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C Boon

Publications and source records attributed to C Boon.

10 recordsLinked to original sources
PubMed2002

A pharmacokinetic comparison of the modified release capsule and a plain tablet formulation of mebeverine.

This study was conducted to compare the pharmacokinetic properties of the modified release 200 mg capsule of mebeverine and the plain 135 mg tablet of mebeverine after single and multiple doses in 12 healthy subjects in a randomised, crossover design. Single doses were given on days 1 and 7 and multiple doses (200 mg b.i.d. for the capsule and 135 mg t.i.d. for the tablet) on days 2-6 of the study. The 200 mg modified release capsule of mebeverine has extended release properties, as indicated by a lower Cmax, a later tmax and a longer elimination half-life than the plain tablet, while the bioavailability is optimal. No significant accumulation occurs after multiple doses of either formulation. The twice-daily dosage regimen of the 200 mg modified release capsule is a good alternative to the three times daily dosage regimen of the 135 mg plain tablet, because the reduced daily intake is likely to benefit patient compliance.

Adult↗
PubMed2001

Proteins of Mycobacterium bovis BCG induced in the Wayne dormancy model.

Oxygen starvation triggers the shiftdown of the obligate aerobe Mycobacterium bovis BCG to a state of dormancy. Two-dimensional electrophoresis showed a drastic up-regulation of the alpha-crystallin homolog, the putative response regulator Rv3133c, and the two conserved hypothetical proteins Rv2623 and Rv2626c in dormant bacilli.

Aerobiosis↗
PubMed2000

Initiation of DNA fragmentation during apoptosis induces phosphorylation of H2AX histone at serine 139.

Histone H2AX is a ubiquitous member of the H2A histone family that differs from the other H2A histones by the presence of an evolutionarily conserved C-terminal motif, -KKATQASQEY. The serine residue in this motif becomes rapidly phosphorylated in cells and animals when DNA double-stranded breaks are introduced into their chromatin by various physical and chemical means. In the present communication we show that this phosphorylated form of H2AX, referred to as gamma-H2AX, appears during apoptosis concurrently with the initial appearance of high molecular weight DNA fragments. gamma-H2AX forms before the appearance of internucleosomal DNA fragments and the externalization of phosphatidylserine to the outer membrane leaflet. gamma-H2AX formation is inhibited by N-benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone and the inhibitor of caspase-activated DNase, and it is induced when DNase I and restriction enzymes are introduced into cells, suggesting that any apoptotic endonuclease is sufficient to induce gamma-H2AX formation. These results indicate that gamma-H2AX formation is an early chromatin modification following initiation of DNA fragmentation during apoptosis.

Apoptosis↗
PubMed1999

Megabase chromatin domains involved in DNA double-strand breaks in vivo.

The loss of chromosomal integrity from DNA double-strand breaks introduced into mammalian cells by ionizing radiation results in the specific phosphorylation of histone H2AX on serine residue 139, yielding a specific modified form named gamma-H2AX. An antibody prepared to the unique region of human gamma-H2AX shows that H2AX homologues are phosphorylated not only in irradiated mammalian cells but also in irradiated cells from other species, including Xenopus laevis, Drosophila melanogaster, and Saccharomyces cerevisiae. The antibody reveals that gamma-H2AX appears as discrete nuclear foci within 1 min after exposure of cells to ionizing radiation. The numbers of these foci are comparable to the numbers of induced DNA double-strand breaks. When DNA double-strand breaks are introduced into specific partial nuclear volumes of cells by means of a pulsed microbeam laser, gamma-H2AX foci form at these sites. In mitotic cells from cultures exposed to nonlethal amounts of ionizing radiation, gamma-H2AX foci form band-like structures on chromosome arms and on the end of broken arms. These results offer direct visual confirmation that gamma-H2AX forms en masse at chromosomal sites of DNA double-strand breaks. The results further suggest the possible existence of units of higher order chromatin structure involved in monitoring DNA integrity.

Animals↗
PubMed1996

Partial trisomy 10 mosaicism with cutaneous manifestations: report of a case and review of the literature.

A female infant with partial trisomy 10 mosaicism and hypomelanosis of Ito is presented. Features include a prominent forehead, hypertelorism, large dysplastic ears, prominent nasal root, a cleft lip and alveolar ridge, bilateral metatarsus adductus, and streaks and whorls of hypopigmented skin. The skin findings were diagnostic for hypomelanosis of Ito. A peripheral blood karyotype was normal. Fibroblasts from a junctional skin biopsy revealed mosaicism for partial trisomy of chromosome 10 [46, XX/47, XX, +del(10) (q11.2q23.2)]. The physical findings of this patient are compared to five published cases of complete trisomy 10 mosaicism and 94 cases of isolated trisomy 10p and trisomy 10q.

Abnormalities, Multiple↗
PubMed1994

Rheumatoid arthritis is not associated with prior tonsillectomy or appendectomy.

To re-evaluate a reported association of rheumatoid arthritis (RA) with antecendent tonsillectomy or appendectomy, questionnaires were sent by post to 3673 patients who had been diagnosed as having either RA or osteoarthrosis (OA). Of those who responded 1524 were RA and 1194 OA patients. No significant differences were found between these groups with regard to the frequency of prior lymphoid surgery. This was also the case when the RA group was replaced by its rheumatoid factor (Rf) positive or Rf negative subgroup. A separate analysis of a subgroup consisting of 671 Rf positive RA patients for whom OA control subjects matched for sex and year of birth were available again showed no statistical differences in frequencies of tonsillectomy and appendectomy. Neither did partitioning the group according to the age at which lymphoid surgery was performed bring any association with an increased occurrence of RA to light. We therefore reject the hypothesis that RA is associated with antecedent tonsillectomy or appendectomy.

Adolescent↗
PubMed1993

Elongation factors in protein synthesis.

Recent discoveries of elongation factor-related proteins have considerably complicated the simple textbook scheme of the peptide chain elongation cycle. During growth and differentiation the cycle may be regulated not only by factor modification but also factor replacement. In addition, rare tRNAs may have their own rare factor proteins. A special case is the acquisition of resistance by bacteria to elongation factor-directed antibiotics. Pertinent data from the literature and our own work with Escherichia coli and Streptomyces are discussed. The GTP-binding domain of EF-Tu has been studied extensively, but little molecular detail is available on the interactions with its other ligands or effectors, or on the way they are affected by the GTPase switch signal. A growing number of EF-Tu mutants obtained by ourselves and others are helping us in testing current ideas. We have found a synergistic effect between EF-Tu and EF-G in their uncoupled GTPase reactions on empty ribosomes. Only the EF-G reaction is perturbed by fluoroaluminates.

Animals↗
PubMedDate not supplied

Inducibility of the Streptomyces traRts107-Ptra expression cassette in Mycobacterium smegmatis.

An inducible Streptomyces expression cassette utilising the Ptra promoter and a temperature-sensitive allele of the TraR repressor from S. nigrifaciens plasmid pSN22 was tested in Mycobacterium smegmatis. Using reporter assays and Northern blot analysis, a marked increase of Ptra-directed transcription was observed upon a temperature shift from 28 to 37 degrees C. These results show that the S. nigrifaciens promoter-repressor cassette is functional in M. smegmatis. However, comparison of the level of induced Ptra-directed transcription with the level of transcription directed by the strong mycobacterial promoter Phsp60 indicated that the relative strength of the Ptra promoter was low. Considering the severe limitation of inducible expression systems for mycobacteria, this Streptomyces cassette might be a useful starting point for the development of a compact and fully portable inducible mycobacterial expression cassette.

Bacterial Proteins↗