Biomedical subjects

H Meyer

Publications and source records attributed to H Meyer.

At least 73 records · Page 4Linked to original sources

PubMed2000

Regulation of alpha(2A)-adrenoceptor expression by chronic stress in neurons of the brain stem.

Alpha(2)-Adrenoceptors are supposed to be important regulatory elements in responses to stress. Previous receptor binding studies in male tree shrews have shown that chronic psychosocial stress down-regulates binding sites for alpha(2)-adrenergic ligands in several brain stem nuclei. The aim of the present study was to quantify effects of chronic subordination stress on expression of the alpha(2)-adrenoceptor subtype A gene in identified neurons of the brain stem. We partially cloned the alpha(2A)-adrenoceptor cDNA of the tree shrew (1.22 kb) and localized receptor RNA expression in brain stem neurons by in situ hybridization using a 35S-labeled cRNA probe (1.06 kb). To identify neurons expressing receptor mRNA, brain sections were first immunocytochemically stained with antibodies against tyrosine hydroxylase, phenylethanolamine-N-methyltransferase, or glutamate, and then processed for in situ hybridization. Furthermore, expression of receptor-specific RNA was quantified in single neurons of animals which had been psychosocially stressed during 4 weeks and in unstressed controls. We found strong in situ hybridization in the noradrenergic neurons of the locus coeruleus, but only weak labeling of A2 neurons in the solitary tract nucleus and no labeling of A1 neurons in the caudal ventrolateral medulla. Adrenergic neurons in the solitary tract nucleus (group C2) did not express the alpha(2A)-adrenoceptor, and C1 neurons in the rostral ventrolateral medulla showed only a minor labeling by the in situ probe. In contrast, large glutamatergic neurons in the lateral reticular nucleus were strongly labeled by the probe. Chronic psychosocial stress reduced alpha(2A)-adrenoceptor RNA expression in locus coeruleus neurons (-24.0%), in solitary tract neurons (-31.0%), and in neurons of the lateral reticular nucleus (-18.8%). These findings show that stress not only decreases the expression of the alpha(2A)-adrenergic autoreceptor in the locus coeruleus but also of alpha(2A)-heteroreceptors in glutamatergic neurons.

Animals↗

PubMed2000

Habituation of the blink reflex in first-episode schizophrenia, psychotic depression and non-psychotic depression.

OBJECTIVE: Electrophysiological recording of the electrically elicited blink reflex is the most reliable method of investigating habituation of the startle reflex. The purpose of this study was to compare the habituation and the late R3-component of the blink reflex between control subjects (N=19) and first-episode patients with schizophrenia (N=17), psychotic depression (N=23), and severe non-psychotic depression (N=25). METHODS: The blink reflex was evoked by electrical stimulation of the supraorbital nerve, and the deficient habituation of the R2i-component was measured with a computer-assisted integral area measurement. Prefrontal executive function of the patients was assessed with the Wisconsin Card Sorting Test. Current psychiatric symptoms were assessed with the Brief Psychiatric Rating Scale, the Hamilton Depression Scale, the Positive and Negative Syndrome Scale, and the Calgary Depression Scale. RESULTS: Deficient habituation of the blink reflex and occurrence of the late R3 component were associated both with a previous diagnosis of psychotic disorder and with the presence of current psychosis. The sensitivity and specificity of the abnormal habituation of the blink reflex in detecting psychotic disorder were 0.50 and 0.80, respectively. The abnormalities of the blink reflex were not associated with psychotropic medication. In schizophrenic patients, defective habituation of the blink reflex was associated with negative and cognitive symptoms, and in depressive patients with the presence of delusions. CONCLUSIONS: The deficient habituation of the blink reflex and occurrence of the late R3 component seem to be both trait and state markers of a psychotic disorder. The results suggest that schizophrenia and psychotic depression share some common neurobiological mechanisms involved in the modulation of the startle reflex.

Adult↗

PubMed2000

Evaluation of a Yersinia adhesion gene (yadA) specific PCR for the identification of enteropathogenic Yersinia enterocolitica.

A total of 101 Yersinia enterocolitica strains was investigated with a PCR assay [Blais and Phillipe, Food Control, 6 (1995) 211-214] targeting the Yersinia adhesin gene (yadA) responsible for autoagglutination. Compared to the autoagglutination test the PCR assay has a specificity of 100% but a sensitivity of only 70%. This failure might be caused by the sequence heterogeneity of yadA.

Adhesins, Bacterial↗

PubMed2000

Effects of trovafloxacin on the IL-1-dependent activation of E-selectin in human endothelial cells in vitro.

E-selectin is an endothelial-specific surface protein, which is transiently expressed in response to inflammatory cytokines and plays an important role in the recruitment of leukocytes to the site of infection. The effect of two fluoroquinolones, ciprofloxacin (cipro) and trovafloxacin (trova), on the interleukin-1 (IL-1)-dependent activation of E-Selectin was studied on human umbilical vein endothelial cells (HUVEC) in vitro. Trova, at 80 microg/ml, affected the transient expression of E-selectin mRNA after pro-inflammatory stimulation with IL-1 leading to a sustained expression over 24 h. Surface expression of E-selectin remained upregulated after 24 h in a higher percentage of cells when they were activated in the presence of trova, as determined by flow cytometry analysis. Moreover, the concentration of shedded soluble E-selectin (sE-selectin) in the cell supernatant increased by 3.5 fold compared to those stimulated in the presence of cipro or without fluoroquinolones. Analogously, the antiproliferative effect of trova on endothelial cells was found to be more pronounced compared to cipro leading to an accumulation of cells arrested in G1-phase. These data provide evidence that accumulation of high concentration of trova in vivo in inflamed tissue might alter inflammatory responses.

Anti-Infective Agents↗

PubMed2000

Cowpox virus infection in an 11-year-old girl.

We describe an 11-year-old girl with a cowpox virus infection, who presented with a 14-day-old crusted, ulcerated nodule on the chin/neck and a 6-day-old eroded blister on the left leg. The girl lived in a rural environment, had close contact to several cats from the neighborhood, and had an atopic predisposition. The presence of orthopox virus in the lesion on the left leg was demonstrated by electron microscopy (negative staining, transmission electron microscopy) and virus isolation. Classification as a cowpox virus was determined by polymerase chain reaction (PCR), followed by restriction enzyme digestion of the PCR product.

Animals↗

PubMed2000

Identification of Yersinia enterocolitica within the genus Yersinia.

In this report we describe a PCR strategy for the unambigous identification of biochemically presumptive typed Yersinia (Y.) enterocolitica. A total of 269 isolates belonging to ten species of the genus Yersinia were investigated. In a first PCR only isolates classified as Y. enterocolitica (n = 113) gave rise to a specific amplification resulting in a sensitivity and a specificity of 100%. By sequencing the 269 amplicons of a second pan-Yersinia PCR spanning a distinct 16S rRNA gene region, 20 different sequence clusters could be identified within the genus. By this, Y. enterocolitica isolates of American and European origin could be distinguished safely and already described sequence clusters of the species Y. frederiksenii were confirmed. New 16S rRNA gene sequence clusters were detected for the species Y. frederiksenii, Y. intermedia, Y. mollaretii, Y. aldovae, Y. kristensenii, and Y. rohdei.

Animals↗

PubMed2000

Structure of the AAA ATPase p97.

p97, an abundant hexameric ATPase of the AAA family, is involved in homotypic membrane fusion. It is thought to disassemble SNARE complexes formed during the process of membrane fusion. Here, we report two structures: a crystal structure of the N-terminal and D1 ATPase domains of murine p97 at 2.9 A resolution, and a cryoelectron microscopy structure of full-length rat p97 at 18 A resolution. Together, these structures show that the D1 and D2 hexamers pack in a tail-to-tail arrangement, and that the N domain is flexible. A comparison with NSF D2 (ATP complex) reveals possible conformational changes induced by ATP hydrolysis. Given the D1 and D2 packing arrangement, we propose a ratchet mechanism for p97 during its ATP hydrolysis cycle.

Adenosine Diphosphate↗

PubMed2000

Yersinia enterocolitica 16S rRNA gene types belong to the same genospecies but form three homology groups.

The species Yersinia (Y.) enterocolitica consists of biochemically and serologically heterogeneous strains. A vernacular nomenclature divides these strains in 'European' and 'American' bioserotypes. We investigated six strains of each group by DNA-DNA hybridization, determination of G + C mol% content and sequence alignment studies. Based on different DNA-DNA hybridization values and the 16S rRNA gene sequences a division into two Yersinia enterocolitica subspecies is justified. We propose the names Yersinia enterocolitica subsp. enterocolitica for strains belonging to the 16S rRNA gene type represented by the Type strain ATCC 9610 and Yersinia enterocolitica subsp. palearctica for strains belonging to the 16S rRNA gene type of strain Y11 (DSMZ13030).

Animals↗

PubMed2000

Possible association of the short allele of the serotonin transporter promoter gene polymorphism (5-HTTLPR) with violent suicide.

There is abundant evidence that the serotonin (5-HT) system is modulating mood and several behavioural traits and that disturbances in the regulation of this system can be associated with severe behavioural malfunctions, as aggressive implusive and suicidal behaviour.1 Recently a functional polymorphism in the promoter region of the serotonin transporter gene (5-HTTLPR) was identified2 and the presence of one or two short alleles was associated with anxiety-related personality traits3 and several psychiatric disturbances, such as affective disorder4 or severe alcohol dependence.5 With respect to the importance of the 5-HT transporter in serotonergic transmission, we have genotyped the DNA of 58 Caucasian suicide victims (with unknown psychiatric diagnoses) and 110 healthy controls for the biallelic functional polymorphism in the 5-HTTLPR. We found a highly significant increased frequency of suicide victims being carriers of one or two short alleles (Fisher's Exact Test, two sided, P = 0.0003), which suggests that a genetically altered protein function within the serotonergic pathway might be involved in suicidality, independently from the clinical diagnosis.

Alleles↗

PubMed2000

A combination of different polymerase chain reaction (PCR) assays for the presumptive identification of Yersinia pestis.

A combination of four polymerase chain reaction (PCR) assays targeting the Yersinia pestis-specific plasmoidal genes of the fraction 1 capsular antigen and plasminogen activator/coagulase, the gene of the V antigen of the Yersinia virulence plasmid, and the chromosomal 16S rRNA gene was evaluated for the identification of Y. pestis isolates. All four assays were subjected to the same sample preparation technique, reagents and cycling conditions. Eighteen Y. pestis, 66 Y. pseudotuberculosis, 40 Y. enterocolitica strains, the type strains of the other Yersinia species, and 20 other pathogenic bacterial strains were investigated. By using the proposed combination of PCR assays all Y. pestis strains were identified correctly. The applicability of this combination of PCR assays was demonstrated by the detection of Y. pestis DNA in spiked tissues from Rattus norwegicus and fleas (Xenopsylla cheopis and Ctenocephalides spp.). As little as 60 genome equivalents were detected. This system is applicable for monitoring Y. pestis and its vectors in enzootic natural foci and in the diagnosis of plague in humans and animals.

Amino Acid Sequence↗

PubMed2000

Frequency and time course of pancreatic and extrapancreatic bacterial infection in experimental acute pancreatitis in rats.

BACKGROUND: Infectious complications in severe pancreatitis are the main factors determining clinical course and outcome. The taurocholate model for acute necrotizing pancreatitis was evaluated for frequency and time course of pancreatic and extrapancreatic bacterial infection. METHODS: Sixty-five male Wistar rats were divided into 5 groups of 13 animals each. Specimens for bacteriologic examination were taken, and pancreatitis was induced by intraductal infusion of 3% taurocholate under sterile conditions. Animals were killed 8, 16, 24, or 32 hours thereafter, and bacteriologic examination was performed. A control group of animals with intraductal infusion of 0.9% saline solution were killed after 32 hours. RESULTS: There was no significant pancreatic infection in the control group and in the 8-hour group (1 of 13 rats). Sixteen and 24 hours after induction of pancreatitis, infection and inflammation of the pancreas were found in 77% (10 of 13 rats), and after 32 hours pancreatic infection occurred in 69% (9 of 13 rats). Extrapancreatic bacterial infection after 16 hours occurred in the liver (62%), spleen (62%), and mesenteric lymph nodes (46%). Bacteria infecting the pancreas reflected the bacterial spectrum of the large bowel and terminal ileum before induction of pancreatitis (Escherichia coli [77%], Proteus [43%], Enterococcus [37%], and Staphylococcus [23%]). CONCLUSIONS: Pancreatic infection is an early and frequent finding in the taurocholate model of acute necrotizing pancreatitis. Infection occurs between 8 and 16 hours after induction of pancreatitis. The source of infecting bacteria seems to be the large bowel or the terminal ileum. We present a useful model of severe pancreatitis in which to study bacterial translocation, the further route of spread, and therapeutic approaches.

Acute Disease↗

PubMed2000

Field detection of Francisella tularensis.

A field investigation was undertaken following an outbreak of water-borne tularemia in Northern Norway. Francisella tularensis bacterial cellular components were analysed by rapid immunochromatography (RI)-testing, enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR). Water from 1 reservoir, fed from a rapid stream, tested negative. From another reservoir, 2 of a chain of 3 wells tested negative. The third well, at the end of the chain, contained lemming (Lemmus lemmus) carcasses and gave ample proof of F. tularensis contamination. We concluded that the origin of the outbreak was dead, infective lemming carcasses in the water sources. For the various sampling materials, the RI-test proved itself particularly handy and versatile, compared with the ELISA and the PCR.

Chromatography↗

PubMed2000

Isotope studies of hydrogen and oxygen in ground ice-experiences with the equilibration technique.

Equilibration technique suitable for a large amount of samples is described for hydrogen and oxygen isotope analyses of ground ice, especially ice wedges, including the sampling strategy and the analytical procedure as well as the calibration of the Finnigan MAT Delta-S mass spectrometer in June, 1999. Since for future analyses of ice wedges, a higher sampling resolution with limited sample volume is required, the limit of the equilibration technique for small water sample sizes of between 0.05 and 5 ml was checked. For water samples smaller than 1 ml, corresponding to a molar ratio [H2O]/[H2] of smaller than 0.994, a balance correction has to be applied. The experimental errors due to partial evaporation during evacuation, the balance calculation of the isotope equilibration process, the linearity as well as memory effects of the mass spectrometer for samples with large differences in delta18O and deltaD are tackled in this paper. In the polar regions of Northern Siberia without Late Pleistocene and Holocene glaciation, ground ice is used as an archive for paleoclimate studies. First results of stable isotope measurements on ice wedges clearly show a shift towards heavier isotopes and thus warmer winter temperatures as well as a change in the source of the precipitation between Late Pleistocene and Holocene. These results indicate the high potential of ground ice for paleoclimate studies.

Calibration↗

PubMed2000

Plasma rotation in a plasma generator

The plasma rotation in a linear magnetic configuration has been investigated by means of high-resolution Doppler-spectroscopy. The effects of external device parameters and ion mass as well as the radial profiles have been studied. A simple model, based on the conservation of the total angular momentum, explains the main empirically determined dependences of the average angular velocity. The results are compared with the common multifluid description developed for hollow cathode discharges.

Journal Article↗

PubMed2000

Crossover behavior in 3He and Xe near their liquid-vapor critical point

We present a detailed discussion of the crossover from mean-field to Ising critical behavior upon approach of the critical point, both for 3He and Xe. By combining different sets of experimental data, we are able to cover an unusually large temperature range on either side of the critical temperature T(c). Below T(c), we thus can make an accurate comparison with a recent calculation for the crossover of the coexistence curve. For the regime above T(c), an analysis of the compressibility demonstrates that the crossover regime in 3He is unexpectedly widened by a subtle interplay between quantum and critical fluctuations.

Journal Article↗

PubMed2000

Detection of Francisella tularensis in biological specimens using a capture enzyme-linked immunosorbent assay, an immunochromatographic handheld assay, and a PCR.

The early detection of Francisella tularensis, the causative agent of tularemia, is important for adequate treatment by antibiotics and the outcome of the disease. Here we describe a new capture enzyme-linked immunosorbent assay (cELISA) based on monoclonal antibodies specific for lipopolysaccharide (LPS) of Francisella tularensis subsp. holarctica and Francisella tularensis subsp. tularensis. No cross-reactivity with Francisella tularensis subsp. novicida, Francisella philomiragia, and a panel of other possibly related bacteria, including Brucella spp., Yersinia spp., Escherichia coli, and Burkholderia spp., was observed. The detection limit of the assay was 10(3) to 10(4) bacteria/ml. This sensitivity was achieved by solubilization of the LPS prior to the cELISA. In addition, a novel immunochromatographic membrane-based handheld assay (HHA) and a PCR, targeting sequences of the 17-kDa protein (TUL4) gene of F. tularensis, were used in this study. Compared to the cELISA, the sensitivity of the HHA was about 100 times lower and that of the PCR was about 10 times higher. All three techniques were successfully applied to detect F. tularensis in tissue samples of European brown hares (Lepus europaeus). Whereas all infected samples were recognized by the cELISA, those with relatively low bacterial load were partially or not detected by PCR and HHA, probably due to inhibitors or lack of sensitivity. In conclusion, the HHA can be used as a very fast and simple approach to perform field diagnosis to obtain a first hint of an infection with F. tularensis, especially in emergent situations. In any suspect case, the diagnosis should be confirmed by more sensitive techniques, such as the cELISA and PCR.

Antibodies, Monoclonal↗

PubMed2000

[Victor Hofmeister (1829-1994), Königl. Dresden Veterinary School--contributions to digestive physiology and animal nutrition].

Victor Hofmeister (1829-1894), a chemist, was active between 1862-1894 at the Tierärztliche Hochschule Dresden. His common work with Haubner, Siedamgrotzky and especially Ellenberger supplied basis information on digestibility of feestuffs (sheep, horses) about various clinical-chemical or toxicological questions, but particularly about the digestive physiology in horses, pigs, dogs and ruminants. The main results of the research group in Dresden outlast the last 100 years and represent valuable aspects for present knowledge in this field.

Animal Nutritional Physiological Phenomena↗

PubMed2000

Mousepox resulting from use of ectromelia virus-contaminated, imported mouse serum.

Mousepox was identified in a single mouse-holding room in early 1999 after a group of 20 CAF1/Hsd mice were inoculated SC with a killed murine spindle cell tumor line, S1509A. The cell line had been used without complications multiple times and was determined to be free of viral contamination on the basis of results of mouse antibody production testing. Of the 20 mice inoculated, 12 mice died by postinoculation day 8. Severe lymphoid and hepatic necrosis was observed in select mice subjected to histologic examination. Ballooning degeneration of epithelial cells with intracytoplasmic eosinophilic inclusion bodies was observed in the skin overlying the inoculation site of the single mouse from which this tissue site was evaluated. Presence of ectromelia virus was confirmed by use of immunohistochemical and polymerase chain reaction analyses, and the virus was isolated after serum, pooled from 5 of the index cases, was inoculated into an immune-naive mouse. Investigation into the source of virus contamination included inoculating mice with aliquots of various S1509A freeze dates; chemically defined media and supplements, including fetal bovine serum; and two lots of pooled commercial mouse sera, after heat inactivation at 56 degrees C for 30 minutes used as a medium supplement. One lot of pooled commercial mouse serum was identified as the source of ectromelia virus. This lot of serum was inadvertently used to feed S1509A cells that were subsequently inoculated into mice. We determined that the contaminated serum, which was purchased in late 1998, originated from China. The serum was imported into the United States as a batch of 43 L in early 1995. The serum was blended into a single lot and filtered (0.2 microm) before distribution to major suppliers throughout the country. The serum was sold or further processed to obtain a variety of serum-derived products. Because murine serum is generally sold in small aliquots (10 to 50 ml), we speculate that several thousand aliquots may have been derived from this batch of serum and, if inoculated into mice, would likely result in additional mousepox outbreaks.

Animals↗