Metformin as a potential disease-modifying drug in osteoarthritis: a systematic review of pre-clinical and human studies.

OBJECTIVE: Osteoarthritis causes significant pain and disability with no approved disease-modifying drugs. We systematically reviewed the evidence from both pre-clinical and human studies for the potential disease-modifying effect of metformin in osteoarthritis. METHODS: Ovid Medline, Embase and CINAHL were searched between inception and June 2021 using MeSH terms and key words to identify studies examining the association between metformin use and outcome measures related to osteoarthritis. Two reviewers performed the risk of bias assessment and 3 reviewers extracted data independently. Qualitative evidence synthesis was performed. This systematic review is registered on PROSPERO (CRD42021261052 and CRD42021261060). RESULTS: Fifteen (10 pre-clinical and 5 human) studies were included. Most studies (10 pre-clinical and 3 human) assessed the effect of metformin using knee osteoarthritis models. In pre-clinical studies, metformin was assessed for the effect on structural outcomes (n = 10); immunomodulation (n = 5); pain (n = 4); and molecular pathways of its effect in osteoarthritis (n = 7). For human studies, metformin was evaluated for the effect on structural progression (n = 3); pain (n = 1); and immunomodulation (n = 1). Overall, pre-clinical studies consistently showed metformin having a chondroprotective, immunomodulatory and analgesic effect in osteoarthritis, predominantly mediated by adenosine monophosphate-activated protein kinase activation. Evidence from human studies, although limited, was consistent with findings in pre-clinical studies. CONCLUSION: We found consistent evidence across pre-clinical and human studies to support a favourable effect of metformin on chondroprotection, immunomodulation and pain reduction in knee osteoarthritis. Further high-quality clinical trials are needed to confirm these findings as metformin could be a novel therapeutic drug for the treatment of osteoarthritis.

Activation tagging in indica rice identifies ribosomal proteins as potential targets for manipulation of water-use efficiency and abiotic stress tolerance in plants.

We have generated 3900 enhancer-based activation-tagged plants, in addition to 1030 stable Dissociator-enhancer plants in a widely cultivated indica rice variety, BPT-5204. Of them, 3000 were screened for water-use efficiency (WUE) by analysing photosynthetic quantum efficiency and yield-related attributes under water-limiting conditions that identified 200 activation-tagged mutants, which were analysed for flanking sequences at the site of enhancer integration in the genome. We have further selected five plants with low Δ13 C, high quantum efficiency and increased plant yield compared with wild type for a detailed investigation. Expression studies of 18 genes in these mutants revealed that in four plants one of the three to four tagged genes became activated, while two genes were concurrently up-regulated in the fifth plant. Two genes coding for proteins involved in 60S ribosomal assembly, RPL6 and RPL23A, were among those that became activated by enhancers. Quantitative expression analysis of these two genes also corroborated the results on activating-tagging. The high up-regulation of RPL6 and RPL23A in various stress treatments and the presence of significant cis-regulatory elements in their promoter regions along with the high up-regulation of several of RPL genes in various stress treatments indicate that they are potential targets for manipulating WUE/abiotic stress tolerance.

In planta transformation of pigeon pea: a method to overcome recalcitrancy of the crop to regeneration in vitro.

Development of transgenics in pigeon pea remains dogged by poor plant regeneration in vitro from transformed tissues and low frequency transformation protocols. This article presents a non-tissue culture-based method of generating transgenic pigeon pea (Cajanus cajan (L.) Millisp.) plants using Agrobacterium-Ti plasmid-mediated transformation system. The protocol involves raising of whole plant transformants (T0 plants) directly from Agrobacterium-infected young seedlings. The plumular and intercotyledonary meristems of the seedling axes are targeted for transformation. The transformation conditions optimized were, pricking of the apical and intercotyledonary region of the seedling axes of two-day old germinating seedlings with a sewing needle, infection with Agrobacterium (LBA4404/pKIWI105 carrying uid A and npt II genes) in Winans' AB medium that was added with wounded tobacco leaf extract, co-cultivation in the same medium for 1h and transfer of seedlings to soilrite for further growth and hardening and subsequent transfer of seedlings to soil in pots in the greenhouse. Out of the 22-25 primary transformants that survived infection-hardening treatments from each of the three experiments, 15 plants on the average established on the soil under greenhouse conditions, showed slow growth initially, nevertheless grew as normal plants, and flowered and set seed eventually. Of the several seeds harvested from all the T0 plants, six hundred were sown to obtain progeny (T1) plants and 350 of these were randomly analysed to determine their transgenic nature. PCR was performed for both gus (uid A) and npt II genes. Forty eight of the 350 T1 plants amplified both transgenes. Southern blot analysis substantiated the integration and transmission of these genes. The protocol ensured generation of pigeon pea transgenic plants with considerable ease in a short time and is applicable across different genotypes/cultivars of the crop and offers immense potential as a supplemental or an alternative protocol for generating transgenic plants of difficult-to-regenerate pigeon pea. Further, the protocol offers the option of doing away with a selection step in the procedure and so facilitates transformation, which is free of marker genes.

Leaf cuticular wax amount and crystal morphology regulate post-harvest water loss in mulberry (Morus species).

Mulberry leaves are the sole source of food for silkworms (Bombyx mori), and moisture content of the detached leaves fed to silkworms determines silkworm growth and cocoon yield. Since leaf dehydration in commercial sericulture is a serious problem, development of new methods that minimize post-harvest water loss are greatly needed. In the present study, variability in moisture retention capacity (MRC, measured as leaf relative water content after one to 5 h of air-drying) was examined by screening 290 diverse mulberry accessions and the relationship between MRC and leaf surface (cuticular) wax amount was determined. Leaf MRC varied significantly among accessions, and was found to correlate strongly with leaf wax amount. Scanning electron microscopic analysis indicated that leaves having crystalline surface waxes of increased facet size and density were associated with high MRC accessions. Leaf MRC at 5 h after harvest was not related to other parameters such as specific leaf weight, and stomatal frequency and index. This study suggests that mulberry accessions having elevated leaf surface wax amount and crystal size and density exhibit reduced leaf post-harvest water loss, and could provide the foundation for selective breeding of improved cultivars.

Kinetics of serum immunoglobulin isotype response in experimental bovine tropical fasciolosis.

The present communication reports on the kinetics of immunoglobulin isotype response in Fasciola gigantica infected bovine calves. Fifteen Holstein-Friesian cross-bred male calves were assigned to 3 groups (Gr) of 5 calves each and infected with 4-month (Gr-A) and 16-month-old (Gr-B) F. gigantica metacercariae (n=400), respectively, while Gr-C calves served as uninfected control. Infection was terminated by treating the animals with triclabendazole on 28 weeks post-infection (WPI). Sera were collected on 0, 4, 10 and 14 days post-infection (DPI) and subsequently at weekly interval up to 32 WPI. The immunoglobulin isotype response was analyzed by ELISA, using anion exchange purified antigen fraction. An IgG response against F. gigantica infection was evoked by 3 and 2 WPI in animals of Gr-A and Gr-B, respectively with peak antibody response at 13 WPI. Elicitation of an early IgG1 response by 10 and 14 DPI but a delayed IgG2 response at 6 and 4 WPI, in animals of Gr-A and Gr-B, respectively was recorded. An early IgM response was evoked by 10 and 14 DPI and the level peaked at 13 and 12 WPI, with no detectable level at 21 and 15 WPI in animals of Gr-A and Gr-B, respectively. IgA response was elicited at 4 WPI in both the groups and showed the highest titre at 25 and 27 WPI in animals of Gr-A and Gr-B, respectively. Present study indicated an early and predominant response of IgG1, with concurrent expression of delayed and weak IgG2 in calves experimentally infected with F. gigantica.

A stress-responsive gene from groundnut, Gdi-15, is homologous to flavonol 3-O-glucosyltransferase involved in anthocyanin biosynthesis.

Stress-tolerant crops are expected to express genes not normally expressed in susceptible crops. We have used desiccation stress coupled with high light intensity to identify groundnut as a relatively tolerant crop. Stress-responsive genes (Gdi, Groundnut Desiccation Induced) were cloned by subtractive hybridisation. The sequence of Gdi-15 shows homology to flavonol 3-O-glucosyltransferases, which are involved in anthocyanin biosynthesis. Gdi-15 transcripts increase markedly in response to stress, suggestive of a role in stress tolerance.