Effects of two methods of reconstruction of digestive tract after total gastrectomy on gastrointestinal motility in rats

Comparative evaluation of two reconstructive methods following laparoscopic assisted subtotal gastrectomy in dogs

BACKGROUND

Laparoscopic gastrectomy is a new and technically challenging surgical procedure with potential benefit. The objective of this study was to investigate clinical and para-clinical consequences following Roux-en-Y and Jejunal Loop interposition reconstructive techniques for subtotal gastrectomy using laparoscopic assisted surgery.

RESULTS

Following resection of the stomach attachments through a laparoscopic approach, stomach was removed and reconstruction was performed with either standard Roux-en-Y (n = 5) or Jejunal Loop interposition (n = 5) methods. Weight changes were monitored on a daily basis and blood samples were collected on Days 0, 7 and 21 post surgery. A fecal sample was collected on Day 28 after surgery to evaluate fat content. One month post surgery, positive contrast radiography was conducted at 5, 10, 20, 40, 60 and 90 minutes after oral administration of barium sulfate, to evaluate the postoperative complications. There was a gradual decline in body weight in both experimental groups after surgery (P < 0.05). There was no difference in blood parameters at any time after surgery between the two methods (P > 0.05). Fecal fat content increased in the Roux-en-Y compared to the Jejunal loop interposition technique (P < 0.05). No major complications were found in radiographs and gastric emptying time was similar between the two groups (P > 0.05).

CONCLUSION

Roux-en-Y and Jejunal loop interposition techniques might be considered as suitable approaches for reconstructing gastro-intestinal tract following gastrectomy in dogs. The results of this study warrant further investigation with a larger number of animals.

Linaclotide, through activation of guanylate cyclase C, acts locally in the gastrointestinal tract to elicit enhanced intestinal secretion and transit

Linaclotide is a first-in-class, orally administered 14-amino acid peptide that is in development for the treatment of irritable bowel syndrome with constipation and chronic constipation. We have characterized the solution structure of linaclotide, the in vitro binding and agonist activity to guanylate cyclase C receptors, the stability of linaclotide under conditions mimicking the gastric environment, oral bioavailability, and the pharmacodynamic effects in rat models of gastrointestinal transit and intestinal secretion. Nuclear magnetic resonance spectroscopy analysis determined that the molecular structure of linaclotide is stabilized by three intramolecular disulfide bridges. Linaclotide exhibited high affinity and pH-independent binding (K(i): 1.23-1.64 nM) to guanylate cyclase C receptors on human colon carcinoma T84 cells and concomitantly, linaclotide binding resulted in a significant, concentration-dependent accumulation of intracellular cyclic guanosine-3', 5'-monophosphate (cGMP) (EC₅₀:99 nM). Linaclotide was stable after 3 h incubation in simulated gastric fluid (pH 1) and similarly, was completely resistant to hydrolysis by pepsin. Pharmacokinetic analysis of linaclotide showed very low oral bioavailability (0.1%). Orally administered linaclotide elicited a significant, dose-dependent increase in gastrointestinal transit rates in rats at doses of ≥5 μg/kg. Exposure of surgically ligated small intestinal loops to linaclotide induced a significant increase in fluid secretion, accompanied by a significant increase in intraluminal cGMP levels. These results suggest that the guanylate cyclase C agonist linaclotide elicits potent pharmacological responses locally in the gastrointestinal tract, and that orally administered guanylate cyclase C agonists may be capable of improving bowel habits in patients suffering from irritable bowel syndrome with constipation and chronic constipation.

The effects of Roux-en-Y limb length on gastric emptying and enterogastric reflux in rats

PURPOSE

To assess the effects of Roux-en-Y jejunal limb length on gastric emptying and enterogastric reflux.

METHODS

Seventy male Wistar rats were submitted to antrectomy with Roux-en-Y reconstruction and then were divided into two groups of 35 animals. Group A, short limb (7.5 cm) and Group B, standard limb (15 cm). Group A and B were subdivided into five subgroups each in order to study enterogastric reflux at 30 and 60 minutes and to evaluate gastric emptying at 5, 10 and 15 minutes. In order to measure gastric emptying and enterogastric reflux, radiotracers 99m Tc-Phytate and 99m Tc-DISIDA were respectively used.

RESULTS

For gastric emptying, the radiotracer concentration was lower in Group A than in Group B after five minutes. The enterogastric reflux was present, but there were no significant differences between enterogastric reflux indexes concerning both A and B Groups.

CONCLUSION

A standard Roux limb, besides being unable to protect the stomach from the enterogastric reflux, may become a functional barrier for gastric emptying.

Comparative study on three types of alimentary reconstruction after total gastrectomy

BACKGROUND

More than 70 alimentary reconstruction procedures after total gastrectomy have been proposed to reduce the postoperative syndromes such as dumping syndrome, reflux esophagitis, and malnutrition. However, the optimal alimentary reconstruction method is still a matter of debate. The aim of the current study was to investigate the rationality of different alimentary tract reconstruction methods after total gastrectomy for gastric malignancy.

METHODS

Three types of digestive reconstruction methods were performed after total gastrectomy in 285 cases of gastric malignancy from May 1996 to December 2006, including Orr-type Roux-en-Y reconstruction (Orr-type), P-type Roux-en-Y reconstruction (P-type), and Moynihan-type reconstruction (Moynihan-type) methods. The operative time, early postoperative complications and mortality, food intake, alimentary symptoms, Visick scores, nutritional status at 1 and 3years after surgery, and cumulative survival at 1, 3, and 5years were comparatively analyzed.

RESULTS

There were no significant differences among the three methods in early postoperative complications and mortality, postoperative food intake and nutritional status (hemoglobin, total proteins and albumin), and incidence of diarrhea and dumping syndrome at 1 and 3years (p > 0.05). The overall 1-, 3-, and 5-year cumulative survival rate were 75.30%, 39.86%, and 21.48%, respectively, without significant differences among the three groups (p > 0.05). However, the average operative time used in the Orr-type reconstruction method (2.9 +/- 0.1h) was comparatively shorter than that used in the P-type (3.4 +/- 0.2h) and the Moynihan-type (3.2 +/- 0.1h). The incidences of reflux esophagitis after the gastric reconstruction with the Moynihan-type method at 1 and 3years (72% and 65%) were significantly higher than that with the Orr-type (3% and 0%) and P-type (5% and 0%; p < 0.01). Constituent ratio of Visick scores I-II of the Moynihan-type method at 1 and 3years (54% and 73%) were smaller than that of the Orr-type (94% and 96%) and the P-type (93% and 96%) methods (p < 0.01).

CONCLUSION

Orr-type Roux-en-Y reconstruction method can avoid reflux esophagitis, and the procedure is simpler than the other two methods. Therefore, Orr-type Roux-en-Y reconstruction can be recommended as an adoptable method of digestive reconstruction after total gastrectomy for gastric cancer.

Myoelectric activity and motility of the Roux limb after cut or uncut Roux-en-Y gastrojejunostomy

AIM: To explore the mechanisms of uncut Roux-en-Y gastrojejunostomy, which is used to decrease the occurrence of Roux stasis syndrome.

METHODS: The changes of myoelectric activity, mechanic motility and interstitial cells of Cajal (ICC) of the Roux limb after cut or uncut Roux-en-Y gastrojejunostomy were observed.

RESULTS: When compared with the cut group, the amplitude (1.15 ± 0.15 mV vs 0.48 ± 0.06 mV, P < 0.05) and frequency (14.4 ± 1.9 cpm vs 9.5 ± 1.1 cpm, P < 0.01) of slow waves and the incidence (98.2% ± 10.4% vs 56.6% ± 6.4%, P < 0.05) and amplitude (0.58 ± 0.08 mV vs 0.23 ± 0.06 mV, P < 0.01) of spike potential of the Roux limb in the uncut group were significantly higher. The migrating myoelectric complexes (MMC) phase III duration in the uncut group was significantly prolonged (6.5 ± 1.1 min vs 4.4 ± 0.8 min, P < 0.05), while the MMC cycle obviously shortened (42.5 ± 6.8 vs 55.3 ± 8.2 min, P < 0.05). Both gastric emptying rate (65.5% ± 7.9% vs 49.3% ± 6.8%, P < 0.01) and intestinal impelling ratio (53.4% ± 7.4% vs 32.2% ± 5.4%, P < 0.01) in the uncut group were significantly increased. The contractile force index of the isolated jejunal segment in the uncut group was significantly higher (36.8 ± 5.1 vs 15.3 ± 2.2, P < 0.01), and the expression of c-kit mRNA was significantly increased in the uncut group (0.82 ± 0.11 vs 0.35 ± 0.06, P < 0.01).

CONCLUSION: Uncut Roux-en-Y gastrojejunostomy may lessen the effects of operation on myoelectric activity such as slow waves, spike potential, and MMC, decrease the impairment of gastrointestinal motility, and remarkably increase the expression of c-kit mRNA.

Changes in GI hormones and their effect on gastric emptying and transit times after Roux-en-Y gastric bypass in rat model

BACKGROUND

We determined whether Roux-en-Y gastric bypass (RYGB)-induced protracted weight loss is associated with an increase in anorectic peptide YY (PYY) and decreased gastrointestinal (GI) motility.

METHODS

RYGB and control sham-operated GI intact obese (SO Obese) and sham-operated GI intact pair-fed (PF) rats were studied. Postoperatively, body weight (BW) and food intake were measured for 90 days. Rats were killed to measure PYY, ghrelin, cholecystokinin (CCK), and glucagonlike peptide-1 (GLP-1). Ninety-day food intake trends were examined by quadratic trend analysis. On the basis of a 28-day weight loss rate, PYY also was measured at 14 and 28 days. Peak 28-day PYY results corresponded with peak BW loss rate; thus, gastric emptying (GE) and intestinal transit time were measured. Data were analyzed by analysis of variance and Tukey's pairwise multiple comparison.

RESULTS

At 90 days, BW in SO Obese versus PF versus RYGB rats was 801 +/- 15 g versus 661 +/- 24 g versus 538 +/- 32 g respectively (P < .05). Concentrations of plasma PYY were increased, while plasma ghrelin was decreased in RYGB versus SO Obese and PF (P < .05). CCK and GLP-1 were unchanged. In RYGB versus controls, PYY was increased at 14 and 28 days but was most elevated at 28 days. In RYGB versus controls, GE was delayed (P < .05) and intestinal transit time was longer (P < .05).

CONCLUSIONS

After RYGB, an increase in PYY and a decrease in ghrelin occurred, probably explaining the decrease in food intake, the slower GE and transit time, which contributed to weight loss. Longitudinal studies can be performed with the use of our RYGB model, providing insight into weight loss mechanisms by generating long-term follow-up data currently not available in human studies.