INFLUENCE OF EXPERIMENTAL DIABETES ON THE MICROCIRCULATION OF INJURED PERIPHERAL NERVE - FUNCTIONAL AND MORPHOLOGICAL ASPECTS

Regeneration of diabetic axons has delays in onset, rate and maturation. It is possible that microangiopathy of vasa nervorum, the vascular supply of the peripheral nerve, may render an unfavorable local environment for nerve regeneration. We examined local nerve blood flow proximal and distal to sciatic nerve transection in rats with long-term (8 month) experimental streptozotocin diabetes using laser Doppler flowmetry and microelectrode hydrogen clearance polarography. We then correlated these findings, using in vivo perfusion of an India ink preparation, by outlining the lumens of microvessels from unfixed nerve sections. There were no differences in baseline nerve blood flow between diabetic and nondiabetic uninjured nerves, and vessel number, density, and area were unaltered. After transection, there were greater rises in blood flow in proximal stumps of nondiabetic nerves than in diabetic animals associated with a higher number, density, and caliber of epineurial vessels. Hyperemia also developed in distal stumps of nondiabetic nerves but did not develop in diabetic nerves. In these stumps, diabetic rats had reduced vessel numbers and smaller mean endoneurial vessel areas. Failed or delayed upregulation of nerve blood flow after peripheral nerve injury in diabetes may create a relatively ischemic regenerative microenvironment.     

Hormonal effects on cell proliferation in a human erythroleukemia cell line (K562)

We have investigated the hormonal responsiveness of K562 cells using a serum-substituted in vitro clonogenic assay. Dexamethasone inhibited colony formation by the K562 cells, and the inhibitory effect could be reversed by progesterone (10(-6) M). Fluoxymesterone caused a prominent enhancement of K562 colony growth, whereas estriol had no effect. Stimulation by triiodothyronine was maximal at 10(-7) M, and the thyroid effect could be abrogated by the beta 2-adrenergic antagonist butoxamine in equimolar concentrations. Using standard tissue culture conditions, the beta-adrenergic agent isoproterenol, but not the alpha catecholamine phenylephrine, enhanced the proliferation of K562 cells. When K562 cells were grown under hormone-depleted conditions, they developed responsiveness to phenylephrine and were no longer stimulated by isoproterenol. DbcAMP and prostaglandins of the E series also caused K562 colony enhancement. Prostaglandin F2 alpha had no effect on cell proliferation. Insulin was an effective stimulant of colony formation of K562 cells, as were human growth hormone and ovine prolacin. Bovine growth hormone had no effect. Our results are consistent with the identificaiton of K562 as an erythroid line, and they indicate that K562 cells respond to endocrine hormones in a manner analogous to normal erythroid progenitors.     

Adherence of L1210 murine leukemia cells to sephacryl- aminopropylcobalamin beads treated with transcobalamin-II

Sephacryl beads containing an immobilized aminopropylcobalamin- transcobalamin-II complex serve as foci for the adherence of L1210 murine leukemia cells. Bead-cell interaction does not occur when (A) nonderivatized beads are used; (B) transcobalamin-II is omitted or presaturated with cyanocobalamin in the preparation of the bead complex; (C) intrinsic factor replaces transcobalamin-II; and (D) the complex is removed from beads by photolysis. These observations suggest that adherence results from the ability of transcobalamin-II to form a bridge between immobilized cobalamin on the bead and receptors in the plasma membrane of the cell.     

More accurate Talairach coordinates for neuroimaging using non-linear registration

While the Talairach atlas remains the most commonly used system for reporting coordinates in neuroimaging studies, the absence of an actual 3-D image of the original brain used in its construction has severely limited the ability of researchers to automatically map locations from 3-D anatomical MRI images to the atlas. Previous work in this area attempted to circumvent this problem by constructing approximate linear and piecewise-linear mappings between standard brain templates (e.g. the MNI template) and Talairach space. These methods are limited in that they can only account for differences in overall brain size and orientation but cannot correct for the actual shape differences between the MNI template and the Talairach brain. In this paper we describe our work to digitize the Talairach atlas and generate a non-linear mapping between the Talairach atlas and the MNI template that attempts to compensate for the actual differences in shape between the two, resulting in more accurate coordinate transformations. We present examples in this paper and note that the method is available freely online as a Java applet.     

Blastomycosis in a young African man presenting with a pleural effusion

Blastomyces dermatitidis is a dimorphic fungus endemic to northwestern Ontario, Manitoba and some parts of the United States. The fungus is also endemic to parts of Africa. Pulmonary and extrapulmonary findings of a 24-year-old African man who presented with weight loss, dry cough and chronic pneumonia not resolving with antibiotic treatment are presented. The unusual occurrence of pulmonary blastomycosis associated with skin lesions and a moderate pleural effusion is reported.     

MEASUREMENTS OF INTERFACE PRESSURE BETWEEN BODY SITES AND THE SURFACES OF FOUR SPECIALISED AIR MATTRESSES

SUMMARY Four specialised air mattresses had interface pressure measured under six body sites prone to pressure sores in 10 subjects, supine and sitting. The mattresses were the Clinirest (SSI) and FirstStep (KCI) continuous airflow mattress overlays, and Airwave (Pegasus) and Nimbus (Huntleigh) alternating pressure air mattresses. On the mattress overlays, average supine interface pressures were 2.33 kPa (scapula), 4.15 kPa (elbow), 1.94 kPa (sacrum) and 2.79 kPa (buttock), although they were higher at the occiput (7.97 kPa) and heel (11.7 kPa). The alternating pressure air mattresses had an average minimum interface pressure close to zero for three sites, rising to 4.28 kPa under the heel. Average maximum interface pressures were 8.61 kPa (occiput), 5.21 kPa (scapula), 4.90 (elbow), 4.85 kPa (sacrum), 4.61 kPa (buttock) and 13.2 kPa (heel). No accepted scientific method exists for comparing the two types of mattress. Our data suggest a clinical benefit at the occiput and heel (supine) in using an alternating pressure air mattress and a benefit in using a continuous airflow mattress overlay at other sites.     

The cerebellum's role in reading: a functional MR imaging study

BACKGROUND AND PURPOSE: Long considered to have a role limited largely to motor-related functions, the cerebellum has recently been implicated as being involved in both perceptual and cognitive processes. Our purpose was to determine whether cerebellar activation occurs during cognitive tasks that differentially engage the component processes of word identification in reading. METHODS: Forty-two neurologically normal adults underwent functional MR imaging of the cerebellum with a gradient-echo echo-planar technique while performing tasks designed to study the cognitive processing used in reading. A standard levels-of-processing paradigm was used. Participants were asked to determine whether pairs of words were written in the same case (orthographic processing), whether pairs of words and non-words rhymed with each other, respectively (phonologic assembly), and whether pairs of words belonged to the same category (semantic processing). Composite maps were generated from a general linear model based on a randomization of statistical parametric maps. RESULTS: During phonologic assembly, cerebellar activation was observed in the middle and posterior aspects of the posterior superior fissure and adjacent simple lobule and semilunar lobule bilaterally and in posterior aspects of the simple lobule, superior semilunar lobule, and inferior semilunar lobule bilaterally. Semantic processing, however, resulted in activation in the deep nuclear region on the right and in the inferior vermis, in addition to posterior areas active in phonologic assembly, including the simple, superior semilunar, and inferior semilunar lobules. CONCLUSION: The cerebellum is engaged during reading and differentially activates in response to phonologic and semantic tasks. These results indicate that the cerebellum contributes to the cognitive processes integral to reading.