Metabotropic Glutamate Receptors Inhibiting Excitatory Synapses in the CA1 Area of Rat Hippocampus

In the CA1 region of hippocampal slices prepared from young adult rats, we studied the ability of several specific agonists of metabotropic glutamate receptors (mGluRs) to depress excitatory synaptic transmission at the CA3–CA1 pyramidal cell synapses. Three groups of mGluRs have been described: group 1 (mGluR1 and 5) receptors are positively coupled to phospholipase C whereas group 2 (mGluR2 and 3) and group 3 (mGluR4, 6, 7 and 8) receptors are negatively coupled to adenylate cyclase. We found that the broad-spectrum agonist (1 S ,3R)-1-aminocyclopentyl-1,3-dicarboxylate and the group 1-specific agonist ( R,S )-dihydroxyphenylglycine both reversibly inhibited evoked field excitatory postsynaptic potentials, indicating the involvement of group 1 mGluRs. ( R,S )-3,5-dihydroxyphenylglycine presumably inhibited transmission via a presynaptic mechanism, as whole-cell voltage-clamp recordings revealed that inhibition of the synaptic transmission was always accompanied with an increase in paired-pulse facilitation. Treatment with a specific blocker of mGluR1 receptors, the phenylglycine derivative ( S )-4-carboxyphenylglycine, was without effect on the (1 S ,3 R )-1-amino-cyclopentyl-1,3-dicarboxylate-induced depression of the field excitatory postsynaptic potentials, strongly suggesting that mGluR5 receptors are responsible for the (1 S ,3 R )-1-aminocyclopentyl-1,3-dicarboxylate effect. Two selective agonists of group 2 mGluRs, (2 S ,1' s ,2' s )-2-(2'-carboxycyclopropyl)glycine and 4-carboxy-3-hydroxyphenylglycine, were totally ineffective in blocking CA3-CA1-evoked synaptic transmission, excluding the involvement of mGluR2/3 subtypes at this developmental stage.     

Aneurysm of the abdominal aorta in an eighteen-month-old child

We report the case of an infected aneurysm of the abdominal aorta in a 18 month-old child, discovered by routine palpation of the abdomen during hospitalization for pneumonia. Ultrasonography and arteriography showed a 6 cm aneurysm of the abdominal aorta beginning distal to the renal arteries which occluded the right common Iliac artery. The aneurysm was treated by interposing a 6 mm Gore-Tex graft between the infrarenal aorta and the aortic bifurcation. Pathologic examination of the aneurysmal wall demonstrated a leukocytic Infiltrate and the presence of encapsulated Gram positive organisms. Arterial aneurysms are exceedingly rare in children. Their etiology is varied: infection, connective tissue disease, trauma, inflammatory arterial disease or other rare diseases such as tuberous sclerosis, neurofibromatosis, or Beçhet’s disease.     

Phenytoin prodrug 3-phosphoryloxymethyl phenytoin (ACC-9653): pharmacokinetics in patients following intravenous and intramuscular administration

A phenytoin prodrug, 3-phosphoryloxymethyl phenytoin (ACC-9653; 1), has been developed with more favorable physicochemical properties than phenytoin for parenteral administration. The purpose of this study was to evaluate the pharmacokinetic profile of 1 following iv and im administration in adult patients receiving chronic oral phenytoin monotherapy. Each patient (9 males, 1 female) received a single iv dose of undiluted 1 equivalent to their twice daily phenytoin dose (100-200 mg). An equivalent dose of im 1 was administered in the gluteus maximus muscle one week later. Serial blood samples were obtained after each dose. Phenytoin and 1 concentrations were measured using HPLC. Compartmental analysis using weighted nonlinear least squares, and noncompartmental pharmacokinetic analysis were performed on each patient's concentration-time data. Data following iv 1 in eight of ten patients were best described using a two-compartment model. Mean pharmacokinetic parameter estimates for iv 1 in these patients were central volume of distribution (Vdc) of 0.040 +/- 0.0084 L/kg and plasma disappearance half-life (t1/2 alpha) of 8.0 +/- 2.9 min ("conversion" t1/2). Overall mean clearance (CL) was 0.24 +/- 0.080 L/kg/h in the 10 patients. Mean pharmacokinetic parameter estimates for im 1 were a rate constant (ka) of 2.47 +/- 1.41 h-1 and an absolute bioavailability (F) of 100.5 +/- 20.3%. Mean observed tmax values for phenytoin were 0.57 +/- 0.26 and 1.46 +/- 0.76 h following iv and im 1, respectively. Model-independent estimates of clearance agreed well with the compartmental analyses. Steady-state predose phenytoin concentrations did not significantly vary from the comparable concentrations following iv 1 administration (p = 0.22).(ABSTRACT TRUNCATED AT 250 WORDS)     

Genetic polymorphism of CCR5 gene and HIV disease: The heterozygous (CCR5/Δccr5) genotype is neither essential nor sufficient for protection against disease progression

Homozygous (Δccr5/Δccr5) and heterozygous (CCR5/Δccr5) deletions in the β-chemokine receptor 5 (CCR5) gene, which encodes for the major co-receptor for macrophage-tropic HIV-1 entry, have been implicated in resistance to HIV infection and in protection against disease progression, respectively. The CCR5/Δccr5 genotype was found more frequently in long-term nonprogressors (LTNP) (31.0%) than in progressors (10.6%, p < 0.0001), in agreement with previous studies. Kaplan-Meier survival analyses showed that a slower progression of disease, i.e. higher proportion of subjects with CD4⁺ T cell counts >500/μl (p = 0.0006) and a trend toward a slower progression to AIDS (p = 0.077), was associated with the CCR5/Δccr5 genotype. However, when LTNP were analyzed separetely, no significant differences in CD4⁺ T cell counts (p = 0.12) and viremia levels (p = 0.65) were observed between the wild-type (69 % of LTNP) and the heterozygous (31.0 %) genotypes. Therefore, there are other factors which play a major role in determining the status of nonprogression in the majority of LTNP. Furthermore, there was no evidence that the CCR5/Δccr5 genotype was associated with different rates of disease progression in the group of progressors. Taken together, these results indicate that the CCR5/Δccr5 genotype is neither essential nor sufficient for protection against the progression of HIV disease.     

Human cytomegalovirus UL144 gene polymorphisms in congenital infections

The human cytomegalovirus (HCMV) UL144 gene is a tumor necrosis factor-like receptor with the potential to affect HCMV virulence. HCMV strains display genetic variability in the UL144 region, and the analysis of a potential link between UL144 gene polymorphisms and disease severity has scarcely been studied. However, a correlation between the UL144 genotype and congenital-disease outcome has been reported in one previous study, with the observation that all asymptomatic infants had a single UL144 genotype. In order to confirm or refute this finding, we determined the UL144 polymorphisms of HCMV strains recovered from the amniotic fluids of 38 infected fetuses and compared them to HCMV strains obtained from 30 viremic adult controls. The UL144 sequences were distributed among five genotypes (A, B, C, AC, and AB), as previously described. We observed similar percentages of the three major genotypes A (37%), B (33%), and C (27%) in our population. The UL144 genotype distributions were similar among the group of infected adults and the group of infected fetuses and among symptomatic and asymptomatic fetuses (P < 0.05). In our series, all five UL144 genotypes could be vertically transmitted from mothers to fetuses, and all could cause symptomatic congenital infection. We concluded that determination of UL144 polymorphisms in cases of congenital infection is not relevant, since it is unlikely to help predict the outcome of the infection.     

Superinfecting mycobacteria home to established tuberculous granulomas

A central paradox of tuberculosis immunity is that reinfection and bacterial persistence occur despite vigorous host immune responses concentrated in granulomas, which are organized structures that form in response to infection. Prevailing models attribute reinfection and persistence to bacterial avoidance of host immunity via establishment of infection outside primary granulomas. Alternatively, persistence is attributed to a gradual bacterial adaptation to evolving host immune responses. We show here that superinfecting Mycobacterium marinum traffic rapidly into preexisting granulomas, including their caseous (necrotic) centers, through specific mycobacterium-directed and host cell-mediated processes, yet adapt quickly to persist long term therein. These findings demonstrate a failure of established granulomas, concentrated foci of activated macrophages and antigen-specific immune effector cells, to eradicate newly deposited mycobacteria not previously exposed to host responses.     

Early Impairment of CD8+ T Cells Immune Response Against Epstein–Barr Virus (EBV) Antigens Associated with High Level of Circulating Mononuclear EBV DNA Load in HIV Infection

Immunodeficiency related to HIV may increase the incidence of EBV-associated lymphomas, by altering EBV-specific immune control and consequently favoring EBV reactivation. The aim of the present study was to assess the relationship between the decrease of EBV-specific cellular immunity and the increase of EBV reactivation in a prospective cohort of 72 unselected HIV-infected individuals. EBV-specific immunity was evaluated by a highly sensitive IFN-gamma ELISPOT assay using 22 peptides mimicking latent and lytic antigens, and circulating mononuclear (PBMC) EBV DNA load was quantified by real-time quantitative PCR. The mean circulating cell-associated EBV DNA load was higher in HIV-infected patients (639 copies/10(6) PBMC) than in healthy controls (21, n = 14) ( P = 0.005) and was higher in patients with CD4(+) T-cell count below 350/microL than that in patients harboring higher CD4(+) T-cell count (1112 vs. 389, P = 0.003). The mean intensity of EBV-specific cellular responses was lower in HIV-infected patients than in controls ( P = 0.001), even in patients with CD4(+) T-cell count above 350/-microL ( P = 0.007). The number of EBV peptides recognized was lower in HIV-infected patients than in controls (frequency: 0.44 vs. 0.67; P = 0.02), indicating reduced polyclonality in HIV-infected patients. The polyclonality was 1.5-fold lower in HIV-infected patients with CD4(+) T-cell count below 350/-microL ( P =0.007). For EBV load >1000 copies/10(6) PBMC, the levels of cell-associated EBV DNA and those of EBV-specific cellular immunity, either in intensity or in polyclonality, or both, were inversely correlated. These findings demonstrate early impairment of the EBV-specific cellular immune control with progressive increase of EBV reactivation in the course of HIV infection. These observations likely provide a basis for appreciating the risk to develop non-Hodgkin's lymphomas in HIV-infected individuals.     

Chronic ethanol exposure differentially regulates NOS1 mRNA levels depending on rat brain area

In vitro experiments were performed on brainstem – spinal cord preparations from mouse neonates to compare the noradrenergic regulations of the respiratory network in the control C3H/HeJ strain and the transgenic Tg8 strain which has been created from the C3H/HeJ strain by deletion of the gene encoding monoamine oxidase A (MAOA), the main enzyme for serotonin degradation. In both control and MAOA-deficient strains, we show: (i) that the pontine A5 area exerts a potent inhibitory modulation on the respiratory rhythm generator; (ii) that noradrenaline application induces a tonic phrenic activity; and (iii) that noradrenaline increases the respiratory rhythm. The latter effect is however delayed and weak in the Tg8 strain. Therefore, MAOA-deficiency has only slightly altered the noradrenergic regulations of the respiratory network.     

Antifungal coating by biofunctionalized polyelectrolyte multilayered films

The surface of medical devices is a common site of bacterial and fungal adhesion, first step to the constitution of a resistant biofilm leading frequently to chronic infections. In order to prevent such complications, several physical and chemical modifications of the device surface have been proposed. Here, we experiment a new type of topical antifungal coating using the layer-by-layer technique. The nanometric multilayer film obtained by this technique is functionalized by the insertion of a chromogranin A-derived antifungal peptide (CGA 47-66, chromofungin). We show that the embedded peptide keeps its antifungal activity by interacting with the fungal membrane and penetrating into the cell. In vitro studies demonstrate that such an antifungal coating is able to inhibit the growth of yeast Candida albicans by 65% and completely stop the proliferation of filamentous fungus Neurospora crassa. The cytotoxicity of such a coating was also assessed by growing human gingival fibroblasts at its surface. Finally, the antifungal coating of poly(methylmethacrylate), a widely used material for biomedical devices, is successfully tested in an in vivo oral candidiasis rat model. Taken together, these results assessed the functionalized multilayer films containing a new potent antifungal non-toxic peptide, as a novel and promising technique for local antifungal protection.