ISSN:0002-9629    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

Enhancement of the growth of a transplantable mammary adenocarcinoma in an Inbred strain of mice was produced by multiple subtherapeutic doses of 5- fluorouracil, 1 mg/kg/day. Marked inhibition of this same tumor occurred when larger doses, 15 mg/kg/day, of 5-fluorouracil were administered. The mechanism of the stimulating effect on tumor growth was dependent in part upon the number of tumor cells injected. With large inocula the growth-promoting effect of the drug was not observed. The possibility that this phenomenon was related to a modified immune response was investigated. Three groups of ten mice each were injected with bovine gamma globulin as the antigenic stimulus. The mice were treated with either a small subtherapeutic dose, 1 mg/kg/day, or a tumor-inhibiting dose, 15 mg/kg/day. A control group received only the antigen. Serum antibody levels were determined by hemagglutination and geometric mean titers were compared to the control animals given only antigen. There was a significant suppression of antibody response to bovine gamma globulin in animals treated with 1 mg/kg/day or 15mg/kg/day of 5-fluorouracil. The same dose that stimulated tumor growth was found to suppress the secondary antibody response to bovine gamma globulin.

ISSN:0002-9629    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

A relatively purified celMree system from rabbit reticulocytes Is described in which the various requirements (or enzymatic and nonenzyniatic formation of the initial ternary complex between messenger ribonucleic acid (mRNA). soluble ribonucleic acid (sRNA), and ribosomes were studied. A simple rapid method for preparing ribosomes which are relatively free of mRNA, sRNA, and enzymes is also presented and appears to be as good or better than similar procedures in current use. Utilizing this system it was found that deacylated-sRNA, N-acetyhaminoacyl-sRNA and chloramphenicol had no effect on the messenger specific binding of aminoacyl-sRNA to reticulocyte ribosomes. Chloramphenicol was also found to be without effect on the reassembly of polyribosomes in reticulocytes which had been preincubated with sodium fluoride. The inhibitory effect of chloramphenicol on mammalian cells, which has been shown in various other studies, must involve some other mechanism than that found in bacteria in which there is a direct inhibition of the initial steps in protein synthesis.

ISSN:0002-9629    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

Variant angina pectoris and persistent electrocardiographic changes consistent with a nontransmural myocardial Infarction occurred in a 53-year-old man whose coronary arteries were normal by selective cineanglography. The patient was subject to bouts of ventricular premature beats and a short run of ventricular tachycardia in association with his chest pain. Evidence is cited from the literature supporting the concept that spasm of a large coronary artery is the most likely explanation for this clinical syndrome. It is speculated that the persistence of electrocardiographic changes in patients with no demonstrable coronary artery disease may be related to the duration of the spasm.

ISSN:0002-9629    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

The nonspecific serum inhibitor of the hemagglutinin of rubella virus has been identified as a beta lipoprotein. Alpha or pre-beta lipoproteins or chylomicrons play no role In nonspecific antihemagglutination. Exposure of serum to either heparin or kaolin reduces the levels of the immunoglobulins; the latter, however, produces a greater effect. The studies presented In this paper indicate that treatment with a mixture of heparin and manganese chloride (MnCI,) is more effective than kaolin in removing the nonspecific antihemagglutinin from serum with low titers of specific anti-rubella antibody.

ISSN:0002-9629    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

A patient with clinically asymptomatic, chronic lymphocytic leukemia was found to display regular cycling ol his absolute peripheral lymphocyte counts which never exceeded subleukemic values Synchronous with the Inversion from rising to (ailing cell counts within a cycle, the transient appearance of a lymphotoxic serum factor could be demonstrated. The cytotoxic serum activity was heat-stable and independent from complement, and was still 91 per cent at a 1:25 dilution of the patient's serum when measured on the basis of ribonucleic acid (RNA) synthesis. In vitro experiments showed that the lymphotoxic factor in the patient's serum primarily inhibited protein and RNA synthesis and its stimulation by phylohemagglutinin in normal lymphocytes The preventive effect of the lymphotoxic factor on phytohemagglutinin stimulation was Instantaneous, whereas inhibition of RNA synthesis and decrease of cell viability occurred only after 40 hours of incubation. There was some evidence that/7) vivo the lymphotoxic factor predominantly affected the patient's leukemic cells rather than normal lymphocytes. Further abnormal findings in this patient were increasing serum levels of monoclonal immunoglobulin M (IgM) and the occurrence of varying proportions of lymphocytes with solitary cytoplasmic vacuoles in peripheral blood and bone marrow. Clinical and experimental findings led to the impression that the benign clinical course in this patient with chronic lymphocytic leukemia was, at least in part, the consequence of an immune mechanism resulting in some kind of tumor surveillance mediated by the effect of the lymphotoxic factor.

ISSN:0002-9629    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

A phenol-extracted ribonucleic acid (RNA) fraction of MS2 bacteriophage stimulates linear Incorporation of14C-amlno acids as Increasing amounts of RNA are added to a rabbit retlculocyte cell-free system. The pattern of14C-amlno acid uptake is consistently reproducible and significantly different from that directed by native rabbit reticulocyte messenger ribonucleoprotein (mRNP); it also clearly differs from the pattern resulting from endogenous synthesis in a system to which no messenger fraction has been added. Phage RNA-directed cell-free peptides have a predominant N-terminal alanine, as would be expected for MS2 coat protein and MS2 RNA polymerase, whereas the predominant N-terminal amino acid of reticulocyte mRNP peptides is valine, as would be expected for rabbit globln. This report supports the hypothesis that the ribosome is an undifferentiated particle which can translate from heterologous messenger RNA preparations.

ISSN:0002-9629    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

ß-Phenethylamines reacted with MgHPO1to form derivatives of NH.MgPO1in which an aralkyl group replaces an H (RNH1MgPO1). The per cent N1P1and Mg found by analysis agrees with such formulas. Histamine and serotonin gave only trace yields of similar compounds. L-epinephrine base reacted with MgATP that had been isolated from the reaction of free ATP (stripped of all metal ions) with Mg(OH)2. The epinephrine- MgATP complex was isolated and exhibited ultraviolet absorption and fluorescence spectra that were not seen with epinephrine or MgATP. The fluorescence peak was not obtained when epinephrine was added to the Mg complexes prepared from AMP and cyclic AMP. The absorbances indicate that Mg ligates with adenine in MgATP and that this bond is abolished by reaction with epinephrine through the catechol hydroxyls. Catecholamine-MgPO1contracted strips of rabbit aorta. Complexes of epinephrine with ATP and MgATP raised blood pressure in a rat. The existence of such complexes in vivo and their biological significance may become more certain after further studies in stoichiometry and dissociation and with enzymes.

ISSN:0002-9629    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

The exponential proliferation of the medical literatures has been likened to a malignant or communicable disease process. Thus the theory of epidemics has been applied to the transmission of ideas Recently, a 4-factorial epidemiological model, schistosomiasis, has been characterized mathematically by modification of the Kermack- McKendrick theory. This model has been found to be uniquely adaptable to the transmission of information via the literatures, the author being the definitive host, the manuscript the infective embryo, the Journal analogous to the snail, and the published paper the larva infective for man. An attempt to examine this ecological cycle has been made by the investigation of several medical literatures Their previously described exponential growth was obvious, but as the paperauthor ratio remained constant with time, it was not, as it has been popularly labeled, a “literature explosion”; it was a “population explosion.” Furthermore, the investigation revealed that the number of authors correlated closely with the number of different journals in a field, and, most important, that the ratio between the total published papers and those of quality was also constant with time. It is suggested, therefore, that any drastic alteration of the ecology of the medical literatures might result in the destruction of quality along with quantity. Protection of the reader might be achieved by reducing exposure to the entire literature and increasing exposure to literature of quality.

ISSN:0002-9629    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

The therapy of patients with hemorrhagic diseases, particularly hemophilia, has undergone dramatic change during the past decade. The availability of concentrated factor VIII preparations has provided us with the opportunity to undertake elective surgical procedures and to experiment with outpatient therapy. The past therapy of hemophilia is briefly reviewed, the management of hemophilia in the present era is summarized, and the detection of the carrier state and the potential for more definitive permanent therapy for hemophilia in the future are discussed.

ISSN:0002-9629    

出版商:OVID    

年代:1972

数据来源: OVID