Prion-Like Propagation of Post-Translationally Modified Tau in Alzheimer’s Disease: A Hypothesis

The microtubule-associated protein Tau plays a key role in the neuropathology of Alzheimer’s disease by forming intracellular neurofibrillary tangles. Tau in the normal physiological condition helps stabilize microtubules and transport. Tau aggregates due to various gene mutations, intracellular insults and abnormal post-translational modifications, phosphorylation being the most important one. Other modifications which alter the function of Tau protein are glycation, nitration, acetylation, methylation, oxidation, etc. In addition to forming intracellular aggregates, Tau pathology might spread in a prion-like manner as revealed by several in vitro and in vivo studies. The possible mechanism of Tau spread can be via bulk endocytosis of misfolded Tau species. The recent studies elucidating this mechanism have mainly focussed on the aggregation and spread of repeat domain of Tau in the cell culture models. Further studies are needed to elucidate the prion-like propagation property of full-length Tau and its aggregates in a more intense manner in vitro as well as in vivo conditions. Varied post-translational modifications can have discrete effects on aggregation propensity of Tau as well as its propagation. Here, we review the prion-like properties of Tau and hypothesize the role of glycation in prion-like properties of Tau. This post-translationally modified Tau might have an enhanced propagation property due to differential properties conferred by the modifications.     

Hyperglycemia in COVID-19 infection without diabetes mellitus: Association with inflammatory markers

BACKGROUND New onset hyperglycemia is common in patients with severe coronavirus disease 2019(COVID-19) infection. Cytokine storm due to COVID-19 infection is an essential etiology for new-onset hyperglycemia, but factors like direct severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)-induced pancreatic β-cell failure have also been postulated to play a role.AIM We plan to investigate further the mechanisms underlying SARS-CoV-2 infectioninduced hyperglycemia, particularly the rationale ...     

Evaluation of naphthalmustine, a nitrogen mustard derivative of naphthalimide as a rationally-designed anticancer agent

Naphthalmustine, 2-[2-[bis-(2-chloroethyl)amino]ethyl]-1H-benz[de]isoquinoline-1,3-dione (Compound 1) has been synthesized as a rationally designed new anticancer agent from N-(2-bromoethyl)naphthalimide. Its chemical alkylating activity exceeded that of nor-HN2 used as standard compound for comparison. Its antitumour efficacy was assessed in vivo in two murine ascites tumours namely Sarcoma-180 (S-180) and Ehrlich ascites carcinoma (EAC) by measuring the increase in median survival times (MST) of drug treated (T) over untreated control (C) mice. The clinical drug cyclophosphamide and the experimental compound mitonafide were used as positive controls for comparison. Compound 1 has displayed substantial and reproducible antitumoural activity in these tumours since very high remission times of treated animals were observed. Significant increase in the life span of mice bearing highly advanced tumour for 10 days before the drug challenge was also noted after its treatment. Its LD50 value was 200 mg/Kg by single i.p. injection. Its toxicity was also assessed in vivo in normal and in S-180 bearing mice by measuring drug-induced changes in hematological parameters, femoral bone marrow and splenic cellularity sequentially on days 9, 15 and 21 following drug treatment at the optimum dose of 12 mg/kg from day 1 to 7. The results indicated that the compound did not adversely affect hematopoiesis. Drug-induced hepatotoxicity and nephrotoxicity were also evaluated on those days but no such toxicities were detected. Naphthalmustine inhibits the synthesis of DNA and RNA in S-180 tumour cells. It was further screened in vitro in 4 different human tumour cell lines but no significant activity was observed in those lines.     

In vitro cytotoxic elemanolides from Vernonia lasiopus

Two new elemanolides, epivernodalol and lasiopulide, were isolated after chromatographic separation of the alcoholic extract of the dried aerial parts of the Vernonia lasiopus. These elemanolides are new C-10 epimers of the sesquiterpene lactones vernodalol and demethylacroylated vernodalol isolated from other species of Vernonia. Both elemanolides showed in vitro cytotoxicity against human cancer cell lines in culture. This is the first report of isolation and cytotoxic activity of the two elemanolides from V. lasiopus.     

Chemically standardized isolates from Cedrus deodara stem wood having anticancer activity

An isolate "CD lignan mixture" comprising lignans from stem wood of Cedrus deodara consisted of (-)-wikstromal (75 - 79%), (-)-matairesinol (9 - 13%) and benzylbutyrolactol (7 - 11%) and was studied for its in vitro cytotoxicity against human cancer cell lines. The in vivo anticancer activity of CD lignan mixture was studied using Ehrlich ascites carcinoma and colon carcinoma (CA-51) models in mice. Its effect was also studied on annexin V binding, intracellular caspases and DNA fragmentation to gain insight into the mode of action. In vitro cytotoxicity studies showed significant dose-dependent effects against several cancer cell lines from different tissues such as breast, cervix, neuroblastoma, colon, liver, and prostate at 10, 30 and 100 microg/mL. The IC (50) values varied from 16.4 ng/mL to 116.03 microg/mL depending on the cell line. Comparative data of IC (50) values of CD lignan mixture showed a synergistic effect in comparison to the individual molecules, i. e., (-)-matairesinol, (-)-wikstromol present in CD lignan mixture . CD lignan mixture had the most pronounced effect on CNS cell lines followed by colon. The tumor regression observed with Ehrlich ascites carcinoma and CA-51 was 53% and approximately 54%, respectively, when CD lignan mixture was given at 300 mg/kg, I. P. for nine days in the Ehrlich ascites carcinoma model and 400 mg/kg, I. P. for the same period in the CA-51 model. It was comparable with 5-fluorouracil at 22 mg/kg and 20 mg/kg, respectively. CD lignan mixture at 10, 30 and 100 microg/mL increased the percentage of annexin V positive HL-60 cells to 1.9 - 17.18% as compared to control (1.04%). In K562 cells CD lignan mixture at 10, 30 or 100 microg/mL and staurosporine (1 microM) showed 9.13%, 11.38%, 17.22% and 28.07% intracellular caspases activation, respectively. A distinct DNA laddering pattern was observed for treatment with the CD lignan mixture in HL-60, K562 (30 microg/mL and 100 microg/mL) and MOLT-4 cells (30 microg/mL) after 24 h incubation. DNA cell cycle analysis indicated that CD lignan mixture at 10, 30 and 100 microg/mL increased the content of hypodiploid (sub G(1) phase) cells when compared to control (2.55, 5.4 and 6.25% vs. 0.27%). The present study indicates that CD lignan mixture has cytotoxic potential against human cancer cell lines. It has the ability to induce tumor regression in vivo. It induces apoptosis as indicated by annexin V positive cells, induction of intracellular caspases, DNA fragmentation and DNA cell cycle analysis.     

A family with two consecutive nonsense mutations in BMPR1A causing juvenile polyposis

We describe a novel germline mutation of BMPR1A in a family with juvenile polyposis and colon cancer. This mutation consists of two consecutive substitutions (735-6 TG>AT) that cause two nonsense mutations (Y245X, G246X), inherited in an autosomal dominant fashion, on one parental chromosome. This mutation caused protein truncation, and represents a novel case of consecutive nonsense mutations in human disease.     

Epidermal stem cells have the potential to assist in healing damaged tissues

Homeostasis of continuously renewing tissues, such as the epidermis, is maintained by somatic undifferentiated, self-renewing stem cells, which are thought to persist throughout life. Through a series of labeling experiments, we previously showed that stem cells from mouse skin did not divide often, but they did divide at a steady rate in vivo. Using our recently redefined sorting method, we isolated epidermal stem and transit amplifying (TA) cells from mouse skin. When injected into a developing blastocyst or into damaged tissues, the stem cells, but not the TA cells, could participate in the formation of new tissues. We hypothesize that all tissues contain reserved undifferentiated stem cells that are primed to react if needed. These reserve stem cells could restore the tissue in which they reside or they could be called upon to help restore another tissue that was severely damage.     

Synthesis and evaluation of ethylnitrosoureas of substituted naphthalimides as anticancer compounds

Four new ethylnitrosourea derivatives of substituted naphthalimides 3a-d have been synthesized from the respective N-(2-ethylamino) naphthalimides. Their chemical alkylating activity compared with the clinical drug CCNU and an experimental compound Mitonafide indicated that they possess lower alkylating activity than CCNU and comparable activity with the latter. Their anti-tumor efficacies were assessed in vivo in two murine ascites tumors namely Sarcoma-180 (S-180) and Ehrlich ascites carcinoma (EAC) by measuring the increase in median survival times (MST) of drug treated (T) over untreated control (C) mice. CCNU and Mitonafide were used as positive controls for comparison. The representative compound 3a has displayed marginal anti-tumoral activity in these tumors. Three compounds were further screened in vitro in 4 different human tumor cell lines but no significant activity was observed in those lines. These compounds moderately inhibit the synthesis of DNA and RNA in S-180 tumor cells.