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PubMed2003

[Direct detection of malignant mutations in patients with hypertrophic cardiomyopathy].

We determined the prevalence of mutations considered malignant in the genes for beta-myosin heavy chain (MYH7, 11 mutations) and troponin T (TNNT2, 5 mutations) in 30 patients with hypertrophic cardiomyopathy aged 18 to 60 years, 83% of whom had familial antecedents of hypertrophic myocardiopathy or sudden death. Mutations were identified with polymerase chain reaction followed by restriction enzyme digestion and agarose gel electrophoresis. Direct analysis identified 16 mutations in 2 of the 30 patients (7%): one women diagnosed at the age of 25 years as carrying the MYH7453cysteine mutation, and a 60-year-old women with the TNNT2278 cysteine mutation. These cases illustrate the considerable clinical heterogeneity that characterizes carriers of these mutations. Clinical manifestations can range from severe hypertrophy or early sudden death to the absence of symptoms up to advanced age.

Adolescent↗

PubMed1995

A novel amber mutation in a beta zero-thalassaemia gene (beta 37TGG-->TAG), with direct detection by mapping the restriction fragments in amplified genomic DNA.

A novel amber mutation, a G to A substitution at the second position of codon 37 in the beta-globin gene that changes the tryptophan coding triplet (TGG) to a termination codon (TAG), was found in a Chinese beta-thalassaemia carrier. The mutant gene creates an additional Dde I recognition site and eliminates the Ava II site, so this point mutation can be directly identified by restriction enzyme analysis.

Adult↗

PubMed1980

Anti-self receptors. I. Direct detection of H-2L region-restricted receptors on murine thymocytes.

A high proportion (20--50%) of murine thymocytes form rosettes with either syngeneic or allogeneic erythrocytes. The specificity of this interaction was investigated by measuring the ability of different erythrocyte sonicates to inhibit rosette formation. With erythrocyte sonicates from recombinant mouse strains it was demonstrated that rosetting with syngeneic erythrocytes was mediated by H-2L and/or H-2D region-restricted receptors. The specificity of autorosetting was directly mapped to the H-2L region by the inability of erythrocyte sonicates from the BALB/c-H-2dm2 mutant, an H-2L-deletion mutant, to inhibit the rosetting of wild-type (BALB/c) thymocytes. The B10,2D2-H-2dm1 mutant, which has substantially modified H-2L and H-2D antigens, supported this conclusion. Furthermore, anti-H-2L sera were able to specifically block the inhibition of rosetting by erythrocyte sonicates. The above procedures clearly implicated the H-2L region in the thymocyte rosetting of d and k haplotypes. With the s haplotype the rosetting receptor was mapped to the H-2L/H-2D region, whereas with the b and q haplotypes rosetting was only mapped to the D end of the H-2 complex. This study also suggested complete cross-reaction between the thymocyte receptors carried by the k and d haplotypes, whereas the receptors of b, q, and s haplotypes were haplotype specific. In addition, the inhibition assay indicated that the rosetting of thymocytes with allogeneic and xenogeneic (rat) erythrocytes was mediated by a receptor primarily directed against self-H-2L. Finally, the critical role played by the H-2L region in this rosetting phenomenon was demonstrated by the inability of thymocytes from the H-2L-deletion mutant (H-2dm2) to rosette with syngeneic, allogeneic (rat) erythrocytes.

Animals↗

PubMed2005

Direct detection of DNA with an electrocatalytic threading intercalator.

Herein we report the synthesis, intercalating properties, and analytical applications of an imidazole-substituted naphthalene diimide, N,N'-bis(3-propylimidazole)-1,4,5,8-naphthalene diimide (PIND), functionalized with electrocatalytic redox moieties. PIND was prepared in a single-step reaction from the corresponding dianhydride. Attachment of the redox moieties to PIND relied upon ligand exchange with one of the liable chloride ligands of an Os(bpy)2Cl2 (bpy = 2,2'-bipyridine) complex. The Os(bpy)2Cl2 complex was grafted onto PIND through coordinative bonds with the two imidazole groups at its termini, forming a PIND-[Os(bpy)2Cl]+ compound (PIND-Os). Gel electrophoretic studies revealed that PIND-Os binds more strongly to double-stranded DNA (ds-DNA) than its parent compound 1,4,5,8-naphthalene diimide. The naphthalene diimide group binds to ds-DNA in a "classical" threading intercalation mode, while the two Os(bpy)2Cl+ pendants interact with DNA via electrostatic interaction, reinforcing the intercalation by "locking up" the naphthalene diimide group in place. An electrochemical biosensor was fabricated using the redox-active and catalytic PIND-Os intercalator. An increase in sensitivity of 2500-fold over direct voltammetry was obtained in electrocatalytic amperometry, making this an interesting system for amperometric DNA sensing. Under optimized experimental conditions, the biosensor allowed the detection of a 50-mer target DNA in the range of 1.0-300 pM with a detection limit of 600 fM (1.5 amol, 23 fg).

Biosensing Techniques↗

PubMed1999

Direct detection of endogenous histamine in rat peritoneal mast cells by in-capillary derivatization high-performance capillary electrophoresis.

A simple method for the detection of endogenous histamine in rat peritoneal mast cells was evaluated using on-line mode in-capillary derivatization high-performance capillary electrophoretic (ICD-HPCE) techniques, which were previously developed by our group [S. Oguri et al., J. Chromatogr. A, 787 (1997) 253-260]. The method involves a suspension of peritoneal mast cells (1 x 10(6) cells/ml of saline) collected from a male Wistar rat (eight weeks of age), which are directly introduced into the capillary tube from the anodic end by hydrostatic injection (at 25 cm height, for 2-20 s). When a high-voltage potential (25 kV) is applied to the capillary, which is already filled with the run buffer containing both a lysing reagent (SDS, sodium dodecyl sulfate,) and a derivatizing reagent (OPA, o-phthalaldehyde; NAC, N-acetylcysteine), histamine in the mast cells was detected at high-sensitivity level without further procedures. During ICD-HPCE, the mast cells injected in the capillary were lysed with the lysing reagent, free histamine released from the cell was labeled with the derivatizing reagent, and its derivative was electromigrated, separated and detected with a fluorescence detector (excitation wavelength at 340 nm, emission wavelength at 450 nm) in a fused-silica capillary (75 cm x effective length x 50 microm I.D.). The run buffer used was a 20 mM phosphate-borate buffer (pH 10) containing 20 mM SDS, 2 mM OPA and 2 mM NAC. This method was also examined with regard to the possibility of its use for determination of histamine at the single mast cell level.

Animals↗

PubMed1988

Direct detection of HIV RNA expression in seropositive subjects.

The polymerase chain reaction (PCR) and reverse transcription were used to assess human immunodeficiency virus type 1 (HIV1) RNA expression in peripheral blood mononuclear cell samples from seropositive subjects. HIV RNA was detected from seropositive subjects who had no symptoms, lymphadenopathy syndrome, and acquired immunodeficiency syndrome. DNA PCR of the samples used for RNA extraction showed that seventeen of eighteen (94%) contained HIV proviral DNA. Eleven (65%) of the seventeen DNA-positive samples were also positive for HIV RNA, including samples from four patients undergoing antiviral drug treatment. Serum HIV antigen assays detected only six (32%) of the nineteen PCR-positive samples. Owing to the speed and high sensitivity of PCR for HIV detection, this technique will be suitable for monitoring antiviral therapy and the virus load of people with HIV infections.

Cells, Cultured↗

PubMed2005

Multicenter evaluation of BBL CHROMagar MRSA medium for direct detection of methicillin-resistant Staphylococcus aureus from surveillance cultures of the anterior nares.

Active surveillance for methicillin-resistant Staphylococcus aureus (MRSA) is among the strategies recommended by the Society for Healthcare Epidemiology of America for control of nosocomial MRSA infections. Infection control and laboratory personnel desire rapid, sensitive, and inexpensive methods to enhance surveillance activities. A multicenter study was performed to evaluate a new selective and differential chromogenic medium, BBL CHROMagar MRSA (C-MRSA) medium (BD Diagnostics, Sparks, MD), which enables recovery and concomitant identification of MRSA strains directly from nasal swab specimens taken from the anterior nares. Specimens were inoculated to C-MRSA and Trypticase soy agar with 5% sheep blood agar (TSA II, BD Diagnostics). Mauve colonies on C-MRSA at 24 h and 48 h and suspicious colonies on TSA II were confirmed as Staphylococcus aureus by Gram stain morphology and a coagulase test. In addition, the results of C-MRSA were compared to results of susceptibility testing (five different methods) of S. aureus strains isolated on TSA II. A total of 2,015 specimens were inoculated to C-MRSA and TSA II. Three hundred fifty-four S. aureus isolates were recovered; 208 (59%) were oxacillin (methicillin) susceptible and 146 (41%) were oxacillin resistant (MRSA). On C-MRSA, 139/146 or 95.2% of MRSA isolates were recovered, whereas recovery on TSA II was 86.9% (127/146) (P = 0.0027). The overall specificity of C-MRSA was 99.7%. When C-MRSA was compared to each susceptibility testing method, the sensitivity and specificity, respectively, were as follows: oxacillin MIC by broth microdilution, 94.4% and 96.7%; oxacillin screen agar, 94.3% and 96.7%; PBP2' latex agglutination, 93.7% and 98.5%; cefoxitin disk diffusion, 95.0% and 98.1%; and mecA PCR, 95.1% and 98.1%. In this study, C-MRSA was superior to TSA II for recovery of MRSA from surveillance specimens obtained from the anterior nares and was comparable to conventional, rapid, and molecular susceptibility methods for the identification of MRSA isolates.

Agar↗

PubMed1998

Direct detection and quantitative determination of bovine lactoferricin and lactoferrin fragments in human gastric contents by affinity mass spectrometry.

Lactoferricin (Lfcin) is a bioactive fragment of lactoferrin derived from the bactericidal and putative lymphocyte receptor binding domain(s) located within the N-lobe of lactoferrin. Although known to be liberated from at least three species of lactoferrin, conditions leading to Lfcin generation in vivo and factors affecting its distribution are still not known. Recently, we have developed a method of surface-enhanced laser desorption/ionization (SELDI) affinity mass spectrometry using n-butyl terminal groups for surface-enhanced affinity capture (SEAC) to quantify not only Lfcin generated in vivo but also other lactoferrin fragments. Unlike previous efforts to detect lactoferrin and Lfcin with specific antibodies, the SELDI affinity assay distinguished lactoferrin, lactoferrin fragments, Lfcin and unrelated peptides without their interference with each other. To evaluate Lfcin generation in vivo, the experimental design involved feeding 200 mL of 10 mg/mL (1.22 x 10(-4) mol/L) bovine lactoferrin to an adult. Gastric contents were recovered 10 min after ingestion. Lfcin produced in vivo was directly captured by the SEAC device. The amount of Lfcin in the gastric contents was 16.91 +/- 2.65 micrograms/mL (5.350 +/- 0.838 x 10(-6) mol/L). However, a large proportion of the ingested lactoferrin was not completely digested. Lactoferrin fragments containing the Lfcin region were analyzed by in situ hydrolysis with pepsin after being captured by the SEAC device. As much as 5.740 +/- 0.702 x 10(-5) mol/L of the partially degraded lactoferrin fragments were found to contain the Lfcin region, including peptide domains 17-43, 17-44, 12-44, 9-58, and 16-76 of bovine lactoferrin. These results show that bovine Lfcin can be produced in the human stomach after ingestion of an infant formula supplemented with bovine lactoferrin. It is now important to determine whether Lfcin is generated in the intestinal tract of formula-fed and breast-fed infants, and geriatric patients consuming foods enriched with lactoferrin.

Adult↗

PubMed2006

Direct detection of the formation of V-amylose helix by single molecule force spectroscopy.

An important polysaccharide, amylose crystallizes as a regular single left-handed helix from a propanol, butanol, or iodine solution. However, its solution structure remains elusive because amylose does not form molecular solutions in these solvents, and standard spectroscopic techniques cannot be exploited to determine its structure. Using AFM, we forced individual amylose chains adsorbed to a surface to enter these poor solvents and carried out stretch-release measurements on them in solution. In this manner, we directly captured the formation of individual amylose helices induced by butanol and iodine. With an accuracy approaching that of X-ray diffraction on amylose crystals, we determined that the pitch of the helix in solution is 1.3 angstroms/ring. We also directly measured the force driving the formation of the helix in solution to be 50 pN. SMD simulations in explicit butanol reproduced the AFM-measured force-extension curves and revealed that the long plateau feature is caused by the rupture of O(2)n-O(6)(n+6) and O(3)n-O(6)(n+6) hydrogen bonds and by the unwinding of the helix. We also found that amylose helices formed in iodine solution are more compliant and hysteretic as compared to helices in butanol, which extend/relax reversibly. In iodine solution, the formation of the helix is inhibited by force and limited by the slow kinetics of the amylose-iodine complex. By forcing individual molecules into poor solvents and performing force spectroscopy measurements in solution, our AFM approach uniquely supplements X-ray diffraction and NMR methods for investigating solution conformations of insoluble biopolymers.

Amylose↗

PubMed1993

Direct detection of wild poliovirus circulation by stool surveys of healthy children and analysis of community wastewater.

Cartagena, Colombia, was one of the last cities in the Americas known to have endemic poliomyelitis. After 3 cases were identified in 1991, two approaches for detecting continued silent transmission of wild polioviruses within a high-risk community were used: stool surveys of healthy children and virologic analysis of community sewage. Wild type 1 polioviruses were isolated from 8% of the children studied and from 21% of sewage samples. The proportions of wild polioviruses, vaccine-related polioviruses, and nonpolio enteric viruses were similar for both approaches. Wild poliovirus sequences were also amplified directly from processed sewage samples by the polymerase chain reaction using primer pairs specific for the indigenous type 1 genotype. The last reported cases associated with wild polioviruses in the Americas occurred in Colombia (8 April 1991) and Peru (23 August 1991). Direct sampling for wild polioviruses in high-risk communities can provide further evidence that eradication of the indigenous wild polioviruses has been achieved in the Americas.

Child, Preschool↗

PubMed2000

Direct detection of crosslinks of collagen and elastin in the hydrolysates of human yellow ligament using single-column high performance liquid chromatography.

Collagen and elastin are recognized as two major connective tissue proteins of human yellow ligament. In both collagen and elastin there are many kinds of intra- or intermolecular crosslinks. Pyridinoline (Pyr) and deoxypyridinoline (Dpyr) are mature crosslinks which maintain the structure of the collagen fibril. Desmosine (Des) and isodesmosine (Isodes) represent the major crosslinking components of elastin. Pentosidine (Pen), which is a senescent crosslink and one of the advanced glycation end products, accumulates with age in tissue proteins including collagen. We developed a direct and one-injection HPLC method to measure Pyr, Dpyr, Des, Isodes, and Pen in the hydrolysate of human yellow ligament. This method used one column and two detectors. Recovery rates of Pyr, Dpyr, Pen, Des, and Isodes were 86.4-98.3, 83.6-96.8, 78.7-95.6, 83.6-97.9, and 85.6-99.3%, respectively (n = 8). The intraassay coefficients of variation for Pyr, Dpyr, Pen, Des, and Isodes were 3.7, 4.1, 5.4, 4.5, and 4.7%, respectively (n = 8), and the interassay coefficients of variation for Pyr, Dpyr, Pen, Des, and Isodes were 4.4, 5.1, 4.9, 4.6 and 4.1%, respectively. Linear regression analysis showed the linearity (r = 0.99, P = 0.0001) of calibration line for each Pyr, Dpyr, Pen, Des, and Isodes. Using this method, we investigated age-related changes in the crosslinks of collagen and elastin in human yellow ligament. There was a significant correlation between Pen and age, but no correlations with Pyr, Dpyr, Des, and Isodes. We believe that this method is useful for investigating the content of these crosslinks in both collagen and elastin under various conditions.

Chromatography, High Pressure Liquid↗

PubMed1996

Direct detection of Mycobacterium tuberculosis in sputum samples from Guinea Bissau by an rRNA target-amplified test system.

SETTING: There is a need for more sensitive and rapid methods for laboratory confirmation in the diagnosis of tuberculosis. OBJECTIVE: To investigate the applicability of a target rRNA amplified test system (AMTDT, Gen-Probe, CA) for rapid detection of Mycobacterium tuberculosis. DESIGN: The rRNA amplified test system was compared to standard methods for acid fast microscopy and mycobacterial culture for the demonstration of M. tuberculosis in sputum samples from 247 patients in Guinea Bissau with suspected tuberculosis. RESULTS: The highest incidence of positive samples was obtained with the AMTDT test. Out of 274 sputum samples 96 (35%) were positive by the AMTDT test, 82 (30%) were positive by culture and 38 (14%) by direct microscopy. Using culture as reference method the sensitivity of the test was 85% (after discrepancy analysis 87%), and the specificity was 86% (after discrepancy analysis 93%). CONCLUSION: The sensitivity and specificity of the AMTDT test used in this setting indicates that it may be a valuable complement for improving the laboratory diagnosis of tuberculosis.

Bacteriological Techniques↗

PubMed1990

Direct detection of linker DNA bending in defined-length oligomers of chromatin.

Linker DNA, which connects between nucleosomes in chromatin, is short and, therefore, may be essentially straight and inflexible. We have carried out hydrodynamic and electron microscopic studies of dinucleosomes--fragments of chromatin containing just two nucleosomes--to test the ability of linker DNA to bend. We find that ionic conditions that stabilize the folding of long chromatin cause linker DNA in dinucleosomes to bend, bringing the two nucleosomes into contact. The results uphold a key prediction of the solenoid model of chromosome folding and suggest a mechanism by which proteins that are separated along the DNA can interact by direct contact.

Animals↗

PubMed1998

Development of a multiplex-PCR for direct detection of the genes for enterotoxin B and C, and toxic shock syndrome toxin-1 in Staphylococcus aureus isolates.

As well as conventional methods such as immunodiffusion, ELISA, or agglutination for the detection of toxin production in Staphylococcus aureus, amplification techniques like PCR allow a very sensitive and specific identification of the genes responsible for enterotoxin B and C, and TSST-1 production. These toxins might be a cause of the toxic shock syndrome (TSS). For that reason an easy and quick test system for determining the toxin production pattern of S. aureus isolates is desirable so that strains suspected to be toxin producers may be identified much faster and easier. In the present investigation, a new multiplex-PCR method was used that allowed single bacterial colonies grown on agar plates to be used directly in the PCR assay without preceding preparation. This procedure generated information concerning the presence of seb, sec-1 and tst genes within 4 h in a single test. To analyse the sensitivity and the specificity of this procedure, 100 methicillin-resistant S. aureus (MRSA), 50 coagulase-negative staphylococci and 50 other eubacterial isolates were tested initially with sets of single primer pairs followed by a combined multiplex-PCR. Results of this amplification technique were compared to a conventional and widely used method for toxin detection, reversed passive latex agglutination (RPLA). With the RPLA assay results as the basis, sensitivity and specificity of the seb and tst primer sets were 100%, whereas sensitivity and specificity of the sec-1 primer set were 100% and 82%, respectively. With the sec-1 primer set, two isolates were identified as carrying the corresponding toxin gene although the RPLA test did not show any detectable toxin. The multiplex-PCR rapidly generated reliable information concerning the toxin-producing capacity of staphylococcal strains and could be easily integrated into a multiplex procedure described previously. The latter enabled the identification of specific PCR products for eubacteria and staphylococci as well as the detection of the coa and mecA genes.

Bacterial Toxins↗

PubMed2004

Electronic structure and photochemistry of squaraine dyes: basic theoretical analysis and direct detection of the photoisomer of a symmetrical squarylium cyanine.

The photoisomerization kinetics of a squaraine dye has been the object both of experimental investigation and of interpretation in the framework of a qualitative theoretical model formulated by the aid of simple HMO calculations and orbital symmetry considerations. Such a model has first confirmed that the electronic structure and the spectroscopic properties of symmetrical squaraines are related to those of the parent cyanines, with ketocyanines as intermediate systems. Extension of the approach to structures twisted by 90[degree] about a polymethine bond has then provided insight into the electronic aspects and the mechanism of the photoisomerization of the squaraine under study. The reaction, previously indirectly investigated by fluorescence analysis, has been directly monitored by laser flash photolysis. These experiments indicate that, while photoisomerization is likely the main radiationless decay route from the spectroscopic minimum of the lowest excited singlet state (S(1)), the cis photoisomer is produced with only a 1% yield, likely because of an unfavourable cis/trans branching ratio from the perpendicular minimum of the S(1)-state potential energy surface. In contrast with what found for symmetrical cyanines, an increase in the solvent polarity was found to accelerate both the direct, excited-state reaction and, to a much larger extent, the ground-state back-isomerization. Such observations are consistent with predictions of the theoretical model and provide a clue for the identification of the isomerization coordinate.

Journal Article↗

PubMed2002

Direct detection and quantitation of He@C60 by ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry.

In this paper, we report negative ion microelectrospray Fourier-transform ion cyclotron resonance (FT-ICR) mass spectrometry of C60 samples containing approximately 1% 3He@C60 or 4He@C60. Resolving He@C60- and 4He@C60- from C60 containing 3 or 4 13C instead of 12C atoms is technically challenging, because the target species are present in low relative abundance and are very close in mass. Nevertheless, we achieve baseline resolution of 3He@C60- from 13C3(12C57-) and 4He@C60- from 13C4(12C56-) in single-scan mass spectra obtained in broadband mode without preisolation of the ions of interest. The results constitute the first direct mass spectrometric observation of endohedral helium in a fullerene sample at this (low) level of incorporation. The results also demonstrate the feasibility of determining the extent of He incorporation from the FT-ICR mass spectral peak heights. The present measurements are in agreement with those obtained by the pyrolysis method [1-3]. Although limited in sensitivity, the mass spectral method is faster and easier than pyrolysis.

Journal Article↗

PubMed1999

Direct detection of common mutations in the familial Mediterranean fever gene (MEFV) using naturally occurring and primer mediated restriction fragment analysis. Mutation in brief no. 257. Online.

The MEFV gene involved in familial Mediterranean fever was recently cloned and four distinct sequence alterations (M680I, M694V, M6941 and V726A) were identified at the 3'-most exon. We genotyped 170 unrelated FMF patients from various ethnic groups in Israel and found that mutation M694V predominates in North African Jews, that mutation V726A is common in Jewish patients other than North African Jews and that all four mutations occur in patients of Arabian origin, namely, Moslems, Christians and Druze. Since these four distinct sequence alterations seem to account for the majority of mutations identified in FMF patients from the middle east, we have devised a simple protocol using PCR mediated site directed mutagenesis or naturally occurring recognition sites to scan for these mutations.

Cytoskeletal Proteins↗

PubMed1997

Direct detection of the internal acyl migration reactions of benzoic acid 1-O-acylglucuronide by 13C-labeling and nuclear magnetic resonance spectroscopy.

1-O-Acyl-beta-D-glucopyranuronates can undergo irreversible binding to proteins mainly through internal acyl migration reactions, which may have toxicological significance. A new method based on the 13C-labeling and nuclear magnetic resonance (NMR) spectroscopy has been developed to study the reactivity of the 1-O-acyl-beta-D-glucopyranuronate of benzoic acid. In phosphate buffer (pH 7.4) solution at 37 degrees C, the glucuronide showed apparent first-order degradation kinetics (T1/2, 125 min), and concurrent and sequential appearance of 2-, 3- and 4-O-acyl isomers as both alpha- and beta-anomers was observed. The isomeric glucuronides were identified by two-dimensional NMR of the reaction mixture. The direct approach using 13C-labeling and NMR could also provide insights into the reactivities of other labile drug acylglucuronides and their isomeric glucuronides.

Benzoates↗