The relation between hip impact velocity and hip impact force differs between sideways fall techniques.

Fall techniques that reduce fall severity may decrease the risk of hip fractures. A fundamental variable for fall severity is impact force, but impact velocity is also used. The purpose of the study was to determine whether impact velocity is valid to determine differences in fall severity between different techniques. Five young adults with martial arts (MA) experience performed sideways falls from kneeling height using three techniques: Block with arm (Block) and MA techniques with and without use of the arm to break the fall. In addition, one subject also performed MA falls from standing height. Linear regression analysis showed a moderate relation between hip impact velocity and force, which was depended on technique. In falls with comparable impact velocities, forces in MA falls were lower than forces in Block falls. Hence, differences in impact force could not be predicted by velocity. In conclusion, hip impact velocity may be useful to make an approximate prediction of impact force within fall techniques. However, to determine differences between techniques it was not always a valid predictor. When direct impact force measurements are not possible, methods combining impact velocity with energy estimates before and after impact might be more valid.     

NAD(P)+-independent aldehyde dehydrogenase from Pseudomonas testosteroni. A novel type of molybdenum-containing hydroxylase

Aldehyde dehydrogenase from Pseudomonas testosteroni was purified to homogeneity. The enzyme has a pH optimum of 8.2, uses a wide range of aldehydes as substrates and cationic dyes (Wurster's blue, phenazine methosulphate and thionine), but not anionic dyes (ferricyanide and 2.6-dichloroindophenol), NAD(P)+ or O2, as electron acceptors. Haem c and pyrroloquinoline quinone appeared to be absent but the common cofactors of molybdenum hydroxylases were present. Xanthine was not a substrate and allopurinol was not an inhibitor. Alcohols were inhibitors only when turnover of the enzyme occurred in aldehyde conversion. The enzyme has a relative molecular mass of 186,000, consists of two subunits of equal size (Mr 92,000), and 1 enzyme molecule contains 1 FAD, 1 molybdopterin cofactor, 4 Fe and 4 S. It is a novel type of NAD(P)+-independent aldehyde dehydrogenase since its catalytic and physicochemical properties are quite different from those reported for already known aldehyde-converting enzymes like haemoprotein aldehyde dehydrogenase (EC 1.2.99.3), quino-protein alcohol dehydrogenases (EC 1.1.99.8) and molybdenum hydroxylases.     

Immunotargeting of daunomycin to localized and metastatic human colon adenocarcinoma in athymic mice

Summary A monoclonal antibody (designated SF25), which recognizes a protein antigen expressed on a large number of human colon carcinomas, was used for drug targeting. Daunomycin-antibody conjugates were prepared by two previously described procedures. In one, the drug was bound to the antibody through a spacer of small molecular mass (cis-aconitic acid), while in the other a dextran bridge served as the link between drug and antibody. High substitution rates of drug to antibody were obtained using the latter binding procedure. Both conjugates were tested in vitro against two human colon carcinoma cell lines, LS180 and KM-12. The efficacy of a daunomycin-dextran-SF25 antibody conjugate was tested against colon carcinoma LS180 tumors transplanted at different sites into athymic mice. The specific conjugate was significantly more inhibitory to a subcutaneous tumor growth than its components or their mixture. SF25 antibody alone showed antitumoral effects against all three forms of transplanted tumor tested, namely, local, metastatic or intrahepatic, whereas daunomycin, on its own, was effective only against the subcutaneous tumor. Binding of daunomycin to dextran partially improved its inhibitory activity against the metastatic tumor. The conjugate, daunomycin-dextran-SF25 antibody reduced the number of metastatic foci, increased the survival rate and delayed death. Yet against lymph node metastases it was not significantly better than a mixture of both constituents. However, results obtained with an intrahepatic tumor, a model that mimics the natural progression of the disease, resembled those described with the subcutaneous tumor. Daunomycin-dextran-SF25 antibody was significantly more effective than all components separately and than a mixture of drug and antibody, provided a highly drug-substituted conjugate was used.     

Kinetic analysis of short-term effects of alpha-agonists on gluconeogenesis in isolated rat hepatocytes

Isolated hepatocytes from fasted rats were perifused with glycerol as gluconeogenic substrate. Stimulation of gluconeogenesis with phenylephrine (10(-5) M) as alpha-adrenergic agonist consisted of two distinct phases. The first phase was a transient stimulation of gluconeogenesis and was accompanied by transient changes in cytosolic and mitochondrial redox state; this phase was abolished by the transaminase inhibitor aminooxyacetate. The second phase was a stable stimulation of less magnitude, without change in redox state and insensitive to addition of aminooxyacetate. It is concluded that the first phase is due to a transient enhancement of flux through the malate/aspartate shuttle and that the stable phase is probably due to a stimulation of mitochondrial glycerol-3-phosphate dehydrogenase and glycerol kinase.     

Release of Inorganic Phosphate from Irradiated Yeast: Radiation Biodosimetry and Evaluation of Radioprotective Compounds

When cells of bakers' yeast, Saccharomyces cerevisiae, were irradiated with ionizing radiation, inorganic phosphate, ninhydrin-reactive material, and substances absorbing at 260 mmu were released into the suspending medium. The amount of inorganic phosphate released depended on the radiation dose and on the temperature and pH during irradiation. The concentration of yeast cells did not affect the phosphate yield per milligram of yeast. It is suggested that the release of phosphate may serve as an index of the total radiation environment (i.e., as a biodosimeter) where radiation inactivation of microrganisms is of primary importance, e.g., in radiation preservation of foods. The somewhat limited range of the yeast biodosimeter (ca. 0.5 to 1.75 Mrad) may be extended by use of other more resistant microorganisms, such as bacterial spores. Compounds which have been reported as protecting microorganisms and mammals against the lethal effect of ionizing radiation also inhibited the radiation-induced release of inorganic phosphate from yeast. This phosphate release system is proposed as the basis for an economical, rapid supplement to screening procedures in the evaluation of radioprotective compounds.     

Photocontrol of somatic embryogenesis and polyamine content in Araujia sericifera petals

The effects of photoperiod and end-of-day phytochrome control on somatic embryogenesis and polyamine (PA) content in Araujia sericifera petals have been studied. Petals from immature flowers were cultured under 16- and 8-h photoperiods. Far red (FR), red (R) and FR followed by R light treatments were applied at the end of the photoperiods for three weeks. The number of somatic embryos, callus weight and the levels of free and bound PAs in the cultured petal explants were determined 40 days after the beginning of light treatments. Long day (LD) promoted somatic embryogenesis but did not have any significant effect on PA content. Short day (SD) reduced somatic embryogenesis and enhanced total PAs, mainly in the form of bound spermidine. End-of-day FR treatment increased PA content and inhibited somatic embryogensis under LD but had no significant effect under SD. This effect of FR on PA levels was cancelled by R and was independent of the presence of silver thiosulphate in the medium. End-of-day R treatment reduced the total PA content under SD. However, end-of-day R increased or reduced somatic embryogenesis under SD depending on the presence or absence of silver in the medium. The results suggest a photoperiodic control of somatic embryogenesis and PA content in A. sericifera. The effects of end-of-day R and FR treatments depend on the length of the photoperiod. This finding and the FR/R photoreversibility of end-of-day treatments indicate that phytochrome may be involved in both somatic embryogenesis and accumulation of PA.