A bioenergetic model for simulating athletic performance of intermediate duration

Simulating factors affecting human athletic performance, including fatigue, requires a dynamic model of the bioenergetic capabilities of the athlete. To address general cases, the model needs inputs, outputs, and states with a set of differential equations describing how the inputs affect the states and outputs as functions of time. We improve an existing phenomenological muscle model, removing unnecessarily fast dynamic behavior, adding force–velocity dependence, and generalizing it to task level activities. This makes it more suitable for simulating and calculating optimal strategies of athletic events of medium duration (longer than a sprint but shorter than a marathon). To examine the validity and limitations of the model, parameters have been identified from numerical fits to published experimental data.     

Detection of oxidized and reduced glutathione with a recycling postcolumn reaction

A rapid, sensitive, and selective method for the quantitation of both oxidized (GSSG) and reduced (GSH) glutathione in biological materials is described. Oxidized and reduced glutathione are resolved by anion-exchange high-performance liquid chromatography and detected with an in-line, recycling postcolumn reaction. The recycling reaction specifically amplifies the response to oxidized and reduced glutathione 20-100 times over that obtained with a stoichiometric reaction, permitting the detection of 2 pmol glutathione. Oxidized and reduced glutathione levels were measured in rat liver and in dog heart mitochondria. Special precautions are necessary to avoid artifacts which lead to either underestimation or overestimation of GSSG levels. GSH/GSSG ratios of approximately 100-300 were observed in samples prepared from rapidly frozen rat liver. Somewhat higher GSH/GSSG ratios were observed in isolated dog heart mitochondria.     

Amino acid sequence of the beta-chain of the tetrameric haemoglobin of the bivalve mollusc, Anadara trapezia

The amino acid sequence of the beta-chain of the principal haemoglobin from A. trapezia has been determined. The sequence was deduced from the sequences of tryptic peptides, which were fractionated using highperformance liquid chromatography and peptide mapping. Additional sequence data, particularly for the large tryptic peptides, was obtained from enzyme digests of both cyanogen bromide fragments and large citraconyltryptic peptides. The beta-chain has 151 residues which is longer than all the other sequenced haemoglobin chains except the alpha-chain of A. trapezia, which is 153 residues in length. The residues corresponding to those normally in the D helix are absent in this beta-chain. The additional residues are contributed by an extension of the N-terminal region, which was also found to be acetylated. Comparison of the beta-chain amino acid sequence with that of the alpha-chain of A. trapezia, the dimeric chain of A. trapezia, and the dimeric chain of A. broughtonii showed 53% identity in each case. In the E and F helices, the homology is particularly noticeable. There is 100% homology in the F helix of all four chains. The dimeric globin of A. trapezia also shows 100% homology with the beta-chain in the E helix, while the alpha-chain shows 75%. If the tertiary structure of the alpha- and beta-chains of A. trapezia haemoglobin is the same as that of horse haemoglobin, then there are many changes in the alpha 1 and beta 2 contact site residues.     

A Genetic Linkage Map of Mouse Chromosome 10: Localization of Eighteen Molecular Markers Using a Single Interspecific Backcross

Interspecific mouse backcross analysis was used to generate a molecular genetic linkage map of mouse chromosome 10. The map locations of the Act-2, Ahi-1, Bcr, Braf, Cdc-2a, Col6a-1, Col6a-2, Cos-1, Esr, Fyn, Gli, Ifg, Igf-1, Myb, Pah, pgcha, Ros-1 and S100b loci were determined. These loci extend over 80% of the genetic length of the chromosome, providing molecular access to many regions of chromosome 10 for the first time. The locations of the genes mapped in this study extend the known regions of synteny between mouse chromosome 10 and human chromosomes 6, 10, 12 and 21, and reveal a novel homology segment between mouse chromosome 10 and human chromosome 22. Several loci may lie close to, or correspond to, known mutations. Preferential transmission of Mus spretus-derived alleles was observed for loci mapping to the central region of mouse chromosome 10.     

Communication between the corpus cavernosum penis and the corpus spongiosum penis in a bull diagnosed by modified contrast cavernosography: A case report

Traditional methods of penile cavernosography failed to reveal a vascular defect or shunt from the corpus cavernosum penis of a 6-yr-old Brahman bull with a history of acquired failure of penile erection. When a tourniquet was applied to the penis and the contrast medium was introduced into the corpus cavernosum penis under pressure, however, a communication between the corpus cavernosum penis and corpus spongiosum penis was demonstrated. In a normal bull, cavernosography with the introduction of contrast medium under pressure produced a normal radiographic appearance. It is suggested that modification of accepted techniques of cavernosography to incorporate injection of contrast medium under pressure is useful in diagnosing this particular type of vascular abnormality, and may also aid in the detection of smaller vascular shunts from the corpus cavernosum penis to the superficial penile vasculature.     

Novel cloning vectors for Bacillus thuringiensis

Seven replication origins from resident plasmids of Bacillus thuringienis subsp. kurstaki HD263 and HD73 were cloned in Escherichia coli. Three of these replication origins, originating from plasmids of 43, 44, and 60 MDa, were used to construct a set of compatible shuttle vectors that exhibit structural and segregational stability in the Cry- strain B. thuringiensis HD73-26. These shuttle vectors, pEG597, pEG853, and pEG854, were designed with rare restriction sites that permit various adaptations, including the construction of small recombinant plasmids lacking antibiotic resistance genes. The cryIA(c) and cryIIA insecticidal crystal protein genes were inserted into these vectors to demonstrate crystal protein production in B. thuringiensis. Introduction of a cloned cryIA(c) gene from strain HD263 into a B. thuringiensis subsp. aizawai strain exhibiting good insecticidal activity against Spodoptera exigua resulted in a recombinant strain with an improved spectrum of insecticidal activity. Shuttle vectors of this sort should be valuable in future genetic studies of B. thuringiensis as well as in the development of B. thuringiensis strains for use as microbial pesticides.     

Effects of hypoxia on contractility of isolated fetal lamb cerebral arteries

We studied the contractile properties of isolated cerebral arteries in near term fetal lambs, as well as the magnitudes and rates of relaxation during moderate hypoxia. Paired 5-mm segments of basilar, middle cerebral, posterior communicating, and common carotid arteries were suspended in a temperature controlled bath and isometric tension measured during 122 mM K(+)-induced contractions. In one vessel of each pair hypoxia was imposed by switching the bubbling gas from 95% O2 + 5% CO2 to 95% N2 + 5% CO2 4 minutes into a K+ contraction, thus lowering the bath PO2 to approximately 15 Torr. After 15 min exposure to hypoxia the middle cerebral artery had relaxed 61%, the posterior communicating 46%, the basilar 44%, and the common carotid only 18% compared to normoxic controls. All cerebral arteries relaxed relatively rapidly (relaxation rates of 42-45 x 10(-4) s-1), whereas the common carotid relaxed slowly (20 x 10(-4) sec-1). The data indicate that these cerebral arteries play an important role in regulating blood flow responses during hypoxemia in intact fetuses.