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Biomedical subjects

S Will

Publications and source records attributed to S Will.

At least 19 recordsLinked to original sources
PubMed2006

Stenting of the superficial femoral artery after suboptimal balloon angioplasty: one-year results.

AIM: The aim of this study was to analyze the intermediate results of selective stenting of superficial femoral artery (SFA) lesions after a suboptimal balloon angioplasty result. METHODS: We analyzed 70 consecutive patients with claudication or critical limb ischemia due to peripheral arterial occlusive disease who underwent stent implantation of the SFA after unsuccessful balloon-angioplasty. All patients were followed-up immediately after the procedure and 3, 6 and 12 months thereafter. Restenosis was defined as an increase of peak systolic velocity-index >2 as determined by duplex sonography. RESULTS: Primary patency rates at 3, 6 and 12 months were 83.4%, 66.2% and 59%, respectively. Successful reinterventions were performed for 17 reobstructions, resulting in a secondary patency rate at 3, 6 and 12 months of 91%, 89.3%, and 83.8%, respectively. At 12 months 68.6% of the patients were asymptomatic, 21.6% complained of mild (Fontaine class II a), 5.9% of severe (Fontaine class II b) claudication and 2.9% were in critical limb ischemia. CONCLUSIONS: Our data indicate that selective stenting of the SFA after suboptimal balloon angioplasty results in intermediate patency rates similar to that reported for primarily successful PTA, thereby supporting the widely accepted policy of selective stenting as a rescue procedure after unsuccessful balloon angioplasty.

Aged↗
PubMed2002

Metastatic pathways and time courses in the orderly progression of cutaneous melanoma.

BACKGROUND: It is known that two-thirds of patients who develop clinical metastases following treatment of a primary cutaneous melanoma initially present with locoregional metastases and one-third initially present with distant metastases. However, few reports in the literature give detailed figures on different metastatic pathways in cutaneous melanoma. OBJECTIVES: The aim of the present study was to perform a detailed analysis of the different metastatic pathways, the time course of the development of metastases and the factors influencing them. METHODS: In a series of 3001 patients with primary cutaneous melanoma at first presentation, 466 subsequently developed metastasis and were followed-up over the long term at the University of Tuebingen, Germany between 1976 and 1996. Different pathways of metastatic spread were traced. Associated risk factors for the different pathways were assessed. Differences in survival probabilities were calculated by the Kaplan-Meier method and evaluated by the log-rank test. RESULTS: In 50.2% of the patients the first metastasis after treatment of the primary tumour developed in the regional lymph nodes. In the remaining half of the patient sample the first metastasis developed in the lymphatic drainage area in front of the regional lymph nodes, as satellite or in-transit metastases (21.7%) or as direct distant metastases (28.1%). Anatomical location, sex and tumour thickness were significant risk factors for the development of metastasis by different pathways. The most important risk factor appeared to be the location of the primary tumour. The median intervals elapsing before the first metastasis differed significantly between the different metastatic pathways. The direct distant metastases became manifest after a median period of 25 months, thus later than the direct regional lymph node metastases (median latency period, 16 months) and the direct satellite and in-transit metastases (median latency period, 17 months). In patients who developed distant metastases the period of development was independent of the metastatic route. The time at which the distant metastases developed was roughly the same (between 24 and 30 months after the detection of the primary tumour), irrespective of whether satellite or in-transit metastases, lymph node metastases or distant metastases were the first to occur. CONCLUSIONS: The time course of the development of distant metastasis was more or less the same irrespective of the metastatic pathway; this suggests that in patients with in-transit or satellite metastasis or regional lymph node metastasis, haematogenic metastatic spread had already taken place. Thus, the diagnostic value of sentinel lymph node biopsy and the therapeutic benefit of elective lymph node dissection may be limited, as satellite and in-transit metastases or direct distant metastases will not be detected and haematogenous spread may already have taken place when the intervention is performed.

Adolescent↗
PubMed2001

Mercury contamination incident.

BACKGROUND: The aim of this paper is to describe an incident where elemental mercury led to widespread contamination and the exposure of 225 individuals and confirmed toxicity in 19 individuals. The paper describes the incident and difficulties found in trying to assess the risk to individuals and to identify and decontaminate the residences involved. METHODS: All individuals exposed to elemental mercury in the incident were followed up for 15 months. RESULTS: Thirty-seven individuals were found to be 'at risk' and 13 were symptomatic of mercury poisoning. Five patients required chelation therapy. The incident was closed when the risk of poisoning and re-exposure was minimized. CONCLUSION: Incident management depends on early effective communication and collaboration between all agencies involved.

Adolescent↗
PubMed2000

Corroles with group 15 ions. 2. Synthesis and characterization of octaethylcorroles containing a phosphorus central atom.

The synthesis, spectroscopic characterization, and electrochemistry of five new phosphorus corroles are reported. The investigated complexes contain alkyl, aryl, oxo, or hydrido axial ligands and are represented as (OEC)P(H)2, (OEC)P(CH3)2, (OEC)P(C6H5)2, (OEC)P=O, and [(OEC)P(CH3)]+ClO4-, where OEC is the trianion of octaethylcorrole. The products of electrooxidation and/or electroreduction were also characterized by UV-vis and ESR spectroscopy. Correlations are shown to exist between reversible half-wave potentials for the first oxidation and first reduction of each compound and the combined electronegativity of the central ion and the axial ligand(s). The electrochemical HOMO-LUMO gap, defined as the difference between first reduction and first oxidation, was found to be independent of the electron-transfer site and similar in magnitude to the value generally observed for metalloporphyrins with planar macrocycles, i.e., 2.25 +/- 0.15 V.

Journal Article↗
PubMed2000

Corroles with group 15 metal ions. Synthesis and characterization of octaethylcorroles containing As, Sb, and Bi ions in +3, +4, and oxidation states.

The synthesis, spectroscopic characterization, and electrochemistry of As, Sb, and Bi corroles are reported. The investigated complexes are represented by [(OEC)AsV(CH3)]+ClO4- and (OEC)M where M = As(III), Sb(III), or Bi(III) and OEC is the trianion of octaethylcorrole. The products of each redox reaction are characterized by UV-vis and ESR spectroscopy. The first one-electron oxidations of (OEC)As and (OEC)Sb are metal-centered and result in the formation of [(OEC)AsIV]+ and [(OEC)SbIV]+. A second one-electron oxidations generates [(OEC)AsV]2+ and [(OEC.)SbIV]2+, the latter of which is slowly converted to a Sb(V) corrole, [(OEC)SbV]2+. The first one-electron oxidation of (OEC)Bi leads only to the Bi(III) pi-cation radical, but a second one-electron oxidation is proposed to give a Bi(IV) complex, [(OEC)Bi]2+. The first reduction of [(OEC)AsV(CH3)]+ClO4- is accompanied by loss of the sigma-bonded methyl ligand and formation of an As(III) complex.

Journal Article↗
PubMed2000

Algorithmic approach to quantifying the hydrophobic force contribution in protein folding.

Though the electrostatic, ionic, van der Waals, Lennard-Jones, hydrogen bonding, and other forces play an important role in the energy function minimized at a protein's native state, it is widely believed that the hydrophobic force is the dominant term in protein folding. Here we attempt to quantify the extent to which the hydrophobic force determines the positions of the backbone alpha-carbon atoms in PDB data, by applying Monte-Carlo and genetic algorithms to determine the predicted conformation with minimum energy, where only the hydrophobic force is considered (i.e. Dill's HP-model, and refinements using Woese's polar requirement). This is done by computing the root mean square deviation between the normalized distance matrix D = (di,j) (di,j is normalized Euclidean distance between residues ri and rj) for PDB data with that obtained from the output of our algorithms. Our program was run on the database of ancient conserved regions drawn from GenBank 101 generously supplied by W. Gilbert's lab, as well as medium-sized proteins (E. Coli RecA, 2reb, Erythrocruorin, 1eca, and Actinidin 2act). The root mean square deviation (RMSD) between distance matrices derived from the PDB data and from our program output is quite small, and by comparison with RMSD between PDB data and random coils, allows a quantification of the hydrophobic force contribution. A preliminary version of this paper appeared at GCB'99 (http:¿bibiserv.techfak.uni-bielefeld.de/gcb9 9/).

Algorithms↗
PubMed1999

PCDDs, PCDFs, PCBs and HCB in marine and estuarine sediments from Queensland, Australia.

Concentrations of 2,3,7,8-chlorine substituted PCDDs, PCDFs, selected PCB congeners and HCB were determined in sediment samples collected from sites along the east coast of Queensland in northern Australia. PCDDs were detectable in all sediment samples while PCDFs, PCBs and HCB were mainly found in sediment samples collected from sites in the Brisbane metropolitan area. The results provide evidence that an unidentified source for higher chlorinated PCDDs exists along the Queensland coast.

Australia↗
PubMed1999

Application of constraint programming techniques for structure prediction of lattice proteins with extended alphabets.

MOTIVATION: Predicting the ground state of biopolymers is a notoriously hard problem in biocomputing. Model systems, such as lattice proteins, are simple tools and valuable to test and improve new methods. Best known are models with sequences composed from a binary (hydrophobic and polar) alphabet. The major drawback is the degeneracy, i.e. the number of different ground state conformations. RESULTS: We show how recently developed constraint programming techniques can be used to solve the structure prediction problem efficiently for a higher order alphabet. To our knowledge it is the first report of an exact and computationally feasible solution to model proteins of length up to 36 and without resorting to maximally compact states. We further show that degeneracy is reduced by more than one order of magnitude and that ground state conformations are not necessarily compact. Therefore, more realistic protein simulations become feasible with our model.

Algorithms↗
PubMed1995

Physicochemical studies of the d(G3T4G3)*d(G3A4G3).d(C3T4C3) triple helix.

We have targeted the d(G3A4G3).d(C3T4C3) duplex for triplex formation with d(G3T4G3) in the presence of MgCl2. The resulting triple helix, d(G3T4G3)*d(G3-A4G3).d(C3T4C3), is considerably weaker than the related triplex, d(G3A4G3)*d(G3A4G3).d(C3T4C3), and melts in a biphasic manner, with the third strand dissociating at temperatures about 20-30 degrees C below that of the remaining duplex. This is in distinct contrast to the d(G3A4G3)*d(G3A4G3).d(C3T4C3) triplex, which melts in essentially a single transition. Gel electrophoresis under non-denaturing conditions shows the presence of the d(G3T4G3)*d(G3A4G3).d(C3T4C3) triplex as a band of low mobility compared to the duplex or the single strand bands. Binding of the d(G3T4G3) third strand and the purine strand of the duplex can be monitored by imino proton NMR spectra. While these spectra are typically very broad for intermolecular triplexes, the line widths can be dramatically narrowed by the addition of two thymines to both ends of the pyrimidine strand. Thermodynamic analysis of UV melting curves shows that this triplex is considerably less stable than related triplexes formed with the same duplex. The orientation of the third strand was addressed by a combination of fluorescence energy transfer and UV melting experiments. Results from these experiments suggest that, in the unlabeled triplex, the preferred orientation of the third strand is parallel to the purine strand of the duplex.

Base Sequence↗
PubMed1994

[Introduction of an infection registration program for surgical wound infection based on the WHOCARE software of WHO].

Surveillance of surgical wound-infection (SWI) is an important instrument in the internal and external quality control in surgery. In the past it has been shown that statistics on surgical wound infection are helpful for reduction of wound infection rates. With the engagement of nurses for clinical hygiene at our hospital we had the possibility to evaluate programs for surveillance of nosocomial infection. In a pilot study we began with the surveillance of SWI. The set of data registered was defined by WHOCARE, the software-package used in the study which is distributed by the WHO Europe. Criteria of the NNIS-Study for SWI were applied. Between March and December 1992 approximately 1.300 surgical interventions had been registered. Although the dataset in WHOCARE is limited with regard to an easy surveillance, it was possible to find out infection rates dependent on all major parameters. Additionally reports on individual infection rates and tables containing information of infected cases were sent to every surgeon. By analyzing some of the problems detected during the study, we developed an improved protocol for routine surveillance of SWI. In the future it will save time and will allow the best quality of collected data in narrow collaboration between the departments of microbiology, clinical hygiene and surgery. This protocol should be transferable to other hospitals and represents an anticipated precautious measure with regard to legal regulations on quality control in medicine.

Cross Infection↗
PubMed1991

Strength training does not improve lipoprotein-lipid profiles in men at risk for CHD.

Sixteen untrained males, age 46 +/- 11 yr (mean +/- SD), were studied to determine the effects of 20 wk of strength training on lipoprotein-lipid profiles and post-heparin lipase activities. All subjects had abnormal lipoprotein-lipid profiles and at least two other risk factors for coronary heart disease (CHD). To control for day-to-day variations in blood lipoprotein levels, baseline values were established by taking at least two blood samples on separate days from the training and control groups. The training program resulted in a 50% increase in upper body strength (P less than 0.001) and a 37% increase in lower body strength (P less than 0.001) as measured by the one repetition maximum test (1-RM). No changes in the 1-RM test were observed in the control group. There were no significant changes in VO2max (34.5 +/- 6.4 vs 36.2 +/- 7.4 ml.kg-1.min-1 or percent fat (25.4 +/- 4.2 vs 24.9 +/- 4.1%) with training. There were also no significant changes in plasma concentrations of triglyceride (193 +/- 96 vs 171 +/- 101 mg.dl-1), total cholesterol (231 +/- 22 vs 210 +/- 22 mg.dl-1), and HDL-C (35 +/- 6 vs 36 +/- 8 mg.dl-1), or LDL-C (139 +/- 16 vs 139 +/- 21 mg.dl-1). Furthermore, the activities of post-heparin lipoprotein lipase (9 +/- 4 vs 13 +/- 5 moles.ml-1.h-1) and hepatic lipase (35 +/- 10 vs 35 +/- 9 moles.ml-1.h-1) did not change with training.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Effects of strength training on lactate threshold and endurance performance.

To determine the effects of 12 wk of strength training on lactate threshold (LT) and endurance performance, 18 healthy untrained males between 25 and 34 yr of age were randomly assigned to either strength training (N = 10) or control (N = 8) groups. Despite no changes in treadmill VO2max or cycle peak VO2, a 33 +/- 5% increase (P less than 0.001) in cycling time to exhaustion at 75% of peak VO2 was observed following training. No significant changes in cycling time were observed in the control group. There were significant reductions in plasma lactate concentration at all relative exercise intensities ranging between 55 and 75% of peak VO2 training. The improved endurance performance was associated with a 12% increase in LT (r = 0.78, P less than 0.001). The strength training program resulted in significant improvements (P less than 0.001) of 31 +/- 5% and 35 +/- 7% in isokinetic peak torque values for leg extension and flexion, respectively, at a velocity of 30 degrees.s-1. There were also significant increases in 1-RM values of 30 +/- 4% (P less than 0.001) for leg extension, 52 +/- 6% (P less than 0.001) for leg flexion, and 20 +/- 4% (P less than 0.001) for the bench press. These findings indicate that strength training improves cycle endurance performance independently of changes in VO2max. This improved performance appears to be related to increases in LT and leg strength.

Adult↗
PubMed1990

[Sonographic findings of the mammary papilla of cattle].

Morphological structures of the bovine Papilla mammae can be differentiated with portable ultrasound units and 5 MHz linear arrays. For practical use it is possible to scan the teat in a water-filled plastic cup as a kind of water delay system. The visualization of pathological findings shows a possibility to evaluate this method as a diagnostic tool for the bovine teat.

Animals↗
PubMed1989

Evidence for the dominance of direct excitation of DNA in the formation of strand breaks in cells following irradiation.

The yields of radiation-induced strand breaks measured in a plasmid DNA irradiated as a 'dry film' are similar to those measured in SV40 DNA irradiated in a cellular environment (Roots et al. 1985). This suggests a common mechanism, namely direct excitation of the DNA rather than indirectly inflicted damage from radiation-induced water radicals. This result is discussed in terms of a recently proposed mechanism of excitation transfer in DNA following direct excitation by ionizing radiation.

DNA↗
PubMed1988

Targeted mutations induced by a single acetylaminofluorene DNA adduct in mammalian cells and bacteria.

Mutagenic specificity of 2-acetylaminofluorene (AAF) has been established in mammalian cells and several strains of bacteria by using a shuttle plasmid vector containing a single N-(deoxyguanosin-8-yl)acetylaminofluorene (C8-dG-AAF) adduct. The nucleotide sequence of the gene conferring tetracycline resistance was modified by conservative codon replacement so as to accommodate the sequence d(CCTTCGCTAC) flanked by two restriction sites, Bsm I and Xho I. The corresponding synthetic oligodeoxynucleotide underwent reaction with 2-(N-acetoxy-N-acetylamino)-fluorene (AAAF), forming a single dG-AAF adduct. This modified oligodeoxynucleotide was hybridized to its complementary strand and ligated between the Bsm I and Xho I sites of the vector. Plasmids containing the C8-dG-AAF adduct were used to transfect simian virus 40-transformed simian kidney (COS-1) cells and to transform several AB strains of Escherichia coli. Colonies containing mutant plasmids were detected by hybridization to 32P-labeled oligodeoxynucleotides. Presence of the single DNA adduct increased the mutation frequency by 8-fold in both COS cells and E. coli. Over 80% of mutations detected in both systems were targeted and represented G.C----C.G or G.C----T.A transversions or single nucleotide deletions. We conclude that modification of a deoxyguanosine residue with AAF preferentially induces mutations targeted at this site when a plasmid containing a single C8-dG-AAF adduct is introduced into mammalian cells or bacteria.

2-Acetylaminofluorene↗