Haemoglobin and oxygen transport of the West Australian dhufish, Glaucosoma hebraicum Richardson, and other species

To better understand the possible role of deoxygenation of haemoglobin in the pathogenesis of exophthalmos in the West Australian dhufish, Glaucosoma hebraicum Richardson, some oxygen transport properties of haemoglobin from this species were determined and compared with haemoglobin from black bream, Acanthopagrus butcheri (Munro), snapper, Pagrus auratus (Bloch & Schneider) and King George whiting, Sillaginodes punctata (Cuvier). Dhufish had a single haemoglobin with a pronounced Root effect. Snapper and black bream blood had six and five types of haemoglobin, respectively. The magnitude of the Root effect of haemoglobins in the haemolysate was demonstrated by comparing oxygenation and total deoxygenation at pH 8 with relative deoxygenation at pH 6.9. Dhufish haemoglobin demonstrated a large Root effect, with the Root effect of King George whiting, snapper and black bream being of lesser magnitude. Deoxygenation of all haemolysates was more pronounced in the presence of adenosine triphosphate (ATP). Seasonal changes in haematological parameters and ATP content of dhufish blood were not evident. The Root effect is discussed in the context of its possible role in oxygen supply to the retina and adaptation to the fish's habitat and the environment.     

Pathogenesis and epidemiology of spontaneous exophthalmos in the West Australian dhufish, Glaucosoma hebraicum Richardson

The West Australian dhufish, Glaucosoma hebraicum Richardson (family Glaucosomatidae) is a potentially valuable aquaculture species, but spontaneous exophthalmos is common in freshly caught and cultured dhufish. To investigate the epidemiology and pathogenesis of exophthalmos in tanks of wild-caught and captive-bred dhufish, records of culture conditions, the prevalence of lesions and pathological examinations were used to study the disease and associated environmental and management factors. Naturally occurring cases of exophthalmos that were examined were mostly unilateral and occurred more frequently in summer months during periods of increasing water temperature. In 15 affected eyes that were examined histologically gas bubbles and haemorrhages were consistently present in the choroid. In some, gas bubbles and haemorrhage were also present in retrobulbar tissues associated with perforation of the sclera. Oxygen concentrations were measured in 12 exophthalmic eyes and concentrations of 50–73% were recorded in gas bubbles in the anterior chamber of three of these that were acute cases. Very low oxygen tensions were recorded at the retinal–vitreal junction of four eyes with retrobulbar haemorrhages indicating that there may have been disruption of arterial blood supply to the choroid in chronic lesions or with perforation of the sclera. The results of experiments to determine the significance of exercise, high water temperature, sudden increases in light intensity, fish handling or tank cleaning indicate that exercise and/or high water temperature (25.5 °C) may be important risk factors for the development of exophthalmos in dhufish. Possible mechanisms for the formation of gas bubbles and haemorrhage in the choroid are discussed.     

Application of a Hall-effect transducer for measurement of tendon strains in horses

Custom-designed Hall-effect strain sensors (HES) were implanted surgically onto the superficial digital flexor tendons of the forelimbs of 4 adult Thoroughbreds. Strains were recorded at various gaits, using a portable amplifer and FM cassette recorder. Strain calculations used the original length (L) as the HES position with the forelimb in the relaxed neutral position during anesthesia. A characteristic deflection in the strain cycle recording was confirmed to correspond to initial hoof contact with the ground (heel strike) by simultaneous recording of weight bearing via a footswitch. Heel strike was used as the reference point to determine the magnitude of strain change during weight bearing and nonweight bearing under various conditions. The weight-bearing strains (heel strike to maximal strain) recorded in 2 horses (with a rider) were 3.1% and 7.6% at the walk, 6.5% and 10.1% at the trot, and 11.5% and 16.6% at the gallop. Strain rate during tendon loading at the gallop was approximately 200%/s. The magnitude of strain change during nonweight bearing (minimal strain to heel strike) was smaller than during weight bearing, but also increased with faster gaits. In 3 horses led at the walk and trot, modest increases in hoof angle (baseline 52 degrees) resulted in small increases in the magnitude of strain change during weight bearing at the trot, but the magnitude of strain change at the walk was not affected. Results of the study indicated that the HES can be successfully adapted to provide continuous strain measurement without subjective signs of discomfort or lameness in horses during or after instrumentation.     

Diversity of pilin of serologically distinct Bacteroides nodosus.

Pili from 11 distinct serotypes of Bacteroides nodosus were examined for diversity of pilin polypeptide subunits among serotypes and for purity of the pilin preparations. The pilin of all 11 samples was shown to be homogeneous. Mean +/- SD molecular weight of the pilin of 7 serotypes (A198, IV, V, VI, IX, XVII, and XVIII) was 18,500 +/- 100. The pilin of serotypes I, III, and VIII had molecular weight of 17,600, 19,400, and 19,000, respectively. Serotype XV differed greatly from the other 10 serotypes in that 2 distinct polypeptide bands with molecular weight of approximately 7,800 and 6,200 were detected. We suggest that these 2 low molecular weight bands resulted from proteolytic cleavage of the pilin protein.     

Isolation of Haemophilus somnus antigens and their use as vaccines for prevention of bovine thromboembolic meningoencephalitis

Antigens extracted from Haemophilus somnus were examined for their suitability as vaccines for prevention of thromboembolic meningoencephalitis and as antigens in immunologic tests for detection of susceptible cattle. Saline extraction of whole H somnus cells produced an outer membrane complex (OMC) that contained 2 major antigens when tested against antiserum to intact cells by immunoelectrophoresis. Anion exchange chromatography was used to separate an anionic antigen (AA) from the more cationic antigen (CA). According to chemical analysis and polyacrylamide gel electrophoresis, both AA and CA were complex mixtures--probably, outer membrane fragments. Enzyme-linked immunosorbent assays were used to measure serum levels of immunoglobulin (Ig) G and IgM against AA and CA in cattle vaccinated with whole cells, OMC, CA, or AA. Protection of vaccinated cattle was assessed after IV challenge exposure to H somnus. Moderate IgG and IgM responses occurred when cattle were given 2 vaccinal doses of 0.1 mg or 1.0 mg of whole cells, OMC, or AA. Two of 10 cattle given 2 vaccinal doses (1.0 mg) of OMC died after IV challenge exposure, whereas 8 of the 10 controls died, indicating significant protection (P less than 0.05). All of the 10 cattle given 2 vaccinal doses (1.0 mg) of AA were protected from IV challenge exposure, whereas 5 controls died (P less than 0.05). Two vaccinal doses of either 0.1 mg or 1.0 mg of CA produced high IgG and IgM responses. However, 3 of 10 cattle given 2 vaccinal doses (1.0 mg) of CA died after IV challenge exposure, as did 3 of the 10 controls, indicating that CA was not protective.(ABSTRACT TRUNCATED AT 250 WORDS)     

Fibronectin concentration in plasma of mares and neonatal foals

Plasma fibronectin concentrations were measured in clinically healthy mares and their neonatal foals, using a modified human fibronectin competitive enzyme-linked immunosorbent assay. Ranges of plasma fibronectin were established in clinically healthy horses, and the assay was reliable and reproducible. Plasma fibronectin concentrations were similar in mares and foals, both before and after colostrum ingestion.