Diffusion tensor imaging of the brain: effects of distortion correction with correspondence to numbers of encoding directions

Purpose  The aim of the study was to estimate the effect of distortion correction with correspondence to numbers of encoding directions to acquire diffusion tensor imaging (DTI) of improved quality. Materials and methods  Ten volunteers underwent DTI of the head using echo planar imaging with 6, 13, 27, and 55 encoding directions. Fractional anisotropy (FA) maps and apparent diffusion coefficient (ADC) maps were created before and after distortion correction. Regions of interest were placed in the corpus callosum on each map, and standard deviations of FA and ADC were calculated. FA maps were also evaluated visually by experienced neuroradiologists. Results  Dispersion of standard deviations tended to be reduced after distortion correction, with significant differences found in FA maps with 6 encoding directions, ADC maps with 6 directions, and ADC maps with 13 directions (P < 0.001, P < 0.005, and P < 0.05, respectively). Visual image quality was improved after distortion correction (P < 0.01 for all of the visual comparisons). Conclusion  Distortion correction is effective in providing DTI of enhanced quality, notwithstanding the number of encoding directions. This article was presented at a Japan Radiological Society meeting in 2002     

Propofol-induced anesthesia in mice is mediated by gamma-aminobutyric acid-A and excitatory amino acid receptors

To elucidate the role of gamma-aminobutyric acid (GABA)(A) receptor complex and excitatory amino acid receptors (N-methyl-D-aspartate [NMDA] and non-NMDA receptors) in propofol-induced anesthesia, we examined behaviorally the effects of GABAergic and glutamatergic drugs on propofol anesthesia in mice. All drugs were administered intraperitoneally. General anesthetic potencies were evaluated using a righting reflex assay. The GABA(A) receptor agonist muscimol potentiated propofol (140 mg/kg; 50% effective dose for loss of righting reflex) induced anesthesia. Similarly, the benzodiazepine receptor agonist diazepam and the NMDA receptor antagonist MK-801 augmented propofol anesthesia, but the non-NMDA receptor antagonist CNQX did not. In contrast, the GABA(A) receptor antagonist bicuculline antagonized propofol (200 mg/kg; 95% effective dose for loss of righting reflex) induced anesthesia. However, neither the benzodiazepine receptor antagonist flumazenil, the GABA synthesis inhibitor L-allylglycine, nor the NMDA receptor agonist NMDA reversed propofol anesthesia. Conversely, the non-NMDA receptor agonist kainate enhanced propofol anesthesia. These results suggest that propofol-induced anesthesia is mediated, at least in part, by both GABA(A) and excitatory amino acid receptors. IMPLICATIONS: We examined behaviorally the effects of GABAergic and glutamatergic drugs on propofol-induced anesthesia in mice. The results suggest that propofol anesthesia is mediated, at least in part, by both GABA(A) and excitatory amino acid receptors.     

Bcl-2 protects tubular epithelial cells from ischemia reperfusion injury by inhibiting apoptosis

Ischemia followed by reperfusion leads to severe organ injury and dysfunction. Inflammation is considered to be the most important cause of graft dysfunction in kidney transplantation subjected to ischemia. The mechanism that triggers inflammation and renal injury after ischemia remains to be elucidated; however, cellular stress may induce apoptosis during the first hours and days after transplantation, which might play a crucial role in early graft dysfunction. Bcl-2 is known to inhibit apoptosis induced by the etiological factors promoting ischemia and reperfusion injury. Accordingly, we hypothesized that an augmentation of the antiapoptotic factor Bcl-2 may thus protect tubular epithelial cells by inhibiting apoptosis, thereby ameliorating the subsequent tubulointerstitial injury. We examined the effects of Bcl-2 overexpression on ischemia-reperfusion (I/R) injury using Bcl-2 transgenic mice (Bcl-2 TG) and their wild-type littermates (WT). To investigate the effects of I/R injury, the left renal artery and vein were clamped for 45 min, followed by reperfusion for 0-96 h. Bcl-2 TG exhibited decreased active caspase protein in the tubular cells, which led to a reduction in TUNEL-positive apoptotic cells. Consequently, interstitial fibrosis and phenotypic changes were ameliorated in Bcl-2 TG. In conclusion, Bcl-2 augmentation protected renal tubular epithelial cells from I/R, and subsequent interstitial injury by inhibiting tubular apoptosis.     

Kinematic analysis of mobile-bearing total knee arthroplasty using a 6-DOF knee simulator

Background  The purpose of this study was to investigate the kinematics of the polyethylene insert in two designs of mobilebearing total knee arthroplasty, using a six-degrees-of-freedom knee simulator. It was consequently not clear whether the motion of the polyethylene bearing in mobile-bearing total knee arthroplasty could be demonstrated during the gait cycle or more rapid movement. Methods  A mobile-bearing knee (Zimmer) and a low contact stress rotating-platform design (Depuy) were mounted on a simulator which was regulated by the kinematic data of gait. The simulating test was conducted under a static condition as well as under dynamic conditions of 0.5 Hz and 1.0 Hz. We recorded the motions of the implants with two charge-coupled device (CCD) cameras, and the positions of the insert were calculated. Results  In spite of the same relative motion between the femoral component and the tibial tray, the polyethylene insert showed unique relative motion according to the given condition. The motion of the insert during the dynamic conditions was considerably decreased in comparison to the static condition in both mobile-bearing designs. In addition, the insert showed a smaller amplitude and frequency of rotations under increasing speed in the low contact stress rotating-platform design. The low contact stress rotating-platform design showed a larger amplitude and frequency of rotations than the mobilebearing knee. Conclusions  Despite the mobility of the insert in the mobilebearing total knee arthroplasty, the motion of the insert was decreased during dynamic conditions because of the disruption of full contact between the femoral component and the polyethylene insert. Differences in the rotation between the mobile-bearing knee and the low contact stress rotatingplatform design were due to the fixed axis of the internalexternal rotation in the low contact stress rotating-platform design. The theoretical advantages for the mobile-bearing design over the fixed-bearing design were not demonstrated in this study.     

The Number of Metastatic Lymph Nodes is a Significant Risk Factor for Bone Metastasis and Poor Outcome After Surgery for Linitis Plastica-type Gastric Carcinoma

BACKGROUND: Linitis plastica-type gastric carcinoma remains a disease with poor prognosis despite an aggressive surgical approach. Although a prominent pattern of disease failure is peritoneal carcinomatosis, some patients experience rapid disease progression without signs of the peritoneal disease. METHODS: Clinicopathologic data from 178 patients with linitis plastica-type gastric cancer operated on between 1991 and 2000 were analyzed. Survival stratified by curability of surgery, pN stage, and patterns of failure were evaluated by using the Kaplan-Meier method, and chi(2) test was used to evaluate correlation between the number of metastatic lymph nodes in terms of pN categories and the incidence of various patterns of metastasis and recurrence. Cox regression hazard model was used to identify independent prognostic factors. RESULTS: R0 resection was performed only among 82 patients (46% of those who underwent laparotomy). Node metastasis was frequent with only 22 patients classified as pN0. Peritoneal carcinomatosis was observed in 131 patients and was the commonest pattern of recurrence. Bone metastasis, found in 13 patients, was associated with poor outcome, and its incidence was significantly correlated with the number of metastatic nodes. pT4 status and pN3 status were identified as significant independent prognostic determinants. CONCLUSION: Treatment strategy for the linitis plastica should in general combine surgery with aggressive treatment directed toward peritoneal disease. However, patients with >16 metastatic nodes more often are associated with bone metastasis than those with modest nodal involvement and suffer from poor prognosis.     

Optic radiation tractography integrated into simulated treatment planning for Gamma Knife surgery

OBJECT: No definitive method of preventing visual field deficits after stereotactic radiosurgery for lesions near the optic radiation (OR) has been available so far. The authors report the results of integrating OR tractography based on diffusion tensor (DT) magnetic resonance imaging into simulated treatment planning for Gamma Knife surgery (GKS). METHODS: Data from imaging studies performed in 10 patients who underwent GKS for treatment of arteriovenous malformations (AVMs) located adjacent to the OR were used for the simulated treatment planning. Diffusion tensor images performed without the patient's head being secured by a stereotactic frame were used for DT tractography, and the OR was visualized by means of software developed by the authors. Data from stereotactic 3D imaging studies performed after frame fixation were coregistered with the data from DT tractography. The combined images were transferred to a GKS treatment-planning workstation. Delivered doses and distances between the treated lesions and the OR were analyzed and correlated with posttreatment neurological changes. RESULTS: In patients presenting with migraine with visual aura or occipital lobe epilepsy, the OR was located within 11 mm from AVMs. In a patient who developed new quadrantanopia after GKS, the OR had received 32 Gy. A maximum dose to the OR of less than 12 Gy did not cause new visual field deficits. A maximum dose to the OR of 8 Gy or more was significantly related to neurological change (p < 0.05), including visual field deficits and development or improvement of migraine. CONCLUSIONS: Integration of OR tractography into GKS represents a promising tool for preventing GKS-induced visual disturbances and headaches. Single-session irradiation at a dose of 8 Gy or more was associated with neurological change.     

Lactate dehydrogenase is a prognostic indicator for prostate cancer patients with bone metastasis

We analyzed clinical data to identify prognostic indicators in prostate cancer patients with bone metastasis. The subjects were 60 patients with bone metastasis out of 165 patients diagnosed with prostate cancer at our clinic over 6 years from January 1998 to December 2003. The age at the initial diagnosis was 61 to 91 (mean: 73.7 +/- 7.5) years old. The following items were considered to be possible prognostic indicators: T (type) classification, N (node) classification, Gleason score, prostate specific antigen (PSA) value before therapy, disease grade, alkaline phosphatase (ALP), lactate dehydrogenase (LDH), serum calcium (Ca), hemoglobin (Hgb), and platelet count (Plt). The 5-year overall survival rate was 45.7% in the 60 patients. Univariate analysis showed statistically significant differences in N (1), Gleason score 7 + 8/Gleason score 9 + 10, and LDH level (p = 0.0053, 0.0261, and 0.0049, respectively). Multivariate Cox proportional hazard analysis of these three items showed a statistically significant difference in LDH level and Gleason score 9 +/- 10 (p = 0.0167 and 0.0371). LDH was suggested to be an excellent prognostic indicator, because of its objectivity and convenience of measurement, in prostate cancer patients with bone metastasis.     

Left circumflex coronary aneurysm with separated left main trunk

We report a left circumflex coronary aneurysm associated with separated left main coronary trunks (LMT). A 66-year-old man was admitted to our hospital for further examination of dyspnea on effort. He has been performed maintenance hemodialysis since 1999 for chronic renal failure. Coronary angiography and multislice spiral computed tomography (CT) revealed an unusual coronary anatomic variance in which separate origins of the left anterior descending (LAD) and left circumflex (LCx) coronary arteries arose from the left coronary aortic sinus. Furthermore, these images of the LCx revealed an aneurysm 2 cm in diameter and 99% stenosis at the proximal of side of the aneurysm. Under cardioplegic arrest, the aneurysm was ligated and coronary artery bypass grafting (left thoracic artery to posterolateral branch) was performed. The patient was discharged at the 20th postoperative day without any complication.     

Erythropoietin protects the kidneys against ischemia reperfusion injury by activating hypoxia inducible factor-1alpha

BACKGROUND: Ischemia/reperfusion (I/R) injury is closely associated with tissue damage in various organs, as well as in kidney transplants. Erythropoietin (EPO) has been shown to have a cytoprotective effect against hypoxia. We examined the effect of EPO against renal I/R injury and the underlying mechanism. METHODS: Human umbilical vein endothelial cells and human renal proximal tubular epithelial cells were cultured under hypoxic conditions with various EPO concentrations at 37 degrees C and examined the mechanism of cell proliferation by EPO. Moreover, to demonstrate the renoprotective effect in vivo, we treated Sprague-Dawley rats with 100 IU/kg EPO every 2 days for 2 weeks (a total of 6 doses). One day after the last injection, the operations to produce renal I/R injury (bilateral renal occlusion for 60 min) were done, and rats were killed at the end of the reperfusion period (24 hr and 72 hr after reperfusion began). RESULTS: First, we demonstrated in vitro that EPO increased hypoxia inducible factor-1alpha (HIF-1alpha) expression and stimulated proliferation of both cells under hypoxic conditions. Next, we demonstrated in vivo that EPO treatment increased the number of HIF-1alpha-positive cells, and markedly induced the expression of vascular endothelial growth factor messenger RNA. Using pimonidazole, a molecular probe that detects hypoxia, we found that EPO markedly attenuated tubular hypoxia, and reduced the number of terminal transferase dUTP nick end labeling-positive apoptotic cells and alpha-smooth muscle actin-positive interstitial cells. CONCLUSIONS: We suggested a novel HIF-1alpha induction pathway by EPO under hypoxic conditions. Thus, EPO may protect the kidneys against ischemia reperfusion injury by activating HIF-1alpha.     

Prophylaxis of nausea and vomiting after laparoscopic cholecystectomy with ramosetron: randomised controlled trial.

OBJECTIVE: To evaluate the efficacy and safety of ramosetron (a 5-hydroxytryptamine type 3 receptor antagonist) for the prevention of nausea and vomiting after laparoscopic cholecystectomy. DESIGN: Prospective, randomised, double-blind, placebo-controlled study. SETTING: University and university-affiliated hospitals, Japan. SUBJECTS: 100 patients, 65 women and 35 men, who had laparoscopic cholecystectomy. INTERVENTIONS: Patients were given either placebo or ramosetron at 3 different doses (0.15 mg, 0.3 mg, 0.6 mg) intravenously at the completion of operation. The general anaesthetic technique and postoperative analgesia were standard. MAIN OUTCOME MEASURES: Vomiting and safety were assessed for 0 to 24 hours and 24 to 48 hours after anaesthesia. RESULTS: The number of patients who had a complete response (no nausea, no retching, no vomiting) during 0 to 24 hours after anaesthesia was 15/25 with placebo, 17/25 with ramosetron 0.15 mg, 23/25 with ramosetron 0.3 mg, and 23/25 with ramosetron 0.6 mg; The corresponding numbers from 24 to 48 hours were 16, 17, 23, and 23. No serious adverse events were observed in any of the groups. CONCLUSIONS: Ramosetron 0.3 mg was the minimum effective dose for preventing postoperative nausea and vomiting during 0 to 48 hours after anaesthesia in patients undergoing laparoscopic cholecystectomy.