Topographic and keratometric astigmatism up to 1 year following small flap trabeculectomy (microtrabeculectomy).

AIM: To determine the induced corneal astigmatism by measuring the changes in manual keratometry and computerised corneal videokeratoscopy up to 1 year following small flap trabeculectomy (microtrabeculectomy). METHOD: A prospective study of a case series of small flap trabeculectomy procedures performed at the 90 degree meridian on 16 eyes of 16 patients, all followed to 1 year postoperatively. Changes in manual keratometry and computerised videokeratoscopy (Eyesys) readings were analysed by vector analysis and vector decomposition techniques. RESULTS: By vector analysis, the mean surgically induced refractive change (SIRC) cylinder power vectors induced at 1, 3, 6, and 12 months as measured by manual keratometry were 0.68, 0.38, 0.52, and 0.55 dioptres, and by keratography 0.75, 0.66, 0.59, and 0.64 dioptres. Vector decomposition on the induced vector cylinders on manual keratometry resulted in a "with the rule" mean vector of 0.52 and 0.22 dioptres at 1 and 3 months and an "against the rule" mean vector of 0.16 and 0.16 dioptres at the same time points (p=0.03 and 0.28 respectively). Vector decomposition at 6 and 12 months revealed no significant with the rule changes induced. Similar analysis on the videokeratoscopy results revealed significant induced with the rule astigmatism until 3 months, but not at 6 and 12 months postoperatively. CONCLUSION: Small flap trabeculectomy (microtrabeculectomy) produces smaller changes in corneal curvature that resolve sooner than previous reports of larger flap techniques.

Effect of different bedding materials on the reproductive performance of mice.

Vermiculite, pine shavings and unbleached eucalyptus pulp contact-bedding were compared using the number of litters and individuals born and weaned, mortality rates at different stages of the lactation period, and the weight increase of pups as evaluation indices for bedding quality. These bedding materials exerted different effects on the reproductive performance of the same mouse strain. The same is true for the effect of a specific bedding material on different mouse strains. These effects are most pronounced during the first 4 days of life. As a whole, the results demonstrated that eucalyptus pulp was the better bedding type, followed by pine shavings and vermiculite. The latter material had a detrimental effect on the mating success of AKR mice.

The in vivo effect of different bedding materials on the antioxidant levels of rat heart, lung and liver tissue.

Several experimental effects due to wood-derived bedding have been reported. Female Sprague Dawley rats were kept on pine shavings, eucalyptus pulp, vermiculite and in wire-bottomed cages without bedding for 14 days whereafter normal values for the antioxidants ascorbic acid and reduced glutathione (G-SH) in rat heart lung and liver tissue were determined and compared. Statistically significant differences were observed for lung G-SH between pine shavings and eucalyptus pulp (p < 0.0183), and heart G-SH between vermiculite and eucalyptus pulp (p < 0.0948). The highest levels of liver G-SH were obtained using pine shavings compared to vermiculite (p < 0.0001), eucalyptus pulp (p < 0.0002) and wire floor (p < 0.0001). Statistically significant differences in ascorbic acid concentrations could only be described between the wire-bottomed cages and eucalyptus pulp (p < 0.0333) for lung tissue and between pine shavings and eucalyptus pulp for liver tissue (p < 0.042). Although no statistically significant differences were observed in heart ascorbic acid levels between the different bedding applications, the concentration obtained using vermiculite was approximately 50% higher than that observed with the other materials. Pine shavings, eucalyptus pulp and wire floors demonstrated virtually the same heart tissue ascorbic acid levels. It was thus demonstrated that bedding material can alter the tissue antioxidant concentration of laboratory animals, limiting the comparison of this type of result between institutions to those using identical environmental conditions.

The dust content, dust generation, ammonia production, and absorption properties of three different rodent bedding types.

Vermiculite, pine shavings and unbleached eucalyptus pulp contact bedding were compared for dust content, dust production (as a result of animal activity), moisture absorption properties and ammonia production. The percentage of dust particles <300 microm found in pine shavings and vermiculite was 18 and 8 times greater respectively than was found in eucalyptus pulp. The lowest ammonia levels (<1-1 ppm), measured on day 7, were obtained using eucalyptus pulp. Although the ammonia levels obtained for vermiculite compared very well with those of pulp, high levels of dust, up to 5 times more than pulp, were experienced with vermiculite. Pine shavings were associated with the highest ammonia concentration (1-3 ppm), but produced approximately 50% less dust than vermiculite. The water absorption properties obtained for pulp were between 35% and 76% higher than those obtained for vermiculite and pine shavings respectively.

The in vitro enzyme-inducing and cytotoxic properties of South African laboratory animal contact bedding and nesting materials.

Enzyme-inducing and cytotoxic effects of South African bedding materials were investigated using a mouse hepatoma cell line, Hepa-1, cell culture system. This cell culture system is a convenient and sensitive method for the screening of bedding materials for the presence of compounds that could be potentially harmful to animals and thus the experimental outcome. Cells were exposed to acetone extracts of the different materials or their components. Corn cobs displayed very little or no CYP1A1-inducing or cytotoxic effects, whilst vermiculite and unbleached pulp from pine and eucalyptus showed greater induction and cytotoxic properties. The latter properties were lower than those produced by the different recycled paper extracts. Pine shavings (Pinus elliottii) and the different wood components making up industrial sawdust expressed the highest cytotoxic and CYP1A1-inducing properties.

Laboratory animal bedding and nesting materials for rodents and lagomorphs: the South African situation.

The different bedding and nesting materials used for small laboratory animals (mice, rats, hamsters, guinea pigs, and rabbits) by different institutions (n = 27) in South Africa were investigated by making use of questionnaires. A response of 81.5% was obtained. Twenty-two per cent of the respondents made exclusive use of direct (contact) bedding materials, whilst the rest used both direct (breeding) and indirect (nonbreeding) bedding methods. Three institutions did not use bedding materials for indirect bedding applications. Ten different bedding and nesting materials were identified. Non-sterile materials were used by 57% (indirect bedding), 44% (direct bedding), and 42% (nesting material) of the respondents. Between 7 and 22% of the respondents did however use both sterile and non-sterile materials for the different applications.

Rhipicephalus zambeziensis unlikely to transmit foot-and-mouth disease virus.

The potential of the ixodid tick, Rhipicephalus zambeziensis, was investigated as a vector in the transstadial transmission of the foot-and-mouth disease virus by feeding nymphae on viraemic (log 1.0-4.0 TCID50/ml) cattle. Suspensions were prepared, at various intervals after detachment, from pools of engorged nymphae--some of which were allowed to moult first. Suspensions were inoculated into sucking mice, cell cultures and, in some cases, cattle to detect the FMD virus. Newly moulted adult ticks, derived from nymphae which had fed on viraemic cattle, were also allowed to feed on susceptible cattle. The pattern of virus detection indicated that the FMD virus was capable of surviving at least 3 d in engorged nymphae, but less than 7 d following repletion. It was concluded that R. zambeziensis is unlikely to transmit the FMD virus.

The transovarial transmission of Babesia trautmanni by Rhipicephalus simus to domestic pigs.

Rhipicephalus simus was, for the first time, experimentally proven to be a transovarial vector of Babesia trautmanni of domestic pigs. The nymphal and adult progeny of experimentally infected female ticks transmitted the infection to 2 susceptible splenectomized pigs. Features of the infection included a prepatent period of 6-8 days post-tick infestation, a febrile reaction for 3 days and a maximum parasitaemia score of 15 (more than 6 parasites per 300 red blood cells). Other clinical signs in both pigs were mild inappetence and listlessness. Both pigs recovered without any antibabesial therapy.

Lenticular chalcosis--electron microscopic and microprobe analysis. A case report.

A patient with a retained intra-ocular foreign body had a lens extraction for lenticular chalcosis. The lens capsule, examined under an electron microscope, showed copper particles deposited in the basement membrane. The lens capsule and foreign body were examined with an electron microprobe beam. This method proved to be an efficient method of qualitative and quantitative analysis of the contents of the foreign body.

Transmission and diagnosis of equine babesiosis in South Africa.

The transmission and prevalence of Babesia equi and B. caballi are being studied. Rhipicephalus evertsi mimeticus an ixodid tick from Namibia was identified as a new vector of B. equi, however, R. turanicus, previously reported to be a vector, failed to transmit both B. equi and B. caballi in the laboratory. The accurate diagnosis of B. caballi is being investigated because the nature of its low level parasitaemia does not allow easy detection in thin blood smears, routinely used for diagnosis, by clinicians. Consequently its role as a pathogen remains obscure. The importance of identifying infected horses, destined for export to Babesia-free countries, is also stressed. Thick and thin blood smears, serology (IFAT) and DNA probes are currently employed to study disease prevalence. To date 293 healthy, adult, thoroughbred horses have been screened by all three methods. The percentage positives are as follows: B. equi 4.4%, 70.6%, 13% and B. caballi 0.7%, 37%, 18.4% respectively. The DNA probes were more sensitive than blood smear examination for diagnosing carrier infections but are probably not sensitive enough to identify all carrier infections. A poor correlation was found between detection of the parasites' DNA and seropositivity. However, polymerase chain reaction could be used to amplify parasite DNA in a particular sample and this could result in more accurate diagnosis.

Transmission and diagnosis of equine babesiosis in South Africa

The transmission and prevalence of Babesia equi and B. caballi are being studied. Rhipicephalus evertsi mimeticus an ixodid tick from Namibia was identified as a new vector of B. equi, however, R. turanicus, previously reported to be a vector, failed to transmit both B. equi and B. caballi in the laboratory. The accurate diagnosis of B. caballi is being investigated because the nature of its low level parasitaemia does not allow easy detection in thin blood smears, routinely used for diagnosis, by clinicians. Consequently its role as a pathogen remains obscure. The importance of identifying infected horses, destined for export to Babesia-free coutries, is also stressed. Thock and thin blood smears, serology (IFAT) and DNA probes are currently employed to study disease prevalence. To date 293 healthy, adult, throughbred horses have been screened by all three methods. The percentage positives are as follows: B. equi 4.4%, 70.6%, 13% and B. caballi 0.7%, 37%, 18.4% respectively. The DNA probes were more sensitive than blood smear examination for diagnosing carrier infections but are probably not sensitive enough to identify all carrier infections. A poor correlation was found between detection of the parasites' DNA and seropositivity. However, polymerase chain reaction could be used to amplify parasite DNA in a particular sample and its could result in more accurate diagnosis

Laboratory animal bedding: a review of specifications and requirements.

The literature is reviewed regarding existing specifications and requirements for laboratory animal bedding. The lack of comprehensive specifications in the guidelines of laboratory animal governing bodies, and the introduction of external variables by unsuitable bedding into experimental design, are discussed on the basis of examples from the literature.

Evaluation of an electronic device used as a quick screening method to detect changes in the red cell content of the blood in horses participating in endurance trail rides.

Dehydration, to varying degrees, will inevitably occur in horses participating in endurance trail rides. This water loss is directly related to the amount of body water lost through evaporative cooling, that in turn being related to the amount and rate of work performed, and to the environmental temperature and humidity. An electronic apparatus that can substitute for the conventional and time-consuming venous haematocrit was developed to measure the animals' hydration status. The mechanism of this electrometer is based upon the relationship between the red cell content and the electrical conductivity of the blood. The electrometer reading gave a significant correlation (p less than 0.001) with the venous haematocrit, thus indicating that the electrometer is a reliable apparatus for determining the animals' hydration status within seconds of venepuncture.

The isolation and transmission of an unidentified Babesia sp. to cattle by Hyalomma truncatum Koch 1844.

An unidentified Babesia sp. which causes a mild disease in cattle was isolated in a splenectomized ox that received pooled blood from field cattle. That this organism is pleomorphic and resembles Babesia occultans makes it difficult to differentiate between these organisms microscopically. Initially, it was suspected that this Babesia could be B. occultans. Several attempts to transmit this parasite transovarially with Hyalomma marginatum rufipes, the vector of B. occultans, failed. Continued efforts to identify possible vectors, using Boophilus microplus, Rhipicephalus evertsi evertsi and Rhipicephalus appendiculatus, all failed. The only tick thus far identified that could have transmitted the infection transovarially in the adult stage was the two-host tick Hyalomma truncatum.

An attempt to improve the immunization of sheep against heart-water by using different combinations of 3 stocks of Cowdria ruminantium.

Neither sheep immune to the Ball 3, the Kwanyanga or the Mara stocks of Cowdria ruminantium nor those immunized with combinations of these 3 stocks were protected against challenge with the Mali stock. Against challenge with the Welgevonden stock, however, immunization with each of the 3 combinations and with single stocks effected a protective immunity.

Corridor disease in South Africa: a review of the current status.

The African buffalo (Syncerus caffer) is a reservoir host of Theileria parva lawrencei the causative organism of Corridor or buffalo disease of cattle. This organism can apparently transform its behaviour when tick-passaged through cattle to resemble that of Theileria parva parva, causing classic East Coast fever (ECF). These are major considerations for the strict quarantine measures imposed on buffaloes from Corridor disease endemic areas in South Africa. Results of continuing studies on diagnosis, chemotherapy, transmission and attempts to transform the behaviour of T.p. lawrencei in the laboratory, are discussed.

Parasites of domestic and wild animals in South Africa. XXIII. Helminth and arthropod parasites of warthogs, Phacochoerus aethiopicus, in the eastern Transvaal Lowveld.

A total of 69 warthogs, Phacochoerus aethiopicus, were collected from 4 localities within the Kruger National Park, eastern Transvaal Lowveld. These animals harboured 16 nematode species, 2 trematodes, 1 or 2 species of adult cestodes and the larval stages of 4 cestodes. No pattern of seasonal abundance could be determined for any of the helminths. The warthogs were also infested with 3 flea species, 1 louse species, 8 ixodid tick species, 1 argasid tick and the nymphae of a pentastomid. The seasonal abundance of fleas of the genus Echidnophaga, of the sucking louse Haematopinus phacochoeri and the ixodid ticks Amblyomma hebraeum, Rhipicephalus appendiculatus, Rhipicephalus simus and Rhipicephalus zambeziensis was determined.

Freeze-drying of Aegyptianella pullorum.

Heparinized whole blood, parasitized with Aegyptianella pullorum, was collected from 2 fowls. Buffered lactose peptone (BLP) was added v/v as a stabilizer and the mixture lyophilized in 2 ml aliquots after rapid or slow freezing. At different stages during the freeze-drying process, as well as after lyophilization and reconstitution with 1.8 ml of sterile water, samples were taken and injected into pullets. Infectivity was maintained throughout. However, the prepatent period was lengthened after freezing and particularly after lyophilization when there was some loss of viability.