T-cell epitope mapping by flow cytometry

From March 1994 to September 1996, 39 patients underwent stenting of the unprotected left main coronary artery because of high surgical risk. Stenting appeared to improve clinical outcome, but there was a significant mortality rate at long-term follow-up.     

Posttransplant lymphoproliferative disorder in pediatric bone marrow transplant recipients: disseminated disease of donor origin demonstrated by fluorescence in situ hybridization

Two new antibiotics, hongoquercins A and B, were isolated from fermentation extracts of the unidentified fungus LL-23G227. In the optimum medium, titers of the A and B components reached approximately 2.1 g/liter and 0.02 g/liter, respectively. The optimum temperature for antibiotic production was approximately 22 degrees C. Growth was delayed at 15 degrees C but appeared to reach higher levels than was observed at 22 degrees C. Addition of dextrose to growth media increased hongoquercin B production. Hongoquercin A exhibited moderate activity against Gram-positive bacteria. Mechanistic studies conducted in an E. coli imp strain suggested membrane damage as the primary mode of bactericidal action. These compounds also lysed human red blood cells, suggesting a similar mode of action on eukaryotic cells.     

Seizures associated with propofol anesthesia

Propofol is a new, fast-acting intravenous (i.v.) anesthetic. Involuntary movements or epileptic seizures have occurred during or after propofol-induced anesthesia in approximately 50 reported cases; a third of the patients have had epilepsy. We report 5 patients with seizures in association with propofol anesthesia. A female epileptic patient developed severe status epilepticus; the other patients with short-lasting seizures had no previous epilepsy. Although propofol has been used in treatment of patients of status epilepticus, the risk of precipitation of epileptic seizures warrants consideration especially when planning anesthesia for epileptic patients.     

Surgical treatment of lymphadenopathy in children

Clinical observations of 1365 children with the lymph nodes affection were summarized. The diagnosis verification was conducted using the broad arsenal of general clinical and special methods of investigation. In complicated situations the histochemical and immunogenetic methods were applied for the diagnosis. The structure and dynamics of children's morbidity with lymphadenopathies (LAP) was studied up, the age, sexual and seasonal peculiarities were systematized, the analysis of primary localizations and clinico-morphological comparisons was conducted. The basic thesises of the standardized approach were elaborated on the ground of the diagnostical and tactical mistakes results analysis.     

Substituted glycals as probes of glycosidase mechanisms

D-Glucal and a series of substituted derivatives have been tested as substrates, inhibitors and inactivators of the Agrobacterium faecalis beta-glucosidase in order to probe structure/function relationships in this enzyme. D-Glucal is shown to be a substrate (kcat = 2.3 min-1, Km = 0.85 mM) undergoing hydration with stereospecific protonation from the alpha-face to yield 2-deoxy-beta-D-glucose. 1-Methyl-D-glucal surprisingly serves as only a poor substrate (kcat = 0.056 min-1, Km = 57 mM), also undergoing protonation from the alpha-face. 2-Fluoro-D-glucal, however is completely inert, as a result of inductive destabilisation of the oxocarbenium ion-like transition state for protonation, and functions only as a relatively weak (Ki = 24 mM) inhibitor. Similar behaviour was seen with almond beta-glucosidase and yeast alpha-glucosidase and for the interaction of 2-fluoro-D-galactal with Escherichia coli beta-galactosidase. A series of of alpha, beta-unsaturated glucal derivatives was also synthesised and tested as potential substrates, inhibitors or inactivators of A. faecalis beta-glucosidase. Of these only 1-nitro-D-glucal functioned as a time dependent, irreversible inactivator (ki = 0.011 min-1, Ki = 5.5 mM), presumably acting as a Michael acceptor. Electrospray mass spectrometric analysis revealed multiple labeling of the enzyme by this inactivator, lessening its usefulness as an affinity label. Less reactive Michael acceptor glycals which might have been more specific (1-cyano-, 2-cyano-, 1-carboxylic acid, 1-carboxylic acid methyl ester) unfortunately did not function as inactivators or substrates, only as relatively weak reversible inhibitors (Ki = 3-96 mM).     

Presence and consequence of uracil in preneoplastic DNA from folate/methyl-deficient rats

Uracil can arise in DNA by misincorporation of dUTP into nascent DNA and/or by cytosine deamination in established DNA. Based on recent findings, both pathways appear to be promoted in the methyl-deficient model of hepatocarcinogenesis. A chronic increase in the ratio dUTP:dTTP with folate/methyl deficiency can result in a futile cycle of excision and reiterative uracil misincorporation leading to premutagenic apyrimidinic (AP) sites, DNA strand breaks, DNA fragmentation and apoptotic cell death. The progressive accumulation of unmethylated cytosines with chronic methyl deficiency will increase the potential for cytosine deamination to uracil and further stress uracil mismatch repair mechanisms. Uracil is removed by a highly specific uracil-DNA glycosylase (UDG) leaving an AP site that is subsequently repaired by sequential action of AP endonuclease, 5'-phosphodiesterase, a DNA polymerase and DNA ligase. Since the DNA polymerases cannot distinguish between dUTP and dTTP, an increase in dUTP:dTTP ratio will promote uracil misincorporation during both DNA replication and repair synthesis. The misincorporation of uracil for thymine (5-methyluracil) may constitute a genetically significant form of DNA hypomethylation distinct from cytosine hypomethylation. In the present study a significant increase in the level of uracil in liver DNA as early as 3 weeks after initiation of folate/methyl deficiency was accompanied by parallel increases in DNA strand breaks, AP sites and increased levels of AP endonuclease mRNA. In addition, uracil was also detected within the p53 gene sequence using UDG PCR techniques. Increased levels of uracil in DNA implies that the capacity for uracil base excision repair is exceeded with chronic folate/methyl deficiency. It is possible that enzyme-induced extrahelical bases, AP sites and DNA strand breaks interact to negatively affect the stability of the DNA helix and stress the structural limits of permissible uracil base excision repair activity. Thus substitution of uracil for thymine induces repair-related premutagenic lesions and a novel form of DNA hypomethylation that may relate to tumor promotion in the methyl-deficient model of hepatocarcinogenesis.