High-pressure liquid chromatographic and spectrophotometric assays for theophylline in biological fluids

The analysis of theophylline and other xanthine derivatives in biological fluids was examined by high-pressure liquid chromatography (HPLC) and spectrophotometric (Schack and Waxler) methods. An HPLC analysis technique involving precipitation of serum proteins using trichloroacetic acid, injection of the supernatant onto a strong cation exchange column and detection using ultraviolet absorbance provides a nonpolluting, micronized, rapid and reasonably sensitive and specific method for measuring serum theophylline concentrations during clinical pharmacokinetic monitoring. Pre-extration of xanthines with chloroform increases the sensitivity and specificity of the assay. Good agreement was found in the assay results between the spectrophotometric and HPLC assays in 23 of 25 patient specimens, but occasional severe interferences were found with the former technique.     

Capillary electrophoresis chips with integrated electrochemical detection

Porokeratotic eccrine ostial and dermal duct naevus (PEODDN) is a rare, benign hamartomatous malformation involving the eccrine sweat duct. The existence of filiform keratinous plugs that represent cornoid lamellae overlying dilated infundibula of eccrine ducts is a distinctive feature and the presence of associated abnormal dermal ducts is frequent. We report a patient with PEODDN who exhibited lesions on the left side of her chest. Cases of PEODDN reported in the literature are reviewed. Our experience in treating this patient with ultrapulsed carbon dioxide laser is also presented.     

Multiplexed DNA sequencing and diagnostics by hybridization with enriched stable isotope labels

A new DNA diagnostic and sequencing system has been developed that uses time-of-flight resonance ionization mass spectrometry (TOF-RIMS) to provide a rapid method of analyzing stable isotope-labeled oligonucleotides in form 1 sequencing by hybridization (SBH). With form 1, the DNA is immobilized on a nylon membrane and enriched isotope-labeled individual oligonucleotide probes are free to seek out complementary DNAs during hybridization. The major advantage of this new approach is that multiple oligonucleotides can be labeled with different enriched isotopes and can all be simultaneously hybridized to the genosensor matrix. The probes can then be simultaneously detected with TOF-RIMS with high selectivity, sensitivity, and efficiency. By using isotopically enriched tin labels, up to 10 labeled oligonucleotides could be examined in a single hybridization to the DNA matrix. Greater numbers of labels are available if rare earth isotopes are employed. In the present study, matrices containing three different DNAs were prepared and simultaneously hybridized with two different probes under a variety of conditions. The results show that DNAs, immobilized on nylon surfaces, can be specifically hybridized to probes labeled with different enriched in isotopes. Discrimination between complementary and noncomplementary sites of better than 100 was obtained in multiplexed samples. This new SBH method, which employs stable isotopic labels to locate target DNAs and TOF-RIMS to detect the labels, will be a very versatile and extensive multiplexing method.     

Production and dosimetry of copper L ultrasoft x-rays for biological and biochemical investigations

Ultrasoft x-rays provide a unique tool for investigating the intracellular mechanisms of radiation action. Secondary electrons are produced with a well defined energy and a range comparable with that of critical structures in the cell. Copper L characteristic x-rays of weighted average energy of 956 eV interact within the cell, mainly with the oxygen atom, typically producing a photoelectron with energy 424 eV (95%) followed by an Auger electron with an average energy of 505 eV, with a combined continuous slowing down approximation (csda) range of approximately 40 nm. The attenuation through the cell is similar to that of carbon K x-rays (277 eV, single electron), therefore a useful comparison can be made due to similar dose-averaging factors but different electron configurations (total range, and pairs versus singlets). The production, absorption, dosimetry and biological implications of Cu L x-rays using the Medical Research Council cold cathode source is described extending the number of energies available for study in the ultrasoft region. Design parameters were optimized to overcome the inherently low L-characteristic-to-bremsstrahlung yield ratio. Surface absorbed dose rates of 1 Gy min-1 have been obtained with a bremsstrahlung contamination of less than 0.5%. A confocal microscope was used to make thickness measurements on live cells to allow careful determination of the mean absorbed dose. Survival curves for V79-4 Chinese hamster cells were obtained, showing that Cu L x-rays are substantially more lethal per unit dose than are hard x-rays or gamma-rays, with a relative biological effectiveness (RBE) of 1.8. The data are consistent with the hypothesis that clustered damage at the DNA/chromatin level produced by low-energy electrons is biologically more effective.     

Bearing materials from steel chips

Powder Metallurgy and Metal Ceramics -     

Syntheses, biochemical and biological evaluation of staurosporine analogues from the microbial metabolite rebeccamycin

The indolocarbazole antibiotics staurosporine and rebeccamycin (1) are potent antitumor drugs targeting protein kinase C and topoisomerase I, respectively. To obtain staurosporine analogues from rebeccamycin, different structural modifications were performed: coupling of the sugar moiety to the second indole nitrogen, dechlorination and then reduction of the imide function to amide. The newly synthesized compounds (3-6) were tested for their abilities to bind to DNA and to inhibit topoisomerase I and protein kinase C. Their antiproliferative effects in vitro against B16 melanoma and P388 leukemia (including the related P388CPT cell line resistant to camptothecin) as well as their anti-HIV-1 and antimicrobial activities against various strains of microorganisms were determined. The cytotoxicity of the dechlorinated imide analogue 5 correlates well with its DNA binding and anti-topoisomerase I activities. These findings provide guidance for the development of new topoisomerase I-targeted antitumor indolocarbazoles equipped with a carbohydrate attached to the two indole nitrogens.     

Efficient methods of processing metal chips

The development and use of efficient methods of processing chips (particularly alloy chips) is important for solving the problems of conserving resources, improving quality of the metal that is produced, and improving the environmental situation at metallurgical plants.     

Stockpiling and processing alloy steel chips

All-Union Scientific Research and Planning Institute of the State Trust for the Procurement and Processing of Secondary Ferrous Metals (VNIPIvtrochermet). Translated from Metallurg, No. 9, pp. 33–34, September, 1990.     

Vitamin B2 interference with TDx drugs-of-abuse assays

Partially purified hot-water extracts of the roots of plants of the Sophora family suppressed the increase in blood glucose concentration of rats in the oral sugar tolerance test. The extracts also inhibited rat intestinal sucrase and maltase. The most potent sample was about 15 times more active than catechin, a positive control, in these experiments.     

Monitoring of bone turnover biological, preanalytical and technical criteria in the assessment of biochemical markers

A review is given summarizing the present knowledge of bone turnover markers with special emphasis on biological, preanalytical and technical criteria in the proper judgement of efficacy and limitations of the methods employed. The marker substances may be either measures of bone formation or bone resorption. Markers of bone formation are bone alkaline phosphatase, osteocalcin and the carboxyl-terminal propeptide of procollagen type I. Bone alkaline phosphatase has proved to be superior to total alkaline phosphatase activity with respect to diagnostic sensitivity and specificity. Immunochemical techniques for measuring bone alkaline phosphatase show a cross-reactivity of 14-20% with liver alkaline phosphatase. However, this does not compromise the clinical usefulness of these assays except for patients with severe liver diseases. Osteocalcin is strictly bone-specific but shows numerous disadvantages with respect to apparent instability and discordant results as obtained by different methods; however, in certain diagnostic situations (corticosteroid-induced osteopenia, absence of destroyed bone architecture) osteocalcin may serve as a sensitive bone turnover marker. The carboxyl-terminal propeptide of procollagen type I generally shows low discriminating power in the diagnosis of bone diseases. The urinary excretion of pyridinium cross-links' has been carefully evaluated so far with respect to analytical performance and clinical usefulness. This marker may be a substitute for 4-hydroxyproline measurements as the method of choice for assessment of bone resorption. There are other degradation products from the telopeptide regions of bone-derived collagen type I which are excreted into the urine (N-telopeptides, CrossLapsTM); these analytes are promising tools in the assessment of bone resorption but require further evaluation, in particular with respect to their extraskeletal clearance and putative origin outside bone. Moreover, their clinical usefulness may vary depending on the patient group examined. In contrast, the serum concentration of the cross-linked telopeptide region of collagen type I seems to lack both diagnostic specificity and sensitivity in the majority of patient groups. Tartrate-resistant acid phosphatase (as determined by the presently available methods) cannot be recommended as a routine tool for assessment of bone resorption.     

Response of biochemical markers of bone turnover to hormone replacement therapy: impact of biological variability

Biochemical markers of bone turnover may be useful to monitor patients taking hormone replacement therapy (HRT). The aim of this study was to assess the utility of markers in monitoring HRT by comparing the response of a large panel of markers to HRT with their within subject variability. We measured the response of markers to transdermal estradiol in 11 postmenopausal women over 24 weeks. We measured the within subject variability of markers in 11 untreated healthy postmenopausal women over the same period. The mean decrease in markers of bone formation after 24 weeks treatment ranged from 19% for procollagen type I C-terminal propeptide (PICP) to 40% for procollagen type I N-terminal propeptide (PINP). The mean decrease in markers of bone resorption ranged from 10% for tartrate-resistant acid phosphatase (TRAP) to 67% for C-terminal cross-linked telopeptide The least significant change (LSC at p < 0.05), calculated from the within subject variability in the untreated group, was used to define response. LSC for osteocalcin was 21%, bone alkaline phosphatase 28%, PICP 24%, PINP 21%, type I collagen telopeptide 28%, TRAP 17%, urinary calcium 90%, hydroxyproline 75%, total deoxypyridinoline 47%, free pyridinoline 36%, free deoxypyridinoline 26%, N-terminal cross-linked telopeptide 70%, and C-terminal cross-linked telopeptide 132%. The greatest number of responders after 24 weeks of treatment were found using PINP and osteocalcin (9 each), and free deoxypyridinoline (8 each) and total deoxypyridinoline (8 each) and total deoxypyridinoline (7 each). Lumbar spine bone mineral density defined four patients as responders. The ability to detect a response differs between markers and is not dependent on the magnitude of response to therapy.