Emerging 'super ACOs' fill unique needs

Hospitals and health systems exploring the idea of forming or joining a "Super ACO" should consider several key factors: Pace of change and partnership opportunities in their market. Market concentration and the organization's size relative to larger competitors. Whether the organization is financially strong enough to participate. How prepared the organization is for accountable care and population management. Whether the organization is equipped to care for new patient populations.

The molecular basis of intervertebral disc degeneration

BACKGROUND

Intervertebral disc (IVD) degeneration remains a clinically important condition for which treatment is costly and relatively ineffective. The molecular basis of degenerative disc disease has been an intense focus of research recently, which has greatly increased our understanding of the biology underlying this process.

PURPOSE

To review the current understanding of the molecular basis of disc degeneration.

STUDY DESIGN

Review article.

METHODS

A literature review was performed to identify recent investigations and current knowledge regarding the molecular basis of IVD degeneration.

RESULTS

The unique structural requirements and biochemical properties of the disc contribute to its propensity toward degeneration. Mounting evidence suggests that genetic factors account for up to 75% of individual susceptibility to IVD degeneration, far more than the environmental factors such as occupational exposure or smoking that were previously suspected to figure prominently in this process. Decreased extracellular matrix production, increased production of degradative enzymes, and increased expression of inflammatory cytokines contribute to the loss of structural integrity and accelerate IVD degeneration. Neurovascular ingrowth occurs, in part, because of the changing degenerative phenotype.

CONCLUSIONS

A detailed understanding of the biology of IVD degeneration is essential to the design of therapeutic solutions to treat degenerative discs. Although significant advances have been made in explaining the biologic mediators of disc degeneration, the inhospitable biochemical environment of the IVD remains a challenging environment for biological therapies.

Cost-utility analysis in spine care: a systematic review

BACKGROUND CONTEXT

Despite the importance of the information provided by cost-utility analyses (CUAs), there has been a lack of these types of studies performed in the area of spinal care.

PURPOSE

To systematically review cost-utility studies published on spinal care between 1976 and 2010.

STUDY DESIGN

Systematic review.

METHODS

All CUAs pertaining to spinal care published between 1976 and 2010 were identified using the cost-effectiveness analysis (CEA) registry database (Tufts Medical Center, Institute for Clinical Research and Health Policy) and National Health Service Economic Evaluation Database (NHS EED). The keywords used to search both the registry databases were the following: spine, spinal, neck, back, cervical, lumbar, thoracic, and scoliosis. Search of the CEA registry provided a total of 28 articles, and the NHS EED yielded an additional 5, all of which were included in this review. Each article was reviewed for the study subject, methodology, and results. Data contained within the databases for each of the 33 articles were recorded, and the manuscripts were reviewed to provide insight into the funding source, analysis perspective, discount rate, and cost-utility ratios.

RESULTS

There was wide variation among the 33 studies in methodology. There were 17 operative, 13 nonoperative, and 3 imaging studies. Study subjects included lumbar spine (n=27), cervical spine (n=4), scoliosis (n=1), and lumbar and cervical spine (n=1). Twenty-three of the studies were based on the clinical data from prospective randomized studies, 7 on decision models, 2 on prospective observational data, and 1 on a retrospective case series. Sixty cost-utility ratios were reported in the 33 articles. Of the ratios, 19 of 60 (31.6%) were cost saving, 27 of 60 (45%) were less than $100,000/quality-adjusted life year (QALY) gain, and 14 of 60 (23.3%) were greater than $100,000/QALY gain. Only four of 33 (12%) studies contained the four key criteria of cost-effectiveness research recommended by the US Panel on Cost-Effectiveness in Health and Medicine.

CONCLUSIONS

Thirty-three CUA studies and 60 cost-utility ratios have been published on various aspects of spinal care over the last 30 years. Certain aspects of spinal care have been shown to be cost effective. Further efforts, however, are needed to better define the value of many aspects of spinal care. Future CUA studies should consider societal cost perspective and carefully consider the durability of clinical benefit in determining a study time horizon.

Dysphagia and soft-tissue swelling after anterior cervical surgery: a radiographic analysis

BACKGROUND CONTEXT

Dysphagia is common in the early postoperative period after anterior cervical discectomy and fusion (ACDF). Several mechanisms, including soft-tissue swelling, have been implicated as a cause of postoperative dysphagia.

PURPOSE

To determine whether anterior soft-tissue swelling is greater in patients with postoperative dysphagia.

STUDY DESIGN

Prospective cohort study.

PATIENT SAMPLE

Forty-three patients.

OUTCOME MEASURES

Validated dysphagia questionnaire, lateral cervical spine radiographs.

METHODS

Patients undergoing one- or two-level ACDF using allograft bone and anterior instrumentation were enrolled. Baseline patient demographic characteristics and history were recorded. A dysphagia questionnaire, including a dysphagia numeric rating scale (DNRS; range, 0-10), was administered preoperatively and 2 and 6 weeks postoperatively. Lateral cervical radiographs were obtained preoperatively and 2 and 6 weeks postoperatively. The anterior cervical soft-tissue shadow width was measured at each level. Patients were divided into groups based on the 2-week dysphagia questionnaire: Group 1 (no symptoms/mild dysphagia) and Group 2 (moderate/severe dysphagia). Anterior soft-tissue shadow width at each level was compared between groups. Correlation was used to assess the relationship between DNRS and anterior soft-tissue swelling.

RESULTS

Forty-three patients (24 females; average age, 47.9) were enrolled. Fifteen patients had one-level and 28 patients had two-level ACDF. The anterior soft-tissue shadow width increased significantly from preoperative values at all levels except C1 at 2 and 6 weeks and C2 at 6 weeks. At 2 weeks, 18 patients had no symptoms/mild dysphagia (Group 1) and 25 patients had moderate/severe dysphagia (Group 2). The average DNRS was 1.1 for Group 1 and 5.3 for Group 2 (p<.001). This difference decreased by 6 weeks but remained significant. There were no significant differences in the soft-tissue measurements between groups at any level. There was no significant correlation between the DNRS and anterior soft-tissue swelling at any time point.

CONCLUSIONS

There is a significant increase in anterior cervical soft-tissue swelling after ACDF. The width of prevertebral soft-tissue does not correlate with postoperative dysphagia.

Minimally invasive surgery for the lumbar spine

Minimally invasive spine surgery is a rapidly developing field that has the potential to decrease surgical morbidity and improve recovery compared to traditional spinal approaches. Minimally invasive approaches have been developed for all regions of the spine, but have been best documented for degenerative conditions of the lumbar spine. Lumbar decompression and lumbar interbody fusion are two of the most well-studied minimally invasive surgical approaches. This article will review both the rationale and technique for minimally invasive lumbar decompression and for a minimally invasive transforaminal lumbar interbody fusion (TLIF).

Oxidation of 3,4-dihydroxyphenylacetaldehyde, a toxic dopaminergic metabolite, to a semiquinone radical and an ortho-quinone

The oxidation and toxicity of dopamine is believed to contribute to the selective neurodegeneration associated with Parkinson disease. The formation of reactive radicals and quinones greatly contributes to dopaminergic toxicity through a variety of mechanisms. The physiological metabolism of dopamine to 3,4-dihydroxyphenylacetaldehyde (DOPAL) via monoamine oxidase significantly increases its toxicity. To more adequately explain this enhanced toxicity, we hypothesized that DOPAL is capable of forming radical and quinone species upon oxidation. Here, two unique oxidation products of DOPAL are identified. Several different oxidation methods gave rise to a transient DOPAL semiquinone radical, which was characterized by electron paramagnetic resonance spectroscopy. NMR identified the second oxidation product of DOPAL as the ortho-quinone. Also, carbonyl hydration of DOPAL in aqueous media was evident via NMR. Interestingly, the DOPAL quinone exists exclusively in the hydrated form. Furthermore, the enzymatic and chemical oxidation of DOPAL greatly enhance protein cross-linking, whereas auto-oxidation results in the production of superoxide. Also, DOPAL was shown to be susceptible to oxidation by cyclooxygenase-2 (COX-2). The involvement of this physiologically relevant enzyme in both oxidative stress and Parkinson disease underscores the potential importance of DOPAL in the pathogenesis of this condition.

Dopamine-derived biological reactive intermediates and protein modifications: Implications for Parkinson's disease

Dopamine (DA) undergoes monoamine oxidase catalyzed oxidative deamination to 3,4-dihydroxyphenylacetaldehyde (DOPAL), which is metabolized primarily to 3,4-dihydroxyphenylacetic acid (DOPAC) via aldehyde dehydrogenase (ALDH). Previous studies demonstrated DOPAL to be neurotoxic, more so than DA and other metabolites, and implicated the aldehyde intermediate as a factor in the pathogenesis of Parkinson's disease (PD). However, the mechanism for generation of DOPAL at aberrant levels and the pathways for toxicity are not conclusively known. Various models for DA catabolism revealed the susceptibility of DOPAL biotransformation (e.g., ALDH) to products of oxidative stress, e.g., 4-hydroxy-2-nonenal, at physiologic/pathologic levels and agents that induce oxidative stress. An elevated concentration of DOPAL correlated with increased protein modification with subsequent work demonstrating significant reactivity of the DA-derived electrophile toward protein nucleophiles compared to DA and other metabolites, e.g., DOPAC. The addition of DOPAL to proteins proceeds via reaction of the aldehyde with Lys residues, yielding a Schiff base; however, post-adduction chemistry occurs for the DOPAL-modification resulting in protein cross-linking. Preliminary work indicates enzymes in DA synthesis and catabolism to be cellular targets for DOPAL. Functional consequences for elevated levels of the DA-derived aldehyde and protein modification may include adverse cellular effects. These data implicate DOPAL as a toxic and reactive intermediate potentially serving as a "chemical trigger" for some stage of PD pathogenesis.

In Vivo Cloning of lac Genes in Streptococcus lactis ML3

The isolation and characterization of a Streptococcus lactis ML3 strain which possessed a recombinant lactose plasmid is described. The recombination events generating this plasmid occurred in vivo in a recombination-deficient strain and appeared to be mediated by transposition events. Restriction mapping revealed that the recombinant plasmid, pDA0307, contained a region of the lactose plasmid, pSK08, linked to another resident plasmid, pSK07. Copy number determinations indicated that the lac genes were present at approximately 20 copies per cell in pDA0307, whereas the lac genes are normally present at approximately 10 copies per cell in pSK08. The strain containing pDA0307 displayed a 21 to 54% increase in the expression of the Lac enzyme phospho-beta-d-galactosidase. However, the strain containing pDA0307 both grew and produced lactic acid in milk at rates identical to that of a strain containing pSK08. This result suggests that lac gene dosage of plasmid-linked lac genes was not limiting the rate at which these derivatives of S. lactis ML3 fermented milk.

Lipid-based nanotherapeutics for siRNA delivery

RNA interference (RNAi) is a specific gene-silencing mechanism triggered by small interfering RNA (siRNA). The application of RNAi in the clinic requires the development of safe and effective delivery systems. Inspired by progress with lipid-based systems in drug delivery, efforts have been dedicated to the development of liposomal siRNA delivery systems. Many of the lipid-based delivery vehicles self-assemble with siRNA through electrostatic interactions with charged amines, generating multi-lamellar lipoplexes with positively charged lipid bilayers separated from one another by sheets of negatively charged siRNA strands. Internalization of lipid-based siRNA delivery systems into cells typically occurs through endocytosis; accordingly, delivery requires materials that can facilitate endosomal escape. The size of the carrier is important as carriers <100 nm in diameter have been reported to have higher accumulation levels in tumours, hepatocytes and inflamed tissue, whereas larger particles tend to be taken up by Kupffer cells or other components of the reticuloendothelial system (RES). To reduce RES uptake and increase circulation time, carriers have been modified on the surface with hydrophilic materials, such as polyethyleneglycol. Herein, we review the molecular and structural parameters of lipid-based siRNA delivery systems.

Complications associated with single-level transforaminal lumbar interbody fusion

BACKGROUND CONTEXT

The transforaminal lumbar interbody fusion (TLIF) procedure has become an increasingly popular means of obtaining a circumferential fusion while avoiding the morbidity of the anterior approach. Concerns remain, however, regarding the clinical efficacy and safety of its use.

PURPOSE

The purpose of this study was to evaluate the complications of the single-level TLIF procedure. The difference in complications observed with the use of iliac crest autograft compared with rhBMP-2 will be assessed.

STUDY DESIGN

Retrospective cohort study; a review of complications.

METHODS

Patients who underwent a single-level TLIF between January 2004 to May 2007 with either autograft iliac crest or rhBMP-2 were identified. A retrospective review of these patients included operative reports, pre- and postoperative medical records, most recent postoperative dynamic and static lumbar radiographs, and computed tomography scans (when available).

RESULTS

A total of 130 patients met the study criteria; 119 patients were available for follow-up, with an average radiographic follow-up of 19.1 months and an average clinical follow-up of 27.6 months. Thirty-three patients received iliac crest autograft and 86 patients received rhBMP-2. Complications occurred in 40 of the 119 study patients (33.6%). The autograft group had a higher complication rate (45.5% vs. 29.1%), but the difference was not statistically significant (p=.09). Complications in the autograft group included persistent donor-site pain (30.3%), donor-site infection (3.1%), lumbar wound infection (6.1%), and postoperative radiculitis (3.0%). Complications in the rhBMP-2 group included postoperative radiculitis (14.0%), vertebral osteolysis (5.8%), ectopic bone formation (2.3%), and lumbar wound infection (3.5%). A hydrogel sealant (Duraseal; Confluent Surgical Inc., Waltham, MA, USA) was used in 37 out of 86 patients in the rhBMP-2 group. The use of this sealant decreased the rate of postoperative radiculitis in the rhBMP-2 group from 20.4% to 5.4% (p=.047). The radiographic nonunion rate at most recent follow-up was 3.0% in the autograft group and 3.5% (p=.90) in the rhBMP-2 group.

CONCLUSIONS

The most common complications in the autograft group were related to the donor site. The most common complication in the rhBMP-2 group was postoperative radiculitis, the incidence of which is reduced by the use of a hydrogel sealant.

Products of oxidative stress inhibit aldehyde oxidation and reduction pathways in dopamine catabolism yielding elevated levels of a reactive intermediate

Dopamine (DA) has been implicated as an endogenous neurotoxin to explain the selective neurodegeneration as observed for Parkinson's disease (PD). In addition, oxidative stress and lipid peroxidation are hypothesized culprits in PD pathogenesis. DA undergoes catabolism by monoamine oxidase (MAO) to 3,4-dihydroxyphenylacetaldehyde (DOPAL), which is further oxidized to 3,4-dihydroxyphenylacetic acid (DOPAC) via aldehyde dehydrogenase (ALDH). As a minor and compensatory metabolic pathway, DOPAL can be reduced to 3,4-dihydroxyphenylethanol (DOPET) via cytosolic aldehyde or aldose reductase (AR). Previous studies have found DOPAL to be significantly more toxic to DA cells than DA and that the major lipid peroxidation products, that is, 4-hydroxynonenal (4HNE) and malondialdehyde (MDA), potently inhibit DOPAL oxidation via ALDH. The hypothesis of this work is that lipid peroxidation products inhibit DOPAL oxidation, yielding aberrant levels of the toxic aldehyde intermediate. To test this hypothesis, nerve growth factor-differentiated PC6-3 cells were used as a model for DA neurons. Cell viability in the presence of 4HNE and MDA (2-100 microM) was measured by MTT assay, and it was found that only 100 microM 4HNE exhibited significant cytotoxicity. Treatment of cells with varying concentrations of 4HNE and MDA resulted in reduced DOPAC production and significant elevation of DOPAL levels, suggesting inhibition of ALDH. In cells treated with 4HNE that exhibited elevated DOPAL, there was a significant increase in DOPET. However, elevated DOPET was not observed for the cells treated with MDA, suggesting MDA to be an inhibitor of AR. Using isolated cytosolic AR, it was found that MDA but not 4HNE inhibited reductase activity toward DOPAL, surprisingly. These data demonstrate that the oxidative stress products 4HNE and MDA inhibit the aldehyde biotransformation step of DA catabolism yielding elevated levels of the endogenous neurotoxin DOPAL, which may link oxidative stress to selective neurodegeneration as seen in PD.

Lipid Peroxidation Products Inhibit Dopamine Catabolism Yielding Aberrant Levels of a Reactive Intermediate

Recent work indicates that oxidative stress is a factor in Parkinson's disease (PD); however, it is unknown how this condition causes selective dopaminergic cell death. The neurotransmitter dopamine (DA) has been implicated as an endogenous neurotoxin to explain the selective neurodegeneration. DA undergoes catabolism by monoamine oxidase (MAO) to the reactive intermediate 3,4-dihydroxyphenylacetaldehyde (DOPAL), which is further oxidized to 3,4-dihydroxyphenylacetic (DOPAC) acid via mitochondrial aldehyde dehydrogenase (ALDH). Previous studies found DOPAL to be more toxic than DA, and the major lipid peroxidation products, that is, 4-hydroxynonenal (4HNE) and malondialdehyde (MDA), potently inhibit ALDH. The hypothesis of this work is that lipid peroxidation products inhibit DOPAL oxidation, yielding aberrant levels of the reactive aldehyde intermediate. Treatment of striatal synaptosomes with 2-100 microM 4HNE or 2-50 microM MDA impaired DOPAL oxidation, resulting in elevated [DOPAL]. The aberrant concentration of DOPAL yielded an increase in protein modification by the DA-derived aldehyde, evident via staining of proteins with nitroblue tetrazolium (NBT). Pretreatment of synaptosomes with an MAO inhibitor significantly decreased NBT staining. On the basis of NBT staining, the order of protein reactivity for DA and metabolites was found to be DOPAL>>DOPAC>DA. Mass spectrometric analysis of a model peptide reacted with DOPAL revealed the adduct to be a Schiff base product. In summary, these data demonstrate the sensitivity of DA catabolism to the lipid peroxidation products 4HNE and MDA even at low, physiologic levels and suggest a mechanistic link between oxidative stress and generation of aberrant levels of an endogenous and protein reactive dopaminergic toxin relevant to PD.

Comment on "Redefining the Age of Clovis: Implications for the Peopling of the Americas"

Waters and Stafford (Reports, 23 February 2007, p. 1122) provided useful information about the age of some Clovis sites but have not definitively established the temporal span of this cultural complex in the Americas. Only a continuing program of radiometric dating and careful stratigraphic correlations can address the lingering ambiguity about the emergence and spread of Clovis culture.

Is Siberian Reindeer Herding in Crisis? Living with Reindeer Fifteen Years After the End of State Socialism

Most commentators on Siberian reindeer herding conclude that the dramatic drop in the numbers of domestic reindeer after the collapse of state socialism point to a crisis in reindeer husbandry. This article argues that instead of focusing on numbers we should focus on the way people form new relationships with reindeer in order to take advantage of opportunities thrown up by the post-Soviet landscape. By making reference to two case studies in the taiga and tree line areas, the author gives examples of 'interstitial practices' that reindeer herders use to survive and profit from fractured and over-regulated spaces. The author argues that the unique skills of reindeer herding, which allow people to alter the way that they use space and react to temporal pressures, give post-Soviet reindeer herders a unique adaptive strategy in a post-Soviet economy.

Inhibition of the oxidative metabolism of 3,4-dihydroxyphenylacetaldehyde, a reactive intermediate of dopamine metabolism, by 4-hydroxy-2-nonenal

Recent evidence indicates a role for oxidative stress and resulting products, e.g. 4-hydroxy-2-nonenal (4HNE) in the pathogenesis of Parkinson's disease (PD). 4HNE is a known inhibitor of mitochondrial aldehyde dehydrogenase (ALDH2), an enzyme very important to the dopamine (DA) metabolic pathway. DA undergoes monoamine oxidase-catalyzed oxidative deamination to 3,4-dihydroxyphenylacetaldehyde (DOPAL), which is metabolized primarily to 3,4-dihydroxyphenylacetic acid (DOPAC) via ALDH2. The biotransformation of DOPAL is critical as previous studies have demonstrated this DA-derived aldehyde to be a reactive electrophile and toxic to dopaminergic cells. Therefore, 4HNE produced via oxidative stress may inhibit ALDH2-mediated oxidation of the endogenous neurotoxin DOPAL. To test this hypothesis, ALDH2 in various model systems was treated with 4HNE and activity toward DOPAL measured. Incubation of human recombinant ALDH2 with 4HNE (1.5-30 microM) yielded inhibition of activity toward DOPAL. Furthermore, ALDH2 in rat brain mitochondrial lysate as well as isolated rat brain mitochondria was also sensitive to the lipid peroxidation product at low micromolar, as evident by a decrease in the rate of DOPAL to DOPAC conversion measured using HPLC. Taken together, these data indicate that 4HNE at low micromolar inhibits mitochondrial biotransformation of DOPAL to DOPAC, and generation of the lipid peroxidation product may represent a mechanism yielding aberrant levels of DOPAL, thus linking oxidative stress to the uncontrolled production of an endogenous neurotoxin relevant to PD.

Internet patient care applications in ambulatory care

Over the next decade, the Internet and related technologies will revolutionize the administrative and clinical practices of ambulatory care, enhancing the ability of physicians to provide quality care, enabling "virtual care teams" to help patients deal effectively with acute episodes and chronic conditions, and reducing the cost of care. Like any major paradigm shift, this change will not happen overnight. Nor will it be without cost. The explosion of venture capital and meteoric rise of the Nasdaq in 1999 reflected the promise of the Internet to revolutionize many aspects of American business. The Nasdaq's equally rapid descent in 2000 reflected a growing realization that this change will not be free--that "creative destruction," to use Schumpeter's term, will inevitably require significant investment and produce substantial losses. This article takes a longer term view than the ups and downs in the stock market. We believe the forces unleashed by the Internet are inexorable and that 10 years from now we will look back at the millennium's first decade as a period when the practice of ambulatory medicine was transformed by communication technology.

Noncontact dipole effects on channel permeation. V. Computed potentials for fluorinated gramicidin

Experimental and theoretical calculations indicate that the dipole moment of the four Trp side chains in gramicidin A (gA) channels modify channel conductance through long-range electrostatic interactions. Electrostatic ion/side-chain interaction energies along the channel were computed with CHARMM using ab initio atom charges for native and 4-, 5-, or 6-fluorinated Trp side chains. The bulk water reaction to the polar side chains was included using the method of images as implemented by, and channel waters in idealized structures were included. Ion/Trp interaction energies were approximately -0.6 kcal/mol throughout the channel for all four of the native Trp pairs. Channel waters produced a modest reduction in the magnitude of interactions, essentially offsetting images representing the bulk water outside the channel. The effects of side-chain fluorination depended on ring position and, to a lesser extent, residue number. Compared with native Trp, 5-fluorination reduces the translocation barrier with minor effects on the exit barrier. In contrast, 6-fluorination primarily reduces exit barrier. 4-Fluorination produces a more complex double-well energy profile. Effects of measured side-chain movements resulting from fluorination or change in lipid bilayer were negligible whereas thermal side chain librations cause large effects, especially in the region of the ion-binding sites.

Paleoindian interaction and mating networks: reply to Moore and Moseley

How early human populations in North America maintained reproductive viability is a question that has shaped our research for over a decade. The concept of staging areas, mechanisms for band-macroband interaction, and an examination of how interaction networks could have formed and evolved over the course of the Paleoindian era are all solutions that we have presented.

Families of origin of homeless and never-homeless women

Naturalistic inquiry was used to compare the characteristics of families of origin of homeless women with never-homeless women. The women's experiences in their families of origin were explored during in-depth interviews using Lofland and Lofland's conceptions of meanings, practices, episodes, roles, and relationships to guide the analysis. The two groups were similar with respect to family abuse history, transience, and loss. The never-homeless women had support from an extended family member who provided unconditional love, protection, a sense of connection, and age-appropriate expectations, as contrasted with homeless women who described themselves as being without, disconnected, and having to be little adults in their families of origin. The experience of family love and connection seemed to protect never-homeless women from the effects of traumatic life events in childhood. These findings provide support for the influence of a woman's family of origin as a precursor to homelessness.

Coping strategies and burnout among veteran child protection workers

OBJECTIVES

First, to learn how veteran (2 years or more) child protective service (CPS) investigations workers cope with job stress; and secondly, to examine the relationship between coping strategies and levels of emotional exhaustion, depersonalization, and sense of reduced personal accomplishment (burnout syndrome).

METHOD

Cross-sectional, self-report methodology was used to measure coping strategies and the burnout syndrome. The voluntary subjects were 151 front-line CPS workers with at least 2 years experience in a southeastern Department of Social Services. They attended one of nine stress management workshops provided in various locations around the state. Quantitative analyses were run on the data.

RESULTS

These workers perceived themselves to use Engaged (active) coping strategies more than Disengaged (avoidant) strategies. Sixty-two percent of participants scored in the high range on Emotional Exhaustion, the aspect some researchers consider to be the heart of Burnout. Those who used Engaged coping were less likely to feel depersonalized and more likely to feel a sense of personal accomplishment. Those who used Disengaged coping were more likely to feel emotionally exhausted, depersonalized, and to have a sense of reduced personal accomplishment.

CONCLUSION

Neither the use of active nor avoidant coping strategies saved these workers from Emotional Exhaustion. The problem-focused strategies they are taught and use most do not help deal with the emotional content and context of their work, suggesting the use of emotion-focused coping to prevent and remediate burnout.

Rangifer and human interests

This article reviews biological and anthropological literatute on wild and tame Rangifer to demonstrate the powerful effect that this species has had on the imaginations of biologists, social scientists and local hunters. Through identifying a general 'human interest' in Rangifer, the author argues that there is great potential for these three communities to work together. To demonstrate this idea, the paper reviews several examples of successful and unsuccessful 'alliances' between local peoples and both natural and social scientists which have had a fundamental impact upon the history of these sciences. The paper examines recent theorerical models which suggest that human action is a major factor in the behaviour and ecology of the animals. The paper also analyses the ideas of many indigenous people for whom there is no categorical difference between semi-domesticated, semi-sedentary and migratory Rangifer through comparison with many 'anomalous' texts in English and Russian language wildlife biology. By reviewing the history of scholarly interest in Rangifer, the author argues that contemporary models of Rangifer behaviour and identity could be 'revitalised' and 'recalibrated' through the establishment of that dialogue between scientists and local peoples which so characterised the 19th century. Such a dialogue, it is argued, would help mediate many of the political conflicts now appearing in those districts where Rangifer migrate.

A single mutation, RecB(D1080A,) eliminates RecA protein loading but not Chi recognition by RecBCD enzyme

Homologous recombination and double-stranded DNA break repair in Escherichia coli are initiated by the multifunctional RecBCD enzyme. After binding to a double-stranded DNA end, the RecBCD enzyme unwinds and degrades the DNA processively. This processing is regulated by the recombination hot spot, Chi (chi: 5'-GCTGGTGG-3'), which induces a switch in the polarity of DNA degradation and activates RecBCD enzyme to coordinate the loading of the DNA strand exchange protein, RecA, onto the single-stranded DNA products of unwinding. Recently, a single mutation in RecB, Asp-1080 --> Ala, was shown to create an enzyme (RecB(D1080A)CD) that is a processive helicase but not a nuclease. Here we show that the RecB(D1080A)CD enzyme is also unable to coordinate the loading of the RecA protein, regardless of whether chi sites are present in the DNA. However, the RecB(D1080A)CD enzyme does respond to chi sites by inactivating in a chi-dependent manner. These data define a locus of the RecBCD enzyme that is essential not only for nuclease function but also for the coordination of RecA protein loading.

A clinical assessment of the effects of 10% carbamide peroxide gel on human pulp tissue

Bleaching vital teeth with 10% carbamide peroxide gel is a routine procedure in which there has been no evidence of associated permanent pulpal damage. Synthesis of the enzyme heme oxygenase-1 (HO-1) is increased after exposure of eukaryotic cells to conditions of oxidative stress (including H2O2) as a defense against the damaging effects of free radicals. Dental pulps were evaluated for HO-1 (aka Heat Shock Protein 32) presence in teeth treated with 10% carbamide peroxide. Seventeen intact first premolars scheduled for orthodontic extraction were bleached for 4 h immediately preceding extraction. Fourteen additional premolars from the same individuals were not bleached. All 31 teeth were extracted, fixed, demineralized, frozen, sectioned, and immunostained with anti-HO-1 antibody using a standard ABC protocol. There was no significant difference in the presence of HO-1 between total bleached versus total unbleached teeth using the Fisher's Exact Test (p < or = 0.05). However, the histological findings could be interpreted to suggest that coronal odontoblasts and endothelial cells in the underlying pulp proper may have the potential to respond to oxidative stress by increasing the synthesis of HO-1 (HSP32). This could represent a component of an initial defensive response by specific cells in strategic locations in the pulp that precedes classical inflammatory pathways.

The RecBC enzyme loads RecA protein onto ssDNA asymmetrically and independently of chi, resulting in constitutive recombination activation

Double-strand DNA break repair and homologous recombination in Escherichia coli proceed by the RecBCD pathway, which is regulated by cis-acting elements known as chi sites. A crucial feature of this regulation is the RecBCD enzyme-directed loading of RecA protein specifically onto the 3'-terminal, chi-containing DNA strand. Here we show that RecBC enzyme (lacking the RecD subunit) loads RecA protein constitutively onto the 3'-terminal DNA strand, with no requirement for chi. This strand is preferentially utilized in homologous pairing reactions. We propose that RecA protein loading is a latent property of the RecBCD holoenzyme, which is normally blocked by the RecD subunit and is revealed following interaction with chi.

Noncontact dipole effects on channel permeation. II. Trp conformations and dipole potentials in gramicidin A

The four Trp dipoles in the gramicidin A (gA) channel modulate channel conductance, and their side chain conformations should therefore be important, but the energies of different conformations are unknown. A conformational search for the right-handed helix based on molecular mechanics in vacuo yielded 46 conformations within 20 kcal/mol of the lowest energy conformation. The two lowest energy conformations correspond to the solid-state and solution-state NMR conformations, suggesting that interactions within the peptide determine the conformation. For representative conformations, the electrostatic potential of the Trp side chains on the channel axis was computed. A novel application of the image-series method of. Biophys. J. 9:1160-1170) was introduced to simulate the polarization of bulk water by the Trp side chains. For the experimentally observed structures, the CHARm toph19 potential energy (PE) of a cation in the channel center is -1.65 kcal/mol without images. With images, the PE is -1.9 kcal/mol, demonstrating that the images further enhance the direct dipole effect. Nonstandard conformations yielded less favorable PEs by 0.4-1.1 kcal/mol.

Reconstitution of an SOS response pathway: derepression of transcription in response to DNA breaks

E. coli responds to DNA damage by derepressing the transcription of about 20 genes that make up the SOS pathway. Genetic analyses have shown that SOS induction in response to double-stranded DNA (dsDNA) breaks requires LexA repressor, and the RecA and RecBCD enzymes--proteins best known for their role as initiators of dsDNA break repair and homologous recombination. Here we demonstrate that purified RecA protein, RecBCD enzyme, single-stranded DNA-binding (SSB) protein, and LexA repressor respond to dsDNA breaks in vitro by derepressing transcription from an SOS promoter. Interestingly, derepression is more rapid if the DNA containing the dsDNA break has a chi recombination hot spot (5'-GCTGGTGG-3'), suggesting a novel regulatory role for one of the most overrepresented octamers in the E. coli genome.