Biomedical subjects

H Meyer

Publications and source records attributed to H Meyer.

At least 19 recordsLinked to original sources

PubMed2006

Perturbation-controlled numerical simulations of the convection onset in a supercritical fluid layer.

This paper reports 2D and 3D direct numerical simulations of the Rayleigh-Bénard convection in a fluid layer, 3He, close to its gas-liquid critical point. The main quantity of interest is the time when the convective motion becomes appreciable after the heat current has been started. A space periodic, time-independent temperature perturbation is applied to the top plate aiming to represent the various sources of noise in the experiments. A single amplitude of this additional perturbation reproduces the noise level of the experiments for all the used combinations of the critical point proximity and of the heating power. Over four decades of the Rayleigh number, this simple operation removes the systematic discrepancy reported in an earlier paper and brings the simulations into good agreement with the measurements. Scaling of the exponential convection growth rate is presented and discussed.

Journal Article↗

PubMed2006

Onset of the convection in a supercritical fluid.

A model is proposed that leads to the scaled relation tp/tau D=Ftp(Ra-Rac) for the development of convection in a pure fluid in a Rayleigh-Bénard cell after the start of the heat current at t=0. Here tp is the time of the first maximum of the temperature drop DeltaT(t) across the fluid layer, the signature of rapidly growing convection, tau D is the diffusion relaxation time, and Rac is the critical Rayleigh number. Such a relation was first obtained empirically from experimental data. Because of the unknown perturbations in the cell that lead to convection development beyond the point of the fluid instability, the model determines tp/tau D within a multiplicative factor Psi square root Rac(HBL), the only fit parameter product. Here Rac(HBL), of the order 10(3), is the critical Rayleigh number of the hot boundary layer and Psi is a fit parameter. There is then good agreement over more than four decades of Ra-Rac between the model and the experiments on supercritical 3He at various heat currents and temperatures. The value of the parameter Psi, which phenomenologically represents the effectiveness of the perturbations, is discussed in connection with predictions by El Khouri and Carlès of the fluid instability onset time.

Journal Article↗

PubMed2006

Photophysical properties of Hypericum perforatum L. extracts--novel photosensitizers for PDT.

We report the preparation of the methanolic extract (ME), and polar methanolic fraction (PMF) from the plant Hypericum perforatum L. The extracts contain various photosensitizing constituents such as naphthodianthrone derivatives (in 1.37% w/w), and chlorophylls (in 0.08% w/w). Upon light emission these constituents can be activated, providing photodynamic properties to the extracts, and making them a potent, new class, natural photosensitizers for use in photodynamic therapy (PDT), and photodynamic diagnosis (PDD). The absorbance spectra of the extracts are similar to the spectrum of hypericin, the main naphthodianthrone identified within, with two major bands at 548 and 590 nm. The fluorescence spectra in ethanol exhibit two main bands around 595 and 640 nm, in accordance with the spectrum of pure hypericin. The fluorescence intensity of PMF at 595 nm is only eight times less than the intensity of pure hypericin at the same wavelength, even though its hypericin concentration is only 0.57% w/w. The dependence of the PMF fluorescence signal on the pH of the medium, alone and in comparison with the signal of hypericin, has been investigated. PMF signal fades steadily, and smoothly both in acidic, and basic environment.

Anthracenes↗

PubMed2006

Response of male BUT big 6 turkeys to varying amino acid feeding programs.

Dietary protein is a major cost contributor in turkey nutrition. Therefore, a feeding trial with male BUT Big 6 turkeys to 154 d of age was conducted to examine how live performance and economics are affected when dietary amino acid levels are altered in different phases. Six dietary treatments were run with treatment 1 as the control in which balanced protein levels were according to recommendations during all 6 phases. Treatments 2 through 6 used combinations of balanced protein (based on lysine) that ranged from 90 to 120% of those used in treatment 1. The combinations for the 6 phases of feeding were 120, 120, 120, 120, 90, and 90% for treatment 2; 120, 120, 120, 100, 90, and 90% for treatment 3; 120, 120, 100, 100, 90, and 90% for treatment 4; 120, 120, 120, 120, 100, and 100% for treatment 5; and 90, 90, 90, 100, 100, and 100 for treatment 6. Final BW was highest in treatment 4 and lowest in treatment 2 (P < 0.05), whereas final BW were intermediate and statistically not different in treatments 1, 3, 5, and 6. Breast meat yield was highest in treatment 5 and lowest in treatments 2 and 3 (P < 0.05). Mortality seemed to be reduced in treatment 6 compared with treatments 2, 3, and 5 (P < 0.10). Performance data in combination with economic simulations suggested that the feeding regimens of treatments 4 or 6 might be alternative strategies to treatment 1 to improve overall profitability.

Amino Acids↗

PubMed2006

Detection of Burkholderia cepacia DNA from artificially infected EDTA-blood and lung tissue comparing different DNA isolation methods.

Bacterial DNA (Burkholderia cepacia) was prepared from artificially infected equine ethylenediaminetetraacetic acid (EDTA)-blood and lung tissue by using four standard methods (lysis buffer containing proteinase K, phenol/chloroform/isoamylalcohol-extraction, microwave-treatment, heat treatment) and six commercially available kits (Puregene, High Pure PCR Template Preparation Kit, InstaGene, QiaAmp Tissue Kit, DNAzol and Elu-Quik). After a subsequent polymerase chain reaction (PCR), their efficacy and sensitivity were compared. Concerning the detection limits, the simple lysis with a proteinase K-containing buffer led to the best results for EDTA-blood as well as for artificially infected lung tissue.

Animals↗

PubMed2006

[What did pigs look like in the Middle Ages?].

The conformation of medieval swine is less well documented by written reports or osteological states. This paper evaluates the conformation of medieval pigs from about 140 pictures of various sources (books of hours, misericords, illustration of bibles text or proverbs, sculptures etc.). The pictures demonstrate that medieval pigs mainly were long legged, slender, razor backed, bristly with long snouts and prick ears (Tab. 1) well adapted for herding in forests and waste land. In mediterranean countries in early and high Middle Ages as well as in some regions of France and England in the late Middle Ages compact animals with shorts snouts and lopears were depicted. Probably these typs resulted from other housing and feeding conditions (stall feeding with wastes from fields, gardens, kitchen etc.). Medieval pigs were one-coloured white, grey, black and sometimes red, pictures from saddle-back animals came from Italy or south Germany.

Animal Husbandry↗

PubMed2005

Numerical simulation studies of the convective instability onset in a supercritical fluid.

Numerical simulation studies in 2D with the addition of noise are reported for the convection of a supercritical fluid, 3He , in a Rayleigh-Bénard cell. The noise addition is to accelerate the instability growth after starting the heat flow across the fluid, so as to bring simulations into better agreement with published experimental observations. Homogeneous temperature noise and spatial longitudinal periodic temperature variations in either top or bottom plates were programmed into the simulations. The second method was the most effective in speeding up the instability onset. For a small amplitude of the longitudinal perturbations, a semiquantitative agreement with the observations was obtained. The results are discussed in relation to predictions by El Khouri and Carlès.

Journal Article↗

PubMed2005

The ECRL bone-tendon ligamentoplasty for chronic ulnar instability of the metacarpophalangeal joint of the thumb.

We report the results of a new bone-tendon ligamentoplasty for the reconstruction of chronic injuries of the ulnar collateral ligament at the metacarpophalangeal joint of the thumb. The mean follow-up period was 36 months. Using the Glickel grading system, seven patients had excellent results and one patient had good results. The mean loss of pinch strength was 10% compared with the contralateral thumb. The mean loss of motion at the MP joint was 8%. This technique successfully restores the desired long lasting stability while maintaining mobility of the thumb's metacarpophalangeal joint.

Adult↗

PubMed2005

An easy-to-use semiquantitative food record validated for energy intake by using doubly labelled water technique.

BACKGROUND: Estimating dietary intake is important for both epidemiological and clinical studies, but often lacks accuracy. OBJECTIVE: To investigate the accuracy and validity of energy intake estimated by an easy-to-use semiquantitative food record (EI(SQFR)) compared to total energy expenditure (TEE) estimated by doubly labelled water technique (EE(DLW)). DESIGN: TEE was measured in 29 nonobese subjects using the doubly labelled water method over a period of 14 days. Within this period, subjects reported their food consumption by a newly developed semiquantitative food record for 4 consecutive days. Energy intake was calculated using the German Food Code and Nutrition Data Base BLS II.3. RESULTS: A good correlation was observed between EI(SQFR) and EE(DLW) (r = 0.685, P < 0.001). The mean difference between EI(SQFR) and EE(DLW) was -1.7+/-2.6 MJ/day (-14+/-21%, P = 0.002). An underestimation of EI(SQFR) <10% was observed in nine subjects (31%), of 10-20% in six subjects (21%), and of >20% in nine subjects (31%). In five subjects (17%), an overestimation of EI(SQFR) was observed. CONCLUSIONS: The easy-to-use semiquantitative food record provided good estimates of EI in free-living and nonobese adults without prior detailed verbal instructions. The presented food record has limitations regarding accuracy at the individual level.

Adult↗

PubMed2005

Validation of a simplified physical activity record by doubly labeled water technique.

INTRODUCTION: For obtaining reliable information about physical activity in epidemiological studies, validated and easy-to-use instruments are required. Therefore, a new simplified physical activity record based on 15-min recording intervals was developed and validated. SUBJECTS: Nonobese volunteers (n = 31). MEASUREMENTS: Physical activity was recorded over a 7-day period without detailed instructions. Energy expenditure was calculated (EE(sPAR)) and compared to energy expenditure measured by doubly labelled water technique (EE(DLW)). RESULTS: A good agreement between EE(sPAR) (12.1+/-3.0) and EE(DLW) (11.7+/-3.3) with a mean difference of 0.33+/-1.55 MJ (r = 0.880, P < 0.001) was observed. The absolute difference between EE(sPAR) and EE(DLW) was < 10% in 65% of the subjects. The difference between EE(sPAR) and EE(DLW) was independent of gender, age, body weight, and body mass index. A weak positive association between the difference and total body fat was observed (r = 0.618, P < 0.001), suggesting a slight tendency to overestimate EE(sPAR) with increasing total body fat. CONCLUSION: The new simplified physical activity protocol needs no detailed instructions, provides valid estimates of physical activity in nonobese free-living adults and can be used in epidemiological studies to assess total daily energy expenditure and physical activity level.

Activities of Daily Living↗

PubMed2005

Cohort analysis of asylum seekers in Oslo, Norway, 1987-1995: effectiveness of screening at entry and TB incidence in subsequent years.

SETTING: Municipalities of Baerum and Oslo, Norway. OBJECTIVES: To examine the effectiveness of tuberculosis (TB) screening in asylum seekers 1987-1995, and to describe TB incidence rates after arrival. DESIGN: Register-based, retrospective cohort study of 19912 asylum seekers with a mean follow-up of 6.3 years. RESULTS: Seventy-six persons were diagnosed with TB, of whom 43 (57%) had pulmonary TB. Twenty-two cases (17 pulmonary) were found through screening at entry. Eleven persons had abnormal mass miniature X-rays (MMRs), but had inadequate follow-up and were diagnosed later through passive case finding. MMR itself had a sensitivity of 96% and a specificity of 98% for pulmonary TB, diagnosed within 1 year after arrival. TB prevalence at entry was 110/100000; for Somalis it was 577/100000. Incidence rates were stable in the total cohort after arrival, whereas rates for extra-pulmonary TB in Somalis increased. CONCLUSIONS: Screening on entry should continue, but follow-up of abnormal MMRs must be improved. There should be more emphasis on treatment of latent infection.

Adult↗

PubMed2005

[The morphology of domestic pigs in middle Europe during the 16th to 18th century].

The external of swine in Mideurope during the 16th to 18th century will be described based on a few publications and various pictures (120). Long legged, slender, bristly pigs with long snouts and prick ears dominated during the 16th century, sometimes, however, compact animals with shorter snouts and larger prick or lope ears have been depicted (Tab. 1). During the 17th century no correct descriptions of the pigs are avaiable. The pictures show similar types as in the century before (tab. 1). In pig herds the heterogenity especially of heads and ears in pigs kept in this time is demonstrated. During the 18th century agriculturists postulate long pigs as well as compact types. On the (few) pictures in this century more compact animals with short snouts and long ears have been presented, partly from England probably with the influence of imported asiatic pigs. From the 2 dominating types of land races in Mideurope at the end of the 18th century (small, prick eared or large with lope ears) the former may be derived from the medieval mideuropean pig, while the second one may arise from imports from mediterranean countries and crossings.

Animal Husbandry↗

PubMed2004

Long range bond-bond correlations in dense polymer solutions.

The scaling of the bond-bond correlation function P1(s) along linear polymer chains is investigated with respect to the curvilinear distance s along the flexible chain and the monomer density rho via Monte Carlo and molecular dynamics simulations. Surprisingly, the correlations in dense three-dimensional solutions are found to decay with a power law P1(s) approximately s(-omega) with omega=3/2 and the exponential behavior commonly assumed is clearly ruled out for long chains. In semidilute solutions, the density dependent scaling of P1(s) approximately g(-omega(0))(s/g)(-omega) with omega(0)=2-2nu=0.824 (nu=0.588 being Flory's exponent) is set by the number of monomers g(rho) in an excluded volume blob. Our computational findings compare well with simple scaling arguments and perturbation calculation. The power-law behavior is due to self-interactions of chains caused by the chain connectivity and the incompressibility of the melt.

Journal Article↗

PubMed2004

Molecular beam scattering of NO+Ne: a joint theoretical and experimental study.

The collision dynamics of the NO+Ne system is investigated in a molecular beam scattering experiment at a collision energy of 1055 cm(-1). Employing resonance enhanced multiphoton ionization of NO, we measured state-resolved integral and differential cross sections for the excitation to various levels of both spin-orbit manifolds. The dependence of the scattered intensity on the laser polarization is used to extract differential quadrupole moments for the collision induced angular momentum alignment. The set of cross section data is compared with results of a full quantum mechanical close coupling calculation using the set of ab initio potential energy surfaces of Alexander et al. [J. Chem. Phys. 114, 5588 (2001)]. In previous work, it was found that the positions and rotational substructures for the lowest bend-stretch vibrational states derived from these surfaces agree very well with the observed spectrum of the NO-Ne complex. For the same potential, we find that the calculated cross sections show a less satisfactory agreement with the experimental data. While the overall Jf dependence and magnitude of the integral and differential cross sections are in good agreement, noticeable discrepancies exist for the angle dependence of the differential cross sections. In general, the calculated rotational rainbow structures are shifted towards larger scattering angles indicating that the anisotropy of the potential is overestimated in the fit to the ab initio points or in the ab initio calculation itself. For most states, we find the measured alignment moments to be in excellent agreement with the results of the calculation as well as with predictions of sudden models. Significant deviations from the sudden models are observed only for those fine-structure changing collisions which are dominated by forward scattering. Results of the full quantum calculation confirm the deviations for these states.

Journal Article↗

PubMed2004

[Zoonotic poxviruses].

In the last few years, the mass media and also scientists have been showing an increasing interest in poxviruses. What kind of infections can be found in animals and men today? The following review gives an overview on current taxonomy, properties, epidemiology, and diagnosis of zoonotic poxviruses.

Animals↗

PubMed2004

The beta-agonist clenbuterol in mane and tail hair of horses.

REASONS FOR PERFORMING STUDY: The beta2-agonist clenbuterol is commonly administered for therapeutic purposes in the horse, but its use an an anabolic agent is illegal. Clenbuterol can be detected in blood and urine for a relatively short period after administration and detection in hair could enhance the analytical range and be used to determine the history of clenbuterol application. HYPOTHESIS: That detection in mane or tail hair is possible over an extended period. METHODS: Four horses received 0.8 microg clenbuterol hydrochloride/kg bwt b.i.d. for 10 days. Four other horses were used as untreated controls. Blood, urine, mane and tail hair samples were taken on Day 0 (before) and 5, 10, 30, 35, 40, 60, 90, 120, 150 and 360 days after start of treatment. Gas chromotography/high resolution mass spectrometry (GC/HRMS) was developed for clenbuterol analysis: limit of detection was 0.2 pg/mg; intra-assay repeatability limit r = 0.06 (confidence level 95%); interassay repeatability limit r = 0.03 (confidence level 95%). Prior to treatment, clenbuterol was absent from all samples analysed. RESULTS: Clenbuterol was detectable as early as Day 5 in tail and mane hair of Segment 1 (0-20 mm from the roots) and was maximal on Day 90. However, as time progressed, shift into lower 20 mm segments was observed. On Day 360, the maximum concentration (up to 21 pg/mg) was located in Segment 13, i.e. 26-28 cm from roots of hair. Clenbuterol was not detectable in blood or urine after Day 30. Mane and tail hair results were very similar. CONCLUSIONS: The study showed that the beta-agonist clenbuterol can be found in mane and tail hair of horses after extended periods. POTENTIAL RELEVANCE: It will be possible to detect clenbuterol in breeding and show horses where anabolic drugs have been used illegally to improve conformation. This method may also be helpful to monitor therapeutic clenbuterol treatment.

Administration, Oral↗

PubMed2004

[Pyrido [3,2-b]indol-4-yl-amines--synthesis and investigation of activity against malaria].

Pyrido[3,2-b]indol-4-yl-amines--synthesis and investigation of activity against malaria Starting with 3-aminoindole-2-carboxylic acid ester 1 the annulated pyrido[3,2-b]indoles 6 and 8 were synthesized as key substances. The 4-chloropyridine derivative 8 reacted with the phenol Mannich bases 11 and the novaldiamine base 13, respectively, to yield the amodiaquine and cycloquine analogues 12 as well as the chloroquine analogue 14. The stability of the compounds 12 and 14 were proven by the half wave potentials measured by differential pulse voltammetry. Compounds 12 and 14 were tested for in vitro antimalarial activity using a chloroquine sensitive and a chloroquine resistant Plasmodium falciparum strain. The highest activity was shown by 12g with IC50 values of 50 nM and 38 nM, respectively. The in vivo activity of 12g was tested in Plasmodium vinckei infected mice resulting in ED50 values of 22 mg/kg and 26 mg/kg after intraperitoneal and oral administration, respectively.

Administration, Oral↗

PubMed2004

[[1]Benzofuro[3,2-b]pyridin-4-yl-amines - synthesis and investigation of activity against malaria].

The ethyl 4-chlorobenzofuro[3,2-b]pyridine-3-carboxylate (2) reacted with the hydrochlorides of the mono- and bis-phenol Mannich bases 3 to yield the amodiaquine and pyronaridine analogues 4. The chloroquine analogue 6 was formed by melting 2 with the novaldiamine base (5) in phenol. The most active compound 4c inhibited the growth of the malaria parasite Plasmodium falciparum with an IC50 of 500 nM.

Amines↗