Tracing nitrate transport and environmental impact from intensive swine farming using delta nitrogen-15.

Natural-abundance delta15N showed that nitrate generated from commercial land application of swine (Sus scrofa domesticus) waste within a North Carolina Coastal Plain catchment was being discharged to surface waters by ground water passing beneath the sprayfields and adjacent riparian buffers. This was significant because intensive swine farms in North Carolina are considered non-discharge operations, and riparian buffers with minimum widths of 7.6 m (25 ft) are the primary regulatory control on ground water export of nitrate from these operations. This study shows that such buffers are not always adequate to prevent discharge of concentrated nitrate in ground water from commercial swine farms in the Mid-Atlantic Coastal Plain, and that additional measures are required to ensure non-discharge conditions. The median delta15N-total N of liquids in site swine waste lagoons was +15.4 +/- 0.2% vs. atmospheric nitrogen. The median delta15N-NO3 values of shallow ground water beneath and adjacent to site sprayfields, a stream draining sprayfields, and waters up to 1.5 km downstream were + 15.3 +/- 0.2 to + 15.4 +/- 0.2%. Seasonal and spatial isotopic variations in lagoons and well waters were greatly homogenized during ground water transport and discharge to streams. Neither denitrification nor losses of ammonia during spraying significantly altered the bulk ground water delta15N signal being delivered to streams. The lagoons were sources of chloride and potassium enrichment, and shallow ground water showed strong correlation between nitrate N, potassium, and chloride. The 15N-enriched nitrate in ground water beneath swine waste sprayfields can thus be successfully traced during transport and discharge into nearby surface waters.

A contemporary analysis of medicolegal concerns for physician assistants and nurse practitioners.

The utilization of-PAs and NPs to expand the supply of traditional physician services to the public, at reduced costs, as proposed by President Nixon in 1971, has in 1994 become a national mandate. There is an increasing demand for the "traditional" physician services, which can be efficiently and cost effectively performed by nonphysician practitioners, such as PAs and NPs. Statutory changes permitting physicians "to delegate medical acts in an innovative manner" have been, at times, agonizingly slow. However, when compared to the NP statutes, the PA statutes have evolved at a rapid rate. It is postulated that this may be due to the fact that PAs who are totally dependent on physician supervision are more controllable and hence more acceptable to organized medicine than NPs who are currently flexing their political muscles in a quest for greater independence in their performance of traditional physician services. The reimbursability of the two professions is yet another important consideration. Nurse practitioners are "directly" reimbursed by third-party payors, such as Medicare and Medicade, for the traditional physician services they perform, while PA third-party reimbursement is, by law, paid directly to the employing physician or medical facility. Unlike NPs, PAs were conceived by organized medicine, the AMA, to provide a mechanism for physicians to expand their capability to treat increasing numbers of patients. Accordingly, PAs are tied to their supervising physician by the same governmental agencies that regulate physician licensure. Conversely, NPs, who derive their authority to practice from the various state nurse practice acts, have been, at times, impeded in their quest for an enlargement of their scope of practice, including independent prescriptive privileges. The NP bid for greater independence and enlargement of their scope of practice, on a national level, is viewed by organized medicine as an encroachment into the "independent" practice of medicine under the guise of providing advanced nursing care. Unlike PAs, whose professional existence depends on the supervision of a licensed physician, NPs are, by and large, independent of physician control by virtue of their status as licensed members of the nursing profession. While PAs and NPs were once thought to be virtually interchangeable, the divergence of the two professions over the past two decades has been such that all similarities have, for all intents and purposes, disappeared.(ABSTRACT TRUNCATED AT 400 WORDS)

Riparian Wetlands and Water Quality.

Because of wet soils adjacent to the streams, riparian buffers are frequently present between farming and urban activities on the uplands and small streams. These riparian areas have been shown to be very valuable for the removal of nonpoint-source pollution from drainage water. Several researchers have measured >90% reductions in sediment and nitrate concentrations in water flowing through the riparian areas. The riparian buffers are less effective for P removal but may retain 50% of the surface-water P entering them. I consider riparian buffers to be the most important factor influencing nonpoint-source pollutants entering surface water in many areas of the USA and the most important wetlands for surface water quality protection.

Clinical skills problems. A valid instrument for assessing competence?

Physician assistants are required to take the clinical skills problems (CSP) portion of the National Certifying Examination administered by the National Commission on Certification of Physician's Assistants (NCCPA). No comparable section exists in entry-level physician certification examinations because studies have shown that this type of examination is neither a valid nor a reliable indicator of clinical competence. A published account of the studies used to implement the CSP portion of the National Certifying Examination contained serious flaws, calling the research into question. Denial of certification based solely on failure on the CSP portion of the National Certifying Examination could be challenged legally. The CSP is invalid and unreliable, and should be eliminated.

Prevention of glomerulonephritis and prolonged survival in New Zealand Black/New Zealand White F1 hybrid mice fed an essential fatty acid-deficient diet.

Female B/W mice spontaneously develop an autoimmune disease that is similar to systemic lupus erythematosus. Antibodies to doublestranded DNA (dsDNA) and antinuclear antibodies develop in aging animals; death from immune complex-mediated glomerulonephritis occurs from 8 to 12 mo of age. It has been reported that prostaglandin (PG)E(1) treatment of such mice prolongs survival. In the present study, four groups of female B/W mice were studied beginning at 6-11 wk of age on the following regimens: (a) a synthetic diet that contained 20% safflower oil, (b) a standard laboratory chow diet, (c) a standard diet together with injections of PGE(1), and (d) an essential fatty acid-deficient synthetic diet that contained 20% coconut oil. All animals were tested monthly for antinuclear antibodies and anti-dsDNA. Kidney tissue was obtained for light and immunofluorescence microscopy when animals were dying. All disease manifestations were altered strikingly in the essential fatty acid (EFA)-deficient animals. Intermediate benefit was seen in PGE(1)-treated animals. 7% of the control animals and 18% of safflower oil-fed animals survived to 10 mo. In contrast, the PGE(1)-treated and EFA-deficient mice had a similar survival rate (78-88%). At age 16 mo, 78% of EFA-deficient mice and 45% of PGE(1)-treated mice were alive. 25% of the PGE(1)-treated and 55% of the EFA-deficient animals survived to 20 mo. Serum anti-dsDNA appeared at age 5 mo in safflower oil-fed and control animals, but not until 9 and 12 mo for PGE(1)-treated and EFA-deficient animals, respectively. All kidneys from 7- to 9-mo-old safflower oil-fed and control animals and the majority of kidneys from PGE(1)-treated animals were abnormal by light and immunofluorescence microscopy. Kidneys from EFA-deficient animals were essentially normal at 10 mo. At 13 mo, all PGE(1)-treated animals examined had significant kidney involvement, whereas none of the EFA-deficient animals had glomerulonephritis. These findings demonstrate that an EFA-deficient diet has a beneficial effect on murine lupus erythematosus.