Machine Learning in Neurosurgery: Toward Complex Inputs, Actionable Predictions, and Generalizable Translations.

Machine learning can predict neurosurgical diagnosis and outcomes, power imaging analysis, and perform robotic navigation and tumor labeling. State-of-the-art models can reconstruct and generate images, predict surgical events from video, and assist in intraoperative decision-making. In this review, we will detail the neurosurgical applications of machine learning, ranging from simple to advanced models, and their potential to transform patient care. As machine learning techniques, outputs, and methods become increasingly complex, their performance is often more impactful yet increasingly difficult to evaluate. We aim to introduce these advancements to the neurosurgical audience while suggesting major potential roadblocks to their safe and effective translation. Unlike the previous generation of machine learning in neurosurgery, the safe translation of recent advancements will be contingent on neurosurgeons' involvement in model development and validation.

Systemic consequences of abnormal cholesterol handling: Interdependent pathways of inflammation and dyslipidemia.

Metabolic conditions such as obesity and associated comorbidities are increasing in prevalence worldwide. In chronically inflamed pathologies, metabolic conditions are linked to early onset cardiovascular disease, which remains the leading cause of death despite decades of research. In recent years, studies focused on the interdependent pathways connecting metabolism and the immune response have highlighted that dysregulated cholesterol trafficking instigates an overactive, systemic inflammatory response, thereby perpetuating early development of cardiovascular disease. In this review, we will discuss the overlapping pathways connecting cholesterol trafficking with innate immunity and present evidence that cholesterol accumulation in the bone marrow may drive systemic inflammation in chronically inflamed pathologies. Lastly, we will review the current therapeutic strategies that target both inflammation and cholesterol transport, and how biologic therapy restores lipoprotein function and mitigates the immune response.

Online Focus Groups with Parents And Adolescents with Heart Transplants: Challenges and Opportunities.

Pediatric heart transplant recipients are scarce and widely dispersed. Previous studies of adolescents in this population were limited to small homogenous samples. Although online focus groups are an emerging data collection method, its use in pediatric populations has not been fully realized. The purpose of this study was to explore the feasibility of using online focus groups with pediatric populations. Adolescents (aged 13 to 21 years) at least 6 months post-heart transplant and their parents were recruited from two children's hospitals. An online discussion forum (iTracks) was used to conduct asynchronous focus groups with separate parent and adolescent groups. Six parents and four adolescents participated in the discussions. iTracks provided a framework for conducting focus groups in dispersed populations. Access to the discussion transcripts enhanced data analysis and eliminated transcription costs. Overall, online discussion forums were a feasible and cost-effective option to conduct online focus groups in this pediatric population.

Thermochemical properties of cellulose acetate blends with acetosolv and sawdust lignin: A comparative study.

Sawdust (SD) and cotton-lignin blends (CLB) were acetylated and the effect of lignin type and content on thermoplastic properties of the acetate produced was studied. The lignin in samples did not significantly affect the degree of acetylation. An increase in acetyl groups of 1-3% was observed in acetylated SD (ASD) unlike acetylated CLB (ACLB). Thermogravimetric analysis showed two thermal degradation zones; one at 190-200°C and the other at 330-370°C. The early degradation in ASD corresponds to galactoglucomannans while that in ACLB corresponds to the low-molecular-weight lignin. The second degradation is due to decomposition of cellulose acetate and high-molecular-weight lignin. DSC analysis showed homogeneous behaviour in ASD with only one glass transition temperature (Tg) at 170-180°C, unlike ACLB that showed two Tgs at 170-180°C. Sawdust acetylation, taking advantage of its residual lignin, showed higher reactivity and miscibility as compared to the same material produced by adding previously extracted lignin on cotton.

Outcomes in highly sensitized pediatric heart transplant patients using current management strategies.

BACKGROUND: Previous studies have suggested that children with pre-formed anti-HLA antibodies (PRA) undergoing orthotopic heart transplantation (OHT) have increased risk for rejection, coronary artery vasculopathy (CAV) and death. In 2005, our program started utilizing aggressive desensitization (including plasmapheresis, IVIg, pulse cytoxan and rituximab) with the goal of improving outcomes for these patients. The purpose of this study was to compare outcomes with this new strategy in recipients with pre-OHT high PRA (>10%) vs low PRA ≤10%). METHODS: A retrospective study of 70 consecutive pediatric OHT patients was undertaken between January 2005 and July 2013 to identify patients with pre-OHT PRA >10% (high PRA), or PRA ≤10% (low PRA). Demographic/data information and detailed post-OHT outcomes, including rejection, 30-day and overall mortality, freedom from significant rejection, and CAV, were analyzed. RESULTS: Fourteen (20%) patients had high PRA and 56 (80%) did not. There was a significant decrease in PRA values before and after desensitization. Thirty-day and overall mortality and the proportion of patients with rejections or CAV were lower in the high PRA group, although the difference was not statistically significant. Kaplan-Meier survival analysis revealed no significant difference in survival between the two groups. There was a significant difference in survival in our sensitized patients before 2005 vs after 2005. CONCLUSIONS: We identified no significant differences in outcomes between high or low PRA patients. These preliminary findings may suggest improvement in OHT outcomes for high PRA patients as a result of aggressive desensitization. A larger study is warranted to confirm these findings.

Acetylation of bleached Kraft pulp: effect of xylan content on properties of acetylated compounds.

Bleached Kraft pulp (BKP) from Eucalyptus globulus and cotton xylan blends (CXB) was acetylated. The effects of xylan content on cellulose acetylation and the properties of the acetylated material were studied. An increase in xylan content caused a slight decrease in the degree of substitution (2.98 to 2.68 for CXB; 2.93 to 2.84 for BKP). Thermal analysis showed that the melting temperature also decreases from 268.0 to 188.8 °C for CXB and from 221.4 to 212.8 °C for BKP. Moreover, the solubility decreased due to the partial dissolution of acetylated xylans. The presence of xylans during Kraft pulp acetylation does not have a significant negative effect on the physical properties of the acetylated material, but the decrease in melting temperature was beneficial for the application of acetylated polymer as a natural internal plasticizer. This is considered to be an important argument for BKP utilization in the cellulose acetate manufacturing process.

Transition to self-management after pediatric heart transplant.

CONTEXT: Little is known about adolescent transition to self-management after heart transplant. This gap in knowledge is critically important because the consequences of poor self-management are costly and life-threatening, often resulting in nonadherence, rejection, repeated hospitalizations, and poor quality of life. OBJECTIVE: To explore how adolescents and parents perceive their roles in self-management, and how adolescents integrate self-management into their daily lives and navigate the transition from parent-dominated to self-management. DESIGN: Qualitative descriptive design, using online focus groups. SETTING: Online focus groups using itracks, an online qualitative software program. PARTICIPANTS: A purposive sample of 4 adolescents, 13 to 21 years old, who were at least 6 months posttransplant, and of 6 parents of adolescent heart transplant recipients. RESULTS: Several parallel themes emerged from the parent and adolescent online focus groups. Managing medications was the predominant theme for both parents and adolescents. For the remaining themes, parents and adolescents expressed similar ideas that were categorized into parallel themes, which included staying on top of things/becoming independent, letting them be normal/being normal, and worries and stressors. CONCLUSIONS: The transition to self-management after heart transplant was a clear goal for both parents and adolescents. The transition is a shared responsibility between parents and adolescents with a gradual shift from parent-directed to self-management. The process of transition was not linear or smooth, and in several instances, parents described efforts to transfer responsibility to the adolescent only to take it back when complications arose. Additional research with a larger sample is needed in order to fully understand adolescent heart transplant recipients' transition to self-management.

Chromatographic approaches for determination of low-molecular mass aldehydes in bio-oil.

HPLC-UV and GC/MS determination of aldehydes in bio-oil were evaluated. HPLC-UV preceded by derivatization with 2,4-dinitrophenylhydrazine allows separation and detection of bio-oil aldehydes, but the derivatization affected the bio-oil stability reducing their quantitative applicability. GC/MS determination of aldehydes was reached by derivatization with o-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine hydrochloride. Two approaches for this reaction were evaluated. The first: "in solution derivatization and head space extraction" and the second: "on fiber derivatization SPME", the latter through an automatic procedure. Both sample treatments allows the quantification of most important aliphatic aldehydes in bio-oil, being the SPME approach more efficient. The aldehyde concentrations in bio-oil were ~2% formaldehyde, ~!0.1% acetaldehyde and ~0.05% propionaldehyde.

High performance thin layer chromatography determination of cellobiosan and levoglucosan in bio-oil obtained by fast pyrolysis of sawdust.

In this work, high performance thin layer liquid chromatography (HTPLC) is applied to the determination of sugars in fast pyrolysis liquids (bio-oil) and fractions thereof. The proposed procedure allows the separation of anhydrosugar levoglucosan and cellobiosan, as well as glucose, arabinose, xylose and cellobiose. Pre-treatment and derivatization of samples are not necessary and volatile compounds present in bio-oil do not interfere with sugar analysis. The detrimental effect of the complex bio-oil matrix on columns and detector lifetime is avoided by using disposable HTPLC plates. Prior screening of glucose, present especially in aged and aqueous bio-oil fractions, is required to quantify cellobiosan without interference. Concentrations of levoglucosan and cellobiosan in bio-oil samples obtained from Pinus radiata sawdust were ranged between 1.27-2.26% and 0.98-1.96% respectively, while a bio-oil sample obtained from native wood contained a higher levoglucosan concentration.

Photoinactivation of photosystem II: is there more than one way to skin a cat?

We briefly review the main mechanisms proposed for photodamage to photosystem II (PSII), at the donor and acceptor sides, and then discuss the mechanism whereby filamentous cyanobacteria inhabiting biological sand crusts such as Microcoleus sp. are able to avoid serious damage to their photosynthetic machinery. We show that the decline in fluorescence following exposure to excess light does not reflect a reduction in PSII activity but rather the activation of a non-radiative charge recombination in PSII. Furthermore, we show that the difference in the thermoluminescent peak temperature intensities in these organisms, in the presence and absence of inhibitors such as dichlorophenyl-dimethylurea (DCMU), is smaller than observed in model organisms suggesting that the redox gap between Q(A)⁻ and P680+ is smaller. On the basis of these data, we propose that this could enable an alternative, pheophytin-independent recombination, thereby minimizing the damaging ¹O2 production associated with radiative recombination.

Ten-year follow-up in patients with combined heart and kidney transplantation.

BACKGROUND: Combined heart and kidney transplantation has been documented, although data regarding immunosuppression, rejection episodes, and graft or patient survival have not been detailed. We evaluated our experience and more than 10-year outcome with patients selected for combined heart and kidney transplantation. METHODS: Eight patients aged 29 to 59 years were selected for combined heart and kidney transplantation. The indications were end-stage heart disease and underlying renal pathology, or secondary renal insufficiency, or renal failure. Six patients were dialysis dependent before transplantation. There were 7 simultaneous procedures and 1 staged procedure. The heart was transplanted first in all cases. All patients were maintained after transplantation on azathioprine (2 mg x kg(-1) x d(-1)) and whole-blood monoclonal cyclosporine levels at greater than 200 microg/L; prednisone was not decreased to less than 10 mg/d. RESULTS: Seven (87.5%) patients have survived a mean duration of 100.4 months (range, 51-144 months), and each allograft has continued to function. The only death was due to pulmonary emboli and was not related to allograft rejection or failure. Only 4 cardiac and 4 kidney allograft rejections have occurred. Five patients have been free of kidney rejection, 1 patient has been rejection free for more than 8 years, and no patient has had simultaneous rejection. CONCLUSIONS: In select patients, combined heart and kidney transplantation can provide long-term graft function and patient survival. The low rates of rejection support our current approach to immunosuppression. Our experience indicates that end-stage failure of either heart or kidney does not necessarily preclude dual-organ transplantation.