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Biomedical subjects

A Vogt

Publications and source records attributed to A Vogt.

At least 145 records · Page 8Linked to original sources
PubMed1987

Size restriction in the glomerular capillary wall: importance of lamina densa.

Cationized monomeric, dimeric and oligomeric ferritins (pI maxima 9.3 to 9.6) were used to study size restriction in the rat glomerular capillary wall. Monomer and dimer ferritins were able to penetrate the lamina densa; trimer and larger aggregates could not, even though they were able to enter the lamina rara interna. This demonstrates that the lamina densa is a size restrictive barrier, cationic molecules with a Stokes-Einstein radius exceeding a value between 6 to 12 nm are excluded. Monomeric and dimeric cationic ferritins were handled differently in the lamina rara externa; monomer accumulated perferentially immediately below the slit membrane whereas dimer was found within the inner regions of the rara externa, nearer to the lamina densa.

Animals↗
PubMed1986

[Acute coronary angiography in therapy-refractory angina pectoris].

UNLABELLED: Emergency coronary angiography was performed in 188 patients with treatment-resistant unstable angina. Criteria analysed were: duration of angina less than 72 h; angina despite heparin and nitroglycerin infusion; no significant S-T segment elevation in the ECG; creatine-kinase rise up to 150 U/l. Coronary heart disease (CHD) was found in 130 patients (group A). In 47 of them a recent coronary occlusion was demonstrated angiographically (main stem: 1; anterior interventricular branch: 8; circumflex branch: 27; right coronary artery: 11 patients). An at least 90% occlusion of one coronary artery was found in 58 patients. A 75% stenosis of several vessels was found in 25 patients making it impossible to identify the vessel that had caused the angina. A bypass operation was performed in 62 patients within two weeks. During the acute coronary angiography, intracoronary streptokinase infusion was performed in 11 (success rate 55%), percutaneous transluminal coronary angioplasty in 26 (success rate 88%). In 58 patients (group B) CHD was excluded. The final diagnosis in these was: mitral valve prolapse (31); pericarditis (6), dilated cardiomyopathy (3); coronary anomaly (3); muscle bridge in the anterior interventricular branch (2): normal (13). CONCLUSION: It is not possible to decide with certainty, in the absence of typical infarction signs in the ECG and clinically, whether treatment-resistant angina is due to CHD or other causes. Acute coronary angiography is indicated in such cases, because even without S-T segment elevation an acute coronary occlusion is present in 25%, and in 50% of cases an acute therapeutic intervention is indicated.

Adult↗
PubMed1986

Mediator systems in a passive model of in situ immune complex glomerulonephritis. Role for complement, polymorphonuclear granulocytes and monocytes.

The pathogenetic roles of complement, polymorphonuclear granulocytes, and monocytes were studied in a model of in situ immune complex glomerulonephritis employing a cationized antigen. Left kidneys of Wistar rats were perfused with 40 micrograms of cationized human IgG (isoelectric point greater than or equal to 9.5) followed by intravenous injection of rabbit anti-human IgG 1 hour later. This resulted in prominent subepithelial deposit formation in the perfused kidney accompanied by massive proteinuria. Groups examined were: (a) no additional treatment, (b) C3 depleted (cobra venom factor, (c) granulocyte depleted (specific antiserum), (d) monocyte depleted (specific antiserum), and (e) granulocyte depleted and monocyte depleted. The quantity of radiolabeled cationized antigen deposited in the left kidney was not affected by any of the treatment schedules. Proteinuria was abolished in all mediator depleted groups (b to e) for 5 to 7 days, thereafter rising to levels seen in the nondepleted group (a). This late onset of proteinuria is noteworthy since the deposits are then located subepithelially and may be less accessible to circulating mediators. C3 depletion, despite inhibition of proteinuria, did not prevent the intraglomerular accumulation of granulocytes and monocytes thereby suggesting that attraction and activation of these cells may occur independently. Apparently all three mediators are required for full expression of the lesion, a finding not paralleled in other experimental models of glomerulonephritis. The relevance of very low levels of inflammatory cell infiltration for provoking glomerular injury was clearly demonstrated.

Animals↗
PubMed1986

The effect of protamine sulfate on the course of immune complex glomerulonephritis in the rat.

In vivo studies in rats demonstrated that the binding of a highly cationic antigen (cationized human IgG, pI greater than 9.5) to glomerular polyanion could be significantly reduced by prior application of a small polycation, protamine sulfate. The degree of inhibition was dose dependent and the highest dose used, 4 mg/100 g body weight, reduced antigen binding by approximately 70%. In further experiments the ability of protamine sulfate to enhance elimination of cationic antigen-antibody immune complexes from the glomerular capillary wall was examined. Daily treatment with protamine sulfate, starting after induction of nephritis, produced a significant but only moderate reduction in the persistence of the antigen, without having any effect on proteinuria. Proteinuria could only be prevented when protamine sulfate was given immediately before induction of nephritis. Protamine sulfate had little influence on the course of established renal disease in the model employed. These results do not substantiate the concept of charge competition as a potentially useful therapeutic strategy.

Animals↗
PubMed1986

[Occlusion of the common trunk of the left coronary artery. Physiopathological features and clinical findings].

The total occlusion of the left main coronary artery is rarely observed (approximately 0.05% of coronary angiographic studies). We have tried to draw the clinical and pathophysiological outline of this condition, starting from our experience and reviewing the published reports. A hard selection, principally by the high mortality in patients with left main coronary stenosis, limits the number of those who present total occlusion. These subjects show a remarkable variability in their clinical presentation. It is not possible to find out a significant correlation with a single risk factor, clinical manifestation or electrocardiographic picture. Therefore, these patients cannot be distinguished from other subjects affected by severe atherosclerotic ischemic heart disease. The angiographic finding of a dominant right coronary artery is most frequent. A rich collateral circulation to the left coronary is usually observed. From a pathophysiological point of view, the efficiency of coronary collateral circulation is confirmed by the significant correlation of its extent with the left ventricular function. An important role is also played by the rate of progression of left main stenosis in total occlusion and by the presence of right coronary lesions. Even if statistical evidence is still lacking, surgical treatment is unanimously indicated and achieves satisfying results. The use of nonsurgical recanalization techniques, such as intracoronary thrombolysis and transluminal angioplasty, may be lifesaving in those patients in whom left main coronary occlusion suddenly occurs.

Angiography↗
PubMed1986

[Hemodynamic effect and duration of action of Deponit 10 in patients with congestive heart insufficiency].

The haemodynamic effect of transdermal nitroglycerin treatment with Deponit 10 was investigated in 10 patients with chronic cardiac failure due to coronary artery disease (8 patients) or congestive cardiomyopathy (2 patients). The patients had elevated mean pulmonary artery (PA) and pulmonary capillary wedge pressures (PC) at rest (32.1 +/- 5.9 and 24.1 +/- 6.6 mm Hg). Heart rate (87 +/- 10), arterial blood pressure (133 +/- 20/77 +/- 8 mm Hg) and cardiac index (3.73 +/- 0.85 l/min/m2) were in the normal range. During treatment with Deponit 10 mean PA and PC pressures decreased significantly (p less than 0.01) to 25.5 +/- 6.3 and 18.1 +/- 6.4 mm Hg, respectively. The effect was seen within 1 hour after application of the transdermal therapeutic system and reached its nadir after 2 hours. PA and PC pressures remained significantly below control for 12-16 hours. Heart rate, arterial blood pressure and cardiac index were not changed. After removal of the patch 4 patients showed a rebound haemodynamic deterioration. Their mean PA pressure rose by more than 4 mm Hg above the respective control values. These patients had the highest control PA pressures of the group studied (37.5 +/- 2.4 mm Hg). Thus, transdermal nitroglycerin treatment with Deponit 10 reduces cardiac preload in patients with congestive heart failure for 12-16 hours, whereas cardiac afterload remains unaffected. After removal of the patch a rebound phenomenon can occur especially in patients with severe cardiac failure.

Administration, Cutaneous↗
PubMed1986

Effect of cyclosporine on in situ immune complex glomerulonephritis.

The influence of Cyclosporine A (CyA) on the development of renal injury in in situ immune complex glomerulonephritis (ICGN) in rats was examined. Left kidneys of male Wistar rats were perfused with cationized human IgG followed by an intravenous injection of rabbit anti-human IgG. CyA was given orally in a dosage of either 2.5, 15 or 25 mg/kg body weight per day in two daily injections. The amount of immune complexes deposited in the left kidney was not affected by CyA application as shown by isotopic studies. There were no differences between the control and CyA groups in respect to immunofluorescence, light and electron microscopy. Proteinuria was significantly inhibited with all treatment schedules, even when rats were first treated five days after inducing nephritis. These results show that CyA inhibits proteinuria without affecting glomerular cell accumulation/proliferation in in situ ICGN, and indicates that cellular activation at glomerular level might be prevented by CyA.

Animals↗
PubMed1986

Mitogenic activity of extracellular cationic products produced by group A streptococci; analysis of the lymphocyte response.

The cationic fraction (isoelectric point greater than 8.5) of supernatant products of group A streptococcal cultures exerted a strong mitogenic effect on human peripheral lymphocytes at concentrations as low as 1 ng/well. Incorporation rates were highest at concentrations of 1-10 micrograms; rabbit peripheral lymphocytes also responded strongly, only a weak response was seen with mouse peripheral lymphocytes and rabbit thymocytes. Purified OKT4 positive (T helper) and OKT8 positive (T suppressor) lymphocyte subpopulations both responded, the former more strongly. Although accessory cells (monocytes) were not absolutely necessary, in their presence higher incorporation of 3H-thymidine was observed. Isolated B cells did not respond.

Animals↗
PubMed1985

Ultramicroscopic localization of cationized antigen in the glomerular basement membrane in the course of active, in situ immune complex glomerulonephritis.

The sequence of antigen localization and the interaction of immune deposits with the anionic sites of the glomerular basement membrane (GBM) were investigated in an active model of in situ immune complex glomerulonephritis using a cationized ferritin. Three weeks after immunization with native horse spleen ferritin, the left kidneys of rats were perfused with 500 micrograms of cationized ferritin through the left renal artery. One h after renal perfusion, most of ferritin particles localized subendothelially, corresponding to the anionic sites of the lamina rara interna. In the glomerular capillary loops, infiltrating polymorphonuclear leukocytes and monocytes were seen. Some of these monocytes were in direct contact with immune complexes containing ferritin aggregates associated with anionic sites of the lamina rara interna. At 24 h, numerous ferritin aggregates were present subepithelially, preferentially beneath the slit membrane. The subepithelial location of ferritin did not always correspond to the anionic sites of the lamina rara externa. From days 3 to 7, there was remarkable endocapillary cell proliferation in some loops and pronounced effacement of epithelial foot processes. Focal detachment of epithelium from the GBM was observed occasionally. From days 14 to 28, most of ferritin aggregates were located intramembranously and subepithelially. Membranous transformation has already begun around the subepithelial deposits. This morphological study provides insight into the fate of immune deposits and injury to the GBM in the glomerulonephritis.

Animals↗
PubMed1985

Studies on the mesangial handling of protein antigens: influence of size, charge and biologic activity.

The influence of certain physicochemical and biologic properties of protein antigens on their handling by the glomerular mesangium was studied in rats. The following ferritin-based probes were employed: (a) naturally occurring ferritin isomers to examine the role of molecular size; (b) chemically cationized ferritins (pI 7.1 and 8.8) to test charge effects; (c) glutaraldehyde (GA-)coupled ferritin as an analogue of a toxic molecule. Molecular size was found to be a major determinant of the extent and rapidity of antigen uptake, but had only a minor influence on persistence. The rapidity of uptake and antigen persistence was charge dependent, but to a limited extent. Biologic activity of macromolecules appears to be a very important determinant of mesangial handling since GA-treated ferritin was taken up much more rapidly and to a greater extent than native ferritin, and could persist for very prolonged periods.

Animals↗
PubMed1985

[Noninvasive determination of stroke volume with spectral Doppler echocardiography].

To assess the determination of volume flow by Doppler echokardiography 15 patients were studied twice in intervals of 2 to 6 hours. Cardiac output was determined simultaneously by thermodilution and by Doppler echocardiography. In three patients (20%) no Doppler signal could be recorded. In the 24 successful determinations a correlation of r = 0.93 was found between the two techniques. Mean deviation was 0.57 l/min (0.15-1.16), 9% (1-20%) respectively. With serial measurements the correlation for changes in cardiac output was 0.94. Mean deviation was found to be 0.47 l/min (0.12-1.16), or 75% (9-395%). Thus, gross estimation of cardiac output by Doppler echocardiography seems possible. However, it cannot be judged as of yet whether a more than semiquantitative estimation of individual cardiac output changes is possible nor whether further information can be obtained besides that which is clinically available.

Blood Flow Velocity↗