Economic evaluations of fluticasone-propionate/salmeterol combination therapy for chronic obstructive pulmonary disease: a review of published studies

This review identifies and evaluates the comprehensive reporting of peer-reviewed economic evaluations of the effectiveness of fluticasone-propionate/salmeterol combination (FSC) therapy for maintenance treatment of chronic obstructive pulmonary disease (COPD). Economic evaluations were included if published in English since 2003. Evaluation categories included in the review were cost-effectiveness, cost-utility, and cost-consequence analyses. FSC is cost-effective in comparison to short-acting bronchodilators (SABDs). Cost and outcome differences between FSC and other long-acting therapies were modest. Studies exhibited large variations in populations, designs and environment, limiting the ability to draw conclusions. Many new maintenance treatments for COPD have been approved since 2010. Most have yet to be compared to older treatments like FSC. Evaluations are needed that consider costs and outcomes from a societal perspective (e.g., patients' ability to keep working) and evaluations that include subgroup analyses to investigate differential impacts according to clusters of patient characteristics.

Biocompatibility of single-walled carbon nanotube composites for bone regeneration

OBJECTIVES

The purpose of this study was to evaluate in vivo biocompatibility of novel single-walled carbon nanotubes (SWCNT)/poly(lactic-co-glycolic acid) (PLAGA) composites for applications in bone and tissue regeneration.

METHODS

A total of 60 Sprague-Dawley rats (125 g to 149 g) were implanted subcutaneously with SWCNT/PLAGA composites (10 mg SWCNT and 1gm PLAGA 12 mm diameter two-dimensional disks), and at two, four, eight and 12 weeks post-implantation were compared with control (Sham) and PLAGA (five rats per group/point in time). Rats were observed for signs of morbidity, overt toxicity, weight gain and food consumption, while haematology, urinalysis and histopathology were completed when the animals were killed.

RESULTS

No mortality and clinical signs were observed. All groups showed consistent weight gain, and the rate of gain for each group was similar. All groups exhibited a similar pattern for food consumption. No difference in urinalysis, haematology, and absolute and relative organ weight was observed. A mild to moderate increase in the summary toxicity (sumtox) score was observed for PLAGA and SWCNT/PLAGA implanted animals, whereas the control animals did not show any response. Both PLAGA and SWCNT/PLAGA showed a significantly higher sumtox score compared with the control group at all time intervals. However, there was no significant difference between PLAGA and SWCNT/PLAGA groups.

CONCLUSIONS

Our results demonstrate that SWCNT/PLAGA composites exhibited in vivo biocompatibility similar to the Food and Drug Administration approved biocompatible polymer, PLAGA, over a period of 12 weeks. These results showed potential of SWCNT/PLAGA composites for bone regeneration as the low percentage of SWCNT did not elicit a localised or general overt toxicity. Following the 12-week exposure, the material was considered to have an acceptable biocompatibility to warrant further long-term and more invasive in vivo studies. Cite this article: Bone Joint Res 2015;4:70-7.

Effects of 5-hydroxytryptamine applied into nucleus raphe magnus on nociceptive thresholds and neuronal firing rate

The effect of iontophoretically applied 5-hydroxytryptamine on neurones in nucleus raphe magnus, and the effect of microinjection of 5-hydroxytryptamine into nucleus raphe magnus on nociceptive thresholds were examined in the rat. Iontophoretically applied 5-hydroxytryptamine excited 66% and inhibited 6% of the neurones encountered in the nucleus raphe magnus. The excitatory response to 5-hydroxytryptamine was reduced by the putative serotonergic antagonist cinanserin in 21 of 24 cases. In 12 of these neurones the responses to iontophoretically applied glutamate were also examined. In 11 of the 12 studies the responses to glutamate were reduced by cinanserin. Microinjection of 5 microg of 5-hydroxytryptamine into the nucleus raphe magnus produced analgesia as assessed by the tail-flick response to noxious heat stimulation, but no analgesia as assessed by the paw withdrawal response to pressure. Microinjection of 5 microg of 5-hydroxytryptamine into the adjacent nucleus reticularis paragigantocellularis had no analgesic effect in either test. These results indicate that 5-hydroxytryptamine mainly excites neurones in nucleus raphe magnus and that 5-hydroxytryptamine has an action on neurones in nucleus raphe magnus which modulate the nociceptive threshold.

MUC1 as a discriminator between endometrium from fertile and infertile patients with PCOS and endometriosis

CONTEXT

Endometrium of fertile women expresses progesterone-regulated Mucin 1 (MUC1) that carries selectin ligands recognized by the human blastocyst. Altered MUC1 expression at the time of implantation may contribute to endometrial infertility.

OBJECTIVE

The aim was to assess the expression of MUC1 in the endometrium from polycystic ovary syndrome (PCOS), endometriosis, and fertile women in comparison with other hormone-regulated proteins [hydroxysteroid dehydrogenase (HSD) 1, HSD2, estrogen receptor (ER) and progesterone receptor (PR)].

DESIGN AND PATIENTS

Endometrial samples were obtained from 33 fertile patients, 26 ovulatory PCOS patients, 15 anovulatory PCOS patients, and 25 endometriosis patients.

MAIN OUTCOME MEASURE

Immunohistochemistry assessed the expression of MUC1 subunits ER, PR, HSD1, and HSD2 in endometrial epithelium. Endometrial MUC1 expression was quantified by immunoblots and RT-PCR. HSD1 and HSD2 expression was assayed by RT-PCR.

RESULTS

MUC1ND expression was significantly higher in ovulatory PCOS than in fertile and anovulatory PCOS patients, even after progesterone stimulation. MUC1ND and -CD expression was lower in anovulatory PCOS than in fertile patients. Only MUC1CD expression was lower in endometriosis patients. Endometrial ER expression was significantly higher in PCOS and endometriosis patients, whereas PR expression was significantly higher in PCOS than in fertile patients. The expression of HSD1 was significantly higher in anovulatory PCOS than in fertile patients. Expression of HSD2 was significantly higher in PCOS patients and lower in endometriosis patients.

CONCLUSION

Expression of MUC1 subunits in the infertile endometrium is significantly different from fertile and appears to be a component of altered gene expression that potentially contributes to endometrial insufficiency.

Toll-like receptor 4 mediates the response of epithelial and stromal cells to lipopolysaccharide in the endometrium

BACKGROUND

Ascending infections of the female genital tract with bacteria causes pelvic inflammatory disease (PID), preterm labour and infertility. Lipopolysaccharide (LPS) is the main component of the cell wall of Gram-negative bacteria. Innate immunity relies on the detection of LPS by Toll-like receptor 4 (TLR4) on host cells. Binding of LPS to TLR4 on immune cells stimulates secretion of pro-inflammatory cytokines such as IL-6, chemokines such as CXCL1 and CCL20, and prostaglandin E(2). The present study tested the hypothesis that TLR4 on endometrial epithelial and stromal cells is essential for the innate immune response to LPS in the female genital tract.

METHODOLOGY/PRINCIPAL FINDINGS

Wild type (WT) mice expressed TLR4 in the endometrium. Intrauterine infusion of purified LPS caused pelvic inflammatory disease, with accumulation of granulocytes throughout the endometrium of WT but not Tlr4(-/-) mice. Intra-peritoneal infusion of LPS did not cause PID in WT or Tlr4(-/-) mice, indicating the importance of TLR4 in the endometrium for the detection of LPS in the female genital tract. Stromal and epithelial cells isolated from the endometrium of WT but not Tlr4(-/-) mice, secreted IL-6, CXCL1, CCL20 and prostaglandin E(2) in response to LPS, in a concentration and time dependent manner. Co-culture of combinations of stromal and epithelial cells from WT and Tlr4(-/-) mice provided little evidence of stromal-epithelial interactions in the response to LPS.

CONCLUSIONS/SIGNIFICANCE

The innate immune response to LPS in the female genital tract is dependent on TLR4 on the epithelial and stromal cells of the endometrium.

Specific strains of Escherichia coli are pathogenic for the endometrium of cattle and cause pelvic inflammatory disease in cattle and mice

Background

Escherichia coli are widespread in the environment and pathogenic strains cause diseases of mucosal surfaces including the female genital tract. Pelvic inflammatory disease (PID; metritis) or endometritis affects ∼40% of cattle after parturition. We tested the expectation that multiple genetically diverse E. coli from the environment opportunistically contaminate the uterine lumen after parturition to establish PID.

Methodology/Principal Findings

Distinct clonal groups of E. coli were identified by Random Amplification of Polymorphic DNA (RAPD) and Multilocus sequence typing (MLST) from animals with uterine disease and these differed from known diarrhoeic or extra-intestinal pathogenic E. coli. The endometrial pathogenic E. coli (EnPEC) were more adherent and invasive for endometrial epithelial and stromal cells, compared with E. coli isolated from the uterus of clinically unaffected animals. The endometrial epithelial and stromal cells produced more prostaglandin E₂ and interleukin-8 in response to lipopolysaccharide (LPS) purified from EnPEC compared with non-pathogenic E. coli. The EnPEC or their LPS also caused PID when infused into the uterus of mice with accumulation of neutrophils and macrophages in the endometrium. Infusion of EnPEC was only associated with bacterial invasion of the endometrium and myometrium. Despite their ability to invade cultured cells, elicit host cell responses and establish PID, EnPEC lacked sixteen genes commonly associated with adhesion and invasion by enteric or extraintestinal pathogenic E. coli, though the ferric yersiniabactin uptake gene (fyuA) was present in PID-associated EnPEC. Endometrial epithelial or stromal cells from wild type but not Toll-like receptor 4 (TLR4) null mice secreted prostaglandin E₂ and chemokine (C-X-C motif) ligand 1 (CXCL1) in response to LPS from EnPEC, highlighting the key role of LPS in PID.

Conclusions/Significance

The implication arising from the discovery of EnPEC is that development of treatments or vaccines for PID should focus specifically on EnPEC and not other strains of E. coli.

Upregulating promoter polymorphisms of RANTES relate to atopic dermatitis

It has been reported that a functional polymorphism in the promoter of the RANTES gene (-403G/A) is associated with atopic dermatitis in a German population. Although there are several reports on the association of RANTES promoter polymorphisms (-403G/A and -28C/G) with asthma, the association of these polymorphisms with atopic dermatitis has not yet been confirmed in other populations. We therefore aimed to test whether the RANTES promoter polymorphisms relate to atopic dermatitis in a well-defined Japanese population. We conducted an association study of upregulating promoter polymorphisms of RANTES (-403G/A and -28C/G) in 389 patients with atopic dermatitis and 177 healthy control subjects. There was a significant association between the upregulating variant of RANTES -28G and atopic dermatitis, while -403A variant showed a significant association with atopic dermatitis with high IgE productivity. These results support a role for RANTES promoter polymorphisms in susceptibility to atopic dermatitis.

Genetic variants of the receptors for thromboxane A2 and IL-4 in atopic dermatitis

Thromboxane A2 (TXA2) is an arachidonate metabolite which is considered to relate to chronic inflammation in atopic diseases characterized by elevated immunoglobulin E productivity. The elevation of immunoglobulin E levels involves many molecules including interleukin-4 (IL-4) and interleukin-4 receptor alpha chain (IL-4R alpha). To assess whether genetic variants of TXA2 receptor, IL-4 and IL-4R alpha genes relate to the elevation of serum immunoglobulin E levels in patients with atopic dermatitis (AD), we conducted an association study of genetic polymorphisms of TXA2 receptor (795C/T), IL-4 (-589C/T), and IL-4R alpha (Ile50Val) in a Japanese population (n = 789). The TXA2 receptor 795TT genotype strongly related to AD with high serum immunoglobulin E concentrations. AD patients with both TXA2 receptor 795TT genotype and the IL-4R alpha Ile50/Ile50 genotype showed the greatest immunoglobulin E concentrations. These results suggest TXA2 receptor polymorphism strongly interacts with IL-4R alpha polymorphism as a major determinant of high serum immunoglobulin E levels in AD.

CB1 receptor mediated analgesia from the Nucleus Reticularis Gigantocellularis pars alpha is activated in an animal model of neuropathic pain

Cannabinoids are known to suppress responses to noxious stimulation in animals and man. Recent research has suggested a role for endogenous cannabinoids in the descending inhibition of dorsal horn cells via a supraspinal site of action. We have recently demonstrated [J. Physiol. 506(2) (1998) 459] that the nucleus reticularis gigantocellularis pars alpha (GiA) is a major source of such descending modulation, and importantly, that this system is activated in response to noxious stimulation. We have therefore investigated the role of CB1 receptor activation in mediating the antinociceptive effects of activation of GiA in models of acute and chronic pain. Microinjections (0.5 microl 60% DMSO) of either WIN 55,212-2 (5 microg, selective CB1 agonist), SR141716A (50 microg, competitive CB1 antagonist), both compounds together, or vehicle alone into GiA were performed prior to these tests in a randomised, blind manner. In control animals, WIN 55,212-2 markedly increased withdrawal latencies in the tail flick test and reduced responses to subcutaneous formalin. These effects were blocked by co-administration of SR141716A. These data suggest that activation of cannabinoid CB1 receptor subtypes in GiA leads to behavioural analgesia. In animals with partial sciatic nerve ligation, microinjection of drugs and injection of formalin were performed contralaterally to the site of ligation. Partial sciatic nerve ligation significantly reduced behavioural responses to contralaterally applied formalin. Microinjection of SR141716A to GiA reversed this inhibition of responses to formalin in animals with partial sciatic nerve ligation. These data provide evidence that endogenous CB1 receptor ligands are involved in GiA mediated antinociception, and that this system is important for the modulation of nociceptive transmission in an animal model of chronic neuropathic pain.

The behavioural importance of dynamically activated descending inhibition from the nucleus reticularis gigantocellularis pars alpha

We have recently demonstrated (J Physiol 506 (1998) 459) that the dynamic activation of descending inhibition of the nociceptive response of spinal multireceptive cells occurs in the nucleus reticularis gigantocellularis pars alpha (GiA). In the same paper we have shown that Lamina I dorsal horn cells are responsible for activating this inhibition via a pathway which runs in the contralateral dorsolateral funiculus. The effects of dynamically activating this system by noxious stimulation on behavioural responses to noxious stimuli have not been established. Here we demonstrate the effects of GiA on the behavioural response during application of standardized noxious stimuli. As this system is activated in response to noxious stimulation (J Physiol 506 (1998) 459), it is possible that chronic pain states may also activate GiA. We have therefore investigated this possibility in animals following partial sciatic nerve ligation (an animal model of chronic pain; Pain 43 (1990) 205). Male Wistar rats (280-310 g) were anaesthetized with halothane (0.5-2% in O(2)). Guide cannulae for microinjections were stereotaxically placed above GiA. In one group of animals the sciatic nerve was partially ligated. Animals were allowed to recover for 4-6 days. The responses of each animal during the formalin test (Pain 4 (1977) 161) and the tail flick test (Pain 12 (1982) 229) were recorded on different days. Microinjections (0.5 microl) of either gamma-aminobutyric acid (GABA, 200 mM), D-L homocysteic acid (DLH, 25 mM) or 0.9% saline (as control) into GiA were performed during these tests in a randomized, blind manner. In animals without sciatic nerve ligation, microinjection of GABA to GiA did not significantly affect the animal's response during the tail flick test. However microinjection of DLH significantly increased the latency of tail flick from 6.2 +/- 0.8 to 8.4 +/- 0.5 s for up to 15 min (n = 7, P < 0.01, Mann-Whitney U-test). Microinjection of GABA to GiA increased the behavioural response to formalin between 10 and 20 min post-injection, while microinjection of DLH reduced this response at all time points except 10 min post-injection (n = 8, P < 0.05, Mann-Whitney U-test). In animals with sciatic nerve ligation, microinjections (0.5 microl) of either GABA (200 mM), or saline (as control) into GiA contralateral to the partial sciatic ligation were performed during these tests in a randomized, blind manner. Partial sciatic ligation significantly reduced the behavioural response to contralaterally applied formalin from 15 min post-injection onwards, compared to controls without sciatic nerve ligation. Microinjection of GABA to GiA significantly increased the behavioural response to formalin from 20 to 50 min post-injection. The inactivation of GiA only causes behavioural effects in nociceptive tests of a long enough duration to activate the system (i.e. the formalin test but not the tail flick test). Chemical activation of the system affects both tests. These data strongly support the concept of an important analgesic system which is activated in response to noxious stimulation, and subsequently acts to reduce behavioural responses to noxious stimuli.

Periaqueductal grey mediated inhibition of responses to noxious stimulation is dynamically activated in a rat model of neuropathic pain

The periaqueductal grey (PAG) has been shown to be a major source of descending inhibition of dorsal horn cells (Textbook of Pain (1999) 309). However, few studies have demonstrated alterations in behavioural responses to noxious stimulation following inactivation of this nucleus. Many behavioural studies have looked for effects on nociceptive withdrawal thresholds in acute nociceptive tests. These tests would not reveal the presence of inhibition which is activated in response to noxious input. We have therefore investigated this possibility by studying behavioural responses to subcutaneous formalin injection in control animals, and in animals following partial sciatic nerve ligation (an animal model of neuropathic pain (Pain 43(2) (1990) 205). In control animals, microinjection of gamma-aminobutyric acid (GABA) to PAG did not significantly alter behavioural responses to formalin, while microinjection of D,L-homocysteic acid (DLH) reduced these responses. Responses to contralaterally applied formalin were significantly reduced in animals with partial sciatic ligation. Microinjection of GABA to PAG significantly increased these behavioural responses to formalin. We conclude that a component of PAG mediated inhibition of nociception is inactive under normal conditions. This inhibition may be activated by persistent nociceptive input, and possibly reflects long term changes in nociceptive circuitry which occur in neuropathic pain states.

Genetic polymorphisms of CC chemokine receptor 3 in Japanese and British asthmatics

Whole genome scan analyses have revealed that chromosomal region 3p21-24, which contains a gene cluster of CC chemokine receptors such as CCR3, is possibly linked to asthma. Because CCR3 ligands play a pivotal role in the selective recruitment and activation of inflammatory cells in the asthmatic airway, the authors examined whether there is any association between asthma and the CCR3 gene polymorphisms. Three polymorphisms were identified using the single stranded conformational polymorphism method in Japanese (Asian) and British (Caucasian) subjects; one silent mutation T51C and two missense mutations G824A and T971C. These polymorphisms were examined in 391 Japanese subjects (210 asthmatics and 181 nonasthmatic controls) and 234 British subjects (142 asthmatics and 92 nonasthmatic controls). Asthma diagnosis was based on episodic symptoms, documented wheeze, and the presence of reversible airflow limitation. CCR3 T51C demonstrated a significant association with the diagnosis of asthma in the British population (odds ratio 2.35, p<0.01), but not in the Japanese population. Multiple logistic regression analysis also showed that CCR3 T51C was associated with asthma (odds ratio 2.83, p < 0.02), independent of atopic phenotypes such as high levels of total or house dust mite-specific immunoglobulin-E in serum. In conclusion, a significant association between asthma and CCR3 T51C polymorphism localized on chromosome 3p21 was found.

Interactive effects of cadmium and benzo[a]pyrene on metallothionein induction in mummichog (Fundulus heteroclitus)

Previous experiments demonstrated that exposure of mummichog to cadmium (Cd) in combination with benzo[a]pyrene (BaP) caused a higher mortality than would be expected from simple additive effects. Experiments are described here that investigated whether BaP exposure inhibits the induction of metallothionein (MT), a major detoxifying protein for Cd, or if reactive BaP metabolites compete with Cd for binding sites on MT. Fish were injected with or without BaP (18 mg/kg) in combination with a low (1 mg/kg) or high (3.2 mg/kg) dose of Cd, and in one treatment BP was dosed 4 days after Cd. The results showed a rapid induction of MT to 1.5 mg/g wet weight liver, 1 day after injecting the low Cd dose. Simultaneous BaP exposure significantly delayed the induction of MT, for both low and high Cd doses, and BaP temporarily lowered the induced MT concentration when dosed 4 days after induction by Cd. To test if binding of BaP metabolites to MT reduces the detoxification potential for Cd, microsomes of CYP1A-induced fish were incubated with MT and radiolabeled BaP. Active metabolism of BaP was observed by high-performance liquid chromatography analysis, but no association of BaP metabolites with MT was found. Neither could this be demonstrated in vivo, in liver MT isolated from mummichog dosed with 3H-BaP and Cd. These results suggest that increased toxicity of Cd in combination with BaP exposure is likely to be caused by inhibited MT synthesis, rather than by interference of BaP metabolites with Cd binding on MT.

The Ile198Thr and Ala379Val variants of plasmatic PAF-acetylhydrolase impair catalytical activities and are associated with atopy and asthma

The platelet-activating factor (PAF) represents a phospholipid with complex biological functions, including involvement in inflammatory processes. The degrading enzyme PAF acetylhydrolase (PAFAH) represents a candidate for asthma and other atopic diseases. Two loss-of-function mutations of PAFAH are associated with severe asthma in Japanese individuals. Our aim was to look for further PAFAH variants in white populations, their possible association with atopic and asthmatic phenotypes, and their functional importance. We picked up three common variants in the PAFAH gene: Arg92His (exon 4), Ile198Thr (exon 7), and Ala379Val (exon 11). The known loss-of-function mutations were not seen. The variant allele Thr198 was found to be highly associated with total IgE concentrations in an atopic population (P=.009) and with "atopic asthma" in an asthmatic population (P=.008). The variant allele Val379 was found to be highly associated with "specific sensitization" in the atopic population (P=.002) and with "asthma" in the asthmatic population (P=.003). By use of recombinant PAFAH enzymes, the variant Val379 showed increased (14 microM) and Thr198 markedly increased (42 microM) KM values compared to the wild type (7 microM); furthermore, Vmax of Val379 was highly increased (132%). Thr198 and Val379 influence plasmatic PAFAH toward lower substrate affinities and therefore are very likely to prolong the activities of PAF. At the same time, they are associated with an increased risk to develop asthma and atopy. Thus, two PAFAH variants seem to play a key role in atopic and asthmatic processes in Caucasian populations.

Genetic variants of IL-13 signalling and human asthma and atopy

Asthma and atopy show epidemiological association and are biologically linked by T-helper type 2 (T(h)2) cytokine-driven inflammatory mechanisms. IL-4 operates through the IL-4 receptor (IL-4R, a heterodimer of IL-4Ralpha and either gammac or IL-13Ralpha1) and IL-13 operates through IL-13R (a heterodimer of IL-4Ralpha and IL-13Ralpha1) to promote IgE synthesis and IgE-based mucosal inflammation which typify atopy. Recent animal model data suggest that IL-13 is a central cytokine in promoting asthma, through the stimulation of bronchial epithelial mucus secretion and smooth muscle hyper-reactivity. We investigated the role of common genetic variants of IL-13 and IL-13Ralpha1 in human asthma, considering IgE levels. A novel variant of human IL-13, Gln110Arg, on chromosome 5q31, associated with asthma rather than IgE levels in case-control populations from Britain and Japan [peak odds ratio (OR) = 2.31, 95% CI 1.33-4.00]; the variant also predicted asthma and higher serum IL-13 levels in a general, Japanese paediatric population. Immunohistochemistry demonstrated that both subunits of IL-13R are prominently expressed in bronchial epithelium and smooth muscle from asthmatic subjects. Detailed molecular modelling analyses indicate that residue 110 of IL-13, the site of the charge-modifying variants Arg and Gln, is important in the internal constitution of the ligand and crucial in ligand-receptor interaction. A non-coding variant of IL-13Ralpha1, A1398G, on chromosome Xq13, associated primarily with high IgE levels (OR = 3. 38 in males, 1.10 in females) rather than asthma. Thus, certain variants of IL-13 signalling are likely to be important promoters of human asthma; detailed functional analysis of their actions is needed.

Variants of NOS1, NOS2, and NOS3 genes in asthmatics

Nitric oxide (NO) gas concentrations are higher in expired air in asthmatics. NO is synthesized by three isoforms of NO synthase (NOS) encoded by three distinct genes, NOS1, NOS2, and NOS3. Genome-wide searches have identified linkages to asthma on chromosomes 7, 12, and 17 where these three genes are localized. No association study, however, has been reported to date. To test whether variants of NOS1, NOS2, and NOS3 relate to asthma, a genetic association study was conducted in a British population (n = 300). Intragenic microsatellite variants of NOS1 were significantly associated with asthma [odds ratio (OR) = 2.08, 95% CI: 1.20-3.57 (95% CI), P = 0.008 (Pc = 0.048)], but not with IgE levels. Neither NOS2 nor NOS3 variants showed any association with asthma nor IgE levels. These findings suggest that NOS1 variants may be a significant contributor to asthma in a British population.

Nonpathogenic common variants of IFNGR1 and IFNGR2 in association with total serum IgE levels

Atopy is an immune disorder in which a Th2 dominant mechanism leads to high IgE levels and the clinical disorder asthma. It has been postulated that the Th1 cytokine IFNgamma, acting through its heterodimeric receptors, IFNgammaR1 and IFNgammaR2, in the induction/proliferation of Th1 cells, might suppress the Th2 responses that may underlie atopic asthma. However, neither murine nor human variants of IFNgamma associate with atopy. Several dysfunctional mutations have been identified in IFNgamma receptor genes (IFNGR1 and IFNGR2) in relation to severe and selective infections with poorly pathogenic organisms. However, little is known about common polymorphisms and their functional role in atopy. To test whether such variants of IFNGR1 and IFNGR2 relate to atopic asthma, we conducted a genetic association study in both British (n = 300) and Japanese (n = 200) populations. An intronic variant of IFNGR1 showed marginal association with total serum IgE levels in the British population compared with those with total IgE levels <30 IU/ml and those with >120-500 IU/ml [odds ratio = 2.00 (95% CI 1. 00-4.07), P = 0.048]. A coding variant, Gln64Arg of the IFNGR2, also associated with total serum IgE levels in the British population [chi(2) = 5.08, P = 0.024]. Further genetic and functional analyses are needed to clarify the role of variants of IFNgamma receptor genes in atopic immune disorder among different ethnic groups.

Variants of endothelin-1 and its receptors in atopic asthma

Endothelin-1 (ET-1) is a 21 amino acid peptide released from several types of bronchial cells. It operates through two types of receptors, type A(ET-RA) and type B(ET-RB) and has various activities in the pathophysiology of atopic asthma. These genes are localised on different chromosomes where genome-wide searches have identified linkage for atopic asthma, thus supporting the candidacy of ET-1 and its receptors for atopic asthma. A genetic association study was performed with variants of these three genes in both British (n = 300) and Japanese populations (n = 200). No significant association was found between variants of EDN1 and EDNRB genes, and atopic asthma in either population. However, variants of EDNRA gene showed a marginal association with atopy [odds = 0.39(95% CI: 0.17-0.89), p = 0.022, Pc = 0.066], especially with antigen specific IgE levels [odds = 0.31 (95% CI: 0.20-0.77), p = 0.006, Pc = 0.018] in the British population. These findings suggest that EDNRA is a major candidate locus for atopy on chromosome 4.

Toxicity of creosote water-soluble fractions generated from contaminated sediments to the bay mysid

Creosote, a globally used wood preservative, is a complex mixture consisting primarily of aromatic organic compounds (ACs). Creosote-derived ACs can persist for decades in aquatic sediments. Natural and anthropogenic activities may result in dissolution and resuspension of sediment-associated ACs. These processes were mimicked by generating a water-soluble fraction (WSF) from creosote-contaminated sediment (ERS) collected from a polluted site. The epibenthic mysid Mysidopsis bahia was exposed to five sublethal concentrations of WSF for 7 days. The WSF significantly decreased dry weight gain and proportion of gravid females (EC50=15 microgram/liter total identified ACs). Chemical analysis indicated that high-molecular-weight ACs (more than three aromatic rings) dominated the ERS, but were undetected in the WSF. Low-molecular-weight ACs (fewer than three aromatic rings) dominated the WSF. Compositional differences can thus result from fractionation processes and affect environmental fate and toxicity of the mixture.

Supraspinal inhibition of nociceptive dorsal horn neurones in the anaesthetized rat: tonic or dynamic?

1. Tonic inhibition of sensory spinal neurones is well known to descend from the rostroventral medulla. It is not clear if this inhibition is dynamically activated by peripheral noxious stimuli. 2. Transection of the ipsilateral dorsolateral funiculus (DLF) removed a descending inhibition of multireceptive spinal neurones and disproportionally prolonged the after-discharge component of their response to a noxious cutaneous stimulus. 3. Microinjection of GABA or tetracaine into the medullary nucleus gigantocellularis pars alpha (GiA) similarly prolonged the after-discharge in response to noxious stimuli. 4. Recordings of GiA cells, initially using minimal surgery, revealed that many had low levels of spontaneous activity and responded vigorously to noxious stimuli applied to any part of the body surface. One hour after the surgery necessary to expose the spinal cord, GiA cells had a high firing rate but responded weakly to noxious stimuli. 5. The response of GiA cells to noxious stimuli was abolished by transection of only the DLF contralateral to the stimulus. 6. It is concluded that the inhibition of multireceptive dorsal horn neurones from GiA is dynamically activated by noxious cutaneous stimuli via a projection in the contralateral DLF. Surgical exposure of the spinal cord tonically activates this inhibition and masks the dynamic component.

The cyclin-dependent kinase (cdk) inhibitors, olomoucine and roscovitine, alter the expression of a molluscan circadian pacemaker

1. In this study, we determined the effects of the cyclin-dependent kinase (cdk) inhibitors, olomoucine and roscovitine, on the circadian rhythm of optic nerve impulse activity recorded from the eye of the marine snail Bulla gouldiana. 2. We found that olomoucine lengthened period and altered circadian phase in a dose-dependent manner without appreciably affecting gene transcription or translation. We also found that the more specific cdk inhibitor, roscovitine, was approximately 10-fold more effective in lengthening circadian period, while the inactive analogue, iso-olomoucine, was ineffective. 3. The current results, along with previous results from our laboratory, are consistent with the hypothesis that the biochemical mechanism responsible for generating the ocular circadian rhythm in B. gouldiana is related to the biochemical mechanism that regulates the eukaryotic cell division cycle, i.e., by modulation of the activity of protein kinases belonging to the cdk family.

Phase relationship between ocular and behavioral circadian rhythms in Bulla gouldiana exposed to different photoperiods

To determine whether the ocular circadian pacemakers of the marine snail Bulla gouldiana exert phase control over the circadian rhythm in locomotor activity, we measured the phase angles for entrainment of the ocular pacemakers and the activity rhythm on four different photoperiods: L:D 15:9, 12:12, 9:15, and 4:20. We found that the phase angle for ocular entrainment was progressively advanced relative to dawn as photoperiod decreased, although the phase was fixed relative to the middle of the day. In contrast, activity began near dusk on all photoperiods. On subsequent release into constant conditions, the free-running locomotor activity commenced near the time of previous activity onset. Thus, activity phase on light cycles represents the entrainment of a light sensitive pacemaker. The resulting lability in phase between ocular and behavioral rhythms in Bulla exposed to light cycles suggests that the ocular pacemakers are not the only determinants of locomotor activity phase in Bulla.

Efferent connections from the anterior pretectal nucleus to the diencephalon and mesencephalon in the rat

The anterior pretectal nucleus has been described as part of the visual pretectal complex. However, several electrophysiological and behavioural studies showed that this area is involved in somatosensory modulation, more specifically, antinociception. The efferents of the anterior pretectal nucleus have not been identified taking into account the different function of this nucleus in relation to the rest of the pretectal complex. In the study herein described, a sensitive anterograde tracer Phaseolus vulgaris leucoagglutinin was used to trace the mesencephalic and diencephalic efferents of the anterior pretectal nucleus in the rat. The majority of the connections were ipsilateral. Fibres with varicosities were observed in discrete areas of the thalamus (central lateral, posterior complex), hypothalamus (lateral, posterior and ventromedial), zona incerta, parvocellular red nucleus, intermediate and deep layers of the superior colliculus, central grey, deep mesencephalon, pontine parabrachial region, and pontine nuclei. Fibres en passant were detected in the medial lemniscus, from the level of the injection site to rostral medullary levels. Some labelled axons were seen coursing to the contralateral side through the posterior commissure and the decussation of the superior cerebellar peduncle. These results show that the anterior pretectal nucleus projects principally to areas involved in somatosensory and motor control in a manner that permits sensory modulation at higher and lower levels of the brain. These connections may explain the antinociceptive and antiaversive effects of stimulating the anterior pretectal nucleus in freely moving animals.

Anterior pretectal nucleus facilitation of superficial dorsal horn neurones and modulation of deafferentation pain in the rat

1. Functional relationships between the anterior pretectal nucleus (APTN) and nociceptive dorsal horn neurones were investigated electrophysiologically in the anaesthetized rat. The effects of APTN lesions were assessed behaviourally in a model of deafferentation pain. 2. Cells in the dorsal and rostral parts of the APTN were excited orthodromically by electrical stimulation of the ipsilateral dorsolateral funiculus or the contralateral dorsal columns, and by noxious and innocuous cutaneous stimuli. 3. Electrical stimulation of the APTN excited nociceptive lamina I spinal neurones. These cells all projected rostrally in the contralateral dorsolateral funiculus. Identical APTN stimulation also inhibited multireceptive spinal neurones which lay deep in the dorsal horn. These particular cells were shown to project to the brain in the ventrolateral funiculus. 4. It is proposed that noxious stimuli excite spinal lamina I projection neurones which send excitatory axons to the brain, including the APTN. The APTN inhibits deep multireceptive neurones, to reduce the perception of noxious stimuli. The discharge of spinal lamina I neurones, however, will be sustained by the noxious stimulus and by facilitation from the APTN. A sustained descending inhibition of this nature would reduce responses to prolonged injury. 5. The involvement of the APTN in responses to a chronic pain state was examined by comparing the behaviour of animals with bilateral lesions of the APTN with normal controls. Lesions of the APTN strongly enhanced the autotomy behaviour triggered by sectioning of the dorsal roots. 6. These observations support the suggestion that the APTN reduces the debilitating effects of prolonged injury.

Direct projections from the anterior pretectal nucleus to the ventral medulla oblongata in rats

The anterior pretectal nucleus has recently been implicated in the descending modulation of nociception. Electrical stimulation of the nucleus was found to reduce the nociceptive responses of deep dorsal horn neurons and to inhibit spinally integrated withdrawal reflexes. It is believed that at least part of the descending inhibitory effects of the anterior pretectal nucleus are mediated by reticulospinal cells of the ventrolateral medulla. The purpose of the present study was to trace the direct medullary projections of the anterior pretectal nucleus, to describe their topographical organization and to reveal the chemical nature of some of their putative target cells. The connections were studied using anterograde tract-tracing with Phaseolus vulgaris leucoagglutinin. Direct projections from the anterior pretectal nucleus to the ipsilateral rostral ventral medulla were found in all cases. A dense innervation of the dorsal inferior olive, the gigantocellular reticular nucleus pars ventralis and pars alpha and the ventral pontine reticular nucleus was found from all aspects of the anterior pretectal nucleus. Descending labelled terminals were also observed in the gigantocellular reticular nucleus proper and, laterally, in the lateral paragigantocellular nucleus and in the region of the A5 noradrenergic cell group. A relatively lower density of labelled terminals was noted in the medullary raphe nuclei and in the rostroventrolateral reticular nucleus. Following tract-tracer injections into five distinct subregions of the anterior pretectal nucleus, the topographical organization of the projection was examined and the relatively highest density and most widespread projection was found to originate from the caudoventral part of the anterior pretectal nucleus. A combined tract-tracing and immunolabelling study revealed that some of the descending, labelled terminals were in close proximity of tyrosine hydroxylase-immunoreactive dendrites in the C1 and A5 cell groups. Some labelled fibres were also noted among the serotonin-immunoreactive cells in the lateral extension of the B3 cell population. The existence of direct projections to the ventral medulla and pons correlates well with physiological data which showed that the descending, antinociceptive effects of the anterior pretectal nucleus are relayed via the rostral ventrolateral medulla. The data are also in keeping with pharmacological studies that suggested the role of catecholaminergic cells in the mediation of these descending effects. It is proposed that the rostral ventral medullary projections provide a path through which antinociceptive effects of the anterior pretectal nucleus are mediated to the spinal cord.

Identification of CDK- and cyclin-like proteins in the eye of Bulla gouldiana

The ocular circadian rhythm in the eye of Bulla gouldiana is generated by a rhythm in membrane potential of retinal neurons that is driven by alterations in potassium conductance. Since potassium conductance may be modulated by the phosphorylation of potassium channels, the circadian rhythm may reflect rhythmic changes in protein kinase activity. Furthermore, the circadian rhythm recorded from the Bulla eye can be phase shifted by agents that affect protein synthesis and protein phosphorylation on tyrosine residues. Interestingly, the eukaryotic cell division cycle is generated by similar processes. Rhythmic cell division is regulated by periodic synthesis and degradation of a protein, cyclin, and periodic tyrosine phosphorylation of a cyclin-dependent kinase (cdk), p34cdc2. The interaction between these two proteins results in rhythmic kinase activity of p34cdc2. Both cyclin and p34cdc2 are part of two diverse gene families, some of whose members have been localized to post-mitotic cell types with no function yet determined. In the current work, we identify proteins similar to the cdks and cyclin in the eye of Bulla. Neither of these ocular proteins are found in mitotic cells in Bulla, and the cdk-like protein (p40) is specific to the eye. Furthermore, the concentration of the cyclin-like protein (p66) is affected by treatments that phase shift the circadian rhythm. The identification of cdk and cyclin-like proteins in the Bulla eye is consistent with the hypothesis that the biochemical mechanism responsible for generating the ocular circadian rhythm in Bulla is related to the biochemical mechanism that regulates the eukaryotic cell division cycle.

The pontine parabrachial region mediates some of the descending inhibitory effects of stimulating the anterior pretectal nucleus

Electrical stimulation of the anterior pretectal nucleus (APtN) elicits antinociception by inhibiting the responses of spinal multireceptive neurones to noxious stimuli. This descending inhibition is mediated, in part, by activating cells in the ventrolateral medulla. Neuronal tract tracing has previously shown that the APtN also projects directly to the pontine parabrachial region (PPR). The PPR, investigated by Katayama et al. (Brain Res., 296 (1984) 263-283), corresponds to the cholinergic cell group Ch5 of Mesulam et al. (Neuroscience, 10 (1983) 1185-1201). In this study, the pathway from APtN to PPR was investigated using urethane anaesthetised rats. Electrical stimulation (single square wave 0.2 ms pulses, 1-10 V, 5 Hz) of the APtN potently excites 40% of the cells recorded in the PPR. In the reverse experiment, stimulation of the PPR at the same parameters excited 36% of the cells recorded in the APtN. The contribution of this pathway to the spinal inhibitory effects of APtN stimulation was then examined. Unanaesthetised animals received electrical stimulation to the APtN (35 microA r.m.s., 15 s) and the increase in tail-flick latencies was measured. Bilateral electrolytic lesions of the PPR caused a 67% reduction of the antinociceptive effect of APtN stimulation. In urethane anaesthetised rats, microinjection of tetracaine into the PPR blocked the inhibition of multireceptive dorsal horn neurones caused by APtN stimulation (20 s train of 50 microA square wave 0.1 ms pulses, 100 Hz). In conclusion, these experiments strongly sugget that the PPR may be an important part of a descending antinociceptive pathway originating in the APtN.

Tyrosine kinase regulation of a molluscan circadian clock

On a formal level the clocks regulating circadian and cell division cycles are related in that both have been modeled as limit cycle oscillations (Science, 211 (1981) 1002-1013; Brain Res., 504 (1989) 211-215; Proc. Natl. Acad. Sci. USA, 88 (1991) 7328-7332). Furthermore, in several organisms each clock system is able to modulate the other (Science, 211 (1981) 1002-1013). However, in spite of the similarities at the formal level, and the connections at the physiological level, no common cellular elements have been identified linking the two processes. In the current series of experiments we show that one key element of cell cycle regulation, tyrosine phosphorylation/dephosphorylation is intimately associated with circadian rhythm generation in the eye of the marine snail, Bulla gouldiana. The importance of tyrosine kinase activity in the generation of circadian rhythms provides a possible point of similarity between the fundamental biochemical mechanisms underlying both circadian and cell cycle clocks.

A post-synaptic depressant modulatory action of 5-hydroxytryptamine on excitatory amino acid responses in rat entorhinal cortex in vitro

The depressant action of 5-hydroxytryptamine (5-HT) in slices of entorhinal cortex of the rat has been examined. When single intracellular recordings of pyramidal cells in layers II/III of entorhinal cortex of the rat were made and drugs applied by iontophoresis, 5-HT evoked virtually no changes in passive membrane properties of the majority of cells studied. When short regular pulses of glutamate were applied to the neurones and 5-HT was ejected in addition, the depolarisations caused by glutamate were considerably reduced in amplitude. This attenuation persisted in medium containing cadmium chloride (200 microM) to block synaptic transmission. The magnitude of the response to 5-HT was dependent on the ejection current and this effect could not be mimicked by increasing ejections of Na+ or H+ ions. 5-Hydroxytryptamine had no apparent action on neuronal responses to iontophoretically ejected gamma-amino butyric acid (GABA). In later studies, the action of 5-HT was examined on epileptiform discharges, evoked in the presence of the GABA antagonist, bicuculline, in the same group of cells. Droplet application of 5-HT into the recording chamber, or perfusion of 10 microM 5-HT regularly attenuated the length of epileptiform bursts but, at this concentration, had no discernible effect on the resting membrane potential or membrane input resistance. The effect of 5-HT on the release of glutamate from slices of entorhinal cortex has also been examined using a fluorometric enzyme assay. Concentrations of 5-HT as large as 30 microM had no effect on the release of endogenous glutamate in these experiments.(ABSTRACT TRUNCATED AT 250 WORDS)

The prevalence of cognitive impairment in a community survey of multiple sclerosis

A one in two alternate sample (N = 200) from a population-based register of 411 people with multiple sclerosis (MS) was studied. Out of this sample, 147 people with MS and 34 people with rheumatoid arthritis were interviewed at home and completed a battery of neuropsychological tests. Cognitive impairment was found in 46 per cent of those with MS, with memory impairment in 34 per cent and failure on tests of frontal lobe function in 33 per cent. Physical disability was associated with cognitive impairment. Memory impairment was more common in those who had had MS for 10 years or more. A significant minority of people with mild physical disability and some who had had MS for less than a decade nevertheless had cognitive impairment. Relationships between cognitive impairment, other disease variables and psychosocial factors were examined. Counselling and rehabilitation programmes for people with MS and their families should take account of cognitive deficits that may be present.

Electrophysiological evidence for excitatory 5-HT2 and depressant 5-HT1A receptors on neurones of the rat midbrain tectum

It has been claimed that the aversive behaviour induced by electrical stimulation of the midbrain tectum (MT) has validity as an animal model of panic attack. A great deal of evidence obtained from behavioural studies suggests that 5-HT2 mechanisms phasically inhibit the substrates of aversion in the MT. In order to test this hypothesis we employed the technique of microiontophoresis of drugs onto neurons of the MT to assess the identity of the receptors mediating the effects of 5-hydroxytryptamine (5-HT). The results obtained show that the majority of 5-HT responsive cells in MT are cells excited by 5-HT (72%). These cells were silent or showed very low spontaneous firing activity, whereas cells depressed by 5-HT showed high spontaneous firing activity at baseline. The 5-HT1A receptor agonists, 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT), buspirone and gepirone caused consistent reduction in the firing rate of cells depressed by 5-HT while they did not change the firing activity of cells excited by 5-HT. The excitatory effects induced by 5-HT on MT neurones were clearly attenuated by concomitant application of ketanserin, a highly specific 5-HT2 antagonist. Excitatory responses to DL-homocysteic acid were not affected by ketanserin. Previous administration of zimelidine, a selective 5-HT uptake inhibitor, caused a significant enhancement of the excitatory effects of 5-HT while similar application of gepirone did not affect the size of the excitatory responses to 5-HT.(ABSTRACT TRUNCATED AT 250 WORDS)

Monoclonal antibodies recognize localized antigens in the eye and central nervous system of the marine snail Bulla gouldiana

The eyes of the marine snail Bulla gouldiana act as circadian pacemakers. The eyes exhibit a circadian variation in spontaneous optic nerve compound action potential frequency in constant darkness, and are involved in controlling circadian rhythms in behavioral activity expressed by the animal. To initiate an investigation of the molecular aspects of circadian rhythmicity in the Bulla eye and to identify specific molecular markers in the nervous system, we raised monoclonal antibodies (MAb) to the eye and screened them for specific patterns of staining in the eye and brain. Several MAb recognize antigens specific to groups of neurons in the brain, whereas others stain antigens found only in the eye. In addition, some antigens are shared by the eye and the brain. The antigens described here include molecules that mark the lens, retina, neural pathways between the eye and the brain, specific groups of neurons within the central ganglia, and an antigen that is shared by basal retinal neurons (putative ocular circadian pacemaker cells) and glia. These molecular markers may have utility in identifying functionally related groups of neurons, elucidating molecular specializations of the retina, and highlighting pathways used in transmission of information between the retina and the brain.

Central antiaversive and antinociceptive effects of anterior pretectal nucleus stimulation: attenuation of autonomic and aversive effects of medial hypothalamic stimulation

Previous studies have shown that stimulation of the rat anterior pretectal nucleus (APtN) strongly depresses a spinal reflex to noxious heat without causing significant aversion or depression of other motor responses. It is not known if APtN stimulation can similarly reduce the aversiveness of electrical stimulation of the brain, nor is it known if APtN stimulation is itself rewarding or aversive. This study used a simple switch-off paradigm to examine the rewarding properties of APtN stimulation at different sites throughout the nucleus and also used the tail-flick test to determine if the stimulation produced antinociception. The effects of APtN stimulation on the behavioural and autonomic responses to electrical stimulation of the medial hypothalamus (MH) and the nucleus raphe magnus (NRM) were also examined. The results show that electrical stimulation of dorsal APtN was rewarding and also caused antinociception which lasted for 50 min. However, sites which gave the strongest reward were not necessarily those which gave the greatest antinociception, as these effects were not correlated. Electrical stimulation of ventral APtN induced only aversive effects. The aversive and autonomic effects of MH stimulation were significantly reduced by conditioning stimulation of dorsal APtN. However, the very similar escape and autonomic effects of NRM stimulation were unaffected by APtN stimulation. These results suggest that electrical stimulation of the dorsal parts of the APtN has positive rewarding properties as well as the well-known antinociceptive effects. The antiaversive effects of dorsal APtN stimulation may be due in part to the inhibition of central substrates of aversion as well as inhibition of sensory neurones.

The prevalence of multiple sclerosis in the Southampton and South West Hampshire Health Authority

A first survey of the Southampton and South West Hampshire Health Authority showed an overall prevalence of multiple sclerosis of 99/100,000 in a population of 417,000 on 1 January 1987. This finding is similar to other recent first surveys in the South of the United Kingdom and only repeat surveys will show if case only repeat surveys will show if case ascertainment has been more complete in these than earlier first studies in Scotland.

The actions of the novel anti-aggressive drug eltoprazine on central neurones in the anaesthetised rat

5-Hydroxytryptamine (5-HT) and the novel anti-aggressive drug eltoprazine (1-(2,3-dihydro-1,4-benzodioxin-5-yl) piperazine hydrochloride) were applied by microiontophoresis to spinal motorneurones and also to neurones in the brainstem which gave two distinctly different responses to 5-HT. In vitro microiontophoretic release studies showed that the electrophoretic mobility of eltoprazine and 5-HT were similar and that similar amounts of each drug would be applied by similar iontophoretic currents. Cells in the brainstem have been shown previously to be excited by 5-HT, acting at a 5-HT2 receptor. Eltoprazine only occasionally and weakly mimicked the excitatory effect of 5-HT on these cells. Although a potent antagonism of the 5-HT excitation by eltoprazine was observed, this was a non-selective effect, as responses to glutamate and D,L-homocysteic acid were also reduced. Cells in the lateral brainstem are depressed by 5-HT, acting on a receptor which has previously been shown to be of the 5-HT1-like group. At this receptor, 8-OH-DPAT (8-hydroxy-2-(di-n-propylamino)-tetralin) and 5-carboxamidotryptamine, are potent agonists. Eltoprazine was a more potent depressant agonist than 5-HT on these brainstem neurones. The antagonist metergoline did not antagonise responses to either 5-HT or eltoprazine. It is suggested however that both drugs act at the same receptor to depress these cells because desensitizing the receptor by repeated, frequent applications of 5-HT abolished responses to 5-HT and eltoprazine, without altering responses to GABA.(ABSTRACT TRUNCATED AT 250 WORDS)

Kinase inhibition lengthens the period of the circadian pacemaker in the eye of Bulla gouldiana

The inhibition of protein kinase activity by the isoquinoline sulfonamide, H-8, lengthens the period of the Bulla ocular circadian rhythm in a dose-dependent manner. In addition, the phosphorylation of 5 proteins is markedly affected by H-8. The observed correlation between H-8's period lengthening effects, and its effects on the phosphorylation of specific proteins, suggests that: (1) these proteins are candidate components regulating the period of the circadian rhythm; and (2) the daily changes in membrane potential underlying the circadian rhythm are mediated by similar mechanisms that serve to change neural function in other systems; modulation of protein kinases.

Activation of cells in the anterior pretectal nucleus by dorsal column stimulation in the rat

1. The responses of neurones in the anterior pretectal nucleus (APTN) to electrical stimulation of the dorsal columns at twice the threshold for A fibres were studied in the rat anaesthetized with urethane. 2. APTN cells were excited by dorsal column stimulation. Forty-six discharged phasically in response to a single stimulus. Sixteen cells did not respond phasically but slowly increased the discharge rate with repeated stimulation. 3. Electrical stimulation of the contralateral gracile fasciculus caused neurones in the APTN to discharge with a variable latency of 2-22 ms. Stimulations of the ipsilateral gracile and contralateral cuneate fasciculi had weaker effects. 4. Microinjection of DL-homocysteic acid into the contralateral gracile nucleus increased the discharge rate of APTN neurones. Microinjection of gamma-aminobutyric acid into the contralateral gracile nucleus blocked the gracile fasciculus evoked excitation of APTN neurones. 5. On thirteen occasions cells in the gracile nucleus were driven antidromically by electrical stimulation of the APTN. 6. It is concluded that electrical stimulation of the gracile fasciculus activates a monosynaptic excitatory input to the APTN.

Antinociceptive effects of dorsal column stimulation in the rat: involvement of the anterior pretectal nucleus

1. The effects of stimulating A fibres in the dorsal columns on the responses of dorsal horn neurones to intense cutaneous stimuli were studied in the rat anaesthetized with urethane. 2. Multireceptive cells deep in the lumbar dorsal horn were excited for 5-10 ms by dorsal column stimulation and subsequently responses to noxiously hot water placed on the cutaneous receptive field were reduced for the following 4-5 min. Seven of the cells studied projected to the brain via the contralateral anterolateral funiculus. 3. If the discharge of the multireceptive neurones was raised by ionophoretic application of DL-homocysteic acid, a brief period of inhibition lasting for 100-150 ms was seen following a single stimulus to the dorsal columns. Studies were conducted to determine if this brief inhibition could account for the long-lasting inhibition of responses to high-threshold stimuli. 4. Dorsal columns were transected at cervical levels. Stimulation caudal to the transection evoked only the brief excitation and subsequent inhibition for 100-150 ms. No long-lasting inhibition of high-threshold cutaneous afferent input was seen. 5. Stimulation of the dorsal columns rostral to transection did not evoke the brief excitation or inhibition of multireceptive dorsal horn neurones. However, the 4-5 min inhibition of responses to high-threshold cutaneous stimuli was present. 6. The long-lasting inhibition of responses to high-threshold stimuli by dorsal column stimulation was blocked by microinjection of gamma-aminobutyric acid into the anterior pretectal nucleus (APTN) but not by microinjections into adjacent areas of the brain. 7. Ipsilateral lesions of the dorsolateral funiculus at the cervical level also blocked the long-lasting inhibitory effects of dorsal column stimulation. 8. It is concluded that the brief excitation and inhibition of multireceptive dorsal horn neurones is due to antidromic action potentials passing caudally in the dorsal columns to activate spinal segmental mechanisms. The longer-lasting inhibition of responses to high-threshold cutaneous stimuli is due to action potentials ascending in the dorsal columns to activate cells in the APTN which in turn activate a descending inhibition mediated by the dorsolateral funiculus.

Involvement of serotonin in nociceptive pathways

New approaches in the design of analgesics emerged from the discovery that serotonin (5HT) is involved in the descending system (brain to spinal cord) that inhibits signals from peripheral nociceptors. However, the simple hypothesis that 5HT is a transmitter in this system requires elaboration, since not all agonists of 5HT are analgesics. In this commentary, the following questions are discussed: (a) do 5HT systems influence all responses to all types of noxious stimuli?, (b) is a 5HT synapse a necessary link in the analgesic system, (c) what is the location of the relevant 5HT receptor?, and (d) what is the relevant 5HT receptor subtype? The need for more adequate definition of the relevant 5HT receptor is stressed. Once this is achieved, a more rational approach to analgesic drug discovery will be provided by the design of selective agonists of this receptor.

Structural and functional analysis of raphe neurone implants into denervated rat spinal cord

The ability of grafts of embryonic raphe cells to the adult rat spinal cord to reverse the morphological, neurochemical and functional deficits caused by ablation of the serotoninergic afferents has been studied. After grafting, extensive reinnervation was observed by 5HT-immunoreactive fibres, many of which appeared to make contacts with host motoneurones. The neurotransmitter complement was apparently normal. There was also a reinstatement of 5HT levels in the denervated cord after transplantation, amounting to some 40% of normal at the level of the graft. Similarly, Na+-dependent uptake of [3H]-5HT into P3 fractions was over 40% of that recorded in unlesioned animals. Antidromic stimulation of the ventral roots of the spinal cord was used to assess the degree of motoneurone excitability. The field potential in the ventral horn of grafted animals was increased by electrical stimulation of discrete regions along the cord, probably corresponding to the graft loci. It is concluded that serotoninergic neurones transplanted to the denervated spinal cord survive and develop normally, reinnervating the host tissue extensively. Furthermore, the graft/host connections appear to be functionally viable.

Afferent projections to the rostral anterior pretectal nucleus of the rat: a possible role in the processing of noxious stimuli

The afferent inputs to the rostral pole of the anterior pretectal nucleus have been examined by utilizing the retrograde axonal transport of a fluorescent dye, Fast Blue. After unilateral injection of the dye into the rostral anterior prectectal nucleus, large numbers of labelled neuronal somata were found in the somatosensory cortex, the ventrolateral geniculate nucleus, the zona incerta, the superior colliculus, the deep mesencephalic nuclei, the pedunculopontine tegmental nucleus and the medial vestibular nucleus. In addition, the contralateral parabigeminal nucleus provided a major input to the rostral part of the anterior pretectal nucleus. Smaller and sparser collections of stained cell bodies could be found in the ventromedial hypothalamus, the posterior pretectal nucleus, the nucleus of the posterior commissure, the peripeduncular nucleus, the periaqueductal central gray, the contralateral anterior pretectal nucleus, and the locus coeruleus. Many of the inputs originated in areas associated with nociceptive pathways. The regional distribution of neurons projecting to the rostral pole of the anterior pretectal nucleus differs substantially from that of the cells innervating the anterior pretectal nucleus proper, i.e. its more caudal parts. It is concluded from this that the rostral pole constitutes a separate nucleus, anatomically distinct from the rest of the anterior pretectal nucleus and other cell groups in the pretectal complex. The demonstration that many of the afferents to the rostral anterior pretectal nucleus arise in regions involved in nociception supports recent electrophysiological and behavioural evidence that this brain area plays a role in the processing of noxious stimuli, rather than as a component in the pretectal control of visual system reflexes.

The central nervous system of Bulla gouldiana: peptide localization

In the present study, we describe the structure of the central nervous system (CNS) of the marine gastropod Bulla gouldiana, and compare it with the structure of the CNS of the related mollusc, Aplysia californica. In addition, we performed an immunohistochemical analysis of a series of peptides, and the synaptic vesicle protein, synapsin I, in the central nervous system of B. gouldiana. The most common peptide in the B. gouldiana nervous system is the molluscan cardioexcitatory peptide (FMRFamide), which is present in a significant proportion of B. gouldiana neurons. A smaller number of neurons exhibit immunoreactivity to antisera raised against the calcitonin gene related peptide, vasopressin, vasoactive intestinal peptide, cholecystokinin, galanin and enkephalin. In some instances there is colocalization of two or more peptides. Very few neurons or axons exhibit synapsin I-like immunoreactivity. The patterns of immunoreactivity to these antisera is quite similar to the patterns that have been described in other gastropods, including Lymnaea stagnalis and Aplysia californica. These observations emphasize the importance of FMRFamide-like compounds in phylogenetically old nervous systems and indicate that compounds similar to mammalian peptides are present in the gastropod. Thus, the production of a wide variety of peptide molecules and their use in neuronal function appears to be a highly conserved phylogenetic process.