OS061. Placental growth factor reduces blood pressure and proteinuria in experimental preeclampsia.

INTRODUCTION: Preeclampsia is a disorder related to an imbalance in the angiogenesis axis manifesting as endothelial dysfunction. Animal and human studies have shown that sFLT-1 (soluble fms like tyrosine kinase 1) is increased and PlGF (placental growth factor) reduced during the disease state. There are a paucity of studies investigating the clinical significance of normalising angiogenic axis. OBJECTIVES: To use a non-human primate uteroplacental ischemic (UPI) model of preeclampsia to assess if reversing the angiogenic imbalance, by increasing circulating PlGF, is able to ameliorate the hypertension and proteinuria. METHODS: Hypertensive proteinuria was induced in a non-human primate (Papio hamadryas) by ligation of a unilateral uterine artery at 130days of an 182day pregnancy. After two weeks of UPI, PlGF was administered by subcutaneous injection (100mg/kg/day) for 5 days (n=3) or normal saline in an equivalent volume (n=3). Blood pressure was monitored via intra-arterial radiotelemetry, sFLT-1 measured via ELISA and spot urinary protein:creatinine ratios were measured to monitor proteinuria. Data was analysed using SPSS by t-tests and analysis of repeated measures. Significance was set at p<0.05 and data expressed as the mean ±SEM. RESULTS: After two weeks of UPI both groups demonstrated a significant elevation in blood pressure, proteinuria (p<0.05) and sFLT-1 (p<0.001). The systolic BP increased by 12.4±2.3mmHg and 11.7±2.9mmHg in the PlGF and control groups respectively compared to baseline (p<0.005). After PlGF administration, there was a significant reduction in blood pressure in the treated group (-5.2s±0.8mmHg) compared to the increase in BP in the control group (+6.5±3mmHg). Proteinuria also reduced in the treated group from 112±51mg/mmol to 38±12mg/mmol whilst proteinuria in the control group was unchanged. The total circulating sFLT-1 was not significantly affected by the administration of PlGF after 5days. Although this study was not designed to assess fetal safety or outcomes, there was no adverse fetal outcome attributable to the administration of the PlGF. CONCLUSION: Administration of PlGF resulted in a reduction in BP and proteinuria without significantly affecting total sFLT-1 levels. Correcting the angiogenic axis imbalance may improve the clinical parameters in a non-human primate animal model of preeclampsia.

Group impressions as dynamic configurations: the tensor product model of group impression formation and change.

Group impressions are dynamic configurations. The tensor product model (TPM), a connectionist model of memory and learning, is used to describe the process of group impression formation and change, emphasizing the structured and contextualized nature of group impressions and the dynamic evolution of group impressions over time. TPM is first shown to be consistent with algebraic models of social judgment (the weighted averaging model; N. Anderson, 1981) and exemplar-based social category learning (the context model; E. R. Smith & M. A. Zárate, 1992), providing a theoretical reduction of the algebraic models to the present connectionist framework. TPM is then shown to describe a common process that underlies both formation and change of group impressions despite the often-made assumption that they constitute different psychological processes. In particular, various time-dependent properties of both group impression formation (e.g., time variability, response dependency, and order effects in impression judgments) and change (e.g., stereotype change and group accentuation) are explained, demonstrating a hidden unity beneath the diverse array of empirical findings. Implications of the model for conceptualizing stereotype formation and change are discussed.

A condition for designing bus-route type access site surveys to estimate recreational fishing effort.

A theoretical framework for using bus-route surveys to estimate recreational fishing effort has been established by taking into account the arrival and departure distributions of the fishing parties. Properties of a fishing effort estimator proposed by Robson and Jones (1989) are investigated. It is found that the estimator is not automatically unbiased; rather, a condition on the survey design has to be satisfied in order to be unbiased. The condition is simple and can be easily implemented.

Phage types of Australian isolates of Salmonella enterica subsp. enterica serovar Virchow.

Australian isolates (79) of Salmonella enterica subsp. enterica serovar Virchow (Salmonella Virchow) were characterized by phage typing. Thirteen phage types were identified, of which phage type (PT) 8, representing 54 of 79 isolates, was predominant, as it had been in England and Wales up to 1994 when it was replaced by PT26. Other phage types identified in Australia were distinct from those observed in England and Wales. This suggests that PT8 may be a global phage type, while others may be distinct to particular geographical regions.

Multilocus enzyme electrophoretic (MEE) analysis of Australian isolates of Salmonella enteritidis.

Seventy-three Australian isolates of Salmonella Enteritidis (SE) were analysed by multilocus enzyme electrophoresis (MEE) using a polyacrylamide gel system. Analysis of 11 enzyme loci identified eight electrophoretic types (ETs), with 61 of the isolates assigned to ET1, and 72 isolates considered to represent a clonal lineage. Representative isolates of each of the Australian ETs were then compared with isolates from England, Germany and the United States, using a starch gel system and 13 enzyme loci. The overseas isolates formed a single ET with representatives of the major Australian ET. It is concluded that Australian isolates of SE are closely related genetically to those from countries in which egg-borne transmission is common.

Sensitivity of Australian isolates of Salmonella enteritidis to nitrofurantoin and furazolidone.

Susceptibility of 66 and 62 Australian isolates of Salmonella enteritidis to nitrofurantoin and furazolidone, respectively, was determined. Most isolates were susceptible to both antibiotics. Cross-resistance was low among all isolates, but higher among the subset of phage type 4 isolates. These results contrast directly with those of a previous study (Rampling, A., Upson, R. and Brown, D.F.J. (1990) J. Antimicrob. Chemother., 25: 285-290). Sensitivity among Australian isolates of S. enteritidis does to some extent, support the contention that furans may have played a role in the selection and enhanced colonisation of poultry by Salmonella enteritidis in Britain. Furthermore, nitrofurantoin should not be used as a selective agent in the isolation of Salmonella enteritidis.

Plasmid analysis of Australian strains of Salmonella enteritidis.

Using an in-well lysis technique, 73 Australian strains of Salmonella enteritidis were shown to possess a large plasmid, similar in size to that possessed by a reference phage type 4 strain. Restriction analysis of the large plasmid from nine strains using EcoRI, HindIII and PstI suggested that these plasmids are similar to or the same as the 38 MDa plasmid described in strains of this species from other parts of the world.

Keratitis in free-ranging koalas (Phascolarctos cinereus) on Magnetic Island, Townsville.

Seventy free-ranging koalas (Phascolarctos cinereus) from Magnetic Island (Queensland, Australia) underwent an ocular examination, blood collection and serological examination for Chlamydia psittaci antibodies, and an examination of their teeth and genitalia. In 12 koalas long-standing unilateral keratitis was noted and in another 10 animals long-standing bilateral keratitis was observed. All animals were seronegative for Chlamydia psittaci and apart from some nasal discharge and a variety of assorted medical findings there was no sign of chlamydial infection. These ocular findings probably represent a new disease of unknown etiology.

The effect of immunosuppression on resistance to Rhodococcus equi in mice.

Rhodococcus equi, a natural pathogen of horses, produces lesions in mice following experimental infection. The effect of various immunosuppressing agents on the sequential development of these lesions has been assessed by measuring the growth of R. equi following intravenous or intranasal challenge and by histological examination. Cyclophosphamide treatment of mice, challenged intranasally, resulted in the development of lesions not unlike that seen in experimental and natural infection in foals. Cortisone acetate also impaired bacterial clearance from the lungs and affected the accumulation of mononuclear cells at infective foci. Most of the agents chosen to impair macrophage function failed to affect the resistance of mice to R. equi. Carbon, carrageenan and silica failed to alter significantly the growth kinetics of R. equi. Dextran sulphate depressed the rate of pulmonary clearance of organisms and affected the ability of animals to eliminate R. equi following rechallenge. Overall, these results support other evidence that cell mediated immunity is involved in host resistance to R. equi and that activated macrophages play a role in acquired immunity to this organism.

Early events associated with experimental infection of the murine lung with Rhodococcus equi.

Pneumonia due to Rhodococcus equi was induced in the murine lung by deposition of a known dose of organisms. From serial estimations of bacterial numbers in the lungs of inoculated mice, analysis of the cellular composition of bronchoalveolar lavage fluid and morphological examination of the lungs, events in the host-parasite interaction were followed until day 7. Early bacterial clearance from the lung was dose-dependent but was not sustained. A proportion of the inoculated R. equi was susceptible to the early nonspecific phagocytic cell response, and the contribution of neutrophils to bacterial clearance appeared largely limited to the first 24 hours. A substantial fraction of the organisms survived in the alveoli, probably within macrophages. The contribution phagocytes make to resistance against R. equi is similar to that which prevails in infection with Listeria monocytogenes.

Characterization of Rhodococcus equi-like bacterium isolated from a wound infection in a noncompromised host.

A case of superficial wound infection in a noncompromised host due to a Rhodococcus equi-like organism, acquired from soil, is described. The strain grew poorly at 37 degrees C and showed several differences from wild-type R. equi in biochemical tests and in its fatty acid and mycolic acid compositions.

Experimental infection of mice with Rhodococcus equi: differences in virulence between strains.

The growth kinetics in outbred mice of clinical and environmental isolates of Rhodococcus equi were followed by serial bacterial enumeration of organ homogenates. Clinical isolates multiplied until Day 4 before being progressively cleared, but could still be recovered from the liver at 3-4 weeks post-infection. Intravenous inoculation of clinical strains was associated with histopathological responses very similar to those elicited by intravenous infection with various facultative intracellular parasites. Whereas lesions in mice and foals at 7-9 days following respiratory infection are those of severe bronchopneumonia with massive consolidation, a week later the patterns of host response have diverged as the murine lesions resolve. The type strain, NCTC 1621 and 4-6 environmental isolates were eliminated without prior multiplication and these strains caused negligible lesions. The two environmental strains which behaved as the clinical strains were recovered from a stud with an R. equi problem. No association of colonial morphology of R. equi with virulence was apparent.

The immunological response of foals to Rhodococcus equi: a review.

Normal horses of all ages regularly show evidence of having responded immunologically to R. equi, thus adding serological support to epidemiological evidence that this organism is a normal intestinal inhabitant. More animals from "diseased" farms show a stronger antibody response when compared with foals from "healthy" farms. Various serological tests have been used to detect evidence of infection and to relate antibody level to severity of disease. Anti-R. equi IgG antibody levels, as measured by ELISA, are raised significantly during natural infection. Clinical severity of pneumonia can be correlated with lower specific antibody responses. Following experimental infection, immunological responses can be detected by complement fixation, indirect immunofluorescence, ELISA, lymphocyte blastogenesis and skin testing. Very little work has been carried out to evaluate vaccines against R. equi infection and results have not been encouraging. Success in treatment has been reported following passive immunisation. Administration of immune leucocyte extracts has had no effect on morbidity or mortality rates. The widespread distribution of this organism, together with the relative infrequency of disease caused by it, suggest that R. equi may initiate infection only in such circumstances as a very high infectious challenge, immunological immaturity or deficiency in the host and genetic predisposition.

A note on hydrolytic enzymes of Corynebacterium equi.

One hundred and five strains of Corynebacterium equi from various sources were examined for the production of 11 extracellular enzymes. Only lipase and phosphatase activity were detected in all strains. A small number of strains produced deoxyribonuclease but these strains were not confined to any one source. It seems likely that C. equi does not rely on a powerful array of extracellular enzymes to induce pathology.

Antibiotic susceptibility testing: caeci caecos ducentes?

Antibiotic susceptibility testing is frequently conducted by diagnostic laboratories and some clinicians rely on the information which such testing provides. In this review of the procedure the rationale for interpretation of the agar diffusion test is outlined and the factors which affect determination of zone size and minimum inhibitory concentration (MIC) discussed. The relationship between zone size and MIC is considered, as well as the clinical relevance of MIC breakpoints. Against this background we assess the value of disc diffusion tests for veterinary practice.

Capsular serotypes of Rhodococcus equi.

One hundred strains of Rhodococcus equi from various animal species and sources in Australia were examined for capsular serotype. Eighty-four of the strains fell into the existing 7 serotypes, and just under half of the strains belonged to serotype 1. Isolates from the intestines and faeces of horses, cattle, pigs and other species, and from soil, were found to belong to the same serotypes as those recovered from the lungs of foals with R. equi pneumonia. There was no clear relationships between capsular serotype and source of origin of the isolates.

An operant tracking procedure in the auditory assessment of profoundly retarded individuals.

The present study investigated a discrete-trials, operant tracking and a descending-series procedure for the determination of hearing levels with profoundly retarded individuals. These individuals were previously diagnosed as untestable. Following stimulus-control training with errorless discrimination procedures, hearing levels for each individual were examined with both procedures. For P-1 and P-2, the operant tracking procedure was administered following a descending-series procedure. Both were observed to "track" their own hearing levels. For P-3, the operant tracking procedure was administered first, followed by the descending-series procedure. Although P-3 also "tracked" her own hearing level, more variable responding was observed. Nonetheless, the operant tracking procedure proved quite workable and may provide for improved hearing testing with "difficult-to-test" individuals.