysm associated with an arteriovenous malformation died of rupture of the residual AVM due to haemodynamic change 2 weeks after embolization. In selected and limited cases, embolization of surgically difficult cerebral aneurysms using EVAL mixture was more effective and safer than embolization using conventional embolic materials such as balloons and microcoils.

Adult↗

PubMed1996

Alteration of T cells and natural killer cells during chickenpox in infancy.

To determine the reasons for the low immune response and the mild morbidity of chickenpox in infancy, we investigated alteration of T cells and natural killer (NK) cells during chickenpox in children < 1 year and > or = 2 years old using flow cytometry. The CD4/CD8 ratio decreased only in the < 1-year-old group from the acute to the convalescent phase (P < 0.05). The CD3-CD16+CD56+ and CD57-CD16+ counts increased in the < 1-year-old group, but those in the > or = 2-year-old group did not increase from the acute to the convalescent phase. The CD3-CD16+CD56+ counts and the CD57-CD16+ counts and percentage were larger in the < 1-year-old group than those in the > or = 2-year-old group (P = 0.001, P = 0.002, and P < 0.05) in the convalescent phase. These results seem to indicate that the low immune response in infancy after chickenpox are related to the small number of CD8 in contrast with CD4 and that increased subsets of NK cells during chickenpox may correlate to the mild morbidity of chickenpox in infancy.

Acute Disease↗

PubMed1996

Spinal subdural hematoma.

We report the case of a 68-year-old patient with a traumatic spinal subdural hematoma. MRI demonstrated an area of abnormal intensity and a black line in the inner part of the intradural space. We anticipate that MRI will help to make one more confident in the preoperative diagnosis of spinal subdural hematoma. The symptoms completely disappeared immediately after the operation. Spinal subdural hematoma requires immediate surgical evacuation. The prognosis for functional recovery is good if the condition is appropriately diagnosed and treated before development of irreversible paralysis. We recommend MRI to make an early diagnosis and early evacuation of spinal subdural hematoma.

Aged↗

PubMed1996

Effects of different inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, pravastatin sodium and simvastatin, on sterol synthesis and immunological functions in human lymphocytes in vitro.

It has been shown previously that 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (HMG-CoA RIs) such as compactin and lovastatin suppress human lymphocyte functions in vitro (Cuthbert and Lipsky, 1981; Cutts and Bankhurst, 1989). Although it is not fully understood what inhibitory role the HMG-CoA RIs perform in causing this suppression, we show in this study that a certain inhibition threshold (inhibition level > 90%) of lymphocytic HMG-CoA reductase is required for the HMG-CoA RIs to attain effective inhibitory action in human lymphocyte lymphocyte functions in vitro. Thus the inhibitory activity of simvastatin, a lipophilic inhibitor, on sterol synthesis (HMG-CoA reductase activity) in lymphocytes was as much as 430 times more potent than that of pravastatin sodium, a hydrophilic inhibitor (IC50; 0.013 microM and 5.6 microM, respectively), and although pravastatin sodium and simvastatin at concentration levels of 10 and 0.016 microM respectively, inhibited the sterol synthesis in just over 50%, they failed to inhibit the lymphocyte functions. Significant inhibition (P < 0.01) of lymphocyte functions, including lymphocyte proliferative response to a variety of stimuli and activated natural killer-cell cytotoxicity, was demonstrated only when greater than 90% of the sterol synthesis in lymphocytes was inhibited by either simvastatin or simvastatin sodium salt at concentrations above 2 microM. This simvastatin-induced inhibition of lymphocyte functions was almost completely reversed by the addition of a 1 mM solution of mevalonate. Although simvastatin at a lower clinical blood concentration of 0.016 microM failed to inhibit either lymphocyte functions or HMG-CoA reductase activity sufficiently, at this level it caused a significant increase in cyclosporin A-induced suppression of T-cell response. These results infer that insufficient inhibition (in the 50% region) of HMG-CoA reductase activity by a low clinical blood concentration of HMG-CoA RIs, could still render the lymphocytes susceptible to immunosuppressive treatments. Pravastatin sodium on the other hand, is inactive in inhibiting lymphocyte functions in vitro, and such inactivity can be explained solely of the basis of its failure to inhibit HMG-CoA reductase activity in lymphocytes sufficiently.

Cyclosporine↗

PubMed1996

A quantification of goldfish behavior by an image processing system.

We developed a computer-image processing system to quantitatively score the goldfish behavior. The system was composed of two CCD cameras, set in the upper and side directions of a water tank, two graphics I/O boards (video interface) and an IBM PC/AT compatible computer. From the top and side views through the two CCD cameras, 2-dimensional or 3-dimensional positional coordinates of fish freely moving in an aquarium were acquired over a long period (60 min). A positional distribution histogram of the goldfish was made by measuring the number of coordinates. Goldfish have a tendency to move at the circumference and bottom of a water tank. The velocity of moving goldfish was calculated from the time and distance. The average velocity of goldfish was in the range of 6-36 mm/s. A directional histogram (go straight and turn right or left) of a moving goldfish in an aquarium was made to measure an angle formed by two vectors, which were defined as three (middle to terminal against initial to middle) points in a unitary length (50 mm) of the path of goldfish. Three directions (go straight, right turn and left turn) were quantified as a percentage (59 +/- 12%, 20 +/- 4% and 20 +/- 4%, respectively) of a 1-h-event of moving goldfish. This image processing system thus can make an easy and quantifiable behavioral analysis of moving goldfish.

Algorithms↗

PubMed1996

Efficacy of CPT-11 (irinotecan) as a single agent in metastatic colorectal cancer.

The efficacy of CPT-11 (Campto, irinotecan) given as a single agent has been assessed in three phase II clinical studies of patients with advanced colorectal cancer conducted in Japan, Europe and the U.S. Among a total of 337 evaluable patients treated with CPT-11 in dosage schedules of 100-150 mg/m2 weekly or bi-weekly (Japan, n = 63; U.S., n = 118) or 350 mg/m2 every 3 weeks (Europe, n = 156), overall objective response rates ranged from 17 to 27% and the median duration of response was approximately 7-9 months. Prior treatment with chemotherapy did not preclude a response to CPT-11 as evidenced by response rates of 14 to 22% and response durations of approximately 6-8 months in this cohort. In the European study, comparison of chemotherapy-naive patients with those who had received only one 5-fluorouracil (5-FU)-based regimen revealed similar response rates (22 and 20%) and of note, CPT-11 maintained its activity in pretreated patients who had previously experienced progressive disease. Together, these results suggest a lack of cross-resistance between the two agents. Leucopenia and delayed diarrhoea were the major adverse events observed in these studies, with grade 3-4 events occurring in 15-36% and 13-47% of patients, respectively. CPT-11, therefore, has significant activity in advanced colorectal cancer with response rates that are reproducible, durable and comparable to those achieved with 5-FU plus folinic acid in the first-line treatment of metastatic disease. Further work is needed to define the optimum dosage schedule for CPT-11 and also to assess fully the utility of CPT-11 in combination with other chemotherapeutic agents. Nevertheless, the activity of CPT-11 in patients refractory to treatment with 5-FU may be considered a significant advance, making it the first effective second-line agent in this setting.

Adolescent↗

PubMed1996

CPT-11 (irinotecan) and 5-fluorouracil: a promising combination for therapy of colorectal cancer.

CPT-11 (Campto, irinotecan) is a new topoisomerase I inhibitor and one of very few new cytotoxic agents to demonstrate clinical activity in colorectal cancer since the introduction of 5-fluorouracil (5-FU) into clinical practice almost 40 years ago. Because of the unique mechanism of action of CPT-11, its proven activity in colorectal cancer, and its lack of cross-resistance with 5-FU, the combination of CPT-11 with 5-FU is a logical approach to attempt to improve on the results obtained with CPT-11 or 5-FU-based treatments alone. Various administration schedules of CPT-11/5-FU combinations have been investigated in phase I studies in Japan, the U.S. and Europe. Preliminary results indicate that concurrent administration of substantial doses of CPT-11, 5-FU and folinic acid is feasible in terms of safety. Preliminary analysis of controlled pharmacokinetic data suggests that 5-FU has no substantial effect on the metabolism of CPT-11 to its active metabolite SN-38. Major objective responses and other indicators of clinical activity have been observed with the combination in both chemotherapy-naive and pretreated patients with colorectal cancer. Studies are ongoing to define fully optimum dosage schedules of CPT-11/5-FU combinations, and some of these schedules will soon enter phase II and III clinical trials. It is hoped that such a combination will prove to be an important advance in the treatment of colorectal cancer.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1996

Clinical use of percutaneous intramuscular electrodes for functional electrical stimulation.

OBJECTIVE: To evaluate the clinical use of the percutaneous intramuscular electrode in functional electrical stimulation (FES). DESIGN: Randomized and controlled study. SETTING: A referral center and institutional practice providing outpatient care. PATIENTS: Seventeen patients (12 men, 5 women) who had implanted percutaneous intramuscular electrodes for more than 1 year were examined. The average follow-up time after implantation of electrodes was 2.2 years (range, 1yr to 4yr 10mo). Overall, there were 327 electrodes (83 upper extremities and 244 lower extremities). INTERVENTION: The indwelling electrode was composed of helically coiled Teflon-coated rope stranded from 19 hard drawn wires of SUS 316L stainless steel (SES 114). MAIN OUTCOME MEASURES: The rates of breakage, movement, and infection, and the number of electrodes that needed reimplantation were evaluated. RESULTS: Only one electrode broke (0.3%) in the iliopsoas muscle at 12 weeks after implantation. Eight electrodes (2.4%) were removed because of loss of sufficient contraction force caused by movement of the electrodes. Movements occurred at 9 weeks in 6 electrodes and at 5 months in two. The failure rate of electrodes in the lower extremities was 3.7%. No failures occurred in the upper extremities. Ten electrodes (3.1%) required reimplantation. Although ten superficial infections (3.1%) were seen around the site of electrode insertion, no removals of electrode were needed. All electrodes in one patient were removed, however, because of generalized methicillin-resistant Staphylococcus aureus infection complicated with renal disease. Electrodes were reimplanted after improvement of the infection. CONCLUSIONS: The ultrafine percutaneous intramuscular electrode was considered practical for long-term FES use.

Adult↗

PubMed1996

An electrical knee lock system for functional electrical stimulation.

An electrical knee lock system that can be combined with functional electrical stimulation was designed for paraplegic patients. This knee system unlocks the knee electrically and allows knee flexion during the swing phase of the gait. When the knee is extended by electrical stimulation of the knee extensors, the knee is automatically locked by the weight of the locking bar, and the stimulation of the knee extensors is stopped. Since the knee extensors are stimulated for only a short period, muscle fatigue of the knee extensors seldom occurs. We applied this system to a T8 completely paraplegic patient. Standing-up, standing, walking, and sitting-down motions were all restored by our hybrid system. No electrical stimulation was necessary during standing, and the knee extensors were stimulated during only a small percentage of the 1-gait cycle.

Adult↗

PubMed1996

Lipoprotein lipase activity of post-heparin plasma in Japanese black cattle affected with fat necrosis.

Post-heparin plasma (PHP) lipoprotein lipase (LPL) activity and serum lipoprotein concentration were examined in Japanese Black cows affected with fat necrosis. The PHP-LPL activity in the affected cows was significantly (P < 0.001) higher than in normal animals and tended to reduce 4 weeks after treatment with isoprothiolane. This finding indicates that affected cows have a predisposition to deposit more fat into adipose tissue than normal animals. The serum concentrations of triglyceride in beta-lipoprotein and of cholesterol, phospholipid and total lipid in alpha-lipoprotein were significantly (P < 0.05) lower in the affected cows. Elevated levels of phospholipid and total lipid in alpha-lipoprotein as well as decreased levels of non-esterified fatty acid (NEFA) were observed after medication. It is suggested that isoprothiolane produces an improvement in hepatic lipid metabolism including acceleration of plasma NEFA uptake and alpha-lipoprotein secretion in affected cows.

Animals↗

PubMed1996

Lipogenic and lipolytic activities in isolated adipocytes from cattle with fat necrosis.

The metabolic activity and cellularity of adipocytes isolated from the abdominal adipose tissue of normal heifers and heifers with fat necrosis were compared. The basal rate of U-14C glucose incorporation into total lipids in adipocytes from the periphery of the necrotic mass was higher than that in the colonic mesentery of both the affected and normal heifers. In the affected animals. adipocytes from the mesentery of the spiral colon and adipocytes from the periphery of the necrotic mass failed significantly to increase the incorporation of labelled acetate and glucose, respectively, in response to insulin. In the presence of adrenalin, adipocytes from the colonic mesentery and the periphery of the necrotic mass of the affected heifers released more glycerol than adipocytes from the colonic mesentery of normal animals. In addition, the mean diameters of adipocytes from the colonic mesentery and the periphery of the necrotic mass of the affected heifers were significantly greater than those from the colonic mesentery of normal animals. These results indicate that excessive fattiness in abdominal adipose tissue may predispose cattle to fat necrosis.

Acetates↗

PubMed1996

Anatomic study of the bronchial arteries with special reference to their preservation during the radical dissection of the upper mediastinum lymph nodes.

BACKGROUND: The anatomy of the bronchial arteries was studied, with special reference to their preservation during the radical dissection of the upper mediastinum lymph nodes. METHODS: The bronchial arteries of 71 cadavers were studied macroscopically by use of the surgical field of right thoracotomy. The small branches difficult to identify macroscopically were described by x-ray imaging with digital subtraction angiography. Their anatomic relationship to the adjacent organs was observed microscopically. RESULTS: The bronchial arteries arising from the intercostal arteries (the intercostobronchial arteries) were observed in 66 of 71 cases. By use of the surgical field of right thoracotomy the intercostobronchial arteries were easily found and preserved. All cadavers also had other bronchial arteries arising from the aorta. These were difficult to preserve because of the depth of the surgical field and the location of their course in the dissected area. Bronchial arteries had established connection with each other via the vascular network in the tracheal proper sheath. India ink injected into the intercostobronchial arteries was observed in the tracheal proper sheath and the submucosa of the trachea. CONCLUSIONS: Saving the blood supply to the trachea is possible with careful preservation of the intercostobronchial arteries and the tracheal proper sheath during radical dissection of the upper mediastinum.

Adult↗

PubMed1996

Clinical experience of functional electrical stimulation in complete paraplegia.

Percutaneous intramuscular electrodes and a portable multichannel system were used to restore the function of the paralyzed lower extremities in six patients with complete paraplegia. The total number of inserted electrodes was 168. All of the patients could stand, two could walk in parallel bars, and two could walk with a walker. The rate of breakage of electrodes was only 0.6% in our series. There were 10 (6.0%) superficial infections, and 10 (6.0%) movement of electrodes which required reimplantation. The results suggest that the ultrafine intramuscular electrode is practical for long term use with paraplegic patients. Although the system can be used for paraplegic patients during the activities of daily living, it will be necessary to develop a closed-loop controller to reduce the amount of stimulation to the extensor muscles and extend the endurance of upright activity to reduce fatigue.

Adolescent↗

PubMed1996

Changes in muscle force following therapeutic electrical stimulation in patients with complete paraplegia.

Changes in muscle force following therapeutic electrical stimulation (TES) in 5 patients with complete paraplegia were evaluated by computed tomography, Cybex II, a strain-gauge transducer, and manual muscle testing. The stimulation parameters included a frequency of 20 Hz, a pulse width of 0.2 ms, and an output voltage of -15 V. The cross-sectional areas of muscles, the muscle torques, and the muscle forces increased after TES, though the increased ratio differed in each muscle. The reasons why it differed are as follows: (1) The possibility of peripheral nerve injury; (2) The different patterns of nerve distribution in the muscles; (3) Implantation techniques; and (4) The possibility of breakage, movement, or changes in the impedance of electrodes. This study demonstrates that TES increases muscle force during electrical stimulation in paralyzed muscle, but that an initial TES-induced muscle force greater than a poor-minus level on manual muscle testing is necessary for practical use. TES treatment should be started as soon as possible after the onset of paralysis, in order to maintain muscle quality.

Adult↗

PubMed1996

Endothelium-dependent vasodilator effect of extract prepared from the roots of Paeonia lactiflora on isolated rat aorta.

Paeoniae Radix (the roots of Paeonia lactiflora Pallas) is a crude drug that is used in Asia and Europe to improve blood flow. We studied its vasodilator effect and mechanisms of action in vitro. The extract from Paeoniae Radix (PRE) relaxed prostaglandin F2a-precontracted aortic ring preparations of isolated rat aorta that contained endothelium. Relaxation by PRE did not occur in specimens without endothelium, and was inhibited by pretreatment with 10(-4) M NG-nitro-1-arginine methyl ester. Paeoniflorin and paeonol, the main active components of Paeoniae Radix, lacked a vasodilator effect. The effect of the component gallotannin was examined after treating PRE with tannase, but the product lacked a vasodilator effect. Pentagalloylglucose, hexagalloylglucose, heptagalloylglucose, and octagalloylglucose were extracted from PRE; they relaxed aortic rings with endothelium, but failed to relax aortic rings without endothelium. We conclude that PRE exhibits an endothelium-dependent vasodilator effect on isolated rat aorta. The active component is gallotannin.

Acetophenones↗

PubMed1996

An early phase II study of etoposide (VP-16) in advanced gastric cancer.

An early phase II study was conducted to evaluate the anti-tumor effects and toxicity of etoposide in patients with unresectable or relapsed advanced gastric cancer. From April 1991 to December 1992, 13 patients were enrolled into this study; one was subsequently considered ineligible. Before enrollment, all the patients had been treated with chemotherapy which did not include etoposide. Etoposide (100 mg/m2/day) was administered as an intravenous infusion over 120 min for five consecutive days and was repeated every four weeks. Seven patients received one course of this therapy and the remaining five received two. No patient showed a complete or a partial response. No change and progressive disease were observed in three and nine patients, respectively. The clinical toxicities (grade 3-4; WHO) of leukocytopenia, anemia and alopecia occurred in 50, 42, and 42% of the patients, respectively. We conclude that this dose of etoposide administered according to the present schedule is ineffective in previously treated patients with advanced gastric cancer.

Adenocarcinoma↗

PubMed1996

Alterations in spectral characteristics of heart rate variability as a correlate of cardiac autonomic dysfunction after esophagectomy or pulmonary resection.

BACKGROUND: Both esophagectomy and pulmonary resection are associated with postoperative cardiac complications, partly because of autonomic perturbations involving the heart. This study was undertaken to determine whether heart rate variability (HRV), employed as an index of cardiac autonomic function, changes in patients undergoing esophagectomy or pulmonary resection. METHODS: Electrocardiographic RR intervals were measured in 20 esophagectomized patients, 10 undergoing right and 10 undergoing left pulmonary resection on the preoperative day as baseline data and on postoperative days 1, 3, 5, 7, 14, and 30. Instantaneous heart rate was calculated every 250 ms from 416-s data of RR intervals. Power spectra of HRV for 128 s were computed using a fast Fourier transform and normalized by squared mean heart rate. The average ten sets of normalized HRV power were obtained by integrating the following power spectral bands: the low-, (0.06-0.10 Hz), high- (0.15-0.40 Hz), and total-frequency regions (0.01-0.40 Hz). RESULTS: In the esophagectomy group, mean low-, high-, and total-frequency HRV power decreased after surgery to 17%, 6%, and 15% of their preoperative values, respectively, and these indexes remained suppressed for up to 30 days. After right pulmonary resection, low- and total-frequency HRV power decreased through 30 and 7 postoperative days, respectively. In the left pulmonary resection group, HRV remained unchanged. In the esophagectomy group, mean (+/- SEM) heart rate increased from 78 (+/- 3) bpm to more than 90 bpm throughout the study, and body temperature from 36.5 (+/- 0.1) degrees C to more than 37.0 degrees C through 14 postoperative days. Heart rate and body temperature remained increased for 3 days after pulmonary surgery. Mean arterial pressure remained unchanged in the three surgical groups. CONCLUSIONS: Reductions indicate HRV after esophagectomy or right pulmonary resection indicate a substantial and prolonged surgical injury to the autonomic nervous control of pulse rate.

Aged↗

PubMed1996

A numerical model for the analysis and evaluation of global 137Cs fallout.

Fallout 137Cs from atmospheric nuclear detonation tests has been monitored worldwide since the late 1950's. The deviation and the correlation among these monitoring data were analyzed, and their surface deposition characteristics were estimated by the compartment model developed in this research. In the analysis, the scale of space (i.e., size of each compartment) and the degree of detail (i.e., number of compartments) were statistically determined using the global distribution data of 137Cs. The mathematical model was evaluated by comparing the numerically stimulated results with the fallout monitoring data including the 137Cs concentration in sea water. The major findings obtained in this research include that the deposition pattern of 137Cs is dependent on the latitude zone but not on the longitude, the mathematical model is promising for evaluating the dynamic performance of 137Cs in global atmospheric environment and its surface deposition, 137Cs is accumulated more in both the surface and deep ocean water of the North Pacific Ocean and the North Atlantic Ocean than that of other oceans, the 137Cs inventory is decreasing after the peak time in 1965, and the 137Cs inventory in the deep ocean water is decreasing more slowly than that in the surface ocean water.

Cesium Radioisotopes↗