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Biomedical subjects

J Baier

Publications and source records attributed to J Baier.

At least 19 recordsLinked to original sources

Epifluorescence, confocal and total internal reflection microscopy for single-molecule experiments: a quantitative comparison.

Epifluorescence, confocal and total internal reflection microscopy are the most widely used techniques for optical single-molecule experiments. Employing these methods, we recorded the emission intensity of the same single molecule as a function of the excitation rate under otherwise identical experimental conditions. Evaluation of these data provides a quantitative comparison of the signal-to-background ratios that can be achieved for the three microscopic techniques.

Journal Article↗

Structural aspects of metamagnetism in Ca2-xSrxRuO4: evidence for field tuning of orbital occupation.

The crystal structure of Ca(2-x)Sr(x)RuO(4) with 0.2 < or = x < or = 1.0 has been studied by diffraction techniques and by high resolution capacitance dilatometry as a function of temperature and magnetic field. Upon cooling in zero magnetic field, the crystal structure and the octahedra shrink along the c direction and elongate in the a and b planes, whereas the opposite occurs upon cooling at high field (x = 0.2 and 0.5). These findings yield evidence for an orbital rearrangement driven by temperature and magnetic field, which accompanies the metamagnetic transition at low temperature. The temperature and magnetic-field dependencies are found to be governed by the same energy scale.

Journal Article↗

Zero-field incommensurate spin-Peierls phase with interchain frustration in TiOCl.

We report on the magnetic, thermodynamic, and optical properties of the quasi-one-dimensional quantum antiferromagnets TiOCl and TiOBr, which have been discussed as spin-Peierls compounds. The observed deviations from canonical spin-Peierls behavior, e.g., the existence of two distinct phase transitions, have been attributed previously to strong orbital fluctuations. This can be ruled out by our optical data of the orbital excitations. We show that the frustration of the interchain interactions in the bilayer structure gives rise to incommensurate order with a subsequent lock-in transition to a commensurate dimerized state. In this way, a single driving force, the spin-Peierls mechanism, induces two separate transitions.

Journal Article↗

Different look at the spin state of Co(3+) ions in a CoO(5) pyramidal coordination.

Using soft-x-ray absorption spectroscopy at the Co L(2,3) and O K edges, we demonstrate that the Co3+ ions with the CoO5 pyramidal coordination in the layered Sr2CoO3Cl compound are unambiguously in the high spin state. Our result questions the reliability of the spin state assignments made so far for the recently synthesized layered cobalt perovskites and calls for a reexamination of the modeling for the complex and fascinating properties of these new materials.

Journal Article↗

Detection of interleukin-6 in maternal plasma predicts neonatal and infectious complications in preterm premature rupture of membranes.

The objective of this study is to determine if the detection of interleukin-6 (IL-6) in maternal plasma prior to delivery predicts neonatal and/or infectious complications in patients with preterm premature rupture of membranes. Patients with preterm premature rupture of membranes between 24 and 35 weeks' gestation were asked to participate in the study. Maternal blood was obtained prior to delivery. All patients received Ampicillin-sulbactam and steroids. IL-6 concentrations were determined by enzyme-linked immunoadsorbent assay (ELISA) using 50 mL of plasma assayed in duplicate. ELISA sensitivity was 18 pg/mL. Neonatal and infectious complications examined were respiratory distress syndrome, necrotizing enterocolitis, intraventricular hemorrhage, intra-amniotic infection, presumed neonatal sepsis, neonatal sepsis, and congenital pneumonia. Fifty-seven patients' plasma was analyzed. Thirty-five had positive plasma IL-6 prior to delivery. Twenty-seven patients had at least one neonatal complication with 24 (89%) being positive for IL-6. Of the 30 patients without complications, only 11 (37%) were positive (p = 0.0001, OR 13.8. 95% CI, 2.93-74.7). A subanalysis of patients who received a course of corticosteroids was performed and significance was maintained. Ten of 13 patients (77%) with neonatal complications had positive IL-6 compared with 40% without complications (p <or=0.01). Infectious morbidity occurred in 32 patients with 24 having positive IL-6 values (75%). Only 11 of 25 (44%) without infections were positive (p <or=0.03, OR 3.82, 95%, CI 1.09-13.0). The presence of IL-6 in the maternal plasma predicted patients with neonatal complications. These correlations persisted when the data were stratified for those patients who received corticosteroids. It also predicted infectious complications.

Adult↗

Exposure of hooded capuchin monkeys (Cebus apella cay) to a rabid bat at a zoological park.

On 27 May 1999, a big brown bat (Eptesicus fuscus) was discovered on an island exhibit at the Denver Zoo that contained a troop of 15 hooded capuchin monkeys (Cebus apella cay). The monkeys were attacking the bat when it was discovered. The bat was collected and humanely euthanatized without direct handling and submitted to the Colorado Department of Public Health and Environment Virology Laboratory for rabies evaluation. The monkeys had not been vaccinated against rabies virus. The next day, the laboratory confirmed that the bat was positive for rabies. The recommendations from the Colorado Department of Public Health and Environment and the Centers for Disease Control and Prevention were to euthanatize the monkeys or quarantine them and comply with the human nonvaccinated postexposure protocol. A 1-ml dose of a killed rabies vaccine was administered i.m. in the hip on each of days 2, 7, 12, 19, and 33 postexposure, and a single dose of human rabies immune globulin was administered i.m. 5 days postexposure. Blood was collected under anesthesia in order to evaluate the immune response after rabies vaccination from six monkeys 5 days postexposure, six monkeys 19 days postexposure (five of the six monkeys were the same monkeys bled 5 days postexposure), 15 monkeys 67 days postexposure, and 13 monkeys approximately 1 yr postexposure. All of the monkeys developed and maintained levels of rabies virus neutralizing antibody above 0.05 IU/ml by 67 days postexposure. Although a serologic titer of 0.05 IU/ml indicates an adequate human response after rabies vaccination, no similar information is available for nonhuman primates. To date, none of the monkeys has succumbed to rabies.

Animals↗

[Acute generalized cat scratch disease in myelodysplastic syndrome].

In patients with normal immunity, cat scratch disease typically develop a papule at the portal of entry and no other cutaneous features. A 73 year old male patient with a myelodysplastic syndrome developed generalized petechial, papular and, vasculitic skin lesions in association with cat scratch disease. After the diagnosis was established by identifying the causative organism in a lymph node biopsy, the patient was treated with erythromycin for three weeks resulting in progressive clearance of the skin lesions. Apart from the soluble IL-2 receptor, no other serologic inflammatory parameters were elevated. IgG antibodies against Bartonella henselae and Bartonella quintana increased only slightly during acute exacerbation of the disease, but significantly increased some months later. The diagnosis was established by the positive staining of the lymph node biopsy using the Warthin-Starry stain.

Administration, Oral↗

Induction of monocyte chemoattractant protein-1 by Mycoplasma hominis in respiratory epithelial cells.

BACKGROUND: Very small preterm infants who have genital mycoplasmas isolated from the trachea are at increased risk to develop bronchopulmonary dysplasia (BPD). The early stages of BPD are characterized by inflammation. Recruitment and activation of mononuclear cells in response to mycoplasmas may be important in the early stage of the disease. Lung epithelial cell production of monocyte chemoattractant protein-1 (MCP-1), a protein that attracts and activates mononuclear cells, could be critical in the regulation of mononuclear cell migration to the lung. METHODS: We examined the potential of Mycoplasma hominis (Mh) to induce MCP-1 gene expression and protein production in A549 cells, a pulmonary epithelial cell line with characteristics of type II cells. RESULTS: Live or heat-inactivated Mh induces MCP-1 mRNA and protein in a dose- and time-dependent manner. Stimulation of MCP-1 by Mh was not inhibited by 50 micrograms/mL of polymyxin B, interleukin (IL)-1ra, or neutralizing antibodies to IL-1 alpha, IL-1 beta, or tumor necrosis factor alpha (TNF-alpha). IL-1 alpha, IL-1 beta, and TNF-alpha were not detected in conditioned media of Mh-stimulated A549 cells. CONCLUSIONS: These data suggest that Mh may participate in the inflammatory component of BPD by directly inducing epithelial cell production of cytokines that recruit and activate mononuclear cells.

Bronchopulmonary Dysplasia↗

[Selective embolization of a bile leak after operative resection of an echinococcal cyst].

HISTORY AND ADMISSION FINDINGS: One year after an Echinococcus granulosa cyst had been resected in a 37-year-old woman she presented for follow-up. She was without symptoms and physical examination was unremarkable. INVESTIGATIONS: Sonography and computed tomography showed renewed growth of the cyst (6.5 cm diameter) in the VIth liver segment. The Echinococcus antibody titre was increased to 1:20 (normal 1:5). DIAGNOSIS, TREATMENT AND COURSE: An echinococcal cyst was again diagnosed and a pericystectomy with intrahepatic drainage performed. A bile leak developed postoperatively through an open bile duct at the operative site. This duct was selectively visualized by endoscopic retrograde choleangiography and its distal part embolized with 1.5 ml Histoacryl: there was no further bile leak. No relevant clinical side effects occurred. CONCLUSION: Selective embolization is a possible alternative to currently employed procedures for stopping bile leaks.

Adult↗

Interleukin-8 stimulates placental prostacyclin production in preeclampsia.

PROBLEM: Our purpose was to determine placental interleukin (IL)-8 production and its correlation with the prostacyclin production in normal and preeclamptic pregnancies and to evaluate the beneficial effect of IL-8 on prostacyclin production. METHOD OF STUDY: We determined 1) the in vitro production of IL-8 and prostacyclin by placental villous tissues from normal and preeclamptic pregnancies and 2) the production of prostacyclin by villous tissues from preeclampsia treated with recombinant human IL-8 (rhIL-8). IL-8 levels were measured by enzyme-linked immunosorbent assay and prostacyclin by radioimmunoassay of 6-keto PGF1alpha, the stable metabolite of prostacyclin. RESULTS: 1) Placental production of IL-8 and 6-keto PGF1alpha were significantly less in preeclampsia than in normal pregnancies, P<0.05. 2) Placental production of 6-keto PGF1alpha and IL-8 was significantly correlated in preeclampsia, P<0.01. 3) Placental tissues treated with IL-8 exhibited a concentration-dependent increase in 6-keto PGF1alpha production. CONCLUSIONS: Placental tissues from preeclampsia produce significantly less IL-8 than tissues from normal pregnancies, which correlates with decreased prostacyclin production. IL-8 improves placental prostacyclin production in preeclampsia.

6-Ketoprostaglandin F1 alpha↗

Induction of neutrophil chemoattractant cytokines by Mycoplasma hominis in alveolar type II cells.

Bronchopulmonary dysplasia (BPD) is a chronic lung disease of premature infants who are mechanically ventilated due to respiratory distress. The disease consists of an initial inflammatory influx of neutrophils to the lungs, followed by long-term chronic fibrosis of the lung tissue. The antigenic repertoire that initiates the inflammatory component of BPD has not been defined. Furthermore, the repertoire of cytokines responsible for attracting neutrophils to the lung and the mediators of pathogenesis in BPD have not been characterized. Mycoplasmas such as Mycoplasma hominis and Ureaplasma urealyticum have been isolated from the lungs of infants that developed BPD and yet have not been widely recognized as potential initiators of the inflammatory component of BPD. In the studies described here, we examined the ability of both viable and heat-killed Mycoplasma hominis to elicit type II epithelial cell production of cytokines that are chemotactic for polymorphonuclear leukocytes (PMNs), particularly interleukin-8 (IL-8) and epithelial cell-derived neutrophil-activating peptide (ENA-78). The results of these studies demonstrate that M. hominis and M. hominis antigen are potent stimulators of type II epithelial cell-derived IL-8 and ENA-78. Thus, these data strongly suggest that the presence of M. hominis in the lungs of premature infants may initiate the inflammatory component of BPD by inducing epithelial cell production of cytokines chemotactic for PMNs. Furthermore, these data suggest that the onset of the inflammatory component of BPD likely precedes, and is independent of, the recruitment and activation of alveolar macrophages.

Cell Movement↗

Salmonellosis in captive black rhinoceroses (Diceros bicornis).

Salmonellosis caused by Salmonella enterica subspecies arizonae (formerly known as Salmonella arizonae) was diagnosed in three of five captive black rhinoceroses (Diceros bicornis) at the Denver Zoological Gardens. Two of the three animals died despite supportive treatment. The other two rhinoceroses remained asymptomatic and were negative for Salmonella spp. after serial fecal cultures. The source for the salmonellosis was never identified.

Animals↗

[Mechanisms of action of intravenous immunoglobulins].

Intravenous immunoglobulins (IVIG) are now used to treat various diseases, including autoimmune diseases, systemic inflammatory diseases, allografts and for replacement therapy in the case of IgG deficiency. Only in some of the indications has the efficacy of this treatment been confirmed in large-scale studies. Also, in many cases the modes of action remain unclear. Principally, the following therapeutic strategies can be differentiated: Replacement treatment, blocking of the effector molecules, influencing of the cellular and humoral limbs of the immune defence system and interaction with cytokines. In certain CNS diseases, displacement of pathological immunoglobulins may be involved. It would be desirable to acquire more detailed knowledge about modes of action with the aim of using IVIG with greater specificity in the future.

Acute-Phase Reaction↗

A flow cytometric method for the detection of intracellular basic proteins in unseparated peripheral blood and bone marrow eosinophils.

Eosinophils and their basic proteins play a major role in allergic disease and methods are required to monitor their expression in clinical situations. In this article we describe a flow cytometric method for the detection of intracellular eosinophil cationic protein (ECP) and eosinophil peroxidase (EPO) in unseparated clinical samples. After fixation with parabenzoquinone and permeabilization with n-octyl-beta-D-glucopyranoside, the detection of intracellularly stored proteins was achieved using of monoclonal antibodies against ECP (EG1, EG2) and EPO in combination with an FITC-labeled second step antibody. Confocal microscopy was used to demonstrate the intracellular origin of the fluorescent signal. Fixation with parabenzoquinone was superior to a previously described protocol using paraformaldehyde, since it reduces non-specific binding of FITC to the basic proteins in eosinophils. Fixation and permeabilization do not alter the light scatter characteristics of eosinophils in contrast to other leukocytes and thus permit gating on eosinophils without prior purification. Furthermore, the procedure does not alter the detection of cell surface antigens on eosinophils and simultaneous measurements of surface antigens and intracellular proteins is possible. We have used different clinical samples (peripheral blood, bone marrow cells) to demonstrate differences in the expression of ECP and EPO. We conclude that the detection of intracellular eosinophil proteins by flow cytometry is a rapid, easy and semiquantitative procedure which may be used to study their expression in diseases where eosinophils are involved.

Antibodies, Monoclonal↗

[Intraindividual reproducibility of ultrasound detection of gastrobiliary motility parameters and CCK incretion after a standardized, liquid, fat-containing test meal].

AIM AND METHODS: Gastric emptying, antral mobility, fasting gallbladder volumes, gallbladder emptying rates, and CCK incretion following a standardized liquid fatty meal were investigated in 14 healthy young volunteers (seven women and seven men) on two separate study days. In the seven young women, taking oral contraceptives, one study day was in the oestrogen phase and the other in the gestagen phase of their menstrual cycle. RESULTS: There was good intraindividual reproducibility of the different sonographic gastrobillary motility parameters and the postprandial CCK incretion in both sexes (coefficients of reliability between 0.80 and 0.98). A significant effect of the menstrual cycle phase in young women was not evident. Instead of this a wide interindividual range of motility parameters, especially of gastric residual volumes in young women, could be obtained. There was no close correlation between gastric emptying rates or the amounts of the fat induced cholecystokinin incretion and gallbladder emptying rates, indicating the relevance of additional cholecystokinin-independent preduodenal mechanism for the regulation of physiological digestive gallbladder emptying.

Adult↗