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Biomedical subjects

A Joly

Publications and source records attributed to A Joly.

At least 37 records · Page 2Linked to original sources
PubMed1997

Cyclosporine A is an uncompetitive inhibitor of proteasome activity and prevents NF-kappaB activation.

Cyclosporine A is an immunosuppressive agent that is used clinically in the prevention of transplant rejection and development of graft-versus-host disease. Recently, cyclosporine A has been shown to possess anti-inflammatory properties and is capable of inhibiting lipopolysaccharide-induced NF-kappaB activation. Ubiquitin-mediated proteasomal proteolysis plays a critical role in signal-induced NF-kappaB activation since it regulates both IkappaB degradation and p105 processing, it is also involved in the production of peptides for the assembly of MHC class I molecules. We report here that cylcosporine A acts as an uncompetitive inhibitor of the chymotrypsin-like activity of the 20S proteasome in vitro and that it suppresses lipopolysaccharide-induced IkappaB degradation and p105 processing in vivo demonstrating that inhibition of proteasome proteolysis is the mechanism by which cyclosporine A prevents NF-kappaB activation. A structurally unrelated immunosuppressant, rapamycin, did not inhibit the 20S proteasome in vitro.

Animals↗
PubMed1997

The involvement of an LPS inducible I kappa B kinase in endotoxin tolerance.

When human ovarian carcinoma cells are challenged with endotoxin, an I kappa B kinase is transiently induced within 3 to 5 min. This enzyme activity causes the hyperphosphorylation and subsequent degradation of I kappa B which allows NF-kappa B to translocate to the nucleus where it activates transcription. When endotoxin treated cells are rechallenged with a second dose of LPS, I kappa B kinase is not detected and I kappa B remains in the cytoplasm where it sequesters NF-kappa B. We report here the absence of endotoxin inducible I kappa B kinase activity in endotoxin tolerant cells suggesting that I kappa B kinase may play an important role in endotoxin tolerance. When cells tolerant to endotoxin are treated with TNF, I kappa B kinase activity is induced. Thus cells that are endotoxin tolerant are not cross tolerant to TNF. Dexamethasone, a known inhibitor of NF-kappa B activation does not inhibit endotoxin dependent induction of I kappa B kinase suggesting that the mechanism of action of dexamethasone is different from the tolerance mechanism reported here.

Base Sequence↗
PubMed1997

Survival, proliferation, and functions of porcine hepatocytes encapsulated in coated alginate beads: a step toward a reliable bioartificial liver.

Orthotopic liver transplantation is the most effective treatment for fulminant hepatic failure. As an alternative treatment, an efficient extracorporeal bioartificial liver should contain a large yield of functional hepatocytes with an immunoprotective barrier, for providing temporary adequate metabolic support to allow spontaneous liver regeneration or for acting as a bridge toward transplantation. Survival, proliferation, and functions of porcine hepatocytes were evaluated in primary cultures and after embedding in alginate beads, which were subsequently coated with a membrane made by a transacylation reaction between propylene glycol alginate and human serum albumin. Disruption of total pig livers by collagenase perfusion/recirculation allowed the obtention of up to 10(11) hepatocytes with a viability greater than 95%. Hepatocytes in conventional cultures or embedded in coated alginate beads survived for about 10 days, secreted proteins, particularly albumin, and maintained several phase I and II enzymatic activities, namely ethoxyresorufin-O-deethylase, oxidation of nifedipine to pyridine, phenacetin deethylation to paracetamol, glucuroconjugation of paracetamol, and N-acetylation of procainamide. Typical features of mitosis and [3H]thymidine incorporation indicated that porcine hepatocytes proliferated in both conventional cultures and alginate beads. The efficacy of the membrane surrounding alginate beads for protecting cells from immunoglobulins was tested by embedding HLA-typed human lymphocytes, which were subsequently incubated with specific anti-HLA immunoglobulin G and complement. These data show that large yields of porcine hepatocytes that are embedded in coated alginate beads remain functional and are isolated from large molecular weight molecules, such as immunoglobulins. This system represents a promising tool for the design of an extracorporeal bioartificial liver, containing xenogeneic hepatocytes, to treat acute liver disease in humans.

Acetaminophen↗
PubMed1997

N-acetyl-leucinyl-leucinyl-norleucinal inhibits lipopolysaccharide-induced NF-kappaB activation and prevents TNF and IL-6 synthesis in vivo.

The effects of N-acetyl-leucinyl-leucinyl-norleucinal (ALLN), a potent inhibitor of proteolysis catalyzed by proteasomes, on the activation of NF-kappaB in vitro and in vivo have been examined. Confirming earlier observations, ALLN inhibits the activation of NF-kappaB in macrophage cultures stimulated with LPS, resulting in the intracellular accumulation of IkappaB and p105. The synthesis of TNF, a reaction dependent upon NF-kappaB activation, is blocked by ALLN. Treatment of mice with LPS results in the induction of TNF and IL-6 within 90 min followed by lethal shock at 24 hr. In mice pretreated with ALLN, serum TNF and IL-6 levels were significantly lower than those in untreated animals. These studies suggest that the proteasome is a novel target for the identification of agents that may be useful in the treatment of those diseases whose etiology is dependent on the activation of NF-kappaB.

Animals↗
PubMed1997

Evidence for inflammatory and secretagogue lipids in cyst fluids from patients with autosomal dominant polycystic kidney disease.

Advanced autosomal dominant polycystic kidney disease (ADPKD) is characterized morphologically by massive cyst enlargement, moderate interstitial infiltration with mononuclear cells, and extensive fibrosis. In patients affected by a common genotype (PKD1), it has been suggested that the progressive decline in renal function that transpires over a highly variable time course may be due to endogenous or exogenous epigenetic factors. We have postulated that a neutral lipid, discovered in human cyst fluid and stimulating the rates of transepithelial fluid secretion and cellular proliferation of renal epithelial cells in vitro may have a potential role in cyst growth and the progressive decline of kidney function. In this study, we used thin-layer chromatography (TLC) and high-performance TLC (HPTLC) to determine whether lipid extracts of human cyst fluid stimulated monocyte chemotaxis in vitro. Monocyte chemotactic activity, determined by the transmembrane migration of murine RAW 264.7 cells, was stimulated (delta 26.0 +/- 1.5 optical density units) by a lipid fraction less polar than sphingosine but more polar by TLC and HPTLC than 1-monooleoylglycerol. A high level of secretagogue activity was detected in this fraction (delta 0.336 +/- 0.022 microliter/cm2 1 hr) and to a lesser extent (delta 0.253 +/- 0.022 microliter/cm2/hr) in a neighboring fraction that encompassed the 1-monooleoylglycerol standard. Cyst fluid with undetectable secretagogue activity had a monocyte chemotactic-activity level only 18% as great as fluids with high levels of secretagogue activity. The secretagogue and chemotactic activities in TLC-HPTLC fractions were resistant to treatment with KOH, but both were diminished by HCl, borohydride, or periodate. Rat proximal tubule cultures incubated with oleate complexed with albumin elaborated secretagogue and chemotactic activities in the conditioned medium, with TLC-HPTLC mobility characteristics similar to the biologically active cyst fluid lipids. On the basis of these studies, we conclude that human cyst fluids harbor potent secretagogue and chemotactic lipids that may have a role in determining the functional course of ADPKD. On the basis of preliminary chemical characterizations, we suggest that the secretatogue and monocyte chemotactic activities of cyst fluid may reflect the action of lipid molecules of similar structure, the source of which may be renal epithelial cells.

Animals↗
PubMed1996

Cell-based therapy of acute liver failure: the extracorporeal bioartificial liver.

The need for an alternative treatment to orthotopic liver transplantation for acute liver failure is a major issue, and systems capable of temporarily providing liver functions are being actively tested. Liver assist devices based on detoxication by dialysis or hemoperfusion through various membranes or cartridges proved to be inefficient because of their lack of metabolic function. An extracorporeal hybrid bioartificial liver might be an appropriate treatment, since it can provide liver-specific functions, maintain the patient alive, and allow spontaneous recovery of the patient's own liver or act as a bridge toward liver transplantation. Many devices have been proposed, including flat culture substrates, hollow-fiber bioreactors, or microcarriers, using xenogenic hepatocytes or hepatoma cell lines. Various drawbacks of these devices led us to attempt to develop a reliable extracorporeal bioartificial liver based on alginate bead-entrapped hepatocytes. This system was used successfully for the correction of the Gunn rat genetic defect, which results in lack of bilirubin conjugation. The development of this system for clinical purposes requires large yields of functional hepatocytes. We have isolated normal porcine hepatocytes by collagenase perfusion of the liver. Cells were immobilized in membrane-coated alginate gel beads, which were subsequently inoculated into a bioreactor. Porcine hepatocytes expressed liver-specific functions at high levels, particularly protein neosynthesis and enzymatic activities involved in detoxication and biotransformation processes. In addition, hepatocytes entrapped in coated alginate beads were isolated from immunoglobulins. This system represents a promising tool for the design of an extracorporeal bioartificial liver in human beings.

Animals↗
PubMed1996

[Analgesia controlled by the patient in pediatrics].

The development of patient controlled analgesia (PCA) in children is the result of a search for an analgesia being both maximally efficient and secure, in the management of severe pain. The technique is based on self infusions of an analgesic, mainly morphine, by the child, through a special pump. The quality of the pump is essential in order to exclude any risk of overdosage. In order to prevent potential secondary effects and complications, a careful supervision is mandatory (clinical, by pulse oximetry, regular checking of pump parameters). PCA is applicable to children older than 5 years. The main indications are post-operative and oncological pains.

Adolescent↗
PubMed1996

[Abdominal syndromes and analgesia].

Despite physiological advances and recent progress in pain relief, early analgesia for patients with acute abdominal pain is not a conventional endpoint. In clinical practice, priority is often given to diagnosis and management decisions. There are few controlled trials to settle the issue and opinions are still divided. recent studies suggest than early and effective analgesia in acute abdomen does not interfere with diagnosis, and even facilitates initial examination. Various modes of analgesia can be considered.

Abdominal Pain↗
PubMed1996

[A step towards a bioartificial liver: temporary extracorporeal replacement using isolated hepatocytes].

The mortality rate of fulminant hepatic failure is about 80%. Besides orthotopic liver transplantation, specific therapies are not currently available. Indeed, not only removal of toxins is required, by means of dialysis or hemoperfusion, but specific hepatic functions must be provided to allow spontaneous liver regeneration or as a bridge before liver transplantation. Treatment with an extracorporeal bioartificial liver is an attractive approach. This system was successfully used for the correction of the Gunn rat genetic defect which results in the lack of bilirubin conjugation. The development of this system for clinical purpose requires both a large yield of functional hepatocytes and their immunoprotection in an appropriate device. We have isolated normal porcine hepatocytes by collagenase perfusion of the liver; cells are subsequently entrapped within membrane-coated alginate beads which are inoculated in a bioreactor. Plasma from an animal undergoing fulminant hepatic failure by end-to-site portocaval shunt and whole porta hepatic tightening circulates within the bioreactor. Porcine hepatocytes express liver-specific functions at high levels, particularly secretion of plasma proteins and several enzyme activities involved in the detoxication and biotransformation of xenobiotics. In addition, hepatocytes are immunoseparated from circulating immunoglobulins. Ethical concerns are discussed in the field of physiopathology, immunopathology and public health, as a prerequisite to create departments of Cell Therapy, in the near future.

Animals↗
PubMed1994

[Pain conduction tracts. From physiology to practice].

Some new theories concerning pain physiology have recently been suggested. Experimental facts show that despite its complexity, neuroplasticity is an established fact. The concept of preemptive analgesia is about to receive clinical applications. Nevertheless, the role of many opioid ligands which are involved in the pain physiology can explain the efficacy of some analgesia techniques. The authors review the physiological process of pain from its periphery to its centre and the ensuing practical applications. They point out the difficulty to apprehend peripheral analgesia, and the necessity of further researches concerning especially NMDA spinal receptors and other specific receptors.

Animals↗
PubMed1994

[Production of partial blastulas by parthenogenesis in Xenopus].

In mature Xenopus eggs, the cell cycle can be triggered by pricking the egg or by an electric shock. However, no cleavage occurs unless centriole-containing fractions or isolated centrosomes are injected at the time of egg activation. We have obtained for an average of one heterologous centrosome injected per oocyte a complete parthenogenetic development. We also observed that the success rate of blastula formation declined linearly with the time elapsing between oocyte activation and centrosome injection. Moreover, in most cases, large areas of the blastulas remained uncleaved, interfering with gastrulation and blocking further development.

Animals↗
PubMed1993

Effect of site-directed mutagenesis of conserved aspartate and arginine residues upon farnesyl diphosphate synthase activity.

All polyprenyl synthases catalyze the condensation of the allylic substrate, isopentenyl diphosphate, with a specific homoallylic diphosphate substrate. Polyprenyl synthases from Homo sapiens, Ratus rattus, Escherichia coli, Saccharomyces cerevisiae, Neurospora crassa, and Erwinia herbicola contain two conserved "aspartate-rich domains" (Ashby, M.N., and Edwards, P.A. (1992) J. Biol. Chem. 267, 4128-4136). In order to determine the importance of these domains in catalysis, the conserved aspartates or arginines in domains I and II of rat farnesyl diphosphate synthase were individually mutated to glutamate or lysine, respectively. The putative "active site" arginine (Brems, D.N., Breunger, E., and Rilling, H. C. (1981) Biochemistry 20, 3711-3718) was mutated to lysine. Each mutant enzyme was overexpressed in E. coli and purified to apparent homogeneity. Detailed kinetic analyses of the wild type and mutant enzymes indicated that mutagenesis of Asp104, Asp107, Arg112, Arg113, and Asp243 resulted in a decreased Vmax of approximately 1000-fold compared to wild type. However, no significant change in the Km values for either the isopentenyl diphosphate or geranyl diphosphate substrate were observed. The results strongly suggest that these amino acids, and to a lesser extent Asp244, are involved in either the condensation of isopentenyl diphosphate and geranyl diphosphate to form farnesyl diphosphate and/or the release of the farnesyl diphosphate product from farnesyl diphosphate synthase. The conservation of these amino acid residues in different enzymes from several species suggests that these domains play a similar role in other polyprenyl synthases.

Alkyl and Aryl Transferases↗
PubMed1991

In vitro identification of a soluble protein:geranylgeranyl transferase from rat tissues.

The gamma subunit of mammalian trimeric G proteins has been shown previously to be modified in vivo on a cysteine residue situated at the carboxyl-terminal sequence-Cys-Ala-Ile-Leu-COOH by a 20-carbon prenyl moiety geranylgeranyl (Mumby, S. M., Casey, P. J., Gilman, A. G., Gutowski, S., and Sternweis, P. C. (1990) Proc. Natl. Acad. Sci. U.S.A. 87, 5873-5877; Yamane, H. K., Farnsworth, C. C., Xie, H., Howald, W., Fung, B. K-K., Clarke, S., Gelb, M. H., and Glomset, J. A. (1990) Proc. Natl. Acad. Sci. U.S.A. 87, 5866-5872). A biotinylated peptide acceptor comprising the eight carboxyl-terminal amino acids of the gamma subunit and tritiated geranylgeranyl diphosphate were utilized to monitor a protein:prenyl transferase activity in rat organs of varying age. The transferase activity was dependent upon the presence of divalent metal ions and maximal activity was achieved with either 1 mM ZnCl2 or 20 mM MgCl2. Activity was shown to be linear with respect to time, protein concentration, substrate concentration, and the pH optimum was 7.5. Protein:geranylgeranyl transferase activity was detected in all rat organs studied with the highest specific activity in brain S100. No activity was detected in the membrane fraction. The specific activity in brain, liver, kidney, and heart increased with age. Radioactivity incorporated into the peptide acceptor from both [1-3H]geranylgeranyl diphosphate and [5-3H]mevalonate by 21-day-old rat brain S100 was released by treatment with methyl iodide, and in both cases, analysis of the cleavage products by reversed phase high performance liquid chromatography showed a peak of radioactivity co-eluting with a geranylgeraniol standard which was well resolved from a farnesol standard. This indicated that the rat brain S100 contained not only the protein:geranylgeranyl transferase but also geranylgeranyl synthetase activity and that the peptide acceptor was specific for geranylgeranyl under the conditions tested.

Age Factors↗
PubMed1991

Posterior approach to the rectum for treatment of selected benign lesions.

Access to lesions in the mid-rectum can be difficult. This report summarizes our experience with a posterior approach to the rectum in 22 men and 13 women, age range 21 to 96 years. Surgical indications included villous tumours, rectal prolapse, rectal strictures or rectal fistulae. No postoperative complications were observed in 20 patients, but fistulae developed in seven patients, of whom three required proximal colostomy and surgical treatment. Four healed spontaneously. Two patients developed sacrococcygeal hernia. Pathologic examination of villous tumour showed extensive malignant change in three cases requiring rectal resection with end-to-end colo-anal anastomosis. In two patients mild incontinence developed, treated by biofeedback. Residual peri-anal pain was reported by two patients. The posterior approach to the rectum is particularly useful for benign lesions too high for a transanal resection and too low for a transabdominal resection.

Adenoma↗
PubMed1991

Sphincter repair without overlapping for fecal incontinence.

Forty patients who had sphincter repair by one surgeon over the last 15 years were reviewed. The etiology of sphincter trauma was previous surgery (22), childbirth (14), and accidental trauma (4). Eleven patients had undergone at least one previous attempt at repair. Prior to operation, 12 patients were incontinent for liquid stool and 28 for formed stool. A technique of sphincter repair without overlapping was used. An associated diverting colostomy was carried out on seven patients who had had a previous failed repair. Follow-up was an average of 17 months after operation (range, 2-96 months). After operation, 25 patients were completely continent, 6 had occasional leaks of liquid stool, 4 were continent for solid stool only, and 5 showed no improvement. Neither diverting colostomy nor overlapping sutures appear to be mandatory for a successful repair of the anal sphincter after trauma.

Adolescent↗
PubMed1991

[Cancer of the rectum in elderly patients over the age of seventy-five years. Results of the surgical treatment].

The authors reviewed 122 rectal cancers observed over a period of 14 years in patients over the age of 75 years. Sixty-eight patients underwent extensive rectal resection, 17 were treated by local excision, and 28 only underwent a colostomy. Eight patients were excluded for surgery. The analysis of all of these groups showed that perioperative mortality was greater for large resections than for local resections, but with a lower recurrence rate and a higher survival at 3 years. Survival at 5 years after large resections was very close to the natural life expectancy for people of the same age. Moreover, survival was the quality of more comfortable than after local excision, and operative mortality was generally due to organ failure rather than to age itself. Radical surgery does not have to be systematically refused for very old patients, but he discussed in terms of the patients general status.

Actuarial Analysis↗