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D Atlan

Publications and source records attributed to D Atlan.

At least 37 records · Page 2Linked to original sources
PubMed1998

[Carcinoma of the endometrium: review of the literature].

In endometrial adenocarcinoma, many risk factors have been demonstrated. Among them, tamoxifene is a factor of low risk. Any endometrial bleeding requires a gynecological exam in order to make an early diagnosis. The positive histologic diagnosis is more often after surgery which is necessary for histo-prognostic stage. Non conservative hysterectomy with pelvic lymphadenectomy (obturator chain) is recommended for the most frequent stages I and II. Radiation therapy alone is recommended for stage III. Palliative therapy (hormonotherapy or chemotherapy) could be proposed for the few stage IV.

Adenocarcinoma↗
PubMed1996

A new cell surface proteinase: sequencing and analysis of the prtB gene from Lactobacillus delbruekii subsp. bulgaricus.

Investigation of the chromosomal region downstream of the lacZ gene from Lactobacillus delbrueckii subsp. bulgaricus revealed the presence of a gene (prtB) encoding a proteinase of 1,946 residues with a predicted molecular mass of 212 kDa. The deduced amino acid sequence showed that PrtB proteinase displays significant homology with the N termini and catalytic domains of lactococcal PrtP cell surface proteinases and is probably synthesized as a preproprotein. However, the presence of a cysteine near the histidine of the PrtB active site suggests that PrtB belongs to the subfamily of cysteine subtilisins. The C-terminal region strongly differs from those of PrtP proteinases by having a high lysine content, an imperfect duplication of 41 residues, and a degenerated sequence compared with the consensus sequence for proteins anchoring in the cell walls of gram-positive bacteria. Finally, the product of the truncated prtM-like gene located immediately upstream of the prtB gene seems too short to be involved in the maturation of PrtB.

Amino Acid Sequence↗
PubMed1995

Tamoxifen for the treatment of metastatic inflammatory breast carcinoma.

In this series, 65 patients with metastatic inflammatory breast carcinoma were treated with neoadjuvant chemotherapy followed by local regional treatment followed by adjuvant chemotherapy. All of these selected patients developed further metastatic disease and were treated at that time with tamoxifen alone. Measurements of hormone receptor levels were available for 46 patients. Four tumors were positive estrogen receptors and eight tumors were positive progesterone receptors. The objective response rate for tamoxifen therapy was 5% (3/65). No major side effects were observed. When the metastasis-free interval was over 19 months, the overall survival and after metastases survival rates were significantly increased. Our conclusion is that tamoxifen should not play any role in the palliative treatment of metastases in inflammatory breast carcinoma.

Adenocarcinoma↗
PubMed1994

Cloning, sequencing and characterization of the pepIP gene encoding a proline iminopeptidase from Lactobacillus delbrueckii subsp. bulgaricus CNRZ 397.

The proline iminopeptidase (PepIP) of Lactobacillus delbrueckii subsp. bulgaricus is a major peptidase located in the cell envelope. Its structural gene (pepIP) has been cloned into pUC18 and expressed at a very high level in Escherichia coli to give a PepIP activity 15,000-fold higher than that found in L. delbrueckii subsp. bulgaricus. The nucleotide sequence of the pepIP gene revealed an open reading frame of 295 codons encoding a protein with a predicted M(r) of 33,006, which is consistent with the apparent size of the gene product. The amino acid sequence of PepIP shows significant homology with those of other hydrolases involved in the degradation of cyclic compounds. In particular, there is a region which includes an identified catalytic site containing a serine residue and a motif specific for the active sites of prolyloligopeptidases (Gly-X-Ser-X-Gly-Gly). The PepIP opens a new way for supplying cells with proline using the peptides resulting from the proteolytic degradation of caseins.

Amino Acid Sequence↗
PubMed1994

Proline iminopeptidase from Lactobacillus delbrueckii subsp. bulgaricus CNRZ 397: purification and characterization.

Proline iminopeptidase (PepIP) is a major peptidase in Lactobacillus delbrueckii subsp. bularicus CNRZ397, encoded by the pepIP gene. Amplification and expression of this gene in Escherichia coli K12 resulted in a very high level of enzyme production. Moreover, export into the E. coli periplasm of 45% of PepIP activity allowed us to purify the enzyme easily by a single ion-exchange chromatography step. PepIP is a trimer of Mr 100000 , composed of three identical subunits. In the presence of 0.1% BSA, PepIP activity was optimal at pH 6-7 and stable at temperatures below 40 degrees C. The enzyme was strongly inhibited by 3,4-dichloroisocoumarin, a serine protease inhibitor, by bestatin and by heavy metal ions. It was also inactivated by p-chloromercuribenzoate, but was reactivated by adding dithiothreitol. PepIP is characterized by a high specificity towards di- or tripeptides with proline at the NH2-terminal position, but is not able to hydrolyse longer peptides, or peptides with hydroxyproline at the NH2-end. The NH2-terminal amino acid sequence of the purified PepIP corresponds to the amino acid sequence deduced from the nucleotide sequence of the pepIP gene.

Amino Acid Sequence↗
PubMed1993

Two cell-wall-associated aminopeptidases from Lactobacillus helveticus and the purification and characterization of APII from strain ITGL1.

Lactobacillus helveticus ITGL1 is able to hydrolyse many amino-acyl and dipeptidyl-p-nitroanilides. Analysis of heat inactivation kinetics, metal ion and protease inhibitor effects, and the subcellular location of aminopeptidase activities in both the parental strain and mutants deficient in lysyl-p-nitroanilide hydrolysis, led to the characterization of two cell-wall-associated aminopeptidases, APII and APIV. APII, which catalysed L-lysine p-nitroanilide hydrolysis, was purified about 28-fold to homogeneity from cell-wall extracts of L. helveticus ITGL1 and characterized. The purified enzyme appeared to be monomeric, with a molecular mass of 97 kDa. Aminopeptidase activity was greatest at pH 6.5 and 50 degrees C. APII was completely inhibited by bestatin, chelating agents such as EDTA or 1,10-phenanthroline and the divalent cations Zn2+ and Cu2+. The activity of the EDTA-treated enzyme was restored by Co2+, Ca2+ or Mn2+. Although APII was able to degrade several dipeptides and tripeptides with hydrophobic N-terminal amino acid (Leu, Ala), it was inactive on peptides containing Pro or Gly, and may thus contribute to the development of cheese flavour by processing bitter peptides.

Amino Acid Sequence↗
PubMed1992

[Primary neuroendocrine cutaneous carcinoma or Merkel cell carcinoma. Review of the literature].

The neuroendocrine carcinomas of the skin, also called Merkel cell carcinomas, are unusual malignancies mostly observed in the elderly. They are diagnosed by a pathologist: ultrastructural studies and immunohistochemistry support the diagnosis. The prognosis is poor. Lymph nodes and metastases quickly arise although sometimes, they are discovered immediately. A combination of surgery and radiotherapy is recommended. Metastases and unresectable tumors should be treated by chemotherapy.

Carcinoma, Merkel Cell↗
PubMed1991

Cell-wall-associated proteinase of Lactobacillus delbrueckii subsp. bulgaricus CNRZ 397: differential extraction, purification and properties of the enzyme.

Whole cells of Lactobacillus delbrueckii subsp. bulgaricus CNRZ 397 were able to hydrolyse alpha- and beta-caseins. Irrespective of the growth medium used, milk or De Man-Rogosa-Sharpe (MRS) broth, identical patterns of alpha- and beta-casein hydrolytic products, respectively, were visualized by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. A soluble proteinase present in cell-wall extracts was active on caseins and displayed the same hydrolytic patterns as whole cells. It was purified from cell-wall extract to homogeneity by ultrafiltration and ion exchange chromatography. The enzyme is a monomer with a molecular mass of 170 kDa, an optimum temperature of 42 degrees C and an optimum pH of 5.5. It was strongly activated by dithiothreitol and partially inhibited by E-64. These properties indicate that cysteine residues play an important role in the enzyme mechanism. The purified proteinase was not able to hydrolyse di- or tripeptides.

Amino Acid Sequence↗
PubMed1990

X-Prolyl-Dipeptidyl Aminopeptidase of Lactobacillus delbrueckii subsp. bulgaricus: Characterization of the Enzyme and Isolation of Deficient Mutants.

Lactobacillus delbrueckii subsp. bulgaricus CNRZ 397 is able to hydrolyze X-proline-para-nitroanilides and X-proline-beta-naphthylamides (X for alanyl- or glycyl-). A single metal-independent cytoplasmic enzyme with a molecular weight estimated to be 82,000 is responsible for these activities and was named X-prolyl-dipeptidyl aminopeptidase (X-Pro-DPAP). Isolation and analysis of mutants totally deficient for X-Pro-DPAP activity showed that a total lack of this enzyme induces (i) a decrease in the growth rate; (ii) an increase in cell wall proteinase activity; (iii) the loss of three cell wall proteins with respective molecular masses of 16, 40, and 52 kilodaltons; and (iv) enhancement of a cell wall protein with a molecular mass of 150 kilodaltons. The involvement of X-Pro-DPAP in casein catabolism is discussed.

Journal Article↗
PubMed1989

Isolation and Characterization of Aminopeptidase-Deficient Lactobacillus bulgaricus Mutants.

Lactobacillus bulgaricus CNRZ 397 is able to hydrolyze many amino-acyl- and dipeptidyl-beta-naphthylamides. Analysis of heat inactivation kinetics, protease inhibitor effects, and the subcellular location of aminopeptidase (AP) activities from the parental strain and mutant derivatives dificient in alanyl- or leucyl-beta-naphthylamide hydrolysis pointed out the existence of four APs. All mutants isolated were totally deficient in AP II, a cell wall metallo-enzyme with a broad substrate specificity but that is specifically responsible for lysyl-AP activity and is characterized by a molecular mass of 95,000 daltons. AP I and AP III are cytoplasmic enzymes that exhibit arginyl-AP activity; both enzymes are inducible during growth in rich peptide MRS medium (Difco Laboratories, Detroit, Mich.). The existence of a fourth AP (AP IV) that is involved in leucyl-AP activity was suggested. Moreover, we showed that X-prolyl-dipeptidyl-AP activity, which was not catalyzed by an AP, involved an enzyme(s) that is controlled by a regulatory mechanism that is common to that of AP II.

Journal Article↗
PubMed1986

Effects of pho regulatory mutations and phoA gene amplification on alkaline phosphatase synthesis and release by lky mutants of Escherichia coli K12.

lky mutants of Escherichia coli K12 spontaneously released alkaline phosphatase (APase) into the extracellular medium to give up to 300 units ml-1. APase is a phosphate repressible periplasmic enzyme encoded by the gene phoA. With a view to establishing a method of easy purification, we have analysed APase synthesis and release patterns of isogenic lky strains containing either a constitutive pho regulatory mutation, or a hybrid plasmid carrying the structural gene phoA+ and pho regulatory genes, or a transducing phi 80 phoA+ phage. In the presence of the phoS2333 mutation, F- lky strains lysogenized with phi 80 phoBin phoA+ phage and grown in high phosphate medium were able to release eight times more APase activity (2300 units ml-1) than haploid strain 2336 (phoS+ lky) grown in low phosphate medium. Neither protein synthesis, the cell export machinery nor leakage mechanisms were limiting for APase release. Sufficient APase was released into the medium to facilitate its purification.

Alkaline Phosphatase↗
PubMed1985

Excretion of alkaline phosphatase by Escherichia coli K-12 pho constitutive mutants transformed with plasmids carrying the alkaline phosphatase structural gene.

Escherichia coli alkaline phosphatase constitutive mutants carrying a pst or a phoS mutation and a plasmid-bearing gene phoA+ excreted into the growth medium up to 50% of the total alkaline phosphatase production. This excretion was pH dependent and did not involve drastic modifications of the cell envelope. Alkaline phosphatase accounted for 80% of total released proteins. Amplification of gene phoA+ was a necessary condition for excretion to occur. When the beta-lactamase structural gene bla+ was coamplified with gene phoA+, both enzymes were excreted. pst-transformed excretory strains did not show the pleiotrophic phenotype previously described for lky mutants.

Alkaline Phosphatase↗