In situ measurements of nitrate leaching implicate poor nitrogen and irrigation management on sandy soils.

Minimizing the risk of nitrate contamination along the waterways of the U.S. Great Plains is essential to continued irrigated corn production and quality water supplies. The objectives of this study were to quantify nitrate (NO(3)) leaching for irrigated sandy soils (Pratt loamy fine sand [sandy, mixed, mesic Lamellic Haplustalfs]) and to evaluate the effects of N fertilizer and irrigation management strategies on NO(3) leaching in irrigated corn. Two irrigation schedules (1.0x and 1.25x optimum) were combined with six N fertilizer treatments broadcast as NH(4)NO(3) (kg N ha(-1)): 300 and 250 applied pre-plant; 250 applied pre-plant and sidedress; 185 applied pre-plant and sidedress; 125 applied pre-plant and sidedress; and 0. Porous-cup tensiometers and solution samplers were installed in each of the four highest N treatments. Soil solution samples were collected during the 2001 and 2002 growing seasons. Maximum corn grain yield was achieved with 125 or 185 kg N ha(-1), regardless of the irrigation schedule (IS). The 1.25x IS exacerbated the amount of NO(3) leached below the 152-cm depth in the preplant N treatments, with a mean of 146 kg N ha(-1) for the 250 and 300 kg N preplant applications compared with 12 kg N ha(-1) for the same N treatments and 1.0x IS. With 185 kg N ha(-1), the 1.25x IS treatment resulted in 74 kg N ha(-1) leached compared with 10 kg N ha(-1) for the 1.0x IS. Appropriate irrigation scheduling and N fertilizer rates are essential to improving N management practices on these sandy soils.

Facial baroparesis secondary to middle-ear over-pressure: a rare complication of scuba diving.

A facial nerve palsy, as a result of middle-ear high pressure, is a rare complication of sub-aqua diving. It may occur as a result of an acute pressure change in the middle ear during ascent in those patients who have experienced difficulty equalizing their middle-ear pressure during the prior descent. We present the case history of this occurring in a 21-year-old diver and discuss the pathophysiology, management and the previous literature. The correct diagnosis of this condition is important if unnecessary, and potentially hazardous, recompression treatment is to be avoided.

Natural killer gene complex (Nkc) allelic variability in inbred mice: evidence for Nkc haplotypes.

Allelic variability for mouse Chromosome 6 Nkc loci was assessed in 22 common laboratory strains of mice using selected natural killer gene complex (Nkc)-linked sequence tagged site markers. Most Nkc markers distinguished three or more alleles for a particular locus in the assessed mouse strains. Nkc locus alleles were highly conserved among genealogically related inbred strains, whereas far less similarity was observed among unrelated strains. Concurrent strain-to-strain comparisons for all Nkc-linked loci revealed common and uncommon Nkc haplotypes, including some that were likely recombinant. Nkc allele and haplotype assignments in inbred mouse strains and correlation with phenotypic traits should facilitate positional gene cloning strategies for unknown Nkc-linked trait modification loci.

Vital involvement of a natural killer cell activation receptor in resistance to viral infection.

Natural killer (NK) cells are lymphocytes that can be distinguished from T and B cells through their involvement in innate immunity and their lack of rearranged antigen receptors. Although NK cells and their receptors were initially characterized in terms of tumor killing in vitro, we have determined that the NK cell activation receptor, Ly-49H, is critically involved in resistance to murine cytomegalovirus in vivo. Ly-49H requires an immunoreceptor tyrosine-based activation motif (ITAM)-containing transmembrane molecule for expression and signal transduction. Thus, NK cells use receptors functionally resembling ITAM-coupled T and B cell antigen receptors to provide vital innate host defense.

Diagnostic power of lecithin/sphingomyelin ratio and fluorescence polarization assays for respiratory distress syndrome compared by relative operating characteristic curves.

Amniotic fluids from 328 patients were analyzed for lecithin/sphingomyelin (L/S) ratio and surfactant/albumin (S/A) ratio by fluorescence polarization. Of this group, 61 neonates showed respiratory distress syndrome (RDS) on delivery within 3 days of testing. We compared the power of the L/S and S/A in diagnosing pulmonary maturity, using relative operating characteristic (ROC) curves. The area defined by the ROC curve of the S/A test exceeded the area defined by the L/S curve, but this difference was not statistically significant. The diagnostic power of the S/A test appears to be at least equal to that of the standard L/S test. A review of five cases of RDS in which laboratory tests had suggested maturity showed that neither the L/S nor the S/A could satisfactorily resolve the problem of false interpretations of maturity, particularly in mothers with diabetes mellitus who underwent cesarean section.

Deep-venous thrombosis of the upper extremity after traumatic brain injury.

Deep-venous thrombosis (DVT) of the lower extremity occurs frequently in a variety of patients, including those with traumatic brain injury (TBI), during their rehabilitation. Thrombosis of the major veins of the upper extremity is believed to be relatively rare, although it has increased in recent years due to the routine use of indwelling percutaneous central venous catheters. Upper extremity pain and swelling in a TBI patient is commonly attributed to heterotopic ossification, reflex sympathetic dystrophy, or occult fracture. Clinicians may not consider DVT in the differential diagnosis. No longer regarded as a benign disorder, we report the successful outcome in a 27-year-old with TBI who developed an upper extremity DVT after subclavian catheterization. The diagnostic findings, as well as treatment recommendations are reviewed.

Carpal tunnel syndrome secondary to wrist and finger flexor spasticity.

Ten patients with spastic wrist flexion deformities secondary to traumatic brain injury were evaluated for carpal tunnel syndrome. The angle of wrist flexion deformity averaged 75 degrees (range, 58 to 115 degrees). Nerve conduction studies demonstrated prolonged median motor and/or sensory latencies in all patients. Preoperative wick catheter measurements of carpal tunnel pressures in eight patients averaged 11 mm Hg in the resting position, 21 mm Hg in maximal wrist flexion, and 15 mm Hg in maximal extension. Each patient had carpal tunnel release with simultaneous wrist and finger flexor tendon releases or lengthenings. At surgery nine of the median nerves were constricted at the proximal edge of the transverse carpal ligament. The presence of normal carpal tunnel pressures and impingement of the median nerve at the proximal edge of the transverse carpal ligament indicates that the chronically flexed posture of the wrist resulted in median nerve compression, and this condition may be aggravated by underlying pressure from the spastic finger flexors.

Dynamic electromyography to assess elbow spasticity.

Control of elbow motion was evaluated in 45 extremities of adults with spasticity resulting from traumatic brain injury with use of dynamic electromyography. Simultaneous recording of elbow motion was obtained using a double parallelogram goniometer. Thirty-four male and 9 female patients were studied. Mean elbow flexion was 85 degrees and mean extension was 20 degrees. The average time of elbow flexion was 1.8 seconds. Extension time was prolonged to a mean of 4.0 seconds. Dynamic electromyography revealed a consistent pattern of muscle activity. Severe spasticity was noted in the brachioradialis muscle. Moderate spasticity was present in the biceps and only mild spasticity was seen in the brachialis muscle. Normal phasic muscle activity was the rule in the triceps. All patients had active elbow flexion, but the flexor spasticity limited smooth extension. Elbow flexor spasticity, especially of the brachioradialis and biceps muscles, commonly interferes with hand placement. Lengthening of the biceps and brachialis tendons combined with release of the brachioradialis enhances elbow motion and improves hand placement.

The treatment of spastic planovalgus foot deformity in the neurologically impaired adult.

The surgical correction of 14 feet with spastic planovalgus in the neurologically impaired adult is reviewed. Evaluation of the patterns of lower extremity muscle activity preoperatively by dynamic EMG showed overactivity of the peroneus longus. A new gait pattern which has not been previously reported was observed. This "combination foot" deformity, noted in six patients, consists of equinovarus in swing, and planovalgus in stance during the gait cycle. The remaining eight patients exhibited planovalgus in swing and stance. Transfer of the peroneus longus tendon to either the cuboid or navicular was performed in seven (50%) patients. Release of the peroneus longus was performed in four (29%) patients. Two patients had Z-lengthening of the peroneus longus, and tenodesis of the peroneus longus to posterior tibialis was performed in one patient. The mean postoperative follow-up time was 34.6 months. All feet were plantigrade. Ten (71%) feet were balanced. Four (29%) feet were improved. There were no failures or complications. Thirteen patients were able to ambulate independently after surgery and one patient continued to require only stand-by-assistance secondary to balance problems. No patient decreased in ambulation level. Seven (64%) of the 11 patients who required bracing, preoperatively became brace free. Peroneus longus was found to be the major deforming force in spastic planovalgus. Release, transfer, or tenodesis of the peroneus longus is effective in correcting planovalgus.