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Biomedical subjects

G Kramer

Publications and source records attributed to G Kramer.

At least 199 records · Page 11Linked to original sources
PubMed1979

No effect of cAMP on protein synthesis in reticulocyte lysates.

The results of a series of experiments are interpreted to indicate that protein synthesis in reticulocyte lysates is not affected by the reticulocyte cAMP-dependent protein kinase. The catalytic subunit of this enzyme was isolated to apparent homogeneity. Also, the protein inhibitor of this protein kinase was isolated from muscle. Neither physiological concentrations of cAMP nor any of these protein components had a detectable effect on protein synthesis in reticulocyte lysates in the presence or absence of exogenous heme. Phosphorylation of the smallest subunit of eukaryotic initiation factor 2 or the 90,000 to 100,000-dalton peptide associated with eukaryotic initiation factor 2 kinase activity were not affected by the activity of the cAMP-dependent protein kinase under conditions in which exogenous heme has a pronounced effect on these reactions.

Animals↗
PubMed1979

Effects of local anesthesia on gingival cAMP levels.

The basal levels of cAMP in the attached gingiva of Rhesus monkeys and the changes in tissue cAMP levels produced by infiltration anesthesia with lidocaine and lidocaine containing 1:100,000 epinephrine were studied. The basal level of cAMP in uninjected monkey gingiva ranged from 12 to 20 picomoles of cAMP per mg of gingival protein. This level was 75 times greater than the cAMP content of monkey blood plasma. Infiltration of the attached gingiva with saline or plain lidocaine for 5 minutes did not produce any significant changes in tissue cAMP levels. Infiltration of the gingiva with lidocaine containing 1:100,000 epinephrine, on the other hand, caused a very marked increase in tissue cAMP levels. Thirty seconds after infiltration with lidocaine with 1:100,000 epinephrine there was a 250% increase in cAMP content of the anesthetized tissue versus the uninjected control tissues. The maximal increase in tissue cAMP levels was observed 5 minutes after infiltration when the cAMP content of the gingiva was 1000 to 1100% above the control level. It is proposed that regulation of tissue cAMP levels by epinephrine or other agents may prove of therapeutic usefulness in regulating inflammation and healing of tissues after surgery or other trauma.

Anesthesia, Dental↗
PubMed1979

[Operative risk in very old patients (author's transl)].

Patients more than 75 years of age will tolerate surgery with good results under the following conditions: 1) Metabolic deficiencies have to be compensated prior to surgery - 2) Preoperative preparatory treatment should be completed at least 3 days before surgery - 3) After surgery has been performed acid-base balance, haemoglobin, protein metabolism and renal function should be watched strictly - 4) Ambulation of the patient and social care should start on the very first day after surgery.

Acid-Base Imbalance↗
PubMed1978

GTP hydrolysis during methionyl-tRNAf binding to 40 S ribosomal subunits and the site of edeine inhibition.

Three lines of evidence are presented indicating that GTP hydrolysis associated with eukaryotic peptide initiation occurs in the absence of 60 S subunits when methionyl-tRNAf is bound to 40 S ribosomal subunits. An enzyme fraction required for binding of methionyl-tRNAf to 40 S subunits and peptide initiation, tentatively equated with eIF-(4 + 5), has GTPase activity and appears to be responsible for hydrolysis of GTP in the methionyl-tRNAf.eIF-2.GTP complex. Direct analysis of the methionyl-tRNAf.40 S complex formed with with eIF-2 and [8-3H] guanine, [gamma-32P]GTP reveals bound guanine but not gamma-phosphate. Edeine, a peptide antibiotic containing spermidine and beta-tyrosine residues at its COOH terminus and NH2 terminus, respectively, blocks peptide initiation and interferes with binding of methionyl-tRNAf to 40 S ribosomal subunits. Inhibition of binding is observed when the eIF-2-mediated binding reaction is carried out with GTP but not with guanosine 5'-(beta,gamma-methylene)triphosphate or guanosine 5'-(beta,gamma-imido)triphosphate. Edeine was labeled by iodination and shown to bind with high affinity to 40 S but not to 60 S ribosomal subunits. It is suggested that edeine blocks a specific site on the 40 S ribosomal subunit to which a segment of the methionyl-tRNAf molecule is bound during the course of the initiation reaction sequence.

Animals↗
PubMed1978

[Image intensifiers in Osteosynthesis a danger for the team? (author's transl)].

Three years' examination of X-ray load when working with the X-ray image intensifier have led to the conclusion that with a tolerance basis of 100 mrem per week a fluoroscoping time of about 1 hour is tolerable without lead protection with an average fluoroscoping time of 5 minutes for one osteosynthesis. The operating surgeon can carry out about 10 osteosyntheses per week. For the other members of the operating team the X-ray load is significantly lower and, therefore, there are no limits in practice. It must be noted that an exact record of the fluoroscoping time and dose measurements is absolutely necessary.

Female↗
PubMed1977

Partial purification and characterization of a translational inhibitor from Friend leukemia cells.

A translational inhibitor has been isolated from unstimulated Friend leukemia cells. The inhibitor is a heat-labile, sulfhydryl reagent-insensitive protein with a molecular weight of approximately 214,000. It inhibits protein synthesis at a step of peptide chain initiation by preventing initiation factor-dependent binding of methionyl-tRNAf to 40 S ribosomal subunits. However, it does not interfere with the formation of the ribosome-independent ternary complex between the initiation factor IF-E2, methionyl-tRNAf, and GTP. The inhibitor preparation contains protein kinase activity which phosphorylates the smallest subunit of IF-E2. There appears to be a functional similarity between this inhibitor from Friend leukemia cells and the hemin-controlled repressor from reticulocytes.

Animals↗
PubMed1977

[Serological and histological investigations as well as studies on changed food uptake during adrenaline application by intraperitoneal depot capsule].

The authors have developed a method for long-term permanent application of water soluble substances by a intraperitoneal depot capsule [KLINGENBERG et al., Exp. Path. 13, 302-311 (1977)]. The present study deals with the effects on the liver and several metabolic processes induced by continuous long-term adrenaline application by means of such a depot capsule.

Animals↗
PubMed1977

Partial reaction of peptide initiation inhibited by phosphorylation of either initiation factor eIF-2 or 40S ribosomal proteins.

Preparations of the hemin-controlled repressor (HCR) from rabbit reticulocytes contain 3':5'-cyclic-AMP-independent protein kinase activity for the smallest subunit of the peptide initiation factor eIF-2 and for proteins of reticulocyte 40S ribosomal subunits. Binding of the ternary complex formed between Met-tRNAf, GTP, and eIF-2 to 40S ribosomal subunits is shown to be inhibited by phosphorylation of either the ribosomal subunits or eIF-2. The protein kinase activity responsible for phosphorylation of eIF-2 has been separated from the activity for phosphorylation of 40S ribosomal subunits and shown to independently block the same partial reaction of peptide initiation. It appears that different enzymes are involved, each capable of regulating peptide initiation at the same step but by a different mechanism.

Animals↗
PubMed1977

[Adrenaline application by intraperitoneal depot capsule -- effects in the heart (author's transl)].

An intraperitoneal depot capsule was developed to improve the hitherto used in vivo test methods for chronic action of water soluble substances (repeated injections or permanent infusion which immobilizes the experimental animals). The capsule allows free movement of the animal and guarantees long-term continuous output of the substance. The effectiveness of the capsule was examined using adrenaline as test substance. In these experiments the maximum period of effectiveness and the consequences of permanent occupation of the receptors due to continued supply of adrenaline were studied.

Animals↗
PubMed1976

Separate pyrimidine-nucleotide pools for messenger-RNA and ribosomal-RNA synthesis in HeLa S3 cells.

Kinetic analyses of mRNA and 28-S RNA labeling [3H]uridine revealed distinctly different steady-state specific radioactivities finally reached for uridine in mRNA and 28-S RNA when exogenous [3H]uridine was kept constant for several cell doubling times. While the steady-state label of (total) UTP and of uridine in mRNA responded to the same extent to a suppression of pyrimidine synthesis de novo by high uridine concentrations in the culture medium, uridine in 28-S RNA was scarcely influenced. Similar findings were obtained with respect to labeling of cytidine in the various RNA species due to an equilibration of UTP with CTP [5-3H]Uridine is also incorporated into deoxycytidine of DNA, presumably via dCTP. The specific radioactivity of this nucleosidase attained the same steady-state value as UTP, uridine in mRNA and cytidine in mRNA. The data indicate the existence of two pyrimidine nucleotide pools. One is a large, general UTP pool comprising the bulk of the cellular UTP and serving nucleoplasmic nucleic acid formation (uridine and cytidine in mRNA, deoxycytidine in DNA). Its replenishment by de novo synthesis can be suppressed completely by exogenous uridine above 100 muM concentrations. A second, very small UTP (and CTP) pool with a high turnover provides most of the precursors for nucleolar RNA formation (rRNA). This pool is not subject to feedback inhibition by extracellular uridine to an appreciable extent. Determinations of (total) UTP turnover also show that the bulk of cellular RNA (rRNA) cannot be derived from the large UTP pool.

Cell Division↗
PubMed1976

Specificity of the protein kinase activity associated with the hemin-controlled repressor of rabbit reticulocyte.

Highly purified preparations of hemin-controlled repressor of rabbit reticulocyte contain a 3':5'-cyclic AMP-indenpendent protein kinase activity that phosphorylates the low-molecular-weight (about 38,000) polypeptide chain of the initiation factor that forms a ternary complex with GTP and Met-tRNAf. These preparations also phosphorylate several polypeptide components of reticulocyte 40S ribosomal subunits. However, no significant levels of phosphorylation are observed when casein, histones, Artemia salina 40S ribosomal subunits, or other initiation factor fractions are used as substrates although high levels of phosphorylation are obtained with cruder preparations of the repressor. An antibody to these highly purified preparations of repressor has been obtained from the serum of immunized goats. Preincubation with immune goat IgG results in the neutralization of the inhibitory activity of the repressor, while normal IgG has no effect. Preincubation with immune IgG also abolishes the protein kinase activity responsible for the phosphorylation of the initiation factor and reticulocyte 40S subunits. Histone phosphorylation by crude repressor preparations, on the other hand, is unaffected by preincubation with immune IgG.

Animals↗