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Biomedical subjects

J Abrams

Publications and source records attributed to J Abrams.

At least 199 records · Page 11Linked to original sources
PubMed1983

Nitroglycerin and long-acting nitrates in clinical practice.

Nitrates are potent relaxers of vascular smooth muscle and act by dilating veins, arteries, and arterioles (especially at high doses). Their clinical effects have been considered to be dominantly related to peripheral actions: systemic venodilatation and a decrease in systemic vascular resistance, reducing the preload and afterload of the heart. Considerable experimental work confirms potent salutary effects on the coronary circulation. These drugs are readily absorbed across mucosal surfaces; they are available in multiple formulations, including sublingual, buccal, oral, and topical delivery systems. Nitrate administration should begin with low doses and increased to doses that are often higher than previously recommended until a specific clinical end point or limiting side effects occur. Organic nitrate esters are effective in the treatment of stable angina pectoris, unstable angina, coronary vasospastic syndromes, and in vasodilator therapy in severe congestive heart failure. The pathophysiology of these syndromes is reviewed with respect to the clinical actions of nitrates on the central and peripheral circulations. The side effects of nitrates include headache, dizziness, and nausea. Nitrate tolerance, a controversial subject, does not appear to be an important clinical problem. Using the guidelines presented in this review, nitrate therapy provides effective, inexpensive, well-tolerated therapy for many patients with cardiovascular disease.

Angina Pectoris↗
PubMed1983

Clonal anergy: inhibition of antigen-driven proliferation among single B lymphocytes from tolerant animals, and partial breakage of anergy by mitogens.

Mice were injected with fluoresceinated human gamma globulin (FLU-HGG) either at 2-3 days of age or as pregnant females. At 2 weeks of age, the spleen cells of the injected suckling mice or offspring were fractionated on FLU-gelatin dishes to yield FLU-binding B cells. These B cells were then cloned in microcultures using one of two recently described systems in which single B cells grow in the absence of feeder or filler cells, namely following stimulation with FLU-polymerized flagellin (FLU-POL) and conditioned media containing B cell growth and differentiation factor(s); or mitogenic activation by a mixture of E. coli lipopolysaccharide (LPS) and dextran sulfate (DxS). As such cultures permit visualization of clonal proliferation as well as ultimate harvesting of cultures for assay of hemolytic plaque-forming cells, it was possible to ask whether the lesion in the tolerant state affected the B cell's capacity to divide, to differentiate to antibody secretion, or both. The results indicated that, when stimulated with antigen, the anergic cells could neither divide nor differentiate. However, when the strong mitogen mixture was used, clonal anergy was partially broken. The cells proliferated, and a small proportion of them differentiated into anti-FLU antibody-forming cells. A marked variation in antigen-binding avidity of the FLU-binding cells made it difficult to quantitate the degree of uncoupling of proliferation and differentiation among tolerant, LPS plus DxS-stimulated cells. Nevertheless, a partial reversibility of clonal anergy must affect views on mechanisms of self-tolerance.

Animals↗
PubMed1983

New nitrate delivery systems: buccal nitroglycerin.

BN, a new nitrate formulation, has recently been made available. The main advantages of this medication is the combination of prompt onset of action, comparable to that of sublingual NTG, and sustained activity that persists for many hours. The tablet remains pharmacologically effective as long as it remains in the buccal pouch. A variety of studies indicate that BN is well tolerated by patients, acts promptly to provide protection against anginal pain, and has sustained efficacy that persists for 2 to 6 hours. Clinical investigations using serial treadmill testing in patients with angina demonstrate clinical effectiveness and bioactivity of BN beginning within minutes and lasting over 4 hours. The potential advantages of this preparation are discussed, and the formulation is compared to other available longacting nitrates. BN is an effective new addition to the nitrate armamentarium.

Angina Pectoris↗
PubMed1983

The tuberculin skin test in the diagnosis of tuberculous uveitis.

Of 18 patients (seven men and 11 women, ranging in age from 15 to 63 years) with presumed tuberculous uveitis seen between 1970 and 1982, 11 had intermediate-strength tuberculin skin test responses of less than 10 mm of induration. Similarly, nine had intermediate-strength responses of less than 5 mm of induration. Thus, any response of erythema or induration may be significant in the diagnosis of tuberculous uveitis and evidence enough for further testing with an isoniazid therapeutic trial.

Adolescent↗
PubMed1983

Phonocardiographic profile of the porcine bioprosthesis in the aortic position.

The phonocardiographic characteristics of the porcine bioprosthesis in the aortic position were evaluated in 24 asymptomatic patients. A medium to high frequency early systolic sound (AO) was present in 16 of 24 patients; abrupt "halting" of the stiff cusps of the porcine bioprosthesis during early left ventricular ejection seems to be the likely mechanism for the genesis of this sound. An unusually high amplitude aortic closing sound (AC) was present in all patients. A high frequency crescendo-decrescendo systolic murmur in early to mid systole was present in 22 patients. Possible mechanisms for the systolic murmur include: 1) altered resonating properties of the cusps, 2) functional bioprosthetic stenosis, and 3) the presence of a flexible stent. An early systolic opening sound preceding a short systolic murmur and a loud closing sound are common phonocardiographic findings of an uncomplicated porcine bioprosthesis in the aortic position. Therefore, absence of the aortic opening sound, alterations in the amplitude of the aortic closing sound, or an increase in the length of the systolic murmur may suggest bioprosthetic malfunction.

Adult↗
PubMed1983

A study of the diastolic flow velocity profile of the clinically uncomplicated mitral porcine bioprosthesis using an echo-Doppler technique.

Pulsed Doppler echocardiography was performed in 17 subjects who had clinically uncomplicated porcine bioprosthesis in the mitral position. A positive initial diastolic flow wave was present in all patients; end-diastolic A waves were seen in the sinus rhythm of every patient. The peak of the diastolic wave was delayed when compared with the normals in our laboratory. This wave had clearly demarcated ascending, mid- and descending segments. When contrasted with normal subjects, the slope of the diastolic wave was mildly reduced in all patients. Fine to coarse indentations on the descending and mid-segments were seen in 15/17 (88%) of the patients. We conclude that the diastolic flow profile of the clinically uncomplicated mitral bioprosthesis resembles mild mitral stenosis. Reduced orifice size and/or the physical properties of the bioprosthesis are the likely mechanisms for these alterations.

Adolescent↗
PubMed1982

The role of the isoniazid therapeutic test in tuberculous uveitis.

Of 38 cases of uveitis examined from 1970 to 1980 in which a tuberculous cause was considered, we classified 18 as presumed tuberculous on the basis of a positive response to isoniazid. We compared these patients to a control group who had a positive skin test but a negative response to the isoniazid therapeutic test. We found a family history of tuberculosis in seven of the 18 (P less than .05) and a more common (18 of 36 eyes) incidence of iridocyclitis (P less than .05) than of other types of uveitis. A uveitis patient who has a positive tuberculin skin test of any size or strength should undergo the isoniazid therapeutic test to ensure that a possible diagnosis of tuberculous uveitis is not missed. Tuberculosis should be suspected in both granulomatous and non granulomatous uveal lesions, especially in cases of chronic iridocyclitis.

Adult↗
PubMed1982

Superiority of two-dimensional echocardiography in the diagnosis of congenitally bicuspid aortic valve.

This study compares the role of M-mode and two-dimensional echocardiography in the evaluation of the nonstenotic, congenitally bicuspid aortic valve. Ten asymptomatic healthy subjects (age 20-35 years) with a systolic ejection click and short systolic murmur were evaluated. M-mode echocardiograms were entirely normal. The aortic root, diastolic closure line, eccentricity index of the aortic valve, and left ventricular size and function were normal in every subject. The two-dimensional parasternal long axis view of the aortic root was also normal in all patients with bicuspid aortic valves; there were no abnormalities of systolic excursion of the aortic cusps and doming of the aortic valve was absent. Images obtained in the two-dimensional parasternal short axis view of the aortic root at the level of the aortic valve revealed only two cusps, anterior and posterior, in all patients. The classic closure pattern of the normal tricuspid aortic valve forming a "Y" was absent in every subject. Instead, a horizontal closure line along the "X" axis was demonstrated in all patients; changing the angulation of the transducer in various positions did not alter this pattern. All subjects had increased reflectance of echoes along the line of diastolic closure, probably resulting from redundancy of the aortic cusp tissue. We conclude that because of the inability of the M-mode echocardiographic technique to accurately diagnose this condition in the study group, two-dimensional echocardiography should be the technique of choice in the evaluation of patients with a suspected bicuspid aortic valve. Recognition of this condition is important in view of its susceptibility to subacute bacterial endocarditis, aortic stenosis, and regurgitation.

Adult↗
PubMed1981

Affinity chromatography with 25-hydroxycholecalciferol ester in the isolation of the binding protein for vitamin D and its metabolites from human serum.

The 3 beta-hemisuccinate ester of 25-hydroxycholecalciferol was prepared by incubating the sterol with succinic acid anhydride in the presence of 4-dimethylaminopyridine at 4 degrees. The ester was isolated by silica gel column chromatography, and its hydrolysis in ethanolic sodium hydroxide yielded 25-hydroxycholecalciferol. The ester was covalently linked to aminoagarose in the presence of isobutylchloroformate, yielding 16 to 60 micrograms of sterol per packed ml of gel. Normal human serum was applied to the 3 beta-hemisuccinate-25-OH-D3 aminoagarose gel and elutions with buffer of increasing molarity were carried out. Total protein and DBP content of the 6M guanidine elution fractions revealed a 12 to 134-fold purification of human serum DBP by this technique. Best purifications were achieved by incubating serum with the gel at pH 8.3 and rinsing the gel with 0.3 M KCl prior to its elution with the guanidine. Our results indicate that affinity chromatography with this ligand, or possibly other vitamin D sterol esters, is a practical and useful technique in the analysis and preparative isolation of vitamin D sterol-binding proteins.

4-Aminopyridine↗
PubMed1981

Auscultation of the normally functioning prosthetic valve.

Before prosthetic function can be adequately assessed, physicians must be acquainted with the normal acoustic events associated with these devices. The auscultatory findings of the most commonly used devices--ball, disk, porcine, and bileaflet valves--are reviewed. The mechanisms of sound production and their timing are discussed.

Aortic Valve↗
PubMed1980

Nitrate tolerance and dependence. A critical assessment.

Tolerance and cross-tolerance to nitrates has been known since 1900 but the actual clinical importance of this phenomenon is unclear. Vasodilator treatment of congestive heart failure has provided an important new role for long-acting nitrates. The advent of high-dose nitrate regimens for both angina and heart failure raises the possibility that nitrate tolerance could be a potential detriment to therapy. A number of older studies have documented the development of tolerance and cross-tolerance to blood pressure and heart rate responses to nitrates as well as the rapid onset of tolerance to nitrate headaches in subjects given nitrates on a regular basis. Animal experiments also confirm the ready appearance of nitrate tachyphylaxis. Needleman has proposed a cellular mechanism for nitrate tolerance based on a chemical alteration of nitrate receptors in the vascular wall. In spite of these studies, there is considerable evidence that clinically relevant tolerance to nitrates is rare. Several recent investigations designed to look at this problem using high-dose isosorbide dinitrate (ISD) failed to demonstrate tachyphylaxis to the anti-anginal or hemodynamic effect of ISD. However, very recent work in patients with angina suggests that tolerance to high dose ISD does occur and may reduce the duration of action of long-acting nitrates. Overall, the bulk of current evidence does not support tolerance to be a major problem in nitrate treatment of cardiac diseases, although attenuated vasodilator responses may occur after several weeks of nitrate therapy.

Angina Pectoris↗