Ahmad Al-Dissi

University of Saskatchewan | U of S · Department of Veterinary Pathology

Ergot alkaloids are secondary metabolites that are produced by fungi and contaminate cereal crops and grasses. The ergot alkaloids produced by Claviceps purpurea are the most abundant worldwide. The metabolites exist in two configurations, the C-8-R-isomer (R-epimer) and the C-8-S-isomer (S-epimer). These two configurations can interconvert to one...

Ergot sclerotia produce toxic secondary metabolites, ergot alkaloids, that infect cereal crops and grasses. Ergot alkaloids have two isomeric configurations: the C-8-R-isomer (R-epimer), and the C-8-S-isomer (S-epimer). Ergot contaminated matrices, such as cereal grains or grasses, may be stored for extended periods at various temperatures before b...

The present study aimed to examine the effects of environmentally relevant concentrations of cadmium (Cd) and Benzo[a]Pyrene (BaP) in the adult zebrafish (Danio rerio). To this end, fish were exposed to either 1 or 10 μg/L Cd or 0.1 or 1 μg/L BaP in isolation, or a co-exposure containing a mixture of the two toxicants. Our results showed extensive...

Ergot alkaloids are secondary metabolites that exist in two configurations, the C-8-R-isomer (R-epimer), and the C-8-S-isomer (S-epimer). Toxic effects of ergot, such as vasoconstriction, have been primarily attributed to the R-epimer bioactivity, as compared to the S-epimer. Recent studies demonstrated potential bioactivity of S-epimers. Therefore...

E-cadherin is an adhesion molecule expressed on epithelial surfaces. Loss of its expression is described in cancerous tissues. Here, we examined the expression of E-cadherin in canine cutaneous squamous cell carcinoma (SCC) and determined its association with tumor grade (TG), proliferation index (PI), apoptosis index (AI), and intra-tumoral microv...

Complex mixtures of unknown contaminants present a challenge to identify toxicological risks without using large numbers of animals and labor-intensive screens of all organs. This study examined soil extracts from a legacy-contaminated pesticide packaging and blending site. HepG2 cytotoxicity was used as an initial screen of 18 soil samples; then,...

The liver is the main storage site for copper. Excess copper accumulation, however, is a risk factor for the development of chronic hepatitis in dogs. Mass spectrometry or rhodanine staining are frequently used methods to assess copper levels in the liver. The association was studied between analytic hepatic copper levels and rhodanine scores in ar...

Complex mixtures of unknown contaminants present a challenge to identify toxicological risks without using large numbers of animals and labour-intensive screens of all organs. This study examined soil extracts from a legacy contaminated pesticide packaging and blending site. HepG2 cytotoxicity was used as an initial screen of 18 soil samples to ide...

Detoxification of ergot-contaminated feed by ammonia would be a practical application, given that ammonia is routinely used in the agriculture industry. To assess the effects of ammonia on ergot alkaloids, natural ergot-contaminated wheat was ammoniated. The total concentration of ergot alkaloids (R- and S-epimers) decreased after exposure to ammon...

Vasoconstriction is a known effect associated with ergot alkaloid consumption. The vascular contractile responses are often sustained for an extended period after exposure. Ergot alkaloids exist in two molecular configurations, the C-8-(R)-isomer (R-epimer) and the C-8-(S)-isomer (S-epimer). The sustained vascular contractile response to the R-epim...

The objective of this study was to evaluate the pharmacokinetics profile of ergot alkaloids when administered to sheep orally. Although ergot alkaloids frequently contaminate animal feed, current understanding of their pharmacokinetics in animals cannot adequately predict toxicity. Blood samples were collected from ewes at 0.5, 1, 3, 5, and 12 h af...

Ergot sclerotia effect cereal crops intended for consumption. Ergot alkaloids within ergot sclerotia are assessed to ensure contamination is below safety standards established for human and animal health. Ergot alkaloids exist in two configurations, the R and S-epimers. It is important to quantify both configurations. The objective of this study wa...

Ergotism is a common and increasing problem in Saskatchewan’s livestock. Chronic exposure to low concentrations of ergot alkaloids is known to cause severe arterial vasoconstriction and gangrene through the activation of adrenergic and serotonergic receptors on vascular smooth muscles. The acute vascular effects of a single oral dose with high-leve...

Purpose The purpose of this study was to evaluate the efficacy and toxicity of a novel lanthanum compound, La(XT), in an ovariectomized (OVX) rat model of osteoporosis. Methods Twenty-four ovariectomized female Sprague Dawley rats were divided into 3 groups receiving a research diet with/without treatment compounds (alendronate: 3 mg/kg; La(XT) 10...

Chronic cholangiohepatitis (CCH) is a common pathological condition in cats with a guarded prognosis and unknown etiology. Recently, in human medicine, there has been increased interest in enhancing liver defense mechanisms as an effective treatment strategy to control liver diseases that have a poor prognosis. Metallothionein (MT) is a ubiquitous...

Ergot alkaloids are produced by the fungus Claviceps purpurea and their levels are carefully monitored in animal and human diets due to their harmful effects and widespread contamination of cereal crops. Ergot alkaloids exist in two forms known as the (R) and (S)-epimer with only the former being monitored in diets in North America. The (S)-epimers...

A 19-week-old neutered male domestic shorthair cat was examined because of multiple raised pruritic skin lesions along the dorsal head and back. Histopathology of biopsies of the lesions detected nodular pyogranulomatous dermatitis with vasculitis and necrosis, leading to a suspicion of feline infectious peritonitis (FIP). Postmortem examination re...

Chronic liver disease is an important cause of illness in horses, and treatment is mainly supportive. Research into new treatment modalities for humans has shown promising data regarding metallothionein (MT), which has been shown to possess regenerative, antifibrotic, and anti-inflammatory properties. This study aimed to examine the relationship be...

Acute selenium toxicosis occurred in 3-week-old lambs after accidental over-supplementation by intramuscular injection and caused dyspnea, cyanosis, and sudden death. Pathological lesions included myocardial necrosis, skeletal muscle necrosis, pulmonary edema, hydrothorax, and hydropericardium.

A 6-year-old castrated male boxer dog with right-sided dark purulent nasal discharge and acute bilateral blindness was diagnosed on magnetic resonance imaging (MRI) and then on necropsy with primary nasal malignant melanoma that extended into the brain, as well as concurrent ocular melanosis. There was no evidence of metastasis in other organs.

The pathogenesis of fetal death associated with porcine reproductive and respiratory syndrome (PRRS) is hypothesized to be a consequence of PRRS virus-induced apoptosis at the maternal-fetal interface (MFI). The objectives of this study were to evaluate distribution and degree of apoptosis in the uterine and fetal placental tissues during the exper...

Results of Generalized Estimating Equations (GEE). GEE confirmed the association between numbers of TUNEL positive cells/mm2 at maternal fetal interface (MFI) and the odds of a meconium stained fetus (versus viable). (DOCX)

Several routes of porcine reproductive and respiratory virus PRRSV transmission across the porcine diffuse epitheliochorial placentation have been proposed, but none have been proven. The objectives of this study were to investigate associations between numbers of CD163 and CD169 positive macrophages, cathepsin positive areolae, and type 2 PRRSV lo...

Although dogs with acute necrotizing pancreatitis (ANP) can develop respiratory complications, there are no data describing lung injury in clinical cases of ANP in dogs. Therefore, we conducted a study to characterize lung injury and determine if pulmonary intravascular macrophages (PIMs) are induced in dogs with ANP (n = 21) compared with control...

The pathogenesis of fetal death caused by porcine reproductive and respiratory syndrome virus (PRRSV) remains unclear. The objective of this study was to improve our understanding of the pathogenesis by assessing potential relationships between specific histopathological lesions and PRRSV RNA concentration in the fetuses and the maternal-fetal inte...

Proportion of litter tested PRRSV qRT-PCR positive. Frequency distribution of the percentages of fetuses within litters that tested positive for PRRSV using qRT-PCR at 21 days post-inoculation at gestation day 85 in PRRSV infected pregnant gilts. (TIF)

Proportion of maternal-fetal interface samples tested PRRSV qRT-PCR positive. Frequency distribution of the within litter percentages of maternal-fetal interface samples corresponding to each fetus that tested positive for PRRSV using qRT-PCR at 21 days post-inoculation at gestation day 85 in PRRSV infected pregnant gilts. (TIF)

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The chronic form of primary hepatitis occurs commonly in dogs, and the etiology is rarely found. Metallothionein (MT) is a heavy metal-binding protein found in many organs, including the liver. MT was recently shown to enhance liver regeneration and decrease hepatic fibrosis in human beings. This study examined the expression of MT in 24 cases of c...

A wide variety of toxins cause diseases in the horse and are investigated routinely by veterinarians and veterinary pathologists to identify the cause of illness and death. A complete investigation involves performing a thorough necropsy and requires macroscopic and microscopic examination of lesions and a variety of laboratory testing to obtain an...

Mannheimia haemolytica is an important cause of pneumonia in feedlot cattle. Nuclear factor erythroid-2-related factor 2 (Nrf2) is a redox-sensitive transcription factor responsible for the induction of antioxidant enzymes, such as heme oxygenase 1 (HO-1), within the lung. The expression of Nrf2 and HO-1 was immunohistochemically evaluated in 4 cal...

There is evidence that dogs suffering from acute necrotizing pancreatitis (ANP) can develop respiratory disease. However, there are no data describing the lung histopathology in clinical cases of ANP in dogs. Therefore, we hypothesized that lungs of dogs that died due to ANP (n=21) will be inflamed along with recruitment of PIMs, a pro‐inflammatory...

Blood supply is essential for development and growth of tumors and angiogenesis is the fundamental process of new blood vessel formation from preexisting ones. Angiogenesis is a prognostic indicator for a variety of tumors, and it coincides with increased shedding of neoplastic cells into the circulation and metastasis. Several molecules such as ce...

Secondhand smoke (SHS) impairs cardiac function and resveratrol is cardioprotective, possibly via antioxidant and anti-inflammatory capabilities. Previously, it was shown that resveratrol protects against SHS-induced cardiac dysfunction, but the molecular mechanism is not clear. We measured cardiac function in pigs exposed to SHS alone in a first e...

The mechanisms by which environmental tobacco smoke (ETS) causes adverse cardiovascular effects remain unclear. Resveratrol is a natural polyphenol from red wine which may be beneficial to the cardiovascular system. Therefore, the ability of daily oral resveratrol (5mg/kg) to prevent adverse effects of a 14-day ETS exposure (1 h/day) on endothelial...

The aim of this study was to determine if carbon monoxide (CO) is responsible for acute adverse cardiovascular effects of different sources of smoke: second-hand tobacco smoke (SHS), incense and candle smoke. Endothelial function was tested using flow-mediated dilation (FMD) in pigs and was shown to be sensitive to nitric oxide synthase blockade. S...

An 11-year-old domestic short hair cat with dyspnea, cyanosis, and pleural effusion died. Necropsy revealed several nodules and masses on the parietal pleura, pericardium, and diaphragm. The tumor contained epithelial and mesenchymal components and displayed osseous and chondromatous differentiation. Tumors cells were positive for pancytokeratin an...

Chronic selenium (Se) toxicosis was found in a herd of white-tailed deer showing signs of anorexia, weight loss, and lameness. Concentration of Se in the liver ranged from 2.7 to 8.97 mg/kg wet weight. Myocardial necrosis, mineralization, and fibroplasia were seen histologically. This is the first report of this toxicosis in white-tailed deer.

The expression of 5 markers associated with angiogenesis, proliferation, and apoptosis was studied in 26 canine simple mammary gland adenocarcinomas (SMGAs). The adenocarcinomas were graded histologically, and tissue sections were immunohistochemically stained for the expression of vascular endothelial growth factor (VEGF), VEGF receptor-2 (VEGFR-2...

The expression of five markers associated with tumour angiogenesis, proliferation and apoptosis was studied in 24 canine cutaneous fibrosarcomas. Tumours were assigned histological grades and were immunohistochemically evaluated for the expression of vascular endothelial growth factor (VEGF) and vascular endothelial growth factor receptor-2 (VEGFR-...

The expression of 5 markers associated with angiogenesis was studied in canine squamous cell carcinomas (SCCs) (n = 19) and canine trichoepitheliomas (TCPs) (n = 24). SCCs were assigned histologic grades, and tissue sections from both tumor types were immunohistochemially stained for the expression of vascular endothelial growth factor (VEGF), vasc...