Gastroesophageal reflux in children with recurrent abdominal pain

In this study we investigated the presence of gastroesophageal reflux in children with recurrent abdominal pain and its possible relationship to food intolerance-associated duodenal inflammation. Twenty-four-hour intra-esophageal pH monitoring, an endoscopic duodenal biopsy and a small bowel 51Cr-EDTA permeability test were performed in 25 children with recurrent abdominal pain. In 14 cases (56%) the pH monitoring was abnormal, pointing to the presence of pathological gastroesophageal reflux. Treatment of gastroesophageal reflux in the latter patients resulted in resolution or improvement of abdominal pain in 10 cases (71%). Gastroesophageal reflux did not appear to be associated with either intestinal permeability to 51Cr-EDTA or duodenal biopsy findings. We conclude that pathological gastroesophageal reflex is a frequent finding in children with recurrent abdominal pain, that it is unrelated to duodenal inflammation and that there might be a causal relationship between pathological gastroesophageal reflux and recurrent abdominal pain in children.     

CD75s is a marker of murine CD8(+) suppressor T cells

We have previously described a monoclonal antibody, 984, which specifically recognizes murine CD8(+) suppressor T cells (Ts) but not CD8(+) cytolytic T lymphocytes (CTLs). Removal of 984(+) cells abrogates the suppressive effect of CD8(+) Ts generated either in vivo or in vitro while having no effect upon CTL. In this report, the molecules recognized by 984 are identified as 2-6 sialylated neolacto series gangliosides, which are members of the newly defined CD75s cluster. We proceed to demonstrate that like 984, a separate anti-CD75s antibody (CRIS-4), recognizes primary CD8(+) Ts cells. In addition, the 2,6 sialyltransferase responsible for the synthesis of the 984 epitope is identified, allowing the manipulation and study of the regulation of this epitope. This is the first report of CD75s on murine cells and the first report that delineates lymphocyte function based upon CD75s expression. In addition to contributing to the growing body of evidence that lineage dependent gangliosides are expressed by T lymphocytes, these findings suggest that CD8(+) CD75s(+) T lymphocytes represent a functionally distinct subset of CD8(+) T cells with negative regulatory function.     

Congenital gastrointestinal defects in Down syndrome: a report from the Atlanta and National Down Syndrome Projects

We report Down syndrome (DS)-associated congenital gastrointestinal (GI) defects identified during a 15 year, population-based study of the etiology and phenotypic consequences of trisomy 21. Between 1989 and 2004, six sites collected DNA, clinical and epidemiological information on live-born infants with standard trisomy 21 and their parents. We used chi-squared test and logistic regression to explore relationships between congenital GI defects and infant sex, race, maternal age, origin of the extra chromosome 21, and presence of a congenital heart defect. Congenital GI defects were present in 6.7% of 1892 eligible infants in this large, ethnically diverse, population-based study of DS. Defects included esophageal atresia/tracheoesophageal fistula (0.4%), pyloric stenosis (0.3%), duodenal stenosis/atresia (3.9%), Hirschsprung disease (0.8%), and anal stenosis/atresia (1.0%). We found no statistically significant associations between these defects and the factors examined. Although not significant, esophageal atresia was observed more often in infants of younger mothers and Hispanics, Hirschsprung disease was more frequent in males and in infants of younger mothers and blacks, and anal stenosis/atresia was found more often among females and Asians.     

Molecular analysis of VH and VL regions expressed in IgG-bearing chronic lymphocytic leukemia (CLL): further evidence that CLL is a heterogeneous group of tumors

We report the heavy (H) and light (L) chain variable (V) region sequences of cDNAs encoding the Ig receptor of two cases of CD5+ IgG- bearing CLL P87 and P103. In both CLL cases the H chain was encoded by members of the VH3 gene family. The L chain expressed by P87 belonged to the V lambda IV subgroup, whereas P103 used a member of the V kappa III subgroup. The VH3.P87 gene differed by only three nucleotides from 38P1, a VH3 gene previously cloned from a fetal liver cDNA library. Nucleotide sequence analysis demonstrated that the V kappa III.P103 gene differed by seven nucleotides from its most homologous germline counterpart, the Humkv325 gene, a highly conserved gene frequently expressed in IgM-bearing CLL. The nucleotide sequences of VH3.P103 and V lambda IV.P87 could not be reliably matched with reported germline V genes. The analysis of multiple independently obtained VH and VL cDNA clones from each tumor showed a lack of intraclonal diversification. The data show that V regions expressed in isotype-switched CD5+ CLL may be either in/near germline configuration or somatically mutated. Furthermore, these tumors, like their IgM-bearing counterparts, do not seem to undergo intraclonal diversification.     

Probing isoform-specific functions of polypeptide GalNAc-transferases using zinc finger nuclease glycoengineered SimpleCells

Our knowledge of the O-glycoproteome [N-acetylgalactosamine (GalNAc) type] is highly limited. The O-glycoproteome is differentially regulated in cells by dynamic expression of a subset of 20 polypeptide GalNAc-transferases (GalNAc-Ts), and methods to identify important functions of individual GalNAc-Ts are largely unavailable. We recently introduced SimpleCells, i.e., human cell lines made deficient in O-glycan extension by zinc finger nuclease targeting of a key gene in O-glycan elongation (Cosmc), which allows for proteome-wide discovery of O-glycoproteins. Here we have extended the SimpleCell concept to include proteome-wide discovery of unique functions of individual GalNAc-Ts. We used the GalNAc-T2 isoform implicated in dyslipidemia and the human HepG2 liver cell line to demonstrate unique functions of this isoform. We confirm that GalNAc-T2-directed site-specific O-glycosylation inhibits proprotein activation of the lipase inhibitor ANGPTL3 in HepG2 cells and further identify eight O-glycoproteins exclusively glycosylated by T2 of which one, ApoC-III, is implicated in dyslipidemia. Our study supports an essential role for GalNAc-T2 in lipid metabolism, provides serum biomarkers for GalNAc-T2 enzyme function, and validates the use of GALNT gene targeting with SimpleCells for broad discovery of disease-causing deficiencies in O-glycosylation. The presented glycoengineering strategy opens the way for proteome-wide discovery of functions of GalNAc-T isoforms and their role in congenital diseases and disorders.     

Mode of action of the IgG inhibitor of erythropoiesis in transient erythroblastopenia of children

Twelve cases of transient erythroblastopenia of childhood (TEC) have been studied to evaluate their marrow cell erythropoiesis in vitro and the effect on it of their serum or IgG. The number of colony-forming units-erythroid (CFU-E) and burst-forming units-erythroid (BFU-E) in the bone marrow of nine cases was extremely variable and did not allow any conclusion regarding the pathogenesis of this anemia. An IgG inhibitor of growth of erythroid colonies or bursts was detected in 8/12 cases. This IgG inhibitor had no effect on the growth of granulocyte-macrophage colonies. Further studies on its mode of action indicated that the IgG did not have antierythropoietin antibody properties and did not affect the mature erythroblasts, as shown by a lack of inhibition of their responses to erythropoietin and by the lack of a cytotoxic effect on 59Fe-labeled erythroblasts. In four cases, preincubation studies demonstrated a direct effect of the IgG on the CFU-E, which was complement-mediated in three cases and complement- independent in one case. In two other cases, the IgG suppressed the growth of normal BFU-E only without affecting the growth of CFU-E. The IgG inhibitor was no longer present after the erythroblastopenia had remitted. These studies demonstrate that in the majority of cases of TEC, an IgG suppressor of erythropoiesis in vitro is present. Its mode of action is heterogeneous regarding its requirement for complement. Its target cells are the earlier or later erythroid progenitors, BFU-E or CFU-E, but not the differentiated erythroblasts.     

A second exopolysaccharide of Rhizobium meliloti strain SU47 that can function in root nodule invasion.

Rhizobium meliloti strain SU47 produces the calcofluor-binding exopolysaccharide, succinoglycan, that is required for alfalfa root nodule invasion. Strains derived from R. meliloti SU47 secreted an acidic exopolysaccharide, EPSb, that replaced succinoglycan in nodule invasion. EPSb, which has not formerly been identified among the Rhizobiaceae, consisted of the repeating unit 4,6-O-(1-carboxyethylidene)-alpha-D-Galp1----3(X-O-Ac)-beta-D-G lcp1----3. EPSb synthesis occurred either in strains containing a mutation in a locus designated mucR or in strains with a recombinant cosmid pMuc. mucR mapped slightly counterclockwise from pyr49 on the chromosome, while pMuc contained genes mapping to the megaplasmid pRmeSU47b. In exoA, -F, and -H mutants, which are deficient in normal succinoglycan secretion and nodule invasion, a transposon Tn5 insertion in mucR or the presence of pMuc resulted in EPSb secretion and a restoration of nodule invasion on Medicago sativa and Melilotus alba. Mutants in exoB and exoC were incapable of succinoglycan and EPSb secretion as well as nodule invasion. A mutant that secreted succinoglycan but was incapable of EPSb secretion invaded nodules normally.