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Biomedical subjects

Xue-Qing Chen

Publications and source records attributed to Xue-Qing Chen.

14 recordsLinked to original sources

Discovery pharmaceutics--challenges and opportunities.

Most pharmaceutical companies are now evaluating compounds for druglike properties early in the discovery process. The data generated at these early stages allow upfront identification of potential development challenges and thus selection of the best candidates for lead nomination. Most often, lead nomination candidates are selected based on pharmacological and toxicological data. However, many drugs in development suffer from poor biopharmaceutical properties due to suboptimal physiochemical parameters. The poor biopharmaceutical properties often lead to extended timelines and a higher cost of developing the compounds. To avoid these problems and choose the best compounds from a biopharmaceutical perspective, physicochemical parameters such as solubility, lipophilicity, and stability need to be evaluated as early as possible. Furthermore, the preformulation approaches used to evaluate the compounds for their pharmacokinetic and toxicological properties need to be optimized. This minireview summarizes some of the parameters and approaches that can be used to evaluate compounds in the early stages of drug discovery.

Biopharmaceutics↗

Expression of early growth response factor-1 in rats with cerulein-induced acute pancreatitis and its significance.

AIM: To observe the expressions of early growth response factor-1 (Egr-1) and tissue factor (TF) in rats with cerulein-induced acute pancreatitis and to explore its significance. METHODS: A large dose of cerulein was used to create the experimental acute pancreatitis model in rats. The changes of Egr-1 mRNA and protein in rats were observed during 30 min to 4 h after the treatment and immunohistochemical method was used to observe the localized expression of Egr-1 in tissues. In addition to the mRNA expression of Egr-1 target gene, TF was also observed. A blank control group, and a bombesin-administered group were used for comparison. RESULTS: After the stimulation of a large dose of cerulein, the rats showed typical inflammatory changes of acute pancreatitis. Thirty minutes after the stimulation, the mRNA expression of Egr-1 in the pancreatic tissue reached its peak and then declined, while the expression of Egr-1 protein reached its peak 2 h after the stimulation. Histologically, 2 h after the stimulation, almost all pancreatic acinar cells had the expression of Egr-1 protein, which was focused in the nuclei. The mRNA expression of TF occurred 1 h after the stimulation and gradually increased within 4 h. However, a large dose of bombesin only stimulated the pancreatic tissue to produce a little mRNA expression of Egr-1 and no mRNA expression of Egr-1 protein and TF. CONCLUSION: Egr-1 as a pro-inflammatory transcription factor may play an important role in the pathogenesis of acute pancreatitis by modulating the expression of TF.

Acute Disease↗

Aqueous and cosolvent solubility data for drug-like organic compounds.

Recently 2 QSPR-based in silico models were developed in our laboratories to predict the aqueous and non-aqueous solubility of drug-like organic compounds. For the intrinsic aqueous solubility model, a set of 321 structurally diverse drugs was collected from literature for the analysis. For the PEG 400 cosolvent model, experimental data for 122 drugs were obtained by a uniform experimental procedure at 4 volume fractions of PEG 400 in water, 0%, 25%, 50%, and 75%. The drugs used in both models represent a wide range of compounds, with log P values from -5 to 7.5, and molecular weights from 100 to >600 g/mol. Because of the standardized procedure used to collect the cosolvent data and the careful assessment of quality used in obtaining literature data, both data sets have potential value for the scientific community for use in building various models that require experimental solubility data.

Chromatography, High Pressure Liquid↗

[Analysis of factors effecting satisfaction of cochlear implants in prelingually deafened adolescents].

OBJECTIVE: By means of investigating how the benefit and the influence factors are for the pre-lingual deaf adolescents who received cochlear implantation (CI) METHODS: A questionnaire survey was conducted among 30 prelingually deaf adolescents-cochlear implant recipients, aged 9 approximately 20, 15 of which began to use hearing aid before the age of 6, and 19 of which had received speech testing after the CI, and their families to understand the degree of satisfaction, anticipation of the outcome. Nine of the 15 patients who began to use hearing aid before the age of 6 communicated by the oral communication/labial reading model (oral group), and 10 of the other 15 patients who had not used hearing aid after the age of 6 mainly communicated by sign language (sign group). RESULTS: The satisfaction score of the group with a hearing aid fitting history was 3.93 +/- 0.88, significantly higher than that of the group without a hearing aid fitting history (3.00 +/- 1.13, P < 0.05). The scores of speech production ability in vowel, consonant, single syllable, disyllable, trisyllable, and short sentence in the groups with and without a hearing aid fitting history were 76%/52%, 64%/45%, 71%/26%, 82%/96%, 68%/12%, and 49%/13% respectively (all P < 0.05), and there was no significant difference in the speech production ability in tone (P > 0.05) between these 2 groups. There were no significant differences in the total satisfaction degree, satisfaction degree in speech sound, and satisfaction degree in environmental sound between the oral group and sign group (all P > 0.05). The scores in vowel, consonant, single syllable, disyllable, trisyllable, short sentence, and tone of the oral and sign group were 74%, 60%, 64%, 61%, 57%, 43%, 27% and 43%, 39%, 26%, 26%, 20%, 6%, 5% respectively (all P > 0.01). The anticipation of the patient and the parents about outcome before implantation was negatively correlated with the satisfaction degree after implantation, (gamma = -0.479, P < 0.05). CONCLUSION: Cochlear implantation benefits greatly the deaf adolescent; however, it is necessary to establish a specific evaluation system according to recipients' needs.

Adolescent↗

Comparisons between neural response imaging thresholds, electrically evoked auditory reflex thresholds and most comfortable loudness levels in CII bionic ear users with HiResolution sound processing strategies.

CONCLUSIONS: The data collected in this study indicated that first Neural Response Imaging (NRI) thresholds had a better correlation with HiResolution most comfortable loudness (M) levels than tNRI thresholds. Electrically evoked auditory reflex thresholds (EARTs) had a higher correlation with HiResolution M levels than tNRI thresholds and a lower correlation than first NRI thresholds. NRI is a very useful method for programming the cochlear implants of young children who cannot demonstrate a reliable judgment of loudness. OBJECTIVE: To investigate how HiResolution sound processing, designed to deliver high-rate stimuli, relates to EARTs and electrically evoked compound action potential measurements produced by low-rate stimuli. MATERIAL AND METHODS: Nine profoundly hearing-impaired children and adults aged 6-29 years participated in the study. NRI responses were elicited using pulse trains consisting of biphasic pulses at a pulse width per phase of 32 micros delivered at a frequency of 30 Hz using SoundWave programming software. Stimuli were delivered to the odd electrodes (1, 3, 5, 7, 9, 11, 13 and 15) along the array. tNRI (NRI threshold) and first NRI thresholds were recorded for each stimulating electrode. "Speech bursts" stimuli used in EARTs recording were delivered to four electrodes at a time and stapedial reflexes were recorded from the impedance bridge. The M levels used were those used by each patient in their everyday HiResolution programs. RESULTS: For 8 patients (53 stimulating electrodes) the correlation between tNRI threshold and M level was r=0.675 (p=0.000) and that between first NRI thresholds and M level was r=0.741 (p=0.000). On average the M-level value was 20 CU (Current Unit) lower than the first NRI threshold value and 12 CU higher than the tNRI threshold value. The M-level patterns across the electrode array overall were similar to the tNRI or first NRI threshold patterns. For 7 patients (112 stimulating electrodes) the correlation between EART and M levels was r=0.710 (p=0.000). On average the EART value was 14 CU higher than the M-level value.

Adolescent↗

[Assembly of apoptin gene using oligodeoxyribonucleotides in vitro].

OBJECTIVE: To explore the method for in vitro gene assembly of apoptin-encoding DNA sequence, for instance, using a large number of oligodeoxyribonucleotides (oligos). METHODS: Based on the encoding sequence of apoptin gene (GeneBank accession number AY171617), a number of oligos were designed to assembly apoptin gene in pfu mix reaction system, and each oligo was 40 nucleotides (nt) in length, in which synonymous codon substitution was used to eliminate the restriction enzyme sites of Bgl II ( position 172, agatct-agatcc) and Hind III (position 306, aagctt-aatcct). The assembly mixture was further diluted and amplified with two end oligos. The targeting sequence was gel-purified, amplified for one more time, followed by the addition of T to the 3' end in the presence of Taq polymerase and dATP before cloning into pGEM-T easy vector. The positive clones were confirmed by restriction enzyme digestion and sequence analysis. RESULTS: The synthetic mixture presented obvious "tails" in the first PCR for assembly. After dilution of the mixture and amplification with two end oligos, clear DNA ladder bands with a clear targeted band were yielded. After PCR, the targeted gene was cloned into pGEM-T easy vector, and the positive clones were confirmed by sequence analysis with be identical to the designed coding sequence of apoptin gene. CONCLUSION: Gene assembly is a rapid and cost-effective approach for synthesis of genes or vectors, which allows simultaneous mutagenesis of several genes in vitro.

Base Sequence↗

Effects of probiotic on intestinal mucosa of patients with ulcerative colitis.

AIM: To investigate the effects of probiotic on intestinal mucosae of patients with ulcerative colitis (UC), and to evaluate the role of probiotic in preventing the relapse of UC. METHODS: Thirty patients received treatment with sulphasalazine (SASP) and glucocorticoid and then were randomly administered bifid triple viable capsule (BIFICO) (1.26 g/d), or an identical placebo (starch) for 8 wk. Fecal samples were collected for stool culture 2 wk before and after the randomized treatments. The patients were evaluated clinically, endoscopically and histologically after 2 mo of treatment or in case of relapse of UC. p65 and IkappaB expressions were determined by Western blot analysis. DNA-binding activity of NF-kappaB in colonic nuclear extracts was detected by electrophoretic mobility shift assay (EMSA). mRNA expressions of cytokines were identified by semi-quantitative assay, reverse transcriptase- polymerase chain reaction (RT-PCR). RESULTS: Three patients (20%) in the BIFICO group had relapses during 2-mo follow-up period, compared with 14 (93.3%) in placebo group (P<0.01). The concentration of fecal lactobacilli, bifidobacteria was significantly increased in BIFICO-treated group only (P<0.01). The expressions of NF-kappaB p65 and DNA binding activity of NF-kappaB were significantly attenuated in the treatment group than that in control (P<0.05). The mRNA expression of anti-inflammatory cytokines was elevated in comparison with the control group. CONCLUSION: The probiotic could impede the activation of NF-kappaB, decrease the expressions of TNF-alpha and IL-1beta and elevate the expression of IL-10. These results suggest that oral administration of this new probiotic preparation is effective in preventing flare-ups of chronic UC. It may become a prophylactic drug to decrease the relapse of UC.

Anti-Inflammatory Agents, Non-Steroidal↗

Oxidative stress induced by lead, cadmium and arsenic mixtures: 30-day, 90-day, and 180-day drinking water studies in rats: an overview.

Humans are frequently exposed to combinations of lead (Pb), cadmium (Cd) and Arsenic (As) but there is a paucity of actual data on the molecular effects of these agents at low dose levels. The present factorial design studies were undertaken in rats to examine the effects of these agents at LOEL dose levels on a number of molecular parameters of oxidative stress in hematopoietic and renal organ systems following oral exposure in drinking water at 30, 90 and 180 day time points. Results of these studies demonstrated dynamic, time-dependent alterations in both molecular targets and inducible oxidative stress protective systems in target cell populations. In general, cellular protective systems, which protected against oxidative damage at the 90 day time point, appeared to be finite such that molecular manifestations of oxidative stress became statistically significant at the 180 day time point for several of the combination exposure groups. These data demonstrate the importance of duration of exposure in assessing the toxic potential of Pb, Cd and As mixtures at low dose levels.

Aminolevulinic Acid↗

A quantitative structure-property relationship for predicting drug solubility in PEG 400/water cosolvent systems.

PURPOSE: A quantitative structure-property relationship (QSPR) was developed to predict drug solubility in binary mixtures of polyethylene glycol (PEG) 400 and water. The ability of the QSPR model to predict solubility was assessed and compared to the classic log-linear cosolvency model. METHODS: The solubility of 122 drugs, ranging in log P from -2.4 to 7.5, was determined in 0%, 25%, 50%, and 75% PEG (v/v in water) by the shake-flask method. Solubility data from 84 drugs were fit by linear regression using the following molecular descriptors: molecular weight, volume, radius of gyration, density, number of rotatable bonds, hydrogen-bond donors, and hydrogen-bond acceptors. The multiple linear regression model was optimized by a genetic algorithm guided selection method. The remaining 38 compounds were used to test the predictability of the model. RESULTS: QSPR-based models developed at each volume fraction with the training set compounds showed a reasonable correlation coefficient (r) of approximately 0.9 and a root mean square (rms) error of <0.5 log unit. The model predicted solubility values of approximately 78% of the testing set compounds within 1 log unit. The log-linear model was as effective as the QSPR-based model in predicting the testing set solubilities; however, many drugs, as expected, showed significant deviation from log-linearity. CONCLUSIONS: The QSPR model requires only the chemical structure of the drug and has utility for guiding vehicle identification for early preclinical in vivo studies, especially when compound availability is limited and experimental data such as aqueous solubility and melting point are unknown. When experimental data are available, the log-linear model was verified to be a useful predictive tool.

Models, Chemical↗

Miniature device for aqueous and non-aqueous solubility measurements during drug discovery.

PURPOSE: A miniature device was developed for the measurement of aqueous and non-aqueous equilibrium solubility during drug discovery. The solubility values obtained using the miniature device were compared to those obtained using the conventional shake-flask method. METHODS: The aqueous solubility of six structurally diverse compounds, the solubility of carbamazepine in various cosolvent systems, and the pH-solubility profile of saquinavir were determined using the miniature device. The device contains a multichannel cartridge pump and a Tygon tubing that is mounted on the pump with two ends linked by a syringe filter. The drug slurry was filled into the tubing and circulated inside, continually passing through the syringe filter. At the end of the experiment, the filtrate was collected and analyzed directly by High-Pressure Liquid Chromatography (HPLC). The solubility was also determined by the shake-flask method. RESULTS: The solubility values determined by the miniature device were in good agreement with those measured by the conventional shake-flask method. CONCLUSIONS: The miniature device provides a unique way of testing aqueous and non-aqueous equilibrium solubility in a microscale setting. With approximately 1 mg of compound, it is possible to determine the entire pH-solubility profile. The device is useful for solubility screening during lead optimization and candidate selection in early drug discovery, when compound supply is limited. It can also be used for screening solubility in non-aqueous systems to select vehicles for preclinical in vivo studies.

Anti-HIV Agents↗

Prediction of aqueous solubility of organic compounds using a quantitative structure-property relationship.

A quantitative structure-property relationship (QSPR) was developed for predicting the aqueous solubility of drug-like compounds from their chemical structures. A set of 321 structurally diverse drugs or related compounds, with their intrinsic aqueous solubility collected from literature, was used in this analysis. The data were divided into a training set (n = 267) for building the model and a randomly chosen testing set (n = 54) for assessing the predictive ability of the model. A series of molecular descriptors was calculated directly from chemical structures and a set of eight descriptors, including dipole moment, surface area, volume, molecular weight, number of rotatable bonds/total bonds, number of hydrogen-bond acceptors, number of hydrogen-bond donors and density, was chosen for the final model. The eight-descriptor model generated by multiple linear regression was further optimized by a genetic algorithm guided selection method. The model has a correlation coefficient (r) of 0.95 and a root-mean-square (rms) error of 0.56 log unit. It predicts the solubility of testing set compounds with a reasonable degree of accuracy (r = 0.84 and rms = 0.86 log unit). The present model can serve as a tool for medicinal chemists to guide their early synthetic efforts in arriving at appropriate analogs.

Algorithms↗

Delivery of Nerve Growth Factor to the Brain via the Olfactory Pathway.

Purpose: To assess the potential of delivering nerve growth factor (NGF) to the brain along the olfactory neural pathway for the treatment of Alzheimer's disease. Methods: Recombinant human NGF (rhNGF) was given as nose drops to anesthetized rats. The rhNGF concentrations in the brain were determined by enzyme-linked immunosorbent assay (ELISA). Results: Following olfactory administration, rhNGF reached the brain within an hour, achieving a concentration of 3400 pM in the olfactory bulb, 660–2200 pM in other brain regions and, 240 pM and 180 pM in the hippocampus and the amygdala, respectively. In contrast, little or no rhNGF was found in the brain following intravenous administration. Conclusions: A significant amount of rhNGF can be delivered to the brain via the olfactory pathway. The detection of rhNGF by ELISA indicates that rhNGF is delivered to the brain relatively intact. The rapid appearance of rhNGF in the brain suggests that it may be transported by an extraneuronal route into the brain via intercellular clefts in the olfactory epithelium. Further work to clarify the transport mechanism is underway. The olfactory pathway is a promising, non-invasive route for drug delivery to the brain, which has potential for the treatment of neurodegenerative diseases including Alzheimer's disease.

Journal Article↗

Induction of apoptosis of lymphocytes in rat mucosal immune system.

AIM:To undergo apoptosis during negative and positive selection processes in rat mucosal immune system which are implicated in the pathogenesis of various mucosal diseases.METHODS: Female Sprague-Dawley rats were given protein synthesis inhibitor, cycloheximide, intravenously or intraperitoneally, an apoptosis was recognized by morphological hallmark under light and electronmicroscopy, and the expression of proliferating cell nuclear antigen was visualized immunohisto-chemically.RESULTS: The apoptosis of mucosal lymphocytes in the digestive tract, as well as in trachea, uterus and lacrimal gland was induced by cycloheximide (>1.0mg·kg(-1) body weight), which were located mainly in lamina propria and germinal centers of lymphoid nodules. At the same time, a portion of crypt epithelial cells of proliferating zone in small and large intestine, and the epithelial cells in genital tract were also found to undergo apoptosis. Immunostainings showed that apoptotic cells expressed proliferating cell nuclearantigen.CONCLUSION: Apo-ptosis of lymphocytes in mucosal immune system can be induced by cycloheximide. This model will facilitate the understanding of normal mucosal immune system and its role in the pathogenesis of related diseases such as inflammatory bowel diseases.

Journal Article↗

In silico ADME/Tox: why models fail.

By way of example, we discuss the apparent 'failure' of in silico ADME/Tox models and attempt to understand the causes. Often, the interpretation of the success of models lies in their use and the expectations of the user. Other times, models are, in fact, of little value. Disappointing results can be linked to the key aspects of the model and modeling procedure, many of these related to the original data and its interpretation. We make recommendations to providers of models regarding the development, description, and use of models as well as the data and information that are important to understanding a model's quality and scope of use.

Carrier Proteins↗