Biomedical subjects

A Peng

Publications and source records attributed to A Peng.

At least 19 recordsLinked to original sources

PubMed2006

Effect of induction therapy protocols on transplant outcomes in crossmatch positive renal allograft recipients desensitized with IVIG.

Here we retrospectively examine the efficacy of two antibody induction regimens using Zenapax or Thymoglobulin in patients with positive complement-dependent cytotoxicity crossmatches (CDC-CMXs) desensitized with IVIG (intravenous immunoglobulin). Between January 1999 and March 2005, 97 patients with (+) CDC-CMXs received kidney transplants (43 deceased donors/54 living donors). All patients received at least 2 g/kg IVIG (maximum four doses) until an acceptable CMX was obtained. Patients were divided into two groups: 1. IVIG + Zenapax (n = 58), 2. IVIG + Thymoglobulin (n = 39). A total of 94% of patients in Group 1 and 84% in G2 have at least 2 years of follow up. Patient and graft survival was 96%/84% in Group 1 and 100%/90% in Group 2, p = NS. The number and severity of AR episodes were similar (36% Group 1 vs. 31% Group 2, p = NS) as was the incidence of C4d (+) antibody-mediated rejection (AMR) (Banff Grade II/III) (22% Group 1 vs. 21% Group 2). Mean serum creatinines (SCrs) at 24 months were similar (Group 1: 1.4 +/- 0.7 vs. G2: 1.5 +/- 0.7 mg/dL). Induction therapy with Zenapax or Thymoglobulin results in excellent patient, graft survival and graft function at 2 years. There was no increased risk of viral infections or malignancies with either agent. Neither agent was effective in reducing the incidence of AMR.

Acute Disease↗

PubMed2006

Intravenous gammaglobulin (IVIG): a novel approach to improve transplant rates and outcomes in highly HLA-sensitized patients.

Intravenous immunoglobulin (IVIG) products are derived from pooled human plasma and have been used for the treatment of primary immunodeficiency disorders for more than 24 years. Shortly after their introduction, IVIG products were also found to be effective in the treatment of autoimmune and inflammatory disorders. Over the past 2 decades, the list of diseases where IVIG has a demonstrable beneficial effect has grown rapidly. These include Kawasaki disease, Guillain-Barre syndrome, myasthenia gravis, dermatomyositis and demyelinating polyneuropathy. Recently, we have described a beneficial effect on the reduction of anti-HLA antibodies with subsequent improvement in transplantation of highly HLA-sensitized patients as well as a potent anti-inflammatory effect that is beneficial in the treatment of antibody-mediated rejection (AMR). These advancements have enabled transplantation of patients previously considered untransplantable. These studies and relevant mechanism(s) of action will be discussed here.

Graft Rejection↗

PubMed2005

Herbal treatment for renal diseases.

Renal fibrosis is a common consequence of chronic kidney diseases (CKD). Standard therapy to prevent progression of CKD in western medicine includes dietary protein restriction, blood pressure control, angiotensin-converting enzyme inhibition and angiotensin receptor blockade. However, little is known about the renoprotective effects of Chinese herbal medicine. Cumulative evidence suggests that some Chinese herbal medicines, including Astragalus and a mixture of Astragalus plus Angelica, Ligusticum, Triptolide and Rhubarb, have a beneficial role in slowing the progression of CKD. This effect is multi-functional and multi-targeted, and is often associated with a reduction in proteinuria and the amelioration of dyslipidaemia, but not with changes in systemic blood pressure. These mechanisms include anti-inflammation and inhibition of TGF-b overproduction. On the other hand, some Chinese herbal medicines may be hazardous to patients with renal diseases. In this review, we discuss recent advances in the research of some Chinese herbs for pharmacological intervention of progressive renal diseases and kidney-related injuries.

Animals↗

PubMed2003

Intravenous immune globulin treatment inhibits crossmatch positivity and allows for successful transplantation of incompatible organs in living-donor and cadaver recipients.

BACKGROUND: Sensitization to human leukocyte antigens (HLA) is a significant barrier to transplantation. Currently, no proven therapy exists to improve access to transplantation for highly sensitized patients. Here, we report a novel approach using intravenous immune globulin to modulate anti-HLA antibody and improve the chances for successful transplantation. PATIENTS AND METHODS: Forty-five highly HLA-sensitized patients presented as candidates for living-donor kidney transplantation (n=28), cadaveric kidney transplantation (n=15), or heart transplantation (n=2). All patients had a positive CDC crossmatch (CMX) with their donors. In living-donor recipients, intravenous immune globulin (IVIG) was added to the CMX evaluation to determine whether blocking antibodies present in IVIG could inhibit cytotoxicity. For those who showed in vitro inhibition with IVIG (n=26), IVIG was administered (usually as a single dose, 2 g/kg) and the CDC CMX was repeated against the prospective donor immediately after IVIG infusion. If negative, the patient underwent transplantation with their living-donor kidney within 24 to 72 hr. A similar but modified protocol was performed for cadaver donor candidates, all of whom were highly sensitized and had had CMX positivity with multiple donors, negating transplantation. Reductions in CMX positivity, posttransplantation serum creatinine level, number and severity of rejection episodes, and patient and graft survival rates were determined. RESULTS: Forty-two patients underwent transplantation. IVIG treatment completely abrogated the donor-specific CMXs in 35 of 42 patients. In the remaining 7 patients, the CDC CMX was inhibited, but flow cytometry CMXs remained positive. A total of 13 (31%) of 42 recipients developed rejection episodes 3 to 49 days after transplantation. Three grafts (7%) were lost to rejection. Mean serum creatinine level at 24 months was 1.4+/-0.4 mg/dL. Patient and graft survival rates were 97.6% and 89.1%, respectively, at 24 months. CONCLUSIONS: The in vitro IVIG CMX technique predicts the ability of IVIG to reduce anti-HLA antibody levels in highly sensitized patients. Subsequent in vivo IVIG treatment of responders eliminates the positive CDC CMX and allows for successful transplantation. Thus a positive CMX result is not necessarily a contraindication for transplantation and allows access to transplantation for patients for whom it was previously contraindicated.

Adolescent↗

PubMed2002

Effect of La3+ on the activities of antioxidant enzymes in wheat seedlings under lead stress in solution culture.

In order to improve the plant ability to resist lead stress, effect of 0.05 mg/l La(NO3)3 on the activities of catalase (CAT), superoxide dismutase (SOD), the level of malondialdehyde (MDA) in wheat seedlings under lead stress was studied. The effect of La3+ on plant growth, chlorophyll content in wheat seedlings after adding 0, 50, 100 mg/l Pb(NO3)3 to the nutrient solution for 12 days was observed. The plants were grown in nutrient solution in a strictly controlled climate growth room. Effects of La3+ (with La treatment) compared with check groups was evidently observed. The activities of SOD and CAT in root were enhanced 0.45-1.69 times and 33.20-77.77% respectively and MDA content was reduced 11.05-27.49% in root after treatments from the second day till the end of the experiment. The activities of SOD and CAT was found to be increased slightly (P < 0.05) and MDA content decreased in shoot and root of wheat seedlings by La3+ under lead stress within five days after treatments compared with Pbl and Pb2 groups. It was assumed that antioxidant enzymes was found to be increased by La(NO3)3, the antioxidant potential of the wheat seedlings to resist lead stress enhanced. It is suggested that La3+ could be used to resist lead stress at the beginning under stress while the stress was not so serious.

Catalase↗

PubMed2001

Degradation of dye solution by an activated carbon fiber electrode electrolysis system.

Degradation of 29 dyes by means of an activated carbon fiber (ACF) electrode electrolysis system was performed successfully. Almost all dye solutions tested were decolorized effectively in this ACF electrolysis process. Internal relationships between treatment mechanisms and chemical composition of the dye have been discussed in this paper. Generally, it is shown that higher solubility leads to greater degradation in the process. Dyes with many -SO3-, COO-, -SO2NH2, -OH, hydrophilic groups, and azo linkages are susceptible to reduction. However, dyes with many -C=O, -NH-and aromatic groups, and hydrophobic groups, tend to be adsorbed. For dyes with -SO3-, COOH and -OH groups, if their molecules linearly spread in solution and have a significant tendency to form colloids by hydrogenous bonding, they also tend to be adsorbed and flocculated. Typical dynamic electrolysis of dye Acid Red B, Vat Blue BO and Disperse Red E-4B shows how the two major mechanisms, degradation and adsorption, act differently during treatment. Reduction occurs evenly during treatment. During the dominant adsorption process, after certain amount of iron is generated, colloid precipitation occurs and TOC and color are rapidly removed.

Adsorption↗

PubMed2001

Hydrogen peroxide promotes transformation of rat liver non-neoplastic epithelial cells through activation of epidermal growth factor receptor.

Previous studies demonstrated that hydrogen peroxide (H(2)O(2)) is a tumor promoter in the rat liver epithelial cell line T51B. We investigated the pathway linking H(2)O(2) to tumor promotion. H(2)O(2) can directly induce tyrosine phosphorylation of epidermal growth factor receptor (EGFR). H(2)O(2) and epidermal growth factor exerted similar effects on the induction of early growth response genes, disruption of gap junction communication, triggering of calcium inflow, and promotion of transformation. Furthermore, the effect of H(2)O(2) on tumor promotion was blocked by abrogation of EGFR activation. Our results suggested that tumor promotion by H(2)O(2) is mediated mainly through activation of EGFR in T51B cells.

Animals↗

PubMed2001

Calcium channel antagonist verapamil inhibits neointimal formation and enhances apoptosis in a vascular graft model.

BACKGROUND: The potential of the calcium channel antagonist verapamil to cause apoptosis (programmed cell death) is of considerable importance in arterial injury where the loss of smooth muscle cells may contribute to a reduction in intimal hyperplasia development. The aim of this study was to determine whether verapamil induces vascular cell apoptosis after carotid artery synthetic grafting. METHODS: Thirty-two adult-female Merino sheep received gelatin sealed fusiform shape-Dacron grafts into the left common carotid artery at day 0. After operation animals were randomly allocated to either a control group or one of three treatment groups (groups 2, 3, and 4). Group 1 animals (n = 9) received no treatment. For the treatment groups, intravenous verapamil was given at a rate of 0.5 mg/kg per day in two divided doses. Group 2, 3, and 4 sheep were treated for 1, 2, and 4 weeks, respectively. Animals were sacrificed at 4 weeks. Apoptosis was detected by terminal deoxynucleotidyl transferase-mediated dUTP-fluorescent labelling. Proliferating cells and their phenotype were determined by doublestaining with antiproliferation cellular nuclei antigen and anti-alpha-actin or anti-HAM-56. RESULTS: There were significantly more apoptotic cells in the perigraft adventitia in the 4-week treatment group than in the control group (P <0.05). The average number of proliferating cells at 2 and 4 weeks in the intima were significantly less than in the control (P <0.05). The average numbers of macrophages inside graft matrix in the 2 and 4 weeks treatment groups were significantly less than for the control (P <0.05). The number of proliferating cells inside the graft was significantly lower at 4 weeks compared with control (P <0.05). There was negative correlation between intimal PCNA expression and perigraft apoptotic expression level (P <0.05). CONCLUSION: The antihypertensive agent verapamil inhibits intimal hyperplasia through enhancing adventitial cell apoptosis and inhibiting intimal cell proliferation after vascular grafting.

Analysis of Variance↗

PubMed2001

Study on the kinetics of cerium(III) adsorption-desorption on different soils of China.

The kinetics of Ce(III) adsorption-desorption on four typical soils in China has been studied by using the batch method with the radioactive nuclide 141Ce. Results indicated that Ce(III) adsorption was rapid and nearly finished in less than 0.5 min. Desorption procedure was about completed in 1-30 min in the tested soils. Ce(III) desorption equilibrium times vary with different soils. The amounts of Ce(III) desorption on different soils in the same time were different. The Elovich equation proved to be the best models for fitting the data of Ce(III) desorption reactions in fluvo-aquic soil and black soil; and the parabolic-diffusion equation was the best model in red earth and loess soil.

Adsorption↗

PubMed2001

Comparative studies on the concentration of rare earth elements and heavy metals in the atmospheric particulate matter in Beijing, China, and in Delft, The Netherlands.

Atmospheric particulate matter (APM) was collected at three sampling sites in Beijing, China, from February to June 1998. The concentrations of rare earth elements (REE) and cobalt (Co), zinc (Zn), copper (Cu), cadmium (Cd) and lead (Pb) in the APM were determined by inductively coupled plasma mass spectrometry (ICP-MS). The results obtained in Beijing, China, were compared to that obtained in Delft, the Netherlands, in 1997. The influence of coal combustion was considered. The results demonstrated that the content of APM, the concentrations of REE and Co, Zn, Cd, Pb in the APM in Beijing, China, were higher than that in Delft, the Netherlands. From the ratios of La to Ce, and La to Sm, which may be used as tracers for the origin of the REE, it is concluded that the origins of REE in China differ from those in the Netherlands.

Air Pollutants↗

PubMed2001

The effect of fulvic acid on the dose effect of selenite on the growth of wheat.

The effect of fulvic acid on the dose effect of selenite has been studied by using the hydroponics culture of wheat in the presence of selenite and fulvic acid (FA). The bioavailability of Se was investigated by 5 morphological end points and 12 biological and biochemical end points at different phases of growth of wheat seedling and seed germination. The "platform" of the dose effect observed indicates that the presence of FA can have both the beneficial effects and antagonists on the toxicity of Se to a certain extent.

Benzopyrans↗

PubMed2001

[The absorbed rate and distribution rule of rare earth elements in wheat by 141Ce as tracer].

The study on absorption, distribution rules and transportation rates of cerium in the interface of water-wheat by 141Ce in culture solution were carried out. The results showed that the concentrations of cerium in wheat seedling were gradually increased during the experiment, and so did the same after increasing the concentration of cerium adding in the culture solution. The concentrations of cerium in roots of winter wheat were significantly high than that in tops (steam & leave). The absorption rates of cerium in wheat with different treatments of cerium were distinct. The quantitative formulas, which describe the rule of absorption rate and culture time, was given resulting from the fit of the experimental data.

Adsorption↗

PubMed2001

[Effect of phosphate on the exchangeable form and the bioavailability of exogenous neodymium in soil].

Effects of phosphate on the exchangeable form and the bioavailability of exogenous neodymium (Nd) in soil were studied with 147Nd isotopic tracer. Exchangeable Nd was extracted with solution (pH8.2) of NaAc. The results indicated that Nd beyond 99.5% was adsorbed by soil whether phosphate exists in soil or not. Phosphate can precipitate dramatically Nd3+. And the Nd phosphate precipitates may set limits on the concentration of exchangeable Nd observed in soil. KH2PO4 ranging from 0.3 g.kg-1 to 1.5 g.kg-1 make a uniform impact on the exchangeable form of Nd. In addition, phosphate in soil can inhibit wheat seedling to absorb Nd. The concentration of exchangeable Nd is correlated significantly with the content of Nd in wheat seedling.

Biological Availability↗

PubMed2001

[Effect of lead stress on the activity of antioxidant enzymes in wheat seedling].

The changes of the antioxidant enzyme activity, such as superoxide dismutase (SOD), catalase (CAT) and malondialdehyde (MDA) were researched through nutrient solution culture. The results showed that the activity of SOD in shoot and root were significantly enhanced under lead stress. The activity of CAT in root was also improved, but the degree was not bigger than that of SOD activity. However, the MDA content in shoot and root was significantly higher than that of check group, it suggested that the membrane system were damaged by lead stress. The experiments also revealed that the shoot of wheat seedling was influenced by lead stress greatly stronger than that of root.

Catalase↗

PubMed2000

Disease progression in sporadic inclusion body myositis: observations in 78 patients.

Functional decline for each decade at symptom onset and need for cane, walker, or wheelchair were assessed in 78 biopsy-proved patients with sporadic inclusion body myositis. Patients with disease onset between 40 and 59 years used a walker after 10.2 +/- 5.8 years, whereas those with disease onset between 60 and 79 years used a walker after 5.7 +/- 5.0 years (p = 0.05). Because patients progress faster to disability when symptoms begin after the age of 60, age at disease onset may define patient subsets for stratification in clinical trials.

Adult↗

PubMed2000

Cyclosporine and tacrolimus-associated thrombotic microangiopathy.

The development of thrombotic microangiopathy (TMA) associated with the use of cyclosporine has been well documented. Treatments have included discontinuation or reduction of cyclosporine dose with or without concurrent plasma exchange, plasma infusion, anticoagulation, and intravenous immunoglobulin G infusion. However, for recipients of organ transplantation, removing the inciting agent is not without the attendant risk of precipitating acute rejection and graft loss. The last decade has seen the emergence of tacrolimus as a potent immunosuppressive agent with mechanisms of action virtually identical to those of cyclosporine. As a result, switching to tacrolimus has been reported to be a viable therapeutic option in the setting of cyclosporine-induced TMA. With the more widespread application of tacrolimus in organ transplantation, tacrolimus-associated TMA has also been recognized. However, literature regarding the incidence of the recurrence of TMA in patients exposed sequentially to cyclosporine and tacrolimus is limited. We report a case of a living donor renal transplant recipient who developed cyclosporine-induced TMA that responded to the withdrawal of cyclosporine in conjunction with plasmapheresis and fresh frozen plasma replacement therapy. Introduction of tacrolimus as an alternative immunosuppressive agent resulted in the recurrence of TMA and the subsequent loss of the renal allograft. Patients who are switched from cyclosporine to tacrolimus or vice versa should be closely monitored for the signs and symptoms of recurrent TMA.

Adult↗

PubMed2000

Study on the dose-effect relationship of selenite with the growth of wheat.

The wheat in hydroponics culture has been chosen as a model to study the dose-effect relationship of selenite with its growth. Five different morphological end points and 12 different biological and biochemical end points during different phases of growth of wheat seedling and seed germination have been measured and analyzed. A dose-effect relationship of selenite with the growth of wheat has been obtained from data analysis. The results shows that critical threshold for beneficial effect is about 1.0 mg Se/L, and the critical threshold for adverse effect is about 5.0 mg Se/L in hydroponics culture. From the result of product of lipid peroxidation, it is assumed that the role of selenium for plant is related to the oxy-radical reaction.

Dose-Response Relationship, Drug↗

PubMed2000

Chromosome abnormalities in ovarian adenocarcinoma: III. Using breakpoint data to infer and test mathematical models for oncogenesis.

Cancer geneticists seek to identify genetic changes in tumor cells and to relate the genetic changes to tumor development. Because single changes can disrupt the cell cycle and promote other genetic changes, it is extremely hard to distinguish cause from effect. In this article we illustrate how 7 techniques from statistics, theoretical computer science, and phylogenetics can be used to infer and test possible models of tumor progression from single genome-wide descriptions of aberrations in a large sample of tumors. Specifically, we propose 4 tree models for tumor progression inferred from the large ovarian cancer data set described in the first 2 articles in this series. The models are derived from 2 different methods to select the non-random genetic aberrations and 2 different methods to infer the trees, given a set of events. Various aspects of the tree models are tested and extended by 5 methods: overall tests of independence, likelihood ratio tests, principal components analysis, directed acyclic graph modeling, and Bayesian survival analysis. All our methods lead to strikingly consistent conclusions about chromosomal breakpoints in ovarian adenocarcinoma, including (1) the non-random breakpoints in ovarian adenocarcinoma do not occur independently; (2) breakpoints in regions 1p3 and 11p1 are important early events and distinguish a class of tumors associated with poor prognosis; and (3) breakpoints in 1p1, 3p1, and 1q2 distinguish a class of ovarian tumors, and the breaks at 1p1 and 3p1 are associated with poor prognosis.

Adenocarcinoma↗