Childhood-Onset Lupus Nephritis in the Childhood Arthritis and Rheumatology Research Alliance Registry: Short-Term Kidney Status and Variation in Care

OBJECTIVE

The goal was to characterize short-term kidney status and describe variation in early care utilization in a multicenter cohort of patients with childhood-onset systemic lupus erythematosus (cSLE) and nephritis.

METHODS

We analyzed previously collected prospective data from North American patients with cSLE with kidney biopsy-proven nephritis enrolled in the Childhood Arthritis and Rheumatology Research Alliance (CARRA) Registry from March 2017 through December 2019. We determined the proportion of patients with abnormal kidney status at the most recent registry visit and applied generalized linear mixed models to identify associated factors. We also calculated frequency of medication use, both during induction and ever recorded.

RESULTS

We identified 222 patients with kidney biopsy-proven nephritis, with 64% class III/IV nephritis on initial biopsy. At the most recent registry visit at median (interquartile range) of 17 (8-29) months from initial kidney biopsy, 58 of 106 patients (55%) with available data had abnormal kidney status. This finding was associated with male sex (odds ratio [OR] 3.88, 95% confidence interval [95% CI] 1.21-12.46) and age at cSLE diagnosis (OR 1.23, 95% CI 1.01-1.49). Patients with class IV nephritis were more likely than class III to receive cyclophosphamide and rituximab during induction. There was substantial variation in mycophenolate, cyclophosphamide, and rituximab ever use patterns across rheumatology centers.

CONCLUSION

In this cohort with predominately class III/IV nephritis, male sex and older age at cSLE diagnosis were associated with abnormal short-term kidney status. We also observed substantial variation in contemporary medication use for pediatric lupus nephritis between pediatric rheumatology centers. Additional studies are needed to better understand the impact of this variation on long-term kidney outcomes.

Intraarticular steroids as DMARD-sparing agents for juvenile idiopathic arthritis flares: Analysis of the Childhood Arthritis and Rheumatology Research Alliance Registry

BACKGROUND

Children with juvenile idiopathic arthritis (JIA) who achieve a drug free remission often experience a flare of their disease requiring either intraarticular steroids (IAS) or systemic treatment with disease modifying anti-rheumatic drugs (DMARDs). IAS offer an opportunity to recapture disease control and avoid exposure to side effects from systemic immunosuppression. We examined a cohort of patients treated with IAS after drug free remission and report the probability of restarting systemic treatment within 12 months.

METHODS

We analyzed a cohort of patients from the Childhood Arthritis and Rheumatology Research Alliance (CARRA) Registry who received IAS for a flare after a period of drug free remission. Historical factors and clinical characteristics and of the patients including data obtained at the time of treatment were analyzed.

RESULTS

We identified 46 patients who met the inclusion criteria. Of those with follow up data available 49% had restarted systemic treatment 6 months after IAS injection and 70% had restarted systemic treatment at 12 months. The proportion of patients with prior use of a biologic DMARD was the only factor that differed between patients who restarted systemic treatment those who did not, both at 6 months (79% vs 35%, p < 0.01) and 12 months (81% vs 33%, p < 0.05).

CONCLUSION

While IAS are an option for all patients who flare after drug free remission, it may not prevent the need to restart systemic treatment. Prior use of a biologic DMARD may predict lack of success for IAS. Those who previously received methotrexate only, on the other hand, are excellent candidates for IAS.

Inequalities in accessing quality healthcare, does insurance play a role? retrospective analysis of aortic emergencies from national inpatient sample 2019

Background

Aortic emergencies, dissection and rupture, are rare but catastrophic entities, with the cornerstone to survival being prompt diagnosis and treatment. Insurance status often limits access to healthcare, and our study aims to determine if it plays a role in the outcomes of aortic emergencies.

Method

A retrospective analysis of the 2019 Nationwide Inpatient Sample was conducted to identify hospitalization (Age ≥18 & non-elective) with aortic dissection and ruptured aortic aneurysms using ICD-10 codes. Discharge-level weight analysis was used to produce a national estimate. Variables were screened with univariate regression, and intermediate and co-linear variables were screened-out before a multivariable regression analysis model was built and performed to calculate the odds ratio.

Results

A total of 19,685 (0.06%) hospitalizations are identified for aortic emergencies (14965 dissections & 4720 ruptured aneurysms). The mean age was 58.56, 62.7% were males, and ethnic distribution was 65.1% white, 19.5% blacks, 7.6% Hispanics, and others.

11.4% of the hospitalizations underwent diagnostic imaging with either CTA/MRA/TEE/Aortography within 24 hours. Hypotension/shock was present in 32% of these hospitalizations and was a risk factor for mortality OR 3.21 (p&lt;0.00), increasing LOS by an average of 5.1 days and resource utilization by 156,000$. Another risk factor for mortality was stroke/TIA (OR-1.76, p&lt;0.00), increasing LOS and resource utilization by 3.1 days and 80,662$, respectively.

3220 hospitalizations (16.4%) did not survive the course, and the mortality rate in uninsured, Medicare, and Medicaid was 17%, 20%,9% compared with 12% in privately insured. On crude analysis, uninsured and medicare patients appeared to have higher odds of mortality [OR 1.50, p&lt;0.04, and OR 1.83 p-value &lt;0.002 respectively], however upon adjusting for confounders, only uninsured patients showed statistically significant difference (OR 2.13, p&lt;0.002). Similar results were corroborated on analyzing hospitalizations for aortic dissection; however, insurance status did not influence mortality in a ruptured aneurysm.

When comparing hospitalization of median household income of ≥79,000$ with household of median income of 59,000–78,999 $, 46,000–58,999 $ and &lt;46,000$ had higher odds of mortality (OR-1.38, p&lt;0.04), (OR-1.44, p&lt;0.02) and (OR-1.44, p&lt;0.03) respectively. Of all the insurance types, a statistically significant difference compared with private insurance, Medicaid on average, had 2.8 more days and incurred an additional 62,912$ in resource utilization (p&lt;0.00).

Conclusion

Inequalities in accessing healthcare, median household income, and insurance status are risk factors for mortality in aortic emergencies. Efforts are needed to bridge the gap in this particular facet of social determinants of health to find a sustainable and equitable solution for quality healthcare for aall regardless of their insurance status.

Funding Acknowledgement

Type of funding sources: None.

Social determinants of health influence disease activity and functional disability in Polyarticular Juvenile Idiopathic Arthritis

BACKGROUND

Social determinants of health (SDH) greatly influence outcomes during the first year of treatment in rheumatoid arthritis, a disease similar to polyarticular juvenile idiopathic arthritis (pJIA). We investigated the correlation of community poverty level and other SDH with the persistence of moderate to severe disease activity and functional disability over the first year of treatment in pJIA patients enrolled in the Childhood Arthritis and Rheumatology Research Alliance Registry.

METHODS

In this cohort study, unadjusted and adjusted generalized linear mixed effects models analyzed the effect of community poverty and other SDH on disease activity, using the clinical Juvenile Arthritis Disease Activity Score-10, and disability, using the Child Health Assessment Questionnaire, measured at baseline, 6, and 12 months.

RESULTS

One thousand six hundred eighty-four patients were identified. High community poverty (≥20% living below the federal poverty level) was associated with increased odds of functional disability (OR 1.82, 95% CI 1.28-2.60) but was not statistically significant after adjustment (aOR 1.23, 95% CI 0.81-1.86) and was not associated with increased disease activity. Non-white race/ethnicity was associated with higher disease activity (aOR 2.48, 95% CI: 1.41-4.36). Lower self-reported household income was associated with higher disease activity and persistent functional disability. Public insurance (aOR 1.56, 95% CI 1.06-2.29) and low family education (aOR 1.89, 95% CI 1.14-3.12) was associated with persistent functional disability.

CONCLUSION

High community poverty level was associated with persistent functional disability in unadjusted analysis but not with persistent moderate to high disease activity. Race/ethnicity and other SDH were associated with persistent disease activity and functional disability.

130 Paediatric Hand Fractures Requiring Surgery – the Results of a Bespoke Hand Surgery Service

Aim

To evaluate the management of The Royal Devon and Exeter Hospital (RD&E) bespoke hand surgery service on paediatric closed hand fractures. In particular, an assessment against The British Society for Surgery of the Hand (BSSH) closed fracture standards on treatment timelines and national guidance compliance.

Method

A retrospective review of all paediatric patients requiring plastic surgery seen at the RD&E plastics trauma clinic from 1st Nov 2020 to 28th Feb 2021 was performed. This was compared to two previous audit cycles completed during winter 2019 and summer 2020. Health informatics was collated via our IT department and thoroughly reviewed using departmental notes. Exclusion criteria included: all non-fracture injuries, patients &gt; 18 years old and open fractures.

Results

In winter 2020–21 all patients were referred the same day of injury and 92% were seen by a Plastic Surgeon within 24 hours of injury. This was an improvement from the mean time from referral to clinic of 5 days in winter 2019 and 1.33 days in summer 2020 respectively. 85% of cases are now operated within 48 hours of review and 92% of cases were operated within 72 hours of the decision to operate where conservative management had failed.

Conclusions

The introduction of a ‘rapid-access’ musculoskeletal unit with early senior review and a dedicated theatre has created ‘gold-standard’ compliance with national standards for the operative management of closed paediatric fractures. We should continue to focus on improving and increasing capacity of this service as it has likely improved both the patient journey and outcomes.

1018 Did COVID Compromise the Care of Closed Paediatric Hand Fractures?

Aim

To assess the effect of a ‘rapid-access’ musculoskeletal unit, established in March 2020, as part of the Royal Devon & Exeter hospital COVID response, with direct assessment of hand trauma by the Plastic Surgery department staff, on treatment timelines and national guidance compliance for closed paediatric hand fractures.

Method

This was a retrospective review from 1st January to 31st December 2019 and a prospective study from the 1st April to 15th June 2020. The retrospective cases were collated by health informatics. The prospective data was recorded on the department’s database. Exclusion criteria: nail bed injuries with tuft fractures, ligament injuries only, open fractures and patients aged 18 at time of surgery.

Results

In 2019 the majority (73%) of patients (n = 26) were referred within 48hrs but waited a median of 5 days to be seen in clinic by a hand surgeon resulting in significant delays in treatment. After service reconfiguration in 2020, all patients (n = 6) were operated on within 72 hours of the decision to operate - mean time to surgery 1.5 days (range 0-3 days). The mean time from referral to clinic was 1.33 days (range 0-6 days). 4 patients were operated on within 7 days of injury. Of the 2 patients operated on &gt; 7 days, 1 was referred 32 days post injury and 1 failed conservative management.

Conclusions

The introduction of a ‘rapid-access’ musculoskeletal unit with early senior review and a dedicated theatre has created ‘gold-standard’ compliance with national standards for the operative management of closed paediatric fractures.

89 Do Corticosteroid and Local Anaesthetic Hip Injections Administered Proximal or Distal to The Zona Orbicularis Have an Effect on Patient Satisfaction?

Aim

Pubofemoral and ischiofemoral ligaments blend to make zona orbicularis. Zonaorbicularis has been suggested to force fluid from peripheral compartment to central compartment in unidirectional flow. This study aims to assess whether injection of corticosteroid with local anaesthetic injected either proximal or distal to the zona orbicularis has effect on patient satisfaction.

Method

This retrospective study investigated consecutive patients undergoing ultrasound guided hip injections at a single centre in the UK between November 2018 and March 2019. Patients were identified using IMPAX© picture archiving and communications system. Radiographs were assessed to see if radiopaque dye and therefore corticosteroid and local anaesthetic had been injected proximal or distal to the zona orbicularis. Clinic letters were accessed on the electronic patient record and we recorded whether patients had pain relief at 24 hours and 2 weeks following hip injection.

Results

133 Patients were identified during the study period, of which 40 were included. At 24 hours post-injection 72% of patients were satisfied and 28% were unsatisfied, for which there was 76% and 70% satisfaction for proximal and distal injections respectively (p = 0.63). At 2 weeks post-injection 45% of patients were satisfied and 55% of patients unsatisfied, for which there was 47% and 44% satisfaction for proximal and distal injections respectively (p = 0.9).

Conclusions

Overall patient satisfaction is high following hip corticosteroid and local anaesthetic injection. No difference was found between injections proximal and distal to the zona orbicularis. Further research is needed to quantify the association between proximal and distal injections.

Wildland Fire Emission Sampling at Fishlake National Forest, Utah Using an Unmanned Aircraft System

Emissions from a stand replacement prescribed burn were sampled using an unmanned aircraft system (UAS, or "drone") in Fishlake National Forest, Utah, U.S.A. Sixteen flights over three days in June 2019 provided emission factors for a broad range of compounds including carbon monoxide (CO), carbon dioxide (CO₂), nitric oxide (NO), nitrogen oxide (NO₂), particulate matter < 2.5 microns in diameter (PM_2.5), volatile organic compounds (VOCs) including carbonyls, black carbon, and elemental/organic carbon. To our knowledge, this is the first UAS-based emission sampling for a fire of this magnitude, including both slash pile and crown fires resulting in wildfire-like conditions. The burns consisted of drip torch ignitions as well as ground-mobile and aerial helicopter ignitions of large stands comprising over 1,000 ha, allowing for comparison of same-species emission factors burned under different conditions. The use of a UAS for emission sampling minimizes risk to personnel and equipment, allowing flexibility in sampling location and ensuring capture of representative, fresh smoke constituents. PM_2.5 emission factors varied 5-fold and, like most pollutants, varied inversely with combustion efficiency resulting in lower emission factors from the slash piles than the crown fires.

Closure of the perineal defect after abdominoperineal excision for rectal adenocarcinoma - ACPGBI Position Statement

BACKGROUND

Perineal wound morbidity is common following abdominoperineal excision of the rectum (APE). There is no consensus on the optimum perineal reconstruction method after APE, and in particular 'extra-levator APE' (ELAPE).

METHODS

A systematic review of the PubMed, Embase and Cochrane databases was performed. This position statement formulated clinical questions and graded the evidence to make recommendations.

RESULTS

Perineal wound complications may be higher following ELAPE compared to 'conventional APE (cAPE)' however there is insufficient evidence to recommend cAPE over ELAPE with regards to the impact upon perineal wound healing. The majority of cAPE studies have used primary closure with varying complication rates reported. Where concerns regarding perineal wound healing exist, myocutaneous flap closure may be considered as an alternative method. There is minimal available evidence on perineal mesh reconstruction following cAPE. Primary closure, mesh use and myocutaneous flap reconstruction following ELAPE has been reported although variations in definitions and low-quality of available evidence limit comparison. There is insufficient evidence to recommend one particular method of perineal closure after ELAPE. Primary perineal closure is likely to have a higher risk of perineal herniation. Myocutaneous flaps and biological mesh have been effectively used in ELAPE closure. There is insufficient evidence to support one particular type of flap or mesh. Perineal wound complication rates are significantly increased when neo-adjuvant radiotherapy is delivered, regardless of surgical technique. There is no evidence that laparoscopy reduces APE perineal wound complications.

CONCLUSION

This position statement updates clinicians on current evidence around perineal closure after APE surgery.

Effect of sodium molybdate supplementation on high concentrations of Cu in liver of yearling bulls

AIM

To determine the impact of sodium molybdate treatment, given weekly, on concentrations of Cu in liver, activity of liver enzymes, and weight gain over 4 weeks, in yearling bulls with elevated concentrations of Cu in liver.

METHODS

The study was carried on two commercial grazing farms in the Otago region of New Zealand in yearling Friesian bulls (n=150 on Farm A and n=49 on Farm B) with mean concentration of Cu in liver >3,000 µmol/kg fresh weight. On Day 0, all animals were weighed and half were systematically allocated to treatment with sodium molybdate (3 mg/kg liveweight on Farm A and 7 mg/kg liveweight on Farm B); the remainder received no treatment (Control). Sodium molybdate was given as a drench weekly for 4 weeks and all animals were weighed again on Day 28. Ten animals on each farm (five from each treatment group) were systematically selected for blood sampling and liver biopsies on Days 0 and 28. Samples were analysed for concentrations of Cu in plasma, vitamin B₁₂ in serum, activities of γ-glutamyl transferase, aspartate aminotransferase and glutamate dehydrogenase in serum, and concentrations of Cu and vitamin B₁₂ in liver. Separate multivariable linear models were used to compare the change in outcome variables between Days 0 and 28 between bulls that had been drenched with sodium molybdate or not.

RESULTS

On Farm A, mean concentrations of Cu in liver on Day 28, as a percentage of concentrations on Day 0, for the control group was 55 (95% CI=40-73)% and for the treatment group was 73 (95% CI=43-111)%. On Farm B, the equivalent mean for the control group was 75 (95% CI=42-131)% and for the treatment group was 85 (95% CI=38-134)%. The multivariable linear models indicated that the changes in concentrations of Cu in liver, activities of liver enzymes and weight gain between Days 0 and 28 did not differ between the bulls treated or not with sodium molybdate (p>0.18).

CONCLUSIONS AND CLINICAL RELEVANCE

Treatment with sodium molybdate in one bolus at weekly intervals for 4 weeks did not affect concentrations of Cu in liver, activity of liver enzymes or weight gain in animals with high concentrations of Cu liver on two farms.

Evidence-based management of adult trigger digits

The aim of this systematic review was to develop an evidence-based guideline to assist clinicians in the treatment of adult trigger digits. There is moderate evidence to suggest that local corticosteroid injection is a safe and effective short-term treatment and it may, therefore, be recommended as an initial treatment for this condition. However, when compared with surgery, there is strong evidence that corticosteroid injection is associated with increased rates of ongoing or recurrent symptoms at 6 months after intervention. There is strong evidence suggesting that trigger digit can be managed safely by surgical release. There is weak evidence to support the use of splinting or other non-operative modalities. Hence a single corticosteroid injection may be offered as the first line in treatment of adult trigger digits, but percutaneous release is a safe alternative. Surgery should be the next line if the injection fails, symptoms recur or the patient chooses.

LEVEL OF EVIDENCE

I.

Cemented or cementless humeral fixation in reverse total shoulder arthroplasty?

Aims

To date, there is insufficient evidence available to compare the outcome of cemented and uncemented fixation of the humeral stem in reverse shoulder arthroplasty (RSA).

Methods

A systemic review comprising 41 clinical studies was performed to compare the functional outcome and rate of complications of cemented and uncemented stems in RSA. These included 1455 cemented and 329 uncemented shoulders. The clinical characteristics of the two groups were similar. Variables were compared using pooled frequency-weighted means and relative risk ratios (RR).

Results

Uncemented stems had a significantly higher incidence of early humeral stem migration (p < 0.001, RR 18.1, 95% confidence interval (CI) 5.0 to 65.2) and non-progressive radiolucent lines (p < 0.001, RR 2.4, 95% CI 1.7 to 3.4), but a significantly lower incidence of post-operative fractures of the acromion compared with cemented stems (p = 0.004, RR 14.3, 95% CI 0.9 to 232.8). There was no difference in the risk of stem loosening or revision between the groups. The cemented stems had a greater relative risk of infection (RR 3.3, 95% CI 0.8 to 13.7), nerve injury (RR 5.7, 95% CI 0.7 to 41.5) and thromboembolism (RR 3.9, 95% CI 0.2 to 66.6). The functional outcome and range of movement were equivalent in the two groups.

Discussion

RSA performed with an uncemented stem gives them equivalent functional outcome and a better complication profile than with a cemented stem. The natural history and clinical relevance of early stem migration and radiolucent lines found with uncemented stems requires further long-term study. Take home message: This study demonstrates that uncemented stems have at least equivalent clinical and radiographic outcomes compared with cemented stems when used for reverse total shoulder arthroplasty. Cite this article: Bone Joint J 2016;98-B:65–74

Direct observation of the coherent nuclear response after the absorption of a photon

How molecules convert light energy to perform a specific transformation is a fundamental question in photophysics. Ultrafast spectroscopy reveals the kinetics associated with electronic energy flow, but little is known about how absorbed photon energy drives nuclear motion. Here we used ultrabroadband transient absorption spectroscopy to monitor coherent vibrational energy flow after photoexcitation of the retinal chromophore. In the proton pump bacteriorhodopsin, we observed coherent activation of hydrogen-out-of-plane wagging and backbone torsional modes that were replaced by unreactive coordinates in the solution environment, concomitant with a deactivation of the reactive relaxation pathway.

Are soft tissue measurements on lateral cervical spine X-rays reliable in the assessment of traumatic injuries?

INTRODUCTION

Traumatic neck pain is a common presentation to the emergency department. Lateral plain radiographs remain the primary investigation in the assessment of these injuries. Soft tissue assessment forms an integral component of these radiographs. They can provide information on subtle injuries that may not be obvious. Many methods are used to assess the prevertebral soft tissue shadows. The two more commonly used techniques include the 'seven at two and two at seven' rule (method 1) and the ratio of the soft tissues with respect to the vertebral width (method 2).

AIM

To assess which of the above two methods in assessing cervical spine soft tissue shadows on lateral radiographs is more sensitive in the presence of cervical spine injuries.

METHODS

A retrospective analysis of consecutive traumatic cervical spine films performed within a busy trauma tertiary centre over a period of 7 months. Patients were divided into two groups: group 1-fractures; group 2-no fractures. The prevertebral soft tissue shadows were measured at referenced points on the lateral cervical spine films with respect to the above two methods and comparisons between the groups were made.

RESULTS

Thirty-nine patients in group 1 were compared to a control group of 60 patients in group 2. Both methods failed to identify any significant differences between the two groups. The sensitivity and specificity for method 1 was 7.6 and 93 %, and for method 2, they were 7.6 and 98 %, respectively.

CONCLUSION

There is no significant difference between the soft tissue shadows when comparing patients with and without cervical spine fractures on lateral radiographs. Both commonly used measures of soft tissue shadows in clinical practice are insensitive in identifying patients with significant osseous injuries. They, therefore, do not offer any further value in interpreting traumatic cervical spine radiographs. The management of patients with cervical spine trauma in the absence of obvious osseous injury on standard radiographs should warrant a computed tomography (CT) scan if clinically indicated.

Inhibition of CXCR3-mediated chemotaxis by the human chemokine receptor-like protein CCX-CKR

BACKGROUND AND PURPOSE

Induction of cellular migration is the primary effect of chemokine receptor activation. However, several chemokine receptor-like proteins bind chemokines without subsequent induction of intracellular signalling and chemotaxis. It has been suggested that they act as chemokine scavengers, which may control local chemokine levels and contribute to the function of chemokines during inflammation. This has been verified for the chemokine-like receptor proteins D6 and DARC as well as CCX-CKR. Here, we provide evidence for an additional biological function of human (h)CCX-CKR.

EXPERIMENTAL APPROACH

We used transfection strategies in HEK293 and human T cells.

KEY RESULTS

Co-expression of hCCX-CKR completely inhibits hCXCR3-induced chemotaxis. We found that hCCX-CKR forms complexes with hCXCR3, suggesting a relationship between CCX-CKR heteromerization and inhibition of chemotaxis. Moreover, negative binding cooperativity induced by ligands both for hCXCR3 and hCCX-CKR was observed in cells expressing both receptors. This negative cooperativity may also explain the hCCX-CKR-induced inhibition of chemotaxis.

CONCLUSIONS AND IMPLICATIONS

These findings suggest that hCCX-CKR prevents hCXCR3-induced chemotaxis by heteromerization thus representing a novel mechanism of regulation of immune cell migration.

The magnetism of surgery: small bowel obstruction in an 8-year-old boy

An 8-year-old boy with Asperger's syndrome presented with right-sided abdominal pain, which was consistent with a probable appendicitis, but revisiting the history with a high index of suspicion confirmed multiple foreign body ingestion to be the cause of his symptoms. An emergency laparotomy was performed. Multiple toy magnets and other metal objects were found, which were causing small bowel obstruction with interloop fistulation. Following removal and repair, the patient made an excellent recovery.

Parental consent for neuroimaging in paediatric research

BACKGROUND

Functional magnetic resonance imaging (fMRI) is increasingly applied in paediatric research. Parents typically provide research consent for their children; yet, no study has examined the rates of consent, nor factors influencing parental decision making for consent. The present study aimed to determine the proportion of parents that would consent to their child undergoing an fMRI study, and to elicit the reasons, motivators and detractors affecting their decision.

METHODS

Ninety parents of children aged 6 years were invited to participate in a postal survey study.

RESULTS

Fifty-three parents (59%) responded and one-third (34%, 18/53) reported that they would consent. The main reason for consent was that participation could benefit children in the future (89%, 16/18). Common reasons for not consenting included that fMRI may be anxiety-provoking (54%), or was an unnecessary medical procedure (23%).

CONCLUSIONS

Our preliminary data suggest that researchers may have to approach three times the number of participants required in order to recruit a suitable number of healthy children to fMRI studies. Further research examining the influence of recruitment approaches (e.g. phone vs. postal) and the various factors influencing decision making regarding consent is required. For example, careful examination of the language used in describing the procedure could facilitate parental understanding about fMRI and alleviate anxiety associated with the procedure. This is an important consideration for recruitment to future fMRI studies given that anxiety was a key factor influencing parental non-consent.

Structural and dynamic studies of the γ-M4 trans-membrane domain of the nicotinic acetylcholine receptor

A structural characterization of a synthetic peptide corresponding to the fourth transmembrane domain (M4-TMD) of the gamma-subunit of the nicotinic acetylcholine receptor from Torpedo californica has been undertaken. Solid-state NMR and CD spectroscopy studies indicate that upon reconstitution into lipid vesicles or magnetically aligned lipid bilayers, the synthetic M4-TMD adopts a linear alpha-helical conformation with the helix aligned within 15 degrees of the membrane normal. Furthermore, analysis of the motional averaging of anisotropic interactions present in the solid-state NMR spectra of the reconstituted peptide, indicate that the dynamics of the peptide within the bilayer are highly sensitive to the phase adopted by the lipid bilayer, providing an insight into how the interaction of lipids with this domain may play a important role in the modulation of this receptor by its lipid environment.

Biophysical characterization of Vpu from HIV-1 suggests a channel-pore dualism

Vpu from HIV‐1 is an 81 amino acid type I integral membrane protein which consists of a cytoplasmic and a transmembrane (TM) domain. The TM domain is known to alter membrane permeability for ions and substrates when inserted into artificial membranes. Peptides corresponding to the TM domain of Vpu (Vpu_1‐32) and mutant peptides (Vpu_1‐32‐W23L, Vpu_1‐32‐R31V, Vpu_1‐32‐S24L) have been synthesized and reconstituted into artificial lipid bilayers. All peptides show channel activity with a main conductance level of around 20 pS. Vpu_1‐32‐W23L has a considerable flickering pattern in the recordings and longer open times than Vpu_1‐32. Whilst recordings for Vpu_1‐32‐R31V are almost indistinguishable from those of the WT peptide, recordings for Vpu_1‐32‐S24L do not exhibit any noticeable channel activity. Recordings of WT peptide and Vpu_1‐32‐W23L indicate Michaelis–Menten behavior when the salt concentration is increased. Both peptide channels follow the Eisenman series I, indicative for a weak ion channel with almost pore like characteristics. Proteins 2008. © 2007 Wiley‐Liss, Inc.

NMR crystallography: the effect of deuteration on high resolution 13C solid state NMR spectra of a 7-TM protein

The effect of deuteration on the 13C linewidths of U-13C, 15N 2D crystalline bacteriorhodopsin (bR) from Halobacterium salinarium, a 248-amino acid protein with seven-transmembrane (7TM) spanning regions, has been studied in purple membranes as a prelude to potential structural studies. Spectral doubling of resonances was observed for receptor expressed in 2H medium (for both 50:50% 1H:2H, and a more highly deuterated form) with the resonances being of similar intensities and separated by <0.3 ppm in the methyl spectral regions in which they were readily distinguished. Line-widths of the methyl side chains were not significantly altered when the protein was expressed in highly deuterated medium compared to growth in fully protonated medium (spectral line widths were about 0.5 ppm on average for receptor expressed both in the fully protonated and highly deuterated media from the C delta, C gamma 1, and C gamma 2 Ile 13C signals observed in the direct, 21-39 ppm, and indirect, 9-17 ppm, dimensions). The measured 13C NMR line-widths observed for both protonated and deuterated form of the receptor are sufficiently narrow, indicating that this crystalline protein morphology is suitable for structural studies. 1) decoupling comparison of the protonated and deuterated bR imply that deuteration may be advantageous for samples in which low power 1H decoupling is required.