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Biomedical subjects

A Petit

Publications and source records attributed to A Petit.

212 records · Page 12Linked to original sources
PubMedDate not supplied

Phosphorylcholine antigens from Nippostrongylus brasiliensis. I.--Anti-phosphorylcholine antibodies in infected rats and location of phosphorylcholine antigens.

The anti-phosphorylcholine (PC) antibody synthesis was investigated in the rat after infection with the nematode Nippostrongylus brasiliensis. Serum IgM and IgG antibodies were demonstrated from day 2 or 3 post-infection. Intestinal IgA-antibody synthesis began shortly after the worms reached the intestine. Antigens containing PC were located with the fluorescent antibody technique in L3 infective larvae, adult worms and eggs of the parasites. They were always found to internal structures such as intestinal tract or gonads. It seems, therefore, that the anti-PC antibody synthesis resulted from the release of PC antigens by the parasite (moulting fluids, excretion, secretion or breakage products).

Animals↗
PubMedDate not supplied

Cytidine-5'-diphospho-choline conjugates. I.--Synthesis and fixation to phosphorylcholine-binding proteins.

The oxidation of the ribose ring of cytidine-5'-diphospho-choline (CDPC) by periodate to produce reactive dialdehydes was used to couple this activated reagent onto various proteins, onto Ficoll 400 and onto Sepharose 4B. Careful control of parameters of the different steps of the reaction enabled us to synthesize conjugates with a graded number of nucleotide residues. Human serum albumin conjugates with a relatively high degree of substitution were used to demonstrate and to measure anti-phosphorylcholine antibodies and the acute phase reactant, C-reactive protein by precipitation or passive haemagglutination techniques. These methods for measuring C-reactive protein in serum of patient suffering from acute inflammation may be useful for clinicians. CDPC-AH Sepharose was used to purify the phosphorylcholine-binding myeloma protein HOPC8 and to separate C-reactive protein from the bulk of serum proteins. Improvements of this technique will certainly lead to the complete purification of C-reactive protein.

Animals↗
PubMedDate not supplied

Cytidine-5'-diphospho-choline conjugates. II.--Immunogenicity in rats.

Cytidine diphospho-choline (CDPC) derivatives of human serum albumin (HSA) are immunogenic in the rat when injected in adjuvants. They induce a very rapid synthesis of IgM anti-phosphorylcholine antibodies which was followed by the synthesis of anti-CDPC antibodies and of anti-HSA antibodies. The activated nucleotide was able to induce specific skin sensitivity in rats after one skin painting. Gastric intubations of rats with low doses of HSA conjugates 8 days before an infection with the nematode Nippostrongylus brasiliensis were followed by a reduction of the resulting intestinal worm burden.

Animals↗
PubMedDate not supplied

[About eosinophilic infiltration in cellular tissue (author's transl)].

With this paper, we want to settle the part of eosinophilia in the definition of diseases as entities. Consequently, we emphasize the contribution of eosinophils in the histological diagnosis. Eosinophilic infiltration is the main marker of several lesions. We review successively some of these entities. They belong to tumoral or inflammatory (without or with vasculitis) pathology. The function of eosinophils must improve our knowledge about the significance of all these lesions (parasitic infestation, hypersensitivity...). These physiopathological mechanisms must be helpful to draw some new borders between these different entities.

Eosinophilia↗
PubMedDate not supplied

[Characteristics of intestinal immune response of rats infected with Nippostrongylus brasiliensis].

After infection of rats with Nippostrongylus brasiliensis the response was a synthesis of hemagglutinating antibodies in intestinal secretions, the activity of which is mainly due to IgA. When rats were infected with 83 larvae (which is the smallest immunizing dose), local antibodies were evidenced just after parasite localization had occurred in the gut, whereas serum antibodies were not detected before a challenge infection. Some of these local antibodies were directed against two types of worm antigen which can induce immunity: sevretory antigens and phosphorylcholine. These experiments a role for local antibodies in mechanism of worn expulsion.

Animals↗
PubMedDate not supplied

Effects of calcium concentration, lactobionate content, and sodium/ potassium ratio of preservation solutions on resting left ventricular pressure and postreperfusion function of rabbit heterotopic heart transplants.

BACKGROUND: We tested the hypothesis that the University of Wisconsin solution has a ionic composition (i.e., intracellular, calcium-free, lactobionate-enriched) that may be beneficial for cold heart graft preservation independently from any additives. METHODS: St. Thomas' Hospital and University of Wisconsin solutions were compared with the following: (1) C solution, a simplified University of Wisconsin-like solution (i.e., intracellular, calcium-free, lactobionate-enriched); (2) A solution, an St. Thomas' Hospital-like solution (extracellular, calcium [Ca2+] = 1.2 mmol/L) in which chloride was replaced by lactobionate; (3) B solution, an intracellular, lactobionate-enriched, calcium-containing solution ([Ca2+] = 1.2 mmol/L). Rabbit hearts were transplanted heterotopically in the abdomen of recipient animals either immediately or after 6 hours of storage. Hemodynamic parameters were recorded 60 minutes after unclamping. RESULTS: After a 6-hour storage, University of Wisconsin and C solutions provided better preservation than B and St. Thomas' Hospital solutions: diastolic pressures were lower; developed pressure and rate of pressure rise were higher. C solution was superior to University of Wisconsin solution only for rate of pressure rise. A solution was intermediary. A significant alteration of resting pressure and hemodynamic parameters was generally observed during the 6-hour storage. Nonsignificant changes of developed pressure and rate of pressure rise were only observed in C and B solutions: This is explained by systolic alteration after immediate reimplantation for the B group and good preservation for the C group. Resting pressure was unchanged over a 6-hour storage only for the C group, but this measure was not determined for University of Wisconsin. A correlation exists for various left ventricular volumes between resting pressure and postreperfusion hemodynamic data. Replacement of chloride by lactobionate (A versus St. Thomas' Hospital) may have improved resting and diastolic pressures by other mechanisms than limitation of net water gain during storage.

Adenosine↗
PubMedDate not supplied

Expression of angiotensin II type-I receptor and phospholipase C-linked G alpha q/11 protein in the human placenta.

OBJECTIVE: A recent study on the distribution of angiotensin II (ANG II), ANG II (AT) receptors, and human placental lactogen in human placental tissues from term pregnancies showed positive correlations among these indices, suggesting an important role for ANG II in placental endocrinology. However, nothing is known about the ontogenesis of this functional role for ANG II during pregnancy. Therefore, the aim of this study was to investigate the placental AT receptor expression at various trimesters of pregnancy. We also studied the ontogenesis of phospholipase C-linked G alpha q/11 protein, which is known to transduce ANG II type-1 (AT1) receptor signal. METHODS: Western blot analysis of placental membrane proteins was performed using a chemiluminescence kit and specific antibodies against AT1 receptor and G alpha q/11 protein. Northern blot analyses of AT1 receptor and G alpha q/11 mRNA expression were accomplished using random primed [32P]dCTP-labeled specific probes. RESULTS: The autoradiographs of AT1 receptor mRNAs (2.4 kb) and proteins (83 kDa) showed a progressive 4.8-fold and 2.6-fold increase, respectively, during pregnancy, with maximal levels at term. We also observed progressive 1.8-fold and 4.5-fold increases of G alpha q/11 protein (43 kDa) and mRNAs (4.5, 6.0, and 7.1 kb), respectively, during pregnancy, with maximal levels observed at term. CONCLUSION: Our results demonstrate that both the human placental AT1 receptor content and the G alpha q/11 protein level increase during pregnancy, and suggest that the AT1 receptor pathway may play a role in human placental physiology.

Animals↗
PubMedDate not supplied

Phosphorylcholine antigens from Nippostrongylus brasiliensis. II.--Isolation and partial characterization of phosphorylcholine antigens from adult worm.

The phosphorylcholine antigens (C substance) were specifically isolated from Nippostrongglus brasiliensis adult worms. They formed a gorup of fairly closely related molecules, but it was not possible to evidence that the carrier molecule was unique. An indirect immunoenzymatic test using immobilized lectins (concanavalin A, phytohaemagglutinin Els, wheat germ agglutinin, recin types I and II, peanut agglutinin) gave some light on the carbohydrate composition of the carrier molecules, whereas the amino acid part of these molecules seemed to indicate an unique oligopeptide, the composition of which would be: Asx (4), Thr (2), Ser (4), Glux (6), Gly (6) Ala (3), Val (2), Ile (1), Leu (2), Phe (8), Lys (2), Arg (1). An epitope of the carrier molecules was demonstrated with anti-N. brasiliensis egg antisera. It was shared with various pathogens including Haemonchus contortus, Schistosoma mansoni and Dipetalonema vitae. It was also found on the purified pneumococcal C. polysaccharide. The C. substance from a variety of parasites can now be isolated by a combination of specific reactions using both anti-phosphorylcholine and anti-carrier molecule antibodies.

Amino Acids↗