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Biomedical subjects

H Xue

Publications and source records attributed to H Xue.

At least 91 records · Page 5Linked to original sources
PubMed1997

[Quantitative determination of 7-ketocholesterol in human fetal liver cell supernatant and lysate by high performance liquid chromatography].

7-Ketocholesterol (7-KC), which is a major oxidation product of cholesterol and is selective cytotoxic to tumour cells, was isolated from human fetal liver. A fast, sensitive method of high performance liquid chromatography for the quantitation of 7-KC has been developed and applied to the determination of 7-KC in human fetal liver cell suspension. In this procedure a mixture of 2 : 1 chloroform-methanol (V/V) was used as extraction solvent. The extract was washed with distilled water and then evaporated to dryness under N2. An adsorption liquid chromatographic system used included mu-Porasil SiO2 column, hexane : iso-propanol (91 : 9) mobile phase and UV detector at 233nm. It was found that the level of 7-KC in human fetal liver cell supernatant was higher than in liver lysate.

Chromatography, High Pressure Liquid↗
PubMed1997

Analysis of clonality of lymphocytic leukemia and lymphoma by T-cell receptor gene rearrangement.

OBJECTIVE: To analyse the relationship between the number of T-cell receptor (TCR) gamma gene rearrangement and clonality of malignant cells in lymphocytic leukemia and lymphoma. METHODS: The TCR gamma gene characteristics of 73 cases of lymphocytic leukemia and lymphoma and other diseases that had presented 1 or 2 prominent bands of amplified TCR gamma VI subgroups-J1/2 gene rearrangement (GR) were detected by polymerase chain reaction-restriction enzymes (PCR-RE), heteroduplex formation (HDF), DNA sequencing and single-strand conformational polymorphism (SSCP). RESULTS: Thirty-four percent patients had 2 of TCR gamma GR (biallelic rearrangement); twenty-six percent had 1 of TCR gamma GR; fifty-four percent of acute lymphocytic leukemia's and nineteen percent of non-Hodgkin's lymphomas (NHL) had 2 of TCR gamma GR. HDF could rapidly confirm more than 1 of alleles while more alleles were difficult to be recognized by restriction analysis. Sense and antisense strands of heteroduplex were composed of 2 of TCR gamma GR respectively. By combining HDF method, oligoclonalities in three patients (2 acute lympholytic leukemia and 1 myelodysplastil syndrome and clone evolution in one NHL were found. CONCLUSIONS: The fact that many patients had 2 of TCR GR means that complications of two neoplastic clones can be affirmed only if more than 2 of TCR GR are found. HDF can be used to detect the clonality, oligoclonality and polyclonality of lymphoid cells in lymphocytic leukemia and lymphoma by analysis of the difference of gene segments. HDF is a reliable method for the clone evolution research of lymphoid malignancies in progression.

Base Sequence↗
PubMed1996

A concerted tryptophanyl-adenylate-dependent conformational change in Bacillus subtilis tryptophanyl-tRNA synthetase revealed by the fluorescence of Trp92.

A semi-conserved tryptophan residue of Bacillus subtilis tryptophanyl-tRNA synthetase (TrpRS) was previously asserted to be an essential residue and directly involved in tRNATrp binding and recognition. The crystal structure of the Bacillus stearothermophilus TrpRS tryptophanyl-5'-adenylate complex (Trp-AMP) shows that the corresponding Trp91 is buried and in the dimer interface, contrary to the expectations of the earlier assertation. Here we examine the role of this semi-conserved tryptophan residue using fluorescence spectroscopy. B. subtilis TrpRS has a single tryptophan residue, Trp92. 4-Fluorotryptophan (4FW) is used as a non-fluorescent substrate analog, allowing characterization of Trp92 fluorescence in the 4-fluorotryptophanyl-5'-adenylate (4FW-AMP) TrpRS complex. Complexation causes the Trp92 fluorescence to become quenched by 70%. Titrations, forming this complex under irreversible conditions, show that this quenching is essentially complete after half of the sites are filled. This indicates that a substrate-dependent mechanism exists for the inter-subunit communication of conformational changes. Trp92 fluorescence is not efficiently quenched by small solutes in either the apo- or complexed form. From this we conclude that this tryptophan residue is not solvent exposed and that binding of the Trp92 to tRNATrp is unlikely. Time-resolved fluorescence indicates conformational heterogeneity of B. subtilis Trp92 with the fluorescence decay being best described by three discrete exponential decay times. The decay-associated spectra (DAS) of the apo- and complexed-TrpRS show large variations of the concentration of individual fluorescence decay components. Based on recent correlations of these data with changes in the local secondary structure of the backbone containing the fluorescent tryptophan residue, we conclude that changes observed in Trp92 time-resolved fluorescence originate primarily from large perturbations of its local secondary structure. The quenching of Trp92 in the 4FW-AMP complex is best explained by the crystal structure conformation, in which the tryptophan residue is found in an alpha-helix. The amino acid residue cysteine is observed clearly within the quenching radius (3.6 angstroms) of the conserved tryptophan residue. These tryptophan and cysteine residues are neighbors, one helical turn apart. If this local alpha-helix was disrupted in the apo-TrpRS, this disruption would concomitantly relieve the putative cysteine quenching by separating the two residues. Hence we propose a substrate-dependent local helix-coil transition to explain both the observed time-resolved and steady-state fluorescence of Trp92. A mechanism can be further inferred for the inter-subunit communication involving the substrate ligand Asp132 and a small alpha-helix bridging the substrate tryptophan residue and the conserved tryptophan residue of the opposite subunit. This putative mechanism is also consistent with the observed pH dependence of TrpRS crystal growth and substrate binding. We observe that the mechanism of TrpRS has a dynamic component, and contend that conformational dynamics of aminoacyl-tRNA synthetases must be considered as part of the molecular basis for the recognition of cognate tRNA.

Adenosine Monophosphate↗
PubMed1996

Farnesyl analogues inhibit vasoconstriction in animal and human arteries.

Recent studies have suggested that nonsterol, mevalonate-derived metabolites are implicated in the control of vascular tone and blood pressure. Because of the metabolic importance of farnesyl pyrophosphate, a 15-carbon (C15) intermediate of the cholesterol pathway, the vasoactive properties of the farnesyl motif were investigated. Two farnesyl analogues were used: farnesol, the natural dephosphorylated form of farnesyl pyrophosphate, and N-acetyl-S-trans,trans-farnesyl-L-cysteine (AFC), a synthetic mimic of the carboxyl terminus of farnesylated proteins. Both compounds inhibited NE-induced vasoconstriction in rat aortic rings at micromolar concentration. Their action was rapid, dose dependent, and reversible. Shorter (C10) and longer (C20) isoprenols as well as N-acetyl-S-geranyl-L-cysteine (C10) did not inhibit the response to NE. In contrast, N-acetyl-S-geranylgeranyl-L-cysteine (C20), exhibited vasoactive properties similar to AFC. It was further demonstrated that AFC and farnesol inhibited KCl and NaF-induced contractions, suggesting a complex action on Ca2+ channels and G protein-dependent pathways. Finally, the effect of farnesol and AFC on the NE response was reproduced in human resistance arteries. In conclusion, mevalonate-derived farnesyl analogues are potent inhibitors of vasoconstriction. The study suggests that farnesyl cellular availability is an important determinant of vascular tone in animals and humans, and provides a basis for exploring farnesyl metabolism in humans with compromised vascular function as well as for using farnesyl analogues as regulators of arterial tone in vivo.

Animals↗
PubMed1996

Immunogenicity and relative attenuation of different vaccinia-rabies virus recombinants.

Immunogenicity and relative attenuation were examined for the following Tian Tan strain vaccinia-rabies recombinant viruses: 1) NGc-1, which coexpresses the glycoprotein (G) and nucleocapsid protein (N) of the rabies virus Challenge Virus Standard (CVS) strain; 2) Nc-1, which expresses the CVS N; 3) Gc-2, Gc-3, Gc-4, and Gc-5, which express CVS G via promoters from different vaccinia strains or from different vaccinia genome loci; 4) Ga-1, which expresses the G of rabies virus strain aG; and 5) Gas-1; which expresses the carboxyltruncated G ectodomain (Gs) of strain aG. All but Nc-1 and Gas-1 induced rabies virus neutralizing antibodies (VNAs) and protected groups of mice at very high frequencies from intramuscular (IM) or intracranial (IC) challenge with CVS or SW1 Shanghai dog street rabies virus (SRV); Nc-1 and Gas-1 were partly protective, more frequently against IM challenge. NGc-1 and Gc-5 appeared to induce high levels of VNAs sooner after immunization than the other constructs in mice. Relative attenuation assessed by IM infection of neonatal mice, IC infection of adult mice, and intradermal infection of rabbits with varying doses was best for NGc-1. All the recombinants were at least 100-fold more attenuated than the parent, Tian Tan vaccinia virus. Gc-2, Gc-3, Gc-4, Gc-5, and NGc-1 induced VNAs after immunization of dogs, and a subset of VNA-positive animals vaccinated with NGc-1 or Gc-3 were protected against an otherwise lethal IM injection of SRV at 21 days after vaccination.

Animals↗
PubMed1996

Dibutyl phthalate purged autologous bone marrow transplant in the treatment of leukemia.

It has been proved that di-N-butyl phthalate (DBP) is singular in killing leukemic cells selectively or accelerating the deterioration of residual leukemic cells in long-term marrow culture in vitro. Based on this principle, the DBP-purged autologous bone marrow transplant has been applied to the treatment of a group of 14 patients suffering from acute nonlymphocytic leukemia. After 5-10 days of in vitro co-culture of marrow cells with DBP at a concentration of 50 micrograms/ml, the recovery of total nucleated cells and the amount of CFU-GM were 67.5% and 68.1%, respectively. In all patients, the reconstitution of hematopoiesis was observed after pre-conditioning and transfusion of purged marrow cells. Among these, two patients had a relapse, two patients died from complications of transplant, one patient died from non-leukemic disease, and the others are all alive and free of disease; the mean survival time as calculated recently was 15 months. These preliminary clinical data support that marrow culture in the presence of DBP is a safe and effective measure for treating leukemia in purged autologous bone marrow transplant.

Adolescent↗
PubMed1996

Intratracheal pulmonary ventilation provides effective ventilation in a near-drowning model.

Overdistension of the lungs from high inspiratory pressure is increasingly recognized as a major contributor to lung injury and worsening respiratory failure in the child who requires prolonged mechanical ventilation. Many modes of ventilation (such as high-frequency ventilation) have been introduced in an attempt to decrease this lung injury. Recently, a new mode of tracheal ventilation, intratracheal pulmonary ventilation (ITPV), has been described. By using a catheter positioned at the carina with continuous gas flow, it is possible to achieve effective ventilation at very low pressures. The purpose of this study was to evaluate the usefulness of ITPV in a near-drowning model. Ten domestic Yorkshire swine underwent arterial, venous, and pulmonary arterial catheter as well as tracheotomy placement. All animals received 13 mL/kg of fresh water intratracheally to induce a pulmonary injury. Six pigs were ventilated for 4 hours using ITPV; the other four pigs received conventional mechanical ventilation (CMV). Circulatory and ventilatory pressures, hemodynamic variables, arterial blood gases, and end-tidal CO2 were measured before lung injury and every 30 minutes thereafter. Both proximal and distal peak and mean airway pressures were measured. The animals were ventilated as needed to maintain the arterial blood gases in the normal range. The authors found the expected changes in pulmonary compliance, oxygen requirement, and airway pressure after inducement of lung injury. The six animals treated with ITPV had significantly lower airway pressures than those of controls. Peak inspiratory pressures with ITPV were 8.2 +/- 1.9 cm H2O versus 17.8 +/- 3.7 with CMV (P < .001). Distal mean airway pressures using ITPV were 2.3 +/- 0.1 cm H2O versus 9.0 +/- 3.2 with CMV (P < .01). With respect to hemodynamic variables, there were no differences between experimental and control animals. In conclusion, ITPV can afford effective ventilation in a near-drowning model of lung injury at airway pressures significantly lower than those required with CMV. ITPV could be a very valuable addition to the currently available methods of mechanical ventilation.

Animals↗
PubMed1996

[Expression of protooncogene bcl-2 in thyroid tumors].

OBJECTIVE: To determine the expression of protooncogene bcl-2 in thyroid tumors and its relationship to the development and prognosis of the tumor. METHODS: 124 cases of thyroid tissues (41 thyroid carcinomas, 53 thyroid adenomas, 20 thyroid tissues adjacent to cancer and 10 normal thyroid tissues) were immunohistochemically stained for bcl-2, by using bcl-2 protein monoclonal antibody. The positive-staining rates in different thyroid tissues were compared statistically. RESULTS: Bcl-2 immunoreactivity was found in thyroid carcinomas (43.9%), thyroid adenomas (22.6%), and thyroid tissues adjacent to cancer (15.0%). The positive-staining rate in thyroid carcinomas was higher than that in thyroid adenomas (P = 0.0439) and that in thyroid tissues adjacent to cancer (P = 0.0430). In thyroid carcinoma, the higher positive-staining rates were found in the cases of undifferentiated carcinoma and follicular carcinoma, as well as in the cases of positive lymph nodes or at tumor stage II and IV. CONCLUSION: The results suggest that the over-expression of bcl-2, a possible prognostic marker of thyroid cancer, may be related to the development of thyroid tumor.

Adenoma↗
PubMed1996

[Results on Ivor-Lewis esophagogastrectomy for 338 cases of carcinoma of esophagus].

Three hundred thirty eight patients with carcinoma in the middle and lower thirds of the esophagus received Ivor-Lewis esophagogastrectomy (separate laparotomy and right thoracotomy incisions) from February 1986 to June 1992. The total resectability was 95.2%. Lymph node metastases were found in 136 cases (40.2%). Postoperative complications developed in 10.3% of the patients. No anastomotic leakage, nor postoperative (within 30 days) death and hospital death occurred. Major pulmonary complications occurred in 28.6% of the patients. The overall 1-, 3- and 5-year survival rate was 88.5% (231/261), 63.1% (125/198) and 48.4% (60/124), respectively. The five-year survival rate was 64.1% (41/64) in patients with negative lymph nodes as compared to 31.7% (19/60) with positive nodes. The superiority of this technique was a significant improvement of the 5-year survival rate. This was due to better exposure of the operation field which made thorough dissection of lymph nodes possible, especially those along the right recurrent laryngeal nerve. Better operative exposure also provided chances for redical resection with less interference from the aortic arch. It made anastomosis easier to perform so that stenosis and leakage were less likely to occur. Ivor-Lewis esophagogastrectomy is a superior surgical procedure of choice for the treatment of cancer at the lower and middle thirds of the esophagus.

Adult↗
PubMed1995

Interferon induction of human tryptophanyl-tRNA synthetase safeguards the synthesis of tryptophan-rich immune-system proteins: a hypothesis.

Ever since the discovery that the human tryptophanyl-tRNA synthetase (TrpRS)-encoding gene is induced by interferon (IFN) [J. Fleckner et al., Proc. Natl. Acad. Sci. USA 88 (1991) 11520-11524] and contains IFN-response regulatory elements [Frolova et al., Gene 128 (1993) 237-245], the biological rationale for this induction has remained unresolved. A survey of immune system proteins in this study reveals that the human major histocompatibility complex (MHC) antigens, beta-2-microglobulin (beta MG) and complement factor B, which are known to be induced by IFN, together with immunoglobulins (Ig) are all exceptionally enriched in Trp residues, as compared to human proteins in general. It also reveals the conservation of a sequence motif, CX10-17 WX26-62C, in Ig domains. The conservation of this sequence motif and the utility of Trp residues within antigen-binding sites clearly contribute to the Trp enrichment in Ig. These observations suggest a biological rationale for the induction of TrpRS by IFN in safeguarding Trp incorporation for the IFN-enhanced synthesis of immunological molecules.

Amino Acid Sequence↗
PubMed1995

Iodine-mediated inactivation of lipid- and nonlipid-enveloped viruses in human antithrombin III concentrate.

Human plasma-derived protein concentrates intended for clinical use must be treated for viral inactivation to ensure patient safety. This study explored the use of liquid iodine for inactivation of several lipid- and nonlipid-enveloped viruses in an antithrombin III (AT-III) concentrate. Iodine at levels of 0.01% to 0.02% caused between 43% and 94% loss of AT-III activity, as well as degradation of AT-III as shown by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blot analysis. However, addition of up to 0.1% human albumin protected the AT-III against both inactivation and fragmentation. At albumin levels sufficient to retain greater than 75% of AT-III activity, greater than 6 logs of sindbis, encephalomyocarditis, and vesicular stomatitis viruses, greater than 4 logs of pseudorabies, and greater than 3 logs of human immunodeficiency virus were inactivated. Except with sindbis virus, this represented complete inactivation of all the viruses spiked into the AT-III concentrate.

Animals↗
PubMed1995

Malignant solid tumors in neonates: a 40-year review.

To evaluate the outcome of neonatal malignant solid tumors, we reviewed the records of 222 infants under the age of 1 year with malignant disease who were treated at the University of Texas M.D. Anderson Cancer Center over a 40-year period. Forty-five cases of neonatal (< 30 days old at the time of presentation) malignancies were found. Thirty-two infants had solid tumors and form the basis of this report. Diagnoses included soft tissue sarcoma (13), brain tumor (5), neuroblastoma (6), retinoblastoma (3), malignant melanoma (2), hemangiopericytoma (2), and nephroblastoma (1). The mean age at which initial signs and symptoms were noted was 9 days of life. Fifty-nine percent (19) presented within the first week of life, and 47% (15) presented at birth. The mean age at histological diagnosis was 54 days. The head and neck region was the most common site (18), followed by trunk (9), and extremities (5). Thirty-one patients underwent surgical resection of the primary tumor. Thirteen of those neonates received no additional chemotherapy and/or radiation therapy, whereas 18 received some combination of surgery plus perioperative chemotherapy and/or radiation therapy. Overall survival was 78% (25 of 32) with an average follow-up of 8 years (range, 2 months to 29 years). There were no survivors among those patients with distant metastatic disease at the time of diagnosis. Despite delays, prognosis is excellent in the absence of distant metastatic disease, particularly for extracranial tumors.

Brain Neoplasms↗
PubMed1995

Mevalonate availability affects human and rat resistance vessel function.

Previous data in rat conductance vessels indicated that cellular mevalonate contributes to vascular tone and systemic blood pressure control. Using exogenous mevalonate (M) or lovastatin, a 3-hydroxy-3-methyl-glutaryl CoA (HMG-CoA) reductase inhibitor (L), we characterized the role of mevalonate availability in resistance artery function, both in experimental animals and humans. Rat mesenteric artery resistance vessels (MARV, n = 9) were incubated for 48 h with either L, M, L + M, or vehicle (V) and tested for reactivity to NE, serotonin, acetylcholine, atrial natriuretic peptide, and sodium nitroprusside (SNP). Lovastatin increased sensitivity to NE (P < 0.03) and serotonin (P < 0.003), and significantly impaired the response to all three vasodilators. These effects were reversed by co-incubation with mevalonate. Mevalonate alone had no effect. In separate experiments, intravascular free Ca2+ concentration (ivfCa2+) was determined in fura-2AM loaded MARV. Basal ivfCa2+ was increased after a 48-h exposure to L (52.7 +/- 4.6 nM, L, vs. 29.7 +/- 2.4 nM, V, n = 12, P < 0.003), as were ivfCa2+ levels following stimulation with low (100 nM) NE concentrations. Similar ivfCa2+ concentrations were achieved during maximum contraction with NE (10 mM) in both groups. Human resistance arteries of human adipose tissue were also studied. Lovastatin increased the sensitivity to NE (ED50 = 372 +/- 56 nM, V, and 99 +/- 33 nM, L, P < 0.001) and significantly decreased the relaxation to acetylcholine and SNP of human vessels. We conclude that mevalonate availability directly contribute to resistance vessel function and vascular signal transduction systems in both experimental animals and humans. The study calls for the identification of non-sterol, mevalonate-derived vasoactive metabolites, and suggests that disorders of the mevalonate pathway can alter vascular tone and cause hypertension.

Adult↗
PubMed1995

[Observation on antibody levels of rabbits infected with single sex cercariae of Schistosoma japonicum].

Nine rabbits infected with male S. japonicum cercariae (worm recovery 15-133, mean 53.1) and 9 rabbits infected with female cercariae (worm recovery 1-102, mean 36.1) were bled periodically until 1 year post-infection. The sera were tested by ELISA, LA and CHR for antibody detection. Results showed that the positive rates were 88.9%, 55.6% and 83.3%, respectively. The duration of positive reaction was 3-51 wk post-infection for ELISA, 4-17 wk for LA and 2-35 wk for CHR and the fluctuated results were obtained in ELISA while positive CHR and LA results usually remained stable. The above-mentioned results suggest that antibody detection methods should not be neglected due to its sensitivity although antigen detection methods are considered more favorable. For the surveillance of schistosomiasis in endemic areas where schistosomiasis is under control, antibody detection methods are still worthy of recommending for case finding of new infections.

Animals↗
PubMed1995

[The clonal origin of multiple myeloma].

In order to explore the clonal origin and malignant pathway of multiple myeloma (MM), a study has been made to investigate the differentiation stage of malignant progenitor cells in peripheral blood (PB) of MM. The immnophenotype of mononuclear cells (MC) in PB and bone marrow (BM) from 17 patients with MM were studied with APAAP method by using monoclonal antibodies directed to a series of B-cell markers (CD10, CD19, CD20, CD45RA, CD45RO, CD38). There were no plasma cells in samples of PB examined. Out of the 17 patients, MC of PB from 10 expressed plasma cell antigen CD38. This expression was significantly different from normal control (P < 0.001) and identical with that of BM. MC of 9 patients were CD38+ and CD45RO+, 3 were CD38+, CD45RO+ and CD45RA+ and 1 was CD38+, CD45RA+, CD45RO+ and CD10+ in PB. The results indicate that while the B-cell marker's expression of PB matches with that of BM, its forms are diversified. This suggests that the PB of MM patients contains precursors at multiple differentiation stages of myeloma cells, from early B cell to active B cell, late B cell and preplasma cell. MC of PB from 10 patients expressed CD45RO while that of BM from 5 out of them expressed the same. This indicates that preplasma cells which are CD45RO+ in PB may eventually return to BM for homing and differentiating into plasma cells, thus losing CD45RO and expressing CD38 only. This study has proved the presence of malignant cells in PB of MM, confirmed the speculation of the malignant pattern and provided the theoretical basis for purging of PB in autologous peripheral blood stem cell transplantation.

Adult↗
PubMed1994

Iodine 131 thyroid ablation in female children and adolescents: long-term risk of infertility and birth defects.

BACKGROUND: The use of radioactive iodine, or iodine 131 (131I), for remnant thyroid ablation and the treatment of cervical and distant metastatic disease in patients with thyroid cancer is well accepted. 131I concentrates in the bladder, and irradiation to the ovaries has been theorized to increase the risk of infertility and birth defects in subsequent offspring. METHODS: We conducted a retrospective review of the charts of 154 children and adolescents treated at our institution for thyroid cancer between 1951 and 1991. Review of these charts identified 68 females diagnosed with thyroid cancer, < or = 20 years of age, who received 131I as part of their therapy at our institution. Charts were reviewed and patients recontacted, and initial tumor, date of diagnosis, and 131I administration, including doses, were recorded. Complete pregnancy histories including current health status of the children were also recorded. RESULTS: Twenty-two patients who never attempted pregnancy were excluded from analysis. Eleven patients could not be contacted and were considered lost to follow-up and thus excluded from the study. In the remaining 35 patients, mean age at 131I administration was 18.3 years (range 14.1-20.8), mean follow-up, 16.8 years (range 5.6-39.8), and mean 131I dose, 148.53 mCi (range 77.2-250). Three patients were diagnosed infertile after extensive workup (8.6%). The remaining 32 patients had 69 pregnancies resulting in 60 term and four premature deliveries. There were two elective abortions for nonmedical reasons and three spontaneous abortions. Only two children were conceived within 1 year of 131I therapy. Both were born with birth defects that proved fatal within 8 months. No other children were born with birth defects. One other child born with an estimated gestational age of 27 weeks died due to complications related to his prematurity. No anomalies were noted at autopsy. Of the 61 children alive for follow-up, no major health problems were identified other than asthma in two children. CONCLUSIONS: 131I, used in doses up to 250 mCi, is not associated with any long-term risk of infertility. The risks of infertility or birth defects are not different from those of the general population. Because the two children with birth defects were born to mothers treated either during pregnancy or 6 months before conception, it might be wise to suggest avoiding pregnancy for up to 1 year after 131I treatment.

Abnormalities, Radiation-Induced↗