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Biomedical subjects

M Adam

Publications and source records attributed to M Adam.

At least 73 records · Page 4Linked to original sources
PubMed1995

Reactivity and the fate of some composite bioimplants based on collagen in connective tissue.

Three composite materials based on collagen gel prepared with ISC40 and supplemented with the tripeptide glycine-histidine-lysine (GHK) mixed with bioglass (BAS O), pure hydroxyapatite (grain: 0.5-1.0 microns and 13-23 microns) and shredded beef bone were tested in the laboratory rat and guinea-pig. In the course of 49 d, no signs of infectious inflammation or incompatibility were observed around subcutaneously installed bioimplants. Particles of glass and hydroxyapatite became subject to phagocytosis. Bone fragments were completely resorbed, and no signs of osteogenic activity were detected in the neighbourhood.

Amino Acid Sequence↗
PubMed1995

Effect of the tripeptide glycyl-L-histidyl-L-lysine on the proliferation and synthetic activity of chick embryo chondrocytes.

Under certain conditions chondrocytes form lattices with cartilage collagens, which may serve as cartilage implants. It is necessary to find the optimal conditions for culturing chondrocytes. Three different supports are compared: (a) plastic; (b) cartilage collagens; and (c) insoluble skin collagen solubilized under denaturing conditions (ISC-40). The effect of culture medium supplementation with the tripeptide (Gly-His-Lys)2.Cu.2H2O.2NaCl (GHK) on chondrocyte proliferation and synthetic activity is studied, with particular attention paid to collagen types I, II and III. The collagen supports stimulated chondrocyte proliferation, but on the ISC-40 support they started to dedifferentiate rather early. In the primary culture, chondrocytes on all three supports synthesized mainly collagen type II, and only small amounts of types I and III. In the first passage the synthesis of these two collagen types increased, relative to collagen type II, at least on the cartilage collagen support. Supplementation of culture medium with GHK stimulated chondrocyte proliferation in the primary structure mostly on the ISC-40 support. On the other two types of supports the stimulatory effect of GHK was expressed mostly in the first passages. The collagen synthetic rate was increased by GHK on both of the collagen supports; on the cartilage collagen support collagen type II was synthesized predominantly and on the ISC-40 support types I and III were mostly formed. It is suggested that supplementation of culture medium with GHK may be useful in the preparation of cartilage implants.

Amino Acid Sequence↗
PubMed1995

[Hemophagocytic syndrome in children infected by HIV. Apropos of 3 cases].

BACKGROUND: The hemophagocytic syndrome has previously been reported in different infectious diseases (EBV, CMV, tuberculosis...) but rarely in adults with AIDS and never in children suffering from AIDS. CASE REPORTS: A hemophagocytic syndrome was recognized during the follow-up of 3 children with AIDS. The first, a 9-year-old girl developed an acute EBV coinfection and was treated with shots of corticosteroids and vepesid but died shortly afterwards. The second patient, a 3-year-old girl was infected with Aspergillus fumigatus for which she was given amphotericin B with a rapid improvement. The third patient, an 8-year-old boy had multi-resistant Streptococcus pneumoniae otitis and pneumonitis; his condition improved rapidly with adapted antibiotherapy. DISCUSSION: The HIV-hemophagocytic syndrome is not exceptional in HIV infection because of the association of immunodeficiency and resulting superinfections. Its diagnosis and treatment should be etiologic. Severe cases without etiology could benefit from chemotherapy. CONCLUSION: Management and outcome of this potentially lethal syndrome might depend on the identification of a curable infectious cause.

AIDS-Related Opportunistic Infections↗
PubMed1995

Development and validation of two enzyme-linked immunosorbent assay (ELISA) methods for recombinant hirudin.

Recombinant hirudin is currently being developed as a potential prophylactic and therapeutic antithrombotic drug in various clinical indications such as angina and deep venous thrombosis. In this report, we have discussed the production of specific polyclonal antibodies to recombinant hirudin (rH) and the development of two ELISA methods to measure rH concentrations in biological fluids: a sandwich and a competitive ELISA method. Intra- and inter-assay variations in the two methods are extremely low (3-7%). The competitive ELISA method is rapid, simple and highly reproducible. Saturation binding curves, selection of appropriate incubation times, recovery of different hirudin variants and reactivity in the presence of thrombin are discussed. The methods can be easily adapted to monitor hirudin concentrations in the clinical laboratory for diagnostic purposes as well as for performing pharmacokinetic studies.

Antibody Specificity↗
PubMed1995

Replication-defective adenovirus type 5 as an in vitro and in vivo gene transfer vector in chickens.

The capacity of E1A gene-deleted and thus replication-defective adenovirus type 5 (Ad5) to transduce foreign genes in chicken embryo fibroblasts (CEF) as well as in chickens was investigated. The lacZ and luciferase genes were successfully transduced in CEF by replication-defective Ad5, demonstrating that these cells possess receptor(s) for binding and penetration of Ad5. A single intramuscular inoculation of Ad-gD, a replication-defective Ad5 harbouring the gD gene of pseudorabies virus, in adult and 1-day-old chickens led to the production of a very high titres of specific antibodies. These gD-specific antibodies persisted for at least 56 days. These results demonstrate that replication-defective Ad5, despite its mammalian origin and the deletion of the E1A gene, is a good candidate for developing non-spreading vaccines in poultry.

Adenovirus E1A Proteins↗
PubMed1995

Isogenic adenoviruses type 5 expressing or not expressing the E1A gene: efficiency as virus vectors in the vaccination of permissive and non-permissive species.

We have previously constructed a recombinant adenovirus type 5 (Ad5) vector expressing the gD gene of pseudorabies virus (Ad-gD). In this virus the E1A gene was deleted, so that Ad-gD was replication defective. When high doses of this virus were inoculated into target species, it was nevertheless able to elicit a strong and protective immune response. We have restored a functional E1A gene in Ad-gD, by rescuing the E1A transcription unit in an ectopic position, far from the enhancer sequences of E1A. Unlike Ad-gD, this new virus (Ad-gD-E1A) was able to replicate in non-transcomplementing Vero cells. The kinetics of replication of Ad-gD-E1A were similar to that of the wild-type Ad5 when cells were infected at medium or high m.o.i. Nevertheless, the level of virus replication was low when Ad-gD-E1A was plated at low m.o.i. Cotton rats and mice were vaccinated once with 10(9) to 10(5) TCID50 of each of the two viruses. In both species, Ad-gD and Ad-gD-E1A induced similar antibody responses for each dose tested. Both were able to give a high level of protection against the challenge. However, the protective dose of Ad-gD-E1A was at least 250-fold lower in cotton rats, an Ad5-permissive species, than that of Ad-gD. In mice, a species restricted for Ad5 replication, the protective dose of Ad-gD-E1A was still not significantly different from that of Ad-gD. These data indicate that the protective dose of such an adenovirus vector vaccine for an animal species is strictly linked to the capacity of the virus to replicate in this species, at least in the model used. So, in designing an adequate vector one needs to balance the use of low dose vaccines against risks in terms of biosafety. Nevertheless, for diseases in which the protective immune response is mainly based on the antibody response, defective and non-defective adenovirus vectors should demonstrate similar protective doses.

Adenoviridae Infections↗
PubMed1994

[The effect of aluminum on the structure and metabolism of collagen].

BACKGROUND: Aluminium is considered to be the etiopathogenetic factor in various pathological conditions. It was demonstrated already previously that metals even under conditions in vivo link with collagen structures and influence the protein metabolism. Therefore the authors investigated the effect of aluminium (Al) on collagen and its metabolism. METHODS AND RESULTS: In the described trial aluminium was used as potassium alum, oxalate alum or aluminium chloride. The effect of aluminium was investigated in rats, chick embryos or fibroblast cultures. Using electron microscopy of collagen from the tail tendons, the development of transverse striation following 15 weeks of i.m. Al administration was revealed. At the same time also an increase of temperature of contraction of this collagen by 1.5 to 3.7 degrees C occurred, depending on the Al compound used. On fibroblast cultures an inhibitory effect of Al on their proliferation was found. In chick embryos Al caused a decline of the radioactive hydroxyproline concentration and thus also a reduced collagen synthesis practically in all investigated tissues. Similarly the negative effect of Al was manifested in the incorporation of radioactive glucosamine into proteoglycans of granulation tissue of rats. In cartilaginous collagen enhanced proline hydroxylation caused by Al was observed. CONCLUSIONS: Although it is not possible, with regard to Al chemistry, to make an unequivocal statement on the nature of the compound which causes a particular reaction in biological systems, it may be said, based on the achieved results, that Al has an effect on biological systems due to its bond with collagen structures and by influencing their metabolism.

Aluminum↗
PubMed1994

Cloning, functional expression, and characterization of the human prostaglandin E2 receptor EP2 subtype.

A cDNA clone encoding the human prostaglandin (PG) E2 receptor EP2 subtype has been isolated from a human lung cDNA library. The 1.9-kilobase pair cDNA, hEP2, encodes for a 488-amino acid protein with a predicted molecular mass of 53,115 and has the seven putative transmembrane domains characteristic of G protein-coupled receptors. The specific binding of [3H]PGE2 to COS cell membranes transfected with the hEP2 cDNA was of high affinity with an equilibrium dissociation constant (Kd) of 1 nM and the rank order of potency for prostaglandins in competition for [3H]PGE2 specific binding was PGE1 = PGE2 >> iloprost > PGF2 alpha > PGD2. In competition studies using more selective prostanoid-receptor agonist and antagonists, the [3H]PGE2 specific binding was competed by MB28767, an EP3 agonist, but not by the EP1-preferring antagonists AH6809 and SC19220, or by the EP2 agonist butaprost. Electrophysiological studies of Xenopus oocytes co-injected with hEP2 and cystic fibrosis transmembrane conductance regulator (cAMP-activated Cl- channel) cDNAs detected PGE2-specific inward Cl- currents, demonstrating that the hEP2 cDNA encoded a functional receptor which produced an increase in cAMP levels. Thus, we have cloned the human EP2 receptor subtype which is functionally coupled to increase in cAMP. Northern blot analysis showed that hEP2 is expressed as a 3.8-kilobase mRNA in a number of human tissues with the highest expression levels present in the small intestine.

Amino Acid Sequence↗
PubMed1994

[Intracavernous auto-injection of prostaglandin E1 for diagnosis and treatment of erectile dysfunction].

34 impotent patients were offered auto-injection therapy and all except 2 began treatment. Prostaglandin E1 (PGE) was used regularly for a mean of 8.6 months (range 1-17). The onset of erection was 5-30 min (mean 11.4) after injection and it lasted at least 30 min (mean 106.2 min). An erection of more than 6 hrs was observed in only 2 patients. There have been no instances of cavernous fibrosis, chemical priapism or systemic reactions. The most common adverse effect was penile pain after injection. It was mild to moderate in 4 patients (11.7%), and in only 1 was it severe enough to require stopping treatment. Overall, intracavernous injection of PGE appears to be safe, effective treatment for impotence without side-effects other than pain after injection in a few.

Adult↗
PubMed1994

Characterization of protein tyrosine phosphatase SH-PTP2. Study of phosphopeptide substrates and possible regulatory role of SH2 domains.

The src homology 2 (SH2) domain containing protein-tyrosine-phosphatase SH-PTP2, was over-expressed in Escherichia coli for a kinetic study employing a set of synthetic 13- to 14-mer phosphopeptide substrates. The full-length SH-PTP2 protein, as well as a truncated form, lacking the two amino terminus SH2 domains (SH-PTP2(delta SH2)), exhibited Michaelis-Menten kinetics, and demonstrated striking substrate preferences on phosphopeptides having sequences based on sites of intracellular protein tyrosine phosphorylation. For example, while a KM of 59 microM and kcat/KM of 1.1 x 10(5) were obtained using SH-PTP2(delta SH2) and PDGFRY1021, a phosphorylation site within the platelet-derived growth factor receptor, other peptides revealed no detectable phosphate release. PDGFRY1009, modeled after a sequence identified as an in vivo binding site for SH-PTP2, was also a good substrate for this enzyme. The truncated form, lacking the SH2 domains demonstrated higher catalytic efficiency than the full-length enzyme. Interestingly, soluble SH2 domains were found to inhibit the catalytic activity of SH-PTP2 in a concentration-dependent manner. There was also evidence of a non-phosphotyrosine-mediated association between the two domains. These observations suggested that the SH2 domains have a direct role in regulating the catalytic activity of SH-PTP2.

Amino Acid Sequence↗
PubMed1994

Engineering and overexpression of periplasmic forms of the penicillin-binding protein 3 of Escherichia coli.

Replacement of the 36 and 56 N-terminal amino acid residues of the 588-amino-acid-residue membrane-bound penicillin-binding protein 3 (PBP3) of Escherichia coli by the OmpA signal peptide allows export of F37-V577 PBP3 and G57-V577 PBP3 respectively into the periplasm. The modified ftsI genes were placed under the control of the fused lpp promoter and lac promoter/operator; expression of the truncated PBP3s was optimized by varying the copy number of the recombinant plasmids and the amount of LacI repressor, and export was facilitated by increasing the SecB content of the producing strain. The periplasmic PBP3s (yield 8 mg/l of culture) were purified to 70% protein homogeneity. They require the presence of 0.25 M NaCl to remain soluble. Like the membrane-bound PBP3, they undergo processing by elimination of the C-terminal decapeptide I578-S588, they bind penicillin in a 1:1 molar ratio and they catalyse hydrolysis and aminolysis of acyclic thioesters that are analogues of penicillin. The membrane-anchor-free PBP3s have ragged N-termini. The G57-V577 PBP3, however, is less prone to proteolytic degradation than the F37-V577 PBP3.

Amino Acid Sequence↗
PubMed1994

Cloning and expression of three isoforms of the human EP3 prostanoid receptor.

Functional cDNA clones coding for three isoforms of the human prostaglandin E receptor EP3 subtype have been isolated from kidney and uterus cDNA libraries. The three isoforms, designated hEP3-I, hEP3-II and hEP3-III, have open reading frames corresponding to 390, 388 and 365 amino acids, respectively. They differ only in the length and amino acid composition of their carboxy-terminal regions, beginning at position 360. The human EP3 receptor has seven predicted transmembrane spanning domains and therefore belongs to the G-protein-coupled receptor family. The rank order of potency for prostaglandins and related analogs in competition for [3H]PGE2 specific binding to membranes prepared from transfected COS cells was comparable for all three isoforms, and as predicted for the EP3 receptor, with PGE2 = PGE1 >> PGF2 alpha = iloprost > PGD2 >> U46619. In addition, the EP3-selective agonist MB28767 was a potent competing ligand with an IC50 value of 0.3 nM, whereas the EP1-selective antagonist AH6909 gave IC50 values of 2-7 microM and the EP2-selective agonist butaprost was inactive. In summary, we have cloned three isoforms of the human EP3 receptor having comparable ligand binding properties.

Amino Acid Sequence↗
PubMed1994

Enhancement of the efficacy of a replication-defective adenovirus-vectored vaccine by the addition of oil adjuvants.

We previously constructed a recombinant adenovirus with a defective E1A gene, which expresses high levels of the pseudorabies virus gp50 in non-transcomplementing cells. The virus is unable to replicate in mice. It elicited the production of anti-gp50 antibodies only when high concentrations (10(8) TCID50 per dose) of the virus were used and it gave mice little protection. The combination of the recombinant adenovirus at several concentrations (10(8), 10(7.4), 10(6.4) TCID50 per dose) with certain oil adjuvants in different galenic forms (water-in-oil, oil-in-water, water-in-oil-in-water) led to an increase in specific antibody responses and protection for the host when challenged with a virulent pseudorabies virus under very severe conditions, i.e. where 100% of unvaccinated mice died. A water-in-oil-in-water formulation induced a very high level of anti-gp50 antibodies even with a low concentration of adenovirus. These results could be correlated to the induction of cytokines, such as IL6, which is observed with this galenic form. The oil-adjuvanted emulsions induced IL2, suggesting that they were able to activate T-helper cells. Different oil formulations elicited the different IgG subclasses (IgG1, IgG2a, IgG2b, IgG3). These results can be extended to other live replication-defective vaccines expressing different proteins.

Adenoviruses, Human↗
PubMed1994

Vaccination of pigs with replication-defective adenovirus vectored vaccines: the example of pseudorabies.

The efficacy of a recombinant human adenovirus type 5 expressing gD, one of the immunogenic glycoprotein of pseudorabies virus, was tested in pigs. Due to the deletion of the E1a gene, the recombinant virus is unable to replicate in non transcomplementing cells but is capable of eliciting an immune response against gp50 after inoculation into animals. The virus was formulated in a water/oil/water emulsion, a strategy previously shown to enhance the immune response against the virus-induced gp50. Pigs of 18-25 kg were vaccinated twice and the recombinant virus was not isolated from nasal and rectal swabs taken after each injection of the vaccine. High levels of neutralizing antibodies were induced by the vaccination. Protection against a severe challenge was effective, as measured by growth performance (dG = 1.73), and reduction of the time of excretion of the challenge strain (mean time: 4.4 days for the vaccinated and 7.9 days for the control pigs). These results show that non replicating adenoviruses are able to induce a strong protective immune response against foreign genes in pigs, which may be of general interest for the design of pig vaccines.

Adenoviruses, Human↗
PubMed1994

The effect of different collagens and of proteoglycan on the retraction of collagen lattice.

The effect of various collagens and proteoglycan on the formation and retraction of collagen lattices was tested. The most rapid aggregation of collagen molecules was observed by the use of the least cross-linked collagen fractions (ie pepsin-digested calf skin collagen type I). Lattices formed with more cross-linked collagens (acid soluble collagen-ASC, type III) contracted slowly and less intensively. Unpurified pepsinized cartilage extract containing collagen types II, IX and XI, some glycoproteins and proteoglycans formed lattices rather well. On the contrary, purified collagen type II as well as polymeric collagen (solubilized by denaturing conditions) did not form lattices at all. The lattice formation and retraction was intensified by addition of proteoglycan into the culture medium. The authors suggest that the kinetics of the lattice formation and retraction depends on the amount of collagen cross-links and the concentration of proteoglycan in the culture medium.

Collagen↗
PubMed1994

Anaplastic Wilms' tumour, a subtype displaying poor prognosis, harbours p53 gene mutations.

The genetics of Wilms' tumour (WT), a paediatric malignancy of the kidney, is complex. Inactivation of the tumour suppressor gene, WT1, is associated with tumour aetiology in approximately 10-15% of WTs. Chromosome 17p changes have been noted in cytogenetic studies of WTs, prompting us to screen 140 WTs for p53 mutations. When histopathology reports were available, p53 mutations were present in eight of eleven anaplastic WTs, a tumour subtype associated with poor prognosis. Amplification of MDM2, a gene whose product binds and sequesters p53, was excluded. Our results indicate that p53 alterations provide a molecular marker for anaplastic WTs.

Alleles↗