Biomedical subjects

David Geho

Publications and source records attributed to David Geho.

7 recordsLinked to original sources

PubMed2006

Accurate diagnosis of acute graft-versus-host disease using serum proteomic pattern analysis.

OBJECTIVE: The rapid diagnosis of acute graft-versus-host disease (GVHD) following allogeneic hematopoietic cell transplantation (HCT) is important for optimizing the management of this life-threatening complication. Current diagnostic techniques are time-consuming and require invasive tissue sampling. We investigated serum protein pattern analysis using surface-enhanced laser desorption ionization time-of-flight (SELDI-TOF) mass spectrometry as a tool to diagnose GVHD. PATIENTS AND METHODS: Eighty-eight serum samples were obtained from 34 patients undergoing HCT either pretransplant (n = 28 samples) or at various time points posttransplant (n = 60 samples), including 22 samples obtained on the day of onset of acute GVHD symptoms. Serum proteomic spectra generated from a "training set" of known samples were used to identify distinct proteomic patterns that best categorized a sample as either pretransplant, posttransplant non-GVHD, or GVHD; these distinct proteomic signatures were subsequently used to classify samples from a masked "test" sample set into the appropriate diagnostic category. RESULTS: Proteomic pattern analysis accurately distinguished GVHD samples from both posttransplant non-GVHD samples and pretransplant samples (100% specificity and 100% sensitivity in both cases). Furthermore, distinct serum proteomic signatures were identified that distinguished pretransplant from posttransplant non-GVHD samples (100% specificity and 94% sensitivity). CONCLUSION: These preliminary data suggest a potential application of SELDI-TOF-based proteomic analysis as a rapid and accurate method to diagnose acute GVHD.

Adult↗

PubMed2006

Intestinal disease in Hermansky-Pudlak syndrome: occurrence of colitis and relation to genotype.

BACKGROUND & AIMS: Hermansky-Pudlak syndrome (HPS), a rare autosomal recessive disorder characterized by oculocutaneous albinism and platelet dysfunction, results from mutations in 1 of at least 7 different genes. Some patients develop a fatal pulmonary fibrosis and others a disabling colitis. This study aimed to document the occurrence of colitis among HPS patients, characterize gastrointestinal tract involvement in HPS, and analyze the distribution of colitis among HPS genotypes. METHODS: Of the 122 HPS patients followed at the National Institutes of Health Clinical Center between 1993 and 2005, 24 were evaluated by endoscopy for gastrointestinal complaints. The histology of gastrointestinal biopsies was retrospectively examined to assess for inflammatory changes, granulomata, and pigmented macrophages. These data were compared with symptoms and HPS genetic subtypes. RESULTS: At colonoscopy, 7 of 23 patients (30%) had endoscopic mucosal abnormalities, including nodularity, erythema, petechiae, or erosions. Six of these 7 patients (86%) had findings of colitis on biopsy. Of the 16 patients with normal-appearing colonic mucosa, 2 patients (12%) had colitis on biopsy. Pigmented macrophages were also observed in the colonic lamina propria in 16 of the 23 patients (70%). Of the 8 patients with confirmed colitis, 7 had the HPS-1 subtype, and 1 had the HPS-4 subtype. CONCLUSIONS: There is an increased frequency of colitis in our population of 122 HPS patients (8/122, 7%) and in HPS patients referred specifically for symptom evaluation (8/24, 33%). Colitis was found in patients with HPS-1 and HPS-4 genotypes.

Adolescent↗

PubMed2005

Pathology of the future: molecular profiling for targeted therapy.

Recent evidence suggests that each patient's cancer has a unique subset of molecular pathogenetic derangements. These derangements may both genetic and proteomic alterations. Genomic and proteomic research tools enable genome-wide assessment of gene expression as well as kinase driven cell signaling events. These tools are illuminating the molecular derangements of individual tumors, even if these tumors have similar morphological characteristics. A combination of laser capture microdissection with multiplexed phosphoproteomic analysis using reverse phase protein microarray technology is being used to identify protein molecular signatures of individual tumors. The in vivo state of multiple kinase driven signal pathways may be evaluated by reverse phase protein microarray with a panel of specific antibodies developed based upon our knowledge of biological processes. Molecular profiling of individual patient's tumors is currently being evaluated in clinical trials at the National Institutes of Health, National Cancer Institute for monitoring Epidermal Growth Factor (EGF) cell signaling events for patients with breast and ovarian cancer.

Forecasting↗

PubMed2004

Serum proteomics in cancer diagnosis and management.

Mass spectrometry-based diagnostics has the potential to revolutionize molecular medicine. Using modern mass-spectrometer technologies, clinical tests can be developed that are practical, robust, accurate, and inexpensive. Serum proteomic pattern profiling couples mass spectrometry with adaptive artificial-intelligence-based bioinformatics, which can now be employed to detect pathological states reflected in the serum proteome. With this approach, rapid and cost-effective tests with exquisite clinical sensitivity and specificity are emerging. These tools may dramatically change how disease is detected, monitored, and managed.

Blood Proteins↗

PubMed2003

Protein microarrays: meeting analytical challenges for clinical applications.

Protein microarrays, one emerging class of proteomic technologies, have broad applications for discovery and quantitative analysis. A rapidly expanding use of this technology is the acquisition of information about the posttranslational modifications of proteins reflecting the activity state of signal pathways and networks, and is now employed for the analysis of biopsy samples in clinical trial research.

Animals↗

PubMedDate not supplied

Pegylated, steptavidin-conjugated quantum dots are effective detection elements for reverse-phase protein microarrays.

Protein microarray technologies provide a means of investigating the proteomic content of clinical biopsy specimens in order to determine the relative activity of key nodes within cellular signaling pathways. A particular kind of protein microarray, the reverse-phase microarray, is being evaluated in clinical trials because of its potential to utilize limited amounts of cellular material obtained through biopsy. Using this approach, cellular lysates are arrayed in dilution curves on nitrocellulose substrates for subsequent probing with antibodies. To improve the sensitivity and utility of reverse-phase microarrays, we tested whether a new reporter technology as well as a new detection instrument could enhance microarray performance. We describe the use of an inorganic fluorescent nanoparticle conjugated to streptavidin, Qdot 655 Sav, in a reverse-phase protein microarray format for signal pathway profiling. Moreover, a pegylated form of this bioconjugate, Qdot 655 Sav, is found to have superior detection characteristics in assays performed on cellular protein extracts over the nonpegylated form of the bioconjugate. Hyperspectral imaging of the quantum dot microarray enabled unamplified detection of signaling proteins within defined cellular lysates, which indicates that this approach may be amenable to multiplexed, high-throughput reverse-phase protein microarrays in which numerous analytes are measured in parallel within a single spot.

Calibration↗

PubMedDate not supplied

Fractionation of serum components using nanoporous substrates.

Numerous previously uncharacterized molecules resident within the low molecular weight circulatory proteome may provide a picture of the ongoing pathophysiology of an organism. Recently, proteomic signatures composed of low molecular weight molecules have been identified using mass spectrometry combined with bioinformatic algorithms. Attempts to sequence and identify the molecules that underpin the fingerprints are currently underway. The finding that many of these low molecular weight molecules may exist bound to circulating carrier proteins affords a new opportunity for fractionation and separation techniques prior to mass spectrometry-based analysis. In this study we demonstrate a method whereby nanoporous substrates may be used for the facile and reproducible fractionation and selective binding of the serum-based biomarker material, including subcellular proteins found within the serum. Aminopropyl-coated nanoporous silicon, when exposed to serum, can deplete serum of proteins and yield a serum with a distinct, altered MS profile. Additionally, aminopropyl-coated, nanoporous controlled-pore glass beads are able to bind a subset of serum proteins and release them with stringent elution. The eluted proteins have distinct MS profiles, gel electrophoresis profiles, and differential peptide sequence identities, which vary based on the size of the nanopores. These material surfaces could be employed in strategies for the harvesting and preservation of labile and carrier-protein-bound molecules in the blood.

Electrophoresis, Polyacrylamide Gel↗