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Biomedical subjects

J M Wal

Publications and source records attributed to J M Wal.

At least 55 records · Page 3Linked to original sources
PubMed1994

Essential fatty acid deficiency in the pig: effects on eicosanoid basal levels and in vitro synthesis by the small intestine.

The influence of nutritional essential fatty acid (EFA) deficiency on arachidonate metabolism by porcine small intestine has been studied. Great care was exercised in the manipulation of the jejunal wall to avoid artefactual metabolism of arachidonate. Thus, jejunal wall was frozen in liquid nitrogen after organ removal and washing, and subsequently lyophilized. This lyophilized tissue was used as starting material for all experiments, including organic solvent extractions (for basal level determinations) and reconstitution in aqueous buffer (for neosynthesis experiments). Feeding pigs with a low linoleate diet for 12 weeks resulted in a 36% diminution in the % of arachidonate in jejunal phospholipids. Basal levels of 6-keto prostaglandin F1 alpha (6-keto PGF1 alpha), thromboxane B2 (TXB2), PGF2 alpha, PGE2, PGD2 and leukotriene B4 (LTB4) were not altered in the EFA-deficient state. However, we observed a significant lowering of the synthesis of each of these eicosanoids (except LTB4) by the EFA-deficient jejunum during brief (15s) in vitro neosynthesis experiments. The origin of arachidonate as a substrate of PG endoperoxide synthase, also named PGH synthase or cyclooxygenase (Cox) in these neosynthesis experiments is probably a non-esterified fatty acid pool since, (1) neosynthesis was not inhibited by the phospholipase A2 (PLA2) inhibitor parabromophenacylbromide, and (2) substantial amounts of arachidonic acid were found in the jejunum, frozen or lyophilized. Cox activity of the lyophilized jejunum and Cox content of liver and intestine microsomes were not modified in the EFA-deficient state.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Tandem immunoaffinity and reversed-phase high-performance liquid chromatography for the identification of the specific binding sites of a hapten on a proteic carrier.

Immunoaffinity (IA) and reversed-phase (RP) high-performance liquid chromatography were combined for the identification of the specific binding sites of benzylpenicilloyl (BPO) groups on human serum albumin (HSA). Tryptic hydrolysates of BPO-HSA were loaded on the IA column. BPO-peptides were desorbed and concentrated directly on the RP column, coupled via a switching valve, then separated by using gradient elution and identified by the amino acid sequences. This single-step procedure permitted more than 95% recovery of the BPO-peptides present in minute amounts, with good specificity.

Amino Acid Sequence↗
PubMed1991

Enzyme immunoassay of benzyl penicilloyl (BPO) groups using acetylcholinesterase as label. Application to the study of the BPO-binding sites on albumin.

Benzyl penicilloyl groups (BPO) derive from penicillin G by cleavage of the beta lactam ring; they covalently bind to proteins to give conjugates which have lost all antibiotic properties but are considered as the major allergenic determinants in penicillin allergy. A solid-phase Enzyme Immuno Assay (EIA) of BPO groups in different biological fluids is described. It is a competitive immunoassay using acetylcholinesterase as label. In all biological fluids, very low non-specific binding values are observed. The sensitivity and the precision of the assay are good since ca. 0.5 ng/ml can be measured with a coefficient of variation less than 10%. Cross reactions between BPO and penicillin or penicillin derivatives are nil or very low. This assay is more sensitive, much more rapid and easier to handle than the other methods available and is thus suitable for routine determinations. In association with reversed-phase high performance liquid chromatography this EIA has allowed an initial investigation of the location of BPO-binding sites on micro quantities of serum albumin (ca. 1 mg) from penicillin treated patients.

Acetylcholinesterase↗
PubMed1991

Bovine serum albumin immunization: a new risk of allergy during protocols for in vitro fertilization.

Three patients having undergone protocols for in vitro fertilization (IVF) showed an allergic reaction suggesting seric disease 6 to 10 days after follicle aspiration. The responsibility of bovine serum albumin, present in the follicle-rinsing fluid and in the medium used for embryo culture was suspected. An immunological study was carried out, using two groups for comparison. Group 1: 7 controls. Group 2: 11 women having undergone IVF protocols without incident. Anti-BSA antibodies were present in low quantities in one or two subclasses of IgG and IgA in Group 1, and in several subclasses at higher levels in nine of 11 subjects from Group 2. The IgG4 response predominated 7 times out of 9. The antibody content gradually fell after the IVF attempt. An immune response predominated in the IgG1 in two patients. Skin test for the two fluids and BSA were positive only in the three patients. These results show the frequency of immunization to BSA induced through the ovarian and peritoneal pathways. Seric disease corresponds to a rise in IgG1. The association of a IgE-dependent sensitization is suspected. The authors suggest the possibility of an interference of these immune processes with implantation and propose the elimination of heterologous proteins from fluids. They also suggest that LH-RH analogues facilitate immune responses.

Adolescent↗
PubMed1990

Identification of the binding sites of benzyl penicilloyl, the allergenic metabolite of penicillin, on the serum albumin molecule.

Tryptic digests of fragment A299-585 of penicilloylated serum albumin obtained from two penicillin-treated patients or prepared by in vitro conjugation, were analyzed by a tandem immunoaffinity reversed-phase HLPC. Determinations of benzyl penicilloyl groups (BPO) were performed on the different fractions. Three BPO containing peptides were identified by their amino acid sequence and the bound BPO were located on lysines 432, 541 and 545. Six major BPO binding sites were thus identified on the whole albumin molecule. All of them are lysine residues and correspond to a limited number of definite structures in which lysine and serine residues appear to be closely associated.

Amino Acid Sequence↗
PubMed1990

Histamine and mast cell distribution in the intestinal wall of the germ free and conventional rats. Influence of the mode of sterilization of the diet.

The influence of the mode of sterilization of the diet (gamma-irradiation vs. autoclaving) on the histamine and mast cells distribution in the intestinal mucosa, was studied in germ free (GF) and conventional (CV) rats. Interactions between the diet and the digestive microflora were observed. Histamine concentration and mast cells counts are higher in CV rats small intestine than in GF's. The differences are increased with the irradiated diet. At the opposite in the hindgut, these values are higher in GF than in CV rats, especially in the rats fed the steam sterilized diet. The variations in the wall histamine contents and in the mucosal mast cells counts due to the diet and/or the microflora do not appear to be always correlated.

Animals↗
PubMed1989

Binding of benzyl penicilloyl to human serum albumin. Evidence for a highly reactive region at the junction of domains 1 and 2 of the albumin molecule.

Tryptic digests of fragment C124-298 of penicilloylated serum albumin, obtained from a penicillin-treated patient or prepared by in vitro conjugation, were analyzed by HPLC. Determinations of benzyl penicilloyl groups (BPO) were performed on the different fractions. Three BPO-containing peptides were identified by their amino acid sequence and the bound BPO was located on lysines 190, 195 and 199 and serine 193. These four main BPO-binding sites are all located on a very short region (10 amino acid residues) of the albumin molecule at the junction of domains 1 and 2.

Amino Acid Sequence↗
PubMed1989

Histamine content, diamine oxydase and histidine decarboxylase activities along the intestinal tract of the rat.

Histamine is widely distributed in the intestine where it is involved in many pathological reactions. The relations between histamine content, diamine oxidase and histidine decarboxylase activity have been investigated along rat's intestine. Results showed significant variations along the intestine. A correlation was observed between histamine and histidine decarboxylase (p less than 0.01), both of them being even in the small intestine (11.8 +/- 2.3 ng/mg ww and 112.5 +/- 21.2 fmoles/hr/mg ww respectively), significantly higher in the caecum (16.3 +/- 1.9 and 178 +/- 20.1) and significantly smaller in the colon (7.3 +/- 1.1 and 65.3 +/- 11.5) than in other intestinal segments. Diamine oxydase activity was higher in ileum (30.7 +/- 7.2 pmoles/min/mg ww) than in jejunum (17.1 +/- 2.8), caecum (4.3 +/- 0.8) and colon (2.6 +/- 2.7), and could not be linked to histamine content. The results fitted in the hypothesis that histamine in rat intestine is mainly located in mast cells where HDC is probably the main enzyme involved in its modulation.

Amine Oxidase (Copper-Containing)↗
PubMed1988

Histamine distribution in the gastrointestinal wall of germ free and conventional chicken: evidence of the role of the digestive microflora.

The digestive microflora produces a decrease of the mucosal histamine content in the wall of the chicken colon but has no significant incidence in the upper part of the digestive tract. The anatomical and physiological particularities of the chicken digestive tract permitted to observe that wall histamine concentration depends on different factors. Endogenous factors control the wall histamine content in the proventriculus, independantly of the diet and/or of the presence of a microflora. Diet has a specific incidence upon the gastrointestinal wall of the host in the crop and in the colon. The colon microflora decreases the effect of the diet essentially when the chicken are fed a semi synthetic diet. Interactions between the diet and the microflora could induce physiopathological manifestations.

Animals↗
PubMed1985

Histamine and mast cell distribution in the gastrointestinal wall of the rat: comparison between germ-free and conventional rats.

The distributions of histamine and mast cells in the intestinal mucosa have been studied in conventional (CV) and germ-free (GF) rats. Both distributions do not appear to be uniform throughout the gastrointestinal tract. The presence of digestive microflora influences these distributions: more histamine and mucosal mast cells are present in the small intestine of CV than in GF rats. Paradoxically the opposite is observed in the large intestine. Differences in mast cell counts in the crypt area of the small intestine (higher in CV than in GF rats) confirm the role of microflora on crypt cell proliferation due to a mild chronic inflammation. In the large intestine, however, the microflora appears to have a more complex influence and could act indirectly on histamine turnover.

Animals↗
PubMed1985

Disposition and metabolism of chloramphenicol in trout.

The urinary and faecal excretion, tissue distribution and metabolism of 3H-chloramphenicol (CP) were measured in rainbow trout, Salmo gairdneri R., after a single 50 mg/kg intragastric dose. The major route of excretion of 3H was faecal (64.3% of the dose), with approx. 16% in the urine in five days. Radioactivity was widely distributed in trout tissues and organs, the highest concen. being in the bile and intestine. At 48 h after dosing, the radioactivity remaining in the liver, the muscle and the perigastric adipose tissue was as CP-derived compounds bound to tissues. In addition to unchanged CP (4.3% dose after 96 h), the other metabolites excreted in the urine were CP base (5.2%), CP alcohol (4.0%) and CP glucuronide (1.8%).

Adipose Tissue↗
PubMed1983

Comparative metabolism of chloramphenicol in germfree and conventional rats.

The action of gut microflora on the metabolism of chloramphenicol (CP) was studied in germfree (GF) and conventional (CV) rats after administration of single oral doses of tritiated CP. There were similarities in the metabolic pathways of CP in the GF and CV animals, i.e., rapid absorption, hepatic glucuroconjugation, and biliary excretion of the CP conjugate. CP, CP-oxamic acid, CP-alcohol, and CP-base were present in similar proportions in the urine of both GF and CV rats. Differences observed included the slow elimination of total radioactivity and a reduced proportion of the urinary excretion versus the fecal excretion in the GF Reduction products which were present in much greater quantities in the urine and feces of CV rats are compatible with the generally described hydrolysis of the CP-glucuronide, followed by a nitroreduction of the CP by the gut microflora and the reabsorption of a part of the products formed. In GF rats, CP-glucuronide was the major fecal metabolite, a portion of it having been reabsorbed and excreted in the urine. Although in lesser amounts, reduction products were still present as urinary metabolites in GF rats. Such a reduction in the tissues might produce active intermediate that could be related to CP toxicity.

Animals↗
PubMed1983

Liquid chromatographic determination and mass spectrometric confirmation of chloramphenicol residues in animal tissues.

A rapid and sensitive liquid chromatographic (LC) method for determination of trace amounts of chloramphenicol (CP) in animal tissues has been developed. Chloramphenicol identity is confirmed by gas chromatography-mass spectrometry (GC-MS). CP can be routinely quantitated by LC at 10 ppb with 75% recovery, and GC-MS selected ion monitoring permits complete identification at concentrations as low as 5 ppb. Residues were determined in chicken tissues after intramuscular injection of CP. Depletion was rapid with no residues detected in muscle after 8 h, while 15-30 ppb CP was still determined and identified in the liver.

Animals↗