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Biomedical subjects

M Canepari

Publications and source records attributed to M Canepari.

At least 37 records · Page 2Linked to original sources
PubMed1998

Prostatic abscess: diagnosis and treatment.

OBJECTIVE: Prostatic abscesses are uncommon in clinical practice because early antibiotic therapy has reduced complications of prostatitis. Prostatic abscess mainly affects diabetic and immunosuppressed patients. The organisms most frequently involved are Escherichia coli and Staphylococcus, whereas gonococcus is rarely encountered. The results in eight men with prostatic abscess, five of whom were treated with sonographically guided percutaneous drainage, are reported. The diagnosis, clinically suspected in only three patients, was confirmed by transrectal sonography. All patients experienced complete abscess resolution. CONCLUSION: Transrectal sonography is the most reliable imaging method to diagnose prostatic abscess. Percutaneous transperineal or transrectal drainage is the first choice for therapy because of the lower risk of complication compared with surgery.

Abscess↗
PubMed1997

Chemo-mechanical energy transduction in relation to myosin isoform composition in skeletal muscle fibres of the rat.

1. ATP consumption and force development were determined in single skinned muscle fibres of the rat at 12 degrees C. Myofibrillar ATPase consumption was measured photometrically from NADH oxidation which was coupled to ATP hydrolysis. Myosin heavy chain (MHC) and light chain (MLC) isoforms were identified by gel electrophoresis. 2. Slow fibres (n = 14) containing MHCI and fast fibres (n = 18) containing MHCIIB were compared. Maximum shortening velocity was 1.02 +/- 0.63 and 3.05 +/- 0.23 lengths s-1, maximum power was 1.47 +/- 0.22 and 9.59 +/- 0.84 W l-1, and isometric ATPase activity was 0.034 +/- 0.003 and 0.25 +/- 0.01 mM s-1 in slow and in fast fibres, respectively. 3. In fast as well as in slow fibres ATP consumption during shortening increased above isometric ATP consumption. The increase was much greater in fast fibres than in slow fibres, but became similar when expressed relative to the isometric ATPase rate. 4. Efficiency was calculated from mechanical power and free energy change associated with ATP hydrolysis. Maximum efficiency was larger in slow than in fast fibres (0.38 +/- 0.04 versus 0.28 +/- 0.03) and was reached at a lower shortening velocity. 5. Within the group of fast fibres efficiency was lower in fibres which contained more MLC3f. We conclude that both MHC and essential MLC isoforms contribute to determine efficiency of chemo-mechanical transduction.

Adenosine Triphosphatases↗
PubMed1997

Experimental analysis of neuronal dynamics in cultured cortical networks and transitions between different patterns of activity.

Experimental investigation of the dynamics of biological networks is a fundamental step towards understanding how the nervous system works. Spontaneous activity in cultured networks of cortical neurons has been investigated by using a multisite recording technique with planar electrode arrays. In these networks, the spatiotemporal firing patterns were studied in the presence of different extracellular solutions. Transitions from asynchronous firing dynamics to synchronous firing dynamics were observed when the extracellular Ca2+ concentration was increased from 0.1 mM to 1 mM. Addition of extracellular Mg2+ reduced the spontaneous activity at any Ca2+ concentration, and an increase in the extracellular K+ concentration enhanced the frequency of periodical synchronous bursts. N-methyl-D-aspartate (NMDA) and non-NMDA glutamate receptor antagonists inhibited synchronous activity. A spatiotemporal analysis of the data has been performed, and the properties of the network such as the synchronization and the periodicity have been quantified in order to clarify how variations of intrinsic parameters of the network can induce structural transitions in the neural dynamics. This experimental study is a possible approach to investigate the computational properties of a neuronal network.

Animals↗
PubMed1997

Fibre types in skeletal muscles of chronic obstructive pulmonary disease patients related to respiratory function and exercise tolerance.

This study aimed to investigate the relationship between skeletal muscle, fibre type composition, functional respiratory impairment and exercise tolerance in patients with moderate to severe chronic obstructive pulmonary disease (COPD). A group of 22 COPD patients and 10 healthy control subjects were studied. In COPD patients, vital capacity (VC) and forced expiratory volume in one second (FEV1) were reduced to 79% and 51%, respectively. Diffusion indices (transfer factor of the lung for carbon monoxide (TL,CO) and carbon monoxide transfer coefficient (KCO)) were also reduced. Arterial oxygen tension (Pa,O2) was normal or slightly altered. A maximal exercise test was performed and anaerobic threshold was calculated. Muscle samples from vastus lateralis were obtained by needle biopsy. Myosin heavy chain (MHC) and light chain (MLC) isoforms were separated by gel electrophoresis and quantified by densitometry. MHC isoforms were considered as molecular markers of fibre types. The proportion of the fast MHC-2B isoform was increased in COPD patients. TL,CO, KCO, VC and FEV1 were positively correlated with slow MHC isoform content. TL,CO and KCO were also negatively correlated with the content of the fast MHC-2B isoform. No correlation was found between exercise parameters and MHC isoform composition. The co-ordinated expression between MHC and MLC isoforms was altered in COPD patients. We conclude that reduced oxygen availability, probably in combination with muscle disuse, may determine muscle alterations in chronic obstructive pulmonary disease patients. The altered correlations between myosin heavy chain and light chain isoforms suggest that co-ordinated protein expression is lost in chronic obstructive pulmonary disease muscles.

Adult↗
PubMed1997

Contractile properties and fiber type distribution of quadriceps muscles in adults with childhood-onset growth hormone deficiency.

Adults with GH deficiency (GHD) report weakness and fatigability. The origin of such symptoms is still debated. This work aimed to clarify whether weakness and fatigability depend on impairment of skeletal muscle contractile capacity. Five males with childhood-onset GHD (age +/- SE, 29.6 +/- 1.9) and 13 age- and sex-matched controls were enrolled in the study. Quadriceps muscle cross-sectional area (CSA), strength, twitch characteristics, and fatigue index of voluntary and electrically evoked contractions were determined in vivo in all subjects. Fiber type distribution and CSA of identified types of skeletal fibers were determined on needle biopsy samples of the vastus lateralis muscle of all subjects. Fiber type distribution was assessed on the basis of myosin heavy chain (MHC) isoform composition determined by electrophoresis on polyacrylamide gels. Fiber CSA was determined on cross-cryosections of fiber bundles immunostained by monoclonal antibodies against MHC isoforms. Absolute values of strength and fiber CSA of quadriceps were significantly lower in patients affected by GHD than in controls. However, once strength and fiber CSA were normalized for quadriceps CSA and subject height, respectively, differences disappeared. No difference was found between GHD patients and controls for quadriceps muscle twitch characteristics, fatigue index, and fiber type distribution. The results reported here suggest that weakness and fatigability in childhood-onset GHD do not have a skeletal muscle origin.

Adult↗
PubMed1996

Force-velocity properties of human skeletal muscle fibres: myosin heavy chain isoform and temperature dependence.

1. A large population (n = 151) of human skinned skeletal muscle fibres has been studied. Force-velocity curves of sixty-seven fibres were obtained by load-clamp manoeuvres at 12 degrees C. In each fibre maximum shortening velocity (Vmax), maximum power output (Wmax), optimal velocity (velocity at which Wmax is developed, Vopt), optimal force (force at which Wmax is developed, Popt), specific tension (Po/CSA, isometric tension/cross-sectional area) were assessed. Unloaded shortening velocity (Vo) was also determined at 12 degrees C in a different group (n = 57) of fibres by slack-test procedure. 2. All fibres used for mechanical experiments were characterized on the basis of the myosin heavy chain (MHC) isoform composition by sodium dodecyl sulphate (SDS)-polyacrylamide gel electrophoresis and divided into five types: type I (or slow), types IIA and IIB (or fast), and types I-IIA and IIA-IIB (or mixed types). 3. Vmax, Wmax, Vopt, Popt, Vopt/Vmax ratio, Po/CSA and Vo were found to depend on MHC isoform composition. All parameters were significantly lower in type I than in the fast (type IIA and IIB) fibres. Among fast fibres, Vmax, Wmax, Vopt and Vo were significantly lower in type IIA and than in IIB fibres, whereas Popt, Po/CSA and Vopt/Vmax were similar. 4. The temperature dependence of Vo and Po/CSA was assessed in a group of twenty-one fibres in the range 12-22 degrees C. In a set of six fibres temperature dependence of Vmax was also studied. The Q10 (5.88) and activation energy E (125 kJ mol-1) values for maximum shortening velocity calculated from Arrhenius plots pointed to a very high temperature sensitivity. Po/CSA was very temperature dependent in the 12-17 degrees C range, but less dependent between 17 and 22 degrees C.

Adult↗
PubMed1996

CCD imaging of the electrical activity in the leech nervous system.

A single ganglion of the nervous system of the leech Hirudo medicinalis was isolated. One or both roots emerging from each side of the ganglion were sucked into suction pipettes used either for extracellular stimulation or for recording the gross electrical activity. The ganglion was stained with the fluorescence voltage sensitive dye Di-4-Anepps. The fluorescence was measured with a nitrogen cooled CCD camera. Our recording system allowed us to measure in real time slow optical signals corresponding to changes in light intensity of at least 5/1000. These signals were caused by the direct polarization of neuronal structures, the afterhyperpolarization or the afterdischarge induced by a prolonged stimulation. When images were acquired at fixed times, several of them could be averaged and optical signals of at least 2/1000 could be reliably measured. These optical signals originated from well identified neurons, such as T, P and N sensory neurons. By taking images at different times and at different focal planes, electrical events could be followed at a temporal resolution of 50 Hz. The three dimensional dynamics of electrical events, initiated by a specific stimulation, was imaged and the spread of excitation among leech neurons was followed. When two roots were selectively stimulated, their neuronal interactions could be imaged and the linear and non-linear terms of the interaction could be characterized.

Animals↗
PubMed1996

Whole-muscle and single-fibre contractile properties and myosin heavy chain isoforms in humans.

The contractile characteristics of three human muscle groups (triceps surae, quadriceps femoris and triceps brachii) of seven young male subjects were examined. The contractile properties were determined from electrically evoked isometric responses and compared with fibre type composition determined from needle biopsy samples. Fibre types were identified using myosin heavy chain (MHC) isoforms as molecular markers with gel electrophoresis (SDS-PAGE) and histochemical ATPase staining. Four contractile parameters (twitch time to peak torque, the maximal rate of torque development, frequency response and fatiguability) were found to be related to fibre type composition. From the biopsy samples, single muscle fibres were isolated and chemically skinned. Isometric tension (Po) unloaded shortening velocity (Vo) and rate of tension rise (dP/dt) were determined. Each fibre was classified on the basis of its MHC isoform composition determined by SDS-PAGE. Fibres belonging to the same type showed identical contractile parameters regardless of the muscle of origin, except minor differences in Po of the fast fibres and dP/dt of slow fibres. The results are in favour of the conclusion that fibre type composition, determined using MHC isoforms as markers, is the major determinant of the diversity of contractile properties among human muscle groups.

Adult↗
PubMed1995

Direct depressant effect of phosphodiesterase inhibitors on ATPase activity of rat cardiac myofibrils.

The aim of this study was to determine (i) whether phosphodiesterase inhibitors influenced ATPase activity of maximally calcium activated cardiac myofibrils and (ii) whether this effect varied in relation to isomyosin composition. Myofibrils were prepared from ventricular myocardium of 2- to 3-month-old rats. ATPase activity was determined at low ionic strength at high (> 7.5) and low (4.4) pCa. Five compounds (amrinone, milrinone, enoximone, piroximone, and rolipram) were examined at concentrations between 10 microM and 1 mM. The results obtained showed that only milrinone and amrinone inhibited ATPase activity; inhibition was dose dependent, and milrinone was more potent than amrinone. To assess whether isomyosin composition might influence the responsiveness of myofibrils to phosphodiesterase inhibitors, the effect of 1 mM milrinone was also determined in myofibrils from hypothyroid rats. According to previous observations hypothyroidism caused an isomyosin shift from V1 to V3 in rat ventricular myocardium. The inhibitory effect of milrinone was lower in myofibrils prepared from hypothyroid rats than in myofibrils from euthyroid rats.

Adenosine Triphosphatases↗
PubMed1995

Maximum speed of shortening and ATPase activity in atrial and ventricular myocardia of hyperthyroid rats.

The kinetic properties of the myofibrillar system of atrial and ventricular myocardia of hyperthyroid rats were analyzed by determining ATPase activity and maximum shortening velocity. Hyperthyroidism was induced by daily subcutaneous injections of triiodothyronine (0.2 mg/kg body wt) for 2 wk. The treatment induced a marked atrial and ventricular hypertrophy and, in ventricular myocardium, an isomyosin shift toward a homogeneous V1 composition. Skinned trabeculae and purified myofibrils were prepared from atrial and ventricular myocardia. Enzymatic assays on the myofibrils showed that both Ca-stimulated ATPase activity and Ca-Mg-dependent ATPase activity had equal values in atrial and ventricular myocardia. In skinned trabeculae during maximal Ca activations, force-velocity curves were determined by load-clamp maneuvers, and unloaded shortening velocity (Vo) was obtained with the slack-test method. Both maximum shortening velocities extrapolated from the force-velocity curves (Vmax) and Vo were significantly higher (+68 and +52%, respectively) in atrial than in ventricular preparations. Developed tension was significantly greater in ventricular preparations. Maximum power output was not significantly different. Previous findings (V. Cappelli, R. Bottinelli, C. Poggesi, R. Moggio, and C. Reggiani. Circ. Res. 65: 446-457, 1989) had led to the conclusion that variations in ATPase activity and shortening velocity of ventricular myocardium can be accounted for by changes in isomyosin composition. In this light, the present results suggest that 1) ATPase activity is equal in atrial and ventricular myocardia as the two tissues contain the same myosin heavy chain isoform, 2) the difference in maximum speed of shortening between atrium and ventricle might be due to the presence of tissue-specific isoforms of myosin light chains.

Adenosine Triphosphatases↗
PubMed1994

Myofibrillar ATPase activity during isometric contraction and isomyosin composition in rat single skinned muscle fibres.

1. Myofibrillar ATPase activity, isometric tension (Po) and unloaded shortening velocity (Vo) were determined in single skinned fibres isolated from rat hindlimb muscles during maximal calcium activation at 12 degrees C. In each fibre, myosin heavy chain (MHC) isoforms were identified using electrophoresis and immunocytochemistry. ATPase activity was determined spectrophotometrically from NADH oxidation in a coupled enzyme assay. 2. On the basis of their MHC isoform composition, the fibres (n = 102) were divided into five groups containing the slow isoform, I MHC, or one of the fast isoforms, IIB MHC, IIA MHC, IIX MHC, or a mixture of the latter three. ATPase activity was significantly higher in IIB than in 2X and IIA fibres (0.230 +/- 0.010, 0.178 +/- 0.023 and 0.168 +/- 0.026 nmol mm-3 s-1, respectively). Mixed fibres had intermediate values. ATPase activity in slow fibres was considerably less (0.045 +/- 0.006 nmol mm-3 s-1). 3. The ratio between ATPase activity and Po, i.e. tension cost, was found to be 2.90 +/- 0.09, 2.56 +/- 0.14, 1.89 +/- 0.22, 1.52 +/- 0.13 and 0.66 +/- 0.004 pmol ATP nM-1 mm-1 s-1 in IIB, mixed, IIX, IIA and slow fibres, respectively. All the differences were statistically significant except that between IIA and IIX fibres. 4. Within each group of fibres with the same MHC composition, ATPase activity was found to correlate with Po, but not Vo. However, ATPase activity was found to correlate with Vo when all the fibre types were pooled together. 5. In thirty-seven fast fibres the MLC ratio, i.e. the proportion of the fast alkali light chain isoform, MLC3f, to the amount of the regulatory light chain, MLC2f, was determined. IIB fibres had the highest proportion of MLC3f and IIA fibres, the lowest. 6. A multiple regression analysis, used to distinguish between the effects of MHC and MLC composition, showed that ATPase activity was insensitive to the MLC ratio, whereas it had a significant impact on Vo. 7. The results obtained in this study indicate that in rat skeletal muscle fibres: (a) ATPase activity during isometric contractions and tension cost are strongly dependent on MHC isoform composition, and (b) there is no evidence that the alkali MLC ratio is a determinant of ATPase activity.

Adenosine Triphosphate↗
PubMed1994

Effects of acidosis on maximum shortening velocity and force-velocity relation of skinned rat cardiac muscle.

This study was designed to assess whether maximum shortening velocity and force-velocity parameters were reduced by acidosis in rat skinned cardiac trabeculae, as reported for skinned skeletal muscle. Thin trabeculae were dissected from right ventricle of adult male Wistar rats, chemically skinned, and maximally Ca-activated at pH 7.0, 6.6 and 6.2. Maximum tension (Po), maximum shortening velocity evaluated from force-velocity curves (Vmax), and maximum power output (Wmax) were significantly reduced for exposure to pH 6.6 and 6.2. When the value at pH 7.0 is taken as reference, Po decreased by 30% and 49%, Vmax by 17% and 40% and Wmax by 30% and 60% at pH 6.6 and 6.2 respectively. A similar reduction (25% at pH 6.6 and 42% and pH 6.2) was observed when unloaded shortening velocity (Vo) was determined with the slack test method. The results obtained show that both Po and Vmax or Vo are affected by a substantial decrease in pH. The combination between significantly lower Po and Vmax gives rise to significantly lower Wmax. The reduction of maximum shortening velocity (Vmax or Vo) can be explained by assuming either the existence of an internal load or an impairment in actin-myosin interaction.

Acidosis↗
PubMed1994

New uses of mammary ultrasonography.

This article reports the experience acquired through the use of ultrasonography applied to the study of the mammary gland affected by augmentation or reduction mammaplasty. Thirty-eight patients who had undergone either augmentation or reduction mammaplasty were submitted to ultrasonographic examination. Such a technique, besides being easy to perform, noninvasive, specific, and well accepted by the patients, showed to be remarkably interesting. It offered a wide display of the mammary parenchyma, showing its possible alterations, and supplying useful information on any possible postoperative implant ruptures, cicatricial reactions, seromas, and any other possible alterations that occurred.

Adult↗
PubMed1994

Propionyl-L-carnitine prevents myocardial mechanical alterations due to pressure overload in rats.

This study investigated if propionyl-L-carnitine (PLC) treatment can directly affect cardiac mechanics, secondary to increase in myocardial carnitine content, in rats with aortic constriction and sham-operated controls. After weaning, rats were fed one of the following diets for 8 wk: 1) a low-carnitine diet (containing 2 nmol/g carnitine); 2) the same diet supplemented with PLC (710 mumol/kg body wt); 3) L-carnitine (LC; 118 mumol/kg body wt, given in tap water; or 4) a standard diet (containing 56 nmol/g carnitine). A 4-wk constriction of the abdominal aorta caused left ventricular hypertrophy associated with significantly prolonged timing parameters and reduced rate of tension decay in papillary muscles. In group 2, however, PLC treatment prevented hypertrophy-induced changes in these parameters and the reduction in unloaded shortening velocity in skinned trabeculae. Finally, PLC treatment maintained the relative proportion of myosin heavy chain isoforms in left ventricular wall of animals subjected to aortic constriction. Both PLC and LC completely prevented carnitine depletion due to hypertrophy and to dietary restriction. Because LC did not modify papillary muscle contractile function, these results demonstrate that PLC affects hypertrophy-induced changes in muscle mechanics and ventricular wall composition independently of tissue carnitine levels.

Animals↗
PubMed1994

Delayed doxorubicin cardiomyopathy in the rat: possible role of reduced food intake.

The development of delayed doxorubicin cardiomyopathy in the rat is accompanied by profound anorexia, dramatically reducing the caloric intake. To assess the contribution of a restriction in food to the alterations in cardiac function, animals treated with doxorubicin were compared with a group of pair-fed control animals and with a second group of controls with unrestricted access to food. Prolongation of the Q alpha T interval of the electrocardiogram developed in rats treated with doxorubicin, but not in pair-fed controls. Myofibrillar ATPase activity and the contractile strength of isolated papillary muscles were depressed in rats treated with doxorubicin, but not in pair-fed rats. The reduction in ventricular weight was proportional to the reduction in the body weight in pair-fed rats, whereas a higher ratio of ventricular to body weight was observed in rats treated with doxorubicin. These results indicate that the alterations in cardiac function observed in delayed doxorubicin cardiomyopathy are not due to a reduction in the intake of food.

Adenosine Triphosphatases↗
PubMed1992

Effects of Amrinone on shortening velocity, force development and ATPase activity of demembranated preparations of rat ventricular myocardium.

This study analyses the effects of Amrinone (bipyridine derivative with phosphodiesterase inhibitor properties) on the myofibrillar apparatus of rat myocardium. Thin trabeculae were isolated from the right ventricle and chemically demembranated. Force development and shortening velocity were measured during maximal calcium activations (pCa = 4.45) in control conditions and in the presence of 1-3 mM Amrinone. Maximum shortening velocity was obtained both from extrapolation of the force-velocity curve and with the slack test method. Amrinone was found to significantly reduce maximum shortening velocity and force development. Myofibrils and myosin were prepared from rat ventricular myocardium and their ATPase activity was assessed in control conditions and in the presence of Amrinone (0.3-6 mM). Ca-Mg dependent myofibrillar ATPase activity which was determined at low ionic strength was depressed by Amrinone in a dose-dependent way. Ca-stimulated ATPase activity determined at high ionic strength in myofibril or myosin preparations was not affected. Furthermore, Amrinone did not influence the pCa-ATPase activity curve of the myofibrillar preparations. A comparison between the inhibitory effects of Amrinone on myofibrils prepared from euthyroid rats and myofibrils prepared from hypothyroid rats was carried out. The ATPase activity was significantly less depressed in myofibrils prepared from hypothyroid rats than in those prepared from euthyroid rats. These results provide the first evidence of an effect of Amrinone on ATP splitting and force generation in the myofilament system of cardiac muscle.

Adenosine Triphosphatases↗
PubMed1991

[Current role of hysterosalpingography in the assessment of female infertility: review of a series of cases].

The authors reviewed 463 hysterosalpingographies from a series of patients examined for primary infertility. 25.5% of them had been studied with echotomography and 4.1% with therapeutic and explorative laparoscopy. Hysterosalpingographic results were compared with positive findings at clinical examination and with various pathologic associations: the method proved to be extremely valuable in the diagnosis of the primary causes of female infertility, and even showed secondary, sometimes unsuspected, causes--e.g., iatrogenic and inflammatory. Moreover, high agreement (50%) was observed with echotomographic findings. The examination was carried out on an outpatient basis, and proved less dangerous and cheaper than other invasive techniques, its cost being more or less the same as that of US, which however is still the least dangerous and expensive method for the diagnosis of female infertility. Therefore, the authors suggest that diagnostic laparotomy be a second choice and be employed only in the cases where it can have therapeutic purposes. In all the extant cases, combined hysterosalpingography and US are still recommended.

Female↗