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Biomedical subjects

A Vogt

Publications and source records attributed to A Vogt.

At least 19 recordsLinked to original sources
PubMed1992

[Mitral insufficiency after percutaneous balloon valvuloplasty in mitral stenosis. Incidence and progression].

Percutaneous balloon valvoplasty of the mitral valve was performed in 126 patients (24 men, 102 women; mean age 55.0 +/- 12.1 years) with mitral stenosis. The mean transmitral valve gradient fell from 12.4 +/- 6.1 to 6.0 +/- 3.2 mmHg, while the valve opening area increased from 1.0 +/- 0.2 to 1.55 +/- 0.3 cm2. After percutaneous balloon valvoplasty 36 patients still had no mitral regurgitation, while the grade of mitral regurgitation remained the same in 47 (grade I: n = 35; grade I: n = 12). Mitral regurgitation, previously not present, occurred in 25 patients, but was severe in only three (grade III: n = 1; grade IV: n = 2). Previously present mitral regurgitation increased in 18 of 65 patients, in four to grade III, in one to grade IV. In three patients acute grade IV mitral regurgitation resulted from a tear in a leaflet of a fibrotic valve which was not or only slightly calcified, requiring emergency surgery. Followup observations over 16.9 (1-60) months showed no change in most patients, but three developed mitral regurgitation. The latter underwent elective surgery, as did one patient with acute mitral regurgitation. Thus a total of seven patients (5.6%) required surgery for mitral regurgitation after percutaneous balloon valvoplasty.

Adolescent↗
PubMed1992

Improved thrombolysis in acute myocardial infarction with front-loaded administration of alteplase: results of the rt-PA-APSAC patency study (TAPS)

Thrombolysis with recombinant tissue-type plasminogen activator (rt-PA) and anisoylated plasminogen streptokinase activator (APSAC) in myocardial infarction has been proved to reduce mortality. A new front-loaded infusion regimen of 100 mg of rt-PA with an initial bolus dose of 15 mg followed by an infusion of 50 mg over 30 min and 35 mg over 60 min has been reported to yield higher patency rates than those achieved with standard regimens of thrombolytic treatment. The effects of this front-loaded administration of rt-PA versus those obtained with APSAC on early patency and reocclusion of infarct-related coronary arteries were investigated in a randomized multicenter trial in 421 patients with acute myocardial infarction. Coronary angiography 90 min after the start of treatment revealed a patent infarct-related artery (Thrombolysis in Myocardial Infarction [TIMI] grade 2 or 3) in 84.4% of 199 patients given rt-PA versus 70.3% of 202 patients given APSAC (p = 0.0007). Early reocclusion within 24 to 48 h was documented in 10.3% of 174 patients given rt-PA versus 2.5% of 163 patients given APSAC. Late reocclusion within 21 days was observed in 2.6% of 152 patients given rt-PA versus 6.3% of 159 patients given APSAC. There were 5 in-hospital deaths (2.4%) in the rt-PA group and 17 deaths (8.1%) in the APSAC group (p = 0.0095). The reinfarction rate was 3.8% and 4.8%, respectively. Peak serum creatine kinase and left ventricular ejection fraction at follow-up angiography were essentially identical in both treatment groups. There were more bleeding complications after APSAC (45% vs. 31%, p = 0.0019).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Purification and characterization of a tryptic peptide of Borrelia burgdorferi flagellin, which reduces cross-reactivity in immunoblots and ELISA.

In man the early immune response in Lyme disease is primarily directed against the endoflagellin antigen. Isolated flagellar protein of Borrelia burgdorferi suggests itself as a suitable test antigen. However, cross-reactivity between flagellins of B. burgdorferi, Escherichia coli, Bacillus subtilis, Proteus mirabilis and Salmonella typhimurium was demonstrated by immunoblotting and ELISA with polyclonal rabbit-hyperimmune-sera. Tryptic cleavage of recombinant B. burgdorferi 41 kDa flagellin, expressed in E. coli, produced a peptide fragment which was recognized exclusively by antisera to Borrelia species. This peptide was designated as the 14 kDa fragment due to its migratory behaviour in SDS-PAGE. The fragment is part of the variable region of the flagellin, as proven by amino acid sequencing. The flagellin peptide was employed as an antigen in ELISA and immunoblot assays, testing the polyclonal sera mentioned above. The specificity was superior to that obtained with the intact recombinant flagellin.

Amino Acid Sequence↗
PubMed1992

Glomerular immune deposits in murine lupus models may contain histones.

Two types of lupus mice, NZB/NZW F1 female hybrids and mice with graft-versus-host disease (GVHD), were studied. Histones H3 and H2A were detected by immunofluorescence in glomeruli of 22/22 proteinuric GVHD and 8/12 proteinuric NZB/W F1 female mice; in non-proteinuric animals, 3/5 GVHD and 2/27 NZB/W F1 female were positive. Using antibodies to histone peptides it was shown that mainly the N-terminal regions of histones H3 and H2A were exposed in glomerular deposits. Western blot analysis revealed antibodies to histone subfractions in sera of 33/34 lupus mice that developed proteinuria. This study provides evidence that histones are involved in the pathogenesis of lupus nephritis.

Animals↗
PubMed1991

[Percutaneous balloon valvuloplasty in mitral stenosis].

Between June 1986 and June 1989, percutaneous balloon valvuloplasty (PBV), using the transseptal, single-balloon technique, was performed in 50 consecutive patients (38 women and 12 men; mean age 54 +/- 14 years) with mitral stenosis. The procedure was technically successful in 48 patients (in one patient the atrial septum could not be crossed, in the other cardiac tamponade occurred). The mean diastolic gradient was decreased from 12.5 +/- 6.6 to 6.1 +/- 3.1 mmHg, mean pulmonary artery pressure (PAP) reduced from 29 +/- 12 to 22 +/- 6 mmHg, and valve opening area increased from 1.0 +/- 0.25 to 1.6 +/- 0.4 cm2. Redilatation had to be undertaken in four patients because of restenosis. Commissurotomy had to be performed in one patient, valve replacement in nine (restenosis in 4, poor primary results in 3, increase in regurgitation in 2). One patient died of a noncardiac cause. Follow-up observations for an average of 14 (3-36) months indicated in 30 of the remaining 33 patients without additional intervention a stable clinical improvement of at least one class (NYHA classification), as well as stable haemodynamic findings (gradient: 6.0 +/- 2.7 mmHg, valve opening area 1.5 +/- 0.3 cm, PAP 23 +/- 7 mmHg. Thus PBV achieved, at least in the medium term, clinical improvement in about two thirds of patients, and an operation was avoided.

Adolescent↗
PubMed1991

Surface charge distribution is a determinant of antigen deposition in the renal glomerulus: studies employing 'charge-hybrid' molecules.

The deposition of antigens and immune complexes (IC) in the renal glomerulus is charge-dependent. The demonstration that molecules of net anionic charge, but with discrete positively charged regions, exhibit affinity for the glomerular basement membrane (GBM) extends this concept. Charge hybrid (polar) molecules were constructed by covalently coupling small polycations (lysozyme or linear poly-L-lysine chains with a mean of 17 and 20 residues) to larger polyanions (ovalbumin or human serum albumin (HSA]. Although the products were of overall net anionic charge they still bound to glomerular structures. Immunofluorescence studies performed after i.v. injection of the samples into rats revealed that HSA:poly-L-lysine had the highest affinity. Radioisotopic measurements showed uptake of HSA:poly-L-lysine to be a function of the number of lysine residues; binding of HSA:poly-L-lysine20 was 2.5 times higher than HSA:poly-L-lysine17 (P less than 0.01). Prior injection of a small competing polycation (polyethyleneimine 1200) reduced uptake of HSA:poly-L-lysine by 75%, indicating the charge-based nature of the interaction. HSA:poly-L-lysine20 alone was effectively eliminated from the glomeruli within 72 h. Administration of HSA:poly-L-lysine followed by anti-HSA antibody induced immune complex formation in the capillary wall, giving rise to a granular immunofluorescence pattern and discrete subendothelial and subepithelial deposits. Molecules with polar structure do occur naturally and may contribute to immune complex formation in glomerulonephritis.

Analysis of Variance↗
PubMed1991

[Heparin-induced thrombocytopenia. Perspectives in a therapeutic dilemma].

Severe heparin-induced thrombocytopenia (HIT) is a complication of heparin treatment with a frequency of about 0.5% of the treated patients. It is attributed to an immune mechanism leading to the production of heparin-associated antibodies which bind to the platelets and cause their elimination through consumption, sometimes accompanied by thromboembolic episodes. Therapeutically HIT represents a dilemma since heparin administration must be stopped immediately, whereas anticoagulation is acutely indicated in order to avoid thrombotic complications. Two such cases with this dilemma are illustrated. The diagnosis of HIT was made using platelet aggregation studies and flow cytometry techniques for the detection of heparin-associated platelet antibodies. Therapeutically, low molecular weight heparins were administered with success. Besides the diagnostic problems other available therapeutic solutions are discussed.

Aged↗
PubMed1991

Complement and monocytes are essential for provoking glomerular injury in passive Heymann nephritis in rats. Terminal complement components are not the sole mediators of proteinuria.

Complement but not polymorphonuclear granulocytes (PMN) causes glomerular injury in passive Heymann nephritis in rats. We have now identified monocytes as another important mediator in this model. Passive Heymann nephritis was induced in Wistar rats by intravenous injection of sheep anti-rat Fx1A antiserum. Four groups (all receiving anti-rat Fx1A antiserum) were studied: (a) rats given normal sheep globulin (nephritic controls), (b) rats given sheep anti-rat PMN globulin (PMN-depleted), (c) rats given sheep anti-rat monocyte globulin (monocyte-depleted), (d) rats injected with cobra venom factor (complement-depleted). In vitro specificity controls for anti-cell antisera were made by cytotoxicity tests and inhibition of phagocytosis. In vivo specificity controls were performed in heterologous Masugi nephritis (PMN-dependent) and accelerated Masugi nephritis (monocyte-dependent). Complement and monocyte depletion significantly delayed the onset of proteinuria (p less than 0.001 versus nephritic controls on day 5), PMN depletion had no significant effect. Monocyte infiltration was seen in control nephritic rats, but monocyte depletion prevented this influx. In the monocyte-depleted group, no differences in glomerular deposition of C3, C9, and C5b-9 were seen in comparison to the nephritic control rats. Serum C3 levels were comparable in groups a, b, and c, the complement system was biologically active in the monocyte depleted-group (c), and the amount of anti-Fx1A antibody bound was the same in all groups. This shows that, besides complement, monocytes are required for induction of renal damage in passive Heymann nephritis. The concept of a sole role for complement in glomerular immune injury involving subepithelial immune deposits should be reconsidered.

Animals↗
PubMed1990

Isolation of an outer membrane protein complex from Borrelia burgdorferi by n-butanol extraction and high-performance ion-exchange chromatography.

Borrelia burgdorferi, the causative agent of Lyme disease, expresses two major membrane proteins, designated outer surface proteins A and B, which are of antigenic relevance, especially in the chronic phase of Lyme disease. Both proteins exhibit strain-related molecular weight variation. A method is described for obtaining these proteins from the bacterial membrane, without the use of detergents, by a combination of n-butanol extraction and cation-exchange chromatography on a Mono S fast protein liquid chromatographic column. This method yields up to five times larger amounts of the proteins in aqueous solution than previously described protocols, which applied ionic or non-ionic detergents. A comparison of extracts obtained by this method from different Borrelia burgdorferi strains is reported.

1-Butanol↗
PubMed1990

[The laboratory diagnosis of Borrelia burgdorferi infection].

The multiplicity of the clinical appearance of Lyme disease makes it necessary to confirm the diagnosis by detecting the pathogen or specific antibodies. Isolation of the pathogen from infected tissue or body fluids is difficult, so that, to date, only serology is feasible for routine diagnosis. In view of a lack of standardisation of borrelia serology, the clinician must expect false negative, and--even more so--false-positive, results. Future laboratory diagnosis should be markedly improved by nucleic acid hybridisation for the detection of the pathogen, and the use of specific immunodominant antigens for antibody detection.

Antibodies, Bacterial↗
PubMed1990

[Acute effects of the angiotensin converting enzyme inhibitor ramipril in patients with coronary heart disease].

We investigated the acute effect of the new long-acting ACE-inhibitor ramipril on angina-limited exercise tolerance and exercise-induced ST-depression in 18 normotensive patients with angiographically confirmed coronary artery disease in a double-blind, placebo-controlled study. Patients underwent a repeat exercise ECG 24 hours following either 5 mg ramipril p.o. or placebo. Plasma-ACE activity (nmol/min x ml) in the ramipril-group (n = 8) was significantly reduced 24 hours after 5 mg ramipril compared to placebo (n = 10): 14.0 +/- 2.0 vs 87.2 +/- 13.5, p less than 0.001. Exercise-induced ST-segment depression was not different before and after ramipril or placebo. Heart rate at rest and during angina-limited exercise was not different between the first exercise-ECG and that after ramipril or placebo, nor between the groups. Systolic arterial pressure (mmHg) was slightly, but insignificantly, lower after than before ramipril at rest (113.8 +/- 5 vs 125 +/- 6.8) and at maximal exercise, 1.5 watt/kg (150 +/- 9.4 vs 158.3 +/- 13.3). In the placebo group, blood pressure at rest and during exercise was not different before and after placebo: 126 +/- 4.7 vs 125.5 +/- 7.5 and 157.5 +/- 3.8 vs 158 +/- 3.6. Rate-pressure-product (mmHg/min x 1000) at rest prior to (8.42 +/- 0.83 and 8.95 +/- 0.51) and after ramipril or placebo (8.00 +/- 0.94 and 8.93 +/- 0.71) showed no significant difference. Similarly, rate-pressure-product at maximal exercise was equal among the groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1990

[The Borrelia titer in ENT diseases].

In 139 patients with facial paralysis, sudden hearing loss, vertigo, and lymphadenitis of the head and neck, the prevalence of borrelia burgdorferi serum antibodies was examined with the help of immunofluorescence assays for IgG- and IgM-antibodies, immunofluorescence assays after absorption of cross-reacting antibodies with treponema phagedenis, ELISA, and Western Blot. Six out of 22 patients with facial paralysis, 11 out of 72 with hearing loss, eight out of 45 with vertigo, and five out of 25 with lymphadenitis of the head and neck were seropositive. These patients were compared with a control group of 52 patients without any clinical signs of Lyme disease. The control group consisted of patients admitted for surgery of septal deformities (n = 19), squamous cell carcinomas (n = 27), and pleomorphic adenomas of the salivary glands (n = 6). In nine out of 52 patients in the control group, antibodies against Borrelia burgdorferi were detectable. According to Fisher's exact test, there was no statistical difference between the two groups as regards the prevalence of seropositive patients. Lyme disease is a doubtful major etiologic factor in facial paralysis, sudden hearing loss, or vertigo.

Adult↗
PubMed1990

The role of cationic proteins in the pathogenesis of immune complex glomerulonephritis.

In spite of intensive endeavours, attempts to identify nephritogenic antigens in cases of immune complex glomerulonephritis have not yielded convincing results. Cationic antigens can have high affinity for the glomerular basement membrane and are prime candidates as nephritogens. They can be expected to play a role in post-infectious and in autoimmune glomerular disease. Histones show great promise in the latter case: we are able to demonstrate (1) a high affinity for the glomerular basement membrane and (2) their ability to promote glomerular deposition of anionic antigens as an additional target. Histones were detectable in glomerular deposits in two murine models of glomerulonephritis: the spontaneous lupus-like disease of NZB/W F1 mice and in graft-versus-host disease. We propose that histones may be responsible for the induction of glomerulonephritis in lupus-like syndromes, as well as other types of autoimmune renal disease. As an analogue, histone-like proteins from micro-organisms may also be responsible for glomerular disease in post-infectious nephritis.

Animals↗
PubMed1989

Improved thrombolysis with a modified dose regimen of recombinant tissue-type plasminogen activator.

To improve further the patency rate of infarct-related coronary arteries, the following accelerated dosage regimen of recombinant tissue-type plasminogen activator (rt-PA) was administered to 80 patients with acute myocardial infarction of less than or equal to 6 h duration: 15 mg intravenous bolus, 50 mg infusion over 30 min and 35 mg infusion over the following 60 min. After coronary angiography at 90 min coronary angioplasty was performed in 16 patients and additional thrombolysis in 3 patients. Six patients were not included in the final angiographic analysis, mostly because of borderline ST segment elevations, in order to avoid overestimation of the efficacy of this dose regimen. Four of these had a patent infarct artery; no early angiogram was performed on two. Sixty minutes after the start of infusion, 54 (74%) of 73 patients had a patent infarct-related artery (Thrombolysis in Myocardial Infarction [TIMI] grade 2 or 3) as did 67 (91%) of 74 patients at 90 min. At 24 h, 61 (92.4%) of 66 patients showed a patent infarct artery. Recurrent myocardial ischemia was noted in 12 patients, 7 (9.4%) of whom experienced reinfarction during the hospital stay. Minor local bleeding complications were observed in 14 patients (17.5%). There were four in-hospital cardiac deaths; one patient who underwent additional thrombolysis for recurrent ischemia died from bleeding complications. These results show that a rapid infusion of 100 mg of rt-PA over 90 min yields a high early patency rate of the infarct-related artery without an increase in reocclusion rate and adverse reactions.

Adult↗
PubMed1989

N-terminal amino acid sequence of the Borrelia burgdorferi flagellin.

The 41 kDa flagellar protein of Borrelia burgdorferi appears to be an immunodominant antigen producing an early and strong response in most, if not all, individuals during infection in humans. It would represent a very good antigen for serodiagnosis of Lyme disease, if its crossreactivity with flagella of other bacteria was low. To gain information on this point we isolated the B. burgdorferi flagellin by preparative two-dimensional electrophoresis for N-terminal amino acid analysis. By comparing the N-terminal amino acid sequences of flagellar proteins from other eubacteria we found that the first six out of twenty nine amino acids were identical to the Treponema pallidum and Treponema phagedenis 'class B' flagellins. All 29 N-terminal residues exhibited a moderate inter-genus homology (44-55%), in contrast to the high degree (67-95%) of inter-species conservation of the treponemal 'class B' flagellar N-terminal sequences. There was little similarity to other flagellins except the B. subtilis flagellar protein.

Amino Acid Sequence↗
PubMed1989

Histones have high affinity for the glomerular basement membrane. Relevance for immune complex formation in lupus nephritis.

An effort has been made to integrate insights on charge-based interactions in immune complex glomerulonephritis with nuclear antigen involvement in lupus nephritis. Attention was focussed on the histones, a group of highly cationic nuclear constituents, which could be expected to bind to fixed anionic sites present in the glomerular basement membrane (GBM). We demonstrated that all histone subfractions, prepared according to Johns (4), have a high affinity for GBM and the basement membrane of peritubular capillaries. Tissue uptake of 125I-labeled histones was measured by injecting 200 micrograms of each fraction into the left kidney via the aorta and measuring organ uptake after 15 min. In glomeruli isolated from the left kidneys, the following quantities of histones were found: f1, 13 micrograms; f2a (f2al + f2a2), 17 micrograms; f2b, 17 micrograms; and f3, 32 micrograms. Kinetic studies of glomerular binding showed that f1 disappeared much more rapidly than f2a. The high affinity of histones (pI between 10.5 and 11.0; mol wt 10,000-22,000) for the GBM correlates well with their ability to form aggregates (mol wt greater than 100,000) for comparison lysozyme (pI 11, mol wt 14,000), which does not aggregate spontaneously bound poorly (0.4 micrograms in isolated glomeruli). The quantity of histones and lysozyme found in the isolated glomeruli paralleled their in vitro affinity for a Heparin-Sepharose column (gradient elution studies). This gel matrix contains the sulfated, highly anionic polysaccharide heparin, which is similar to the negatively charged heparan sulfate present in the GBM. Lysozyme eluted with 0.15 M NaCl, f1 with 1 M NaCl, and f2a, f2b, and f3 could not be fully desorbed even with 2 M NaCl; 6 M guanidine-HCl was necessary. Two further findings of great relevance for the concept of induction of immune complex glomerulonephritis by histones were: (a) glomerular-bound histone was accessible for specific antibody given intravenously; and (b) prior binding of histones promoted glomerular deposition of anionic antigens, as could be shown with ssDNA fragments. These data justify the proposal that glomerular deposition of histones can induce immune complex formation, start an inflammatory process, and produce tissue damage.

Animals↗
PubMed1989

Frequencies of Borrelia burgdorferi-reactive T lymphocytes in Lyme arthritis.

Using a limiting dilution system, frequencies of Borrelia burgdorferi-reactive T cells were determined in the blood and synovial fluid of four patients with chronic Lyme arthritis (LA), one patient with acrodermatitis chronica atrophicans (ACA), two patients with other inflammatory joint diseases, and two healthy individuals. B. burgdorferi-reactive precursor T cells ranged from 1/750 to 1/8220 in case of LA and ACA patients and from 1/820 to 1/31 400 in case of controls. In vivo activated B. burgdorferi-reactive T cells were almost absent in control subjects. With one exception, they were detected in LA patients at frequencies ranging from 1/1 300 to 1/15 400. Interestingly, even after successful antibiotic therapy of LA patients, similar frequencies of in vivo activated B. burgdorferi-reactive T cells were observed in the peripheral blood, provided that low cell concentrations were used for culture. At higher cell numbers, the fraction of B. burgdorferi-reactive T cells apparently dropped, suggesting regulatory phenomena.

Adult↗