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Biomedical subjects

L Ricciardi

Publications and source records attributed to L Ricciardi.

At least 19 recordsLinked to original sources
PubMed1992

CD5+ B lymphocytes and T-cell subsets in a case of juvenile rheumatoid arthritis.

Recent research has demonstrated that CD5+ B lymphocytes have an important role in autoimmune and rheumatic diseases. In a case of juvenile rheumatoid arthritis (JRA), we observed the behavior of these cells and other subpopulations of T lymphocytes of peripheral blood before and after therapy with thymopentin (TP5). All the lymphocyte subpopulations returned to normal range, except the CD5+ B cells, where the percentage remained abnormally high (60%). These data suggest that CD5+ B cells can be a useful monitoring index and confirm their important role in the pathogenesis of juvenile rheumatoid arthritis.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1992

External callus development on ultrasound and its mechanical correlation.

The authors compare the variations in the ultrasonographic and radiographic images with the strain gage values in long bone fractures treated by external fixation. The three test parameters were applied during the entire healing process of 239 fractures. There is a direct correlation between ultrasonographic changes and the calcification of the periosteal callus; there is also a correlation between the morphologic development visible on ultrasound and the stage of the callus. The strain gage values recorded were consistent with these variations.

Biomechanical Phenomena↗
PubMed1990

Night sweats in Hodgkin's disease. A manifestation of preceding minor febrile pulses.

The authors verified the hypothesis regarding an unawareness of possible febrile alterations during night sleep in patients with Hodgkin's disease who complain of night sweats as their only symptom. In these patients, body temperature was monitored by means of a 0.01 degrees C-sensitive linear transducer coupled with a digital multimeter. The palm of the hand (after it was passively closed in a fist by a full bandage) was the body site where temperature measurement was found to be most comfortable for a sleeping patient and independent of movements during sleep. A good correlation was found between the hand temperature taken with this technique and oral temperature. Of six patients with sweating as their only symptom, sweating recurred during the night in four and during the afternoon in the other two. In all patients sweating was preceded by a critical 0.5 to 1.5 degrees C increase in hand temperature, which took place no more than 30 minutes before sweating. Those with nocturnal sweats awakened during the subsequent sweating-related, rapid temperature decrease. These results are consistent with the occurrence of slight unperceived febrile pulses that precede sweating. The only peculiarity of night sweats consists in the higher probability that a preceding slight temperature rise may not be perceived by a sleeping patient, who is more likely to be awakened by the discomfort of the subsequent sweating. This would also explain the small prognostic significance of these sweats, which is the same as that of the preceding fever. These results are discussed in light of the increasing clinical evidence that patients with Hodgkin's disease are often affected by an instability of the thermoregulatory hypothalamic centers.

Adolescent↗
PubMed1990

Evidence for an intrinsic mechanism regulating heart rate variability in the transplanted and the intact heart during submaximal dynamic exercise?

STUDY OBJECTIVE: The aim was to assess the changes in sympatho-vagal balance which occur with exercise. DESIGN: The power spectrum of RR interval fluctuations (low frequency [LF] and high frequency components [HF]) was determined before, during, and after graded work load exercise on a cycle ergometer. The power spectrum of the respiratory signal, oxygen consumption, and respiratory volumes were also evaluated. In all subjects HF was considered to be an index of respiratory sinus arrhythmia. In normal subjects HF and LF were considered to be indices of relative vagal and sympathetic activity, respectively, whereas in heart transplant subjects HF was considered as a respiratory modulation of the intrinsic heart rate, and not dependent on autonomic tone. Heart rate variability was evaluated as RR interval variance. SUBJECTS: 15 normal subjects (six trained cyclists and nine healthy sedentary subjects) and six orthotopic heart transplant recipients took part in the study. MEASUREMENTS AND MAIN RESULTS: During the first part of exercise, heart rate increased, RR interval variance decreased, HF decreased, and the relative amount of LF increased both in sedentary and athletic subjects, suggesting a relative increase in sympathetic tone. However, when approaching peak exercise, while heart rate further increased and the variance slightly decreased, the relative proportion of LF decreased and HF proportionally increased. At peak exercise HF accounted for 99.9% of heart rate variability in athletic subjects and for 88.9% in sedentary subjects (p less than 0.001 v baseline and v LF in both groups). In heart transplant subjects both the variance and the HF increased from the beginning of exercise (p less than 0.05), and showed a direct correlation with ventilatory variables and an inverse correlation with heart rate (r = 0.794, p less than 0.001, multiple regression analysis). No measurable LF components could be obtained in these subjects. During recovery, while the heart rate decreased and the RR interval variance increased, there was a relative increase in LF and a relative decrease in HF in normal subjects (either sedentary or athletic). Similarly, in heart transplant subjects, there was a decrease in HF during recovery. Thus the increase in HF at peak exercise in normal subjects contrasts with all the other data which suggest a prevalence in sympathetic tone during the entire exercise and the early recovery period, but appears similar to the increase in HF observed in heart transplant subjects due to the effect of increased ventilation during exercise. CONCLUSIONS: These findings suggest that at peak exercise a non-autonomic mechanism, possibly intrinsic to the heart muscle, may determine heart rate fluctuations in synchrony with ventilation in the intact as well as in the denervated human heart.

Adolescent↗
PubMed1987

Relation between ventricular DNA content and number of myocytes and non-myocytes in hearts of normotensive and spontaneously hypertensive rats.

Myocardial DNA concentration and ventricular weight were measured in the hearts of normal and spontaneously hypertensive rats varying in age from 1 day to 1 year and the ventricular DNA content calculated. A linear relation between ventricular DNA content and ventricular weight was observed in both rat strains. This linear relation was deduced theoretically, assuming that the number of ventricular non-myocytes per heart was proportional to ventricular weight and that the number of ventricular myocytes per heart was constant after the first postnatal week. The fit with experimental data produced values of the number of ventricular myocytes (42.5 X 10(6] and non-myocytes (199 X 10(6) per gram of ventricular tissue) in normal rat heart. Using published data on ventricular volume occupied by myocytes (80%) and myocardial specific density (1.06 g X ml-1), the mean(SD) volume of individual myocytes could be calculated (17758(2632) multiplied by ventricular weight, expressed in micron 3 X g). The values obtained compared well with experimental observations reported in the present study (18504(131) micron 3 X g) and in other studies. Hearts from spontaneously hypertensive rats had lower numbers of myocytes (37.4 X 10(6] and non-myocytes (180 X 10(6) per gram) per heart than normal hearts with identical ventricular weights. Hearts of normal 2 month old rats that were made hypertrophic by various means were identical to non-hypertrophic hearts of normal older rats with identical ventricular weights in relation to the number of ventricular myocytes and non-myocytes per heart. It is concluded that ventricular hypertrophy induced in young adult rats might be regarded as normal growth occurring at an accelerated rate.

Animals↗
PubMed1987

Uncemented hip prosthesis: a new screw stem model with a review of 73 cases.

A new uncemented prosthetic stem based on a screw system is presented. The biomechanical, metallurgic and technical principles on which this innovation is based are discussed. The indication and surgical technique are described and 73 cases are reported. The new stem is easy to apply and makes it possible to regulate anteversion precisely, and above all, to satisfy the preconceived biomechanical requirements. Some cases with a shorter follow-up are included because we allowed a suitable time lapse after our earlier cases before extending our indication. However, there is considerable documentation of screw stems in the literature on the long term toleration of screw stems.

Adult↗
PubMed1986

Effects of acidosis on force-sarcomere length and force-velocity relations of rat cardiac muscle.

The effect of hypercapnic acidosis was compared with that of lowering extracellular calcium concentration ([Ca++]o) in rat cardiac trabeculae. The relations between force and sarcomere length and between force and velocity were studied. Sarcomere length was measured by means of laser diffraction techniques and sarcomere shortening velocity by means of isovelocity releases. The curve representing the relation between force and sarcomere length shifted from convex towards the ordinate (pH 7.35) to convex towards the abscissa (pH 6.68) as after [Ca++]o had been reduced from 1.5 to 0.3 mmol X litre-1. Increasing [Ca++]o at low pH from 1.5 to 4.0 mmol X litre-1 allowed the shape of the relation to be restored, but force values failed to return to control values. The relation between force and pH over the range 6.22-7.94 was also tested. During steady low pH maximum unloaded sarcomere shortening velocity was not significantly different from control values whereas it was decreased at low [Ca++]o. Under both conditions maximum isometric tension (Po) was reduced. The results are consistent with the hypothesis that H+ ions cause a shift of the force-p Ca curve to the right at all sarcomere lengths, as a result of competition between Ca++ and H+ ions for binding to the myofilaments.

Acidosis, Respiratory↗
PubMed1986

Comparison between the sarcomere length-force relations of intact and skinned trabeculae from rat right ventricle. Influence of calcium concentrations on these relations.

To investigate the extent to which the properties of the cardiac myofibrils contribute to the length-force relation of cardiac muscle, we determined the sarcomere length-force relations for rat ventricular trabeculae both before and after the muscles were skinned with the detergent Triton X-100. Sarcomere length was measured continuously by laser diffraction. In the unskinned trabeculae stimulated at 0.2 Hz, the relation between active force and sarcomere length at an extracellular calcium concentration of 1.5 mM was curved away from the sarcomere length axis, with zero force at sarcomere length of 1.5-1.6 micron. At 0.3 mM calcium, the sarcomere length-force relation was curved toward the sarcomere length axis. Chemical skinning of the muscle with 1% Triton X-100 in a "relaxing solution" caused an increase in intensity and decrease in dispersion of the first order diffraction beam, indicating an increased uniformity of sarcomere length in the relaxed muscle. During calcium-regulated contractures in the skinned muscles, the central sarcomeres shortened by up to 20%. As the calcium concentration was increased over the range 1-50 microM, the relation between steady calcium-regulated force and sarcomere length shifted to higher force values and changed in shape in a manner similar to that observed for changes in extracellular calcium concentration before skinning. The sarcomere length-force relations for the intact muscles at an extracellular calcium concentration of 1.5 mM were similar to the curves at calcium concentration of 8.9 microM in the skinned preparations, whereas the curves at an extracellular calcium concentration of 0.3 mM in intact muscles fell between the relations at calcium concentrations of 2.7 and 4.3 microM in the skinned preparations. A factor contributing to the shape of the curves in the skinned muscle at submaximal calcium concentrations was that the calcium sensitivity of force production increased with increasing sarcomere length. The calcium concentration required for 50% activation decreased from 7.71 +/- 0.52 microM to 3.77 +/- 0.33 microM for an increase of sarcomere length from 1.75 to 2.15 micron. The slope of the force-calcium concentration relation increased from 2.82 to 4.54 with sarcomere length between 1.75 and 2.15 micron. This change in calcium sensitivity was seen over the entire range of sarcomere lengths corresponding to the ascending limb of the cardiac length-force relation. It is concluded that the properties of the cardiac contractile machinery (including the length-dependence of calcium sensitivity) can account for much of the shape of the ascending limb in intact cardiac muscle.

Animals↗
PubMed1986

Ultrasonography in the evaluation of osteogenesis in fractures treated with Hoffmann external fixation.

The possibilities of ultrasonography demonstrating periosteal callus and osteogenesis at the fracture focus are described. Illustrative cases are presented and the advantages of this technique are discussed. It is emphasized that ultrasonography is a noninvasive technique that may be repeated as often as is necessary. It provides images of appositional periosteal callus much earlier than radiography, thus facilitating early evaluation of the treatment employed.

Femoral Fractures↗
PubMed1985

"Interpotential" mounting in monolateral Hoffmann fixation.

The authors carried out an experimental study to quantify the stability of monolateral fixation devices of the Hoffmann type. The technical tests indicated that changes were needed in the geometry of the devices; these were achieved by designing a junction piece which enables the transfixion pins and the smooth stabilization rod to remain in the same plane, while leaving the rest of the instrumentation unchanged. The use of this component makes the fixation device more stable and lighter than the classic monolateral devices commonly used. It also prevents the separation and rotation of the fragments that can occur when rods not in the same plane are subjected to compression.

Biomechanical Phenomena↗
PubMed1984

Age-dependent variations of diastolic stiffness and collagen content in rat ventricular myocardium.

A parallel investigation on collagen content and diastolic mechanical properties has been performed on myocardial specimens isolated from male albino Wistar rats of different age groups (1-5 days, 10-20 days, 2 months, 8 months, 18 months, 24-26 months). Total water content, inulin-distribution space, protein concentration were determined together with hydroxyprolin content of the tissue. Mechanical properties of isolated papillary muscles were characterized in terms of static, dynamic, and plastic response to strain. During maturation (from birth to 2 months) the increase of collagen content is paralleled by an increase of static elasticity and by a reduction of plasticity. During maturity (2-8 months) and ageing (8-26 months) the collagen concentration in myocardial tissue still increases, but this change is associated to a reduction of the static components and to an increase of dynamic components of myocardial stiffness. A comparison between specimens from right and left ventricular myocardium indicates that a higher collagen content in the right ventricle is associated with a higher static elasticity.

Aging↗
PubMed1982

Inulin uptake and washout in contracting and quiescent rat papillary muscle.

Equilibration and washout curves of inulin were determined in isolated rat papillary muscles. Inulin uptake did not reach a steady-state value even after a long equilibration time. The effects of contractile activity were investigated. Isometric contractions increased the rate of inulin uptake and washout. In isotonic conditions, a smaller increase in the uptake and washout was observed. These changes could be attributed to an actual increase of inulin distribution space and/or to an accelerated diffusion kinetics.

Animals↗
PubMed1979

[Visco-elastic characteristics of the rat aorta].

In order to estimate wave propagation "in vitro", aortic compliance has been studied by means of rings and stripes from 6 adult male Wistar rats. Lengthening and shortening maneuvres have been performed; the pulse transmission rate was evaluated by calculating the elastic modulus during the maneuvres. A Norepinephrine infusion has been done. Results obtained show that transmission rate is higher in shortening than in lengthening phases. Norepinephrine did not significantly affect the values. The rate values were not greatly different whether "in vitro" or "in vivo". By increasing specimen stress, the rate too was increased, but the amount was lower than "in vivo" values. Hence it was assumable that rate variations "in vivo", should be partially influenced by elastic modulus, and a vegetative intervention should be implied.

Animals↗
PubMed1979

[Measurement of the velocity of the pulse wave].

Pulse wave transmission rate has been measured "in vivo" in 6 male anaesthetized Wistar rats, by means of cannulae, inserted both in carotid and femoral arteries. The measure has been done by calculating the time delay of several corresponding levels in the two pressure pulses: at the foot, during the ascending phase, at the peak. Three different intervention have been carried out: Ach, NA, blood transfusion. The transmission rate outcame higher at the pulse foot than at the peak, in control animals and in Ach and blood transfusion interventions. The NA intervention inverted this behaviour, where the increase in transmission rate did not correspond to the rate of pressure growing. The possible influences of a vegetative component on arterial viscoelastic behaviour are discussed.

Acetylcholine↗
PubMed1978

Influence of internal shortening on time course of active state in rat papillary muscle.

In order to investigate internal shortening effects upon time course of active state, a study on rat papillary muscle has been carried out. Internal (or CE) shortening was evaluated according to a mechanical muscle model in which parallel elastic (PE), series elastic (SE), contractile (CE) elements are represented. CE force-velocity-shortening-time relationships have been used to describe time course of muscle active state in isometric, completely isotonic, afterloaded, and stopped isotonic contractions. The results obtained suggest that, regardless of type of contraction utilized, the parameters of muscle active state are strongly influenced by the amount of CE shortening.

Animals↗