Ipsilateral turning behavior induced by unilateral microinjections of a cannabinoid into the rat subthalamic nucleus

The subthalamic nucleus contains cannabinoid receptors and cannabinoid receptor mRNA. However, the role of cannabinoid receptors in this nucleus has not been examined. In order to investigate the functional role of cannabinoid receptors in the rat subthalamic nucleus, turning activity was observed following unilateral microinjection of the synthetic cannabinoid CP 55,940. CP 55,940 (10 microg) induced ipsilateral turning. This effect was blocked by coadministration of the cannabinoid receptor antagonist SR141716A (5 microg). These results suggest that cannabinoid receptors in the subthalamic nucleus mediate an inhibition of motor activity.

An antiviral protein from Bougainvillea spectabilis roots; purification and characterisation

An antiviral protein active against mechanical transmission of tomato spotted wilt virus was identified in the root tissues of Bougainvillea spectabilis Willd. Bougainvillea Antiviral Protein I (BAP I) was purified to apparent homogeneity from the roots of Bougainvillea by ammonium sulphate precipitation, CM- and DEAE-Sepharose chromatography and reverse phase HPLC. BAP I is a highly basic protein (pI value > 8.6) with an Mr of 28,000. The N-terminal sequence of BAP I showed homology with other plant antiviral proteins. Preliminary tests suggest that purified BAP I is capable of interfering with in vitro protein synthesis.

Prolonging the delayed phase of myocardial protection: repetitive adenosine A1 receptor activation maintains rabbit myocardium in a preconditioned state

OBJECTIVES

This study was designed to examine whether the myocardium can be maintained in a protected state by extending the delayed phase of cardioprotection with chronic, intermittent adenosine A1 receptor activation.

BACKGROUND

Several recent studies have explored the temporal characteristics of the protective effects of ischemic preconditioning. Two distinct phases of myocardial protection have been described: the short-lived immediate phase, or "classic" preconditioning, and the delayed phase, or "second window of protection" (SWOP). Previous studies have examined the potential for extending the duration of classic preconditioning by repeated application of the preconditioning stimulus. Pretreatment with either multiple episodes of ischemia or continuous infusion of a selective adenosine A1 receptor agonist, 2-chloro-N6-cyclopentyladenosine (CCPA), resulted in attenuation of the protective effects of preconditioning, implying downregulation of the receptors involved in triggering classic preconditioning.

METHODS

Male New Zealand White rabbits were treated with repeated intravenous boluses of CCPA, 100 microg/kg body weight, or 0.9% saline at 48-h intervals. Forty-eight hours after the fifth dose (day 10), the animals were anesthetized and subjected to 30 min of coronary occlusion, followed by 120 min of reperfusion. Infarct size was determined as a percentage of myocardial risk volume using tetrazolium staining. To further explore whether the rabbits had developed tolerance to the effects of adenosine A1 receptor activation, a subgroup of animals were treated with a further bolus of CCPA, 100 microg/kg, at the end of the reperfusion period, and the hemodynamic response was monitored for 10 min before excision of the heart.

RESULTS

Pretreatment with intermittent doses of CCPA resulted in a 42% reduction in the infarct to risk ratio compared with vehicle pretreatment (26.6+/-3.7% vs. 45.9+/-5.5%, p < 0.01). Furthermore, CCPA treatment at the end of reperfusion resulted in identical hypotension and bradycardia in both groups.

CONCLUSIONS

We conclude that rabbits can be maintained in a protected state against myocardial infarction by repeated activation of adenosine A1 receptors, with no evidence of tachyphylaxis to the infarct-limiting or hemodynamic effects of CCPA. This finding suggests that adenosine A1 receptor activation may hold promise as a new approach to long-term cardioprotection.

Immunohistochemical distribution of cannabinoid CB1 receptors in the rat central nervous system

Immunohistochemical distribution of cannabinoid receptors in the adult rat brain was studied using specific purified antibodies against the amino-terminus of the CB1 receptor. Our results generally agree well with the previous studies using CB1 receptor autoradiography and messenger RNA in situ hybridization. However, because of its greater resolution, immunohistochemistry allowed identification of particular neuronal cells and fibers that possess cannabinoid receptors. CB1-like immunoreactivity was found in axons, cell bodies and dendrites, where it appeared as puncta in somata and processes. Both intensely and moderately or lightly stained neurons were observed. The intensely stained neurons were dispersed and only occur in cortical structures including hippocampal formation and olfactory bulb. Moderately or lightly stained neurons were found in caudate-putamen and amygdala. In the hippocampal formation only intensely stained neurons were observed. The cell bodies of pyramidal neurons in CA1 and CA3 fields appeared to be unstained but surrounded by a dense plexus of immunoreactive fibers. The granule cells in the dentate area were also immunonegative. Many intensely stained neurons were located at the base of the granule cell layer. CB1-like immunoreactive neurons and fibers were also found in the somatosensory, cingulate, perirhinal, entorhinal and piriform cortices, in claustrum, amygdaloid nuclei, nucleus accumbens and septum. Beaded immunoreactive fibers were detected in periaqueductal gray, nucleus tractus solitarius, spinal trigeminal tract and nucleus, dorsal horn and lamina X of the spinal cord. A triangular cap-like mass of immunoreactivity was found to surround the basal part of the Purkinje cell body in the cerebellum. Only small, lightly stained cells were found in the molecular layer in the cerebellum close to the Purkinje cell layer. The CB1 receptor is widely distributed in the forebrain and has a more restricted distribution in the hindbrain and the spinal cord. It appears to be expressed on cell bodies, dendrites and axons. According to the location and morphology, many, but not all, CB1-like immunoreactive neurons appear to be GABAergic. Therefore, cannabinoids and cannabinoid receptors may play a role in modulating GABAergic neurons.

Cannabinoid receptor-mediated inhibition of the rat tail-flick reflex after microinjection into the rostral ventromedial medulla

Systemic administration of cannabinoids produce profound antinociception in rodents. The purpose of this study was to examine the contribution of the rostral ventromedial medulla (RVM) to cannabinoid-mediated inhibition of the tail-flick reflex. Rats received direct injections of two selective cannabinoid agonists, WIN55,212-2 and HU210, into the RVM. Both compounds significantly elevated tail-flick latencies by over 50%. WIN55,212-3, the inactive enantiomer, was without effect. Furthermore, co-administration of the selective cannabinoid receptor antagonist, SR141716A greatly attenuated the antinociception produced by HU210. Finally, injections of WIN55,212-2 outside the region of the RVM did not affect tail-flick latencies. These results demonstrate that the cannabinoid receptor system participates in the descending control of nociception and raise the possibility that actions of endogenous cannabinoids in the RVM may modulate nociceptive responsiveness.

Effects of intrapallidal cannabinoids on rotational behavior in rats: interactions with the dopaminergic system

The effect of unilateral intrapallidal cannabinoid receptor stimulation on rotational behavior in rats was explored. The potent cannabinoid agonist CP55,940 (5 microg/0.5 microl) induced ipsilateral turning when microinjected unilaterally into the globus pallidus. The D2 dopamine agonist quinpirole reversed this ipsilateral rotation but failed to affect motor behavior on its own. Finally, the D1 dopamine agonist SKF 82958 inhibited movement when administered into the globus pallidus, and this effect was not additive with CP55,940.

Changes in the male voice at puberty

The changes in the male voice in relation to the biological characteristics of puberty were assessed longitudinally in 26 boys. Speaking and singing fundamental frequencies were analysed in relation to the Tanner staging of puberty, saliva testosterone levels, and the Cooksey classification of voice analysis. There were abrupt changes in voice characteristics between Tanner stages G3 and G4 and more gradually from stages C3 to C5 of Cooksey. Although testosterone concentrations were not predictive of the changes, there was a correlation with testis volume. Voice fundamental frequencies were seen to change abruptly in late puberty, in contrast with previous studies. There is a good correlation between the Tanner and Cooksey methods of classification during male puberty.

Cloning and sequencing of aspartate aminotransferase from Thermus aquaticus YT1

A 39-base oligonucleotide "guessmer" probe, based on partial N-terminal sequence analysis of the aspartate aminotransferase purified from Thermus aquaticus strain YT1, was used to screen a genomic library prepared from T. aquaticus DNA. A 1842 bp DNA fragment was isolated that proved to contain the coding sequence for the aspartate aminotransferase. The gene is 1152 bases long and codes for a protein of 383 amino acid residues. The amino acid sequence obtained showed 88.7%, 45.1% and 32.9% identity of sequence with those of thermostable aspartate aminotransferases from T. thermophilus, Bacillus YM2, and Sulfolobus solfataricus, respectively. It showed 39.1% identity with one of the gene products tentatively identified as aspartate aminotransferase from the methanogenic archaebacterium Methanococcus jannaschii. Neither the amino acid compositions nor the aligned amino acid sequences provides any obvious clue as to the origin of thermal stability in this group of enzymes.

The effect of evisceration on visible contamination and the microbiological profile of fresh broiler chicken carcasses using the Nu-Tech Evisceration System or the conventional Streamlined Inspection System

Experiments were conducted to determine the effect of evisceration on visible contamination and the microbiological profile of fresh broiler chicken carcasses using the Nu-Tech System or the Streamlined Inspection System (SIS). Visible contamination was evaluated on the inside cavity and outside surface of 1,000 and 7,825 carcasses from Plants A and B, respectively, during 5 d of processing. For the microbiological study, in five separate trials, 80 broiler carcasses were collected each day from two processing plants (A and B). Two groups of 20 carcasses each were collected immediately prior to entering the Nu-Tech eviscerator, bagged separately, and 20 were labeled as NT1 and 20 as SIS1. The third group of 20 carcasses was collected immediately after the cropper on the Nu-Tech line and labeled NT2. For the fourth group, 20 carcasses were aseptically transferred from the Nu-Tech line just prior to evisceration, placed on the SIS line prior to evisceration, allowed to be eviscerated by the SIS eviscerator, collected immediately after the cropper, and labeled SIS2. Whole carcass rinses were conducted and aerobic plate counts (APC), total coliform counts (TC), total Escherichia coli counts (TEC), aerobic mesophilic impedance detection times (DT), and coliform impedance detection times (CDT) were determined within 30 h of collection. The Nu-Tech System was superior to SIS with regard to visible carcass contamination. For Plant A, evisceration using the Nu-Tech System or SIS did not significantly affect APC, TC, or TEC; however, evisceration using the Nu-Tech System resulted in an increase in DT and CDT (indicating a reduction in bacteria); whereas evisceration using SIS resulted in no significant decrease in bacterial levels. For Plant B, evisceration using the Nu-Tech resulted in lower APC, TC, TEC, and higher DT and CDT (indicating a reduction in bacteria); whereas evisceration using SIS resulted in no significant decrease in bacterial levels. Evisceration using the Nu-Tech System was at least equal to or in some cases better than SIS with regard to APC, TC, TEC, DT, and CDT.

Role of the subthalamic nucleus in cannabinoid actions in the substantia nigra of the rat

The effect of cannabinoids on the excitatory input to the substantia nigra reticulata (SNr) from the subthalamic nucleus was explored. For this purpose a knife cut was performed rostral to the subthalamic nucleus to isolate the subthalamic nucleus and the SNr from the striatum, a major source of cannabinoid receptors to the SNr. The data showed that the cannabinoid agonist WIN55,212-2 blocked the increase in the firing rate of SNr neurons induced by stimulation of the subthalamic nucleus with bicuculline. Furthermore, the cannabinoid antagonist SR141716A antagonized the effect of the cannabinoid agonist. This study showed that cannabinoids regulate not only the striatonigral pathway, as previously reported, but also the subthalamonigral pathway. The opposite influences of these two inputs to the SNr, inhibitory and excitatory respectively, suggest that endogenous cannabinoids play a major role in the physiological regulation of the SNr.

Endogenous cannabinoids as an aversive or counter-rewarding system in the rat

Human use of marijuana (Cannabis sativa) is widely assumed to have rewarding properties, a notion supported by its widespread recreational use. However, no study has clearly demonstrated such effects in animal models. The purpose of this study was to test for the presumed rewarding effect of cannabinoids using a conditioned place preference paradigm. The results showed that animals failed to develop place conditioning at a low dose (1.5 mg/kg) and developed a place aversion at a high dose (15 mg/kg) of the active principle in marijuana, delta 9-tetrahydrocannabinol (delta 9-THC), a finding consistent with most previous studies. Moreover, the administration of the cannabinoid antagonist SR141716A induced a conditioned place preference at both a low (0.5 mg/kg) and a high (5 mg/kg) dose. In summary, cannabinoid antagonism produced place preference while cannabinoid agonism induced place aversion. These results suggest that endogenous cannabinoids serve normally to suppress reward or to induce aversion.

Acute ischaemia: a dynamic influence on QT dispersion

BACKGROUND

The aim of this study was to test the hypothesis that acute myocardial ischaemia increases QT dispersion measured from the 12-lead electrocardiogram.

METHODS

Incremental atrial pacing was used to induce myocardial ischaemia in 18 patients with coronary artery disease and QT dispersion was measured. Six patients with normal coronary arteries served as the control group.

FINDINGS

All the patients with coronary artery disease developed angina and/or ST depression accompanied by marked increases in QT dispersion (mean increase 38 ms, 95% CI 30 to 45 ms, p < 0.001). In contrast, in the six patients with normal coronary arteries who remained without symptoms and without ST changes, there was no significant change in QT dispersion in response to pacing. Baseline QT dispersion did not distinguish those patients with coronary artery disease from those with normal coronary arteries (44 ms [95% Cl 39-49 ms] vs 40 ms [25-55 ms]), respectively.

INTERPRETATION

These results demonstrate that myocardial ischaemia induced by incremental atrial pacing in patients with coronary artery disease causes an acute increase in QT dispersion. Such "inducible" QT dispersion may prove more useful than resting QT dispersion in assessing the individual risk of arrhythmic events in patients with coronary artery disease.

Suppression of noxious stimulus-evoked activity in the ventral posterolateral nucleus of the thalamus by a cannabinoid agonist: correlation between electrophysiological and antinociceptive effects

The CNS contains a putative cannabinergic neurotransmitter and an abundance of G-protein-coupled cannabinoid receptors. However, little is known about the function of this novel neurochemical system. Cannabinold agonists produce antinociception in behavioral tests, suggesting the possibility that this system serves in part to modulate pain sensitivity. To explore this possibility, the effects of the cannabinoid agonist WIN 55,212-2 on nociceptive neurons in the ventroposterolateral (VPL) nucleus of the thalamus were examined in urethane-anesthetized rats. After identification of a nociresponsive neuron, a computer-controlled device delivered graded pressure stimuli to the contralateral hindpaw. WIN 55,212-2 (0.0625, 0.125, and 0.25 mg/kg, i.v.) suppressed noxious stimulus-evoked activity of VPL neurons in a dose-dependent and reversible manner. Noxious stimulus-evoked firing was affected more than spontaneous firing. These effects were apparently mediated by cannabinoid receptors, because the cannabinoid receptor-inactive enantiomer of the drug (WIN 55,212-3, 0.25 mg/kg) failed to alter the activity of this population of cells. Administration of morphine (0.5 mg/kg, i.v.) produced effects that were very similar to those produced by the cannabinoid. WIN 55,212-2 (0.25 mg/kg, i.v.) failed to alter the responses of non-nociceptive low-threshold mechanosensitive neurons in the VPL WIN 55,212-2 produced antinociceptive effects with a potency and time course similar to that observed in the electrophysiological experiments, despite the differences in the anesthetic states of the animals used in these experiments. The antinociceptive and electrophysiological effects on VPL neurons outlasted the motor effects of the drug. Furthermore, the changes in nociceptive responding could not be attributed to changes in skin temperature. Taken together, these findings suggest that cannabinoids decrease nociceptive neurotransmission at the level of the thalamus and that one function of endogenous cannabinoids may be to modulate pain sensitivity.

Systemic sclerosis associated with right ventricular cardiomyopathy

Systemic sclerosis is an uncommon multisystem disorder of unknown aetiology which predominantly affects the skin. Cardiac involvement, which is far more common than was originally realized, may affect any part of the heart but most frequently affects the left ventricular myocardium. Right ventricular dysfunction is usually associated with pulmonary vascular disease. We report a case of systemic sclerosis associated with right ventricular cardiomyopathy in whom pulmonary artery pressures were normal.

The Arabidopsis thaliana UBC7/13/14 genes encode a family of multiubiquitin chain-forming E2 enzymes

Covalent modification of proteins by attachment of multiubiquitin chains serves as an essential signal for selective protein degradation in eukaryotes. The specificity of ubiquitin-protein conjugation is controlled in part by a diverse group of ubiquitin-conjugating enzymes (E2s or UBCs). We have previously reported that the product of the wheat TaUBC7 gene recognizes ubiquitin as a substrate for ubiquitination in vitro, catalyzing the condensation of free ubiquitin into multiubiquitin chains linked via lysine 48 (van Nocker, S., and vierstra, R. D. (1991) Proc. Natl. Acad. Sci. U. S. A. 88, 10297-10301). Based on this activity, this E2 may play a central role in the ubiquitin proteolytic pathway by assembling chains in vivo. Here, we describe the cloning and characterization of a three-member gene family from Arabidopsis thaliana (designated AtUBC7/13/14) encoding structural homologs of TaUBC7. Like TaUBC7, recombinant AtUBC7/13/14 proteins formed multiubiquitin chains in vitro. AtUBC7/13/14 mRNAs were found in all tissues examined, and unlike related UBCs from yeast, the levels of mRNA were not elevated by heat stress or cadmium exposure. Transgenic Arabidopsis were engineered to express increased levels of active AtUBC7, for the first time altering the level of an E2 in a higher eukaryote. Plants expressing high levels of AtUBC7 exhibited no phenotypic abnormalities and were not noticeably enriched in multiubiquitinated conjugates. These findings indicate that the in vivo synthesis of multiubiquitin chains is not rate-limited by the abundance of AtUC7 and/or involves other, yet undefined components.

Electrophysiological effects of a cannabinoid on neural activity in the globus pallidus

The globus pallidus contains a dense distribution of cannabinoid receptors and appears to be a site of action of cannabinoids in the production of catalepsy. Single unit electrophysiology was used to explore the role of cannabinoid receptors in the globus pallidus of the rat. Intravenous injections of the potent and selective synthetic cannabinoid (R)-(+)-[2,3-dihydro-5-methyl-3-[(4-morpholinyl)methyl]-pyrrolo [1,2,3-de]-1,4-benzoxazin-6-yl](1-napthalenyl) methanone (WIN 55,212-2; up to 0.5 mg/kg, i.v.) inhibited the spontaneous firing of neurons in the globus pallidus. In a second set of experiments, WIN 55,212-2 antagonized the inhibition of pallidal firing produced by electrical stimulation of the striatum. The pharmacological specificity of the effects of WIN 55,212-2 on basal and evoked activity in the globus pallidus was demonstrated by the lack of effect of the inactive enantiomer WIN 55,212-3. These results indicate that cannabinoids may produce functionally opposite effects on spontaneous and evoked activity in the globus pallidus: a decrease in spontaneous firing and a decrease in the inhibition of firing produced by the striatopallidal projection.

Dissociation of the motor effects of (+)-pentazocine from binding to sigma 1 sites

Radioligand binding and behavioral studies were conducted to determine whether a relationship existed between the motor effects produced by (+)-pentazocine and its binding to sigma sites. Scatchard analyses revealed decreased [3H](+)-pentazocine binding in middle aged rats (5-6 months old) compared to young adult rats (2-3 months old). However, there was no difference between the extent of circling behavior or dystonia produced by microinjection of (+)-pentazocine into the substantia nigra or red nucleus in the older animals compared to the young adult rats. There was also a significant decrease in [3H](+)-pentazocine binding in rats chronically treated with haloperidol. Again, however, despite the reduction in [3H](+)-pentazocine binding, there was no difference between the extent of dystonia produced by unilateral intrarubral microinjection of (+)-pentazocine into animals chronically treated with haloperidol vs. saline. The postural changes produced by (+)-pentazocine could not be attenuated with coadministration of the putative sigma receptor antagonist BD1047 (N-[2-(3,4-dichlorophenyl)ethyl]-N-methyl-2-(dimethylamino) ethylamine), or the opiate receptor antagonist naloxone. However, the (+)-opiate, (+)-nordihydrocodeinone, partially attenuated the postural effects of (+)-pentazocine, despite its very low affinity for sigma 1, sigma 2, or opiate receptors. Taken together with previous studies, the results suggest that [3H](+)-pentazocine is a potent and selective probe for sigma 1 binding sites, but the in vivo effects of (+)-pentazocine cannot be fully attributed to actions through these sites. Some of the in vivo effects of (+)-pentazocine appear to involve other binding sites that are not detected under the conditions normally used in in vitro assays.