Gastric motor activity in Varanus griseus lizards

Motor activity of the stomach in V. griseus consists of contractions which follow the rhythm of 7-10 movements per 15 min. In contrast to tortoises, no periodic hunger activity of the stomach was observed in the lizard. Subcutaneous injection of 0.6% NaCl solution does not affect contractile activity of stomach muscles. Pilocarpine in a dose 100 microgram/kg of body weight did not change the gastrogram, doses 500 and 1,000 microgram increased the frequency and the amplitude of contractions. Atropine in a low dose (100 microgram) did not affect stomach movements. Doses 500, 1,000 and 2,000 microgram induced biphasic response. Sunflower-seed oil (10 ml) decreased twofold the frequency and the amplitude of contractions within 45-60 min.     

The effects of surgery on gastrointestinal motor activity

Gastrointestinal surgical procedures have the potential to disrupt motor activity in various organs of the gastrointestinal tract or, indeed, throughout the entire alimentary canal. Several of these motor effects have important clinical consequences and have also served to advance our understanding of the regulation of gastrointestinal motor activity. This review will focus, in particular, on the effects of surgery on the small intestine, and will attempt to emphasize the implications of these studies for our understanding of small intestinal motility, in general.     

Gastric myoelectric and motor activity in dogs after isoflurane anesthesia

To characterize the effects of isoflurane on gastric motility, gastric electrical and contractile activities were assessed in six healthy adult dogs before and after recovery from anesthesia. Baseline recordings (fasting and fed state) were obtained in unanesthestized dogs 8 days after implantation of serosal electrodes and strain-gauge force transducers. After an overnight fast, dogs were anesthetized with 1.3 minimum alveolar concentration (MAC) isoflurane for 4.5 hours (approximately 6 MAC hours). No other anesthetic or sedative drugs were administered. During anesthesia, ventilation was mechanically controlled to maintain arterial carbon dioxide tension at 36 +/- 4 mm Hg. Gastric electrical and contractile activities (fasting and fed state) were recorded again 18 hours after recovery from isoflurane anesthesia. Recordings were analyzed to determine gastric slow-wave frequency, presence of slow-wave dysrhythmias, slow-wave propagation velocity, coupling of contractions to slow waves, a motility index based on relative contractile amplitudes, and onset and duration of contractions after a standardized meal. The only variable that was significantly decreased 18 hours after 6 MAC hours of isoflurane anesthesia was the gastric motility index during fasting-state phase III. This decrease was not apparent in the fed-state test periods. Our results suggest that, with the exception of gastric motility index during fasting-state phase III, variables for gastric electrical and contractile activities in dogs are unaffected by isoflurane 18 hours after anesthesia.     

Gastric motor and sensory function testing

Structural properties of an equilibrium intermediate formed upon urea-induced unfolding of more ordered staphylococcal nuclease A-forms (A2 and A3) are studied. The effect of association on the structural properties and conformational stability of this unfolding intermediate is also considered. A close structural similarity (including tendency for association) is shown between this intermediate and the least ordered A1-form, induced in the acid-unfolded nuclease by moderate sulfate or chloride concentrations.     

Gallbladder pressure-volume response to gastrointestinal hormones

The pressure-volume (PV) response of the opossum gallbladder was studied under basal conditions and after the continuous intravenous infusion of gastrin I, secretin, and cholecystokinin (CCK). The hormone effects were examined individually and in combination. The unstimulated gallbladder was capable of accommodating increases in intraluminal volume with only slight changes in intraluminal pressure. Cholecystokinin significantly increased the pressure recorded from the gallbladder. The pressure generated depended on the concentration of CCK and the intraluminal volume. Gastrin I had no independent effect on the PV response of the gallbladder but reduced the stimulatory affect of CCK. Secretin, alone, decreased the PV response of the gallbladder. Secretin also antagonized the stimulatory response to CCK. These findings suggest that the regulation of gallbaldder motor function and pressure generation exclusive of neural input, may depend on the interaction of CCK with gastrin and secretin and the intraluminal volume of the organ at the time of stimulation.     

Structural similarities among gastrointestinal hormones and related active peptides

The amino acid sequences of gastrointestinal hormones were compared in fragments of variable spans. Similarities within each of three peptide groups are extensive, but non-unique alignments were also noticed in the glucagon group. Use of different spans demonstrated that structural similarities are unevenly distributed in the gastrin family. Correct phasing was detected even for proteins with few identities and multi-shifted alignments (alcohol dehydrogenases). Tests for alignments among different groups of peptides revealed similarities between bombesin and glucagon or secretin, as well as between caerulein and litorin. Recently determined extended structures suggested the presence of a few deletions/insertions close to the middle of the molecules (two such positions missing in the gastrin-releasing peptide in relation to glucagon). The alignments appear to structurally link large groups of peptide hormones and active peptides. Similarities concentrate in the C-terminal parts, and gaps in the middle. These facts are consistent with known correlations with bioactivities. They also suggest the possibility of evolutionary connections among different peptides as well as corresponding relationships among their receptors.     

Gastric lipoma presenting as upper gastrointestinal obstruction

Effects of dipterex, temephos, and chlorpyrifos resistance on the relative fitness of Culex pipiens pallens (L.) were evaluated by examining developmental and reproductive characteristics. Age-specific life tables of Dip-R- (dipterex), Tmo-R- (temephos), and Chl-R- (chlorpyrifos) resistant strains were compared with the susceptible strain to determine relative fitness based on population trend indices (I). The 3 organophosphate-resistant strains possessed reproductive and developmental disadvantages involving fecundity and survival relative compared with the susceptible strain, with relative fitness values of 0.465, 0.520, and 0.501, respectively. These results are discussed in relation to the reversal from resistance to susceptibility in natural populations of mosquitoes.     

Effect of some gastrointestinal hormones on antral, small intestinal and caecal myoelectrical activity in the conscious miniature pig

The effect of i.v. infusion of gastrin (CCK-4), cholecystokinin (CCK-8) and pancreatic polypeptide (PP), 20 and 200 ng/kg/min for 1 h, on gastrointestinal electrical activity and arterial pressure was studied in conscious miniature pigs. During infusion of CCK-8 a transient hypertension was observed. In the antrum, the 3 peptides provoked an increase in slow wave activity and a decrease in spike activity. In the intestine, CCK-8 induced an increase in ileal spiking activity, whereas infusion of PP resulted in an increased frequency of long spike bursts in the caecum.     

Clinical relevance of gastrointestinal hormones: emerging interest in hypergastrinemia

Vasovagal syncope has been ascribed to the vagal excitation and the sympathetic inhibition induced reflexly by mechanical stimulation of receptors in the ventricles. In this case report we describe a vasovagal syncope with bradycardia triggered by a reduction in venous return obtained via mild lower body negative pressure, in a patient with cardiac denervation due to heart transplantation. This suggests that the mechanisms involved in this phenomenon may not exclusively depend on a reflex originating from ventricular receptors. It also suggests that non-neural factors may be involved in the genesis of the bradycardia.     

Telomerase activity in gastrointestinal stromal tumors

BACKGROUND: Telomerase activity has been observed in 80-90% of carcinomas derived from various organs. However, to the authors' knowledge this report is the first assessment of telomerase activity in gastrointestinal stromal tumors (GISTs). METHODS: Telomerase activity was analyzed by the telomerase repeat amplification protocol assay in 29 tumors from 26 patients (23 primary tumors from 22 patients, 1 pair of primary and metastatic tumors from 1 patient, and 4 metastatic tumors from 3 patients). Phenotypes, tumor cell proliferation, and overexpression of p53 protein were evaluated immunohistochemically. RESULTS: Seven of 24 primary tumors (29%) and 5 of 5 metastatic tumors (100%) showed telomerase activity. Telomerase activity positive (+) GISTs were significantly larger (P < 0.05) and showed a significantly higher rate of proliferation than telomerase activity negative (-) tumors (P < 0.0001). All telomerase activity (+) GISTs were classified histologically as high risk tumors. Conversely, 15 of the 17 telomerase (-) GISTs were classified histologically as low risk tumors (P < 0.0001). With regard to p53 immunoreactivity, two and seven telomerase activity (+) tumors showed diffuse and sporadic positivity, respectively, whereas only five telomerase activity (-) tumors showed only focal or sporadic positivity. Telomerase activity was correlated significantly with poor prognosis (P < 0.05) in the patients in whom the primary GISTs were evaluated (n = 23). CONCLUSIONS: Telomerase activity may be a useful marker for evaluating the malignant potential of GIST. A distinct subgroup of GISTs is a target for therapy with a telomerase inhibitor.     

Gastric emptying and lingual lipase activity in cystic fibrosis

To identify gastric factors likely to contribute to fat maldigestion and malabsorption in cystic fibrosis (CF), gastric emptying time, secretion rate, and preduodenal lipolytic activity were studied. Gastric emptying of a liquid test meal and gastric acid secretion were determined in five CF teenagers with pancreatic insufficiency and in five healthy controls. During the first hr, the rate of gastric emptying exhibited a linear pattern in both CF patients and controls. Neither the emptying time nor the gastric secretion rate was different. Lingual lipase activity was measured in eight other CF patients with pancreatic insufficiency and in eight controls. Lipase activity was higher (P less than 0.05) in CF patients than in controls with values (mean +/- S.E.) of 34.48 +/- 11.59 and 12.65 +/- 5.60 mumole butyric acid min-1 ml-1, respectively. No correlation with age or body surface was observed. Intragastric lipolysis of a butterfat triglyceride test meal was fast in both groups, but more extensive (P less than 0.05) in CF patients than in controls. The data show that in CF with pancreatic insufficiency, gastric factors contributing to the first step of fat digestion are preserved. In fact, lingual lipase activity was found to be increased, and a more complete intragastric lipolysis was documented.     

Plasma arginine vasopressin and motor activity in major depression

The aim of this study was to test whether the effect of surfactant treatment on lung function in a surfactant-deficient animal model can be influenced by the rate at which surfactant is administered. Surfactant deficiency was induced in 18 New Zealand white rabbits (weighing approx. 1 kg each) by lung lavage with normal saline. The arterial/alveolar oxygen ratio (a/A ratio), functional residual capacity (FRC), dynamic compliance of the respiratory system (Crs), tidal volume (V(T)), alveolar portion of the tidal volume (V(A)) and arterial P(CO2) (P(a,CO2)) were measured before and after lavage and 15, 30, 60, 90, and 120 min after administration of a single dose of surfactant (Survanta, 100 mg/kg). Two surfactant administration protocols were compared over a 2-h interval: an infusion lasting 4 min and an infusion over 2 min. Both administrations were given during continuous mechanical ventilation. The six lung function and gas exchange parameters improved significantly following surfactant administration over 2 min compared with a control group. However, only the a/A ratio and V(A) improved following the 4-min protocol. Comparison of the two intervention protocols yielded significantly differences in V(A) and P(a,CO2), favoring the shorter administration. These results support the hypothesis that fast (2 min) administration of surfactant will improve its distribution to formerly collapsed alveoli and results in better lung function, improved ventilation, and (to a lesser extent) better oxygenation than prolonged infusions (4 min).     

Oscillatory brain activity during a motor task

Changes in spectral power in neuromagnetic fields associated with a manual task requiring a high level of sensorimotor integration (SMI) were investigated by analysing spontaneous, non-invasively recorded activity during motor preparation (WAIT), task performance (SMI), and control (REST) conditions in four healthy, right-handed human subjects. Neuromagnetic fields were recorded over the left sensorimotor cortex using a 37-channel instrument. In all subjects, a prominent narrow-band motor preparation rhythm centered near 19 Hz was consistently observed during the WAIT state. During SMI, mean relative increases in 26-30 Hz activity appeared in two of the subjects, paralleling gamma band enhancement recently observed during SMI in monkeys.     

Colonic motor activity in women during sleep

Regulators of G-protein signalling (RGS) are recently identified proteins that shorten the lifetime of the activated G protein. We now show that rat cardiac myocytes express mRNA for at least 10 RGS. The mRNA for RGS-r is barely detectable in rat ventricles, but increases more than 20-fold during the 60- to 90-min process of isolating ventricular myocytes, and after 90 min of culture of atrial pieces in medium with Ca2+. Both in myocytes and in atria, the rise in RGS-r is transient. The mRNA for cardiac RGS5, but not RGS-r, is developmentally regulated. These studies suggest that rapid regulation of RGS levels may be a new mechanism that governs how signals are transmitted across the cardiac cell membrane.