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PubMed1999

Tetrairidium, a four-atom cluster, is readily visible as a density label in three-dimensional cryo-EM maps of proteins at 10-25 A resolution.

Heavy metal clusters derivatized to bind to designated chemical groups on proteins have great potential as density labels for cryo-electron microscopy. Smaller clusters offer higher resolution and penetrate more easily into sterically restricted sites, but are more difficult to detect. In this context, we have explored the potential of tetrairidium (Ir(4)) as a density label by attaching it via maleimide linkage to the C-terminus of the hepatitis B virus (HBV) capsid protein. Although the clusters are not visible in unprocessed cryo-electron micrographs, they are distinctly visible in three-dimensional density maps calculated from them, even at only partial occupancy. The Ir(4) label was clearly visualized in our maps at 11-14 A resolution of both size variants of the HBV capsid, thus confirming our previous localization of this site with undecagold (Zlotnick, A., Cheng, N., Stahl, S. J., Conway, J. F., Steven, A. C., and Wingfield, P. T., Proc. Natl. Acad. Sci. USA 94, 9556-9561, 1997). Ir(4) penetrated to the interior of intact capsids to label this site on their inner surface, unlike undecagold for which labelling was achieved only with dissociated dimers that were then reassembled into capsids. The Ir(4) cluster remained visible as the resolution of the maps was lowered progressively to approximately 25 A.

Capsid↗

PubMed2001

Interleukin-8 administration enhances venous thrombosis resolution in a rat model.

BACKGROUND: Therapy for deep vein thrombosis (DVT) resolution in those patients in whom a complication or contraindication to anticoagulation occurs is limited. As prior work suggests that thrombus maturation involves early influx of neutrophils (PMN) and neovascularization, we hypothesized that administering the proinflammatory/proangiogenic chemokine interleukin (IL)-8 might accelerate thrombus resolution. MATERIALS AND METHODS: An established rodent model of DVT (inferior vena cava [IVC] ligation) was used whereby daily intravenous recombinant human IL-8 (1 microg) or vehicle control was administered, with sacrifice at 4 and 8 days. Prior to sacrifice and at harvest, duplex ultrasound of the DVT and femoral venous pressure measurements were performed. Thrombi were analyzed by immunohistochemical techniques for PMN, monocytes, and neovascularization; for chemokines, by enzyme-linked immunoassay; and fibrosis, by hydroxyproline assay and trichrome staining. RESULTS: IL-8 accelerated thrombus dissolution 4 days after IVC ligation, with 6-fold increased thrombus blood flow by duplex ultrasound and a 23% increased absolute femoral venous pressure compared with controls (both P < 0.05). These findings may be partially explained by the fact that animals receiving IL-8, as compared with controls, had 2.5-fold greater thrombus neovascularization (with a trend continuing to 8 days) and increased PMN at 4 days. Thrombus vascular endothelial growth factor was significantly reduced at 8 days postligation, while monocyte chemotactic protein-1 and macrophage inflammatory protein-1alpha were not altered by IL-8 administration. At 8 days post-IVC-ligation, fibrosis was 12-fold greater with IL-8 treatment compared with controls. CONCLUSIONS: A proinflammatory/proangiogenic thrombus milieu, as conferred by IL-8, enhances thrombus resolution and underscores the important relationship between neovascularity and inflammation.

Animals↗

PubMed1993

IFN-gamma produced in vivo during the first two days is critical for resolution of murine Leishmania major infections.

Resolution of murine infection with Leishmania major is dependent upon the presence of IFN-gamma during the first week of infection. To more precisely determine the period during which IFN-gamma is critical, we infected footpads of resistant C3H/HeN mice with amastigotes of L. major and treated these mice with neutralizing monoclonal Ab (MAb) specific for IFN-gamma on successive days. Mice treated with anti-IFN-gamma MAb on or before day 2 had significantly enlarged lesions, and increased parasites in lesions, compared with mice treated with an isotype control MAb. In contrast, mice treated with anti-IFN-gamma MAb on day 3 or later resolved their lesions and had no parasites at the inoculation site. Related experiments obtained with a neutralizing MAb specific for TNF-alpha demonstrated the critical role TNF-alpha plays in resolution of Leishmania infection. Thus, IFN-gamma and TNF-alpha were both critical for resolution of infection with L. major, with IFN-gamma's role limited to the first 2 days.

Animals↗

PubMed1994

High-resolution anatomy from in situ human brain.

We have generated a spatially accurate, high-resolution three-dimensional (3D) volume of brain anatomy from cryosectioned whole human head. The head of a female cadaver was cryosectioned on a heavy duty cryomacrotome (PMV, Stockholm Sweden) modified for quantitative digital image capture. Serial images (1024(2), 24-bit) were captured directly from the cryoplaned specimen blockface in 500-micron intervals and reconstructed to a 3D data volume. Data were placed into the Talairach coordinate system to create a volume of brain anatomy for atlas reference. We resampled the volume at 500 microns along the sagittal, coronal, and horizontal planes and enhanced the images by digitally editing the background. The spatial resolution of the original digitized images provided sufficient anatomic detail to clearly delineate gray and white matter and neural structures, including major fiber pathways, subthalamic nuclei, and laminae. We developed a compact disk and controlling software program to enable the viewer to select planes of orientation, display, and copy individual to sections at higher resolution. Animation proved useful in the conveyance of system anatomy as structures are shown traversing through the neuroaxis. Postmortem cryosectioning paired with this computerized presentation allowed the complete 3D volume data to be distributed and shared as an educational, clinical, and research resource.

Aged↗

PubMed2002

On the effects of spatial filtering--a comparative fMRI study of episodic memory encoding at high and low resolution.

The effects of spatial filtering in functional magnetic resonance imaging were investigated by reevaluating the data of a previous study of episodic memory encoding at 2 x 2 x 4-mm(3) resolution with use of a SPM99 analysis involving a Gaussian kernel of 8-mm full width at half maximum. In addition, a multisubject analysis of activated regions was performed by normalizing the functional images to an approximate Talairach brain atlas. In individual subjects, spatial filtering merged activations in anatomically separated brain regions. Moreover, small foci of activated pixels which originated from veins became blurred and hence indistinguishable from parenchymal responses. The multisubject analysis resulted in activation of the hippocampus proper, a finding which could not be confirmed by the activation maps obtained at high resolution. It is concluded that the validity of multisubject fMRI analyses can be considerably improved by first analyzing individual data sets at optimum resolution to assess the effects of spatial filtering and minimize the risk of signal contamination by macroscopically visible vessels.

Adult↗

PubMed2002

Effects of image resolution on autoradiographic measurements of posterior cingulate activity in PDAPP mice: implications for functional brain imaging studies of transgenic mouse models of Alzheimer's Disease.

Fluorodeoxyglucosepositron emission tomography (PET) studies find that persons with Alzheimer's disease have preferential reductions in posterior cingulate activity. Using fluorodeoxyglucose autoradiography, we found that transgenic mice overexpressing a mutant form of the human amyloid precursor protein have preferentially reduced activity in the same region, providing a potential brain imaging indicator of Alzheimer's disease in these animals. In this study, we considered the feasibility of using in vivo imaging techniques, such as PET, to detect this reduction despite their limitations in spatial resolution. Autoradiographic measurements of posterior cingulate activity were remeasured in the previously studied PDAPP transgenic and littermate control mice after the images were filtered to lower spatial resolutions. We continued to detect significantly lower cingulate activity in the transgenic mice when the images were blurred to 0.50 mm, failed to detect significantly abnormal activity when the images were blurred to 0.75 mm, and, indeed, found significantly higher activity when the images were blurred to 1.0 mm. Reversal in direction of the abnormality appears attributable to a previously observed truncation in the corpus callosum in PDAPP mice. With the possible exception of future in vivo imaging techniques that have a spatial resolution greater than or equal to 0.50 mm and high sensitivity, noninvasive functional brain imaging techniques like PET may not be suitable for detecting declines in regional activity in PDAPP mice. It remains possible that these imaging techniques will prove useful in transgenic mouse lines that do not exhibit the same morphological abnormalities in neighboring white matter regions.

Alzheimer Disease↗

PubMed2005

Inter-breath-hold registration for the production of high resolution cardiac MR volumes.

High resolution MRI images of the beating heart permit observation of detailed anatomical features and enable quantification of small changes in metrics of cardiac function. To obtain approximately isotropic sampling with an adequate spatial and temporal resolution, these images need to be acquired in multiple breath-holds. They are, therefore, often affected by through-plane discontinuities due to inconsistent breath-hold positions. This paper presents a method to correct for these discontinuities by performing breath-hold-by-breath-hold registration of high resolution 3D data to radial long axis images. The corrected images appear free of discontinuities, and it was found that they could be delineated more reproducibly than uncorrected images. This reduces the sample size required to detect systematic changes in blood pool volume by 57% at end systole and 78% at end diastole.

Algorithms↗

PubMed1998

Resolution of experimental vasogenic brain edema at different intracranial pressures.

Resolution of vasogenic brain edema was examined using the infusion edema model in rabbits. Texas Red-albumin (MW 66,000 D) and sodium fluorescein (MW 376 D) dissolved in artificial cerebrospinal fluid (aCSF) were infused into the white matter of the left frontal lobe of the brain. To quantify the edema fluid cleared by the ventricular system, ventriculo-cisternal perfusion was performed with aCSF. A closed cranial window, implanted above the left parietal brain, served for studying resolution of the artificial edema fluid via the subarachnoid space. CSF-samples were collected in 30 minutes-intervals and analysed with a spectrophotometer. Clearance of edema fluid was examined under low (2-5 mm Hg), medium (9-12 mm Hg), or high (14-17 mm Hg) intracranial pressures (ICP). In the low pressure-group, both edema fluid markers were found in the ventriculo-cisternal and subarachnoid perfusate at 60 and 90 min, in the group with moderately increased ICP at 90 and 120 min, respectively. In the high ICP-group both fluorescence dyes appeared not less than 90 min in the ventricular system, while no increase at all could be found in the subarachnoid space. Our results imply that resolution of edema fluid via both the ventricular system and the subarachnoid space depends on the actual ICP level.

Animals↗

PubMed1994

Formation and resolution of human peritumoral brain edema.

In 16 patients with 21 metastatic brain tumors and 9 patients with a malignant glioma, tumor volume, volume of the edematous tissue, edema production, speed of edema propagation and edema resolution were examined by using the CT. Edema production was determined according to a technique described previously and ranged between 0.09 and 1.63 ml/h in metastases and between 0.42 and 3.49 ml/h in gliomas. The speed of edema propagation ranged from 0.2-2.2 mm/h. Edema resolution can take place within the tissue (i.e. reabsorption into blood) as well by drainage into the ventricular or subarachnoid CSF. In a few small metastases with a small perifocal edema (without contact to the ventricule or the subarachnoid space) the amount of edema resolution within the tissue could be determined and averaged 0.0086 ml/h/cm3. This probably represents the reabsorption of edema fluid into capillaries within the edematous tissue. If this value is used to calculate the edema reabsorption in larger tumors, the resulting data are considerable lower than the respective edema production rate of that tumor. This indicates, that in larger tumors the main fraction of the edema fluid is draining into the ventricular and/or subarachnoid CSF.

Blood-Brain Barrier↗

PubMed1985

Ho'oponopono, "to make right": Hawaiian conflict resolution and metaphor in the construction of a family therapy.

It has been noted in the literature that community conflict resolution rituals have many structural and functional similarities to the goals and methods of psychotherapy. A Hawaiian form of conflict resolution called ho'oponopono ("to make right, orderly, correct") is a case where a conflict resolution format actually was used to create a culturally appropriate family therapy. This was done under the sponsorship of a Hawaiian social welfare organization with Hawaiian ancestry therapists. An important element in the transformation and usefulness of ho'oponopono as a Hawaiian therapy is the maintenance and incorporation of metaphoric understandings about the nature and dynamics of Hawaiian social relations.

Conflict, Psychological↗

PubMed1993

Resolution and sensitivity enhancement of heteronuclear correlation for methylene resonances via 2H enrichment and decoupling.

Monodeuterated methylene positions exhibit substantially superior spectral characteristics in 1H-13C correlation experiments as compared to diprotio signals. A combination of 2H decoupling and multiplet editing of HMQC and HSQC experiments provides resolution enhancement for both stereoselective and random fractionally deuterated samples. For HMQC experiments with [2-2HR,2-13C]glycine-labeled E. coli thioredoxin (11.7 kDa), 3-fold increases in both 1H and 13C resolution result in a complementary 9-fold enhancement in sensitivity. Owing to a smaller improvement in 13C resolution, the corresponding enhancements for the HSQC experiment are 2-fold less.

Carbon Isotopes↗

PubMed1993

High-resolution sonographic guidance for transjugular liver biopsy.

A prospective randomized study was performed to compare conventional right internal jugular vein catheterization technique with high-resolution sonographically guided catheterization for transjugular liver biopsy. Forty-seven patients were assigned to undergo either conventional or high-resolution sonographically guided right internal jugular vein catheterization for transjugular liver biopsy. Sonographic guidance was significantly better than conventional guidance, reducing the number of failed catheterizations, from 22% (5 of 23) to 0% (0 of 24) (p < .05). Sonography also reduced the mean number (+/- SD) of passes required to catheterize the vein from 4.21 +/- 1.53 to 1.54 +/- 0.66 (p < .001) and was successful in 100% (5 of 5) of patients in whom conventional catheterization failed. High-resolution sonographic guidance is strongly recommended for transjugular liver biopsy in patients at high risk for bleeding.

Adult↗

PubMed1979

Visual resolution, contrast sensitivity, and the cortical magnification factor.

This study shows that photopic contrast sensitivity and resolution can be predicted by means of simple functions derived by using the cortical magnification factor M as a scale factor of mapping from the visual field into the striate cortex. We measured the minimum contrast required for discriminating the direction of movement or orientation of sinusoidal gratings, or for detecting them in central and peripheral vision. No qualitative differences were found between central and peripheral vision, and almost all quantitative differences observed could be removed by means of a size compensation derived from M. The results indicated specifically that (1) visual patterns can be made equally visible if they are scaled so that their calculated cortical representations become equivalent; (2) contrast sensitivity follows the same power function of the cortical area stimulated by a grating at any eccentricity; (3) area and squared spatial frequency are reciprocally related as determinants of contrast sensitivity; and (4) acuity and resolution are directly proportional to M, and the minimum angle of resolution is directly proportional to M-1. The power law of spatial summation expressed in (2) and (3) suggests the existence of a central integrator that pools the activity of cortical neurons. This summation mechanism makes the number of potentially activated visual cells the most important determinant of visibility and contrast sensitivity. The functional homogeneity of image processing across the visual field observed here agrees with the assumed anatomical and physiological uniformity of the visual cortex.

Brain Mapping↗

PubMed1979

Characterization of alpha-1-antitrypsin by isoelectric focusing on an ultrathin polyacrylamide gel layer. An economic high-resolution system for determining PiM subtypes.

Through the use of ultrathin layer polyacrylamide gel isoelectric focusing it is possible to obtain a resolution of the bands of alpha 1AT so as to be able to easily recognize all six PiM subtypes. The optimal resolution of the PiM subtypes is obtained without deforming the pattern of the Pi phenotypes. In addition to high resolution, ultrathin layer polyacrylamide gel isoelectric focusing permits a notable reduction of fees to 1/5 of the usual.

Adult↗

PubMed1985

High resolution cytogenetic evaluation of couples with recurring fetal wastage.

Both high resolution and routine chromosome analyses were used to study couples with a history of two or more spontaneous abortions in early pregnancy. In the 20 couples studied, two of the women were found to have an inversion. One paracentric inversion, (13)(q13.1q22.3), was apparent on routine analysis. The small pericentric inversion (11)(p11.12q12.3), was only detected by high resolution techniques. Given the low yield and increased cost and effort involved, we do not believe that high resolution studies are justified for screening couples with repeated abortions.

Abortion, Habitual↗

PubMed1979

The demonstration of the auditory ossicles by high resolution CT.

The high resolution CT scanning system introduced by EMI in 1978 has added a new dimension to computerised tomography in otology. The apparatus used for this study was an EMI CT 5005 body scanner adapted for head and neck scanning and incorporating a high resolution facility. The latter has proved most advantageous in areas of relatively high differential absorption, so that its application to the demonstration of abnormalities in the petrous temporal bone, and in particular middle ear disease, has been very rewarding. Traumatic ossicular disruptions may now be demonstrated and the high contrast of CT often shows them better than conventional hypocycloidal tomography. The stapes is also better visualised and congenital abnormalities of its superstructure have been recorded. These studies have been achieved with a very acceptable level of radiation to the eye, lens and cornea and the technique is clearly a rival to conventional pluridirectional tomography in the assessment of the petrous temporal bone. With further design improvements high resolution CT could completely replace existing techniques.

Adolescent↗

PubMed1985

Cointegration and resolution mediated by IS101 present in plasmid pSC101.

A certain class of cointegrate plasmids was found to occur between a pSC101 derivative and a second plasmid pBV320 in E. coli F- cells. Cleavage analysis and DNA sequencing showed that the cointegrate plasmid contained direct repeats of an insertion sequence IS101 at the recombination junctions, indicating that formation of cointegrates was mediated by IS101, which is a natural constituent of pSC101. These cointegrates were formed only in cells which contained the transposon gamma-delta, suggesting that the gamma-delta sequence, which provides transposase, is responsible for cointegration. Whenever the cointegrate plasmids were present in cells containing gamma-delta or its related transposon Tn3, the cointegrates were dissolved to give pBV320::IS101 due to recombination at duplicated IS101 sequences in the cointegrates, suggesting that both gamma-delta and Tn3, which provide a resolvase, are responsible for the resolution of the cointegrates. Comparison between the nucleotide sequence of IS101 and those of gamma-delta and Tn3 shows a high degree of homology in the regions that have been shown to be the binding sites of resolvases, as well as in the terminal inverted repeats. However, there is no homology between IS101 and the other element, gamma-delta or Tn3, in the internal resolution site, at which the resolution event may occur.

Ampicillin↗

PubMed1984

Evaluation of the cerebral vasculature by intraarterial DSA--with emphasis on in vivo resolution.

Comparative study was performed between IA DSA and stereoscopic magnification angiography in relation to small vessel resolution, image quality of the vessels and image quality of various pathologic lesions. The vessels of various diameters, accurately measured by stereoscopic magnification angiography, were localized on IA DSA and their resolution was carefully assessed. The vessels more than 1 mm in diameter were equally visualized on IA DSA and conventional angiography. The vessels between 1 mm and 0.5 mm showed fair resolution on IA DSA, whereas IA DSA did not resolve the vessels smaller than 0.5 mm in diameter to good advantage. In addition, image quality of the vessels on IA DSA was compared with the conventional methods. Cerebral gyrus, venous sinuses, and intracerebral veins are often shown better on DSA. The small vessels such as lenticulostriate, small cortical, thalamoperforate and meningohypophyseal arteries were not defined on DSA. Equal or better image quality was obtained in more than 85% of cases with pathologic lesions. Examinations were performed faster with lower cost and lower complication rate. Information provided by DSA was often sufficient for managements of patients. Combined use of DSA and conventional angiography will improve diagnostic accuracy and decrease the complication rate.

Brain Diseases↗