Rapid transplacental infection with bovine pestivirus following intranasal inoculation of ewes in early pregnancy

Despite the importance of congenital viral infections in both veterinary and human medicine, only limited experimental work has been carried out to elucidate the mechanisms involved in transplacental virus infections. To further an understanding of fetal infection with pestiviruses, the distribution of bovine pestivirus in the uterine and fetal tissues of ewes in early pregnancy, following a natural route of infection, was investigated. On the 18th day of pregnancy, nine ewes were inoculated by the intranasal route with 1 X 10(5) 50% tissue culture infective doses of an Australian isolate of noncytopathic bovine pestivirus (bovine viral diarrhea virus genotype 1). All ewes were ovariohysterectomized at approximately 100 hours postinfection. Samples from the reproductive tract and conceptus were examined histologically and tested for bovine pestivirus by nested reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry and for interferon-tau mRNA expression by nonnested RT-PCR. Although no histopathologic changes were observed in the maternal or fetal tissues, virus was detected in the reproductive tract of all nine ewes and in all of the conceptuses examined. Al; the time of surgery, only two of the nine ewes were demonstrably viremic. This study demonstrates that bovine pestivirus can spread from a natural site of infection to the ovine fetus within 4 days in the absence of maternal immunity and despite the presence of interferon expression in the reproductive tract.

Analysis of the study design and manuscript deficiencies in research articles submitted to Emergency Medicine

Objective: To describe and analyse the study design and manuscript deficiencies in original research articles submitted to Emergency Medicine. Methods: This was a retrospective, analytical study. Articles were enrolled if the reports of the Section Editor and two reviewers were available. Data were extracted from these reports only. Outcome measures were the mean number and nature of the deficiencies and the mean reviewers’ assessment score. Results: Fifty-seven articles were evaluated (28 accepted for publication, 19 rejected, 10 pending revision). The mean (± SD) number of deficiencies was 18.1 ± 6.9, 16.4 ± 6.5 and 18.4 ± 6.7 for all articles, articles accepted for publication and articles rejected, respectively (P = 0.31 between accepted and rejected articles). The mean assessment scores (0–10) were 5.5 ± 1.5, 5.9 ± 1.5 and 4.7 ± 1.4 for all articles, articles accepted for publication and articles rejected, respectively. Accepted articles had a significantly higher assessment score than rejected articles (P = 0.006). For each group, there was a negative correlation between the number of deficiencies and the mean assessment score (P > 0.05). Significantly more rejected articles ‘… did not further our knowledge’ (P = 0.0014) and ‘… did not describe background information adequately’ (P = 0.049). Many rejected articles had ‘… findings that were not clinically or socially significant’ (P = 0.07). Common deficiencies among all articles included ambiguity of the methods (77%) and results (68%), conclusions not warranted by the data (72%), poor referencing (56%), inadequate study design description (51%), unclear tables (49%), an overly long discussion (49%), limitations of the study not described (51%), inadequate definition of terms (49%) and subject selection bias (40%). Conclusions: Researchers should undertake studies that are likely to further our knowledge and be clinically or socially significant. Deficiencies in manuscript preparation are more frequent than mistakes in study design and execution. Specific training or assistance in manuscript preparation is indicated.

Natural abundance of stable carbon and nitrogen isotopes in Cannabis sativa reflects growth conditions

Stable carbon and nitrogen isotope signatures (delta C-13 and delta N-15) of Cannabis sativa were assessed for their usefulness to trace seized Cannabis leaves to the country of origin and to source crops by determining how isotope signatures relate to plant growth conditions. The isotopic composition of Cannabis examined here covered nearly the entire range of values reported for terrestrial C-3 plants. The delta C-13 values of Cannabis from Australia, Papua New Guinea and Thailand ranged from -36 to -25 parts per thousand, and delta N-15 values ranged from -1.0 to 15.8 parts per thousand. The stable isotope content did not allow differentiation between Cannabis originating from the three countries, but delta C-13 values of plantation-grown Cannabis differed between well-watered plants (average delta C-13 of -30.0 parts per thousand) and plants that had received little irrigation (average delta C-13 of -26.4 parts per thousand). Cannabis grown under controlled conditions had delta C-13 values of -32.6 and -30.6 parts per thousand with high and low water supply, respectively. These results indicate that water availability determines leaf C-13 in plants grown under similar conditions of light, temperature and air humidity. The delta C-13 values also distinguished between indoor- and outdoor-grown Cannabis; indoor- grown plants had overall more negative delta C-13 values (average -31.8 parts per thousand) than outdoor-grown plants (average -27.9 parts per thousand). Contributing to the strong C-13-depletion of indoor- grown plants may be high relative humidity, poor ventilation and recycling of C-13-depleted respired CO2. Mineral fertilizers had mostly lower delta N-15 values (-0.2 to 2.2 parts per thousand) than manure-based fertilizers (7.6 to 22.7 parts per thousand). It was possible to link delta N-15 values of fertilizers associated with a crop site to soil and plant delta N-15 values. The strong relationship between soil, fertilizer, and plant delta N-15 suggests that Cannabis delta N-15 is determined by the isotopic composition of the nitrogen source. The distinct delta N-15 values measured in Cannabis crops make delta N-15 an excellent tool for matching seized Cannabis with a source crop. A case study is presented that demonstrates how delta C-13 and delta N-15 values can be used as a forensic tool.

Resolution of natural groups using iterative assignment tests: an example from two species of Australian native rats (Rattus)

Sympatric individuals of Rattus fuscipes and Rattus leucopus, two Australian native rats from the tropical wet forests of north Queensland, are difficult to distinguish morphologically and are often confused in the field. When we started a study on fine-scale movements of these species, using microsatellite markers, we found that the species as identified in the field did not form coherent genetic groups. In this study, we examined the potential of an iterative process of genetic assignment to separate specimens from distinct (e.g. species, populations) natural groups. Five loci with extensive overlap in allele distributions between species were used for the iterative process. Samples were randomly distributed into two starting groups of equal size and then subjected to the test. At each iteration, misassigned samples switched groups, and the output groups from a given round of assignment formed the input groups for the next round. All samples were assigned correctly on the 10th iteration, in which two genetic groups were clearly separated. Mitochondrial DNA sequences were obtained from samples from each genetic group identified by assignment, together with those of museum voucher specimens, to assess which species corresponded to which genetic group. The iterative procedure was also used to resolve groups within species, adequately separating the genetically identified R. leucopus from our two sampling sites. These results show that the iterative assignment process can correctly differentiate samples into their appropriate natural groups when diagnostic genetic markers are not available, which allowed us to resolve accurately the two R. leucopus and R. fuscipes species. Our approach provides an analytical tool that may be applicable to a broad variety of situations where genetic groups need to be resolved.

Dendritic cells rapidly undergo apoptosis in vitro following culture with activated CD4(+) V alpha 24 natural killer T cells expressing CD40L

Human V alpha 24 natural killer T (V alpha 24NKT) cells are activated by -glycosylceramide-pulsed dendritic cells (DCs) in a CDld-dependent and T-cell receptor-mediated manner. There are two major subpopulations of V alpha 24NKT cells, CD4(-) CD8(-) V alpha 24NKT and CD4(+) V alpha 24NKT cells. We have recently shown that activated CD4(-) CD8 V alpha 24NKT cells have cytotoxic activity against DCs, but knowledge of the molecules responsible for cytotoxicity of V alpha 24NKT cells is currently limited. We aimed to investigate whether CD4(+) V alpha 24NKT cells also have cytotoxic activity against DCs and to determine the mechanisms underlying any observed cytotoxic activity. We demonstrated that activated CD4(+) V alpha 24NKT cells [CD40 ligand (CD40L) -positive] have cytotoxic activity against DCs (strongly CD40-positive), but not against monocytes (weakly CD40-positive) or phytohaemagglutinin blast T cells (CD40-negative), and that apoptosis of DCs significantly contributes to the observed cytotoxicity. The apoptosis of DCs following culture with activated CD4(+) V alpha 24NKT cells, but not with resting CD4(+) V alpha 24NKT cells (CD40L-negative), was partially inhibited by anti-CD40L mAb, Direct ligation of CD40 on the DCs by the anti-CD40 antibody also induced apoptosis of DCs. Our results suggest that CD40-CD40L interaction plays an important role in the induction of apoptosis of DCs following culture with activated CD4+ Va24NKT cells. The apoptosis of DCs from normal donors. triggered by the CD40-CD40L interaction, may contribute to the homeostatic regulation of the normal human immune system, preventing the interminable activation of activated CD4(+) V alpha 24NKT cells by virtue of apoptosis of DCs.

The natural history of Hendra and Nipah viruses

Pteropid bats (flying foxes), species of which are the probable natural host of both Hendra and Nipah viruses, occur in overlapping populations from India to Australia. Ecological changes associated with land use and with animal husbandry practices appear most likely to be associated with the emergence of these two agents. (C) 2001 Editions scientifiques et medicales Elsevier SAS.

Brain natriuretic peptide: Disease marker or more in cardiovascular medicine?

Brain natriuretic peptide (BNP) is predominantly a cardiac ventricular hormone that promotes natriuresis and diuresis, inhibits the renin-anglotensin-aldosterone axis, and is a vasodilator. Plasma BNP levels are raised in essential hypertension, and more so in left ventricular (LV) hypertrophy and heart failure. Plasma BNP levels are also elevated in ischemic heart disease. Attempts have been made to use plasma BNP levels as a marker of LV dysfunction, but these have shown that plasma BNP levels are probably not sensitive enough to replace echocardiography in the diagnosis of LV dysfunction. Pericardial BNP or N-BNP may be more suitable markers of LV dysfunction. Plasma BNP levels are also elevated in right ventricular dysfunction, pregnancy-induced hypertension, aortic stenosis, age, subarachnoid hemorrhage, cardiac allograft rejection and cavopulmonary connection, and BNP may have an important pathophysiological role in some or all of these conditions. Clinical trials have demonstrated the natriuretic, diuretic and vasodilator effects, as well as inhibitory effects on renin and aldosterone of infused synthetic human BNP (nesiritide) in healthy humans. BNP infusion improves LV function in patients with congestive heart failure via a vasodilating and a prominent natriuretic effect. BNP infusion is useful for the treatment of decompensated congestive heart failure requiring hospitalization. The clinical potential of BNP is limited as it is a peptide and requires infusion. Drugs that modify the effects of BNP are furthering our understanding of the pathophysiological role and clinical potential of BNP. Increasing the effects of BNP may be a useful therapeutic approach in heart failure involving LV dysfunction. The levels of plasma BNP are increased by blockers, cardiac glycosides and vasopeptidase inhibitors, and this may contribute to the usefulness of these agents in heart failure. (C) 2001 Prous Science. All rights reserved.

SOX18 and the transcriptional regulation of blood vessel development

SOX18 is a transcription factor that is transiently expressed in nascent endothelial cells during embryonic development and adult neovascularization. This protein belongs to the SOX family of transcription factors, ih,which are proving to be some of the key regulators of cell-type specification in the vertebrate embryo. Natural mutations in the Sox18 gene have been shown to result to cardiovascular dysfunction, in some cases leading to death. Available evidence thus implicates Sox18 as an important regulator of vascular development, most likely playing a key role in endothelial cell specification. However; the genetic knockout of Sox18 in mice has produced a confounding result that complicates our understanding of the molecular mode of action of the SOX18 protein. We speculate that Sox18 inky act in a redundant fashion with closely related genes such as Sox7 and/or Sox17. (C) 2001, Elsevier Science Inc.

Expression of the hepatitis C virus structural proteins in mammalian cells induces morphology similar to that in natural infection

Like many positive-strand RNA viruses, replication of the hepatitis C virus (HCV) is associated with cytoplasmic membrane rearrangements. However, it is unclear which HCV Proteins induce these ultrastructural features. This work examined the morphological changes induced by expression of the HCV structural proteins, core, E1 and E2, expressed from a Semliki Forest Virus (SFV) recombinant RNA replicon. Electron microscopy of cells expressing these proteins showed cytoplasmic vacuoles containing membranous and electron-dense material that were distinct from the type I cytoplasmic vacuoles induced during SFV replicon replication. Immunogold labelling showed that the core and E2 proteins localized to the external and internal membranes of these vacuoles. At times were also associated with some of the internal amorphous material. Dual immunogold labelling with antibodies raised against the core protein and against an endoplasmic reticulum (ER)-resident protein (protein disulphide isomerase) showed that the HCV-induced vacuoles were associated with ER-labelled membranes. This report has identified an association between the HCV core and E2 proteins with induced cytoplasmic vacuoles which are morphologically similar to those observed in HCV-infected liver tissue, suggesting that the HCV structural proteins may be responsible for the induction of these vacuoles during HCV replication in vivo.