Field-Based Planetary Protection Operations for Melt Probes: Validation of Clean Access into the Blood Falls, Antarctica, Englacial Ecosystem

Subglacial environments on Earth offer important analogs to Ocean World targets in our solar system. These unique microbial ecosystems remain understudied due to the challenges of access through thick glacial ice (tens to hundreds of meters). Additionally, sub-ice collections must be conducted in a clean manner to ensure sample integrity for downstream microbiological and geochemical analyses. We describe the field-based cleaning of a melt probe that was used to collect brine samples from within a glacier conduit at Blood Falls, Antarctica, for geomicrobiological studies. We used a thermoelectric melting probe called the IceMole that was designed to be minimally invasive in that the logistical requirements in support of drilling operations were small and the probe could be cleaned, even in a remote field setting, so as to minimize potential contamination. In our study, the exterior bioburden on the IceMole was reduced to levels measured in most clean rooms, and below that of the ice surrounding our sampling target. Potential microbial contaminants were identified during the cleaning process; however, very few were detected in the final englacial sample collected with the IceMole and were present in extremely low abundances (∼0.063% of 16S rRNA gene amplicon sequences). This cleaning protocol can help minimize contamination when working in remote field locations, support microbiological sampling of terrestrial subglacial environments using melting probes, and help inform planetary protection challenges for Ocean World analog mission concepts.

Deep Brain Stimulation Lead Localization Variability Comparing Intraoperative MRI Versus Postoperative Computed Tomography

BACKGROUND AND OBJECTIVES

Commercially available lead localization software for deep brain stimulation (DBS) often relies on postoperative computed tomography (CT) scans to define electrode positions. When cases are performed with intraoperative MRI, another imaging set exists with which to perform these localizations. To compare DBS localization error between postoperative CT scans and intraoperative MRI.

METHODS

A retrospective cohort of patients who underwent MRI-guided placement of DBS electrodes using the ClearPoint platform was identified. Using Brainlab Elements, postoperative CT scans were coregistered to intraoperative magnetic resonance images visualizing the ClearPoint guidance sheaths and ceramic stylets. DBS electrodes were identified in CT scans using Brainlab's lead localization tool. Trajectory and vector errors were quantified between scans for each lead in each patient.

RESULTS

Eighty patients with a total of 157 implanted DBS electrodes were included. We observed mean trajectory and vector errors of 0.78 ± 0.44 mm (range 0.1-2.0 mm) and 1.57 ± 0.79 mm (range 0.2-4.2 mm), respectively, between postoperative CT and intraoperative MRI. There were 7 patients with CT scans collected at multiple time points. Trajectory error increased by 0.15 ± 0.42 mm ( P = .31), and vector error increased by 0.22 ± 0.53 mm ( P = .13) in the later scans. Across all scans, there was no significant association between trajectory ( P = .053) or vector ( P = .98) error and the date of CT acquisition. DBS electrodes targeting the subthalamic nucleus had significantly greater trajectory errors ( P = .02) than those targeting the globus pallidus pars internus nucleus.

CONCLUSION

Commercially available software produced largely concordant lead localizations when comparing intraoperative MRIs with postoperative CT scans, with trajectory errors on average <1 mm. CT scans tend to be more comparable with intraoperative MRI in the immediate postoperative period, with increased time intervals associated with a greater magnitude of error between modalities.

Transcranial MR-Guided Focused Ultrasound and Hyperostosis Calvariae Diffusa: Case Report and Systematic Review of the Literature

We describe a 74-year-old male with intractable essential tremor (ET) and hyperostosis calvariae diffusa who was unsuccessfully treated with magnetic resonance-guided focused ultrasound (MRgFUS). A computed tomography performed prior to the procedure demonstrated a skull density ratio (SDR) of 0.37 and tricortical hyperostosis calvariae diffusa. No lesion was evident on post-MRgFUS MRI, and no improvement in the patient's hand tremor was noted clinically. We systematically reviewed the literature to understand outcomes for those patients with hyperostosis who have undergone MRgFUS. A comprehensive literature search using the PubMed, Cochrane, and Google Scholar databases identified 3 ET patients with hyperostosis who failed treatment with MRgFUS. Clinical findings, skull characteristics, treatment parameters, and outcomes were summarized, demonstrating different patterns/degrees of bicortical hyperostosis and variable SDRs (i.e., from 0.38 to ≥0.45). Although we have successfully treated patients with bicortical hyperostosis frontalis interna (n = 50), tricortical hyperostosis calvariae diffusa appears to be a contraindication for MRgFUS despite acceptable SDRs.

Novel approach to analysis of the immune system using an ungated model of immune surface marker abundance to predict health outcomes

Traditionally, the immune system is understood to be divided into discrete cell types that are identified via surface markers. While some cell type distinctions are no doubt discrete, others may in fact vary on a continum, and even within discrete types, differences in surface marker abundance could have functional implications. Here we propose a new way of looking at immune data, which is by looking directly at the values of the surface markers without dividing the cells into different subtypes. To assess the merit of this approach, we compared it with manual gating using cytometry data from the Singapore Longitudinal Aging Study (SLAS) database. We used two different neural networks (one for each method) to predict the presence of several health conditions. We found that the model built using raw surface marker abundance outperformed the manual gating one and we were able to identify some markers that contributed more to the predictions. This study is intended as a brief proof-of-concept and was not designed to predict health outcomes in an applied setting; nonetheless, it demonstrates that alternative methods to understand the structure of immune variation hold substantial progress.

Spinal level and cord involvement in the prediction of sepsis development after vertebral fracture repair for traumatic spinal injury

OBJECTIVE

Despite understanding the associated adverse outcomes, identifying hospitalized patients at risk for sepsis is challenging. The authors aimed to characterize the epidemiology and clinical risk of sepsis in patients who underwent vertebral fracture repair for traumatic spinal injury (TSI).

METHODS

The authors conducted a retrospective cohort analysis of adults undergoing vertebral fracture repair during initial hospitalization after TSI who were registered in the National Trauma Data Bank from 2011 to 2014.

RESULTS

Of the 29,050 eligible patients undergoing vertebral fracture repair, 317 developed sepsis during initial hospitalization. Of these patients, most presented after a motor vehicle accident (63%) or fall (28%). Patients in whom sepsis developed had greater odds of being male (adjusted OR [aOR] 1.5, 95% CI 1.1-1.9), having diabetes mellitus (aOR 1.5, 95% CI 1.11-2.1), and being obese (aOR 1.9, 95% CI 1.4-2.5). Additionally, they had greater odds of presenting with moderate (aOR 2.7, 95% CI 1.8-4.2) or severe (aOR 3.9, 95% CI 2.9-5.2) Glasgow Coma Scale scores and of having concomitant abdominal injuries (aOR 1.9, 95% CI 1.5-2.5) but not cranial, thoracic, or lower-extremity injuries. Interestingly, cervical spine injury was significantly associated with developing sepsis (OR 1.4, 95% CI 1.1-1.8), but thoracic and lumbar spine injuries were not. Spinal cord injury (OR 1.9, 95% CI 1.5-2.5) was also associated with sepsis regardless of level. Patients with sepsis were hospitalized approximately 16 days longer. They had greater odds of being discharged to rehabilitative care or home with rehabilitative care (OR 2.4, 95% CI 1.8-3.2) and greater odds of death or discharge to hospice (OR 6.0, 95% CI 4.4-8.1).

CONCLUSIONS

Among patients undergoing vertebral fracture repair, those with cervical spine fractures, spinal cord injuries, preexisting comorbidities, and severe concomitant injuries are at highest risk for developing postoperative sepsis and experiencing adverse hospital disposition.

Association of venous thromboembolism following pediatric traumatic spinal injuries with injury severity and longer hospital stays

OBJECTIVE

Venous thromboembolism (VTE) can cause significant morbidity and mortality in hospitalized patients, and may disproportionately occur in patients with limited mobility following spinal trauma. The authors aimed to characterize the epidemiology and clinical predictors of VTE in pediatric patients following traumatic spinal injuries (TSIs).

METHODS

The authors conducted a retrospective cohort analysis of children who experienced TSI, including spinal fractures and spinal cord injuries, encoded within the National Trauma Data Bank from 2011 to 2014.

RESULTS

Of the 22,752 pediatric patients with TSI, 192 (0.8%) experienced VTE during initial hospitalization. Proportionally, more patients in the VTE group (77%) than in the non-VTE group (68%) presented following a motor vehicle accident. Patients developing VTE had greater odds of presenting with moderate (adjusted odds ratio [aOR] 2.6, 95% confidence interval [CI] 1.4-4.8) or severe Glasgow Coma Scale scores (aOR 4.3, 95% CI 3.0-6.1), epidural hematoma (aOR 2.8, 95% CI 1.4-5.7), and concomitant abdominal (aOR 2.4, 95% CI 1.8-3.3) and/or lower extremity (aOR 1.5, 95% CI 1.1-2.0) injuries. They also had greater odds of being obese (aOR 2.9, 95% CI 1.6-5.5). Neither cervical, thoracic, nor lumbar spine injuries were significantly associated with VTE. However, involvement of more than one spinal level was predictive of VTE (aOR 1.3, 95% CI 1.0-1.7). Spinal cord injury at any level was also significantly associated with developing VTE (aOR 2.5, 95% CI 1.8-3.5). Patients with VTE stayed in the hospital an adjusted average of 19 days longer than non-VTE patients. They also had greater odds of discharge to a rehabilitative facility or home with rehabilitative services (aOR 2.6, 95% CI 1.8-3.6).

CONCLUSIONS

VTE occurs in a low percentage of hospitalized pediatric patients with TSI. Injury severity is broadly associated with increased odds of developing VTE; specific risk factors include concomitant injuries such as cranial epidural hematoma, spinal cord injury, and lower extremity injury. Patients with VTE also require hospital-based and rehabilitative care at greater rates than other patients with TSI.

Perceptions of heat-health impacts and the effects of knowledge and preventive actions by outdoor workers in Hanoi, Vietnam

Extreme heat is an increasing climate threat, most pronounced in urban areas where poor populations are at particular risk. We analyzed heat impacts and vulnerabilities of 1027 outdoor workers who participated in a KAP survey in Hanoi, Vietnam in 2018, and the influence of their mitigation actions, their knowledge of heat-risks, and access to early warnings. We grouped respondents by their main income (vendors, builders, shippers, others, multiple jobs, and non-working) and analyzed their reported heat-health impacts, taking into consideration socioeconomics, knowledge of heat impacts and preventive measures, actions taken, access to air-conditioning, drinking amounts and use of weather forecasts. We applied linear and logistic regression analyses using R. Construction workers were younger and had less knowledge of heat-health impacts, but also reported fewer symptoms. Older females were more likely to report symptoms and visit a doctor. Access to air-conditioning in the bedroom depended on age and house ownership, but did not influence heat impacts as cooling was too expensive. Respondents who knew more heat exhaustion symptoms were more likely to report impacts (p < 0.01) or consult a doctor (p < 0.05). Similarly, those who checked weather updates were more likely to report heat impacts (p < 0.01) and experienced about 0.6 more symptoms (p < 0.01). Even though occupation type did not explain heat illness, builders knew considerably less (40%; p < 0.05) about heat than other groups but were twice as likely to consult a doctor than street vendors (p < 0.01). Knowledge of preventive actions and taking these actions both correlated positively with reporting of heat-health symptoms, while drinking water did not reduce these symptoms (p < 0.01). Child carers and homeowners experienced income losses in heatwaves (p < 0.01). The differences support directed actions, such as dissemination of educational materials and weather forecasts for construction workers. The Red Cross assisted all groups with cooling tents, provision of drinks and health advice.

Posterior Cerebral Artery Aneurysm Re-Rupture Following Revascularization for Moyamoya Disease

OBJECTIVES

Aneurysms associated with hemorrhagic moyamoya disease (MMD) are reported to stabilize or recede following revascularization.

CASE REPORT/RESULTS

A 29 year-old male with no past medical history presented obtunded with diffuse intraventricular hemorrhage and vascular imaging demonstrating bilateral MMD without any associated aneurysms. He underwent a delayed right-sided STA-MCA bypass and pial synangiosis, and was subsequently discharged on hospital day 24 with a modified Rankin Scale score (mRS) of 2. He returned eleven days later from a rehabilitation facility with recurrent IVH. A saccular 5 mm right P4 segment posterior cerebral artery aneurysm was seen on a diagnostic angiogram and embolized with Onyx glue.

CONCLUSIONS

Distal posterior circulation artery aneurysmal rupture is a rare cause of hemorrhagic MMD. This case demonstrates the capacity of these aneurysms to re-rupture following revascularization and underscores the importance of treating the aneurysms directly.

The diagnosis and management of primary and iatrogenic soft tissue sarcomas of the sella

PURPOSE

Soft tissue sarcoma (STS) of the sella is exceptionally rare. We conducted a case series, literature review, and nationwide analysis of primary and iatrogenic (radiation-associated) STS of the sella to define the clinical course of this entity.

METHODS

This study employed a multi-institutional retrospective case review, literature review, and nationwide analysis using the National Cancer Database (NCDB).

RESULTS

We report five patients who were diagnosed at three institutions with malignant STS of the sella. All patients presented with symptoms related to mass effect in the sellar region. All tumors extended to the suprasellar space, with the majority displaying extension into the cavernous sinus. All patients underwent an operation via a transsphenoidal approach with a goal of maximal safe tumor resection in four patients and biopsy for 1 patient. Histopathologic evaluation demonstrated STS in all patients. Post-operative adjuvant radiotherapy and chemotherapy were given to 2 and 1 out of 4 patients with known post-operative clinical course, respectively. The 1-year and 5-year overall survival rates were 100% (5/5) and 25% (1/4). Twenty-two additional reports of primary, non-iatrogenic STS of the sella were identified in the literature. Including the three cases from our series, treatment included resection in all cases, and adjuvant radiotherapy and chemotherapy were utilized in 50% (12/24) and 17% (4/24) of cases, respectively. The national prevalence of malignant STS is estimated to be 0.01% among all pituitary and sellar tumors within the NCDB.

CONCLUSIONS

We report the prevalence and survival rates of STS of the sella. Multimodal therapy, including maximal safe resection, chemotherapy, and radiotherapy are necessary to optimize outcomes for this uncommon pathology.

Intraventricular metastatic melanoma: A case report and review of the literature

Intraventricular melanoma is a very rare and highly malignant disease. Safe resection is the mainstay of treatment, but no standard guidelines exist for adjuvant therapy. Early histologic and molecular diagnosis is key for improved survival.

Impact of insurance on hospital course and readmission after resection of benign meningioma

INTRODUCTION

Surgical outcomes and healthcare utilization have been shown to vary based on patient insurance status. We analyzed whether patients' insurance affects case urgency for and readmission after craniotomy for meningioma resection, using benign meningioma as a model system to minimize confounding from the disease-related characteristics of other neurosurgical pathologies.

METHODS

We analyzed 90-day readmission for patients who underwent resection of a benign meningioma in the Nationwide Readmission Database from 2014-2015.

RESULTS

A total of 9783 meningioma patients with private insurance (46%), Medicare (39%), Medicaid (10%), self-pay (2%), or another scheme (3%) were analyzed. 72% of all cases were elective; with 78% of cases in privately insured patients being elective compared to 71% of Medicare (p > 0.05), 59% of Medicaid patients (OR 2.3, p < 0.001), and 49% of self-pay patients (OR 3.4, p < 0.001). Medicare (OR 1.5, p = 0.002) and Medicaid (OR 1.4, p = 0.035) were both associated with higher likelihood of 90-day readmission compared to private insurance. In comparison, 30-day analyses did not unveil this discrepancy between Medicaid and privately insured, highlighting the merit for longer-term outcomes analyses in value-based care. Patients readmitted within 30 days versus those with later readmissions possessed different characteristics.

CONCLUSIONS

Compared to patients with private insurance coverage, Medicaid and self-pay patients were significantly more likely to undergo non-elective resection of benign meningioma. Medicaid and Medicare insurance were associated with a higher likelihood of 90-day readmission; only Medicare was significant at 30 days. Both 30 and 90-day outcomes merit consideration given differences in readmitted populations.

Surveillance imaging with FDG-PET/CT in the post-operative follow-up of stage 3 melanoma

Background

As early detection of recurrent melanoma maximizes treatment options, patients usually undergo post-operative imaging surveillance, increasingly with FDG-PET/CT (PET). To assess this, we evaluated stage 3 melanoma patients who underwent prospectively applied and sub-stage-specific schedules of PET surveillance.

Patients and methods

From 2009, patients with stage 3 melanoma routinely underwent PET +/- MRI brain scans via defined schedules based on sub-stage-specific relapse probabilities. Data were collected regarding patient characteristics and outcomes. Contingency analyses were carried out of imaging outcomes.

Results

One hundred and seventy patients (stage 3A: 34; 3B: 93; 3C: 43) underwent radiological surveillance. Relapses were identified in 65 (38%) patients, of which 45 (69%) were asymptomatic. False-positive imaging findings occurred in 7%, and 6% had treatable second (non-melanoma) malignancies. Positive predictive values (PPV) of individual scans were 56%-83%. Negative scans had predictive values of 89%-96% for true non-recurrence [negative predictive values (NPV)] until the next scan. A negative PET at 18 months had NPVs of 80%-84% for true non-recurrence at any time in the 47-month (median) follow-up period. Sensitivity and specificity of the overall approach of sub-stage-specific PET surveillance were 70% and 87%, respectively. Of relapsed patients, 33 (52%) underwent potentially curative resection and 10 (16%) remained disease-free after 24 months (median).

Conclusions

Application of sub-stage-specific PET in stage 3 melanoma enables asymptomatic detection of most recurrences, has high NPVs that may provide patient reassurance, and is associated with a high rate of detection of resectable and potentially curable disease at relapse.

Predicting nonroutine discharge after elective spine surgery: external validation of machine learning algorithms

OBJECTIVE

Nonroutine discharge after elective spine surgery increases healthcare costs, negatively impacts patient satisfaction, and exposes patients to additional hospital-acquired complications. Therefore, prediction of nonroutine discharge in this population may improve clinical management. The authors previously developed a machine learning algorithm from national data that predicts risk of nonhome discharge for patients undergoing surgery for lumbar disc disorders. In this paper the authors externally validate their algorithm in an independent institutional population of neurosurgical spine patients.

METHODS

Medical records from elective inpatient surgery for lumbar disc herniation or degeneration in the Transitional Care Program at Brigham and Women's Hospital (2013-2015) were retrospectively reviewed. Variables included age, sex, BMI, American Society of Anesthesiologists (ASA) class, preoperative functional status, number of fusion levels, comorbidities, preoperative laboratory values, and discharge disposition. Nonroutine discharge was defined as postoperative discharge to any setting other than home. The discrimination (c-statistic), calibration, and positive and negative predictive values (PPVs and NPVs) of the algorithm were assessed in the institutional sample.

RESULTS

Overall, 144 patients underwent elective inpatient surgery for lumbar disc disorders with a nonroutine discharge rate of 6.9% (n = 10). The median patient age was 50 years and 45.1% of patients were female. Most patients were ASA class II (66.0%), had 1 or 2 levels fused (80.6%), and had no diabetes (91.7%). The median hematocrit level was 41.2%. The neural network algorithm generalized well to the institutional data, with a c-statistic (area under the receiver operating characteristic curve) of 0.89, calibration slope of 1.09, and calibration intercept of -0.08. At a threshold of 0.25, the PPV was 0.50 and the NPV was 0.97.

CONCLUSIONS

This institutional external validation of a previously developed machine learning algorithm suggests a reliable method for identifying patients with lumbar disc disorder at risk for nonroutine discharge. Performance in the institutional cohort was comparable to performance in the derivation cohort and represents an improved predictive value over clinician intuition. This finding substantiates initial use of this algorithm in clinical practice. This tool may be used by multidisciplinary teams of case managers and spine surgeons to strategically invest additional time and resources into postoperative plans for this population.

Oncolytic viruses: overcoming translational challenges

Oncolytic virotherapy (OVT) is a promising approach in which WT or engineered viruses selectively replicate and destroy tumor cells while sparing normal ones. In the last two decades, different oncolytic viruses (OVs) have been modified and tested in a number of preclinical studies, some of which have led to clinical trials in cancer patients. These clinical trials have revealed several critical limitations with regard to viral delivery, spread, resistance, and antiviral immunity. Here, we focus on promising research strategies that have been developed to overcome the aforementioned obstacles. Such strategies include engineering OVs to target a broad spectrum of tumor cells while evading the immune system, developing unique delivery mechanisms, combining other immunotherapeutic agents with OVT, and using clinically translatable mouse tumor models to potentially translate OVT more readily into clinical settings.

Does suturing tonsil pillars post-tonsillectomy reduce postoperative hemorrhage?: A literature review

OBJECTIVE

Literature review comparing post-tonsillectomy hemorrhage in pediatric and adult patients with and without suturing tonsil pillars to investigate whether suturing tonsil pillars reduces the risk of post-tonsillectomy hemorrhage.

REVIEW METHODS

Online journal databases were searched using the key phrases "post tonsillectomy hemorrhage", "post tonsillectomy bleed", and "tonsil pillar suture". 10 published studies were found regarding tonsil pillar suturing, four directly related to postoperative bleeding and five focusing on postoperative pain reduction. There was one study that evaluated both pain and bleeding. The pain reduction studies were comprised of 225 patients while the postoperative bleeding studies included 3987 patients.

CONCLUSIONS

Suturing tonsil pillars after tonsillectomy may be beneficial after cold tonsillectomy.

IMPLICATIONS FOR PRACTICE

Post-operative bleeding is one of the most common complications that can result in increased patient distress and hospitalization. In this article, we provide a literature review of tonsil pillar suturing and post-tonsillectomy hemorrhage. Our study suggests suturing the tonsil pillars immediately post-tonsillectomy may reduce the risk of severe post-operative bleeding requiring return to the operating room for certain patients.

Experience and Impact of a Locally-Based Peer, Volunteer Cancer Support Programme in Hospital Melaka, Melaka Malaysia

Background: Melaka is a small southern state in Peninsular Malaysia. On average, the state has an annual incidence of 200 odd breast cancer patients, largely treated out of its public, subsidized, single tertiary treatment center of Hospital Melaka. Hospital Melaka is an 800-bedded hospital with multiple specialties including surgery and radiology. Though the hospital does not have a dedicated oncology department, cancer treatment is carried out via phone consultations and visiting oncologists as well as a team of on-site nursing staff who are trained to initiate and monitor treatment. Feedback from Hospital Melaka staff highlighted that there was a drop-out rate of about 30% of patients from the treatment journey. Qualitative interviews with different stakeholders including patient revealed that the drop-out may be driven by factors such as: i) fear of surgery, ii) fear of chemotherapy, iii) fear of disfigurement, iv) loss of spouse v) emotional distress and shock; and vi) delay in waiting times for different levels of diagnostics and treatment. Aim: The aim of the initiative was to reduce the rate of patients who defaulted out from the cancer treatment journey via a three-pronged approach: a) improving understanding about cancer and treatment by patients and family members; b) integrating peer-support into the clinical treatment pathway at the hospital and reduction of waiting times; and c) maintaining a continuous interaction with the patient throughout the treatment journey. Methods: The inception and deployment of a locally-based peer, volunteer support program for breast cancer patients and families as part of the formal cancer treatment process in Hospital Melaka. Volunteers were consisted of a trained mix of cancer survivors, current and retired healthcare practitioners and provided information pertaining to treatment and care aspects of breast cancer as well as emotional support and follow-up of patients via phone or in person to ensure compliance to treatment. In this study, we engaged with various stakeholders including hospital management and clinicians. Then, support group's services were formalized into the care pathway for all patients with breast cancer; with both volunteers able to send and receive patient referrals. Results: Statistically significant reductions in patient delays in decision-making to seek treatment as well as a significant decrease of 12.5% in the number of defaulters. Conclusion: A support program built with support from all stakeholders and run by volunteers and embedded within the formal care process acts as a catalyst to enhance both service delivery as well as keeping patients engaged on the cancer care journey.

Comparative Analysis of Non-viral Transfection Methods in Mouse Embryonic Fibroblast Cells

Mouse embryonic fibroblast (MEF) cells are an important in vitro model for developmental biology, disease, and reprogramming studies. However, as with other primary cells, they are challenging to transfect. Although viral gene-delivery methods achieve high gene-delivery efficiency, challenges with cell mutagenesis and safety among others have led to the use and improvement of non-viral gene-delivery methods in MEF cells. Despite the importance of gene delivery in MEF cells, there is limited comparison of method/reagent efficacy. In this study, we compared the effectiveness of different gene-delivery methods and several reagents currently available in MEF cells by introducing a plasmid containing enhanced green fluorescent protein (EGFP). We analyze transfection efficiency by EGFP fluorescence. Our results suggest that two gene-delivery methods-electroporation and magnetofection in combination with a lipid reagent, are the most efficient transfection methods in MEF cells. This study provides a foundation for the selection of transfection methods or reagents when using MEF cells.

MSC-seeded dense collagen scaffolds with a bolus dose of VEGF promote healing of large bone defects

The functional repair of large skeletal defects remains a significant challenge to orthopaedic surgeons due to the lack of effective strategies to promote bone regeneration, particularly in the elderly. This study investigated the potential use of bone marrow derived mesenchymal stromal cells (MSC) in a dense collagen scaffold with a bolus dose of vascular endothelial growth factor (VEGF) to repair a defect in the femoral diaphysis of mice. MSC isolated from bone marrow of 4-month-old donor mice were seeded in type I collagen gels that were then compressed to form scaffolds with a fibrillar density similar to osteoid. The cells remained metabolically active in scaffolds incubated in vitro for up to 15 days and differentiated into osteoblasts that deposited calcium-phosphate mineral into the scaffold, which was quantified using micro-computed tomographic (micro-CT) imaging. When implanted in a 1 mm x 3 mm unicortical defect the MSC-loaded scaffolds were rapidly mineralised and integrated into host bone with administration of 10 ng of recombinant VEGF injected into the femoral canal at 4 days postoperative. Empty scaffolds and MSC-seeded scaffolds implanted in defects that did not receive a bolus dose of VEGF did not mineralise or integrate with native bone. The approach with MSC, hydrogels and a biologic factor already approved for human use warrants further pre-clinical investigation with a large animal model.

Volaemic assessment of the elderly hyponatraemic patient: reliability of clinical assessment and validation of bioelectrical impedance analysis

BACKGROUND

Hyponatraemia is the commonest electrolyte disturbance of hospital inpatients. Assessment of volaemic status is an important part of diagnosis and management.

AIM

To determine reliability of clinical assessment of volaemic state by assessing inter-observer variability of clinical measures of volaemic state. To assess validity of bioelectrical impedance analysis as a tool to measure total body water in elderly hyponatraemic patients.

DESIGN

Observational study conducted in a Department of Medicine for the Elderly.

METHODS

Hospital inpatients >65 years old (n=22) with serum sodium concentration <130 mmol/l were included. Two assessors determined volaemic state on two occasions 72 h apart. Level of agreement between observers was determined on each occasion. Total body water estimation was undertaken with bioelectrical impedance analysis and measurement of dilution of deuterium oxide. Correlation between these two measures was then analysed.

RESULTS

Cohen's κ for agreement between two observers for overall assessment of volaemic state was 0.59 (P<0.01). Values for agreement between individual clinical markers of volaemic state ranged between 0.16 and 0.45. Pearson correlation coefficient (r) for correlation between estimation of total body water undertaken by bioelectrical impedance analysis and by measurement of dilution of deuterium oxide was 0.69 (P<0.001).

CONCLUSION

There was moderate inter-observer agreement of overall clinical volaemic assessment of elderly hyponatraemic patients. Total body water estimation by bioelectrical impedance analysis correlates well with estimation by measurement of dilution of deuterium oxide, providing a potentially useful tool to improve the management of the elderly hyponatraemic patient.

Identification of prognostically-relevant signature genes differentially expressed between primary colorectal carcinoma and hepatic metastasis

4116

Background: Colorectal cancer (CRC) is the third most common cancer in the US. Hepatic metastasis (HM), the most common distant metastasis from CRC and occurring in about 60% of CRC patients during the course of their treatment, is a significant clinical problem. Although several clinical prognostic factors for HM from CRC have been identified, little is known about its molecular aspect. Methods: Under IRB approved protocols, we profiled gene expression in a set of 30 specimens from primary CRC and 31 unmatched specimens of HM from CRC. To survey the molecular variations between the two groups, we used cDNA microarrays containing ∼22,000 human genes, and identified differentially expressed genes using the Significance Analysis of Microarrays (SAM) method. To further characterize the clinical relevance of differentially expressed genes, we used immunohistochemistry (IHC) on tissue microarrays of tumor tissues obtained from an independent dataset of 154 patients with primary CRC. Results: Supervised analysis using SAM identified >200 genes with significantly higher expression in HM from CRC compared to primary CRC (and also compared to normal liver), with a false discovery rate (FDR) of <1%. IHC staining of two highly ranked differentially expressed signature genes, SPP1 (osteopontin) and LEF1 (lymphoid enhancer factor-1; a transcriptional mediator of Wnt pathway activation), showed protein overexpression (OE) in 60% and 44% of CRC cases, respectively; with a significant correlation with liver involvement in LEF1 expression (chi-square p=0.04) vs. SPP1 OE (p=0.14). Kaplan Meier analysis revealed significantly worsening survival in patients with LEF1 OE (p<0.01), but not SPP1 (p=0.14). Multivariate analysis identified several relevant prognostic markers: stage (p<0.001), nodal status (p <0.01) and LEF1 OE (p=0.02). Conclusions: Among signature genes differentially expressed between CRC and HM, we demonstrate LEF1, not SPP1, OE to be a poor prognostic factor for survival. Further studies are needed to characterize other signature genes, and to refine our understanding of the role of altered LEF1 expression in CRC tumorigenesis.

No significant financial relationships to disclose.

Endosome fusion in living cells overexpressing GFP-rab5

CHO and BHK cells which overexpress either wild-type rab5 or rab5:Q79L, a constitutively active rab5 mutant, develop enlarged cytoplasmic vesicles that exhibit many characteristics of early endosomes including immunoreactivity for rab5 and transferrin receptor. Time-lapse video microscopy shows the enlarged endosomes arise primarily by fusion of smaller vesicles. These fusion events occur mostly by a ‘bridge’ fusion mechanism in which the initial opening between vesicles does not expand; instead, membrane flows slowly and continuously from the smaller to the larger endosome in the fusing pair, through a narrow, barely perceptible membranous ‘bridge’ between them. The unique aspect of rab5 mediated ‘bridge’ fusion is the persistence of a tight constriction at the site where vesicles merge and we hypothesize that this constriction results from the relatively slow disassembly of a putative docking/fusion complex. To determine the relation of rab5 to the fusion ‘bridge’, we used confocal fluorescence microscopy to monitor endosome fusion in cells overexpressing GFP-rab5 fusion proteins. Vesicle docking in these cells is accompanied by recruitment of the GFP-rab5 into a brightly fluorescent spot in the ‘bridge’ region between fusing vesicles that persists throughout the entire length of the fusion event and which often persist for minutes following endosome fusion. Other endosomal membrane markers, including FM4-64, are not concentrated in fusion ‘bridges’. These results support the idea that the GFP-rab5 spots represent the localized accumulation of GFP-rab5 between fusing endosomes and not simply overlap of adjacent membranes. The idea that the GFP-rab5 spots do not represent membrane overlap is further supported by experiments using photobleaching techniques and confocal imaging which show that GFP-rab5 localized in spots between fusion couplets is resistant to diffusion while GFP-rab5 on endosomal membranes away from these spots rapidly diffuses with a rate constant of about 1.0 (+/-0.3) x10(-)(9)cm(2)/second.

Genetic and physiologic analysis of the role of uncoupling protein 3 in human energy homeostasis

By virtue of its potential effects on rates of energy expenditure, uncoupling protein 3 (UCP3) is an obesity candidate gene. We identified nine sequence variants in UCP3, including Val9Met, Val102Ile, Arg282Cys, and a splice site mutation in the intron between exons 6 and 7. The splice mutation results in an inability to synthesize mRNA for the long isoform (UCP3L) of UCP3. Linkage (sib pair), association, and transmission disequilibrium testing studies on 942 African-Americans did not suggest a significant effect of UCP3 on body composition in this group. In vastus lateralis skeletal muscle of individuals homozygous for the splice mutation, no UCP3L mRNA was detectable; the short isoform (UCP3S) was present in an increased amount. In this muscle, we detected no alterations of in vitro mitochondrial coupling activity, mitochondrial respiratory enzyme activity, or systemic oxygen consumption or respiratory quotient at rest or during exercise. These genetic and physiologic data suggest the following possibilities: UCP3S has uncoupling capabilities equivalent to UCP3L; other UCPs may compensate for a deficiency of bioactive UCP3L; UCP3L does not function primarily as a mitochondrial uncoupling protein.

Heterozygosity for Lep(ob) or Lep(rdb) affects body composition and leptin homeostasis in adult mice

In an effort to understand the genetics of human obesity, we have studied the physiology and molecular genetics of rodent models with monogenetic forms of obesity including the leptin gene-defective (Lep(ob)/Lep(ob)) and leptin receptor gene-defective (Lep(rdb)/Lep(rdb)) mouse. In the experiments reported here, we investigated the effects of heterozygosity at Lep(ob) and Lep(rdb) on body composition and circulating leptin concentration in +/+, Lep(rdb)/+, and Lep(ob)/+ adult mice to identify possible gene dosage effects of these mutations that might elucidate their physiology. Adult mice heterozygous for the Lep(ob) or Lep(rdb) allele had equivalent fat mass and percentage body fat, which was increased 27-47% and 23-35%, respectively, relative to +/+ littermates. Plasma leptin concentrations adjusted for fat mass were 6.5 ng/ml in the Lep(ob)/+, 9.6 ng/ml in the +/+, and 11.5 ng/ml in the Lep(rdb)/+ mice. Sex had no effect on plasma leptin after controlling for fat mass. These data, and data from a small number of mice heterozygous at both Lep(ob) and Lep(rdb) (compound heterozygotes), suggest that leptin protein produced per mass of body fat is reduced in Lep(ob)/+ mice and that body fat is increased in Lep(ob)/+ mice until plasma leptin concentrations reach that of a normal +/+ mouse. The elevated plasma leptin concentration in the Lep(rdb)/+ mice suggests that LEPR may mediate autocrine suppression of Lep expression. These results raise the possibility that human mutations that have even subtle effects on the leptin/leptin receptor system in either the homozygous or heterozygous state may have significant effects on adiposity.

Genetic modifiers of Leprfa associated with variability in insulin production and susceptibility to NIDDM

In an attempt to identify the genetic basis for susceptibility to non-insulin-dependent diabetes mellitus within the context of obesity, we generated 401 genetically obese Leprfa/Leprfa F2 WKY13M intercross rats that demonstrated wide variation in multiple phenotypic measures related to diabetes, including plasma glucose concentration, percentage of glycosylated hemoglobin, plasma insulin concentration, and pancreatic islet morphology. Using selective genotyping genome scanning approaches, we have identified three quantitative trait loci (QTLs) on Chr. 1 (LOD 7.1 for pancreatic morpholology), Chr. 12 (LOD 5.1 for body mass index and LOD 3.4 for plasma glucose concentration), and Chr. 16 (P < 0.001 for genotype effect on plasma glucose concentration). The obese F2 progeny demonstrated sexual dimorphism for these traits, with increased diabetes susceptibility in the males appearing at approximately 6 weeks of age, as sexual maturation occurred. For each of the QTLs, the linked phenotypes demonstrated sexual dimorphism (more severe affection in males). The QTL on Chr. 1 maps to a region vicinal to that previously linked to adiposity in studies of diabetes susceptibility in the nonobese Goto-Kakizaki rat, which is genetically closely related to the Wistar counterstrain we employed. Several candidate genes, including tubby (tub), multigenic obesity 1 (Mob1), adult obesity and diabetes (Ad), and insulin-like growth factor-2 (Igf2), map to murine regions homologous to the QTL region identified on rat Chr. 1.

Tension distribution of single motor units in multitendoned muscles: comparison of a homologous digit muscle in cats and monkeys

To determine whether single motor units (MUs) in multitendoned muscles distribute tension to multiple tendons or instead focus tension selectively on a single tendon, we examined the distribution of tension generated by single MUs in the cat extensor digitorum lateralis (EDLat), and in its macaque homolog, the extensor digiti quarti et quinti (ED45). General properties of MUs (maximal tetanic tension, axonal conduction velocity, and twitch rise time) were similar in these muscles to those reported for other limb muscles in cats and monkeys. Most cat EDLat MUs were found to exert tension rather selectively on one of the three tendons of the muscle. Fast fatigable MUs were slightly but significantly more selective than fast fatigue-resistant and slow MUs. In contrast, and contrary to expectation, the macaque ED45 contained a lower proportion of MUs that exerted tension selectively on one of the two tendons of the muscle, and a higher proportion of relatively nonselective MUs. These findings suggest that the cat EDLat may consist of three functional subdivisions, each acting preferentially on a different tendon, whereas the macaque ED45 is more likely to function as a single multitendoned muscle.

Genomic structure of the human OB receptor and identification of two novel intronic microsatellites

Identification of the OB (leptin) receptor (OBR) as the gene that is defective in diabetes (Leprdb) mice and fatty (Leprfa) rats provides an important candidate gene for the study of the genetics of human obesity. We defined the boundaries of the 18 coding exons for the long form of OBR, and sequenced the immediately adjacent intronic regions. These sequences can be used to generate reagents for genetic analysis (e.g., direct sequencing, single-stranded conformational polymorphism analysis, etc.) of the possible role of OBR in the regulation of adiposity in humans. In addition, we have identified two highly polymorphic intronic microsatellites that can be scored with the polymerase chain reaction.