Biomedical subjects

L Jia

Publications and source records attributed to L Jia.

At least 37 records · Page 2Linked to original sources

PubMed2001

Stacking and separation of coproporphyrin isomers by acetonitrile-salt mixtures in micellar electrokinetic chromatography.

The effectiveness of the addition of salt and acetonitrile in the sample matrix to induce narrowing of the analyte zones is demonstrated for the first time in micellar electrokinetic chromatography (MEKC). Using coproporphyrin (CP) I and III isomers as test compounds, the use of sodium cholate (SC) as the micelle in the separation buffer and a high concentration of sodium chloride in the aqueous sample solution (without the presence of an organic solvent) were found to provide enhancement in peak heights for both CP I and III, but yielded very poor resolution of these two positional isomers at sample size of 10% capillary volume or larger. With the addition of acetonitrile as the organic solvent in the aqueous sample solution (acetonitrile-salt mixtures), baseline/partial resolution of CP I and III was obtained even at large injection volumes, along with significant increase in peak heights for both isomers. Possible mechanisms responsible for the narrowing of analyte zones are briefly discussed. The effects of experimental parameters, such as concentrations of salt and acetonitrile, on peak heights and resolution of the test compounds were studied. Importantly, the usefulness of the present method was demonstrated for the MEKC determination of endogenous CP I and III present in normal urine samples with good separation and detection performances.

Acetonitriles↗

PubMed2001

Comprehensive resource: Skeletal gene database.

The Skeletal Gene Database (SGD) is an integrated resource that provides comprehensive information about bone-related genes, mRNA, and proteins expressed in human and mouse, with rich links to numerous other electronic tools. SGD contains expressed sequence tag (EST) data from all the skeletal-related cDNA libraries that are available to the public. It supplies the query/data access analytic tools for users to search and compare each gene expressed in skeletal tissue(s). The results derived from EST tissue expression profiling will allow users to get the data on the mRNA copy numbers of each gene expressed in each tissue and its normalized value. From the SGD, researchers can obtain information regarding the name, symbol, size, exon/intron number, chromosomal location, LocusLink, and related disease (if any is known) of each gene. This electronic compendium also furnishes information on the protein of the corresponding gene including the protein size (amino acid number and molecular weight). It provides swift and ready access to other useful databases including OMIM, UniGene and PUBMED. The data will be updated regularly in step with current and future research, thereby providing what we hope will serve as a highly useful source of information and a powerful analytic tool to the scientific community.

Animals↗

PubMed2001

8-Cl-adenosine mediated cytotoxicity and sensitization of T-lymphoblastic leukemia cells to TNFalpha-induced apoptosis is via inactivation of NF-kappaB.

These data show that 8-Cl-cAMP is cytotoxic to the lymphoblastic leukemia cell line CEM and its vinblastine selected multidrug resistant derivative, CEM/VLB100 although PKA was not involved in these effects. The cytotoxic effects of 8-Cl-cAMP was abrogated by cotreatment with either ADA or IBMX which indicated a degradation form of 8-Cl-cAMP was needed for this cytotoxicity. CEM and CEM/VLB100 cells displayed a notable sensitivity to 8-Cl-adenosine-induced growth inhibition and apoptosis. 8-Cl-adenosine increased the cytosolic levels of IkappaBalpha which prevented NF-kappaB nuclear translocation. 8-Cl-adenosine also prevented TNFalpha-induced IkB decay and NF-kappaB activation in CEM and CEM/VLB100 cells.

2-Chloroadenosine↗

PubMed2001

Acute and subacute toxicity and efficacy of S-nitrosylated captopril, an ACE inhibitor possessing nitric oxide activities.

The toxicity and efficacy of S-nitrosocaptopril (CapNO), a novel vasodilator possessing the capacities of both a nitric oxide donor and an angiotensin converting enzyme (ACE) inhibitor, were examined in rodents. In single-dose acute toxicity studies in ICR mice, the median lethal dose (LD(50)) for CapNO was 674+/-94 mg/kg (iv) and 2078+/-100 mg/kg (po), whereas for oral captopril was 4286+/-173 mg/kg. S-nitrosoglutathione, containing the same S-nitroso moiety as CapNO, showed an LD(50) equal to CapNO when the values were expressed by the mol/kg. The cause of acute death by the high doses of CapNO was lethal hypotension. In the subacute toxicity studies, oral CapNO was well tolerated in normotensive and hypertensive rats at doses up to 500 mg/kg/day for 3 months, except for considerable reductions in food consumption and growth rate observed in the 500 mg/kg/day group. Serum chemistry and hematology tests performed in the subacute toxicity studies revealed no adverse effects of oral CapNO except for a significant decrease in cholesterol levels in hypertensive SHR rat. At autopsy, no histopathological changes in major organs were observed over the subacute period. Administration of a therapeutic dose of CapNO (iv, 250 microg/kg which produced 25% decreases in blood pressure) revealed no changes in the hematological parameters. Subchronic treatment of SHR and SS/Jr rats with oral CapNO (50 mg/kg/day) significantly reduced mean arterial pressure to the normotensive level. Considering the absence of adverse effects of CapNO in the subchronic toxicity study, CapNO appears to be a safe drug for further clinical trials, but particular caution must be taken because it can cause hypotension when overdosed.

Administration, Oral↗

PubMed2001

Quantitative determination of apoptosis on leukemia cells by infrared spectroscopy.

Quantitation of apoptotic cell death in vivo has become an important issue for patients with acute leukemia. We describe herein a new analytical method, based on infrared (IR) spectroscopy, to estimate the percentage of apoptotic leukemic cells in two different cell lines (CEM and K562), induced with etoposide (VP-16). As the percentage of apoptosis increases, the protein structure shifts from dominantly beta-sheet to unordered (random coil), the overall lipid content increases and the amount of detectable DNA decreases. These changes can be directly related to the percentage of apoptosis as determined by two standard reference methods: flow cytometry and DNA ladder formation. The correlation between the significant IR spectral changes and the percentage of apoptotic leukemia cells in the two cell lines was optimal up to 24 h following etoposide treatment (r = 0.99 for CEM cells and r = 0.96 for K562 cells). Furthermore, IR spectroscopy is able to detect apoptotic changes in these cells already after 4 h treatment with VP-16, compared to flow cytometry which needs 6 h to observe significant changes. Our study suggests that IR spectroscopy may have potential clinical utility for the early, fast and reagent free assessment of chemotherapeutic efficacy in patients with leukemia.

Apoptosis↗

PubMed2001

In vitro and in vivo assessment of cellular permeability and pharmacodynamics of S-nitrosylated captopril, a nitric oxide donor.

1. The present studies were aimed at testing the hypothesis that S-nitrosylated captopril (CapNO), a novel crystalline nitric oxide (NO) donor, readily permeates both in vitro and in vivo endothelial monolayers, resulting in its pharmacodynamic effects. 2. CapNO and Captopril (Cap) were added to apical side of endothelial monolayers formed on microporous membranes, and the permeated drugs were collected from basolateral side and detected by a HPLC method. The permeability coefficient (P(app); cm sec(-1)) of CapNO across the endothelial monolayers was 6.0 x 10(-5), higher than that of Cap (3.13 x 10(-5)), indicating the enhancement effect of the attached NO group in CapNO on cellular permeability. The P(app) of CapNO and Cap across Caco-2 cells were 3.15 x 10(-5) and 1.53 x 10(-5), respectively. The low P(app) of CapNO to Caco-2 cells may be attributed to the high membrane resistance of Caco-2 cells. 3. A bolus injection of CapNO to epicardial coronary artery of chronically-instrumented awake dogs caused significant increases in coronary blood flow and coronary diameters dose-dependently without significant changes in aortic pressure. In contrast, the equimolar doses of Cap did not produce haemodynamic responses. 4. Intravenous CapNO caused an instant increase in the regional cerebral blood flow determined by H(2)-clearance, whereas the equimolar doses of Cap did not enhance the cerebral blood flow. 5. These results conclude that the NO group, an active component of CapNO, enhances both in vitro and in vivo endothelial permeability to the entire compound, resulting in instant increases in blood flow and vascular diameters. In contrast, the equimolar Cap does not have the instant vascular effects.

Animals↗

PubMed2001

Generation of reactive oxygen species is not involved in idarubicin-induced apoptosis in human leukaemic cells.

The anthracycline antibiotic idarubicin (IDA) induces double-stranded DNA breaks, the generation of reactive oxygen species (ROS) and apoptosis in human leukaemic cells. It is unclear whether the generation of ROS is associated with the apoptotic process. Using the T-lymphoblastic leukaemic CEM cell line, we found that IDA-induced DNA breaks were correlated with final cell death. The reduction in mitochondrial membrane potential (Deltapsim) and the generation of ROS occurred simultaneously with IDA-induced activation of caspase-9 and caspase-3. Inhibition of caspases by a pan-caspase inhibitor, benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone (Z-VAD-fmk) completely blocked IDA-induced reduction of Deltapsim, apoptosis and final cell death. Interestingly, ROS generation was significantly enhanced by Z-VAD-fmk. ROS generation was neither caspase dependent nor part of the apoptotic process. IDA-mediated reduction in Deltapsim is caspase dependent and is not a consequence of the generation of ROS. These results indicate that IDA-induced generation of ROS and apoptosis are separate events. Inhibition of caspases facilitates IDA-mediated generation of ROS.

Amino Acid Chloromethyl Ketones↗

PubMed2001

Biostability and pharmacokinetics of LJP 920, an octameric Gal (alpha1-3) Gal conjugate for the inhibition of xenotransplantation rejection.

Antibodies to an alpha-galactosyl saccharide structure present in human serum are associated with hyperacute rejection and delayed xenograft rejection after pig-to-primate xenotransplantation. To overcome this major barrier to the xenotransplantation, LJP 920, a galactosyl alpha1-3 galactose (Gal (alpha1-3) Gal) coupled to a non-immunogenic platform at a valency of eight Gal (alpha1-3) Gal molecules/platform, was synthesized to clear circulating antibodies and to inhibit their production by B cells that produce these antibodies. Herein we report on the stability of UP 920 in biological media and its pharmacokinetic profile. Incubation of LJP 920 with mouse serum or liver microsomes at 37 degrees C for 2 days showed no indication of degradation of the conjugate as detected by a reversed-phase HPLC method, indicating that the conjugate is not subject to enzymatic metabolism. After intravenous administration of LJP 920 to mice at the doses of 20 and 100 mg kg(-1), UP 920 serum concentration decreased rapidly, showing a biphasic pattern, with a distribution half-life of 3 min and an elimination half-life of more than 30 min, respectively. The serum-to-erythrocyte concentration ratio of UP 920 was 33- and 36-fold excess at 0.5 and 5 min, respectively, after intravenous administration (100 mg kg(-1)). Both Cmax and AUC values increased in a dose-proportional manner. UP 920 displayed a great distribution to well-perfused tissues. It was eliminated mainly through renal excretion in the unchanged form, which accounted for 23% of the total amount within 8 h of dosing.

Animals↗

PubMed2001

Targeted disruption of semaphorin 3C leads to persistent truncus arteriosus and aortic arch interruption.

Semaphorin 3C is a secreted member of the semaphorin gene family. To investigate its function in vivo, we have disrupted the semaphorin 3C locus in mice by targeted mutagenesis. semaphorin 3C mutant mice die within hours after birth from congenital cardiovascular defects consisting of interruption of the aortic arch and improper septation of the cardiac outflow tract. This phenotype is similar to that reported following ablation of the cardiac neural crest in chick embryos and resembles congenital heart defects seen in humans. Semaphorin 3C is expressed in the cardiac outflow tract as neural crest cells migrate into it. Their entry is disrupted in semaphorin 3C mutant mice. These data suggest that semaphorin 3C promotes crest cell migration into the proximal cardiac outflow tract.

Amino Acid Sequence↗

PubMed2001

PlexinA2 and semaphorin signaling during cardiac neural crest development.

Classic studies using avian model systems have demonstrated that cardiac neural crest cells are required for proper development of the cardiovascular system. Environmental influences that perturb neural crest development cause congenital heart defects in laboratory animals and in man. However, little progress has been made in determining molecular programs specifically regulating cardiac neural crest migration and function. Only recently have complex transgenic tools become available that confirm the presence of cardiac neural crest cells in the mammalian heart. These studies have relied upon the use of transgenic mouse lines and fate-mapping studies using Cre recombinase and neural crest-specific promoters. In this study, we use these techniques to demonstrate that PlexinA2 is expressed by migrating and postmigratory cardiac neural crest cells in the mouse. Plexins function as co-receptors for semaphorin signaling molecules and mediate axon pathfinding in the central nervous system. We demonstrate that PlexinA2-expressing cardiac neural crest cells are patterned abnormally in several mutant mouse lines with congenital heart disease including those lacking the secreted signaling molecule Semaphorin 3C. These data suggest a parallel between the function of semaphorin signaling in the central nervous system and in the patterning of cardiac neural crest in the periphery.

Animals↗

PubMed2001

[Analysis, prospect and treatment of causes of phacoemulsification complications].

OBJECTIVE: To analyse the causes of different complications of phacoemulsification and to investigate their principles of treatment and prevention. METHOD: The causes of different complications in 187 (180 cases) of 2,250 eyes having undergone phacoemulsification were analyzed. RESULTS: Intraoperatively, the common complications of phacoemulsification were posterior capsular rupture in 70 eyes (3.1%), iris damage in 16 eyes (0.7%), iris prolapse in 6 eyes (0.3%), drop of lens fragments into vitreous in 3 eyes (0.1%) and tear of Descernent's membrane in 4 eyes (0.2%). The common complications after the operation were corneal endothelial edema in 89 eyes (4.0%), corneal decompensation in 2 eyes (0.1%), temporary intraocular hypertension in 28 eyes (1.2%), pupillary dilatation in 7 eyes (0.3%), retinal detachment in 8 eyes (0.4%), cystoid macular edema in 24 eyes (1.1%) and displacement of intraocular lens in 8 eyes (0.4%). CONCLUSIONS: The different complications can be diminished following the popularization and development of phacoemulsification. It should be properly managed once the complication has occurred, and good operative effects can be obtained.

Eye Diseases↗

PubMed2001

Recording of spared motor evoked potentials and its augmentation by 4-aminopyridine in chronic spinal cord-injured rats.

OBJECTIVE: To research the direct electrophysiological evidence of discomplete spinal cord injury (SCI) and the effect of 4-aminopyridine on it. METHODS: Motor evoked potentials (MEPs), both spinal cord recorded MEPs (scMEPs) and extracellularly recorded MEPs (exMEPs) were recorded and characterized on a T13 epidural electrode (scMEPs) and an extracellular microelectrode (exMEPs) for 10 normal rats and 40 rats with lesions of various severity (sham, 35 g.cm force (gcf), 70 gcf, 100 gcf impact injury) at the T8-T9 cord using the Allen's drop model. The incline plane and Tarlov techniques were used to assess clinical neurological function. RESULTS: MEPs in the normal rats were elicited by applying transcortical suprathreshold stimulation consisting of 3-4 early negative peaks (N1, N2, N3 and N4) followed by several late waves. The N1 and N2 peaks were largest in the anterior and ventrolateral funiculus, respectively, which was indicative of extrapyramidal pathways. The 100 gcf impact injuries and the cord transection abolished the MEP distal to the lesion, whereas the 35 gcf injuries resulted in a latency shift and amplitude decrement of the MEP peaks. Eighteen of the 20 rats with 70 gcf-injuries showed clinical paraplegia. Among them, 7 rats had neurophysiological evidence of residual conduction pathways through the lesioned cord segment, such as the presence of N1 and N2 peaks in the scMEPs or exMEPs. After 4-aminopyridine (4-AP) administrations (1 mg/kg), the amplitude of the spared exMEP increased significantly and spread more widely. CONCLUSIONS: MEPs evoked by transcortical stimulation travel mostly in the extrapyramidal tract. MEP monitoring could provide an excellent method of detecting the functional integrity of the motor tracts after SCI, and could even detect spared motor fibers after discomplete SCI. Furthermore, the use of 4-AP or other K+ channel blocking agents may be a potential treatment for patients with chronic moderate to severe SCI.

4-Aminopyridine↗

PubMed2001

The relationship between cartilage end-plate calcification and disc degeneration: an experimental study.

OBJECTIVE: To study the relationship between cartilage end-plate calcification and intervertebral disc degeneration. METHODS: An experimental model of cervical disc degeneration in rabbits was established by resection of the cervical supraspinous and interspinous ligaments and detachment of the posterior paravertebral muscles from the cervical vertebrae. Mechanical instability in the cervical spine elicited by this surgical intervention accelerated the process of intervertebral disc degeneration. The extent of intervertebral disc degeneration was graded in morphologically, and the thicknesses of the calcified layer and the uncalcified layer of the cartilage end-plate were measured in each degenerated cervical disc. RESULTS: In less severely degenerative cervical discs, the morphology of the cartilage end-plate showed nearly normal construction, and the tidemark was clear. In severely degenerative discs, the matrix and cells showed fibrosis, the tidemark advanced, and the calcified cartilage thickened. There exists a positive correlation between the thickness of the calcified layer of the cartilage end-plate and the degree of cervical disc degeneration. CONCLUSION: The calcification of the cartilage end-plate is the key factor that initiates and promotes cervical disc degeneration.

Animals↗

PubMed2001

[A study on effective parameters to represent the heterogeneity in ventricular repolarization].

The aim of this study was to investigate whether ARI (activation-recovery interval) dispersion on the sheep epicardium was related with the ischemia induced heterogeneity in ventricular repolarization. We have developed an algorithm based on wavelet transformation to analyze ARI from a 64-channel epicardial ECG data of an ischemic sheep. The quadratic spline wavelet was used to extract QRS with 2(1) scale and T wave with 2(5) scale, and then A and R points were determined by definition. It was found that there was not a significant difference in the average ARI on the epicardium before and during ischemia. Meanwhile ARI dispersion on the epicardium was significantly increased during ischemia (126.3 ms vs 59.9 ms, P = 0.0007). Furthermore, a computer simulation showed that ARI is very close to ADP, suggesting that ARI dispersion may be an effective parameter to estimate the heterogeneity in ventricular repolarization induced by ischemia.

Action Potentials↗

PubMed2001

[Phacoemulsification for short eye axis cataract].

OBJECTIVE: To analyze the operative difficulty of cataract phacoemulsification in an eye with shorter axial length and discuss its preventive measures. METHODS: A retrospective study was performed to analyze the 122 patients (143 eyes) who had undergone cataract phacomulsification. Their ocular axial lengths were 20.21 to 22.10 mm. RESULTS: Because these patients had shorter ocular axis, shallower anterior chamber depth, narrower space in the anterior ocular segment and higher vitreous pressure, the operation was hard to perform. The rate of posterior capsular rupture was 7.69%. The postoperative inflammatory reaction was severe. The rate of reversible corneal edema (29.37%) was obviously higher than that in cataractous eyes with normal ocular axis (6.7%, P < 0.01), and also higher than that in eyes with normal ocular axis and hard nucleus (12.5%, P < 0.05). CONCLUSIONS: It is emphasized that the correct technique of incision, application of chopping and breaking nucleus technique, lower energy and higher aspiration for effective phacoemulsification with the help of Viscoat viscoelastic material and maintenance of deep anterior chamber are the key procedures to obtain satisfactory operative results.

Adult↗

PubMed2001

[Prevalence of cataract and surgical coverage among adults aged 50 or above in Shunyi District of Beijing, China].

OBJECTIVE: To estimate the prevalence of cataract, surgical coverage rate and the bilateral cataract-blindness burden among adults aged 50 or above in Shunyi District of Beijing, China, for evaluating the cataract status and the efficacy of the prevention blindness program in more than 10 years. METHODS: Cluster sampling was used in randomly selected individuals aged 50 years or older in 28 villages in Shunyi District in fall, 1996. 5 084 individuals received visual acuity test and eye examination, including lens examination by slit lamp. The cataract operation status was also evaluated. RESULTS: The prevalence of cataract was 23.31% among adults aged 50 or above. The prevalence of cataract was increasing by aging. The prevalence of cataract in women and illiterates was significantly higher statistically. The cataract surgical rate had been increasing since 1984. When the bilateral pinhole vision < 3/60 was defined as the blindness criterion, the cataract blindness surgical coverage rate was 56.36%, and the bilateral cataract-blindness burden was 1.63%. When the bilateral presenting vision < 6/60 was defined as the blindness criterion, the cataract blindness surgical coverage rate was 47.79%, and the bilateral cataract-blindness burden was 2.22%. The cataract surgical coverage rates were much lower and the bilateral cataract-blindness burden much higher in women, illiterates and persons aged 70 or above. CONCLUSIONS: The prevalence of cataract is higher and bilateral cataract-blindness burden is heavier in elder individuals. Cataract blindness is still a serious public health problem in elder, women and illiterates after the prevention blindness program having been actively conducted for more than ten years.

Aged↗

PubMed2000

A biosensor assay for studying ligand-membrane receptor interactions: binding of antibodies and HIV-1 Env to chemokine receptors.

The HIV envelope (Env) protein mediates entry into cells by binding CD4 and an appropriate coreceptor, which triggers structural changes in Env that lead to fusion between the viral and cellular membranes. The major HIV-1 coreceptors are the seven transmembrane domain chemokine receptors CCR5 and CXCR4. The type of coreceptor used by a virus strain is an important determinant of viral tropism and pathogenesis, and virus-receptor interactions can be therapeutic targets. However, Envs from many virus strains interact with CXCR4 and CCR5 with low affinity such that direct study of this important interaction is difficult if not impossible using standard cell-surface binding techniques. We have developed an approach that makes it possible to study ligand binding to membrane proteins, including Env-coreceptor interactions, using an optical biosensor. CCR5, CXCR4, and other membrane proteins were incorporated into retrovirus particles, which were purified and attached to the biosensor surface. Binding of conformationally sensitive antibodies as well as Env to these receptors was readily detected. The equilibrium dissociation constant for the interaction between an Env derived from the prototype HIV-1 strain IIIB for CXCR4 was approximately 500 nM, explaining the difficulty in measuring this interaction using standard equilibrium binding techniques. Retroviral pseudotypes represent easily produced, stable, homogenous structures that can be used to present a wide array of single and multiple membrane-spanning proteins in a native lipid environment for biosensor studies, thus avoiding the need for detergent solubilization, purification, and reconstitution. The approach should have general applicability and can be used to correlate Env-receptor binding constants to viral tropism and pathogenesis.

Animals↗

PubMed2000

Double FYVE-containing protein 1 (DFCP1): isolation, cloning and characterization of a novel FYVE finger protein from a human bone marrow cDNA library.

Double FYVE-containing protein 1 (DFCP1) encodes a 777 amino acid protein that contains: (1) an N-terminal Cys-His cluster with some homology to many zinc finger domains; (2) a consensus sequence consistent with an ATP/GTP binding site; and (3) a C-terminal domain unique because it contains two zinc-binding FYVE domains. The gene, ZNFN2A1 (GenBank accession no. AF251025) was localized to chromosome 14q22-q24 and shown to be composed of 11 exons. Northern blot analysis revealed the presence of three different mRNA transcripts (4.2, 3 and 1.2kb). The two longer transcripts appear to be expressed in a variety of different tissues, especially in endocrine tissues, while the shorter messenger is limited to testis. Both of the larger transcripts are unusual due to the presence of a 463bp long 5' UTR. Furthermore, the 4.2kb transcript contains a non-standard polyadenylation consensus sequence while the 3kb transcript contains a standard consensus sequence but within the open reading frame. Following in vitro transfection of a DFCP1-containing expression construct, confocal microscopy studies showed a vesicular distribution of DFCP1 suggesting that this protein, like other FYVE-containing proteins, might be involved in membrane trafficking.

3T3 Cells↗