Multi-year dynamics of ranavirus, chytridiomycosis, and co-infections in a temperate host assemblage of amphibians

Chytridiomycosis and ranavirosis are 2 emerging infectious diseases that have caused significant global amphibian decline. Although both have received much scrutiny, little is known about interactions between the 2 causative agents Batrachochytrium dendrobatidis (Bd) and ranavirus (Rv) at the individual host and population levels. We present the first longitudinal assessment of Bd, Rv, and co-infections of a temperate amphibian assemblage in North America. From 2012 to 2016, we assessed the temporal oscillations of Bd, Rv and co-infection dynamics in a sample of 729 animals representing 13 species. Bd, Rv, and co-infected amphibians were detected during all 5 yr. Bd, Rv, and co-infection prevalence all varied annually, with the lowest instances of each at 2.1% (2013), 7.9% (2016), and 0.6% (2016), respectively. The highest Bd, Rv, and co-infection prevalence were recorded in 2012 (26.8%), 2016 (38.3%), and 2015 (10.3%), respectively. There was no association between Bd or Rv infection prevalence and co-infection, either when assessing the entire amphibian assemblage as a whole (odds ratio 1.32, 95% CI: 0.83-2.1, p = 0.29) or within species for amphibians that were more numerically represented (n > 40, p > 0.05). This suggests neither Bd nor Rv facilitate host co-infections within the sampled host assemblage. Instead, the basis for co-infections is the spatiotemporal distribution of both pathogens. Despite lack of interplay between Bd and Rv in this population, our study highlights the importance of considering numerous pathogens that may be present within amphibian habitats in order to properly anticipate interactions that may have direct bearing on disease outcomes.

Sonographic assisted diagnosis and treatment of bilateral gastrocnemius tendon rupture in a Labrador retriever repaired with fascia lata and polypropylene mesh

This case report describes a four-year-old, eighty-five pound, male neutered Labrador retriever that was admitted with unilateral lameness and clinical findings consistent with a unilateral gastrocnemius tendon rupture. A prior history of trauma was not identified. Ultrasonagraphic evaluation revealed bilateral gastrocnemius tendon defects in which approximately 80% of the tendon was ruptured on the clinically normal side, yet mechanical function and anatomical length were not apparently altered. Bilateral surgical repair was performed utilizing primary tendon reconstruction, supported by fascia lata, autograft and polypropylene mesh. The repairs were protected with rigid casts for two weeks following surgery, and replaced with orthotics through the complete recovery period. Orthotics provided semi-rigid support and allowed removal for controlled intermittent physical therapy. This surgical repair technique, combined with orthotic support, allowed for early mobilization and good ultimate outcome for a complicated bilateral condition.

Vimentin Intermediate Filaments Template Microtubule Networks to Enhance Persistence in Cell Polarity and Directed Migration

Increased expression of vimentin intermediate filaments (VIFs) enhances directed cell migration, but the mechanism behind VIFs' effect on motility is not understood. VIFs interact with microtubules, whose organization contributes to polarity maintenance in migrating cells. Here, we characterize the dynamic coordination of VIF and microtubule networks in wounded monolayers of retinal pigment epithelial cells. By genome editing, we fluorescently labeled endogenous vimentin and α-tubulin, and we developed computational image analysis to delineate architecture and interactions of the two networks. Our results show that VIFs assemble an ultrastructural copy of the previously polarized microtubule network. Because the VIF network is long-lived compared to the microtubule network, VIFs template future microtubule growth along previous microtubule tracks, thus providing a feedback mechanism that maintains cell polarity. VIF knockdown prevents cells from polarizing and migrating properly during wound healing. We suggest that VIFs' templating function establishes a memory in microtubule organization that enhances persistence in cell polarization in general and migration in particular.

Abnormal intermediate filament organization alters mitochondrial motility in giant axonal neuropathy fibroblasts

GAN patient cells have abnormal aggregates of vimentin intermediate filaments, to which mitochondria appear to be tethered. Motility of mitochondria, but not lysosomes, is inhibited in these cells. Transfection with wild-type gigaxonin (the protein mutated in this disease) disperses these aggregates and bundles, and mitochondrial motility returns to normal.

Giant axonal neuropathy (GAN) is a rare disease caused by mutations in the GAN gene, which encodes gigaxonin, an E3 ligase adapter that targets intermediate filament (IF) proteins for degradation in numerous cell types, including neurons and fibroblasts. The cellular hallmark of GAN pathology is the formation of large aggregates and bundles of IFs. In this study, we show that both the distribution and motility of mitochondria are altered in GAN fibroblasts and this is attributable to their association with vimentin IF aggregates and bundles. Transient expression of wild-type gigaxonin in GAN fibroblasts reduces the number of IF aggregates and bundles, restoring mitochondrial motility. Conversely, silencing the expression of gigaxonin in control fibroblasts leads to changes in IF organization similar to that of GAN patient fibroblasts and a coincident loss of mitochondrial motility. The inhibition of mitochondrial motility in GAN fibroblasts is not due to a global inhibition of organelle translocation, as lysosome motility is normal. Our findings demonstrate that it is the pathological changes in IF organization that cause the loss of mitochondrial motility.

Methods for Determining the Cellular Functions of Vimentin Intermediate Filaments

The type III intermediate filament protein vimentin was once thought to function mainly as a static structural protein in the cytoskeleton of cells of mesenchymal origin. Now, however, vimentin is known to form a dynamic, flexible network that plays an important role in a number of signaling pathways. Here, we describe various methods that have been developed to investigate the cellular functions of the vimentin protein and intermediate filament network, including chemical disruption, photoactivation and photoconversion, biolayer interferometry, soluble bead binding assay, three-dimensional substrate experiments, collagen gel contraction, optical-tweezer active microrheology, and force spectrum microscopy. Using these techniques, the contributions of vimentin to essential cellular processes can be probed in ever further detail.

Intermediate Filaments Play a Pivotal Role in Regulating Cell Architecture and Function

Intermediate filaments (IFs) are composed of one or more members of a large family of cytoskeletal proteins, whose expression is cell- and tissue type-specific. Their importance in regulating the physiological properties of cells is becoming widely recognized in functions ranging from cell motility to signal transduction. IF proteins assemble into nanoscale biopolymers with unique strain-hardening properties that are related to their roles in regulating the mechanical integrity of cells. Furthermore, mutations in the genes encoding IF proteins cause a wide range of human diseases. Due to the number of different types of IF proteins, we have limited this short review to cover structure and function topics mainly related to the simpler homopolymeric IF networks composed of vimentin, and specifically for diseases, the related muscle-specific desmin IF networks.

The Sec7 guanine nucleotide exchange factor GBF1 regulates membrane recruitment of BIG1 and BIG2 guanine nucleotide exchange factors to the trans-Golgi network (TGN)

Three Sec7 guanine nucleotide exchange factors (GEFs) activate ADP-ribosylation factors (ARFs) to facilitate coating of transport vesicles within the secretory and endosomal pathways. GBF1 recruits COPI to pre-Golgi and Golgi compartments, whereas BIG1 and BIG2 recruit AP1 and GGA clathrin adaptors to the trans-Golgi network (TGN) and endosomes. Here, we report a functional cascade between these GEFs by showing that GBF1-activated ARFs (ARF4 and ARF5, but not ARF3) facilitate BIG1 and BIG2 recruitment to the TGN. We localize GBF1 ultrastructurally to the pre-Golgi, the Golgi, and also the TGN. Our findings suggest a model in which GBF1 localized within pre-Golgi and Golgi compartments mediates ARF activation to facilitate recruitment of COPI to membranes, whereas GBF1 localized at the TGN mediates ARF activation that leads to the recruitment of BIG1 and BIG2 to the TGN. Membrane-associated BIG1/2 then activates ARFs that recruit clathrin adaptors. In this cascade, an early acting GEF (GBF1) activates ARFs that mediate recruitment of late acting GEFs (BIG1/2) to coordinate coating events within the pre-Golgi/Golgi/TGN continuum. Such coordination may optimize the efficiency and/or selectivity of cargo trafficking through the compartments of the secretory pathway.

Novel C-terminal motif within Sec7 domain of guanine nucleotide exchange factors regulates ADP-ribosylation factor (ARF) binding and activation

ADP-ribosylation factors (ARFs) and their activating guanine nucleotide exchange factors (GEFs) play key roles in membrane traffic and signaling. All ARF GEFs share a ∼200-residue Sec7 domain (Sec7d) that alone catalyzes the GDP to GTP exchange that activates ARF. We determined the crystal structure of human BIG2 Sec7d. A C-terminal loop immediately following helix J (loop>J) was predicted to form contacts with helix H and the switch I region of the cognate ARF, suggesting that loop>J may participate in the catalytic reaction. Indeed, we identified multiple alanine substitutions within loop>J of the full length and/or Sec7d of two large brefeldin A-sensitive GEFs (GBF1 and BIG2) and one small brefeldin A-resistant GEF (ARNO) that abrogated binding of ARF and a single alanine substitution that allowed ARF binding but inhibited GDP to GTP exchange. Loop>J sequences are highly conserved, suggesting that loop>J plays a crucial role in the catalytic activity of all ARF GEFs. Using GEF mutants unable to bind ARF, we showed that GEFs associate with membranes independently of ARF and catalyze ARF activation in vivo only when membrane-associated. Our structural, cell biological, and biochemical findings identify loop>J as a key regulatory motif essential for ARF binding and GDP to GTP exchange by GEFs and provide evidence for the requirement of membrane association during GEF activity.

Impact of reduction in working hours for doctors in training on postgraduate medical education and patients' outcomes: systematic review

OBJECTIVES

To determine whether a reduction in working hours of doctors in postgraduate medical training has had an effect on objective measures of medical education and clinical outcome.

DESIGN

Systematic review.

DATA SOURCES

Medline, Embase, ISI Web of Science, Google Scholar, ERIC, and SIGLE were searched without language restriction for articles published between 1990 and December 2010. Reference lists and citations of selected articles.

STUDY SELECTION

Studies that assessed the impact of a change in duty hours using any objective measure of outcome related to postgraduate medical training, patient safety, or clinical outcome. Any study design was eligible for inclusion.

RESULTS

72 studies were eligible for inclusion: 38 reporting training outcomes, 31 reporting outcomes in patients, and three reporting both. A reduction in working hours from greater than 80 hours a week (in accordance with US recommendations) does not seem to have adversely affected patient safety and has had limited effect on postgraduate training. Reports on the impact of European legislation limiting working hours to less than 56 or 48 a week are of poor quality and have conflicting results, meaning that firm conclusions cannot be made.

CONCLUSIONS

Reducing working hours to less than 80 a week has not adversely affected outcomes in patient or postgraduate training in the US. The impact of reducing hours to less than 56 or 48 a week in the UK has not yet been sufficiently evaluated in high quality studies. Further work is required, particularly in the European Union, using large multicentre evaluations of the impact of duty hours' legislation on objective educational and clinical outcomes.

Sonographic assisted diagnosis and treatment of bilateral gastrocnemius tendon rupture in a Labrador retriever repaired with fascia lata and polypropylene mesh

This case report describes a four-year-old, eighty-five pound, male neutered Labrador retriever that was admitted with unilateral lameness and clinical findings consistent with a unilateral gostrocnemius tendon rupture. A prior history of trauma was not identified. Ultrasonagraphic evaluation revealed bilateral gastrocnemius tendon defects in which approximately 80% of the tendon was ruptured on the clinically normal side, yet mechanical function and anatomical length were not apparently altered. Bilateral surgical repair was performed utilizing primary tendon reconstruction, supported by fascia lata, autograft and polypropylene mesh. The repairs were protected with rigid costs for two weeks following surgery, and replaced with orthotics through the complete recovery period. Orthotics provided semi-rigid support and allowed removal for controlled intermittent physical therapy. This surgical repair technique, combined with orthotic support, allowed for early mobilization and good ultimate outcome for a complicated bilateral condition.

The health burden of breast hypertrophy

Women seeking consultation for the surgical relief of symptoms associated with breast hypertrophy have been the focus of many studies. In contrast, little is known about those women with breast hypertrophy who do not seek symptomatic relief. The purpose of this study was to describe the health burden of breast hypertrophy by using a set of validated questionnaires and to compare women with breast hypertrophy who seek surgical treatment with those who do not. In addition, this latter group was compared with a group of control women without breast hypertrophy. Women seeking consultation for surgery were recruited from 14 plastic-surgery practices. Control subjects were recruited by advertisements in primary-care offices and newspapers. Women were asked to complete a self-report questionnaire that included the European Quality of Life (EuroQol) questionnaire, McGill Pain Questionnaire, Multidimensional Body Self Relations Questionnaire (MBSRQ), the Short Form-36 (SF-36) questionnaire, and questions regarding breast-related symptoms, comorbidities, and bra size. Descriptive statistics were compiled for three groups of women: (1) hypertrophy patients seeking surgical care, (2) hypertrophy control subjects (those whose reported bra-cup size was a D or larger), and (3) normal control subjects (those whose reported bra-cup size was an A, B, or C). The multiple linear regression method was used to compare the health burdens across groups while adjusting for other variables. Two hundred ninety-one women seeking surgical care and 195 control subjects were enrolled in the study. The 184 control subjects with bra-cup information available were further separated into 88 hypertrophy control subjects and 96 normal control subjects. In the control group, bra-cup size was correlated with health-burden measures, whereas in the surgical candidates, it was not. When scores were compared across the three groups, significant differences were found in all health-burden measures. The surgical candidates scored more poorly on the EuroQol utility, McGill pain rating index, MBSRQ appearance evaluation, physical component scale of the SF-36, and on breast symptoms than did the two control groups. In addition, the hypertrophy control subjects scored more poorly than the normal control subjects. With multiple linear regression analysis incorporating important potential confounders, the poorer scores in the surgical candidates remained statistically significant. It was concluded that breast hypertrophy in those seeking surgical care and those not seeking surgery has a significant impact on women's quality of life as measured by validated and widely used self-report instruments including the EuroQol, MBSRQ, McGill Pain Questionnaire, and the SF-36. Likewise, a new assessment instrument for breast-related symptoms also demonstrated greater symptomatology in women with breast hypertrophy.

Treatment of spider veins with the 595 nm pulsed-dye laser

BACKGROUND

Previous attempts to treat spider veins with the conventional 585 nm pulsed-dye laser with a 0.5-ms pulse duration have been relatively ineffective. Recently, a new pulsed-dye laser that is tunable from 585 to 600 nm with a pulse duration 3 times longer than previously available lasers has preliminarily been shown to be effective for treatment of spider veins.

OBJECTIVE

Our purpose was to evaluate the effectiveness of multiple treatments with the tunable long-pulse dye laser in treatment of spider veins of the lower extremity.

METHODS

Ten female volunteers were treated in two separate areas containing blue or red linear spider veins less than 1.5 mm in diameter. Treatments were administered with the pulsed-dye laser with a 1.5-ms pulse duration and 595-nm light at fluences of 15 and 20 J/cm2, and each subject received a total of 3 treatments at each site, administered at 6-week intervals. Photographs were taken before and 6 weeks after the last treatment.

RESULTS

Computer-based image analysis showed clearing of more than three fourths of veins after 3 treatments with 15 or 20 J/cm2. Side effects were minimal and the treatments were well tolerated.

CONCLUSION

The 595 nm, 1.5 ms pulse duration, pulsed-dye laser is safe and effective for treating blue or red spider veins of the lower extremities less than 1.5 mm in diameter in nontanned patients with Fitzpatrick skin types I and II. Multiple treatments improve on the results obtained after a single treatment.

Use of the therapeutic footwear benefit among diabetic medicare beneficiaries in three states, 1995

OBJECTIVE

To determine the extent to which Medicare provided reimbursement for therapeutic footwear to diabetic Medicare beneficiaries in Washington, Alaska, and Idaho in 1995.

RESEARCH DESIGN AND METHODS

Using inpatient, outpatient, and durable medical equipment claims data, we selected a cohort of diabetic Medicare beneficiaries. Therapeutic footwear claims were identified using a set of billing codes intended only for the diabetes footwear benefit. People at "high risk" or "possibly increased risk" for foot problems who might benefit from therapeutic footwear were identified using a combination of International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) diagnostic codes in any of the databases.

RESULTS

Among 608,804 beneficiaries, 10.2% (62,170) met the inclusion criteria for diabetes. Of the diabetic beneficiaries, 13.0% (8,079) had at least one "high risk" diagnosis, and 14.0% (8,686) had at least one "possibly increased risk" diagnosis. The percentage of diabetic beneficiaries with therapeutic footwear claims was 2.9% among those with diagnoses high risk, 0.7% among those with diagnoses indicating possibly increased risk, and 0.1% among those with no diagnosis from the list. Altogether, only 0.6% of beneficiaries meeting the diabetes case ascertainment criteria had a therapeutic footwear claim in 1995.

CONCLUSIONS

Few diabetic Medicare beneficiaries in Washington, Alaska, and Idaho had claims for reimbursement for therapeutic footwear in 1995. The low utilization of the footwear benefit may represent an important opportunity to improve care for Medicare beneficiaries with diabetes. Further work should be done to characterize the use of the benefit in other regions and to assess whether the low level of usage reflects underutilization.

Alteration of phosphoinositide metabolism, protein phosphorylation, and carbohydrate levels in sciatic nerve from Wistar fatty diabetic rats

Sciatic nerve from the Wistar fatty diabetic (FD) rat, a prospective model for non-insulin-dependent diabetes mellitus, was investigated to determine the content of carbohydrates and to measure the incorporation of 32P into phosphoinositides and proteins. This strain has been shown to develop structural abnormalities in nerves and to exhibit reduced conduction velocity. Males became diabetic between the ages of 8 and 10 wk and were maintained together with lean sibling controls until the animals were either 22 or 44 wk old. Throughout this period, FD rats displayed moderate hyperglycemia. The carbohydrate profile of FD rat sciatic nerve exhibited modest increases in glucose, fructose, and sorbitol levels and significantly reduced myo-inositol concentrations, which were comparable at both ages. When nerves from 22-wk-old animals were incubated with [32P]orthophosphate and incorporation of radioactivity into phospholipids was measured, an increase in isotope uptake into phosphatidylinositol-4,5-bisphosphate and phosphatidylinositol-4-phosphate in the distal portions of tissue from the FD rat was observed. This effect was more pronounced in nerves from 44-wk-old rats. Phosphorylation of the major myelin protein P0 was 70% higher in the most distal portion of FD sciatic nerve from 22-wk-old animals. A comparable rise in phosphorylation of P0 as well as the large (P1) and small (Pr) myelin basic proteins occurred in nerves from 44-wk-old rats. In these animals, an approximately 50% decrease in the uptake of 32P into P0 and P1 in the most proximal region of FD nerve was also apparent.(ABSTRACT TRUNCATED AT 250 WORDS)

Distribution of elements in rat peripheral axons and nerve cell bodies determined by x-ray microprobe analysis

X-ray microprobe analysis was used to determine concentrations (millimoles of element per kilogram dry weight) of Na, P, Cl, K, and Ca in cellular compartments of frozen, unfixed sections of rat sciatic and tibial nerves and dorsal root ganglion (DRG). Five compartments were examined in peripheral nerve (axoplasm, mitochondria, myelin, extraaxonal space, and Schwann cell cytoplasm), and four were analyzed in DRG nerve cell bodies (cytoplasm, mitochondria, nucleus, and nucleolus). Each morphological compartment exhibited characteristic concentrations of elements. The extraaxonal space contained high concentrations of Na, Cl, and Ca, whereas intraaxonal compartments exhibited lower concentrations of these elements but relatively high K contents. Nerve axoplasm and axonal mitochondria had similar elemental profiles, and both compartments displayed proximodistal gradients of decreasing levels of K, Cl, and, to some extent, Na. Myelin had a selectively high P concentration with low levels of other elements. The elemental concentrations of Schwann cell cytoplasm and DRG were similar, but both were different from that of axoplasm, in that K and Cl were markedly lower whereas P was higher. DRG cell nuclei contained substantially higher K levels than cytoplasm. The subcellular distribution of elements was clearly shown by color-coded images generated by computer-directed digital x-ray imaging. The results of this study demonstrate characteristic elemental distributions for each anatomical compartment, which doubtless reflect nerve cell structure and function.

Regulatory effects of S-100 protein and parvalbumin on protein kinases and phosphoprotein phosphatases from brain and skeletal muscle

In the eluted fractions of histone-treated crude extracts separated by Sephadex G-200 filtration, multiple protein kinase (PK) activities, including three from brain and two from skeletal muscle, were augmented by both S-100 protein and parvalbumin on the phosphorylation of endogenous substrates. One additional PK activity suppressed by both S-100 and parvalbumin was also found in muscle. In comparison, phosphoprotein phosphatases (PPase), which were also prepared by the same procedure of initial step of histone-treatment followed by the steps of Bio-Gel P-6DG for brain and DNA-cellulose for muscle, were all activated by S-100 while inhibited by parvalbumin and phosphatidylserine.