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Biomedical subjects

A Engel

Publications and source records attributed to A Engel.

358 records · Page 20Linked to original sources
PubMedDate not supplied

An analysis of interleukin-8, interleukin-6 and C-reactive protein serum concentrations to predict fever, gram-negative bacteremia and complicated infection in neutropenic cancer patients.

A prospective study was performed to assess the potential value of interleukin (IL)-8, IL-6, and C-reactive protein (CRP) serum levels to predict fever, gram-negative bacteremia and complicated infection in neutropenic patients with cancer. Serum samples were obtained three times a week during 208 neutropenic episodes following cytotoxic chemotherapy. Fever of any cause developed during 104 out of 191 evaluable episodes. Serum levels of neither cytokine nor CRP were predictive of fever within more than 24 h before its onset. Unlike CRP, both IL-6 and IL-8 serum levels were significantly different between microbiologically documented infections and unexplained fevers. The highest values of IL-6 and IL-8 were observed in episodes of gram-negative bacteremia. Using receiver-operating-characteristic curves, the analysis of cytokine levels measured around the onset of fever indicated that IL-8 is potentially useful for predicting gram-negative bacteremia, with a high negative predictive value of > 90% and a moderate positive predictive value of 50% (sensitivity, 70%; specificity, 91%). In patients with persistent fever, predictions of further clinical complications, defined as prolonged fever of more than 7 days' duration, pneumonia, shock and/or death due to infection, were best predicted by IL-6. With an IL-6 cutoff value of 250 pg/ml in samples obtained 8 to 32 h after onset of fever, the positive predictive value was 92%, the negative predictive value 91% (sensitivity, 85%; specificity, 95%). The positive predictive value of IL-6 in samples obtained another 24 h later from patients still febrile remained > 90%, but the negative predictive value dropped to 47%. In any of the analyses, the predictive values of CRP levels were poor and inferior to either cytokine. These findings may have clinical value in identifying subgroups of patients requiring different therapeutic approaches.

Adolescent↗
PubMedDate not supplied

Dacron graft aneurysm treated by endovascular stent-graft.

A 72-year old man who underwent aorto-bifemoral bypass with insertion of a Dacron graft 18 years previously presented with an aneurysm in the left limb of his graft. Angiography also demonstrated a bilateral occlusion of the popliteal arteries. Computed tomography (CT) angiography was performed and showed a localized dilation of 3 cm in the left limb of the graft, which had a diameter of 14 mm throughout. In view of the technical difficulties of a surgical procedure, an endovascular stent was considered. Through a left femoral arteriotomy, a stent graft was inserted and deployed in the left limb of the graft. This resulted in total exclusion of the Dacron graft aneurysm. To the best of our knowledge, this is the first report of such a procedure.

Aged↗
PubMedDate not supplied

Scanning tunneling and transmission electron microscopy on identical areas of biological specimens.

A methodology for tip and specimen-support manufacturing is described which allows for scanning tunneling microscopy (STM) and transmission electron microscopy (TEM) on identical areas of biological specimens, at comparable resolution. Topographs and dI/ds-maps were used to investigate tip-specimen interaction on native air-dried phage T4 polyheads where individual capsomeres and structural alterations upon repetitive scans have been observed at a tunnel current of 0.5 pA.

Microscopy, Electron, Scanning↗
PubMedDate not supplied

In vitro uptake 153gadolinium and gadolinium complexes by hyaline articular cartilage.

This in vitro study evaluated whether Gadolinium (Gd) penetrates into hyaline cartilage and would be incorporated into vital chondrocytes. Hyaline joint cartilage of rabbits was exposed to radioactive 153GdCl3 and to a radioactive 153Gd-DTPA-BSA-complex (DTPA, diethylene-triaminepentaacetic acid; BSA, bovine serum albumine). In addition an exchange experiment with radioactive 153GdCl3 versus Gd-DTPA-di-N-methylglucamine (Magnevist) was performed. Incorporation of 153GdCl3 into neuroblastoma cells, connective tissue cells and chondrocytes was tested. The results showed that the depth and extent of incorporation of Gd depends on the molecular mass and time of exposure. 153Gd-DTPA-BSA complexes exhibited an incorporation rate of maximal 11% +/- 2.8% up to the middle third of the cartilage within 24 h with almost no incorporation (2 +/- 1.9%) for the deep layer. The exchange experiment revealed no uptake of Gd for the deep layer. The maximal incorporation rate of 153GdCl3 into vital chondrocytes was 6.3%. These data indicate that under the condition of MR-arthrography, Gd-DTPA-di-N-methylglucamine will not be absorbed into the deep layers of hyaline cartilage and will not be incorporated into vital chondrocytes.

Animals↗
PubMedDate not supplied

Assembly of 2-D membrane protein crystals: dynamics, crystal order, and fidelity of structure analysis by electron microscopy.

Membrane protein reconstitution into two-dimensional (2-D) ordered arrays is described. The assembly of 2-D crystals may be modeled as a two-step process: the membrane protein is first integrated in the lipid bilayer and then crystallized by removal of excess detergent or lipid and/or by precipitating agents. Lipid-detergent, protein-detergent, and lipid-protein interactions are critical during the first step, while lipid-protein and protein-protein interactions dominate events in the second step. The evidence supporting this model results from quasielastic light scattering analyses and electron microscopy of different lipid-detergent systems and reconstitution experiments with Escherichia coli porin OmpF, Phormidium laminosum photosystem I reaction centers, and integral membrane proteins of mammalian lens fiber cells.

Animals↗
PubMedDate not supplied

Porin channel triplets merge into single outlets in Escherichia coli outer membranes.

Previous observations on the structural and functional properties of porin, the matrix protein of Escherichia coli, have indicated that the channel-forming trimers span the outer membranes of the bacterial cell, forming a molecular sieve. By using electron microscopy and image reconstruction, we demonstrate here that three channels on the outer surface of the cell merge into a single channel at the periplasmic face. Conductance measurements using conditions under which single activated triplets could be observed led us to conclude that the three individual consecutive closing steps reflect three channels within a single trimeric unit. Statistical analysis of conductance levels revealed that the first relaxation step is distinctly smaller than the two subsequent channel closings. This functional observation can be explained if the channels of porin trimers coalesce.

Bacterial Outer Membrane Proteins↗
PubMedDate not supplied

[Paget's coxarthrosis. Implantation of a modular tumor reconstruction system. Case report].

A male patient aged 69 years suffering from Paget-coxarthrosis with a large distension of the proximal femur was implanted a cementless tumor reconstruction system. The surgical procedure consisted of opening of the femoral shaft with a special drill, insertion of the prosthesis and its anchorage within the healthy distal bone. By this method we were able to save the femoral muscle insertion planes. Twenty-eight months postoperatively the patient is pain-free and very satisfied with the outcome. The X-rays show a good fit of the prosthesis. The Harris Hip Score is now 90.1 points as compared to 46.4 points preoperatively.

Aged↗
PubMedDate not supplied

[Muscle function of the thigh 10 years following a malignant bone tumor and implantation of a tumor prosthesis in the knee].

To objectify the muscle function of 5 patients ten years after implantation of a tumor endoprosthesis of the knee simultaneous muscle force and IEMG was recorded. The muscular activity in the operated leg was found to be reduced for the extension muscles (8-20%) and for the flexion muscles (28-52%) when comparing to the normal leg. Knee extension of the operated leg resulted from the function of the rectus femoris muscle. During normal exercise in daily life all patients were not handicapped und some of them did sport.

Adolescent↗
PubMedDate not supplied

[Surgical treatment of Osgood-Schlatter disease].

18 patients (20 knee joints) were operated for Osgood-Schlatter disease. 12 patients (14 knee joints) had a follow-up of 2.4 years (0.5-13.5) after operation. The informations of the other patients were taken from our clinical data. 1 month (0.5-24) after operation 13 patients (15 knee joints) were painfree. In 5 cases there were still complaints, but 3 of them were improved by operation. One patient, who was operated on both knees, had no change after operation. The failures are analysed and interpreted concerning their pathogenesis. With help of our results the different operation methods of the literature are discussed.

Adolescent↗
PubMedDate not supplied

[Functional evaluation of shoes for children based on gait analysis of children in the learning to walk stage].

RESEARCH QUESTION: Although gait patterns of children are well described in gait analysis studies for barefoot gait, loading patterns in gait with shoes have not been analysed compared to barefoot gait. METHODS: 30 children (age 1.8 to 4.8 years) were examined. Ground reaction forces were recorded using two series connected Kistler plates, taking the 3D coordinates and the time coordinate. The gait aspect was recorded using a video system. Three shoe types were tested against each other and against barefoot gait. RESULTS: 1399 gait cycles, 739 barefoot, 660 with shoes were usable for calculation. Statistic analyses comparing barefoot gait to gait with shoes showed: A significant increase in ground contact duration, a shifting of maximal load from the rear towards the midfoot area, a significant increased maximal load, a cushioning of the initial impact at primary ground contact. A comparison between the shoes showed no significant influence of a medial subtalar orthotic support. CONCLUSION: Shoes cause a significant change of loading patterns. But there are also significant differences between different shoe types. CLINICAL RELEVANCE: Shoes for children must provide a stabilisation for the hindfoot, and must not restrict motion in the areas of the ankle and the metatatrsophalangeal joints. The amount of load in the different gait phases must be considered for the construction of a dynamic shoe for children.

Biomechanical Phenomena↗
PubMedDate not supplied

MR contrast arthrography (MRA) in osteochondrosis dissecans.

Osteochondrosis dissecans (OCD) is a lesion that characteristically affects the articular cartilage and subchondral bone with the potential of fragmentation and separation. Exact assessment of cartilaginous and subchondral bony changes is mandatory for the planning of adequate treatment. Therefore, we examined 25 knees using spin echo (SE) and gradient echo (GE) sequences on a 1.5 T superconducting unit prior to and following intraarticular administration of 40 ml of a 2 mmol/L Gd-DTPA solution (MR arthrography). For evaluation (staging) a modified Clanton and DeLee scheme was employed. Verification by arthroscopy or arthrotomy was available in 24 cases. A correct diagnosis of OCD with regard to its type prior to intraarticular injection of Gd-DTPA was possible in 39.3% using T1-weighted SE sequences and in 57.4% on GE sequences. After intraarticular administration of Gd-DTPA, the rate of correct diagnoses improved to 92.9% on T1-weighted SE sequences and 100% on GE sequences. Magnetic resonance arthrography appears to be helpful for the exact assessment of the articular cartilage overlying OCD lesions as well as for the differentiation between partial and complete separation of cartilaginous or osteocartilaginous fragmentations.

Adolescent↗
PubMedDate not supplied

Bone marrow edema of the hip: MR findings after core decompression.

Magnetic resonance imaging is an extremely sensitive technique for evaluation of bone marrow changes at an early stage of avascular necrosis (AVN) of the hip. We therefore examined 11 painful hips whose clinical symptoms led us to suspect idiopathic AVN. The radiographs of all of these either were normal or demonstrated a minimal decrease in radiodensity. Magnetic resonance demonstrated diffuse signal loss of the bone marrow at short TR/TE images of the femoral head in all hips, with various extensions in the head, neck, and intertrochanteric area. These regions turned iso- to hyperintense on long TR/TE images compatible with bone marrow edema (BME). Focal abnormalities characteristic for AVN were not seen in any of the cases. Radionuclide studies performed in six cases were positive. All patients underwent core decompression treatment. Hydrostatic bone marrow pressure measurement and intraosseous venography were positive in five cases when measured. Histology available in eight cases confirmed the presence of BME. Furthermore, the bone changes corresponded to those of early AVN. Follow-up examinations after core decompression with MR showed normal signal intensity in all cases. Magnetic resonance represents a viable diagnostic tool for BME and can monitor the therapeutic success of core decompression. Whether BME of the femoral head constitutes a distinct transient syndrome or represents an early form of AVN is controversial at present. Our findings support those who believe that BME may represent an initial stage of idiopathic AVN.

Adult↗
PubMedDate not supplied

Postcontrast MR arthrography in assessment of cartilage lesions.

OBJECTIVE: Although MR has been proven effective in evaluating many components of the musculoskeletal system, including ligaments, fibrocartilage, muscle, and bone marrow, its role in the evaluation of articular cartilage remains controversial. Recent studies have demonstrated that intraarticular injection of Gd-DTPA [MR arthrography (MRA)] improves the detection of cartilage abnormalities in cadaveric specimens. The aim of this study was to determine the efficacy of MRA for the detection of naturally occurring cartilage lesions in a clinical population. MATERIALS AND METHODS: Sixty knees of 58 patients were studied with a three-dimensional (3D) T2*-weighted GE sequence (FISP) both before and after and a T1-weighted (T1W) SE sequence after the intraarticular injection of a 2 mmol/L Gd-DTPA solution. All knees subsequently underwent arthroscopy or arthrotomy. RESULTS: The MRA sequences performed significantly better (kappa = 0.85) than the routine FISP sequences (kappa = 0.39) in both the detection and the staging of cartilage abnormalities. The MRA FISP sequence (kappa = 0.91) performed slightly better than the MRA T1W sequence (kappa = 0.85), but there was no statistically significant difference between the two sequences. No complications from the intraarticular injection of contrast material occurred. CONCLUSION: Therefore, MRA appears to be an effective and safe method for the evaluation of articular cartilage abnormalities.

Adolescent↗
PubMedDate not supplied

Comparison of the TEMPO+ ear-level speech processor and the cis pro+ body-worn processor in adult MED-EL cochlear implant users.

A study was conducted to compare the new MED-EL TEMPO+ ear-level speech processor with the CIS PRO+ body-worn processor in the COMBI 40/COMBI 40+ implant system. Speech tests were performed in 46 experienced subjects in two test sessions approximately 4 weeks apart. Subjects were switched over from the CIS PRO+ to the TEMPO+ in the first session and used only the TEMPO+ in the time between the two sessions. Speech tests included monosyllabic word tests and sentence tests via the telephone. An adaptive noise method was used to adjust each subject's scores to approximately 50%. Additionally, subjects had to complete a questionnaire based on their 4 weeks of experience with the TEMPO+. The speech test results showed a statistically significant improvement in the monosyllabic word scores with the TEMPO+. In addition, in the second session, subjects showed a significant improvement when using the telephone with the TEMPO+, indicating some learning in this task. In the questionnaire, the vast majority of subjects found that the TEMPO+ allows equal or better speech understanding and rated the sound quality of the TEMPO+ higher. All these objective and subjective results indicate the superiority of the TEMPO+ and are mainly attributed to a new coding strategy called CIS+ and its implementation in the TEMPO+. In other words, based on the results of this study, it appears that after switching over from the CIS PRO+ to the TEMPO+, subjects are able to maintain or even improve their own speech understanding capability.

Adult↗
PubMedDate not supplied

Modulation of CD99/MIC2 expression of human AHTO-7 osteoblasts by carcinoma cell line-conditioned media.

BACKGROUND: Prostate cancer metastases induce a predominantly osteoblastic response in bone tissue, resulting in new bone formation and associated morbidity; however, the mechanisms of these tumor-host responses are not fully understood. MATERIALS AND METHODS: Supernatants of prostate (PC3, DU145, LNCaP), breast (BT20, ZR-75-1), colon (SW620, Colo 320DM), pancreatic (ASPC1, Capan-1), renal cell (ACHN) and hepatoma (HepG2) cell lines were tested for their capacity to modulate proliferation, activity of alkaline phosphatase (ALP) and CD99/MIC2 expression in AHTO-7 (large T antigen transfected human trabecular osteoblasts) cells in vitro. RESULTS: Osteoblastic stimulation is not restricted to prostate cancer derived conditioned media CM and high activity is found in CM from Capan-1, HepG2 and ACHN lines. Furthermore these CM down-regulate the expression of the CD99/MIC2 antigen in comparison to medium by AHTO-7 cells as detected by HBA-71 immunofluorescence, with the exception of prostate cancer-derived CM. Induction of the differentiation marker ALP was detected in response to CM derived from Capan-1, BT-20 and Colo320DM. Stimulation of the proliferation of AHTO-7 cells (105-138% of control), induction of ALP (1.17-5.29-fold) and down-regulation of CD99 (13.6-57.5%) exhibited no correlation. CM derived from PC3 and LNCaP metastatic prostate cancer cell lines specifically resulted in the retention/stimulation of the expression of CD99/MIC2 in AHTO-7 cells in contrast to all other cell lines tested. CONCLUSION: The CD99/MIC2 antigen, which is expressed on human osteoblasts and osteosarcoma cells, seems to constitute a new and independent response marker of osteoblasts in the triggering of osteoblastic reaction by prostate cancer cells.

12E7 Antigen↗