Enhancement of epidermal growth factor receptor expression on glioma cells by recombinant tumor necrosis factor α

Summary Recombinant tumor necrosis factor (rTNF; optimal dose 1000 U/ml) significantly increased the density of epidermal growth factor receptor (EGF-R) in three of four glioma cell lines in culture as determined by binding analysis of anti-EGF-R monoclonal antibody (mAb) 425. Since enhancement of EGF-R expression by rTNF- was inhibited when cells were treated with the protein synthesis inhibitor cycloheximide, the effects of rTNF may be protein-synthesis-dependent. The dose of rTNF that was optimal for up-regulation of EGF-R on glioma cells did not inhibit the growth of these cells.¹²⁵I-labeled mAb 425 lysed glioma cells in culture following its internalization into the cells. After glioma cells had been treated with rTNF, the growth-inhibitory effects of the mAb were significantly enhanced, probably a reflection of the increase in EGF-R density on the tumor cell surfaces. The rTNF effects were specific to the EGF-R and did not affect unrelated glioma-associated antigens. In our previous clinical trials,¹²⁵I-labeled mAb 425 showed immunotherapeutic effects in glioma patients. The present study provides the basis for considerations of combined immunotherapy of glioma patients with¹²⁵I-labeled mAb 425 and rTNF.     

A portable EAG system for the measurement of pheromone concentrations in the field

A robust and portable apparatus for the measurement of pheromoneconcentrations under field conditions has been developed. Ituses the insect antenna (Lobesia botrana Hb.) itself as a sensitiveand specific pheromone detector. Shock-proof contact with theelectrodes is maintained by fixing the antenna in a specially-shapedplexiglass holder mounted within a glass tube. This allows measurementsto be made while moving the apparatus. Continuous airflow throughthe tube is generated by a suction pump and the incoming aircan be purified by passage through a charcoal filter. This allowsto readjust the offset and to calibrate the instrument by theapplication of pheromone pulses of known concentrations. Removalof the filter allows the direct access of ambient air over theantenna which responds by generating an electro-antennogram(EAG) as a measure of the pheromone concentration. Using the calibration curve, relative pheromone concentrationsin ambient air in a vineyard can be determined. Sample measurementsfrom areas treated with artificial pheromone for pest controlare presented.     

Regeneration of transgenic plants of Prunus armeniaca containing the coat protein gene of Plum Pox Virus

Summary A system was developed which allows the transfer of foreign genes into apricot cultivars. We report the transformation and regeneration of Prunus armeniaca plants with Agrobacterium tumefaciens strain LBA 4404 containing various binary plasmids, pBinGUSint, carrying the marker gene ß-glucuronidase (GUS) and pBinPPVm, carrying the coat protein gene of Plum Pox Virus (PPV). The marker gene GUS was used for optical evaluation of the efficiency of the transformation system. The coat protein gene of PPV was used to introduce coat protein mediated resistance against one of the most important pathogens of stone fruit trees in Europe and the whole Mediterranean area. This is the first report of the successful integration of a viral coat protein gene into a fruit tree species, opening a new perspective on the control of the disease.Abbreviations GUS ß-glucuronidase - PPV Plum Pox Virus - BA 6-benzylaminopurine - NPTII neomycin phosphotransferase II - CP coat protein - CaMV Cauliflower Mosaic Virus - P35S 35S promoter - MS Murashige and Skoog - PCR polymerase chain reaction - P/C/I phenol/chloroform/isoamylalcohol - RNase ribonuclease - dNTP deoxyribonucleosidetriphosphate - DMSO dimethyl sulfoxide     

Mode of action studies on a Manduca sexta diuretic hormone

The mode of action of a diuretic hormone from pharate adult Manduca Sexta heads, which triggers fluid loss in M. sexta larvae and Pieris rapae adults, was studied. In vivo, Mas-DH (M. sexta diuretic hormone) decreased fluid absorption from larval recta, and increased levels of the second messenger cAMP in recta and Malpighian tubules (Mt) from larvae, and in fat body of larvae and adult M. sexta. In vitro, Mas-DH triggered minor changes in fluid loss from adult Mt, but did not affect levels of cAMP in Mt from larvae, pharate adults, or adults, though it elevated cAMP levels in fat body of these stages. © 1992 Wiley-Liss, Inc.     

Calcium transport and compartment analysis of free and exchangeable calcium in Plasmodium falciparum-infected red blood cells.

Calcium (Ca2+) is indispensable for normal development of the various stages of the asexual erythrocytic cycle of malaria parasites. However, the mechanisms involved in Ca2+ uptake, compartmentalization and cellular regulation are poorly understood. To clarify some of these issues, we have measured total, exchangeable, and free Ca2+ in normal red cells (RBCs) and Plasmodium falciparum (FCR-3)-infected cells (IRBCs) as a function of parasite development. All three forms of Ca2+ were found to be substantially higher in IRBCs than in RBCs, and to increase with parasite maturation up to the trophozoite stage and decline thereafter. Exchangeable and free [Ca2+] in host cell and parasite compartments were determined by selectively lysing IRBCs with Sendai virus, and estimating these parameters in the lysate (host cytosol) and the pellet (parasite cytosol). Levels of both exchangeable and free [Ca2+] were found to be higher in host cytosol than in parasite cytosol. The Ca2+ gradient across the parasite membrane can be maintained by the pH gradient across this membrane by means of a Ca2+/H+ antiporter. Host cytosol free [Ca2+] reached levels known to produce structural, physiological and biochemical changes in RBCs, and could account for similar features normally seen in malaria-infected red cells. Uptake of Ca2+ into IRBCs was nonsaturable and substantially faster than the saturable Ca2+ uptake into RBCs. The rate of Ca2+ uptake across the parasite membrane was even faster suggesting that the rate-limiting step in uptake into intact IRBCs is the translocation of Ca2+ across the host cell membrane.     

Proton and sucrose transport in isolated tonoplast vesicles from sugarcane stalk tissue

Tonoplast vesicles prepared from immature sugarcane ( Saccharum spp., hybrid cv. H65–7052) tissue and purified on a discontinuous dextran gradient take up sucrose. Uptake was stimulated by MgATP. Evidence that the mechanism is linked to proton transport is derived from "pH jump'data and from inhibition of ATP-stimulated sucrose transport by the protonophore carbonyl cyanide m -chlorophenylhydrazone (CCCP) and by the proton-channel blocker of proton-linked ATPases. N. N '-dicyclo-hexylcarbodiimide (DCCD). A saturable phase of sucrose uptake was found at low substrate concentrations, and a linear phase characterized uptake at higher concentrations. Uptake was specific for sucrose, as demonstrated by competition experiments with various sugars. Sucrose uptake by the vesicle fraction was inhibited by KNO₃, protonophores and protein modifying reagents, whereas sodium orthovanadate had no effect. Overall, the evidence suggests an ATP-hydrolysis-dependent tonoplasl antiport for sucrose transport, although a more direct influence of ATP on conformational changes in relevant tonoplast proteins cannot be ruled out.