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Biomedical subjects

A Marx

Publications and source records attributed to A Marx.

At least 235 records · Page 13Linked to original sources
PubMed1975

Biochemical basis of the serological cross-reactions between Brucella abortus and Yersinia enterocolitica serotype O:9.

A method based on the inhibition of agglutination is described that may be used for the differential serological diagnosis between B. abortus and Y. enterocolitica serotype O:9. An antigen with high immunological capacity was isolated from Brucella. This antigen inhibited both homologous and heterologous agglutination by Brucella antiserum, but only the heterologous agglutination by Yersinia antiserum. It proved to be constitued of a polysaccharide (N-acetylglucosamine, glucose, mannose and 2-keto-3-deoxyoctonic acid), a protein and a phosphoglycerid moiety. Lipid A was absent from the Brucella antigen. Incomplete polysaccharide synthesis of the Brucella antigen, with concomitant loss of serological specificity by the rough mutant has been described. Oligosaccharides containing N-acetylgalactosamine, glucose and galactose were isolated from the specific side chain of Yersinia lipopolysaccharide. Lipid A constituents were also identified in the latter.

Acetylglucosamine↗
PubMedDate not supplied

On the structure of microtubules, tau, and paired helical filaments.

Microtubules and their associated proteins form the basis of axonal transport; they are degraded during the neuronal degeneration in Alzheimer's disease. This article surveys recent results on the structure of microtubules, tau protein, and PHFs. Microtubules have been investigated by electron microscopy and image processing after labeling them with the head domain of the motor protein kinesin. This reveals the arrangement of tubulin subunits in microtubules and the shape of the tubulin-motor complex. Tau protein was studied by electron microscopy, solution X-ray scattering, and spectroscopic methods. It appears as an elongated molecule (about 35 nm) without recognizable secondary structure. Alzheimer PHFs were examined by FTIR and X-ray diffraction; they, too, show evidence for secondary structure such as beta sheets.

Aged↗
PubMedDate not supplied

Detection of SIV in rhesus monkey thymus stroma cell cultures.

To clarify the pathogenesis of SIV-induced thymus atrophy, the presence of SIV within thymus stromal cell cultures (epithelial cells, IDC, macrophages or fibroblasts) was investigated. The material studied consisted of 15 thymus specimens of rhesus macaques infected with SIVmac251 (2-4 months postinoculation). No viral antigen was detected, either in the cultures, by immunohistochemistry, or in cell culture supernatants, by ELISA (p17 antigen), and no viral RNA was detected by in situ hybridization. Only after coculture with the C8166 cell line, was virus detected in 2 out of 15 stroma cultures. The fact that the virus could only be detected after several passages of coculture with the C8166 cell line indicates that the virus exists in the thymus stroma cells in the form of proviral DNA. The infection of thymus stromal cells may contribute to the destruction of the thymus microenvironment and to the SIV-induced thymus atrophy.

Animals↗
PubMedDate not supplied

[Cup placement in hip replacement surgery -- A comparison of free-hand and computer assisted cup placement in total hip arthroplasty -- a multi-center study].

AIM: The purpose of the current study was to determine the accuracy of free hand and computer-assisted (CAS) cup placement. MATERIAL AND METHODS: Between June 1985 and August 2001, 105 free-hand and from March to November 1999 80 total hip arthroplasties under computer assistance were implanted in the above mentioned centers. To determine the accuracy of the cups, the inclination and anteversion angles were measured. In all cases the cup position was measured with a CT-investigation of the pelvis. Statistical analysis was performed with the F-test. RESULTS: With regard to the inclination and anteversion angles the variability of the cup position was significantly higher in the group of free hand implanted cups. In the CAS group we could not find any "extreme" positions. CONCLUSION: Using computer-assisted surgery a significantly higher reproducible cup position can be obtained. Long time survey may present a lowering of the rate of early and late complications caused by better prostheses alignment in the follow up.

Adult↗
PubMedDate not supplied

[Influence of the x-ray technique on evaluation of cup anteversion after total hip arthroplasty].

AIM: Total hip arthroplasty (THA) is a standard procedure in orthopaedic surgery. Planar radiography of the implant is routinely performed to ensure that the operation has achieved the desired result. This study investigates the influence of varying the X-ray beam on the analysis of the radiograph. METHOD: Twenty-three patients were analysed after implantation of a total hip replacement. Besides a CT scan of the pelvis, symphysis- and hip-centred radiographs were available. The cup anteversion was calculated using two published algorithms. The CT-based data were the gold standard. RESULTS: Our study revealed a significant major error in the analysis of the symphysis-centred radiographs when compared with the hip-centered radiographs. Widmer's algorithm showed a significant superiority over Pradhan's formula. CONCLUSION: The best approximation of the anteversion angle was achieved using Widmer's technique by centering the X-ray beam onto the hip.

Acetabulum↗
PubMedDate not supplied

[Heparin-induced thrombocytopenia after elective hip joint replacement with postoperative prevention of thromboembolism with low-molecular-weight heparin].

BACKGROUND: Heparin-induced thrombocytopenia (HIT) is a severe side effect of the prophylaxis of venous thromboembolism with unfractionated heparin. The aim of the present study is to gain more information on the incidence of HIT during prophylaxis of venous thromboembolism with low-molecular-weight heparin in elective hip surgery. METHODS: 586 consecutive patients were included into the prospective study, who were admitted to hospital for elective hip replacement. The incidence of thrombocytopenia, clinically manifest venous thromboembolism and of the heparin-induced IgG antibodies were analysed during prophylaxis with low molecular-weight heparin. Patients received once daily subcutaneously low molecular-weight heparin for a mean of 28 days postoperatively. Platelet counts and clinical examinations for the presence of venous thromboembolism were done at days 0, 2, 7 (+/- 1) and 12 (+/- 2). Heparin-induced IgG antibodies were determined before and after a 12 (+/- 2) days prophylaxis with low molecular-weight heparin in 265 of 586 patients randomly. Patients were reexamined for thromboembolic complications after 3 and 6 months. The clinical suspicion of thromboembolic complication was documented objectively. RESULTS: None of the patients developed a decrease of platelets of < 50% of the initial value. Ten of 265 patients had elevated IgG antibodies against heparin/platelet factor 4 before prophylaxis (3.8%). After the 12 (+/- 2) days prophylaxis 13 of 265 patients had elevated IgG antibodies (4.9%). C14 serotonin assay was positive in 0 of 10 patients before treatment and in 3 of 19 patients at day 12 (+/- 2). Ten patients developed venous thromboembolism postoperatively (8 x deep venous thrombosis, 2 x pulmonary embolism, no fatal embolism). Only 1/19 patients with elevated antiheparin IgG titres developed venous thromboembolism. The C14 serotonin assay was negative in this patient. Two patients died in the postoperative phase due to underlying cardiovascular diseases. CONCLUSIONS: In patients with elective hip replacement prophylaxis of venous thromboembolism with low molecular-weight heparin was associated with a very low incidence of HIT, and hence screening for HIT antibodies is not required.

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