Monocular contribution to the peak time of the binocular pattern visual evoked potential

The contribution of each monocular pathway to the timing of the binocular pattern visual evoked potential was assessed in situations where a significant interocular timing discrepancy was observed. Monocular and binocular pattern visual evoked potentials to 0.5° checks were recorded from normal subjects, normal subjects in whom one eye was blurred, patients with monocular amblyopia, and patients with resolved unilateral optic neuritis. Normal subjects showed facilitation, while suppression was evidenced in subjects with monocular blurring. In patients with amblyopia, the affected pathway had no effect on binocular pattern visual evoked potential latency, suggesting that the amblyopic eye was suppressed. In contrast, all patients with optic neuritis showed binocular averaging. Our results show that different forms of binocular interaction are evidenced in normal subjects, in amblyopia and in optic neuritis, and suggest that a comparative analysis of monocular and binocular pattern visual evoked potential peak times brings valuable information to the clinical evaluation that could be used to distinguish disease processes further.Abbreviation BPVEP binocular pattern visual evoked potential     

Invasive and non-invasive studies of the protective action of a silicon-containing cream and its excipient in skin irritation induced by sodium laurylsulfate

The purpose of our study was to evaluate the protective effect of a new silicone-containing barrier-cream (Anthydro) and its vehicle (Anthydro without silicone) in the prevention of cutaneous irritation by detergents. We therefore planned a study in several stages, using an anionic surfactant well known for its irritant properties: sodium laurylsulphate (SLS) in aqueous solution. In a first series of experiments, the protective effect of the Anthydro cream against SLS was studied by invasive methods on guinea-pigs in order to determine histologically the protective effect of the cream when a 10 p. 100 SLS solution was applied on the skin under occlusion during 24 hours (Square chambers, Van der Bend). Typical and reproducible lesions were apparent, and the protected sites were compared with the unprotected sites. In parallel, we used non-invasive methods (conductivity, transepidermal water loss and cutaneous blood flow) to determine in humans the protective effect of Anthydro cream in comparison with unprotected sites after application during 24 hours of patches soaked with a 5 p. 100 SLS solution on the forearms of 13 adult and healthy volunteers (Silver patch tests, Van der Bend). In both experiments the Anthydro cream was effective in reducing the SLS-induced cutaneous irritation. In a second series of experiments, the Anthydro barrier-cream was compared with its "base" (Anthydro without silicone) in terms of effectiveness, following the same experimental procedure (invasive on guinea-pigs, and non-invasive on humans). The base was shown to be effective in protecting against irritation. However, the histological lesions were less intense when the skin was protected by Anthydro than by its vehicle. Concerning the non-invasive methods in humans, no significant statistical differences appeared in the measurement of various parameters between the sites protected by Anthydro and the sites protected by the vehicle. These results lead us to suggest the existence of an essentially mechanical protective effect in which the silicone plays a very small part in terms of effectiveness. These experimental results necessitates further investigations to be extrapolated to occupational conditions without tests performed in industries and well-conducted epidemiological investigations.     

The diagnostic use of the second oscillatory potential in clinical electroretinography

Of all the electroretinogram (ERG) components (a-wave, b-wave, and oscillatory potentials) only one oscillatory potential, OP₂, was found to be significantly correlated with the absolute intensity of the flash stimulus (i.e., the intensity of the stimulus irrespective of the state of retinal adaptation). Our finding was further confirmed in single cell recordings of lateral geniculate unit activity in rabbits in which peak time of OP₂ was found to correlate better with the geniculate activity. For these reasons we have identified OP₂ as the intensity coding oscillatory potential of the ERG. In order to investigate if this new feature could have some clinical significance, we examined photopic ERGs recorded from patients affected with various retinopathies. In most instances the peak time of OP₂ paralleled that of the b-wave, that is, in the ERG with delayed b-wave the peak time of OP₂ was also delayed, while in ERGs with normal b-wave peak time the peak time of OP₂ was also normal. However, in some conditions (especially in cone-rod diseases) a delayed OP₂ was found in ERGs with normal b-wave peak times.     

Flow-Cytometric Characterization of Hematopoietic Cells in Non-Pregnant Human Endometrium

Lachapelle M-H, Miron P, Hemmings R, Baron C, Roy DC. Flow-cytometric characterization of hematopoietic cells in non-pregnant human endometrium. Am J Reprod Immunol 1996; 35:5–13 cP Munksgaard, Copenhagen PROBLEM: Immunologic evaluation and quantitation of hematopoietic cells in human endometrium has been difficult to perform, particularly in nonpregnant subjects. In this study, we describe a method for the flow-cytometric characterization of hematopoietic cells present in the endometrium of non-pregnant women. METHOD: Endometrial biopsy samples from normal donors were first mechanically disrupted and filtered to generate a single-cell suspension of leukocyte-enriched endometrial cells. Cells were labeled with a panel of monoclonal antibodies, stained with propidium iodide (PI), and one- or two-color flow-cytometric analysis performed on cells excluding PI. RESULTS: The methodology described in this study was highly reproducible in experiments evaluating the interrun and intrarun variability. We then determined the immunophenotypic profile of endometrial leukocytes from 12 normal females. The majority of leukocytes were T cells (CD3: 47%; CD4: 24%; CD8: 28%) with an important contingent of NK cells (CD56: 32%), the majority of which harbored the unusual CD16-CD56 bright phenotype, and a minority of B cells (CD20: 6%) and monocytes (CD14: 7%). CONCLUSIONS: Flow cytometry can be used to assess antigen expression on the surface of endometrial leukocytes from nonpregnant women. In future studies, it will be possible to use this approach to investigate the role of immune cell populations in the endometrium of patient experiencing reproductive failure.     

Glial Transplants: An in vivo Analysis of Extrinsic and Intrinsic Determinants of Dysmyelination in Genetic Variants

Myelination in the CNS depends on the ability of oligodendrocytes (Ols) to efficiently colonize the brain, differentiate, and express a precise balance of specific genes necessary for myelin synthesis. Mutations in these genes produce different types of dysmyelinisation in animal as in human. Defects in the synthesis of myelin constituents usually lead to mild dysmyelinations. In contrast, mutations affecting the gene encoding the proteolipid, another major protein of myelin, produce various perturbations of Ols biology suggesting a pleiotropic effect of the gene in the development of the CNS. Studies on expansion of cell population and survival have provided contradictory information on the extrinsic and intrinsic action of the gene on Ols biology. On one hand, in vitro studies using conditioned media as in vivo studies on heterozygotes, and transplantations experiments suggest that excess of programmed cell death in these mutants is ruled out by intrinsic factors which could act during embryonic life. On the other hand, attempts to compensate the gene defect by transgenic correction demonstrate a dominant negative effect of the jp mutation on both survival and functional potential of Ols. Finally, total suppression of PLP gene expression has a restricted effect on myelin structure without excess of cell death. These contradictory results are discussed in the perspective of regulation of cell death by competition for growth factors in limiting amount. The proposed model suggests that this contradiction is only apparent, and that excess of cell death in PLP/DM20 mutant is intrinsically determined by diminished competitivity of the mutant Ols for limited amounts of environmental factors.     

Mouse oligospheres: from pre-progenitors to functional oligodendrocytes

To study the biology and repair capacities of mouse oligodendroglial cells, we established cultures of cells purified from neonatal wild-type and 9.6-kb MBP-LacZ transgenic newborn mice cerebral hemispheres as free-floating aggregates in the continuous presence of neuroblastoma conditioned medium (N1-B104). In vitro analysis indicated that the initial cell preparations were enriched in oligodendrocyte pre-progenitors that expressed PSA-NCAM and GAP-43 but not GD3, O4, NF68 or glial fibrillary acidic protein (GFAP) markers. These pre-progenitors required increased concentrations of insulin and progesterone to allow their survival in vitro. With time in culture, spheres composed of oligodendrocyte pre-progenitors became oligospheres enriched in oligodendrocyte progenitors expressing GAP-43 and GD3. As well as conserving bipotentiality in vitro, these spheres were able to form myelin in vivo after transplantation into the neonatal shiverer mouse brain. Thus, the oligosphere strategy is a powerful method for generating large populations of mouse oligodendrocyte pre-progenitors and progenitors. The ability to generate oligospheres from transgenic mice will be instrumental in the further dissection of the molecular and cellular mechanisms of myelination and remyelination of the central nervous system.     

Diesel engine exhaust exposure in underground mines: Comparison between different surrogates of particulate exposure

Exposure to diesel particulate matter (DPM) is frequently assessed by measuring indicators of carbon speciation, but these measurements may be affected by organic carbon (OC) interference. Furthermore, there are still questions regarding the reliability of direct-reading instruments (DRI) for measuring DPM, since these instruments are not specific and may be interfered by other aerosol sources. This study aimed to assess DPM exposure in 2 underground mines by filter-based methods and DRI and to assess the relationship between the measures of elemental carbon (EC) and the DRI to verify the association of these instruments to DPM. Filter-based methods of respirable combustible dust (RCD), EC, and total carbon (TC) were used to measure levels of personal and ambient DPM. For ambient measurements, DRI were used to monitor particle number concentration (PNC; PTrak), particle mass concentration (DustTrak DRX and DustTrak 8520), and the submicron fraction of EC (EC_1;Airtec). The association between ambient EC and the DRI was assessed by Spearman correlation. Geometric mean concentrations of RCD, respirable TC (TC_R) and respirable elemental EC (EC_R) were 170 µg/m³, 148 µg/m³, and 83 µg/m³ for personal samples, and 197 µg/m³, 151 µg/m³, and 100 µg/m³ for ambient samples. Personal measurements had higher TC_R:EC_R ratios compared to ambient samples (1.8 vs. 1.50) and weaker association between EC_R and TC_R. Among the DRI, the measures of EC₁ by the Airtec (ρ = 0.86; P < 0.001) and the respirable particles by the DustTrak 8520 (ρ = 0.74; P < 0.001) showed the strongest association with EC, while PNC showed a weak and non-significant association with EC. In conclusion, this study provided important information about the concentrations of DPM in underground mines by measuring several indicators using filter-based methods and DRI. Among the DRI, the Airtec proved to be a good tool for estimating EC concentrations and, although the DustTrak showed good association with EC, interferences from other aerosol sources should be considered when using this instrument to assess DPM.     

Risk Factors and Birth Outcomes of a High-Risk Cohort of Women Served by a Community-Based Prenatal Home Visiting Program

Our study explored risk factors and birth outcomes of a community maternal and child outreach program for high poverty mothers in East and Central Harlem. We conducted a retrospective chart review of 75 mother–infant dyads, with singleton pregnancies, receiving antepartum and postpartum home visits. Inexperienced parenting was associated with increased odds of giving birth to an infant weighing <2,700 g compared to experienced parenting after adjustment for race/ethnicity and preeclampsia diagnosis (odds ratio (OR) 4.9, p = 0.04). Mothers had comparatively lower depression risk in the postpartum period compared to antepartum (p = 0.006).     

Skin tolerability associated with transdermal drug delivery systems: an overview

As transdermal patches become more widely prescribed, it is important that clinicians understand: (a) the common causes of skin reactions with these medications; (b) how to minimize these reactions; and (c) how to manage the signs and symptoms. Here we review published data for skin reactions with patch medications approved within the past decade. Overall, the most common application site signs and symptoms appear to be localized redness (erythema) or itching, sometimes accompanied by swelling (edema). Typically, these are mild to moderate in severity, transient in nature, and occur in 20% to 50% of patients. Most are localized to the area of application, and resolve spontaneously within several days following patch removal. Discontinuations due to these types of event are infrequent, ranging from 1.7% to 6.8% in the 6-month trials reviewed here. Based on expert opinion, the majority of these skin reactions would be a form of irritant contact dermatitis, with infrequent cases of allergic contact dermatitis. These types of reactions usually cause minimal pain or discomfort to the patient, and are unlikely to be of medical concern. Signs and symptoms of irritant contact dermatitis may be minimized by rotation of the application site, careful removal of the patch, and appropriate use of moisturizers and topical corticosteroids. In conclusion, the potential advantages of transdermal patches usually outweigh any additional skin issues; however, further research into treatment and management strategies is required.