Cell growth rate dictates the onset of glass to fluid-like transition and long time super-diffusion in an evolving cell colony

Collective migration dominates many phenomena, from cell movement in living systems to abiotic self-propelling particles. Focusing on the early stages of tumor evolution, we enunciate the principles involved in cell dynamics and highlight their implications in understanding similar behavior in seemingly unrelated soft glassy materials and possibly chemokine-induced migration of CD8$^{+}$ T cells. We performed simulations of tumor invasion using a minimal three dimensional model, accounting for cell elasticity and adhesive cell-cell interactions as well as cell birth and death to establish that cell growth rate-dependent tumor expansion results in the emergence of distinct topological niches. Cells at the periphery move with higher velocity perpendicular to the tumor boundary, while motion of interior cells is slower and isotropic. The mean square displacement, $\Delta(t)$, of cells exhibits glassy behavior at times comparable to the cell cycle time, while exhibiting super-diffusive behavior, $\Delta (t) \approx t^{\alpha}$ ($\alpha > 1$), at longer times. We derive the value of $\alpha \approx 1.33$ using a field theoretic approach based on stochastic quantization. In the process we establish the universality of super-diffusion in a class of seemingly unrelated non-equilibrium systems. Super diffusion at long times arises only if there is an imbalance between cell birth and death rates. Our findings for the collective migration, which also suggests that tumor evolution occurs in a polarized manner, are in quantitative agreement with {\it in vitro} experiments. Although set in the context of tumor invasion the findings should also hold in describing collective motion in growing cells and in active systems where creation and annihilation of particles play a role.Comment: 56 pages, 19 figure

A comparative study of early and delayed cord clamping in term deliveries

Background: Timing of clamping of the umbilical cord has always been a debatable issue. Early cord clamping (ECC) is defined as clamping of the cord within 30 seconds of delivery of the baby and delayed cord clamping (DCC) is defined as clamping of the cord between 30 to 120 seconds of delivery. Delayed cord clamping, despite some limitations, is said to be beneficial to the neonate.  A comparative study between ECC and DCC was carried out on a select group of term pregnant women without any high-risk factor and delivering at term. Aim of the study was to compare the effects of early versus delayed cord clamping on neonates and mothers. The focus was on the neonatal haemoglobin levels and adverse effects, if any on neonates and mothers in the two groups.Methods: 100 women satisfying the inclusion/exclusion criteria were recruited for the study. They were randomly divided into two groups of 50 each. Group A underwent early cord clamping and Group B delayed cord clamping. Mothers were observed for 1 hour post-delivery for any evidence of post-partum haemorrhage. Neonates were observed for any sign of tachypnea and blood sample was sent after 72 hours of delivery for analyzing Hb, hematocrit and bilirubin of the neonate.Results: The results revealed that neonates with DCC had a higher mean Hb level of 15.02 vis-à-vis the ECC group Hb of 11.69G/dl and the difference was statistically significant. Similarly mean hematocrit of DCC group was 48.67 while the ECC group mean was 42.36, the difference again was statistically significant. There was no significant side effects or complications in both mother and newborn babies.Conclusions: It was concluded that delayed cord clamping should be practiced in otherwise non high-risk deliveries

Cyanobacterial Alkanes Modulate Photosynthetic Cyclic Electron Flow to Assist Growth under Cold Stress

All cyanobacterial membranes contain diesel-range C15-C19 hydrocarbons at concentrations similar to chlorophyll. Recently, two universal but mutually exclusive hydrocarbon production pathways in cyanobacteria were discovered. We engineered a mutant of Synechocystis sp. PCC 6803 that produces no alkanes, which grew poorly at low temperatures. We analyzed this defect by assessing the redox kinetics of PSI. The mutant exhibited enhanced cyclic electron flow (CEF), especially at low temperature. CEF raises the ATP:NADPH ratio from photosynthesis and balances reductant requirements of biosynthesis with maintaining the redox poise of the electron transport chain. We conducted in silico flux balance analysis and showed that growth rate reaches a distinct maximum for an intermediate value of CEF equivalent to recycling 1 electron in 4 from PSI to the plastoquinone pool. Based on this analysis, we conclude that the lack of membrane alkanes causes higher CEF, perhaps for maintenance of redox poise. In turn, increased CEF reduces growth by forcing the cell to use less energy-efficient pathways, lowering the quantum efficiency of photosynthesis. This study highlights the unique and universal role of medium-chain hydrocarbons in cyanobacterial thylakoid membranes: they regulate redox balance and reductant partitioning in these oxygenic photosynthetic cells under stress

Cyanobacterial Alkanes Modulate Photosynthetic Cyclic Electron Flow to Assist Growth under Cold Stress

All cyanobacterial membranes contain diesel-range C15-C19 hydrocarbons at concentrations similar to chlorophyll. Recently, two universal but mutually exclusive hydrocarbon production pathways in cyanobacteria were discovered. We engineered a mutant of Synechocystis sp. PCC 6803 that produces no alkanes, which grew poorly at low temperatures. We analyzed this defect by assessing the redox kinetics of PSI. The mutant exhibited enhanced cyclic electron flow (CEF), especially at low temperature. CEF raises the ATP:NADPH ratio from photosynthesis and balances reductant requirements of biosynthesis with maintaining the redox poise of the electron transport chain. We conducted in silico flux balance analysis and showed that growth rate reaches a distinct maximum for an intermediate value of CEF equivalent to recycling 1 electron in 4 from PSI to the plastoquinone pool. Based on this analysis, we conclude that the lack of membrane alkanes causes higher CEF, perhaps for maintenance of redox poise. In turn, increased CEF reduces growth by forcing the cell to use less energy-efficient pathways, lowering the quantum efficiency of photosynthesis. This study highlights the unique and universal role of medium-chain hydrocarbons in cyanobacterial thylakoid membranes: they regulate redox balance and reductant partitioning in these oxygenic photosynthetic cells under stress

A study of comparison of efficacy and side effects of intravenous paracetamol and intravenous diclofenac as a postoperative analgesic

BBackground: A postoperative patient suffers from pain the best relief of which is a clinician’s duty. Till date very few studies have been conducted for comparison of paracetamol and diclofenac as analgesics. As a result a comparative study between Paracetamol and Diclofenac was carried out. The aim of the study was to compare the efficacy and side effects of intravenous Paracetamol and intravenous Diclofenac in patients undergoing major abdominal open surgeries in obstetrics and gynaecology. The study was conducted to assess the postoperative visual analogue pain scores (VAS) and total analgesic requirement in the first 24 hours and also to study the total requirement of additional analgesics despite administration of either Paracetamol or Diclofenac in postoperative period.Methods: 100 patients satisfying the inclusion/exclusion criteria were recruited for the study. They were divided into two groups of 50 each. Group A was given IV Paracetamol 6 hourly for 48 hours starting 2 hours after surgery. Group B was given IV Diclofenac 8 hourly for 48 hours starting 2 hours after surgery. Patients were assessed for pain relief by visual analogue scale (VAS) of zero to ten after 6 hours, 12 hours, 24 hours and 48 hours of surgery by asking the patient to point the position on the 100 mm scale.Results: The results revealed that when we compared the VAS scores between the 2 Groups at different time intervals, it showed that at 24 hours and 48 hours VAS score in the Diclofenac Group was significantly less than the Paracetamol Group. The main side effects were nausea and vomiting in both the groups. There was more nausea and vomiting in Diclofenac group compared to Paracetamol group.Conclusions: It was concluded that at 24 hour and 48 hour pain reduction was more in the Diclofenac group as compared to Paracetamol group, but the side effects were more in the Diclofenac group compared to Paracetamol group