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Biomedical subjects

M Reiser

Publications and source records attributed to M Reiser.

At least 91 records · Page 5Linked to original sources
PubMed2001

Correlation of coronary calcification and angiographically documented stenoses in patients with suspected coronary artery disease: results of 1,764 patients.

OBJECTIVES: This study correlated the electron beam computed tomographic (EBCT) calcium scores with the results of coronary angiography in symptomatic patients in order to assess its value to predict or exclude significant coronary artery disease (CAD). BACKGROUND: Electron beam computed tomography is a sensitive method to detect coronary calcium. However, it is unclear whether it may play a role as a filter before invasive procedures in symptomatic patients. METHODS: A total of 1,764 patients (1,225 men and 539 women) with suspected CAD from a single center were included in our study. All patients underwent calcium screening with EBCT (C150XP Imatron) and conventional coronary angiography. RESULTS: Fifty-six percent of men and 47% of women revealed significant coronary stenoses (> or =50%). Total exclusion of coronary calcium (14% of the study group) was associated with an extremely low probability of stenosis (<1%). With calcium scores > or =20th, > or =100th or > or =75th percentile of age groups, the sensitivity to detect stenoses decreased to 97%, 93% and 81%, respectively, in men and to 98%, 82% and 76%, respectively, in women. At the same time, the specificity increased up to 77% in men and women. There was a significant difference in coronary calcium between men and women in all age groups; however, receiver-operating characteristic curves indicated that the test can be performed with equal accuracy in all of these subgroups. CONCLUSIONS: Calcium screening with EBCT is a highly sensitive and moderately specific test to predict stenotic disease. Exclusion of coronary calcium defines a substantial subgroup of patients, albeit symptomatic, with a very low probability of significant stenoses.

Adult↗
PubMed2001

Three-dimensional analysis of shoulder girdle and supraspinatus motion patterns in patients with impingement syndrome.

Alterations of the shoulder girdle motion have been suggested to be associated with shoulder disorders. The objective of this study was to perform a three-dimensional (3D) motion analysis of the supraspinatus muscle and shoulder girdle in patients with different stages of impingement syndrome. 20 patients with unilateral impingement and 14 normal controls were investigated at 30 degrees, 90 degrees, and 120 degrees of abduction with and without abducting muscle activity. The spatial relationship between the shoulder girdle elements and the supraspinatus was quantified from open MRI data. No significant alterations in glenoid rotation were observed between the patients and asymptomatic volunteers. However, while in the healthy volunteers the values showed a normal distribution (28.5+/-3.6 degrees at 90 degrees abduction with muscle activity), the patients (30.5 degrees+/-9.7 degrees) contained a subset of five individuals with an obvious increase in glenoid rotation angle (>40 degrees) compared with controls (>2.5 standard deviations higher than the mean) and with the healthy contralateral side. These five patients also displayed alterations in the scapulo-humeral rhythm and supraspinatus motion, but not in clavicular position. The study shows that only a specific subset of patients with impingement syndrome demonstrates complex changes in shoulder girdle and supraspinatus motion patterns, suggesting that this subset may benefit from an alternative type of treatment.

Adult↗
PubMed2001

Parental socialization of children's dysregulated expression of emotion and externalizing problems.

The relations of parents' warmth, emotional expressivity, and discussion of emotion to 2nd-5th graders' regulation of emotional expressivity, externalizing problem behaviors, and expressivity were examined. Parents' and children's facial expressions to evocative slides were observed, as was parents' discussion of the slides, and parents and teachers provided information on children's regulation of expressivity and problem behavior. Analyses supported the hypothesis that the effect of parental variables on children's problem behavior was at least partly indirect through their children's regulation of emotion. Children's low negative (versus positive) facial expressivity to negative slides was associated with problem behavior for boys. A reversed model did not support the possibility that children's functioning had causal effects on parenting. The findings suggest that parents' emotion-related behaviors are linked to children's regulation of expressivity and externalizing behaviors.

Affect↗
PubMed2001

Interindividual variability and correlation among morphological parameters of knee joint cartilage plates: analysis with three-dimensional MR imaging.

OBJECTIVE: To determine the range and variability of the cartilage volume, thickness, and articular surface areas in the knee joints of healthy male subjects, the association of these parameters within and between the knee joint cartilage plates, and their correlation with anthropometric variables. METHOD: The right knees of 27 individuals (age 23 to 64 years) without cartilage damage were examined. Sagittal magnetic resonance imaging was with a fat-suppressed gradient echo sequence (resolution 2 x 0.31 x 0.31 mm(3)), quantitative parameters being computed for all cartilage plates. RESULTS: The total knee joint cartilage volume ranged from 16.6 to 31.4 ml, the size of the articular surfaces from 102 to 163 cm(2), and the mean cartilage thickness from 1.57 to 2.43 mm. The mean and maximal cartilage thickness were highest in the patella (2.76 and 5.72 mm). There was a significant correlation of the cartilage volume with the mean thickness (R=0.80) and with the joint surface areas (R=0.56), but not between the thickness and surface area (R=0.37). The association among the patella, tibia, and femur was 0.16 to 0.72 for volumes, 0.08 to 0.78 for thickness, and 0.24 to 0.62 for surfaces. The knee joint cartilage volume and the surface areas were significantly associated with the body height (R=0.51 and 0.57), but not the cartilage thickness (R=0.22). CONCLUSION: There is a surprisingly high variability of the quantitative distribution of cartilage within the knee joint, with only moderate correlations between knee joint cartilage plates, and this variability cannot be adequately predicted based on anthropometric variables.

Adult↗
PubMed2001

Diffusion-weighted magnetic resonance imaging of spinal bone marrow.

Diffusion-weighted (DW) imaging is an alternative source of image contrast. DW imaging enables to measure the random motion of free water protons on a molecular basis by using different imaging sequences including steady-state free precession imaging, navigated spin-echo DW imaging, and single-shot echo planar imaging. Analysis of intravoxel incoherent motion of water protons is a promising tool that has shown to be of value in the differential diagnosis between benign and malignant spontaneous vertebral fractures. Acute benign osteoporotic fractures show hypo- or isointense signal on DW sequences that reflects persistent free water proton mobility. With increasing diffusion strength a substantial signal loss is found. Metastatic fractures show hyperintensity compared with normal surrounding bone marrow probably due to altered water proton mobility within neoplasm. The ability of the different methods for DW imaging to differentiate other bone marrow alterations needs to be investigated in further studies.

Bone Marrow↗
PubMed2001

[Evaluation of an electromagnetic virtual target system (CT-guide) for CT-guided interventions].

PURPOSE: Evaluation of the accuracy of a new electromagnetic target system for interventional CT-guided procedures with virtual navigation in a previously acquired helical CT. MATERIAL AND METHODS: The new target system CT-Guide 1010 (Ultraguide, Tirat Hacarmel, Israel) for CT-guided interventions was adapted to the video signal of the Somatom Plus 4 and Volume Zoom (Siemens, Erlangen, Germany). A helical CT-dataset including skin-based sensor cubes was transferred to the integrated navigation system inside the scanner room. 50 image-guided interventions and biopsies were performed outside the gantry using virtual navigation to reach the lesion. The accuracy of the procedures was evaluated using documentation of the needle tip with CT-fluoroscopy, results of histology, and follow-up. RESULTS: The deviation between planned and documented needle tip was 2.2 +/- 2.1 mm in 50 procedures. Time between the end of planning-CT and needle positioning using the system was 13 minutes. There were no complications due to the use of the system. CONCLUSION: The CT-Guide allows for virtual real-time navigation with high accuracy. Advantages are the free needle angulation without gantry tilt, use of optimal CT perfusion phase for virtual navigation, and reduction of radiation exposure to the patient and interventionalist.

Adult↗
PubMed2001

Lack of neuronal NOS has consequences for the expression of POMC and POMC-derived peptides in the mouse pituitary.

The relevance of NO in neuroendocrine signalling has been investigated by analysis of cellular expression of pro-opiomelanocortin (POMC) and the POMC-derived peptides beta-endorphin, alpha-melanocyte stimulating hormone and adrenocorticotropin. Expression patterns were studied in the pituitary gland of 150-day old wild-type and neuronal-NOS (nNOS) knock-out mice by using immunohistochemistry, in situ hybridization and Northern blot analysis. Remaining NO-generating capacities in the knock-out mice were demonstrated by immunohistochemical localization of inducible, endothelial and neuronal NOS isoforms. Quantitative analysis revealed that cellular expression of POMC mRNA was drastically reduced in the pituitary of knock-out mice in comparison to controls. In situ hybridization studies demonstrated that this reduction was most pronounced in the intermediate lobe, while the anterior lobe was much less affected. Immunostaining for the proteolytic fragments of POMC was significantly reduced in the intermediate lobe cells of knock-out mice. A moderate reduction of immunostaining for these peptides was also observed in adenopituitary cells of nNOS knock-out mice. Our data demonstrate that the lack of nNOS substantially affects cellular levels of pituitary opioid peptides, which may have consequences for the response of these animals to stress and pain.

Adrenocorticotropic Hormone↗
PubMed2001

Cervical spine: postmortem assessment of accident injuries--comparison of radiographic, MR imaging, anatomic, and pathologic findings.

PURPOSE: To assess the ability of postmortem radiography and magnetic resonance (MR) imaging to depict occult cervical spine injuries as compared with anatomic and pathologic findings. MATERIALS AND METHODS: The cervical spines of 10 adult accident victims underwent radiography and MR imaging, with T1-weighted, fast spin-echo T2-weighted, and four gradient-echo pulse sequences. The frozen specimens were cut into 3-mm-thick slices (sagittal plane) and photographed, and microfocus radiographs were obtained. Imaging findings were compared with the anatomic and pathologic findings. RESULTS: Eight of the 10 specimens had 28 posttraumatic lesions: three fractures (two missed at the initial MR imaging reading), 10 facet joint capsule lesions with bleeding, five soft-tissue and ligament lesions, eight disk lesions, and two spinal cord lesions. Radiography depicted one lesion (4%). Two partial ruptures of the anterior annulus fibrosus were depicted at only MR imaging. Initially, 11 of 28 lesions were detected on MR images; retrospectively, 17 of 28 lesions were correlated with anatomic findings. CONCLUSION: Soft-tissue and intervertebral disk and ligament injuries account for 89% (25 of 28) of posttraumatic cervical spine lesions detected on postmortem images. Occult lesions, including apophyseal joint injuries, were found in clinically noninjured cervical spines. MR imaging was limited in the depiction of discrete lesions when T1-weighted non-fat-saturated, fast spin-echo T2-weighted, and gradient-echo pulse sequences were used.

Adult↗
PubMed2001

Diagnostic value of increased diffusion weighting of a steady-state free precession sequence for differentiating acute benign osteoporotic fractures from pathologic vertebral compression fractures.

BACKGROUND AND PURPOSE: Differentiating acute benign from neoplastic vertebral compression fractures can pose a problem in differential diagnosis on routine MR sequences, as signal changes can be quite similar. Our purpose was to assess the value of increasing the diffusion weighting of a diffusion-weighted steady-state free precession (SSFP) sequence for differentiating these two types of vertebral compression fractures. METHODS: Twenty-nine patients with 32 acute vertebral compression fractures caused by osteoporosis (n = 15) or malignancy (n = 17) were examined with a diffusion-weighted SSFP sequence, a T1-weighted spin-echo sequence, and a short-inversion-time inversion recovery sequence. The SSFP sequence was performed with increased diffusion weighting (delta = 0.6, 3.0, 6.0, and 9.0 ms). The signal intensities of the fractured vertebral bodies were rated on a five-point scale from markedly hypointense to markedly hyperintense relative to normal adjacent vertebral bodies. Quantitative analysis was performed by region-of-interest measurements and by calculating the bone marrow contrast ratio. Statistical analysis was performed with the Mann Whitney U test and Student's t test. RESULTS: At delta = 3 ms, the osteoporotic fractures yielded hypointense signal in seven cases, isointense signal in six, and hyperintense signal in two. The fractures showed a progressive signal loss with increased diffusion weighting, so that hypointensity was reached in all but one case. All metastatic fractures had hyperintense signal with delta = 3 and 6.0 ms. With delta = 9.0 ms, four fractures became isointense. CONCLUSION: Increasing diffusion weighting can reduce false-positive hyperintense osteoporotic fractures or make hypointensity more obvious in cases of osteoporotic fractures.

Acute Disease↗
PubMed2001

The role of ifosfamide in the treatment of relapsed and refractory lymphoma.

Ifosfamide is an alkylating agent with proven efficacy in the treatment of solid tumours and malignant lymphomas. Because it causes only mild to moderate myelosuppression, ifosfamide is often used in combination regimens with other agents. Ifosfamide has been mainly used in therapy of lymphoma as a component of salvage regimens, but high-dose ifosfamide is also effective in the mobilization of peripheral stem cells for treatment of patients with relapsed or refractory lymphoma with regimens containing autologous stem cell transplantation. Based on promising data with a new combination regimen containing idarubicin, etoposide and ifosfamide (IIVP-16) in patients with poor-risk non-Hodgkin's lymphoma, we have performed a phase II study using DIZE (dexamethasone 20 mg i.v. days 1-4, idarubicin 8 mg/m2 i.v. days 1 + 2, ifosfamide 1.0 g/m2 continuous infusion (c.i.) days 1-4, and etoposide 160 mg/m2 c.i. days 1-4) in patients with relapsed or refractory Hodgkin's and non-Hodgkin's lymphoma. In 43 evaluable patients, the response rate was 58%, including 11 complete remissions (CR) and 14 partial remissions (PR). The mean duration of response was 8 months (1-30). Myelosuppression was generally mild with mean duration of neutropenia < 1000/microL of 2.5 days (range 0-18) and thrombocytopenia < 25,000/microL of 1.5 days (0-17). Thus, DIZE is an effective and safe regimen for pretreated patients with aggressive lymphoma. These results appear to compare favourably with other salvage regimens such as IMVP-16 or DHAP. In conclusion, salvage regimens containing ifosfamide can play an important role in patients who are not eligible for high-dose chemotherapies. Moreover, ifosfamide might also have a role in reducing tumour burden and selecting those patients who qualify for HDCT.

Antineoplastic Agents, Alkylating↗
PubMed2001

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy: decrease in regional cerebral blood volume in hyperintense subcortical lesions inversely correlates with disability and cognitive performance.

BACKGROUND AND PURPOSE: Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an arteriopathic syndrome related to a genetic defect on chromosome 19. Characteristic changes in CADASIL can be observed onT2-weighted MR images in the subcortical white matter. The purpose of this study was to measure changes of regional cerebral blood volume (rCBV) with dynamic contrast-enhanced MR imaging and to correlate the changes to disability and cognitive performance. METHODS: We obtained rCBV measurements of 24 individuals with proven CADASIL on a 1.5-T MR imaging unit. A susceptibility-weighted MR imaging sequence was used for bolus tracking. Principles of the indicator dilution theory were applied to estimate values of absolute rCBV (mL/100 g). Disability was determined by using the Rankin scale, and overall cognitive performance was assessed by using the Mini-Mental State Examination. RESULTS: The mean rCBV in the subcortical white matter that was hyperintense on the T2-weighted images (2.7 +/- 0.8 mL/100 g) was significantly lower than the rCBV in the white matter that appeared normal on the T2-weighted images (4.4 +/- 1.3 mL/100 g) (P <.05). The mean rCBV in the gray matter was within the normal range (8.3 +/- 1.7 mL/100 g). Both cognitive impairment and disability negatively correlated with rCBV in the subcortical white matter that was hyperintense (P <.05) but not with rCBV in the normal appearing white matter. rCBV did not correlate with age. CONCLUSION: rCBV measured in the hyperintense subcortical white matter in individuals with CADASIL was decreased and inversely correlated with disability and cognitive impairment.

Adult↗
PubMed2000

Energy transfer in nonequilibrium space-charge-dominated beams

Space-charge modes similar to those observed in recent experiments appear in simulations of nonequilibrium charged particle beams with anisotropy. The modes couple degrees of freedom, causing energy transfer and equipartitioning without halo formation in just a few betatron wavelengths. The rate depends on a single free parameter quantifying the space-charge intensity of the final state. Traditional stability analyses are shown not to apply to high-intensity laboratory beams originating with a large perturbation from equilibrium.

Journal Article↗
PubMed2000

A comparison of paracentesis and transjugular intrahepatic portosystemic shunting in patients with ascites.

BACKGROUND: In patients with cirrhosis and ascites, creation of a transjugular intrahepatic portosystemic shunt may reduce the ascites and improve renal function. However, the benefit of this procedure as compared with that of large-volume paracentesis is uncertain. METHODS: We randomly assigned 60 patients with cirrhosis and refractory or recurrent ascites (Child-Pugh class B in 42 patients and class C in 18 patients) to treatment with a transjugular shunt (29 patients) or large-volume paracentesis (31 patients). The mean (+/-SD) duration of follow-up was 45+/-16 months among those assigned to shunting and 44+/-18 months among those assigned to paracentesis. The primary outcome was survival without liver transplantation. RESULTS: Among the patients in the shunt group, 15 died and 1 underwent liver transplantation during the study period, as compared with 23 patients and 2 patients, respectively, in the paracentesis group. The probability of survival without liver transplantation was 69 percent at one year and 58 percent at two years in the shunt group, as compared with 52 percent and 32 percent in the paracentesis group (P=0.11 for the overall comparison, by the log-rank test). In a multivariate analysis, treatment with transjugular shunting was independently associated with survival without the need for transplantation (P=0.02). At three months, 61 percent of the patients in the shunt group and 18 percent of those in the paracentesis group had no ascites (P=0.006). The frequency of hepatic encephalopathy was similar in the two groups. Of the patients assigned to paracentesis in whom this procedure was unsuccessful, 10 received a transjugular shunt a mean of 5.5+/-4 months after randomization; 4 had a response to this rescue treatment. CONCLUSIONS: In comparison with large-volume paracentesis, the creation of a transjugular intrahepatic portosystemic shunt can improve the chance of survival without liver transplantation in patients with refractory or recurrent ascites.

Adult↗
PubMed2000

Nonlinear behavior of localized space-charge waves in space-charge dominated electron beams

We present experimental observations of the abnormal growth of localized nonlinear space-charge waves in space-charge dominated electron beams passing through a resistive channel. The energy width of the space-charge waves is measured on both ends of the channel. Previous experiments had shown that, for small initial perturbations, the energy width of the slow waves increases, while the energy width of the fast waves decreases, in agreement with linear theory. We report that in the nonlinear regime (large initial perturbations), the energy width of the fast wave increases, which is unexpected, and, to the best of our knowledge, no theory exists that would predict this phenomenon.

Journal Article↗
PubMed2000

Effect of gradient and section orientation on quantitative analysis of knee joint cartilage.

The object of this study was to determine the influence of the gradient and section orientation on cartilage thickness and volume measurements in the knee joint. Eight specimens were imaged with a fat-suppressed gradient-echo sequence, applying sagittal, transverse, and coronal section orientations. Images were additionally acquired with exchanged gradient directions, and with computed tomography (CT) arthrography. After segmentation and three-dimensional (3D) reconstruction, the volume, the mean, and the maximal 3D cartilage thickness were computed. No effect of changes in the gradient orientation was found, suggesting that susceptibility-induced geometric distortion is not a relevant problem in quantitative cartilage imaging. Sagittal images produced similar data to that obtained with transverse (patella) or coronal (tibia) sections, demonstrating that all knee joint cartilages can be accurately quantified from a single sagittal data set. Whereas no significant systematic deviation between magnetic resonance imaging (MRI) and CT arthrography was recorded in the patella, there was a 10%-15% underestimation of tibial cartilage thickness in MRI.

Cartilage, Articular↗