Nitric Oxide Synthase Activity and Angiogenesis Measured by Expression of CD34 in Burns Treated With Chitosan Films .

UNLABELLED:  Nitric oxide (NO) signaling appears to play a vital role in wound healing associated to improve collagen and angiogenesis. A burn wound model was used to evaluate the effects of a chitosan films on histopathological features, nitric oxide synthase (NOS) activity, and quantification of neoformed capillaries assessed with CD34. METHODS: Bilateral burns (n = 16) were made on adult Sprague-Dawley rats. The lesions on the right side of the rats were treated with chitosan films, and the lesions on the left side of the same rats were treated with gauze with NaCl 0.9% as a control. RESULTS: Histological analysis revealed accelerated burn wound healing supported by significant differences in acute inflammation, collagen, and granulation tissue formation in chitosan-treated burns. Additionally, chitosan-treated burns were associated with higher CD34 immunoreactivity antibody supported by significant differences. This analysis of NOS activity was statistically significant on treated burns in the second treatment week. NOS results are associated with the highest collagen deposition, granulation tissue formation, and new capillary formation. CONCLUSION: The use of chitosan on burns promoted re-epithelialization by means of angiogenic and NO release associated with higher cell infiltration into the wound bed during the proliferative phase.

Direct and indirect nigrofugal projections to the nucleus reticularis pontis caudalis mediate in the motor execution of the acoustic startle reflex.

The acoustic startle reflex (ASR) is a short and intense defensive reaction in response to a loud and unexpected acoustic stimulus. In the rat, a primary startle pathway encompasses three serially connected central structures: the cochlear root neurons, the giant neurons of the nucleus reticularis pontis caudalis (PnC), and the spinal motoneurons. As a sensorimotor interface, the PnC has a central role in the ASR circuitry, especially the integration of different sensory stimuli and brain states into initiation of motor responses. Since the basal ganglia circuits control movement and action selection, we hypothesize that their output via the substantia nigra (SN) may interplay with the ASR primary circuit by providing inputs to PnC. Moreover, the pedunculopontine tegmental nucleus (PPTg) has been proposed as a functional and neural extension of the SN, so it is another goal of this study to describe possible anatomical connections from the PPTg to PnC. Here, we made 6-OHDA neurotoxic lesions of the SN pars compacta (SNc) and submitted the rats to a custom-built ASR measurement session to assess amplitude and latency of motor responses. We found that following lesion of the SNc, ASR amplitude decreased and latency increased compared to those values from the sham-surgery and control groups. The number of dopamine neurons remaining in the SNc after lesion was also estimated using a stereological approach, and it correlated with our behavioral results. Moreover, we employed neural tract-tracing techniques to highlight direct projections from the SN to PnC, and indirect projections through the PPTg. Finally, we also measured levels of excitatory amino acid neurotransmitters in the PnC following lesion of the SN, and found that they change following an ipsi/contralateral pattern. Taken together, our results identify nigrofugal efferents onto the primary ASR circuit that may modulate motor responses.

Capreomycin oleate microparticles for intramuscular administration: Preparation, in vitro release and preliminary in vivo evaluation.

Capreomycin sulfate (CS) is a second-line drug used for the treatment of multidrug-resistant tuberculosis (MDR-TB). The adverse effects profile and uncomfortable administration scheme of CS has led to the development of formulations based on liposomes and polymeric microparticles. However, as CS is a water-soluble peptide that does not encapsulate properly into hydrophobic particulate matrices, it was necessary to reduce its aqueous solubility by forming the pharmacologically active capreomycin oleate (CO) ion pair. The aim of this research was to develop a new formulation of CO for intramuscular injection, based on biodegradable microparticles that encapsulate CO in order to provide a controlled release of the drug with reduced local and systemic adverse effects. The CO-loaded microparticles prepared by spray drying or solvent emulsion-evaporation were characterized in their morphology, encapsulation efficiency, in vitro/in vivo kinetics and tissue tolerance. Through scanning electron microscopy it was confirmed that the microparticles were monodisperse and spherical, with an optimal size for intramuscular administration. The interaction between CO and the components of the microparticle matrix was confirmed on both formulations by X-ray powder diffraction and differential scanning calorimetry analyses. The encapsulation efficiencies for the spray-dried and emulsion-evaporation microparticles were 92% and 56%, respectively. The in vitro kinetics performed on both formulations demonstrated a controlled and continuous release of CO from the microparticles, which was successfully reproduced on an in vivo rodent model. The results of the histological analysis demonstrated that none of the formulations produced significant tissue damage on the site of injection. Therefore, the results suggest that injectable CO microparticles obtained by spray drying and solvent emulsion-evaporation could represent an interesting therapeutic alternative for the treatment of MDR-TB.

Neurochemical changes of the extracellular concentrations of glutamate and aspartate in the nucleus accumbens of rats after chronic administration of morphine.

The effects of discontinuing a chronic morphine treatment on the concentrations of glutamate and aspartate were analyzed in the nucleus accumbens of unrestrained unanesthetized rats. The administration of naloxone or the cessation of morphine administration resulted in increased concentrations of glutamate and aspartate in this central nervous system area. These increased amino acid concentrations were observed a few minutes after naloxone administration and persisted in the controls 48 h after the last dose of the opiate. Morphine withdrawal was also studied in rats not injected with naloxone. In these latter animals, increased concentrations of glutamate and aspartate persisted in controls 96 h after the last dose of the opiate. Single doses of morphine, acamprosate or riluzole administered to rats previously withdrawn from chronic morphine treatment restored the amino acid concentrations to normal levels. These results suggest that the maintenance of increased levels of amino acids could be the expression of new adjustments in central nervous system neurotransmission after discontinuation of the chronic morphine treatment.

Acamprosate decreases the induction of tolerance and physical dependence in morphine-treated mice.

The effects of acamprosate, a drug thought to interact with N-methyl-D-aspartate (NMDA) receptors in the central nervous system (CNS), were examined on the antinociceptive action of morphine, induction of tolerance to and physical dependence on morphine, and expression of the abstinence syndrome to the opiate in mice. For the induction of tolerance and dependence, morphine (300 mg/kg) was administered by means of a slow-release preparation. Single doses of acamprosate (50, 100, 200, or 400 mg/kg) administered 30 min before a test dose of morphine did not change the antinociceptive effects of morphine in drug-naive mice. The drug was also administered in repeated doses (50, 100, 200, or 400 mg/kg, 30 min before and 12 and 24 h after the priming dose of morphine) in order to evaluate its effects on the induction of tolerance; all doses assayed, except the 400 mg/kg, did not affect the intensity of tolerance. The acute administration of acamprosate (50, 100, 200, or 400 mg/kg, injected 30 min before naloxone to morphine-pretreated mice) did not affect the intensity of the abstinence behavior. However, the repeated administration of 100 mg/kg of acamprosate (30 min before and 12 and 24 h after the priming dose of morphine) decreased the intensity of physical dependence. The results of these studies suggest that acamprosate may have modulatory effects on glutamatergic neurotransmission participating in the adaptive mechanisms induced by chronic morphine treatment.

Technique validation by liquid chromatography for the determination of acyclovir in plasma.

In this research project, a high-performance liquid chromatography (HPLC) method was developed for the determination of acyclovir (ACV) in plasma. The plasma samples, recharged with acyclovir and in presence of 5'-N-methylcarboxyamidoadenosine (MECA) as an internal standard, were purified using a solid-phase extraction technique with Waters Oasis HLB columns. The separation of the components from the extract was carried out in a LiChrospher 100 RP-18 column for further ultraviolet detection at a wavelength range of 250-260 nm. The mobile phase composition was 18% acetonitrile, sodium dodecylsulphate 5 mM and phosphate buffer at pH 2.6 with an analysis time of 13 min per sample. The average retention time for acyclovir was of 5.0 min and for the internal standard 11.2 min. The calibration curve was linear ranging between 0.05 and 1.80 microg/ml. The detection limit was 0.006 microg/ml with a quantification limit of 0.020 microg/ml. The ACV recuperation percentage for 250 microl of plasma was between 94.7 and 109.7% with a coefficient of variation not higher than 5.2%. This method was developed and validated for use in bioavailability and bioequivalence studies.

Preliminary pharmacokinetic study of different preparations of acyclovir with beta-cyclodextrin.

Acyclovir has absorption problems, because of its low solubility and/or its saturable absorption mechanism, that take place in the small intestine in a passive, variable, and incomplete manner. The oral bioavailability of acyclovir is thereby affected and reaches only 15-30%. The purpose of this study was to investigate the possibility of increasing the oral availability of acyclovir by forming inclusion complexes of acyclovir with beta-cyclodextrin. Acyclovir, its complex (1:1) with beta-cyclodextrin (acyclovir-beta-cyclodextrin complex), and a 50:50 mixture of acyclovir and the inclusion complex (acyclovir/complex mixture) as an aqueous suspension were administered intraintestinally to male Sprague-Dawley rats in doses equivalent to an acyclovir dose of 75 mg/kg. Sequential samples of plasma were taken by microdialysis. The samples were analyzed by high-performance liquid chromatography with ultraviolet detection. Plasma concentration versus time curves show that the complex and the mixture of acyclovir/complex have a higher bioavailability and a pharmacokinetic profile than that of the drug itself.