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Biomedical subjects

R Massa

Publications and source records attributed to R Massa.

At least 73 records · Page 4Linked to original sources
PubMed1992

Active muscle length reduction progressively damages soleus in hindlimb-suspended rabbits.

This study describes the morphologic changes in rabbit soleus muscle following hindlimb suspension (HS) for 1 to 4 weeks (group A); or following HS with hindfeet passively dorsiflexed, by means of an elastic band, for 1 to 2 weeks (group B). In the latter, elastic band use allowed phasic contractions of foot extensor muscles against resistance and prevented 35% chronic soleus shortening, which occurred in group A animals. In group A, the soleus revealed progressive muscle atrophy and myofibrillar damage. Myofibrils underwent dissolution, muscle regeneration was ineffective, and adipose tissue developed from about 2-week suspension onward. Conversely, passive dorsiflexion of unloaded hindfeet was essential in maintaining mass and structural muscle integrity in the soleus of group B. It is hereby demonstrated that HS-induced soleus damage in the rabbit is progressive, and can be prevented, avoiding long-term shortening of soleus and its phasic unloaded contractions. Soleus sensitivity to unloading conditions, such as HS, tenotomy, and hypogravity, may depend on the particular physiology of this tonic antigravity muscle, engaged mainly in developing long-lasting isometric contractions in a stretched length.

Animals↗
PubMed1992

Loss and renewal of thick myofilaments in glucocorticoid-treated rat soleus after denervation and reinnervation.

Denervation of rat soleus muscle and simultaneous administration of high doses of corticosteroids for 7 days caused marked muscle fiber atrophy and selective loss of thick myofilaments from many muscle fibers by light and electron microscopy. Myosin heavy chain/actin ratios were greatly reduced on polyacrylamide gel electrophoresis. Nerve crush instead of cut permitted reinnervation after 2 weeks and demonstrated the reversibility of the muscle changes within a week after reinnervation. There was formation of new thick filaments and their reintegration into myofibrils without further breakdown, although large areas of Z-disc streaming appeared. The mechanism of A-band breakdown remains obscure, but it presumably starts with limited proteolysis and continues with disaggregation of myosin molecules. This is consistent with our observation that the muscle fibers retain a relatively good reactivity to antibodies against myosin heavy chain 1 week after denervation and corticosteroid administration. A syndrome recalling these experiments is seen in severely asthmatic patients receiving corticosteroids and pharmacologically paralyzed for mechanical respiration.

Actin Cytoskeleton↗
PubMed1991

Epileptic activity following cerebral ischemia in Mongolian gerbils is depressed by CPP, a competitive antagonist of the N-methyl-D-aspartate receptor.

A 10-min bilateral carotid occlusion (BCO) in Mongolian gerbils induces transient generalized epileptic discharges in the hippocampal and cortical regions, which are followed by long lasting interictal spiking activity. An initial peak of this activity occurs within 18-36 h after BCO, then it decreases slowly and completely disappears by the 6th-7th day. On the 7th day, morphological evidence shows a selective loss of CA1 hippocampal neurons. 4-(3-Phosphonopropyl)-2-piperazine-carboxylic acid (CPP), a competitive antagonist of the N-methyl-D-aspartate (NMDA) receptor was administered (7 or 15 mg/kg i.p.) immediately after clamping, and again every 12 h for 3 consecutive days. It induced a dose-related depression of epileptic activity, while, on the other hand, at both dosages, it always prevented the loss of CA1 neurons. The results are discussed in view of the different mechanisms mediating cell damage and epileptic activity.

Animals↗
PubMed1991

Familial inclusion body myositis among Kurdish-Iranian Jews.

We report two cases of adult-onset, slowly progressive limb-girdle muscle weakness with a remarkable sparing of quadriceps muscles that developed in patients from different families of Iranian-Kurdish-Jewish origin. Each patient had a similarly affected sibling. The findings by means of muscle biopsies showed abnormalities typical of inclusion body myositis, including abundant lined vacuoles and characteristic cytoplasmic inclusions of 15- to 18-nm filaments. Remarkably, many vacuolated muscle fibers showed immunoreactivity to neural cell adhesion molecule, a fetal muscle antigen. The common origin of these patients from an isolated ethnic group with frequent consanguinity and the familial incidence is indicative of a genetic causation or predisposition, probably with an autosomal recessive inheritance. This familial myopathy is one of several clinical syndromes that share the typical pathological findings of inclusion body myositis. The pathogenic relationship between these different familial forms and the more common sporadic form of inclusion body myositis is not known.

Adult↗
PubMed1991

Myofibrillar disruption in the rabbit soleus muscle after one-week hindlimb suspension.

Relevant muscle- and species-specific differences may be found in the reaction of muscles to hindlimb suspension. This problem has been studied in 5 rabbits following a one-week hindlimb suspension, and in 5 ground-based controls. The soleus and the tibialis were prepared for light and transmission electron microscopy. In suspension the animals occasionally extended and flexed the hindlimbs, but, when standing still, their hindfeet were plantar-flexed to an angle of 180 degrees. In this position the length of the soleus was determined to be 35% less than in controls, whereas that of the tibialis was 30% more. Histologically, the tibialis fibers usually exhibited a preserved sarcomeric pattern, whereas soleus fibers displayed a regular sequence of areas of shortened sarcomeres, alternating with areas of myofibrillar disruption. These findings demonstrated that hindlimb suspension induces a focal breakdown of the soleus myofibrils, probably dependent on the reduced longitudinal tension of the suspended soleus and its phasic contractions against no load. It is conceivable that similar factors could also be responsible for soleus muscle atrophy induced by hypogravity as well as by other clinical conditions during which a stressful plantar flexion of the feet occurs against no load.

Animals↗
PubMed1991

Glucocorticoids and immunosuppressants do not change the prevalence of necrosis and regeneration in mdx skeletal muscles.

Therapeutic doses of methylprednisolone, azathioprine, cyclosporin A, and cyclophosphamide administered to mdx mice between 15 and 45 days of age failed to significantly influence the time course and prevalence of necrosis and regeneration or serum creatine kinase activity. This finding contrasts with previously reported findings of beneficial effects of glucocorticoids in Duchenne muscular dystrophy (DMD). This may indicate that, mechanisms upon which beneficial effects of glucocorticoids depend in DMD, do not operate (sufficiently) in mdx mice.

Animals↗
PubMed1991

Bilateral carotid occlusion in normotensive rats: olds facts and new observations.

This work describes that prolonged mild cerebral ischemia may lead to either general or regional derangement of brain morphofunctional integrity. Normotensive adult Wistar rats were used. Under anesthesia with volatile agents or thiopental, the common carotid arteries were ligated permanently. In one group of animals local cerebral blood flow (1CBF) was measured two hours after carotid occlusion using the [14C]iodoantipyrine method. The other carotid-occluded animals were used for clinical rating and histological evaluation, which was performed two days to 4 weeks after surgical operation. The [14C]iodoantipyrine method showed widespread reduction in the cerebral circulation of carotid-occluded animals. Several hours after carotid occlusion, 40% of the animals showed dramatic neurological signs and died on the day of operation. In 35% of surviving animals, brain infarctions were observed in one and exceptionally two areas of the sensorimotor cortex, thalamus, hippocampus or cerebellum. The evolutionary sequence of the histopathological changes seems to date the induction of the infarcts to the early period of carotid occlusion. In conclusion, reduction of cerebral blood flow causes, in a high percentage of animals, various degrees of acute brain damage after an apparent symptom-free interval.

Animals↗
PubMed1991

[Use of 5 French catheters in percutaneous femoral coronaro-ventriculography (500 consecutive procedures with 5 French catheters)].

To verify the advantages and the systematic use of 5 French catheters in femoral percutaneous coronaroventriculography, 500 consecutive unselected patients with confirmed or suspected coronary artery disease underwent this procedure. In one case only (0.2%) we had recourse to 7 French catheters on account of the inability to enter the left coronary ostium. There were no major local complications. General complications were represented by vagal reactions in 20 cases (4%) and by transient minor motor aphasia in one case (0.2%). The cardiac complications were represented by: -1 (0.2%) atrio-ventricular isorhythmic dissociation; -1 (0.2%) complete right bundle branch block; -3 (0.6%) atrial fibrillation; (all had a rapid and spontaneous regression) -1 (0.2%) ventricular fibrillation treated successfully with D.C. shock; -1 (0.2%) non fatal acute myocardial infarction (at the end of the procedure); -2 (0.4%) attacks of cardiac asthma treated successfully with medical therapy. 5 French catheters have proved to be extremely efficacious, with some technical experience, in percutaneous coronaroventriculography via femoral approach. The possible advantages could consist of a reduction in local complications, a patient's precocious mobilization and a minor traumatism on the arterial wall. The major complications are comparable with those observed using 7-8 French catheters. In the future it might be possible, in selected patients, to use 5 French catheters to perform ambulatory cardiac catheterization with reduction of both costs and hospitalization period.

Aged↗
PubMed1990

Epileptic activity following 10 minute cerebral ischemia in Mongolian gerbils: an electrophysiological study.

The effects of bilateral carotid occlusion (BCO) on electroencephalographic (EEG) activity and hippocampal structural integrity was studied in 25 Mongolian gerbils. During BCO EEG became flat in frontal cortex and hippocampus but bilateral spikes and motor signs were recorded during this period. Following release of clamping EEG gradually recovered within 36 h but interictal activity persisted disappearing on the 6th-7th day. At the end of 7 days a selective necrosis of CA1 hippocampal neurons was observed. The results indicate that 10 min cerebral ischemia induces a transient epileptic activity followed by the CA1 neuronal loss. Mechanisms underlying ischemic damage are complex and probably they involve an altered synaptic transmission.

Animals↗
PubMed1990

New experimental technique for detecting the effect of low-frequency electric fields on enzyme structure.

A new experimental approach has been developed to determine kinetic and thermodynamic parameters of the inactivation of an enzyme under labile conditions both with and without exposure to electrical currents as sources of perturbation. Studies were undertaken to investigate if low-frequency electric currents can accelerate the thermal inactivation of an enzyme through interactions with dipole moments in enzymatic molecules and through related mechanical stresses. The experiments were conducted with the enzyme acid phosphatase. The enzyme was exposed to a 50-Hz current at different densities (10 to 60 mA/cm2 rms) or to a sinusoidal or square-wave current at an average density of 3 mA/cm2 and frequencies from, respectively, 50 Hz to 20 kHz and 500 pulses per second (pps) to 50,000 pps. Positive-control experiments were performed in the presence of a stabilizer or a deactivator. The results indicate that the technique is sensitive to conformational changes that otherwise may be impossible to detect. However, exposure to electric currents under the experimental conditions described herein showed no effects of the currents.

Acid Phosphatase↗
PubMed1990

An external carotid artery shunt to prevent cerebral ischaemia during carotid surgery.

The contribution of the external carotid artery to cerebral blood flow in the presence of an internal carotid occlusion or severe stenosis is well documented. This study was undertaken in order to try and exploit the external carotid artery as a collateral pathway to avoid cerebral ischaemia during carotid surgery. The main problem is to ascertain when the external carotid artery is relevant to cerebral perfusion, and to assess if the insertion of a shunt from the common to the external carotid artery is a useful way of ensuring adequate cerebral perfusion in patients with cerebral ischaemia during carotid clamping. In order to do this, it was necessary to assay the haemodynamic role of the external carotid artery by means of a technique which monitors cerebral function in a reliable way. We tried to evaluate this possibility by an intra-operative haemodynamic study during carotid surgery in 35 patients operated on under local anaesthesia. The insertion of a shunt between the common and external carotid artery was able to reverse brain ischaemia during clamping in four of eight patients with a neurological deficit during temporary carotid occlusion. In selected cases therefore cerebral protection with an external carotid shunt might be a valuable adjunct in the performance of carotid surgery.

Aged↗
PubMed1989

Transcranial unifocal stimulation in rabbit: subcutaneous and meningeal changes.

The possible acute morphological changes induced by electrical transcranial unifocal stimulation (eTCS) in the rabbit extracerebral tissues were studied by light and scanning electron microscopy. In order to do this, a wide range of electric stimuli with respect to those employed in the clinical practice were utilized. Either surface electrodes were attached to the scalp, or needle electrodes were infixed in the subcutaneous tissue. Beneath the cathode a blood extravasation was constantly observed in the subcutaneous tissue of the scalp; the different electrode arrays produced either a large hemorrhagic lesion or a few petechiae. Beneath the anode, the damage was limited to the scalp, or reached the meninges when stimuli longer than 0.2 ms were used. Irrespective of the electrode arrays, the scalp and the dura mater displayed hemorrhagic petechiae over a limited area about 2-3 mm in extent. Moreover, the leptomeningeal membrane was microscopically disrupted over an area less than 1 mm large; therein the squamous, overlapping cells were transformed into fusiform or macrophage-like cells. Unduly intense eTCS produces evident hemorrhagic lesions in the scalp and in the dura mater, whereas it induces microscopic, reactive changes in the leptomeninx.

Animals↗
PubMed1989

Right colonic hemangioma diagnosed by scintigraphy with 99-mTc sucralfate. A case report.

99-mTc-SF gastrointestinal scintigraphy used in recent years in the assessment of site and activity for ulcerative lesions, was shown to be very important for the diagnosis of a rare case of right colonic hemangioma. A young female patient suffering for some time from functional intestinal disorders, following negative radiologic and endoscopic findings, underwent 99-mTc-SF scintigraphy, which showed massive uptake of radioactivity in the ascending and right flexure of colon. A repeated colonoscopy with biopsy allowed the histologic diagnosis of capillary hemangioma.

Adult↗
PubMed1989

Assessment of peritoneal spread of tumor by scintigraphy. A case report.

A case of peritoneal scintigraphy performed in a patient eligible for peritoneal locoregional treatment with previous positioning of an implantable device is reported. The result of scintigraphy has played a major role in the diagnosis of adhesion and thus in the subsequent therapeutic approach. Indications for peritoneal scintigraphy in the preliminary stage of locoregional treatment by completely implantable devices, are also briefly discussed.

Adenocarcinoma↗
PubMed1988

The salvage of the lower limbs: choice of the prosthetic material in femoro-distal and axillo-femoral bypass.

The choice of the prosthetic material in arterial surgery of patients with rest pain and/or impending gangrene of the lower limbs still presents several problems. The poor run-off, the small caliber of the distal vessels, the crossing of the joint areas and the length of the bypass may lead to early occlusion of the prosthesis. This experience is based on 268 femoro-distal (214 femoro-popliteal below the knee and 54 femoro-tibial) and on 121 axillo-femoral/popliteal bypasses (89 axillo-femoral, 28 axillo-bifemoral and 4 axillo-popliteal). In the 389 surgical procedures we have employed the autologous saphenous vein in 208 cases, Polytetrafluoroethylene (PTFE) straight or tapered in 66, PTFE external supported (EXS) in 33, Dacron in 12, homologous saphenous vein in 7 and PTFE EXS Thin Wall in 5. In 58 cases a composite graft (autologous saphenous vein plus synthetic prosthesis) was used. The cumulative long term (12-96 months) patency is 75.96% for autologous saphenous vein bypass, 62.12% for PTFE, 75.75% for PTFE EXS, 41.66% for Dacron, 42.85% for homologous saphenous vein and 84.48% for the composite graft. All the PTFE EXS Thin Wall grafts are still patent (12 months).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗