Hydrixyl radical generation by the tetracycline antibiotics with free radical damage to DNA, lipids and carbohydrate in the presence of iron and copper salts

Tetracycline antibiotics caused the degradation of carbohydrate in the presence of a ferric salt at pH 7.4. This degradation appeared to involve hydroxyl radicals since the damage was substantially reduced by the presence of catalase, superoxide dismutase, scavengers of the hydroxyl radical and metal chelators. Similarly, the tetracycline antibiotics in the presence of a ferric salt greatly stimulated the peroxidation of liposomal membranes. This damage, which did not implicate the hydroxyl radical, was significantly reduced by the addition of chain-breaking antioxidants and metal chelators. Only copper salts in the presence of tetracycline antibiotics, however, caused substantial damage to linear duplex DNA. Studies with inhibitors suggested that damage to DNA did involve hydroxyl radicals.     

Gene expression in chemically transformed mouse embryo cells: selective enhancement of the expression of C type RNA tumor virus genes.

Treatment of a nontumorigenic clone of AKR mouse embryo cells in culture with a variety of polycyclic aromatic hydrocarbons has resulted in the development of derivative clones which are highly tumorigenic and exhibit other characteristics of the transformed phenotype. A 3-methylcholanthrene-transformed derivative clone (clone MCA) has been compared to the parent clone (clone 2B) with respect to the abundance and diversity of polysomal poly(A)-containing mRNA sequences. Hybridization kinetic experiments show that the poly(A)-containing sequences of both clones are organized into indistinguishable abundance classes, and that the vast majority of the sequences are common to both the parent and derivative clones. The levels of two specific messenger RNAs (α- and β-globin mRNA) which characterize highly differentiated mouse erythroid cells were much less than 1 molecule per cell in either cell type. Titration of a balanced complementary DNA probe to AKR murine leukemia virus (AKR-MuLV) 70S RNA with purified polysomal poly(A)-containing RNA from both parent and derivative clones shows that approximately 5000 and 1200 viral 35S RNA equivalents are present in the cytoplasm of growing and resting clone MCA cells, respectively. Rapidly growing clone 2B cells contain less than about 30 viral 35S RNA equivalents per cell. Viral specific sequences therefore correspond to members of the high abundance class of poly(A)-containing RNA sequences in clone MCA cells and to the low abundance class of sequences in clone 2B cells. Within the limits of detection, this large increase in abundance is characteristic only of viral specific RNA sequences.     

Cuticular permeability of the black widow spiderLatrodectus hesperus

Summary The water permeability of abdominal cuticle of the black widow spiderLatrodectus hesperus was examined using gravimetric, in situ and in vitro techniques. At 30 °C and 0% RH, water loss rates (WLR) of whole, living spiders were higher than in situ WLR measured with capsules secured to the cuticle surface, while in situ WLR of living spiders were greater than in situ WLR for dead spiders. Although these differences are not statistically significant, these results suggest that there may be important extracuticular water loss pathways in living animals, and that the living epidermis does not provide an active barrier to water efflux. In vitro WLR measured on excised pieces of cuticle, in contrast, were nearly 5 times greater than in situ WLR of dead spiders. Temperature/transpiration curves show that permeability increased exponentially with rising temperature, with rates increasing most rapidly between 45 and 51 °C. The WLR for spiders whose cuticle was scrubbed with chloroform: methanol was consistently and substantially (200x) higher than WLR for control or sham-treated spiders. Discussion focuses on the location and composition of the epicuticular lipid water barrier and the potential use of black widow cuticle for in vitro studies of lipid barrier effectiveness in arthropods in general.     

Design and evaluation of a chronic EMG multichannel detection system for long-term recordings of hindlimb muscles in behaving mice

Mouse models are commonly used for identifying the behavioral consequences of genetic modifications, progression or recovery from disease or trauma models, and understanding spinal circuitry. Electromyographic recordings (EMGs) are recognized as providing information not possible from standard behavioral analyses involving gross behavioral or kinematic assessments. We describe here a method for recording from relatively large numbers of muscles in behaving mice. We demonstrate the use of this approach for recording from hindlimb muscles bilaterally in intact animals, following spinal cord injury, and during the progression of ALS. This design can be used in a variety of applications in order to characterize the coordination strategies of mice in health and disease.     

Bronchiolar Carcinoma: A Report of Six Cases

Bronchiolar carcinoma is a malignant tumour which apparently arises in a terminal bronchiole from which it spreads either by bronchial embolization or by lymphogenous and/or hematogenous dissemination. It is not a common neoplasm.Histologically, the tumour bears a striking resemblance to the disease of sheep, jagziekte, which is of virus etiology. A very common finding in reported cases is preexisting pulmonary fibrosis. At the Nova Scotia Sanatorium, Kentville, 80 cases of primary lung cancer have been encountered within the past 25 years. Six of these were bronchiolar carcinomas. Five patients had co-existing chronic pulmonary disease, bronchiectasis in one and tuberculosis in four. One patient died of a rapidly progressive bilateral lesion and five were explored. Lobectomy was done in all five, but in one for palliation only. Three patients are alive and well three, six and 14 years, respectively, after their operations.