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At least 973 records · Page 54Linked to original sources
PubMed1980

Masked hearing thresholds of harbour seals (Phoca vitulina) in air.

Two wild seals, maintained in captivity in good health, were trained to swim on verbal command to a spot 27 cm above the water, and subsequently to make a L or R turn to a pure tone vs no tone. White noise was present at 80, 70, or 60 db SPL. Masked thresholds were determined by a staircase method in 2-db steps at 2, 4, 8.6, and 15 kc/s (at 15 kc/s only noise at 60 db SPL was presented). Critical bandwidths in db were calculated, all of the order of 25 db (range of to 28 db). These values are close to those reported by Terhune and Ronald (J. Acoust.Soc.Am., 1975, 58, 515-516) for seals' aerial hearing but are unexplainably lower (i.e., worse) than for seals underwater. It was calculated that in their often noisy and visually restricted natural environment, a mother would not be able to hear her pup if separated by more than 8 m. This situation was generally corroborated by field observation on the breeding grounds.

Animals↗
PubMedDate not supplied

Determination of chlorobiphenyls in cleaned-up seal blubber and marine sediment extracts: interlaboratory study.

An interlaboratory study on the determination of individual chlorobiphenyl congeners (CBs) in cleaned-up seal blubber and marine sediment extracts was organized by the International Council for Exploration of the Sea, the Intergovernmental Oceanographic Commission, and the Oslo and Paris Commissions, as the second part of a step-wise-designed interlaboratory study on the determination of CBs in marine media. Fifty-eight laboratories from 16 countries participated in this exercise, which involved the determination of 10 CBs in a standard solution, a cleaned-up seal blubber extract, and a cleaned-up marine sediment extract. Suggestions were given for instrument optimization. Standard errors of 1.16-1.17 for the standard solution, 1.20-1.33 for the seal blubber extract, and 1.31-1.56 for the sediment extract were obtained for CBs 52, 101, 118, 138, 153, and 180 by all laboratories with the exception of the laboratories giving consistently outlying results. The results for CBs 28, 31, 105, and 156 showed larger standard deviations. The 2 major difficulties for participants in this exercise were correct preparation of a calibration solution and chromatographic separation. The results of the sediment analysis showed a complete lack of agreement. It is recommended that, prior to the organization of the third part of this study, participants should install gas chromatographic columns with minimum lengths of 50 m and maximum internal diameters of 0.25 mm and should prepare calibration solutions from solids of known purity.

Adipose Tissue↗
PubMed1994

Transfer of fat-soluble vitamins and PCBs from mother to pups in grey seals (Halichoerus grypus).

Lactation in seals is characterized by a rapid and enormous lipid transfer from mother to pups within a milk rich in lipids. Since grey seals do not feed during lactation, all milk constituents are solely derived from body stores. Monitoring levels of fat-soluble vitamins as well as PCBs in blubber and milk may give an insight into the mechanisms involved in their mobilization from blubber, transfer into milk and deposition in the blubber of pups. During lactation, total lipids in milk increased from 261 to 601 g/l. While the level of PCBs in milk per g lipid remained constant throughout lactation, vitamin E, as well as vitamin A and cholesterol, showed a marked decrease during lactation when expressed as quantity per unit lipid. An incomplete transfer of all components from maternal blubber to milk was observed, except for vitamin E. The milk of pregnant females had vitamin E levels per unit which were three times higher than that in blubber, indicating a mobilization of vitamin E from the liver. During the later stages of lactation, there were no differences between the levels of vitamins A and E per unit lipid in the milk and the blubber of suckling pups. The close correlation of PCBs with total milk lipids and the drastic decrease in all other monitored fat-soluble components in seal milk with the progress of lactation point to different mechanisms of mobilization and transport for triglycerides and PCBs compared to fat-soluble vitamins and cholesterol.

Adipose Tissue↗
PubMedDate not supplied

[Neutralizing morbillivirus antibodies in the population of the Baikal seal Phoca sibirica].

The antibodies neutralizing Baikal seal morbillivirus (BSMV) were studied in sera from 148 normal Baikal seals (Phoca sibirica). The virus-neutralizing antibodies were demonstrated in sera of 61.5% of the animals examined. A comparative analysis of antibodies in NT and cell-ELISA method is presented. The role of BSMV in morbidity and mortality of seals (Phoca sibirica) is discussed.

Animals↗
PubMed1993

[Viral epizootic in the marine seal calf (Phoca vitulina) in 1988. Epidemiological aspects].

During the year 1988, an epizootic spread through European populations of harbour seals (Phoca vitulina). The first studies shed light on the importance of a new morbillivirus, close to canine distemper virus but different. However, other factors, like pollution by polychlorinated biphenyl (PCB) compounds may have played a part in the epizootic by increasing mortality. Up to then virology and pathology of wild populations of seals were not well known. This epizootic was an opportunity to learn about seal virus and their specificity, and to discover some biological and evolutionary implications of such a phenomenon.

Animals↗
PubMed1996

Impaired immunity in harbour seals [Phoca vitulina] fed environmentally contaminated herring.

In recent years, mass mortalities among seals and dolphins have been attributed to infections with different morbilliviruses. In all cases, these marine top predators were exposed to high levels of persistent lipophilic environmental contaminants accumulated through the food chain. This observation led to the hypothesis that a contaminant-related suppression of the immune system might have contributed to the severity of the virus outbreaks. We conducted a semi-field feeding experiment, in which we fed two groups of harbour seals (Phoca vitulina) fish with different levels of contaminants. During a period of 2 1/2 years, blood samples were taken at regular intervals, and the functioning of different compartments of the immune system was monitored and compared. We found impaired natural killer (NK) and specific T cell responses in the seals fed contaminated fish. This is the first demonstration of immunosuppression in mammals following chronic exposure to environmental contaminants at ambient environmental levels.

Animals↗
PubMedDate not supplied

[Physiological and biochemical characteristics of the blood of the Greenland seal, Pagophilus groenlandicus].

High hemoglobin concentration, rich hemoglobin supply of the body and high specific weight of the blood were found in harp seal cubs. The erythrocyte number is relatively low which agrees with our previous studies on aquatic and semi-aquatic mammals. Serum proteins from both adult and young harp seals are separated into 5-8 fractions during agar-agar gel electrophoresis. Diving of seals for considerable periods is partly accounted for by high hemoglobin and myoglobin concentrations adn also by perfect supply of the organism by these pigments.

Age Factors↗
PubMed2005

Selective death of lens epithelial cells using demineralized water and Triton X-100 with PerfectCapsule sealed capsule irrigation: a histological study in rabbit eyes.

BACKGROUND: Sealed irrigation of the capsular bag after removal of the cataractous lens isolates the interior of the capsular bag from the anterior segment, permitting isolated targeting of lens epithelial cells (LECs) in vivo using pharmacologic agents while minimizing the risk of damage to other intraocular structures. OBJECTIVES: To assess the ability to deliver a nonspecific, extremely toxic agent (Triton X-100) directly to the LECs after crystalline lens removal, and to assess the eyes histologically for evidence of collateral damage. METHODS: Twelve eyes from 6 New Zealand White rabbits were divided into 3 groups of 4 eyes that underwent phacoaspiration of the crystalline lens. Group 1 was a control. In group 2, the anterior segment was irrigated with Triton X-100 and demineralized water for injection for 5 minutes. In group 3, the lens capsule was isolated from the anterior segment using sealed capsule irrigation (SCI) with PerfectCapsule (Milvella Pty Ltd, Sydney, Australia). After surgery, the rabbits were humanely euthanized. The enucleated eyes were immediately fixed in 10% neutral buffered formalin, histological analysis was performed to assess the corneal endothelium, iris, and retina, and the capsular bag and residual equatorial LECs were assessed. RESULTS: The capsular bag was sealed and inflated under SCI in all treated eyes in group 3. Histological evaluation revealed no evidence of collateral damage in group 1 and group 3. Significant histological damage to the cornea, iris, and peripheral retina was noted in group 2. Histological evaluation of each capsular bag suggests presence of LECs in group 1 and group 2. In the presence of SCI, Triton X-100 caused almost complete destruction of LECs in the capsular bag. CONCLUSIONS: Results suggest that SCI allows selective delivery of toxic agents directly into the capsular bag, preventing collateral damage to surrounding intraocular structures. The PerfectCapsule device kept the capsular bag well inflated intraoperatively, which may allow the isolated, safe delivery of pharmacologic agents into the capsular bag during cataract surgery. Clinical Relevance Postoperative proliferation of LECs in the capsular bag remains the most frequent complication of cataract surgery. Unprotected intraocular infusion of cytotoxic drugs, antimetabolites, or hypo-osmotic agents during cataract surgery has the potential risk of causing toxic effects in corneal endothelium and adjacent intraocular tissues. Selective delivery of pharmacologic/hypo-osmotic agents into the capsular bag requires positive pressure inflation of the bag and is now possible using an SCI device. This device allows the surgeon to reseal the capsular bag intraoperatively, achieve positive pressure inflation of the capsular bag, and direct selective targeting of LECs.

Animals↗
PubMed1999

Kinetics of sealing for transient electropores in isolated mammalian skeletal muscle cells.

Permeabilization of the plasma membrane by electrical forces (electroporation) can be either transient or stable. Although the exact molecular mechanics have not yet been described, electroporation is believed to initiate primarily in the lipid bilayer. To better understand the kinetics of membrane permeabilization, we sought to determine the time constants for spontaneous transient pore sealing. By using isolated rat flexor digitorum brevis skeletal muscle cells and a two-compartment diffusion model, we found that pore sealing times (tau p) after transient electroporation were approximately 9 min. tau p was not significantly dependent on the imposed transmembrane potential. We also determined the transmembrane potential (delta Vm) thresholds necessary for transient and stable electroporation in the skeletal muscle cells. delta VmS ranging between 340 mV and 480 mV caused a transient influx of magnesium, indicating the existence of spontaneously sealing pores. An imposed delta Vm of 540 mV or greater led to complete equilibration of the intracellular and extracellular magnesium concentrations. This finding suggests that stable pores are created by the larger imposed transmembrane potentials. These results may be useful for understanding nerve and skeletal muscle injury after an electrical shock and for developing optimal strategies for accomplishing transient electroporation, particularly for gene transfection and cell transformation.

Animals↗
PubMed2000

Immediate sealing of arterial puncture sites after cardiac catheterization and coronary interventions: initial U.S. feasibility trial using the Duett vascular closure device.

The aim of this first U.S. feasibility study was to investigate the safety and efficacy of a novel vascular sealing device, Duett, following percutaneous endovascular procedures. Immediately following a catheterization procedure, the sealing device was deployed at the femoral arterial access site in 43 patients (diagnostic 29, intervention 11, intervention + abciximab 3). Patients were followed up at 1 month with clinical assessment, ankle-brachial index measurement, and Doppler ultrasound of the treated femoral artery puncture site. Successful hemostasis was achieved with the Duett alone in 42/43 (97.7%) patients. There was one uncomplicated crossover to manual compression. The time to hemostasis was 4.0+/-1.5, 6.9+/-4.2, and 5.8+/-1.2 min for diagnostic, interventional, and abciximab patients, respectively. At 1-month follow-up, one patient (2.3%) required ultrasound-guided compression for treatment of a pseudoaneurysm. There were no other major complications. This novel vascular sealing device appears to achieve rapid and safe hemostasis successfully immediately following a wide range of percutaneous endovascular procedures.

Adult↗
PubMed2001

Early clinical experience with the 6 French Angio-Seal device: immediate closure of femoral puncture sites after diagnostic and interventional coronary procedures.

The objective of this study was to assess the early safety and efficacy of the novel 6 Fr Angio-Seal device for routine clinical use after diagnostic cardiac catheterization and coronary angioplasty. In a prospective study, we used the 6 Fr Angio-Seal device in 180 consecutive patients (131 male, 49 female, mean age 60.7 years) for closure of femoral arterial puncture sites immediately after diagnostic (n = 108) or interventional (n = 72) coronary procedures independent of the coagulation status. All patients were monitored for 24 hr after the procedure and followed for 30 days. The closure device was successfully deployed in 95.4% after diagnostic catheterization versus 98.6% after coronary angioplasty (P = 0.963). Immediate hemostasis was achieved in 91.5% versus 90.1% of the patients (P = 0.993). Major complications were observed 1.9% versus 2.8% of the patients (P = 0.885). During 30-day follow-up, no late events or complications were reported. The 6 Fr Angio-Seal device is a safe and effective device that allows for immediate closure of femoral puncture sites after both diagnostic and interventional procedures with a low rate of major complications.

Adult↗
PubMed1993

Endoluminal sealing of vascular wall disruptions with radiofrequency-heated balloon angioplasty.

Suboptimal luminal widening or acute closure secondary to arterial dissection remain significant risks of percutaneous transluminal balloon angioplasty. Non surgical techniques are often employed in an attempt to repair dissections either as temporary or definitive treatment. The aim of this study was to test the hypothesis that radiofrequency thermal balloon angioplasty at an operating temperature of 70 degrees C and low inflation pressure could seal dissections and perforations in a model of severe arterial wall damage. Dissections and perforations were created in renal (n = 4) and carotid (n = 4) arteries in four mongrel dogs. Endoluminal sealing was then attempted with conventional balloon angioplasty or radiofrequency thermal balloon angioplasty (2 atm at 70 degrees C). Contrast dye extravasation persisted in all cases following conventional balloon angioplasty but completely resolved with radiofrequency balloon angioplasty in all but one artery. Histologic examination of the arteries treated with radiofrequency balloon angioplasty showed extensive thermal injury, including transmural coagulation necrosis, flattening of the internal elastic lamina, and medial thinning. On the basis of these results, the utility of thermal balloon angioplasty for endoluminal sealing of dissections and perforations complicating angioplasty deserves further evaluation.

Aortic Dissection↗
PubMed2005

Electrothermal bipolar vessel sealing system is a safe and time-saving alternative to classic suture ligation in total thyroidectomy.

BACKGROUND: Total thyroidectomy is associated with minimal morbidity. The electrothermal bipolar vessel sealing system is an adjunct to the surgical technique, recently made available to thyroid surgery. METHODS: This is a prospective randomized trial of total thyroidectomies performed in single unit from July 2003 to May 2004. Patients were randomly assigned in two groups: group A (n = 90), total thyroidectomy with the classic suture ligation technique; and group B (n = 94), total thyroidectomy with the use of the electrothermal bipolar vessel sealing system. RESULTS: Operative time was significantly reduced in group B by 14 minutes (mean difference, 14.3 +/- 4.2 minutes, 95% CI, 5.88-22.6 minutes). No statistically significant differences were found in postoperative complications, postoperative serum calcium measurements, or hospital stay between the two groups. CONCLUSIONS: The electrothermal bipolar vessel sealing system is a safe and useful, time-saving adjunct for total thyroidectomy.

Electrocoagulation↗
PubMed2003

Plasmalemmal sealing of transected mammalian neurites is a gradual process mediated by Ca(2+)-regulated proteins.

Cultured mammalian PC12 or B104 cells do not instantaneously restore a plasmalemmal barrier (seal) after neurite transection, as measured using fluorescent dye probes of various sizes and saline solutions with different [Ca(2+)](o). Rather, transected cells gradually (from 15 to 60 min postseverance) exclude probes (dye molecules) of progressively smaller size. Furthermore, an inhibitor (calpeptin) of a Ca(2+)-activated cysteine protease (calpain) and antibodies or toxins to a Ca(2+)-regulated protein (synaptotagmin) and other membrane fusion proteins (syntaxin and synaptobrevin) inhibit plasmalemmal sealing. These data obtained using molecular probes on mammalian cell lines are consistent with previous data on invertebrate giant axons indicating that Ca(2+) plays many roles in the formation, accumulation, and fusion/interaction of vesicles gradually forming a seal at a site of plasmalemmal damage.

Animals↗
PubMed2005

Analysis of organochlorines in harbor seal (Phoca vitulina) tissue samples from Alaska using gas chromatography/ion trap mass spectrometry by an isotopic dilution technique.

A gas chromatography/ion trap mass spectrometry (GC/ITMS) method was developed for the determination of organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs) and polychlorinated naphthalenes (PCNs) in harbor seal (Phoca vitulina) tissues. Tissue samples were homogenized, lyophilized and fortified with (13)C-PCBs 28, 123, 169 and 170, and then extracted with an accelerated solvent extractor with a mixture of hexane and methylene chloride (1:1, v/v). After lipid removal using a 40% H(2)SO(4)-modified silica gel column, all organochlorines were collected in one fraction and further fractionated with an activated carbon/silica gel (1:20) column into a first fraction containing OCPs, non-coplanar PCBs and (13)C-PCBs 28, 123 and 170, and a second containing PCNs, coplanar PCBs and (13)C-PCB 169. Prior to GC/MS/MS analysis, (13)C-PCB 169 was added into the first fraction as an injection standard and (13)C-PCB 170 into the second fraction to calibrate the recoveries of the fortified internal standards. This method can effectively eliminate matrix interferences, and has high selectivity and sensitivity. Recoveries averaged 45-86% for OCPs with relative standard deviations (RSDs) of 2-14%, 52-137% for PCBs with RSDs of 3-29% and 36-152% for PCNs with RSDs of 7-29% from lard and chicken heart samples, which were used as alternative matrices to harbor seal samples in recovery studies. The limits of detection for OCPs, PCBs and PCNs were 0.7-1.9, 1.5-8.9 and 0.5-10 pg/g dry weight, respectively. This method can be used to analyze OCPs, PCBs and PCNs in harbor seal blubber, liver and kidney samples.

Alaska↗
PubMed1997

Balancing foraging and reproduction in the male harbour seal, an aquatically mating pinniped

Aquatically mating male harbour seals, Phoca vitulinamust balance the competing demands of foraging and reproduction while at sea during the breeding season. Time-depth recorders (TDRs) were attached to 31 adult male harbour seals to investigate changes in diving behaviour at Sable Island, Nova Scotia, during the 1992-1994 breeding seasons. Male seals were captured, fitted with TDRs and weighed at the beginning of the season in late May, then recaptured for TDR removal and reweighing at the end of June. Males made deep dives (to maximum depths >20 m) more frequently early in the breeding season, then switched to shallow (</=20 m) diving later during the mating period. Deep dives (38.8&plusmn;2.2 m; 4.6&plusmn;0.1 min) were fairly uniform in shape, appearing flat-bottomed with rapid rates of descent and ascent and long bottom time, but shallow dives (10.5&plusmn;0.5 m; 3.0&plusmn;0.1 min) were more variable in shape. Rates of mass loss varied inversely with time spent in deep dives, indicating that deep diving behaviour reflects foraging activity. Males lost mass while making shallow dives associated with mating behaviour later in the breeding season. Deep diving occurred more frequently during daylight hours. Shallow dives were predominant at twilight and at night when females are likely to be departing and returning to the island from foraging trips in late lactation. At Sable Island, males may maximize their encounter rates with oestrous females by ceasing to make offshore foraging trips, and increasing the time spent patrolling home ranges and displaying in shallow water near the breeding colony in late lactation. Relatively larger males may have a competitive advantage since they can afford to spend less time making foraging trips away from the concentration of females and more time displaying in shallow water near the shore.1997The Association for the Study of Animal Behaviour

Journal Article↗
PubMed2001

Mother-Offspring vocal recognition in northern fur seals is mutual but asymmetrical.

During the 4-month period of offspring dependence, northern fur seal, Callorhinus ursinus, mothers and pups use a well-developed multimodal recognition ability to routinely find one another within large and dense breeding aggregations. I studied the vocal/auditory aspect of this ability to look at operational differences between the two members of a recognition dyad. If parent-offspring conflict theory is applied to animal communication behaviour, we should expect unequal selective forces acting on parents and offspring. In northern fur seal maternal recognition dyads, I expected pups to expend more energy in the reunion process because they carry the greater burden of a failed reunion. Furthermore, in terms of signal detection theory, pups should have a lower rejection threshold (lower bias) than mothers. To address these questions, I conducted vocal playback experiments and behavioural observations on a natural population of northern fur seals in the Pribilof Islands, Alaska, U.S.A. Although playback results support mutual vocal recognition, pups were both more vocally responsive and made more recognition errors (i.e. false alarms). Behavioural observations, including search time, distance travelled, signalling behaviour and contact with nonoffspring show that pups expend more effort in the reunion process. These findings are consistent with expectations and begin to quantify how selection pressure on recognition behaviour can vary at different stages of development. Copyright 2001 The Association for the Study of Animal Behaviour.

Journal Article↗