Trace element inhibition of carcinogenesis and angiogenesis

In separate experimental models the effects of selenium, zinc, potassium, and copper on angiogenesis and carcinogenesis are compared. Inhibitory effects of Se as Na₂SeO₃ and of chloride salts of K and Zn, but not of Cu, on vascularization induced by amelanotic tumor implants (A Mel-4B32) in the Syrian hamster cheek pouch membrane are reported. In an earlier study the induction of new vasculature, angiogenesis, in control chambers implanted with A Mel-4B32 was initially observed on day 4 after implant. Addition of 5, 10, and 50 μg Se at the time of tumor implant delayed the initial capillary proliferation to days 7, 9, 10, respectively (Cancer Lett. 9, 353, 1980). Similarly, in this report addition of 50 μg Zn or 50 μg K delayed angiogenesis to days 7.and 6, respectively. By contrast, addition of 50 μg Cu caused severe inflammation and necrosis of the membrane before capillary proliferation could be observed and the animals had to be sacrificed. In an earlier study we reported the colon tumor incidence in 1,2-dimethylhydrazine (20 mg DMG/kg body weight for 20 weeks) -treated Sprague Dawley rats was reduced from 87 to 40% by a 4 ppm Se (as Na₂SeO₃) supplement in the drinking water (Cancer Lett. 2, 133, 1977). In this study rats were treated with the same dose of carcinogen, but were sacrificed 14 weeks following the last DMH injection. Drinking water supplements with 0.02% Zn (as ZnCl₂), 0.5% K (as KCl), or 0.01% Cu (as CuCl₂) were provided concurrently with the carcinogen and were continued until death or sacrifice. The colon tumor incidence was 18/20 in the DMH control and was reduced to 16/20 by supplemental Zn, reduced to 12/20 by supplemental K, and was unchanged (18/20) by Cu. The tumor incidences in the small intestine and Zymbal gland were all reduced by Zn, K, and Cu supplements compared with the DMH control. The hamster cheek pouch technique may provide a prescreen for potential inhibitors of chemical carcinogenesis in other experimental models.     

THE ULTRASTRUCTURE OF LICHENS. II. CLADONIA CRISTATELLA: THE LICHEN AND ITS ISOLATED SYMBIONTS1,2,3

A Comparative Study Was Made Of The Fine Structure of Cladonia Cristatella and its algal Symbiont Trebouxia Erici in their lichenized and cultured ( nonlichenized) states. Pyrenoglobuli were produced by the alga in the symbiotic and free conditions. Starch was formed during hydrated conditions. Pyrenoglobbuli migrated to the outer parts of the pyrenoid only during dry periods. Dictyosomes and eyespots were observed for the first time in Trebouxia. The pyrenoid divided by fragmentation. Ellipsoidal bodies were common in the hyphae of the lichenized fungus and absent in cultured hyphae, except for 1 colony which had been induced to form pycnidia. The ellipsoidal bodies were associated closely with the internal membrane system of the mycobiont. Haustoria seemed to penetrate the algal cells by enzymatic digestion. Intrahyphal hyphae were common.     

Aflatoxin production by a potent Aspergillus flavus link isolate

An aflatoxin-producing isolate of Aspergillus flavus was found to be a consistent producer of aflatoxin on all substrates which supported the growth of the mold. In competition with six other selected molds, this isolate was dominant except with one species of Penicillium. Aflatoxin production was parallel to the extent of A. flavus growth whether effected by substrate or competition.     

Effects of muscle glycogen and plasma FFA availability on human metabolic responses in cold water.

The purpose of this study was to investigate whether simultaneous alterations in the availability of plasma free fatty acids and muscle glycogen would impair the maintenance of thermal balance during cold water immersion in humans. Eight seminude subjects were immersed on two occasions in 18 degrees C water for 90 min or until rectal temperature (Tre) decreased to 35.5 degrees C. Each immersion followed 2.5 days of a specific dietary and exercise regimen designed to elicit low (LOW) or high glycogen levels (HIGH) in large skeletal muscle groups. Nicotinic acid (1.6 mg/kg) was administered for 2 h before and during immersion to inhibit white adipose tissue lipolysis. Biopsies from the vastus lateralis showed that the glycogen concentration before the immersion was significantly lower in LOW than in HIGH (223 +/- 19 vs. 473 +/- 24 mmol glucose units/kg dry muscle). However, the mean rates of glycogen utilization were not significantly different between trials (LOW 0.62 +/- 0.14 vs. HIGH 0.88 +/- 0.15 mmol glucose units.kg-1.min-1). Nicotinic acid dramatically reduced plasma free fatty acid levels in both trials, averaging 127 +/- 21 mumol/l immediately before the immersion. Cold water immersion did not significantly alter those levels. Plasma glucose levels were significantly reduced after cold water immersion to a similar extent in both trials (18 +/- 4%). Mean respiratory exchange ratio at rest and during immersion was greater in HIGH than LOW, whereas there were no intertrial differences in O2 uptake. The calculated average metabolic heat production during immersion tended to be lower (P = 0.054) in LOW than in HIGH (15.3 +/- 1.9 vs. 17.5 +/- 1.9 kJ/min).(ABSTRACT TRUNCATED AT 250 WORDS)     

Hybrid genes in the analysis of transformation conditions: II. Transient expression vs stable transformation—analysis of parameters influencing gene expression levels and transformation efficiency

Reports on direct gene transfer have dealt with either the obtention of stable transformants and transgenic plants, or described the use of reporter genes to analyse different aspects of gene expression in plant protoplasts and conditions for their use in transient gene expression assays.
In this paper we present comparisons between several transformation techniques, show species-specific differences in efficiencies of stable transformants and in the levels of transient gene expression, and report on the identification of major parameters responsible for DNA uptake as judged from transient chloramphenicol acetyl transferase (CAT) expression levels and from efficiencies of transformation based on kanamycin-resistance. The described procedures have been simplified, optimized and standardized and should allow routine use with a great variety of plant species.     

Expression of different isoenzymes of adenylate deaminase in cultured human muscle cells. Relation to myoadenylate deaminase deficiency.

Adenylate deaminase activity was determined in cultured muscle cells of different maturation grades and muscle biopsies from normal subjects and four patients with a primary myoadenylate deaminase (MAD) deficiency. Adenylate deaminase activity was much lower in cultured human muscle cells than in normal muscle. The activity increased with maturation. The ratio of activities measured at 5 and 2 mM AMP decreased in the order: immature muscle cells greater than more mature muscle cells greater than muscle. Adenylate deaminase activity was detectable in muscle cell cultures of MAD-deficient patients. However, both at 2 and 5 mM AMP this activity was significantly lower than in cultured cells with the same high maturation grade obtained from control subjects, whereas the ratio between the activities at 5 and 2 mM AMP was higher. The observations indicate that transition from a fetal to an adult muscle isoenzyme of adenylate deaminase takes place in human cultured muscle cells during maturation. In cultures obtained from MAD-deficient patients this transition does not occur and only the fetal isoenzyme is present.