Variability in phenylalanine side chain conformations facilitates broad substrate tolerance of fatty acid binding in cockroach milk proteins

Diploptera punctata, also known as the Pacific beetle cockroach, is a viviparous cockroach that gives birth to live offspring and secretes a highly concentrated mixture of glycosylated proteins as a source of nourishment for developing embryos. These proteins are lipocalins that bind to lipids and crystallize in the gut of the embryo. A structure of milk crystals harvested from the embryos showed that the milk-derived crystals were heterogeneous and made of three proteins (called Lili-Mips). We hypothesized that the isoforms of Lili-Mip would display different affinities for fatty acids due to the ability of the pocket to bind multiple acyl chain lengths. We previously reported the structures of Lili-Mip from crystals grown in vivo and recombinantly expressed Lili-Mip2. These structures are similar, and both bind to several fatty acids. This study explores the specificity and affinity of fatty acid binding to recombinantly expressed Lili-Mip 1, 2 & 3. We show that all isoforms can bind to different fatty acids with similar affinities. We also report the thermostability of Lili-Mip is pH dependent, where stability is highest at acidic pH and declines as the pH increases to physiological levels near 7.0. We show that thermostability is an inherent property of the protein, and glycosylation and ligand binding do not change it significantly. Measuring the pH in the embryo's gut lumen and gut cells suggests that the pH in the gut is acidic and the pH inside the gut cells is closer to neutral pH. In various crystal structures (reported here and previously by us), Phe-98 and Phe-100 occupy multiple conformations in the binding pocket. In our earlier work, we had shown that the loops at the entrance could adapt various conformations to change the size of the binding pocket. Here we show Phe-98 and Phe-100 can reorient to stabilize interactions at the bottom of the cavity-and change the volume of the cavity from 510 Å3 to 337 Å3. Together they facilitate the binding of fatty acids of different acyl chain lengths.

Management of glenoid bone loss with impaction and structural bone grafting in reverse shoulder arthroplasty

INTRODUCTION

Glenoid bone loss is a commonly encountered problem in complex primary and revision shoulder arthroplasty. Addressing glenoid bone loss is critical to avoid complications like early loosening, impingement, notching and instability. A large number of techniques like bone grafting using autograft or allograft, eccentric reaming, augmented base plates, patient-specific instrumentations and custom-made implants are available to tackle bone loss.

MATERIALS AND METHODS

We prospectively collected the data of all patients with glenoid defects undergoing primary or revision reverse shoulder replacement between 2004 and 2017. This included demographic data, ranges of motion, Constant-Murley score and Subjective Shoulder Value (SSV). A pre-operative CT scan was done as well to plan the surgery and calculate the glenoid version. At each follow-up, the clinical function and shoulder scores were assessed. Additionally, the radiographs were assessed for graft incorporation, evidence of lysis and calculation of glenoid version.

RESULTS

Between 2004 and 2017, 37 patients underwent glenoid bone grafting during reverse shoulder arthroplasty. Average age was 72 years (range 46-88). Indications for surgery were cuff tear arthropathy (6 patients); revision of failed other prosthesis (23); primary osteoarthritis (4); rheumatoid arthritis (3); and second-stage revision for infection (1). The glenoid defect was contained in 24 patients, and therefore, impaction graft with a combination of bone graft substitute and/or humeral head autograft was performed. In 13 patients the glenoid defect was severe and uncontainable and therefore a graft-implant composite glenoid was implanted using humeral head autograft or allograft. Average follow-up was 3.6 years (range 1-10). Mean Constant score improved from 34 before surgery to 63 after surgery. Mean SSV score improved from 0.9/10 to 8.3/10. Active movements improved significantly with forward elevation increasing from 54° to 123°; abduction from 48° to 123°; external rotation from 24° to 38°; internal rotation from 57° to 70°. Radiographs at final follow-up showed no radiolucencies around the glenoid component and no evidence of loosening of the implant. In 2 cases there was a grade I notching. There was 100% survivorship at the last follow-up.

CONCLUSION

Impaction bone grafting along with structural grafting when required is an effective and reproducible way of managing severe glenoid bone loss. This technique gives consistent and good clinical and radiological results.

COVID-19 - Changes in Workload and Clinical Practice in Trauma and Orthopaedics in a District General Hospital in the United Kingdom

Introduction:

COVID-19 has had a significant impact on the entire health system. The trauma and orthopaedic service has been compelled to alter working practices to respond proactively and definitively to the crisis. The aim of this study is to summarise the impact of this outbreak on the trauma and orthopaedic workload and outline the response of the department.

Materials and Methods:

We retrospectively collected data comparing patient numbers pre-COVID-19, and prospectively during the early COVID-19 pandemic. We have collected the numbers and nature of outpatient orthopaedic attendances to fracture clinics and elective services, inpatient admissions and the number of fracture neck of femur operations performed.

Results:

The number of outpatient attendances for a musculoskeletal complaint to Accident and Emergency and the number of virtual fracture clinic reviews reduced by almost 50% during COVID-19. The number of face-to-face fracture clinic follow-ups decreased by around 67%, with a five-fold increase in telephone consultations. Inpatient admissions decreased by 33%, but the average number of fracture neck of femur operations performed has increased by 20% during COVID-19 compared to pre-COVID-19 levels.

Conclusion:

We have noted a decrease in some aspects of the trauma and orthopaedic outpatient workload, such as leisure and occupational-related injuries but an increase in others, such as fracture neck of femurs. Many injuries have significantly reduced in numbers and we consider that a model could be developed for treating these injuries away from the acute hospital site entirely, thereby allowing the acute team to focus more appropriate major trauma injuries.

Atypical mycobacterium infection of sternoclavicular joint: A unique case

We report a rare case of atypical Mycobacterium intracellulare infection encountered in a left sternoclavicular joint of an immunocompetent patient. The 34-year-old female patient presented with a one-year history of left sternoclavicular joint pain and swelling. The patient had multiple radiological investigations, which were suspicious for an infective cause. The patient had a biopsy of the joint, which returned showing acid-fast bacilli. The patient consequently received a prolonged course of medical treatment for M. intracellulare.

Synthesis and evaluation of 2,5-furan, 2,5-thiophene and 3,4-thiophene-based derivatives as CXCR4 inhibitors

The interaction between G-Protein coupled receptor CXCR4 and its natural ligand CXCL12 has been linked to inflammation experienced by patients with Irritable Bowel Disease (IBD). Blocking this interaction could potentially reduce inflammatory symptoms in IBD patients. In this work, several thiophene-based and furan-based compounds modeled after AMD3100 and WZ811-two known antagonists that interrupt the CXCR4-CXCL12 interaction-were synthesized and analyzed. Fifteen hit compounds were identified; these compounds exhibited effective concentrations (EC) lower than 1000 nM (AMD3100) and inhibited invasion of metastatic cells by at least 45%. Selected compounds (2d, 2j, 8a) that inhibited metastatic invasion at a higher rate than WZ811 (62%) were submitted for a carrageenan inflammation test, where both 8a and 2j reduced inflammation in the same range as WZ811 (40%) but did not reduce inflammation more than 40%. Select compounds were also modeled in silico to show key residue interactions. These preliminary results with furan-based and thiophene-based analogues contribute to the new class on heterocyclic aromatic-based CXCR4 antagonists.

P4-12-14: Pilot Study Utilizing Fluorine-18 Fluorodeoxyglucose (F-18 FDG) Positron Emission Tomography–Computed Tomography Scan (PET-CT Scan) To Investigate Brain Metabolic Changes during Treatment in Women with Breast Cancer

BACKGROUND: Approximately 25% of the patients undergoing chemotherapy develop cognitive changes. Similarly, significant neurocognitive changes in verbal memory and executive functioning have been reported in patients undergoing endocrine therapy. Though extensively studied, specific changes in the brain associated with cognitive dysfunction are still not clear. We performed an IRB-approved retrospective pilot study utilizing brain images from standard PET-CT scans in patients being treated for breast cancer. Comparison was made between patients initial and follow-up scans to look for metabolic changes.

MATERIALS AND METHODS: Thirty nine patients with a diagnosis of breast cancer were identified from radiology database of West Virginia University Hospitals, who underwent at least two PET-CT scans during their treatment for breast cancer from 2004–2009. Patients with brain metastasis were excluded. NeuroMIM® software analysis program was used to compare a comprehensive database of physiologic brain anatomy and metabolism with F-18 FDG perfusion brain images from the patients. Comparison was made in sixty-three defined brain regions. For each patient, two scans at approximately twelve month intervals were analyzed. The data sets from initial scans were compared with the follow up.

RESULTS: A total of 37 patients received cytotoxic chemotherapy, 2 patients received only endocrine therapy. Data analysis using the signed-rank test shows that the collective Z-score values change between the initial and follow up scans. When data analysis is applied to the individual brain regions, the Lingual Gyrus (p=0.012) and the Angular Gyrus (p=0.056)show statistically significant and near significant decreases in brain metabolism respectively. These regions are attributed with language, mathematics and cognition. Several additional regions such as the fusiform gyrus and the primary visual cortex show p-values between 0.05 and 0.10, which indicate “trending”. These regions may demonstrate statistically significant decrease in metabolism if the sample size is increased.

DISCUSSION: The Lingual and the Angular Gyrus show a statistically significant and near significant decrease in glucose metabolism respectively, in patients receiving treatment for breast cancer. Limitations of this study include lack of baseline brain imaging and its clinical correlation with cognitive function. Based upon these preliminary findings prospective studies are being planned.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P4-12-14.

Role of PET/CT scanning in detecting asymptomatic brain metastases in non-small cell lung cancer

e19038

Background: Up to one-third of non-small cell lung cancer (NSCLC) patients are diagnosed with brain metastasis. Our study aims to evaluate the role of whole body and brain FDG-PET/CT in detecting asymptomatic brain metastasis in this population. Methods: We performed a retrospective chart review of 282 consecutive non-small cell lung cancer patients between February of 2005 and June of 2008. 60 patients with brain metastasis were identified. Information regarding tumor histology and presence of neurological symptoms at the time of discovery of brain metastasis was collected. In addition, data was acquired from brain MRI and PET/CT (with IV contrast) reports including: study date, findings and any change in staging secondary to the study. Results: The median age was 63 years (47 % women). 39 (65%) of the patients had neurological symptoms at the time of discovery of brain metastasis. PET/CT scan with IV contrast was performed in 53 patients with brain metastasis. For patients who had a PET/CT scan, the histological types were: adenocarcinoma (58.4%), unclassified (22.6%), squamous (13.2%), large cell (3.8%) and other (1.8%). PET/CT scan had a sensitivity of 97.8% in detecting CNS metastasis seen on brain MRI. 19/53 patients were found to have asymptomatic brain metastasis on PET/CT scan (2 stage I, 1 stage II, 2 stage III and 13 stage IV). Overall, PET/CT scan resulted in upstaging of 5 asymptomatic and 6 symptomatic patients or 11/53 (20.7%). Conclusions: PET/CT scan with IV contrast has a high sensitivity in detecting brain metastasis in patients with NSCLC when compared to brain MRI. It is effective in detecting asymptomatic brain metastasis in this population. Those patients, who initially were thought to have non-metastatic disease, are spared inappropriate aggressive surgery or radiation.

No significant financial relationships to disclose.

Maximum tolerable dose of cyclophosphamide and azathioprine in Pakistani patients with primary renal disease

OBJECTIVE

The immunosuppressive regimens, at present, mainly rely on western guidelines that were derived from studies conducted in western populations. No such study exists for South Asian population, which is home to almost two billion people different in both genetics and environment from west. Locally derived thresholds for side effects markedly different from western figures may warrant re-adjustment of current local immunosuppressive regimens that are at present based largely on western guidelines. In order to define optimum dose for Cyclophosphamide (CYC) and Azathioprine (AZA) based immunosuppressive therapy, we conducted this study to find out maximum tolerable doses of azathioprine (AZA) and cyclophosphamide (CYC) beyond which neutropenia and thrombocytepenia are most likely to occur in patients with primary renal pathology.

METHOD

Patients with systemic vasculitis and idiopathic glomerulonephritis who were on CYC and AZA were identified through review of medical records at a tertiary care hospital in Pakistan (The Aga Khan University Hospital, Karachi). Patients were categorized under three principal diagnosis i.e. systemic lupus erythematosus (SLE), primary (idiopathic) glomerulonephritis (GN) and Wegener's granulomatosis (WG). The Receiver Operating Curve (ROC) was used to calculate the maximum tolerable dose for both CYC and AZA.

RESULTS

We identified 94 patients aged 6-82 years (median 44.5 years) with primary renal disease (Wegener's granulomatosis n=13, Systemic lupus erythematosis n=62 and idiopathic glomerulonephritis n=19) who received CYC or AZA. Of these 94 patients, 36.2% (n=34) received CYC and 63.8% (n=60) received AZA. The mean dose of CYC was 1.54 +/- 0.50 mg/kg of body weight (range: 0.77-2.93). The mean dose of AZA was 1.64 +/- 0.59 mg/kg of body weight (range: 0.47-2.97). The maximum tolerable doses calculated for CYC and AZA were 1.25 mg/kg and 1.30 mg/kg of body weight respectively. The maximum tolerable dose for CYC and AZA among males could not be calculated, because of insufficient number of patients who developed neutropenia and thrombocytopenia. The maximum tolerable doses for CYC and AZA among females were 1.34 mg/kg and 1.03 mg/kg of body weight respectively. Also we found out that AZA was relatively more likely to cause neutropenia and thrombocytopenia (p=0.07).

CONCLUSION

We thereby recommend that CYC should be initiated at a dose no more than 1 mg/kg of body weight and AZA at an initial dose of 0.75-1.0 mg/kg of body weight. The dose may be adjusted later on the basis of clinical response and laboratory reports.