PubMed Health⌕ Search

Biomedical subjects

R Vonthein

Publications and source records attributed to R Vonthein.

27 records · Page 2Linked to original sources
PubMed2001

[Contrast enhanced MR-angiography (CE-MRA): do contrast media with higher T1 relaxation improve imaging of carotid stenoses?].

PURPOSE: CE-MRA is a powerful tool for the non-invasive evaluation of carotid artery occlusive disease. However, due to certain drawbacks, it has not completely replaced DSA. The purpose of this study was to evaluate if Gd-BOPTA, a contrast agent with high T1 relaxivity, can increase the diagnostic accuracy of CE-MRA. MATERIAL AND METHODS: The CE-MRA examinations of 54 consecutive patients were evaluated by two experienced radiologists, independently. The examinations of 27 patients were contrasted either with 20 ml Gd-BOPTA or with 20 ml Gd-DTPA. The reviewers were blinded to the contrast agent chosen and to the ultrasound results. They rated the overall image quality and the degree of the ICA stenoses. RESULTS: For the estimation of the degree of the ICA stenoses there was a high interrater validity. In comparison to the ultrasound findings, 6 of 50 high-degree stenoses were underestimated as moderate stenoses. In one of seven sonographically occluded vessels, MRA revealed residual patency in the vessel lumen. It was not possible to identify the contrast agent that was taken for a study. Subjective estimation of the image quality (arterial contrast of the ICA, contrast of the other vessels, and general impression) did not significantly change with the contrast agent employed. CONCLUSION: The diagnostic accuracy of CE-MRA for the evaluation of internal carotid artery stenoses is not improved by Gd-BOPTA if identical volumina of contrast media are applied. The potential of this contrast agent can be the reduction of the amount of contrast without loss of diagnostic information. Further studies are necessary.

Aged↗
PubMed2001

Therapeutic drug monitoring of clozapine in relapse prevention: a five-year prospective study.

Twenty-three outpatients with schizophrenia (ICD-10 F20.xx) treated with clozapine (CZ) as monotherapy entered a prospective study on relapse prevention. Every 4 weeks, psychopathology was assessed by the Brief Psychiatric Rating Scale (BPRS), and plasma CZ and norclozapine levels were measured. Patients were enrolled after complete remission of positive symptoms for at least 4 months according to the psychosis cluster of the BPRS and at a mean of 3.3 years after their last hospitalization. At the time of enrollment, the median BPRS total score was 29 points (range, 19-48). Within 4 months, the baseline CZ plasma level was established as the mean of CZ levels from at least four subsequent measurements. These baseline plasma levels were considered as the optimal relapse-preventing plasma CZ levels in the individual patients. When the patients were enrolled, they were considered to be prone to relapse. Relapse was defined as clinical deterioration, hospitalization, or both. Plasma levels were considered a prognostic factor, and patients were defined as at increased risk if plasma levels decreased by more than 40% from baseline CZ plasma level. The effect of plasma CZ levels on clinical outcome was evaluated by a Cox regression with plasma level as a time-dependent covariate. Within 46 months of enrollment, 32 episodes of relapse events in 10 patients were available for evaluation. Seventeen patients had a plasma level decrease of more than 40% at some point. In 12 of these, the decrease was present for more than 12% of the observation period. Eight patients of this group relapsed, and three of these had to be rehospitalized. Two patients relapsed, although their plasma levels decreased by more than 40% for less than 12% of the observation period. Within the first 2 years, relapse-free survival curves illustrate that both groups (episodes under elevated risk and episodes not under elevated risk) had identical relapse patterns, but from then on the relapse risk increased rapidly in the group with longer exposure to elevated risk. In a Cox model with a 40% decrease of plasma CZ levels as a dichotomous time-varying explanatory covariate, the risk ratio is 6 (95% confidence interval = 2-19, p = 0.003). The 10 patients who relapsed exhibited safe plasma levels (less than a 40% decrease from their baseline levels) for only 210 months, and 13 nonrelapsing patients had plasma levels defined as safe for 426 months.

Antipsychotic Agents↗
PubMed2001

L- and M-cone-driven electroretinograms in Stargardt's macular dystrophy-fundus flavimaculatus.

PURPOSE: To study the dynamics of the long (L)- and middle (M)-wavelength-sensitive cone-driven pathways and their interactions in patients with Stargardt's macular dystrophy-fundus flavimaculatus (SMD-FF) and to correlate them with other clinical parameters and individual genotypes. METHODS: Forty-seven patients with SMD-FF participated in the study. In addition to standard 30-Hz flicker electroretinograms (30-Hz fERG), ERG responses were measured to stimuli that modulated exclusively the L or the M cones (L/M cones) or the two simultaneously. Blood samples were screened for mutations in the 50 exons of the ABCA4 gene. RESULTS: Patients with SMD-FF did not show a decrease in the mean L/M-cone-driven ERG sensitivity, but there was a significant increase in the interindividual variability. The mean L-/M-cone weighting ratio was normal. However, the L-cone-driven ERG was significantly phase delayed, whereas the M-cone-driven ERG was significantly phase advanced. These phase changes were significantly correlated with disease duration. The amplitude and implicit time of the standard 30-Hz fERG both correlated significantly with the L/M-cone-driven ERG sensitivity and with the phase difference between the L/M-cone-driven ERGs, indicating the complex origin of the standard 30-Hz fERG. Probable disease-associated mutations in the ABCA4 gene were found in 40 of 45 patients, suggesting that they form a genetically fairly uniform SMD-FF study group. There was no correlation between the genotype and the L/M-cone-driven ERGS: CONCLUSIONS: The changes in L/M-cone-driven ERG sensitivity and phase possibly represent two independent disease processes. The phase changes are similar to those found in patients with retinitis pigmentosa and possibly are a general feature of retinal dystrophies.

ATP-Binding Cassette Transporters↗
PubMed2000

[High resolution multislice CT of the lung: comparison with sequential HRCT slices].

PURPOSE: To compare the image quality of high-resolution (HR) spiral CT scans from a multislice CT scanner with sequential HRCT scans from a singleslice CT scanner. MATERIALS AND METHODS: 20 patients with diffuse lung disease received a high-resolution spiral CT on a multislice scanner (4 slices) and 5 HRCT single slices (1 mm) on a singleslice scanner. Scan parameters of the multislice scanner were: Collimation 4 x 1 mm, pitch 6, slice thickness 1 mm. 5 HRCT slices were compared to the corresponding HR spiral CT slices using a 5-point scale by 5 radiologists with regard to the image quality and the number of artifacts. The evaluation was performed with a multivariate analysis (MANOVA test). RESULTS: Overall impression of image quality, noise, central vessels and bronchi, and all pathological changes were not significantly different between the two CT methods. Sequential HRCT scans were considered to be significantly better than HR spiral CT scans for spatial resolution (p = 0.02), depiction of peripheral vessels (p = 0.02), and of small bronchi (p = 0.05), and significantly worse for depiction of interlobar septa (p < 0.001). Diagnostically relevant differences were found in only 2.2%. Breathing and heartbeat artifacts each were 3 times higher in the sequential HRCT technique than in the multislice-spiral technique (p < 0.0001). CONCLUSION: HR spiral CT scans performed on a multislice CT scanner provide significantly less artifacts and an equal diagnostic image quality compared to sequential HRCT scans performed on a singleslice CT scanner. Multislice spiral CT in HR technique may replace the common scanning technique with conventional spiral CT and additional HRCT scans for diffuse lung diseases.

Adult↗
PubMed1999

Immobility as a major cause of bone remodeling in residents of a long-stay geriatric ward.

Residents of a long-stay geriatric ward at the University Hospital Basel were included in a study to investigate the effects of hypovitaminosis D and immobility. All 91 women (mean age 82.5 years) and 92 men (mean age 78.7 years) were enrolled in the study. Measurements included bone resorption, as measured by urinary deoxypyridinoline (dpd), serum 25-hydroxyvitamin D (25OHD), serum intact parathyroid hormone (iPTH), and their correlations with a four grade mobility score. Mobility score reflected the degree of weight bearing, ranging from walking independently to primarily bed bound. In 86% of all residents, serum 25OHD levels were below the normal limit of 12 ng/ml. Secondary hyperparathyroidism (HPT) was detected in 24% of all patients, using 55 pg/ml as the upper limit for serum iPTH. No significant correlation was found between urinary dpd and serum 25OHD or serum iPTH. Mobility index and both urinary dpd (f: P = 0.001, r = 0.37; m: P < 0.0001, r = 0.47) and serum calcium (female: P = 0.007, r = 0.28; male: P = 0.02, r = 0.24) were positively related. In institutionalized elderly people with a high prevalence of vitamin D deficiency serum intact PTH levels did not correlate with bone resorption as measured by urinary deoxypyridinolin. However, more immobile subjects had significantly higher excretion rates for urinary dpd and higher serum calcium levels. Our results suggest that in elderly people immobility may contribute to bone loss that might preempt the development of secondary HPT through elevation of serum calcium.

Activities of Daily Living↗
PubMed1999

Muscle strength in the elderly: its relation to vitamin D metabolites.

OBJECTIVE: To identify a relation between loss of muscle strength and vitamin D deficiency in ambulatory elderly persons not receiving vitamin D supplementation. DESIGN: Cross-sectional study. SETTING: All measurements were taken at the Department of Geriatrics, University Hospital, Basel, Switzerland. SUBJECTS: Three hundred nineteen patients (103 women, 216 men) selected by random sampling from participants in an ongoing interdisciplinary study on aging (mean age for women, 74.2 yrs; for men, 76.7 yrs). OUTCOME MEASURES: Leg extension power (LEP) and body mass index (BMI); serum values of 25-hydroxyvitamin D [calcidiol, 25(OH)D], 1,25-hydroxyvitamin D [calcitriol, 1,25(OH)2D], and intact parathyroid hormone (iPHT). RESULTS: Twelve percent of women and 18% of men had 25(OH)D values below the normal range (<12 ng/mL). Muscle strength was lower in older subjects (female: r = -.35; p = .0005/male: r = -.48; p < .0001) and was lower in women than in men (p < .0001). In men both 25(OH)D and 1,25(OH)2D was significantly correlated with LEP (r = 0.24; p = .0004/r = .14; p = .045). In women, only 1,25(OH)2D was significantly correlated with LEP (r = 0.22; p = .034). In an ANCOVA including all participants and explaining LEP by sex, age, BMI, 1,25(OH)2D, 25(OH)D, and iPTH, all factors showed significant effects except 25(OH)D and iPTH (r2 = .41). CONCLUSION: Muscle strength declined with age in ambulatory elderly people and showed modest, but significant, positive correlation with 1,25(OH)2 vitamin D in both sexes and with 25(OH)D in male subjects. Therefore vitamin D deficiency appears to contribute to the age-related loss of muscle strength, which might be more pronounced in institutionalized elderly people with a high prevalence of vitamin D deficiency.

Aged↗
PubMedDate not supplied

Evaluation of glaucomatous visual field loss with locally condensed grids using fundus-oriented perimetry (FOP).

PURPOSE: We compared detection rates of glaucomatous visual field defects (VFDs) between a conventional rectangular stimulus grid and locally condensed test point arrangements in morphologically suspicious regions. METHODS: Humphrey Field Analyzer model 630 (HFA I, program 30-2 with a rectangular 6 degrees x 6 degrees grid) was used as the conventional perimetric method. Individual local test-point condensation was realized by fundus-oriented perimetry (FOP) on the Tuebingen Computer Campimeter (TCC). RESULTS: Of a total of 66 glaucoma patients, or suspected sufferers, 23 showed normal findings and 27 showed pathological findings with both methods. In 15 cases we found normal visual fields in HFA 30-2, whereas FOP revealed early glaucomatous functional damage. Only one case showed pathological HFA results, while FOP was normal. Detection rates of VFDs significantly differed between the two methods (p < 0.001; sign test). CONCLUSIONS: FOP, using individually condensed test grids, significantly increases detection rates of glaucomatous VFDs in morphologically suspicuous areas compared with a conventional HFA 30-2 technique using equidistant rectangular (6 degrees x 6 degrees) test point arrangements.

Adolescent↗
PubMedDate not supplied

Cytokines, cytokine antagonists and soluble adhesion molecules in patients with ocular Behçet's disease treated with human recombinant interferon-alpha2a. Results of an open study and review of the literature.

OBJECTIVE: To elucidate the influence that interferon-alpha exerts on the cytokine network in active ocular Behçet's disease (BD). METHODS: Fifty patients with active ocular BD were treated with human recombinant interferon-alpha2a (rhIFN-alpha2a). Serum was analysed for the presence of IL-10, TNF-alpha, IL-8, IL-6, sIL-2R, IFN-gamma, IFN-alpha, IL-12, IL-4, sTNFRI (p55), sTNFRII (p75), IL-1RA, G-CSF, sE-selectin, sVCAM-1, sICAM-1 and neopterin before initiation of and at several time points during IFN treatment and compared to 21 healthy controls. RESULTS: The levels of IFN-alpha IL1-RA and sTNFRII were significantly increased in the patients at baseline in comparison to healthy controls. During treatment with rhIFN-alpha2a, when remission was achieved as defined by the scoring system used, a significant increase in levels of IFN-alpha, IL-2R, TNF-alpha, sTNF-RII, sICAM-1, sVCAM-1, neopterin in the serum was observed, with a tendency towards increased IL-1RA as well. In contrast, leuko- and thrombocyte counts and sE-selectin serum levels significantly decreased. Positive correlations were found between IFN dosage or serum levels and sVCAM-I, neopterin, sTNF-RII and sIL-2R, between sVCAM-1, sIL-2R, TNF-alpha, sTNF-RII and neopterin, sICAM-I and sVCAM-1, sIL2-R and sTNF-RII, and, finally, between sIL2-R and sICAM-I. CONCLUSIONS: IFN-alpha exerts diverse influences mainly on cytokine antagonists and soluble adhesion molecules. Because sTNF-RII and IL-1RA were increased by IFN-alpha treatment, these might be interesting alternative treatment options in refractory BD. Some of the side-effects of IFN-alpha may be caused by activation of monocytes, which is reflected by an increase in neopterin serum levels.

Antiviral Agents↗