Mineralization of Normal and Rachitic Chick Growth Cartilage: Vascular Canals, Cartilage Calcification and Osteogenesis

This paper reviews recent work in the authors\u27 laboratories that has led to new observations and thoughts concerning the mineralization of normal and rachitic chick growth cartilage. The proximal tibial growth cartilages of normal and rachitic chicks were rapidly frozen and prepared for SEM and biochemical studies. Using a scanning microfluorimetric technique we showed that at the mineralization front of normal and rachitic cartilage there is an abrupt change in chondrocyte metabolism. Thus cells in this region exhibited an increase in NADH and oxidative metabolism. In rickets, there was a decrease in the reduced pyridine nucleotide content of each of the zones. The reversal in chondrocyte metabolism was not due to low oxygen tension. SEM observations indicated that this region of cartilage was well supplied with vascular channels; moreover, mineral was first seen deposited in matrix in close proximity to the blood supply. Indeed these vascular channels appeared to be a basic architectural feature of normal cartilage, although disorganized in the rachitic state. The morphological studies also showed that gaps existed in the continuity of the mineral phase in normal cartilage. Although the rachitic cartilage does mineralize, discontinuities in the mineral distribution are much more severe, with the general failure of fusion of adjacent mineral clusters. These structures would serve as pathways for transport of nutritional factors and gases to chondrocytes that are distant from the vascular channels. Observation of hypertrophic eel ls reinforced the view that some osteoblasts represented a terminal stage in the maturation of chondrocytes

Interacting photon-baryon fluid, warm dark matter and the first acoustic peak

The Reduced Relativistic Gas (RRG) model was introduced by A. Sakharov in 1965 for deriving the cosmic microwave background (CMB) spectrum. It was recently reinvented by some of us to achieve an interpolation between the radiation and dust epochs in the evolution of the Universe. This model circumvents the complicated structure of the Boltzmann-Einstein system of equations and admits a transparent description of warm-dark-matter effects. It is extended here to include, on a phenomenological basis, an out-of-equilibrium interaction between radiation and baryons which is supposed to account for relevant aspects of pre-recombination physics in a simplified manner. Furthermore, we use the tight-coupling approximation to explore the influence of both this interaction and of the RRG warmness parameter on the anisotropy spectrum of the CMB. The predictions of the model are very similar to those of the {\Lambda}CDM model if both the interaction and the dark-matter warmness parameters are of the order of $10^{-4}$ or smaller. As far as the warmness parameter is concerned, this is in good agreement with previous estimations on the basis of results from structure formation.Comment: 10 pages and 4 figure

Blue Sky Law and Practice: An Overview

The securities law and regulations in effect from state to state can best be described as diverse. Compliance with these provisions requires a methodical approach involving detailed planning and control. As a practical guide to attorneys, the authors discuss the principal aspects of offering, selling and distributing securities

Stimulation of κ Light-Chain Gene Rearrangement by the Immunoglobulin, µ Heavy Chain in a Pre-B-Cell Line

B-lymphocyte development exhibits a characteristic order of immunoglobulin gene rearrangements. Previous work has led to the hypothesis that expression of the immunoglobulin µ heavy chain induces rearrangement activity at the K light-chain locus. To examine this issue in more detail, we isolated five matched pairs of µ^- and endogenously rearranged µ^+ cell lines from the Abelson murine leukemia virus-transformed pro-B-cell line K.40. In four of the five µ^+ cell lines, substantial expression of µ protein on the cell surface was observed, and this correlated with an enhanced frequency of K immunoglobulin gene rearrangement compared with that in the matched µ^- cell lines. This increased K gene rearrangement frequency was not due to a general increase in the amount of V(D)J recombinase activity in the µ^+ cells. Consistently, introduction of a functionally rearranged µ gene into one of the µ^- pre-B-cell lines resulted in a fivefold increase in K gene rearrangements. In three of the four clonally matched pairs with increased K gene rearrangements, the increase in rearrangement frequency was not accompanied by a significant increase in germ line transcripts from the C_K locus. However, in the fourth pair, K.40D, we observed an increase in germ line transcription of the kappa locus after expression of µ protein encoded by either an endogenously rearranged or a transfected functional heavy-chain allele. In these cells, the amount of the germ line C_K transcript correlated with the measured frequency of rearranged K genes. These results support a regulated model of B-cell development in which µ protein expression in some way targets the V(D)J recombinase to the K gene locus

Quantum corrections to gravity and their implications for cosmology and astrophysics

The quantum contributions to the gravitational action are relatively easy to calculate in the higher derivative sector of the theory. However, the applications to the post-inflationary cosmology and astrophysics require the corrections to the Einstein-Hilbert action and to the cosmological constant, and those we can not derive yet in a consistent and safe way. At the same time, if we assume that these quantum terms are covariant and that they have relevant magnitude, their functional form can be defined up to a single free parameter, which can be defined on the phenomenological basis. It turns out that the quantum correction may lead, in principle, to surprisingly strong and interesting effects in astrophysics and cosmology.Comment: 15 pages, LaTeX, WS style, contribution to the Proceedings of the QFEXT-2011 conference in the Centro de Ciencias de Benasque Pedro Pasqual, Spai

Critical collapse of collisionless matter - a numerical investigation

In recent years the threshold of black hole formation in spherically symmetric gravitational collapse has been studied for a variety of matter models. In this paper the corresponding issue is investigated for a matter model significantly different from those considered so far in this context. We study the transition from dispersion to black hole formation in the collapse of collisionless matter when the initial data is scaled. This is done by means of a numerical code similar to those commonly used in plasma physics. The result is that for the initial data for which the solutions were computed, most of the matter falls into the black hole whenever a black hole is formed. This results in a discontinuity in the mass of the black hole at the onset of black hole formation.Comment: 22 pages, LaTeX, 7 figures (ps-files, automatically included using psfig

The White Nipple Sign: Please Do Not Disturb

Blood spurting or oozing from a varix confirms the diagnosis of variceal hemorrhage. In most cases of variceal hemorrhage, however, the bleeding has ceased by the time endoscopy is performed. Endoscopists rely on identification of stigmata of recent hemorrhage to determine whether varices are the cause of bleeding and to predict the likelihood of rebleeding. Most of the attention has focused on red color signs, such as red wale markings, described by Beppu et al. [Gastrointest Endosc 1981;27:213-218] and well known to endoscopists. Here we describe our experience with a less recognized stigma of variceal hemorrhage known as the ‘white nipple sign’, which resulted in active hemorrhage when manipulated

Psychological and Environmental Correlates of HPA Axis Functioning in Parentally Bereaved Children: Preliminary Findings

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97514/1/jts21788.pd