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At least 523 records · Page 29Linked to original sources
PubMed2005

Optical coherence tomography: a new method to assess aneurysm healing.

OBJECT: Aneurysmal subarachnoid hemorrhage affects approximately 10/100,000 people per year. Endovascular coil embolization is used increasingly to treat cerebral aneurysms and its safety and durability is rapidly developing. The long-term durability of coil embolization of cerebral aneurysms remains in question; patients treated using this modality require multiple follow-up angiography studies and occasional repeated treatments. METHODS: Optical coherence tomography (OCT) is an emerging imaging modality that uses backscattered light to produce high-resolution tomography of optically accessible biological tissues such as the eye, luminal surface of blood vessels, and gastrointestinal tract. Vascular OCT probes in the form of imaging microwires are presently available--although not Food and Drug Administration-approved--and may be adapted for use in the cerebral circulation. In this study the authors describe the initial use of OCT to make visible the neck of aneurysms created in a canine model and treated with coil embolization. Optical coherence tomography images demonstrate changes that correlate with the histological findings of healing at the aneurysm neck and thus may be capable of demonstrating human cerebral aneurysm healing. CONCLUSIONS: Optical coherence tomography may obviate the need for subsequent follow-up angiography studies as well as aid in the understanding of endovascular tissue healing. Data in this study demonstrate that further investigation of in vivo imaging with such probes is warranted.

Animals↗
PubMed2003

[Capillary electrophoresis for monitoring stability of pharmaceutical proteins].

Like chemical drugs, pharmaceutical proteins have to be of strictly controlled purity to become biopharmaceuticals. Detection, identification and characterization of impurities and compounds present in purified biopharmaceuticals are of central interest. Simultaneous development of structural biology, biotechnologies and of highly resolutive analytical tools, allow significant progress in this field to be achieved. Thus, capillary electrophoresis can be advantageously used for monitoring protein stability. As illustrated by the examples of potential enzymes for detoxification of organophosphates, prophylaxis and treatment of poisoning by pesticides and nerve agents or for skin decontamination, the present feature article shows that this new methodological approach allows: to determine purity and homogeneity of proteins;to analyze their resistance to denaturing conditions such as heat or high electric fields;to detect the presence of unwanted hidden protein-bound ligands capable of altering functional conformation and stability of enzymes, and moreover susceptible to be released and to induce side effects, such as immunologic response; and to establish the role of parameters controlling the "good compromise" between conformational stability and plasticity for allowing optimal functional efficiency of enzymes. Finally, capillary electrophoresis has proved to be a pertinent tool to validate the conformity of purified enzymes to a status of biopharmaceutical.

Acetylcholinesterase↗
PubMed2003

Immunocytochemistry of the amphibian embryo--from overview to ultrastructure.

Amphibian embryos are standard research objects to study pattern formation and morphogenesis. Due to their external development and robust nature, experimental manipulations such as microinjections or transplantations can be easily performed. However, most immunocytochemical approaches addressing the specific localization of proteins are hampered by the fragility of the large and yolky embryonic cells which render high resolution staining difficult. Immunocytochemical data are therefore often restricted to either overall patterns in whole embryo preparations or to immunofluorescent localization with limited resolution on sections. High resolution or ultrastructural protein localization data are rare and can be achieved only with time consuming procedures. Here, a comparative study of immunocytochemical methods suitable for light and electron microscopy using different kinds of plastic resins is presented. Three main approaches are described: preembedding staining of whole embryos, postembedding staining of ultrathin sections and preembedding staining of vibratome sections. All the procedures are designed to study protein expression in early amphibian embryos en gros as well as en detail and the described techniques are suitable to combine two or three levels of resolution on the very same biological specimen. Examples are presented and advantages and disadvantages of the different protocols are discussed.

Animals↗
PubMed1990

IL-1 alpha or tumor necrosis factor-alpha stimulate release of three NAP-1/IL-8-related neutrophil chemotactic proteins in human dermal fibroblasts.

Human dermal fibroblasts in culture secrete three protein-like neutrophil chemotactic factors, when stimulated either with human rIL-1 alpha or IL-1 beta; not, however, after incubation with LPS. These three fibroblast-derived neutrophil-activating proteins (FINAP) could be purified by subsequently performed reversed phase and size exclusion HPLC. By high resolution SDS-PAGE, all the proteins were shown to migrate with an Mr of 6,700 (alpha-FINAP), 3,600 (beta-FINAP), and 5,300 (gamma-FINAP). All purified cytokine preparations were found to be chemotactic for human neutrophils. In addition, all FINAP induced release of lysosomal enzymes in neutrophils. Deactivation of chemotaxin-elicitable enzyme release showed cross-desensitization of all FINAP with NAP-1/IL-8. Western blot analysis of alpha-FINAP by using mAb against neutrophil-activating protein (NAP)-1/IL-8 reveals immunologic cross-reactivity with NAP-1/IL-8. By amino-terminal amino acid sequence analysis alpha-FINAP could be identified as the 77-residue extended form of NAP-1/IL-8 containing the 79-residue form as a minor contaminant. Whereas beta-FINAP has been found to be a truncation product of alpha-FINAP, gamma-FINAP shows identity with authentic melanoma growth stimulatory activity with respect to retention time upon reversed phase HPLC, high resolution SDS-PAGE, and biologic properties, as well as amino-terminal amino acid sequence. These data show that human dermal fibroblasts may actively participate in inflammatory reactions by secretion of proinflammatory cytokines.

Amino Acid Sequence↗
PubMed1989

Analysis of relaxation time data from a low-resolution 1H-NMR-pulse-spectrometer.

Systematic investigations have been undertaken in order to evaluate the potential of low resolution NMR for characterization of biological tissue (in vitro) during early post mortem period. Test measurements from corn-oil samples are compared with computer simulated data. Furthermore, time-after-excision dependence of mouse-liver tissue is presented using the in vitro protocol developed in our laboratory. Quantitative data from biexponential model fit are shown and results are discussed in terms of the "best guess" model.

Animals↗
PubMed1987

The photoelectron x-ray microscope, a possible tool for analytical soft x-ray microscopy.

In the soft x-ray region, different techniques have been recently developed which can give images of biological objects at an intermediate resolution between optical and electron microscopes. At these wavelengths, very little sample preparation is required because the image contrast is directly dependent upon the chemical composition of the sample itself and on the x-ray wavelength. X-ray microscopy can be extended to absorption microanalysis with a similar resolution, provided that the basic microscope can work through a large range of wavelengths. The photoelectron x-ray microscope that we are developing at LURE satisfies this condition. Its principle is to make a contact x-ray image of the object on a plane photocathode and then, to magnify the secondary electron image, into which it is converted, by means of an emission electron microscope. In the present state of the art, the expectable detection limit, for element maps of 0.1 micron resolution, would be near 1% in concentration.

Electron Probe Microanalysis↗
PubMed1985

Magnetic resonance imaging in human pregnancy.

Magnetic resonance imaging is a new noninvasive diagnostic technique that involves no ionizing radiation, has no known significant adverse biologic effects, and produces high resolution cross-sectional body images. When compared with sonography and x-ray computed axial tomography, magnetic resonance imaging may have several advantages. To investigate its clinical role in obstetrics, magnetic resonance imaging was used to examine 11 women with abnormal pregnancies. Prior ultrasound examination showed abnormal appearing fetuses in five, abnormalities of the amnionic fluid volume in five, and one each with a large adnexal mass and a molar pregnancy. Examples of images obtained from these women are presented and described. Maternal anatomy was well visualized in all women studied. Based on the preliminary experience, the authors believe that magnetic resonance imaging will be a useful adjunct for diagnostic visualization of normal and abnormal maternal anatomy. Detailed fetal imaging was also possible, and it is anticipated that magnetic resonance imaging will prove useful for fetal evaluation, especially fetal intracranial anatomy and fetal anatomy in pregnancies complicated by oligohydramnios. Because fetal subcutaneous fat is prominently depicted with magnetic resonance imaging, this technology may be useful for assessment of fetal nutritional status.

Female↗
PubMed1998

Confocal microscopy. Applications in research and practice of pathology.

OBJECTIVE: To discuss recent advances in the use of confocal microscopy to perform quantitative analysis of physiologic and pathologic intracellular events in the living organ. STUDY DESIGN: We developed a new confocal microscope system equipped with a microlens-arrayed multipinhole scanning disc and water-immersion objective lenses. The confocal microscope enables us to quantitate nonhomogeneous changes in the three-dimensional intracellular calcium ion concentration in a living, whole heart. RESULTS: The new system allows in situ quantitative imaging of the calcium wave in the living heart at a full video rate. Calcium waves propagating from cell to cell were frequently interrupted by calcium transients from spontaneous sinus rhythm, but low transparency of the living tissues and cell injury with laser light still remained unsolved. CONCLUSION: The evolution of the confocal microscope with high spatial and temporal resolution renders the investigation of biologic phenomena even in the living organ.

Calcium↗
PubMed1995

Resolution of catecholic tetrahydroisoquinoline enantiomers and the determination of R- and S-salsolinol in biological samples by gas chromatography-mass spectrometry.

Tetrahydroisoquinolines (TIQs) might be formed endogenously and can act centrally to promote a mechanism governing alcohol drinking behaviour. The possibility that biosynthesis occurs through a stereospecific enzymatic reaction is considered. Several TIQs were transformed into diastereomers by a two-step derivation with N-methyl-N-trimethylsilyltrifluoracetamide and R-(-)-2-phenylbutyrylic acid and were analyzed by gas chromatography-mass spectrometry (GC-MS). High resolution of the TIQ enantiomers was achieved. This method was applied to the quantification of the enantiomers of salsolinol (SAL) in urine and plasma of healthy humans. Deuterated SAL was used as the internal standard. SAL was extracted from biological material using phenyl-boronic phase cartridges and transformed into diastereomers. The sensitivity and specificity of the assay permit the determination of the enantiomeric composition of SAL in plasma and urine. The limit of quantification was found to be 100 pg/ml for each enantiomer. The described method has the advantage that optimal resolution of the SAL enantiomers without peak overlapping between analyte and other compounds can be achieved. Contrary to other findings, our GC-MS studies have demonstrated that endogenously formed SAL is racemic in plasma as well as in urine of healthy subjects.

Deuterium↗
PubMed1991

Backscattered electron imaging for high resolution surface scanning electron microscopy with a new type YAG-detector.

Double Layer Coating for backscattered electron imaging is a coating and imaging method especially suitable for high resolution scanning electron microscopy (SEM) of large biological samples. Since the backscattered electron (BSE) signal from thin metal coating layers is quite low, field emission SEM's and very sensitive BSE-detectors are required for this method. In this study an improved BSE-detector of the YAG type was used with an in-lens type field emission SEM. Two samples were investigated in order to demonstrate and to improve the potential of this new approach: (1) cryo-prepared cultured kidney cells were shadowed by electron beam evaporation with platinum-carbon (unidirectionally at a fixed angle of 45 degrees) and then coated with an additional 10 nm carbon layer; and (2) cryo-prepared trichocyst matrixes (paracrystalline structures contained in secretory granules, the trichocysts, found in Paramecium) were coated by ion beam sputtering with about 1 nm of platinum. This sample was rotated and tumbled during coating in order to obtain as uniform a metal layer as possible and then an additional 10 nm carbon layer was evaporated over the metal. When these samples were viewed at a primary beam accelerating voltage (Vo) of 10 kV or higher, contrast was good on the unidirectionally coated cell culture samples. However, trichocyst matrixes with the thinner and more uniform coating showed very poor contrast because most of the BSE detected represented beam-specimen interactions from the bulk of the sample and not in the thin platinum layer. The situation was improved by using low Vo (4 kV). Under these conditions the penetration depth of the electrons is reduced and a greater proportion of the BSE electrons are scattered by the platinum layer. The results were compared with freeze-fracture and deep-etch transmission electron microscope studies of the trichocyst matrixes from the literature: Almost similar resolution is achieved on the biological structures but a better impression of the three dimensional arrangement of the whole trichocyst matrix is obtained with the SEM. The globular particles form disc-like structures that are connected with each other by thin fibers.

Animals↗
PubMed2004

Patient-appraised couple emotion management and disease management among Chinese American patients with type 2 diabetes.

Family context exerts a strong influence on disease management among patients with chronic disease, but it is not clear which aspects of family life are most influential. This study examined the linkages between patient-appraised couple emotion management (conflict resolution, expressiveness, and respect) and disease management (biological, morale/depression, quality of life, and behavioral) among a relatively understudied group, Chinese American patients with type 2 diabetes. Significant main effects were found between patient-appraised couple emotion management, especially conflict resolution, and the morale component of disease management, but not the biological or behavioral components; both diabetes-specific and general relationship qualities (marital satisfaction) were independently linked to disease management. Acculturation did not qualify the findings. Similarities among ethnic groups in family and disease management relationships may be more common than differences.

Acculturation↗
PubMed2006

Genetic pleiotropy in Saccharomyces cerevisiae quantified by high-resolution phenotypic profiling.

Genetic pleiotropy, the ability of a mutation in a single gene to give rise to multiple phenotypic outcomes, constitutes an important but incompletely understood biological phenomenon. We used a high-resolution and high-precision phenotypic profiling approach to quantify the fitness contribution of genes on the five smallest yeast chromosomes during different forms of environmental stress, selected to probe a wide diversity of physiological features. We found that the extent of pleiotropy is much higher than previously claimed; 17% of the yeast genes were pleiotropic whereof one-fifth were hyper-pleiotropic. Pleiotropic genes preferentially participate in functions related to determination of protein fate, cell growth and morphogenesis, signal transduction and transcription. Contrary to what has earlier been proposed we did not find experimental evidence for slower evolutionary rate of pleiotropic genes/proteins. We also refute the existence of phenotypic islands along chromosomes but report on a remarkable loss both of pleiotropy and of phenotypic penetrance towards chromosomal ends. Thus, the here reported features of pleiotropy both have implications on our understanding of evolutionary processes as well as the mechanisms underlying disease.

Genes, Fungal↗
PubMed1996

Human psychopharmacology of N,N-dimethyltryptamine.

We generated dose-response data for the endogenous and ultra-short-acting hallucinogen, N,N-dimethyltryptamine (DMT), in a cohort of experienced hallucinogen users, measuring multiple biological and psychological outcome measures. Subjective responses were quantified with a new rating scale, the HRS, which provided better resolution of dose effects than did the biological variables. A tolerance study then was performed, in which volunteers received four closely spaced hallucinogenic doses of DMT. Subjective responses demonstrated no tolerance, while biological measures were inconsistently reduced over the course of the sessions. Thus, DMT remains unique among classic hallucinogens in its inability to induce tolerance to its psychological effects. To assess the role of the 5-HT1A site in mediating DMT's effects, a pindolol pre-treatment study was performed. Pindolol significantly increased psychological responses to DMT, suggesting a buffering effect of 5-HT1A agonism on 5-HT2-mediated psychedelic effects. These data are opposite to those described in lower animal models of hallucinogens' mechanisms of action.

Adult↗
PubMed2001

4Pi-confocal microscopy of live cells.

By coherently adding the spherical wavefronts of two opposing lenses, two-photon excitation 4Pi-confocal fluorescence microscopy has achieved three-dimensional imaging with an axial resolution 3-7 times better than confocal microscopy. So far this improvement was possible only in glycerol-mounted, fixed cells. Here we report 4Pi-confocal microscopy of watery objects and its application to the imaging of live cells. Water immersion of 4Pi-confocal microscopy of membrane stained live Escherichia coli bacteria attains a 4.3-fold better axial resolution as compared to the best water immersion confocal microscope. The resolution enhancement results into a vastly improved three-dimensional representation of the bacteria. The first images of live biological samples with an all-directional resolution in the 190-280 nm range are presented here, thus establishing a new resolution benchmark in live-cell microscopy.

Escherichia coli↗
PubMed1987

Pyrroloisoquinoline antidepressants. 2. In-depth exploration of structure-activity relationships.

A series of pyrrolo[2,1-a]isoquinolines, and related compounds, were examined for antidepressant-like activity, by virtue of their antagonism of tetrabenazine-induced ptosis and sedation, and inhibition of biogenic amine uptake. Thus, we have identified some of the most potent antagonists of TBZ-induced ptosis and some of the most potent inhibitors of the uptake of dopamine, norepinephrine, and serotonin (in rat brain synaptosomes) ever reported. Compounds of particular note, in this regard, are 52b, 29b, 22b, and 48b, respectively. Biological activity was chiefly manifested by the trans isomeric class. Also, through resolution of four compounds, 7b, 24b, 37b, and 48b, biological activity was found to be associated with the (+) enantiomer subgroup (salts measured at 589 nm in MeOH), corresponding to the 6S, 10bR absolute configuration for 7b, 37b, and 48b, and the 6R,10bR configuration for 24b. An X-ray determination on (+)-24b X HBr established its absolute configuration; configurations for the other compounds were verified by enantiospecific synthesis starting with (+)-(R)-2-phenylpyrrolidine. Regarding the pendant phenyl ring, diverse substitution patterns were investigated. Those substitutions that were particularly unfavorable were 3',4',5'-trimethoxy (20b), 2',3',4',5',6'-pentafluoro (34b), 2'-trifluoromethyl (38b), 3',5'-bis(trifluoromethyl) (42b), 4'-n-butyl (44b), 2'-cyano (47b), 4'-methylsulfonyl (50b), and 2'-carboxy (58b). Exceedingly potent compounds, in one way or another, were 10b-12b, 22b, 23b, 25b, 28b, 29b, 33b, 45b, 48b, 51b-53b. The pattern of aromatic substitution had a strong impact on selectivity in the uptake tests (NE vs. DA vs. 5-HT). Activity was significantly diminished by methyl substitution of 7b at the 5 (65, 66), 6 (61b), or 10b (60b) position, by changing the phenyl group of 7b to cyclohexyl (67b), benzyl (68b), or H (72), by moving the phenyl group of 7b to the 5 (69) or 10b (70) position, by expansion of ring B to an azepine (78b), and by modification of ring C to an azetidine (77b), piperidine (75b), or azepine (74b). The interaction of selected analogues with various CNS receptors is reported. Little affinity was shown for the muscarinic cholinergic receptor, suggesting a lack of anticholinergic side effects. Interestingly, 24b and 33b displayed a high affinity for the serotonin-2 receptor, analogous to mianserin and clomipramine. After the body of data was reviewed, derivatives 24b and 48b were chosen for advanced development.

Animals↗
PubMed2005

Ultrahigh-resolution optical coherence tomography with a fiber laser source at 1 microm.

We report a compact, high-power, fiber-based source for ultrahigh-resolution optical coherence tomography (OCT) near 1 microm. The practical source is based on a short-pulse, ytterbium-doped fiber laser and on generation of a continuum spectrum in a photonic crystal fiber. The broadband emission has an average power of 140 mW and offers an axial resolution of 2.1 microm in air (<1.6 microm in biological tissue). The generation of a broad bandwidth is robust and efficient. We demonstrate ultrahigh-resolution, time-domain OCT imaging of in vitro and in vivo biological tissues.

Equipment Design↗
PubMed2005

Stem cell implantation in ischemic mouse heart: a high-resolution magnetic resonance imaging investigation.

Advances in the biology of stem cells have evoked great interest in cell replacement therapies for the regeneration of heart tissue after myocardial infarction. However, results from human trials are controversial, since the destination of the injected cells, their engraftment and their long-term fate have remained unclear. Here we investigate whether transplanted cells can be identified in the intact and lesioned murine myocardium employing high-resolution MRI. Cardiac progenitor cells, expressing the enhanced green fluorescent protein (EGFP), were labeled with ultra-small paramagnetic iron-oxide (USPIO) nanoparticles and transplanted into the intact or injured myocardium of mice. Their precise location was determined with high-resolution MRI and compared with histological tissue sections, stained with Prussian blue for iron content. These experiments showed that iron nanoparticle-loaded cells could be identified at high resolution in the mouse heart. However, ischemic myocardium (after cryoinjury or left coronary artery ligation) was characterized by a signal attenuation similar to that induced by USPIO-labeled cells in T2*-weighted MR images, making detection of labeled stem cells in this area by T2*-sensitive contrast rather difficult. In animals with myocardial injury only, the signal attenuated areas were of the same size in proton density- and T2*-weighted MR images. In injured animals also receiving labeled cells the lesioned area appeared larger in T2*--than in proton density-weighted MR images. This sequence-dependent lesion size change is due to the increased signal loss caused by the iron oxide nanoparticles, most sensitively detectable in the T2*-sensitive images. Thus, using the novel combination of these two parameter weightings, USPIO-labeled cells can be detected at high resolution in ischemic myocardium.

Animals↗