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Biomedical subjects

Z Chen

Publications and source records attributed to Z Chen.

At least 1,081 records · Page 60Linked to original sources
PubMed1996

Retinoic acid regulatory pathways, chromosomal translocations, and acute promyelocytic leukemia.

Retinoic acids (RAs) exert a broad range of physiologic actions during embryonic development and adult life. Two families of RA receptors, retinoic acid receptor (RAR) and retinoid X receptor (RXR), have been identified. The therapeutic effect of all-trans-RA (ATRA) in induction of remission for acute promyelocytic leukemia (APL) has largely been proved, and this has, over the past 10 years, greatly stimulated research on oncogenesis and RA-regulated differentiation pathways. In APL, one of the RAR genes, RARA, is fused to PML in the great majority of patients as a result of the chromosomal translocation t(15; 17). However, a small subset of APL patients have a different fusion gene, PLZF-RARA, resulting from the variant translocation t(11;17). A third translocation, t(5;17), in which the NPM gene is fused to RARA, has been described. Current data suggest that PML-RAR alpha and PLZF-RAR alpha fusion receptors may play an important role in the development of APL and that PML-RAR alpha could be the target of ATRA differentiation therapy. Characterization of the genes regulated by retinoic acid may open up new prospects for an understanding of the mechanisms of ATRA differentiation therapy for APL and may help to extend the concept of cancer-targeting treatment to other types of leukemias or solid tumors.

Adult↗
PubMed1996

Children's analogical problem solving: the effects of superficial, structural, and procedural similarity.

Two experiments with children between 5 and 8 years of age were designed to determine the effects of different types of similarity on analogical problem solving and to explore the cognitive components responsible for these effects. Three dimensions of similarity shared by the source and target problems were manipulated, and children's problem-solving performance was assessed with multiple measures. The results indicate that superficial and structural similarity facilitated the process of drawing analogies. More importantly, the present research demonstrated that procedural similarity influenced the process of applying analogues. The results also indicate that children as young as 5 and 6 years of age are capable of detecting and utilizing similarities in superficial features, structural relations, and procedural operations. Theoretical implications are discussed.

Child↗
PubMed1996

Identification of a novel missense mutation in the cardiac beta-myosin heavy chain gene in a Chinese patient with sporadic hypertrophic cardiomyopathy.

The exons 13, 16, 21 and 23 of cardiac beta-myosin heavy chain (MHC) gene from 32 Chinese patients with hypertrophic cardiomyopathy were analyzed by the polymerase chain reaction and the DNA single strand conformation polymorphism (PCR-SSCP) procedure. The results showed an altered SSCP in exon 13 of one patient. Sequencing analysis revealed that the patient had a G to T transversion in codon 383, resulting in the substitution of Lys by Asn. The missense mutation was also confirmed by Southern blot hybridization with an allele-specific oligonucleotide probe. Because it was found at a residue highly conserved through evolution, this mutation is likely to be the cause of hypertrophic cardiomyopathy in the patient. Because her parents and child were neither clinically nor genetically affected, it was concluded that the mutation in this patient arose de novo and was not passed to her child. This is the first report of a mutant cardiac beta-MHC gene in the Chinese population. Also, it is a novel missense mutation of the cardiac beta-MHC gene.

Adult↗
PubMed1996

Strain-dependent differences in the human cytomegalovirus replication origin.

The nucleotide sequence of the human cytomegalovirus replication origin of strain Towne (an AatII-SacI fragment corresponding to nt 90372-94637 of strain AD169) was determined and compared with AD169. Two differences were found in the nucleotide sequence level. One was the alteration of structural organization (a major difference): a 189-bp region of AD169 (nt 93337-93525) was directly repeated three times in Towne. The other was a change in the nucleotide residue level including substitution, insertion, or deletion (a minor difference). The divergent residues were predominantly localized within the nt 92591-92855 region of AD169. A replication assay revealed that replication ability remained after deletion of the 189-bp repeat but disappeared after either a 1.5-kb deletion from the AatII end or a 0.9-kb deletion from the SacI end. The 1.5- and 0.9-kb regions were relatively conserved. These results indicate that at least two regions essential for replication ability lie outside of both the relatively variable region and the 189-bp repeat and suggest that these essential regions support replication even with a spatial separation of either one (AD169) or three repeats (Towne) of the 189-bp region.

Base Sequence↗
PubMed1996

Effect of huoxuequyu recipe on erythrocyte ultrastructure and membrane ATPase activity in rats with passive smoking.

The effect of "Huoxuequyu" recipe on erythrocyte membrane Ca(2+)-ATPase activity, Na(+)-K(+)-ATPase activity and erythrocyte ultrastructure in rats exposed to passive smoking were observed. The erythrocyte membrane Ca(2+)-ATPase activity and Na(+)-K(+)-ATPase activity were found to be decreased in the model group as compared with the control group (P < 0.01, P < 0.01), while no significant difference existed between the treated group and the control group (P > 0.05). Our results also showed that there were more deformed red blood cells in model group than in control group under TCM and SEM (P < 0.0001). No significant difference was found between control group and treated group (P > 0.05). Furthermore, these findings indicated that "Huoxuequyu" recipe, a prepared natural herbal medicine, may be involved in modulation of the activity of erythrocyte membrane enzymes, thereby protecting erythrocyte membrane, so as to improve the erythrocyte function.

Adult↗
PubMed1996

Phenotypic and functional assessment of intraepithelial lymphocytes (IEL) isolated from rat colon and small bowel.

We have compared the proliferative potential of IELs isolated from rat colon (CIEL) and small bowel (SBIEL), and compared this with that observed using spleen lymphocytes. Unless additional irradiated spleen cells were added as a source of accessory cells, both IEL populations show poor proliferation in response to Con A stimulation. The CD4/CD8 ratio in spleen, SBIEL and CIEL was markedly different (3:1, 1:3, and 1:1, respectively). Cells expressing surface markers characteristic of macrophages were not routinely found in SBIELs. Both IEL preparations inhibited spleen cell proliferation in response to Con A or immobilized anti-CD3, and produced a soluble factor(s) capable of causing similar inhibition. For CIEL this inhibition was dependent upon a proliferation-independent but cell-cell contact dependent event.

Animals↗
PubMed1996

A case of therapy-related extramedullary acute promyelocytic leukemia.

We report a patient with extramedullary acute promyelocytic leukemia (APL) occurring after radiation therapy for carcinoma of the prostate. To the authors' knowledge, this patient represents the first case of cytogenetically and fluorescence in situ hybridization (FISH) confirmed therapy-related extramedullary APL. In contrast to the majority of previously reported t-APL, this case underwent a very unfavorable course.

Aged↗
PubMed1996

Long-term follow-up of minimal residual disease in childhood acute lymphoblastic leukemia patients by polymerase chain reaction analysis of multiple clone-specific or malignancy-specific gene markers.

Two types of markers, namely the clone-specific markers including T-cell receptor (TCR) gamma, TCR delta, and Ig heavy-chain (IgH) gene rearrangements, and malignancy-specific fusion gene mRNA such as SIL-TAL-1, BCR-ABL, and HRX-partner genes, were investigated by molecular biology techniques in 65 Chinese patients with acute lymphoblastic leukemia (ALL). In combination, these markers were informative among 96% of patients. Minimal residual disease (MRD) was followed up in 23 of these patients with available materials over a period varying from 8 to 54 months with at least one leukemia-specific probe. In most children, MRD was decreased continuously to an ultimately undetectable level within 6 to 12 months after remission induction therapy. One patient exhibited low-level residual leukemic cells for 4 years before the MRD turned negative. Another patient remained in complete remission for 45 months, although a positive signal was detected at 34 months using TCR delta probe, but was negative with a TCR gamma marker which was positive at presentation. In three patients who relapsed, MRD either persisted through the clinical course or became positive and eventually increased 3-11 months before clinical relapse. These data suggested that the combined use of multiple gene markers is a valuable tool for the PCR-based MRD detection, since it can cover most ALL patients. Furthermore, long-term follow-up of MRD is helpful for determining the dosage as well as the period of maintenance chemotherapy and for predicting impending relapse.

Base Sequence↗
PubMed1996

A retrospective lung cancer mortality study of people exposed to insoluble arsenic and radon.

The incidence of lung cancer for workers who had been exposed to insoluble arsenic in four mines was found to be 290/10(5). A dose-dependent decrease in the incidence was associated with a reduction in the concentration of insoluble arsenic in the air. The content of arsenic (expressed as the geometric mean) in the lung of subjects exposed to insoluble arsenic was 51.4 micrograms/g per dry lung tissue which was 17 times higher than the value of 3.0 micrograms/g per day lung tissue found in control groups. Moreover, the content of arsenic was found to correlate with the number of years working in the mine and with the incidence of lung cancer. Metabolic studies of arsenopyrite showed that it is converted to products such as arsenous acid, arsenic acid, methyl arsenate and dimethyl arsenate, which are identical to those generated from As2O3. Although these metabolic products are formed at a lower rate, they nonetheless show that arsenopyrite should be considered a carcinogen. Potential carcinogens such as As, Cr, Ni, Be, and Cd were evaluated in lung specimens of miners with lung cancer and compared with values obtained in controls using logistic regression analysis. Only As was found to be significantly associated with lung cancer. The concentration of As in lung tissues correlated well with the amount found in the air of the mining environment. A retrospective/prospective interference epidemiological investigation performed over a 40-year period showed that the risk of radon had been overestimated. After regulatory measures were implemented in the mines to control for exposure to Rn, the risk of exposure to Rn was found to be RR/WLM (relative risk per working level month) = 0.17%, which was 9 times lower than the values previously estimated.

Arsenic↗
PubMed1996

An analysis of antigen-antibody binding kinetics for biosensor applications utilized as a model system: influence of non-specific binding.

The influence of non-specific binding on the specific binding of antigen in solution to antibody immobilized on a biosensor surface is presented for first-, one and a half-, second-, and other order reactions occurring under external diffusion-limited conditions. Both single-step and dual-step binding of antigen to antibody is considered. For a half-order reaction the value of the ratio of non-specific binding to specific binding (alpha) does not affect the rate of specific binding since a single curve represents the binding curve for alpha = 0 to 0.5. An increase in the alpha value leads to a decrease in the rate of binding and in the amount of antigen bound specifically to the antibody on the surface for first-, one and a half-, and second-order reactions. Also, an increase in the reaction order increases the sensitivity of the specific binding to the alpha value. An increase in the antigen concentration in solution increases the amount and the rate of specific binding for first-, one and a half-, and second-order reactions. The introduction of non-specific binding leads to complexities in the specific binding of the antigen for the one and half- and second-order reactions as the antibody concentration on the surface is varied. When non-specific binding is present there is an optimum value of the antibody concentration on the surface that yields the maximum rate and amount of antigen specifically bound for one and a half- and second-order reactions. Though this optimum amount of antibody immobilized on the surface is the same for the one and a half- and second-order reactions, it is different for different alpha values. No such complexities are observed for first-order reactions. The inclusion of non-specific binding in the analysis provides a more realistic picture of the binding of the antigen in solution to the antibody immobilized on the surface. The figures that show the numerically calculated binding rates for different orders when non-specific binding is present, represent the most useful part of the analysis for readers who are interested in constructing biosensors, and should assist in the control and manipulation of these interactions at the surface. These curves can be used to interpret a far from ideal binding of antigen to an immobilized antibody surface or vice versa. More-or-less all of the analysis should also be applicable to analytical systems that would not be classified as biosensors (that is, immuno and receptor assays).

Antibodies↗
PubMed1996

Lipid peroxidation of mitochondrial membrane induced by D1: an organic solvent extractable component isolated from a crude extract of burn eschar.

D1, an organic solvent extractable component of an extract from burn eschar was characterized and the mechanism of its inhibitory effect on mitochondrial respiratory functions was investigated. Using silicic acid column chromatography, it was found that D1 consisted of two parts: a toxic simple lipid and a non-toxic complex lipid. Six subunits were obtained by further silicic acid column chromatography, among them, the no. 4 and no. 6 were toxic. Infrared spectrometric studies showed that no. 4 consisted of esters, while no. 6 were peroxides. D1 also contained large amounts of malonaldehyde (MDA) and lipid hydroperoxides (ROOH). Vitamin E was found to prevent the inhibitory action of D1 on mitochondrial function and to reduce the amount of MDA produced. However, if vitamin E was introduced after the addition of D1 the inhibition could not be prevented, although there was still a reduction in MDA production; therefore, MDA per se was probably not the cause of the inhibition. D1 induced ROOH formation in mitochondrial membranes. Cumene hydroperoxide, an organic hydroperoxide, was capable of inhibiting the mitochondrial function. This inhibitor action was blocked by vitamin E. It is speculated that ROOH in D1 is probably the element that inhibits mitochondrial function. That D1 caused lipid peroxidation of membrane lipid was also proved by analysing the fatty acid composition of mitochondrial membranes before and after treatment with D1. It was found that the amount of polyunsaturated fatty acids decreased and that of saturated fatty acids increased after incubation with D1, a direct proof that lipid peroxidation has occurred. Lipid peroxidation of the membrane lipid was the result of the action of oxygen free radicals. This process was best shown by a chemiluminescence study. In this experiment, D1 induced chemiluminescence which was dose-dependently related to the amount of D1 used. This was probably the most direct proof that D1 caused lipid peroxidation of membrane lipid resulting in damage of the mitochondria.

Burns↗
PubMed1996

A fractal analysis of the influence of non-specific binding on antigen-antibody binding kinetics for biosensor applications.

A fractal analysis of the influence of non-specific binding on the specific binding of antigen in solution to antibody immobilized on a biosensor surface is presented for first-, one and a half-, second, and other-order reactions occurring under external diffusion-limited conditions. Both single-step and dual-step binding of antigen in solution to antibody immobilized on the surface is considered. For a first-order reaction, an increase in the fractal parameters, b, leads to a decrease in the amount of antigen in solution bound specifically to the antibody on the surface when non-specific binding is either absent or present. The presence of non-specific binding leads to a decrease in the amount of antigen bound to the antibody on the surface. For a one and a half- and for second-order reactions and when non-specific binding is either absent or present to a small degree (alpha = 0.01), an increase in the fractal parameter, b, leads to a decrease in the amount of antigen bound specifically to the antibody immobilized on the biosensor surface. However, for an alpha value of 0.1, the maximum rate and the amount of antigen bound specifically to the antibody immobilized on the biosensor surface is obtained for fractal parameter values of 0.2 and 0.4, and 0.4 for the one and a half- and for second-order reactions, respectively. Apparently, some amount of heterogeneity is helpful in obtaining the optimum amount and rate of antigen in solution bound specifically to the antibody on the surface for reaction orders higher than one. The applicability of the approach to real antibody surfaces is demonstrated.

Antigen-Antibody Reactions↗
PubMed1996

Physiologic (intraindividual) variation of serum prostate-specific antigen in 814 men from a screening population.

OBJECTIVES: We measured the intraindividual variation of prostate-specific antigen (PSA) in the serum of healthy men screened for prostate cancer. METHODS: We used a fully automated PSA assay system (ACS: 180 assay) to evaluate a screening population of 814 men (mean age, 63.3 years; range, 50 to 79 years) without documented prostate cancer or prostate surgery. A second blood sample was drawn 15 to 183 days after the first specimen (mean, 80 days). RESULTS: In the ACS PSA ranges of 0 to 7.2 ng/mL, 7.3 to 17.9 ng/mL, and 18.0 ng/mL or greater (O to 4 ng/mL, 4 to 10 ng/mL, and 10.0 ng/mL or greater by the Tandem-R assay), the mean coefficient of variation of the first and second blood drawn was 20%, 12%, and 10%, respectively. In 435 men whose first blood samples were measured twice for PSA difference (interassay or run-to-run variation), the intraindividual variation in the range of 0 to 7.2 ng/mL was significantly larger than the interassay variation, which was also true the 7.3 to 17.9 ng/mL range. In the range of 0 to 7.2 ng/mL, 251 of 695 (36%) showed a 20% or greater relative increase and 69 of 695 (10%) showed a 1.3 ng/mL (0.75 ng/mL by the Tandem-R assay) or greater absolute increase of PSA at the second blood sample. CONCLUSIONS: We conclude that in the low ranges of PSA concentrations, one should consider the possibility of substantial intraindividual variation when interpreting serial PSA measurements.

Aged↗
PubMed1996

Lymphocyte proliferation response to extracts from different latex materials and to the purified latex allergen Hev b 1 (rubber elongation factor).

BACKGROUND: Type I allergy to latex is a growing problem, especially among health care workers. A detailed study of the peripheral blood cell responses to latex allergens has not been reported. METHODS: Peripheral blood mononuclear cells of patients and healthy subjects were isolated and stimulated with protein extracts from latex sap and latex gloves and the purified latex allergen Hev b 1 (rubber elongation factor) at different concentrations to determine the antigen-specific proliferation response. The examined patients were sensitized to latex by occupational exposure (n = 23) and had rhinitis, conjunctivitis, contact urticaria, and/or asthma. Two control groups of nonsensitized subjects were studied: one occupationally exposed to latex (n = 8), and the second, not exposed to latex (n = 8). RESULTS: In general, only latex-exposed subjects responded to the different latex antigen preparations. Lymphocyte proliferation responses to latex sap extract were found in 65% of latex-sensitized subjects and in 37.5% of the latex-exposed healthy subjects. Latex glove extract induced a significant proliferative responses in 47.8% of latex-sensitized patients and in 25% of the latex-exposed individuals. Hev b 1 induced lymphocyte proliferation responses in 52% of the latex-sensitized patients and in 25% of the latex-exposed subjects indicating that Hev b 1 is relevant antigen in these latex-sensitized and latex-exposed groups. Peripheral blood mononuclear cells of 39.1% of the latex-sensitized subjects responded to all three allergen preparations (latex sap and latex glove extract, as well as Hev b 1). We could find no correlation between latex-specific IgE level and latex-induced lymphocyte proliferation response. CONCLUSION: Our data indicate that the 14 kd protein Hev b 1 is a relevant allergen in health care workers. It can be detected by specific IgE antibodies to Hev b 1, as well as in lymphocyte proliferation assay. In addition, our study suggests that antigen-specific proliferation response to latex is associated with exposure to latex, but not with the level of specific latex IgE. This may be useful for the evaluation and prediction of latex hypersensitivity development.

Adult↗
PubMed1996

New triterpenoid saponins from Gynostemma pentaphyllum.

Three new triterpenoidal saponins (1-3), together with the known compound 4, were isolated from a MeOH extract of the aerial parts of Gynostemma pentaphyllum. Their structures were elucidated on the basis of chemical and spectral methods, such as 1H-1H DQFCOSY, HMQC, HMBC, and TOCSY NMR spectra. The aglycon moiety of 1 and 2 is a new dammarane-type triterpene 12-oxo-2 alpha, 3 beta, 20 (S)-trihydroxydammar- 24-ene.

Carbohydrate Sequence↗