Effect of taurine on wound healing

Summary Taurine which has antioxidant effects is also known to have effects on cell proliferation, inflammation and collagenogenesis. The aim of this study was to investigate the effect of taurine on incisional skin wounds.The mice incised on the dorsal area were divided into control and experimental groups. Saline was injected intraperitoneally to half of the animals in the control group and locally applied to the other half. Fifty mM taurine solution was given intraperitoneally to the first half of the experimental animals and locally to the second half of the experimental group.After four days of treatment, malondialdehyde (MDA) and histamine levels as well as the tensile strength of the wound tissue were measured. Structural alterations in epidermis and dermis were histologically evaluated.The locally administreated taurine significantly increased wound tensile strength by decreasing the MDA and histamine levels and prevented the degranulation of the mast cells. These observations suggest that taurine may be useful on wound healing.     

Effect of anoxia and reoxygenation on antioxidant enzyme activities in immortalized brain endothelial cells

Summary The effects of anoxia and reoxygenation on major antioxidant enzyme activities were investigatedin vitro in immortalized rat brain endothelial cells (RBE₄ cells). A sublethal anoxic period of 12 h was assessed for RBE₄ cells using the neutral red uptake test. Anoxia markedly influenced the specific activity of catalase and superoxide dismutase, with no major effect on glutathione peroxidase or glutathione reductase. After 24 h postanoxia, the superoxide dismutase activity modulated by the presence or absence of oxygen returned to control value. Damage and recovery of RBE₄ immortalized rat brain endothelial cells in culture after exposure to free radicals and other oxygen-derived species provides a usefulin vitro model to study anoxia-reoxygenation trauma at the cellular level.     

Repetitive DNA sequences located in the central region of the human mdr1 (multidrug resistance) gene may account for a gene fusion event during its evolution

The mdr1 gene, first member of the human multidrug-resistance gene family, is a major gene involved in cellular resistance to several drugs used in anticancer chemotherapy. Its product, the drug-excreting P-glycoprotein, shows a bipartite structure formed by two similar adjacent halves. According to one hypothesis, the fusion of two related ancestral genes during evolution could have resulted in this structure. The DNA sequence analysis of the introns located in the region connecting the two halves of the human mdr1 gene revealed a highly conserved poly(CA) · poly (TG) sequence in intron 15 and repeated sequences of the Alu family in introns 14 and 17. These repeated sequences most likely represent molecular fossils of ancient DNA elements which were involved in such a recombination event. Correspondence to: M. Pauly     

Operational patterns affecting lactic acid production in ultrafiltration cell recycle bioreactor

Lactic acid production with cell recycling on an ultrafiltration tubular membrane reactor was studied; higher lactic acid concentrations as well as productivities were obtained under long-term fermentations compared with other high cell density systems. Different operational conditions, namely dilution rates and start-up modes, were assessed. Performances were very different at the three different dilution rates tested (D = 0.20 h(-1), D = 0.40 h(-1), or D = 0.58 h(-1)). The different behaviours are discussed and factors responsible for them are presented. The best way to operate for lactic acid production is chosen, the dilution rate of D = 0.40 h(-1) being the one providing the best overall performance. On the other hand, results show that of the two start-up modes tested, continuous start (membrane open) permits higher permeabilities throughout the operational runs than batch start (membrane closed). Operational stability was found to be directly associated with membranes that work at "steady state," the membrane permeability being kept around 15 L/m(2) h. Optimized cell bleed can improve time of operation if such membrane permeability can be maintained for a longer time. A comparison of results with those obtained in other lactic acid production systems is presented; such comparison shows that this tubular ultrafiltration membrane cell recycle reactor presents three important advantages: (1) concomitant lactic acid concentrations and productivities; (2) long periods of operation at reasonable permeabilities; and (3) good mechanical stability permitting the use of steam sterilization. (c) 1995 John Wiley & Sons, Inc.     

Changes in the subcellular localization of replication initiation proteins and cell cycle proteins during G1- to S-phase transition in mammalian cells

DNA replication in eukaryotic cells is restricted to the S-phase of the cell cycle. In a cell-free replication model system, using SV40 origin-containing DNA, extracts from G1 cells are inefficient in supporting DNA replication. We have undertaken a detailed analysis of the subcellular localization of replication proteins and cell cycle regulators to determine when these proteins are present in the nucleus and therefore available for DNA replication. Cyclin A and cdk2 have been implicated in regulating DNA replication, and may be responsible for activating components of the DNA replication mitiation complex on entry into S-phase. G1 cell extracts used for in vitro replication contain the replication proteins RPA (the eukaryotic single-stranded DNA binding protein) and DNA polymerase as well as cdk2, but lack cyclin A. On localizing these components in G1 cells we find that both RPA and DNA polymerase are present as nuclear proteins, while cdk2 is primarily cytoplasmic and there is no detectable cyclin A. An apparent change in the distribution of these proteins occurs as the cell enters S-phase. Cyclin A becomes abundant and both cyclin A and cdk2 become localized to the nucleus in S-phase. In contrast, the RPA-34 and RPA-70 subunits of RPA, which are already nuclear, undergo a transition from the uniform nuclear distribution observed during G1, and now display a distinct punctate nuclear pattern. The initiation of DNA replication therefore most likely occurs by modification and activation of these replication initiation proteins rather than by their recruitment to the nuclear compartment.     

Molecular Diversity and Evolution of bla TEM Genes Encoding β-Lactamases Resistant to Clavulanic Acid in Clinical E. coli

The molecular diversity of inhibitor-resistant TEM (IRT) enzymes was explored using a strategy which involved DNA amplification by polymerase chain reaction (PCR), analysis of restriction fragment length polymorphism (RFLP), and direct nucleotide sequencing. The study of plasmid-borne genes from 27 strains, resistant to amoxicillin and β-lactamase-inhibitor combinations, identified mutations resulting in amino acid change at positions 69, 244, 275, and 276 known to be associated with the IRT phenotype and a mutation at nucleotide position 162 in the promoter region. These mutations were found to lie on two different gene sequences, described here as ``TEM-1B like' and ``TEM-2 like' restriction linkage groups. Further analysis, of nucleotide sequences of promoter and coding regions of the β-lactamases, confirmed that a given mutation causing IRT phenotype could be associated with two different gene sequence frameworks and two different causal mutations could lie on identical gene sequence framework. These data argue in favor of convergent phenotypic evolution of IRT enzymes under the selective pressure imposed by the intensive clinical use of β-lactam–β-lactamase inhibitor combinations. Received: 18 March 1996 / Accepted: 15 July 1996     

Subregional mapping of the human gonadotropin-releasing hormone receptor (GnRH-R) gene to 4q between the markers D4S392 and D4S409

We have isolated nine yeast artificial chromosomes (YACs) containing the gene that encodes the human gonadotropin-releasing hormone receptor (GnRH-R) gene by screening the YAC library of the Centre d'Etude du Polymorphisme Humain (Hôpital Saint-Louis, Paris, France) by the use of the polymerase chain reaction. We defined the location of the GnRH-R gene relative to 4q microsatellite markers D4S392 and D4S409. The genetic positions of these markers on chromosome 4 are 76 and 77 cM, respectively. This location was further established by chromosomal in situ hybridization.     

Excess of deletions of maternal origin in the DiGeorge/Velo-cardio-facial syndromes. A study of 22 new patients and review of the literature

We have determined the parental origin of the deleted chromosome 22 in 29 cases of DiGeorge syndrome (DGS) using a CA-repeat mapping within the commonly deleted region, and in one other case by using a chromosome 22 short arm heteromorphism. The CA-repeat was informative in 21 out of 29 families studied and the deleted chromosome was of maternal origin in 16 cases (72%). When these data are pooled with recent results from the literature, 24 de novo DGS, velo-cardio-facial syndrome (VCFS) and isolated conotruncal cardiac disease deletions are found to be of maternal origin and 8 of paternal origin, yielding a ² of 8 with a probability level lower than 0.01. These data, and review of the literature on familial DGS/VCFS and isolated conotruncal cardiopathies suggest that there is a strong tendency for the 22q11.2 deletions to be of maternal origin.     

Entrapment of l-tryptophan producing Escherichia coli in different matrices: activity of immobilized cells

Cells of Escherichia coli induced for l-tryptophan synthase [l-serine hydro-lyase (adding indole-glycerol-phosphate), EC 4.2.1.20] have been assayed in DMF and DMSO aqueous solvents as reaction medium. Up to 20% DMF/water, cells retained 90% of their tryptophan synthase activity. Concentrations of 20 mM indole, which did not inhibit this reactivity, could be reached with 5% DMF/water. Four matrices were compared for cell immobilization: polyacrylamide, foam particles of bovine seum albumin, alginate and κ-carrageenan. The best activity was retained with the latter matrix, and the preparations thus obtained allowed high productivity of l-tryptophan. Various systems of production of l-tryptophan with κ-carrageenan and DMF/water were studied.