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At least 55 records · Page 3Linked to original sources

PubMed1999

Sealing properties of mechanical seals for an axial flow blood pump.

A miniature intraventricular axial flow blood pump for left ventricular support is under development. One of the key technologies required for such pumps is sealing of the motor shaft. In this study, to prevent blood backflow into the motor side, mechanical seals were developed and their sealing properties investigated. In the experimental apparatus, the mechanical seal separated the bovine blood on the chamber side from the cooling water on the motor side. A leakage of the blood was measured by inductively coupled plasma (ICP) light emission analysis. The rate of hemolysis was measured by the cyanmethemoglobin method. Frictional torque acting on the shaft was measured by a torque transducer. In the experiments, the rotational speed of the shaft was changed from 1,000 to 10,000 rpm, and the contact force of the seal faces was changed from 1.96 to 4.31 N. To estimate lubrication regimes, the Stribeck curve, a diagram of the coefficient of friction against the bearing characteristic G number, was drawn. The results of the experiments showed that both the leakage of blood and the rate of hemolysis were very small. The friction loss was also very small. The mechanical seal was operated in various lubrication regimes, from a fluid lubrication regime to a mixed lubrication regime.

Animals↗

PubMed1997

Histological, histochemical, and fine structural observations on the lymph node of the common seal (Phoca vitulina) and the grey seal (Halichoerus grypus).

BACKGROUND: The recent seal death epizootic prompted interest in their immune system, for which no current morphological data were available. METHODS: Lymph nodes from adult harbor seals (Phoca vitulina) and grey seals (Halichoerus grypus) were investigated by light microscopy, electron microscopy, and lectin histochemistry. RESULTS: No significant differences in the lymph node morphology were found between the two species, and the overall organization of the nodes comprises of capsule, trabeculae, cortex, paracortex, and medulla. Capsule and trabeculae are composed of tightly packed collagen and elastic fibrils and are rich in fibroblasts, myofibroblasts, and smooth muscle cells. Unmyelinated nerve fibers are common. The cortex contains numerous secondary follicles with well-developed germinal centers and paracortical areas with high endothelial venules. Antigen-presenting cells and phagocytic macrophages were abundantly present. The medullary cords contain numerous plasma cells. Fibroblastic reticulum cells are common throughout the parenchyma and transverse the sinus. Marginal, radial, and medullary sinuses are lined by littoral cells. The visceral lining of the sinuses is marked by macrophages and by numerous mast cells. CONCLUSIONS: The morphology of seal lymph nodes does not differ significantly from that of terrestrial mammals. Earlier functional conclusions concerning seal lymph nodes are substantiated by this morphological study.

Animals↗

PubMed1978

Arteriovenous anastomoses in the skin of seals. II. The California sea lion Zalophus californianus and the northern fur seal Callorhinus ursinus (Pinnipedia: Otariidae).

The structure, distribution and density of arteriovenous anastomoses (AVAs) were studied in body and flipper skin of a California sea lion and a nothern fur seal. In both animals AVAs consisted of arterial, intermediate and venous segments, and were generally larger and more tortuous in the sea lion than in the fur seal. In the sea lion the majority of AVAs (72%) occurred in the deeper region of the dermis, and the density was significantly greater in the flippers than in the body. In the northern fur seal most AVAs (76%) occurred in the superficial region of the dermis; the density of AVAs in flipper skin was significantly higher than in body skin, and the density in the hind flipper was significantly greater than in the foreflipper. Arteriovenous anastomoses are important in the regulation of body temperature in seals; when these animals are on land, AVAs function to dissipate body heat, and vascular thermoregulation occurs in the flippers but notover the general body surface. Due to differences in distribution and density, AVAs play a more significant role in thermoregulation in the northern fur seal than in the California sea lion.

Animals↗

PubMed2001

Melatonin potentiates the vasoconstrictive effect of noradrenaline in renal artery from newborn hooded seals (Cystophora cristata) and harp seals (Phoca groenlandica).

Isometric tension was recorded by force displacement transducers in ring segments of the inferior branch of the renal artery from newborn hooded seals (Cystophora cristata, n=6), harp seals (Phoca groenlandica, n=3) and domestic pigs (Sus scrofa f. domestica, n=5). Arterial segments were mounted in heated organ baths and exposed to graded concentrations of noradrenaline (NA) and adrenaline (A), alone or together with melatonin. The melatonin concentration in the bath was similar to the plasma concentration normally found in each experimental animal. Melatonin alone did not affect the tension in any of the species, but melatonin potentiated the contraction induced by NA in hooded and harp seal arteries to a maximum of about 25% above the resting, pre-stretch level. The selective melatonin receptor antagonist luzindole reduced this potentiation by 80%. Species-specific concentrations of melatonin did not potentiate the NA-effect in the domestic pig or the A-induced contraction in any of the species. The results indicate that melatonin specifically increases the NA-sensitivity of smooth muscles in renal arteries from newborn seals. It is presumed that similar effects may operate in foetal and maternal seals and may influence their circulation during maternal diving.

Animals↗

PubMed1976

[Histology and histochemistry of the seal ovaries and the age-related changes in the ovaries of the Greenland seal].

Histological and histochemical methods were used to study the ovaries of Greenland seal (Pagophoca groenlandica) from birth-time up to 30 years of age and mature females of Phoca vitulina and Erignathus barbatus. The ovary of the new-born Greenland seal has fetal medullary substance which is a provisory endocrinous gland producing not only sex hormones but also corticosteron. In other species of seals the intestinal cells of the medullary substance are the equivalent of this gland. Within 3-4 weeks after birth the reduction of the fetal medullary substance is completed, it is substituted by the connective tissue and the ovary acquires its typical structure. The rest of the fetal medullary substance is in the depth of the cortex and near the infundibulum of the ovary as lipofuscincontaining cells. When the maturation period approaches, the process of the follicle atresia regularly changes: the epithelium dies quicker, and the multiplication of intestinal cells increases. The ovaries of seals are rich in interstitial cells. Their amount cyclically changes. The cells producing steroid hormones always well hydrolize AS naphthyl-phosphates, the reaction with glycerophosphate is more variable. The connective tissue is poor in acid mucopolysaccharides, its amorphous substance in the ovary cortex is rich in protein. Senile changes of the ovary are noticed in the seal beginning from 20 years of age.

Age Factors↗

PubMed2001

Organochlorine pesticides, polychlorinated biphenyls, and butyltin compounds in blubber and livers of stranded California sea lions, elephant seals, and harbor seals from coastal California, USA.

Concentrations of polychlorinated biphenyls (PCBs), DDTs (p,p'-DDE, p,p'-DDD, p,p'-DDT), chlordanes (CHLs; cis-chlordane, cis-nonachlor, trans-nonachlor, and oxychlordane), hexachlorocyclohexane isomers (HCHs), hexachlorobenzene (HCB), tris(4-chlorophenyl)methane (TCPMe), tris(4-chlorophenyl)methanol (TCPMOH), and mono- (MBT), di-(DBT), and tri-butyltin (TBT) were determined in blubber and livers of 15 California sea lions (Zalophus californianus), 6 northern elephant seals (Mirounga augustirostris), and 10 harbor seals (Phoca vitulina) found stranded along the coasts of California, USA, during 1991-1997. Among the organochlorines analyzed, DDTs were predominant, followed in decreasing order by PCBs, CHLs, TCPMe, TCPMOH, HCHs, and HCB. The greatest concentrations of organochlorines were found in California sea lions. The highest DDT and PCB concentrations found in the blubber of California sea lions were 2,900 and 1,300 microg/g, lipid weight, respectively. Concentrations of TCPMe and TCPMOH in California sea lions were correlated significantly with DDT concentrations. Concentration ratios of various organochlorines in harbor seal livers were different from those in California sea lions and elephant seals, which suggested that the sources of exposure of harbor seals to organochlorines were different from those in the other two species. Concentrations of butyltin compounds in livers of pinniped species ranged from 2 to 99 ng/g, wet weight, which were less than those observed in cetaceans and in California sea otters.

Adipose Tissue↗

PubMed2004

Sealing ability of One-Up Bond and MTA with and without a secondary seal as furcation perforation repair materials.

This study investigated the ability of One-Up Bond alone and mineral trioxide aggregate (MTA), with and without a secondary seal of One-Up Bond or SuperEBA to seal saucer-shaped perforation defects in human molars. Cusps were removed, roots were amputated, and endodontic therapy completed on 40 extracted teeth. A cylindrical hole was made in each tooth from the furcation area to the chamber, into which a section of steel tubing was cemented. Intracoronal saucer-shaped defects were created over the perforation. The teeth were restored with MTA, One-Up Bond, or MTA with a secondary seal of One-Up Bond or SuperEBA. The integrity of the seal was evaluated by fluid filtration. MTA alone leaked significantly more than One-Up Bond or MTA with either secondary seal at 24 h. At 1 month, MTA, MTA plus One-Up Bond, and One-Up Bond alone were equivalent.

Aluminum Compounds↗

PubMed1992

Fatty-acyl esters of retinol (vitamin A) in the liver of the harp seal (Phoca groenlandica), hooded seal (Cystophora cristata), and California sea lion (Zalophus californianus).

The fatty-acid composition of retinyl esters in the livers of two species of phocid seal, the harp seal (Phoca groenlandica, n = 20) and the hooded seal (Cystophora cristata, n = 15), and one species of otariid seal, the California sea lion (Zalophus californianus, n = 6), was determined. Vitamin A ranged in concentration from 4 to 1024 nmol retinol/g liver for the phocids and from 381 to 979 nmol/g liver for the otariids. In most of the livers, retinyl palmitate was not the principal ester, and the palmitate + stearate + oleate trio of retinyl esters represented less than 50% of the total. In all samples, the retinyl esters contained 20:1, 20:4, 20:5, and 22:6 in unusually large amounts. Retinyl esters tended to be richer than whole-liver lipids in 20:5 + 22:6, whereas whole-liver lipids were richer in 18:0 and 18:2. Therefore, the pool of acyl donors used for the esterification of retinol may be distinct from that used for other lipids. Birth-to-weaning changes were seen only in the harp seals. In the pups, the hepatic vitamin-A concentration increased 454%, while the proportion of 18:0 and 20:1 in the retinyl esters rose and that of 14:0 + 16:1 and 20:4 fell. Concomitantly, in their mothers, the proportion of 20:4 increased but that of 16:0 and 18:0 decreased.

Animals↗

PubMed2001

Fissure sealing: optimization of sealant penetration and sealing properties.

PURPOSE: This in vitro study determined the penetration depth of a fissure sealant into an empty fissure system and into a conditioned enamel surface, using different sealing procedures. MATERIALS AND METHODS: 48 extracted, non-carious human molars were sealed with the unfilled sealant (Heliobond) using the enamel adhesive technique (35% phosphoric acid gel, 120 s etching time, bond application, light-curing for 60 s). The following factors were tested in comparison to the control group (1): influence of a precuring time lapse of 20 s after sealant application (2); ultrasound application with a plastic tip during the etching procedure (3); a wetting agent in an acid vehicle (4); enamel drying with acetone after the etching procedure (5); and finally, the combination of ultrasound during etching; a drying procedure with acetone; and a 20 s precuring time lapse (all applied to the same sample). The sealed teeth were sectioned and evaluated by conventional light microscopy to determine the penetration depth into the fissure, and by confocal laser microscopy to investigate the quality of the adhesion zone. RESULTS: Strict adherence to a specified penetration time, an intensified etching procedure with ultrasound, and the use of a drying procedure with acetone each showed a positive effect on the fissure penetration depth of the sealant and on the adhesion zone. The combination of these measures improved significantly the quality of the fissure sealing. Penetration depth increased to 92% of the fissure depth. From 95-100% of the total length of the analyzed adhesion zone shows excellent tags of sealant in the conditioned enamel surface. CLINICAL SIGNIFICANCE: Simple changes in the application technique of fissure sealants, such as ultrasonic treatment during etching procedure and drying the etched fissure system by acetone, improved the quality of the fissure sealing, which is a noninvasive preventive measure.

Acetone↗

PubMed1992

Antarctic seals carry antibodies against seal herpesvirus.

Weddell seals in the Antarctica had high neutralizing antibody titres to seal- and feline herpesvirus and none against phocine distemper virus. Crab-eater seals were free of antibodies. This suggests an evolutionary wide spread of seal herpesvirus.

Animals↗

PubMed1994

Characterization of cytopathogenicity of aquarium seal mycoplasmas and seal finger mycoplasmas by light and scanning electron microscopy.

Two recent mycoplasma isolates (one from an aquarium seal and one from a patient with the clinical entity known as seal finger) have been evaluated for cytopathogenicity in tracheal explant cultures. Examinations were performed in direct comparison to Mycoplasma phocidae, an isolate from an epidemic of seal pneumonia along the New England coast (USA) in 1979-1980. The study revealed similar inhibitory effects on ciliated tracheal epithelial cells and clumping of cilia by attached mycoplasmas; no exfoliation of respiratory epithelial cells was observed. In addition, cytopathic effects caused by the mycoplasmas were distinguished from effects of aging in non-infected explants under long-term in-vitro cultivation conditions. The general meaning of mycoplasmas in seals is discussed in detail in this paper.

Animals↗

PubMed1995

A new cardiac wall substitute made of Dacron fabric prosthesis sealed with autologous tissue fragments: comparative studies of neointima formation and bleeding resistant property against fibrinolysis phenomenon with those of a preclotted sealing graft.

A cardiac wall substitute made of a Dacron fabric prosthesis sealed with minced-autologous tissue fragments was developed. An animal study showed rapid neointima formation on the graft luminal surface and no bleeding problem under load test with tissue plasminogen activator (tPA) administration. To evaluate the efficacy of the sealing method, a special substitute that was sealed with tissue fragments in one half and preclotted with fresh blood in the other half was prepared. The grafts were implanted into the right ventricular outflow tract in 14 dogs. During a load test with administration of tPA intravenously, the preclotted area bled quite remarkably; however, the area sealed with tissue fragments did not bleed. Two weeks after implantation, red thrombus adhered on the preclotted area, while a white, glistening surface was noticed on the tissue fragments area. Light microscopical observation showed complete neointima formation in the tissue fragmented area but a thrombus layer in the preclotted area. These results indicated that the tissue fragmentation was a superior method compared with preclotting for creating a cardiac wall substitute.

Adipose Tissue↗

PubMed2001

A comparative evaluation of sealing ability of restorative materials used for coronal sealing after root canal therapy.

In the past few years the importance of coronal seal following root canal therapy has been emphasised. Adhesive restorative materials have been used, considering their good bond strength and their sealing ability. In this study, the sealing ability of resin modified glass ionomer has been compared with composite resin used with fifth generation bonding agent (in vitro), using methylene blue dye penetration method. Resin modified glass ionomer showed greater leakage than composite resin, although it was not statistically significant. Further studies are needed to asses the sealing efficacy in clinical situations.

Composite Resins↗

PubMed2003

Improper sealing caused by the Styrofoam integrity seals in leakproof plastic bottles lead to significant loss of ethanol in frozen evidentiary urine samples.

Evidentiary urine samples (n = 345) stored frozen at -20 degrees C in their original containers (leakproof 100 mL plastic bottles) upon retesting for ethanol resulted in concentrations that were significantly lower (average loss = approximately 30%) than those prior to their storage at -20 degrees C (p < or = 0.0001). The observed loss of ethanol was independent of the method of thawing or the concentration of ethanol in the samples, but was dependent on the sample volume in the container, i.e., the larger the volume of sample the larger the magnitude of ethanol loss. The loss of ethanol was determined to be due to improper sealing by a Styrofoam integrity seal attached to the mouth of the container. Accordingly, adopting leakproof plastic containers that do not contain Styrofoam integrity seals, but rather an outside and across the cap tape integrity seal for evidence collection and long-term storage, will prevent loss of ethanol due to evaporation.

Adult↗

PubMed1995

[Corneoscleral wound healing after self-sealing cataract surgery--3. Effect of postoperative intraocular pressure on wound sealing].

We investigated histologically the effect of postoperative intraocular pressure (IOP) on wound sealing after self-sealing cataract surgery in rabbits. A scleral pocket and internal corneal flap were made according to Ernest's method, and phacoemulsification was performed. Balanced salt solution was injected to self-seal the wound and to raise the IOP to 30 mmHg (high IOP group), to raise the IOP to 30 mmHg and then lower it to 15 mmHg (high-low IOP group), or to raise the IOP to only 15 mmHg (low IOP group). After various days, the eyes were analyzed by corneal topography and enucleated. The corneoscleral tissues were examined histologically. The wound adaptation was good in the high IOP group and the high-low IOP group on the external and internal sides on the first day after operation, but the wound adhesion was poor in the low IOP group even on the fourth day and became attached on the seventh day. We suggest that the difference of wound sealing caused by different postoperative IOPs might affect early postoperative astigmatism.

Animals↗

PubMed1998

Bacterial isolates from California sea lions (Zalophus californianus), harbor seals (Phoca vitulina), and northern elephant seals (Mirounga angustirostris) admitted to a rehabilitation center along the central California coast, 1994-1995.

In 2 yr of bacteriologic culturing of 297 California sea lions (Zalophus californianus), 154 harbor seals (Phoca vitulina), and 89 northern elephant seals (Mirounga angustirostris) stranded alive along the California coast, the most frequent isolates from inflammatory lesions in live animals were Escherichia coli, Streptococcus viridans, Listeria ivanovii, beta-hemolytic Streptococcus spp., and Enterococcus spp. This is the first report of L. ivanovii isolation from a marine mammal. The common isolates from lung and liver in animals dying during rehabilitation were E. coli, Salmonella spp., Klebsiella spp., Pseudomonas spp., Aeromonas spp., Proteus spp., and Staphylococcus aureus. The most common isolates from brain were Enterococcus spp., E. coli, Klebsiella spp., and Pseudomonas spp. Ocular lesions were seen most often in harbor seals and elephant seals, from which the isolates cultured included Pseudomonas spp., Enterococcus spp., Streptococcus viridans, E. coli, Staphylococcus aureus, Proteus spp., Morganella morganii, Moraxella spp., beta-hemolytic Streptococcus spp., and L. ivanovii. Nine different Salmonella serotypes were isolated from 49 animals; S. newport was the most common. These results should enable those working clinically with these species to make logical decisions in choosing initial antimicrobial therapy.

Abscess↗

PubMed1992

The serological response of the common seal (Phoca vitulina) and the grey seal (Halichoerus grypus) to phocine distemper virus as measured by a canine distemper virus neutralisation test.

The application of a canine distemper virus (CDV) neutralisation test revealed that antibody titres of up to 11,620 were present in the sera of common seals during the epizootic of phocine distemper in British waters. However, during the later stages of the epizootic and afterwards, a surprisingly high proportion of animals were still seronegative. Titres of from 90 to 183 were common in diseased animals and were probably indicative of partial immunosuppression. A few animals with proven phocine distemper had titres of less than 64, this being evidence of a more profound immunosuppression. Recovered animals tended to have moderate to high titres and in some cases these persisted for at least 6.5 months. By contrast, the administration of an inactivated CDV vaccine produced antibody which declined rapidly to very low levels within the same period. Infection also occurred in grey seals in 1988 but without severe mortality. Antibody titres in this species nearly always lay in the range 128-734 and persisted at or around this level for at least 12 months. In both common and grey seals, antibody was transferred by suckling from mother to pup but absorption by the pup seemed to take place more slowly than in domestic mammals.

Animals↗

PubMedDate not supplied

Identification and partial characterization of common seal (Phoca vitulina) and grey seal (Haliochoerus grypus) interleukin-6-like activities.

Interleukin-6 (IL-6) is a pleiotropic molecule with many important immune modulatory actions. We have investigated the production of biological activity of this cytokine in two species of European seal. IL-6-like activity was detected in supernatants from cultured peripheral blood leucocytes. This IL-6-like activity had an apparent molecular weight of 17-26 kDa, similar to that of human IL-6. IL-6-like activity was also detected in plasma taken from seals with symptoms of systemic infection, but not from apparently healthy seals. Inhibition of this plasma and leucocyte derived activity was accomplished with both rabbit and goat antisera raised against recombinant human IL-6. Further investigation using polymyxin-B showed that this activity was not due to residue LPS present in the supernatants or infected plasmas.

Animals↗