A two-centre evaluation of the human organotypic skin explant culture model for screening contact allergens

Animal models are considered to be the "gold standard" for determining the potential contact allergenicity of low molecular weight chemicals. However, governmental regulations and ethical considerations limit the use of animals for such purposes. There is therefore a need for in vitro alternative models. The human organotypic skin explant culture (HOSEC) model is reported to be a promising alternative method for the predictive testing of contact allergens. The accelerated migration of Langerhans cells from the epidermis upon exposure to contact allergens is used to identify chemicals that are potentially capable of inducing a delayed-type hypersensitivity. In the study described in this paper, the model was further refined, and used, in two independent laboratories, to screen 23 low molecular weight compounds of known classification for their allergenicity. Each laboratory was able to accurately detect the contact allergens, despite small variations in the protocols used. However, the classification of dermal irritants, which have often been falsely classified as allergens, varied between the two laboratories. Despite the current limitations of the HOSEC model, the accuracy of the predictions made (sensitiser or non-sensitiser) compare favourably with classifications obtained with commonly used animal models. The HOSEC model has the potential to be developed further as an in vitro alternative to animal models for screening for contact allergens.     

Physiological Effects of Plant Hormones in Cotton Under Drought

Effects of plant hormones indole-3-yl-acetic acid (IAA), gibberellic acid (GA), benzylaminopurine (BAP), abscisic acid (ABA) and ethrel (ETH) in 5 M concentration on gas exchange, ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCO, EC 4.1.1.39) activity, pigment content and yield in cotton (Gossypium hirsutum L. cv. H-777) under drought were studied. At reproductive stage (55 – 60 d after sowing) these hormones were sprayed on shoots one day prior to stress imposition by withholding irrigation. The soil moisture of control plants was kept at field capacity. Net photosynthetic rate (P_N), stomatal conductance (g_s), transpiration rate (E), carboxylation efficiency (CE), water use efficiency (WUE), RuBPCO activity, boll number per plant, seed number per plant and lint mass per plant significantly decreased at drought while chlorophyll (Chl) b content and flower number per plant increased. ABA and ETH significantly reduced gas exchange parameters, Chl a and Chl b content. Detrimental drought effect on P_N, g_s, E, CE, RuBPCO and lint mass per plant was significantly alleviated by BAP and also its effect on seed number and lint mass per plant was significantly alleviated with the ABA treatment.     

Snapin interacts with the N-terminus of regulator of G protein signaling 7

The N-terminus of regulator of G protein signaling 7 (RGS7) contains a dishevelled/egl-10/pleckstrin (DEP) domain of unknown function. To gain insight into its function, we used yeast two-hybrid analysis to screen a human whole brain cDNA library in order to identify proteins that interact specifically with the N-terminus of human RGS7 (amino acid residues 1-248). From this analysis, we identified snapin, a protein associated with the SNARE complex in neurons, as an interactor with the N-terminus of RGS7. Deletion mutation analysis in yeast demonstrated that the interaction between RGS7 and snapin is specific and is mediated primarily by amino acid residues 1-69 of RGS7 (which contains the proximal portion of the DEP domain). The interaction between RGS7 and snapin was also demonstrated in mammalian cells by coimmunoprecipitation and pull-down assays. Our results suggest that RGS7 could play a role in synaptic vesicle exocytosis through its interaction with snapin.     

A palmitoylation switch mechanism in the regulation of the visual cycle

RPE65 is essential for the biosynthesis of 11-cis-retinal, the chromophore of rhodopsin. Here, we show that the membrane-associated form (mRPE65) is triply palmitoylated and is a chaperone for all-trans-retinyl esters, allowing their entry into the visual cycle for processing into 11-cis-retinal. The soluble form of RPE65 (sRPE65) is not palmitoylated and is a chaperone for vitamin A, rather than all-trans-retinyl esters. Thus, the palmitoylation of RPE65 controls its ligand binding selectivity. The two chaperones are interconverted by lecithin retinol acyl transferase (LRAT) acting as a molecular switch. Here mRPE65 is a palmitoyl donor, revealing a new acyl carrier protein role for palmitoylated proteins. When chromophore synthesis is not required, mRPE65 is converted into sRPE65 by LRAT, and further chromophore synthesis is blocked. The studies reveal new roles for palmitoylated proteins as molecular switches and LRAT as a palmitoyl transferase whose role is to catalyze the mRPE65 to sRPE65 conversion.     

Mean nuclear volume in ovarian papillary serous cystadenocarcinoma

OBJECTIVE: To measure mean nuclear volume (MNV), estimated by the stereologic intercept method, in ovarian serous carcinomas and to compare that between omentum-positive cases (cases with omental metastasis) and -negative cases. STUDY DESIGN: This retrospective study consisted of 29 cases (stage I and II = 13 cases, and stage IIIb = 16 cases) of ovarian papillary serous cystadenocarcinoma. MNV of all cases (at primary and metastatic sites) was estimated with an image cytometer. The nuclear point intersection method was used to measure nuclear volume. Mean intercepted diameters of at least 50 nuclei were measured. MNV was correlated with histologic grade, International Federation of Gynecology and Obstetrics (FIGO) staging of ovarian malignancy and primary tumor versus metastatic deposits. RESULTS: MNVs estimated in omentum-negative (FIGO stage I and II) and omentum-positive (FIGO stage IIIb) cases were 1,022.48 +/- 608.45 and 2,152 +/- 1,317.51 microns 3 (P = .05, Student t test), respectively. Significant differences in MNV were also observed among the different grades of tumor. However, no significant difference was observed between MNVs of primary and metastatic tumors in omentum-positive cases. CONCLUSION: Estimates of MNV on conventional histopathology sections may provide objective and useful criteria for relatively subjective histopathology grading and staging (FIGO stage I and II vs. IIIb).     

Mean nuclear volume in squamous cell carcinoma of the vulva

OBJECTIVE: To compare mean nuclear volume (MNV) estimated by the stereologic intercept method in lymph node-positive and -negative cases of squamous cell carcinoma of the vulva. STUDY DESIGN: This retrospective study consisted of 53 cases (lymph node metastasis, n = 19; cases without lymph node metastasis, n = 34) of squamous cell carcinoma of the vulva. MNV was estimated with the help of an image cytometer. The nuclear point intersection method was used to measure MNV. The mean nuclear volumes of both lymph node-positive and -negative cases were compared. RESULT: MNV in the lymph node-negative and -positive cases was 717.0 +/- 533.1 and 1,961.4 +/- 1,369.6 microns 3, respectively (P < .000, Mann-Whitney U test). There was a significant difference in MNV between the 2 groups of tumors. CONCLUSION: The observations from the present study suggest that estimation of MNV of malignant squamous cells from the vulva on conventional histopathology sections may provide an objective and useful diagnostic tool in predicting lymph node metastasis.