SEARCH · PubMed Health

Results for “SEALS”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 163 records · Page 9Linked to original sources

PubMed1985

Loss of preservative from a tuberculin solution in rubber stoppered vials fastened with different seals.

A tuberculin purified protein derivative (PPD) solution containing 0.3% phenol as a preservative was dispensed in glass vials closed with rubber stoppers fastened in three different ways, namely with Tear-off seals, Flip-off seals and partial seals. After various times of storage at 5 degrees C and 37 degrees C, the phenol content in the tuberculin solution was determined. It was found that the Flip-off seals allowed the phenol to escape at a faster rate than the Tear-off seals and that vials closed with partial seals showed the highest loss of phenol. Although these losses were much more pronounced at 37 degrees C than at 5 degrees C, the phenol content at the latter temperature was, over a period of three years, within the limits of acceptability for tuberculin products capped with Tear-off or Flip-off seals. A loss of phenol also occurred from tuberculin solution stored at -28 degrees C in vials capped with either Tear-off or partial seals. In addition to the Tear-off and Flip-off seals other seals such as the "controlled score' Flip-off seal and the Alcoa Steri-Twist cap were evaluated for their imperviousness to air. Except for the Alcoa Steri-Twist cap none of the seals we have investigated were air tight and hence entirely satisfactory to prevent losses of phenol by evaporation from tuberculin products.(ABSTRACT TRUNCATED AT 250 WORDS)

Drug Packaging↗

PubMed1976

On the adequacy of the draw-sealing of gas-filled glass ampoules.

It is recommended that a very clear distinction be made between draw-sealed and tip-sealed glass ampoules. We would, that is, defend the draw-seal for its proven value and its demonstrated freedom from microscopic channels. Where tip-sealing is still employed, we would suggest its reevaluation. Little more can be said in the absence of an immediate reason for the differences in the behavior of the glass in the course of the two procedures. Others may be able to explain the persistence of the capillary in the tip-seal in physico-chemical terms. As to balloon-seals, the third "variety" in common use, it would seem that their characteristics must derive from the way they are made. Ballooned tip-seals appear to have been shown by Greiff et al. (1975) to suffer the same shortcomings as the simple tip-seal. Where a draw-sealed ampoule is heated at the tip after the completion of the seal, a ballooned end would seem to have to retain the true seal effected in the draw process. It is perhaps sufficient to let the subject rest with a reassurance as to the adequacy of the common draw-seal.

Argon↗

PubMed2003

In vitro evaluation of different techniques of enamel preparation for pit and fissure sealing.

PURPOSE: To compare the penetration and the imperviousness of two pit and fissure sealants according to surface treatments involving different cleaning procedures with or without subsequent acid etching. MATERIALS AND METHODS: Two sealants were used: a resin-based sealant (Concise White Sealant) and a compomer-based material (Dyract Seal) coupled with an enamel-dentin bonding agent (Dyract Seal and Prime&Bond NT). Extracted molars (n = 120) were randomly divided into 12 groups: 4 control and 8 experimental groups that received different surface treatments. Pumice, alumina, or bicarbonate was used to clean the surfaces. Phosphoric acid or non-rinse conditioner was used as acid etching agents. After sealing, the Concise White Sealant groups were directly thermocycled for 1800 cycles, while the Dyract Seal groups were stored in water for one month before thermocycling. After apex sealing and varnish coating, the fillings were stained with silver nitrate and embedded. Three to 6 cross sections of 200 microm each were made per sample to assess both sealant penetration (% of the length of the fissure) and the imperviousness of the seal (scores method). RESULTS: Concise White Sealant achieves a better enamel sealing than Dyract Seal when the teeth are treated with air abrasion or air polishing followed by etching. Acid etching is essential for good sealing, whatever the material and cleaning technique tested. Only the combination of air abrasion and phosphoric acid etching yielded a leak-free joint. CONCLUSION: This study clearly shows that penetration and sealing are two different phenomena. Ideally, an efficient sealant must have a good sealing ability and a high rate of infiltration as well, but these two properties probably do not have the same clinical relevance. The imperviousness of the seal remains the most important requirement.

Acid Etching, Dental↗

PubMed2002

Persistent organochlorine contaminants and enantiomeric signatures of chiral pollutants in ringed seals (Phoca hispida) collected on the east and west side of the Northwater Polynya, Canadian Arctic.

To examine the influence of diet and age on organochlorine contaminant (OC) concentrations in two closely related ringed seal (Phoca hispida) populations enantiomeric fractions (EFs) of chiral contaminants and stable isotopes of nitrogen (delta15N) and carbon (delta13C) were measured along with OCs in ringed seals collected from the east and west side of the Northwater Polynya. Seals from these two locations were feeding at the same trophic level based on delta15N values in muscle but had slightly different sources of carbon based on delta13C measurements in muscle. After removing the influence of age, sex, and blubber thickness, OC concentrations did not vary between ringed seals from the east and west side of the polynya. SigmaPCB, SigmaDDT, and Sigmachlordane were found to increase with age for both male and female seals. The inclusion of older (>20 years) female seals, which may have a reduced reproductive effort, may influence the relationships in females. Stable isotopes failed to describe OC concentrations in ringed seals suggesting that diet was not a major factor in variation of OC concentrations within this ringed seal population. Cis- and trans-chlordane, oxychlordane, and heptachlor epoxide were all nonracemic in the ringed seal blubber but did not vary with age, sex, or collection site. Alpha-HCH appeared racemic (enantiomeric fraction = 0.50 +/- 0.01) in the seals, although this EF is different than those previously observed in their prey species, and was found to vary significantly with age. EF values in the ringed seals varied considerably from other Arctic marine mammals and seabirds, providing addition evidence that the type(s) and characteristic(s) of the enzymes involved in biotransformation of chiral OCs vary between these organisms.

Adipose Tissue↗

PubMed1995

Sealworm (Pseudoterranova decipiens) infection in common seals (Phoca vitulina) and potential intermediate fish hosts from the outer Oslofjord.

Infection with Pseudoterranova decipiens in 45 common seals (Phoca vitulina) from the outer Oslofjord was investigated. Seals were collected before and during the phocine distemper virus epizootic in 1988 when the seal population in the area was reduced from about 350 to 100. In 1989, cod (Gadus morhua) and other fish species were sampled for comparison with earlier investigations on prevalence and abundance of P. decipiens infection in fishes from the outer Oslofjord. Seventy-two per cent of cod were infected with P. decipiens larvae in shallow waters between the seal skerries; the corresponding abundance was 2.2. At other fishing sites at increasing distances from the seal colony, abundance dropped to 0.05-0.20. Otoliths recovered from stomachs and scats indicated that gadids (Micromesistius poutassu, Trisopterus esmarkii and G. morhua) made up more than 80% of the seal diet. Bullrout (Myxocephalus scorpius) was also heavily infected with P. decipiens (prevalence 93% and abundance 8.4), but was not found in the seal diet. However, uninfected cod that enter shallow water from the surrounding deep waters became infected when they feed on bullrout. Recruitment to mature stock of P. decipiens occurs when highly infected cod are eaten by seals. The number of reproducing P. decipiens is very low in common seals. Only 2 seals (i.e. less than 5% of the sample) were simultaneously infected with mature worms of both sexes. The dramatic reduction of the seal stock in the outer Oslofjord by the epizootic did not seem to affect the abundance of P. decipiens in its intermediate hosts.

Animals↗

PubMed1997

Organochlorine contaminants in blubber of four seal species: integrating biomonitoring and specimen banking.

Blubber samples from four Alaska seal species (bearded seal, Erignathus barbatus, harbor seal, Phoca vitulina, northern fur seal, Callorhinus ursinus, ringed seal, P. hispida) were collected for inclusion in the US National Biomonitoring Specimen Bank, as well as for immediate analysis as part of the contaminant monitoring component of the US National Marine Fisheries Service's Marine Mammal Health and Stranding Response Program. The blubber samples were analyzed for organochlorine (OC) contaminants (e.g., PCB congeners, pesticides, DDTs). Results for bearded and ringed seals from the Alaska Arctic revealed low blubber concentrations of OC contaminants. Harbor seals from Prince William Sound. Gulf of Alaska, had somewhat higher blubber concentrations of OC contaminants. In contrast, northern fur seals sampled from the Pribilof Islands had blubber concentrations of certain OC contaminants that were about an order of magnitude higher than those found in the other seal species. Differences in contaminant concentrations among the Alaska seals may be explained by differences in feeding habits and migratory patterns, age or gender did not appear to account for the differences observed. The highest concentrations of OCs were found in harbor seals stranded along the northwestern US mainland, which is consistent with higher concentrations of anthropogenic contaminants being found in urban coastal areas than in more remote Arctic environments. The integration of real-time contaminant monitoring with specimen banking provides important baseline data that can be used to plan and manage banking activities. This includes identifying appropriate specimens that are useful in assessing temporal trends and increasing the utility of the banked samples in assessing chemical contaminant accumulation and relationships to biological effects.

Adipose Tissue↗

PubMed1997

Temporal trends in antibody production in captive grey, harp and hooded seals to a single administration immunocontraceptive vaccine.

The temporal production of antibody to a single-administration immunocontraceptive vaccine, known to be immunocontraceptive in free-ranging female grey seals (Halichoerus grypus), was studied in captive grey seals, harp seals (Phoca groenlandica) and hooded seals (Cystophora cristata). The vaccine is based on liposome delivery of porcine zona pellucida antigens. When measured by antigen capture, the response of hooded and harp seals to the vaccine was similar to the response of grey seals. Determination of antibody production by ELISA with protein A, ELISA with rabbit anti-seal immunoglobulin sera and SDS-PAGE after affinity chromatography confirmed the similarity in response to the vaccine by grey and harp seals, but suggested lower titers in hooded seals. The vaccine produced titers in captive, juvenile grey and harp seals known to be immunocontraceptive in wild, adult grey seals.

Animals↗

PubMed2002

cDNA cloning and characterization of an aryl hydrocarbon receptor from the harbor seal (Phoca vitulina): a biomarker of dioxin susceptibility?

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) and related planar halogenated aromatic hydrocarbons (PHAHs) are found at high concentrations in some marine mammals. Species differences in sensitivity to TCDD and PHAHs are a major limitation in assessing the ecological risk to these animals. Harbor seals accumulate high levels of PHAHs and are thought to be highly sensitive to the toxic effects of these compounds. To investigate the mechanistic basis for PHAH toxicity in harbor seals (Phoca vitulina), we sought to characterize the aryl hydrocarbon receptor (AHR), an intracellular protein that is responsible for PHAH effects. Here we report the cDNA cloning and characterization of a harbor seal AHR. The harbor seal AHR cDNA has an open reading frame of 2529 nucleotides that encodes a protein of 843 amino acids with a predicted molecular mass of 94.6 kDa. The harbor seal AHR protein possesses basic helix-loop-helix (bHLH) and Per-ARNT-Sim (PAS) domains. It is most closely related to the beluga AHR (82%) and human AHR (79%) in overall amino acid identity, indicating a high degree of conservation of AHR structure between terrestrial and some marine mammals. The ligand binding properties of the harbor seal AHR were determined using protein synthesized by in vitro transcription and translation from the cloned cDNA. Velocity sedimentation analysis on sucrose gradients showed that the harbor seal AHR exhibits specific binding of [(3)H]TCDD. The [(3)H]TCDD-binding affinity of the harbor seal AHR was compared with that of the AHR from a dioxin-sensitive mouse strain (C57BL/6) using a hydroxylapatite assay. The equilibrium dissociation constants of seal and mouse AHRs were 0.93+/-0.19 and 1.70+/-0.26 nM, respectively. Thus, the harbor seal AHR bound TCDD with an affinity that was at least as high as that of the mouse AHR, suggesting that this seal species may be sensitive to PHAH effects. The characteristics of the AHR potentially can be used as a biomarker of susceptibility to dioxin-like compounds, contributing to the assessment of the risk of these compounds to marine mammals and other protected animals.

Amino Acid Sequence↗

PubMed2004

Experimental Toxoplasma gondii infection in grey seals (Halichoerus grypus).

Laboratory-reared animals were used to assess the susceptibility of seals (Halichoerus grypus) to Toxoplasma gondii infection. Four seals were each orally inoculated with 100 or 10,000 oocysts of T. gondii (VEG strain), and another 4 seals served as negative controls. Occasionally, mild behavioral changes were observed in all inoculated seals but not in control animals. A modified agglutination test revealed the presence of antibodies to T. gondii in sera collected from inoculated seals and mice inoculated as controls. No evidence of the parasite was found on an extensive histological examination of seal tissues, and immunohistochemical staining of tissue sections from inoculated seals revealed a single tissue cyst in only 1 seal. Control mice inoculated with 10 oocysts from the same inoculum given to seals became serologically and histologically positive for T. gondii. Cats that were fed brain or muscle tissue collected from inoculated seals passed T. gondii oocysts in feces. This study demonstrates that T. gondii oocysts can establish viable infection in seals and supports the hypothesis that toxoplasmosis in marine mammals can be acquired from oocysts in surface water runoff and sewer discharge.

Animals↗

PubMed2006

Continued decline of an Atlantic cod population: how important is gray seal predation?

The continental shelf ecosystem on the Eastern Scotian Shelf (ESS) has experienced drastic changes. Once common top predators are a small fraction of their historical abundance, and much of the current community structure is now dominated by pelagic fishes and invertebrates. Embedded within this food web, Atlantic cod and gray seal populations have recently exhibited nearly opposite trends. Since 1984, cod populations have decreased exponentially at a rate averaging 17% per year, whereas gray seals have continued to increase exponentially at a rate of 12%. We reexamined the impact of gray seals on Atlantic cod dynamics using more than 30 years of data on the population trends of cod and gray seals while incorporating new information on seal diet and seasonal distribution. The closure of the cod fishery over 10 years ago allowed for a better estimation of natural mortality rates. We quantified the impact of seals on ESS cod by (1) estimating trends in seal and cod abundance, (2) estimating the total energy needed for seal growth and maintenance from an energetics model, (3) using estimates of the percentage of cod in the total diet derived from quantitative fatty acid signature analysis (QFASA) and of the size-specific selectivity of cod consumed (derived from otoliths collected from fecal samples), and (4) assuming a gray seal functional response. Uncertainties of the model estimates were calculated using the Hessian approximation of the variance-covariance matrix. Between 1993 and 2000, cod comprised, on average, < 5% of a gray seal's diet. Our model shows that, since the closure of the fishery, gray seals have imposed a significant level of instantaneous mortality (0.21), and along with other unknown sources of natural mortality (0.62), are contributing to the failure of this cod stock to recover.

Animals↗

PubMed2006

Efficacy and quality of vessel sealing: comparison of a reusable with a disposable device and effects of clamp surface geometry and structure.

BACKGROUND: During the past few years, a variety of energy-based techniques for vessel ligation have been introduced. With the use of a porcine model and different devices for bipolar vessel sealing (BiClamp and LigaSure), we studied the impact of different clamp surface structures on the efficacy and quality of vessel sealing. METHODS: Eight Swabian Hall pigs underwent splenectomy, nephrectomy, salpingo-oophorectomy, and small bowel resection with the use of bipolar vessel sealing devices designed for open and laparoscopic surgery. Vessel sealing with clamps with a smooth (nonstructured) surface (BiClamp for open surgery and LigaSure for laparoscopic surgery) was compared to that of clamps with a structured (grooved, wafer-like) surface (BiClamp for laparoscopic surgery and LigaSure for open surgery). Measurements of sealed vessels (2- to 7-mm diameter) included the seal failure rate, instrument sticking, and heat-associated morphological vascular wall alterations. RESULTS: Analysis of seal failures did not reveal significant differences between the different devices for both open [BiClamp, 17.9% (17/95); LigaSure, 15.5% (11/71)] and laparoscopic surgery [BiClamp, 2.8% (1/36); LigaSure, 8.6% (3/35)]. Comparing all data of structured versus smooth clamp surfaces, the seal failure rate was lower using clamps with a structured (11.2%) compared to a smooth surface (15.4%). Instrument sticking and thermal spread were found to be significantly increased after sealing with structured surfaces, regardless of whether devices designed for open (p < 0.05 and p < 0.001, respectively) or laparoscopic surgery (p < 0.001 and p < 0.01, respectively) were used. CONCLUSION: Clamps with a structured surface seem to be superior to those with a smooth surface for successful bipolar vessel sealing, as indicated by an increase of thermal spread. However, the more pronounced instrument sticking represents an undesired side effect and should encourage the search for more inert materials to further improve the sealing procedure.

Animals↗

PubMed2000

Expression and inducibility of members in the cytochrome P4501 (CYP1) family in ringed and grey seals from polluted and less polluted waters.

The expression and inducibility of cytochrome P4501A (CYP1A) were investigated in hepatic microsomes of ringed seals (Phoca hispida) and grey seals (Halichoerus grypus) from polluted (Baltic Sea) and less polluted (Svalbard and Sable Island) areas. Liver CYP1A protein levels and activities were assessed by immunoblot analysis and determining catalytic activities towards ethoxyresorufin (EROD) and pentoxyresorufin (PROD). The amount of CYP1A apoprotein and its catalytic activity were increased up to 5-fold in Baltic ringed and grey seal populations in comparison with ringed seals from Svalbard and grey seals from Sable Island. EROD and PROD activities correlated in all seal groups, indicating catalysis by the same CYP form(s). Enzyme kinetic studies suggested that PROD activity is catalysed by CYP1A enzymes in both ringed and grey seals. In immunoblot analysis, a protein was revealed in liver with an antibody against human CYP1B1, indicating that a CYP1B1 like protein could be present in ringed and grey seals. In conclusion, these data strengthen the concept that CYP1A is markedly induced in seals living in polluted waters and that both EROD and PROD activities are mediated by CYP1A forms in the seal liver. In addition, this study provides the first evidence for the presence of a CYP1B like protein in seal liver.

Journal Article↗

PubMed2006

Differential response of arteries and veins to bipolar vessel sealing: evaluation of a novel reusable device.

BACKGROUND: A variety of energy-based techniques for arterial and venous vessel ligation have recently been introduced. Using a porcine model we studied the efficacy of the novel reusable BiClamp versus the standard disposable LigaSure bipolar vessel sealing device. We also compared whether arteries respond differently than veins upon sealing. MATERIALS AND METHODS: In five Swabian Hall pigs, splenectomy and nephrectomy were performed using two different bipolar vessel sealing devices. Measurements of the sealed arteries and veins (diameter 2-7 mm) included rate of seal failure, burst strength, and heat-associated vascular wall morphologic appearance. An additional three animals underwent splenectomy, salpingo-oophorectomy, and small bowel resection, and vessel seals were studied histologically after a seven-day survival period for vessel wall fusion, inflammation, and fibrous organization. RESULTS: Sealing was highly successful, with only one seal failure overall and thus no difference between the two instruments analyzed. The burst pressures of BiClamp-sealed arteries (842 +/- 117 mm Hg) did not differ from that of arteries sealed with LigaSure (856 +/- 102 mm Hg), but were significantly higher than the burst pressures of veins (155 +/- 26 and 216 +/- 71 mm Hg, respectively) (P < 0.05). Independent of the sealing device used, thermal spread was found increased in veins compared to arteries. Histologic analysis after seven days revealed appropriate healing of the vessel wall, including thrombus fibrosis, fibroblast proliferation, and collagen deposition. With both devices, however, the venous but not the arterial walls still presented with massive inflammatory cell infiltrates. CONCLUSION: Our study indicates that the BiClamp device is as appropriate as the LigaSure instrument to successfully ligate 2-7 mm arteries and veins, demonstrating supraphysiological bursting strengths and adequate lumenal fusion healing. However, veins are more prone to collateral tissue damage and inflammatory wall infiltration.

Animals↗

PubMed2000

Experimental evidence of seawater drinking in juvenile hooded (Cystophora cristata) and harp seals (Phoca groenlandica).

This study was undertaken to measure whether young harp seals (Phoca groenlandica) and hooded seals (Cystophora cristata) drink seawater and, if so, to investigate how the excess salt load is handled. Blood and urine samples were collected from hooded seal pups (n = 3) and harp seal pups (n = 3) after 2 weeks of freshwater exposure, at intervals during 3 weeks of seawater exposure and, finally, after 2 weeks of re-exposure to fresh water. Total water turnover, as measured by injection of tritiated water, was 2200 ml x day(-1) and 3300 ml x day(-1) in hooded seals and harp seals, respectively. The extent of mariposia was taken as the difference between total water turnover and influx of water through food (free and metabolic water) and respiratory water exchange. Seawater drinking amounted to 14% and 27% of total water turnover (rH2O) for the hooded seals and harp seals, respectively. Further evidence of mariposia was obtained from an increase in the excretion rate of the urine osmolytes Na+, Cl- and Mg2+, during the period of seawater exposure. It is concluded that water influx due to seawater drinking can not be excluded as a source of error when estimating food consumption of free-ranging harp seals and hooded seals, by use of labeled water techniques.

Age Factors↗

PubMed1994

Diseases and environmental contaminants in seals from the Baltic and the Swedish west coast.

Investigations have shown that Baltic grey seal (Halichoerus grypus) and ringed seal (Phoca hispida) suffer from a disease complex described as a primary lesion in the adrenals causing secondary reactions in various other organs. Studies on historical Baltic grey seal skull bone material show that the prevalence of affected animals started to increase after World War II. The disease complex explains the dramatic decrease in the Baltic grey and ringed seal population during the 1960s and 1970s and is believed to be caused by environmental pollutants. In 1988, about 60% of the harbor seal population (Phoca vitulina) along the Swedish west coast and in the southwestern part of the Baltic died in the PDV epizootic (Phocine Distemper Virus). Whether the course of the epizootic was altered by environmental pollutants is still an open question. Studies on historical harbor seal skull bone material from both the Baltic and the Swedish west coast show that the incidence of skull bone lesions has also increased in these populations since World War II, indicating the presence of unnatural stress factors. After the epizootic, the harbor seal populations both in the Baltic and along the Swedish west coast have increased in number. Chemical analysis of tissues has been performed on the three seal species collected in various areas of the Baltic and the Swedish west coast. The concentrations of 17 metals and non-metal elements, sDDT and PCBs, DDE and PCB methylsulfones, toxaphene, chlordanes, polybrominated diphenyl ethers, PCDDs and PCDFs have been determined in selected groups of seals in order to determine spatial, species and age variations in concentrations. Furthermore, healthy animals have been compared to diseased animals. Spatial variation was found mostly within the group of organohalogenated compounds, a group of contaminants where a strong covariation between the various compounds was also found. On the basis of the analytical results as well as the pathological findings on Baltic seals, the group of DDE and PCB methyl sulfones is tentatively suggested to be more important in explaining the disease complex than coplanar structures including dioxins.

Adrenal Gland Diseases↗

PubMed2004

Total blubber burden of organochlorine pollutants in phocid seals; methods and suggested standardization.

The purpose of the present paper was to investigate methods for calculating the total blubber burden of organochlorine pollutants (OCs) in phocid seals. Harp seals (Phoca groenlandica) were used as the model species. A sample of fat pre-breeding adult females (N = 9) and a sample of thin moulting adult females (N = 7) were collected. From each animal blubber samples from five different body sites (complete blubber columns and samples from different blubber layers), in addition to a sample from a homogenate derived from the entire blubber mass, were analyzed for selected OCs. Significant differences in the concentrations of major OC contaminants were found between inner and outer blubber layer. Within each seal group, no significant difference in OC concentrations was found between homogenates from whole blubber columns from the five different sites of the animals or when comparing these with the OC concentrations found in the blubber sample deriving from a homogenate of the entire blubber mass. When comparing the two seal groups, the mean OC concentrations were significantly higher in the thin seals. However, blubber burden of OCs measured directly and calculated indirectly were not significantly different, and did not vary between the two groups of seals. Since these seals are of the same age and sex group and from the same population, this is not an unexpected result. The present results suggest that comparison of blubber concentrations of OCs in phocid seals should be avoided, especially when comparing differences between geographical areas or for time-trend analyses. For this type of study, we suggest that the blubber burden of OCs is applied as standard in the future. Furthermore, since blubber depth at a specific sampling site is required when using the estimator for calculation of the percent blubber content in phocid seals (the LMD-index), we suggest that this sampling site (central dorsally) is introduced as a standard when sampling blubber for OC analyses in phocid seals.

Adipose Tissue↗

PubMed2004

Endogenous glycogen prevents Ca2+ overload and hypercontracture in harp seal myocardial cells during simulated ischemia.

The purpose of this study was to determine if elevated myocardial glycogen content could obviate Ca(2+) overload and subsequent myocardial injury in the setting of low oxygen and diminished exogenous substrate supplies. Isolated harp seal cardiomyocytes, recognized as having large glycogen stores, were incubated under conditions simulating ischemia (oxygen and substrate deprivation) for 1 h. Rat cardiomyocytes were used for comparison. Freshly isolated seal cardiomyocytes contained approximately 10 times more glycogen than those from rats (479 +/- 39 vs. 48 +/- 5 nmol glucose/mg dry weight (dry wt), mean +/- S.E., n = 6), and during ischemia lactate production was significantly greater in seal compared to rat cardiomyocytes (660 +/- 99 vs. 97 +/- 14 nmol/mg dry wt), while glycogen content decreased both in seal (from 479 +/- 39 to 315 +/- 58 nmol glucose/mg dry wt) and rat cardiomyocytes (from 48 +/- 5 to 18 +/- 5 nmol glucose/mg dry wt). Cellular ATP was well maintained in ischemic seal cardiomyocytes, whereas it showed a 65% decline (from 31 +/- 3 to 11 +/- 1 nmol ATP/mg dry wt) in rat cardiomyocytes. Similarly, total seal cardiomyocyte Ca(2+) content was not affected by ischemia, while Ca(2+) increased from 8.5 +/- 2.0 to 13.3 +/- 2.0 nmol/mg dry wt in ischemic rat myocytes. Rat cardiomyocytes also showed a notable decline in the percentage of rod-shaped cells in response to ischemia (from 66 +/- 4% to 30 +/- 3%), and cell morphology was unaffected in seal incubations. Addition of iodoacetate (IAA, an inhibitor of glycolysis) to seal cardiomyocytes, on top of substrate and oxygen deprivation, reduced the cellular content of ATP by 52.9 +/- 4.4% (from 25 +/- 4 to 11 +/- 2 nmol ATP/mg dry wt) and the percentage of rod-shaped myocytes from 51 +/- 3% to 28 +/- 4%, while total Ca(2+) content was unchanged by these conditions. Seal cardiomyocytes thus tolerate low oxygen conditions better than rat cardiomyocytes. This finding is most likely due to a higher glycolysis rate in seals, fueled by larger myocardial glycogen stores.

Adenosine Triphosphate↗

PubMed2002

Bioaccumulation of radiocaesium in Arctic seals.

Seals are high trophic level feeders that bioaccumulate many contaminants to a greater degree than most lower trophic level organisms. Their trophic status in the marine food web and wide-spread distribution make seals useful sentinels of arctic environmental change. The purpose of this investigation is to document the levels and bioaccumulation potential of radiocaesium in high latitude seal species for which data have not previously been available. The study was carried out on harp, ringed, and bearded seals caught north of the island archipelago of Svalbard (82 degrees N) in 1999. The results are then compared with previous studies in order to elucidate factors responsible for bioaccumulation in Arctic seals. Concentrations of 137Cs were determined in muscle, liver and kidney samples from a total of 10 juvenile and one adult seal. The mean concentration in muscle samples for all animals was 0.23 +/- 0.045 Bq/kg f.w. 137Cs concentrations in both liver and kidney samples were near detection limits (approximately 0.2 Bq/kg f.w.). The results are consistent with previous studies indicating low levels of radiocaesium in Arctic seals in response to a long term trend of decreasing levels of 137Cs in the Barents Sea region. Bioconcentration factors (BCFs) estimated for seals from NE Svalbard are low, ranging from 34 to 130. Comparing these values with reported BCFs for Greenland seals from other sectors of the European Arctic, we suggest that the combination of physiological and ecological factors on radiocaesium bioaccumulation is comparable among different Arctic seal populations. The application of this work to Arctic monitoring and assessment programs is discussed.

Animals↗