Common femoral arterial access and arteriography in infants: Principles, pearls, and pitfalls

Infant femoral arterial access is an essential part of interventional procedures, hemodynamic monitoring, and support of critically ill patients. Due to small luminal diameter, superficial location, mobility, and increased risk of vasospasm, dissection, and thrombosis, femoral artery access in the infant is a technically demanding procedure. The purpose of this manuscript is to describe an approach to successful common femoral arterial access and arteriography in infants including common pearls and pitfalls.

Semi-automatic segmentation and surface reconstruction of computed tomography images by using rotoscoping and warping techniques

BACKGROUND

Quick and large-scale segmentation along with three-dimensional (3D) reconstruction is necessary to make precise 3D musculoskeletal models for surface anatomy education, palpation training, medical communication, morphology research, and virtual surgery simulation. However, automatic segmentation of the skin and muscles remain undeveloped.

MATERIALS AND METHODS

Therefore, in this study, we developed workflows for semi-automatic segmentation and surface reconstruction, using rotoscoping and warping techniques.

RESULTS

The techniques were applied to multi detector computed tomography images, which were optimised to quickly generate surface models of the skin and the anatomical structures underlying the fat tissue.

CONCLUSIONS

The workflows developed in this study are expected to enable researchers to create segmented images and optimised surface models from any set of serially sectioned images quickly and conveniently. Moreover, these optimised surface models can easily be modified for further application or educational use.

Coordination Polymers for High-Capacity Li-Ion Batteries: Metal-Dependent Solid-State Reversibility

Electrode materials exploiting multielectron-transfer processes are essential components for large-scale energy storage systems. Organic-based electrode materials undergoing distinct molecular redox transformations can intrinsically circumvent the structural instability issue of conventional inorganic-based host materials associated with lattice volume expansion and pulverization. Yet, the fundamental mechanistic understanding of metal-organic coordination polymers toward the reversible electrochemical processes is still lacking. Herein, we demonstrate that metal-dependent spatial proximity and binding affinity play a critical role in the reversible redox processes, as verified by combined ¹³C solid-state NMR, X-ray absorption spectroscopy, and transmission electron microscopy. During the electrochemical lithiation, in situ generated metallic nanoparticles dispersed in the organic matrix generate electrically conductive paths, synergistically aiding subsequent multielectron transfer to π-conjugated ligands. Comprehensive screening on 3d-metal-organic coordination polymers leads to a high-capacity electrode material, cobalt-2,5-thiophenedicarboxylate, which delivers a stable specific capacity of ∼1100 mA h g^-1 after 100 cycles.

Sectioned images and surface models of a cadaver for understanding the free vascularised anterior rib flap

BACKGROUND

The purpose of this study is to describe the vascularised anterior rib flap on sectioned images and surface models using Visible Korean for medical education and clinical training in the field of mandibular reconstructive surgery.

MATERIALS AND METHODS

Serially sectioned images of the thorax were obtained from a cadaver. Significant structures in the sectioned images were outlined and stacked to create a surface model.

RESULTS

The PDF file (8.45 MB) of the assembled models can be downloaded for free from our website (http://vkh.ajou.ac.kr/Products/PDF/Vascularized_anterior_rib_flap.zip). In this file, important anatomical structures related to the vascularised anterior rib flap can be examined in the sectioned images. All surface models and stereoscopic structures of the vascularised anterior rib flap are expressed in real time.

CONCLUSIONS

We hope that these state-of-the-art sectioned images, outlined images, and surface models will help students and trainees gain a better understanding of the anatomy of the vascularised anterior rib flap.

Organic-Catholyte-Containing Flexible Rechargeable Lithium Batteries

Organic-catholyte-containing flexible rechargeable lithium batteries are developed using fused cyclic quinone derivatives. The structural dependence of the quinone isomers in the liquid catholyte is studied using a combined experimental and theoretical approach. Stable electrochemical performance even under severe bending/stretching deformations is successfully demonstrated by prototype batteries containing liquid catholytes.

Segmentation and surface reconstruction of a cadaver heart on Mimics software

The Visible Korean research team used Mimics software (Materialise, Leuven, Belgium) for the segmentation and subsequent surface reconstruction of heart structures using information obtained from sectioned images of a cadaver. Twenty-six heart components were outlined in advance on Photoshop (Adobe Systems, San Jose, CA, USA). By use of the Mimics, the outlined images were then browsed along with the vertical planes as well as the 3-dimensional surface models, which were immediately built by piling the images. Erroneous delineation was readily detected and revised until satisfactory heart models were acquired. The surface models and the selected sectioned images in horizontal, coronal, and sagittal planes were inputted into a PDF file, where any combinations of reconstructed constituents could be displayed and rotated by the user. Mimics software accelerated the segmentation and surface reconstruction of heart anatomical structures. Similar benefits hopefully result from various serial images of other organs. The PDF file, and plane and stereoscopic image data are being distributed to others, and should prove valuable for medical students and clinicians.

Investigation of bioequivalence of a new fixed-dose combination of acarbose and metformin with the corresponding loose combination as well as the drug-drug interaction potential between both drugs in healthy adult male subjects

WHAT IS KNOWN AND OBJECTIVE

Both metformin and acarbose are recommended monotherapy and add-on therapy in type 2 diabetes mellitus (T2DM). A fixed-dose combination (FDC) of acarbose and metformin has been developed to reduce pill burden and potentially improve compliance. The current study investigated the bioequivalence of the acarbose/metformin FDC compared with the individual agents administered simultaneously (loose combination). Secondary endpoints were the safety and tolerability of the FDC and the potential for drug-drug interactions between acarbose and metformin.

METHODS

A single-centre, randomized, open-label, four-period crossover study was conducted in healthy male Korean subjects aged 18-45 years. Following one-period balanced Williams design, participants were randomized to receive four single oral treatments on different study days separated by ≥7 days' washout. Treatments were as follows: (i) acarbose/metformin 50/500 mg FDC (test); (ii) acarbose 50 mg and metformin 500 mg as loose combination (reference); (iii) acarbose 50 mg; and (iv) metformin 500 mg. Serial blood samples were taken for glucose and insulin levels for 4 h after a sucrose load on the day before and day of study drug administration. Additionally, serial blood samples were taken for analysis of metformin levels for 24 h after each drug containing metformin. The area under the curve for 4 h post-test (AUC0-4 h ) and the maximal serum concentration (Cmax ) of plasma glucose and serum insulin were primary pharmacodynamic (PD) parameters, and Cmax , AUC0-last and AUC for metformin levels were primary pharmacokinetic (PK) parameters. The bioequivalence of the FDC to the loose combination was considered established if the 90% confidence intervals (CIs) of the baseline-adjusted PD parameter ratios (test vs. reference) for plasma glucose and the PK parameter ratios for metformin fell completely within current acceptance limits (0·8-1·25).

RESULTS AND DISCUSSION

Thirty-three of 40 randomized subjects completed the study; five withdrew consent and two discontinued because of adverse events (AEs). The 24-h plasma concentration-time curves of metformin and the 4-h plasma glucose-time curves after acarbose/metformin FDC (test) and acarbose + metformin loose combination (reference) were almost superimposable. The geometric least squares (LS) mean of the RatioAUC and RatioCmax for plasma glucose after the FDC vs. loose combination, and the LS mean of the ratios in metformin AUC, AUC0-last and Cmax were close to unity, and the 90% CI of all these parameters fell within the predefined equivalence range of 0·8-1·25, confirming bioequivalence. The metformin AUC was reduced by 26% and Cmax by 34% after acarbose + metformin compared with metformin alone. Eight subjects (20·0%) reported AEs, but all were mild, and most were gastrointestinal, as expected for these agents. The incidence of AEs was not higher with the combinations vs. monotherapy.

WHAT IS NEW AND CONCLUSION

These data demonstrate that the acarbose/metformin FDC is bioequivalent to the loose combination of these agents. Although acarbose slightly reduced the bioavailability of metformin, the accumulated evidence of the efficacy of this combination implies that this is clinically irrelevant. The observed AE profile was consistent with the established knowledge on the safety of the two drugs.

Sodium terephthalate as an organic anode material for sodium ion batteries

Disodium terephthalate and its various derivatives are synthesized via simple acid-base chemistry for anode materials in Na ion batteries. They show excellent electrochemical performance, including little capacity fading over 90 cycles, ideal redox potential, and excellent rate performance, making them promising candidates for Na ion batteries.

Enhanced Ih depresses rat entopeduncular nucleus neuronal activity from high-frequency stimulation or raised Ke+

High-frequency stimulation (HFS) is used to treat a variety of neurological diseases, yet its underlying therapeutic action is not fully elucidated. Previously, we reported that HFS-induced elevation in [K(+)](e) or bath perfusion of raised K(e)(+) depressed rat entopeduncular nucleus (EP) neuronal activity via an enhancement of an ionic conductance leading to marked depolarization. Herein, we show that the hyperpolarization-activated (I(h)) channel mediates the HFS- or K(+)-induced depression of EP neuronal activity. The perfusion of an I(h) channel inhibitor, 50 microM ZD7288 or 2 mM CsCl, increased input resistance by 23.5 +/- 7% (ZD7288) or 35 +/- 10% (CsCl), hyperpolarized cells by 3.4 +/- 1.7 mV (ZD7288) or 2.3 +/- 0.9 mV (CsCl), and decreased spontaneous action potential (AP) frequency by 51.5 +/- 12.5% (ZD7288) or 80 +/- 13.5% (CsCl). The I(h) sag was absent with either treatment, suggesting a block of I(h) channel activity. Inhibition of the I(h) channel prior to HFS or 6 mM K(+) perfusion not only prevented the previously observed decrease in AP frequency, but increased neuronal activity. Under voltage-clamp conditions, I(h) currents were enhanced in the presence of 6 mM K(+). Calcium is also involved in the depression of EP neuronal activity, since its removal during raised K(e)(+) application prevented this attenuation and blocked the I(h) sag. We conclude that the enhancement of I(h) channel activity initiates the HFS- and K(+)-induced depression of EP neuronal activity. This mechanism could underlie the inhibitory effects of HFS used in deep brain stimulation in output basal ganglia nuclei.

Transition to seizures in the isolated immature mouse hippocampus: a switch from dominant phasic inhibition to dominant phasic excitation

The neural dynamics and mechanisms responsible for the transition from the interictal to the ictal state (seizures) are unresolved questions in epilepsy. It has been suggested that a shift from inhibitory to excitatory GABAergic drive can promote seizure generation. In this study, we utilized an experimental model of temporal lobe epilepsy which produces recurrent seizure-like events in the isolated immature mouse hippocampus (P8-16), perfused with low magnesium ACSF, to investigate the cellular dynamics of seizure transition. Whole-cell and perforated patch recordings from CA1 pyramidal cells and from fast- and non-fast-spiking interneurons in the CA1 stratum oriens hippocampal region showed a change in intracellular signal integration during the transition period, starting with dominant phasic inhibitory synaptic input, followed by dominant phasic excitation prior to a seizure. Efflux of bicarbonate ions through the GABA A receptor did not fully account for this excitation and GABAergic excitation via reversed IPSPs was also excluded as the prime mechanism generating the dominant excitation, since somatic and dendritic GABA A responses to externally applied muscimol remained hyperpolarizing throughout the transition period. In addition, abolishing EPSPs in a single neuron by intracellularly injected QX222, revealed that inhibitory synaptic drive was maintained throughout the entire transition period. We suggest that rather than a major shift from inhibitory to excitatory GABAergic drive prior to seizure onset, there is a change in the interaction between afferent synaptic inhibition, and afferent and intrinsic excitatory processes in pyramidal neurons and interneurons, with maintained inhibition and increasing, entrained 'overpowering' excitation during the transition to seizure.

High frequency stimulation or elevated K+ depresses neuronal activity in the rat entopeduncular nucleus

High frequency stimulation (HFS) is applied to many brain regions to treat a variety of neurological disorders/diseases, yet the mechanism(s) underlying its effects remains unclear. While some studies showed that HFS inhibits the stimulated nucleus, others report excitation. In this in vitro study, we stimulated the rat globus pallidus interna (entopeduncular nucleus, EP), a commonly stimulated area for Parkinson's disease, to investigate the effect of HFS-induced elevation of extracellular potassium (K(+)(e)) on rat EP neuronal activity. Whole-cell patch-clamp recordings and [K(+)](e) measurements were obtained in rat EP brain slices before, during and after HFS. After HFS (150 Hz, 10 s), [K(+)](e) increased from 2.5-9.6+/-1.4 mM, the resting membrane potential of EP neurons depolarized by 11.1+/-2.5 mV, spiking activity was significantly depressed, and input resistance decreased by 25+/-6%. The GABA(A) receptor blocker, gabazine, did not prevent these effects. The bath perfusion of 6 or 10 mM K(+), with or without synaptic blockers, mimicked the HFS-mediated effects: inhibition of spike activity, a 20+/-9% decrease in input resistance and a 17.4+/-3.0 mV depolarization. This depolarization exceeded predicted values of elevated [K(+)](e) on the resting membrane potential. A depolarization block did not fully account for the K(+)-induced inhibition of EP neuronal activity. Taken together, our results show that HFS-induced elevation of [K(+)](e) decreased EP neuronal activity by the activation of an ion conductance resulting in membrane depolarization, independent of synaptic involvement. These findings could explain the inhibitory effects of HFS on neurons of the stimulated nucleus.

Primary clear cell sarcoma of bone

Clear cell sarcoma is a rare soft tissue sarcoma of young adults with melanocytic differentiation. It occurs predominantly in the soft tissue of extremities, typically involving tendons and aponeuroses. Primary clear cell sarcoma of bone is extremely rare. We report a case of primary clear cell sarcoma of the right first metatarsal in a 48-year-old woman and provide a literature review of the entity.

Surface modification of polyhydroxyalkanoate films and their interaction with human fibroblasts

A poly(3-hydroxybutylate-co-hydroxyvalerate) (PHA) film containing 34 mol.% 3-hydroxyvalerate (Biopol D600P) was prepared by the solvent cast method using a 10 wt.% chloroform solution of PHA. The PHA film was exposed to an oxygen plasma glow discharge to produce peroxides on its surfaces. These peroxides were then used as catalysts for the polymerization of acrylic acid (AA) in order to prepare carboxyl group-introduced PHA (PHA-C). Insulin-immobilized PHA was prepared using the coupling reaction of PU-C with insulin. The surface-modified PHAs were then characterized by attenuated total reflection Fourier transform infrared spectroscopy, electron spectroscopy for chemical analysis, and a contact angle goniometer. The amounts of insulin directly coupled to the carboxyl groups on PHA-C and coupled to the terminus amino groups of the grafted polyethylene oxide were 2.9 and 0.8 microg cm(-2), respectively. The PHA water contact angle (75 degrees ) decreased with AA grafting (33 degrees ) and insulin immobilization (31 degrees ), thereby exhibiting the increased hydrophilicity of the modified PHAs. When compared with PHA and PHA-C, the proliferation of human fibroblasts in the presence of serum was significantly accelerated on the insulin-immobilized PHAs.

Fibrosarcoma in bizarre parosteal osteochondromatous proliferation

Bizarre parosteal osteochondromatous proliferation (BPOP) is a rare benign lesion predominantly involving the small bones of the hands and feet. Malignant transformation in BPOP has not been documented in the English literature. This report presents the coexistence of fibrosarcoma with BPOP in the right distal fibula of an 18-year-old woman.

Grading, image analysis, and stereopsis of digitally compressed fundus images

PURPOSE

To investigate the effects of image digitization and compression on the ability to identify and quantify features in color fundus photographs.

METHODS

Color fundus photographs were digitized as tagged image file format (TIFF) and high-compression (80:1) and low-compression (30:1) joint photographic experts group (JPEG) images. Rerendered images were subjected to standard grading protocols developed for a clinical trial, and digitized images were subjected to image analysis software for drusen identification and quantitation. Re-created stereoscopic images were compared subjectively with originals.

RESULTS

Original, TIFF, and low-compression (30:1) JPEG images were virtually indistinguishable when subjected to close scrutiny with magnification. The overall quality of high-compression (80:1) JPEG images and images digitized at 500 dots per inch was markedly reduced. Protocol grading of original and digitized images was highly concordant within the repeatability of multiple grading of original images. The area subtended by drusen differed by less than 1.0% for all uncompressed and compressed image pairs quantified. Stereoscopic information was accurately preserved when compared with originals for TIFF and low-compression JPEG images.

CONCLUSIONS

Fundus images can be digitized and stored with significant compression while preserving stereopsis and image quality suitable for quantitative image analysis and semiquantitative grading. Low-compression (30:1) JPEG images may be suitable for archiving and telemedical applications.

Computerized stereochronoscopy and alternation flicker to detect optic nerve head contour change

PURPOSE/BACKGROUND

Stereochronoscopy, a technique previously explored but abandoned for glaucoma diagnosis, viewed optic nerve images acquired at separate points in time as if a stereo pair. Prior efforts to exploit this technique were impaired by a lack of superimposability for sequential optic nerve images. We investigated computerized registration techniques for aligning sequential, monoscopic optic disc images to facilitate sensitive detection of optic nerve head contour changes in glaucoma.

DESIGN

Algorithm and software development. Comparisons with standard techniques.

MATERIALS

Existing patient records from the Glaucoma Service, Scheie Eye Institute, University of Pennsylvania.

METHODS

Two sets of optic disc photographs, separated in time by 1 to 18 years, of 25 eyes with and without glaucomatous optic disc progression were digitized. We developed custom software for accurate image alignment. Change in disc morphology was then judged by digital stereochronoscopy and user-controlled alternation flicker of superimposed, time-separated images on a computer monitor. Comparisons were made with standard stereoscopic comparison.

MAIN OUTCOME MEASURE

Identification of change or no change in optic nerve head contour for images acquired at separate points in time.

RESULTS

Image processing and registration permits accurate alignment of optic disc photographs. Alternation flicker of superimposed, sequential images facilitates image comparison and detection of change as indicated by change in vessel position, color, and other cues for contour change. A high concordance was found between standard stereoscopic comparison and alternation flicker. In several cases, reinspection of stereo comparison led to a revised judgment on the basis of disc changes rendered more obvious with alternation flicker. Digital stereochronoscopy was less concordant with standard techniques.

CONCLUSIONS

Digital image processing techniques and alternation flicker provide a simple, sensitive, software-based method for detecting glaucomatous optic disc change.

Structural biology of Rad50 ATPase: ATP-driven conformational control in DNA double-strand break repair and the ABC-ATPase superfamily

To clarify the key role of Rad50 in DNA double-strand break repair (DSBR), we biochemically and structurally characterized ATP-bound and ATP-free Rad50 catalytic domain (Rad50cd) from Pyrococcus furiosus. Rad50cd displays ATPase activity plus ATP-controlled dimerization and DNA binding activities. Rad50cd crystal structures identify probable protein and DNA interfaces and reveal an ABC-ATPase fold, linking Rad50 molecular mechanisms to ABC transporters, including P glycoprotein and cystic fibrosis transmembrane conductance regulator. Binding of ATP gamma-phosphates to conserved signature motifs in two opposing Rad50cd molecules promotes dimerization that likely couples ATP hydrolysis to dimer dissociation and DNA release. These results, validated by mutations, suggest unified molecular mechanisms for ATP-driven cooperativity and allosteric control of ABC-ATPases in DSBR, membrane transport, and chromosome condensation by SMC proteins.

Subcellular phototoxicity of 5-aminolaevulinic acid (ALA)

BACKGROUND AND OBJECTIVE

5-aminolaevulinic acid (ALA) is a new, promising photosensitizer for PDT of cancer. Subcellular toxicity induced by ALA and light exposure in single cells was studied to elucidate the mechanism of cell damage.

STUDY DESIGN/MATERIALS AND METHODS

CPAE, PTK2, and rat neonatal myocardial cells treated with ALA were examined for localization using fluorescence microscopy and for subcellular phototoxicity using 630 nm laser microbeam irradiation of specific subcellular regions.

RESULTS

In CPAE and PTK2 cells, a large amount of fluorescence was detected in the peri-nuclear cytoplasm. In rat neonatal myocardial cells, the sensitizer selectively localized in the large mitochondria. In both cell types, there was little phototoxicity when the peripheral cytoplasmic region was exposed, as compared to considerable phototoxicity with exposure of either the perinuclear or nuclear regions.

CONCLUSION

Both the CPAE and PTK2 cells demonstrated that the nucleus followed by the perinuclear cytoplasm are the most sensitive cell areas with no sensitivity in the peripheral cytoplasm.

Large tumor endoprostheses and extracortical bone-bridging: 28 patients followed 10-20 years

Aseptic loosening is a common cause of failure in large tumor endoprostheses. The concept of extracortical bone-bridging was developed to tackle the problem of loosening. New bone which forms across the junction of the bone-prosthesis junction is believed to improve fixation by controlling the transfer of stresses across the junction as well as by giving additional stability to the prosthesis. We present the long-term experience with this concept following major reconstruction after tumor and non-tumor conditions in 31 patients. The overall function was good for upper and lower limb prostheses. Most patients had extracortical bone bridging which was maintained for over 10 years. In 1/3 of patients this involved over 75% of the prosthetic circumference. Prosthetic survival was best with intercalary devices, followed by proximal femoral and distal femoral prostheses. Survival of prostheses in young active patients was similar to that reported in older patients undergoing primary joint replacement.

Structure of the major peanut allergen Ara h 1 may protect IgE-binding epitopes from degradation

In the past decade, there has been an increase in allergic reactions to peanut proteins, sometimes resulting in fatal anaphylaxis. The development of improved methods for diagnosis and treatment of peanut allergies requires a better understanding of the structure of the allergens. Ara h 1, a major peanut allergen belonging to the vicilin family of seed storage proteins, is recognized by serum IgE from >90% of peanut-allergic patients. In this communication, Ara h 1 was shown to form a highly stable homotrimer. Hydrophobic interactions were determined to be the main molecular force holding monomers together. A molecular model of the Ara h 1 trimer was constructed to view the stabilizing hydrophobic residues in the three dimensional structure. Hydrophobic amino acids that contribute to trimer formation are at the distal ends of the three dimensional structure where monomer-monomer contacts occur. Coincidentally, the majority of the IgE-binding epitopes are also located in this region, suggesting that they may be protected from digestion by the monomer-monomer contacts. On incubation of Ara h 1 with digestive enzymes, various protease-resistant fragments containing IgE-binding sites were identified. The highly stable nature of the Ara h 1 trimer, the presence of digestion resistant fragments, and the strategic location of the IgE-binding epitopes indicate that the quaternary structure of a protein may play a significant role in overall allergenicity.

An intelligent, interactive platform for ophthalmic teaching, telemedicine, and telecollaboration: design considerations and prototype construction

The development of technologies permitting processing, compression, and transmission of digital images and image sequences enables powerful methodologies for local and remote medical teleconsultation. We are developing a slit-lamp-based ophthalmic augmented reality (image overlay) environment incorporating features to permit real-time, interactive teaching, telemedicine, and telecollaboration. A binocular slit-lamp biomicroscope interfaced to a CCD camera, framegrabber board, and PC permits acquisition and rendering of anterior segment and retinal images. Computer-vision algorithms facilitate robust tracking, registration, and near-video-rate image overlay of previously stored retinal photographic and angiographic images onto the real-time fundus image. Our algorithms facilitate shared control of pointing, drawing, and measuring functions registered with the retinal image video stream and direct audio communication between an examiner (student, generalist) and remote observer (instructor, specialist). Bandwidth and video compression considerations limit the frame rate and latency for video stream transmission. Excellent and acceptable performance are demonstrated in model eyes over a local area network and through a modem connection, respectively. These studies represent the first investigations towards the design and implementation of an intelligent platform for ophthalmic telemedicine and telecollaboration.

Computer-vision-enabled augmented reality fundus biomicroscopy

PURPOSE

To guide treatment for macular diseases and to facilitate real-time image measurement and comparison, investigations were initiated to permit overlay of previously stored photographic and angiographic images directly onto the real-time slit-lamp biomicroscopic fundus image.

DESIGN

Experimental study in model eyes, and preliminary observations in human subjects.

METHODS

A modified, binocular video slit lamp interfaced to a personal computer and framegrabber allows for image acquisition and rendering of stored images overlaid onto the real-time slit-lamp biomicroscopic fundus image. Development proceeds with rendering on a computer monitor, while construction is completed on a miniature display interfaced directly with one of the slit-lamp oculars. Registration and tracking are performed with in-house-developed software.

MAIN OUTCOME MEASURES

Tracking speed and accuracy, ergonomic acceptability.

RESULTS

Computer-vision algorithms permit robust montaging, tracking, registration, and rendering of previously stored photographic and angiographic images onto the real-time slit-lamp fundus biomicroscopic image. In model eyes and in preliminary studies in a human eye, optimized registration permits near-video-rate image overlay with updates at 3 to 10 Hz and misregistration errors on the order of 1 to 5 pixels.

CONCLUSIONS

A prototype for ophthalmic augmented reality (image overlay) is presented. The current hardware/software implementation allows for robust performance.

Laser-induced drusen reduction improves visual function at 1 year. Choroidal Neovascularization Prevention Trial Research Group

OBJECTIVE

To describe the relationship of laser-induced drusen reduction to change in visual function at 1 year among patients enrolled in the Choroidal Neovascularization Prevention Trial (CNVPT).

DESIGN

Comparison of groups with and without drusen reduction; follow-up of a randomized controlled trial.

PARTICIPANTS

Evaluations of drusen and visual acuity at baseline and at 1 year were performed for 351 eyes of the 432 eyes enrolled in the CNVPT Bilateral Drusen Study and Fellow Eye Study (81%). One hundred eighty-four eyes were assigned to observation, and 167 eyes were assigned to laser treatment. Eyes with conditions that precluded an analysis of drusen reduction, such as those that developed choroidal neovascularization (CNV) within the first year, are excluded from this analysis.

METHODS

Change in macular drusen between initial visit and after 1 year was assessed by side-by-side grading by evaluators masked to information on visual function. Visual acuity, contrast threshold, and critical print size were measured by certified visual function examiners.

MAIN OUTCOME MEASURES

Change in visual acuity is the primary outcome. Change in contrast threshold and change in critical print size are secondary outcome measures.

RESULTS

Laser-treated eyes with 50% or more drusen reduction at 1 year had more 1- and 2-line increases in visual acuity and less losses in visual acuity compared with laser-treated eyes with less drusen reduction or with observed eyes (P = 0.001). Similar improvements were noted for contrast threshold but not critical print size at 1 year.

CONCLUSIONS

Laser-induced drusen reduction is associated with improved visual acuity and contrast sensitivity in eyes at 1 year. Longer term effects of laser-induced drusen reduction on visual function require additional observation. The overall potential value of laser treatment in eyes with high-risk drusen requires consideration of not only short-term effects on vision but also the effects of CNV and atrophy on vision.

Computer-assisted, interactive fundus image processing for macular drusen quantitation

PURPOSE

To design and validate a software package to quantitate the area subtended by drusen in color fundus photographs for the conduct of efficient, accurate clinical trials in age-related macular degeneration.

DESIGN

Algorithm and software development. Comparisons with manual methodologies.

PARTICIPANTS

Evaluation and testing on color fundus photographs from patient records and from eyes enrolled in the Choroidal Neovascularization Prevention Trial.

METHODS

Fundus photographs of eyes with drusen were digitized. The green channel was selected for maximum contrast and preprocessed with filtering and shade correction to minimize noise, improve contrast, and correct for illumination and background inhomogeneities. Local thresholding and region-growing algorithms identified drusen. Multiple levels of supervision were incorporated to maximize robustness, accuracy, and validity. Validation studies compared computer-assisted with manual grading by an experienced grader. Intraclass correlation coefficients were calculated as a measure of the concordance between manual and computer-assisted fundus gradings.

MAIN OUTCOME MEASURES

Drusen area and concordance with manual grading.

RESULTS

Automated supervised image analysis offers extreme robustness and accuracy. Most images were segmented with little or no supervision, with processing times on the order of 5 seconds. More complicated images required supervision and a total analysis time varying from 20 seconds to 5 minutes, with most of this time devoted to inspection and comparison. Interactive image processing affords arbitrarily close concordance with manual drusen identification, with calculated intraclass correlation coefficients of 0.92 and 0.93 for comparison of manual with automated, supervised grading by two observers.

CONCLUSIONS

Automated supervised fundus image analysis is an efficient, robust, valid technique for drusen quantitation from color fundus photographs. This approach should prove useful in the conduct of efficient accurate clinical trials for age-related macular degeneration.

Reoperation for failed prosthetic replacement used for limb salvage

Patients with segmental bone and joint replacement prostheses because of tumors increasingly need revision surgery because of their long term survival. Between 1970 and 1990, 208 custom prosthetic replacements were performed for limb salvage in patients with tumors. Reoperations were required in 52 patients. The mean time to reoperation was 37 months. The reoperation procedures included 35 prosthetic revisions, 11 amputations, four arthrodeses, one vascularized fibular graft, and one open reduction and internal fixation of a fracture with supplemental bone graft. Functional assessment using the new Musculoskeletal Tumor Society scoring system was available for the 36 living patients, and their mean rating was 63% (18.9) at 12 years' mean followup. Of the 35 patients who received a new prosthesis, 12 (33%) patients needed a third operation at mean followup of 68 months. The probability of prosthetic survival in the group of 35 patients needing revision to the same or another prosthesis was 79% at 5 years and 65% at 10 years. The chance and frequency of needing reoperation increased as patients survived longer. Reoperations for tumor recurrence or infection usually resulted in amputation. Reoperation for failed initial segmental bone and joint prosthetic replacement is feasible and effective and can be done without jeopardizing subsequent patient and implant survival or without significantly affecting functional results compared with the values before reoperation.

Pseudoanaplastic chondromyxoid fibroma

A 19-year-old man presented with a chondromyxoid fibroma of the distal phalanx of the great toe that was originally diagnosed as osteosarcoma rather than "dedifferentiated" chondrosarcoma. Radiographs showed a large, expansive, and calcified tumor of the distal phalanx. Although the tumor had the architectural and matrix patterns of a chondromyxoid fibroma, high-power examination demonstrated that the lesion had such severe nuclear pleomorphism that it was mistaken for high-grade sarcoma. The purpose of this report is to present the criteria used to differentiate a benign pseudoanaplastic chondromyxoid fibroma from chondrogenic high-grade sarcomas.

Biochemical and structural analysis of the IgE binding sites on ara h1, an abundant and highly allergenic peanut protein

Allergy to peanut is a significant IgE-mediated health problem because of the high prevalence, potential severity, and chronicity of the reaction. Ara h1, an abundant peanut protein, is recognized by serum IgE from >90% of peanut-sensitive individuals. It has been shown to belong to the vicilin family of seed storage proteins and to contain 23 linear IgE binding epitopes. In this communication, we have determined the critical amino acids within each of the IgE binding epitopes of Ara h1 that are important for immunoglobulin binding. Surprisingly, substitution of a single amino acid within each of the epitopes led to loss of IgE binding. In addition, hydrophobic residues appeared to be most critical for IgE binding. The position of each of the IgE binding epitopes on a homology-based molecular model of Ara h1 showed that they were clustered into two main regions, despite their more even distribution in the primary sequence. Finally, we have shown that Ara h1 forms a stable trimer by the use of a reproducible fluorescence assay. This information will be important in studies designed to reduce the risk of peanut-induced anaphylaxis by lowering the IgE binding capacity of the allergen.

Functional selection and characterization of DNA binding sites for trp repressor of Escherichia coli

trp repressor of Escherichia coli controls transcription initiation in operons involved in tryptophan biosynthesis by binding to operator sequences within the regulated promoters. Naturally occurring operators are homologous over an 18-base pair region and display dyad symmetry. We have examined the sequence determinants of a repressor binding site using a functional selection/polymerase chain reaction (PCR) amplification strategy. A trp repressor affinity column was generated and used to select binding-competent DNAs from a randomized pool of synthetic double-stranded DNA. DNAs that showed tryptophan-dependent high-affinity binding were eluted by addition of the tryptophan analog beta-indole acrylic acid and amplified by PCR. Following iterative cycles of affinity chromatography and PCR, the selected DNAs were cloned and sequenced. The CTAG tetranucleotide, present in the consensus sequence of all natural operators, was found in all selected DNAs. Mapping experiments utilizing the repressor affinity column showed the CTAG motif to be a critical determinant for repressor binding. Quantitative electrophoretic mobility shift assays with purified trp repressor revealed that although some of the DNAs were bound by one repressor dimer, others were bound by two repressor dimers with cooperativity. Measured binding constants ranged from 0.035 to 0.5 nM for the selected DNAs, compared with 0.1 nM for the trp operator.

Comparative effects of two polychlorinated biphenyl congeners on calcium homeostasis in rat cerebellar granule cells

Some polychlorinated biphenyls (PCBs) have been reported to alter locomotor activity and decrease brain dopamine function in laboratory animals. PCBs with ortho- and/or parachlorine substitutions and varying number of chlorinations are known to decrease cell dopamine content in vitro and have been detected in brains of animals exposed to PCBs, suggesting that the neurotoxicity could be mediated by ortho-substituted congeners. Dopamine or other neurotransmitter uptake and release phenomena are dependent on the maintenance of intracellular Ca2+ homeostasis, and perturbations in Ca2+ homeostasis could lead to altered cell function and/or death. We compared the effects of two PCB congeners on Ca2+ homeostasis in cerebellar granule cells: 2,2'-dichlorobiphenyl (DCBP), a putative neurotoxic congener, and 3,3',4,4',5-pentachlorobiphenyl (PCBP), a presumed nonneurotoxic congener. In cerebellar granule cells (6-8 days in vitro), DCBP was cytotoxic as indicated by a significant increase in LDH leakage at 200 microM after 2 hr of exposure and at 100 microM after 4 hr exposure. PCBP, on the other hand, did not affect LDH leakage even at 200 microM for up to 4 hr. Although both congeners increased cerebellar granule cell [Ca2+]i, DCPB was more effective in increasing [Ca2+]i to a greater extent than PCBP. The increase in [Ca2+]i produced by both congeners was not transient, but a steady rise was observed with time. To understand cellular Ca(2+)-buffering capacity, Ca2+ sequestration and Ca2+ extrusion were studied in mitochondria, microsomes, and synaptosomes, isolated from adult rat cerebellum. DCBP was a potent inhibitor of 45Ca2+ uptake by mitochondria (IC50 = 6.17 +/- 0.53 microM) and microsomes (IC50 = 7.61 +/- 0.35 microM). PCBP inhibited Ca2+ sequestration by mitochondria (68% of control) and microsomes (72% of control), but the effects were much less than those produced by equivalent concentrations of DCBP. Synaptosomal Ca(2+)-ATPase was inhibited by DCBP, but not by PCBP. These results indicate that at concentrations where cytotoxicity in cerebellar granule cells was not observed, DCBP increased intracellular [Ca2+]i, and at the same concentrations, Ca2+ sequestration by intracellular organelles and Ca(2+)-ATPase in synaptic plasma membrane were inhibited. Although PCBP increased [Ca2+]i in cerebellar granule cells to some extent, it was not potent in affecting Ca2+ sequestration or Ca2+ extrusion in adult cerebellar components. Hence, PCBP-induced slight increase of [Ca2+]i levels in the cells might have been associated with effective Ca2+ sequestration by intracellular organelles, as seen in cerebellar preparations. The results of this study support the hypothesis that the position of chlorine substitution on the biphenyl ring and/or number of chlorine substitutions may have significant implications for predicting potential effects of PCB congeners in the nervous system, and perturbations in Ca2+ homeostasis might play a significant role in the neuroactivity of PCBs.