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Biomedical subjects

G Galli

Publications and source records attributed to G Galli.

At least 235 records · Page 13Linked to original sources
PubMed1984

High performance liquid chromatography preparation of the molecular species of GM1 and GD1a gangliosides with homogeneous long chain base composition.

A semi-preparative, analytical high performance liquid chromatographic (HPLC) procedure is described for the isolation of molecular species of GM1 and GD1a gangliosides containing a single long chain base, C18 or C20 sphingosine, C18 or C20 sphinganine, each in its natural erythro or unnatural threo form. The threo forms were obtained from 2,3-dichloro-5,6-dicyanobenzoquinone/NaBH4 -treated gangliosides. The ganglioside molecular species separated by HPLC were analyzed for carbohydrate, fatty acid, and long chain base composition. In particular, long chain bases were submitted to gas-liquid chromatographic-mass spectrometric analyses as their trimethylsilyl (TMS) or N-acetyl-TMS derivatives, and chain length, presence or absence of C4-C5 double bond, and C-3 steric configuration were ascertained. The final preparations of individual molecular species of GM1 and GD1a gangliosides were more than 99% homogeneous in their saccharide moiety, contained a single long chain base (homogeneity higher than 99%), and had a fatty acid composition primarily of stearic acid (92 to 97%). All the individual molecular species of GM1 and GD1a gangliosides were also prepared in radioactive form by selective tritiation at C-3 of the long chain base. Their specific radioactivity ranged from 1.3 to 1.45 Ci/mmol. The availability of these molecular species of gangliosides is expected to facilitate studies aimed at ascertaining the role played by the hydrophobic portion in the functional behavior of gangliosides.

Chromatography, High Pressure Liquid↗
PubMed1983

The effect of cholestyramine on liver HMG-CoA reductase and cholesterol 7 alpha-hydroxylase in various laboratory animals.

The activity of HMG-CoA reductase and cholesterol 7 alpha-hydroxylase was assayed in the liver of rats, rabbits, hamsters and guinea pigs at the minimum of the day cycle and after one night fasting. The amount of HMG-CoA reductase, as determined after its complete dephosphorylation in vitro was of the same order of magnitude in the tested species. The dephosphorylated active form of the enzyme was detectable only in the rat. Cholesterol 7 alpha-hydroxylase activity was also much higher in the rat. Cholestyramine treatment stimulated the activity of both enzymes. In particular, the ratio between active and inactive HMG-CoA reductase in rabbits, hamsters and guinea pigs became of the same order of magnitude of that found in rats.

Animals↗
PubMed1983

Influence of species and sex on cholesterol 7 alpha-hydroxylase activity in experimental animals.

Cholesterol 7 alpha-hydroxylase activity was evaluated measuring by selected ion monitoring the amount of 7 alpha-hydroxycholesterol formed from endogenous microsomal cholesterol and from exogenously added [4-14C]cholesterol in incubations of liver microsomes. The enzyme activity was determined in female rats, hamsters and guinea pigs and results were compared with those obtained in male rats. The results suggest that there is no difference between male and females as far as the activity of the enzyme from endogenous cholesterol is concerned at least in rat liver. Moreover, saturation of the enzyme by the endogenous substrate was observed in all female animals in contrast to the male rat for which the enzyme was found to be not saturated, as already reported by others. From molar radioactivity of 7 alpha-hydroxycholesterol obtained during incubations with [4-14C]cholesterol, differences were also evidenced in the equilibration of the substrate with the endogenous pool of cholesterol. In the male rat, equilibration depended upon the concentration of radioactive cholesterol added to the medium and reached completion at 60 microM concentration. In female animals, molar radioactivity of 7 alpha-hydroxycholesterol was always linearly correlated with that of cholesterol in the medium but it was always lower than that one. This indicates that in the tested female animals only part of exogenously added cholesterol is accessible to the substrate pool of the enzyme.

Animals↗
PubMed1983

A simple model for studies on the regulation of cholesterol synthesis using freshly isolated hepatocytes.

Rat hepatocytes isolated by the procedure described here showed 3-hydroxy-3-methylglutaryl-CoA reductase activity in the range of that reported for rat liver at the maximum of the circadian cycle, even if they were taken from rats at the time of the minimum. The enzyme was present in cells as both its active dephosphorylated (20 +/- 8%) and the inactive phosphorylated forms. The enzyme activity and the ratio between the two forms were unaltered during 3 h of cell incubation. 25-Hydroxycholesterol (50 microM) induced about 50% inhibition of 3-hydroxy-3-methylglutaryl-CoA reductase activity during 1 h incubation but the relative amount of the two forms was not modified by the sterol. Cells isolated by the described procedure may therefore be a useful tool in studies on the regulation of cholesterol neogenesis, both through the synthesis of the enzyme, which can be shown by measuring the activity after complete dephosphorylation of the enzyme, and via the rapid reversible shift of the inactive to the active form, resulting from the ratio between the two enzyme forms. The latter mechanism for the modulation of cholesterol synthesis cannot be tested in cell cultures because full activation of the enzyme occurs during hepatocyte plating.

Animals↗
PubMed1983

Preferential utilization of endogenous arachidonate by cyclo-oxygenase in incubations of human platelets.

Thromboxane B2 (TXB2) and 12-hydroxy-5,8,10,14-eicosatetraenoic acid (12-HETE) formed from the endogenous and exogenous arachidonate during human platelet incubation, was evaluated by selected ion monitoring (SIM). TXB2 formed from endogenous substrate accounted for about one third of the total, whereas the great part of 12-HETE derived from exogenous arachidonate. These data indicate that under the tested conditions the pool of arachidonate that acts as substrate for cyclo-oxygenase is different from the pool that acts as substrate for lipoxygenase and that the arachidonate released from phospholipids is preferentially utilized by cyclo-oxygenase.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1983

A practical approach to the hepatobiliary kinetics of 99mTc-HIDA. Clinical validation of the method and a preliminary report on its use for parametric imaging.

99mTc-diethyl-HIDA cholescintigraphy was performed on 24 patients with histologically proven liver disease and on 10 normal adult subjects. Liver mass transport of HIDA was interpreted with the aid of a probabilistic model, assuming that the tracer particles undergo mixed random walks with drifts. The radiohepatograms were thus fitted with a gamma-variate function and the fitting parameters were evaluated as estimates of the severity of the disease. These parameters, together with the transit times, were also used to generate parametric images of liver function. The advantages of this approach are discussed and the following conclusions are drawn: (1) The gamma-fit is highly satisfactory with any type of experimental curve (0.98 less than r less than 1). (2) The parameters derived from the gamma-fit make it possible to objectively assess the extent of liver functional impairment. (3) Parametric imaging of the liver mass transport of HIDA is easily implemented, but still more experience is needed to assess its impact on patient care.

Bile Ducts↗
PubMed1983

99mTc-diethyl-IDA: the extraction efficiency of the liver.

The extraction efficiencies of the liver were studied in rabbits by injection in the portal vein of 99mTc-IDA and 131I-Rose Bengal in two experimental conditions. In the first experiment blood samples were collected for one minute from a catheter inserted into the vena cava with the tip at the sovrahepatic veins outflow level. The vena cava was ligated upperstream. In the second experiment blood was collected from the general circulation every other minute for 20' after administration. Control experiments were performed in rabbits by administration of 99mTc-Pertechnetate and 99mTc-Albumin. The results showed that the extraction of diethyl-IDA from the blood flowing through the liver is almost total.

Animals↗
PubMed1983

Microsurgical anterior cervical disk removal without interbody infusion.

A series of 57 patients with root syndromes or compressive myelopathy were operated upon by a modified Cloward technique. No bone grafts were used. The patients were observed for 6 months to 5 years after surgery. Of the 47 patients with radiculopathy, 44 were cured and three complained of minor pains in their arms. Of the 10 patients with myelopathy, three were greatly improved, five were slightly improved, and two remained unchanged. In 100% of these cases, immobilization of the involved interspace occurred within a year. The surgical technique is discussed.

Humans↗
PubMed1983

Biochemical complementation with RNA in the Xenopus oocyte: a small RNA is required for the generation of 3' histone mRNA termini.

When the cloned h22 histone gene repeat unit of the sea urchin Psammechinus miliaris is injected into the frog oocyte nucleus, transcription initiates faithfully in the promoter region of the H3 gene, but transcription termination or RNA processing to yield genuine H3 mRNA 3' ends is very inefficient. The generation of 3' ends can be enhanced by the injection of a small sea urchin poly (A)- RNA into the oocyte cytoplasm one day prior to injection of the histone gene repeat unit. This RNA is approximately 60 nucleotides in length and appears to be present in relatively low abundance in embryos of both Psammechinus and Paracentrotus. RNA extracted from a nuclear DEAE fraction, previously shown to complement the lesion in H3 gene expression, also causes the appearance of true 3' ends of H3 mRNA. Furthermore, RNA extracted from our 12S "termination" factor includes an RNA species comigrating with the 60 nucleotide RNA from poly (A)- RNA. We suggest that the 12S nuclear "termination" component is in fact a small nuclear RNP.

Animals↗
PubMed1983

Portal decompression through direct side-to-side mesocaval anastomosis in the management of certain forms of portal hypertension.

When performing a portosystemic shunt in patients with portal hypertension due to pre-hepatic block, a number of technical problems may arise. In these cases direct side-to-side mesocaval anastomosis through an interruption of the duodenum is favoured by the Authors. Two personal cases of young patients successfully treated by this procedure are reported. In both cases a central splenorenal shunt had been previously performed to treat a pre-hepatic block. The patients presented with recurrent gastrointestinal bleeding, which resulted from delayed thrombosis.

Child↗
PubMed1983

[Antithrombin III and fibrinogen after surgical interventions on the abdomen and heart].

We have explored the changes of plasma concentrations of antithrombin III and fibrinogen in patients recovering from major abdominal and cardiac surgery. In one group of patients subjected to major abdominal surgery we detected a statistically significant reduction of antithrombin III in the second and third postoperative day, followed by return to normal values in the fourth or fifth day. Fibrinogen, instead, increased to as much as 180% of the preoperative value in the first four postoperative days and reverted slowly to preoperative values between the fourth and the eighth day. In another group of patients subjected to cardiac surgery procedures utilizing the heart-lung machine, however, we found no significant reductions of antithrombin III in the early postoperative period. These results suggest the possible influence of local tissue factors affecting the plasma levels of antithrombin III differently in the two types of surgery under discussion. The patients subjected to extracorporeal circulation, on the other hand, showed a depletion of plasma fibrinogen down to less than 30 or 40% of preoperative values. This may reflect activation of coagulation processes and the considerable sequestration of fibrin at some interfaces of the heart-lung machine.

Abdomen↗
PubMed1983

[Kinetic studies of a new method for determining plasma fibrinogen].

Turbidimetric specific techniques (turbidity end-pot measurement after thrombin addition to the plasma) are widely used for fibrinogen determination. This paper describes a series of tests performed with the aim of establishing a fixed-time kinetic method based on the above mentioned technique. It is know that 1st order or pseudo 1st order reaction are the most valuable for the kinetic determination of substrates. However for this procedures, in contrast to end-point techniques, enzymes with the highest possible Michaelis constant are required. If the Michaelis constant values for the pair fibrinogen/thrombin determined in artificial systems have a molarity in the order of 10(-5)/l when the measurement is made on plasma, antithrombins which are powerful thrombin inhibitors, increase the Michaelis constant to a molarity of 10(-2)/l. For the thrombin in the reaction mixture we have adopted an activity of 1.6 National Institute of Health (NIH) units/100 microliter of plasma; this activity is sufficiently high to induce instantaneous start of fibrinogen polymerization, without affecting the 1st order kinetic. The preliminary studies which have been carried out to evaluate this technique have shown the following characteristics: a) it is both accurate and precise; b) it requires simple and fast operations; c) it may easily be automated with a productivity of about 200 tests/hour on micro centrifugal analyzer.

Blood Coagulation↗
PubMed1983

Impaired clearance of cholephilic anions in Rotor syndrome.

The behaviour of some cholephilic anions has been studied in three male patients (two of whom are brothers) affected with Rotor syndrome. The unconjugated bilirubin clearance was markedly reduced with impairment of the plasma-liver transfer constant rate (uptake defect). BSP retention at 45 min. was elevated without late rise of the anion. Transport maximum ("Tm") of BSP was slightly reduced; relative hepatic storage capacity of BSP ("S") was significantly impaired. Plasmatic retention of 131-I-Rose Bengal was increased with a diminished hepatic uptake of the compound. The hepatic excretion of IDA-derivatives was impaired, but less for parabutyl-IDA than for diethyl-IDA. It is concluded that in Rotor syndrome there exists an alteration of uptake and storage of several cholephilic organic anions: the alteration is common not only to substances that undergo intracellular conjugation--such as bilirubin and BSP--but also to substances that are not metabolized--such as Rose Bengal and IDA--derivatives. Finally the authors suggest that the Rotor syndrome and so--called "Hepatic storage disease" are the same condition.

Adult↗