Examination of aqueous oxidized cellulose dispersions as a potential drug carrier. I. Preparation and characterization of oxidized cellulose-phenylpropanolamine complexes

Partially neutralized aqueous dispersions of oxidized cellulose (OC) (COOH content 24.2%; degree of neutralization [DN] 0.22-0.44; solid content 14.4% wt/wt), a biocompatible biodegradable polymer, were prepared and their use to entrap an amine drug was demonstrated. Phenylpropanolamine hydrochloride (PPA.HCl) was used as a model drug. OCA-PPA complexes were prepared by adding the drug solution to the OC dispersion. Light microscopy, powder x-ray diffractometry (PXRD), and Fourier-transform infrared (FT-IR) spectroscopy were used to characterize hydrated and dried OC and the OC-PPA complexes. Drug loading and drug-loading efficiency were calculated from high-performance liquid chromatography. Light microscopy revealed the partially neutralized OC to exist as swollen fibers in the dispersion. The degree of swelling increased with increasing DN of the OC. All dispersions, irrespective of DN, showed a pseudo-plastic flow. The drug loading (12.6%-26.7%) and drug-loading efficiency (30%-48%) increased linearly with increasing DN and drug concentration. The PXRD of the OC-PPA complexes showed no diffraction peaks due to PPA, suggesting that the drug exists in the amorphous state. The FT-IR spectra of the complexes revealed the presence of an ionic linkage between OC and PPA. In conclusion, the results show that the aqueous OC dispersions can be used to molecularly entrap amine drugs to produce an OC-drug complex linked via an ionic linkage.     

Examination of aqueous oxidized cellulose dispersions as a potential drug carrier: II. In vitro and in vivo evaluation of phenylpropanolamine release from microparticles and pellets

The purpose of this research is to investigate the release of phenylpropanolamine from oxidized cellulose-phenylpropanolamine (OC-PPA) complexes prepared using aqueous OC dispersions (degree of neutralization, DN, 0–0.44) and phenylpropanolamine-hydrochloride (PPA.HC1) (concentration, 0.5 M or 1.4 M) in vitro and in vivo. The results showed a faster drug release from the OC-PPA complex made using the OC dispersion with a DN value of 0.22 than from those prepared using dispersions with DN values of 0.29 to 0.44. No significant difference existed between the release profiles of OC-PPA microparticles made using OC dispersions with DN values of 0.29 to 0.44 OC-PPA complexes that contained smaller size particles or higher drug levels, or that were processed by freeze drying released PPA faster. Compared with microparticles, the pellets of OC-PPA complexes released PPA more slowly initially. An increase in pH or ionic strength of the dissolution medium increased the release of PPA, which is attributable to increased polymer hydration and solubilization at higher pH and ionic strength conditions. The OC-PPA pellets implanted subcutaneously in rats released 100% of their PPA in 9 to 12 hours. Agood correlation was found between the in vivo and in vitro release data. Tissue pathology results showed no significant inflammatory tissue reactions. In conclusion, the partially ionized aqueous OC dispersions have the potential to be used as an implantable biodegradable carrier for amine drugs.     

Effect of light intensity on the phase and period response curves in the nocturnal field mouse Mus booduga

The effect of light intensity on the phase response curve (PRC) and the period response curve (τRC) of the nocturnal field mouse Mus booduga was studied. PRCs and τRCs were constructed by exposing animals free-running in constant darkness (DD), to fluorescent light pulses (LPs) of 100 lux and 1000 lux intensities for 15min duration. The waveform of the PRCs and τRCs evoked by high light intensity (1000 lux) stimuli was significantly different compared to those constructed using low light intensity (100 lux). Moreover, a weak but significant correlation was observed between phase shifts and period changes when light stimuli of 1000 lux intensity were used; however, the phase shifts and period changes in the 100 lux PRC and τRC were not correlated. This suggests that the intensity of light stimuli affects both phase and period responses in the locomotor activity rhythm of the nocturnal field mouse M. booduga. These results indicate that complex mechanisms are involved in entrainment of circadian clocks, even in nocturnal rodents, in which PRC, τRC, and dose responses play a significant role.     

Histamine mediates the pro-inflammatory effect of latex of Calotropis procera in rats

INTRODUCTiON: Calotropis procera is known to produce contact dermatitis and the latex of this plant produces intense inflammation when injected locally. However, the precise mode of its pro-inflammatory effect is not known. In present study we have pharmacologically characterized the inflammation induced by latex of C. procera in a rat paw edema model and determined the role of histamine in latex-induced inflammation. METHODS: Inflammation was induced in the hind paw of rats by injecting different doses of dried latex (DL) of C. procera. The inhibitory effect of phenylbutazone, dexamethasone, celecoxib, cyproheptadine, chlorpheniramine and compound 48/80 on edema volume was evaluated and compared with that against carrageenan. The histamine content of DL was measured fluorometrically. RESULTS: DL produced dose-dependent inflammation of the rat paw. Cyproheptadine and chlorpheniramine effectively inhibited DL-induced inflammation (90%; p < 0.01), while anti-inflammatory drugs phenylbutazone, dexamethasone and celecoxib were more effective against carrageenan-induced inflammation. Depletion of mast cell histamine by compound 48/80 produced a significant decrease in DL-induced inflammation as compared with carrageenan (500% versus 25%). DL was also found to contain about 6 microg/g of histamine. CONCLUSIONS: Thus, our study shows that the biogenic amines play a significant role in C. procera latex-induced inflammation and antihistaminic drugs could be effectively used to inhibit inflammatory response elicited by exposure to latex.     

Quantitative structure-activity relationship study on sulfanilamide schiff's bases: carbonic anhydrase (CA) inhibitors

The paper deals with quantitative structure–activity studies on a group of sulfanilamide Schiff's base inhibitors of carbonic anhydrase (CA) using distance-based topological indices. The regression analysis of the data has shown that the activities of the compounds used in inhibiting Carbonic AnhydraseII (CAII) activity can be modeled excellently in multi-parametric model in that some indicator parameters are also involved. The results are discussed critically.     

Immunomodulation by peptide analogs of retroviral envelope protein

The mechanism by which retroviral proteins exert their immunosuppressive influence has remained enigmatic. Early studies have demonstrated that retroviral infection suppresses cellular and humoral immune responses. A hydrophilic 26 amino acid region of the otherwise hydrophobic transmembrane envelope protein of murine and feline leukemia viruses, p15E, is conserved among the transmembrane envelope proteins of numerous animal retroviruses (e.g. murine, feline, bovine and simian) as well as in human T-cell leukemia virus, and to a lesser extent, in human immunodeficiency virus (HIV). We evaluated the immunomodulatory properties of various synthetic retroviral envelope peptides synthesized as overlapping fragments to this conserved sequence. We report that two small peptides inhibit human mixed lymphocyte reaction (MLR), interleukin-2 (IL-2) and tumor necrosis factor (TNF-alpha) production. These peptides did not affect human natural killer (NK) cell cytotoxicity in vitro, and nitric oxide (NO) production in mouse macrophage cells, RAW264.7. Our observations suggests immunomodulatory potential of two retroviral peptide analogs.     

Luminescence studies of a Li2Ca1−xSiO4:xSm3+ phosphor for the generation of white light under NUV-excited phosphor converting LEDs

In this paper, we present new aspects of Sm³⁺-doped pure Li₂CaSiO₄ as a suitable candidate for white light emitting diode (WLED) applications. The samples were mainly prepared using a conventional modified solid-state synthesis technique. The structural studies were done using X-ray diffraction and Rietveld refinement. Instruments such as a scanning electron microscope (SEM) were used to obtain information about the morphology of the as-prepared samples. Photoluminescence (PL) analysis of phosphor samples for variable concentrations of doping ions with variable excitations were presented. When doped with Sm³⁺ in host Li₂CaSiO₄ it emitted intense blue, green and red emissions and a more intense red emission peak (605 nm) under 408 nm excitation (near-UV–blue). Our study shows that the as-prepared phosphor may be useful for optical devices and mainly for WLEDs. The corresponding transitions of doping ions and concentration quenching effect were studied in detail. The 1931 Commission Internationale de l'Eclairage (x, y) chromaticity coordinates showed the distribution of spectral regions calculated from PL emission spectra and this was found (0.63, 0.36) in the red region, so the phosphor may be useful for near-UV–blue excited WLED applications.     

Biofilms as a microbial hazard in the food industry: A scoping review

Biofilms pose a serious public health hazard with a significant economic impact on the food industry. The present scoping review is designed to analyse the literature published during 2001–2020 on biofilm formation of microbes, their detection methods, and association with antimicrobial resistance (if any). The peer-reviewed articles retrieved from 04 electronic databases were assessed using PRISMA-ScR guidelines. From the 978 preliminary search results, a total of 88 publications were included in the study. On analysis, the commonly isolated pathogens were Listeria monocytogenes, Staphylococcus aureus, Salmonella spp., Escherichia coli, Bacillus spp., Vibrio spp., Campylobacter jejuni and Clostridium perfringens. The biofilm-forming ability of microbes was found to be influenced by various factors such as attachment surfaces, temperature, presence of other species, nutrient availability etc. A total of 18 studies characterized the biofilm-forming genes, particularly for S. aureus, Salmonella spp., and E. coli. In most studies, polystyrene plate and/or stainless-steel coupons were used for biofilm formation, and the detection was carried out by crystal violet assays and/or by plate counting method. The strain-specific significant differences in biofilm formation were observed in many studies, and few studies carried out analysis of multi-species biofilms. The association between biofilm formation and antimicrobial resistance was not clearly defined. Further, viable but non-culturable form of the foodborne pathogens is posing an unseen (by conventional cultivation techniques) but potent threat to the food safety. The present review recommends the need for carrying out systematic surveys and risk analysis of biofilms in food chain to highlight the evidence-based public health concerns, especially in regions where microbiological food hazards are quite prevalent.