Effects of microelements on soil nematode assemblages seven years after contaminating an agricultural field.

Long-term effects of Cd, Cr, Cu, Se and Zn were studied 7 years after artificially contaminating plots of an agricultural field on a calcareous chernozem soil. Effects of three to four different contamination levels (originally 10, 30, 90 and 270 mg kg(-1)) were studied. Nematode density was significantly reduced by 90 and 270 mg kg(-1) Se as well as by 270 mg kg(-1) Cr, while 90 and 270 mg kg(-1) Se also reduced nematode generic richness. Maturity Index values (calculated for c-p 2-5 nematodes) consistently decreased with increasing Cr and Se concentration and to a lesser extent in Zn plots as well. Structure Index showed decreasing trends in increasing Cr, Se and (to a lesser extent) in Zn treatments, while in Cd it shows a moderate increase. Distribution of c-p groups was negatively affected by the increasing Cr and Se concentration, while in Zn plots, this decrease was not significant. Response of feeding groups to pollutions was similar to other parameters: Cr and Se caused significant changes toward the loss of variability. The proportion of the most sensitive omnivorous and predatory nematodes decreased clearly as a consequence of Cr and Se treatments. Zn pollution also resulted in a slight decrease in this group, while Cd caused an increase. Nematode diversity profiles showed a significant decrease in the plots of increased Cr and Se concentrations, while increased concentrations of Cu and Zn resulted in ambiguous effects. Besides providing evidence on the harmful effects of Cr and Se on a soil nematode assemblage, our results suggest that simultaneous analysis of Maturity Index, Structure Index and diversity profiles provide a promising tool in nematological indication of soil pollution.

Oxygen debt criteria quantify the effectiveness of early partial resuscitation after hypovolemic hemorrhagic shock.

BACKGROUND: The effectiveness of partial resuscitation after hypovolemic hemorrhagic shock with deferment of full resuscitation is critical to successful hypotensive resuscitation. METHODS: To quantitatively address this issue, 40 canines were bled under anesthesia to a mean oxygen debt (O(2)D) of 104 +/- 7.6 mL/kg over 60 minutes (mortality, 40%). Animals surviving the shock were then immediately resuscitated with 0%, 8.4%, 15%, 30%, or 120% (full resuscitation) of shed volume as 5% albumin and held for 2 hours postshock, when the remaining portion of full resuscitation volume was given. Animals were followed for 7 days postshock with hepatic and renal function studies, and then, under anesthesia, cardiac output and organ biopsy specimens were taken before the animals were killed. RESULTS: By 2 hours postshock, 0% immediate resuscitation had an O(2)D increase of 80 mL/kg above end of shock, but O(2)D at 8.4% immediate resuscitation decreased -30 mL/kg, 15% immediate resuscitation fell -65 mL/kg, 30% immediate resuscitation decreased -80 mL/kg below end of shock, and O(2)D with 120% full resuscitation fell to preshock levels. All decreases in O(2)D were significantly (p < 0.05) below end of shock, but both 15% and 30% immediate resuscitation exceeded the 8.4% immediate resuscitation rate (p < 0.05) throughout the resuscitation, and 120% full resuscitation exceeded these (p < 0.05). The immediate resuscitation O(2)D response correlated significantly (p < 0.001) with base deficit and lactate, but blood pressure was not a significant discriminator. Seven-day biopsies showed return of bowel mucosa but a pattern of cellular injury in heart, liver, and kidney that improved from 8.4% < 15% < 30 < 120% immediate resuscitation. CONCLUSION: The data suggest that, compared with 120% postshock immediate resuscitation, 8.4% and 15% immediate resuscitation give poorer results, with 30% immediate resuscitation showing mild, transient, but acceptable changes in organ function allowing for a 2-hour delay until full resuscitation, with complete 7-day recovery. Base deficit and lactate, but not blood pressure, are significant indices of O(2)D.