Efficacy of doramectin against experimental infections by some nematode parasites in cattle in New Zealand

A study was undertaken to determine the efficacy of the novel avermectin, doramectin, against experimental larval and adult infections of three species of nematode parasite important to cattle production in New Zealand. Eighteen worm-free dairy bull beef calves were randomly allocated on live weight to three similar treatment groups. Each calf was given 30,000 Ostertagia ostertagi, 20,000 Cooperia spp. and 10,000 Trichostrongylus axei infective larvae as a single dose. One group was treated with doramectin 6 days after infection while the remaining groups received saline or doramectin 27 days after infection. Given as a single subcutaneous injection behind the ear, doramectin at 200 microg/kg removed 99.9-100% of adult and larval stages of O. ostertagi, Cooperia spp. and T. axei when compared to infections established in untreated controls (p<0.001). No adverse reactions were observed following treatment in the doramectin-treated animals. No injection site lesions were found by palpation following treatment or by injection site examination at necropsy.     

Observations on hypoglycaemia associated with a hepatoma in a cat

Disorientation, muscle fasciculations and weakness seen in a 12-year-old neutered female domestic shorthaired cat were attributed to hypoglycaemia associated with a large hepatoma. Glucagon tolerance tests on this cat and a healthy cat showed that their plasma glucose concentrations increased and decreased at about the same rate. Plasma insulin concentrations in the healthy cat increased and decreased in parallel with the plasma glucose concentration. In the affected cat, plasma insulin concentrations increased initially but decreased more rapidly. Reflecting these observations, the amended insulin to glucose ratios in the affected cat were much lower than those of the healthy cat, until the 4-hour sample. Serum somatostatin, somatomedin and gastrin concentrations were measured but no conclusions as to pathogenesis of the hypoglycaemia could be made. The alterations in insulin secretion in the affected cat suggested that altered hormonal control of glucose homeostasis may have occurred with this tumour.     

Periodicity and gradients in dispersal ofAlternaria linicola in linseed crops

Conidia ofAlternaria linicola produced on infected linseed crops were mainly dispersed by wind. The numbers of conidia in the air above linseed crops collected by a Burkard spore sampler were greatest between 1200 h and 1300 h, when the relative humidity was lowest. Although numbers of conidia collected decreased with increasing height within and above the crop canopy, air-borneA. linicola conidia were present up to 80 cm above the crop canopy. Conidia ofA. linicola were transported by wind up to at least 40 m downwind from an artificial line inoculum source, but their numbers decreased with increasing distance from the source. In 1991, 1992, and 1993, the dispersal ofA. linicola conidia above linseed crops followed a seasonal periodicity which was influenced by weather conditions and cultural practices. The greatest numbers of conidia were collected during July, August and early September and coincided with periods favourable for sporulation and with an increase in the incidence of the disease in the senescent crop. Air-borneA. linicola conidia produced on point or line inoculum sources (naturally infected linseed stem debris) were responsible for the spread of the disease in linseed crops. In 1992 and 1993, the disease was first detected downwind from the sources, but by the end of the growing seasons, it had spread in all directions and up to 20 m and 60 m from the sources, respectively. Disease gradients were initially steep near the inoculum sources but they became flatter with time due to the secondary spread of the disease.     

Geological rhythms and cometary impacts

Time-series analysis reveals two dominant, stable long-term periodicities approximately equal to 33 +/- 3 and 260 +/- 25 million years in the known series of geological and biological upheavals during the Phanerozoic Eon. Because the cycles of these episodes agree in period and phase with the cycles of impact cratering on Earth, these results suggest that periodic comet impacts strongly influence global tectonism and biological evolution. These two periodicities could arise from interactions of the solar system with interstellar clouds as the solar system moves cyclically through the Galaxy.     

Polychlorinated Dibenzo-p-dioxins and Dibenzofurans in Sediments from Siskiwit Lake, Isle Royale

Polychlorinated dibenzo-p-dioxins and dibenzofurans were found in sediment from Siskiwit Lake on Isle Royale, Lake Superior, a location which can receive only atmospheric inputs. The source of these compounds is the atmospheric transport of dioxins and furans formed by combustion of domestic and chemical waste.     

Scientific communication and national security in 1984

The federal government's concern about maintaining the lead of the United States over the Soviet Union and its allies in militarily critical technology has led it to attempt to control unwanted technology transfer. Its attempts have extended to control of open scientific communication as well as the transfer of physical devices and blueprints. In 1982, the Corson Panel (an independent ad hoc committee) reviewed the evidence on the costs and benefits of controls and suggested guiding principles for government policy. This article examines the major policy developments since the Corson Panel completed its work. The stringency and the reach of government restrictions, either proposed or in force, go considerably beyond the panel's recommendations.