Search PubMed⌕ Search

Biomedical subjects

G Cerri

Publications and source records attributed to G Cerri.

At least 19 recordsLinked to original sources
PubMed2004

Macaque ventral premotor cortex exerts powerful facilitation of motor cortex outputs to upper limb motoneurons.

The ventral premotor area (F5) is part of the cortical circuit controlling visuomotor grasp. F5 could influence hand motor function through at least two pathways: corticospinal projections and corticocortical projections to primary motor cortex (M1). We found that stimulation of macaque F5, which by itself evoked little or no detectable corticospinal output, could produce a robust modulation of motor outputs from M1. Arrays of fine microwires were implanted in F5 and M1. During terminal experiments under chloralose anesthesia, single stimuli delivered to M1 electrodes evoked direct (D) and indirect (I1,I2, and I3) corticospinal volleys. In contrast, single F5 shocks were ineffective; double shocks (3 msec separation) evoked small I waves but no D wave. However, when the test (T) M1 shock was conditioned (C) by single or double F5 shocks, there was strong facilitation of I2 and I3 waves from M1, with C-T intervals of <1 msec. Intracellular recordings from 79 arm and hand motoneurons (MNs) revealed no postsynaptic effects from single F5 shocks. In contrast, these stimuli produced a robust facilitation of I2 and I3 EPSPs evoked from M1 (60% of MNs); this was particularly marked in hand muscle MNs (92%). Muscimol injection in M1 reduced I waves from F5 and abolished the F5-induced facilitation of late I waves from M1, and of EPSPs associated with them. Thus, some motor effects evoked from F5 may be mediated by corticocortical inputs to M1 impinging on interneurons generating late corticospinal I waves. Similar mechanisms may allow F5 to modulate grasp-related outputs from M1.

Animals↗
PubMed2003

Facilitation from ventral premotor cortex of primary motor cortex outputs to macaque hand muscles.

We demonstrate that in the macaque monkey there is robust, short-latency facilitation by ventral premotor cortex (area F5) of motor outputs from primary motor cortex (M1) to contralateral intrinsic hand muscles. Experiments were carried out on two adult macaques under light sedation (ketamine plus medetomidine HCl). Facilitation of hand muscle electromyograms (EMG) was tested using arrays of fine intracortical microwires implanted, respectively, in the wrist/digit motor representations of F5 and M1, which were identified by previous mapping with intracortical microstimulation. Single pulses (70-200 microA) delivered to F5 microwires never evoked any EMG responses, but small responses were occasionally seen with double pulses (interval: 3 ms) at high intensity. However, both single- and double-pulse stimulation of F5 could facilitate the EMG responses evoked from M1 by single shocks. The facilitation was large (up to 4-fold with single and 12-fold with double F5 shocks) and occurred with an early onset, with significant effects at intervals of only 1-2 ms between conditioning F5 and test M1 stimuli. A number of possible pathways could be responsible for these effects, although it is argued that the most likely mechanism would be the facilitation, by cortico-cortical inputs from F5, of corticospinal I wave activity evoked from M1. This facilitatory action could be of considerable importance for the coupling of grasp-related neurons in F5 and M1 during visuomotor tasks.

Animals↗
PubMed2001

Coordination of coupled hand and foot movements during childhood.

To acquire further insight into the neural mechanisms governing the association of voluntary oscillations of ipsilateral hand and foot we investigated when and how coordination of such coupling develops in children 7-10 years old. Sixty-six children were asked to rhythmically oscillate their right hand and foot, paired in-phase or anti-phase (i.e. rotating in the same or in the opposite angular direction). Angular displacement was monitored by a potentiometric technique, and EMGs from extensor carpi radialis (ECR) and tibialis anterior (TA) were recorded. All subjects were able to couple in-phase oscillations, but 13 of them failed to perform the anti-phase task. Maximal frequency of oscillation was found to be positively correlated with age. Phase-relations between hand and foot oscillations and between onsets of the EMG activity in hand and foot movers were measured in 37 of the children. During in-phase coupling limb oscillations were kept in an almost perfect synchrony by three different modalities of muscle recruitment. Ten of the youngest children activated TA before ECR, while 13 of the oldest subjects activated ECR before TA, as do adults. The remaining 14 children (7-8 years old) activated the two muscles almost synchronously. During anti-phase coupling, most of the younger children (20) showed a strict phase-opposition between both EMG onsets and movements. The remaining 10 (9-10 years old) activated the ECR first. The hand frequency-response (i.e. the phase-relation between the onset of the EMG and the related movement) showed age-related changes, corresponding to the behaviour of a mass-spring model (with lumped parameters) decreasing its resonant frequency. Instead, the foot frequency-response remained unchanged. The age-related modifications of the hand frequency-response adequately explain the changes of the interlimb relations described above. These results show that central structures controlling hand and foot coupling are still immature before 10 years of age and reinforce the view that in-phase and anti-phase coupling require separate neural controls.

Adult↗
PubMed1998

Motoneuronal pre-compensation for the low-pass filter characteristics of muscle. A quantitative appraisal in cat muscle units.

1. The relevance of motoneurone dynamic sensitivity in compensating for the low-pass filter properties of muscle was assessed by stimulating cat muscle units (MUs) with impulse discharges generated by two current-to-rate converters: (i) a spinal motoneurone, sensitive to both the input intensity and its first derivative, and (ii) a linear current-to-rate converter, i.e. a neurone model with the same static sensitivity as the motoneurone but lacking dynamic sensitivity. 2. Discharges generated by injection of sine-wave currents in three motoneurones of the 'fast' type and in the three related model versions were applied to the axon of forty-six MUs. The MU isometric tension was modulated at the frequency of the current sine wave (0.5-20 Hz). Phase and gain of the current-to-force transduction were measured. 3. When MUs were driven by the model, the force lagged the current by 90 deg at 1 Hz in slow MUs and at around 5 Hz in fast MUs. Under motoneurone drive, the 90 deg phase lag was attained at frequencies about twice as high. 4. The gain of the transduction (peak-to-peak force modulation/peak-to-peak current modulation) decayed when the modulation frequency was increased. In all but five units, the cut-off frequency, Fco (gain attenuated by -3 dB), was higher when the unit was motoneurone driven (FcoCell) then when it was model driven (FcoMod). In both conditions, Fco was inversely correlated with the MU's time-to-peak. The advantage conferred by the motoneurone dynamic sensitivity was expressed by the Fco ratio (FcoCell/FcoMod). Across the MU population this ratio ranged from 0. 6-2.8, was inversely correlated with the time-to peak, and was directly correlated with the half-tension rate, i.e. the impulse rate at which MUs develop 50 % of their maximal tetanic force. The largest improvement (Fco ratio > 2.0) was found in units with mechanical features similar to those presumably coupled 'in vivo' to the motoneurones utilized for stimulation. 5. This estimate was confirmed in experiments in which trains of pulses, generated by injection of ramp currents in another motoneurone and the related model, were used to activate eight MUs, selected for being similar to that connected 'in vivo' to the motoneurone. As expected, for any given current slope the rising phase of isometric tension was steeper when units were motoneurone driven than when they were model driven. The gain (force slope/current slope) was plotted against the ramp slope to identify the cut-off slope, Sco, at which the gain was attenuated by -3 dB. In this homogeneous MU sample, the ratio expressing the advantage of the motoneurone drive (ScoCell/ScoMod, equivalent to the Fco ratio), ranged from 2.62-2.97, values comparable with those observed in sine-wave experiments when the motoneurone and muscle units were properly matched.

Animals↗
PubMed1997

Normal high energy phosphate ratios in "stunned" human myocardium.

OBJECTIVES: We sought to investigate whether alterations in cardiac high energy phosphates occur in postischemic "stunned" human myocardium. BACKGROUND: Transient postischemic myocardial dysfunction is a common phenomenon that occurs in a variety of clinical settings in the absence of necrosis, and its pathogenesis is still unclear. Cardiac high energy phosphates are reduced during ischemia, and persistently altered myocardial high energy phosphate metabolism has been suggested as a mechanism contributing to stunning. METHODS: We studied 29 patients with a first anterior myocardial infarction (MI) who underwent successful reperfusion within 6 h of the onset of chest pain. These patients underwent 31P magnetic resonance spectroscopy (MRS) a mean of 4 days after MI for measurement of left ventricular contractility and relative high energy phosphate metabolites. Twenty-one patients underwent a second 31P MRS study a mean of 39 days after MI. Eight volunteers served as control subjects. RESULTS: Global and infarct area wall motion scores improved significantly between the early and late studies. No difference was found between early cardiac phosphocreatine (PCr)/beta-adenosine triphosphate (beta-ATP) ratios in patients and control subjects ([mean +/- SD] 1.51 +/- 0.17 vs. 1.61 +/- 0.18, respectively, p = 0.17) or between early and late study results in patients (1.51 +/- 0.17 vs. 1.53 +/- 0.17, respectively, p = 0.6). For alpha of 0.05, the study had a 90% power to detect a 9% difference. CONCLUSIONS: The results of this study demonstrate normal myocardial PCr/ATP ratios in patients with myocardial stunning after reperfusion and suggest that relative cardiac high energy phosphates are not depleted in stunned human myocardium.

Adenosine Triphosphate↗
PubMed1996

[Effects of rejection on the contractile reserve of the graft after heart transplantation].

PURPOSE: To test the hypothesis that rejection could affect the contractility and contractile reserve of left ventricle after heart transplantation. METHODS: Echocardiographic parameters and noninvasive blood pressure end-systolic pressure (ESP), heart rate (HR), end diastolic (EDV) and end-systolic (ESV) volumes, ejection fraction (EF), end-systolic stress (ESS) and the end-systolic relation (ESS/ESV) were recorded in 68 studies in 11 patients, seven days-12 months after heart transplantation. Accordingly with the endomyocardial biopsies results were divided into two groups: group A-with no rejection (53 studies), and group B-with rejection (15 studies). RESULTS: The nitroprusside infusion changed significantly and in the same way, all the parameters except the ESS/ESV ratio (A = 5.5 +/- 1.7 x B = 4.8 +/- 1.5 g/cm2/mL, p = NS); there was a decrease in ESP (A = 107 +/- 15 and B = 109 +/- 12 mmHg, p = NS), EDV (A = 68 +/- 19 and B = 81 +/- 12 mL, p = NS), ESV (A = 12 +/- 5 and B = 18 +/- 12 mL, p = NS) and ESS (A = 59 +/- 13 and B = 82 +/- 20g/cm2, p = NS); there was an increase in HR (A = 94 +/- 9 and B = 93 +/- 16bpm, p = NS) and EF (A = 83 +/- 5 and B = 79 +/- 8%, p = NS). In the dobutamine study it was observed differences for both groups, except for ESP (A = 156 +/- 26 and B = 149 +/- 26mmHg, p = NS). The increase in HR, EF and ESS/ESV ratio was greater in group A (HR-A = 117 +/- 19 and B = 102 +/- 25bpm, p < 0.05; EF-A = 91 +/- 4 and B = 78 +/- 11%, p < 0.05; ESS/ESV-A = 13.1 +/- 6 and B = 6.1 +/- 3.1 g/cm2/mL, p < 0.05). For group A it was smaller the EDV (57 +/- 18 x 94 +/- 35 mL, p < 0.05), ESV (5 +/- 3 x 24 +/- 20 mL, p < 0.05) and ESS (57 +/- 21 x 102 +/- 40 g/cm2, p < 0.05). CONCLUSION: Rejection may not induce changes in resting left ventricular contractility, however, the contractile reserve is depressed during an episode of moderate to severe rejection.

Adult↗
PubMed1996

[Acute effects of ibopamine on left ventricular mechanics and contractility in patients with idiopathic dilated cardiomyopathy].

PURPOSE: The effects of ibopamine (IBO) on left ventricular (LV) mechanics and contractility have not been described. The aim of this study was to test the hypothesis that IBO has a contractile effect at a dose of 200 mg. METHODS: Ten male patients (43 +/- 7 years) with refractory heart failure due to idiopathic dilated cardiomyopathy were studied. The patients were submitted to simultaneous echo-Doppler and hemodynamic (microtip catheter) studies, before (B) and after (20, 40 and 60 minutes) a dose of 200 mg of IBO. LV pressure/diameter and stress/strain relations were obtained. Subsequently, heart rate (HR-bpm), cardiac output (CO-L/m), end-diastolic pressure (EDP-mmHg); fractional shortening (FS-%); maximal elastance (Emax-mmHg/cm/s); end systolic (ESS-g/cm2) and end-diastolic (EDS-g/cm2) stress; chamber (Kp-mmHg/cm) and muscle (K(m)-g/cm2) stiffness, and the time of constant relaxation (Tau-ms) were analyzed. RESULTS: Results were presented as mean +/- standard deviation for conditions before and after IBO (20, 40 and 60 minutes) respectively. There was no change in HR (99 +/- 7; 100 +/- 7; 99 +/- 8; 99 +/- 10). Significant increases were observed in CO (4.13 +/- 1.28; 4.95 +/- 1.38; 5.13 +/- 1.86; 5.18 +/- 1.57), FS (13.7 +/- 2.4; 15.4 +/- 2.8; 15.9 +/- 1.8; 16.1 +/- 2.0), and Emax (14.8 +/- 3.2; 16 +/- 3.6; 17.7 +/- 4.2; 17.6 +/- 4.2). A transient (20 minutes) increase followed by a decrease (40 and 60 minutes) occurred in EDP (26.3 +/- 4.2; 30.6 +/- 6.4; 24.6 +/- 5.6; 22.3 +/- 4.6), EDS (79.7 +/- 22.8; 91.7 +/- 29.6; 79 +/- 31; 63 +/- 17.3), and Kp (27.2 +/- 12.6; 60 +/- 26.7; 27.9 +/- 11.7; 28.1 +/- 11). CONCLUSION: IBO has a beneficial effect on LV systolic and diastolic function as well as on contractility in patients with heart failure due to idiopathic dilated cardiomyopathy.

Adult↗
PubMed1996

[Effects of partial ventriculectomy on left ventricular mechanical properties, shape, and geometry in patients with dilated cardiomyopathy].

PURPOSE: To investigate the short-term effects of the partial ventriculectomy (resection of lateral wall associated to mitral annuloplasty) on cardiac mechanics, contractility, shape and geometry of the left ventricle (LV). METHODS: Eleven male patients with severe congestive heart failure due to dilated cardiomyopathy were studied. The mean age was 51 +/- 7 years and the functional class was III (five patients) or IV (six patients) before the surgery. Patients were evaluated before and at 17 +/- 4 days after the surgery by simultaneous LV pressure and echocardiographic data. End-diastolic pressure (EDP-mmHg), wall stress (EDS-g/cm2) and diameter (EDD-cm); endsystolic wall stress (ESS) and diameter (ESD), fractional shortening (FS-%) and maximal elastance (Emax-mmHg/ cm/s); the diastolic slope of the pressure-diameter (Kp-mmHg/cm) and stress-strain (Km-g/cm2) loops; shape (L/ EDD, adimensional, where L is the LV long axis) and geometry (Th/EDD, adimensional, where TH is the LV diastolic thickness) were obtained. RESULTS: 1) The ressected muscle fragments (diamond shape) were 10.8 +/- 1.3 cm in length and 5 +/- 0.6 cm in width; 2) all patients were discharged from hospital (15-29 days) in class I (eight cases), II (two), and III (one); 3) it was observed a decrease in EDP (24.3 +/- 7.7 x 17.5 +/- 3.2, p = 0.016); in EDD (8.0 +/- 0.7 x 7.2 +/- 0.8, p = 0.002); in EDS (57.9 +/- 26.8 x 37.4 +/- 19.2, p = 0.005); in ESS (199 +/- 46.9 x 102.8 +/- 33.1, p = 0.004); in ESD (7.1 +/- 0.7 x 5.7 +/- 0.8, p < 0.001); in Kp (22.3 +/- 15.9 x 11.5 +/- 6.9, p = 0.014); and in K(m) (467.4 +/- 212 x 214.6 +/- 87.4, p = 0.01); and, 4) it was noted an increase in FS (11.5 +/- 1.8 x 19.8 +/- 3.9, p < 0.001); in Emax (13.8 +/- 2.2 x 18.6 +/- 3.2, p < 0.001); and in L/EDD (1.32 +/- 0.1 x 1.47 +/- 0.13, p < 0.007) and Th/Dd (0.11 +/- 0.04 x 0.17 +/- 0.08, p < 0.038). CONCLUSION: The partial ventriculectomy showed multiple significant beneficial effects in these dilated myopathic hearts.

Adult↗
PubMed1995

[Assessment of the myocardial functional reserve in patients with left ventricular aneurysm by radionuclide ventriculography. Response to isotonic exercise].

PURPOSE: To evaluate global and regional left ventricular (LV) ejection fractions (EF) by radionuclide ventriculography in patients with LV aneurysm at rest and during isotonic exercise. METHODS: Twenty patients were studied by radionuclide ventriculography at rest and during exercise. All patients had been submitted to cineangiography and showed LV aneurysm post myocardial infarction. RESULTS: Patients were divided according to LV EF in two groups: one with EF > or = 40% and the other with < 40% EF. Both groups showed normal response of global EF to exercise: mean rest EF was 40 +/- 14% and mean exercise EF was 45 +/- 14% (p < 0.01). When groups were considered separately, EF values showed the same behavior. Half of the patients showed normal response to exercise and the other half showed abnormal response. These changes were not associated with resting EF values, but were due to regional EF of lateral wall, that changed from 44 +/- 7 to 48 +/- 7% in the group of patients with normal LV EF response to stress and from 50 +/- 5 to 46 +/- 5% in those with abnormal response (p < 0.01). CONCLUSION: The evaluation of regional ventricular EF by radionuclide ventriculography during exercise better discriminates functional reserve in patients with LV aneurysm than resting global EF. These findings could help the decision making of the therapeutic approach in this specific group of patients.

Aged↗
PubMed1993

[The repair of inguinal and/or crural hernias with giant Mersilene prostheses in the preperitoneal position].

The authors present 44 patients operated for hernias (inguinal and/or femoral) with a median pre-peritoneal approach positioning a mersilene mesh with Stoppa's technique. The results are very interesting considering that the hernias treated are all at high risk of recurrence. We had 4 complications (1 bleeding and 3 wound infections) that were conservatively treated, no mortality at all. The follow-up was of 12 months (mean) and no recurrence was discovered.

Aged↗
PubMed1991

[Magnetic resonance imaging in study of the temporo-mandibular joint. II. Pathologic findings].

A total of 107 temporomandibular joints (TMJ) were examined with two superconductive MR units at 1T and 1.5T. In 73 TMJs, MR revealed 55 disk displacements, 7 disk perforations, 10 joint space adhesions, 33 osteoarthrities, 3 avascular necroses of the mandibular condyle, and 25 joint effusions. These abnormalities are described and discussed. In spite of some limitations--e.g., motion artifacts and patients' claustrophobia--MR imaging is the procedure of choice in abnormal TMJs, because it yields useful information as to therapeutic choice (conservative versus surgical). Arthrography can be used as a complementary study technique in the patients with marked disagreement between clinical and MR findings. Arthroscopy should be used as a surgical procedure in abnormal TMJs selected by previous MR studies.

Adolescent↗
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↗
PubMed1988

Management of cervical cancer and surgical-pathological staging (SPS). Report of our clinical case series.

FIGO staging is imprecise in a relevant number of cases of cervical cancer, especially in advanced stages, when the prognosis and the choice of the therapy are most delicate. The Authors examine their case series about the index of correction of FIGO staging after Surgical Pathological Staging (SPS). Surgical Pathological Staging was applied systematically in 788 cases and revealed errors in FIGO staging in 16% of cases at stage I; 77% at stage II; and 96% at stage III. SPS allows a more precise knowledge of neoplastic diffusion and consequently to the elimination of many false advanced stages and to adequate the treatment. Furthermore 5 year survival rate confirms the role of SPS and Surgical therapy alone or combined with Radiotherapy and Chemotherapy in every stages of diffusion of cervical cancer.

Female↗