IGF-1和FGF-2对神经母细胞瘤细胞分化及SOCS表达的影响

目的 研究胰岛素样生长因子-1（IGF-1）与碱性成纤维细胞生长因子（FGF-2）对神经细胞增殖与分化的共同作用，并探讨SOCS基因表达与二者作用的关系。方法 选用人类神经母细胞瘤SK-N-MC细胞系作为神经细胞的体外模型，分别用IGF-1，FGF-2及联合应用IGF-1和FGF-2处理细胞，于处理后24、48和72h分别观察细胞数量、形态学变化；收获培养48h的细胞，提取总RNA，用RT-PCR法检测SOCS1、2、3 mRNA的表达。结果 处理后24h各组细胞数量及形态无明显变化；处理后48、72h IGF-1组细胞数量较对照组增多，形态上无明显变化，SOCS2 mRNA表达显著下调；FGF-2组细胞数量减少，形态呈明显分化，SOCS2 mRNA表达高于对照组：而IGF-1和FGF-2联合组细胞数量、形态及SOCS2 mRNA表达变化与FGF-2组相似，但程度上更加显著。结论 FGF-2可以削减IGF-1所诱导的人类神经母细胞瘤细胞的增殖作用，而SOCS2 mRNA表达上调可能为其作用机制之一。     

Familial hypomagnesemia maps to chromosome 9q, not to the X chromosome: genetic linkage mapping and analysis of a balanced translocation breakpoint

Familial hypomagnesemia with secondary hypocalcemia (HSH) (MIM 307600) was studied in three inbred Bedouin kindreds from Israel. The three kindreds, one extended and two nuclear families, contained 13 affected individuals, 11 males and two females. Assuming that the individuals affected with hypomagnesemia shared a chromosomal region inherited from a common ancestor, we used a DNA pooling strategy in a genome-wide search for loci which show homozygosity for shared alleles in affected individuals. DNA samples from affected individuals within a single kindred were pooled and used as the template for PCR amplification of short tandem repeat polymorphic markers (STRPs). Pooled DNA from unaffected siblings and parents were used as controls. A shift towards homozygosity was observed in the affected DNA pool compared with the control pools with D9S301 (GATA7D12). Genotyping of individual DNA samples with D9S301 and several flanking markers confirmed linkage to chromosome 9 with maximum LOD scores of 3.4 (theta = 0.05), 3.7 (theta = 0) and 2.3 (theta = 0) for the three families. We have identified a 14 cM interval on chromosome 9 (9q12-9q22.2), flanked by proximal marker D9S1874 and distal marker D9S1807, within which all affected individuals from the three kindreds are homozygous for a shared haplotype. The disease segregates with a common affected haplotype in the three families, suggesting that hypomagnesemia is caused by a common ancestral mutation in these families. Although HSH has been previously reported to be X linked, these linkage data demonstrate that the disorder is an autosomal recessive disease in these kindreds. Mapping of a chromosomal breakpoint in a somatic cell line established from a patient with HSH and a balanced X;9 translocation placed the chromosomal breakpoint in a 500 kb region flanked by D9S1844 and D9S273. Identification of the gene responsible for hypomagnesemia will provide insight into the regulation of this essential cation.      

DNA-based diagnostic tests for Salmonella species targeting agfA, the structural gene for thin, aggregative fimbriae.

Salmonella enteritidis 27655-3b and a few diarrheagenic Escherichia coli strains produce morphologically and antigenically related, thin, aggregative fimbriae, collectively named GVVPQ fimbriae (S. K. Collinson, L. Emödy, T. J. Trust, and W. W. Kay, J. Bacteriol. 174:4490-4495, 1992). To determine whether GVVPQ fimbriae are common to Salmonella spp. and other enteropathogenic members of the family Enterobacteriaceae, 113 isolates were phenotypically screened for Congo red binding and aggregative colony morphology. Presumptive positive and representative negative strains were examined by Western blotting (immunoblotting) by using antiserum to SEF 17, the native GVVPQ fimbria of S. enteritidis. Only four S. enteritidis strains and six E. coli isolates possessed substantial amounts of GVVPQ fimbriae after 24 h of incubation on T medium. Following 5 days of incubation, 56 of 93 Salmonella isolates (60%) and 1 of 7 additional E. coli clinical isolates possessed detectable levels of GVVPQ fimbriae. Since variable expression of GVVPQ fimbriae was observed among Salmonella isolates and some E. coli strains produced scant amounts, as revealed by immunoelectron microscopy, the ability to produce these fimbriae was evaluated by genotypic screening. The structural gene for the SEF 17 fimbrin, agfA, was amplified by the polymerase chain reaction, cloned, and sequenced to provide a characterized DNA probe. An agfA DNA fragment hybridized strongly to 603 of 604 (99.8%) Salmonella isolates but very weakly to 31 of 266 other members of the family Enterobacteriaceae including 26 of 137 E. coli strains, 3 of 14 Citrobacter spp., and single isolates of Shigella sonnei and Enterobacter cloacae. The agfA DNA probe proved to be a valuable diagnostic tool for Salmonella isolates arrayed on hydrophobic grid membrane filters. Unique agfA sequences were targeted in the development of a polymerase chain reaction assay specific for Salmonella spp.     

Cell surface expression of c-kit receptors by childhood acute myeloid leukemia blasts is not of prognostic value: a report from the Childrens Cancer Group

The prognostic significance of c-kit receptor expression on leukemic blast cells was determined in 122 children with acute myeloid leukemia (AML) entered onto Childrens Cancer Group protocol 213. Clinical and laboratory characteristics as well as outcome were analyzed according to the percentage of blast cells expressing c-kit receptors and the relative number of c-kit receptors per cell as determined by indirect immunofluorescence. c-kit receptor expression was strongly associated with the expression of the CD34 antigen. However, contrary to findings in adult patients with AML, c-kit receptor expression by childhood AML blast cells was not predictive of a poor response to therapy.     

Ileal meconium plugs

Eleven cases of neonatal intestinal obstruction associated with a white ileal meconium plug are described; 6 of these presented with complications--such as, giant meconium pseudocyst, perforation, volvulus, or atresia. Most of these complications are presumed to have arisen during the intrauterine period. Only one patient could be relieved of the ileal meconium plug by enemas. The condition of ileal meconium plug is not as benign as a meconium plug in the rectum or distal colon. A plea is made to restrict the name meconium plug syndrome to cases in which the meconium plug is white and chalky and the consequent intestinal obstruction can be relieved by enemas, without evidence of intestinal dysfunction in later life.