First Identification of the MHC-DPA1 Alleles in Tibetan Macaques (Macaca thibetana).
Ten novel MHC-DPA1 alleles were identified in Tibetan macaques (Macaca thibetana).
Animals↗
Biomedical subjects
X S Zhang
Publications and source records attributed to X S Zhang.
Hormone-regulated inflorescence induction and TFL1 expression in Arabidopsis callus in vitro.
To study hormone-regulated inflorescence development, we established the in vitro regeneration system of Arabidopsis inflorescences in the presence of cytokinin and auxin. Media containing a combination of thidiazuron (TDZ) and 2,4-dichlorophenoxyacetic acid (2,4-D) were used to induce callus formation. Higher frequencies of calli were obtained by using the inflorescence stems as explants. After transferring the calli to media containing a combination of zeatin and indole-3-acetic acid (IAA), the inflorescences were induced from the calli. The morphology of regenerated inflorescences was similar to that of inflorescences in plants; however, flowers of regenerated inflorescences often lacked a few floral organs. Furthermore, TFL1, a gene involved in floral transition in Arabidopsis, was activated during the inflorescence induction. Our results suggest that the TFL1 gene plays an important role in hormone-regulated inflorescence formation.
2,4-Dichlorophenoxyacetic Acid↗
Primary leiomyosarcoma of the great saphenous vein: case report.
OBJECTIVE: To describe a case of primary leiomyosarcoma of the great saphenous vein. PATIENT RECORD: A 59-year-old Chinese lady presented with two painful lumps in the right thigh in the line of the great saphenous vein. At surgery, in September 2004, two tumors in the right great saphenous vein above the knee were excised with the intervening normal vein. Histopathological studies confirmed both masses as leiomyosarcoma. Radiotherapy was given postoperatively. The patient has been followed-up for 300 days after surgery with no evidence of local or distant metastasis. CONCLUSION: Leiomyosarcoma of the great saphenous vein can exist at more than one site. Tumor resection and radiotherapy was associated with good patient prognosis.
Female↗
Pistil induction by hormones from callus of Oryza sativa in vitro.
This study describes the successful formation of floral organ pistil from the callus of pistil explants of Oryza sativa L. For induction of floral organs, different explants--including young embryo, lemma, palea and pistil--were used for callus induction with different combinations of N(6)-benzyladenine and 2,4-dichlorophenoxyacetic acid (2,4-D). High frequencies of callus formation from pistil and young embryo explants were achieved. Floral organs were induced after calli from pistils were transferred to medium containing both zeatin and 2,4-D. The morphological characteristics of the pistil-like organs are very similar to those formed in planta though with minor differences. Further histological study revealed that the in vitro pistil contains an ovule within its ovary. Furthermore, a pistil-specific gene, OsMADS3 used as a molecular marker for pistil identity, was expressed in the pistil-like organs as it was in pistils in the flower of the plant.
2,4-Dichlorophenoxyacetic Acid↗
Molecular evolution of calmodulin-like domain protein kinases (CDPKs) in plants and protists.
Many genes for calmodulin-like domain protein kinases (CDPKs) have been identified in plants and Alveolate protists. To study the molecular evolution of the CDPK gene family, we performed a phylogenetic analysis of CDPK genomic sequences. Analysis of introns supports the phylogenetic analysis; CDPK genes with similar intron/exon structure are grouped together on the phylogenetic tree. Conserved introns support a monophyletic origin for plant CDPKs, CDPK-related kinases, and phosphoenolpyruvate carboxylase kinases. Plant CDPKs divide into two major branches. Plant CDPK genes on one branch share common intron positions with protist CDPK genes. The introns shared between protist and plant CDPKs presumably originated before the divergence of plants from Alveolates. Additionally, the calmodulin-like domains of protist CDPKs have intron positions in common with animal and fungal calmodulin genes. These results, together with the presence of a highly conserved phase zero intron located precisely at the beginning of the calmodulin-like domain, suggest that the ancestral CDPK gene could have originated from the fusion of protein kinase and calmodulin genes facilitated by recombination of ancient introns.
Amino Acid Sequence↗
Derived fuzzy knowledge model for estimating the depth of anesthesia.
Reliable and noninvasive monitoring of the depth of anesthesia (DOA) is highly desirable. Based on adaptive network-based fuzzy inference system (ANFIS) modeling, a derived fuzzy knowledge model is proposed for quantitatively estimating the DOA and validate it by 30 experiments using 15 dogs undergoing anesthesia with three different anesthetic regimens (propofol, isoflurane, and halothane). By eliciting fuzzy if-then rules, the model provides a way to address the DOA estimation problem by using electroencephalogram-derived parameters. The parameters include two new measures (complexity and regularity) extracted by nonlinear quantitative analyses, as well as spectral entropy. The model demonstrates good performance in discriminating awake and asleep states for three common anesthetic regimens (accuracy 90.3 % for propofol, 92.7 % for isoflurane, and 89.1% for halothane), real-time feasibility, and generalization ability (accuracy 85.9% across the three regimens). The proposed fuzzy knowledge model is a promising candidate as an effective tool for continuous assessment of the DOA.
Algorithms↗
EEG complexity as a measure of depth of anesthesia for patients.
A new approach for quantifying the relationship between brain activity patterns and depth of anesthesia (DOA) is presented by analyzing the spatio-temporal patterns in the electroencephalogram (EEG) using Lempel-Ziv complexity analysis. Twenty-seven patients undergoing vascular surgery were studied under general anesthesia with sevoflurane, isoflurane, propofol, or desflurane. The EEG was recorded continuously during the procedure and patients' anesthesia states were assessed according to the responsiveness component of the observer's assessment of alertness/sedation (OAA/S) score. An OAA/S score of zero or one was considered asleep and two or greater was considered awake. Complexity of the EEG was quantitatively estimated by the measure C(n), whose performance in discriminating awake and asleep states was analyzed by statistics for different anesthetic techniques and different patient populations. Compared with other measures, such as approximate entropy, spectral entropy, and median frequency, C(n) not only demonstrates better performance (93% accuracy) across all of the patients, but also is an easier algorithm to implement for real-time use. The study shows that C(n) is a very useful and promising EEG-derived parameter for characterizing the (DOA) under clinical situations.
Adult↗
Discrimination of anesthetic states using mid-latency auditory evoked potential and artificial neural networks.
This study was undertaken to determine whether artificial neural network (ANN) processing of mid-latency auditory evoked potentials (MLAEPs) can identify different anesthetic states during propofol anesthesia, and to determine those parameters that are most useful in the identification process. Twenty-one patients undergoing elective abdominal surgery were studied. To maintain general anesthesia, the patients received propofol (3-5 mgkg(-1) h(-1) intravenously). Epidural analgesia at the level of T4-5 blocked painful stimuli. MLAEP was recorded continuously with patients awake, during induction, during maintenance of general anesthesia, and during emergence until the patients were recovered from anesthesia. Latencies of the 5 MLAEP peaks and three peak to peak amplitudes were measured, along with hemodynamic parameters (heart rate, systolic, and diastolic arterial blood pressure). Four-layer ANNs were used to model the relationship between the parameters of the MLAEP and the four different states (awake, adequate anesthesia, during/before intraoperative movement, and emergence from anesthesia). The best identification accuracy was obtained using only the five latencies. The combination of five latencies and three amplitudes did not improve the identification accuracy. Use of the only the three hemodynamic parameters produced a much poorer identification. This study suggests that the MLAEP has useful information for identifying different anesthetic states, especially in its latencies. A nonlinear discrimination approach, such as the ANN, can effectively capture the relation between the MLAEP patterns and the different states of anesthesia.
Anesthesia↗
Multiple drug resistance phenotype of human endothelial cells induced by vascular endothelial growth factor 165.
AIM: To investigate the effect of vascular endothelial growth factor 165 (VEGF165) on sensitivity of endothelial cells to anticancer drugs. METHODS: Human dermal microvessel endothelial cells (HDMEC) were incubated with anticancer drugs in the presence of VEGF165. Survival of endothelial cells was assayed by MTT method. DNA fragments of apoptosis were detected by agarose electrophoresis. Potential mechanisms underlying the effect of VEGF165 on endothelial cells were investigated with RT-PCR and Western blot analysis. RESULTS: VEGF165 induced the multidrug resistance phenotype of HDMEC to a wide variety of anticancer drugs such as epirubicin, cisplatin, etoposide, mytomycin C, vincristine, CPT-11, and taxol in vitro. This protective effect was partly due to the up-regulation of lung drug resistance protein (LRP) and multidrug resistance-associated protein (MRP), as well as the down-regulation of Bax protein induced by VEGF165. CONCLUSION: VEGF165 induced multidrug resistance phenotype of endothelial cells, which implicated the anti-angiogenic effect of anticancer drugs might depend on microenvironment of tumors in vivo.
Angiogenesis Inhibitors↗
Immunoglobulin A secretion into saliva during dual sympathetic and parasympathetic nerve stimulation of rat submandibular glands.
Salivary secretion of proteins from rat submandibular glands was studied using graded stimulation of the parasympathetic nerve in isolation, and then at a fixed rate in combination with graded sympathetic nerve stimulation. Increasing the frequency of parasympathetic nerve stimulation per se caused a gradual increase in the secretion of peroxidase (from acini) but only small increases in proteinase (from ductal cells) and IgA outputs. Dual stimulations, with an increasing frequency of sympathetic nerve stimulation on a background of low frequency parasympathetic nerve stimulation, showed that maximal acinar secretion of peroxidase required only a low frequency of additional sympathetic stimulation, whereas ductal secretion of kallikrein was greatest with the highest frequency of additional sympathetic stimulation (20 Hz in bursts). IgA secretion also required high frequency additional sympathetic stimulation in bursts for greatest output. Although a synergism occurred with parasympathetic plus sympathetic nerve stimulation for the secretion of both peroxidase and kallikrein it was not evident for the secretion of IgA. This presumably reflects a difference for exocytosis of proteins stored in granules (e.g. peroxidase and kallikrein) compared to those proteins continuously transported across the plasma membrane in vesicles by transcytosis. This work confirms that vesicular movement of secretory IgA can be increased by both parasympathetic and sympathetic nerve stimulation, but the frequency parameters differ for each nerve.
Animals↗
Apoptosis induced by ceramide in hepatocellular carcinoma Bel7402 cells.
AIM: To study the biological function of ceramide signaling in Bel7402 cells. METHODS: Inhibition of cell growth was assayed using MTT method. Morphologic assessment of apoptosis was performed with fluorescence microscope. DNA fragmentation was detected by electrophoresis and flow cytometry. The levels of protein p53, Bcl-2, and Bax were measured with Western blot. RESULTS: Bel7402 cells treated with C2-ceramide underwent cell proliferation inhibition. IC50 value was 14.28 mumol.L-1. After treatment of Bel7402 with ceramide, the morphologic changes including reduction in volume, nuclear chromatin condensation, fluorescence strength were observed. SubG1 peaks were detected on flow cytometry (FCM). Agarose gel electrophoresis of DNA from cells treated with ceramide revealed "ladder" pattern. The Western blot assay from cell extracts showed that the levels of protein p53 were decreased after ceramide treatment. The levels of protein Bcl-2 were decreased also. But the levels of Bax protein showed no difference between untreated cells and treated cells. CONCLUSION: Ceramide induces apoptosis in Bel7402 cells, related to Bcl-2 down-regulation.
Apoptosis↗
In vivo biocompatibility and mechanical study of novel bone-bioactive materials for prosthetic implantation.
Two epoxy materials with or without adhesively bonded hydroxyapatite (HA) coatings were studied for their biocompatibility and mechanical pushout strength using in vivo implantation in the rabbit lower femur for a duration of 10 days to 6 months. Both were two-part epoxies cured at room temperature for 24 h, with material 1 (Ampreg 26; SP Systems Limited, Cowes, UK) postcured at 110 degrees C (Tg approximately 80 degrees C) and Material 2 (CG5052; Ciba Geigy Limited, Cambridge, UK) at 125 degrees C (Tg approximately 120 degrees C). Implantation in dead rabbit bone was performed to provide mechanical baseline levels. Polymethylmethacrylate (PMMA) and conventionally HA-coated titanium alloy (Ti-6Al-4V) were used as control materials. In the biological study, different fluorescent dyes were used to label newly formed bone. After 6 weeks of implantation, results from mechanical pushout tests showed that the interfacial shear strength (ISS) values were significantly higher than for dead bones with each of the different implants (p < .01-.001). HA-coated material 2 showed a significantly higher ISS value than the uncoated material (p < .05) after 6 weeks' implantation. However, the ISS value for the uncoated material 2 was significantly higher than for PMMA controls (p < .05). No significant differences in the ISS values were shown between HA-coated materials 1 and 2 and Ti-6Al-4V on in vivo implantation for 6 weeks. Failure points of the pushout test from the three HA-coated materials were defined by scanning electron microscopy. Specimens implanted with both HA-coated epoxies were fractured within the HA-coatings or the bone, while with HA-coated Ti-6Al-4V cracked between the coating and metal implant. The percentage of bone in contact with the implant surface was obtained by image analysis which showed that there were no significant differences between different materials after short time implantation (up to 6 week). Long-term implantation of the HA-coated material 2 showed that the percentage of bone contact had increased from 52.8+/-1.1% (6 week) to 80.0+/-0.3% (3 months) (p < .01) and remained at 81.0+/-0.8% (6 months). Measurements of bone mineralization rate (BMR) showed that after 3 weeks of implantation, there were no significant differences between PMMA and uncoated materials 1 and 2. After 6 weeks, the BMRs in animals implanted with either HA-coated material 1 or 2 were significantly higher than with HA-coated Ti-6Al-4V (p < .05-.0001 in both cases), but with HA-coated material 2 was lower than with this material uncoated (p < .05-.001). No significant differences were found between the two HA-coated epoxy materials. In addition, there were always lower BMRs during the third week of implantation than other periods regardless of biomaterial implanted. The study indicated that the adhesively bonded HA-coated novel epoxy materials were superior to conventional plasma-sprayed Ti-6Al-4V implants with respect to both BMR and bone integration with the implant surfaces. Adhesively bonded HA-coated epoxy materials had similar ISS values to HA-coated Ti-6Al-4V, but the former failed within the bone and coating, while the latter showed splitting between coating and metal.
Algorithms↗
Predicting movement during anaesthesia by complexity analysis of electroencephalograms.
A new approach to predicting movement during anaesthesia by using complexity analysis of electroencephalograms (EEG) signals is presented. The raw EEG signal is first decomposed into six consecutive different scaling components by wavelet transform on the basis of its self-similarity. The Lempel-Ziv complexity measures C(n) are extracted from the raw EEG and its corresponding components by complexity analysis. Prediction of movement during anaesthesia is then made by a four-layer artificial neural network (ANN) using the C(n)s. The combination of these three different approaches enables the system to address the non-analytical, non-stationary, non-linear and dynamical properties of the EEG. From 20 dog experiments, 109 distinct EEG recordings are collected under isoflurane anaesthesia. Testing the ANN using the 'drop one dog' method, the performance obtained for the system in detecting movement is: sensitivity 88%, specificity 97% and accuracy 92%. Comparisons with other methods, such as spectral edge frequency, median frequency and principal component analysis, show that the proposed system has a certain advantage. This new method is computationally fast and well suited for realtime clinical implementation.
Anesthesia↗
In situ localization of apoptotic changes in the interface membrane of aseptically loosened orthopaedic implants.
Twenty specimens of bone-implant interface membrane from THR/TKR were used for in situ localization of apoptotic changes. A panel of antibodies was used to label leukocyte antigens (CD68 and CD3) cytokines (IL-1alpha and IL-1beta) and apoptosis inhibiting and promoting proteins (bcl-2 and bax) by means of immunohistochemical techniques. A DNA fragment test on the tissue sections was also carried out to confirm actual cell death using the enzyme terminal deoxy nucleotidyl transferase (TdT) to incorporate biotinylated nucleotide with the 3'-OH DNA ends. Leukocyte antigen staining showed that there were large numbers of CD68 positive macrophages as well as multinucleate giant cells (MNGC) but that CD3 positive lymphocytes were also present in the interface membrane. The leukocyte surface antigen staining pattern corresponded to previous findings [1]. Immunostaining with bcl-2 and bax antibodies revealed that both of these proteins were expressed in the cytoplasm of the cells in the interface membrane but they showed different cellular patterns. Bcl-2 was localized in a small number of lymphocyte-like cells while bax was expressed by large numbers of cells, mainly macrophages. The number of cells which expressed bcl-2 was significantly lower than that of bax (P<0.01). DNA fragment localization occurred mostly in a layer of cells (1- 3 cells deep) next to the implant surface. Again the level of DNA fragment-containing cells was significantly lower than that of bax positive cells (P<0.01). The results, for the first time, indicate that there is an apoptotic activity occurring in cells in the interface membrane, but not all the cells which express apoptosis-promoting protein (i.e. bax) will enter into the phase of cell death.
Journal Article↗
Modeling the relationship between concurrent epicardial action potentials and bipolar electrograms.
A signal analysis approach to building the relationship between concurrent epicardial cell action potentials (AP's) and bipolar electrograms is presented. Wavelet network, one nonlinear black-box modeling method, is used to identify the relationship between cell AP's and bipolar electrocardiograms. The electrical signals were simultaneously measured from the epicardium of isolated Langendorff-perfused rabbit hearts during three different rhythm conditions: normal sinus rhythm (NSR), normal sinus rhythm after ischemia (NSRI), and ventricular fibrillation (VF). For NSR and NSRI, the proposed modeling method successfully captures the nonlinear input-output relationship and provides an accurate output, but the method fails in case of VF. This result suggests that a time-invariant nonlinear modeling method such as wavelet network is not appropriate for VF rhythm, which is thought to be time-varying as well as chaotic, but still useful in detection of VF. A new arrhythmia detection algorithm, with potential application in implantable devices, is proposed for identifying the time of rhythmic bifurcation.
Action Potentials↗
Detecting ventricular tachycardia and fibrillation by complexity measure.
Sinus rhythm (SR), ventricular tachycardia (VT) and ventricular fibrillation (VF) belong to different nonlinear physiological processes with different complexity. In this study, we present a novel, and computationally fast method to detect VT and VF, which utilizes a complexity measure suggested by Lempel and Ziv [1]. For a specific window length (i.e., the length of data segment to be analyzed), the method first generates a 0-1 string by comparing the raw electrocardiogram (ECG) data to a selected suitable threshold. The complexity measure can be obtained from the 0-1 string only using two simple operations, comparison and accumulation. When the window length is 7 s, the detection accuracy for each of SR, VT, and VF is 100% for a test set of 204 body surface records (34 SR, 85 monomorphic VT, and 85 VF). Compared with other conventional time- and frequency-domain methods, such as rate and irregularity, VF-filter leakage, and sequential hypothesis testing, the new algorithm is simple, computationally efficient, and well suited for real-time implementation in automatic external defibrillators (AED's).
Algorithms↗
Constitutive secretion of kallikreins in vivo from rat submandibular glands.
In parasympathetic saliva from rat submandibular glands the relative proportions of the various tissue kallikreins differ from those in sympathetic saliva. Kallikreins in sympathetic saliva arise from exocytosis of prepackaged granules in granular tubules, so the kallikreins in parasympathetic saliva must come from a non-granular pool, and are likely to be secreted through a constitutive vesicular route. During periods devoid of stimulation in anaesthetised rats, the kallikreins have been found to accumulate progressively in glandular lumina in parasympathetic-like proportions. As this transport of kallikrein into lumina occurs continuously in vivo, independently of any stimulation or any secretion of fluid, it must arise by constitutive vesicular secretion. During parasympathetic stimulation, the kallikreins are secreted into the saliva at a greater rate than in the resting state but their proportions remain the same and the means by which this increase occurs is open to debate. Constitutively secreted true tissue kallikrein (rK1) has been found to have a different molecular form from that in secretory granules. The submandibular glands also contribute to the kallikreins normally circulating in the blood. Serum levels of kallikrein increased equally during either parasympathetic or sympathetic stimulation and were independent of the amounts secreted into the saliva, so are likely to have arisen from constitutive secretion via the basal sides of the cells, morphological evidence for which has been found in the mouse (Penschow & Coghlan, 1993).
Animals↗
Inactivation and conformational changes of yeast alcohol dehydrogenase in trifluoroethanol solutions.
Conformational changes of yeast alcohol dehydrogenase in trifluoroethanol solutions have been followed by fluorescence emission and circular dichroism spectroscopy. At low concentration (less than 5%), trifluoroethanol shows a reversible inhibition competitive to ethanol and noncompetitive to NAD+. The inhibition constants for native and structural-zinc-removed yeast alcohol dehydrogenase were 5.8 and 1.1 mM, respectively, suggesting that the active site becomes more flexible after the structural zinc is removed. At higher trifluoroethanol concentrations the enzyme was irreversibly inactivated. Comparison of inactivation and conformational changes of yeast alcohol dehydrogenase denatured in trifluoroethanol solutions shows that the extent of inactivation is larger than the extent of conformational changes at the same trifluoroethanol concentration. The results obtained from circular dichroism spectra show that the presence of trifluoroethanol can induce the formation of secondary structure of the enzyme.
Alcohol Dehydrogenase↗