Toward a unified theory of sexual mixing and pair formation.

Sexually transmitted diseases such as gonorrhea, syphilis, herpes, and AIDS are driven and maintained in populations by epidemiological and sociological factors that are not completely understood. One such factor is the way in which people mix sexually. In this paper, we outline a unified approach to modeling sexual mixing structures, where such structures are defined in terms of a set of axioms for a finite number of distinct groups of people. Theorems for homosexual, heterosexual, and arbitrary group mixing are presented, leading to a representation of all mixing structures defined by the axioms. The representation and its parameters are interpreted in terms of intergroup affinities for sexual mixing. The use of the approach in sexually transmitted disease modeling is discussed.     

LincRNA-Cox2 promotes pulmonary arterial hypertension by regulating the let-7a-mediated STAT3 signaling pathway

Molecular and Cellular Biochemistry - Long non-coding RNA FOXD3-AS1 is associated with allergic rhinitis (AR). This article aims to demystify the role of FOXD3-AS1 in AR. We compared FOXD3-AS1...     

Dexamethasone prevents the growth inhibitory effects of recombinant tumor necrosis factor in a rat hepatoma cell line Reuber-RC-3: an association with the changes in the messenger RNA levels for multidrug resistance gene.

Two days exposure to recombinant tumor necrosis factor (rTNF-alpha) produced a dose-dependent reduction in (methyl-3H) thymidine incorporation in RC-3 cells (ID50 = 25 units/ml). Prolonged treatment with rTNF-alpha further resulted in a significant reduction in colony formation (ID50 = 200 units/ml), which was reversed upon removal of the agent. Interferon levels were undetectable in the supernatants of the rTNF-alpha treated cells. Simultaneous exposure to dexamethasone prevented the growth inhibition in rTNF-alpha-treated RC-3 cells. Significant dose-dependent increase in the steady state levels of the mRNA for multidrug resistance (MDR1) gene was observed after rTNF-alpha treatment while simultaneous exposure to dexamethasone produced a substantial reduction in the mRNA levels for MDR1 gene. These data suggest that growth inhibitory effects of TNF are regulated by dexamethasone and are associated with changes in MDR1 mRNA levels in hepatoma-derived cells.     

Self-association of glutamic acid-rich fusion peptide analogs of influenza hemagglutinin in the membrane-mimic environments: Effects of positional difference of glutamic acids on side chain ionization constant and intra- and inter-peptide interactions deduced from NMR and gel electrophoresis measurements

Two glutamic acid-rich fusion peptide analogs of influenza hemagglutinin were synthesized to study the organization of the charged peptides in the membranous media. Fluorescence and gel electrophoresis experiments suggested a loose association between the monomers in the vesicles. A model was built which showed that a positional difference of 3, 7 and 4, 8 results in the exposure of Glu3 and Glu7 side chains to the apolar lipidic core. Supportive results include: first, pK_a values of two pH units higher than reference value in aqueous medium for Glu3 and Glu7 CγH, whereas the deviation of pK_a from the reference value for Glu4 and Glu8 CγH is substantially smaller; second, Hill coefficients of titration shift of these protons indicate anti-cooperativity for Glu3 and Glu7 side chain protons but less so for Glu4 and Glu8, implying a strong electrostatic interaction between Glu3 and Glu7 possibly resulting from their localization in an apolar environment; third, positive and larger titration shift for NH of Glu3 is observed compared to that of Glu4, suggesting stronger hydrogen bond between the NH and the carboxylic group of Glu3 than that of Glu4, consistent with higher degree of exposure to hydrophobic medium for the side chain of Glu3.     

Predominance of Single Prophage Carrying a CRISPR/cas System in “Candidatus Liberibacter asiaticus” Strains in Southern China

“Candidatus Liberibacter asiaticus” (CLas) is an uncultureable α-proteobacterium associated with citrus Huanglongbing (HLB, yellow shoot disease), a highly destructive disease affecting citrus production worldwide. HLB was observed in Guangdong Province of China over a hundred years ago and remains endemic there. Little is known about CLas biology due to its uncultureable nature. This study began with the genome sequence analysis of CLas Strain A4 from Guangdong in the prophage region. Within the two currently known prophage types, Type 1 (SC1-like) and Type 2 (SC2-like), A4 genome contained only a Type 2 prophage, CGdP2, namely. An analysis on CLas strains collected in Guangdong showed that Type 2 prophage dominated the bacterial population (82.6%, 71/86). An extended survey covering five provinces in southern China also revealed the predominance of single prophage (Type 1 or Type 2) in the CLas population (90.4%, 169/187). CLas strains with two and no prophage types accounted for 7.2% and 2.8%, respectively. In silico analyses on CGdP2 identified a CRISPR (clustered regularly interspaced short palindromic repeats)/cas (CRISPR-associated protein genes) system, consisting of four 22 bp repeats, three 23 bp spacers and 9 predicted cas. Similar CRISPR/cas systems were detected in all 10 published CLas prophages as well as 13 CLas field strains in southern China. Both Type 1 and Type 2 prophages shared almost identical sequences in spacer 1 and 3 but not spacer 2. Considering that the function of a CRISPR/cas system was to destroy invading DNA, it was hypothesized that a pre-established CLas prophage could use its CRISPR/cas system guided by spacer 1 and/or 3 to defeat the invasion of the other phage/prophage. This hypothesis explained the predominance of single prophage type in the CLas population in southern China. This is the first report of CRISPR/cas system in the “Ca. Liberibacter” genera.     

Peptide-specific antibodies employed in determining the interspecies immunological cross-reactivity of haemopexin

1. Antibodies were raised in rabbits against nine peptides analogous to sequences of the human serum beta-glycoprotein haemopexin, and seven peptides were very antigenic. 2. One of these affinity-purified peptide-specific antibodies interacted with a highly conserved sequence of the haemopexin of five of the seven species tested. 3. Another antibody bound pig haemopexin even better than human haemopexin. 4. The overall, arbitrarily assessed, immunological cross-reactivity between the haemopexin of human and other species follows the order: rabbit greater than mouse greater than chicken greater than pig greater than rat greater than cow.     

Estimations of the joint distribution of failure time and failure type with dependent truncation

In biomedical studies involving survival data, the observation of failure times is sometimes accompanied by a variable which describes the type of failure event (Kalbeisch and Prentice, 2002). This paper considers two specific challenges which are encountered in the joint analysis of failure time and failure type. First, because the observation of failure times is subject to left truncation, the sampling bias extends to the failure type which is associated with the failure time. An analytical challenge is to deal with such sampling bias. Second, in case that the joint distribution of failure time and failure type is allowed to have a temporal trend, it is of interest to estimate the joint distribution of failure time and failure type nonparametrically. This paper develops statistical approaches to address these two analytical challenges on the basis of prevalent survival data. The proposed approaches are examined through simulation studies and illustrated by using a real data set.