bluuebunny/crossref_metadata_2025 huggingface dataset:
Genetic Identification of Spotted Owls, Barred Owls, and Their Hybrids: Legal Implications of Hybrid Identity
Authors: HAIG SUSAN M. , MULLINS THOMAS D. , FORSMAN ERIC D. , TRAIL PEPPER W. , WENNERBERG LIV
Published: September 2004

Abstract: Recent population expansion of Barred Owls ( Strix varia) into western North America has led to concern that they may compete with and further harm the Northern Spotted Owl ( S. occidentalis caurina), which is already listed as threatened under the U.S. Endangered Species Act (ESA). Because they hybridize, there is a legal need under the ESA for forensic identification of both species and their hybrids. We used mitochondrial control‐region DNA and amplified fragment‐length polymorphism (AFLP) analyses to assess maternal and biparental gene flow in this hybridization process. Mitochondrial DNA sequences (524 base pairs) indicated large divergence between Barred and Spotted Owls (13.9%). Further, the species formed two distinct clades with no signs of previous introgression. Fourteen diagnostic AFLP bands also indicated extensive divergence between the species, including markers differentiating them. Principal coordinate analyses and assignment tests clearly supported this differentiation. We found that hybrids had unique genetic combinations, including AFLP markers from both parental species, and identified known hybrids as well as potential hybrids with unclear taxonomic status. Our analyses corroborated the findings of extensive field studies that most hybrids genetically sampled resulted from crosses between female Barred Owls and male Spotted Owls. These genetic markers make it possible to clearly identify these species as well as hybrids and can now be used for research, conservation, and law enforcement. Several legal avenues may facilitate future conservation of Spotted Owls and other ESA‐listed species that hybridize, including the ESA similarity‐of‐appearance clause (section 4[e]) and the Migratory Bird Treaty Act. The Migratory Bird Treaty Act appears to be the most useful route at this time.
Linking Wild and Captive Populations to Maximize Species Persistence: Optimal Translocation Strategies
Authors: TENHUMBERG BRIGITTE , TYRE ANDREW J. , SHEA KATRIONA , POSSINGHAM HUGH P.
Published: September 2004

Abstract:  Captive breeding of animals is widely used to manage endangered species, frequently with the ambition of future reintroduction into the wild. Because this conservation measure is very expensive, we need to optimize decisions, such as when to capture wild animals or release captive‐bred individuals into the wild. It is unlikely that one particular strategy will always work best; instead, we expect the best decision to depend on the number of individuals in the wild and in captivity. We constructed a first‐order Markov‐chain population model for two populations, one captive and one wild, and we used stochastic dynamic programming to identify optimal state‐dependent strategies. The model recommends unique sequences of optimal management actions over several years. A robust rule of thumb for species that can increase faster in captivity than in the wild is to capture the entire wild population whenever the wild population is below a threshold size of 20 females. This rule applies even if the wild population is growing and under a broad range of different parameter values. Once a captive population is established, it should be maintained as a safety net and animals should be released only if the captive population is close to its carrying capacity. We illustrate the utility of this model by applying it to the Arabian oryx (Oryx leucoryx). The threshold for capturing the entire Arabian oryx population in the wild is 36 females, and captive‐bred individuals should not be released before the captive facilities are at least 85% full.
Appreciating Ecological Complexity: Habitat Contours as a Conceptual Landscape Model
Authors: FISCHER JOERN , LINDENMAYER DAVID B. , FAZEY IOAN
Published: September 2004

Abstract:  Organisms respond to their surroundings at multiple spatial scales, and different organisms respond differently to the same environment. Existing landscape models, such as the “fragmentation model” (or patch‐matrix‐corridor model) and the “variegation model,” can be limited in their ability to explain complex patterns for different species and across multiple scales. An alternative approach is to conceptualize landscapes as overlaid species‐specific habitat contour maps. Key characteristics of this approach are that different species may respond differently to the same environmental conditions and at different spatial scales. Although similar approaches are being used in ecological modeling, there is much room for habitat contours as a useful conceptual tool. By providing an alternative view of landscapes, a contour model may stimulate more field investigations stratified on the basis of ecological variables other than human‐defined patches and patch boundaries. A conceptual model of habitat contours may also help to communicate ecological complexity to land managers. Finally, by incorporating additional ecological complexity, a conceptual model based on habitat contours may help to bridge the perceived gap between pattern and process in landscape ecology. Habitat contours do not preclude the use of existing landscape models and should be seen as a complementary approach most suited to heterogeneous human‐modified landscapes.
Intercrosses and the U.S. Endangered Species Act: Should Hybridized Populations be Included as Westslope Cutthroat Trout?
Authors: ALLENDORF FRED W. , LEARY ROBB F. , HITT NATHANIEL P. , KNUDSEN KATHY L. , LUNDQUIST LAURA L. , SPRUELL PAUL
Published: September 2004

Abstract: There are currently no policy guidelines for treating hybrids under the U.S. Endangered Species Act (ESA). We considered the scientific basis for determining whether hybridized populations should be included as part of the westslope cutthroat trout (Oncorhynchus clarki lewisi) unit considered for listing under the ESA. Westslope cutthroat trout are threatened by genomic extinction because of widespread introgressive hybridization with introduced rainbow trout (O. mykiss) and Yellowstone cutthroat trout (O. c. bouvieri). Experimental results suggest that first‐generation hybrids between westslope cutthroat trout and rainbow trout have reduced fitness. However, hybridization may spread even when hybrids have severely reduced fitness because the production of hybrids is unidirectional—that is, all the progeny of a hybrid will be hybrids. In addition, heterosis resulting from the sheltering of deleterious recessive alleles in early‐generation hybrids may increase the effective rate of introgression. However, such short‐term increases in fitness may disrupt important long‐term adaptations of native populations. The loss of these adaptations will be difficult to detect because some local adaptations might only be apparent during periodic episodes of extreme environmental conditions, such as winter storms, drought, or fire. Thus, rapid spread of hybridization could result in the loss of local adaptations in native populations of westslope cutthroat trout and decrease their probability of long‐term persistence. Protection of populations with some admixture would protect sources of spreading hybridization. Treatment of hybrids in conservation planning depends primarily on the amount of evolutionary divergence between the hybridizing taxa and the geographical extent of introgression. We recommend that only nonhybridized populations be included as westslope cutthroat trout in the unit to be considered for listing. Populations of unknown status should be protected until more information about these populations becomes available.
Managing Individuals' Contributions to Maximize the Allelic Diversity Maintained in Small, Conserved Populations
Authors: FERNÁNDEZ J. , TORO M. A. , CABALLERO A.
Published: September 2004

Abstract:  The maintenance of diversity is, from a genetic perspective, one of the key aims in a conservation program. Because the most widely used measure of genetic diversity is the expected heterozygosity of the population, or gene diversity (GD), most research has been devoted to finding optimal strategies for maximizing this parameter. Little attention has been paid, however, to the development of strategies to manage allelic diversity (AD), the number of alleles maintained in the population. Using computer simulations, we show that the strategies that maximize GD, by managing contributions from parents, keep levels of AD as high as strategies maximizing AD itself, for a wide range of situations including different numbers of molecular markers used and the possibility of evaluating a number of offspring per parent to make decisions. Because maximization of GD also minimizes levels of inbreeding, this should be the strategy of choice in any conservationprogram.
Using Gall Wasps on Oaks to Test Broad Ecological Concepts
Authors: PRICE PETER W. , ABRAHAMSON WARREN G. , HUNTER MARK D. , MELIKA GEORGE
Published: September 2004

Abstract:  Planning conservation of insect herbivores requires knowing what needs to be conserved and developing a set of predictor variables that aid management. We conducted a state‐wide survey to examine the species richness of gall wasps (Hymenoptera: Cynipidae) on six oak species dominant in the threatened scrub‐oak vegetation in peninsular Florida. Eighty‐eight cynipid species were recorded; 23 were new species to Florida (a 35% increase), including 17 species new to science and 6 species newly recorded in the state. The cynipid species represented 68% of cynipids of Florida, on only 24% of oak species sampled. This fauna represents a hotspot of richness, justifying conservation initiatives in scrub‐oak habitat and throughout the state. We derived predictor variables from general ecological concepts: (1) the theory of island biogeography that insect species richness increases as host plant geographic area increases and as local abundance increases, (2) the plant‐architecture hypothesis that insect species richness increases with increased plant size, and (3) phytochemical patterns in leaves, including nutrients and digestibility reducers predicting suitability for insect herbivores. Concepts 1 and 2, developed for large scales and species numbers, were tested at smaller scales relevant to much conservation research and management. A stepwise multiple regression including all predictor variables accounted for 99% of the variance in cynipid species richness with three variables: foliar hemicellulose concentration (81%), host geographic area (16%), and tree height (2%). The trends were negative, however, and opposite to those predicted by concepts 1 and 2. Ecological theory was not applicable to discovery of predictors of cynipid species richness on six oak species. Thus, we promote caution in applying ecological theory to a narrow set of species without specific testing of how patterns conform to theoretical predictions.
Using the KM visual acuity chart for more reliable evaluation of amblyopia compared to the HVOT method
Authors: Moutakis Konstantin , Stigmar Göran , Hall‐Lindberg Janet
Published: September 2004

Purpose:  To evaluate a new letter matching visual acuity (VA) chart (the KM chart) for children aged 5–7 years, designed as a Monoyer‐based chart, in order to obtain a better consistency between school and preschool VA recordings.

Methods:  Visual acuities were assessed using three methods: the HVOT, KM and Monoyer charts. Comparisons were made between the KM method versus the HVOT and Monoyer methods, respectively. Children with normal vision and with different degrees of amblyopia were investigated.

Results:  Visual acuity levels appeared significantly higher in children with amblyopia when tested with the HVOT chart than when tested with the KM chart. Visual acuities obtained with the Monoyer and KM methods were comparable. The difference between the Monoyer and KM methods on the one hand, and the HVOT method on the other, can be explained by the fact that the HVOT chart elicits less crowding effect than the other two charts.

Conclusions:  Visual acuity in children with amblyopia might be overestimated if the HVOT test alone is used to assess vision. Use of the HVOT chart, therefore, should be restricted to the 3.5−4.5 years age group, for whom the KM chart is somewhat too difficult. In our opinion the KM chart should be preferred for use with older preschool children because it shows good consistency with the Monoyer chart.
The occurrence and causes of registered blindness in diabetes patients in Århus County, Denmark
Authors: Jeppesen Peter , Bek Toke
Published: September 2004

Purpose:  To report the occurrence of registered blindness among diabetes patients in Århus County, Denmark during 1993−2002.

Methods:  Data were obtained from a database of 7527 diabetes patients, which included all patients in the county who had been treated for or had experienced visual loss due to diabetic retinopathy since 1992. Of these, 1949 had type 1 diabetes and represented 90% of the type 1 diabetes patient population in the county, and 5459 had type 2 diabetes and represented 40% of the type 2 diabetes patient population in the county.

Results:  The point prevalence of legal blindness was 0.6% for type 1 and 1.5% for type 2 diabetes patients at January 1st, 2003. In type 1 diabetes patients, the major cause of blindness was proliferative diabetic retinopathy (PDR) (66.2% of all blind eyes); in type 2 diabetes patients the major causes were age‐related macular degeneration (21.9%), PDR (18.0%) and diabetic maculopathy (DMac) (18.5%). During 1993−2002 there was a significant decrease in the number of blind eyes secondary to PDR (p = 0.008) in type 1 diabetes patients, and a significant increase in the number of blind eyes secondary to DMac (p = 0.005) in type 2 diabetes patients.

Conclusion:  The major challenge in reducing diabetes‐related blindness is related to the detection and treatment of an increased incidence of diabetic maculopathy in type 2 diabetes patients.
External ophthalmomyiasis caused by Dermatobia hominis. A retrospective study of nine cases and a review of the literature
Authors: Denion Eric , Dalens Pierre‐Henri , Couppié Pierre , Aznar Christine , Sainte‐Marie Dominique , Carme Bernard , Petitbon Jean , Pradinaud Roger , Gérard Max
Published: September 2004

Purpose:  To report nine cases of external ophthalmomyiasis caused by Dermatobia hominis.

Methods:  Retrospective, non‐comparative, interventional case series. Participants consisted of patients (n = 9) presenting at Cayenne Hospital between 1968 and 2003. The location and number of larvae, the larval stage, and the medical and surgical procedures applied were studied in each case.

Results:  Seven patients had palpebral myiasis (including one with three larvae) and two had conjunctival myiasis. Every patient had palpebral oedema. The larval respiratory pore was located on the palpebral skin or free margin or on the conjunctiva. Movements were present within the lesion in at least three patients. Petroleum ointment or ivermectine solution was used in at least four patients to smother or kill the larvae. Extraction under local anaesthesia was possible in six patients, while three required general anaesthesia.

Conclusion:  Several larvae may be present in a patient. Topical ivermectine may help to kill the larvae before extraction is attempted.
An objective method to define outlier optical coherence tomograms and repeatability of retinal nerve fibre layer measurements
Authors: Bergamin Oliver , Anderson Susan C. , Kardon Randy H.
Published: September 2004

Purpose:  To compare the variation in thickness and reflectivity of the retinal nerve fibre layer (RNFL), circumferentially and on repeated testing.

Methods:  In 24 normal eyes and 38 eyes with different optic neuropathies or retinopathies, third‐party optical coherence tomography (OCT) software defined the RNFL border based on the reflectivity pattern across the retina and also provided measurements of the mean reflectivity and total retinal thickness in addition to RNFL thickness. A new Gaussian filtering method was implemented so that the weight of the applied filter was varied for each of five individually repeated scans until an optimum weight filter was determined.

Results:  The scans requiring the highest weight filter could be identified as ‘outlier’ scans that contained measurement or alignment artifacts. There was no difference in the weights of filtering needed for normal and abnormal eyes. The RNFL thickness and reflectivity, and retinal thickness were highly correlated with one another in normal and abnormal eyes.

Conclusions:  A new Gaussian filtering routine was devised that not only defined the most reproducible substructure of the RNFL for a given patient's eye, but also provided a new method of quantifying measurement variability and identification of scans with measurement or alignment artifacts.
Unilateral diabetic macular oedema secondary to central retinal vein congestion
Authors: Christoffersen Nynne , Larsen Michael
Published: September 2004

Purpose:  To describe two cases of strictly unilateral diabetic retinopathy with macular edema where the precipitating factor appears to have been retinal venous congestion.

Methods:  Retrospective interventional case study.

Results:  Examination of fundus photographic records demonstrated generalized venous dilation in the affected eyes years in advance of the development of unilateral diabetic macular edema. Relentless progression of edema and visual loss followed despite retinal photocoagulation treatment and ultimately the affected eyes in both patients developed central retinal vein occlusion. The fellow eyes in both patients remained without retinopathy throughout the period of observation.

Conclusion:  The sequential and strictly unilateral appearance of retinal venous dilation, diabetic macular edema, and central retinal vein occlusion in diabetic patients without fellow‐eye retinopathy suggests that venous congestion induced the progression from hyperglycemic insult to vascular injury in the affected eyes. Presumably, diabetes may cause retinal vascular dysfunction that results in little or no vascular damage unless venous congestion is present. This supports that venous congestion and increased sensitivity to congestion are important components of the pathogenesis of diabetic macular edema.
Enhanced S‐cone syndrome in a Japanese family with a nonsense NR2E3 mutation (Q350X)
Authors: Nakamura Yosuke , Hayashi Takaaki , Kozaki Kenichi , Kubo Akiko , Omoto Satoshi , Watanabe Akira , Toda Kazushige , Takeuchi Tomokazu , Gekka Tamaki , Kitahara Kenji
Published: September 2004

Purpose:  To describe the clinical characteristics of a Japanese male patient with enhanced S‐cone syndrome (ESCS) and investigate the existence of mutations in the NR2E3 gene, which encodes a photoreceptor cell‐specific nuclear receptor.

Methods:  Fundus examinations, fluorescein angiography, colour vision tests, spectral sensitivity, and full‐field and spectral electroretinography were performed. Mutation screening of the NR2E3 gene was performed with polymerase chain reaction (PCR) amplification and direct sequencing.

Results:  We identified a novel homozygous mutation (c.1048C > T), that converts glutamine (CAA) to a termination codon (TAA) at amino acid position 350. The subject's unaffected parents were heterozygous for the mutation, consistent with autosomal recessive transmission. The electroretinographic findings revealed that the patient had neither rod nor 30‐Hz flicker responses but did have cone responses with large a‐wave and low b‐wave amplitudes, similar to the rod‐plus‐cone responses, and also substantial short wavelength‐sensitive (S) cone and extremely diminished long/middle wavelength‐sensitive (L/M) cone responses. In the right eye, spectral sensitivity in the fovea revealed both functional S‐cone and remarkably reduced L‐ and M‐cone sensitivities, which was compatible with the decreased visual acuity (VA) and red/green colour vision defects noted in this eye. In contrast, the patient had good VA and normal red/green colour vision in the left eye.

Conclusion:  The nonsense mutation results in a truncated NR2E3 protein lacking 61 amino acids within the ligand‐binding domain (LBD) that consists of 190 amino acids of the C‐terminus end. Therefore, null function of the LBD is likely to cause ESCS in the patient. The clinical findings for this patient suggest that his left eye, with its functional L/M‐ and S‐cones, was at an earlier stage of the syndrome than his right eye.
Have choroidal and ciliary body melanomas changed during the period 1955–2000?
Authors: Isager Peter , Ehlers Niels , Overgaard Jens
Published: September 2004

Purpose:  To establish whether the presentation of choroidal and ciliary body melanomas and patient survival have changed during the period 1955–2000.

Method:  The study included 209 unselected patients (97 men, 112 women) from Århus County during the period 1955–2000. The median age at treatment was 64 years (range 26–88 years). The disease course from first symptom through clinical and histopathological findings to death was described in a historical follow‐up design. Time trends were evaluated.

Results:  Treatment modality changed over time from enucleation to an almost equal distribution between enucleation and radiation brachytherapy. The age at treatment, or, alternatively, at diagnosis, increased significantly (p = 0.04). No significant time trend was seen for largest basal tumour diameter (p = 0.08) or tumour height (p = 0.27). The clinical and histopathological findings did not show any consistent time trends. No significant time trend was found for melanoma‐specific survival (p = 0.96) or overall survival (p = 0.33).

Conclusion:  No consistent time trends were seen in clinical and histopathological tumour presentation and survival in patients with choroidal or ciliary body melanomas. The increase in age at treatment was in line with an increase in life expectancy in Denmark.
Excessive maternal caffeine exposure during pregnancy is cataractogenic for neonatal crystalline lenses in rats: a biomicroscopic and histopathologic study
Authors: Evereklioglu Cem , Güldür Emin , Alasehirli Belgin , Cengiz Beyhan , Sari Ibrahim , Pirbudak Lütfiye
Published: September 2004

Purpose:  To investigate histologically the influence of maternal caffeine exposure during pregnancy in vivo on crystalline lenses in neonatal rats.

Methods:  Experimentally naive, female Wistar‐albino rats (200–220 g) were mated with adult male rats over 2 days for copulation. After confirming pregnancy with a vaginal smear method, 50 gravid rats (dams) were randomly divided into five groups (n = 10 in each), consisting of one control and four experimental groups. Groups 1, 2 and 3 experimental dams were treated with intraperitoneal (i.p.) caffeine at doses of 25, 50 and 100 mg/kg/day, respectively, during pregnancy from gestational day 9 through to day 21. Group 4 dams were treated with caffeine in distilled water in a gavage at a dose of 50 mg/kg/day. Group 5 control dams were given i.p. saline solution daily for the same period. After normal delivery, the eyes were examined by slit‐lamp biomicroscopy. The neonates were then killed by decapitation at postnatal days 1 or 30 and the eyes removed for histopathologic investigation of the lenses.

Results:  Group 1 and control eyes had normal anterior lens capsules with a single layer of anterior cuboidal epithelial cells, regularly oriented cortical and nuclear lens fibres, and a clear posterior lens capsule with no lining epithelial cells behind the equator. In the remaining groups, histopathologic findings suggesting cataractogenesis included eosinophilic degeneration, lens fibre cell swelling and liquefaction, central lens fibres with retained nuclei, and prominent epithelial cells lining the posterior lens capsule behind the equator. Moreover, some lenses in group 3 had immature cataract on slit‐lamp biomicroscopic examination at postnatal day 30.

Conclusion:  Excessive maternal caffeine exposure during pregnancy had cataractogenic effects on developing crystalline lenses in newborn rat eyes, both macroscopically and histopathologically. If an appropriate dose of caffeine can be identified, caffeine‐induced cataract formation may be used as a new experimental cataract model in animal studies.
Pneumocephalus and presumed meningitis following inconspicuous penetrating periocular trauma
Authors: Detorakis Efstathios T. , Drositis Ioannis , Drakonaki Eleni E. , Panayotaki Evangelia , Deville Jaime G.
Published: September 2004

Purpose:  To report a case of serious intracranial complications in an adolescent youth following a seemingly trivial periocular injury.

Methods:  An adolescent youth was examined and discharged after a small penetrating injury to his left medial canthus. He later presented with blurred vision, nausea and mild pyrexia and underwent a computed tomography (CT) scan of the head and orbits as well as a lumbar puncture.

Results:  The CT scan revealed a fracture in the cribriform plate of the ethmoid bone and the medial orbital wall, as well as pneumocephalus. The lumbar puncture revealed 3000 white cells/mm3 in the cerebrospinal fluid (CSF). After treatment with meningitic doses of intravenous antibiotics, a significant improvement was noted.

Conclusions:  A CT scan, instead of an ordinary head radiograph, may be considered as a first‐choice mode of diagnosis in evaluating even inconspicuous penetrating periocular wounds. Early administration of meningitic doses of antibiotics may significantly improve prognosis.
Prediction of Relative Motion and Probability of Contact Between FPSO and Shuttle Tanker in Tandem Offloading Operation
Authors: Chen Haibo , Moan Torgeir , Haver Sverre , Larsen Kjell
Published: September 2004

Excessive relative motions between Floating Production Storage Offloading Unit (FPSO), and tanker, which are termed as excessive surging and yawing events, are identified as the “failure prone situation” in tandem offloading. These events have contributed to the initiation of tanker drive-off in most collision incidents that happened in the North Sea in recent years. To estimate and reduce the probability of excessive surging and yawing events in tandem offloading, a simulation-based approach, which is based on a state-of-the-art time-domain simulation code SIMO, is presented in this paper. A typical North Sea FPSO and a DP shuttle tanker simulation models are setup in SIMO and calibrated by full-scale measurements. The simulated relative distance and relative heading between FPSO and tanker are analyzed by fitting their extreme values into statistical models which give out probabilities of excessive surging and yawing events. Sensitivity studies are performed to pinpoint contributions from various technical and operational factors. Measures to minimize the occurrence of excessive surging and yawing events are identified in design and operational perspectives.
Biodynamic Response of Human Fingers in a Power Grip Subjected to a Random Vibration
Authors: Dong R. G. , Welcome D. E. , McDowell T. W. , Wu J. Z.
Published: September 2004

Background. Knowledge of the biodynamic response (BR) of the human hand-arm system is an important part of the foundation for the measurement and assessment of hand-transmitted vibration exposure. This study investigated the BR of human fingers in a power grip subjected to a random vibration. Method. Ten male subjects were used in the experiment. Each subject applied three coupling actions to a simulated tool handle at three different finger grip force levels. Results and Conclusions. The BR is practically independent of the hand coupling actions for frequencies at or above 100 Hz. Above 50 Hz, the BR is correlated to finger and hand sizes. Increasing the finger coupling force significantly increases the BR. Therefore, hand forces should be measured and used when assessing hand-transmitted vibration exposure. The results also show that under a constant-velocity vibration, the finger vibration power absorption at frequencies above 200 Hz is approximately twice that at frequencies below 100 Hz. This suggests that the frequency weighting specified in the current ISO 5349-1 (2001) may underestimate the high frequency effect on vibration-induced finger disorders.
Design of an MRI-Compatible Robotic Stereotactic Device for Minimally Invasive Interventions in the Breast†
Authors: Larson Blake T. , Erdman Arthur G. , Tsekos Nikolaos V. , Yacoub Essa , Tsekos Panagiotis V. , Koutlas Ioannis G.
Published: September 2004

The objective of this work was to develop a robotic device to perform biopsy and therapeutic interventions in the breast with real-time magnetic resonance imaging (MRI) guidance. The device was designed to allow for (i) stabilization of the breast by compression, (ii) definition of the interventional probe trajectory by setting the height and pitch of a probe insertion apparatus, and (iii) positioning of an interventional probe by setting the depth of insertion. The apparatus is fitted with five computer-controlled degrees of freedom for delivering an interventional procedure. The entire device is constructed of MR compatible materials, i.e. nonmagnetic and non-conductive, to eliminate artifacts and distortion of the MR images. The apparatus is remotely controlled by means of ultrasonic motors and a graphical user interface, providing real-time MR-guided planning and monitoring of the operation. Joint motion measurements found probe placement in less than 50 s and sub-millimeter repeatability of the probe tip for same-direction point-to-point movements. However, backlash in the rotation joint may incur probe tip positional errors of up to 5 mm at a distance of 40 mm from the rotation axis, which may occur for women with large breasts. The imprecision caused by this backlash becomes negligible as the probe tip nears the rotation axis. Real-time MR-guidance will allow the physician to correct this error. Compatibility of the device within the MR environment was successfully tested on a 4 Tesla MR human scanner.
Static Indentation of Anisotropic Biomaterials Using Axially Asymmetric Indenters—a Computational Study
Authors: Bischoff Jeffrey E.
Published: September 2004

Indentation has historically been used by biomechanicians to extract the small strain elastic or viscoelastic properties of biological tissues. Because of the axisymmetry of indenters used in these studies however, analysis of the results requires the assumption of material isotropy and often yields an “effective” elastic modulus. Since most biological tissues such as bone and myocardium are known to be anisotropic, the use of conventional indentation techniques for estimating material properties is therefore limited. The feasibility of using an axially asymmetric indenter to determine material directions and in-plane material properties for anisotropic tissue is explored here using finite element analysis. The load versus displacement curves as would be measured by an indenter depend on the orientation of the indenter cross section relative to the in-plane material axes, thus suggesting a method for determining the underlying material directions. Additionally, the stiffness of the tissue response to indentation is sensitive to the values of the in-plane anisotropic material properties and prestretches, and thus test results can be used to back out relevant constitutive parameters.
Ultrastructure of the hostpathogen interface in Arabidopsis thaliana leaves infected by the downy mildew Hyaloperonospora parasitica
Authors: Mims C W , Richardson E A , Holt III B F , Dangl J L
Published: September 2004

Transmission electron microscopy was used to examine the hostpathogen interface in Arabidopsis thaliana (L.) Heynh. leaves infected by the biotrophic downy mildew pathogen Hyaloperonospora parasitica (Pers.:Fr.) Constant. Both conventionally fixed as well as high-pressure frozen samples were examined. Excellent preservation of the hostpathogen interface was obtained in many of our high-pressure frozen samples and provided information not available in conventionally fixed samples. Mature haustoria of H. parasitica were distinctly pyriform in shape. A small collar of host cell wall material surrounded the neck of each haustorium near the host cell wall penetration site. The presence of callose in collars was demonstrated using immunogold labeling with a monoclonal antibody specific for (1→3)-β-glucans. The body of each haustorium was ensheathed by an invaginated portion of the invaded host-cell plasma membrane known as the extrahaustorial membrane. Lying between this membrane and the haustorial wall was a layer of electron-dense material known as the extrahaustorial matrix (EHM). The EHM typically was thicker at the distal end of a haustorium than at the proximal end. The surface of the EHM covered by the extrahaustorial membrane was highly irregular in outline. Considerable vesicular activity was observed in association with the extrahaustorial membrane.Key words: transmission electron microscopy, high-pressure freezing, haustoria, Peronospora parasitica.
Selective Inhibition of Cyclooxygenase-2 Enhances Platelet Adhesion in Hamster Arterioles In Vivo
Authors: Buerkle Martin A. , Lehrer Selim , Sohn Hae-Young , Conzen Peter , Pohl Ulrich , Krötz Florian
Published: September 2004

Background—

Selective inhibitors of cyclooxygenase-2 (Cox-2) are reported to cause cardiovascular side effects in patients at risk. However, direct proof of prothrombotic effects of these drugs is lacking. We investigated in the microcirculation in vivo whether selective inhibition of Cox-2 induces platelet activation.

Methods and Results—

The behavior of fluorescence-labeled human platelets was studied in hamster arterioles (dorsal skinfold chamber) by intravital microscopy. Transient platelet–vessel wall interactions (PVWIs), firm platelet adhesion to the vessel wall, and vessel occlusion after FeCl
3
-induced wall injury were analyzed as platelet activation parameters. In vitro experiments in human umbilical vein endothelial cells (HUVECs) were performed to assess specific effects of Cox-2 inhibition on platelet adhesion under shear stress (16 dyn/cm
2
) and on endothelial release of 6-ketoprostaglandin (PG) F
1α
. Selective inhibition of Cox-2 (NS-398, 0.5 mg/kg) increased platelet adhesion to the vessel wall in vivo (11.9±3.9 platelets/mm
2
; controls, 1.4±1.4 platelets/mm
2
,
P
<0.05) and platelet adhesion after ADP stimulation in vitro. PVWIs were significantly enhanced in NS-398–treated animals, which were reduced by platelet pretreatment with aspirin (5 mg/kg) or iloprost (1 nmol/L). Inhibition of Cox-2 reduced levels of 6-keto-PGF
1α
in vivo and in HUVEC supernatants. Time to occlusion after vessel wall injury was significantly shortened by NS-398 (125.4±13.6 seconds in NS-398–treated animals versus 270.8±46 seconds in controls;
P
<0.01).

Conclusions—

Selective inhibition of Cox-2 reduces 6-keto-PGF
1α
endothelial release, increases PVWIs, and increases firm platelet adhesion in hamster arterioles. Moreover, it leads to faster occlusion of damaged microvessels. Thus, selective inhibition of Cox-2 may trigger thrombotic events by diminishing the antiplatelet properties of the endothelium.
Left Ventricular Remodeling and Heart Failure in Diabetic Patients Treated With Primary Angioplasty for Acute Myocardial Infarction
Authors: Carrabba Nazario , Valenti Renato , Parodi Guido , Santoro Giovanni M. , Antoniucci David
Published: September 2004

Background—

Diabetes mellitus has been recognized as a strong predictor of heart failure (HF) in patients with acute myocardial infarction (AMI). However, considerable controversy exists regarding the pathogenetic mechanisms of HF after AMI in diabetic patients. We hypothesized that the increased incidence of HF in diabetic patients was associated with a greater propensity for left ventricular (LV) remodeling.

Methods and Results—

A series of 325 patients (42 diabetics) with AMI successfully treated with primary angioplasty underwent serial 2D echocardiography from admission to 1 and 6 months and 6-month angiography. No significant difference was found between diabetics and nondiabetics regarding baseline clinical, angiographic, and echocardiographic characteristics, as well as 6-month restenosis and reocclusion rates. At 6 months, a similar incidence of LV remodeling was observed in diabetics and nondiabetics (33% versus 25%;
P
=0.234), with similar patterns of changes in LV volumes and LV global and regional systolic function. At 5 years, the incidence of HF was higher in the diabetics (43% versus 20%,
P
=0.001). Diabetes was found to be an independent predictor of HF at 5 years (hazard ratio, 1.8;
P
=0.0366). However, LV remodeling was predictive of HF in the nondiabetics (
P
=0.023) but not in the diabetics (
P
=0.123). In a subgroup of patients, higher LV chamber stiffness (as assessed by echocardiography) was detected in the diabetics with HF.

Conclusions—

The more frequent progression to HF in the diabetics after AMI is not explained by a greater propensity for LV remodeling. Other factors, such as diastolic dysfunction, may play a role.
Medical Costs and Quality of Life 10 to 12 Years After Randomization to Angioplasty or Bypass Surgery for Multivessel Coronary Artery Disease
Authors: Hlatky Mark A. , Boothroyd Derek B. , Melsop Kathryn A. , Brooks Maria M. , Mark Daniel B. , Pitt Bertram , Reeder Guy S. , Rogers William J. , Ryan Thomas J. , Whitlow Patrick L. , Wiens Robert D.
Published: September 2004

Background—

Coronary bypass surgery (CABG) and angioplasty (PTCA) have been compared in several randomized trials, but data about long-term economic and quality-of-life outcomes are limited.

Methods and Results—

Cost and quality-of-life data were collected prospectively from 934 patients who were randomized in the Bypass Angioplasty Revascularization Investigation (BARI) and followed up for 10 to12 years. CABG had 53% higher costs initially, but the gap closed to <5% during the first 2 years; after 12 years, the mean cumulative cost of CABG patients was $123 000 versus $120 750 for PTCA, yielding a cost-effectiveness ratio of $14 300/life-year added. CABG patients experienced significantly greater improvement in their physical functioning for the first 3 years but not in later follow-up. Recurrent angina substantially reduced all quality-of-life measures throughout follow-up. Cumulative costs were significantly higher among patients with diabetes, heart failure, and comorbid conditions and among women; costs also were increased by angina, by the number of revascularization procedures, and among patients who died.

Conclusion—

Early differences between CABG and PTCA in costs and quality of life were no longer significant at 10 to 12 years of follow-up. CABG was cost-effective as compared with PTCA for multivessel disease.
Angiotensin Receptor Blockade With Candesartan Attenuates Atherosclerosis, Plaque Disruption, and Macrophage Accumulation Within the Plaque in a Rabbit Model
Authors: Johnstone Michael T. , Perez Alexandra S. , Nasser Imad , Stewart Robert , Vaidya Anand , Al Ammary Fawaz , Schmidt Ben , Horowitz Gary , Dolgoff Jennifer , Hamilton James , Quist William C.
Published: September 2004

Background—

Little is known about whether direct angiotensin receptor blockade can reduce atherosclerosis and plaque disruption. This study evaluated the effect of angiotensin receptor blockade on both the development of atherosclerosis and the disruption of plaque in a modified Constantinides animal model.

Methods and Results—

Twenty-eight New Zealand White rabbits underwent aortic balloon injury followed by a 1% cholesterol diet for 8 weeks. Thirteen rabbits received candesartan at 0.5 mg · kg
−1
· d
−1
beginning 2 days before aortic balloon injury and continued for the total 8 weeks of the cholesterol diet. The rabbits were then pharmacologically triggered and humanely killed, and their aortas were analyzed. The degree of atherosclerosis was determined by intima-media ratio of the infrarenal portion of the aorta. The frequency of intra-aortic thrombosis, a measure of plaque disruption, and the percentages of macrophage area and collagen-staining area of the plaque were determined. Candesartan-treated rabbits had less atherosclerosis (intima-media infrarenal aorta ratio of 1.18±0.08 versus 1.57±0.08 [mean±SEM] for the placebo group,
P
<0.001); fewer thrombi (3 of 13 versus 11 of 15;
P
<0.05); lower percentage area of macrophages to total plaque (18.8±2.7% versus 27±2.5%,
P
<0.05); and higher collagen to total plaque area (45±3% versus 35±2%,
P
<0.01).

Conclusions—

These results demonstrate that angiotensin receptor blockade attenuates the degree of atherosclerosis and reduces both plaque disruption and macrophage accumulation while increasing collagen deposition in the aortas of this animal model.
Survival After Coronary Revascularization Among Patients With Kidney Disease
Authors: Hemmelgarn Brenda R. , Southern Danielle , Culleton Bruce F. , Mitchell L. Brent , Knudtson Merril L. , Ghali William A.
Published: September 2004

Background—

The optimal approach to revascularization in patients with kidney disease has not been determined. We studied survival by treatment group (CABG, percutaneous coronary intervention [PCI], or no revascularization) for patients with 3 categories of kidney function: dialysis-dependent kidney disease, non–dialysis-dependent kidney disease, and a reference group (serum creatinine <2.3 mg/dL).

Methods and Results—

Data were derived from the Alberta Provincial Project for Outcomes Assessment in Coronary Heart Disease (APPROACH), which captures information on all patients undergoing cardiac catheterization in Alberta, Canada. Characteristics and patient survival in 662 dialysis patients (1.6%) and 750 non–dialysis-dependent kidney disease patients (1.8%) were compared with the remainder of the 40 374 patients (96.6%). For the reference group, the adjusted 8-year survival rates for CABG, PCI, and no revascularization (NR) were 85.5%, 80.4%, and 72.3%, respectively (
P
<0.001 for CABG versus NR;
P
<0.001 for PCI versus NR). Adjusted survival rates were 45.9% for CABG, 32.7% for PCI, and 29.7% for NR in the nondialysis kidney disease group (
P
<0.001 for CABG versus NR;
P
=0.48 for PCI versus NR) and 44.8% for CABG, 41.2% for PCI, and 30.4% for NR in the dialysis group (
P
=0.003 for CABG versus NR;
P
=0.03 for PCI versus NR).

Conclusions—

Compared with no revascularization, CABG was associated with better survival in all categories of kidney function. PCI was also associated with a lower risk of death than no revascularization in reference patients and dialysis-dependent kidney disease patients but not in patients with non–dialysis-dependent kidney disease. The presence of kidney disease or dependence on dialysis should not be a deterrent to revascularization, particularly with CABG.
N
-Acetylcysteine Treatment Normalizes Serum Tumor Necrosis Factor-α Level and Hinders the Progression of Cardiac Injury in Hypertensive Rats
Authors: Bourraindeloup Marie , Adamy Christophe , Candiani Gabriele , Cailleret Michel , Bourin Marie-Claude , Badoual Thierry , Su Jin Bo , Adubeiro Sylviane , Roudot-Thoraval Françoise , Dubois-Rande Jean-Luc , Hittinger Luc , Pecker Françoise
Published: September 2004

Background—

Studies in isolated cardiomyocytes showed that replenishment in cellular glutathione, achieved with the glutathione precursor
N
-acetylcysteine (NAC), abrogated deleterious effects of tumor necrosis factor-α (TNF-α).

Methods and Results—

We examined the ability of NAC to limit the progression of cardiac injury in the rat model of hypertension, induced by the nitric oxide synthase inhibitor
N
G
-nitro-
l
-arginine methyl ester (L-NAME) (50 mg/kg per day SC) and high-salt diet (HS) (8% NaCl). Four-week HS/L-NAME administration induced hypertension (193±8 versus 122±4 mm Hg for low-salt diet [LS] group) and left ventricular (LV) dysfunction, revealed by echocardiography and characterized by decreased LV shortening fraction (38±2% versus 49±4% for LS group;
P
<0.05) and decreased LV posterior wall thickening (49±3% versus 70±4% for LS group;
P
<0.05). LV dysfunction worsened further after 6-week HS/LNAME administration. Importantly, increase in serum TNF-α level was strongly correlated with shortening fraction decrease and cardiac glutathione depletion. NAC (75 mg/d) was given as a therapeutic treatment in a subgroup of HS/L-NAME animals during weeks 5 and 6 of HS/L-NAME administration. NAC treatment, which replenished cardiac glutathione, had no effect on hypertension but reduced LV remodeling and dysfunction, normalized serum TNF-α level, and limited activation of matrix metalloproteinases -2 and -9 and collagen deposition in LV tissues.

Conclusions—

These findings suggest that glutathione status determines the adverse effects of TNF-α in cardiac failure and that TNF-α antagonism may be achieved by glutathione supplementation.
Relation of Nonperfused Myocardial Volume and Surface Area to Left Ventricular Performance in Coronary Microembolization
Authors: Malyar Nasser M. , Lerman Lilach O. , Gössl Mario , Beighley Patricia E. , Ritman Erik L.
Published: September 2004

Background—

After occlusion of an epicardial artery, left ventricular (LV) dysfunction is closely related to the volume of nonperfused myocardium (NPM). The impact of coronary microembolization (ME) on LV function, however, is larger relative to the total volume of NPM. We hypothesized that the total surface area (SA), rather than the total volume, of NPM is the major determinant of ME-induced LV dysfunction.

Methods and Results—

We injected microspheres of 10-, 30-, or 100-μm diameter at each of 3 doses selectively into the left anterior descending coronary artery of 48 anesthetized pigs. Electron beam computed tomography (CT) was used to measure regional myocardial perfusion and changes in LV wall thickening (ΔWT) and stroke volume (ΔSV) after ME. At postmortem, a transmural “biopsy” of 1 to 2 cm
3
of embolized myocardium was imaged by micro-CT, resulting in 3D images that provided volumes and SAs of the individual nonperfused foci. Additionally, in 9 pigs, creatine phosphokinase (CK) activity in embolized myocardium was measured as an index of washout of substances from the NPM. After ME, ΔWT, ΔSV, and CK washout were correlated more closely with the total SA (
r
=0.95,
P
<0.001;
r
=0.68,
P
<0.01; and
r
=0.88,
P
=0.01, respectively) than with the total NPM volume (
r
=0.59,
P
>0.05; 0.46,
P
>0.05; and
r
=0.69,
P
=0.04, respectively).

Conclusion—

After coronary ME, LV dysfunction is more closely related to the total SA than to the total volume of nonperfused microregions in the myocardium.