Perfect Positive Correlation Research Articles

The Combined and Relative Effect of Economic , Youth Nature and Society on Premarital Sexual Activities among Youth in Ikenne Local Government , Ogun State Nigeria

The study examines the combined and relative effects of Economic, Nature and Society on Premarital sex. It made use of simple random technique in selecting 250 youths within Ikenne local government in Ogun State, Nigerian. The age range of the respondents was between 15 to 35 years with the mean age of 24.5 and standard deviation of 3.291. The ex-post-facto research design was employed. A 35 item; Youth Attitude towards Sexual Practices (YATSP) developed by the Researcher was used to generate data for the study. All the hypotheses data were tested at 0.05 level of significance. Data analysis involved the use of multiple regressions (backward), ANOVA and Pearson product moment Correlation. The result indicated in model 3, that the predictors' variables accounted for 56.4% percent of the variation in premarital sexual activities. Each of the independent variables contributes significantly to the Premarital Sexual activities and a perfect positive correlation existed between Premarital Sexual activities and the three independent variables. Suggestions were made based on the outcome.

English

  Lead, with its toxic emission and pollution, is one of the hazardous chemical components of electronic wastes (e-wastes) rapidly generated in developing countries. This study assessed the environmental health effects of crude lead extracted from e-wastes materials, as determined by its acute toxicity (rat, oral). Diluted HNO3 and hot concentrated HCl tests were used to confirm the presence of lead in the extract. LD50 (400 mg/kg) showed higher toxicity than the lowest toxic dose of 790 mg/kg reported in literature. There was a perfect positive correlation between the log dose and dead percentage, which was significant at 0.014, with 0.99° of confidence. The R2 (0.839) and significance F (0.029) showed high reliability. In view of this, we recommend the inclusion of enlightenment and making/enforcing adequate policies for improved management and control of e-waste materials. Key words: Environmental health effect, toxic chemical component, e-waste

Impact of Withdrawal Time on Adenoma Detection Rates: Analysis of Average Risk Screening Colonoscopy Examinations

Purpose: In average risk individuals undergoing screening colonoscopy, withdrawal time of at least six minutes or more in normal exams is considered as a quality indicator. However, data is conflicting on the correlation of withdrawal time and detection of adenomas. The aim of this study is to estimate the impact of withdrawal time on detection of adenomas and polyps. Methods: Retrospective analysis of average risk screening colonoscopies performed at a university hospital using the electronic reporting system was done. All patients who underwent a colonoscopy with the indication “screening-average risk” during the study period [2006-2011] were included. Surveillance procedures and patients with high risk family history were excluded since they are expected to have higher adenoma rate. We reviewed demographic details, procedural data and corresponding pathology reports. Polyp detection rate (PDR) is defined as the number of colonoscopies with at least one polyp removed/total number of procedures. Adenoma detection rate (ADR) is defined as the number of colonoscopies with removal of at least one pathologically confirmed adenoma/total number of procedures. Withdrawal time is defined as the time spent withdrawing from cecum to anus. Colonoscopies where polyps or malignancies were found were excluded, and only normal colonoscopies were included to calculate the mean withdrawal time for each endoscopist. Spearman Rank Correlation coefficient was calculated to estimate the degree of correlation between the withdrawal time and ADR/PDR. Results: A total of 2370 patients fulfilled the inclusion criteria. ADR, PDR, and mean withdrawal times for each of the participating endoscopists were calculated (see Table). The spearman rank correlation coefficient (S) for withdrawal time and ADR was 1.0 [P=0.016] confirming a perfect positive correlation between withdrawal time and ADR. The S coefficient for withdrawal time and PDR was 0.9, [P=0.083].Table: No Caption available.Conclusion: This study confirms that a longer duration of withdrawal time during screening colonoscopy improves adenoma detection rate.

A reduction in between subject variability is not mandatory for selecting a new covariate

Population pharmacokinetic-pharmacodynamic analysis involves nonlinear hierarchical modelling where the mean response in a population and the variability in response from different sources are studied. It generally consists of two model hierarchies: a model for residual error and a model for heterogeneity termed between subject variance (BSV). The overall variability in a parameter within a population termed population parameter variance (PPV) consists of within subject variance (WSV) and BSV. Both these variances can further be split into random and predictable components. The predictable component of BSV (termed BSVP) is explained by covariates, individual characteristics e.g. weight. As BSVP increases, the remaining unpredictable (or random) between subject variability (BSVR) decreases since BSV = BSVP + BSVR, and BSV is a constant in any given data set. Since BSV and BSVR are estimated from the base and full covariate models, respectively, then BSVP = BSV-BSVR. The aim of this study was to explore the hypothesis, that a significant covariate may not always decrease BSVR. The specific aims were: (1) to explore circumstances where BSVR may not be reduced when adding a significantly correlated covariate and (2) to explore whether specific models for covariates may eliminate this anomaly when assessing BSVR. Simulations were performed using MATLAB (2011a) and estimation using NONMEM (ver 7.2) with FOCE and INTERACTION. A 1-compartment intravenous bolus PK model was used for simulation following a single unit dose (d = 1). The BSV of clearance [BSV(CL)] was described according to a log-normal distribution model with mean zero and variance ω². An additive random unexplained variability was assumed. Initially, we show through a simple simulation that BSVR can increase when a significantly correlated covariate is added to the model. We follow this with five simulation scenarios, A to E, that have various levels of correlation between the continuous covariate (Z) and CL ranging from 0 to 100 %. Each simulated scenario was replicated 100 times and estimated by a base model (i.e. without covariate addition) and six covariate models (M1-M6) which included non-nested (M1), nested (M2), and two types of interaction models for each of M1 and M2; non-nested interaction (M3, M5), nested interaction (M4, M6). Initially, through a motivating example we show that BSVR may not reduce even when there is 50 % correlation between the covariate Z and CL. It was found that with 0 % correlation M1, the non-nested covariate model (NNCM) resulted in negative BSVP (inflated BSVR) whereas M2, the nested covariate model (NCM), resulted in a calculated BSVP of zero. NNCM (M1) shows negative BSVP (BSVR > BSV) with correlation as high as 50 % and this model needs a minimum of 75 % correlation to show a positive BSVP. NCM (M2) shows positive but downwardly biased BSVP with 25, 50 and 75 % correlations. However, inclusion of a covariate-eta interaction term for both types of covariate models resulted in greater BSVP for 25, 50 and 75 % correlation scenarios compared to NNCM and NCM respectively. For 100 % correlation, it was found that covariate-eta interaction models show the same BSVP as the models without the interaction term, i.e. under perfect positive correlation all models perform similarly and correctly. It was found that a significantly correlated covariate may not reduce BSVR and in fact it may inflate the BSVR due to statistical misspecification of the covariate model. Incorporating statistical models that account for the covariate-eta interaction may be useful diagnostically in identifying the variability explained by covariates.

Validation of a formula for predicting daily CD34+ cell collection by leukapheresis

The ability to predict how many CD34(+) cells a donor will collect on a given day is vital for efficient leukapheresis. We validated a formula to predict daily CD34(+) cell collections by leukapheresis, calculated as follows: (peripheral blood CD34(+) cells/L) × (adjusted collection efficiency of 30%)/body weight (kg), multiplied by the number of liters processed. This validation was performed from 234 donors undergoing 30 L large volume leukapheresis (LVL) and 162 donors undergoing smaller collections (non-LVL). The LVL group consisted of 811 collection events (625 multiple myeloma, 186 non-myeloma). The non-LVL group consisted of 224 collection events (196 multiple myeloma, 28 non-myeloma). All predicted and observed CD34(+) cell collection numbers were plotted (predicted versus observed) and assessed using linear regression analyses. Linear correlation coefficients (r-values), slopes and intercepts of the regression lines were evaluated. Predicted versus observed data points across all quantities of CD34(+) cells/kg collected by both LVL and non-LVL had strong r-values of 0.947 and 0.913, respectively, demonstrating near perfect positive linear correlations. Data for LVL collections subgrouped by number of cells collected (poor, intermediate and good), mobilization regimen, collection day and diagnosis were analyzed the same way and showed consistent findings. We have validated a formula with a strong ability to predict collection of CD34(+) cells/kg that would allow for individualization of collection for any donor once the peripheral blood CD34(+) cell count and optimal goal of collection were known; to date this has not been published by other groups.

Linking reputations through umbrella branding

This paper develops a theory of umbrella branding as a way to link the reputations of otherwise unrelated products. The analysis predicts that umbrella branding can credibly signal positive correlation between the qualities of the included products to consumers, but cannot certify high quality or signal negative quality correlation. Moreover, whenever umbrella branding signals perfect positive quality correlation, firms that already sell a high (low) quality product have stronger (weaker) incentives to invest in developing another high quality product than new entrants.

Multidimensional Product Differentiation with Discrete Characteristics

In this paper we consider a duopoly model of multidimensional vertical product differentiation where product features are discrete and consumers' tastes are described by a joint density function that belongs to the class of Elliptically Contoured Distributions. We prove that in any equilibrium one firm always includes all characteristics in the product. Moreover, when types have perfect positive correlation the unique equilibrium involves maximum differentiation. More importantly, the main result states that the other firm's equilibrium level of differentiation is determined by the correlation among types.

Independency Or Correlation? The GCC Stock Markets, Interest Rates, And Oil Prices: Against All Financial Rules

This paper examines the relationship(s) that exist among the four GCC stock markets: Kuwait, Saudi, UAE, and Oman. We observed and measured how and up to which extent oil prices, gold prices, and US interest rates affect these markets for the period 2005. We noticed a positive relationship between these markets and each factor and a perfect positive correlation between the Kuwaiti and Saudi markets.

A case of hydrated lime (Caoh) 2 toxicity in Clarias gariepinus juveniles

A sudden increase in mortality was observed in a fish pond stocked with 1034 6-weeks old Clarias juveniles, after exhibiting various forms of nervous disorders such as severe irritation and erratic convulsive swimming habits. A total of 165 mortality, with mean of 20.6 ± 14.8/day were recorded within the first week of stocking. A perfect positive correlation of water level in the pond R 2 = 0.92, with inverse mortality R 2 = 0.14 and pH values R 2 = 0.78 within the first 8 days were recorded. Carcasses exhibited various forms of skin discoloration, petechial and ecchymotic hemorrhages were observed on the cranium, base of the fins, body sides and bloated belly. Many carcasses had eroded body mucous, manifested by various forms of grayish bands of skin lesion. Mean optimal values for nitrate (0,mg/litre), nitrite (0.1,mg/litre) and ammonia (0.1mg/litre) in the water were recorded using commercial multiple water testing kit, although declining pH value of 11 to 7.5 was observed within the period. Another set of 200 Clarias juveniles of the same batch was raised in an adjacent pond, and appeared clinically healthy. Spontaneous recovery was observed upon transfer of the whole juveniles to a new pond of fresh water, with mean pH 7.5 and treated with oxytetracycline and vitaminmineral supplements. Diagnosis of acute lime toxicity was made. Normal growth was restored but, evidence of necrotic skin discoloration was retained to adulthood in 20% of the fishes.

Visceral-Locomotory Pistoning in Crawling Caterpillars

Animals with an open coelom do not fully constrain internal tissues, and changes in tissue or organ position during body movements cannot be readily discerned from outside of the body. This complicates modeling of soft-bodied locomotion, because it obscures potentially important changes in the center of mass as a result of internal tissue movements. We used phase-contrast synchrotron X-ray imaging and transmission light microscopy to directly visualize internal soft-tissue movements in freely crawling caterpillars. Here we report a novel visceral-locomotory piston in crawling Manduca sexta larvae, in which the gut slides forward in advance of surrounding tissues. The initiation of gut sliding is synchronous with the start of the terminal prolegs' swing phase, suggesting that the animal's center of mass advances forward during the midabdominal prolegs' stance phase and is therefore decoupled from visible translations of the body. Based on synchrotron X-ray data and transmission light microscopy results, we present evidence for a two-body mechanical system with a nonlinear elastic gut that changes size and translates between the anterior and posterior of the animal. The proposed two-body system--the container and the contained--is unlike any form of legged locomotion previously reported and represents a new feature in our emerging understanding of crawling.

Assessment of yield stability in sorghum

Sorghum (Sorghum bicolor L. (Moench)) is the third major cereal crop in Ethiopia in terms of area and production next to tef (Eragrostis tef) and maize (Zea mays). It is the major crop in drought stressed lowland areas that cover 66% of the total arable land in the country. Yield stability is one of the setbacks facing plant breeders in developing widely adapted varieties with superior yield. The present study was carried out to investigate the effect of genotype by environment (GxE) on the yield stability of sorghum (Sorghum bicolor) using fifteengenotypes in eight environments (Locations x years combination). There were significant differences among the genotypes, the environments and GxE interactions. Thus, the three types of univariate stability models: Type-1 (CVi and S2i), Type-2 (W2i, s2i, and bi) and Type-3 (Sd2i) were compared for ranking of the genotypes. Theparameters of W2i and si2 had perfect positive correlation (r=1.0) and strong positive correlation with bi (r=0.80),but either weak or no correlation with the rest of the parameters. Similarly, CVi and S2i had strong rank correlation(r=0.97) but both had either very weak or no rank correlation with the rest of the parameters tested. The Sd2i had very weak negative correlation with the remaining parameters. Based on the three stability statistics, the different genotypes were classified as stable. To compliment and verify findings of this univariate approach, the GxE which uses a mulivariate approach was used. The multivariate approach (AMMI model) gives a broader inference. Based on the AMMI model, genotypes 2 and 5 were the most stable, although genotypes 1 and 3 had satisfactory levels of yield performance as well as stability. Therefore, these four genotypes with wider adaptationare recommended for sorghum growing dry lowlands of the country.

Legal Ages for Purchase and Consumption of Alcohol and Heavy Drinking Among College Students in Canada, Europe, and the United States

ABSTRACT Heavy drinking and associated negative consequences remain a serious problem among college students. In a secondary analysis of data from two published study, the authors examine the correlation between minimum legal age to purchase and/or consume alcohol and rates of heavy drinking among college students in 22 countries. The published studies use identical definitions of heavy drinking and similar methodologies. In the study of 20 European countries and the United States, there is a positive correlation between prevalence of heavy drinking and both minimum legal purchase age (r =.34) and minimum legal drinking age (r =.19); in the study of Canada and the United States, there is a perfect positive correlation (r = 1.0). Examination of this evidence does not support the conclusion that a lower minimum legal age for purchase and/or consumption of alcoholic beverages is a protective factor for decreasing heavy drinking among college students.

HMGA2 Maintains Oncogenic RAS-Induced Epithelial-Mesenchymal Transition in Human Pancreatic Cancer Cells

Pancreatic cancer is a highly aggressive malignancy due to elevated mitotic activities and epithelial-mesenchymal transition (EMT). Oncogenic RAS and transforming growth factor-beta signaling are implicated in these malignant features. The mechanisms that underlie EMT need to be addressed since it promotes tissue invasion and metastasis. The high-mobility group A protein 2 (HMGA2) is a non-histone chromatin factor that is primarily expressed in undifferentiated tissues and tumors of mesenchymal origin. However, its role in EMT in pancreatic cancer is largely unknown. Here we report that HMGA2 is involved in EMT maintenance in human pancreatic cancer cells. Specific knockdown of HMGA2 inhibited cell proliferation, leading to an epithelial-state transition that restores cell-cell contact due to E-cadherin up-regulation. Consistently, an inverse correlation between HMGA2-positive cells and E-cadherin-positive cells was found in cancer tissues. Inhibition of the RAS/MEK pathway also induced an epithelial transition, together with HMGA2 down-regulation. Transcriptional repressors of the E-cadherin gene, such as SNAIL, decreased after HMGA2 knockdown since HMGA2 directly activated the SNAlL gene promoter. The decrease of SNAIL after RAS/MEK inhibition was suppressed by HMGA2 overexpression. Further, let-7 microRNA-mediated HMGA2 down-regulation had no effect on the prevention of the transformed phenotype in these cells. These data shed light on the importance of HMGA2 in reversibly maintaining EMT, suggesting that HMGA2 is a potential therapeutic target for the treatment of pancreatic cancer.

Expressão da aromatase em carcinomas de mama ductais invasivo e in situ presentes na mesma mama

to evaluate the expression of aromatase in simultaneously invasive ductal carcinoma (IDC) and ductal carcinoma in situ (DCIS). forty-five surgical samples were obtained from mastectomy and quadrantectomy with simultaneous IDC and DCIS of stage I and II patients. Aromatase was evaluated using antibodies anti-aromatase and the samples classified in accordance with the number and intensity of stained cells. Aromatase was expressed positively in 32(71%) and negatively in 13(29%) of the cases in the IDC. The same results were obtained in the DCIS showing a perfect positive correlation. In the normal epithelium,aromatase was positive in 19(42.2%) and negative in 26 (57.8%) and a positive correlation, statistically significant was obtained when compared with IDC and DCIS(p<0.01). Concerning the normal stroma, positivity was only 7 (15.5%) showing no correlation with aromatase expression. Aromatase was positive in 36(80%) of the tumor stroma and this result was statistically significant as in the IDC and DCIS. Comparing results of aromatase expression with nuclear grade, histological grade, tumor size and age no difference was found. our results demonstrated high correlation between aromatase expression in IDC, DCIS, normal epithelium and tumor stroma showing a possible autocrine and paracrine mechanism of this enzyme in breast cancer.

Traffic-Related Air Pollution in Relation to Incidence and Prognosis of Coronary Heart Disease

Long-term air pollution exposure is associated with increased mortality, but the association with incidence of fatal and nonfatal coronary heart disease is less certain. Moreover, it is unknown how chronic exposure to air pollution affects prognosis among survivors of a first coronary event. This study evaluated the association between long-term traffic-related air pollution exposure and incidence of nonfatal and fatal coronary events, as well as subsequent hospital readmission and mortality among myocardial infarction survivors. The study population comprised all residents of Rome aged 35-84 years during the period 1998-2000. Residential nitrogen dioxide (NO2) exposure as a marker of traffic pollution was assessed by a land-use regression model in 1995-1996 (R = 0.69). A total of 11,167 incident coronary events were observed (4654 fatal, including 3598 out-of-hospital coronary deaths, and 6513 nonfatal). The cohort of 6513 survivors was followed 4.0-7.5 years for readmission or mortality, starting 28 days from the date of first event. Relative risks per 10 mug/m of NO2 exposure, adjusted for age, sex, and socioeconomic status, were calculated by Poisson regression (population-based incidence) and Cox regression (cohort analysis). The relative risk for incidence in coronary events per 10 mug/m of NO2 was 1.03 (95% confidence interval = 1.00-1.07). Stronger associations were found for fatal cases (1.07; 1.02-1.12) and out-of-hospital deaths (1.08; 1.02-1.13). Using NO2 exposure at the time of the first event, there was no association of air pollution exposure with either subsequent hospital readmission or mortality among survivors of the first coronary event. Long-term air pollution exposure increases the risk of coronary heart disease, particularly fatal events. Hospital readmission or subsequent mortality among survivors was not associated with traffic air pollution.

Brittleness index of machinable dental materials and its relation to the marginal chipping factor

Objectives The machinability of a material can be measured with the calculation of its brittleness index (BI). It is possible that different materials with different BI could produce restorations with varied marginal integrity. The degree of marginal chipping of a milled restoration can be estimated by the calculation of the marginal chipping factor (CF). The aim of this study is to investigate any possible correlation between the BI of machinable dental materials and the CF of the final restorations. Methods The CEREC™ system was used to mill a wide range of materials used with that system; namely the Paradigm MZ100™ (3M/ESPE), Vita Mark II (VITA), ProCAD (Ivoclar-Vivadent) and IPS e.max CAD (Ivoclar-Vivadent). A Vickers Hardness Tester was used for the calculation of BI, while for the calculation of CF the percentage of marginal chipping of crowns prepared with bevelled marginal angulations was estimated. Results The results of this study showed that Paradigm MZ100 had the lowest BI and CF, while IPS e.max CAD demonstrated the highest BI and CF. Vita Mark II and ProCAD had similar BI and CF and were lying between the above materials. Statistical analysis of the results showed that there is a perfect positive correlation between BI and CF for all the materials. Conclusions The BI and CF could be both regarded as indicators of a material's machinability. Within the limitations of this study it was shown that as the BI increases so does the potential for marginal chipping, indicating that the BI of a material can be used as a predictor of the CF.

Contaminant degradation in physically and chemically heterogeneous aquifers

This paper examines the importance of the correlation between hydraulic conductivity ( K) and degradation rate constant ( k) during the transport of reactive contaminants in heterogeneous aquifers. We simulated reactive transport in an ensemble of two-dimensional heterogeneous aquifers. Two sets of transport simulations were conducted: one in which a perfect positive correlation was assumed between ln( K) and ln( k), and one in which a perfect negative correlation was assumed. We found that the sign of the correlation has important consequences for the contaminant transport. Qualitatively, a negative correlation leads to significantly more pronounced “fingering” of the contaminant plume than does a positive correlation, with potentially important consequences for downgradient receptors. Quantitatively, the expected behavior (as quantified by the contaminant mass remaining in the aquifer) is statistically different between the positive and negative cases: on average, more contaminant mass persists when K and k are negatively correlated. Also, the negative correlation leads to more variability between realizations of the ensemble, whereas a positive correlation induces relatively little variability between realizations. We discuss the implications of these findings for the management of contaminated aquifers.

Evaluation of Stability of k-Means Cluster Ensembles with Respect to Random Initialization

Many clustering algorithms, including cluster ensembles, rely on a random component. Stability of the results across different runs is considered to be an asset of the algorithm. The cluster ensembles considered here are based on k-means clusterers. Each clusterer is assigned a random target number of clusters, k and is started from a random initialization. Here, we use 10 artificial and 10 real data sets to study ensemble stability with respect to random k, and random initialization. The data sets were chosen to have a small number of clusters (two to seven) and a moderate number of data points (up to a few hundred). Pairwise stability is defined as the adjusted Rand index between pairs of clusterers in the ensemble, averaged across all pairs. Nonpairwise stability is defined as the entropy of the consensus matrix of the ensemble. An experimental comparison with the stability of the standard k-means algorithm was carried out for k from 2 to 20. The results revealed that ensembles are generally more stable, markedly so for larger k. To establish whether stability can serve as a cluster validity index, we first looked at the relationship between stability and accuracy with respect to the number of clusters, k. We found that such a relationship strongly depends on the data set, varying from almost perfect positive correlation (0.97, for the glass data) to almost perfect negative correlation (-0.93, for the crabs data). We propose a new combined stability index to be the sum of the pairwise individual and ensemble stabilities. This index was found to correlate better with the ensemble accuracy. Following the hypothesis that a point of stability of a clustering algorithm corresponds to a structure found in the data, we used the stability measures to pick the number of clusters. The combined stability index gave best results.

Screening for type 2 diabetes mellitus using gingival crevicular blood

This study was conducted to assess the usefulness of the gingival crevicular blood for estimating the glucose level during routine periodontal examination using Xitux Diagnostics Smart-X self-monitoring blood glucose device among Jordanian patients attending dental teaching clinics. A total of 34 type 2 diabetic patients (18 males and 16 females) and 26 non-diabetic patients (14 males and 12 females) participated in this study. Glucose level was measured in a sample of gingival crevicular blood and in another sample obtained by finger puncture using a self-monitoring device. Glucose measurements from gingival crevicular blood samples, ranged from 57 to 250 mg dl-1 with a mean of 125.4+/-60.7 mg dl-1 (+/-SD) and glucose measurements obtained by finger puncture, ranged from 62 to 263 mg dl-1 with a mean of 131.9+/-61.1 mg dl-1. Pearson's correlation coefficient was performed to assess the correlation between the glucose measurements in these two samples. Pearson's correlation coefficient showed an almost perfect positive correlation between the gingival readings and finger-puncture readings (r=0.997, P<0.0001). In conclusion, gingival crevicular blood can provide an acceptable source for measuring blood glucose level. However, the technique to obtain an acceptable blood sample from gingival crevices is not always feasible which would limit its application as a clinical practice. Additional studies that refine this technique and use larger sample size are recommended.

Correlation of Relative Abundance Ratios Derived from Peptide Ion Chromatograms and Spectrum Counting for Quantitative Proteomic Analysis Using Stable Isotope Labeling

In this study, S. cerevisiae crude membrane fractions were prepared using the acid-labile detergent RapiGest from cells grown under rich and minimal media conditions using 14N and 15N ammonium sulfate as the sole nitrogen source. Four independent MudPIT analyses of 1:1 mixtures of sample were prepared and analyzed via quantitative multidimensional protein identification technology on a two-dimensional ion trap mass spectrometer. Using the method described in this study, low-abundance integral membrane proteins with up to 14 transmembrane domains were identified and their protein expression determined when sufficient spectrum counting and ion chromatogram information was generated. We demonstrate that spectrum counting and mass spectrometry derived ion chromatograms strongly correlate for determining quantitative changes in protein expression. Spectrum counting proved more reproducible and has a wider dynamic range contributing to the deviation of the two quantitative approaches from a perfect positive correlation.