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F Gauthier

Publications and source records attributed to F Gauthier.

At least 19 recordsLinked to original sources
PubMed1992

Inhibition of rat tissue kallikrein gene family members by rat kallikrein-binding protein and alpha 1-proteinase inhibitor.

The regulation of tissue kallikrein activity by plasma serine proteinase inhibitors (serpins) was investigated by measuring the association rate constants of six tissue-kallikrein family members isolated from the rat submandibular gland, with rat kallikrein-binding protein (rKBP) and alpha 1-proteinase inhibitor (alpha 1-PI). Both these serpins inhibited kallikreins rK2, rK7, rK8, rK9 and rK10 with association rate constants in the 10(3)-10(4) M-1.s-1 range, whereas only 'true' tissue kallikrein rK1 was not susceptible to alpha 1-PI. This results in slow inhibition of rK1 by plasma serpins, which could explain why this kallikrein is the only member of the gene family identified so far that induces a transient decrease in blood pressure when injected in minute amounts into the circulation.

Animals↗
PubMed1992

An immunochemical approach to investigating the mechanism of inhibition of cysteine proteinases by members of the cystatin superfamily.

Antibodies were raised against a synthetic dodecameric peptide KGAGQVVAGPWK (K12K), encompassing sequences thought to be important for the function of the cysteine proteinase inhibitors of the cystatin superfamily. These antibodies specifically recognized molecules of family 3, i.e., kininogens, in the serum of seven mammalian species tested in this study. The only notable exception was that of rat thiostatin (T kininogen) which is structurally related to the kininogen family. The antibodies also discriminated between family 2 (cystatins) and family 3 (kininogens) of the cystatin superfamily, since neither chicken cystatin nor human and rat cystatins C and S, which all belong to family 2 were recognized. The cystatin-like inhibitory domains resulting from fragmentation of human low molecular weight kininogen by bovine trypsin, were still recognized by antibodies, indicating that discrimination does not require two neighbouring inhibitory sites on the kininogen heavy chain. The antibodies blocked the capacity of kininogens to inhibit papain, suggesting that they recognize a conformational epitope at or near the kininogen inhibitory sites. The inhibitory properties of family 2 cystatins remained unchanged, confirming that members of this family do not interact with anti K12K antibodies. These antibodies are thus a new tool able to discriminate functionally and structurally between the members of the cystatin superfamily.

Amino Acid Sequence↗
PubMed1992

Protein products of the rat kallikrein gene family. Substrate specificities of kallikrein rK2 (tonin) and kallikrein rK9.

Two closely related kallikrein-like proteinases having little activity toward the standard synthetic amide substrates of tissue kallikreins were isolated from the rat submandibular gland. They were found to be the protein products of the rKlk2 (tonin) and the rKlk9 genes by amino acid sequence analysis (nomenclature of the genes and proteins of the kallikrein family is according to the proposal of the discussion panel from the participants of the KININ '91 meeting held Sept. 8-14, 1991, in Munich, Germany). These two proteinases of similar structure also had very similar physicochemical properties. They differed from other kallikrein-related proteinases in having high pHi values of 6.20 (rK2) and 6.85 (rK9). Kallikrein rK2 was purified as a single peptide chain, whereas rK9 appeared as a two-chain protein after reduction. Their enzymatic properties were also very similar and differed significantly from those of other rat kallikrein-related proteinases. Unlike the five other kallikrein-related proteinases we have purified so far, kallikrein rK9 was not inhibited by aprotinin. rK9 also differed from rK2 by its tissue localization. The prostate gland contained only rK9 where it was the major kallikrein-like component. The amino acids preferentially accommodated by the proteinase S3 to S2' subsites were identified using synthetic amide and protein substrates. Unlike other kallikrein-related proteinases, rK2 had a prevalent chymotrypsin-like specificity, whereas rK9 had both chymotrypsin-like and trypsin-like properties. Both rK2 and rK9 preferred a prolyl residue in position P2 of the substrate and did not accommodate bulky and hydrophobic residues at that position, as did most of the other kallikrein-related proteinases. This P2-proline-directed specificity is necessary for processing the precursors of several biologically active peptides. Subsites accommodating residues COOH-terminal to the scissile bond were also important in determining the overall substrate specificity of these proteinases. rK2 and rK9 both showed a preference for hydrophobic residues in P2'. Other subsites upstream of the S3 subsite were found to intervene in substrate binding and hydrolysis. The restricted specificity of rK2 and rK9 is consistent with the presence of an extended substrate binding site, and hence with a processing enzyme function. Their P1 specificities enabled both proteinases to release angiotensin II from angiotensinogen and from angiotensinogen I, but rK9 was at least 100 times less active than rK2 on both substrates. The substrate specificities of rK2 and rK9 were correlated with key amino acids defining their substrate binding site.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗
PubMed1992

Production of the cysteine proteinase inhibitor cystatin C by rat Sertoli cells.

The Sertoli cells of the rat testis produce cystatin C, a cysteine proteinase inhibitor. Primary culture of Sertoli cells secreted both unglycosylated and glycosylated forms of rat cystatin C. Despite the low concentration of cystatin C in rete testis fluid, equilibrium dissociation constants (Ki) for the interaction between cystatin C and lysosomal cathepsins indicate that this molecule could be involved in the local regulation of testicular cysteine proteinase activity which may be necessary for spermatogenesis and spermiogenesis.

Amino Acid Sequence↗
PubMed1992

Immunological characterization of rat kininogens with monoclonal antibodies to T-kininogen. Distinction between the different domains of T-kininogen and the multiple rat kininogens.

A panel of 16 monoclonal antibodies (mAb) were produced against rat T-kininogen to characterize this family of proteins. These mAbs bound 125I-T-kininogen by radioimmunoassay as well as reacting strongly with immobilized T-kininogen in an enzyme-linked immunosorbent assay (ELISA). The reactivity of these antibodies with proteolytic fragments of T-kininogen demonstrated the recognition of several different epitopes. One antibody was specific for the domain 1 of the heavy chain and/or the light chain, twelve antibodies were specific for domain 2 and three antibodies were specific for domain 3. All monoclonal antibodies recognized the two forms of T-kininogen encoded by the two different T-kininogen genes, TI and TII kininogen, except antibody TK 16-3.1 which uniquely reacted with TII kininogen. Two antibodies recognizing domain 2 cross-reacted with the high-molecular-mass kininogen (H-kininogen), whereas all the other monoclonal antibodies were specific to T-kininogen and did not recognize the heavy chain of H-kininogen. None of the antibodies tested altered the thiol protease inhibitory activity of T-kininogen, its partial proteolysis by rat mast cell chymase or the hydrolysis of H-kininogen by rat urinary kallikrein. The use of these antibodies in the development of sensitive ELISA to measure T-kininogen levels in plasma, urine, liver microsomes and hepatocytes is described. Two different forms of T-kininogen were distinguished by these monoclonal antibodies in Western blotting using rat plasma. The localization of T-kininogen was defined using these monoclonal antibodies by immunohistochemistry in rat liver hepatocytes and rat kidney.

Animals↗
PubMed1992

Functional diversity of proteinases encoded by genes of the rat tissue kallikrein family.

A group of proteinases closely related to tissue kallikrein was purified from the rat submandibular gland. Physicochemical characterization of these proteinases, including amino terminal sequencing, allowed correlation with the genes of the rat kallikrein family. In spite of their similar structure, these proteinases have different substrate specificities and different susceptibilities to inhibitors which suggest that they do not share the same biological function. Kallikrein-like proteinases also have restricted specificities that are probably related to their extended substrate binding site. This makes them good candidates for processing inactive protein or peptide precursors into biologically active peptides. A general approach to identifying the putative biological substrates of individual proteinases based on analysis of the specific cleavage of synthetic and natural peptide substrates by kallikrein-related proteinases is described.

Amino Acid Sequence↗
PubMed1992

Is there a place for radiation therapy in the management of hepatoblastomas and hepatocellular carcinomas in children?

From May 1978 to August 1988, 15 children with a primary malignant liver tumor received radiation therapy as part of their management at the Institut Gustave-Roussy. Age ranged from 4 months to 13 years. The male to female ratio was 1.5. Eleven patients had a histologically proven hepatoblastoma, two a hepatocellular carcinoma, and histology was not documented in two. Resection of the primary liver tumor was performed in nine cases, and all patients also received sequential chemotherapy, generally preoperative and alternating vincristine, doxorubicin, cyclophosphamide with vincristine, cyclophosphamide, and cis-platinum. Radiotherapy was performed postoperatively in eight incompletely resected patients. Six of eight are alive and free of disease 4-83 months following treatment (median 39 months) and 11-98 months since diagnosis (median 45 months). All but one were treated to limited fields to a total dose of 25-45 Gy (median 40 Gy). One patient became resectable by a combination of 24 Gy to the whole liver and concomitant 5FU and Cis-Platinum and remains with no evidence of disease 68 months following radiation therapy. Of four unresectable primaries, only one was controlled by radiotherapy. Neither of two children with pulmonary metastases were controlled by whole lung irradiation to a dose of 18 and 20 Gy, respectively, and one still remains stable 41 months after resection of a residual metastatic nodule. Neither of two hepatocellular carcinomas were controlled by doses up to 40 Gy. This small series suggests that in hepatoblastoma, radiotherapy to a total of 25-45 Gy fractionated doses, combined with chemotherapy, can play a role in selected inoperable children and also in those with minimal postoperative residues below 2 cm. It also indicates that in hepatocellular carcinoma, radiotherapy is ineffective in this dose-range.

Adolescent↗
PubMed1992

Cystatin mimicry by synthetic peptides.

Synthetic peptides which tentatively mimic the cystatin inhibitory surface were used to study the mechanism of inhibition of cysteine proteinases by their natural inhibitors. The inhibitory properties of these peptides depend mainly on the presence of the QxVxG consensus sequence. N and C-terminal peptide derivatives bearing large hydrophobic groups showed dramatically improved inhibition. Molecular dynamic studies after energy minimization showed that the non covalent interaction between these hydrophobic groups induced the formation of a loop structure which probably favours inhibition. Antibodies were raised against one of these peptides, which recognized kininogens in the serum of all mammal species tested, but not cystatins from family two.

Animals↗
PubMed1991

Discrimination between rat thiostatin (T-kininogen) and one of its cystatin-like inhibitory fragments by a monoclonal antibody, and localization of the epitope.

A monoclonal antibody (mAb D3) raised against rat thiostatin (T-kininogen) strongly interacted with a fragment, identified as cystatin-like domain 3, which inhibits cysteine proteinases but did not recognize intact, native thiostatin. The antigen-antibody reaction requires cleavage of the single peptide chain of thiostatin in its inter-domain 2-3 region. This mAb can also differentiate between the two molecular varieties of thiostatin, reacting only with immobilized domain 3 from T1 thiostatin, which differs from the T2 variety by only 10 out of 125 residues. mAb D3 did not react with an N-terminally truncated domain 3 of T1 thiostatin prepared by submaxillary gland kallikrein k10 proteolysis. This suggests that the epitope, or an essential part of it, is located on a stretch of 12 residues at the N-terminal of the T1 thiostatin domain 3. This sequence in T1 thiostatin differs from that in T2 thiostatin by four amino acids, two of which are arginyl residues in T1. Chemical modification of these residues located at positions 246 and 250 decreased the reactivity of T1 domain 3 towards the antibody, suggesting that at least one of them is a critical residue of the epitope. Arginine 246 is part of a small disulfide loop between cysteines 245 and 248 which is also necessary for antibody recognition. This antibody does not change the inhibitory properties of purified domain 3 towards papain or rat liver cathepsin L, indicating that the N-terminal part of domain 3 is not involved in inhibition. mAb D3 was used to demonstrate the presence of inhibitory thiostatin fragments in ascites fluid but not in plasma from normal or turpentine-injected rats.

Amino Acid Sequence↗
PubMed1990

Nutritionally-induced elevation of serum proteinase inhibitors and reduced 3-methylhistidine excretion in the rat.

One group of growing rats was fed ad libitum a low protein and energy diet (PER). A second group was fed a low protein diet (PR). Both these groups showed a gain in weight below that of the control group. A third group was fed a very low protein and energy diet (VPER). A weight gain could also be observed in this group but this gain was lower than those observed in the first two groups. A fourth group that was on a very low protein diet (VPR) gained almost no weight. After 6 weeks a significant reduction in 3-methylhistidine excretion in urine was observed in all the experimental animals with lowest values found in the VPER and VPR groups. Total serum protein levels declined to a certain extent because of the protein and energy restrictions but albumin and transferrin remained largely unaffected. Significantly lower serum concentrations were found only in the VPR group. The rat serum proteinase inhibitors alpha 1-macroglobulin and alpha 1-inhibitor3 decreased when protein and energy were restricted and alpha 1-proteinase inhibitor decreased only in the VPER and VPR groups. alpha 2-macroglobulin and alpha 1-cysteine proteinase inhibitor concentrations increased considerably in the serum of the experimental groups. The results are discussed in relation to the probable role of the latter two inhibitors in the adaptation process when protein and energy were restricted and compared to similar observations recorded in man.

Animals↗
PubMed1979

Interactions in vitro and in vivo between rat serum protease inhibitors and anodal and cathodal rat trypsin and chymotrypsin.

Reaction mixtures of increasing amounts of the pancreatic homologous proteases, anodal and cathodal chymotrypsin and trypsin, respectively, and normal rat serum were analyzed by immunoelectrophoretic methods in order to determine their distribution on serum protease inhibitors. This paper concerns three proteins occurring in normal serum and capable of binding protease viz. alpha1-macroglobulin, alpha1-antitrypsin and alpha1-inhibitor 3. The distribution of the enzymes among these protease inhibitors differed significantly from one protease to another. The distribution of the proteases among the serum protease inhibitors following intravenous injection of 125I-labelled proteases corresponded to that in vitro. Complexes formed with alpha1-macroglobulin and alpha1-inhibitor 3 were quickly eliminated irrespective of the enzyme species used, whereas those formed with alpha1-antitrypsin persisted much longer in the circulation.

Animals↗
PubMed1979

[Congenital anorectal stenosis (8 cases) (author's transl)].

The authors present a series of 8 cases of congenital anorectal stenosis treated recently, with a follow up of 1 to 7 years. The finding of 3 poor results from the standpoint of anal continence leads to a discussion of the general prognosis of this malformation classically considered as being benign.

Anal Canal↗
PubMed1979

[Ovarian cysts and tumors in neonates, infants and children (author's transl)].

Twenty-six girls, aged from 0 to 15 years, were operated, upon ovarian cysts and tumors from 1952 to 1977. Before the age of one year, 11 non-neoplastic cysts and 2 benign tumors were observed. After the age of one, 1 non-neoplastic cyst and 12 tumors: 8 germ-cell tumors, 3 tumors of specialized gonadal stroma, and one epithelial tumor. Three germ-cell tumors were malignant (1 girl dead of disease, 2 alive at 2 and 1 1/2 years). All three gonadal stromal tumors are benign (with a follow-up of 3 months, 4 and 20 years). Epidemiology, pathology prognosis and management of these tumors are discussed according the recent literature.

Adolescent↗