Biomedical subjects

L Barbot

Publications and source records attributed to L Barbot.

13 recordsLinked to original sources

PubMed2004

[Element of digestive pathophysiology and fecal analysis].

Fecal analysis includes qualitative and quantitative studies which allows quantification and labelling of numerous pathophysiologic phenomenona. Malabsorption and over-absorption of water and electrolytes give rise to six types of watery diarrheas, and two types of constipations; malabsorption of nutriments and maldigestion of food, give rise to two types of fatty and nitrogenous diarrheas with metabolic consequences. Fecal analysis often discriminates organic from non-organic diseases and brings informations on increase or decrease of caloric losses, to the nutritionist. Microscopic observations which requires a high degree of competence and experience, allows the recognition of malabsorption/maldigestion phenomenona, of fortuitous presence of parasites and a good interpretation of a fecal file.

Digestive System Diseases↗

PubMed2004

[New fecal markers: recent developments and perspectives].

Fecal occult blood testing is the most widely prescribed screening test for colorectal cancer. Recent development of immunological tests has increased specificity. Fecal DNA analysis opens up a new field for early detection of this widespread neoplasia. Inflammatory bowel disease is another important area where the development of fecal markers provides an interesting alternative to the gold standard but costly and invasive endoscopic investigations with histological analysis of biopsy specimens. Fecal TNFalpha and calprotectin can now be proposed to distinguish organic from non-organic intestinal disease, so select candidates for further investigations, and to assess disease activity. Measurement of fecal elastase provides real progress in screening for exocrine pancreatic insufficiency in patients with malabsorption syndrome. The development of non-invasive fecal markers is thus of increasing interest, providing data about the entire gastrointestinal tract useful for screening and individual patient management.

Animals↗

PubMed2004

[Quality control in coprology].

Quality control in medical laboratories was defined in guidelines for good execution of laboratory analyses issued by the French health authorities in 1994. Application of these guidelines is difficult in coprology because the sample is a complex heterogeneous matrix which varies with disease, surgery, food intake, and treatment. In addition, commercial quality control kits are not available for stool biochemical analyses and a national quality control program has not been established. We thus developed our own fecal quality control technique using pooling lyophylized stool samples. Manual or partially automated methods are used in coprology, leading to a long pre-analysis phase which is not always taken into account in quality control. This implies the need for complementary tools to insure the quality of coprology analyses. For example, semi-quantitative microscopic lipid analysis can be used as an internal standard for a given specimen. Quality assurance also involves a post-analytical phase where results obtained for a given specimen are compared with other available data and interpreted in light of the patient's clinical and therapeutic status. This quality assurance strategy enables accurate reliable results useful for long-term patient management.

Animals↗

PubMed2004

High faecal calprotectin concentrations in newborn infants.

BACKGROUND: Calprotectin, a major component of soluble cytosolic proteins in human neutrophil granulocytes, is excreted in excess in stools during inflammatory bowel disease in adults and children. Faecal calprotectin concentrations are also higher during the first year of life than in adults. OBJECTIVES: To measure faecal calprotectin concentrations in the neonatal period and define reference values according to the mode of feeding: standard infant formula, prebiotic infant formula (Calisma, Blédina SA, France), or breast feeding. PATIENTS AND METHODS: A prospective study was carried out over three months in 69 full term, healthy newborns with a median gestational age of 39.8 weeks (range 37-41.5) and a birth weight of 3300 g (range 2600-4460). Three groups were formed depending on the mode of feeding: group 1 (n = 18) received a standard infant formula, group 2 (n = 19) the prebiotic infant formula, and group 3 (n = 32) was breast fed. One stool sample was taken from each newborn on day 4 (3-7), and faecal calprotectin analysed using a commercial enzyme linked immunoassay (Calprest, Eurospital, Italy). RESULTS: Faecal calprotectin concentrations (median 167 micro g/g) were higher than reference values in healthy adults. The concentration was below the upper reference limit for adults (50 micro g/g) for three infants only, one fed the standard formula and two fed the prebiotic formula. Concentrations did not differ significantly according to method of feeding. CONCLUSIONS: Compared with healthy adults, newborns have high calprotectin concentrations in the first days of life. There is no obvious influence of the mode of feeding.

Breast Feeding↗

PubMed2003

Evidence for the absence of an intestinal adaptive mechanism to compensate for C. parvum-induced amino acid malabsorption in suckling rats.

In order to assess the impact of Cryptosporidium parvum on host intestinal physiology, we investigated absorption of the two principal amino acids in dam's milk (leucine, glutamate), using Ussing chambers and RT-PCR analyses. Experiments were performed in both heavily (ileum) and mildly (duodenum) infected segments of the small intestine at the peak of infection [day 8 post-infection (PI)] and after spontaneous clearance of the parasite (day 17 PI). At day 8 PI, amino acid fluxes across the mucosa were decreased throughout the small intestine (P<0.01) and EAAT3 mRNA expression was reduced ( from -49% to -28%). At day 17 PI, leucine and glutamate fluxes were normalized but the decrease in EAAT3 mRNA levels persisted (from -31% to -46%). Our results demonstrate that cryptosporidiosis induces major amino acid malabsorption involving the entire small intestine which is not counterbalanced by any up-regulation, even after spontaneous clearance of the parasite.

Amino Acid Transport System X-AG↗

PubMed2002

Intestinal peptide transporter PepT1 is over-expressed during acute cryptosporidiosis in suckling rats as a result of both malnutrition and experimental parasite infection.

Cryptosporidium parvuminfection induces amino acid malnutrition leading to growth retardation in children. Owing to the nutritional efficiency of peptides compared to free amino acids and the resistance of the di-tripeptide transporter PepT1 to mucosal injury, we analyzed the intestinal expression of PepT1 during experimental acute cryptosporidiosis in suckling rats from day 4 to day 50. PepT1 mRNA levels were increased at the peak of infection (day 10) all along the small intestine and normalized after spontaneous clearance of the parasite (day 21). Immunolocalization of PepT1 showed that its expression was maintained in the brush border membrane of enterocytes in infected rats from day 4 to day 50 all along the small intestine. Our results suggest a transcriptional up-regulation during acute cryptosporidiosis in response to both C. parvum-induced malnutrition and parasite implantation. As no treatment is available, a semi-elemental diet should be considered part of the treatment of cryptosporidiosis.

Acute Disease↗

PubMed2002

Low levels of pancreatic elastase 1 in stools of preterm infants.

The amount of faecal pancreatic enzyme elastase 1 was significantly lower in 42 preterm newborns than in 12 full term babies at day 2 (89 (3-539) v 354 (52-600) microg/g, p<0.0007) and day 5 (164 (3-600) v 600 (158-600) microg/g, p<0.05) and correlated positively with total nutrient intake during the first week of life in preterm infants. This should probably be taken into account during early feeding.

Feces↗

PubMed2001

Impairment of amino-acid absorption in suckling rats infected with Cryptosporidium parvum.

In the present study. we explored the nutritional consequences of cryptosporidiosis. In order to ascertain the direct responsibility of C. parvum for impairment of staturoponderal development observed during the infection in neonatal animals, we investigated the absorption of two major components of the total amino acids in dam's milk (leucine and glutamate) across the ileal mucosa. The infection resulted in significant (47% and 34%, respectively) reductions in leucine and glutamate fluxes (P<0.01). Moreover, the leucine aminopeptidase and alkaline phosphatase activities were reduced in the infected ileal mucosa. Interestingly, the reduction in weight gain, which began at day 6 post-infection (PI), persisted until day 20 PI, although no cryptosporidia were detected in the ileal mucosa after day 12 PI. We thus provide evidence that the malabsorption of amino acids during cryptosporidiosis contributes to impairing the development of neonatal animals, with consequences that persist beyond eradication of the parasite.

Alkaline Phosphatase↗

PubMed2001

[Cryptosporidium parvum: functional study of the intestinal malabsorption syndrome].

Cryptosporidiosis is an important cause of diarrhea associated with growth retardation in children and severe malnutrition in immunocompromised patients. The pathophysiology is poorly understood. In the suckling rat model, we show that C. parvum infection impairs net electrogenic transport across the ileal mucosa without involvement of prostaglandins, as well as trans- and paracellular permeability and leucine and glutamate absorption. These results provide evidence for the development of an intestinal malabsorptive syndrome during cryptosporidiosis. Unspecific process such as villous atrophy and inflammatory cytokines secretion should be regarded as possible mediators of this syndrome. However, specific mechanisms have to be considered since C. parvum induces a rearrangement of the host enterocyte cytoskeleton which might impaired intracellular trafficking thus reducing the membrane expression of nutrient transporters. Infection and malnutrition are known to be tightly associated, making each other worse. As no specific efficient therapy exists, cryptosporidiosis-induced malnutrition must be taken into account when establishing therapeutic scheme.

Animals↗

PubMed2000

SR142801 behaves as a tachykinin NK-3 receptor agonist on a spinal nociceptive reflex in the rat.

Effects of two commonly used tachykinin NK-3 receptor antagonists (SR 142801 and R820) intrathecally (i.t.) administered were assessed in the rat tail-flick test. SR142801 and its (R)-enantiomer SR142806 (1.3, 6.5 and 65 nmol) were found as potent as senktide and [MePhe7]NKB (NK-3 selective agonists) to induce transient antinociceptive effects. Naloxone (10 microg) and R820 (6.5 nmol) blocked reversibly the responses to 6.5 nmol senktide, [MePhe7]NKB, SR142801 and SR142806 when administered i.t. 15 min earlier. However, the antinociceptive responses induced by SR142801 and SR142806 were not affected by i.t. pretreatments with NK-1 (6.5 nmol SR140333) and NK-2 (6.5 nmol SR48968) receptor antagonists. In control experiments, the NK-1 and NK-2 antagonists prevented the hyperalgesic effects to NK-1 ([Sar9,Met(O2)11]SP) and NK-2 ([beta-Ala8] NKA(4-10)) receptor agonists (6.5 nmol i.t.), respectively. R820 had no direct effect on nociceptive threshold and failed to alter angiotensin II-induced antinociception. The data suggest that the antinociceptive effect of SR142801 is due to an agonist effect at NK-3 receptor in the rat spinal cord that involves a local opioid mechanism. These results can be best explained by the existence of inter-species NK-3 receptor subtypes.

Analgesics↗

PubMed1999

Characterization of central and peripheral effects of septide with the use of five tachykinin NK1 receptor antagonists in the rat.

1. Effects of two tachykinin NK1 receptor selective agonists (septide and [Sar9, Met(O2)11]SP) were compared on the increases in mean arterial pressure (MAP), heart rate (HR) and motor behaviour following intracerebroventricular (i.c.v.) administration in unanaesthetized rat, and on the vascular permeability increases to intradermal (i.d.) injection in the anaesthetized rat. Moreover, five tachykinin NK1 receptor selective antagonists (LY303870, LY306740, LY303241, SR140333 and RP67580) were tested against the two agonists to compare their pharmacological profile. 2. [Sar9, Met(O2)11]SP and septide (10-100 pmol per rat, i.c.v.) were equipotent in increasing MAP and HR, yet they had dissimilar time-course. Both agonists increased dose-dependently face washing and sniffing while [Sar9, Met(O2)11]SP was the sole to produce grooming, septide was more potent than [Sar9, Met(O2)11]SP (6.5-650 pmol) in increasing vascular permeability. 3. For most centrally mediated responses, LY303870 and RP67580 were significantly more potent in inhibiting septide than [Sar9, Met(O2)11]SP. In some parameters, greater blockade was achieved when antagonists (particularly LY306740) were given 1 h instead of 10 min prior to i.c.v. septide. 4. All antagonists except LY303241 blocked dose-dependently the increases in vascular permeability to equipotent doses of [Sar9, Met(O2)11]SP and septide. LY303870 and LY306740 were more potent against septide. 5. The antagonism afforded by LY303870, LY306740 and LY303241 was stereoselective and only SR140333 was found to cause central and peripheral non specific effects. 6. The data confirm a distinct pharmacological profile for septide in vivo. RP67580 and LY306740 are currently the most valuable tachykinin NK1 receptor antagonists for in vivo studies in rat.

Acetamides↗

PubMed1998

Functional specialization of stable and dynamic microtubules in protein traffic in WIF-B cells.

We found that the magnesium salt of ilimaquinone, named 201-F, specifically disassembled dynamically unstable microtubules in fibroblasts and various epithelial cell lines. Unlike classical tubulin- interacting drugs such as nocodazole or colchicine which affect all classes of microtubules, 201-F did not depolymerize stable microtubules. In WIF-B-polarized hepatic cells, 201-F disrupted the Golgi complex and inhibited albumin and alpha1-antitrypsin secretion to the same extent as nocodazole. By contrast, 201-F did not impair the transport of membrane proteins to the basolateral surface, which was only affected by the total disassembly of cellular microtubules. Transcytosis of two apical membrane proteins-the alkaline phosphodiesterase B10 and dipeptidyl peptidase IV-was affected to the same extent by 201-F and nocodazole. Taken together, these results indicate that only dynamically unstable microtubules are involved in the transport of secretory proteins to the plasma membrane, and in the transcytosis of membrane proteins to the apical surface. By contrast, stable microtubules, which are not functionally affected by 201-F treatment, are involved in the transport of membrane proteins to the basolateral surface. By specifically disassembling highly dynamic microtubules, 201-F is an invaluable tool with which to study the functional specialization of stable and dynamic microtubules in living cells.

Albumins↗

PubMed1997

Cardiovascular and behavioural effects of intracerebroventricularly administered tachykinin NK3 receptor antagonists in the conscious rat.

1. In the conscious rat, three tachykinin NK3 receptor antagonists, namely SR142801 ((S)-(N)-(1-(3-(1-benzoyl-3-(3,4-dichlorophenyl)piperidin-3-yl)pro pyl)-4-phenylpiperidin-4-yl)-N-methylacetamide), R820 (3-indolylcarbonyl-Hyp-Phg-N(Me)-Bzl) and R486 (H-Asp-Ser-Phe-Trp-beta-Ala-Leu-Met-NH2) were assessed against the intracerebroventricular (i.c.v.) effects induced by senktide, a selective NK3 receptor agonist, on mean arterial blood pressure (MAP), heart rate (HR) and motor behaviour. 2. Senktide (10-650 pmol per animal; i.c.v; n = 4-16) at the lowest dose caused a significant fall in MAP (-10 +/- 6 mmHg), while at the highest doses (100 and 650 pmol), senktide caused a rise in MAP (9 +/- 3 and 12 +/- 1 mmHg, respectively) when compared to vehicle. The intermediate doses (25 and 65 pmol) had no effect on MAP. The highest two doses caused a tachycardia of 62 +/- 15 and 88 +/- 8 beats min(-1), respectively. The dose of 65 pmol had a biphasic effect on HR, an initial bradycardia of 47 +/- 12 beats min(-1) followed by a tachycardia of 46 +/- 14 beats min(-1). The lowest doses caused either a rise of 52 +/- 10 beats min(-1) (25 pmol) or no effect (10 pmol) on HR. All doses of senktide caused similar increases in face washing, sniffing and wet dog shakes except at the dose of 100 pmol, when wet dog shakes were more than double those observed with the other doses. 3. The antagonist SR142801 (100 pmol -65 nmol per animal; i.c.v.; n = 6-8) caused increases in MAP at the highest two doses (6.5 and 65 nmol) while HR, dose-dependently, increased (23 +/- 6 to 118 +/- 26 beats min[-1]) and the onset dose-dependently decreased. The (R)-enantiomer, SR142806 (100 pmol - 65 nmol per animal; i.c.v.; n = 6-8) only caused rises in MAP (13 +/- 2 mmHg) and HR (69 +/- 11 beats min[-1]) at the highest dose. These drugs had no apparent effect on behaviour, except for the highest dose of SR142801 which increased sniffing. The antagonist R820 (650 pmol - 6.5 nmol per animal; i.c.v.; n = 6) had no effect on MAP or HR and only increased sniffing behaviour at 6.5 nmol. At 650 pmol (n = 6), R486 had no effect on any variable, but at 3.25 nmol, i.c.v. (n = 4) a delayed tachycardia and a significant increase in all behavioural variables were observed. 4. The cardiovascular responses induced by 6.5 nmol SR142801 and 25 pmol senktide were inhibited by R820 (6.5 nmol, 5 min earlier i.c.v.). In contrast, R820 failed to affect the central cardiovascular and behavioural responses induced by 10 pmol [Sar9, Met(O2)11]substance P, a NK1 receptor selective agonist. The senktide-induced behavioural changes were not inhibited by R820 (6.5 nmol, i.c.v.) while R486 (650 pmol, i.c.v.) blocked both the cardiovascular and behavioural responses to 25 pmol senktide. A mixture of antagonists for NK1 (RP67580; 6.5 nmol) and NK2 (SR48968; 6.5 nmol) receptors injected i.c.v. did not affect the cardiovascular response to SR142801. Cross-desensitization was shown between the central responses to SR142801 and senktide, but not between SR142801 and [Sar9, Met(O2)11]substance P. 5. The antagonists SR142801 and SR142806 (6.5-650 nmol kg(-1); n = 5-7), given i.v., did not evoke any cardiovascular or behavioural changes, except a delayed bradycardia for SR142806 (650 nmol kg[-1]), and also failed to inhibit the increase in MAP evoked by senktide (4 nmol kg(-1), i.v.). However, at the highest dose, both drugs slightly reduced the senktide-induced tachycardia. 6. Although the present data are consistent with the in vitro pharmacological bioassays and binding data, showing that SR142801 is a poor antagonist at rat peripheral NK3 receptors, they suggest that SR142801 has a partial agonist action at these receptors centrally. A separation of the cardiovascular and behavioural effects mediated by central NK3 receptor activation was achieved with SR142801 and R820 but not with R486. These results could be explained by the existence of NK3 receptor subtypes in the rat or by the differential activation and inhibition of the same receptor protein linked to the production of different second messengers. Differences in the pharmacokinetic or pharmacodynamic properties of the antagonists cannot be excluded at this time.

Animals↗