QUANTITATION AND CHARACTERIZATION OF BRAIN TUBULIN (COLCHICINE-BINDING ACTIVITY) IN DEVELOPING HYPOTHYROID RATS

The influence of early hypothyroidism on the concentration and biochemical properties of soluble and particulate tubulin from the cerebral cortex and cerebellum was investigated during development in the rat. Cellular soluble tubulin concentration (pmol colchicine bound/μg DNA) was approx 16% lower in both brain areas of hypothyroid animals compared to controls at 25 days of age. No effect of thyroid hormone deficiency was observed when tubulin concentration was expressed in terms of tissue protein or weight. The particulate tubulin concentration was approx 20% lower in the cerebral cortex of 25-day-old hypothyroid rats although the distribution of tubulin between soluble and particulate fractions was similar to controls. The incorporation of [¹⁴C]leucine into cerebral cortical tubulin in vitro (c.p.m. in tubulin/c.p.m. in total protein) was not significantly altered by the hormonal deficiency. Thus there was no apparent evidence of a selective defect in tubulin synthesis. Tubulin from hypothyroid rats behaved similarly to control samples with respect to the effects of pharmacological agents and temperature, lability of binding, chromatographic profile and electrophoretic mobility on sodium dodecyl sulfate polyacrylamide gels.     

Resolving UV Bioactinometric Results with Intensity and Time Distributions

A UV reactor with an annular design, a total liquid volume of 460[emsp4 ]ml, and outfitted with a single lamp with 1690[emsp4 ]mW of germicidal power was tested. Coliphage MS2 was used as a bioactinometer to measure the UV dose at a flow rate of 56.7[emsp4 ]ml/sec in water with a very low absorbance. The Beers Law coefficient was A₁₀0.003. The measured dose (MS2 bioactinometry) was 35.2±1.1[emsp4 ]mW-sec/cm².A retention time distribution was generated with a dye tracer study. The reactor was modeled as if flow was confined to ten equal volume paths existing as concentric rings around the lamp. The UV intensity along each path (ith intensity) was calculated to generate a simulated distribution of UV intensity in the reactor. The retention time distribution was subdivided to estimate the retention time associated with each decile jth time) of the total flow.Seven methods of associating the ith intensity with the jth retention time were used to produce simulated dose distributions for the reactor. The average UV dose for each distribution was calculated as the average of the products of I and t (AP protocol) and by the apparent survival (AS protocol), in which the predicted survival along each path was averaged to back-calculate dose from the reference batch inactivation curve. The average dose predicted assuming that time and intensity were independent was 51.5[emsp4 ]mW-sec/cm² based on the arithmetic average (AP protocol). Using the apparent survival method, the predicted dose for the independent distribution (I independent of t) was 36.4[emsp4 ]mW-sec/cm². Three methods of developing dependent structure between time and intensity were tested. In the best possible case for stratified flow (I negatively correlated with t) the calculated (AS) intensity was 46.3[emsp4 ]mW-sec/cm^2. In the worst case for stratified flow (I positively correlated with t) the AS intensity was 32.0[emsp4 ]mW-sec/cm². In a rational case where flows were assumed to be distributed parabolically (low flow at the wall and at the lamp) produced an AS intensity of 37.7[emsp4 ]mW-sec/cm². When either time or intensity was averaged, while the other variable was allowed to keep its distribution, the (AS) dose (time averaged 43.3[emsp4 ]mW-sec/cm², intensity averaged 41.0[emsp4 ]mW-sec/cm²), yielded a poor prediction compared to the measured value.The errors associated with averaging time, intensity, or both, far outweigh the errors associated with choosing a rational distribution or an independent distribution of time and intensity in the prediction. This observation is generally true whenever an organism is exposed to UV light in a flow through reactor such that the range of doses is within the portion of the inactivation curve exhibiting strong exponential decay.     

Epidemiologic and pathologic aspects of an epizootic of malignant catarrhal fever in exotic hoofstock

An epizootic of malignant catarrhal fever (MCF) occurred at the Los Angeles Zoological Park which resulted in the deaths of four exotic ungulates. The source of infection was considered to be a newly purchased wildebeest bull (Connochaetes taurinus taurinus) that had been negative for antibody to MCF virus by an indirect immunofluorescent test. The need to re-evaluate regulations for the transportation and housing of young wildebeest is emphasized by this MCF outbreak. The diagnostic technology now available for identifying asymptomatic carriers of MCF virus and the present understanding of the behavior and pathogenesis of this highly cell-associated herpesvirus in exotic ruminants should provide a basis for the prevention and control of MCF in zoological parks.     

Comparative histopathological alterations in the digestive gland of marine bivalves exposed to Cu and Cd.

This study compares the histopathological alterations in the digestive gland cells of mussels, Mytilus galloprovincialis and clams, Ruditapes phillipinarum following exposure to copper and cadmium. The results show degenerative processes undergone in the digestive gland ranging from inflammatory responses to extreme vacuolation, particularly in Cd-exposed individuals. Unsaturated neutral lipids tend to accumulate in pathologically enlarged lysosomes of the homogeneous-type or heterogeneous-type depending of the species and of metal. Lipofucsins containing granules were mainly found in Cu-exposed mussels and Cd-exposed clams. No granules were detected in Cd-mussels. The comparison of the methods indicate that paraffin sections are also a suitable material for the localization of lipofucsins.