20-year Inflation-Adjusted Medicare Reimbursements (Years: 2000-2020) For Common Lumbar and Cervical Degenerative Disc Disease Procedures

OBJECTIVE

Reimbursement trends for common procedures have persistently declined over the past 2 decades. Spinal instrumentational and fusion procedures are increasingly utilized and have increased in clinical complexity, yet longitudinal inflation-adjusted data for Medicare reimbursements of these procedures have not been evaluated.

METHODS

The Centers for Medicare and Medicaid Services (CMS) Physician Fee Schedule Look-Up Tool was used to extract Medicare reimbursements for the 5 most common spinal procedures and associated instrumentations from 2000-2020. Current Procedural Terminology (CPT) codes include 22551, 22600, 22633, 63030, and 63047 as well as instrumentation CPT codes 22840 and 22842-6. The nominal values were adjusted for inflation according to the latest consumer price index (U.S. Bureau of Labor Statistics; reported as 2020 USD) and used to calculate average annual percent changes and compound annual growth rates (CAGRs) in reimbursements.

RESULTS

After inflation adjustment, the physician fee reimbursement decreased by 11.05% ± 8.46% (mean ± s.d., from $2,009.89 in 2011 to $1,787.85 in 2020) for anterior cervical discectomy and fusion (ACDF), 28.38% ± 8.42% (from $1,889.38 in 2000 to $1,353.14 in 2020) for posterior cervical fusion, 7.85% ± 8.20% (from $2,111.20 in 2012 to $1,945.49 in 2020) for transforaminal lumbar interbody fusion (TLIF), 28.17% ± 13.88% (from $1,421.78 in 2000 to $1,021.22 in 2020) for lower back disc surgery, and 31.88% ± 8.22% (from $1,700.38 in 2000 to $1,158.25 in 2020) for lumbar laminectomy. Instrumentation reimbursements showed an average decrease of 33.43% ± 8.4% over this period. Average CAGR was -1.7% ± .41% for procedures and -2.02% ± .14% for instrumentation.

CONCLUSION

Our analysis reveals a persistent decline in reimbursement rates of the most common spine procedures and instrumentation since the year 2000. If unaddressed, this trend can serve as a substantial disincentive for physicians to perform these procedures and can significantly limit access to spinal care at the population level.

Characterization of the influence of spinopelvic parameters on thoracolumbar trauma

OBJECTIVE

The current Roussouly classification identifies four groups of "normal" sagittal spine morphology, which has greatly expanded the understanding of normal heterogeneity of the spine. While there has been extensive characterization of the influence of spinopelvic parameters on outcomes after degenerative spine surgery, the influence of spinopelvic parameters on thoracolumbar trauma has yet to be described. The goal of this study was to determine if spinopelvic parameters and global spine morphology influence fracture location, fracture morphology, and rate of neurological deficit in the setting of thoracolumbar trauma.

METHODS

Of 2896 patients reviewed in the authors' institutional spine database between January 2014 and April 2020 with an ICD-9/10 diagnosis of thoracolumbar trauma, 514 met the inclusion criteria of acute thoracolumbar fracture on CT and visible femoral heads on sagittal CT. Pelvic incidence (PI) was calculated on sagittal CT. Demographic and clinical data including age, sex, BMI, smoking status, concomitant cervical fracture, mechanism of injury, major fracture location, neurological deficit, AO Spine thoracolumbar injury classification, and management type (operative vs nonoperative) were collected. Patients were stratified into high-PI (≥ 50°) and low-PI (< 50°) groups.

RESULTS

Patients with high PI had a lower incidence of fractures in the lower lumbar spine (below L2) compared with patients with low PI (16% vs 8%, p < 0.01). The last lordotic vertebrae were observed between T10 and L4, and of fractures that occurred at these levels, 75% were at the last lordotic vertebrae. Fall from height was the most common cause of neurological deficit, accounting for 47%. Of the patients presenting with a fall from height, AO Spine type B distraction injuries were more common in the high-PI group (41% vs 18%, p = 0.01). Similarly, within the same subgroup, AO Spine type A compression injuries were more common in the low-PI group (73% vs 53%, p = 0.01).

CONCLUSIONS

Spinopelvic parameters and sagittal balance influence the location and morphology of thoracolumbar fractures. Fractures of the thoracolumbar junction are strongly associated with the inflection point, which is defined by sagittal alignment. While the importance of considering sagittal balance is known for decision-making in degenerative spinal pathology, further studies are required to determine if spinopelvic parameters and sagittal balance should play a role in the decision-making for management of thoracolumbar fractures.

Detection of Ureaplasma diversum in the upper airways of Australian feedlot cattle

Bovine respiratory disease (BRD) exerts a major impact on the beef cattle industry nationally and worldwide, with a range of aetiological factors impacting its pathogenesis. Previous research has focussed on an increasing number of bacteria and viruses that have been shown to play a role in eliciting disease. Recently, additional agents have been emerging as potential contributors to BRD, including the opportunistic pathogen Ureaplasma diversum. To determine if U. diversum was present in Australian feedlot cattle and if that presence was linked to BRD, nasal swabs were collected from a cohort of 34 hospital pen animals and compared to 216 apparently healthy animals sampled contemporaneously at feedlot induction and again after 14 days on feed at an Australian feedlot. All samples were subjected to a de novo polymerase chain reaction (PCR) assay targeting U. diversum in combination with other BRD agents. U. diversum was detected at a low prevalence in cattle at induction (Day 0: 6.9%, Day 14: 9.7%), but in a significantly greater proportion of cattle sampled from the hospital pen (58.8%). When considering the presence of other BRD-associated agents, co-detection of U. diversum and Mycoplasma bovis was most common in hospital pen animals receiving treatment for BRD. These findings suggest that U. diversum may be an opportunistic pathogen involved in the aetiology of BRD in Australian feedlot cattle, in combination with other agents, with further studies are warranted to identify if a causal relationship exists.

Efficiency-corrected PCR quantification for identification of prevalence and load of respiratory disease-causing agents in feedlot cattle

Bovine respiratory disease (BRD) is the most prevalent disease in feedlot cattle worldwide with Bovine alphaherpesvirus 1 (BoAHV1), Histophilus somni, Mannheimia haemolytica, Mycoplasma bovis, Pasteurella multocida and Trueperella pyogenes accepted to be common etiological agents associated with BRD. Although these agents are common in the upper and lower airways in clinical BRD cases, some also exist as normal flora suggesting their presence in the upper airways alone is not necessarily informative with respect to disease status or risk. To determine the relationship between presence, load and disease status, we investigated the relationship between load in the upper airways at induction and active BRD cases in feedlot cattle using efficiency-corrected PCR quantification. By this approach, we were able to accurately determine the prevalence and load of the key BRD agents in the upper respiratory tract showing that cattle in the hospital pen had a higher prevalence, and load, of these agents both singly and in combination compared to cattle sampled at feedlot induction. A combination of agents was the most accurate indicator of BRD risk with cattle with four or more agents detected in the upper airway more likely to be undergoing treatment for BRD than non-BRD ailments. In addition, M. bovis was rarely detected at feedlot induction but was identified at high prevalence in cattle in the hospital pen. These findings present a potential new technological approach for the investigation, analysis and identification of BRD-associated viral and bacterial agents for Australian feedlot systems as well as for BRD disease management and treatment.

Relative perceptions of prevalence, impact and importance of photosensitisation in Australian livestock: A survey of veterinarians, livestock traders and livestock producers

AIMS

To investigate the relative differences in the perceptions and awareness of outbreaks of photosensitisation in Australian livestock stakeholders, including veterinarians, livestock traders and producers.

METHODS

A questionnaire was developed and circulated to livestock veterinarians, producers and traders in Australia via email addresses obtained from public access sources. The questionnaire was designed to evaluate participants' awareness and perception of health, welfare, and production issues associated with outbreaks of photosensitisation and towards the incidence and importance of photosensitisation in livestock.

RESULTS

One hundred and twenty-eight online responses were received in total. Nearly half of the respondents (49.0%) indicated they would encounter 1-3 outbreaks annually. The majority of veterinarian and livestock producers stated that outbreaks of photosensitisation were common and economically important, with cattle and sheep being equally considered as susceptible species to this condition, and secondary (hepatogeneous) photosensitisation is the most common type.

CONCLUSION

This survey confirms the anecdotal evidence that photosensitisation in livestock in Australia is commonly encountered by veterinarians and livestock producers. However, there is no industry-wide common acceptance of the issue, broader opinions should be canvassed when considering impacts on stakeholders regarding photosensitisation outbreaks in livestock in Australia or abroad in the future.

Timed environmental exposure indicates sample stability for reliable noninvasive measurement of fecal cortisol metabolite concentrations in sheep

The use of noninvasive techniques to evaluate stress responses in animals has become an increasingly popular method of animal welfare assessment in both production animals and wildlife. In particular, using fecal samples to measure fecal cortisol metabolites (FCMs) as a quantitative measure has proven ideal as samples can be collected remote to the animal after defecation without the need for invasive procedures. Colorimetric enzyme immunoassays (EIAs) have been shown to have a high level of selectivity and sensitivity for FCM concentration analysis, equivalent to the traditionally used radioimmunoassay. Regardless of the assay system used, species- and sample-specific validation must be undertaken to ensure the reliability of results, particularly where sampling is undertaken in a novel species or where environmental conditions might impact FCM stability in the fecal sample. To determine the limit of environmental exposure acceptable for analysis of FCM concentrations in ovine scat samples collected from a paddock under conditions of stable heat and humidity, this study quantified FCMs in ovine feces shortly after defecation (2-7 h) and after timed environmental exposure (1-9 d). Samples were determined to show stable FCM concentrations for up to 5 d by this analysis. Understanding the impacts of environmental exposure, and therefore the viability of remote fecal collection methods for quantitative analysis of FCM by EIA, is important to assess the utility of noninvasive measures of endocrine status in animals where the exact timing of defecation may not be known.

Treatment with potassium bromide mitigates ataxia and reduces tremor in lambs with perennial ryegrass toxicosis

Aims: To assess the use of potassium bromide (KBr) as a therapeutic intervention for perennial ryegrass toxicosis (PRGT) in lambs fed ryegrass seed containing lolitrem B. Methods: Male lambs aged 10-12 months (n = 43) were assigned to receive ryegrass seed containing lolitrem B, at a dose of 0.16 mg/kg/day (Groups 2, 3 and 4), or lucerne chaff and molasses (Groups 1 and 5). Lambs in Groups 2 and 3 were observed for clinical signs and gait changes until defined signs of PGRT were observed, when they were transferred, with lambs in Group 1, to the Testing phase of the trial. Lambs in Group 3 were then treated with a single oral dose of 300 mg/kg bromide. Lambs in Groups 4 and 5 received KBr daily from the start of the trial (540 mg/kg bromide over 3 days then 20 mg/kg daily) and were transferred to the Testing phase after 18 days. Clinical examination and gait assessment, and surface electromyography of the triceps muscle, measuring root-mean-square (RMS) voltages, were carried out on Days 0, 1 and 2 of the Testing phase followed by necropsy, histopathology, measurement of concentrations of bromide in serum and CSF and faecal cortisol metabolites (FCM). Results: In Group 3 lambs, mean composite gait scores decreased between Testing phase Day 0 and Days 1 and 2 (p < 0.001), but increased in lambs in Group 2 between Day 0 and Day 2 (p = 0.015). Scores for lambs in Group 3 on Day 2 were lower than for lambs in Group 2 (p < 0.001). Mean RMS voltages on Day 2 were higher in lambs in Group 2 than Group 3 (p = 0.045). Mean concentrations of bromide in serum were >800 µg/mL in lambs in Groups 3 and 4 on Day 2. Concentrations of FCM were higher in lambs from Group 2 than in Groups 1 or 5, but were similar in Groups 2, 3 and 4. Histopathological findings in the cerebellum of lambs from Groups 2, 3 and 4 were similar, showing pyknosis of neurons within the granular layer of the cerebellum and Purkinje neuron proximal axonal spheroid formation. Conclusions and clinical relevance: A single oral dose of 300 mg/kg bromide in lambs with neurological signs of PRGT resulted in reduced composite gait scores and reduced RMS voltages, indicating a significant improvement in clinical signs of ataxia, movement disorder and muscle tremor associated with the neurotoxic effects of lolitrem B.

A single exposure to the tremorgenic mycotoxin lolitrem B inhibits voluntary motor activity and spatial orientation but not spatial learning or memory in mice

The indole diterpenoid toxin lolitrem B is a tremorgenic agent found in the common grass species, perennial ryegrass (Lolium perenne). The toxin is produced by a symbiotic fungus Epichloë festucae (var. lolii) and ingestion of infested grass with sufficient toxin levels causes a movement disorder in grazing herbivores known as 'ryegrass staggers'. Beside ataxia, lolitrem B intoxicated animals frequently show indicators of cognitive dysfunction or exhibition of erratic and unpredictable behaviours during handling. Evidence from field cases in livestock and controlled feeding studies in horses have indicated that intoxication with lolitrem B may affect higher cortical or subcortical functioning. In order to define the role of lolitrem B in voluntary motor control, spatial learning and memory under controlled conditions, mice were exposed to a known dose of purified lolitrem B toxin and tremor, coordination, voluntary motor activity and spatial learning and memory assessed. Motor activity, coordination and spatial memory were compared to tremor intensity using a novel quantitative piezo-electronic tremor analysis. Peak tremor was observed as frequencies between 15 and 25Hz compared to normal movement at approximately 1.4-10Hz. A single exposure to a known tremorgenic dose of lolitrem B (2 mg/kg IP) induced measureable tremor for up to 72 h in some animals. Initially, intoxication with lolitrem B significantly decreased voluntary movement. By 25 h post exposure a return to normal voluntary movement was observed in this group, despite continuing evidence of tremor. This effect was not observed in animals exposed to the short-acting tremorgenic toxin paxilline. Lolitrem B intoxicated mice demonstrated a random search pattern and delayed latency to escape a 3 h post intoxication, however by 27 h post exposure latency to escape matched controls and mice had returned to normal searching behavior indicating normal spatial learning and memory. Together these data indicate that the tremor exhibited by lolitrem B intoxicated mice does not directly impair spatial learning and memory but that exposure does reduce voluntary motor activity in intoxicated animals. Management of acutely affected livestock suffering toxicosis should be considered in the context of their ability to spatially orientate with severe toxicity.

Development of a model for investigation of perennial ryegrass toxicosis in sheep

AIMS To develop a clinical model of perennial ryegrass toxicosis (PRGT) based on feeding a known dose of lolitrem B and ergotamine, and to produce a consistent clinical presentation for assessment of disease pathophysiology, neurological changes and neurohistopathology. METHODS Male lambs, aged between 10-12 months, were randomly assigned to either Treatment (n=9) or Control (n=9) groups. Lambs in the Treatment group received feed containing a novel endophyte-infested perennial ryegrass seed, commencing on Day 0 of the Feeding phase with a low induction dose, then increasing after 3 days to provide 0.16 mg/kg live bodywight (LBW)/day of lolitrem B and 0.054 mg/kg LBW/day ergotamine. Lambs were examined daily and when defined signs of PRGT were observed they were transferred to the Testing phase. Neurological examinations, assessment of gait, surface electromyography (EMG) and mechanosensory nociceptive threshold testing were carried out and blood samples collected during both phases of the trial, with a full necropsy, histopathological examination and measurement of faecal cortisol metabolites (FCM) performed on Day 2 of the Testing phase. RESULTS Typical clinical signs of PRGT, including ataxia of vestibulocerebellar origin leading to stumbling, were observed in all Treatment lambs. The median interval from the start of the Feeding phase to entry into the Testing phase was 21 (min 18, max 34) days. Histopathological characterisation of neurological lesions included the presence of Purkinje cell vacuolation, pyknotic granular layer neurons and proximal axonal Purkinje cell spheroids. Lesions were most apparent within the vestibulocerebellum. Mean root-mean-square voltages from triceps EMG increased in Treatment lambs between Feeding phase Day 0 and Testing phase Day 2 (p<0.001). Daily water intake during the Testing phase for the Treatment group was less than in Control group lambs (p=0.002), and concentrations of FCM at necropsy were higher in Treatment compared to Control lambs (p=0.02). CONCLUSIONS AND CLINICAL RELEVANCE Lolitrem B and ergotamine dosing in feed on a live weight basis combined with neurological/gait assessment provides an effective model for investigation of PRGT and potential therapeutics. Assessment of gait changes using defined criteria and RMS voltages from EMG appear to be useful tools for the assessment of the severity of neurological changes.

Extended Asymmetrical Pedicle Subtraction Osteotomy for Adult Spinal Deformity: 2-Dimensional Operative Video

Pedicle subtraction osteotomy (PSO) is an effective technique to correct fixed sagittal malalignment. A variation of this technique, the “trans-discal” or “extended” PSO (Schwab grade IV osteotomy), involves extending the posterior wedge resection of the index vertebra to include the superior adjacent disc for radical discectomy. The posterior wedge may be resected in asymmetric fashion to correct concurrent global coronal malalignment.

This video illustrates the technical nuances of an extended asymmetrical lumbar PSO for adult spinal deformity. A 62-yr-old female with multiple prior lumbar fusions presented with worsening back pain and posture. Preoperative scoliosis X-rays demonstrated severe global sagittal and coronal malalignment (sagittal vertical axis [SVA, C7-plumbline] of 13.5 cm, pelvic incidence [PI] of 60°, lumbar lordosis [LL] of 14° [in kyphosis], pelvic tilt [PT] of 61°, thoracic kyphosis [TK] of 18°, and rightward coronal shift of 9.3 cm). The patient gave informed consent to surgery and for use of her imaging for medical publication. Briefly, surgery first involved transpedicular instrumentation from T10 to S1 with bilateral iliac screw fixation, and then T11-12 and T12-L1 Smith-Petersen osteotomies were performed. Next, an extended asymmetrical L4 PSO was performed and a 12° lordotic cage (9 × 14 × 40 mm) was placed at the PSO defect. Rods were placed from T10 to iliac bilaterally, and accessory supplemental rods spanning the PSO were attached. Postoperative scoliosis X-rays demonstrated improved alignment: SVA 5.5 cm, PI 60°, LL 55°, PT 36°, TK 37°, and 3.7 cm of rightward coronal shift. The patient had uneventful recovery.

A Pilot Study on Posterior Polyethylene Tethers to Prevent Proximal Junctional Kyphosis After Multilevel Spinal Instrumentation for Adult Spinal Deformity

BACKGROUND

Proximal junctional kyphosis (PJK) is a common problem after multilevel spine instrumentation.

OBJECTIVE

To determine if junctional tethers reduce PJK after multilevel instrumented surgery for adult spinal deformity (ASD).

METHODS

ASD patients who underwent posterior instrumented fusion were divided into 3 groups: no tether (NT), polyethylene tether-only (TO; tied securely through the spinous processes of the uppermost instrumented vertebra [UIV] + 1 and UIV-1), and tether with crosslink (TC; passed through the spinous process of UIV+1 and tied to a crosslink between UIV-1 and UIV-2). PJK was defined as proximal junctional angle ≥ 10° and ≥ 10° greater than the corresponding preoperative measurement.

RESULTS

One hundred eighty-four (96%) of 191 consecutive patients achieved minimum 3-mo follow-up (mean = 20 mo [range:3-56 mo]; mean age = 66 yr; 67.4% female). There were no significant differences between groups based on demographic, surgical, and sagittal radiographic parameters. PJK rates were 45.3% (29/64), 34.4% (22/64), and 17.9% (10/56) for NT, TO, and TC, respectively. PJK rate for all tethered patients (TO + TC; 26.7% [32/120]) was significantly lower than NT (P = .011). PJK rate for TC was significantly lower than NT (P = .001). Kaplan-Meier analysis showed significant time-dependent PJK reduction for TC vs NT (log rank test, P = .010). Older age and greater change in lumbar lordosis were independent predictors of PJK, while junctional tethers had a significant protective effect.

CONCLUSION

Junctional tethers significantly reduced occurrence of PJK. This difference was progressive from NT to TO to TC, but only reached pairwise significance for NT vs TC. This suggests potential benefit of tethers to reduce PJK, and that future prospective studies are warranted.

An outbreak of primary photosensitisation in lambs secondary to consumption of Biserrula pelecinus (biserrula)

CASE REPORT

An outbreak of photosensitisation affecting approximately 25% of a flock of 120 meat lambs that was grazing a monoculture of the pasture legume Biserrula pelecinus var. Casbah (biserrula) was investigated. Blood samples were taken from sheep with moderate to severe clinical signs, and from apparently normal animals, for a complete blood count and biochemistry; 5 affected animals were subjected to a full necropsy. Histopathological investigation showed lesions consistent with photosensitisation of the exposed unpigmented skin of the face and ears. No histopathological or clinical pathological abnormalities suggestive of a hepatopathy were detected in any of the cases, indicating that the lesions observed in this flock were caused by a primary photosensitising agent present in B. pelecinus.

CONCLUSION

This is the first confirmation that photosensitisation caused by ingestion of biserrula is caused by a primary photosensitising agent.

Acute renal failure associated with Amaranthus species ingestion by lambs

CASE REPORT

This report documents an outbreak of acute renal failure in a flock of 9-month-old White Suffolk-cross ewe lambs. The mortality rate was moderate but the morbidity was high. The lambs had grazed a wheat stubble paddock in which there were several weed species, including Amaranthus spp.

CLINICAL SIGNIFICANCE

Renal failure in livestock has been reported internationally following the ingestion of Amaranthus spp. and although it has previously been suspected in Australia no cases have been documented. It is important for Australian veterinarians and farmers to realise the toxic potential of this group of plants.

Systematic variational method for statistical nonlinear state and parameter estimation

In statistical data assimilation one evaluates the conditional expected values, conditioned on measurements, of interesting quantities on the path of a model through observation and prediction windows. This often requires working with very high dimensional integrals in the discrete time descriptions of the observations and model dynamics, which become functional integrals in the continuous-time limit. Two familiar methods for performing these integrals include (1) Monte Carlo calculations and (2) variational approximations using the method of Laplace plus perturbative corrections to the dominant contributions. We attend here to aspects of the Laplace approximation and develop an annealing method for locating the variational path satisfying the Euler-Lagrange equations that comprises the major contribution to the integrals. This begins with the identification of the minimum action path starting with a situation where the model dynamics is totally unresolved in state space, and the consistent minimum of the variational problem is known. We then proceed to slowly increase the model resolution, seeking to remain in the basin of the minimum action path, until a path that gives the dominant contribution to the integral is identified. After a discussion of some general issues, we give examples of the assimilation process for some simple, instructive models from the geophysical literature. Then we explore a slightly richer model of the same type with two distinct time scales. This is followed by a model characterizing the biophysics of individual neurons.

Anterior surgical treatment of cervical spondylotic myelopathy: review article

BACKGROUND

Cervical spondylotic myelopathy (CSM) is a common indication for cervical spine surgery. Surgical options include anterior, posterior, or combined procedures each with specific advantages and disadvantages.

QUESTIONS/PURPOSES

This article will provide a description of the various anterior alternatives and discuss the available evidence used in guiding the surgical decision making process with the aim of answering the following questions: (1) What anatomical/disease related factors favor anterior over posterior surgeries? (2) What are the common anterior procedures and how safe and effective are they? (3) What are the most effective options for multilevel CSM? (4) Is there a role for motion preservation? An additional objective is to discuss technical advances that have improved success rates for anterior procedures.

METHODS

The PubMed database was searched. Keywords were CSM and anterior surgery. Three hundred eighty two articles were found one hundred three were reviewed. Articles describing anterior cervical techniques were selected along with studies describing the various anterior techniques or comparisons of anterior to posterior techniques.

RESULTS

Anterior decompression and fusion procedures are more effective than posterior procedures for patients with primarily ventrally located compression especially in the presence of cervical kyphosis. ACDF, ACCF, and hybrid combinations are safe and effective treatment options for multilevel CSM. Anterior procedures may be more cost effective and result in significantly improved postoperative quality of life and health-related quality of life measures compared to posterior procedures.

CONCLUSION

Anterior cervical decompression techniques are safe and effective in the treatment of CSM. Anterior surgeries may be preferable to posterior approaches, when considering health-related quality of life measures and cost effectiveness.

Evidence of dehydration and electrolyte disturbances in cases of perennial ryegrass toxicosis in Australian sheep

CASE REPORT

Perennial ryegrass toxicosis (PRGT) is a common disease entity in Australia, presenting as an association of clinical signs including alterations in normal behavioural, ataxia ('staggers'), ill thrift and gastrointestinal dysfunction ('scours'). Clinical signs can range in severity from mild (gait abnormalities and failure to thrive) to severe (seizures, lateral recumbency and death). Presentation across the flock is usually highly variable. PRGT is caused by toxins produced by the endophytic fungus Neotyphodium lolii, a symbiont of perennial ryegrass that is present in pastures across the temperate regions of Australia and Tasmania. A particular feature of PRGT in Australia is the occasional occurrence of large-scale sheep losses, suggesting other factors are influencing mortality rates compared with other PRGT risk zones such as North America and New Zealand. During 2011, producers in the state of Victoria experienced a mild outbreak of PRGT that affected large numbers of animals but with limited mortalities. Clinical samples taken from affected sheep showed a high incidence of dehydration and electrolyte abnormalities.

CONCLUSION

We speculate that changes in hydration status may be a contributory aetiological factor in those years in which high numbers of deaths are associated with PRGT outbreaks in Australia.

A comparative analysis of minimally invasive and open spine surgery patient education resources

Object

The Internet has become a widespread source for disseminating health information to large numbers of people. Such is the case for spine surgery as well. Given the complexity of spinal surgeries, an important point to consider is whether these resources are easily read and understood by most Americans. The average national reading grade level has been estimated to be at about the 7th grade. In the present study the authors strove to assess the readability of open spine surgery resources and minimally invasive spine surgery resources to offer suggestions to help improve the readability of patient resources.

Methods

Online patient education resources were downloaded in 2013 from 50 resources representing either traditional open back surgery or minimally invasive spine surgery. Each resource was assessed using 10 scales from Readability Studio Professional Edition version 2012.1.

Results

Patient education resources representing traditional open back surgery or minimally invasive spine surgery were all found to be written at a level well above the recommended 6th grade level. In general, minimally invasive spine surgery materials were written at a higher grade level.

Conclusions

The readability of patient education resources from spine surgery websites exceeds the average reading ability of an American adult. Revisions may be warranted to increase quality and patient comprehension of these resources to effectively reach a greater patient population.

Vascular inflammation with eosinophils after the use of n-butyl cyanoacrylate liquid embolic system

OBJECTIVE AND IMPORTANCE

Currently, n-butyl cyanoacrylate (n-BCA) is one of the most widely used liquid embolic agents in the treatment of intracranial arteriovenous malformations (AVMs). The cases of three patients are reported who underwent endovascular embolization with n-BCA, followed by resection in two and post-embolization hemorrhage with emergent evacuation in one, with histologic demonstration of an eosinophilic vasculitis found in resected AVM specimens. This is probably the first report of this tissue reaction, which may have theoretically serious clinical implications.

CLINICAL PRESENTATION

In this series, three patients (2 women, 1 man) presented with intracranial AVMs (Spetzler-Martin I-III) with the lesions located in the frontal lobe in two of the patients and in the parietal lobe in one. All patients presented with headache, and one also had new-onset seizures.

INTERVENTION

All patients underwent embolization with n-BCA before a planned, staged surgical resection of the embolized AVMs. One patient had four embolizations over a 5-month period, one had three embolizations over 3 months complicated by hemorrhage after embolization requiring emergent evacuation of the hematoma, and the third patient had a single embolization. In all three patients, surgical and autopsy specimens showed an inflammatory response within the embolized vasculature with a prominent eosinophilic infiltrate.

CONCLUSION

The eosinophilic vasculitis seen in the pathology specimens may represent a previously undocumented hypersensitivity reaction following exposure to n-BCA, with the potential for adverse sequelae, including increased risk of hemorrhage as was seen in one of our patients.

Parameter and state estimation of experimental chaotic systems using synchronization

We examine the use of synchronization as a mechanism for extracting parameter and state information from experimental systems. We focus on important aspects of this problem that have received little attention previously and we explore them using experiments and simulations with the chaotic Colpitts oscillator as an example system. We explore the impact of model imperfection on the ability to extract valid information from an experimental system. We compare two optimization methods: an initial value method and a constrained method. Each of these involves coupling the model equations to the experimental data in order to regularize the chaotic motions on the synchronization manifold. We explore both time-dependent and time-independent coupling and discuss the use of periodic impulse coupling. We also examine both optimized and fixed (or manually adjusted) coupling. For the case of an optimized time-dependent coupling function u(t) we find a robust structure which includes sharp peaks and intervals where it is zero. This structure shows a strong correlation with the location in phase space and appears to depend on noise, imperfections of the model, and the Lyapunov direction vectors. For time-independent coupling we find the counterintuitive result that often the optimal rms error in fitting the model to the data initially increases with coupling strength. Comparison of this result with that obtained using simulated data may provide one measure of model imperfection. The constrained method with time-dependent coupling appears to have benefits in synchronizing long data sets with minimal impact, while the initial value method with time-independent coupling tends to be substantially faster, more flexible, and easier to use. We also describe a method of coupling which is useful for sparse experimental data sets. Our use of the Colpitts oscillator allows us to explore in detail the case of a system with one positive Lyapunov exponent. The methods we explored are easily extended to driven systems such as neurons with time-dependent injected current. They are expected to be of value in nonchaotic systems as well. Software is available on request.

PIAS1 confers DNA-binding specificity on the Msx1 homeoprotein

The mechanisms by which homeoproteins bind selectively to target genes in vivo have long remained unresolved. Here we report that PIAS1 confers DNA-binding specificity on the Msx1 homeoprotein by regulating its subnuclear localization and proximity to target genes. We demonstrate that the interaction of Msx1 with PIAS1, but not its sumoylation, is required for Msx1 to function as an inhibitor of myoblast differentiation through repression of myogenic regulatory genes, such as MyoD. We find that PIAS1 enables Msx1 to bind selectively to a key regulatory element in MyoD, the CER, in myoblast cells and to distinguish the CER from other nonregulatory TAAT-containing sequences. We show that PIAS1 is required for the appropriate localization and retention of Msx1 at the nuclear periphery in myoblast cells. Furthermore, we demonstrate that myogenic regulatory genes that are repressed by Msx1, namely MyoD and Myf5, are located at the nuclear periphery in myoblast cells. We propose that a key regulatory event for DNA-binding specificity by homeoproteins in vivo is their appropriate targeting to subnuclear compartments where their target genes are located, which can be achieved by cofactors such as PIAS1.

Shrinkage stresses in bone cement

Shrinkage of bone cement is reported primarily as a consequence of polymerisation, however thermal shrinkage also occurs as a result of its exothermic reaction. It is proposed that the latter effect is important, since it occurs late in the curing cycle at a time when the cement has attained its mechanical properties as a solid, and that residual stresses result. Observations from experiments and literature reports suggest that residual stresses may be sufficient to initiate cracks at the interface between hip replacement stems and cement.A theoretical model has been developed to calculate interference stresses, using thick-walled cylinder theory, on the basis of thermal and total shrinkages. Thermal shrinkage values were calculated using the coefficient of linear thermal expansion of bone cement, while total shrinkages were measured. Moduli of elasticity values were measured for acrylic bone cements ranging from 2.1 to 2.7GPa, as were Poisson's ratio values ranging from 0.38 to 0.46. Theoretical calculation of stresses in a cement mantle, based on assumptions of thermal shrinkage alone, predicted circumferential stresses of 8.4-25.2MPa for cement curing temperatures in the range 60-140 degrees C. It is concluded that cracks observed around hip prosthesis stems in laboratory specimens of bone cement are due to shrinkage and that residual stresses are sufficient to cause crack initiation prior to functional loading.

Activation of extracellular-regulated kinase by 5-hydroxytryptamine(2A) receptors in PC12 cells is protein kinase C-independent and requires calmodulin and tyrosine kinases

5-Hydroxytryptamine (5-HT)(2A) receptors have been implicated to play a role in both the treatment and pathophysiology of a number of psychiatric disorders. Therefore, the coupling of this receptor to signals, such as extracellular signal-regulated kinase (ERK), that elicit long-term neuronal changes may be relevant. In the present study we examined the coupling of the G(q)-coupled receptor to ERK in PC12 cells, a cell line commonly used as a neuronal model system. Activation of ERK occurred through a pathway different than the protein kinase C-dependent pathways described previously in studies of non-neuronal cells. Activation of ERK, in PC12 cells, was inhibited by both chelation of extracellular Ca(2+) and by depletion of intracellular Ca(2+) stores. Surprisingly, activation was not inhibited, but actually potentiated, by a variety of protein kinase C inhibitors covering all known protein kinase C isoforms. In contrast, the coupling of receptor to activation of ERK was found to be sensitive to N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide hydrochloride (W7) and N-(4-aminobutyl)-5-chloro-1-naphthalenesulfonamide (W13), inhibitors of calmodulin, but not to 1-(N,O-bis[5-isoquinolinesulfonyl]-N-methyl-L-tyrosyl)-4-phenylpiperazine (KN62) and 2-[N-(2-hydroxyethyl)]-N-4-methoxybenzenesulfonyl)]amino-N-(4-chlorocinnamyl)-N-methylbenzylamine) (KN93), inhibitors of calmodulin-dependent protein kinase. Additionally, the general tyrosine kinase inhibitor genistein, as well as the Src inhibitor PP1 and the epidermal growth factor receptor kinase inhibitor 4-(3-chloroanilino)-6,7-dimethoxyquinazoline (AG 1478), inhibited receptor-mediated activation of ERK, suggesting a role for tyrosine kinases. In fact, 5-HT was found to stimulate tyrosine phosphorylation of a number of proteins, and this phosphorylation was inhibited by W7. 5-HT(2A) receptor-activation of ERK through a protein kinase C-independent pathway requiring Ca(2+)/calmodulin/tyrosine kinases represents a pathway distinct from those described in studies of non-neuronal cells.

Primary defects in the lens underlie complex anterior segment abnormalities of the Pax6 heterozygous eye

We describe lens defects in heterozygous small eye mice, and autonomous deficiencies of Pax6(+/-) cells in the developing lens of Pax6(+/+) <--> Pax6(+/-) chimeras. Two separate defects of the lens were identified by analyzing the distribution of heterozygous cells in chimeras: Pax6(+/-) cells are less readily incorporated into the lens placode than wild type, and those that are incorporated into the lens are not maintained efficiently in the proliferating lens epithelium. The lens of chimeric eyes is, therefore, predominantly wild type from embryonic day 16.5 onwards, whereas heterozygous cells contribute normally to all other eye tissues. Eye size and defects of the iris and cornea are corrected in fetal and adult chimeras with up to 80% mutant cells. Therefore, these aspects of the phenotype may be secondary consequences of primary defects in the lens, which has clinical relevance for the human aniridia (PAX6(+/-)) phenotype.

Genetic background effects on dental and other craniofacial abnormalities in homozygous small eye (Pax6Sey/Pax6Sey) mice

Small eye (Pax6Sey) is a semi-dominant mutation affecting development of the eyes, brain and nasal structures. The mutant phenotype arises from defects within the Pax6 gene and several mutant alleles have been identified. A previous study reported that Pax6Sey/Pax6Sey homozygotes, in a random-bred stock, had a median cartilaginous rod-like structure in the nasal region and 80% had supernumerary upper incisor teeth. In this study we show that supernumerary upper incisor teeth and a previously unreported nasal capsule-derived cartilaginous 'spur' occur in compound heterozygous Pax6Sey-Neu/Pax6Sey and homozygous Pax6Sey/Pax6Sey fetuses from several strains of mice. The frequencies of the abnormal phenotypes were not related to allele type but showed variable penetrance, which was dependent on genetic background. The median nasal cartilaginous rod-like structure was present in all homozygous small eye fetuses. The Pax6Sey/Pax6Sey homozygote may provide insight into the complex gene interactions involved in eye, nasal and craniofacial morphogenesis.

Multiple functions for Pax6 in mouse eye and nasal development

Mouse embryos, homozygous for the small eye (Sey) mutation die soon after birth with severe facial abnormalities that result from the failure of the eyes and nasal cavities to develop. Mutations in the Pax6 gene are responsible for the Sey phenotype. As a general disruption of eye and nasal development occurs in the homozygous Sey embryos, it is unclear, from the mutant phenotype alone, which tissues require functional Psx6. To examine the roles for Pax6 in eye and nasal development we produced chimeric mouse embryos composed of wild-type and Sey mutant cells. In these embryos we found that mutant cells were excluded from both the lens and nasal epithelium. Both of these tissues were smaller, and in some cases absent, in chimeras with high proportions of mutant cells. The morphology of the optic cup was also severely affected in these chimeras; mutant cells were excluded from the retinal pigmented epithelium and did not intermix with wild-type cells in other regions. The evidence shows that Pax6 has distinct roles in the nasal epithelium and the principal tissue components of the embryonic eye, acting directly and cell autonomously in the optic cup and lens. We suggest that Pax6 may promote cell surface changes in the optic cup and control the fate of the ectoderm from which the lens and nasal epithelia are derived.

Flow chart eases planning process for hospitals

If planning is the key word for hospitals in the next decade, how do their administrators get through the tedious tasks associated with formulating strategy, making purchases or changing directions for individual units? In the following article, the author suggests a methodology to streamline the process and put it in the hands of department managers.

The nurse manager and ethical choices

Ethical decision making on issues other than those in the clinical area are presenting a special challenge to today's nurse managers. This article discusses some of these issues and presents a model for use in analyzing them. Frequently used ethical principles are also included.