Serotonin uptake in the central nervous system of rats fed a corn-diet

1. Endogenous serotonin (5-HT), 5-hydroxyindol acetic acid (5-HIAA) content and exogenous 5-HT uptake (Km and Vmax) were measured in different brain regions (cerebellum, diencephalon, brain stem and telencephalon) of rats fed with a corn diet and restricted protein (8%) diet during 6 weeks. 2. A reduction of 5-HT levels was found in all regions studied of animals fed a corn diet, whereas, 5-HIAA was only decreased in brain stem and diencephalon. 3. An important increase in Km and Vmax were registered in brain stem and diencephalon of protein restricted animals, whereas, an increase of 5-HT uptake affinity in cerebellum, brain stem and telencephalon (35, 42 and 33% respectively) was observed. Simultaneously, under corn diet conditions, the Vmax decreased 40, 30 and 34% respectively in those regions. 4. It is suggested that the brain stem was the more sensitive area under nutritional restricted conditions and the development of some possible compensatory mechanisms of the 5-HTergic system is discussed.     

Metastatic melanoma to the facial nerve

Isolated metastatic malignant melanoma to the facial nerve has never been reported. This presentation illustrates a primary melanoma of the helix of the ear that was treated by excisional biopsy and then wedge resection in 1983. The primary melanoma was Clark's level IV and 1.3 mm in thickness. In 1985, a facial paresis slowly developed. There was no gross evidence of recurrent melanoma in the ear or neck, but CT scan showed a mass in the region of the stylo mastoid foramen. A reoperation of the primary site revealed metastatic melanoma in the facial nerve, expanding it to approximately 10 times its normal size. A composite resection was done for the melanoma, and the paralyzed face was immediately rehabilitated by a masseter muscle transfer. The patient received 6000 rads to this area postoperatively and has remained free of disease to date, having returned to his profession as a dentist. A detailed study of all the specimens indicated that this represented a primary metastasis to the facial nerve.     

The influence of species frequency,temperature regime and previous development condition on relative competitive ability between Drosophila melanogaster and Drosophila simulans

Some fitness components of Drosophila melanogaster and D. simulans were measured in control and inter-specific competition tests. The effects derived from different relative frequencies of the competitors were examined under a factorial scheme with two temperatures, 21 °C or room temperature, and with adults developed in mixed- or pure-species cultures. D. melanogaster appeared as a strong competitor and outnumbered D. simulans in all the culture conditions. This was because intraspecific competition was stronger than inter-specific competition for D. melanogaster whereas the reverse occurred for D. simulans. In competition, the productivity of both species generally appeared as frequency-dependent, although density-dependent productivity seems to be a more accurate explanation. D. simulans was very sensitive to variations of laboratory conditions. Room temperature and previous development with D. melanogaster were more favorable for D. simulans than 21 °C and previous development in pure cultures. These factors did not substantially affect D. melanogaster, which showed a greater ability of adaptation to laboratory conditions than its sibling D. simulans.     

Short term regulation by lysine of ornithine decarboxylase activity in Dictyostelium discoideum

A transitory increase in ornithine decarboxylase activity has been observed soon after food removal from Dictyostelium discoideum amoeba. This increase can be prevented by supplementation of the differentiation buffer with the 11 amino acids known for their ability to retard the development of this slime mold. Lysine can replace the amino acid mixture with an apparent inhibition constant of 50 micromolar. This inhibition by lysine, which was only observed in vivo, took place within 5 min and was readily reversed upon lysine removal.     

In vitro modification of Candida albicans invasiveness

Candida albicans produces germ-tubes (GT) when it is incubated in animal or human serum. This dimorphism is responsible for its invasive ability.The purpose of the present paper is (1) to evaluate the ability of rat peritoneal macrophages to inhibit GT production of ingested Candida albicans, obtained from immunized rats and then activated in vitro with Candida-induced lymphokines; (2) to determinate any possible alteration of phagocytic and candidacidal activities.The phagocytes were obtained from rats immunized with viable C. albicans. Some of them were exposed to Candida-induced lymphokines in order to activate the macrophages in vitro. The monolayers of activated, immune and normal macrophages were infected with a C. albicans suspension during 4 hr.Activated macrophages presented not only the highest phagocytic and candidacidal activities but a noticeable inhibition of GT formation and incremented candidacidal activity.     

Microbial metabolism of chlorosalicylates: effect of prolonged subcultivation on constructed strains

The hybrid strain Pseudomonas sp. WR4016 was subcultivated with increasing concentrations of 5-chlorosalicylate (510 mM) as sole carbon source over a period of 9 months. At intervals of approximately 3 months derivative strains WR4017, WR4018 and WR4019 were isolated which exhibited higher growth rates and increased substrate tolerance. Comparative analysis of the turnover rates of the key enzymes in chlorosalicylate degradation showed that the adaptation process did not result from structural modifications of these proteins. Instead, balanced over-production of the salicylate hydroxylase and catechol 1,2-dioxygenase prevented the accumulation of toxic chlorocatechols and accounted for the reduction of the doubling times with 4- or 5-chlorosalicylate. A comparative analysis of a genetically engineered chlorosalicylate degrader PL300-1 showed similar regulatory patterns as the most advanced isolate WR4019 from the adaptation series.     

Detection of antigens on nitrocellulose paper immunoblots with monoclonal antibodies

A very sensitive method for the detection of antigen-antibody complexes on nitrocellulose paper immunoblots is described. The protein antigens are separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by their electrophoretic transfer onto a nitrocellulose sheet (“Western blot”). The protein antigens bound to the nitrocellulose paper are exposed to the monoclonal antibody and the antibody-antigen complexes are detected on the paper by an immunoenzymatic reaction. The improved sensitivity of this method is the result of (i) the use of the detergent Tween 20 in blocking the nonspecific binding of the antibodies to the nitrocellulose paper, (ii) the use of a peroxidase-antiperoxidase (PAP) reaction, and (iii) the intensification of the diaminobenzidine reaction product with nickel and cobalt ions in phosphate buffer.