Elias Amador

Serum cholesterol measurement based on ethanol extraction and ferric chloride-sulfuric acid.

Abstract Extraction of serum with ethanol permits the isolation and direct determination of total cholesterol concentration. A modified ferric chloride-sulfuric acid reagent is employed for the color reaction. Cholesterol appears to be extracted completely from serum (0.1 ml) by ethanol (1.9 ml), as shown by the absence of cholesterol in the serum precipitate. Total cholesterol is measured by reacting the ethanol extract (0.5 ml) with ferric chloride-ethyl acetate (100 mg/100 ml, 2 ml) and concentrated sulfuric acid (2 ml). The colored product obeys Beers law and has a peak absorbance at 560 mμ. Free cholesterol and its esters give equivalent absorbances; 7-dehydrocholesterol, pregnenolone, cholestanol, squalene and lanosterol give practically no color. The reaction is specific as shown by thin-layer chromatography and by complete removal of the chromogen precursors from the ethanol extract by digitonin. The proposed method correlates (1:1) with the method of Abell et al., has a repeatability of 0.7%, a day-to-day variability of 2.8% and a reproducibility between laboratories of 1%. Bilirubin and bromide do not interfere. The simplicity, speed, and reliability of the proposed method make it suitable for large scale analysis.

Urinary Alkaline Phosphatase and LDH Activities in the Differential Diagnosis of Renal Disease

Excerpt Urinary alkaline phosphatase and lactic dehydrogenase (LDH) activity measurements provide specific and sensitive tools for the detection and diagnosis of urologic disease. Both the urinary ...

Serum lactic dehydrogenase activity and radioactive lung scanning in the diagnosis of pulmonary embolism.

Excerpt The serum lactic dehydrogenase (LDH) activity is an accurate and sensitive tool for the detection and diagnosis of certain life-threatening cardiovascular diseases such as myocardial infarc...

Bilateral adrenalectomy for hypertensive vascular disease: Hormonal requirements in the presence of renal insufficiency: Body potassium in chronic hyperkalemia☆

Abstract The history is reported of a thirty-four year old white man who survived four and a half years following bilateral total adrenalectomy for cardiac failure due to hypertension. Marked improvement in circulatory status and a notable decrease in heart size was observed postoperatively although the degree of reduction in blood pressure level was minimal. Progressive renal insufficiency developed during the four and a half-year period, and as this occurred there was an increasing requirement for both salt and salt-retaining hormone. Chronic hyperkalemia with intermittent clinical episodes of acute potassium intoxication developed. However, the total exchangeable body potassium during this time was found to be within normal limits. A review of the autopsy tissue revealed no reversal of the arteriolar disease noted in renal biopsies at the time of adrenalectomy. The rapid reversal of acute potassium intoxication by administration of DOCA suggests a direct effect of this hormone on the mechanism involved in sustaining the normal gradient of potassium concentrations across the cell membranes.

Dynamics of normal and diseased cardiac valves

Abstract The function of normal and diseased cardiac valves was studied with a modified McMillan cardiac pulse duplicator. Opening of normal mitral and tricuspid valves depends on flexible valve leaflets and intact commissures; closure depends on sufficient leaflet substance to occlude the valve orifice, flexibility of the leaflet edges to permit fluid-tight seal, and intact chordae tendineae to prevent leaflet eversion. Competent closure of the tricuspid valve necessitates contraction of the myocardium surrounding the valve annulus. In mitral stenosis, fibrous thickening and retraction of the leaflets, and fusion of the commissures are the basic lesions; they vary from mild to moderate commissural fusion in some hearts to severe commissural fusion with thick, inflexible, and calcified leaflets in others. Associated fusion, shortening, and rigidity of the chordae tendineae further reduce leaflet mobility. Mitral valvuloplasty may significantly increase the area of the valve orifice, without significantly increasing any insufficiency already present. Opening of the semilunar valves depends on flexible cusps and intact commissures. Adequate closure depends on sufficient cusp substance, and on the cup-shape of the cusps which permits them to support high pressures without prolapsing. Aortic stenosis results from commissural fusion and/or from calcific deposits within the sinuses of Valsalva. Either splitting of the commissures or removal of the calcific deposits corrected this type of stenosis without leading to insufficiency. Aortic stenosis and insufficiency result form fusion and retraction of the valve cusps, with obliteration of the commissures and of the sinuses of Valsalva. Careful splitting of the residual commissures permitted the cusps to abut during diastole, and insufficiency was not increased. Aortic insufficiency commonly results from loss of cusp substance, aggravated by sagging of the cusps and by dilatation of the aortic ring. The use of aortic prosthetic valves appears to be the most promising method for correction of this lesion.