EAAT expression by macrophages and microglia: still more questions than answers

Glutamate is the main excitatory amino acid, but its presence in the extracellular milieu has deleterious consequences. It may induce excitotoxicity and also compete with cystine for the use of the cystine–glutamate exchanger, blocking glutathione neosynthesis and inducing an oxidative stress-induced cell death. Both mechanisms are critical in the brain where up to 20% of total body oxygen consumption occurs. In normal conditions, the astrocytes ensure that extracellular concentration of glutamate is kept in the micromolar range, thanks to their coexpression of high-affinity glutamate transporters (EAATs) and glutamine synthetase (GS). Their protective function is nevertheless sensitive to situations such as oxidative stress or inflammatory processes. On the other hand, macrophages and microglia do not express EAATs and GS in physiological conditions and are the principal effector cells of brain inflammation. Since the late 1990s, a number of studies have now shown that both microglia and macrophages display inducible EAAT and GS expression, but the precise significance of this still remains poorly understood. Brain macrophages and microglia are sister cells but yet display differences. Both are highly sensitive to their microenvironment and can perform a variety of functions that may oppose each other. However, in the very particular environment of the healthy brain, they are maintained in a repressed state. The aim of this review is to present the current state of knowledge on brain macrophages and microglial cells activation, in order to help clarify their role in the regulation of glutamate under pathological conditions as well as its outcome.     

A simple innovative spectrofluorometric method for the determination of alendronate in bulk and in pharmaceutical tablets

Sodium alendronate is the first in a pharmacological class known as bisphosphonates, used for treatment of various bone diseases. Assay of bisphosphonates by a spectroscopic technique is very challenging due to the fact that they lack chromophores and none of them are fluorescent. In this work, a simple method is presented for determination of alendronate in bulk and in pharmaceutical tablets using spectrofluorometry by exploiting the ability of alendronate to displace salicylate from the iron(III)–salicylate chelate, forming a non‐fluorescent colorless iron(III)–alendronate complex. The liberated salicylate is fluorescent and is equivalent to the mount of alendronate added. The response was linear over the concentration range 20–90 μM and the proposed method was validated according to the guidelines of the International Conference on Harmonization. The correlation coefficient was found to be 0.995 and the limit of detection was 7.5 μM. The method was successfully applied for determination of alendronate in the commercially available Osteonate® tablets. The average percent recovery ± percent relative standard deviation was found to be 102.118 ± 2.033 which is congruent with the label claim of the dosage form. The results were also compared to a reported method using t‐test and F‐test at 95% confidence level; no significant differences were observed. The presented method is simple, fast, easy, cost‐effective and suitable for routine pharmaceutical analysis.     

Activation of transposable elements and insertional polymorphism in Opuntia offspring as assessed by inter-retrotransposon amplified polymorphism markers

Activation of retrotransposon is a pivotal factor in the genesis of genetic polymorphism. Retrotransposon-based molecular markers are excellent tools for detecting genetic diversity and genomic changes associated with their activity. The objective of this study was to use IRAP markers to detect integration events of retrotransposon in Opuntia, and to compare IRAP and ISSR polymorphisms. To achieve these aims, five IRAP and five ISSR markers were analyzed on three varieties and their progenies. All IRAP primers showed an increase in the percentage of polymorphism, number of total bands, and polymorphic bands in the seedlings compared to their mother plants; that is, the offspring showed 13, 24 and 27 more bands than the mother plants from Tobarito, Montesa and Copena varieties, respectively. Conversely, sexual reproduction did not proportionally affect the variation in the number of ISSR bands, and neither did polymorphisms between mother plants and their offspring. Cluster and multivariate analyses based on IRAP and ISSR data revealed a clear separation between varieties, and there was no overlapping between seedlings of different varieties. The activation of retrotransposons in seedlings of opuntia with variable frequencies was evidenced. The presence of insertion and active retrotransposons may help to undertake studies on genetic diversity and evolution of Opuntia.     

The possible structural changes in the adrenal gland cortex after induction of hepatic ischemia–reperfusion injury in male albino rats: Light and electron microscopic study

The adrenal gland is an important endocrine gland in the body that secrets the adrenal hormones. One of the important clinical issues is the hepatic ischemia–reperfusion (IR) injury. Liver IR injury results in many distant organs dysfunctions such as lung, kidney, intestine, pancreas, and myocardium. The aim of the present study was to investigate the possible remote effects of hepatic IR on the structure of the adrenal cortex. Twenty healthy males, Sprague–Dawley albino rats aged 6–8 weeks were randomly divided into two groups (10 rats each): the sham control group (SC-group) and the ischemia–reperfusion group (IR-group). Sera were estimated for the following: aspartate transaminase (AST), alanine transaminase (ALT), lactic dehydrogenase (LDH), and corticosterone levels. Also oxidative markers such as malondialdehyde (MDA) and tumor necrosis factor-α (TNF-α), and the antioxidative enzyme, catalase were measured. Adrenal glands were processed for light and transmission electron microscopic study. The results showed a significant increase in serum liver enzymes (AST, ALT, and LDH), corticosterone, MDA, and TNF-α levels and a significant decrease in serum levels of catalase in IR-group compared with SC-group. Adrenal cortical tissue of IR-group showed the loss of normal appearance. Some cells of zona glomerulosa and most of the zona fasciculata cells appeared swollen and degenerated with highly vacuolated cytoplasm. Other cells were shrunken with deeply acidophilic cytoplasm and pyknotic nuclei. Degenerated mitochondria with disrupted cristae, lipid droplets were confluent and dilated smooth endoplasmic reticulum were seen. Few zona reticularis cells had the dark nucleus and cytoplasmic vacuolations. In the different zones, blood capillaries were markedly congested and some inflammatory cells infiltrations were observed. Liver IR affected the structure of the adrenal cortex.     

Efficacy of intra-lesional glucantime in the treatment of zoonotic cutaneous leishmaniasis in basic health care conditions

A randomized placebo-controlled trial treating cutaneous lesions due to Leishmania major with intralesionnel glucantime, was conducted in El Guettar between december 1994 and June 1995, in order to assess efficacy of this therapy under field conditions. It included 109 patients: 52 were administrated glucantime and 57 received local treatment (eosin 5% and alcohol 95%). Prognostic factors were similar in both groups. Results did not reveal a significant difference between glucantime and eosin regarding the rapidity of the healing of lesions. However, scars seem to be of better quality among the glucantime group. Bacterial super infection was noticed among 57.6% of humid lesions sampled among 33 patients. Isolated strains included group A streptococcus (22%), staphylococcus aureus (16.7%) or an association of both agents (61.1%). Resistance profile indicated that streptococcus and staphylococcus respond well to macrolids compared to other antibiotic groups.     

Are there health risks for travel among Tunisians? What type of medical care should be assured?

The present work aims to assess the importance of the international travels of Tunisians, their destinations, the risks they face as well as the means to reduce them. Therefore, data related to the period from 1989 to 1998, were collected from official organisms involved in this area. Results revealed an increase of the number of Tunisians travelling outside the country of 23% between 1989 and 1998, with a mean progress of 5.7% per year since 1993. Main destinations were Maghrebin countries (65.7%), Europe (30%) and Middle East (4%). The number of persons leaving to high risk destinations remains difficult to assess and shows the importance of implementing a surveillance system to insure an adequate medical follow-up of this category of travellers. The structures actually involved in the health management of Tunisian travellers have a weak recruitment which demonstrates the importance to strengthen the sensitization of general practitioners to this subject and the promotion of the immunization ward of "Institut Pasteur" to a national centre of travelling medicine.     

Cone Beam Computed Tomography Assessment of the Maxillary Incisive Canal and Foramen: Considerations of Anatomical Variations When Placing Immediate Implants

IntroductionThe maxillary incisive canal connects the roof of the oral cavity with the floor of nasal cavity and has the incisive and nasal foramina respectively at its two opposite ends. Its close proximity with the anterior incisors affects one’s ability to place immediate implants in ideal position.ObjectiveTo avoid causing complication, variations in their dimensions were studied.ResultsThe mean labiopalatal and mesiodistal measurements of the incisive foramen were 2.80mm and 3.49 mm respectively, while the labiopalatal width of the nasal foramen was 6.06mm. The incisive canal was 16.33mm long and 3.85 mm wide. The anterior maxillary bone has an average thickness of 7.63 mm. The dimensions of the incisive foramen and incisive canal, and anterior maxillary bone thickness demonstrated gender differences with males showing greater values. The anterior maxillary bone thickness was affected by age but this difference was not observed in canal dimensions. The majority of subjects have a funnel shape-like incisive canal with the broader opening located at its superior. They seem to have a longer slanted-curve canal with one channel at its middle portion and a narrower incisive foramen opening than those reported elsewhere.ConclusionsThis study found that gender is an important factor that affected the characteristics of the IC and the amount of bone anterior to it. Male generally had bigger IC and thicker anterior bone. In addition, the anterior maxillary bone thickness was affected by aging, where it becomes thinner with increased age even though the subjects were fully dentate.     

Essential oil composition of Hypericum triquetrifolium Turra. aerial parts

The essential oil obtained by hydrodistillation from the aerial parts of Tunisian endemic Hypericum triquetrifolium Turra (Clusiaceae) was analyzed using GC and GC-MS. One hundred and nine compounds consisting of 92.2% of total detected constituents were identified. Sesquiterpene hydrocarbons were the main constituents (59.37%), Alpha-humulene, cis-calamenene, delta-cadinene, bicyclogermacrene, eremophilene, betacaryophyllene and (E)-gamma-bisabolene were found as the main ones. Alpha-pinene (10.33%) was detected as the main monoterpene hydrocarbons (12.19%). The oxygenated sesquiterpenes constituted (9.33%); caryophyllene oxide (1.38%) was reported as the main constituent of this fraction. The oxygenated monoterpenes were weakly represented (4.62%) and consisted of constituents in low percentages (<1%).     

A tethered bilayer assembled on top of immobilized calmodulin to mimic cellular compartmentalization

Background

Biomimetic membrane models tethered on solid supports are important tools for membrane protein biochemistry and biotechnology. The supported membrane systems described up to now are composed of a lipid bilayer tethered or not to a surface separating two compartments: a ”trans” side, one to a few nanometer thick, located between the supporting surface and the membrane; and a “cis” side, above the synthetic membrane, exposed to the bulk medium. We describe here a novel biomimetic design composed of a tethered bilayer membrane that is assembled over a surface derivatized with a specific intracellular protein marker. This multilayered biomimetic assembly exhibits the fundamental characteristics of an authentic biological membrane in creating a continuous yet fluid phospholipidic barrier between two distinct compartments: a “cis” side corresponding to the extracellular milieu and a “trans” side marked by a key cytosolic signaling protein, calmodulin.

Methodology/Principal Findings

We established and validated the experimental conditions to construct a multilayered structure consisting in a planar tethered bilayer assembled over a surface derivatized with calmodulin. We demonstrated the following: (i) the grafted calmodulin molecules (in trans side) were fully functional in binding and activating a calmodulin-dependent enzyme, the adenylate cyclase from Bordetella pertussis; and (ii) the assembled bilayer formed a continuous, protein-impermeable boundary that fully separated the underlying calmodulin (trans side) from the above medium (cis side).

Conclusions

The simplicity and robustness of the tethered bilayer structure described here should facilitate the elaboration of biomimetic membrane models incorporating membrane embedded proteins and key cytoplasmic constituents. Such biomimetic structures will also be an attractive tool to study translocation across biological membranes of proteins or other macromolecules.