Pooled testing for COVID-19 diagnosis by real-time RT-PCR: A multi-site comparative evaluation of 5- & 10-sample pooling.

BACKGROUND & OBJECTIVES: Public health and diagnostic laboratories are facing huge sample loads for COVID-19 diagnosis by real-time reverse transcription-polymerase chain reaction (RT-PCR). High sensitivity of optimized real-time RT-PCR assays makes pooled testing a potentially efficient strategy for resource utilization when positivity rates for particular regions or groups of individuals are low. We report here a comparative analysis of pooled testing for 5- and 10-sample pools by real-time RT-PCR across 10 COVID-19 testing laboratories in India. METHODS: Ten virus research and diagnostic laboratories (VRDLs) testing for COVID-19 by real-time RT-PCR participated in this evaluation. At each laboratory, 100 nasopharyngeal swab samples including 10 positive samples were used to create 5- and 10-sample pools with one positive sample in each pool. RNA extraction and real-time RT-PCR for SARS-CoV-2-specific E gene target were performed for individual positive samples as well as pooled samples. Concordance between individual sample testing and testing in the 5- or 10-sample pools was calculated, and the variation across sites and by sample cycle threshold (Ct) values was analyzed. RESULTS: A total of 110 each of 5- and 10-sample pools were evaluated. Concordance between the 5-sample pool and individual sample testing was 100 per cent in the Ct value ≤30 cycles and 95.5 per cent for Ctvalues ≤33 cycles. Overall concordance between the 5-sample pooled and individual sample testing was 88 per cent while that between 10-sample pool and individual sample testing was 66 per cent. Although the concordance rates for both the 5- and 10-sample pooled testing varied across laboratories, yet for samples with Ct values ≤33 cycles, the concordance was ≥90 per cent across all laboratories for the 5-sample pools. INTERPRETATION & CONCLUSIONS: Results from this multi-site assessment suggest that pooling five samples for SARS-CoV-2 detection by real-time RT-PCR may be an acceptable strategy without much loss of sensitivity even for low viral loads, while with 10-sample pools, there may be considerably higher numbers of false negatives. However, testing laboratories should perform validations with the specific RNA extraction and RT-PCR kits in use at their centres before initiating pooled testing.

Standardized extract of Withania somnifera (Ashwagandha) markedly offsets rotenone-induced locomotor deficits, oxidative impairments and neurotoxicity in Drosophila melanogaster.

Withania somnifera (Ashwagandha, WS) or Indian ginseng possesses multiple pharmacological properties which are mainly attributed to the active constituents, withanolides. Despite its extensive usage as a memory enhancer and a nerve tonic, few attempts have been made to ascertain its usage in the management of Parkinson's disease. In the present study, we investigated the neuroameliorative effects of WS in a rotenone (ROT) model of Drosophila melanogaster (Oregon-K). Initially, we ascertained the ability of WS-enriched diet (0-0.05 %) to protect against ROT induced lethality and locomotor phenotype in adult male flies. Further, employing a co-exposure paradigm, we investigated the propensity of WS to offset ROT-induced oxidative stress, mitochondrial dysfunctions and neurotoxicity. WS conferred significant protection against ROT-induced lethality, while the survivor flies exhibited improved locomotor phenotype. Biochemical investigations revealed that ROT-induced oxidative stress was significantly diminished by WS enrichment. WS caused significant elevation in the levels of reduced GSH/non-protein thiols. Furthermore, the altered activity levels of succinate dehydrogenase, MTT, membrane bound enzymes viz., NADH-cytochrome-c reductase and succinate-cytochrome-c reductase were markedly restored to normalcy. Interestingly, ROT-induced perturbations in cholinergic function and depletion in dopamine levels were normalized by WS. Taken together these data suggests that the neuromodulatory effect of WS against ROT- induced neurotoxicity is probably mediated via suppression of oxidative stress and its potential to attenuate mitochondrial dysfunctions. Our further studies aim to understand the underlying neuroprotective mechanisms of WS and withanolides employing neuronal cell models.

Neuropharmacological Properties of Withania somnifera - Indian Ginseng: An Overview on Experimental Evidence with Emphasis on Clinical Trials and Patents.

BACKGROUND: Owing to the increasing aged population globally, disorders and diseases of the CNS are anticipated to increase and profoundly impact the health care. As these neurodegenerative diseases (NDD) are complex, multifactorial and do not have identified etiological factors, unfortunately, drugs developed for the purpose have not met with the expected success. Hence, there has been a constant demand for the development of natural therapeutic adjuvants which are safe and possess the potential to attenuate multiple pathways. METHODS: Numerous herbal/natural products have been used as therapeutics in Ayurvedic system of medicine to treat NDD and other memory-related disorders. Withania somnifera (Ashwagandha, WS), popularly called as "Indian Ginseng" is one such plant which possesses a variety of beneficial neuropharmacological properties. In this review, we have attempted to review critically the existing literature and patents related to the neuroprotective efficacy of WS roots and the underlying mechanism/s. RESULTS: Standardized extracts of Withania somnifera (WS) have been demonstrated to possess multidimensional neuromodulatory effects both in vitro and animal models. The spectrum of effects evidenced comprises of attenuation of oxidative damage by enhancing the antioxidant defense system with concomitant enhancement of the expression of marker proteins responsible for growth, differentiation and communication of neural cells. Specific effects of WS are attributable to its potential to modulate neurotrophic factors, cytoskeletal elements, cell adhesion molecules and synaptic proteins. CONCLUSION: Generation of new data by employing systematic contemporary approaches such as bioinformatics, molecular docking studies, identification of specific gene targets and epigenetic regulation would provide the necessary impetus to validate fully the neurotherapeutic potential of the phytochemicals derived from WS. More importantly, well-designed clinical trials are required to exploit the neuromodulatory propensity of WS extract/bioactives in specific neurodegenerative diseases such as AD and PD.