Biomedical subjects
Publications and source records attributed to C Velussi.
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Platelet surface receptors for von Willebrand factor and for fibrinogen (glycoproteins GPIb and GPIIb/IIIa) were studied with monoclonal antibodies CD42 and CD41 and cytofluorometry in 31 healthy subjects, 10 hemodialysis patients with no A-V fistula obstruction (patent original fistula), 10 hemodialysis patients with frequent A-V fistula obstruction (more than twice), 12 patients with mild chronic renal failure (creatinine 1.75 +/- 0.40 mg/100 ml), 11 patients with advanced chronic renal failure (creatinine 5.62 +/- 1.22 mg/100 ml), and 10 patients with end-stage renal disease (ESRD) treated with peritoneal dialysis. There was a significant increase of platelet surface glycoproteins GPIb and GPIIb/IIIa in the population of hemodialysis patients with frequent A-V fistula obstruction. The expression of these platelet receptors might be related to the prothrombotic tendency of a group of patients with ESRD, who suffer more occlusive and thrombotic events of the A-V fistula. This group of patients may also have a higher frequency of systemic thrombotic and atherosclerotic complications.
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The myofibrillar changes of rat denervated soleus muscle were studied in the presence and in the absence of an antifibrillatory drug. After bilateral sciaticotomy, a concentrated solution of procainamide hydrochloride was steadily released, by way of a miniosmotic pump, in the space between the soleus and the gastrocnemius muscles of one leg. Fibrillation activity of soleus muscles was checked electromyografically at 3- to 5-day intervals. On the 21st day following denervation the muscles were excised, stained for adenosine triphosphatase activity and analysed for myosin heavy chain (MHC) isoforms. In the denervated-procainamide-treated muscles fibrillation was consistently (-75% on average) depressed in comparison to the contralateral denervated muscles. Type 1 (slow) fibres and MHC isoform were also significantly reduced, to the advantage of type 2A (fast) fibres and MHC isoform. The results support the view that denervation inactivity, like other kinds of muscle inactivity, favours the expression of fast type myofibrillar isoforms, and that this effect is counteracted, at least partially, by the spontaneous activity of the denervated muscle.
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Flunoxaprofen is a new nonsteroidal antiinflammatory agent that, like benoxaprofen, inhibits leukotriene rather than prostaglandin synthesis. The absorption and disposition kinetics of flunoxaprofen and benoxaprofen have been compared in six healthy volunteers after oral administration of 100 mg of each drug. The two drugs showed similar absorption characteristics, whereas the distribution and elimination processes were much faster for flunoxaprofen. The renal route of elimination appeared to contribute significantly less to the disposition of flunoxaprofen. These kinetic characteristics render less likely the risk of excessive drug accumulation with flunoxaprofen, especially in the presence of reduced renal function.
We have examined mathematically the "cause-effect" relationship between the phenomenon of emission of microvesicles and that of erythrocytic sphericitation, especially when the age of the cell is the main factor involved.
This methodological investigation is a formal and short outline of a rheological model for human plasma. Such a model proposal originates from equations and formulae for viscosity of colloidal suspensions and macromolecular solutions established by several authors (R. Simha, G. I. Taylor, W. and H. Kuhn). The model here proposed requires very hard oversimplifications and it may be considered as a semiempirical approach.
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Distributions of intervals between MEPP's, recorded from the frog sartorius muscle in various experimental conditions, were compared, graphically and by X2, with the exponential distributions expected for a Poisson process. For each experiment, 200 intervals were measured. In isotonic Ringer solutions containing no Ca++, MEPP's fitted an exponential distribution; by adding Ca++ (1 mM, 2,5 MM, 15 mM), the fit between empirical and expected distributions became poorer, with an excess of short intervals. MEPP's showed the tendency to occur in bursts, and this was particularly evident at 15 mM Ca++. In the presence of 0,5% ethanol, also at high Ca++ the intervals between MEPP's showed a fair fit to the exponential distribution. In Ringer solutions made hypertonic by the addition of 50 mM sucrose, the fit was poor and there was a relative lack of short intervals. These different patterns of MEPP distribution could be explained by supposing that Ca++, ethanol and hypertonicity activate different mechanisms of transmitter release.
Miniature end-plate potentials (MEPPs) were recorded intracellularly from sartorius muscle of Rana esculenta. Tracings were divided into time bins whose duration approximated one-fifth of the mean interval between consecutive potentials. The observed number of bins containing 0, 1, 2, ... MEPPs was compared, by the X2 test, with the number calculated from the Poisson equation. MEPP timing was analyzed in the absence as well in the presence of Ca2+ (1 mM, 2.5 MM, and 15 mM). In half of the experiments, 0.5% ethanol was added to the bathing solution. In the absence of Ca2+, MEPP timing fitted the Poisson predictions. On adding Ca2+, the fit became poor and MEPPs showed the tendency to cluster. At 15 mM Ca2+, no experiment proved to be Poissonian. Though increasing the frequency of MEPPs similarly to Ca2+, ethanol maintained a Poissonian release of transmitter at any concentration of Ca2+. It is suggested that ethanol masks the effects of Ca2+ on MEPP timing by also inducing the discharge of transmitter outside the Ca2+-dependent sites of exocytosis in the presynaptic membrane.
Section of the sciatic nerve, performed after a week of muscular disuse, is followed by fibrillation earlier in the soleus (S) than in the anterior tibialis (AT) muscle of the rat. The subsequent development of fibrillation, which is different in the control denervated S as compared with the control denervated AT, tends to become similar in the disused-denervated muscles.
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This work reports on a method of analysis and statistical correlation of electromyographic and cephalometric parameters. Has been employed a computer as oscilloscop with digital memory.