The frequency of NUDT15 rs116855232 and its impact on mercaptopurine-induced toxicity in Syrian children with acute lymphoblastic leukemia

Introduction

Polymorphisms in NUDT15 may result in differences in mercaptopurine-induced toxicity. This study aimed to identify the frequency of the NUDT15 (c.415C>T; rs116855232) polymorphism and investigate the effect of this polymorphism on mercaptopurine-induced toxicity in a population of Syrian patients with childhood acute lymphoblastic leukemia (ALL).

Methods

This is a retrospective study that included children with ALL reaching at least 6 months of maintenance therapy. The NUDT15 genotyping was determined using standard targeted sequencing of polymerase chain reaction products. The odds ratio (OR) for the association between toxicity and genotype was evaluated.

Results

A total of 92 patients were enrolled. The majority of the patients in the study population were low-risk (63.04%), followed by intermediate-risk (25%), and high-risk (11.96%). There were 5 patients (5.4%) with NUDT15 (c.415C>T; rs116855232) CT genotype, and 1 patient (1.08%) with NUDT15 TT genotype, with allele frequencies of C=0.962 and T=0.038. The mercaptopurine median dose intensity was 100%, 54.69%, and 5% for the genotypes CC, CT, and TT, respectively (P=0.009). Early onset leukopenia was significantly associated with the NUDT15 polymorphism (OR: 6.16, 95% CI: 1.11-34.18, P=0.037). There was no association between the NUDT15 genotype and hepatotoxicity.

Conclusion

Approximately 6.5% of the study population exhibited reduced NUDT15 activity. The mercaptopurine dose intensity was considerably low in NUDT15 rs116855232 TT genotype compared with CT and CC. The dosage of mercaptopurine should be adjusted according to the NUDT15 genotype in pediatric patients with ALL.

Improved production of Bacillus subtilis cholesterol oxidase by optimization of process parameters using response surface methodology

BACKGROUND

Cholesterol oxidase has numerous biomedical and industrial applications. In the current study, a new bacterial strain was isolated from sewage and was selected for its high potency for cholesterol degradation (%) and production of high cholesterol oxidase activity (U/OD600).

RESULTS

Based on the sequence of 16S rRNA gene, the bacterium was identified as Bacillus subtilis. The fermentation conditions affecting cholesterol degradation (%) and the activity of cholesterol oxidase (U/OD600) of B. subtilis were optimized through fractional factorial design (FFD) and response surface methodology (RSM). According to this sequential optimization approach, 80.152% cholesterol degradation was achieved by setting the concentrations of cholesterol, inoculum size, and magnesium sulphate at 0.05 g/l, 6%, and 0.05 g/l, respectively. Moreover, 85.461 U of cholesterol oxidase/OD600 were attained by adjusting the fermentation conditions at initial pH, 6; volume of the fermentation medium, 15 ml/flask; and concentration of cholesterol, 0.05 g/l. The optimization process improved cholesterol degradation (%) and the activity of cholesterol oxidase (U/OD600) by 139% and 154%, respectively. No cholesterol was detected in the spectroscopic analysis of the optimized fermented medium via gas chromatography-mass spectroscopy (GC-MS).

CONCLUSION

The current study provides principal information for the development of efficient production of cholesterol oxidase by B. subtilis that could be used in various applications.

Inhibition of Pseudomonas aeruginosa quorum sensing by methyl gallate from Mangifera indica

Antipathogenic drugs are a potential source of therapeutics, particularly following the emergence of multiple drug-resistant pathogenic microorganisms in the last decade. The inhibition of quorum sensing (QS) is an advanced antipathogenic approach for suppression of bacterial virulence and dissemination. This study aimed to investigate the inhibitory effect of some Egyptian medicinal plants on the QS signaling system of Pseudomonas aeruginosa. Among the tested plants, Mangifera indica exhibited the highest quorum sensing inhibition (QSI) activity against Chromobacterium violaceum ATCC 12472. Four pure compounds were extracted and identified; of these, methyl gallate (MG) showed the most potent QSI. MG had a minimum inhibitory concentration (MIC) of 512 g/mL against P. aeruginosa strains PAO1, PA14, Pa21, Pa22, Pa23, Pa24, and PAO-JP2. The virulence factors of PAO1, PA14, Pa21, Pa22, Pa23, and Pa24 were significantly inhibited by MG at 1/4 and 1/2 sub-MICs without affecting bacterial viability. Computational insights were performed by docking the MG compound on the LasR receptor, and the QSI behavior of MG was found to be mediated by three hydrogen bonds: Trp60, Arg61, and Thr75. This study indicates the importance of M. indica and MG in the inhibition and modulation of QS and QS-related virulence factors in P. aeruginosa.

The Psychosocial Impact of the COVID-19 Pandemic on Families of Children With Cancer in the Low-income Setting

The coronavirus disease 2019 (COVID-19) pandemic has had a profound effect on families' psychosocial well-being worldwide. This study aimed to investigate the pandemic's impact on families of children with cancer in a low-income setting in Syria. The study conducted a cross-sectional survey of 50 families of children with cancer receiving treatment at a nongovernmental organization-based pediatric oncology unit in Syria. The survey used the Corona Anxiety Scale (CAS) to assess the pandemic's impact on families' anxiety, and other items to evaluate the financial toxicity of the strict measures implemented during the pandemic's first months. The study's results revealed that the COVID-19 pandemic significantly negatively impacted the psychosocial well-being of families of children with cancer in Syria. Specifically, 22% of families reported a major increase in anxiety levels (CAS of >9), and the majority of families (84%) reported excessive indirect financial costs, including travel and living expenses. The study emphasizes the significant social and psychological impact of the COVID-19 pandemic on families of children with cancer in Syria, highlighting the need for additional psychosocial interventions to mitigate future global health crises or pandemics' impact on this vulnerable population. The interventions should prioritize promoting resilience and adaptive coping strategies.

It is the time for quorum sensing inhibition as alternative strategy of antimicrobial therapy

Multiple drug resistance poses a significant threat to public health worldwide, with a substantial increase in morbidity and mortality rates. Consequently, searching for novel strategies to control microbial pathogenicity is necessary. With the aid of auto-inducers (AIs), quorum sensing (QS) regulates bacterial virulence factors through cell-to-cell signaling networks. AIs are small signaling molecules produced during the stationary phase. When bacterial cultures reach a certain level of growth, these molecules regulate the expression of the bound genes by acting as mirrors that reflect the inoculum density.Gram-positive bacteria use the peptide derivatives of these signaling molecules, whereas Gram-negative bacteria use the fatty acid derivatives, and the majority of bacteria can use both types to modulate the expression of the target gene. Numerous natural and synthetic QS inhibitors (QSIs) have been developed to reduce microbial pathogenesis. Applications of QSI are vital to human health, as well as fisheries and aquaculture, agriculture, and water treatment. Video Abstract.

2,4-Dichlorophenol biotransformation using immobilized marine halophilic Bacillus subtilis culture and laccase enzyme: application in wastewater treatment

Background

2,4-Dichlorophenol (2,4-DCP) is a very toxic aromatic compound for humans and the environment and is highly resistant to degradation. Therefore, it is necessary to develop efficient remediation and cost-effective approaches to this pollutant. Microbial enzymes such as laccases can degrade phenols, but limited information is known about immobilized bacterial laccase and their reuse.

Methods

Immobilization of marine halophilic Bacillus subtilis AAK cultures via entrapment and adsorption techniques and degradation of different phenolic compounds by immobilized cells were estimated. Partial purification and immobilization of laccase enzymes were carried out. In addition, the biodegradation of 2,4-DCP and others contaminated by wastewater was investigated.

Results

Immobilization of cells and partially purified laccase enzymes by adsorption into 3% alginate increased 2,4-DCP biotransformation compared with free cells and free enzymes. In addition, the reuse of both the immobilized culture and laccase enzymes was evaluated. The highest removal of 2,4-DCP from pulp and paper wastewater samples inoculated by immobilized cells and the immobilized enzyme was 90% and 95%, respectively, at 50 h and 52 h of incubation, compared to free cells and free enzyme.

Conclusion

The results of this study have revealed the immobilization of a biocatalyst and its laccase enzyme as a promising technique for enhancing the degradation of 2,4-DCP and other toxic phenolic and aromatic compounds. The reuse of the biocatalyst and its laccase enzyme enabled the application of this cost-effective bioremediation strategy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s43141-022-00417-1.

Suggested Sustainable Medical and Environmental Uses of Melanin Pigment From Halotolerant Black Yeast Hortaea werneckii AS1

The marine ecosystem is a complex niche with unique environmental circumstances. Microbial communities from the sea are one of the main origins of compounds with tremendous capabilities. Marine yeasts have the ability to produce secondary metabolites that are architecturally distinct from those found in terrestrial species. Melanin pigment synthesized by marine halotolerant black yeast Hortaea werneckii AS1 isolated from Mediterranean salt lakes in Alexandria, Egypt was found to exert a radical scavenging effect on 2,2-diphenyl-1-picrylhydrazyl (DPPH) with an IC₅₀ of 61.38 μg/ml. Furthermore, it showed no cytotoxicity toward human skin fibroblast cell line (HSF) with an IC₅₀ value above 0.1 mg/ml. The antimicrobial capability of the pigment was revealed against the tested number of bacterial and fungal strains with the highest inhibition zone of 25 mm against Aeromonas sp. and a growth inhibition percentage up to 63.6% against Aspergillus niger. From an environmental impact point of view, the pigment disclosed a heavy metal removal efficiency of 85.7, 84.8, and 81.5% for Pb²⁺, Cd²⁺, and Ni²⁺, respectively, at 100 mg/L metal concentration. The previously mentioned results suggested melanin from H. werneckii AS1 as a promising biocompatible candidate in various medical, cosmetics, pharmaceutical, and environmental applications.

Optimization of melanin pigment production from the halotolerant black yeast Hortaea werneckii AS1 isolated from solar salter in Alexandria

Background

Melanins are one of the magnificent natural pigments synthesized by a wide range of microorganisms including different species of fungi and bacteria. Marine black yeasts appear to be potential prospects for the synthesis of natural melanin pigment. As a result, the goal of this research was to isolate a marine black yeast melanin-producing strain and improve the culturing conditions in order to maximize the yield of such a valuable pigment.

Results

Among five locally isolated black yeast strains, the only one that demonstrated a potent remarkable melanin pigment production was identified using ITS rDNA as Hortaea werneckii AS1. The extracted pigment’s physiochemical characterization and analytical investigation with Ultraviolet-Visible (UV) spectrophotometry, Fourier Transform-Infrared spectroscopy (FTIR), and Scanning Electron Microscope (SEM) confirmed its nature as a melanin pigment. The data obtained from the polynomial model’s maximum point suggested that CaCl₂, 1.125 g/L; trace element, 0.25 ml/L; and a culture volume 225 mL/500 mL at their optimal values were the critical three elements impacting melanin production. In comparison with the baseline settings, the response surface methodology (RSM) optimization approach resulted in a 2.0 - fold improvement in melanin output.

Conclusions

A maximum melanin yield of 0.938 g/L proved the halotolerant H. werneckii AS1 potentiality as a source for natural melanin pigment synthesis ‘when compared to some relevant black yeast strains’ and hence, facilitating its incorporation in a variety of pharmaceutical and environmental applications.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-022-02505-1.

Molecular cloning, heterologous expression, and in silico sequence analysis of Enterobacter GH19 class I chitinase (chiRAM gene)

BACKGROUND

Using in silico sequence analyses, the present study aims to clone and express the gene-encoding sequence of a GH19 chitinase from Enterobacter sp. in Escherichia coli.

METHODS AND RESULTS

The putative open reading frame of a GH19 chitinase from Enterobacter sp. strain EGY1 was cloned and expressed into pGEM®-T and pET-28a (+) vectors, respectively using a degenerate primer. The isolated nucleotide sequence (1821 bp, GenBank accession no.: MK533791.2) was translated to a chiRAM protein (606 amino acids, UniProt accession no.: A0A4D6J2L9). The in silico protein sequence analysis of chiRAM revealed a class I GH19 chitinase: an N-terminus signal peptide (Met¹-Ala²³), a catalytic domain (Val⁸³-Glu³⁴⁷ and the catalytic triad Glu¹⁴⁹, Glu¹⁷¹, and Ser²¹⁸), a proline-rich hinge region (Pro⁴¹⁴ -Pro⁴⁵⁰), a polycystic kidney disease protein motif (Gly ⁴⁶⁵-Ser ⁵³³), a C-terminus chitin-binding domain (Ala⁵⁵³- Glu⁵⁹³), and conserved class I motifs (NYNY and AQETGG). A three-dimensional model was constructed by LOMETS MODELLER of PDB template: 2dkvA (class I chitinase of Oryza sativa L. japonica). Recombinant chiRAM was overexpressed as inclusion bodies (IBs) (~ 72 kDa; SDS-PAGE) in 1.0 mM IPTG induced E. coli BL21 (DE3) Rosetta strain at room temperature 18 h after induction. Optimized expression yielded active chiRAM with 1.974 ± 0.0002 U/mL, on shrimp colloidal chitin (SCC), in induced E. coli BL21 (DE3) Rosetta cells growing in SB medium. LC-MS/MS identified a band of 72 kDa in the soluble fraction with a 52.3% coverage sequence exclusive to the GH19 chitinase of Enterobacter cloacae (WP_063869339.1).

CONCLUSIONS

Although chiRAM of Enterobacter sp. was successfully cloned and expressed in E. coli with appreciable chitinase activity, future studies should focus on minimizing IBs to facilitate chiRAM purification and characterization.

Treatment-induced cerebral sinus venous thrombosis in childhood acute lymphoblastic malignancies: New risk factors to consider

BACKGROUND

Cerebral sinus venous thrombosis (CSVT) is one of the many side effects encountered during acute lymphoblastic leukemia (ALL) therapy. Due to the rarity of cases, lack of data, and consensus management, no recommendations exist to target the population at risk.

METHODS

This is a retrospective chart review of 229 consecutive patients diagnosed with ALL with an age range of 1-21 years, treated at the Children's Cancer Center of Lebanon between October 2007 and February 2018.

RESULTS

The incidence of CSVT was 10.5%. Using univariate analysis, increased risk of CSVT was observed with male gender, age >10 years, T-cell immunophenotype, intermediate/high-risk disease, maximum triglyceride (TG) level of >615 mg/dl, presence of mediastinal mass, and larger body surface area (BSA). With multivariate analysis, the only statistically significant risk factors were maximum TG level, BSA, presence of mediastinal mass, and risk stratification (intermediate/high risk).

CONCLUSION

Our study was able to unveil TG level of >615 mg/dl, mediastinal mass, and a larger BSA as novel risk factors that have not been previously discussed in the literature.

Quorum Sensing Inhibiting Activity of Cefoperazone and Its Metallic Derivatives on Pseudomonas aeruginosa

The last decade has witnessed a massive increase in the rate of mortalities caused by multidrug-resistant Pseudomonas aeruginosa. Therefore, developing new strategies to control virulence factors and pathogenicity has received much attention. One of these strategies is quorum sensing inhibition (QSI) which was developed to control Pseudomonas infection. This study aims to validate the effect of one of the most used β-lactam antibiotics; cefoperazone (CFP) and its metallic-derivatives on quorum sensing (QS) and virulence factors of P. aeruginosa. Assessment of quorum sensing inhibitory activity of CFP, cefoperazone Iron complex (CFPF) and cefoperazone Cobalt complex (CFPC) was performed by using reporter strain Chromobacterium violaceum ATCC 12472. Minimal inhibitory concentration (MIC) was carried out by the microbroth dilution method. The influence of sub-MICs (1/4 and 1/2 MICs) of CFP, CFPF and CFPC on virulence factors of P. aeruginosa was evaluated. Data was confirmed on the molecular level by RT-PCR. Also, molecular docking analysis was conducted to figure out the possible mechanisms of QSI. CFP, CFPF, and CFPC inhibited violacein pigment production of C. violaceum ATCC 12472. Sub-MICs of CFP (128- 256 μg/mL), and significantly low concentrations of CFPC (0.5- 16 μg/mL) and CFPF (0.5- 64 μg/mL) reduced the production of QS related virulence factors such as pyocyanin, protease, hemolysin and eliminated biofilm assembly by P. aeruginosa standard strains PAO1 and PA14, and P. aeruginosa clinical isolates Ps1, Ps2, and Ps3, without affecting bacterial viability. In addition, CFP, CFPF, and CFPC significantly reduced the expression of lasI and rhlI genes. The molecular docking analysis elucidated that the QS inhibitory effect was possibly caused by the interaction with QS receptors. Both CFPF and CFPC interacted strongly with LasI, LasR and PqsR receptors with a much high ICM scores compared to CFP that could be the cause of elimination of natural ligand binding. Therefore, CFPC and CFPF are potent inhibitors of quorum sensing signaling and virulence factors of P. aeruginosa.

The Inhibitory Effect of Wheat Husks Addition on Aflatoxins Production by Aspergillus flavus in Liquid Culture With Various Wheat Compositions as Carbon Sources

Wheat may be infected by the aflatoxigenic mold Aspergillus flavus during pre- and post-harvest activities. Control strategies reported to manage aflatoxin contamination of wheat are expensive and require extensive testing to verify the absence of toxic secondary metabolites or newly formed compounds. The objective of this study was to develop an in vitro new control strategy based on assessing the influence of wheat husks on aflatoxin production by A. flavus in liquid culture. The results showed that aflatoxin production is significantly influenced by the existence of husks in the wheat forms used as carbon substrates according to the following order: full wheat grains < half-crushed wheat grains < wheat flour 82% < wheat flour 72%. By applying a fractional factorial design and a response surface methodology, maximum aflatoxin production (2.567 ng/mg) was predicted when wheat flour 72% (39 g/l) as a carbon source, yeast extract (5 g/l), and a 75-ml medium volume/250 ml flask were utilized. At this optimized condition, after addition of wheat husk extract, the growth and synthesis of aflatoxins of A. flavus were repressed by 74.85 and 98.72%, respectively. This finding paves the way to examine the antifungal potential of wheat husk constituents and to compare their efficacy with thyme, cinnamon, sweet basil, and coriander essential oils, which possess antimycotic activities. Accordingly, the wheat husk component SiO₂ showed the highest growth inhibition (67.04%) and reduction of A. flavus aflatoxins (82.67%). These results are comparable to those obtained from various examined antimycotic essential oils.

Impact of the coronavirus disease 2019 (COVID-19) pandemic on pediatric oncology care in the Middle East, North Africa, and West Asia region: A report from the Pediatric Oncology East and Mediterranean (POEM) group

Background

Childhood cancer is a highly curable disease when timely diagnosis and appropriate therapy are provided. A negative impact of the coronavirus disease 2019 (COVID‐19) pandemic on access to care for children with cancer is likely but has not been evaluated.

METHODS

A 34‐item survey focusing on barriers to pediatric oncology management during the COVID‐19 pandemic was distributed to heads of pediatric oncology units within the Pediatric Oncology East and Mediterranean (POEM) collaborative group, from the Middle East, North Africa, and West Asia. Responses were collected on April 11 through 22, 2020. Corresponding rates of proven COVID‐19 cases and deaths were retrieved from the World Health Organization database.

Results

In total, 34 centers from 19 countries participated. Almost all centers applied guidelines to optimize resource utilization and safety, including delaying off‐treatment visits, rotating and reducing staff, and implementing social distancing, hand hygiene measures, and personal protective equipment use. Essential treatments, including chemotherapy, surgery, and radiation therapy, were delayed in 29% to 44% of centers, and 24% of centers restricted acceptance of new patients. Clinical care delivery was reported as negatively affected in 28% of centers. Greater than 70% of centers reported shortages in blood products, and 47% to 62% reported interruptions in surgery and radiation as well as medication shortages. However, bed availability was affected in <30% of centers, reflecting the low rates of COVID‐19 hospitalizations in the corresponding countries at the time of the survey.

Conclusions

Mechanisms to approach childhood cancer treatment delivery during crises need to be re‐evaluated, because treatment interruptions and delays are expected to affect patient outcomes in this otherwise largely curable disease.

The response to the coronavirus disease 2019 (COVID‐19) pandemic has led to significant alterations in access to care for children with cancer. Interventions are needed to mitigate the effects on life‐threatening diseases requiring immediate and uninterrupted therapy, such as childhood cancer.

Clinical Prognostic Factors and Outcome in Pediatric Osteosarcoma: Effect of Delay in Local Control and Degree of Necrosis in a Multidisciplinary Setting in Lebanon

PURPOSE

Outcomes in pediatric osteosarcoma have dramatically improved over the past few decades, with overall survival rates of 70% and 30% for patients with localized and metastatic disease, respectively.

PATIENTS AND METHODS

We retrospectively reviewed clinical characteristics and outcomes of 38 patients treated between 2001 and 2012 at a single institution in Lebanon. All patients received a uniform three-drug chemotherapy regimen consisting of cisplatin, doxorubicin, and methotrexate. Ifosfamide and etoposide were added to the adjuvant treatment regimen in case of metastatic disease and/or poor degree of tumor necrosis (< 90%).

RESULTS

After a median follow-up of 61 months (range, 8 to 142 months), patients with localized disease had 5-year overall and event-free survival rates of approximately 81% and 68%, respectively, whereas for metastatic disease, they were approximately 42%. The most common primary site was the long bones around the knee (n = 34; 89.5%). Six patients (15.8%) had metastatic disease to lungs, and three (7.9%) had synchronous multifocal bone disease with lung metastases. Adverse prognostic factors included nonlower extremity sites, metastasis, poor degree of necrosis, and delay of more than 4 weeks in local control. In bivariable analysis, only degree of necrosis was a prognostic predictor for survival and disease recurrence.

CONCLUSION

Treatment of pediatric osteosarcoma in a multidisciplinary cancer center in Lebanon resulted in survival similar to that in developed countries. Delay in local control was associated with worse outcome. The only statistically significant inferior outcome predictor was poor degree of necrosis at the time of local control.

Cerebral sinus venous thrombosis during childhood acute lymphoblastic leukemia therapy: Risk factors and management

BACKGROUND

Cerebral sinus venous thrombosis (CSVT) is a rare but serious complication of childhood acute lymphoblastic leukemia (ALL) therapy. No available consensus exists regarding its risk factors and appropriate management due to the rarity of cases.

PROCEDURES

Out of 209 ALL patients aged 1-21 years treated at the Children's Cancer Center of Lebanon between May 2002 and May 2015, 13 developed CSVT during therapy. Patient characteristics, clinical management, and outcomes were studied.

RESULTS

The incidence of CSVT was 6.2% (95% confidence interval [CI]: 3.4-10.4). Using univariate analysis, increased risk of CSVT was observed with age >10 years (odds ratio [OR]: 3.56, 95% CI: 1.13-11.2), T-cell immunophenotype (OR: 4.14, 95% CI: 1.16-14.7), and intermediate/high risk disease (OR: 3.4, 95% CI: 1.03-11.7). The only statistically significant risk factor by multivariate analysis was the treatment as per the intermediate-/high-risk protocol (HR: 15.6, 95% CI: 1.43-171.3). Most cases (77%) occurred in the postinduction phases of treatment while receiving a combination of asparaginase and dexamethasone rather than prednisone. Treatment with low molecular weight heparin (LMWH) for a minimum of 3 months and until significant radiological improvement is observed resulted in 100% survival rate. All but one patient had complete neurological recovery.

CONCLUSIONS

CSVT is an important complication of childhood ALL therapy. Postinduction combined asparaginase and dexamethasone intensive treatment for intermediate-/high-risk patients was the most important risk factor. Treatment with LMWH for a minimum of 3 months, and until asparginase therapy is over, with major radiological improvement seems to be effective and feasible.

Statistically optimized ceftriaxone sodium biotransformation through Achromobacter xylosoxidans strain Cef6: an unusual insight for bioremediation

The present study underlines a unique promising approach toward efficient biotransformation of ceftriaxone sodium (Ceftx), a highly frequent prescribed cephalosporin antibiotic, by a newly bacterium namely Achromobacter xylosoxidans strain Cef6 isolated from Ceftx contaminated raw materials in pharmaceutical industries. A three step sequential statistical-mathematical approach (Plackett-Burman design [PBD], Central Composite Design [CCD], and ridge-canonical analyses) was anticipated to optimize the biotransformation process. Ceftx concentration and medium volume: bottle volume ratio, two key determinants, significantly (p < 0.05) affected the process outcome deduced by regression analysis of PBD' data. CCD and ridge-canonical analyses localized the optimal levels of Ceftx concentration and medium volume: 250 ml bottle volume ratio to be 0.39 and 7.973 g Ceftx/L modified tryptic soy broth achieving Ceftx biotransformation (100%) after 39 h under aerobic static conditions at 30 °C, irrespectively deduced via HPLC analysis. Impressively, only one of five Ceftx byproducts was detected by the end of the biotransformation process. To the best of authors' knowledge, this is the first report addressing a detailed study regarding efficient biotransformation of Ceftx by single bacterium not bacterial consortium under aerobic conditions. Present data would greatly encourage applying this approach for decontamination of some Ceftx contaminated environmental sites.

Fludarabine-based reduced intensity regimen for matched related donor hematopoietic stem cell transplantation in acquired severe aplastic anemia

Different conditioning regimens have been evaluated in matched-related donor allogeneic hematopoietic stem cell transplantation (allo-HSCT) for acquired severe aplastic anemia (SAA) with varying results. In this manuscript, we report our experience with fludarabine (120mg/m²), very low dose cyclophosphamide (1200mg/m²) and antithymocyte globulin (7.5mg/kg). Low dose total body irradiation (2Gy) was added to the conditioning regimen for patients older than 15 years. Nineteen patients (median age 23years) underwent transplant between 2008 and 2015. The majority (89%) were younger than 40 years. Stem cell source was BM (n=11) or PBSC (n=8). GvHD prophylaxis consisted of cyclosporine and either a short course of methotrexate (n=9) or mycophenolate mofetil (n=10). Eighteen (94.7%) patients achieved sustained engraftment. The median times to neutrophil and platelet engraftments were 19 (range: 14-34) and 17.1 (range: 12-25) days, respectively. The day-30 cumulative incidence of neutrophil and platelet engraftment was 89.4% and 94.7%, respectively. No secondary graft rejection was observed. The 1-year cumulative incidence of aGvHD (grade II-IV) and cGvHD was 11.7% and 0%, respectively. The 2-year GvHD-free survival rate was 78.6% (95% CI: 52.5-91.4%). Fludarabine-based reduced intensity regimen for MRD allo-HSCT in SAA compares favorably to other available regimens. This regimen deserves further investigations with larger cohort of patients.

NUDT15 and TPMT genetic polymorphisms are related to 6-mercaptopurine intolerance in children treated for acute lymphoblastic leukemia at the Children's Cancer Center of Lebanon

BACKGROUND

Interindividual variability in thiopurine-related toxicity could not be completely explained by thiopurine S-methyltransferase (TPMT) polymorphisms, as a number of patients who are homozygous wild type or normal for TPMT still develop toxicity that necessitates 6-mercaptopurine (MP) dose reduction or protocol interruption. Recently, few studies reported on an inherited nucleoside diphosphate-linked moiety X motif 15 (NUDT15) c.415C>T low-function variant that is associated with decreased thiopurine metabolism and leukopenia in childhood acute lymphoblastic leukemia (ALL) and other diseases.

PROCEDURES

The aim of this study is to measure the frequency of TPMT and NUDT15 polymorphisms and assess whether they are predictors of MP intolerance in children treated for ALL. One hundred thirty-seven patients with ALL of whom 121 were Lebanese were evaluated. MP dose intensity was calculated as the ratio of the tolerated MP dose to planned dose during continuation phase to maintain an absolute neutrophil count (ANC) dose above 300 per μl.

RESULTS

One patient was NUDT15 heterozygous TC and tolerated only 33.33% of the planned MP dose, which was statistically significantly different from the median-tolerated MP dose intensity of the rest of the cohort (76.00%). Three patients had the TPMT*3A haplotype and tolerated 40.00-66.66% of the planned MP dose, which was also statistically significantly different from the rest of the cohort.

CONCLUSIONS

This is the first report on the association of TPMT and NUDT15 polymorphisms with MP dose intolerance in Arab patients with ALL. Genotyping for additional polymorphisms may be warranted for potential gene/allele-dose effect.

Metal Ion Removal from Wastewaters by Sorption on Activated Carbon, Cement Kiln Dust, and Sawdust

This study assessed the efficiency of activated carbon, cement kiln dust (CKD), and sawdust for the removal of cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn) from aqueous solutions under mono-metal and competitive sorption systems and the removal of Cd, Cu, and Zn from different industrial wastewaters. Batch equilibrium experiments were conducted in a mono-metal and competitive sorption system. The efficiency of the sorbents in the removal of Cd, Cu, and Zn from industrial wastewaters was also investigated. Cement kiln dust expressed the highest affinity for the metals followed by activated carbon and sawdust. Competition among the metals changed their distribution coefficient (Kd) with the sorbents. Sorption of Pb and Cu was higher than Cd and Zn. The average metal removal from the wastewaters varied from 74, 61, and 60% for Cd, Cu, and Zn, respectively, to nearly 100%. The efficiencies of CKD and activated carbon in removing metals were higher than sawdust, suggesting their potential as low-cost sorbents for the removal of toxic metals from wastewaters.

Heavy metals removal from aqueous solutions and wastewaters by using various byproducts

Water contamination with heavy metals (HM) represents a potential threat to humans, animals and plants, and thus removal of these metals from contaminated waters has received increasing attention. The present study aimed to assess the efficiency of some low cost sorbents i.e., chitosan (CH), egg shell (ES), humate potassium (HK), and sugar beet factory lime (SBFL) for removal of cadmium (Cd), copper (Cu), lead (Pb) and zinc (Zn) from wastewaters. For this purpose batch equilibrium experiments were conducted with aqueous solutions containing various concentrations of the metals and sorbents in a mono-metal and competitive sorption system. Sorption isotherms were developed, and sorption parameters were determined. The potential applicability of the tested sorbents in the removal of Cd, Cu, and Zn from contaminated wastewaters was also investigated by equilibrating different sorbents and water ratios. Chitosan expressed the highest affinity for the metals followed by SBFL, ES, and HK. Nearly 100% of the metals were removed from aqueous solutions with the lowest initial metal concentrations by the sorbents especially CH and SBFL. However, the sorption efficiency decreased as the initial metal concentrations increased. Competition among the four metals changed significantly their distribution coefficient (Kd) values with the sorbents. The selectivity sequence of the metals was: Pb > Cu > Zn > Cd. The metal removal from the wastewaters varied from 72, 69, and 60 to nearly 100% for Cd, Cu and Zn, respectively. The efficiency of the studied byproducts in removing metals from the wastewaters differed based on the source of contamination and metal concentrations. Cadmium removal percentages by HK and CH were higher than SBFL and ES. The HK and CH exhibited the highest removal percentage of Cu from water with high concentrations. The SBFL and ES revealed the highest removal percentage of Zn from water with high concentrations. The results, demonstrate a high potential of CH, SBFL, HK, and ES for the remediation of HM contaminated wastewaters.

Citric acid production by a novel Aspergillus niger isolate: I. Mutagenesis and cost reduction studies

Ultraviolet-irradiation (UV), ethyl methane sulfonate (EMS) and acridine orange (AO) were used to induce citric acid overproduction mutations in Aspergillus niger UMIP 2564. Among 15, eight of the mutant derivatives, were improved with respect to citric acid production from sucrose in batch cultures. Maximum product yield (60.25%) was recorded by W5, a stable UV mutant, with approximately 3.2-fold increase when compared to the parental wild type strain. In terms of the kinetic parameters for batch fermentation processes, the mutation doubled the specific substrate uptake rate and achieved 4.5- and 7.5-fold improvements in citric acid productivity and specific productivity, respectively. For reduction of the fermentation medium cost, corn steep liquor and calcium phosphate pre-treated beet molasses were successfully used as substituents of nitrogen and carbon sources in the growth medium, respectively. These medium substitutions resulted in a W5 citric acid fermentation culture with a product yield of 74.56%.

Citric acid production by a novel Aspergillus niger isolate: II. Optimization of process parameters through statistical experimental designs

In this work, sequential optimization strategy, based on statistical designs, was employed to enhance the production of citric acid in submerged culture. For screening of fermentation medium composition significantly influencing citric acid production, the two-level Plackett-Burman design was used. Under our experimental conditions, beet molasses and corn steep liquor were found to be the major factors of the acid production. A near optimum medium formulation was obtained using this method with increased citric acid yield by five-folds. Response surface methodology (RSM) was adopted to acquire the best process conditions. In this respect, the three-level Box-Behnken design was applied. A polynomial model was created to correlate the relationship between the three variables (beet molasses, corn steep liquor and inoculum concentration) and citric acid yield. Estimated optimum composition for the production of citric acid is as follows pretreated beet molasses, 240.1g/l; corn steep liquor, 10.5g/l; and spores concentration, 10(8)spores/ml. The optimum citric acid yield was 87.81% which is 14 times than the basal medium. The five level central composite design was used for outlining the optimum values of the fermentation factors initial pH, aeration rate and temperature on citric acid production. Estimated optimum values for the production of citric acid are as follows initial pH 4.0; aeration rate, 6500ml/min and fermentation temperature, 31.5 degrees C.

Amplification of the Escherichia coli lacZ gene in Bacillus subtilis and its expression on a by-product growth medium

A Bacillus subtilis wild type strain and a kinA (spoIIJ) isogenic mutant were compared as hosts for the expression of the Escherichia coli beta-galactosidase gene, lacZ, driven by the B. subtilis aprE promoter in a chromosomal system. The 2 x SG sporulation formula, with some modifications, was used as a basal medium. The specific activity values recorded by the mutant strain at the stationary phase were markedly higher than those achieved by the wild type host. Exposure of the cells to increasing levels of chloramphenicol resulted in significant amplifications of the lacZ region. Gene copy numbers of 19 and 11 were estimated in the amplified wild type and kinA strains, respectively, with high segregational stability records. The magnitude of beta-galactosidase over-expression was dependent on, and roughly proportional to antibiotic resistance levels. Among five examined by-products, a 2.3-times diluted concentration of neutralized cheese whey was successfully used as a sole medium component for over-expression of the recombinant beta-galactosidase gene in B. subtilis.

Application of the response surface methodology for optimizing the activity of an aprE-driven gene expression system in Bacillus subtilis

The major targets for improvement of recombinant expression systems in microbial cells are gene dosage, transcriptional control machinery and, to some extent, translation. Here we show that optimization of fermentation conditions by applying statistically designed, multifactorial experiments offers an additional method for potential enhancement of gene expression systems. A chromosomally encoded fusion between the Bacillus subtilis aprE regulatory region and the E. coli lacZ gene carried by the B. subtilis host cells was used. The 2 x SG sporulation medium was used as a basal medium. Among the 11 fermentation factors we examined, the most significant variables influencing beta-galactosidase expression were statistically elucidated for optimization and included peptone, MgSO4.7H2O, and KCl. The optimum concentrations of these variables were predicted by using a second-order polynomial model fitted to the results obtained by applying the Box-Behnken design, a response surface method. Calculated optimum concentrations were predicted to confer a maximum yield of 2,423.5 beta-galactosidase specific activity units. A verification experiment performed under optimal conditions yielded 96% of the predicted specific activity value with an increase by a factor of almost 5 compared with the results obtained under basal conditions.

Effect of nutrients on alginate synthesis in Azotobacter vinelandii and characterization of the produced alginate

The role of nutrients on alginate production by Azotobacter vinelandii was studied in batch cultures. The largest amount of bacterial alginate was obtained in presence of: 0.3 g/l MgSO4.7H2O. 0.4 g/l NaCl, 42 mg/l CaCl2.2H2O,.4 mg/l KH2PO4, 16 mg/l K2HPO4, 2.5 mg/l FeSO4.7H2O, 2.9 mg/l H3BO3, 2 mg/l ZnSO4.7H2O, 2 mg/l Na2MoO4.2H2O, 0.3 mg/l CuSO4.5H2O, 0.2 mg/l MnCl2.4H2O. Alginate production was not enhanced by natural additives or inducing agents, except for acetate, which increased alginate yield. The pure alginate contained 0.36% ash and 0.4% protein. It is similar to algal alginate, but it has an extra acetyl group. It contains 69.5% M-M block, 27.5% M-G block and 3% G-G block.

Riboflavin production by Aspergillus terreus from beet-molasses

Aspergillus terreus was used for riboflavin (vitamin B2) production in a medium containing beet molasses as the sole carbon source. Growth and the vitamin production of the fungus were markedly affected by the composition of the culture medium. A maximum riboflavin yield was achieved at the late exponential growth phase (16 day-old cultures) in the presence of (g/l): centrifuged beet-molasses, 90; L-asparagine, 1; MgSO4.7H2O, 0.5; K2HPO4/kH2PO4 (1:1), 5; and the medium initially adjusted to pH 8.

Some nutritional requirements of a mixed culture transforming Reichstein's compound S into prednisolone

Reichstein's compound S was successfully converted to prednisolone in a single-step fermentation using a mixed culture of Curvularia lunata and Mycobacterium smegmatis. Introducing additional medium at the time of bacterial inoculation and increasing the M. smegmatis inoculum to 8% were necessary for maximal dehydrogenation of cortisol to prednisolone (86%). However, beef extract, corn-steep solids, and malt extract were inhibitory to the dehydrogenase activity and stimulatory to hydroxylase. Of the vitamins tested, nicotinic acid and riboflavin at 0.2 and 1.13 mg/L, respectively, resulted in maximum transformation of Reichstein's compound S (100%) and optimized prednisolone yields (92%) in the mixed culture. The trace elements present in the medium were sufficient for maximal transformation, and there was no need for an exogenous supply. Addition of ATP, sodium acetate, and NAD inhibited the dehydrogenation reaction.

Single cell protein production from beet pulp by mixed culture

Different mixed cultures of Trichoderma reesei and a yeast were cultivated on beet pulp (BP)-containing medium. T. reesei and Kluyveromyces marxianus offered a combination that gave high SCP yields (51%) and efficiently converted BP into proteins (39.4%). The yeast extract in the basal medium could be substituted and the BP level multiplicated from 2 to 4% upon using mixed culture of T. reesei and K. marxianus. Under these conditions the protein yields reached to a maximum value of 54% and highest efficiency of BP conversion into proteins (41.8%). The obtained protein proved to contain all essential amino acids, which compared favourably with those of the FAO guideline and soy bean oil meal.

Utilization of beet molasses for sterol production by some moulds

Different moulds were cultivated in beet molasses (BM)-containing medium. Penicillium crustosum Thom was superior to the other moulds in total sterols production (4% on dry weight basis), efficiency of convertibility of the BM sugars to sterols (2%), total lipids (19.4%) and unsaponified lipids (13.4%). The treatment of BM with H2SO4- followed by centrifugation allowed maximum fermentation yields. The highest unsaponified lipids (16.5%) and total sterols level (7.4%) were obtained with a medium composed of (g/1): NaNO3, 3; K2HPO4, 3; MgSO4.7H2O, 1.5; K2SO4, 0.11; ZnSO4.7H2O, 0.05; FeCl3.6H2O, 0.16; H2SO4-treated BM, 60. Maximal sterol yields (8.4%) and high growth rate were achieved at the accelerated growth phase (8 days old cultures), when the initial pH value of the medium was adjusted to 7.0.