Plamen A Demirev

US Patent:

7020559, Mar 28, 2006

Filed:

Nov 17, 1999

Appl. No.:

09/856044

Inventors:

Plamen A. Demirev - College Park MD, US

Assignee:

University of Maryland - College Park MD

International Classification:

G01N 33/48

US Classification:

702 19, 702 20

Abstract:

A method for rapid identification of biological materials is presented, which exploits the wealth of information contained in genome and protein sequence databases (). In a preferred embodiment, the method utilizes the masses of a set of ions by MALDI TOF mass spectrometry of intact or treated cells (). Subsequent correlation () of each ion in the set to a protein, along with the organismic source of the protein, is performed by searching a database comprising protein molecular weights ().

US Patent:

7109038, Sep 19, 2006

Filed:

Jun 6, 2003

Appl. No.:

10/456116

Inventors:

Peter F. Scholl - Silver Spring MD, US
Plamen Demirev - Ellicott City MD, US
Andrew B. Feldman - Colulmbia MD, US

Assignee:

The Johns Hopkins University - Baltimore MD

International Classification:

G01N 33/72
G01N 33/00
G01N 24/00

US Classification:

436 66, 436 63, 436171, 436173, 436 97, 356300, 356326, 250281, 250282

Abstract:

Methods are described for detecting and quantifying occult blood in a biological sample using laser desorption mass spectrometry (LD MS). Biological samples that can be analyzed using various embodiments of the present invention include stool (fecal occult blood, FOB), and any bodily fluid including urine, cerebrospinal fluid and other bodily fluids. If the heme or heme metabolite is bound to protein, the sample is treated with acid before analysis to release the porphyrin. Some of the methods use LD MS with a time of flight analyzer (TOF) to detect and measure unbound heme, other hemoglobin metabolites and other molecules that have a porphyrin-based structure, e. g. , bilirubin, biliverdin, protoporphyrin IX, and Zinc protoporphyrin in the biological sample. In other methods, matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) is used to detect and quantify the individual α- and β-polypeptide chains of hemoglobin.

US Patent:

7270948, Sep 18, 2007

Filed:

Mar 28, 2003

Appl. No.:

10/502834

Inventors:

Plamen A. Demirev - Ellicott City MD, US
Andrew B. Feldman - Columbia MD, US
Darin Kongkasuriyachai - Walnut CA, US
Nirbhay Kumar - Bethesda MD, US
Peter F. Scholl - Baltimore MD, US

Assignee:

The Johns Hopkins University - Baltimore MD

International Classification:

C12Q 1/00

US Classification:

435 4

Abstract:

Mass spectrometric techniques are provided for detecting the presence of parasites that accumulate unbound heme in red blood cells (including malaria parasites), based on the discovery that unbound heme can be detected and quantified using mass spectrometry. In one aspect of the invention, the method includes the steps of: obtaining a blood sample from the animal; preparing a test sample on a support from the blood sample, and inserting the support into a mass spectrometer for analysis. Next one obtains a mass spectrum of the test sample and determines whether the mass spectrum contains a mass/charge signature of unbound heme. If it is determined that the mass spectrum of the test sample shows the mass/charge signature of unbound heme, the animal is diagnosed as infected with malaria parasites.

US Patent:

8481281, Jul 9, 2013

Filed:

Feb 17, 2011

Appl. No.:

13/029830

Inventors:

Plamen A. Demirev - Ellicott City MD, US
Nathan A. Hagan - Ellicott City MD, US
Miquel D. Antoine - Columbia MD, US
Jeffrey S. Lin - Silver Spring MD, US
Andrew B. Feldman - Columbia MD, US

Assignee:

The Johns Hopkins University - Baltimore MD

International Classification:

C12Q 1/04
C12Q 1/18
C12Q 1/10
C12Q 1/14

US Classification:

435 34, 435 32, 435 36, 435 38

Abstract:

The present invention is based on the discovery that drug resistance in microorganisms can be rapidly and accurately determined using mass spectrometry. A mass spectrum of an intact microorganism or one or more isolated biomarkers from the microorganism grown in drug containing, isotopically-labeled media is compared with a mass spectrum of the intact microorganism or one or more isolated biomarkers from the microorganism grown in non-labeled media without the drug present. Drug resistance is determined by predicting and detecting a characteristic mass shift of one or more biomarkers using algorithms. The characteristic mass shift is indicative that the microorganism is growing in the presence of the drug and incorporating the isotopic label into the one or more biomarkers, resulting in change in mass.

US Patent:

20040099531, May 27, 2004

Filed:

Aug 14, 2003

Appl. No.:

10/640985

Inventors:

Rengaswamy Srinivasan - Ellicott City MD, US
Hassan Saffarian - Silver Spring MD, US
Andrew Feldman - Columbia MD, US
Plamen Demirev - Ellicott City MD, US
Peter Scholl - Silver Spring MD, US

International Classification:

G01N027/26

US Classification:

204/412000, 204/407000

Abstract:

The present invention concerns a sensor array and related testing apparatus for rapidly detecting the presence and/or concentration of constituents in samples, particularly biological molecules in fluid samples, including associated testing methods. The invention can be adapted such that a plurality of the sensors each detect a different constituent so that the invention can rapidly detect multiple constituents in a single sample. The sensors may be arranged in an array and connected by a plurality of micro channels that are fed from a main channel into which the sample is introduced. Positive pressure can be applied to the main and micro channels by a micro-pump. Alternately, it can be adapted to detect one or more constituents in a plurality of separate samples. A plurality of sensors are provided, each comprising electrochemical cells comprising an anode, a cathode and a reference electrode separated from each other by one or more filters within which an electrolyte is suspended. The cathode of each sensor is particularly adapted to optimize adherence to it of the particular constituent that it is designed to detect. The electrodes of each sensor are electrically coupled to a miniature electrochemical analyzer designed to send electrical pulses (voltage or current) to the electrochemical cell, and and measure the response (current or voltage) by the electrochemical cells responsive to the pulses and then analyze the response to determine the presence and/or concentration of the constituents. The transient current or voltage responses are affected by the type and concentration of the constituent that adheres to the cathode of the particular sensor.

US Patent:

20040099536, May 27, 2004

Filed:

Aug 14, 2003

Appl. No.:

10/640984

Inventors:

Rengaswamy Srinivasan - Ellicott City MD, US
Hassan Saffarian - Silver Spring MD, US
Peter Scholl - Silver Spring MD, US
Plamen Demirev - Ellicott City MD, US
Andrew Feldman - Columbia MD, US

International Classification:

C25D011/00
G01N027/26

US Classification:

205/317000, 205/786500

Abstract:

Provided are methods of producing an electrode capable of binding an analyte thereto comprising: providing a substrate capable of binding a dithiol molecule thereto; electrochemically treating the substrate using cyclic voltammetry to provide a treated substrate having a fractal dimension of greater than about 2; and contacting the treated substrate with dithiol molecules to produce an electrode having dithiol groups attached thereto and capable of binding an analyte to be detected thereto. Also provided are methods of accumulating and detecting analytes using the electrodes produced via the methods of the present invention.

US Patent:

20040185513, Sep 23, 2004

Filed:

Jan 29, 2004

Appl. No.:

10/767910

Inventors:

Plamen Demirev - Ellicott City MD, US

International Classification:

G01N033/53
G01N033/569
G01N033/554

US Classification:

435/007310, 435/007320

Abstract:

A method for identifying small acid-soluble proteins (SASPs) by generating an increased number of biomarkers upon controllably triggering enzymatic digestion in an intact spore is disclosed. An additional embodiment of the method includes oxidizing an unknown protein in a microorganism by pre-selected oxidation facilitating agent, which causes a predetermined mass gain in Methionine, thus serving as an indicator of a particular family of proteins.

US Patent:

20040241677, Dec 2, 2004

Filed:

Nov 13, 2003

Appl. No.:

10/477648

Inventors:

Jeffrey Lin - Silver Spring MD, US
Andrew Feldman - Columbia MD, US
Plamen Demirev - Ellicott City MD, US
Peter Scholl - Silver Spring MD, US
Sean Murphy - Silver Spring MD, US

International Classification:

C12Q001/68
C12Q001/44
G06F019/00
G01N033/48
G01N033/50

US Classification:

435/006000, 435/040500, 702/019000

Abstract:

Techniques for automatically analyzing a biological sample with a microscope include obtaining a first digital image of a first field of view of the biological sample. Cell data and anomalous data are automatically determined. Cell data indicates an area co-located in the first digital image with a cell set of one or more cells of a particular type. Anomalous data indicates an area co-located in the first digital image with an anomalous set of zero or more particular objects that are anomalous to normal cells of the particular type. The cell data and the anomalous data are automatically combined to determine the particular objects inside the cell set in the first digital image. An analytical result for the biological sample is generated based on the particular objects inside the cell set. These techniques allow the automated classification and quantification of malaria in microscope views of blood smears, among other diseases.