PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Molecular Probes”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed2005

Molecular recognition of alpha-cyclodextrin (CD) to choral amino acids based on methyl orange as a molecular probe.

The molecular recognition interaction of alpha-CD to chiral amino acids was investigated by using spectrophotometry based on methyl orange as a molecular probe. The molecular recognition ability depended on the inclusion formation constants. The molecular recognition of alpha-CD to aromatic amino acids was the order: DL-tryptophan > L-tryptophan > L-phenylalanine > L-tyrosine approximately DL-beta-3,4-dihydroxy-phenylalanine; whereas for aliphatic amino acids, the order was: L-iso-leucine > L-leucine approximately L-methionine approximately DL-mehtionine > D-leucine. The effect of temperature on the inclusion interaction was examined and the thermodynamic parameters of inclusion process, delta G, delta H, delta S, were determined. The experimental results indicated that the inclusion process was an exothermic and enthalpy-driven process accompanied with a negative or minor positive entropic contribution. The inclusion interaction between alpha-CD and amino acids satisfied the law of enthalpy-entropy compensation. The compensation temperature was 291 K.

Amino Acids, Aromatic↗
PubMed1990

Molecular probe protocol for determining carrier status in Duchenne and Becker muscular dystrophies.

By use of cDNA probes, molecular deletions were identified in 66.6% of 42 patients with Duchenne muscular dystrophy (DMD) or Becker muscular dystrophy (BMD). Owing to this high deletion rate, a new strategy for detecting DMD/BMD carriers is feasible in which the polymerase chain reaction is used as an initial screen for detecting the deletions occurring in specific deletion-prone exons. Because the deletions do not occur randomly, specific cDNA probes are utilized first with Southern blot analysis. Identification of a deletion permits direct analysis for DMD carrier status and removes the inherent limitations of the conventional restriction fragment length polymorphism technique. Carrier status is determined by scanning the autoradiographs with a densitometric spectrophotometer or by detection of a junction fragment.

Bacterial Proteins↗
PubMed2005

Friction force microscopy as an alternative method to probe molecular interactions.

Friction force microscopy was applied to study protein-carbohydrate interactions that are important in many cellular recognition processes. The expression and structure of carbohydrates can be investigated using lectins as molecular probes since they recognize different types of sugar molecules. Lectins (concanavalin A and lentil lectin, recognizing mannose-type carbohydrates) were attached to the probing tip and carboxypeptidase Y (possessing complementary carbohydrates) was immobilized on a modified glass surface using microcontact printing. The results obtained from friction force maps and dependencies on the loading rate (measured in a physiological buffer) were divided in two distinct groups. The first group of results obtained for lectin-protein complexes was assigned to molecular recognition events, whereas the other including all control measurements was attributed to nonspecific interaction. All results presented here indicate that friction force microscopy can be successfully employed to study recognition processes.

Journal Article↗
PubMed2000

Using molecular beacons to probe molecular interactions between lactate dehydrogenase and single-stranded DNA.

The interactions between two key macromolecular species, nucleic acids and proteins, control many important biological processes. There have been limited effective methodologies to study these interactions in real time. In this work, we have applied a newly developed molecular beacon (MB) DNA probe for the analysis of an enzyme, lactate dehydrogenase (LDH), and for the investigation of its properties of binding with single-stranded DNA. Molecular beacons are single-stranded oligonucleotide probes designed to report the presence of specific complementary nucleic acids by fluorescence detection. The interaction between LDH and MB has resulted in a significant fluorescence signal enhancement, which is used for the elucidation of MB/LDH binding properties. The processes of binding between MB and different isoenzymes of LDH have been studied. The results show that the stoichiometry of LDH-5/MB binding is 1:1, and the binding constant is 1.9 x 10(-7) M(-1). We have also studied salt effects, binding sites, temperature effects, pH effects, and the binding specificities for different isoenzymes. Our results demonstrate that MB can be effectively used for sensitive protein quantitation and for efficient protein-DNA interaction studies. MB has a signal transduction mechanism built within the molecule and can thus be used for the development of rapid protein assays and for real-time measurements.

DNA, Single-Stranded↗
PubMed2004

[Designed molecular probes in brain research: molecular imaging of IP2 receptor in the human brain].

The study of the role of prostaglandins in living human brain requires a highly designed non-invasive molecular probe with a specific function in the central nervous system and high stability in an in vivo system in addition to the ability of blood-brain-barrier penetration. We succeeded in designing 15R-TIC, which binds with a novel prostacyclin receptor subtype (IP2) expressed specifically in the central nervous system. 15R-TIC exhibited a distinct nerve-protecting effect in both high oxygen and in vivo ischemic conditions. In addition, a rapid C-methylation reaction, developed in order to incorporate a short-lived 11C-positron nuclide into the molecule, realized the synthesis of 15R-[11C]TIC methyl ester with the radioactivity of 2.5 GBq. The molecular imaging was established for both monkey and human brains by intravenous injection of this positron emission tomography (PET) probe.

Animals↗
PubMed1997

Molecular Probe Data Base (MPDB).

Molecular Probe Data Base contains detailed information on synthetic oligonucleotides with a sequence of up to 100 nucleotides. This database prevalently contains information related to human oligonucleotides used in diagnostics. Molecular Probe Data Base has been made available on-line through the Internet by means of Network Information Retrieval (NIR) tools since 1993. Two years ago, a collaboration with EMBL Data Library was also set up, so that the Molecular Probe Data Base has been integrated with other molecular biology data banks in the sphere of the SRS WWW network browser. In this paper, the most recent enhancements and the current status of the Molecular Probe Data Base are briefly presented.

Base Sequence↗
PubMed2001

Screening for clostridium botulinum type A, B, and E in cooked chilled foods containing vegetables and raw material using polymerase chain reaction and molecular probes.

A molecular method was used for the detection of Clostridium botulinum spores of type A, B, and E in commercial cooked and pasteurized vegetable purées and in the raw materials (vegetables and other ingredients). The method allowed the detection of less than 8 spores/g of product for C. botulinum type A, less than 1 spore/g for proteolytic type B, less than 21 spores/g for nonproteolytic type B, and less than 0.1 spore/g for type E. Thirty-seven samples of raw vegetables and ingredients were tested for the presence of C. botulinum type A, B, and E; 88 and 90 samples of vegetable purées were tested, respectively, for the presence of C. botulinum type A and B and for the presence of C. botulinum type E. All samples were negative, suggesting that the prevalence of C. botulinum in these vegetable purées and the raw ingredients is probably low.

Clostridium botulinum↗
PubMed2002

A microscale-molecular weight sensor: probing molecular diffusion between adjacent laminar flows by refractive index gradient detection.

A detection scheme that measures the refractive index gradient (RIG) between adjacent laminar flows in a microfluidic device has been used to develop a microscale-molecular weight sensor. The behavior of low Reynolds number flows has been well documented and shows that molecular transport (mixing) between adjacent laminar flows occurs by molecular diffusion between flow boundaries. A diode laser beam, incident upon and illuminating the entire width of a microchannel, measured the transverse concentration gradient at two different positions along a microchannel. The concentration gradient is impacted by the transverse diffusion from a flow with analyte into a flow initially without analyte. The RIG that forms as analyte diffuses from one adjacent flow to the other causes the laser beam, impinging orthogonal to the RIG through the microchannel, to be deflected. The angle of deflection is then monitored on a position-sensitive detector (PSD) at two different positions along the axis of flow to provide a measurement of analyte diffusion. The two positions are just after the flow initially without analyte merges with the flow initially containing all of the analyte (upstream) and then after the two streams have had more time to diffuse together (downstream). The ratio of the PSD signals obtained at the two positions along the flow, downstream signal divided by the upstream signal, is readily correlated to the analyte diffusion coefficient and, thus, the analyte molecular weight for a given class of compounds. The device was evaluated as a molecular weight sensor for poly(ethylene glycol) (PEG) solutions over a molar mass range from 106 to 22,800 g/mol. The ratio signal was found to be both independent of PEG concentration and sensitive to molecular weight changes for samples ranging from 960 to 22,800 g/mol. Independence of concentration is important for obtaining a reliable molecular weight measurement. The limit of detection for 11,840 g/mol PEG measured at the upstream detection position was determined to be 56 ppm, equivalent to 4.5 x 10(-6) RI (3sigma). This technique provides a much needed universal detection method, without requiring analyte derivatization chemistry (e.g., fluorescence), for microfluidic analyses that are becoming increasingly useful in monitoring chemical systems such as continuous-flow reactors or batch polymerization processes. Thus, the molecular weight determination capability is potentially applicable to other compound classes, such as DNA or proteins.

Journal Article↗
PubMed2002

Speciation of thermotolerant Campylobacter isolates involved in foodborne disease by means of DNA restriction analysis and molecular probes.

The molecular identification of several strains of Campylobacter jejuni and Campylobacter coli involved in foodborne disease was carried out by investigating the restriction profiles of their chromosomal DNA and by DNA/DNA hybridization. Cleavage with EcoRV allowed the visualization of a 3 kb DNA fragment characteristic of C. jejuni, whereas restriction with ClaI allowed the identification of a 9.3 kb DNA fragment, also characteristic of C. jejuni, and a DNA duplet of 9.5-10 kb, specific to C. coli. Restriction analysis with enzyme BglII allowed the visualization of DNA fragments of 3.5, 4, and 6.7 kb, characteristic of C. jejuni. C. jejuni subsp. doylei strains investigated shared a higher genetic homology among themselves-as determined by DNA/DNA hybridization-than with C. jejuni subsp. jejuni. A DNA probe, initially designed by Korolik et al. (Korolik, V.; Coloe, P. J.; Krishnapillai, V. J. Gen. Microbiol. 1988, 134, 521-529), including a DNA fragment encoding an antigenic membrane protein of 31.5 kDa in C. jejuni, when used as probe, allowed the specific identification of all strains of C. jejuni through the detection of strong hybridization signals in two BglII DNA fragments of 2.3 and 2.5 kb, which were not observed in C. coli. Cleavage of chromosomal DNA with BglII-either alone or coupled with probing assays with specific probes-proved to be a valuable tool for the speciation of Campylobacter isolates involved in foodborne disease.

Campylobacter Infections↗
PubMed2004

Glycoside hydrolase carbohydrate-binding modules as molecular probes for the analysis of plant cell wall polymers.

Novel molecular probes have been developed for the analysis and detection of polysaccharides in plant cell walls using carbohydrate-binding modules (CBMs) derived from modular glycoside hydrolases belonging to families 2a, 6, and 29. Recombinant forms of these proteins containing his-tags, in conjunction with anti-his-tag detection, provide a flexible system that utilizes CBMs as molecular probes in a range of applications. Assays for the rapid analysis of the binding of CBMs to polysaccharides and oligosaccharides using nitrocellulose-based CBM macroarrays and microtiter plate-based CBM capture and competitive-inhibition assays are described. We also demonstrate the use of CBMs with his-tags for the localization of their target ligands in planta. The generation of molecular probes from other families of CBMs will dramatically increase the repertoire of molecular probes available to determine the developmental and functional aspects of plant cell walls.

Biopolymers↗
PubMed1996

Molecular probe data base (MPDB).

The molecular probe data base (MPDB) contains detailed information on synthetic oligonucleotides, including their identification, target genes, applications and bibliographic references. It is available on-line through Internet and can be searched by using Network Information Retrieval tools. In this article the most recent enhancements of MPDB, both in terms of data contents and new ways of access, are described. These include a recently established collaboration with EMBL Data Library, in the sphere of SRSWWW network browser, in view of a better integration of MPDB with other molecular biology databases.

Computer Communication Networks↗
PubMed1995

Designing a molecular probe for muscarinic acetylcholine receptor (mAChR) imaging.

Radiolabeled molecular probes have demonstrated the potential for in vivo quantification of cell surface receptor concentration as a function of disease. Molecular biology has been instrumental in the design of these probes for in vivo studies, as exemplified by a molecular probe for muscarinic acetylcholine (mACh) receptor imaging. On a technical level, molecular biology has led to a better understanding of the selectivity of a radiolabeled probe in vitro. On a physiologic level, a combination of molecular biology and nuclear medicine provides an opportunity to validate in vivo what has been learned about receptors in vitro.

Animals↗
PubMed2004

Lighting up tumors with receptor-specific optical molecular probes.

Accurate and rapid detection of tumors is of great importance for interrogating the molecular basis of cancer pathogenesis, preventing the onset of complications, and implementing a tailored therapeutic regimen. In this era of molecular medicine, molecular probes that respond to, or target molecular processes are indispensable. Although numerous imaging modalities have been developed for visualizing pathologic conditions, the high sensitivity and relatively innocuous low energy radiation of optical imaging method makes it attractive for molecular imaging. While many human diseases have been studied successfully by using intrinsic optical properties of normal and pathologic tissues, molecular imaging of the expression of aberrant genes, proteins, and other pathophysiologic processes would be enhanced by the use of highly specific exogenous molecular beacons. This review focuses on the development of receptor-specific molecular probes for optical imaging of tumors. Particularly, bioconjugates of probes that absorb and fluoresce in the near infrared wavelengths between 750 and 900 nm will be reviewed.

Animals↗
PubMed1987

Seizure activity and cortical spreading depression monitored by an extrinsic potential-sensitive molecular probe.

Using surface fluorescence and reflectance measurements from the exposed cerebral cortex, several potential-sensitive molecular probes, primarily oxonol V, have been evaluated as indicators of electrical activity changes developing during seizure activity in the mongolian gerbil. Intraventricular injection of bicuculline, picrotoxin, or KCl produced characteristic cyclic molecular probe fluorescence intensity decreases that could be abolished by the uncoupler CCCP or the mitochondrial electron transport inhibitor rotenone. Smaller fluorophore signals were observed when KCl was applied topically to the exposed cortex. In some cases, as the animals were recovering from anoxia induced by nitrogen inhalation, oscillations similar to those due to spreading depression were observed in both the oxonol V and pyridine nucleotide signals. In all experiments, the molecular probe signals closely followed those of the intrinsic pyridine nucleotides. The drug-induced oxonol V signal alterations have been provisionally interpreted as due at least in part to the reduction of the mitochondrial membrane potential that accompanies a state 4 to state 3 transition. Measurements at the oxonol V fluorescence excitation wavelength indicated that only small changes in the reflectance signal occurred during seizure activity suggesting minimal blood volume change contributions to the extrinsic probe signal.

Animals↗
PubMed1996

Clinical utility of molecular probes in lymphoproliferative disorders.

The use of molecular probes to diagnose and evaluate human malignancies has been most prominent in the disease category of malignant lymphoma. While this technology is daunting, it has gained rapid entry into the laboratories of both academic and community hospitals. This is because the molecular analysis of genetic changes in human disease, especially the human lymphomas, contributes to many facets of care including aiding the diagnosis, providing prognosis and helping to monitor the disease process. This review aims to highlight both the current routinely available technology and its practical applications in human lymphoma.

Humans↗
PubMed1987

Molecular probe for identification of medically important Candida species and Torulopsis glabrata.

A cloned DNA fragment from Candida albicans containing the gene for the protein actin was used to probe the molecular structure of the actin gene of several medically important yeasts (C. albicans, Candida stellatoidea, Candida tropicalis, Candida pseudotropicalis, Candida krusei, Candida parapsilosis, Candida guilliermondii, and Torulopsis glabrata). Whole-cell DNA from each species was digested with restriction endonucleases, electrophoresed on agarose gels, and transferred to nitrocellulose. Radioactively labeled C. albicans actin gene was hybridized to the DNA fragments on the nitrocellulose. The C. albicans probe produced a strong signal with all of the Candida DNAs tested, indicating considerable conservation of this gene. In addition, the actin genes of all of the species tested were found to have no internal EcoRI or SalI restriction sites. With the exception of C. guilliermondii, all of the species tested had a single internal HindIII recognition site. However, the location of flanking restriction sites was found to be species specific. For all of the enzymes tested, the locations of the flanking restriction sites in C. albicans and C. stellatoidea were identical; all of the other strains yielded fragments clearly distinct from one another. These differences provide a molecular tool for the differentiation of medically important Candida species.

Actins↗
PubMed2006

Ionic calcium determination in skim milk with molecular probes and front-face fluorescence spectroscopy: simple linear regression.

The purpose of this study was to determine if the ionic calcium content of skim milk could be determined using molecular probes and front-face fluorescence spectroscopy. Current methods for determining ionic calcium are not sensitive, overestimate ionic calcium, or require complex procedures. Molecular probes designed specifically for measuring ionic calcium could potentially be used to determine the ionic calcium content of skim milk. The goal of the current study was to develop foundation methods for future studies to determine ionic calcium directly in skim milk and other dairy products with molecular probes and fluorescence spectroscopy. In this study, the effect of pH on calcium-sensitive fluorescent probe (Rhod-5N and Fluo-5N) performance using various concentrations of skim milk was determined. The pH of diluted skim milk (1.9 to 8.9% skim milk), was adjusted to either 6.2 or 7.0, after which the samples were analyzed with fluorescent probes (1 microM) and front-face fluorescence spectroscopy. The ionic calcium content of each sample was also determined using a calcium ion-selective electrode. The results demonstrated that the ionic calcium content of each sample was highly correlated (R2 > 0.989) with the fluorescence intensities of the probe-calcium adduct using simple linear regression. Higher than suggested ionic calcium contents of 1,207 and 1,973 microM were determined with the probes (Fluo-5N and Rhod-5N) in diluted skim milk with pH 7.0 and 6.2, respectively. The fluorescence intensity of the probe-calcium adduct decreased with a decrease in pH for the same ionic calcium concentration. This study demonstrates that Fluo-5N and Rhod-5N can be used to determine the ionic-calcium content of diluted milk with front-face fluorescence spectroscopy. Furthermore, these probes may also have the potential to determine the ionic calcium content of undiluted skim milk.

Animals↗