SEARCH · PubMed Health

Results for “Seals, Earless”

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 91 records · Page 5Linked to original sources

PubMed1987

Smooth muscle and myofibroblast-like cells in the perimedullary stromal basket of kidneys from ringed seals (Phoca hispida).

The medullary pyramid of renculi in kidneys of ringed seals (Phoca hispida) is enclosed by a basket composed of ribbons of stromal tissue continuous with the wall of the calyx. Branched smooth muscle cells with well-developed Golgi complexes and rough endoplasmic reticulum and only an incomplete external lamina are the principal cells in sites near the origin of the ribbons from the calycal wall. Deeper in the corticomedullary junctional region, smooth muscle is progressively replaced with stellate or spindle-shaped cells exhibiting structural characteristics intermediate between those of fibroblasts and smooth muscle fibers. These myofibroblast-like cells contain arrays of parallel microfilaments 6-8 nm thick with associated focal densities and subplasmalemmal dense plaques, caveolae, elongate, often deeply wrinkled nuclei, and well-developed Golgi complexes and rough endoplasmic reticulum. Material resembling external lamina is associated with parts of the surfaces of most myofibroblast-like cells and intermediate junctions are present. Fibroblasts lacking arrays of parallel microfilaments are a minority at any level in the stromal ribbons. Interstitial cells in the vicinity of the corticomedullary junction show similar myofibroblast-like characteristics. The smooth muscle and myofibroblast-like cells presumably assist expression of urine from the papilla and calyx, and possibly participate as pacemakers for the urinary tract.

Animals↗

PubMed1976

Structure of the adenohypophysis in juvenile harp seal, Pagophilus groenlandicus.

A study was made of the morphology of the adenohypophysis in immature harp seals and the fine structure of cellular components of the pars tuberalis, pars intermedia and pars distalis was described. The pars intermedia composed 8-15% of the hypophysis and contained colloid filled vesicles similar to those found in the other mammalian species. The pars distalis cells were grouped into more or less well defined regions, thus facilitating the correlation of cellular identification from both light and electron micrographs. Five chromophilic cell types were tentatively identified, one acidophil (putative somatotroph), four basophils (3 putative gonadotrophs and one cell type with the characteristics of both corticotrophs and thyrotrophs) and non-granulated "stellate" cells. The absence of a positive prolactin cell identification was thought to be due to the immaturity of the seals used in the study.

Animals↗

PubMed1978

Structure of the Adenohypophysis in parturient female and neonate harp seals, Pagophilus groenlandicus.

The pars distalis of parturient harp seals (Pagophilus groenlandicus) is divisible into three distinct zones based on the major cellular components of the different regions. A clear zonation is lacking in neonate seals, the medical "basophilic wedge" and the anterior gonadotrophic were small and difficult to identify. Five cell types were identified based on cytological characteristics: somatotrophs, mammotrophs, thyrotrophs, gonadotrophs and stellate cells; corticotrophs could not be identified, with any certainty, in any of the preparations, nor could the gonadotrophs be classified into LH, FSH, and ICSH cells. The pars intermedia enlarged during the early post-partum period and was large in the parturient females.

Adrenocorticotropic Hormone↗

PubMed1993

Toxic potential of non-ortho and mono-ortho coplanar polychlorinated biphenyls in Aroclors, seals, and humans.

Mono-ortho and non-ortho coplanar polychlorinated biphenyls (PCBs) were analyzed in Aroclors, seals, and humans by graphitized carbon, a recently developed HPLC method (Hong et al. 1992b) and high-resolution gas chromatography with electron capture detection (HRGC/ECD). The concentration data were multiplied by potency factors derived from aryl hydrocarbon hydroxylase (AHH) induction to give 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) equivalents. The ability to separate coplanar PCBs from the majority of PCBs has allowed the use of TCDD toxicity equivalence to compare the relative dioxin-like potency of PCB residues in the complex mixtures. The most active mixtures, Aroclors 1254, 1248, and 1242, contained 42-54% by weight of chlorine. The results demonstrate that the apparent dioxin-like potency of PCB residues in Aroclors, seals, and humans is dominated by three congeners, 3,3',4,4'-tetra-, 2,3,3'-4,4'-, and 3,3',4,4',5-pentachlorobiphenyl (IUPAC nos. 77, 105, 126).

Adipose Tissue↗

PubMed1988

Protective metabolic mechanisms during liver ischemia: transferable lessons from long-diving animals.

During periods of O2 lack in liver of seals, mitochondrial respiration and adenosine triphosphate (ATP) synthesis are necessarily arrested. During such electron transfer system (ETS) arrest, the mitochondria are suspended in functionally protected states; upon resupplying O2 and adenosine diphosphate (ADP), coupled respiration and ATP synthesis can resume immediately, implying that mitochondrial electrochemical potentials required for ATP synthesis are preserved during ischemia. A similar situation occurs in the rest of the cell since ion gradients also seem to be maintained across the plasma membrane; with ion-specific channels seemingly relatively inactive, ion fluxes (e.g., K+ efflux and Ca++ influx) can be reduced, consequently reducing ATP expenditure for ion pumping. The need for making up energy shortfalls caused by ETS arrest is thus minimized, which is why anaerobic glycolysis can be held in low activity states (anaerobic ATP turnover rates being reduced in ischemia to less than 1/100 of typical normoxic rates in mammalian liver and to about 1/10 the rates expected during liver hypoperfusion in prolonged diving). As in many ectotherms, an interesting parallelism (channel arrest coupled with a proportionate metabolic arrest at the level of both glycolysis and the ETS) appears as the dominant hypoxia defense strategy in a hypoxia-tolerant mammalian organ.

Animals↗

PubMed1979

Structure of the testis in neonate and adult harp seals, Pagophilus groenlandicus.

The structure of the seminiferous tubules in neonate harp seals, Pagophilus groenlandicus, was essentially similar in one-, five- and ten-day old animals. The tubules were small in diameter, devoid of lumina and contained predominantly supportive cells. The interstitial cells in the neonates were large, numerous and highly vacuolated. They became smaller and appeared less active in the ten-day old animals compared with the one-day old seals, although they were still considerably more numerous and vacuolated than in testes taken from adult harp seals.

Aging↗

PubMed1990

Cardiac output and stroke volume in swimming harbor seals.

Cardiac output was measured by the thermodilution method in three young harbor seals, at rest and while swimming up to the maximum effort for which they could be trained. Stroke volume was determined by counting heart rate simultaneously with determination of cardiac output. Cardiac outputs varied widely between surface breathing (7.8 ml.kg-1.s-1) and breath-holding while swimming under water (1.8 ml.kg-1.s-1). Stroke volume while at the surface was almost twice the volume while submerged. Surface cardiac output was always near maximal despite work effort, whereas submerged cardiac output gradually increased at higher work efforts. The cardiovascular performance of seals at the maximum MO2 we could induce from them is equivalent to that of the domestic goat.

Animals↗

PubMed1990

Circulatory water concentration in suckling and fasting northern elephant seal pups.

This study examined circulatory water concentrations in the neonatal northern elephant seal (Mirounga angustirostris) in order to determine how suckling and fasting would alter the percentage of water in the whole blood, plasma, and red blood cells (RBC). Plasma water concentration dropped by about 3% during suckling and recovered about 1% during the fast (92.38 +/- 0.48% less than 1 week old, 90.15 +/- 0.36% weaning, 91.02 +/- 0.68% end of fast). RBC water values during this time were more variable than plasma values: RBC water increased about 1% during the first 2 weeks of suckling (from 67.80 +/- 0.28% to 68.68 +/- 0.51%) but dropped to slightly below original neonatal values by weaning (67.15 +/- 0.63%). The first several weeks of fasting were marked by wide variability in RBC water, but by the end of the fast RBC water was comparable to that at weaning. These results indicate: 1) Northern elephant seal pups do not exhibit circulatory dehydration during 10 weeks of fasting; 2) Measurements of plasma or RBC metabolites (such as plasma glucose or RBC hemoglobin) may show variations or trends due not to metabolic regulation but rather to changes in circulatory water concentration.

Age Factors↗

PubMed1995

Prenatal and postnatal transfer of fatty acids from mother to pup in the hooded seal.

Unlike most mammals, hooded seal (Cystophora cristata) pups are born with a substantial layer of adipose tissue. Subsequently, during the brief lactation period of only 4 days, fasting mothers mobilize enormous amounts of lipid from blubber and secrete milk (60% fat) at rates of 10 kg.day-1. Pups gain 7 kg.day-1 due primarily to the deposition of fat in blubber. We measured blubber content and fatty acid composition of blubber and milk in hooded seal mother-pup pairs at birth and over the 4-day lactation period to examine the nature and source of fetal lipids, the incorporation of maternal blubber fatty acids into milk lipid, and patterns of fatty acid deposition in suckling young. The fatty acid composition of the blubber of the newborn was notably different from that of its mother. Fetal deposition was likely due to a combination of both fetal synthesis and direct placental transfer of maternal circulating fatty acids. The blubber of the newborn was characterized by high levels (> 90% of total fatty acids) of saturated and monounsaturated fatty acids of primarily endogenous origin. In particular, the fetus appeared to have high delta-9 desaturase activity as evidenced by the large amounts of 14:1n-5 (4.2%) and 16:1n-7 (37.0%) in newborn blubber compared to maternal blubber (0.2% and 14.1%, respectively). Nevertheless, essential and long-chain polyunsaturated fatty acids of the n-3 and n-6 families, which could only have originated by direct transfer from the mother, comprised > 7% of pup blubber fatty acids and indicated greater rates of placental transfer than found in humans. In hooded seal mothers, rapid lipid transfer during the brief lactation period appeared to be facilitated by direct incorporation of mobilized fatty acids into milk. Although some differences in proportions of specific fatty acids were found between milk and maternal blubber, most of these differences declined over the course of lactation. However, selective mobilization of 20:5n-3 from maternal blubber into milk was apparent throughout lactation and resulted in elevated levels in pup blubber at weaning compared to maternal blubber. Ingested fatty acids were deposited directly and without modification into the blubber of pups, and by 4 days the fatty acid composition of pup blubber was virtually identical to that of the milk consumed.

Animals↗

PubMed1993

Water conservation and protein metabolism in northern elephant seal pups during the postweaning fast.

Urine production and N output were monitored in northern elephant seal (Mirounga angustirostris) pups progressing through 10 weeks of a natural postweaning fast. Urine output declined by 84% (to 69 +/- 12 ml.day-1) at 10 weeks (P < 0.05). Glomerular filtration rate at 10 weeks was 51% of the 67 +/- 3 ml serum.min-1 observed during week 1 (P < 0.05). Urine N excretion fell by 69% to 1.2 +/- 0.17 g.day-1, while urinary concentration increased (P < 0.05). Serum urea declined from an initial 11 mmol.l-1 to 5-7 mmol.l-1 by 5 weeks. The fall in urinary N loss (and thus amino acid oxidation) was concomitant with depressed metabolic rate. Therefore, protein contributed little toward meeting energy demands (i.e., < 4% of average metabolic rate) throughout fasting. These data indicate that fasting pups improve water conservation and minimize protein catabolism during prolonged natural fasts without an exogenous source of water.

Animals↗

PubMed1994

The effect of feeding on the metabolic rate in harbour seals (Phoca vitulina).

The heat increment of feeding was estimated in harbour seals (Phoca vitulina). Seals were given different amounts of herring, ranging from 0.8 to 2.65 kg. The caloric content of the herring ranged from 6575 to 12560 kJ.kg-1 depending on time of year. Metabolic rate increased within 30 min after feeding, and the magnitude and duration of heat increment of feeding depended on the size of the meal and the caloric content of the herring. Measured heat increment of feeding was up to 14.9% of gross energy intake and metabolic rate increased as much as 46% above resting, postabsorptive metabolic rate for 15 h duration in a harbour seal with a body weight of approximately 40 kg.

Animals↗

PubMed1993

Activity, milk intake and energy consumption in free-living ringed seal (Phoca hispida) pups.

Measurements of growth, activity and energy consumption and estimates of milk intake were made in free-living, nursing ringed seal (Phoca hispida) pups. This was accomplished through the simultaneous use of time-depth recorders and the doubly labelled water technique. The pups spent an average of 52 +/- 7% of their time hauled out on the ice, 37 +/- 5% of the time in the water at the surface, and 11 +/- 5% of the time diving. Average daily mass gain of the pups (n=3) throughout the duration of the study period was 0.35 +/- 0.08 kg. The composition of the mass gain was 76% fat, 6% protein, and 18% water. The total water flux was measured to be 52 +/- 10 ml.kg-1.day-1. Average CO2 production was 0.85 +/- 0.16 ml.g-1.h-1, corresponding to a field metabolic rate of 0.55 +/- 0.10 MJ.kg-1.day-1, or 3.8 +/- 0.6 times the predicted basal metabolic rate based on body size (Kleiber 1975). Average daily milk intake was estimated to be 1379 +/- 390 ml. The field metabolic rate for the different components of seal pup activity budgets were calculated to be FMRhaul out = 1.34 BMR, FMRsurface = 6.44 BMR, and FMRdiving = 5.88 BMR.

Animals↗

PubMed1995

Lipoprotein lipase activity and its relationship to high milk fat transfer during lactation in grey seals.

Lipoprotein lipase regulates the hydrolysis of circulating triglyceride and the uptake of fatty acids by most tissues, including the mammary gland and adipose tissue. Thus, lipoprotein lipase is critical for the uptake and secretion of the long-chain fatty acids in milk and for the assimilation of a high-fat milk diet by suckling young. In the lactating female, lipoprotein lipase appears to be regulated such that levels in adipose tissue are almost completely depressed while those in the mammary gland are high. Thus, circulating fatty acids are directed to the mammary gland for milk fat production. Phocid seals serve as excellent models in the study of lipoprotein lipase and fat transfer during lactation because mothers may fast completely while secreting large quantities of high fat milks and pups deposit large amounts of fat as blubber. We measured pup body composition and milk fat intake by isotope (deuterium oxide) dilution and plasma post-heparin lipoprotein lipase activity in six grey seal (Halichoerus grypus) mother-pup pairs at birth and again late in the 16-day lactation period. Maternal post-heparin lipoprotein lipase activity increased by an average of four-fold by late lactation (P = 0.027), which paralleled an increase in milk fat concentration (from 38 to 56%; P = 0.043). Increasing lipoprotein lipase activity was correlated with increasing milk fat output (1.3-2.1 kg fat per day) over lactation (P = 0.019). Maternal plasma triglyceride (during fasting) was inversely correlated to lipoprotein lipase activity (P = 0.027) and may be associated with the direct incorporation of long-chain fatty acids from blubber into milk. In pups, post-heparin lipoprotein lipase activity was already high at birth and increased as total body fat content (P = 0.028) and the ratio of body fat: protein increased (P = 0.036) during lactation. Although pup plasma triglyceride increased with increasing daily milk fat intake (P = 0.023), pups effectively cleared lipid from the circulation and deposited 70% of milk fat consumed throughout lactation. Lipoprotein lipase may play an important role in the mechanisms involved with the extraordinary rates of fat transfer in phocid seals.

Animals↗

PubMed1995

Milk intake, growth and energy consumption in pups of ice-breeding grey seals (Halichoerus grypus) from the Gulf of St. Lawrence, Canada.

In this study we document growth, milk intake and energy consumption in nursing pups of ice-breeding grey seals (Halichoerus grypus). Change in body composition of the pups, change in milk composition as lactation progresses, and mass transfer efficiency between nursing mothers and pups are also measured. Mass transfer efficiency between mother-pup pairs (n = 8) was 42.5 +/- 8.4%. Pups were gaining a daily average of 2.0 +/- 0.7 kg (n = 12), of which 75% was fat, 3% protein and 22% water. The total water influx was measured to be 43.23 +/- 8.07 ml.kg-1.day-1. Average CO2 production was 0.85 +/- 0.20 ml.g-1.h-1, which corresponds to a field metabolic rate of 0.55 +/- 0.13 MJ.kg-1.day-1, or 4.5 +/- 0.9 times the predicted basal metabolic rate based on body size (Kleiber 1975). Water and fat content in the milk changed dramatically as lactation progressed. At day 2 of nursing, fat and water content were 39.5 +/- 1.9% and 47.3 +/- 1.5%, respectively, while the corresponding figures for day 15 were 59.6 +/- 3.6% fat and 28.4 +/- 2.6% water. Protein content of the milk remained relatively stable during the lactation period with a value of 11.0 +/- 0.8% at day 2 and 10.4 +/- 0.3% at day 15. Pups drank an average of 3.5 +/- 0.9 kg of milk daily, corresponding to a milk intake of 1.75 kg per kg body mass gained. The average daily energy intake of pups was 82.58 +/- 19.80 MJ, while the energy built up daily in the tissue averaged 61.72 +/- 22.22 MJ.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1989

Keratinophilic fungi isolated from Antarctic soil.

In the present study, 10 soil samples were collected aseptically from an equal number of areas of the Antarctic in the zone occupied by the 1986-1987 Italian expedition for research on keratinophilic fungi. Of particular interest was the isolation of a pathogenic fungus, Microsporum gypseum, from two sites in the base camp occupied by men and by skuas. Trichophyton terrestre was isolated from a site in which people worked and through which penguins and skuas passed. The most widespread fungal species were members of the genus Chrysosporium. Some of these species were isolated but not identified and this part of the study was still be completed. Another significant finding was the absence of fungi in one sample, while in another the widespread and abundant growth in all the seeded dishes of a single species of Chrysosporium. Other species in genera of general diffusion in many environments were also isolated: Aspergillus spp., Malbranchea sp., Mycelia sterilia spp., Paecilomyces sp., Penicillium spp. and Scopulariopsis spp.

Animals↗

PubMed1991

Fuel homeostasis in the harbor seal during submerged swimming.

1. The turnover rates and oxidation rates of plasma glucose, lactate, and free fatty acids (FFA) were measured in three harbor seals (average mass = 40 kg) at rest or during voluntary submerged swimming in a water flume at 35% (1.3 m.s-1) and 50% (2 m.s-1) of maximum oxygen consumption (MO2max). 2. For seals resting in water, the total turnover rates for glucose, lactate, and FFA were 23.2, 26.2, and 7.5 mumols.min-1.kg-1, respectively. Direct oxidation of these metabolites accounted for approximately 7%, 27%, and 33% of their turnover and 3%, 7%, and 18% of the total ATP production, respectively. 3. For swimming seals, MO2max was achieved at a drag load equivalent to a speed of 3 m.s-1 and averaged 1.85 mmol O2.min-1.kg-1, which is 9-fold greater than resting metabolism in water at 18 degrees C. 4. At 35% and 50% MO2max, glucose turnover and oxidation rates did not change from resting levels. Glucose oxidation contributed about 1% of the total ATP production during swimming. 5. At 50% MO2max, lactate turnover and anaerobic ATP production doubled, but the steady state plasma lactate concentration remained low at 1.1 mM. Lactate oxidation increased 63% but still contributed only 4% of the total ATP production. Anaerobic metabolism contributed about 1% of the total ATP production at rest and during swimming. 6. The plasma FFA concentration and turnover rate increased only 24% and 37% over resting levels, respectively, at 50% MO2max. However, the oxidation rate increased almost 3.5-fold and accounted for 85% of the turnover.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗

PubMed1996

Molecular cloning and sequencing of interleukin 6 cDNA fragments from the harbor seal (Phoca vitulina), killer whale (Orcinus orca), and Southern sea otter (Enhydra lutris nereis).

Using polymerase chain reaction, interleukin-6 (IL-6) cDNA fragments from harbor seal (Phoca vitulina), killer whale (Orcinus orca), and Southern sea otter (Enhydra lutris nereis) were cloned and sequenced. For all three species, a continuous open reading frame encoding 203 residues for harbor seal, 199 residues for killer whale, and 201 residues for sea otter with stop codons located at analogous positions were identified. These fragments correspond to nucleotides 71 - 753 of the human IL-6 transcript and represent 96% of the complete coding nucleotides. Comparison of these marine mammal sequences with other published mammalian IL-6 cDNA demonstrated that both harbor seal and sea otter IL-6 had most similarity to that of other terrestrial carnivores (Mustelidae and Canidae), while killer whale had highest identity with ruminants (Bovidae and Ovidae). Among the three marine mammal species characterized, as well as cDNA sequences from nine other species, 40 invariant amino acids, including a number of residues situated at the putative gp80 and gp130 receptor binding sites, were identified. The presence of invariant amino acids within the receptor-binding portion of IL-6 for twelve different species suggests these positions are essential for biological activity of IL-6 and, moreover, likely account for the cross-reactivity among different mammalian IL-6-like activities in mouse bioassays. An additional significant finding was the presence of several variant residues only within the mouse putative IL-6 receptor binding region, which may account for observations of restricted cross-reactivity of mouse IL-6-like activity in human bioassays. Together, these findings provide insights into the evolution of the mammalian IL-6 gene and additional valuable information regarding amino acid residues essential for the biological activity of mammalian IL-6.

Amino Acid Sequence↗

PubMed1989

The eye of the hooded seal, Cystophora cristata, in air and water.

Multiple refractive state measurements were made on a male and female hooded seal (Cystophora cristata) when the eyes were exposed to air and to water. The measures, made by conventional retinoscopy and by photorefraction, show that the seals are moderately hyperopic (2-3 diopters) in water and moderately myopic (2-4 diopters) in air. No significant astigmatism was noted in either medium. The absence of refractive state variation over time suggests that an accommodative mechanism is insignificant or absent, although histological study indicates that the ciliary muscle is well developed. Photokeratoscopy, carried out on two animals with two keratoscopic instruments, show that the cornea is relatively flat (30 mm, or about one-half the diameter of the eye). Furthermore the cornea is only slightly astigmatic (less than 1 diopter). The refractive power of the external corneal surface (in air), calculated from a measurement of corneal refractive index of 1.378, amounts to only 10 or 11 diopters. As in the typical fish eye, hooded seal lenses are spherical or nearly spherical in shape (24-23 mm), and have short focal lengths (30-32 mm). Focal measures for rays at varying distances from the lens center indicate that spherical aberration is well corrected. There is no indication in this seal species, of a previously reported adaptation involving a highly astigmatic cornea which together with a slit pupil can minimize the optical effect of movement from water to air.

Air↗