Management of malignant esophageal stricture with esophageal dilation and esophageal stents

Esophageal dilatation and endoprosthesis insertion are very useful techniques in the palliation of malignant esophageal strictures. Patients with tracheoesophageal fistula or tumors poorly responsive to dilation or other therapies will achieve benefit from esophageal stent placement. Although further studies are needed, it appears that the use of expansile metallic stents may be advantageous compared with the standard plastic stents.

Intrasphincteric injection of botulinum toxin for suspected sphincter of Oddi dysfunction

Botulinum toxin is a potent inhibitor of the release of acetylcholine from nerve endings. It has previously been shown that it can effectively reduce lower oesophageal sphincter pressures both in animals and humans with achalasia. This study examined the hypothesis that locally injected botulinum toxin could also reduce sphincter of Oddi pressure in patients with sphincter of Oddi dysfunction. Two patients with postcholecystectomy pain syndrome were diagnosed with sphincter of Oddi dysfunction (by biliary manometry in one patient and by hepatobiliary scanning criteria in the other). Botulinum toxin was injected into the sphincter of Oddi, by a sclerotherapy needle passed through a duodenoscope. In the first patient, intrasphincteric injection of botulinum toxin reduced sphincter pressure by about 50%, an effect that was sustained for at least four months. In the second patient, intrasphincteric injection caused about a 50% improvement in bile flow, with normalisation of scintigraphy. Neither patient showed any sustained improvement in pain despite these objective findings. Both patients eventually had endoscopic sphincterotomy, which also did not result in symptomatic improvement in either patient. No side effects were seen. Intrasphincteric botulinum toxin is a simple and effective means of lowering sphincter of Oddi pressure. This technique has potential for being useful clinically.

Gallbladder ejection fraction. Nondiagnostic for sphincter of Oddi dysfunction in patients with intact gallbladders

Thirty consecutive patients with intact gallbladders and biliary pain were evaluated to determine whether gallbladder ejection fraction could identify sphincter of Oddi dysfunction. The mean gallbladder ejection fraction was 45% in patients with abdominal pain and 72% in normal controls. Gallbladder ejection fractions were then correlated with endoscopically measured sphincter of Oddi pressures in patients with abdominal pain. The mean gallbladder ejection fraction was 41% in 7 patients with elevated sphincter pressures and 46% in 23 patients with normal pressures (P = NS). Thirty-six percent of patients with elevated pressures and 33% of patients with normal pressures had abnormal gallbladder ejection fractions. Gallbladder ejection fraction had a sensitivity of 33%, a specificity of 63%, and a positive predictive value of 25% for detection of elevated pressures. Regression analysis revealed a poor correlation between sphincter pressure and gallbladder ejection fraction (r2 = 0.02). These findings suggest that gallbladder ejection fraction cannot be used to diagnose sphincter of Oddi dysfunction in patients before they undergo cholecystectomy.

Effects of intrasphincteric botulinum toxin on the lower esophageal sphincter in piglets

BACKGROUND

The toxin of Clostridium botulinum (BoTx) inhibits the release of acetylcholine from nerve terminals and causes paralysis of skeletal muscle. The present study examined the hypothesis that BoTx may have a similar effect on gastrointestinal smooth muscle.

METHODS

Baseline lower esophageal sphincter (LES) pressures were obtained in five piglets, and normal saline was injected endoscopically into the LES. One week later, LES pressure was measured again, followed by injection of BoTx into the LES. After another week, LES pressure was measured again.

RESULTS

Compared with a baseline LES pressure of 8.2 +/- 1.5 mm Hg, LES pressure decreased to 3.2 +/- 1.0 mm Hg after BoTx injection, a reduction of about 60% (P < 0.01). By contrast, LES pressure did not change significantly after normal saline injection. The animals showed no evidence of toxicity. Data from other experiments showed that after injection with toxin, the LES responds normally to bethanechol and pentagastrin but displays a paradoxical response to edrophonium and cholecystokinin.

CONCLUSIONS

BoTx is a potent inhibitor of resting LES tone. Its relatively specific anticholinergic effect may help clarify the role of cholinergic and noncholinergic pathways in the regulation of gastrointestinal sphincters.

Prostaglandins E1 and E2 stimulate the proliferation of pulmonary artery smooth muscle cells

Prostaglandins E1 and E2 are thought to be inhibitors of the growth of systemic vascular smooth muscle cells (SMC). However, their effect on the proliferation of SMC from the pulmonary artery (PA) has not been described and was the subject of this investigation. Cultures of bovine PA SMC were exposed to PGE1 and PGE2 under various conditions and their growth was assessed. PGE1 and PGE2 did not inhibit the growth of PA SMC in 10% fetal calf serum (FCS), but instead caused a dose dependent (10 ng - 1 microgram/ml) increase in [3H]-thymidine incorporation when added to cultures containing 0.5% FCS; the highest doses resulted in 95% and 75% increases in [3H]-thymidine uptake at 24 hours with PGE1 and PGE2 respectively. This was accompanied by a modest increase in actual cell numbers (e.g., 20% with 1 microgram/ml PGE1). Furthermore, PGE1 could mimic insulin-like growth factor (IGF-1) by potentiating the stimulation of SMC growth by fibroblast growth factor, suggesting that PGE1 may act as a progression factor in the growth cycle of these cells. There was, however, no effect of PGE1 on the proliferation of bovine aortic SMC. We conclude that, contrary to most reported effects on systemic SMC, PGE1 and PGE2 do not inhibit the proliferation of PA SMC but rather stimulate it.

Hypoxia stimulates the release by bovine pulmonary artery endothelial cells of an inhibitor of pulmonary artery smooth muscle cell growth

The proliferation of smooth muscle cells (SMC) seen in hypoxic pulmonary hypertension is a poorly understood phenomenon but may involve endothelial cell (EC)-SMC interaction. Using bovine pulmonary artery cells, we examined the effect of O2 tension and the role of EC or media conditioned by EC (ECCM) on SMC proliferation. We found no difference in SMC proliferation under 3%, 10%, and 20% O2. EC, co-cultured with SMC in 3% O2, inhibited SMC proliferation consistently by about 40% (versus SMC exposed to hypoxia but not to EC). In normoxia, the degree of inhibition was dependent on EC:SMC ratio. In separate experiments, media from EC exposed to 3% or 20% O2 had a mitogenic activity of 24% and 42%, respectively (compared to 100% mitogenic activity with 5% FCS), on serum-deprived SMC. On the other hand, when SMC were stimulated to grow with FCS, an inhibitory activity (IA) from ECCM on SMC proliferation was observed and was significantly greater in hypoxic versus normoxic ECCM (40% versus 21%, respectively). Amicon concentration showed that the IA was contained in the less than 10 kD fraction of ECCM. Preliminary characterization of this IA indicates that it is unlike any of the known inhibitors of SMC growth, such as lactic acid, prostaglandin derivatives, or heparan sulfate. We conclude that hypoxia causes pulmonary artery EC to release a unique inhibitor of SMC growth.