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Biomedical subjects

E Fischer

Publications and source records attributed to E Fischer.

At least 217 records · Page 12Linked to original sources
PubMed1982

The elongation factor Tu binds aminoacyl-tRNA in the presence of GDP.

Escherichia coli elongation factor (EF-Tu) binds aminoacyl-tRNAs (aa-tRNA) not only in the presence of GTP but also in the presence of GDP. Complex formation leads to a protection of the aa-tRNA against nonenzymatic deacylation and digestion by pancreatic ribonuclease, as well as to a protection of EF-Tu against proteolysis by trypsin. The equilibrium constant for the binding of Phe-tRNAPheyeast for example to EF-Tu.GDP has been determined to be 0.7 X 10(5) M-1 which is 2 orders of magnitude lower than the equilibrium constant for Phe-tRNAPheyeast binding to EF-Tu.GTP. In the presence of kirromycin, aminoacyl-tRNA binding to EF-Tu.GDP is not affected as much: Phe-tRNAPheyeast is bound with an equilibrium constant of 3 X 10(5) M-1. While there is also a measurable interaction between EF-Tu.GTP and tRNA, such an interaction cannot be detected with EF-Tu.GDP and tRNA, not even at millimolar concentrations. A so far undetected complex formation between aminoacyl-tRNA and EF-Tu.GTP in the presence of pulvomycin, however, could be detected. The results are discussed in terms of the structural requirements of ternary complex formation and in the light of proofreading schemes involving A-site binding on the E. coli ribosome.

Escherichia coli↗
PubMed1982

[Significance of vasodilator agents in the treatment of heart insufficiency].

Although the use of vasodilators acting on veins and arterioles to treat patients with refractory congestive heart failure has become increasingly widespread, essential problems relating to the clinical efficacy of long-term therapy remain to be solved. The pathophysiological bases of the most common forms of heart failure are discussed and the spectrum of available drugs and their principal mechanism of action are categorized. In addition, a possible conceptual approach to ambulatory oral vasodilator treatment is outlined.

Edema↗
PubMed1982

Xeroderma pigmentosum patients from Germany: clinical symptoms and DNA repair characteristics.

Dermatologic, ophthalmologic, and neurologic examinations were carried out on 33 patients with clinical symptoms of xeroderma pigmentosum (XP). Complementation groups were determined for 23 patients. Types of tumors and complementation group were found to be related in the following way: In the XP variant groups basaliomas were the most frequently occurring malignant tumors, whereas in the D group pigmentary tumors, such as melanotic precanceroses and melanomas prevailed; in the A and the C group, spinaliomas seem to be the most frequent malignomas. The DNA repair activity was measured using colony-forming ability and unscheduled DNA synthesis. Colony-forming ability was quantitated as a function of 12 different UV doses and expressed in terms of D0. Unscheduled DNA synthesis was determined autoradiographically by establishing dose-response curves, which were analyzed by the characteristic value of linear regression. G0, defined as the linear increase in the mean number of silver grains per nucleus when the UV dose is multiplied by the factor of e (i.e., 2.72), was derived from the slopes of the regression lines. The repair capability of XP fibroblast lines was classified on the basis of D0 and G0.

Adolescent↗
PubMed1982

Nitrogen sparing effects and mechanisms of branched-chain amino acids in the injured rat.

A series of experiments in a rat injury model were designed to elucidate the role and mechanisms of branched-chain amino acids in the post-injury catabolism. Our results suggest that: 1. Nutritional support can maintain nitrogen equilibrium in the early post-operative state. 2. Branched chain amino acids exert a nitrogen sparing effect and thus prevent or minimise post-operative catabolism. 3. Increasing the amount of infused branched chain amino acids results in nitrogen retention. 4. A balanced amino-acid mixture containing 45 per cent branched chain amino acids seems to be optimal for nutritional support in the post-injury state.

Journal Article↗
PubMed1982

[Acro-osteosclerosis of the fingers, a normal sex- and age-dependent endosteal reaction].

Acro-osteosclerosis (AOS) of the distal phalanges was estimated in a semi-quantitative manner in a sample of patients with polyarthritis and compared with a sample of non-rheumatic patients, corresponding in age and sex incidence. AOS must be regarded as a normal endosteal process which occurs particularly in women; it begins in early adult life and regresses with old age. There was no relationship between AOS and chronic polyarthritis; nevertheless, the bone 'terrain' in chronic polyarthritis is not identical with that in normals.

Adult↗
PubMed1982

[Hereditary complement deficiencies].

Complement deficiencies of all nine C-components have been observed. Hereditary defects of early components of the classical pathway - C1, C4, C2 - are often associated with diseases of the immuncomplex-type especially with systemic lupus erythematosus, dermatomysitis, vasculitis and nephritis. Deficiencies of C3 and C3b inactivator are linked to severe and recurrent bacterial infections. Patients with hereditary defects of the so-called late components, C5-C9, show increased susceptibility to recurrent disseminated infections by neisseria gonorrhoeae and meningitidis. The most frequent of the defects of the complement system is the hereditary deficiency of C1-inactivator which is associated with hereditary angioneurotic edema. In this paper the C-defects and their genetics are described and possible pathomechanisms are discussed.

Complement Activating Enzymes↗
PubMed1982

[How long do dermatophytes survive in the water of indoor pools?].

Trichophyton rubrum, Trichophyton mentagrophytes and Candida albicans were shown to survive at least 123 days in chlorinated swimming-pool water of 28-30 degrees, at least 18 days in ozonized water at 34-35 degrees, and at least 25 days in pipe water at room temperature of 23-25 degrees. Concentrations of chlorine and ozone normally used to inhibit bacterial contamination did not devitalize the fungi used in the experiment.

Arthrodermataceae↗
PubMed1982

Effect of bile acids on the biliary excretion of amaranth and the respiration of liver mitochondria.

The effects of lithocholic acid (LCA), chenodeoxycholic acid (CDCA), deoxycholic acid (DOCA), cholic acid (CA) and dehydrocholic acid (DHCA) on the biliary excretion of amaranth (AM) in rats and on the respiration of isolated liver mitochondria were investigated. Bile acids diminished the biliary excretion of AM, and in vitro they enhanced the state 4 mitochondrial respiration and inhibited DNP- and ADP-stimulated oxygen consumption. The ID50 values (mumol/kg i.v.) and I50 concentrations (X 10(-5) M) of the bile acids for inhibiting AM excretion and ADP-stimulated mitochondrial respiration, respectively, were as follows: for LCA 16 and 3.3, for CDCA 160 and 24, for DOCA 230 and 31, for CA 680 and 105, and for DHCA 700 and 260. LCA, CDCA and DOCA inhibited the biliary excretion of AM uncompetitively. It is concluded that the toxic effect of LCA, CDCA and DOCA on mitochondria might play a role in their inhibitory action on the biliary transport of AM.

Amaranth Dye↗
PubMed1981

[Lactobacillus casei endocarditis after aortic valve prosthesis].

A report is presented on a 53-year-old patient with endocarditis caused by Lactobacillus casei 9 years after prosthetic replacement of the aortic valve with a Björk-Shiley graft. In spite of a delay of about 6 weeks before therapy was started (due to difficulties in identifying the causative agent), treatment with a combination of penicillin G and gentamicin was effective and replacement of the artificial valve was not necessary. Seven months after cessation of therapy the patient is still free of symptoms. No other report of conservatively managed endocarditis due to lactobacilli and involving a prosthetic valve was found in the literature accessible to our group.

Anticoagulants↗
PubMed1981

Modulation of the formation of the human C-3 amplification convertase of complement by polyelectrolytes.

Heparin in the fluid phase inhibits generation of the C3 amplification convertase of complement C3b,Bb. The anticomplementary activity requires the presence of O-sulfate groups on the molecule and is suppressed when the negative charges of heparin are neutralized with positive charges on polycations. In the absence of heparin, polycations inhibit generation of the cell-bound or fluid phase amplification convertase at final concentrations of 1 to 2 x 10(-8) M for poly-L- lysine 50,000 (PLL). PLL is more active on the D-dependent convertase C3b,Bb than in preventing generation of C3b,B; it does not alter the stabilizing effect of properdin. As for heparin, the major site of the inhibitory action of polycations is on the binding capacity of C3b for B. The low affinity interaction of C3b and B is a privileged site for potential pharmacologic modulation of the amplification convertase of complement by polyelectrolytes.

Binding Sites↗
PubMed1981

The role and functions assumed by a department of community medicine in planning a group practice.

This paper describes the technical assistance role and the functions assumed by the Department of Community Medicine of the Mount Sinai School of Medicine in a planning process that led to the development of a group practice in the Department of Medicine of the Mount Sinai Hospital. Three distinct phases are identified in the process: how the planning was planned, how the plan was prepared, and how the implementation was planned. The role of Community Medicine in each phase is analyzed.

Community Medicine↗
PubMed1981

Schizophrenia: a network crisis.

The results of a study comparing the structure and function of the social networks of a group of first-admission schizophrenics with those of a group of multiple-admission schizophrenics are presented. Structurally, the networks of the first-admission patients are larger and more interconnected. Functionally, their networks have a greater percentage of multiplex and nondependent links. On the basis of these data, it is concluded that the most dramatic changes in social networks develop after the patient's first hospitalization. The dissolution of the patient's network is attributed to the antagonistic attitudes and reactions of those close to the patient, as well as to the patient's impaired social competence. Schizophrenia seemingly is a network crisis not only for the individual but for the network as a whole. It is suggested that active intervention at the time of the first psychotic episode may be helpful in avoiding network collapse and the patient's resultant social isolation.

Adolescent↗