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: Rationale and ObjectivesThe purpose of this study was to assess the impact on times of verification (TOVs) by a pager notification system (PNS) that informs physicians when reports are available for signature.: Materials and MethodsAn automated PNS was implemented in the authors'' department in November 2000. Monthly report verification times of each physician were collected for 3 months in the years before and after initiation of the PNS. Radiologists enrolled in the PNS and those who were not were assigned into two groups for analysis. Mean TOVs for the two sets of 3 months and for the two groups were calculated and differences recorded. Two-tailed t tests were used to assess for statistical differences between the groups.: ResultsTwenty-nine of 37 radiologists voluntarily enrolled in the PNS (group 1). Mean TOV was 26.75 hours (standard deviation [SD] = 17.76) for these physicians before and 14.48 hours (SD = 11.86) after the PNS was employed (P < .01). For those physicians who did not enroll in the PNS, mean TOV was 11.53 hours (SD = 5.55) before and 9.77 hours (SD = 9.86) after the PNS was employed (P = .33). Both the absolute and percentage reductions in TOVs were significantly greater for those physicians enrolled in the PNS than for those who were not (P = .035). Twenty-three of 29 (79%) physicians who used the PNS showed a reduction in their report turnaround times.: ConclusionLinking the PNS with the radiology information system to notify physicians of unsigned reports was effective in reducing report verification times. [Copyright &y& Elsevier]

Examines the handbook treatment and magazine use of the pronoun it. Categories of the pronoun; Number of times the pronoun was used in handbooks and magazines surveyed; Restriction on the use of the pronoun in some magazines.

Occupational exposure to inorganic acid mists containing sulfuric acid has been associated with increased laryngeal cancer. The primary objective of this review was to compile the literature regarding chronic toxicity and carcinogenicity of inorganic acid mists in laboratoryanimals. Several chronic toxicity studies had exposures of 1 year orlonger. Whereas numbers of animals were limited, no evidence of neoplastic or preneoplastic lesions was reported. Two studies evaluated the carcinogenicity of inorganic acid mists in rats; however, one was limited by a short duration of exposure and the other did not achievea maximum tolerated dose. A large lifetime study in hamsters evaluated the carcinogenicity of 100 mg/M3 sulfuric acid mist, aswell as its ability to act as a promoter or co-carcinogen for benzo(a)pyrene. No evidence of carcinogenic potential was shown. Although an increase in papillomas was noted in the benzo(a)pyrene + H2SO4 group, the co-carcinogenic or promoting potential was considered equivocal. Thus, no evidence from experimental animals strongly supports or refutes the induction of cancer by inorganic acid mists. A possible mechanism that could be associated with inorganicacid mist carcinogenicity relates to the genetic consequences of lowering the pH. Reduced pH can induce chromosomal aberrations, enhance depurination, and deamination of cytidine in DNA. This mechanism has not been evaluated in tissues of the respiratory tract. [ABSTRACT FROM AUTHOR]

Notch signaling is essential to maintain skeletal muscle stem cells in quiescence. However, the precise roles of different Notch receptors are incompletely defined. Here, we demonstrate a role for Notch3 (N3) in the self-renewal of muscle stem cells. We found that N3 is active in quiescent C2C12 reserve cells (RCs), and N3 over-expression and knockdown studies in C2C12 and primary satellite cells reveal a role in self-renewal. The Notch ligand Delta-like 4 (Dll4) is expressed by newly formed myotubes and interaction with this ligand is sufficient to maintain N3 activity in quiescent C2C12 RCs to prevent activation and progression into the cell cycle. Thus, our data suggest a model whereby during regeneration, expression of Dll4 by nascent muscle fibers triggers N3 signaling in associated muscle stem cells to recruit them to quiescence, thereby renewing the stem cell pool. Stem Cells 2018;36:458-466., (© 2017 AlphaMed Press.)

External reviews are used to evaluate a department on a routine basis or prior to reappointment or recruitment of a department chair. The Society of Chairs of Academic Radiology Departments (SCARD) developed a template that outlines important components of an external review report and a table that outlines the objective information that can be requested from the institution/department prior to the reviewer's site visit. The template is meant to facilitate a high-quality review and serve as a guide to a chair who is preparing for his/her first review, chairs who serve as external consultants, and institutional officials seeking review of a radiology department., (Copyright © 2014 AUR. Published by Elsevier Inc. All rights reserved.)

In facing future developments in health care, scenario planning offers a complementary approach to traditional strategic planning. Whereas traditional strategic planning typically consists of predicting the future at a single point on a chosen time horizon and mapping the preferred plans to address such a future, scenario planning creates stories about multiple likely potential futures on a given time horizon and maps the preferred plans to address the multiple described potential futures. Each scenario is purposefully different and specifically not a consensus worst-case, average, or best-case forecast; nor is scenario planning a process in probabilistic prediction. Scenario planning focuses on high-impact, uncertain driving forces that in the authors' example affect the field of radiology. Uncertainty is the key concept as these forces are mapped onto axes of uncertainty, the poles of which have opposed effects on radiology. One chosen axis was "market focus," with poles of centralized health care (government control) vs a decentralized private market. Another axis was "radiology's business model," with one pole being a unified, single specialty vs a splintered, disaggregated subspecialty. The third axis was "technology and science," with one pole representing technology enabling to radiology vs technology threatening to radiology. Selected poles of these axes were then combined to create 3 scenarios. One scenario, termed "entrepreneurialism," consisted of a decentralized private market, a disaggregated business model, and threatening technology and science. A second scenario, termed "socialized medicine," had a centralized market focus, a unified specialty business model, and enabling technology and science. A third scenario, termed "freefall," had a centralized market focus, a disaggregated business model, and threatening technology and science. These scenarios provide a range of futures that ultimately allow the identification of defined "signposts" that can suggest which basic features among the "possible futures" are playing out. Scenario planning provides for the implementation of appropriate constructed strategic responses. Scenarios allow for a pre-prepared game plan available for ready use as the future unfolds. They allow a deliberative response rather than a hastily constructed, urgent response., (Copyright © 2011 American College of Radiology. Published by Elsevier Inc. All rights reserved.)

To be effective for tissue repair, satellite cells (the stem cells of adult muscle) must survive the initial activation from quiescence. Using an in vitro model of satellite cell activation, we show that erbB1, erbB2 and erbB3, members of the EGF receptor tyrosine kinase family, appear on satellite cells within 6 h of activation. We show that signalling via erbB2 provides an anti-apoptotic survival mechanism for satellite cells during the first 24 h, as they progress to a proliferative state. Inhibition of erbB2 signalling with AG825 reduced satellite cell numbers, concomitant with elevated caspase-8 activation and TUNEL labelling of apoptotic satellite cells. In serum-free conditions, satellite cell apoptosis could be largely prevented by a mixture of erbB1, erbB3 and erbB4 ligand growth factors, but not by neuregulin alone (erbB3/erbB4 ligand). Furthermore, using inhibitors specific to discrete intracellular signalling pathways, we identify MEK as a pro-apoptotic mediator, and the erbB-regulated factor STAT3 as an anti-apoptotic mediator during satellite cell activation. These results implicate erbB2 signalling in the preservation of a full compliment of satellite cells as they activate in the context of a damaged muscle.

Rationale and Objectives: A near real-time and fully automatic method for calculation of the midsagittal plane (MSP) for magnetic resonance (MR) diffusion and perfusion images is introduced., Materials and Methods: The method is based on the Kullback-Leibler's (KL) measure quantifying the difference between two intensity distributions. The MSP is a sagittal plane with the highest KL measure. The method was validated quantitatively for 61 diffusion-weighted imaging (DWI), cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), peak height (PKHT), and time to peak (TPP) data sets of 11 stroke patients based on the ground truth provided by two raters., Results: Average angular errors are less than 1 degrees for DWI and less than 2 degrees for CBF and CBV. Average distance errors measured in the worst case (on the brain's bounding box) are less than 2.5 mm for DWI and less than 5 mm for CBF and CBV. This algorithmic accuracy is at the level of interrater variability. Results obtained for the other perfusions maps (MTT, PKHT, TTP) were inferior; therefore, processing of CBF or CBV is preferred for accurate and robust calculation of the MSP from perfusion maps. Calculation of the MSP takes about half a second on a standard computer., Conclusions: The proposed method is near real-time and fully automatic, and neither user interaction nor parameter setting is needed. It does not require preprocessing of data. The method potentially is useful in rapid and automated processing of MR stroke diffusion and perfusion images.

Skeletal muscle growth and regeneration are attributed to satellite cells - muscle stem cells resident beneath the basal lamina that surrounds each myofibre. Quiescent satellite cells express the transcription factor Pax7 and when activated, coexpress Pax7 with MyoD. Most then proliferate, downregulate Pax7 and differentiate. By contrast, others maintain Pax7 but lose MyoD and return to a state resembling quiescence. Here we show that Pax7 is able to drive transcription in quiescent and activated satellite cells, and continues to do so in those cells that subsequently cease proliferation and withdraw from immediate differentiation. We found that constitutive expression of Pax7 in satellite-cell-derived myoblasts did not affect MyoD expression or proliferation. Although maintained expression of Pax7 delayed the onset of myogenin expression it did not prevent, and was compatible with, myogenic differentiation. Constitutive Pax7 expression in a Pax7-null C2C12 subclone increased the proportion of cells expressing MyoD, showing that Pax7 can act genetically upstream of MyoD. However these Pax7-null cells were unable to differentiate into normal myotubes in the presence of Pax7. Therefore Pax7 may be involved in maintaining proliferation and preventing precocious differentiation, but does not promote quiescence.

Background and Purpose: The association of light to moderate alcohol consumption with risk of ischemic stroke remains uncertain, as are the roles of potentially mediating factors and modification by apolipoprotein E (apoE) genotype., Methods: We studied the prospective association of alcohol consumption and risk of ischemic stroke among 4410 participants free of cardiovascular disease at baseline in the Cardiovascular Health Study, a population-based cohort study of older adults from 4 US communities. Participants reported their consumption of alcoholic beverages yearly., Results: During an average follow-up period of 9.2 years, 434 cases of incident ischemic stroke occurred. Compared with long-term abstainers, the multivariate relative risks of ischemic stroke were 0.85 (95% CI, 0.63 to 1.13), 0.75 (95% CI, 0.53 to 1.06), 0.82 (95% CI, 0.51 to 1.30), and 1.03 (95% CI, 0.68 to 1.57) among consumers of <1, 1 to 6, 7 to 13, and > or =14 drinks per week (P quadratic trend 0.06). ApoE genotype appeared to modify the alcohol-ischemic stroke relationship (P interaction 0.08), with generally lower risks among drinkers than abstainers in apoE4-negative participants but higher risks among drinkers than abstainers among apoE4-positive participants. We could not identify candidate mediators among lipid, inflammatory, and prothrombotic factors., Conclusions: In this study of older adults, the association of alcohol use and risk of ischemic stroke was U-shaped, with modestly lower risk among consumers of 1 to 6 drinks per week. However, apoE genotype may modify this association, and even moderate alcohol intake may be associated with an increased risk of ischemic stroke among apoE4-positive older adults.

Background and Purpose: Magnetic resonance imaging (MRI) scans in the elderly commonly show white matter findings that may raise concerns. We sought to document incidence, manifestations, and predictors of worsening white matter grade on serial imaging., Methods: The Cardiovascular Health Study is a population-based, longitudinal study of 5888 people aged 65 years and older, of whom 1919 have had extensive initial and follow-up evaluations, including 2 MRI scans separated by 5 years. Scans were read without clinical information in standard side-by-side fashion to determine worsening white matter grade., Results: Worsening was evident in 538 participants (28%), mostly (85%) by 1 grade. Although similar at initial scan, participants with worsening white matter grade, compared with those without, experienced greater decline on modified Mini-Mental State examination and Digit-Symbol Substitution test (both P< or =0.001) after controlling for potential confounding factors, including occurrence of transient ischemic attack or stroke between scans. Independent predictors of worsening white matter grade included cigarette smoking before initial scan and infarct on initial scan. Otherwise, predictors differed according to white matter grade on initial scan. For low initial grade, increased age, increased diastolic blood pressure, increased high-density lipoprotein cholesterol, and decreased low-density lipoprotein cholesterol were associated with increased risk of worsening. For high initial grade, any cardiovascular disease and low ankle-arm index were associated with decreased risk of worsening, whereas use of diuretics and statins were associated with increased risk., Conclusions: Worsening white matter grade on serial MRI scans in elderly is common, is associated with cognitive decline, and has complex relations with cardiovascular risk factors.

Most muscle originates from the myotomal compartment of the somites, paired structures flanking the neural tube. Whereas vertebrate embryos show molecular and morphological asymmetry about the left-right body axis, somitic myogenesis is thought to occur symmetrically. Here, we provide the first evidence that myotome pairs are transiently left-right asymmetric, with higher expression of alpha-skeletal actin and myosin light chain 3F (MLC3F) on the left side between embryonic day 9.5-10.25. In iv mutants with situs inversus, the asymmetric expression of alpha-skeletal actin and MLC3F was inverted, showing that this process is regulated by global left-right axis cues, initiated before gastrulation. However, although left-sided identity is later maintained by Pitx2 genes, we found that Pitx2c null embryos have normal left-biased expression of alpha-skeletal actin and MLC3F. Myotome asymmetry, therefore, is downstream of the iv mutation but upstream of, or unrelated to, the Pitx2c pathway., (Copyright (c) 2004 Wiley-Liss, Inc.)

Heparin-binding EGF-like growth factor (HB-EGF) is a potent mitogen and chemoattractant for diverse cell types including, keratinocytes, fibroblasts and vascular smooth muscle cells. In adult mice, skeletal muscle and endothelial cells prominently express HB-EGF, although analysis of embryonic expression has been limited to studies of heart and kidney development. Here we survey HB-EGF mRNA expression in E7.5-E15 mouse embryos and show that HB-EGF is expressed in branchial arches, limb buds and, transiently, in mature somites between E9.25 and E11. This somitic expression is restricted to the myotomal compartment. Intriguingly, within myotome pairs, the expression of HB-EGF is stronger on the left side of the body, whilst cognate receptors, ErbB1 and ErbB4, are symmetrically expressed in left and right somite pairs. In iv/iv mutant embryos, with inverted left-right body axis, the expression of HB-EGF was also inverted, now being stronger in myotomes on the right side of the body. Thus, the expression of HB-EGF in myotome pairs is regulated by global cues that define the left-right body axis.

The myogenic regulatory factor Myf5 is integral to the initiation and control of skeletal muscle formation. In adult muscle, Myf5 is expressed in satellite cells, stem cells of mature muscle, but not in the myonuclei that sustain the myofibre. Using the Myf5(nlacZ/+) mouse, we now show that Myf5 is also constitutively expressed in muscle spindles-stretch-sensitive mechanoreceptors, while muscle denervation induces extensive reactivation of the Myf5 gene in myonuclei. To identify the elements involved in the regulation of Myf5 in adult muscle, we analysed reporter gene expression in a transgenic bacterial artificial chromosome (BAC) deletion series of the Mrf4/Myf5 locus. A BAC carrying 140 kb upstream of the Myf5 transcription start site was sufficient to drive all aspects of Myf5 expression in adult muscle. In contrast, BACs carrying 88 and 59 kb upstream were unable to drive consistent expression in satellite cells, although expression in muscle spindles and reactivation of the locus in myonuclei were retained. Therefore, as during development, multiple enhancers are required to generate the full expression pattern of Myf5 in the adult. Together, these observations show that elements controlling adult Myf5 expression are genetically separable and possibly distinct from those that control Myf5 during development. These studies are a first step towards identifying cognate transcription factors involved in muscle stem cell regulation.

Background: Poor survival of grafted cells is a major factor hindering the therapeutic effect of cell transplantation; however, the causes of cell death remain unclear. We hypothesized that interleukin-1beta (IL-1beta) might play a role in the acute inflammatory response and graft death after cell transplantation and that inhibition of IL-1beta might improve graft survival., Methods and Results: 14C-labeled male skeletal muscle precursor cells were implanted into female mouse hearts by direct intramuscular injection. The amount of 14C-label provides an estimate of the surviving cell number, whereas the amount of male-specific Smcy gene measured by polymerase chain reaction indicates the total (surviving+proliferated) number of donor-derived cells. At 10 minutes after implantation, 44.8+/-2.4% of the grafted cells survived and this steadily decreased to 14.6+/-1.1% by 24 hours, and to 7.9+/-0.6% by 72 hours (n=6 in each point). Proliferation of the surviving cells, which began after 24 hours, resulted in an increase in the total cell number from 15.5+/-0.8% at 24 hours to 24.4+/-1.6% at 72 hours. Acute inflammation was prominent at 24 hours and was reduced by 72 hours, in parallel with IL-1beta expression. Administration of anti-IL-1beta antibody improved graft survival at both 24 (25.6+/-1.6%) and 72 hours (14.8+/-1.1%) and resulted in a 2-fold increase in the total cell number at 72 hours (45.8+/-2.4%). The effects of IL-1beta inhibition corresponded with a reduced inflammatory response., Conclusions: IL-1beta is involved in acute inflammation and graft death after direct intramyocardial cell transplantation. Targeted inhibition of IL-1beta may be a useful strategy to improve graft survival.

Growth, repair, and regeneration of adult skeletal muscle depends on the persistence of satellite cells: muscle stem cells resident beneath the basal lamina that surrounds each myofiber. However, how the satellite cell compartment is maintained is unclear. Here, we use cultured myofibers to model muscle regeneration and show that satellite cells adopt divergent fates. Quiescent satellite cells are synchronously activated to coexpress the transcription factors Pax7 and MyoD. Most then proliferate, down-regulate Pax7, and differentiate. In contrast, other proliferating cells maintain Pax7 but lose MyoD and withdraw from immediate differentiation. These cells are typically located in clusters, together with Pax7-ve progeny destined for differentiation. Some of the Pax7+ve/MyoD-ve cells then leave the cell cycle, thus regaining the quiescent satellite cell phenotype. Significantly, noncycling cells contained within a cluster can be stimulated to proliferate again. These observations suggest that satellite cells either differentiate or switch from terminal myogenesis to maintain the satellite cell pool.

Background and Purpose: We have previously reported that several "silent" infarcts found on magnetic resonance imaging (MRI) were a risk factor for stroke. Several recent reports have shown that high white matter grade (WMG) and increasing WMG over time were risk factors for stroke. We tested the hypothesis that high WMG > or =2 was a predictor of risk for stroke, independent of other risk factors., Methods: We examined the extent of white matter hyperintensity on cranial MRI of 3293 participants from the Cardiovascular Health Study (CHS). The degree of white matter hyperintensity was graded from least severe (grade=0) to most severe (grade=9). Participants were followed-up for an average of 7 years for the occurrence of a stroke. Clinical stroke diagnoses were based on hospital records reviewed by an adjudication committee expert in stroke diagnosis. During this period, 278 strokes occurred. Results The relative risk of stroke increased significantly as the WMG increased. The risk of stroke was 2.8% per year for participants with high WMG (grades > or =5), compared with only 0.6% for participants with grades 0 to 1.Conclusions The risk of stroke with high WMG is independent of traditional stroke risk factors and persists when controlling for MRI infarcts, another subclinical imaging marker of cerebrovascular disease. Assessment of white matter disease may be valuable in assessing future risk of stroke.

Survival and proliferation of skeletal myoblasts within the cardiac environment are crucial to the therapeutic efficacy of myoblast transplantation to the heart. We have analyzed the early dynamics of myoblasts implanted into the myocardium and investigated the mechanisms underlying graft attrition. At 10 min after implantation of [14C]thymidine-labeled male myoblasts into female mice hearts, 14C measurement showed that 39.2 +/- 3.0% of the grafted cells survived, and this steadily decreased to 16.0 +/- 1.7% by 24 h and to 7.4 +/- 0.9% by 72 h. PCR of male-specific Smcy gene calculated that the total (surviving plus proliferated) number of donor-derived cells was 18.3 +/- 1.6 and 23.3 +/- 1.3% at 24 and 72 h, respectively, indicating that proliferation of the surviving cells began after 24 h. Acute inflammation became prominent by 24 h and was reduced by 72 h as indicated by myeloperoxidase activity and histological findings. Multiplex RT-PCR revealed corresponding changes in IL-1beta, TGF-beta, IL-6, and TNF-alpha expression. Treatment with CuZn-superoxide dismutase attenuated the initial rapid death and resulted in enhanced cell numbers afterward, giving a twofold increased total number at 72 h compared with the nontreatment. This effect was associated with reduced inflammatory response, suggesting a causative role for superoxide in the initial rapid graft death and subsequent inflammation. These data describe the early dynamics of myoblasts implanted into the myocardium and suggest that initial oxidative stress and following inflammatory response may be important mechanisms contributing to acute graft attrition, both of which could be potential therapeutic targets to improve the efficiency of cell transplantation to the heart.

Study Objectives: To examine whether sleep-disordered breathing is associated with white matter disease in the brainstem., Design: A population-based longitudinal study., Setting: Allegheny County, PA; Sacramento County, CA; and Washington County, MD., Patients or Participants: A total of 789 individuals, aged 68 years or older, drawn from the Sleep Heart Health Study., Interventions: N/A., Measurements and Results: The participants underwent home polysomnography in 1995-1998 and cerebral magnetic resonance imaging in both 1992-1993 and 1997-1998. The apnea-hypopnea index was not associated with white matter disease in the brainstem, with or without adjusting for age, sex, race, community, body mass index, smoking status, alcohol use, systolic blood pressure, and the use of antihypertensive medication. In contrast, the arousal index (number of arousals per hour of sleep) was inversely associated with brainstem white matter disease (odds ratio = 0.75 for a SD increase in the arousal index, 95% confidence interval: 0.62, 0.92)., Conclusions: The frequency of apneas and hypopneas was not associated with brainstem white matter disease in these older adults. A unique relationship with arousal frequency suggests that ischemic changes in the brainstem may be associated with arousals during sleep.

After myocardial infarction (MI), adverse remodeling with left ventricular (LV) dilatation is a major determinant of poor outcome. Skeletal myoblast (SkM) implantation improves cardiac function post-MI, although the mechanism is unclear. IL-1 influences post-MI hypertrophy and collagen turnover and is implicated in SkM death after grafting. We hypothesized that SkM expressing secretory IL-1 receptor antagonist (sIL-1ra) at MI border zones would specifically attenuate adverse remodeling and exhibit improved graft cell number. Stable murine male SkM lines (5 x 10(5) cells), expressing or nonexpressing (cont) for sIL-1ra, were implanted into infarct border zones of female nude mice immediately after left coronary artery occlusion. LV ejection fraction (LVEF), end-diastolic diameter, and transmitral peak early/late (E/A) flow velocity ratio were determined by echocardiography. Cardiac myocyte hypertrophy and fibrosis were assessed by morphometry, picrosirius red staining, and hydroxyproline assay. At 3 weeks, cont-SkM-engrafted hearts showed reduced hypertrophy, improved LVEF (55.7 +/- 1.2% vs. MI-only: 40.3 +/- 2.9%), and preserved E/A ratios. sIL-1ra-SkM implantation enhanced these effects (LVEF, 67.0 +/- 2.3%) and significantly attenuated LV dilatation (LV end-diastolic diameter, 4.0 +/- 1.1 mm vs. cont-SkM, 4.5 +/- 1.2 mm vs. MI-only, 4.8 +/- 1.8 mm); this was associated with greater graft numbers, as shown by PCR for male-specific smcy gene. Enzyme zymography showed attenuated matrix metalloproteinase-2 and -9 up-regulation post-MI by either donor SkM type, although infarct-remote zone collagen was reduced only with sIL-1ra-SkM. These results suggest that SkM implantation improves cardiac function post-MI by modulation of adverse remodeling, and that this effect can be significantly enhanced by targeting IL-1 as a key upstream regulator of both adverse remodeling and graft cell death.

Demonstration of the importance of the paired box transcription factor Pax7 for the murine myosatellite cell population, with persistent expression in mature skeletal muscle, prompted us to investigate the distribution of Pax7 protein in biopsy samples of normal and pathological human skeletal limb muscle. Immunostaining for M-cadherin, an adhesion molecule present at the interface between myofibre and satellite cell, and the characteristic position adjacent to the muscle fibre and beneath the fibre's basement membrane were used to identify satellite cells. Anti-Pax7 reactivity was found in the majority of satellite cells but a small population was Pax7 negative. Neither could we identify Pax7-positive nuclei in freshly regenerating myotubes or in presumed myoblasts in these biopsies. Similarly, in myogenic cell cultures derived from the explantation of human foetal muscle Pax7 expression was low or undetectable at the proliferative myoblast stage but it became prominent in an increasing proportion of mononucleate cells after the induction of differentiation. This expression was, however, restricted to mononucleate cells; it did not persist into the differentiation stage of newly formed multinucleate myotubes. Despite this, in the biopsy samples, we occasionally found Pax7-positive nuclei in muscle fibres that seemed to be undergoing degenerative changes. Most of these were found to be the nuclei of cells engaged in focal regenerative processes, but Pax7 re-expression by myonuclei "in distress" cannot be ruled out entirely.

Background and Purpose: The relevance of cavernous carotid artery calcification on unenhanced CT scans of the brain has recently been investigated against the backdrop of the widespread implementation of coronary artery calcification scoring. We sought to determine whether the degree of cavernous carotid artery calcification correlated with scores of white matter hyperintensity seen on MR images. In so doing, we sought to establish a relative risk for future stroke on the grade of carotid calcification., Methods: Neuroradiologic findings in 187 patients who underwent CT and MR imaging examinations within 1 month of each other were retrospectively reviewed. The degree of circumferential calcification and thickness of calcification were graded for the cavernous carotid arteries on the basis of CT findings. Using the scale developed by the Cardiovascular Health Study, the white matter was graded for degree of disease on the basis of MR findings. Correlation tests and regression analyses were performed to determine the impact of age, race, and sex on results., Results: Although the cavernous carotid calcification scores and the MR imaging white matter scores showed good correlation (P <.001), the effect was mediated by age. With age factored in as a covariant, no correlation was shown between CT calcification scores and MR imaging white matter scores. Sex had no effect, but African American study participants had worse MR imaging white matter scores than did white participants., Conclusion: After adjusting for age, cavernous carotid calcification grades and MR imaging white matter scores do not show a significant correlation. The relative risk for future stroke cannot be predicted from cavernous carotid calcifications.

The satellite cell compartment provides skeletal muscle with a remarkable capacity for regeneration. Here, we have used isolated myofibers to investigate the activation and proliferative potential of satellite cells. We have previously shown that satellite cells are heterogeneous: the majority express Myf5 and M-cadherin protein, presumably reflecting commitment to myogenesis, while a minority is negative for both. Although MyoD is rarely detected in quiescent satellite cells, over 98% of satellite cells contain MyoD within 24 h of stimulation. Significantly, MyoD is only observed in cells that are already expressing Myf5. In contrast, a minority population does not activate by the criteria of Myf5 or MyoD expression. Following the synchronous activation of the myogenic regulatory factor+ve satellite cells, their daughter myoblasts proliferate with a doubling time of approximately 17 h, irrespective of the fiber type (type I, IIa, or IIb) from which they originate. Although fast myofibers have fewer associated satellite cells than slow, and accordingly produce fewer myoblasts, each myofiber phenotype is associated with a complement of satellite cells that has sufficient proliferative potential to fully regenerate the parent myofiber within 4 days. This time course is similar to that observed in vivo following acute injury and indicates that cells other than satellite cells are not required for complete myofiber regeneration.