👤 Weilin Lu

With the strategy of homologue molecular cloning using the sequence of the maleless gene (mle) of Drosophila, the novel homologous human and mouse genes with longer DNA/RNA helicase box (DEAD/DEAH box), named DDX36 and Ddx36 genes, respectively, were cloned as new members of the DEAD/H box superfamily. The predicted protein encoded by human DDX36 gene has a sequence identity of 37% and similarity of 58% with the MLE protein of Drosophila and 91% and 94% with the predicted protein encoded by mouse Ddx36 gene, respectively. Northern blotting of DDX36 shows a single strong signal of 3.8 kb in the hybridization pattern in human testis but no or very weak signal in other tissues. The DDX36 gene is mapped to chromosome 3q25.1-3q25.2, in which 26 exons and 25 introns have been identified. DDX36 and Ddx36 genes may be involved in sex development, spermatogenesis and male reproduction. Show less

Determination of the reticulocyte hemoglobin content (CHr) provides an early measure of functional iron deficiency because reticulocytes are the earliest erythrocytes released into blood and circulate for only 1 to 2 days. The CHr in 78 patients undergoing bone marrow examination was measured to assess its clinical utility for the diagnosis of iron deficiency. Twenty-eight patients were iron deficient, based on the lack of stainable iron in the aspirate. The diagnostic power of CHr is limited in patients with high mean cellular volume (MCV) or red cell disorders such as thalassemia. However, when patients with MCV more than 100 fL are excluded, receiver operator curve analysis of CHr, ferritin, transferrin saturation, and MCV demonstrates that CHr has the highest overall sensitivity and specificity of these peripheral blood tests for predicting the absence of bone marrow iron stores. Show less

Phospholipid (PL) from both dietary sources and biliary secretions may be important in the regulation of intestinal apolipoprotein (apo) synthesis. We previously demonstrated the up-regulation of apo A-I secretion by phosphatidylcholine (PC) in a newborn piglet intestinal epithelial cell line. We hypothesized that dietary PC increases small intestinal apo A-I synthesis in vivo in the newborn piglet. Two-day-old female swine were fed by gavage for 48 h. Diets consisted of a formula containing 51% of calories as triacylglycerol providing 180 kcal/kg/24 h. The experimental group (+PC, n = 7) received 1 g/L added soybean PC, and the control group (-PC, n = 7) received no added PC. At the end of the study period, jejunal apo A-I, B, and A-IV synthesis was measured, and apo A-I mRNA levels were quantitated. Jejunal mucosal PL content and serum lipids and apo B and A-I levels were measured. Jejunal apo A-I synthesis was almost twice as high in the +PC group as compared to the -PC group with no difference in apo A-I mRNA levels. Jejunal content of PL was higher in the +PC group than in the -PC group. There were no differences in jejunal apo B and A-IV synthesis or serum levels of lipids and apo-lipoproteins between the two groups. Dietary PC supplementation in newborn swine up-regulated jejunal apo A-I synthesis. Apo A-IV synthesis, which is sensitive to fatty acid flux, was not significantly increased, which suggests a specific effect of PC on apo A-I synthesis. Lumenal PC may be important in the regulation of intestinal apo A-I synthesis in the neonate. Show less

The infantile form of neuronal ceroid lipofuscinosis (NCL) has been well studied in Finland, where there is a high carrier frequency (1:70) for a single mutation in the causative gene, CLN1, or PPT. We have recently studied a group of 29 NCL subjects in the United States with palmitoyl-protein thioesterase (PPT) deficiency and described 19 different CLN1/PPT mutations in our population. In this report, we present a review of our previous findings, including a more detailed analysis of phenotype-genotype correlations, and present previously unpublished data concerning the clinical manifestations of the disorder in children of families with multiple affected members. Our studies indicate that about half of PPT-deficient patients in the United States are very similar to Finnish infants with INCL, but that a different mutation (R151X) accounts for 40% of U.S. alleles. The Finnish mutation (R122W) is rare in the United States. The other half of U.S. PPT-deficient patients develop symptoms after the age of 2 years, much later than Finnish patients. One common mutation (the "Scottish" allele, T75P) accounts for 13% of alleles and results in a juvenile-onset phenotype that is clinically indistinguishable from JNCL with CLN3 mutations. Other rare mutations were also associated with JNCL phenotypes, such as D79G and G250V. A preliminary expression study of two of these mutant enzymes supports the conclusion that juvenile-onset NCL (JNCL with GROD) is caused by missense mutations in the PPT gene that result in mutated enzymes with residual PPT enzyme activity. Show less

To study regulation of gamma-glutamylcysteine synthetase (GCS) heavy and light subunit gene expression in Müller cells under conditions of oxidative stress. Experiments were carried out with an SV40 transformed cell line (rMC-1) that exhibits the phenotype of rat retinal Müller cells. Endogenous glutathione levels were modified by treating cells with diethyl maleate (DEM), D,L-buthionine sulfoximine (BSO), or tert-butylhydroquinone (TBH). In other experiments, cells were grown in either high (28 mM) or normal (5.5 mM) glucose medium for 1 week to examine the effects of hyperglycemia. Cells were processed for reduced glutathione (GSH) measurement, RNA extraction, cell count, and, in some cases, lactate dehydrogenase activity. The steady state mRNA levels of GCS heavy and light subunits were measured by northern blot analysis using specific cDNA probes. Changes in mRNA levels were normalized to beta-actin or 18S rRNA. Treatment with DEM for 30 minutes depleted cell GSH to 20% to 30% of the normal value. GSH content recovered completely 6 hours after returning to normal medium. BSO treatment for 12 hours followed by a medium change for 6 hours resulted in a cell GSH level that was 26% that of untreated cells. If cells were left in BSO for 18 hours, however, GSH levels were reduced to < 1%. Treatment with TBH for 12 hours led to a 77% increase in cellular GSH level. Treatment with DEM, TBH, or BSO for 18 hours led to a significant induction of the mRNA level of the GCS subunits, regardless of glucose concentration in the medium. Shorter BSO treatment exerted no effect. Prolonged hyperglycemia resulted in 30% lower GSH level, 55% lower GCS heavy subunit, and 30% lower GCS light subunit mRNA levels. Oxidative stress induced the gene expression of GCS heavy and light subunits in Müller cells. The effect of BSO on mRNA levels correlated with the degree of GSH depletion. Prolonged hyperglycemia lowered GCS subunit mRNA and GSH levels. Show less

Williams syndrome (WS) is a contiguous gene deletion disorder caused by haploinsufficiency of genes at 7q11.23. We have shown that hemizygosity of elastin is responsible for one feature of WS, supravalvular aortic stenosis (SVAS). We have also implicated LIM-kinase 1 hemizygosity as a contributing factor to impaired visual-spatial constructive cognition in WS. However, the common WS deletion region has not been completely characterized, and genes for additional features of WS, including mental retardation, infantile hypercalcemia, and unique personality profile, are yet to be discovered. Here, we present a physical map encompassing 1.5 Mb DNA that is commonly deleted in individuals with WS. Fluorescence in situ hybridization analysis of 200 WS individuals shows that WS individuals have the consistent deletion interval. In addition, we identify three novel genes from the common deletion region: WS-betaTRP, WS-bHLH, and BCL7B. WS-betaTRP has four putative beta-transducin (WD40) repeats, and WS-bHLH is a novel basic helix-loop-helix leucine zipper (bHLHZip) gene. BCL7B belongs to a novel family of highly conserved genes. We describe the expression profile and genomic structure for each of these genes. Hemizygous deletion of one or more of these genes may contribute to developmental defects in WS. Show less