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Biomedical subjects

F Gentili

Publications and source records attributed to F Gentili.

47 records · Page 3Linked to original sources
PubMed1981

Quantitative assessment of muscular hypertonia resulting from cortical lesions in primates.

The effects of various cerebral cortical lesions on motor function and in particular on muscle tone have been studied quantitatively in the squirrel monkey (Saimiri sciureus) in an attempt to define the cause of muscular hypertonia and to develop a reliable model for human cerebral spasticity. Unilateral ablation of the primary motor area (MI), either alone or together with the supplementary motor area (MII), produced a contralateral hemiparesis especially marked for fine motor tasks, but did not cause hypertonia. Bilateral ablation of the supplementary motor area alone produced no impairment of motor function or change in muscle tone. Bilateral lesions of the primary motor area, either alone or together with the supplementary motor area, caused a disabling quandriparesis with striking hypertonia affecting chiefly the upper limb flexors and lower limb extensors. Quantitative electromyography revealed augmented stretch responses proportional to the rate of muscle lengthening. This velocity-dependent exaggerated stretch reflex, with a predominantly dynamic component reflecting hyperactivity of the Ia spindle afferents, is similar to that seen in human hemiplegic spasticity. Out results indicate that decorticate hypertonia depends upon the bilateral interruption of fiber tracts originating in motor cortex and distributed both ipsilaterally and contralaterally. Bilateral decortication in the primate seems to be a suitable laboratory model for the objective evaluation of measures proposed for the relief of spasticity in humans.

Animals↗
PubMed1980

Clinical and experimental aspects of injection injuries of peripheral nerves.

Injury to peripheral nerves complicating deep intramuscular injections of antibiotic and other agents is well recognized and can result in significant permanent neurological deficit. The purpose of this paper is to review the subject of nerve injection injuries, and report on a series of recent experimental studies carried out in this laboratory designed to improve our understanding of the pathophysiology of this condition and help provide a rational basis for its treatment. A wide variety of chemotherapeutic, prophylactic, and local anaesthetic agents in common use were injected into the sciatic nerve of the adult Wistar rat. Both intrafascicular and extrafascicular injections were examined. Results revealed that the site of injection was the most crucial factor in determining the degree of nerve fiber injury. Following intrafascicular injection, the degree of injury varied significantly, depending upon the specific agent injected. The most severe injuries were associated with wide-spread axonal and myelin degeneration. Pathological alterations in the nerve were evident as early as 30 minutes following injection injury. Regeneration was a constant finding in nerve damage by injection of the various agents. The mechanism of injury appeared to be a direct toxic effect of the injected compound on neural tissue, with an associated break down of the blood-nerve barrier.

Anesthetics, Local↗
PubMed1980

Early changes following injection injury of peripheral nerves.

Using light and electron microscopy and a fluorescent tracer technique, the authors have studied various aspects of injection injuries to nerves in an attempt to elucidate the pathophysiology of this condition and to help establish a rational basis for treatment. In 72 animals 144 nerve injections were carried out, using five drugs in current use and commonly administered by intramuscular injection. The nerves were examined at varying times (10 minutes to 10 weeks) following injection. Pathological alterations in the nerve were evident as early as 30 minutes after injection. The mechanism of injury appears to be a direct neurotoxic effect on the nerve fibre-both axon and Schwann cell-with a breakdown in the blood-nerve barrier.

Animals↗
PubMed1979

Peripheral nerve injection injury: an experimental study.

In an attempt to answer questions regarding nerve injection injuries, we injected 11 agents in current use and commonly administered by intramuscular injection into the sciatic nerves of adult Wistar rats. Equal volumes of normal saline were used as control. We harvested the sciatic nerves at various times after injection and examined them by both light and electron microscopy. We performed myelinated nerve fiber counts and constructed histograms. Any impairment of motor function was also noted. We gave injections to 79 animals a total of 158 times; 116 injections were directly into the nerve fascicle (intrafascicular) and 42 were into the epineural tissue (extrafascicular). The results revealed considerable variation in the degree of nerve fiber injury according to the agent injected. Minimal damage resulted from the injection of iron-dextran, meperidine, and cephalothin, and maximal nerve injury followed the injection of penicillin, diazepam, and chlorpromazine. The site of injection was crucial. Intrafascicular injection was invariably associated with severe nerve injury, but, with few exceptions, extrafascicular injection resulted in minimal damage. The quantity of drug injected was also important in determining the degree of injury. Large, heavily myelinated fibers were more susceptible to injection injury than smaller, thinly myelinated nerve fibers. The effect of the injected drug seemed to be related to injury of the nerve fiber unit--both the axon and the Schwann cell with its myelin sheath. Regeneration in damaged nerves was a constant finding; even the most severely injured nerves, with total axonal degeneration, underwent subsequent regeneration.

Animals↗
PubMed1975

Decorticate spasticity: a re-examination using quantitative assessment in the primate.

Decorticate spasticity in the squirrel monkey was chosen as a convenient laboratory model of spasticity capable of quantitative assessment upon which to evaluate various currently popular clinical spasmolytic measures. The effects of a wide variety of cortical lesions were studied involving primary and supplementary motor, premotor and parietal cortex unilaterally and bilaterally, measuring muscle tone with the evoked integrated E.M.G. technique. Measurable spasticity resulted only if primary motor cortex was ablated bilaterally usually but not always preferentially involving biceps brachii and quadriceps. Resulting postures were variable offering no justification for the term "decorticate posture". The integrated evoked E.M.G. was proportional to rate of stretch and chiefly phasic in type as in hemiplegic man. Stereotactic dentatectomy resulted in profound ipsilateral reduction in this spasticity, but was without effect in intercollicular or anemic decerebrate cats. The mechanism of the spasticity and of the cerebellar effects are discussed.

Animals↗
PubMedDate not supplied

Tumors of the skull base: outcome and survival analysis of 77 cases.

We reviewed our experience with combined approaches to lesions that transcend the bones of the skull base. Seventy-seven skull base procedures were performed on 73 patients during a 10-year period from 1982 to 1992. There were 34 patients (44%) with region lesions (anterior), seven patients (9%) with region II lesions (anterior-lateral), 25 patients (32%) with region III lesions (lateral-posterior), and 11 patients (14%) with lesions that invaded more than one anatomic site. The histopathology in this series was quite variable, with 22 patients (29%) having squamous cell carcinoma and eight patients (10%) having basal cell carcinoma. Forty-one patients had surgery by an anterior approach and 38 patients had lateral approaches, with 18 undergoing an infratemporal approach and 29 undergoing temporal bone resections. Overall, 44% of the patients had a postoperative complication. Survival of this heterogeneous group of patients is 79% at 2 years and 71% at 4 years, with those patients with region II disease having a statistically significant poorer prognosis with no survivors at 4 years.

Adolescent↗
PubMedDate not supplied

Predictive factors of outcome after liver transplantation in patients with cirrhosis and hepatocellular carcinoma.

Studies to define the optimal upper limits of tumor size and number as predictors of outcome after orthotopic liver transplantation (OLT) have yielded conflicting results. We analyzed 72 patients with cirrhosis and hepatocellular carcinoma (HCC) who underwent OLT over a 12-year period in a single center. Predictive factors for survival and tumor recurrence, according to the Milan criteria, were also examined. Our cohort included 60 men and 12 women of mean age 54 +/- 8 years and mean follow-up of 40 +/- 39 months. Origin of cirrhosis was postviral in 70% and Child class B or C in two thirds of patients. HCC was multifocal in 61%; about one fifth of patients had micro- or macrovascular involvement or positive nodes upon histologic examination. The cumulative size of the lesions was <3 cm in 17 patients; >3 to < or =5 cm in 28 patients; >5 to < or =8 cm in 14 patients; and >8 cm in 13 patients. According to the number and size of tumor nodules, 49 patients met the Milan criteria. During follow-up 25 patients died, 13 due to tumor recurrence. The 1- and 2-year survivals were 90% and 85% for patients who met the Milan criteria versus 57% and 51% for patients exceeding those limits (P = .006). A cumulative tumor size >8 cm was predictive of survival and tumor recurrence upon multivariate analysis. The adoption of Milan criteria for selection of cirrhotic patients has improved survival and reduced the rate of tumor recurrence. The evaluation of cumulative tumor size might further improve patient selection.

Carcinoma, Hepatocellular↗
PubMedDate not supplied

Management of pregnant women with cerebrospinal fluid shunts.

As more women with cerebrospinal fluid shunts reach child-bearing age, neurosurgeons, obstetricians and other health care providers will increasingly be called upon to care for them once they become pregnant. A review of the literature reveals that these patients may develop symptoms of shunt malfunction as uterine size increases. In most cases, symptoms can be managed conservatively during pregnancy and usually resolve following delivery. The presence of a CSF shunt per se, is not a contraindication to pregnancy and eventual fetal and maternal outcome has been excellent in the majority of cases. Labor and delivery should be allowed to progress naturally and interventions limited to those indicated for obstetrical reasons alone. Peripartum prophylactic antibiotics may be indicated and special care ought to be exercised if epidural analgesia or cesarian section is deemed necessary. Genetic investigations and counseling may be indicated in selected patients.

Adolescent↗