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Biomedical subjects

R L Pearson

Publications and source records attributed to R L Pearson.

At least 19 recordsLinked to original sources
PubMed2000

Distance-weighted traffic density in proximity to a home is a risk factor for leukemia and other childhood cancers.

Occupational exposure to elevated concentrations of benzene is a known cause of leukemia in adults. Concentrations of benzene from motor vehicle exhaust could be elevated along highly trafficked streets. Several studies have reported significant associations between proximity to highly trafficked streets and the occurrence of childhood cancers and childhood leukemia. These associations may be due to chronic exposure to benzene or other carcinogenic components of vehicle exhaust from these nearby streets or to some other factor (e.g., noise, increased light exposure, or some unaccounted--for socioeconomic variable). We used data for homes studied in an earlier childhood cancer study conducted in Denver, CO, in the 1980s. No air pollution measurements were made in the original study. We identified the highest trafficked street near each study home and obtained the traffic density in 1979 and 1990. Traffic density was weighted for the distance from the street to the home using 3 different widths of Gaussian curves to approximate the decay of the emissions into the surrounding neighborhoods. The associations between the 750-ft-wide distance-weighted traffic density metrics and all childhood cancers and childhood leukemia are strongest in the highest traffic density category (> or = 20,000 vehicles per day [VPD]). The odds ratio is 5.90 (95% confidence interval [CI] 1.69-20.56) for all cancers and 8.28 (95% CI 2.09-32.80) for leukemia. The results are suggestive of an association between proximal high traffic streets with traffic counts > or = 20,000 VPD and childhood cancer, including leukemia.

Adult↗
PubMed2000

Description of a new computer wire coding method and its application to evaluate potential control selection bias in the Savitz et al. childhood cancer study.

We developed a new computer wire coding method and then applied it to investigate the suggestion that control selection bias might explain the observed association between wire codes and childhood cancer made in the study conducted by Savitz et al. in the Denver area. The computer wire coding method used a geographic information system approach with data on the local distribution electric system and from tax assessor records. Individual residences were represented as a circle scaled to the ground floor area of the residence and centered on the lot centroid. The wire code of the residence was determined from the distance between the circle and the relevant power line, and from the current carrying capacity of that line. Using this method, wire codes were generated for 238 290 residences built before 1986, the time of the Savitz et al. study, in the Denver metropolitan area. We then attempted to reconstruct the 1985 population of hypothetically eligible control children in the Denver metropolitan area by using 1980 census data. Since data were not available to locate the children in each residence within a census block, uniform, Poisson, and negative binomial distributions were used to randomly assign children to residences. To evaluate the likelihood of the wire code distribution of the controls selected by Savitz et al., 100 random trials were conducted for each distribution, matching two controls to each case. The odds ratios between childhood cancer and very high current configuration (VHCC) wire codes were reduced when the assigned controls were used, suggesting control selection bias may have been present. However, control selection bias is unlikely to account for all the reported association between childhood cancer and wire codes in the Savitz et al. study.

Bias↗
PubMed1992

Treatment of acutely infected arthroplasties with incision, drainage, and local antibiotics delivered via an implantable pump.

Twelve patients with acutely (symptomatic less than ten weeks) infected arthroplasties were treated with minimal debridement and intraarticular antibiotic, amikacin, delivered via an implantable pump. The infection was suppressed in ten cases. Intraarticular levels of amikacin were obtained in eight cases. These levels ranged from greater than 150 micrograms/ml to 1688 micrograms/ml. The systemic level of amikacin remained below 10 micrograms/ml in all but one case. Duration of hospitalization averaged 19 days. There were no significant toxic side effects to amikacin.

Acute Disease↗
PubMed1991

Local antibiotic delivery in the treatment of bone and joint infections.

Antibiotics can be delivered locally via an implantable pump to treat bone and joint infections. This is a completely closed system, and the pump is refilled percutaneously at intervals based on its flow rate. The use of this method is described in three specific clinical situations: (1) resistant osteomyelitis (patients with persistent infections despite previous therapy), (2) acutely infected arthroplasties (symptomatic for less than six weeks), and (3) chronically infected arthroplasties (patients infected more than six weeks). In all three clinical situations, hospitalization time was shortened, and high local and low systemic levels of antibiotic were obtained. There was only one incident of side effects to the antibiotic used. This method has been successful in obtaining long-term suppression of infection in 30 of 42 patients with resistant osteomyelitis, 30 of 37 patients with acutely infected arthroplasties, and seven of ten patients with chronically infected arthroplasties. The complication unique to this method of therapy is pump-site and catheter-site infections. This occurred in three patients with recalcitrant osteomyelitis and three patients with acutely infected arthroplasties.

Acute Disease↗
PubMed1991

Accuracy of cultures of material from swabbing of the superficial aspect of the wound and needle biopsy in the preoperative assessment of osteomyelitis.

The pathogens that were identified on cultures of material obtained by swabbing of the superficial aspect of the wound and needle biopsy were compared with those that were isolated from material that was obtained at débridement from sixty patients who had post-traumatic or postoperative osteomyelitis. The cultures of material that was obtained by superficial swabbing of the wound and needle biopsy were inadequate for prediction of the presence of aerobic organisms. Moreover, the failure to isolate anaerobes from the material obtained by needle biopsy did not rule out the presence of anaerobic organisms. Therefore, tissue for culture of aerobic and anaerobic organisms must be obtained during operative débridement in order to identify all pathogenic organisms. Fungi were isolated from the material obtained by biopsy in two patients. In addition, histological examination of the tissue obtained at biopsy led to the diagnosis of epidermoid carcinoma in two patients in whom this diagnosis had not been suspected before biopsy. Cultures were negative for mycobacteria in all patients. An additional ten patients who had a tibial non-union and latent osteomyelitis were studied. In nine of them, cultures of material obtained by needle biopsy showed no growth. Six of these nine patients had an exacerbation of the osteomyelitis after intramedullary nailing for the non-union. Therefore, the absence of growth of organisms from tissue obtained at needle biopsy does not rule out the possibility that osteomyelitis may be reactivated after intramedullary nailing with reaming.

Bacteria↗
PubMed1989

The Ilizarov technique in the treatment of infected tibial nonunions.

Five patients with infected tibial nonunions and segmental defects were treated with the method of Ilizarov: application of circular small-wire fixator, corticotomy and bone transport to fill the segmental defect. Four of the five patients developed regenerate bone at the corticotomy distraction site. The one failure was related to a previous surgery--reamed locked nailing of the tibia. Three of the four patients with regenerate bone required open reduction and internal fixation at the nonunion site following bone transport. Superficial pin tract infections, broken wires and psychological intolerance of the frame were frequent but minor problems.

Bone Transplantation↗
PubMed1988

Patellar fixation protected with a load-sharing cable: a mechanical and clinical study.

The stability of patellar fracture fixation protected with a load-sharing cable was studied in cadavers. A transverse patellar osteotomy was produced and stabilized with standard patellar fixation with or without a figure-of-eight cable that extends from the proximal pole of the patella to the tibial tubercle. Standard fixation techniques (interfragmentary cancellous screws or modified tension-band wiring) alone failed after significantly fewer cycles of flexion and extension than did the same fixation when supplemented with a load-sharing cable. In the clinical evaluation of the load-sharing cable, 14 consecutive patients with displaced patellar fractures were treated. No immobilization was used and the patients were started on passive and active range of motion and weight-bearing ambulation in the early postoperative period. Thirteen fractures healed uneventfully. The increased stability of patellar fracture fixation protected with a load-sharing cable offers three advantages: (a) adjunctive casting is unnecessary, (b) comminuted fractures can be "pieced" together anatomically with less concern for loss of fixation, and (c) early postoperative passive and active range of motion can be achieved.

Adolescent↗
PubMed1983

Pseudomonas aeruginosa bone and joint infection in drug abusers.

Thirty-nine sites of Pseudomonas aeruginosa bone and joint infection in thirty-five intravenous drug abusers were treated over a four-year period. Early diagnosis was based on a history of drug abuse and demonstration of the site of infection by a technetium bone scan. Most patients responded to long-term therapy with intravenous aminoglycoside and carbenicillin. Extensive early surgical procedures were rarely indicated except in patients with infection of a large synovial joint.

Adolescent↗
PubMed1980

Mersilene strip suture in repair of disruptions of the quadriceps and patellar tendons.

Disruptions of the extensor mechanism of the knee most commonly involve fracture of the patella. Less frequently, patellar and quadriceps tendons are ruptured either spontaneously or by trauma. Surgical reconstruction of these tendon injuries is complicated by the difficulty in completely neutralizing tensional force across the repair. To overcome this problem, methods have been developed to reinforce the repair with overlapping flaps or fascia lata. Others advocate wire sutures or loops to relieve the tension. These techniques prolong and complicate the initial procedure and in some methods require a secondary operation for removal of wire sutures. To simplify these repairs we have developed a method of end-to-end repairs using 5-mm Dacron polyethylene terephthalate fiber strips manufactured under the trade name of Mersilene (Ethicon, Somerville, NJ). The results of our first ten cases are presented.

Adult↗
PubMed1979

Closed Ender nailing of femoral-shaft fractures.

Closed Ender nailing was used in sixty fractures of the femoral shaft. Follow-up examination in fifty-two cases is reported. There were only two failures of the method, both in fractures with supracondylar extension. Simple transverse and short oblique fractures and those with unicortical comminution were shown to be stable after nailing, while long oblique fractures and lesions with bicortical comminution had a tendency to shorten and often required cerclage wiring, cast-bracing, or traction. The average hospital stay was 23.7 days. The operations were simple and quick. There was one case of osteomyelitis, one of clinically apparent thrombophlebitis, and one of fat-embolism syndrome in a patient with multiple fractures and multisystem injuries. There were no cases of breakage of the nail, delayed union, or non-union. In most cases knee motion returned to the preinjury level, although in five knees removal of the nails was necessary. The two failures of nailing which required plate fixation occurred in fractures extending into the supracondylar region. Therefore, these fractures are not suitable for Ender nailing.

Adolescent↗