NEJM Evidence - A New Journal in the NEJM Group Family

NEJM Evidence - A New Journal in the NEJM Group Family In January 2022, the NEJM Group will be publishing a new journal, NEJM Evidence. This monthly, peer-reviewed, online-only, general medical journal will publish original research, along the full spectrum of clinical investigation, that takes ideas and turns them into reality.

Report of the workshop Evaluating the nature of midwater mining plumes and their potential effects on midwater ecosystems

The International Seabed Authority (ISA) is developing regulations to control the future exploitation of deep-sea mineral resources including sulphide deposits near hydrothermal vents, polymetallic nodules on the abyssal seafloor, and cobalt crusts on seamounts. Under the UN Convention on the Law of the Sea the ISA is required to adopt are taking measures to ensure the effective protection of the marine environment from harmful effects arising from mining-related activities. Contractors are required to generate environmental baselines and assess the potential environmental consequences of deep seafloor mining. Understandably, nearly all environmental research has focused on the seafloor where the most direct mining effects will occur. However, sediment plumes and other impacts (e.g., noise) from seafloor mining are likely to be extensive in the water column. Sediment plumes created on the seafloor will affect the benthic boundary layer which extends 10s to 100s of meters above the seafloor. Separation or dewatering of ore from sediment and seawater aboard ships will require discharge of a dewatering plume at some depth in the water column.

It is important to consider the potential impacts of mining on the ocean’s midwaters (depths from ~200 m to the seafloor) because they provide vital ecosystem services and harbor substantial biodiversity. The better known epipelagic or sunlit surface ocean provisions the rest of the water column through primary production and export flux (This was not the focus at this workshop as the subject was considered too large and surface discharges are unlikely). It is also home to a diverse community of organisms including commercially important fishes such as tunas, billfish, and cephalopods that contribute to the economies of many countries. The mesopelagic or twilight zone (200-1000 m) is dimly lit and home to very diverse and abundant communities of organisms. Mesopelagic plankton and small nekton form the forage base for many deep-diving marine mammals and commercially harvested epipelagic species. Furthermore, detritus from the epipelagic zone falls through the mesopelagic where it is either recycled, providing the vital process of nutrient regeneration, or sinks to greater depths sequestering carbon from short-term atmospheric cycles. The waters below the mesopelagic down to the seafloor (both the bathypelagic and abyssopelagic) are very poorly characterized but are likely large reservoirs of novel biodiversity and link the surface and benthic ecosystems.

Great strides have been made in understanding the biodiversity and ecosystem function of the ocean’s midwaters, but large regions, including those containing many exploration license areas and the greater depths where mining plumes will occur, remain very poorly studied. It is clear that pelagic communities are distinct from those on the seafloor and in the benthic boundary layer. They are often sampled with different instrumentation. The fauna have relatively large biogeographic ranges and they are more apt to mix freely across stakeholder boundaries, reference areas and other spatial management zones. Pelagic organisms live in a three-dimensional habitat and their food webs and populations are vertically connected by daily or lifetime migrations and the sinking flux of detritus from the epipelagic. The fauna do not normally encounter hard surfaces, making them fragile, and difficult to capture and maintain for sensitivity or toxicity studies. Despite some existing general knowledge, ecological baselines for midwater communities and ecosystems that likely will be impacted by mining have not been documented. There is an urgent need to conduct more research and evaluate the midwater biota (microbes to fishes) in regions where mining is likely to occur.

Deep-sea mining activities may affect midwater organisms in a number of ways, but it is still unclear at what scale perturbations may occur. The sediment plumes both from collectors on the seafloor and from midwater discharge will have a host of negative consequences. They may cause respiratory distress from clogged gills or respiratory surfaces. Suspension feeders, such as copepods, polychaetes, salps, and appendicularians, that filter small particles from the water and form an important basal group of the food web, may suffer from dilution of their food by inorganic sediments and/or clogging of their fragile mucous filter nets. Small particles may settle on gelatinous plankton causing buoyancy issues. Metals, including toxic elements that will enter the food web, will be released from pore waters and crushed ore materials. Sediment plumes will also absorb light and change backscatter properties, reducing visual communication and bioluminescent signaling that are very important for prey capture and reproduction in midwater animals. Noise from mining activities may alter the behaviors of marine mammals and other animals. Small particles have high surface area to volume ratios, high pelagic persistence and dispersal and as a result greater potential to result in pelagic impacts. All of these potential effects will result in mortality, migration (both horizontal and vertical), decreased fitness, and shifts in community composition. Depending on the scale and duration of these effects, there could be reduction in provisioning to commercial fish species, delivery of toxic metals to pelagic food webs and hence human seafood supply, and alterations to carbon transport and nutrient regeneration services.

After four days of presentations and discussions, the workshop participants came to several conclusions and synthesized recommendations.

1. Assuming no discharge in the epipelagic zone, it is essential to minimize mining effects in the mesopelagic zone because of links to our human seafood supply as well as other ecosystem services provided by the mesopelagic fauna. This minimization could be accomplished by delivering dewatering discharge well below the mesopelagic/bathypelagic transition (below ~1000 m depth).

2. Research should be promoted by the ISA and other bodies to study the bathypelagic and abyssopelagic zones (from ~1000 m depths to just above the seafloor). It is likely that both collector plumes and dewatering plumes will be created in the bathypelagic, yet this zone is extremely understudied and contains major unknowns for evaluating mining impacts.

3. Management objectives, regulations and management actions need to prevent the creation of a persistent regional scale “haze” (enhanced suspended particle concentrations) in pelagic midwaters. Such a haze would very likely cause chronic harm to deep midwater ecosystem biodiversity, structure and function.

4. Effort is needed to craft suitable standards, thresholds, and indicators of harmful environmental effects that are appropriate to pelagic ecosystems. In particular, suspension feeders are very important ecologically and are likely to be very sensitive to sediment plumes. They are a high priority for study.

5. Particularly noisy mining activities such as ore grinding at seamounts and hydrothermal vents is of concern to deep diving marine mammals and other species. One way to minimize sound impacts would be to minimize activities in the sound-fixing-and-ranging (SOFAR) channel (typically at depths of ~1000 m) which transmits sounds over very long distances.

6. A Lagrangian (drifting) perspective is needed in monitoring and management because the pelagic ecosystem is not a fixed habitat and mining effects are likely to cross spatial management boundaries. For example, potential broad-scale impacts to pelagic ecosystems should be considered in the deliberations over preservation reference zones, the choice of stations for environmental baseline and monitoring studies and other area-based management and conservation measures.

7. Much more modeling and empirical study of realistic mining sediment plumes is needed. Plume models will help evaluate the spatial and temporal extent of pelagic (as well as benthic) ecosystem effects and help to assess risks from different technologies and mining scenarios. Plume modeling should include realistic mining scenarios (including duration) and assess the spatial-temporal scales over which particle concentrations exceed baseline levels and interfere with light transmission to elucidate potential stresses on communities and ecosystem services. Models should include both near and far field-phases, incorporating realistic near field parameters of plume generation, flocculation, particle sinking, and other processes. It is important to note that some inputs to these models such as physical oceanographic parameters are lacking and should be acquired in the near-term. Plume models need to be complemented by studies to understand effects on biological components by certain particle sizes and concentrations.

Deep-sea octopus (Graneledone boreopacifica) conducts the longest-known egg-brooding period of any animal

Octopuses typically have a single reproductive period and then they die (semelparity). Once a clutch of fertilized eggs has been produced, the female protects and tends them until they hatch. In most shallow-water species this period of parental care can last from 1 to 3 months, but very little is known about the brooding of deep-living species. In the cold, dark waters of the deep ocean, metabolic processes are often slower than their counterparts at shallower depths. Extrapolations from data on shallow-water octopus species suggest that lower temperatures would prolong embryonic development periods. Likewise, laboratory studies have linked lower temperatures to longer brooding periods in cephalopods, but direct evidence has not been available. We found an opportunity to directly measure the brooding period of the deep-sea octopus Graneledone boreopacifica, in its natural habitat. At 53 months, it is by far the longest egg-brooding period ever reported for any animal species. These surprising results emphasize the selective value of prolonged embryonic development in order to produce competitive hatchlings. They also extend the known boundaries of physiological adaptations for life in the deep sea.

Prioritised research agenda for prevention and control of chronic respiratory diseases

The 2008-2013 World Health Organization (WHO) action plan on noncommunicable diseases (NCDs) includes chronic respiratory diseases as one of its four priorities. Major chronic respiratory diseases (CRDs) include asthma and rhinitis, chronic obstructive pulmonary disease, occupational lung diseases, sleep-disordered breathing, pulmonary hypertension, bronchiectiasis and pulmonary interstitial diseases. A billion people suffer from chronic respiratory diseases, the majority being in developing countries. CRDs have major adverse effects on the life and disability of patients. Effective intervention plans can prevent and control CRDs, thus reducing morbidity and mortality. A prioritised research agenda should encapsulate all of these considerations in the frame of the global fight against NCDs. This requires both CRD-targeted interventions and transverse NCD programmes which include CRDs, with emphasis on health promotion and disease prevention.

Corticosteroid pharmacogenetics: association of sequence variants in CRHR1 with improved lung function in asthmatics treated with inhaled corticosteroids

Corticosteroids mediate a variety of immunological actions and are commonly utilized in the treatment of a wide range of diseases. Unfortunately, therapy with this class of medications is associated with a large proportion of non-responders and significant side effects. Inhaled corticosteroids are the most commonly used asthma controller therapy. However, asthmatic response to corticosteroids also varies widely between individuals. We investigated the genetic contribution to the variation in response to inhaled corticosteroid therapy in asthma. The association of longitudinal change in lung function and single nucleotide polymorphisms from candidate genes crucial to the biologic actions of corticosteroids were evaluated in three independent asthmatic clinical trial populations utilizing inhaled corticosteroids as the primary therapy in at least one treatment arm. Variation in one gene, corticotropin-releasing hormone receptor 1 (CRHR1) was consistently associated with enhanced response to therapy in each of our three populations. Individuals homozygous for the variants of interest manifested a doubling to quadrupling of the lung function response to corticosteroids compared with lack of the variants (P-values ranging from 0.006 to 0.025 for our three asthmatic populations). As the primary receptor mediating the release of adrenocorticotropic hormone, which regulates endogenous cortisol levels, CRHR1 plays a pivotal, pleiotropic role in steroid biology. These data indicate that genetic variants in CRHR1 have pharmacogenetic effects influencing asthmatic response to corticosteroids, provide a rationale for predicting therapeutic response in asthma and other corticosteroid-treated diseases, and suggests this gene pathway as a potential novel therapeutic target.

International Union of Pharmacology XLIV. Nomenclature for the Oxoeicosanoid Receptor

Oxoeicosanoids are a family of biologically active arachidonic acid derivatives that have been intimately linked with cellular migration. These metabolites are not only potent chemotaxins but also elicit oxygen radical production as well as induce secretory events in different cells. The most potent native ligand reported is 5-oxo-6,8,11,14-eicosatetraenoic acid (5-oxo-ETE), and the cell membrane receptor activated has now been cloned. This receptor is distinct from those receptors activated by either the prostaglandins or the leukotrienes. The purpose of this review is to briefly summarize the molecular evidence and highlight the significance of this receptor. In addition, an official nomenclature for this oxoeicosanoid receptor is proposed.

International Union of Pharmacology XXXVII. Nomenclature for leukotriene and lipoxin receptors

The leukotrienes and lipoxins are biologically active metabolites derived from arachidonic acid. Their diverse and potent actions are associated with specific receptors. Recent molecular techniques have established the nucleotide and amino acid sequences and confirmed the evidence that suggested the existence of different G-protein-coupled receptors for these lipid mediators. The nomenclature for these receptors has now been established for the leukotrienes. BLT receptors are activated by leukotriene B(4) and related hydroxyacids and this class of receptors can be subdivided into BLT(1) and BLT(2). The cysteinyl-leukotrienes (LT) activate another group called CysLT receptors, which are referred to as CysLT(1) and CysLT(2). A provisional nomenclature for the lipoxin receptor has also been proposed. LXA(4) and LXB(4) activate the ALX receptor and LXB(4) may also activate another putative receptor. However this latter receptor has not been cloned. The aim of this review is to provide the molecular evidence as well as the properties and significance of the leukotriene and lipoxin receptors, which has lead to the present nomenclature.

Urinary leukotriene (LT) E(4) in adolescents with dysmenorrhea: a pilot study

In the present study we measured levels of urinary leukotriene (LT) E(4) as an index of LT production during the menstrual cycle in adolescents. Mean urinary LTE(4) levels in girls with dysmenorrhea was approximately threefold higher than normal laboratory values on Day 1 of the menstrual period and approximately twofold higher than normal laboratory values on Day 5 of the menstrual period. Compared with urinary LTE(4) levels in girls with eumenorrhea, urinary LTE(4) levels in girls with dysmenorrhea were higher on Day 1 [361 +/- 123 pg/mg creatinine vs. 122 +/- 37 pg/mg creatinine, p =.1; not significant (NS)] and on Day 5 (202 +/- 26 pg/mg creatinine vs. 117 +/- 26 pg/mg creatinine, p <.05) of the menstrual period, as well as on Day 10 (159 +/- 33 pg/mg creatinine vs. 88 +/- 21 pg/mg creatinine, p =.1; NS) of the menstrual cycle. Increased urinary excretion of leukotrienes, inflammatory mediators known to cause potent vasoconstriction and uterine contractions, in girls with dysmenorrhea in this pilot study, suggests that these mediators may be involved in generating dysmenorrhea symptoms in adolescents.

Recurrent panniculitis in a man with asthma receiving treatment with leukotriene-modifying agents

Leukotriene-modifying drugs are novel agents introduced recently to treat asthma. Both 5-lipoxygenase inhibitors, such as zileuton, and leukotriene receptor antagonists, such as zafirlukast and montelukast, have proved effective in the treatment of asthma. To our knowledge, there have been no detailed reports regarding dermatologic manifestations of this class of drugs. This article describes an unusual case of erythema nodosum in a 46-year-old asthmatic man who received 2 different leukotriene modifiers.

Clinical pharmacology of leukotriene receptor antagonists and 5-lipoxygenase inhibitors

Blinded, randomized, and placebo-controlled clinical trials have established that cysteinyl leukotriene (cysLT) receptor antagonists and 5-lipoxygenase (5-LO) inhibitors are safe and effective asthma treatments. Trials of 13- to 26-wks' duration demonstrate that both the cysLT1 receptor antagonist, zafirlukast, and the 5-LO inhibitor, zileuton, improve pulmonary function and decrease daytime and nocturnal symptoms. Concomitant rescue beta-agonist inhaler use and the need for corticosteroid rescue are also reduced. Preliminary studies suggest that antileukotriene agents may also reduce indices of airway inflammation, including inflammatory cell counts and airway hyperresponsiveness. Both cysLT1 antagonists and 5-LO inhibitors offer a new approach to asthma management.

Clinical studies with agents active on the 5-lipoxygenase pathway

Leukotrienes may be considered asthmatic mediators. Compounds inhibiting their production and activity show promise in the treatment of asthma. Further clinical studies will determine the clinical usefulness of such agents.

Nitric oxide synthase in human and rat lung: immunocytochemical and histochemical localization

Nitric oxide synthase (NOS) produces nitric oxide, a mediator of potential importance in numerous physiologic and inflammatory processes in the lung. We localized constitutive NOS (c-NOS) and inducible NOS (i-NOS) within lung tissue by immunoperoxidase labeling with specific antibodies or by histochemical demonstration of the characteristic NADPH diaphorase activity of NOS. We analyzed human airway (n = 4) or parenchyma (n = 10) specimens obtained from uninvolved areas of surgical tumor resections. We also studied human fetal lung samples (n = 6) and normal or inflamed (16 h after intratracheal LPS instillation) rat lung tissue. Immunostaining with anti-c-NOS identified c-NOS antigen in rat lung nerves, endothelium, and airway epithelium. Normal or inflamed rat macrophages were not stained. Human nerve elements and large-vessel endothelium showed immunostaining with the anti-c-NOS, but no labeling of the airway or alveolar epithelium was seen. Immunostaining with anti-i-NOS showed strong labeling of rat macrophages after LPS treatment, in vivo or in vitro, while normals were negative. Human alveolar macrophages were occasionally positive for i-NOS, especially in areas of chronic inflammation, which also showed focal immunolabeling of endothelium. Uniform labeling of epithelium in large, cartilaginous airways was found with anti-i-NOS in both human bronchi and normal rat trachea samples, suggesting a constitutive role for a NOS that shares epitope(s) with or is highly homologous to the inducible, macrophage type of NOS. Histochemical staining for NADPH diaphorase activity was consistent with immunolocalization of NOS antigens.(ABSTRACT TRUNCATED AT 250 WORDS)

Human alveolar macrophages have 15-lipoxygenase and generate 15(S)-hydroxy-5,8,11-cis-13-trans-eicosatetraenoic acid and lipoxins

Eicosanoids derived from lipoxygenase (LO)-catalyzed reactions play important roles in pulmonary inflammation. Here, we examined formation of LO-derived products by human alveolar macrophages (HAM). HAM converted [1-14C]-arachidonic acid to a product carrying 14C-radiolabel that was identified as 15(S)-hydroxy-5,8,11-cis-13-trans-eicosatetraenoic acid (15-HETE) by physical methods. 15-LO mRNA was demonstrated in HAM by reverse transcription-polymerase chain reaction. Incubation of HAM for 3 d with interleukin 4(IL-4) before exposure to [1-14C]arachidonic acid led to both increased mRNA for 15-LO and a 4-fold increase in 15-HETE formation. In contrast, 5(S)-hydroxy-6-trans-8,11,14-cis-eicosatetraenoic acid generation was not significantly altered by prior exposure to IL-4. Additionally, lipoxins (LXA4 and LXB4) were detected from endogenous substrate, albeit in lower levels than leukotriene B4 (LTB4), in electrochemical detection/high performance liquid chromatography profiles from HAM incubated in the presence and absence of the chemotactic peptide (FMLP) or the calcium ionophore (A23187). Exposure of HAM to leukotriene A4 (LTA4) resulted in a 2-fold increase in LXA4 and 10-fold increase in LXB4. These results demonstrate the presence of 15-LO mRNA and enzyme activity in HAM and the production of LXA4 and LXB4 by these cells. Along with 5-LO-derived products, the biosynthesis of 15-LO-derived eicosanoids by HAM may also be relevant in modulating inflammatory responses in the lung.

The relaxant properties in guinea pig airways of S-nitrosothiols

Several cellular constituents of the lung have the capacity to synthesize a factor capable of relaxing smooth muscle which has the physicochemical properties of nitric oxide (NO). In other systems, it has been shown that NO may be stabilized in the plasma and cellular milieu by reduced thiol in the form of an S-nitrosothiol (RS-NO). These compounds have half-lives that are significantly greater than that of NO, and also retain the vasorelaxant activity of NO, which is mediated by activating guanylate cyclase and raising cyclic GMP levels. The effects of RS-NO and their potential mechanism of action on airways, however, have not been previously investigated. In this study, we have examined the smooth muscle relaxant properties of several biological and synthetic RS-NO on guinea pig trachea. Our data reveal that RS-NO are generally potent airway smooth muscle relaxants with at least a partial effect through stimulation of cyclic GMP. Relaxations were attenuated significantly by the guanylate cyclase inhibitor methylene blue (P less than .05), and RS-NO-induced increases in cyclic GMP were demonstrated (P less than .0005). The IC50 values for S-nitroso-glutathione, S-nitroso-cysteine, S-nitroso-homocysteine, S-nitroso-N-acetylcysteine, S-nitroso-penicillamine and S-nitroso-captopril were 0.99 +/- 0.09, 3.2 +/- 0.2, 2.1 +/- 0.3, 2.1 +/- 0.8, 1.8 +/- 0.8 and 20 +/- 0.7 microM (mean +/- S.E.M.), respectively. In this system isoproterenol has an IC50 of 0.016 microM and theophylline an IC50 of 74 microM, making the relaxant properties of these NO derivatives of potential pharmacological and physiological relevance.

CO2 elimination by high frequency ventilation (4 to 10 Hz) in normal subjects

We measured the rate of CO2 elimination (VCO2) by oscillatory high frequency ventilation (HFV) in 8 normal subjects and studied the effects of varying frequency, stroke volume, lung volume, and bronchodilation on VCO2. Subjects breath-held while a loudspeaker at the mouth sinusoidally forced low volumes (15 to 150 ml) of air at a high frequency (4 to 10 Hz) into the respiratory system. The CO2 eliminated from the lungs was washed out by a bias flow at the mouth. In each of 6 subjects studied, VCO2 was greater at 8 Hz than at 4 Hz (130 versus 74 ml/min; p less than 0.05) with oscillation volumes (VT) of 100 ml. At a fixed frequency of 10 Hz there was a positive linear correlation (p less than 0.01) between oscillation volume and VCO2. At a lung volume 500 ml below total lung capacity VCO2 ranged from 130 to 215 ml/min at a mean VT of 130 ml and 5 to 60 ml/min at a VT of only 10% of the estimated anatomic dead space. In 3 subjects, after inhalation of isoproterenol, there was a greater VCO2 over the entire vital capacity (p less than 0.01). We concluded that HFV can achieve values of CO2 elimination close to the estimated metabolic CO2 production in normal unintubated subjects over short periods of time.