Kernels of the wheat class DNS were stored for 21 months at 20°C. Flours were milled before (I) and after storage (II). Doughs from II were firmer than those from I, possibly due to the decrease of reduced glutathione (GSH) from 124 to 30 nmol/g. The two flours, as well as doughs that were prepared by the addition of GSH, oxidised glutathione (GSSG) and ascorbic acid (AA), were fractionated into albumin, globulin, gliadin, and acid-extractable and acid unextractable glutenin. During kneading of flour-water doughs, endogenous GSH was preferentially bound to the acid-extractable glutenin leading to an increase of protein-glutathione mixed disulphide (PSSG). Whereas addition of GSH to a dough enhanced the amount of PSSG in the acid-unextractable glutenin. GSSG increased the extensibility of the doughs but to a lesser extent than GSH and was mainly bound to the acid-extractable glutenin, most likely by an SS/SH interchange reaction with the SH groups of the proteins. GSH and GSSG, both in the presence of AA, also became bound into the glutenin but without an impairment of the improver action of AA on dough rheology. It is discussed that the addition of AA leads to a rapid conversion of GSH into GSSG, which then becomes attached to the glutenin. The increase of total non-peptide bound cysteine (PSSC) in the acid-extractable glutenin, which was favoured by AA, can be explained by a reaction of endogenous cystine with protein SH groups.
Zinc sulfide can be precipitated quantitatively from solutions buffered at pH 2 using thioacetamidehydrazine hydrochloride mixtures as precipitants. Optimum results are obtained using equimolar quantities of thioacetamide and hydrazine hydrochloride. Coprecipitation of cobalt sulfide was studied using citrate-citric acid, and sulfate-bisulfate buffers. Optimum separations are achieved using a sulfate-bisulfate buffer containing ammonium thiocyanate.
Following up on the recent finding that mesophyll protoplasts of wheat and oats were able to reenter the cell cycle when cultured in vitro, the behaviour of the cytoskeleton was studied. The aim was to elucidate whether changes in the cytoskeletal patterns correlate with the abnormal progression through the cycle observed previously.
RP-separation with TFA-based water/acetonitrile eluents is widely used for peptides and small proteins but is well known difficult for large or membrane proteins. Especially in proteomics or other complex biological matrices reliable elution patterns are difficult to achieve. New commercial stationary phases are validated regarding long term stability, protein recovery, carry over, symmetry and selectivity using 10 different proteins with different molar weights, isoelectric points and glycosylation. It could be demonstrated that some stationary phases had poor protein elution performances. They did not elute a protein at all or with minor recovery, peak symmetries. Sometimes bad and formidable carry over effects for peak areas in the following run were observed. Selectivity in separation of different isomers or glycosylated proteins is also different. The results suggest that neither surface area nor pore diameter play an important role in the application of reversed phases for HPLC of proteins. The investigations leads one to suppose that the bonding chemistry seems to be an important aspect. Most critical fact is that some RP-phases did not elute a protein at all others only 20% of the injected protein mass, which makes the objective of an RP-chromatogram highly questionable.
The non-stoichiometry of zirconium tetramandelate precipitates is explained by the presence of basic salts of varying composition. For reproducible results the zirconium tetramandelate should be precipitated from hot. strongly acid solution by the dropwise addition of mandelic acid.
The use of cryotherapy for the reduction of postoperative swelling and pain has become commonplace in orthopedic, podiatric, and cosmetic surgery. Prolonged exposure to extreme cold may induce an injury nearly identical to that of frostbite. The authors report on 2 patients who underwent podiatric orthopedic surgery and were exposed to prolonged cold therapy, which resulted in limb-threatening problems. Both patients had prolonged and essentially uninterrupted application of cryotherapy for 4 to 7 days, resulting in rewarming injuries of tissue necrosis. A team of specialists used limb salvage therapy to successfully treat the patients. Because of the problems encountered with the cold therapy devices, the authors caution against unmonitored and prolonged cold exposure. Newer devices that prevent cold exposure below 65°F for longer than 2 hours could be a better option in cases in which cryotherapy is used. Level of Evidence: 4.
DOI : 10.1053/j.jfas.2009.06.003 Anahtar Kelimeler :
cold, cryotherapy, frostbite, ischemic, limb savage
Cilt: 48 Sayı: 5 Sayfa: 577-580 ISSN: 1067-2516
We investigate the coherent transient phenomena of excitons in a free-standing ZnSeZnS0.04Se0.96 layer structure, containing an 80 nm thick ZnSe film, by means of subpicosecond time-integrated four wave mixing. We find dephasing times in the order of 0.5 ps for the homogeneously broadened free heavy-hole exciton at 10 K. The dephasing time shows a dependence on the excitation intensity according to the influence of exciton-exciton scattering processes. Simultaneous excitation of the heavy- and light-hole excitons leads to the appearance of coherent interference phenomena which can be assigned to a quantum beat. The spectrally resolved four-wave mixing signal reveals new coherent structures when the ZnSSe exciton is additionally excited. The appearing signals are attributed to polarization interferences between the ZnSSe exciton and the strain split heavy- and light-hole exciton in the ZnSe layer.
A method is described for the potentiometric titration of milligram quantities of the uranium(IV) ion in the presence of iron. This is accomplished by complexing the iron with 1.10-phcnanthroline. The uranium can then be titrated with standard ceric sulfate without interference from the iron.