Immp2l Enhances the Structure and Function of Mitochondrial Gpd2 Dehydrogenase.

'Inner mitochondrial membrane peptidase 2 like' (IMMP2L) is a nuclear-encoded mitochondrial peptidase that has been conserved through evolutionary history, as has its target enzyme, 'mitochondrial glycerol phosphate dehydrogenase 2' (GPD2). IMMP2L is known to cleave the mitochondrial transit peptide from GPD2 and another nuclear-encoded mitochondrial respiratory-related protein, cytochrome C1 (CYC1). However, it is not known whether IMMP2L peptidase activates or alters the activity or respiratory-related functions of GPD2 or CYC1. Previous investigations found compelling evidence of behavioural change in the Immp2lKD-/- KO mouse, and in this study, EchoMRI analysis found that the organs of the Immp2lKD-/- KO mouse were smaller and that the KO mouse had significantly less lean mass and overall body weight compared with wildtype littermates (p < 0.05). Moreover, all organs analysed from the Immp2lKD-/- KO had lower relative levels of mitochondrial reactive oxygen species (mitoROS). The kidneys of the Immp2lKD-/- KO mouse displayed the greatest decrease in mitoROS levels that were over 50% less compared with wildtype litter mates. Mitochondrial respiration was also lowest in the kidney of the Immp2lKD-/- KO mouse compared with other tissues when using succinate as the respiratory substrate, whereas respiration was similar to the wildtype when glutamate was used as the substrate. When glycerol-3-phosphate (G3P) was used as the substrate for Gpd2, we observed ~20% and ~7% respective decreases in respiration in female and male Immp2lKD-/- KO mice over time. Together, these findings indicate that the respiratory-related functions of mGpd2 and Cyc1 have been compromised to different degrees in different tissues and genders of the Immp2lKD-/- KO mouse. Structural analyses using AlphaFold2-Multimer further predicted that the interaction between Cyc1 and mitochondrial-encoded cytochrome b (Cyb) in Complex III had been altered, as had the homodimeric structure of the mGpd2 enzyme within the inner mitochondrial membrane of the Immp2lKD-/- KO mouse. mGpd2 functions as an integral component of the glycerol phosphate shuttle (GPS), which positively regulates both mitochondrial respiration and glycolysis. Interestingly, we found that nonmitochondrial respiration (NMR) was also dramatically lowered in the Immp2lKD-/- KO mouse. Primary mouse embryonic fibroblast (MEF) cell lines derived from the Immp2lKD-/- KO mouse displayed a ~27% decrease in total respiration, comprising a ~50% decrease in NMR and a ~12% decrease in total mitochondrial respiration, where the latter was consistent with the cumulative decreases in substrate-specific mediated mitochondrial respiration reported here. This study is the first to report the role of Immp2l in enhancing Gpd2 structure and function, mitochondrial respiration, nonmitochondrial respiration, organ size and homeostasis.

Evaluating Enzymatic Productivity-The Missing Link to Enzyme Utility.

Kinetic productivity analysis is critical to the characterization of enzyme catalytic performance and capacity. However, productivity analysis has been largely overlooked in the published literature. Less than 0.01% of studies which report on enzyme characterization present productivity analysis, despite the fact that this is the only measurement method that provides a reliable indicator of potential commercial utility. Here, we argue that reporting productivity data involving native, modified, and immobilized enzymes under different reaction conditions will be of immense value in optimizing enzymatic processes, with a view to accelerating biotechnological applications. With the use of examples from wide-ranging studies, we demonstrate that productivity is a measure of critical importance to the translational and commercial use of enzymes and processes that employ them. We conclude the review by suggesting steps to maximize the productivity of enzyme catalyzed reactions.

Computational Analysis of Thermal Adaptation in Extremophilic Chitinases: The Achilles' Heel in Protein Structure and Industrial Utilization.

Understanding protein stability is critical for the application of enzymes in biotechnological processes. The structural basis for the stability of thermally adapted chitinases has not yet been examined. In this study, the amino acid sequences and X-ray structures of psychrophilic, mesophilic, and hyperthermophilic chitinases were analyzed using computational and molecular dynamics (MD) simulation methods. From the findings, the key features associated with higher stability in mesophilic and thermophilic chitinases were fewer and/or shorter loops, oligomerization, and less flexible surface regions. No consistent trends were observed between stability and amino acid composition, structural features, or electrostatic interactions. Instead, unique elements affecting stability were identified in different chitinases. Notably, hyperthermostable chitinase had a much shorter surface loop compared to psychrophilic and mesophilic homologs, implying that the extended floppy surface region in cold-adapted and mesophilic chitinases may have acted as a "weak link" from where unfolding was initiated. MD simulations confirmed that the prevalence and flexibility of the loops adjacent to the active site were greater in low-temperature-adapted chitinases and may have led to the occlusion of the active site at higher temperatures compared to their thermostable homologs. Following this, loop "hot spots" for stabilizing and destabilizing mutations were also identified. This information is not only useful for the elucidation of the structure-stability relationship, but will be crucial for designing and engineering chitinases to have enhanced thermoactivity and to withstand harsh industrial processing conditions.

Excision of pediatric craniopharyngioma: pattern of recurrence in 35 patients at a tertiary care hospital in Saudi Arabia.

BACKGROUND AND PURPOSE: Craniopharyngiomas are benign tumors of central nervous system which are known to affect both adults and children. Despite their benign origin, the recurrence is still one of the main postoperative challenges. The aim of this study was to investigate in retrospect factors related to recurrence of craniopharyngioma in a tertiary center in Riyadh, Saudi Arabia. PATIENTS AND METHODS: We conducted a review of charts of all craniopharyngioma patients operated in neurosurgery department at King Faisal Specialist Hospital & Research Center in Riyadh (KFSH-RC). Age at surgery, gender, body mass index, symptoms at presentation, hormonal data, tumor characteristics and location, presence of hydrocephalus, previous treatments, neuroimaging features, surgical results, and recurrence were abstracted from the medical charts of the patients retrospectively. RESULTS: In all, 70.6% of patients had gross total resection (GTR). The recurrence after GTR in our series was 25% which considered low when compared to most surgical series. From all above studied variables, VP shunt insertion at presentation was constantly significant in both uni- and multi-variable analysis. CONCLUSION: In this study, we analyzed several factors to determine if they had any significant correlation with recurrence. Only VP shunt insertion was found significant. Further researches are needed to verify these factors and to discover others.

Successful Outcome in Patients with Fanconi Anemia Undergoing T Cell-Replete Mismatched Related Donor Hematopoietic Cell Transplantation Using Reduced-Dose Cyclophosphamide Post-Transplantation.

Allogeneic hematopoietic cell transplantation (HCT) has been shown to restore normal hematopoiesis in patients with Fanconi anemia (FA), with excellent results in matched related donor HCT. Outcomes of alternative donor HCT are less favorable, however. In patients without FA, several reports have documented stable engraftment and/or a low risk of graft-versus-host disease (GVHD) using unmanipulated HLA-mismatched related donors and post-HCT cyclophosphamide (PT-CY) for GVHD prophylaxis. Data on the use of this approach in patients with FA are scarce, and thus we launched a study of HLA-mismatched related donor HCT in these patient. Here we report our findings in 19 patients. The conditioning was fludarabine 30 mg/m2/day for 5 days, antithymocyte globulin 5 mg/kg/day for 4 days, and total body irradiation (total dose, 200 cGy). GVHD prophylaxis was cyclosporine and mycophenolate and reduced doses of PT-CY, 25 mg/kg, on days +3 and +5. All patients exhibited absolute neutrophil count recovery. Grade III-IV acute GVHD occurred in 3 patients, and chronic GVHD occurred in 1 patient. At a mean follow-up of 38.3 ± 5.8 months, the 5-year probability of overall survival for our patients was 89.2% ± 7.2%. The regimen was well tolerated; hemorrhagic cystitis occurred in 7 patients, and severe mucositis occurred in 5 patients. There were 2 deaths; the primary cause of death was severe GVHD in 1 patient and leukemia recurrence in the other. We conclude that in patients with FA lacking a matched related donor, the use of mismatched related HCT with low-dose PT-CY is a viable option; it is well tolerated, with a high rate of engraftment and an acceptable incidence of GVHD.

Incidence, clinical distribution, and patient characteristics of childhood cancer in Saudi Arabia: A population-based analysis.

PURPOSE: Information regarding the incidence and patterns of childhood malignancies is disproportionately overrepresented by high-income countries, representing mainly the Caucasian population. There is a need to evaluate and disseminate information for other ethnicities, particularly from the Middle East. METHODS: Data from the National Cancer Registry, Saudi Arabia (SA-NCR), for pediatric patients (age 0-14 years) diagnosed between 2005 and 2009 and for similar patients at our institution during the same period were analyzed. Population numbers reported in the 2007 national census were used to calculate the annual incidence of childhood cancer. RESULTS: Data from SA-NCR on 3885 patients were included in this analysis. The median age was 5.58 years, and 57.3% were males. The annual age-specific cancer incidence rate (ASR) for children in SA is 99.83 per million population; ASR per million for lymphoid leukemia is 25.75, 12.05 for brain tumors, and 9.82 for Hodgkin lymphoma. Of all childhood cancers in SA, 35% were treated at our institution. The five-year overall survival for these 1350 patients is 74.6% (median follow-up 7.52 years [95% confidence interval: 7.36-7.68]). Significant differences in the distribution of childhood malignancy subtypes were evident compared with other countries. CONCLUSION: We have reported differences in the cancer ASR and cancer subtype distribution for children in SA as compared with the worldwide incidence and with other populations. This paper provides a comprehensive epidemiological overview of childhood cancer in SA, which could be extrapolated to other regional Arab populations.

Tuscan Varieties of Sweet Cherry Are Rich Sources of Ursolic and Oleanolic Acid: Protein Modeling Coupled to Targeted Gene Expression and Metabolite Analyses.

The potential of six ancient Tuscan sweet cherry (Prunus avium L.) varieties as a source of health-promoting pentacyclic triterpenes is here evaluated by means of a targeted gene expression and metabolite analysis. By using a sequence homology criterion, we identify five oxidosqualene cyclase genes (OSCs) and three cytochrome P450s (CYP85s) that are putatively involved in the triterpene production pathway in sweet cherries. We performed 3D structure prediction and induced-fit docking using cation intermediates and reaction products for some OSCs to predict their function. We show that the Tuscan varieties have different amounts of ursolic and oleanolic acids and that these variations are related to different gene expression profiles. This study stresses the interest of valorizing ancient fruits as alternative sources of functional molecules with nutraceutical value. It also provides information on sweet cherry triterpene biosynthetic genes, which could be the object of follow-up functional studies.

Novel Insights from Comparative In Silico Analysis of Green Microalgal Cellulases.

The assumption that cellulose degradation and assimilation can only be carried out by heterotrophic organisms was shattered in 2012 when it was discovered that the unicellular green alga, Chlamydomonas reinhardtii (Cr), can utilize cellulose for growth under CO2-limiting conditions. Publications of genomes/transcriptomes of the colonial microalgae, Gonium pectorale (Gp) and Volvox carteri (Vc), between 2010⁻2016 prompted us to look for cellulase genes in these algae and to compare them to cellulases from bacteria, fungi, lower/higher plants, and invertebrate metazoans. Interestingly, algal catalytic domains (CDs), belonging to the family GH9, clustered separately and showed the highest (33⁻42%) and lowest (17⁻36%) sequence identity with respect to cellulases from invertebrate metazoans and bacteria, respectively, whereas the identity with cellulases from plants was only 27⁻33%. Based on comparative multiple alignments and homology models, the domain arrangement and active-site architecture of algal cellulases are described in detail. It was found that all algal cellulases are modular, consisting of putative novel cysteine-rich carbohydrate-binding modules (CBMs) and proline/serine-(PS) rich linkers. Two genes were found to encode a protein with a putative Ig-like domain and a cellulase with an unknown domain, respectively. A feature observed in one cellulase homolog from Gp and shared by a spinach cellulase is the existence of two CDs separated by linkers and with a C-terminal CBM. Dockerin and Fn-3-like domains, typically found in bacterial cellulases, are absent in algal enzymes. The targeted gene expression analysis shows that two Gp cellulases consisting, respectively, of a single and two CDs were upregulated upon filter paper addition to the medium.

Identification of fasciclin-like arabinogalactan proteins in textile hemp (Cannabis sativa L.): in silico analyses and gene expression patterns in different tissues.

BACKGROUND: The fasciclin-like arabinogalactan proteins (FLAs) belong to the arabinogalactan protein (AGP) superfamily and are known to play different physiological roles in plants. This class of proteins was shown to participate in plant growth, development, defense against abiotic stresses and, notably, cell wall biosynthesis. Although some studies are available on the characterization of FLA genes from different species, both woody and herbaceous, no detailed information is available on the FLA family of textile hemp (Cannabis sativa L.), an economically important fibre crop. RESULTS: By searching the Cannabis genome and EST databases, 23 CsaFLAs have been here identified which are divided into four phylogenetic groups. A real-time qPCR analysis performed on stem tissues (isolated bast fibres and shivs sampled at three heights), hypocotyls (6-9-12-15-17-20 days-old), whole seedlings, roots, leaves and female/male flowers of the monoecious fibre variety Santhica 27, indicates that the identified FLA genes are differentially expressed. Interestingly, some hemp FLAs are expressed during early phases of fibre growth (elongation), while others are more expressed in the middle and base of the stem and thus potentially involved in secondary cell wall formation (fibre thickening). The bioinformatic analysis of the promoter regions shows that the FLAs upregulated in the younger regions of the stem share a conserved motif related to flowering control and regulation of photoperiod perception. The promoters of the FLA genes expressed at higher levels in the older stem regions, instead, share a motif putatively recognized by MYB3, a transcriptional repressor belonging to the MYB family subgroup S4. CONCLUSIONS: These results point to the existence of a transcriptional network fine-tuning the expression of FLA genes in the older and younger regions of the stem, as well as in the bast fibres/shivs of textile hemp. In summary, our study paves the way for future analyses on the biological functions of FLAs in an industrially relevant fibre crop.

Defying the activity-stability trade-off in enzymes: taking advantage of entropy to enhance activity and thermostability.

The biotechnological applications of enzymes are limited due to the activity-stability trade-off, which implies that an increase in activity is accompanied by a concomitant decrease in protein stability. This premise is based on thermally adapted homologous enzymes where cold-adapted enzymes show high intrinsic activity linked to enhanced thermolability. In contrast, thermophilic enzymes show low activity around ambient temperatures. Nevertheless, genetically and chemically modified enzymes are beginning to show that the activity-stability trade-off can be overcome. In this review, the origin of the activity-stability trade-off, the thermodynamic basis for enhanced activity and stability, and various approaches for escaping the activity-stability trade-off are discussed. The role of entropy in enhancing both the activity and the stability of enzymes is highlighted with a special emphasis placed on the involvement of solvent water molecules. This review is concluded with suggestions for further research, which underscores the implications of these findings in the context of productivity curves, the Daniel-Danson equilibrium model, catalytic antibodies, and life on cold planets.

Risk-adapted stratification for optimally intensive treatment assignment of pediatric patients with non-Hodgkin lymphoma is an effective strategy in developing countries.

BACKGROUND: Pediatric patients with non-Hodgkin lymphoma (NHL) in developing countries (DCs) present with greater tumor load even at lower stages and with comorbidities that impact therapy delivery. This causes toxic mortality with "standard" intensive protocols or recurrences with "gentler" treatment. OBJECTIVES: We developed and evaluated a risk stratification schema that guides intensity of therapy. DESIGN/METHODS: Sixty-nine patients were prospectively assigned to five risk groups (A-E; n = 6, 15, 16, 15, and 17) following staging and treated with protocols of risk-stratified intensity. Risk stratification utilized St. Jude stage, disease bulk, and sites involved. RESULTS: Between 2006 and 2011, 69 patients with B-cell NHL were enrolled. Among these, 72.5% were boys with mean age of 6.9 years (±3.33 [SD]; range 2.4-14.2 years). Eighty-seven percent had Burkitt lymphoma, 82.6% had advanced stage (25 [36.2%] stage III; 32 [46.4%] stage IV), and 24.6% were central nervous system positive. Mean lactate dehydrogenase increased progressively across the risk strata. Among these, 0/6, 1/15, 3/16, 2/15, and 7/17 patients relapsed/progressed within each risk stratum. Fifteen patients died; three from treatment-related toxicity. At a median follow-up of 6.2 years, the overall and event-free survival (EFS) for all patients was 78.1 and 75.4%, respectively; EFS was related to risk assignment. The frequency of documented infectious and noninfectious toxicities increased with higher risk group assignment causing prolongation of admissions and potential treatment delays. CONCLUSIONS: Reduction in treatment intensity for an identified subset of patients with NHL is feasible, while high-intensity therapy is required for high-risk groups. This risk stratification system may be a first step toward improving the outcomes in some DCs.

Factors Determining the Outcome of Hematopoietic Stem Cell Transplantation in Patients With Acute Lymphoblastic Leukemia at King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia.

Medical records of 82 patients with acute lymphoblastic leukemia (ALL) who underwent hematopoietic cell transplantation (HCT) at our institution from 2005 to 2011 were reviewed. Forty-five patients were male (54.8%). The median age at HCT was 7.46 years (range, 0.98 to 14.31 y), the median time to HCT after diagnosis was 12.56 months. Ten patients were below the age of 1 year (12%). All patients were in complete remission at the time of HCT. In 83 transplants, 64 patients received HCT from human leukocyte antigen-identical-related donors and 19 from other donors. Stem cell source was bone marrow in 65 (78%) and cord blood in 18 (22%). Five-year overall survival was 58.8% and event-free survival was 54.3%. The cumulative incidence of acute graft versus host disease was 4.8%±2.3% and of chronic graft versus host disease was 8.9%±3.2%. The median time to absolute neutrophil count and platelet recovery was 17 days (range, 12 to 43 d) and 28 days (range, 15 to 98 d), respectively. One patient acquired CMV infection after transplant. No one developed venoocclusive disease, hemorrhagic cystitis, or other complication. Patient's age at diagnosis, sex, donor's human leukocyte antigen status and sex, source of transplant and complete remission status at HCT did not affect overall survival and event-free survival. Our results show a favorable outcome to HCT for acute lymphoblastic leukemia patients comparable to published data, and no single factor was associated with superior outcome.

Factors affecting the outcome of related allogeneic hematopoietic cell transplantation in patients with Fanconi Anemia.

Hematopoietic cell transplantation (HCT) can cure bone marrow failure in patients with Fanconi Anemia (FA), and it is generally accepted that these patients should receive low-intensity conditioning because of the underlying DNA repair defect in their cells. Outcomes for recipients of matched related HCT have generally been favorable, but only a few studies have scrutinized the factors that may affect the eventual outcome of these patients. This retrospective analysis of 94 pediatric patients with FA who underwent related HCT at King Faisal Specialist Hospital & Research Center was carried out to attempt to identify factors that may affect outcome. Results showed overall survival (OS) probabilities of 92.5%, 89%, and 86% at 1, 5, and 10 years, respectively. In univariate analysis, use of higher dose cyclophosphamide (CY) (60 mg/kg) conditioning was associated with a better 10-year OS than lower dose CY (20 mg/kg) conditioning (91% versus 82%, respectively; P = .035), and use of radiation-containing regimens was associated with a significantly lower 10-year OS than nonradiation regimens (76% versus 91%, respectively; P = .005). Of the 4 regimens used in this study, the fludarabine-based regimen was associated with the highest survival (95.2%; P = .034). The use of the higher dose CY (60 mg/kg) was associated with a significantly increased incidence of hemorrhagic cystitis (HC) (20% versus 5.6% respectively; P = .049). Three patients (3%) developed squamous cell carcinoma (2 oropharyngeal and 1 genitourinary), at 9.4, 5.4, and 13.3 years after HCT; 2 of them had radiation-containing conditioning. In conclusion, our data suggest that although using a higher dose CY (60 mg/kg) conditioning regimen may be associated with better survival, it is also associated with a significantly increased risk of HC. The addition of fludarabine to the low-dose CY (20 mg/kg) is associated with the best survival. On the other hand, radiation-containing regimens are associated with significantly lower survival.

Radioactive iodine refractoriness in Middle Eastern differentiated thyroid cancer: clinical outcome and risk factor analysis.

Background: Radioactive iodine refractory differentiated thyroid cancer (RAIR-DTC) has received increasing attention due to its poor prognosis. However, outcomes may vary among patients with RAIR-DTC. The role of clinico-pathological and molecular prognostic factors in survival remains controversial, resulting in difficulty in selecting patients for new targeted therapies. We assessed mortality rate and DTC-specific survival in Middle Eastern RAIR-DTC to identify prognostic factors associated with survival. Methods: This single center, retrospective study enrolled 268 patients with RAIR-DTC. Mortality rate and DTC-specific survival were analyzed to identify prognostic factors related to survival. Univariate and multivariate analysis were performed using Cox proportional hazards model. Results: Of the 268 cases of RAIR-DTC, 40.3% (108/268) had absent 131I uptake (either on diagnostic or post-therapy whole body scan), 15.3% (41/268) had progressive disease (PD) despite 131I, 7.5% (20/268) had persistent disease despite cumulative activity of I131 of >600 mCi and 36.9% (n=99/268) developed distant metastasis. On multivariate analysis, age (more than 45 years), presence of metastatic disease and tumors harboring telomerase reverse transcriptase (TERT) promoter mutations were independent prognostic factors for poor DTC-specific survival. Subjects were divided into 3 groups according to the number of risk factors; low risk (no risk factors); intermediate (≤ 2 risk factors); and high risk (all the 3 risk factors). Ten-year DTC-specific survival rates in low, intermediate and high-risk groups were 100.0%, 92.9% and 53.6%, respectively. Conclusions: The contribution of age greater than 45 years to RAIR-DTC mortality is impactful. Older age, presence of distant metastasis and TERT mutations could be used as early predictors of RAIR-DTC cases. The identification of prognostic factors for poor survival in RAIR-DTC may improve the selection of patients for more personalized surveillance and therapeutic modalities.

Enhanced biodegradation of phenanthrene and anthracene using a microalgal-bacterial consortium.

Polycyclic aromatic hydrocarbons (PAHs) are chemicals that are released into the environment during activities of the petroleum industry. The bioaccumulation, carcinogenic and mutagenic potential of PAHs necessitates the bioremediation of these contaminants. However, bioremediation of PAHs has a number of limitations including the inability of a single microbe to degrade all of the PAH fraction's environmental constituents. Therefore, a different paradigm, employing microalgal-bacterial consortium (MBC), may be used to effectively remove PAHs contaminants. In this type of interaction, the microalgae and bacteria species in the consortium work together in a way that enhances the overall performance of the MBC. Bacterial species in the consortium provide essential nutrients or growth factors by degrading toxic substances and provide these to microalgae, while the microalgae species provide organic carbon for the bacterial species to grow. For the first time, the ability of Gonium pectorale (G. pectorale) microalgae to break down phenanthrene (PHE) and anthracene (ANT) was investigated. Phenanthrene was shown to be more effectively degraded by G. pectorale (98%) as compared to Bacillus licheniformis (B. licheniformis) 19%. Similarly, G. pectorale has effectively degrade anthracene (98%) as compared with B. licheniformis (45%). The consortia of G. pectorale and B. licheniformis has shown a slight increase in the degradation of PHE (96%) and ANT (99%). Our findings show that B. licheniformis did not inhibit the growth of G. pectorale and in the consortia has effectively eliminated the PAHs from the media. Therefore G. pectorale has a tremendous potential to remove PAHs from the polluted environment. Future research will be conducted to assess Gonium's capacity to eliminate PAHs that exhibit high molar masses than that of PHE and ANT.

Is Mixed Chimerism Post-allogeneic Hematopoietic Stem Cell Transplantation in Pediatric Acute Lymphoid Leukemia a Prognostic Factor for Relapse?

Hematopoietic stem cell transplantation (HSCT) has been considered curative for children with high-risk acute leukemia (ALL), offering better survival. Short tandem repeat has been used as a marker of chimerism status after HSCT. The appearance of recipient cells >1% post-allogeneic stem cell transplant is defined as mixed chimerism (MC). Chimeric studies post-HSCT are dynamic. This study aimed to investigate the significance of recipient cells in post-HSCT pediatric ALL patients as a predictor of relapse of their primary disease. The rate of MC was 51.4% (19 out of 37 recipients). It was 48.6% (n = 18) during Day+100 and 12.9% (4 out of 31 recipients) during post-Day+100 follow-up until two years. No significant association was noted between MC and all grade overall acute graft-versus-host disease. A mortality rate of 35.1% (n = 13) and a median follow-up of 56.9 months (95% CI: 39.7-74.2) were observed for all but four (16.7%) of the survivors in remission. Regarding causes of death, transplant-related mortality was recorded in only 2 of 13 expired patients (15.4%); both succumbed to sepsis. No significant association was found between MC and primary causes of death. The cumulative probability of five-year overall survival and event-free survival was not found to be statistically significantly different for MC (≤1.0% vs. > 1.0%). In conclusion, our data did not show MC testing alone as an effective prognostic marker for detecting relapse; molecular and flow cytometric analyses should be considered in children with ALL post-HSCT for monitoring relapse.

Corrigendum: Enhanced biodegradation of phenanthrene and anthracene using a microalgal-bacterial consortium.

[This corrects the article DOI: 10.3389/fmicb.2023.1227210.].

Can the bone marrow harvest volume be reduced safely in hematopoietic stem cell transplantation with pediatric sibling donors?

Background: Reduced harvest volumes in pediatric donors appear to have the potential to reduce donor-associated risks while maintaining engraftment in recipients; however, the allowable harvest volume reduction remains undefined. Methods: We retrospectively analyzed the data pairs of 553 bone marrow (BM) harvests from pediatric (age at harvest <18 yr) sibling donors and clinical outcomes of 553 pediatric (age at infusion <14 yr) transplant-naïve recipients to assess the optimal BM harvest volume needed from pediatric donors to obtain the desired CD34+ cell count (≥3.0×106 cells per kg of recipient weight), and to study its impact on the clinical outcomes of transplantation in pediatric recipients. Results: The minimum desired CD34+ cell count of ≥3.0×106 per kg of recipient weight was achieved for 506 (95.3%) of donor-recipient pairs. The median CD34+ cell yield was 6.4×106 per kg of recipient weight (range, 1.2‒33.8×106) in donors younger than 5 years old at harvest, 4.7×106 (range, 0.3‒28.5×106) in donors aged 5‒10 years and 2.1×106 (range, 0.3‒11.3×106) in donors older than 10 years (P<0.001). Conclusion: The infused CD34+ cell dose (×106 cells/kg of recipient weight) had no impact on GRFS; however, a CD34+ cell dose of ＞7×106 cells/kg of recipient weight did not improve hematopoietic recovery.

Clofarabine in Pediatric Acute Relapsed or Refractory Leukemia: Where Do We Stand on the Bridge to Hematopoietic Stem Cell Transplantation?

Background: Despite pronounced improvement in overall survival (OS) in pediatric leukemia, a proportion of patients continue to suffer from lack of response or relapse, and the management of such patients is exceedingly difficult. Immunotherapy and engineered chimeric antigen receptor (CAR) T-cell therapy have shown promising results in the course of relapsed or refractory acute lymphoblastic leukemia (ALL). However, conventional chemotherapy continues to be utilized for re-induction purposes whether independently or in combination with immunotherapy. Methods: Forty-three pediatric leukemia patients (age < 14 years at diagnosis) consecutively diagnosed at our institution and got treated with clofarabine based regimen at a single tertiary care hospital between January 2005 and December 2019 were enrolled in this study. ALL comprised of 30 (69.8%) patients of the cohort while the remaining 13 (30.2%) were with acute myeloid leukemia (AML). Results: Post-clofarabine bone marrow (BM) was negative in 18 (45.0%) cases. Overall clofarabine failure rate was 58.1% (n = 25) with 60.0% (n = 18) in ALL and 53.8% (n = 7) in AML (P = 0.747). Eighteen (41.9%) patients eventually underwent hematopoietic stem cell transplantation (HSCT); 11 (61.1%) were from ALL group and remaining seven (38.9%) were AML (P = 0.332). Three- and 5-year OS of our patients was 37.7±7.6% and 32.7±7.3%. There was a trend of better OS for ALL patients compared to AML (40.9±9.3% vs. 15.4±10.0%, P = 0.492). Cumulative probability of 5-year OS was significantly better in transplanted patients (48.1±12.1% vs. 21.4±8.4%, P = 0.024). Conclusions: Though almost 90% of our patients proceeded to HSCT with complete response post-clofarabine treatment, yet clofarabine-based regimens are associated with the significant burden of infectious complications and sepsis-related deaths.

Predictive risk factors for distant metastasis in pediatric differentiated thyroid cancer from Saudi Arabia.

Background: Despite their excellent prognosis, children and young adults (CAYA) with differentiated thyroid cancer (DTC) tend to have more frequent occurrence of distant metastasis (DM) compared to adult DTC. Data about DM in CAYA from Middle Eastern ethnicity is limited. Methods: Medical records of 170 patients with DTC ≤18 years were retrospectively reviewed. Clinico-pathological factors associated with lung metastasis in CAYA, their clinical presentation and outcome were analyzed. Rick factors related to distant metastasis-free survival (DMFS) for the whole cohort were evaluated. Results: DM was observed in 27 patients and all were lung metastasis. Lung metastasis was significantly associated with younger age (≤15 years), extrathyroidal extension (ETE), multifocal tumors, bilaterality, presence of lymph node (LN) disease and high post-operative stimulated thyroglobulin (sTg). Highest negative predictive values were seen with low post-operative sTg (97.9%), absence of LN disease (93.8%), absence of ETE (92.2%) and age older than 15 years (92.9%). Post-therapy whole body scan (WBS) identified most of the lung metastasis (21 of 27; 77.8%). Upon evaluating patients response according to ATA guidelines, excellent response was seen in only one patient, while biochemical persistence and structural persistence were seen in 11.1% (3/27) and 77.8% (21/27), respectively. Elevated post-operative sTg (>10ng/ml) was the only risk factor found to be significantly associated with both biochemical persistence (with or without structural persistence (p = 0.0143)) and structural persistence (p = 0.0433). Cox regression analysis identified age and post-operative sTg as independent risk factors related to DMFS. Based on these two risk factors for DMFS, patients were divided into 3 groups: low risk (no risk factors), intermediate risk (1 risk factor) and high risk (both risk factors). 20-year DMFS rates in the low-, intermediate- and high-risk groups were 100.0%, 81.3% and 23.7% respectively (p < 0.0001). Conclusion: Higher suspicion for metastatic pediatric DTC should be considered in patients who are young, have LN disease, extrathyroidal extension and elevated post-operative sTg. Persistent disease, despite therapy, is very common and it appears to be related to post-operative sTg level. Hence, risk adaptive management is desirable in CAYA with DTC.