Atomic force microscopy: a forceful way with single molecules.
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The atomic force microscope (AFM) now routinely provides images that reveal subnanometer surface structures of biomolecules. The sensitivity and precision of AFM provide new opportunities for studying the mechanical properties of biomolecules and their interactions in their native environment. (+info)
Diagnosis of rickettsial diseases using samples dried on blotting paper.
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The use of filter paper is an inexpensive and convenient method for collecting, storing, and transporting blood samples for serological studies. In addition, samples occupy little space and can be readily transported without refrigeration. Rickettsial diseases often evolve according to an epidemic mode and are now considered reemerging diseases, especially in developing countries, under conditions where fieldwork could be difficult. The suitability of collecting whole-blood specimens on filter paper discs for rickettsial antibody assay was evaluated. Dried blood specimens from 64 individuals with antibodies to Coxiella burnetii, Bartonella quintana, or Rickettsia conorii were tested for rickettsial antibodies by microimmunofluorescence. Although occasional titers were 1 or 2 dilutions lower than those of tested serum samples, no statistically significant differences were observed. Among patients with negative serology, no false positives were found. This study demonstrated that the recovery of antibodies from finger-stick blood dried on filter paper after elution produces results comparable to those obtained by recovering antibodies from serum. Storing paper samples for 1 month at room temperature or at 4 degrees C did not significantly affect the level of antibodies recovered. This report shows the utility of this sample collection method in developing countries where refrigeration is not possible and venipuncture is problematic. (+info)
Femtochemistry.
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The topic of femtochemistry is surveyed from both theoretical and experimental points of view. A time-dependent wave packet description of the photodissociation of the O---C---S molecule reveals vibrational motion in the transition-state region and suggests targets for direct experimental observation. Theoretical approaches for treating femtosecond chemical phenomena in condensed phases are featured along with prospects for laser-controlled chemical reactions by using tailored ultrashort chirped pulses. An experimental study of the photoisomerization of retinal in the protein bacteriorhodopsin is discussed with an aim to gain insight into the potential energy surfaces on which this remarkably efficient and selective reactions proceeds. Finally, a prospective view of new frontiers in femtochemistry is given. (+info)
Microanalysis of cardiolipin in small biopsies including skeletal muscle from patients with mitochondrial disease.
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Cardiolipin is a specific mitochondrial phospholipid that is present in mammalian tissues in low concentration. To measure cardiolipin in small biopsies from patients with mitochondrial disease, we developed a new technique that can detect subnanomolar levels of well-resolved molecular species, the most abundant of which are tetralinoleoyl-cardiolipin (L(4)) and trilinoleoyl-oleoyl-cardiolipin (L(3)O). To this end, a fluorescence-labeled derivative of cardiolipin (2-[naphthyl-1'-acetyl]-cardiolipin dimethyl ester) was formed and analyzed by high performance liquid chromatography. Cardiolipin was measured in skeletal muscle biopsies from 8 patients with mitochondrial disease and in 17 control subjects. In 5 patients with mitochondrial disease, cardiolipin content was higher than normal (2. 4;-7.0 vs. 0.4;-2.2 nmol/mg protein). In 3 patients with mitochondrial disease, the L(4)/L(3)O ratio was lower than normal (2;-4 vs. 4;-6). Cardiolipin was also measured in various rat and dog muscle tissues. The L(4)/L(3)O ratio was higher in condensed "muscle" type mitochondria (heart ventricle, skeletal muscle, ratios 4;-7) than in orthodox "liver" type mitochondria (liver, smooth muscle, heart auricular appendage, H9c2 myoblasts, ratios 0.4;-3), suggesting that the L(4)/L(3)O proportion is important for cristae membrane structure. We concluded that the L(4)/L(3)O ratio is a tissue-specific variable that may change in the presence of mitochondrial disease. The new method is suitable to measure cardiolipin in muscle biopsies in order to estimate concentration of mitochondria. (+info)
Survey of the Korean population for 9 short tandem repeat loci.
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The short tandem repeats with repeat units ranging from two to several nucleotides became a powerful tool in the field of forensic identification and paternity determination as well as for research in human gene mapping. Allele and genotype frequencies for 9 short tandem repeats including HUMCSF1PO, HUMTH01, HUMPLA2A1, HUMF13A01, HUMCYAR04, HUMLIPOL, HUMHPRTB, HUMCD4, and HUMFABP were determined using PCR and subsequent analysis of the PCR products by denaturing polyacrylamide gel electrophoresis followed by silver-staining. DNA samples were obtained from about 100 Korean people and amplified in a thermocycler adopting glass capillaries rather than traditional tubes. We found that the bovine serum albumin was an essential additive for the capillary PCR, presumably to coat the inner surface of the capillary which may adsorb Taq DNA polymerase. The capillary thermocycler was very effective in reducing the cycling time such that most of the amplification reactions could be finished within 30 min albeit the PCR product was less than that for the tube systems. All loci except HUMHPRTB met the Hardy-Weinberg expectations according to the exact test. The cumulative power of discrimination (PD) was 0.9999998 and the power of exclusion (POE) for the paternity test was a little low, being 0.9873989. (+info)
Radioimmune determination of hypoxanthine phosphoribosyltransferase crossreacting material in erythrocytes of Lesch-Nyhan patients.
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We have developed a sensitive radioimmunoassay capable of detecting and quantitating 20 ng of hypoxanthine phosphoribosyltransferase (EC 2.4.2.8; IMP:pyrophosphate phosphoribosyltransferase) protein. For this assay, hypoxanthine phosphoribosyltransferase from human erythrocytes was iodinated with 125I under mild conditions using hydrogen peroxide and lactoperoxidase attached to Sepharose-4B. Antisera prepared against homogeneous human hypoxanthine phosphoribosyltransferase precipitates the iodinated enzyme as effectively as the unlabeled enzyme. The radioimmunoassay has been used to look for hypoxanthine phosphoribosyltransferase crossreacting material in hemolysates from sixteen different patients with a marked genetic deficiency of this enzyme characteristic of the Lesch-Nyhan syndrome. Fifteen hemolysates contained no detectable (less than 1% of normal) crossreacting material. One hemolysate contained a normal amount of crossreacting material. Hypoxanthine phosphoribosyltransferase from this patient (E.S.) has been shown to be a Km mutant enzyme. (+info)
Species-specific monoclonal antibodies for rapid identification of Bartonella quintana.
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Seven species-specific monoclonal antibodies (MAbs) to Bartonella quintana were produced and characterized. The MAbs were of the immunoglobulin G class and reacted only with 13 B. quintana strains in indirect microimmunofluorescence and Western immunoblotting assays. They did not react with eight other Bartonella spp., including Bartonella henselae, the most closely related species, and a selected MAb did also not react with nine other strains of gram-negative bacteria. The MAbs reacted mainly with a 34-kDa protein epitope of B. quintana which was shown to be species specific by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Four of five body lice experimentally infected with B. quintana were found to be positive for the organism in microimmunofluorescence assays with one MAb. These MAbs may provide a specific, simple, rapid, and low-cost tool for the identification of B. quintana and the diagnosis of infections due to the microorganism. (+info)
Synthesis and antibacterial activities of some 1,2,4-triazole derivatives.
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Reactions of 3-amino-1,2,4-triazole with some dicarboxylic acid anhydrides and diketones were studied. The structural assignments of the compounds obtained from the reactions are based on elemental analyses and spectral data. The compounds were screened for their in vitro antibacterial activities. (+info)