Regulation of expression of chemokine receptor BLR1/CXCR5 during B cell maturation.
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Animals↗
Biomedical subjects
M Lipp
Publications and source records attributed to M Lipp.
A lymphoid tissue-specific receptor, EDG6, with potential immune modulatory functions mediated by extracellular lysophospholipids.
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Adjuvants, Immunologic↗
Recommendations for uniform reporting of data following major trauma--the Utstein Style. An International Trauma Anaesthesia and Critical Care Society (ITACCS) initiative.
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Data Collection↗
Downstream activation of a TATA-less promoter by Oct-2, Bob1, and NF-kappaB directs expression of the homing receptor BLR1 to mature B cells.
The chemokine receptor, BLR1, is a major regulator of the microenvironmental homing of B cells in lymphoid organs. In vitro studies identify three essential elements of the TATA-less blr1 core promoter that confer cell type- and differentiation-specific expression in the B cells of both humans and mice, a functional promoter region (-36 with respect to the transcription start site), a NF-kappaB motif (+44), and a noncanonical octamer motif (+157). The importance of these sites was confirmed by in vivo studies in gene-targeted mice deficient of either Oct-2, Bob1, or both NF-kappaB subunits p50 and p52. In all of these animals, the expression of BLR1 was reduced or absent. In mice deficient only of p52/NF-kappaB, BLR1 expression was unaffected. Thus our data demonstrate that BLR1 is a target gene for Oct-2, Bob1, and members of the NF-kappaB/Rel family and provides a link to the impaired B cell functions in mice deficient for these factors.
Animals↗
EDG6, a novel G-protein-coupled receptor related to receptors for bioactive lysophospholipids, is specifically expressed in lymphoid tissue.
EDG receptors constitute a novel subfamily of G-protein-coupled receptors displaying a heterogeneous expression pattern. It was shown recently that the four members of this family thus far identified can bind lysophospholipids or lysosphingolipids as ligands. Here we report the identification and characterization of EDG6, a novel member of the EDG receptor family, isolated from in vitro differentiated human and murine dendritic cells. EDG6 is specifically expressed in fetal and adult lymphoid and hematopoietic tissue as well as in lung. The expression pattern of edg6 is strongly conserved in human and mouse. The human edg6 gene was mapped to chromosome 19p13.3 at the D19S120 marker. Considering the lymphoid-specific expression pattern of edg6 and the strong identity to the phospholipid-binding EDG receptor family, we propose that EDG6 may also act as a receptor for a lipid-derived ligand. Because of the known mitogenic and chemotactic activity of bioactive lipids, we believe that EDG6 may play an essential role in lymphocyte cell signaling.
Amino Acid Sequence↗
Intracellular and surface expression of the HIV-1 coreceptor CXCR4/fusin on various leukocyte subsets: rapid internalization and recycling upon activation.
We describe the expression and regulation of the HIV-1 coreceptor CXCR4/fusin. Using anti-CXCR4 mAb, we demonstrate that this chemokine receptor is highly expressed on neutrophils, monocytes, B cells, and naive T cells among peripheral blood cells. In secondary lymphoid organs CXCR4 was found to be expressed on B cells. However, individual variations with regard to surface expression could be observed on T cells. Expression of the receptor is not confined to the cell surface, as large amounts of intracellular stores can be found on various leukocytes. Upon activation with phorbol esters the amount of cell surface-expressed CXCR4 on lymphocytes increases twofold within 30 s before it is completely down-regulated within the next 2 min. Incubation of leukocytes with stroma derived factor-1alpha, the natural ligand for CXCR4, induces down-regulation of up to 60% of surface-expressed receptors in a pertussis toxin-insensitive manner. Interestingly, receptor cross-linking caused by incubation of cells with anti-CXCR4 mAb triggers receptor trafficking, in that the receptor is rapidly internalized and recycled to the cell surface. Therefore, receptor internalization and recycling may regulate the functional interaction of the receptor with envelope proteins during an initial step of HIV-1 infection.
3T3 Cells↗
[Quality of cardiopulmonary resuscitation by dentists in dental emergency care].
The crucial factor deciding the success of cardiopulmonary resuscitation is a sufficient oxygen supply. At about 4 min after cardiac arrest, cerebral death results because of hypoxia, and cardiopulmonary resuscitation has to be started regardless of the pathogenesis of the cardiac arrest. The purpose of the study was to assess the application of guidelines for cardiopulmonary resuscitation by participants at a dental surgery congress (n = 96) and to evaluate previous knowledge in cardiopulmonary resuscitation and knowledge after instruction. The present study was based on the standards and guidelines for cardiopulmonary resuscitation issued by the American Heart Association. The group was divided into four groups of doctors experienced or inexperienced in clinical emergencies or with dummies. For the study the Skillmeter-ResusciAnne (Laerdal, Stavanger, Norway) was used, which has automatic data recording. After analysis of the individual errors, the success of new instruction was assessed. Good previous knowledge was registered, particularly with respect to checking respiration and hyperextension of the head (67.7%), primary insufflation (93.8%), closed-chest cardiac massage (99%) and correct compression rate (68.4%). The participants demonstrated post-instruction improvement in all subdivisions except in the group without practice on dummies (primary insufflation: from 94.4 to 88.9%; correct order of checking consciousness and respiration, primary insufflation, the carotid pulse and closed-chest cardiac massage: from 22.2 to 5.6%). Good results with marked improvements in the second passage were achieved in checking consciousness and the carotid pulse, closed-chest cardiac massage and correct implementation of compression. The participants were, however, found to be in need of further education and training in diagnostics and certain cardiopulmonary resuscitation measures. Knowledge should be improved concerning recognition of the emergency (42.7%), checking the carotid pulse (22.9%), the correct order of primary insufflation and closed-chest cardiac massage (9.4%), correct implementation of compression (21.8%) and ventilation (36.4%), and the correct ratio of compression and ventilation (21.9%). Regular courses should be targeted at these specific aspects.
Anesthesia, Dental↗
Abnormal expression of the B-cell homing chemokine receptor BLR1 during the progression of acquired immunodeficiency syndrome.
The putative chemokine receptor BLR1 has been identified as the first G-protein-coupled receptor involved in B-cell migration and in microenvironmental homing to B-cell follicles and to germinal centers. In healthy individuals, expression of BLR1 is restricted to all mature recirculating B cells and to a subpopulation of T-helper memory cells. In the present study, we analyzed the distribution of BLR1 on defined lymphocyte subsets during the progression of acquired immunodeficiency syndrome. It is shown that the proportion of T-helper memory cells coexpressing BLR1 continuously decreases during the infection, whereas a high proportion of gamma/delta T cells expressing BLR1 can be found in peripheral blood. The latter subpopulation is restricted to lymphoid tissues in healthy individuals. Most interestingly, in 75% of all human immunodeficiency virus (HIV)+ individuals, peripheral blood B cells were identified as not expressing BLR1 and phenotypically resembling germinal center cells of lymphoid tissue. Using BLR1 as a marker molecule, this study identifies peripheral blood lymphocytes in HIV+ individuals that are usually restricted to lymphoid tissue in healthy individuals. Because HIV infection is active in lymphoid tissue even at the clinically latent stage, aberrant expression of the B-cell homing chemokine receptor BLR1 might be an early indicator for the onset of destruction of lymphoid tissue.
Acquired Immunodeficiency Syndrome↗
Analyzing cytotoxic T lymphocyte activity: a simple and reliable flow cytometry-based assay.
A flow cytometry-based assay for analyzing cytotoxic T lymphocyte (CTL) activity is presented. This new approach is characterized by easy handling, the generation of highly reproducible data sets and is not dependent on the use of radioactivity. Before exposure to primed CTL effector cells the target cells were labeled with the green fluorescent dye DiO18(3) which is incorporated stably into the cell membrane. After a 4-h incubation period, samples were counterstained with the red fluorescent nuclear dye propidium iodide in order to permit discrimination between live and dead cells within both cell populations. The assay has been used to quantitate CTL effector activity against allogeneic lymphoblasts. Results derived from this novel flow cytometry assay show an excellent correlation (r = 0.988) with data obtained using the standard 51chromium release assay. An additional advantage of the assay is that freshly prepared splenocytes may be used as target cells because culturing and activation of target cells is no longer required. The results demonstrate that the fluorescent dyes DiO18(3) and propidium iodide in combination with flow cytometry permit accurate analysis of cytotoxic T cell activity.
Animals↗
The promoters for human and monkey poliovirus receptors. Requirements for basic and cell type-specific activity.
The cellular receptors for poliovirus (PVR) are glycoproteins belonging to the immunoglobulin superfamily. Functional receptors for poliovirus are only expressed by primates; known rodent homologues lack the ability to bind virus due to amino acid differences. Human poliovirus infections are targeted to the gastrointestinal tract and, rarely, to motor neurons in the central nervous system. Available evidence suggests that poliovirus uses only one cellular receptor, implying that the tissue tropism of poliovirus is likely to be related to the expression of the human PVR (hPVR). However, low levels of expression of hPVR-specific mRNAs can be detected in many human tissues other than the apparent target cells. The nonpathogenic function of hPVR is unknown. For a study of the transcriptional control of hPVR expression, we have isolated and characterized the promoter of the hPVR gene. Deletion analysis defined an approximately 280 base pair minimal promoter fragment that: 1) lacks TATA- and CAAT-like elements, 2) is distinguished by a high GC content, and 3) promotes transcription at multiple start sites. The pattern of activity caused by transfection of serial 5'- and 3'-promoter deletions is almost identical in HEp2, HeLa, COS-1, and mouse L929 cells, indicating a similar transcriptional regulation of the hPVR promoter in these cell lines. However, on transfection of Raji cells, a Burkitt's lymphoma cell line harboring a transcriptionally inactive hPVR gene, all promoter reporter constructs tested exerted only residual activity. These results suggest that the cis-element(s) governing cell type-specific hPVR expression resides in the minimal promoter region. We also report the sequences of the promoters of two monkey homologues to hPVR (AGMalpha1 and AGMalpha2). Transcripts encoding the monkey poliovirus receptors originate from a region analogous to that identified for hPVR transcripts.
Animals↗
[Anesthetic management in pheochromocytoma].
Consequent preoperative alpha-receptor blockade, as well as improved surgical technique, anaesthetic management and monitoring have reduced perioperative mortality below 3%. Nevertheless, serious problems are still to be expected during the resection of "complicated" pheochromocytoma. "Complicated" in this context means one or more of the following conditions: missing preparation, severe technical surgical difficulties (e.g. location in the liver), concomitant disorders (e.g. coronary arterial disease), pregnancy and/ or great consequential damages (e.g. cardiomyopathia). Therapy of hemodynamic crisis during "complicated" resection of pheochromocytoma requires differentiated pharmacological combinations considering concomitant disorders. For instance multiple various combinations of phenoxibenzamine, natriumuitropussid, adenosine, magnesiumsulphate, esmolol, diltiazem have been used successfully in concomitant coronary art disease. Absolute preferences are not established. Similarly in the anaesthetic management, a determination of a preferred procedure is still missing. All anaesthetic possibilities should be used carefully directed with two aims: first minimise indirect release of catecholamines through effective vegetative damping and prevention of stress; second to support therapy of hemodynamic crises through ingenious use of effect and side effects of the anaesthetic drugs. Experiences and excellent cooperation between surgery, endocrinology and anaesthesiology are essential for successful prevention of perioperative complications.
Adrenal Gland Neoplasms↗
A putative chemokine receptor, BLR1, directs B cell migration to defined lymphoid organs and specific anatomic compartments of the spleen.
We describe the phenotype of gene-targeted mice lacking the putative chemokine receptor BLR1. In normal mice, this receptor is expressed on mature B cells and a subpopulation of T helper cells. Blr1 mutant mice lack inguinal lymph nodes and possess no or only a few phenotypically abnormal Peyer's patches. The migration of lymphocytes into splenic follicles is severely impaired, resulting in morphologically altered primary lymphoid follicles. Furthermore, activated B cells fail to migrate from the T cell-rich zone into B cell follicles of the spleen, and despite high numbers of germinal center founder cells, no functional germinal centers develop in this organ. Our results identify the putative chemokine receptor BLR1 as the first G protein-coupled receptor involved in B cell migration and localization of these cells within specific anatomic compartments.
Animals↗
[Quality assessment of continuing medical education].
Medical performance is subject to quality control. Continuous advanced training (CAT) and continuous medical education (CME) are essential, and quality must be checked and assured: structure (contents, organizational form, framework, term, demands on teachers), process (term of the CAT, interaction between teachers and participants) and results (satisfaction and acceptance, increased knowledge, influence on medical treatment, improvement of the success rate of medical treatment. In emergency medicine one must differentiate between the necessity for CAT (e.g., certified proof required for working as an emergency physician) and a desire for CME (the individual task of the physician). The diversity of forms of CAT/CME reflects the different individual requirements. Using the new German guidelines to obtain qualification as an emergency physician, "Fachkundenachweises Rettungsdienst" offers measures for quality assessment and assurance can be obtained. STRUCTURE QUALITY: The recommendations for obtaining the "Fachkundenachweis Rettungsdienst" which have been valid until now date from the year 1983 and were set fourth explained very differently in the individual countries medical boards. This led to problems in the comparability of the essential CAT. The quality of the structure has now been improved by establishing new minimum requirements for clinical activity, specification of particular knowledge, number of supervised calls for the emergency car as well as participation in interdisciplinary CAT courses, dealing with general and special aspects of emergency medicine. The aim of these measures is not the (senseless) regimentation of CAT training measures, but the qualified transfer of specific medical knowledge and treatment guidelines. PROCESS QUALITY: On qualifying, hardly any physician has any didactic and/or rhetorical education; the physician must make a personal effort to obtain a qualification of this kind. Conventional and commonly practised forms of learning must therefore be set aside in favour of modern teaching methods (e.g. problem-orientated learning). This will lead to a better acceptance of CAT/CME measures. It is essential for the process quality that the teachers' education meets the following requirements: relevant knowledge of preclinical emergency medicine, rhetorical and didactic abilities, employment of relevant teaching techniques, flexibility in presentation, extensive experience in emergency medicine as well as enthusiasm for high-quality education. RESULT QUALITY: Questionnaires can be used to evaluate the satisfaction and acceptance of the participants, as well as their rating of individual speakers. The results are decisive for planning future CAT/CME measures. The transfer of knowledge can be estimated at the end of advanced training by questionnaire. However, this makes allowance for previous knowledge/skills and how much is forgotten. The influence of advanced training on further medical treatment can be seen in the quality of a given CAT/CME measure, but not in the success rate of medical treatment. The result desired can only be achieved by linking all system components of medical quality control and assurance. Advanced training provides a fundamental contribution to this end.
Education, Medical, Continuing↗
[Movement of the temporomandibular joint during tracheal intubation].
Laryngoscopy causes temporary postoperative dysfunction of the temporomandibular joint (TMJ): during iatrogenic TMJ manipulation in anaesthetised patients, the TMJs have lost the protection afforded by the tone of the surrounding muscles. Thus far, the exact type and extent of TMJ movements have not been known. The purpose of this study was to develop a method to visualise and assess TMJ movements during intubation by means of electronic axiography, a diagnostic monitor of TMJ movements used in dentistry: registration of the hinge axis (HA) as an equivalent of the condylar paths on extra-oral sagittaly mounted, parallel plates. The HA is individually defined in each patient by the pure, rotating TMJ movement during initial mouth opening (no farward gliding of the condyles, incisor distance up to 10 mm). The parallel plates are placed in the TMJ region in the skull-mounted plate bow: both registration tips ("drawing" the HA tracings on the electronic plates) are connected to the mandible by a face bow, paraocclusally fixed to the teeth. The face bow is individually shaped for each patient to allow mask ventilation and free movement of the laryngoscope during intubation. HA tracings are registered and calculated for both sides independently every 24 ms with the SAM/Klett system and presented on sagittal and frontal projections. In the operating theatre, the active mouth-opening traces (MOT) are registered first and the passive endotracheal intubation traces (EIT) after induction of anaesthesia (same head position). With informed consent and approval by the ethics committee of the Landesärztekammer Rheinland Pfalz. 40 male patients (ASA I. Mallampati I, limb surgery) were randomly allocated to four groups (n = 10 each). OS: Oral intubation, suxamethonium (1.5 mg/ kg); OV: Oral intubation, vecuronium (0.1 mg/kg); NS: Nasal intubation, suxamethonium (1.5 mg/kg); and NV: Nasal intubation, vecuronium (0.1 mg/kg). Intubation was performed 100 s after injection of the relaxant. Pre- and postoperatively (every 24 h over 3 days, in case of positive findings longer) recorded were: active movements of the mandible (maximal mouth opening/ max. laterotrusion); dysfunction of the TMJ; and pain sensation in the TMJ (Helkimo rating). MOTs and EITs were recorded and analysed with the system described and typical EIT patterns were identified: bland, clinically uneventful intubations (n = 7), massive distraction and laterotrusion of the EIT compared to the MOT (n = 24), and blocked or limited TMJ movements resulting in intubation problems (n = 1). With the method presented, TMJ movements could be visualised during endotracheal intubation for the first time. It can be used to assess techniques, routes, and instruments for intubation as well as to evaluate potential traumatising movements during endotracheal intubation.
Adult↗
[The transillumination technique. An alternative to conventional intubation?].
The technique of light-guided intubation is based on the principle that a source of light brought into the trachea results in clearly visible and defined transcutaneous illumination, while no illumination can be observed with the light source in the oesophagus (Fig. 1-7). The Trachlight is a reintroduced instrument for this alternative intubation technique. The essential developments are: a length-adjustable stylet with a removable internal metal wire, a brighter light source, a stable handle with tight fixation of the endotracheal tube, and a time-dependent warning device to avoid extended intubations. One hundred twenty patients (Mallampati I. ASA I-III) were included in the study (conventional intubation [group KL, n = 60]. Trachlight intubation [group TT, n = 60]. The goals of the investigation were to examine the handling, application, problems, limitations, and possible indications of the method. The recorded parameters were: number of intubation attempts: course and duration of intubation; complications; and difficulties. In 40 patients (20 in each group) the indication for invasive blood pressure measurement was given due to the surgical procedure, and circulatory parameters were recorded at defined moments during the intubation course. In group KL 55 patients were intubated in the attempt, 4 on the second, and 1 on the third (mean duration 23.6 +/- 10.4 s, range 12-60 s). Complications were: unilateral intubation (3 patients), bradycardia (2), asystole (1) and soft-tissue injury (1). Of the 60 patients in group TT. 54 were intubated successfully, the mean time needed being 29.9 +/- 14.8 s (range: 6-61 s). The remaining 6 were then intubated by the conventional method. Positive results in group TT included: easy handling and application, no injury to soft tissues or teeth, and invariably correct placement of the tube. Problems included: sufficient transillumination was achieved only after (entire) dimming of the room, insufficient control over the distal end of the tube due to an unfixed metal wire, unintentional switching off of the light while with-drawing the metal wire, difficulties in withdrawing the metal wire (too strong fixation), as well as disturbing effects of the warning device (blinking of the light 30 s after switching on). Reasons for the 6 intubation failures were introduction of the instrument into the oesophagus despite a supposed correct position, impossibility of correct placement in a patient with an extremely large goiter, and insufficiently clear transillumination in 3 extremely obese patients. The cardiovascular parameters showed no changes during laryngeal manipulation; a clear rise in heart rate and blood pressure was recorded, however, when the tube was inserted into the trachea. The cardiovascular parameters during conventional intubations were similar. The light-guided intubation technique can be regarded as a further alternative for airway management, due to the described improvement of the instrument. The indication for the technique is given in patients in whom no difficulty with intubation is expected, to avoid soft tissue damage and traumatising temporomandibular joint movements. Preclinical use may be limited due to environmental brightness. In patients with expected difficult airway management, fiberoptic intubation will remain the method of choice.
Esophagus↗
The E2F transcription factor activates a replication-dependent human H2A gene in early S phase of the cell cycle.
Histone gene expression is restricted to the S phase of the cell cycle. Control is mediated by a complex network of sequence-specific DNA-binding factors and protein-protein interactions in response to cell cycle progression. To further investigate the regulatory functions that are associated at the transcriptional level, we analyzed the regulation of a replication-dependent human H2A.1-H2B.2 gene pair. We found that transcription factor E2F binds specifically to an E2F recognition motif in the H2A.1 promoter region. Activation of the H2A.1 promoter by E2F-1 was shown by use of luciferase reporter constructs of the intergenic promoter region. Overexpression of the human retinoblastoma suppressor gene product RB suppressed E2F-1 mediated transcriptional activation, indicating an E2F-dependent regulation of promoter activity during the G1-to-S-phase transition. Furthermore, the activity of the H2A.1 promoter was also downregulated by overexpression of the RB-related p107, a protein that has been detected in S-phase-specific protein complexes of cyclin A, E2F, and cdk2. In synchronized HeLa cells, expression of luciferase activity was induced at the beginning of DNA synthesis and was dependent on the presence of an E2F-binding site in the H2A.1 promoter. Together with the finding that E2F-binding motifs are highly conserved in H2A promoters of other species, our results suggest that E2F plays an important role in the coordinate regulation of S-phase-specific histone gene expression.
Animals↗
Expression of the chemokine receptor BLR2/EBI1 is specifically transactivated by Epstein-Barr virus nuclear antigen 2.
In our attempt to identify chemokine receptors that are related to Burkitt's lymphoma receptor 1 (BLR1) and are expressed in activated lymphocytes we used RT-PCR resulting in the isolation of a cDNA encoding a seven transmembrane receptor termed BLR2. The protein shows significant sequence similarities to the family of G-protein coupled chemokine receptors and turned out to be identical to the recently described receptor EBI1. Northern blot analysis revealed that BLR2 mRNA could be highly stimulated in mitogen- and anti-CD3-treated peripheral blood lymphocytes. BLR2-specific mRNA could be detected in all Epstein-Barr virus positive B cell lines. We show that transcription of the BLR2 gene could be specifically induced in Epstein-Barr virus negative BL 41 cells via estrogen-mediated activation of Epstein-Barr virus nuclear antigen 2, a key regulator of viral and cellular genes in immortalized B cells. Our data suggest an involvement of BLR2 in the regulation of migration in activated lymphocytes and in viral pathogenesis.
Antigens, Viral↗
A versatile flow cytometry-based assay for the determination of short- and long-term natural killer cell activity.
A flow cytometry based method has been developed to assess natural killer (NK) cell activity in both short-term (4 h) and long-term (18 h) NK assays. Target cells were either labeled with PKH-2, c'FDA or D275. Simultaneously, dead cells were identified by counter-staining with the nuclear dye propidium iodide. Using flow cytometry, only D275 in combination with propidium iodide permits the differentiation of four cell populations: live target cells, dead target cells, live effector cells, and dead effector cells. Even after the extended incubation periods (18 h) necessary for the determination of NK activity in some domestic animals these four populations remain clearly distinguishable. Comparison of results with cells of normal human individuals obtained using this D275/propidium iodide flow cytometry assay with data derived from fluorescence microscopy or an endogenous lactate dehydrogenase release assay shows a strong correlation. Since in long-term NK assays a high proportion of dead effector cells is constantly observed this cell population frequently limits the use of the lactate dehydrogenase release assay but does not interfere with the flow cytometry assay presented here. Using this novel assay, we have demonstrated the suppressive effects of defined glycosaminoglycans on long-term porcine NK activity.
Animals↗