Cover Image,Volume 20, Issue 6

The cover image, by Sara Charleer et al., is based on the Brief Report A vitamin Accuracy and precision of flash glucose monitoring sensors inserted into the abdomen and upper thigh compared with the upper arm, DOI: 10.1111/dom.13239 . Design Credit: Mr. Joren Polfliet.

     

p11 modulates L-DOPA therapeutic effects and dyskinesia via distinct cell types in experimental Parkinsonism

The reduced movement repertoire of Parkinson’s disease (PD) is mainly due to degeneration of nigrostriatal dopamine neurons. Restoration of dopamine transmission by levodopa (L-DOPA) relieves motor symptoms of PD but often causes disabling dyskinesias. Subchronic L-DOPA increases levels of adaptor protein p11 (S100A10) in dopaminoceptive neurons of the striatum. Using experimental mouse models of Parkinsonism, we report here that global p11 knockout (KO) mice develop fewer jaw tremors in response to tacrine. Following L-DOPA, global p11KO mice show reduced therapeutic responses on rotational motor sensitization, but also develop less dyskinetic side effects. Studies using conditional p11KO mice reveal that distinct cell populations mediate these therapeutic and side effects. Selective deletion of p11 in cholinergic acetyltransferase (ChAT) neurons reduces tacrine-induced tremor. Mice lacking p11 in dopamine D2R-containing neurons have a reduced response to L-DOPA on the therapeutic parameters, but develop dyskinetic side effects. In contrast, mice lacking p11 in dopamine D1R-containing neurons exhibit tremor and rotational responses toward L-DOPA, but develop less dyskinesia. Moreover, coadministration of rapamycin with L-DOPA counteracts L-DOPA–induced dyskinesias in wild-type mice, but not in mice lacking p11 in D1R-containing neurons. 6-OHDA lesioning causes an increase of evoked striatal glutamate release in wild type, but not in global p11KO mice, indicating that altered glutamate neurotransmission could contribute to the reduced L-DOPA responsivity. These data demonstrate that p11 located in ChAT or D2R-containing neurons is involved in regulating therapeutic actions in experimental PD, whereas p11 in D1R-containing neurons underlies the development of L-DOPA–induced dyskinesias.Parkinson’s disease (PD) is characterized by a progressive degeneration of dopaminergic neurons projecting from substantia nigra pars compacta (SNc) to striatum, eventually resulting in bradykinesia, rigidity, resting tremor, and postural imbalance (1). Dopamine replacement strategies are effective for many motor symptoms. At early stages, MAO-B inhibitors or dopamine D2 receptor agonists may provide sufficient symptomatic relief, but as the disease progresses essentially all patients will require treatment with levodopa (L-DOPA) (1). Following decarboxylation, L-DOPA is converted to dopamine acting on both dopamine D1 and D2 receptors. D1 and D2 receptors are segregated in striatonigral and striatopallidal pathway neurons, respectively (2). Activation of D1 and D2 receptors causes synergistic stimulation of locomotion, explaining the stronger anti-Parkinsonian action of L-DOPA compared with selective D2 receptor agonists (1, 2). Whereas dopaminergic agents often successfully treat bradykinesia and rigidity in PD, additional therapy with anticholinergic agents is sometimes required for optimal treatment of resting tremor (1). Moreover, the therapeutic effect of L-DOPA is gradually shortened as disabling dyskinetic side effects emerge (3). There is no licensed treatment against L-DOPA–induced dyskinesias (LIDs).Targeting the serotonergic, glutamatergic, and/or cholinergic systems have been reported to counteract LIDs (3). p11 (i.e., S100A10) is a member of the S100 EF-hand protein family, which increase the levels of distinct serotonin (5-HT_1BR and 5-HT₄R) and glutamate (mGluR5) receptors at the cell surface, resulting in enhanced effects on cell signaling via these receptors (4, 5). p11 is widely expressed in the brain with particularly high levels in cholinergic neurons (6–9). p11 is regulated by a variety of stimuli and therapies, most notably antidepressants (4). p11 is strongly up-regulated in the striatum following repeated treatment with L-DOPA in the 6-OHDA–lesioning model of experimental parkinsonism (10). p11 can therefore influence several pathways implicated in LIDs.In the present study, we examined global and cell-specific conditional p11 knockout (KO) mice in experimental Parkinsonism models to identify the brain circuitries that mediate p11-dependent therapeutic effects of L-DOPA as well as LIDs.     

Growth Hormone (GH) Secretion in Primary Adrenal Insufficiency: Effects of Cortisol Withdrawal and Patterned Replacement on GH Pulsatility and Circadian Rhythmicity

We studied the effects of cortisol withdrawal and patterned replacement upon spontaneous GH secretion and circadian rhythmicity in 7 patients with Addison's disease. Hydrocortisone was administered in physiological daily total dosages, and all resulting plasma cortisol values were 2–15 g/dl. It was given in 3 pulsatile modes: simulating physiological rhythm, reverse diurnal rhythmicity and continuous pulsatility. All modes of cortisol administration increased mean 24h, GH pulse amplitude and interpulse GH levels. During saline infusions circadian GH rhythmicity was preserved, with GH being at its highest between 2400–0400 h. Administration of hydrocortisone in any mode did not modify circadian GH rhythmicity. We conclude: Cortisol replacement in physiological daily doses increases GH output in patients with Addison's disease by augmenting GH pulse amplitude and interpulse levels. This is likely due to the attenuation of hypothalamic somatostatin (SRIF) secretion by physiologic levels of cortisol. By inference, it implies that cortisol deficiency leads to diminution of GH output with low GH pulse amplitude, likely as a result of an augmented hypothalamic somatostatin secretion. However, circadian rhythmicity of GH secretion is glucocorticoid-independent.     

Expression and function of KIR and natural cytotoxicity receptors in NK-type lymphoproliferative diseases of granular lymphocytes

Using monoclonal antibodies (mAbs) specific for different natural killer (NK) receptors, we studied the lymphocyte population from 18 patients with NK-type lymphoproliferative disease of granular lymphocytes (LDGL). The analysis of both resting and cultured NK cell populations demonstrated that these patients are frequently characterized by NK cells displaying a homogeneous staining with given anti-killer Ig-like receptor (anti-KIR) mAb (11 of 18 patients). In most patients NK cells were characterized by the CD94/NKG2A+ phenotype, whereas only a minor fraction of the cases expressed CD94/NKG2C. In 7 of these patients we could also assess the function of the various NK receptors. Remarkably those KIR molecules that, in each patient, homogeneously marked the NK cell expansion were found to display an activating function as determined by cross-linking with specific anti-KIR mAb. The KIR genotype analysis performed in 13 of 18 cases revealed that in NK-type LDGL certain activating KIRs, as well as certain infrequent KIR genotypes, were detected with higher frequencies as compared to previously analyzed healthy donors. Moreover, most KIR genotypes included multiple genes coding for activating KIRs. The analysis of non-HLA-specific triggering receptors indicated that the natural cytotoxicity receptors (NKp46, NKp30) were expressed at significantly low levels in freshly drawn NK cells from most patients analyzed. However, in most instances the expression of NKp46 and NKp30 could be up-regulated on culture in interleukin 2. Our data indicate that in NK-LDGL the expanded subset is frequently characterized by the expression of a given activating KIR, suggesting a direct role for these molecules in the pathogenetic mechanisms of this disorder.     

A Ras activation pathway dependent on Syk phosphorylation of protein kinase C

Protein kinase C (PKC) and Syk protein tyrosine kinase play critical roles in immune cell activation including that through the high-affinity IgE receptor, FcepsilonRI. Mechanisms by which PKC activation leads to the activation of Ras, a family of GTPases essential for immune cell activation, have been elusive. We present evidence that Tyr-662 and Tyr-658 of PKCbetaI and PKCalpha, respectively, are phosphorylated by Syk in the membrane compartment of FcepsilonRI-stimulated mast cells. These phosphorylations require prior PKC autophosphorylation of the adjacent serine residues (Ser-661 and Ser-657, respectively) and generate a binding site for the SH2 domain of the adaptor protein Grb-2. By recruiting the Grb-2/Sos complex to the plasma membrane, these conventional PKC isoforms contribute to the full activation of the Ras/extracellular signal-regulated kinase signaling pathway in FcepsilonRI-stimulated mast cells.     

Survival Estimates for Patients with Abnormal Swallowing Studies

OBJECTIVE: To better understand the life expectancy of patients who have an abnormal videofluoroscopic swallowing study. DESIGN: Retrospective cohort study. The common starting point was the time of the severely abnormal swallowing study. Hospital charts were reviewed for clinical variables of potential prognostic significance by reviewers blinded to the outcome of interest, survival time. SETTING: A university-affiliated, community teaching hospital. PATIENTS: One hundred forty-nine hospitalized patients who were deemed nonoral feeders based on their swallowing study. Patients excluded were those with head, neck, or esophageal cancer, or those undergoing a thoracotomy procedure. MEASUREMENTS AND MAIN RESULTS: Clinical and demographic variables and time until death or censoring were measured. Overall 1-year mortality was 62%. Multivariable Cox proportional hazards analyses identified four variables that independently predicted death: advanced age, reduced serum albumin concentration, disorientation to person, and higher Charlson comorbidity score. Eighty patients (54%) subsequently underwent placement of a percutaneous endoscopic gastrostomy (PEG) tube after their swallowing study. CONCLUSIONS: Mortality is high in patients with severely abnormal swallowing studies. Common clinical variables can be used to identify groups of patients with particularly poor prognoses. This information may help guide discussions regarding possible PEG placement.     

Triage decisions for emergency department patients with chest pain

OBJECTIVE: To determine whether physicians’ risk attitudes correlate with their triage decisions for emergency department patients with acute chest pain. DESIGN: Cohort. SETTING: The emergency department of a university teaching hospital. PATIENTS: Patients presenting to the emergency department with a chief complaint of acute chest pain. PHYSICIANS: All physicians who were primarily responsible for the emergency department triage of at least one patient with acute chest pain from July 1990 to July 1991. METHODS: The physicians’ risk attitudes were assessed by two methods: 1) a new, six-question risk-taking scale adapted from the Jackson Personality Index (JPI), and 2) the Stress from Uncertainty Scale (SUS). RESULTS: The physicians who had high risk-taking scores (“risk seekers”) admitted only 31% of the patients they evaluated, compared with admission rates of 44% for the medium scorers and 53% for the physicians who had low risk-taking scores (“risk avoiders”), p<0.001. After adjustment for clinical factors, the patients triaged by the risk-seeking physicians had half the odds of admission [odds ratio (OR) 0.51, 95% confidence interval (95% CI) 0.27 to 0.97], and the patients triaged by the risk-avoiding physicians had nearly twice the odds of admission (OR 1.83, 95% CI 1.10 to 3.03) of the patients triaged by the medium-risk scoring physicians. The SUS did not correlate significantly with admission rates. Of the 92 patients released home by the risk-seeking physicians, 91 (99%) were known to be alive four to six weeks afterwards and one was lost to follow-up; among the 66 patients released by the risk-avoiding physicians, 64 (97%) were known to be alive at four to six weeks, one was lost to follow-up, and one died of ischemic heart disease during a subsequent hospitalization (p=NS). CONCLUSIONS: The physicians’ risk attitudes as measured by a brief risk-taking scale correlated significantly with then-rates of admission for emergency department patients with acute chest pain. These data do not suggest that the risk-seeking physicians achieved lower admission rates by releasing more patients who needed to be in the hospital, but an adequate evaluation of the appropriateness of triage decisions of risk-seeking and risk-avoiding physicians will require further study.     

Soluble HLA class I induces NK cell apoptosis upon the engagement of killer-activating HLA class I receptors through FasL-Fas interaction

The engagement of the activating isoforms of C-type lectin inhibitory receptor (CLIR) or killer Ig-like receptor (KIR) by their natural ligands, represented by soluble HLA-I (sHLA-I) molecules, induced programmed cell death of natural killer (NK) cells. Indeed, NK cell apoptosis elicited by either putative HLA-E and HLA-F (sHLA-I non-A, -B, -C, and -G) or sHLA-I-Cw4 or -Cw3 from untransfected or -Cw4 or -Cw3 alleles transfected HLA-A(-), B(-), C(-), G(-), E(+), F(+) 721.221 lymphoblastoid cell line, respectively, was blocked by covering the corresponding activating receptor with either anti-CLIR- or anti-KIR-specific monoclonal antibodies (mAbs). After sHLA-I-activating receptor interaction, NK cells produced and released Fas ligand (FasL), which in turn led to NK cell apoptosis by interacting with Fas at the NK cell surface. Blocking anti-Fas mAb, or anti-FasL mAb, inhibited sHLA-I-mediated apoptosis via activating receptor in NK cell clones. This apoptosis was inhibited by NK cell treatment with cyclosporin A, whereas this drug had no effect on activating receptor-mediated activation of cytolysis. Conversely, concanamycin A, an inhibitor of vacuolar type H(+)-adenosine triphosphatase (H(+)-ATPase) of granules, inhibited activating receptor-induced NK cell cytolysis, suggesting that activating receptor-mediated apoptosis and cytolysis can use different intracellular pathways. Furthermore, a large amount of interferon-gamma (IFN-gamma) was detectable in culture supernatant of activating receptor(+) NK cells incubated with the appropriate sHLA-I ligand. Again, cyclosporin A, but not concanamycin A, strongly reduced activating receptor-mediated IFN-gamma production. This suggests that activating receptor-induced apoptosis of NK cells could play a role in eliminating potentially harmful NK cell clones and, at the same time, it leads to production of IFN-gamma, an antiviral cytokine able to amplify immune responses.     

Acute Sildenafil Use Reduces 24‐Hour Blood Pressure Levels in Patients With Resistant Hypertension: A Placebo‐Controlled,Crossover Trial

The authors previously demonstrated that acute administration of sildenafil—a phosphodiesterase 5 (PDE5) inhibitor—improves hemodynamic parameters in patients with resistant hypertensive (RH), but its effect on ambulatory blood pressure monitoring (ABPM) is unknown. This interventional, nonrandomized, single‐blinded, placebo‐controlled, crossover trial included 26 patients with RH. A dose of sildenafil (187.5mg) was given, and after a washout period of 14 days the patients received a single oral dose of placebo and the protocol was repeated. The patients underwent 24‐hour ABPM recordings the day before and immediately after the protocols. The reduction of systolic (−8.8±1.4 vs 1.3±1.2 mm Hg, P=.02), diastolic (−5.3±3.3 vs 1.8±1.1 mm Hg, P=.03), and mean (−7.9±3.6 vs 0.8±0.9 mm Hg, P=.01) 24‐hour BP were found after the use of sildenafil compared with placebo. Improvement in daytime BP levels was also observed (systolic −6.0±4.7 vs 4.4±1.5 mm Hg [P=.02] and mean −4.8±3.9 vs 3.5±1.4 mm Hg [P=.02] for sildenafil vs placebo, respectively). Considering its antihypertensive effect, sildenafil may represent a therapeutic option for RH treatment.

The pathogenesis of resistant hypertension (RH) is multifactorial,¹ impacting a worse prognosis when compared with controlled hypertension.² The mechanisms of resistance to antihypertensive therapy are not completely understood and can be modulated by several interrelated factors such as (1) hyperactivation of the sympathetic nervous and renin‐angiotensin‐aldosterone system,³, ⁴ (2) volume expansion,⁵ (3) endothelial dysfunction,⁶, ⁷ (4) inflammatory processes,⁸ and (5) increased peripheral vascular resistance.⁹ Although there is little evidence related to populations with RH, effective blood pressure (BP) control reduces the risk of cardiovascular events in general hypertensive patients and should be targeted.¹⁰ New drug therapies have been proposed, but BP control remains a challenge for patients with RH.¹¹ Phosphodiesterase type 5 (PDE5) inhibitors are safe and effective drugs presenting vasodilatory effects that provide office BP reductions in untreated¹² and resistant hypertensive patients.¹³ Recently, our group has shown an improvement in hemodynamic parameters after acute administration of sildenafil in patients with RH.¹⁴ Although ambulatory BP monitoring (ABPM) is superior to casual BP for predicting organ damage in hypertensive patients,¹⁵, ¹⁶ the influence of sildenafil on ABPM was never assessed in patients with RH.The present study sought to evaluate the effects of sildenafil on ABPM in patients with RH. We hypothesized that acute administration of sildenafil—a PDE5 inhibitor—compared with placebo improves 24‐hour BP levels in patients with resistance to antihypertensive therapy.     

Large-scale mapping of live corals to guide reef conservation

Coral is the life-form that underpins the habitat of most tropical reef ecosystems, thereby supporting biological diversity throughout the marine realm. Coral reefs are undergoing rapid change from ocean warming and nearshore human activities, compromising a myriad of services provided to societies including coastal protection, fishing, and cultural practices. In the face of these challenges, large-scale operational mapping of live coral cover within and across reef ecosystems could provide more opportunities to address reef protection, resilience, and restoration at broad management- and policy-relevant scales. We developed an airborne mapping approach combining laser-guided imaging spectroscopy and deep learning models to quantify, at a large archipelago scale, the geographic distribution of live corals to 16-m water depth throughout the main Hawaiian islands. Airborne estimates of live coral cover were highly correlated with field-based estimates of live coral cover (R² = 0.94). Our maps were used to assess the relative condition of reefs based on live coral, and to identify potential coral refugia in the face of human-driven stressors, including marine heat waves. Geospatial modeling revealed that water depth, wave power, and nearshore development accounted for the majority (>60%) of live coral cover variation, but other human-driven factors were also important. Mapped interisland and intraisland variation in live coral location improves our understanding of reef geography and its human impacts, thereby guiding environmental management for reef resiliency.

Coral is the foundational, habitat-generating life-form of most tropical reefs, but coral is under increasing pressure from marine heat waves, coastal development, and resource extraction (1). Coral change is occurring at multiple ecological scales ranging from genotypic- and species-level responses to broad reef- and regional-level reorganization (2). However, the spatially continuous distribution of live coral cover remains unknown, owing to a scale gap between field and drone-based surveys that sample portions of any given reef and satellite-based approaches that fail to resolve live coral cover from space (3). This gap makes it difficult to map very large regions, such as island archipelagos, at the spatial and biological resolution of the habitat-forming organisms inhabiting these regions.Operational mapping of live coral cover within and across reef ecosystems could provide opportunities for science and management to better address reef protection, resilience, and restoration. For example, reef areas with live coral cover persisting after repeated stressors, such as marine heat waves, may indicate coral refugia (4). Spatial information on refugia may then drive innovations in marine protection as well as scientific investigation of underlying drivers of coral survival (5). In turn, new understanding of survivorship may alter predictions of reef change in the current and forthcoming ocean climate (6, 7). Large-scale information on live coral cover can also inform restoration efforts. Reefs that have lost coral cover from activities such as coastal development could be targeted for restoration if these activities are curtailed. However, low coral cover reefs previously exposed to repeated marine heat waves and severe degradation may represent intractable restoration possibilities (8).The eight main Hawaiian islands (MHIs) are an iconic case in point of regional variability in the face of multiple stressors. Human pressure on Hawaiian reefs is wide-ranging, from relatively low impact on Kahoʻolawe to high impact on Oʻahu (9). Coastal development has resulted in hot spots of sedimentation, waterborne pollutants, and reef removal, while fishing and other resource uses have generated declines in reef resilience (10). In parallel, a series of marine heat waves has nonuniformly engulfed the MHIs, with the 2014, 2015, and 2019 bleaching events being the most recent. The 2015 event generated live coral losses reaching more than 50% in some areas, but the geographic extent of loss or resistance remains unknown (11).The MHIs span a latitude and longitude range of 4° and 6°, respectively, and vary in geologic age, from less than a few years old on parts of Hawaiʻi Island to more than six million years old on Niʻihau (12). Island age is accompanied by stage of accretion and subsidence, processes that generate enormous interisland and intraisland variation in reef extent associated with benthic substrate availability. Combined geophysical and anthropogenic variability across the MHIs has generated ecological complexity in reef composition common to reef systems worldwide.To assess land–sea controls over live coral cover, and to expand options for coral conservation and management, we undertook the first large-scale, high-resolution mapping study of live coral cover across an island archipelago. While there have been extensive in-water surveys of coral reefs in the MHIs, these have been constrained by site access and benthic variability, making the use of field information a challenge to the development of comprehensive regional maps of where live coral exists. Moreover, most airborne or satellite-based approaches derive benthic composition as aggregate classes such as coral combined with algal cover (e.g., refs. 13 and 14), and no programs have operationalized a method to cover large areas (e.g., >1,000 ha) with highly automated mapping of live coral location. We developed an airborne mapping approach that combines laser-guided imaging spectroscopy and computational deep learning to quantify the geographic distribution of live corals to a depth of 16 m. The resulting map was used to assess the relative condition of reefs from a coral perspective, and to identify areas of high live coral cover, deemed potential refugia. Following geospatial analyses of live corals, we used computational machine learning to quantify multiple land–sea drivers affecting live coral cover, as a means to inform mitigation and restoration efforts throughout the MHIs.