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Biomedical subjects

G Germanà

Publications and source records attributed to G Germanà.

At least 55 records · Page 3Linked to original sources
PubMed1988

Anticonvulsant effects of avermectin in DBA/2 mice and rat.

The anticonvulsant activity of avermectin B (AVM) was studied after systemic administration in DBA/2 mice (seizures induced by sound) and rats (seizures induced by pentylenetetrazol, cephazolin and maximal electroshock test). Protection against sound-induced seizures was given after intraperitoneal administration of AVM (30 and 50 mg/kg). Cephazolin-induced seizures in rats were attenuated by intraperitoneal administration of AVM (10 and 20 mg/kg). AVM increased the antipentylenetetrazol activity of diazepam. No significant protection against the tonic component in the electroshock test was observed. Behavioural effects of AVM included signs of sedation in both mice and rats. In all, these results indicate that, besides its specific anthelmintic effects, AVM possesses anticonvulsant properties, the mechanism(s) of which still remain to be elucidated.

Animals↗
PubMed1985

Development of the pigeon bursa of Fabricius. A scanning and transmission electron microscope study.

The development of the pigeon bursa of Fabricius was investigated by means of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Particularly SEM emphasized that the bursa during development progressively undergoes hypertrophia and hyperplasia of lobules constituting the plicae. Moreover modifications of surface epithelium were observed. During early days of development after hatching, epithelium showed evenly distributed microvilli which become shorter and shorter and also unevenly distributed with aging. In addition TEM allowed us to state that the bursa of Fabricius in pigeons, during development, undergoes morphological modifications among which one of the most remarkable is the gradual and continuous increasing of lymphocytes. Another one, as it was already observed in chickens (Frazier 1974), consists in the contemporaneous but independent development of cortex and medulla, even if we observed undifferentiated epithelial cells moving from medulla to cortex and a migration of lymphocytes and mesenchymal cells from cortex to medulla (Tar et al. 1958; Ackerman et al. 1964; Naukkarinen et al. 1978).

Age Factors↗
PubMed1985

Experimental modification of the growth of the bursa of Fabricius in chickens revealed by scanning and transmission electron microscopy.

The ultrastructural changes occurring in the bursa of Fabricius of 3 and 7 d old chickens after adriamycin treatment are described. Male Hubbard chickens 7 d old, were injected with a intraperitoneal injection of adriamycin (5 mg/kg/die). All chickens were killed 24 h after the last injection, and the bursa was rapidly excised and fixed immediately for scanning electron microscopy and for transmission electron microscopy. The bursa underwent atrophy and showed epithelium desquamation. After 6 d treatment the dysepithelization was evident. Consequently follicles were made up mostly with large polyedric cells.

Animals↗
PubMed1984

Stimulation of crop sac and pituitary lactotrophs after intraventricular administration of dermorphin in pigeons.

The effects of dermorphin, a new potent opioid peptide, on structural and ultrastructural changes in the crop sac and in pituitary lactotrophs were assessed in pigeons (Columba livia). A single administration of dermorphin into the third cerebral ventricle (1 microgram) and the same dose repeated for 3 consecutive days both produced maximal crop sac stimulation, as documented by the presence of milk-like material as well as by scanning and transmission electron microscopy of crop sac mucosa. In addition, marked stimulatory effects were also observed in pituitary lactotrophs, as shown by stimulation of Golgi apparatus, enlargement of rough endoplasmic reticulum, increase in mitochondria size, and the presence of lysosomes and electron-opaque granules. The stimulatory effects of dermorphin on the crop sac and lactotrophs were completely prevented by naloxone, an antagonist at opiate receptors. Since dermorphin is a natural constituent of the avian brain, it has been suggested that this peptide may represent the still-obscure hypothalamic prolactin stimulatory factor.

Animals↗
PubMed1983

Histochemical characteristics of rabbit stapedius muscle.

A histochemical analysis of rabbit stapedius muscle fibers was conducted using the myofibrillar ATPase and NADH-tetrazolium reductase techniques. Two different fiber types, type 1 and type 2b, were identified. The functional significance of the results is discussed.

Adenosine Triphosphatases↗
PubMed1979

Crop-sac response after systemic and intraventricular administration of neuroleptic drugs.

Present experiments were aimed at studying in pigeons the effects of some neuroleptic agents given systemically or into the 3rd cerebral ventricle on PRL secretion and following morphological changes of the crop-sac mucosa both by classical histological methods and scanning electron microscopy. In addition, such changes were also evaluated on the basis of a semiquantitative method using a 1-4 rating scale. 3- or 5-day systemic treatment with reserpine, haloperidol and (ł/-)-sulpiride produced an intense crop-sac response consisting of a marked epithelial hyperplasia and presence of milk-like material. Similarly, a much lower dose of haloperidol, clozapine, and the two enantiomers of sulpiride given into the 3rd cerebral ventricle for 3 consecutive days produced a marked crop-sac response. The l-sulpiride was more active in comparison to the d-enantiomer. In conclusion, present experiments show that, similarly to mammals, in pigeons neuroleptic drugs are able to stimulate prolactin secretion and suggest that these effects are mediated through an action at the hypothalamic and/or pituitary level by removing a tonic dopaminergic inhibition.

Animals↗
PubMedDate not supplied

Immunohistochemical detection of [corrected] TrkB in the enteric nervous system of the small intestine in pigeon (Columba livia).

The presence and cell localization of TrkB, the main receptor for the neurotrophins (NTs), was investigated immunohistochemically in the small intestine of adult pigeons, with special reference to the enteric nervous system (ENS). Several neuronal (neurofilament proteins and PGP 9.5) and glial cell (S100 protein) markers were studied in parallel. TrkB immunoreactivity (TrkB-IR) was found to be restricted to immunohistochemically-identified glial cells present in the enteric plexuses, and to Schwann cells forming the perivascular plexus. Also, TrkB-IR was detected in enterochromaffin cells and in unidentified dendritic cells within the gut-associated lymphoid tissue. The present results demonstrate that as for mammals, TrkB in the ENS is restricted to the glial cells. The possible function of the TrkB ligands, however, remains to be established.

Animals↗
PubMedDate not supplied

Clinical, morphometric and ultrastructural aspects in a new model of spinal cord compression.

A new model of spinal cord compression is presented. Forty-two New Zealand albino rabbits weighing between 1.2 and 1.5 kg were submitted to spinal cord compression to about half of its normal diameter by vascular Sugita's clip to different compression time (sham, 5-10-20 minutes e 1-6-12 hours) and sacrified after 72 hours. The consequent neurological dysfunction size of lesion was graded by Tarlov's scale for voluntar motility. Ultrastructural and morphometrical studies were carried out to evaluate changes in shape, perimeters, axonal and myelin areas of the lateral and the posterior tract of spinal cord. A 10 minute decrease of 50% of the transverse diameter of the spinal cord causes a defined damage. The swelling of myelin is a useful index of the importance of the damage.

Animals↗
PubMedDate not supplied

[Morphometric analysis of the sciatic nerve and its principal branches in the pigeon (Columba livia)].

The methodological approach used in this study is to characterize the number, the density and the diameter distribution of myelinated fibers (MFs) and unmyelinated fibers (UMFs) in sciatic nerve and its main branches of pigeon. The results have shown that the fiber composition is quite variable because in pigeon there are relatively MF with thin myelin sheaths and MF with thicker sheaths. Our data suggest that morphometric analysis could represent a helpful methodological approach to better characterize these systems.

Animals↗
PubMedDate not supplied

Experimental investigations on a model of cryogenic edema.

The role of mechanisms underlying formation and progression of vasogenic brain edema is investigated. On this purpose, cerebral edema was produced by cortical freezing in two different brain situations in rabbits (with or without replacement of bone flap). BBB (Blood-Brain Barrier) breakdown was evaluated by observation of Evans blue extravation, while a histopathological evaluation was carried out by light and transmission electron microscopy. Water content of brain tissue was determined by the wet/dry weight ratio method. Comparison of extension and intensity of cerebral edema between these two groups of animals shows a statistically significant difference: there was evidence of higher water content in the animals undergone replacement of bone flap. The Authors emphasize the importance of tissue pressure gradients in determining diffusion of cerebral edema.

Animals↗