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Biomedical subjects

M J Zhang

Publications and source records attributed to M J Zhang.

At least 37 records · Page 2Linked to original sources

Alcohol consumption and cigarette smoking increase the frequency of p53 mutations in non-small cell lung cancer.

Epidemiological studies have demonstrated a strong association between tobacco use and lung cancer; however, the genetic targets of these carcinogens and the role of other environmental agents in this process have yet to be defined. We examined the contribution of alcohol use and cigarette smoking top53 gene mutations in patients with non-small cell lung cancer. Mutations of the p53 gene were detected by sequence analysis in 105 patients with non-small cell lung cancer. Patient characteristics significantly associated with p53 gene mutations were determined using logistic regression. Mutations in the p53 gene were present in 53% of the patients (56 of 105). p53 mutations were more common in patients who used alcohol than in patients who consumed less than one drink per day (72 versus 39%; P = 0.003), and were detected more often smokers than nonsmokers (58% versus 10%, P = 0.02). Mutations in the p53 gene were present more often (P = 0.01) in alcohol drinkers who smoked cigarettes [76% (31 of 41)], than in nondrinkers (<1 drink per day) who smoked cigarettes [42% (20 of 48)] or in nondrinkers who did not smoke [14% (1 of 7)]. In conclusion, alcohol consumption and tobacco use are both associated with p53 mutations in non-small cell lung cancer. The link between exposure to both alcohol and tobacco and p53 mutations raises the possibility that alcohol may enhance the mutagenic effects of cigarette smoke in the lung.

Aged↗

Effect of nucleated marrow cell dose on relapse and survival in identical twin bone marrow transplants for leukemia.

The impact of cell dose (number of nucleated donor cells per kilogram recipient weight) on transplantation outcome is controversial and may differ for allogeneic and identical twin (syngeneic) bone marrow transplants. We studied the association between cell dose and outcome in 100 unmanipulated identical twin bone marrow transplantations for leukemia, reported to the International Bone Marrow Transplant Registry between 1985 and 1994, using Cox proportional hazards regression for multivariate analyses. Cell doses ranged from 0.3 to 7.4 x 10(8) nucleated cells/kg (median, 3.0 x 10(8)cells/kg). Median follow-up was 75 months. Five-year cumulative incidences of transplant-related mortality with high (more than 3 x 10(8) cells/kg) versus low (less than or equal to 3 x 10(8) cells/kg) cell doses were 2% (95% confidence interval [CI], 0% to 8%) versus 10% (95% CI, 4% to 20%), respectively. Five-year probabilities of leukemia-free survival were 53% (95% CI, 39% to 67%) and 37% (95% CI, 23% to 52%), respectively. In multivariate analysis, among patients surviving in remission at least 9 months after transplantation, those receiving high cell doses were at significantly lower risk for treatment failure (relapse or death) than those receiving low cell doses (RR, 0.27; 95% CI, 0.12 to 0.6; P =.001). Lower treatment failure resulted from fewer relapses in the high cell dose group (RR for relapse, 0.28; 95% CI, 1.2 to 0.66; P =.003). These findings suggest that outcomes after syngeneic bone marrow transplantation could be improved by transplanting more than 3 x 10(8) nucleated cells per kilogram. The benefit of high cell dose on relapse may represent a delayed graft-versus-leukemia effect.

Adolescent↗

[Analysis of heavy oil fractions in high-temperature coal tar by capillary gas chromatography/fourier transform infrared spectrometry].

Capillary gas chromatography-Fourier transform infrared spectrometry-gas chromatography retention indices (GC/FTIR-RI), combined with the linear relationship between retention value and boiling points for polycyclic aromatic hydrocarbons, performed the determination of the composition of heavy oil fractions in high-temperature coal tar. More than 70 and 61 compounds were separated and identified in heavy oil fractions F7(300-330 degrees C) and F8(330-360 degrees C) respectively. The results are useful in coal tar distillation processing and pollution monitoring when such compounds are present.

Anthracenes↗

[Studies on shape selective isopropylation products of coal tar naphthalene by gas chromatography/mass spectrometry].

Shape selective isopropylation products of coal tar naphthalene over different zeolite catalysts have been studied by capillary gas chromatography/mass spectrometry (CGC/MS) combined with computerized library search and manual interpretations of mass spectra. The analytical results have shown that products mainly consisted of some monosubstituted, disubstituted and a few trisubstituted naphthalenes. Except the low activity of HZSM-5 catalyst, all other zeolite catalysts have higher activity. HY and H beta catalytic activities were the highest, and their naphthalene conversions attained to 79.12 and 55.79 percent respectively, but their selectivities for 2-isopropylnaphthalene (beta-IPN), 2, 6-diisopropylnaphthalene (2, 6-DIPN) and 2, 7-diisopropylnaphthalene (2, 7-DIPN) were too low. ZM catalysts had good activity and much better selectivity, especially for ZM4-3, of which its 2,6-DIPN/2,7-DIPN ratio was 2.97. Therefore, some zeolite catalysts are recommended for shape selective isopropylation of coal tar naphthalene.

English Abstract↗

[Prediction and estimation on molar response values of alkanes by using molecular path vector].

A new method based on a novel molecular topological index vector, called the molecular path vector (MPV), of alkane molecules is proposed and employed for estimation and prediction of the molar response values of various alkanes. The novel MPV, p = (P1, P2, P3, P4, P5, P6, P7, P8, P9, P10)', which derived directly from the interaction terms of molecular graph, is used to characterize well molecular structures of all alkanes from one through ten or eleven carbon atoms. It showed that there exists very good correlation between the MPV elements and molar response values on both FID and TCD detectors in classical gas chromatography. Based on the given calibration set with different sample numbers and by using the practical multiple linear regression, the quantitative structure-response relationship (QSRR) equations, for the molar response values (SM) on both FID and TCD, are respectively given as follows: SM(FID) = 15.4004881 + 17.9905995 X1 - 0.1652116 X2 - 0.6974103 X3 - 0.8452390 X4 - 0.2671000 X5 - 1.5657273 X6 + 0.0944440 X7, n = 50, m = 7, r = 0.9976, ST = 26.132, SR = 1.965 1, Ev = 99.72%, RMS = 1.801, F = 1231.71 SM(TCD) = 11.9946996 + 29.1490916 X1 - 4.7451669 X2 - 3.7673385 X3 - 1.4948330 X4 - 1.6278831 X5 - 0.7934611 X6 - 3.0566093 X7, n = 32, m = 7, r = 0.9968, ST = 15.72, SR = 1.4310, Ev = 99.59%, RMS = 1.239, F = 531.227 where the independent descriptor variables, X1-X7, refer to the elements, P1, P2, P3, P4, P5, P6, P7 in the molecular path vector for all samples in both FID and TCD training sets; n, r, ST, SR, Ev, RMS and F are the sample number, regression coefficient, total standard deviation, standard residual deviation, explained variance, rooted mean squared error and F-statistic value, respectively. To test both models by using back-propagation neural network (BPNN) with the topological structure NN(7-4-2) and the cross validation through leave-one-out (LOO) procedure, the correlation coefficient of cross validation is over 0.96. Because there exists a quite good linear relationship between the molar responses and molecular path parameters, BPNN (r = 0.989 and 0.968) does not show its nonlinear advantage over multiple linear regression(MLR) (r = 0.9976 and 0.9968) in both presently examined cases, FID and TCD in the GC technique, for molecular modelling and quantitative prediction.

Alkanes↗

Testing for centre effects in multi-centre survival studies: a Monte Carlo comparison of fixed and random effects tests.

The problem of testing for a centre effect in multi-centre studies following a proportional hazards regression analysis is considered. Two approaches to the problem can be used. One fits a proportional hazards model with a fixed covariate included for each centre (except one). The need for a centre specific adjustment is evaluated using either a score, Wald or likelihood ratio test of the hypothesis that all the centre specific effects are equal to zero. An alternative approach is to introduce a random effect or frailty for each centre into the model. Recently, Commenges and Andersen have proposed a score test for this random effects model. By a Monte Carlo study we compare the performance of these two approaches when either the fixed or random effects model holds true. The study shows that for moderate samples the fixed effects tests have nominal levels much higher than specified, but the random effect test performs as expected under the null hypothesis. Under the alternative hypothesis the random effect test has good power to detect relatively small fixed or random centre effects. Also, if the centre effect is ignored the estimator of the main treatment effect may be quite biased and is inconsistent. The tests are illustrated on a retrospective multi-centre study of recovery from bone marrow transplantation.

Bone Marrow Transplantation↗

Modelling covariate adjusted mortality relative to a standard population.

A study of long term survival of 1487 patients given an allogeneic bone marrow transplant for acute myelogenous leukaemia and 729 patients given a transplant for severe aplastic anaemia was conducted by the International Bone Marrow Transplant Registry. One aim of this study is to determine if the mortality rates of these patients return after some period of time to the same mortality rate as in the general population. To examine this question a model for the relative mortality of a bone marrow transplant patient relative to a matched individual in the general population is presented. This model allows for different relative mortality rates depending on the risk factors the patient may have. We discuss an estimation procedure for this model and construct a test that the mortality rate in the transplanted population is the same as in the reference population over a given time interval.

Adolescent↗

Tacrolimus vs. cyclosporine immunosuppression: results in advanced-stage disease compared with historical controls treated exclusively with cyclosporine.

A phase HI comparative trial of tacrolimus- vs. cyclosporine-based graft-vs.-host disease (GVHD) prophylaxis for human leukocyte antigen (HLA)-identical sibling bone marrow transplantation showed less GVHD but poorer survival in the tacrolimus arm. To test the comparability of the two treatment arms with respect to baseline survival prognosis, a matched control study using exclusively cyclosporine-treated patients from the International Bone Marrow Transplant Registry (IBMTR) database was performed. Controls were matched (2:1) based on age (within 5 years), disease, and pretransplant disease status. Two-year survival for tacrolimus-treated clinical trial patients was similar to that of their cyclosporine-treated matched controls (27 and 24%, respectively), and 2-year survival of the cyclosporine-treated clinical trial patients was similar to that of their cyclosporine-treated matched IBMTR controls (42 and 45%, respectively). Consistent with the clinical trial results, the cyclosporine-treated IBMTR controls matched to the tacrolimus group had significantly poorer 2-year survival than the cyclosporine-treated IBMTR controls matched to the cyclosporine group (24 and 45%, respectively; p < 0.01). No significant difference was seen in GVHD between the cyclosporine-treated clinical trial patients and their matched controls; however, the tacrolimus-treated clinical trial patients had significantly less GVHD than their cyclosporine-treated IBMTR controls (p < 0.01). These results support the hypothesis that the survival difference in the phase III trial resulted from an imbalance in the underlying risk factors for death in the two groups rather than from the randomized immunosuppressive regimen.

Adolescent↗

Modeling random effects for censored data by a multivariate normal regression model.

A normal distribution regression model with a frailty-like factor to account for statistical dependence between the observed survival times is introduced. This model, as opposed to standard hazard-based frailty models, has survival times that, conditional on the shared random effect, have an accelerated failure time representation. The dependence properties of this model are discussed and maximum likelihood estimation of the model's parameters is considered. A number of examples are considered to illustrate the approach. The estimated degree of dependence is comparable to other models, but the present approach has the advantage that the interpretation of the random effect is simpler than in the frailty model.

Animals↗

Autotransplants for Hodgkin's disease in patients never achieving remission: a report from the Autologous Blood and Marrow Transplant Registry.

PURPOSE: Hodgkin's disease patients who never achieve complete remission with conventional chemotherapy (i.e., those with primary induction failure) have a poor prognosis. Some subjects who receive high-dose therapy with autologous hematopoietic progenitor-cell infusion experience prolonged progression-free survival. PATIENTS AND METHODS: Detailed records from the Autologous Blood and Marrow Transplant Registry (ABMTR) on 122 Hodgkin's disease patients who failed to achieve complete remission after one or more conventional therapy regimens and subsequently received an autotransplant between 1989 and 1995 were reviewed. RESULTS: Median age was 27 years (range, 7 to 57 years). Median time from diagnosis to transplantation was 14 months (range, 5 to 38 months). Most patients received high-dose chemotherapy without radiation for pretransplantation conditioning (n = 107). The regimen most frequently used was cyclophosphamide, carmustine, and etoposide (n = 47). Fifteen patients received total-body irradiation (n = 15). The graft consisted of bone marrow (n = 86), blood stem cells (n = 25), or both (n = 11). The 100-day mortality was 12% (95% confidence interval, 7% to 19%). Sixty patients (50%) were considered to have achieved complete remission after autotransplantation; 37 of these had negative imaging studies, whereas scan abnormalities of unknown significance persisted in 23 patients. Twenty-seven patients (22%) had no response or progressive disease after transplantation. Probabilities of progression-free and overall survival at 3 years were 38% (95% confidence interval, 28% to 48%) and 50% (95% confidence interval, 39% to 60%), respectively. In multivariate analysis, "B" symptoms at diagnosis and poor performance score at transplantation were adverse prognostic factors for outcome. CONCLUSION: Autotransplants should be considered for patients with Hodgkin's disease who do not achieve complete remission with conventional therapy.

Adolescent↗

Improving the outcome of bone marrow transplantation by using CD52 monoclonal antibodies to prevent graft-versus-host disease and graft rejection.

Graft-versus-host disease (GVHD) is a major cause of mortality and morbidity after allogeneic bone marrow transplantation, but can be avoided by removing T lymphocytes from the donor bone marrow. However, T-cell depletion increases the risk of graft rejection. This study examined the use of CD52 monoclonal antibodies to eliminate T cells from both donor marrow and recipient to prevent both GVHD and rejection. Seventy patients receiving HLA-identical sibling transplants for acute myelogenous leukemia (AML) in first remission were studied. An IgM (CAMPATH-1M) was used for in vitro depletion of the graft and an IgG (CAMPATH-1G) for in vivo depletion of the recipient before graft infusion. No posttransplant immunosuppression was given. Results were compared with two control groups: (1) 50 patients who received bone marrow depleted with CAMPATH-1M, but no CAMPATH-1G in vivo; and (2) 459 patients reported to the International Bone Marrow Transplant Registry (IBMTR) who received nondepleted grafts and conventional GVHD prophylaxis with cyclosporin A (CyA) and methotrexate (MTX). The incidence of acute GVHD was 4% in the treatment group compared with 35% in the CyA/MTX group (P <.001). Chronic GVHD was also exceptionally low in the treatment group (3% v 36%; P <.001). The problem of graft rejection, which had been frequent in the historic CAMPATH-1M group (31%), was largely overcome in the treatment group (6%). Thus, transplant-related mortality of the treatment group (15% at 5 years) was lower than for the CyA/MTX group (26%; P =.04). There was little difference in the risk of leukemia relapse between the treatment group (30% at 5 years) and the CyA/MTX group (29%). Survival of the treatment group at 6 months was better than the CyA/MTX group (92% v 78%), although at 5 years the difference was not significant (62% v 58%) and neither was the difference in leukemia-free survival (60% v 52%). We conclude that T-cell depletion is a useful strategy to prevent GVHD, provided that measures are taken to ensure engraftment. Using CAMPATH-1G to deplete residual host lymphocytes is a simple and practical method to do this. At least in AML, the beneficial reduction in GVHD can be achieved without an increased risk of relapse.

Alemtuzumab↗

Survival with bone marrow transplantation versus hydroxyurea or interferon for chronic myelogenous leukemia. The German CML Study Group.

Hydroxyurea, interferon, and HLA-identical sibling bone marrow transplantation are common therapies for chronic myelogenous leukemia (CML) in chronic phase. Which is best is controversial. The purpose of this study was to compare survival of patients with CML receiving HLA-identical sibling transplants versus hydroxyurea or interferon. The transplant cohort included 548 recipients of HLA-identical sibling transplants, reported to the International Bone Marrow Transplant Registry. The nontransplant cohort included 196 patients receiving hydroxyurea (n = 121) or interferon (n = 75) on a randomized trial of the German CML Study Group. Survivals were compared using proportional hazards regression with fixed and time-dependent variables to adjust for patient differences and changing risks over time. For the first 18 months after diagnosis, mortality was higher in the transplant than the nontransplant cohort (relative risk [RR], 5.85; P < .0001). From 18 to 56 months, mortality was similar (RR, 0.80; P = .38). After 56 months, mortality was lower in the transplant cohort (RR, 0.16; P < .0001). Seven-year survival probabilities (95% confidence interval) were 58% (50% to 66%) with transplant and 32% (22% to 41%) with hydroxyurea or interferon. There was a significant survival advantage for hydroxyurea or interferon in the first 4 years after diagnosis and for transplants starting 5.5 years after diagnosis. For transplants done within 1 year of diagnosis, the survival advantage for transplantation began earlier. Survival advantage for transplants was greater and occurred earlier in patients with intermediate- and high-risk prognostic features than in those with low-risk features. This study confirms higher early mortality, but a long-term survival advantage for HLA-identical sibling transplants over hydroxyurea or interferon in CML.

Adolescent↗

Tolerance of diverse amino acid substitutions at conserved positions in the nuclear export signal (NES) of HIV-1 Rev.

The effector domain of the Rev protein is a nuclear export signal (NES) that is responsible for transporting Rev and its bound congeners out of the nucleus and into the cytoplasm. Previous work has identified several critical residues in the NES and has led to the belief that NESs of the Rev type are necessarily leucine rich. Here we present the sequences of a large number of functional Rev molecules with NES mutations. The data indicate a previously unreported diversity in allowable residues at a number of positions, including each of the leucine residues previously considered essential.

Amino Acid Sequence↗

In vitro maturation of follicular oocytes of the Giant Panda (Ailuropoda melanoleuca): a case report.

The Giant Panda is an endangered species that would benefit from biotechnological assistance in reproduction. However, because there are only a few of these animals left in the world, scientists hesitate to use them for research procedures. We were fortunate to obtain ovaries from a Giant Panda that died of hepatic cirrhosis during the nonbreeding season. Oocytes were harvested within 4 h of death by dissecting the ovarian cortex in physiological saline and collecting the cumulus-oocyte complexes from the fluid, and then were classified into large (> 125 microns) and small (100 to 124 microns) follicular oocytes and placed in TCM199 supplemented with FSH (10 micrograms/mL) and LH (20 micrograms/mL). After culture for 22 h at 37 degrees C in air with 5% CO2, response was evaluated by growth of oocytes and presence of the first polar body. Of the 26 large follicular oocytes that were harvested, 12 were considered suitable for IVM, and 14 were degenerated, had a broken zona pellucida or had lost some cytoplasm. Of the 12 cultured oocytes, all grew to a mean diameter of 141.1(SD = +/- 6.7, n = 12), and 4 released the first polar body. None of the small follicular oocytes showed growth or other signs of maturation. We conclude from our preliminary results that it is possible to obtain functional Giant Panda oocytes from ovaries obtained post mortem during the nonbreeding season.

Animals↗

Graft-versus-leukemia effects in T lineage and B lineage acute lymphoblastic leukemia.

T and B lineage ALL cells express different levels of HLA-class II antigens, which may serve as targets for graft-versus-host disease (GVHD) and graft-versus-leukemia (GVL). The object of this study was to determine whether GVL effects after HLA-identical sibling bone marrow transplantation differed in T and B lineage ALL. We studied 1132 patients with ALL of T lineage (n = 416) or of B lineage (cALLa+) (n = 716) transplanted in first (n = 605) or second (n = 527) remission with bone marrow from an HLA-identical sibling donor, between 1982 and 1992, and reported to the IBMTR by 165 teams. Cox proportional hazards regression models were used to determine the relative risk (RR) of relapse in patients with acute (grades II-IV) or chronic GVHD vs patients without GVHD. Acute and chronic GVHD were considered as time-dependent covariates. Patients transplanted in first and second remission were analyzed separately. GVHD decreased relapse risks to a similar extent in T and B lineage ALL. For first remission transplants, relative risks of relapse for patients with vs those without GVHD was 0.34 for T lineage ALL and 0.44 for B lineage ALL. Corresponding relative risks in second remission transplants were 0.54 and 0.61. This study confirms earlier findings of an antileukemia effect of GVHD in ALL. This effect was similar in T lineage and B lineage ALL, despite probable differences in HLA-class II antigen expression.

Adolescent↗

Influence of protective isolation on outcome of allogeneic bone marrow transplantation for leukemia.

Various isolation strategies are used to prevent infections during bone marrow transplantation; data on their efficacy are lacking. We studied whether use of high efficiency particulate air filtration (HEPA) and/or laminar airflow (LAF) units affect transplant-related mortality (TRM) or survival in the first year after allogeneic transplantation. 5065 patients with leukemia receiving bone marrow transplants from an HLA identical sibling (n = 3982) or alternative related or unrelated donors (n = 1083) between 1988 and 1992 were reported to the International Bone Marrow Transplant Registry by 222 teams. Two types of isolation were considered: (1) conventional protective isolation with single patient room and any combination of hand-washing, gloves, mask and gown; and (2) HEPA and/or LAF. Cox proportional hazards regression models were used to determine the relative risks (RRs) of transplant-related mortality (TRM) and of deaths from any cause in patients treated in HEPA/LAF units compared to patients treated in conventional isolation. HLA-identical sibling and alternative donor transplants were analyzed separately. Risks of TRM and overall mortality in the first 100 days post-transplant were significantly lower among patients treated in HEPA/LAF units than in those treated conventionally. RRs of TRM were 0.76 (P = 0.009) for recipients of HLA-identical sibling transplants and 0.65 (P = 0.003) for recipients of alternative donor transplants. Correspondingly RRs of overall mortality were 0.80 (P = 0.02) and 0.65 (P = 0.0006). Decreased risks of TRM and of death in the first 100 days post-transplant resulted in significantly higher 1-year survival rates in patients treated in HEPA/LAF rather than in conventional isolation units. Use of HEPA and/or LAF to prevent infections decreases TRM and increases survival after allogeneic bone marrow transplants for leukemia.

Adolescent↗

Chemotherapy vs HLA-identical sibling bone marrow transplants for adults with acute lymphoblastic leukemia in first remission.

There is controversy about whether chemotherapy or an HLA-identical sibling bone marrow transplant is better treatment for adults with acute lymphoblastic leukemia (ALL) in first remission. A previous study of patients treated in 1980-1987 showed similar leukemia-free survivals with these approaches. We re-examined this issue in more recently treated patients receiving different chemotherapy. Chemotherapy subjects (n = 76) participated in trial ALL-87 of the Japan Adult Leukemia Study Group (JALSG). Transplant subjects (n = 214) were reported to the International Bone Marrow Transplant Registry (IBMTR). Treatment-related mortality, relapse and leukemia-free survival were compared after adjusting for differences in subject- and disease-related variables and time-to-treatment. Outcomes differed in persons < or = and >30 years of age. Five-year treatment-related mortality in persons < or =30 years was 3% (95% confidence interval, 0-12%) with chemotherapy vs 32% (23-41%; P < 0.0001) with transplants. The difference was greater among persons >30 years, 13% (2-31%) with chemotherapy vs 57% (43-69%; P < 0.0001) with transplants. Five-year relapse probability in persons < or =30 years was 69% (50-84%) with chemotherapy vs 22% (14-32%; P < 0.0001) with transplants. Among persons >30 years, 5-year relapse was 70% (53-85%) with chemotherapy vs 32% (20-45%; P < 0.0001) with transplants. Leukemia-free survival at 5 years was significantly worse with chemotherapy than with transplants in persons < or =30 years (30% (15-48%) vs 53% (44-63%; P = 0.02)) but not in persons >30 years (26% (13-41%) vs 30% (20-41%; P = 0.70)). We concluded that transplants result in more treatment-related deaths but fewer relapses than chemotherapy. Leukemia-free survival is better with transplants than chemotherapy in persons < or =30 years of age but comparable in older persons.

Adolescent↗