PubMed Health⌕ Search

Biomedical subjects

M Willer

Publications and source records attributed to M Willer.

12 recordsLinked to original sources
PubMed2004

Randomized clinical trial of lightweight composite mesh for Lichtenstein inguinal hernia repair.

BACKGROUND: Almost half the patients who undergo hernia repair with mesh report a feeling of stiffness and a foreign body in the groin. This study evaluated whether patients noticed any difference between lightweight and standard polypropylene mesh for the repair of inguinal hernia. METHODS: Patients scheduled for elective repair of unilateral or bilateral, primary or recurrent inguinal hernia by the Lichtenstein technique were randomized to receive either a conventional densely woven polypropylene mesh (100-110 g/m(2)) or a lightweight composite multifilament mesh (polypropylene 27-30 g/m(2)). Quality of life was assessed using Short Form 36 before operation and 6 months after surgery. Pain was assessed by means of a visual analogue scale 2 days and 6 months after surgery. The primary outcome measure was the feeling of a foreign body in the groin at 6 months. RESULTS: Some 122 hernias were randomized; 117 were included in the analysis of perioperative data, and 106 were re-examined after 6 months. There were no differences between the treatment groups with respect to early and late surgical complications. Use of lightweight mesh was associated with significantly less pain on exercise after 6 months (P = 0.042). In addition, fewer patients reported the feeling of a foreign body after repair with lightweight mesh (17.2 versus 43.8 per cent with conventional mesh; P = 0.003). Quality of life was improved significantly at 6 months compared with the preoperative assessment, and there were no differences between the treatment groups. CONCLUSION: Lightweight polypropylene mesh may be preferable for Lichtenstein repair of inguinal hernia. Larger cohorts with longer follow-up are needed before it can be recommended for routine use.

Adult↗
PubMed2001

Sec63p and Kar2p are required for the translocation of SRP-dependent precursors into the yeast endoplasmic reticulum in vivo.

The translocation of secretory polypeptides into the endoplasmic reticulum (ER) occurs at the translocon, a pore-forming structure that orchestrates the transport and maturation of polypeptides at the ER membrane. In yeast, targeting of secretory precursors to the translocon can occur by two distinct pathways that are distinguished by their dependence upon the signal recognition particle (SRP). The SRP-dependent pathway requires SRP and its membrane-bound receptor, whereas the SRP-independent pathway requires a separate receptor complex consisting of Sec62p, Sec63p, Sec71p, Sec72p plus lumenal Kar2p/BiP. Here we demonstrate that Sec63p and Kar2p are also required for the SRP-dependent targeting pathway in vivo. Furthermore, we demonstrate multiple roles for Sec63p, at least one of which is exclusive to the SRP-independent pathway.

Cell Membrane↗
PubMed2001

Training affects muscle phospholipid fatty acid composition in humans.

Training improves insulin sensitivity, which in turn may affect performance by modulation of fuel availability. Insulin action, in turn, has been linked to specific patterns of muscle structural lipids in skeletal muscle. This study investigated whether regular exercise training exerts an effect on the muscle membrane phospholipid fatty acid composition in humans. Seven male subjects performed endurance training of the knee extensors of one leg for 4 wk. The other leg served as a control. Before, after 4 days, and after 4 wk, muscle biopsies were obtained from the vastus lateralis. After 4 wk, the phospholipid fatty acid contents of oleic acid 18:1(n-9) and docosahexaenoic acid 22:6(n-3) were significantly higher in the trained (10.9 +/- 0.5% and 3.2 +/- 0.4% of total fatty acids, respectively) than the untrained leg (8.8 +/- 0.5% and 2.6 +/- 0.4%, P < 0.05). The ratio between n-6 and n-3 fatty acids was significantly lower in the trained (11.1 +/- 0.9) than the untrained leg (13.1 +/- 1.2, P < 0.05). In contrast, training did not affect muscle triacylglycerol fatty acid composition. Citrate synthase activity was increased by 17% in the trained compared with the untrained leg (P < 0.05). In this model, diet plays a minimal role, as the influence of dietary intake is similar on both legs. Regular exercise training per se influences the phospholipid fatty acid composition of muscle membranes but has no effect on the composition of fatty acids stored in triacylglycerols within the muscle.

Adult↗
PubMed2001

The S. pombe aurora-related kinase Ark1 associates with mitotic structures in a stage dependent manner and is required for chromosome segregation.

Metazoans contain three aurora-related kinases. Aurora A is required for spindle formation while aurora B is required for chromosome condensation and cytokinesis. Less is known about the function of aurora C. S. pombe contains a single aurora-related kinase, Ark1. Although Ark1 protein levels remained constant as cells progressed through the mitotic cell cycle, its distribution altered during mitosis and meiosis. Throughout G2 Ark1 was concentrated in one to three nuclear foci that were not associated with the spindle pole body/centromere complex. Following commitment to mitosis Ark1 associated with chromatin and was particularly concentrated at several sites including kinetochores/centromeres. Kinetochore/centromere association diminished during anaphase A, after which it was distributed along the spindle. The protein became restricted to a small central zone that transiently enlarged as the spindle extended. As in many other systems mitotic fission yeast cells exhibit a much greater degree of phosphorylation of serine 10 of histone H3 than interphase cells. A number of studies have linked this modification with chromosome condensation. Ark1 immuno-precipitates phosphorylated serine 10 of histone H3 in vitro. This activity was highest in mitotic extracts. The absence of the histone H3 phospho-serine 10 epitope from mitotic cells in which the ark1(+) gene had been deleted (ark1.Delta1); the inability of these cells to resolve their chromosomes during anaphase and the co-localisation of this phospho-epitope with Ark1 early in mitosis, all suggest that Ark1 phosphorylates serine 10 of histone H3 in vivo. ark1.Delta1 cells also exhibited a reduction in kinetochore activity and a minor defect in spindle formation. Thus the enzyme activity, localisation and phenotype arising from our manipulations of this single fission yeast aurora kinase family member suggest that this single kinase is executing functions that are separately implemented by distinct aurora A and aurora B kinases in higher systems.

Anaphase↗
PubMed1999

The yeast CDC9 gene encodes both a nuclear and a mitochondrial form of DNA ligase I.

BACKGROUND: The yeast CDC9 gene encodes a DNA ligase I activity required during nuclear DNA replication to ligate the Okazaki fragments formed when the lagging DNA strand is synthesised. The only other DNA ligase predicted from the yeast genome sequence, DNL4/LIG4, is specifically involved in a non-homologous DNA end-joining reaction. What then is the source of the DNA ligase activity required for replication of the yeast mitochondrial genome? RESULTS: We report that CDC9 encodes two distinct polypeptides expressed from consecutive in-frame AUG codons. Translational initiation at these two sites gives rise to polypeptides differing by a 23 residue amino-terminal extension, which corresponds to a functional mitochondrial pre-sequence sufficient to direct import into yeast mitochondria. Initiation at the first AUG codon results in a 755 amino-acid polypeptide that is imported into mitochondria, whereupon the pre-sequence is proteolytically removed to yield the mature mitochondrial form of Cdc9p. Initiation at the second AUG codon produces a 732 amino-acid polypeptide, which is localised to the nucleus. Cells expressing only the nuclear isoform were found to be specifically defective in the maintenance of the mitochondrial genome. CONCLUSIONS: CDC9 encodes two distinct forms of DNA ligase I. The first is targeted to the mitochondrion and is required for propagation and maintenance of mitochondrial DNA, the second localises to the nucleus and is sufficient for the essential cell-division function associated with this gene.

Amino Acid Sequence↗
PubMed1998

Nutation-Frequency Correlated EPR Spectroscopy: The PEANUT Experiment

The phase-inverted echo-amplitude detected nutation (PEANUT) experiment for the measurement of transient electron spin nutation frequencies is introduced. In this new pulse sequence, nutation refocused to a rotary echo is detected via the amplitude modulation of a primary electron spin echo. Since detection and excitation of the nutation are fully separated in time, experiments at very high nutation frequencies become feasible. The nutation frequencies which are proportional to the transition moment of an EPR transition can be used to label individual EPR lines by an additional parameter. Using a two-dimensional PEANUT experiment which correlates the nutation frequencies with the resonance fields, the interpretation of complicated field-swept EPR spectra can considerably be simplified. A theoretical description of the experiment is given and the inner working of the approach is described. The predicted features of PEANUT spectra are verified experimentally and examples of applications to both ordered and disordered systems are given. Copyright 1998 Academic Press. Copyright 1998 Academic Press

Journal Article↗
PubMed1998

Two-dimensional nuclear-Zeeman-resolved electron spin echo envelope modulation (NZ-ESEEM) spectroscopy.

A two-dimensional electron spin echo envelope modulation (ESEEM) experiment, called nuclear-Zeeman-resolved ESEEM (NZ-ESEEM), that correlates nuclear transition frequencies with nuclear Zeeman frequencies is introduced. NZ-ESEEM is basically a three-pulse ESEEM experiment complemented by a magnetic-field pulse applied during part of the free evolution period between the second and third microwave pulse. The inner working of the new approach is explained and the instrumentation is discussed. The capacity of the method is illustrated by two examples of applications.

Algorithms↗
PubMed1995

Two-step activation of meiosis by the mat1 locus in Schizosaccharomyces pombe.

The mat1 locus is a key regulator of both conjugation and meiosis in the fission yeast Schizosaccharomyces pombe. Two alternative DNA segments of this locus, mat1-P and mat1-M, specify the haploid cell types (Plus and Minus). Each segment includes two genes: mat1-P includes mat1-Pc and mat1-Pm, while mat1-M includes mat1-Mc and mat1-Mm. The mat1-Pc and mat1-Mc genes are responsible for establishing the pheromone communication system that mediates conjugation between P and M cells, while all four mat1 genes are required for meiosis in diploid P/M cells. Our understanding of the initiation of meiosis is based largely on indirect observations, and a more precise investigation of these events was required to define the interaction between the mat1 genes. Here we resolve this issue using synthetic pheromones and P/M strains with mutations in either mat1-Pc or mat1-Mc. Our results suggest a model in which the mat1 locus plays two roles in controlling meiosis. In the first instance, the mat1-Pc and mat1-Mc functions are required to produce the mating pheromones and receptors that allow the generation of a pheromone signal. This signal is required to induce the expression of mat1-Pm and mat1-Mm. This appears to be the major pheromone-dependent step in controlling meiosis since ectopic expression of these genes allows meiosis in the absence of mat1-Pc and mat1-Mc. The mat1-Pm and mat1-Mm products complete the initiation of meiosis by activating transcription of the mei3 gene.

Base Sequence↗
PubMed1994

Assessment of pheromone production and response in fission yeast by a halo test of induced sporulation.

We describe a rapid, sensitive and semi-quantitative plate assay for monitoring pheromone activity in the fission yeast Schizosaccharomyces pombe. It is based on the observation that meiosis requires stimulation by pheromone and exploits diploid strains that will only sporulate after addition of exogenous pheromone. The tester strains are heterozygous for mating type, are non-switching, and are mutated in one of the early subfunctions (either mat1-Mc or mat1-Pc), so that meiosis is only induced after exposure to exogenous pheromone (M-factor or P-factor, respectively). Pheromone activity is assessed as an iodine-positive halo of sporulation surrounding the pheromone source, and the width of the halo is related to the amount of pheromone being produced. The assay is sufficiently sensitive to monitor the low amount of M-factor produced by an M mam1 strain, and its sensitivity towards P-factor is greatly increased by using a hyper-sensitive tester strain lacking the Sxa2 protease that is believed to degrade this pheromone. We also demonstrate that the production of P-factor is very much stimulated by exposure of P cells to M-factor.

Pheromones↗
PubMed1980

[Experimental study on the "traumatogenic" eosinophilic granuloma of the tongue].

According to Bhaskar and Lilly, experimental results with rat tongues indicated that trauma is the cause of the rare eosinophilic granuloma of the human tongue. On the basis of similar experimental investigations, we consider this conclusion to be incorrect. In our opinion, the etiology of eosinophilic granuloma of the tongue as that of other eosinophilic granulomas in man is still unknown.

Animals↗