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L J Kricka

Publications and source records attributed to L J Kricka.

At least 19 recordsLinked to original sources
PubMed2003

Microchip PCR.

Miniaturization of genetic tests has become an important goal. This review surveys the current progress towards the miniaturization of tests based on the polymerase chain reaction (PCR). It examines the different types of PCR microchip designs, fabrication methods,and the components of a microchip PCR device. It also discusses the problems attributable to surface chemistry of microchip components (inhibition of PCR), and the static and dynamic surface passivation strategies developed for the solution of these difficulties

Equipment Design↗
PubMed2001

Microchips, microarrays, biochips and nanochips: personal laboratories for the 21st century.

Micro miniaturization of analytical procedures is having significant impact on diagnostic testing, and will enable highly complex clinical testing to be miniaturized and permit testing to move from the central laboratory into non-laboratory settings. The diverse range of micro analytical devices includes microchips, gene chips, bioelectronic chips. They have been applied to several clinically important assays (e.g., PCR, immunoassay). The main advantages of the new devices are integration of multiple steps in complex analytical procedures, diversity of application, sub-microliter consumption of reagents and sample, and portability. These devices form the basis of new and smaller analyzers (e.g., capillary electrophoresis) and may ultimately be used in even smaller devices useful in decentralized testing (lab-on-a-chip, personal laboratories). The impact of microchips on healthcare costs could be significant via timely intervention and monitoring, combined with improved treatments (e.g., microchip-based pharmacogenomic tests). Empowerment of health consumers to perform self-testing is limited, but microchips could accelerate this process and so produce a level of self-awareness of biochemical and genetic information hitherto unimaginable. The next level of miniaturization is the nanochip (nanometer-sized features) and the technological foundation for these futuristic devices is discernable in nanotubes and self-assembling molecular structures.

Miniaturization↗
PubMed2001

Microchip module for blood sample preparation and nucleic acid amplification reactions.

A computer numerical control-machined plexiglas-based microchip module was designed and constructed for the integration of blood sample preparation and nucleic acid amplification reactions. The microchip module is comprised of a custom-made heater-cooler for thermal cycling, a series of 254 microm x 254 microm microchannels for transporting human whole blood and reagents in and out of an 8--9 microL dual-purpose (cell isolation and PCR) glass-silicon microchip. White blood cells were first isolated from a small volume of human whole blood (<3 microL) in an integrated cell isolation--PCR microchip containing a series of 3.5-microm feature-sized "weir-type" filters, formed by an etched silicon dam spanning the flow chamber. A genomic target, a region in the human coagulation Factor V gene (226-bp), was subsequently directly amplified by microchip-based PCR on DNA released from white blood cells isolated on the filter section of the microchip mounted onto the microchip module. The microchip module provides a convenient means to simplify nucleic acid analyses by integrating two key steps in genetic testing procedures, cell isolation and PCR and promises to be adaptable for additional types of integrated assays.

Cell Separation↗
PubMed2001

Agilent 2100 bioanalyzer for restriction fragment length polymorphism analysis of the Campylobacter jejuni flagellin gene.

The Agilent 2100 bioanalyzer (Agilent Technologies, Palo Alto, Calif.) utilizes capillary electrophoresis on a microchip device (LabChip 7500; Caliper Technologies, Mountain View, Calif.) that is capable of rapidly sizing small DNA fragments. To determine whether the system could replace conventional restriction fragment length polymorphism (RFLP) typing by agarose gel electrophoresis, we compared the analyzer with conventional flagellin RFLP for typing Campylobacter jejuni. Ninety-seven isolates representing 46 Fla types were initially analyzed. Correct Fla types were detected in 59% of the isolates. The major problem with the system was in resolving samples containing multiple DNA fragments differing from 8 to 20 bp. Overall, the bioanalyzer has the potential to replace conventional RFLP analysis by gel electrophoresis, but improvements in the chip separation are needed.

Autoanalysis↗
PubMed1999

Bioluminescent fusion conjugates and bioluminescent immunoassays: 1988-1998

The first part of this survey focuses on immunoassays and related ligand:binder assays (receptor:ligand, DNA probe) that use either a luciferase or a photoprotein as a label. In addition, references to assays that use a conventional label detected using a bioluminescent assay are included. The second part of the survey collects together references to publications on recombinant fusion proteins in which one of the fused proteins is bioluminescent (e.g., a luciferase or a photoprotein). References are cited by year and then alphabetically by first author. Copyright 1999 John Wiley & Sons, Ltd.

Journal Article↗
PubMed1999

Time-resolved fluorescence: 1996-1998

Luminescence continues to provide comprehensive literature surveys which will be published in most issues. These are a continuation of the literature surveys begun in 1986 in the Journal of Bioluminescence and Chemiluminescence which, up until 1998, encompassed more than 6000 references cited by year or specialized topic. With this newly named journal these searches are expanding to reflect the journal's wider scope. In future we will cover all fundamental and applied aspects of biological and chemical luminescence and include not only bioluminescence and chemiluminescence but also fluorescence, time resolved fluorescence, electrochemiluminescence, phosphorescence, sonoluminescence, lyoluminescence and triboluminescence. The compilers would be pleased to receive any comments from the readership. Copyright 1999 John Wiley & Sons, Ltd.

Journal Article↗
PubMed1999

Sonoluminescence: 1996-1998

The journal continues to provide comprehensive literature surveys which will be published in most issues. These are a continuation of the literature surveys begun in 1986 in the Journal of Bioluminescence and Chemiluminescence, and which have, up to 1998, encompassed more than 6000 references cited by year or specialized topic. With this newly named Journal these searches are expanded to reflect the Journal's wider scope. In future we will cover all fundamental and applied aspects of biological and chemical luminescence and include not only bioluminescence and chemi--luminescence but also fluorescence, time-resolved fluorescence, electrochemiluminescence, phosphorescence, sonoluminescence, lyoluminescence and triboluminescence, etc. The compilers would be pleased to receive any comments from the readership. Contact by E-mail: L. J. Kricka (larry_kricka@pathla.med. upenn.edu), and P. E. Stanley (stanley@lumiweb.com). Copyright 1999 John Wiley & Sons, Ltd.

Journal Article↗
PubMed1999

Electrochemiluminescence: 1996-1998

The journal continues to provide comprehensive literature surveys which will be published in most issues. These are a continuation of the literature surveys begun in 1986 in the Journal of Bioluminescence and Chemiluminescence, and which have up to 1998, encompassed more than 6000 references cited by year or specialized topic. With this newly named Journal these searches are expanded to reflect the Journal's wider scope. In future we will cover all fundamental and applied aspects of biological and chemical luminescence and include not only bioluminescence and chemi--luminescence but also fluorescence, time-resolved fluorescence, electrochemiluminescence, phosphorescence, sonoluminescence, lyoluminescence and triboluminescence, etc. The compilers would be pleased to receive any comments from the readership. Contact by e-mail: L. J. Kricka (larry_kricka@path1a.med. upenn.edu), and P. E. Stanley (stanley@LUMIWEB.COM). Copyright 1999 John Wiley & Sons, Ltd.

Journal Article↗
PubMed1999

Nucleic acid detection technologies -- labels, strategies, and formats.

Currently, no consensus exists on assay formats, labels, or detection reactions for nucleic acid assays. New labels continue to be developed and tested, and recent candidates include acetate kinase, firefly luciferase, and genes for enzymes. An additional trend is toward nonamplification strategies (e.g., branched chain and dendrimer type assays) as alternatives to the popular PCR and related amplification strategies. The new wave of microanalytical devices (microchips, with nanoliter to microliter internal volumes), massively parallel simultaneous test arrays, and the desire to produce hand-held sensors present new challenges and requirements for nucleic acid detection methods (e.g., analysis of large arrays of micrometer-sized spots of nucleic acid with high resolution). Here I review selected developments and new directions in nucleic acid assays.

DNA Probes↗
PubMed1999

Human anti-animal antibody interferences in immunological assays.

PURPOSE: The scope and significance of human anti-animal antibody interference in immunological assays is reviewed with an emphasis on human anti-animal immunoglobulins, particularly human anti-mouse antibodies (HAMAs). ISSUES: Anti-animal antibodies (IgG, IgA, IgM, IgE class, anti-isotype, and anti-idiotype specificity) arise as a result of iatrogenic and noniatrogenic causes and include human anti-mouse, -rabbit, -goat, -sheep, -cow, -pig, -rat, and -horse antibodies and antibodies with mixed specificity. Circulating antibodies can reach gram per liter concentrations and may persist for years. Prevalence estimates for anti-animal antibodies in the general population vary widely and range from <1% to 80%. Human anti-animal antibodies cause interferences in immunological assays. The most common human anti-animal antibody interferent is HAMA, which causes both positive and negative interferences in two-site mouse monoclonal antibody-based assays. Strategies to prevent the development of human anti-animal antibody responses include immunosuppressant therapy and the use of humanized, polyethylene glycolylated, or Fab fragments of antibody agents. Sample pretreatment or assay redesign can eliminate immunoassay interferences caused by anti-animal antibodies. Enzyme immunoassays, immunoradiometric assays, immunofluorescence, and HPLC assays have been designed to detect HAMA and other anti-animal antibodies, but intermethod comparability is complicated by differences in assay specificity and lack of standardization. CONCLUSIONS: Human anti-animal antibodies often go unnoticed, to the detriment of patient care. A heightened awareness on the part of laboratory staff and clinicians of the problems caused by this type of interference in routine immunoassay tests is desirable. Efforts should be directed at improving methods for identifying and eliminating this type of analytical interference.

Animals↗
PubMed1998

Integrated cell isolation and polymerase chain reaction analysis using silicon microfilter chambers.

White blood cells are isolated from whole blood in silicon-glass 4.5-microliter microchips containing a series of 3.5-micron feature-sized 'weir-type' filters, formed by an etched silicon dam spanning the flow chamber. Genomic DNA targets, e.g., dystrophin gene, can be directly amplified using the polymerase chain reaction (PCR) from the white cells isolated on the filters. This dual function microchip provides a means to simplify nucleic acid analyses by integrating in a single device two key steps in the analytical procedure, namely, cell isolation and PCR.

Cell Separation↗