Corneal vascularization in the Florida manatee (Trichechus manatus latirostris) and three-dimensional reconstruction of vessels

The cornea of the Florida manatee is unique and unusual in its anatomy in that blood vessels have been found throughout. In all other animal species, this is considered a pathological condition impeding vision, and is usually caused by injury or trauma. The purpose of this study was to more clearly describe corneal vascularization by examining the architecture through three-dimensional reconstruction in order to find possible patterns in size, distribution, and location of blood vessels relative to gender, age, location, and season. Twenty-six eyes from 22 individuals were prepared for histologic examination and subsequent three-dimensional reconstruction. Every specimen examined had blood vessels in the cornea, comprising an average of 0.3% of total surface density (volume) of the cornea. No differences were found between individuals based on gender, age, and season. Environmental influences were not a significant factor either, which was not originally anticipated. The presence of vessels at the level of the anterior epithelium was surprising and it appeared that the vascularization was directed more anteriorly than was originally thought. The presence of blood vessels in a prenatal eye was also found. In all the eyes examined, no signs of injury or trauma could be observed. The presence of blood vessels appears to minimally impair vision based on their low density, size, and location. The association of vessels with the anterior epithelium and development of vessels within the fetus point to an evolutionary adaptation possibly due to the manatee's unique ability to move between water bodies.     

Evaluation of PCR systems for the identification and differentiation of Mycoplasma agalactiae and Mycoplasma bovis: a collaborative trial

Diagnostic differentiation between the ruminant pathogens Mycoplasma agalactiae and Mycoplasma bovis is known to be problematic when only conventional serological and biochemical tests are used. The main reason for this is that both agents share a considerable number of related proteins and common epitopes. DNA-based detection methods offer advantages in terms of specificity and sensitivity. However, there is an urgent need to compare currently used PCR assays because they target different genomic regions and, therefore, may perform differently. In the present work, five laboratories, which use PCR routinely, evaluated the specificity of four different PCR systems for M. agalactiae and three systems for M. bovis on a total of 41 strains of the two Mycoplasma species including six previously unidentified strains. As the vast majority of PCR examinations (97.1% of all tests) correctly identified the strains the specificity of all seven detection systems appears to be high. In four cases, incorrect identification by conventional diagnostic methods was rectified by PCR. Isolates from non-typical hosts, i.e. three M. bovis strains from small ruminants and two M. agalactiae strains from cattle, were characterised by sequencing the 16S and part of the 23S ribosomal RNA genes.     

The Relationship between Environmental Amenities and Changing Human Settlement Patterns between 1980 and 2000 in the Midwestern USA

Natural resource amenities may be an attractor as people decide where they will live and invest in property. In the American Midwest these amenities range from lakes to forests to pastoral landscapes, depending on the ecological province. We used simple linear regression models to test the hypotheses that physiographic, land cover (composition and spatial pattern), forest characteristics, land use on undeveloped land, public ownership, soil productivity and proximity to urban centers predict changes in population, housing, and seasonal housing densities over a 10-year interval (1980–1990). We then generated multiple-regression models to predict population, total and seasonal housing density change in the most recent decade (1990–2000) based on ownership and ecological conditions in 1990 and tested them by comparing the predictions to actual change measured by the US Census Bureau. Our results indicate that the independent variables explained between 25 and 40% of the variability in population density change, 42–67% of the variability of total housing density change, and 13–32% of the variability in seasonal housing density change in the 1980s, depending on the province. The strength of the relationships between independent and dependent variables varied by province, and in some cases the sign varied as well. Topographic relief was significantly related to population growth in all provinces, and land cover composition and the presence of water was significantly related to total housing growth in all provinces. There was a surprisingly limited association of any of the independent variables to seasonal housing growth in the northern province, which is commonly perceived to attract seasonal use because of ecological amenities. Proximity to urban centers is related to population and housing density change, but not seasonal housing density change. Our tests indicated that models for population density change showed some utility, but the models for total and seasonal housing density generally performed poorly. Ecologic variables were consistently poor at predicting seasonal housing density change. Our results show that environmental characteristics appear to have some influence on the spatial distribution of population and housing change in the Midwest, although other factors that were not modeled are clearly dominant.     

A trial of biosecurity as a means to control Campylobacter infection of broiler chickens

We ran a controlled intervention trial to assess whether the risk of a broiler flock becoming infected with Campylobacter could be reduced by biosecurity measures. These were a standard method of cleansing and disinfecting the poultry house prior to stocking, and a standard hygiene protocol followed by all personnel who entered the study house during the flock's life. Thirty-nine flocks were allocated to intervention or control groups in a ratio of 1:2. Intervention flocks were asked to follow the specified biosecurity measures; all flocks were monitored weekly for Campylobacter infection. Analysis of infection at 42 days of age and over the life of the flock showed that the risk of thermophilic Campylobacter infection of broilers was reduced by over 50% in intervention flocks. Parts of the intervention identified as significant in the univariable analysis included twice weekly replenishment of boot dip disinfectant; potential independent risk factors identified included the location of ventilation fans and daily sanitisation of the water supply. The non-random allocation of 10 flocks to the control group may have introduced some study bias (the effect of which is discussed in the paper).     

Prevalence of low automated platelet counts in cats: comparison with prevalence of thrombocytopenia based on blood smear estimation

Abstract: True thrombocytopenia is uncommon in cats; however, low platelet counts frequently are found using automated cell counters. Although this discrepancy is a well known problem, the prevalence of low automated platelet counts in feline blood samples has not been documented. We retrospectively compared the prevalence of low automated platelet counts with low blood smear-estimated platelet counts in feline blood samples. Results of blood sample analysis from 359 cats during a 1-year period at the University of Glasgow Veterinary Haematology Laboratory were examined. Smear estimates of platelet number were done in those cases in which records did not indicate adequate platelet numbers. Platelet counts obtained with an impedance counter (Minos Vet, Abx Hematologie) were <200×10⁹ cells/L in 256 samples (71%) and <50×10⁹ cells/L in 43 samples (12%). However, based on estimation of platelet numbers from blood smears, only 11 samples (3.1%) had platelet counts of <200×10⁹ cells/L and 9 samples (2.5%) had counts of <50×10⁹ cells/L. Four cats with thrombocytopenia estimated by blood smear evaluation had clinical signs of a bleeding disorder. Disorders associated with thrombocytopenia included neoplasia, cytotoxic chemotherapy, and infectious diseases. There was no evidence that delay due to mailing of samples was associated with lower automated platelet counts than would have been obtained on the day of sampling. The high prevalence of apparent thrombocytopenia in automated platelet counts was attributed to a combination of platelet aggregation and the impedance method of cell differentiation by size. Vigilance and careful examination of blood smears is required to identify the few cats with true thrombocytopenia.