Fibrin fibers have extraordinary extensibility and elasticity

Blood clots perform an essential mechanical task, yet the mechanical behavior of fibrin fibers, which form the structural framework of a clot, is largely unknown. By using combined atomic force-fluorescence microscopy, we determined the elastic limit and extensibility of individual fibers. Fibrin fibers can be strained 180% (2.8-fold extension) without sustaining permanent lengthening, and they can be strained up to 525% (average 330%) before rupturing. This is the largest extensibility observed for protein fibers. The data imply that fibrin monomers must be able to undergo sizeable, reversible structural changes and that deformations in clots can be accommodated by individual fiber stretching.     

Effects of carprofen on renal function and results of serum biochemical and hematologic analyses in anesthetized dogs that had low blood pressure during anesthesia

OBJECTIVE: To investigate effects of IV administered carprofen on indices of renal function and results of serum biochemical and hematologic analyses in dogs anesthetized with acepromazine-thiopentone-isoflurane that had low blood pressure during anesthesia. ANIMALS: 6 healthy Beagles. PROCEDURE: A randomized crossover study was conducted, using the following treatments: saline (0.9% NaCl solution)-saline, saline-carprofen, and carprofen-saline. Saline (0.08 ml/kg) and carprofen (4 mg/kg) were administered IV. The first treatment was administered 30 minutes before induction of anesthesia and immediately before administration of acepromazine (0.1 mg/kg, IM). Anesthesia was induced with thiopentone (25 mg/ml, IV) and maintained with inspired isoflurane (2% in oxygen). The second treatment was administered 30 minutes after onset of inhalation anesthesia. Blood gases, circulation, and ventilation were monitored. Renal function was assessed by glomerular filtration rate (GFR), using scintigraphy, serum biochemical analyses, and urinalysis. Hematologic analysis was performed. Statistical analysis was conducted, using ANOVA or Friedman ANOVA. RESULTS: Values did not differ significantly among the 3 treatments. For all treatments, sedation and anesthesia caused changes in results of serum biochemical and hematologic analyses, a decrease in mean arterial blood pressure to 65 mm Hg, an increase of 115 pmol/L in angiotensin II concentration, and an increase of 100 seconds in time required to reach maximum activity counts during scintigraphy. CONCLUSIONS AND CLINICAL RELEVANCE: Carprofen administered IV before or during anesthesia did not cause detectable significant adverse effects on renal function or results of serum biochemical and hematologic analyses in healthy Beagles with low blood pressure during anesthesia.     

Effect of nitrogen inputs to cereals on nitrate leaching from sandy soils

Abstract. The effect of nitrogen fertilizer inputs to cereal crops on nitrate leaching after harvest was tested on 21 experiments on sandy soils in England. At small nitrogen fertilizer rates leaching increased very little with increasing inputs, while at high rates more than half of any additional nitrogen could be accounted for as increase in nitrate leached. In many cases the response fitted two straight lines. Nitrogen offtake in grain also fitted two straight lines, with a form which complemented the leaching response. The gradient averaged 0.52 kg N in grain for every additional 1kg N applied below the break point, but only 0.05 kg/kg above. The break points were generally close to or above the economic optimum N input. The effect of inputs on leaching could he quantitatively related to nitrogen offtake in grain, assuming a constant ratio of nitrogen in grain to total nitrogen uptake. The results show that fields receiving N inputs in excess of the economic optimum cause a disproportionately large nitrate loss. However because of uncertainty in predicting the break point in advance, modest further reduction in leaching will occur by reducing inputs to somewhat below the expected economic optimum.     

The transfer of methylmercury between ambient air and different lake waters

With the intention to elucidate, at least partly, why lakes situated nearby sometimes exhibit very different concentration of methylmercury in their fish population, two such lakes have been studied. A newly developed bubbling method was applied to determine very low concentrations of airborne methylmercury and the actual distribution constant (air/water). The water in one of the lakes studied was clear. In the other it was brownish. The result of the investigation showed that water in the clearwater lake with respect to the distribution of methylmercury between air and water behaved nearly in the same way as MQ-water. The behaviour of the brownish lakewater was however quite different. It turned out that the bubbling procedure in this case resulted in generation of some methylmercury in this water.     

Uptake and distribution of thiabendazole by seed potatoes

The uptake of thiabendazole into potato seed tubers (cultivar King Edward) was determined by the method of application, more being taken up from solutions and suspensions than from dusts. Penetration and uptake were greatest with solutions at pH 3, and less at higher or lower pHs. The addition of inorganic salts (KCl, CaCl₂) had no effect. Treatment of tubers with weak solutions of mineral acid increased uptake of thiabendazole. There was little movement and no metabolism of the chemical when potatoes were stored for 3 months.