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C Giunta

Publications and source records attributed to C Giunta.

At least 55 records · Page 3Linked to original sources
PubMed1988

Distribution of methicillin-resistance and of protein A among Staphylococcus aureus strains isolated from different hosts.

The link between loss of protein A and methicillin-resistance, and the presence of both characters in relation to the hosts from which S. aureus strains have been isolated, was examined. The majority of methicillin-resistant strains lost protein A. Normal hosts were generally infected with methicillin-sensitive protein A positive strains, while in immunocompromised patients the finding of multiresistant-protein A deficient strains was more frequent. The importance of the host's immune system, together with the antibiotic pressure in selecting these mutants, is discussed.

Humans↗
PubMed1986

Enzymatic characterization of Staphylococcus aureus strains: a possible role of habitat and methicillin-resistance in the determination of the differences observed.

Twenty five strains of Staphylococcus aureus of human and environmental origin were tested for their enzymatic patterns. All human strains possessed acid phosphatase, while only 25% of the environmental staphylococci demonstrated acid phosphatase activity. In addition, the enzyme alpha-glucosidase was present only in the methicillin resistant-multiresistant strains, in spite of their origin. This work suggests a possible role of the enzyme on penicillin-binding protein mediated methicillin-resistance and stresses the importance of external habitat in the expression of enzymatic activity of bacteria. The enzymatic pattern may confirm or exclude cross-infection, when a single species, with uniformly antibiotic responses, is involved.

Acid Phosphatase↗
PubMed1985

Activatory effect of two cardioglycosides on Cavia cobaya kidney Na+/K+-ATPase activity.

Ouabain and K-strophanthoside promote an enhancement of Na+/K+-ATPase activity in a range of cardioglycoside concentrations from 100 nM to 100 pM, with a maximum (+30%) between 10 and 4 nM. Binding experiments with [3H]ouabain show upward-curved Scatchard plots and evidence two intrinsic affinity constants for the ligand: (a) High-affinity constant: 350 nM (microsomes) and 15 nM (purified enzyme). (b) Low-affinity constant: 2100 nM (microsomes) and 890 nM (purified enzyme). The reaction velocity trend indicates that at ouabain concentrations higher than 20 nM but lower than the minimal inhibiting level, the enhanced reaction velocity is tending towards the control values.

Animals↗
PubMed1984

Solubilization and purification of Na, K-ATPase from the outer medulla of rabbit kidney.

There is great interest in the histologic localization of the Na, K-pump in various tissues: histochemical methods in this case work poorly, so a specific antibody against a purified soluble Na, K-ATPase is necessary. We approached this problem with a two-step ionic detergent treatment; the separation of the solubilized enzyme was attempted by gel filtration and ion-exchange chromatography. The gel filtration purified form was active and nearly pure, while the ion-exchange on was purer but inactive. PAGE analyses of the various enzyme forms are presented.

Animals↗
PubMed1984

Na+/K+-ATPase from Xenopus laevis (Daudin) kidney and epidermis: high sensitivity towards regulatory compounds.

Na+/K+-ATPase was prepared from Xenopus laevis epidermis. Purification was obtained by ultracentrifugation on sucrose discontinuous gradient. The maximum of enzyme-containing membranes was concentrated in the denser sucrose layer, exhibiting a good and long-lasting activity (specific activity about 55 mumoles of ATP hydrolyzed/mg of protein/hour). The Kd for the ouabain of kidney and epidermis enzymes were very low (in purified preparations respectively 16 nM for kidney enzyme and 4 nM for skin enzyme), indicating a very high sensitivity toward the cardioglycoside. The dose-response graphs of kidney and skin Na+/K+-ATPase vs ouabain concentrations show that at ouabain concentrations ranging from 1 nM and 1 pM the inhibition elicited by the cardioglycoside disappears and is replaced by an activatory effect. At cardioglycoside concentrations higher than 1 nM, the graphs show the typical inhibition curve.

Animals↗
PubMed1983

[The use of glucagon in cholangiography].

Certainty of interpretation can be hindered by spasms of the sphincter of Oddi during cholangiography, since these impair the opaqueness of the image of the distal common duct and reduce the bile flow in the duodenum. Recently, especially in the English-speaking world, glucagon has been used to relax the bile ducts. The authors, following this line of experimentation, report on the use of glucagon in intravenous cholangiographic examination (15 cases), in postoperatory cholangiography (3) and in intra-operatory cholangiography (7), for a total of 25 patients, 13 of whom affected with pathological bile-duct conditions. In each type of examination, after the contrast material had been administered, X-rays were taken in the same position before and three or four minutes after the endovenous injection of glucagon. In every case glucagon revealed its intense hypotoning action, a consistent and rapid effect of short duration, the absence of side effects, the possibility of its use in every type of cholangiographic examination and its effectiveness in controlling the degree of diagnostic uncertainty.

Cholangiography↗
PubMed1982

Sodium, and potassium dependent adenosinetriphosphatase from Cavia cobaya kidney: interaction with very low cardiotonic steroid concentrations.

We noticed that very low cardiotonic steroid concentrations activate the Na, K-ATPase in a variety of different preparations. In the present research the effect of three cardioactive steroids on the enzymatic activity was tested. The glycosides activated the Na,K-ATPase, while the aglycone strophantidine does not. Ouabain binding studies on various preparations showed the presence of two binding site classes with different affinities. Purification procedures shift the apparent Kd values, while K+ increase them. Accordingly, the activatory and inhibitory effects may be explained by the cardiotonic steroid binding on different sites of the Na,K-ATPase molecule.

Animals↗
PubMed1982

Na,K-ATPase from Xenopus laevis kidney and epidermis: ouabain interaction studies.

A satisfactory purification from Xenopus laevis epidermis is presented. Ki and Kd values for the ouabain-enzyme interaction have been evaluated. Both parameters appear very low, as compared with those demonstrated in other anurans. Very low digitalis-like compound level was demonstrated in Xenopus; on the contrary in Bufo, in which these substances play a defensive role, it is very high. Our results strengthen the hypothesis of a physiological action of such compounds in regulating enzyme-driven Na+/K+ exchanges.

Animals↗
PubMed1980

Characterization of Na+/K+-ATPase from Xenopus laevis kidney. Preliminary results.

In Xenopus laevis, the renal Na+/K+-dependent ATPase is a very important enzyme involved in osmoregulatory processes and active transport. The enzyme was obtained from a microsome fraction purified by sucrose discontinuous gradient (10%, 15%, 29.4%) ultracentrifugation after SDS treatment, and concentrated in the denser layer. The assayed biochemical parameters and their values are: 1) Km (ATP): 0.24 mM; 2) K1/2 (Na+): 20.6 mM; 3) K1/2 (K+) 1.6 mM; 4) Ki (ouabain): 0.025 micrometer; 5) optimum pH: 7.2; 6) optimum temperature:" two peaks at 37 degrees C and 45 degrees C.

Adenosine Triphosphate↗
PubMed1979

Na+/K+-dependent adenosinetriphosphatase in rabbit kidney. Separation by affinity chromatography.

We attempted separations by affinity chromatography of the Na+/K+-dependent adenosinetriphosphatase, using Sepharose 6B covalently coupled with ouabain, either on microsomal fractions or on preparations purified by discontinuous sucrose density gradient ultracentrifugation. The material, specifically eluted with ouabain, was tested to evaluate the recovery of ATPase activity and ouabain binding capacity. The results have shown the efficiency of this technique for (Na+/K+)-APTase isolation.

Animals↗
PubMed1979

[Influence of composition of the culture media on the in vitro determination of the bacterial sensitivity to sulfonamides, trimethoprim and cotrimoxazole].

The difficulties concerning the interpretation of results of susceptibility tests to sulphonamides, trimethoprim, co-trimoxazole have been investigated. The zones of inhibition produced by discs containing these drugs are peculiar since frequently they contain a light bacterial growth and small colonies. Therefore the real sensitivity or resistance of the microorganism is questionable. Susceptibility tests performed on media of different composition, have shown that the phenomenon is chiefly due to the presence in the medium of thymidine and methionine. Both the substances are end-products of the metabolic pathway on which act sulphonamides, trimethoprim, co-trimoxazole. When they are in the medium, they can be available for the bacteria in spite of the inhibition caused by the mentioned drugs.

Bacteria↗
PubMed1979

Na+/K+-dependent adenosinetriphosphatase activity in mammalian kidney.

Microsomal preparations with Na+/K+-dependent ATPase activity from the outer medulla of rabbit and pig kidney were obtained. Purifications were assaied by centrifugation on sucrose discontinuous gradients and gel-filtration on Sepharose 6B, after detergent incubation. Sodium dodecylsulfate, with ATP as protecting agent, can remove a maximal amount of non specific proteins from the membranes and allows the recovery of a fraction with very high specific activity. The approach to purification by affinity chromatography techniques leads to interesting results, which induce us to pursue the present researchs to applicate an affinity method to Na+/K+-ATPase.

Animals↗