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Communities of plants, biological soil crusts (BSCs), and arbuscular mycorrhizal (AM) fungi are known to influence soil stability individually, but their relative contributions, interactions, and combined effects are not well understood, particularly in arid and semiarid ecosystems. In a landscape-scale field study we quantified plant, BSC, and AM fungal communities at 216 locations along a gradient of soil stability levels in southern Utah, USA. We used multivariate modeling to examine the relative influences of plants, BSCs, and AM fungi on surface and subsurface stability in a semiarid shrubland landscape. Models were found to be congruent with the data and explained 35% of the variation in surface stability and 54% of the variation in subsurface stability. The results support several tentative conclusions. While BSCs, plants, and AM fungi all contribute to surface stability, only plants and AM fungi contribute to subsurface stability. In both surface and subsurface models, the strongest contributions to soil stability are made by biological components of the system. Biological soil crust cover was found to have the strongest direct effect on surface soil stability (0.60; controlling for other factors). Surprisingly, AM fungi appeared to influence surface soil stability (0.37), even though they are not generally considered to exist in the top few millimeters of the soil. In the subsurface model, plant cover appeared to have the strongest direct influence on soil stability (0.42); in both models, results indicate that plant cover influences soil stability both directly (controlling for other factors) and indirectly through influences on other organisms. Soil organic matter was not found to have a direct contribution to surface or subsurface stability in this system. The relative influence of AM fungi on soil stability in these semiarid shrublands was similar to that reported for a mesic tallgrass prairie. Estimates of effects that BSCs, plants, and AM fungi have on soil stability in these models are used to suggest the relative amounts of resources that erosion control practitioners should devote to promoting these communities. This study highlights the need for system approaches in combating erosion, soil degradation, and arid-land desertification.

This study compared the frequency of variant cytochrome P450 2C9 (CYP2C9) alleles and warfarin S/R concentration ratio in patients who required low-dose (<2.5 mg/day) and average-dose (5+/-0.5 mg/day) warfarin. Patients who achieved a therapeutic international normalized ratio were recruited from the Atlanta Veterans Affairs Medical Center anticoagulation clinic. CYP2C9*2 and *3 alleles were determined by validated Taqman allelic discrimination assays. Warfarin S and R concentrations were determined by chiral capillary electrochromatography with electrospray ionization mass spectrometry. At least 1 variant allele was found in 66.7% and 22.2% of patients in the low-dose and average-dose groups, respectively (P= .001, chi(2)). The warfarin S/R concentration ratio was 0.665 (range, 0.162-3.58) and 0.452 (range, 0.159-2.36) for patients receiving low-dose and average-dose therapy, respectively (P= .097). A warfarin requirement of <2.5 mg/day and an elevated warfarin S/R concentration ratio were each associated with a higher frequency of variant CYP2C9 alleles.

The objective of this study was to report 2 cases of CYP2C9 genetic polymorphism and elevated warfarin S:R ratios in patients taking low doses of warfarin, and compare the observed characteristics with those in published reports. Two patients of different age groups and races were evaluated for CYP2C9 genotype and warfarin S:R ratios. The patients had been stabilized on weekly warfarin doses of 10.5 mg and 10 mg, respectively. Each patient was found to have at least 1 variant CYP2C9 allele. Elevated warfarin S:R ratios in both patients provided evidence for impaired metabolism of S-warfarin. This report of a CYP2C9*3 heterozygous individual taking a low dose of warfarin is consistent with previous reports in the literature. This summary of a CYP2C9*6 homozygous individual taking a low dose of warfarin is the first such published report. CYP2C9 genotyping in these patients provided a likely explanation for their continued low warfarin dosage requirements. Awareness of a patient's CYP2C9 genotype may provide an explanation for low warfarin dosage requirements in stable patients and may help in determining the optimal dose in patients being initiated on warfarin.

Stroke is the third leading cause of death in the US with recurrent events a high likelihood in those who survive an initial event. The long-term goal of therapy is to prevent the recurrence of stroke and other atherosclerotic events. Aspirin has been the first-line agent for stroke prevention for a long time. As new antiplatelet agents have been introduced, their role in the secondary prevention of stroke remains to be defined. In particular, the role of the combination of aspirin and modified-release dipyridamole (Aggrenox, Boehringer Ingelheim Corp.), the newest product, in the secondary prevention of stroke, remains unknown. The purpose of this manuscript is to review the evidence of these antiplatelet agents in the secondary prevention of stroke and arrive at a conclusion specifically regarding the role of Aggrenox. Clinical studies which examined stroke as a single primary outcome or as one event in a combined primary outcome will be reviewed.

Objective: To review the chemistry, pharmacology, efficacy, and safety of trivalent chromium in the treatment of type 2 diabetes and hyperlipidemia., Data Sources: The English literature was searched from 1966 through May 2002 using MEDLINE, International Pharmaceutical Abstracts, and EMBASE. The key words included chromium, glucose, lipids, and diabetes. Pertinent references from review articles and studies were used as additional sources., Data Synthesis: Trivalent chromium is an essential nutrient and has a key role in lipid and glucose metabolism. Supplementation with chromium does not appear to reduce glucose levels in euglycemia. It may, however, have some efficacy in reducing glucose levels in hyperglycemia. The effects of chromium on lipid levels are variable. Chromium in doses <1000 microg/d appears to be safe for short-term administration. Kidney function and dermatologic changes need to be monitored., Conclusions: Chromium appears to be a safe supplement and may have a role as adjunctive therapy for treatment of type 2 diabetes. Additional large-scale, long-term, randomized, double-blind studies examining the effect of various doses and forms of chromium are needed.

The role of anticoagulation in the secondary prevention of noncardioembolic stroke has long been an area of debate. Previous evidence has shown that anticoagulation is unsafe at an International Normalized Ratio between 3.0 and 4.5. Results of the recently published Warfarin-Aspirin Recurrent Stroke Study (WARSS) suggest that there is no difference between warfarin and aspirin in the prevention of recurrent ischemic stroke or death or in the rate of major hemorrhage. Differences in the therapeutic interventions used may have had an effect on the differences in endpoints achieved as compared with previous studies. Results of ongoing trials are anticipated to further clarify the role of anticoagulation in the secondary prevention of stroke.