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Biomedical subjects

L Galzigna

Publications and source records attributed to L Galzigna.

At least 19 recordsLinked to original sources
PubMed1979

Liposome-incorporated enzymes: studies on amylase.

Alpha-amylase (EC 3.2.1.1) from hog pancreas was incorporated into artificial phosphatidylcholine and phosphatidylserine liposomes. To kinetically follow the enzyme-catalyzed hydrolysis of amylose the liposome-bound amylase was incubated in a medium containing amylose-iodine substrate. The reaction was studied at different concentrations of amylose and at different ionic strengths. Activation of amylase incorporated into liposomes by chloride ions varies with the type of phospholipid utilized to prepare the liposomes. Whe amylase bound to negative charged liposomes was used, a sigmoidal relationship between the reaction velocity and substrate concentration was found. Incorporation into liposomes protects amylase from heat inactivation.

Amylases↗
PubMed1979

Inhibition of rat liver mitochondrial 3-hydroxy-3-methylglutaryl-CoA lyase by succinyl-CoA.

1. Succinyl-CoA inhibits 3-hydroxy-3-methyl-glutaryl-CoA lyase (EC 4.1.3.4) when added to purified preparations of the enzyme. 2. The apparent Ki value is 2.1 x 10(-4) mol/l and the inhibition has the features of a partially competitive inhibition. 3. The effect of succinyl-CoA both added and enzymically produced on the lyase activity of sonically disrupted rat liver mitochondria results in decreased acetoacetate formation. 4. This occurs with mitochondria obtained from normal, starved and streptozotocin-diabetic rats.

Acyl Coenzyme A↗
PubMed1978

Electric hysteresis and mitochondrial incorporation of RNAs from different sources.

The paper reports the characteristics of four different RNAs from yeast, Torula and calf thymus of molecular weight ranging between 15,000 and 30,000. The gel-filtration behaviour with aqueous and partially qqueous solvents is studied together with the response of the four RNAs to static electric fields of strength ranging between 20 and 35 kV/cm. The relationship between molecular weight and extent of electric hysteresis is linear for all RNAs, while tRNA slightly deviates from such a relationship. The ability of the RNAs to permeate biological mebranes or bind membrane components such as lecithins is studied with rat liver mitochondria and a two-phase system with egg lecithin dissolved in the organic phase and RNA in the aqueous one. There is no apparent relationship between molecular weight of the RNAs and their ability to interact with biological membranes.

Animals↗
PubMed1978

Properties of two derivatives of gamma-aminobutyric acid (GABA) capable of abolishing Cardiazol- and bicuculline-induced convulsions in the rat.

The gamma-NH2 function of GABA was blocked with either benzoyl group (BG1) or a pivaloyl (timethylacetyl) group (PG2). The two derivatives of GABA obtained by the synthetic procedure were chemically pure and fully characterized. Both 14C-BG1 and 14C-PG2, unlike 14-C-GABA, are able to penetrate the blood-brain barrier in rats after subcutaneous injection. BG1 reached its highest concentration in brain 5 min after injection and PG2 after 30 min. This difference appears to be related to the different hydrophobic character of the two compounds, measured after experiments of partition in a water ethylacetate system, and to the different rate of diffusion following subcutaneous administration. BG1 abolished pentetrazole- and bicuculine-induced convulsions in rat when injected 5 min before the administration of the convulsants and PG2 had similar effects when injected 30 min before convulsants. BG1 and PG2 had a slight inhibitory effect on GAD and both BG1 and PG2 acted as substrates for the action of proteolytic enzymes that convert the two compounds back to GABA. Toxicity of both BG1 and PG2 was practically undetectable in rat following administration of the compounds up to 1 g/kg. Glutamate oxidation by rat brain mitochondria was not affected by either BG1 or PG2.

Animals↗
PubMed1977

Clinical importance of lipase determination by the turbidimetric procedure as compared with determination by a chromatrographic procedure.

The turbidimetric determination of serum lipase activity was compared with the chromatographic determination in three groups of patients, including patients affected by hepatic diseases, patients affected by pancreatic diseases and a control group. The two methods were also compared in the determination of lipase activity of human leucocytes in vitro. The results show that there is a good statistical correlation of lipase turbidimetrically determined at pH 9.15 and amylase in serum of normal individuals and in serum of patients with pancreatic diseases. There is no correlation between amylase and chromatographically determined lipase. The other types of lipase activity determined, i.e. turbidimetrically assayed at pH 5.5 and chromatographically assayed both at pH 5.5 and at pH 9.15, might be related to a different non-pancreatic enzymatic activity which is likely to lack diagnostic value. This suggests that methods of lipase determination based, for instance, on fatty acid liberation are of limited value in clinical studies on lipase.

Adult↗
PubMed1977

Characteristics and behaviour of arylesterase in human serum and liver.

Human arylesterase is localized in liver microsomes where the presence of different electrophoretic bands corresponding to the serum bands can be recognized. Serum arylesterase is mainly a result of liver activity and its high level might be explained by a low rate of elimination in urine. The behaviour of arylesterase towards inhibitors shows certain similarities to that of some of the proteases, such as trypsin. The clinical value of serum arylesterase determination in assessing liver function is confirmed by its isoenzyme behaviour in cirrhosis and porto-caval shunt.

Adolescent↗
PubMed1977

Enzymatic assay of fructose-1,6-diphosphate for the measurement of its utilization by tissues.

The enzymatic analysis of fructose-1,6-diphosphate by a coupled assay utilizing triose-phosphate isomerase, glycerol-3-phosphate dehydrogenase and aldolase was carried out in rat serum and human plasma after fructose-1,6-diphosphate administration. The rate of disappearance of fructose-1,6-diphosphate was determined and compared to the activity of aspecific phosphatase. The uptake of fructose-1,6-diphosphate by rat liver and ileum was also determined with the same method.

Alkaline Phosphatase↗
PubMed1976

Dielectric increment of low molecular weight RNA in dioxane after application of static electric fields.

A soluble RNA with a molecular weight between 15 000 and 23 000 was extracted from calf thymus and chromatographically purified. The RNA was slightly soluble in doxane (approx. 2.5 mug/ml) and RNA-dioxane solutions were used to fill a cell (452.02 pF capacitance) to which static electric fields of variable strength were applied. The dielectric permittivity of the solutions was measured at a fixed time interval after the application of the electric field. The RNA solutions showed a dielectric increment proportional to the strength of the applied field and to the RNA concentration. The existence of a hystersis effect was proven and the effect of the electric field on the RNA molecule might be related to a dielectric saturation phenomenon parallel to long-term changes of the molecule.

Animals↗
PubMed1975

Changes relevant to catecholamine metabolism in liver and brain of ascorbic acid deficient guinea-pigs.

A chronic deficiency of ascorbic acid was induced in guinea pig. The level of catecholamines, copper and the activities of ceruplasmin, catecholamine oxidase, monoamineoxidase and acetylcholinesterase were checked in brain, liver and serum. Also the levels of ascorbic acid and glutathione were measured in the organs of ascorbic acid-deficient animals. The most important changes due to the ascorbic acid deficiency were observed in the brain were monoamineoxidase, catecholamineoxidase, acetylcholinesterase and the concentration of catecholamines were altered. The statement that brain is the organ most affected by the ascorbic acid deficiency is discussed.

Acetylcholinesterase↗