Biomedical subjects

G Jiang

Publications and source records attributed to G Jiang.

At least 37 records · Page 2Linked to original sources

PubMed2003

Chitosan-coated liposomes: characterization and interaction with leuprolide.

The objective of the present work was to investigate the effect of chitosan concentration and lipid type on the characteristics of chitosan-coated liposomes and their interactions with leuprolide. Liposomes from lipid of high purity and low purity were prepared and coated by chitosan. Physical properties, drug entrapment efficiency, and stability upon dilution were respectively compared. Results showed that the particle size increment of liposomes from low purity lipid was larger than that from high purity lipid, indicating a thicker coating layer. The high zeta potential of particles from low purity lipid was thought to play an important role in the resistance to flocculation. As to particles from high purity lipid, polymer bridging caused flocculation at low polymer concentration while at high concentration, the adsorbed chitosan molecule led to steric stabilization. Drug entrapment efficiency decreased as chitosan was added to liposomes, showing the disturbance of bilayers. Upon dilution, the leakage of leuprolide from low purity liposomes was larger than that from high purity liposomes. In conclusion, low purity lipid possessed more negative charge and formed thicker adsorptive layer by stronger electrostatic attraction with chitosan. The interaction between chitosan and the polar head groups on the surface of phospholipid bilayers may interfere with leuprolide entrapped in liposomes and result in the leakage of leuprolide.

Chitin↗

PubMed2003

Stimulation of Na,K-ATPase by low potassium is dependent on transferrin.

We took advantage of the fact that confluent MDCK cells can survive in a serum-free medium for several days to examine whether the upregulation of Na,K-ATPase by low K+ required serum. We found that serum was essential for low K+ to induce an increase in the cell surface Na,K-ATPase molecular number as quantified by ouabain binding assays. Further analyses identified that transferrin, not EGF or IGF-1, could simulate the effect of serum. Moreover, transferrin was also required for low-K(+)-induced increases in al-subunit promoter activity, al- and el-subunit protein abundance of the Na,K-ATPase. In the presence of transferrin, low K+ enhanced cellular uptake of iron. Inhibition of intracellular iron activity by deferoxamine (40 microM) abrogated the effect of low K+ on the Na,K-ATPase. Like deferoxamine, catalase (100 U/ml) also ablated the effect of low K+. We conclude that stimulation of the Na,K-ATPase by low K+ is dependent on transferrin. The effect of transferrin is mediated by increased iron transport and reactive oxygen species activity.

Animals↗

PubMed2003

Visual identification of vertebral fractures in osteoporosis using morphometric X-ray absorptiometry.

Visual identification of vertebral fractures from spinal radiographs (visual XR) makes use of the reader's expertise in ruling out non-fracture deformities or normal variants. Scan images of the spine acquired by DXA may be analyzed quantitatively (morphometric X-ray absorptiometry [quantitative MXA]) or visually (visual MXA). The aims of this study were to compare visual and quantitative MXA with visual XR for the identification of vertebral fractures. Spinal radiographs and MXA scans were acquired at baseline and 1 year in 70 women referred with osteoporosis. These were assessed visually by two expert readers (observer A, a radiologist; observer B, a physician with expertise in osteoporosis) for evidence of prevalent and incident vertebral fractures. Observer C (a radiographer with expertise in vertebral morphometry) performed visual and quantitative assessments of the MXA scans. Visual assessment of spinal radiographs by observer A was used as the gold standard for comparison of methods. Sensitivity for the identification of prevalent fractures by MXA was best for visual MXA by observer A (92%), whereas quantitative MXA had the lowest sensitivity (82%). Specificity was >90% for both visual and quantitative MXA. Kappa scores for agreement for identification of prevalent fractures between visual XR (observer A) and visual MXA (all three observers), and between visual XR and visual MXA performed by reader B were similar (kappa = 0.85-0.87). Agreement with visual XR performed by observer A was slightly lower for quantitative MXA (kappa = 0.77). Interobserver agreement between the two expert readers (observers A and B) was the same for both visual XR and visual MXA (kappa = 0.86). Seven incident vertebral fractures were identified in four patients at follow-up. All four patients were identified by visual MXA, and three patients were identified by quantitative MXA. Observers A and B identified all seven incident fractures by visual MXA, and observer C missed one fracture that was also missed by quantitative MXA. An incident fracture of vertebra T6 was excluded from analysis by quantitative MXA because of poor image quality. We conclude that visual identification of vertebral fractures from MXA scans is superior to quantitative assessment. Used as a screening tool for conventional radiography, this approach could help reduce the radiation dose to the patient in the diagnosis and monitoring of osteoporosis.

Absorptiometry, Photon↗

PubMed2002

Comparison of computer-based information support to clinical research in Chinese and Japanese hospitals: a postal survey of clinicians' views.

OBJECTIVES: The objectives of this research are to examine the current situation of computer-based information support of clinical research in hospitals and to determine the expectations of clinicians toward clinical research support functions of hospital information systems (HISs) in both China and Japan. METHODS: 172 clinicians from 42 major hospitals in China (2 groups), and 568 clinicians from 79 university hospitals in Japan (2 groups), were surveyed by postal questionnaire during July and August, 1999. The Kruskal-Wallis test was performed to analyze the differences among the groups. RESULTS: The total response rate was 66.9%. The result shows that 94.8% of the Japanese clinicians, 3.5 times more than those in China, use computers almost every day. High significance was shown for the frequency of non-HIS based information resources used by clinicians between China and Japan (p < 0.001), whereas no significance for the frequency of HIS use by clinicians between the China I and Japan I groups (p = 0.725) was found. 33.3% clinicians in China thought they could obtain 30-50% of the necessary patient data for clinical research from the HIS, about 2 times more than in Japan (p = 0.009). CONCLUSIONS: Although the degree of computer involvement among clinicians in Japan is much higher than in China, the computer-based hospital information systems have not been developed well for supporting clinical research in both countries. The clinicians expect comprehensive computerized patient records (CPRs) and full use of patient related information in the existing HISs to support their clinical research.

Attitude to Computers↗

PubMed2001

DNA methyltransferase 3B mutations linked to the ICF syndrome cause dysregulation of lymphogenesis genes.

ICF (immunodeficiency, centromeric region instability and facial anomalies) is a recessive disease caused by mutations in the DNA methyltransferase 3B gene (DNMT3B). Patients have immunodeficiency, chromosome 1 (Chr1) and Chr16 pericentromeric anomalies in mitogen-stimulated lymphocytes, a small decrease in overall genomic 5-methylcytosine levels and much hypomethylation of Chr1 and Chr16 juxtacentromeric heterochromatin. Microarray expression analysis was done on B-cell lymphoblastoid cell lines (LCLs) from ICF patients with diverse DNMT3B mutations and on control LCLs using oligonucleotide arrays for approximately 5600 different genes, 510 of which showed a lymphoid lineage-restricted expression pattern among several different lineages tested. A set of 32 genes had consistent and significant ICF-specific changes in RNA levels. Half of these genes play a role in immune function. ICF-specific increases in immunoglobulin (Ig) heavy constant mu and delta RNA and cell surface IgM and IgD and decreases in Ig(gamma) and Ig(alpha) RNA and surface IgG and IgA indicate inhibition of the later steps of lymphocyte maturation. ICF-specific increases were seen in RNA for RGS1, a B-cell specific inhibitor of G-protein signaling implicated in negative regulation of B-cell migration, and in RNA for the pro-apoptotic protein kinase C eta gene. ICF-associated decreases were observed in RNAs encoding proteins involved in activation, migration or survival of lymphoid cells, namely, transcription factor negative regulator ID3, the enhancer-binding MEF2C, the iron regulatory transferrin receptor, integrin beta7, the stress protein heme oxygenase and the lymphocyte-specific tumor necrosis factor receptor family members 7 and 17. No differences in promoter methylation were seen between ICF and normal LCLs for three ICF upregulated genes and one downregulated gene by a quantitative methylation assay [combined bisulfite restriction analysis (COBRA)]. Our data suggest that DNMT3B mutations in the ICF syndrome cause lymphogenesis-associated gene dysregulation by indirect effects on gene expression that interfere with normal lymphocyte signaling, maturation and migration.

Cell Line↗

PubMed2001

High-level erythroid-specific gene expression in primary human and murine hematopoietic cells with self-inactivating lentiviral vectors.

Use of oncoretroviral vectors in gene therapy for hemoglobinopathies has been impeded by low titer vectors, genetic instability, and poor expression. Fifteen self- inactivating (SIN) lentiviral vectors using 4 erythroid promoters in combination with 4 erythroid enhancers with or without the woodchuck hepatitis virus postregulatory element (WPRE) were generated using the enhanced green fluorescent protein as a reporter gene. Vectors with high erythroid-specific expression in cell lines were tested in primary human CD34(+) cells and in vivo in the murine bone marrow (BM) transplantation model. Vectors containing the ankyrin-1 promoter showed high-level expression and stable proviral transmission. Two vectors containing the ankyrin-1 promoter and 2 erythroid enhancers (HS-40 plus GATA-1 or HS-40 plus 5-aminolevulinate synthase intron 8 [I8] enhancers) and WPRE expressed at levels higher than the HS2/beta-promoter vector in bulk unilineage erythroid cultures and individual erythroid blast-forming units derived from human BM CD34(+) cells. Sca1(+)/lineage(-) Ly5.1 mouse hematopoietic cells, transduced with these 2 ankyrin-1 promoter vectors, were injected into lethally irradiated Ly5.2 recipients. Eleven weeks after transplantation, high-level expression was seen from both vectors in blood (63%-89% of red blood cells) and erythroid cells in BM (70%-86% engraftment), compared with negligible expression in myeloid and lymphoid lineages in blood, BM, spleen, and thymus (0%-4%). The I8/HS-40-containing vector encoding a hybrid human beta/gamma-globin gene led to 43% to 113% human gamma-globin expression/copy of the mouse alpha-globin gene. Thus, modular use of erythroid-specific enhancers/promoters and WPRE in SIN-lentiviral vectors led to identification of high-titer, stably transmitted vectors with high-level erythroid-specific expression for gene therapy of red cell diseases.

Animals↗

PubMed2001

Return to fertility after extended chemical castration with a GnRH antagonist.

BACKGROUND: Antagonistic analogues of GnRH for the treatment of prostate cancer may be used clinically in persons for whom return to fertility after such treatment is important or desirable. The purpose of this study was, therefore, to evaluate the effects of a long term treatment with orntide, a GnRH antagonist, on testosterone levels and fertility in male rats. METHODS: Two groups of male rats received either 120-day orntide microspheres (8.8 mg orntide/kg/120 days) or vehicle alone (control group). Serum orntide and testosterone levels in both groups were monitored at certain intervals for 9 months from the initiation of treatment. After recovery of normal serum testosterone levels in the treated animals, each rat was housed with two proven breeder, but drug-naive, females. RESULTS: All mates of treated rats achieved pregnancy as rapidly as the mates of control rats although two of the control rats did not sire a litter with either female and one sired only one litter. The mean size of the litters of treated (12.3 offspring per litter) and control (10.6 offspring per litter) were similar. All offspring were grossly normal morphologically and behaviorally during the time to weaning. CONCLUSIONS: These results suggest that lack of fertility due to testosterone suppression is reversible after cessation of treatment with this GnRH antagonist.

Animals↗

PubMed2001

Five unique compounds: xyloketals from mangrove fungus Xylaria sp. from the South China Sea coast.

Five unique metabolites, xyloketals A (1), B (2), C (3), D (4), and E (5), and the known 6 were isolated from mangrove fungus Xylaria sp. (no. 2508), obtained from the South China Sea. The structures of these compounds were elucidated by spectroscopic and X-ray diffraction experiments. Xyloketal A is a ketal compound with a C(3) symmetry and xyloketals B-E are its analogues. It was found that xytoketal C slowly rearranged to xytoketal B in DMSO-d(6)() solution at room temperature. Xyloketal A exhibited the activity of inhibiting acetylcholine esterase.

Acetylcholinesterase↗

PubMed2001

ABL1 promoter methylation can exist independently of BCR-ABL transcription in chronic myeloid leukemia hematopoietic progenitors.

Formation of the hybrid BCR-ABL gene is responsible for >95% of chronic myeloid leukemia (CML). The alternative, downstream ABL promoter (Pa), which is usually retained in this chimeric oncogene, was reported to be methylated in many CML patients, but there has been controversy as to whether this methylation is a frequent change in bone marrow (BM) in early chronic phase (CP) or only past this stage. Also, the relevance of Pa promoter methylation to BCR-ABL expression in CML is unclear. We examined methylation of the ABL Pa promoter in uncultured BM samples and in colonies derived from their hematopoietic precursor cells by bisulfite and PCR-based assays (combined bisulfite restriction analysis and methylation-specific PCR). BM from seven CP CML patients at diagnosis had about 20-60% of the copies of the ABL Pa promoter methylated. No Pa methylation was detected in normal BMs or colonies derived from them. In contrast, most colonies from CP CML patients had Pa methylation. Surprisingly, 18-49% of the CML-derived colonies with this methylation reproducibly had no detectable BCR-ABL RNA on nested reverse transcription-PCR. Furthermore, the percentage of BCR-ABL RNA-positive colonies was almost same among the colonies not displaying Pa methylation as among the colonies in which this methylation was found. We conclude that ABL Pa methylation is often an early marker of CML in hematopoietic precursors and in total mononuclear BM cells but that it is not associated with an increased frequency of BCR-ABL RNA-positive cells. This methylation might be emblematic of cancer-associated hypermethylation elsewhere in the genome with the consequent silencing of tumor suppressor genes seen in many malignancies.

Adult↗

PubMed2001

Inhibition of Na,K-ATPase activates PI3 kinase and inhibits apoptosis in LLC-PK1 cells.

In the present study we used LLC-PK1 cells, a porcine renal proximal tubular cell line, to investigate whether PI3 kinase activation was involved in the anti-apoptotic effect of ouabain, a specific inhibitor of Na,K-ATPase. Apoptosis was induced by actinomycin D (Act D, 5 microM) and assessed by appearance of hypodiploid nuclei and DNA fragmentation. Ouabain attenuated Act D-induced apoptotic response in a dose-dependent manner. Incubation in a low K(+) medium (0.1 mM) which is another way to decrease Na,K-ATPase activity also had anti-apoptotic effect. Both ouabain and low K(+) medium increased the PI3 kinase activity in p85 immunoprecipitates. Ouabain, as well as incubation in the low K(+) medium, also increased the phosphorylation of Akt. Inhibition of PI3 kinase by either wortmannin or LY294002 reversed the cytoprotective effect of ouabain. These data together indicate that inhibition of Na,K-ATPase activates PI3 kinase in LLC-PK1 cells which could then exert the cytoprotective effect.

Animals↗

PubMed2001

Dimerization of receptor protein-tyrosine phosphatase alpha in living cells.

BACKGROUND: Dimerization is an important regulatory mechanism of single membrane-spanning receptors. For instance, activation of receptor protein-tyrosine kinases (RPTKs) involves dimerization. Structural, functional and biochemical studies suggested that the enzymatic counterparts of RPTKs, the receptor protein-tyrosine phosphatases (RPTPs), are inhibited by dimerization, but whether RPTPs actually dimerize in living cells remained to be determined. RESULTS: In order to assess RPTP dimerization, we have assayed Fluorescence Resonance Energy Transfer (FRET) between chimeric proteins of cyan- and yellow-emitting derivatives of green fluorescent protein, fused to RPTPalpha, using three different techniques: dual wavelength excitation, spectral imaging and fluorescence lifetime imaging. All three techniques suggested that FRET occurred between RPTPalpha -CFP and -YFP fusion proteins, and thus that RPTPalpha dimerized in living cells. RPTPalpha dimerization was constitutive, extensive and specific. RPTPalpha dimerization was consistent with cross-linking experiments, using a non-cell-permeable chemical cross-linker. Using a panel of deletion mutants, we found that the transmembrane domain was required and sufficient for dimerization. CONCLUSIONS: We demonstrate here that RPTPalpha dimerized constitutively in living cells, which may be mediated by the transmembrane domain, providing strong support for the model that dimerization is involved in regulation of RPTPs.

Cross-Linking Reagents↗

PubMed2001

GnRH antagonists: a new generation of long acting analogues incorporating p-ureido-phenylalanines at positions 5 and 6.

A series of antagonists of gonadotropin-releasing hormone (GnRH) of the general formula Ac-D2Nal-D4Cpa-D3Pal-Ser-4Aph/4Amf(P)-D4Aph/D4Amf(Q)-Leu-ILys-Pro-DAla-NH2 was synthesized, characterized, and screened for duration of inhibition of luteinizing hormone release in a castrated male rat assay. Selected analogues were tested in a reporter gene assay (IC50 and pA2) and an in vitro histamine release assay. P and Q contain urea/carbamoyl functionalities designed to increase potential intra- and intermolecular hydrogen bonding opportunities for structural stabilization and peptide/receptor interactions, respectively. These substitutions resulted in analogues with increased hydrophilicity and a lesser propensity to form gels in aqueous solution than azaline B [Ac-D2Nal-D4Cpa-D3Pal-Ser-4Aph(Atz)-D4Aph(Atz)-Leu-ILys-Pro-DAla-NH2 with Atz = 3'-amino-1H-1',2',4'-triazol-5'-yl, 5], and in some cases they resulted in a significant increase in duration of action after subcutaneous (s.c.) administration. Ac-D2Nal-D4Cpa-D3Pal-Ser-4Aph(L-hydroorotyl)-D4Aph(carbamoyl)-Leu-ILys-Pro-DAla-NH2 (acetate salt is FE200486) (31) and eight other congeners (20, 35, 37, 39, 41, 45-47) were identified that exhibited significantly longer duration of action than acyline [Ac-D2Nal-D4Cpa-D3Pal-Ser-4Aph(Ac)-D4Aph(Ac)-Leu-ILys-Pro-DAla-NH2] (6) when administered subcutaneously in castrated male rats at a dose of 50 microg in 100 microL of phosphate buffer. No correlation was found between retention times on a C18 reverse phase column using a triethylammonium phosphate buffer at pH 7.0 (a measure of hydrophilicity) or affinity in an in vitro human GnRH report gene assay (pA2) and duration of action. FE200486 was selected for preclinical studies, and some of its properties were compared to those of other clinical candidates. In the intact rat, ganirelix, abarelix, azaline B, and FE200486 inhibited plasma testosterone for 1, 1, 14, and 57 days, respectively, at 2 mg/kg s.c. in 5% mannitol (injection volume = 20 microL). Based on the information that 31, 33, 35 and 37 were significantly shorter acting than acyline or azaline B after intravenous administration (100 microg/rat), we surmised that the very long duration of action of the related FE200486 (for example) was likely due to unique physicochemical properties such as solubility in aqueous milieu, comparatively low propensity to form gels, and ability to diffuse at high concentrations in a manner similar to that described for slow release formulations of peptides. Indeed, in rats injected s.c. with FE200486 (2 mg/kg), plasmatic concentrations of FE200486 remained above 5 ng/mL until day 41, and the time after which they dropped below 3 ng/mL and plasma LH levels started rising until full recovery was reached at day 84 with levels of FE200486 hovering around 1 ng/mL. Additionally, FE200486 was less potent at releasing histamine from isolated rat mast cells than any of the GnRH antagonists presently described in preclinical reports.

Animals↗

PubMed2001

Seasonal changes of reproductive behavior and fecal steroid concentrations in Père David's deer.

From July 1997 to September 1997 and from March 1998 to July 1998, we studied reproductive behaviors of Père David's deer in Dafeng, China. During the field behavioral observations, we collected fresh voided fecal samples from the Père David's stags and hinds periodically and kept those samples under -20 degrees C until laboratory analysis. We analyzed the fecal testosterone, estradiol, and progesterone concentrations in those samples using radioimmunoassay. During this study, we also recorded 17 types of male reproductive behaviors and nine types of female reproductive behaviors. Reproductive behaviors and the fecal steroid concentrations showed overt seasonal fluctuations. There were statistically significant correlations between some male reproductive behaviors, such as anogenital sniffing, urine sniffing, urine spraying, wallowing, bellowing, antler adorning, Antler swags mud, chasing, herding hinds, chin resting, mounting and copulating, with the fecal testosterone concentrations. These results suggested that seasonal reproductive behaviors in stags are strongly associated with circulating testosterone. We also found that some female reproductive behaviors fluctuate corresponding with changes in fecal estrogen concentrations. Although there was no direct evidence to confirm the correlations between female reproductive behaviors and fecal estrogen in our experiment, we could not rule out that reproductive activities of hinds were largely related to ovarian estrogen secretion, and estrogen is necessary for inducing female reproductive behaviors.

Acclimatization↗

PubMed2001

Vertebral wedge angle measured by morphometric X-ray absorptiometry.

Vertebral wedge angle is greater in older men than in women of similar age, and increases with age in men. Wedge angle may depend less on bone size than other methods (for example, height ratios), and thus could be more effective at identifying wedge deformities. We aimed to compare mean wedge angle measured by morphometric X-ray absorptiometry (MXA) in young men and women, to assess the effect of age on wedge angle in women, and to compare wedge angle and anterior-posterior (ha/hp) height ratios for the identification of vertebral deformities. Mean wedge angle was similar in normal men (n = 46) and women (n = 106) ages 22-50 years, and did not change significantly with age in normal women ages 22-83 years (n = 222). MXA reference intervals for ha/hp ratios (trimmed mean minus 3.0 SD) and wedge angle (trimmed mean +/- 3.0, 2.5 and 2.0 SD) were used to identify vertebral wedge deformities in 83 women with osteoporosis, ages 49-87 years. For agreement with semiquantitative assessment of radiographs (SQ), kappa (kappa) = 0.76 for wedge angle mean plus 2.0 SD, and 0.74 for ha/hp height ratio mean minus 3.0 SD. Sensitivity was marginally better for wedge angle plus 2.0 SD than for ha/hp when all SQ grades of deformity were included, but there was no difference between methods for detection of moderate to severe deformities (grades 2 to 3). Diagnostic values for the two approaches were broadly similar. The results of this analysis do not provide strong evidence for the preferential use of the wedge angle approach.

Absorptiometry, Photon↗

PubMed2001

Short-term precision for morphometric X-ray absorptiometry.

Morphometric X-ray absorptiometry (MXA) is a low-radiation technique used for the identification of vertebral deformities. The reliability of MXA measurements is dependent on the precision of the technique, and this is influenced by system error, variability associated with morphometric analysis, and variability within study populations. Short-term precision in vivo affects the identification of prevalent deformities, and may vary according to the age and health status of the study population. The aims of this study were to measure short-term precision in vitro and in vivo for MXA, and to compare intraoperator variability for repeat marking of radiographs in morphometric radiography (MRX) and scan images in MXA. For short-term precision in vitro (based on 30 consecutive MXA phantom scans), the coefficient of variation (CV) was approximately 1%. Intraoperator variability for repeat marking of baseline radiographs and MXA scans (marked without the compare facility) in a population-based group of 32 postmenopausal women, was significantly lower for MRX (CV for vertebral heights = 1.5%) than for MXA (CV = 2.9%). The CV for duplicate same-day MXA scans performed in subjects with osteoporosis (n = 20) was 2.2% for vertebral heights between T8 and L4 using the compare facility, and 4.8% when scans were analyzed without the compare facility. We conclude that short-term precision for MXA is good for vertebrae T8 to L4, but the technique is limited due to poor image resolution in the upper thoracic vertebrae. Intraoperator variability for repeat marking was lower for MRX, but the error associated with marking MXA scans remained below the minimum change required for identification of a vertebral deformity.

Absorptiometry, Photon↗

PubMed2001

Longitudinal evaluation of morphometric X-ray absorptiometry for the identification of vertebral deformities.

Morphometric X-ray absorptiometry (MXA) has not been evaluated for the identification of incident vertebral deformities. The reliability of longitudinal measurements in quantitative vertebral morphometry is influenced by the precision of the technique. Long-term precision in vitro (weekly MXA phantom scans) assessed by retrospective cumulative sum (Cusum) analysis, detected one event during a 6-month period when the measurement process was 'out of control'. Inspection of service records revealed that repair work was performed around this timepoint. The coefficient of variation (CV) for long-term precision (vertebral heights) in a population-based sample of postmenopausal women ages 56 to 83, mean 65+/-6 years (n = 48), was 4.0% for morphometric radiography (MRX), 2.9% for MXA using the compare facility for analysis of serial scans, and 3.2% when 'compare' was not used. In women with osteoporosis ages 49 to 87, mean 67+/-9 years (n = 50). the CV was 5.0% for MRX, 4.1% for MXA using 'compare' and 8.5% without 'compare'. Precision errors for height ratios (MRX and MXA) were greater than for vertebral heights. Incident deformities were identified by MRX and MXA in the women with osteoporosis, using point prevalence, 20% minimum reduction in vertebral height, and percent least significant change (LSC) in vertebral heights and height ratios. Semiquantitative analysis of radiographs by a radiologist (Genant method) was used as the gold standard. The results were similar for MRX and MXA, and all morphometric criteria identified a similar proportion of true incident deformities, although the false positive rate was generally greater for the height ratio approaches. MXA has good long-term precision and is comparable to MRX for the identification of incident deformities when scans are analyzed with the compare facility.

Absorptiometry, Photon↗

PubMed2001

Chromosome landing at the bacterial blight resistance gene Xa4 locus using a deep coverage rice BAC library.

Xa4 is a dominantly inherited rice gene that confers resistance to Philippine race 1 of the bacterial blight pathogen Xanthomonas oryzae pv. oryzae in rice. In order to isolate the gene by positional cloning, a bacterial artificial chromosome (BAC) library was constructed from genomic DNA isolated from an Xa4-harboring accession, IRBB56. The library contains 55,296 clones with an average insert size of 132 kb, providing 14 rice genome equivalents. Three DNA markers closely linked to Xa4 were used to screen the library. The marker RS13, a resistance gene analogue that co-segregates with Xa4, identified 18 clones, of which four and six, respectively, were simultaneously detected by the other two markers, G181 and L1044. Fingerprinting and Southern analysis indicated that these clones overlapped and define an interval spanning 420 kb. In an F2 population derived from an indica variety, IR24, and its Xa4-containing near isogenic line (NIL), IRBB4, the susceptible plants were screened in order to map the Xa4 gene genetically and physically. Out of 24 insert ends isolated from the BACs in the contig, three revealed polymorphisms between IR24 and IRBB4. Two insert ends, 56M22F and 26D24R, flanked Xa4 on each side. Based on the overlap of the BACs, six overlapping clones were considered to include the Xa4 allele, one of which, 106P13, was chosen for further investigation.

Blotting, Southern↗

PubMed2001

Prokaryotically expressed Buthus martensii Karsch insect depressant toxin has insecticidal effects.

An insect depressant toxin Buthus martensii Karsch insect toxin 4 (BmK IT(4)) cDNA was cloned into the prokaryotic expression vector pSW202 and expressed in HB101 host cells. The authenticity of this in vitro expressed peptide was confirmed by Western blotting, mass spectrometry and N-terminal peptide sequencing. Bioassays using growth media supplemented with BmK IT(4) demonstrated that, at the end of the 5-day experimental period, about 77% of the testing cotton bollworm larvae were killed. Furthermore, the average weight picked up by larvae grown on BmK IT(4) containing media amounts only to 0.7% of that of control group. Our results indicate that BmK IT(4) may be used for biological control of insect damages in place of other traditional insecticides.

Amino Acid Sequence↗