Effects of oral meso-2,3-dimercaptosuccinic acid (DMSA) administration on late gestation and postnatal development in the mouse

The present study was conducted to evaluate the effects of meso-2,3-dimercaptosuccinic acid (DMSA) on late gestation and postnatal viability and growth in the mouse. DMSA was given po to four groups of pregnant Swiss mice at 0, 200, 400, and 800 mg/kg/day from day 14 of pregnancy until postnatal day 21. At birth, the following data were recorded: length of gestation, number of live, dead, and abnormal pups, sex, and individual pup weights. Each pup was weighed again on day 4, 14, and 21 of lactation. Pinna detachment, incisor eruption and eye opening were also monitored. No treatment-related signs of toxicity were noted in any of the dams during the study. No adverse effects on offspring survival or development were evident in the 200 or 400 mg DMSA/kg/day groups. However, on days 14 and 21 of lactation a significant decrease in pup body weight was observed in the 800 mg/kg/day group. Also, a significant increase in the relative weight of the brain was seen in this group. The "no observable effect level" (NOEL) for health hazards to the developing pup was greater than 400 mg/kg/day. This dose is higher than the amounts of DMSA usually given in the treatment of human heavy metal intoxications.     

Dilute passage promotes expression of genetic and phenotypic variants of human immunodeficiency virus type 1 in cell culture.

We have studied the extent of genetic and phenotypic diversification of human immunodeficiency virus type 1 (HIV-1) upon 15 serial passages of clonal viral populations in MT-4 cell cultures. Several genetic and phenotypic modifications previously noted during evolution of HIV-1 in infected humans were also observed upon passages of the virus in cell culture. Notably, the transition from non-syncytium-inducing to syncytium-inducing phenotype (previously observed during disease progression) and fixation of amino acid substitutions at the main antigenic loop V3 of gp120 were observed in the course of replication of the virus in MT-4 cell cultures in the absence of immune selection. Interestingly, most genetic and phenotypic alterations occurred upon passage of the virus at a low multiplicity of infection (0.001 infectious particles per cell) rather than at a higher multiplicity of infection (0.1 infectious particles per cell). The degree of genetic diversification attained by HIV-1, estimated by the RNase A mismatch cleavage method and by nucleotide sequencing, is of about 0.03% of genomic sites mutated after 15 serial passages. This value is not significantly different from previous estimates for foot-and-mouth disease virus when subjected to a similar process and analysis. We conclude that several genetic and phenotypic modifications of HIV-1 previously observed in vivo occur also in the constant environment provided by a cell culture system. Dilute passage promotes in a highly significant way the expression of deviant HIV-1 genomes.     

Toxicology of vanadium compounds in diabetic rats: The action of chelating agents on vanadium accumulation

The possible use of vanadium compounds in the treatment of diabetic patients is now being evaluated. However, previously to establish the optimal maximum dose for diabetes therapy, it should be taken into account that vanadium is a highly toxic element to man and animals. The toxic effects of vanadium are here reviewed. The tissue vanadium accumulation, which would mean an additional risk of toxicity following prolonged vanadium administration is also discussed. Recently, it has been shown that coadministration of vanadate and TIRON, an effective chelator in the treatment of vanadium intoxication, reduced the tissue accumulation of this element, decreasing the possibility of toxic side effects derived from chronic vanadium administration without diminishing the hypoglycemic effect of vanadium. However, previously to assess the effectiveness of this treatment in diabetic patients, a critical reevaluation of the antidiabetic action of vanadium and its potential toxicity is clearly needed.     

Treatment of acute cobalt intoxication in rats with L-methionine

The antidotal action of L-methionine in acute cobalt (II) chloride intoxication given orally or intraperitoneally to rats has been investigated in this paper. The doses of CoCl2 (2.73 mmole/kg oral, 0.21 mmole/kg i.p.) are always above their LD50 for both means of administration, reaching during oral administration values above its LD95 (4.20 mmole/kg). The doses of L-methionine varied from 0.63 mmole/kg (i.p.) to 8.19 mmole/kg (orally). L-methionine did not show a significant antidotal action (mortality rates) against the other sulphurous aminoacid: L-cysteine, which is considered an effective antidote. The administration of Co2+-methionine chelates prepared in vitro, showed rates of 10% mortality when given orally and 30% when given intraperitoneally, against Co2+-cysteine and co2+-N-acetylcysteine chelates with rates of 0% mortality. No significant functional changes were observed in the survivors killed seven days after administration in groups receiving L-methionine. Although L-methionine cannot be considered an effective antidote, it is likely to reduce partially the toxic effects of cobalt.     

Evolution of the nucleotide sequence of influenza virus RNA segment 7 during drift of the H3N2 subtype

The complete genetic information contained in the influenza virus RNA segment 7 of the A/Bangkok/ $\text{1}\text{79}$ (H3N2) strain has been cloned by in vitro synthesis of the complementary dsDNA and its insertion into plasmid pBR322. The nucleotide sequence of the viral RNA segment has been determined from the cDNA insert. It is 1027 nucleotides long, and contains two open reading frames, as shown for other influenza virus strains. When compared with the previously published sequence for the A/Udorn/72 (H3N2) strain, 15 nucleotide exchanges are observed, most of them silent mutations, and only two causing amino acid changes in each of the M1 and M2 protein sequences.     

Heteronarce rierai,a new narkid ray from Mozambique,western Indian ocean

Heteronarce rierai sp. nov. is described on the basis of six specimens, one male and five females, caught in the waters off Mozambique (western Indian Ocean). Total lengths range from 257 to 296 mm. The new species is distinguished from the three other species of the genusHeteronarce by its narrower disc width (29.6% of TL in male, and 33.0 to 39.2% of TL in females), shorter disc length (32.7% of TL in male, and 34.4 to 40.6% of TL in females), and its longer interdorsal distance (10.1 to 11.7% of TL).     

Young Children’s Drawings of Plant Life: A Study Concerning the Use of Colours and its Relationship with Age

This study examines the drawings that elementary grade school children make on the subject of plant life. More specifically, the pictorial elements drawn by children are analysed together with their colour choices and the size of coloured surfaces. Furthermore, the results are put into perspective with the age of the children in the sample. The results indicate that there are significant differences in terms of both the content of the drawings and how colours are used. These findings are linked to the process of the comprehension of the plant world that, according to several studies, initially begins in elementary education. The conclusions highlight the convenience of considering the study of young children’s drawings and colour choices in order to achieve a clearer picture regarding the initial steps of the process of the understanding of biological phenomena in early childhood.