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.     

Rifampicin for lepromatous leprosy: nine years' experience.

Over 100 patients with lepromatous leprosy were treated with rifampicin in a series of pilot, uncontrolled, and controlled trials in 1968-77. The rapid bactericidal effect of rifampicin on Mycobacterium leprae was confirmed. Clinical improvement became apparent sometimes as early as 14 days after the start of treatment. Nevertheless, a few persisting viable M leprae were detected as long as five years after the start of treatment with rifampicin either by itself or in combination with the bacteriostatic drug thiambutosine. Treatment with rifampicin and dapsone for six months reduced the number of persisting leprosy bacteria more than treatment with dapsone alone. Although rifampicin proved more effective than dapsone, it is unlikely that used by itself if can significantly shorten the length of treatment in lepromatous leprosy. Therefore initial intensive combined treatment with two or more bactericidal drugs (including rifampicin) warrants further investigation in both untreated leprosy and lepromatous leprosy resistant to dapsone.     

Impacts and management of wild pigs Sus scrofa in Australia

相似文献   

A high-fat diet suppresses de novo lipogenesis and desaturation but not elongation and triglyceride synthesis in mice

Intracellular lipids and their synthesis contribute to the mechanisms and complications of obesity-associated diseases. We describe an NMR approach that provides an abbreviated lipidomic analysis with concurrent lipid biosynthetic fluxes. Following deuterated water administration, positional isotopomer analysis by deuterium NMR of specific lipid species was used to examine flux through de novo lipogenesis (DNL), FA elongation, desaturation, and TG-glycerol synthesis. The NMR method obviated certain assumptions regarding sites of enrichment and exchangeable hydrogens required by mass isotope methods. The approach was responsive to genetic and pharmacological gain or loss of function of DNL, elongation, desaturation, and glyceride synthesis. BDF1 mice consuming a high-fat diet (HFD) or matched low-fat diet for 35 weeks were examined across feeding periods to determine how flux through these pathways contributes to diet induced fatty liver and obesity. HFD mice had increased rates of FA elongation and glyceride synthesis. However DNL was markedly suppressed despite insulin resistance and obesity. We conclude that most hepatic TGs in the liver of HFD mice were formed from the reesterification of existing or ingested lipids, not DNL.     

Messages Do Diffuse Faster than Messengers: Reconciling Disparate Estimates of the Morphogen Bicoid Diffusion Coefficient

The gradient of Bicoid (Bcd) is key for the establishment of the anterior-posterior axis in Drosophila embryos. The gradient properties are compatible with the SDD model in which Bcd is synthesized at the anterior pole and then diffuses into the embryo and is degraded with a characteristic time. Within this model, the Bcd diffusion coefficient is critical to set the timescale of gradient formation. This coefficient has been measured using two optical techniques, Fluorescence Recovery After Photobleaching (FRAP) and Fluorescence Correlation Spectroscopy (FCS), obtaining estimates in which the FCS value is an order of magnitude larger than the FRAP one. This discrepancy raises the following questions: which estimate is "correct''''; what is the reason for the disparity; and can the SDD model explain Bcd gradient formation within the experimentally observed times? In this paper, we use a simple biophysical model in which Bcd diffuses and interacts with binding sites to show that both the FRAP and the FCS estimates may be correct and compatible with the observed timescale of gradient formation. The discrepancy arises from the fact that FCS and FRAP report on different effective (concentration dependent) diffusion coefficients, one of which describes the spreading rate of the individual Bcd molecules (the messengers) and the other one that of their concentration (the message). The latter is the one that is more relevant for the gradient establishment and is compatible with its formation within the experimentally observed times.