bluuebunny/crossref_metadata_2025 huggingface dataset:
Ability of frequency doubling perimetry and scanning laser polarimetry to detect ocular hypertension and POAG in an Indian population
Authors: Sukumar S. , Balekuduru S. , Mani B. , Vijaya L.
Published: March 2003

Purpose:  To evaluate the ability of Frequency doubling perimetry (FDP) and scanning laser polarimetry (GDx) in the detection of Ocular hypertension (OHT) and Primary Open Angle Glaucoma (POAG) in an Indian population.

Methods:  Subjects were classified as being normal or having OHT or POAG (mild, moderate and severe) based on clinical findings and visual field results. A total of 104 eyes of 86 subjects who satisfied the inclusion criteria and completed the tests successfully were analysed. Sensitivity and specificity of N‐30 Full field FDP tests were analysed for OHT and three POAG groups. GDx parameters were compared between normal subjects and other groups.

Results:  When compared with normal subjects, superior‐based GDx parameters were significantly different (p < 0.05) in OHT and mild POAG. Average‐based parameters showed significant difference (p < 0.05) only in moderate and severe POAG. Among all the GDx parameters ‘The number’ (cut off value >19) showed significant results in OHT (sensitivity 66% and specificity 92%) and in POAG groups (sensitivity ≥88% and specificity ≥92%). OHT changes were detected by N 30 Full Threshold FDP test (sensitivity 22% and specificity 83%) and in mild (sensitivity 59% and specificity 87%), moderate (sensitivity 88% and specificity 96%) and severe (sensitivity 100% and specificity 100%) POAG groups when mean deviation (P < 5) was used as the cut off value.

Conclusion:  Both FDP and GDx are valid screening tools for detecting OHT and POAG. The ability of GDx in detecting OHT and POAG improved if normal subjects from the Indian population are used for comparison.
Within‐texture alignment improves human texture segmentation
Authors: Harrison S. J. , Keeble D. R. T.
Published: March 2003

Purpose:  Spatial arrangement has been shown to be a critical factor both in detection facilitation of a threshold target by collinear flankers and in detection of smooth chains within random arrays of suprathreshold elements. Here, we investigate the effect of alignment between texture elements on human texture perception.

Methods:  Texture displays, consisting of arrays of elements, were presented to observers for 100 ms. Trials were completed with both line elements and with Gabor patches. A discrimination task consisted of one stimulus presentation, and observers distinguished between two possible orthogonal orientations of a central block, which differed from the surround by the orientation of its elements. A detection task required observers to indicate in which of two presentations the central block was present. For both tasks, the degree of alignment within stimuli was varied either by increasing orthogonal offset between elements or by decreasing the length of chains of aligned elements. Both alterations result in an overall reduction of collinearity within the display. A close‐spaced and a far‐spaced condition were tested. Global element density was kept constant within all line trials and within all Gabor trials.

Results:  For nearly all conditions, alignment was found to improve thresholds. The effect was robust to orientational jitter up to a standard deviation of the array‐element population of 8°.

Conclusions:  Our results suggest that collinearity between elements results in both short and long‐range interactions, which contribute to the formation of a texture‐defined surface. Interactions between close‐spaced elements might be explicable in terms of a linear‐filter summation paradigm, but results for far‐spaced elements would definitely require additional mechanisms.
Retinal projections to the thalamus in albino frogs
Authors: Grant S. , Waller W. , Bhalla A. , Kennard C.
Published: March 2003

Melanin in the embryonic retinal pigment epithelium (RPE) is essential for normal development of the mammalian visual system: in albino and other mutant mammals lacking this pigment, many temporal retinal ganglion cells (RGCs) that usually project ipsilaterally misroute their axons across the optic chiasm to the opposite side of the brain. In human albinos, this misrouting results in higher visual centres receiving predominantly monocular input from the opposite eye and in defective binocular stereovision. The RPE–RGC signalling mechanisms that govern the chiasmatic pathway choices of ganglion cell axons are unknown, but may involve gap junctions, which are a conserved feature of the embryonic retina in all vertebrate classes.

To determine whether chiasmatic abnormalities also generalize to non‐mammalian pigment mutants, we compared the distribution of crossed and uncrossed retinal projections to the thalamus in normal and albino Xenopus frogs. In both phenotypes, retinal terminations from the opposite eye covered ∼80% of the neuropil of Bellonci and corpus geniculatum thalamicum (analogous to the mammalian lateral geniculate nuclei), with uncrossed inputs occupying ∼75 and 25%, respectively, of the two terminal fields. Ipsilateral projections originated from ∼3000 RGCs in the wild‐type and albino frogs, and in both phenotypes they were restricted to a ventrotemporal crescent comprising ∼40% of the total retinal area.

In sum, we found no evidence of chiasmatic misrouting in albino Xenopus, despite the fact that this species normally possesses retinal projections with a substantial ipsilateral component. Our findings support other recent evidence that a lack of RPE melanin leads to defective development of the retina and its central pathways only in mammals.
Does optic disc topography vary during office hours?
Authors: Gunvant P. , Broadway D. , Watkins R.
Published: March 2003

Purpose:  To investigate whether there is variation in optic disc topography as measured by the Heidelberg Retina Tomograph (HRT), in normals during office hours.

Methods:  Thirty normal subjects (22 females and 8 males, median age 28 years, range 18–58) underwent Goldmann tonometry and optic disc analysis with the HRT. Three HRT readings were taken at each visit and a mean topographic image (MTI) produced. Measurements were performed in the morning (07.00–09.00 hours) and were repeated later the same day (17.00–19.00 hours). We studied the following topographic parameters: cup‐to‐disc area ratio (CDR), rim volume (RV), cup shape measure (CSM), and retinal nerve fibre layer thickness (RNFLT) in relation to time of day and the change in intraocular pressure (IOP).

Results:  The median changes in the topographic parameters were as follows (a negative value indicates a larger value in the evening): CDR (median 0.001, 95% CI: −0.007 to 0.007), RV (median 0.003, 95% CI: −0.021 to 0.016), CSM (median: −0.003, 95% CI: −0.015 to 0.007) and RNFLT (median 0.006, 95% CI: −0.010 to 0.009). No parameter exhibited statistically significant change. The median morning IOP was 14 mmHg (95% CI: 13–16 mmHg) and was not significantly different (Wilcoxon's W = 234; p = 0.27) to evening IOP when it was 13 mmHg (95% CI: 12–15 mmHg). The median difference in IOP was 1 mmHg higher in the morning than the evening (range 6 mmHg higher in the morning to 4 mmHg higher in the evening). The parameter changes between the morning MTI and the evening MTI were independent of IOP changes using Kendall's tau statistic for each parameter.

Conclusions:  There was no variation in HRT parameters when measured during office hours. Small intraindividual changes in IOP do not significantly affect optic disc topography.
Effects of ethnic origin on pulsatile ocular blood flow
Authors: Gunvant P. , Broadway D. C. , Watkins R. J.
Published: March 2003

Purpose:  To study the effect of ethnicity on pulsatile ocular blood flow (POBF).

Methods:  Eighty subjects from the staff and student population at Anglia Polytechnic University were examined. Forty subjects (20 males, 20 females) were Asian (originating from the Indian subcontinent) and 40 (20 males, 20 females) were white people. The subjects underwent a complete ophthalmic examination including refraction, slitlamp examination and biomicroscopic fundoscopy. Subjects with ocular pathology were excluded from the study. Subjects underwent POBF measurement on a randomly selected eye with an Ocular Blood Flow Analyzer (Paradigm Medical Industries, Salt Lake City, UT, USA). The Analyzer probe was mounted on a slitlamp and all measurements were performed by an experienced observer (PG).

Results:  The median age of the Asian subjects was 22 years (males 22 years; females 22 years) and of the white people was 24 years (males 26 years; females 23 years). The racial groups were comparable for age (Mann–Whitney U = 686.5, p = 0.27), refraction (Mann–Whitney U = 735.5, p = 0.4658) and IOP (Mann–Whitney U = 856, p = 0.5899). The mean POBF values in the Caucasian and Asian groups were 1033 µL min−1 (95% CI: 940–1125 µL min−1) and 1061 µL min−1 (95% CI: 958–1165 µL min−1), respectively. The difference in POBF between the ethnic groups did not reach statistical significance (Mann–Whitney U = 0.07, p = 0.7987). Females had a higher mean POBF than males (Mann–Whitney U = 1163; p = 0.0005) but there was no interaction with race (two‐way anovaF = 1.09; p = 0.2997).

Conclusions:  There was no significant difference between the mean POBF values for subjects originating from the Indian subcontinent and Caucasian subjects. The previously reported gender difference in mean POBF was confirmed. We suggest that reported differences in POBF values in different races may arise from instrumental factors.
The use of critical flicker frequency (CFF) as a potential vision test prior to cataract surgery: a pilot study
Authors: Vianya M. , Douthwaite W. A. , Elliott D. B.
Published: March 2003

Background:  To determine whether a patient would benefit from cataract surgery, a pre‐operative evaluation of retinal visual function is required. Age‐related macular disease has been reported as the most important factor leading to poor outcome after cataract surgery. The critical flicker frequency (CFF) is a psychophysical test that measures temporal resolution properties in the visual system.

Purpose:  (1) To evaluate if CFF can be used as a tool to predict visual outcome after cataract surgery. (2) To assess if lens opacities and/or retinal damage affects CFF values. (3) To assess the optimal configuration for the CFF target in relation to stimulus size.

Methods:  Thirty‐two patients have been included in the pilot study. Subjects were divided into the following categories: cataract, central retinal disease, pseudophakes and cataract after pupil dilatation. CFF threshold measurements were obtained after optimal refraction and visual acuity measurement using a Bailey–Lovie logMAR chart. A staircase method was used to find the CFF threshold. For each subject, three different stimulus sizes were analysed.

Results:  Critical flicker frequency measurements were unaffected by the presence of cataract (p > 0.05). Pupil dilatation gave slight higher results in patients with cataracts, although this difference was not statistically significant (anovaF = 3.6, p = 0.07). A significant difference for the three targets sizes was found (anovaF = 41.94, p < 0.05). Retinal disease produced an insignificant decrease in CFF (p > 0.05, n = 5).

Conclusions:  Critical flicker frequency appears to be independent of the image degrading effects of cataract. Comparison of the means for the different conditions studied show a slight decrease in CFF measurement for retinal disease in comparison to the cataract group. However, more subjects are needed to determine the usefulness of CFF as a potential vision test.
Changes in short‐wavelength resolution acuity with age and defocus in the periphery: implications for relative ganglion cell loss
Authors: Anderson R. S. , Zlatkova M. B. , Coulter E. , Demirel S.
Published: March 2003

Purpose:  Resolution acuity is known to be sampling limited for achromatic gratings in peripheral vision. In addition, peripheral achromatic resolution is unaffected by defocus up to 3 D. We have also shown resolution for Short Wavelength Sensitive (SWS) system isolating gratings to be sampling limited in both the fovea and periphery. This means that measurements of peripheral resolution with either stimulus can potentially be used to estimate the density of the corresponding underlying retinal ganglion cell population. We wished to examine the effect of optical defocus on detection and resolution acuity for this stimulus and also determine how peripheral resolution declined with age for both the achromatic and SWS system.

Methods:  We measured detection and resolution for SWS‐isolating gratings in the fovea and at 20° eccentricity for optical defocus between 0 and 4 D. In addition we measured resolution acuity for both achromatic and SWS‐isolating gratings at 13° in four retinal locations in 50 normal subjects ranging in age from 12 to 70 years. Measurements of lens density (age‐related yellowing) were also made in subjects over 60 years of age.

Results:  Detection acuity was initially higher than resolution accompanied by observations of aliasing. Detection acuity declined steadily with defocus but SWS resolution acuity showed no decline until 1 D in the fovea and 3 D at 20°. Resolution acuity was higher for achromatic gratings than SWS‐isolating gratings at all ages and neither displayed any decline in performance until around 55 years. After this both declined in a parallel fashion at a rate of 10% per decade. The individual ratio of SWS/achromatic resolution (0.25) showed no correlation with increasing lens density.

Conclusions:  As resolution for both short‐wavelength and achromatic gratings is robust to optical attenuation and declines in a parallel fashion after 55 years there appears to be no selective loss of SWS‐driven ganglion cell density relative to achromatic density with age.
An Update on Exercise Therapy for Knee Osteoarthritis
Authors: Baker Kristin
Published: March 2003

Knee osteoarthritis (OA) is the most common joint disorder in the United States. In the elderly population, symptomatic knee OA accounts for more dependency in lower‐extremity tasks than any other disease. Treatments have generally targeted pain, assuming that disability would be lessened as a direct result of improvements in pain control. However, there is evidence that pain and disability have different determinants. Exercise has the potential to mitigate many of the factors that lead to disability. In 1995, on the basis of several small, positive studies, the American College of Rheumatology recommended strength training and aerobic exercise for the treatment of knee OA. In the past several years, a number of intervention studies on exercise have been published. It is notable that all of the recent exercise studies report positive effects on pain and/or disability, although there is considerable variability in the magnitude of the effect. This variability may be due to differences in study design, exercise protocols, and study participants. Further studies are needed to better define the mechanisms responsible for the positive effects of exercise and to formulate a clear, concise exercise protocol that may have the potential to become a public health intervention for knee OA.
Exercise for Disease Prevention in the Geriatric Population
Authors: Singh Maria A. Fiatarone
Published: March 2003

Abstract

Old age does not mitigate the importance of disease prevention as a primary therapeutic goal of healthcare practitioners. The rationale for the use of exercise as one way to achieve this goal rests upon the relationship of physical activity to a wide variety of chronic diseases, its role in risk‐factor reduction, its relationship to frailty, and its intersection with psychological health, nutritional status, and other health‐related behaviors. Evidence for the efficacy of exercise as a preventive strategy in the geriatric cohort comes from both large epidemiological studies and randomized clinical trials. The most promising are!as of benefit have to do with falls, type 2 diabetes, stroke,! coronary heart disease, osteoporosis, obesity, and depression. Primary‐prevention trials in healthy elders remain to be conducted for some disease outcomes; the same is true for vulnerable cohorts at high risk of incident disease, as there is a paucity of well‐designed clinical trials in those over the age of 75. Current knowledge suggests that various elements of the exercise prescription for disease prevention in the older adult should be individualized depending on patient profile and treatment goals. Variable emphasis on aerobic, resistive, and balance exercises is recommended, given the physiological specificity of adaptations to these modalities of activity. Concomitant behavioral strategies specific to sedentary elders and adapted to individual pragmatic needs, barriers to exercise adoption, and adherence are critical to the success of the exercise prescription in this setting.
Evaluation and Treatment of Iron Deficiency in Adults
Authors: Ross Elizabeth M.
Published: March 2003

Iron deficiency is prevalent in populations seen in primary practices. It is easily evaluated and treated, but often undiagnosed. Iron deficiency can lead not only to anemia but to decreased work capacity, abnormal neurotransmitter function, and altered immunologic and inflammatory defenses. Risk for iron deficiency is a function of iron loss, iron intake, iron absorption, and physiologic demands. Women of child‐bearing age are at especially high risk for iron deficiency due to ongoing menstrual blood losses. This article presents and describes a simple algorithm incorporating dietary considerations for evaluation and treatment of iron deficiency in primary care settings.
Regulation of αvβ3 and α5β1 integrin receptors by basic fibroblast growth factor and platelet‐derived growth factor‐BB in intrasynovial flexor tendon cells
Authors: Harwood Frederick L , Goomer Randal S , Gelberman Richard H , Silva Matthew J , Amiel David
Published: March 2003

Integrins are important players in soft tissue healing as molecules that mediate communication between cells and extracellular matrix. Thus, the regulation of the expression of these molecules would be important during wound repair. To explore the regulatory roles of specific growth factors on integrin expression by intrasynovial flexor tendon cells, the present study assessed the in vitro effects of basic fibroblast growth factor and platelet derived growth factor‐BB on expression of the α5β1 and αvβ3 integrins in these cells. Analyses were carried out at the transcriptional (reverse transcription‐polymerase chain reaction) and translational (immunohistochemistry) levels of cellular metabolism. Both types of analyses revealed increased expression of α5β1 and αvβ3 by tendon cells exposed to either basic fibroblast growth factor or platelet‐derived growth factor‐BB over a wide range of growth factor concentrations employed in the study. Semiquantitative reverse transcription‐polymerase chain reaction showed that, relative to control, basic fibroblast growth factor and platelet‐derived growth factor‐BB increased the expression of αv mRNA by 2‐and 3‐fold, respectively. Alpha 5 mRNA expression was also increased 3‐fold by basic fibroblast growth factor, and 2‐fold by platelet‐derived growth factor‐BB. We believe the results of this study are significant because the specific integrins affected are intimately involved in two events that have been shown to be important to intrasynovial flexor tendon healing, namely fibronectin deposition (α5β1) as part of the provisional matrix and angiogenesis/revascularization (αvβ3).
The proteolytic environment of chronic wounds
Authors: Yager Dorne R. , Nwomeh Benedict C.
Published: March 2003

A consistent feature of chronic leg and pressure ulcers is chronic inflammation associated with an elevated infiltration of neutrophils. Neutrophils and their proteases have been implicated in mediating the tissue damage associated with a variety of chronic inflammatory diseases. This review discusses our current understanding of the proteolytic enzymes found in chronic wounds and attempts to relate this information to the abundant presence of neutrophils. In addition, the implications that the proteolytic environment may have for current and future treatment strategies of chronic nonhealing wounds are discussed.
COMPARISON OF NORMAL HUMAN SKIN GENE EXPRESSION USING CDNA MICROARRAYS
Authors: Cole Jana , Tsou Raymond , Wallace Ken , Gibran Nicole , Isik Frank
Published: March 2003

Perturbations in normal wound healing may be traced to perturbations in gene expression in uninjured skin. In order to decipher normal and abnormal genetic responses to cutaneous injury, baseline gene expression in uninjured skin must first be defined. There is little data on gene expression profiles of normal human skin, i.e., which genes tend to be variable in expression and which tend to remain comparable. Therefore this study was designed to determine the degree of variability in human skin mRNA expression. Samples of normal skin were obtained from 9 healthy females undergoing breast reduction surgery. RNA was extracted, reverse transcribed into radiolabeled cDNA and hybridized onto cDNA microarrays of ∼4400 genes. Gene expression intensities from the 9 samples were normalized and compared as a ratio of highest/lowest expression intensity. Deviation greater than 2 standard deviations from the mean of each gene was used as a cut‐off. Seventy‐one genes (1.7%) were substantially variable in their expression. These included genes coding for transport proteins, gene transcription, cell signaling proteins, and cell surface proteins. We found minimal variability in the matrix genes, growth factor genes and other groups of genes that are the most often studied in wound healing research. A small but definite variability in gene expression across 9 samples of clinically comparable specimens of normal skin was detected. This is in keeping with clinical observations of the variability in normal skin across individuals. These data provide high‐throughput comparison of normal skin gene expression and suggest new molecules that may be studied in skin biology and perhaps, wound repair.
Delayed wound healing in aged rats is associated with increased collagen gel remodeling and contraction by skin fibroblasts, not with differences in apoptotic or myofibroblast cell populations
Authors: Ballas Christopher B. , Davidson Jeffrey M.
Published: March 2003

Aging has been anecdotally reported to result in prolonged wound healing. Measurement of punch biopsy wound closure in young (4 month old) and old (36 month old) rats indicated there was a significant delay in wound closure by old rats during the early phase of repair, after which closure rates were equivalent. The delay in granulation tissue accumulation in older animals could involve premature programmed cell death (apoptosis); however, apoptotic fibroblasts in sponge granulation tissue and tissue culture were less abundant in samples from old rats relative to young rats. Myofibroblasts express α‐smooth muscle actin, and they are believed to be important in wound contraction. There were no significant differences in overall abundance or distribution of α‐smooth muscle actin containing myofibroblasts in granulation tissue and in cultured granulation tissue fibroblasts regardless of the age of the donor rat. The spatial distribution of myofibroblasts and apoptotic cells was distinct. Fibroblasts from granulation tissue and skin explants were placed in a collagen gel contraction assay prior to the 5th passage to determine their in vitro contractility. While granulation tissue fibroblasts from young and old rats showed similar collagen gel contractility, skin fibroblasts from old rats displayed greater collagen gel contractile behavior than young skin fibroblasts. Greater gel contractility of fibroblasts from old rats appeared to result, in large part, from the ability of those cells to cause generalized gel degradation. Gelatin zymography indicated a greater abundance of matrix metalloproteinase‐2 in supernatants from gels containing skin fibroblasts from old rats. Taken together, these results suggest that the age‐associated healing delay in the rat may not be related to the appearance or abundance of distinct myofibroblast or apoptotic cell populations. Proteolysis may have a significant role in delayed wound healing in aged animals.
Corneal stem cells in review
Authors: DANIELS JULIE T. , DART JOHN K. G. , TUFT STEPHEN J. , KHAW PENG T.
Published: March 2003

The cornea provides the eye with protection and the refractive properties essential for visual acuity. The transparent epithelium is highly specialized with basal and stratified squamous cells that are renewed throughout life from a stem cell population. The stem cells are thought to reside at the corneal limbus and may be maintained by a variety of intrinsic and extrinsic factors such as the local environment, survival factors, and cytokines. A number of markers have been localized to the limbus in an attempt to identify stem cells; however, definite stem cell identification remains elusive. During homeostasis and following injury to the corneal epithelium, the limbal stem cells divide to produce daughter transient amplifying cells that proliferate, migrate, and differentiate to replace lost cells. However, this cannot occur if the stem cell population is depleted. Limbal stem cell deficiency then results in corneal re‐epithelialization by the neighboring conjunctiva, causing pain, poor vision, and even blindness. This review will focus on corneal epithelial stem cells in ocular surface repair and regeneration. The current knowledge of stem cell biology in the corneal epithelium, clinical consequences of stem cell deficiency, and therapeutic strategies aimed at reversing stem cell deficiency will be discussed.
Fibroblast proliferation due to exposure to a platelet concentrate in vitro is pH dependent
Authors: Liu Yawei , Kalén Anders , Risto Olof , Wahlström Ola
Published: March 2003

The influence of platelet‐rich plasma lysates on fibroblast proliferation was studied in culture. Cells were exposed to platelet lysates that had been preincubated at different pHs (5.0, 7.1, and 7.6). Proliferation was evaluated with the MTT assay and incorporation of [3H]thymidine into macromolecules, while type I collagen production was assayed by Western blotting. Enzyme‐linked immunosorbent assays were used to determine platelet‐derived growth factor and transforming growth factor‐β concentrations. Platelets preincubated in an acidic environment (pH 5.0) induced the highest degree of fibroblast proliferation, and the concentration of platelet‐derived growth factor in the different treated lysates was the highest at that particular pH. The concentration of transforming growth factor‐β, however, was lower after incubation at pH 5.0 than at either pH 7.1 or 7.6. These findings may be relevant to normal wound healing in vivo and useful in the treatment of wounds and delayed healing processes. (WOUND REP REG 2002;10:336–340)
Reepithelialization of experimental scalds effected by topically applied superoxide dismutase: controlled animal studies
Authors: Vorauer‐Uhl Karola , Fürnschlief Eckhard , Wagner Andreas , Ferko Boris , Katinger Hermann
Published: March 2003

Highly reactive metabolites, such as oxygen free radicals, initiate a cascade of inflammatory processes in thermally damaged skin, leading to enhanced tissue loss and delayed wound healing. The extent of tissue necrosis in the zone of stasis is of prognostic significance in the wound healing process. In this study, the effect of oxygen free radical removal by recombinant human‐Cu/Zn‐superoxide dismutase, given in three different formulations during the inflammatory postburn phase and wound repair, was examined. Recombinant human superoxide dismutase was either injected directly into the lesions, spread as enzyme‐containing gel onto the burned tissue, or encapsulated into liposomes consisting of 1,2 dipalmitoy‐sn‐glycero‐3‐phosphocholine, cholesterol and stearylamine, suspended into a hydrophilic gel and administered to burned animals immediately after trauma. Controls were treated with plain gel or kept untreated. Edema formation, size of lesions, deepening of necrosis, and reepithelialization were examined. Results indicate that superoxide dismutase treatment resulted in reduced and faster recruitment of edema formation, smaller wound sizes, and minor tissue necrosis compared to the controls, thus resulting in significantly faster reepithelialization after 3 weeks. These animal studies on the efficacy of liposomal oxygen free radical scavenger showed accelerated wound healing in all parameters tested. (WOUND REP REG 2002;10:366–371)
Thymosin β4 and a synthetic peptide containing its actin‐binding domain promote dermal wound repair in db/db diabetic mice and in aged mice
Authors: Philp Deborah , Badamchian Mahnaz , Scheremeta Brooke , Nguyen Mychi , Goldstein Allan L. , Kleinman Hynda K.
Published: March 2003

Impaired wound healing is a problem for immobilized patients, diabetics, and the elderly. Thymosin β4 has previously been found to promote dermal and corneal repair in normal rats. Here we report that thymosin β4 was also active in accelerating wound repair in full‐thickness dermal wounds in both db/db diabetic and aged mice. We found that thymosin β4 in either phosphate‐buffered saline or a hydrogel formulation is active in promoting dermal wound repair in normal rats. In diabetic mice, where healing is delayed, we found that wound contracture and collagen deposition were significantly increased in the mice treated with thymosin β4 in either phosphate buffered saline solution or a hydrogel formulation. No difference was observed in keratinocyte migration, with all of the diabetic animals showing almost complete coverage of the wound at 8 days. Wound healing in 26‐month‐old (aged) animals was significantly delayed. Thymosin β4 accelerated wound healing in these aged mice, with increases in keratinocyte migration, wound contracture, and collagen deposition. The hydrogel formulation generally showed similar wound healing activity with thymosin β4 in PBS. The actin‐binding domain of thymosin β4 duplicated in a seven‐amino acid synthetic peptide, LKKTETQ, was able to promote repair in the aged animals comparable to that observed with the parent molecule. These studies show that thymosin β4 is active for wound repair in models of impaired healing and may have efficacy in chronic wounds in humans. (WOUND REP REG 2003;11:19–24)
Reduction of scar formation in full‐thickness wounds with topical celecoxib treatment
Authors: Wilgus Traci A. , Vodovotz Yael , Vittadini Elena , Clubbs Elizabeth A. , Oberyszyn Tatiana M.
Published: March 2003

Adult wound repair occurs with an initial inflammatory response, reepithelialization, and the formation of a permanent scar. Although the inflammatory phase is often considered a necessity for successful adult wound healing, fetal healing studies have shown the ability to regenerate skin and to heal wounds in a scarless manner in the absence of inflammation. The cyclooxygenase‐2 (COX‐2) enzyme, a known mediator of inflammation, has been shown to contribute to a variety of inflammatory conditions and to the development of cancer in many organs. To examine the role of COX‐2 in the wound healing process, incisional wounds were treated topically with the anti‐inflammatory COX‐2 inhibitor celecoxib. Acutely, celecoxib inhibited several parameters of inflammation in the wound site. This decrease in the early inflammatory phase of wound healing had a significant effect on later events in the wound healing process, namely a reduction in scar tissue formation, without disrupting reepithelialization or decreasing tensile strength. Our data suggest that in the absence of infection, adult wound healing is able to commence with decreased inflammation and that anti‐inflammatory drugs may be used to improve the outcome of the repair process in the skin by limiting scar formation. (WOUND REP REG 2003;11:25–34)
Sapphirine in SW Sweden: a record of Sveconorwegian (–Grenvillian) late‐orogenic tectonic exhumation
Authors: MÖller
Published: March 2003

In the Sveconorwegian granulite region of SW Sweden, sapphirine occurs in reaction coronas in Mg‐ and Al‐rich kyanite eclogites which form parts of mafic complexes. Aluminous to peraluminous sapphirine forms symplectitic intergrowths with plagioclase±corundum±spinel after kyanite. Kyanite and omphacite were the main reactants in the formation of sapphirine. The sapphirine formed during decompression from the eclogite facies (P >15 kbar) through the high‐ to medium‐pressure granulite and upper amphibolite facies at c. 750 °C. Preserved growth zoning in garnet, frozen‐in reaction textures, and chemical disequilibrium suggest a rapid tectonic exhumation. Ductile deformation in the surrounding gneisses and parts of the mafic complex is characterized by foliation development, WNW–ESE stretching and dynamic recrystallization under granulite to upper amphibolite facies conditions, simultaneous with the sapphirine formation. This decompression, high‐grade re‐equilibration and associated deformation took place during the exhumation of the Sveconorwegian eclogites, bracketed between 969±14 and 956±7 Ma. Probable tectonic causes are late‐orogenic gravitational collapse and/or plate divergence following the Sveconorwegian–Grenvillian continent–continent collision. There are no indications of metastability of aluminous and peraluminous sapphirine in the decompressed kyanite eclogites; sapphirine is stable in amphibole‐poor and amphibolitized varieties, including rocks that have undergone dynamic recrystallization. Close similarities between rocks from different parts of the world with respect to reaction textures suggests that sapphirine+plagioclase‐forming reactions are a universal feature in high‐temperature decompressed kyanite eclogites.
Model for the development of kyanite during partial convective overturn of Archean granite–greenstone terranes: the Pilbara Craton, Australia
Authors: COLLINS  , VAN KRANENDONK*
Published: March 2003

Restricted occurrences of early, syn‐ and late‐kinematic kyanite adjacent to large domal batholiths in the Archean granite–greenstone terrane of the east Pilbara craton, Australia, are considered to result from partial convective overturn of the crust. The analogue models of Dixon & Summers (1983) and thermo‐mechanical models of Mareschal & West (1980), involving gravitionational overturn of dense greenstone crust that initially overlay sialic basement, successfully explain the geometry, dimension, kinematics and strain patterns of the batholiths and greenstone rims. Application of these models suggests that andalusite and sillimanite are the stable aluminosilicate polymorphs in domal crests and rims, where prograde clockwise P–T–t paths, with small pressure changes, should be recorded. Both aluminosilicates are predicted to overprint kyanite, which is observed locally around the east Pilbara domes. Kyanite is the predicted aluminosilicate polymorph in the deeper parts of domal rims and within sinking greenstone keels, reflecting rapid, near‐isothermal burial. The narrow zones of kyanite‐bearing schists adjacent to some batholiths in the Pilbara craton are metamorphosed, highly strained equivalents of altered felsic volcanic rocks in the low‐grade greenstone succession, dragged to mid‐crustal depths (6 kbar) during greenstone sinking. The schists rebounded as an arcuate tectonic wedge along the southern Mount Edgar batholith rim, during the later stages of doming, and were juxtaposed against regional, greenschist facies, low‐strain greenstones. Thus, kyanite was preserved: if the walls had remained at depth, it would have been overprinted by the higher‐temperature aluminosilicate polymorphs during thermal recovery.

Kyanite growth in the Pilbara craton is unlikely to have resulted from ballooning of plutons, mantled gneiss doming, metamorphic core complex formation, or early crustal overthickening. The typical subvertical foliations and lineations of the tectonic wedge suggest that subvertical fabrics extended to mid‐crustal depths (c. 20 km) before rebound, providing a three‐dimensional glimpse of Archean dome‐and‐keel structures. The general occurrence of large granitoid domes in Archean granite–greenstone terranes, restriction of rare kyanite to the adjacent, high‐strain batholith margins, and its absence from the batholiths, suggest that partial convective overturn of the crust may have been a common process at this early stage of Earth history.
The effects of accretion, erosion and radiogenic heat on the metamorphic evolution of collisional orogens
Authors: Huerta  , Royden  , Hodges
Published: March 2003

Petrological and thermochronological data provide our best record of the thermal structure of deeply eroded orogens, and, in principle, might be used to relate the metamorphic structure of an orogen to its deformational history. In this paper, we present a two‐dimensional thermal model of collisional orogens that includes the processes of accretion and erosion to examine the P–T  evolution of rocks advected through the orogen. Calculated metamorphic patterns are similar to those observed in the field; metamorphic temperatures, depths and ages generally increase with distance from the toe of the orogen; P–T  paths are anti‐clockwise, with rocks heating during burial and early stages of unroofing, followed by cooling during late‐stage unroofing. The results indicate that peak metamorphic temperatures within the core of a collisional orogen and the distance from the toe of an orogen to the metamorphic core can be related to the relative rates of accretion, erosion and plate convergence. Model orogens displaying high metamorphic temperatures (>600 °C) are associated with low ratios of accretion rate to plate convergence velocity and with high heat flow through the foreland. Model orogens with metamorphic cores far from the toe of the orogen are associated with high ratios of accretion rate to erosion rate. Calculated metamorphic gradients mimic steady‐state geotherms, and inverted thermal gradients can be preserved in the metamorphic record, suggesting reconsideration of the concept that the metamorphic record does not closely reflect geothermal gradients within an orogen.
Dehydration melting and devolatilization during exhumation of high‐grade metapelites: the Tatra Mountains, Western Carpathians
Authors: Janák  , Hurai  , Ludhová  , O’Brien  , Horn
Published: March 2003

Partial melting and retrogression related to Variscan tectonic exhumation have been recognized in the high‐grade metapelites of the Tatra Mountains, Western Carpathians. Staurolite and kyanite relics document an early stage of the prograde metamorphism at c. 600 °C and 9–10 kbar. An increase in temperature to >730 °C at 11–12 kbar resulted in partial melting and incipient migmatization in the stability field of kyanite. Further heating at decreasing pressure during the earliest stage of exhumation led to the dehydration‐melting of muscovite and biotite at >750–800 °C and 6–10 kbar, producing garnet‐bearing granite as leucosomes in migmatite. Subsequent cooling is documented by garnet resorption by biotite and sillimanite (a reversal of the prograde biotite dehydration‐melting reaction). This was followed by nearly isothermal decompression to c. 4–5 kbar producing cordierite and some melt due to biotite decomposition. Later nearly isobaric cooling led to cordierite pinitization and formation of orthoamphibole, chlorite and carbonates. Densities of primary, monophase CO2–N2 inclusions (0.69–1.06 g cm−3) from the migmatite leucosome are consistent with the near‐peak and retrograde conditions. Highly varying N2 contents (5–30 mol%) are thought to result from the nitrogen uptake in retrograde K‐bearing minerals, or dilution by CO2 liberated during interaction of melt‐derived water with metapelite graphite. The relatively high nitrogen content, not observed until now in migmatites, could have been inherited from the high‐pressure metamorphism stage. It is assumed that the water‐absent composition of fluid inclusions is not representative of the bulk water content (XH2O≤0.7), which was masked by mechanical separation of the CO2‐ and H2O‐dominated immiscible phases, and/or by post‐entrapment modifications of the fluid inclusions. Decompression and the final stage of exhumation were accomplished by top‐to‐the‐south thrusting as well as west–east (orogen‐parallel) extension. They were most probably related to regional uplift and gravitational collapse of thermally weakened Variscan crust.
Zoisite‐ and clinozoisite‐segregations in metabasites (Tauern Window, Austria) as evidence for high‐pressure fluid–rock interaction
Authors: Brunsmann  , Franz  , Erzinger  , Landwehr
Published: March 2003

High‐pressure zoisite‐ and clinozoisite‐bearing segregations are common in garnet‐ and albite‐bearing amphibolites of the Palaeozoic part of the Lower Schieferhülle, south‐central Tauern Window, Austria. The zoisite segregations (primary assemblage: Zo+Qtz+Cal) formed during an early to pre‐Hercynian high‐pressure event (P≫0.6 GPa, T =500–550 °C) by hydrofracturing as a result of protolith dehydration. Zoisite is growth zoned from Fe3+‐poor cores (Al2Fe=9 mol%) to Fe3+‐rich rims (17 mol%), and has high Sr, Pb and Ga contents and LREE‐enriched REE patterns, controlling the trace element budget of the segregations. Hercynian deformation at c. 0.7 GPa/600 °C kinked and cracked primary zoisite and enhanced breakdown into secondary zoisite (13 mol% Al2Fe), clinozoisite (40–55 mol% Al2Fe), albite (an<20), calcite and white mica during an Eoalpine high‐pressure event at 0.9–1.2 GPa/400–500 °C. The clinozoisite segregations (primary assemblage: Czo+Qtz+Omp+Ttn+Chl+Cal) are mm‐ to cm‐wide, vein‐like bodies, cross‐cutting fabric elements of the host garnet amphibolite. They formed during the Eoalpine high‐pressure event at 0.9–1.2 GPa/400–500 °C. During Alpine exhumation, omphacite was pseudomorphed by amphibole, albite, quartz and clinozoisite. Oxygen isotope data suggest equilibrium between host metabasite and zoisite segregations and indicate an internal fluid source and fluid buffering by the protolith. Mobility of P, Nb and LREE changed the protolith’s trace element composition in the vicinity of the zoisite segregations: Mobilization of LREE is evidenced by decreasing modal amounts of LREE‐rich epidote and decreasing LREE contents in LREE‐rich epidote towards the segregations, changing the REE patterns of the host metabasite from LREE‐enriched to LREE‐depleted. Tectonic discrimination diagrams, based on the trace element content of metabasites, should be applied with extreme caution.
Petrochemical constraints for dual origin of garnet peridotites from the Dabie‐Sulu UHP terrane, eastern‐central China
Authors: Zhang  , Liou  , Yang  , Yui
Published: March 2003

Garnet peridotites occur as lenses, blocks or layers within granulite–amphibolite facies gneiss in the Dabie‐Sulu ultra‐high‐pressure (UHP) terrane and contain coesite‐bearing eclogite. Two distinct types of garnet peridotite were identified based on mode of occurrence and petrochemical characteristics. Type A mantle‐derived peridotites originated from either: (1) the mantle wedge above a subduction zone, (2) the footwall mantle of the subducted slab, or (3) were ancient mantle fragments emplaced at crustal depths prior to UHP metamorphism, whereas type B crustal peridotite and pyroxenite are a portion of mafic–ultramafic complexes that were intruded into the continental crust as magmas prior to subduction. Most type A peridotites were derived from a depleted mantle and exhibit petrochemical characteristics of mantle rocks; however, Sr and Nd isotope compositions of some peridotites have been modified by crustal contamination during subduction and/or exhumation. Type B peridotite and pyroxenite show cumulate structure, and some have experienced crustal metasomatism and contamination documented by high 87Sr/86Sr ratios (0.707–0.708), low εNd(t) values (−6 to −9) and low δ18O values of minerals (+2.92 to +4.52). Garnet peridotites of both types experienced multi‐stage recrystallization; some of them record prograde histories. High‐P–T  estimates (760–970 °C and 4.0–6.5±0.2 GPa) of peak metamorphism indicate that both mantle‐derived and crustal ultramafic rocks were subducted to profound depths >100 km (the deepest may be ≥180–200 km) and experienced UHP metamorphism in a subduction zone with an extremely low geothermal gradient of <5 °C km−1.
Retrogression by deep infiltration of meteoric fluids into thrust zones during late‐orogenic rapid unroofing
Authors: Barker  , Bennett  , Boyce  , Fallick
Published: March 2003

Hypersaline (Na–Ca–Cl) fluids are associated with late‐stage quartz veining and retrogression of garnet, kyanite and other high P–T  phases in the vicinity of thrusts and major lithological boundaries in the Scandian nappes of the Troms‐Ofoten region, northern Norway. They record early Devonian fluid infiltration during rapid exhumation in the final stages of Caledonian orogenesis. The δ18O and δD characteristics of these late fluids provide compelling evidence for deep circulation of meteoric fluids. The sub‐greenschist to low greenschist facies retrogression (P=2±1 kbar; T =300–350 °C) suggests infiltration to depths of 7–9 km in a regime of supra‐hydrostatic fluid pressure. Peak metamorphic quartz veins and associated fluids have δD and δ18O characteristics consistent with a metamorphic origin (δD −47 to −75; δ18O+8.6 to +17.4). However, late quartz veins and associated fluids show a broad spread of δD from −42 to −148, interpreted in terms of meteoric fluid infiltration. Such negative δD values are only recorded in present‐day high‐latitude or high‐altitude settings, and since north Norway was in an equatorial setting (10° S) in the early Devonian, a high‐altitude origin is deduced. By calculation, and by comparison with modern examples, the early Devonian mountains of the north Norwegian Caledonides are interpreted to have had a topography in excess of 5 km. The deep circulation of surface waters is interpreted in terms of topographically driven flow, linked with a hydrothermal system induced by elevated geothermal gradients due to rapid uplift. Whilst the case for deep penetration of surface‐derived fluids has been promoted for Mesozoic and younger mountain belts, this study represents one of the first documented examples for a Palaeozoic orogenic belt. It suggests that many of the fundamental processes operating during the exhumation of mountain belts are similar irrespective of age.
Distinguishing between seafloor alteration and fluid flow during subduction using stable isotope geochemistry: examples from Tethyan ophiolites in the Western Alps
Authors: Miller  , Cartwright
Published: March 2003

Large amounts of fluid, bound up in the hydrated upper layers of the ocean crust, are consumed at convergent margins and released in subduction zones through devolatilization. The liberated fluids may play an integral role in subduction zone processes, including the generation of arc‐magmas. However, exhumed subduction zone rocks often record little evidence of large‐scale fluid flow, especially at deeper levels within the subduction zone. Basaltic pillows from the high‐pressure Corsican and Zermatt‐Saas ophiolites show a range of δ18O values that overall reflect seafloor alteration prior to subduction. However, comparison between the δ18O values of the cores and rims of the pillows suggests that the δ18O values of the pillow rims at least have been modified during subduction and high‐pressure metamorphism. Pillows that have not undergone high‐pressure metamorphism generally have rims with higher δ18O values than their cores, whereas the converse is the case in pillows that have undergone high‐pressure metamorphism. This reversal in the core to rim oxygen isotope relationship between unmetamorphosed and metamorphosed pillows is strong evidence for fluid–rock interaction occurring during subduction and high‐pressure metamorphism. However, the preservation of different δ18O values in the cores and rims of individual pillows and within and between different pillows suggests that fluid flow within the subduction zone was strongly channelled. Resetting of the δ18O values in the pillow rims was probably due to fluid‐hosted diffusion that occurred over relatively short time‐scales (<1 Myr).