A simpler, less expensive technique for delayed primary closure of fasciotomies

A variety of techniques have recently been advanced for delayed primary closure of wounds following emergent fasciotomy for compartment syndrome. We introduce a very simple, effective method for gradual reapproximation of margins using daily reapplication of Steri-strips (3M Surgical Products, St. Paul, Minnesota). This method allows final closure of fasciotomy wounds with simple suture in 5-8 days without scar contractures, marginal necrosis, infection, or significant pain. Moreover, because it requires no specialized equipment and can be applied in skilled nursing centers or at home by trained nurses, this technique could reduce the cost of caring for fasciotomy patients.

Short-term exposure to homocysteine depresses rat aortic contractility by an endothelium-dependent mechanism

The effect of short-term exposure to homocysteine (Hcy) on the contractile characteristics of rat aortic tissue was assessed both in vitro and in vivo. The contractile response of Hcy-treated aortic rings in culture for 1 or 4 days was unchanged from control responses. By comparison, aortic rings from animals injected with Hcy showed marked attenuation of response compared with controls injected with saline, cysteine or methionine. The contractile response to K+ was decreased within 24 hours of Hcy injection, whereas the response to both K+ (-27%) and noradrenaline (-56%) was significantly decreased by 4 days. In contrast, the contractile response to phorbol-12,13-dibutyrate was not different between Hcy and control groups. Intimal rubbing completely restored the responsiveness of Hcy-treated tissue to K+ and noradrenaline. By comparison, L-NAME only partially restored contractile responsiveness, while the cyclooxygenase inhibitor indomethacin had no effect on contractile attenuation induced by Hcy. Western blot analysis showed a 2-fold increase of endothelial nitric oxide synthase (eNOS) and a 3-fold increase in inducible nitric oxide synthase (iNOS) protein expression in the aortic endothelial cells from Hcy-injected rats. The results indicate an early detectable effect of Hcy on the in vivo contractile properties of vascular smooth muscle. The effect is endothelium-mediated and may vary depending on the agonist studied. The mechanism is uncertain but appears to involve increased nitric oxide (NO) production. Finally, the data suggest that attenuation of contraction may not be due to a direct effect of Hcy but that the compound is modified or acts indirectly in vivo.

Short-term exposure to homocysteine depresses rat aortic contractility by an endothelium-dependent mechanism

The effect of short-term exposure to homocysteine (Hcy) on the contractile characteristics of rat aortic tissue was assessed both in vitro and in vivo. The contractile response of Hcy-treated aortic rings in culture for 1 or 4 days was unchanged from control responses. By comparison, aortic rings from animals injected with Hcy showed marked attenuation of response compared with controls injected with saline, cysteine or methionine. The contractile response to K+ was decreased within 24 hours of Hcy injection, whereas the response to both K+ (-27%) and noradrenaline (-56%) was significantly decreased by 4 days. In contrast, the contractile response to phorbol-12,13-dibutyrate was not different between Hcy and control groups. Intimal rubbing completely restored the responsiveness of Hcy-treated tissue to K+ and noradrenaline. By comparison, L-NAME only partially restored contractile responsiveness, while the cyclooxygenase inhibitor indomethacin had no effect on contractile attenuation induced by Hcy. Western blot analysis showed a 2-fold increase of endothelial nitric oxide synthase (eNOS) and a 3-fold increase in inducible nitric oxide synthase (iNOS) protein expression in the aortic endothelial cells from Hcy-injected rats. The results indicate an early detectable effect of Hcy on the in vivo contractile properties of vascular smooth muscle. The effect is endothelium-mediated and may vary depending on the agonist studied. The mechanism is uncertain but appears to involve increased nitric oxide (NO) production. Finally, the data suggest that attenuation of contraction may not be due to a direct effect of Hcy but that the compound is modified or acts indirectly in vivo.Key words: nitric oxide, nitric oxide synthase, in vivo, smooth muscle.

Plasma renin activity as a marker for growth failure due to sodium deficiency in young rats

We evaluated the effect of feeding diets of varying sodium content on growth and plasma renin activity (PRA) in young rats. In the first study, four groups of rats were offered 10 g/100 g body weight per day of diets containing either 0.005%, 0.015%, 0.03%, or 0.3% sodium; weight gain per day of each rat was followed for 10-14 days and PRA was then measured. A control group was fed a sodium-replete tryptophan-deficient diet which caused protein calorie malnutrition and inhibited growth. Weight gain (g/day) among the rats on the sodium-deficient diets varied directly (r = 0.81, P < 0.001) and PRA inversely (r = -0.82, P < 0.001) with dietary sodium content. PRA varied inversely with weight gain (r = -0.84, P < 0.001). Insulin-like growth factor-1 (IGF-1), which is depressed in calorie-deficient growth failure, was depressed in all the rats on the low-sodium intakes relative to ad libitum-fed controls, but did not vary in relation to dietary sodium or weight gain within those groups. In rats fed the tryptophan-deficient diet, both IGF-1 and weight gain were severely depressed; PRA was normal. In the second study, rats in each of two groups were pair fed, the diet containing either 0.03% or 0.3% sodium matched to rats fed the 0.005% sodium diet; weight gain was followed for 28 days. Both length and weight gain were retarded; PRA again varied inversely with dietary sodium content and with weight gain.(ABSTRACT TRUNCATED AT 250 WORDS)

Factors that limit brain volume changes in response to acute and sustained hyper- and hyponatremia

Rats were made acutely hyper- or hyponatremic by infusion of hypertonic saline or water, respectively. Other rats were maintained in these states from 1 to 7 days to observe the effects of time. Brain tissue water, Na, Cl, and K were compared with serum Na and Cl concentration (Na(E) and Cl(E)). The following observations are noted: Brain Cl content varies directly with Cl(E) and brain Na content in the Cl space (Na(e)) varies directly with Na(E), indicating little or no restraint on the inward or outward movement of Na or Cl from the Cl space of brain. The intracellular volume of brain fluid (V(i)) derived as the difference between total water and Cl space, decreases with hypernatremia and increases with hyponatremia. The changes in V(i) in the acute studies are not accompanied by any change in brain K content, or calculated intracellular Na content, and are approximately 0.6 the changes predicted from osmotic behavior of cells, which apply four assumptions: (a) Na(E) is proportional to osmolality; (b) brain osmolality remains equal to plasma osmolality; (c) V(i) is osmotically active; and (d) there is no net gain or loss of solute from V(i). The validity of these assumptions is considered. When changes in osmolality are sustained, V(i) is much closer to control values than when in the acute phase. K content increases in hypernatremia and decreases in hyponatremia. The changes in K content can account for some of the adjustment in V(i) observed over the extended period of hyper- or hyponatremia. The regression of (Na + K)/v upon Na(E) describes a slope less than 1.0 and an intercept of (Na + K)/v equal to 40% of the control (Na + K)/v. These characteristics are interpreted to mean that significant quantities of Na and K in brain are osmotically inactive. The brain protects itself from acute volume changes in response to change in Na(E) by the freedom for Na and Cl to move from the Cl space, by V(i) not changing acutely to the degree predicted from osmotic properties of cells in general, and by significant quantities of Na + K in V(i) being osmotically inactive. With sustained changes in osmolality, V(i) approaches normal values and brain K changes to account for part of this later adjustment.