Publications by authors named "Michael J Stack"

Introduction: Whole blood (WB) transfusion is increasingly used in the civilian trauma population compared to standard component therapy (CT). Prior prospective observational and retrospective studies have shown a mortality benefit. We aim to assess statewide clinical outcomes associated with WB use in an adult trauma population.

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Introduction: Necrotizing enterocolitis (NEC) represents a severe gastrointestinal condition predominantly affecting premature neonates, often requiring surgical intervention involving ostomy or stoma formation. Our study aims to evaluate the outcomes associated with different timing and weights at stoma closure following surgery for NEC in infants.

Materials And Methods: We conducted a retrospective review of premature infants with NEC at a tertiary children's hospital from 2011 to 2022.

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Background And Objectives: Many cancers in young adulthood differ in terms of biology, histologic variation, and prognosis compared to cancer in other older age groups. Differences in cutaneous melanoma among young adults compared to other older age groups, as well as between sexes in young adults are not well studied.

Methods: The National Cancer Database was queried for patients diagnosed with cutaneous melanoma between 2004 and 2017.

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Background: Early detection and standardized treatment are crucial for enhancing outcomes for patients with cutaneous melanoma, the commonly diagnosed skin cancer. However, access to quality health care services remains a critical barrier for many patients, particularly the uninsured. Whereas Medicaid expansion (ME) has had a positive impact on some cancers, its specific influence on cutaneous melanoma remains understudied.

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Background: The infectious agent responsible for the bovine spongiform encephalopathy (BSE) epidemic in Great Britain is a transmissible spongiform encephalopathy (TSE) strain with uniform properties but the origin of this strain remains unknown. Based on the hypothesis that classical BSE may have been caused by a TSE strain present in sheep, cattle were inoculated intracerebrally with two different pools of brains from scrapie-affected sheep sourced prior to and during the BSE epidemic to investigate resulting disease phenotypes and characterise their causal agents by transmission to rodents.

Results: As reported in 2006, intracerebral inoculation of cattle with pre-1975 and post-1990 scrapie brain pools produced two distinct disease phenotypes, which were unlike classical BSE.

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Background: Atypical bovine spongiform encephalopathies (BSEs), classified as H-type and L-type BSE based on the Western immunoblot profiles, are naturally occurring diseases in cattle, which are phenotypically different to classical BSE. Transmission studies in cattle using the intracerebral route resulted in disease where the phenotypes were maintained irrespective of BSE type but clinically affected cattle with a shorter survival time displayed a nervous form whereas cattle with a longer survival time displayed a dull form. A second transmission study is reported here where four cattle were intracerebrally inoculated with brain tissue from experimentally infected cattle presenting with either the nervous or dull form of H- or L-type BSE to determine whether the phenotype is maintained.

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Article Synopsis
  • Development of transgenic mouse models with a chimeric murine/ovine prion protein (PrP) allows researchers to study the susceptibility of these mice to ruminant prion diseases.
  • The newly created Tg(Mu/OvPrP(AHQ))EM16 mice show high susceptibility to various prions, achieving 100% disease penetrance and rapid disease progression compared to wild-type mice.
  • The study confirms that these EM16 mice are effective for differentiating ruminant prions and detecting atypical scrapie infectivity through various diagnostic methods.
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Background: To provide information on dose-response and aid in modelling the exposure dynamics of the BSE epidemic in the United Kingdom groups of cattle were exposed orally to a range of different doses of brainstem homogenate of known infectious titre from clinical cases of classical bovine spongiform encephalopathy (BSE). Interim data from this study was published in 2007. This communication documents additional BSE cases, which occurred subsequently, examines possible influence of the bovine prion protein gene on disease incidence and revises estimates of effective oral exposure.

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Background: The majority of atypical bovine spongiform encephalopathy (BSE) cases so far identified worldwide have been detected by active surveillance. Consequently the volume and quality of material available for detailed characterisation is very limiting. Here we report on a small transmission study of both atypical forms, H- and L-type BSE, in cattle to provide tissue for test evaluation and research, and to generate clinical, molecular and pathological data in a standardised way to enable more robust comparison of the two variants with particular reference to those aspects most relevant to case ascertainment and confirmatory diagnosis within existing regulated surveillance programmes.

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Background: Transmission of the prion disease bovine spongiform encephalopathy (BSE) occurred accidentally to cattle and several other mammalian species via feed supplemented with meat and bone meal contaminated with infected bovine tissue. Prior to United Kingdom controls in 1996 on the feeding of mammalian meat and bone meal to farmed animals, the domestic chicken was potentially exposed to feed contaminated with the causal agent of BSE. Although confirmed prion diseases are unrecorded in avian species a study was undertaken to transmit BSE to the domestic chicken by parenteral and oral inoculations.

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Prions are largely contained within the nervous and lymphoid tissue of transmissible spongiform encephalopathy (TSE) infected animals. However, following advances in diagnostic sensitivity, PrP(Sc), a marker for prion disease, can now be located in a wide range of viscera and body fluids including muscle, saliva, blood, urine and milk, raising concerns that exposure to these materials could contribute to the spread of disease in humans and animals. Previously we demonstrated low levels of infectivity in the liver of sheep experimentally challenged with bovine spongiform encephalopathy.

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Background: Various clinical protocols have been developed to aid in the clinical diagnosis of classical bovine spongiform encephalopathy (BSE), which is confirmed by postmortem examinations based on vacuolation and accumulation of disease-associated prion protein (PrPd) in the brain. The present study investigated the occurrence and progression of sixty selected clinical signs and behaviour combinations in 513 experimentally exposed cattle subsequently categorised postmortem as confirmed or unconfirmed BSE cases. Appropriate undosed or saline inoculated controls were examined similarly and the data analysed to explore the possible occurrence of BSE-specific clinical expression in animals unconfirmed by postmortem examinations.

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Background: The cause of the bovine spongiform encephalopathy (BSE) epidemic in the United Kingdom (UK) was the inclusion of contaminated meat and bone meal in the protein rations fed to cattle. Those rations were not restricted to cattle but were also fed to other livestock including farmed and free living deer. Although there are no reported cases to date of natural BSE in European deer, BSE has been shown to be naturally or experimentally transmissible to a wide range of different ungulate species.

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The squirrel poxvirus (SQPV) is the probable mediator of apparent competition between the introduced invading gray squirrel (Sciurus carolinensis) and the red squirrel (Sciurus vulgaris) in the UK, and modeling studies have shown that this viral disease has had a significant impact on the decline of the red squirrel in the UK. However, given our limited understanding of the epidemiology of the disease, and more generally the effects of invasive species on parasite ecology, there is a need to investigate the transmission dynamics and the relative pathogenicity of the virus between species. We aimed to increase our knowledge of these processes through an empirical study in which we: (i) used pathological signs and transmission electron microscopy (TEM) to diagnose SQPV disease in red squirrels found dead during scanning surveillance between 1993 and 2005; (ii) detected antibody to SQPV using an enzyme-linked immunosorbent assay (ELISA) in the same animals; and (iii) mapped cases of the disease, and the gray squirrel distribution, using a geographical information system.

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Background: Given the theoretical proposal that bovine spongiform encephalopathy (BSE) could have originated from sheep scrapie, this study investigated the pathogenicity for cattle, by intracerebral (i.c.) inoculation, of two pools of scrapie agents sourced in Great Britain before and during the BSE epidemic.

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Article Synopsis
  • Transmissible spongiform encephalopathies (TSEs) include diseases like BSE and scrapie, diagnosed through characteristic lesions or by detecting abnormal prion proteins in tissues.
  • Correct tissue sampling is vital for accurate test sensitivity, with rapid tests mostly using ELISA or Western blotting for initial detection.
  • Confirmatory testing involves histology, immunohistochemistry, and advanced methods like electron microscopy, while definitive strain characterization often relies on specialized bioassays using transgenic mice.
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Brain tissue from a case of bovine spongiform encephalopathy (BSE) from Alberta was subjected to a Western immunoblotting technique to ascertain the molecular profile of any disease-specific, abnormal prion protein, that is, prion protein that is protease-resistant (PrP(res)). This technique can discriminate between isolates from BSE, ovine scrapie, and sheep experimentally infected with BSE. Isolates of brain tissue from the BSE case in Alberta, 3 farmed elk with chronic wasting disease (CWD) from different parts of Saskatchewan, and 1 farmed white-tailed deer with CWD from Edmonton, Alberta, were examined alongside isolates of brain tissue from BSE, ovine scrapie, and sheep experimentally infected with BSE from the United Kingdom (UK).

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Article Synopsis
  • A study analyzed brain tissues from ruminants using Western immunoblotting and two monoclonal antibodies to identify differences in prion protein (PrP) glycoforms associated with ovine scrapie and BSE.
  • Findings revealed specific distinctions in the molecular weight of PrP forms, particularly noting that the unglycosylated protein band from ovine scrapie had a higher molecular weight compared to those from BSE-infected sheep and cattle.
  • This method effectively differentiated between experimentally inoculated and natural scrapie cases, but struggled to differentiate between natural BSE-infected cattle and ovine scrapie, indicating potential limitations in the antibody effectiveness and the complexities of prion strain identification.
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