Soil ingestion rate determination in a rural population of Alberta, Canada practicing a wilderness lifestyle.

The inadvertent ingestion of contaminated soil can be a major pathway for chemical exposure to humans. Few studies to date have quantified soil ingestion rates to develop exposure estimates for human health risk assessments (HHRA), and almost all of those were for children in suburban/urban environments. Here we employed a quantitative mass balance tracer approach on a rural population practicing outdoor activities to estimate inadvertent soil ingestion. This study followed 9 subjects over a 13 day period in Cold Lake, Alberta, near the largest in situ thermal heavy oil (bitumen) extraction operation in the world. The mean soil ingestion rate in this study using Al Ce, La, and Si tracers was 32 mg d(-1), with a 90th percentile of 152 mg d(-1) and median soil ingestion rate of 18 mg d(-1). These soil ingestion values are greater than the standard recommended soil ingestion rates for HHRA from Health Canada, and are similar to soil ingestion estimates found in the only other study on a rural population.

Localized enrichment of polycyclic aromatic hydrocarbons in soil, spruce needles, and lake sediments linked to in-situ bitumen extraction near Cold Lake, Alberta.

The extraction of bitumen from the Alberta oil sands using in-situ technologies is expanding at a rapid rate; however, investigations into the environmental impacts of oil sands development have focused on surface mining in the Athabasca region. We measured polycyclic aromatic hydrocarbons (PAH) in soils, spruce needles, and lake sediment cores in the Cold Lake oil sands region to provide a historical and spatial perspective on PAH contamination related to in-situ extraction activities. A pronounced increase in PAH concentrations was recorded in one of two study lakes (Hilda Lake) corresponding to the onset of commercial bitumen production in ~1985. Distance from extraction rigs was not an important predictor of PAH concentrations in soils, although two samples located near installations were elevated in alkyl PAHs. Evidence of localized PAH contamination in Hilda Lake and two soil samples suggests that continued environmental monitoring is justified to assess PAH contamination as development intensifies.

A pilot study to assess the feasibility of using naturally-occurring radionuclides as mass balance tracers to estimate soil ingestion.

The relatively few soil ingestion studies that have been conducted to date to support soil ingestion rate values used for contaminated site human health risk assessments (HHRAs) typically have measured mass balance elemental tracers (e.g., Al, Si, Ba, Ce, Mn, Ti, V, Zr), found in soil to estimate soil ingestion. This pilot study, involving a canine subject fed a known amount of tracer on a daily basis, assessed the use of alternative mass balance tracers, specifically naturally occurring radionuclides of the (238)U and (232)Th decay series, to estimate soil ingestion. A novel method of estimating soil ingestion via difference in isotopic ratios between the two decay series in food and soil was also assessed. The results of the study showed that the mean (214)Pb and (212)Pb activities measured in fecal samples were greater than what was contained in the soil inoculant, suggesting that the tracers were not being significantly absorbed in the GI tract. The mean daily soil ingestion rates, calculated after subtracting the contribution of tracers in the soil inoculant, were 3.9 g d(-1) (standard deviation 3.6 g d(-1)) for the isotope tracers, and 1.9 g(-1) (standard deviation 2.1 g d(-1)) for the 3 most reliable elemental tracers. The differences were not statistically significant and further evaluation of isotopic tracers for soil ingestion studies is warranted. Similarly, soil ingestion estimates calculated using the Isotope Ratio Method were not significantly different than when calculated using (212)Pb; however, the Isotope Ratio Method was observed to positively bias the soil ingestion estimates by approximately 50%.

Selected melanocortin 1 receptor single-nucleotide polymorphisms differentially alter multiple signaling pathways.

The melanocortin 1 receptor (MC1R) is a highly polymorphic G protein-coupled receptor, which is known to modulate pigmentation and inflammation. In the current study, we investigated the pharmacological effects of select single-nucleotide polymorphisms (SNPs) (V60L, R163Q, and F196L). After transient expression of MC1Rs in human embryonic kidney 293 cells, basal and ligand-induced cAMP signaling and mitogen-activated protein kinase (MAPK) activation were assessed by using luciferase reporter gene assays and Western blot analysis, respectively. All receptor variants showed decreased basal cAMP activity. With the V60L and F196L variants, the decrease in constitutive activity was attributable, at least in part, to a reduction in surface expression. The F196L variant also displayed a significant reduction in potency for both the peptide agonist α-melanocyte-stimulating hormone (α-MSH) and the small-molecule agonist 1-[1-(3-methyl-L-histidyl-O-methyl-D-tyrosyl)-4-phenyl-4-piperidinyl]-1-butanone (BMS-470539). In MAPK signaling assays, the F196L variant showed decreased phospho-extracellular signal-regulated kinase levels after stimulation with either α-MSH or BMS-470539. In contrast, the R163Q variant displayed a selective loss of α-MSH-induced MAPK activation; whereas responsiveness to the small-molecule agonist BMS-470539 was preserved. Further assessment of MC1R variants in A549 cells, an in vitro model of inflammation, revealed an enhanced inflammatory response resulting from expression of the F196L variant (versus the wild-type MC1R). This alteration in function was restored by treatment with BMS-470539. Overall, these studies illustrate novel signaling profiles linked to distinct MC1R SNPs. Furthermore, our investigations highlight the potential for small-molecule drugs to rescue the function of MC1R variants that show reduced basal and/or α-MSH stimulated activity.

A survey of the traditional food consumption that may contribute to enhanced soil ingestion in a Canadian First Nation community.

Soil ingestion rates in the order of 400 mg d(-1) have been proposed and considered plausible for use in human health risk assessments (HHRA) of Aboriginal populations and justified by qualitative assessments of the traditional subsistence activities that could enhance soil ingestion. The purpose of this study was to assess and document the subsistence activities and food consumption practiced by a First Nation Community living in a wilderness community in Canada to allow for a comparison with the previous qualitative assessments of Aboriginal populations and a quantitative mass balance tracer element study of the community conducted concurrently. An ethno-cultural survey was conducted of the Xeni Gwet'in First Nations community living in the Nemiah Valley, approximately 230 km west of Williams Lake, British Columbia. The community diet was observed to consist mainly of fish and big game, and was supplemented by berries and roots. Outdoor cultural gatherings, hunting and food gathering trips and sporting events, with their attendant potential for enhanced soil exposure, were observed to be an important facet of community life. The survey concluded that a significant portion of the Xeni Gwet'in practise a lifestyle similar to the subsistence lifestyles of other indigenous communities, where soil exposure scenarios in the order of hundreds of mg d(-1) have been proposed.

A soil ingestion pilot study of a population following a traditional lifestyle typical of rural or wilderness areas.

The relatively few soil ingestion studies underpinning the recommended soil ingestion rates for contaminated site human health risk assessments (HHRAs) that have been conducted to date assessed soil ingestion in children living in urban or suburban areas of the United States, and to a lesser extent, Europe. However, the lifestyle of populations living in North American urban and suburban environments is expected to involve limited direct contact with soil. Conversely, many populations, such as indigenous and Aboriginal peoples residing in rural and wilderness areas of North America and worldwide, participate in activities that increase the frequency of direct contact with soil. Qualitative exposure of Aboriginal populations inhabiting wilderness areas suggest that high levels of soil ingestion may occur that are many times greater than those recommended by regulatory agencies for use in HHRAs. Accordingly, a study of subjects selected from a wilderness community in Canada was conducted using mass balance tracer methods to estimate soil ingestion and the results compared with previous soil ingestion studies and regulatory guidelines for the soil ingestion rates used in HHRA of contaminated sites. A pilot study of 7 subjects living in the Nemiah Valley of British Columbia was conducted over a 3-week period. The mean soil ingestion rate estimated in this study using the 4 elemental tracers with the lowest food-to-soil ratios (i.e., Al, Ce, La, Si), was observed to be approximately 75 mg d(-1) (standard deviation 120 mg d(-1)), the median soil ingestion rate was 50 mg d(-1), and the 90th percentile was 211 mg d(-1). These soil ingestion rate estimates are higher than the soil ingestion estimates currently recommended for HHRAs of adults, and higher than those obtained in most previous studies of adults. However, the estimates are lower than the earlier qualitative assessments of subsistence lifestyles.

Palmar and digital flexor tendon pulleys.

Retinacular structures, called pulleys, maintain the flexor tendons of the hand in constant relationship to the joint axes and promote economy and efficiency in finger flexion. This system is composed of the transverse carpal ligament, the palmar aponeurosis pulley, and the digital flexor pulley system. Of these three components, the digital pulleys are the most critical to finger flexion. In their normal state, these pulley components are ideal in all aspects including configuration and location, which accomodates a 260 degrees arc of motion without impingement and with minimum friction while at the same time using muscle tendon excursion that is well within the natural range of the muscle. An absent pulley results in an increased moment arm and requires increased tendon excursion to produce the same arc of motion. Because muscle excursion is not a limitless factor and is directly proportional to muscle fiber length, the effectiveness of tendon excursion is dependent on maintenance of the critical relationship between pulleys and the adjacent joints. Preservation and reconstruction of this system is based on knowledge of the anatomy and an understanding of the relative functional significance of each component of the system.

Anatomy of the upper extremity muscle compartments.

Multiple and anatomically distinct compartments are present in the upper extremity. A compartment is defined as an enclosed space formed by fascia or by a combination of fascia and bone that contains one or more muscles. Knowledge of these anatomic compartments and their contents will facilitate early diagnosis and treatment.

Prevalence of hereditary hemochromatosis in a Massachusetts corporation: is Celtic origin a risk factor?

The prevalence of homozygous hereditary hemochromatosis (HHC) is estimated at 1:250 in Caucasian adults. Little is known about ethnic subpopulations that might be at increased risk for this disease. HLA data have suggested a Celtic origin for HHC. Screening for HHC was offered to all employees of the Massachusetts Polaroid Corporation. Participants with a transferrin saturation of >55% or >45% and an elevated serum ferritin concentration on two screenings were referred for liver biopsy. The diagnosis of HHC was based on histological criteria, quantitative hepatic iron determination, hepatic iron index, and the phlebotomy requirement for iron depletion. Participants completed a questionnaire regarding their ethnic background. Two thousand two hundred ninety-four employees were screened, and 5 cases of HHC were detected. All 5 cases involved Caucasian men, yielding a prevalence of 1:395 for the Caucasian population. Four of the 5 cases were of 100% British-Irish ancestry based on the country of origin of their grandparents. Additional analysis revealed that the majority of grandparents of all 4 individuals came from Ireland or Wales. The exact two-tailed trend test showed a significant association of HHC with Celtic background (P = .012). The estimated cost of screening per patient identified was $18,041. Polaroid Corporation has a high representation of employees of British-Irish ancestry. Our data suggest that they are at high risk for developing HHC. A significant association of HHC with Celtic ancestry was found in this subpopulation, supporting the concept of a Celtic origin for this disease.

Outcome following epineurotomy in carpal tunnel syndrome: a prospective, randomized clinical trial.

To assess the efficacy of an adjunctive epineurotomy in carpal tunnel syndrome, 36 wrists in 33 patients were prospectively randomized into epineurotomy and non-epineurotomy treatment groups. The operating surgeons and evaluating therapist were double-blinded. Patients were evaluated preoperatively and at either 6 or 12 months postoperatively, with 15 patients examined at both postoperative time points. Evaluation consisted of five sensory and four motor tests: static and moving two-point discrimination, Semmes-Weinstein monofilament testing, vibratory (30 and 256 cps) sensibility, and dynamometer testing of grip strength and lateral, three-jaw, and tip pinch strengths. Sensory testing showed overall improvement within both groups postoperatively, but there was no difference between the two groups at either 6 or 12 months postoperatively. Motor testing revealed no improvement in the grip strength or lateral, three-jaw, or tip pinch of either group at 12 months when compared to preoperative levels. Twenty-four of 26 epineurotomy patients and all 10 control patients were satisfied with their clinical outcome 30 months after surgery. The addition of an adjunctive epineurotomy, although safe, offered no clinical benefit in the surgical treatment of carpal tunnel syndrome in this series.

Detectionless processing with semantic activation? A footnote to Greenwald, Klinger, and Liu (1989)

Recently published research has suggested that, in a pattern masking task, semantic activation caused by the target may continue to exist even though subjects cannot detect the target. The experiments are reassessed as an exceptional case of the more general rule that subjects are able to use residual semantic activation to actually detect targets. Furthermore, residual graphic information is far less effective at supporting near-chance target detections.

Anatomy and function of the palmar aponeurosis pulley.

The transverse fibers of the palmar aponeurosis are attached by vertical septa to the underlying transverse metacarpal ligament and thus form a pulley over the flexor tendons. It is a constant and substantial retinacular structure that overlays the synovial sheath. Because of its proven function, position and breaking strength, I believe it should be considered part of the flexor tendon pulley system.

A mechanical study of six digital pulley reconstruction techniques: Part I. Mechanical effectiveness.

A laboratory study on fresh-frozen human cadaver limbs compared six types of flexor tendon pulley reconstruction in the fingers. The reconstructions used were those described by (1) Bunnell, (2) Karev, (3) Weilby, and (4) Lister, and two types developed by us that have not been previously described. The pulleys were studied in specific configurations to determine their effectiveness in transforming tendon excursion into finger flexion. In each finger, comparison was made between the amount of tendon excursion required for full flexion with an intact pulley system versus the various types of reconstructed pulleys. The ratio of these two values was defined as the mechanical effectiveness of the pulley reconstruction. The Karve reconstruction was most effective at 108.2%, which was significantly different from the other five reconstructions (p less than 0.01). The remaining reconstructions ranged in effectiveness from 80.0% to 88.5%.

A mechanical study of six digital pulley reconstruction techniques: Part II. Strength of individual reconstructions.

A laboratory study was done on fresh-frozen human cadaver limbs, using six types of pulley reconstructions about the flexor tendons of the fingers. The reconstructions used were those described by (1) Bunnell, (2) Karev, (3) Weilby, and (4) Lister, and two types developed by us that have not been previously described. The pulleys were tested at constant strain rate to failure with the peak force recorded as the breaking strength. A total of 385 reconstructed pulleys were tested and the results were analyzed statistically. A new "loop and one half" pulley reconstruction was significantly stronger than the other five reconstructions (p less than 0.01) with an average load to failure of 22.5 kilograms-force. The other pulley reconstructions varied in average breaking strength from 2.8 kilograms-force to 18.4 kilograms-force.

Congenital anomalies of the upper extremity.

This article has reviewed some of the current methods of management of congenital problems in the upper extremity. Not all problems have been included in this review but some of the landmark advances in this field have been considered. The management of congenital anomalies may change significantly in the future.

Replantation.

Replantation is firmly established as a viable treatment option in many accidental amputations involving the upper extremity. The clinical foundation was laid more than 100 years ago and it is a technique which is now available world wide. The success rate of replantation exceeds 80 per cent. More often than not, appropriately selected patients obtain a functional result which is better than currently available prosthetic devices. The experience gained from small vessel surgery in replantations has aided in the development of reconstructive procedures, including free composite tissue transfers such as toe-to-hand transfers and free flaps.

Nerve suture and grafting.

Nerve anatomy, terminology, and techniques for nerve restoration are reviewed in sufficient detail to allow the reader to quickly update his or her knowledge in this area. Ideas for future directions of study are presented.