Exploratory study of the 'weekend effect' for acute medical admissions to public hospitals in Queensland, Australia.

AIMS: To determine whether in-hospital deaths of patients admitted through emergency departments with acute exacerbations of chronic obstructive pulmonary disease (COPD), acute myocardial infarction, intracerebral haemorrhage and acute hip fracture are increased by weekend versus weekday admission (the 'weekend effect'). METHODS: We performed a retrospective analysis of statewide administrative data from public hospitals in Queensland, Australia, during the 2002/2003-2006/2007 financial years. The primary outcome was 30-day in-hospital mortality. The secondary outcome of 2-day in-hospital mortality helped determine whether increased mortality of weekend admissions was closely linked to weekend medical care. RESULTS: During the study period, there were 30 522 COPD, 17 910 acute myocardial infarction, 4183 acute hip fracture and 1781 intracerebral haemorrhage admissions. There was no significant weekend effect on 30-day in-hospital mortality for COPD (adjusted risk ratio = 0.92, 95% CI: 0.81-1.04, P= 0.222), intracerebral haemorrhage (adjusted risk ratio = 1.01, 95% CI: 0.86-1.16, P= 0.935) or acute hip fracture (adjusted risk ratio = 0.78, 95% CI: 0.54-1.03, P= 0.13). There was a significant weekend effect for acute myocardial infarction (adjusted risk ratio = 1.15, 95% CI: 1.03-1.26, P= 0.007). Two-day in-hospital mortality showed similar results. CONCLUSION: This is the first Australian study on the 'weekend effect' (in a cohort other than neonates), and the first study worldwide to assess specifically the weekend effect among COPD patients. Observed patterns were consistent with overseas research. There was a significant weekend effect for myocardial infarction. Further research is needed to determine whether location (e.g. rural), clinical (e.g. disease severity) and service provision factors (e.g. access to invasive procedures) influence the weekend effect for acute medical conditions in Australia.

Experimental inoculation of domestic pigeons (Columbia livia) and zebra finches (Poephila guttata) with Neospora caninum tachyzoites.

Dogs are a definitive host of Neospora caninum and cattle are intermediate hosts. Alternative life-cycles have not been investigated. Foxes are frequently seropositive, but may not commonly prey upon cattle; therefore, other intermediate hosts may exist that are frequent prey of foxes. Three domestic pigeons (Columbia livia) and three zebra finches (Poephila guttata) were inoculated with N. caninum tachyzoites, to determine if they could serve as intermediate hosts. Tissue culture, PCR, serology, and histology were all positive for one or more pigeons. All finches resisted infection. Further testing of columbiform birds as intermediate hosts of N. caninum is warranted.

Ingestion of Neospora caninum tissue cysts by Mustela species.

Dogs are a definitive host of Neospora caninum, a protozoal parasite that causes abortion in cattle. Mustelids were tested to determine if they could also be definitive hosts. The procedures used were the same as those previously used to test dogs. Ermine (Mustela erminea), weasels (Mustela frenata) and ferrets (Mustela putorius) were fed N. caninum-infected mice. Neospora caninum oocysts were not observed. Mustelid faeces were fed to mice. The mice did not seroconvert and N. caninum was not detected in murine brains using tissue culture and PCR. The hypothesis that Mustela spp. are definitive hosts of N. caninum is not supported.

Repetitive abortion in Neospora-infected ewes.

Pregnant ewes inoculated with cultured Neospora caninum tachyzoites in 1995, 1996, or 1995 and 1996 aborted or delivered weak or clinically normal lambs in 1996. Nine of 11 ewes in the study had previously produced infected lambs or fetuses after being experimentally infected in 1995. Fetuses and lambs produced in 1996 showed histologic lesions and zoites indicative of Neospora. Serologic responses and production of infected fetuses/lambs indicated systemic neosporosis in the ewes during gestation, although tachyzoites could not be cultured from maternal tissues. The repetitive infection of fetuses, and resulting clinical and histopathologic findings in the present study are similar to those reported in naturally infected cattle, adding to the already established similarities of neosporosis between sheep and cattle.

Dogs are definitive hosts of Neospora caninum.

Dogs were investigated to determine if they are definitive hosts of Neospora caninum. Four dogs were fed N. caninum tissue cysts in infected mouse tissue, and two negative control dogs were fed uninfected mouse tissue. Dog faeces were examined daily for 30 days using a sucrose flotation technique. Three challenged dogs shed spherical to subspherical unsporulated oocysts, measuring 10 to 11 microns in diameter. Oocysts sporulated within 3 days and contained two sporocysts, each with four sporozoites. Outbred, inbred, and gamma-interferon knockout mice were inoculated with canine faecal extracts and monitored for evidence of neosporosis using a variety of morphologic, immunohistologic, serologic, and genetic analyses. Mice that received faeces from each dog observed to shed oocysts were demonstrated to have neosporosis by two or more techniques. One mouse was demonstrated to be infected with N. caninum by immunohistochemistry, ultrastructural analysis, and a species-specific PCR test. No evidence of neosporosis was observed in control animals. Based on this study, dogs are a definitive host of Neospora caninum.

Oral inoculation of cats with tissue cysts of Neospora caninum.

OBJECTIVE: To test the hypothesis that cats are definitive hosts of Neospora caninum. ANIMALS: 6 weaned male kittens obtained from 2 sources, and several dozen outbred mice. PROCEDURE: Cats were fed large numbers of 3 strains of N caninum: tissue cysts in buffered saline solution, mouse brain homogenates, and whole carcass homogenates from seropositive mice. Fecal specimens were examined for 4 weeks by use of flotation tests, and bioassays were performed in mice. One cat was inoculated parenterally with tachyzoites, to determine whether cats could respond serologically to N caninum. Tissue cysts from portions of oral inocula were cultured to verify viability. Indirect fluorescent antibody serologic testing, histologic and immunohistologic examinations, cell culture, and polymerase chain reaction procedures were performed 4 to 8 weeks after oral exposure, to seek evidence of infection of cats and mice. RESULTS: None of the cats or mice seroconverted to N caninum, with the exception of the single cat inoculated parenterally. Fecal shedding of oocysts was not observed, except for Isospora felis oocysts that were shed by 2 cats beginning prior to oral challenge exposure. Evidence of infection was not detected in tissues of cats or mice, with the exception of the parenterally inoculated cat. CONCLUSIONS: The hypothesis that cats are definitive hosts of N caninum is not supported. CLINICAL RELEVANCE: Extermination of cats in efforts to control bovine neosporosis is not warranted.

Osmolarity is an independent trigger of Acanthamoeba castellanii differentiation.

Like many yeasts, bacteria, and other sporulating microorganisms, Acanthamoeba castellanii (Neff), a free-living amoeba with pathogenic relatives, differentiates into a dormant form when deprived of nutrients. Acanthamoeba cysts redifferentiate into trophozoites when food is resupplied. We report here that Acanthamoeba encystment is also triggered by elevated osmolarity, and that osmolarity and cell surface receptor binding are synergistic in triggering differentiation. Additions of sodium chloride or glucose to rich growth media were used to produce specific osmolarity increases and similar encystment results were obtained with either additive. Although many organisms, including Acanthamoeba and mammalian cells, have been shown to adapt to hyperosmolar conditions, this is the first demonstration that hyperosmolarity can be a primary differentiation signal.

The synthesis of poly-L-lysine-succinyl-NADP: an analogue for NADP/H.

Poly-L-lysine-succinyl-NADP, an analogue for nicotinamide adenine dinucleotide phosphate (NADP/H), has been synthesized by linking NADP/H to poly-L-lysine hydrobromide. This analogue (PL-SNP) was assayed with N, N dimethylaniline (DMA) in the presence of hepatic microsomal oxidase. A regeneration system of G-6-p and G-6-PD was used for reducing the PL-SNP+ to PL-SNPH. This reaction scheme with PL-SNP was found to exhibit up to 100% of the initial activity of pure NADP+ based on polarographic studies. Reaction rate of production for dimethylaniline oxide (DMA-0) was determined by oxygen consumption and by oxide formation. One of the potential uses of this analogue is as a cofactor in a membrane/liver enzyme detoxification system.

A model enzymic extracorporeal detoxification system.

Preliminary studies at the University of Oklahoma have incorporated the use of a continuous, seal-less blood centrifuge as an extracorporeal detoxification unit to aid in the removal of foreign chemicals from the blood. Detoxification is performed by immobilized enzymes in conjunction with a cofactor (NADPH) bound to a water-soluble macromolecule. A drug enters the device with the plasma and then passes across a semipermeable membrane which serves to retain the cofactor. At this point, a combination of the drug, the cofactor and the enzyme react to form the drug-oxide. The oxide then passes back through the membrane into the blood and back into the body. Concurrently, the macro-NADP+ is reduced by G-6-P and G-6-PD in the cofactor regeneration portion of the device. To facilitate detoxification, the centrifuge is employed to provide plasma rich in toxins, but void of potentially interfering blood components such as platelets and whole blood cells. These components tend to dilute the toxins or adhere to the interfacing membrane, decreasing the permeability of these toxins into the detoxification unit. It is felt that the centrifuge-detoxification combination will provide a potentially efficient hepatic assist device.