Junctional epithelia are common sites for pathological transformations. In mice, the stratified e... more Junctional epithelia are common sites for pathological transformations. In mice, the stratified epithelium of the forestomach joins the simple glandular epithelium of the cardia at the limiting ridge. We previously demonstrated the expression of vitamin A receptors in the gastric stem/progenitor cells and their progeny and found that excess retinoic acid enhances cellular dynamics of gastric epithelium. This study examines how deficiency of vitamin A would alter gastric epithelial stem cell lineages. Three-week-old mice of both genders were weaned and fed with a vitamin A deficient (VAD) diet for 4 or 8 months. Sex- and weight-matched littermate mice received a standard (control) diet. To label S-phase cells, all mice received a single intraperitoneal injection of 5-bromo-2-deoxyuridine before being euthanized. Stomach tissues were processed for microscopic examination and protein analysis to investigate stem cell lineages using different stains, lectins, or antibodies. The Student’...
Helicobacter pylori infection of the human stomach is associated with altered acid secretion, los... more Helicobacter pylori infection of the human stomach is associated with altered acid secretion, loss of acid-producing parietal cells, and, in some hosts, adenocarcinoma. We have used a transgenic mouse model to study the effects of parietal cell ablation on H. pylori pathogenesis. Ablation results in amplification of the presumptive gastric epithelial stem cell and its immediate committed daughters. The amplified
Probiotics are used in the management of some gastrointestinal diseases. However, little is known... more Probiotics are used in the management of some gastrointestinal diseases. However, little is known about their effects on normal gastric epithelial biology. The aim of this study was to explore how the probiotic mixture VSL#3 affects gastric cell lineages in mice with a special focus on protective and aggressive factors. Weight-matching littermate male mice (n = 14) were divided into treated and control pairs. The treated mice received VSL#3 (5 mg/day/mouse) by gastric gavage for 10 days. Control mice received only the vehicle. Food consumption and bodyweight were monitored. All mice were injected intraperitoneally with bromodeoxyuridine (120 mg/Kg bodyweight) two hours before sacrificed to label S-phase cells. Stomach tissues were processed for lectin- and immunohistochemical examination. ImageJ software was used to quantify immunolabeled gastric epithelial cells. Real-time quantitative polymerase chain reaction was used to provide relative changes in expression of gastric cell line...
Stem cells have attracted many scientists because of their unique properties and therapeutic appl... more Stem cells have attracted many scientists because of their unique properties and therapeutic applications. However, very little is known on the environmental toxins that could affect their biological features. This study focuses on the consequences of the exposure of a cell line representative of the mouse gastric stem/progenitor (mGS) cells to diesel exhaust particles (DEPs). These immortal cells were cultured using routine protocols. The DEPs were added to the culture media at 1, 10, and 100 µg/mL for 1 to 72 h. The cells were assayed for their viability, migration, oxidative stress, and the expression of genes specific for cell proliferation, pluripotency, and death. DEPs induced a reduction in the metabolic activity of mGS cells, only at a high concentration of 100 µg/mL. However, no significant effects were detected on cell migration, oxidative stress markers (glutathione and thiobarbituric acid reactive substances), and cell death related proteins/genes. Interestingly, these f...
γ-Adaptin and clathrin heavy chain were identified on tubulovesicles of gastric oxyntic cells wit... more γ-Adaptin and clathrin heavy chain were identified on tubulovesicles of gastric oxyntic cells with the anti-γ-adaptin monoclonal antibody (MAb) 100/3 and an anti-clathrin heavy chain MAb (MAb 23), respectively. In Western blots, crude gastric microsomes from rabbit and rat and density gradient-purified, H-K-ATPase-rich microsomes from these same species were immunoreactive for γ-adaptin and clathrin. In immunofluorescent labeling of isolated rabbit gastric glands, anti-γ-adaptin and anti-clathrin heavy chain immunoreactivity appeared to be concentrated in oxyntic cells. In primary cultures of rabbit oxyntic cells, the immunocytochemical distribution of γ-adaptin immunoreactivity was similar to that of the tubulovesicular membrane marker in oxyntic cells, the H-K-ATPase. Further biochemical characterization of the tubulovesicular γ-adaptin-containing complex suggested that it has a subunit composition that is typical of that for a clathrin adaptor: in addition to the γ-adaptin subuni...
In the gastrointestinal (GI) epithelium, cellular differentiation occurs in five stages: stem cel... more In the gastrointestinal (GI) epithelium, cellular differentiation occurs in five stages: stem cells, precursor cells, transit cells, mature cells, and terminal cells. Stem cells are the least differentiated and have the greatest proliferation potential. In the stomach, they are located in the isthmus region of the pit-gland unit and give rise to four main cell lineages through precursor-amplifying cells: pre-pit cells give rise to mucous-secreting pit cells that migrate and reach the gastric luminal surface in 3 d; pre-neck cells differentiate into neck cells that migrate toward the bottom of the gland while changing their phenotype into the longest lived cells in the unit, zymogenic cells; pre-parietal cells complete their differentiation in the isthmus and then undergo bipolar migration to the pit and the base of the gland, where they have a life-span of about 2 mo. The precursors of enteroendocrine cells also originate in the isthmus and follow the bipolar mode of migration. In the small intestine, stem cells are located in the fourth cell layer from the crypt bottom and are derived from a single preceding cell (clonal). An adult mouse has about 1.1 million crypts and each crypt contains about 250 cells, of which about two-thirds go through the cell cycle every 12 h; each crypt produces about 13–16 new cells per hour! They give rise to four main cell lineages: absorptive, goblet, enteroendocrine, and Paneth. While members of the former three lineages differentiate while migrating upward along the crypt-villus axis, those of the latter complete their differentiation and remain at the crypt bottom. M-cell precursors are found in the intestinal crypts around lymphoid follicles and their mature forms migrate to cover the dome-shaped Peyer’s patches. In the colon, the lineages are columnar cells (80%), goblet cells (16%), deep crypt secretory cells (3%), and enteroendocrine cells (0.4%). Precursors of caveolated cells are also produced by stem cells throughout the GI tract.
Endoscopic biopsies of the upper gastrointestinal tract account for a significant amount of workl... more Endoscopic biopsies of the upper gastrointestinal tract account for a significant amount of workload for general and specialist histopathologists. The most common indications for gastric biopsy include diagnosis of various types of gastritis, peptic ulcer disease, confirmation of the presence of Helicobacter pylori, and neoplastic lesions. Histological recognition of subtle gastric mucosal infiltration by diffuse-type (signetring) adenocarcinoma is a well-recognized area of diagnostic difficulty. We present two examples of marked cytoplasmic vacuolation of parietal cells mimicking signet ring cell carcinoma.
Simple Summary The gastric epithelium comprises multiple cell types that undergo continuous renew... more Simple Summary The gastric epithelium comprises multiple cell types that undergo continuous renewal through controlled proliferation, differentiation and death. Several vitamins, such as vitamin D (VD), are known to contribute to tissue homeostasis and numerous studies have shown the importance of VD in different body organ systems. However, VD’s normal function in the stomach is understudied. To better understand the role of VD in the murine stomach, we initially confirmed the expression of VD receptors (VDR) in the stomach. Mice were fed a VD-deficient diet for 3 months. The results showed that the proton pump of acid-secreting parietal cells was downregulated in vitamin D-deficient mice and contributed to an abnormal gastric physiology. Moreover, this diet increased the gastrin hormone gene expression and increased gastric epithelial cell proliferation. These findings suggest essential biological roles for VDR and VD in gastric epithelial homeostasis. Future research will be requ...
Simple Summary The wall of the stomach is easily damaged by different factors leading to serious ... more Simple Summary The wall of the stomach is easily damaged by different factors leading to serious diseases such as ulcers and cancer. In this study, the effects of a mixture of different types of beneficial bacteria (De Simone Formulation) were investigated in a mouse model of stomach wall damages induced by single or multiple doses of acetylsalicylic acid. Control mice received water. The stomachs of all mice were processed for microscopic examination and labeling of dividing stem cells and stomach cell lineages secreting mucus, acid, pepsin, and hormones. The results reveal beneficial effects for the multiple bacterial strain of De Simone Formulation given before or after the induction of stomach erosions. The regeneration of the stomach wall was associated with an increase in stem cell proliferation and enhanced production of protective factors such as mucus, and restoration of the aggressive factors produced by acid and pepsin secreting cell lineages. Therefore, the protective an...
Biodegradable scaffolds are useful tools in the field of tissue engineering and regenerative medi... more Biodegradable scaffolds are useful tools in the field of tissue engineering and regenerative medicine. The aim of this study was to test the potential of the human stem cells of apical papilla (SCAP) to attach, proliferate and differentiate on a polycaprolactone (PCL)-based scaffolds. SCAP were extracted from the root apical papillae of freshly extracted immature premolar teeth by using enzymatic digestion. Porous PCL scaffolds were fabricated using particle leaching method and NaCl or mannitol as porogens. SCAP of passage 3 were seeded on non-porous and porous PCL scaffolds for up to 14 days. For control, cells were cultured on glass coverslips. Picogreen DNA quantification was used to assay for cell proliferation. Cell differentiation and development of calcification nodules were examined using scanning electron microscopy and alizarin red staining. SCAP showed a comparable attachment, growth and proliferation patterns on PCL scaffolds and coverslips. Cell proliferation was enhanced on mannitol scaffolds at all time points. Calcification nodules were detected in all PCL scaffolds while it was not present on glass coverslips. These nodules were detected on NaCl-scaffolds by day 7 and on mannitol and non-porous scaffolds by day 14. In conclusion, SCAP were able to attach, proliferate and differentiate on PCL scaffolds without using any inductive media, indicating their potential application for dental tissue regeneration.
Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry, and pharmacology, Jan 11, 2018
Breast cancer is the most common cancer in women worldwide, and within this cancer type, triple-n... more Breast cancer is the most common cancer in women worldwide, and within this cancer type, triple-negative breast cancers have the worst prognosis. The identification of new genes associated with triple-negative breast cancer progression is crucial for developing more specific anti-cancer targeted therapies, which could lead to a better management of these patients. In this context, we have recently demonstrated that SMARCAD1, a DEAD/H box-containing helicase, is involved in breast cancer cell migration, invasion, and metastasis. The aim of this study was to investigate the impact of the stable knockdown of SMARCAD1 on human breast cancer cell progression. Using two different designs of shRNA targeting SMARCAD1, we investigated the impact of the stable knockdown of SMARCAD1 on human breast cancer cell proliferation and colony growth in vitro and on tumour growth in chick embryo and nude mouse xenograft models in vivo using MDA-MB-231 (ER-/PR-/ HER2-) and T47D (ER+/PR+/-/HER2-) human b...
Breast cancer is the most common type of cancer and the leading cause of cancer-related deaths am... more Breast cancer is the most common type of cancer and the leading cause of cancer-related deaths among women in the United Arab Emirates and worldwide. Although many factors contribute to the high incidence of breast cancer, a considerable number of cases are related to environmental factors. In the present study, breast cancer was induced in female rats using a single dose, 80 mg/kg body wt, of the environmental carcinogen 7,12-dimethylbenz[a]anthracene (DMBA). The aim of the present study, was to characterize some of the molecular changes that occur during breast cancer development in the DMBA-treated rat model. Mammary gland tissues of control and DMBA-treated rats were processed for: i) immunohistochemical probing using anti-BRCA1 antibody to characterize and correlate the localization of this cell cycle protein during progression to cancer, ii) western blotting to analyze the alteration of p53 protein expression in preneoplastic and neoplastic lesions of the mammary glands, and i...
Junctional epithelia are common sites for pathological transformations. In mice, the stratified e... more Junctional epithelia are common sites for pathological transformations. In mice, the stratified epithelium of the forestomach joins the simple glandular epithelium of the cardia at the limiting ridge. We previously demonstrated the expression of vitamin A receptors in the gastric stem/progenitor cells and their progeny and found that excess retinoic acid enhances cellular dynamics of gastric epithelium. This study examines how deficiency of vitamin A would alter gastric epithelial stem cell lineages. Three-week-old mice of both genders were weaned and fed with a vitamin A deficient (VAD) diet for 4 or 8 months. Sex- and weight-matched littermate mice received a standard (control) diet. To label S-phase cells, all mice received a single intraperitoneal injection of 5-bromo-2-deoxyuridine before being euthanized. Stomach tissues were processed for microscopic examination and protein analysis to investigate stem cell lineages using different stains, lectins, or antibodies. The Student’...
Helicobacter pylori infection of the human stomach is associated with altered acid secretion, los... more Helicobacter pylori infection of the human stomach is associated with altered acid secretion, loss of acid-producing parietal cells, and, in some hosts, adenocarcinoma. We have used a transgenic mouse model to study the effects of parietal cell ablation on H. pylori pathogenesis. Ablation results in amplification of the presumptive gastric epithelial stem cell and its immediate committed daughters. The amplified
Probiotics are used in the management of some gastrointestinal diseases. However, little is known... more Probiotics are used in the management of some gastrointestinal diseases. However, little is known about their effects on normal gastric epithelial biology. The aim of this study was to explore how the probiotic mixture VSL#3 affects gastric cell lineages in mice with a special focus on protective and aggressive factors. Weight-matching littermate male mice (n = 14) were divided into treated and control pairs. The treated mice received VSL#3 (5 mg/day/mouse) by gastric gavage for 10 days. Control mice received only the vehicle. Food consumption and bodyweight were monitored. All mice were injected intraperitoneally with bromodeoxyuridine (120 mg/Kg bodyweight) two hours before sacrificed to label S-phase cells. Stomach tissues were processed for lectin- and immunohistochemical examination. ImageJ software was used to quantify immunolabeled gastric epithelial cells. Real-time quantitative polymerase chain reaction was used to provide relative changes in expression of gastric cell line...
Stem cells have attracted many scientists because of their unique properties and therapeutic appl... more Stem cells have attracted many scientists because of their unique properties and therapeutic applications. However, very little is known on the environmental toxins that could affect their biological features. This study focuses on the consequences of the exposure of a cell line representative of the mouse gastric stem/progenitor (mGS) cells to diesel exhaust particles (DEPs). These immortal cells were cultured using routine protocols. The DEPs were added to the culture media at 1, 10, and 100 µg/mL for 1 to 72 h. The cells were assayed for their viability, migration, oxidative stress, and the expression of genes specific for cell proliferation, pluripotency, and death. DEPs induced a reduction in the metabolic activity of mGS cells, only at a high concentration of 100 µg/mL. However, no significant effects were detected on cell migration, oxidative stress markers (glutathione and thiobarbituric acid reactive substances), and cell death related proteins/genes. Interestingly, these f...
γ-Adaptin and clathrin heavy chain were identified on tubulovesicles of gastric oxyntic cells wit... more γ-Adaptin and clathrin heavy chain were identified on tubulovesicles of gastric oxyntic cells with the anti-γ-adaptin monoclonal antibody (MAb) 100/3 and an anti-clathrin heavy chain MAb (MAb 23), respectively. In Western blots, crude gastric microsomes from rabbit and rat and density gradient-purified, H-K-ATPase-rich microsomes from these same species were immunoreactive for γ-adaptin and clathrin. In immunofluorescent labeling of isolated rabbit gastric glands, anti-γ-adaptin and anti-clathrin heavy chain immunoreactivity appeared to be concentrated in oxyntic cells. In primary cultures of rabbit oxyntic cells, the immunocytochemical distribution of γ-adaptin immunoreactivity was similar to that of the tubulovesicular membrane marker in oxyntic cells, the H-K-ATPase. Further biochemical characterization of the tubulovesicular γ-adaptin-containing complex suggested that it has a subunit composition that is typical of that for a clathrin adaptor: in addition to the γ-adaptin subuni...
In the gastrointestinal (GI) epithelium, cellular differentiation occurs in five stages: stem cel... more In the gastrointestinal (GI) epithelium, cellular differentiation occurs in five stages: stem cells, precursor cells, transit cells, mature cells, and terminal cells. Stem cells are the least differentiated and have the greatest proliferation potential. In the stomach, they are located in the isthmus region of the pit-gland unit and give rise to four main cell lineages through precursor-amplifying cells: pre-pit cells give rise to mucous-secreting pit cells that migrate and reach the gastric luminal surface in 3 d; pre-neck cells differentiate into neck cells that migrate toward the bottom of the gland while changing their phenotype into the longest lived cells in the unit, zymogenic cells; pre-parietal cells complete their differentiation in the isthmus and then undergo bipolar migration to the pit and the base of the gland, where they have a life-span of about 2 mo. The precursors of enteroendocrine cells also originate in the isthmus and follow the bipolar mode of migration. In the small intestine, stem cells are located in the fourth cell layer from the crypt bottom and are derived from a single preceding cell (clonal). An adult mouse has about 1.1 million crypts and each crypt contains about 250 cells, of which about two-thirds go through the cell cycle every 12 h; each crypt produces about 13–16 new cells per hour! They give rise to four main cell lineages: absorptive, goblet, enteroendocrine, and Paneth. While members of the former three lineages differentiate while migrating upward along the crypt-villus axis, those of the latter complete their differentiation and remain at the crypt bottom. M-cell precursors are found in the intestinal crypts around lymphoid follicles and their mature forms migrate to cover the dome-shaped Peyer’s patches. In the colon, the lineages are columnar cells (80%), goblet cells (16%), deep crypt secretory cells (3%), and enteroendocrine cells (0.4%). Precursors of caveolated cells are also produced by stem cells throughout the GI tract.
Endoscopic biopsies of the upper gastrointestinal tract account for a significant amount of workl... more Endoscopic biopsies of the upper gastrointestinal tract account for a significant amount of workload for general and specialist histopathologists. The most common indications for gastric biopsy include diagnosis of various types of gastritis, peptic ulcer disease, confirmation of the presence of Helicobacter pylori, and neoplastic lesions. Histological recognition of subtle gastric mucosal infiltration by diffuse-type (signetring) adenocarcinoma is a well-recognized area of diagnostic difficulty. We present two examples of marked cytoplasmic vacuolation of parietal cells mimicking signet ring cell carcinoma.
Simple Summary The gastric epithelium comprises multiple cell types that undergo continuous renew... more Simple Summary The gastric epithelium comprises multiple cell types that undergo continuous renewal through controlled proliferation, differentiation and death. Several vitamins, such as vitamin D (VD), are known to contribute to tissue homeostasis and numerous studies have shown the importance of VD in different body organ systems. However, VD’s normal function in the stomach is understudied. To better understand the role of VD in the murine stomach, we initially confirmed the expression of VD receptors (VDR) in the stomach. Mice were fed a VD-deficient diet for 3 months. The results showed that the proton pump of acid-secreting parietal cells was downregulated in vitamin D-deficient mice and contributed to an abnormal gastric physiology. Moreover, this diet increased the gastrin hormone gene expression and increased gastric epithelial cell proliferation. These findings suggest essential biological roles for VDR and VD in gastric epithelial homeostasis. Future research will be requ...
Simple Summary The wall of the stomach is easily damaged by different factors leading to serious ... more Simple Summary The wall of the stomach is easily damaged by different factors leading to serious diseases such as ulcers and cancer. In this study, the effects of a mixture of different types of beneficial bacteria (De Simone Formulation) were investigated in a mouse model of stomach wall damages induced by single or multiple doses of acetylsalicylic acid. Control mice received water. The stomachs of all mice were processed for microscopic examination and labeling of dividing stem cells and stomach cell lineages secreting mucus, acid, pepsin, and hormones. The results reveal beneficial effects for the multiple bacterial strain of De Simone Formulation given before or after the induction of stomach erosions. The regeneration of the stomach wall was associated with an increase in stem cell proliferation and enhanced production of protective factors such as mucus, and restoration of the aggressive factors produced by acid and pepsin secreting cell lineages. Therefore, the protective an...
Biodegradable scaffolds are useful tools in the field of tissue engineering and regenerative medi... more Biodegradable scaffolds are useful tools in the field of tissue engineering and regenerative medicine. The aim of this study was to test the potential of the human stem cells of apical papilla (SCAP) to attach, proliferate and differentiate on a polycaprolactone (PCL)-based scaffolds. SCAP were extracted from the root apical papillae of freshly extracted immature premolar teeth by using enzymatic digestion. Porous PCL scaffolds were fabricated using particle leaching method and NaCl or mannitol as porogens. SCAP of passage 3 were seeded on non-porous and porous PCL scaffolds for up to 14 days. For control, cells were cultured on glass coverslips. Picogreen DNA quantification was used to assay for cell proliferation. Cell differentiation and development of calcification nodules were examined using scanning electron microscopy and alizarin red staining. SCAP showed a comparable attachment, growth and proliferation patterns on PCL scaffolds and coverslips. Cell proliferation was enhanced on mannitol scaffolds at all time points. Calcification nodules were detected in all PCL scaffolds while it was not present on glass coverslips. These nodules were detected on NaCl-scaffolds by day 7 and on mannitol and non-porous scaffolds by day 14. In conclusion, SCAP were able to attach, proliferate and differentiate on PCL scaffolds without using any inductive media, indicating their potential application for dental tissue regeneration.
Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry, and pharmacology, Jan 11, 2018
Breast cancer is the most common cancer in women worldwide, and within this cancer type, triple-n... more Breast cancer is the most common cancer in women worldwide, and within this cancer type, triple-negative breast cancers have the worst prognosis. The identification of new genes associated with triple-negative breast cancer progression is crucial for developing more specific anti-cancer targeted therapies, which could lead to a better management of these patients. In this context, we have recently demonstrated that SMARCAD1, a DEAD/H box-containing helicase, is involved in breast cancer cell migration, invasion, and metastasis. The aim of this study was to investigate the impact of the stable knockdown of SMARCAD1 on human breast cancer cell progression. Using two different designs of shRNA targeting SMARCAD1, we investigated the impact of the stable knockdown of SMARCAD1 on human breast cancer cell proliferation and colony growth in vitro and on tumour growth in chick embryo and nude mouse xenograft models in vivo using MDA-MB-231 (ER-/PR-/ HER2-) and T47D (ER+/PR+/-/HER2-) human b...
Breast cancer is the most common type of cancer and the leading cause of cancer-related deaths am... more Breast cancer is the most common type of cancer and the leading cause of cancer-related deaths among women in the United Arab Emirates and worldwide. Although many factors contribute to the high incidence of breast cancer, a considerable number of cases are related to environmental factors. In the present study, breast cancer was induced in female rats using a single dose, 80 mg/kg body wt, of the environmental carcinogen 7,12-dimethylbenz[a]anthracene (DMBA). The aim of the present study, was to characterize some of the molecular changes that occur during breast cancer development in the DMBA-treated rat model. Mammary gland tissues of control and DMBA-treated rats were processed for: i) immunohistochemical probing using anti-BRCA1 antibody to characterize and correlate the localization of this cell cycle protein during progression to cancer, ii) western blotting to analyze the alteration of p53 protein expression in preneoplastic and neoplastic lesions of the mammary glands, and i...
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Papers by Sherif M Karam