B cell progenitors are arrested in maturation but have intact VDJ recombination in the absence of Ig-alpha and Ig-beta

Ig-alpha and Ig-beta mediate surface expression and signaling of diverse B cell receptor complexes on precursor, immature, and mature B cells. Their expression begins before that of the Ig chains in early progenitor B cells. In this study, we describe the generation of Ig-alpha-deficient mice and their comparative analysis to mice deficient for Ig-beta, the membrane-IgM, and recombination-activating gene 2 to determine the requirement of Ig-alpha and Ig-beta in survival and differentiation of pro-B cells. We find that in the absence of Ig-alpha, B cell development does not progress beyond the progenitor stage, similar to what is observed in humans lacking this molecule. However, neither in Ig-alpha- nor in Ig-beta-deficient mice are pro-B cells impaired in V(D)J recombination, in the expression of intracellular Ig micro-chains, or in surviving in the bone marrow microenvironment. Finally, Ig-alpha and Ig-beta are not redundant in their putative function, as pro-B cells from Ig-alpha and Ig-beta double-deficient mice are similar to those from single-deficient animals in every aspect analyzed.     

Quantitation of breast sensibility following reduction mammaplasty: a comparison of inferior and medial pedicle techniques

The preservation of sensitivity within the nipple-areola complex is of paramount importance to patients presenting for reconstructive and aesthetic breast procedures. Previous attempts to measure sensation in the breast before and after surgery have relied primarily on the Semmes-Weinstein monofilament test, which is an imprecise study that measures the logarithm of force necessary to bend a series of six to 20 filaments. Within the last 10 years, various authors have published normative pressure threshold data for the breast that have varied by a magnitude of greater than 10-fold. Recently, precise anatomic studies have been performed that have elucidated the innervation of the nipple-areola complex medially and laterally from cutaneous branches of the intercostal nerves. Despite this knowledge, no quantitative sensibility studies have yet been performed that compare postoperative sensation when medially versus laterally innervated pedicles have been used in reduction mammaplasty. The present study is the first to use computer-assisted neurosensory testing to generate normal breast sensation data and to compare sensory outcomes between the inferior and the medial pedicle techniques of reduction mammaplasty.A total of 34 patients were divided into four groups and underwent breast sensory testing (67 breasts total) using the Pressure-Specified Sensory Device, a computer-assisted force transducer that measures static and moving one and two-point discrimination. Sensation in the nipple and in the four quadrants of the areola was measured. Groups I and II were composed of 17 unoperated controls with breast sizes ranging from 34A to 36C (group I; 18 breasts) and 36DD to 46EE (group II; 16 breasts) who presented to a general plastic surgery clinic. Groups III and IV were composed of 17 patients who underwent either medial or inferior pedicle reduction mammaplasty between July of 1997 and March of 1999. Pressure thresholds in the most sensitive breasts were as low as 0.3 g/mm2, a marked contrast to data from previous studies using Semmes-Weinstein monofilaments documenting the lowest recordable pressure threshold as greater than 2 g/mm2. Several findings from previous studies using Semmes-Weinstein monofilament testing were confirmed in unoperated controls, including an inverse relationship between sensitivity and breast size, superior nipple sensitivity when compared with the areola, and significant interpatient variability with respect to static and moving two-point discrimination among women matched according to age and breast size. When comparing medial with inferior pedicle reduction mammaplasty patients, it was found that despite significantly greater reductions using the medial pedicle technique (mean of 1.7 kg versus 1.1 kg of breast tissue removed), there were no significant differences in postoperative sensory outcomes in the sample size of 17 patients. Furthermore, within each group of patients undergoing either the medial or inferior pedicle technique, the amount of breast tissue removed did not correlate with postoperative sensory outcomes.Computer-assisted quantitative neurosensory testing is a highly accurate technique for measuring sensibility. The use of this technology demonstrates a 10-fold difference in measurable sensory thresholds in normal patients from preexisting data using Semmes-Weinstein monofilaments. Advances in measurement methods have allowed the authors to compare postoperative sensory outcomes reliably using two popular techniques of reduction mammaplasty.     

Two issues in archaeological phylogenetics: taxon construction and outgroup selection

Cladistics is widely used in biology and paleobiology to construct phylogenetic hypotheses, but rarely has it been applied outside those disciplines. There is, however, no reason to suppose that cladistics is not applicable to anything that evolves by cladogenesis and produces a nested hierarchy of taxa. This includes cultural phenomena such as languages and tools recovered from archaeological contexts. Two methodological issues assume primacy in attempts to extend cladistics to archaeological materials: the construction of analytical taxa and the selection of appropriate outgroups. In biology the species is the primary taxonomic unit used, irrespective of the debates that have arisen in phylogenetic theory over the nature of species. Also in biology the phylogenetic history of a group of taxa usually is well enough known that an appropriate taxon can be selected as an outgroup. No analytical unit parallel to the species exists in archaeology, and thus taxa have to be constructed specifically for phylogenetic analysis. One method of constructing taxa is paradigmatic classification, which defines classes (taxa) on the basis of co-occurring, unweighted character states. Once classes have been created, a form of occurrence seriation-an archaeological method based on the theory of cultural transmission and heritability-offers an objective basis for selecting an outgroup.     

"Living" under the challenge of information decay: the stochastic corrector model vs. hypercycles

The combined problem of having a large genome size when the accuracy of replication was a limiting factor is probably the most difficult transition to explain at the late stages of RNA world. One solution has been to suggest the existence of a cyclically coupled system of autocatalytic and cross-catalytic molecular mutualists, where each member helps the following member and receives help from the preceding one (i.e., a "hypercycle"). However, such a system is evolutionarily unstable when mutations are taken into account because it lacks individuality. In time, the cooperating networks of genes should have been encapsulated in a cell-like structure. But once the cell was invented, it closely aligned genes' common interests and helped to reduce gene selfishness, so there was no need for hypercycles. A simple package of competing genes, described by the "stochastic corrector model" (SCM), could have provided the solution. Until now, there is no clear demonstration that the proposed mechanisms (compartmentalized hypercycles and the stochastic corrector model) do in fact solve the error threshold problem. Here, we present a Monte Carlo model to test the viability of protocell populations that enclose a hypercyclic (HPC) or a non-hypercyclic (SCM) system when faced with realistic mutation rates before the evolution of efficient enzymic machinery for replication. The numerical results indicate that both systems are efficient information integrators and are able to overcome the danger of information decay in the absence of accurate replication. However, a population of SCM protocells can tolerate higher deleterious mutation rates and reaches an equilibrium mutational load lower than that in a population of HPC protocells.     

Genetic dissection of a major Fusarium head blight QTL in tetraploid wheat

The devastating effect of Fusarium head blight (FHB) caused by Fusarium graminearum has led to significant financial losses across the Upper Midwest of the USA. These losses have spurred the need for research in biological, chemical, and genetic control methods for this disease. To date, most of the research on FHB resistance has concentrated on hexaploid wheat (Triticum aestivum L.) lines originating from China. Other sources of resistance to FHB would be desirable. One other source of resistance for both hexaploid wheat and tetraploid durum wheat (T. turgidum L. var. durum) is the wild tetraploid, T. turgidum L. var. dicoccoides (T. dicoccoides). Previous analysis of the `Langdon'-T. dicoccoides chromosome substitution lines, LDN(Dic), indicated that the chromosome 3A substitution line expresses moderate levels of resistance to FHB. LDN(Dic-3A) recombinant inbred chromosome lines (RICL) were used to generate a linkage map of chromosome 3A with 19 molecular markers spanning a distance of 155.2 cM. The individual RICL and controls were screened for their FHB phenotype in two greenhouse seasons. Analysis of 83 RICL identified a single major quantitative trait locus, Qfhs.ndsu-3AS, that explains 37% of the phenotypic or 55% of the genetic variation for FHB resistance. A microsatellite locus, Xgwm2, is tightly linked to the highest point of the QTL peak. A region of the LDN (Dic-3A) chromosome associated with the QTL for FHB resistance encompasses a 29.3 cM region from Xmwg14 to Xbcd828.     

T-kininogen inhibits kinin-mediated activation of ERK in endothelial cells

Serum levels of T-kininogen increase dramatically as rats approach the end of their lifespan. Stable expression of the protein in Balb/c 3T3 fibroblasts leads to a dramatic inhibition of cell proliferation, as well as inhibition of the ERK signaling pathway. T-kininogen is a potent inhibitor of cysteine proteinases, and we have described that the inhibition of ERK activity occurs, at least in part, via stabilization of the MAP kinase phosphatase, MKP-1. Since fibroblasts are not a physiological target of T-kininogen, we have now purified the protein from rat serum, and used it to assess the effect of T-kininogen on endothelial cells. Adding purified T-kininogen to EAhy 926 hybridoma cells resulted in inhibition of basal ERK activity levels, as estimated using appropriate anti-phospho ERK antibodies. Furthermore, exogenously added T-kininogen inhibited the activation of the ERK pathway induced by either bradykinin or T-kinin. We conclude that the age-related increase in hepatic T-kininogen gene expression and serum levels of the protein could have dramatic consequences on endothelial cell physiology, both under steady state conditions, and after activation by cell-specific stimuli. Our results are consistent with T-kininogen being an important modulator of the senescent phenotype in vivo.     

Pig vitreous gel: macromolecular composition with particular reference to hyaluronan-binding proteoglycans

The aim of this study was to examine the macromolecular composition of pig vitreous body with particular emphasis on hyaluronan-binding proteoglycans. The whole pig vitreous gel was found to contain 76 microg of hyaluronan-derived uronic acid, 700 microg of total protein and 150 microg of collagen per ml of gel. The contents of neutral hexoses and sialic acids were 80 and 22 microg/ml of vitreous gel, but only a minor proportion of them were found to be associated with the proteoglycan fraction. As estimated by gel chromatography on Sepharose CL-2B, hyaluronan presents a polydisperse hydrodynamic behavior with a lower molecular mass (M(r)) value of 220 kDa. The existence of low amounts of a hyaluronan-binding proteoglycan population with structural and immunological characteristics similar to a member of the hyalectan family, versican, has also been demonstrated. The concentration of this versican-like proteoglycan in whole vitreous accounts for 50 microg proteoglycan protein per ml of vitreous gel and represents a minor proportion (about 7%) of the total protein content. The proteoglycan has an average M(r) of 360 kDa and is substituted by chondroitin sulphate (CS) side chains. Study of the CS sulphation pattern showed that the chains were composed of both type 4- and 6-sulphated disaccharide units.     

Biosensors for rapid monitoring of primary-source drinking water using naturally occurring photosynthesis

Working with primary-source freshwater drinking samples from the Clinch and Tennessee Rivers, we have developed a tissue-based biosensor detection system that uses naturally occurring aquatic photosynthetic tissue as the sensing material for detection of chemical antagonists in the water. Sensor readout is based on well-known principles of fluorescence induction by living photosynthetic tissue. The Clinch River is the main source of drinking water for Oak Ridge, Tennessee, while the Tennessee River is a major source for the city of Knoxville. We have successfully detected algae in every sample that we examined and readily monitored changes in the characteristic fluorescence induction curves when the samples were exposed to potassium cyanide (KCN), methyl parathion (MPt), N'(3,4-dichlorophenyl)-N,N-dimethylurea (DCMU), and paraquat. The percentage decreases in photochemical yields observed in Tennessee River samples after a 24-min exposure to KCN, MPt, and DCMU were, respectively, 21.89+/-0.76, 3.28+/-0.18, and 14.77+/-1.81. For a site at the Clinch River, the percentage decreases were 22.78+/-1.63, 8.32+/-0.21, and 17.71+/-1.32 (Table 1). The unique aspect of this approach to real-time water quality monitoring is that unlike conventional sensing devices, this sensor material is external to the detecting instrument and is continuously refreshed. These biosensors may be used as continuous rapid-warning sentinels for detection of chemical warfare agents in sunlight-exposed drinking water supplies.     

Synthesis and SAR of N-benzoyl-L-biphenylalanine derivatives: discovery of TR-14035, a dual alpha(4)beta(7)/alpha(4)beta(1) integrin antagonist

alpha(4)beta(1) and alpha(4)beta(7) integrins are key regulators of physiologic and pathologic responses in inflammation and autoimmune disease. The effectiveness of anti-integrin antibodies to attenuate a number of inflammatory/immune conditions provides a strong rationale to target integrins for drug development. Important advances have been made in identifying potent and selective candidates, peptides and peptidomimetics, for further development. Herein, we report the discovery of a series of novel N-benzoyl-L-biphenylalanine derivatives that are potent inhibitors of alpha4 integrins. The potency of the initial lead compound (1: IC(50) alpha(4)beta(7)/alpha(4)beta(1)=5/33 microM) was optimized via sequential manipulation of substituents to generate low nM, orally bioavailable dual alpha(4)beta(1)/alpha(4)beta(7) antagonists. The SAR also led to the identification of several subnanomolar antagonists (134, 142, and 143). Compound 81 (TR-14035; IC(50) alpha(4)beta(7)/alpha(4)beta(1)=7/87 nM) has completed Phase I studies in Europe. The synthesis, SAR and biological evaluation of these compounds are described.