Using a probabilistic approach to derive a two-phase model of flow-induced cell migration.

Interstitial fluid flow is a feature of many solid tumors. In vitro experiments have shown that such fluid flow can direct tumor cell movement upstream or downstream depending on the balance between the competing mechanisms of tensotaxis (cell migration up stress gradients) and autologous chemotaxis (downstream cell movement in response to flow-induced gradients of self-secreted chemoattractants). In this work we develop a probabilistic-continuum, two-phase model for cell migration in response to interstitial flow.

Structural Features of Microvascular Networks Trigger Blood Flow Oscillations.

We analyse mathematical models in order to understand how microstructural features of vascular networks may affect blood flow dynamics, and to identify particular characteristics that promote the onset of self-sustained oscillations. By focusing on a simple three-node motif, we predict that network "redundancy", in the form of a redundant vessel connecting two main flow-branches, together with differences in haemodynamic resistance in the branches, can promote the emergence of oscillatory dynamics. We use existing mathematical descriptions for blood rheology and haematocrit splitting at vessel branch-points to construct our flow model; we combine numerical simulations and stability analysis to study the dynamics of the three-node network and its relation to the system's multiple steady-state solutions.

Outbreaks of Invasive Kingella kingae Infections in Closed Communities.

Objectives: To describe the results of the epidemiologic investigation of outbreaks of invasive Kingella kingae infections among attendees at daycare facilities located in 4 closed communities in Israel.

Study Design: The preschool-aged population of communities with clusters of Kingella cases had oropharyngeal cultures performed. K kingae isolates from infected patients and healthy contacts were genotyped by pulsed field gel electrophoresis to determine the spread of outbreak strains.

Transformation of fetal secondary cartilage into embryonic bone in organ cultures of human mandibular condyles.

Mandibular condyles of human fetuses, 14-21 weeks in utero, were kept in an organ culture system for up to 60 days. After 6 days in culture, the cartilage of the mandibular condyle appeared to have maintained its inherent structural characteristics, including all its various layers: chondroprogenitor, chondroblastic, and hypertrophic. After 12 days in culture, no chondroblasts could be seen; instead, the entire cartilage was occupied by hypertrophic chondrocytes.

Structural characterization of the mandibular condyle in human fetuses: light and electron microscopy studies.

Mandibular condyles from 18- to 20-week-old human fetuses were examined in the light and electron microscope with particular attention to intratissue organization and extracellular matrix. In the human fetus the condyle has been divided into five layers: (1) the most superficial, articular layer, (2) chondroprogenitor cell layer, (3) condroblast cell layer, (4) nonmineralized hypertrophic cell layer, and (5) mineralized hypertrophic cell layer. The articular layer is rich in collagen fibers (mostly of the type I collagen), but the cells seldom divide.

Immunohistochemical studies of the extracellular matrix in the condylar cartilage of the human fetal mandible: collagens and noncollagenous proteins.

This study provides data concerning the cells and their extracellular matrix in prenatal human mandibular condylar cartilage. The latter cartilage represents a secondary type of cartilage since it develops late in the morphogenesis of the craniofacial skeleton. The cartilage of the mandibular condyle is actively involved in endochondral ossification, thus showing all the phases of cartilage growth, maturation, and mineralization that precedes de novo bone formation.