Search PubMed⌕ Search

Biomedical subjects

S Knapp

Publications and source records attributed to S Knapp.

At least 91 records · Page 5Linked to original sources
PubMed1996

Influence of pentoxifylline on cytokine levels and inflammatory parameters in septic shock.

OBJECTIVE: To evaluate the influence of pentoxifylline (PTX), a phosphodiesterase inhibitor, on cytokines and inflammatory proteins in patients suffering from septic shock. DESIGN: Prospective study comparing a therapy group to a matched control group. SETTING: Medical intensive care unit at a university hospital. PATIENTS: Twenty four patients fulfilling the criteria of septic shock were included in this study. Twelve patients received PTX (therapy group) and 12 patients matched for diagnosis, age and gender served as the control group. INTERVENTIONS: Pentoxifylline at 1 mg/kg per hour over 24 h in the therapy group. MEASUREMENTS AND RESULTS: Cytokine levels [tumor necrosis factor-alpha (TNF)], soluble TNF receptor [TNF-R], and interleukin-6 [IL-6] and inflammatory proteins [C-reactive protein, alpha-1-antitrypsin (AAT), fibronectin, and haptoglobin], as well as hemodynamic parameters and the APACHE III score were evaluated before initiation of therapy and 24 h-later. After 24 h, TNF levels were significantly lower in the therapy group (p = 0.013), while IL-6 levels were significantly higher in the therapy group (p = 0.030). Within the 24 h TNF declined significantly in the therapy group (p = 0.006), while IL-6 showed a significant increase (p = 0.043). AAT and the APACHE III score tended to differ significantly after 24 h between the groups [AAT levels higher in the therapy group (p = 0.05), APACHE III score lower (p = 0.05)]. In the therapy group, the systemic vascular resistance index was significantly higher after 24 h (p = 0.0026) whereas the cardiac index declined (p = 0.035). CONCLUSIONS: PTX does influence TNF levels in septic shock patients. Nevertheless, inhibiting a single mediator in severe septic shock cannot stop the inflammatory overreaction.

APACHE↗
PubMed1996

[Mucormycosis--a rare complication in patients with diabetes mellitus].

Mucormycosis usually occurs in immunocompromised patients or in patients with diabetes mellitus. Pathogens are moulds of the mucorales species. The diagnosis is made by histological examination of biopsies. A 39 year-old patient with insulin-dependent diabetes mellitus was admitted with a tentative diagnosis of a tumour of the maxilla. After diagnosis of hyphae of the mucorales species, the patient's diabetes was stabilised and he was treated over 17 weeks with amphotericin B (40 mg per day) and made a good recovery. A 58 year-old insulin-dependent patient with ethmoidali and sphenoidali sinusitis did not respond to antibiotic therapy. Mucormycosis was diagnosed by means of biopsy. Although treatment with amphotericin B was started, the patient died after 3 weeks due to multiple organ failure.

Adult↗
PubMed1995

Preliminary crystallographic analysis of an extremely thermostable glutamate dehydrogenase from the archaeon Pyrococcus woesei.

The extremely heat-stable glutamate dehydrogenase (GluDH) from Pyrococcus woesei was crystallized by the hanging-drop vapour-diffusion method. Crystals suitable for X-ray crystallographic investigations were obtained using polyethylene glycol (PEG) 4000 and ammonium acetate as precipitating agents. The crystals obtained diffract to a resolution of 2.8 A, have a prismatic shape and grow up to 0.5 mm in their maximal dimension. They belong to the triclinic system (space group P1; a = 90.9, b = 92.8, c = 107.1 A, alpha = 69.1, beta = 80.7, Vgamma = 65.0 degrees ) with a unit-cell volume of 765052 A(3) which accommodates one GluDH hexamer of 276 kDa. The averaged density of the crystal determined by Ficoll-gradient centrifugation is 1.15 g cm(-3), which corresponds to a molecular mass of 255 kDa in the unit cell. A native data set has been collected on an MAR image-plate system using Cu Kalpha radiation. The completeness of the data set in the range 316-3 A is 74%, and contains 64% of the data in the outer shell (3.4-2.8 A), with an average R(merge) value of 9%. Calculation of self-rotation functions revealed the 32 symmetry of the hexamer; 3 non-crystallographic twofold axes were found at a distance of 120 degrees in a plane perpendicular to the non-crystallographic threefold axis.

Journal Article↗
PubMed1995

DNA-binding surface of the Sso7d protein from Sulfolobus solfataricus.

We have used nuclear magnetic resonance (n.m.r.) spectroscopy to identify the DNA-binding surface of the abundant, small and basic protein Sso7d from the hyperthermophilic archaebacterium Sulfolobus solfataricus. The Sso7d protein was previously found to bind strongly to double-stranded DNA sequences and to protect DNA from thermal denaturation, indicating that it might assume a similar function in vivo. Several amide resonances in two-dimensional n.m.r. 1H, 15N correlation spectra of 15N-enriched Sso7d are shifted and broadened upon addition of small amounts of ten base-pair or 19 base-pair duplex DNA oligomers under conditions where Sso7d-DNA complexes exchange rapidly on the n.m.r. time scale. The locations of the corresponding amides in the Sso7d structure define the surface that interacts with DNA. This surface coincides with a continuous region of strong positive electrostatic potential, which was calculated by means of numerical solution of the Poisson-Boltzmann equation. A model of the non-specific Sso7d-DNA complex is suggested based on the present data and previously obtained evidence that Sso7d interacts with the DNA major groove. The protein-DNA interface consists of a triple-stranded beta-sheet, which interacts with the DNA major groove and a reverse turn connecting the two strands of a double-stranded beta-sheet, which interacts with the minor groove. We note that the five (of 14) lysine side-chains that are specifically subjected to N zeta-monomethylation in the cell are located on surfaces of Sso7d that are exposed to the solvent in the proposed Sso7d-DNA complex.

Archaeal Proteins↗
PubMed1995

Tris(3,5-dimethylpyrazol-1-yl)methylsilane.

The structure consists of discrete molecules of tris-(3,5-dimethylpyrazol-1-yl)methylsilane, C16H24N6Si, that exhibit distorted tetrahedral SiN(pyrazole)3C geometry about the Si atom. The Si and methyl C atoms lie on threefold axes. The C--Si--N and N--Si--N bond angles are 111.3 (2) and 107.5 (2) degrees, respectively, while the Si--N bond length is 1.745 (5) A. The present work provides the first reported structure containing an Si--N(pyrazole) linkage.

Crystallography↗
PubMed1995

Crystallization and preliminary crystallographic analysis of an amylopullulanase from the hyperthermophilic archaeon Pyrococcus woesei.

The thermostable amylopullulanase from Pyrococcus woesei was crystallized. Crystals, suitable for a crystallographic analysis up to a size of 0.6 mm in their longest dimension, have been obtained by the vapor diffusion method in a solution containing polyethyleneglycol 4000 (PEG 4000), isopropanol, and Tris/Cl- buffer pH 7.5. Crystals grown under these conditions form hexagonal rods and diffract to a maximum resolution of 3 A. The crystals belong to the trigonal lattice type with the spacegroup P3(1)21 or P3(2)21, respectively, have the cell dimensions a = b = 96.8 A, c = 196.2 A, alpha = beta = 90 degrees, gamma = 120 degrees. The crystals have a theoretical packing density of 2.7 A3/Da, assuming one molecule with a molecule weight of 88.8 kDa in the asymmetric unit. Furthermore the self-rotation analysis of the dataset revealed only crystallographic symmetries. The merged native data of two crystals resulted in a 88% complete dataset.

Archaea↗
PubMed1995

Reactivity of five anti-HIV-1 subtype O specimens with six different anti-HIV screening ELISAs and three immunoblots.

Five anti-subtype O specimens were tested by anti-HIV-1/2 screening and confirmatory assays. They can be divided into three specimens, reactive with all ELISAs, independent of the nature of the antigen (recombinant proteins or peptides) and test configuration (indirect ELISA or double antigen/sandwich ELISA). One specimen was not detected by one peptide based ELISA. One specimen was only recognized by two ELISAs and should be considered as a marker sample for the weakness of currently used ELISAs with anti-subtype O. Three different immunoblot assays available commercially detected two of the specimens with a major binding of gp160 and other viral bands, especially the integrase and reverse transcriptase. Another two specimens lacked reactivity with glycoproteins almost completely, but showed some staining with the enzymes of HIV, and would most probably be interpreted as indeterminate. The fifth specimen, which was also missed by most of the ELISAs, had very faint staining of the gp160 and a very weak staining of p24, and would most probably be interpreted as negative. Adaption of currently available tests to anti-subtype O is needed for the future reliability of anti-HIV diagnostic reagents.

AIDS Serodiagnosis↗
PubMed1995

Lethal Waterhouse-Friderichsen syndrome in posttraumatic asplenia.

We herein report a case of fulminant lethal Waterhouse-Friderichsen syndrome in an elderly female patient seven years after posttraumatic splenectomy. In contrast to various reports, this patient had not been vaccinated against Streptococcus pneumoniae, Neisseria meningitidis, or Haemophilus influenzae, respectively, although infections with these microorganisms are known to cause the main lethal diseases in asplenic patients. Again, we recommend obligatory vaccinations against the mentioned bacteria for it is known that this decreases the risk of fatal septic events in these patients. To optimize prevention, it is imperative to vaccinate patients undergoing splenectomy before discharge from hospital.

Blood Coagulation Tests↗
PubMed1995

[Juvenile bone cysts. Relative value and therapy results of cortisone injections].

Seventy-one children and adolescents with unicameral bone cysts were treated between 1982 and 1992. Fifty-one percent were in the proximal humerus, 34% in the femur, 10% in the tibia, and only 5% in other sites. Until 1986 biopsies were routinely done. Since then, only selected cases have been biopsied because of uncertainty in the radiological diagnosis. In 70% the diagnosis was a pathological fracture as a result of the cyst. Cortisone injections were introduced in 1982. It replaced currettage and bone grafting, which was the routine treatment until then. Ninety-two percent of the cysts healed or healed with residuals according to the Neer classification. Additional osteosynthesis was done in pathological fractures of the femoral neck. The results are achieved with little morbidity, and low cost which justifies continuation of this treatment protocol.

Adolescent↗
PubMed1994

The molecular chaperonin TF55 from the Thermophilic archaeon Sulfolobus solfataricus. A biochemical and structural characterization.

The purification and characterization of a new type of thermostable chaperonin from the archaebacterium Sulfolobus solfataricus is described. The chaperonin forms a hetero-oligomeric complex of two different, but closely related, subunits, which we have assigned TF55-alpha and TF55-beta. Their N-terminal sequences and amino acid residue compositions are reported. Two-dimensional projections of the chaperonin have been reconstructed from electron microscopy images, showing a 9-fold symmetrical complex, about 17.5 nm in height and 16 nm in diameter, with a central cavity of 4.5 nm. The complex is resistant to denaturing agents at room temperature and only pH values lower than 2 lead to dissociation. The separated subunits do not reassemble spontaneously but require Mg2+ and ATP for complex formation. Both subunits are necessary for formation of the TF55 oligomer. Significant structural changes have been observed after phosphorylation, thus providing evidence for a structural mobility during the chaperonin-assisted folding process of a protein. The phosphorylation reaction is modulated by potassium and magnesium ions. Magnesium seems to have an inhibitory effect, whereas potassium enhances this reaction.

Amino Acid Sequence↗
PubMed1994

Transgenic tomato lines containing Ds elements at defined genomic positions as tools for targeted transposon tagging.

We have introduced a genetically marked Dissociation transposable element (DsHPT) into tomato (Lycopersicon esculentum) by Agrobacterium tumefaciens-mediated transformation. Probes for the flanking regions of the T-DNA and transposed DsHPT elements were obtained with the inverse polymerase chain reaction (IPCR) technique and used in RFLP linkage analyses. The RFLP map location of 11 T-DNAs carrying DsHPT was determined. The T-DNAs are distributed on 7 of the 12 tomato chromosomes. To explore the feasibility of gene tagging strategies in tomato using DsHPT, we examined the genomic distribution of DsHPT receptor sites relative to the location of two different, but very closely linked, T-DNA insertion sites. After crosses with plants expressing Ac transposase, the hygromycin phosphotransferase (HPT) marker on the Ds element and the excision markers beta-glucuronidase (GUS) and Basta resistance (BAR) facilitated the identification of plants bearing germinally transposed DsHPT elements. RFLP mapping of 21 transposed DsHPT elements originating from the two different T-DNA insertions revealed distinct patterns of reintegration sites.

Agrobacterium tumefaciens↗
PubMed1994

Solution structure and DNA-binding properties of a thermostable protein from the archaeon Sulfolobus solfataricus.

The archaeon Sulfolobus solfataricus expresses large amounts of a small basic protein, Sso7d, which was previously identified as a DNA-binding protein possibly involved in compaction of DNA. We have determined the solution structure of Sso7d. The protein consists of a triple-stranded anti-parallel beta-sheet onto which an orthogonal double-stranded beta-sheet is packed. This topology is very similar to that found in eukaryotic Src homology-3 (SH3) domains. Sso7d binds strongly (Kd < 10 microM) to double-stranded DNA and protects it from thermal denaturation. In addition, we note that epsilon-mono-methylation of lysine side chains of Sso7d is governed by cell growth temperatures, suggesting that methylation is related to the heat-shock response.

Amino Acid Sequence↗
PubMed1994

A new subtype of human immunodeficiency virus type 1 (MVP-5180) from Cameroon.

A new subtype (MVP-5180) of human immunodeficiency virus type 1 (HIV-1) was isolated from a Cameroonian AIDS patient. MVP-5180 was grown in several human T-cell lines and the monocytic U937 line. MVP-5180 DNA could not be amplified by nested primer PCR with conventional env primers and could be only very faintly amplified with gag and pol primers. Most German, Ivoirian, and Malawian anti-HIV-1 sera reacted faintly or moderately with Env proteins in an MVP-5180 immunoblot, whereas some Cameroonian sera reacted strongly. Of HIV-1-infected Cameroonians, 8% were identified by serological methods as infected with MVP-5180; 7% were positive when MVP-5180-specific PCR env primers were used. DNA sequence analysis of MVP-5180 showed that its genetic organization was that of HIV-1, with 65% similarity to HIV-1 and 56% similarity to HIV-2 consensus sequences. The env gene of MVP-5180 had similarities to HIV-1 and HIV-2 of 53 and of 49%, respectively. V3 loop analysis identified a crown of Gly-Pro-Met-Arg by using cloned DNA and Gly-Pro-Leu-Arg by using PCR-amplified DNA, neither of which configuration has been described for other HIV strains. In an analysis of relationships, MVP-5180 occupied a position distant to all other HIV-1 strains, including the chimpanzee simian immunodeficiency virus type 1 SIVcpz and the Uganda virus U455, and closer to the HIV-1/HIV-2 divergence node. MVP-5180, together with another Cameroonian isolate, ANT-70, constitutes a group subtype O of the most divergent HIV-1 isolates yet identified. Characterization of MVP-5180 is important for understanding the natural history of the primate immunodeficiency viruses and for the development of vaccines and diagnostics.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Two distinct factors bind to the rabbit uteroglobin TATA-box region and are required for efficient transcription.

The rabbit uteroglobin gene is expressed in a variety of epithelial cell types like the lung Clara cells and the glandular and luminal epithelial cells of the endometrium. Expression in Clara cells is on a high constitutive level, whereas expression in the rabbit endometrium is under tight hormonal control. One important element of the rabbit uteroglobin gene mediating its efficient transcription in two epithelial cell lines from human endometrium (Ishikawa) and lung (NCI-H441) is its noncanonical TATA box (TACA). Here, we show that two factors (TATA core factor [TCF] and TATA palindrome factor [TPF]) different from the TATA-box binding protein bind to the DNA major groove at two adjacent sites within the uteroglobin TATA-box region and that one of them (TCF) is specifically expressed in cell lines derived from uteroglobin-expressing tissues. The binding sites for TCF and TPF, respectively, are both required for efficient transcription in Ishikawa and NCI-H441 cells. Mutation of the TACA box, which we show is a poor TATA box in functional terms, to a canonical TATA motif does not affect TCF and TPF binding. Therefore, we suggest that the function of the unusual cytosine could be to reduce rabbit uteroglobin expression in cells lacking TCF and that the interaction of TATA-box binding protein with the weak TACA site is facilitated in TCF- and TPF-positive cells.

Animals↗
PubMed1994

Molecular mechanism of the t(14;18)--a model for lymphoid-specific chromosomal translocations.

The chromosomal translocation t(14;18) occurs during early B-cell development and juxtaposes the immunoglobulin heavy chain locus (IgH) with the bcl-2 oncogene. Several factors contribute to the translocation mechanism: (1) The rearrangement of the chromosome 14 DH and JH translocation partners has typical features of V(D)J-recombinase-mediated joining with N-segment addition. (2) The bcl-2 major (mbr) and minor (mcr) breakpoint regions as well as their IgH reciprocal counterparts contain recombinatorial sequences related to chi or the minisatellite-core which bind at least one common DNA-binding protein (bp45). Similar elements are found at the breakpoints of other lymphoid-specific translocations like the t(11;14), t(2;8) or the t(4;11). (3) Structural analysis of the bcl-2 mbr indicates that this region may adopt alternative DNA-configurations which can promote recombination and is cleaved by an endogenous nuclease present in early B-cells. The present data suggest that V(D)J-recombinase as well as chi/minisatellite-core mediated recombination contribute to the mechanism and make the t(14;18) a model system for lymphoid-specific reciprocal translocations.

Base Sequence↗