ULTRASONOGRAPHIC FEATURES OF DIFFUSE HEPATOCELLULAR DISORDERS IN DAIRY CATTLE

Ultrasonography of the liver was performed in 200 Holstein-Friesian dairy cattle using a 3.5 MHz transducer with a linear array electronic scanner. Liver samples were taken, processed and examined microscopically and the fat occupying rate was calculated. The hepatic ultrasonograms were evaluated according to the presence of bright pattern, dark pattern, deep attenuation, vascular blurring and blurring of edges. Of the 200 animals, 96 had a normal liver, 63 had hydropic degeneration of the liver, 37 had fatty infiltration of the liver, 3 had liver dystrophy and I had hepatic amyloidosis, diagnosed through histopathological examination. Amyloidosis was characterized by bright pattern and blurring of edges. Liver dystrophy had higher percentages of bright pattern and blurring of edges than normal liver. Hydropic degeneration had higher percentages of dark pattern and blurring of edges than normal liver. Fatty infiltration had higher percentages of bright pattern, deep attenuation, vascular blurring and blurring of edges than normal liver. The present results suggest that different ultrasonographic patterns can be observed in various diffuse hepatocellular disorders in dairy cattle     

AN OESOPHAGEAL DIVERTICULUM IN A DOG

An 11-month-old male Miniature Poodle was found to regurgitate small volumes of fluid and food particles due to a diverticulum in the thoracic oesophagus. The diverticulum was removed surgically. Histologically the wall contained extensive scar tissue. Longterm recovery was uneventful and 5 months after surgery the dog is in good health     

Bound xenobiotic residues in food commodities of plant and animal origin

The following are extended summaries of Technical Reports which are produced at intervals by the International Union of Pure and Applied Chemistry (IUPAC). They are entirely the responsibility of IUPAC/the authors and do not necessarily reflect the views of the Editorial Board of Pest Management Science. Copyright © 2002 Society of Chemical Industry     

Sand colic in a mule: A case report

A 25-year-old mule was showing signs of colic. Clinical examination revealed acute pain, bilateral abdominal distention, stretching out and standing in this position. Rectal palpation revealed a hardened mass in the ventral region of the pelvic inlet. Surgical intervention was accomplished and faecaliths removed by colotomy. The mule died unexpectedly and postmortem examination revealed sand masses within the right ventral and right dorsal colon which caused obstruction of the intestinal tract in sternal and diaphragmatic flexures, respectively. This appears to be the first report of sand colic in a mule in Iran.     

Methods of assessing extinction risk in marine fishes

The decline and disappearance of species from large parts of their former geographical range has become an important issue in fisheries ecology. There is a need to identify which species are at risk of extinction. The available approaches have been subject to considerable debate – particularly when applied to commercially exploited species. Here we have compiled methods that have been used or may be used for assessing threat status of marine organisms. We organize the methods according to the availability of data on the natural history, ecology and population biology of species. There are three general approaches to inferring or assessing extinction risk: (i) correlative approaches based on knowledge of life histories and ecology; (ii) time‐series approaches that examine changes in abundance; and (iii) demographic approaches based on age‐ or stage‐based schedules of vital rates and fisheries reference points. Many methods are well suited to species that are highly catchable and/or have relatively low productivity, but theory is less well developed for assessing extinction risk in species exhibiting narrow geographical distributions or ecological specialization. There is considerable variation in both definitions of extinction risk and the precision and defensibility of the available risk assessment methods, so we suggest a two‐tiered approach for defining and assessing extinction risk. First, simple methods requiring a few easily estimated parameters are used to triage or rapidly assess large numbers of populations and species to identify potentially vulnerable populations or species. Second, the populations and species identified as vulnerable by this process can then be subject to more detailed and rigorous population analysis explicitly considering sources of error and uncertainty.     

Temperature effects on the action of acylurea insecticides against tobacco hornworm (Manduca sexta) larvae

The toxic effects of six acylurea insecticides on larvae of the tobacco hornworm were investigated at each of four environmental temperatures (20, 25, 30 and 35°C). This spans the range of temperatures which the insects can tolerate. For all the acylureas tested, mortality increased with temperature when either newly hatched or fourth-instar larvae were given insecticide in their food. Sub-lethal growth inhibition also became more pronounced at progressively higher environmental temperatures. This temperature dependence of acylurea action was not due to altered uptake of the insecticide, since there was no significant variation with temperature in the amount of [¹⁴C]flufenoxuron taken up by fifth-instar larvae when given a single meal containing labelled insecticide. Additionally, mortality of fourth-instar larvae given a single intra-haemocoelic injection of flufenoxuron was significantly greater at higher temperatures, implying that temperature affects a process that occurs after insecticide uptake. The intrinsic ability of acylureas to inhibit chitin synthesis is temperaturesensitive, since flufenoxuron inhibited the incorporation of [¹⁴C]N-acetylalucosamine into chitin by proleg epidermis in vitro significantly less well at 20°C than at the higher temperatures tested. However, there was no significant variation between the effectiveness of in-vitro chitin synthesis inhibition at 25, 30 and 35°C. These data show that the effectiveness of acylurea insecticides is subject to strong temperature effects in the range of temperatures likely to be experienced in the field.     

The cuticle,growth and moulting in insects: The essential background to the action of acylurea insecticides

The functions, structure and biochemistry of the insect cuticle in relation to the moulting cycle are briefly reviewed as an introduction to the actions of insecticides that act on the cuticle, particularly acylureas. The symptoms of poisoning with diflubenzuron (DFB) and other acylureas are consistent with ultra-structural and biochemical evidence that these insecticides inhibit the formation of chitin microfibrils in newly synthesised cuticle. It is probable that DFB acts at a late stage in chitin biosynthesis, perhaps inhibiting chitin synthase (CS) itself. However, the results of studies using cell-free preparations of CS have not, on the whole, supported this hypothesis. A number of alternative suggestions as to the mode of action of DFB are reviewed. Among the most attractive of these is the possibility that DFB may inhibit the transmembrane transport of chitin synthesis precursors from their site of production within the epidermal cells to the site of the final poly condensation reaction, presumably at the apical membrane of the epidermal microvilli.