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Biomedical subjects

P Jacques

Publications and source records attributed to P Jacques.

88 records · Page 5Linked to original sources
PubMed1976

[Incorporation of labeled precursors in glycosaminoglycans of the media-intima of the arterial wall].

The enzymes involved in glycosaminoglycans biosynthesis are characterized in homogenates of aortic media-intima. Incorporation of hexosamine from uridine nucleotide precursor was done into the saccharide chains of glycosaminoglycans. Labelling of aortic glycosaminoglycans by 35S-precursors is performed in our fractions; the results obtained demonstrate the uptake of 35S-sulfate from its corresponding active nucleotide sulfate ; highest sulfation is obtained for the post-microsomal supernatant. Following incorporation of 35S-sulfate or 14C-radio-activity into the different glycosaminoglycans, the largest percent uptake is obtained for heparan sulfate and the lowest for chondroitin sulfate.

Animals↗
PubMed1965

Studies on bone enzymes. The assay of acid hydrolases and other enzymes in bone tissue.

1. Nine acid hydrolases, cytochrome oxidase, alkaline phenylphosphatase and catalase were demonstrated in 0.25m-sucrose homogenates of newborn-rat calvaria. The acid hydrolases were: acid phenylphosphatase, acid beta-glycerophosphatase, beta-glucuronidase, beta-N-acetylglucosaminidase (beta-N-acetylaminodeoxyglucosidase), acid ribonuclease and acid deoxyribonuclease, showing optimum activity at about pH5; cathepsin, beta-galactosidase and hyaluronidase, with optimum activity at about pH3.6. 2. The main kinetic characters of these enzymes have been studied and methods for their quantitative assay have been worked out. The activities present in bone are given and compared with those found in liver. 3. Acid-phosphatase activity was assayed with phenyl phosphate and beta-glycerophosphate as substrates: activities with these two substrates appeared to be due to two different enzymes. Acid phenylphosphatase is particularly labile and is readily inactivated by various physical or chemical agents.

Journal Article↗
PubMed1965

Studies on bone enzymes. Distribution of acid hydrolases, alkaline phenylphosphatase, cytochrome oxidase and catalase in subcellular fraction of bone tissue homogenates.

1. When bone homogenates were fractionated according to the scheme developed for liver by de Duve, Pressman, Gianetto, Wattiaux & Appelmans (1955), all the enzymes assayed except cytochrome oxidase were found to occur partly in soluble and partly in particulate fractions. Among the particle-bound enzymes, the highest specific activity was found in the heavy-mitochondrial fraction for cytochrome oxidase, in the microsomal fraction for alkaline phenylphosphatase and in the light-mitochondrial fraction for eight acid hydrolases and for catalase. 2. Combined heavy-mitochondrial and light-mitochondrial fractions were subfractionated by isopycnic centrifugation in density gradients of sucrose or glycogen. In the various systems tried, cytochrome oxidase showed a relatively narrow distribution range with a sharp peak; the acid hydrolases and catalase showed flat and irregular distribution patterns, differing slightly in shape from one enzyme to the other. However, it was not possible to achieve a marked separation between the various enzymes under study. 3. It is concluded from these results that the acid hydrolases belong to special cytoplasmic particles, probably lysosomes, and that these particles are physically and enzymically heterogeneous. Catalase appears to be non-mitochondrial and could also belong to the lysosomes; but the possibility of an association with another type of particle must be kept in mind in view of what is known of liver catalase. Alkaline phenylphosphatase is largely attached to microsomal elements.

Journal Article↗
PubMedDate not supplied

Comparative photoaffinity labeling study between azidophenyl, difluoroazidophenyl, and tetrafluoroazidophenyl derivatives for the GABA-gated chloride channels.

Syntheses of 2-aryl-substituted photoactivatable derivatives of 5-tert-butyl-1,3-dithiane and their oxidized bis-sulfone are described. The 4-azidoaryl and the 3,5-difluoro-4-azidoaryl groups were chosen as photosensitive moieties. Azidoaryl derivatives 3 and 13 were synthesized by diazotization and azidation of their corresponding arylamine precursors. The o-difluoroazidophenyl derivatives 2 and 9 were synthesized by transformation of the o-difluoro-substituted lithiophenyl into the corresponding azido derivative. The reversible binding properties of the photosensitive probes were established on bovine cortex P2 membranes by displacement of [3H]-1-phenyl-4-tert-butyl- 2,6,7-trioxabicyclo[2.2.2]-octane ([3H]TBOB), a specific ligand for the channel blocker binding site. The 2-(3',5'-difluro-4'-azidophenyl)-5-tert-butyl- 1,3-dithianebis-sulfone, compound 2, exhibited the best Ki of about 11 nM, compared to Kis of 180 and 570 nM, respectively, for probes 1 (azidotetrafluorophenyl analogue) and compared to Kis of 180 and 570 nM, respectively, for probes 1 (azidotetrafluorophenyl analogue) and 3 (azidphenyl analogue). On irradiation, probe 2 (0.6 microM) produced 18% irreversible loss of TBOB binding sites in brain membranes while probe 3 did not produce any photoinactivation. The loss observed with 2 was fully protectable by TBOB, demonstrating the specificity of the photochemical inactivation by compound 2 for the convulsant site of the GABAA receptor. These results, when compared to the photoaffinity labeling results obtained with the tetrafluorinated probe 1 (25% selective irreversible photochemical inactivation), establish a hierarchy between fluorinated and nonfluorinated arylazido probes and strengthen the potential of the newly described difluorinated probe 2, combining high affinity and good labeling efficacy.

Affinity Labels↗
PubMedDate not supplied

Structure and characterization of isopyoverdin from Pseudomonas putida BTP1 and its relation to the biogenetic pathway leading to pyoverdins.

Pyoverdin type siderophores produced by six fluorescent Pseudomonas strains isolated from different rhizospheres were purified and characterized. The purified ferri-pyoverdins were tested for their ability to promote the growth of other strains grown under iron deficiency conditions. Only the one obtained from Pseudomonas putida BTP1 did not act as a growth promoter. The structure of the BTP1 siderophore was elucidated by spectroscopic methods and degradation studies. It turned out that it contains a chromophore which differs from the one typical for pyoverdins insofar as it carries the carboxyl group in 3- rather than in 1-position ((3S)-5-amino-1,2-dihydro-8,9-dihydroxy-3H-pyrimido[1,2a]quinoline-3- carboxylic acid). The amino group of the chromophore is substituted with the 5-carboxyl group of L-glutamic acid and its carboxyl group with the N-terminus of the peptide L-Asp-L-Ala-L-Asp-D-N5-Ac-N5-OH-Orn-L-Ser-L-c-N5-OH-Orn. This isopyoverdin fits into the biogenetic scheme which postulates ferribactins as the precursors of pyoverdins.

Amino Acid Sequence↗
PubMedDate not supplied

Evaluation of the microtensile bond strength of composite resin restoration in dentin prepared with different sizes of aluminum oxide particles, using the air abrasion system.

AIM: The purpose of this in vitro study was to evaluate the influence of the abrasive technique on the microtensile bond strength of composite resin restorations. In addition, any differences in the microtensile bond strength were observed when different aluminum oxide particle sizes were used. METHODS: Flat coronal dentin surfaces were randomly distributed into 3 groups, according to surface treatment: Group A27 Air-abraded dentin with 27 microm aluminum oxide particles; Group A50-Air-abraded dentin with 50 microm aluminum oxide particles; Group HS cut dentin with a #1013 diamond bur in high-speed rotary instrument. After the bonding procedure (Single Bond/Z100), the teeth were stored in distilled water at 37 masculineC for 48 h prior to sectioning. Then, each bonded tooth was longitudinally sectioned producing sticks with a cross-sectional area of 0.81 mm2. The tensile load was applied at a crosshead speed of 0.5 mm/min, until the stick fractured. The data were analyzed by one-way ANOVA and post hoc multiple comparisons using Tukey's test. RESULTS: No difference was observed in composite bond strength when 27 and 50 microm aluminum oxide particles were used for dentin surface preparation using an air abrasion system. However, air-abraded dentin, using 27 microm aluminum oxide particles, demonstrated a higher bond strength when compared to dentin prepared by the conventional method (bur in high-speed). CONCLUSIONS: The air-abraded dentin, using 27 microm alumina powder, demonstrated higher composite bond strength when compared to bur-cut dentin, raising the possibility that this method may increase restoration longevity.

Acrylic Resins↗
PubMedDate not supplied

Spontaneous exoneration of a colonic lipoma.

Colonic lipoma is a rare tumor. This tumor is usually asymptomatic. We report the case of a patient who complained of abdominal pain. Symptoms disappeared after spontaneous exoneration of a colonic lipoma.

Colonic Neoplasms↗