Detection of prions from spiked and free-ranging carnivore feces

Chronic wasting disease (CWD) is a highly contagious, fatal neurodegenerative disease caused by infectious prions (PrPCWD) affecting wild and captive cervids. Although experimental feeding studies have demonstrated prions in feces of crows (Corvus brachyrhynchos), coyotes (Canis latrans), and cougars (Puma concolor), the role of scavengers and predators in CWD epidemiology remains poorly understood. Here we applied the real-time quaking-induced conversion (RT-QuIC) assay to detect PrPCWD in feces from cervid consumers, to advance surveillance approaches, which could be used to improve disease research and adaptive management of CWD. We assessed recovery and detection of PrPCWD by experimental spiking of PrPCWD into carnivore feces from 9 species sourced from CWD-free populations or captive facilities. We then applied this technique to detect PrPCWD from feces of predators and scavengers in free-ranging populations. Our results demonstrate that spiked PrPCWD is detectable from feces of free-ranging mammalian and avian carnivores using RT-QuIC. Results show that PrPCWD acquired in natural settings is detectable in feces from free-ranging carnivores, and that PrPCWD rates of detection in carnivore feces reflect relative prevalence estimates observed in the corresponding cervid populations. This study adapts an important diagnostic tool for CWD, allowing investigation of the epidemiology of CWD at the community-level.

Leptin activation of dorsal raphe neurons inhibits feeding behavior

Leptin is a homeostatic regulatory element that signals the presence of energy stores -in the form of adipocytes-which ultimately reduces food intake and increases energy expenditure. Similarly, serotonin (5-HT), a signaling molecule found in both the central and peripheral nervous systems, also regulates food intake. Here we use a combination of pharmacological manipulations, optogenetics, retrograde tracing, and in situ hybridization, combined with behavioral endpoints to physiologically and anatomically identify a novel leptin-mediated pathway between 5-HT neurons in the dorsal raphe nucleus (DRN) and hypothalamic arcuate nucleus (ARC) that controls food intake. In this study, we show that microinjecting leptin directly into the DRN reduces food intake in male Sprague-Dawley rats. This effect is mediated by leptin-receptor expressing neurons in the DRN as selective optogenetic activation of these neurons at either their ARC terminals or DRN cell bodies also reduces food intake. Anatomically, we identified a unique population of serotonergic raphe neurons expressing leptin receptors that send projections to the ARC. Finally, by utilizing in vivo microdialysis and high-performance liquid chromatography, we show that leptin administration to the DRN increases 5-HT efflux into the ARC. Overall, this study identifies a novel circuit for leptin-mediated control of food intake through a DRN-ARC pathway, utilizing 5-HT as a mechanism to control feeding behavior. Characterization of this new pathway creates opportunities for understanding how the brain controls eating behavior, as well as opens alternative routes for the treatment of eating disorders.

Significance

Leptin and serotonin both play a vital role in the regulation of food intake, yet there is still uncertainty in how these two molecules interact to control appetite. The purpose of this study is to further understand the anatomical and functional connections between leptin receptor expressing neurons in the dorsal raphe nucleus, the main source of serotonin, and the arcuate nucleus of the hypothalamus, and how serotonin plays a role in this pathway to reduce food intake. Insight gained from this study will contribute to a more thorough understanding of the networks that regulate food intake, and open alternative avenues for the development of treatments for obesity and eating disorders.

Comparative sensitivity of aquatic invertebrate and vertebrate species to wastewater from an operational coal mine in central Queensland, Australia

Coal excavation and refinement processes generate substantial volumes of contaminated effluent that may be detrimental to aquatic ecosystems. As such, understanding the impacts of coal mine water releases on aquatic animals and ecosystems is essential for effectively managing and protecting neighboring environments. Such information will ultimately be applied towards developing ongoing monitoring strategies that are protective of native wildlife. Despite intensive mining operations in Australia, few studies have documented toxicity associated with coal mine wastewater (CMW) on native species. To address existing knowledge gaps, we investigated acute toxicity (48-96h) using eight native invertebrate species and sub-chronic effects (2 week) using three vertebrate species following exposure to wastewater from two dams (CMW1 and CMW2) located at an open-cut coal mine licensed to discharge into the Fitzroy catchment (Queensland, Australia). Wastewater from these sites is characterized by elevated conductivity, pH, sulfates as well as relatively high total and dissolved metal(loid)s (including As, Al, B, Cu, Mn, Ni, Se and Zn). Acute exposures revealed cladocerans (Daphnia carinata) and planarians (Dugesia sp.) to be the most sensitive species, exhibiting significant mortality after 48 and 96h exposure to CMW2, respectively. Neither wastewater was found to elicit acute toxicity in vertebrates, but a range of sub-lethal morphological effects were observed following the sub-chronic exposures. The overall response pattern was characterized by decreased condition factor and hepatosomatic index in the fish Hypseleotris compressa and Pseudomugil signifier, and in Limnodynastes peronii tadpoles. Tadpoles were generally more sensitive compared to the two fish species. Differences in responses were observed amongst CMW1 and CMW2, which likely relates to differences in physico-chemical properties between sites. Our results have identified several candidate vertebrate and invertebrate species that show promise for ongoing monitoring of water quality and toxicity risk in Central Queensland, Australia.

Effects of coal mine wastewater on locomotor and non-locomotor activities of empire gudgeons (Hypseleotris compressa)

Coal mining represents an important industry in many countries, but concerns exist about the possible adverse effects of minewater releases on aquatic animals and ecosystems. Coal mining generates large volumes of complex wastewater, which often contains high concentrations of dissolved solids, suspended solids, metals, hydrocarbons, salts and other compounds. Traditional toxicological testing has generally involved the assessment of acute toxicity or chronic toxicity with longer-term tests, and while such tests provide useful information, they are poorly suited to ongoing monitoring or rapid assessment following accidental discharge events. As such, there is considerable interest in developing rapid and sensitive approaches to environmental monitoring, and particularly involving the assessment of sub-lethal behavioural responses in locally relevant aquatic species. We therefore investigated behavioural responses of a native Australian fish to coal mine wastewater, to evaluate its potential use for evaluating sub-lethal effects associated with wastewater releases on freshwater ecosystems. Empire gudgeons (Hypseleotris compressa) were exposed to wastewater from two dams located at an open cut coal mine in Central Queensland, Australia and activity levels were monitored using the Multispecies Freshwater Biomonitor® (LimCo International GmbH). A general decrease in locomotor activity (i.e., low frequency movement) and increase in non-locomotor activity (i.e., high frequency movement including ventilation and small fin movement) was observed in exposed fish compared to those in control water. Altered activity levels were observable within the first hour of exposure and persisted throughout the 15-d experiment. Results demonstrate the potential for using behavioural endpoints as tools for monitoring wastewater discharges using native fish species, but more research is necessary to identify responsible compounds and response thresholds, and to understand the relevance of the observed effects for populations in natural receiving environments.

Marine debris is selected as nesting material by the brown booby (Sula leucogaster) within the Swain Reefs, Great Barrier Reef, Australia

Many seabirds are impacted by marine debris through its presence in foraging and nesting areas. To determine the extent of this problem, marine debris use in nest material of the brown booby (Sula leucogaster) in the Great Barrier Reef, Australia, was investigated. Nine cays were examined using beach and nest surveys. On average, four marine debris items were found per nest (n=96) with 58.3% of surveyed nests containing marine debris. The source of marine debris in nests and transects were primarily oceanic. Hard plastic items dominated both nest (56.8%) and surveyed beaches (72.8%), however only two item types were significantly correlated between these surveys. Nest surveys indicated higher levels of black and green items compared to beach transects. This selectivity for colours and items suggest these nests are not good indicators of environmental loads. This is the first study to examine S. leucogaster nests for marine debris in this location.

Gene therapy for trigeminal pain in mice

The aim of this study was to test the efficacy of a single direct injection of viral vector encoding for encephalin to induce a widespread expression of the transgene and potential analgesic effect in trigeminal behavioral pain models in mice. After direct injection of HSV-1 based vectors encoding for human preproenkephalin (SHPE) or the lacZ reporter gene (SHZ.1, control virus) into the trigeminal ganglia in mice, we performed an orofacial formalin test and assessed the cumulative nociceptive behavior at different time points after injection of the viral vectors. We observed an analgesic effect on nociceptive behavior that lasted up to 8 weeks after a single injection of SHPE into the trigeminal ganglia. Control virus injected animals showed nociceptive behavior similar to naïve mice. The analgesic effect of SHPE injection was reversed/attenuated by subcutaneous naloxone injections, a μ-opioid receptor antagonist. SHPE injected mice also showed normalization in withdrawal latencies upon thermal noxious stimulation of inflamed ears after subdermal complete Freund’s adjuvans injection indicating widespread expression of the transgene. Quantitative immunohistochemistry of trigeminal ganglia showed expression of human preproenkephalin after SHPE injection.

Direct injection of viral vectors proved to be useful for exploring the distinct pathophysiology of the trigeminal system and could also be an interesting addition to the pain therapists’ armamentarium.

Ingestion of marine debris plastic by the wedge-tailed shearwater Ardenna pacifica in the Great Barrier Reef, Australia

We present the first evidence of ingestion of plastic by seabirds from the southern Great Barrier Reef (GBR), Australia. The occurrence of marine debris ingestion in the wedge-tailed shearwater, Ardenna pacifica, on Heron Island was the focus of this preliminary research. Our findings indicate that 21% of surveyed chicks are fed plastic fragments by their parents, having ingested 3.2 fragments on average. The most common colours of ingested plastic fragments were off/white (37.5%) and green (31.3%). Ingested fragments had a mean size of 10.17±4.55 mm and a mean weight of 0.056±0.051 g. Our results indicate that further research is critical to understanding the extent of ingestion, colour preferences, and what impacts ingestion may have on these and other seabird populations in the GBR.

Decrease in the expression of N-methyl-D-aspartate receptors in the nucleus tractus solitarii induces antinociception and increases blood pressure

N-methyl-D-aspartate receptors (NMDAR) have a role in cardiovascular control at the nucleus tractus solitarii (NTS), eliciting increases or decreases in blood pressure (BP), depending on the area injected with the agonists. In spite of the association between cardiovascular control and pain modulation, the effects of manipulating NMDAR in pain responses have never been evaluated. In this study, we decreased the expression of NMDAR in the NTS using gene transfer to target receptor subunits and evaluate long-term effects. Seven days after the injection of lentiviral vectors containing the NR1a subunit cDNA of NMDAR, in antisense orientation, into the intermediate NTS of Wistar rats, BP was measured, and the formalin test of nociception was performed. The antisense vector induced a decrease of NR1 expression in the NTS and elicited BP rises and hypoalgesia. Antisense vectors inhibited formalin-evoked c-Fos expression in the spinal cord, indicating decreased nociceptive activity of spinal neurons. Using a time-course approach, we verified that the onset of both the increases in BP and the hypoalgesia was at 4 days after vector injection into the NTS. The injection of NMDA into the NTS reversed the effects of antisense vectors in pain behavioral responses and spinal neuronal activation and decreased BP and heart rate. The present study shows that the NR1 subunit of the NMDAR at the NTS is critical in the regulation of tonic cardiovascular and nociceptive control and shows an involvement of the nucleus in the modulation of sustained pain.

Ecological impacts of tributyltin on estuarine communities in the Hastings River, NSW Australia

Oyster (Saccostrea commercialis) biomonitoring, assessment of oyster and gastropod (Bembicium auratum) abundance, and gastropod imposex were used to measure the significance of tributyltin (TBT) contamination in an intertidal mangrove forest. We studied the bioavailable levels of TBT in oysters approximately 1 km downstream and 2 km upstream from a TBT waste disposal site. We found observable declines in the abundance of oysters and gastropods correlated with the bioavailable TBT and these findings were confirmed by mapping oyster beds. Oyster cover near the disposal site ranged from 0% to 5% while downstream and upstream populations ranged in cover from 25-50% to 5-25%, respectively. Similarly, gastropod abundances at the disposal site were only 7% of the downstream population and 17% of the upstream population. Imposex was present in 90% of female B. auratum from populations near the disposal site but this effect declined more sharply than the population level effects.

Lentivirus-mediated downregulation of hypothalamic insulin receptor expression

Regulation of feeding behavior and energy balance are among the central effects of insulin. For example, intracerebroventricular administration of insulin decreases food intake and body weight, whereas antisense oligodeoxynucleotide downregulation of insulin receptors (IRs) produces hyperphagia. To further examine the role of IRs in the central actions of insulin, we designed an IR antisense lentiviral vector (LV-IRAS) and injected this vector into the third ventricle to selectively decrease IR expression in the rat hypothalamus. Three weeks after LV-IRAS administration, the expression of IRs in the hypothalamus was significantly decreased, whereas no changes were observed in hippocampal IR levels. LV-IRAS administration decreased insulin-stimulated phosphorylation of hypothalamic IRs and translocation of the insulin-sensitive glucose transporter GLUT4 in the hypothalamus; no changes in IR signaling were observed in the hippocampus of LV-IRAS-treated rats. Lentivirus-mediated downregulation of IR expression and signaling produced significant increases in body weight, as well as increases in fat mass that were selective for the subcutaneous compartment. Conversely, lean muscle mass and water mass were not affected in LV-IRAS-treated rats compared to rats treated with control virus. Changes in peripheral adiposity were associated with increases in basal hypothalamic leptin signaling in the absence of changes in leptin receptor expression in LV-IRAS rats. Collectively, these data illustrate the important functional relationships between hypothalamic insulin and leptin signaling in the regulation of body composition and provide insight into the mechanisms through which decreases in IR expression and signaling dysregulates leptin activity, thereby promoting increases in peripheral adiposity.

Decrease in inflammatory hyperalgesia by herpes vector-mediated knockdown of Nav1.7 sodium channels in primary afferents

Induction of peripheral inflammation increases the expression of the Nav1.7 sodium channel in sensory neurons, potentially increasing their excitability. Peripheral inflammation also produces hyperalgesia in humans and an increase in nociceptive responsiveness in animals. To test the relationship between these two phenomena we applied a recombinant herpes simplex-based vector to the hindpaw skin of mice, which encoded both green fluorescent protein (GFP) as well as an antisense sequence to the Nav1.7 gene. The hindpaw was subsequently injected with complete Freund's adjuvant to induce robust inflammation. Application of the vector, but not a control vector encoding only GFP, prevented an increase in Nav1.7 expression in GFP-positive neurons and prevented development of hyperalgesia in both C and Adelta thermonociceptive tests. These results provide clear evidence of the involvement of an increased expression of the Nav1.7 channel in nociceptive neurons in the development of inflammatory hyperalgesia.

Genetic therapy for pain management

Two approaches to genetic therapy for the management of chronic pain have recently been investigated in animal models of pain. First, transgene-mediated delivery of antinociceptive molecules to the cerebrospinal fluid has been performed with engineered cell lines transplanted to the subarachnoid space and with recombinant adenoviruses that transduce pia mater cells. Second, the phenotype of nociceptive neurons has been altered by recombinant herpes viruses overexpressing antinociceptive peptides or reducing expression of endogenous nociceptive molecules. Both approaches attenuate or reverse persistent nociceptive states, suggesting use in the development of genetic therapy for pain management in humans.

Hydrotherapy in labor

Maternal anxiety and pain prolong labor and contribute to fetal distress. Hydrotherapy during labor may promote relaxation and decrease pain without the risks caused by other treatments. In this pilot study the psychophysiological effects of hydrotherapy on maternal anxiety and pain during labor were examined. Using a randomized, pretest-posttest control group design with repeated measures, 18 term parturients were assigned to a control or an experimental group. Experimental subjects were placed in a tub of 37 degrees C water for 1 hr during early labor. The Wilcoxon two-sample test revealed statistically significant effects. At 15 min bathers' anxiety and pain scores were decreased compared to nonbathers. At 60 min bathers' pain scores were decreased compared to nonbathers. After 15 min of immersion, bathers had a significantly greater increase in plasma volume than nonbathers. No significant differences were found in urine catecholamines or maternal-fetal complications. The small sample limits conclusions, but the findings offer preliminary support for the therapeutic effects of bathing in labor for acute, short-term anxiety and pain reduction.

Overexpression of proenkephalin in the amygdala potentiates the anxiolytic effects of benzodiazepines

To elucidate the role of opioid peptides in control of the anxiety-like behavior and anxiety-reducing actions of benzodiazepines, a recombinant, replication-defective herpes virus (SHPE) carrying human preproenkephalin cDNA was delivered to rat amygdala. Viral infection resulted in a strong, localized transgene expression after 2-4 days which diminished after one week. Anxiety-like behavior and the anxiolytic effect of diazepam were assessed three days after gene delivery using the elevated plus maze test. While SHPE infection alone did not reduce anxiety-like behavior, rats infected with SHPE exhibited a greater response to the anxiolytic effect of diazepam when compared to rats infected with a control virus (SHZ.1) containing the lacZ gene. The enhancement of diazepam action by SHPE was naloxone reversible, region-specific, and correlated with the time course of preproenkephalin expression. The findings implicate amygdalar opioid peptides in regulating the anxiolytic effects of benzodiazepines. This study also demonstrates the usefulness of recombinant herpes virus in evaluating the role of single gene products within specific brain sites in pharmacological responses and complex behaviors.

Changes in nociceptive and anxiolytic responses following herpes virus-mediated preproenkephalin overexpression in rat amygdala are naloxone-reversible and transient

These results using herpes virus-mediated gene transfer to overexpress enkephalin in the amygdala support the role of amygdalar opioids in the anxiolytic actions of benzodiazepines and supraspinal nociception (see ref. 1). These studies also demonstrate the usefulness of recombinant herpes virus in evaluating the role of single gene products within specific brain sites in pharmacological responses and complex behaviors.

Antihyperalgesic effects of infection with a preproenkephalin-encoding herpes virus

To test the utility of gene therapeutic approaches for the treatment of pain, a recombinant herpes simplex virus, type 1, has been engineered to contain the cDNA for an opioid peptide precursor, human preproenkephalin, under control of the human cytomegalovirus promoter. This virus and a similar recombinant containing the Escherichia coli lacZ gene were applied to the abraded skin of the dorsal hindpaw of mice. After infection, the presence of beta-galactosidase in neuronal cell bodies of the relevant spinal ganglia (lacZ-containing virus) and of human proenkephalin (preproenkephalin-encoding virus) in the central terminals of these neurons indicated appropriate gene delivery and expression. Baseline foot withdrawal responses to noxious radiant heat mediated by Adelta and C fibers were similar in animals infected with proenkephalin-encoding and beta-galactosidase-encoding viruses. Sensitization of the foot withdrawal response after application of capsaicin (C fibers) or dimethyl sulfoxide (Adelta fibers) observed in control animals was reduced or eliminated in animals infected with the proenkephalin-encoding virus for at least 7 weeks postinfection. Hence, preproenkephalin cDNA delivery selectively blocked hyperalgesia without disrupting baseline sensory neurotransmission. This blockade of sensitization was reversed by administration of the opioid antagonist naloxone, apparently acting in the spinal cord. The results demonstrate that the function of sensory neurons can be selectively altered by viral delivery of a transgene. Because hyperalgesic mechanisms may be important in establishing and maintaining neuropathic and other chronic pain states, this approach may be useful for treatment of chronic pain and hyperalgesia in humans.

Herpes virus-mediated preproenkephalin gene transfer to the amygdala is antinociceptive

To evaluate the role of the amygdala in pain modulation and opioid-mediated antinociception, a recombinant, replication-defective herpes virus carrying the human preproenkephalin cDNA was injected bilaterally into the rat amygdala. Four days after gene delivery nociceptive behavior was assessed by the formalin test. Rats infected with the virus expressing preproenkephalin showed a selective, naloxone-reversible abolition of phase 2 flinching behavior compared to rats infected with a control virus. The results implicate the amygdala in the control of pain and in opioid analgesia and demonstrate the use of recombinant herpes viruses as tools for studying gene function in specific neural pathways of the central nervous system.

Toxicity of acid-sulfate soil leachate and aluminum to embryos of the Sydney Rock oyster

The toxicity of leachate water from acid-sulfate soil to the early embryonic development of the Sydney Rock oyster, Saccostrea commercialis, was assessed. Concentrations of acid-sulfate soil leachate water as low as 3.3% in seawater were found to decrease the normal development of oyster embryos after 48 hr exposure, and this effect could not be attributed to any significant change in pH or salinity. An EC50 value for the acid-sulfate soil leachate water of 2.5 to 2.9% in seawater was obtained, and the no observed effect concentration was determined at a concentration of 2% in seawater. In tests conducted with aluminum added to seawater, a significant decrease in the percentage of embryos developed to the D-veliger stage occurred at concentrations of 150 micrograms/liter and greater, with no effects at 100 micrograms/liter. An EC50 of 225 micrograms/liter for the effect of added aluminum on embryo survival was obtained and all embryos showed developmental abnormalities at concentrations of 400 micrograms/liter and greater. A significant decrease in the embryonic development occurred when the fertilized eggs were incubated in pH-adjusted seawater at pH values < or = 6.75, but no significant effects were found at pH 7.0 or above. Since aluminum was present in high concentrations in the acid-sulfate soil leachate water, it was concluded that aluminum was the main toxicant in the acid-sulfate water that disrupted the oyster embryonic development.

Toxicity of acid-sulphate soil leachate and aluminium to the embryos and larvae of Australian bass (Macquaria novemaculeata) in estuarine water

The toxicity of leachate water from acid-sulphate soil to the early life stages of Australian bass, Macquaria novemaculeata, incubated in seawater was evaluated. Acid-sulphate soil leachate water (pH> or =6.8) delayed the hatching of fertilised eggs, but after 48 h the per cent hatching was normal. In comparison, acidic saline water (25 per thousand salinity) at pH 4.0 or less prevented embryos from hatching. The survival of yolk-sac larvae exposed to acid-sulphate soil leachate water at a concentration of 32% in seawater and an initial pH of 7.2, was significantly different to controls after 96 hours. In corresponding tests with only acidified saline water (20 per thousand salinity), pH levels equal to or below 5.0 killed yolk-sac larvae after 96 h exposure. Aluminum showed a pH dependent toxicity to yolk-sac larvae, with added aluminium as low as 200 microg litre(-1) having a significant effect on larval survival at pH 5.5, and concentrations of 600-800 microg litre(-1) having a significant effect on larval survival at an initial pH range of 6.0 < pH < 6.8. It was concluded that significant mortality of the early life stages of Australian bass would occur if they are exposed to acid-sulphate soil leachate that results in a pH in the receiving estuarine water below 5.5, or when the pH is below 6.8 and aluminium is present at a total concentration of 800 microg litre(-1) or greater.

Culture and class influences on Anglo and Puerto Rican mothers' beliefs regarding long-term socialization goals and child behavior

These 2 studies examine culture and socioeconomic status as simultaneous possible sources for group differences in mothers' beliefs regarding desirable and undesirable long-term socialization goals and child behavior. In Study 1, 100 mothers of young toddlers aged 12-24 months from 5 sociocultural groups participated: middle- and lower-class Anglo, middle- and lower-class island Puerto Rican, and lower-class migrant Puerto Rican. Results indicate that culture and socioeconomic status contribute independently to group differences, but that cultural effects appear to be stronger. Study 2 examined cultural differences in perceptions of behaviors using middle-class Anglo and Puerto Rican mothers only. The findings support those of Study 1, suggesting that Anglo and Puerto Rican mothers place differential value on the constructs of Self-Maximization and Proper Demeanor, even when socioeconomic status is controlled for. The findings of these studies have important implications for the culturally sensitive study of the relation between parental beliefs and behaviors.

Initial processing of human proenkephalin in bovine chromaffin cells

The opioid peptide precursor preproenkephalin (PPE) contains seven enkephalin sequences and is synthesized by epinephrine-producing adrenal chromaffin cells and various peripheral and central neurons. After removal of its signal peptide, PPE undergoes processing at dibasic amino acid sites to yield its final opioid products-Met-enkephalin, Leu-enkephalin, and various larger, enkephalin-containing peptides. Processing of PPE was examined in bovine chromaffin cells using a plasmid containing the human PPE (hPPE) cDNA under the control of the cytomegalovirus immediate early enhancer/promoter. Following transfection of this hPPE-containing plasmid into bovine chromaffin cells, several proenkephalin-immunoreactive bands were observed on western blots with monoclonal antibodies that recognize human, but not bovine, proenkephalin sequences. The pattern of hPPE-derived peptides observed was similar to that of bovine PPE processing products. A series of recombinant plasmids containing mutations in the hPPE sequence at putative processing sites was then constructed. Conversion of Lys-Lys and Lys-Arg sequences to Lys-Gln and of Arg-Arg to Arg-Gln altered initial hPPE processing at only three of the putative processing sites. When hPPE cDNA containing mutations at all of these initially processed sites was expressed, one or more alternative processing sites were revealed. These data suggest the importance of structural features in addition to the dibasic sequences that limit the processing of proenkephalin.

Increased open field locomotion and decreased striatal GABAA binding after activity wheel running

Open-field behavior has been used to model reductions in anxiety-related behaviors in the rat after chronic physical activity. Plausible mechanisms for the increased open field locomotion observed after physical activity have not been studied. Open field locomotion is decreased by gamma-aminobutyric acid (GABA) and its agonists, and increased by GABA antagonists, in the ventral striatum. Hence, we tested the hypothesis that increased open field locomotion following chronic physical activity would be accompanied by a decrease in the number of GABAA receptors in the corpus striatum. Young (approximately 55 days) male Sprague-Dawley rats (N = 24) were randomly assigned to three conditions: 24-h access to an activity wheel (AW), running for 1 h without shock 6 days/week on a motorized treadmill (TM), or sedentary control (C). Open field locomotion (total and center squares traversed), defecation, and urination were assessed on each of 3 consecutive days prior to and again after 8 weeks of physical activity. Open field locomotion (total and center squares) increased after activity wheel running, decreased after treadmill training, and did not change for control animals. GABAA receptor density indicated by [3H] bicuculline binding (fmol/mg) was lower for activity wheel animals compared with treadmill animals and controls. GABA concentration (mumol/g) was not different between activity wheel and treadmill groups but was higher for both groups contrasted with controls. Our findings of decreased GABAA density in the corpus striatum concomitant with an increase in open field locomotion are consistent with an anxiolytic effect of chronic activity wheel running.

Effects of benzodiazepine agonist exposure on corticotropin-releasing factor content and hormonal stress responses: divergent responses in male and ovariectomized female rats

Benzodiazepine agonists affect endocrine responses of the hypothalamic-pituitary-adrenal axis and can antagonize many of the actions of corticotropin-releasing factor (CRF). Gender and gonad-related factors can influence both the development of tolerance to the benzodiazepines in rats and the concomitant neural adaptations associated with chronic benzodiazepine agonist exposure. This study compared changes in CRF content, corticosterone release and ACTH levels after diazepam exposure in ovariectomized female (OVX) and male rats. After treatment with diazepam for 3 days (acute) or 3 weeks (chronic), content of CRF immunoreactivity in eight brain areas and serum corticosterone were determined by radioimmunoassay in handling-habituated rats. The effects of acute and chronic benzodiazepine exposure on swim stress-induced corticosterone and ACTH release were also examined. Chronic diazepam exposure reduced stress-induced corticosterone and ACTH release in OVX, but not male, rats. Acute diazepam exposure similarly attenuated stress-induced corticosterone release in OVX rats, but did not affect ACTH release. OVX control groups had greater levels of CRF than males in several brain regions. Gender-specific alterations in CRF content after chronic diazepam exposure were observed in amygdala, locus ceruleus and median eminence. Chronic benzodiazepine agonist exposure increased CRF levels in the amygdala of OVX rats, but not males. Both chronic and acute diazepam exposure increased CRF content in the locus ceruleus of male, but not OVX, rats. These results indicate that the effects of benzodiazepine exposure on neural CRF systems are region specific and influenced by gender-related factors.

Stimulatory regulation of the large-conductance, calcium-activated potassium channel by G proteins in bovine adrenal chromaffin cells

G proteins regulate the electrical activity of various cells through their actions on membrane ion channels. In the present study, the effect of G proteins was examined on unitary, large conductance (BK), Ca(2+)-activated K+ channels measured in excised, inside-out patches of membrane obtained from cultured bovine adrenal chromaffin cells. Cytoplasmic application of either guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) or AlF-4 to stimulate G proteins resulted in a > 4-fold increase in the open probability of the BK channel measured at +40 mV in the presence of a 1 microM concentration of Ca2+. A similar stimulatory regulation was observed after the addition of an activated, mixed Gi/Go alpha preparation. The increase in the open probability during G protein stimulation was associated with a large reduction in the duration of a long closed state of the channel and could be observed in the presence of a protein kinase inhibitor. The half-maximal voltage required for steady state activation of the BK channel decreased from +63 mV to +48 mV in the presence of GTP gamma S. In addition, the half-maximal Ca2+ concentration required for channel opening was reduced from 11.7 microM in control measurements to 1.3 microM during regulation by GTP gamma S. Thus, G proteins increase the open probability of the chromaffin BK Ca(2+)-activated K+ channel by shifting the voltage dependence of channel gating to more negative potentials and by enhancing the affinity of the channel for Ca2+. Stimulatory regulation may provide a compensatory mechanism for decreasing the action potential duration during secretagogue-mediated exocytosis.

Rosenthal fiber encephalopathy presenting with demyelination and Rosenthal fibers in a solvent abuser: adult Alexander's disease?

We report a neuropathological case of the brain of a 22-year-old male solvent abuser. He had also been diagnosed as suffering from schizophrenia. Neurohistology revealed the presence of Rosenthal fibers (RFs) in subpial and perivascular collections in the medulla, the floor of the 3rd and 4th ventricles, and also in the spinal cord. There was mild demyelination in the frontal, temporal, and parietal lobes, as well as the left dorsal column in the spinal cord. There was bilateral basal ganglia calcification. Demyelination and RFs have been the hallmark of the diagnosis of adult Alexander's disease. We urge that these are insufficient criteria for this nosological category, and suggest the alternative and more appropriate label of Rosenthal fiber encephalopathy. In view of the known toxic, clinical effects of chronic solvent abuse, and the lack of knowledge of the neuropathological effects, we also tentatively note the association of the solvent abuse with the neuropathology, but are unable to assert any causal link.

Optimization of calcium phosphate transfection for bovine chromaffin cells: relationship to calcium phosphate precipitate formation

Optimal conditions for formation of calcium phosphate-DNA precipitates and for chromaffin cell transfection by the calcium phosphate method were examined. A relationship was observed between turbidity of calcium phosphate solutions and the ability of calcium phosphate-DNA mixtures to give efficient transfection of bovine chromaffin cells. Under optimal conditions up to 35% of chromaffin cells in cultures transfected with plasmid DNA encoding human proenkephalin or Escherichia coli beta-galactosidase expressed the respective proteins. Important factors for transfection were the pH (6.95) and buffer employed for calcium phosphate-DNA precipitate formation, the amount and type of DNA, and the absence of serum in the cultures. Additionally, phosphate and calcium concentrations in the culture medium during incubation of cells with DNA are critical. Optimal conditions for transfection of chromaffin cells were also useful for transfection of clonal BSC-40 cells, an African green monkey kidney cell line. These results suggest that the optimal conditions described here for chromaffin cells may have broad applicability to other cell types. In addition, the results suggest that it is possible to optimize the solutions used for transfection conditions by monitoring calcium phosphate formation.

The exponentiation formula of reliability and survival: does it always hold?

In reliability and biometry, it is common practice to choose a failure model by first assessing the failure rate function subjectively, and then invoking the well known "exponentiation formula". The derivation of this formula is based on the assumption that the underlying failure distribution be absolutely continuous. Thus, implicit in the above approach is the understanding that the selected failure distribution will be absolutely continuous. The purpose of this note is to point out that the absolute continuity may fail when the failure rate is assessed conditionally, and in particular when it is conditioned on certain types of covariates, called "internal covariates". When such is the case, the exponentiation formula should not be used.

Processing of proenkephalin in bovine chromaffin cells occurs in two phases

The processing of proenkephalin was studied in primary cultures of bovine adrenal medullary chromaffin cells by pulse-chase radiolabeling, immunopurification of proenkephalin and derivative peptides and quantitation following gel electrophoresis and Western blotting. Proenkephalin was processed with a t1/2 of approximately 1.1 h. Processing of proenkephalin-derived peptides of 15-25 kDa was essentially complete by 1 h. Treatment of chromaffin cells with brefeldin A to block the intracellular transport of proteins or with ammonium chloride to neutralize acidic intracellular compartments had only minor effects on the initial processing of proenkephalin. In contrast, both of these agents prevented a second, slower phase of proenkephalin processing. These studies suggest that proteolytic processing of proenkephalin in bovine adrenal medullary cells starts before transport to the trans-Golgi network and packaging into the chromaffin granules. A second phase of processing that requires an acidic environment occurs in or distal to the trans-Golgi network.

Integrin-mediated collagen gel contraction by cardiac fibroblasts. Effects of angiotensin II

Angiotensin II (Ang II), a vasoactive octapeptide, has been implicated in cardiac growth and the development of hypertrophy and fibrosis secondary in hypertensive disease. These consequences of Ang II imply an effect on the function and morphology of cardiac interstitial cells (fibroblasts). The present investigation was designed to (1) determine whether neonatal heart fibroblasts (NHFs) possess functional Ang II receptors on their plasma membrane and (2) examine the effects of Ang II on NHFs in vitro using three- and two-dimensional (3D and 2D, respectively) cultures. Several analytic techniques were used to test the specific questions of the present study. Since cardiac fibroblast phenotype can be influenced by culture conditions, both 2D and 3D cultures were used in the present investigations. Reverse-transcriptase polymerase chain reaction and radioligand binding analysis were used to test for the presence of Ang II receptors on NHFs. Both revealed that NHFs in 2D culture possess Ang II receptor mRNA and Ang II receptors. When isolated NHFs were cultured in 3D collagen gels and treated with Ang II, gel contraction was stimulated by NHFs. This effect was attenuated by the specific Ang II receptor antagonist [Sar1,Ala8]Ang II. Ang II-stimulated gel contraction was completely inhibited by extracellular matrix receptor (beta 1-integrin) antibodies (P < .05), supporting previous studies indicating that collagen gel contraction is mediated via the integrins. Immunofluorescent staining was used to test the localization of cell-surface integrins. A more intense staining pattern for beta 1-integrin in Ang II-treated versus control cells was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

A G protein-activated K+ current in bovine adrenal chromaffin cells: possible regulatory role in exocytosis

Guanine nucleotide binding proteins (G proteins) act as signal transducers between membrane receptors and ion channels. In the present study, the whole-cell arrangement of the patch clamp technique was used to examine the effect of G proteins on K+ channels in cultured bovine adrenal chromaffin cells. Internal dialysis of chromaffin cells with guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) or external application of AIF-4, to stimulate G proteins, resulted in a voltage-dependent increase in the amplitude of the outward K+ currents. The half-maximal voltage required for activation of the currents was shifted by -16 mV in the presence of GTP gamma S. The augmentation in the K+ currents was accompanied by the appearance of a fast component of current activation measured at potentials positive to 0 mV. The GTP gamma S-sensitive current could not be detected when internal K+ was replaced with Cs+ and was reversibly inhibited by tetraethylammonium (IC50, 2 mM). In contrast, the scorpion venom charybdotoxin (50 nM) and the bee venom apamin (250 nM) only slightly reduced the K+ currents during stimulation by GTP gamma S and did not alter the activation kinetics. In addition, the GTP gamma S-sensitive K+ current could be activated in the absence of internal Ca2+ and when the inward Ca2+ current was inhibited with CdCl2. Treatment of the chromaffin cells with fluoride decreased nicotine-evoked secretion of catecholamines in a concentration-dependent manner. Thus, bovine chromaffin cells contain a G protein-stimulated K+ channel that may play a regulatory role in secretagogue-mediated exocytosis.

Pertussis toxin enhances proenkephalin synthesis in bovine chromaffin cells

The synthesis of the neuropeptide precursor proenkephalin was measured in bovine adrenal chromaffin cells following radiolabeling with [35S]methionine. Treatment of chromaffin cells with pertussis toxin (100 ng/ml) approximately doubled proenkephalin synthesis without altering total protein synthesis. Pertussis toxin pretreatment also increased proenkephalin synthesis in chromaffin cells exposed to vasoactive intestinal peptide (VIP) and 3-isobutyl-1-methylxanthine (IBMX). Combinations of IBMX plus nicotine, VIP, or histamine also synergistically enhanced proenkephalin synthesis, with no further elevation when the cells were also pretreated with pertussis toxin. The action of forskolin, a direct activator of adenylate cyclase, on proenkephalin synthesis was similarly potentiated by pertussis toxin or IBMX, presumably reflecting the abilities of both the toxin and this phosphodiesterase inhibitor to enhance the cyclic AMP response to forskolin. In contrast, increased synthesis of proenkephalin in response to phorbol esters was not affected by pertussis toxin treatment. These results suggest that pertussis toxin potentiates proenkephalin synthesis primarily through inactivation of guanine nucleotide-binding proteins that inhibit adenylate cyclase, although other signaling pathways may also be involved.

Exercise training alters cardiovascular and hormonal responses to intracranial self-stimulation

Both reinforcing intracranial self-stimulation (ICSS) and physical exercise result in heightened cardiovascular and endocrine responses. This study compared the cardiovascular and endocrine responses to ICSS in rats after either chronic ICSS or treadmill running. Male rats (n = 35) were implanted with bipolar electrodes aimed at the ventral tegmental area of the brain, and those that performed vigorous lever pressing for ICSS (> 50 presses/min; n = 30) were counter balanced into three groups: chronic ICSS (PRESS), chronic run training (RUN), or sedentary controls (CONT). PRESS, RUN, and CONT rats performed ICSS, ran on a motorized treadmill, or sat quietly in cages for 30 min/day, 5 day/wk, for 12 wk, respectively. All animals then performed 30 min of lever pressing for ICSS and were immediately killed. Oxygen consumption, heart rate, blood pressure, rectal temperature, and plasma norepinephrine, epinephrine, and corticosterone increased (P < 0.05) for all groups during lever pressing. PRESS rats did not differ from CONT rats for any variable studied. However, heart rate was lower and oxygen consumption, norepinephrine, and corticosterone were higher in RUN than in CONT rats. Heart and ventricle weights were higher in PRESS and RUN than in CONT rats; body weights were not different. These data suggest that chronic treadmill running results in adaptations that influence cardiovascular and hormonal responses to ICSS.

Clinical classification as a predictor of therapeutic outcome after cervical epidural steroid injection

A retrospective analysis was done on 100 patients who had received cervical epidural steroid injections for neck pain and cervical radiculopathy to identify the predictors of outcome after such treatment. Potential predictors of outcome were assessed individually and then simultaneously with a multiple-regression model. Patients with radicular symptoms and signs had the best pain relief in contradistinction to those with axial (neck) pain. A clinical classification model predicting the outcome and an algorithm for the use of such injections in the treatment of cervical radiculopathy were developed.

Effects of intracranial self-stimulation on selected physiological variables in rats

The purpose of this investigation was to characterize selected metabolic, cardiovascular, and hormonal responses to reinforcing intracranial self-stimulation (ICSS) of the ventral tegmental area (VTA) in rats. Twenty male Sprague-Dawley rats were stereotaxically implanted with bipolar electrodes aimed at the VTA of the brain. Rats were trained to lever-press for ICSS for 1 wk. While they adapted to the experimental environment by sitting in a metabolic operant chamber, they were connected to the electrode cable but did not lever-press. All animals were instrumented with arterial catheters. Rats receiving contingent stimulation (C-St; n = 10) performed 30 min of lever pressing in the metabolic operant chamber for reinforcing brain stimulation. Oxygen consumption (VO2), heart rate (HR), mean arterial pressure (MAP), and rectal temperature (Trec) increased with the onset and continuation of contingent brain stimulation over 30 min (P < 0.05). In addition, plasma norepinephrine (NE), epinephrine (Epi), and corticosterone increased significantly above resting values in C-St rats (P < 0.05). Five animals received investigator-delivered reinforcing brain stimulation (noncontingent stimulation; NC-St), with MAP, HR, VO2, NE, and Epi increasing significantly above resting values (P < 0.05). Trec and corticosterone were not responsive to noncontingent brain stimulation. With the exception of HR, nonstimulated controls (n = 5) did not experience increases above resting values in any of the variables measured. The responses suggest that contingent brain stimulation reward elicits heightened sympathetic arousal.(ABSTRACT TRUNCATED AT 250 WORDS)

Vasoactive intestinal peptide is a secretagogue in bovine chromaffin cells pretreated with pertussis toxin

Vasoactive intestinal peptide (VIP) evokes little or no secretion of catecholamines from cultured bovine chromaffin cells. However, pretreatment of chromaffin cells with pertussis toxin (PTX, 100 ng/ml for > or = 4 h) revealed that VIP is a secretagogue. In PTX-treated cells catecholamine secretion evoked by VIP occurs with minimal elevation of cyclic AMP and is only slightly enhanced by cyclic nucleotide phosphodiesterase inhibitors. Forskolin, a direct activator of adenylate cyclase, causes delayed secretion of catecholamines from chromaffin cells treated with PTX, but only with pronounced elevation of cyclic AMP levels. Stimulation of catecholamine secretion by histamine, known to activate phosphatidylinositol-specific phospholipase C in chromaffin cells, is also enhanced by preincubation of the cells with PTX. These results suggest that in the bovine chromaffin cell a PTX-sensitive G-protein mediates tonic inhibition of secretion, possibly by preventing activation of phospholipase C.

The effects of nimodipine on cocaine toxicity

The response to nimodipine as an inhibitor of cocaine toxicity was investigated in pentobarbital-anesthetized dogs and in isolated dog heart preparations at constant heart rates. Nimodipine (10 micrograms/kg) markedly decreased peripheral and coronary vascular resistance and increased cardiac output, cardiac work, and coronary blood flow. When corrected for the change in afterload, nimodipine had a positive inotropic response, as measured by +/- maximal dP/dt, in the cocaine-depressed animal. Thus, cocaine toxicity was partially reversed by nimodipine. In the isolated heart preparation, nimodipine resulted in further cardiac depression similar to that seen with other calcium channel antagonists.

Comparative incorporation of proenkephalin-derived peptides, chromogranin A, and dopamine beta-hydroxylase into chromaffin vesicles

The incorporation of enkephalin-containing peptides (ECPs) derived from proenkephalin into chromaffin vesicles was examined in primary cultures of adrenal medullary chromaffin cells. Cells were pulse-labeled with [35S]methionine and chased for periods up to 24 h. Chromaffin vesicles in cell homogenates were then fractionated by density gradient centrifugation and the presence of [35S]Met-enkephalin sequences in gradient fractions determined. 35S-ECPs were incorporated into particles suggestive of immature vesicles within 1-2 h after radiolabeling. Vesicle maturation, measured by co-equilibration of 35S-ECPs and total ECPs in the gradients, was complete within 9-12 h and was unaffected by treatments that increase proenkephalin synthesis. Incorporation of [35S]chromogranin A into chromaffin vesicles followed a similar time course, but 35S-labeled dopamine beta-hydroxylase was much more slowly incorporated, possibly reflecting differences in incorporation of membrane and soluble components. In summary, the data demonstrate that ECPs are rapidly sequestered in immature chromaffin vesicles, a process unaltered by changing rates of proenkephalin synthesis.

Processing of proenkephalin in adrenal chromaffin cells

The processing of proenkephalin was studied using [35S]methionine pulse-chase techniques in primary cultures of bovine adrenal medullary chromaffin cells. Following radiolabeling, proenkephalin-derived peptides were extracted from the cells and separated by reverse-phase HPLC. Fractions containing proenkephalin fragments were digested with trypsin and carboxypeptidase B to liberate Met-enkephalin sequences and subjected to a second HPLC step to demonstrate association of radiolabel with Met-enkephalin. Processing of proenkephalin is complete within 2 h of synthesis, suggesting completion at or soon after incorporation into storage vesicles. Pretreatment of the cells with nicotine, histamine, or vasoactive intestinal peptide to enhance the rate of proenkephalin synthesis failed to alter the time course of processing and had minimal effects on the distribution of products formed. Addition of tetrabenazine, an inhibitor of catecholamine uptake into chromaffin vesicles, during radiolabeling and a 6-h chase period caused enhanced proenkephalin processing. These results suggest that the full range of proenkephalin fragments normally found in the adrenal medulla (up to 23.3 kDa) represents final processing products of the tissue and that termination of processing may depend on the co-storage of catecholamines.

Regulation of proenkephalin synthesis in adrenal medullary chromaffin cells

The synthesis of proenkephalin was assessed in primary cultures of bovine adrenal medullary chromaffin cells by incubation of the cells with [35S]methionine, digestion of proenkephalin-derived peptides with trypsin and carboxy-peptidase B, and quantitation of radioactivity incorporated into Met-enkephalin following reversed-phase HPLC. Nicotine, histamine, and vasoactive intestinal peptide each enhanced the rate of proenkephalin synthesis approximately 10-fold when examined between 16 and 32 h after the drug or hormone addition. Inclusion of nifedipine (1 microM) partially blocked the stimulatory effect of nicotine, but not that of vasoactive intestinal peptide or histamine, or proenkephalin synthesis. Theophylline, tetrabenazine, and angiotensin II also increased the rate of proenkephalin synthesis (three- to eight-fold). These increases in the apparent rate of proenkephalin synthesis were not attributable to altered [35S]methionine specific radioactivity or rates of turnover and did not reflect similar increases in total protein synthesis. The half-life for turnover of Met-enkephalin sequences was 3-4 days in the cultured chromaffin cell. These studies directly show that proenkephalin synthesis is the primary regulatory step in control of chromaffin cell opioid peptide content.

Insulin-like growth factor I enhances proenkephalin synthesis and dopamine beta-hydroxylase activity in adrenal chromaffin cells

Insulin-like growth factor I (IGF-I) increased both the contents of proenkephalin-derived enkephalin-containing peptides and the activity of dopamine beta-hydroxylase in bovine adrenal chromaffin cells. These increases in dopamine beta-hydroxylase and enkephalin-containing peptides continued for at least 8 days. The half-maximal IGF-I concentration for these effects was approximately 1 nM, with maximal effects observed at 10-30 nM. In contrast, insulin was 1000-fold less potent. Pretreatment of chromaffin cells with IGF-I increased the rate of [35S]proenkephalin synthesis 4-fold compared to untreated cells. Total protein synthesis increased only 1.5-fold under these conditions. These results suggest that IGF-I may be a normal regulator of chromaffin cell function.

Metal ion co-ordination in the DNA binding domain of the yeast transcriptional activator GAL4

The structure of the DNA binding domain of the yeast transcriptional activator GAL4 was investigated by extended X-ray fine structure (e.x.a.f.s.). Two samples of GAL4 were studied, one containing cadmium as a structural probe (Cd(II)GAL4) and the other containing the 'native' zinc (Zn(II)-GAL4). The results suggest that the structure of the DNA binding domain of GAL4 contains a two metal ion cluster distinguishing it from the 'zinc finger' proteins typified by the Xenopus laevis transcription factor TFIIIA.