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Biomedical subjects

R K Peterson

Publications and source records attributed to R K Peterson.

9 recordsLinked to original sources
PubMed2001

Allograft versus autograft patellar tendon anterior cruciate ligament reconstruction: A 5-year follow-up.

PURPOSE: To compare the long-term results of allograft versus autograft central one-third bone-patellar tendon-bone reconstruction of the anterior cruciate ligament (ACL), 2 groups of 30 patients were evaluated subjectively and objectively at an average follow-up of 63 months (range, 55 to 78 months). TYPE OF STUDY: A prospective nonrandomized study. METHODS: All surgeries were performed endoscopically by a single surgeon using metal interference screw fixation between May 1991 and November 1992. Early aggressive rehabilitation was employed and follow-up visits at 3, 6, 12, 24, and 60 months noted swelling, pain, range of motion, and patellofemoral crepitus, and Lachman test, pivot shift test, and side-to-side arthrometer differences. RESULTS: Results were analyzed using 2-sample t test and chi-square analysis. Average age at surgery for autografts was 25 years (range, 14 to 49) and for allografts was 28 years (range, 14 to 53). The presence of meniscal tears were similar (allografts, 23 tears; autografts, 19 tears). At follow-up, no statistically significant difference was found for the presence of pain, giving way, effusion, Lachman and pivot shift results, or arthrometer measurements. Two patients, 1 allograft and 1 autograft had complete rupture of their grafts. There was no late stretching out of either graft and patients stable at 2 years were stable at 5 years, with the exception of the 1 ruptured graft in each group. CONCLUSIONS: A trend toward a greater incidence of glide on pivot testing was seen in the allografts (4 allografts v 2 autografts) but was present at 2 years and did not change at 5 years. A trend toward greater loss of extension in autografts (2.47 degrees ) than allografts (1.07 degrees ) was seen at 5-year follow-up, not seen at 2 years.

Adolescent↗
PubMed1999

U.S. market basket study to determine residues of the insecticide chlorpyrifos.

A market basket study was conducted to measure residues of the insecticide chlorpyrifos in samples of apples, applesauce, apple juice, fresh orange juice, tomatoes, peanut butter, whole milk, ground beef, and pork sausage collected during a 12-month period from 200 grocery stores across the United States. Approximately 90% of the samples contained no detectable levels of chlorpyrifos, and all residues detected were below tolerances, the legal limits for the United States. No values greater than the limit of quantitation (LOQ) were found in applesauce (LOQ = 0.008 ppm), apple juice (LOQ = 0.003 ppm), whole milk (LOQ = 0.006 ppm), ground beef (LOQ = 0.005 ppm), or pork sausage (LOQ = 0.007 ppm) samples. Only one fresh orange juice sample contained residues greater than the LOQ at 0.015 ppm. Only about 20% of the apples (maximum = 0.052 ppm), 20% of the tomato samples (maximum = 0.058 ppm), and 50% of the peanut butter samples (maximum = 0.021 ppm) contained quantifiable residues.

Animals↗
PubMed1999

Osteochondritis dissecans of the elbow.

Osteochondritis dissecans of the elbow remains one of the leading causes of permanent elbow disability in adolescents and young adults engaged in throwing sports or gymnastics. The insidious onset of lateral elbow pain and restriction of full extension should alert the physician and prompt further investigation. Early recognition and appropriate treatment may allow for the prevention of long-term sequelae. Conservative care following early detection provides the best opportunity for a complete recovery. Surgical management at this point consists primarily of excision or removal of the osteochondral fragment with drilling or burring of the base of the lesion. Prognosis is fair with approximately half of all patients experiencing chronic pain or limitation of motion in the elbow. Research efforts are currently focusing on the treatment of established articular surface defects. Newer procedures such as the transplantation of osteochondral, perichondral, and periosteal tissues, chondrocyte transplantation, and the biochemical manipulation of the chondrocyte environment may provide us with exciting new approaches to an old problem. Osteochondritis dissecans of the elbow continues to present a difficult challenge to the treating physician. The current literature provides very little guidance for the clinician but active and innovative investigations into the treatment of articular cartilage defects may soon provide the answers.

Adolescent↗
PubMed1998

Human exposure and risk from indoor use of chlorpyrifos.

The toxicity, exposure, and risk from chlorpyrifos are briefly discussed in juxtaposition with two recent articles in Environmental Health Perspectives concerning potential exposures to children. In studies conducted according to EPA guidelines, chlorpyrifos has been shown not to be mutagenic, carcinogenic, or teratogenic, nor does it adversely affect reproduction. Chlorpyrifos toxicity does not occur in the absence of significant cholinesterase inhibition. If exposures are less than those that cause significant cholinesterase depression, then no signs or symptoms related to chlorpyrifos exposure occur. The weight of empirical evidence indicates that the risk of adults or children experiencing an adverse health effect from exposure to chlorpyrifos through both nondietary and dietary sources is negligible. Both the research supporting the registration of these products and their long history of widespread use suggest that unless these products are seriously misused, their margins of safety are wide enough to protect everyone with the potential to be exposed. A weight-of-evidence review of the entire scientific knowledge base relating to chlorpyrifos products supports these conclusions.

Adult↗
PubMed1996

TNT and 4-amino-2,6-dinitrotoluene influence on germination and early seedling development of tall fescue.

Cost-effective and environmentally acceptable methods are needed to remediate munitions-contaminated soil. Some perennial grass species are tolerant of soil contaminants and may promote remediation because of their high water use and extensive fibrous root systems. The effects of 2,4,6-trinitrotoluene (TNT) and its reduction product, 4-amino-2,6-dinitrotoluene (4ADNT), on germination and early seedling development of tall fescue (Festuca arundinacea Schreb.) were determined. Tall fescue seeds were germinated in nutrient-free agar containing 0-60 mg TNT litre(-1) or 0-15 mg 4ADNT litre(-1). Germination decreased linearly as TNT concentration increased but was not significantly affected by 4ADNT at these concentrations. Concentrations less than 30 mg TNT litre(-1) or 7.5 mg 4ADNT litre(-1) had little effect on seedling growth and development. Higher TNT or 4ADNT concentrations substantially delayed seedling development, caused abnormal radicle tissue development, and reduced secondary root and shoot growth. Seedling respiration rates decreased linearly with increasing TNT concentration. Experiments indicate that tall fescue may be grown in soils that maintain soil solution concentrations of 30 mg TNT litre(-1) or less.

Journal Article↗
PubMed1996

Compressive neuropathies and tendinopathies in the athletic elbow and wrist.

Overuse syndromes of the upper extremity in the athletic population are a common and often difficult problem for physician and patient alike. Optimal function of the upper extremity is tied intimately to success in many sporting activities. Correct diagnosis and proper care require a thorough knowledge of the pertinent anatomy, pathophysiology, and pathomechanics involved in each disorder. Conservative care with rest, activity modification, and medication is adequate for most athletic injuries. Surgical intervention may be indicated for continuing pain, decreased performance, or to prevent chronic changes. Surgery must be followed by thoughtfully prepared training and rehabilitation programs to optimize the chances of a successful outcome.

Athletic Injuries↗
PubMed1990

Systemic heparinization does not prevent clot formation in coil embolization.

Therapeutic transcatheter closure with Gianturco-type steel coils has been applied to a variety of vascular communications in children with congenital heart disease. Vessel closure depends upon successful thrombus formation around the coil. Since systemic anticoagulation with heparin is commonly used during catheterization and cardiac surgery, we studied the effect of systemic heparinization on the efficiency of vessel occlusion by coil embolization in lambs. Catheters inserted in femoral arteries were used to arteriographically locate and size 36 systemic arteries in 9 lambs weighing 4.2 to 7.4 kg. Twenty-four vessels were embolized prior to heparinization with 400 u/kg heparin, IV. Effective anticoagulation was demonstrated by post-heparin activated clotting time (ACT) values greater than 300 sec. Seven vessels (29%) were not successfully coil-embolized because of inadequate coil position or distant embolization of the coil; 17 (71%) of these vessels were shown to be successfully occluded by arteriography 6 to 77 min later. After a period of systemic heparinization ranging from 71 to 159 min, 9/17 arteries remained occluded, 7/17 could not be examined arteriographically due to early demise of the animal, and only 1/17 showed recanalization. A second group of 12 vessels were embolized after heparinization. Eight (75%) were successfully occluded, and 4 (25%) were not successfully coil-embolized because of inadequate coil position or coil embolization to distant arteries. We conclude that systemic heparinization had no measurable effect on occlusion rates in coil-embolized systemic arteries in the lamb. These data support the use of systemic heparinization, when indicated, during or following therapeutic coil embolization in children.

Animals↗