A neural network solves, explains, and generates university math problems by program synthesis and few-shot learning at human level.

We demonstrate that a neural network pretrained on text and fine-tuned on code solves mathematics course problems, explains solutions, and generates questions at a human level. We automatically synthesize programs using few-shot learning and OpenAI's Codex transformer and execute them to solve course problems at 81% automatic accuracy. We curate a dataset of questions from Massachusetts Institute of Technology (MIT)'s largest mathematics courses (Single Variable and Multivariable Calculus, Differential Equations, Introduction to Probability and Statistics, Linear Algebra, and Mathematics for Computer Science) and Columbia University's Computational Linear Algebra. We solve questions from a MATH dataset (on Prealgebra, Algebra, Counting and Probability, Intermediate Algebra, Number Theory, and Precalculus), the latest benchmark of advanced mathematics problems designed to assess mathematical reasoning. We randomly sample questions and generate solutions with multiple modalities, including numbers, equations, and plots. The latest GPT-3 language model pretrained on text automatically solves only 18.8% of these university questions using zero-shot learning and 30.8% using few-shot learning and the most recent chain of thought prompting. In contrast, program synthesis with few-shot learning using Codex fine-tuned on code generates programs that automatically solve 81% of these questions. Our approach improves the previous state-of-the-art automatic solution accuracy on the benchmark topics from 8.8 to 81.1%. We perform a survey to evaluate the quality and difficulty of generated questions. This work automatically solves university-level mathematics course questions at a human level and explains and generates university-level mathematics course questions at scale, a milestone for higher education.

Effect of perioperative benzodiazepine use on intraoperative awareness and postoperative delirium: a systematic review and meta-analysis of randomised controlled trials and observational studies.

BACKGROUND: Benzodiazepine use is associated with delirium, and guidelines recommend avoiding them in older and critically ill patients. Their perioperative use remains common because of perceived benefits. METHODS: We searched CENTRAL, MEDLINE, CINAHL, PsycInfo, and Web of Science from inception to June 2021. Pairs of reviewers identified randomised controlled trials and prospective observational studies comparing perioperative use of benzodiazepines with other agents or placebo in patients undergoing surgery. Two reviewers independently abstracted data, which we combined using a random-effects model. Our primary outcomes were delirium, intraoperative awareness, and mortality. RESULTS: We included 34 randomised controlled trials (n=4354) and nine observational studies (n=3309). Observational studies were considered separately. Perioperative benzodiazepines did not increase the risk of delirium (n=1352; risk ratio [RR] 1.43; 95% confidence interval [CI]: 0.9-2.27; I2=72%; P=0.13; very low-quality evidence). Use of benzodiazepines instead of dexmedetomidine did, however, increase the risk of delirium (five studies; n=429; RR 1.83; 95% CI: 1.24-2.72; I2=13%; P=0.002). Perioperative benzodiazepine use decreased the risk of intraoperative awareness (n=2245; RR 0.26; 95% CI: 0.12-0.58; I2=35%; P=0.001; very low-quality evidence). When considering non-events, perioperative benzodiazepine use increased the probability of not having intraoperative awareness (RR 1.07; 95% CI: 1.01-1.13; I2=98%; P=0.03; very low-quality evidence). Mortality was reported by one randomised controlled trial (n=800; RR 0.90; 95% CI: 0.20-3.1; P=0.80; very low quality). CONCLUSIONS: In this systematic review and meta-analysis, perioperative benzodiazepine use did not increase postoperative delirium and decreased intraoperative awareness. Previously observed relationships of benzodiazepine use with delirium could be explained by comparisons with dexmedetomidine. SYSTEMATIC REVIEW PROTOCOL: PROSPERO CRD42019128144.

Clinical history of female-to-male transgender patients is needed to avoid misinterpretation of cervical Papanicolaou tests.

OBJECTIVE: Cervical cancer screening is as important in female-to-male transgender (FTMT) patients as it is in cisgender female patients. The aim of this study was to examine the impact of clinical information regarding gender identity and testosterone therapy on the cytological interpretations. METHODS: A list of FTMT patients and cisgender female patients who had received a cervical Papanicolaou (Pap) test for cancer screening was obtained. The cytological diagnoses, rendered at the time of collection, were recorded. A retrospective slide review with knowledge of the pertinent clinical information, including testosterone therapy status, was performed. The data sets were statistically compared. RESULTS: Of 122 cervical Pap tests in 111 FTMT individuals, 23 (19%) had surgical follow-ups; 73 (60%) had HPV testing, of which 12 (16%) were positive for high-risk strains; and 79 (65%) were known to be receiving testosterone. On the "original" review, 12 (9.8%) tests were diagnosed as unsatisfactory. Seventy-one (58%) Pap tests were initially diagnosed as negative for intraepithelial lesion or malignancy (NILM) without atrophy and 32 (26%) with atrophy. Seven (5.7%) of the tests were initially diagnosed as abnormal. On the "retrospective" review, the rate of unsatisfactory tests remained the same, and atrophy was observed in 76 (62%) tests. The number of abnormal tests was reduced to 4 (3.3%) after the retrospective review. Almost all comparative studies returned a P-value of ≤0.05. CONCLUSION: Our findings indicate that clinical information regarding whether a subject is transgender and/or is receiving testosterone therapy is crucial to avoiding Pap test overcalls.

ERp29 Attenuates Nicotine-Induced Endoplasmic Reticulum Stress and Inhibits Choroidal Neovascularization.

Nicotine-induced endoplasmic reticulum (ER) stress in retinal pigment epithelium (RPE) cells is thought to be one pathological mechanism underlying age-related macular degeneration (AMD). ERp29 attenuates tobacco extract-induced ER stress and mitigates tight junction damage in RPE cells. Herein, we aimed to further investigate the role of ERp29 in nicotine-induced ER stress and choroidal neovascularization (CNV). We found that the expression of ERp29 and GRP78 in ARPE-19 cells was increased in response to nicotine exposure. Overexpression of ERp29 decreased the levels of GRP78 and the C/EBP homologous protein (CHOP). Knockdown of ERp29 increased the levels of GRP78 and CHOP while reducing the viability of ARPE-19 cells under nicotine exposure conditions. In the ARPE-19 cell/macrophage coculture system, overexpression of ERp29 decreased the levels of M2 markers and increased the levels of M1 markers. The viability, migration and tube formation of human umbilical vein endothelial cells (HUVECs) were inhibited by conditioned medium from the ERp29-overexpressing group. Moreover, overexpression of ERp29 inhibits the activity and growth of CNV in mice exposed to nicotine in vivo. Taken together, our results revealed that ERp29 attenuated nicotine-induced ER stress, regulated macrophage polarization and inhibited CNV.

A Systematic Review of Race, Sex, and Socioeconomic Status Differences in Postoperative Pain and Pain Management.

PURPOSE: Optimal postoperative pain management remains a significant problem despite the availability of multiple preoperative, intraoperative, and postoperative pain management interventions. Recent studies suggest that racialized minorities, female sex, and individuals of lower socioeconomic status (SES) are more likely to experience more severe pain and inadequate pain management postoperatively. Our systematic review aimed to determine race, sex, and SES differences in postoperative pain and postoperative pain management. DESIGN: This study is a systematic review of literature. METHODS: Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology, we systematically searched 5 databases: Cumulative Index to Nursing and Allied Health Literature (CINAHL), PubMed, Embase, Scopus, and Cochrane. We included primary source peer-reviewed articles published after 1990 that measured postoperative pain and race/ethnicity, sex/gender, or SES, which were published in English. Two pairs of reviewers independently screened each title, abstract, and article for inclusion. In cases of disagreement, a third reviewer broke the tie. FINDINGS: A total of 464 articles were screened, of which 32 were included in this study. In most studies, Blacks/African American experience more severe postoperative pain than Whites/Caucasians. Whites were more likely to be prescribed opioids for pain management than Blacks, Hispanics, and Asians. Also, individuals of lower SES and females reported more postoperative pain. One study found no race/ethnic group differences in pain scores and opioid use after the implementation of the enhanced recovery after surgery (ERAS) protocol. CONCLUSIONS: Optimal postoperative pain relief continues to be a challenge for individuals who self-identify as racialized minorities, females, and those of lower SES. Standardization of care may help reduce disparities in postoperative pain management.

The applications of cryoneurolysis for acute and chronic pain management.

BACKGROUND: Cryoneurolysis is a term used to describe the application of extreme cold to targeted nerve tissue. The primary goal of the application of a thermal neurolytic technique is to disrupt the conduction of pain signals from the periphery to the central nervous system and eliminate or diminish the experience of pain. Recent advancements in ultrasound technology coupled with the development and approval of handheld devices specifically designed to deliver cryoneurolysis has expanded the use of this modality in the perioperative setting. APPLICATION: Surgical procedures including total knee arthroplasties, shoulder arthroplasties, thoracotomies, and mastectomies have all demonstrated long-term pain relief benefits when cryoneurolysis has been administered days to weeks prior to the planned procedure. In addition, the newly designed handheld device allows for office-based clinical use and has been utilized for various chronic pain conditions including neuropathic and phantom limb pain. CONCLUSION: The evidence clearly demonstrates that cryoneurolysis has a low risk profile and when administered appropriately, provides prolonged analgesia without promoting motor blockade. This narrative review article describes the unique mechanism of action of cryoneurolysis for prolonged pain relief and provides emerging evidence to support its applications in both acute and chronic pain management.

Developmental and interventional plasticity of motor maps after perinatal stroke.

Within the perinatal stroke field, there is a need to establish preclinical models where putative biomarkers for motor function can be examined. In a mouse model of perinatal stroke, we evaluated motor map size and movement latency following optogenetic cortical stimulation against three factors of post-stroke biomarker utility: 1) Correlation to chronic impairment on a behavioral test battery; 2) Amenability to change using a skilled motor training paradigm; 3) Ability to distinguish individuals with potential to respond well to training. Thy1-ChR2-YFP mice received a photothrombotic stroke at postnatal day 7 and were evaluated on a battery of motor tests between days 59-70. Following a cranial window implant, mice underwent longitudinal optogenetic motor mapping both before and after 3 weeks of skilled forelimb training. Map size and movement latency of both hemispheres was positively correlated with impaired spontaneous forelimb use, whereas only ipsilesional hemisphere map size was correlated with performance in skilled reaching. Map size and movement latency did not show groupwise changes with training; however, mice with the smallest pre-training map sizes and worst impairments demonstrated the greatest expansion of map size in response to skilled forelimb training. Overall, motor map size showed utility as a potential biomarker for impairment and training-induced modulation in specific individuals. Future assessment of the predictive capacity of post-stroke motor representations for behavioral outcome in animal models opens the possibility of dissecting how plasticity mechanisms contribute to recovery following perinatal stroke.SIGNIFICANCE STATEMENTWe investigated the utility of two cortical motor representation measures (motor map size and movement onset latency) as potential biomarkers for post-stroke motor recovery in a mouse model of perinatal stroke. Both motor map size and movement latency were associated with functional recovery after perinatal stroke, with map size showing an additional association between training responsiveness and severity of impairment. Overall, both motor map size and movement onset latency show potential as neurophysiological correlates of recovery. As such, future studies of perinatal stroke rehabilitation and neuromodulation should include these measures in order to help explain neurophysiological changes that might be occurring in response to treatment.

AL Lambda Amyloidosis Activates Acute Liver Failure in the Absence of Plasma Cell Dyscrasia.

A patient with systemic amyloidosis developed portal hypertension, acute liver failure and multiorgan dysfunction. Extensive testing was unrevealing for paraproteinemia, plasma cell dyscrasia, infectious, or inflammatory conditions. He was transferred to our institution for orthotopic liver transplant evaluation but was ultimately declined given clinical instability and dysautonomia. Post-mortem evaluation revealed extensive amyloid deposition in multiple organs determined to be AL-lambda amyloidosis.

Rediscovery of Methadone to Improve Outcomes in Pain Management.

Clinically, methadone is most known for its use in the treatment of opioid maintenance therapy. However, methadone's pharmacological profile makes it an excellent analgesic that can enhance acute and chronic pain management. It is a potent µ-receptor agonist with a longer elimination half-life than most clinically used opioids. In addition, methadone inhibits serotonin and norepinephrine uptake, and it is an N-methyl-D-aspartate antagonist. These distinct analgesic pathways mediate hyperalgesic, allodynic, and neuropathic pain. Its unique analgesic properties provide several essential benefits in perioperative use, neuropathic pain, cancer, and noncancer pain. Despite these proven clinical utilities, methadone has not been used widely to treat acute and chronic pain in opioid naïve patients. This article describes the unique pharmacology of methadone and provides emerging evidence to support its application in acute and chronic pain management. Pain management options and guidelines for surgical patients on methadone are discussed as well.

Endothelium-specific deletion of Nox4 delays retinal vascular development and mitigates pathological angiogenesis.

NADPH oxidase 4 (Nox4) is a major isoform of NADPH oxidases playing an important role in many biological processes. Previously we have shown that Nox4 is highly expressed in retinal blood vessels and is upregulated in oxygen-induced retinopathy (OIR). However, the exact role of endothelial Nox4 in retinal angiogenesis remains elusive. Herein, using endothelial cell (EC)-specific Nox4 knockout (Nox4EC-KO) mice, we investigated the impact of endothelial Nox4 deletion on retinal vascular development and pathological angiogenesis during OIR. Our results show that deletion of Nox4 in ECs led to retarded retinal vasculature development with fewer, blunted-end tip cells and sparser, dysmorphic filopodia at vascular front, and reduced density of vascular network in superficial, deep, and intermediate layers in postnatal day 7 (P7), P12, and P17 retinas, respectively. In OIR, loss of endothelial Nox4 had no effect on hyperoxia-induced retinal vaso-obliteration at P9 but significantly reduced aberrant retinal neovascularization at P17 and decreased the deep layer capillary density at P25. Ex vivo study confirmed that lack of Nox4 in ECs impaired vascular sprouting. Mechanistically, loss of Nox4 significantly reduced expression of VEGF, p-VEGFR2, integrin αV, angiopoietin-2, and p-ERK1/2, attenuating EC migration and proliferation. Taken together, our results indicate that endothelial Nox4 is important for retinal vascular development and contributes to pathological angiogenesis, likely through regulation of VEGF/VEGFR2 and angiopoietin-2/integrin αV/ERK pathways. In addition, our study suggests that endothelial Nox4 appears to be essential for intraretinal revascularization after hypoxia. These findings call for caution on targeting endothelial Nox4 in ischemic/hypoxic retinal diseases.

Loss of X-box binding protein 1 in Müller cells augments retinal inflammation in a mouse model of diabetes.

AIMS/HYPOTHESIS: Müller glia (MG) are major sources of retinal cytokines, and their activation is closely linked to retinal inflammation and vascular leakage in diabetic retinopathy. Previously, we demonstrated that X-box binding protein 1 (XBP1), a transcription factor activated by endoplasmic reticulum (ER) stress in diabetic retinopathy, is involved in regulation of inflammation in retinal endothelial cells. Now, we have explored the role of XBP1 and ER stress in the regulation of MG-derived proinflammatory factors, and their influence on vascular permeability in diabetic retinopathy. METHODS: MG-specific conditional Xbp1 knockout (Xbp1Müller-/-) mice were generated by crossing Xbp1 flox/flox mice with Müller-Cre transgenic mice. Diabetes was modelled by induction with streptozotocin, and retinal vascular permeability was measured with FITC-conjugated dextran 2 months after induction. Primary Müller cells were isolated from Xbp1Müller-/- and Xbp1Müller+/+ mice and exposed to hypoxia and high levels of glucose. Levels of ER-stress and inflammatory factors were examined by real-time PCR, western blotting or immunohistochemistry. RESULTS: Xbp1Müller-/- mice exhibited normal retinal development and retinal function and expressed similar levels of ER-stress and inflammatory genes to Xbp1Müller+/+ littermates. In diabetes-inducing conditions, compared with Xbp1Müller+/+ mice, Xbp1Müller-/- mice had higher mRNA levels of retinal Vegf (also known as Vegfa) and Tnf-α (also known as Tnf) and ER-stress marker genes Grp78 (also known as Hspa5), Atf4, Chop (also known as Ddit3) and Atf6 and higher protein levels of vascular endothelial growth factor (VEGF), TNF-α, phospho-c-Jun N-terminal kinase (JNK), 78 kDa glucose-regulated protein (GRP78), phospho-eukaryotic translation initiation factor (eIF)2α and activating transcription factor (ATF)6. Retinal vascular permeability was significantly higher in diabetic Xbp1Müller-/- mice than in diabetic Xbp1Müller+/+ mice (p < 0.01). Results obtained in vitro with primary Müller cells isolated from Xbp1Müller-/- mice confirmed higher expression levels of inflammatory and ER-stress markers (but not GRP78) than in cells from Xbp1Müller+/+ mice. Moreover, XBP1-deficient Müller cells were more susceptible to high-glucose- or hypoxia-induced ER stress and inflammation than cells from Xbp1Müller+/+ mice. Inhibition of ER stress with chemical chaperones suppressed hypoxia-induced VEGF and TNF-α production in XBP1-deficient Müller cells. CONCLUSIONS/INTERPRETATION: Our results have revealed an important role of XBP1 and ER stress in MG-driven retinal inflammation, and suggest that targeting ER stress may represent a promising approach for the prevention and treatment of diabetic retinopathy.

Fossorial Damaraland mole rats do not exhibit a blunted hypercapnic ventilatory response.

Damaraland mole rats (DMRs, Fukomys damarensis) are a eusocial fossorial species that spend the majority of their life in densely populated underground burrows, in which they likely experience intermittent periods of elevated CO2 (i.e. hypercapnia). The primary physiological response to hypercapnia in most mammals is to increase depth and rate of breathing (i.e. hyperpnoea), but this response is often blunted in species that inhabit hypercapnic environments. In their natural habitat, DMRs putatively experience a gaseous environment ranging from normocapnic (0.1% CO2) to hypercapnic (6.0% CO2) conditions (Roper et al. 2001 J. Zool. 254, 101-107). As such, we hypothesized that DMRs would exhibit blunted hypercapnic ventilatory and metabolic responses, relative to those of non-fossorial rodent species. To test this hypothesis, we exposed awake, freely behaving DMRs to normoxic normocapnia (21% O2, 0% CO2, balance N2) or graded normoxic hypercapnia (21% O2, 0, 2, 5, 7 and 10% CO2, balance N2), and measured ventilation and metabolism using whole-body plethysmography and indirect calorimetry, respectively. We found that ventilation and metabolism were unchanged during prolonged normocapnia, whereas during graded hypercapnia, ventilation was elevated at 2% CO2 and above. As a result, O2 extraction efficiency at the lungs decreased with increasing hyperpnoea. Conversely, metabolic rate did not increase until 10% CO2, presumably due to the metabolic cost of hyperpnoea. Taken together, our results suggest that despite their fossorial lifestyle, DMRs do not exhibit adaptations in their ventilatory or metabolic responses to environmental hypercapnia.

Molecular Chaperone ERp29: A Potential Target for Cellular Protection in Retinal and Neurodegenerative Diseases.

The molecular chaperone endoplasmic reticulum protein 29 (ERp29) plays a critical role in protein folding, trafficking, and secretion. Though ubiquitously expressed, ERp29 is upregulated in response to ER stress and is found at higher levels in certain cell types such as secretory epithelial cells and neurons. As an ER resident protein, ERp29 shares many structural and functional similarities with protein disulfide isomerases, but is not regarded as part of this family due to several key differences. The broad expression and myriad roles of ERp29 coupled with its upregulation via the unfolded protein response (UPR) upon ER stress have implicated ERp29 in a range of cellular processes and diseases. We summarize the diverse activities of ERp29 in protein trafficking, cell survival and apoptosis, and ER homeostasis and highlight a potential role of ERp29 in neuroprotection in retinal and neurodegenerative diseases.

Intradermal administration of endothelin-1 attenuates endothelium-dependent and -independent cutaneous vasodilation via Rho kinase in young adults.

We recently showed that intradermal administration of endothelin-1 diminished endothelium-dependent and -independent cutaneous vasodilation. We evaluated the hypothesis that Rho kinase may be a mediator of this response. We also sought to evaluate if endothelin-1 increases sweating. In 12 adults (25 ± 6 yr), we measured cutaneous vascular conductance (CVC) and sweating during 1) endothelium-dependent vasodilation induced via administration of incremental doses of methacholine (0.25, 5, 100, and 2,000 mM each for 25 min) and 2) endothelium-independent vasodilation induced via administration of 50 mM sodium nitroprusside (20-25 min). Responses were evaluated at four skin sites treated with either 1) lactated Ringer solution (Control), 2) 400 nM endothelin-1, 3) 3 mM HA-1077 (Rho kinase inhibitor), or 4) endothelin-1+HA-1077. Pharmacological agents were intradermally administered via microdialysis. Relative to the Control site, endothelin-1 attenuated endothelium-dependent vasodilation (CVC at 2,000 mM methacholine, 80 ± 10 vs. 56 ± 15%max, P < 0.01); however, this response was not detected when the Rho kinase inhibitor was simultaneously administered (CVC at 2,000 mM methacholine for Rho kinase inhibitor vs. endothelin-1 + Rho kinase inhibitor sites: 73 ± 9 vs. 72 ± 11%max, P > 0.05). Endothelium-independent vasodilation was attenuated by endothelin-1 compared with the Control site (CVC, 92 ± 13 vs. 70 ± 14%max, P < 0.01). However, in the presence of Rho kinase inhibition, endothelin-1 did not affect endothelium-independent vasodilation (CVC at Rho kinase inhibitor vs. endothelin-1+Rho kinase inhibitor sites: 81 ± 9 vs. 86 ± 10%max, P > 0.05). There was no between-site difference in sweating throughout (P > 0.05). We show that in young adults, Rho kinase is an important mediator of the endothelin-1-mediated attenuation of endothelium-dependent and -independent cutaneous vasodilation, and that endothelin-1 does not increase sweating.

Activation of protease-activated receptor 2 mediates cutaneous vasodilatation but not sweating: roles of nitric oxide synthase and cyclo-oxygenase.

NEW FINDINGS: What is the central question of this study? Protease-activated receptor 2 (PAR2) is located in the endothelial cells of skin vessels and eccrine sweat glands. However, a functional role of PAR2 in the control of cutaneous blood flow and sweating remains to be assessed in humans in vivo. What is the main finding and its importance? Our results demonstrate that in normothermic resting humans in vivo, activation of PAR2 elicits cutaneous vasodilatation partly through nitric oxide synthase-dependent mechanisms, but does not mediate sweating. These results provide important new insights into the physiological significance of PAR2 in human skin. Protease-activated receptor 2 (PAR2) is present in human skin, including keratinocytes, endothelial cells of skin microvessels and eccrine sweat glands. However, whether PAR2 contributes functionally to the regulation of cutaneous blood flow and sweating remains entirely unclear in humans in vivo. We hypothesized that activation of PAR2 directly stimulates cutaneous vasodilatation and sweating via actions of nitric oxide synthase (NOS) and cyclo-oxygenase (COX). In 12 physically active young men (29 ± 5 years old), cutaneous vascular conductance (CVC) and sweat rate were measured at four intradermal microdialysis forearm skin sites that were treated with the following: (i) lactated Ringer's solution (control); (ii) 10 mm NG -nitro-l-arginine (NOS inhibitor); (iii) 10 mm ketorolac (COX inhibitor); or (iv) a combination of both inhibitors. At all sites, a PAR2 agonist (SLIGKV-NH2 ) was co-administered in a dose-dependent fashion (0.06, 0.18, 0.55, 1.66 and 5 mm, each for 25 min). The highest dose of SLIGKV-NH2 (5 mm) increased CVC from baseline at the control site (P ≤ 0.05). This increase in CVC associated with PAR2 activation was attenuated by NOS inhibition regardless of the presence or absence of simultaneous COX inhibition (both P ≤ 0.05). However, COX inhibition alone did not affect the PAR2-mediated increase in CVC (P > 0.05). No increase in sweat rate was measured at any administered dose of SLIGKV-NH2 (all P > 0.05). We show that in normothermic resting humans in vivo, PAR2 activation does not increase sweat rate, whereas it does modulate cutaneous vasodilatation through NOS-dependent mechanisms.

Nicotinic receptor activation augments muscarinic receptor-mediated eccrine sweating but not cutaneous vasodilatation in young males.

NEW FINDINGS: What is the central question of this study? Acetylcholine released from cholinergic nerves can activate both muscarinic and nicotinic receptors. Although each receptor can independently induce cutaneous vasodilatation and eccrine sweating, it remains to be elucidated whether the two receptors interact in order to mediate these responses. What is the main finding and its importance? We show that although nicotinic receptor activation does not modulate muscarinic cutaneous vasodilatation, it lowers the muscarinic receptor agonist threshold at which onset for eccrine sweating (augmentation of muscarinic eccrine sweating) occurs in young men in normothermic resting conditions. These results provide new insights into the physiological significance of nicotinic receptors in the regulation of cutaneous perfusion and eccrine sweating. Acetylcholine released from cholinergic nerves can activate both muscarinic and nicotinic receptors; each is known independently to induce cutaneous vasodilatation and eccrine sweating in humans. However, it is not known whether the two receptors interact in order to mediate cutaneous vasodilatation and eccrine sweating. In 10 young men (27 ± 6 years old), cutaneous vascular conductance and sweat rate were evaluated at intradermal microdialysis sites that were continuously perfused with either lactated Ringer's solution (control) or three different concentrations of nicotine (0.1, 1 and 10 mm), a nicotinic receptor agonist. Co-administration of methacholine, a muscarinic receptor agonist, was performed at all skin sites in a dose-proportional fashion (0.0125, 0.25, 5, 100 and 2000 mm, each for 25 min). Administration of nicotine alone caused dose-dependent transient increases in cutaneous vascular conductance and sweat rate (all P ≤ 0.05), which thereafter returned to pre-nicotine levels, except that a portion of transient responses remained with continuous administration of 10 mm nicotine (both P ≤ 0.05). Cutaneous vascular conductance was increased by administration of ≥0.25 mm methacholine at the control site, and this response was likewise observed in the presence of co-administration of all doses of nicotine used (all P ≤ 0.05). Sweat rate at the control site was increased by administration of ≥0.25 mm methacholine, but the lowest dose of methacholine (0.0125 mm) was able to increase sweat rate in the presence of 10 mm nicotine (P ≤ 0.05). We conclude that nicotinic receptor activation lowers the muscarinic receptor agonist threshold for eccrine sweating (augmentation of muscarinic sweating) but does not affect muscarinic cutaneous vasodilatation in young men in normothermic resting conditions.

Activation of the UPR protects against cigarette smoke-induced RPE apoptosis through up-regulation of Nrf2.

Recent studies have revealed a role of endoplasmic reticulum (ER) stress-induced unfolded protein response (UPR) in the regulation of RPE cell activity and survival. Herein, we examined the mechanisms by which the UPR modulates apoptotic signaling in human RPE cells challenged with cigarette smoking extract (CSE). Our results show that CSE exposure induced a dose- and time-dependent increase in ER stress markers, enhanced reactive oxygen species (ROS), mitochondrial fragmentation, and apoptosis of RPE cells. These changes were prevented by the anti-oxidant NAC or chemical chaperone TMAO, suggesting a close interaction between oxidative and ER stress in CSE-induced apoptosis. To decipher the role of the UPR, overexpression or down-regulation of XBP1 and CHOP genes was manipulated by adenovirus or siRNA. Overexpressing XBP1 protected against CSE-induced apoptosis by reducing CHOP, p-p38, and caspase-3 activation. In contrast, XBP1 knockdown sensitized the cells to CSE-induced apoptosis, which is likely through a CHOP-independent pathway. Surprisingly, knockdown of CHOP reduced p-eIF2α and Nrf2 resulting in a marked increase in caspase-3 activation and apoptosis. Furthermore, Nrf2 inhibition increased ER stress and exacerbated cell apoptosis, while Nrf2 overexpression reduced CHOP and protected RPE cells. Our data suggest that although CHOP may function as a pro-apoptotic gene during ER stress, it is also required for Nrf2 up-regulation and RPE cell survival. In addition, enhancing Nrf2 and XBP1 activity may help reduce oxidative and ER stress and protect RPE cells from cigarette smoke-induced damage.

K+ channel mechanisms underlying cholinergic cutaneous vasodilation and sweating in young humans: roles of KCa, KATP, and KV channels?

Acetylcholine released from cholinergic nerves is involved in heat loss responses of cutaneous vasodilation and sweating. K(+) channels are thought to play a role in regulating cholinergic cutaneous vasodilation and sweating, though which K(+) channels are involved in their regulation remains unclear. We evaluated the hypotheses that 1) Ca(2+)-activated K(+) (KCa), ATP-sensitive K(+) (KATP), and voltage-gated K(+) (KV) channels all contribute to cholinergic cutaneous vasodilation; and 2) KV channels, but not KCa and KATP channels, contribute to cholinergic sweating. In 13 young adults (24 ± 5 years), cutaneous vascular conductance (CVC) and sweat rate were evaluated at intradermal microdialysis sites that were continuously perfused with: 1) lactated Ringer (Control), 2) 50 mM tetraethylammonium (KCa channel blocker), 3) 5 mM glybenclamide (KATP channel blocker), and 4) 10 mM 4-aminopyridine (KV channel blocker). At all sites, cholinergic cutaneous vasodilation and sweating were induced by coadministration of methacholine (0.0125, 0.25, 5, 100, and 2,000 mM, each for 25 min). The methacholine-induced increase in CVC was lower with the KCa channel blocker relative to Control at 0.0125 (1 ± 1 vs. 9 ± 6%max) and 5 (2 ± 5 vs. 17 ± 14%max) mM methacholine, whereas it was lower in the presence of KATP (69 ± 7%max) and KV (57 ± 14%max) channel blocker compared with Control (79 ± 6%max) at 100 mM methacholine. Furthermore, methacholine-induced sweating was lower at the KV channel blocker site (0.42 ± 0.17 mg·min(-1)·cm(-2)) compared with Control (0.58 ± 0.15 mg·min(-1)·cm(-2)) at 2,000 mM methacholine. In conclusion, we show that KCa, KATP, and KV channels play a role in cholinergic cutaneous vasodilation, whereas only KV channels contribute to cholinergic sweating in normothermic resting humans.