Vermin of Proof: Arguments for the Admissibility of Animal Model Studies as Proof of Causation in Toxic Tort Litigation

Toxic torts is a body of law that aims to compensate individuals for harms they suffer from exposure to hazardous substances. To successfully bring a toxic tort claim, a plaintiff must prove the main elements of a general tort cause of action: duty, breach, causation, and damages. Causation in a toxic tort case is particularly challenging to prove given the nature of toxic substances. To prove the toxicant in question caused the damages alleged, plaintiffs often present expert testimony based on scientific studies. Animal model studies, in particular, can help factfinders understand the health implications of the toxicants at issue. However, judges, scholars, and other legal professionals are skeptical of the use of animal studies because of scientific and legal concerns, which range from interspecies disparities to prejudice of juries. These concerns are either unfounded or exaggerated. Animal model studies can be both reliable and relevant in toxic tort cases. Given the Federal Rules of Evidence, case law relevant to scientific evidence, and one of the goals of tort law-justice-judges should more readily admit these types of studies as evidence to help plaintiffs meet the burden of proof in toxic tort litigation

The effects of spinal anesthesia on the circulation in normal unoperated man with reference to the autonomy of the arterioles and especially those of the renal circulation

The present study, comprising observations on 21 subjects given high spinal anesthesia, is an investigation of the effects of anesthetic denervation in normal man, uncomplicated by surgical intervention, on the circulation with particular reference to the vascular bed of the kidney. It is concluded that the renal arterioles are distinctly autonomous, in the sense that under basal conditions the renal vascular tone is not affected by anesthetic denervation. Our observations further suggest that the arteriolar bed generally (apart from the skin) possesses considerably more autonomy than is usually attributed to it-sufficient, in fact, in the normal supine individual at rest, to maintain an essentially normal arterial pressure. We find no evidence of significant arteriolar dilatation during high spinal anesthesia, such reduction in blood pressure as occurs being attributable, we believe, to diminished circulating blood volume in consequence of dilatation of the capillaries, venules, and veins. Part I deals with the following topics: (1) Methods; (2) the effects of spinal anesthesia on renal blood flow; (3) on the arterial pressure, and (4) on the reflex responses to posture, hypercapnia, and anoxemia. Part II consists of a review of the evidence on (5) the existence of tonic vasoconstrictor activity and on (6) the existence of autonomy in the peripheral arterioles generally, and (7) in the kidney in particular, and (8) the peripheral effects of hypercapnia and anoxemia. In (5) it is brought out that the notion of tonic vasoconstrictor activity in the sympathetic nervQus system, apart from the skin, is based largely upon animal experiments which are seriously complicated by general anesthesia, venous dilatation, etc., and that the information so obtained cannot be transferred with confidence to normal animals, and certainly not to man. PART I Methods The subjects were male convalescent patients ranging in age from 18 to 50 years who, with a single exception, presented no abnormal signs contraindicating selection for this study. They were examined in the morning in the basal, fasting condition, and were prepared for the measurement of renal blood flow and filtration rate by the clearance method, as described by Smith, Goldring, and Chasis (93). In the earlier observations the phenol red and inulin (35) clearances were followed, but after the introduction of the diodrast clearance (93), all three clearances were used. The phenol red clearance serves as a check on the diodrast clearance, the constancy of the phenol red/diodrast clearance ratio before and after anesthesia demonstrating that procaine per se has no effect upon the tubular excretory mechanism. The infusions corresponded to the typical infusion cited by Chasis, Ranges, Goldring, and Smith (18). Zero time was taken as the beginning of the priming infusion, which occupied about 10 minutes; the infusion was then changed to the sustaining infusion, the first urine collection period being started at about 30 minutes. The sustaining infusion was usually interrupted momentarily to permit injection of the anesthetic, and a short washout period was allowed to reestablish blood levels of diodrast, etc. before the next urine collection period was started. The urine collection periods (10 to 15 minutes in length) were timed to 15 seconds, and all urine samples were collected by catheter with sterile precautions, the bladder being washed out with 20 cc. of saline. (In our opinion, single urine collection periods obtained by voluntary voiding, or even by catheterization without rinsing the bladder, may be highly inaccurate; we have made nearly 3000 catheterized and rinsed collections, and we recognize that it is impossible even by this method to empty the bladder completely every time.) All our observations have been made on the descending limb of water diuresis, and to prevent an excessive reduction of urine flow we have 31

Heart failure with mid-range ejection fraction in CHARM: characteristics, outcomes and effect of candesartan across the entire ejection fraction spectrum.

AIMS: We tested the hypothesis that candesartan improves outcomes in heart failure (HF) with mid-range ejection fraction [HFmrEF; ejection fraction (EF) 40-49%]. METHODS AND RESULTS: In 7598 patients enrolled in the CHARM Programme (HF across the spectrum of EF), we assessed characteristics, outcomes and treatment effect of candesartan according to EF. Patients with HFmrEF (n = 1322, 17%) were similar to those with HF with reduced EF (HFrEF; n = 4323, 57%) with respect to some characteristics, and intermediate between HFrEF and HF with preserved EF (HFpEF; n = 1953, 26%) with respect to others. Over a mean follow-up of 2.9 years, the incidence rates for the primary outcome of cardiovascular death or HF hospitalization were 15.9, 8.5 and 8.9 per 100 patient-years in HFrEF, HFmrEF and HFpEF. In adjusted analyses, the rates of the primary outcome declined with increasing EF up to 50%. For treatment effect, the incidence rates for the primary outcome for candesartan vs. placebo were 14.4 vs. 17.5 per 100 patient-years in HFrEF [hazard ratio (HR) 0.82, 95% confidence interval (CI) 0.75-0.91; P < 0.001], 7.4 vs. 9.7 per 100 patient-years in HFmrEF (HR 0.76, 95% CI 0.61-0.96; P = 0.02), and 8.6 vs. 9.1 per 100 patient-years in HFpEF (HR 0.95, 95% CI 0.79-1.14; P = 0.57). For recurrent HF hospitalization, the incidence rate ratios were 0.68 in HFrEF (95% CI 0.58-0.80; P < 0.001), 0.48 in HFmrEF (95% CI 0.33-0.70; P < 0.001), and 0.78 in HFpEF (95% CI 0.59-1.03; P = 0.08). With EF as a continuous spline variable, candesartan significantly reduced the primary outcome until EF well over 50% and recurrent HF hospitalizations until EF well over 60%. CONCLUSION: Candesartan improved outcomes in HFmrEF to a similar degree as in HFrEF. ClinicalTrials.gov: CHARM Alternative NCT00634400, CHARM Added NCT00634309, CHARM Preserved NCT00634712

Modulation of IL-17 and Foxp3 Expression in the Prevention of Autoimmune Arthritis in Mice

©2010 Duarte et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Background: Rheumatoid Arthritis (RA) is a chronic immune mediated disease associated with deregulation of many cell types. It has been reported that different T cell subsets have opposite effects in disease pathogenesis, in particular Th17 and Treg cells. Methodology and Findings: We investigated whether non-depleting anti-CD4 monoclonal antibodies, which have been reported as pro-tolerogenic, can lead to protection from chronic autoimmune arthritis in SKG mice – a recently described animal model of RA – by influencing the Th17/Treg balance. We found that non-depleting anti-CD4 prevented the onset of chronic autoimmune arthritis in SKG mice. Moreover, treated mice were protected from the induction of arthritis up to 60 days following anti-CD4 treatment, while remaining able to mount CD4-dependent immune responses to unrelated antigens. The antibody treatment also prevented disease progression in arthritic mice, although without leading to remission. Protection from arthritis was associated with an increased ratio of Foxp3, and decreased IL-17 producing T cells in the synovia. In vitro assays under Th17-polarizing conditions showed CD4-blockade prevents Th17 polarization, while favoring Foxp3 induction. Conclusions: Non-depleting anti-CD4 can therefore induce long-term protection from chronic autoimmune arthritis in SKG mice through reciprocal changes in the frequency of Treg and Th17 cells in peripheral tissues, thus shifting the balance towards immune tolerance.This work was funded by SUDOE, grant number IMMUNONET-SOE1/1P1/E014, and supported by a research grant from Fundação para a Ciência e Tecnologia (FCT), Portugal (FCT/POCI/SAU-MMO/55974/2004). JD, AA-D, and VGO are funded with scholarships from FCT (SFRH/BD/23631/2005, SFRH/BD/49093/2008, and SFRH/BPD/22575/2005)

Left atrial size and function in a South Asian population and their potential influence on the risk of atrial fibrillation

Background: South Asians have a low prevalence of atrial fibrillation (AF) compared with Caucasians despite having a higher prevalence of conventional risk factors for the arrhythmia. The reason for this disparity is uncertain but may be due to ethnic differences in atrial morphology. This study examines the association between ethnicity and left atrial (LA) size and function in South Asian and Caucasian subjects using the reference technique of cardiovascular magnetic resonance imaging (MRI). Hypothesis: South Asians have smaller LA size and therefore increased LA function. Methods: Retrospective case‐control study of 60 South Asian and 60 Caucasian patients who had undergone a clinically indicated MRI between April 2010 and October 2017 and had been found to have a structurally normal heart. LA and left ventricular (LV) volume and function were assessed and compared between the ethnicities. Results: In comparison with Caucasians, South Asians had significantly lower minimum (27.7 ± 11.1 mL vs 34.9 ± 12.3 mL, P = 0.002) and maximum LA volumes (64.7 ± 21.1 mL vs 80.9 ± 22.5 mL, P < 0.001), lower LV end‐diastolic volume (P < 0.001), lower LV stroke volume (P < 0.001), and lower LV mass (P = 0.022) and these values remained significant after correcting for body surface area. Further analysis revealed that LA volume was independently associated with South Asian ethnicity. There was no difference in LA function between the ethnic groups. Conclusions: South Asians have reduced LA volumes and a proportionally smaller heart size in comparison to Caucasians. Smaller LA size may protect against the development of AF by reducing the risk of reentrant circuit formation and atrial fibrosis development

Conversion of Membrane-bound Fas(CD95) Ligand to Its Soluble Form Is Associated with Downregulation of Its Proapoptotic Activity and Loss of Liver Toxicity

Human Fas ligand (L) (CD95L) and tumor necrosis factor (TNF)-α undergo metalloproteinase-mediated proteolytic processing in their extracellular domains resulting in the release of soluble trimeric ligands (soluble [s]FasL, sTNF-α) which, in the case of sFasL, is thought to be implicated in diseases such as hepatitis and AIDS. Here we show that the processing of sFasL occurs between Ser126 and Leu127. The apoptotic-inducing capacity of naturally processed sFasL was reduced by >1,000-fold compared with membrane-bound FasL, and injection of high doses of recombinant sFasL in mice did not induce liver failure. However, soluble FasL retained its capacity to interact with Fas, and restoration of its cytotoxic activity was achieved both in vitro and in vivo with the addition of cross-linking antibodies. Similarly, the marginal apoptotic activity of recombinant soluble TNF-related apoptosis-inducing ligand (sTRAIL), another member of the TNF ligand family, was greatly increased upon cross-linking. These results indicate that the mere trimerization of the Fas and TRAIL receptors may not be sufficient to trigger death signals. Thus, the observation that sFasL is less cytotoxic than membrane-bound FasL may explain why in certain types of cancer, systemic tissue damage is not detected, even though the levels of circulating sFasL are high

Immunoregulatory Mechanisms Underlying Prevention of Colitis-Associated Colorectal Cancer by Probiotic Bacteria

Background: Inflammatory bowel disease (IBD) increases the risk of colorectal cancer. Probiotic bacteria produce immunoregulatory metabolites in vitro such as conjugated linoleic acid (CLA), a polyunsaturated fatty acid with potent anticarcinogenic effects. This study aimed to investigate the cellular and molecular mechanisms underlying the efficacy of probiotic bacteria in mouse models of cancer. Methodology/Principal Findings: The immune modulatory mechanisms of VSL#3 probiotic bacteria and CLA were investigated in mouse models of inflammation-driven colorectal cancer. Colonic specimens were collected for histopathology, gene expression and flow cytometry analyses. Immune cell subsets in the mesenteric lymph nodes (MLN), spleen and colonic lamina propria lymphocytes (LPL) were phenotypically and functionally characterized. Mice treated with CLA or VSL#3 recovered faster from the acute inflammatory phase of disease and had lower disease severity in the chronic, tumor-bearing phase of disease. Adenoma and adenocarcinoma formation was also diminished by both treatments. VSL#3 increased the mRNA expression of TNF-a, angiostatin and PPAR c whereas CLA decreased COX-2 levels. Moreover, VSL#3-treated mice had increased IL-17 expression in MLN CD4+ T cells and accumulation of Treg LPL and memory CD4+ T cells. Conclusions/Significance: Both CLA and VSL#3 suppressed colon carcinogenesis, although VSL#3 showed greater anticarcinogeni

Murine and Bovine γδ T Cells Enhance Innate Immunity against Brucella abortus Infections

γδ T cells have been postulated to act as a first line of defense against infectious agents, particularly intracellular pathogens, representing an important link between the innate and adaptive immune responses. Human γδ T cells expand in the blood of brucellosis patients and are active against Brucella in vitro. However, the role of γδ T cells in vivo during experimental brucellosis has not been studied. Here we report TCRδ−/− mice are more susceptible to B. abortus infection than C57BL/6 mice at one week post-infection as measured by splenic colonization and splenomegaly. An increase in TCRγδ cells was observed in the spleens of B. abortus-infected C57BL/6 mice, which peaked at two weeks post-infection and occurred concomitantly with diminished brucellae. γδ T cells were the major source of IL-17 following infection and also produced IFN-γ. Depletion of γδ T cells from C57BL/6, IL-17Rα−/−, and GMCSF−/− mice enhanced susceptibility to B. abortus infection although this susceptibility was unaltered in the mutant mice; however, when γδ T cells were depleted from IFN-γ−/− mice, enhanced susceptibility was observed. Neutralization of γδ T cells in the absence of TNF-α did not further impair immunity. In the absence of TNF-α or γδ T cells, B. abortus-infected mice showed enhanced IFN-γ, suggesting that they augmented production to compensate for the loss of γδ T cells and/or TNF-α. While the protective role of γδ T cells was TNF-α-dependent, γδ T cells were not the major source of TNF-α and activation of γδ T cells following B. abortus infection was TNF-α-independent. Additionally, bovine TCRγδ cells were found to respond rapidly to B. abortus infection upon co-culture with autologous macrophages and could impair the intramacrophage replication of B. abortus via IFN-γ. Collectively, these results demonstrate γδ T cells are important for early protection to B. abortus infections