Biology subjects

Sargent, J.

Publications and source records attributed to Sargent, J..

4 recordsLinked to original sources

bioRxiv2025

Progression of the cardiac phenotype of the DE50-MD dog model of Duchenne Muscular Dystrophy, corroborating results of cardiac magnetic resonance imaging with pathology up to 36 months of age.

Cardiomyopathy is an expected consequence of the invariably fatal, X-linked muscle-wasting disease, Duchenne Muscular Dystrophy, (DMD) but onset and progression vary between individuals. Cardiac magnetic resonance imaging (CMR) is invaluable for identification of subclinical myocardial abnormalities, to stratify disease and to identify patients needing early therapeutic intervention. The dystrophin-deficient DE50-MD canine model harbours a mutation in the major hot spot region for mutations in DMD patients and mimics the preclinical cardiac and skeletal muscle of DMD boys. We performed serial parametric (T1, T2 and extracellular volume) mapping and late gadolinium enhancement (LGE) studies to characterise myocardial pathology in 15-to-36-month-old DE50-MD, (n=8) and wild type (WT, n=6) dogs. In 6/8 DE50-MD dogs left ventricular (LV) subepicardial LGE identified myocardial fibrofatty infiltration, (confirmed with histopathology post-mortem) with the characteristic distribution reported in DMD cardiomyopathy. Parametric mapping techniques exposed diffuse myocardial pathology that was most pronounced in DE50-MD dogs of 30 months and older and supported extracellular matrix expansion due to fibrosis, with or without regional myocardial oedema and /or fatty infiltration in individual dogs. All CMR markers of fibrosis worsened with age in DE50-MD dogs and paralleled deterioration in ventricular function evaluated with conventional and speckle tracking (circumferential strain) echocardiography, the burden of fragmented QRS complexes in 12-lead electrocardiography studies and the severity of pathological lesions. LGE and parametric mapping studies accurately identified a spectrum of myocardial abnormalities encountered in young DE50-MD dogs, further validating the relevance of these dogs as a preclinical model of DMD cardiomyopathy.

pathology↗

bioRxiv2025

The preclinical cardiac phenotype of the DE50-MD dog model of Duchenne muscular dystrophy.

Cardiomyopathy is the leading cause of death in the X-linked disorder, Duchenne Muscular Dystrophy (DMD) yet optimal management strategies remain undetermined. Advances in the search for novel DMD treatments, particularly at cell and molecular levels, rely heavily on the use of translational animal models. It is crucial that these models faithfully recapitulate the human clinical phenotype to best expedite the development of promising treatments. We sought comprehensively to describe the cardiac phenotype of DE50-MD dogs, a novel dystrophin-deficient model that harbours a mutation within the principal DMD mutational hotspot. Cardiac magnetic resonance imaging and echocardiographic studies were performed at approximately 12-week intervals in male, 3- to 18-month-old DE50-MD (n=17) and age-matched littermates, wild type (WT, n=14) dogs. Late gadolinium enhancement (LGE) imaging was performed in a subpopulation of DE50-MD (n=10) and WT (n=11) dogs aged 9 to 18 months. The DE50-MD dogs had smaller left ventricular (LV) mass and LV dimensions than WT dogs. While global ventricular systolic function was preserved, DE50-MD dogs showed early differences in strain and strain rate parameters. Only DE50-MD dogs demonstrated LGE (3/8 dogs studied at 18 months); the subepicardial to transmural, mid-to-basal LV LGE distribution resembling that of DMD patients and of other dystrophic dog models. Histopathological assessment confirmed that LGE corresponded to fibrofatty myocardial scarring, as described in DMD patients and other canine models of dystrophin-deficient cardiomyopathy. The DE50-MD early preclinical cardiac phenotype shares key features of DMD cardiomyopathy prior to onset of global LV systolic dysfunction. Their disproportionately low LV volume to mass supports possible combined physiological hypotrophy and tonic contraction in affected animals.

pathology↗

bioRxiv2025

Bridging Gaps in Antibody Responses and Animal Welfare: Assessing Blood Collection Methods and Vaginal Immunity in Mice Immunized with Intranasal Gonococcal Vaccines

Assessing antibody titers and functional responses is essential for evaluating vaccine efficacy, yet the impact of blood collection methods on these immunological assessments remains unclear. Retro-orbital (RO) blood collection is commonly used but significant complications can occur. Increasingly, investigators have adopted alternative blood collection approaches, such as saphenous vein (SV) sampling to improve laboratory animal welfare. This study compared RO and SV sampling in the development of a Neisseria gonorrhoeae (Ng) vaccine, evaluating Adhesin Complex Protein (ACP) and multiple transferable resistance (Mtr) E protein (MtrE) as antigen candidates. Epitope mapping revealed that ACP and MtrE possess multiple, highly accessible B-cell and T-cell epitope clusters, reinforcing their immunological potential. Following intranasal immunization with rACP, rACP+CpG, and rMtrE+CpG, we assessed the specificity, magnitude, kinetics, and functional quality of immune responses elicited by the immunization regimens. Out of 45 comparisons, only eight significant differences were detected in antibody titers, while the human serum bactericidal assays revealed no differences between RO and SV in antigen-immunized groups. However, antibodies elicited by rACP alone or ACP+CpG in SV samples restored 30.05% and 75.2% of human lysozyme hydrolytic activity compared to 19.3 and 59.9 % in RO, respectively suggesting that SV sampling may be more reliable for assessing functional antibody responses. Beyond its immunological advantages, SV sampling reduces stress, minimizes ocular trauma, and improves animal welfare, making it a viable alternative to RO collection. Given its widespread use in vaccine research, standardizing SV sampling could improve data reliability, ethical compliance, and translational relevance in preclinical studies.

microbiology↗

bioRxiv2018

Clarification and confocal imaging of the non-human primate placental micro-anatomy

Placental function is essential for the development of the fetus, and is - in part - related to the 3D arrangement of the villous and vascular geometry. Recent advances in tissue clarification techniques allow for deep high-resolution imaging with confocal microscopy without altering the spatial characteristics of the tissue. These image stacks can be analyzed quantitatively to provide insights regarding the villous and vascular micro-anatomy as well as the interrelationships between the two. However, such analyses require optimization of the tissue preparation, immuno-labeling, and clarification protocol in order to provide reliable results suitable for the detection of subtle differences in pathologic pregnancies. Placental and fetal development are similar between human and non-human primate pregnancies, with the latter serving as a reliable, validated, highly-controlled, well-characterized translational model for the former.\n\nWe present a protocol for the preparation, immuno-labeling, and clarification of the non-human primate placenta optimized for confocal microscopy and subsequent quantification of the micro-anatomic structures.

pathology↗