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M G Fiori

Publications and source records attributed to M G Fiori.

67 records · Page 4Linked to original sources
PubMed1986

A sexually dimorphic nucleus in the quail preoptic area.

The cytoarchitectural analysis of the preoptic-anterior hypothalamic region of the Japanese quail reveals a sexual dimorphism in the total volume of the medial preoptic nucleus (significantly larger in males than in females). Different nuclei of the region (dorsal preopticus, suprachiasmaticus) do not show any statistically significant difference. The sex-related difference is more consistent comparing the distribution of dark volume. This last is due to a larger number of cells containing high amount of Nissl's substance in male than in female. Present findings represent the first example of sexual dimorphism in the avian hypothalamus.

Animals↗
PubMed1985

Communicating hydrocephalus in rodents treated with beta,beta'-iminodipropionitrile (IDPN).

Beta,beta'-Iminodipropionitrile (IDPN), a neurotoxic compound known to induce swellings in the proximal internodes of sensory and motor axons in several parts of the central nervous system (CNS), was also found to cause hydrocephalus in rats and guinea pigs. In both species, ventricular dilatation was observed within 1 week following a single i.p. injection of IDPN. While in rats the severity of hydrocephalus correlated with dose and duration of IDPN exposure, in guinea pigs studies with high doses yielded inconclusive results, and no significant temporal correlation was noted. Parallel investigations with another neurotoxic agent, acrylamide, in rats, and with IDPN in cats failed to demonstrate any change in size and shape of the cerebrospinal fluid (CSF) pathways. No signs of spontaneously occurring hydrocephalus were found in control animals. In both rats and guinea pigs intoxicated with IDPN, macroscopic and microscopic findings were consistent with the diagnosis of communicating hydrocephalus. Treatment of hydrocephalic rats with acetazolamide (500 mg/kg) markedly attenuated ventricular distention, suggesting that an overproduction of CSF by the choroid plexus is responsible for the communicating hydrocephalus following IDPN intoxication.

Acetazolamide↗
PubMed1985

Evolution of axonal swellings in cats intoxicated with beta,beta'-iminodipropionitrile (IDPN). An electrophysiological and morphological study.

beta,beta'-Iminodipropionitrile (IDPN) causes formation of axonal swellings in the proximal internodes of spinal motor axons. The swellings enlarge and demyelinate with the progression of the neuropathy. The correlation between axonal swellings and electrophysiologic function of motoneurons was examined in cats 2 to 35 days after initial administration of IDPN. Morphologic changes in intraspinal motor axons, occasionally observed 2 days after the first injection, became progressively more evident at later times, with enlargement at the first internode in some axons and appearance of fusiform or balloon-like axonal swellings. At 7 days axonal swellings were infrequently observed and the main structural feature was a reduction in myelin thickness in affected nerve fibers. Despite scant histopathologic changes, motoneuron action potential discharge at this time was significantly altered in latency to onset of spike and rate of rise. Abnormal motoneuron firing patterns were observed at this time. As the neuropathy progressed, both the frequency of occurrence and the size of axonal swellings increased markedly but at no time was there morphologic evidence of chromatolysis. At 14 and 35 days, (after two or five IDPN injections) action potential discharge became further altered in latency to spike onset, rate of rise, initial segment conduction time and somal-dendritic threshold. The incidence of repetitive firing increased and axonal conduction block was observed in several motoneuron recordings. The electrophysiologic changes closely resemble those reported in chromatolytic motoneurons after axotomy. The axonal swellings induced by IDPN may produce an axotomy-like condition which becomes more prominent as the neuropathy progresses but without morphologic evidence of chromatolysis.

Action Potentials↗
PubMed1983

Selective atrophy of the type IIb muscle fibers in rheumatoid arthritis and progressive systemic sclerosis (scleroderma). A biopsy histochemical study.

We have examined biopsy material from the left m. vastus lateralis of eight patients suffering from rheumatoid arthritis and four patients with progressive systemic sclerosis (scleroderma). All were chosen according to the duration and the severity of disease, so that the broadest possible spectrum of signs and symptoms could be considered. Muscular specimens showed a selective and constant atrophy of the type IIB fibers, as revealed by the myofibrillar ATPase histochemical reaction (both at a pH of 9.4 and with pre-incubation at pH 4.35 and 4.63). Atrophy of the type I fibers was seen only occasionally. Neither structural abnormalities, such as 'motheaten' fibers, nor inflammatory reactions were observed. We think that (1) changes in skeletal muscles of patients with rheumatoid arthritis and progressive systemic sclerosis may be quite selective, and (2) the myopathy associated with rheumatoid arthritis can be differentiated from inflammatory myopathies, even in muscle biopsy specimens, on the basis of histoenzymologic investigations.

Adult↗
PubMed1977

Tricyclic antidepressants: a review of their toxicology.

The tricyclic antidepressants have a complex interaction with several tissues both in experimental animals and in man. Side effects exerted by these drugs may be so severe as to justify a careful management of each individual depressed patient. The clinician must be aware of these effects above all in treating overdose poisoning and suicide attempts. This paper reviews the tricyclic-induced organic and psychologic disturbances, attention being paid to the antidepressant pharmacodynamics and the importance of biogenic amines-reuptake inhibition. Further studies on the pharmacokinetics of tricyclic antidepressants are needed however to clarify the mechanisms of their side effects. In this situation, increased drug levels should be tried only after lower dosages have proved ineffective in relieving the depressive symptomatology. In any case, the greatest caution should be used in the treatment of patients with cardiovascular diseases, severe hypertension, glaucoma, or a tendency to retain urine. Nevertheless, at present no new antidepressant has been found which may offer more selective therapeutic advantages than the classical tricyclic thymoleptics (imipramine-like drugs).

Abnormalities, Drug-Induced↗
PubMedDate not supplied

Peripheral neuropathy induced by intravenous administration of vincristine sulfate in the rabbit. An ultrastructural study.

The lack of a suitable animal model for the peripheral neuropathy that often follows the systemic administration of the chemotherapeutic agent vincristine sulfate (VCR) has hampered the correlation between experimental and clinical patterns of this neuropathy. New Zealand rabbits have been recently found to develop, after iv injection of a VCR total dosage similar to that used in humans, a peripheral polyneuropathy characterized by electrophysiological changes that overlap those observed in the clinical setting. The present study was aimed at investigating the ultrastructural features of 3 different nerves (sural, peroneal, and medial gastrocnemius) in rabbits treated with 3 VCR doses that fall within the range (0.2-0.3 mg/kg i.v.) known to be efficacious chemotherapeutically and active neurotoxicologically. Regardless of the dose and the nerve under examination, histopathologic alterations appeared in the form of an overall loss of myelinated fibers, accompanied by successful attempts of regeneration and remyelination. Fibers undergoing Wallerian degeneration were characterized by an axoplasm, which was either watery-flocculent or divided in 2 or more regions as a consequence of ingrowing Schwann cell processes from the adaxonal surface. These ingrowths tended to isolate axoplasmic areas, retaining a fairly normal structure from other areas already crowded with altered organelles and cytoskeletal elements. In any event, neurofibrillary accumulations were rarely seen. These patterns are discussed with reference to those reported in the ultrastructural studies of human cases and confirm the suitability of rabbit as an animal model for VCR-induced peripheral neuropathy.

Animals↗
PubMedDate not supplied

Estrogen receptors in colorectal adenocarcinomas and in other large bowel diseases.

Seventy-two patients with tumor and ten with non-neoplastic colon disease were studied for the presence of estrogen receptors (ER) by three different methods. Only seven specimens (six primary adenocarcinomas and one recurrent cancer) had an ER concentration above 3 fm/mg of cytosolic protein, with no sex, age and tumor stage correlation. Our results suggest that the large bowel does not contain a cytosolic receptor for estradiol.

Adenocarcinoma↗
PubMedDate not supplied

Neuropathy target esterase is not reduced in neural tissues of diabetic rats.

Marked (greater than 70%) reduction of the neuropathy target enzyme (NTE) shortly after exposure to organophosphorus compounds heralds the onset of delayed neuropathic damage in animals and humans. One previous study reported that lymphocyte NTE from diabetic patients was depressed by greater than 70%; such a reduction was considered to be a biological marker of diabetic polyneuropathy. To ascertain whether NTE from target tissues might be involved in diabetic neuropathy, we measured NTE activity in the brain, spinal cord and peripheral nerves of streptozotocin-diabetic rats. No reduction in NTE activity was detected in these neural specimens. Therefore, it is concluded that NTE is not involved in diabetic nerve damage and that the meaning of low NTE activity in peripheral lymphocytes of diabetic patients remains unclear.

Animals↗
PubMedDate not supplied

Peripheral nerve regeneration through a novel bioresorbable nerve guide.

A nerve guide made of a benzyl ester of hyaluronic acid (HYAFF11p75) was used to bridge 8 mm gaps in rat tibial nerves. Histologic observations indicated that this biomaterial provoked only a transient, modest inflammatory response, and the resorption rate was compatible with the nerve regeneration processes. Phagocytosis of the biomaterial began after neoangiogenesis and cell migration had taken place from both stumps into the nerve guide material. For comparison, the regeneration achieved was evaluated in nerve guides made of either HYAFF11p75 or Silastic, and in nerves repaired with the autograft technique. Recovery was assessed in vivo 90 days after implantation by measuring the nerve compound action potential (CAP) and conduction velocity (NCV) of the regenerated tibial nerve. The results demonstrate that the nerve guide tubes made of HYAFF11p75 were able to support and direct axonal growth, thereby suggesting a possible use for such biomaterial in the management of short nerve gaps in human pathology.

Animals↗
PubMedDate not supplied

Effect of intracarotid injection of iopamidol on local cerebral glucose utilization in rat brain.

We assessed, by means of the [14C]-2-deoxy-D-glucose autoradiography method, the effect of intracarotid injection of a nonionic, low-osmolar contrast medium (iopamidol) on local cerebral glucose utilization in the rat brain. Contrast medium was injected at 20 degrees C and at 37 degrees C, and the relative changes in local cerebral glucose utilization were measured. At 20 degrees C the viscosity of the contrast agent was about twice that of the same solution at 37 degrees C, and resulted in a statistically significant increase in local cerebral glucose utilization in the hemisphere ipsilateral to the side of intracarotid infusion. Saline control studies showed that the metabolic change was not related to either the solution temperature or the osmolality. These findings suggest that increased viscosity of a contrast medium may contribute to its neurotoxic effects during cerebral angiography, hence emphasizing the importance of preheating contrast material to avoid adverse reactions.

Animals↗
PubMedDate not supplied

Muscle fiber splitting, capillary internalization, and target-like fiber formation in familial amyloidotic polyneuropathy.

A case of familial amyloidotic polyneuropathy (FAP) is reported in which peripheral nerve and skeletal muscle biopsies were obtained from the right leg to assess the severity of the relatively late-onset but rapid-evolving neuropathy. The present paper deals with some remarkable features found in the muscular biopsy, taken from peroneus brevis and extensor digitorum longus muscles. Several fibers contained amyloid masses characterized by Congo red positivity and birefringence on polarized light microscopy: histoenzymologic staining revealed that these fibers were always type 2B and appeared grossly hypertrophied. The presence of amyloid inside the muscle fibers was possibly dependent on the internalization of capillaries leading to direct deposition of amyloid fibrils into the sarcoplasm. Fiber vascularization occurred independently of fiber splitting, which appeared to be frequent in both muscles and was characterized by unusual segmental changes in the histochemical properties of the daughter fibers with respect to those of the parent fiber. Target/targetoid and degenerating areas were also observed in a large number of type 2 fibers, usually in close relationship with segmental splitting phenomena. These findings were interpreted as possible secondary myopathic changes accompanying chronic denervation-reinnervation episodes in the course of FAP.

Amyloid Neuropathies↗