Propranolol concentrations in plasma after insertion into the vagina.

Six healthy women participated in a study of the concentrations of propranolol achieved in plasma after insertion of the drug into the vagina. In four of the women the concentrations were also determined after administration by mouth. The area under the concentration curve for propranolol administered per vaginam was significantly greater than that after oral administration. There were small significant reduction in systolic blood pressure, pulse rate, and forced expiratory volume in one second after vaginal administration but these did not cause any symptomatic side effects. The tolerability of the vagina to drugs and the safety of this form of treatment remain to be determined. Probably further studies of the contraceptive effects of propranolol should be conducted with the dextro isomer of the drug.     

Human Leprosy in Normal Mice

It has now been shown that normal mice can be used as models for studying the early stages in the development of leprosy. Inoculation into the foot pads of mice of as few as 10⁴ leprosy bacilli leads to infections which spread to distant sites via the blood stream and after two or more years give rise to granulomata and neural damage at the sites of inoculation. Where the tissue response had fully developed it reproduced exactly the histological features of human leprosy in the borderline range.     

Trophic structure and energy flow in a Texas pond

Annual energy flow and mean annual biocontent of eighteen compartments were determined for a 1.0 ha north central Texas pond ecosystem. Annual primary production was 7,789 kcal m^–2 yr^–1, and community production-to-respiration ratio was 1.49. One-third of annual primary production accumulated on the substrate as silt and sedimentation. Biocontents of four trophic levels in the pond were all of the same order of magnitude, averaging 50 kcal m^–2. Wind and water-borne organic material for primary consumers and terrestrial insects for tertiary consumers were substantial allochthonous energy imports into the pond system.     

A field trial with the molluscicide Frescon* for control of Lymnaea peregra Müller,snail host of Diplostomum spathaceum (Rudolphi)

Larval stages of the parasite Diplostomum spathaceum cause blindness in rainbow trout Salmo gairdneri (Richardson.) The adult parasite is found in the intestine of various species of gulls, and larval stages are found in various species of snails belonging to the genus Lymnaea. A field trial was carried out at Lodge Reservoir, near Chelsmford, Essex to test the effectiveness of chemical control of the snail Lymnaea peregra. The molluscicide, Frescon, was applied in the first instance to the whole of the reservoir to give a concentration of 0.025 p.p.m. in the water using a motorized applicator mounted at the rear of a small boat. A second treatment was carried out when only the periphery of the lake was sprayed to a distance of 5 m from the banks to give a concentration of 0-1 p.p.m. No L. peregra were found in samples taken 10 days after the second application of Frescon and it is concluded that this snail had been virtually eliminated from the reservoir. No mortality of trout was observed. Some of the sticklebacks Gasterosteus aculeatus L. were killed and this may be attributable to uneven distribution of molluscicide near the margin of the reservoir. There were no apparent side-effects on aquatic invertebrates or other wild life. Five months after treatment some re-population of the shoreline by L. peregra was observed, and applications of Frescon may therefore need to be repeated on several occasions during the season to maintain an effective level of control. However, where snail pests are confined mainly to the margin of such bodies of water, peripheral treatment may be effective and would be relatively inexpensive.