Biomedical subjects

C Malbert

Publications and source records attributed to C Malbert.

9 recordsLinked to original sources

PubMed2003

Development and biodistribution of 188Re-SSS lipiodol following injection into the hepatic artery of healthy pigs.

Although intra-arterial radiotherapy with (131)I-labelled lipiodol is a useful therapeutic approach in the treatment of hepatocellular carcinomas, various disadvantages limit its use. Here we describe the development of (188)Re-SSS lipiodol, as well as its biodistribution in the healthy pig after injection into the hepatic artery. The (188)Re-SSS lipiodol was obtained after dissolving a chelating agent, previously labelled with (188)Re, in cold lipiodol. The radiochemical purity (RCP) of the labelling was checked immediately and at 24 and 48 h. The (188)Re-SSS lipiodol was injected into the hepatic artery of six healthy pigs. They were killed 1, 24 and 48 h post injection, for ex vivo counting. An autoradiographic study was performed in three cases. (188)Re-SSS lipiodol was obtained with a yield of 87%+/-9.1%. The immediate RCP was 93%+/-3.4%. This radiolabelling was reproducible and stable at 48 h in plasma: 90.6%+/-1.5% of the activity remained in the lipiodol with an RCP of 91%+/-4%. Ex vivo counting confirmed the predominantly hepatic uptake and revealed weak lung and intestinal uptake. There was very weak urinary elimination (2.3%+/-0.5% at 48 h) and a slightly higher level of intestinal elimination (4.8%+/-1.9% at 48 h). The autoradiographic studies showed (188)Re-SSS lipiodol to be located mainly in sinusoids, like (131)I-lipiodol. By using the method described here, (188)Re-SSS lipiodol can be obtained with a very high yield and a satisfactory RCP. Its biodistribution in the healthy pig is in agreement with data published elsewhere concerning other types of radiolabelling used for lipiodol, except for the very weak urinary and intestinal elimination, which probably indicates better stability of (188)Re-SSS labelling.

Animals↗

PubMed1996

Intraluminal micromanometry: an evaluation of the dynamic performance of micro-extrusions and sleeve sensors.

Conventional manometric techniques are unsuitable for studies in premature infants and small laboratory animals. We have therefore developed silicone rubber 5-lumen and 10-lumen micromanometric extrusions with an o.d. 2.0 mm and lumina of 0.35 mm i.d. This study evaluates the suitability of microextrusions for intraluminal perfusion manometry. Pressure offset, post-occlusion pressure rise rate and sphincter model studies were used to assess the manometric performance of the extrusions and a miniature sleeve sensor (25 mm long) at infusion rates of 0.01-0.1 mL min-1. Micro-extrusions (5-lumen/10-lumen, respectively) had offsets (per 100 cm of length) of 3.8/5.0 mmHg at 0.01 mL min-1 and 25.6/26.2 mmHg at 0.1 mL min-1 and rise rates (in 160 cm lengths) of 64/43 mmHg sec-1 at 0.01 mL min-1 and 330/224 mmHg sec-1 at 0.1 mL min-1. Infusion rates 0.025 mL min-1 produced rise rates 100 mmHg sec-1. The miniature sleeve sensor had minimal resistance to perfusion, rise rates of 3 mmHg sec-1 at 0.01 mL min-1 and 23 mmHg sec-1 at 0.1 mL min-1 and recorded pressure as accurately as a side hole. We conclude that the performance of micromanometric extrusions and sleeves is sufficient for intraluminal perfusion manometry.

Animals↗

PubMed1995

Mechanics of pulsatile transpyloric flow in the pig.

1. In eight conscious pigs equipped with gastric and duodenal cannulae, the relationship of transpyloric flow to gastro-duodenal motor events was evaluated during gastric emptying of 1000 ml of saline. Rates of liquid gastric emptying were correlated with pressures at the antrum, pylorus and duodenum, recorded by a sleeve sensor and multiple perfused side-holes. Transpyloric flow was recorded concurrently by continuous collection and weighing of the duodenal effluent. 2. In three pigs the above measurements were repeated during concurrent videofluoroscopy of gastric emptying after adding 100 ml of liquid barium to the gastric instillate. 3. The mean volume of saline emptied in 30 min was 627 +/- 51.2 ml. Pulsatile flow accounted for 71% of total emptying. Pulses had a mean flow rate of 3.9 +/- 0.44 ml s-1. Most flow pulses (59%) occurred during the first 5 min of emptying. 4. Distinctive, low-amplitude (4.8 +/- 0.33 mmHg), relatively long-lasting (15.8 +/- 0.46 s) antral pressure waves were associated with 58% of flow pulses. In all antral pressure recording points, the first and longest duration component of these pressure waves had an identical timing, amplitude and waveform consistent with pressurization of the entire antrum-gastric cavity. 5. Videofluoroscopy and concurrent manometry showed that these antral common cavity pressure waves were associated with non-lumen-occlusive contractions of the gastric wall, initially observed at the corpus which propagated down to the pylorus; 93% of these contractions became lumen occlusive in the terminal antrum and pylorus when pressure waves of a unique pattern for each recording point were recorded at this level. 6. The onset of 68% of the flow pulses which accounted for 62% of pulsatile emptying occurred in the interval (mean 7.9 +/- 0.65 s) between the onset of the common cavity wave and the onset of localized, lumen-occlusive distal antral-pyloric pressure waves. 7. These findings indicate that in the pig, pulsatile emptying of non-nutrient liquids into the duodenum occurs predominantly during the non-lumen-occlusive stage of a propagated gastric contraction, which is recognisable as a common cavity pressure wave. This is a previously inadequately recognized pattern of gastric pumping.

Animals↗

PubMed1995

Effect of drink temperature on antropyloroduodenal motility and gastric electrical activity in humans.

There is little information on the motor mechanisms underlying the effects of meal temperature on gastric emptying. The effects on antropyloric pressures and the surface electrogastrogram of ingesting drinks at 4 degrees C, 37 degrees C, and 50 degrees C (350 ml normal saline and 50 ml low calorie (7 kj) orange cordial) given in randomised order were measured over 60 minutes in 12 normal volunteers (10 men and 2 women, aged 18-55 years). The warm and cold drinks suppressed antral pressure waves (p < 0.05), altered the organisation of antropyloric pressure waves (p < 0.05), stimulated isolated pyloric pressure waves (p < 0.05), and increased electrogastrogram frequency (p < 0.05) when compared with the 37 degrees C drink. These changes were greatest in the first 30 minutes after ingestion and greater (p < 0.05) with the 4 degrees C drink. Temperature has major effects on postprandial antropyloroduodenal motility in normal subjects. Both cold and warm drinks stimulate a pattern of motility associated with retardation of transpyloric flow.

Adolescent↗

PubMed1995

Relationship between surface electrogastrography and antropyloric pressures.

The cutaneous electrogastrogram (EGG) and intraluminal antropyloroduodenal pressures were recorded in 12 healthy volunteers for 30-min periods during phase II of the interdigestive motor complex, during intraduodenal infusion of 10% triglyceride, and after intravenous erythromycin (3 mg/kg). During phase II, the frequency of the EGG was relatively constant in each individual, with a median frequency of 0.046 Hz [2.8 counts per minute (cpm)]. EGG frequency was greater (P < 0.05) than the median rate of antral pressure waves (1.8 cpm). The suppression of antral pressure waves (P < 0.05) and stimulation of isolated pyloric pressure waves (IPPWs) (P < 0.05) produced by triglyceride infusion were not associated with changes in EGG frequency compared with phase II. The frequency of the EGG and the rate of IPPWs were comparable. After erythromycin, EGG frequency was 0.03 Hz (1.8 cpm), less than during both phase II and triglyceride infusion (P < 0.05) and almost identical to the rate of antral pressure waves. Pressure waves were nearly always associated with an EGG signal. In contrast, the temporal relationship between the EGG signal and pressure waves was variable. During triglyceride infusion (r = 0.83, P < 0.001) and after erythromycin (r = 0.83, P < 0.001) there was a close (approximately 1:1) relationship between the rate of pressure waves and EGG frequency. However, there was no significant relationship (r = 0.32, not significant) between the number of pressure waves and EGG frequency frequency during pase II.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1994

Effects of duodenal distention on fasting and postprandial antropyloroduodenal motility in humans.

BACKGROUND/AIMS: Mechanoreceptors in the proximal small intestine may play an important role in the regulation of gastric emptying. Balloon distention of the duodenum causes fundic relaxation. The purpose of the present study was to determine the effect of stimulation of duodenal mechanoreceptors on both fasting and postprandial antropyloroduodenal motility in humans. METHODS: Antropyloroduodenal pressures were recorded in 12 healthy volunteers with a sleeve-sidehole assembly, incorporating two balloons 5 and 20 cm distal to the pylorus. Duplicate proximal and distal duodenal balloon distensions with 10, 20, and 30 mL of air for 2.5 minutes were performed separately and in randomized order both during fasting and after a meal. RESULTS: During fasting, proximal and distal distention at all volumes increased the number of isolated pyloric pressure waves (P < 0.05) and basal pyloric pressure (P < 0.05), and the response to proximal distention was greater (P < 0.05). Postprandially, proximal and distal distention increased basal pyloric pressure (P < 0.05) with a greater response to proximal distention (P < 0.05), but had no effect on isolated pyloric pressure waves. Both during fasting and postprandially, there were more synchronous and less antegrade antral waves during distention (P < 0.05). The number of duodenal pressure waves increased during proximal (P < 0.05) but not distal distention. CONCLUSIONS: Stimulation of duodenal mechanoreceptors by balloon distention has significant and region-dependent effects on antropyloroduodenal motility that vary between fasting and postprandial states.

Adult↗

PubMed1986

Indirect stimulation by thyrotropin-releasing hormone of canine gallbladder motility.

Thyrotropin-releasing hormone (TRH) was unable to induce any noticeable contraction of canine isolated gallbladder strips up to the dose of 10(-4) g/ml, while caerulein (CAER) was spasmogenic in a dose-related manner beyond 10(-11) g/ml. This effect of CAER was unaffected by either atropine or tetrodotoxin. In conscious dogs, the intravenous bolus of TRH (20 micrograms/kg) or CAER (0.2-2.0 micrograms/kg) caused gallbladder emptying. The TRH response, unlike that of an equipotent dose of CAER, was prevented by atropine. In experiments on electrical activity of the digestive tract in conscious dogs, both TRH or CAER induced a concomitant increase on the myoelectrical activity in the proximal part of the small intestine. The excitatory effects were prevented by atropine only in the case of TRH. These results demonstrate that TRH stimulates indirectly the gallbladder and proximal duodenum of the dog. They suggest the involvement of a cholinergic pathway in this excitatory action.

Action Potentials↗

PubMed1985

[Control of antroduodenal motility in sheep].

The continuous but cyclic delivery of contents through the pylorus in the adult ruminant is regulated by the initiation of the migrating myoelectric complexes on the duodenal bulb. The motor responses of the pyloric antrum to the volume of digestive contents, the presence of lipids and ulcerogenic agents revealed that the inhibition of the motor antral activity, whatever its origin, resulted in a higher frequency of the duodenal cyclic motor events. Conversely, stimulation of duodenal motor activity, for example the increased frequency of migrating myoelectric complexes, resulted in the inhibition of the antral motor activity. It is suggested that the motor profile of the antroduodenal junction corresponded to interactions which fulfill the regulation of gastric emptying motor functions, with the first part of the duodenum as an extremely sensitive and rapid controlling mechanism.

Animals↗

PubMedDate not supplied

Antral compensation after proximal gastric vagotomy.

Proximal gastric vagotomy (PGV) has little impact on the normal pattern of solid gastric emptying, despite denervation of the proximal two thirds of the stomach and loss of the proximal gastric pump. In four healthy volunteers and four patients with PGV, we investigated the possible compensatory mechanisms that may come into play after proximal denervation of the stomach. We measured antropyloroduodenal motility with a 10-lumen sleeve/side-hole catheter for 180 minutes after ingestion of a dual-isotope radiolabeled mixed liquid/solid meal. Patients with PGV exhibited faster liquid emptying, but the rate of solid emptying was similar to that in healthy volunteers. The frequency of propagated antropyloric pressure wave was similar between the two groups, but patients with PGV exhibited less isolated pressure waves in the proximal antrum. The amplitude and duration of pressure waves recorded in the distal antrum were significantly increased in the PGV patients as compared to healthy volunteers. Although the pattern of propagated antral contractions and solid gastric emptying remains unchanged after PGV, there is an increase in the amplitude and duration of distal antral contractions, which may compensate for loss of proximal gastric pumping mechanisms.

Adult↗