Search PubMed⌕ Search

Biomedical subjects

A Weber

Publications and source records attributed to A Weber.

At least 145 records · Page 8Linked to original sources
PubMed1999

[Use of open MRI in head-neck surgery].

The vertical open MRI (Signa SP, 0, 5 Tesla) is ideal for interventional diagnosis and therapy. From our point of view indications in Otorhinolaryngology are biopsies of tumours which are difficult to access such as the petrous apex and the petroclival region, the parapharyngeal space and neck and the orbit. Furthermore the open MRI is useful in the surgery of paranasal sinuses, in the evaluation of tissue-resection and helpful in detection of the anatomy of delicate structures as the internal carotid artery, the skull-base and the orbit. Also navigation in open MRI is possible for example with a flash-point-system. The advantage to conventional navigation systems is the possibility of real-time-imaging, which allows detection of tissue shift occurring during the procedure. We report about our experience with ten biopsies of the petrous apex and the petroclival junction and two biopsy of the parapharyngeal space and the neck. Further experience was gained with MR guided placement of afterloading tubes into large neck metastases in three cases and microscopic surgery of paranasal sinuses in five cases. In all operative procedures an excellent resolution was found especially for soft tissue structures as for example blood vessels. With the aid of special pointer systems or artefacts by surgical instruments all relevant anatomical structures could be detected intraoperatively, concerning normal and pathologic tissue. Thus open MRI proved to be a helpful instrument in these operative procedures.

Adult↗
PubMed1999

Immunoglobulin deficiency and determination of pneumococcal antibody titers in patients with therapy-refractory recurrent rhinosinusitis.

We examined 245 patients with chronic rhinosinusitis not responding to prolonged antibiotic treatment and tested each patient for humoral antibody deficiencies. Low immunoglobulin levels were found in 22 patients. Five of them had defects of two or more immunoglobulin isotypes that were diagnosed as common variable immunodeficiency (CVI). Seventeen had an IgG-subclass deficiency. Before and after immunization with pneumococcal vaccine, serotype-specific pneumococcal antibody levels were determined to further evaluate the relevance of the underlying deficiency. Significantly reduced antibody titers of pneumococcal serotypes were found in CVI patients (n = 5), while immunization of 17 patients with IgG-subclass deficiency gave different results. Three of the 17 patients responded poorly to pneumococcal immunization and were prone to a polysaccharide specific immunodeficiency. Patients with CVI or IgG-subclass deficiency failing to produce protective antibody levels in more than five serotypes were chosen for antibiotic and/or immunoglobulin substitution therapy. Since recurrent sinusitis in these patients did not resolve with adequate conservative therapy, endonasal microsurgery was then performed and was seen to be a valuable therapeutic option. Our study suggests that an IgG-subclass deficiency may be the first sign of a basic immunological change, resulting in persisting sinus infections.

Adolescent↗
PubMed1999

New telemetric system for daily pulmonary function surveillance of lung transplant recipients.

BACKGROUND: Following lung transplantation, prompt diagnosis and therapy of acute pulmonary rejection and infection episodes relies primarily upon changes in pulmonary function and determines long-term outcome. We tested a new system that allows daily monitoring of the patient's pulmonary status even after discharge from the hospital. METHODS: Seven lung transplant recipients from our center were equipped with a telemetric monitoring device consisting of a portable flowmeter and a special modem unit. The flowmeter measures forced vital capacity (FVC), forced expiratory volume per second (FEV1), and mid expiratory flows (MEFs), encodes information like fever, cough, and dyspnea in a binary code form, and stores all values in a 32 kB memory unit. After its use, the patient positions the flowmeter onto the modem unit which automatically connects to a central computer at our center to transfer all saved data. The whole set can be used via any regular phone jack. The patient's file in the computer can be checked every day. RESULTS: All patients learned to use the unit during their postoperative stay or during later follow-up, and were able to apply the system at home. In a mean follow-up period of 10.3+/-2.2 months, 15 episodes of significant deterioration in home pulmonary function tests (PFTs) (>10%) were registered in 6 patients, which were all confirmed by in-hospital body plethysmography. They resulted in diagnoses of 4 episodes of acute rejection, 6 cases of beginning bacterial pneumonia, and 5 cases of, most likely, viral tracheobronchitis. Only 1 patient had to be admitted to the hospital. All patients PFTs returned to previous values after treatment. CONCLUSIONS: Telemetric monitoring of graft function in lung transplant recipients allows reliable early diagnosis and treatment of infection or rejection, which might help to prevent exacerbation of the pathology and reduce quantity of amounting graft dysfunction.

Forced Expiratory Volume↗
PubMed1999

Who says you can't treat pituitary carcinoma on a breast board?

A hospital-manufactured aquaplast head and neck immobilization system was constructed in tandem with a unique custom-built breast board. It was developed in conjunction with the breast board for patients unable to achieve and maintain the desired head flexion needed in the treatment of pituitary lesions. (This custom design provides an alternative to accomplishing this desired head angle needed to position the patient's eyes out of the treatment area, realizing that the lenses are situated in the anterior 1 cm of the globes.) By using the angled breast board, reproducibility of setup and patient comfort were addressed throughout the simulation, computed tomography planning and treatment process. The custom designed boards were constructed with available materials at relatively low cost to the department.

Equipment Design↗
PubMed1999

Alterations of bacterial clearance induced by propofol.

BACKGROUND: The purpose of the study was to investigate the potential influence of the anaesthetic agent propofol on immune function in terms of systemic clearance and organ distribution of injected Escherichia coli in a rabbit model. METHODS: Defined numbers of E. coli (1.3 x 10(8) colony-forming units, CFU) were injected intravenously 1 h after starting a 4-h infusion of the anaesthetic propofol (2 ml.kg-1.h-1, Disoprivan 1%; n = 6)) or after saline application (n = 6). As propofol is formulated in a 10% lipid emulsion, the lipid vehicle Intralipid (2 ml.kg-1.h-1; n = 6) alone was investigated in a separate group. Parameters monitored were arterial pressure and rates of bacterial elimination from the blood. Three hours after bacterial injection, the animals were killed, and tissue samples of liver, spleen, lung, and kidney were collected for microbiological examinations. RESULTS: Compared to saline-treated animals, infusion of propofol induced increased accumulation of E. coli in lung and spleen, thus reflecting reticuloendothelial system dysfunction. CONCLUSION: As the lipid emulsion by itself induced the same effects, the impaired immune function due to propofol is thought to be attributed to its solvent Intralipid.

Anesthetics, Intravenous↗
PubMed1999

Means of increasing sensitivity of an in vitro diagnostic test for aspirin intolerance.

BACKGROUND: Pseudo-allergic reactions caused by aspirin (acetyl salicylic acid; ASA) often resemble immediate-type hypersensitivity reactions consisting of urticaria and angioedema or rhinoconjunctivitis, asthma and nasal polyps. In the last few years, a new in vitro assay based on determination of sulfidoleucotrienes from isolated leucocytes (cellular allergen stimulation test - CAST) has been introduced for type I allergies and pseudoallergic reactions. In ASA intolerance, there is only limited experience using this assay with - in some studies - only moderate sensitivity. Furthermore, the necessity to use freshly isolated leucocytes from untreated patients is inconvenient for routine settings. OBJECTIVE: The purpose of our study was to search for possibilities of increasing the sensitivity of the test and to use stored blood samples which would permit shipping, two requirements for the clinical suitability of this test. PATIENTS AND METHODS: Leucotriene release in response to ASA and other non-steroidal anti-inflammatory drugs (NSAIDs) was analysed in 38 ASA-intolerant patients (predominantly airway-related symptoms n = 22; predominantly cutaneous symptoms n = 16) and 50 controls. The diagnosis of ASA intolerance was established by history and placebo-controlled oral challenge tests. RESULTS: Using 24 h-stored leucocytes obtained from 10 ASA-intolerant patients and 10 healthy controls there were no significant differences of leucotriene release by resting, ionomycin-, and anti FcepsilonRIalpha-stimulated leucocytes compared with freshly isolated leucocytes. Analysis of ASA + C5a-mediated leucotriene release by stored blood samples in combination with indomethacin- and diclofenac-mediated leucotriene release in ASA-intolerant patients (n = 38) resulted in an increased sensitivity (from 50 to 72.7% in ASA-intolerant patients with predominantly airway-related symptoms and from 81 to 100% in ASA-intolerant patients with predominantly skin symptoms) compared with assays in which only ASA + C5a-mediated leucotriene release has been determined. Moreover, the specificity of the assay remained high (96.7% when analysing different NSAIDs compared with > 99% when analysing only ASA + C5a-mediated leucotriene release). CONCLUSION: In vitro stimulation with ASA + C5a leucocyte stimulation with other NSAIDs should be performed to achieve a higher sensitivity. This finding can be explained by the clinical observation of a high ratio of cross-reactivities between the mentioned NSAIDs.

Adult↗
PubMed1999

Continuous infusion of FVIII and FIX concentrates: in vitro analysis of clinically relevant parameters.

A high purity factor VIII/von Willebrand Factor (FVIII/vWF) concentrate (IMMUNATE [STIM plus]) (n = 6 batches), and a high purity factor IX (FIX) concentrate (IMMUNINE [STIM plus]) (n = 7 batches), were assessed in vitro for their applicability to continuous infusion. Parameters pertinent to continuous infusion were investigated and included stability, sterility and, in the case of FIX, the generation of potentially thrombogenic components. Four stationary or transportable mini infusion pumps, equipped with polyethylene, polypropylene or polyvinylchloride plastic components were used. The concentrates were reconstituted without extra filling volume and perfused at 12.5 mL h-1 and 1 mL h-1; sampling was carried out at the start of the experiment and for up to 48 h. The FVIII procoagulant activity (FVIII:C) was assayed by amidolytic, 1-stage and 2-stage assays; vWF was examined for ristocetin cofactor activity, antigen and multimers. The FIX coagulation activity (FIX:C) was determined by a 1-stage coagulation assay; thrombogenicity potential was assessed in vivo (Wessler stasis model in rabbits) and in vitro (FIXa and nonactivated thromboplastin time). Reconstituted concentrate incubated under the same conditions served as a control. Both concentrates remained sterile throughout the testing period. The perfused and control samples remained stable, retaining over 95% of activity for FVIII:C and over 90% for FIX:C for up to 48 h. Intermittent decrease of FVIII:C or FIX:C was not observed, suggesting no adsorption of FVIII or FIX onto plastic surfaces during either short or long-term exposure. No thrombogenic components were detected in the high purity FIX concentrate. Thus, under the in vitro conditions used, FVIII/vWF and FIX were found to be suitable for administration by continuous infusion.

Blood Coagulation Tests↗
PubMed1999

Microsurgical endonasal decompression in dysthyroid orbitopathy.

Diagnosis of thyroid eye disease can be established by its history, signs, symptoms, clinical and laboratory findings of an autoimmune thyroid disease. Therapy for this disease is limited to a few options, which should be administered depending on its stage and inflammatory activity. When medication and radiation therapy fail indications for decompression are: loss of visual acuity or visual field defects, increasing strabism and severe keratopathy due to eyelid retraction. Numerous surgical decompression techniques have been described in endocrine orbitopathy. We have adopted endonasal microsurgery, because this technique gives the freedom to work bimanually, ensures a stereomicoscopic view of the intranasal landmarks of orbital walls and allows simultaneous decompression of the medial and inferior orbital wall as well as a good relief of pressure at the orbital apex. Decompressions were performed on 27 orbits in 17 patients, via the endonasal microsurgical, 3 via external approach. The microscopic approach was entirely comparable with regard to reduction of proptosis with a mean improvement of 4.1 mm against a mean of 4.7 mm by external approach and a mean 0.2 of better visual acuity in both procedures. The microsurgical technique is considered superior to an external approach avoiding external scars, neural pains and reportedly less diplopia. Also, trauma to the nalolacrimal and nasofrontal ducts are avoided. The healing phase and the hospitalization time is shorter.

Adult↗
PubMed1999

Influence of bolus size on efficacy of postoperative patient-controlled analgesia with piritramide.

We have examined the influence of bolus size on efficacy, opioid consumption, side effects and patient satisfaction during i.v. patient-controlled analgesia (PCA) in 60 patients (ASA I-II, aged 32-82 yr) after abdominal surgery. Patients were allocated randomly, in a double-blind manner, to receive PCA with a bolus dose of either piritramide 0.75 mg or 1.5 mg (lockout 5 min) for postoperative pain control. Mean 24 h piritramide consumption differed significantly between groups (11.4 (SD 5.8) mg vs 22.5 (18.3) mg; P = 0.001). There were no significant differences in the number of applied bolus doses, pain scores, pain relief (VAS), sedation, nausea, pruritus and patient satisfaction. We conclude that a PCA regimen with a bolus dose of piritramide 0.75 mg and a lockout time of 5 min was effective in the treatment of postoperative pain, but did not reduce the occurrence of side effects.

Adult↗
PubMed1999

Acute normovolaemic haemodilution vs controlled hypotension for reducing the use of allogeneic blood in patients undergoing radical prostatectomy.

Blood loss in patients undergoing radical prostatectomy may be substantial. In a randomized, prospective study, we assessed two methods of reducing the need for allogeneic blood transfusion with regard to efficacy and costs. Sixty patients undergoing retropubic radical prostatectomy were allocated randomly to one of three groups. In group 1 (n = 20), acute normovolaemic haemodilution (ANH) was initiated after induction of anaesthesia; autologous blood 15 ml kg-1 was withdrawn and replaced by colloid solutions (gelatin) to maintain haemodynamic stability. In group 2 (n = 20), controlled hypotension was established using sodium nitroprusside (target mean arterial pressure (MAP) approximately 50 mm Hg). Group 3 (n = 20), without manipulations, served as a control group. Troponin T (TnT), a sensitive marker for myocardial ischaemia, and various coagulation variables were measured in the perioperative period. Packed red blood cells (PRBC) were given when haemoglobin concentration was less than 7 g dl-1. Cost calculations did not include hospital overhead costs or staff costs. In the ANH group, mean 1278 (SD 150) ml of autologous blood were withdrawn. Significantly more volume was infused in the ANH patients (gelatin 2450 (550) ml) than in the two other groups. Coagulation data (platelet count, activated partial thromboplastin time (aPTT), fibrinogen, antithrombin III (AT III), D-dimers) did not differ significantly between the three groups. The hypotension group had significantly lower blood loss (1260 (570) ml), whereas the ANH (1820 (680) ml) and control group (1920 (590) ml) did not differ significantly. Patients in the hypotension group needed significantly less PRBC (total 14 units; 75% of patients did not need PRBC) than the ANH (total 21 units; 55% of patients did not need PRBC) or control patients (total 28 units; 40% of patients did not need PRBC). Total costs were lowest in the hypotension group (41% less than in the control patients) (P < 0.05). We conclude that the use of hypotension during radical prostatectomy resulted in approximately 40% reduction in total transfusion costs. ANH was less effective and more costly than controlled hypotension.

Aged↗
PubMed1999

Eosinophilic cationic protein as a marker of nasal inflammation in patients with cystic fibrosis.

OBJECTIVES: Evaluation was made of eosinophilic cationic protein (ECP) in nasal secretion for measuring the degree of nasal inflammation and monitoring response to therapy in cystic fibrosis (CF) patients with chronic rhinosinusitis. Symptoms and findings in regard to ECP levels before and after treatment were described. STUDY DESIGN: Study was prospective, with 21 CF patients aged 4 to 19 years; 20 healthy volunteers served as controls. Collection of nasal secretion by a sponge was performed, and blood samples were obtained for serum. Cystic fibrosis (CF) patients were classified according to nasal symptoms and findings. METHODS: ECP was measured by fluoroimmunoassay. Age, sex, nasal symptoms, and endoscopic and histological findings were obtained, and examinations were conducted before and after treatment; recurrences were recorded. RESULTS: In CF patients with chronic nasal inflammation, increased nasal levels of ECP were detected when compared with asymptomatic CF patients or healthy nonatopic subjects. ECP concentrations were strongly related to the extent of nasal disease; patients with nasal polyps had higher levels than those without. Checked at 1 and 4 months after treatment, ECP levels declined with regression of symptoms, and in patients with exacerbation of nasal disease, ECP levels rose. CONCLUSIONS: According to our study, there is a relationship between levels of ECP in nasal secretions and the degrees of nasal inflammation. In addition, the measurement of ECP could be useful in monitoring nasal disease in CF patients.

Adolescent↗
PubMed1999

The phosphoenolpyruvate/phosphate translocator is required for phenolic metabolism, palisade cell development, and plastid-dependent nuclear gene expression.

The Arabidopsis chlorophyll a/b binding protein (CAB) gene underexpressed 1 (cue1) mutant underexpresses light-regulated nuclear genes encoding chloroplast-localized proteins. cue1 also exhibits mesophyll-specific chloroplast and cellular defects, resulting in reticulate leaves. Both the gene underexpression and the leaf cell morphology phenotypes are dependent on light intensity. In this study, we determine that CUE1 encodes the plastid inner envelope phosphoenolpyruvate/phosphate translocator (PPT) and define amino acid residues that are critical for translocator function. The biosynthesis of aromatics is compromised in cue1, and the reticulate phenotype can be rescued by feeding aromatic amino acids. Determining that CUE1 encodes PPT indicates the in vivo role of the translocator in metabolic partitioning and reveals a mesophyll cell-specific requirement for the translocator in Arabidopsis leaves. The nuclear gene expression defects in cue1 suggest that a light intensity-dependent interorganellar signal is modulated through metabolites dependent on a plastid supply of phosphoenolpyruvate.

Arabidopsis↗
PubMed1999

Efficacy of measures of hygiene in workers sensitised to acid anhydrides and the influence of selection bias on the results.

OBJECTIVES: Organic acid anhydrides are potential sensitisers and cause occupational airway diseases. In an intervention study the efficacy of measures of hygiene at the workplace and possible selection bias were investigated. METHODS: A first investigation with 110 workers exposed to hexahydrophthalic acid anhydride (HHPA) and methyltetrahydrophthalic acid anhydride (MTHPA) was carried out in July 1991. The results (skin prick test, specific serum IgE) showed that 20 people were sensitised, and in a challenge test the clinical relevance of the sensitisation was confirmed in six subjects. In December 1991, the hygiene conditions at the plant were improved. In November 1995 a second investigation of 84 people was performed (anamnesis, skin prick test, specific IgE, spirometry, and ambient and biological monitoring). The 27 people who had left the plant in the meantime were asked their reasons for leaving. RESULTS: The relative risk of people sensitised in 1991 of leaving the plant between 1991 and 1995 was 2.6 (95% confidence interval (95% CI) 1.4 to 4.9) compared with people without any sign of sensitisation. The percentage of people identified as sensitised in 1991, who were still working at the plant and came to the second investigation, was higher than for people without evidence of sensitisation (10/10 v 47/73; p < 0.05). In all the 10 sensitised people in 1991 the findings of the first investigation were confirmed in 1995. The rate of sensitisation in 1995 was 21%. None of the six people employed after 1991 showed evidence of sensitisation. Of the six people with clinically relevant sensitisation confirmed by a challenge test in 1991, five were still at their workplace. From 1991 they were only exposed to MTHPA at a reduced concentration (< 0.5-36 micrograms/m3 in 1995). All of them reported fewer symptoms than in 1991. No signs of bronchial obstruction were detected by spirometry at the workplace. CONCLUSIONS: In cross sectional studies there is a selection bias with a risk of underestimating the incidence of allergic diseases. The results further suggest that the improved hygiene conditions probably had a positive effect on the symptoms in sensitised people.

Adult↗
PubMed1999

Actin binding proteins that change extent and rate of actin monomer-polymer distribution by different mechanisms.

Actin binding proteins control actin assembly and disassembly by altering the critical concentration and by changing the kinetics of polymerization. All of these control mechanisms in some way or the other make use of the energy of hydrolysis of actin-bound ATP. Capping of barbed filament ends increases the critical concentration as long as ATP hydrolysis maintains a difference in the actin monomer binding constants of the two ends. A further increase in the critical concentration on adding a second cap, tropomodulin, to the other, pointed filament end also requires ATP hydrolysis as described by the model presented here. Changes in the critical concentration are amplified into much larger changes of the monomer pool by actin sequestering proteins, provided their actin binding equilibrium constants fall within a relatively narrow range around the values for the two critical concentrations of actin. Cofilin greatly speeds up treadmilling, which requires ATP hydroysis, by increasing the rate constant of depolymerization. Profilin increases the rate of elongation at the barbed filament end, coupled to a lowering of the critical concentration, only if ATP hydrolysis makes profilin binding to the barbed end independent of its binding constant for actin monomers.

Actin Depolymerizing Factors↗
PubMed1999

["Doctor" without being an M.D.--how do non-graduate MDs view medical dissertations?].

Both the ranking and the quality of medical dissertations have for some time been a controversial moot point. Previous studies showed that successful doctorate candidates still regard medical dissertations as a meaningful addition to medical studies. Studies on the views of the value have been placed on a medical dissertation by practising physicians who did not write a dissertation lacking to date. Using an anonymous questionnaire containing 16 questions we carried out a study of all the practising doctors in Mid-Franconia, Germany, who did not write a dissertation (n = 243). We asked about their intentions to write a dissertation, reasons for prematurely breaking off the dissertation and their views on the value of medical dissertations. Evaluation was carried out using descriptive statistics in the sense of an exploratory data analysis. The questionnaire was answered in a usable form by 140 physicians (return quote 58%). The average age of the participants was 44 years (33-89 years). The vast majority (89%) had attempted one or several dissertations, 32% still intended to write a dissertation. 59% regarded writing a dissertation alongside daily practice as very difficult of impossible. Private/family reasons were stated less often than deficits in planning, implementation and supervision for prematurely breaking off the dissertation. 65% of the practising physicians in Mid-Franconia who did not write a dissertation regard medical dissertation today as no longer relevant. 58% are of the opinion that the title "doctor" should be awarded automatically with the final exams. The majority of practising physicians asked had in the meantime given up their intention of writing a dissertation and today tend to disfavour medical dissertations. Nevertheless, one third of those who participated in the study still intend to write a dissertation. In view of this it should be discussed to what extent practising physicians interested in scientific questions can be helped to write a dissertation alongside their daily practice. In particular professors and lecturers of general medicine are called upon to make this possible.

Academic Dissertations as Topic↗
PubMed1999

[Medical rehabilitation in long-term disability].

UNLABELLED: Based on data from a prospective observational cohort study the following article attempts to answer two key questions of rehabilitation research in Germany: (1) What are the utilization rates of rehabilitation measures in patients with long-term work-incapacity due to low-back pain? (2) In this group of patients: does participation in rehabilitation programs correlate with return to work? Patients with long-term work-incapacity due to low-back pain report a severely impaired health status (measured by FFbH, SF-36, numeric rating scale for pain intensity) which calls for comprehensive medical treatment and rehabilitation. 40.5% of study patients received first time medical rehabilitation between three months and one year after the beginning of long-term work-incapacity, 20.5% between one year and two years after the beginning of long-term work-incapacity. These figures were not influenced by age. Considering the severity of impairment we judge these rates as being quite low. There was no positive correlation found between utilization of medical rehabilitation measures or any other medical treatment and return to work. A positive correlation was observed for utilization of first time medical rehabilitation between three months to one year after the beginning of long-term work-incapacity and functional capacity. This effect was demonstrable for patients 50 years of age or younger. CONCLUSIONS: (1) In our cohort utilization of medical rehabilitation measures in patients with low-back pain and long-term work-incapacity is quite low. This suggests a considerable amount of underutilization. (2) In order to avoid underutilization the process of accessing medical rehabilitation within the German health care system should be critically reviewed. (3) In the given context of high unemployment rates and the German early pensioning system the use of "return to work" as the main criterion to judge effectiveness of rehabilitation measures remains debatable.

Adult↗