Use of Irradiated Amnion as a Biological Dressing in the Treatment of Radiation Induced Ulcers

The management of moist skin desquamation (ulceration) following radiation therapy has been a concern since the inception of this therapy. The treatment of skin reactions focuses on promoting healing, improving patient comfort preventing infection and decreasing trauma to the area. Various dressings like topical preparations, hydrocolloid and gentian violet 1 % dressing have been used for its treatment. We present our experience with the use of amnion as a biological dressing in patients with radiation induced ulceration following pelvic radiation using megavoltage beam. The preliminary experience with treatment in 14 patients proved to be cost effective due to a shorter duration of ulcer healing (median of 7 days), fewer dressing changes (median of 4 dressings) and diminished use of analgesics.     

Identification of a Ras palmitoyltransferase in Saccharomyces cerevisiae

Most Ras proteins are posttranslationally modified by a palmitoyl lipid moiety through a thioester linkage. However, the mechanism by which this occurs is not known. Here, evidence is presented that the Ras2 protein of Saccharomyces cerevisiae is palmitoylated by a Ras protein acyltransferase (Ras PAT) encoded by the ERF2 and ERF4 genes. Erf2p is a 41-kDa protein localized to the membrane of the endoplasmic reticulum and contains a conserved DHHC cysteine-rich domain (DHHC-CRD). Erf2p co-purifies with Erf4p (26 kDa) when it is expressed in yeast or in Escherichia coli. The Erf2p/Erf4p complex is required for Ras PAT activity, and mutations within conserved residues (Cys(189), His(201), and Cys(203)) of the Erf2p DHHC-CRD domain abolish Ras PAT activity. Furthermore, a palmitoyl-Erf2p intermediate is detected suggesting that Erf2p is directly involved in palmitate transfer. ERF2 and ERF4 are the first genes identified that encode a palmitoyltransferase for a Ras GTPase.     

Aqueous and solid complexes of iron(III) with hyaluronic acid. Potentiometric titrations and infrared spectroscopy studies

The coordination of iron(III) ion to hyaluronic acid (Hyal) in aqueous solutions and solid state was accomplished by potentiometric titrations and infrared spectroscopy. The potentiometric titration studies provided the binding constants for the complexes found in the systems and the speciation of these species according to the variation of pH values. The complexes found presented a complexing ability through both the chelating moieties of Hyal (via the N-glucosamine and D-glucoronic acid), showing no special preference for either one while in solid state, but when in aqueous solution the complexation via the N-glucosamine moiety was the preferred, forming two complexed species, ML and ML(2) (log K(ML)=8.2 and log K(ML2)=7.9). The presence of a mu-oxo complex via the D-glucoronic acid was also detected in both aqueous (log K=6.7) and solid states via the N-glucosamine and D-glucoronic acid simultaneously linked to two Hyal chains. A structure for this latter complex was suggested. The results indicated that these complexes could be used in eliminating the excess iron(III) in living organisms.     

Modelling the species richness distribution of French dung beetles (Coleoptera, Scarabaeidae) and delimiting the predictive capacity of different groups of explanatory variables

Aim To predict French Scarabaeidae dung beetle species richness distribution, and to determine the possible underlying causal factors. Location The entire French territory has been studied by dividing it into 301 grid cells of 0.72 × 0.36 degrees. Method Species richness distribution was predicted using generalized linear models to relate the number of species with spatial, topographic and climate variables in grid squares previously identified as well sampled (n = 66). The predictive function includes the curvilinear relationship between variables, interaction terms and the significant third‐degree polynomial terms of latitude and longitude. The final model was validated by a jack‐knife procedure. The underlying causal factors were investigated by partial regression analysis, decomposing the variation in species richness among spatial, topographic and climate type variables. Results The final model accounts for 86.2% of total deviance, with a mean jack‐knife predictive error of 17.7%. The species richness map obtained highlights the Mediterranean as the region richest in species, and the less well‐explored south‐western region as also being species‐rich. The largest fraction of variability (38%) in the number of species is accounted for by the combined effect of the three groups of explanatory variables. The spatially structured climate component explains 21% of variation, while the pure climate and pure spatial components explain 14% and 11%, respectively. The effect of topography was negligible. Conclusions Delimiting the adequately inventoried areas and elaborating forecasting models using simple environmental variables can rapidly produce an estimate of the species richness distribution. Scarabaeidae species richness distribution seems to be mainly influenced by temperature. Minimum mean temperature is the most influential variable on a local scale, while maximum and mean temperature are the most important spatially structured variables. We suggest that species richness variation is mainly conditioned by the failure of many species to go beyond determined temperature range limits.     

Prediction of Transgene integration by Noninvasive Bioluminescent Screening of Microinjected Bovine Embryos

Transgenesis in domestic species, as a research tool and in biotechnological applications, has been limited by the expense of producing transgenic offspring by standard microinjection techniques. A major factor is the inefficiency of maintaining large numbers of recipient females, when a high percentage of these carry nontransgenic fetuses. There are two approaches to reduce this cost, the fusion of transfected fetal fibroblasts with enucleated oocytes, and the screening of microinjected embryos for transgene integration in blastocysts, prior to transfer. Here, we develop a luminescent screening system to select transgenic bovine embryos. A transgene with scaffold attachment regions flanking the murine HSP70.1 promoter linked to firefly luciferase cDNA, was microinjected into pronuclei of in vitro produced zygotes. At the blastocyst stage, the transgene was induced by heat shock (45 °C, 15 min) and 4–6 h later, luciferase expression was analyzed by photon counting imaging. Screened blastocysts were transferred to recipients and day 50 fetuses or calves were analyzed by PCR and Southern blot for transgene integration. When nonluminescent blastocysts were transferred, transgene integration was never observed. Of 13 fetuses derived from luminescent blastocysts, 3 contained integrated transgenes that were functional in all tissues examined. Image analysis of the signal emitted by positive blastocysts revealed that 9 nontransgenic fetuses were obtained from blastocysts that exhibited a localized luminescent signal. On the other hand, 3 of 4 fetuses derived from blastocysts that emitted light over more than 70% of their surface were transgenic. Thus, by selecting luminescent blastocysts on the basis of both signal intensity and distribution, the number of recipient females required to produce transgenic offspring can be greatly reduced. Using this technique it should also be possible to improve the efficiency of transgenesis by microinjection through studies in which vector design and integration conditions are examined at the blastocyst stage.     

Molecular properties of yeast glucokinase

Summary Glucokinase from baker's yeast has been purified to homogeneity. The molecular weight of the subunit is 51,000. The native enzyme sediments with s_20,w values in the range of 19 to nearly 4 S. The presence of glucose and phosphate favors the heavier species while ATP causes depolymerization. Titration experiments with the Ellman reagent support this view.The enzyme subunit has four sulfhydryl residues of which one is more reactive than the other three. However, it does not seem to be directly responsible for the catalytic activity. The amino acid composition of the enzyme is similar to those of the hexokinases P1 and P2 but for aspartic acid and histidine.     

Transposition of the piggyBac element in embryos of Drosophila melanogaster, Aedes aegypti and Trichoplusia ni.

The Lepidopteran transposable element piggyBac is being recognized as a useful vector for genetic engineering in a variety of insect species. This transposon can mediate transformation in the Dipteran species Ceratitis capitata, and can potentially serve as a versatile vector for transformation of a wide variety of insect species. Using a plasmid-based interplasmid transposition assay, we have demonstrated that this transposon, of the short inverted terminal repeat type, is capable of transposition in embryos of three different insect species, Drosophila melanogaster, the yellow fever mosquito Aedes aegypti, and its host of origin, Trichoplusia ni. This assay can confirm the potential utility of piggyBac as a gene transfer tool in a given insect species, and provides an experimental model for assessing molecular mechanisms of transposon movement. Received: 19 November 1998 / Accepted: 1 March 1999