Effect of LKB1 deficiency on mitochondrial content, fibre type and muscle performance in the mouse diaphragm

AIM

The liver kinase B1 (LKB1)/AMP-activated protein kinase (AMPK) signalling pathway is a major regulator of skeletal muscle metabolic processes. During exercise, LKB1-mediated phosphorylation of AMPK leads to its activation, promoting mitochondrial biogenesis and glucose transport, among other effects. The roles of LKB1 and AMPK have not been fully characterized in the diaphragm.

METHODS

Two methods of AMPK activation were used to characterize LKB1/AMPK signalling in diaphragms from muscle-specific LKB1 knockout (KO) and littermate control mice: (1) acute injection of 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR) and (2) 5-min direct electrical stimulation of the diaphragm. Diaphragms were excised 60 min post-AICAR injection and immediately after electrical stimulation.

RESULTS

AMPK phosphorylation increased with AICAR and electrical stimulation in control but not KO mice. Acetyl CoA carboxylase phosphorylation increased with AICAR in control but not KO mice, but increased in both genotypes with electrical stimulation. While the majority of mitochondrial protein levels were lower in KO diaphragms, uncoupling protein 3, complex I and cytochrome oxidase IV protein levels were not different between genotypes. KO diaphragms have a lower percentage of IIx fibres and an elevated percentage of IIb fibres when compared with control diaphragms. While in vitro peak force generation was similar between genotypes, KO diaphragms fatigued more quickly and had an impaired ability to recover.

CONCLUSION

LKB1 regulates AMPK phosphorylation, mitochondrial protein expression, fibre type distribution, as well as recovery of the diaphragm from fatigue.

The effect of age on avian influenza viral shedding in mallards (Anas platyrhynchos)

Avian influenza virus (AIV) prevalence in wild aquatic bird populations varies with season, geographic location, host species, and age. It is not clear how age at infection affects the extent of viral shedding. To better understand the influence of age at infection on viral shedding of wild bird-origin low pathogenicity avian influenza (LPAI) viruses, mallards (Anas platyrhynchos) of increasing age (2 wk, 1 mo, 2 mo, 3 mo, and 4 mo) were experimentally inoculated via choanal cleft with a 10(6) median embryo infectious dose (EID50) of either A/Mallard/MN/355779/00 (H5N2) or A/Mallard/MN/199106/99 (H3N8). Exposed birds in all five age groups were infected by both AIV isolates and excreted virus via the oropharynx and cloaca. The 1-month and older groups consistently shed virus from 1 to 4 d post inoculation (dpi), whereas, viral shedding was delayed by 1 d in the 2-wk-old group. Past 4 dpi, viral shedding in all groups varied between individual birds, but virus was isolated from some birds in each group up to 21 dpi when the trial was terminated. The 1-mo-old group had the most productive shedding with a higher number of cloacal swabs that tested positive for virus over the study period and lower cycle threshold values on real-time reverse-transcription PCR. The viral shedding pattern observed in this study suggests that, although mallards from different age groups can become infected and shed LPAI viruses, age at time of infection might have an effect on the extent of viral shedding and thereby impact transmission of LPAI viruses within the wild bird reservoir system. This information may help us better understand the natural history of these viruses, interpret field and experimental data, and plan future experimental trials.

Screening to identify mental health problems in pediatric primary care: considerations for practice

OBJECTIVE

Few pediatric primary care providers routinely use mental health screening tools, in part because they may have concerns about whether screening is useful and how it will affect their practice. This study examined the extent to which screening in primary care would increase the identification of mental health problems among a diverse population of children and youth.

METHODS

Prior to the visit, the parents of 767 patients age 5 to 16 completed the Strengths and Difficulties Questionnaire to report their child's mental health symptoms and impairment. Without viewing the screening results, each child's provider (N = 53) completed a questionnaire to report whether the child or youth demonstrated a mental health problem.

RESULTS

Compared with providers, the screen identified twice as many patients with moderate symptoms and nearly 28% more patients with high symptoms. Among patients with high symptoms, providers failed to identify a problem among 78% of those who were Latino/Other and 55% of those who were African American compared with 27% of Caucasian patients (p < 0.001). Providers were not more likely to identify patients with externalizing versus internalizing symptoms but were more likely to identify patients who demonstrated symptoms across multiple domains of functioning.

CONCLUSIONS

Screening substantially increased the number of children and youth who would be identified as possibly having a mental health problem. Screening may have the most potential to increase the identification of problems among patients who have moderate mental health symptoms and those who are African American or Latino.

Deletion of the alpha-arrestin protein Txnip in mice promotes adiposity and adipogenesis while preserving insulin sensitivity

OBJECTIVE

Thioredoxin interacting protein (Txnip), a regulator of cellular oxidative stress, is induced by hyperglycemia and inhibits glucose uptake into fat and muscle, suggesting a role for Txnip in type 2 diabetes pathogenesis. Here, we tested the hypothesis that Txnip-null (knockout) mice are protected from insulin resistance induced by a high-fat diet.

RESEARCH DESIGN AND METHODS

Txnip gene-deleted (knockout) mice and age-matched wild-type littermate control mice were maintained on a standard chow diet or subjected to 4 weeks of high-fat feeding. Mice were assessed for body composition, fat development, energy balance, and insulin responsiveness. Adipogenesis was measured from ex vivo fat preparations, and in mouse embryonic fibroblasts (MEFs) and 3T3-L1 preadipocytes after forced manipulation of Txnip expression.

RESULTS

Txnip knockout mice gained significantly more adipose mass than controls due to a primary increase in both calorie consumption and adipogenesis. Despite increased fat mass, Txnip knockout mice were markedly more insulin sensitive than controls, and augmented glucose transport was identified in both adipose and skeletal muscle. RNA interference gene-silenced preadipocytes and Txnip(-/-) MEFs were markedly adipogenic, whereas Txnip overexpression impaired adipocyte differentiation. As increased adipogenesis and insulin sensitivity suggested aspects of augmented peroxisome proliferator-activated receptor-gamma (PPARgamma) response, we investigated Txnip's regulation of PPARgamma function; manipulation of Txnip expression directly regulated PPARgamma expression and activity.

CONCLUSIONS

Txnip deletion promotes adiposity in the face of high-fat caloric excess; however, loss of this alpha-arrestin protein simultaneously enhances insulin responsiveness in fat and skeletal muscle, revealing Txnip as a novel mediator of insulin resistance and a regulator of adipogenesis.

Pediatric primary care as a component of systems of care

Systems of care should be defined in a manner that includes primary care. The current definition of systems of care shares several attributes with the definition of primary care: both are defined as community-based services that are accessible, accountable, comprehensive, coordinated, culturally competent, and family focused. However, systems of care is defined as serving only children and youth with serious emotional disturbance and their families and does not fully embrace the concept of primary prevention. Although similarities in the definitions of primary care and systems of care may provide a theoretical foundation for including primary care within the systems of care framework, a definition of systems of care that incorporates the idea of prevention and takes into account the broad population served in primary care would provide communities with a definition that can be used to further the work of integrating primary care into systems of care.

Employer demand for health services researchers in the year 2020

OBJECTIVE

To describe factors that will shape future demand for doctoral-trained health services researchers. STUDY DESIGN/DATA SOURCES: Commentary based on recent trends in funding for health services research (HSR), the number of federally funded HSR projects listed in HSRProj, national expenditures for health, and interviews with a small number of employers.

PRINCIPAL FINDINGS

Despite rapid growth in the overall health care sector, inflation-adjusted funding for HSR has declined, implying little or no net growth in demand for people to lead HSR studies. Employers report being able to hire researchers to conduct HSR by drawing on people trained in many disciplines.

CONCLUSION

Employers have considerable flexibility in hiring individuals to conduct HSR when demand is relatively stable. They may have much more difficulty hiring well-qualified researchers when faced with sharp increases in demand for HSR, such as could be generated by recent economic stimulus legislation.

Tenacity of avian influenza viruses

The goal of this review is to provide an overview of existing research on the environmental tenacity of avian influenza (AI) viruses, to identify gaps in our current understanding, and discuss how this information relates to AI control, eradication, and prevention. We are just beginning to understand the environmental factors that affect infectivity and the extent of variation in environmental tenacity that is present among these viruses. Because the environment can provide a bridge for AI virus transmission between many diverse hosts, including wild and domestic animals and man, understanding the importance of environmental transmission and identifying important points of contact are critical steps in preventing the spread of infection especially related to the introduction of these viruses to new host species.

5-hydroxyindalpine, an agonist at the putative 5-HT receptor, has no activity on human recombinant monoamine receptors but accelerates distension-induced peristalsis in mouse isolated colon

Although the putative 5-HT(1P) receptor has been implicated to have a role in peristalsis, experiments which suggest this function are preliminary or have measured only components of the reflex. We have, therefore, further characterized a reported agonist at this receptor (5-hydroxyindalpine; 5-OHIP) and investigated the effects of 5-OHIP and 5-hydroxytrytophan-dipeptide (5-HTP-DP), a reported 5-HT(1P) receptor antagonist, on distension-induced peristalsis in mouse colon. The effects of 5-OHIP on intracellular calcium, cyclic adenosine monophosphate concentrations or GTPgammaS binding were measured in cell lines expressing human recombinant 5-HT(1A, 1B, 1D, 2A, 2B, 2C, 3, 4, 6, 7) and alpha(1A), alpha(1B), D(1), D(2), D(3), H(1), H(3) receptors. The effects of 5-OHIP and 5-HTP-DP on peristalsis were assessed by measuring changes in frequency and times to reach threshold of peristaltic contractions, as well as the threshold and maximum pressures of each peristaltic stroke. 5-hydroxyindalpine (1 nmol L(-1)-10 micromol L(-1)) had no significant activity at any of the receptors studied. However, 5-OHIP (0.1 nmol L(-1)-1 micromol L(-1)) concentration-dependently increased the frequency of peristalsis (EC(50) = 4.4 nmol L(-1)) and reduced the time taken to reach threshold and threshold pressure, without altering maximum pressures. The maximum effect of 5-OHIP was at 1 micromol L(-1) (68.0 +/- 14.5% increase in frequency); 10 micromol L(-1) decreased peristalsis. 5-hydroxytrytophan-dipeptide (1-300 nmol L(-1)) also increased the frequency of peristalsis and prevented the actions of 5-OHIP. The higher concentration (1 micromol L(-1)) transiently inhibited peristalsis and after recovery, prevented the actions of 5-OHIP but not the excitatory activity of the cholinesterase inhibitor neostigmine. In summary, the present data demonstrate an interaction of '5-HT(1P)-ligands' with the peristaltic reflex. However, the absence of an effect of 5-OHIP on a range of different monoamine receptors continues to highlight the need to investigate the identity of the putative 5-HT(1P) receptor.

Inhibition of colonic motility and defecation by RS-127445 suggests an involvement of the 5-HT2B receptor in rodent large bowel physiology

BACKGROUND

5-HT(2B) receptors are localized within the myenteric nervous system, but their functions on motor/sensory neurons are unclear. To explore the role of these receptors, we further characterized the 5-HT(2B) receptor antagonist RS-127445 and studied its effects on peristalsis and defecation.

EXPERIMENTAL APPROACH

Although reported as a selective 5-HT(2B) receptor antagonist, any interactions of RS-127445 with 5-HT(4) receptors are unknown; this was examined using the recombinant receptor and Biomolecular Interaction Detection technology. Mouse isolated colon was mounted in tissue baths for isometric recording of neuronal contractions evoked by electrical field stimulation (EFS), or under an intraluminal pressure gradient to induce peristalsis; the effects of RS-127445 on EFS-induced and on peristaltic contractions were measured. Faecal output of rats in grid-bottom cages was measured over 3 h following i.p. RS-127445 and separately, validation of the effective doses was achieved by determining the free, unbound fraction of RS-127445 in blood and brain.

KEY RESULTS

RS-127445 (up to 1 micromol x L(-1)) did not interact with the 5-HT(4) receptor. RS-127445 (0.001-1 micromol x L(-1)) did not affect EFS-induced contractions of the colon, although at 10 micromol x L(-1) the contractions were reduced (to 36 +/- 8% of control, n= 4). RS-127445 (0.1-10 micromol x L(-1)) concentration-dependently reduced peristaltic frequency (n= 4). RS-127445 (1-30 mg x kg(-1)), dose-dependently reduced faecal output, reaching significance at 10 and 30 mg x kg(-1) (n= 6-11). In blood and brain, >98% of RS-127445 was protein-bound.

CONCLUSIONS AND IMPLICATIONS

High-protein binding of RS-127445 indicates that relatively high doses are required for efficacy. The results suggest that 5-HT(2B) receptors tonically regulate colonic motility.

AMP-activated protein kinase response to contractions and treatment with the AMPK activator AICAR in young adult and old skeletal muscle

One characteristic of ageing skeletal muscle is a decline in mitochondrial function. Activation of AMP-activated protein kinase (AMPK) occurs in response to an increased AMP/ATP ratio, which is one potential result of mitochondrial dysfunction. We have previously observed higher AMPK activity in old (O; 30 months) vs young adult (YA; 8 months) fast-twitch muscle in response to chronic overload. Here we tested the hypothesis that AMPK would also be hyperactivated in O vs YA fast-twitch extensor digitorum longus muscles from Fischer(344) x Brown Norway (FBN) rats (n = 8 per group) in response to high-frequency electrical stimulation of the sciatic nerve (HFES) or injection of AICAR, an activator of AMPK. Muscles were harvested immediately after HFES (10 sets of six 3-s contractions, 10 s rest between contractions, 1 min rest between sets) or 1 h after AICAR injection (1 mg (g body weight)(-1) subcutaneously). The phosphorylations of AMPKalpha and acetyl-CoA carboxylase (ACC2; a downstream AMPK target) were both greatly increased (P <or= 0.05) in response to HFES in O muscles, but were either unresponsive (AMPK alpha) or much less responsive (ACC) in YA muscles. AMPK alpha2 activity was also greatly elevated in response to HFES in O muscles (but not YA muscles) despite a lower total AMPK alpha2 protein content in O vs YA muscles. In contrast, AMPK alpha2 activity was equally responsive to AICAR treatment in both age groups. Since mitochondrial content and/or efficiency could potentially underlie AMPK hyperactivation, we measured levels of mitochondrial proteins as well as citrate synthase (CS) activity. While CS activity was increased by 25% in O vs YA muscles, uncoupling protein-3 (UCP-3) protein level was upregulated with age by 353%. Thus, AMPK hyperactivation in response to contractile activity in aged fast-twitch muscle may be the result of compromised cellular energetics and not necessarily due to an inherent defect in responsiveness of the AMPK molecule per se.

Oral administration of a centrally acting ghrelin receptor agonist to conscious rats triggers defecation

Agonists of ghrelin receptors that cross the blood-brain barrier, but not ghrelin itself, administered peripherally (intravenous or subcutaneous), cause defecation by acting on centres in the lumbo-sacral spinal cord. It is not established whether orally administered ghrelin receptor agonists can have this action. We tested GSK894281 for its effectiveness at the ghrelin receptor and its ability to cross the blood-brain barrier. GSK894281 was effective at the human and rat ghrelin receptors at 1-10 nmol L(-1), but was >1000-fold less potent at the motilin receptor. It achieved a similar blood concentration by oral or intravenous administration. Oral bioavailability was 74% and brain : blood ratio at steady state was 0.7 : 1. GSK894281 administered orally (1-100 mg kg(-1)) caused a prompt, dose-related production of faecal pellets; at 10 mg kg(-1) faecal output was four times greater than after carrier. The output was the greatest in the first half hour and subsided over the next 90 min. At an oral dose of 10 mg kg(-1), the compound was effective on eight successive days. Faecal output was, on average, increased threefold over control in the 2 h after administration on each of the 8 days. This dose also significantly increased food consumption. Rats showed no adverse behavioural effects to the drug on a single application, but at the end of a week of administration they avoided the gavaging pipette. Oral administration of ghrelin receptor agonists that enter the central nervous system could possibly be used to relieve acute cases of constipation or to clear the bowel for colonoscopy.

Discussion of sensitive health topics with youth during primary care visits: relationship to youth perceptions of care

PURPOSE

Youth have concerns about sensitive health topics, such as drugs, sex, and mental health, and many wish to discuss those concerns with a primary care provider. Research has not determined whether the discussion of sensitive health topics during primary care visits is independently associated with youth perceptions of care. This study examined whether the discussion of sensitive health topics during primary care visits was associated with youth's perceptions of the provider and of participation in treatment.

METHODS

Directly after visits to 54 primary care providers in 13 geographically diverse offices and clinics, youth age 11-16 years old (N = 358) reported whether the visit included the discussion of mood, behavior, getting along with others, drugs, tobacco, alcohol, sexuality, birth control, parent mood, or family problems. Youth also reported whether the provider understood their problems, eased their worries, allowed them to make decisions about treatment, gave them some control over treatment, and asked them to take some responsibility for treatment. Providers reported confidence in their ability to offer counseling for nonmedical concerns and their beliefs and attitudes toward treating nonmedical concerns.

RESULTS

Youth had more positive perceptions of the provider and were more likely to report taking an active role in treatment when the visit included the discussion of a sensitive health topic. Results from multivariate random effects logistic regression suggested that youth were more likely to report that the provider understood their problems (OR = 3.62, CI = 1.57-8.31), eased their worries (OR = 2.13, CI = 1.06-3.92), allowed them to make decisions about treatment (OR = 2.71, CI = 1.44-5.10), gave them some control over treatment (OR = 2.51, CI = 1.32-4.71), and asked them to take some responsibility for treatment (OR = 2.00, CI = 1.04-3.86) when the visit included the discussion of one or more sensitive health topics. The odds of each of these outcomes were also higher when the visit included the discussion of a greater number of sensitive topics. Youth also had more positive perceptions of female providers. Youth demographics, mental health status, and other provider characteristics were unrelated to youth perceptions of care.

CONCLUSIONS

The discussion of sensitive health topics during primary care visits may have a positive impact on youth perceptions of care. Future research is needed to understand the relationship between the discussion of sensitive health topics and health outcomes among youth.

PPARgamma in the endothelium regulates metabolic responses to high-fat diet in mice

Although endothelial dysfunction, defined as abnormal vasoreactivity, is a common early finding in individuals with type 2 diabetes, the endothelium has not been known to regulate metabolism. As PPARgamma, a transcriptional regulator of energy balance, is expressed in endothelial cells, we set out to investigate the role of endothelial cell PPARgamma in metabolism using mice that lack PPARgamma in the endothelium and BM (gammaEC/BM-KO). When gammaEC/BM-KO mice were fed a high-fat diet, they had decreased adiposity and increased insulin sensitivity compared with control mice, despite increased serum FFA and triglyceride (TG) levels. After fasting or olive oil gavage, gammaEC/BM-KO mice exhibited significant dyslipidemia and failed to respond to the FFA and TG lowering effects of the PPARgamma agonist rosiglitazone. BM transplantation studies, which reconstituted hematopoietic PPARgamma, established that these metabolic phenotypes were due to endothelial PPARgamma deficiency. We further found that the impairment in TG-rich lipoprotein metabolism in gammaEC/BM-KO mice was associated with fatty acid-mediated lipoprotein lipase inhibition and changes in a PPARgamma-regulated endothelial cell transcriptional program. Despite their metabolic improvements, high-fat diet-fed gammaEC/BM-KO mice had impaired vasoreactivity. Taken together, these data suggest that PPARgamma in the endothelium integrates metabolic and vascular responses and may contribute to the effects of PPARgamma agonists, thus expanding what endothelial function and dysfunction may entail.

Disagreement in parent and primary care provider reports of mental health counseling

OBJECTIVES

The goals were to examine disagreement in primary care provider and parent reports of mental health counseling and to determine whether disagreement was associated with provider, parent, youth, and visit characteristics.

METHODS

Directly after 749 visits to 54 pediatric primary care providers in 16 practices, the parents of youths 5 to 16 years of age and the providers independently reported whether mental health counseling was provided. The parent also reported child mental health symptoms, the reason for the visit, and his or her attitudes about receiving treatment for child mental health problems in primary care. The provider reported confidence in his or her mental health treatment skills, burden and beliefs associated with treating mental health problems, and the accessibility of mental health specialists.

RESULTS

Providers reported delivering counseling during 31.9% of visits (n=239), whereas parents reported receiving counseling during only 11.4% of visits (n=86). Parents did not report receiving counseling during 74.8% of the visits in which the provider reported delivering counseling; this was more common when the parent was seeking help for a mental health problem, when the provider reported greater burden associated with treating mental health problems, and when the youth had more mental health symptoms or was of other race/Hispanic. Provider report of counseling in the absence of parent report of counseling was less common when the provider had greater access to mental health specialists.

CONCLUSIONS

Parents often did not report that the counseling delivered in primary care was mental health treatment. Counseling that is not perceived as mental health treatment may fail to meet parent expectations for care or fail to help parents identify mental health problems.

Discussion of maternal stress during pediatric primary care visits

OBJECTIVE

To determine whether the discussion of maternal stress in pediatric primary care is associated with the mother's satisfaction with her child's provider.

METHODS

Children ages 5-16 and their mothers (N=747) were recruited from the waiting rooms of 13 geographically diverse pediatric primary care sites from 2002 to 2005. Directly after the visit, the mother reported her satisfaction with the attention that the provider gave to her and her child's problems and also reported whether the provider understood the problems that she wanted to discuss during the visit. The mother also reported whether the visit included discussion of her "stresses and strains" and the discussion of child mood or behavior.

RESULTS

Thirty-five percent of mothers discussed their stresses and strains with their child's provider. The mother was more likely to be "completely" satisfied with the attention that she and her child received from the provider (odds ratio [OR] 2.43, 95% confidence interval [95% CI], 1.43-4.11) and to agree "strongly" that the provider understood the problems she wanted to discuss (OR 1.95, 95% CI, 1.32-2.93) when the visit included the discussion of maternal stress after controlling for the reason for the visit, number of previous visits, provider specialty (family practice or pediatrics), youth mental health status, whether the visit included the discussion of child mood or behavior, and maternal distress measured with a standard screening tool.

CONCLUSIONS

The mother was more satisfied with her child's primary care provider when maternal stress was discussed during the visit. This finding should somewhat alleviate fears that mothers will react negatively to discussion of their stress during pediatric visits.

Thyroid hormone effects on LKB1, MO25, phospho-AMPK, phospho-CREB, and PGC-1alpha in rat muscle

Expression of all of the isoforms of the subunits of AMP-activated protein kinase (AMPK) and AMPK activity is increased in skeletal muscle of hyperthyroid rats. Activity of AMPK in skeletal muscle is regulated principally by the upstream kinase, LKB1. This experiment was designed to determine whether the increase in AMPK activity is accompanied by increased expression of the LKB1, along with binding partner proteins. LKB1, MO25, and downstream targets were determined in muscle extracts in control rats, in rats given 3 mg of thyroxine and 1 mg of triiodothyronine per kilogram chow for 4 wk, and in rats given 0.01% propylthiouracil (PTU; an inhibitor of thyroid hormone synthesis) in drinking water for 4 wk (hypothyroid group). LKB1 and MO25 increased in the soleus of thyroid hormone-treated rats vs. the controls. In other muscle types, LKB1 responses were variable, but MO25 increased in all. In soleus, MO25 mRNA increased with thyroid hormone treatment, and STRAD mRNA increased with PTU treatment. Phospho-AMPK and phospho-ACC were elevated in soleus and gastrocnemius of hyperthyroid rats. Thyroid hormone treatment also increased the amount of phospho-cAMP response element binding protein (CREB) in the soleus, heart, and red quadriceps. Four proteins having CREB response elements (CRE) in promoter regions of their genes (peroxisome proliferator-activated receptor-gamma coactivator-1alpha, uncoupling protein 3, cytochrome c, and hexokinase II) were all increased in soleus in response to thyroid hormones. These data provide evidence that thyroid hormones increase soleus muscle LKB1 and MO25 content with subsequent activation of AMPK, phosphorylation of CREB, and expression of mitochondrial protein genes having CRE in their promoters.

AMP-activated protein kinase phosphorylates transcription factors of the CREB family

AMP-activated protein kinase (AMPK) has been identified as a regulator of gene transcription, increasing mitochondrial proteins of oxidative metabolism as well as hexokinase expression in skeletal muscle. In mice, muscle-specific knockout of LKB1, a component of the upstream kinase of AMPK, prevents contraction- and 5-aminoimidazole-4-carboxamide-1-beta-D-ribofuranoside (AICAR)-induced activation of AMPK in skeletal muscle, and the increase in hexokinase II protein that is normally observed with chronic AICAR activation of AMPK. Since previous reports show a cAMP response element in the promoter region of the hexokinase II gene, we hypothesized that the cAMP-response element (CRE) binding protein (CREB) family of transcription factors could be targets of AMPK. Using radioisotopic kinase assays, we found that recombinant and rat liver and muscle AMPK phosphorylated CREB1 at the same site as cAMP-dependent protein kinase (PKA). AMPK was also found to phosphorylate activating transcription factor 1 (ATF1), CRE modulator (CREM), and CREB-like 2 (CREBL2), but not ATF2. Treatment of HEK-293 cells stably transfected with a CREB-driven luciferase reporter with AICAR increased luciferase activity approximately threefold over a 24-h time course. This increase was blocked with compound C, an AMPK inhibitor. In addition, AICAR-induced activation of AMPK in incubated rat epitrochlearis muscles resulted in an increase in both phospho-acetyl-CoA carboxylase and phospho-CREB. We conclude that CREB and related proteins are direct downstream targets for AMPK and are therefore likely involved in mediating some effects of AMPK on expression of genes having a CRE in their promoters.

LKB1 and the regulation of malonyl-CoA and fatty acid oxidation in muscle

5'-AMP-activated protein kinase (AMPK), by way of its inhibition of acetyl-CoA carboxylase (ACC), plays an important role in regulating malonyl-CoA levels and the rate of fatty acid oxidation in skeletal and cardiac muscle. In these tissues, LKB1 is the major AMPK kinase and is therefore critical for AMPK activation. The purpose of this study was to determine how the lack of muscle LKB1 would affect malonyl-CoA levels and/or fatty-acid oxidation. Comparing wild-type (WT) and skeletal/cardiac muscle-specific LKB1 knockout (KO) mice, we found that the 5-aminoimidazole-4-carboxamide-1-beta-d-ribofuranoside (AICAR)-stimulated decrease in malonyl-CoA levels in WT heart and quadriceps muscles was entirely dependent on the presence of LKB1, as was the AICAR-induced increase in fatty-acid oxidation in EDL muscles in vitro, since these responses were not observed in KO mice. Likewise, the decrease in malonyl-CoA levels after muscle contraction was attenuated in KO gastrocnemius muscles, suggesting that LKB1 plays an important role in promoting the inhibition of ACC, likely by activation of AMPK. However, since ACC phosphorylation still increased and malonyl-CoA levels decreased in KO muscles (albeit not to the levels observed in WT mice), whereas AMPK phosphorylation was entirely unresponsive, LKB1/AMPK signaling cannot be considered the sole mechanism for inhibiting ACC during and after muscle activity. Regardless, our results suggest that LKB1 is an important regulator of malonyl-CoA levels and fatty acid oxidation in skeletal muscle.

Physician and patient characteristics associated with discussion of psychosocial health during pediatric primary care visits

This study examined whether physical pain, mental health symptoms, and provider characteristics were associated with the discussion of children's behavior, mood, getting along with others, school performance, family stress, and parent stress during 800 pediatric primary care visits to 54 providers in 13 clinics. The discussion of psychosocial health was more common when the child demonstrated hyperactivity symptoms, the visit was for a mental health problem, and the provider was a woman or reported greater confidence in mental health treatment skills, but less common when the child demonstrated physical pain. Provider gender, psychosocial orientation, the reason for the visit, and the child's characteristics did not explain the inverse relationship between pain and discussion. This suggests that multilevel factors that describe the child and provider are associated with the discussion of psychosocial health, and that pain interferes with discussion during all types of visits and during visits with children who are impaired by mental health symptoms.

Peroxisome proliferator-activated receptors as transcriptional nodal points and therapeutic targets

Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors involved in the transcriptional regulation of key metabolic pathways such as lipid metabolism, adipogenesis, and insulin sensitivity. More recent work implicates all 3 PPAR isotypes (alpha, gamma, and delta, also known as beta or beta/delta) in inflammatory and atherosclerotic pathways. Because these nuclear receptors are activated by extracellular signals and control multiple gene targets, PPARs can be seen as nodes that control multiple inputs and outputs involved in energy balance, providing insight into how metabolism and the vasculature may be integrated. The ongoing clinical use of fibrates, which activate PPARalpha, and thiazolidinediones, which activate PPARgamma, establishes these receptors as viable drug targets, whereas considerable in vitro animal model and human surrogate marker studies suggest that PPAR activation may limit inflammation and atherosclerosis. Together, these various observations have stimulated intense interest in PPARs as therapeutic targets and led to large-scale cardiovascular end-point trials with PPAR agonists. The first of these studies has generated mixed results that require careful review, especially in anticipation of additional clinical trial data and ongoing attempts to develop novel PPAR modulators. Such analysis of the existing PPAR data, the appropriate use of currently approved PPAR agonists, and continued progress in PPAR therapeutics will be predicated on a better understanding of PPAR biology.

Identification of youth psychosocial problems during pediatric primary care visits

This investigation applied the Gateway Provider Model (GPM) of child mental health services to investigate whether characteristics of the child, family, visit, and provider were related to the identification of youth psychosocial problems during primary care visits. Data were gathered during 774 visits to 54 primary care providers (PCPs) at 13 clinics. Similar to previous investigations in primary care settings, 42% of youth demonstrated at least a sub-threshold clinical mental health problem. Most PCPs reported high job satisfaction and control, but reported varying access to mental health specialists. PCPs generally had positive attitudes and beliefs about treating psychosocial problems but many reported that doing so was burdensome. Identification was more likely when the visit was for a mental health problem, when issues related to psychosocial problems were discussed during the visit, when the youth demonstrated mental health symptoms, impairment, or burden to the family, and when the youth was older, uninsured, or received Medicaid. Identification was less likely when the PCP reported greater burden associated with treating psychosocial problems and when the PCP reported greater accessibility to mental health specialists. These results suggest that identification is associated with the interaction of multilevel factors and that the GPM is a useful model to investigate points of intervention for improving the identification of children's mental health problems in primary care settings.

Parent and teacher mental health ratings of children using primary-care services: interrater agreement and implications for mental health screening

OBJECTIVE

To examine interrater agreement when screening for child mental health problems during primary-care visits.

METHODS

Children aged 5 to 10 (n = 227) and one of their parents were systematically recruited from the waiting rooms of 15 primary-care sites located in Baltimore, Md; Washington, DC; and rural New York from 2002 to 2005. The parent and teacher of the child completed the Strengths and Difficulties Questionnaire to measure the child's emotions, behaviors, and functional impairment.

RESULTS

Parents and teachers identified a similar proportion of children as having high symptoms (25% vs 23%) and high impairment (27% vs 32%) but rarely agreed in their assessments of specific children. Parent ratings alone missed 52% of children rated by teachers as having both high symptoms and high impairment (kappa = 0.15). Only 6% of these discrepant visits were for mental health problems, making it unlikely that teacher reports would have been solicited.

CONCLUSIONS

Parent reports failed to detect half of school-aged children considered to be seriously disturbed by their teachers. Efforts to improve detection of mental health problems by using screening tools in primary care may require algorithms that help providers judge when to solicit teacher reports and how to interpret conflicting information from parents and teachers.