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Biomedical subjects

A Vogt

Publications and source records attributed to A Vogt.

At least 181 records · Page 10Linked to original sources
PubMed1981

[Left ventricular volumes by cross-sectional echocardiography in the dog: a comparison with biplane angiocardiography (author's transl)].

Using apical long axis and precordial short axis views, left ventricular end-diastolic and end-systolic volumes and ejection fraction were determined by cross-sectional echocardiography and compared with biplane angiocardiography. 10 anesthetized, closed chest dogs were first studied in the control state. Inferior vena cava was occluded by a balloon-inflated catheter, measurements were repeated. Descending aorta was blocked, with measurements retaken. Finally 8 dogs were studied after left coronary artery occlusion. For enddiastolic volumes correlation coefficients were 0.89, 0.93, 0.89, and 0.90 respectively (n = 10, 10, 10, 8; p less than 0.01). End-systolic volumes correlated with r 0.94, 0.92, 0.83, 0.92 (p less than 0.01). Left ventricular volumes were systematically underestimated by echocardiography (p less than 0.05). Ejection fraction corresponded less favourably, overall r was 0.85 (n = 38; p less than 0.01). Thus, cross-sectional echocardiography appears suitable for quantifying left ventricular volumes, less ejection fraction in the dog, during acute interventions as well as in the presence of regional dysfunction.

Angiocardiography↗
PubMed1980

Collinearity-preserving functions between Desarguesian planes.

Using concepts from valuation theory, we obtain a characterization of all collinearity-preserving functions from one affine or projective Desarguesian plane into another. The case in which the planes are projective and the range contains a quadrangle has been treated previously in the literature. Our results permit one or both planes to be affine and include cases in which the range contains a triangle but no quadrangle. A key theorem is that, with the exception of certain embeddings defined on planes of order 2 and 3, every collinearity-preserving function from one affine Desarguesian plane into another can be extended to a collinearity-preserving function between enveloping projective planes.

Journal Article↗
PubMed1980

Anionic binding sites in the glomerular basement membrane: possible role in the pathogenesis of immune complex glomerulonephritis.

This paper details the ways in which the anionic sites of the GBM could be involved in immune complex deposition. Experiments were performed with chemically cationised proteins to test the hypotheses proposed. The most detailed investigations were concerned with the role of basic (cationic) antigen as a planted antigen, leading to in situ immune complex formation. A model was developed where it was possible to induce marked proteinuria following a single injection of small quantities of cationised human IgG or ferritin.

Animals↗
PubMed1980

An approach to postembedding staining of protein (immunoglobulin) antigen embedded in plastic: prerequisites and limitations.

A method is described for performing postembedding staining of protein (immunoglobulin) antigen embedded in styrene-methacrylate resin. Fixation of specimens in a combination of 4% paraformaldehyde and 0.2% picric acid and washing in buffer containing 7% sucrose, followed by abrupt dehydration with absolute acetone in the cold preserved the antigenicity, although in a masked form. The masked antigenicity could be reexposed by treatment with nonspecific protease. Staining with fluorescent-, peroxidase-, or ferritin-labeled antibodies on semi- and ultrathin sections resulted in specific localization of the antigen. We applied this technique to the localization of rabbit immunoglobulin in specimens of renal tissue obtained from rats with anti-glomerular basement membrane nephritis; we also localized human IgG in a renal biopsy specimen. The prerequisites for recovery of antigenicity are such that preservation of tissue structure at the light microscopic level is good, but relatively poor at the electron microscopic level.

Animals↗
PubMed1980

'In situ' immune complex nephritis and basic proteins.

This investigation was designed to clarify the potential role of basic antigens in immune complex nephritis. The GBM is negatively charged and binds cationic substances. We studied 1) whether chemically cationised proteins can bind to the GBM, act as planted antigen, and induce 'in situ' immune complex formation or 2) if a pre-formed cationic antigen antibody complex can localise in the GBM. Results obtained with 5 chemically cationised proteins support the first possibility.

Animals↗
PubMed1980

A model of in situ immune complex glomerulonephritis in the rat employing cationized ferritin.

In the model described here the ability of cationized (basic) ferritin to bind to the glomerular basement membrane and act as a planted antigen was exploited. This planted antigen was accessible to circulating antibody resulting in in situ immune complex formation. Perfusion of cationized ferritin (isoelectric point greater than 9.5) directly into the renal arteries, followed by intravenous injection of anti-ferritin antibody resulted in induction of glomerulonephritis with heavy proteinuria lasting for about 3 weeks. Fine granular deposition of antigen, antibody and rat C3 along the glomerular capillary walls was seen by immunofluorescence. Electron microscopy revealed the presence of subepithelial deposits containing ferritin; the foot processes were fused. This demonstrates the potential role of basic antigens in the pathogenesis of in situ immune complex glomerulonephritis.

Animals↗
PubMed1980

Hemodynamic effects of the new vasodilator drug Bay k 5552 in man.

The hemodynamic effects of the new vasodilator drug isobutyl methyl 1,4-dihydro-2,6-dimethyl-4-(2-nitrophenyl)-3,5-pyridinecarboxylate (nisoldipine, Bay k 5552) were observed in 9 patients undergoing cardiac catheterization. The drug was administered i.v. in a dose of 1.5 microgram/kg body weight. Within 1 min after injection aortic pressure decreased by 11.5 +/- 6.4%, cardiac index increased by 23.1 +/- 13.5%, and heart rate accelerated by 18.3 +/- 10.1% of control value. Calculated total peripheral resistance was reduced by 28.2 +/- 10.1%. The whole low pressure system as well as the dp/dt max remained unaffected by the drug. The stroke volume index showed a slight and insignificant increase. Thus, Bay k 5552 represents a fast and power fully acting vasodilating substance with its actions being restricted mainly to the peripheral vasculature.

Adult↗
PubMed1979

Immunohistological staining of antigens on semithin sections of specimens embedded in plastic (GMA-Quetol 523).

Glycol methacrylate-Quetol 523, introduced by Kushida (1977) for combined light and electronmicroscopy studies at low magnification, also permits application of immunofluorescence methods to semithin sections. To recover the antigenicity of proteins fixed with formaldehyde, abrupt dehydration before embedding and subsequent treatment of the semithin sections with protease were essential. Post-staining with suitable histological stains allows exact correlation of antigen localization with tissue structure.

Acrylic Resins↗
PubMed1979

The isolation of an optimal small size immunoferritin conjugate fraction.

A procedure is described for preparing immunoferritin conjugates consisting of one antibody molecule attached to one ferritin molecule. Results obtained with such a reagent faithfully reflect the true distribution of antigenic determinants, and allow more accurate quantification.

Antibodies, Fungal↗
PubMed1979

Immuno-electron microscopic localization of lipopolysaccharide antigens on ultrathin sections of Salmonella typhimurium.

Lipopolysaccharide antigens were demonstrated on ultrathin sections of styrene-embedded Salmonella typhimurium by direct postembedding staining with ferritin-labeled antibodies. The antigenicity, partially masked in the embedding process, could be satisfactorily recovered by treatment of ultrathin sections with nonspecific protease. As judged from the reaction site of the ferritin-labeled antibodies, the lipopolysaccharides were localized in two zones. The broader zone of densely distributed ferritin molecules was superimposed over the whole outer cellwall, and a smaller zone revealing antigenicity was found over the cell membrane, which strongly supports the concept that the latter is the site of synthesis of lipopolysaccharides. The well-defined labeled areas between these two antigenic zones may be the routes whereby the synthesized polysaccharide molecules reach the cell wall.

Antigen-Antibody Reactions↗
PubMed1979

Lack of fibrin formation in exercise-induced activation of coagulation.

Strenuous physical exercise leads to a significant shortening of blood clotting in various test systems. Such short times are also characteristic of those observed in sedentary patients with thrombosis or disseminated intravascular coagulation, and of those observed in experimental animals after thrombin infusion. The patients exhibit an increase in circulating fibrinopeptide A, which is attributed to thrombin action on circulating fibrinogen, and to an increase of fibrinogen degradation products, which is thought to indicate reactive fibrinolysis. To check whether physical exercise leads to fibrinemia, 10 healthy male volunteers were subjected to strenuous exercise on a bicycle ergometer. Blood samples were taken immediately before and on completion of the exercise period. Despite a significant shortening of the activated partial thromboplastin time, the thrombin time, and the Reptilase time, no increase of fibrinopeptide A could be demonstrated and the ethanol gelation test remained consistently negative. Simultaneously, the euglobulin lysis time was significantly shortened, whereas the fibrin(ogen) degradation products did not increase. The results indicate that the shortening of the coagulation times associated with physical exercise must be explained by mechanisms other than thrombin-mediated conversion of fibrinogen to fibrin.

Adult↗
PubMed1979

Autoantibody specific for the glomerular mesangium and Bowman's capsule in man.

Investigation of serum from a nominally healthy subject revealed an unusual autoantibody with specificity for the glomerular mesangium and Bowman's capsule. Immunofluorescence studies on rodent kidney sections revealed typical mesangial fluorescence and intense linear staining of Bowman's capsule. The antibody was organ, but not species, specific and did not correspond to any previously described antibody with anti-mesangial activity (e.g. anti-actomyosin or anti-fibronectin). Intravenous injection in mice resulted in heavy mesangial deposition of antibody within one hour, the antibody disappeared within 2--4 weeks, and no urinary abnormalities were seen. Retrospective analysis of clinical data revealed a history of chronic hepatitis and possible drug abuse, but no evidence for impaired renal function at any timepoint. To our knowledge this is the first report of specific anti-mesangial antibody in man, the pathogenetic relevance remains unclear.

Animals↗
PubMed1979

Pathogenetic role of mesangial immune deposits.

This investigation was designed to clarify the pathogenetic role of immune complexes within the mesangium. We administered a ferritin-protein antigen to rats which localised and persisted within the mesangium. Subsequently administration of anti-ferritin antibody resulted in binding of antibody to the mesangially located antigen. The effect of this immune complex formed in situ was studied in long-term experiments and no evidence of glomerular impairment was seen. These results lend support to the view that an immunological process, confined to the mesangium, may not necessarily compromise renal function.

Animals↗
PubMed1979

Comparison of the handling of ferritin and ferritin-protein conjugates by the glomerular mesangium: kinetic studies in the rat.

Kinetic studies on the uptake and elimination of ferritin and ferritin-protein conjugates in the rat glomerular mesangium are reported. Ferritin was prepared from horse spleens and conjugates were prepared using either human IgG or albumin. The degree of mesangial uptake was dose dependent and a competitive effect with the reticuloendothelial system was observed. Maximal mesangial fluorescence occurred at a lower dosage with conjugate than with native ferritin. In addition, conjugate persisted for months within the mesangium as compared to a matter of days in the case of ferritin alone. The disappearance of native ferritin from the mesangium paralleled that seen in the circulation. Conjugate, however, disappeared far more rapidly from the circulation than from the mesangium. At a point in time when the mesangium still contained conjugate but the blood was negative, rabbit antiserum to ferritin was injected and was observed to deposit in the mesangium. This demonstrated the accessibility of mesangially sequestered antigen to circulating antibody. This system provides a model for long term studies on the effect of immune reactions occurring in the mesangium.

Animals↗
PubMed1979

Excitation of afferent fibres in the cardiac sympathetic nerves induced by coronary occlusion and injection of bradykinin. The influence of acetylsalicylic acid and dipyron.

Afferent impulse activity was recorded in single fibres of the inferior cardiac sympathetic nerve of the cat. When the descending branch of the left coronary artery was ligated for 60 sec an enhancement of afferent impulses was recorded. Elevations in discharge frequency were also induced by injecting bradykinin, epinephrine, and isoprenaline or by general hypoxia due to interruption of the artificial ventilation. When these procedures were after pretreatment with the analgesic agents, acetylsalicylic acid or dipyron a reduction in spike discharge was observed only with bradykinin after application of acetylsalicylic acid. No influence of these pretreatments on the effects of coronary occlusion, general hypoxia and injection of epinephrine and isoprenaline could be observed. These results suggest that bradykinin does not predominate as mediator substance in eliciting ischemic heart pain.

Aminopyrine↗
PubMed1978

[Missing thrombinemia in the so-called hypercoagulability following physical exertion (proceedings)].

A common topic of discussion for many years has been whether stress induces hypercoagulability and/or hyperfibrinolysis. Ten healthy volunteers were subjected to strenuous physical effort on a bicycle ergometer. Blood samples were collected 10 min before and immediately after exercise. The well-known activation of blood coagulation was demonstrated by significant shortening of the activated partial thromboplastin time, thrombin and reptilase times. However, no fibrinopeptide A (FPA) was generated, nor did the ethanol gelatin test turn positive. A significant shortening of the euglobulin lysis time was indicative of fibrinolysis but no fibrin(ogen) degradation products (FDP) could be detected. These results show that the so-called hypercoagulability is not accompanied by thrombin-mediated release of fibrinopeptide A, and suggest that the activation of coagulation does not involve fibrinogen to fibrin conversion.

Adult↗
PubMed1978

Separation of anti-dinitrophenyl antibodies according to affinity by fractionated elution from immunoadsorbent using thiocyanate.

The possibility of fractionating anti-DNP-antibodies according to their affinity by successive elution from a DNP-immunoadsorbent with increasing concentrations of thiocyanate (KSCN) was investigated. Using KSCN at molarities of 0.5 M, 2.0 M and 3.0 M in a stepwise elution procedure, the mean affinity of the eluted antibody fractions was found to increase with increasing molarity of the eluent. The method described is a simple, reliable means of separating antibodies on an affinity basis which is of special value in systems where haptens are not available.

Animals↗