Long term effects of lipopolysaccharide on satellite glial cells in mouse dorsal root ganglia.

Lipopolysaccharide (LPS) has been used extensively to study neuroinflammation, but usually its effects were examined acutely (24h<). We have shown previously that a single intraperitoneal LPS injection activated satellite glial cells (SGCs) in mouse dorsal root ganglia (DRG) and altered several functional parameters in these cells for at least one week. Here we asked whether the LPS effects would persist for 1 month. We injected mice with a single LPS dose and tested pain behavior, assessed SGCs activation in DRG using glial fibrillary acidic protein (GFAP) immunostaining, and injected a fluorescent dye intracellularly to study intercellular coupling. Electron microscopy was used to quantitate changes in gap junctions. We found that at 30 days post-LPS the threshold to mechanical stimulation was lower than in controls. GFAP expression, as well as the magnitude of dye coupling among SGCs were greater than in controls. Electron microscopy analysis supported these results, showing a greater number of gap junctions and an abnormal growth of SGC processes. These changes were significant, but less prominent than at 7 days post-LPS. We conclude that a single LPS injection exerts long-term behavioral and cellular changes. The results are consistent with the idea that SGC activation contributes to hyperalgesia.

Purinergic signaling mediated by P2X7 receptors controls myelination in sciatic nerves.

Adenosine-5'-triphosphate, the physiological ligand of P2X receptors, is an important factor in peripheral nerve development. P2X7 receptor is expressed in Schwann cells (SCs), but the specific effects of P2X7 purinergic signaling on peripheral nerve development, myelination, and function are largely unknown. In this study, sciatic nerves from P2X7 knockout mice were analyzed for altered expression of myelin-associated proteins and for alterations in nerve morphology. Immunohistochemical analyses revealed that, in the wild-type peripheral nerves, the P2X7 receptor was localized mainly in myelinating SCs, with only a few immunopositive nonmyelinating SCs. Complete absence of P2X7 receptor protein was confirmed in the sciatic nerves of the knockout mice by Western blot and immunohistochemistry. Western blot analysis revealed that expression levels of the myelin proteins protein zero and myelin-associated glycoprotein are reduced in P2X7 knockout nerves. In accordance with the molecular results, transmission electron microscopy analyses revealed that P2X7 knockout nerves possess significantly more unmyelinated axons, contained in a higher number of Remak bundles. The myelinating/nonmyelinating SC ratio was also decreased in knockout mice, and we found a significantly increased number of irregular fibers compared with control nerves. Nevertheless, the myelin thickness in the knockout was unaltered, suggesting a stronger role for P2X7 in determining SC maturation than in myelin formation. In conclusion, we present morphological and molecular evidence of the importance of P2X7 signaling in peripheral nerve maturation and in determining SC commitment to a myelinating phenotype.

Chiral/ring closed vs. achiral/open chain triazine-based organogelators: induction and amplification of supramolecular chirality in organic gels.

The purpose of this study is to compare the gelling behavior of two molecules: a chiral compound and its achiral counterpart. The chiral partner is characterized by a rigid, chiral pyrrolidine nucleus, while the achiral one contains a flexible diethanolamine moiety. The chiral compound is an already known good organogelator, but also the achiral compound shows remarkable gelling properties. Very interestingly, a small fraction of the chiral compound induces chirality and strong CD effects in its aggregates with the achiral one. The observed chirality amplification corresponds to a peculiar sergeant-and-soldier effect. Molecular modelling and CD calculations suggested a model for the supramolecular assembly of hetero-aggregates that fits the experimental data.

Ectopic mandibular third molar: report of two cases by intraoral and extraoral access.

Ectopic third molar displacement is a rare event in the population. The etiology of this infrequent condition has not been completely clarified. Optimal management is still unclear. In symptomatic patients surgical removal, after a careful preoperative planning, is the recommended treatment. Several surgical approaches, both extraoral and intraoral, have been described, depending on the ectopic molar position. This paper reports two cases of ectopic third molar, one located in the coronoid process and the other one in the lower edge of the mandibular body. Both teeth were removed successfully by an intraoral and extraoral approach respectively.

Trans-nasal endoscopic and intra-oral combined approach for odontogenic cysts.

Maxillary cysts are a common finding in maxillofacial surgery, dentistry and otolaryngology. Treatment is surgical; a traditional approach includes Caldwell-Luc and other intra-oral approaches. In this article, we analyse the outcomes of 9 patients operated on using a combined intra-oral and trans-nasal approach to the aforementioned disease. Although the number of patients is small, the good results of this study suggest that the combined approach might be a reliable treatment option.

Thia-bridged triarylamine heterohelicene radical cations as redox-driven molecular switches.

The first example of one-electron oxidation of thia-bridged triarylamine heterohelicenes to the corresponding exceptionally stable radical cations, fully characterized, as hexafluoroantimonate salts, by means of UV-Vis, EPR, ENDOR, density functional theory calculations and X-ray analyses, is reported. Chemical and electrochemical reversible redox processes are solidly demonstrated.

Nifedipine gastrointestinal therapeutic system in stable angina pectoris. Results of a multicenter open-label crossover comparison with standard nifedipine.

To compare the clinical efficacy and dose equivalency of standard nifedipine versus a new gastrointestinal therapeutic system (GITS) formulation of nifedipine, 98 patients with chronic stable angina pectoris participated in a 14-week, multicenter, open-label, crossover trial. All patients were administered nifedipine capsules for one month prior to study entry and continued receiving other antianginal, non-calcium blocker medications. Ninety-one patients (93 percent), 80 men and 11 women, mean age 62 +/- 1 years, completed the trial, which included two weeks receiving standard nifedipine followed by 12 weeks receiving nifedipine GITS starting at a dosage equal to the 24-hour total dose of nifedipine capsules and titrated upward as necessary. However, throughout the trial, mean nifedipine dosage was similar on nifedipine GITS compared with standard nifedipine. Angina frequency was significantly less with nifedipine GITS at Weeks 6, 10, and 14 (0.8 episodes/week) compared with baseline with standard nifedipine (1.3 episodes/week, p less than 0.05). Likewise, nitroglycerin consumption was also less at Weeks 6, 10, and 14, but only significantly less at Week 6 (nifedipine 1.2/week versus nifedipine GITS at six weeks, 0.7/week; p less than 0.05). Resting hemodynamic parameters, including systolic and diastolic blood pressure and heart rate, were not significantly different with standard nifedipine versus nifedipine GITS during the 12-week study. Total incidences of side effects were similar for both treatments (standard nifedipine, 16; nifedipine GITS, 17). However, incidence of vasodilator side effects (flushing, dizziness, and light-headedness) was significantly less frequent with nifedipine GITS (standard nifedipine, 12; nifedipine GITS, six; p less than 0.05). Thus, results from this open-label, crossover trial suggest that nifedipine GITS dosing is similar to multidose standard nifedipine with equivalent 24-hour efficacy for nifedipine GITS.

Dissimilar atrial rhythms diagnosed by echocardiography.

A 27-year-old woman with ectopic atrial rhythm and apparent atrioventricular dissociation was found to have A waves on the mitral echocardiogram that bore no relation to the P wave on the surface electrocardiogram. The ECG did not reflect the presence of dissimilar atrial rhythms, and their presence became apparent only during the echocardiographic studies. The mechanism of this phenomenon and its clinical implications are discussed.

Spasm of a saphenous vein bypass graft. A possible mechanism for occlusion of the venous graft.

The phenomenon of spasm in a venous graft was documented by angiographic study of the graft. This phenomenon has not been reported previously, and, therefore, its frequency of occurrence is unknown. Spasm of a venous graft may prove to play a significant role in the early development of myocardial infarction, closure of the graft, or recurrence of angina after initially successful surgery for aortocoronary bypass when venous grafts remain patent.

Permethrin-impregnated curtains in malaria control.

The impact of permethrin-impregnated curtains on the incidence of malaria episodes, parasitaemia and splenomegaly was assessed during a 22 month period in 2 groups of children aged 0.5-6 years. One group lived in houses where permethrin-impregnated curtains had been installed, the other group lived in houses without curtains. A significant reduction of incidence of malaria episodes, mean parasite density, parasite prevalence and splenomegaly was consistently observed in the intervention group towards the end of the period of moderate transmission, whereas no clear-cut impact could be demonstrated during the high transmission period. The influence of malaria pressure and community utilization on the protective efficiency of curtains is discussed. Because of their acceptability and the ease of reimpregnation, curtains proved to be a suitable technique for integration into primary health care.

Ultrastructural localization of actin in the cell body of rat spinal ganglion neurons.

We used phalloidin staining and immunocytochemistry at the light and electron microscope level to determine the localization of actin in the cell bodies of rat spinal ganglion neurons. The results show that actin is mostly concentrated along the periphery of the neuronal perikaryon, including the perikaryal projections. This localization places actin in a strategic position to be influenced by incoming signals and to produce mechanical tensions able to shape the perikaryal surface.

The perikaryal projections of rabbit spinal ganglion neurons. A comparison of thin section reconstructions and scanning microscopy views.

Shape, length and width of the perikaryal projections of spinal ganglion neurons from adult rabbits fixed in situ by perfusion have been evaluated by means of serial section electron microscopy. The results thus obtained have been compared with those obtained by enzymatic removal of ganglionic connective tissue and satellite cells followed by direct observation of the true neuronal surface under the scanning electron microscope. The comparison has shown that the perikaryal projections exhibit a similar shape and similar size with both techniques.

The perikaryal surface of spinal ganglion neurons: differences between domains in contact with satellite cells and in contact with the extracellular matrix.

The perikaryal surface of spinal ganglion neurons undergoes dynamic changes throughout life. In particular, numerous slender projections develop and retract continuously from this surface. We showed previously that the outgrowth of these projections, while an intrinsic property of spinal ganglion neurons, is also influenced by the surrounding microenvironment. Since the latter consists of satellite cells and the extracellular matrix, we sought to determine the relative contributions of each of these components to the outgrowth of perikaryal projections. To this end, we took advantage of a little known characteristic of the satellite cell sheaths: in the rabbit, these sheaths can exhibit gaps that leave the nerve cell body surface directly exposed to the extracellular matrix. We compared the surface domains covered by satellite cells with those in direct contact with the extracellular matrix. We found that the perikaryal projections are abundant in the former domains but are absent in the latter. We also found that the perineuronal extracellular matrix of rabbit spinal ganglia contains laminin and fibronectin, two glycoproteins that have been reported to promote the growth of axonal processes from sensory ganglion neurons. Laminin and fibronectin were also present at the level of the gaps in the satellite cell sheath. These results: (1) provide additional evidence that environmental factors influence the outgrowth of perikaryal projections from spinal ganglion neurons; (2) suggest that satellite cells permit the outgrowth of these projections; (3) suggest that in the spinal ganglia of adult rabbits the perineuronal extracellular matrix is not in itself able to promote the outgrowth of these projections. This study provides a further example of the influence that supporting neuroglial cells have on sensory ganglion neurons.

The percentage of nerve cell bodies arranged in clusters decreases with age in the spinal ganglia of adult rabbits.

In the spinal ganglia of the rabbit the nerve cell bodies, which in early developmental stages are mutually in contact, come to be completely isolated from each other by a satellite cell sheath and by a connective envelope before birth. The present study demonstrates that in the early postnatal months some nerve cell bodies are still arranged in clusters, and that the percentage of these decreases progressively throughout adult life. This decrease probably arises because in some of the ganglion neurons the process of envelopment of the perikaryon by an individual sheath begins later, or takes place more slowly, than in the majority of cases. Therefore, the relationship between neurons and between neurons and satellite cells may change in certain clusters of nerve cell bodies under normal circumstances during adult life.

An electron microscope study of quantitative relationships between axon and Schwann cell sheath in myelinated fibres of peripheral nerves.

The quantitative relationships between the cross-sectional area of the Schwann cell sheath (myelin included) and that of its related axon were studied by electron microscopy in the nerve fibres of the spinal roots of lizard (Lacerta muralis). In both ventral and dorsal roots the cross-sectional area of the Schwann cell sheath (myelin included) was found to be directly proportional to that of its related axon (correlation coefficients between 0.88 and 0.92). The ratio between the cross-sectional area of the Schwann cell sheath (myelin included) and that of its related axon tends to diminish as the cross-sectional area of the latter increases. Thus, under normal conditions, in myelinated fibres of the spinal roots of the lizard a quantitative balance exists between the nerve tissue and its associated glial tissue. This result agrees with those previously obtained in the spinal ganglia of the lizard, gecko, cat and rabbit. Some of the mechanisms probably involved in the control of the quantitative balance between nerve tissue and its associated glial tissue in peripheral nerves are presented and discussed.

Comment on "Efficient stress relaxation in molecular dynamics simulations of semiflexible n-alkanes".

Contrary to the findings of Mülders, Toxvaerd, and Kneller [Phys. Rev. E 58, 6766 (1998)] (MTK), we are unable to discern any difference in the behavior of long chain alkanes simulated by molecular dynamics at constant pressure using either atomic or molecular scaling schemes. This result confirms our previous study [M. Marchi and P. Procacci, J. Chem. Phys. 109, 5194 (1998)] on hydrated proteins published at the same time as the MTK's paper. This Comment indicates that errors in the calculation of the pressure tensor might be responsible for at least a part of the MTKs results.

Italian Development Cooperation: the commitment for the struggle against malaria in Africa.

The Italian Development Cooperation (DGCS) support the health reform process in Developing Countries, with the aim to provide populations in greatest need with access to decentralized health services. DGCS acts in close coordination with the donor community, United Nations' system and the World Bank, in agreement with sector-wide approach (SWAP) for health sector development. Since malaria control in endemic countries is a relevant component of the health system, DGCS is actively involved in the struggle against malaria in sub-Saharan Africa, supporting control activities and research capability strengthening. The following African countries are presently receiving bilateral support for antimalaria activities: Burkina Faso, Centre de Lutte contre le Paludisme in Ouagadougou; Ethiopia, community-based malaria control in Tigray; Eritrea, malaria control at national level in the framework of the Public Health and Rehabilitation Programme for Eritrea (PHARPE) initiative; Madagascar, malaria surveillance at national level; Tanzania, feasibility study for the support to the national malaria control programme. Support is provided by technical/financial assistance involving Italian academic and research institutions. On the multilateral channel, DGCS has provided regular contribution for WHO's work in malaria control and participates to the WHO Roll Back Malaria initiative. A new commitment to malaria is the trilateral joint scientific endeavour USA-Italy-Burkina Faso for the development and field testing of a candidate vaccine suitable for African populations.

[Utilization of permethrin-impregnated curtains by the inhabitants of a rural community in Burkina Faso]. / Utilisation de rideaux impregnés de perméthrine par les habitants d'une communauté rurale du Burkina Faso.

The degree of utilisation of permethrin-impregnated curtains was assessed in a rural community near Ouagadougou, Burkina Faso. Results showed that in the first half of the night, until 11-11.30 p.m., curtains were only partially used by the community. Indeed by this time around 50% of houses had doors well protected by curtains and, over 35% of the community, children and adults, were staying outside. A very marked pattern of this behavior was found, wrong utilisation of curtains being higher in the warm season and lower in the cold season. On the one hand, this situation decreased the potential action of curtains as a barrier to avoid mosquito-man contact and, on the other hand, facilitated the exposure of community to the risk of outdoor infection. These findings may explain the variable level of efficacy showed by curtains in the prevention of malaria morbidity, which seems to be higher in the period between January and February, the winter season in Burkina Faso. The possible application of impregnated curtains as a community-based vector control method is discussed.

On the influence of the perineuronal microenvironment on the outgrowth of perikaryal projections of spinal ganglion neurons.

While the outgrowth of the slender projections from the perikaryon of spinal ganglion neurons is an intrinsic property of these neurons, it is also influenced by the surrounding microenvironment. To obtain evidence concerning whether the outgrowth of these projections is influenced by one or both components of the perineuronal microenvironment (satellite cells plus extracellular matrix) we have taken advantage of a rare arrangement of these neurons. In the spinal ganglia of adult animals nerve cell bodies are occasionally arranged in pairs, the two nerve cell bodies of the pair being separated by a satellite cell sheet lacking a basal lamina, while along the remaining portions of their surfaces they are enveloped by a satellite cell sheath, in turn surrounded by a basal lamina and connective tissue. By studying these paired nerve cells we have been able to compare, in the same nerve cell body, the extent of the perikaryal projections in surface domains associated only with satellite cells and in surface domains associated with both satellite cells and extracellular matrix. In spinal ganglia of the rat and lizard we have found that the overall development of the perikaryal projections does not differ significantly in either of these surface domains. This finding suggests that neuron-satellite cell interactions rather than factors in the extracellular matrix play a role in promoting the outgrowth of perikaryal projections from spinal ganglion neurons.