Kinetics of anti-major histocompatibility complex antibodies after plasma exchange and immunosuppression in a pig model.
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Animals↗
Biomedical subjects
C Renard
Publications and source records attributed to C Renard.
Age-related increase of porcine natural interferon alpha producing cell frequency and of interferon yield per cell.
Porcine blood mononuclear cells (PBMC) were shown to secrete interferon alpha (IFN-alpha) after induction by a coronavirus, the transmissible gastroenteritis virus (TGEV). IFN-alpha producing cells, referred to as natural interferon alpha producing (NIP) cells, were detected by an ELISPOT assay using anti-porcine IFN-alpha monoclonal antibodies. The frequency of NIP cells among blood cells is low, at most 40-110 per 10(5) PBMC and each NIP cell was found to produce several units of IFN. We have shown that NIP cell frequency and IFN yield per cell gradually increased with the age of the donor animals, from the neonatal period to the adult age, with a significant increase around puberty. Our present results also indicate that NIP cells may be influenced by physiological and genetic factors; thus (1) NIP cell frequency and IFN yield per cell were decreased during lactation; (2) Chinese (Meishan) pigs were found to have higher NIP cell frequency and IFN yield per cell than European (Large White) animals.
Aging↗
Steady-state properties of a model ternary substrate cycle: theoretical predictions.
Numerous ternary substrate cycles are metabolically operative in vivo. The relative concentrations of the interconverted substrates are generally correlated with different physiological states. These cycles often include reversible and/or substrate-inhibited enzymic steps. The switch between one steady state (metabolic state) and another may be the consequence of either the effect of an exogeneous metabolite or signal, or the alteration of a cycle internal parameter. The interpretation of results obtained with currently designed experiments on substrate cycles seldom take into account the very dynamic and regulatory properties inherent in the cyclic and often autocatalytic nature of the pathway. In the present report, the various dynamic properties of a model ternary substrate cycle, bounded by moiety conservation, are investigated. Three situations with increasing complexity are considered: (i) the three enzymes are michaelian and catalyse irreversible steps; (ii) one of the enzymic steps is reversible; and (iii) one step is subjected to a destabilizing factor, i.e. inhibition by excess of substrate. The behavior(s) of the whole cycle is mainly controlled by four parameters, that is, ST, the total concentration of the substrate pool, and the three enzyme maximal velocities, VMi (i = 1,2,3). As ST (= S1 + S2 + S3) is constant, the Si steady-state concentrations (stable or not) can be represented in barycentric coordinates in a triangle (simplex). This convenient representation allows us to predict the different states of the system when one enzyme maximal activity is varied. The steady-state concentration dependencies as a function of one or several parameters may be either monostable (possibility of zero-order ultrasensitivity) or bistable (with or without reversible transitions). The physiological and experimental relevances of these observations are emphasized.
Enzyme Stability↗
Anti-major histocompatibility complex antibody removal assay in a swine model.
A swine model of anti-MHC (SLA) immunization by skin grafting was established with the aim of removing preformed anti-MHC antibodies and preventing their resynthesis, in a situation close to that of hyperimmunization in humans. Plasma exchange therapy with or without associated immunosuppressive therapy was used. The feasibility of this animal model in terms of anti-MHC immunization and its therapeutic management have been proven. However, frequent early deaths of animals still mar the experimental protocol. Synchronization of plasma exchange and subsequent cyclophosphamide pulses seemed to abolish the antibody rebound phenomenon and cause marked drop of anti-MHC antibodies. Restimulation by a new skin graft is responsible for an intense polyclonal antibody stimulation, which suggests that we have to be careful in grafting patients with positive historical crossmatches and negative current ones.
Animals↗
Marked genetic polymorphism of the swine steroid 21-hydroxylase gene, and its location between the SLA class I and class II regions.
Restriction fragment length polymorphism (RFLP) analysis of the swine 21-hydroxylase (CYP21) region was conducted on 31 unrelated SLA class I typed pigs, mainly Large Whites, including 15 haplotypes. Ten haplotypes were from SLA genotypic homozygotes and five were from SLA class I phenotypic homozygotes. DNA digestion with Hin dIII, TaqI and PstI, and hybridization to a 4.5-kb swine CYP21 genomic probe yielded respectively two, four and three RFLP patterns. Six patterns were identified with combined RFLP. In addition, analysis of the CYP21 region in families comprising several SLA recombinants demonstrated that the CYP21 gene lies in the DNA segment between the SLA class I and class II regions. These overall results reinforce our previous conclusion about the existence in the pig of a single 21-hydroxylase gene. The characterization of at least six CYP21 allelic patterns provides a new tool for studying the associations between the SLA region and zootechnical traits.
Alleles↗
The swine steroid 21-hydroxylase gene (CYP21): cloning and mapping within the swine leucocyte antigen complex.
A swine genomic cosmid library constructed from a genotypically SLA homozygous Large White individual was screened with a murine genomic 21-hydroxylase probe. A clone which contained a pig 21-hydroxylase gene was isolated and after subcloning, the 5' region of the gene was sequenced. The deduced amino acid sequence corresponded almost exactly to the NH2 terminal portion of the steroid 21-hydroxylase from porcine adrenal microsomes. Comparison of the first 99 amino acid residues of both sequences revealed three substitutions comprising two leucine residues in positions 10 and 13, and one arginine residue in position 55 for our sequence, instead of threonine in position 10 and lysine in position 13 and 55 for the isolated enzyme. A swine homologous probe was derived from the isolated 21-hydroxylase gene and used for gene assignment by RFLP studies in two swine leucocyte antigen (SLA) informative families. The results demonstrate that the swine 21-hydroxylase gene is located within or close to the swine MHC. Taken together, the present results suggest the existence of a single 21-hydroxylase gene per haploid genome.
Animals↗
Swine lymphocyte alloantigens (SLA) class I serology and genetics in Belgian Landrace and Pietrain breeds.
Eighty anti-SLA class I reagents were prepared resulting from skin graft and subcutaneous immunizations in 320 fattening pigs of the Belgian Landrace and Pietrain breeds. By means of these alloantisera seven internationally and five locally established specificities were recognized. Three of the locally assigned specificities were new: BM 36, BM 37 and BM 38. They were serologically and genetically defined. The typing battery was completed with French and Danish reagents, and correlation coefficients were calculated for the main alloantisera recognizing SLA class I alloantigens observed in the Belgian breeds. The SLA haplotype frequencies were estimated in 372 Belgian Landrace and 369 Pietrain pigs. The SLA haplotype distribution differs significantly between both breeds and the genetic distance (0.54) at the SLA system is quite high.
Animals↗
Beta-glucan and pectin derivatives stimulate prolactin secretion from hypophysis in vitro.
Previous work has shown that various plant extracts administered to animals stimulate milk protein synthesis through the secretion of prolactin. It has also been shown that beta-glucan and pectin are the active molecules capable of stimulating prolactin release in vivo after intravenous injections. In this work, it is shown that beta-glucan and several pectin derivatives are able to stimulate prolactin secretion from hypophysis fragments incubated for 2 hr in a synthetic medium.
Animals↗
Quantification of rat T-kininogen using immunological methods. Application to inflammatory processes.
Antibodies raised in rabbits against rat T-kininogen (alpha 1-cysteine proteinase inhibitor) were used to develop a radioimmunoassay and a nephelometric quantification for T-kininogen. These assays were specific and analytically reliable. We also described a radioimmunoassay for kinin measurement. These immunological methods have been used to study the behaviour of T-kininogen during inflammatory processes and specify the two properties of this kind of kininogen: its inhibitory capacity towards cysteine proteinases and its activity as precursor of T-kinin. Control plasma level of T-kininogen in male rats was lower than that of female rats. The maximum level was observed in plasma, liver, kidney and uterus of female rats during metestrus. After turpentine injection, T-kininogen level increased not only in plasma but also in liver and kidney. In carrageenan-induced peritoneal exudates, we found a large accumulation of T-kininogen and of immunoreactive kinins, these latter being identified by HPLC as bradykinin.
Animals↗
Possible relationships between SLA and porcine reproduction.
The possible influence of the pig major histocompatibility complex on reproductive traits is reviewed. Among the parameters investigated, significant associations were observed between SLA and genital tract development in males. Several SLA haplotypes affected either positively or negatively the development of testes, the epididymes and the Cowper's glands, whereas the influence of these haplotypes on androsterone tissue content was limited. The impact of the SLA complex on female reproductive performance has been more difficult to ascertain, although some results suggest that the SLA region may interfere with ovulation rates. The influence on prolificacy of SLA sharing between sires and dams was also investigated. Even if fertilization rate is not affected, embryonic mortality and preimplantation embryo development might be influenced by the pig MHC region. Although the litter size was not only marginally affected by the SLA complex, there is one case where SLA identity between the boar and several related sows led to significantly reduced litter size. In these families piglets homozygous for a particular SLA haplotype were almost absent, suggesting the existence of a recessive lethal gene linked to SLA.
Animals↗
[The SLA major histocompatibility complex of swine].
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Animals↗
Coupling products of amino acids to penicillin V and cephalothin: synthesis and susceptibility to carboxypeptidases and lysosomal enzymes.
Amino acids have been coupled to the carboxyl group of penicillin V and cephalothin by methods that keep the beta-lactam ring intact. Derivatives were successfully obtained with both neutral (Leu, Val, Ala, Ile, Trp, Tyr, Gly) and one acidic (Glu) amino acids. The new compounds were inactive in vitro against Staphylococcus aureus or Micrococcus luteus. Incubation in the presence of purified carboxypeptidases (A, B), soluble lysosomal fractions from liver, or cellular homogenates from liver, kidney, fibroblasts, and macrophages did not allow recovery of the antibacterial activity. Injection in mice also failed to cause liberation of microbiologically active compounds. HPLC studies confirmed that the amide linkage between the antibiotic and the amino acid was not hydrolyzed in the presence of soluble lysosomal fractions from liver. However, conversion of cephalothin and cephalothin-leucine to desacetyl derivatives was observed in the presence of soluble lysosomal fractions and extracts from liver and semipurified orange peel acetylesterase(s). It is concluded that amino acid derivatives of beta-lactam antibiotics do not offer potential chemotherapeutic use as prodrugs.
Amino Acids↗
Joint report of the first international comparison test on swine lymphocyte alloantigens (SLA).
The first international comparison test on swine lymphocyte alloantigens (SLA) was held in Helsinki, Finland in July 1986. The results reported were based on a comparison of 157 alloantisera originating from six laboratories. The antisera were tested against a selected panel of 264 lymphocyte samples belonging to four laboratories. The most common breeds in Europe were chosen for this first comparison test (Landrace and Large White). Eighteen of the 31 previously known specificities were confirmed and a new nomenclature was established.
Animals↗
In-vivo studies on Haemaccel-fibronectin interaction in man.
An enzyme-linked immunoassay has been recently set up for direct measurement of the binding capacity of plasma fibronectin to gelatin. This binding capacity could be completely inhibited in vitro by an eight-fold excess of gelatin, of Haemaccel, but not of Geloplasma. On the contrary, the levels of immunoreactive fibronectin measured by laser nephelometry did not change, in presence of 10 to 1000 micrograms ml-1 of gelatin, of Haemaccel or of Geloplasma. When infused into normal volunteers, Haemaccel provoked a strong and immediate inhibition of the plasma fibronectin binding capacity to gelatin. This inhibition was dose-dependent and maximal after infusion of 500 ml of Haemaccel. Twenty-four hours after this infusion, there was a progressive recovery of the gelatin-binding capacity, which was almost completely achieved 96 h later. The formation of complexes between Haemaccel and fibronectin was demonstrated by gel filtration chromatography and by affinity chromatography. Immunoreactive plasma fibronectin levels remained unchanged up to 24 h after infusion of 500 ml of Haemaccel. A transient decline to 50% of its initial value then occurred the second day after the infusion. Therefore, a delay existed between the formation of fibronectin-Haemaccel complexes and their elimination from the bloodstream. This delay decreased when smaller volumes of Haemaccel were infused, which strongly suggests that plasma fibronectin is cleared by means of Haemaccel and does not seem to play a role of opsonin in these conditions.(ABSTRACT TRUNCATED AT 250 WORDS)
Chromatography, Affinity↗
Influence of conversion of penicillin G into a basic derivative on its accumulation and subcellular localization in cultured macrophages.
beta-Lactam antibiotics do not accumulate in phagocytes, probably because of their acidic character. We therefore synthesized a basic derivative of penicillin G, namely, 14C-labeled N-(3-dimethylamino-propyl)benzylpenicillinamide (ABP), and studied its uptake and subcellular localization in J774 macrophages compared with that of 14C-labeled penicillin G. Whereas the intracellular concentration (Ci) of penicillin G remained lower than its extracellular concentration (Ce), ABP reached a Ci/Ce ratio of 4 to 5. Moreover, approximately 50% of intracellular ABP was found associated with lysosomes after isopycnic centrifugation of cell homogenates in isoosmotic Percoll or hyperosmotic sucrose gradients. The behavior of ABP was thus partly consistent with the model of de Duve et al. (C. de Duve, T. de Barsy, B. Poole, A. Trovet, P. Tulkens, and A. Van Hoof, Biochem. Pharmacol. 23:2495-2531, 1974), in which they described the intralysosomal accumulation of weak organic bases in lysosomes. Although ABP is microbiologically inactive, our results show that beta-lactam antibiotics can be driven into cells by appropriate modification. Further efforts therefore may be warranted in the design of active compounds or prodrugs that may prove useful in the chemotherapy of intracellular infections.
Animals↗
Thallium 201 muscle scintigraphy: application to the management of patients with arterial occlusive disease.
Skull (S), thigh (T), and calf (C) scintigraphies were performed by using 2 mCi thallium 201 IV in 30 patients suffering from stages II, III, and IV arterial occlusive disease (Fontaine's classification). Two indexes were calculated: P = T/C-C/S (T/C and C/S were the absolute values of radioactivity ratios measured before medical treatment) and R = delta(C/S)-delta(T/C) (where delta expressed the relative variation of the ratios measured after treatment and compared with initial values). Angiography was performed on all patients prior to treatment, and the results were quantified as 1 in the case of obliteration and 0.5 in case of stenosis of major arterial axes. Clinical improvement was demonstrated by a 100% increase in walking distance for stage II disease, abolition of pain at rest for stage III disease, and reepithelialization of trophic lesions for stage IV disease. Paraclinical effectiveness was evaluated by measuring ankle systolic pressure (SP) and index (SI) before and after treatment. The correlation observed between the values of P and angiography results was p less than 0.025 (Student t-test). The mean of P (measured before treatment) was 1.75 for the improved patients and 0.56 for the others (p less than 0.005). After treatment, R was +58% for improved patients versus -13% in those in whom the treatment was inefficient (p less than 0.025). P expresses the microcirculatory effects of arterial lesions detected by angiography. It is a prognostic index: satisfactory proximal perfusion (high T/C), associated with lesions that are essentially peripheral (low C/S), predicting a positive effect of medical treatment.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Hydrolysis of Pro-Ala dipeptides by lysosomal hydrolases. Models for the study of lysosomotropic amino acid prodrugs of penicillins.
Peptidic lysosomotropic prodrugs of antibiotics and antitumoral agents could be of advantage in chemotherapy, providing that free, active drug is released at, or close to, the desired site of action. Thus, aminoacyl derivatives of doxorubicin, e.g., where the drug is attached to the amino acid by a primary amino function, are sensitive to lysosomal hydrolases. We have examined whether a similar approach can be used for drugs carrying a carboxyl group such as beta-lactam antibiotics. Because the C adjacent to the carboxyl group in beta-lactams has the D configuration, we have examined and report here the synthesis and susceptibility of model peptides, namely Boc-D-Pro-L-Ala and Boc-L-Pro-L-Ala to lysosomal hydrolases. Hydrolysis of the D isomer proceeds considerably more slowly than that of the L isomer. Lysosomal carboxypeptidase(s) and/or amidases appear therefore to have a much narrower specificity than aminopeptidase(s), which will severely limit the applicability of the concept of peptidic lysosomotropic prodrugs.
Animals↗
Effect of swine lymphocyte antigen haplotypes on birth and weaning weights in pigs.
Birth weights of 708 live piglets and weaning weights of 566 piglets were used to investigate the effect of the swine lymphocyte antigen (SLA) complex on these traits in Large White pigs. Piglets were from litters of a long-term selection experiment to measure response for selection to increase litter size. SLA haplotypes were determined using conventional class I antisera. A total of 14 haplotypes were detected. The effect of SLA haplotype on birth and weaning weights was investigated using a statistical model that included the effects of experimental group, sire, dam, sex and SLA haplotype. Results indicated that SLA class I haplotype 13.1.3 increased birth weights (P less than 0.10) and significantly increased weaning weights (P less than 0.01). This effect of haplotype 13.1.3 on weaning weight was 605 +/- 215 g (0.3 standard deviations). SLA class I homozygosity did not appear to affect birth and weaning weights. These results suggest that the SLA complex plays an important role in early growth in the pig and that further study of SLA effects on growth and reproduction are warranted.
Animals↗