Prokineticin 1 inhibits spontaneous giant contractions in the murine proximal colon through nitric oxide release

Prokineticins are novel peptides with reported effects on gastrointestinal contractility. Prokineticin actions are mediated by distinct prokineticin receptors (PKR1 and PKR2). This study investigated the role of prokineticin 1 in colonic contractility as well as sites of expression of its receptor in the mouse proximal colon by immunohistochemistry and confocal microscopy. Prokineticin 1 suppressed giant contractions in circular muscle. The inhibitory effect of prokineticin 1 on giant contractions was blocked by the nitric oxide synthase (NOS) inhibitor Nomega-nitro-L-arginine methyl ester (L-NAME). In vitro, prokineticin 1 stimulated nitric oxide release from longitudinal muscle-myenteric plexus cultures. This effect was blocked by L-NAME. PKR1 is expressed on myenteric plexus neurons and colocalizes with a small subset of nNOS expressing neurons. This study suggests that PKR1 mediates an inhibitory effect in vitro, most likely through direct or indirect stimulation of nitric oxide release. PKR1 and its natural ligand, prokineticin 1 may be important for modulation of colonic motility.

The proteinase-activated receptor 2 is involved in nociception

The proteinase-activated receptor 2 is expressed on a subset of primary afferent neurons and may participate in the neurogenic component of inflammation. We hypothesized that this receptor may also play a role in neuronal sensitization and contribute to the pathogenesis of pain in inflammatory conditions such as pancreatitis. Using a specific proteinase-activated receptor 2 activating peptide, we found evidence of such sensitization in vitro in the form of enhanced capsaicin- and KCl-evoked release of calcitonin gene-related peptide, a marker for nociceptive signaling. We then demonstrated that injection of the proteinase-activated receptor 2 activating peptide into the pancreatic duct can activate and sensitize pancreas-specific afferent neurons in vivo, as measured by Fos expression in the dorsal horn of the spinal cord. These observations suggest that proteinase-activated receptor 2 contributes to nociceptive signaling and may provide a novel link between inflammation and pain.

Pharmacologic therapy in treating achalasia

This article focuses on the different pharmacologic treatments for achalasia. Most smooth muscle relaxants such as nitrates and calcium antagonists are temporizing at best. Botulinum toxin, acting at the neuronal level, is effective in two thirds of the patients and has a duration of action of several months. It may be particularly suitable for the elderly or high-risk patient. The mechanism of action and efficacy of the different drugs are discussed in detail.

Gallstones

At the turn of the millennium, significant advances continue to be made into the epidemiology and pathophysiology of gallstone disease. The NHANES III study, the largest American population-based study of gallstone disease, estimated that more than 20 million Americans have undergone gallbladder surgery or currently have gallstones. Insulin resistance may be an independent risk factor for gallstone disease.Cholecystokinin receptors may be responsible for the altered motility of the gallbladder smooth muscle, and mucin may play an underestimated role as a pronucleating factor. For the first time, researchers have been able to directly observe cholesterol crystallization in human bile. Improved understanding of the multiple factors involved in the pathogenesis of gallstone disease should lead to new therapeutic and preventive strategies.

Achalasia: treatment options revisited

The aim of all current forms of treatment of achalasia is to enable the patient to eat without disabling symptoms such as dysphagia, regurgitation, coughing or choking. Historically, this has been accomplished by mechanical disruption of the lower esophageal sphincter fibres, either by means of pneumatic dilation (PD) or by open surgical myotomy. The addition of laparoscopic myotomy and botulinum toxin (BTX) injection to the therapeutic armamentarium has triggered a recent series of reviews to determine the optimal therapeutic approach. Both PD and BTX have excellent short term (less than three months) efficacy in the majority of patients. New data have been published that suggest that PD and BTX (with repeat injections) can potentially obtain long term efficacy. PD is still considered the first-line treatment by most physicians; its main disadvantage is risk of perforation. BTX injection is evolving as an excellent, safe option for patients who are considered high risk for more invasive procedures. Laparoscopic myotomy with combined antireflux surgery is an increasingly attractive option in younger patients with achalasia, but long term follow-up studies are required to establish its efficacy and the potential for reflux-related sequelae.

Gallstones

This review summarizes the main advances made in the epidemiology, pathogenesis, and medical treatment of gallstone disease in the past year. Whether rapid weight reduction can precipitate gallstone formation is still debated. Phospholipase A(2)-II seems to play an interesting role in the pathogenesis of multiple cholesterol stone formation, and ursodeoxycholic acid may partially halt the formation of multiple cholesterol stones by mediating an anti-inflammatory effect on the gallbladder. Bacterial infections may contribute to gallstone formation, perhaps through secretion of biofilm. The combination of ursodeoxycholic acid and simvastatin for the resolution and prevention of gallstones is promising, but larger studies are needed.

Pain: the overlooked symptom in gastroparesis

OBJECTIVE

Abdominal pain has not been reported generally as a significant feature of the clinical presentation of patients with gastroparesis.

METHODS

Using a standardized questionnaire, we analyzed the clinical features of 28 consecutive patients referred with established or suspected gastroparesis over a 4-yr period. The diagnosis of gastroparesis was supported by abnormalities in gastric emptying studies (GES), electrogastrography (EGG), or upper endoscopy (EGD). Diagnostic tests were reviewed.

RESULTS

A total of 12 male (mean age 39.5 yr) and 18 female patients (mean age 39.6 yr) were included in this study. These patients had been symptomatic for an average of 37.8 months before their referral to our center. Seven of these patients had insulin-dependent diabetes. Idiopathic gastroparesis was present in more than half of the patients. The symptom profile of the 28 patients was as follows: nausea, 92.9%; abdominal pain, 89.3%; early satiety, 85.7%; and vomiting, 67.9%. The pain was described as burning, vague, or crampy in nature. Only 36% localized to the upper abdomen. In all, 60% of patients complained of postprandial pain, whereas 80% complained of nocturnal pain that interfered with their normal sleeping pattern. In general, pain responded poorly or not at all to prokinetic agents.

CONCLUSIONS

Nausea and abdominal pain are the most common complaints of patients with gastroparesis. In 80% of patients, GES and EGG correlated positively.

Botulinum toxin for spastic gastrointestinal disorders

Botulinum toxin (BTX) is one of the most potent inhibitors of acetylcholine from nerve endings, and this accounts for its toxic properties as well as its therapeutic application in a variety of neuromuscular syndromes. This review focuses on the growing use of BTX in the so-called 'spastic' disorders of the gastrointestinal tract. These include achalasia, for which the short-term efficacy of the intrasphincteric injection of BTX has been well established. However, because of the chronicity of this condition, repeated injections of the toxin may be required at regular intervals. In contrast, the relatively short duration of action may be an advantage in disorders such as chronic anal fissure, where the benefit of this therapy has now been demonstrated in hundreds of patients. There are many other sphincteric and non-sphincteric syndromes in the gut for which the efficacy of this agent is being actively tested. These include non-cardiac chest pain, post-operative pylorospasm and sphincter of Oddi dysfunction. Skeletal muscle sphincters, such as the upper oesophageal sphincter or the external anal sphincter/puborectalis muscle, may also be targeted, with good effect. In some of these conditions, the local injection of BTX may serve as a useful therapeutic trial, facilitating the decision to institute more invasive forms of therapy. The cumulative short-term experience with BTX in the gut to date suggests that it is a relatively simple and safe therapy. The use of BTX represents a novel approach for gastrointestinal motility disorders, and the rapidly expanding list of successful applications holds promise for a more widespread use of similar agents in the future. Additional studies on long-term outcome are eagerly awaited.

Asymmetric signal transduction in polarized ileal Na(+)-absorbing cells: carbachol activates brush-border but not basolateral-membrane PIP2-PLC and translocates PLC-gamma 1 only to the brush border

In ileal Na+ absorptive cells, carbachol inhibits NaCl absorption and its component brush-border Na+/H+ exchanger, acting via basolateral membrane (BLM) receptors. This carbachol effect involves brush-border but not BLM protein kinase C. In the present work we describe another asymmetric aspect of signal transduction in these epithelial cells, this time involving phosphatidylinositol 4,5-bisphosphate (PIP2)-specific phospholipase C (PLC). Thirty seconds and 1 min after carbachol treatment, brush-border PIP2-specific PLC activity increased, returning to control levels by 2.5 min. Involvement of brush-border tyrosine kinase(s) in this effect was suggested by inhibition of the carbachol effect on NaCl absorption by the tyrosine kinase inhibitor genistein, added to the mucosal but not the serosal surface. Luminal genistein pretreatment also prevented the carbachol-induced increase in brush-border PLC activity. In contrast, carbachol exposure did not change the BLM PIP2-specific PLC activity. Western analysis and immunoprecipitation demonstrated that PLC-gamma 1 is present in the brush border and that carbachol increases the PLC-gamma 1 amount in the brush border. Both the brush border and BLM contain PLC-beta 3 and a small amount of PLC-delta 1 but no PLC-beta 1, whereas BLM lacks detectable PLC-gamma 1. No change in PLC-beta 3 or PLC-delta 1 amount in the brush border occurred with carbachol exposure. No change in tyrosine phosphorylation of brush-border PLC-gamma 1 occurred with carbachol treatment. The Ca2+ ionophore A23187 did not alter PIP2-specific PLC activity in either the brush border or the BLM. These studies demonstrate that carbachol but not Ca2+ ionophore effects on brush-border NaCl absorption are associated with increases in brush-border but not BLM PIP2-specific PLC activity and in the amount of brush-border PLC-gamma 1, and involve tyrosine phosphorylation. This asymmetric aspect of epithelial signal transduction, together with the previous demonstration of localization of high-sensitivity IP3 stores to the apical membrane area in intestinal epithelial cells, shows that different aspects of signal transduction occur at the apical and basolateral membranes in epithelial and requires studies in both domains to define mechanisms of intracellular signalling.

NHE2 and NHE3 are human and rabbit intestinal brush-border proteins

Rabbit NHE2 and NHE3 are two epithelial isoform Na+/H+ exchangers (NHE), the messages for which are found predominantly and entirely, respectively, in renal, intestinal, and gastric mucosa. The current studies used Western analysis and immunohistochemistry to identify and characterize the apical vs. basolateral membrane distribution of NHE2 and NHE3 in intestinal epithelial cells. Based on Western analysis, NHE2 and NHE3 both are present in brush-border but not basolateral membranes of small intestine. Both NHE2 and NHE3 are 85-kDa proteins. Consistent with Western analysis, NHE2 and NHE3 are immunolocalired to the brush-border but not basolateral membranes of villus epithelial cells, but not goblet cells, in human jejunum and ileum and in surface epithelial cells in the ascending and descending colon and rectum. In addition, NHE2 and NHE3 are present in small amounts in the crypt cell brush border of human jejunum, ileum, ascending and descending colon, and rectum. In rabbit jejunum, ileum, and ascending colon, NHE2 and NHE3 are present in the brush border of epithelial and not goblet cells, again much more in the villus (small intestine)/ surface cells (colon) than the crypt. NHE2 but not NHE3 is present in the brush border of rabbit descending colon surface cells and in small amounts in crypt cells. NHE2 and NHE3 are both human and rabbit small intestinal and colonic epithelial cell brush-border Na+/H+ exchanger isoforms that colocalize in all intestinal segments except rabbit descending colon, which lacks NHE3.

Chromosome analysis of nine osteosarcomas

Although recurrent chromosome abnormalities have been identified in several histologic subtypes of sarcomas, no consistent rearrangement has yet been found in osteosarcomas. Cytogenetic analyses of nine cases of osteosarcoma are reported, including seven newly diagnosed tumors and two recurrent tumors. There were seven high-grade osteosarcomas, one periosteal osteosarcoma, and one well-differentiated sarcoma. All tumors were studied in short-term primary culture. Modal number ranged from near diploid to near triploid. Seven tumors had complex karyotypes with multiple structural abnormalities; two had only normal karyotypes. The retinoblastoma gene on chromosome 13 and the TP53 gene on chromosome 17 have been involved in osteosarcoma. Five tumors had loss of a whole copy of chromosome 13, and three of these also had a loss of a whole copy of chromosome 17. However, these losses were observed in the setting of numerous other chromosome losses. Numerous structural abnormalities were observed, many involving additions of unidentified material, unbalanced translocations, or deletions. Structural abnormalities with similar breakpoints involving 6q, 8q, 9q, and 14p were seen in two or three tumors each. When the tumors in this series were added to the 18 published cases, the pericentromeric regions of chromosomes 1, 3, and 14, and segments 6q15-21, 8q24, 9q34, 12p13, 17p13, and 19q13, were found to be involved in five or more structural rearrangements. Molecular analyses of these chromosome regions may yield genes important in the pathogenesis of osteosarcoma.