PubMed Health⌕ Search

Biomedical subjects

D S Zhang

Publications and source records attributed to D S Zhang.

At least 19 recordsLinked to original sources
PubMed2005

Characterization and mapping of Rpi1, a gene that confers dominant resistance to stalk rot in maize.

The maize inbred lines 1145 (resistant) and Y331 (susceptible), and the F(1), F(2) and BC(1)F(1) populations derived from them were inoculated with the pathogen Pythium inflatum Matthews, which causes stalk rot in Zea mays. Field data revealed that the ratio of resistant to susceptible plants was 3:1 in the F(2) population, and 1:1 in the BC(1)F(1)population, indicating that the resistance to P. inflatum Matthews was controlled by a single dominant gene in the 1145xY331 cross. The gene that confers resistance to P. inflatum Matthews was designated Rpi1 for resistance to P. inflatum) according to the standard nomenclature for plant disease resistance genes. Fifty SSR markers from 10 chromosomes were first screened in the F(2) population to find markers linked to the Rpi1 gene. The results indicated that umc1702 and mmc0371 were both linked to Rpi1, placing the resistance gene on chromosome 4. RAPD (randomly amplified polymorphic DNA) markers were then tested in the F(2)population using bulked segregant analysis (BSA). Four RAPD products were found to show linkage to the Rpi1 gene. Then 27 SSR markers and 8 RFLP markers in the region encompassing Rpi1 were used for fine-scale mapping of the resistance gene. Two SSR markers and four RFLP markers were linked to the Rpi1 gene. Finally, the Rpi1 gene was mapped between the SSR markers bnlg1937 and agrr286 on chromosome 4, 1.6 cM away from the former and 4.1 cM distant from the latter. This is the first time that a dominant gene for resistance to maize stalk rot caused by P. inflatum Matthews has been mapped with molecular marker techniques.

Chromosome Mapping↗
PubMed2004

A chromosome bin map of 16,000 expressed sequence tag loci and distribution of genes among the three genomes of polyploid wheat.

Because of the huge size of the common wheat (Triticum aestivum L., 2n = 6x = 42, AABBDD) genome of 17,300 Mb, sequencing and mapping of the expressed portion is a logical first step for gene discovery. Here we report mapping of 7104 expressed sequence tag (EST) unigenes by Southern hybridization into a chromosome bin map using a set of wheat aneuploids and deletion stocks. Each EST detected a mean of 4.8 restriction fragments and 2.8 loci. More loci were mapped in the B genome (5774) than in the A (5173) or D (5146) genomes. The EST density was significantly higher for the D genome than for the A or B. In general, EST density increased relative to the physical distance from the centromere. The majority of EST-dense regions are in the distal parts of chromosomes. Most of the agronomically important genes are located in EST-dense regions. The chromosome bin map of ESTs is a unique resource for SNP analysis, comparative mapping, structural and functional analysis, and polyploid evolution, as well as providing a framework for constructing a sequence-ready, BAC-contig map of the wheat genome.

Chromosome Mapping↗
PubMed2004

Processing dewatered sewage sludge using electrokinetic technology.

High content of heavy metals and presence of pathogens in the dewatered sewage sludge have been the main obstacles for land application of sewage sludge-made fertilizer. The aim of this study was to examine the effects of the innovative electrokinetic (EK) technology on removal of heavy metals from sewage sludge, on the reduction of pathogens, and on sludge chemical characteristics. The results showed that the removal efficiencies for Zn, Cu, Ni, Cr, As and Pb were 94.9%, 95.4%, 89.7%, 67.8%, 31.2% and 18.7%, respectively. Acidification pretreatment of the dewatered sludge for 29 h decreased the content of heterotrophic bacteria from 1.5 x 10(8) c.f.u./g of wet sludge to 1.1 x 10(4) c.f.u./g of wet sludge. Although the initial content of total coliforms and fecal coliforms in sewage sludge were 5.8 x 10(5) c.f.u./g of wet sludge and 4.0 x 10(5) c.f.u./g of wet sludge, respectively, no viable cells were detected. Minor losses of K and N were detected, but the loss of P was found to be significant in EK treated sewage sludge. The treated sludge was technically considered as very stable based on the carbon dioxide evolution rate.

Bioreactors↗
PubMed2003

Genetic analysis and molecular mapping of maize (Zea mays L.) stalk rot resistant gene Rfg1.

One single pathogen Fusarium graminearum Schw. was inoculated to maize inbred lines 1,145 (Resistant) and Y331 (Susceptive), and their progenies of F(1), F(2) and BC(1)F(1) populations. Field statistical data revealed that all of the F(1) individuals were resistant to the disease and that the ratio of resistant plants to susceptive plants was 3:1 in the F(2) population, and 1:1 in the BC(1)F(1 )population. The results revealed that a single dominant gene controls the resistance to F. graminearum Schw. The resistant gene to F. graminearum Schw. was denominated as Rfg1 according to the standard principle of the nomenclature of the plant disease resistant genes. RAPD (randomly amplified polymorphic DNA) combined with BSA (bulked segregant analysis) analysis was carried out in the developed F(2) and BC(1)F(1 )populations, respectively. Three RAPD products screened from the RAPD analysis with 820 Operon 10-mer primers showed the linkage relation with the resistant gene Rfg1. The three RAPD amplification products (OPD-20(1000), OPA-04(1100) and OPY-04(900)) were cloned and their copy numbers were determined. The results indicated that only OPY-04(900) was a single-copy sequence. Then, OPY-04(900) was used as a probe to map the Rfg1 gene with a RIL F(7) mapping population provided by Henry Nguyen, which was developed from the cross "S3xMo17". Rfg1 was primarily mapped on chromosome 6 between the two linked markers OPY-04(900) and umc21 (Bin 6.04-6.05). In order to confirm the primary mapping result, 25 SSR (simple sequence repeat) markers and six RFLP (restriction fragment length polymorphism) markers in the Rfg1 gene-encompassing region were selected, and their linkage relation with Rfg1 was analyzed in our F(2) population. Results indicated that SSR marker mmc0241 and RFLP marker bnl3.03 are flanking the Rfg1 gene with a genetic distance of 3.0 cM and 2.0 cM, respectively. This is the first time to name and to map a single resistant gene of maize stalk rot through a single pathogen inoculation and molecular marker analysis.

Chromosome Mapping↗
PubMed2001

Myosin-VIIb, a novel unconventional myosin, is a constituent of microvilli in transporting epithelia.

Mouse myosin-VIIb, a novel unconventional myosin, was cloned from the inner ear and kidney. The human myosin-VIIb (HGMW-approved symbol MYO7B) sequence and exon structure were then deduced from a human BAC clone. The mouse gene was mapped to chromosome 18, approximately 0.5 cM proximal to D18Mit12. The human gene location at 2q21.1 was deduced from the map location of the BAC and confirmed by fluorescence in situ hybridization. Myosin-VIIb has a conserved myosin head domain, five IQ domains, two MyTH4 domains coupled to two FERM domains, and an SH3 domain. A phylogenetic analysis based on the MyTH4 domains suggests that the coupled MyTH and FERM domains were duplicated in myosin evolution before separation into different classes. Myosin-VIIb is expressed primarily in kidney and intestine, as shown by Northern and immunoblot analyses. An antibody to myosin-VIIb labeled proximal tubule cells of the kidney and enterocytes of the intestine, specifically the distal tips of apical microvilli on these transporting epithelial cells.

Amino Acid Sequence↗
PubMed2000

[Functional evaluation of electrical-injury nerve using somatosensory evoked potential technique].

OBJECTIVE: To investigate the characteristics and the pathologic classification of electrical-injury nerve using somatosensory evoked potential(SEP) technique. METHODS: SEP were detected and evaluated in 12 cases with electrical-injury nerve during operation, electrical stimulation was commenced from distal side of nerve where the structure of nerve looks normal under operating microscope, up to proximal side until evoking out a stable SEP predeterminate virtual value. Pathological examination and the following functional evaluation were compared with the values of SEP. RESULTS: At the site of nerve looking normal under operating microscope, perineurium appears normal or slightly thicken. But there are obvious fibrosis and fibrotic proliferation between fascicular and intrafascicular. Vessel plexus is not seen. At SEP stabilizely evoked site, nervous construction is normal, there are visible interfascicular vessel plexus and connective tissue appears loose. Comparing SEP values with pathological section, amplitude and latency of SEP is positively correlative with the quality of nerve. Eight cases repaired with SEP technique to select the anastomosis site for nerve transplantation were followed up, two-point discrimination reached grade III (America hand surgery association criterion) within 62.5% cases. CONCLUSION: SEP technique is valuable method for functional evaluation of electrical- injury nerve which has a complicated pathology. The pathology of electrical-injury nerve can be classified into 4 types, type A: fibrosis of nerve; type B: nerve looking normal under operation microscope, perineurium appears thicken, and there are obvious fibrosis and fibrotic proliferation between fascicular and intrafascicular, vessel plexus is rarely to see; type C: nerve looks normal, lymphocyte infiltration exists and it is obvious that there are many physalis-like, retrogressive construction in the section; type D: nervous construction is normal, there are visible interfascicular vessel plexus, and connective tissue appears loose, SEP always can be stably evoked.

Adolescent↗
PubMed1999

[Establishment of the animal models of mandibular distraction osteogenesis].

OBJECTIVE: To establish the animal models of mandibular distraction osteogenesis in rabbits and study its osteogenetic mechanism. METHODS: The right mandibles just anterior to the first molars of 12 rabbits were performed osteotomies, and the mandibles were positioned with distractors. The left mandibles were control group without operation. After 1 week, the distractors were stretched 0.9 mm every day for 10 days progressively. One day, 2, 4, 8 weeks after distraction, the mandibles were studied with gross measurement, X-ray, and histological examination. RESULTS: The right mandible were lengthened 8.3 mm on average without bone nonunion and deformity healing. It was observed that the gaps between the distracted bone edges were first occupied by fibrous tissue. Two weeks after distraction, it was found that the gaps were bridged by callus in X-ray, the new bone and the normal bone could not be differentiated clearly after 8 weeks. In histological sections, there were collagen bundles in early distraction, then those collagen bundles were calcificated and become trabeculaes. No Cartilage was found during distraction. CONCLUSION: It suggests that the rabbit mandible can be lengthened by distraction osteogenesis, and the new bone is formed by intramembranous ossification.

Animals↗
PubMed1996

HLA typing in patients with ocular manifestations of Stevens-Johnson syndrome.

BACKGROUND: Stevens-Johnson syndrome (SJS) is an acute, self-limited, inflammatory disorder of the skin and mucous membranes. With ocular involvement, SJS has been associated with the class I human leukocyte antigen (HLA)-Bw44. This study examined HLA class II associations in patients with SJS with ocular involvement to help identify possible molecular genetic mechanisms underlying disease susceptibility/resistance. METHODS: Twenty-three white patients with ocular complications secondary to SJS had HLA class II typing performed using polymerase chain reaction-based molecular techniques. Genotype frequency was compared with results obtained from 175 control subjects. RESULTS: HLA-DQB1*0601 was present in four (17%) patients with SJS and in five (3%) control subjects (P < 0.05; relative risk = 7.2). There was no association with HLA-DQB1*0301, which previously has been been strongly associated with recurrent erythema multiforme. None of the class II antigens tested appeared to offer a protective effect against the development of disease. CONCLUSION: HLA-DQB1*0601 was found in a significantly disproportionate number of white patients with SJS and ocular complications. The presence of this allele may confer an increased risk for the development of SJS with ocular complications and provides further evidence for an underlying immunogenetic susceptibility to the development of this disease.

Adult↗
PubMed1995

Detection in human blood platelets of sialyl Lewis X gangliosides, potential ligands for CD62 and other selectins.

Activated platelets are known to express P-selectin, a lectin-like adhesion receptor (CD62), through which they bind to sialyl Lewis X (sLex) ligands displayed on the membranes of leukocytes. To determine whether direct platelet-platelet interactions via P-selectin/sLex interactions are also possible, we have examined the ganglioside extract of human blood platelets for the presence of sLex ligands. Using the sensitive method of high-performance thin-layer chromatography (HPTLC)-immunostaining with the monoclonal antibody (mAb) CSLEX or with sialidase followed by mAbs MC480 or PM81, eight sLex bands were demonstrated at Rf 0.01, 0.03, 0.05, 0.06, 0.08, 0.10, 0.14 and 0.21 in the solvent 45:55:10 chloroform-methanol-aqueous 0.02% CaCl2. The sensitivity of all eight bands to sialidase or endoglycoceramidase confirmed that they were gangliosides. Comparison of the HPTLC mobilities and densities of platelet bands with those from five other human tissues (granulocytes, monoblasts, kidney, aortic endothelium and erythrocytes) in three different solvents revealed three major bands associated with platelets: 3 (Rf0.03), 6 (0.08) and 14 (0.21). Platelet bands were demonstrated not to have resulted from granulocyte contamination. Partial purification of platelet sLex gangliosides by high-performance liquid chromatography and their reaction with 14 oligosaccharide-specific mAbs (FH4, FH5, LM112-161, LM119-181, A5, 1B2, BR55-2, BE2, ES4, MC631, MH04, SH34, P001 and MC813-70) revealed that band 6 is a multifucosylated neolacto ganglioside and band 14 is a branched, disialo neolacto fucoganglioside. Platelet band 3 combined the features of both bands 6 and 14, and reacted differently than granulocyte band 3. These partial structures resemble gangliosides associated with adhesion in other cell systems. It is concluded that platelets express tissue-specific sLex gangliosides (sLex ligands). Thus, it is possible that platelet-platelet binding may be mediated at least partially through P-selectin/sLex interactions, especially after platelet activation.

Blood Platelets↗
PubMed1994

[Percutaneous catheter drainage for post-traumatic perinephric urinoma].

From June 1989 to April 1992, 5 patients with post-traumatic perinephric urinoma were treated by using percutaneous catheter drainage. The urinoma disappeared and the renal function restored in all the 5 patients 18-27 days (average 21.8 days) after continual drainage. Follow-up for 1-4 (averaging 2-6 years) years showed non-recurrence of the urinoma in all the 5 patients. The procedure is characterized by less distress and economical to the patients. It can keep the kidneys intact. The pathogenesis, pathology, diagnosis and treatment are discussed along with a review of the literature.

Adolescent↗
PubMed1993

[Effect of intracerebroventricular injection of N-methyl-D-aspartate on learning and memory in mice].

In one trial passive avoidance response in mice, the effect of N-methyl-D-aspartate (NMDA) on acquisition, consolidation and retrieval of memory were observed after icv administration of 10 ng, 1 ng or 0.1 ng/mouse. The results showed that NMDA 10 ng/mouse could promote the consolidation of memory in step-down test and 1 ng/mouse could promote the retrieval of memory in step-through test. NMDA 1 ng/mouse significantly improved the retrieval impairment induced by 30% alcohol and the consolidation impairment induced by NaNO2 in step-down and step-through tests. The effect of NMDA on memory was antagonized by NMDA receptor antagonist, AP5. These results provide direct evidence for the action of NMDA subtype of glutamate receptor on memory.

Animals↗
PubMed1993

Surgical correction of hypertelorism. Report of 40 cases.

Forty patients with hypertelorism seen in the past 16 years were reviewed retrospectively. Combined intra- and extracranial surgical approach was used for 37 severe and moderate cases and subcranial approach (U-osteotomy) for 3 moderate cases. Gratifying results were obtained in patients with different types of hypertelorism by a multidisciplinary team. Complications were also reviewed. Of the 37 cases of intra- and extracranial corrections, 1 died, 4 had cerebrospinal fluid leakage and 4 had keratitis. No seizure, cerebral edema, meningitis, blindness, and ptosis occurred in this series. The average age was 13 years and two months. Operating time averaged 6 hours and 50 minutes. Hypertelorism was mostly attributable to craniofacial cleft, craniosynostosis, frontoethmoidal meningoencephalocele, frontonasal fibrous dysplasia, and trauma. Satisfactory esthetic appearance was achieved in most of the cases.

Adolescent↗