Helen C. Gallagher

The 5-HT(6) receptor antagonist SB-271046 reverses scopolamine-disrupted consolidation of a passive avoidance task and ameliorates spatial task deficits in aged rats.

The highly potent and selective 5-HT6 receptor antagonist SB-271046 [5-chloro-N-(4-methoxy-3-piperazin-1-yl-phenyl)-3-methyl-2-benzothiophenesulfonamide] has previously been demonstrated to improve retention significantly in a spatial water maze paradigm in adult rats. However, SB-271046 did not have any effect on task acquisition. As these apparently contradictory findings may be reconciled by a prime influence of SB-271046 on memory consolidation, the ability of this compound to reverse the discrete temporal action of a cholinergic antagonist in the 6-h period following passive avoidance training was investigated. SB-271046, given orally, by gavage, 30 min prior to training Wistar rats in a step-through, light–dark passive avoidance task, was found to reverse significantly the amnesia produced by administering scopolamine (0.8 mg/kg, intraperitoneal) in the 6-h post-training period. The effect was dose-dependent over a range of 3–20 mg/kg. Further, we investigated the cognition-enhancing effects of chronic SB-271046 administration (10 or 20 mg/kg/day; 40 days) on the acquisition and consolidation of a water maze spatial learning task in a population of 20-month-old Wistar rats with age-related learning deficits. Drug treatment progressively and significantly decreased platform swim angle and escape latencies over the five sequential trials on four consecutive daily sessions compared to vehicle-treated controls. SB-271046 also improved task recall as measured by significant increases in the searching of the target quadrant on post-training days 1 and 3, when the animals would have been substantially drug-free. This significant improvement of task recall suggests SB-271046, in addition to inducing symptomatic cognition-enhancing actions, also attenuates age-related decline in neural function.

A Synthetic Peptide Ligand of Neural Cell Adhesion Molecule (NCAM) IgI Domain Prevents NCAM Internalization and Disrupts Passive Avoidance Learning

Abstract: The neural cell adhesion molecule (NCAM) mediates cell adhesion and signal transduction through trans‐homophilic‐ and/or cis‐heterophilic‐binding mechanisms. Intraventricular infusions of anti‐NCAM have revealed a functional requirement of NCAM for the consolidation of memory in rats and chicks in a specific interval 6‐8 h after training. We have now extended these studies to a synthetic peptide ligand of NCAM (C3) with an affinity for the IgI domain and the capability of inhibiting NCAM‐mediated neurite outgrowth in vitro. Intraventricular administration of a single 5 μg bolus of C3 strongly inhibited recall of a passive avoidance response in adult rats, when given during training or in the 6‐8‐h posttraining period. The effect of C3 on memory consolidation was similar to that obtained with anti‐NCAM as the amnesia was not observed until the 48‐h recall time. The unique amnesic action of C3 during training could be related to disrupted NCAM internalization following training. In the 3‐4‐h posttraining period NCAM 180, the synapse‐associated isoform, was down‐regulated in the hippocampal dentate gyrus. This effect was mediated by ubiquitination and was prevented by C3 administration during training. These findings indicate NCAM to be involved in both the acquisition and consolidation of a passive avoidance response in the rat. Moreover, the study provides the first in vivo evidence for NCAM internalization in learning and identifies a synthetic NCAM ligand capable of modulating memory processes in vivo.

Increased incidence of postoperative cognitive dysfunction 24 hr after minor surgery in the elderly

PurposePostoperative cognitive dysfunction (POCD) is evident in 26% of elderly patients seven days after major non-cardiac surgery. Despite the growing popularity of day surgery, the influence of anesthetic techniques on next day POCD has not been investigated. Therefore, we evaluated the incidence of POCD and changes in serum markers of neuronal damage (S-100ß protein and Neuron-Specific Enolase), 24 hr after single-agent propofol or sevoflurane anesthesia in elderly patients undergoing minor surgery.MethodsPatients (n = 30, mean age 73, range 65–86 yr) coming for cystoscopy or hysteroscopy, were randomized, in an observer-blind design, to receive either single-agent propofol or sevoflurane anesthesia. Changes in neuropsychological tests (the Stroop test and the modified Word-Recall Test), 24 hr postoperatively were compared with age-matched control subjects (n = 15) using Z-score analysis. Changes in S-100ß protein and Neuron-Specific Enolase levels were also documented.ResultsPOCD was present in 7/15 [47% (95% confidence interval (CI) 21 to 72%)] patients who received propofol and 7/15 [47% (95% CI 21 to 72%)] patients who received sevoflurane, compared with 1/15 [7% (95% CI 6 to 19%)] control patients, P = 0.03. S-100ß protein and Neuron-Specific Enolase levels were not significantly different in anesthetized patients postoperatively compared with preoperative values.ConclusionThe incidence of POCD in elderly patients on the first day after minor surgery is higher than previously reported for seven days after major surgery, and is increased after both propofol and sevoflurane anesthesia, compared with age-matched controls. S-100ß protein and Neuron-Specific Enolase levels were unaffected by anesthetic technique.RésuméObjectifLe dysfonctionnement cognitif postopératoire (DCPO) se manifeste chez 26% des patients âgés, sept jours après une opération non cardiaque majeure. Nous avons évalué l’incidence de DCPO et les modifications des marqueurs sériques d’atteinte neuronale (protéine S- 100ß et énolase neurospécifique), 24 h après une anesthésie à un seul médicament, le propofol ou le sévoflurane, chez des patients âgés qui ont subi une opération mineure.MéthodeLes patients (n = 30, moyenne de 73 ans, limites de 65–86 ans) opérés pour cystoscopie ou hystéroscopie, ont été randomisés à l’insu d’un observateur pour une anesthésie avec propofol ou sévoflurane. Les changements aux tests neuropsychologiques (test Stroop, test modifié de remémoration de mots) ont été notés 24 h après l’opération et comparés à ceux de sujets témoins appariés selon l’âge (n = 15) au moyen de l’analyse de l’écart réduit. On a aussi noté les changements de niveaux de protéines S- 100ß et d’énolase neurospécifique.RésultatsLe DCPO était présent chez 7/15 [47% (intervalle de confiance de 95% (IC) 21 à 72%)] patients qui ont reçu le propofol et chez 7/15 [47%(ICde95% 21 à 72%)] patients qui ont reçu le sévoflurane, comparativement à 1/15 [7% (IC de 95% 6 a 19%)] témoins, P = 0,03. Les niveaux de protéines S- 100ß et d’énolase neurospécifique n’étaient pas significativement différents avant et après l’opération sous anesthésie.ConclusionLe premier jour après une opération mineure, l’incidence de DCPO chez les patients âgés est plus élevée qu’on ne le rapportait auparavant sept jours après une intervention majeure. Elle est augmentée avec le propofol et le sévoflurane, en comparaison avec des témoins du même âge. Les niveaux de protéines S- 100ß et d’énolase neurospécifique ne sont pas modifiés par la technique anesthésique.

Improving the working relationship between doctors and pharmacists: is inter-professional education the answer?

Despite their common history, there are many cultural, attitudinal and practical differences between the professions of medicine and pharmacy that ultimately influence patient care and health outcomes. While poor communication between doctors and pharmacists is a major cause of medical errors, it is clear that effective, deliberate doctor-pharmacist collaboration within certain clinical settings significantly improves patient care. This may be particularly true for those patients with chronic illnesses and/or requiring regular medication reviews. Moreover, in hospitals, clinical and antibiotic pharmacists are successfully influencing prescribing and infection control policy. Under the new Irish Pharmacy Act (2007), pharmacists are legally obliged to provide pharmaceutical care to their patients, thus fulfilling a more patient-centred role than their traditional ‘dispensing’ one. However, meeting this obligation relies on the existence of good doctor-pharmacist working relationships, such that inter-disciplinary teamwork in monitoring patients becomes the norm in all healthcare settings. As discussed here, efforts to improve these relationships must focus on the strategic introduction of agreed changes in working practices between the two professions and on educational aspects of pharmaceutical care. For example, standardized education of doctors/medical students such that they learn to prescribe in an optimal manner and ongoing inter-professional education of doctors and pharmacists in therapeutics, are likely to be of paramount importance. Here, insights into the types of factors that help or hinder the improvement of these working relationships and the importance of education and agreed working practices in defining the separate but inter-dependent professions of pharmacy and medicine are reviewed and discussed.

Curcumin-induced degradation of PKCδ is associated with enhanced dentate NCAM PSA expression and spatial learning in adult and aged Wistar rats

Polysialylation of the neural cell adhesion molecule (NCAM PSA) is necessary for the consolidation processes of hippocampus-based learning. Previously, we have found inhibition of protein kinase C delta (PKCdelta) to be associated with increased polysialyltransferase (PST) activity, suggesting inhibitors of this kinase might ameliorate cognitive deficits. Using a rottlerin template, a drug previously considered an inhibitor of PKCdelta, we searched the Compounds Available for Purchase (CAP) database with the Accelrys((R)) Catalyst programme for structurally similar molecules and, using the available crystal structure of the phorbol-binding domain of PKCdelta, found that diferuloylmethane (curcumin) docked effectively into the phorbol site. Curcumin increased NCAM PSA expression in cultured neuro-2A neuroblastoma cells and this was inversely related to PKCdelta protein expression. Curcumin did not directly inhibit PKCdelta activity but formed a tight complex with the enzyme. With increasing doses of curcumin, the Tyr(131) residue of PKCdelta, which is known to direct its degradation, became progressively phosphorylated and this was associated with numerous Tyr(131)-phospho-PKCdelta fragments. Chronic administration of curcumin in vivo also increased the frequency of polysialylated cells in the dentate infragranular zone and significantly improved the acquisition and consolidation of a water maze spatial learning paradigm in both adult and aged cohorts of Wistar rats. These results further confirm the role of PKCdelta in regulating PST and NCAM PSA expression and provide evidence that drug modulation of this system enhances the process of memory consolidation.

The selective 5-HT6 receptor antagonists SB-271046 and SB-399885 potentiate NCAM PSA immunolabeling of dentate granule cells, but not neurogenesis, in the hippocampal formation of mature Wistar rats

While there is now substantial evidence that 5-HT(6) antagonism leads to significantly improved cognitive ability, the mechanism(s) and/or pathway(s) involved are poorly understood. We have evaluated the consequence of chronic administration of the 5-HT(6) receptor antagonists SB-271046 and SB-399885 on neural cell adhesion molecule polysialylation state (NCAM PSA), a neuroplastic mechanism necessary for memory consolidation. Quantitative analysis of NCAM PSA immunopositive neurons in the dentate gyrus of drug-treated animals revealed a dose-dependent increase in polysialylated cell frequency following treatment with both SB-271046 and SB-399885. These effects could not be attributed to increased neurogenesis, as no difference in the rate of bromodeoxyuridine incorporation was apparent between the control and drug-treated groups. A substantial increase in the frequency of polysialylated cells in layer II of the entorhinal and perirhinal cortices was also observed, brain regions not previously associated with neurogenesis. Chronic treatment with SB-271046 or SB-399885 also significantly increased the activation of dentate polysialylation that is specific to learning. This effect does not occur with other cognition-enhancing drugs, such as tacrine, and this action potentially differentiates 5-HT(6) receptor antagonism as an unique neuroplastic mechanism for cognitive processes which may slow or reverse age/neurodegenerative related memory deficits.

Pentyl-4-yn-valproic acid enhances both spatial and avoidance learning and attenuates age-related NCAM-mediated neuroplastic decline within the rat medial temporal lobe

2‐N‐Pentyl‐4‐pentynoic acid [pentyl‐4‐yn‐valproic acid (VPA)] is an analogue of valproic acid that induces neuritogenesis and increases neural cell adhesion molecule (NCAM) prevalence in cultured neural cells. As memory consolidation involves synapse growth, aided by cell adhesion molecule function, we determined whether or not pentyl‐4‐yn‐VPA had cognition‐enhancing properties. Pentyl‐4‐yn‐VPA (16–85 mg/kg) significantly improved water maze learning and task retention when given prior to each training session. Acute administration of pentyl‐4‐yn‐VPA also influenced memory consolidation processes as, when given at 3 h post‐passive avoidance training, the amnesia induced by scopolamine given 6 h post‐training was prevented in a dose‐dependent manner. Chronic administration of pentyl‐4‐yn‐VPA (16.8 or 50.4 mg/kg) also significantly reduced escape latencies in the water maze task, 24 h following the last drug administration. This improved spatial learning was accompanied by enhanced neuroplasticity as the expression of NCAM polysialylated neurons in the infragranular zone of the dentate gyrus and in layer II of the perirhinal and piriform cortex was increased significantly following chronic drug treatment. The cognition‐enhancing qualities of pentyl‐4‐yn‐VPA, combined with its ability to attenuate the age‐related loss of the NCAM polysialylation state, suggest that it may effectively slow the onset of cognitive decline.

Protein kinase C delta regulates neural cell adhesion molecule polysialylation state in the rat brain

Polysialylation of neural cell adhesion molecule (NCAM PSA) modulates cell–cell homophilic binding and signalling during brain development and the remodelling of discrete brain regions in the adult. Following learning, a transient increase in the frequency of polysialylated neurones occurs in the dentate gyrus of the hippocampal formation, and this has been correlated with the selective retention and/or elimination of synapses that are transiently overproduced during memory consolidation. We now demonstrate that protein kinase C delta (PKCδ) negatively regulates polysialyltransferase activity in the rat brain during development and also in the hippocampus during memory consolidation, where its down‐regulation in the Golgi membrane fraction coincides with the transient increase in NCAM PSA expression. Decreased expression of PKCδ was also observed in the hippocampus of rats reared in a complex environment and this directly contrasted the significant increase in frequency of hippocampal polysialylated neurones observed in these animals. These effects were isoform‐specific as no change in total PKC enzyme activity was detected during memory consolidation and complex environment rearing had no effect on the hippocampal expression of PKCα, β, γ or ε. By sequential immunoprecipitation and immunoblot analysis, phosphorylation of polysialyltransferase protein(s) was (were) demonstrated to occur on both serine and tyrosine residues and this was associated with decreased enzyme activity. Moreover, a similar experimental approach revealed the degree of PKCδ co‐precipitation with polysialyltransferase protein(s) to be inversely correlated with polysialyltransferase activity. These findings support in vitro evidence indicating PKCδ to regulate polysialyltransferase activity and NCAM polysialylation state.

Antiproliferative action of valproate is associated with aberrant expression and nuclear translocation of cyclin D3 during the C6 glioma G1 phase

Cell cycle progression is tightly regulated by cyclins, cyclin‐dependent kinases (cdks) and related inhibitory phophatases. Here, we employed mitotic selection to synchronize the C6 glioma cell cycle at the start of the G1 phase and mapped the temporal regulation of selected cyclins, cdks and inhibitory proteins throughout the 12 h of G1 by immunoblot analysis. The D‐type cyclins, D3 and D1, were differentially expressed during the C6 glioma G1 phase. Cyclin D1 was up‐regulated in the mid‐G1 phase (4–6 h) while cyclin D3 expression emerged only in late G1 (9–12 h). The influence of the anticonvulsant agent valproic acid (VPA) on expression of cyclins and related proteins was determined, since its teratogenic potency has been linked to cell cycle arrest in the mid‐G1 phase. Exposure of C6 glioma to VPA induced a marked up‐regulation of cyclin D3 and decreased expression of the proliferating cell nuclear antigen. In synchronized cell populations, increased expression of cyclin D3 by VPA was detected in the mid‐G1 phase (3–5 h). Immunocytochemical localization demonstrated rapid intracellular translocation of cyclin D3 to the nucleus following VPA exposure, suggesting that VPA‐induced cell cycle arrest may be mediated by precocious activation of cyclin D3 in the G1 phase.

Differential effects of serum from patients administered distinct anaesthetic techniques on apoptosis in breast cancer cells in vitro: a pilot study

BACKGROUND In vitro and retrospective clinical studies suggest an association between anaesthetic technique during primary breast cancer surgery and cancer outcome. Apoptosis is an important step in the mechanism of breast cancer metastasis, but whether it is influenced by anaesthetic technique is unknown. Using serum from breast cancer surgery patients randomized to receive distinct anaesthetic techniques, we investigated its effect on apoptosis in oestrogen receptor (ER)-negative breast cancer cells in vitro. METHODS Women with biopsy-proven breast cancer were randomized to receive either propofol general anaesthesia with paravertebral analgesia (PPA) or standard sevoflurane general anaesthesia with opioid analgesia (SGA) in an ongoing, prospective clinical trial (NCT 00418457). Serum from a randomly selected subset of these patients (10 PPA and 10 SGA) who had donated 20 ml venous blood immediately before anaesthetic induction and at 1 h after operation was exposed to ER-negative MDA-MB-231 cells. Apoptosis was measured using ApoLive-Glo Multiplex Assay™. RESULTS Exposure of MDA-MB-231 cells to postoperative serum of PPA patients resulted in higher luminescence ratio (apoptosis) than SGA patients, median (25-75%), 0.40 (0.35-0.43) compared with 0.22 (0.21-0.30), respectively (P=0.001). The luminescence ratio of postoperative serum from SGA was reduced compared with preoperative SGA 0.22 (0.21-0.30) compared with 0.3 (0.25-0.35) (P=0.045). CONCLUSIONS Serum from patients given sevoflurane anaesthesia and opioids for primary breast cancer surgery reduces apoptosis in ER-negative breast cancer cells to a greater extent than serum from patients given propofol-paravertebral anaesthesia. Anaesthetic technique might affect the serum milieu in a manner that impacts cancer cell apoptosis, and thereby tumour metastasis.