Biomedical subjects

Hiroshi Nishimura

Publications and source records attributed to Hiroshi Nishimura.

25 records · Page 2Linked to original sources

PubMed2002

MRI quantification of muscle activity after volitional exercise and neuromuscular electrical stimulation.

OBJECTIVE: The efficacy, and even the depth, of muscle stimulation during surface electrode neuromuscular electrical stimulation (NMES) is a matter of debate. This study addresses these issues by assessing the utility of a magnetic resonance imaging (MRI) technique in localizing and quantitating changes in the nature of MRI signals in the quadriceps muscle after volitional exercise and NMES. DESIGN: Volitional isometric and NMES-evoked quadriceps muscle activity was evaluated in two controlled trials. In the first, isometric quadriceps strength was determined during NMES and maximal volitional isometric exercise in six healthy men. In the second, changes in the ratio of MRI T2 signal intensities before and after volitional isometric exercise and NMES were used to quantitate MRI signal changes associated with muscle activation in 12 additional healthy men. RESULTS: MRI clearly detected quadriceps muscle tissue activation after both volitional and stimulated contractions, even though the NMES knee extension torque was only 23.5% that of maximal volitional isometric exercise. In particular, the T2 intensity ratios increased 26.5% +/- 17.3% (mean +/- standard deviation) after volitional exercise and 12.9% +/- 12.8% after NMES. This pattern of volitional isometric exercise, producing larger T2 intensity ratio values than NMES, was present in both deep and superficial layers and throughout the quadriceps muscle. CONCLUSIONS: Although volitional muscle contractions were several times stronger than those induced by NMES in this study, our findings support the idea that MRI can provide a noninvasive way to quantitate and localize volitional and electrically stimulated muscle activation.

Adult↗

PubMed2002

A diminished intrapartum amniotic fluid index is a predictive marker of possible adverse neonatal outcome when associated with prolonged labor.

OBJECTIVE: To determine whether a diminished intrapartum amniotic fluid volume represents a risk of adverse neonatal outcome when it occurs in conjunction with prolonged labor. METHODS: The intrapartum amniotic fluid index (iAFI) was measured in 242 parturients over 35 weeks of gestation during 1st-stage labor, and the umbilical artery blood gas was analyzed at delivery. The subjects were divided into group A (n = 99), having a diminished amniotic fluid volume (iAFI < or = 8.0 cm) and group B (n = 143), having a normal amniotic fluid volume (iAFI 8.1-20.0 cm), and selected antenatal, delivery, and neonatal variables were compared. In addition, the two groups were subdivided according to the duration of labor. Statistical analysis was performed using independent Student's t test, Mann-Whitney U test, chi-square analysis, and Fisher's exact test where appropriate. p < 0.05 was considered significant. RESULTS: The patient characteristics and pregnancy outcomes were similar in groups A and B, as were the incidences of an umbilical artery blood pH <7.20 and/or an Apgar score <7 (group A 9.5%, group B 10.1%). In group A, however, the incidence of an adverse neonatal outcome was 23.5% in cases in whom the duration of labor was longer than 8 h which was significantly higher than in cases in whom the duration of labor was 8 h or less (2.8%; p < 0.01). In group B, the incidence of an adverse neonatal outcome was similar in the two subgroups. CONCLUSIONS: The risk of an adverse neonatal outcome is higher in patients with diminished amniotic fluid volume if labor is prolonged. Consequently, determination of the iAFI could be a useful admission test.

Adult↗

PubMed2002

Evolution of virtual CT laparoscopy for preoperative imaging in laparoscopic cholecystectomy.

The purpose of this study was to determine the feasibility of virtual endoscopy, named as "virtual CT laparoscopy", in the hepatobiliary system prior to laparoscopic cholecystectomy. We applied this technique to 28 patients suspected of having biliary disease. These images were compared and analyzed qualitatively based on visualization of the structures critical to operative cholangiography and surgical findings. Twenty-four patients, who underwent laparoscopic cholecystectomy, were evaluated as follows: the common bile duct and the hepatic duct were adequately visualized in 23 (96%) of the 24 patients, the cystic duct in 21 (88%), the gallbladder opacification in 20 (83%), the liver inferior surface in 20 (83%). Four patients had anatomic variations detected virtual CT laparoscopy and were proven by operative cholangiography and surgical findings. We emphasize that our new technique may contribute to the laparoscopy during surgery as the aid of understanding of anatomical structures in these organs.

Adult↗

PubMed2002

[Apparent size and judgment-order effect: a magnitude estimation study of the Delboeuf illusion].

Apparent sizes of circles in the Delboeuf figure were measured by magnitude estimation without modulus. The purpose was to investigate the Delboeuf illusion and the effect of judgment order on perceived size. Contrary to the conventional Delboeuf illusion, overestimation effects appeared for outer circles at small diameter differences. The illusory magnitude depended on the diameter ratio and diameter difference of the constituent circles. The maximum magnitude of the illusion did not always appear at the diameter ratio, 0.67 (as found before by the method of limits). The circle judged first had an assimilative effect on the apparent size of the subsequently judged circle. The time-order dependency of assimilation was more pronounced for the inner than for the outer circle. The judgment-order effect may be accounted for by the attention mechanism.

Attention↗

PubMedDate not supplied

Development of a rhenium-186-labeled MAG3-conjugated bisphosphonate for the palliation of metastatic bone pain based on the concept of bifunctional radiopharmaceuticals.

Rhenium-186-1-hydroxyethylidene-1,1-diphosphonate (186Re-HEDP) has been used for the palliation of metastatic bone pain. Delayed blood clearance and high gastric uptake of radioactivity have been observed upon injection, due to the instability of (186)Re-HEDP in vivo. In this study, on the basis of the concept of bifunctional radiopharmaceuticals, we designed a stable 186Re-mercaptoacetylglycylglycylglycine (MAG3) complex-conjugated bisphosphonate, [[[[(4-hydroxy-4,4-diphosphonobutyl)carbamoylmethyl]carbamoylmethyl]carbamoylmethyl]carbamoylmethanethiolate]oxorhenium(V) (186Re-MAG3-HBP). As a precursor, [1-hydroxy-1-phosphono-4-[2-[2-[2-(2-tritylmercaptoacetylamino)acetylamino]acetylamino]acetylamino]butyl]phosphonic acid (Tr-MAG3-HBP) was synthesized by the conjugation of N-[(tritylmercapto)acetyl]glycylglycylglycine (Tr-MAG3) with the bisphosphonate analogue. After deprotection of the trityl group of Tr-MAG3-HBP, 186Re-labeling was performed by reacting 186ReO4- with SnCl2 in citrate buffer. After purification by HPLC, 186Re-MAG3-HBP showed a radiochemical purity of over 95%. To compare the stability of 186Re-MAG3-HBP and 186Re-HEDP, these (186)Re complexes were incubated in phosphate buffer. No measurable decomposition of 186Re-MAG3-HBP occurred over a 24-h period, while only approximately 30% of 186Re-HEDP remained intact 24 h postincubation. In biodistribution experiments, the radioactivity level of 186Re-MAG3-HBP in bone was significantly higher than that of (186)Re-HEDP. Blood clearance of 186Re-MAG3-HBP was faster than that of 186Re-HEDP. In addition, the gastric accumulation of 186Re-MAG3-HBP radioactivity was lower than that of 186Re-HEDP. In conclusion, 186Re-MAG3-HBP is expected to be a useful radiopharmaceutical for the palliation of metastatic bone pain.

Bone Neoplasms↗

PubMedDate not supplied

Assessment of pancreatic CT enhancement using a high concentration of contrast material.

OBJECTIVE: To evaluate the usefulness of pancreatic enhancement using a high concentration of contrast material in CT. METHODS: We performed abdominal CT on 125 patients after dividing them at random into five groups with two different concentrations, two different injection rates and three different injection doses: group A: 100 ml, 300 mgI/mL, 3 mL/sec; group B: 2 mL/kg, 300 mgI/mL, 3 mL/sec; group C: 1.5 mL/kg, 370 mgI/mL, 3 mL/sec; group D: 2 mL/kg, 300 mgI/mL, 5 mL/ sec; and group E: 1.5 mL/kg, 370 mgI/mL, 5 mL/sec. Among these five groups, the two groups given a concentration of 370 mgI/mL received a dose of 1.5 mL/body weight. RESULTS: The peak enhancement value of the pancreas was significantly greater in group E than in groups A and B. However, no statistically significant differences were found among the other groups. CONCLUSION: The fast injection rate using the high concentration of contrast medium provided greater enhancement of the pancreas than the slow injection rate using the routine concentration of contrast medium, and pancreatic CT enhancement depended more on the dose of iodine per second than on that of total iodine.

Adult↗

PubMedDate not supplied

Blood brain-barrier disruption of nonionic iodinated contrast medium following coil embolization of a ruptured intracerebral aneurysm.

Few reports of temporary disruption of the blood-brain barrier (BBB) following neurointerventional procedures, presumably caused by nonionic radiographic contrast medium (CM), exist in the literature. We described such a case in a 72-year-old man presenting with acute subarachnoid hemorrhage, who underwent coil embolization of a ruptured anterior communicating artery complex aneurysm. At the time of his follow-up CT examination, a large amount of iodine was found in the cerebrospinal fluid (CSF). Because of this experience, the iodine concentration in the CSF of five other patients who also underwent an intracranial endovascular procedure was measured. It was concluded that this increased iodine might have been caused by temporary leakage or breakdown of the BBB. Even if the total amount of CM may not be excessive, the disproportionately high concentration injected into a single vascular territory may pose a unique set of variables increasing the risk of BBB disruption.

Aged↗