Blockade of Pannexin-1 Channels and Purinergic P2X7 Receptors Shows Protective Effects Against Cytokines-Induced Colitis of Human Colonic Mucosa.

Introduction: The pannexin-1 (Panx1) channels are found in many cell types, and ATP released from these channels can act on nearby cells activating purinergic P2X7 receptors (P2X7R) which lead to inflammation. Although Panx1 and P2X7R are implicated in the process of inflammation and cell death, few studies have looked at the role they play in inflammatory bowel disease in human. Hence, the aim of the present study was to investigate the function of Panx1 and P2X7R in an ex vivo colitis model developed from human colonic mucosal explants. Materials and Methods: Healthy human colonic mucosal strips (4 × 10 mm) were incubated in carbogenated culture medium at 37°C for 16 h. Proinflammatory cytokines TNFα and IL-1ß (each 10 ng/mL) were used to induce colitis in mucosal strips, and the effects of Panx1 and P2X7R on cytokines-induced tissue damage were determined in the presence of the Panx1 channel blocker 10Panx1 (100 µM) and P2X7R antagonist A438079 (100 µM). The effects of 10Panx1 and A438079 on cytokines-enhanced epithelial permeability were also studied using Caco-2 cells. Results: Histological staining showed that the mucosal strips had severe structural damage in the cytokines-only group but not in the incubation-control group (P < 0.01). Compared to the cytokines-only group, crypt damage was significantly decreased in groups receiving cytokines with inhibitors (10Panx1, A438079, or 10Panx1 + A438079, P < 0.05). The immunoreactive signals of tight junction protein zonula occludens-1 (ZO-1) were abundant in all control tissues but were significantly disrupted and lost in the cytokines-only group (P < 0.01). The diminished ZO-1 immunoreactivity induced by cytokines was prevented in the presence of 10Panx1 (P = 0.04). Likewise, 10Panx1 significantly attenuated the cytokines-evoked increase in paracellular permeability of Caco-2 cells. Although the inhibition of P2X7R activity by A438079 diminished cytokines-induced crypt damage, its effect on the maintenance of ZO-1 immunoreactivity and Caco-2 epithelial cell integrity was less evident. Conclusion: The blockade of Panx1 and P2X7R reduced the inflammatory cytokines-induced crypt damage, loss of tight junctions and increase in cell permeability. Thus, Panx1 and P2X7R may have roles in causing mucosal damage, a common clinical feature of inflammatory bowel disease.

Adult liver transplantation in the congenital absence of inferior vena cava.

Whereas congenital absence of inferior vena cava observed in paediatric population more often than not, as an isolated or syndromic variety, this is seldom encountered in adult liver transplant recipients. There appear few sporadic reports in the literature on experience of such anomaly in adults. Given the rarity of situation, surprising encounters of such anomalies may pose challenge to the unprepared transplant surgeon and unfavourable outcomes may even have resulted in under-reportage of this condition. In this brief report we document our recent experience with two such cases and this is supplemented with extensive reference to the literature on classification of such anomalies with the endeavour to document implications of such in the adult liver transplant setting.

Pannexin-2 is expressed in the human colon with extensive localization in the enteric nervous system.

BACKGROUND: Pannexin-2 (Panx2) is a member of the novel group of membrane spanning protein channels present in the central nervous system. Limited studies have examined Panx2 in the intestine, where it may have important physiological roles. The present study characterized Panx2 expression and localization in the human colon in health and disease states. METHODS: Immunofluorescence determined Panx2 localization and co-localization, and quantitative real-time PCR and Western blot determined gene and protein expression in ulcerative colitis (UC), Crohn's disease (CD), and control human colon. KEY RESULTS: Panx2 was widely expressed in myenteric and submucosal ganglia, particularly in the cytoplasm of neurons. Panx2 was also expressed on smooth muscle of the muscularis and blood vessels, some non-lymphoid leukocytes, mast cells, and mucosal epithelial cells. Co-localization of Panx2 occurred with ß-tubulin, neuronal nitric oxide synthase, substance P, vesicular acetylcholine transporter, and calcitonin gene-related peptide, indicating widespread Panx2 expression in extrinsic and intrinsic neurons. Molecular studies revealed a 3.4-fold higher level of Panx2 mRNA in ascending compared to sigmoid muscularis (p < 0.05), despite similar protein levels. Similarly, UC muscularis showed a 35-fold up-regulation in Panx2 mRNA, but not in protein (p < 0.05). CONCLUSIONS & INFERENCES: Here, we demonstrated the dense expression of Panx2 in the enteric nervous system and the co-localization of Panx2 with a spectrum of neuronal markers, indicating that Panx2 may be involved in mediating neurotransmission in the colon. The substantial increase in Panx2 mRNA in UC muscle but not protein suggests that the Panx2 translation process may be disrupted in UC.

Distinct differences in tachykinin gene expression in ulcerative colitis, Crohn's disease and diverticular disease: a role for hemokinin-1?

BACKGROUND: In the intestine, the tachykinins substance P (SP) and neurokinin A (NKA) are found in neurons and have key roles in motility, secretion, and immune functions. A new tachykinin, hemokinin (HK-1), has been identified in non-neuronal cells in recent years and its role in intestinal inflammation is unclear. We aimed to examine the expression of genes encoding tachykinin peptides and receptors in colon from patients with ulcerative colitis (UC), Crohn's disease (CD), and acute diverticular disease (DD). METHODS: Human colon segments were dissected into mucosa and muscle, and evaluated for tachykinin and tachykinin receptor gene expression by real-time PCR. KEY RESULTS: In UC mucosa, the TAC4 gene (encoding HK-1) was 10-fold more abundant than in control mucosa (P < 0.01). Similarly, TAC1 (encoding SP and NKA) and TACR1 (encoding NK1 receptor) displayed 6-fold and 12-fold upregulation, respectively, in UC mucosa, but no change occurred in UC muscle. In contrast to UC, no difference was observed for any tachykinin genes in CD mucosa. In CD muscle, expression of TAC1 (P < 0.01), TAC4 and TACR1 (both P < 0.05) were moderately upregulated. In DD, there was a decrease in TACR1 (P < 0.05), and TACR2 (encoding NK2 receptor, P < 0.0001) in muscle compared with control. Histological staining showed increased collagen fibers between muscle bundles in DD smooth muscle. CONCLUSIONS & INFERENCES: We provide evidence for the first time that HK-1, like SP, may be involved in the pathophysiology of inflammatory bowel disease. Distinctly different expression patterns of tachykinin-related genes occur in UC, CD and DD.

Surveillance-detected hepatic metastases from colorectal cancer had a survival advantage in seven-year follow-up.

PURPOSE: Colorectal cancer is a common cause of cancer-related death. The liver is the most common site of distant metastases and the most amenable to potentially curative surgery. The aim of this study was to determine whether hepatic metastases detected by surveillance following colonic resection were associated with higher resectability rates and to determine whether there was any impact on survival rates. METHODS: A retrospective study of 211 patients who presented to the liver unit between February 1990 and July 1996 with hepatic metastases following colonic resection for adenocarcinoma was performed. Patients were divided into two groups: Group A (n = 154), hepatic metastases diagnosed by carcinoembryonic antigen or by radiology; and Group B (n = 57), patients with symptomatic presentation. RESULTS: Potentially curative operations were possible in 51.3 percent (79/154) of Group A patients and 28.1 percent (16/57) of Group B patients (P = 0.0043, chi-squared test). In Groups A and B, 24 percent (37/154) and 43.9 percent (25/57) of patients, respectively, were inoperable. The three-year and five-year survival rates after detection of liver metastases were 26.8 percent (41/153) in Group A and 12.5 percent (7/56) in Group B, and 5.9 percent (9/153) in Group A and 8.9 percent (5/56) in Group B, respectively. Log-rank analysis resulted in P = 0.05, Breslow test in P = 0.01. CONCLUSION: Our study shows that patients with hepatic metastases from colorectal cancer detected by follow-up were significantly more likely to have a potentially curative operation. Our medium-term survival data show a statistically significant survival benefit in patients with surveillance-detected metastases.

Fibrolamellar hepatocellular carcinoma in pregnancy.

BACKGROUND: Hepatocellular carcinoma (HCC) is rare in pregnancy but can enlarge rapidly under these circumstances. CASE OUTLINE: A 25-year-old woman was diagnosed with HCC of fibrolamellar type immediately post-partum. One year after liver resection the patient remains well. DISCUSSION: This is only the second report of fibrolamellar carcinoma occurring in pregnancy. Other types of hepatocellular carcinoma in pregnancy have generally demonstrated a poor outcome, probably secondary to hormonal changes and increased liver vascularity.

Renal impairment in hepatic cryotherapy.

Cryoshock is a syndrome of coagulopathy, renal, and pulmonary injury following cryotherapy, and its etiology is unknown. The aim of this study was to assess the impact of hepatic cryotherapy on renal function, and whether this effect is related to volume of cryotherapy, and to identify any predictors of renal impairment in patients who undergo cryotherapy. A retrospective analysis of all patients with primary or secondary hepatic malignancy treated with cryotherapy from April 1990 to October 1996 was conducted. Ten of 204 patients with renal impairment (elevation in creatinine of greater than 0.02 mmol/L for more than 2 days postprocedure) were identified. One patient has postoperative pancreatitis with late renal impairment (20 days) and was excluded. The severity of renal impairment was usually modest (mean rise in creatinine of 0.31 mmol/L; SD, 0.19). Two patients required temporary hemodialysis. Only one patient, who had significant cardiac disease, had associated pulmonary injury and shock. Demographic data in both groups were comparable, except for a trend toward more noncolorectal cancer patients in the renal impairment group (4/9 vs 33/194). Patients in the renal impairment group had a greater number of lesions than those of the nonrenal impairment group (3.4 vs 2.1, p < 0.01), as well as larger lesion diameter (2.9 vs 1.9, p < 0.01), increased freezing time (74.7 vs 44.3, p < 0.01), and a higher aspartate transaminase (AST) (2254 vs 1157, p < 0.01). This study suggests that renal impairment is more likely to be seen in patients undergoing more extensive cryotherapy. The number and diameter of lesions together with AST data link renal injury with magnitude of liver injury--all renal impairment patients had an AST > 1000, compared with only 28% of patients who did not.

Emergency femoral arteriography in lower limb vascular trauma.

There are difficulties in obtaining emergency arteriographic evaluation in lower limb vascular trauma even in the best centres in the world. Ten emergency room arteriograms were performed at the new Accident Service of the General Hospital, Colombo from February to October 1992 by the vascular team, using a venous cannula and improvised tubing systems. The indications were, absence of distal pulses with closed injury to the limb, previous attempts at repair, injury to the limb at more than one site and multiple shrapnel injury. A traumatic arteriovenous communication was shown in one of the arteriograms. Unnecessary exploration of the artery was prevented by the demonstration of a patent femoropopliteal segment in two cases. The average delay caused by this procedure was less than one hour, which compares well with centres in the West. Provision of an arteriogram kit at the Accident Service will help to overcome practical problems.