Association between plasma ghrelin and motilin levels during MMC cycle in conscious dogs

BACKGROUND

Migrating motor complex (MMC) is well characterized by the appearance of gastrointestinal contractions in the interdigestive state. Gastric phase III contractions of MMC are regulated by motilin, but not ghrelin, in dogs. Ghrelin regulates feeding activity in dogs and rodents. It remains unclear how motilin and ghrelin interact during the MMC cycle in dogs.

METHODS

Four strain gauge transducers were implanted on stomach and intestine in 6 female dogs. To investigate the correlation between ghrelin and motilin, plasma motilin and acyl ghrelin (active type) levels were measured by radioimmunoassay (RIA) during MMC cycle.

RESULTS

The peak of plasma motilin levels was always observed at the period of gastric phase III contractions. The peak of ghrelin levels were followed 20-25 min after the peak of plasma motilin levels in 13 cases of 18 observations (72.2%). These were frequently observed at the early stage of gastric phase I contractions. In 3 of 16 observations (18.8%), the ghrelin peak was not associated with the motilin peaks. Immediately after the feeding, the interdigestive GI motor pattern was changed to the postprandial pattern. No significant increases of the plasma motilin levels and ghrelin levels were observed after the feeding.

CONCLUSION

This is the first demonstration showing the correlation between ghrelin and motilin levels during gastric MMC cycle in conscious dogs. As it is rather difficult to evaluate the hunger score in dogs, it remains unclear whether increased ghrelin levels after finishing gastric phase III contractions may mediate hunger sensation in dogs.

Effects of autonomic nerve stimulation on colorectal motility in rats

BACKGROUND

Several disease processes of the colon and rectum, including constipation and incontinence, have been associated with abnormalities of the autonomic nervous system. However, the autonomic innervation to the colon and rectum are not fully understood. The aims of this study were to investigate the effect of stimulation of vagus nerves, pelvic nerves (PN) and hypogastric nerves (HGN) on colorectal motility in rats.

METHODS

Four strain gauge transducers were implanted on the proximal colon, mid colon, distal colon and rectum to record circular muscle contractions in rats. Electrical stimulation was administered to the efferent distal ends of the cervical vagus nerve, PN and HGN. Motility index (MI) was evaluated before and during stimulation.

KEY RESULTS

Electrical stimulation (5-20 Hz) of the cervical vagus elicited significant contractions in the mid colon and distal colon, whereas less pronounced contractions were observed in the proximal colon. Pelvic nerves stimulation elicited significant contractions in the rectum as well as the mid colon and distal colon. Atropine treatment almost completely abolished the contractions induced by vagus nerve and PN stimulation. Hypogastric nerves stimulation caused relaxations in the rectum, mid colon and distal colon. The relaxations in response to HGN stimulation were abolished by propranolol.

CONCLUSIONS & INFERENCES

Vagal innervation extends to the distal colon, while the PN has projections in the distribution of the rectum through the mid colon. This suggests a pattern of dual parasympathetic innervation in the left colon. Parasympathetic fibers regulate colorectal contractions via muscarinic receptors. The HGN mainly regulates colorectal relaxations via beta-adrenoceptors.

The role of 5-HT3 and 5-HT4 receptors in the adaptive mechanism of colonic transit following the parasympathetic denervation in rats

BACKGROUND

Clinical studies show that disturbed colonic motility induced by extrinsic nerves damage is restored over time. We studied whether 5-HT3 and 5HT4 receptors are involved in mediating the adaptive mechanisms following parasympathetic denervation.

METHODS

Parasympathetic denervation of the entire colon was achieved by bilateral pelvic nerve transection and truncal vagotomy in rats. Colonic transit was measured by calculating the geometric center (GC) of 51Cr distribution. Expression of 5-HT3 and 5HT4 receptor mRNA was determined by real time RT-PCR.

RESULTS

Parasympathetic denervation caused a significant delay in colonic transit (GC=4.36) at postoperative day (POD) 1, compared with sham operation (GC=6.31). Delayed transit was gradually restored by POD 7 (GC=5.99) after the denervation. Restored colonic transit was antagonized by the administration of 5-HT3 and 5HT4 receptors antagonists at POD 7. 5-HT3 and 5HT4 receptors mRNA expression were significantly increased in the mucosal/submucosal layer at POD 3 or POD 7, whereas no significant difference was observed in the longitudinal muscle layers adherent with the myenteric plexus (LMMP).

CONCLUSIONS

It is suggested that up-regulation of 5-HT3 and 5-HT4 receptors expression in the mucosal/submucosal layer is involved to restore the delayed transit after the parasympathetic denervation in rats.

The role of 5-HT3 and 5-HT4 receptors in the adaptive mechanism of colonic transit following the parasympathetic denervation in rats

BACKGROUND

Clinical studies show that disturbed colonic motility induced by extrinsic nerves damage is restored over time. We studied whether 5-HT3 and 5HT4 receptors are involved in mediating the adaptive mechanisms following parasympathetic denervation.

METHODS

Parasympathetic denervation of the entire colon was achieved by bilateral pelvic nerve transection and truncal vagotomy in rats. Colonic transit was measured by calculating the geometric center (GC) of 51Cr distribution. Expression of 5-HT3 and 5HT4 receptor mRNA was determined by real time RT-PCR.

RESULTS

Parasympathetic denervation caused a significant delay in colonic transit (GC=4.36) at postoperative day (POD) 1, compared with sham operation (GC=6.31). Delayed transit was gradually restored by POD 7 (GC=5.99) after the denervation. Restored colonic transit was antagonized by the administration of 5-HT3 and 5HT4 receptors antagonists at POD 7. 5-HT3 and 5HT4 receptors mRNA expression were significantly increased in the mucosal/submucosal layer at POD 3 or POD 7, whereas no significant difference was observed in the longitudinal muscle layers adherent with the myenteric plexus (LMMP).

CONCLUSIONS

It is suggested that up-regulation of 5-HT3 and 5-HT4 receptors expression in the mucosal/submucosal layer is involved to restore the delayed transit after the parasympathetic denervation in rats.

Expanding CEP290 mutational spectrum in ciliopathies

Ciliopathies are an expanding group of rare conditions characterized by multiorgan involvement, that are caused by mutations in genes encoding for proteins of the primary cilium or its apparatus. Among these genes, CEP290 bears an intriguing allelic spectrum, being commonly mutated in Joubert syndrome and related disorders (JSRD), Meckel syndrome (MKS), Senior-Loken syndrome and isolated Leber congenital amaurosis (LCA). Although these conditions are recessively inherited, in a subset of patients only one CEP290 mutation could be detected. To assess whether genomic rearrangements involving the CEP290 gene could represent a possible mutational mechanism in these cases, exon dosage analysis on genomic DNA was performed in two groups of CEP290 heterozygous patients, including five JSRD/MKS cases and four LCA, respectively. In one JSRD patient, we identified a large heterozygous deletion encompassing CEP290 C-terminus that resulted in marked reduction of mRNA expression. No copy number alterations were identified in the remaining probands. The present work expands the CEP290 genotypic spectrum to include multiexon deletions. Although this mechanism does not appear to be frequent, screening for genomic rearrangements should be considered in patients in whom a single CEP290 mutated allele was identified.

Central oxytocin is involved in restoring impaired gastric motility following chronic repeated stress in mice

Accumulation of continuous life stress (chronic stress) often causes gastric symptoms. The development of gastric symptoms may depend on how humans adapt to the stressful events in their daily lives. Although acute stress delays gastric emptying and alters upper gastrointestinal motility in rodents, the effects of chronic stress on gastric motility and its adaptation mechanism remains unclear. Central oxytocin has been shown to have antistress effects. We studied whether central oxytocin is involved in mediating the adaptation mechanism following chronic repeated stress. Mice were loaded with acute and chronic stress (repeated stress for five consecutive days), and solid gastric emptying and postprandial gastric motility were compared between acute and chronic repeated stress. Expression of oxytocin and CRF mRNA in the hypothalamus was studied following acute and chronic repeated stress. Delayed gastric emptying during acute stress (43.1 +/- 7.8%; n = 6, P < 0.05) was completely restored to normal levels (72.1 +/- 2.4%; n = 6) following chronic repeated stress. Impaired gastric motility induced by acute stress was also restored following chronic repeated stress. Intracerebroventricular injection of oxytocin (0.1 and 0.5 microg) restored the impaired gastric emptying and motility induced by acute stress. The restored gastric emptying and motility following chronic repeated stress were antagonized by intracerebroventricular injection of oxytocin antagonists. Oxytocin mRNA expression in the supraoptic nucleus (SON) and paraventricular nucleus (PVN) of the hypothalamus was significantly increased following chronic repeated stress. In contrast, increased CRF mRNA expression in the SON and PVN in response to acute stress was significantly reduced following chronic repeated stress. Our study suggests the novel finding that the upregulation of central oxytocin expression is involved in mediating the adaptation mechanism following chronic repeated stress in mice.

Evidence of thromboembolism prophylaxis in bariatric surgery-results of a quality assurance trial in bariatric surgery in Germany from 2005 to 2007 and review of the literature

BACKGROUND

Since January 1st, 2005, the current situation for bariatric surgery has been examined by means of a voluntary quality assurance study in Germany with a multicenter design in which 38 hospitals and surgical departments participated. The data are registered in cooperation with the Institute of Quality Assurance in Surgery at the Otto-von-Guericke University of Magdeburg (Germany).

METHODS

Data describing peri-interventional characteristics were prospectively documented in an internet online data registry. All primary bariatric procedures performed since January 1st, 2005, were registered. In addition, reoperations in patients who had previously undergone primary surgical intervention were included. As a representative excerpt from the overall prospective multicenter observational study on obesity surgery, data on the type, regimen, and time course of deep venous thrombosis (DVT) prophylaxis were documented. From the number and spectrum of complications, the incidences of clinically manifest DVT or pulmonary embolism (PE) were derived during the in-hospital course and follow-up in conjunction with the type of surgical procedure and body mass index (BMI).

RESULTS

Overall, 3,122 bariatric procedures were performed at 38 German hospitals between January 2005 and December 2007. These procedures were subdivided into 2,869 primary operations and 253 revisions (sex ratio, male to female = 25.6:74.4%). The average BMI of all patients was 48.5 kg/m(2) in 2005, 48.4 kg/m(2) in 2006, and 48.0 kg/m(2) in 2007. In 2005 and 2006, gastric banding (GB) was the most commonly performed operation, followed by Roux-en-Y gastric bypass (RYGBP). In 2007, RYGBP was carried out in 42.1% of all bariatric procedures. Interestingly, the incidence of deep venous thrombosis (DVT) was only 0.06%, whereas PE occurred in 0.06% of patients only after hospital discharge. The DVT prophylaxis protocol used has been changed for the last 2 years: the majority of patients with a BMI above 50 kg/m(2) received low-molecular-weight heparin twice a day.

CONCLUSION

In Germany, a trend from GB to sleeve gastrectomy (SG) and malabsorptive approach has been evaluated. This trend is associated with differences of the DVT prophylaxis regimen in the profile of bariatric surgical patients depending on BMI and the type of bariatric procedure. Despite the low incidence of DVT and pulmonary embolism (PE) detected, there is a lack of evidence on a reasonable regimen for sufficient DVT prophylaxis in bariatric surgery; instead, there are only recommendations from the guidelines and statements of a specific medical society. Therefore, prospective studies are necessary to determine the optimal DVT prophylaxis for bariatric surgical patients as well as obese patients undergoing surgery.

Effects of repeated restraint stress on gastric motility in rats

In our daily life, individuals encounter with various types of stress. Accumulation of daily life stress (chronic stress) often causes gastrointestinal symptoms and functional gastrointestinal diseases. Although some can adapt toward chronic stress, the adaptation mechanism against chronic stress remains unknown. Although acute stress delays gastric emptying and alters upper gastrointestinal motility, effects of chronic stress on gastric motility still remain unclear. We investigated the effects of acute (single stress) and chronic (repeated stress for 5 consecutive days) stress on solid gastric emptying and interdigestive gastroduodenal contractions in rats. It is well established that acute restraint stress inhibits solid gastric emptying via central corticotropin-releasing factor (CRF). To investigate whether the sensitivity to CRF is altered following chronic stress, CRF was administered intracisternally. Ghrelin is involved in regulating gastric emptying and upper gastrointestinal motility in rodents. The changes in plasma active ghrelin levels and mRNA expression in the stomach were studied following chronic stress. To evaluate the effects of chronic stress on the hypothalamus-pituitary-adrenal (HPA) axis, plasma corticosterone levels were also measured. Delayed gastric emptying observed in acute stress was completely restored following chronic stress. Acute stress abolished gastric phase III-like contractions, without affecting duodenal phase III-like contractions in the interdigestive state. Impaired gastric phase III-like contractions were also restored following chronic stress. Plasma ghrelin levels and ghrelin mRNA expression were increased significantly after chronic stress. Intracisternal injection of CRF delayed gastric emptying and impaired gastric motility in rats who received chronic stress. Plasma corticosterone concentrations were no more elevated following chronic stress. The restored gastric emptying following chronic stress was antagonized by the administration of ghrelin receptor antagonists. The adaptation mechanism may involve upregulation of ghrelin expression and attenuation of the HPA axis. In contrast, the sensitivity to central CRF remained unaltered following chronic stress in rats.

Ghrelin regulates gastric phase III-like contractions in freely moving conscious mice

In humans and dogs, motilin regulates phase III contractions of migrating motor complex (MMC) in the interdigestive state, while ghrelin regulates MMC in rats. It still remains unclear whether ghrelin regulates phase III contractions of the mouse stomach. A miniature strain gauge transducer was sutured on the antrum to detect circular muscle contractions and gastric contractions of the interdigestive state were evaluated. Effects of ghrelin, a ghrelin receptor antagonist, and atropine on spontaneous gastric contractions were studied in freely moving conscious mice. Similar to the rat stomach, phase III-like contractions were observed in the interdigestive state, which disappeared immediately after the feeding. Ghrelin augmented spontaneous phase III-like contractions, while growth-hormone secretagogue receptor antagonists and atropine abolished the occurrence of spontaneous phase III-like contractions. The spontaneous phase III-like contractions were no more observed in vagotomized mice. These results suggest that ghrelin regulates phase III-like contractions in mice stomach via its own receptors. Ghrelin-induced gastric phase III-like contractions are mediated via vagal cholinergic pathways in mice. Our recording system of mice gastric motility may be useful to study the functional changes in gene knockout mice, in the future.

Effects of ghrelin on interdigestive contractions of the rat gastrointestinal tract

Ghrelin causes interdigestive contractions of the stomach in rats. However, it remains unknown whether ghrelin causes interdigestive contractions in the small intestine. Four strain gauge transducers were implanted on the antrum, duodenum, proximal and distal jejunum. After an overnight fast, gastrointestinal (GI) contractions were recorded in freely moving conscious rats. Spontaneous phase III-like contractions were observed at every 13-16 min in rat GI tract. The fasted motor patterns were replaced by the fed motor pattern immediately after food intake. Two minutes after finishing the spontaneous phase III-like contractions in the antrum, acyl ghrelin (0.8, 2.4 and 8.0 μg/kg per min) was continuously infused for 30 min. Three-five minutes after the starting ghrelin infusion, augmented phase III-like contractions were observed at the antrum, duodenum, and jejunum. Ghrelin infusion (0.8, 2.4 and 8.0 μg/kg per min) significantly increased motility index of phase III-like contractions at the antrum and jejunum in a dose dependent manner, compared to that of saline injection. Thus, it is likely that exogenously administered ghrelin causes phase III-like contraction at the antrum, which migrates to the duodenum and jejunum. The possible role of 5-HT, in addition to ghrelin, in mediating intestinal migrating motor complex (MMC), is discussed.

A nationwide survey on bariatric surgery in Germany--results 2005-2007

BACKGROUND

Most studies on bariatric surgery outcomes are performed as clinical trials or reflect the clinical experience in single centers. The status of bariatric surgery in Germany has been examined since January 1st, 2005 with the cooperation of clinics and hospitals at the Institute of Quality Assurance in Surgery at the Otto-von-Guericke University of Magdeburg (Germany).

METHODS

In this prospective multicenter observational study, the data obtained for all primary bariatric procedures, including all repeated operations, performed on consecutive patients with morbid obesity at participating hospitals from 2005 to 2007 were prospectively collected using an Internet online data registry. In particular, perioperative characteristics, such as the spectrum of diagnostic measurements, type of surgical procedures, and short- and long-term outcomes, were investigated.

RESULTS

During the study period, 629 surgical procedures were performed at 21 hospitals in 2005, 828 procedures at 32 hospitals in 2006, and 1,666 procedures at 35 hospitals in 2007. In 2005 and 2006, gastric banding was the most frequently performed operation, followed by the Roux-en-Y gastric bypass (RYGBP). In 2007, a RYGBP was carried out in 42.1% of all bariatric procedures. Among all patients, 74.4% were female. The mean body mass index (BMI) was 48.5 kg/m(2) in 2005, 48.4 kg/m(2) in 2006, and 48.0 kg/m(2) in 2007. Follow-up data after 12 months were available for 63.8% of the patients in 2005 and 2006; these data showed greater reduction of BMI after malabsorptive rather than restrictive bariatric procedures. The mortality was 0.1% (30 days) and 0.16% (overall).

CONCLUSION

As indicated by the worldwide trend, there is an ongoing change from restrictive bariatric procedures to malabsorptive procedures and sleeve gastrectomy. Although the BMIs of German patients undergoing bariatric surgery appear to be substantially higher than those of patients from most other countries, there were no differences in intraoperative and short-term complications or in overall outcomes during follow-up when compared with published studies.

[Quality assurance in bariatric surgery in Germany--results of the German multicentre trial 2005 and 2006]

BACKGROUND

Since January 1st 2005, the situation of bariatric surgery in Germany has been examined. The data are registered in cooperation with the Institute of Quality Assurance in Surgery at the Otto-von-Guericke-University Magdeburg.

METHODS

The data registration took place prospectively in an internet online data base. All primary bariatric procedures performed since January 1st 2005 were detected as well as re-operations in patients who had been operated before.

RESULTS

629 patients underwent bariatric surgery in 21 hospitals in 2005 and 828 patients were operated in 32 hospitals in 2006. The mostly performed operation was gastric banding with 46.8 %, followed by Roux-Y gastric bypass with 38.5 %. 74.4 % of the patients were female. The medium BMI of all patients was 48.5 kg/m2 in 2005 and 48.4 kg/m2 in 2006. Follow-up data were available for 71.2 % of the patients operated in 2005. These data show a higher reduction of BMI after malabsorptive than after restrictive bariatric procedures.

CONCLUSION

A trend from restrictive bariatric procedures to a malabsorptive approach could be observed. In Germany the BMI of patients undergoing bariatric surgery is higher than in most countries world-wide. No differences could be detected in intraoperative and short-term complications as well in the complication rate in the first year of follow-up in comparison with the literature.

Endogenous ghrelin and 5-HT regulate interdigestive gastrointestinal contractions in conscious rats

Endogenous ghrelin causes interdigestive contractions of the stomach in rats. In contrast, previous studies showed that 5-HT(3) and 5-HT(4) receptors were involved in regulating intestinal interdigestive contractions. We studied the possible role of endogenous ghrelin and 5-HT regulating interdigestive gastrointestinal (GI) contractions in rats. Four strain gauge transducers were implanted on the antrum, duodenum, and proximal and distal jejunum. After an overnight fast, GI contractions were recorded in freely moving conscious rats and ghrelin receptor antagonists [(d-lys3)GHRP6; 1 micromol/kg], 5-HT(3) antagonists (Ondansetron; 0.5 mg/kg) and 5-HT(4) antagonists (GR 125,487; 1 mg/kg) were administered (bolus iv). To evaluate the relationship between the luminal concentrations of 5-HT and phase III-like contractions of the duodenum, duodenal juice was collected via the intraduodenal catheter. 5-HT content of the duodenal juice was measured by HPLC. (d-lys3)GHRP6 significantly attenuated the occurrence and amplitude of phase III-like contractions of the antrum, but not the duodenum and jejunum. 5-HT(4) antagonists significantly reduced spontaneous phase III-like contractions of the jejunum, without affecting those of the antrum and duodenum. In contrast, 5-HT(3) antagonists did not affect phase III-like contractions in GI tract. Luminal concentration of 5-HT at the phase III-like contraction (36.0 +/- 13.3 ng/ml, n = 9) was significantly higher than that at the phase I-like contractions of the duodenum (4.9 +/- 1.6 ng/ml, n = 9, P < 0.05). It is suggested that released ghrelin from the gastric mucosa mediates gastric phase III-like contractions, whereas 5-HT released from enterochromaffin cells of the duodenal mucosa mediates intestinal phase III-like contractions via 5-HT(4) receptors.

Influence of saliva contamination on zirconia ceramic bonding

OBJECTIVES

The purpose of this study was to investigate the influence of saliva contamination and cleaning methods on adhesive bonding to dental zirconia ceramic with a phosphate-monomer-containing luting resin.

METHODS

After saliva immersion, airborne-particle abraded ceramic specimens were cleaned with water rinsing, with isopropanol, with phosphoric acid gel, or with additional airborne-particle abrasion. Airborne-particle abraded specimens without contamination were used as the control group. Chemical analysis of the ceramic surfaces of all groups was done using X-ray photoelectron spectroscopy (XPS). The influence of contamination and cleaning methods on ceramic bond durability was examined by tensile bond strength (TBS) testing after 3 days or 150 days water storage with 37,500 thermal cycles.

RESULTS

After saliva contamination XPS revealed an organic coating which was not removed completely with water rinsing, with isopropanol, or with phosphoric acid. Using TBS testing a strong influence of contamination and cleaning methods on resin bond strength and its durability was found.

SIGNIFICANCE

Saliva contamination significantly affected resin bonds to zirconia ceramic and its durability. Airborne-particle abrasion was the most effective cleaning method.