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S Fischer

Publications and source records attributed to S Fischer.

At least 163 records · Page 9Linked to original sources
PubMed1998

Reconstituted recombinant factor VIII can be safely infused continuously for at least three days: it is a poor microbial growth medium.

Reconstituted recombinant factor VIII (FVIIIrec) loses little biologic activity at room temperature for up to seven days and continuous infusion is convenient, effective hemostatically and requires less FVIIIrec concentrate than treatment by conventional bolus injections. However, the potential for bacterial contamination, with proliferation to high levels that can cause bacteremia, is a concern with continuous infusion. We studied the growth properties at 4, 25 and 35 degrees C in reconstituted FVIIIrec (Kogenate) and at 25 degrees C in 5% dextrose in water (D5%W) of three isolates each of Staphylococcus epidermidis, Staphylococcus aureus, Enterobacter cloacae, Klebsiella oxytoca, Serratia marcescens, Acinetobacter calcoaceticus, Stenotrophomonas maltophilia, Pseudomonas aeruginosa, Burkholderia cepacia, Flavobacterium spp. and Candida albicans, species most likely to contaminate infusate during preparation or administration and which have been implicated in more than 95% of all outbreaks and sporadic cases of nosocomial bloodstream infection traced to contaminated admixtures, biologic agents or medications administered parenterally. Reconstituted FVIIIrec allowed growth of only three species at 25 degrees C and 35 degrees C: S. marcescens, S. maltophilia and P. aeruginosa; logarithmic growth appeared only after 24-48 h. D5%W allowed growth of two gram-negative species, S. marcescens and B. cepacia. We conclude that reconstituted FVIIIrec (Kogenate) is a poor growth medium for most nosocomial pathogens, comparable with D5%W. If reconstituted aseptically, continuous infusion of reconstituted FVIIIrec should be safe, and it should not be necessary to replace the container or tubing more frequently than every 3 days, an administration schedule that can provide effective hemostasis at lower cost.

Bacteremia↗
PubMed1998

GAIA: framework annotation of genomic sequence.

As increasing amounts of genomic sequence from many organisms become available, and as DNA sequences become a primary reagent in biologic investigations, the role of annotation as a prospective guide for laboratory experiments will expand rapidly. Here we describe a process of high-throughput, reliable annotation, called framework annotation, which is designed to provide a foundation for initial biologic characterization of previously unexamined sequence. To examine this concept in practice, we have constructed Genome Annotation and Information Analysis (GAIA), a prototype software architecture that implements several elements important for framework annotation. The center of GAIA consists of an annotation database and the associated data management subsystem that forms the software bus along which other components communicate. The schema for this database defines three principal concepts: (1) Entries, consisting of sequence and associated historical data; (2) Features, comprising information of biologic interest; and (3) Experiments, describing the evidence that supports Features. The database permits tracking of annotation results over time, as well as assessment of the reliability of particular results. New framework annotation is produced by CARTA, a set of autonomous sensors that perform automatic analyses and assert results into the annotation database. These results are available via a Web-based query interface that uses graphical Java applets as well as text-based HTML pages to display data at different levels of resolution and permit interactive exploration of annotation. We present results for initial application of framework annotation to a set of test sequences, demonstrating its effectiveness in providing a starting point for biologic investigation, and discuss ways in which the current prototype can be improved. The prototype is available for public use and comment at http://www.cbil.upenn.edu/gaia.

Amino Acid Sequence↗
PubMed1998

Characterization of a bovine viral diarrhea virus isolated from roe deer in Germany.

The 5' untranslated region (5' UTR) of cytopathogenic pestiviruses isolated from two seronegative roe deer (Capreolus capreolus) in northern Germany was partially sequenced and compared with those of 28 other pestiviruses. Due to the occurrence within a narrow location and the complete identity of the sequenced fragments from both roe deer isolates (SH9 and SH11) they seem to belong to the same bovine virus diarrhea virus (BVDV) strain called SH9/11. This strain is highly homologous (up to 93% identity) to "classical" BVDV strains. However, SH9/11 has characteristic variations in its 5' UTR distinct from all other pestiviruses analyzed in this study. Strain SH9/11 is more similar to BVDV group I than to group II, although it is clearly separated from all other cattle isolates tested. In monoclonal antibody (mAb)-typing studies, isolate SH9 reacted with one pestivirus-specific mAb (C16), with two BVDV specific mAbs (N2B12 and D5), and with one mAb (f48) raised against the E2 protein of classical swine fever virus out of a panel of 13 mAbs. The separate position of strain SH9/11 again was demonstrated by the unique reaction pattern of isolate SH9 when compared with other mAb f48-positive BVDV and BDV strains. All these results indicate that indicate that distinct BVDV strains might exist among freeranging roe deer in Germany.

Animals↗
PubMed1998

The regularity of laser keratectomy depth in nonmechanical trephination for penetrating keratoplasty.

BACKGROUND AND OBJECTIVES: To study the regularity of laser keratectomy depth in nonmechanical trephination for penetrating keratoplasty (PK) and to assess its implications on astigmatism and visual acuity (VA). PATIENTS AND METHODS: In this retrospective clinicopathologic study, the authors enrolled 26 women and 32 men (mean age 54 +/- 20 years) with either keratoconus (n = 27) or Fuchs' dystrophy (n = 31), who underwent excimer laser (193 nm) trephination using a manually guided beam. Donor cornea trephination was performed using an artificial anterior chamber and either an automated rotation device (n = 27) or a manually guided beam (n = 31). The minimum residual corneal thickness (MRCT) and the random residual corneal thickness (RRCT), requiring division with scissors in excised patient buttons or corneoscleral donor rims, were assessed in a masked fashion using histologic sections. The postkeratoplasty keratometric net astigmatism, the subjective cylinder, and the VA were evaluated before and after suture removal. RESULTS: In patients with keratoconus, the mean MRCT (13% +/- 14%) and RRCT (38% +/- 20%) were significantly higher than in the patients with Fuchs' dystrophy (7% +/- 11% and 26% +/- 15%, respectively) (P < .01). When an automated rotation device for trephination of the donor cornea was used, the mean MRCT (2% +/- 4%) and RRCT (14% +/- 11%) were significantly smaller than when a manually guided laser beam was employed (15% +/- 12% and 38% +/- 15%, respectively) (P < .001). After suture removal, the VA increased significantly with automated trephination (P = .04), but not with manually guided trephination of the donor cornea (P = .24). However, after a mean follow-up of 30 +/- 8 months, the differences in the mean keratometric astigmatism, refractive cylinder, and VA after automated trephination (3.0 D, 2.6 D, 20/29, respectively) compared with those after manually guided trephination of the donor cornea (4.3 D, 3.9 D, 20/33, respectively) did not reach statistical significance. CONCLUSIONS: The regularity of donor trephination depth can be significantly improved by using an automated rotation device instead of a manually guided beam. Although residual postkeratoplasty astigmatism was not directly related to trephination depth, the improvement of the functional results after suture removal seems to be promoted by automated trephination.

Astigmatism↗
PubMed1998

Characterization of bovine Sarcocystis species by analysis of their 18S ribosomal DNA sequences.

Two Sarcocystis hirsuta isolates from 2 cattle (Bos taurus), 2 Sarcocystis hominis-like isolates from 2 cattle, 1 each Sarcocystis hominis-like isolate from a zoo-born dwarf zebu (B. taurus) and from a zoo-born bison (Bison bison), and 1 each Sarcocystis cruzi isolate from the dwarf zebu and the bison have been characterized by comparing the directly sequenced polymerase chain reaction products of their 18S rRNA genes. Sequences of 2 different isolates from the same species always showed a very high, nearly complete identity to each other both within all or only the conserved overlapping nucleotides. Thus, the 18S rDNA sequences of both S. hirsuta isolates proved to belong to a single species. The same is true for all 3 S. cruzi sequences. The 4 S. hominis-like isolates could not be placed within a single species using these criteria. They formed 2 separate groups (1 cattle isolate and the bison isolate, and the other cattle isolate and the dwarf zebu isolate). The results suggest that zoo-born large mammals do serve as intermediate hosts for Sarcocystis species known from indigenous herbivores, and that there might be another species found in cattle that is morphologically very similar to S. hominis.

Animals↗
PubMed1998

Arg777 plays a major role in the conformation of the colony-stimulating factor-1 receptor intracellular kinase domain.

A point mutation substituting Arg777 by Gln was obtained in a highly conserved region of the human colony-stimulating factor-1 receptor (CSF-1R) sequence. Constitutive expression of wild-type receptors in CHO cells confers susceptibility to CSF-1 for proliferation whereas the mutated receptors exhibited a 90% reduced efficiency in proliferation. We sought to determine the alterations intervening in the CSF-1 signal transduction of the Arg777Gln mutated receptor. We found that ligand binding and ligand-induced CSF-1R internalization were unaffected. CSF-1-induced receptor dimerization and autophosphorylation were impaired to the same extent as mitogen-activated protein kinase activation (90%). However, only phosphatidylinositol 3-kinase activation and ligand-induced receptor ubiquitination were abrogated by the mutation. These features probably reflect the inability of the mutated CSF-1R kinase domain to fold properly and hence to autophosphorylate and/or to associate correctly with transduction proteins. These data may indicate a role for the conserved regions of the RTK kinase domains in the stabilization of the intracellular domain conformation.

Amino Acid Substitution↗
PubMed1998

Bone scintigraphy in non-neoplastic diseases in children.

Since the introduction of 99mTc labeled polyphosphates bone scintigraphy has become a widely accepted method for the evaluation of non-neoplastic bone diseases in children. High quality images require the child's immobilisation and a correct positioning as well as an optimized technical equipment. Two or three phase scintigraphy is the routinely procedure but additional techniques like pinhole images or SPECT can be very helpful for special indications and localisations. Due to the age and sex dependent differences of bone metabolism in the developing skeleton the interpretation of the bone scan in children is more difficult than in adults and requires more experience. Infections, trauma and aseptic necrosis are the most important non-neoplastic diseases requiring bone scintigraphy. Bone scan has a high sensitivity in the early detection of pathological bone metabolism indicating bone disease; other investigations, which are describing morphological changes like X-ray are less sensitive especially at the beginning of the disease. Negative bone scan rools out significant bone disorders with a high certainty. Follow-up studies can give additional informations about the response to therapeutical regimes and about the prognosis. To improve the specificity of a bone scan a combined interpretation of scintigraphy and X-ray is recommended.

Bone Diseases↗
PubMed1998

The GAIA software framework for genome annotation.

We describe a software framework, GAIA, that supports semi-automated annotation of uncharacterized sequence data. The annotation framework incorporates annotation by data source integration, data analysis, and manual data entry. Components of the system include a configurable, open data analysis pipeline, a relational information storage manager, and Java-based graphical user interfaces. We discuss design decisions and tradeoffs in building such a system, and policies and strategies for producing consistent, uniform, high quality annotation.

Base Sequence↗
PubMed1998

Bone mineral density by single photon X-ray absorptiometry in Chilean children and adolescents.

OBJECTIVE: To assess bone mineralization in healthy Chilean children and adolescents, considering sex, age, height, and puberty. METHODS: In a descriptive cross sectional study, the appendicular bone mineral density (BMD) was measured by single photon x-ray absorptiometry at distal (D-BMD) and ultradistal (UD-BMD) regions of the forearm, in 571 healthy children and adolescents of Valparaíso and Viña del Mar, Chile, considering their age, sex, height, calcium intake, and pubertal development according to Tanner. RESULTS: Physical activity was regular; daily average calcium intake was 580 +/- 100 mg and the D-BMD and UD-BMD showed a 3 step growth pattern: Slow increments between 4 and 8 years of age in girls (r = 0.07 and r = 0.37, respectively) and between 4 and 12 years in boys (r = 0.17 and r = 0.39); sharp increases between 8 and 19 years in female adolescents (r = 0.78 and r = 0.73) and between 12 and 20 years in male adolescents (r = 0.82 and r = 0.67); and deceleration of growth from 19 years in female adolescents and 20 years in males. Considering Tanner classifications (T), boys had significant differences in mean D-BMD between T3 and T4 (p < 0.001) and between T4 and T5 (p < 0.001) and in mean UD-BMD between T3 and T4 (p < 0.001). They achieve higher values than women in adulthood. Girls showed significant differences in mean D-BMD between T3 and T4 (p = 0.003) and T4 and T5 (p < 0.001), and in mean UD-BMD between T3 and T4 (p = 0.016). Considering menarche, there was an important increment in bone mass up to 3 years after menarche, and it was significant until 2 years after for D-BMD (p < 0.02) and 1 year after for UD-BMD (p < 0.001). In girls and boys, bone mass increments did not correlate with height increments. A delay in bone mass increments was observed at early Tanner stages. CONCLUSION: Between 4 and 8 years in girls and 4 and 12 years in boys, there is a slow increment in bone density correlated with age and sex. A steeper slope in bone growth started with puberty, correlated with Tanner stage. Bone mineral increments did not correlate with height increments. At the end of pubertal development bone acquisition slowed down. Men achieved higher bone density values than women.

Absorptiometry, Photon↗
PubMed1998

Linear repair versus ventricular reconstruction for treatment of left ventricular aneurysm: a 10-year experience.

OBJECTIVE: To describe a 10-year experience with surgical treatment of left ventricular aneurysm and compare the results of linear repair and ventricular reconstruction. DESIGN: A retrospective data analysis. SETTING: Department of cardiothoracic surgery. PATIENTS: All patients treated with concurrent coronary artery bypass revascularization and surgical repair of ventricular aneurysm from 1985 to 1995. METHODS: Patients underwent either linear repair after aneurysmectomy (group A; n=51) or reconstruction of the left ventricle using a patch (group B, n=10). Preoperative patient characteristics and postoperative mortality and symptomatic results in the two groups were compared with chi(2) and paired "t"-tests. RESULTS: The early mortality rates were 9.8% overall, 7.8%, in group A, and 20% in group B. During a mean follow-up of 58 months, the late mortality rates were 34.5%, 38.2%, and 12.5%. In comparison to patients in group A, those in group B had higher preoperative rates of seriously impaired left ventricular ejection fraction (p=0.01) and pathologic left ventricular end-diastolic pressure (p=0.03) and a prolonged operative aortic cross-clamp time (p=0.04). Early mortality in group B may have been influenced by the initially impaired hemodynamic function and the cross-clamp time. In the longterm, patients in group B had more symptomatic improvement than those in group A (p=0.02). CONCLUSIONS: Ventricular function in patients with left ventricular aneurysm improved after ventricular reconstruction using a patch. Further experience with this procedure should improve postoperative survival and long-term prognosis.

Cardiac Surgical Procedures↗
PubMed1997

The multiple endocrine neoplasia type 2B point mutation switches the specificity of the Ret tyrosine kinase towards cellular substrates that are susceptible to interact with Crk and Nck.

The RET proto-oncogene encodes a Tyrosine Kinase Receptor (RTK) which plays an important function in the proliferation and/or differentiation of neuroectodermic cells. Germline mutation of a methionine to a threonine within the RET TK domain predisposes to the Multiple Endocrine Neoplasia type 2B (MEN 2B). It has been demonstrated that, unlike c-Ret, the MEN 2B mutated Ret displays constitutive TK activity, tyrosine autophosphorylation and transforms fibroblasts. However, this oncoprotein is more than a fully activated wild-type (WT) Ret TK since it also displays modified substrate specificity. Change in substrate specificity leads to the tyrosine autophosphorylation of MEN 2B Ret on new sites as well as the phosphorylation of several novel downstream targets. But, none of these substrates have been identified and the ability of MEN 2B Ret phosphoprotein to interact with Src Homology 2 (SH2) domain containing molecules has been poorly investigated. In this report, using a constitutively activated Ret TK form, Ret-ptc 2, we demonstrate that the MEN 2B as the activated WT Ret TK binds to several SH2 signalling proteins such as Shc, Grb-2, Phospholipase Cgamma, Crk and Nck. However, in contrast to the activated WT form, expression of the MEN 2B mutated Ret-ptc 2 results in the tyrosine phosphorylation of a panel of proteins which interestingly interact with Crk and Nck. We identified Paxillin, a cytoskeletal protein as one of the Crk associated proteins that is dramatically phosphorylated in MEN 2B but not in WT Ret expressing cells. These data suggest that MEN 2B mutated Ret triggers distinct signalling pathways that might be related to its transforming power.

Adaptor Proteins, Signal Transducing↗
PubMed1997

Structural mapping of the active site specificity determinants of human tissue-type plasminogen activator. Implications for the design of low molecular weight substrates and inhibitors.

The recent structure determination of the catalytic domain of tissue-type plasminogen activator (tPA) suggested residue Arg174 could play a role in P3/P4 substrate specificity. Six synthetic chromogenic tPA substrates of the type R-Xaa-Gly-Arg-p-nitroanilide, in which R is an N-terminal protection group, were synthesized to test this property. Although changing the residue Xaa (in its L or D form) at position P3 from the hydrophobic Phe to an acidic residue, Asp or Glu, gave no improvement in catalytic efficiency, comparative analysis of the substrates indicated a preference for an acidic substituent occupying the S3 site when the S4 site contains a hydrophobic or basic moiety. The 2.9 A structure determination of the catalytic domain of human tPA in complex with the bis-benzamidine inhibitor 2, 7-bis-(4-amidinobenzylidene)-cycloheptan-1-one reveals a three-site interaction, salt bridge formation of the proximal amidino group of the inhibitor with Asp189 in the primary specificity pocket, extensive hydrophobic surface burial, and a weak electrostatic interaction between the distal amidino group of the inhibitor and two carbonyl oxygens of the protein. The latter position was previously occupied by the guanidino group of Arg174, which swings out to form the western edge of the S3 pocket. These data suggest that the side chain of Arg174 is flexible, and does not play a major role in the S4 specificity of tPA. On the other hand, this residue would modulate S3 specificity, and may be exploited to fine tune the specificity and selectivity of tPA substrates and inhibitors.

Arginine↗
PubMed1997

Lysine 156 promotes the anomalous proenzyme activity of tPA: X-ray crystal structure of single-chain human tPA.

Tissue type plasminogen activator (tPA) is the physiological initiator of fibrinolysis, activating plasminogen via highly specific proteolysis; plasmin then degrades fibrin with relatively broad specificity. Unlike other chymotrypsin family serine proteinases, tPA is proteolytically active in a single-chain form. This form is also preferred for therapeutic administration of tPA in cases of acute myocardial infarction. The proteolytic cleavage which activates most other chymotrypsin family serine proteinases increases the catalytic efficiency of tPA only 5- to 10-fold. The X-ray crystal structure of the catalytic domain of recombinant human single-chain tPA shows that Lys156 forms a salt bridge with Asp194, promoting an active conformation in the single-chain form. Comparisons with the structures of other serine proteinases that also possess Lys156, such as trypsin, factor Xa and human urokinase plasminogen activator (uPA), identify a set of secondary interactions which are required for Lys156 to fulfil this activating role. These findings help explain the anomalous single-chain activity of tPA and may suggest strategies for design of new therapeutic plasminogen activators.

Amino Acid Chloromethyl Ketones↗
PubMed1997

Two-dimensional electrophoretic analysis of vesicular and micellar proteins of gallbladder bile.

Proteins associated with lipid vesicles or mixed micelles of human gallbladder bile were separated by Sepharose-2B gel filtration chromatography followed by protein concentration and delipidation. After two-dimensional polyacrylamide gel electrophoresis and silver staining up to 59 and 471 polypeptide spots were counted in vesicular and micellar fractions, respectively. As major components the plasma proteins transferrin, albumin, alpha-fibrinogen, beta-fibrinogen, gamma-immunoglobulin G, immunoglobulin light chains, alpha-1 antitrypsin and haptoglobin alpha-2 chain were identified in the lipid vesicles by comparison with human protein reference maps. However, most biliary proteins including the anionic polypeptide fraction are associated with mixed micelles. The pathophysiological significance of these proteins associated with lipids needs to be investigated further.

Bile↗
PubMed1997

CSF-1 stimulation induces the formation of a multiprotein complex including CSF-1 receptor, c-Cbl, PI 3-kinase, Crk-II and Grb2.

Recently c-Cbl has been reported to be phosphorylated upon CSF-1 stimulation. The product of the c-cbl proto-oncogene (c-Cbl) is a 120 kDa protein harboring several docking sites for Src homology 2 (SH2) domain containing proteins and proline-rich regions that have been shown to allow its constitutive association with the SH3 domains of Grb2. We demonstrate here that CSF-1 exposure of stable transfectant CHO cells expressing the CSF-1 receptor induced the sustained tyrosine phosphorylation of c-Cbl and its subsequent association with Crk-II and the p85 kDa subunit of the PI 3-kinase, while it constitutively associates with Grb2. We demonstrate by in vitro experiments that these associations require the SH2 domain of Crk-II and both the C- and N-terminal SH2 domains of the p85 subunit of the PI 3-kinase. cCbl is the major PI 3-kinase-containing protein in c-Fms expressing CHO cells upon CSF-1 stimulation. Thus c-Cbl behaves as a core protein, allowing the formation of a quaternary complex including, Crk-II, PI 3-kinase and Grb2. We provide evidence that this multiprotein complex can interact with the tyrosine phosphorylated CSF-1 receptor through the unoccupied SH2 domain of Grb2.

Adaptor Proteins, Signal Transducing↗
PubMed1997

[Quality of life in home ventilation].

BACKGROUND: The purpose of this study is to assess quality of life in patients with chronic respiratory failure who require home mechanical ventilation (HMV). PATIENTS AND METHODS: Patients with COPD (n = 20), scoliosis (n = 20), neuromuscular diseases (n = 20) and others (n = 7) were examined. A specific questionnaire containing forms for the patient, the physician and for the relatives was developed according to the formulation of the question (Fragebogen zur chronischen Heimbeatmung = FCH, Interview zur chronischen Heimbeatmung = ICH). In addition to that the Hospital Anxiety and Depression Scale (HAD) and the Asthma Quality of Life Questionnaire were used. Arterial blood gas tensions, pulmonary function and inspiratory mouth occlusion pressure were studied. RESULTS: Quality of life in patients with scoliosis and neuromuscular diseases is improved during HMV compared to patients with COPD who especially are impaired with regard to psychological and functional conditions. Correlations with physiological parameters and with the compliance could not be observed. CONCLUSION: Despite progression of the disease HMV enhances quality of life in patients with scoliosis and neuromuscular diseases. The outcome in COPD is less evident. Therefore the indication must be considered more critically.

Adult↗