Evaluation and histological examination of a Campylobacter fetus subsp. venerealis small animal infection model

Bovine genital campylobacteriosis (BGC), caused by Campylobacter fetus subsp. venerealis, is associated with production losses in cattle worldwide. This study aimed to develop a reliable BGC guinea pig model to facilitate future studies of pathogenicity, abortion mechanisms and vaccine efficacy. Seven groups of five pregnant guinea pigs (1 control per group) were inoculated with one of three strains via intra-peritoneal (IP) or intra-vaginal routes. Samples were examined using culture, PCR and histology. Abortions ranged from 0% to 100% and re-isolation of causative bacteria from sampled sites varied with strain, dose of bacteria and time to abortion. Histology indicated metritis and placentitis, suggesting that the bacteria induce inflammation, placental detachment and subsequent abortion. Variation of virulence between strains was observed and determined by culture and abortion rates. IP administration of C. fetus subsp. venerealis to pregnant guinea pigs is a promising small animal model for the investigation of BGC abortion

Stochastic double dissociations in distributed models of semantic memory

We present a preliminary set of connectionist models of impairments to semantic memory, exploring the conditions under which double dissociations between knowledge of living and non-living entities occur. Small et al [1] argue that category specific impairments are a consequence of semantic feature based representations in a fully distributed memory system. Farah and McClelland [2] argue that category specific impairments arise due to modular structure in semantic memory, albeit structure that is specific to modality; they hypothesise that living and non-living entities have a differential reliance on perceptual and functional features. We evaluated these respective claims by lesioning a simple autoassociative model of semantic memory, using a 2x2 design: fully distributed architecture versus partially modular architecture with modality specific channels; Small et al’s training set versus a training set constructed according to Farah and McClelland’s perceptual/functional scheme. One thousand stochastic lesions were applied to each network ‘subject.’ The results supported Farah and McClelland: on average, double dissociations required modular structure and differential reliance on modalities. However, by choosing select (i.e. rare) lesions from each set of 1000, double dissociations of living versus non-living knowledge were found in both networks using both training sets. We discuss the idea that statistical distributions of impairments in patients with similar lesions are necessary to compare against the predictions of functional models, and thus that single case studies may be insufficient to distinguish distributed and modular architectures

Application of a Campylobacter fetus subspecies venerealis guinea pig infection model for the assessment of strain virulence variation

Bovine Genital Campylobacteriosis, caused by Campylobacter fetus subsp.venerealis is associated with production losses due to herd infertility and sporadic abortions. The aim of this study was to compare abortifacient properties between C. fetus subsp. venerealis strains. Four groups of 10 pregnant guinea pigs (4 vaccinated (VibrovaxTM twice, five weeks apart prior to mating) and 6 non-vaccinated) were challenged intraperitoneally at week five of gestation with four different strains at a concentration of 107 cfu/ml. Tissues from dams and foetuses were examined by culture. Proportions were compared using Fisher’s Exact test. Strain 76223 resulted in 8/10 abortions (6/6 non-vaccinated, 2/4 vaccinated), strain 924 2/10 (2/6 non-vaccinated, 0/4 vaccinated), strain 635 0/10 and strain B6 2/10 (1/6 non-vaccinated, 1/4 vaccinated), within 12 days (p=0.007). C. fetus subsp. venerealis was reisolated from peritoneum, uterus horns, placenta, amniotic fluid and foetal stomach contents in aborting and non-aborting animals. Reisolation was unsuccessful in five of the vaccinated animals. Virulence variation was present with differences in abortion rates and culture results. Intra-peritoneal administration of C. fetus subsp. venerealis to pregnant guinea pigs is a promising small animal model for investigation of C. fetus subsp. venerealis strain variation and abortion mechanisms

Experimental infections with Campylobacter fetus subspecies venerealis in cattle

Development of effective protocols to replicate the transmission of C. fetus subsp. venerealis in cattle is critical for the evaluation of the biology of the organism as well as the host immune response. Â Protocols for experimental infections with C. fetus venerealis in bulls and heifers were developed. A total of 6 Brahman bulls and 11 Brahman heifers were randomly allocated to four experimental groups containing exposed and unexposed animals. One group of bulls and one group of heifers were challenged by experimental exposure by intrapreputial and intracervical inoculation with a C. fetus venerealis suspension respectively. The remaining groups were challenged by natural mating with previously infected animals. Detection of C. fetus venerealis using culture and real-time PCR in smegma samples from bulls and cervico-vaginal samples from heifers; and macro and histological examination of tissue samples from the reproductive tracts collected after slaughter were performed. C. fetus venerealis was detected by culture and/or real time PCR in all groups post-challenge. Experimental exposure was more effective in establishing infection in bulls and heifers and the infectious status appeared to last longer (up to 10 weeks in bulls and 7 weeks in heifers). There was minimal cellular inflammatory response after experimental and natural challenge

Association of Timing of Plasma Transfusion With Adverse Maternal Outcomes in Women With Persistent Postpartum Hemorrhage

IMPORTANCE Early plasma transfusion for women with severe postpartum hemorrhage (PPH) is recommended to prevent coagulopathy. However, there is no comparative, quantitative evidence on the association of early plasma transfusion with maternal outcomes.OBJECTIVE To compare the incidence of adverse maternal outcomes among women who received plasma during the first 60 minutes of persistent PPH vs women who did not receive plasma for similarly severe persistent PPH.DESIGN, SETTING, AND PARTICIPANTS This multicenter cohort study used a consecutive sample of women with persistent PPH, defined as PPH refractory to first-line measures to control bleeding, between January 1, 2011, and January 1, 2013. Time-dependent propensity score matching was used to select women who received plasma during the first 60 minutes of persistent PPH and match each of them with a woman who had shown the same severity and received the same treatment of PPH but who had not received plasma at the moment of matching. Transfusions were not guided by coagulation tests. Statistical analysis was performed from June 2018 to June 2019.EXPOSURES Transfusion of plasma during the first 60 minutes of persistent PPH vs no or later plasma transfusion.MAIN OUTCOMES AND MEASURES Incidence of adverse maternal outcomes, defined as a composite of death, hysterectomy, or arterial embolization.RESULTS This study included 1216 women (mean [SD] age, 31.6 [5.0] years) with persistent PPH, of whom 932 (76.6%) delivered vaginally and 780 (64.1%) had PPH caused by uterine atony. Seven women (0.6%) died because of PPH, 62 women (5.1%) had a hysterectomy, and 159 women (13.1%) had arterial embolizations. Among women who received plasma during the first 60 minutes of persistent PPH, 114 women could be matched with a comparable woman who had not received plasma at the moment of matching. The incidence of adverse maternal outcomes was similar between the women, with adverse outcomes recorded in 24 women (21.2%) who received early plasma transfusion and 23 women (19.9%) who did not receive early plasma transfusion (odds ratio, 1.09; 95% CI, 0.57-2.09). Results of sensitivity analyses were comparable to the primary results.CONCLUSIONS AND RELEVANCE In this cohort study, initiation of plasma transfusion during the first 60 minutes of persistent PPH was not associated with adverse maternal outcomes compared with no or later plasma transfusion, independent of severity of PPH.Research into fetal development and medicin