Diffraction enhanced imaging of controlled defects within bone, including bone-metal gaps.

Gap regions between a bone and an implant, whether existing upon insertion or developing over time, can lead to implant failure. Currently, planar x-ray imaging and CT are the most commonly used methods to evaluate the gap region. An alternative to these available clinical imaging modalities could help to better evaluate bone resorption. Previous experiments with diffraction enhanced imaging (DEI) have shown significant contrast advantages over monochromatic synchrotron radiation (SR) imaging. DEI and planar SR radiography images of bone samples with drill holes and gap regions of known geometry were acquired at the NSLS beamline X15A (Upton, NY, USA). The images acquired with DEI show measurable contrast-to-noise gains when compared to the images acquired using SR radiography.

The success of duplex ultrasonographic scanning in diagnosis of extremity vascular proximity trauma.

OBJECTIVE: To determine if duplex ultrasonographic scanning is diagnostically equivalent to arteriography and/or operative exploration in the diagnosis of extremity vascular proximity trauma. DESIGN: A prospective evaluation comparing duplex scanning with arteriography or operative exploration in 50 patients. Subsequently, duplex scanning was used alone for 175 extremity vascular proximity injuries, with other diagnostic methods used when injury was indicated on the duplex scan. SETTING: A busy urban trauma center. PATIENTS: Consecutive sample of 200 patients with 225 extremity injuries. SELECTION CRITERIA: Vascular proximity injury or diminished strength of the extremity pulse. MAIN OUTCOME MEASURES: The presence or absence of vascular proximity injury confirmed on angiography and/or operative exploration. RESULTS: Duplex scanning had 100% sensitivity and 100% specificity compared with arteriography and/or operative exploration in the first 50 cases. In the remaining 175 cases of extremity trauma, vascular injuries were diagnosed with duplex scanning alone. Duplex scanning detected 18 injuries, 17 of which were confirmed by correlation with arteriograms and/or operative exploration. One false-positive result--spasm of the superficial femoral artery--was found on arteriography. Seven unsuspected venous injuries were also diagnosed. CONCLUSIONS: Duplex scanning is a noninvasive, safe, effective method for the initial evaluation of potential extremity vascular proximity injury. It has replaced arteriography in the initial diagnosis of extremity vascular proximity trauma by our trauma service.

Diffraction enhanced imaging contrast mechanisms in breast cancer specimens.

We have investigated the contrast mechanisms of the refraction angle, and the apparent absorption images obtained from the diffraction enhanced imaging technique (DEI) and have correlated them with the absorption contrast of conventional radiography. The contrast of both the DEI refraction angle image and the radiograph have the same dependence on density differences of the tissues in the visualization of cancer; in radiography these differences directly relate to the contrast while in the DEI refraction angle image it is the density difference and thickness gradient that gives the refraction angle. We show that the density difference of fibrils in breast cancer as measured by absorption images correlate well with the density difference derived from refraction angle images of DEI. In addition we find that the DEI apparent absorption image and the image obtained with the DEI system at the top of the reflectivity curve have much greater contrast than that of the normal radiograph (x8 to 33-fold higher). This is due to the rejection of small angle scattering (extinction) from the fibrils enhancing the contrast.

Duplex scanning replaces arteriography and operative exploration in the diagnosis of potential cervical vascular injury.

BACKGROUND: The pursuit of a diagnosis is more aggressive in suspected cervical vascular injury than in extremity vascular proximity injury, since the complications of missing the neck injury may result in irreversible neurologic damage. Most institutions use arteriography and operative exploration, but these modalities identify only 10% of cervical vascular traumas. While duplex scanning is the screening test of choice for carotid occlusive disease, few published reports have described experience with this modality in cervical vascular trauma. PATIENTS AND METHODS: To determine if duplex scanning can replace arteriography or operative exploration as the initial screening modality in the assessment of potential cervical vascular trauma, we performed a prospective evaluation in two parts. First, we used duplex scanning and cervical arteriography, concomitantly, to rule out injury in 15 patients. We then used duplex scanning alone in 85 patients, reserving arteriography for cases in which the scan revealed an arterial injury. RESULTS: Duplex scans and arteriography and operation diagnosed cervical vascular trauma equally well. Eight injuries were identified in all areas of the cervical arterial tree. No duplex scans have been falsely negative or falsely positive. Use of duplex scans instead of arteriography saved $1,252 per case. CONCLUSIONS: Duplex scanning detects cervical vascular injuries as effectively as arteriography or operation, and is faster and less expensive. This approach expands the utility of diagnostic ultrasound in the evaluation of trauma patients. It has become the procedure of choice for diagnosing cervical vascular trauma at our institution.

Structural variations in soluble iron complexes of models for ferritin: an x-ray absorption and Mössbauer spectroscopy comparison of horse spleen ferritin to Blutal (iron-chondroitin sulfate) and Imferon (iron-dextran).

Variations in the turnover of storage iron have been attributed to differences in apoferritin and in the cytoplasm but rarely to differences in the structure of the iron core (except size). To explore the idea that the iron environment in soluble iron complexes could vary, we compared horse spleen ferritin to pharmaceutically important model complexes of hydrous ferric oxide formed from FeCl3 and dextran (Imferon) or chondroitin sulfate (Blutal), using x-ray absorption (EXAFS) and Mössbauer spectroscopy. The results show that the iron in the chondroitin sulfate complex was more ordered than in either horse spleen ferritin or the dextran complex (EXAFS), with two magnetic environments (Mössbauer), one (80%-85%) like Fe2O3 X nH2O (ferritinlike) and one (15%-20%) like Fe2O3 (hematite); since sulfate promotes the formation of inorganic hematite, the sulfate in the chondroitin sulfate most likely nucleated Fe2O3 and hydroxyl/carboxyls, which are ligands common to chondroitin sulfate, ferritin and dextran most likely nucleated Fe2O3 X nH2O. Differences in the structure of the iron complexed with chondroitin sulfate or dextran coincide with altered rates of iron release in vivo and in vitro and provide the first example relating function to local iron structure. Differences might also occur among ferritins in vivo, depending on the apoferritin (variations in anion-binding sites) or the cytoplasm (anion concentration).

A comparison of an undecairon(III) complex with the ferritin iron core.

The iron core of ferritin is comprised of up to 4,500 Fe(III) atoms as Fe2O3.nH2O, which is maintained in solution by a surrounding, spherical coat of protein. Organisms as diverse as bacteria and man use the ferritin iron-protein complex as a reservoir of stored iron for other essential proteins. To extend studies of the steps in polynuclear iron core formation, a recently characterized undecairon(III) oxo-hydroxo aggregate [Fe11 complex] (Gorun et al., J. Am. Chem. Soc. 109, 3337 [1987]) was examined by x-ray absorption spectroscopy as a model for an intermediate. The results, which are comparable to the previous x-ray diffraction studies, show near neighbors (Fe-O) at 1.90 A that are distinct from those in ferritin and a longer distance of 2.02 A. However, contributions from neighbors (Fe-C) known to exist at ca. 2.7 A were obscured by a highly ordered Fe-Fe interaction and were not detectable in the Fe11 complex in contrast to a previously characterized Fe(III) cluster bound to the protein coat. Of the two Fe-Fe interactions detectable in the Fe11 complex, the shortest, at 3.0 A is particularly interesting, occurring at the same distance as a full shell (CN = 6) in ferritin, but having fewer Fe neighbors (CN = 2-3) characteristic of an intermediate in core formation. The incomplete Fe-Fe shell is much more ordered than in ferritin, suggesting that the disorder in ferritin cores may be associated with the later steps of the core growth. Differences between the Fe11 complex and the full core of ferritin indicate the possibility of intermediates in ferritin iron formation that might be like Fe11.

The recharacterization of a polysaccharide iron complex (Niferex).

An oral hematinic marketed as "Niferex," the active component of which is a polysaccharide-iron complex (PIC), has recently been recharacterized. PIC is synthesized by the neutralization of an FeCl3 carbohydrate solution. Original characterization of this complex by Mössbauer spectroscopy and X-ray powder diffraction suggested that the iron-rich core was similar in structure to the mineral ferrihydrite. Higher precision X-ray powder diffraction now indicates that the core has a long-range order more similar to the mineral akaganéite, beta-FeOOH, than to ferrihydrite. This structure has been found for other similar ferric iron-carbohydrate polymers, especially those synthesized by the hydrolysis of FeCl3. Also discussed are the variable temperature (24-295 K) Mössbauer spectroscopic data for PIC. The first example of EXAFS data for polysaccharide iron complexes confirms that the iron is in an octahedral environment, coordinated to oxygen, with a short-range order similar to that for ferritin. The second iron shells in the PIC samples are less ordered than the second shell in ferritin. The size of the PIC core was found to be approximately 5 nm by X-ray powder diffraction, and is of the same order of magnitude as the ferritin core.

Diffraction enhanced x-ray imaging.

Diffraction enhanced imaging is a new x-ray radiographic imaging modality using monochromatic x-rays from a synchrotron which produces images of thick absorbing objects that are almost completely free of scatter. They show dramatically improved contrast over standard imaging applied to the same phantom. The contrast is based not only on attenuation but also the refraction and diffraction properties of the sample. This imaging method may improve image quality for medical applications, industrial radiography for non-destructive testing and x-ray computed tomography.

Stereociliary cross-links between adjacent inner hair cells.

An extensive network of intracellular cross-links occurs between the stereocilia of each cochlear hair cell bundle. These links fall into two main categories; lateral links which run roughly horizontal with respect to the reticular lamina and which join stereocilia of the same or adjacent rows, and tip-to-side links which run at a more vertical angle from the tip of each shorter stereocilium to the side of the adjacent longer stereocilium in the row behind. It has been proposed that deformation of the tip-to-side links causes alteration of the rate of opening of ion channels, producing transduction. Lateral linkages also occur between the stereocilia of adjacent hair cells. Now, intercellular links which resemble the tip-to-side links have been observed. Some of these occur in positions inappropriate to their proposed role in transduction. Several hypotheses are proposed to account for their presence e.g., the links could represent the remnants of a glycocalyx which is best preserved in areas where stereocilia are closely opposed.

Medical applications of diffraction enhanced imaging.

We have developed a new X-ray imaging technique, diffraction enhanced imaging (DEI), which can be used to independently visualize the refraction and absorption of an object. The images are almost completely scatter-free, allowing enhanced contrast of objects that develop small angle scattering. The combination of these properties has resulted in images of mammography phantoms and tissues that have dramatically improved contrast over standard imaging techniques. This technique potentially is applicable to mammography and other fields of medical X-ray imaging and to radiology in general, as well as possible use in nondestructive testing and X-ray computed tomography. Images of various tissues and materials are presented to demonstrate the wide applicability of this technique to medical and biological imaging.

When caring leaves bruises: the effects of staff education on resident aggression.

1. Physical aggression toward nursing staff by confused elderly residents is a very common and frustrating clinical nursing problem in long-term care facilities. 2. Some physical aggression may be associated with a lack of knowledge about dementia, therefore staff inservice education may be one way of reducing some forms of physical aggression. 3. The authors found a 50% reduction in reported physical aggression from elderly residents after a staff education program on dementia and aggression was implemented.

[Concentration of heavy elements and their compounds in the cells from BALF and pulmonary tumors in radiation-exposed subjects]. / Soderzhanie tiazhelykh élementov i ikh soedinenii v kletkakh bronkhoaal'veoliarnykh smyvov i v tkaniakh opukholei legkikh u lits, podvergavshikhsia radiatsionnomu vozdeistviiu.

AIM: Measurement of heavy elements in alveolar macrophages (AM) of bronchoalveolar lavage (BAL) and pulmonary tumor tissue (PTT); investigation of spacial distribution of the heavy particles in the tissues. MATERIALS AND METHODS: Laser mass-spectrometry estimated quantitative and qualitative characteristics of heavy elements (Mn, Fe, Co, Cu, Zr, etc.) in diagnostic and therapeutic BAL of 6 patients exposed to radiation after the Chernobyl accident and in pulmonary tumor tissue of patients operated for central small-cell and peripheral bronchoalveolar cancer who also had been exposed to radiation after the Chernobyl. RESULTS: Heavy elements concentration in the secondary BAL was less than in the primary one. This shows effectiveness of the procedures aimed at removal of heavy particles from the respiratory organs. Heavy elements content was quite different in two histologically different tumors. CONCLUSION: Laser mass-spectrometry proved its usefulness in simultaneous study of the quantity and quality of heavy elements in AM of BAL and tumors in radiation-exposed subjects, in investigation of the elements distribution in the pulmonary tissues and changes of elements composition in the tissues in the course of tumors development.

Similarity of the structure of ferritin and iron . dextran (imferon) determined by extended X-ray absorption fine structure analysis.

Ferritin, a natural complex of iron oxide encased in protein, and iron . dextran, a synthetic complex of iron oxide coated with dextran, have the similar properties of maintaining high concentrations of iron in solution at physiological pH and releasing iron relatively slowly in vivo. Extended x-ray absorption fine structure (EX-AFS) analysis was performed on each complex and compared to see if the structures of the iron cores were similar. The results obtained from the extended x-ray absorption fine structure technique show that the near-neighbor environment around the average iron atom in ferritin and iron . dextran is identical, within experimental uncertainty, for the first three shells. The similarity of the iron cores in both complexes may explain the similarity of iron release in vivo. Ferritin has a protein coat which is composed of 24 subunits arranged in a hollow sphere with six channels through which the iron may move during deposition and release. However, little is known about the requirements of the protein structure in ferritin for the maintenance of high concentrations of iron in a soluble, nontoxic form or about the role of the protein in the release of iron from ferritin. The results suggest that iron . dextran will be a useful model compound in studies of the relation of the iron core and protein in ferritin to function.

A distinct environment for iron (III) in the complex with horse spleen apoferritin observed by x-ray absorption spectroscopy.

Cell-specific variations in apoferritin structure correlate with variations in iron metabolism that suggest functional specificity of the protein shell. Using EPR spectroscopy, we previously showed that vanadyl binds to specific sites on apoferritin, and that VO2+ binding is reduced by Fe(II) and Fe(III) (the natural substrates) and by metals known to influence iron storage (Chasteen, N. D., and Theil, E. C. (1982) J. Biol. Chem. 257, 7672-7677). Such observations suggest that the metal-binding site is important to apoferritin function and may define a location where the influence of cell-specific structural features are exerted. To investigate the iron-protein complex further, we have used x-ray absorption spectroscopy and have characterized, for the first time to our knowledge, Fe(III) apparently attached to the protein, after analyzing the x-ray absorption spectrum of an Fe(III)-apoferritin complex (10 Fe/molecule) compared to that of ferritin (polynuclear Fe(III)OOH, about 2000/molecule). The environment of iron in the Fe(III)-protein complex was similar to that in an Fe(III)-oxalate (2:3) hexahydrate complex, both in near edge structure and extended x-ray absorption structure, confirming earlier predictions of carboxylates as protein ligands. The extended x-ray absorption fine structure data for both compounds was fit best by a model in which a second shell of low Z atoms (carbon) was close (0.53-0.55 A) to the first shell of coordinated oxygen. However, small differences between Fe(III)-apoferritin and Fe(III)-oxalate in the Fe-O environment suggest a distorted geometry in the Fe(III)-protein complex and/or the presence of a mixture of atoms, such as nitrogen and oxygen, coordinated to iron. Extension of this approach to other apoferritins and metals will be likely to clarify the role of cell-specific features of the apoprotein in the formation of the iron core.

The demonstration of bone and cartilage remodelling using alcian blue and hematoxylin.

A new staining technique based on alcian blue and hematoxylin was used during the study of experimentally produced fractures in long bone. The distinction between cartilage, woven bone, mature bone and necrotic bone during successive stages of the fracture healing process was particularly remarkable. This method was found also to be very useful in the study of general tissue morphology. It is suggested that this postdecalcification light microscopy staining method is suitable for studies of cartilage and bone development with particular reference to ossification, remodelling and bone pathology.

Cervical spine flexion patterns.

Lateral projection flexion and extension radiographs of the cervical spine are stress views. They are necessary to evaluate unstable ligamentous injury, which may not be apparent on neutral unstressed films. As there is very little literature on the proper evaluation of these radiographic views, we reviewed 150 consecutive cases from our Emergency Department to define patterns of flexion. Four significantly different patterns emerged. No flexion at any level was seen in 24.7% of patients. A single flexion angle was seen in 24.7% Two flexion angles, usually at consecutive levels, were present in 29.3% of patients, and 21.3% had three or more flexion angles. Correlation with clinical data suggests that attempted flexion with no significant angle or a single angle is abnormal and may indicate soft tissue (ligament or muscle) injury. Three or more flexion angles are thought to represent a normal pattern. The most common pattern, two flexion angles at consecutive levels, has not been previously described. We believe this pattern indicates less than full flexion and can be seen in individuals without significant injury and in those limited by mild soft-tissue injury.

Fe(III).ATP complexes. Models for ferritin and other polynuclear iron complexes with phosphate.

Polynuclear iron complexes of Fe(III) and phosphate occur in seawater and soils and in cells where the iron core of ferritin, the iron storage protein, contains up to 4500 Fe atoms in a complex with an average composition of (FeO.OH)8FeO.OPO3H2. Although phosphate influences the size of the ferritin core and thus the availability of stored iron, little is known about the nature of the Fe(III)-phosphate interaction. In the present study, Fe-phosphate interactions were analyzed in stable complexes of Fe(III).ATP which, in the polynuclear iron form, had phosphate at interior sites. Such Fe(III).ATP complexes are important not only as models but also because they may play a role in intracellular iron transport and in iron toxicity; the complexes were studied by extended x-ray absorption fine structure, EPR, NMR spectroscopy, and measurement of proton release. Mononuclear iron complexes exhibiting a g' = 4.3 EPR signal were formed at Fe:ATP ratios less than or equal to 1:3, and polynuclear iron complexes (Fe greater than or equal to 250, EPR silent at g' = 4.3) were formed at an Fe:ATP ratio of 4:1. No NMR signals due to ATP were observed when Fe was in excess (Fe:ATP = 4:1). Extended x-ray absorption fine structure analysis of the polynuclear Fe(III).ATP complex was able to distinguish an Fe-P distance at 3.27 A in addition to the octahedral O at 1.95 A and 4-5 Fe atoms at 3.36 A. The Fe-O and Fe-Fe distances are the same as in ferritin, and the Fe-P distance is analogous to that in another metal-ATP complex. An observable Fe-P environment in such a large polynuclear iron cluster as the Fe(III).ATP (4:1) complex indicates that the phosphate is distributed throughout rather than merely on the surface, in contrast to earlier models of chelate-stabilized iron clusters. Complexes of Fe(III) and ATP similar to those described here may form in vivo either as normal components of intracellular iron metabolism or during iron excess where the consequent alteration of free nucleotide triphosphate pools could contribute to the observed toxicity of iron.

In situ studies of metal-semiconductor interactions with synchrotron radiation.

The capabilities and performance of a UHV system for in situ studies of metal-semiconductor interactions are described. The UHV system consists of interconnected deposition and analysis chambers, each of which is capable of maintaining a base pressure of approximately 1 x 10(-10) torr. The deposited materials and their reaction products can be studied in situ with RHEED, XAFS, AES, XPS, UPS and ARUPS. Results from a study of the reaction of 0.7- and 1.7-monolayer-thick films of cobalt with strained silicon-germanium alloys are presented. The signal-to-noise ratio obtained in these experiments indicates that the apparatus is capable of supporting in situ EXAFS studies of approximately 0.1-monolayer-thick films.