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Multifocal vascular lesions of bone: imaging characteristics.

OBJECTIVE: Multifocal vascular processes which arise in bone are a very inhomogeneous class of diseases. Four of these processes are derived from endothelial precursors, however, and share a similar radiographic spectrum. These four entities are reviewed in order to clarify their imaging patterns and the diagnostic utility of imaging modalities. METHODS: Eight cases of cystic angiomatosis, multifocal hemangioma, hemangioendothelioma and angiosarcoma presenting to a tertiary referral center over a 7-year period were reviewed. The medical literature was also reviewed for information concerning the imaging of these processes. RESULTS: All four diseases produced radiolucent defects on plain radiographs with variable margination reflecting the aggressiveness of the lesions. Computed tomography was used to examine five patients and provided supportive, though generally non-diagnostic, information in the five cases in which it was performed. Radionuclide bone scintigraphy, as reported in the literature, underestimated the extent of skeletal involvement in all eight cases, though some lesions were identified. Radionuclide imaging with labeled red blood cells, performed in three cases, did not add any information, which is contrary to some reports in the literature. Magnetic resonance imaging proved the most sensitive for identifying lesions, although the imaging characteristics were not diagnostic. CONCLUSIONS: Plain radiographs are the mainstay for imaging multifocal endothelial processes. Radiographs provide information on aggressiveness, multifocality and distribution of lesions. Computed tomography provides similar information. Magnetic resonance imaging often detects additional lesions. The insensitivity of radionuclide bone scintigraphy is surprising. Reports of unique deposition of radionuclide in tagged red blood cell scanning has been reported to support the diagnosis of vascular lesions, but it did not do so in these cases.

Adolescent↗

Chylomicron and VLDL TAG structures and postprandial lipid response induced by lard and modified lard.

Alterations in chylomicron and VLDL TAG and the magnitude of postprandial lipemia were studied in healthy volunteers after two meals of equal FA composition but different TAG FA positional distribution. Molecular level information of individual lipoprotein TAG regioisomers was obtained with a tandem MS method. The incremental area under the response curve of VLDL TAG was larger (P = 0.021) after modified lard than after lard. In plasma TAG, the difference did not quite reach statistical significance (P = 0.086). In general, there were less TAG with palmitic acid in the sn-2 position and more TAG with oleic acid in the sn-2 position in chylomicrons than in fat ingested. From 1.5 to 8 h postprandially, the proportion of individual chylomicron TAG was constant or influenced by TAG M.W. VLDL TAG regioisomerism was similar regardless of the positional distribution of fat ingested. Significant alterations were seen in VLDL TAG FA, in M.W. fractions, and in individual regioisomers with respect to time. The TAG sn-14:0-18:1-18:1 + sn-18:1-18:1-14:0, sn-16:0-16:1-18:1 + sn-18:1-16:1-16:0, and sn-16:1-18:1-18:1 + sn-18:1-18:1-16:1 decreased (P < 0.05); and sn-16:0-16:0-18:2 + sn-18:2-16:0-16:0, sn-16:0-16:0-18:1 + sn-18:1-16:0-16:0, sn-16:0-18:1-16:0, and sn-16:0-18:1-18:2 + sn-18:2-18:1-16:0 increased (P < 0.05) after both meals. In conclusion, positional distribution of TAG FA was found to affect postprandial lipid metabolism in healthy normolipidemic subjects.

Adult↗

Two-dimensional mitral flow velocity profiles in pig models using epicardial Doppler echocardiography.

OBJECTIVES: This study investigated the velocity distribution across the natural mitral valve. BACKGROUND: Information about the blood velocity distribution across the mitral valve is of interest in basic fluid dynamic studies of the natural mitral valve and is needed for precise cardiac output estimates by Doppler echocardiography. METHODS: The velocity distribution across the mitral valve was measured by epicardial Doppler echocardiography in ten 90-kg anesthetized pigs. By rotating the ultrasound transducer in 30 degrees intervals from the apical position, we constructed two-dimensional velocity profiles across the left ventricular inflow tract from diameters from each rotation arranged around a reference point. The time-averaged mitral velocity profile was calculated to estimate the error in cardiac output calculations that may occur with pulsed Doppler ultrasound when a single sample volume is used to record the mean velocity across the mitral orifice. RESULTS: The time-averaged diastolic cross-sectional mitral velocity profiles at the level of the mitral annulus and leaflet tips were variably skewed because of the development of a large anterior vortex in the left ventricle during the deceleration of early diastolic inflow and atrial systole. The ratio of the time-velocity integral of the center sample volume to the spatially averaged time-velocity integral was 1.13 +/- 0.15 (mean +/- SD) (range 0.80 to 1.32). Using regression analysis, we found a correlation between the degree of nonuniformity of the cross-sectional velocity distribution and the peak velocity of the anterior vortex (r = 0.65, p < 0.01). CONCLUSIONS: The assumption of a flat mean velocity profile across the mitral valve can introduce errors of +13 +/- 15% (mean +/- SD) in cardiac output measured with pulsed Doppler ultrasound when one is interrogating a single center sample volume.

Animals↗

An assessment of vulval pigmentation.

Thirty-five vulvectomy specimens were obtained from post-mortem material and studied to assess the distribution of melanin pigment. The information obtained was compared with the melanin distribution in melanoma-in-situ and melanosis vulvae. A lesion had to be larger than 3mm before it was recognised clinically. Melanosis vulvae is but an exaggeration of the normal distribution of melanin pigment. Melanoma-in-situ, however, cannot be reliably distinguished from the benign causes of pigmentation on clinical grounds. The correct diagnosis can only be made histologically. Other causes of vulval pigmentation are also discussed.

Aged↗

Ordered distribution of membrane-associated dense plaques in intact quail gizzard smooth muscle cells revealed by freeze-fracture following treatment with cholesterol probes.

The surface distribution of membrane-associated dense plaques in intact quail gizzard smooth muscle cells was investigated by freeze-fracture. Replicas of fractured smooth muscle cell plasma membrane showed caveola-free regions with few intramembrane particles, interspersed with caveola-populated areas with a higher intramembrane particle density. Electron microscopy of thin sections of quail gizzard smooth muscle revealed the regions free of caveolae to be occupied by membrane-associated dense plaques; anchoring sites for the contractile filaments of the cell. Demarcation between the caveola-populated and caveola-free regions on the relicated intramembrane surface was not clear and thus provided little information concerning the distribution of dense plaque sites. However, treatment of the smooth muscle tissue with the cholesterol-binding agents filipin or tomatin prior to freeze-fracture allowed the dense plaque sites to be easily observed as the sites remained free of the membrane deformations characteristic of these agents. The dense plaque sites consist of caveola-free oval areas juxtaposed in regular bands that traverse the long axis of the cell. The dense plaque sites on the freeze-fracture replica were confirmed by electron microscopy of thin sections of filipin-treated quail gizzard smooth muscle cells, which showed the plasma membrane associated with the dense plaques to be unaffected by the actions of filipin, whereas that of the caveola-populated region was severely deformed. The observations presented in this study provide evidence for a highly ordered distribution of dense plaques at the cell surface of intact quail gizzard smooth muscle cells and thus corroborate existing evidence for an organized substructure of smooth muscle cells.

Animals↗

Fluorescence imaging of tracer distributions in soil profiles.

To evaluate and parametrize transport models for the vadose (partially water-unsaturated) zone, information about the spatial distributions of solutes is needed. We describe a technique for the simultaneous imaging of several fluorescent tracers in structured field soils. With this technique, we obtain information on local mixing under field conditions. Local dispersion is a decisive process that discriminates different flow regimes. The imaging device consists of a high-power xenon lamp and a sensitive charge coupled device (CCD) camera. The three fluorescent dyes Brilliant sulfaflavine (BF), Sulforhodamine B (SB), and Oxazine 170 (OX) were chosen as solute tracers for their spectroscopic properties and different sorption coefficients. We conducted a field experiment using these tracers and took images of their distribution in a vertical soil profile. The fluorescence images (1242 by 1152 pixels) were corrected for nonuniform lighting, changing surface roughness, and varying optical properties of the soil profile. The resulting two-dimensional relative concentration distributions were similar for BF and SB. The reason might be the fast transport regime, which prevents the establishment of sorption equilibria. According to its higher sorption coefficient, OX was more strongly retarded. In this paper, we show that the fluorescence imaging technique is a powerful tool for the in-situ investigation of transport processes of fluorescent solute tracers in soil profiles. Due to the high spatial resolution of the tracer concentration maps and the ability to detect the flow field characteristics of differently reactive tracers simultaneously under field conditions, this technique provides valuable experimental data for the test and development of theoretical models for heterogeneous solute transport in soils.

Adsorption↗

White matter mapping in Alzheimer's disease: A neuropathological study.

White matter disease (WMD) with pervasive non-focal subtotal tissue loss is frequently seen in Alzheimer's disease (AD) upon neuropathological examination. Although WMD has varying effects on AD symptoms, accurate clinical detection is difficult due partly to scarcity of correlative structural imaging and histopathological studies. Neuropathological studies of WMD severity and distribution have been conducted earlier using semi-quantitative methods. A technique for quantifying WMD objectively in large white matter areas, based on optical density (OD) measurements on images of scanned whole-brain sections, was developed and was validated using conventional microscopic assessment. Altogether, 16 AD cases with concomitant WMD (AD-WMD) and 9 cases of AD without WMD (AD-only) were analysed. The OD values correlated significantly with the neuropathological severity of WMD and were significantly lower in AD-WMD than in AD-only in frontal, frontoparietal, temporal and parietal white matter but not in the occipital white matter, the frontal OD difference being greatest. Useful baseline information on WMD distribution in AD to relate to in vivo imaging results was obtained.

Aged↗

The distribution of bovine trypanosomosis in Zimbabwe and an evaluation of the value of an anti-trypanosomal antibody detection ELISA as a tool for monitoring the effectiveness of tsetse control operations.

Tsetse have been cleared from large areas of Zimbabwe during the past 65 years. In most areas, they are prevented from re-invading cleared areas by barriers of odour-baited, insecticide-treated targets. A trypanosomosis survey was conducted to determine the effectiveness of such barriers against re-invasion and to confirm the absence of tsetse in areas where they had previously been eradicated. Parasitological diagnostic methods and an anti-trypanosomal antibody detection enzyme-linked immunosorbent assay (antibody ELISA) were used. The prevalence of trypanosomal infections in the tsetse-cleared areas was generally low. However, the prevalence of anti-trypanosomal antibodies was unexpectedly high in some areas. This high proportion of cattle with antibodies could, in most cases, be explained by recent or historic information on the distribution and density of tsetse. The results from the survey demonstrated the value of anti-trypanosomal antibody detection as an additional sensitive tool for monitoring the effectiveness of tsetse control operations.

Animals↗

The geography of sexual partnerships in Baltimore: applications of core theory dynamics using a geographic information system.

OBJECTIVE: Gonorrhea has a focused geographic distribution characterized by high incidence rates in defined "core" areas and decreased incidence as the radial distance from the central core increases. Dense cor group transmission has long been hypothesized. METHODS: We have previously mapped sexually transmitted disease (STD) rates in Baltimore census tracts using STD morbidity data interfaced with a geographic information system. Core areas were defined using a standard definition based on gonorrhea distribution. We studied spatial distance patterns between sexual partners, using the residential addresses of 572 individuals, representing 286 dyad partnerships recruited as part of an epidemiology and behavioral study. To determine if partners lived closer together than would be expected, a modified bootstrap algorithm using Monte Carlo models was developed to compare the distances between partners' residences and all other possible residences. RESULTS: Two distinct (east and west) core areas were previously identified. Compared with randomly selected Baltimore addresses, partners tended to reside closer to one another than would be expected by chance (z = -1.8), with a median distance of 1.7 kilometers. Within the core areas, women resided a median of 547 meters from their partner, and men resided a median of 339 meters from their reported partners. When all partnerships were considered, the median distance was 1,699 meters. Of the 500 simulation models, the minimum median distance was 4,889 meters. CONCLUSIONS: Partners of patients in core areas in Baltimore live remarkably close to one another, and the partner selection patterns in general indicate nonrandom distribution. Geographic information system-determined patterns of STD patients residing in hyperendemic census tracts support the core theory of disease transmission. In these areas, targeted geographically based interventions may be warranted.

Adult↗

Structure of star-burst dendrimers: a comparison between small angle x-ray scattering and computer simulation results.

We investigated the generation dependent shape and internal structure of star-burst dendrimers under good solvent conditions using small angle x-ray scattering and molecular modeling. Measurements have been performed on poly(amidoamine) dendrimers with generations ranging from g=0 up to g=8 at low concentrations in methanol. We described the static form factor P(q) by a model taking into account the compact, globular shape as well as the loose, polymeric character of dendrimers. Monomer distributions within dendrimers are of special interest for potential applications and have been characterized by the pair correlation function gamma(r), as well as by the monomer and end-group density profile, rho(r) and rho(e)(r), respectively. Monomer density profiles and gamma(r) can be derived from P(q) by modeling and via a model independent approach using the inverse Fourier transformation algorithm first introduced by Glatter. Experimental results are compared with computer simulations performed for single dendrimers of various generations using the cooperative motion algorithm. The simulation gives direct access to gamma(r) and rho(r), allows an independent determination of P(q), and yields in addition to the scattering experiment information about the distribution of the end groups. Excellent qualitative agreement between experiment and simulation has been found.

Journal Article↗

Determination of IgE antibodies to Polistes dominulus, Vespula germanica and Vespa crabro in sera of patients allergic to vespids.

The study was undertaken to investigate the presence of IgE antibodies to Polistes dominulus (PD), Vespula germanica (VG) and Vespa crabro (VC) in a large group of sera belonging to patients sensitized to Vespids in Spain. RAST values showed that although the majority of patients had IgE antibodies to PD, VG and VC, there was a marked predominance of PD. These results were related to the distribution of the insect in the areas where the sera were obtained. Due to geographical and insect distribution differences, the whole area was divided into three zones: Central, East and South. Comparison of the positive RAST values obtained indicated that, although the positivity to PD predominated over VG and this over VC, there were significant differences in percentage positivities to each vespid in the different regions studied. The results of the RAST absorption studies indicated that in most instances patients were originally sensitized to one vespid and were RAST positive to the other venoms due to cross-reactivity. Only in a minority of cases were coexisting antibodies to two insects present. These results show that PD and VG are the important vespids followed to a lesser extent by VC. This study provides relevant information concerning insect distribution sensitivity in a European country.

Animals↗

Depo-Provera--ethical issues in its testing and distribution.

Ethical issues relating to the use of the injectable contraceptive in developed and developing countries alike involve public policy decisions concerning both criteria for testing a new drug and individual choices about using a specific form of contraception approved for national distribution. Drug testing consists of an important but still evolving set of procedures. Depo-Provera is not qualitatively different from any other drug and some unpredictable risks are inevitable, even after extensive animal experiments and clinical trials. In assessing the risks and benefits of Depo-Provera use, epidemiological data from large-scale human use is now beginning to become more important than data from animal experiments and clinical trials. The consumer's best interest is central to any ethically responsible system of drug distribution. Systems of informed choice are needed, even in societies where illiteracy remains common and medical services are weak. In the case of a contraceptive, the risks of non-use leading to unintended pregnancy, which can result in high mortality, are relevant as well as the side-effects of the method. An attempt, therefore, is made here to categorise those issues which are universal and those which are country-specific.

Contraceptive Agents, Female↗

MolTalk--a programming library for protein structures and structure analysis.

BACKGROUND: Two of the mostly unsolved but increasingly urgent problems for modern biologists are a) to quickly and easily analyse protein structures and b) to comprehensively mine the wealth of information, which is distributed along with the 3D co-ordinates by the Protein Data Bank (PDB). Tools which address this issue need to be highly flexible and powerful but at the same time must be freely available and easy to learn. RESULTS: We present MolTalk, an elaborate programming language, which consists of the programming library libmoltalk implemented in Objective-C and the Smalltalk-based interpreter MolTalk. MolTalk combines the advantages of an easy to learn and programmable procedural scripting with the flexibility and power of a full programming language. An overview of currently available applications of MolTalk is given and with PDBChainSaw one such application is described in more detail. PDBChainSaw is a MolTalk-based parser and information extraction utility of PDB files. Weekly updates of the PDB are synchronised with PDBChainSaw and are available for free download from the MolTalk project page http://www.moltalk.org following the link to PDBChainSaw. For each chain in a protein structure, PDBChainSaw extracts the sequence from its co-ordinates and provides additional information from the PDB-file header section, such as scientific organism, compound name, and EC code. CONCLUSION: MolTalk provides a rich set of methods to analyse and even modify experimentally determined or modelled protein structures. These methods vary in complexity and are thus suitable for beginners and advanced programmers alike. We envision MolTalk to be most valuable in the following applications:1) To analyse protein structures repetitively in large-scale, i.e. to benchmark protein structure prediction methods or to evaluate structural models. The quality of the resulting 3D-models can be assessed by e.g. calculating a Ramachandran-Sasisekharan plot.2) To quickly retrieve information for (a limited number of) macro-molecular structures, i.e. H-bonds, salt bridges, contacts between amino acids and ligands or at the interface between two chains.3) To programme more complex structural bioinformatics software and to implement demanding algorithms through its portability to Objective-C, e.g. iMolTalk.4) To be used as a front end to databases, e.g. PDBChainSaw.

Artificial Intelligence↗

Gap junctions in vascular tissues. Evaluating the role of intercellular communication in the modulation of vasomotor tone.

Integration and coordination of responses among vascular wall cells are critical to the local modulation of vasomotor tone and to the maintenance of circulatory homeostasis. This article reviews the vast literature concerning the principles that govern the initiation and propagation of vasoactive stimuli among vascular smooth muscle cells, which are nominally the final effectors of vasomotor tone. In light of the abundance of new information concerning the distribution and function of gap junctions between vascular wall cells throughout the vascular tree, particular attention is paid to this integral aspect of vascular physiology. Evidence is provided for the important contribution of intercellular communication to vascular function at all levels of the circulation, from the largest elastic artery to the terminal arterioles. The thesis of this review is that the presence of gap junctions, in concert with the autonomic nervous system, pacemaker cells, myogenic mechanisms, and/or electrotonic current spread (both hyperpolarizing and depolarizing waves through gap junctions), confers a plasticity, adaptability, and flexibility to vasculature that may well account for the observed diversity in regulation and function of vascular tissues throughout the vascular tree. It is hoped that the summary information provided here will serve as a launching pad for a new discourse on the mechanistic basis of the integrative regulation and function of vasculature, which painstakingly accounts for the undoubtedly complex and manifold role of gap junctions in vascular physiology/dysfunction.

Animals↗

Heavy metal sequential extraction methods--a modification for tropical soils.

Sequential extractions of metals can be useful to study metal distributions in various soil fractions. Although several sequential extraction procedures have been suggested in the literature, most were developed for temperate soils and may not be suitable for tropical soils with high contents of Mn and Fe oxides. The objective of this study was to develop a sequential fractionation procedure for Cu and Zn in tropical soils. Extractions were performed on surface (0-20 cm) samples of ten representative soils of Sao Paulo State, Brazil. Chemically reactive Mn forms were satisfactorily assessed by the new modified procedure. Amorphous and crystalline Fe oxides were more selectively extracted in a new two-step extraction. Soil-born Zn and Cu were primarily associated with recalcitrant soil fractions. The proposed procedure provided more detailed information on metal distribution in tropical soils and better characterization of the various components of the soil matrix. The new procedure is expected to be an important tool for predicting the potential effects of environmental changes and land application of metals on the redistribution of chemical forms of metals in tropical soils.

Copper↗

[Biomedical information networks: the experience of the United States National Library of Medicine].

A rapid and intensive flow of biomedical information is perceived increasingly as a requirement for the advancement of research, professional training, and the delivery of health services to an ever-growing human population. This article examines the concept of a network of information and cooperative services among medical libraries and national, regional and international data banks to maximize the sharing and use of the available resources. The background and record of the National Library of Medicine of the United States, which established the MEDLARS System, are described as a model for guidance. Since the end of the 19th century, when J. S. Billings, the foresighted first director of the Library, devised the first system for the indexing of medical literature, new techniques have been introduced step by step to facilitate the dissemination of biomedical information: mechanization and automatization of the placement of requests and data retrieval, telecommunications and satellite links to the fifteen data banks currently accessible to the user by direct communication through MEDLINE. For such a network to operate successfully, there must be a shift from the idea of regional or national benefit to the plane of global cooperation, through which a higher degree of self-sufficiency can be achieved. Also, relations between the various levels of the system must be based on a collaboration in which each entity pursues its own function subject to the character and multifarious scope of the common purposes. The success of BIREME in Latin America is cited as an incentive to developing countries to participate in the use and distribution of vital information through activities based on individual priorities without forgetting that what is important is not ideals and abstractions, but the human being with his needs, problems and real situation.

History, 19th Century↗

Chemical shift correlations in disordered solids.

We show how two-dimensional chemical shift conditional probability distributions can be extracted from experimental NMR correlation spectra of disordered solids. We show that transverse dephasing times are of central importance in determining the resolution (and sensitivity) of these probability distributions. These conditional probability distributions provide a new source of structural information characteristic of disordered solids, which is much more sensitive to structure than the individual-atom chemical shift distributions. The structural information contained in these distributions is clearly a potentially extremely rich source for understanding disorder. This is illustrated with examples of a phosphorus-containing organic compound and with a sample of disordered cellulose where the different structural allomorphs present are identified from the distributions.

Cellulose↗

Speciation of tissue and cellular iron with on-line detection by inductively coupled plasma-mass spectrometry.

Iron accumulating to excess in tissues of humans and animal models occurs mainly as complexes with transferrin, ferritin, other hemoproteins, and insoluble hemosiderin particles. To determine the distribution of Fe amongst these molecular species, we have used inductively coupled plasma-mass spectrometry as a means of on-line, isotope-specific detection for their liquid chromatographic separation. The stable isotope 57Fe is a suitable isotope for monitoring the Fe content of each fraction, and its availability at high isotopic enrichment makes it an attractive choice for tracer studies when the use of a radioisotope is undesirable, e.g., in human subjects. The detection system offers the advantages of high sensitivity (detection limits in the parts per billion range), a wide dynamic range (linearity of the calibration curve over several orders of magnitude), and on-line analysis facilitating real-time evaluation of the chromatographic separation, in addition to isotope-specific information. The Fe distributions in healthy rat livers, liver and heart tissue from Fe-loaded human subjects, and human hepatocyte cultures are reported. The ferritin:hemosiderin ratio in these samples is shown to be an indicator of the degree of Fe loading and correlates well with that determined by Zeeman-corrected electrothermal atomic absorption as an alternative means of detection.

Animals↗