Decreasing surface albedo signifies a growing importance of clouds for Greenland Ice Sheet meltwater production.

Clouds regulate the Greenland Ice Sheet's surface energy balance through the competing effects of shortwave radiation shading and longwave radiation trapping. However, the relative importance of these effects within Greenland's narrow ablation zone, where nearly all meltwater runoff is produced, remains poorly quantified. Here we use machine learning to merge MODIS, CloudSat, and CALIPSO satellite observations to produce a high-resolution cloud radiative effect product. For the period 2003-2020, we find that a 1% change in cloudiness has little effect (±0.16 W m-2) on summer net radiative fluxes in the ablation zone because the warming and cooling effects of clouds compensate. However, by 2100 (SSP5-8.5 scenario), radiative fluxes in the ablation zone will become more than twice as sensitive (±0.39 W m-2) to changes in cloudiness due to reduced surface albedo. Accurate representation of clouds will therefore become increasingly important for forecasting the Greenland Ice Sheet's contribution to global sea-level rise.

Storage and export of microbial biomass across the western Greenland Ice Sheet.

The Greenland Ice Sheet harbours a wealth of microbial life, yet the total biomass stored or exported from its surface to downstream environments is unconstrained. Here, we quantify microbial abundance and cellular biomass flux within the near-surface weathering crust photic zone of the western sector of the ice sheet. Using groundwater techniques, we demonstrate that interstitial water flow is slow (~10-2 m d-1), while flow cytometry enumeration reveals this pathway delivers 5 × 108 cells m-2 d-1 to supraglacial streams, equivalent to a carbon flux up to 250 g km-2 d-1. We infer that cellular carbon accumulation in the weathering crust exceeds fluvial export, promoting biomass sequestration, enhanced carbon cycling, and biological albedo reduction. We estimate that up to 37 kg km-2 of cellular carbon is flushed from the weathering crust environment of the western Greenland Ice Sheet each summer, providing an appreciable flux to support heterotrophs and methanogenesis at the bed.

Exploring the active ingredients of workplace physical and psychological wellbeing programs: a systematic review.

Previous reviews have established that workplace wellbeing initiatives are effective at promoting wellbeing, but less is known about which intervention characteristics or "active ingredients" underpin this effectiveness (i.e., behavior change techniques [BCTs]). This review aims to illuminate the connections between the types of BCTs and the level of intervention intensity with intervention effectiveness. A systematic search for peer-reviewed studies evaluating a workplace wellbeing initiative was undertaken across five databases: Medline, Scopus, PsycInfo, and CINAHL (Ovid Emcare). Eligible studies included those that evaluated the effect of a workplace wellbeing initiative on participants' physical wellbeing (e.g., physical activity and quality of life) and psychological wellbeing (e.g., mental health and stress), were published between 2009 and September 2019, and utilized a comparator (e.g., control group or prepost change). Studies were screened in independent duplicate to minimize bias. Effect sizes were calculated. Following removal of duplicates, 1,541 studies were identified and screened for eligibility. Of these, 23 studies reporting 28 comparisons were deemed to meet eligibility criteria. Just over 50% of these studies reported evidence of either a strong or moderate effect across a physical and a psychological outcome, providing a positive indication that workplace wellbeing programs can promote physical and psychological wellbeing in workers. Interventions tended to employ multiple BCTs (mean range 8.1-9.4), however, no discernible patterns between the types or numbers of BCTs employed and intervention effectiveness was found. Further experimental work is required that compares and contrasts workplace wellbeing initiatives to enable a better understanding of how to develop and implement highly effective programs.

Greenland Ice Sheet surface melt amplified by snowline migration and bare ice exposure.

Greenland Ice Sheet mass loss has recently increased because of enhanced surface melt and runoff. Since melt is critically modulated by surface albedo, understanding the processes and feedbacks that alter albedo is a prerequisite for accurately forecasting mass loss. Using satellite imagery, we demonstrate the importance of Greenland's seasonally fluctuating snowline, which reduces ice sheet albedo and enhances melt by exposing dark bare ice. From 2001 to 2017, this process drove 53% of net shortwave radiation variability in the ablation zone and amplified ice sheet melt five times more than hydrological and biological processes that darken bare ice itself. In a warmer climate, snowline fluctuations will exert an even greater control on melt due to flatter ice sheet topography at higher elevations. Current climate models, however, inaccurately predict snowline elevations during high melt years, portending an unforeseen uncertainty in forecasts of Greenland's runoff contribution to global sea level rise.

Treatment of paediatric trigger finger: a systematic review and treatment algorithm.

PURPOSE: Paediatric trigger finger (PTF) is a rare condition as seen by the lack of studies published about paediatric populations. Due to this general lack of information, the steps to employ to correct this disorder, whether surgically or non-surgically, have not yet reached consensus status. The objective of this study is to review the published literature regarding treatment options for PTF in order to develop a proposed step-wise treatment algorithm for children presenting with trigger finger. METHODS: A systematic review of the literature was conducted on PubMed to locate English language studies reporting on treatment interventions of PTF. Data was collected on number of patients/fingers seen in the study, the category of the fingers involved, the number of patients/fingers undergoing each intervention and reported outcomes. RESULTS: Seven articles reporting on 118 trigger fingers were identified. In all, 64 fingers were treated non-surgically, with 57.8% (37/64) resolving. In all, 54 fingers were initially surgically treated, with 87% (47/54) resolving. In total, 34 fingers did not have resolution of symptoms following primary treatment, and 27 fingers received follow-up treatment, with 92.6% (25/27) resolving. Overall, 92.4% (109/118) of fingers achieved resolution of symptoms after all treatments were completed. CONCLUSION: Limitations for this study included few prospective studies and small sample sizes. This is likely due to the rarity of PTF. This review of the literature indicated that a step-wise approach, including non-operative and surgical techniques, should be employed in the management of PTF. LEVEL OF EVIDENCE III: This work meets the requirements of the PRISMA guidelines (Preferred Reporting Items for Systematic Reviews and Meta-Analyses).

Sudden hearing loss following non-petrous craniotomy.

We present two patients with known otosclerosis undergoing craniotomy for conditions unrelated to the temporal bone who experienced sudden sensorineural hearing loss. In both patients, the hearing loss was noted immediately post-operatively and there was no subsequent recovery. Sudden hearing loss is a rare complication of non-otologic, non-cardiopulmonary bypass surgery. To our knowledge it has not been described in patients with otosclerosis undergoing craniotomy. This is a rare event that may occur in patients with vulnerable ears, such as those with otosclerosis or pre-existing sensorineural hearing loss.

Role of cricothyroid cannulation in head and neck surgery.

OBJECTIVES: This paper outlines our use of cricothyroid cannulation in those patients undergoing head and neck surgery in whom a 'difficult airway' is anticipated. Audit results are presented. MATERIALS AND METHODS: Prospective data collection for all patients undergoing cricothyroid cannulation for management of head and neck neoplasms, over a two-year period. RESULTS: Thirty-nine cricothyroid cannulae were sited in 32 patients. All patients with laryngeal tumours underwent the procedure while awake, prior to the anticipated difficult intubation, and the cannulae were removed within six hours. Most cannulations performed under general anaesthetic were for anticipated 'dangerous extubations' in patients with oral cavity tumours, and these cannulae remained in place for 24 hours. Tracheostomy was possibly avoided in six patients. No complications were identified. CONCLUSION: Cricothyroid cannulation can be a simple, safe, reliable technique which is a useful adjunct in the management of patients with a potentially difficult airway.

Acute phase gene expression in mice exposed to the marine neurotoxin domoic acid.

Domoic acid is a rigid analog of the neurotransmitter glutamate and a potent agonist of kainate subtype glutamate receptors. Persistent activation of these receptor subtypes results in rapid excitotoxicity, calcium dependent cell death and neuronal lesions in areas of the brain where kainate pathways are concentrated. To better understand responses to domoic acid induced excitotoxicity, microarrays were used to profile gene expression in mouse brain following domoic acid exposure. Adult female mice were subjected intraperitoneally to domoic acid at the lethal dose 50, killed and dissected at 30, 60 and 240 min post-injection. Total brain RNA from treated mice was compared with time-matched controls on Agilent 22K feature microarrays. Real-time PCR was performed on selected genes. For the 30, 60 and 240 min time points, 3.96%, 3.94% and 4.36% of the genes interrogated were differentially expressed (P-value < or = 0.01), respectively. Rigorous filtering of the data resulted in a set of 56 genes used for trending analysis and K-medians and agglomerative clustering. The earliest genes induced consisted primarily of early response gene families (Jun, Fos, Ier, Egr, growth arrest and DNA damage 45) and the inflammatory response element cyclooxygenase 2. Some later responding genes involved glucocorticoid responses (Gilz, Sgk), cold inducible proteins (Cirbp, Rbm3), Map kinases (Map3k6) and NF-kappaB inhibition. Real-time PCR in male mice from an additional study confirmed the expression of several of these genes across gender. The transcriptional profile induced by domoic acid shared similarity with expression profiles of brain ischemia and other excitotoxins, suggesting a common transcriptional response.

A visual pigment expressed in both rod and cone photoreceptors.

Rods and cones contain closely related but distinct G protein-coupled receptors, opsins, which have diverged to meet the differing requirements of night and day vision. Here, we provide evidence for an exception to that rule. Results from immunohistochemistry, spectrophotometry, and single-cell RT-PCR demonstrate that, in the tiger salamander, the green rods and blue-sensitive cones contain the same opsin. In contrast, the two cells express distinct G protein transducin alpha subunits: rod alpha transducin in green rods and cone alpha transducin in blue-sensitive cones. The different transducins do not appear to markedly affect photon sensitivity or response kinetics in the green rod and blue-sensitive cone. This suggests that neither the cell topology or the transducin is sufficient to differentiate the rod and the cone response.

MHC class I molecules on adenovirus E1A-expressing tumor cells inhibit NK cell killing but not NK cell-mediated tumor rejection.

Expression of adenovirus E1A gene products in tumor cells enhances NK cell lysis in vitro and NK-mediated rejection in vivo, despite increasing class I molecules on tumor cells. It is unclear why the increased expression of MHC class I molecules does not appear to confer resistance to killing by NK cells. One possibility is the unique capacity of E1A to sensitize cells to multiple NK cell killing mechanisms including perforin/granzyme, Fas ligand, tumor necrosis factor-alpha and TRAIL. To examine this issue, MCA-102-E1A tumor cells (H-2(b)) that express E1A and are NK sensitive were transfected with H-2D(d), the ligand for the NK inhibitory receptor, Ly49A. Expression of H-2D(d) molecules by MCA-102-E1A cells protected them from lysis by a Ly49A(+) NK cell clone and Ly49A(+) NK cells isolated from C57BL/6 nude mice. In contrast, NK cell-mediated rejection of MCA-102-E1A tumor cells was not inhibited by the expression of H-2D(d) molecules, nor was killing by polyclonal populations of NK cells isolated from C57BL/6-nude mice. H-2D(d) interacts with several inhibitory Ly49 receptors that are non-clonally expressed on NK cells in C57BL/6 mice: Ly49A (20% of NK cells), Ly49G2 (54% of NK cells) and Ly49C/I (47% of NK cells). Our data indicate that while E1A sensitizes cells to NK cell killing, it does not interfere with signal transduction by inhibitory NK receptors. Therefore, a small population of NK cells that do not express Ly49A, Ly49G2 or Ly49C/I inhibitory receptors are likely responsible for the rejection of MCA-102-E1A-D(d) tumor cells in vivo.

Cloning and characterization of three salamander retinal G-protein beta subunits.

PURPOSE: Recent evidence has shown that the beta-gamma dimers (beta gamma) of activated heterotrimeric G-proteins are important in many cellular signaling pathways. Since two distinct transducin alpha subunits have been cloned from the salamander retina, we aimed to identify and characterize the G-protein beta (Gbeta) subunits that are involved in visual signal transduction in the salamander. METHODS: A salamander retina cDNA library was screened using degenerate oligonucleotide primers designed from a compilation of known Gbeta sequences. Tissue specific expression was determined by reverse transcriptase PCR (RT-PCR). RESULTS: The library screening resulted in the cloning of three full-length sequences, two of which encode proteins of 340 residues and the third being an iniation variant of 353 and 395 residues. No identical matches were found in GenBank but each shows highest homology to G-beta-1 (beta1), G-beta-3 (beta3), and G-beta-5 (beta5 and beta5L) subunits of other species, respectively. The beta1 and beta3 subunits are 84.7% identical to each other but both show only 52% identity to beta5 at the protein level. RT-PCR analysis showed that all the subunits are expressed in multiple tissues, including the retina. However, the beta5L splice variant was found only in the retina. CONCLUSIONS: Three distinct Gbeta subunit transcripts are expressed in the salamander retina. These subunits have proven to be important in the visual system of mammalian models.

Salamander UV cone pigment: sequence, expression, and spectral properties.

The visual pigment from the ultraviolet (UV) cone photoreceptor of the tiger salamander has been cloned, expressed, and characterized. The cDNA contains a full-length open reading frame encoding 347 amino acids. The phylogenetic analysis indicates that the highest sequence homology is to the visual pigments in the S group. The UV opsin was tagged at the carboxy-terminus with the sequence for the 1D4 epitope. This fusion opsin was expressed in COS-1 cells, regenerated with 11-cis retinal (A1) and immuno-purified, yielding a pigment with an absorbance maximum (lambdamax) of 356 nm which is blue shifted from the absorption of retinal itself. The transducin activation assay demonstrated that this pigment is able to activate rod transducin in a light-dependent manner. Regeneration with 11-cis 3,4-dehydroretinal (A2) yielded a pigment with a lambdamax of 360 nm, only 4 nm red shifted from that of the A1 pigment, while bovine rhodopsin generated with A2 showed a 16-nm red shift from the corresponding A1 pigment. These results demonstrate that the trend for a shorter wavelength pigment to have a smaller shift of lambdamax between the A1 and A2 pigments also fits UV pigments. We hypothesize that the small red shift with A2 could be due to a twist in the chromophore that essentially isolates the ring double bond(s) from conjugation with the rest of the polyene chain.

Physiologic functions of activating natural killer (NK) complex-encoded receptors on NK cells.

Natural killer (NK) cells express a superfamily of surface proteins that share common structural features: dimeric type II integral membrane proteins with extracellular domains resembling C-type lectins. These receptors are encoded by a single genetic region called the NK complex (NKC). The NKC encompasses several families of genes including NKR-PI, Ly-49, CD94/NKG2, and NKG2D. Different NKC-encoded receptors have been shown to activate or to inhibit NK-cell function, and different receptors within the same family can have opposing functions. Within an individual NK cell, inhibitory receptors typically predominate over stimulatory receptors, calling into question the teleologic requirement or physiologic significance of lectin-like activating receptors in NK cells. Despite the widespread expression of inhibitory receptors, however, subtle features of activating receptor biology enable them to stimulate effector functions in vivo and in vitro. Activating receptors and inhibitory receptors differ in their subset expression, in their structural constraints for binding to common ligands, in their ligand repertoires, and in that divergent families of activating receptors utilize different signaling pathways. These subset, binding, repertoire, and signaling diversities may allow activating receptors to manifest their effects in spite of inhibitory receptor functions during pathologic conditions in vivo. In this review, we will present a detailed analysis of the data supporting this hypothesis with particular relevance toward physiologic NK-cell functions.

Rat natural killer cell receptor systems and recognition of MHC class I molecules.

Rat natural killer (NK) cells recognize MHC-I molecules encoded by both the classical (RT1-A) and non-classical (RT1-C/E/M) MHC class I (MHC-I) regions. We have identified a receptor, the STOK2 antigen, which belongs to the Ly-49 family of killer cell lectin-like receptors, and we have localized the gene encoding it to the rat natural killer cell gene complex. We have also shown that it inhibits NK cytotoxicity when recognizing its cognate MHC-I ligand RT1-A1c on a target cell. This is the first inhibitory Ly-49-MHC-I interaction identified in the rat and highlights the great similarity between rat and mouse Ly-49 receptors and their MHC ligands. However, the mode of rat NK-cell recognition of target cells indicates that positive recognition of allo-MHC determinants, especially those encoded by the RT1-C/E/M region, is a prevalent feature. NK cells recruited to the peritoneum as a consequence of alloimmunization display positive recognition of allodeterminants. In one case, NK cells activated in this way have been shown to be specific for the immunizing, non-classical class I molecule RT1-Eu. These findings show that allospecific NK cells sometimes show features reminiscent of the adaptive immune response.

Cloning and characterization of a novel mouse myeloid DAP12-associated receptor family.

The presence of a negatively charged residue in the transmembrane domain of DAP12 precludes its cell surface expression in the absence of a partner receptor containing a positive charge in its transmembrane domain. We utilized this property of DAP12 to screen a BALB / c macrophage cDNA library for novel molecules that induce cell surface expression of DAP12. By this method, we cloned a cell surface receptor with a single Ig (V) domain, a transmembrane lysine residue, and a short cytoplasmic domain. By homology screening of BALB / c macrophage libraries, we identified a second cDNA for a highly homologous receptor. These receptors appear to be the mouse orthologues of a recently identified human cDNA, TREM-2, so we have designated the receptors as mouse TREM-2a and TREM-2b. By Northern blotting, transcripts for TREM-2 were found in each of three macrophage cell lines but not in a variety of other hematopoietic cell lines. We further demonstrate that TREM-2a is associated with endogenous DAP12 in macrophage cells, and cross-linking of TREM-2a on the surface of macrophages leads to the release of nitric oxide. Our studies define TREM-2 as a receptor family in mouse macrophages and demonstrate the capacity of these receptors to activate macrophage function through DAP12.

Expression of the platelet receptor GPVI confers signaling via the Fc receptor gamma -chain in response to the snake venom convulxin but not to collagen.

The mechanism of signal transduction underlying the activation of platelets by collagen has been actively investigated for over 30 years, but the receptors involved remain incompletely understood. Studies of human platelets, which are unresponsive to collagen, mouse knockout models, and platelet biochemical studies support the hypothesis that the recently cloned platelet surface protein GPVI functions as a signaling receptor for collagen. To directly test this hypothesis, we have expressed wild-type and mutant forms of GPVI in RBL-2H3 cells, which express the Fcepsilon receptor gamma-chain (Fc Rgamma), the putative signaling co-receptor for GPVI in platelets, but lack GPVI itself. Expression of GPVI in RBL-2H3 cells confers strong adhesive and signaling responses to convulxin (a snake venom protein that directly binds GPVI) and weak responsiveness to collagen-related peptide but no responsiveness to collagen. To elucidate the mechanism of GPVI intracellular signaling, mutations were introduced in the receptor's transmembrane domain and C-terminal tail. Unlike reported studies of other Fc Rgamma partners, these studies reveal that both the GPVI transmembrane arginine and intracellular C-tail are necessary for coupling to Fc Rgamma and for signal transduction. To our knowledge, these studies are the first to demonstrate a direct signaling role for GPVI and the first to directly test the role of GPVI as a collagen receptor. Our results suggest that GPVI may be necessary but not sufficient for collagen signaling and that a distinct ligand-binding collagen receptor such as the alpha(2)beta(1) integrin is likely to play a necessary role for collagen signaling as well as adhesion in platelets.

Characterization and molecular cloning of rat C1qRp, a receptor on NK cells.

Here we report the generation of monoclonal antibodies (mAb) LOV3 and LOV8 to a 110-130-kDa membrane glycoprotein expressed by rat NK cells. This NK surface molecule was identified by eucaryotic expression cloning as the structural orthologue of the phagocytosis-stimulating receptor for complement factor C1q and mannose-binding lectin on human macrophages, C1qRp. Rat C1qRp is a monomeric type I integral membrane protein consisting of 643 amino acids with an N-terminal lectin-like domain, five epidermal growth factor-like domains, a transmembrane domain and a 45-residue cytoplasmic domain. It is encoded by a single gene on rat chromosome 3q41-q42 and is 67% and 87.5% identical at the amino acid level to human and mouse C1qRp, respectively. Rat C1qRp is expressed by resting and by activated NK cells, on subpopulations of NKR-P1(+) T cells (NK/T cells), dendritic cells, macrophages and granulocytes, but not by B cells or NKR-P1(-) T cells. Expression of this innate immune receptor is therefore not restricted to hematopoietic cells of the myeloid lineage, but is also expressed on subsets of cells of lymphoid origin. The mAb did not affect the cytotoxic function of NK cells, and C1qRp on NK cells may have functions not related to NK killing.

Activating Ly-49D and inhibitory Ly-49A natural killer cell receptors demonstrate distinct requirements for interaction with H2-D(d).

The activating Ly-49D receptor and the inhibitory Ly-49A receptor mediate opposing effects on natural killer (NK) cell cytotoxicity after interaction with the same major histocompatibility complex ligand, H2-D(d). To compare Ly-49D and Ly-49A interactions with H2-D(d), we created mutations in H2-D(d) and examined the functional ability of these mutants to activate lysis through Ly-49D or to inhibit lysis through Ly-49A. Specific single amino acid changes in either the H2-D(d) alpha(1) helix or the alpha(2) helix abrogated Ly-49D-mediated cytotoxicity, but these changes had no significant effect on Ly-49A-dependent inhibition. Each of three alpha(2) domain mutations in the floor of the peptide binding groove reduced functional recognition by either Ly-49D or Ly-49A, but all three were required to fully abrogate inhibition by Ly-49A. Our studies indicate that Ly-49D/H2-D(d) interactions require distinct determinants compared with Ly-49A/H2-D(d) interactions. These differences have important implications for the integration of activating and inhibitory signals in NK cells.