An exploratory investigation of the CSF metabolic profile of HIV in a South African paediatric cohort using GCxGC-TOF/MS

INTRODUCTION

 Because cerebrospinal fluid (CSF) samples are difficult to obtain for paediatric HIV, few studies have attempted to profile neurometabolic dysregulation.

AIM AND OBJECTIVE

The aim of this exploratory study was to profile the neurometabolic state of CSF from a South African paediatric cohort using GCxGC-TOF/MS. The study included 54 paediatric cases (< 12 years), 42 HIV-negative controls and 12 HIV-positive individuals.

RESULTS

The results revealed distinct metabolic alterations in the HIV-infected cohort. In the PLS-DA model, 18 metabolites significantly discriminated between HIV-infected and control groups. In addition, fold-change analysis, Mann-Whitney U tests, and effect size measurements verified these findings. Notably, lactose, myo-inositol, and glycerol, although not significant by p-value alone, demonstrated practical significance based on the effect size.

CONCLUSIONS

This study provided valuable insights on the impact of HIV on metabolic pathways, including damage to the gut and blood-brain barrier, disruption of bioenergetics processes, gliosis, and a potential marker for antiretroviral therapy. Nevertheless, the study recognized certain constraints, notably a limited sample size and the absence of a validation cohort. Despite these limitations, the rarity of the study's focus on paediatric HIV research underscores the significance and unique contributions of its findings.

Slurry phase biodegradation of heavy oily sludge and evidence of asphaltene biotransformation

Oily sludge management is a global environmental concern due to its hazardous nature. Oily sludge obtained from a refinery in India had 19-21% oil content. The oil was highly enriched in the asphaltene fraction. Slurry phase biodegradation of this oily sludge in presence of a 3-membered bacterial consortium was optimized in presence of Triton X-100 to increase the bioavailability of hydrocarbons. Triton X-100 at 4 times the critical micelle concentration (CMC) showed the highest degradation where oil removal of 53.1% was achieved from a 10% sludge slurry over 90 days. GCxGC analysis of n-alkanes present in the oily sludge after the biodegradation study showed an increase in the lower n-alkanes, i.e., dodecane and tridecane over the first 30 days, whereas the higher n-alkanes were removed to a much higher extent. Heptadecane showed the maximum extent of degradation with 94.9% removal in 90 days and an initial degradation rate of 0.079 day^-1. The, maximum rate of degradation was observed for pentacosane (0.083 day^-1) with 93.7% removal in 90 days. The increase in the lower n-alkanes may be attributed to biotic transformation of the asphaltene fraction which was also confirmed through FTIR and pyrolysis GCxGC analysis. Biodegradation was found to cause changes in the pyrolysis product of asphaltenes where four and three-ring pyrolysis products decreased while the one and two-ring pyrolysis products increased. In presence of the consortium asphaltene removal over 90 days was 12% whereas only 0.4% removal was obtained in the abiotic controls.

Characterization and biodegradability assessment of water-soluble fraction of oily sludge using stir bar sorptive extraction and GCxGC-TOF MS

Percolation of water through oily sludge during storage and handling of the sludge can cause soil and groundwater contamination. In this study, oily sludge from a refinery was equilibrated with water to obtain the water-soluble fraction (WSF) of oily sludge. The WSF had dissolved organic carbon (DOC) of 166 mg/L. Human cell line-based toxicity assay revealed IC₅₀ of 41 mg/L indicating its toxic nature. The predominant compounds in WSF of oily sludge included isomers of methyl, dimethyl and trimethyl quinolines and naphthalenes along with phenol derivatives and other polynuclear aromatic hydrocarbons (PAHs). Biodegradation of WSF of oily sludge was studied using a consortium of Rhodococcus ruber, Bacillus sp. and Bacillus cereus isolated from the refinery sludge. The consortium of the three strains resulted in 70% degradation over 15 days with a first-order degradation rate of 0.161 day^-1. Further analysis of the WSF was performed using the stir-bar sorptive extraction (SBSE) followed by GCxGC-TOF MS employing a PDMS Twister. The GCxGC analysis showed that Bacillus cereus was capable of degrading the quinoline, phenol and naphthalene derivatives in WSF of oily sludge at a faster rate compared to pyridine and benzoquinoline derivatives. Quinoline, phenol, biphenyl, naphthalene, pyridine and benzoquinolines derivatives in the WSF of oily sludge were reduced by 87%, 92%, 88%, 77%, 40% and 62%, respectively with respect to the controls. The WSF of oily sludge contained, n-alkanes, ranging from n-C12 to n-C18 which were removed within 2 days of biodegradation.