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Biomedical subjects

E Rapaport

Publications and source records attributed to E Rapaport.

At least 127 records · Page 7Linked to original sources
PubMed1976

Duration of hospitalization in "uncomplicated completed acute myocardial infarction". An Ad Hoc Committee review.

The clinical and laboratory findings diagnostic of acute myocardial infarction include at least two of the following: (1) a history of pain consistent with myocardial ischemia, (2) electorcardiographic findings consistent with infarction, and (3) a rise in the serum level of specific cardiac enzymes. By the 4th or 5th day of illness, specific criteria can be applied to assign certain patients to a subset with "uncomplicated completed acute myocardial infarction." These criteria include the absence of evidence of (1) continuing cardiac ischemia, (2) left ventricular failure, (3) shock, (4) important cardiac arrhythmias, (5) conduction disturbances, and (6) other serious illnesses in patients with an established acute myocardial infarction. In terms of prognosis and management, patients in this subset should be regarded as substantively different from patients in other subsets. They should respond favorably to short periods of immobilization and hospitalization than those generally used. They may remain at bed rest (modified in regard to sitting and the use of a commode) for 4 days. Subsequently, mobilization with a program of progressive activity over the ensuing 5 to 10 days should reduce the duration of hospitalization to less than the current average of 17.5 to 20.8 days for patients with acute myocardial infarction. Nine to 14 days should suffice in most instances. Current and future trials may indicate that still earlier mobilization and shorter hospitalization periods can be applied to certain patient groups, but the evidence on this point is incomplete. For the individual patient, many factors will determine the optimal duration of bed rest and hospital stay. The patient's physician must consider the therapeutic benefits that may attend earlier mobilization and shorter hospitalization while weighing potential disadvantages. When the responsible physician does not regularly care for the patient, consultation with an experienced cardiologist is desirable. Patients whose condition is classified as "uncomplicated" may manifest deterioration during their illness and require assignment to a subset with a different prognosis and requiring different forms of treatment. For patients with uncomplicated acute myocardial infarction, as well as those in other subsets, absolute rules for therapy are unwise and application of broader principles by the alert physician is more likely to be beneficial.

Arrhythmias, Cardiac↗
PubMed1976

Presence of diadenosine 5',5''' -P1, P4-tetraphosphate (Ap4A) in mamalian cells in levels varying widely with proliferative activity of the tissue: a possible positive "pleiotypic activator".

An accurate assay of diadenosine 5',5'''- P1,P4-tetraphosphate [A(5') pppp(5')A], which was shown to be formed in vitro in the backreaction of the amino acid activation step, has been developed in various cell lines in culture and in normal mouse liver or hepatoma in vivo. Use of radioactive labeling of acid-soluble nucleotides to high specific activity followed by chromatographic separation techniques yielded levels of Ap4A varying from 5 to 0.05 muM (from 30 pmol/mg of protein to 0.15 pmol), depending on the doubling time of the cell line or the proliferative state of the cells. The levels of Ap4A incells is inversely related to their doubling time, varying from 0.1 X 10(-4) of the cellular ATP levels in slowly growing cells to 20 X 10(-4) of the ATP levels of cells with rapid doubling times. The steady-state levels of ATP of different cell lines, although showing some fluctuations, are not related to the doubling time of the cells. Arrest of cellular proliferation by serum deprivation or amino acid starvation, which does not alter the cellular ATP levels more than 2-fold, does nevertheless cause a decrease of 30 to 50-fold in the Ap4A levels. Inhibition of protein synthesis by pactamycin or puromycin, or inhibition of DNA synthesis by hydroxyurea, leads to a more dramatic decrease of 50 to 100-fold in intracellular Ap4A levels. The metabolic lability of Ap4A is also demonstrated by its rapid depletion after decreases in the ATP/ADP ratio. The possibility of Ap4A being a metabolic "signal nucleotide" that is formed at the onset of protein synthesis and is active in positive growth regulation (positive pleiotypic activation) is discussed.

Adenine Nucleotides↗
PubMed1976

Incorporation of adenosine into ATP: formation of compartmentalized ATP.

The incorporation of [3H]adenosine, [3H]adenine, and [3H]hypoxanthine into adenine nucleotides of nude (athymic) mouse liver and human hepatoma grown subcutaneously in nude mice was studied. 3H and 32P radioactive labeling in vivo of acid-soluble nucleotides followed by chromatographic procedures indicated that, in contrast to [3H]adenine and [3H]hypoxanthine, [3H]adenosine is preferentially incorporated into ATP in comparison with its incorporation into AMP and ADP. This phenomenon, as well as complementing the recently reported 3-fold increase in total cellular ATP upon treatmen- with 0.5-1.0 mM concentrations of adenosine, indicates the formation from adenosine of compartmentalized ATP that is not produced from either adenine or hypoxanthine. The observed effect is of larger magnitude in the growth-arrested normal liver than in the actively growing tumor.

Adenine↗
PubMed1975

Natural history of aortic and mitral valve disease.

An appreciation of the natural history of acquired valvular heart disease is a prerequisite to an understanding of how surgical intervention has altered the natural outlook. The prognosis for a patient with valvular heart disease treated medically is dependent on the stage of the disease at which he is first seen. Therefore, assessment for surgery requires evaluation of the pathophysiologic consequences that have resulted from the hemodynamic alterations. Survival statistics for patients seen at the University of California Medical Center at San Francisco are presented and compared with the data of others. Stenotic lesions appear to have a poorer prognosis than chronic regurgitant lesions and generally warrant surgical intervention at an earlier functional stage of the disease. However, valvular insufficiency produced acutely is poorly tolerated and many constitute a surgical emergency.

Aortic Valve↗
PubMed1975

A new chemical procedure for 32P-labeling of ribonucleic acids at their 5'-ends after isolation.

A new technique, which utilizes the chemical reaction between [32P]diimidazolidate of orthophosphate and the cetyltrimethylammonium salt of high-molecular-weight RNA in nonaqueous dimethyl formamide, has been developed for the 32P-labeling of RNAs after isolation. The radioactive label of high specific activity is introduced onto a phosphorylated 5'-end of the RNA and renders it suitable for 5'-terminal group analysis. When the labeling reaction was applied to the 70S RNA of avian myeloblastosis virus, a labeled 35S RNA was isolated on sucrose-dimethyl sulfoxide gradients without apparent degradation.

Avian Myeloblastosis Virus↗
PubMed1975

Relationship of the first step in protein synthesis to ppGpp: formation of A(5')ppp(5')Gpp.

In the presence of purified Escherichia coli lysyl-tRNA synthetase [L-lysine:tRNALys ligase (AMP-forming) EC 6.1.1.6], L-lysine, and ATP, addition of the nucleotide ppGpp results in formation of a unique product-A(5')ppp(5') Gpp. The same compound is also formed very rapidly in a cell-free protein-synthesizing system when ppGpp is added. The possible significance of this reaction in the rapid turnover of ppGpp and as a more general mechanism by which an AMP residue is activated and introduced onto a 5'-diphosphorylated species, including the 5'-end of an RNA, is further discussed.

Adenine Nucleotides↗
PubMed1975

The fractional disappearance rate of the separate isoenzymes of creatine phosphokinase in the dog.

Separation of creatine phosphokinase (CPK) isoenzymes from canine tissue was accomplished successfully with column chromatography. Intravenous injection of each isoenzyme into six dogs resulted in a mono-exponential loss with differing fractional disappearance rates with averaged 0.65%, 0.86%, and 1.68%/min for the MM, MB, and BB isoenzymes, respectively. The distribution volume also varied: MM averaged 6.7%/body weight, MB 7.8%, and BB 10.4%.

Animals↗