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Biomedical subjects

M Langer

Publications and source records attributed to M Langer.

At least 163 records · Page 9Linked to original sources
PubMed1996

Short-term impact of the European Consensus Conference on the use of selective decontamination of the digestive tract with antibiotics in ICU patients.

Because it remained controversial, the use of selective digestive decontamination (SDD) in patients in the intensive care unit (ICU) was chosen as the topic of the first European Consensus Conference in Intensive Care Medicine (ECCICM) in December, 1991. The Consensus Bureau decided to assess the impact of this conference 2 years afterwards. For this purpose, a questionnaire was sent to the members of the European Society of Intensive Care Medicine, the Societé de Réanimation de Langue Française and the Societé Française d'Anesthesie et Réanimation before the conference. The recommendations following the conference discouraged the systematic use of SDD in ventilated patients and urged the monitoring of bacterial resistance and adapting antibiotics to epidemiology of the units. Two years after the conference, the same questionnaire was sent to those physicians who had responded to the first one. Eighteen percent used SDD for all ventilated patients and 17% remain users after 2 years. Among the occasional (32%) or continual (17%) users of SDD, the regimens used were mostly intravenous cefotaxime (60% of systemic antibiotics) and a topical combination of polymixin E, tobramycin, and amphotericin B (62% of overall topical combinations). The antibiotics used were unchanged after 2 years in almost all cases. In conclusion, the short-term impact of the Consensus Conference on SDD in ICU patients has been poor. This may be related to the continuing insufficiency of strong, definite data regarding the impact of this technique upon mortality and the theoretical risk of resistance to antibiotics, thus allowing physicians to stick to their policies until there is new evidence.

Anti-Bacterial Agents↗
PubMed1996

[Morphology of the carpal tunnel. Movement studies in patients with constriction symptoms and healthy probands using MR tomography].

The morphological correlation of the phenomenon of increased pressure in the carpal tunnel during wrist flexion and extension--as has been proved though measurements using wick-catheters--was studied in healthy subjects (n = 15) and symptomatic patients with carpal tunnel syndrome (n = 15). Our own measurements using magnetic resonance imaging (MRI) showed that there is a significant reproducible decrease in carpal tunnel diameter when the wrist is held in position of either flexion or extension. During flexion the diameter is decreased at the pisiformes and hamate level as well as it is lowered during extension at the pisiformes level. This might explain the rise in carpal tunnel pressure and thus the consecutive negative influence on the median nerve. Proximal swelling, distal flattening and increased signal intensity of the median nerve as well as the palmar bulging of the flexor retinaculum at the level of the hook of the hamate and at the level of the pisiformes were significantly higher in patients with carpal tunnel syndrome than in normal volunteers (from p < 0.05 to p < 0.001). In post-operative follow-up examinations of 13 patients with no clinic symptoms the distal flattening of the median nerve normalized in 94% within 3 months. The increased signal of the median nerve on T2-weighted images decreased postoperatively in 2/3 of the patients, whereas the motor latency of the median nerve recovered only in 39% of our patients who had 100% partial or complete clinical benefit. These findings imply that postoperative imaging may be helpful for evaluating the success or failure of surgical treatment.

Adult↗
PubMed1996

Metabolic response to radiation therapy in patients with cancer.

The effect of radiation therapy on substrate metabolism was evaluated in five patients with head and neck or lung cancer. Stable isotope tracer methodology was used to determine urea, amino acid, glucose, and lipid kinetics during postabsorptive conditions before initiation, near the midpoint (after receiving 2,672 +/- 36 rads), and at completion (after receiving 6,072 +/- 307 rad) of a 6- to 8-week course of radiation therapy. Nutritional status was maintained throughout the treatment period by providing supplemental enteral feedings as needed. Postabsorptive plasma insulin, catecholamine, and amino acid concentrations did not change during the course of treatment. Before radiation therapy was initiated, values for the plasma rate of appearance (Ra) of urea (3.35 +/- 0.33 micromol x kg(-1) x min(-1)), alpha-ketoisocaproate ([alpha-KIC] 2.16 +/- 0.19 micromol x kg(-1) x min(-1)), phenylalanine (0.59 +/- 0.052 micromol x kg(-1) x min(-1)), and glucose (10.56 +/- 1.31 micromol x kg(-1) x min(-1)) were in the normal range. However, glycerol and palmitate Ra values (3.11 +/- 0.30 and 2.01 +/- 0.33 micromol x kg(-1) x min(-1), respectively) were 25% higher than values observed previously in normal subjects. Substrate flux did not change during radiation therapy, and measurements obtained during the midpoint and at completion of treatment were similar to initial values. These results demonstrate that large doses of radiation therapy, administered over 6 to 8 weeks to the upper body, do not cause significant metabolic stress.

Amino Acids↗
PubMed1996

[Ultrasound and mammography follow-up of findings after breast saving operation and adjuvant irradiation].

AIM: The aim of our controlled retrospective study was to assess the diagnostic value of sonography for detection and characterisation of changes compared to mammography and palpation. METHOD: In 80 patients sonographic and clinical follow-up examinations were performed every 3 to 6 months, mammography examinations were performed every 6 to 12 months during the first 2 years after breast-preserving therapy (BPT) and irradiation. Extension, echogenicity, and configuration of lesions in sonography, and semiquantitiative description of diffuse or circumscribed changes in mammography were the basis of comparative follow-up observation. RESULTS: Postoperative seromas and haematomas, initially presenting echo-free or as hypoechoic lesions, showed an increase in echogenicity within 18 months after irradiation. Fat necrosis occurred in 9.5% of patients, lymph cysts developed in 4%, granuloma in 3%, recurrence of neoplasma in 1.6%. The diffuse loss of transparency in mammography that was associated with radiation therapy, showed a peak 6-12 months after irradiation. CONCLUSION: Sonography and sonographic guided puncture are mandatory tools to characterise circumscribed unclear lesions after breast-conserving therapy and irradiation in specialised centers. We recommend a 6-month interval for combined sonography, palpation, and mammography within the first 2 years after BPT and irradiation, because shorter control intervals did not result in relevant diagnostic advantages.

Adult↗
PubMed1996

[Endoluminal therapy of infrarenal abdominal aortic aneurysms: a new interventional technique].

PURPOSE: With a series of 31 transluminal stent-graft procedures, we assessed the feasibility and clinical effectiveness of a new stent-graft for the treatment of infrarenal abdominal aortic aneurysms (AAAs). METHODS: We treated the patients (male; mean age 71 years) with straight or bifurcated nitinol stents covered with woven dacron graft material for infrarenal eccentric saccular AAA (n = 4) or AAA involving the bifurcation and the common iliac arteries (n = 27). The 18-F delivery system was advanced via a surgical arteriotomy and the stent-graft was placed under fluoroscopic control. Follow-up period ranged from 8 days to 9 months. RESULTS: The implantation of the stent-grafts was technically successful in 30/31 cases. Procedure-related complications were acute hepatic failure due to gastric bleeding in a patient with liver cirrhosis, graft occlusion due to emboli originating from the left atrium (n = 1), macro-embolisation (n = 3), local haematoma (n = 1) and av-fistula (n = 1) requiring surgery. A post-implantation syndrome with leukocytosis and elevated C-reactive protein was observed in all patients. CONCLUSIONS: Endoluminal repair of infrarenal AAA with use of dacron covered nitinol stent-grafts is feasible, safe and clinically effective. However, careful long-term evaluation is necessary.

Aged↗
PubMed1996

Efficacy of intraoperative heat administration by ventilation with warm humidified gases and an oesophageal warming system.

We measured changes in body temperature in 12 hypothermic (mean aural temperature 34.4 (SD 1.0) degrees C) pigs during general anaesthesia with an open abdominal cavity and the effect of two warming systems: heating of inspired gases to 39 degrees C (intratracheal temperature) and oesophageal warming to 39 degrees C by a water perfused oesophageal heat exchanger. Each animal underwent both treatments and the control period in random sequence. Each condition was studied over 1 h. No additional protection against heat loss (drapes, blankets, i.v. fluids warming, etc.) was used. Anaesthesia, room temperature and relative humidity, amount and temperature of infusions and extension of exposed visceral surfaces were standardized. Mean decrease in body temperature was 1.0 (0.7) degree C (P < 0.005) without warming and 0.6 (0.2) degree C (P < 0.005) with heated inspired gases: this difference was not statistically significant. Oesophageal warming was very efficient as mean body temperature did not change significantly (-0.1 (0.2) degree C; ns).

Anesthesia, General↗
PubMed1996

A comparison of mixed integer programming and fast simulated annealing for optimizing beam weights in radiation therapy.

Two competing methods for assigning intensities to radiation treatment beams were tested. One method was derived from mixed integer programming and the other was based on simulated annealing. The methods faced a common objective and identical constraints. The goal was to maximize the minimum tumor dose while keeping the dose in required fractions of normal organ volumes below a threshold for damage. The minimum tumor doses of the two methods were compared when all the dose-volume constraints were satisfied. A mixed integer linear program gave a minimum tumor dose that was at least 1.8 Gy higher than that given by simulated annealing in 7 of 19 trials. The difference was > or = 5.4 Gy in 4 of 19 trials. In no case was the mixed integer solution one fraction size (1.8 Gy) worse than that of simulated annealing. The better solution provided by the mixed integer program allows tumor dose to increase without violating the dose-volume limits of normal tissues.

Abdominal Neoplasms↗
PubMed1996

A generic genetic algorithm for generating beam weights.

A genetic algorithm for generating beam weights is described. The algorithm improves an objective measure of the dose distribution while respecting dose volume constraints placed on critical structures. The algorithm was used to select beam weights for treatment of abdominal tumors. Weights were selected for up to 36 beams. Dose volume limits were placed on normal organs and a dose inhomogeneity limit was placed on tumor. Volumes were represented as sets of several hundred discrete points. The algorithm searched for the beam weights that would make the minimum tumor dose as high as the constraints would allow. The results were checked using dose volume histograms with standard sized grids. Nineteen trials were created using six patient cases by changing the required field margin or allowed beam position in each case. The sampling of points was sufficiently dense to yield solutions that strictly satisfied the constraints when the prescribed dose was renormalized by a factor of less than 6%. The genetic algorithm supplied solutions in 49 min on average, and in a maximum time of 87 min. The randomized search does not guarantee optimality, but high tumor doses were obtained. An example is shown for which the solution of the genetic algorithm gave a minimum tumor dose 7 Gy higher than the solution given by a simulated annealing algorithm under the same set of constraints. The genetic algorithm can be generalized to admit nonlinear functions of the beam intensities in the objective or in the constraints. These can include tumor control and normal tissue complication probabilities. The genetic algorithm is an attractive procedure for assigning beam weights in multifield plans. It improves the dose distribution while respecting specified rules for tissue tolerance.

Abdominal Neoplasms↗
PubMed1996

Abdominal aortic aneurysms: preliminary technical and clinical results with transfemoral placement of endovascular self-expanding stent-grafts.

PURPOSE: To evaluate treatment of infrarenal abdominal aortic aneurysm (AAA) with a new endoluminal stent-graft. MATERIALS AND METHODS: In 26 male patients, straight or bifurcated nitinol stents covered with woven Dacron graft material were implanted to treat eccentric saccular AAA (n = 3) or AAA involving the bifurcation and common iliac arteries (n = 23), with follow-up from 8 days to 8 1/2 months. RESULTS: Implantation was technically successful in all but one of the 26 (96%) patients (leak of the stent-graft for more than 3 months necessitated implantation of an additional covered stent). In seven of the 26 patients, minor residual perfusion persisted immediately after implantation, but complete thrombosis occurred within 7 days. Five procedure-related complications occurred: distal embolization (n = 2); local hematoma, which necessitated surgery (n = 1); acute hepatic failure due to gastric bleeding, in a patient with liver cirrhosis (n = 1); and stent-graft occlusion due to emboli originating from the left atrium (n = 1). CONCLUSION: Exclusion of AAA from circulation was feasible, safe, and clinically effective with the new stent-graft.

Aged↗
PubMed1996

HIV-related metabolic abnormalities in the brain: depiction with proton MR spectroscopy with short echo times.

PURPOSE: To analyze brain metabolite changes in human immunodeficiency virus (HIV)-positive neurologically asymptomatic patients and patients with acquired immunodeficiency syndrome (AIDS) dementia complex (ADC). MATERIALS AND METHODS: Twelve ADC patients, 11 HIV-positive asymptomatic patients, and 10 healthy control subjects underwent magnetic resonance (MR) imaging and proton MR spectroscopy with short echo times. Changes in N-acetyl aspartate (NAA), choline (Cho), myoinositol (MI), and creatine (Cr) were presented as ratios with Cr as the reference. RESULTS: Statistically significant (P < .05) differences were noted. In ADC patients, all with MR findings of brain atrophy and diffuse white matter disease, NA/Cr decreased (white matter, -31.8%; gray matter, -22.3%), MI/Cr increased (white matter, +42.5%; gray matter, +51.8%), and Cho/Cr increased (white matter, +20.6%; gray matter, +51.7%) compared with healthy control subjects. In HIV-positive asymptomatic patients, NA/Cr decreased slightly (white matter, -6.9%; gray matter, -5.1%), MI/Cr increased slightly (white matter, +13.7%; gray matter, +10.7%), and Cho/Cr did not change. CONCLUSION: ADC has a uniform pathologic metabolic pattern that affects NAA, MI, and Cho. Proton MR spectroscopy with short echo times helps detect early abnormalities in clinically asymptomatic patients.

AIDS Dementia Complex↗
PubMed1996

Multicentric reticulohistiocytosis. A report of 3 cases and review of literature.

Multicentric reticulohistiocytosis (MR) is a rare systemic disease of unknown cause. The disease is characterized by tissue infiltration of lipid-laden histiocytes and multinucleated giant cells. Destructive polyarthritis and skin lesions are the most common findings. The disease becomes apparent in adult life. We report on 3 patients and discuss the specific radiographic characteristics of bone and joint involvement. The radiologic feature is a bilateral, symmetric joint involvement with predilection for the interphalangeal and metacarpophalangeal joints. In all of our cases we found an early involvement of shoulder joints. Erosive arthritis begins at the margins of the joints, progressing to osseous defects and to severe joint destruction. In contrast to rheumatoid arthritis, periarticular osteoporosis and early joint space loss are absent in MR. In addition, significant erosions of distal interphalangeal joints are not common in rheumatoid arthritis.

Adult↗
PubMed1996

Pharmacokinetics of chlorprothixene after single intravenous and oral administration of three galenic preparations.

The absolute and relative bioavailability of chlorprothixene (CAS 113-59-7, Truxal) was studied in eight healthy male volunteers with three different formulations: solution, suspension and coated tablet. An intravenous infusion and an oral aqueous solution served as references. Single doses of 100 mg were administered in a randomized complete-block design with washout periods of two weeks. Serum concentrations of chlorprothixene were assayed using a high-performance liquid chromatographic method with electrochemical detection. After a 1-h infusion period the maximum serum concentration (Cmax) of chlorprothixene was 430 +/- 81 ng/ml (mean +/- S.D.) and subsequently decreased with a terminal elimination half-life (t1/2) of 25.8 +/- 13.6 h. The total serum clearance (Cl) and the apparent volume of distribution at steady state (Vss) were 867 +/- 167 ml/min and 1035 +/- 356 l, respectively. The profiles of the chlorprothixene serum concentration vs. time and the resulting pharmacokinetic parameters were similar for all orally administered formulations. The absolute oral bioavailability of 17% of the solution indicated a marked presystemic metabolism. The bioavailability of chlorprothixene relative to the oral solution was 56.4% with the coated tablet and 67.7% with the suspension. All pharmacokinetic parameters showed wide inter-subject variations, partly attributable to the respective formulation.

Administration, Oral↗
PubMed1996

Hoffa fracture--a radiologic diagnostic approach.

Hoffa fracture is a rare injury consisting of unicondylar tangential posterior fracture of the distal femur. On plain radiographs the fracture line is clearly seen. However, some fractures and musculotendinous injuries may display subtle features and may be difficult to detect even with optimal images. We explain the mechanism of injury, discuss the diagnostic work-up and the operative and nonoperative management.

Adult↗
PubMed1996

Magnetic resonance imaging (MRI) for detection of active sacroiliitis--a prospective study comparing conventional radiography, scintigraphy, and contrast enhanced MRI.

OBJECTIVE: Sacroiliitis is often difficult to diagnose in the absence of radiographic alterations. For the diagnosis of active sacroiliitis, plain radiography, scintigraphy, and contrast enhanced magnetic resonance imaging (MRI) were evaluated in a prospective study. METHODS: In 44 consecutive patients with complete clinical and laboratory evaluation, plain radiographs, quantitative sacroiliac (SI) scintigraphy, and MRI were performed to evaluate the contribution of these imaging techniques to the diagnosis of active sacroiliitis. Scintiscanning and MRI were done in 20 control subjects to define the normal range of imaging findings. We determined the sensitivity and specificity for each imaging method using a reference standard based on clinical symptoms of inflammatory low back pain with or without laboratory signs, and on clinical and radiographic followup during 1.5-2.5 years to confirm diagnosis. RESULTS: MRI was most sensitive (95%) and superior to quantitative SI scintigraphy (48%) or conventional radiography (19%) for the detection and confirmation of active sacroiliitis. For the assessment of inflammatory signs, MRI had higher specificity (100%) than scintigraphy (97%) or plain radiography (47%). At repeat MRI after 2-30 months, there was persistent pathologic signal intensity in the subchondral bone area despite clinically successful antiinflammatory drug therapy. CONCLUSION: For the assessment of active changes in the synovial portion and the subchondral bone marrow, contrast enhanced MRI is superior to quantitative SI scintigraphy or conventional radiography. MRI picks up an additional 75% of early cases not diagnosed by plain radiography. Scintigraphy is only of limited value. Persistent pathologic signal intensity in the subchondral bone marrow seems to be closely associated with previous inflammatory episodes, thus limiting specificity of MRI for active sacroiliitis. Based on our findings we suggest an algorithm for the evaluation of patients with suspected active sacroiliitis.

Adolescent↗