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Biomedical subjects

E Haber

Publications and source records attributed to E Haber.

At least 253 records · Page 14Linked to original sources
PubMed1978

Inhibition of angiotensin-converting enzyme for diagnosis of renal-artery stenosis.

To determine its utility as an aid in diagnosis of renovascular hypertension, we administered nonapeptide converting-enzyme inhibitor (CEI) (which inhibits conversion of angiotensin I to angiotensin II) (0.25 mg per kilogram) to 14 unselected hypertensive patients undergoing bilateral renal-vein catheterization. In seven (Group I) predominantly unilateral disease was discovered by angiography (renal-artery stenosis in six and hydronephrosis in one); in the remaining seven (Group II) no rennal-artery abnormality was found. In Group I, mean (+/- S.E.) ratio of involved to uninvolved renal-vein plasma renin activity (PRA) increased from 2.94 +/- 0.91 before to 8.36 +/- 2.94 after CEI (P less than 0.01). In Group II, the ratio (of the initially higher to the lower side) was 1.99 +/- 0.49 before and 1.17 +/- 0.07 after CEI (P greater 0.02). Post-CEI PRA was predicted by pretreatment PRA. Mean blood pressure fell in both groups after CEI, and the decrement was predicted by pre-CEI PRA. These data suggest that CEI can be of use at the time of renal-vein catheterization, serving to increase diagnostic accuracy by increasing the difference in PRA between the two sides when there is unilateral disease.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1978

Purification of human renal renin.

1. Human renal renin has been purified 200 000-fold from cadaver kidney cortex by a method which employs affinity chromatography on aminohexyl peptstatin. 2. The product of this purification has a specific activity of 400 Goldblatt units/mg when compared with Haas human renin standard. 3. This product appears as a single band on sodium dodecyl sulphate gel and polyacrylamide-disc gel electrophoresis. Renin enzymatic activity was recovered after elution from a polyacrylamide-disc gel run at pH 7.8. 4. Yield with this method was 1%.

Chromatography, Affinity↗
PubMed1978

Affinity purification of cardiac adenylate cyclase: dependence on prior hydrophobic resolution.

The interaction of cardiac adenylate cyclase [ATP pyrophosphate-lyase (cyclizing); EC 4.6.1.1] with a variety of nucleotide affinity resins was systematically investigated. None of these resins effectively bound the native, detergent-solubilized enzyme. However, after hydrophobic resolution on an uncharged resin consisting of long-chain alkyl groups linked to agarose via ether bonds, 40% of the adenylate cyclase activity biospecifically adsorbed to an ATP affinity resin. Gel filtration without detergent after hydrophobic chromatography demonstrated that the enzyme eluted in the identical position as the native enzyme chromatographed in the presence of detergent. This preparation almost completely biospecifically adsorbed to the same ATP-resin and was not eluted with 5 mM cyclic AMP, pyrophosphate, or GTP. If the GTP-washed immobilized enzyme was subsequently desorbed with ATP, then expected Gpp(NH)p (5'-guanylyliminodiphosphonate) sensitivity persisted. A preliminary purification scheme that resulted in an approximate 5000-fold increase in specific activity is presented. These observations indicate that a membrane-bound enzyme may appear to be intrinsically hydrophobic only by virtue of aggregation with other hydrophobic constituents and that prior separation of hydrophobic chromatography may permit such proteins to be fractionated subsequently by methods conventionally applied to hydrophilic proteins.

Adenosine Triphosphate↗
PubMed1978

Detection of serum cardiac myosin light chains in acute experimental myocardial infarction: radioimmunoassay of cardiac myosin light chains.

To develop a more specific plasma test for myocardial infarction, antibodies specific for cardiac myosin light chains (CM-LC) were elicited that showed less than 3% cross-reactivity with skeletal muscle light chains. These antibodies were used to develop a radioimmunoassay for CM-LC that had a sensitivity of 20 ng (+/- 4 SD; P less than 0.001). Normal dog plasma showed no measurable concentrations of CM-LC (n = 6). Plasma samples from 10 dogs with experimental myocardial infarction produced by persistent left anterior descending coronary artery (LAD) occlusion were obtained at 0, 2, 4, 6, 24, 48 and 72 hours. CM-LC were first detectable in all 10 animals 6 hours after occlusion (97.98 +/- 14 ng/ml [mean +/- SEM]; P less than 0.001). Maximal CM-LC levels were usually obtained between 24 and 48 hours. Sham-operated open chest dogs (0--48 hours, n = 3) showed no measurable CM-LC in the plasma samples. Another group of 10 dogs were subjected to 5 hours of LAD occlusion, followed by reperfusion. In four dogs, CM-LC were detectable as early as 1 hour after reperfusion (81.88 +/- 37.75 ng/ml serum). Sera from all 10 dogs showed elevated levels of CM-LC (199.75 +/- 24.0 ng/ml) by 24 hours. Peak CM-LC concentrations were obtained in five dogs at 24 hours (247.0 +/- 35.28 ng/ml) and in another dog at 120 hours (245 ng/ml). Histochemical infarct size was determined to be 0.5--10% of the left ventricular mass at seven days by triphenyltetrazolium chloride staining. The specificity and sensitivity of this radioimmunoassay for detection of CM-LC, unique proteins to the heart, may be valuable in the diagnosis of myocardial infarction.

Acute Disease↗
PubMed1978

Early imaging of experimental myocardial infarction by intracoronary administraion of 131I-labelled anticardiac myosin (Fab')2 fragments.

We examined the feasibility of early imaging of myocardial infarcts by intracoronary injection of 131I-labelled cardiac myosin-specific antibody (Fab')2. The left anterior descending coronary artery was occluded for 5 hours by a balloon catheter introduced through the carotid artery in 12 dogs. The catheter was withdrawn and 1 mCi 201Tl was injected intravenously and 500 muCi of 131I antibody were injected into the main left coronary artery. Six of these animals demonstrated evidence of myocardial infarction by ECG and subsequent triphenyl-tetrazolium chloride staining, while the others did not. In each of the infarcted animals, in vivo scintograms one-half hour after injection of isotope showed uptake of 131I in the anteroapical region of the heart corresponding to the region of absent 201Tl uptake. This relationship was confirmed in the excised hearts and in heart slices. In slices, 131I uptake corresponded to regions that did not stain with triphenyltetrazolium chloride. In the six animals that did not show evidence for infarction after coronary occlusion, uptake of 131I was not demonstrated, either in vivo or in excised specimens. In four additional dogs subjected to the same procedure, 125I-labelled (Fab')2 from nonimmune IgG was injected simultaneously into the left main coronary artery with 131I-labelled canine myosin-specific antibody (Fab')2. The ratio of uptake between infarct center and normal tissue was 34.3 +/- 1.5 (mean+/-SEM) for the specific antibody fragment as contrasted to 6.6+/-0.4 for the nonimmune IgG fragment, indicating that intracoronary injection does not favor nonspecific sequestration of protein in regions of infarction. Thus, the intracoronary administration of myosin-specific antibody fragments leads to early and specific one-half hour imaging of myocardial infarcts.

Animals↗
PubMed1978

Volume as a determinant of plasma aldosterone in anephric man.

Previous studies from this laboratory have demonstrated that the redistribution of blood volume and concomitant central hypervolemia induced by water immersion to the neck (NI), produces a prompt and profound suppression of plasma renin activity (PRA) and plasma aldosterone concentration (PA) without concomitant alterations in serum sodium and potassium concentrations. The NI model was utilized to assess the responsiveness of PA to volume expansion in 12 anephric subjects. The patients were studied on 2 occasions, 48 h after their last dialysis: during a seated control study (7 of the patients) and during 3 h of NI (all 12 patients). The conditions of seated posture and time of day were identical. Blood for PRA, PA, and cortisol was obtained at 30-min intervals for 5 h. PRA was undetectable in all patients. NI failed to alter PA. Plasma cortisol declined progressively throughout NI; serum potassium concentration remained unchanged. An identical NI study in normal subjects suppressed PA by 60%. These data demonstrate that when plasma composition and posture are maintained constant, marked central hypervolemia does not alter PA in anephric man. The present findings support the role of the renin-angiotensin system as the prepotent mediator of volume-induced changes in PA.

Adult↗
PubMed1978

A large form of renin from normal human kidney.

The apparent molecular size of circulating human plasma renin is 43,000 daltons. In this report, the Stokes' radius of renin extracted from human kidney cortex in low ionic strength buffer in the presence of protease inhibitors was shown to correspond to an apparent molecular weight of 58,000 +/- 3,000. If protease inhibitors are omitted, if the kidney tissue is frozen and thawed multiple times, or if the kidney extract is acidified to pH 2.8, renin activity of an apparent molecular size of 42,000 +/- 3,000 can be identified. Both species of renin bind to an affinity support bearing the substrate analog inhibitor His-Pro-Phe-His-Leu-D-Leu-Val-Tyr. Antibody raised to the higher molecular form of the enzyme inhibits the activity of both forms in an equivalent manner. These observations suggest that the larger form of renin may be a biosynthetic precursor of plasma renin, either in the form of a zymogen or an enzyme-binding protein complex.

Binding Sites↗
PubMed1978

A direct microassay for aldosterone in plasma extracts.

We previously described an RIA for aldosterone based on highly specific antibodies elicited with aldosterone-3,20 dioxime bovine gamma-globulin (Poulsen, K. J. Sancho, and E. Haber, Clin Immunol Immunopathol 2: 373, 1974). We now report the development of higher affinity antibodies of similar specificity that allow the direct measurement of normal aldosterone concentrations in extracts of 100 microliters plasma. The detection limit at +/- 2 SD of mean zero value was 0.2-0.3 pg. The assay was validated by 1) zero values in adrenalectomized plasma, 2) parallel displacement plots of aldosterone standards and plasma extracts, 3) 97.7 +/- 2.5% recovery of added tracer, 4) a correlation coefficient of 0.992 and a slope of 1.08 in a plot of added vs. recovered unlabeled aldosterone, 5) 10.2% interassay variation and 5.6% intraassay variation, and 6)failure of high concentrations of a variety of steroids added to plasma to perturb the measured aldosterone concentration. The simplicity of the assay results in a high degree of productivity, in that 195 plasma samples may be processed in duplicate, in addition to standard curves, in a single working day.

Aldosterone↗
PubMed1978

Antibodies of restricted heterogeneity directed against the cardiac glycoside digoxin.

Intravenous injection of New Zealand White rabbits with type III pneumococcal polysaccharide vaccine conjugated with the cardiac glycoside digoxin resulted in the production of both antidigoxin and anti-type III pneumococcal polysacharide antibodies. Among antisera of 12 rabbits examined during their peak antibody production periods, 1 to 20 mg (mean, 5.4 mg) of antidigoxin antibody could be recovered from 1 ml of serum. Antisera from five of these 12 rabbits contained antidigoxin antibodies of restricted heterogeneity as demonstrated by urea-polyacrylamide disc gel electrophoresis of fully reduced and alkylated antibodies. From the antisera of four of these five rabbits, electrophoretically homogeneous antibodies (1 to 5 mg/ml antiserum) could be isolated by affinity chromatography on ouabain-amine-Sepharose columns. The structural homogeneity of two of these antidigoxin antibodies was confirmed by amino acid sequence analysis of purified light chains through the first hypervariable region. These data suggest that the conjugation of small molecules to bacterial polysaccharide vaccines may provide a general method for synthesis of immunogens that can regularly elicit antihapten antibodies of restricted heterogeneity.

Amino Acid Sequence↗
PubMed1977

Amino acid sequence of normal (microheterogeneous) porcine immunoglobulin lambda chains.

The partial amino acid sequence of pooled, microheterogeneous pig immunoglobulin lambda chains was determined previously (Franĕk, F. (1970), FEBS Lett. 8, 269; Novotný, J., and Franĕk, F. (1975), FEBS Lett. 58, 24). In the present study, citraconylated pig lambda chains were digested by trypsin under conditions in which some of the epsilon-amino groups of lysine residues unmask. The resulting fragments were purified by gel filtration and ion-exchange chromatography at pH 3.0 in buffers containing urea; some of the fragments were found to be of intermediate size (i.e., larger than normal tryptic peptides but smaller than "citraconyl" peptides), thus permitting overlap information and amino acid sequences of all the 14 tryptic peptides to be deduced from amino acid compositions and partial amino acid sequences of selected fragments. In addition to completing the major amino acid sequence of pig immunoglobulin lambda chains, the present study demonstrates that it is possible to sequence microheterogeneous proteins with a suitable fragmentation strategy.

Amino Acid Sequence↗
PubMed1977

Localization of radiolabeled cardiac myosin-specific antibody in myocardial infarcts. Comparison with technetium-99m stannous pyrophosphate.

The myocardial uptake of radioiodinated (Fab')2 fragments of antimyosin antibody [125I-(Fab')2] was compared with simultaneously administered 99mTc-pyrophosphate (Tc-PYP) in dogs undergoing coronary occlusion for 24 (N=6) or 72 hours (N=5). Relative concentrations of both agents in normal and infarcted myocardium were related to regional blood flow as determined by distribution of 55Sr-labeled microspheres in the same animals. There was an inverse exponential relationship between 125I-(Fab')2 localization and regional blood flow in 24 hr (r=-0.64) and 72 hr (r=-0.80) occluded animals. The greatest uptake of 125I-(Fab')2 was observed in subendocardial layers of the center of the infarct where regional flow was most severely impaired (1-10% of normal flow). Maximal localization of Tc-PYP was observed in subepicardial layers in samples from the periphery of the infarct where flow was only moderately reduced (31-50% of normal). Differences in distribution of these two agents in ischemic myocardium are probably related to differences in kinetics of exit from the blood pool.

Animals↗