Gys1 Antisense Therapy Prevents Disease-Driving Aggregates and Epileptiform Discharges in a Lafora Disease Mouse Model

Patients with Lafora disease have a mutation in EPM2A or EPM2B, resulting in dysregulation of glycogen metabolism throughout the body and aberrant glycogen molecules that aggregate into Lafora bodies. Lafora bodies are particularly damaging in the brain, where the aggregation drives seizures with increasing severity and frequency, coupled with neurodegeneration. Previous work employed mouse genetic models to reduce glycogen synthesis by approximately 50%, and this strategy significantly reduced Lafora body formation and disease phenotypes. Therefore, an antisense oligonucleotide (ASO) was developed to reduce glycogen synthesis in the brain by targeting glycogen synthase 1 (Gys1). To test the distribution and efficacy of this drug, the Gys1-ASO was administered to Epm2b-/- mice via intracerebroventricular administration at 4, 7, and 10 months. The mice were then sacrificed at 13 months and their brains analyzed for Gys1 expression, glycogen aggregation, and neuronal excitability. The mice treated with Gys1-ASO exhibited decreased Gys1 protein levels, decreased glycogen aggregation, and reduced epileptiform discharges compared to untreated Epm2b-/- mice. This work provides proof of concept that a Gys1-ASO halts disease progression of EPM2B mutations of Lafora disease.

Tau-targeting antisense oligonucleotide MAPTRx in mild Alzheimer's disease: a phase 1b, randomized, placebo-controlled trial

Tau plays a key role in Alzheimer's disease (AD) pathophysiology, and accumulating evidence suggests that lowering tau may reduce this pathology. We sought to inhibit MAPT expression with a tau-targeting antisense oligonucleotide (MAPTRx) and reduce tau levels in patients with mild AD. A randomized, double-blind, placebo-controlled, multiple-ascending dose phase 1b trial evaluated the safety, pharmacokinetics and target engagement of MAPTRx. Four ascending dose cohorts were enrolled sequentially and randomized 3:1 to intrathecal bolus administrations of MAPTRx or placebo every 4 or 12 weeks during the 13-week treatment period, followed by a 23 week post-treatment period. The primary endpoint was safety. The secondary endpoint was MAPTRx pharmacokinetics in cerebrospinal fluid (CSF). The prespecified key exploratory outcome was CSF total-tau protein concentration. Forty-six patients enrolled in the trial, of whom 34 were randomized to MAPTRx and 12 to placebo. Adverse events were reported in 94% of MAPTRx-treated patients and 75% of placebo-treated patients; all were mild or moderate. No serious adverse events were reported in MAPTRx-treated patients. Dose-dependent reduction in the CSF total-tau concentration was observed with greater than 50% mean reduction from baseline at 24 weeks post-last dose in the 60 mg (four doses) and 115 mg (two doses) MAPTRx groups. Clinicaltrials.gov registration number: NCT03186989 .

Convective forces increase rostral delivery of intrathecal radiotracers and antisense oligonucleotides in the cynomolgus monkey nervous system

Background

The intrathecal (IT) dosing route introduces drugs directly into the CSF to bypass the blood–brain barrier and gain direct access to the CNS. We evaluated the use of convective forces acting on the cerebrospinal fluid as a means for increasing rostral delivery of IT dosed radioactive tracer molecules and antisense oligonucleotides (ASO) in the monkey CNS. We also measured the cerebral spinal fluid (CSF) volume in a group of cynomolgus monkeys.

Methods

There are three studies presented, in each of which cynomolgus monkeys were injected into the IT space with radioactive tracer molecules and/or ASO by lumbar puncture in either a low or high volume. The first study used the radioactive tracer ⁶⁴Cu-DOTA and PET imaging to evaluate the effect of the convective forces. The second study combined the injection of the radioactive tracer ^99mTc-DTPA and ASO, then used SPECT imaging and ex vivo tissue analysis of the effects of convective forces to bridge between the tracer and the ASO distributions. The third experiment evaluated the effects of different injection volumes on the distribution of an ASO. In the course of performing these studies we also measured the CSF volume in the subject monkeys by Magnetic Resonance Imaging.

Results

It was consistently found that larger bolus dose volumes produced greater rostral distribution along the neuraxis. Thoracic percussive treatment also increased rostral distribution of low volume injections. There was little added benefit on distribution by combining the thoracic percussive treatment with the high-volume injection. The CSF volume of the monkeys was found to be 11.9 ± 1.6 cm³.

Conclusions

These results indicate that increasing convective forces after IT injection increases distribution of molecules up the neuraxis. In particular, the use of high IT injection volumes will be useful to increase rostral CNS distribution of therapeutic ASOs for CNS diseases in the clinic.

Intrathecal administration of antisense oligonucleotide against p38α but not p38β MAP kinase isoform reduces neuropathic and postoperative pain and TLR4-induced pain in male mice

p38 mitogen-activated protein kinase (MAPK) consists of two major isoforms: p38α and p38β; however, it remains unclear which isoform is more important for chronic pain development. Recently, we developed potent, long-lasting, and p38 MAPK subtype-specific antisense oligonucleotides (ASOs). We examined the therapeutic effects of isoform-specific ASOs in several chronic pain models following single intrathecal injection (300 μg/10 μl) in CD1 mice. In the chronic constriction injury (CCI) model, p38α MAPK ASO, given on post-operative day 5, reduced CCI-induced mechanical allodynia in male but not female mice. In contrast, mechanical allodynia after CCI in both sexes was not affected by p38β MAPK ASO. Intrathecal injection of p38α or p38β ASO resulted in a partial reduction (≈ 50%) of spinal p38α or p38β mRNA level, respectively, in both sexes at two weeks. In contrast, intrathecal injection of the ASOs did not affect p38α and p38β MAPK mRNA levels in dorsal root ganglia. Intrathecal p38α ASO also reduced postoperative pain (mechanical and cold allodynia) in male mice after tibia fracture. However, intrathecal p38α ASO had no effect on mechanical allodynia in male mice after paclitaxel treatment. Intrathecal p38α MAPK ASO pre-treatment also prevented TLR4-mediated mechanical allodynia and downregulated levels of p38α MAPK and phosphorylated p38 MAPK following intrathecal treatment of lipopolysaccharide. In summary, our findings suggest that p38α MAPK is the major p38 MAPK isoform in the spinal cord and regulates chronic pain in a sex and model-dependent manner. Intrathecal p38α MAPK ASO may offer a new treatment for some chronic pain conditions.

Development of a simple, rapid, and robust intrathecal catheterization method in the rat

BACKGROUND

The blood brain barrier (BBB) is an impediment to the development of large and highly charged molecules as therapeutics for diseases and injuries of the central nervous system (CNS). Antisense oligonucleotides (ASOs) are large (6000-8000MW) and highly charged and therefore do not cross the BBB. A method of circumventing the blood brain barrier to test ASOs, and other non-BBB penetrant molecules, as CNS therapeutics is the direct administration of these molecules to the CNS tissue or cerebral spinal fluid.

NEW METHOD

We developed a rapid, simple and robust method for the intrathecal catheterization of rats to test putatively therapeutic antisense oligonucleotides. This method utilizes 23-gauge needles, simply constructed ½in. long 19-gauge guide cannulas and 8cm long plastic PE-10 sized catheters.

COMPARISON WITH EXISTING METHODS

Unlike the cisterna magna approach, this method uses a lumbar approach for intrathecal catheterization with the catheter residing entirely in the cauda equina space minimizing spinal cord compression. Readily available materials and only a few specialized pieces of equipment, which are easily manufactured, are used for this intrathecal catheterization method.

CONCLUSIONS

This method is easy to learn and has been taught to multiple in house surgeons, collaborators and contract laboratories. Greater than 90% catheterization success is routinely achieved with this method and as many as 100 catheters can be placed and test substance administered in one 6-h period. This method has allowed the pre-clinical testing of hundreds of ASOs as therapeutics for CNS indications.

Spinal release of tumour necrosis factor activates c-Jun N-terminal kinase and mediates inflammation-induced hypersensitivity

Background

Mounting evidence points to individual contributions of tumour necrosis factor-alpha (TNF) and the c-Jun N-terminal kinase (JNK) pathway to the induction and maintenance of various pain states. Here we explore the role of spinal TNF and JNK in carrageenan-induced hypersensitivity. As links between TNF and JNK have been demonstrated in vitro, we investigated if TNF regulates spinal JNK activity in vivo.

Methods

TNF levels in lumbar cerebrospinal fluid (CSF) were measured by enzyme-linked immunosorbent assay, spinal TNF gene expression by real-time polymerase chain reaction and TNF protein expression, JNK and c-Jun phosphorylation by western blotting. The role of spinal TNF and JNK in inflammation-induced mechanical and thermal hypersensitivity was assessed by injecting the TNF inhibitor etanercept and the JNK inhibitors SP600125 and JIP-1 intrathecally (i.t.). TNF-mediated regulation of JNK activity was examined by assessing the effect of i.t. etanercept on inflammation-induced spinal JNK activity.

Results

TNF levels were increased in CSF and spinal cord following carrageenan-induced inflammation. While JNK phosphorylation followed the same temporal pattern as TNF, c-jun was only activated at later time points. Intrathecal injection of TNF and JNK inhibitors attenuated carrageenan-induced mechanical and thermal hypersensitivity. TNF stimulation induced JNK phosphorylation in cultured spinal astrocytes and blocking the spinal actions of TNF in vivo by i.t. injection of etanercept reduced inflammation-induced spinal JNK activity.

Conclusions

Here we show that spinal JNK activity is dependent on TNF and that both TNF and the JNK signalling pathways modulate pain-like behaviour induced by peripheral inflammation.

Intrathecal neurosteroids and a neurosteroid antagonist: effects on inflammation-evoked thermal hyperalgesia and tactile allodynia

Neurosteroids regulate neuronal excitability though binding sites associated with the ionotropic γ-aminobutyric acid (GABAA) receptor. We sought to characterize the spinal analgesic actions in rats of two 5α-reduced neurosteroids, allopregnanolone and alphaxalone, on nociceptive processing and to determine whether a putative neurosteroid antagonist attenuates this effect: (3α,5α)-17-phenylandrost-16-en-3-ol (17PA). Intrathecal (IT) injection of allopregnanolone (1-30 μg/10 μL in 20% cyclodextrin) delivered through lumbar catheters produced a dose-dependent analgesia in rats as measured by thermal thresholds in the ipsilateral (inflamed by intraplantar carrageenan) and in the contralateral (un-inflamed paws). Similar observations were made with alphaxalone (30-60 μg in 20% cyclodextrin). Effective doses were not associated with suppressive effects on pinnae, blink or placing and stepping reflex. Effects of allopregnanolone (30 μg) on the normal and hyperalgesic paw were completely prevented by IT 17PA (30 μg). Reversal by IT 17PA of an equi-analgesic dose of alphaxalone occurred only at higher antagonist dosing. These results suggest that a spinal neurosteroid-binding site with which 17PA interacts may regulate spinal nociceptive processing in normal and inflamed tissue.

Spinal astrocytes produce and secrete dynorphin neuropeptides

Dynorphin peptide neurotransmitters (neuropeptides) have been implicated in spinal pain processing based on the observations that intrathecal delivery of dynorphin results in proalgesic effects and disruption of extracellular dynorphin activity (by antisera) prevents injury evoked hyperalgesia. However, the cellular source of secreted spinal dynorphin has been unknown. For this reason, this study investigated the expression and secretion of dynorphin-related neuropeptides from spinal astrocytes (rat) in primary culture. Dynorphin A (1-17), dynorphin B, and α-neoendorphin were found to be present in the astrocytes, illustrated by immunofluorescence confocal microscopy, in a discrete punctate pattern of cellular localization. Measurement of astrocyte cellular levels of these dynorphins by radioimmunoassays confirmed the expression of these three dynorphin-related neuropeptides. Notably, BzATP (3'-O-(4-benzoyl)benzoyl adenosine 5'-triphosphate) and KLA (di[3-deoxy-D-manno-octulosonyl]-lipid A) activation of purinergic and toll-like receptors, respectively, resulted in stimulated secretion of dynorphins A and B. However, α-neoendorphin secretion was not affected by BzATP or KLA. These findings suggest that dynorphins A and B undergo regulated secretion from spinal astrocytes. These findings also suggest that spinal astrocytes may provide secreted dynorphins that participate in spinal pain processing.

In vivo gene knockdown in rat dorsal root ganglia mediated by self-complementary adeno-associated virus serotype 5 following intrathecal delivery

We report here in adult rat viral vector mediate-gene knockdown in the primary sensory neurons and the associated cellular and behavior consequences. Self-complementary adeno-associated virus serotype 5 (AAV5) was constructed to express green fluorescent protein (GFP) and a small interfering RNA (siRNA) targeting mammalian target of rapamycin (mTOR). The AAV vectors were injected via an intrathecal catheter. We observed profound GFP expression in lumbar DRG neurons beginning at 2-week post-injection. Of those neurons, over 85% were large to medium-diameter and co-labeled with NF200, a marker for myelinated fibers. Western blotting of mTOR revealed an 80% reduction in the lumbar DRGs (L4–L6) of rats treated with the active siRNA vectors compared to the control siRNA vector. Gene knockdown became apparent as early as 7-day post-injection and lasted for at least 5 weeks. Importantly, mTOR knockdown occurred in large (NF200) and small-diameter neurons (nociceptors). The viral administration induced an increase of Iba1 immunoreactivity in the DRGs, which was likely attributed to the expression of GFP but not siRNA. Rats with mTOR knockdown in DRG neurons showed normal general behavior and unaltered responses to noxious stimuli. In conclusion, intrathecal AAV5 is a highly efficient vehicle to deliver siRNA and generate gene knockdown in DRG neurons. This will be valuable for both basic research and clinic intervention of diseases involving primary sensory neurons.

Acetaminophen prevents hyperalgesia in central pain cascade

Acetaminophen is an analgesic and antipyretic drug believed to exert its effect through interruption of nociceptive processing. In order to determine whether this effect is due to peripheral or central activity, we studied the efficacy of systemic (oral) and intrathecal (IT) application of acetaminophen in preventing the development of hyperalgesia induced through the direct activation of pro-algogenic spinal receptors. Spinal administration of substance P (SP, 30 nmol, IT) in rats produced a decreased thermal threshold, indicating centrally mediated hyperalgesia. Pretreatment of rats with oral acetaminophen (300 mg/kg), but not vehicle, significantly attenuated IT SP-induced hyperalgesia. Acetaminophen given IT also produced a dose-dependent (10-200 microg) antinociceptive effect. In addition, oral acetaminophen suppressed spinal PGE(2) release evoked by IT SP in an in vivo IT dialysis model. The ability of IT as well as oral acetaminophen to reverse this spinally initiated hyperalgesia emphasizes the likely central action and bioavailability of the systemically delivered drug. Jointly, these data argue for an important central antihyperalgesic action of acetaminophen.

Inhibition of spinal cytosolic phospholipase A(2) expression by an antisense oligonucleotide attenuates tissue injury-induced hyperalgesia

Activation of the spinal phospholipase A(2) (PLA(2)) -cyclooxygenase (COX) -prostaglandin signaling pathway is widely implicated in nociceptive processing. Although the role of spinal COX isoforms in pain signal transmission has been extensively characterized, our knowledge of PLA(2) enzymes in this cascade is limited. Among all PLA(2) groups, cytosolic calcium-dependent PLA(2) group IVA (cPLA(2)IVA) appears to be the predominant PLA(2) enzyme in the spinal cord. In the present study we sought to (i) characterize anatomical and cellular distribution and localization of cPLA(2)IVA in dorsal horn of rat spinal cord, (ii) verify efficacy and selectivity of intrathecal (IT) delivery of an antisense oligonucleotide (AS) targeting rat cPLA(2)IVA mRNA on spinal expression of this enzyme, and (iii) examine the effect of down-regulation of spinal cPLA(2)IVA on peripheral tissue injury-induced pain behavior. Here we demonstrate that cPLA(2)IVA is constitutively expressed in rat spinal cord, predominantly in dorsal horn neurons and oligodendrocytes but not in astrocytes or microglia. Intrathecal injection of AS significantly down-regulated both protein and gene expression of cPLA(2)IVA in rat spinal cord, while control missense oligonucleotide (MS) had no effect. Immunocytochemistry confirmed that the reduction occurred in neurons and oligodendrocytes. cPLA(2)IVA AS did not alter expression of several other PLA(2) isoforms, such as secretory PLA(2) (groups IIA and V) and calcium-independent PLA(2) (group VI), indicating that the AS was specific for cPLA(2)IVA. This selective knockdown of spinal cPLA(2)IVA did not change acute nociception (i.e. paw withdrawal thresholds to acute thermal stimuli and intradermal formalin-induced first phase flinching), however, it significantly attenuated formalin-induced hyperalgesia (i.e. second phase flinching behavior), which reflects spinal sensitization. Thus the present findings suggest that cPLA(2)IVA may specifically participate in spinal nociceptive processing.

Inhibition of spinal constitutive NOS-2 by 1400W attenuates tissue injury and inflammation-induced hyperalgesia and spinal p38 activation

Nitric oxide (NO) and its synthesizing enzymes, including NO synthase-2 (NOS-2, also called inducible NOS, iNOS), have been implicated in spinal nociception. 1400W is a highly selective NOS-2 inhibitor, as compared with either NOS-1 (neuronal NOS, nNOS) or NOS-3 (endothelial NOS). Here we examined the anti-nociceptive effects of intrathecal (IT) administration of 1400W in two experimental models of hyperalgesia (formalin and carrageenan models), in addition to the effect of 1400W on stimulation-induced activation of spinal p38 mitogen-activated protein kinase (p38). IT treatment of rats with 1400W produced a dose-dependent inhibition of paw formalin-induced phase II flinches, and attenuated carrageenan-induced thermal hyperalgesia. In contrast, IT injection of a selective inhibitor of NOS-1, nNOS inhibitor-I, had no effect in either model. Furthermore, 1400W at a dose that suppressed formalin-induced flinching behavior also blocked formalin-evoked p38 phosphorylation (activation) in the spinal cord, while nNOS inhibitor-I displayed no activity. The prompt effects of IT 1400W suggest involvement of constitutively expressed NOS-2 in spinal nociception. The NOS-2 protein in rat spinal cords was undetectable by Western blotting. However, when the protein was immunoprecipitated prior to Western blotting, NOS-2-immunoreactive bands were detected in the tissues, including naïve spinal cords. The presence of constitutive spinal NOS-2 was further confirmed by reverse transcriptase-polymerase chain reaction. Taken together, the present studies suggest that constitutively expressed spinal NOS-2 mediates tissue injury and inflammation-induced hyperalgesia, and that activation of p38 is one of the downstream factors in NO-mediated signaling in the initial processing of spinal nociception.

Descending serotonergic facilitation of spinal ERK activation and pain behavior

Serotonin (5-HT) derived from bulbo-spinal projection is released by nociceptive input into the spinal dorsal horn. Here we report that formalin injection in the paw produced pain behavior (flinching) and phosphorylation of spinal ERK1/2 (P-ERK1/2, indicating activation) in rats. Depletion of spinal 5-HT by intrathecal (IT) 5,7-DHT, a serotonergic neurotoxin, profoundly reduced formalin evoked flinching and the increase in P-ERK1/2. Ondansetron (a 5-HT3 receptor antagonist) at IT doses that inhibited flinching also attenuated spinal ERK activation. These findings reveal that primary afferent-evoked activation of spinal ERK requires the input from an excitatory 5-HT descending pathway.

Intrathecal minocycline attenuates peripheral inflammation-induced hyperalgesia by inhibiting p38 MAPK in spinal microglia

Activation of p38 mitogen-activated protein kinase (p38) in spinal microglia is implicated in spinal nociceptive processing. Minocycline, a tetracycline derivative, displays selective inhibition of microglial activation, a function that is distinct from its antibiotic activity. In the present study we examined antinociceptive effects of intrathecal (IT) administration of minocycline in experimental models of inflammation-evoked hyperalgesia in addition to the effect of minocycline on stimulation-induced activation of p38 in spinal microglia. Intrathecal minocycline produced a dose-dependent reduction of formalin-evoked second-phase flinching behaviour in rats, and prevented thermal hyperalgesia induced by carrageenan injection into the paw. In contrast, systemic delivery (intraperitoneally) of minocycline inhibited the first but not the second phase of formalin-induced flinching, and it had no effect on carrageenan-induced hyperalgesia. Centrally mediated hyperalgesia induced by IT delivery of N-methyl-d-aspartate was completely blocked by IT minocycline. An increase in phosphorylation (activation) of p38 (P-p38) was observed in the dorsal spinal cord after carrageenan paw injection, assessed by both Western blotting and immunohistochemistry. The increased P-p38 immunoreactivity was seen primarily in microglia but also in a small population of neurons. Minocycline, at the IT dose that blocked carrageenan-induced hyperalgesia, also attenuated the increased P-p38 in microglia. In addition, minocycline suppressed lipopolysaccharide-evoked P-p38 in cultured spinal microglial cells. Taken together, these findings show that minocycline given IT produces a potent and consistent antinociception in models of tissue injury and inflammation-evoked pain, and they provide strong support for the idea that this effect is mediated by direct inhibition of spinal microglia and subsequent activation of p38 in these cells.

Systemic and Intrathecal Effects of a Novel Series of Phospholipase A2 Inhibitors on Hyperalgesia and Spinal Prostaglandin E2 Release

Phospholipase A(2) (PLA(2)) forms are expressed in spinal cord, and inhibiting spinal PLA(2) induces a potent antihyperalgesia. Here, we examined the antihyperalgesic effects after systemic and i.t. delivery of four compounds constructed with a common motif consisting of a 2-oxoamide with a hydrocarbon tail and a four-carbon tether. These molecules were characterized for their ability to block group IVA calcium-dependent PLA(2) (cPLA(2)) and group VIA calcium-independent PLA(2) (iPLA(2)) in inhibition assays using human recombinant enzyme. The rank ordering of potency in blocking group IVA cPLA(2) was AX048 (ethyl 4-[(2-oxohexadecanoyl)amino]butanoate), AX006 (4-[(2-oxohexadecanoyl)amino]butanoic acid), and AX057 (tert-butyl 4-[(2-oxohexadecanoyl)amino]butanoate) > AX010 (methyl 4-[(2-oxohexadecanoyl)amino]butanoate) and for inhibiting group VIA iPLA(2) was AX048, AX057 > AX006, and AX010. No agent altered recombinant cyclooxygenase activity. In vivo, i.t. (30 mug) and systemic (0.2-3 mg/kg i.p.) AX048 blocked carrageenan hyperalgesia and after systemic delivery in a model of spinally mediated hyperalgesia induced by i.t. substance P (SP). The other agents were without activity. In rats prepared with lumbar i.t. loop dialysis catheters, SP evoked spinal prostaglandin E(2) (PGE(2)) release. AX048 alone inhibited PGE(2) release. Intrathecal SR141617, a cannabinoid CB1 inhibitor at doses that blocked the effects of i.t. anandamide had no effect upon i.t. AX048. These results suggest that AX048 is the first systemically bioavailable compound with a significant affinity for group IVA cPLA(2), which produces a potent antihyperalgesia. The other agents, although demonstrating enzymatic activity in cell-free assays, appear unable to gain access to the intracellular PLA(2) toward which their action is targeted.

Mechanisms of antinociception of spinal galanin: how does galanin inhibit spinal sensitization?

Galanin by a spinal action has been shown to have an antihyperalgesic action. Thus, in rats with lumbar intrathecal (IT) catheters, the thermal hyperalgesia evoked by carrageenan paw injection was blocked by IT delivery of galanin(1-29) (Gal(1-29)) and galanin(2-11) (Gal(2-11)) with the rank order of activity being Gal(1-29)>Gal(2-11). We sought to determine whether this spinal action reflects an effect upon afferent transmitter release, e.g., substance P (SP), and/or on secondary neurons, e.g., signaling postsynaptic to neurokinin 1 (NK1) receptor activation. To address the question on afferent release, we investigated the effect of IT administration of galanin on tissue injury-induced spinal NK1 internalization (an indicator of SP release). Noxious stimulation (paw compression) produced an increase in NK1 internalization in dorsal horn lamina I. IT pretreatment of rats with Gal(1-29) and Gal(2-11) significantly attenuated the evoked NK1 internalization, with the rank order of activity being Gal(1-29)>Gal(2-11)>saline. To address the question of postsynaptic action, we examined the effects of IT galanin upon IT SP-induced thermal hyperalgesia and spinal PGE2 release. Application of SP (30 nmol) directly to spinal cord led to a decrease in thermal thresholds and a profound increase in PGE(2) concentration in spinal dialysates. Both phenomena were reversed by Gal(1-29) and Gal(2-11) (10nmol, IT). These findings suggest that the antihyperalgesic effect of spinal galanin is due to its action on sites both presynaptic (inhibition of SP release) and postsynaptic (blockade of SP-evoked hyperalgesia and PGE2 production) to the primary afferents.

Spinal p38beta isoform mediates tissue injury-induced hyperalgesia and spinal sensitization

Antagonist studies show that spinal p38 mitogen-activated protein kinase plays a crucial role in spinal sensitization. However, there are two p38 isoforms found in spinal cord and the relative contribution of these two to hyperalgesia is not known. Here we demonstrate that the isoforms are distinctly expressed in spinal dorsal horn: p38alpha in neurons and p38beta in microglia. In lieu of isoform selective inhibitors, we examined the functional role of these two individual isoforms in nociception by using intrathecal isoform-specific antisense oligonucleotides to selectively block the expression of the respective isoform. In these rats, down-regulation of spinal p38beta, but not p38alpha, prevented nocifensive flinching evoked by intraplantar injection of formalin and hyperalgesia induced by activation of spinal neurokinin-1 receptors through intrathecal injection of substance P. Both intraplantar formalin and intrathecal substance P produced an increase in spinal p38 phosphorylation and this phosphorylation (activation) was prevented when spinal p38beta, but not p38alpha, was down-regulated. Thus, spinal p38beta, probably in microglia, plays a significant role in spinal nociceptive processing and represents a potential target for pain therapy.

Galanin acts at GalR1 receptors in spinal antinociception: synergy with morphine and AP-5

The neuropeptide galanin (Gal) and its receptors (GalR1, GalR2, and GalR3) are expressed in spinal cord. We have characterized the pharmacology of the antinociceptive effects of intrathecally (i.t.) administered galanin and its analogs in the formalin test in rats, using an automated flinch detection system. Intrathecal injection of rat galanin (Gal(1-29)) or human galanin (Gal(1-30)) produced a dose-dependent inhibition of formalin-evoked flinching in phase 2, but not in phase 1. Relative potency of galanin homologs is Gal(1-29) >or= Gal(1-30) > galanin-like peptide(1-24) >or= Gal(2-11) = Gal (3-29) (an inactive analog). Galanin(1-29) and Gal(1-30) are both high-affinity agonists to GalR1/R2, whereas Gal(2-11) is a GalR2 receptor agonist. Our data suggest that i.t. galanin-produced antinociception is mediated by activation of GalR1 receptors. When comparing antinociceptive effects of i.t. Gal(1-29) to morphine and to 2-amino-5-phosphonopentanoic acid (AP-5, an N-methyl-d-aspartate antagonist), Gal(1-29) is of intermediate potency between these two analgesic agents based on the ED(50) values. An isobolographic analysis showed synergy between Gal(1-29) and morphine and between Gal(1-29) and AP-5 on the second phase. Fixed ratio dose combinations of morphine and Gal(1-29), or AP-5 and Gal(1-29) produced significantly greater antinociception than predicted from simple additivity. In summary, the present findings reveal that 1) spinal galanin produces a reliable inhibition of formalin-induced facilitated nociceptive processing, an effect possibly mediated by GalR1 receptors; and 2) galanin potentiates i.t. morphine and AP-5-induced antinociception.

Intrathecal vincristine: an analysis of reasons for recurrent fatal chemotherapeutic error with recommendations for prevention

PURPOSE

Accidental intrathecal vincristine instillation is usually a fatal error. The authors report an analysis of a patient and suggest means with which to reduce such errors.

PATIENTS AND METHODS

A 7-year-old girl with recurrent acute lymphoblastic leukemia was inadvertently injected intrathecally with 1.5 mg vincristine. A detailed analysis of the events leading to this error and a review of all reported cases in the English literature were undertaken.

RESULTS

Reasons for errors reported by us and other institutions included mistaking vincristine for an intended intrathecal drug, assuming vincristine was an additional drug to be injected, not checking physician orders, mistaken route of administration, and mislabeling of syringes.

CONCLUSION

Intrathecal injection of vincristine may be the end-result of a series of systems errors. Protocol recommendations to reduce the likelihood of this error are presented.

Nurse educator performance standards

In this article, the authors highlight the process by which one staff education department developed performance standards. These standards facilitate orientation of new educators, assist with the planning of developmental goals, and guide the evaluation process. This process can serve as a prototype for nurse educators faced with the challenge of developing performance standards.

Parkinson's disease. Quality of life issues

PD affects many dimensions of quality of life. This article has identified motor and nonmotor features of PD that are directly related to a patient's quality of life. Medication therapy can help to ameliorate some of the symptoms, yet side effects can be as disabling as the symptoms of PD. Nursing care should include assessment, intervention, and evaluation of both physical and psychosocial aspects of care for patients with PD to assist them in achieving maximum functioning.

Development of 2,3-dihydro-6-(3-phenoxypropyl)-2-(2-phenylethyl)-5-benzofuranol (L-670,630) as a potent and orally active inhibitor of 5-lipoxygenase

Leukotrienes are potent biological mediators of allergic and inflammatory diseases and are derived from arachidonic acid through the action of the 5-lipoxygenase. In this study, the syntheses and comparative biological activities of three series of 2,3-dihydro-2,6-disubstituted-5-benzofuranols with various substituents on position 3 are described. Compounds from each series were evaluated for their ability to inhibit the production of leukotriene B4 (LTB4) in human peripheral blood polymorphonuclear (PMN) leukocytes and the 5-lipoxygenase reaction in cell-free preparations from rat PMN leukocytes. The structure-activity relationships of each series in vitro and in vivo are presented. The bioavailability, metabolism, and toxicity profile of each series are discussed. The series with no substituent at position 3 was the most potent and among the compounds in that series 2,3-dihydro-6-(3-phenoxypropyl)-2-(2-phenylethyl)-5-benzofuranol (46, L-670,630) was chosen for further development.

Depression in Parkinson's disease

Approximately 50% of patients with Parkinson's disease experience clinical depression. Neurotransmitter deficits in depression and Parkinson's disease suggest a common lesion may be responsible for this high incidence. In addition to similar psychological profiles, the clinical features of Parkinson's disease and depression likewise overlap making the distinction difficult. Differentiating these two diseases is very important, as each is treatable. The neuroscience nurse is in a unique position to evaluate the patient with Parkinson's disease for signs and symptoms of depression.

The in vivo production of peptide leukotrienes after pulmonary anaphylaxis in the rat

Inbred hyper-reactive rats, actively sensitized to OVA, were anesthetized, cannulated, and ventilated with room air. Tracheal instillation of Ag (OVA) resulted in an elevation of airways pressure (14.4 +/- 0.6 cm H2O). Measurement of biliary peptide leukotriene levels before and after Ag challenge using reverse phase HPLC and RIA techniques showed significant elevations in leukotriene (LT) levels, the amounts released being LTC4 (3.65 +/- 0.78), LTD4 (2.8 +/- 1.11), and N-Ac LTE4 (3.87 +/- 1.15) expressed as ng/100 g of body weight, n = 13. Identification of these metabolites were confirmed by HPLC/RIA techniques and LTC4 was further characterized by UV spectroscopy and its enzymatic conversion by gamma-glutamyl transpeptidase to LTD4. [3H]LTC4 (16 ng) administration by tracheal instillation resulted in a 31.4 +/- 4.3% recovery of radioactivity through the bile over 4 h (n = 3) with the major identified metabolite being N-Ac LTE4. [3H]LTC4 (16 ng) plus synthetic LTC4 (5 micrograms) showed a 30.8 +/- 3.1% recovery through the bile after tracheal instillation (3-h collection, n = 4) with significant amounts of LTC4 as well as N-Ac LTE4 present. [3H]LTC4 administration by the portal vein resulted in a 37.4 +/- 8.8% biliary recovery over 60 min (n = 6), the metabolites present in the bile being LTC4, LTD4, LTE4, and N-Ac LTE4. Pretreatment with the 5-lipoxygenase inhibitor L-656,224 (15 mg/kg, 3.5 h pre-p.o.) before Ag challenge resulted in a significant inhibition (greater than 90%, p less than 0.05) of biliary leukotriene levels in this model. Our study demonstrates that peptide leukotrienes are produced in the anesthetized rat after pulmonary anaphylaxis and that biliary leukotriene measurement is suitable for showing the biochemical efficacy of leukotriene inhibitors in vivo. In vivo tracer experiments suggest that the biliary metabolic profile of the peptide leukotrienes is dependent on the site and levels of release as well as the efficiency of the vascular clearance of the various metabolites.

The in vivo production of peptide leukotrienes after pulmonary anaphylaxis in the rat

Inbred hyper-reactive rats, actively sensitized to OVA, were anesthetized, cannulated, and ventilated with room air. Tracheal instillation of Ag (OVA) resulted in an elevation of airways pressure (14.4 +/- 0.6 cm H2O). Measurement of biliary peptide leukotriene levels before and after Ag challenge using reverse phase HPLC and RIA techniques showed significant elevations in leukotriene (LT) levels, the amounts released being LTC4 (3.65 +/- 0.78), LTD4 (2.8 +/- 1.11), and N-Ac LTE4 (3.87 +/- 1.15) expressed as ng/100 g of body weight, n = 13. Identification of these metabolites were confirmed by HPLC/RIA techniques and LTC4 was further characterized by UV spectroscopy and its enzymatic conversion by gamma-glutamyl transpeptidase to LTD4. [3H]LTC4 (16 ng) administration by tracheal instillation resulted in a 31.4 +/- 4.3% recovery of radioactivity through the bile over 4 h (n = 3) with the major identified metabolite being N-Ac LTE4. [3H]LTC4 (16 ng) plus synthetic LTC4 (5 micrograms) showed a 30.8 +/- 3.1% recovery through the bile after tracheal instillation (3-h collection, n = 4) with significant amounts of LTC4 as well as N-Ac LTE4 present. [3H]LTC4 administration by the portal vein resulted in a 37.4 +/- 8.8% biliary recovery over 60 min (n = 6), the metabolites present in the bile being LTC4, LTD4, LTE4, and N-Ac LTE4. Pretreatment with the 5-lipoxygenase inhibitor L-656,224 (15 mg/kg, 3.5 h pre-p.o.) before Ag challenge resulted in a significant inhibition (greater than 90%, p less than 0.05) of biliary leukotriene levels in this model. Our study demonstrates that peptide leukotrienes are produced in the anesthetized rat after pulmonary anaphylaxis and that biliary leukotriene measurement is suitable for showing the biochemical efficacy of leukotriene inhibitors in vivo. In vivo tracer experiments suggest that the biliary metabolic profile of the peptide leukotrienes is dependent on the site and levels of release as well as the efficiency of the vascular clearance of the various metabolites.

Evidence of in-vivo omega-oxidation of peptide leukotrienes in the rat: biliary excretion of 20-CO2H N-acetyl LTE4

In a previous study in our laboratory it was observed that after [3H] LTC4 administration (luCi/kg i.v.) to the anesthetized rat, significant amounts of injected radioactivity (approximately 25%) were associated with previously unidentified biliary polar metabolite(s). In the present study we describe the isolation and characterization of the predominant polar metabolite. Rats were injected with synthetic LTC4 (20 microgram/kg i.v.) and bile collected over 30 min. After extraction and purification (2 step RP-HPLC procedure), the retention time of the metabolite was compared (plus coinjections) and found to be identical with synthetic 20-CO2H N-Ac LTE4 in two RP-HPLC systems. Also, the UV spectrum of the biologically derived metabolite was compared and found identical to the synthetic material, giving a characteristic conjugated triene absorption in the UV with a max of 281 nm and shoulders at 270 and 290 nm. Further, the trimethyl ester derivative of the metabolite showed identical chromatographic behaviors in 2 reverse and 2 normal phase HPLC systems compared with synthetic 20-CO2H N-Ac LTE4 trimethyl ester. We conclude omega-oxidation of peptide leukotrienes occurs in the rat and that 20-CO2H N-Ac LTE4 is an in vivo product of LTC4 metabolism.

Metabolism and excretion of peptide leukotrienes in the anesthetized rat

The metabolism and excretion of the peptide leukotrienes C4, D4, E4 and N-acetylleukotriene E4 have been studied in the anesthetized rat. The intravenous administration of [3H]leukotriene C4 (2.6 X 10(-11) mol/kg) showed a rapid clearance of radioactivity from the blood and a time-related biliary excretion, recovering 69 +/- 1.6% (n = 6) over 60 min. Less than 1% of total radioactivity was recovered in the urine over the same time period. Similarly, the intravenous administration of [3H]leukotriene D4 (2.5 X 10(-11) mol/kg), [3H]leukotriene E4 (2.5 X 10(-11) mol/kg) and N-acetyl[3H]leukotriene E4 (2.1 X 10(-11) mol/kg) showed a 62 +/- 7.5% (n = 4), 52 +/- 1.5% (n = 4) and 37 +/- 4.6% (n = 5) biliary recovery of radioactivity, respectively, after 60 min. Examination of bile identified leukotriene D4 and N-acetylleukotriene E4 as the main products, although substantial radioactivity, which probably represents unidentified polar products, was present at the solvent fronts of the reverse-phase HPLC. Time course studies indicated a relatively rapid conversion of leukotriene C4 to leukotriene D4, while leukotriene D4 metabolism appeared to be much slower. Leukotriene E4 was a minor product, suggesting that the N-acetylation process is rapid. Incubation of [3H]leukotriene C4 in rat plasma and whole blood in vitro resulted in a slow conversion of leukotriene C4 to leukotriene D4 and leukotriene E4 only. These data suggest that the majority of the leukotriene metabolism and excretion in vivo in the anesthetized rat occurs predominantly in the hepatic system. We conclude that this model is suitable for the measurement of in vivo production of peptide leukotrienes.

Stereochemical requirements for substrate specificity of LTB4 20-hydroxylase

LTB4 20-hydroxylase (P-450LTB) is the cytochrome P-450 in the microsomes of human polymorphonuclear leukocytes that catalyzes the omega-oxidation of leukotriene B4 (LTB4) to 20-OH LTB4. The activity of P-450LTB for LTB4 compared to isomers and analogs of LTB4 at a concentration of 0.3 microM revealed a preference of P-450LTB for both the triene bond configuration of LTB4 and for the chirality of the 5S and 12R hydroxyl groups. 15S-Hydroxyeicosatetraenoic acid, 8(R/S), 15S-dihydroxy-5-cis-9,11,13-trans-eicosatetraenoic acid, 8R,15S-dihydroxy-5,13-cis-9,11-trans-eicosatetraenoic acid, and 5S,15S-dihydroxy-6,13-trans-8,11-cis-eicosatetraenoic acid were each not subject to omega-oxidation, indicating a negative effect of the presence of a 15-hydroxyl group on substrate recognition. At a concentration of 1.5 microM, 12R- and 12S-hydroxyeicosatetraenoic acid were converted to their respective 20-OH derivatives at rates that were 34.2 +/- 11.6% (mean +/- S.D., n = 3) and 3.5 +/- 4.3% (mean +/- S.D., n = 4), respectively, of that of LTB4 to 20-OH LTB4, further indicating that P-450LTB can distinguish the chirality of the 12-hydroxyl group. The lower Km of LTB4 (2.0 microM), as compared to those of its 6-trans-12-epi isomer (3.8 microM) and 5-epi-LTB4 (6.6 microM) confirmed the preference of P-450LTB for the specific triene bond structure of LTB4 and its preference for the chirality of the hydroxyl groups of LTB4 within this structurally related class of molecules. At equal 1.5-microM concentrations, LTB4 completely inhibited the omega-oxidation of all other substrates and partially suppressed that of leukotriene B5, consistent with the lower Km of LTB4 and indicating that P-450LTB catalyzed the omega-oxidation of all substrates. Thus, P-450LTB is a novel cytochrome P-450 of human polymorphonuclear leukocytes with substrate recognition determined by the triene bond configuration and the chirality of the hydroxyl groups.

The synthesis of N-acetyl-leukotriene E4 and its effects on cardiovascular and respiratory function of the anesthetized pig

The effects of the putative biliary metabolite of the peptido-leukotrienes, N-acetyl-leukotriene (LT) E4 has been investigated in the anesthetized pig. Intravenous bolus doses of synthetic N-acetyl-LTE4 produced minimal respiratory and cardiovascular actions in the pig. N-acetyl-LTE4 was approximately 100-fold less active than LTC4. The actions of N-acetyl-LTE4 were not blocked by pretreatment of the animals with indomethacin (5 mg/kg iv) or with a selective LTD4 antagonist L-649,923 (5 mg/kg plus 2 mg/kg/hr iv). In summary, N-acetyl-LTE4 exerts weak actions in the pig which is consistent with the acetylation process being a mechanism of detoxification.

Actions of synthetic leukotrienes on platelets and blood vessels in the anesthetised pig: the release of a platelet derived vasodilator

The actions of leukotrienes (LT's) C4, D4, E4 and F4 have been investigated in the perfused hind-limb of the anesthetized pig. In the blood perfused hind limb LTC4, D4 and E4 increased the perfusion pressure in a dose-dependent fashion whereas LTF4 decreased perfusion pressure. In the Tyrode perfused hind limb all LT's increased perfusion pressure (rank order potency LTC4 = LTD4 much greater than LTF4). The actions of LTF4 were not affected by a wide variety of pharmacological treatments, including indomethacin, methysergide and FPL-55712. The LT's aggregated porcine platelets (rank order potency LTC4 greater than LTF4 greater than LTD4) and induced the release of a platelet-derived vasodilatory mediator. The results provide pharmacological evidence of specific leukotriene receptors in vivo and that leukotrienes can independently modulate blood flow. These data suggest that important interactions may occur between platelets, the arachidonate lipoxygenase products and platelet-derived substances in response to inflammatory stimuli in the cardiovascular system.

Biological activities of isomers of 8,15-dihydroxyeicosatetraenoic acid

Chemically synthesized 8(S), 15(S)-dihydroxy-5,11-cis-9, 13-trans-eicosatetraenoic acid and 8(R), 15(S)-dihydroxy-5,11-cis-9,13-trans-eicosatetraenoic acid were inactive, in comparison to leukotriene B4, in a human polymorphonuclear leukocyte chemokinetic assay and a rat polymorphonuclear leukocyte aggregation assay.

Clinical study of mianserin, imipramine and placebo in depression: blood level and MHPG correlations

1. The clinical efficacy of mianserin, a tetracyclic compound, was compared with imipramine and placebo in 47 hospitalized depressed patients. 2. The clinical ratings showed that the three treatment groups improved equivalently during hospitalization. 3. Plasma levels of mianserin correlated with changes in the Hamilton Rating Scale for depression, total score and two of its factors (anxiety/somatization, and retardation) and the item 'late insomnia'. 4. Drowsiness was a more frequent side-effect among mianserin patients on day 4; no other side-effect distinguished the treatments. 5. No relationship between MHPG levels and treatment or treatment outcome were observed.