Venous outflow of the leg: Anatomy and physiologic mechanism of the plantar venous plexus

AbstractPurpose: Mechanisms of venous outflow from the leg and foot have not been clearly defined. The purpose of this study was to evaluate the anatomy and physiologic mechanism of the plantar venous plexus and its impact on venous drainage from the tibial veins.Methods: Fifty phlebograms that contained complete foot and calf films were reviewed. On lateral films, the number of veins in the plantar venous plexus and its tibial outflow tract were counted. The length and diameter of the longest vein in the plantar venous system and the length of the foot arch were measured. The ratio of the length of the plantar venous plexus to the arch length was calculated. The presence or absence of valves within the plexus was recorded. Plantar venous plexus outflow was evaluated by an duplex ultrasonographic scan of the posterior tibial, anterior tibial, and peroneal veins during intermittent external pneumatic compression of the plantar surface of the foot.Results: The plantar venous plexus was composed of one to four large veins (mean, 2.7 veins) within the plantar aspect of the foot. The diameter of these veins was 4.0 ± 1.2 mm. The veins coursed diagonally from a lateral position in the forefoot to a medial position at the level of the ankle, spanning 75% of the foot arch. Prominent valves were recognized within the plantar veins in 22 of 50 patients. The plexus coalesced into an outflow tract of one to four veins (mean, 2.5 veins) that flowed exclusively into the posterior tibial venous system. Small accessory veins that drained the plantar surface of the forefoot flowed into either the posterior tibial or peroneal veins. This pattern of selective drainage of the plantar venous plexus was confirmed by duplex imaging. Mechanical compression of the plantar venous plexus produced a mean peak velocity in the posterior tibial veins of 123 ± 71 cm/sec, in the anterior tibial veins of 24 ± 14 cm/sec, and in the peroneal veins of 29 ± 26 cm/sec.Conclusions: The plantar venous plexus is composed of multiple large-diameter veins that span the arch of the foot. Compression of the plantar venous plexus, such as that which occurs during ambulation, is capable of significantly increasing flow through the posterior tibial venous system into the popliteal vein. Its function may be integral to venous outflow from the calf and priming of the more proximal calf muscle pump. (J Vasc Surg 1996;24:819-24.

The Origin of the Brightest Cluster Galaxies

Most clusters and groups of galaxies contain a giant elliptical galaxy in their centres which far outshines and outweighs normal ellipticals. The origin of these brightest cluster galaxies is intimately related to the collapse and formation of the cluster. Using an N-body simulation of a cluster of galaxies in a hierarchical cosmological model, we show that galaxy merging naturally produces a massive, central galaxy with surface brightness and velocity dispersion profiles similar to observed BCG's. To enhance the resolution of the simulation, 100 dark halos at $z=2$ are replaced with self-consistent disk+bulge+halo galaxy models following a Tully-Fisher relation using 100000 particles for the 20 largest galaxies and 10000 particles for the remaining ones. This technique allows us to analyze the stellar and dark matter components independently. The central galaxy forms through the merger of several massive galaxies along a filament early in the cluster's history. Galactic cannibalism of smaller galaxies through dynamical friction over a Hubble time only accounts for a small fraction of the accreted mass. The galaxy is a flattened, triaxial object whose long axis aligns with the primordial filament and the long axis of the cluster galaxy distribution agreeing with observed trends for galaxy-cluster alignment.Comment: Revised and accepted in ApJ, 25 pages, 10 figures, online version available at http://www.cita.utoronto.ca/~dubinski/bcg

Dynamics of a semiconductor laser with optical feedback

We investigate both experimentally and theoretically the dynamics of a semiconductor laser with optical feedback in the low-frequency fluctuation regime. First we demonstrate that low-frequency fluctuations can be observed for both single and multimode operation of a semiconductor laser with optical feedback. The analysis of the fast dynamics associated with this low-frequency instability is well described by single-mode rate equations. In the multimode regime, fast pulsation is observed in every laser mode. In this case the fluctuations in total intensity are much smaller than those in the intensity of each individual mode, This indicates the presence of anticorrelations dynamics at high frequency between the different laser modes. (S1050-2947(99)08307-9)

Evaluation of the effectiveness of the Family Nurse Partnership home visiting programme in first time young mothers in Scotland : a protocol for a natural experiment

This project was funded by the Scottish Government Children and Families Directorate [project reference CASE/290185].Peer reviewedPublisher PD

1991: Abilene Christian College Bible Lectures - Full Text

PRAISING GOD: THEMES FROM THE PSALMS Being the Abilene Christian University Annual Bible Lectures 1991 Published by ACU PRESS 1648 Campus Court Abilene, Texas 7960

ACS Observations of a Strongly Lensed Arc in a Field Elliptical

We report the discovery of a strongly lensed arc system around a field elliptical galaxy in Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) images of a parallel field observed during NICMOS observations of the HST Ultra-Deep Field. The ACS parallel data comprise deep imaging in the F435W, F606W, F775W, and F850LP bandpasses. The main arc is at a radius of 1.6 arcsec from the galaxy center and subtends about 120 deg. Spectroscopic follow-up at Magellan Observatory yields a redshift z=0.6174 for the lensing galaxy, and we photometrically estimate z_phot = 2.4\pm0.3 for the arc. We also identify a likely counter-arc at a radius of 0.6 arcsec, which shows structure similar to that seen in the main arc. We model this system and find a good fit to an elliptical isothermal potential of velocity dispersion $\sigma \approx 300$ \kms, the value expected from the fundamental plane, and some external shear. Several other galaxies in the field have colors similar to the lensing galaxy and likely make up a small group.Comment: Accepted for publication in ApJ Letters. 10 pages, 3 figures. Figures have been degraded to meet size limit; a higher resolution version and addtional pictures available at http://acs.pha.jhu.edu/~jpb/UDFparc

Aneurysmal Lesions of Patients with Abdominal Aortic Aneurysm Contain Clonally Expanded T Cells

Abdominal aortic aneurysm (AAA) is a common disease with often life-threatening consequences. This vascular disorder is responsible for 1-2% of all deaths in men aged 65 years or older. Autoimmunity may be responsible for the pathogenesis of AAA. Although it is well documented that infiltrating T cells are essentially always present in AAA lesions, little is known about their role in the initiation and/or progression of the disease. To determine whether T cells infiltrating AAA lesions contain clonally expanded populations of T cells, we amplified beta-chain TCR transcripts by the nonpalindromic adaptor-PCR/Vbeta-specific PCR and/or Vbeta-specific PCR, followed by cloning and sequencing. We report in this article that aortic abdominal aneurysmal lesions from 8 of 10 patients with AAA contained oligoclonal populations of T cells. Multiple identical copies of beta-chain TCR transcripts were identified in these patients. These clonal expansions are statistically significant. These results demonstrate that alphabeta TCR(+) T lymphocytes infiltrating aneurysmal lesions of patients with AAA have undergone proliferation and clonal expansion in vivo at the site of the aneurysmal lesion, in response to unidentified self- or nonself Ags. This evidence supports the hypothesis that AAA is a specific Ag-driven T cell disease