Disorders of Potassium

Abnormalities in serum potassium are commonly encountered in patients presenting to the emergency department. A variety of acute and chronic causes can lead to life-threatening illness in both hyperkalemia and hypokalemia. Here we summarize the relevant causes, risks, and treatment options for these frequently encountered disorders.

BioSimulators: a central registry of simulation engines and services for recommending specific tools

Computational models have great potential to accelerate bioscience, bioengineering, and medicine. However, it remains challenging to reproduce and reuse simulations, in part, because the numerous formats and methods for simulating various subsystems and scales remain siloed by different software tools. For example, each tool must be executed through a distinct interface. To help investigators find and use simulation tools, we developed BioSimulators (https://biosimulators.org), a central registry of the capabilities of simulation tools and consistent Python, command-line and containerized interfaces to each version of each tool. The foundation of BioSimulators is standards, such as CellML, SBML, SED-ML and the COMBINE archive format, and validation tools for simulation projects and simulation tools that ensure these standards are used consistently. To help modelers find tools for particular projects, we have also used the registry to develop recommendation services. We anticipate that BioSimulators will help modelers exchange, reproduce, and combine simulations.

A community challenge to evaluate RNA-seq, fusion detection, and isoform quantification methods for cancer discovery

The accurate identification and quantitation of RNA isoforms present in the cancer transcriptome is key for analyses ranging from the inference of the impacts of somatic variants to pathway analysis to biomarker development and subtype discovery. The ICGC-TCGA DREAM Somatic Mutation Calling in RNA (SMC-RNA) challenge was a crowd-sourced effort to benchmark methods for RNA isoform quantification and fusion detection from bulk cancer RNA sequencing (RNA-seq) data. It concluded in 2018 with a comparison of 77 fusion detection entries and 65 isoform quantification entries on 51 synthetic tumors and 32 cell lines with spiked-in fusion constructs. We report the entries used to build this benchmark, the leaderboard results, and the experimental features associated with the accurate prediction of RNA species. This challenge required submissions to be in the form of containerized workflows, meaning each of the entries described is easily reusable through CWL and Docker containers at https://github.com/SMC-RNA-challenge. A record of this paper's transparent peer review process is included in the supplemental information.

Disaster Diagnoses in Geriatric Patients with Abdominal Pain

Care of geriatric patients with abdominal pain can pose significant diagnostic and therapeutic challenges to emergency physicians. Older adults rarely present with classic signs, symptoms, and laboratory abnormalities. The incidence of life-threatening emergencies, including abdominal aortic aneurysm, mesenteric ischemia, perforated viscus, and other surgical emergencies, is high. This article explores the evaluation and management of several important causes of abdominal pain in geriatric patients with an emphasis on high-risk presentations.

36-year-old Male with Syncope

CASE PRESENTATION

A 36-year-old incarcerated male presented to the emergency department (ED) after an episode concerning for syncope. The patient had nystagmus and ataxia on initial examination.

DISCUSSION

There is a broad differential diagnosis for syncope, and for patients presenting to the ED we tend to focus on cardiogenic and neurologic causes. This case takes the reader through the differential diagnosis and systemic work-up of a patient presenting to the ED with syncope.

Exploring Integrative Analysis Using the BioMedical Evidence Graph

PURPOSE

The analysis of cancer biology data involves extremely heterogeneous data sets, including information from RNA sequencing, genome-wide copy number, DNA methylation data reporting on epigenetic regulation, somatic mutations from whole-exome or whole-genome analyses, pathology estimates from imaging sections or subtyping, drug response or other treatment outcomes, and various other clinical and phenotypic measurements. Bringing these different resources into a common framework, with a data model that allows for complex relationships as well as dense vectors of features, will unlock integrated data set analysis.

METHODS

We introduce the BioMedical Evidence Graph (BMEG), a graph database and query engine for discovery and analysis of cancer biology. The BMEG is unique from other biologic data graphs in that sample-level molecular and clinical information is connected to reference knowledge bases. It combines gene expression and mutation data with drug-response experiments, pathway information databases, and literature-derived associations.

RESULTS

The construction of the BMEG has resulted in a graph containing > 41 million vertices and 57 million edges. The BMEG system provides a graph query-based application programming interface to enable analysis, with client code available for Python, Javascript, and R, and a server online at bmeg.io. Using this system, we have demonstrated several forms of cross-data set analysis to show the utility of the system.

CONCLUSION

The BMEG is an evolving resource dedicated to enabling integrative analysis. We have demonstrated queries on the system that illustrate mutation significance analysis, drug-response machine learning, patient-level knowledge-base queries, and pathway level analysis. We have compared the resulting graph to other available integrated graph systems and demonstrated the former is unique in the scale of the graph and the type of data it makes available.

Evaluation of the Renal Transplant Recipient in the Emergency Department

Renal transplants are becoming more and more frequent in the United States and worldwide. Studies demonstrate that these patients inevitably end up visiting an emergency department. In addition to typical medical and surgical problems encountered in the general population, this group of patients has unique problems arising from their immunocompromised state and also due to side effects of the medications required. This article discusses these risks and management decisions that the emergency department physician should be aware of in order to prevent adverse outcomes for the patient and transplanted kidney.

Mice lacking the transcriptional regulator Bhlhe40 have enhanced neuronal excitability and impaired synaptic plasticity in the hippocampus

Bhlhe40 is a transcription factor that is highly expressed in the hippocampus; however, its role in neuronal function is not well understood. Here, we used Bhlhe40 null mice on a congenic C57Bl6/J background (Bhlhe40 KO) to investigate the impact of Bhlhe40 on neuronal excitability and synaptic plasticity in the hippocampus. Bhlhe40 KO CA1 neurons had increased miniature excitatory post-synaptic current amplitude and decreased inhibitory post-synaptic current amplitude, indicating CA1 neuronal hyperexcitability. Increased CA1 neuronal excitability was not associated with increased seizure severity as Bhlhe40 KO relative to +/+ (WT) control mice injected with the convulsant kainic acid. However, significant reductions in long term potentiation and long term depression at CA1 synapses were observed in Bhlhe40 KO mice, indicating impaired hippocampal synaptic plasticity. Behavioral testing for spatial learning and memory on the Morris Water Maze (MWM) revealed that while Bhlhe40 KO mice performed similarly to WT controls initially, when the hidden platform was moved to the opposite quadrant Bhlhe40 KO mice showed impairments in relearning, consistent with decreased hippocampal synaptic plasticity. To investigate possible mechanisms for increased neuronal excitability and decreased synaptic plasticity, a whole genome mRNA expression profile of Bhlhe40 KO hippocampus was performed followed by a chromatin immunoprecipitation sequencing (ChIP-Seq) screen of the validated candidate genes for Bhlhe40 protein-DNA interactions consistent with transcriptional regulation. Of the validated genes identified from mRNA expression analysis, insulin degrading enzyme (Ide) had the most significantly altered expression in hippocampus and was significantly downregulated on the RNA and protein levels; although Bhlhe40 did not occupy the Ide gene by ChIP-Seq. Together, these findings support a role for Bhlhe40 in regulating neuronal excitability and synaptic plasticity in the hippocampus and that indirect regulation of Ide transcription may be involved in these phenotypes.

In a randomized trial in prostate cancer patients, dietary protein restriction modifies markers of leptin and insulin signaling in plasma extracellular vesicles

Obesity, metabolic syndrome, and hyperleptinemia are associated with aging and age-associated diseases including prostate cancer. One experimental approach to inhibit tumor growth is to reduce dietary protein intake and hence levels of circulating amino acids. Dietary protein restriction (PR) increases insulin sensitivity and suppresses prostate cancer cell tumor growth in animal models, providing a rationale for clinical trials. We sought to demonstrate that biomarkers derived from plasma extracellular vesicles (EVs) reflect systemic leptin and insulin signaling and respond to dietary interventions. We studied plasma samples from men with prostate cancer awaiting prostatectomy who participated in a randomized trial of one month of PR or control diet. We found increased levels of leptin receptor in the PR group in total plasma EVs and in a subpopulation of plasma EVs expressing the neuronal marker L1CAM. Protein restriction also shifted the phosphorylation status of the insulin receptor signal transducer protein IRS1 in L1CAM+ EVs in a manner suggestive of improved insulin sensitivity. Dietary PR modifies indicators of leptin and insulin signaling in circulating EVs. These findings are consistent with improved insulin and leptin sensitivity in response to PR and open a new window for following physiologic responses to dietary interventions in humans.

Abdominal emergencies in the geriatric patient

Abdominal pain is one of the most frequent reasons that elderly people visit the emergency department (ED). In this article, we review the deadliest causes of abdominal pain in this population, including mesenteric ischemia, abdominal aortic aneurysm, and appendicitis and potentially lethal non-abdominal causes. We also highlight the pitfalls in diagnosing, or rather misdiagnosing, these clinical entities.

Interposition arthroplasty options for carpometacarpal arthritis of the thumb

Carpometacarpal (CMC) arthritis of the thumb affects half of postmenopausal women and up to 25% of elderly men. This disease can cause significant disability in affected patients often necessitating surgical intervention. Various surgical options have been used to treat refractory CMC arthritis. Any successful surgical intervention must address three goals: removal of diseased joint surfaces, reconstruction of ligamentous stabilizers, and preservation of the joint space. In this article we will discuss various interposition arthroplasty options for CMC arthritis of the thumb.

Hypothalamic CRH mRNA levels are differentially modulated by repeated 'binge' cocaine with or without D(1) dopamine receptor blockade

We previously found that there was a rapid stimulatory effect of acute (1 day) 'binge' cocaine on CRH mRNA levels in the rat hypothalamus. In contrast, after 3 days of 'binge' cocaine, there was a modest decrease (12%) in hypothalamic CRH mRNA levels, which after 14 days of 'binge' cocaine was greater (32%) and significantly lower than control values. Also, our previous studies found an elevation of CRH mRNA in the frontal cortex after 3 days of 'binge' cocaine. The present study was designed to investigate the possible role of dopamine receptors in modulating these effects. Administration of 3 days of 'binge' cocaine (3 x 15 mg/kg, i.p.) was preceded by daily injections of either D(1) (SCH23390, 2 mg/kg) or D(2) (sulpiride, 50 mg/kg) dopamine receptor antagonist. Neither SCH23390 nor sulpiride had an effect on basal CRH mRNA levels in the hypothalamus, frontal cortex or amygdala. Small decreases (10-13%) in hypothalamic CRH mRNA levels were found again to be induced by 3 days of repeated 'binge' cocaine. However, this modest decrease was not found in the rats that received D(1) antagonist SCH23390 pretreatment. Pretreatment with D(2) antagonist sulpiride had no effect on this decrease. These findings suggest that the inhibitory effect of repeated 'binge' cocaine on the hypothalamic CRH mRNA expression is absent when there is D(1), but not D(2), dopamine receptor blockade. In the frontal cortex, pretreatment with either SCH23390 or sulpiride did not alter the increases in the CRH mRNA levels induced by repeated 'binge' cocaine. The results suggest that the cocaine-induced modulation of hypothalamic CRH mRNA expression is secondary to changes in the activity of specific components of dopaminergic systems.

Elevation of guinea pig brain preprodynorphin mRNA expression and hypothalamic-pituitary-adrenal axis activity by "binge" pattern cocaine administration

The endogenous opioid system and the hypothalamic-pituitary-adrenal (HPA) axis have been implicated in many of the neurobiological effects of cocaine. Previous studies in our laboratory showed that "binge" pattern cocaine administration increases preprodynorphin (ppDyn) mRNA levels in the caudate putamen and circulating levels of corticosterone in the rat. The present study extended these findings to guinea pigs, a species known to have a kappa opioid receptor profile similar to that of humans. Male guinea pigs were treated with: (a) "binge" pattern cocaine for 7 days (subchronic) (3 x 15 mg/kg/day, hourly, intraperitoneal); (b) "binge" pattern saline for 5 days followed by "binge" pattern cocaine for 2 days (subacute); or (c) "binge" pattern saline for 7 days. Thirty minutes after the final injection, levels of ppDyn mRNA were quantitated in the nucleus accumbens, caudate putamen, frontal cortex, amygdala, hippocampus, and hypothalamus using a solution hybridization RNase protection assay. Regional distribution of ppDyn mRNA levels in the guinea pig brain was similar to that found in rat, with highest levels in the nucleus accumbens and caudate putamen. In the caudate putamen, ppDyn mRNA was significantly increased following either 2 days (38% increase) or 7 days (32% increase) of "binge" pattern cocaine administration as compared to saline-treated controls. No significant changes in ppDyn mRNA levels were found in any other brain region. Both subacute and subchronic "binge" cocaine administration significantly elevated plasma levels of adrenocorticotropin hormone (ACTH) and cortisol. However, the ACTH and cortisol increases were significantly blunted following 7 days of "binge" cocaine administration as compared to 2 days of drug treatment, reflecting the development of HPA tolerance or adaptation to repeated cocaine administration. Thus, the ppDyn mRNA and HPA responses to cocaine in guinea pigs are similar to those observed in rats.

Detection of single nucleotide polymorphisms of the human mu opioid receptor gene by hybridization or single nucleotide extension on custom oligonucleotide gelpad microchips: potential in studies of addiction

The human mu opioid receptor (MOR) plays a central role in mediating the effects of opioids, both endogenous and exogenous. Epidemiological studies have shown that addiction in general, and especially opiate addiction, has a heritable component. Clinical and laboratory studies suggest that the MOR gene may contribute to the heritable component of vulnerability to develop opiate addiction. Naturally occurring single nucleotide polymorphisms (SNPs) have been identified in the MOR gene by conventional methods. Two coding region SNPs, the A118G and C17T substitutions, occur at high allelic frequencies (10.5% and 6.6%, respectively, in our previous studies). These common SNPs cause amino acid changes in the receptor, and may have implications for differences in individual responses to opioids, as well as decreased or increased vulnerability to opiate addiction. The A118G substitution encodes a variant receptor with binding and signal transduction differences in response to beta-endorphin in cellular assays. Recent innovations in microchip technology offer new potential methods for SNP detection. We report here on the development of two separate approaches using custom oligonucleotide gelpad microarrays for detection of these two common SNPs of the MOR gene in human DNA samples. First, PCR-amplified genomic DNA samples were used to produce target sequences, which were labeled with fluorescent dye and hybridized to custom microchips. Oligonucleotides on these reusable microchips were designed to query nucleotide substitutions at positions 17 and 118 of the MOR gene. Thirty-six human DNA samples were assayed both on these custom microchips and by conventional automated gel sequencing, with highly concordant identification of both heterozygous and homozygous substitutions. A second approach was developed for the C17T SNP utilizing single nucleotide extension on custom microchips. These custom gelpad microchips have potential for the rapid and inexpensive detection of specific SNPs for genetic and genomic studies.

Reduced hypothalamic POMC and anterior pituitary CRF1 receptor mRNA levels after acute, but not chronic, daily "binge" intragastric alcohol administration

BACKGROUND

Endogenous corticotropin-releasing factor (CRF), its pituitary CRF1 receptor, and proopiomelanocortin (POMC) may be involved in the hypothalamic-pituitary-adrenal (HPA) responses to alcohol.

METHODS

Alcohol (1.5 g/kg) or water was administered intragastrically to male Fischer rats after the "binge" pattern regimen, that is, three times daily at 1 hr intervals at the beginning of the light cycle. The levels of CRF, CRF1 receptor, and POMC mRNAs in the hypothalamic-pituitary axis were measured after acute (1 day) or chronic (14 days) binge pattern alcohol administration. Plasma levels of ACTH and corticosterone were measured to examine time-dependent alterations of HPA responses.

RESULTS

Plasma ACTH and corticosterone levels were elevated dramatically after 1 day of acute binge pattern alcohol administration. After 14 days of chronic alcohol, however, no elevation in plasma ACTH levels and an attenuated elevation in plasma corticosterone levels were found. CRF mRNA levels in the hypothalamus were not altered after either acute or chronic alcohol administration. CRF1 receptor mRNA levels in the anterior pituitary were decreased significantly after acute administration, with no change after chronic alcohol administration. POMC mRNA levels in the anterior pituitary were not altered by either acute or chronic alcohol administration. In the hypothalamus, POMC mRNA levels were decreased significantly after acute but not chronic binge alcohol administration.

CONCLUSIONS

These results suggest that (1) rats exposed to chronic binge alcohol develop tolerance in HPA activity, as shown by no elevation of ACTH and an attenuated corticosterone response to chronic alcohol after initial dramatic elevations by acute alcohol administration; (2) a concurrent acute decrease in CRF1 receptor mRNA levels in the anterior pituitary is associated with increased HPA activity, and (3) alterations of POMC gene expression in the hypothalamic region may have implications for a molecular understanding of the neuroendocrine response to alcohol.

Hypothalamic-pituitary-adrenal activity and pro-opiomelanocortin mRNA levels in the hypothalamus and pituitary of the rat are differentially modulated by acute intermittent morphine with or without water restriction stress

Acute administration of morphine stimulates the secretion of hypothalamic-pituitary-adrenal (HPA) hormones, ACTH, beta-endorphin and corticosterone in the rat. In this study we investigated the effects of repeated multiple-dose morphine on HPA activity under two different conditions: without or with water restriction stress. Rats received six intermittent injections of morphine (6.25 mg/kg per injection, s.c.) every 2 h and were killed 30 min after the last injection. The results were as follows. (1) Morphine significantly elevated plasma ACTH and corticosterone levels; water restriction also significantly increased ACTH secretion, but with no significant increase of plasma corticosterone levels. In contrast, rats treated with morphine under the water restriction condition failed to show any increases of either ACTH or corticosterone levels. (2) Morphine did not change pro-opiomelanocortin (POMC) mRNA levels in the anterior pituitary; whereas water restriction significantly increased the POMC mRNA levels. The water restriction-induced increases of POMC mRNA in the anterior pituitary were absent in the rats which received morphine. (3) Morphine significantly increased POMC mRNA levels in the hypothalamus; water restriction had no effect. The morphine-induced increases in POMC mRNA in the hypothalamus were absent in the rat under the water restriction condition. These findings, that the effects of morphine on HPA activation or POMC mRNA expression depend on the presence of stress, suggest a counter-regulatory role of opiates on a stress response and opioid gene expression.

Effects of chronic 'Binge' cocaine administration on plasma ACTH and corticosterone levels in mice deficient in DARPP-32

The product of the DARPP-32 gene mediates intracellular signals initiated by the binding of dopamine to its receptors. Cocaine administration leads to increased activation of dopamine receptors, and causes activation of the stress-responsive hypothalamic-pituitary-adrenal (HPA) axis. We determined the effects of chronic 'binge' pattern cocaine on HPA activity in mice containing a targeted disruption of the DARPP-32 gene. Mice received three daily injections of cocaine (15 mg/kg/injection) for 14 days, and were sacrificed 30 min after the last injection. We measured the levels of plasma adrenocorticotropin (ACTH) and corticosterone which reflect HPA activity. In wild-type controls, 'binge' cocaine administration significantly increased plasma ACTH and corticosterone levels. In contrast, DARPP-32-deficient mice failed to show a significant elevation of either plasma ACTH or corticosterone levels following 'binge' cocaine. The results indicate that DARPP-32 plays a role in mediating the stimulatory effects of cocaine on the HPA axis.

Acute intermittent morphine increases preprodynorphin and kappa opioid receptor mRNA levels in the rat brain

We determined the effects of morphine on mRNA levels for the opioid ligands preprodynorphin (PPD) and preproenkephalin (PPE) and the kappa opioid receptor (KOR). Rats received six injections of morphine (6.25 mg/kg/injection) every 2 h, and were sacrificed 30 min later. mRNA levels were measured in brain tissue after removal of the cortex, cerebellum and brainstem. There were increases in PPD and KOR mRNA levels (P<0.05 and P<0.005, respectively), with no alteration of PPE. These alterations in the kappa/dynorphin system may counter morphine-induced effects on the brain.

Acute "binge" cocaine increases mu-opioid receptor mRNA levels in areas of the rat mesolimbic mesocortical dopamine system

Autoradiography studies demonstrated that chronic "binge" cocaine administration increased mu-opioid receptor density in dopaminergically innervated rat brain regions, including the cingulate cortex, the nucleus accumbens, and the basolateral amygdala. The present study investigated the effects of a single day of binge-pattern cocaine administration (3 x 15 mg/kg, intraperitoneally [i.p.] at hourly intervals) on mu-opioid receptor mRNA levels in selected brain regions. Rats were sacrificed 30 min after the third injection and mRNA levels were measured by a quantitative solution hybridization RNase protection assay. Acute binge cocaine administration significantly increased mu-opioid receptor mRNA levels in the frontal cortex, nucleus accumbens, and amygdala, but not in the caudate-putamen, thalamus, hippocampus, and hypothalamus. As has been suggested for other G-protein coupled receptors, the rapid increase of MOR mRNA reported in this study might represent an adaptive response to compensate for a decrease in number of receptors following cocaine-induced opioid peptide release.

Effects of memantine alone and with acute 'binge' cocaine on hypothalamic-pituitary-adrenal activity in the rat

The effects of memantine, a non-competitive NMDA-receptor antagonist used in the management of dementia, and its coadministration with acute 'binge' pattern cocaine on hypothalamic-pituitary-adrenal axis activity were investigated in the rat. Measurements 3 h after injections showed that memantine alone at 20 mg kg(-1) (i.p.), but not 10 mg kg(-1), increased corticotropin-releasing factor (CRF) mRNA levels in the hypothalamus and both adrenocorticotropic hormone and corticosterone levels in the blood, and decreased type I CRF receptor mRNA in the anterior pituitary. Our previous studies have shown that acute 'binge' cocaine increases CRF mRNA levels in the hypothalamus. In this study, pretreatment with memantine (10 and 20 mg kg(-1), i.p.) did not alter the up-regulation of hypothalamic CRF mRNA induced by acute 'binge' cocaine (3 x 15 mg kg(-1), i.p.). Of interest, pretreatment with memantine at 10 mg kg(-1), which alone had no effect on corticosterone levels, caused a greater elevation of corticosterone levels in combination with 'binge' cocaine than acute 'binge' cocaine alone, indicating that memantine does not attenuate 'binge' cocaine-stimulated hypothalamic-pituitary-adrenal activity. These results indicate that both memantine and acute 'binge' cocaine stimulate hypothalamic-pituitary-adrenal activity by activating CRF neurons in the hypothalamus.

Behavioral stereotypies induced by "binge' cocaine administration are independent of drug-induced increases in corticosterone levels

Cocaine administration causes dramatic stereotypic behavior and elevation of circulating corticosterone levels in rodents. The present study tested the possible role of increased corticosterone in mediating stereotypic behavior caused by "binge' pattern cocaine administration. Animals were administered saline or cocaine intraperitoneally for 3 days, with or without pretreatment with a D1 (SCH 23390, 2 mg/kg) or D2 (sulpiride, 50 mg/kg) dopamine receptor antagonist. Three days of cocaine "binges' significantly increased corticosterone levels in vehicle pretreated rats (P < 0.01). Both SCH 23390 and sulpiride pretreatment daily significantly attenuated this increase (P < 0.01). Cocaine administration caused stereotypic behaviors in vehicle pretreatment rats (P < 0.01). These behavioral responses were blocked by the D1 dopamine receptor antagonist SCH 23390, but not by the D2 antagonist sulpiride. These findings reaffirm the dominant role of the D1 receptor in mediating behavioral stereotypy caused by elevations of extracellular dopamine in the synaptic cleft. The fact that the dose of sulpiride used in these studies prevented the elevation of plasma corticosterone caused by cocaine, without blocking the stereotypy caused by cocaine, indicates that this stereotypic behavior does not require drug-induced elevation in circulating levels of corticosterone.

Chronic food restriction and streptozotocin-induced diabetes differentially alter prodynorphin mRNA levels in rat brain regions

It was previously reported that chronic food restriction and streptozotocin-induced diabetes lead to brain region-specific changes in levels of Prodyn-derived peptides. These changes parallel behavioral adaptations that are reversed by opioid antagonists. In the present study, effects of food restriction and diabetes on Prodyn gene expression were measured in rat brain regions using a quantitative solution hybridization mRNA assay. Picogram amounts of Prodyn mRNA were determined in extracts of five brain regions. The highest density of Prodyn mRNA was observed in extracts of nucleus accumbens (4.68 pg/microg total RNA), bed nucleus of the stria terminalis (4.18 pg/microg), and in caudate nucleus (3.51 pg/microg). Lower levels were observed in the lateral hypothalamus (1.87 pg/microg) and central nucleus of the amygdala (1.22 pg/microg). Food restriction and diabetes both markedly increased the levels of Prodyn mRNA in the central amygdala (163% and 93%, respectively). Levels in the lateral hypothalamus were also increased (35% and 29%, respectively), though only the food-restriction effect was statistically significant. Neither treatment altered prodynorphin mRNA levels in the caudate nucleus, nucleus accumbens or bed nucleus of the stria terminalis. These results suggest that dynorphin neurons in central amygdala and lateral hypothalamus may be involved in behavioral or physiological adaptations to sustained metabolic need.

Quantitation of dopamine transporter mRNA in the rat brain: mapping, effects of "binge" cocaine administration and withdrawal

Dopamine transporter (DAT) mRNA from selected brain regions of individual male Fischer rats was quantitated utilizing a sensitive solution hybridization assay in which the levels of RNase-protected 32P-labeled mRNA:cRNA hybrids were measured. DAT mRNA was detected in whole brain regions known to contain abundant DAT mRNA (mean picogram of DAT mRNA/microgram of total RNA +/- SEM): substantia nigra, 7.17 +/- 0.47; ventral tegmentum, 4.71 +/- 0.38. In regions known to contain low levels of DAT mRNA, these levels were detected: central grey, 0.39 +/- 0.06; hypothalamus, 0.14 +/- 0.03. In addition, DAT mRNA was detected in areas where it had not previously been identified: amygdala, 0.19 +/- 0.03; caudate-putamen, 0.15 +/- 0.03; nucleus accumbens, 0.13 +/- 0.01; pons/medulla, 0.12 +/- 0.02; globus pallidus, 0.09 +/- 0.04; pituitary 0.07 +/- 0.01; frontal cortex, 0.05 +/- 0.01. No DAT mRNA was detected in 150 micrograms of rat liver RNA. As cocaine binds to and inhibits the activity of the dopamine transporter, we sought to determine if there were differences in dopamine transporter mRNA levels between saline- and cocaine-injected rats or rats withdrawn from a chronic "binge" pattern (15 mg/kg per dose i.p.; three doses at 1 h intervals each day) cocaine injection. Using trichloroacetic acid precipitation of mRNA:cRNA hybrids from RNA extracted from whole brain regions, we found no significant differences in the substantia nigra or the ventral tegmentum following subacute (3 days) binge, chronic (14 days) binge or 10 days withdrawal from a chronic binge pattern cocaine or saline administration.

Prodynorphin, proenkephalin and kappa opioid receptor mRNA responses to acute "binge" cocaine

Previous studies showed that preprodynorphin (ppDyn) mRNA increases in caudate-putamen while kappa opioid receptor (KOR) mRNA decreases in substantia nigra after 3 and 14 days "binge" cocaine. To further characterize opioid mRNA responses, rats were administered: saline; 1 day cocaine followed by 1 day saline; 1 day cocaine; or 2 days cocaine. ppDyn mRNA in caudate-putamen increased in both groups receiving cocaine on the final day compared to groups receiving saline. Preproenkephalin (ppEnk) mRNA in caudate-putamen increased, and KOR mRNA in substantia nigra decreased, after 2 days of cocaine. Thus ppDyn mRNA is elevated acutely by cocaine, while ppEnk and KOR mRNAs show a significant response only on the second day of "binge" cocaine.

Guinea pig preprodynorphin mRNA: primary structure and regional quantitation in the brain

We isolated and sequenced genomic and cDNA clones of the guinea pig preprodynorphin (ppDyn) mRNA. The sequence of ppDyn mRNA was deduced from a combination of genomic and cDNA clones: The primary structure of two coding exons was derived from a genomic clone and 5' and 3' untranslated sequences were obtained using rapid amplification of cDNA ends (RACE). The predicted mRNA of 2,350 nucleotides coincides well with the size of transcripts in Northern blot analyses of RNA from different brain regions. The deduced amino acid sequence of guinea pig ppDyn shares 70%, 68%, and 61% identity to porcine, human, and rat ppDyn, respectively. The 5' untranslated sequences of guinea pig hippocampal and adrenal ppDyn mRNA are identical; both contain sequences of exon I and, like porcine mRNA, lack an exon (exon II) present in human and rat mRNA. Quantitative solution hybridization RNase protection analysis of total RNA from selected guinea pig brain regions was performed. The nucleus accumbens was found to have the greatest abundance of ppDyn mRNA, followed by caudate putamen, hippocampus, hypothalamus, amygdala, frontal cortex, olfactory bulb, and pons/medulla.

Steady-state methadone in rats does not change mRNA levels of corticotropin-releasing factor, its pituitary receptor or proopiomelanocortin

Male Fischer rats received either methadone (a long-acting opioid agonist, 10 mg/kg/day) or saline (24 microliters/day) subcutaneously by osmotic minipumps for 7 days. Chronic steady-state methadone administration did not alter (a) corticotropin-releasing factor (CRF) mRNA in the hypothalamus, (b) proopiomelanocortin (POMC) and CRF type 1 receptor (CRF-R1) mRNAs in the anterior lobe and neurointermediate/posterior lobe of the pituitary, or (c) circulating levels of corticosterone. No change was found in levels of either POMC mRNA in the hypothalamus and amygdala, or CRF mRNA in the frontal cortex, olfactory bulb and amygdala. These results demonstrate that neither the activity of the hypothalamic-pituitary-adrenal axis, nor the beta-endorphin and CRF systems in the brain, are altered by steady-state occupancy of opioid receptors with the long-acting opioid agonist methadone.

Corticotropin-releasing factor and type 1 corticotropin-releasing factor receptor messenger RNAs in rat brain and pituitary during "binge"-pattern cocaine administration and chronic withdrawal

Endogenous central corticotropin-releasing factor (CRF) may be involved in the neuroendocrine and behavioral responses to cocaine. In the present study, levels of CRF mRNA were measured in the hypothalamus and in several extrahypothalamic brain regions after different regimens of "binge"-pattern cocaine administration. Male Fischer rats were injected with saline or cocaine (15 mg/kg, 1 hr x 3/day) at the beginning of the light cycle, to approximate the manner in which cocaine is often abused by humans, both in terms of temporal pattern and in relation to circadian rhythm. Cocaine administered in this binge regimen produced time-dependent alterations of CRF mRNA levels in the hypothalamus. There was a significant increase in CRF mRNA levels on day 1, which returned to base-line levels on day 2, with elevated plasma corticosterone levels on both days. CRF receptor type 1 and prooplomeianocortin mRNA levels in the anterior lobe of the pituitary were not significantly altered after acute cocaine injections on day 1 or day 2. On day 14 of chronic binge-pattern cocaine administration, decreased hypothalamic CRF mRNA levels and an attenuated elevation in plasma corticosterone levels were found. After 10 days of withdrawal from 14-day binge cocaine, CRF mRNA returned to basal levels. CRF mRNA levels in the amygdala were also significantly increased on day 1 and returned to basal values on day 2. Chronic (14-day) binge cocaine administration did not alter CRF mRNA levels in the amygdala. These results suggest that the attenuated response in the hypothalamic-pituitary-adrenal axis to chronic binge cocaine administration is coupled to the cocaine-induced decreases in CRF gene expression in the hypothalamus and that activation of CRF gene expression in extrahypothalamic regions may have implications for a molecular understanding of the behavioral responses to cocaine.

Dopamine antagonist and "binge' cocaine effects on rat opioid and dopamine transporter mRNAs

The modulation by selective dopamine receptor antagonists of the effects of "binge' cocaine (3 x 15 mg kg-1 day-1, i.p., for 3 days after 11 days of adaptation to saline injections) on preproenkephalin, preprodynorphin, kappa opioid receptor and dopamine transporter mRNAs was determined. Administration of cocaine was preceded by daily single injections of a D1 (SCH 23390; 2 mg kg-1) or the D2 (sulpiride; 50 mg kg-1) dopamine receptor antagonist. The D1, and not the D2, antagonist blocked cocaine-induced preprodynorphine and preproenkephalin increases in the caudate-putamen. Sulpiride alone, and sulpiride plus cocaine, increased preproenkephalin mRNA. Dopamine transporter mRNA levels showed a cocaine treatment-antagonist interaction. These data indicate that this administration paradigm elevates both preprodynorphin and preproenkephalin mRNAs by a D1-dependent mechanism not requiring D2 activation.

The in vitro effects of 6-methoxy-2-naphthylacetic acid, the active metabolite of nabumetone, on rat gastric mucosal eicosanoid synthesis and metabolism

Nabumetone is a neutral non-steroidal anti-inflammatory drug with a low propensity to cause gastrointestinal (GI) damage. Previous studies, in vivo, have shown that the drug has weak effects on gastric mucosal cyclooxygenase activity, which may help to explain its favourable GI profile. The present study set out to determine whether the observed effects of nabumetone on cyclooxygenase, in vivo, parallel those of its active metabolite, 6-methoxy-2-naphthylacetic acid (6MNA), in vitro. We have also studied nabumetone and 6MNA on two other systems, namely 15-prostaglandin dehydrogenase (15-PGDH) and 5-lipoxy-genase (5-LO), which when inhibited may confer mucosal protection. The results showed that 6MNA had variable effects on cyclooxygenase activity, depending on the concentration and was less potent and less effective than indomethacin. Cyclooxygenase activity was not inhibited by the reversible inhibitor, aminopyrine, but at low concentrations stimulation was observed. Sulphasalazine inhibited 15-PGDH in a concentration-dependent manner whereas 6MNA inhibited it only at high concentrations. Nabumetone was devoid of activity. Basal 5-LO activity was attenuated by phenidone and unaltered by 6MNA but increased by nabumetone at the highest concentration. In the presence of arachidonic acid, to raise 5-LO activity, nabumetone, 6MNA, BW755C and phenidone apparently inhibited this activity. However, it was possible that both nabumetone and 6MNA inhibited a prostanoid-mediated stimulatory effect on 5-LO rather than effecting enzyme inhibition per se. Nabumetone's favourable GI profile may, therefore, relate to 6MNA having weak effects on mucosal cyclooxygenase and is unlikely to involve inhibition of prostanoid metabolism or 5-LO.

Regulation of kappa opioid receptor mRNA in the rat brain by "binge' pattern cocaine administration and correlation with preprodynorphin mRNA

We previously reported that 'binge' pattern administration of cocaine elevates preprodynorphin (ppDyn) mRNA in the caudate-putamen of rats. The present study confirms this finding. In addition, we report here that "binge' pattern administration of cocaine leads to a significant decrease in the mean level of kappa opioid receptor (KOR) mRNA in the substantia nigra, with no significant change in the mean level of KOR mRNA in the caudate-putamen. The decrease in KOR mRNA in the substantia nigra after 3 day or 14 day 'binge' administration of cocaine was comparable to the increase in ppDyn mRNA in the caudate-putamen. While there was no significant change in the mean levels of KOR mRNA in the caudate-putamen following cocaine administration, there was a positive within animal correlation between the levels of ppDyn mRNA and KOR mRNA in the caudate-putamen, both in animals administered saline and in animals receiving 'binge' cocaine for 14 days. Finally, mean levels of ppDyn or KOR mRNA in cocaine treated rats were not different from saline treated controls following a 10 day withdrawal from 14 days of 'binge' cocaine administration. The results provide evidence of regulation of KOR mRNA by cocaine in the substantia nigra.

Modulation of CRF-R1 mRNA in rat anterior pituitary by dexamethasone: correlation with POMC mRNA

Glucocorticoids have been shown to decrease CRF receptor binding in the anterior pituitary. To determine whether glucocorticoids or CRF peptide modulate CRF-R1 gene expression, CRF-R1 mRNA levels in rat pituitary and brain were measured after administration of a synthetic glucocorticoid, dexamethasone (DEX) or rat/human CRF (r/hCRF), using a sensitive solution hybridization RNase protection assay. DEX (400 micrograms/day) or r/hCRF (100 micrograms/kg/day) was administered twice daily for 5 days to male rats. DEX treatment caused a significant decrease in CRF-R1 mRNA levels in the anterior pituitary. Also, a significant positive correlation was found between CRF-R1 and POMC mRNA levels in the anterior pituitary of the individual animals: levels of both mRNAs were reduced by DEX. However, r/hCRF treatment had no significant effect on CRF-R1 mRNA levels in the anterior pituitary. In extrahypothalamic brain regions, mRNA levels of CRF-R1 did not change following either DEX or r/hCRF administration. Our data suggest that in addition to POMC and CRF genes, CRF-R1 gene may also be subject to negative feedback control by glucocorticoids.

Effect of 6-Methoxy-2-Naphthylacetic Acid (6MNA), the Active Metabolite of Nabumetone, on the Glycosaminoglycan Synthesis of Canine Articular Cartilage In Vitro : Comparison with Other Nonsteroidal Anti-Inflammatory Drugs

6-methoxy-2-naphthylacetic acid (6MNA), the active metabolite of nabumetone, a novel nonacidic NSAID, has been studied in an in vitro culture system to determine its effects on glycosaminoglycan synthesis of normal and osteoarthritic canine articular cartilage. The effects were contrasted with those of several other NSAIDs. Dexamethasone potently inhibited synthesis and was used as a positive control in these studies. To reduce the influence of protein binding with these drugs, experiments were performed both in the presence and in the absence of serum in the culture medium. At and above concentrations achieved in the plasma of nabumetone-treated patients, 6MNA did not inhibit glycosaminoglycan synthesis of normal or osteoarthritic cartilage. In contrast, some other NSAIDs had the propensity to significantly suppress chondrocyte synthetic activity.

Nabumetone, an effective anti-inflammatory agent, lacks gastrointestinal irritancy in the rat when dosed orally for one month: comparison with tiaprofenic acid and etodolac

OBJECTIVE

To determine the effects of nabumetone, compared with tiaprofenic acid and etodolac, on anti-inflammatory efficacy and gastrointestinal irritancy in the rat when dosed orally for one month at a high anti-inflammatory dose.

METHODS

Carrageenan paw edema was used as a model of inflammation. Gastrointestinal mucosal integrity was assessed by concurrently measuring ulcer formation. mucosal and tissue prostanoid production and plasma haptoglobin. Haemoglobin, present in the cecal contents, was used as a measure of blood loss.

RESULTS

Nabumetone, tiaprofenic acid and etodolac inhibited inflammation. Etodolac induced marked gastrointestinal damage and blood loss whereas tiaprofenic acid caused only gastric damage. Nabumetone was found not to alter mucosal integrity.

CONCLUSION

Nabumetone proved to be an effective anti-inflammatory agent that was devoid of gastrointestinal irritancy.

'Binge' cocaine administration induces a sustained increase of prodynorphin mRNA in rat caudate-putamen

Other workers have established that cocaine injections increase the levels of dynorphin peptides in the caudate putamen and substantia nigra of the rat brain. Using a quantitative solution hybridization protection assay for mRNA, we detected a significant increase in the concentration of prodynorphin mRNA in caudate putamen extracts of rats injected with cocaine following a 'binge' administration pattern designed to mimic human cocaine abuse. Increased prodynorphin mRNA was observed at the earliest time-point studied (50 h) and the lowest dose (10 mg/kg/day) of cocaine tested and persisted through the 14 day period studied. No prodynorphin mRNA was detected in the substantia nigra.

c-myc is an erythropoietin early response gene in normal erythroid cells: evidence for a protein kinase C-mediated signal

The proto-oncogene c-myc has been identified as an early response gene for erythropoietin (Epo) in transformed murine erythroleukemia cells. Epo activation of c-myc in these cells requires protein kinase C. We now show the fidelity of this signaling pathway in normal erythroid cells isolated from the spleens of phenylhydrazine-treated mice. Mouse spleen cells rich in erythroid progenitors were washed free of endogenous Epo and then incubated in the absence of Epo. Subsequent addition of Epo for 1 hour led to a dramatic elevation of c-myc transcript. Addition of the protein synthesis inhibitor cycloheximide did not prevent the c-myc response, thus identifying c-myc as an Epo early response gene in normal cells. We used this c-myc response as a reporter for signals initiated by the Epo receptor. Using a series of inhibitors with known specificities and established rank-orders of potency for different kinases, we determined that the c-myc response to Epo was blocked with the following rank order: staurosporine much greater than H7 greater than sangivamycin greater than H8. This sequence is identical to that obtained using transformed cells and is diagnostic of a protein kinase C-dependent signal. Because direct activation of protein kinase by phorbol esters does not induce terminal differentiation of normal cells, the pathway to c-myc established by these studies must represent one part of a signal transduction mechanism.

Erythropoietin induces cytosolic protein phosphorylation and dephosphorylation in erythroid cells

Erythropoietin, the prime regulator of red blood cell growth and differentiation, causes rapid changes in the phosphorylation of several integral plasma membrane proteins (Choi, H-S., Wojchowski, D. M., and Sytkowski, A. J. (1987) J. Biol. Chem. 262, 2933-2936; Choi, H-S., Bailey, S. C., Donahue, K. A., Vanasse, G. J., and Sytkowski, A. J. (1990) J. Biol. Chem. 265, 4143-4148). In the present study we have demonstrated that erythropoietin's signal is transduced rapidly to the cytosol resulting in specific phosphorylation/dephosphorylation events. Erythropoietin treatment of Rauscher murine erythroleukemia cells previously labeled with [32P]orthophosphate results in a rapid increase in phosphorylation of two cytosolic proteins, designated pp96 and pp80, and a decrease in phosphorylation of another protein, designated pp90. The relative molecular mass and pI of pp80 are virtually identical to those reported for the protein kinase C substrate p80, or "MARCKS protein." Treatment of the cells with 12-O-tetradecanoylphorbol-13-acetate also increases pp80 but not pp96 phosphorylation, suggesting that erythropoietin triggers a protein kinase C-dependent pathway to pp80 and a protein kinase C-independent pathway to pp96. The effect of erythropoietin on pp96 phosphorylation was also shown in nontransformed erythroid cells isolated from the spleens of phenylhydrazine-treated mice. In contrast, almost no 32P labeling of pp80 or pp90 was detected, and pp80 and pp90 protein were nearly absent from these normal cells. These differences in expression and phosphorylation of erythropoietin-sensitive phosphoproteins may be related to the growth factor independence or dependence of the erythroid cells.

Evidence that a G-protein transduces signals initiated by the protein-tyrosine kinase v-Fps

The protein-tyrosine kinase (PTK) v-Fps induces protein kinase C (PKC)-dependent expression of the transformation-related 9E3 gene in chicken embryo fibroblasts (Spangler, R., Joseph, C., Qureshi, S.A., Berg, K., and Foster, D.A. (1989) Proc. Natl. Acad. Sci. U.S.A. 86, 7017-7021). We present evidence here that a GTP-binding protein (G-protein) is a component of this PKC-dependent signaling pathway. 1) A GTP analogue that stimulates G-protein-mediated signals induced 9E3 gene expression. 2) A GDP analogue that inhibits signaling through G-proteins inhibited expression of 9E3 and phosphorylation of a 67-kDa PKC substrate induced by v-Fps. The GDP analogue had no effect on phosphorylation of the PKC substrate or the expression of 9E3 induced by direct activation of PKC with phorbol ester. 3) Increased v-Fps PTK activity led to increased GTP binding to a 50-kDa protein. The molecular weight of this GTP-binding protein is consistent with the molecular weight of alpha-subunits of G-proteins of the heterotrimeric class. The data suggest that a G-protein functions upstream from PKC in a signaling pathway that connects v-Fps PTK activity to increased 9E3 gene expression.

Erythropoietin activates the receptor in both Rauscher and Friend murine erythroleukemia cells

Alterations in the expression of two proto-oncogenes, c-myb and c-myc, have been implicated in the differentiation of transformed erythroid cells induced by chemical inducers, such as dimethyl sulfoxide (Me2SO). In the present study, we compared the expression of c-myb and c-myc during erythropoietin (Epo) and Me2SO induction of Rauscher erythroleukemia cells, which differentiate in response to both inducers, and Friend erythroleukemia cells, in which Epo-induced differentiation is blocked. Our results demonstrate that Epo induces specific changes in expression of c-myb and c-myc in both Rauscher and Friend cells. Epo increases c-myc transcript, in contrast to a decreased caused Me2SO, indicating that the biphasic mode of c-myc regulation seen with Me2SO is not required for erythropoiesis. The Epo-induced changes in c-myb and c-myc do not require new protein synthesis, thus identifying these proto-oncogenes as early response genes for Epo. Both cell types also exhibit rapid changes in membrane protein phosphorylation in response to Epo. Since the signal pathway from Epo receptor activation to the nucleus appears equally functional in both Rauscher and Friend cells, the data suggest that the inability of Friend cells to differentiate in response to Epo is due to a block at a later step in the induction process.

Cholera toxin induces expression of the immediate-early response gene JE via a cyclic AMP-independent signaling pathway

Cholera toxin (CT) activates expression of two immediate-early response genes (JE and TIS10) in quiescent BALB/c 3T3 cells. Increases in cyclic AMP (cAMP) levels in response to CT are likely responsible for the induction of TIS10 gene expression, since treatment with 8-Br-cAMP and increasing the intracellular levels of cAMP by treatment with forskolin induce TIS10 gene expression. In contrast, neither forskolin nor 8-Br-cAMP induces JE gene expression. 3-Isobutyl-1-methylxanthine, which stabilizes intracellular cAMP, potentiates CT-induced TIS10 gene expression but has no effect on CT-induced JE gene expression. Thus, induction of JE by CT is independent of the cAMP produced in response to CT. Induction of JE by CT does not require protein kinase C (PKC), since depleting cells of PKC activity has no effect on the induction of JE by CT. CT-induced expression of JE can be distinguished from CT-induced TIS10 gene expression by using protein kinase inhibitors and inhibitors of arachidonic acid metabolism, further suggesting distinct signaling pathways for CT-induced JE and TIS10 gene expression. Thus, induction of JE gene expression by CT results from the activation of an intracellular signaling pathway that is independent of cAMP production. This pathway is independent of PKC activity and uniquely sensitive to inhibitors of protein kinases and arachidonic acid metabolism.