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A Sander

Publications and source records attributed to A Sander.

At least 37 records · Page 2Linked to original sources
PubMed2000

Altered heart rate and blood pressure variability in mice lacking the Mas protooncogene.

Heart rate variability is a relevant predictor of cardiovascular risk in humans. A significant genetic influence on heart rate variability is suggested, although the genes involved are ill-defined. The Mas-protooncogene encodes a G-protein-coupled receptor with seven transmembrane domains highly expressed in testis and brain. Since this receptor is supposed to interact with the signaling of angiotensin II, which is an important regulator of cardiovascular homeostasis, heart rate and blood pressure were analyzed in Mas-deficient mice. Using a femoral catheter the blood pressure of mice was measured for a period of 30 min and 250 data values per second were recorded. The mean values and range of heart rate and blood pressure were then calculated. Neither heart rate nor blood pressure were significantly different between knockout mice and controls. However, high resolution recording of these parameters and analysis of the data by non-linear dynamics revealed significant alterations in cardiovascular variability in Mas-deficient animals. In particular, females showed a strong reduction of heart rate variability. Furthermore, the data showed an increased sympathetic tone in knockout animals of both genders. The marked alterations detected in Mas-deficient mice of both genders suggest that the Mas-protooncogene is an important determinant of heart rate and blood pressure variability.

Angiotensin II↗
PubMed1999

Identification and characterization of a novel splice variant of MuSK.

MuSK is a receptor tyrosine kinase that initiates the formation of neuromuscular junctions in response to agrin. Little is known about the ligand-induced activation and kinase-dependent signalling that leads to the clustering of acetylcholine receptors. The ectodomain of these molecule is composed of four Ig-like domains. We describe here the isolation of a novel MuSK splice variant that lacks the third Ig-like domain in its ectodomain. The corresponding RNA is the result of alternative splicing which eliminates two exons. There is 10 times less mRNA for this shorter form than for the long form of MuSK and both forms are regulated coordinately. They decrease strongly after birth and are elevated in denervated muscle. Gene transfer by muscle injection of MuSK DNA into individual muscle fibers demonstrates that kinase-induced acetylcholine receptor clustering caused by overexpression of the two kinases does not depend on the presence of the third Ig-like domain.

Alternative Splicing↗
PubMed1999

[Magnetic resonance imaging of benign and premalignant tumors in childhood].

PURPOSE: To evaluate the potential of MRI in determining benign and premalignant abdominal tumors in childhood. METHODS: MR images of 93 children with 69 malignant and 24 benign abdominal tumors were analyzed retrospectively without and with knowledge of clinical findings. Based on the final diagnosis, MR findings were surveyed with regard to the correct differential diagnosis and to the differentiation between benign and malignant masses. RESULTS: Analysis of MRI alone revealed relatively low sensitivity of 67% for diagnosis of a benign tumor. The main reason was unspecific morphologic criteria leading to the false-negative diagnosis of a malignant tumor. Together with clinical and laboratory findings, sensitivity could be increased to 92%. The main criterion for differentiation of malignant tumors turned to be out the origin of tumor. Benign tumors could be best differentiated by their internal structure. CONCLUSION: When considering clinical findings in pediatric abdominal tumors, MRI represents a valuable modality for differential diagnosis.

Abdominal Neoplasms↗
PubMed1999

Botulism with respiratory insufficiency requiring extra corporeal carbon dioxide removal.

Despite a low incidence of botulism in the industrialized world some cases occasionally occur in Germany after eating contaminated food. Because botulism is rarely seen, most physicians are unfamiliar with its early recognition and treatment. However, immediate intensive care treatment is important. We report the case of a previously healthy 54-year-old female who developed signs of botulism after eating vacuum packed smoked fish and developed severe respiratory insufficiency with difficult carbon dioxide elimination in the days following.

Botulism↗
PubMed1999

Semiquantitative species-specific detection of Bartonella henselae and Bartonella quintana by PCR-enzyme immunoassay.

Bartonella henselae is the main causative agent of cat-scratch disease, and both B. henselae and Bartonella quintana cause angioproliferative disorders such as bacillary angiomatosis. To increase the sensitivity of Bartonella detection by PCR and to improve the species differentiation, we developed a semiquantitative, species-specific PCR-based enzyme immunoassay (EIA). The 16S rRNA gene was selected as the target sequence. Internal nucleotide sequences derived from the amplified 16S rRNA region were used to develop species-specific oligonucleotide probes for B. henselae and B. quintana. Biotin-labeled PCR products were immobilized on streptavidin-coated microtiter plates, hybridized to a digoxigenin-labeled probe, and detected with antidigoxigenin peroxidase conjugate. No cross-hybridization with other Bartonella or non-Bartonella species was observed. This EIA was as sensitive as dot blot hybridization and was 10 times more sensitive than visualization of PCR products on agarose gels. Serial dilutions of B. henselae and B. quintana suspensions demonstrated that an optical density (OD) of approximately 0.200 was equivalent to 5 CFU in the reaction mixture. By comparing the OD of the bacterial dilutions with that obtained from clinical specimens we could determine that the number of CFU in clinical samples ranged from 10(3) to 10(6) CFU/ml. The PCR-EIA developed in the present study is a rapid, sensitive, and simple method for the diagnosis of B. henselae and B. quintana infections.

Bartonella henselae↗
PubMed1999

Molecular analysis of riboflavin synthesis genes in Bartonella henselae and use of the ribC gene for differentiation of Bartonella species by PCR.

The biosynthesis pathway for riboflavin (vitamin B(2)), the precursor of the essential cofactors flavin mononucleotide and flavin adenine dinucleotide, is present in bacteria and plants but is absent in vertebrates. Due to their conservation in bacterial species and their absence in humans, the riboflavin synthesis genes should be well suited either for detection of bacterial DNA in human specimens or for the differentiation of pathogenic bacteria by molecular techniques. A DNA fragment carrying the genes ribD, ribC, and ribE, which encode homologues of riboflavin deaminase (RibD) and subunits of riboflavin synthetase (RibC and RibE), respectively, was isolated from a plasmid-based DNA library of the human pathogen Bartonella henselae by complementation of a ribC mutation in Escherichia coli. Sequence analysis of the ribC gene region in strains of B. henselae, which were previously shown to be genetically different, revealed that the ribC gene is highly conserved at the species level. PCR amplification with primers derived from the ribC locus of B. henselae was used to isolate the corresponding DNA regions in B. bacilliformis, B. clarridgeiae, and B. quintana. Sequence analysis indicated that the riboflavin synthesis genes are conserved and show the same operon-like genetic organization in all four Bartonella species. Primer oligonucleotides designed on the basis of localized differences within the ribC DNA region were successfully used to develop species-specific PCR assays for the differentiation of B. henselae, B. clarridgeiae, B. quintana, and B. bacilliformis. The results obtained indicate that the riboflavin synthesis genes are excellent targets for PCR-directed differentiation of these emerging pathogens. The PCR assays developed should increase our diagnostic potential to differentiate Bartonella species, especially B. henselae and the newly recognized species B. clarridgeiae.

Amino Acid Sequence↗
PubMed1999

Detection of Bartonella henselae DNA by two different PCR assays and determination of the genotypes of strains involved in histologically defined cat scratch disease.

Cat scratch disease (CSD) is a common cause of subacute regional lymphadenopathy, not only in children but also in adults. Serological and molecular studies demonstrated that Bartonella henselae is the etiologic agent in most cases of CSD. Amplification of B. henselae DNA in affected tissue and detection of antibodies to B. henselae are the two mainstays in the laboratory diagnosis of CSD. We designed a retrospective study and investigated formalin-fixed, paraffin-embedded lymph nodes from 60 patients (25 female, 35 male) with histologically suspected CSD by PCR amplification. The sensitivities of two different PCR assays were compared. The first primer pair amplified a 296-bp fragment of the 16S rRNA gene in 36 of the 60 samples, corresponding to a sensitivity of 60%. The second primer pair amplified a 414-bp fragment of the htrA gene in 26 of the 60 lymph nodes, corresponding to a sensitivity of 43.3%. Bartonella DNA could be detected in a total of 39 (65%) of the 60 lymph nodes investigated. However, histopathologic findings are typical but not specific for CSD and cannot be considered as a "gold standard" for diagnosis of CSD. The sensitivity of the PCR assays increased from 65 to 87% if two criteria (histology and serology) were used in combination for diagnosis of CSD. Two genotypes (I and II) of B. henselae are described as being involved in CSD. Genotype I was found in 23 (59%) and genotype II was found in 9 (23%) of the 39 PCR-positive lymph nodes. Seven (18%) lymph nodes were negative in both type-specific PCR assays. Thirty (50%) of our 60 patients were younger than 20 years old (15 were younger than 10 years), 20 (33%) were between 21 and 40 years old, and 10 (17%) patients were between 41 and 84 years old. Our data suggest that detection of Bartonella DNA in patients' samples might confirm the histologically suspected diagnosis of CSD.

Adolescent↗
PubMed1998

Percutaneous dilatational tracheostomy--early results and long-term outcome of 326 critically ill patients.

OBJECTIVE: To analyze perioperative and postoperative complications and long-term sequelae following percutaneous dilatational tracheostomy (PDT). DESIGN: A prospective clinical study of patients undergoing PDT. SETTING: Seven intensive care units at a University hospital PATIENTS: 326 intensive care patients (202 male, 124 female; age: 11-95 years) with indications for tracheostomy. INTERVENTIONS: Using tracheoscopic guidance, 337 PDTs were performed according to Ciaglias' method. In 106 decannulated patients, tracheal narrowing was assessed by plain tracheal radiography. RESULTS: Two procedure-related deaths were seen (0.6%). Perioperative and postoperative complications occurred with 9.5% of the PDTs. One of 106 patients, who were followed-up for at least 6 months, showed a clinically relevant tracheal stenosis. Subclinical tracheal stenosis of at least 10% of the cross-sectioned area was recognized in 46 of 106 patients (43.4%). In the univariate analysis, the degree of stenosis was influenced by the age of the patient (p = 0.044), the duration of intubation prior to PDT (p = 0.042) and by the duration of cannulation (p = 0.006). These parameters had no statistical significance in a multiple regression model. CONCLUSION: When performed by experienced physicians, percutaneous dilatational tracheostomy under fiberoptic guidance is a safe method. The risks of early complications and of clinically relevant tracheal stenoses are low. Subclinical tracheal stenoses are found in about 40% of patients following PDT.

Adolescent↗
PubMed1998

Two different genotypes of Bartonella henselae in children with cat-scratch disease and their pet cats.

Two genotypes (I and II) of Bartonella henselae are involved in cat-scratch disease (CSD). Lymph node biopsies were taken from 3 children suffering from CSD, and blood cultures were obtained from their pet cats. Cat-scratch disease was confirmed serologically, histologically and by detection of B. henselae DNA in all 3 lymph nodes by PCR. Bartonella henselae grew in all cats' blood cultures. The first 2 children were siblings. Both children and their pet cats were infected with B. henselae genotype II, and the third patient and her cat were infected with B. henselae genotype I. In all cases, there were no essential differences in the clinical manifestations of the infection caused by these 2 genotypes of B. henselae.

Adolescent↗
PubMed1998

Multiparametric analysis of heart rate variability used for risk stratification among survivors of acute myocardial infarction.

A multiparametric heart rate variability analysis was performed to prove if combined heart rate variability (HRV) measures of different domains improve the result of risk stratification in patients after myocardial infarction. In this study, standard time domain, frequency domain and non-linear dynamics measures of HRV assessment were applied to 572 survivors of acute myocardial infarction. Three parameter sets each consisting of 4 parameters were applied and compared with the standard measurement of global heart rate variability HRVi. Discriminant analysis technique and t-test were performed to separate the high risk groups from the survivors. The predictive value of this approach was evaluated with receiver operator (ROC) and positive predictive accuracy (PPA) curves. Results--The discriminant analysis shows a separation of patients suffered by all cause mortality in 80% (best single parameter 74%) and sudden arrhythmic death in 86% (73%). All parameters of set 1 show a high significant difference (p < 0.001) between survivors and non-survivors based on two-tailed t-test. The specificity level of the multivariate parameter sets is at the 70% sensitivity level (ROC) about 85-90%, whereas HRVi shows maximum levels of 70%. The PPA in the all cause mortality group is at the 70% sensitivity level twice as high as the univariate HRV measure and increases to more than fourfold as high within the VT/VF group. In conclusion, in this population, the multiparametric approach with the combination of four parameters from all domains especially from NLD seems to be a better predictor of high arrhythmia risk than the standard measurement of global heart rate variability.

Arrhythmias, Cardiac↗
PubMed1998

Seroprevalence of antibodies to Bartonella henselae in patients with cat scratch disease and in healthy controls: evaluation and comparison of two commercial serological tests.

Serologic testing for the presence of antibodies to Bartonella henselae is a widely accepted diagnostic procedure for laboratory confirmation of the diagnosis of cat scratch disease (CSD). In this study a commercially available indirect immunofluorescence assay (IFA) based on B. henselae-infected human larynx carcinoma cells (test A) was evaluated. Sera from 42 patients with CSD (20 confirmed by PCR) and 270 sera from healthy controls (consisting of 63 cat owners, 65 individuals whose last close contact with cats was >6 months previously, and 142 persons who had never been exposed to cats) were investigated for antibodies to B. henselae. All patients with CSD had titers of immunoglobulin G (IgG) to B. henselae of 128 or higher (test A; sensitivity, 100%). Of the 270 controls 189 (70%) were seronegative (titer, <64), 38 (14.1%) had titers of 64, 30 (11.1%) had titers of 128, 9 (3.3%) had titers of 256, and 4 (1.5%) had high titers, 512 (test A; specificity, 70%). Of the cat owners and individuals who had never had close contact with cats, 71.4 and 71.12%, respectively, were seronegative, and titers of 64, 128, 256, and 512 were found in 14.3 and 16.2%, 1.6 and 10.5%, 9.5 and 0.7%, and 3.2 and 1.4%, respectively. The sera from the patients and from the first 100 healthy adults without a history of close contact with cats were additionally tested with a second commercially available IFA, based on Vero cells infected with B. henselae and Bartonella quintana (test B). The sensitivity and specificity of test B were 93 and 73%, respectively. For patients with CSD the cross-reactivity between B. henselae and B. quintana in this test was 95%. Both systems are highly sensitive but less specific for detection of IgG antibodies to B. henselae in samples from patients with clinically apparent CSD. For detection of IgM antibodies, test A seems to be more sensitive (88%) and more specific (95%) than test B (sensitivity and specificity of 64 and 86%, respectively). The data show that the seroprevalence of antibodies to B. henselae in German individuals is high (30%). Low antibody levels are not sufficient evidence of active or prior infection.

Adolescent↗
PubMed1998

Comparison of different DNA fingerprinting techniques for molecular typing of Bartonella henselae isolates.

Seventeen isolates of Bartonella henselae from the region of Freiburg, Germany, obtained from blood cultures of domestic cats, were examined for their genetic heterogeneity. On the basis of different DNA fingerprinting methods, including pulsed-field gel electrophoresis (PFGE), enterobacterial repetitive intergenic consensus (ERIC)-PCR, repetitive extragenic palindromic (REP) PCR, and arbitrarily primed (AP)-PCR, three different variants were identified among the isolates (variants I to III). Variant I included 6 strains, variant II included 10 strains, and variant III included only one strain. By all methods used, the isolates could be clearly distinguished from the type strain, Houston-1, which was designated variant IV. A previously published type-specific amplification of 16S rDNA differentiated two types of the B. henselae isolates (16S rRNA types 1 and 2). The majority of the isolates (16 of 17), including all variants I and II, were 16S rRNA type 2. Only one isolate (variant III) and the Houston-1 strain (variant IV) comprised the 16S rRNA type 1. Comparison of the 16S rDNA sequences from one representative strain from each of the three variants (I to III) confirmed the results obtained by 16S rRNA type-specific PCR. The sequences from variant I and variant II were identical, whereas the sequence of variant III differed in three positions. All methods applied in this study allowed subtyping of the isolates. PFGE and ERIC-PCR provided the highest discriminatory potential for subtyping B. henselae strains, whereas AP-PCR with the M13 primer showed a very clear differentiation between the four variants. Our results suggest that the genetic heterogeneity of B. henselae strains is high. The methods applied were found useful for typing B. henselae isolates, providing tools for epidemiological and clinical follow-up studies.

AIDS-Related Opportunistic Infections↗
PubMed1997

Hemofiltration increases IL-6 clearance in early systemic inflammatory response syndrome but does not alter IL-6 and TNF alpha plasma concentrations.

OBJECTIVE: To test the hypothesis that continuous hemofiltration increases interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF alpha) clearances and results in decreased cytokine plasma concentrations independent of renal function in patients with early SIRS. DESIGN: Prospective, controlled, randomized study. SETTING: Intensive care units at a university hospital. PATIENTS: 28 consecutive patients who fulfilled the criteria of the systemic inflammatory response syndrome (SIRS). INTERVENTIONS: Patients with SIRS were randomly assigned to either a hemofiltration or a control group irrespective of renal function. In patients of the hemofiltration group an isovolemic hemofiltration was initiated directly after the diagnosis of SIRS and maintained for at least 48 h. MEASUREMENTS AND RESULTS: A significant (p < 0.001) increase in total IL-6 clearance (hemofiltrate + urine), but not in TNF alpha clearance, was observed with hemofiltration. However, the plasma concentrations of both cytokines remained unchanged. Hemodynamic variables did not change significantly. CONCLUSIONS: Continuous hemofiltration increases IL-6 plasma clearance but not TNF alpha clearance. However, hemofiltration failed to decrease plasma concentrations of TNF alpha and IL-6 and, therefore, cannot be used effectively for cytokine elimination in SIRS. Accordingly, beneficial effects occasionally reported with hemofiltration are unlikely to be expected due to elimination of IL-6 or TNF alpha.

Adult↗
PubMed1997

[Animal experiment studies of arterialization of the portal vein in liver transplantation using the Göttingen minipig].

The aim of the present experimental investigation was to assess the circulatory, biochemical and histopathological consequences of complete portal vein arterialization of the transplanted liver in 'Göttinger' miniature pigs. Orthotopic liver transplantations using a passive portojugular shunt were performed in six male 'Göttinger' miniature pigs. Using an iliac artery segment interposition of the animal donor, the hepatic artery (HA) of the transplant liver was anastomized end-to-end and the portal vein (PA) also united with the internal iliac artery stump end-to-end. The central anastomosis was performed onto the suprarenal aorta. Portal vein blood was drained into the infrahepatic caval vein via an end-to-side shunt (PCS). During the course, the following parameters were determined: arterial blood pressure, venous pressure, cardiac output, electromagnetic blood flow measurements across the HA, PA, and PCS, PA mean pressure, transaminases, partial thromboplastin time and fibrinogen. Liver biopsies and autopsy specimens were investigated. One of six animals died a few hours postoperatively, two of six died after 48 and 72 h, respectively, whereas three pigs survived the scheduled 7 days. The cardiac output fell intraoperatively initially by an average of 20% but had approximately the starting volume of 2.2 l/min at the end of the operation. Although the diameter of the anastomosis was reduced to 4 mm, the flow in the arterialized PA on average was 340 ml/min when the vessel clamp was opened. At the end of operation the mean was 380 ml/min, the interval of measurement being 75 min. The flow across the PCS and the HA were constant during the course. As mechanism for this phenomenon, autoregulation of the liver blood flow on a sinusidal level has been suggested. The biochemical results and the histopathological findings showed no change compared to previous findings in a control group of animals in which liver transplantation was performed by our team. Complete arterialization of the PA is well tolerated in liver transplantation in 'Göttinger' miniature pigs with regard to circulation and liver function in a short-term trial of a maximum of 7 days. Long-term results are still to come.

Anastomosis, Surgical↗