Assessment of physiological barriers to nutrition following critical illness

BACKGROUND & AIMS

Nutrition may be important for recovery from critical illness. Gastrointestinal dysfunction is a key barrier to nutrition delivery in the Intensive Care Unit (ICU) and metabolic rate is elevated exacerbating nutritional deficits. Whether these factors persist following ICU discharge is unknown. We assessed whether delayed gastric emptying (GE) and impaired glucose absorption persist post-ICU discharge.

METHODS

A prospective observational study was conducted in mechanically ventilated adults at 3 time-points: in ICU (V1); on the post-ICU ward (V2); and 3-months after ICU discharge (V3); and compared to age-matched healthy volunteers. On each visit, all participants received a test-meal containing 100 ml of 1 kcal/ml liquid nutrient, labelled with 0.1 g ¹³C-octanoic acid and 3 g 3-O-Methyl-glucose (3-OMG), and breath and blood samples were collected over 240min to quantify GE (gastric emptying coefficient (GEC)), and glucose absorption (3-OMG concentration; area under the curve (AUC)). Data are mean ± standard error of the mean (SEM) and differences shown with 95% confidence intervals (95%CI).

RESULTS

Twenty-six critically ill patients completed V1 (M:F 20:6; 62.0 ± 2.9 y; BMI 29.8 ± 1.2 kg/m²; APACHE II 19.7 ± 1.9), 15 completed V2 and eight completed V3; and were compared to 10 healthy volunteers (M:F 6:4; 60.5 ± 7.5 y; BMI 26.0 ± 1.0 kg/m²). GE was significantly slower on V1 compared to health (GEC difference: -0.96 (95%CI -1.61, -0.31); and compared to V2 (-0.73 (-1.16, -0.31) and V3 (-1.03 (-1.47, -0.59). GE at V2 and V3 were not different to that in health (V2: -0.23 (-0.61, 0.14); V3: 0.10 (-0.27, 0.46)). GEC: V1: 2.64 ± 0.19; V2: 3.37 ± 0.12; V3: 3.67 ± 0.10; health: 3.60 ± 0.13. Glucose absorption (3-OMG AUC_0-240) was impaired on V1 compared to V2 (-37.9 (-64.2, -11.6)), and faster on V3 than in health (21.8 (0.14, 43.4) but absorption at V2 and V3 did not differ from health. Intestinal glucose absorption: V1: 63.8 ± 10.4; V2: 101.7 ± 7.0; V3: 111.9 ± 9.7; health: 90.7 ± 3.8.

CONCLUSION

This study suggests that delayed GE and impaired intestinal glucose absorption recovers rapidly post-ICU. This requires further confirmation in a larger population. The REINSTATE trial was prospectively registered at www.anzctr.org.au.

TRIAL ID

ACTRN12618000370202.

Abstract PD3-07: A phase II pre-surgical trial of lapatinib for the treatment of women with HER2 positive or EGFR positive ductal carcinoma in situ

Background: Estrogen receptor (ER)-negative tumors and human epidermal growth factor 2-Neu (HER2) positive breast cancers are known to be more clinically aggressive subtypes of breast cancer and account for 30% of all breast cancers. Women with HER2 + breast cancers, whether ER+ or ER -, require cytotoxic chemotherapy with a HER2-targeting agent, and often have adverse outcomes. Thus, preventive agents are needed to reduce the incidence of these subtypes of aggressive breast cancer. Lapatinib, a dual tyrosine kinase inhibitor, inhibits epidermal growth factor receptors (EGFR) and HER2 kinases and has shown to decrease breast cell proliferation in invasive breast cancer and adjacent premalignant lesions. Therefore, we conducted a multi-institutional randomized Phase II clinical trial to study the effects of the signal transduction inhibitor lapatinib in women with HER2-positive or EGFR-positive ductal carcinoma in situ (DCIS).

Methods: Randomized participants received either lapatinib (750mg, 1000mg, or 1500mg) or placebo daily for 2-6 weeks prior to their surgery. After minimal accrual, the trial was later amended to lapatinib 1000mg or placebo. Pre-treatment breast tissue was obtained from initial diagnostic core biopsy and post-treatment breast tissue was obtained from surgical excision specimen. Blood was obtained prior to surgery to assess serum lapatinib level. Participants kept a daily symptom assessment log and had a cardiac assessment at baseline and prior to surgery. Patients were instructed to take drug up to and including the day before surgery. The dual primary endpoint for this study was change in proliferation in pre- versus post-treatment biopsies between the two treatment arms, as measured by Ki67 as well as toxicity assessment. Secondary endpoints included incidence of DCIS at surgery and modulation of tissue biomarker expression in growth factor receptors (EGFR, ErbB2); phosphorylated growth factor receptor (phospho-ErbB2); signal transduction markers (MAPK, phospho-MAPK); hormone receptors (ER, PR); and p27.

Results:Twenty-two women (mean age: 51; range: 32-66) with HER2+ or EGFR+ DCIS were treated with lapatinib (1,000 or 1,500 mg) or placebo for 2–6 weeks prior to surgical excision. Ki67 expression was significantly decreased in the lapatinib treatment arms compared to placebo (p=0.0122). Diarrhea, fatigue, and skin reactions were notable adverse events that occurred predominately in the lapatinib arm compared to placebo. No grade 3 or 4 events related to the study drug were noted during the study. No changes were noted in cardiac function. DCIS was present in all surgical specimens in both arms. Invasive breast cancer was noted in 1 patient on lapatinib 1000mg and 3 patients on placebo. No statistically significant changes were noted in signal transduction biomarkers

Conclusion:These results demonstrate the effectiveness of lapatinib in reducing proliferation in women with EGFR+ or HER2+ DCIS. Even low-grade toxicities can deter use of an agent in the prevention setting. This and the lack of a risk model for HER2+ and triple negative breast cancer make the development of larger scale clinical prevention trials of lapatinib for the prevention a challenge.

Citation Format: Thomas PS, Contreras A, Pruthi S, Krontiras H, Rimawi M, Garber J, Wang T, Hilsenbeck SG, Vornik LA, Gilmer T, Friedman R, Heckman-Stoddard BM, Dunn B, Kuerer H, Brown PH. A phase II pre-surgical trial of lapatinib for the treatment of women with HER2 positive or EGFR positive ductal carcinoma in situ [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr PD3-07.

EU/US/CTAD Task Force: Lessons Learned from Recent and Current Alzheimer's Prevention Trials

At a meeting of the EU/US/Clinical Trials in Alzheimer's Disease (CTAD) Task Force in December 2016, an international group of investigators from industry, academia, and regulatory agencies reviewed lessons learned from ongoing and planned prevention trials, which will help guide future clinical trials of AD treatments, particularly in the pre-clinical space. The Task Force discussed challenges that need to be addressed across all aspects of clinical trials, calling for innovation in recruitment and retention, infrastructure development, and the selection of outcome measures. While cognitive change provides a marker of disease progression across the disease continuum, there remains a need to identify the optimal assessment tools that provide clinically meaningful endpoints. Patient- and informant-reported assessments of cognition and function may be useful but present additional challenges. Imaging and other biomarkers are also essential to maximize the efficiency of and the information learned from clinical trials.

Abstract OT3-3-01: A multicenter phase II study of docosahexaenoic acid (DHA) in triple negative breast cancer (TNBC) survivors

Background: The development of effective chemopreventive strategies to reduce the risk of TNBC, is a critical unmet need. Obesity is associated with a chronic inflammatory condition in the white adipose tissue of the breast, characterized microscopically by crown-like structures of the breast (CLS-B). The presence and extent of these lesions is associated with a series of proinflammatory mediators, including tumor necrosis factor-α (TNF-α), cyclooxygenase-2 (COX-2), interleukin-1β (IL-1β) and aromatase. Importantly these proinflammatory mediators are known to be involved in breast carcinogenesis. In translational studies to date, the strongest correlations have been seen between CLS-B and TNF-α. Therefore, we aim to evaluate whether treatment with a dietary supplement, DHA, an omega-3 fatty acid, with potent effects on TNF-α, can decrease obesity-related breast inflammation in women.

Trial design: This is a randomized phase II placebo-controlled, double-blinded study of DHA in overweight/obese patients (pts), defined as body mass index (BMI) ≥25 with a history of TNBC. Pts will receive DHA or placebo twice daily for 24 weeks and will undergo core biopsies from normal (non-irradiated contralateral) breast tissue before and after the treatment to determine whether DHA can decrease obesity-related breast inflammation.

Eligibility: Inclusion criteria: 1) Age ≥ 18. 2) BMI ≥ 25. 3) Completed treatment for stage I-III TNBC ≥ 6 months prior. 4) No clinical evidence of disease. 5) Adequate accessible breast tissue for pre- and post- treatment biopsy, consisting of one breast unaffected by invasive cancer, which has not been radiated or surgically augmented. 6) Adequate organ and bone marrow function. 7) ECOG status ≤2. Exclusion criteria: 1) DHA supplementation. 2) Aspirin/NSAID use in the month preceding and during the trial. 3) Therapeutic anticoagulation. 4) Regular use of statins, steroids, or immunomodulators.

Specific aims: The primary objective is to determine whether treatment with DHA for 24 weeks at 1,000 mg twice daily as compared to placebo reduces normal breast tissue levels of TNF-α in overweight/obese pts with a history of TNBC. The secondary objective is to evaluate the effect of DHA on the change from baseline in levels of the following tissue biomarkers: COX-2, IL-1β, aromatase, and CLS-B. Exploratory endpoints include assessment of age as a predictor of CLS-B and inflammatory biomarkers and the evaluation of red blood cell fatty acid levels as a surrogate of DHA compliance.

Statistical methods: Percent change in TNF-α mRNA levels in normal breast tissue between DHA and placebo arm will be compared using two-sample t-test. If normality assumptions are violated, a two-sample Wilcoxon rank-sum test will be used. With 30 subjects in each arm, we will have 80% power to detect effect size as small as 0.74 at 0.05 significance level using a two-sided, two-sample, Student t-test.

Accrual: A total of 60 evaluable pts will be enrolled. Assuming a 10% dropout rate and 10% non-evaluable rate, up to 76 participants will be randomized in this study. This trial is currently enrolling pts.

Contact information: For more information on this trial, please visit clinicaltrials.gov (NCT01849250) or contact Ayca Gucalp MD (gucalpa@mskcc.org).

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr OT3-3-01.

Abstract P1-09-07: Topical 4-OHT trial in women with DCIS of the breast: report of plasma and breast tissue concentration of tamoxifen metabolites

Background: Earlier studies have shown that 1–2mg of 4-hydroxytamoxifen (4–OHT) gel applied to the breast skin reduced cell proliferation in estrogen receptor (ER) positive invasive cancers to a similar degree as oral tamoxifen (TAM), with significantly lower plasma levels. We now report results of a Phase IIB pre-surgical window trial of women with DCIS, designed to obtain pilot data in early lesions. Our ultimate goal is to develop transdermal 4-OHT as an alternative to oral TAM for women at high risk for breast cancer and those with DCIS. The study was closed early because the manufacturer discontinued the drug supply, but remains blinded until all biomarker analysis is complete. Here we report the plasma and breast adipose tissue concentration of TAM metabolites from the topical 4-OHT gel group (4 mg) in comparison with the oral TAM group (20mg).

Methods: Women with DCIS were enrolled, and randomized to 4-OHT gel (4mg/day, 2mg per breast, E: Z isomers = 1:1,) or to oral (Z) TAM (20mg/day) for 4–10 weeks before surgery. Blood was collected on the day of surgery, and breast adipose tissue was collected at surgery. There were a total of 22 patients with matched blood and breast adipose tissue. The concentration of TAM metabolites in plasma and breast tissue was determined with liquid chromatography/tandem mass spectrometry. We assumed that the subjects with detectable N-desmethyl TAM (NDT) in plasma belong to the oral TAM group because NDT is not a product of 4-OHT metabolism. Under this assumption, 13 subjects were categorized into oral TAM group, and 9 subjects into the topical 4-OHT group. Wilcoxon rank-sum test was used for statistical analysis.

Results: The results are shown in the table. The concentration is presented as mean ± SD; the lowest quantitation limit (LQL) was 1 ng/mL for plasma, and 3 ng/g for tissue. TAM and its metabolites were found in the plasma of the presumed oral TAM group, with high levels of TAM and NDT. In the presumed 4-OHT gel group, only (Z) 4-OHT was found in the plasma although both (E) and (Z) forms were applied. The mean plasma level of 4-OHT in the gel group was 70% lower than the mean of 4-OHT in the oral TAM group (p = 0.004). In breast tissue, similar amounts of (E) and (Z) forms of 4-OHT were found in the 4-OHT gel group, with the (Z) 4-OHT level being equivalent to that in the oral TAM group (p = 0.48). Endoxifen was only found in the oral TAM group. We saw no evidence of further metabolic transformation of 4-OHT in the breast following topical administration.

Electrically conductive, immobilized bioanodes for microbial fuel cells

The power densities of microbial fuel cells with yeast cells as the anode catalyst were significantly increased by immobilizing the yeast in electrically conductive alginate electrodes. The peak power densities measured as a function of the electrical conductivity of the immobilized electrodes show that although power increases with rising electrical conductivity, it tends to saturate beyond a certain point. Changing the pH of the anode compartment at that point seems to further increase the power density, suggesting that proton transport limitations and not electrical conductivity will limit the power density from electrically conductive immobilized anodes.

Incorporation of Polyaniline Into a Silica Gel Via the Sol-Gel Technique

The sol-gel process has been used to incorporate a conjugated polymer, polyaniline, in silica gel. The emeraldine base form of the polymer is partially solubility in aprotic polar solvents which are compatible with the sol. The effect of sol environment on the emeraldine base form of polyaniline was investigated. The soluble emeraldine base form is maintained at pH ≥ 2.4 enabling good optical quality gels to be synthesized. The type of alkoxysilane and the water ratio used in preparing the sol influence the solubility of the emeraldine base.

The Optical Behavior of Organic and Organometallic Molecules in Sol-Gel Matrices

The low temperatures involved in sol-gel processing have enabled organic and organometallic molecules to be incorporated in gel matrices. These molecules serve as optical probes to characterize gel chemistry and structure. The present paper describes the use of luminescence spectroscopy to detail matrix rigidity effects and protonation/deprotonation reactions during the sol-gel transition and subsequent aging processes. In separate experiments, the addition of a laser dye, rhodamine 6G, has enabled us to demonstrate lasing and optical gain in a silica gel.

MorphÒlogy and Properties of Vanadium Oxide Xerogels and Aerogels

The high redox potential and ion insertion properties of vanadium pentoxide have made this material a viable cathode for secondary lithium batteries. The use of sol-gel methods to synthesize vanadium pentoxide and other transition metal oxides has been well studied as the technique represents a relatively simple approach for preparing thin films and powders. Although it is well known that sol-gel processing may be used to prepare high surface area aerogels, the research on transition metal oxides has been largely limited to xerogels. The present paper compares the properties, structures and morphologies of vanadate xerogels and aerogels.

Advances in Dye-Doped Sol-Gel Lasers

The sol-gel process is a solution synthesis technique which provides a low temperature chemical route for the preparation of rigid transparent matrices. A number of laser dyes have been incorporated in different sol-gel matrices and tunable laser action has been demonstrated with these materials. This paper extends the sol-gel laser field into two significant areas, infrared dyes and pyrromethenes. The work with the tricarbocyanine dyes shows the versatility of sol-gel chemistry as organic modifications produce a favorable environment for the dye molecules. The results with the pyrromethene system show a considerable increase in output energy and offer the promise of longer laser lifetimes.

Preparation and Properties of Porous Bismuth Films

The use of chemical solution routes to form inorganic thin films is a relatively new method which represents an alternative to vapor phase routes. The present study involves the use of a chemical solution route, the decomposition of metal carboxylates, to prepare bismuth thin films of controlled porosity. Such morphologies offer the opportunity to disrupt phonon transport without greatly affecting electrical conductivity and bismuth represents a well known system in which to investigate these effects. Porous bismuth thin films have been prepared using bismuth 2-ethylhexanoate (Bi[OOCCH(C2H5)C4H9]3) as the precursor in a solvent of 2-methyl- 1-propanol. The solution is deposited on glass, Kapton, silicon, alumina or magnesia substrates by spin coating and heated to between 250 – 300°C in hydrogen. Heat treatment temperature and time are important for controlling film microstructure as both pore volume (25 to 50%) and preferred orientation depend upon heat treatment conditions. Bismuth films (62 nm thick) with 32% porosity exhibit conductivities in the range of 150 S/cm with Seebeck coefficients comparable to that of bulk materials.

Proteins Encapsulated in Porous Sol-Gels: Biomolecules as Pore Structure Templates

Porous inorganic SiO2 glasses obtained by the sol-gel route represent a unique matrix for encapsulation of biomolecules wherein the pores act as enclosures for high molecular weight proteins. These hybrid materials are characterized by a pore-biomolecule interface between the pore walls and the protein surface. As a specific model protein, cytochrome c (cyt c) is used to elucidate the nature of physical and chemical interactions between the pores of the matrix and the protein. Evidence from optical absorption, and resonance Raman (RR) spectroscopy methods indicates that the dopant protein alters the structural features of the pore walls. The optical and vibrational measurements strongly suggest that the pores that contain the trapped protein undergo little or no structural change during aging and drying as compared to protein-free pores. Vibrational RR analysis of the trapped cyt c also suggests that the protein resides in a pore where the pore dimensions conform to the shape of the protein. The results indicate that noncovalent interactions between the surface of the protein and the pore walls govern the dynamics of pore formation during gelation and individual biomolecules act as structural templates to design local pore structure.

Microarray karyotyping of maltose-fermenting Saccharomyces yeasts with differing maltotriose utilization profiles reveals copy number variation in genes involved in maltose and maltotriose utilization

AIMS

We performed an analysis of maltotriose utilization by 52 Saccharomyces yeast strains able to ferment maltose efficiently and correlated the observed phenotypes with differences in the copy number of genes possibly involved in maltotriose utilization by yeast cells.

METHODS AND RESULTS

The analysis of maltose and maltotriose utilization by laboratory and industrial strains of the species Saccharomyces cerevisiae and Saccharomyces pastorianus (a natural S. cerevisiae/Saccharomyces bayanus hybrid) was carried out using microscale liquid cultivation, as well as in aerobic batch cultures. All strains utilize maltose efficiently as a carbon source, but three different phenotypes were observed for maltotriose utilization: efficient growth, slow/delayed growth and no growth. Through microarray karyotyping and pulsed-field gel electrophoresis blots, we analysed the copy number and localization of several maltose-related genes in selected S. cerevisiae strains. While most strains lacked the MPH2 and MPH3 transporter genes, almost all strains analysed had the AGT1 gene and increased copy number of MALx1 permeases.

CONCLUSIONS

Our results showed that S. pastorianus yeast strains utilized maltotriose more efficiently than S. cerevisiae strains and highlighted the importance of the AGT1 gene for efficient maltotriose utilization by S. cerevisiae yeasts.

SIGNIFICANCE AND IMPACT OF THE STUDY

Our results revealed new maltotriose utilization phenotypes, contributing to a better understanding of the metabolism of this carbon source for improved fermentation by Saccharomyces yeasts.

Quantitative amino acid analysis

Colorimetric dye-binding assays are often used to determine protein concentration, however, many proteins do not bind dyes in the same way as the proteins normally used as standards, making quantitation by those techniques difficult. This unit describes the information that can be derived from quantitative amino acid analysis (including precise determination of protein concentration), presents some details on sample preparation, and gives examples of the calculations that are needed.

Preparation of protein extracts from yeast

Three protocols are presented for preparing protein extracts; they differ primarily in the way the cells are broken. In the basic protocol, cells are enzymatically converted to spheroplasts, which are then lysed by a combination of osmotic shock and Dounce homogenization. A support protocol for isolating intact nuclei by differential centrifugation is also presented. An alternate protocol describes mechanical breakage of cells by vortexing in the presence of glass beads. In a second alternate protocol, growing cells are frozen immediately in liquid nitrogen and then lysed by grinding in an industrial-strength blender in the presence of liquid nitrogen.

Spatial trends and factors affecting variation of organochlorine contaminants levels in Canadian Arctic beluga (Delphinapterus leucas)

Organochlorine pesticides and PCBs were analysed in blubber from beluga (Delphinapterus leucas), or white whales, collected at 15 sites in the Canadian Arctic between 1993 and 2001. The objective of the study was to define and interpret the spatial trends of major organic contaminants in northern beluga in terms of sources and transport pathways, and the biological factors influencing accumulation. When compared on a lipid weight basis, the concentrations of beta-HCH, cis-CHL and SigmaCHL, cis-nonachlor, heptachlor epoxide and p,p'-DDT were significantly higher in males than females at all five sites in the eastern Arctic where the two sexes were harvested. The differences were attributed to losses from the females during fetal development and lactation as reported in previous studies. Major compounds increased with age in males at most sites, however the lack of a significant increase with age at some sites was in part due to high organochlorine concentrations in young year classes (2-5 years), particularly at eastern sites such as Iqaluit and Pangnirtung. Lower concentrations of SigmaHCH and SigmaDDT compounds in young males in 2001 relative to 1995 at Hendrickson Island could be due to declining levels in the environment, changes in the diet, or differences in organochlorine loads transferred from the female after birth. Age-corrected least square mean concentrations in males showed significantly higher levels of many compounds, such as p,p'-DDE and SigmaCHB, at south Baffin Island sites than those in the west. Two notable exceptions were HCBz and beta-HCH which were higher in the west. Methoxyclor was detected in males at Sanikiluaq (58 ng g-1) and in both sexes at Kimmirut, but at no other sites. Principal component analysis grouped the 16 sites into five major groupings based on the similarity of normalised organochlorine pesticide and PCB levels. Sites from the western Arctic were grouped by higher proportions of HCBz, beta-HCH and gamma-HCH and higher chlorinated PCBs. Endosulfan and alpha-HCH comprised a larger proportion of total organochlorine residues in the northern Hudson Bay sites, while methoxychlor, chlordane compounds and octachlorobiphenyls were enriched at Sanikiluaq in eastern Hudson Bay. The analysis showed that the relative amounts of several key compounds are similar in the beluga stocks over large spatial areas (i.e. eastern versus western sites), however, some stocks have distinct fingerprints which can be used to differentiate them from adjacent stocks. Ratios of major HCH isomers largely corresponded with air and surface water measurements conducted during the 1990s, but low alpha-/beta- and alpha-/gamma-HCH ratios in all three western Arctic collections indicate rapid losses of the alpha-isomer from the food web, proportionately higher beta- and gamma-isomers in the Beaufort Sea, or a combination of the two processes. Chlordane residue patterns generally correspond to those from previous studies, however, interpretation of spatial trends are difficult due to the aging of the probable sources in the south, possible atmospheric input from new sources and complex transport pathways.

Concentrations of mercury in tissues of beluga whales (Delphinapterus leucas) from several communities in the Canadian Arctic from 1981 to 2002

Beluga whales have been hunted for food by Native People in the Canadian Arctic since prehistoric time. Here we report the results of analyses of total mercury in samples of liver, kidney, muscle and muktuk from collections over the period 1981-2002. We compare these results with human consumption guidelines and examine temporal and geographic variation. Liver has been analyzed more frequently than other organs and it has been used as the indicator organ. Mercury accumulates in the liver of the whales over time so that the whale ages are usually linked statistically to their levels of mercury in liver. Virtually all the samples of 566 animals analyzed contained mercury in liver at concentrations higher than the Canadian consumption guideline of 0.5 microg g-1 (wet weight) for fish. (There is no regulatory guideline for concentrations in marine mammals in Canada.) Samples from locations in the Mackenzie Delta in the western Canadian Arctic and from Pangnirtung in the eastern Canadian Arctic were obtained more often than from other location and these offered the best chances to determine whether levels have changed over time. Statistical outlier points were removed and the regressions of (ln) mercury in liver on age were used to calculate the level of mercury in whales of age 13.1 years in order to compare age-adjusted levels at different locations. These age-adjusted levels and also the slopes of regressions suggested that levels have increased in the Mackenzie Delta over the sampling period although not in a simple linear fashion. Other locations had fewer collections, generally spread over fewer years. Some of them indicated differences between sampling times but we could not establish whether these differences were simply temporal variation or whether they were segments of a consistent trend. For example, the levels in whales from Arviat were considerably higher in 1999 than in 1984 but we have only two samples. Similarly, samples from Iqaluit in 1994 exceeded considerably those in 1993 and the interval seems too short to reflect any regional temporal trend and more likely represent an extreme case of year-to-year variation. Previous analyses of data from geographically distinct groups had suggested that whales in the western Canadian Arctic had higher levels of mercury than those from the eastern Canadian Arctic. The present analysis suggests that such regional differences have diminished and are no longer statistically significant. No site has indicated significant decreases in more recent samples. The levels of total mercury in the most analyzed organs fell in the order of liver (highest levels), kidney, muscle and muktuk (lowest level). While muktuk had the lowest level of the organs most frequently analyzed, it is the preferred food item from these whales and it still exceeded the consumption guideline in most instances.