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Biomedical subjects

Wei Chen

Publications and source records attributed to Wei Chen.

At least 127 records · Page 7Linked to original sources
PubMed2006

Manipulation of image intensity distribution at 7.0 T: passive RF shimming and focusing with dielectric materials.

PURPOSE: To investigate the effects of high dielectric material padding on RF field distribution in the human head at 7.0 T, and demonstrate the feasibility and effectiveness of RF passive shimming and focusing with such an approach. MATERIALS AND METHODS: The intensity distribution changes of gradient-recalled-echo (GRE) and spin-echo (SE) images of a human head acquired with water pads (dielectric constant = 78) placed in specified configurations around the head at 7.0 T were evaluated and compared with computer simulation results using the finite difference time domain (FDTD) method. The contributions to the B(1) field distribution change from the displacement current and conductive current of a given configuration of dielectric padding were determined with computer simulations. RESULTS: MR image intensity distribution in the human head with an RF coil at 7.0 T can be changed drastically by placing water pads around the head. Computer simulations reveal that the high permittivity of water pads results in a strong displacement current that enhances image intensity in the nearby region and alters the intensity distribution of the entire brain. CONCLUSION: The image intensity distribution in the human head at ultra-high field strengths can be effectively manipulated with high permittivity padding. Utilizing this effect, the B(1) field inside the human head of a given RF coil can be adjusted to reduce the B(1) field inhomogeneity artifact associated with the wave behavior (RF passive shimming) or to locally enhance the signal-to-noise ratio (SNR) in targeted regions of interest (ROIs; RF field focusing).

Brain↗
PubMed2006

Open-chest 31P magnetic resonance spectroscopy of mouse heart at 4.7 Tesla.

PURPOSE: To develop a rapid, robust, and accurate method for assessing myocardial energetics in mice and demonstrate its applicability to mouse models of acquired and genetic heart disease. MATERIALS AND METHODS: We combined surface coil localization (10-mm diameter, tunable between (1)H and (31)P, using adiabatic half-passage radiofrequency pulses) and surgery (electrocautery removal of anterior chest wall) to create an open-chest method for acquiring in vivo (31)P nuclear magnetic resonance (NMR) cardiac spectra from mice at 4.7T within 12 minutes. Normal BALB/c mice, BALB/c with myocardial infarction (MI), cardiomyocyte-restricted peroxisome proliferator-activated receptor-delta knockout (KO) (CR-PPARd(-/-)) and control loxP-flanked Ppard (Ppard(flox/flox)) mice were examined. RESULTS: The mean phosphocreatine (PCr)/adenosine triphosphate (ATP) ratios in control BALB/c mice, BALB/c MI mice, Ppard(flox/flox) mice, and PPAR-delta KO mice were 2.13 +/- 0.09 (N = 11), 1.35 +/- 0.07 (N = 9, P < 0.001 vs. BALB/c control), 1.92 +/- 0.09 (N = 5), and 1.31 +/- 0.12 (N = 5, P < 0.005 vs. Ppard(flox/flox) control), respectively. The significant depression of myocardial PCr/ATP we observed in these genetic/acquired models of heart disease was in accord with previous data from analogous large animal models. No NMR signal contamination from chamber blood or adjacent skeletal muscle was identified. CONCLUSION: This new technique provides cardiac (31)P spectra suitable for accurate quantitative analysis in a relatively short acquisition time, is suitable for terminal studies of mouse myocardial energy metabolism, and could be installed in virtually any NMR laboratory to study myocardial energetics in numerous mouse models of human heart disease.

Adenosine Triphosphate↗
PubMed2006

Analysis of paralytic shellfish toxins in Aphanizomenon DC-1 from Lake Dianchi, China.

Lake Dianchi is in Yunnan Province in southwestern China. In recent years, significant cyanobacterial blooms have occurred in this lake nearly every year because of eutrophication. Monitoring data for the past 5 years acquired by our research group showed that phytoplankton composition alternated between species of Microcystis sp. during warm seasons and those of Aphanizomenon sp. during cool seasons. In March 2003, when phytoplankton composition was highly dominated by Aphanizomenon sp., samples were taken from the lake for toxin detection and immediate strain isolation. A mouse bioassay with extracts from the lyophilized field material showed obvious intoxication from paralytic shellfish poisons (PSPs), and all mice died within 30 min. Further analysis of both field and isolated algal strain Aphanizomenon DC-1 by the postcolumn HPLC-FLD method confirmed its PSP-producing ability. The analogues found in the extracts from the field material were neoSTX, dcSTX, and dcGTX3, with contents of 2.279, 1.135, and 0.547 ng/mg DW, respectively. Under laboratory culture condition, toxin content in the Aphanizomenon strain DC-1 varied greatly during different growth phases, with two peaks: in the early-exponential and late-stationary growth phases. When the culture grew at a relatively high rate during the mid- to late-exponential growth phase, toxin content declined gradually. Moreover, the types of toxin in the DC-1 strain varied greatly during a single culture cycle. The HPLC results showed that dcSTX was the only toxin isomer detected throughout the culture period, and its level remained stable. On the other hand, dcGTX2 and GTX4 were the major toxins during the early-exponential and stationary phases, respectively. This article presents the first data on the identification and detection of paralytic shellfish toxins from cyanobacteria in Lake Dianchi. As far as we know, this is also the first report of this type of toxin in inland water bodies in China. Our study indicates the threat associated with PSP toxins in Lake Dianchi and suggests that necessary measures and programs for control are urgently needed to prevent the spread of toxic cyanobacterial blooms.

Animals↗
PubMed2006

Synchronization of Na/K pump molecules by a train of squared pulses.

We experimentally studied the Na/K pump currents evoked by a train of squared pulses whose pulse-duration is about the time course of Na-extrusion at physiological conditions. The magnitude of the measured pump current can be as much as three-fold of that induced by the traditional single pulse measurement. The increase in the pump current is directly dependent on the number of pre-pulses. The larger the number of the pre-pulses is, the higher the current magnitude can be obtained. At a particular number of pre-pulses, the pump current becomes saturated. These results suggest that a large number of pre-pulses may synchronize the pump molecules to work at the same pace. As a result, the pump molecules may extrude Na ions at the same time corresponding to the stimulation pulses, and pump in K ions at the same time during the pulse intervals. Therefore, the measured pump current is three-fold of that measured by a single pulse where the outward and inward pump currents are canceled each other.

Animals↗
PubMed2006

Identification of EGFRvIII-derived CTL epitopes restricted by HLA A0201 for dendritic cell based immunotherapy of gliomas.

The type III variant of the epidermal growth factor receptor (EGFRvIII) mutation is present in 20-25% of patients with glioblastoma multiforme (GBM). EGFRvIII is not expressed in normal tissue and is therefore a suitable candidate antigen for dendritic cell (DC) based immunotherapy of GBM. To identify the antigenic epitope(s) that may serve as targets for EGFRvIII-specific cytotoxic T lymphocytes (CTLs), the peptide sequence of EGFRvIII was screened with two software programs to predict candidate epitopes restricted by the major histocompatibility complex class I subtype HLA-A0201, which is the predominant subtype in most ethnic groups. Three predicted peptides were constructed and loaded to mature human DCs generated from peripheral blood monocytes. Autologous CD8+ T cells were stimulated in vitro with the EGFRvIII peptide-pulsed DCs. One of the three peptides was found to induce EGFRvIII-specific CTLs as demonstrated by IFN-gamma production and cytotoxicity against HLA-A0201+ EGFRvIII transfected U87 glioma cells. These results suggest that vaccination with EGFRvIII peptide-pulsed DCs or adoptive transfer of in vitro elicited EGFRvIII-specific CTLs by EGFRvIII peptide-pulsed DCs are potential approaches to the treatment of glioma patients.

Brain Neoplasms↗
PubMed2006

Pigtail catheters vs large-bore chest tubes for management of secondary spontaneous pneumothoraces in adults.

It is still uncertain if large-bore chest tubes (20F-28F) is superior to pigtail catheter (10F-14F) in terms of the management of secondary spontaneous pneumothoraces (SSP). This study was designed to compare the efficacy and safety associated with placement of large-bore chest tubes vs pigtail catheters in adults experiencing the first episode of SSP. We conducted a retrospective chart review of 91 patients experiencing the first episode of SSP in a university hospital over a 3.5-year period who received treatment by either a large-bore chest tube or a pigtail catheter. Any patient who was younger than 18 years or experiencing mechanical ventilation-related barotraumas or pyopneumothorax was excluded from this study. Various parameters including demographical characteristics, size of pneumothorax, complications, time of pigtail or chest tube extubation, and length of hospital stay were collected and analyzed. Among the enrolled 91 patients, including 76 (83.5%) men with a mean age of 60 +/- 19 years, 69 were initially treated with a pigtail, and 22 patients received conventional chest tubes. Fifty patients (72.5%) undergoing the pigtail drainage and 16 (72.7%) undergoing large-bore chest tube treatment of SSP were successfully treated (P = .88). In addition, there was no significant difference in terms of length of hospital stay, extubation time, recurrence rate, and complication. Pigtail catheters offer a safe and effective alternative for large-bore chest tubes to adult patients experiencing the first episode of SSP, and we strongly suggested that pigtail tube drainage should be considered as the initial treatment of choice.

Adolescent↗
PubMed2006

Association of symptoms of depression and obesity with hypertension: the Bogalusa Heart Study.

BACKGROUND: There is growing evidence that symptoms of depression influence the development of cardiovascular disease. The objective of this study was to evaluate the direct and indirect relationships between symptoms of depression, body mass index (BMI), and hypertension in a biracial (African American-white) rural population. METHODS: This is a cross-sectional study with 1017 study participants (aged 12 to 62 years, 60% white, and 52% women) from 561 families of the Bogalusa Heart Study. A two-stage modeling approach was used to evaluate the relationship between symptoms of depression, BMI, and hypertension. Generalized estimating equation methods (GEE) were used to account for within family correlations. Adjusted coefficients (95% confidence interval [CI]) and odds ratios (OR) were used to explore relationships. RESULTS: Mean (+/- SE) BMI of the study population was 28 (+/-7). Thirty-two percent of those studied had presumptive depression and 13.4% had hypertension. The indirect effect of a 5 unit higher symptoms of depression score was associated with a 14% (OR: 1.14; 95% CI: 1.01-1.28; P < .02) higher likelihood of being hypertensive due to presence of a higher level of BMI in both whites and African Americans. The direct effect of a 5 unit higher symptoms of depression score was found to be nonsignificant (OR: 1.05; 95% CI: 0.92-1.20; P < .22) in whites and significant (OR: 0.81; 95% CI: 0.68-0.95; P < .004) in African Americans. CONCLUSIONS: The presence of a significant indirect effect of symptoms of depression (mediated through higher level of BMI) in both whites and African Americans suggests that BMI can be an intermediate variable linking symptoms of depression and hypertension.

Adolescent↗
PubMed2006

Dendritic cells pulsed or fused with AML cellular antigen provide comparable in vivo antitumor protective responses.

OBJECTIVE: To investigate whether syngeneic BM-derived DCs generated in vitro and fused with syngeneic C1498 tumor cells (murine AML line) could induce a better antitumor protective effect compared to similarly generated DCs pulsed with C1498 lysate with or without co-injection of a class B CpG oligodeoxynucleotide (CpG 7909) in vivo. METHODS: DCs were pulsed with C1498 lysate prior to intravenous administration 14 and 7 days prior to tumor challenge. Separate cohorts received DCs electrically fused to irradiated C1498 cells. Cohorts were administered DCs that were lysate-pulsed or fused with tumor cells on days 14 and 7 prior to tumor injection. Some cohorts were co-injected with CpG 7909 at the time of DC administration. RESULTS: All DC vaccines significantly improved survival (p < 0.01) vs nonvaccinated controls. There was no difference in the antitumor protective response between mice that received pulsed vs fused DCs (47% vs 45% survival). Both DC vaccines generated a fivefold increase in splenic tumor-reactive cytotoxic T-lymphocyte precursor cells and significantly (p < 0.05) higher mean frequencies of IFN-gamma-producing splenocytes compared to controls. CpG 7909 improved the survival of mice receiving the fused DCs (p < 0.05) but not the pulsed DCs. Surviving mice were rechallenged and found to be resistant to lethal tumor injection. CONCLUSIONS: DC vaccine strategies may be effective in generating anti-AML responses. No advantage was observed between lysate-pulsed and tumor cell-fused DCs. CpGs may provide an adjuvant effect depending on the type of DC vaccine administered.

Adjuvants, Immunologic↗
PubMed2006

Triapine (3-aminopyridine-2-carboxaldehyde thiosemicarbazone) induces apoptosis in ovarian cancer cells.

OBJECTIVES: Triapine (Vion Pharmaceuticals, New Haven, CT) is a potent ribonucleotide reductase inhibitor which exerts its antineoplastic activity by inhibiting DNA synthesis and repair. The objectives of this study were: (1) to determine whether Triapine has cytotoxic effects on epithelial ovarian cancer (EOC) cells; (2) to characterize the apoptotic cascade induced in response to this agent; and (3) to determine its utility in combination treatment with carboplatin and paclitaxel. METHODS: Five EOC cell lines were treated with tenfold dilutions of Triapine (0.1 to 100 microM) for 24 and 48 hours. Cell viability was determined by the CellTiter 96 AQueous One Solution Cell Proliferation Assay (Promega Corp, Madison, WI) and the morphologic features of apoptosis were observed using Hoechst staining. The apoptotic cascade was characterized by Western blot analyses. RESULTS: All EOC cell lines treated with Triapine showed decreased cell viability in a time- and dose-dependent manner. Hoechst staining revealed nuclear shrinkage and chromatin condensation and fragmentation, which correlated with the occurrence of apoptosis. Western blots demonstrated that Bid activation was one of the initiating signals involved in the cascade. In addition, cleavage of XIAP and down-regulation of Akt were observed. We also demonstrated that Triapine enhances the cytotoxic effects of carboplatin and paclitaxel. CONCLUSIONS: The present findings demonstrate that Triapine induces cell death through the induction of apoptosis. The initial activation of Bid indicates the involvement of the mitochondrial pathway. The demonstration that Triapine is an effective addition to a carboplatin regimen suggests the possibility of a new combination therapy for ovarian cancer.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2006

Polymorphisms of p53 and p21 genes in chronic obstructive pulmonary disease.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is a multifactorial disease influenced by genetic and environmental factors, particularly cigarette smoking. Although cigarette smoke may be directly mutagenic, polymorphisms in the genes controlling acquired somatic mutations may also contribute, at least to some extent, to the observed differing susceptibilities to COPD. To investigate the involvement of genetic polymorphisms of p53 and p21 in the pathogenesis of COPD, the authors performed a case-control study involving 206 subjects with COPD and 210 healthy smokers as control subjects. METHODS: Polymorphisms of p53 and p21 genes were analyzed using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique on genomic DNA isolated from peripheral lymphocytes. The distribution of the p53 and p21 polymorphisms in healthy subjects and COPD patients was examined and compared using the Pearson X2 test. Significance was accepted at P < 0.05. Odds ratios (ORs) and 95% confidence intervals (CIs) of each specific genotype were calculated using logistic regression analysis to quantitatively assess the degree of association observed. RESULTS: The distribution frequencies of genotypes of p53 codon 72 and p21 codon 31 were significantly different between the COPD and the control groups. Higher ORs for COPD were seen for persons with p53 Pro/Pro or Pro/Arg genotypes against Arg/Arg genotype [OR = 2.35, 95% CI 1.27-4.39, P = 0.008], or p21 Arg/Arg and Arg/Ser genotypes against Ser/Ser genotype [OR = 2.07, 95% CI 1.06-4.05, P = 0.033]. CONCLUSIONS: The polymorphisms of p53 and p21 were significantly associated with the occurrence of smoking-related COPD in Taiwan Chinese patients.

Aged↗
PubMed2006

Distribution and metabolic syndrome correlates of plasma C-reactive protein in biracial (black-white) younger adults: the Bogalusa Heart Study.

The association between plasma C-reactive protein (CRP), a marker of systemic inflammation, and the metabolic syndrome is well recognized. However, information is scant regarding the component of metabolic syndrome that is critical in modulating CRP levels in younger adults. This aspect was examined in a biracial (black-white) community-based sample of 1083 younger adults (mean age, 36.1 years; 71% white, 45% male) enrolled in the Bogalusa Heart Study. Plasma CRP along with metabolic syndrome variables were measured. CRP levels showed a significant race (black>white, P=.01) and sex (female>male, P=.0001) differences, and related to measures of obesity (body mass index [BMI], waist circumference, and sagittal diameter), blood pressure (systolic, diastolic, and mean arterial blood pressure), lipoproteins (low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, triglycerides, total cholesterol-high-density lipoprotein cholesterol ratio), glucose homeostasis (insulin, glucose, homeostasis model assessment of insulin resistance), and uric acid, after adjusting for age, race, sex, and cigarette smoking. Furthermore, CRP levels increased with increasing number of metabolic syndrome risk factors, as defined by the National Cholesterol Education Program Adult Treatment Panel III, regardless of race and sex (P for trend<0001). In multivariate analysis, using 3 separate models for different obesity measures, obesity was the major contributor to the explained variance in each model with BMI, waist, and sagittal diameter contributing 17.0%, 13.4%, and 17.1% of the variance, respectively. In contrast, homeostasis model assessment of insulin resistance contributed 1.2%, 0.3%, and 0% to the explained variance in the models with BMI, waist, and sagittal diameter, respectively. In conclusion, CRP levels differ among race and sex groups and correlate to metabolic syndrome variables in younger adults. In addition, these findings strongly suggest that although obesity and insulin resistance are the main underlying features of the metabolic syndrome, the former appears to be the major mediator of CRP levels, which has important health implications.

Adult↗
PubMed2006

Adiponectin and its correlates of cardiovascular risk in young adults: the Bogalusa Heart Study.

Adiponectin, a novel adipocytokine produced exclusively in the adipose tissue, plays a major role in the development of metabolic syndrome, type 2 diabetes mellitus, and related cardiovascular (CV) diseases. However, information is scant regarding the association of adiponectin with measures of CV risk in young adults. This aspect was examined in a biracial (black-white) community-based sample of 1153 individuals (mean age, 36.2 years; 70% white, 43% male) who participated in the Bogalusa Heart Study. Adiponectin levels showed race (white > black, P < .0001) and sex (female > male, P < .0001) differences, and correlated significantly in a beneficial manner to measures of obesity (body mass index, waist circumference, and abdominal height), mean arterial blood pressure, lipoprotein variables (low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triglycerides), measures of glucose homeostasis (insulin, glucose, homeostasis model assessment of insulin resistance [HOMA-IR]), and uric acid, after adjusting for age, race, sex, and cigarette smoking. In multivariate analysis that used either body mass index or abdominal height as a measure of general and visceral adiposity in 2 separate models, HOMA-IR was the major contributor explaining 18.4% and 18.1% of the variance, respectively. There was a significant interaction between abdominal height and HOMA-IR on adiponectin level in that the inverse association between adiponectin and insulin resistance was pronounced at higher level of visceral adiposity. Furthermore, adiponectin levels decreased with increasing number of metabolic syndrome risk factors defined by the National Cholesterol Education Program Adult Treatment Panel III (P for trend <.0001). Moreover, adiponectin levels were low among those with positive parental histories of coronary heart disease (P = .03), hypertension (P = .04), and type 2 diabetes mellitus (P = .01), considered as surrogate measures of risk. These findings, by showing an inverse association of adiponectin with insulin resistance, visceral adiposity, and related metabolic syndrome, and also with positive parental histories of coronary heart disease, hypertension, and type 2 diabetes mellitus, underscore the value of adiponectin in CV and type 2 diabetes mellitus risk assessments in young adults.

Adiponectin↗
PubMed2006

Longitudinal analysis of haplotypes and polymorphisms of the APOA5 and APOC3 genes associated with variation in serum triglyceride levels: the Bogalusa Heart Study.

Polymorphisms in the APOC3 and APOA5 genes, from the APOA1/APOC3/APOA4/APOA5 gene cluster on chromosome 11q23, have been associated with interindividual variation in plasma triglycerides. APOA5 polymorphisms implicated include 2 in the promoter region (-1131 T/C and -3 A/G) and 1 in exon 2 (+56 C/G). APOC3 polymorphisms implicated include 1 (SstI) in the 3' untranslated region and 1 (-2854 G/T) in the APOC3-APOA4 intergenic region. We analyzed the associations of haplotypes and multilocus genotypes of these polymorphisms on longitudinal serum triglyceride profiles in 360 African American and 823 white subjects from the Bogalusa Heart Study. Subjects were examined from 2 to 8 times (mean +/- SD, 5.4 +/- 1.3) between 1973 and 1996, at ages ranging from 4 to 38 years, with 1978 observations in African Americans and 4465 in whites. Serum triglycerides were significantly higher among whites across all ages. Allele frequencies differed significantly between African Americans and whites at all but the APOA5 +56 C/G locus. Linkage disequilibrium among the loci was higher in whites and haplotype diversity lower: 6 haplotypes had estimated frequencies of more than 1% in African Americans, 5 in whites. Individually, all polymorphisms except APOC3 -2854 G/T showed significant associations with triglyceride levels in the full sample. However, genotype models including all 5 loci showed significant triglyceride associations for only 3 (APOC3 SstI, APOA5 -1131 T/C, and APOA5 +56 C/G); significant interactions among them indicated their effects were not independent. Neither APOC3 -2854 G/T nor APOA5 -3 A/G had significant effects when the other 3 loci were in the models. The EM algorithm was used to estimate haplotype frequencies and assign haplotype probabilities to individuals, which is conditional on their genotypes; individuals' haplotype probability vectors were then used as predictors in multilevel mixed models of longitudinal triglyceride profiles. Of haplotypes comprising, in order, APOC3 SstI and -2854 G/T and APOA5 -1131 T/C, -3 A/G, and +56 C/G, 3 were significantly associated with higher triglycerides, even after adjusting for multiple tests: GGTAG (P = .002), GTTAG (P < .0001), and CGCGC (P = .0002). Each GGTAG haplotype carried would be expected to raise triglyceride levels (relative to those of GTTAC homozygotes) by approximately 19 mg/dL, each GTTAG haplotype by approximately 15 mg/dL, and each CGCGC haplotype by approximately 7 mg/dL. Haplotypes comprising the 3 loci implicated by genotype analyses (SstI, -1131 T/C, and +56 C/G) were also tested: haplotypes C_C_C and G_T_G significantly raised triglycerides, even after adjustment for multiple comparisons (P < .002 for both), with each copy of C_C_C expected to raise triglycerides by approximately 7 mg/dL and each copy of G_T_G by approximately 15 mg/dL. Overall, our findings support those of others in associating specific polymorphisms and haplotypes in the APOA1/C3/A4/A5 gene cluster with higher serum triglyceride levels. However, the degree to which polymorphisms in the APOC3 and APOA5 genes may be independently associated with triglyceride levels remains to be determined.

Adolescent↗
PubMed2006

Angiosarcoma with pulmonary metastasis presenting with spontaneous bilateral pneumothorax in an elderly man.

Cutaneous angiosarcoma is a rare and invasive endothelial-derived sarcoma that occurs most frequently in the scalp and facial skin of elderly men. It is frequently accompanied by thin-walled cavitary pulmonary metastasis, and is often obscure on chest radiograph. We report a case of angiosarcoma of the scalp with cystic metastasis to the lung in a 63-year-old man, presenting as recurrent bilateral spontaneous pneumothorax. Lung metastasis was missed at the first episode of pneumothorax because the lung-expanded chest radiograph showed no significant abnormality. Two months later, bilateral pneumothorax recurred, and high-resolution computed tomography revealed multiple cystic, cavitary and nodular lesions. Pulmonary metastasis was confirmed by video-assisted thoracoscopic surgery, and pleurodesis was performed. After the operation, the patient received chemotherapy; no recurrence of pneumothorax was found during 6 months of follow-up. Pneumothorax in the elderly should be differentiated from malignant metastatic lung tumors.

Hemangiosarcoma↗
PubMed2006

Polyvinylamine boronate adhesion to cellulose hydrogel.

The adhesion of polyvinylamine to wet cellulose was significantly enhanced by the presence of pendant phenylboronic acid groups. It is proposed that adhesion results from boronate ester formation with cellulose at pH > 8. Experiments with phenol derivatized polyvinylamine gave low adhesion supporting the fact that the boronate moiety was responsible for strong adhesion to never-dried cellulose surfaces.

Biocompatible Materials↗
PubMed2006

Quantitative profiling of drug-associated proteomic alterations by combined 2-nitrobenzenesulfenyl chloride (NBS) isotope labeling and 2DE/MS identification.

The identification of drug-responsive biomarkers in complex protein mixtures is an important goal of quantitative proteomics. Here, we describe a novel approach for identifying such drug-induced protein alterations, which combines 2-nitrobenzenesulfenyl chloride (NBS) tryptophan labeling with two-dimensional gel electrophoresis (2DE)/mass spectrometry (MS). Lysates from drug-treated and control samples are labeled with light or heavy NBS moiety and separated on a common 2DE gel, and protein alterations are identified by MS through the differential intensity of paired NBS peptide peaks. Using NBS/2DE/MS, we profiled the proteomic alterations induced by tamoxifen (TAM) in the estrogen receptor (ER) positive MCF-7 breast cancer cell line. Of 88 protein spots that significantly changed upon TAM treatment, 44 spots representing 23 distinct protein species were successfully identified with NBS-paired peptides. Of these 23 TAM-altered proteins, 16 (70%) have not been previously associated with TAM or ER activity. We found the NBS labeling procedure to be both technically and biologically reproducible, and the NBS/2DE/MS alterations exhibited good concordance with conventional 2DE differential protein quantitation, with discrepancies largely due to the comigration of distinct proteins in the regular 2DE gels. To validate the NBS/2DE/MS results, we used immunoblotting to confirm GRP78, CK19, and PA2G4 as bona fide TAM-regulated proteins. Furthermore, we demonstrate that PA2G4 expression can serve as a novel prognostic factor for disease-free survival in two independent breast cancer patient cohorts. To our knowledge, this is the first report describing the proteomic changes in breast cancer cells induced by TAM, the most commonly used selective estrogen receptor modulator (SERM). Our results indicate that NBS/2DE/MS may represent a more reliable approach for cellular protein quantitation than conventional 2DE approaches.

Cell Line, Tumor↗
PubMed2006

Sepsis plasma protein profiling with immunodepletion, three-dimensional liquid chromatography tandem mass spectrometry, and spectrum counting.

Sepsis is a systemic, often fatal inflammatory response whose biochemical pathways are not fully understood and with no single biomarker capable of its reliable prediction. Increased interest in protein profiling to reveal fundamental biochemical events as well as disease diagnosis has grown considerably, largely due to advances in mass spectrometry and related front-end technologies. In this study, patients with sepsis and systemic inflammatory response syndrome (SIRS) were examined using plasma protein profiling following immunodepletion treatment to remove the most abundant proteins, serum albumin, transferrin, haptoglobin, anti-trypsin, IgG, and IgA. These proteins cause significant signal suppression, and their removal allows for lower abundance proteins to be examined through improved ion signal. Analyses after immunodepletion were performed using 3-dimensional reverse phase/strong cation exchange/reverse phase liquid chromatography with electrospray ion trap mass spectrometry (3D LC-MS/MS) and spectrum counting for comparative quantitation. The results revealed a major theme in immune system activity, including activation of the complement and coagulation pathways. Additionally, lipid transport may prove to be important in distinguishing sepsis from SIRS. Specifically, significant multi-fold changes were observed in 10 proteins and are now being investigated for the early diagnosis of sepsis.

Biomarkers↗