Neural tube defects

Neural tube defects (NTDs) are a group of malformations of the brain and spinal cord that originate at various times during gestation. The most common NTDs are anencephaly and meningomyelocele, which arise during the process of neurulation, a well-defined period between the 17th and 30th day after ovulation. These NTDs are clinically apparent by being open, ie, leaving nervous tissue exposed, in contrast to postneurulation NTDs that are skin covered. The incidence of NTDs is declining in several areas of the world, including the United States. While the reasons for this are unclear, there seems to be some effect from prenatal diagnosis, genetic counseling, and possibly nutritional supplementation.     

腹部外科常见感染性疾病的病原菌及药敏试验研究

为了了解本地区本医院腹部外科感染性疾病病原菌的构成比和药物敏感率的变化,指导临床用药,我们采用美国BD公司生产的6B和7D两种增菌瓶采集标本和培养细菌,并用该公司生产的生化板和药敏板,对1994～1996年269例常见的普外科感染性疾病患者的手术标本进行前瞻性的细菌培养和药敏试验研究.     

Retrospective analysis of fetal vertebral defects: Associated anomalies,etiologies, and outcome

Our objectives were to describe fetal cases of vertebral defects (VD), assess the diagnostic yield of fetal chromosomal analysis for VD and determine which investigations should be performed when evaluating fetal VD. We performed a retrospective chart review for fetuses with VD seen between 2006 and 2015. Cases were identified from CHU Sainte‐Justine's prenatal clinic visits, postmortem fetal skeletal surveys, and medical records. Cases with neural tube defects were excluded. Sixty‐six fetuses with VD were identified at a mean gestational age of 20 weeks. Forty‐seven (71.2%) had associated antenatal anomalies, most commonly genitourinary, skeletal/limb, and cardiac anomalies. Thirteen mothers (19.7%) had pregestational diabetes (95% CI [10.1%–29.3%]). Fifty‐three cases had chromosomal analysis. Three had abnormal results (5.6%): trisomy 13, trisomy 22, and 9q33.1q34.11 deletion. Thirty‐four (51.5%) pregnancies were terminated, one led to intrauterine fetal demise and 31 (46.9%) continued to term. Of 27 children who survived the neonatal period, 21 had congenital scoliosis and 3 had spondylocostal dysostosis. Seven had developmental delay. In conclusion, prenatal evaluation of fetuses with VD should include detailed morphological assessment (including fetal echocardiogram), maternal diabetes screening, and chromosomal microarray if non‐isolated. Our findings provide guidance about management and counseling after a diagnosis of fetal VD.     

Mutations in the structural gene for cytochrome c result in deficiency of both cytochromes aa 3 and c in Neurospora crassa

The cyt-12-12 mutant of Neurospora crassa is characterized by slow growth and a deficiency of spectrophotometrically-detectable cytochromes aa ₃ and c. Using a sib-selection procedure we have isolated the cyt-12 ⁺ allele from a cosmid library of N. crassa genomic DNA. Characterization of the cyt-12 ⁺ allele reveals that it encodes the structural gene for cytochrome c. DNA sequence analysis of the cyt-12-12 allele revealed a mutation in the cytochrome c coding sequence that results in replacement of a glycine residue, which is invariant in the cytochrome c of other species, with an aspartic acid. Genetic analysis confirms that cyt-12-12 is allelic with the previously-characterized cyc-1-1 mutant, which was also shown to affect the single locus encoding cytochrome c in N. crassa. We suggest that the amount of functional cytochrome c present in mitochondria influences the level of cytochrome aa ₃ .     

A locus for Bowen-Conradi syndrome maps to chromosome region 12p13.3

Bowen-Conradi syndrome (BCS) is a lethal autosomal recessive disorder with an estimated incidence of 1 in 355 live births in the Hutterite population. A few cases have been reported in other populations. Here, we report the results of a genome-wide scan and fine mapping of the BCS locus in Hutterite families. By linkage and haplotype analysis the BCS locus was mapped to a 3.5 cM segment (1.9 Mbp) in chromosome region 12p13.3 bounded by F8VWF and D12S397. When genealogical relationships among the families were taken into account in the linkage analysis, the evidence for linkage was stronger and the number of potentially linked regions was reduced to one. Under the assumption that all the Hutterite patients were identical by descent for a disease-causing mutation, haplotype analysis was used to infer likely historical recombinants and thereby narrow the candidate region to a chromosomal segment shared in common by all the affected children. This study also demonstrates that BCS and cerebro-oculo-facial-skeletal syndrome (COFS) are genetically distinct.