High-spin states and K-forbidden decay in 172Hf.
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Journal Article↗
Biomedical subjects
C Yu
Publications and source records attributed to C Yu.
Conformational studies of a synthetic cyclic decapeptide fragment of rat transforming growth factor-alpha.
The solution conformation of a synthetic cyclic decapeptide [with sequence mimicking the third disulfide loop of rat transforming growth factor-alpha (rTGF-alpha)] in deuterated dimethyl sulfoxide was studied by 2D NMR. The determination of solution structures was based on NOE interproton distances, using a combination of distance geometry and simulated annealing protocols. The convergence of the selected structures was evident from the small atomic pairwise root-mean-square deviation values among them. Good agreement was noted between the experimental and simulated NOESY spectra, thereby reflecting the accuracy of the calculated solution structures. Analysis of the structures indicates that the residues Tyr5 and Arg9 exhibit similar side chain orientation as that in the corresponding disulfide loop of human transforming growth factor-alpha.
Amino Acid Sequence↗
Interactions of apolipoprotein E genotype, total cholesterol level, age, and sex in prediction of Alzheimer's disease: a case-control study.
OBJECTIVE: The joint effects of total cholesterol (TC) levels and the APOE genotype in Alzheimer's disease (AD) were evaluated because of previous reports that the APOE locus epsilon 4 allele was associated with both late-onset AD and elevated TC. DESIGN: Logistic regression was used to determine the effects of the APOE genotype, TC, age, and sex on prediction of AD in a community-based study of 206 cases and 276 controls. RESULTS: The relationship of the APOE genotype and AD was dependent on TC, age, and sex. However, current TC level does not fully explain the epsilon 4-Alzheimer's disease association. Affected men with higher TC and age under 80 years had the highest epsilon 4 allele frequencies. The epsilon 4 frequency declined significantly with age. SIGNIFICANCE: A pathologic role of higher TC or cholesterol-based differential survival of epsilon 4-carrying individuals may be involved in the relationship of the epsilon 4 allele with AD. The observed association of the APOE genotype and AD is expected to depend on the age, sex, and TC distributions of a given sample.
Aged↗
A unique swivel-tether system for continuous i.v. infusions in freely mobile unrestrained rabbits.
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Journal Article↗
Dr. Gao Zhuofeng's experiences in the treatment of arrhythmia.
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Arrhythmias, Cardiac↗
[Exploration on experimental conditions of dot-ELISA for Trichomonas vaginalis using intact parasite antigen-monoclonal antibody detecting system].
This paper deals with the effect of different experimental conditions including the number of parasite, blocking fluid, incubation time and different types of antigens on dot-ELISA for Trichomonas vaginalis. Five microlitres of freshly washed intact worms at a concentration of 7.7 x 10(5)-3 x 10(8) cells/ml were added onto nitrocellulose membrane blocked with 1% BSA, 10% bovine serum or milk power (0.1%, 0.25%, 0.5%, 5%). Dot-ELISA using nitrocellulose membrane containing whole cell antigen 2.5 x 10(7) cells/ml, blocked by 0.5% defatted milk power at 37 degrees C for one hour before the incubation in McAb, incubated at 37 degrees C for one hour in McAb and SPA respectively was found to give more promising results. The whole cell antigen could be preserved for four months at 4 degrees C and -20 degrees C.
Animals↗
[Determination of the progesterone antagonist lilopristone in serum by RP-HPLC].
To 1.0 ml of serum containing lilopristone were added RU486 solution (internal standard, IS) and 1 ml of 1.0 mol.L-1 NaOH. The mixture was extracted with diethyl ether for 2 times. After extraction, the combined organic phase was evaporated to dryness and the residue was dissolved in the mobile phase and washed with petroleum ether. After centrifugation, 20 microliters of the lower layer was subjected to HPLC. A muBondapak-C18 (10 microns) column (30 cm x 3.9 mm) was used and the column temperature was kept at 50 degrees C. The flow rate of mobile phase (methanol-dichloromethane--0.01 mol.L-1 phosphate buffer, pH 4.0, 67:5:28 v/v) was 1.1 ml.min-1 and UV detection was performed at 302 nm. The retention times of lilopristone and IS were 6.85 and 9.07 min respectively and the detection limit was 10 ng.ml-1 (S/N > or = 4) serum. The extraction recoveries of lilopristone and IS were over 85%. The relative standard deviations were 2.21 to 4.23%. This method has been applied to study the pharmacokinetic of lilopristone in rats.
Animals↗
[Effects of different fixatives for Trichomonas vaginalis in indirect fluorescent antibody test].
This paper dealt with the effects of different fixatives for Trichomonas vaginalis in indirect fluorescent antibody test. T. vaginalis fixed by formalin, methanol or alcohol displayed clear flagella. The parasites fixed by methanol and alcohol showed specific ring-like fluorescence with 1-2 bright dots. Antigen slides prepared from different Trichomonas strains, different number of parasites and anti-Trichomonas vaginalis McAb strains in IFA presented different results. Antigen slides showed the best results when using parasites at concentrations of 1.2 x 10(6) cells/ml or 2.4 x 10(5) cells/ml. Antigen preparations stored at 4 degrees C or -20 degrees C remained reactive throughout the experimental period of three months.
Animals↗
Oxymetry deep in tissues with low-frequency electron paramagnetic resonance.
We have measured the oxygen concentration in the body water of murine FSa and NFSa fibrosarcomas using a new method for quantitative oxygen concentration determination deep in the tissues of a living animal. The measurement uses unusually low-frequency electron paramagnetic spectroscopy sensitive to substrate 7 cm deep in tissue, partially deuterated spin probes (spin labels of molecular mass 195, approximating that of glucose) whose distribution compartment can be targeted with facile adduct substitution, and novel analytic techniques. We show that the water-compartment oxygen concentration of the tumors decreases as the tumor size increases and also shows a trend to decrease as radiobiologic hypoxia increases. An oxymetric spectral image of the tumor is presented. The technique will improve with larger human tissue samples. It provides the potential to quantitatively assess tissue hypoxia in ischemic or preischemic states in stroke and myocardial infarction. It will allow direct assessment of tumor hypoxia to determine the usefulness of radiation and chemotherapy adjuvants directed to hypoxic cell compartments.
Animals↗
Surface states in doped polymers.
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Journal Article↗
Hormone binding domain of human glucocorticoid receptor. Enhancement of transactivation function by substitution mutants M565R and A573Q.
To determine the importance of specific amino acids in the hormone-binding domain of the human glucocorticoid receptor (hGR), we have generated mutants M565R, G567A, and A573Q. In hormone binding assays using [3H]cortisol, half-maximal saturation of dexamethasone competition was achieved at 10 pM with hGR M565R and hGRA573Q compared to 10 nM with wild type hGR. Similar results were obtained in competition assays with [3H]dexamethasone and the glucocorticoid antagonist RU 486. The substitution mutants M565R and A573Q demonstrated a higher relative affinity for aldosterone compared to the wild type hGR. In CV-1 cells cotransfected with the mutant receptors, hGR M565R and A573Q showed a remarkable 6-fold elevated transcription activation of the chimeric reporter gene mouse mammary tumor virus-chloramphenicol acetyl-transferase (MMTV-CAT). The mutant hGR G567A failed to bind agonists and antagonists efficiently. Immunoblotting with hGR specific antibodies of the whole cell extract from transfected CV-1 cells revealed that these differences in hormone binding and transcription activation were not due to the decreased levels of expression. These data support that idea that Gly567 in the hGR hormone-binding domain lies in a region crucial to ligand binding and transactivation function.
Amino Acid Sequence↗
Substitution of Cys-560 by Phe, Trp, Tyr, and Ser in the first zinc finger of human androgen receptor affects hormonal sensitivity and transcriptional activation.
We have established and characterized four human androgen receptor (AR) mutants, AR C560F, C560W, C560Y, C560S). To assess the functional significance of these substitutions, we compared the transcriptional activation, hormone binding affinity, receptor-DNA interaction, and the subcellular distribution of the hormone-receptor complexes. Binding studies showed that all mutants bound methyltrienolone (R1881) with wild type affinity (Kd = 0.5 nM). Transactivation efficiency, as compared to wild type AR, increased 150% with C560F and decreased to 70% with C560W and C560Y and to 40% with mutant C560S. Subcellular receptor distribution showed that 85% of C560F bound with hormone was extracted from the nuclear fraction and 15% in the cytosol. Gel mobility shift assays showed that C560F expressed in CV-1 cells bound to an androgen responsive element (ARE) with equal efficiency as the wild type human AR. The mutants C560W and C560Y demonstrated a lower ability to bind to ARE, whereas C560S showed a significantly lower ability to interact with ARE. We propose that the change in polarity introduced into the loop structure by C560S leads to a shorter period of contact between the mutant receptor and DNA resulting in decreased transcriptional activation levels.
Amino Acids↗
DLA-identical bone marrow grafts after low-dose total body irradiation: the effect of canine recombinant hematopoietic growth factors.
Previous studies found that bone marrow (BM) allografts from DLA-identical littermates resulted in survival of two thirds of recipient dogs after otherwise lethal doses of 450 to 600 cGy of total body irradiation (TBI) because of successful allografts or autologous recovery after rejection of the allografts. The current study asked whether survival could be further improved by treating allograft recipients with recombinant canine granulocyte colony-stimulating factor (G-CSF), stem cell factor (SCF), or G-CSF/SCF. Of 21 dogs, 14 (67%) receiving allografts but no growth factors survived, 10 with successful allografts (including 5 mixed chimeras) and 4 with autologous recovery; whereas 7 animals died, 5 from infections during BM aplasia and 2 from acute graft-versus-host disease. By comparison, 30 of 34 dogs (88%) receiving hematopoietic growth factors in addition to the BM graft survived, 17 with successful allografts (including 10 mixed chimeras) and 13 with autologous recovery; whereas 4 died, all with infection related to BM aplasia after rejection of the allograft. Survival was similar for recipients of G-CSF, SCF, or the combination of G-CSF and SCF. Logistic regression analyses, which accounted for possible effects of TBI dose, showed a trend for improved survival in dogs receiving growth factors (P = .09), no change in allogeneic engraftment (P = .74), and a slight increase in autologous recovery (P = .22). In agreement with previous data, we found that grafts of BM from DLA-identical littermates improved survival of recipient dogs exposed to low but otherwise lethal doses of TBI. A further improvement in survival could be achieved by additional treatment with G-CSF, SCF, or G-CSF/SCF. Results suggest that treatment by hematopoietic growth factors along with BM grafts should be considered for victims of radiation accidents.
Animals↗
Three-dimensional structure in solution of griseoviridin, a group A antibiotic.
The solution conformation of griseoviridin, a broad spectrum antibiotic, has been determined by 1H-NMR in deuterated dimethylsulfoxide. The structural determination is based on experimental data of NOE constraints Five structures were obtained from restrained molecular dynamics calculations, by imposing (the condition for) a minimum violation of distance constraints. These structures satisfy well the experimental restraints, with small values of NOE violation and total energies. On comparison with its crystal structure, a good agreement is noted with a backbone root-mean-square deviation value of 0.084 nm. However, a small variation between the structures is observed at the aminodecanoic acid part of the molecule.
Anti-Bacterial Agents↗
Synthesis and pharmacological evaluation of isoindolo[1,2-b]quinazolinone and isoindolo[2,1-a]benzimidazole derivatives related to the antitumor agent batracylin.
The synthesis and pharmacological activity of isoindolo[1,2-b]quinazolin-12(10H)-ones and isoindolo[2,1-a]benzimidazoles related to batracylin are described. The acute toxicity of batracyclin has been associated with the formation of its N-acetyl metabolite which is a potent inducer of unscheduled DNA synthesis in rat hepatocytes. The desamino derivative and the 8-aza analog of batracylin retained the ability to inhibit topoisomerase II but did not induce unscheduled DNA synthesis. While less active than batracylin, these analogs were cytotoxic to CCRF CEM leukemia cells. The isoindolo[2,1-a]benzimidazole derivatives were inactive as topoisomerase II inhibitors and, in general, failed to exhibit comparable antitumor activity or to induce unscheduled DNA synthesis.
Animals↗
Use of (CA)n polymorphisms to determine the origin of blood cells after allogeneic canine marrow grafting.
We have used a polymerase chain reaction-based assay measuring polymorphic (CA)n repeats, a class of simple sequence repeats, to assess the success of allogeneic canine marrow transplants. Results were compared with those obtained with karyotype analysis of dividing cells in recipients that were sex mismatched with their marrow donors. Twenty recipients were conditioned for transplantation of genotypically DLA-identical littermate marrow by 450 cGy of total-body irradiation. In 2 recipients, results could not be compared, since either only cytogenetic or dinucleotide (CA)n marker data existed. Both dogs had autologous marrow recovery. In 15 of the remaining 18 recipients, complete agreement was found between the results obtained with dinucleotide (CA)n markers, cytogenetic studies, and granulocyte changes after transplantation. Seven of the 15 showed eventual autologous recovery, 6 displayed mixtures of host and donor cells, and 2 showed donor-type hematopoiesis. Two of the 18 dogs showed mixed chimerism with (CA)n markers and autologous recovery by cytogenetics, findings that may be related to differences in cells analyzed by the two techniques--i.e., all nucleated cells by (CA)n markers versus dividing cells by cytogenetics. In one additional recipient, results of marrow cytogenetics, granulocyte changes, and (CA)n markers were consistent with a successful allograft, while peripheral blood cytogenetics suggested autologous recovery, possibly the result of erroneous blood sampling. Polymerase chain reaction-based testing for dinucleotide repeat (CA)n polymorphisms, originally developed for genetic mapping in the dog, is useful and reliable when compared with cytogenetic studies, in assessing the success of allogeneic marrow transplants in dogs.
Animals↗
Cardiotoxin II from Taiwan cobra venom, Naja naja atra. Structure in solution and comparison among homologous cardiotoxins.
The three-dimensional structure in solution of cardiotoxin II, a membrane toxin from the venom of Taiwan cobra, Naja naja atra, was determined using 1H nuclear magnetic resonance spectroscopy and molecular modeling based on the hybrid distance geometry/dynamic simulated annealing technique. A complete sequence-specific proton assignment was obtained, and the secondary structures of the protein were determined from information on nuclear Overhauser effect connectivities, coupling constants, and hydrogen exchange were confirmed using the main-chain-directed strategy. Twelve simulated annealing structures found to be within a single family were selected based on the condition of distance constraint violation less than 0.02 nm and the dihedral angle violation less than 4 degrees. The average atomic root mean square deviation between the selected structures and their geometric average are 0.079 nm for the backbone atoms and 0.137 nm for all heavy atoms; they are 0.044 nm and 0.117 nm, respectively, when considering the secondary structural residues only. The molecule adopts a compact structure consisting of three major loops emerging from a globular head. These loops contain five strands to form double- and a triple-stranded antiparallel beta sheets. Comparisons are made between this structure and those of its homologous cardiotoxins in order to derive further information on their structural variations.
Amino Acid Sequence↗
Microvessel count and cerebrospinal fluid basic fibroblast growth factor in children with brain tumours.
Tumour growth is angiogenesis-dependent; brain tumours have more intense neovascularisation than other tumours and produce basic fibroblast growth factor, a potent angiogenic mediator. Because little is known about the release of basic fibroblast growth factor from brain tumours into extracellular fluids, we tested cerebrospinal fluid (CSF) from 26 children and young adults with brain tumours and 18 controls for basic fibroblast growth factor and for proliferative activity on cultured capillary endothelial cells. We also measured the density of microvessels in tumours by immunohistochemical staining. Basic fibroblast growth factor was detected in the CSF of 62% (16 of 26) patients with brain tumours but in none of the controls. Specimens with basic fibroblast growth factor stimulated DNA synthesis of capillary endothelial cells in vitro. Endothelial proliferative activity was blocked by neutralising antibodies to basic fibroblast growth factor. Basic fibroblast growth factor correlated with mitogenic activity in CSF in vitro (p < or = 0.0001), and with density of microvessels in histological sections (p < or = 0.005). A microvessel count of > or = 68 per 200 x field was associated with tumour recurrence (p = 0.005) and with mortality (p = 0.02). Basic fibroblast growth factor in brain tumours may mediate angiogenesis as measured by microvessel density in histological sections, so has potential as both a marker for neoplasia and a target for tumour treatments. Furthermore, evaluation of cerebrospinal fluid basic fibroblast growth factor, along with microvessel quantitation in biopsied tumours, may provide improved prognostic information for the management of patients with brain tumours.
Adolescent↗