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Biomedical subjects

C Motta

Publications and source records attributed to C Motta.

At least 19 recordsLinked to original sources
PubMed1990

Fluidity changes and chemical composition of lipoproteins in type IIa hyperlipoproteinemia.

The chemical composition and the physical properties of lipoproteins (VLDL, LDL and HDL) were studied in two groups of patients: 14 healthy normolipidemic subjects and 15 type IIa familial hypercholesterolemic patients. The steady-state fluorescence anisotropy rs was estimated in lipoproteins by the fluorescence depolarization of two fluorescent probes: the DPH (1,6-diphenyl-1,3,5-hexatriene) and the TMA-DPH (1,4-trimethylammonium phenyl-6-1,3,5-hexatriene). A structured order parameter S was calculated from the DPH fluorescence anisotropy. The flow activation energies were calculated for LDL and HDL from both groups from the Arrhenius plots (log r DPH versus 1/T). By using TNBS (trinitrobenzene sulfonic acid) as a distance control quencher, the two probes were located in the outer shell of LDL. In HDL, TMA-DPH remained at the surface of the particles, while DPH was more deeply embedded in the lipid core. There was no difference in the physico-chemical properties of VLDL between the two groups studied. DPH fluorescence anisotropies were significantly increased in LDL and HDL from the hypercholesterolemic group compared to the control particles (P less than 0.05 and P less than 0.01, respectively). In LDL this modification of the fluorescence anisotropy can be related to a change in the lipid composition of particles. LDL from hypercholesterolemic patients contained significantly less triacylglycerol (P less than 0.01) and more cholesteryl ester (N.S.). Their cholesteryl ester to triacylglycerol ratio was significantly higher. In HDL, there was no difference in chemical composition between the two groups. The increase in DPH fluorescence anisotropy can be related to the presence of smaller particles in HDL from HC group. No difference was noted in the TMA-DPH fluorescence anisotropy at 37 degrees C in the LDL from the two groups. In contrast, TMA-DPH fluorescence anisotropy in HDL from hypercholesterolemic group was significantly higher than in control HDL. The flow activation energy of DPH was also significantly higher in both LDL and HDL from the hypercholesterolemic group than in control group particles. In both LDL and HDL from the control group, DPH fluorescence anisotropy was negatively correlated with TG/protein and TG/PL ratios and positively correlated with the CE/TG ratio. No correlation was observed between lipid composition and DPH fluorescence anisotropy values in hypercholesterolemic particles. The modification in fluidity parameters, especially the increase in the flow activation energies in LDL and HDL from hypercholesterolemic patients, could lead to a restriction of cholesterol movements in these particles. From a physiological point of view, this could represent a loss of functional capacity.

Adult↗
PubMed1990

Effects of dietary fats on the fluidity of human high-density lipoprotein: influence of the overall composition and phospholipid fatty acids.

The present study was undertaken to analyze whether the changes induced by dietary manipulations in the chemical composition of HDL, particularly in total phospholipids, phosphatidylcholine and sphingomyelin fatty acid composition, modified their fluidity. 12 healthy women, aged 26-49 years were studied. They consumed, over periods of 5 weeks, various isocaloric diets, each containing 30% of the calories as fat. 15.6% of the total calories were provided successively by olive oil, soybean oil, corn oil, and milk fats. The HDL fluorescence anisotropy was measured with 1,6-diphenyl-1,3,5-hexatriene (DPH) by fluorescence polarization. The HDL from the monounsaturated diet, olive oil, were the most fluid particles. The HDL fluorescence anisotropy was positively correlated with their free cholesterol percentage and negatively correlated with their triacylglycerol content and their triacylglycerol/phospholipid ratio. Moreover, the HDL fluorescence anisotropy was negatively correlated with the percentage of oleic acid in their total phospholipids and particularly in the phosphatidylcholine. These results suggest that the percentages of triacylglycerol and oleic acid in phospholipids of HDL have a fluidifying effect on these lipoproteins.

Adult↗
PubMed1990

A compensatory mechanism improving red cell membrane fluidity in hemodialysed patients.

A fluorescence polarization technique with 1,6-diphenyl 1,3,5-hexatriene as a fluorescent probe was used to determine the fluidity of red cell membranes from hemodialysed patients before and after dialysis. After dialysis, there was a decrease in fluidity and activation energy values revealed a significantly changed distribution. The membrane lipid composition showed a significant increase in cholesterol after dialysis (p less than 0.001) and a significant reduction in saturated fatty acids (p less than 0.01) with an increase in unsaturated fatty acids (p less than 0.05). A compensatory mechanism could be suggested involving a reduction of saturated fatty acids in response to the increase in the cholesterol/phospholipid ratio. This could lead to an optimization of membrane fluidity.

Adult↗
PubMed1990

[CT study of fractures and pseudarthroses of the carpal scaphoid].

The authors analyze a group of 6 patients suffering from fractures and pseudoarthrosis of the carpal scaphoid; some of them were treated with Herbert bone screw. The authors emphasize the utility of CT, as proposed by Sanders (1988), in both pre- and postoperative evaluation of such conditions, since conventional X-rays can provide questionable findings as to both the state of the bone in the proximal fragment and the healing process at the fracture line.

Adult↗
PubMed1990

[Delayed consolidation and pseudarthrosis in posttraumatic pathology of the carpal scaphoid. A magnetic resonance study].

Delayed unions and fibrous or sclerotic non-unions of the carpal scaphoid are frequent sequelae of non-diagnosed or not properly treated fractures. The most important cause of abnormal unions is ischemic necrosis, due to the terminal vascularity of the carpal scaphoid. Conventional X-rays, scintigraphy, and CT do not yield sufficient information for a complete diagnosis; at present, MR imaging represents a valuable alternative, for it is a noninvasive technique able to provide a "biological imaging" of bone. Fourteen patients underwent surgical/nonsurgical treatment, based on the findings supplied by MR imaging. MR reliability was evaluated in relation to the therapeutic results obtained. The study proved MR imaging to provide important information as to therapy planning; in case of surgical treatment, MR imaging helped in choosing the most appropriate location for the insertion of bone graft or screw.

Adolescent↗
PubMed1989

Mechanism of increased erythrocyte membrane fluidity during magnesium deficiency in weanling rats.

The erythrocyte membrane was investigated in weanling male rats pair fed with magnesium-deficient and control diets for 8 days. Fluorescence polarization studies revealed a 15% increase in the fluidity of membranes from deficient rats. A similar increase in the fluidity of liposomes indicated that protein was not involved. The change was associated with decreased osmotic fragility of intact erythrocytes; the cells lost their biconcavity and had a flattened appearance with surface irregularities. Analysis of the membranes showed decreased amounts of magnesium, cholesterol, and sphingomyelin in the deficient group. The reduced ratios of cholesterol to phospholipid and sphingomyelin to phosphatidylcholine were consistent with the increased fluidity. Addition of physiological amounts of magnesium to the medium rigidified membranes incubated in tris(hydroxymethyl)-aminomethane buffer, and this was prevented by the presence of EDTA. Cross-incubation experiments with erythrocyte ghosts and plasma from the two groups of rats showed that magnesium-deficient plasma increased the fluidity of control ghosts and control plasma rigidified ghosts from magnesium-deficient rats. Addition of sufficient magnesium chloride to raise the magnesium content of deficient plasma to normal had no significant effect. These results show that the increased fluidity of the erythrocyte membrane in magnesium deficiency is due to physicochemical exchange with the plasma. Although magnesium can directly influence membrane fluidity, the change during its deficiency in vivo is mainly mediated indirectly via disturbances in lipid metabolism.

Animals↗
PubMed1989

Effect of azelastine on microviscosity of bronchial lavage fluid obtained from actively sensitized and challenged guinea pigs.

Fluorescence polarisation technique was adapted to measure microviscosity in the bronchoalveolar lavage fluid (BAL) of guinea pigs. In sensitized guinea pigs, 20 hours after antigen challenge, the microviscosity of BAL was increased by 86%, suggesting that antigen-induced bronchospasm is followed by inflammatory events. Pretreatment with azelastine (3 mg/kg, p.o., 2 hours prior to antigen challenge) tended to normalize microviscosity in the bronchoalveolar lavage fluid obtained from challenged guinea pigs. The present results suggest that azelastine inhibits the increase of microviscosity of BAL, a symptom of the late phase reactions.

Animals↗
PubMed1988

[Fluorescence polarization studies of rat gastric surfactant: effects of aspirin].

Rat gastric surfactant has been studied by fluorescence polarization, both in a basal state and after an aspirin challenge. Gastric surfactant appeared as a very viscous molecular organisation of phospholipids and was disorganised by low, non ulcerogenic, concentrations of aspirin. The method presented herein allows one to study the human gastric surfactant under physiological and pathological condition and should help in the design of synthetic surfactants for a therapeutical purpose.

Animals↗
PubMed1988

[Changes of erythrocyte and lymphocyte membrane fluidity after plasma extraction in children with type II homozygous hypercholesterolemia].

Two young girls with type IIa homozygotic familial hypercholesterolemia were treated by plasma exchange to reduce circulating cholesterol levels, values prior to treatment being abnormally elevated (greater than 10 mmol/l). Simultaneous determination of membrane fluidity (by fluorescence polarization) of erythrocytes and lymphocytes showed marked decreases due principally to an increase in the intramembrane cholesterol/phospholipid ratio. Values after treatment showed a tendency to return to physiologic levels without, however, attaining normal values. In vitro studies of cholesterol incorporation in these membranes demonstrated the primordial role of cholesterol in these processes of membrane rigidity, and their reversibility. It is suggested that certain physical membranal properties could provide a useful index to assess need for more or less frequent plasma exchanges.

Child↗
PubMed1988

Membrane fluidity of Toxoplasma gondii: a fluorescence polarization study.

Toxoplasma gondii membrane fluidity was investigated by fluorescence polarization. We used 1,6-diphenyl 1,3,5-hexatriene (DPH) as a fluorescent hydrophobic probe. Fluorescence anisotropy (r) and degree of order (s) showed high fluidity properties. Chemical analysis was performed on this parasite. We found a low cholesterol/phospholipid ratio, many unsaturated fatty acids chains, and high phosphatidylcholine and low sphingomyelin amounts. These results were in good agreement with the observed high fluidity. This may be related to the great adaptability of Toxoplasma gondii in infesting a wide variety of host cells.

Animals↗
PubMed1985

Microviscosity of tracheal aspirates in newborns with respiratory distress.

The microviscosity of tracheal aspirates from newborn children with respiratory problems was investigated using fluorescence polarization. The pulmonary status of 100 newborns with hyaline membrane disease (HMD) and a reference group (n = 45) was assessed daily throughout of intubation. Two main changes in phospholipid microviscosity (eta) were identified. A decrease in eta associated with a favourable clinical outcome. A dramatic increase in eta with an unfavourable outcome in pulmonary function. These changes correlated with clinical observations, but the trends in microviscosity seemed to appear before any related clinical sign. It is proposed that the measurement of tracheal microviscosity provides a method for checking pulmonary function in the first days of life. The method is rapid and sensitive; it detects small variations barely detectable using more conventional ways by which pulmonary phospholipids are usually studied.

Fluorescence Polarization↗
PubMed1979

[Foetal pulmonary maturity: estimation by the palmitic/stearic acids ratio and by the Clements' test in amniotic fluid (author's transl)].

Two parameters have been used to estimate the foetal pulmonary maturity: Clements' test or bubble test and palmitic acid/stearic acid ration. The reliability and the limits of these tests have been studied in function of several pathological pregnancies and the gestations's age. A value greater than 5 for the P/S ratio was a good pronostic at any gestational age. A value lesser than 5 should be examined according to this gestational age. A negative Clements' test has to be confirmed by an another amniocentesis, while a positive test have been followed always by a mature newborn's birth.

Amniocentesis↗