Biomedical subjects

X Cai

Publications and source records attributed to X Cai.

At least 91 records · Page 5Linked to original sources

PubMed2000

[Determination of the mixed soporific by infrared subtractive spectroscopy technique].

A software of subtractive spectroscopy is provided on the NICOLET FTIR-560 infrared spectrometer. Some complicated processes of separation can be avoided by using the subtractive spectroscopy technique which simplifies the analytical procedure. An excellent infrared spectrum of a single component in a complex mixture is obtained successfully in this paper. By analysing and searching spectrum, the structures of the main components of the mixed soporific have been identified and it also improved the accuracy of appraising.

Diazepam↗

PubMed2000

[Autologous tissue engineered skin for full thickness skin replacement].

OBJECTIVE: To evaluate the feasibility of regenerating or repairing damaged skin utilizing tissue engineering techniques. MATERIALS AND METHODS: Yorkshire pigs were used in the study. A critical size defect of six, full thickness, 4 cm in diameter round wounds, which were marked on the paravertebral region of the animal were excised. The skin defects were randomly divided into three groups. Group I as control group received no cells or polymer. Group II as a second control group received pluronic hydrogel with no cells. Group III as the experimental group received a mixture of cells (keratinocytes and fibroblasts) and pluronic hydrogel. All specimens were harvested at 4 and 6 weeks in vivo, and underwent gross, histological, and transmission electron microscope evaluation. RESULTS: Histologically, the skin in the experimental group was similar to normal skin with stratified epidermis overlying a moderately thick collageneous dermis. The interface of the tissue was apparently demarcated by epidermal ridges and dermal papillae. The control groups showed no skin formation except for granulation with infiltrating inflammatory cells in the wound. Transmission electron microscopy showed that the basal lamina of the experimental group was well developed and attached to the extracellular matrix. CONCLUSION: This finding demonstrates the successful use of tissue engineered skin with Pluronic F-127 as a cell carrier.

English Abstract↗

PubMed1999

Simultaneous quantitation of etoposide and its catechol metabolite in human plasma using high-performance liquid chromatography with electrochemical detection.

Etoposide, a highly active and widely used antineoplastic agent, is O-demethylated to its active catechol metabolite. A high-performance liquid chromatographic assay method for the simultaneous quantitation of etoposide and etoposide catechol in human plasma was established. Etoposide and etoposide catechol were extracted from plasma using chloroform and methanol followed by phase separation, evaporation of the organic phase, and reconstitution of the residue. Chromatography was accomplished using a reversed-phase phenyl analytical column (390 mm x 3.9 mm I.D.) with a mobile phase of 76.6% 25 mM citric acid-50 mM sodium phosphate (pH 2.4)-23.4% acetonitrile pumped isocratically at 1 ml/min with electrochemical detection. The limit of detection for etoposide was 1.2 nM and for etoposide catechol was 0.2 nM. The precision (CV) for etoposide ranged from 0.7 to 3% and for the catechol metabolite from 1 to 6%; accuracy of predicted values ranged from 97 to 106% and 94 to 103%, respectively. The assay was linear from 0.1 to 10 microM for etoposide and from 0.005 to 0.5 microM for etoposide catechol in plasma. Recovery of etoposide and etoposide catechol ranged from 93 to 95% and 90 to 98%, respectively. Stability of etoposide and etoposide catechol in human plasma containing ascorbic acid stored at -70 degrees C for one year was demonstrated. This assay procedure is suitable for evaluation of etoposide and etoposide catechol pharmacokinetics in plasma following etoposide administration.

Antineoplastic Agents, Phytogenic↗

PubMed1999

Apoptosis and growth inhibition in malignant lymphocytes after treatment with arsenic trioxide at clinically achievable concentrations.

BACKGROUND: Arsenic trioxide (As2O3) can induce clinical remission in patients with acute promyelocytic leukemia via induction of differentiation and programmed cell death (apoptosis). We investigated the effects of As2O3 on a panel of malignant lymphocytes to determine whether growth-inhibitory and apoptotic effects of As2O3 can be observed in these cells at clinically achievable concentrations. METHODS: Eight malignant lymphocytic cell lines and primary cultures of lymphocytic leukemia and lymphoma cells were treated with As2O3, with or without dithiothreitol (DTT) or buthionine sulfoximine (BSO) (an inhibitor of glutathione synthesis). Apoptosis was assessed by cell morphology, flow cytometry, annexin V protein level, and terminal deoxynucleotidyl transferase labeling of DNA fragments. Cellular proliferation was determined by 5-bromo-2'-deoxyuridine incorporation into DNA and flow cytometry and by use of a mitotic arrest assay. Mitochondrial transmembrane potential (delta psi(m)) was measured by means of rhodamine 123 staining and flow cytometry. Protein expression was assessed by western blot analysis or immunofluorescence. RESULTS: Therapeutic concentrations of As2O3 (1-2 microM) had dual effects on malignant lymphocytes: 1) inhibition of growth through adenosine triphosphate (ATP) depletion and prolongation of cell cycle time and 2) induction of apoptosis. As2O3-induced apoptosis was preceded by delta psi(m) collapse. DTT antagonized and BSO enhanced As2O3-induced ATP depletion, delta psi(m) collapse, and apoptosis. Caspase-3 activation, usually resulting from delta psi(m) collapse, was not always associated with As2O3-induced apoptosis. As2O3 induced PML (promyelocytic leukemia) protein degradation but did not modulate expression of cell cycle-related proteins, including c-myc, retinoblastoma protein, cyclin-dependent kinase 4, cyclin D1, and p53, or expression of differentiation-related antigens. CONCLUSIONS: Substantial growth inhibition and apoptosis without evidence of differentiation were induced in most malignant lymphocytic cells treated with 1-2 microM As2O3. As2O3 may prove useful in the treatment of malignant lymphoproliferative disorders.

Adenosine Triphosphate↗

PubMed1999

Localization of the olfactory cyclic nucleotide-gated channel subunit 1 in normal, embryonic and regenerating olfactory epithelium.

The spatial and temporal expression of subunit 1 of the olfactory cyclic nucleotide-gated channel was investigated using affinity-purified anti-fusion protein antibodies. Immunoreactivity was most prominent in the ciliary layer of the olfactory epithelium, but high protein expression was also seen along the entire length of olfactory receptor neuronal axons to the level of the glomeruli. Electron microscopy showed that the long, thin distal compartments of olfactory cilia labeled more prominently than their thicker proximal segments. This was true as soon as these distal parts began to develop. Using light microscopy, developmental expression of olfactory cyclic nucleotide-gated channel subunit 1 could be detected in discrete populations of olfactory receptor neurons by embryonic day 14. Other signaling molecules are expressed either later (Golf) or only at the level of the epithelial surface and not in axons (adenylyl cyclase type III). Following unilateral lesions of the olfactory bulb, olfactory cyclic nucleotide-gated channel subunit 1 immunoreactivity was present early and throughout developing olfactory receptor neurons; adenylyl cyclase type III immunoreactivity, in contrast, was detectable only later, and again present only in the cilial layer. These results support the hypothesis that this subunit of the olfactory cyclic nucleotide-gated channel may be involved in olfactory axon guidance, in addition to its well-described role in olfactory signal transduction.

Adenylyl Cyclases↗

PubMed1999

Tissue factors on acute promyelocytic leukemia and endothelial cells are differently regulated by retinoic acid, arsenic trioxide and chemotherapeutic agents.

The aberrant expression of tissue factor (TF) in acute promyelocytic leukemia (APL) cells has been implicated in the pathogenesis of the APL coagulopathy. In this study, we found that in APL patients receiving ATRA or As2O3 treatment, the improvement in hypercoagulobility and hyperfibrinolysis paralleled the correction of plasma fibrinogen level and amelioration of bleeding symptoms. Notably, clinical improvement was also correlated to ATRA/As2O3-induced rapid decrease of membrane procoagulant activity (PCA) and TF contents of APL blasts. Consistent with the in vivo findings, the membrane PCA, TF antigen and its mRNA level within NB4 cells were rapidly down-regulated by 1 microM ATRA or As2O3, while 0.2 microg/ml DNR increased these TF parameters prior to its effect upon apoptosis induction. The down-regulation of TF mRNA by ATRA was partially de novo protein synthesis-dependent and at least partially attributed to a mechanism of destabilizing TF mRNA. On the other hand, in addition to its modulation on mRNA, As2O3 could also induce an accelerated TF protein turnover. These distinct effects were corroborated with the properties of these agents in causing the degradation of PML-RARalpha protein. All three therapeutic agents, however, enhanced the potential of NB4 cells to stimulate the expression of TF and PCA in endothelium. Taken together, our data suggest that the rapid and distinct regulation of TF on APL cells by these therapeutic agents might at least partially contribute to their effects on APL coagulopathy.

Adolescent↗

PubMed1999

TGF-beta1 expression is reduced in hydrocephalic H-Tx rat brain.

Transforming growth factor-beta1 (TGF-beta1) is a cytokine with diverse biological effects. Overexpression of TGF-beta1 in mice has been shown to induce progressive hydrocephalus. We have used a quantitative RT-PCR method to analyze the TGF-beta1 expression in the brains of H-Tx rat, a model of congenital hydrocephalus. Our studies have shown that rather than increased expression, the 3- and 10-day hydrocephalic H-Tx rats have significantly lower TGF-beta1 levels than their normal siblings (p < 0.01). This difference became insignificant in the 21-day group. Besides, both hydrocephalic and normal H-Tx rats have significantly lower TGF-beta1 levels in all three age groups of 3-, 10- and 21-days than SD control rats (p < 0.01 in all three groups) although the difference tends to become less significant with development. We also tested the expression of another cytokine, the epidermal growth factor, and observed a similar reduction. This suggests that the TGF-beta1 expression change is not unique to the development of hydrocephalus in this rat model. Our hypothesis is that the TGF-beta1 expression decrease in the H-Tx rat is not the cause of the disease. Rather it might be the result of feedback inhibition by increase in the expression of the gene it regulates, including an extracellular matrix component. Effort is currently being made to test this hypothesis.

Age Factors↗

PubMed1999

Physicochemical consequences of amino acid variations that contribute to fibril formation by immunoglobulin light chains.

The most common form of systemic amyloidosis originates from antibody light chains. The large number of amino acid variations that distinguish amyloidogenic from nonamyloidogenic light chain proteins has impeded our understanding of the structural basis of light-chain fibril formation. Moreover, even among the subset of human light chains that are amyloidogenic, many primary structure differences are found. We compared the thermodynamic stabilities of two recombinant kappa4 light-chain variable domains (V(L)s) derived from amyloidogenic light chains with a V(L) from a benign light chain. The amyloidogenic V(L)s were significantly less stable than the benign V(L). Furthermore, only the amyloidogenic V(L)s formed fibrils under native conditions in an in vitro fibril formation assay. We used site-directed mutagenesis to examine the consequences of individual amino acid substitutions found in the amyloidogenic V(L)s on stability and fibril formation capability. Both stabilizing and destabilizing mutations were found; however, only destabilizing mutations induced fibril formation in vitro. We found that fibril formation by the benign V(L) could be induced by low concentrations of a denaturant. This indicates that there are no structural or sequence-specific features of the benign V(L) that are incompatible with fibril formation, other than its greater stability. These studies demonstrate that the V(L) beta-domain structure is vulnerable to destabilizing mutations at a number of sites, including complementarity determining regions (CDRs), and that loss of variable domain stability is a major driving force in fibril formation.

Amino Acid Sequence↗

PubMed1999

Social interactions of high school students with mental retardation and their general education peers.

The informal social interaction behavior that is typical of a high school lunchroom in which general and special education students are physically included was described. Using systematic observation and social comparison methods, we compared the performance of two groups of students (12 general education students and 12 students with mental retardation). Both similarities and differences were found in the interactions of students with mental retardation and their general education peers with respect to social behaviors, conversational topics, and context within which interactions occurred. However, despite being in proximity, students with mental retardation rarely interacted with any of approximately 500 general education students present in the lunchroom. Implications are discussed for increasing social interaction among high school students.

Adolescent↗

PubMed1999

[Cloning the 5 ' end fragment of ST13 cDNA by nested PCR].

OBJECTIVE: To clone and sequence the 5' -end fragment of ST13 cDNA. METHODS: The 5' -end fragment of the ST13cDNA was amplified directly from cDNA library by nested PCR method, and cloned into pGEM-T. easy vector, then the sequencing of the inserted PCR product was performed. RESULTS: After primary and secondary PCR, two PCR products obtained with the size of about 550bp and 480bp, respectively, were both proved to be the 5' -end of ST13 cDNA by sequencing. CONCLUSION: the method presented is very simple and effective for cloning and sequencing the 5'-end of a target gene.

Cloning, Molecular↗

PubMed1999

Cloning of Schistosoma japonicum Chinese strain 22.6kD membrane-associated protein (Sj-22.6) gene and its overproduction on Escherichia coli.

A 567bp DNA fragment was amplified from Schistosoma japonicum adult worm mRNA by RT-PCR. Sequence analysis revealed that this fragment contained S. Japonicum Chinese strain membrane-associated protein (Sj-22.6) gene. Then this gene was cloned into the expression vector pGEX-4T, and subsequently expressed in Escherichia coli. The recombinant GST-fusion protein was purified by glutathione agarose affinity chromatography. Its molecular weight was about 48 kD. The yield of expression was around 40 mg/L E.coli culture. The immunological test suggested that the recombinant protein had good antigenity which could make a good basis for the research of its immunological function in Schistosomiasis.

Animals↗

PubMed1999

Cost of medications for elderly in a nursing home.

The rising cost of medical care, particularly for elderly patients in nursing homes, is receiving increasing attention. The purpose of this study was to investigate the cost of and the average number of medications taken per patient in a nursing home. The study included 116 residents of a nursing home in New Orleans, Louisiana. Relevant information about the number of medications taken by each patient on a regular basis was obtained by chart review. The cost of medications was calculated from the Red Book (which represents the cost of drugs to the pharmacy), because the medication prices charged by the nursing home were not available. The number of medications used per patient per day expressed as mean +/- S.D. was 8.1 +/- 4.1. The cost of medications per patient per month expressed as mean +/- S.D. was $182 +/- 141. The estimated annual cost of medications per patient was $2,184. It is highly likely that the cost to the patient is higher than the cost shown here. This preliminary study shows that elderly patients take several medications associated with significant expense.

Aged↗

PubMed1999

[The mechanisms of arsenic trioxide-induced apoptosis in hematopoietic malignant cells].

OBJECTIVE: To understand if arsenic trioxide (As2O3) is related to the alteration of mitochondrial transmembrane potentials (delta psi m) and its possible mechanisms. METHODS: Acute promyelocytic leukemia (APL) cell line NB4, chronic lymphoblastic leukemia (CLL) cell line SKW-3, Burkitt's lymphoma cell line Namalwa and other acute myeloid leukemia cell lines HL-60 and U937 were used as in vitro models. The delta psi m was detected by the double staining of propidium iodide (PI) and Rhodamine 123(Rh123), while apoptosis was confirmed by cell viability, sub-G1 cell content as well as gel electrophoresis of genomic DNA and morphological observation. In addition, cellular content of malondialdehyde (MDA) was detected. RESULTS: In the cells sensitive to As2O3-induced apoptosis, the delta psi m was disrupted with As2O3 treatment. The disulfide-bond reducing agent dithiothreitol (DTT) significantly blocked As2O3-induced delta psi m collapse and apoptosis. For example, with 1 mumol/L As2O3 treatment for 48 hours, PI- Rh123- cells was increased to (16.0 +/- 2.5)%, and DTT simultaneous treatment reduced PI- Rh123- cells and apoptotic cells to (2.9 +/- 0.2)%, and (1.8 +/- 0.3)%, respectively. On the other hand, As2O3 also significantly induced MDA production in NB4(0.479 +/- 0.044, P < 0.01) and SKW-3 (0.168 +/- 0.018) nmol/L, P < 0.01) cells, whereas the effect could not be blocked by DTT. CONCLUSIONS: The disruption of the delta psi m is the key event of As2O3-induced apoptosis, and the essential mechanisms may be related to the oxidation of thiols; the reactive oxygen species are involved with apoptosis induced by As2O3, but they are not the main points.

Apoptosis↗

PubMed1999

Dose-effect of dietary L-arginine supplementation on burn wound healing in rats.

OBJECTIVE: To investigate the dose-effect of dietary L-arginine supplementation on burn wound healing in rats. METHODS: 218 Sprague-Dawley rats (weighing 200-250 g) were subjected to 10% deep partial thickness scald burns and were randomized into six groups. Groups A, B, C, D, E and F received 800, 400, 200, 100, 50 and 0 mg.kg-1.d-1 L-arginine in the form of L-arginine solution, and 0, 727, 1090, 1272, 1364, and 1454 mg.kg-1.d-1 glycine, respectively. Each solution was isonitrogenous. The times of completing re-epithelization were recorded. The contents of hydroxyproline (OHP) in burn wound area (index of reparative collagen synthesis) and the ratios of type I and type III collagen were examined in all groups. RESULTS: The times of completing re-epithelization (day) in groups A, B, C, D, E, and F were 24.9 +/- 1.95, 22.5 +/- 2.0, 20.2 +/- 2.4, 23.5 +/- 2.6, 23.8 +/- 3.5, and 24.7 +/- 2.3, respectively. The contents of hydroxyproline in groups B, C and D were higher than in groups A, E and F on PBD 7, 10 and 14. The ratios of type I and type III collagen in groups B, C and D were lower than in groups A, E and F. CONCLUSION: Oral dietary L-arginine supplementation from 100 mg.kg-1.d-1 to 400 mg.kg-1.d-1 shortened the times of re-epithelization, increased amounts of hydroxyproline, and accelerated the synthesis of reparative collagen in burn rats.

Animals↗

PubMed1999

[Glutathione synthesis inhibitor enhances arsenic trioxide-induced apoptosis].

OBJECTIVE: To illustrate the possible role of thiols (SH-groups) in arsenic trioxide (As2O3)-induced apoptosis. METHODS: Leukemia (NB4, HL60, U937) and lymphoma (Jurkat and Namalwa) cell lines were treated with As2O3 together with buthionine sulfoximine (BSO), a selective inhibitor of gamma-glutamylcysteine synthetase. The mitochondrial transmembrane potentials (delta psi m) and the percentage of cells in apoptosis were measured by means of flow cytometry. RESULTS: One mmol/L BSO significantly enhanced As2O3-induced delta psi m collapse and apoptosis in NB4 cells. One mumol/L As2O3 did not induce the delta psi m collapse and apoptosis in Namalwa, HL60, U937 and Jurkat cells, while these effects were induced significantly by the co-treatment of 1 mumol/L As2O3 and 1 mmol/L BSO. CONCLUSION: Thiols are important chemosensors of As2O3-induced delta psi m collapse and apoptosis.

Apoptosis↗

PubMed1999

[Effect of ATP on malignant phenotype of a human gastric cancer cell line].

OBJECTIVE: To study the effect of ATP on proliferation and differentiation of a human gastric cancer cell line. METHODS: M17, a subclone of human gastric cancer cell line MGC-803, was treated in vitro with ATP(0.23 mg/ml). After 48 hr, the following parameters were examined. (1) Proliferation of cells by daily cell counting. (2) Microvilli of the cells were observed by scanning EM. (3) Gap junction intercellular communication was examined by mechanical scraping and Lucifer dye transfer. (4) Microfilament of the cytoskeleton was studied with fluorescin-labeled phalloidin. (5) Vinculin adhesion plague was stained immunocytochemically with monoclonal antibodies. RESULTS: ATP significantly inhibited the in vitro growth of M17 cells. The ATP-treated M17 cells showed disappearance of microvilli on the cell surface, increased gap junction intercellular communication, improved organization of microfilament bundles and reappearance of vinculin adhesion plagues. CONCLUSION: ATP not only inhibits proliferation but also induces differentiation of a human gastric cancer cell line with reversion from malignant toward normal phenotype. The parameters examined could serve as useful biomarkers of human gastric cancer.

Actin Cytoskeleton↗

PubMed1999

[Study of microsatellite instability of colotectal cancer and its clinical significance].

OBJECTIVE: To evaluate microsatellite instability (MI) of colorectal cancer in China. METHOD: Replication error (RER) status was examined by using 6 microsatellite loci D2S123, D2S119, D13S160, D8S282, D3S1293 and D18S58. The loci were amplified by PCR technique. The PCR products were separated on denatured polyacrylamide gel and then silver stained. RESULTS: Of the 60 cases of colorectal cancer studied, 20 (33.3%) showed MI, 11 cases (18.3%) were RER positive. In 11 RER-positive cases, 4(36.4%) had family history of malignant tumor, while only 8.2% had positive family history in RER-negative cases (P < 0.05). The RER-positive patients were younger, and their cancer occurred more frequently in the colon with invasive type of growth. There were more cancers in Dukes III and IV in the REF-positive patients. In 5 colorectal cancer cases associated with adenoma, MI was detectable in 4 adenomas. CONCLUSION: MI phenotype might be present ubiquitously in sporadic colorectal cancers in China. Its frequency is comparable to that of other reports. MI is a relatively early molecular event in the genesis of colorectal cancers. RER is a useful sign of susceptibility to the development of colorectal cancer.

Adult↗

PubMed1999

[Resection of caudate lobe of liver: report of 26 cases].

OBJECTIVE: To summarize the experience in caudate lobectomy for 26 cases. METHODS: Caudate lobectomy was performed in 26 cases by Peng's multifunctional operative dissector (PMOD) to transect the liver parenchyma (Curettage and Aspiration technique). Primary liver cancer was noted in 18 cases, hilar cholangiocarcinoma in 4, gallbladder carcinoma in 1, right adrenocortical adenocarcinoma in 1, hepatoangioma in 1 and hepatoangiosarcoma in 1. Five cases underwent isolated caudate lobectomy, 1 combined caudate lobectomy with right trisegmentectomy, 6 combined caudate lobectomy with right hemihepatectomy, 9 combined caudate lobectomy with left hemihepatectomy, and 5 combined caudate lobectomy with segmentectomy. RESULTS: The operations were carried out successfully. Follow up for 2 - 23 months, 1 case died from pulmonary infraction 2 weeks after operation, 1 died from lung metastasis 2 months after operation, 10 died from tumor recurrence or metastasis 3, 11, 12, 15, 15, 15, 15, 19, 30, 30 months after operation respectively. The other 14 cases are still alive for 2 to 18 months. CONCLUSIONS: With PMOD, it is possible to dissect the structure precisely. Therefore the caudate lobe can be isolated from the three porta hepatis without much difficulty. Caudectomy can be performed safely.

Adult↗