Enteric circular muscle dysfunction in the cystic fibrosis mouse small intestine

BACKGROUND Cystic fibrosis (CF) has multiple effects on the gastrointestinal system, including altered motility. The Cftr knockout mouse model of CF has impaired small intestinal transit but the mechanism is unknown. METHODS Behaviour of circular smooth muscle was studied in an organ bath. Expression levels of prostaglandin (PG) degradative genes were measured by quantitative RT-PCR, and PGE(2) levels were measured by enzyme immunoassay. KEY RESULTS Cystic fibrosis circular muscle activity was erratic and had variable frequency of contractions, as compared to WT. The CF tissue was non-responsive to cholinergic stimulation or direct KCl depolarization. PGE(2) and PGF(2alpha) are significantly elevated in the CF mouse small intestine, and we hypothesized these contribute to impaired smooth muscle activity. After inhibition of PG synthesis, the CF circular muscle exhibited greater cholinergic responsiveness, which was reversed by exogenous PGE(2). PGF(2alpha) enhanced activity of CF tissue only after inhibition of PG synthesis. The enteric microbiota was implicated in PGE(2)-mediated dysmotility because broad spectrum antibiotic treated WT mice, which have slowed transit, exhibit impaired circular muscle activity. This was accompanied by decreased expression of PG degradative genes and increased intestinal PGE(2) levels. Furthermore, administration of oral laxative, which eradicates bacterial overgrowth and improves transit in CF mice, increased expression of PG degradative genes, decreased PGE(2) levels, and improved CF muscle activity. CONCLUSIONS & INFERENCES These results suggest that the enteric microbiota modulates PGE(2) levels in a complex manner, which affects enteric smooth muscle activity and contributes to slower small intestinal transit in CF.

Growth, processing, and optical properties of epitaxial Er2O3 on silicon

Erbium-doped materials have been investigated for generating and amplifying light in low-power chip-scale optical networks on silicon, but several effects limit their performance in dense microphotonic applications. Stoichiometric ionic crystals are a potential alternative that achieve an Er(3+) density 100 x greater. We report the growth, processing, material characterization, and optical properties of single-crystal Er (2)O(3) epitaxially grown on silicon. A peak Er(3+) resonant absorption of 364 dB/cm at 1535 nm with minimal background loss places a high limit on potential gain. Using high-quality microdisk resonators, we conduct thorough C/L-band radiative efficiency and lifetime measurements and observe strong upconverted luminescence near 550 and 670 nm.

Modulation of dose intensity in aerodigestive tract cancers: strategies to reduce toxicity

Advances in diagnostic and therapeutic radiology and a better understanding of cell biology are being applied in practical ways to modulate treatment morbidity. Conformal radiotherapy targets the cancer precisely and can be combined with new systemically administered radiosensitizers. The successes of conventional chemoradiation programs support continued study of newer ways to deliver systemic radiosensitizing chemotherapy. However, chemoradiation creates a narrower therapeutic window compared to irradiation alone and increased treatment intensity, even with conformal chemoradiation techniques, can potentially result in frequent complications, detrimental treatment delays, and decreased quality of life. Treatment schedules employing a "best tolerated time" modelfor systemic administration of radiosensitizing chemotherapy, based on the concept of chronotolerance, offer attractive ways to address the challenging problem of normal tissue toxicity associated with conformal chemoradiation. This approach may be beneficial in the elderly and those medically unfit to tolerate traditional dose-intense combined-modality schedules. Further evaluation of this concept is warranted, based on existing data.

Hepatocellular carcinoma and chemoembolization

BACKGROUND

Chemoembolization is often used in the treatment of hepatocellular carcinoma; however, there are limited data on its efficacy in an Australian setting.

AIMS

To review retrospectively the experience of 21 patients with hepatocellular carcinoma who collectively had 36 chemoembolizations performed between October 1995 and February 1999 in a teaching hospital and liver transplant centre in Victoria.

METHODS

Selective catheterization of the right or left hepatic arteries was performed. A mixture of cisplatin 50 mg, epirubicin 50 mg, mitomycin C 10 mg, Lipiodol and gelfoam was injected. Computed tomography (CT) scans were performed at baseline and at 1-3 months after chemoembolization. Outcome measures included response rates, toxicity, progression-free and overall survival.

RESULTS

CT response rates: partial response 19% (n = 7), median duration 11 months (range 2+ to 37+); minor response 17% (n = 6), median duration 7 months (1+ to 12+); stable disease 42% (n = 15), median duration 3 months (1+ to 15 months); and progressive disease 22% (n = 8). Major toxicities included one case each of acute renal failure, contrast encephalopathy, gastric ulceration and hepatorenal failure. Median progression-free survival was 3 months (range 0-37+). Median overall survival was 15 months (range 6-50+).

CONCLUSION

Chemoembolization has a role in the palliative treatment of hepatocellular carcinoma. Our response rates and toxicity data are consistent with those in the published literature. However, new treatments are needed and prevention of disease by reduction in the prevalence of chronic hepatitis B and C will be required to significantly reduce mortality from this tumour.

Causes of recurrence after laparoscopic hernioplasty. A multicenter study

BACKGROUND

To determine if there are common factors beyond the learning curve that lead to recurrence after laparoscopic hernioplasty, we analyzed failures seen in seven centers specializing in laparoscopic hernia repair.

METHOD

We performed a retrospective review of patients who had a laparoscopic hernioplasty (Tapp or Tep) between 1990 and 1996 at centers specializing in laparoscopic repairs (>500 repairs at each center).

RESULTS

In all, 7661 patients had 10,053 hernias repaired by the transabdominal preperitoneal or the totally extraperitoneal approach; they were followed for 1 month to 6 years. In patients followed for >/=6 months with a median follow-up of 36 months, 35 repairs failed (0.4%), and all but one of these patients underwent a remedial operation. Twenty-nine had a laparoscopic repair, four had a combined laparoscopic and anterior repair, and one had an anterior repair alone. The cause of failure was determined in all 34 patients. The mechanism of recurrence was inadequate lateral fixation of the mesh in 11 cases, inadequate lateral fixation compounded by too small a mesh in three cases, missed lipoma of the cord in four cases, inadequate fixation of the mesh medially to Cooper's ligament in eight cases (seven of which were associated with too small a mesh), a missed hernia in four cases, and a hernia through a keyhole in the mesh in five cases. As surgeons gained experience, the incidence of recurrence due to missed hernias or too small a mesh decreased.

CONCLUSIONS

This large multicenter study demonstrated that the incidence of recurrence after laparoscopic hernioplasty performed by experienced surgeons was extremely low and that some causes could be corrected by experience, whereas others will require changes in technique or equipment.

Budd-Chiari syndrome: intractable ascites managed by a trans-hepatic portacaval shunt

Transjugular intrahepatic portosystemic shunts (TIPS) have recently been used to manage the portal hypertensive complications of the Budd-Chiari syndrome. We report this application of TIPS (to our knowledge the first such application in Australia) in a young man with an excellent result and no major complications. This treatment offers an alternative to portacaval shunt surgery and has the advantage of bypassing a stenosed or compressed inferior vena cava. Additionally, the procedure does not complicate liver transplantation surgery if this is indicated at a later date.

Identification of hepatic cirrhosis by duplex doppler ultrasound value of the hepatic artery resistive index

Pulsed Doppler Ultrasound was used to analyze hepatic artery wave forms near the porta hepatis. The Resistive Index (RI) = [peak systolic frequency shift (A)--minimum diastolic frequency shift (B)]/[peak systolic frequency shift (A)] has been calculated from this information. Two populations have been compared; 30 fit hospital staff members, 23 male, 7 female, age mean 37 years and range 19 to 73 years, and 33 cirrhotic potential liver transplant recipients, 16 male, 17 female, age mean 48 years and range 11 to 78 years. The RI was successfully obtained in 94% of the potential transplant patients. There is a significant difference between the RI of the controls (mean = 0.72, SE = 0.2, n = 27) and the cirrhotics (mean = 0.82, SE = 0.2, n = 31), P less than 0.0001. Using a cut off of greater than 0.77 this index has a sensitivity, specificity and overall accuracy of 68%, 70% and 69% respectively.

Lack of effect of omeprazole, a potent inhibitor of gastric (H+ + K+) ATPase, on hepatic lysosomal integrity and enzyme activity

The substituted benzimidazole, omeprazole, is a potent inhibitor of the ATP-dependent proton pump of the parietal cell. Since there is accumulating evidence that hepatic lysosomes also possess an ATP-dependent proton pump system to maintain internal acidification, and since antibodies to the putative lysosomal proton pump protein are immunologically similar to the parietal cell (H+ + K+) ATPase, we studied the effects in rats of six days of omeprazole treatment on hepatic lysosomal function. Omeprazole, 5 mg kg-1, a dose five times the ED50 for gastric acid secretion inhibition in rats, did not alter the activity of three representative lysosomal enzymes in liver (acid phosphatase, beta-galactosidase and N-acetyl-beta-glucosaminidase) nor did it alter lysosomal enzyme latency, a measure of the integrity of the lysosomal membrane. Furthermore, bile flow and the secretion of lysosomal enzymes into bile were also unaffected by omeprazole. These data indicate that in rats short-term treatment with omeprazole, in doses that markedly inhibit gastric acid secretion, has no major biological effect on liver lysosomal integrity and lysosomal enzyme activity.

High mean platelet volume after myocardial infarction: is it due to consumption of small platelets?

Seventy nine men surviving after sustaining a myocardial infarction in 1982, and who had at that time had raised mean platelet volumes compared with controls, were followed up after 18 months. The shape of each man's platelet distribution curve was calculated from the mean platelet volume, platelet count, and platelet distribution width. The calculated curves were in close agreement with the curves plotted by the Coulter counter from the raw data. These curves did not differ significantly from those of a current control group, but the curves plotted from the variables measured at the time of myocardial infarction in 1982 showed a deficit of platelets in the volume range 5-12 fl amounting at maximum to 30% (p less than 0.0001); there were no significant differences above 12 fl. The deficit of small platelets became more appreciable during initial admission, was less at one month's follow up, and had disappeared at one year. The deficit of small platelets is probably an effect rather than a cause of infarction.

Chlorpromazine effects on behavior under escape and fixed-time delivery of shock

Chlorpromazine has typically been found to reduce responding maintained by negative reinforcement. In squirrel monkeys, however, it has been shown to increase manipulative responses that occur just prior to shock presented under a fixed-time schedule. The present study compared chlorpromazine effects on behavior of rats under a fixed-time schedule of shock delivery and a schedule involving escape from shock. In all conditions, shock was delivered to the tail of rats held in partial restraint, and the response measured was displacement of a panel positioned directly in front of the rat's nose. The escape and fixed-time schedules generated similar temporal patterns and rates of responding under both schedules, and had no differential effect on the temporal distribution of responses within the shock interval.

Primary malignant fibrous histiocytoma of the intestine: intussusception of a rare neoplasm

Malignant fibrous histiocytoma, a tumor of mesenchymal tissue, is being reported with increased frequency. However, no cases of primary tumors involving the gastrointestinal tract have yet been described. This report documents a case in which the patient clinically manifested a colonic obstruction associated with intussusception. Following radical resection of the mass, close re-evaluation after one year has shown no evidence of tumor recurrence.

The recognition and treatment of the irritable bowel syndrome

The irritable bowel syndrome (IBS) is characterized by abdominal pain and/or altered bowel habit in the absence of detectable organic bowel disease. By convention, people with simple constipation are not usually included in this group of patients. IBS is a symptom-complex with many synonyms such as irritable colon, functional bowel disorder, nervous diarrhoea or spastic colon.