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M Casu

Publications and source records attributed to M Casu.

At least 19 recordsLinked to original sources
PubMed1992

Analysis of sodium-23 nuclear magnetic resonance spin-lattice relaxation for the study of the intracellular sodium state.

Sodium-23 Nuclear Magnetic Resonance relaxation spectroscopy has been used to investigate the state of intracellular Na+ in control and CCl4-treated rat livers. The analysis of spin-lattice relaxation rates at 1.88 and 7.07 Tesla based on a two-site exchange model led to estimates of pertinent modulation times. Also it has been found that a relatively high quantity of Na+ (PB = 1.59 x 10(-2)) is bound to charged sites of intracellular macromolecules or membranes. The degree of binding strongly decreases in CCl4 treated rat livers.

Animals↗
PubMed1992

[Spectrum analysis of the r-r interval using a PC].

Spectral analysis of r-r variability has been recently proposed as a clinical tool to assess the autonomic nervous system function. In this article we present the results obtained using an equipment and an analysis software (based on Maximum Entropy Method) developed in our laboratory. Analyzing the tachograms derived from prolonged ECG registrations of 12 young healthy subjects, 24 to 36 years old (mean 31 +/- 4), we observed the two classic components of the signal: a low frequency component (0.7 +/- 0.2 Hz) and a high frequency component (0.21 +/- 16.6 Hz). As expected, standing, a simple manoeuvre augmenting sympathetic activity, caused a stronger predominance of the low frequency component. We conclude that our method is reliable to evaluate, by means of spectral analysis, rhythmical oscillations of r-r variability.

Adult↗
PubMed1991

A new glucose clamp algorithm: clinical validation.

A new glucose clamp technique for in vivo studies of insulin sensitivity was validated clinically. Eighteen patients (10 males, 8 females, age 35-80 years, body mass index 34.6-17.04) were connected to a computer-assisted artificial pancreas "Betalike R", using a new algorithm based on a "minimal model", to carry out the glucose clamp technique automatically and especially to overcome the well-known problems of its priming phase. We performed the euglycemic hyperinsulinemic clamp in four patients and the hyperglycemic hyperinsulinemic clamp in 14. In one patient both clamps were done. The mean priming time to reach steady-state glycemia was 20 min. Plasma insulin concentrations were measured every 20 min. This new automatic glucose clamp technique enables the priming phase to be run without any significant overshoot, and accidental variations of glycemia in steady state were reduced to a minimum. The system showed satisfactory safety and stability in controlling the patient's glycemia and assured high speed of the priming phase.

Adult↗
PubMed1991

[Evaluation of the characteristics and performance of an automatic sphygmomanometer (Omega 1400)].

24 hour pressure monitoring is a newly developing technique potentially yielding important informations in hypertensive patients. Numerous automated devices are available whose performance characteristics are poorly documented. To evaluate an automated sphygmomanometer commonly used in our Division (Omega 1400, Invivo Research Laboratories), we performed a series of measurements, simultaneously recording blood pressure in the opposite arm with a common sphygmomanometer. Each measure was then repeated reversing the position of the two devices (manual and automated), thus abolishing possible differences between the two arms. We observed a mean underestimation of 1.90 mmHg of systolic pressure and of 4.82 mmHg of diastolic blood pressure by the automated device. We conclude that the device by us evaluated is not advisable in the basal blood pressure evaluation, but useful in monitoring inpatients.

Automation↗
PubMed1991

[Blood pressure monitoring during hospital convalescence].

Blood pressure ambulatory monitoring has provided numerous and interesting informations on the clinical as well as investigational setting of arterial hypertension. The vast majority of data have been obtained registering blood pressure during the normal daily activities of the patients and surprisingly few studies have been undertaken to evaluate blood pressure behaviour in inpatients. We observed the 24 hours pattern of blood pressure in hypertensive and normotensive inpatients, using an automated sphygmomanometer (Omega 1400), whose performance was previously evaluated by us. The results demonstrate that blood pressure monitoring in inpatients could be a useful tool in managing hypertensive patients.

Adult↗
PubMed1990

[Complications and limitations of endoscopic therapy for urethral stenosis].

Endoscopic treatment of urethral stenosis is not an alternative to surgical therapy but is an ideal therapeutical partner. The limits of endoscopic resection lie in the lack of anatomopathologican and clinical knowledge regarding the long-term maintenance of stability of the urethral lumen that in every case the internal urethrotomy manages to create. In fact internal urethrotomy is capable of almost totally eliminating the urethral stenosis but with a higher incidence of relapse, even in the short-term. The complications of endoscopic therapy of urethral stenosis are the usual local complications and of mild seriousness. Among the most frequently noted are the swelling and/or peno-scrotal suffusion by incorrect routes, and post-operative urethraemorrhagia. More rarely, but with serious effects, are purulent urethritis or sepsis. In our case list major complications such as priapism, cavernositis or septic shock were not noted. In conclusion endoscopic therapy of urethral stenosis is a simple technique, repeatable with low morbidity and is the best technique in the congenital 'ring'.

Endoscopy↗
PubMed1989

An Na-23 and P-31 NMR investigation of sonicated cardiolipin sodium salt in aqueous medium.

Na-23 and P-31 nuclear magnetic resonance was used to investigate the structure and dynamics of Na+ trapped in the enclosed aqueous spaces of unilamellar vesicles of Cardiolipin sodium salt. After sonicated Cardiolipin sodium salt forms a clear solution in aqueous medium and gives rise to a narrow, isotropic P-31 NMR line. This line was attributed to the presence of either vesicles or more complex liquid crystalline structures showing superposed-signals for inner and outer phosphate groups. The use of paramagnetic shift reagent Dy(PPPi)2 made it possible to observe only the line of the phosphate groups arranged within the structures. From an analysis of the spin-lattice relaxation parameters of Na-23 at 21.04 MHz and 52.6 MHz, the correlation time tau = 1.3 x 10(-9) sec was estimated. It was then possible to calculate the value of 1.9 MHz for the quadrupolar coupling parameter. These findings were interpreted in terms of the occurrence of specific bindings between Na+ and the phosphate moieties within the unilamellar structures of Cardiolipin.

Cardiolipins↗
PubMed1987

NMR spin-lattice relaxation times of intracellular Na-23 on rat livers and related lipid peroxidation following CCl4 intoxication.

Liver tissues were isolated from rats acutely intoxicated with carbon tetrachloride, and Na-23 NMR signals were analyzed to investigate the T1 relaxation times of intracellular sodium ions under pathological conditions in presence of the paramagnetic shift reagent (dysprosium tripolyphosphate). We studied the significant increase of T1 found in CCl4 treated rats with respect to controls, which was elsewhere demonstrated as being independent of cell necrosis. Evidence is given that neither fat accumulation nor proliferative processes affect the observed T1 lengthening. When T1 relaxation times were measured in the liver of vitamin E treated rats subsequently intoxicated with carbon tetrachloride, a significative shortening of T1 with respect to CCl4-intoxicated rats was observed. These results were discussed in terms of the antioxidant action exerted by vitamin E, taking into account that peroxidation of microsomal lipids is the key factor in the process of carbon tetrachloride induced liver injury. Furthermore, the observed T1 changes were discussed in terms of the interactions of Na+ with cell membranes and/or the occurrence of viscosity changes.

Carbon Tetrachloride Poisoning↗
PubMed1986

Na-23 NMR spin-lattice relaxation times in rat tissues, and related modifications following CCl4 intoxication.

Intracellular Na-23 NMR signals were analyzed to investigate the T1 nuclear magnetic relaxation times of sodium ions in rat tissues under physiological conditions in presence of the shift reagent Dy(PPPi)2(7-). The T1 values so measured showed a high degree of reproducibility (10%). The order of T1 values found for the investigated rat tissues was the following: liver, spleen less than kidney less than muscle, brain less than blood. Furthermore, livers of rats treated with the known hepatotoxic agent CCl4 were studied. This tissue showed a significative increase of T1 with respect to those of normal rats. The T1 lengthenings were discussed in terms of various cellular injuries induced in the liver by CCl4 intoxication and our results showed that T1 lengthening did not depend on liver necrosis.

Animals↗
PubMed1979

Decrease of cyclic GMP in cerebellar cortex by intrastriatal (--)-sulpiride.

Intraperitoneal administration of (--)-sulpiride (12 to 50 mg/kg) produced a dose-related decrease in cGMP content in cerebellar cortex, while the (+)-sulpiride (10 microgram), but not after intracerebellar injection. These findings support the contention that (--)-sulpiride modifies cerebellar cGMP levels through and action on striatal dopamine receptors.

Animals↗
PubMed1978

Stimulation of dopamine synthesis in caudate nucleus by intrastriatal enkephalins and antagonism by naloxone.

The intraventricular injection of methionine-enkephalin (50 to 100 micrograms) or [d-Ala2]-methionine-enkephalinamide (1.5 to 12 micrograms), a synthetic enkephalin analog resistant to enzyme degradation, caused a marked dose-dependent increase in dihydroxyphenylacetic acid and homovanillic acid concentrations in the rat striatum. The [d-Ala2] analog increased the accumulation of dopa in the striatum after aromatic amino acid decarboxylase inhibition, indicating that it increased dopamine synthesis. At the highest doses used both enkephalins failed to modify brain serotonin metabolism. The monolateral microinjection of the [d-Ala2]] analog (3 to 6 micrograms) into the caudate nucleus increased the concentration of dihydroxyphenylacetic acid in the injected side, whereas bilateral injection increased the concentration of this compound in both caudate nuclei and caused catalepsy. The stimulant effect of the [d-Ala2] analog on dopamine synthesis in the striatum persisted after destruction of striatal postsynaptic dopamine receptors with kainic acid. The biochemical and behavioral effects of enkephalins were prevented by naloxone, a specific narcotic antagonist. The results indicate that enkephalins stimulate dopamine synthesis by an action on opioid receptors localized on dopaminergic nerve terminals.

3,4-Dihydroxyphenylacetic Acid↗