Seasonal and Temporal Variation in Release of Antibiotics in Hospital Wastewater: Estimation Using Continuous and Grab Sampling

The presence of antibiotics in the environment and their subsequent impact on resistance development has raised concerns globally. Hospitals are a major source of antibiotics released into the environment. To reduce these residues, research to improve knowledge of the dynamics of antibiotic release from hospitals is essential. Therefore, we undertook a study to estimate seasonal and temporal variation in antibiotic release from two hospitals in India over a period of two years. For this, 6 sampling sessions of 24 hours each were conducted in the three prominent seasons of India, at all wastewater outlets of the two hospitals, using continuous and grab sampling methods. An in-house wastewater sampler was designed for continuous sampling. Eight antibiotics from four major antibiotic groups were selected for the study. To understand the temporal pattern of antibiotic release, each of the 24-hour sessions were divided in three sub-sampling sessions of 8 hours each. Solid phase extraction followed by liquid chromatography/tandem mass spectrometry (LC-MS/MS) was used to determine the antibiotic residues. Six of the eight antibiotics studied were detected in the wastewater samples. Both continuous and grab sampling methods indicated that the highest quantities of fluoroquinolones were released in winter followed by the rainy season and the summer. No temporal pattern in antibiotic release was detected. In general, in a common timeframe, continuous sampling showed less concentration of antibiotics in wastewater as compared to grab sampling. It is suggested that continuous sampling should be the method of choice as grab sampling gives erroneous results, it being indicative of the quantities of antibiotics present in wastewater only at the time of sampling. Based on our studies, calculations indicate that from hospitals in India, an estimated 89, 1 and 25 ng/L/day of fluroquinolones, metronidazole and sulfamethoxazole respectively, might be getting released into the environment per 100 hospital beds.     

Low‐Overpotential Electrocatalytic Water Splitting with Noble‐Metal‐Free Nanoparticles Supported in a sp3 N‐Rich Flexible COF

Covalent organic frameworks (COFs) are crystalline organic polymers with tunable structures. Here, a COF is prepared using building units with highly flexible tetrahedral sp³ nitrogens. This flexibility gives rise to structural changes which generate mesopores capable of confining very small (<2 nm sized) non‐noble‐metal‐based nanoparticles (NPs). This nanocomposite shows exceptional activity toward the oxygen‐evolution reaction from alkaline water with an overpotential of 258 mV at a current density of 10 mA cm^?2. The overpotential observed in the COF‐nanoparticle system is the best in class, and is close to the current record of ≈200 mV for any noble‐metal‐free electrocatalytic water splitting system—the Fe–Co–Ni metal‐oxide‐film system. Also, it possesses outstanding kinetics (Tafel slope of 38.9 mV dec^?1) for the reaction. The COF is able to stabilize such small‐sized NP in the absence of any capping agent because of the COF–Ni(OH)₂ interactions arising from the N‐rich backbone of the COF. Density‐functional‐theory modeling of the interaction between the hexagonal Ni(OH)₂ nanosheets and the COF shows that in the most favorable configuration the Ni(OH)₂ nanosheets are sandwiched between the sp³ nitrogens of the adjacent COF layers and this can be crucial to maximizing their synergistic interactions.     

Rosuvastatin Treatment Affects Both Basal and Glucose-Induced Insulin Secretion in INS-1 832/13 Cells

Rosuvastatin is a member of the statin family. Like the other statins it is prescribed to lower cholesterol levels and thereby reduce the risk of cardiovascular events. Rosuvastatin lowers the cholesterol levels by inhibiting the key enzyme 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMG-CoA reductase) in the cholesterol producing mevalonate pathway. It has been recognized that apart from their beneficial lipid lowering effects, statins also exhibit diabetogenic properties. The molecular mechanisms behind these remain unresolved. To investigate the effects of rosuvastatin on insulin secretion, we treated INS-1 832/13 cells with varying doses (20 nM to 20 μM) of rosuvastatin for 48 h. At concentrations of 2 μM and above basal insulin secretion was significantly increased. Using diazoxide we could determine that rosuvastatin did not increase basal insulin secretion by corrupting the K_ATP channels. Glucose-induced insulin secretion on the other hand seemed to be affected differently at different rosuvastatin concentrations. Rosuvastatin treatment (20 μM) for 24–48 h inhibited voltage-gated Ca²⁺ channels, which lead to reduced depolarization-induced exocytosis of insulin-containing granules. At lower concentrations of rosuvastatin (≤ 2 μM) the stimulus-secretion coupling pathway was intact downstream of the K_ATP channels as assessed by the patch clamp technique. However, a reduction in glucose-induced insulin secretion could be observed with rosuvastatin concentrations as low as 200 nM. The inhibitory effects of rosuvastatin on glucose-induced insulin secretion could be reversed with mevalonate, but not squalene, indicating that rosuvastatin affects insulin secretion through its effects on the mevalonate pathway, but not through the reduction of cholesterol biosynthesis. Taken together, these data suggest that rosuvastatin has the potential to increase basal insulin secretion and reduce glucose-induced insulin secretion. The latter is possibly an unavoidable side effect of rosuvastatin treatment as it occurs through the same mechanisms as the lipid-lowering effects of the drug.     

Orally Active and Selective Tubulin Inhibitors as Anti-Trypanosome Agents

Objectives

There is an urgent need to develop a safe, effective, orally active, and inexpensive therapy for African trypanosomiasis due to the drawbacks of current drugs. Selective tubulin inhibitors have the potential to be promising drug candidates for the treatment of this disease, which is based on the tubulin protein structural difference between mammalian and trypanosome cells. We propose to identify novel tubulin inhibitors from a compound library developed based on the lead compounds that selectively target trypanosomiasis.

Methods

We used Trypanosoma brucei brucei as the parasite model, and human normal kidney cells and mouse microphage cells as the host model. Growth rates of both trypanosomes and mammalian cells were determined as a means to screen compounds that selectively inhibit the proliferation of parasites. Furthermore, we examined the cell cycle profile of the parasite and compared tubulin polymerization dynamics before and after the treatment using identified compounds. Last, in vivo anti-parasite activities of these compounds were determined in T. brucei-infected mice.

Results

Three compounds were selected that are 100 fold more effective against the growth of T. brucei cells than mammalian cells. These compounds caused cell cycle progression defects in T. brucei cells. Western analyses indicated that these compounds decreased tubulin polymerization in T. brucei cells. The in vivo investigation revealed that these compounds, when admitted orally, inhibited T. brucei cell proliferation in mouse blood. However, they were not potent enough to clear up the infection completely.

Conclusions

These compounds are promising lead compounds as orally active agents for drug development of anti-trypanosome agents. A more detail structure activity relationship (SAR) was summarized that will be used to guide future lead optimization to improve the selectivity and potency of the current compounds.     

A rapid,ideal, and eco-friendlier protocol for quantifying proline

Proline, a stress marker, is routinely quantified by a protocol that essentially uses hazardous toluene. Negative impacts of toluene on human health prompted us to develop a reliable alternate protocol for proline quantification. Absorbance of the proline-ninhydrin condensation product formed by reaction of proline with ninhydrin at 100 °C in the reaction mixture was significantly higher than that recorded after its transfer to toluene, revealing that toluene lowers sensitivity of this assay. λ _max of the proline-ninhydrin complex in the reaction mixture and toluene were 508 and 513 nm, respectively. Ninhydrin in glacial acetic acid yielded higher quantity of the proline-ninhydrin condensation product compared to ninhydrin in mixture of glacial acetic acid and H₃PO₄, indicating negative impact of H₃PO₄ on proline quantification. Further, maximum yield of the proline-ninhydrin complex with ninhydrin in glacial acetic acid and ninhydrin in mixture of glacial acetic acid and H₃PO₄ was achieved within 30 and 60 min, respectively. This revealed that H₃PO₄ has negative impact on the reaction rate and quantity of the proline-ninhydrin complex formed. In brief, our proline quantification protocol involves reaction of a 1-ml proline sample with 2 ml of 1.25 % ninhydrin in glacial acetic acid at 100 °C for 30 min, followed by recording absorbance of the proline-ninhydrin condensation product in the reaction mixture itself at 508 nm. Amongst proline quantification protocols known till date, our protocol is the most simple, rapid, reliable, cost-effective, and eco-friendlier.