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Biomedical subjects

A D Ross

Publications and source records attributed to A D Ross.

At least 19 recordsLinked to original sources
PubMed2003

Clinical Toxoplasma gondii, Hammondia heydorni, and Sarcocystis spp. infections in dogs.

Concurrent infections with coccidians Toxoplasma gondii, Sarcocystis spp., and a Hammondia heydorni-like parasite were identified in tissues of three littermate pups on a Kelpie dog breeding farm in Australia. In total, 20 pups in four litters had died following vaccination with an attenuated distemper virus vaccine. Toxoplasma gondii tachyzoites were identified immunohistochemically in tissues of two dogs. Sarcocystis sp. sporocysts were seen in the intestinal lamina propria of two dogs. Asexual and sexual stages of H. heydorni-like parasite were found in enterocytes of the small intestine of two dogs. Ultrastructural development of schizonts and gamonts of this parasite is described. None of the protozoa in these dogs reacted with antibodies to Neospora caninum. Feeding of uncooked tissue of sheep was considered to be the likely source of infection for these coccidians in dogs.

Animal Feed↗
PubMed2001

Reproductive disease and congenital malformations caused by Menangle virus in pigs.

OBJECTIVE: To describe a new syndrome characterised by embryonic mortalities, stillbirths, mummified foetuses and congenital malformations in a herd of intensively farmed pigs. DESIGN: Field observations, laboratory investigations and examination of breeding records. PROCEDURE: Pathology examinations were performed on mummified and congenitally deformed piglets during an outbreak of reproductive disease at a 2600 sow intensive piggery in New South Wales from April to October 1997. Reproductive performance was monitored during the outbreak and breeding records were examined retrospectively. Serum and tissue samples from pigs were tested for evidence of infection with known porcine pathogens and for a new virus, Menangle virus, isolated from stillborn piglets with deformities from the affected piggery in August 1997. RESULTS: Reproductive disease occurred sequentially in all four breeding units at the affected piggery over a period of 21 weeks. The farrowing percentages in each unit decreased from 80 to 82% before the outbreak to 63 to 78% during the outbreak and the number of live piglets per litter declined from a mean of 9.6 to 9.8 before the outbreak to 7.2 to 8.9 during the outbreak. The proportion of affected litters (litters with less than six liveborn piglets) was highest (64%) in the sixth week of the outbreak. Mummified foetuses, stillborn piglets with arthrogryposis, craniofacial deformities and degeneration of the brain and spinal cord, were observed along with occasional abortions. Sera from sows that produced affected litters contained neutralising antibodies against Menangle virus and there was evidence that this virus had been introduced to the piggery in February 1997. CONCLUSIONS: Reproductive disease in pigs due to Menangle virus was characterised by stillbirths, mummification, embryonic death and infertility, along with abortions, skeletal deformities and degeneration of the brain and spinal cord in affected foetuses and stillborn piglets.

Animals↗
PubMed2001

Epidemiology and control of Menangle virus in pigs.

OBJECTIVE: To describe the epidemiology and eradication of Menangle virus infection in pigs. DESIGN: Field observations and interventions, structured and unstructured serological surveys, prospective and cross-sectional serological studies and laboratory investigations. PROCEDURE: Serum samples were collected from pigs at a 2600-sow intensive piggery in New South Wales that experienced an outbreak of reproductive disease in 1997. Serum samples were also collected from piggeries that received pigs from or supplied pigs to the affected piggery and from other piggeries in Australia. Serum and tissue samples were collected from pigs at piggeries experiencing reproductive disease in New South Wales. Sera and faeces were collected from grey-headed flying foxes (Pteropus poliocephalus) in the region of the affected piggery. Serum samples were tested for neutralising antibodies against Menangle virus. Virus isolation was attempted from faeces. RESULTS: Following the outbreak of reproductive disease, sera from 96% of adult pigs at the affected piggery, including sows that produced affected litters, contained neutralising antibodies against Menangle virus. Neutralising antibodies were also detected in sera from 88% of finisher pigs at two piggeries receiving weaned pigs from the affected piggery. No evidence of Menangle virus infection was found in other piggeries in Australia. In cross-sectional studies at the affected piggery, colostral antibodies were undetectable in most pigs by 14 to 15 weeks of age. By slaughter age or entry to the breeding herd, 95% of pigs developed high antibody titres (> or = 128) against Menangle virus in the virus neutralisation test. Menangle virus was eradicated from the affected piggery following a program of serological testing and segregation. Neutralising antibodies against Menangle virus were also detected in P poliocephalus from two colonies in the vicinity of the affected piggery. Two piggery workers were infected with Menangle virus. There was no evidence of infection in cattle, sheep, birds, rodents, feral cats and a dog at the affected piggery. CONCLUSIONS: Serological evidence of infection with Menangle virus was detected in pigs at a piggery that had experienced reproductive disease, in pigs at two associated piggeries and in fruit bats in the region of the piggery. Two humans were infected. The mode of transmission between pigs is unknown, but spread by faecal or urinary excretion is postulated. This virus can be eradicated by the segregation of pigs into discrete age groups.

Animals↗
PubMed2000

Halo vest effect on balance.

OBJECTIVE: To determine the effect of a halo vest, a cervical orthosis, on clinically relevant balance parameters. DESIGN: Subjects performed unipedal stance (with eyes open and closed, on both firm and soft surfaces) and functional reach, with and without the application of a halo vest. SUBJECTS: A convenience sample of 12 healthy young subjects, with an equal number of men and women. OUTCOME MEASURES: Seconds for unipedal stance (maximum 45); inches for functional reach. RESULTS: Both unipedal stance times and functional reach (mean +/- standard deviation) were significantly decreased with the halo vest as compared to without it (29.1+/-5.8 vs. 32.8+/-6.4 seconds, p = .002; 12.9+/-1.4 vs. 15.1+/-2.1 inches, p<.01). CONCLUSION: A halo vest causes an acute impairment in balance in the healthy young. It is likely that the impairment would be greater in older or injured patients, thus increasing their risk for a fall, which could have devastating consequences.

Adult↗
PubMed1999

Eastern movement therapies.

Tai chi, qigong, and yoga represent a class of exercise that differs from the routine strengthening and stretching programs currently employed in physical medicine. These techniques incorporate a "mind-body" approach to the rehabilitation of disorders commonly seen by physical medicine and rehabilitation clinicians. Research into the efficacy of these techniques clearly is in the beginning stages. What little has been conducted thus far is promising. These methods may serve to add valuable contributions to the continuity of care of ambulatory and non-ambulatory patients.

Asia↗
PubMed1998

An in-vitro test for assessing the viability of Ascaris suum eggs exposed to various sewage treatment processes.

A simple procedure using Ascaris suum as a model for Ascaris lumbricoides in testing the ability of sludge treatment processes to kill the eggs of parasitic roundworms was developed. Unembryonated and embryonated A. suum eggs were placed in a mesophilic anaerobic sludge digester or a sludge lagoon, or stored at 4 degrees C. Unembryonated eggs were recovered and incubated at 32.5 degree C and 90-95% r.h. for 48 h and viable eggs developed embryos consisting of two or more clearly defined cells. This viability was confirmed by further incubation for 30 days, when motile first-stage larvae were seen. Infectivity was demonstrated by administering larvated eggs to worm-fee pigs and recovering adult worms from the small intestine at necropsy. After 1 week in a mesophilic anaerobic digester, 95% of A. suum eggs produced two-cell larvae into vitro, with 86% progressing to motile larvae. After 5 weeks in the digester 51% progressed to motile larvae. Between 42% and 49% of eggs stored in a sludge lagoon for 29 weeks were viable and able to develop motile larvae. In the case of eggs that were embryonated before treatment, > 98% survived up to 5 weeks in the digester and were able to develop motile larvae. More than 90% of embryonated eggs survived for 29 weeks in the sludge lagoon and were able to develop motile larvae.

Anaerobiosis↗
PubMed1998

Circulating neutrophils and liver injury in rat models of experimental alcoholic liver disease.

The present study examined the relationship between circulating neutrophils and liver injury in two widely used rat models of chronic ethanol administration. Hematological alterations, liver histopathology, and biochemical indices of liver injury were assessed in rats receiving chronic ethanol by oral liquid diet feeding (Lieber-DeCarli method) or by continuous intragastric infusion (Tsukamoto-French method). Oral administration of ethanol did not affect circulating neutrophil counts, but resulted in minimal liver injury characterized by elevated serum alanine aminotransferase (79%), increased liver mass (15%), and moderate steatosis. In contrast, rats receiving ethanol by continuous intragastric infusion showed an approximately 2-fold increase in circulating neutrophils, and a moderate degree of liver injury, indicated by a 169% elevation of serum alanine aminotransferase and a 2-fold increase in liver mass. Liver biopsies from these rats showed severe steatosis and scattered necrotic hepatocytes, and some neutrophil infiltrates. To determine whether an increase in the number of circulating neutrophils could potentiate liver injury induced by oral ethanol feeding, rats were treated with human recombinant granulocyte colony-stimulating factor at a dose of 100 microg/kg/day (s.c.) for 4 days. Treatment with granulocyte colony-stimulating factor resulted in a 6- to 9-fold increase in circulating neutrophil counts. Nevertheless, this change did not enhance the minor degree of ethanol-induced liver injury in this model. Our results indicate that, whereas neutrophil leukocytosis accompanies more severe manifestations of ethanol hepatotoxicity in rats, this condition per se does not directly induce or exacerbate ethanol-induced liver injury.

Animals↗
PubMed1998

Effect of antithyroid drugs on hydroxyl radical formation and alpha-1-proteinase inhibitor inactivation by neutrophils: therapeutic implications.

The release of proteolytic enzymes and generation of strong oxidants such as the hydroxyl radical by activated neutrophils has been proposed to play an important role in mediating toxin-induced liver injury. The antithyroid drug propylthiouracil protects against liver injury induced by many hepatotoxic agents and markedly reduces mortality in patients with alcoholic liver disease. However, the mechanism(s) by which propylthiouracil protects against liver injury is not well understood. The present studies investigate the effect of antithyroid drugs on proteolytic enzyme activity and on hydroxyl radical generation from activated neutrophils. In the presence of hydrogen peroxide and chloride, neutrophil myeloperoxidase, an enzyme from the same gene superfamily as thyroid peroxidase, generates hypochlorous acid which inactivates alpha-1-proteinase inhibitor (A1PI) present in serum. This inactivation allows neutrophil-released proteolytic enzymes to attack cells. In the present study myeloperoxidase activity was inhibited fully at therapeutic concentrations by antithyroid drugs (propylthiouracil and methimazole). Antithyroid drugs fully prevented hypochlorous acid formation, and prevented neutrophil-mediated inactivation of A1PI, with concomitant blockage of proteolytic activity. Conversely, generation of both superoxide and hydroxyl radicals by activated neutrophils was unaffected by propylthiouracil. The production of these oxygen radicals was fully inhibited by the NADPH oxidase inhibitor diphenylene iodonium chloride, however. These studies indicate that antithyroid drugs are unlikely to prevent cell injury by inhibiting hydroxyl radical generation or by scavenging hydroxyl radicals, but are likely to exert their hepatoprotective anti-inflammatory action by inhibiting neutrophil myeloperoxidase, an enzyme akin to thyroid peroxidase.

Animals↗
PubMed1995

Effect of propylthiouracil treatment on NADPH-cytochrome P450 reductase levels, oxygen consumption and hydroxyl radical formation in liver microsomes from rats fed ethanol or acetone chronically.

The antithyroid drug propylthiouracil (PTU) has been shown previously to reduce hepatic oxygen utilization and to protect the liver from ethanol-induced injury. The present study examined the effect of PTU on hepatic microsomal oxygen consumption and on the activities of NADPH-cytochrome P450 reductase (CYP-reductase) and cytochrome P4502E1 (CYP2E1) in rats receiving ethanol or acetone chronically. Liver microsomes from rats treated with ethanol for 29 days displayed increases in (i) O2 consumption (70%), (ii) hydroxyl radical (.OH) production (49%) and (iii) ethanol oxidation (50%). Microsomal CYP2E1 levels were increased markedly by chronic ethanol administration, while CYP-reductase was affected marginally, but not significantly (P = 0.06). Chronic treatment with acetone for 14 days, produced similar effects, except that .OH production was not enhanced. Administration of PTU (25 mg/kg/day) to ethanol- or acetone-fed rats, for 10 and 14 days, respectively, led to a marked reduction in the levels and activity of CYP-reductase, and to a decrease in the rates of microsomal O2 consumption, .OH production and ethanol oxidation, but did not lower the levels of CYP2E1 or the metabolism of the CYP2E1 substrate N,N-nitrosodimethylamine. These data suggest that the ability of PTU to protect the liver from ethanol-induced injury may be due to a reduction in the levels of CYP-reductase, thereby minimizing the enhancement of microsomal oxygen consumption and free radical generation associated with ethanol-induced CYP2E1 activity.

Acetone↗
PubMed1993

Restriction-endonuclease analysis of Australian isolates of Leptospira interrogans serovar hardjo from cattle with agalactia and abortion.

Polyacrylamide gel electrophoresis and agarose gel electrophoresis were used to resolve restriction endonuclease digests of 20 Australian Isolates of Leptospira interrogans cultured from urine samples of cattle with agalactia and abortion. The restriction endonuclease profiles of 19 isolates closely matched the profiles of L interrogans serovar hardjo subtype hardjobovis reference strains. The remaining isolate had a different restriction profile from subtype hardjobovis and subtype hardjoprajitno reference strains and was serologically identified as serovar pomona. Silver staining of polyacrylamide gels gave enhanced resolution of restriction fragments compared with the traditional method of ethidium bromide staining of agarose gels.

Abortion, Veterinary↗
PubMed1992

Risk characterisation and management of sewage sludge on agricultural land--implications for the environment and the food-chain.

The disposal of sewage wastes may cause severe environmental problems as was graphically demonstrated with pollution on Sydney's ocean beaches in recent years. Sewage sludges contain valuable plant nutrients and organic matter which can improve the fertility and structure of the soil. However, human parasites, pathogenic micro-organisms and chemicals capable of causing soil contamination, phytotoxicity and residues in animal products may also be present. Although sewage sludge is frequently spread on agricultural land overseas, it is not common in Australia and most states do not have specific regulations to minimise risk and promote good practice. A sludge-to-land program began in the Sydney region in 1990. It follows guidelines written by NSW Agriculture to encourage beneficial agricultural use of sludge by adoption of environmentally sustainable practices. This article describes the major risks to the food-chain and the environment, which may be associated with applying sewage sludge to agricultural land. It summarises how the risks are managed, and where further research data are required.

Animals↗
PubMed1990

Vasopressin does not mediate the inhibition of ethanol drinking by the renin-angiotensin system.

Manipulations which are known to enhance activity in the renin-angiotensin system (RAS) have been found to reduce the voluntary consumption of ethanol in rats. Since angiotensin II is a potent stimulus for the release of vasopressin (VP), it is possible that the RAS modulates ethanol (ETOH) consumption through a mechanism involving VP. The present investigation examined the effect of peripheral injections of arginine-VP (AVP) and desglycinamide-AVP (DGAVP) on ETOH consumption in rats given daily one-hour access to ETOH. Daily subcutaneous treatment with AVP or DGAVP had no effect on ETOH consumption at doses ranging from 2 to 200 micrograms/kg (SC). Blood pressure was substantially elevated following a single 20 microgram/kg injection of AVP, indicating that AVP was biologically active at doses which failed to alter ethanol consumption. These findings indicate the VP does not affect established ETOH drinking and furthermore is not likely a critical factor in the reduction of ETOH intake by the RAS.

Alcohol Drinking↗
PubMed1990

Prostaglandin E2 reduces voluntary ethanol consumption in the rat.

A number of prior studies have suggested that the prostaglandins may mediate some of the physiological effects of ethanol, and while it has been suggested that PGE2 may be involved in regulating ethanol consumption, evidence for this has been inconclusive. In the present study, rats injected with PGE2 at doses of 50, 100 and 200 micrograms/kg consumed significantly less alcohol than vehicle-treated controls. Doses of PGE2 which were highly effective in reducing ethanol intake produced only marginal changes in the consumption of water and glucose solution. These data, together with previous studies demonstrating a link between ethanol and the prostaglandins, suggest that PGE2 may be involved in the control of ethanol consumption.

Alcohol Drinking↗
PubMed1990

Efficacy, safety, and quality-of-life assessment of captopril antihypertensive therapy in clinical practice.

Successful long-term treatment of hypertension must include consideration of individual patients' life-style interfaced with the potential for adverse drug events. In a postmarketing surveillance study, 30,515 patients received captopril monotherapy and were evaluated by 7792 physicians. Mean systolic and diastolic blood pressures were reduced 17 and 11 mm Hg, respectively. Mean diastolic blood pressure was reduced 10% for patients with mild hypertension; larger mean reductions were noted for patients with moderate (16.5%) and severe (21.5%) hypertension. Captopril therapy was equally effective in all races (white, Hispanic, and black patients), age groups, and in isolated instances of systolic hypertension. Only 4.9% of patients reporting an adverse event required discontinuation of therapy. Headache (1.8%) and dizziness (1.6%) were the most frequently reported adverse events. Quality-of-life measures improved.

Adult↗
PubMed1989

Nutritional myopathy in goats.

A nutritional myopathy in unweaned fibre goats aged 2 to 4 mths is described in 3 flocks from the tablelands of New South Wales. Clinically affected animals were illthrifty and in circulatory failure prior to being found dead. At necropsy, there was pronounced ascites, pulmonary congestion and marked mottling of the liver. Chalky white streaks and patches were obvious in the myocardium, particularly in the right ventricular wall. Skeletal muscles varied from grossly normal to generally pale. Histologically, the myocardium exhibited areas of severe acute myonecrosis with mineralisation and adjoining areas of phagocytosis and fibrosis. In 2 of 3 flocks, some skeletal muscles showed a mild subacute myopathy. Marked hepatic congestion extended to periacinar haemorrhage and necrosis in some areas. Dietary imbalances of selenium, vitamin E and polyunsatured fatty acids were probable factors in the pathogenesis of the condition.

Animals↗