ANP32A represses Wnt signaling across tissues thereby protecting against osteoarthritis and heart disease

OBJECTIVES

To investigate how ANP32A, previously linked to the antioxidant response, regulates Wnt signaling as unraveled by transcriptome analysis of Anp32a-deficient mouse articular cartilage, and its implications for osteoarthritis (OA) and diseases beyond the joint.

METHODS

Anp32a knockdown chondrogenic ATDC5 cells were cultured in micromasses. Wnt target genes, differentiation markers and matrix deposition were quantified. Wnt target genes were determined in articular cartilage from Anp32a-deficient mice and primary human articular chondrocytes upon ANP32A silencing, using qPCR, luciferase assays and immunohistochemistry. Co-immunoprecipitation, immunofluorescence and chromatin-immunoprecipitation quantitative PCR probed the molecular mechanism via which ANP32A regulates Wnt signaling. Anp32a-deficient mice were subjected to the destabilization of the medial meniscus (DMM) OA model and treated with a Wnt inhibitor and an antioxidant. Severity of OA was assessed by cartilage damage and osteophyte formation. Human Protein Atlas data analysis identified additional organs where ANP32A may regulate Wnt signaling. Wnt target genes were determined in heart and hippocampus from Anp32a-deficient mice, and cardiac hypertrophy and fibrosis quantified.

RESULTS

Anp32a loss triggered Wnt signaling hyper-activation in articular cartilage. Mechanistically, ANP32A inhibited target gene expression via histone acetylation masking. Wnt antagonist treatment reduced OA severity in Anp32a-deficient mice by preventing osteophyte formation but not cartilage degradation, contrasting with antioxidant treatment. Dual therapy ameliorated more OA features than individual treatments. Anp32a-deficient mice also showed Wnt hyper-activation in the heart, potentially explaining the cardiac hypertrophy phenotype found.

CONCLUSIONS

ANP32A is a novel translationally relevant repressor of Wnt signaling impacting osteoarthritis and cardiac disease.

[Flemish guideline for the prevention and use of seclusion and restraint]

BACKGROUND

International consensus states that seclusion and restraint should only be applied as briefly and as little as possible. However, audits by the Care Inspectorate show that this is not always the case in Flemish mental health care (MHC).

AIM

To describe the development of a multidisciplinary guideline for the prevention and application of seclusion and restraint in inpatient MHC, underpinned by both clinical-scientific and legal evidence.

METHOD

The GRADE method formed the basis for the development of the guideline. To integrate both types of evidence, two research phases were added. This article provides an overview of the challenges involved in implementing this interdisciplinary method.

RESULTS

There are gaps in both clinical-scientific and legal evidence. Nevertheless, the study resulted in a comprehensive guideline because we underpinned the recommendations with practice- and experience-based expertise of the Flemish stakeholders, and integrated the clinical-scientific and legal evidence.

CONCLUSION

Focus on implementation research and a clear legal framework for Flanders are necessary to safeguard the (human) rights of MHC users, also in the event of aggression and escalation.

Electronic visual analogue scales for pain, fatigue, anxiety and quality of life in people with multiple sclerosis using smartphone and tablet: a reliability and feasibility study

Objective:

To explore the reliability and feasibility of electronic visual analogue scales in people with multiple sclerosis (MS) and healthy individuals.

Design:

Cross-sectional observational study

Setting:

Clinical setting

Subjects:

Convenience sample of 52 people with MS and 52 matched healthy controls

Interventions:

NA

Main measures:

Participants scored 15 statements assessing fatigue, pain, anxiety and quality of life on an electronic visual analogue scale (eVAS), either using a smartphone or a tablet (randomly allocated). To check for test-retest reliability, statements were administered in two separate randomly ordered groups. Subjects completed a feasibility questionnaire.

Results:

Mean (SD) eVAS scores ranged from 35 (28.1) to 80 (22.1) in MS group, and from 57 (28.0) to 86 (13.2) in controls. Intra Class Correlations ranged from 0.73 to 0.95 in MS sample; 0.61 to 0.92 in controls. For most statements, Bland-Altman plots indicated no systematic error, but relatively large random error of the eVAS scores (exceeding 20mm). Considerable ceiling effects (i.e. better health) were found in healthy controls. Similar reliability was found among smartphone or tablet, different demographic groups and the experience-groups.

Conclusion:

Electronic visual analogue scales are reliable and useful for people with MS to register fatigue, pain, anxiety and quality of life.

Is adapted measured resection superior to gap-balancing in determining femoral component rotation in total knee replacement?

Obtaining a balanced flexion gap with correct femoral component rotation is one of the prerequisites for a successful outcome after total knee replacement (TKR). Different techniques for achieving this have been described. In this study we prospectively compared gap-balancing versus measured resection in terms of reliability and accuracy for femoral component rotation in 96 primary TKRs performed in 96 patients using the Journey system. In 48 patients (18 men and 30 women) with a mean age of 65 years (45 to 85) a tensor device was used to determine rotation. In the second group of 48 patients (14 men and 34 women) with a mean age of 64 years (41 to 86), an 'adapted' measured resection technique was used, taking into account the native rotational geometry of the femur as measured on a pre-operative CT scan. Both groups systematically reproduced a similar external rotation of the femoral component relative to the surgical transepicondylar axis: 2.4° (SD 2.5) in the gap-balancing group and 1.7° (SD 2.1) in the measured resection group (p = 0.134). Both gap-balancing and adapted measured resection techniques proved equally reliable and accurate in determining femoral component rotation after TKR. There was a tendency towards more external rotation in the gap-balancing group, but this difference was not statistically significant (p = 0.134). The number of outliers for our 'adapted' measured resection technique was much lower than reported in the literature.

Influence of ghrelin on the gastric accommodation reflex and on meal-induced satiety in man

Ghrelin increases gastric tone in the fasting state and enhances gastric emptying in gastroparesis. The aims of the study were to evaluate the effect of ghrelin on postprandial gastric tone and on meal-induced satiety in health. Ten healthy volunteers underwent a barostat study on two occasions. After determination of intra-abdominal pressure (minimal distending pressure, MDP), isobaric volume measurement was performed for 90 min at MDP + 2 mmHg. After 20 min, ghrelin (40 microg) or saline was administered i.v. over 30 min in a double-blind-randomized cross-over design, followed 10 min later by a liquid meal (200 mL, 300 kcal). Stepwise isobaric distentions (+2 mmHg per 2 min) were performed 60 min after the meal. Data (mean +/- SEM) were compared using paired Student's t-test and ANOVA. Separately, a satiety drinking test (15 mL min(-1) until satiety score 5) was performed on 10 subjects twice, after treatment with placebo or ghrelin. Ghrelin infusion significantly inhibited gastric accommodation (mean volume increase adjusted means 108.0 +/- 50 vs 23.0 +/- 49 mL, P = 0.03, ANCOVA with the premeal postinfusion volume as covariate) and reduced postprandial gastric volumes (197.2 +/- 24.6 vs 353.5 +/- 50.0 mL, P = 0.01). Pressures inducing perception or discomfort during postprandial gastric distentions were not altered. During satiety testing, ghrelin did not alter nutrient volume ingested till maximal satiety (637.5 +/- 70.9 vs 637.5 +/- 56.2 mL, ns). Ghrelin administered during the meal significantly inhibits gastric accommodation in health, but this is not associated with early satiation.

Characterization of myenteric neuropathy in the jejunum of spontaneously diabetic BB-rats

Decreased gastric expression and function of neuronal nitric oxide synthase (nNOS) has been proposed as a potential mechanism underlying diabetic gastroparesis. As gastric nNOS expression is vagally controlled, these changes might occur secondarily to vagal neuropathy. In addition, it is unclear whether other inhibitory neurotransmitters are also involved. We used the type 1 diabetic BioBreeding (BB)-rat model to study jejunal motor control and nNOS expression, which is independent of the vagus. Jejunal segments were used for in vitro contractility studies, and measurement of nNOS expression after 8 or 16 weeks of diabetes compared with age- and sex-matched controls. Unlike electrical field stimulation and acetylcholine (ACh)-induced contractions, non-adrenergic non-cholinergic (NANC) relaxations were significantly reduced in diabetic rats. In contrast to control rats, NANC relaxations in diabetic rats were N(omega)-nitro-L-arginine methyl ester (L-NAME) insensitive. Jejunal nNOS expression was significantly decreased in diabetic rats. Both in diabetic and in control animals, L-NAME resistant relaxations were sensitive to P(2)-receptor antagonists. In the jejunum of spontaneously diabetic rats, decreased nitric oxide responsiveness and decreased nNOS protein expression occur while purinergic transmission is unaffected. These findings indicate that nitrergic enteric neuropathy may be a primary dysfunction in diabetes, independent from vagal dysfunction.

Evolution of Vocal Fold Nodules from Childhood to Adolescence

SUMMARY

Bilateral (quasi) symmetrical lesions of the anterior third of the vocal folds, commonly called vocal fold nodules (VFNs) are the most frequent vocal fold lesions in childhood caused by vocal abuse and hyperfunction. This study evaluates their long-term genesis with or without surgery and voice therapy. A group of 91 postmutational adolescents (mean age, 16 years), in whom VFNs were diagnosed in childhood, were questioned to analyze the evolution of their complaints. Thirty four of them could be clinically reexamined by means of the European Laryngological Society-protocol, including a complete laryngological investigation and voice assessment. A total of 21% of the questioned group (n=91) had voice complaints persisting into postpubescence with a statistically significant difference (P <or= 0.001) between boys (8%) and girls (37%). VFNs were still present in 47% of the girls and 7% of the boys of the clinically evaluated group (n=34). Analysis of the data before and after puberty shows that the variables gender, allergy, and degree of dysphonia ("G") in childhood enable a fairly correct prediction of persisting voice complaints in adolescence (sensitivity of 89% and specificity of 67%). The results of this study show a clearly different evolution for both sexes, with significant higher long-term risks for dysphonic girls with allergy.

Discovery of a New Class of Macrocyclic Antagonists to the Human Motilin Receptor

A novel class of macrocyclic peptidomimetics was identified and optimized as potent antagonists to the human motilin receptor (hMOT-R). Well-defined structure-activity relationships allowed for rapid optimization of potency that eventually led to high affinity antagonists to hMOT-R. Potency and antagonist functional activity were confirmed both in functional and cell-based assays, as well as on isolated rabbit intestinal smooth muscle strips. Rapid access to this novel class of macrocyclic target structures was made possible through two efficient and complementary solid-phase parallel synthetic approaches, both of which are reported herein.

Altered gastrointestinal and metabolic function in the GPR39-obestatin receptor-knockout mouse

BACKGROUND & AIMS

The G-protein-coupled receptor GPR39 is a member of a family that includes the receptors for ghrelin and motilin. Recently the peptide obestatin was identified as a natural ligand for GPR39. The objective of this study was to gain insight into the biological function of the GPR39 receptor.

METHODS

GPR39(-/-) mice were generated and analyzed.

RESULTS

Endogenous GPR39 expression was detected in the brain (septum-amygdala) and the gastrointestinal system (parietal cells, enterocytes, neurons, and pancreas). Gastric emptying of a solid meal (measured by the (14)C octanoic breath test) in GPR39(-/-) mice was accelerated significantly with a gastric half-emptying time of 49.5 +/- 2.2 minutes compared with 86.9 +/- 8.4 minutes in GPR39(+/+) mice. A more effective expulsion of distally located pellets (30%-75% of length) was observed in the colon of GPR39(-/-) mice. Four hours after pylorus ligation, the volume of gastric secretion was increased significantly (GPR39(-/-): 638 +/- 336 microL; GPR39(+/+): 225 +/- 170 microL), but gastric acid secretion was unchanged. The mature body weight and body fat composition of GPR39(-/-) mice was significantly higher compared with GPR39(+/+) mice, but this was not related to hyperphagia because 24-hour food intake did not differ between both genotypes. In contrast, deficiency of the GPR39 receptor led to reduced hyperphagia after fasting. The cholesterol levels were increased significantly in the GPR39(-/-) mice.

CONCLUSIONS

Our data partially confirm and extend the described in vivo effects of obestatin and suggest that this peptide plays a functional role in the regulation of gastrointestinal and metabolic function through interaction with the GPR39 receptor.

Parallel Declines in Pollinators and Insect-Pollinated Plants in Britain and the Netherlands

Despite widespread concern about declines in pollination services, little is known about the patterns of change in most pollinator assemblages. By studying bee and hoverfly assemblages in Britain and the Netherlands, we found evidence of declines (pre-versus post-1980) in local bee diversity in both countries; however, divergent trends were observed in hoverflies. Depending on the assemblage and location, pollinator declines were most frequent in habitat and flower specialists, in univoltine species, and/or in nonmigrants. In conjunction with this evidence, outcrossing plant species that are reliant on the declining pollinators have themselves declined relative to other plant species. Taken together, these findings strongly suggest a causal connection between local extinctions of functionally linked plant and pollinator species.

Parallel declines in pollinators and insect-pollinated plants in Britain and the Netherlands

Despite widespread concern about declines in pollination services, little is known about the patterns of change in most pollinator assemblages. By studying bee and hoverfly assemblages in Britain and the Netherlands, we found evidence of declines (pre-versus post-1980) in local bee diversity in both countries; however, divergent trends were observed in hoverflies. Depending on the assemblage and location, pollinator declines were most frequent in habitat and flower specialists, in univoltine species, and/or in nonmigrants. In conjunction with this evidence, outcrossing plant species that are reliant on the declining pollinators have themselves declined relative to other plant species. Taken together, these findings strongly suggest a causal connection between local extinctions of functionally linked plant and pollinator species.

The contractile effect of the ghrelin receptor antagonist, D-Lys3-GHRP-6, in rat fundic strips is mediated through 5-HT receptors

Ghrelin is an orexigenic peptide present in the stomach with gastroprokinetic properties. Previous in vivo studies have shown that the ghrelin receptor antagonist, D-Lys(3)-GHRP-6, reduced food intake and delayed gastric emptying in rodents but these effects are at variance with the normal phenotype of the ghrelin knockout mice. To verify the specificity of the effects observed with D-Lys(3)-GHRP-6 this study aimed to investigate the pharmacology of D-Lys(3)-GHRP-6 in vitro. Rat fundic strips were suspended in a tissue bath and the contraction of strips to 10(-5) M of ghrelin, GHRP-6 or D-Lys(3)-GHRP-6 was measured isometrically in the absence and presence of blockers. Neither ghrelin, nor GHRP-6, induced significant contractions in the absence of electrical field stimulation thereby excluding the presence of ghrelin receptors on smooth muscle cells. In contrast D-Lys(3)-GHRP-6, induced a pronounced biphasic contraction of 13.9+/-1.8% and 40.5+/-3.2% relative to the response to 60 mM KCl. The contraction was blocked by the 5-HT(1,2) receptor antagonist methysergide and was markedly reduced by the 5-HT(2B) receptor antagonist, yohimbine, which also profoundly affected 5-HT induced contractions in fundic strips. The existence of 5-HT(2B) receptors in the fundus was confirmed by use of the 5-HT(2B) receptor agonist, BW 723C86. In contrast to ghrelin and GHRP-6, the ghrelin receptor antagonist, D-Lys(3)-GHRP-6, induced pronounced smooth muscle contractions in the rat fundus by interacting with 5-HT(2B) receptors. This may question the role of endogenous ghrelin in the effects observed with D-Lys(3)-GHRP-6 on food intake and gastric emptying in vivo.

Influence of motilin on gastric fundus tone and on meal-induced satiety in man: role of cholinergic pathways

BACKGROUND

Motilin agonists are strong gastroprokinetics, but their impact on symptoms in delayed gastric emptying has been disappointing. It has been speculated that it is due to the contractile effect of motilin agonists on the proximal stomach, but the pathway involved and the symptomatic consequences have been incompletely elucidated.

AIMS

To study whether motilin enhances proximal stomach tone and enhances meal-induced satiety and to evaluate whether this effect involves a cholinergic pathway.

METHODS

A gastric barostat was used to study, in healthy subjects, the effect of motilin (300 ng/kg/30 min i.v.) or saline on fasting gastric fundus tone and on post-prandial relaxation. To evaluate the involvement of a cholinergic pathway, atropine (12 microg/kg/h) was administered intravenously simultaneously with or before and during motilin infusion in the fasting state. Finally, a satiety drinking test was performed in 21 subjects twice after pretreatment with placebo or motilin and with placebo or atropine.

RESULTS

Administration of motilin caused a significant increase of fasting fundus tone expressed as decrease of the mean balloon volume (324 +/- 60 mL vs 213 +/- 62 mL, p < 0.05). Simultaneous administration of atropine and motilin did not generate a significant volume change (192 +/- 60 mL vs 181 +/- 83 mL, NS), but pretreatment with atropine alone induced a relaxation, and when motilin was added this revealed an ongoing contraction (192 +/- 24 mL vs 136 +/- 21 mL, p < or = 0.05). Motilin infusion also inhibited gastric accommodation (p < or = 0.05 vs placebo) and increased satiety during a satiety drinking test (p < or = 0.05 vs placebo).

CONCLUSIONS

Administration of motilin causes a contraction of the proximal stomach in humans and increases meal-induced satiety. The effect of motilin is atropine-resistant and involves a direct muscular pathway or a non-cholinergic neural pathway.

Expression of Ghrelin in nervous system and its cytoprotective action in rats

AIM: To investigate the expression of Ghrelin in brain, intestinal myenteric plexus and plasma and study its possible cytoprotective effect and mechanism on gastric mucosa against stress-induced ulcers.

METHODS: Seventy-six healthy male Wistar rats were divided into 6 groups randomly: cold-water restraint group (n = 10); intracerebroventricular (icv) injection of Ghrelin group (n = 24); icv injection of Ghrelin after subcutaneous injection of Nω-Nitro-L-arginine methylester (L-NAME) group (n = 8) and three matched control groups. The expression of Ghrelin in rat brain, intestinal myenteric plexus and plasma were detected by radio-immunoassay (RIA) and double staining of immunofluorescence and immunohistochemistry. The effect and mechanism of Ghrelin on gastric mucosa against stress-induced ulcer were analyzed using neurophysiologic methods.

RESULTS: Ghrelin-positive immunoreaction (IR) was observed in the small intestinal myenteric plexus and primarily cultured myenteric plexus neurons. Ghrelin-IR co-localized with choline acetyl transferase (ChAT), but not with nitric oxide synthase (NOS) or Calbindin (Calb) in the same myenteric plexus neurons. In comparison with that in its matched control group, the content of Ghrelin-IR in plasma was significantly decreased (198.3 ± 29.6 ng/L vs 141.7 ± 26.5 ng/L, P < 0.05), but increased in hypothalamus, medulla oblongata, pituitary and intestinal myenteric plexus (96.2 ± 18.1 pg/mg vs 153.2 ± 11.6 pg/mg, P = 0.006; 89.8 ± 16.5 pg/mg vs 144.4 ± 13.9 pg/mg, P = 0.007; 108.3 ± 11.9 pg/mg vs 198.2 ± 23.3 pg/mg, P = 0.002; 48.8 ± 12.8 pg/mg vs 86.2 ± 21.5 pg/mg, P = 0.02; respectively). The formation of stress ulcers was markedly inhibited by microinjection of Ghrelin into the ventricle with a dose-dependent manner (ulcer index: normal saline 86.7 ± 6.2; 50 ng Ghrelin 79.3 ± 10.7, P = 2.18; 500 ng Ghrelin: 61.3 ± 11.7, P = 0.04; 5 000 ng Ghrelin: 35.6 ± 10.8, P = 0.005). However, after a subcutaneous injection of L-NAME, the cytoprotective effect of Ghrelin disappeared.

CONCLUSION: Ghrelin co-localizes with ChAT in intestinal myenteric plexus neurons. The expression of Ghrelin changes in the central nerves system (CNS) and plasma while stress ulcer happens. Ghrelin in the CNS can protect gastric mucosa with a dose-dependent manner, which is probably related to the synthesis of nitric oxide.

Influence of ghrelin on interdigestive gastrointestinal motility in humans

BACKGROUND

Recent studies in animals have shown that ghrelin stimulates upper gastrointestinal motility through the vagus and enteric nervous system. The aim of the present study therefore was to simultaneously investigate the effect of administration of ghrelin on upper gastrointestinal motility and to elucidate its mode of action by measuring plasma levels of gastrointestinal hormones in humans.

MATERIALS AND METHODS

Nine healthy volunteers (four males; aged 22-35 years) underwent combined antroduodenal manometry and proximal stomach barostat study on two separate occasions at least one week apart. Twenty minutes after the occurrence of phase III of the migrating motor complex (MMC), saline or ghrelin 40 mug was administered intravenously over 30 minutes in a double blind, randomised, crossover fashion. Ghrelin, motilin, pancreatic polypeptide, glucagon, and somatostatin were measured by radioimmunoassay in blood samples obtained at 15-30 minute intervals. The influence of ghrelin or saline on MMC phases, hormone levels, and intraballoon volume was compared using paired t test, ANOVA, and chi(2) testing.

RESULTS

Spontaneous phase III occurred in all subjects, with a gastric origin in four. Administration of ghrelin induced a premature phase III (12 (3) minutes, p<0.001; gastric origin in nine, p<0.05), compared with saline (95 (13) minutes, gastric origin in two). Intraballoon volumes before infusion were similar (135 (13) v 119 (13) ml; NS) but ghrelin induced a longlasting decrease in intraballoon volume (184 (31) v 126 (21) ml in the first 60 minutes; p<0.05). Administration of ghrelin increased plasma levels of pancreatic polypeptide and ghrelin but motilin, somatostatin, and glucagon levels were not altered.

CONCLUSIONS

In humans, administration of ghrelin induces a premature gastric phase III of the MMC, which is not mediated through release of motilin. This is accompanied by prolonged increased tone of the proximal stomach.

Influence of ghrelin on gastric emptying and meal-related symptoms in idiopathic gastroparesis

BACKGROUND

Ghrelin, the endogenous ligand of the growth hormone secretagogue receptor, is released from the stomach. Animal studies suggest that ghrelin stimulates gastrointestinal motor activity.

AIM

To investigate the influence of ghrelin on gastric emptying rate and meal-related symptoms in idiopathic gastroparesis.

METHODS

In six patients with idiopathic gastroparesis, a breath test was used to measure gastric emptying rates (t(1/2)) for solids and liquids after administration of saline or ghrelin 40 microg/30 min in a double-blind, randomized fashion. At each breath sampling, the patient was asked to grade the intensity of six different symptoms (epigastric pain, bloating, postprandial fullness, nausea, belching and epigastric burning) and these were added to obtain meal-related symptom severity score.

RESULTS

Ghrelin significantly enhanced liquid emptying (t(1/2): 86 +/- 7 vs. 53 +/- 6 min, P = 0.02) and tended to enhance solid emptying (144 +/- 45 vs. 98 +/- 15 min, P = 0.06). Ghrelin pre-treatment significantly decreased cumulative meal-related symptom score (196 +/- 30 vs. 136 +/- 23, P = 0.04) and individual scores for fullness (55 +/- 8 vs. 39 +/- 8, P = 0.02), and for pain (40 +/- 8 vs. 16 +/- 5, P < 0.05).

CONCLUSIONS

In idiopathic gastroparesis, administration of ghrelin enhances gastric emptying and improves meal-related symptoms. These observations suggest a potential for ghrelin receptor agonists in the treatment of gastroparesis.

Initial staging of malignant melanoma by positron emission tomography and sentinel node biopsy

By a retrospective study and literature review we aimed to evaluate the accuracy of Sentinel Node Biopsy (SNB) and F-18-fluorodeoxyglucose positron emission tomography (PET) for early detection of lymph node metastases.

MATERIAL AND METHODS

Every patient presenting with a malignant melanoma without clinical lymph node involvement and a Breslow index over 1 mm or a recurrence was subjected to a preoperative PET scan and a sentinel node biopsy. Over a period of 10 months, 5 patients were included. They were submitted to conventional staging techniques, PET and SNB.

RESULTS

In none of the patients the PET scan showed signs of lymph node involvement or distant metastases. However, two patients, both with a Breslow index of 1.4, had micrometastases in the sentinel node.

CONCLUSION

Already in this small group of patients, PET scanning missed two metastases (40%). This is confirmed by several recent publications, stating that the resolution of positron emission tomography is about 5 mm and thus insufficient to detect micrometastases. Several larger series showed a sensitivity of PET to detect lymph node involvement of 15-50%. Therefore we conclude that PET is of limited use in these patients without palpable lymph nodes. Sentinel node biopsy however proves to be a useful tool and should be considered in the initial staging of malignant melanoma without palpable lymph node or distant metastases.

Comparison of the gastroprokinetic effects of ghrelin, GHRP-6 and motilin in rats in vivo and in vitro

Ghrelin and motilin form a new family of structurally related peptides. We compared the gastroprokinetic effects of ghrelin, the ghrelin receptor agonist, growth hormone releasing peptide 6 (GHRP-6), and motilin in rats in vivo and in vitro.

METHODS

Ghrelin, GHRP-6 or motilin (10-150 microg/kg) were injected i.p. and the effects on gastric emptying and transit were measured after intragastric application of Evans blue. In antral and fundic strips the effect of motilin, ghrelin or GHRP-6 was studied during electrical field stimulation (EFS) in the absence and presence of N(G)-nitro-l-arginine methyl ester hydrochloride (l-NAME) (300 microM).

RESULTS

Ghrelin and GHRP-6 but not motilin accelerated gastric emptying and transit in rats. Ghrelin was more potent than GHRP-6 and the dose-response relationship for ghrelin but not for GHRP-6 was bell-shaped. In fundic or antral strips, neural responses to EFS consisted of an on-relaxation that was reversed into a cholinergically mediated contraction by addition of the nitric oxide (NO)-synthase blocker, l-NAME. The post-stimulus off-contraction was cholinergically mediated. Under normal conditions, the ghrelin agonists reduced the on-relaxations in fundic strips and increased the cholinergic off-contractions in antral and fundic strips. The concentration response curves in muscle strips of the fundus were bell-shaped with maximal effects for ghrelin at 1.2 microM (on-responses) and 0.66 microM (off-responses) and for GHRP-6 at 0.50 microM (on-responses) and 0.26 microM (off-responses). No effects were observed with motilin between 1 nM and 0.1 microM. Studies in the presence of l-NAME confirmed the effect of the ghrelin agonists on cholinergic excitatory motor responses. No effects were observed with motilin under the different experimental conditions. The presence of growth hormone secretagogue receptor 1a transcripts in the strip preparations was confirmed by reverse transcriptase polymerase chain reaction (RT-PCR).

CONCLUSION

Ghrelin and GHRP-6 but not motilin accelerate gastric emptying and transit by activating cholinergic excitatory pathways in the enteric nervous system in addition to the known vagal pathways.

The therapeutic effect of the neuropeptide hormone somatostatin on Schistosoma mansoni caused liver fibrosis

Background

The neuropeptide somatostatin is one of the major regulatory peptides in the central nervous system and the digestive tract. Our recent work has delineated an association between fibrosis and low levels of endogenous somatostatin plasma levels in Schistosoma mansoni infected subjects. Based on these results this paper explores the therapeutic potential of somatostatin in a mouse model of hepatic fibrosis associated with S. mansoni infections.

Methods

Groups of outbred Swiss mice were infected with 100 S. mansoni cercariae, infection maintained till weeks 10 or 14, and then somatostatin therapy delivered in two regimens – Either a one or a two-day treatment. All animals were sacrificed one week after therapy and controlled for liver, spleen and total body weight. Circulating somatostatin levels in mice plasma were measured at the time of sacrifice by means of a radio-immuno assay. GraphPad Prism^® was used for statistical calculations.

Results

Somatostatin administration showed little toxicity, probably due to its short half-life. Total liver and spleen weights of S. mansoni infected animals increased over time, with no changes observed due to somatostatin therapy. Total body weights were decreased after infection but were not affected by somatostatin therapy. Snap frozen liver sections were stained with haematoxylin-eosin or Masson's trichrome to study parasite count, hepatocyte status, granuloma size and cellularity. After somatostatin treatment mean egg counts per liver section (43.76 ± 3.56) were significantly reduced as compared to the egg counts in untreated mice after 10 weeks of infection (56.01 ± 3.34) (P = 0.03). Similar significant reduction in parasite egg counts were also observed after somatostatin treatment at 14 weeks of infection (56.62 ± 3.02) as compared to untreated animals (69.82 ± 2.77)(P = 0.006). Fibrosis was assessed from the spectrophotometric determination of tissue hydroxyproline. Infection with S. mansoni caused increased hydroxyproline levels (9.37 ± 0.63 μmol at wk10; 9.65 ± 0.96 μmol at wk14) as compared to uninfected animals (1.06 ± 0.10 μmol). This significant increase in collagen content (P = 0.01; 0.007 respectively) marks the fibrosis observed at these time points. Treatment with somatostatin resulted in a significant decrease in hydroxyproline levels both at wk10 (4.76 ± 0.58 μmol) and at wk14 (5.8 ± 1.13 μmol) (P = 0.01; 0.03 respectively). Endogenous somatostatin levels were increased at wk10 (297 ± 37.24 pg/ml) and wk14 (206 ± 13.30 pg/ml) of infection as compared to uninfected mice (119 ± 11.99 pg/ml) (P = 0.01; 0.008 respectively). Circulating somatostatin levels in infected animals were not significantly affected by somatostatin treatment. Hepatocyte status remained unaltered and granulomas were not remarkably changed in size or cellularity.

Conclusion

Our experiments reveal an antifibrotic effect of somatostatin in schistosomiasis. We have previously shown that the somatostatin receptors SSTR2 and SSTR3 are present on the parasite egg and worms. We therefore hypothesize that somatostatin reduces either the number of parasite eggs or the secretion of fibrosis inducing-mediators. Our data suggest somatostatin may have therapeutic potential in S. mansoni mediated liver pathology.

Salvage of failed Sauvé-Kapandji procedure with an ulnar head prosthesis: report of three cases

Three failed Sauvé-Kapandji procedures were salvaged using an ulnar head prosthesis. At 7-22 month follow-up, all three patients were much improved. However, the stem of one implant subsequently fractured in a fall and this implant had to be removed.

An unusual metastatic motilin-secreting neuroendocrine tumour with a 20-year survival. Pathological, biochemical and motility features

Motilin-secreting neuroendocrine tumours have been rarely described. Immunohistochemical, biochemical and motility investigations were performed in a 62-year-old man with liver and bone metastases of a motilin-secreting neuroendocrine tumour originating from a rectal polyp removed 14 years previously. Symptoms related to liver metastases were reduced by a right hepatectomy whereas plasma motilin levels were decreased. The patient also underwent two operations for spinal cord decompression and survived 6 more years under medical treatment, mainly octreotide. Immunohistochemistry revealed predominant expression of motilin-containing cells, with rare cells expressing somatostatin and pancreatic polypeptide, and staining for only one panendocrine marker, neurone-specific enolase. A liver tumour extract contained 17.9 microg motilin per gram of tissue, which permitted to isolate and characterize human motilin, which was identical to porcine motilin. Plasma column gel chromatography revealed a main peak corresponding apparently to porcine motilin. The patient had no symptoms of disturbed motility. Gastric emptying and gastroduodenojejunal motility were found within normal limits. The absence of alterations of gut motility was perhaps related to sustained autonomous motilin production. The long evolution of this type of tumour suggests that plasma motilin determination should be added to the investigations for neuroendocrine tumours.

Rubinstein-Taybi syndrome caused by a De Novo reciprocal translocation t(2;16)(q36.3;p13.3)

Rubinstein-Taybi syndrome (RTS) is a multiple congenital anomalies and mental retardation syndrome characterized by facial abnormalities, broad thumbs, and broad big toes. We have shown previously that disruption of the human CREB-binding protein (CBP) gene, either by gross chromosomal rearrangements or by point mutations, leads to RTS. Translocations and inversions involving chromosome band 16p13.3 form the minority of CBP mutations, whereas microdeletions occur more frequently (approximately 10%). Breakpoints of six translocations and inversions in RTS patients described thus far were found clustered in a 13-kb intronic region at the 5' end of the CBP gene and could theoretically only result in proteins containing the extreme N-terminal region of CBP. In contrast, in one patient with a translocation t(2;16)(q36.3;p13.3) we show by using fiber FISH and Southern blot analysis that the chromosome 16 breakpoint lies about 100 kb downstream of this breakpoint cluster. In this patient, Western blot analysis of extracts prepared from lymphoblasts showed both a normal and an abnormal shorter protein lacking the C-terminal domain, indicating expression of both the normal and the mutant allele. The results suggest that the loss of C-terminal domains of CBP is sufficient to cause RTS. Furthermore, these data indicate the potential utility of Western blot analysis as an inexpensive and fast approach for screening RTS mutations.

Genotype-phenotype correlations in families with deletions in the von Hippel-Lindau (VHL) gene

Von Hippel-Lindau (VHL) disease is a hereditary tumor syndrome characterized by predisposition for bilateral and multi-centric hemangioblastoma in the retina and central nervous system, pheochromocytoma, renal cell carcinoma, and cysts in the kidney, pancreas, and epididymis. We describe five families for which direct sequencing of the coding region of the VHL gene had failed to identify the family-specific mutation. Further molecular analysis revealed deletions involving the VHL gene in each of these families. In four families, partial deletions of one or more exons were detected by Southern blot analysis. In the fifth family, FISH analysis demonstrated the deletion of the entire VHL gene. Our results show that (quantitative) Southern blot analysis is a sensitive method for detecting germline deletions of the VHL gene and should be implemented in routine DNA diagnosis for VHL disease. Our data support the previously established observation that families with a germline deletion have a low risk for pheochromocytoma. Further unraveling of genotype-phenotype correlations in VHL disease has revealed that families with a full or partial deletion of the VHL gene exhibit a phenotype with a preponderance of central nervous system hemangioblastoma.

Sequence and characterization of cDNA encoding the motilin precursor from chicken, dog, cow and horse. Evidence of mosaic evolution in prepromotilin

Motilin is involved in the regulation of the fasting motility pattern in man and in dog, but may have a different role in other species. Immunoreactive motilin has been demonstrated in several species, but the sequence is mostly unknown. The aim of this study was to isolate and sequence the cDNA encoding the motilin precursor from several mammalian species and from chicken. Total RNA was isolated from the duodenal mucosa of the chicken, dog, cow and horse. In each case single stranded cDNA was synthesized. Motilin cDNA fragments were amplified by PCR, ligated into a plasmid and cloned. Clones which were positive after screening with an appropriate (32)P-labeled probe were sequenced. The 5'- and 3'-ends were determined by the rapid amplification of cDNA ends (RACE) method. Analysis of the cDNAs revealed an open reading frame coding for 115 (chicken and cow), or 117 (dog and horse) amino acids. It consists of a 25 amino acid signal peptide, motilin itself, and a 68 (chicken and cow) or 70 (dog and horse) amino acid motilin associated peptide (MAP). As in all motilin precursors already sequenced (man, monkey, pig and rabbit), an endoproteinase cleavage site is present at Lys(23)-Lys(24). Comparison of all known sequences shows considerable identity in amino acid and nucleotide sequence of the signal peptide and motilin. However, the MAPs differ not only in length but also, more strongly, in amino acid and nucleotide sequence. Our study demonstrates that the N- and C-terminal regions of the motilin precursor have evolved at different rates, which is evidence for 'mosaic evolution'.

Involvement of two different pathways in the motor effects of erythromycin on the gastric antrum in humans

BACKGROUND

During the interdigestive state in humans, erythromycin 40 mg induces a premature activity front that starts in the stomach, while erythromycin 200 mg induces a prolonged period of enhanced antral contractile activity.

AIMS

To study the involvement of a cholinergic pathway in the motor effects of erythromycin using the muscarinic antagonist atropine and the neural 5-HT1 receptor agonist sumatriptan.

METHODS

In 30 healthy volunteers, fasted antroduodenojejunal motor activity was studied by stationary manometry. Placebo (n = 10), atropine (15 micrograms/kg intravenous bolus plus 15 micrograms/kg/h over 30 minutes; n = 10), or sumatriptan (6 mg subcutaneously; n = 10) was administered, followed by infusion of erythromycin 40 mg or 200 mg.

RESULTS

After placebo, erythromycin 40 mg induced a premature activity front with gastric onset after 19.1 (1.7) minutes in all volunteers. After atropine, erythromycin 40 mg failed to induce a premature activity front during a 60 minute period in all volunteers (p < 0.001), while sumatriptan prevented the induction of a premature activity front during a 60 minute period in all but one volunteer (p < 0.005). The number of antral contractions and their mean amplitude in the 60 minutes after erythromycin 200 mg did not differ significantly after atropine or sumatriptan versus placebo.

CONCLUSIONS

The antral motor effects of erythromycin in humans are mediated via different pathways. The induction of a premature activity front is mediated through activation of an intrinsic cholinergic pathway, while the induction of enhanced antral contractile activity may be mediated via a pathway potentially involving activation of a muscular receptor.

Correlation between concentrations of melatonin in saliva and serum in patients with delayed sleep phase syndrome

Exogenous melatonin, which can be used to treat certain circadian rhythm disorders, maximally advances delayed rhythms when administered 5 hours before the endogenous melatonin starts to increase. The time of the start of the endogenously melatonin is defined as Dim Light Melatonin Onset (DLMO). The DLMO concentration has been defined in serum to be 10 pg/ml. Because of the greater practicability of frequent saliva sampling over blood sampling, we have validated radioimmunoassay (RIA) measurements of melatonin in saliva in patients diagnosed as suffering from a typical circadian rhythm disorder: Delayed Sleep Phase Syndrome (DSPS). Based on these results we have defined the equivalent salivary DLMO concentration to be 4 pg/ml.

5-Hydroxytryptamine-1 receptor activation inhibits endocrine pancreatic secretion in humans

The selective 5-hydroxytryptamine-1 receptor agonist sumatriptan inhibits exocrine pancreatic function in humans. No data are available on the effect of sumatriptan on fasting and postprandial endocrine pancreatic function in humans. To elucidate the influence of 5-hydroxytryptamine-1 receptor activation by sumatriptan on endocrine pancreatic function and blood glucose homeostasis, we determined plasma levels of somatostatin, glucagon, pancreatic polypeptide, insulin, and C-peptide before and after subcutaneous administration of sumatriptan (6 mg) in seven healthy volunteers, and we measured blood glucose and insulin plasma levels during an oral glucose tolerance test after placebo and after subcutaneous administration of sumatriptan (6 mg) in seven healthy volunteers. Sumatriptan significantly decreased the mean plasma levels of somatostatin, glucagon, pancreatic polypeptide, insulin and C-peptide (P < 0.001) and also significantly decreased mean and peak plasma levels of insulin after an oral glucose challenge (P < 0.02 and P = 0.04, respectively) without affecting glucose homeostasis. From our study, we speculate that activation of the 5-hydroxytryptamine-1 receptor inhibits endocrine pancreatic secretion.

Actions of the 5-hydroxytryptamine 1 receptor agonist sumatriptan on interdigestive gastrointestinal motility in man

BACKGROUND

Pharmacological studies of the enteric nervous system have shown the presence of several subtypes of 5-hydroxytryptamine (5HT) receptor, which might be involved in control of the migrating motor complex.

AIMS

To study the effect of sumatriptan, an agonist of enteric neuronal 5HT1p receptors, on interdigestive motility in man.

SUBJECTS AND METHODS

In 12 healthy subjects, interdigestive motility was recorded manometrically in the upper gastrointestinal tract. In seven subjects blood samples were drawn every 15 minutes for radioimmunoassay of motilin and somatostatin. After two phase 3s of the migrating motor complex, 6 mg of sumatriptan was administered subcutaneously. Recording continued until two more phase 3s had occurred.

RESULTS

Sumatriptan induced a premature phase 3 in the jejunum after a median of 10 (8) minutes. The duration of the migrating motor complex cycle was shortened at the expense of phase 2. After sumatriptan, plasma somatostatin concentrations were reduced and gastric phase 3s were suppressed, although median motilin concentrations and the occurrence of plasma motilin peaks were not affected. Phase 3s of the migrating motor complex preceding sumatriptan were associated with motilin peaks, while phase 3s after sumatriptan were not. Furthermore, pretreatment with sumatriptan prevented the induction of a gastric phase 3 by the motilin agonist erythromycin.

CONCLUSIONS

Administration of the 5HT1P receptor agonist sumatriptan induces a premature intestinal phase 3, suppresses gastric phase 3s, prevents induction of a gastric phase 3 by erythromycin, and reduces plasma somatostatin concentrations.

Isolation and sequencing of the cDNA encoding the motilin precursor from sheep intestine

The nucleotide sequence of sheep prepromotilin has been determined from cDNA clones. The nucleotide sequence revealed an open reading frame of 345 nucleotides encoding 115 amino acids. The amino acid sequence deduced from the nucleotide sequence consists of a 25 amino acid signal peptide, followed by the 22 amino acid motilin sequence, an endoproteinase cleavage site (Lys23-Lys24) and a 66 amino acid motilin associated peptide (MAP). Compared with human and pig motilin we observed two substitutions at positions 10 (Leu-->Val) and 19 (Asn-->Tyr). The second one may explain the poor cross-reactivity of ovine motilin with C-terminally directed antibodies against porcine motilin. The sheep motilin precursor exhibits the same structure as the motilin precursors from rabbit, pig and man. However, while there is considerable identity in the amino acid sequences as well as in the nucleotide sequences of the signal peptide and motilin, the MAP strongly differs between the species. This may be a result of 'mosaic evolution' at the molecular level.

Comparison between vasoactive intestinal polypeptide and pituitary adenylate cyclase activating polypeptide levels in neuroblastoma tumour tissues

Vasoactive intestinal polypeptide (VIP) is reported to exert an autocrine control on neuroblastoma cell tumours: VIP is produced by the tumour and stimulates cell differentiation. This study tested the hypothesis that the parent peptide; the pituitary adenylate cyclase activating polypeptide (PACAP) may have a similar role. It was found that PACAP mRNA and PACAP were expressed in 12/12 tumours; it was also observed that PACAP receptor mRNA and functional PACAP receptors were expressed in 12/12 and 5/9 tumours, respectively. VIP mRNA and VIP were detected in 9/12 tumours. VIP receptor mRNA was expressed in 5/12 tumours and functional VIP receptors were never demonstrated. The tumours having the highest VIP levels also had the highest PACAP contents and were associated with a watery diarrhoea syndrome due to activation of intestinal VIP receptors. As PACAP recognizes the PACAP receptors and the VIP receptors with the same high affinity it may contribute to the syndrome and is a likely candidate for an autocrine control of neuroblastoma cell growth and differentiation.

Purification and amino acid sequence of human motilin isolated from a motilin containing liver metastasis

The acid extract of a liver metastasis from a patient with elevated plasma motilin levels contained large quantities of motilin (3.37 micrograms/ml). The extract was concentrated on a C18-column and motilin was isolated by gel chromatography (Sephadex G-50) followed by cation ion exchange chromatography (HR5/5 Mono-S) and three successive steps of reverse phase chromatography (Nucleosil 300-5 C18). The pure peptide was sequenced and the identity of porcine and human motilin was confirmed. This is the first report of a tumor containing large amounts of motilin.

Synthesis and characterization of site-specific biotinylated probes for the motilin receptor

The solid-phase synthesis of two porcine motilin derivatives, specifically biotinylated on the side chain of Lys20, was accomplished by preactivation of the protected amino acids N alpha-(9-fluorenylmethoxycarbonyl)-N epsilon-biotinyl-L-lysine and N alpha-(9-fluorenylmethoxycarbonyl)-N epsilon-[N-(biotinyl)-6-aminohexanoyl]-L-lysine with BOP/HOBt/DIEA (1:1:2.5) followed by coupling to the support-bound peptide substrate. The biotin moiety was stable to TFA cleavage and repetitive cycles of acylation, as evidenced by the high level of purity (> 80%) of the crude peptides. This direct synthetic approach complements existing orthogonal protection strategies for the site-specific biotinylation of peptides. The derivatized peptides were purified by RP-HPLC and characterized by mass spectral and amino acid analysis. In binding studies using a rabbit antral smooth muscle homogenate, both [Leu13, Lys20 (N epsilon-biotinyl)]porcine motilin (3) and [Leu13, Lys20 (N epsilon-[N-(biotinyl)-6-aminohexanoyl])]porcine motilin (4) possessed nearly equal affinities for the motilin receptor (IC50 = 0.89 and 1.2 nM, respectively) as native porcine motilin (1) (IC50 = 0.76 nM). The biotinylated peptides were also highly potent in tissue bath assays employing rabbit duodenal smooth muscle segments. In contrast, commercially available [N alpha-biotinylPhe1]porcine motilin (5) had markedly lower affinity in the binding assay (IC50 = 30 nM). The relative bioactivities of these receptor probes are in accord with previous synthetic studies on motilin which demonstrated the importance of the amino-terminal segment in the high affinity interaction between the peptide and its receptor. Analog 3 retained high affinity for the motilin receptor in the presence of avidin. Therefore, this peptide is expected to be a valuable tool for the isolation and identification of motilin receptors.

5-hydroxytryptamine-3 receptors are involved in the initiation of gastric phase-3 motor activity in humans

BACKGROUND

5-hydroxytryptamine-3 (5-HT3) receptor antagonists inhibit gastric phase-3 motor activity in the dog. This study examined the role of 5-HT3 receptors in the generation of gastric phase 3 of the migrating motor complex in humans.

METHODS

Interdigestive motor activity was recorded manometrically in 16 subjects before and after administration of ondansetron, a selective 5-HT3 receptor antagonist. Plasma motilin values were also assayed in 7 individuals. The incidence of gastric activity fronts before and after ondansetron was compared with a control group that had not received ondansetron. The ability of erythromycin to induce a gastric activity front in the presence of ondansetron was also evaluated in 7 subjects.

RESULTS

The incidence of gastric activity fronts was 69% before ondansetron vs. 19% after ondansetron. In contrast, in the control group there was no significant change in the incidence of gastric activity fronts over time. Activity fronts preceding ondansetron were associated with motilin peaks while activity fronts after ondansetron were not. Despite the previous administration of ondansetron, erythromycin induced gastric activity fronts in 89% of cases.

CONCLUSIONS

Selective antagonism of 5-HT3 receptors suppresses the gastric component of phase-3 motor activity and simultaneously suppresses plasma motilin peaks. The results suggest that the suppression of gastric activity fronts is achieved via the suppression of plasma motilin peaks because in the presence of ondansetron a motilin agonist like erythromycin restores the gastric phase 3.

Effect of erythromycin on gastric motility in controls and in diabetic gastroparesis

The effect of three doses of erythromycin on interdigestive gastrointestinal motility and on plasma motilin levels was studied in healthy volunteers and patients with diabetic gastroparesis. Abnormalities of interdigestive motility were observed in 40% of the patients. In healthy volunteers, 40 mg erythromycin elicited a premature phase 3 that started in the stomach. In contrast to the spontaneous gastric phase 3, this erythromycin-induced phase 3 was not accompanied by a motilin peak. In patients with diabetic gastroparesis, 40 mg erythromycin induced a premature phase 3 in three patients, no response in one patient, and a burst of antral contractions in another patient. Doses of 200 and 350 mg erythromycin elicited a burst of antral phase-3-like contractions in both volunteers and patients, which was not accompanied by a motilin peak. This phase-3-like activity did not migrate to the small intestine and was not followed by a phase 1, but by a prolonged period of antral contractile activity. The number and amplitude of antral contractions after 200 or 350 mg erythromycin were significantly higher than after 40 mg. The motor patterns induced by different doses of erythromycin offer potential therapeutic applications.

Intravenous erythromycin dramatically accelerates gastric emptying in gastroparesis diabeticorum and normals and abolishes the emptying discrimination between solids and liquids

Erythromycin, a macrolide antibiotic, has recently been shown to have a motilin like effect on gastrointestinal muscle strips. In this study, we have evaluated the effect of erythromycin on patients with delayed gastric emptying and healthy subjects using the dual radionuclide technique. Twelve patients with gastroparesis diabeticorum and ten healthy age- and sex-matched controls were studied. Gastric emptying of solids and liquids was determined using 99mTc-SC scrambled egg and 111In-DTPA in water. Following a baseline study and on a separate day, each patient and control received a 15-min i.v. perfusion of erythromycin starting at meal ingestion. Eleven out of the 12 patients were restudied after a 3-wk oral administration. In patients and controls, i.v. erythromycin dramatically accelerated gastric emptying of both solids and liquids which were emptied at the same rate. After chronic oral administration, solid and liquid emptying remained significantly accelerated. Erythromycin appears to be a very powerful gastrokinetic drug. Derived compounds with the gastrokinetic effect and without the antibiotic activity could be useful in dyspeptic patients with delayed gastric emptying.

Stress-induced changes in gastric emptying, postprandial motility, and plasma gut hormone levels in dogs

The influence of acoustic stress on postprandial gastrointestinal motility, gastric emptying, and plasma gastrin, pancreatic polypeptide, motilin, and somatostatin was evaluated in conscious dogs. Six dogs were equipped with strain-gauge transducers and were exposed from 1-3 h after the meal to prerecorded music (80-90 dB broad frequency noise), which produced a significant (p less than or equal to 0.05) lengthening of the gastric (31.2%) and jejunal (37.0%) postprandial pattern. In 4 other dogs with gastric cannula, a 2-h session of acoustic stress beginning just after eating a radiolabeled standard meal induced a slowing of gastric emptying of both liquid (45.7%) and solid (47.1%) phases of the test meal when measured 0.5 h after feeding. In contrast, when measured 2 h after feeding, similar values of gastric emptying of liquids and solids were observed in stressed and control animals. Compared with controls, the postprandial increases of plasma gastrin and pancreatic polypeptide levels were significantly enhanced in stressed animals and occurred early (15 min after the meal). Although postprandial decrease in plasma motilin was unchanged by acoustic stress, the rise in plasma somatostatin level was significantly (p less than or equal to 0.05) prolonged in stressed dogs. These results indicate that acoustic stress affects gastric and intestinal postprandial motility in dogs, delaying the recovery of the migrating motor complex pattern, inducing a transient slowing of gastric emptying, and enhancing the feeding-induced release of gastrin, pancreatic polypeptide, and somatostatin. Such hormonal changes might be due to a direct effect of stress rather than being the consequence of acoustic stress-induced slowing of gastric emptying.

Erythromycin is a motilin receptor agonist

Erythromycin A (EMA) is a potent stimulator of gastrointestinal motor activity. In vitro studies suggest that it mimics motilin, a peptide that stimulates motor activity in human and in rabbit via smooth muscle receptors. We have compared the in vitro contractile effect of EMA and two derivatives, 8,9-anhydro-EMA-6,9-hemiketal (EM201) and EMA N-oxide, on rabbit duodenal smooth-muscle strips with their ability to displace iodinated motilin bound to crude smooth-muscle membrane fractions. The concentrations required to induce 50% of the maximum contractile response to a supramaximal dose of acetylcholine were 5.0 x 10(-8), 2.0 x 10(-6), and 1.0 x 10(-4) M for, respectively, EM201, EMA, and EMA N-oxide. The concentrations required to displace 50% of the labeled motilin were, in the same order, 1.0 x 10(-8), 1.3 x 10(-7), and 4.0 x 10(-6) M. Both parameters were well correlated. The dose-response curve of the EMA was parallel to that of motilin and the effects of motilin and EMA were additive. Contractions induced by EMA were insensitive to pretreatment with tetrodotoxin or atropine. EMA had no effect on muscle strips of rat or dog duodenum but did induce contractions in human strips. EMA was totally ineffective on ileal preparations, which are also unresponsive to motilin and in which motilin binding is absent. EMA has therefore the same regional and species specificity as motilin. We conclude that EMA is a motilin receptor agonist.

Role of gastrin and insulin in postprandial disruption of migrating complex in dogs

The duration of the disruption of the interdigestive migrating myoelectric complex (MMC) by various test meals in dogs was correlated with changes in serum gastrin and insulin levels. The test meals consisted of milk protein, sucrose, arachis oil and medium chain triglycerides (MCT). Intravenous infusions of glucose 20% were also used. Electrical activity of the small intestine was registered by means of electrodes implanted over the entire length of the gut. Hormones were assayed by radioimmunoassay techniques. The insulin level rose significantly after both the glucose infusion and the sucrose meal. The rise was small after the milk protein meal and nothing after arachis oil and MCT. Gastrin level was not changed by arachis oil or MCT and rose slightly after sucrose and milk protein. The MMC was not disrupted by glucose infusions, but was disrupted for 5--7 h by archis oil and for 6--12 h by MCT. We conclude that in dogs neither gastrin nor insulin have an important role in the mechanism of disruption of the MMC after feeding.

Evaluation of the discriminative power of lipidophoresis by discriminant analysis using a simple quantitative method of agarose lipidophoresis

A simple, reproducible and quantitative method for separation of lipoproteins in agarose is presented. The validity of the results is shown by comparison with gravimetric analysis of fractions separated by ultracentrifugation in a discontinuous NaCl-KBr gradient. Results for a large group of normals and of patients with various lipid disorders are presented, and discriminant analysis is used to evaluate objectively the potential of lipidophoresis in the classification of hyperlipoproteinemias. It is shown that quantitative lipidophoresis gives as much information as the determination of cholesterol and triglycerides, for classification purposes.

The inhibition of lysozyme by bile acids

The effect of bile acids on the bacteriolytic activity of lysozyme towards Micrococcus lysodeikticus was studied in vitro. All bile acids tested inhibited lysozyme activity. Conjugated bile acids were better inhibitors than their unconjugated homologs and sulfation resulted in still stronger inhibition. A study of UV-difference spectra of bile acid-lysozyme mixtures suggests that bile acids distort the tertiary structure of the enzyme. The inhibition-concentration curves of micelle-forming bile acids were bell-shaped, and peak inhibition was apparently related to the critical micellar concentration. The inhibition-concentration curves of sulfated bile acids, which do not form micelles, are characterized by a plateau of maximal inhibition. A mechanism of lysozyme activation by bile acid micelles is proposed. Our results illustrate the complex interactions between antibacterial compounds in the gut. As bile acids are known to inhibit lipase activity as well, these studies suggest that bile acids may have an important influence on intestinal enzyme activity in general.