Alexandra W Einerhand - Academia.edu (original) (raw)
Papers by Alexandra W Einerhand
Rotavirus is the main cause of viral gastroenteritis in young children. Therefore, the developmen... more Rotavirus is the main cause of viral gastroenteritis in young children. Therefore, the development of inexpensive antiviral products for the prevention and/or treatment of rotavirus disease remains a priority. Previously we have shown that a recombinant monovalent antibody fragment (referred to as Anti-Rotavirus Proteins or ARP1) derived from a heavy chain antibody of a llama immunised with rotavirus was able to neutralise rotavirus infection in a mouse model system. In the present work we investigated the specificity and neutralising activity of two llama antibody fragments, ARP1 and ARP3, against 13 cell culture adapted rotavirus strains of diverse genotypes. In addition, immunocapture electron microscopy (IEM) was performed to determine binding of ARP1 to clinical isolates and cell culture adapted strains. ARP1 and ARP3 were able to neutralise a broad variety of rotavirus serotypes/genotypes in vitro, and in addition, IEM showed specific binding to a variety of cell adapted strains as well as strains from clinical specimens. These results indicated that these molecules could potentially be used as immunoprophylactic and/or immunotherapeutic products for the prevention and/or treatment of infection of a broad range of clinically relevant rotavirus strains.
To augment capacity-building for microbiome and probiotic research in Africa, a workshop was held... more To augment capacity-building for microbiome and probiotic research in Africa, a workshop was held in Nairobi, Kenya, at which researchers discussed human, animal, insect, and agricultural microbiome and probiotics/prebiotics topics. Five recommendations were made to promote future basic and translational research that benefits Africans.
Human Pathology, 2003
The origin of gastric metaplasia of the duodenum (GMD) remains enigmatic. We studied expression o... more The origin of gastric metaplasia of the duodenum (GMD) remains enigmatic. We studied expression of mucins and trefoil peptides in GMD to gain insight into its phenotype and origin. We examined duodenal tissue of 95 patients (0 to 83 years old, 26 with gastric H. pylori-infection) for presence of GMD. Expression was examined immunohistochemically of secretory mucins (MUC2, MUC5AC, MUC5B, and MUC6), trefoil peptides (TFF1, TFF2, and TFF3), and sucrase-isomaltase (SI). GMD, found in 37 patients, correlated positively to gastric H. pylori-infection, age, and villus atrophy. MUC2 and TFF3, expressed in normal goblet cells, were absent from 100% and 87% of GMD, respectively. GMD ubiquitously expressed MUC5AC, whereas MUC5AC expression in adjacent goblet cells was closely correlated with the extent of GMD. TFF1, TFF2, and MUC6 were found in 84%, 92%, and 65% of GMD, respectively. MUC5B was absent from epithelium and GMD. SI, expressed by villus enterocytes, was absent from GMD. Brunner's glands ubiquitously expressed MUC5B, MUC6, and TFF2. GMD was characterized by expression of gastric-type proteins MUC5AC, MUC6, TFF1, and TFF2 and absence of intestinal markers MUC2, TFF3, and SI. In terms of the location of metaplastic cells, our results suggest that epithelial cells migrating towards villus tips switch to gastric-type secretory cells. Positive correlation with infection suggests an inductive role of H. pylori in development of GMD.
Journal of Pediatric Gastroenterology and Nutrition
Helicobacter, 2003
h a a p p t t e e r r M MU UC C5 5A AC C g gl ly yc co op pr ro ot te ei in n i is s t th he e p ... more h a a p p t t e e r r M MU UC C5 5A AC C g gl ly yc co op pr ro ot te ei in n i is s t th he e p pr ri im ma ar ry y r re ec ce ep pt to or r f fo or r H He el li ic co ob ba ac ct te er r p py yl lo or ri i i in n h hu um ma an n s st to om ma ac ch h Abstract Background and Objectives: Helicobacter pylori shows a characteristic tropism for the mucusproducing gastric epithelium. In infected patients, H. pylori co-localizes in situ with the gastric secretory mucin MUC5AC. The carbohydrate blood-group antigen Lewis B (LeB) was deemed responsible for the adherence of H. pylori to the gastric surface epithelium. We sought to determine if MUC5AC is the carrier of LeB, and thus if MUC5AC is the underlying gene product, functioning as main receptor for H. pylori in stomach. Methods: We studied three types of human tissue producing MUC5AC: Barrett's esophagus (BE), normal gastric tissue, and gastric metaplasia of the duodenum (GMD). Tissue sections were immuno-fluorescently stained for MUC5AC or LeB, and subsequently incubated with one of three strains of Texas red-labeled H. pylori, one of which was unable to bind to LeB. We determined the colocalization of MUC5AC or LeB with adherent H. pylori. Results: The binding patterns for the two LeB-binding strains to all tissues were similar, whereas the strain unable to bind to LeB did not bind to any of the tissues. In normal gastric tissue, the LeB-binding strains always bound to MUC5AC-and LeB-positive epithelial cells. In four non-secretor patients colocalization of the LeB-binding strains was found to MUC5AC-positive gastric epithelial cells.
Digestive Diseases and Sciences, 2005
We have investigated how gastric H. pylori infection affects antrum secretory cell types by study... more We have investigated how gastric H. pylori infection affects antrum secretory cell types by studying the expression of secretory proteins in antrum epithelium. Antrum biopsy specimens were prospectively collected from 102 individuals (49 H. pylori-infected). Immunohistochemistry was performed for secretory mucins (MUC5AC, MUC5B, MUC6), Trefoil factor family (TFF)-peptides (TFF1, TFF2), endocrine peptides (gastrin, chromogranin A), and proliferating cells (Ki-67). Protein expression was quantified morphometrically. H. pylori infection was significantly correlated to mucosal inflammation and to epithelial atrophy and proliferation. In H. pylori-infected patients the number of proliferating cells increased significantly, and the zone of proliferating cells shifted toward the surface epithelium of the antral glands. Infection was correlated with decreased MUC5AC, TFF1, and TFF2 expression and increased MUC6 and MUC5B expression. Endocrine cells expressing chromagranin A and gastrin shifted toward the surface epithelium of the antral glands in H. pylori-infected patients. H. pylori infection and concomitant inflammation induced increased epithelial proliferation and triggered coordinate deregulation of secretory cell populations in the antrum. In particular, infection led to a coordinated increase in cells expressing MUC6 and MUC5B at the expense of MUC5AC-producing cells.
Biochemical and Biophysical Research Communications, Apr 28, 1998
of a family of at least nine genes designated MUC1-8 To further clone the human gastric mucin MUC... more of a family of at least nine genes designated MUC1-8 To further clone the human gastric mucin MUC5AC including MUC5B and MUC5AC (3). The MUC5 subdi-cDNA, we screened a human gastric cDNA library with vision into MUC5AC and MUC5B is due to the fact that previously identified MUC5AC sequences. We obtained Nguyen and co-workers initially cloned partial MUC5 32 independent clones encoding newly identified se-cDNAs from tracheo-bronchial tissue, and designated quences comprising the entire N-terminal sequence of these MUC5A, MUC5B and MUC5C (4). Although all MUC5AC, up to 3024 bp upstream of the previously were assigned to chromosome 11p15, it was subseidentified MUC5AC sequences. The N-terminus of quently shown by physical mapping that the partial MUC5AC shows high homology (43% identity) with MUC5A and MUC5C cDNAs were derived from the the N-terminus of MUC2 and contains three domains same gene, whereas MUC5B was not. Therefore, the homologous to the D-domains found in the pro-von genes are now defined as MUC5AC and MUC5B, re-Willebrand factor. Furthermore, the N-terminus of spectively (5, 6).
Human pathology, 2002
Barrett's esophagus (BE) consists of metaplastic epithelium of the esophagus, generally diagn... more Barrett's esophagus (BE) consists of metaplastic epithelium of the esophagus, generally diagnosed by mucin histochemistry. We aimed to determine which mucins were expressed in BE, and to relate their expression to BE pathology. Archival biopsies of 4 patient groups were selected, based on standard histochemistry: BE without inflammation, BE with inflammation, ulcerating BE, and BE with dysplasia. Sections were stained by immunohistochemistry for secretory mucins (MUC2, MUC5AC, MUC5B, and MUC6), the proliferation marker Ki-67, and mucin-associated trefoil factor family (TFF) peptides (TFF1, TFF2, and TFF3). MUC5AC and TFF2 were expressed at similar high levels in each clinical group. Intestinal metaplasia (IM), detected both histochemically and by the intestinal mucin MUC2, was lowest in inflamed BE. The expression of the intestinal-type TFF3 did not differ among the groups. Ulcerating BE was distinguished by very low expression of MUC6 and MUC5B, but very high expression of TFF1...
Biochemical and Biophysical Research Communications, 1998
of a family of at least nine genes designated MUC1-8 To further clone the human gastric mucin MUC... more of a family of at least nine genes designated MUC1-8 To further clone the human gastric mucin MUC5AC including MUC5B and MUC5AC (3). The MUC5 subdi-cDNA, we screened a human gastric cDNA library with vision into MUC5AC and MUC5B is due to the fact that previously identified MUC5AC sequences. We obtained Nguyen and co-workers initially cloned partial MUC5 32 independent clones encoding newly identified se-cDNAs from tracheo-bronchial tissue, and designated quences comprising the entire N-terminal sequence of these MUC5A, MUC5B and MUC5C (4). Although all MUC5AC, up to 3024 bp upstream of the previously were assigned to chromosome 11p15, it was subseidentified MUC5AC sequences. The N-terminus of quently shown by physical mapping that the partial MUC5AC shows high homology (43% identity) with MUC5A and MUC5C cDNAs were derived from the the N-terminus of MUC2 and contains three domains same gene, whereas MUC5B was not. Therefore, the homologous to the D-domains found in the pro-von genes are now defined as MUC5AC and MUC5B, re-Willebrand factor. Furthermore, the N-terminus of spectively (5, 6).
Rotavirus is the most important cause of infantile gastroenteritis. Since in vivo mucosal respons... more Rotavirus is the most important cause of infantile gastroenteritis. Since in vivo mucosal responses to a rotavirus infection thus far have not been extensively studied, we related viral replication in the murine small intestine to alterations in mucosal structure, epithelial cell homeostasis, cellular kinetics, and differentiation. Seven-day-old suckling BALB/c mice were inoculated with 2 10 4 focus-forming units of murine rotavirus and were compared to mock-infected controls. Diarrheal illness and viral shedding were recorded, and small intestinal tissue was evaluated for rotavirus (NSP4 and structural proteins)-and enterocyte-specific (lactase, SGLT1, and L-FABP) mRNA and protein expression. Morphology, apoptosis, proliferation, and migration were evaluated (immuno)histochemically. Diarrhea was observed from days 1 to 5 postinfection, and viral shedding was observed from days 1 to 10. Two peaks of rotavirus replication were observed at 1 and 4 days postinfection. Histological changes were characterized by the accumulation of vacuolated enterocytes. Strikingly , the number of vacuolated cells exceeded the number of cells in which viral replication was detectable. Apoptosis and proliferation were increased from days 1 to 7, resulting in villous atrophy. Epithelial cell turnover was significantly higher (<4 days) than that observed in controls (7 days). Since epithelial renewal occurred within 4 days, the second peak of viral replication was most likely caused by infection of newly synthesized cells. Expression of enterocyte-specific genes was downregulated in infected cells at mRNA and protein levels starting as early as 6 h after infection. In conclusion, we show for the first time that rotavirus infection induces apoptosis in vivo, an increase in epithelial cell turnover, and a shutoff of gene expression in enterocytes showing viral replication. The shutoff of enterocyte-specific gene expression, together with the loss of mature enterocytes through apoptosis and the replacement of these cells by less differentiated dividing cells, likely leads to a defective absorptive function of the intestinal epithelium, which contributes to rotavirus pathogenesis.
Journal of Histochemistry & Cytochemistry, 1998
The clinical importance of carbamoyl phosphate synthase I (CPSI) relates to its capacity to metab... more The clinical importance of carbamoyl phosphate synthase I (CPSI) relates to its capacity to metabolize ammonia, because CPSI deficiencies cause lethal serum ammonia levels. Although some metabolic parameters concerning liver and intestinal CPSI have been reported, the extent to which enterocytes contribute to ammonia conversion remains unclear without a detailed description of its developmental and spatial expression patterns. Therefore, we determined the patterns of enterocytic CPSI mRNA and protein expression in human and rat intestine during embryonic and postnatal development, using in situ hybridization and immunohistochemistry. CPSI protein appeared during human embryogenesis in liver at 31-35 e.d. (embryonic days) before intestine (59 e.d.), whereas in rat CPSI detection in intestine (at 16 e.d.) preceded liver (20 e.d.). During all stages of development there was a good correlation between the expression of CPSI protein and mRNA in the intestinal epithelium. Strikingly, duodenal enterocytes in both species exhibited mosaic CPSI protein expression despite uniform CPSI mRNA expression in the epithelium and the presence of functional mitochondria in all epithelial cells. Unlike rat, CPSI in human embryos was expressed in liver before intestine. Although CPSI was primarily regulated at the transcriptional level, CPSI protein appeared mosaic in the duodenum of both species, possibly due to post-transcriptional regulation.
Journal of Pediatric Gastroenterology & Nutrition, 1998
Background: Duodenal mucosal biopsies are routinely taken for diagnosis in children with complain... more Background: Duodenal mucosal biopsies are routinely taken for diagnosis in children with complaints of the upper gastrointestinal tract. Surprisingly, little is known about the usefulness of proximal duodenal versus distal duodenal biopsies for routine diagnostic purposes. This study evaluated the comparability of proximal and distal duodenal biopsies with respect to mucosal morphology as well as glycohydrolase expression as an indicator of intestinal epithelial function.
Nederlands tijdschrift voor geneeskunde, Jan 26, 1994
Gut, 1996
Background-It has been shown that MUC2 is the prominent mucin synthesised in healthy colon. Aim-T... more Background-It has been shown that MUC2 is the prominent mucin synthesised in healthy colon. Aim-To identify the predominant mucins in ulcerative colitis (UC) and to study their biosynthesis. Methods and Results-Mucin was purified from UC resection specimens. This mucin on sodium dodecylsulphate polyacrylamide gel electrophoresis (SDS-PAGE) presented as one, high molecular weight, periodic acid/Schiff's reagent (PAS) stainable band. Amino acid composition showed a close resemblance to that of MUC2. Immunoprecipitation with a specific anti-MUC2 antiserum confirmed that this mucin was MUC2. In addition, on the mRNA level MUC2 was also the most prominent mucin expressed in UC. Polyclonal antiserum was elicited, mainly recognising mucin peptide epitopes of UC and normal colonic mucin.
European Journal of Gastroenterology & Hepatology, 1998
Biochemical Society transactions, 1995
Rotavirus is the main cause of viral gastroenteritis in young children. Therefore, the developmen... more Rotavirus is the main cause of viral gastroenteritis in young children. Therefore, the development of inexpensive antiviral products for the prevention and/or treatment of rotavirus disease remains a priority. Previously we have shown that a recombinant monovalent antibody fragment (referred to as Anti-Rotavirus Proteins or ARP1) derived from a heavy chain antibody of a llama immunised with rotavirus was able to neutralise rotavirus infection in a mouse model system. In the present work we investigated the specificity and neutralising activity of two llama antibody fragments, ARP1 and ARP3, against 13 cell culture adapted rotavirus strains of diverse genotypes. In addition, immunocapture electron microscopy (IEM) was performed to determine binding of ARP1 to clinical isolates and cell culture adapted strains. ARP1 and ARP3 were able to neutralise a broad variety of rotavirus serotypes/genotypes in vitro, and in addition, IEM showed specific binding to a variety of cell adapted strains as well as strains from clinical specimens. These results indicated that these molecules could potentially be used as immunoprophylactic and/or immunotherapeutic products for the prevention and/or treatment of infection of a broad range of clinically relevant rotavirus strains.
To augment capacity-building for microbiome and probiotic research in Africa, a workshop was held... more To augment capacity-building for microbiome and probiotic research in Africa, a workshop was held in Nairobi, Kenya, at which researchers discussed human, animal, insect, and agricultural microbiome and probiotics/prebiotics topics. Five recommendations were made to promote future basic and translational research that benefits Africans.
Human Pathology, 2003
The origin of gastric metaplasia of the duodenum (GMD) remains enigmatic. We studied expression o... more The origin of gastric metaplasia of the duodenum (GMD) remains enigmatic. We studied expression of mucins and trefoil peptides in GMD to gain insight into its phenotype and origin. We examined duodenal tissue of 95 patients (0 to 83 years old, 26 with gastric H. pylori-infection) for presence of GMD. Expression was examined immunohistochemically of secretory mucins (MUC2, MUC5AC, MUC5B, and MUC6), trefoil peptides (TFF1, TFF2, and TFF3), and sucrase-isomaltase (SI). GMD, found in 37 patients, correlated positively to gastric H. pylori-infection, age, and villus atrophy. MUC2 and TFF3, expressed in normal goblet cells, were absent from 100% and 87% of GMD, respectively. GMD ubiquitously expressed MUC5AC, whereas MUC5AC expression in adjacent goblet cells was closely correlated with the extent of GMD. TFF1, TFF2, and MUC6 were found in 84%, 92%, and 65% of GMD, respectively. MUC5B was absent from epithelium and GMD. SI, expressed by villus enterocytes, was absent from GMD. Brunner's glands ubiquitously expressed MUC5B, MUC6, and TFF2. GMD was characterized by expression of gastric-type proteins MUC5AC, MUC6, TFF1, and TFF2 and absence of intestinal markers MUC2, TFF3, and SI. In terms of the location of metaplastic cells, our results suggest that epithelial cells migrating towards villus tips switch to gastric-type secretory cells. Positive correlation with infection suggests an inductive role of H. pylori in development of GMD.
Journal of Pediatric Gastroenterology and Nutrition
Helicobacter, 2003
h a a p p t t e e r r M MU UC C5 5A AC C g gl ly yc co op pr ro ot te ei in n i is s t th he e p ... more h a a p p t t e e r r M MU UC C5 5A AC C g gl ly yc co op pr ro ot te ei in n i is s t th he e p pr ri im ma ar ry y r re ec ce ep pt to or r f fo or r H He el li ic co ob ba ac ct te er r p py yl lo or ri i i in n h hu um ma an n s st to om ma ac ch h Abstract Background and Objectives: Helicobacter pylori shows a characteristic tropism for the mucusproducing gastric epithelium. In infected patients, H. pylori co-localizes in situ with the gastric secretory mucin MUC5AC. The carbohydrate blood-group antigen Lewis B (LeB) was deemed responsible for the adherence of H. pylori to the gastric surface epithelium. We sought to determine if MUC5AC is the carrier of LeB, and thus if MUC5AC is the underlying gene product, functioning as main receptor for H. pylori in stomach. Methods: We studied three types of human tissue producing MUC5AC: Barrett's esophagus (BE), normal gastric tissue, and gastric metaplasia of the duodenum (GMD). Tissue sections were immuno-fluorescently stained for MUC5AC or LeB, and subsequently incubated with one of three strains of Texas red-labeled H. pylori, one of which was unable to bind to LeB. We determined the colocalization of MUC5AC or LeB with adherent H. pylori. Results: The binding patterns for the two LeB-binding strains to all tissues were similar, whereas the strain unable to bind to LeB did not bind to any of the tissues. In normal gastric tissue, the LeB-binding strains always bound to MUC5AC-and LeB-positive epithelial cells. In four non-secretor patients colocalization of the LeB-binding strains was found to MUC5AC-positive gastric epithelial cells.
Digestive Diseases and Sciences, 2005
We have investigated how gastric H. pylori infection affects antrum secretory cell types by study... more We have investigated how gastric H. pylori infection affects antrum secretory cell types by studying the expression of secretory proteins in antrum epithelium. Antrum biopsy specimens were prospectively collected from 102 individuals (49 H. pylori-infected). Immunohistochemistry was performed for secretory mucins (MUC5AC, MUC5B, MUC6), Trefoil factor family (TFF)-peptides (TFF1, TFF2), endocrine peptides (gastrin, chromogranin A), and proliferating cells (Ki-67). Protein expression was quantified morphometrically. H. pylori infection was significantly correlated to mucosal inflammation and to epithelial atrophy and proliferation. In H. pylori-infected patients the number of proliferating cells increased significantly, and the zone of proliferating cells shifted toward the surface epithelium of the antral glands. Infection was correlated with decreased MUC5AC, TFF1, and TFF2 expression and increased MUC6 and MUC5B expression. Endocrine cells expressing chromagranin A and gastrin shifted toward the surface epithelium of the antral glands in H. pylori-infected patients. H. pylori infection and concomitant inflammation induced increased epithelial proliferation and triggered coordinate deregulation of secretory cell populations in the antrum. In particular, infection led to a coordinated increase in cells expressing MUC6 and MUC5B at the expense of MUC5AC-producing cells.
Biochemical and Biophysical Research Communications, Apr 28, 1998
of a family of at least nine genes designated MUC1-8 To further clone the human gastric mucin MUC... more of a family of at least nine genes designated MUC1-8 To further clone the human gastric mucin MUC5AC including MUC5B and MUC5AC (3). The MUC5 subdi-cDNA, we screened a human gastric cDNA library with vision into MUC5AC and MUC5B is due to the fact that previously identified MUC5AC sequences. We obtained Nguyen and co-workers initially cloned partial MUC5 32 independent clones encoding newly identified se-cDNAs from tracheo-bronchial tissue, and designated quences comprising the entire N-terminal sequence of these MUC5A, MUC5B and MUC5C (4). Although all MUC5AC, up to 3024 bp upstream of the previously were assigned to chromosome 11p15, it was subseidentified MUC5AC sequences. The N-terminus of quently shown by physical mapping that the partial MUC5AC shows high homology (43% identity) with MUC5A and MUC5C cDNAs were derived from the the N-terminus of MUC2 and contains three domains same gene, whereas MUC5B was not. Therefore, the homologous to the D-domains found in the pro-von genes are now defined as MUC5AC and MUC5B, re-Willebrand factor. Furthermore, the N-terminus of spectively (5, 6).
Human pathology, 2002
Barrett's esophagus (BE) consists of metaplastic epithelium of the esophagus, generally diagn... more Barrett's esophagus (BE) consists of metaplastic epithelium of the esophagus, generally diagnosed by mucin histochemistry. We aimed to determine which mucins were expressed in BE, and to relate their expression to BE pathology. Archival biopsies of 4 patient groups were selected, based on standard histochemistry: BE without inflammation, BE with inflammation, ulcerating BE, and BE with dysplasia. Sections were stained by immunohistochemistry for secretory mucins (MUC2, MUC5AC, MUC5B, and MUC6), the proliferation marker Ki-67, and mucin-associated trefoil factor family (TFF) peptides (TFF1, TFF2, and TFF3). MUC5AC and TFF2 were expressed at similar high levels in each clinical group. Intestinal metaplasia (IM), detected both histochemically and by the intestinal mucin MUC2, was lowest in inflamed BE. The expression of the intestinal-type TFF3 did not differ among the groups. Ulcerating BE was distinguished by very low expression of MUC6 and MUC5B, but very high expression of TFF1...
Biochemical and Biophysical Research Communications, 1998
of a family of at least nine genes designated MUC1-8 To further clone the human gastric mucin MUC... more of a family of at least nine genes designated MUC1-8 To further clone the human gastric mucin MUC5AC including MUC5B and MUC5AC (3). The MUC5 subdi-cDNA, we screened a human gastric cDNA library with vision into MUC5AC and MUC5B is due to the fact that previously identified MUC5AC sequences. We obtained Nguyen and co-workers initially cloned partial MUC5 32 independent clones encoding newly identified se-cDNAs from tracheo-bronchial tissue, and designated quences comprising the entire N-terminal sequence of these MUC5A, MUC5B and MUC5C (4). Although all MUC5AC, up to 3024 bp upstream of the previously were assigned to chromosome 11p15, it was subseidentified MUC5AC sequences. The N-terminus of quently shown by physical mapping that the partial MUC5AC shows high homology (43% identity) with MUC5A and MUC5C cDNAs were derived from the the N-terminus of MUC2 and contains three domains same gene, whereas MUC5B was not. Therefore, the homologous to the D-domains found in the pro-von genes are now defined as MUC5AC and MUC5B, re-Willebrand factor. Furthermore, the N-terminus of spectively (5, 6).
Rotavirus is the most important cause of infantile gastroenteritis. Since in vivo mucosal respons... more Rotavirus is the most important cause of infantile gastroenteritis. Since in vivo mucosal responses to a rotavirus infection thus far have not been extensively studied, we related viral replication in the murine small intestine to alterations in mucosal structure, epithelial cell homeostasis, cellular kinetics, and differentiation. Seven-day-old suckling BALB/c mice were inoculated with 2 10 4 focus-forming units of murine rotavirus and were compared to mock-infected controls. Diarrheal illness and viral shedding were recorded, and small intestinal tissue was evaluated for rotavirus (NSP4 and structural proteins)-and enterocyte-specific (lactase, SGLT1, and L-FABP) mRNA and protein expression. Morphology, apoptosis, proliferation, and migration were evaluated (immuno)histochemically. Diarrhea was observed from days 1 to 5 postinfection, and viral shedding was observed from days 1 to 10. Two peaks of rotavirus replication were observed at 1 and 4 days postinfection. Histological changes were characterized by the accumulation of vacuolated enterocytes. Strikingly , the number of vacuolated cells exceeded the number of cells in which viral replication was detectable. Apoptosis and proliferation were increased from days 1 to 7, resulting in villous atrophy. Epithelial cell turnover was significantly higher (<4 days) than that observed in controls (7 days). Since epithelial renewal occurred within 4 days, the second peak of viral replication was most likely caused by infection of newly synthesized cells. Expression of enterocyte-specific genes was downregulated in infected cells at mRNA and protein levels starting as early as 6 h after infection. In conclusion, we show for the first time that rotavirus infection induces apoptosis in vivo, an increase in epithelial cell turnover, and a shutoff of gene expression in enterocytes showing viral replication. The shutoff of enterocyte-specific gene expression, together with the loss of mature enterocytes through apoptosis and the replacement of these cells by less differentiated dividing cells, likely leads to a defective absorptive function of the intestinal epithelium, which contributes to rotavirus pathogenesis.
Journal of Histochemistry & Cytochemistry, 1998
The clinical importance of carbamoyl phosphate synthase I (CPSI) relates to its capacity to metab... more The clinical importance of carbamoyl phosphate synthase I (CPSI) relates to its capacity to metabolize ammonia, because CPSI deficiencies cause lethal serum ammonia levels. Although some metabolic parameters concerning liver and intestinal CPSI have been reported, the extent to which enterocytes contribute to ammonia conversion remains unclear without a detailed description of its developmental and spatial expression patterns. Therefore, we determined the patterns of enterocytic CPSI mRNA and protein expression in human and rat intestine during embryonic and postnatal development, using in situ hybridization and immunohistochemistry. CPSI protein appeared during human embryogenesis in liver at 31-35 e.d. (embryonic days) before intestine (59 e.d.), whereas in rat CPSI detection in intestine (at 16 e.d.) preceded liver (20 e.d.). During all stages of development there was a good correlation between the expression of CPSI protein and mRNA in the intestinal epithelium. Strikingly, duodenal enterocytes in both species exhibited mosaic CPSI protein expression despite uniform CPSI mRNA expression in the epithelium and the presence of functional mitochondria in all epithelial cells. Unlike rat, CPSI in human embryos was expressed in liver before intestine. Although CPSI was primarily regulated at the transcriptional level, CPSI protein appeared mosaic in the duodenum of both species, possibly due to post-transcriptional regulation.
Journal of Pediatric Gastroenterology & Nutrition, 1998
Background: Duodenal mucosal biopsies are routinely taken for diagnosis in children with complain... more Background: Duodenal mucosal biopsies are routinely taken for diagnosis in children with complaints of the upper gastrointestinal tract. Surprisingly, little is known about the usefulness of proximal duodenal versus distal duodenal biopsies for routine diagnostic purposes. This study evaluated the comparability of proximal and distal duodenal biopsies with respect to mucosal morphology as well as glycohydrolase expression as an indicator of intestinal epithelial function.
Nederlands tijdschrift voor geneeskunde, Jan 26, 1994
Gut, 1996
Background-It has been shown that MUC2 is the prominent mucin synthesised in healthy colon. Aim-T... more Background-It has been shown that MUC2 is the prominent mucin synthesised in healthy colon. Aim-To identify the predominant mucins in ulcerative colitis (UC) and to study their biosynthesis. Methods and Results-Mucin was purified from UC resection specimens. This mucin on sodium dodecylsulphate polyacrylamide gel electrophoresis (SDS-PAGE) presented as one, high molecular weight, periodic acid/Schiff's reagent (PAS) stainable band. Amino acid composition showed a close resemblance to that of MUC2. Immunoprecipitation with a specific anti-MUC2 antiserum confirmed that this mucin was MUC2. In addition, on the mRNA level MUC2 was also the most prominent mucin expressed in UC. Polyclonal antiserum was elicited, mainly recognising mucin peptide epitopes of UC and normal colonic mucin.
European Journal of Gastroenterology & Hepatology, 1998
Biochemical Society transactions, 1995