Behaviour of rats exposed to trichloroethylene vapour

Rats were exposed to trichloroethylene (TCE) vapour for about five five-day weeks at concentrations from 100 to 1 000 ppm, and at 100 ppm for 12 1/2 weeks. The social behaviour of paired male rats was observed periodically in the home cage for five minutes after they had been exposed to TCE. The principal finding was a consistent reduction of up to 24% in the total acitivity. A single day's exposure to TCE was sufficient at the highest concentration. At 100 ppm, a similar decline in activity was significant after 1 1/2 weeks' exposure in one experiment and 8 1/2 weeks' in another. The decline in activity was fairly uniform and not usually because of specific reductions in particular kinds of behaviour. However, exploration of the cage and submission to, or escape from, the other rat were sometimes specifically reduced. In an 'exploration-thirst' test, rats were deprived of water overnight and placed on two or three occasions in a previously unfamiliar cage. Rats exposed to 100, 200, or 1 000 ppm TCE found water and began drinking sooner than their controls without altering the rate of movement about the cage. These results suggest lowered performance in a familiar situation where rats are usually very active and some loss of inhibitory control in an unfamiliar one. At the present threshold limit value, repeated exposure to TCE eventually had effects similar to those of one day's exposure to a higher concentration, but only after a widely variable delay.

Calcified intraluminal meconium in newborn males with imperforate anus. Enterolithiasis in the newborn

Five cases are reported and reference is made to 3 previous similar cases of calcified intraluminal meconium in newborn males with "imperforate anus." A rectourinary fistula was found in most of the patients; none of the cases had meconium peritonitis. The calcifications may develop in areas of prolonged stasis; the possible added role of the mixture of urine and meconium in utero is raised.

Adenine arabinoside in the management of herpetic keratitis

Ara-A is an effective antiviral agent in the treatment of herpetic ulceration. Its use leads to a quick and high cure rate, and clinical resistance is low. It can successfully be used in cases showing complications after treatment with other antiviral agents.

C3 receptors on direct plaque-forming cells

Using a rosette technique it is shown that only a small proportion of direct plaque-forming cells posses detectable C3 receptors 5 and 7 days after antigenic stimulation. The significance of this result is discussed.

Clostridium botulinum in Scottish fish farms and farmed trout

Rainbow trout and specimens of pond mud were collected from three fish farms and examined for the presence of Clostridium botulinum. Two of the farms were constructed with concrete channels and one was mud-bottomed. Cl. botulinum was isolated only from the mud-bottomed farm (24% of muds), and the isolates were all non-proteolytic type B. The implications of the presence of Cl. botulinum spores in the mud of fish farms is discussed.

Antigen-specific T-cell factor in cell cooperation: physical properties and mapping in the left-hand (K) half of H-2

Mouse thymus cells, educated to poly(tyrosyl,glutamyl)-polyDLalanyl--polylysyl [(T,G)-A--L], release an antigen-specific factor on brief culture in vitro. The factor cooperates with bone marrow cells in the antibody response to (T,G)-A--L in irradiated recipients. Its mol wt determined from Sephadex G100 chromatography is in the region of 50,000. The factor is removed by specific antigen-coated columns, but not by anti-immunoglobulin (anti-Fab, anti-micro, anti-Fv) adsorbents. The factor is removed by alloantisera directed against the H-2 haplotype of the strain in which it is produced. Moreover, only antisera with specificity for the K side of H-2 were successful in removing the factor activity.

Size and base composition of RNA in supercoiled plasmid DNA

The average size and base composition of the covalently integrated RNA segment in supercoiled ColE(1) DNA synthesized in Escherichia coli in the presence of chloramphenicol (CM-ColE(1) DNA) have been determined by two independent methods. The two approaches yielded similar results, indicating that the RNA segment in CM-ColE(1) DNA contains GMP at the 5' end and comprises on the average 25 to 26 ribonucleotides with a base composition of 10-11 G, 3 A, 5-6 C, and 6-7 U.

A stable haemagglutinating antigen for detecting toxoplasma antibodies

The production of a toxoplasma-sensitized cell preparation stable for at least one year at 5 degrees C and its performance in the diagnosis of toxoplasmosis is described.