Biomedical subjects

G Fontanesi

Publications and source records attributed to G Fontanesi.

At least 73 records · Page 4Linked to original sources

PubMedDate not supplied

Nerve growth factor (NGF) uptake and transport following injection in the developing rat visual cortex.

Recent investigations have shown that cortical nerve growth factor (NGF) infusions during the critical period inhibit ocular-dominance plasticity in the binocular portion of the rat visual cortex. The mechanisms underlying the effects of NGF on visual cortical plasticity are still unclear. To investigate whether during normal development intracortical and/or extracortical cells possess uptake/transport mechanisms for the neurotrophin, we injected 125I-NGF into the occipital cortex of rats at different postnatal ages. Within the cortex, only a few labelled cells were observed. These cells were confined to the vicinity of the injection site and their number depended on the animal's age at the time of injection. Labelled cells were absent at postnatal day (PD) 10 but could be detected between PD 14 and PD 18. They then decreased in number over the following period and were not detected in adult animals. Outside the cortex, neurons of the lateral geniculate nucleus (LGN) were not observed to take up and retrogradely transport NGF at any age after birth. In contrast, retrogradely labelled neurons were found in the basal forebrain. Labelled cells were first observed here at PD 14 and then increased in number until reaching the adult pattern. Our results show that intrinsic and extrinsic neurons are labelled following intracortical injections of iodinated NGF. In both neuronal populations, the uptake and transport of NGF is present over a period corresponding to the critical period for visual cortical plasticity. These findings suggest that NGF may play a role, both intra and extracortically, in plasticity phenomena.

Aging↗

PubMedDate not supplied

Cysteamine-induced depletion of somatostatinergic systems alters potentials evoked from the rat visual cortex.

This study was performed in order to establish whether selective depletion of somatostatin (SS) in the rat primary visual cortex obtained by cysteamine (CSH) administration results in changes of visual evoked potentials (VEPs). VEPs in response to a contrast reversal (0.5 Hz) of an optimal sinusoidal grating (0.1 cycle/deg, contrast 90%, mean luminance 15 cd/m2) were recorded from different layers of the binocular portion of the primary visual cortex of anesthetized rats with saline injection as well as before and after CSH treatment (90 mg/kg, s.c.). VEPs of CSH treated rats, as compared to those obtained either in saline-injected animals or before drug administration, are reduced in amplitude at intermediate cortical layers whereas they are increased at deeper layers. VEP changes depend on CSH treatment and not on the extended anesthesia since no alterations in the VEP profile can be observed in saline-injected animals maintained in the same experimental condition. Forty-eight hours following CSH treatment, the VEP profile is comparable to that of saline-injected animals. Immunocytochemical analysis of the visual cortex of rats recorded 7 h after CSH treatment shows a 20-30% reduction in the number of SS-containing cortical cells. The highest reduction can be observed in cortical layer 5 although a significant decrease is also found in layers 2-3. In contrast, the pattern of SS immunoreactivity of the visual cortex of rats recorded 48 h after CSH administration is similar to that obtained in control conditions. These results indicate that a selective toxin for somatostatinergic systems induces a transient decrease of SS-containing cell number in selected cortical layers. Accordingly, CSH can serve as a useful pharmacological tool for the study of somatostatinergic function in the rat visual cortex since changes in VEPs can be related to a reduction of somatostatinergic neurons associated to CSH treatment. In particular, the present results suggest that one of the possible actions of somatostatinergic neurons in the rat visual cortex is to modulate the excitatory-inhibitory balance.

Animals↗

PubMedDate not supplied

Postnatal development of functional properties of visual cortical cells in rats with excitotoxic lesions of basal forebrain cholinergic neurons.

In the rat, visual cortical cells develop their functional properties during a period termed as critical period, which is included between eye opening, i.e. postnatal day (PD) 15, and PD40. The present investigation was aimed at studying the influence of cortical cholinergic afferents from the basal forebrain (BF) on the development of functional properties of visual cortical neurons. At PD15, rats were unilaterally deprived of the cholinergic input to the visual cortex by stereotaxic injections of quisqualic acid in BF cholinergic nuclei projecting to the visual cortex. Cortical cell functional properties, such as ocular dominance, orientation selectivity, receptive-field size, and cell responsiveness were then assessed by extracellular recordings in the visual cortex ipsilateral to the lesioned BF both during the critical period (PD30) and after its end (PD45). After the recording session, the rats were sacrificed and the extent of both cholinergic lesion in BF and cholinergic depletion in the visual cortex was determined. Our results show that lesion of BF cholinergic nuclei transiently alters the ocular dominance of visual cortical cells while it does not affect the other functional properties tested. In particular, in lesioned animals recorded during the critical period, a higher percentage of visual cortical cells was driven by the contralateral eye with respect to normal animals. After the end of the critical period, the ocular dominance distribution of animals with cholinergic deafferentation was not significantly different from that of controls. Our results suggest the possibility that lesions of BF cholinergic neurons performed during postnatal development only transiently interfere with cortical competitive processes.

Animals↗

PubMedDate not supplied

Maturation of somatostatin immunoreactivity in the pigeon retina: morphological characterization and quantitative analysis.

In addition to a modulatory function, somatostatin (SS) is likely to exert a morphogenetic and/or trophic role in the developing nervous system. In this study, a mouse monoclonal antibody directed to SS was used to investigate the posthatching development of SS-immunoreactivity (SS-ir) in the pigeon retina to provide a basis for a better understanding of the role of this peptide in retinal maturation. In the adult, SS-ir was observed in amacrine cells located in the inner nuclear layer (INL) of the entire retina. Two cell types were recognized according to their morphology. They showed a differential density distribution. Cell type indicated as "adult 1" (AD1) was characterized by pear-shaped cell bodies with single primary processes directed to the inner plexiform layer (IPL) and was mostly present in the red field. In contrast, cell type indicated as "adult 2" (AD2) was characterized by round-shaped somata with 1-3 primary processes and was highly represented in the fovea and the dorsal periphery. Posthatching maturation of the pigeon retina was characterized by drastic changes in the pattern of SS-ir. Over the first days posthatching, SS-ir was observed in sparsely distributed somata mostly located in the ganglion cell layer (GCL). This cell type indicated as "hatch" (H) was characterized by dense granular staining and became extremely rare at 7 days. Over the same period, growing SS-positive axons displaying enlarged growth cones were found in the optic tract (TrO). These observations suggest the possibility that ganglion cells transiently expressing SS are present at early stages of posthatching development. Of the two types of SS-containing cells observed in the adult, the first to be recognized morphologically was cell type AD1 which appeared at 2 days after hatching in the INL. These cells were virtually adult-like in morphology by 7 days. In contrast, cell type AD2 was not apparent until 7 days posthatching. The density (defined as number of cells/mm2 of retinal tissue) and the total number of SS-containing cells changed during posthatching maturation. In particular, the adult number of cell type AD1 was reached at about 10 days, while the number of cell type AD2 was reached at about 3 weeks posthatching. At this stage, both cell types also displayed their mature density distribution. The present findings suggest a temporal relationship between the maturation of SS-ir and developmental events which include the onset of light-driven activity and the maturation of retinal acuity.(ABSTRACT TRUNCATED AT 400 WORDS)

Aging↗

PubMedDate not supplied

Posterior sternoclavicular inveterate dislocation.

The authors report a case of posterior inveterate sternoclavicular dislocation, which came to their observation after tangential resection of the clavicle. They discuss the surgical technique of reduction and stabilization and clinical results. CT scan was the method most-suited to evaluate dislocation of the clavicle.

Adult↗

PubMedDate not supplied

Transverse fracture of the second sacral vertebra: description of a clinical case.

The authors report a rare case of transverse fracture of the second sacral vertebra that was isolated, with neurologic deficit, and treated conservatively by reduction opposing the trauma mechanism, and immobilization in plaster. After 22 months there was good neurologic recovery, although some perineal sensory disorders persisted, as did sexual deficit. This method is believed to be a valid one as an alternative to surgery, which is difficult, and not without complications.

Accidents, Occupational↗

PubMedDate not supplied

Distal centering in locked intramedullary osteosynthesis of the femur: use of a magnet-resistant probe.

The authors present an original solution for distal screw fixation in locked nail intramedullary osteosynthesis, traditionally carried out with image intensifier. The system includes the determination of an electromagnetic field produced by a microbobbin placed in the hole and, thus, coaxial with it. The study, conducted through a probe equipped with special magnet-resistant sensors capable of picking up electromagnetic variations, is based on the same principle as a compass. In addition to being effective and simple, the method avoids exposure to ionizing radiations required for the search for holes.

Bone Nails↗

PubMedDate not supplied

Snapping hip: etiopathogenesis and surgical treatment.

Snapping hip is a polymorphous pathology the genesis of which is multifactorial, characterized by a snapping sensation which may be painful, and occurring during movement of the hip or during walking. Clinical and instrumental diagnosis for an accurate etiopathogenetic classification is essential to correct surgical treatment, that must be reserved only for cases with painful symptoms and with disorders in walking. The authors provide a classification system of the syndrome, describing four different varieties of the pathology and relative surgical treatment.

Adolescent↗

PubMedDate not supplied

Recurrent anterior shoulder dislocation: preliminary experience in 29 cases treated by the Neer method and Statak screws.

The authors describe the surgical method used and present the preliminary results obtained in 29 patients affected with recurrent anterior dislocation of the shoulder treated by Neer capsuloplasty and Statak screws. The long-term results were evaluated based on the Rowe system: the score was excellent in 18 cases, good in 2, fair in 4, and poor in 5. All of the patients resumed work activity, with no restrictions, within 4 months of the onset of functional rehabilitation. The use of Statak screws allows us to simplify surgery, while guaranteeing repair of the Bankart lesion, when present. The method reported permits correction of instability, without excessive reduction of joint movement.

Adolescent↗

PubMedDate not supplied

Lumbar nerve root compression caused by herniated intradiscal gas: description of a clinical case with recurrence.

The authors report a rare case of recurrence of lumbar nerve root compression caused by herniated intradiscal gas treated surgically with resolution of pain symptoms. They describe the possible causes of the formation of gaseous material reported in the literature. They believe that to avoid recurrence it is important to associated removal of the hernia with complete emptying of the disc and resection of the posterior longitudinal ligament.

Gases↗

PubMedDate not supplied

Antibiotic and antithromboembolic prophylaxis in prosthetic surgery of the knee.

The prevention of deep sepsis and venous thromboembolism in knee replacement surgery is of great importance for the final success of treatment. General rules of prevention must be followed when using antimicrobial drugs (environment, surgical method, patient selection). Although it does have some negative aspects (overuse, high costs, development of resistant bacteria) the administration of antibiotics is recommended, but only when it is timely, correct, and carried out for a suitable amount of time. The prevention of thromboembolism is based first on the selection of patients who risk the occurrence of angiology-related diseases, on continuous passive postoperative movement, and, finally, on intentional normovolemic hemodilution, for which the procedures used and the advantages obtained are described.

Anti-Bacterial Agents↗

PubMedDate not supplied

The locked intramedullary Grosse Kempf nail in the treatment of proximal diaphyseal fractures of the femur.

The authors studied the effectiveness of locked intramedullary nailing (Grosse-Kempf) in the treatment of proximal shaft femoral fractures. They reviewed 24 cases with an average two-year follow-up and which had obtained positive clinical radiographic results in 80% of cases as compared to 88% in a previous revision of femoral shaft fractures. The difference is due to the greater difficulty encountered in intraoperative reduction of fractures from which defects in axial (varus) and rotatory (extra) alignment arise. They discuss indications as regards locking type, weight-bearing, as well as surgical techniques, which may prevent some of the most frequent problems observed.

Adolescent↗

PubMedDate not supplied

An evaluation of some leukocytary phenotypes in subjects with evolutive primary coxarthrosis and in subjects with hip prostheses.

The authors examined 52 patients (36 females and 16 males) of whom 15 affected with evolutive primary coxarthrosis, 27 with hip prostheses for 4 to 13 years, and 10 with a prosthetic implant which was not tolerated. A method of indirect immunofluorescence with monoclonal antibodies against specific antigens of the cellular surface was used to typify the T-lymphocytic subpopulations (T-helper/inducer and T-suppressor/cytotoxic), the activated mononucleate cells (DR+), and the B-lymphocytes and monocytes. A good correlation between the imbalances in the T-lymphocytic subpopulations, an increase in the activated mononucleate cells (principally due to T-lymphocytes) and the tolerance of the implant were observed. Based on the results obtained, the authors hypothesize the possibility of using the typing of T-lymphocytes and activated mononucleate cells, together with other biohumoral parameters, as indicators of periprosthetic tissue phologosis.

Aged↗

PubMedDate not supplied