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Biomedical subjects

R Weiss

Publications and source records attributed to R Weiss.

568 records · Page 32Linked to original sources
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Noninvasive external recording of cardiac conduction system (His bundle) activity.

Successful and adequate external recording of the cardiac conduction system from the body's surface can be accomplished in 80 to 90 percent of subjects studied. High-gain amplification, signal averaging, and triggering with a conditioned QRS signal results in good recording reproducibility. Averaging of 128 consecutive cycles is adequate, but on occasion averaging of 256 cycles may yield better results. The patients's QRS signal triggers the transfer of signals, which are digitized and stored during the preceding P-R interval. Comparison of external recordings with direct invasive recordings in animals and patients shows good correlation between the major His bundle deflections. The advantages of the system developed include its mobility, triggering the QRS with pretrigger data processing, and instantaneous display on Polaroid photograph. Future research should concentrate on further miniaturization and simplification of the instrumentation, detailed experimental comparison between direct and external recordings for identification of deflections and their origin, further study of the recording lead system, and the most appropriate method of information display.

Animals↗
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[Enzyme, enzyme-histochemical and immunohistological studies in chronic erysipelas polyarthritis of swine].

The chronic Erysipelas-polyarthritis in pigs has been considered an animal model resembling human rheumatoid arthritis. Fifteen specifically pathogenfree (SPF) pigs 45 days old were experimentally infectec with strain T 28 of Erysipelothrix rhusiopathiae-bacteria. During the subsequent 32 weeks several enzymatic, immunohistological and microbiological parameters were monitored. Compared to 5 age and sex matched healthy controls the infected pigs showed increased activity of plasma acid phosphatase starting 4 weeks after the infection. Acid phosphatase activity was usually enhanced in synovial fluid of chronically ill animals. Histochemically increased activity of acid phosphatase, beta-glucuronidase and beta-acetylglucosaminidase was found in lining cells and fibroblasts of the synovial membrane of chronically diseased joints. Immunohistochemically Erysipelas-antigen was demonstrated in the synovial membrane even of those inflamed joints from which no living bacteria had been isolated. The microbiological and immunohistochemical results correlated positively with the enzymehistochemical data. The release of lysosomal enzymes from cells of the synovial membrane in chronically diseased joints due to the influence of Erysipelas-bacteria and the possible implications of persistent bacteria on the perpetuation of chronic Erysipelas-polyarthritis are discussed.

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Ultrasound-guided percutaneous fine needle aspiration biopsy of abdominal and retroperitoneal masses. Accuracy of cytology in the diagnosis of malignancy, cytologic tumor typing and use of antibodies to intermediate filaments in selected cases.

The reliability of ultrasound-guided fine needle aspiration biopsy (FNAB) in the detection of intraperitoneal and retroperitoneal malignancies was evaluated in 308 consecutive cases seen between 1979 and 1983. The prevalence of malignant neoplasms was 68.5%. The overall accuracy of FNAB diagnosis was 88.9%, with a sensitivity of 84.4% and a specificity of 98%. The predictive value of positive and negative results were 98.9% and 74.6%, respectively. Additionally, the cytologic results were statistically evaluated with respect to the different sites of the biopsied lesions (including pancreas, liver, kidneys and miscellaneous sites). The overall accuracy was highest for malignant lesions in the liver (96.4%) and in miscellaneous sites (89.5%). Reasons for false-negative results included incorrect areas sampled, limited material due to fibrosis or necrosis and cytologic misinterpretations. The accuracy of cytologic tumor typing with respect to histogenetic origin was 96.8%. Cytologic subclassification was performed with lower accuracy (82.5%), and exact determination of the site of the primary tumor from cytologic criteria alone was possible for 35.7% of carcinomas. In selected cases, routine cytologic examination was supplemented by intermediate filament typing using well-characterized antibodies against cytokeratin, vimentin, desmin and neurofilaments. Examples are shown in which use of this method clearly increased the accuracy of the diagnosis. Only two serious complications (bleeding) of fine-needle aspiration biopsy were encountered in this series.

Antibodies↗
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Diatrizoate contrast agents: 2-amino-5-acetamido-, and 3,5-diamino-2,4,6-triiodobenzoates.

We have examined the metabolic behavior of several triiodobenzoic acid derivatives because of the observed mutagenicity and cytotoxicity of 3-amino-5-acetamido-2,4,6-triiodobenzoate (I) and 3,5-diamino-2,4,6-triiodobenzoate (II). Measurements were facilitated using iodine-131 (131I)-labeled compounds. Drug retention in rabbits was monitored with a gamma camera. Metabolic products were studied by column and thin-layer chromatography. 3,5-Diacetamido-2,4,6-triiodobenzoate (diatrizoate) was partially deacetylated by liver microsomes to I and II. II was transformed in part to another substance whose structure remains undetermined. About 1% of nominal doses of I, II, and diatrizoate were retained for several days following intracardiac injection in rabbits. The rabbit did not appreciably acetylate I to diatrizoate and converted some of II to a urinary metabolite which was similar to that formed by liver microsomes. I was present in human urine following excretory urography with diatrizoate, but II was not detected. Manufacturers of diatrizoate should further reduce the level of free aromatic amines in preparations of diatrizoate. A method of doing so is reported.

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Mycobacterium avium infections in animals. Literature review.

Mycobacterium avium causes tuberculosis in chickens and other fowls but can also infect an extensive range of different animal species. The authors reviewed the available literature on this organism to show the importance of M avium infection.

Animals↗
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[Immunopathology and pathogenesis of chronic erysipelas polyarthritis of swine].

Several immuno-pathological aspects of polyarthritis following experimental infection with erysipelas in pigs were studied for two years. Aseptic and specifically pathogenfree animals were infected subcutaneously and intravenously-intraarticularly with living erysipeals bacteria (erysipelothrix rhusiopathiae) of serotype B. After an initial febrile phase a progressive polyarthritis and disco-spondylitis developed. Some animals also developed thrombo-endocarditis. Hypergammaglobulinemia and high titers of specific antibodies were observed during the whole experimental period. Antiglobulin factors, however, were not detected in the serum or the synovium. In some animals collagen antibodies were demonstrated in synovial tissue. Bacterial examination of the synovium showed that erysipelas bacteria were present in arthritic joints for months. Living erysipelas bacteria were isolated 24 months after the experimental infection from synovial tissue of two pigs. The polyarthritis was characterised by exudates rich in fibrin, villous proliferation, pannus formation, cartilage erosions, and peri-articular fibrosis. IgG and specific erysipelas antibodies were demonstrated in plasma cells from synovial tissue by immuno-histological methods. The findings emphasize the morphological resemblance of the erysipelas induced chronic polyarthritis in pigs to human rheumatoid arthritis.

Animals↗
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[The significance of coagulation disorders and the inflammatory reaction in an infectious model of rheumatoid arthritis. II. Inhibition trials with antirheumatic drugs in the inflammatory reaction phase of erysipelas polyarthritis in rats].

The arthritic activity in the initial phase and during manifestation of experimental erysipelas in rats, an animal model for human rheumatoid arthritis, was studied by plethysmometrical methods. The development of body weight and specific pathologic alterations peculiar to the model such as keratitis, thrombosis of the aorta and gangrene of the tip of the tail served as additional parameters. In the volumetric analysis it could be shown that the first arthritic swelling on both hind legs develops symmetrically up to day 6 post infection in rats with about 200 g of body weight-and in contrast-on the 2nd p.i. in younger animals with about 120 g. The first maximal paw volume was measured on day 9 p. i., the greatest decrease in body weight-a reduction of 25%-on day 10 p. i. In addition the reaction of the animal model following the application of steroid and non-steroid symptomatically as well as cytostatically acting antirheumatic drugs was tested. Daily treatment with acetylsalicylic acid, indomethacine or hydrocortisone provoked more or less significant inhibition of arthritic swelling in the paw. Only at the onset of arthritis acetylsalicylic acid was more effective than the other antiphlogistic drugs. No measurable increase of paw volume during cyclophosphamide treatment could be evaluated. None of the antirheumatics used had a positive effect on body weight developement. In hydrocortisone and also in cyclophosphamide treated rats a greater decrease was obtained than in the infected controls. No thrombosis developed after cytostasis with cyclophosphamide. The advantages of this systemic connective tissue disease with regard to its comparability with human rheumatoid arthritis and due to the course of its arthritic manifestation are discussed, together with the disadvantages specific to the model and the experimental conditions.

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T-cell acute lymphoblastic leukemia after renal transplantation in childhood.

PURPOSE: Lymphoproliferative disorders in solid organ recipients are usually of B-cell type and have rarely been described in childhood. This study describes the development of T-cell acute lymphoblastic leukemia (ALL) in a child occurring 6 years after renal transplantation. PATIENT: An 11-year-old boy had received a renal allograft from his father at 5 years of age. He was receiving imuran, prednisone, and cyclosporin A prophylaxis for graft rejection after transplant until T-cell ALL was diagnosed. Although an acute Epstein-Barr virus (EBV) infection was noted at the time of diagnosis, the EBV genome was not detected by Southern blot analysis and polymerase chain reaction (PCR) in the leukemic cells. RESULTS: A large mediastinal mass and malignant pleural effusion were noted at diagnosis. Leukemic cells of his bone marrow and pleural fluid expressed T-cell antigens with unique cytogenetic features, including add(1)(p36.1), del(11)(q14), and monosomy 7. EBV serology was consistent with a recent infection but EBV genome was not detected by Southern blot and PCR analysis in his leukemic cells. Human T-lymphotropic virus-I (HTLV-I) antibody titer was negative. He has been on chemotherapy for 9 months, maintaining his first remission. CONCLUSIONS: Malignancies developing after renal transplantations are usually lymphoproliferative disorders and of B-cell origin. In the majority of these patients, EBV plays an etiologic role. Although adult T-cell leukemia developing during immunosuppressive treatment in renal transplant recipients has been reported, T-cell leukemia after transplant in pediatric patients has not been reported to date. This case is unique in terms of the patient's age, the T-cell immunophenotype, the cytogenetic features, and the absence of an EBV genome within the leukemic cells despite an acute EBV infection before diagnosis.

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