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Biomedical subjects

R Roth

Publications and source records attributed to R Roth.

At least 55 records · Page 3Linked to original sources
PubMed1999

Hyaluronan synthesis in virus PBCV-1-infected chlorella-like green algae.

We previously reported that the chlorella virus PBCV-1 genome encodes an authentic, membrane-associated glycosyltransferase, hyaluronan synthase (HAS). Hyaluronan, a linear polysaccharide chain composed of alternating beta1,4-glucuronic acid and beta1, 3-N-acetylglucosamine groups, is present in vertebrates as well as a few pathogenic bacteria. Studies of infected cells show that the transcription of the PBCV-1 has gene begins within 10 min of virus infection and ends at 60-90 min postinfection. The hyaluronan polysaccharide begins to accumulate as hyaluronan-lyase sensitive, hair-like fibers on the outside of the chlorella cell wall by 15-30 min postinfection; by 240 min postinfection, the infected cells are coated with a dense fibrous network. This hyaluronan slightly reduces attachment of a second chlorella virus to the infected algae. An analysis of 41 additional chlorella viruses indicates that many, but not all, produce hyaluronan during infection.

Cell Wall↗
PubMed1999

Deconvolution of 40 Hz steady-state fields reveals two overlapping source activities of the human auditory cortex.

Steady-state auditory evoked fields were recorded from 15 subjects using a whole head MEG system. Stimuli were 800 ms trains of binaural clicks with constant stimulus onset asynchrony (SOA). Seven different SOA settings (19, 21, 23, 25, 27, 29 and 31 ms) were used to give click rates near 40 Hz. Transient responses to each click were reconstructed using a new algorithm that deconvoluted the averaged responses to the different trains. Spatio-temporal multiple dipole modelling in relation to 3D MRI scans revealed two overlapping source components in both the left and right auditory cortex. The primary sources in the medial part of Heschl's gyrus exhibited a N19-P30-N40 m pattern. The secondary, weaker sources at more lateral sites on Heschl's gyrus showed a N24-P36-N46 m pattern. When applied to transient middle latency auditory evoked fields (MAEFs) recorded at SOAs of 95-135 ms, the primary sources imaged activities similar to the deconvoluted steady-state responses, but the secondary source activities were inconsistent. Linear summation of the deconvoluted source waveforms accounted for more than 96% of the steady-state variance. This indicates that the primary activity of the auditory cortex remains constant up to high stimulation rates and is not specifically enhanced around 40 Hz.

Acoustic Stimulation↗
PubMed1999

[Comparison of radiation exposure of patients caused by selected interventional and angiography procedures--initial results].

PURPOSE: To determine and judge patient doses caused by selected interventional and angiographic procedures using the "Multiskip" digital C-arm unit. MATERIALS AND METHODS: The dose-area product and the fluoroscopic time were measured for 71 percutaneous transluminal angioplasties (PTA), 33 PTA with stent implantation, and 37 embolizations; in addition, they were also measured for 285 digital subtraction angiographies (DSA). In the case of 13 PTA, 10 embolizations, and 33 DSA the number of radiographs was determined, and the dose-area product was divided into two parts, fluoroscopy and radiography, applying a computer programme. RESULTS: The median values of the dose-area product and the fluoroscopic time amounted to 36 Gy cm2 and 11.5 min for PTA, 131 Gy cm2 and 14.4 min for PTA with stent implantation, 197 Gy cm2 and 24.5 min for embolisation as well as 87 Gy cm2 and 3.7 min for DSA. For the relation between dose-area products caused by fluoroscopy and radiography and the number of radiographs, median values of 0.67 and 70 for PTA, 0.58 and 153 for embolisation as well as 1.35 and 135 for DSA were determined. CONCLUSIONS: To reduce the relatively high patient doses the modification of the C-arm unit is aspired to realize pulsed fluoroscopy and automatic filter selection. Also experimental investigations will be done related to additional filtration and reduction of the image intensifier input dose rate and dose per frame, respectively. Then, the effect of dose reduction caused by these measures will be confirmed in a comparable patient study.

Angiography↗
PubMed1999

[Value of MRI in diagnosis of post-traumatic wrist complaints].

The diagnostic value of MRI in acute and chronic posttraumatic wrist pain will be demonstrated in several clinical cases. The integration of MRI in a diagnostic algorithm is discussed. The indication of MRI is given for suspected complex ligamentous lesions, occult fractures and soft tissue pathologies, in particular with disconcordant clinical and radiological signs. Pathology orientated study protocols are presented. Preoperatively, MRI will be helpful in planning definitive surgical treatment.

Fractures, Bone↗
PubMed1998

Induction and evasion of host defenses by type 1-piliated uropathogenic Escherichia coli.

Virtually all uropathogenic strains of Escherichia coli encode filamentous surface adhesive organelles called type 1 pili. High-resolution electron microscopy of infected mouse bladders revealed that type 1 pilus tips interacted directly with the lumenal surface of the bladder, which is embedded with hexagonal arrays of integral membrane glycoproteins known as uroplakins. Attached pili were shortened and facilitated intimate contact of the bacteria with the uroplakin-coated host cells. Bacterial attachment resulted in exfoliation of host bladder epithelial cells as part of an innate host defense system. Exfoliation occurred through a rapid apoptosis-like mechanism involving caspase activation and host DNA fragmentation. Bacteria resisted clearance in the face of host defenses within the bladder by invading into the epithelium.

Adhesins, Bacterial↗
PubMed1998

The PapC usher forms an oligomeric channel: implications for pilus biogenesis across the outer membrane.

Bacterial virulence factors are typically surface-associated or secreted molecules that in Gram-negative bacteria must cross the outer membrane (OM). Protein translocation across the bacterial OM is not well understood. To elucidate this process we studied P pilus biogenesis in Escherichia coli. We present high-resolution electron micrographs of the OM usher PapC and show that it forms an oligomeric complex containing a channel approximately 2 nm in diameter. This is large enough to accommodate pilus subunits or the linear tip fibrillum of the pilus but not large enough to accommodate the final 6.8-nm-wide helical pilus rod. We show that P pilus rods can be unraveled into linear fibers by incubation in 50% glycerol. Thus, they are likely to pass through the usher in this unwound form. Packaging of these fibers into their final helical structure would only occur outside the cell, a process that may drive outward growth of the pilus organelles. The usher complex appears to be similar to complexes formed by members of the PulD/pIV family of OM proteins, and thus these two protein families, previously thought to be unrelated, may share structural and functional homologies.

Bacterial Outer Membrane Proteins↗
PubMed1998

[Percutaneous therapeutic embolization in therapy refractory, non-traumatic epistaxis].

UNLABELLED: The records of 24 patients with severe intractable non-traumatic epistaxis were reviewed to evaluate the efficacy of embolism therapy. MATERIAL AND METHOD: The histories of 17 patients with idiopathic epistaxis, 6 patients with Osler-Rendu-Weber disease and 1 patient with a high-flow angioma were analyzed. All patients were treated by means of percutaneous embolization of the maxillary artery and its branches. RESULTS: In 5/17 patients with idiopathic epistaxis repeat embolization was necessary in 5 cases, while permanent hemostasis was achieved in 16/17 patients with embolism alone. Five of the 6 patients with Osler-Rendu-Weber disease labelled stage III before treatment were managed successfully with repeated embolizations, while all cases were reduced to stage I disease. The high-flow angioma was successfully ablated after embolization combined with direct injection of thrombosing material and laser resection.

Adult↗
PubMed1998

Subunit composition, protein interactions, and structures of the mammalian brain sec6/8 complex and septin filaments.

Both the sec6/8 complex and septin filaments have been implicated in directing vesicles and proteins to sites of active membrane addition in yeast. The rat brain sec6/8 complex coimmunoprecipitates with a filament composed of four mammalian septins, suggesting an interaction between these complexes. One of the septins, CDC10, displays broad subcellular and tissue distributions and is found in postmitotic neurons as well as dividing cells. Electron microscopic studies showed that the purified rat brain septins form filaments of 8.25 nm in diameter; the lengths of the filaments are multiples of 25 nm. Glutaraldehyde-fixed rat brain sec6/8 complex adopts a conformation resembling the letter "T" or "Y". The sec6/8 and septin complexes likely play an important role in trafficking vesicles and organizing proteins at the plasma membrane of neurons.

Amino Acid Sequence↗
PubMed1998

Rapid and specific detection of toxigenic Staphylococcus aureus: use of two multiplex PCR enzyme immunoassays for amplification and hybridization of staphylococcal enterotoxin genes, exfoliative toxin genes, and toxic shock syndrome toxin 1 gene.

Two multiplex PCR enzyme immunoassays (PCR-EIAs) were developed for Staphylococcus aureus exotoxin gene screening as an alternative to the conventional biological assays, which depend on detectable amounts of toxins produced. One set of oligonucleotide primers and probes was designed to search for enterotoxin A to E genes (entA, entB, entC, entD, and entE), and the other one was designed to detect the staphylococcal exfoliative toxin genes (eta and etb) and the toxic shock syndrome toxin 1 gene (tst). Oligonucleotide primers were used as published previously, modified or newly developed to meet the requirements of both good size-distinguishable amplification bands of multiplex PCR and the temperature limit of the uracil DNA glycosylase system for carryover protection. Amplification products were visualized by agarose gel electrophoresis, and specificity was controlled with the aid of a DNA EIA system using oligonucleotide probes derived from the sequences of the S. aureus toxin genes. PCR procedures were performed by using template nucleic acids extracted from a panel of S. aureus reference strains and from a collection of 50 clinical strains. The PCR results were compared with those of immunological toxin production assays. This multiplex PCR-EIA system offers an alternative method for the rapid, sensitive, specific, and simultaneous detection of the clinically important exotoxin potency of isolated S. aureus strains for diagnostic purposes as well as research studies.

Bacterial Toxins↗
PubMed1998

Cellular differentiation in the maize leaf is disrupted by bundle sheath defective mutations.

The mature maize leaf is characterised by a series of parallel veins that are surrounded by concentric rings of bundle sheath (BS) and mesophyll (M) cells. To identify genes that control cellular differentiation patterns in the leaf, we have isolated a group of mutations that specifically disrupt the differentiation of a single cell type. In maize bundle sheath defective (bsd) mutants, C4 photosynthetic development is perturbed in BS cells while M cells appear to develop normally. Two mutants, bsd1 and bsd2, have been characterised in detail. Analysis of these mutants, and the corresponding Bsd1 and Bsd2 genes is providing an insight into cellular processes regulating photosynthetic cell type differentiation in maize.

Cell Differentiation↗
PubMed1998

Initial Clinical Experience of a Novel Device (the ÒFriend CatheterÓ) for Local Anesthetic Delivery Around Indwelling Arterial Sheaths.

The removal of femoral arterial sheaths, particularly after they have been in place for some hours, is a source of pain for patients undergoing invasiveive cardiac procedures. Methods of reducing this pain include systemic sedatives, analgesics and local anesthetic. We tested a new disposable plastic device, called the ÒFriend,Ó designed to reduce pain associated with sheath removal. The Friend wraps around a standard 8 Fr sheath allowing local anesthetic infiltration through side holes into local tissue. METHODS: Seventy-two patients undergoing interventional procedures were randomized to 3 groups for anesthetic administration just prior to sheath removal. Group 1 (control) received no local anesthetic. Group 2 (local) received 10 ml of lignocaine directly infiltrated with syringe and needle around the sheath. Group 3 (Friend) had the Friend inserted with the sheath and 10 ml of lignocaine was delivered via the device. Pain around the sheath was assessed prior to, during and just after, sheath removal using a 5 point verbal scale. RESULTS: Sixty-two patients completed the study. There were no serious complications related to the Friend device. The Friend group patients had significantly less pain associated with sheath removal than the control group. (Mean pain difference 1.28 vs. 0.34, p = 0.04). Pain scores in group 2 (local) did not differ significantly from the control group. The additional estimated cost involved in using the Friend was $16.93 per patient. CONCLUSIONS: The Friend device is a new, inexpensive and safe method of reducing pain associated with removal of arterial sheaths after cardiac interventional procedures.

Journal Article↗
PubMed1998

[Surgical therapy of dens fracture].

The use of Anderson/D'Alonso or Aebi/Nazarian classification of dens fractures is the basis for exact selection of therapy. The ventral screw-fixation of Anderson type-II-Fracture is today the common standard of treatment, especially in the elderly. The stabilisation of the fracture with maintenance of atlanto-axial rotation-function, the minimal rate of pseudarthrosis compared with conservative therapy, the minimal operation trauma and the immediate mobilisation with high patient comfort are decisive benefits of this method. Reposition of the fracture, visualisation in two planes and the use of adequate instruments are important conditions to get optimal operation results. In-vitro-experiments have shown that there is no difference of stability in one- or two-screw-technique. Flexion injuries with oblique fracture plane, insufficient stability after anterior screw fixation and typ-III-fractures are indications for dorsal, atlanto-axial screw fixation. The conservative treatment(HALO-vest) is recommended only in otherwise inoperable patients.

Bone Screws↗
PubMed1997

Structure and conformational changes in NSF and its membrane receptor complexes visualized by quick-freeze/deep-etch electron microscopy.

Using quick-freeze/deep-etch electron microscopy of recombinant proteins adsorbed to mica, we show that NSF, the oligomeric ATPase involved in membrane fusion, is a hollow 10 x 16 nm cylinder whose conformation depends upon nucleotide binding. Depleted of nucleotide, NSF converts to a "splayed" protease-sensitive conformation that reveals its subunit composition. NSF's synaptic membrane substrate, the ternary SNARE complex containing syntaxin, SNAP-25, and synaptobrevin, is a 4 x 14 nm rod with a "tail" at one end, corresponding to the N-terminus of syntaxin. Using epitope tags, antibodies, and maltose-binding protein markers, we find that syntaxin and synaptobrevin are aligned in parallel in the complex, with their membrane anchors located at the same end of the rod. This SNARE rod binds with alpha-SNAP to one end of the NSF cylinder to form an asymmetric "20S" complex. Together, these images suggest how NSF could dissociate the SNARE complex and how association and dissociation of the complex could be related to membrane fusion.

Adenosine Triphosphatases↗
PubMed1997

B lymphocytes as autoantigen-presenting cells in the amplification of autoimmunity.

The exact role of B cells in antigen presentation to naive T cells in vivo is presently not known. Here, we demonstrate the ability of a B cell subset consisting of B7-2pos-B cells to prime autoreactive T cells in B cell-deficient mice. In contrast, B cell-deficient mice are unable to mount a similar initiation and expansion of the autoimmune response. The expression of the B7-2 costimulatory molecule as well as the specificity to a self-antigen, either murine cytochrome c or murine ribonucleoproteins (the target of autoimmunity in SLE), enabled B cells as antigen-presenting cells to induce naive lymph node T cells to proliferate and to express IFN-gamma, IL-4, IL-5, and IL-10 cytokine mRNAs. In contrast, neither adoptively transferred B7-2neg-B cells nor nonspecific B7-2pos-B cells were able to activate naive T cells. In addition, anti-B7-2 treatment prevented the in vivo expression of the IL-4, IL-5, and IFN-gamma cytokine mRNA responses. Our results suggest a major role of autoantigen-specific B7-2pos-B cells in breaking T cell tolerance to self-antigen.

Animals↗
PubMed1997

An algorithm for assessing intraoperative mean arterial pressure lability.

BACKGROUND: Intraoperative blood pressure lability may be related to risk factors, hypovolemia, light anesthesia, and morbid outcomes, but the measurements of lability in previous studies have been limited by imprecise and infrequent data collection methods. Computerized intraoperative data acquisition systems have provided an opportunity to readdress the issue of intraoperative blood pressure lability with more abundant and precise data. This study sought to derive and validate an algorithm (expert system) to measure mean arterial pressure (MAP) lability. METHODS: Two hundred thirty-nine computerized anesthesis records were reviewed retrospectively. Three anesthesiologists separately rated MAP as very stable, average, or very labile. The parameters of a computer algorithm that measured the change of median MAP between consecutive 2-min epochs were optimized to achieve the best possible agreement among the anesthesiologists. The algorithm was then validated on 229 additional anesthesia records. RESULTS: The proportion of consecutive 2-min epochs in which the absolute value of the fractional change of median MAP exceeded 0.06 (i.e., 6%) correlated strongly with the anesthesiologists' ratings (r = 0.78; P < 0.0001). The optimal sensitivity and specificity of the algorithm for detecting MAP lability were 98% and 59%, respectively. CONCLUSIONS: One potential application of expert systems to anesthesia practice is a "smart alarm" to detect blood pressure lability. It may also provide a better tool to assess the relation between lability and outcome than has been available previously.

Algorithms↗