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J Kropp

Publications and source records attributed to J Kropp.

34 records · Page 2Linked to original sources
PubMed1988

The effect of speed of deoxygenation on the percentage of aligned hemoglobin in sickle cells. Application of differential polarization microscopy.

We have used differential polarization microscopy, which provides images of linear dichroism, to measure the percentage of aligned hemoglobin (Hb) in 1086 deoxygenated red blood cells from subjects with sickle cell anemia. The percentage was found to be only slightly dependent on the speed of deoxygenation, thus showing that the percentage of aligned Hb was thermodynamically controlled (as has been found previously for the percentage of polymerized Hb in vitro). A slight decrease in the percentage of aligned Hb due to increasing speed of deoxygenation is primarily due to the increase in the number of cells containing no detectable aligned Hb. This class of cells was also the most variable between the different subjects studied. We were able to identify two other groups of cells that contain different numbers of domains of aligned Hb and show that these groups contain statistically different percentages of aligned Hb. The differences between these classes of cells was shown to be primarily due to different numbers of initial nucleation sites within each cell. It appears that the presence of preformed nucleation sites within cells at ambient oxygen tensions results in the thermodynamic control of aligned Hb polymer.

Algorithms↗
PubMed1987

Neurenteric cyst diagnosed by technetium-99m pertechnetate sequential scintigraphy.

Neurenteric cysts are rare congenital anomalies which present as mediastinal tumors associated with vertebra anomalies. Two-thirds of them are lined with gastric mucosa and are potentially life threatening. An exact differential diagnosis is difficult preoperatively but is absolutely necessary because of the grave prognosis if left untreated. We present a case in which [99mTc]pertechnetate sequential scintigraphy demonstrated gastric mucosa in the cyst and helped to confirm the diagnosis. The scintigraphic findings are correlated with radiologic, sonographic, and pathologic features.

Female↗
PubMed1986

[Results of fatty acid SPECT of the myocardium in coronary disease].

New developments in radiopharmacology of 123I-labeled metabolic tracers and single-photon emission computerized tomography (SPECT) allow now-a-days the assessment of parameters of cardiac energy metabolism in well-defined areas of the heart muscle. This article will present a brief outline of the basic pathophysiological principles used in the application of 123I-labeled phenyl fatty acids for the evaluation of CAD. First clinical results suggest an important application of cardiac fatty acid metabolic imaging to the detection, localisation and conceivable quantitation of myocardial ischemia, myocardial infarction and assessment of tissue viability. In addition to the diagnostic applications in CAD, cardiac fatty acid metabolic imaging may provide new perspectives to pathophysiological investigations of the coupling of local flow and substrate utilisation in vivo and the effect of therapeutic interventions.

Coronary Disease↗
PubMed1985

[Reduction of regurgitation in aortic and mitral insufficiency by captopril in acute and long-term trials].

Afterload reduction is an accepted therapeutic principle in the management of acute aortic (Ai) and mitral insufficiency (Mi). The question whether acute and chronic converting-enzyme inhibition by captopril has a beneficial hemodynamic effect in chronic Ai and Mi has been investigated in 17 patients with Ai and 10 with Mi. Ejection and regurgitation fraction (RF) were measured by radionuclide ventriculography (RNV) before, after 25 mg captopril and after 3-5 months of long-term treatment. The humoral response of the renin-angiotensin system (RAS) was quantified by analysis of angiotensin I and II. Captopril lowered under acute and chronic treatment RF in Ai and Mi by 32%. Angiotensin II levels decreased by the same order of magnitude. Acute and chronic vasodilation was followed by a distinct but well tolerated fall in blood pressure, especially in patients with Mi. These favourable hemodynamic effects of captopril make this therapy an adjunct but not an alternative to valve replacement.

Aortic Valve Insufficiency↗
PubMed1985

Captopril mediated decrease of aortic regurgitation.

The effect of captopril mediated afterload reduction on aortic regurgitation was investigated in 10 patients. Regurgitation was quantitated by means of the regurgitation fraction and the relation of regurgitant volume to end diastolic volume. These variables were derived from gated radionuclide ventriculography. After captopril treatment the blood concentration of angiotensin I rose whereas that of angiotensin II fell significantly. The conversion of angiotensin I to II was reduced to about 50% of the control value. Whereas blood pressure and heart rate did not change significantly, the regurgitation fraction and the regurgitant volume, normalised to end diastolic volume, were significantly reduced by captopril treatment. The ejection fraction remained essentially unchanged. These findings suggest that captopril reduces aortic regurgitation by reducing afterload.

Angiotensin I↗
PubMed1984

[Reduction of regurgitation in aortic insufficiency by inhibition of the renin-angiotensin converting enzyme].

The effect of captopril-mediated afterload reduction on regurgitation was investigated in 10 patients with aortic insufficiency. Regurgitation was quantitated by the regurgitation fraction and the relation of regurgitant volume to enddiastolic volume, which were derived from gated radionuclide ventriculography. 19 patients with coronary artery disease and no evidence of valvular heart disease served as controls. In patients with coronary artery disease no significant regurgitation was found. In patients with aortic regurgitation the blood concentration of angiotensin I increased whereas that of angiotensin II decreased significantly after captopril-medication; thus, the conversion of angiotensin I to II was reduced to about 50% of the control value. Whereas blood pressure and heart rate did not change significantly, the regurgitation fraction and the normalized regurgitant volume were significantly reduced. The ejection fraction remained essentially unchanged. These findings suggest a favorable influence of captopril-induced afterload reduction on hemodynamics in aortic regurgitation.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1983

Dietary tryptophan supplementation prevents proteinuria in the seven-eighths nephrectomized rat.

Surgical reduction of renal mass in the rat leads to proteinuria, hypertension, and progressive renal failure beyond that of the original physical destruction of renal mass. Both hypertension and proteinuria have been implicated in the process of progression of renal failure. The seven/eighths nephrectomized rats fed a diet supplemented with 4% tryptophan (UT) had a urinary albumin excretion rate of 0.055 +/- 0.056 mg/100 g body weight/hr compared to 0.02 +/- 0.029 mg/100 g body weight/hr in control rats, whereas the nephrectomized rats fed a regular diet (UR) excreted 1.12 +/- 0.730 mg/100 g body weight/hr (P less than 0.001). Hypertension was also prevented in the UT group but not in the UR group. Once hypertension and proteinuria were established during maintenance on a regular diet, they were not reversed by subsequent dietary tryptophan supplementation. If dietary tryptophan supplementation is continued, however, the progressive histopathology that develops after seven-eighths nephrectomy is not prevented despite avoidance of proteinuria and hypertension.

Albuminuria↗
PubMed1977

Membrane phospholipid composition and anaphylactical response of cardiac and smooth muscle fibers in the Rh (D) system.

The anaphylactical response of sensitized smooth and cardiac papillary muscle fibers as target organs was induced by the stimulation of the complement systems in the antigen-antibody reaction of albumin and anti-albumin. However in the Rh (D) system anaphylaxis was only elicited on smooth muscle segments with the corresponding antigen. This discrepancy between both immune systems cannot be explained only by the fact the Rh (D) anti-D reaction does not stimulate the complement activity. Since this antigen-antibody reaction requires a protein phospholipid interaction, the failure of anaphylactical response on cardiac muscle fibers may be due to its phospholipid environment which differed considerably from that of the smooth muscle fibers. Besides the differences in composition and amount of the phospholipids the fatty acid distribution of phosphatidylethanolamine, phosphatidylcholine, sphingomyelin, cardiolipin derived from cardiac or smooth muscle membranes varied clearly. This may influence the protein phospholipid interaction which is essential for the antigen-antibody reaction of the Rh (D) system.

Anaphylaxis↗
PubMed1975

[The importance of phosphatidylcholine in the binding of anti-D to human erythrocyte ghost membrane (author's transl)].

Incubation of Rh positive ghosts with phospholipase A2 and C abolished the adsorption of Rh antibodies on the ghosts; incubation with phospholipase D, however, did not affect their adsorption and none of these phospholipases affected the adsorption of antibodies of the ABO system. The impairment of antigen-antibody-reaction in Rh positive ghosts treated with phospholipase corresponds to the absence of the antigen-antibody reaction with the membrane protein associated with Rh characteristics in the Schultz-Dale-Test. The chromatogram of the phospholipids extracted from those stromata treated with various phospholipases and those not treated showed different patterns. After incubation with phospholipase-A2 the lecithin and cephalin streaks were reduced and in addition lysophosphatide and fatty acid streaks were detected. In the case of phospholipase C the lecithin and cephalin streaks were further reduced while diglyceride streaks made their appearance. The phospholipid extracts from those stromata treated with phospholipase D and those not treated were identical. Phospholipase C reduced the values of lipid phosphorus more than did phospholipase A2, while phospholipase D did not reduce them at all. This study supports the results of other investigators who have postulated that the Rh antigens are located in a lipoprotein on the membrane of the human erythrocyte. The antigen-antibody-reaction seems to require a precise protein-phospholipid interaction.

Binding Sites, Antibody↗