Release of doxycycline through cellulose acetate symmetric and asymmetric membranes produced from recycled agroindustrial residue: Sugarcane bagasse

Cellulose acetate is one of the components employed in drug controlled-release systems in the form of membranes. The aim of this study was to examine the controlled-release of doxycycline employing cellulose acetate symmetric and asymmetric membranes as matrices. The cellulose triacetate was produced from sugarcane bagasse through a homogeneous acetylation reaction, using acetic acid as the solvent, acetic anhydride as the acetylating agent and sulfuric acid as the catalyst. The viscosity average molecular weight of the cellulose acetate produced was 39,000 g mol⁻¹. The symmetric membranes were produced using a system solvent of dichloromethane/ethanol (9:1, v/v) and the asymmetric membranes were produced from the same solvent system and 10% of water. For the formulation of both, 5% of doxycycline was used. The membranes were characterized by thermal analysis (DSC and TGA) and scanning electron microscopy SEM. The release of doxycycline through cellulose triacetate matrices was examined using spectrophotometric analysis in the ultraviolet-visible region, at 275 nm. The results revealed that asymmetric membranes release 80% of the drug in 100 min, while symmetric membranes release 14% of the drug during the same time interval.     

Effects of dredging operations on sediment quality: contaminant mobilization in dredged sediments from the Port of Santos, SP, Brazil

Background, aim, and scope  

Contaminated sediments are a worldwide problem, and mobilization of contaminants is one of the most critical issues in environmental risk assessment insofar as dredging projects are concerned. The investigation of how toxic compounds are mobilized during dredging operations in the channel of the Port of Santos, Brazil, was conducted in an attempt to assess changes in the bioavailability and toxicity of these contaminants.     

Germination and seedling growth of <Emphasis Type="Italic">Dimorphandra jorgei</Emphasis> MF Silva and <Emphasis Type="Italic">Swartzia macrostachya</Emphasis> Benth. var. <Emphasis Type="Italic">riedelii</Emphasis> Cowan

Dimorphandra jorgei MF Silva (Caesalpinaceae) and Swartzia macrostachya Benth. var. riedelii Cowan (Fabaceae) are tree species from the southern Bahian Atlantic Forest, identified for the restoration of degraded areas. The objective of this research is to study their seed germination and seedling growth to develop simple methods for seedling production in small scale nurseries. Because the species have distinct dormancy and germination characteristics, the seeds were submitted to different treatments. D. jorgei seeds were immersed in hot water, scarified and stored for 12 weeks in the laboratory environment (25°C). S. macrostachya seeds were submitted to different combinations of drying and storage in the laboratory environment or refrigerator (4°C). Seedlings were submitted to two light treatments for 3 months: partial shade (52% of full sun) and full shade (12% of full sun). In D. jorgei, the highest germination occurred for scarified seeds (87%) and for seeds stored for 12 weeks and then scarified (69%). In S. macrostachya the undried control seeds had the highest germination, followed by that of the refrigeration storage treatment, without predrying (99% and 97%, respectively). The average values for the growth parameters were greater in full shade for D. jorgei, while S. macrostachya seedlings showed greater growth rates in partial shade. Two months growth is recommended before D. jorgei seedlings are of the sufficient size and leaf number for field planting. On the other hand, a period of 4 months is recommended for S. macrostachya, due to its relatively slow growth.     

Natural Stable Isotopes for Determination of Gastrointestinal Transit Time in Fish

This study evaluated the application of stable isotopes of carbon as an alternative and more accurate method to determine gastrointestinal transit time (GTT) in fish by comparing it to the inert marker method. The stable isotope method detects alterations of the normal carbon flow in a biological system by analyzing naturally occurring isotopes of carbon, contrary to studies based on conventional techniques that apply external markers to the diet to determine GTT through visual observation of the color change in feces. Therefore, 320 pacu, Piaractus mesopotamicus juveniles were reared in 32 tanks under two different temperatures (25 and 29 C). The pacu juveniles received two different diets, one based on ingredients derived from C₃ photosynthetic cycle plants and the other based on C₄ plant ingredients, both containing titanium oxide (TiO₂) as a marker. After 40 d, the isotopic signature of the diets was changed, and the marker was replaced by chromic oxide (Cr₂O₃). In the isotopic technique, the feces were analyzed to determine the exchange in the isotopic ratio of carbon δ¹³C. Both methods found that GTT was faster (nearly 6 h) in fish at 29 C when using the C₄/C₃ feeding strategy and slower in fish at 25 C using the C₃/C₄ strategy (15 h by inert marker and 18 h by the isotopic method). In conclusion, GTT determination in pacu juveniles using the stable isotope technique exhibits the same accuracy obtained with the inert marker method at temperatures suitable (nearly 29 C) for the metabolism of these animals.     

A new Delta7,22 sterol from the bulbs of Autonoë madeirensis

The spectral data of a new Δ^7,22 sterol, 24S-ethyl-5α-cholesta-7,22E-dien-3α-ol β-galactopyranoside, isolated from the bulbs of Autonoë madeirensis, are reported.     

Influences of Sex and Age on the Hematological Profile of the Jundiá (Silver Catfish) Rhamdia quelen

In this study, sex and age influenced the hematological profiles of Jundiá (Silver Catfish) Rhamdia quelen. Females showed lower levels of hemoglobin, young fish increased lymphocyte counts, and older fish increased hematocrit values. These results indicate that, depending on age and sex, the fish have disparate hematological profiles. For this reason, it is important to consider the sex and age of an R. quelen when examining the impact of environmental and management factors on this species in terms of their hematological profiles.

Received May 24, 2015; accepted March 24, 2016 Published online August 2, 2016     

LED-Induced Chlorophyll Fluorescence Spectral Analysis for the Early Detection and Monitoring of Cadmium Toxicity in Maize Plants

Chlorophyll fluorescence spectral analysis permits detection, monitoring, and evaluation of abiotic stresses upon healthy plants using illumination of a light source in the UV?CVIS spectral range. This technique indirectly assesses the amount of physiological stress caused by photosynthetic damage, specifically damage to photosystem II, in plants. The objective of this study was to detect the toxicity of cadmium in maize plants via spectral analysis of chlorophyll fluorescence. The analysis is noninvasive and nondestructive and is used to follow the temporal evolution of changes in the chlorophyll content and physiological state of Zea mays L. seedlings under cadmium stress. Conventional techniques were also used to evaluate the dry matter production and Cd accumulation in plant leaves. Plants exhibited a notable reduction in dry matter production and chlorophyll levels with the administration of increasing doses of Cd in the nutrient solution. The fluorescence analysis was sensitive to changes caused by Cd in maize plants, detecting damage caused by different treatments before visual symptoms were observed. This technique has a practical application and produces rapid results that can be used in the evaluation of Cd-induced stress in plants and the detection of areas contaminated by this element.