Biology subjects

Buchanan, R.

Publications and source records attributed to Buchanan, R..

3 recordsLinked to original sources

bioRxiv2024

Global Prevalence of Cryptosporidium Infections in Cattle and C. parvum genotype distribution: A Meta-Analysis

BackgroundThe protozoan parasite Cryptosporidium is the causative agent of a severe diarrhoeal disease, called cryptosporidiosis. Cryptosporidium species are capable of infecting a wide range of hosts including humans and livestock. In cattle, cryptosporidiosis is now one of the most important causes of neonatal scour globally, either as a sole agent or co-infecting with other pathogens. Cryptosporidiosis is considered globally endemic, with a prevalence of Cryptosporidium in stool samples from 13% to 93% in European cattle. This disease has a significant economic burden, with costs associated with veterinary diagnosis, medication, increased labour, animal rearing and supplemental nutrition as well as being associated with reduced long-term growth rate in calves, causing huge economic losses in livestock industry. Moreover, cattle act as a zoonotic reservoir for Cryptosporidium parvum, a species that is capable of infecting humans as well. As such, monitoring the prevalence of Cryptosporidium in cattle is important due to the public health risk and financial burden the clinical disease causes. MethodsPublications reporting on the prevalence of Cryptosporidium in cattle were collected from PubMed and Google Scholar. Information regarding the species of Cryptosporidium in positive samples, the genotype of C. parvum found in samples, and the diarrhoeic status of the cattle was collected where available. A total of 279 publications were collected for this meta-analysis from six continents and 65 countries to provide an estimation for global bovine Cryptosporidium prevalence. ResultsA 25.5% global prevalence of Cryptosporidium infection was reported, with C. parvum being the most frequently identified species, particularly the IIa subfamily. Diarrhoea was reported in 14,141 cattle samples, of which 36.0% tested positive for Cryptosporidium. Regarding symptoms, we found that in countries reporting over 50% of diarrhoeic positive cattle, C. parvum was the most common species. ConclusionsContinued monitoring and reporting of Cryptosporidium in cattle are crucial for both public health and economic reasons. Consequently, efforts should focus on underreported regions and the development of control measures to reduce prevalence and limit zoonotic transmission.

microbiology↗

bioRxiv2019

The Oscillatory ReConstruction Algorithm (ORCA) adaptively identifies frequency bands to improve spectral decomposition in human and rodent neural recordings

Neural oscillations are routinely analyzed using methods that measure activity in canonical frequency bands (e.g. alpha, 8-12 Hz), though the frequency of neural signals is not fixed and varies within and across individuals based on numerous factors including neuroanatomy, behavioral demands, and species. Further, band-limited activity is an often assumed, typically unmeasured model of neural activity and band definitions vary considerably across studies. These factors together mask individual differences and can lead to noisy spectral estimates and interpretational problems when linking electrophysiology to behavior. We developed the Oscillatory ReConstruction Algorithm ("ORCA"), an unsupervised method to measure the spectral characteristics of neural signals in adaptively identified bands which incorporates two new methods for frequency band identification. ORCA uses the instantaneous power, phase, and frequency of activity in each band to reconstruct the signal and directly quantify spectral decomposition performance using each of four different models. To reduce researcher bias, ORCA provides spectral estimates derived from the best model and requires minimal hyperparameterization. Analyzing human scalp EEG data during eyes open and eyes-closed "resting" conditions, we first identify variability in the frequency content of neural signals across subjects and electrodes. We demonstrate that ORCA significantly improves spectral decomposition compared to conventional methods and captures the well-known increase in low-frequency activity during eyes closure in electrode- and subject-specific frequency bands. We further illustrate the utility of our method in rodent CA1 recordings. ORCA is a novel analytic tool that will allow researchers to investigate how non-stationary neural oscillations vary across behaviors, brain regions, individuals, and species.

neuroscience↗

bioRxiv2019

Differential Effects of Prostaglandin E2 Production and Signaling through the Prostaglandin EP3 Receptor on Human Beta-cell Compensation

ObjectiveSignaling through Prostaglandin E3 Receptor (EP3), a G protein-coupled receptor for E series prostaglandins such as prostaglandin E2 (PGE2), has been linked to the beta-cell dysfunction and loss of beta-cell mass in type 2 diabetes (T2D). In the beta-cell, EP3 is specifically coupled to the unique cAMP-inhibitory G protein, Gz. Divergent effects of EP3 agonists and antagonists or Gz loss on beta-cell function, replication, and survival depending on whether islets are isolated from mice or humans in the lean and healthy, type 1 diabetic, or T2D state suggest a divergence in biological effects downstream of EP3/Gz dependent on the physiological milieu in which the islets reside.\n\nMethodsWe determined the expression of a number of genes in the EP3/Gz signaling pathway; PGE2 production pathway; and the beta-cell metabolic, proliferative, and survival responses to insulin resistance and its corresponding metabolic and inflammatory derangements in a panel of 80 islet preparations from non-diabetic human organ donors spanning a BMI range of approximately 20-45. In a subset of islet preparations, we also performed glucose-stimulated insulin secretion assays with and without the addition of an EP3 agonist, L798,106, and a glucagon-like peptide 1 receptor agonist, exendin-4, allowing us to compare the gene expression profile of each islet preparation with its (1) total islet insulin content (2), functional responses to glucose and incretin hormones, and (3) intrinsic influence of endogenous EP3 signaling in regulating these functional responses. We also transduced two independent islet preparations from three human organ donors with adenoviruses encoding human Gz or a GFP control in order to determine the impact of Gz hyperactivity (a mimic of the T2D state) on human islet insulin content and functional response to glucose.\n\nResultsIn contrast to results from islets isolated from T2D mice and human organ donors, where PGE2-mediated EP3 signaling actively contributes to beta-cell dysfunction, PGE2 production and EP3 expression appeared positively associated with various measurements of functional beta-cell compensation. While Gz mRNA expression was negatively associated with islet insulin content, that of each of the Gz-sensitive adenylate cyclase (AC) isoforms were positively associated with BMI and cyclin A1 mRNA expression, suggesting increased expression of AC1, AC5, and AC6 is a compensatory mechanism to augment beta-cell mass. Human islets over-expressing Gz via adenoviral transduction had reduced islet insulin content and secretion of insulin in response to stimulatory glucose as a percent of content, consistent with the effects of hyperactivation of Gz by PGE2/EP3 signaling observed in islets exposed to the T2D physiological milieu.\n\nConclusionsOur work sheds light on critical mechanisms in the human beta-cell compensatory response, before the progression to frank T2D.

molecular biology↗