Detection of an anatoxin-a(s)-like anticholinesterase in natural blooms and cultures of cyanobacteria/blue-green algae from Danish lakes and in the stomach contents of poisoned birds

Ten natural bloom samples of cyanobacteria from the Danish lakes Knud s? (5), Ravn s? (4), and Salten Langs? (1) collected during 1993-1995 were assayed for toxicity by mouse bioassay, for acetylcholinesterase inhibiting activity by a colorimetric method, and for microcystins by enzyme-linked immunosorbent assay. In the mouse bioassay, seven samples were neurotoxic, two were non-toxic and one gave a protracted toxic response. One of the non-toxic and the single protracted toxic sample both contained anticholinesterase activity equivalent to 4 micrograms anatoxin-a(s) g-1. The neurotoxic samples contained equivalents to 20-3300 micrograms anatoxin-a(s) g-1. The highest anticholinesterase activities (equivalent to 2300 and 3300 micrograms anatoxin-a(s) g-1, respectively) were found in samples collected from Lake Knud s? in connection with bird-kills in 1993 and 1994. Small amounts of microcystins (0.1-0.9 microgram g-1) were detected in all samples but one. All Lake Knud s? and Lake Ravn s? samples were dominated by Anabaena lemmermannii, and the Lake Salten Langs? sample by several species of Anabaena. Gel filtration profiles indicated similarity between the toxic component from the Lake Knud s? 1994 bloom with registered bird-kills and anatoxin-a(s) isolated from Anabaena flos-aquae NRC-525-17. Anticholinesterase-producing cultures of A. lemmermannii were isolated from the Lake Knud s? 1993 bloom. These laboratory cultures produced anatoxin-a(s) equivalents of 29-743 micrograms g-1. Other cultures of A. lemmermannii isolated from Lake Knud s? and Lake Ravn s? were hepatotoxic or non-toxic. Dead birds collected from Lake Knud s? during the neurotoxic 1993 Anabaena bloom possibly died from cyanobacterial toxicosis. The stomach contents contained colonies and single trichomes of Anabaena, and anticholinesterase activities equivalent to 2.1-89.7 micrograms anatoxin-a(s) kg-1 body weight and microcystins (53-95 ng kg-1) were also detected.     

Physical and chemical characteristics of butterfat fractions obtained by crystallization from molten fat

Both summer and winter butterfats were fractionated using a laboratory procedure which was designed to simulate a commercial fractionation process. The process is based on a slow, controlled cooling of the melted fat, a short stabilization time at the fractionation temperature, and separation of the crystals from the liquid oil by vacuum filtration using a stainless steel perforated disc. Fractionation temperatures of 29, 26, 23 and 19 C for winter butterfat and 29 and 19 C for summer butterfat were used to obtain solid and liquid fractions at each temperature. Three replications at each temperature showed good reproducibility of results. The fractions were characterized by their fatty acid and triglyceride compositions, melting and crystallization behavior, iodine value, peroxide value and melting point. Presented at the AOCS meeting in Philadelphia in May 1985.     

Ascorbic acid is a stimulatory cofactor for mitochondrial glycerol-3-phosphate dehydrogenase

We describe in this report a sensitive and direct method for the analysis of tamoxifen (TAM) in microsamples of plasma. The drug and internal standard (quinine bisulfate, I.S.) were separated on a 10-microm particle, 10 cm X 8 mm CN cartridge in conjunction with a radial compression system. The mobile phase was a mixture of 0.1 M sodium acetate in 0.001 M tetrabutylammonium phosphate solution (pH 6) and methanol (30:70, v/v) at a flow-rate of 4 ml/min. After addition of I.S. and o-phosphoric acid in acetonitrile (0.6 M) to the plasma (30 microl), the mixture was placed in an ultraviolet shortwave transluminator for 2 min prior to injection into the chromatograph. The compounds were detected in the effluent fluorometrically at excitation and emission wavelengths of 258 and 378 nm, respectively. Under these conditions, no interference in the assay from any endogenous substance or other concurrently used drugs was observed and the retention times of I.S. and TAM were 4.4 and 10.15 min, respectively. The concentration of TAM in plasma was linearly (r>0.9983) related to the peak height ratio (TAM/I.S.) in the range 0.01-2.0 microg ml(-1) and C.V. at 0.075, 0.4 and 1.2 microg ml(-1) was < or = 4.96%. We are currently using this assay for monitoring TAM in plasma and investigating its pharmacokinetics in cancer patients receiving cytotoxic drugs in addition to TAM as a multi-drug resistance modifier.     

Rotationplasty

Today rotationplasty is well established as an acceptable procedure for limb salvage in patients who have a malignant tumor in the femur or tibia. The main indication is that it is the alternative to amputation. Rotationplasty should further be used in the very young child because of growth-dependent complications that can be expected after tumor resection and any kind of reconstruction. This article covers the classification of the different types of rotationplasties, the operative procedure, prosthetic care, and the functional results.     

Recursive optimal pruning with applications to tree structuredvector quantizers

A pruning algorithm of P.A. Chou et al. (1989) for designing optimal tree structures identifies only those codebooks which lie on the convex hull of the original codebook's operational distortion rate function. The authors introduce a modified version of the original algorithm, which identifies a large number of codebooks having minimum average distortion, under the constraint that, in each step, only modes having no descendents are removed from the tree. All codebooks generated by the original algorithm are also generated by this algorithm. The new algorithm generates a much larger number of codebooks in the middle- and low-rate regions. The additional codebooks permit operation near the codebook's operational distortion rate function without time sharing by choosing from the increased number of available bit rates. Despite the statistical mismatch which occurs when coding data outside the training sequence, these pruned codebooks retain their performance advantage over full search vector quantizers (VQs) for a large range of rates.     

Administration of first-aid and prevention of injuries in Kenyan soccer

Appropriate scientific training demands the cooperation of the coach, player, doctor and physiotherapist. The training process involves the medical examination before a competitive season, the diagnosis and treatment of injuries when they occur, the prevention of injuries and the rehabilitation of the injured back into competitive play. It is in these respects that a coach requires the services of a doctor and/or a physiotherapist on the technical bench. This study therefore attempted to establish whether the soccer coaches were benefiting from the professional support of the doctors. The study sought the views of the Kenyan soccer coaches on the administration of first-aid and the preventive measures against injuries. Specifically, the study attempted to find out whether the Kenyan soccer clubs employed team doctors, whether the coaches had adequate knowledge in first-aid, the injury prevention measures that the coaches enforced, etc. A questionnaire was administered to 42 individual soccer coaches who were attending an advanced Confederation Africaine de Football (CAF) coaching course in Nairobi. Thirty-three (78.57%) were used in the study. The participants were drawn from all the provinces of Kenya except North Eastern. The findings were that 13 (39.4%) of the clubs represented did not have a qualified medical attendant; that in the absence of a team doctor, it is the coach who mostly administered first-aid (42.4%); that out of all the coaches only 15 (45.5%) were well versed in first-aid procedures, among others.(ABSTRACT TRUNCATED AT 250 WORDS)     

A limit analysis of nonlinear elastic lateral displacements of thin-walled reinforced and prestressed beams

An incremental iterative process based on direct energy minimization is presented for a limit analysis of nonlinear elastic lateral displacements and twists of reinforced and prestressed beams. Problems encountered with the constitutive relations are discussed and two possible material models are presented.     

The partial testing design: a less costly way to test equivalence for sensitivity and specificity

We propose a new, less costly, design to test the equivalence of digital versus analogue mammography in terms of sensitivity and specificity. Because breast cancer is a rare event among asymptomatic women, the sample size for testing equivalence of sensitivity is larger than that for testing equivalence of specificity. Hence calculations of sample size are based on sensitivity. With the proposed design it is possible to achieve the same power as a completely paired design by increasing the number of less costly analogue mammograms and not giving the more expensive digital mammograms to some randomly selected subjects who are negative on the analogue mammogram. The key idea is that subjects who are negative on the analogue mammogram are unlikely to have cancer and hence contribute less information for estimating sensitivity than subjects who are positive on the analogue mammogram. To ascertain disease state among subjects not biopsied, we propose another analogue mammogram at a later time determined by a natural history model. The design differs from a double sampling design because it compares two imperfect tests instead of combining information from a perfect and imperfect test.     

Structures stabilizing the dimer interface on human 11 beta-hydroxysteroid dehydrogenase types 1 and 2 and human 15-hydroxyprostaglandin dehydrogenase and their homologs

Human 11 beta-hydroxysteroid dehydrogenase-types 1 and 2 and human 15-hydroxyprostaglandin dehydrogenase belong to a large family of oxidoreductases that includes human dihydropteridine reductase and Streptomyces hydrogenans 20 beta-hydroxysteroid dehydrogenase, for which 3D structures are available. Almost all of these enzymes are either dimers or tetramers. The dimer interface of rat dihydropteridine reductase consists of alpha-helices E and F from each monomer arranged in a four alpha-helix bundle [Varughese et al. (1992) Proc. Natl. Acad. Sci. USA 89, 6080-6084]. Alpha-helix F contains tyrosine-146 and lysine-150, residues that are highly conserved in this protein superfamily and have been proposed to be at the catalytic site. We have examined the dimer interface between alpha-helix F in human and rat dihydropteridine reductase and Streptomyces hydrogenans 20 beta-hydroxysteroid dehydrogenase as well as modeled 3D structures of steroid and prostaglandin dehydrogenases and homologs for stabilizing interactions. We find a site in the middle of alpha-helix F that stabilizes the dimer. This anchor is adjacent to conserved lysine on alpha-helix F. Our analysis suggests that sequence variation in the anchor may be important in substrate specificity.