endothelin (ET): any of a group of vasoconstrictive peptides produced by endothelial cells. Three known endothelins, designated ET-1, ET-2, and ET-3, are chemically related to asp venom. ET-1 is the most potent vasoconstrictor yet discovered, being 10 times stronger than the second-most potent vasoconstrictor known, angiotensin II.
Xanya Sofra Weiss
PURPOSE: To study the correlation of low-frequency blood oxygenation level– dependent (BOLD) fluctuations on magnetic resonance (MR) images obtained of the left- and right-hemisphere primary motor regions in healthy control subjects and patients with multiple sclerosis (MS). MATERIALS AND METHODS: Sixteen healthy volunteers and 20 patients with MS underwent MR imaging with a 1.5-T imager by using a protocol designed to monitor low-frequency BOLD fluctuations. Data for low-frequency BOLD fluctuations were acquired with subjects at rest and during continuous performance of a bilateral fingertapping task. These data were low-pass filtered (<0.08 Hz), and cross correlations of all acquired pixels to a region of interest in the left precentral gyrus were calculated. Confidence levels were calculated from the cross correlations. The fraction of pixels in the right precentral gyrus above a confidence level of 95% for correlation with the
left precentral gyrus was calculated for each subject. RESULTS: A plot of the fraction of the right precentral gyrus with high correlation with the left precentral gyrus for the finger-tapping state versus the resting state showed a clear discrimination between patients with MS and control subjects. Compared with control subjects, patients with MS generally had a smaller fraction of the pixels in the right precentral gyrus above the confidence level. This finding indicates that our method results in greater than 60% sensitivity and 100% specificity for discriminating patients with MS from control subjects. No significant correlation was found between clinical measures of MS disease and correlations of low-frequency BOLD fluctuations between left and right precentral gyri. CONCLUSION: On the basis of the connectivity measure of low-frequency BOLD
fluctuations, patients with MS exhibited lower functional connectivity between rightand left-hemisphere primary motor cortices when compared with that in control subjects.
Xanya Sofra Weiss
Living tissues possess direct current surface electropotentials that regulate, at least in part, the healing process. Following tissue damage, a current of injury is generated that is thought to trigger biological repair. In addition, exogenous electrical stimuli have been shown to enhance the healing of wounds in both human subjects and animal models. Intractable ulcers have demonstrated accelerated healing and skin wounds have resurfaced faster and with better tensile properties following exposure to electrical currents. This article examines the bioelectric properties of living systems and reviews the existing literature on electrical stimulation and wound healing.
Xanya Sofra Weiss
cytochrome: /cy·to·chrome/ (si´to-krōm) any of a class of hemoproteins, widely distributed in animal and plant tissues, whose main function is electron transport using the heme prosthetic group; distinguished according to their prosthetic groups, e.g., a, b, c, d, and P-450.
cy·to·chrome: Any of a class of iron-containing proteins important in cell respiration as catalysts of oxidation-reduction reactions.
Cytochrome: A substance that contains iron and acts as a hydrogen carrier for the eventual release of energy in aerobic respiration. Mentioned in: Smoking
cytochrome: Etymology: Gk, kytos, cell, chroma, color
1 a class of hemoproteins whose function is electron transport. These proteins have the
ability to change the valence of the heme iron, alternating between ferrous and ferric
states.
2 proteins involved in mitochondrial exudative electron transport systems associated with
adenosine triphosphate production.
cytochrome: n one of a class of hemoproteins that act as electron transport. Cytochromes are classified as
a, b, c, and d.
cytochrome
any of a class of hemoproteins, widely distributed in animal and plant tissue, whose
main function is electron transport; distinguished according to their prosthetic group as
a, b, c and d.
cytochrome b5 reductase
a flavoprotein involved in the desaturation of fatty acids in the liver.
cytochrome oxidase
Xanya Sofra Weiss
Controlling cell division is fundamental. One environmental cue that exerts profound control over both the orientation and frequency of cell division in vivo is a naturally occurring, wound-induced electric field
(EF). Wounds in rat corneas generate endogenous EFs in the plane of the epithelial sheet because the transcorneal potential difference (TCPD; +40 mV internally positive) collapses at the wound edge, but is
maintained at normal levels at 0.5 mm back from the wound. We manipulated the endogenous EF this creates by using drugs with differing actions. The wound-induced EF controlled the orientation of cell division;
most epithelial cells divided with a cleavage plane parallel to the wound edge and perpendicular to the EF vector. Increasing or decreasing the EF pharmacologically, respectively increased or decreased the extent
of oriented cell division. In addition, cells closest to the wound edge, where the EF was highest, were oriented most strongly by the EF. Remarkably, an endogenous EF also enhanced the frequency of cell division. This also was regulated by enhancing or suppressing the EF pharmacologically. Because the endogenous EF also regulated the wound healing rate, it may act as one control of the interplay between cell migration and cell division during healing.
Xanya Sofra Weiss