Synergistic control of keratinocyte adhesion through muscarinic and nicotinic acetylcholine receptor subtypes

The biological mechanisms involved in initiating, coordinating, and ultimately terminating cell-cell adhesion in the stratified epithelium are not well understood at present. This study was designed to elucidate the roles of the muscarinic M3, the nicotinic alpha3, and the mixed muscarinic-nicotinic alpha9 acetylcholine receptors in physiologic control of keratinocyte adhesion. Both muscarinic and nicotinic antagonists caused keratinocyte detachment and reversibly increased the permeability of keratinocyte monolayers, indicative of the involvement of both muscarinic and nicotinic pathways in the cholinergic control of keratinocyte adhesion. Since phosphorylation of adhesion proteins plays an important role in rapid assembly and disassembly of intercellular junctions, we measured muscarinic and nicotinic effects on phosphorylation of keratinocyte adhesion molecules. The phosphorylation levels of E-cadherin, beta-catenin, and gamma-catenin increased following pharmacological blockage of muscarinic receptors. Long-term blocking of alpha3, alpha9, and M3 receptor signaling pathways with antisense oligonucleotides resulted in cell-cell detachment and changes in the expression levels of E-cadherin, beta-catenin, and gamma-catenin in cultured human keratinocytes. Simultaneous inhibition of several receptor subtypes with a mixture of antisense oligonucleotides produced intensified abnormalities with cell adhesion. Moreover, altered cell-cell adhesion was found in the stratified epithelium of alpha3, alpha9, and M3 receptor knockout mice. Keratinocytes from these mice exhibited abnormal expression of adhesion molecules at both the protein and the mRNA levels. Thus, our data indicate that the alpha3, alpha9, and M3 acetylcholine receptors play key roles in regulating in a synergistic mode keratinocyte adhesion, most probably by modulating cadherin and catenin levels and activities. These findings may aid in the development of novel methods useful for the treatment of skin adhesion diseases and tumor metastasis.     

Discrete event modeling of CD4+ memory T cell generation

Studies of memory T cell differentiation are hampered by a lack of quantitative models to test hypotheses in silico before in vivo experimentation. We created a stochastic computer model of CD4+ memory T cell generation that can simulate and track 10(1)-10(8) individual lymphocytes over time. Parameters for the model were derived from experimental data using naive human CD4+ T cells stimulated in vitro. Using discrete event computer simulation, we identified two key variables that heavily influence effector burst size and the persistent memory pool size: the cell cycle dependent probability of apoptosis, and the postactivation mitosis at which memory T cells emerge. Multiple simulations were performed and varying critical parameters permitted estimates of how sensitive the model was to changes in all of the model parameters. We then compared two hypotheses of CD4+ memory T cell generation: maturation from activated naive to effector to memory cells (model I) vs direct progression from activated naive to memory cells (model II). We find that direct progression of naive to memory T cells does not explain published measurements of the memory cell mass unless postactivation expansion of the memory cell cohort occurs. We conclude that current models suggesting direct progression of activated naive cells to the persistent memory phenotype (model II) do not account for the experimentally measured size of the postactivation CD4+, Ag-specific, memory T cell cohort.     

HIV Infection,Risk Factors,and Preventive Services Utilization among Female Sex Workers in the Mekong Delta Region of Vietnam

Background

Risk behaviors among female sex workers (FSW) are considerable drivers of HIV infections in Vietnam, especially transmission between high-risk and low-risk groups. We assessed HIV prevalence and its correlates among FSWs, and the use of preventive services among this community in the Mekong Delta region, southern Vietnam.

Methods

A cross-sectional survey of 1,999 FSWs was carried out in five provinces including Ben Tre, Hau Giang, Kien Giang, Tien Giang, and Vinh Long between June, 2006 and June, 2007. We interviewed participants face-to-face in order to elicit information about their lives and potential risk factors, and we tested their sera to determine their HIV status. We then performed multivariate logistic regression analyses to investigate factors associated with HIV infection.

Results

Seventeen percent of the participating FSWs were street-based sex workers (SSWs) and the rest (83%) were entertainment establishment-based sex workers (ESWs). Unprotected sex with regular and casual clients in the past month was frequent among study participants (40.5% and 33.5% respectively). However, few respondents (1.3%) had ever injected drugs. Only 2.1% (95% confidence interval (CI): 1.6%–2.8%) of FSWs were found to be infected with HIV. HIV prevalence among SSWs was greater than among ESWs (3.8% vs. 1.8%, p = 0.02, respectively). Increased risk for HIV infection was significantly associated with the number of clients per month (adjusted odd ratio (aOR) = 2.65, 95% CI: 1.26–5.59).

Conclusions

Interventions to reduce unsafe sex and drug injection, and to increase uptake of HIV testing among FSWs are necessary. Differences in HIV prevalence and its correlates by type of sex work emphasize the importance of constrained contexts in shaping risk behaviors among FSWs; that should be considered in designing HIV prevention programs.     

31P NMR Studies of the Binding of the Oligonucleotide (Ap)3A to an Oligodeoxythymidylate Covalently Linked to an Acridine Derivative

Abstract

³¹P NMR was used to study the specific interaction of an oligodeoxynucleotide containing four thymines and covalently attached to an acridine derivative through its 3-phosphate [(Tp)₄(CH₂)₅Acr] with a complementary oligoribonucleotide (Ap)₃A.³¹P-¹H and ¹H-¹H chemical shift correlation spectroscopies were jointly used to provide the assignment of the phosphorus resonances. A downfield shift of two phosphorus resonances of (Tp)₄(CH₂)₅Acr and of two phosphorus resonances of (Ap)₄A was observed upon complex formation. The assignment of the phosphorus resonances which are downfield shifted allowed us to propose a model involving an equilibrium between several 1:1 complexes where the acridine ring is intercalated between different A.T base pairs.     

Oligonucleotide-Intercalant: Substances à Forte Affinité Spécifique pour les Séquences d'Acides Nucléiques Effets de I'Estérification des phosphates

Abstract

L'objectif est le contrôle sélectif de l'expression des gènes. Les composés oljgodN-bras-intercalant non modifies sur les phosphates (1–3) possedènt une forte affinité specifiqué pour les séquences nucléiques complémentaires. Af in d'améliorer ce système nous avons préparé des composés modifiés sur la chaîne nucléotidique.     

New Species and Eight Undescribed Species Belonging to the Families Aspergillaceae and Trichocomaceae in Korea

During a survey of fungal diversity associated with insects, mud, soil, and freshwater niches in different areas in Korea, nine interesting fungal strains were isolated. Based on their morphological characteristics and molecular phylogeny analyses, using a combined data set of β-tubulin (BenA), calmodulin (CaM), and second largest subunit of RNA polymerase (RPB2) sequences, the strains CNUFC AM-44, CNUFC JCW3-4, CNUFC S708, CNUFC WT202, CNUFC AS1-29, CNUFC JCW3-5, CNUFC JDP37, and CNUFC JDP62 were identified as Aspergillus alabamensis, A. floridensis, A. subversicolor, Penicillium flavigenum, P. laevigatum, P. lenticrescens, Talaromyces adpressus, and T. beijingensis, respectively. The strain CNUFC JT1301 belongs to series Westlingiorum in section Citrina and is phylogenetically related to P. manginii. However, slow growth when cultivated on CYA, MEA, CREA is observed and the property can be used to easily distinguish the new species from these species. Additionally, P. manginii is known to produce sclerotia, while CNUFC JT1301 strain does not. Herein, the new fungal species is proposed as P. aquadulcis sp. nov. Eight species, A. alabamensis, A. floridensis, A. subversicolor, P. flavigenum, P. laevigatum, P. lenticrescens, T. adpressus, and T. beijingensis, have not been previously reported in Korea. The present study expands the known distribution of fungal species belonging to the families Aspergillaceae and Trichocomaceae in Korea.     

CDK2 limits the highly energetic secretory program of mature β cells by restricting PEP cycle-dependent KATP channel closure

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Sequence-targeted photochemical modifications of nucleic acids by complementary oligonucleotides covalently linked to porphyrins

Porphyrins linked to oligonucleotides produce various types of photodamage on a complementary target DNA. The observed reactions include oxidation of guanine bases and cross-linking reactions of the oligonucleotide to its target sequence. Guanines located close to the porphyrin macrocycle were the most altered as compared to more remote guanines on the target sequence. No specific reaction was observed when the complexes were dissociated at temperatures above the melting temperature of the oligonucleotide-target hybrid. Both cross-linking and oxidation reactions accounted for ca. 60% modification of the target chains in the complex. Our results show that oligonucleotides covalently linked to porphyrins are efficient systems for inducing irreversible sequence-specific photodamage on a target DNA.     

Thermal stability of the Z conformation of the hexanucleoside pentaphosphate d(br5CGbr5CGbr5CG): evidence for a conformational transition before melting

The thermal stability of the hexanucleoside pentaphosphate d(br5CGbr5CGbr5CG) has been studied at two nucleotide concentrations, in the presence of 1 M NaClO4. At low nucleotide concentration (7 X 10(-5) M), circular dichroism experiments show a conformational transition from the Z conformation to another conformation, named X, which is not the B conformation, as the temperature is increased from 0 to 35 degrees C. Between 40 and 65 degrees C, another transition is observed which corresponds to the melting of the X conformation. At higher nucleotide concentration (2 X 10(-3) M), circular dichroism and 31P nuclear magnetic resonance experiments show that at low temperature (br5dC-dG)3 adopts the Z conformation. There are associations between the oligonucleotides which progressively disappear as the temperature increases. In the range 35-60 degrees C a transition from the Z conformation to another conformation is observed. This new conformation is the X conformation detected at low nucleotide concentration.