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Biomedical subjects

E Meyer

Publications and source records attributed to E Meyer.

At least 37 records · Page 2Linked to original sources
PubMed2004

[Quality assurance in intensive care medicine. SARI-surveillance on antibiotic use and bacterial resistance in intensive care units].

Intensive care units (ICUs) are high risk areas for emergence and spread of multiresistant bacterial pathogens. In Germany, there are no representative epidemiological data on antibiotic resistance, prophylactic or therapeutic use of antibiotics in ICUs, or on the correlation between antibiotic use and emergence of resistance. Supported by the German Ministry of Science and Education, project SARI (Surveillance on antibiotic use and bacterial resistance in ICUs) started in 02/2000 and now includes data on antibiotic use and resistance rates in 35 medical, surgical and interdisciplinary ICUs. To date (2/2000-12/2002), a total of 939 participant months, 339,461 patient days and 452,282 defined daily doses (DDD) have been covered with a mean antibiotic usage density (AD) of 1,332 DDDs/1,000 patient days and resistance data on 31,189 isolates from ICUs. The design of the project and first results of SARI are presented. The epidemiological data of SARI form a basis for improved antibiotic and infection control management in ICUs (http://www.sari-antibiotika.de).

Anti-Bacterial Agents↗
PubMed2004

[SARI: surveillance of antibiotic use and bacterial resistance in German intensive care units. Correlation between antibiotic use and the emergence of resistance].

Intensive care units (ICUs) are considered to be high-risk areas for the emergence and spread of multiresistant bacterial pathogens. In Germany, there are no representative epidemiological data on antibiotic resistance, on the use of antibiotics in ICUs, or on the correlation between antibiotic use and the emergence of resistance. Project SARI (surveillance of antibiotic use and bacterial resistance in ICUs), which as a part of the epidemiological network Spread of Nosocomial Infections and Resistant Pathogens (SIR) is supported by the German Ministry of Science and Education, started in February 2000 and meanwhile includes data on antibiotic use and resistance rates in 38 medical, surgical, and interdisciplinary ICUs. To date (February 2000-June 2003), a total of 1142 months, 413,065 patient days, and 550,288 defined daily doses (DDDs in accordance with the WHO) have been covered with a mean antibiotic usage density (AD) of 1335 DDDs/1000 patient days and resistance data on 37,612 isolates from ICUs. Ciprofloxacin use and MRSA correlate significantly, as do imipenem use and the rate of imipenemresistant P. aeruginosa. The genodiversity of P. aeruginosa is lower in ICUs with high resistance rates and low use of imipenem than in ICUs with high resistance rates and high use. This is an indirect parameter of transmission of identical strains. The epidemiological data of SARI form a basis for improved antibiotic and infection control management in ICUs (http://www.sari-antibiotika.de).

Anti-Bacterial Agents↗
PubMed2004

Sex steroids and growth factors in the regulation of mammary gland proliferation, differentiation, and involution.

The mammary gland is subjected to major morphological and biochemical changes during the lactation cycle. It is therefore not surprising that this dynamic process is strictly controlled. The importance of the sex steroid hormones 17beta-estradiol and progesterone for normal development of the mammary gland was recognized several decades ago and has been unequivocally confirmed since. Furthermore, it is now also established that the influence of sex steroids is not restricted to mammogenesis, but that these hormones also control involution. Another important regulatory role is played by growth factors that have been shown to modulate survival (epidermal growth factor, amphiregulin, transforming growth factor alpha, insulin like growth factor, and tumor necrosis factor alpha) or apoptosis (tumor necrosis factor alpha, transforming growth factor beta) of mammary cells. However, the molecular mechanism underlying the influence of sex steroid hormones and/or growth factors on the development and function of the mammary gland remains largely unknown to date. Also scarce is information on the interaction between both groups of modulators. Nevertheless, based on the current indications compiled in this review, an important functional role for sex steroid hormones in the lactation cycle in co-operation with growth factors can be suggested.

Animals↗
PubMed2004

Nosocomial outbreak of norovirus gastroenteritis and investigation of ABO histo-blood group type in infected staff and patients.

The blood groups were analysed of staff and patients (N=45) infected during two nosocomial outbreaks of norovirus gastroenteritis at a German University hospital. Persons with O phenotype were significantly less affected than was expected from the normal distribution of blood group types in Southwest Germany (OR 2.45; 95% CI 1.22-4.95; P=0.01).

ABO Blood-Group System↗
PubMed2004

All-trans retinoic acid is increased in the acute phase-related hyporetinemia during Escherichia coli mastitis.

Blood vitamin A profiles, including concentrations of retinol and its active metabolite retinoic acid, were assessed during the peripartum period and during experimentally induced Escherichia coli mastitis in heifers. Serum retinol decreased in all animals in the immediate postpartum period and normalized within 1 wk after parturition. No significant changes were detectable in the concentrations of retinoic acid isomers during puerperium. Following intramammary E. coli infusion, all cows showed moderate symptoms of systemic disease besides the local signs of inflammation. The presence of a systemic acute-phase reaction was documented by fever, increase in serum amyloid A, and decrease in serum albumin. Retinol concentration in serum also decreased spectacularly during coliform mastitis, and the decline was clearly related to the timing of the acute-phase response. Moreover, a significant increase of all-trans retinoic acid, mirrored by a lowering of 13-cis retinoic acid, was detected during the same time period. The 9-cis isomer of retinoic acid was present in all samples, but it remained below the quantification limit. Results confirmed the decrease in serum retinol during the peripartum period of dairy cows. Furthermore, the study established that profound changes in vitamin A metabolism occur during the acute-phase reaction of coliform mastitis in heifers. The bovine infection model reproduced the acute phase-related hyporetinemia, as previously observed in humans and rats. In addition, all-trans retinoic acid was found to be the most abundant circulating acid isomer during mastitis, providing an indication for a possible key role of all-trans retinoic acid in the modulation of the immune response.

Acute-Phase Reaction↗
PubMed2004

Differential effects of steroids and retinoids on bovine myelopoiesis in vitro.

Pregnancy and parturition are associated with physiological changes caused by steroid hormones. Alterations in number, maturity, and function of polymorphonuclear leukocytes observed in dairy cows at parturition suggest a common causative relationship with steroid hormones. This study was designed to investigate the effects of progesterone, 17-beta-estradiol, and hydrocortisone on the proliferation of bovine progenitor cells. An in vitro culturing system was used, and colonies were scored after 7 d of incubation. At low concentrations, 17-beta-estradiol inhibited proliferation of granulocyte progenitor cells. Hydrocortisone reduced growth of granulocyte and monocyte colonies, whereas myelopoiesis was not altered by progesterone. Furthermore, we studied the effect of retinoids on colony formation of bovine bone marrow cells. All-trans- and 9-cis-retinoic acid stimulated growth of granulocyte colonies and inhibited proliferation of the monocyte lineage. The addition of the 13-cis-isomer also increased numbers of granulocyte colony-forming units. This study indicates that steroid hormones may be responsible for alterations in the bovine hematopoietic profiles observed in circulation during the postpartum period. White blood cells, especially polymorphonuclear leukocytes, which are derived from bone marrow, are an important first line defense against mastitis. Therefore, these effects of steroids might contribute to the increased susceptibility of dairy cows to Escherichia coli mastitis. We furthermore hypothesize that an important role might be attributed to retinoic acid in its regulation of bovine myelopoiesis. Modulation of myelopoiesis in favor of the granulocyte lineage during the acute-phase reaction may be an adaptive mechanism designed to increase the capacity of first-line defense to intramammary infections.

Animals↗
PubMed2004

Influence of 17beta-estradiol, progesterone, and dexamethasone on diapedesis and viability of bovine blood polymorphonuclear leukocytes.

The aim of the current study was to investigate whether polymorphonuclear leukocyte (PMN) diapedesis and viability are influenced by steroid hormones. Using an in vitro model with different types of cell layers (bovine mammary epithelial cells and fibroblasts), we investigate whether steroid hormone treatments (17beta-estradiol, progesterone, and dexamethasone) have an influence on the diapedesis capacity and viability of PMN. In addition, we studied apoptosis of PMN in the in vitro model and evaluated the influence of different types of cell layers and steroid hormone treatments on this process. A significant decrease in the number of viable PMN in the lower compartment of the in vitro model (i.e., number of migrated PMN x viability after migration) was found after 17beta-estradiol treatment, whereas no influence was detected after progesterone or dexamethasone treatment. The effect of 17beta-estradiol was not due to a lower viability before migration as none of the treatments caused a significant effect on the viability before diapedesis. This treatment effect was not influenced by endogenous 17beta-estradiol or progesterone levels before isolation because there was no correlation between these plasma levels and PMN diapedesis capacity or viability. Furthermore, migration through epithelial cells caused a significant decrease in viability of PMN due to increased apoptosis but not necrosis.

Animals↗
PubMed2003

Interaction potential and hopping dynamics governing sliding friction.

The friction force on a nanometer-sized tip sliding on a surface is related to the thermally activated hopping of the contact atoms on an effective atomic interaction potential. A general analytical expression relates the height of this potential and the hopping attempt frequency to measurements of the velocity dependence of the friction force performed with an atomic force microscope. While the height of the potential is roughly proportional to the normal load, the attempt frequency falls in the range of mechanical eigenfrequencies of the probing tip in contact with the surface.

Journal Article↗
PubMed2003

Direct determination of the energy required to operate a single molecule switch.

Using a noncontact atomic-force and scanning-tunneling microscope in ultrahigh vacuum, we have measured the switching energy of a single molecule switch based on the rotation of a di-butyl-phenyl leg in a Cu-tetra-3,5 di-tertiary-butyl-phenyl porphyrin. The mechanics and intramolecular conformation of the switched leg is controlled by the tip apex of the noncontact atomic-force microscope. The comparison between experimental and calculated force curves shows that the rotation of the leg requires an energy less than 100 x 10(-21) J, which is 4 orders of magnitude lower than state-of-the-art transistors.

Journal Article↗
PubMed2003

Expression of a plant-derived peptide harboring water-cleaning and antimicrobial activities.

Drinking water is currently a scarce world resource, the preparation of which requires complex treatments that include clarification of suspended particles and disinfection. Seed extracts of Moringa oleifera Lam., a tropical tree, have been proposed as an environment-friendly alternative, due to their traditional use for the clarification of drinking water. However, the precise nature of the active components of the extract and whether they may be produced in recombinant form are unknown. Here we show that recombinant or synthetic forms of a cationic seed polypeptide mediate efficient sedimentation of suspended mineral particles and bacteria. Unexpectedly, the polypeptide was also found to possesses a bactericidal activity capable of disinfecting heavily contaminated water. Furthermore, the polypeptide has been shown to efficiently kill several pathogenic bacteria, including antibiotic-resistant isolates of Staphylococcus, Streptococcus, and Legionella species. Thus, this polypeptide displays the unprecedented feature of combining water purification and disinfectant properties. Identification of an active principle derived from the seed extracts points to a range of potential for drinking water treatment or skin and mucosal disinfection in clinical settings.

Amino Acid Sequence↗
PubMed2003

Design of a surveillance system of antibiotic use and bacterial resistance in German intensive care units (SARI).

BACKGROUND: Data on antibiotic consumption and bacterial resistance are important for benchmarking, ensuring quality of antibiotic treatment and helping to understand the relationship between the use of antibiotics and the emergence of resistance. METHODS: The SARI project is an ecological study that has established laboratory-based surveillance in German intensive care units (ICU). Resistance rates of 13 sentinel pathogens are reported and certain alert organisms are sent for genotyping and retesting of antimicrobial resistance. RESULTS: The project, initiated in February 2000, now includes 35 ICUs generating a total of 266,013 patient days, 354,356 defined daily doses (DDD) and providing susceptibility data on 21,354 isolates. Pooled antibiotic usage density (AD = DDD/1,000 patient days) was highest for penicillins with lactamase inhibitor (AD 338.3) followed by quinolones (AD 155.5) and second-generation cephalosporins (AD 124.6). Total AD was calculated as 1,337 DDD/1,000 patient days. Resistance rates (RR) for laboratories testing according to the German Industrial Standard (DIN) were 19.3% for methicillin-resistant Staphylococcus aureus (MRSA), 9.5% for ciprofloxacin-resistant Escherichia coli and 25.4% for imipenem-resistant Pseudomonas aeruginosa. 40% of the laboratories did not identify the extended spectrum beta lactamase production of a Klebsiella pneumoniae strain. CONCLUSION: Focusing on German ICUs, the SARI surveillance system provides a concept that produces a benchmark for the link between antibiotic resistance and consumption.

Anti-Bacterial Agents↗
PubMed2003

Longitudinal study on the prevalence of benzodiazepine (mis)use in a prison: importance of the analytical strategy.

AIMS: This study evaluates the suitability of gas chromatographic-mass spectrometric (GC-MS) analysis to follow-up the extent of benzodiazepine (mis)use in a Belgian prison population and compares it to other analytical strategies (e.g. screening followed by confirmation of the positive samples). DESIGN AND PARTICIPANTS: From February to August 1998, 598 persons were jailed of which 188 (31.4% of the incoming detainees) volunteered to be screened. Urine samples (530 in total) were collected on the day of arrival and after 14, 30 and 90 days of imprisonment. MEASUREMENTS: All samples were screened by EMIT(R) for benzodiazepines and analysed subsequently by GC-MS. FINDINGS: EMIT(R) screening yielded 117 (22.1%) positive samples, a number which increased to 174 (32.8%) after GC-MS analysis. Of these 174 GC-MS positive samples, 119 (68.4%) contained one benzodiazepine while for the remaining samples multiple benzodiazepine (mis)use could be demonstrated. A significant increase in benzodiazepine (mis)use was indicated only from day 0 to day 14 based on the GC-MS results but not on the immunoassay results, even when the latter were complemented with GC-MS analysis of the positively screened samples. The GC-MS data also demonstrated that benzodiazepines are mainly (mis)used by subjects on benzodiazepine prescription as almost 50% of these subjects took additional non-prescribed benzodiazepines. During GC-MS analysis other drugs were co-extracted unintentionally and chromatographed and 23.9% of the volunteers were positive for illegal drugs on the day of arrival. CONCLUSION: Immunoassay results yield an underestimation of the problem of benzodiazepine (mis)use in prison due to the high false negative rate. GC-MS analysis of all samples therefore is the recommended strategy for this type of longitudinal study as it yields more correct and detailed information than the immunoassay results.

Belgium↗
PubMed2003

Sympathoadrenal and immune system activation during the periparturient period and their association with bovine coliform mastitis. A review.

Increased incidence of clinical mastitis in high-yielding cows during early lactation has been attributed to a depressed functional capacity of the immune system. Sympathoadrenal factors are known to play an important role in modulating the host susceptibility and resistance to infectious diseases. Of primary importance in combating acute intramammary infections are polymorphonuclear leukocytes (PMN), as they represent one of the early lines of immunological defense. The release of stress hormones at parturition and during the first weeks of lactation has been proposed to partly contribute to the impaired function of PMN. Here, we summarize the current understanding of the stress-induced peripheral effectors, i.e. the limbs of the sympathetic system and the hypothalamic-pituitary-adrenal axis, on PMN function around parturition and during coliform mastitis. The questions as to whether and how stress induced secretion of glucocorticoids and catecholamines might affect the lactating dairy cow's udder health will be addressed.

Animals↗
PubMed2003

L-selectin and beta2-integrin expression on circulating bovine polymorphonuclear leukocytes during endotoxin mastitis.

The aim of this in vivo study was to examine the effect of intramammarily administered endotoxin (lipopolysaccharide, LPS) on the expression of L-selectin (CD62L) and the beta2-integrin subunits CD11b and CD18 on circulating bovine PMN. Six early lactating cows were infused with Escherichia coli LPS. The adhesion molecules under study were stained at the cell surface and analyzed flow cytometrically. In addition, some of the clinical parameters associated with adhesion molecule mobilization such as fever, blood cortisol levels, somatic cell count (SCC), and total and differential blood leukocyte count were measured. In analogy with observations during clinical coliform mastitis, a progressive decrease of CD62L expression levels was observed early after LPS infusion, concomitantly with a continuous rise of CD11b and CD18 density. However, no correlation was found between the kinetics of CD11b and CD18 density. The initial changes in adhesion molecule expression paralleled the decrease in blood PMN numbers, together with the increase in rectal temperature, cortisol levels, SCC, and number of circulating immature PMN. In conclusion, intramammarily administered LPS seems to play an important role in modulating adhesion receptor expression on circulating bovine PMN. Interestingly, in contrast to coliform mastitis, the net CD18 variation is not principally influenced by CD11b upregulation during endotoxin administration. The knowledge of adhesion molecule kinetics in relation to the different parameters evaluated in the present study contributes to an improved understanding of the inflammatory reaction.

Animals↗
PubMed2002

Abrasive wear on the atomic scale.

A scanning force microscope in ultrahigh vacuum has been used to realize and detect atomic-scale abrasion on KBr(001). The continuous time evolution of the lateral force under scratching reveals that the wear mechanism is due to the removal and the rearrangement of single ion pairs. The debris is reorganized in regular terraces with the same periodicity and orientation as the unscratched surface, as in local epitaxial growth. The applied load has a strong influence on the abrasive process, whereas the scan velocity is less relevant.

Journal Article↗
PubMed2002

Effect of enrofloxacin treatment on plasma endotoxin during bovine Escherichia coli mastitis.

OBJECTIVE AND DESIGN: To investigate the effect of enrofloxacin on endotoxin resorption during bovine Escherichia coli mastitis. ANIMALS: 12 healthy early post partum Holstein cows. TREATMENT: Mastitis was induced by intramammary infusion of 10(4) cfu E. coli P4:032. Six cows were treated twice according to the usual enrofloxacin therapy: 5 mg/kg enrofloxacin 1) intravenously at 10 h and 2) subcutaneously at 30 h after challenge. The other 6 cows served as non-treated controls. METHODS: Blood and milk samples were collected at several time points after challenge. LPS in plasma was quantified using the limulus amoebocyte lysate (LAL) assay. The somatic cell count (SCC) and cfu of milk samples were also analysed. RESULTS: Occasional LPS peaks were detected in the plasma of 2 control cows at 6 h post-challenge and of 1 enrofloxacin-treated cow at 10 h post-challenge (P < 0.01 and P < 0.05, respectively, in comparison with time 0), just before enrofloxacin treatment. After enrofloxacin treatment, no significant LPS amounts were detected in the plasma of treated cows, but neither in the control cows. CONCLUSION: During induced coliform mastitis, LPS resorption in plasma occured only sporadically and within 10 h post-challenge. Whereas enrofloxacin treatment clearly limited bacterial growth in milk, significant effects on LPS resorption could not be detected. This suggests that enrofloxacin treatment of E. coli mastitis is predominantly beneficial by its bactericidal activity and is not associated with enhanced resorption of endotoxins.

Animals↗