Economic Studies Reinforce Efforts to Safeguard Specialty Crops in the United States.

Pathogen-tested foundation plant stocks are the cornerstone of sustainable specialty crop production. They provide the propagative units that are used to produce clean planting materials, which are essential as the first-line management option of diseases caused by graft-transmissible pathogens such as viruses, viroids, bacteria, and phytoplasmas. In the United States, efforts to produce, maintain, and distribute pathogen-tested propagative material of specialty crops are spearheaded by centers of the National Clean Plant Network (NCPN). Agricultural economists collaborated with plant pathologists, extension educators, specialty crop growers, and regulators to investigate the impacts of select diseases caused by graft-transmissible pathogens and to estimate the return on investments in NCPN centers. Economic studies have proven valuable to the NCPN in (i) incentivizing the use of clean planting material derived from pathogen-tested foundation plant stocks; (ii) documenting benefits of clean plant centers, which can outweigh operating costs by 10:1 to 150:1; (iii) aiding the development of disease management solutions that are not only ecologically driven but also profit maximizing; and (iv) disseminating integrated disease management recommendations that resonate with growers. Together, economic studies have reinforced efforts to safeguard specialty crops in the United States through the production and use of clean planting material.

Construction and characterization of two bacterial artificial chromosome libraries of pea (Pisum sativum L.) for the isolation of economically important genes.

Pea (Pisum sativum L.) has a genome of about 4 Gb that appears to share conserved synteny with model legumes having genomes of 0.2-0.4 Gb despite extensive intergenic expansion. Pea plant inventory (PI) accession 269818 has been used to introgress genetic diversity into the cultivated germplasm pool. The aim here was to develop pea bacterial artificial chromosome (BAC) libraries that would enable the isolation of genes involved in plant disease resistance or control of economically important traits. The BAC libraries encompassed about 3.2 haploid genome equivalents consisting of partially HindIII-digested DNA fragments with a mean size of 105 kb that were inserted in 1 of 2 vectors. The low-copy oriT-based T-DNA vector (pCLD04541) library contained 55 680 clones. The single-copy oriS-based vector (pIndigoBAC-5) library contained 65 280 clones. Colony hybridization of a universal chloroplast probe indicated that about 1% of clones in the libraries were of chloroplast origin. The presence of about 0.1% empty vectors was inferred by white/blue colony plate counts. The usefulness of the libraries was tested by 2 replicated methods. First, high-density filters were probed with low copy number sequences. Second, BAC plate-pool DNA was used successfully to PCR amplify 7 of 9 published pea resistance gene analogs (RGAs) and several other low copy number pea sequences. Individual BAC clones encoding specific sequences were identified. Therefore, the HindIII BAC libraries of pea, based on germplasm accession PI 269818, will be useful for the isolation of genes underlying disease resistance and other economically important traits.

Roentgenographic evaluation of the cervical spine. A selective approach.

BACKGROUND: To determine if routine radiographic evaluation of the cervical spine could be eliminated in the alert, sober trauma patient who has no neck pain, tenderness, or other major injuries without a significant increase in missed occult injury. DESIGN: Prospective cohort study. SETTING: Emergency department and general surgery service at a military tertiary medical center. MAIN OUTCOME MEASURE: Those patients with cervical spine injuries. RESULTS: Sixteen patients (2%) had cervical spine injuries, all had signs and/or symptoms of their injury on presentation. Ninety-six patients (14%) who were not intoxicated and had no neck pain, tenderness, or other major injuries were evaluated. None of these patients had abnormal cervical spine studies. Two hundred ninety patients (43%) were followed up between 30 to 150 days. No missed injuries were noted. CONCLUSIONS: These results indicate that blunt trauma patients may not require cervical spine roentgenography if they meet the following criteria: absence of mental status changes, intoxication, neck pain or tenderness, neurologic signs or symptoms, or simultaneous major distracting injury. Because of the small incidence of cervical spine injuries, further studies are necessary to evaluate the positive predictive value of history and physical examination of the cervical spine in a trauma patient.

Emergency center arteriography.

From 1983 through 1989, 1,882 emergency center arteriograms were performed on 1,802 patients suspected of having peripheral vascular injuries. The most common indication for emergency center arteriography (ECA) was the proximity of an injury to a major vascular structure. This was the only indication in 1,712 injured extremities (91%). There were 1,510 true negative arteriograms, 294 true positives, 7 false negatives, and 14 false positives. Accordingly, the sensitivity was 95.5% and the specificity was 97.7%. The remaining 57 arteriograms were either equivocal or technically inadequate. Further evaluation of these patients uncovered an additional 11 vascular injuries. Operative intervention was required for 196 (64.3%) injuries detected by emergency arteriography. The remaining 109 injuries were considered minor and were not repaired. No complications developed in 91 patients (88%) with minor vascular injuries who were available for a mean follow-up duration of 12 months. One thousand forty-eight patients (69.4%) with negative arteriograms were followed for a mean of 18 months, and no vascular complications were noted. Emergency center arteriography is a rapid, accurate, and cost-effective technique. It is of particular value in detecting the presence of occult arterial injuries when proximity of a major vascular structure is the sole indication for arteriography. When formal arteriographic support is either unavailable or time consuming, ECA is recommended.