Ventricular shape and relative position abnormalities in preterm neonates.

Recent neuroimaging findings have highlighted the impact of premature birth on subcortical development and morphological changes in the deep grey nuclei and ventricular system. To help characterize subcortical microstructural changes in preterm neonates, we recently implemented a multivariate tensor-based method (mTBM). This method allows to precisely measure local surface deformation of brain structures in infants. Here, we investigated ventricular abnormalities and their spatial relationships with surrounding subcortical structures in preterm neonates. We performed regional group comparisons on the surface morphometry and relative position of the lateral ventricles between 19 full-term and 17 preterm born neonates at term-equivalent age. Furthermore, a relative pose analysis was used to detect individual differences in translation, rotation, and scale of a given brain structure with respect to an average. Our mTBM results revealed broad areas of alterations on the frontal horn and body of the left ventricle, and narrower areas of differences on the temporal horn of the right ventricle. A significant shift in the rotation of the left ventricle was also found in preterm neonates. Furthermore, we located significant correlations between morphology and pose parameters of the lateral ventricles and that of the putamen and thalamus. These results show that regional abnormalities on the surface and pose of the ventricles are also associated with alterations on the putamen and thalamus. The complementarity of the information provided by the surface and pose analysis may help to identify abnormal white and grey matter growth, hinting toward a pattern of neural and cellular dysmaturation.

Intragenic suppression at the b2 locus in Ascobolus immersus. I. Identification of three distinct groups of suppression.

A reversion study of EMS- or ICR170-induced ascospore color mutants in Ascobolus immersus is reported. Twenty-three new intragenic suppressors were isolated within the b2 locus. These are localized within three distinct groups on a genetic fine-structure map containing 21 identifiable sites. The pattern of reversion is discussed according to the known specificity of EMS and ICR170 in Ascobolus immersus.

Productive infection of normal CD40-activated human B lymphocytes by HIV-1.

OBJECTIVE: Antigen-driven B-cell proliferation and maturation occur in germinal centres present in lymphoid tissues. This process is highly dependent on functional interactions between B and T lymphocytes. In vitro activation of CD40 present on B cells mimics B cell-T interactions and allows the proliferation of normal Epstein-Barr virus (EBV)-negative B lymphocytes. In HIV-1-seropositive individuals, B cells become exposed to free viral particles and to infected T lymphocytes while migrating through germinal centres. The effect of HIV-1 viral exposure on CD40-activated B lymphocytes was therefore examined. METHODS: Freshly isolated B lymphocytes were cultured in vitro through activation of CD40. B-cell proliferation, HIV-1 infectivity and viral production were monitored following B-lymphocyte exposure to HIV-1. In addition, HIV-mediated fusion between infected B cells and uninfected CD4+ T lymphocytes was assessed in a coculture assay. RESULTS: EBV-negative, CD40-activated human B lymphocytes were directly infected by HIV-1. The infection significantly reduced their proliferation rate. Viral production was detected in B-cell culture supernatant. Numerous fusion events indicated that HIV-1 infection of B lymphocytes could spread to T lymphocytes following HIV-1-mediated fusion of these two cell types. CONCLUSION: In view of the importance of B cell-T cell interactions in the maintenance of a functional immune system, disruption of B-lymphocyte development could have direct implications on the course of AIDS progression.

Encapsulation of foscarnet in liposomes modifies drug intracellular accumulation, in vitro anti-HIV-1 activity, tissue distribution and pharmacokinetics.

OBJECTIVE: To improve the in vitro anti-HIV-1 activity, intracellular accumulation in macrophages and in vivo pharmacokinetics and tissue distribution of foscarnet (trisodium phosphonoformate; PFA) by encapsulation in liposomes. METHODS: The accumulation of free and liposome-encapsulated PFA was determined in monocyte-macrophage RAW 264.7 cells and human premonocytoid U937 cells. The antiviral activity was evaluated in U937 cells infected with HIV-1IIIB. Tissue distribution and pharmacokinetics of free and liposomal PFA were determined in female Sprague-Dawley rats following the administration of an intravenous bolus dose (10 mg PFA/kg). RESULTS: The entrapment of PFA in liposomes resulted in a higher drug accumulation in both U937 and RAW 264.7 cells. A slightly greater efficacy against HIV-1IIIB replication into U937 cells was observed upon encapsulation of PFA into liposomes. Improved pharmacokinetics was observed upon entrapment of PFA in liposomes. Much higher drug levels were found in plasma for the liposomal formulation. The systemic clearance of the liposomal drug was 77 times lower than that of free drug. The encapsulation of PFA in liposomes greatly enhanced the drug accumulation in organs of the reticuloendothelial system. CONCLUSION: The encapsulation of PFA in liposomes modified the tissue distribution and plasma pharmacokinetics of the antiviral agent, resulting in a marked improvement of drug accumulation in organs involved in HIV immunopathogenesis and in a greater PFA bioavailability. The antiviral activity of liposomal PFA was slightly greater than that of free drug in HIV-1IIIB-infected U937 cells.

Haloperidol pretreatment unmasks the kappa opioid effects of U-50, 488H on cortical EEG and EEG power spectra in rats.

Adult female Sprague-Dawley rats were implanted with chronic cortical EEG electrodes and intravenous cannulae. U-50, 488H injection (5.0 mg/kg) produced initial EEG desynchrony and EEG spectral power that was mainly distributed over the zero to 10 Hz range, including a relatively small spectral peak in the 4-6 Hz band. In contrast, following haloperidol pretreatment (0.1 mg/kg), U-50, 488H injection produced high-voltage EEG bursts and a predominant EEG spectral peak in the 4-6 Hz band. These effects of U-50, 488H after haloperidol pretreatment were identical to those previously demonstrated with the benzomorphan kappa agonist ethylketocyclazocine. Thus, haloperidol pretreatment unmasked the kappa opioid effects of U-50, 488H.

Bloodborne markers in humans during multiday exposure to ozone.

Intermittent exposure of the human lung to ambient levels of ozone (O3) was assayed in systemic fluids by using serum alpha-tocopherol (ST) as a gauge of oxidative stress and the blastogenic activity of peripheral blood monocytes as an index of immune function. Healthy men (n = 10) were evaluated over 3 consecutive days (130 min/day) of chamber exposure to O3 and filtered air (FA); subjects alternated between rest and light treadmill exercise during exposures. For O3, the level was varied at 20-min intervals, i.e., 250, 350, 450, 450, 350, and 250 parts/billion, and concluded with 10 min at 250 parts/billion. ST was quantitated by high-performance liquid chromatography techniques, and T-lymphocyte blastogenesis was measured in cell cultures of peripheral blood monocytes by comparing [3H]thymidine incorporation in mitogen-stimulated (concanavalin A) and nonstimulated cells. After the third day of O3 at 20 h postexposure, ST levels were reduced significantly compared with the FA control subjects (down 14%; -0.96 mumol/l). Mitogen-activated T lymphocytes exhibited a 61% increase in blastogenic activity after 3 days of O3 exposure, significant compared with the proliferative activity of activated T lymphocytes collected after FA or before O3. Acute airway function was impaired by O3, e.g., on day 1, the forced vital capacity and forced expiratory volume in 1 s were decreased 8% (-0.92 liter) and 14% (-0.86 l/s), respectively, from preexposure values, and full recovery was delayed beyond 24 h. Effects of O3 exposure on cellular and biochemical markers increased in magnitude after each exposure and did not parallel the apparent adaptability of bronchial sensitivity to O3.

Relationship between regulation of morphine-induced EEG effects and changes in naloxone sensitivity.

The present data indicate that pretreatment with i.c.v. injection of dynorphin, morphine and dynorphin/morphine resulted in quantitative and qualitative changes in EEG power spectra in rats given i.c.v. morphine 24 h later. Correlated changes in sensitivity to antagonism of these EEG effects by naloxone were also found. Rats were implanted with cortical EEG electrodes and i.c.v. and i.v. cannulas. I.c.v. injections of morphine (20 micrograms/rat) produced high-voltage, slow-wave EEG bursts (1-10 Hz) associated with behavioral stupor which lasted about 2 h. Injections of i.c.v. morphine in rats pretreated with i.c.v. dynorphin (20 micrograms/rat), morphine (20 micrograms/rat) or dynorphin/morphine 24 h earlier, produced quantitative increases in absolute EEG spectral power. Injections of i.c.v. morphine in rats pretreated with i.c.v. dynorphin/morphine 24 h earlier, also produced qualitatively different EEG power spectra with a predominant peak in the 4-6 Hz band, similar to the EEG power spectra seen after acute administration of kappa opioids. After 20 min of morphine-induced high voltage EEG bursts, i.v. naloxone was given in sequential doses (0.0025, 0.0125, 0.025, 0.050 mg/kg) every 3 min until the EEG bursts were suppressed for 20 min. Relatively low doses of naloxone suppressed morphine-induced EEG bursts in rats that received i.c.v. H2O/H2O pretreatment. Slightly higher, but significant, doses of naloxone suppressed morphine-induced EEG bursts in rats that received i.c.v. H2O/morphine or dynorphin/H2O pretreatment. Moreover, a 10-fold increase in naloxone dose was needed to suppress EEG bursts in rats that received dynorphin/morphine pretreatment.(ABSTRACT TRUNCATED AT 250 WORDS)

[The daily public health nursing practice: the Montreal infectious diseases unit as an example]. / La pratique quotidienne des infirmières d'une direction de santé publique: l'exemple de l'unité maladies infectieuses à Montréal.

The health of urban populations depends on multiple factors, among them access to health and social services. The Montreal Public Health Department (PHD) is part of such services, where a number of nurses are working within a multidisciplinary team. It is through the description of the work accomplished by the team for infectious diseases control and prevention, and the vignettes of real life events related to the follow-up of syphilis, tuberculosis and hepatitis A cases, as well as quarantined individual exposed to SARS that the authors want to illustrate the work of the urban public health nurses. The examples are preceded by a description of the socio-demographic characteristics of the city of Montreal, that influence health problems, and therefore nurses' work.

Specificity and signaling in the Drosophila immune response.

The Drosophila immune response is characterized by the rapid and robust production of a battery of antimicrobial peptides immediately following infection. The genes encoding these antimicrobial peptides are controlled by two NF-κB signaling pathways that respond to microbial infection. The IMD pathway is triggered by DAP-type peptidoglycan, from the cell wall of most Gram-negative and certain Gram-positive bacteria, and activates the NF-κB precursor protein Relish. The Toll pathway, on the other hand, is stimulated by lysine-type peptidoglycan from many Gram-positive bacteria, ß 1,3 glucans from many fungi, as well as by microbial proteases. Toll signaling leads to the activation and nuclear translocation of DIF or Dorsal, two other NF-κB homologs. This review presents our current understanding of the molecular mechanisms involved in microbial recognition and signal transduction in these two innate immune pathways.

Disparity of gene conversion in frameshift mutants located in locus b2 of Ascobolus immersus.

The frequency of conversion and the disparity in the direction of conversion were studied for six frameshift mutants lying in locus b2 of Ascobolus immersus and giving more 2 wild type:6 mutant (2+6m) than 6 wild type:2 mutant (6+2m) aberrant asci (type B). The frequency of conversion decreased from left to right in the locus. The disparity steadily increased from left to right and then reached a plateau. Twenty-two frameshift mutants giving more 6+2m than 2+6m aberrant asci (type A) and closely linked to three type B mutants were also studied; they showed the same frequency of conversion and the same disparity (but in the opposite direction) as the type B mutant to which they are linked. The polar variation of both the frequency of conversion and the disparity as a function of position were expected on the basis of a previous study of 15 mutants giving postmeiotic segregations and located in locus b2. This variation is assumed to reflect the existence of a preferential region for the initiation of hybrid DNA (HDNA) during recombination and a duality in the distribution of this HDNA, with preponderant asymmetrical HDNA near the starting point and preponderant symmetrical HDNA farther from it.

[High frequency reversion of a spontaneous mutant in Ascobolus immersus]. / Haute fréquence de réversion d'un mutant spontané chez Ascobolus immersus

A spontaneous spore-colour mutation located in the gene b2 of A. immersus gives a high frequency of reversion. 8 distinct revertant phenotypes have been defined. The mutations corresponding to these revertants are located at the same site or very near the original mutation. The hypothesis that the mutation by itself is responsable for the observed reversions is advanced.

Human thymic dendritic cell-thymocyte association: ultrastructural cell phenotype analysis.

In rodent thymus, associations between dendritic cells (DC) and thymocytes have been suggested to be implicated in differentiation and/or maturation processes. In this study, we report intimate associations formed between human thymic DC and thymocytes in culture and we analyze their ultrastructural cell phenotype. Observations by phase contrast microscopy showed that DC present long and thin dendrites and bind many thymocytes. Transmission (TEM) and scanning electron microscopy (SEM) revealed that both cellular populations were in close connection and tight membrane contact could be observed. The phenotype of DC and attached thymocytes was characterized with a series of monoclonal antibodies by protein A-gold TEM and SEM immunolabelings. Quantitative evaluation of immunolabeling (number of gold granules/microns of cellular membrane) suggests the presence of two subpopulations of CD1+ thymic DC (strong and weak), whereas this discrepancy is not observed in DR+ and CD4+ DC populations. On the other hand, the majority of thymocytes bound to DC strongly express the CD1, CD4, CD8 and CD2 antigens and weakly the CD3 antigen, indicating that they represent double-positive immature thymocytes. Uniform distribution of DC and thymocytes membrane antigens was confirmed with a backscattered SEM study. This morphological and immunolabeling TEM and SEM analysis demonstrates that human thymic DC may form associations with CD4+CD8+CD3weak thymocytes and raises questions about their physiological relationship.

Repeated subacute ozone exposure of inbred mice: airway inflammation and ventilation.

The present study was designed to assess the effects of repeated subacute ozone (O3) exposure on pulmonary inflammation and ventilation in two inbred strains of mice differentially susceptible to a single O3 exposure. Susceptible C57BL/6J (B6) and resistant C3H/HeJ (C3) mice were exposed to 0.3 ppm O3 for 48 and 72 h and, after 14 days recovery, both strains were reexposed. Airway inflammation and lung injury were assessed by counting inflammatory cells and measuring total protein content and lactate dehydrogenase (LDH) activity in bronchoalveolar lavage (BAL) returns. Minute ventilation [VE, the product of breathing frequency (f), and tidal volume (VT)] was measured prior to and immediately following each exposure. After the initial exposure, B6 mice developed greater O3-induced increases in total protein, inflammatory cell influx, and LDH activity compared to C3 mice. In normal air, VE was also significantly elevated in B6, but not C3, mice after O3. The hypercapnic f of B6 and hypercapnic VT of C3 mice were significantly altered after O3 exposure. Reexposure to O3 caused a smaller increase in the numbers of macrophages, lymphocytes, epithelial cells, and BAL protein in both strains, and no changes in LDH activity. However, the number of polymorphonuclear leukocytes significantly increased in B6 and C3 mice as compared to the initial O3 exposure. In both strains, the ventilatory responses to normal air or hypercapnia were largely reproducible after O3 reexposure. Results indicated that differential susceptibility to O3-induced inflammation was maintained in B6 and C3 mice with O3 reexposure although the magnitude of the difference was reduced. Results also suggest that the ventilatory responses to O3 in B6 and C3 mice were reproducible with reexposure, and that airway inflammation and ventilation were not codependent.

PAF-induced airways hyperreactivity is modulated by mast cells in mice.

We tested the hypothesis that mast cells contribute to platelet-activating factor (PAF)-induced airways hyperreactivity and hyperpermeability in mice. Airways reactivity to acetylcholine (ACh) and lung permeability to Evans blue (EB) dye were measured before and after PAF challenge in genetically mast cell-deficient (WBB6F1 W/Wv) and normal congenic (WBB6F1 +/+) mice, as well as mast cell-reconstituted (BMT W/Wv) mice. In addition, prostaglandin D2 (PGD2), a mast cell-specific mediator, was measured in the bronchoalveolar lavage (BAL) from +/+ and W/Wv mice to determine if lung mast cell activation was a consequence of PAF challenge. Genetically PAF-sensitive AKR/J mice were also treated with the mast cell stabilizer nedocromil prior to assessment of PAF effects on ACh reactivity. Intravenous PAF (10 micrograms/kg) induced a significant (P < 0.05) increase in airways reactivity to ACh (25 micrograms/kg) in both +/+ (371 +/- 52%) and W/Wv (122 +/- 24%) mice. There was a significantly greater increase in +/+ compared with W/Wv mice. PAF-induced hyperreactivity to ACh in BMT W/Wv mice (191 +/- 44%) was significantly (P < 0.05) greater than age-matched W/Wv mice (80 +/- 16%), but not significantly different from age-matched +/+ mice (153 +/- 44%). PAF (10 micrograms/kg) also significantly (P < 0.5) increased lung permeability in +/+ and W/Wv mice, but there was no significant difference between groups. BAL PGD2 increased significantly in +/+ mice following PAF challenge (559 +/- 24 ng/ml) compared with vehicle controls (152 +/- 8 pg/ml). There was no significant increase in BAL PGD2 from W/Wv mice. Nedocromil pretreatment significantly (P < 0.05) decreased PAF-induced hyperreactivity in AKR/J mice but not in W/Wv mice (P > 0.05). We conclude that mast cells contribute significantly to PAF-induced hyperreactivity but not hyperpermeability in mice.

Comparative electroencephalographic and behavioral effects of phencyclidine, (+)-SKF-10,047 and MK-801 in rats.

Female Sprague-Dawley rats prepared with chronic i.v. cannulas and/or cerebrocortical electrodes were administered sequentially increasing doses of phencyclidine (PCP, 0.1-6.4 mg/kg/injection), (+)-SKF-10,047 [(+)-N-allynormetazocine] (0.4-25.6 mg/kg/injection) or MK-801 [(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]-cyclohepten-5,10-imine maleate] (0.01-0.64 mg/kg/injection). Effects on overt behavior, cortical EEG power spectra, locomotor activity and rotarod performance were assessed. Quantitative EEG spectral parameters (peak, mean and edge frequency; total and relative power; time domain descriptors mobility and complexity) were analyzed from the global frequency range of 1 to 50 Hz. Increasing doses of each drug produced increases in EEG spectra power from 1 to 50 Hz which was associated with a slowing of the peak frequency. PCP and MK-801 produced decreases in the mean frequency, mobility and edge frequency whereas (+)-SKF-10,047 produced increases in these spectral parameters. Moreover, (+)-SKF-10,047 increased complexity whereas MK-801 decreased complexity and PCP did not change this parameter. Total spectral power from 20 to 50 Hz was increased by (+)-SKF-10,047 and PCP, but was not changed by MK-801. Each drug increased spontaneous locomotor activity. At the highest doses, PCP and MK-801 decreased activity whereas (+)-SKF-10,047 was lethal. Each drug disrupted rotarod performance. The rank order of potency for each effect was: MK-801 greater than PCP greater than (+)-SKF-10,047. The data indicate that subtle differences in the effects of these drugs can be detected using EEG power spectral analysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Vitamin A deficiency enhances ozone-induced lung injury.

The present study determined the effects of vitamin A (vA) deficiency on the responses to ozone (O3) challenges in two inbred strains of mice that are differentially susceptible to O3-induced lung inflammation. Susceptible C57BL/6J (B6) and resistant C3H/HeJ (C3) dams at 2 wk gestation were fed test diets containing either 0 or 10 micrograms retinol/g diet. In mice that were maintained on vA-sufficient (vA+) diet, lung and liver tissue concentrations of vA and retinyl palmitate (RP) were significantly (P<0.05) lower in the B6 strain compared with C3, as measured by high-performance liquid chromatography techniques. vA and RP levels were significantly (P<0.05) reduced in lung and liver tissues of 8-wk old B6 and C3 mice that were maintained on a vA deficient (vA-) diet. vA+ and vA- mice of both strains were exposed to air or 0.3 ppm O3/72 h, and lung injury was assessed by differential cell count and total protein concentration in bronchoalveolar lavage (BAL) returns. O3 exposure caused significantly (P<0.05) greater increases in inflammatory cells and a total protein in BAL returns of vA+ B6 mice than vA+ C3 mice. vA deficiency significantly (P<0.05) enhanced O3-induced increases in polymorphonuclear leukocytes in C3 mice and epithelial cells loss in both strains. Compared with vA+ mice, lung permeability was also significantly (P<0.05) enhanced in vA- mice of both strains exposed to O3. vA replacement partially reversed the O3-induced lung injury that was enhanced by vA- diet. Results indicate that vA may have an important role in the pathogenesis of O3-induced lung injury in differentially susceptible inbred strains of mice.

Chronic ethanol consumption increases hepatic sinusoidal contractile response to endothelin-1 in the rat.

Recent evidence suggests that hepatic stellate cells function as liver-specific pericytes that are highly contractile in response to endothelin-1 (ET-1). Liver injury has been shown to lead to "activation" of stellate cells producing a phenotypic change to a more myofibroblastic cell type including loss of vitamin A and increased contractility. The present study was undertaken to test the effects of short-term chronic ethanol consumption (36% of total calories for 5 weeks according to the Lieber-DeCarli protocol) on hepatic vitamin A storage, expression of smooth muscle alpha-actin, and sinusoidal contractility in Sprague-Dawley rats. Using in vivo epifluorescence video microscopy, we quantified the number of sites of vitamin A fluorescence (purportedly stellate cells) and assessed sinusoidal microhemodynamics at baseline and during a 20-minute infusion period of ET-1 (1 pmol * 100 g body weight [bw]*1*min-1). Retinol and retinyl palmitate were measured after the experiment by means of high-pressure liquid chromatography (HPLC). A highly significant decrease in liver retinyl palmitate level (control: 622.5 +/- 50.9; ethanol: 273.0 +/- 38.0 microgram/g liver; P< .001) was found that correlated with a decrease in sites of vitamin A fluorescence (control: 531.4 +/- 76.1; ethanol: 141.1 +/- 30.2* mm-2; r = .82, P <.001). Concomitantly scattered expression of smooth muscle alpha-actin in sinusoids was observed. Although sinusoidal hemodynamics were not affected at baseline, a significant increase in sinusoidal contractility on endothelin-1 infusion (e.g., sinusoidal resistance [% of baseline value]: control: 10 minutes: 288.7 +/- 71.7, 20 minutes: 200.5 +/- 46.9; ethanol: 10 minutes: 1,916.0 +/- 701.7, 20 minutes: 656.8 +/- 103.3; P < .05 and .01, respectively) was observed. These data indicate that chronic ethanol consumption in this moderate model initiates stellate cell activation. Increased sinusoidal responsiveness to the vasoconstrictor ET-1 in vivo may contribute to the increased susceptibility of ethanol-fed rats to secondary stresses that increase ET-1 expression, such as endotoxemia.