Raman spectroscopy technology to monitor the carotenoids in skin of thalassemia patients: a novel non-invasive tool relating oxidative stress with iron burden

A meta-analysis of studies examining associations between resonance Raman spectroscopy-assessed skin carotenoids and plasma carotenoids among adults and children

CONTEXT

No meta-analyses appeared to have been conducted to examine overall correlations between resonance Raman spectroscopy (RRS)-assessed skin carotenoids and plasma/serum carotenoids.

OBJECTIVE

To review the available literature and quantify the association between RRS-assessed skin carotenoids and plasma/serum carotenoids via a meta-analysis of observational studies.

DATA SOURCES

To identify relevant publications, we searched the PubMed, Embase, CINAHL, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, ProQuest, and Scopus databases in April 2020 for items combining 3 concepts: Raman spectroscopy, skin, and plasma or serum.

DATA EXTRACTION

Criteria for inclusion were publication in a peer-reviewed journal between 1990 and 2020, available in English language, and results reported as a baseline Pearson correlation coefficient. In teams of 2, the researchers independently reviewed titles and abstracts of 2212 nonduplicate papers with initial screening yielding 62 papers for full-text review, of which 15 were deemed eligible for inclusion.

DATA ANALYSIS

A random-effects model in R (version 4.0.0) "meta" package was used to analyze the correlation between RRS-assessed skin and plasma/serum carotenoids. A subgroup analysis was conducted for studies involving adults and children, respectively.

CONCLUSIONS

The 15 studies included 1155 individuals: 963 adults and 192 children. One study included children and adults. The random-effects model yielded an overall correlation of 0.68 (95%CI, 0.61-0.74; I2 = 74%; P < 0.01). The results were similar when grouped by adults and children. Among 963 adults, the correlation in the random-effects model was 0.69 (95%CI, 0.61-0.75; I2 = 78%; P < 0.01). Among 192 children, the correlation in the random-effects model was 0.66 (95%CI, 0.52- 0.77; I2 = 55%; P = 0.06). Overall, there was a positive, statistically significant correlation between RRS-assessed skin carotenoids and plasma/serum carotenoids in a pooled meta-analysis of 15 studies.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO (record number 178835).

Identification of conserved genes linked to responses to abiotic stresses in leaves among different plant species

As a consequence of global climate change, certain stress factors that have a negative impact on crop productivity such as heat, cold, drought and salinity are becoming increasingly prevalent. We conducted a meta-analysis to identify genes conserved across plant species involved in (1) general abiotic stress conditions, and (2) specific and unique abiotic stress factors (drought, salinity, extreme temperature) in leaf tissues. We collected raw data and re-analysed eight RNA-Seq studies using our previously published bioinformatic pipeline. A total of 68 samples were analysed. Gene set enrichment analysis was performed using MapMan and PageMan whereas DAVID (Database for Annotation, Visualisation and Integrated Discovery) was used for metabolic process enrichment analysis. We identified of a total of 5122 differentially expressed genes when considering all abiotic stresses (3895 were upregulated and 1227 were downregulated). Jasmonate-related genes were more commonly upregulated by drought, whereas gibberellin downregulation was a key signal for drought and heat. In contrast, cold stress clearly upregulated genes involved in ABA (abscisic acid), cytokinin and gibberellins. A gene (non-phototrophic hypocotyl) involved in IAA (indoleacetic acid) response was induced by heat. Regarding secondary metabolism, as expected, MVA pathway (mevalonate pathway), terpenoids and alkaloids were generally upregulated by all different stresses. However, flavonoids, lignin and lignans were more repressed by heat (cinnamoyl coA reductase 1 and isopentenyl pyrophosphatase). Cold stress drastically modulated genes involved in terpenoid and alkaloids. Relating to transcription factors, AP2-EREBP, MADS-box, WRKY22, MYB, homoebox genes members were significantly modulated by drought stress whereas cold stress enhanced AP2-EREBPs, bZIP members, MYB7, BELL 1 and one bHLH member. C2C2-CO-LIKE, MADS-box and a homeobox (HOMEOBOX3) were mostly repressed in response to heat. Gene set enrichment analysis showed that ubiquitin-mediated protein degradation was enhanced by heat, which unexpectedly repressed glutaredoxin genes. Cold stress mostly upregulated MAP kinases (mitogen-activated protein kinase). Findings of this work will allow the identification of new molecular markers conserved across crops linked to major genes involved in quantitative agronomic traits affected by different abiotic stress.