The use of infliximab in X-linked agammaglobulinaemia associated enteropathy.

Granulomatous small bowel enteropathy is an unusual presentation associated with X-linked agammaglobulinaemia. We present a rare case of this condition that was further complicated by an enterocutaneous fistula and report our experience managing this condition successfully with infliximab, which has not been documented in the literature previously.

An internal carotid artery aneurysm presenting with dysarthria.

A 72-year-old woman presented to her general practitioner with a 4-week history of right neck swelling. Clinical examination elicited a pulsatile mass consistent with a carotid artery aneurysm. Five days later the patient noticed her tongue movements had become awkward with associated dysarthria. Computed tomography confirmed a 4cm internal carotid artery aneurysm arising just distally to the carotid bifurcation. She proceeded to transfemoral diagnostic carotid angiography. Balloon occlusion of the right internal carotid artery origin was performed for a ten-minute period without any neurological deficit. The decision was taken to proceed to surgical ligation of the origin of the internal carotid artery. Her symptoms of dysarthria have resolved.

Common bile duct stones: an unusual case of diarrhoea through a mucous fistula.

We present a very unusual case of diarrhoea in a 77-year-old man. He had a previously complicated surgical history, with a loop ileostomy and a colonic mucous fistula. He developed a sudden onset of diarrhoea from his mucous fistula. A contrast enema suggested a cholecystocolonic fistula and subsequent computed tomography demonstrated a common bile duct stone caused a degree of obstruction. The patient was treated successfully by endoscopic retrograde cholangiopancreatography and stone extraction. This case demonstrated the role that contrast enema may still play in unusual cases of diarrhoea.

An acute groin lump: surgical exploration is not always the best option.

This is a case of a very unusual cause of an acute groin lump in a 71-year-old woman that was presumed initially to either be an incisional or inguinal hernia. However, with subsequent computed tomography it was shown to be thrombophlebitis of collateral vessels secondary to a previous deep vein thrombosis. This case demonstrates how surgical exploration of acute groin lumps is not without its dangers.

Orexin-A, an hypothalamic peptide with analgesic properties.

The hypothalamic peptide orexin-A and the orexin-1 receptor are localized in areas of the brain and spinal cord associated with nociceptive processing. In the present study, localization was confirmed in the spinal cord and demonstrated in the dorsal root ganglion for both orexin-A and the orexin-1 receptor. The link with nociception was extended when orexin-A was shown to be analgesic when given i.v. but not s.c. in mouse and rat models of nociception and hyperalgesia. The efficacy of orexin-A was similar to that of morphine in the 50 degrees C hotplate test and the carrageenan-induced thermal hyperalgesia test. However, involvement of the opiate system in these effects was ruled out as they were blocked by the orexin-1 receptor antagonist SB-334867 but not naloxone. Orexin-1 receptor antagonists had no effect in acute nociceptive tests but under particular inflammatory conditions were pro-hyperalgesic, suggesting a tonic inhibitory orexin drive in these circumstances. These data demonstrate that the orexinergic system has a potential role in the modulation of nociceptive transmission.

Inhibition of inflammation-induced thermal hypersensitivity by sumatriptan through activation of 5-HT(1B/1D) receptors.

Migraine is effectively treated by drugs acting via 5-HT(1B/1D) receptors; however, the antinociceptive effects of such agents have not been fully investigated, particularly in models in which sensitization may be present. The aim of these studies was to evaluate the effects of the 5-HT(1B/1D) receptor agonist sumatriptan in specific models of pain states: a mouse model of inflammation-induced thermal hyperalgesia and a rat model of nerve injury-induced thermal hyperalgesia. In female mice, following intraplantar injection of carrageenan 225 min earlier, sumatriptan (300 microg/kg intraperitoneally; i.p.) increased paw withdrawal latency (PWL) from 3.1 +/- 0.4 s in the saline group to 5.6 +/- 0.9 s, measured 240 min postcarrageenan (P < 0.05 ANOVA followed by post hoc Dunnett's test). A similar effect was seen in male mice. Sumatriptan was also effective in male mice when given i.p. and subcutaneously 15 min precarrageenan, with a maximum effect at 30 microg/kg (i.p. latency 7.4 +/- 1.3 s compared to saline group, 2.6 +/- 0.7 s; i.v. latency 5.9 +/- 0.8 s compared to saline group, 2.9 +/- 0.3 s; P < 0.05 ANOVA followed by post hoc Dunnett's test). The number of mice required to give a response that could be reliably attributed to sumatriptan (number needed to treat) was calculated using discriminant analysis and found to be 2.6. The ability of sumatriptan to attenuate the carrageenan-induced reduction in PWL was blocked by the mixed 5-HT(1B/1D) receptor antagonist GR-127935 (3 mg/kg i.p.) but not by the 5-HT(1B) receptor antagonist SB-224289 (10 mg/kg i.p.). Sumatriptan had no effect on thermal hyperalgesia induced by sciatic nerve ligation in the rat at any time point. These data demonstrate that sumatriptan attenuates the hypersensitivity to noxious thermal stimuli induced by intraplantar carrageenan.

Carrageenan-induced thermal hyperalgesia in the mouse: role of nerve growth factor and the mitogen-activated protein kinase pathway.

NGF is an important link between inflammation and hyperalgesia and interacts with many different mediators of inflammation, including the MAPK signaling pathway. In these studies, carrageenan-induced thermal hyperalgesia was evaluated in the mouse and the role of NGF and the MAPK pathway investigated. Carrageenan induced a time-dependent inflammation and thermal hyperalgesia, which was maximal 4 h post administration. Both indomethacin (0.3, 1.0 and 10 mg/kg s.c., 30 min pre-carrageenan) and morphine (0.4, 1.2, 4.0 mg/kg; s.c., 30 min pre-hyperalgesia measurement) significantly inhibited carrageenan-induced thermal hyperalgesia and indomethicin inhibited paw inflammation, demonstrating the model as suitable for the assessment of anti-hyperalgesic and anti-inflammatory agents. Anti-NGF (0.67 mg/kg sc, 60 min pre-carrageenan) produced a significant inhibition of thermal hyperalgesia, but not inflammation. NGF itself produced a time-dependent hyperalgesia, but not inflammation, following intraplantar injection. The specific MAPK pathway inhibitor, PD98059 (0.1, 0.3 and 1 mg/kg sc, 30 min pre-carrageenan) significantly inhibited carrageenan-induced hyperalgesia, but not inflammation. These data demonstrate a role for both NGF and the MAPK signaling pathway in the production of thermal hyperalgesia, but not inflammation, in the mouse.

Vanilloid receptor-1 is essential for inflammatory thermal hyperalgesia.

The vanilloid receptor-1 (VR1) is a ligand-gated, non-selective cation channel expressed predominantly by sensory neurons. VR1 responds to noxious stimuli including capsaicin, the pungent component of chilli peppers, heat and extracellular acidification, and it is able to integrate simultaneous exposure to these stimuli. These findings and research linking capsaicin with nociceptive behaviours (that is, responses to painful stimuli in animals have led to VR1 being considered as important for pain sensation. Here we have disrupted the mouse VR1 gene using standard gene targeting techniques. Small diameter dorsal root ganglion neurons isolated from VR1-null mice lacked many of the capsaicin-, acid- and heat-gated responses that have been previously well characterized in small diameter dorsal root ganglion neurons from various species. Furthermore, although the VR1-null mice appeared normal in a wide range of behavioural tests, including responses to acute noxious thermal stimuli, their ability to develop carrageenan-induced thermal hyperalgesia was completely absent. We conclude that VR1 is required for inflammatory sensitization to noxious thermal stimuli but also that alternative mechanisms are sufficient for normal sensation of noxious heat.

Further studies of the antiemetic activity of granisetron against whole body X-irradiation or cisplatin-induced emesis in the ferret.

In ferrets, the highly selective 5-HT3 receptor antagonist, granisetron, abolished or reduced emesis induced by cisplatin (10 mg/kg i.v.) or whole body X-irradiation (50 Gy in 10.4 min) in a dose-dependent manner when administered by a variety of routes (intravenous, per os, subcutaneous, intramuscular). Complete protection from vomiting and retching was achieved with 0.5 mg/kg i.v. or p.o. granisetron. Granisetron (0.5 mg/kg i.v.) was also effective when given 6 h before cisplatin, completely protecting 50% of ferrets for a total of 10 h. Following repeat dosing, for either 4 days i.v. or 10 days p.o. before emetic challenge, granisetron (0.5 mg/kg) still retained its antiemetic activity on the 5th or 11th day. Prior treatment with cyclophosphamide (80 mg/kg i.v.) resulted in a significantly shorter time to the onset of vomiting after exposure to X-irradiation. Granisetron, but not saline, abolished vomiting and nausea when given as intervention after this combined emetic regimen. These results show that granisetron has potential flexibility for administration via a variety of different routes and also a long duration of action when used as an antiemetic against a wide range of cytostatic agents.

The antiemetic activity of granisetron against cytostatic-treatment-induced emesis in 10- to 13-week-old ferrets.

The antiemetic activity of granisetron was examined in ferrets aged 10-13 weeks. Emesis was induced by exposure to either whole-body X-irradiation (50 Gy over 10.4 min) or cyclophosphamide (80 mg/kg i.v.) plus doxorubicin (6 mg/kg i.v.). Following exposure to whole-body X-irradiation, the young ferrets vomited with a similar latency to vomit and severity of emesis to that shown by adult animals. Granisetron (0.5 mg/kg i.v.) significantly reduced (P < or = 0.05) the number of vomits and retches and two out of four animals were completely protected. Following injection of cyclophosphamide and doxorubicin, the young ferrets showed a reduced emetic response compared to adult animals. Following a dose of granisetron (0.5 mg/kg i.v.), only one out of four ferrets vomited compared to four out of four in the control group. Further experiments showed that cisplatin (12.5 mg/kg i.v.) was unable to induce vomiting in the young ferret (n = 2). Granisetron (0.5 mg/kg i.v.) was well tolerated by the young ferret and was able to reduce significantly or completely abolish emesis induced by cytostatic treatment. The data support the use of granisetron in pediatric patients and clinical trials are currently underway in this patient population.

Are all 5-HT3 receptor antagonists the same?

A number of 5-HT3 receptor antagonists are currently in clinical development as antiemetics. In this paper we focus on two of these antagonists, granisetron and ondansetron, and compare their antimetic activity against cisplatin (10 mg/kg i.v.)- or whole body X-irradiation (200 rads)-induced emesis in the conscious ferret. The results presented here have been discussed in the light of the recently published literature. Our data suggest that in comparison to ondansetron, granisetron is a more potent, longer acting and pharmacologically "cleaner" compound with a more conventional dose-response profile. The possible impact of these features upon the performance of these compounds in the clinic is discussed particularly with respect to dosing regimens and clinical efficacy. Differences appear to be emerging between granisetron and ondansetron in both these respects, although a direct head-to-head clinical comparison has yet to be carried out. This would involve studies monitoring a sufficiently high number of patients receiving severely emetogenic regimes to allow real clinical differences to be detected with the appropriate statistical power.

Emerging differences between 5-HT3 receptor antagonists.

A brief review is presented of some recently described 5-HT3 receptor antagonists. These antagonists are primarily targeted for use as anti-emetics. However, evidence is emerging that there are differences in their basic pharmacology. This evidence is reviewed in terms of the selectivity of the antagonists in binding studies and also of their efficacy in emesis and gastric emptying. The possibility that these differences may translate into meaningful clinical differences between the available 5-HT3 receptor antagonists in their use as anti-emetics is also discussed.