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Biomedical subjects

S Geuna

Publications and source records attributed to S Geuna.

At least 19 recordsLinked to original sources
PubMed2007

Origin and history of end-to-side neurorrhaphy.

This historical note offers a perspective concerning the origin of the employment of end-to-side (termino-lateral) anastomosis for nerve repair and summarizes the works that have been published on this surgical technique through the first part of the 20th Century. While the origin of end-to-side neurorrhaphy is usually dated to the beginning of the 20th Century, some works referring to this technique were published earlier, the first of which dates as far back as 1873. A number of interesting clinical and experimental studies have been carried out on end-to-side nerve anastomosis during the first years of the twentieth century. However, this literature is not easily detectable through current online scientific databases. In this paper we will give an overview of these early works. This history contributes interesting information to the debate surrounding this surgical concept and adds perspective to the use of a technique that has attracted a great deal of attention over the last 15 years.

Anastomosis, Surgical↗
PubMed2007

Comparison of fresh and predegenerated muscle-vein-combined guides for the repair of rat median nerve.

Over the last 10 years, we have investigated a particular type of bioengineered nerve guide, the muscle-vein-combined tube, which is made by filling a vein with skeletal muscle. In our previous studies we have always used fresh skeletal muscle to fill vein conduits. In the present study we compared the use of fresh and predegenerated (freeze-thawed) skeletal muscle for muscle-vein-combined nerve guides. In this study, a 10-mm-long rat median nerve defect was repaired using either type of nerve guide. The samples were analyzed 5 and 30 days after surgery by light and electron microscopy. In addition, reverse transcription polymerase chain reaction (RT-PCR) was carried out to investigate the expression of mRNAs coding for glial markers, as well as glial growth factor (NRG1) and its receptors (erbB2 and erbB3). Results showed differences between the two types of nerve guides at postoperative day 5; however, no difference was detected at day 30 suggesting that both types of tissue-engineered conduit are effective for repairing peripheral nerve defects in this experimental model.

Animals↗
PubMed2006

Lack of topographic specificity in nerve fiber regeneration of rat forelimb mixed nerves.

Multiple nerve repair by means of a Y-shaped nerve guide represents a good model for studying the specificity of peripheral nerve fiber regeneration. Here we have used it for investigating the specificity of axonal regeneration in mixed nerves of the rat forelimb model. The left median and ulnar nerves, in adult female rats, were transected and repaired with a 14-mm Y-shaped conduit. The proximal end of the Y-shaped conduit was sutured to the proximal stump of either the median nerve or the ulnar nerve. Ten months after surgery, rats were tested for functional recovery of each median and ulnar nerve. Quantitative morphology of regenerated myelinated nerve fibers was then carried out by the two-dimensional disector technique. Results showed that partial recovery of both median and ulnar nerve motor function was regained in all experimental groups. Performance in the grasping test was significantly lower when the ulnar nerve was used as the proximal stump. Ulnar test assessment showed no significant difference between the two Y-shaped repair groups. The number of regenerated nerve fibers was significantly higher in the median nerve irrespectively of the donor nerve, maintaining the same proportion of myelinated fibers between the two nerves (about 60% median and 40% ulnar). On the other hand, nerve fiber size and myelin thickness were significantly larger in both distal nerves when the median nerve was used as the proximal donor nerve stump. G-ratio and myelin thickness/axon diameter ratio returned to normal values in all experimental groups. These results demonstrate that combined Y-shaped-tubulization repair of median and ulnar nerves permits the functional recovery of both nerves, independently from the proximal donor nerve employed, and that tissue, and not topographic, specificity guides nerve fiber regeneration in major forelimb mixed nerves of rats.

Animals↗
PubMed2006

Drug use and kidney donation: what are high-risk behaviors today?

BACKGROUND: "Social risk behaviors" are usually considered as contraindications for organ donation. The organ shortage, however, necessitates expansion of the donor pool. Reconsideration of the policy toward substance abusers may be important. Opinions of the overall population may be of use to define this cultural-sensitive issue. METHODS: A semistructured questionnaire on organ donation, including opinions on drug use (cannabis and cocaine), was administered to various groups of the general public and caregivers: high school students (liceo classico: 59 students, median age 18 years; istituto tecnico: 108, age 17); first- and fourth-year medical school (77, age 19; 46, age 22); continuing medical education (44, age 32); third-year nursing school (31, age 23); "senior citizen university" (51, age 63). RESULTS: Cannabis use was mainly accepted for kidney donation (48.6% yes, 26.6% no, 29.8% uncertain/blank), but cocaine use was not (22.1% yes, 44.2% no, 33.7% uncertain/blank). In the univariate analysis, opinions differed according to age, sex, and belonging to the health care teams upon multivariate analysis being a member of the health care team was the strongest predictor of responses (P<.01). CONCLUSION: It is difficult to define social risk behaviors. Since opinions are important for organ donation, further studies and discussion are needed to periodically analyze our policies.

Adolescent↗
PubMed2006

Is male homosexuality still a cultural taboo for kidney donation?

BACKGROUND: Among the so-called social risk behaviors, male homosexuality is probably one of the most interesting and difficult taboos. Because of changing attitudes of the general population toward irregular sexual behaviors, often considered as markers of unhealthy life styles, there is a need to reconsider at least the most important one-homosexuality. METHODS: A semistructured questionnaire included opinions on homosexuality with respect to kidney donation: Would you consider a male homosexual as a kidney donor? If you were on dialysis, would you accept a kidney from a homosexual donor? This instrument was administered to various groups of the general public and caregivers: high school students (Liceo Classico: 59 students, median age 18 years; Istituto Tecnico: n=108, median age 17); first and fourth year of medical school (n=77, age 19; 46, age 22); continuing medical education (n=44, age 32); third year of nursing school (n=31, age 23); "senior citizen university" (n=51, age 63). RESULTS: Male homosexuality was well accepted for kidney donation (71.6% yes, 9.6% no, 18.8% uncertain/blank). However, the opinions were different among the groups with male students of a technical institute showing discrimination against male homosexuals. In the univariate analysis, opinions differed according to age, gender, and belonging to the health care team. In the multivariate analysis, the latter was the strongest predictor (P<.01). The specific threats for the health are not well known, even among the caregiver population. CONCLUSION: It is difficult to define the role of homosexuality among the so-called social risk behaviors. Negative attitudes existed in some subsets of the population.

Adolescent↗
PubMed2005

Intracellular Ca2+ concentration in the N1E-115 neuronal cell line and its use for peripheric nerve regeneration.

Entubulation repair of peripheral nerve injuries has a lengthy history. Several experimental and clinical studies have explored the effectiveness of many biodegradable and non-degradable tubes with or without addition of molecules and cells. The main objective of the present study was to develop an economical and also an easy way for culturing a neural cell line which is capable of growing, differentiating and producing locally nerve growth factors, that are otherwise extremely expensive, inside 90 PLA/10 PLG nerve guides. For this purpose the authors have chosen the N1E-115 cell line, a clone of cells derived from mouse neuroblastoma C-1300 with the perspective of using this differentiated cellular system to cover the inside of 90 PLA/10 PLG nerve guides placed to bridge a nerve gap of 10 mm in the rat sciatic nerve experimental model. The N1E-115 cells proliferate in normal culture medium but undergo neuronal differentiation in response to DMSO. Upon induction of differentiation, proliferation of N1E-115 cells ceases, extensive neurite outgrowth is observed and the membranes become highly excitable. While it is known that Ca2+ serves as an important intracellular signal for cellular various processes, such as growth and differentiation, be toxic to cells and be involved in the triggering of events leading to excitotoxic cell death in neurons. The [Ca2+]i in non-differentiated N1E-115 cells and after distinct periods of differentiation, have been determined by the epifluorescence technique using the Fura-2-AM probe. The results of this quantitative assessment, revealed that N1E-115 cells which undergo neuronal differentiation for 48 hours in the presence of 1.5% DMSO are best qualified to be used to cover the interior of the nerve guides since the [Ca2+]i was not found to be elevated indicating thus that the onset the cell death processes was not occurred.

Animals↗
PubMed2005

Determination of the intracellular Ca2+ concentration in the N1E-115 neuronal cell line in perspective of its use for peripheric nerve regeneration.

Entubulation repair of peripheral nerve injuries has a lengthy history. Several experimental and clinical studies have explored the effectiveness of many biodegradable and non-degradable tubes with or without addition of molecules and cells. The main objective of the present study was to develop an economical and also an easy way for culturing a neural cell line which was capable of growing, differentiating and producing locally nerve growth factors that are otherwise extremely expensive, inside 90 PLA/10 PLG nerve guides. For this purpose the authors have chosen the N1E-115 cell line, a clone of cells derived from mouse neuroblastoma C-1300 with the perspective of using this differentiated cellular system to cover the inside of 90 PLA/10 PLG nerve guides placed to bridge a gap in the rat sciatic nerve experimental model. The N1E-115 cells proliferate in normal culture medium but undergo neuronal differentiation in response to DMSO. Upon induction of differentiation, proliferation of N1E-115 cells ceases, extensive neurite outgrowth is observed and the membranes become highly excitable. While it is known that Ca2+ serves as an important intracellular signal for various cellular processes, such as growth and differentiation. It is also known that can be toxic to cells and is involved in the triggering of events leading to excitotoxic cell death in neurons. The [Ca2+]i in non-differentiated N1E-115 cells and after distinct periods of differentiation, have been determined by the epifluorescence technique using the Fura-2-AM probe. The results of this quantitative assessment revealed that N1E-115 cells which undergo neuronal differentiation for 48 hours in the presence of 1.5% DMSO are best qualified to be used to cover the interior of the nerve guides since the [Ca2+]i was not found to be elevated indicating thus that the onset the cell death processes was not occurred.

Animals↗
PubMed2004

Low-power laser biostimulation enhances nerve repair after end-to-side neurorrhaphy: a double-blind randomized study in the rat median nerve model.

Previous studies have shown that low-power laser biostimulation (lasertherapy) promotes posttraumatic nerve regeneration. The objective of the present study was to investigate the effects of postoperative lasertherapy on nerve regeneration after end-to-side neurorrhaphy, an innovative technique for peripheral nerve repair. After complete transection, the left median nerve was repaired by end-to-side neurorrhaphy on the ulnar "donor" nerve. The animals were then divided into four groups: one placebo group, and three laser-treated groups that received lasertherapy three times a week for 3 weeks starting from postoperative day 1. Three different types of laser emission were used: continuous (808 nm), pulsed (905 nm), and a combination of the two. Functional testing was carried out every 2 weeks after surgery by means of the grasping test. At the time of withdrawal 16 weeks postoperatively, muscle mass recovery was assessed by weighing the muscles innervated by the median nerve. Finally, the repaired nerves were withdrawn, embedded in resin and analyzed by light and electron microscopy. Results showed that laser biostimulation induces: (1) a statistically significant faster recovery of the lesioned function; (2) a statistically significant faster recovery of muscle mass; (3) a statistically significant faster myelination of the regenerated nerve fibers. From comparison of the three different types of laser emissions, it turned out that the best functional outcome was obtained by means of pulsed-continuous-combined laser biostimulation. Taken together, the results of the present study confirm previous experimental data on the effectiveness of lasertherapy for the promotion of peripheral nerve regeneration and suggest that early postoperative lasertherapy should be considered as a very promising physiotherapeutic tool for rehabilitation after end-to-side neurorrhaphy.

Animals↗
PubMed2004

Descriptive and topographic anatomy of the accessory infraorbital foramen. Clinical implications in maxillary surgery.

AIM: Study of frequency and position of accessory infraorbital foramen in a large craniological sample. METHODS: A sample of 1 064 skulls from the craniological collection of the Department of Anatomy, Pharmacology and Forensic Medicine of the University of Turin (Italy) was investigated. RESULTS: Accessory infraorbital foramen was found in 4.7% of the skulls (5.4% in male and 4.26% in female skulls) with a higher frequency on the left side, both in male and in female skulls. CONCLUSION: These results increase our knowledge of the interindividual anatomic variability of the infraorbital region and can be of help for the maxillo-facial surgeon, especially in trunk block of the infraorbital nerve.

Adolescent↗
PubMed2003

HuC/D confocal imaging points to olfactory migratory cells as the first cell population that expresses a post-mitotic neuronal phenotype in the chick embryo.

In the present study, the expression of the HuC/D RNA-binding proteins, a marker of neurons that have left the mitotic cycle, in cells migrating from the olfactory neuroepithelium toward the telencephalon in the chick embryo was investigated by means of immunofluorescence and confocal laser microscopy. Results showed that this migratory cell population is early and massively labeled by the a-HuC/D antibody starting from the first olfactory pit stage. At this developmental stage, olfactory migratory cells appeared to be the only neuronal population that expressed the HuC/D antigens in the whole embryo. In following developmental stages, the great majority of migratory cells, the number of which increased progressively, continued to be heavily immunopositive for the a-HuC/D antibody while immunopositivity to this antibody begins to be detected in other regions of the nervous system. HuC/D immunopositivity persisted until stage 30 HH (about 6.5 days), the later developmental stage investigated in this study, when colocalization with GnRH was detected. Negativity to the anti-proliferating cell nuclear antigen (anti-PCNA) immunostaining, a marker of S-phase, showed that migratory olfactory cells have left the mitotic cycle. Altogether, these results suggest that we have identified the first population of post-mitotic neurons in the developing nervous system of the chick embryo.

Animals↗
PubMed2003

Schwann-cell proliferation in muscle-vein combined conduits for bridging rat sciatic nerve defects.

Among the various grafting procedures that have been studied as alternatives to traditional fresh nerve autografts for the repair of severed peripheral nerves, muscle-vein-combined graft conduits have recently been devised and successfully employed. In the present study, the early presence, origin, and proliferation activity of Schwann cells (SCs) along this particular type of biological graft conduit have been investigated, using antibodies directed against glial fibrillar acid protein (GFAP), a protein that is specifically expressed in glial cells, and proliferating cell nuclear antigen (PCNA), a protein that is expressed by cells during DNA synthesis. Results showed that the muscle-vein-combined graft was progressively invaded by a number of GFAP-immunopositive SCs, many of which were also found to be immunopositive for PCNA, thus demonstrating that their proliferation continues to occur inside the graft. Among the molecules that could be involved in the stimulation of Schwann-cell proliferation is neuregulin-1 (NRG-1) that mediates its effects by binding to the ErbB receptor tyrosine kinase family. In the present study, the authors report on the RT-PCR analysis for NRG-1 and ErbB3 mRNAs, showing an overall increase in the content of these transcripts inside the muscle-vein-combined graft. These results suggest that the muscle-vein-combined graft conduit constitutes an environment favorable to potentiate Schwann-cell proliferation during the early regeneration phases.

Animals↗
PubMed2002

The use of brainstorming for teaching human anatomy.

Interactive teaching techniques have been used mainly in clinical teaching, with little attention given to their use in basic science teaching. With the aim of partially filling this gap, this study outlines an interactive approach to teaching anatomy based on the use of "brainstorming." The results of the students' critique of the teaching techniques are also included. Seventy-five students from the first-year nursing curriculum were tested by a structured questionnaire after three brainstorming sessions. The overall response to these sessions was very positive, indicating that students perceived this interactive technique as both interesting and useful. Furthermore, this approach may provide a useful strategy when learning the clinical courses of the upcoming academic years.

Anatomy↗
PubMed2001

Unscheduled DNA synthesis in rat adult myenteric neurons: an immunohistochemical study.

Unscheduled DNA synthesis refers to DNA synthesis not followed by cell division. Previous studies have suggested that this phenomenon may occur in neurons from peripheral myenteric ganglia in conditions of functional hyperstimulation. In order to verify these observations, we have carried on an immunohistochemical study on myenteric neurons from the hypertrophic intestinal loops upstream from a partial obstruction (an experimental condition that induces a relevant increase of the neuronal workload) after labelling with two different markers: the proliferating cell nuclear antigen (PCNA), that is specifically expressed in cell nuclei during the S-phase, and the protein gene product 9.5 (PGP 9.5), a specific marker of nerve cells. While no myenteric neuron immunopositive for the anti-PCNA antibody was found in the control intestine, in the hypertrophic myenteric ganglia some neurons were positive for PCNA. These results provide an unequivocal evidence on the existence of unscheduled DNA synthesis in myenteric neurons from the hypertrophic intestine.

Animals↗
PubMed2001

Adult stem cells and neurogenesis: historical roots and state of the art.

Over the last few years, an impressive number of papers have addressed the stem cell issue. However, as often occurs when a scientific subject undergoes a period of fast growth, some confusion is generated. To help reduce the existing uncertainty, this paper focuses on the concept of adult stem cells in relation to the classification of cell populations on the basis their proliferative behavior. Particular attention is dedicated to adult neural stem cells, an issue that has recently seen the most amazing advances. Finally, the concept of adult stem cells is differentiated from that of developmental stem cells in relation to the employment of stem cells for transplantation therapies.

Adult↗
PubMed2001

Confocal imaging of Schwann-cell migration along muscle-vein combined grafts used to bridge nerve defects in the rat.

Schwann cells guide axonal regrowth during peripheral nerve repair. In a case of a nerve lesion with substance loss, a graft conduit is necessary to enable axons to reach the distal nerve stump. If a non-nervous autograft is used, the question arises as to the presence and origin of Schwann cells along the grafted tube. We addressed this issue using a tubulization technique based on the use of an autologous vein filled with fresh skeletal muscle for the repair of sciatic nerve defects in the rat. We showed that both ends of the graft were early and progressively colonized by a number of glial fibrillar acid protein-immunopositive and S-100 immunonegative cells, an immunocytochemical pattern typical of immature Schwann cells. These cells, which were located in the interstice between grafted skeletal muscle fibers, are mainly organized into long chains oriented along the main axis of the graft and progressively colonize all the graft. Schwann cells coming from the distal nerve end are suitable for being responsible for guiding regeneration of nerve fibers along the graft toward the correct periphery (tissue specificity).

Animals↗
PubMed2001

Methodological issues in size estimation of myelinated nerve fibers in peripheral nerves.

Size estimation of myelinated nerve fibers in peripheral nerves is a very common task in neuromorphology and different dedicated morpho-quantitative procedures have been devised and used to date. Unfortunately, many reports on experimental nerve studies lack comprehensive information on the procedures that have been designed and applied for myelinated fiber size estimation. This paper addresses the issue in the light of the recent advances in quantitative morphology that have recognized the concept of unbiased estimates as the key methodological issue to be addressed in morpho-quantitative studies. The potential foundations of bias at various study levels are analysed together with indications on how to cope with them. In addition, the issue of the precision of size estimates is addressed and the various geometrical parameters that can be selected for myelinated nerve fiber size assessment are outlined. Taken together, information provided in this paper is expected to help investigators conduct an appropriate preliminary study design phase, the key step for setting up the most adequate morpho-quantitative procedure for any given research goal.

Animals↗