Seal Lung Research Articles

Brucella pinnipedialis in lungworms Parafilaroides sp. and Pacific harbor seals Phoca vitulina richardsi: proposed pathogenesis.

Brucella spp. were first isolated from marine mammals in 1994 and since have been described in numerous pinniped and cetacean species with nearly global distribution. Microscopic, electron microscopic, or culture results have shown lungworms in harbor seals to be infected with brucellae, suggesting that the lungworms may serve a role in this infection. In this study, we reviewed archived and more recent case material from 5 Pacific harbor seals from Washington State (USA) with evidence of B. pinnipedialis infection in the lungworm Parafilaroides sp. Twenty-two sections of lung containing approximately 220 Parafilaroides sp., stained with an immunohistochemical technique using antibody to B. abortus, showed approximately 80 (36%) infected nematodes. A few brucellae were also present in lung parenchyma in proximity to nematodes. Infection was present in the first- and fourth-stage larvae in the seal lung and intestines, as well as in the male and female reproductive organs of adult nematodes. Infected sperm deposits in the nematode uterus were suggestive of venereal transmission between lungworms. Massive infection of some degenerate adult lungworms and evidence of degeneration of some developing larvae in utero were observed. Based on these observations, we suggest that Parafilaroides sp., rather than the Pacific harbor seal Phoca vitulina richardsi, is the preferred host of B. pinnipedialis infection.

Collapsing seal lungs protected by amazing anti-inflammatory blood serum

Seal lungs can take a terrible pounding when one of the mammals leaves the surface. Collapsing during deep descents to protect the animal from the bends, the delicate tissues must incur damage as they are crushed, and endure blood and oxygen flooding back when the animals return to the surface. In addition, the fragile tissues could suffer inflammation, which is usually triggered to heal injury. Yet Allyson Hindle from Harvard Medical School, USA, and colleagues from various institutions across the USA say, ‘There is no evidence that diving damages pulmonary function in these species’. Wondering how elephant and Weddell seals protect their lungs from the potentially damaging inflammatory response that should be triggered by diving injuries, the team tested whether blood samples from the two species offered any protection from the effects of inflammation triggered by a bacterial toxin, lipopolysaccharide.Impressively, the toxin barely triggered any inflammatory response in the seal blood, in contrast to human blood samples, which experienced inflammation that was 50 to 500 times greater. And when the team added seal blood extract to cells from the seals’ immune systems, the extract quenched the inflammatory response and was also able to reduce inflammation in mouse immune cells. ‘These data suggest that seal serum possesses anti-inflammatory properties, which may protect deep divers from naturally occurring inflammatory challenges such as dive-induced hypoxia–reoxygenation and lung collapse’, says the team, which would like to identify the protective compounds in the hope of being able to use them to extend the survival of organs used in life-saving transplant surgery.

COMPREHENSIVE DIAGNOSIS OF COMMUNITY-ACQUIRED PNEUMONIA METHOD OF FONOPNEUMOGRAHIA QUIET BREATHING

Background. Rate potentialities of phonopneumographia quiet breathing to diagnose the source of inflammation in patients with community-acquired pneumonia. Materials and methods. The study included 36 healthy men and 36 those with community-acquired pneumonia who underwent phonopneumographia quiet breathing. Result. It was found that the maximum specificity for the healthy group was 80,5%, the maximum sensitivity of detection of the source of inflammation – 83,3%. Consequently, the sensitivity phonopneumographia quiet breathing is much more sensitive than the subjective auscultation, which is 50 %. Conclusion. Acoustic change in the outbreak of pneumonia in line with the concept of pathomorphology inflammation in the lungs areas acoustic pattern (syndrome seal lung tissue) that characterizes the inflammatory focus pneumonia. Identified types of acoustic patterns and their thresholds for patients.

Metagenomic identification of a novel anellovirus in Pacific harbor seal (Phoca vitulina richardsii) lung samples and its detection in samples from multiple years

To investigate viral pathogens potentially involved in a mortality event of 21 Pacific harbor seals (Phoca vitulina richardsii) in California in 2000, viral metagenomics was performed directly on lung samples from five individuals. Metagenomics revealed a novel seal anellovirus (SealAV), which clusters phylogenetically with anelloviruses from California sea lions and domestic cats. Using specific PCR, SealAV was identified in lung tissue from two of five animals involved in the 2000 mortality event, as well as one of 20 harbor seal samples examined post-mortem in 2008. The identification of SealAV in multiple years demonstrates that this virus is persistent in the harbor seal population. SealAV is the second anellovirus reported in the lungs of pinnipeds, suggesting that anellovirus infections may be common amongst marine mammals and that more research is needed to understand the roles of these viruses in marine mammal health and disease.

Life at the Frontier

Life at the Frontier

Glutathione protection against dive-associated ischemia/reperfusion in ringed seal tissues

Ischemia/reperfusion is a potentially hazardous condition that increases reactive oxygen species (ROS) production and oxidative damage. Seals of the phocid family experience repetitive episodes of ischemia/reperfusion during and after a dive as a consequence of preferential distribution of blood flow to the central nervous system and reduction or elimination of perfusion in most vascular beds. Previous studies showed that ROS production is higher in ringed seal than in domestic pig tissues as a direct consequence of the ischemia/reperfusion associated with the diving response; however, oxidative damage is not related to this high ROS production. Apparently, antioxidant enzyme activities participate in the antioxidant protection in ringed seal tissues. In the present study we addressed the potential antioxidant protection of the glutathione system against dive-induced ischemia/reperfusion in ringed seal tissues. Total glutathione (GSH-Eq = GSH + 2GSSG), glutathione (GSH) and glutathione disulfide (GSSG), the ratio GSSG:GSH-Eq, the activities of the enzymes glutathione disulfide reductase (GR) and glucose-6-phosphate dehydrogenase (G6PDH), as well as lipid peroxidation (TBARS) and carbonyl proteins, were measured in ringed seal and domestic pig heart, kidney, liver, lung and muscle samples. In heart, kidney, lung and muscle GSH-Eq and GSH content was higher in seal than in pig ( p < 0.05). GSSG content was higher in seal than in pig heart kidney, liver and muscle ( p < 0.05). GR and G6PDH activities were higher in all seal than in pig tissues ( p < 0.05). GSSG:GSH-Eq ratio was higher in pig than in seal heart, and lung ( p < 0.05). TBARS content was higher in pig than in seal lung ( p < 0.05). Higher content of carbonyl proteins was present in pig than in seal heart, kidney, liver and muscle ( p < 0.05). These results suggest that the glutathione levels and the activity of enzymes involved in its recycling are efficient mechanisms that ameliorate protein and lipid oxidative damage and protect ringed seal tissues against dive-induced ischemia/reperfusion.

Microscopic Anatomy of the Ringed Seal (Phoca hispida) Lower Respiratory Tract

The microscopic anatomy of the ringed seal lung exhibits unique features and many features similar to those described in other seal species. Unique features include: Trachealis muscle predominately oriented longitudinally; Large veins within the tracheal wall supported by elastic fibers; Goblet cells and pseudostratified epithelium lining the duct system of bronchial glands of the segmental bronchi; Lamina propria of the segmental bronchus heavily invested with elastic fibers clustered into dense longitudinal bundles; and Capillaries and venules covered with squamous epithelium protruding into bronchiolar lumina. Common features include: Cartilage support of the bronchial tree extending distally into respiratory bronchioles; Smooth muscle enhancements in the distal airways producing sphincter like formations; and Lungs extensively supported with interstitial tissue, which divide lungs into lobules.

Antioxidant enzymes in ringed seal tissues: Potential protection against dive-associated ischemia/reperfusion

Diving seals experience heart rate reduction and preferential distribution of the oxygenated blood flow to the heart and brain, widespread peripheral vasoconstriction, and selective ischemia in the most hypoxia-tolerant tissues. The first breath after the dive restores the oxygenated blood flow to all tissues and raises the potential for the production of reactive oxygen species (ROS). We hypothesized that in order to counteract the damaging effects of ROS and to tolerate repetitive cycles of ischemia/reperfusion associated with diving, ringed seal (Phoca hispida) tissues have elevated activities of antioxidant enzymes. Activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione-S-transferase (GST) were measured by spectrophotometric techniques in heart, kidney, liver, lung, and muscle extracts of ringed seals and domestic pigs (Sus scrofa). The results suggest that in ringed seal heart SOD, GPx and GST activities are an efficient protective mechanism for counteracting ROS production and its deleterious effects. Apparently CAT activity in seal liver and GPx activity in seal muscle participate in the removal of hydroperoxides, while seal lung appears to be protected from oxidative damage by SOD and GPx activities.

Molecular cloning and expression of leptin in gray and harbor seal blubber, bone marrow, and lung and its potential role in marine mammal respiratory physiology

Leptin is a multifunctional hormone, produced predominantly in adipocytes. It regulates energy balance through its impact on appetite and fat metabolism, and its concentration indicates the size of body fat reserves. Leptin also plays a vital role in stretch-induced surfactant production during alveolar development in the fetus. The structure, expression pattern, and role of leptin have not previously been explored in marine mammals. Phocid seals undergo cyclical changes in body composition as a result of prolonged fasting and intensive foraging bouts and experience rapid, dramatic, and repeated changes in lung volume during diving. Here, we report the tissue-specific expression pattern of leptin in these animals. This is the first demonstration of leptin expression in the lung tissue of a mature mammal, in addition to its expression in the blubber and bone marrow, in common with other animals. We propose a role for leptin in seal pulmonary surfactant production, in addition to its likely role in long-term energy balance. We identify substitutions in the phocine leptin sequence in regions normally highly conserved between widely distinct vertebrate groups, and, using a purified seal leptin antiserum, we confirm the presence of the leptin protein in gray seal lung and serum fractions. Finally, we report the substantial inadequacies of using heterologous antibodies to measure leptin in unextracted gray seal serum.

Hypoxia-Inducible Factor in Ringed Seal (Phoca hispida) Tissues

Tissue hypoxia and ischemia–reperfusion pose a dangerous situation for oxidative stress. However, diving mammals and birds show pronounced resistance to oxidative injury under such conditions, which are a consequence of selective vasoconstriction during a dive. As the function of Hypoxia-Inducible Factor-1α (HIF-1α) in protection against and adaptation to hypoxia has been recognized in terrestrial animals, we have investigated the genomics and expression of this protein in ringed seal (Phoca hispida) in order to determine if it may play a protective role in this diving mammal. PCR studies using primers based on sequences from mouse HIF-1α exons 3, 4, 5, 6, 9, 10, 11, 12 and 15 showed that DNA from seal lung generated PCR products similar to those from mouse DNA. These studies have established that a putative HIF-1α gene exists in the seal genome that appears to have a similar but not identical sequence to the mouse gene. Seal lung and skeletal muscle tissues showed the highest relative levels of HIF-1α protein expression, with heart muscle showing significantly lower levels, and levels of HIF-1β protein expression paralleled this situation. Analysis of oxidized cellular protein levels indicated that seal lung and heart muscle had the lowest levels of oxidized proteins. Thus, as seal lung tissue had the highest level of HIF-1α protein expression and the second lowest level of protein oxidation, this suggests that HIF-1α expression may have an important protective effect in this tissue in diving mammals. Our results support the hypothesis that HIF-1α expression is dependent on both tissue-specific energy requirements and adequate metabolic supply-to-demand ratio. Combined, the evidence available suggests that diving mammals have an overall anticipatory response to avoid the ill effects of dive-associated ischemia–reperfusion which may involve the HIF-1 system.

Control of pulmonary surfactant secretion in adult California sea lions

Marine mammals have a spectacular suite of respiratory adaptations to deal with the extreme pressures associated with deep diving. In particular, maintaining a functional pulmonary surfactant system at depth is critical for marine mammals to ensure that inspiration is possible upon re-emergence. Pulmonary surfactant is secreted from alveolar type II (ATII) cells and is crucial for normal lung function. It is not known whether ATII cells have the ability to continue to secrete pulmonary surfactant under pressure, or how secretion is maintained and controlled. We show here that surfactant secretion in California sea lions ( Zalophus californianus) was increased after high pressures (25 and 50 atm) of short duration (30 min), but was unaffected by high pressures of long duration (2 h). This is in contrast to a similar sized terrestrial mammal (sheep), where surfactant secretion was increased after high pressures of both long and short duration. Z. californianus and terrestrial mammals also show similar responses to stimulatory hormones and autonomic neurotransmitters. It therefore seems that an increase in the quantity of surfactant in seal lungs after diving is most likely caused by mechanostimulation induced by pressure and volume changes, and that seals are adapted to maintain constant levels of surfactant under long periods of high pressure.

Lobe-sparing resection of multiple pulmonary metastases with a new 1318-nm Nd:YAG laser—first 100 patients

Background. A new 1318-nm Nd:YAG laser has been developed to utilize the second wavelength (1318 nm; 40 watt) to more precisely cut, coagulate, and seal lung tissue adjacent to pulmonary nodules. This laser allows a precise intraparenchymal nodulectomy with a 5-mm rim of tissue destruction and subsequent lung parenchymal reapproximation to avoid lobar distortion. Resection of multiple, bilateral, and recurrent tumors in the lung is facilitated by this laser technique. Methods. In 100 consecutive patients (53 men, mean age 60 years; 47 women, mean age 61 years) with various primaries (most commonly renal and colorectal), 155 laser resections were performed via anterolateral thoracotomy (staged 3 to 4 weeks, if bilateral) using a new 1318-nm Nd:YAG laser. All palpable and visible masses were removed with 2 to 3-mm visible tumor margins (plus a 5-mm rim of residual lung necrosis secondary to laser energy dispersal) if the tumor or residual lung ratio was judged favorable. No stapling devices or bioadhesives were used. Results. Six hundred thirty-two metastases (6.3 per patient, range 1 to 124) were resected. Despite 41% centrally located metastases, tumor resections were possible in 95% of patients with only a 5% lobectomy rate. Of the 100 patients, 67 were considered “curative” with complete metastasectomy by inspection and palpation, and 23 were judged incomplete from too extensive tumor or residual lung, miliary lung spread, or pleural studding. There were no associated mortalities and two complications, including bleeding (1) and a prolonged airleak (1), both treated conservatively. Follow-up was complete in all patients for a median of 26.5 months with clinic visits and chest computed tomographic scan every 3 to 6 months. Nine recurrences were detected and underwent reoperation. Overall survival in the completely resected “curative” group was 85% at 1 year, 71% at 2 years, 69% at 3 years, 57% at 4 years, and 32% at 5 years; in the completely resected “palliative” group, they were 70% at 1 year, 36% at 2 years, 12% at 3 years, and 0 at 4 years; in the incomplete group, they were 56% at 1 year, 30% at 2 years, and 0 at 3 years. Conclusions. The new 1318-nm Nd:YAG laser is parenchyma-sparing, improves complete resection rates, and potentially improves survival with fewer required lobectomies.

Seal lungs collapse during free diving: evidence from arterial nitrogen tensions.

Arterial blood nitrogen tensions of free-diving Weddell seals (Leptonychotes weddelli) were measured by attaching a microprocessor-controlled blood pump and drawing samples at depth to determine how these marine mammals dive to great depths and ascend rapidly without developing decompression sickness. Forty-seven samples of arterial blood were obtained from four Weddell seals during free dives lasting up to 23 minutes to depths of 230 meters beneath the sea ice of McMurdo Sound, Antarctica. Peak arterial blood nitrogen tensions of between 2000 and 2500 millimeters of mercury were recorded at depths of 40 to 80 meters during descent, indicating that the seal's lung collapses by 25 to 50 meters. Then arterial blood nitrogen tensions slowly decreased to about 1500 millimeters of mercury at the surface. In a single dive, alveolar collapse and redistribution of blood nitrogen allow the seal to avoid nitrogen narcosis and decompression sickness.

Histological development of the terminal airways in pinniped and sea otter lungs

A histological study by light microscopy on the development of the terminal airways in fetal lungs of the harbor seal (Phoca vitulina), northern sea lion (Eumetopias jubatus), and sea otter (Enhydra lutris) showed the development of muscle and cartilaginous rings to occur late in gestation. At term they were still much less developed than in the terminal airways seen in adults. The most extensive reinforcement with cartilage of the terminal airways was observed in the sea lion lungs and the least in the seal lungs. The fetal lung development was contrasted with that of the porpoise. We conclude that unlike the porpoise, much further development of the terminal airways in pinnipeds and sea otters occurs during the neonatal stage when the animal is nondiving in a "terrestrial" environment.

The structure and function of the small airways in pinniped and sea otter lungs

We have looked at the structure of the small airways from the lungs of 58 marine mammals. Six were from sea otters, the others were from 14 of the 21 pinniped genera. In comparison with the terminal airways of terrestrial mammals all showed reinforcement by muscle and/or cartilage. The small airways of phocid seal lungs were reinforced by a moderately slender tube of oblique muscle. Those of otariid seals were strengthened by very much thicker pieces of cartilage. The airways of sea-otter and walrus lungs were of an intermediate pattern. Both types of reinforcement seem to appear late in foetal life rather than by arrest of development. Calculations suggest the reinforcement in otariid lungs may be excessive for limiting nitrogen absorption during deep dives and behavioural observations indicate that strengthened airways may also be required for rapid ventilation at the surface between dives.