Search Results - (Author, Cooperation:M. Willem)

2015-09-01

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

article

1985

Projektstudium

Pedagogische studiën, Bd. 62 (1985) H. 3, S. 139-150, 0165-0645

facet.language.dut, facet.language.eng

Literaturangaben 23

2018-06-16

The American Society for Biochemistry and Molecular Biology (ASBMB)

0021-9258

1083-351X

Biology

Chemistry and Pharmacology

2018-11-11

American Chemical Society (ACS)

Chemistry and Pharmacology

2018-05-10

Nature Publishing Group (NPG)

2158-3188

Medicine

1523-5378

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Background.Omeprazole enhances the efficacy of bismuth-based triple therapy. It is unknown whether the same is true for other proton pump inhibitors. Lansoprazole has superior anti-Helicobacter activity in vitro and possibly also in vivo; therefore we investigated quadruple therapy with lansoprazole. Materials and Methods.In two studies performed in separate hospitals, a total of 67 Helicobacter pylori–positive patients were treated with 7-day quadruple therapy (lansoprazole, colloidal bismuth subcitrate, tetracycline, and metronidazole) after 3 days of lansoprazole pretreatment. Testing for cure was done by endoscopy in study 1 and by breath test in study 2. Results.Cure rates per protocol were 31 of 31 (100%) in study 1 and 30 of 32 (94%) in study 2. Intention-to-treat cure rates were 31 of 35 (89%) in study 1 and 30 of 32 (94%) in study 2. Cured overall were 32 of 34 with a metronidazole sensitive strain and 3 of 3 with a metronidazole-resistant strain. Data on side effects were collected from 51 patients. Twelve (21%) had no side effects, 27 (53%) had mild side effects, 10 (20%) had moderate side effects, but only 2 (4%) had severe side effects. Side effects, never were the reason that a patient stopped taking the medication. Conclusions.The results with lansoprazole-quadruple therapy are comparable to the historic control group treated with omeprazole-quadruple therapy. The cure rate is very high, and although mild to moderate side effects occured in many patients, everybody finished the treatment regime.

Electronic Resource

1471-0528

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Objective The traditional treatment of ectopic pregnancy is salpingectomy, while conservative surgery aims to save the function of the uterine tube. This study compares the effectiveness and the economic costs of salpingectomy and conservative tubal surgery in women with a tubal pregnancy.Methods Salpingectomy and conservative tubal surgery were compared economically, based on a combined retrospective and prospective cohort study and a review of the literature. A model was developed in which conservative surgery and salpingectomy with in vitro fertilisation and embryo-transfer (IVF-ET) were compared with salpingectomy alone.Participants One hundred and fifteen consecutive women treated laparoscopically for tubal pregnancy.Main outcome measures Complete removal of the tubal pregnancy; subsequent intrauterine pregnancy rate; economic analysis.Results Tubal pregnancy was always treated successfully by both methods, sometimes with additional treatment for persistent trophoblast. In the short term costs per patient were £1554 (95% confidence interval [CI] £1501–£1656) for salpingectomy and £1787 (95% CI £1683–£1930) for conservative surgery. The mean difference between costs of salpingectomy and costs of conservative surgery was £233 (95% CI £80–£371). Concerning subsequent intrauterine pregnancy, conservative surgery is slightly more effective than salpingectomy but is more expensive. Costs per subsequent intrauterine pregnancy are £4063. If IVF-ET is performed in all women who are not pregnant within three years after salpingectomy, costs per subsequent intrauterine pregnancy are £15,629.Conclusions Salpingectomy is the treatment of choice in women not desiring future pregnancy. Salpingectomy seems less effective than conservative surgery when future pregnancy is desired, but is less costly. Conservative surgery seems more cost effective than salpingectomy with additional IVF-ET.

Electronic Resource

1600-065X

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Summary: In addition lo chemotherapy and irradiation, in the context of allogeneic stem cell transplantation (SCT), the donor cell-mediated anti-leukemic effect can lead to sustained complete remissions, also in cases of a large tumor load. This phenomenon appears to be an immunologically mediated response, possibly due to various effector cell populations. Cytotoxic T-lymphocyte (CTL) responses against minor histocompatibility antigens with restricted tissue distribution, in particular restricted to some or all hematopoietic cells, may be highly efficient in inducing and-leukemic responses for adoptive immunotherapy Specific CTL responses against leukemia-associated antigens may be generated using leukemic cells modified to co-express costimulatory molecules identical to professional antigens may be used in the context of allogeneic tells Donor derived T cell recognizing such antigens may be used in the context of allogeneic SCT to induce complete and sustained remissions, also in patients with leukemia refractory to chemotherapy. In these to circumstances, the primary objective of allogeneic SCT may be not to diminish the number of malignant cells by the chemotherapy and irradiation as part of the conditioning regimen, but to allow immunotherapy against leukemic cells using donor lymphocyte populations.

Electronic Resource

1365-2958

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Medicine

Biosynthesis of gelatinase, a virulence factor of Enterococcus faecalis, was found to be regulated in a cell density-dependent fashion in which its production is active in late log to early stationary phase. Addition of early stationary phase culture filtrate to medium shifted the onset of gelatinase production to that of mid-log phase, suggesting that E. faecalis secretes a gelatinase biosynthesis-activating pheromone (GBAP). GBAP was isolated from culture supernatant of E. faecalis OG1S-P. Structural analysis suggested GBAP to be an 11-residue cyclic peptide containing a lactone structure, in which the α-carboxyl group of the C-terminal amino acid is linked to a hydroxyl group of the serine of the third residue. A synthetic peptide possessing the deduced structure showed GBAP activity at nanomolar concentrations as did natural GBAP. Database searches revealed that GBAP corresponds to a C-terminal part of a 242-residue FsrB protein. Northern analysis showed that GBAP slowly induces the transcription of two operons, fsrB-fsrC encoding FsrB and a putative histidine kinase FsrC and gelE-sprE encoding gelatinase GelE and serine protease SprE. Strains with an insertion mutation in either fsrC or a putative response regulator gene fsrA failed to respond to GBAP, suggesting that the GBAP signal is transduced by a two-component regulatory system.

Electronic Resource

1365-2958

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Medicine

Lantibiotics form a family of highly modified peptides which are secreted by several Gram-positive bacteria. They exhibit antimicrobial activity, mainly against other Gram-positive bacteria, by forming pores in the cellular membrane. These antimicrobial peptides are ribosomally synthesized and contain leader peptides which do not show the characteristics of signal sequences. Several amino acid residues of the precursor lantibiotic are enzymatically modified, whereafter secretion and processing of the leader peptide takes place, yielding the active antimicrobial substance. For several lantibiotics the gene clusters encoding biosynthetic enzymes, translocator proteins, self-protection proteins, processing enzymes and regulatory proteins have been identified. This MicroReview describes the current knowledge about the biosynthetic, immunity and regulatory processes leading to lantibiotic production. Most of the attention is focused on the lantibiotic nisin, which is produced by the food-grade bacterium Lactococcus lactis and is widely used as a preservative in the food industry.

Electronic Resource

1365-2958

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Medicine

The Lactococcus lactis ccpA gene, encoding the global regulatory protein CcpA, was identified and characterized. Northern blot and primer extension analyses showed that the L. lactis ccpA gene is constitutively transcribed from a promoter that does not contain a cre sequence. Inactivation of the ccpA gene resulted in a twofold reduction in the growth rate compared with the wild type on glucose, sucrose and fructose, while growth on galactose was almost completely abolished. The observed growth defects could be complemented by the expression of either the L. lactis or the Bacillus subtilis ccpA gene. The disruption of the ccpA gene reduced the catabolite repression of the gal operon, which contains a cre site at the transcription start site and encodes enzymes involved in galactose catabolism. In contrast, CcpA activates the transcription of the cre-containing promoter of the las operon, encoding the glycolytic enzymes phosphofructokinase, pyruvate kinase and L-lactate dehydrogenase, because its transcription level was fourfold reduced in the ccpA mutant strain compared with the wild-type strain. The lower activities of pyruvate kinase and L-lactate dehydrogenase in the ccpA mutant strain resulted in the production of metabolites characteristic of a mixed-acid fermentation, whereas the fermentation pattern of the wild-type strain was essentially homolactic.

Electronic Resource

1365-2958

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Medicine

Cell-density-dependent gene expression appears to be widely spread in bacteria. This quorum-sensing phenomenon has been well established in Gram-negative bacteria, where N-acyl homoserine lactones are the diffusible communication molecules that modulate cell-density-dependent phenotypes. Similarly, a variety of processes are known to be regulated in a cell-density- or growth-phase-dependent manner in Gram-positive bacteria. Examples of such quorum-sensing modes in Gram-positive bacteria are the development of genetic competence in Bacillus subtilis and Streptococcus pneumoniae, the virulence response in Staphylococcus aureus, and the production of antimicrobial peptides by several species of Gram-positive bacteria including lactic acid bacteria. Cell-density-dependent regulatory modes in these systems appear to follow a common theme, in which the signal molecule is a post-translationally processed peptide that is secreted by a dedicated ATP-binding-cassette exporter. This secreted peptide pheromone functions as the input signal for a specific sensor component of a two-component signal-transduction system. Moreover, genetic linkage of the common elements involved results in autoregulation of peptide-pheromone production.

Electronic Resource

1365-2958

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Medicine

The chromosome of Bordetella pertussis harbours a region of 27 contiguous kb, which contains the bvg, fha and flm genes, involved in the co-ordinate regulation of virulence genes, FHA production and fimbriae production, respectively. The linkage of FHA and fimbrial genes has resulted in some confusion concerning the existence and location of genes required for the production of FHA and the function of the fimbrial genes fimB-D, which were proposed to be involved in both FHA and fimbriae biosynthesis. Through the use of non-polar mutations in each of these genes, we found that fimB-D are required for the production of both serotype 2 and 3 fimbriae, but not for FHA biosynthesis. Furthermore, a large open reading frame, designated fhaC, was identified downstream of fimD. It was shown that fhaC is essential for FHA production but not for fimbriae biogenesis. We propose that insertion mutations in fimB-D affect FHA production because of polar effects on fhaC expression. An insertion in the region downstream of fhaC had only a slight effect on FHA and fimbriae production. The fhaC gene product shows homology with ShIB and HpmB, two outer membrane proteins involved in export and activation of the haemolysins, ShIA and HpmA, of Serratia marcescens and Proteus mirabilis, respectively. Homology is also observed between the N-termini of FHA, ShIA and HpmA. Export of the haemolysins requires the Af-termini of these molecules, and when this region was removed from FHA by an in-frame deletion, FHA biosynthesis was abolished. These results suggest that the N-terminus of FHA interacts with FhaC, and that as a result FHA is transported across the outer membrane.

Electronic Resource

1365-2958

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Medicine

Lactococcus lactis strain NIZO B40 produces an extracellular phosphopolysaccharide containing galactose, glucose, and rhamnose. A 40 kb plasmid encoding exopolysaccharide production was isolated through conjugal transfer of total plasmid DNA from strain NIZO B40 to the plasmid-free L. lactis model strain MG1614 and subsequent plasmid curing. A 12 kb region containing 14 genes with the order epsRXABCDEFGHIJKL was identified downstream of an iso-IS982 element. The predicted gene products of epsABCDEFGHIJK show sequence homologies with gene products involved in exopolysaccharide, capsular polysaccharide, lipopolysaccharide, or teichoic acid biosynthesis of other bacteria. Transcriptional analysis of the eps gene cluster revealed that the gene cluster is transcribed as a single 12 kb mRNA. The transcription start site of the promoter was mapped upstream of the first gene epsR. The involvement of epsD in exopolysaccharide (EPS) biosynthesis was demonstrated through a single gene disruption rendering an exopolysaccharide-deficient phenotype. Heterologous expression of epsD in Escherichia coli showed that its gene product is a glucosyltransferase linking the first sugar of the repeating unit to the lipid carrier.

Electronic Resource

1365-2958

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Medicine

Genome analysis has revealed that members of the Lrp family of transcriptional regulators are widely distributed among prokaryotes, both bacteria and archaea. The archetype Leucine-responsive Regulatory Protein from Escherichia coli is a global regulator involved in modulating a variety of metabolic functions, including the catabolism and anabolism of amino acids as well as pili synthesis. Most Lrp homologues, however, appear to act as specific regulators of amino acid metabolism-related genes. Like most prokaryotic transcriptional regulators, Lrp-like regulators consist of a DNA-binding domain and a ligand-binding domain. The crystal structure of the Pyrococcus furiosus LrpA revealed an N-terminal domain with a common helix–turn–helix fold, and a C-terminal domain with a typical αβ-sandwich fold. The latter regulatory domain constitutes a novel ligand-binding site and has been designated RAM. Database analysis reveals that the RAM domain is present in many prokaryotic genomes, potentially encoding (1) Lrp-homologues, when fused to a DNA-binding domain (2) enzymes, when fused as a potential regulatory domain to a catalytic domain, and (3) stand-alone RAM modules with unknown function. The architecture of Lrp regulators with two distinct domains that harbour the regulatory (effector-binding) site and the active (DNA-binding) site, and their separation by a flexible hinge region, suggests a general allosteric switch of Lrp-like regulators.

Electronic Resource

1546-1696

Nature Archives 1869 - 2009

Biology

Process Engineering, Biotechnology, Nutrition Technology

[Auszug] We report the engineering of Lactococcus lactis to produce the amino acid l-alanine. The primary end product of sugar metabolism in wild-type L. lactis is lactate (homolactic fermentation). The terminal enzymatic reaction (pyruvate + NADH→l-lactate + NAD+) is performed by l-lactate ...

Electronic Resource

1546-1696

Nature Archives 1869 - 2009

Biology

Process Engineering, Biotechnology, Nutrition Technology

[Auszug] The extremely thermostable wild type and recombinant β-glucosidases, from Pyrococcus furiosus, served as catalysts for the biotransformation of new glucoconjugates at elevated temperatures. In conversion experiments using the transglucosylation approach, the free or immobilized enzyme accepted ...

Electronic Resource

1546-1696

Nature Archives 1869 - 2009

Biology

Process Engineering, Biotechnology, Nutrition Technology

[Auszug] An attractive approach to accelerate cheese ripening is to induce lysis of Lactococcus lactis starter strains for facilitated release of intracellular enzymes involved in flavor formation. Controlled expression of the lytic genes lytA and lytH, which encode the lysin and the holin proteins of the ...

Electronic Resource

1574-6976

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Electronic Resource

1574-6976

Blackwell Publishing Journal Backfiles 1879-2005

Biology

While lactic acid bacteria and bifidobacteria have been scientifically important for over a century, many of these are marketed today as probiotics and have become a valuable and rapidly expanding sector of the food market that is leading functional foods in many countries. The human gastro-intestinal tract with its various compartments and complex microbiota is the primary target of most of these functional foods containing lactic acid bacteria and bifidobacteria (LAB&B). In addition, their use as vectors for delivery of molecules with therapeutic value to the host via the intestinal tract is being studied. This review focuses on molecular approaches for the investigation of the diversity of lactic acid bacteria and bifidobacteria in the human intestine, as well as tracking of probiotic bacteria within this complex ecosystem. Moreover, methodologies to determine the viability of the lactic acid bacteria and bifidobacteria and molecular approaches to study the mechanisms by which they adapt, establish and interact with the human host via the digestive tract, are described.

Electronic Resource