PubMed Health⌕ Search

Biomedical subjects

M Weiss

Publications and source records attributed to M Weiss.

At least 109 records · Page 6Linked to original sources
PubMed2001

X-ray magneto-optics in lanthanides.

Magneto-optical methods in the visible light regime generally lack element specificity, which has become a considerable shortcoming in research on advanced heteromagnetic systems. Using circularly polarized soft x rays tuned to a 4d-4f core-level transition of a lanthanide element, the specularly reflected x-ray intensity changes proportionally to the magnetization of this element and, e.g., hystereses are easily measured element specifically. In contrast to the case of visible light, temperature dependent 4d-4f magneto-optical signals are not influenced by the thermal lattice expansion.

Journal Article↗
PubMed2001

Magnetic moments at the surface of antiferromagnetic NiO(100).

The orientation of magnetic moments at the (100) surface of antiferromagnetic NiO single crystals is studied by x-ray linear magnetic dichroism in photoemission microscopy. T domains are observed terminating at the surface, with domain boundaries running mostly along in-plane [10] directions. From the detailed polarization dependence we find that the magnetic surface structure of a cleaved crystal is bulk terminated. This is in contrast to sputtered surfaces, where magnetic moments lie within the surface plane, forming a magnetically relaxed structure. These findings are of importance for understanding the exchange bias phenomenon.

Journal Article↗
PubMed2001

Clonotypic polymerase chain reaction confirms minimal residual disease in CLL nodular PR: results from a sequential treatment CLL protocol.

Patient-tumor-specific oligonucleotides were generated for the detection of minimal residual disease (MRD) in a highly specific and sensitive clonotypic polymerase chain reaction (cPCR). The clone-specific region of highest diversity, CDR-III, was PCR amplified and sequenced. Nested CDR-III clonotypic primers were used in a semi-nested cPCR with a sensitivity of at least 1 in 10(5) cells. Patients with protocol-eligible Rai intermediate or high-risk chronic lymphocytic leukemia (CLL) received induction with fludarabine 25 mg/m(2) per day for 5 days every 4 weeks for 6 cycles, followed by consolidative high-dose cyclophosphamide (1.5, 2.25, or 3g/m(2)). cPCR was performed on peripheral blood and bone marrow mononuclear cells. All 5 patients achieving a clinical partial remission (PR) studied by cPCR were positive. Five patients achieved nodular PR (nPR) (residual nodules or suspicious lymphocytic infiltrates in a bone marrow biopsy as the sole suggestion of residual disease). Five of 5 patients with nPR were cPCR positive. In contrast, flow cytometry for CD5-CD19 dual staining and kappa--lambda clonal excess detected MRD in only 3 of the same 5 nPR patients, all of whom were cPCR positive, and immunohistochemistry detected MRD in only 1 of 4 assessable patients. Three of 7 CR patients evaluable by cPCR had MRD. Only 1 CR patient had MRD by flow cytometry; that patient was also cPCR positive. These data support the conclusions that nodular PR in CLL represents MRD and that clonotypic PCR detects MRD in CLL more frequently than flow cytometry or immunohistochemistry. (Blood. 2001;97:1929-1936)

Antigens, CD↗
PubMed2001

Dissociation of LPS-induced monocytic ex vivo production of granulocyte colony-stimulating factor (G-CSF) and TNF-alpha in patients with septic shock.

Over a 6 month period, in 192 patients admitted to the intensive care unit (ICU), a longitudinal analysis of whole blood lipopolysaccharide (LPS)-induced ex vivo cytokine production was performed on a daily basis until discharge from the ICU or death. Twenty-one patients with proven infections were in septic shock for the first time and for at least 3 days' duration. Ex vivo LPS-inducible release of granulocyte colony-stimulating factor (G-CSF) was upregulated and that of TNF-alpha was downregulated in patients with septic shock, regardless whether they survived or died. In conclusion, LPS-induced ex vivo TNF-alpha and G-CSF cytokine release by monocytes is regulated differentially in patients with septic shock. Since upregulation of LPS-induced production of G-CSF occurred earlier in survivors than in non-survivors, rapidly elevated and sustained G-CSF responsiveness may contribute to survival in septic shock.

Adult↗
PubMed2001

[The NACA scale. Construct and predictive validity of the NACA scale for prehospital severity rating in trauma patients].

The NACA-scale is used in many Austrian, German and Swiss emergency medical systems for demographic description of emergency patients. Little attention has been payed to the evaluation of its construct and predictive validity. In 427 consecutive trauma patients rescued in primary mission the NACA-Scale and the Injury Severity Score (ISS) were determined. Outcome data were obtained from medical charts and by written or telephone requests. Data were analysed with Spearman-Rank-Correlation. NACA-Grade and ISS-values showed only a moderate correlation with a considerably large spread (Rho = 0.721). Both severity scores demonstrated a good correlation to mortality (Rho = 0.976/0.994) and to transfer to an ICU (Rho = 0.964/0.943), as well a moderate correlation to the duration of ICU-stay (Rho = 0.722/0.756) and of hospital stay (Rho = 0.558/0.694). The NACA-scale adequately describes life threat in trauma victims and correlates well with morbidity and mortality. Thus, it is a valuable tool for demographic purposes in emergency medical systems. For more precise prehospital severity rating in trauma patients, the NACA-scale should be supplemented or replaced by a physiologically based prehospital severity score.

Adult↗
PubMed2001

[Endotracheal intubation of patients with Pierre-Robin sequence. Successful use of video intubation laryngoscope].

Patients with Pierre Robin sequence are a classic model for patients with a difficult airway. In these patients tracheal intubation may be facilitated using the lateral approach. In a 3-day-old newborn with Pierre Robin sequence, scheduled for anaesthesia to take a mould of the cleft palate, we used a video-intubation laryngoscope to give a video-display of the lateral approach intubation technique to the junior colleagues. The video-laryngoscopic view allowed detailed demonstration of the intubation procedure to all persons present. In addition, video-transmission of the laryngoscope picture enabled the attendant anaesthetist to quickly recognise the need for suctioning the hypopharynx and to coordinate the direction and extent of laryngeal pressure according the video-laryngoscopic findings. Of special value for the intuboscopist was the improved view of the cords provided by the video-display compared with direct laryngoscopy. This facilitated a non-traumatic insertion of the tube into the trachea and allowed reliable confirmation of the intubation depth by the tube marking between the vocal cords.

Humans↗
PubMed2001

Infusion pump performance with vertical displacement: effect of syringe pump and assembly type.

OBJECTIVE: To evaluate the effect of different infusion pump models on continuity of drug delivery during vertical displacement of syringe pumps. DESIGN: Zero-drug delivery time (ZDDT), retrograde aspiration volume, and infusion bolus were recorded using the same syringe in three different models of syringe pump after lowering and elevating the pump. Compliance of each infusion assembly was measured using the occlusion release technique at 38 mmHg. RESULTS: Lowering the pump by 50 cm at an infusion rate of 1 ml/h resulted in ZDDT values ranging from 2.78 +/- 0.29 to 5.99 +/- 1.09 min. Elevating the syringe pump to its original position caused infusion boluses between 44.1 +/- 3.2 and 77.1 +/- 5.1 microl. The results demonstrated that there are large differences between syringe pump models (F = 66.8, df = 2/33, p < 0.0001) and between pumps of the same model (F = 21.3, df = 1/34, p < 0.0001). A similar pattern was found in retrograde aspiration volume and infusion bolus. CONCLUSION: All tested pumps led to clinically relevant flow irregularities during vertical displacement of the syringe pump. Thus, vertical displacement of any syringe pump connected to an infusion line delivering highly potent drugs at low infusion rates should be avoided. The variability across syringe pumps indicates that syringe pump design remains an area of potential further improvement for reducing the risk of adverse patient events.

Analysis of Variance↗
PubMed2001

Evaluation of a simple method for minimizing iatrogenic blood loss from discard volumes in critically ill newborns and children.

OBJECTIVE: To validate a simple method avoiding discard volumes in pediatric patients with indwelling arterial and venous lines. DESIGN: Zero-discarding was achieved by passive extracorporeal arteriovenous backflow via standard single pressure transducer equipment. We tested backflow distances (10, 20 and 30 cm beyond the sampling port), corresponding to withdrawal volumes of 0.6 ml, 0.8 ml and 1.0 ml, respectively, in comparison to conventional sampling with discard of 0.6 ml. With the backflow technique, the "withdrawal volume" was flushed back to the patient after sampling. We enrolled 120 patients who were allocated to either of the following paired sampling procedures: 10 cm versus conventional, 20 cm versus conventional, 30 cm versus conventional and two paired conventional samples. The order of the sampling was randomly allocated. Bias and precision were determined using Bland-Altman diagrams and algorithms. RESULTS: No appreciable difference was found for blood gases, hemoglobin, potassium and calcium between the backflow technique and conventional sampling. Sodium results and blood glucose showed a bias towards higher values with the backflow technique (mean difference, sodium, 0.9 mmol/l; glucose, mean difference 0.5 mmol/l, standard deviation 0.44 mmol/l). CONCLUSIONS: The backflow technique provides reliable results for blood gases and electrolytes. However, in patients at risk of hypoglycemia, the backflow method should not be used to monitor blood glucose levels.

Blood Gas Analysis↗
PubMed2001

Hepato-splanchnic metabolic effects of the stable prostacyclin analogue iloprost in patients with septic shock.

OBJECTIVE: To evaluate the effects of the stable prostacyclin analogue iloprost on hepato-splanchnic blood flow, oxygen exchange and metabolism in patients with septic shock. DESIGN: Prospective clinical study. SETTING: Intensive care unit in a university clinic. PATIENTS: Eleven patients with septic shock requiring norepinephrine to maintain mean arterial pressure above 70 mmHg. INTERVENTIONS: Iloprost was incrementally infused to increase cardiac index by 15%. MEASUREMENTS AND MAIN RESULTS: Splanchnic blood flow (Qspl) was measured using the steady-state indocyanine-green infusion technique and endogenous glucose production rate (EGP) using a stable isotope approach. Systemic and splanchnic oxygen consumption (VO2), the hepato-splanchnic uptake rates of the glucose precursors lactate, pyruvate, alanine and glutamine, the hepatic venous redox state and gastric mucosal-arterial PCO2 gradients were determined. After a baseline measurement, iloprost infusion was started. After 90 min all measurements were repeated and a third measurement was obtained after another 90 min following iloprost withdrawal. Qspl (baseline I: 0.82/0.75-1.08 l x min x m2; iloprost: 0.94/0.88-1.29 l x min x m2; baseline II: 0.87/0.74-1.09 l x min x m2) and splanchnic oxygen delivery (baseline I: 122/103-166 ml x min x m2; iloprost: 134/117-203 ml x min x m2; baseline II: 130/98-158 ml x min x m2) significantly increased. While systemic VO2 significantly increased (baseline I: 139/131-142 ml x min x m2; iloprost: 147/136-164 ml x min x m2; baseline II: 143/133-154 ml x min x m2) splanchnic VO2 increased in 9 of 11 patients which, however, did not reach statistical significance. EGP significantly decreased (baseline I: 23/16-26 micromol x kg x min; iloprost: 16/14-21 micromol x kg x min; baseline II: 18/12-20 micromol x kg x min), whereas all other parameters of energy metabolism remained unchanged. CONCLUSION: In patients with septic shock an iloprost-induced increase in cardiac index increased splanchnic blood flow and shifted oxygen utilization from the energy requiring de novo glucose production rate to other oxygen-demanding metabolic pathways.

Adult↗
PubMed2001

Human herpes virus type 7 DNA in the cerebrospinal fluid of children with central nervous system diseases.

UNLABELLED: Human herpes virus type 7 (HHV-7) has been associated with unspecific febrile syndrome, exanthem subitum (ES), viral rashes and Epstein-Barr virus (EBV) like syndrome. Neurological complications such as hemiplegia or seizures have been described in a few children with ES. Whether HHV-7 may also affect the CNS in the absence of ES is unknown. In this study, we investigated CSF samples from children with different neurological diseases for the presence of HHV-7 specific DNA. A HHV-7 specific nested polymerase chain reaction (PCR) was established amplifying a 478 bp DNA sequence of the glycoprotein U23 of HHV-7 strain SB. 68 children with CNS diseases with inflammatory CSF findings (n = 24), CNS diseases without inflammatory CSF findings (n = 18) and febrile seizures (n = 26) were examined. A total of 26 children with infectious diseases in the absence of neurological disease and 11 children without signs of a peripheral infection and without neurological disease served as controls. The CSF samples of six children from the study groups were HHV-7 PCR positive, but none from the controls. These children were diagnosed with aseptic meningitis (n = 1), viral encephalitis/meningoencephalitis (n = 2), facial palsy (n = 1), vestibular neuritis (n = 1) and febrile seizure (n = 1). CONCLUSION: These results indicate that human herpes virus type 7 infection is associated with central nervous system disease in children and should be considered in children whether inflammation in the cerebrospinal fluid is present or not.

Adolescent↗
PubMed2001

Readiness potential in different states of physical activation and after ingestion of taurine and/or caffeine containing drinks.

To investigate the influence of taurine and caffeine containing drinks and physical stress on the cortical movement-preparation, the readiness potentials or "Bereitschaftspotentiale" (BPs), preceding voluntary self-placed pedalling movements, were examined after different states of exhaustion on an ergometer. 15 (13 right-handed) healthy men, aged between 22-30, participated in a randomised, cross over, double-blind, placebo controlled study. BPs were averaged out of artefact free EEG-segments from more than 90 triggered events, measured at 17 electrodes of the 10:20 system. With increasing effort the BPs were enlarged differently depending on the drink consumed. In placebo trials after exhaustive exercise premovement negative potential curves could be seen even in frontal areas. With caffeine the BPs increased after lower workload, achieving a level, which was reached in the placebo trials only after submaximal physical activation. Furthermore a significant shortening of premovement-brain-potentials in frontal and parietal regions could be seen in the caffeine trials at rest. Taurine admixture seems to inhibit this effects.

Adult↗
PubMed2001

The influence of a taurine containing drink on cardiac parameters before and after exercise measured by echocardiography.

To determine the effect of the taurine containing drink "Red Bull" on cardiac parameters thirteen endurance trained subjects performed an exhaustive bout of endurance exercise at three different times. Prior to the exercise the original "Red Bull" drink, a similar drink without taurine, containing caffeine, and a "placebo" drink without caffeine and without taurine were ingested by the subjects in a double-blind cross-over design. Echocardiographic examinations were performed before the drinks, 40 minutes after the drinks prior to the exercise and in the regeneration period after exercise. Stroke volume was significantly influenced only in the "Red Bull group" (80,4+/-21,4 ml before drink vs. 97,5+/-26,2 ml in the regeneration period), mainly due to a reduced endsystolic diameter and volume. Furthermore in this group the peak late diastolic inflow (V(A)) in the regeneration period was significantly higher compared with the pre-exercise levels. This observation was also made in the caffeine group but without any consequences on ventricular function. The results of the present study show an influence of the original caffeine and taurine containing drink (Red Bull) on parameters of the cardiac contractility.

Adult↗
PubMed2001

Induction therapy of adult acute lymphocytic leukemia without the use of vincristine or prednisone.

In the last 30 years, a multitude of treatment regimens for adult acute lymphocytic leukemia (ALL) has been developed. Essentially, all of these regimens use an induction therapy vincristine, prednisone, and an anthracycline intensified with L-asparaginase or cyclophosphamide. Though such regimens induce most patients to enter a remission, relapse is frequent, and most adult patients ultimately die of their disease. The author postulated that further refinements in this approach to induction therapy were unlikely to markedly improve treatment results in this disease. Therefore, the author is studying a new intensive strategy using cytarabine with a single very high dose of mitoxantrone (without vincristine or prednisone) as induction therapy for adult patients with ALL.

Adolescent↗
PubMed2001

Modeling heterogeneity of properties and random effects in drug dissolution.

PURPOSE: To investigate new models characterizing dissolution data obtained for heterogenous materials (model I) and under randomly time-varying conditions (model II). METHODS: In model I, the heterogeneity of the dissolving substance introduces variation of the fractional dissolution rate. In model II, the fractional dissolution rate evolves randomly, and thus the dissolution has the characteristics of a stochastic process. This situation is studied for the constant and time-dependent means of the dissolution rate. RESULTS: The time dynamics of the dissolved fraction is presented for model I. The standard characteristics of dissolution are derived under general conditions and for several examples. One of them is in accordance with a function found empirically (1). A duality between the time-dependency of the fractional dissolution rate and the heterogeneity of the substance is investigated. The mean and variance of the dissolved fraction are calculated for model II. A method for estimating the mean dissolution rate is proposed and illustrated using Monte-Carlo experiments. CONCLUSIONS: It follows from model I that the heterogeneity, with the same mean properties, slows down the dissolution with respect to the homogeneous case. The second approach permits predictions about the role of the stochastic fluctuations of the dissolution rate and to establish the boundaries for the dissolution profiles.

Models, Biological↗