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Biomedical subjects

F Leclercq

Publications and source records attributed to F Leclercq.

81 records · Page 5Linked to original sources
PubMed1982

Caiman crocodylus hemoglobin. Complete primary structures of alpha and beta chains; phylogenic and regulatory aspects.

In some reptiles, the hemoglobin oxygen affinity is lowered by CO2 and not by the usual phosphate cofactors. To understand the molecular mechanism of this regulation, Caiman crocodylus hemoglobin's primary structure has been determined. The alignment of the 141 residues of the alpha chain as well as the 146 of the beta chain were obtained by classical method of sequence analysis and are compared with some mammalian, avian, amphibian, and fish hemoglobin chains. Furthermore, from these sequences, it is possible to explain the non-interaction of phosphorylated cofactors with the caiman deoxyhemoglobin on the basis of mutations of the amino acids responsible for their fixation on the beta chain. Among these residues only lysine beta 82 is unchanged. In addition a site has been proposed for the fixation of HCO3- which involves ionic bonds with serine beta 1 and glutamic acid beta 144 (Perutz et al. (1981) Nature 291, 682-684) (1).

Alligators and Crocodiles↗
PubMedDate not supplied

Evaluation of frog gastric mucous secretion by 7T magnetic resonance imaging.

This work describes a new method to evaluate the action of drugs on gastric mucus secretion by 7 T MRI. A polyethylene probe was inserted into the stomach of frogs, a water washing cycle was performed, air was inflated into the stomach, and the probe was removed. Drugs were administered topically by mixing them with the water used for stomach washing, and a series of images was collected. In untreated animals, a mucous layer emitting a high intensity signal covered the gastric mucosa. Atropine administration strongly reduced the mucous layer thickness. After pilocarpine administration, MRI images showed that the mucous layer was thicker than in controls. After metacholine administration, the thickness of the mucous layer was increased in comparison with both controls and pilocarpine-treated animals, in accord with the expected drug-induced increase of mucous secretion. Quantitative analysis of the mucous layer thickness on MRI images confirmed the above findings. In conclusion, these results indicate that MRI at 7 T is a sensitive in vivo screening test to evaluate the effect of drugs on gastric mucus secretion in absence of surgical manipulation, thereby enabling morphofunctional studies that cannot be performed by conventional methods.

Animals↗
PubMedDate not supplied

Cardiac troponin I in patients with hematologic malignancies.

BACKGROUND: The cardiac isoform of troponin I (cTnI) is a myofibrillar protein highly specific for myocardial injury. We used a recently developed new-generation immunoassay with high analytical sensitivity to measure cTnI in patients diagnosed with hematologic malignancies, before chemotherapy and after an intermediate cumulative dose of anthracyclines. We hypothesized that measurement of cTnI with this sensitive method would provide evidence of myocardial injury in these patients. METHODS: Sera from 115 individuals (60 healthy controls, 25 anthracycline-naive patients and 30 patients treated with intermediate cumulative doses of anthracyclines) were assessed for cTnI, creatine kinase MB (CKMB) mass and myoglobin. Radionuclide left ventricular ejection fraction (LVEF) was also determined. RESULTS: Using this sensitive assay, detectable concentrations of cTnl were measured in the healthy population [mean, 19.5 pg/ml, 95% confidence interval (CI) 13.5-25.5 pg/ml]. Anthracycline-naive patients had cTnI mean values (36.5 pg/ml, 95% CI 25.1-47.9 pg/ml) that were significantly (P < 0.01) greater than those in the control group. cTnI was significantly (P < 0.00001) increased in anthracycline-treated patients (76.4 pg/ml, 95% CI 67.0-85.8 pg/ml) compared with both the anthracycline-naive patients and the controls. CKMB, myoglobin and LVEF were within the normal range in all patients. CONCLUSIONS: These data provide evidence for cardiac involvement in patients with hematological malignancies before and during the course of anthracycline chemotherapy. They suggest that detection of myocardial injury may be facilitated by measurement of cTnI with a highly sensitive assay.

Adult↗