Biomedical subjects

Larry R Brown

Publications and source records attributed to Larry R Brown.

7 recordsLinked to original sources

PubMed2006

High-sensitivity blood-based detection of breast cancer by multi photon detection diagnostic proteomics.

We have developed several new methods for blood-based cancer detection by diagnostic proteomics. Ultrasensitive methods of immunoassay using multiphoton-detection (IA/MPD) increase sensitivity by 200- to 1,000-fold (1 femtogram/mL). This has allowed the measurement of cancer biomarkers with very low concentrations in blood that could not be measured for full patient cohorts with conventional immunoassays. Sensitivity and specificity in cancer detection have been found to be potentiated by use of immunoassay panels which include tissue-specific cancer biomarkers as well as cytokines and angiogenic factors. The ultrasensitive immunoassays revealed that patient to patient variations in the concentrations of individual biomarkers in blood can extend over many orders of magnitude (up to six) and that the distributions of biomarker concentrations over patient cohorts are non-Gaussian. New methods of data analysis which correlate abundances of multiple, different biomarkers have been developed to deal with such data sets. Sensitivity and specificity of about 95% have been achieved for blood-based detection of breast cancer in pilot studies on 250 patients and 95 controls. Pilot studies indicate that this methodology may also allow differentiation of malignant breast cancer from benign lesions and can provide similar sensitivity and specificity for other epithelial cancers such as prostate cancer, ovarian cancer and melanoma. The methods developed for selection, application, and evaluation of very high sensitivity biomarker panels are expected to have general relevance for diagnostic proteomics.

Adult↗

PubMed2006

Looking for Thom's biomarkers with proteomics.

In recent years, large numbers of putative disease biomarkers have been identified. Combinations of protein biomarkers have been proposed to overcome the lack of single, magic-bullet identifiers of disease conditions. The number of biomarkers in a panel must be kept small to avoid the combinatorial explosion that requires very large, uneconomical sample cohorts for validation. Recent results on high sensitivity blood-based diagnostic proteomics (Godovac-Zimmermann, J et al., J. Proteome Res. 2006) suggest that the keys to identifying useful panels include judicious application of physiological knowledge to choose appropriate combinations of local, tissue/disease markers and global, systemic markers and to use very high sensitivity protein detection. Biomarkers that show non-Gaussian landscapes reminiscent of Rene Thom's multiple, stable-state landscapes seem to have the greatest predictive value for breast cancer (Godovac-Zimmermann, J. et al., J. Proteome Res. 2006).

Biomarkers↗

PubMed2005

Perspectives in spicing up proteomics with splicing.

In the post-genomics era there has been an acceleration of understanding of cellular and organismal biology and this acceleration has moved the goalposts for proteomics. Higher eukaryotes use alternative promoters, alternative splicing, RNA editing and post-translational modification to produce multiple isoforms of proteins from single genes. Switching amongst these isoforms is a major mechanism for control of cellular function. At present fundamental limitations in sensitivity, in absolute quantitation of proteins and in the characterization of protein structure at functionally important levels strongly limit the applicability of proteomics to higher eukaryotes. Recent developments suggest that quantitative, top-down proteomics analyses of complete proteins at sub-attomole levels are necessary for physiologically relevant studies of higher eukaryotes. New proteomics technologies which will ensure the future of proteomics as an important technology in medicine and cellular biology of higher eukaryotes are becoming available.

Alternative Splicing↗

PubMed2005

Proteomics profiling of nuclear proteins for kidney fibroblasts suggests hypoxia, meiosis, and cancer may meet in the nucleus.

Proteomics methods were used to characterize proteins that change their form or abundance in the nucleus of NRK49F rat kidney fibroblasts during prolonged hypoxia (1% O(2), 12 h). Of the 791 proteins that were monitored, about 20% showed detectable changes. The 51 most abundant proteins were identified by mass spectrometry. Changes in nuclear receptor transcription factors (THRalpha1, RORalpha4, HNF4alpha, NUR77), other transcription factors (GATA1, AP-2alpha, OCT1, ATF6alpha, ZFP161, ZNF354A, PDCD2), and transcription cofactors (PC4, PCAF, MTA1, TCEA1, JMY) are indicative of major, co-ordinated changes in transcription. Proteins involved in DNA repair/recombination, ribosomal RNA synthesis, RNA processing, nuclear transport, nuclear organization, protein translation, glycolysis, lipid metabolism, several protein kinases (PKCdelta, MAP3K4, GRK3), as well as proteins with no established functional role were also observed. The observed proteins suggest nuclear regulatory roles for proteins involved in cytosolic processes such as glycolysis and fatty acid metabolism, and roles in overall nuclear structure/organization for proteins previously associated with meiosis and/or spermatogenesis (synaptonemal complex proteins 1 and 2 (SYCP1, SYCP2), meiosis-specific nuclear structural protein 1 (MNS1), LMNC2, zinc finger protein 99 (ZFP99)). Proteins associated with cytoplasmic membrane functions (ACTN4, hyaluronan mediated motility receptor (RHAMM), VLDLR, GRK3) and/or endocytosis (DNM2) were also seen. For 30% of the identified proteins, new isoforms indicative of alternative transcription were detected (e.g., GATA1, ATF6alpha, MTA1, MLH1, MYO1C, UBF, SYCP2, EIF3S10, MAP3K4, ZFP99). Comparison with proteins involved in cell death, cancer, and testis/meiosis/spermatogenesis suggests commonalities, which may reflect fundamental mechanisms for down-regulation of cellular function.

Animals↗

PubMed2005

Commercial challenges of protein drug delivery.

The discovery of insulin in 1922 marked the beginning of research and development to improve the means of delivering protein therapeutics to patients. From that period forward, investigators have contemplated every possible route of delivery. Their research efforts have followed two basic pathways: one path has focused on non-invasive means of delivering proteins to the body; and the second path has been primarily aimed at increasing the biological half-life of the therapeutic molecules. Thus far, the commercial successes of protein delivery by the nasal, oral and pulmonary routes have been more opportunistic rather than the application of platform technologies applicable to every protein or peptide. In several limited cases, sustained delivery of peptides and proteins has employed the use of polymeric carriers. More successes have been achieved by chemical modification using amino acid substitutions, protein pegylation or glycosylation to improve the pharmacodynamic properties of certain macromolecules. Today, commercial successes for protein and peptide delivery systems remain limited. The needle and syringe remain the primary means of protein delivery. Major hurdles remain in order to overcome the combined natural barriers of drug permeability, drug stability, pharmacokinetics and pharmacodynamics of protein therapeutics.

Animals↗

PubMed2003

Proteomics approaches to elucidation of signal transduction pathways.

Recent applications have shown that proteomics can provide crucial new information regarding cellular signaling processes. Bottom-up and small-scale top-down proteomics approaches related to routine biochemical methods have become widely applied to identify new aspects of established signaling pathways. Top-down, global proteomics methods are developing rapidly and are beginning to deliver information on global integration of signaling processes that has been difficult to obtain with conventional approaches.

ErbB Receptors↗

PubMedDate not supplied

Ultra-sensitive immunoassays using multi-photon-detection in diagnostic proteomics of blood.

Multiphoton-detection methods that detect as little as 1000 atoms of (125)I-streptavidin increase the sensitivity of immunoassays by 200- to 1000-fold (1 femtogram/mL). Improved background suppression allows 20- to 100-fold improvements in sensitivity for conventional immunoassays (10-50 femtogram/mL). Quantitation of low abundance biomarkers in blood (PSA, TNFalpha, VEGF, IL-1beta, IL-6, and IL-8), for the first time for complete patient cohorts, indicates that very high analytical sensitivity and new statistical methods are crucial for serum-based diagnostic proteomics.

Adult↗