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Biomedical subjects

S Miao

Publications and source records attributed to S Miao.

28 records · Page 2Linked to original sources
PubMed1994

Identification of Glu340 as the active-site nucleophile in human glucocerebrosidase by use of electrospray tandem mass spectrometry.

Gaucher disease is an inherited lysosomal storage disorder caused by a deficiency of human acid beta-glucosidase (glucocerebrosidase). This enzyme is inactivated by the specific, mechanism-based enzyme inactivator 2-deoxy-2-fluoro-beta-D-glucopyranosyl fluoride, which functions by forming a stable 2-deoxy-2-fluoro-alpha-D-gluco-pyranosyl-enzyme intermediate. The key nucleophilic amino acid residue involved in formation of this intermediate was conclusively identified by tandem mass spectrometry as Glu340, and not Asp443 as thought previously. This was confirmed by site-directed mutagenesis. Identification, and mass determination, of the labeled peptide in a proteolytic hydrolysate involved detection of a collision-induced fragmentation reaction specific to the sugar-peptide linkage. Confirmation of the identity of the labeled peptide was obtained both by tandem mass spectrometric sequencing and by chemical degradation of the purified peptide. This method allowed the rapid, sensitive, and non-isotopic determination of an essential amino acid residue in a clinically important enzyme.

Amino Acid Sequence↗
PubMed1993

Proposed healing and consolidation mechanisms of rock salt revealed by ESEM.

The grain boundary healing behavior of crushed rock salt was mainly studied by employing the environmental scanning electron microscope (ESEM) to study the consolidation mechanism of rock salt backfill. Dedicated miniature round rock salt specimens were prepared for observation of the water trapping effect by using a cold stage in the ESEM to reach saturation conditions. Comparable high pressure pellets were prepared for measuring the crystal growth. Consolidation tests using materials made at different pressures and containing different moisture levels were conducted in order to construct the proposed mechanism. Direct observation of specimens in the ESEM resulted in viewing water trapped on the surface and the formation of a water meniscus between two particles. The concentration of brine at the grain boundary was observed as contributing to the amount of recrystallization. From aforementioned observations, a schematic drawing of the dissolution and recrystallization process may be redrawn. The amount of water therefore has a great effect on the consolidation of rock salt and is possibly due to the sliding, rotation, or crushing of the contact zone of the granular material. From such a study, tentative healing and consolidation mechanisms can be deduced.

Microscopy, Electron, Scanning↗
PubMed1993

Trehalose esters from the aspen fungus Hyphozyma lignicola.

Chemical investigation of the metabolites produced when a new fungus, Hyphozyma lignicola, isolated from blackgalls on aspen, was grown in malt extract liquid medium resulted in the isolation and identification of five trehalose esters 1-5, which are unusual fungal metabolites. The major compound is 3,6-di-O-acetyl-2-O-octadecanoyl-alpha,alpha-D-trehalose [2]. The structures were established by the analysis of nmr and fabms data in combination with chemical degradation.

Carbohydrate Sequence↗
PubMed1993

Role of the cyclic AMP response element in rat fibronectin gene expression.

Fibronectin expression is of considerable importance in normal and fibrotic liver. Plasma fibronectin levels are correlated with good prognosis in liver failure, and cellular fibronectin plays a crucial role in fibrogenesis. In this study, we observed that the H4II rat hepatoma cell line does not express fibronectin. Furthermore, a recombinant vector (pFGH) containing the promoter elements of the fibronectin gene showed no promoter function when transfected into this cell line. However, pFGH was actively expressed in L-cells and rat skin fibroblasts, cell types that express large amounts of endogenous fibronectin. To study the mechanisms regulating fibronectin expression, we evaluated the transcriptional regulatory elements of the rat fibronectin gene by mutational analysis and DNA-protein binding studies. Deletional mutation analysis showed that the sequences between positions -164 and -90 are essential for promoter activity. This region contains the consensus binding sites for CCAAT and the cyclic AMP-responsive element. Gel retardation assays demonstrated that although the binding activity to the CCAAT site at -140 was essentially the same as that in extracts from L-cells, hepatoma cells and rat livers, substantially greater amounts and different patterns of binding to the adjacent cyclic AMP-responsive element were observed in the extracts from the expressing L-cells and rat livers compared with those in the nonexpressing hepatoma cell nuclear extracts. Furthermore, mutagenesis of the cyclic AMP-responsive element site dramatically reduced promoter activity in transient transfection assays. The cyclic AMP-responsive element at position -160 appears to play an important role in the constitutive expression of the rat fibronectin gene.

Animals↗
PubMed1992

Detection of point mutations of the phenylalanine hydroxylase gene and prenatal diagnosis of phenylketonuria.

The known mutant alleles of the human phenylalanine hydroxylase (PAN) gene were analyzed in 25 phenylketonuria (PKU) families from North China by using polymerase chain reaction and allele-specific oligonucleotide dot blot hybridization techniques. The results showed that the six mutations analyzed accounted for 62% of all PKU genes. The three most frequent mutations were R243Q, R413P and Y204C. Seven prenatal gene diagnoses were carried out in 6 PKU families and were confirmed after birth or by examination of aborted materials.

Base Sequence↗
PubMed1990

Cloning and identification of a rabbit sperm membrane protein gene.

Antibodies raised against rabbit sperm membrane protein (rSMP-B) interacted with a rat testis cytosolic protein with an estimated molecular weight of 70 kD. The clone expressing rSMP-B was isolated by epitope selection from a rat testis lambda gt11 vector cDNA library. An Eco R1-cut 2.0 kb cDNA fragment encoding rSMP-B was identified. The cDNA fragment (RSD-1) was isolated, subcloned and restriction mapped. Dot hybridization analysis of mRNA prepared from human, rabbit and rat testes showed that the gene encoding rSMP-B is expressed in the testes of all three mammals.

Animals↗
PubMed1990

Nucleic acid sequence of cDNA (RSD-1) encoding a rabbit sperm membrane protein and structural properties of the encoded protein.

The nucleotide sequence of a 2.0 kb cDNA encoding a rabbit sperm tail membrane protein was determined using the chain termination method. Analysis was performed using Sequenase and Klenow enzymes on the target sequence in an M13mp18/19 cloning system. The open reading frame consisted of 438 bp encoding 146 amino acids of the protein, with a calculated Mr of 15507. The hydrophobic amino acid content was 34.9%, and pI was in the vicinity of 5.8.

Amino Acid Sequence↗
PubMed1990

Inhibition of zygote formation and embryo development in mice immunized with monoclonal antisperm antibodies.

Passive immunization of female mice by the intraperitoneal administration of ascitic fluids containing monoclonal antisperm antibodies blocked the development of mouse zygotes to morulae and blastocysts when cultured in vitro. Radioiodinated YWK-I monoclonal antibodies were prepared and administered intraperitoneally to female mice. Significant radioactivity was found in washes of the oviductal lumens. The results suggest that antisperm antibodies block fertilization and may have a deleterious effect on early developing embryos.

Animals↗
PubMed1977

Computer-assisted pathology encoding and reporting system (CAPER).

An on-line computer-assisted pathology encoding and reportying system (CAPER) has been developed by the Department of Pathology and Laboratory of Computer Science of the Massachusetts General Hospital for a department of surgical pathology that processes more than 25,000 specimens yearly. CAPER performs clerical functions, including the accessioning of specimens, monitoring their state of completion, production of log books, billing, statistics, and transfer of diagnoses to other hospital departments. It also permits instantaneous display of all diagnoses rendered within two years, printout within 24 hours of all older diagnoses for any patient, and retrieval of all specimens with any given diagnosis, further defined by any data item (e.g., age) stored in the computer file.

Computers↗