VPA/PLGA microfibers produced by coaxial electrospinning for the treatment of central nervous system injury.

The central nervous system shows limited regenerative capacity after injury. Spinal cord injury (SCI) is a devastating traumatic injury resulting in loss of sensory, motor, and autonomic function distal from the level of injury. An appropriate combination of biomaterials and bioactive substances is currently thought to be a promising approach to treat this condition. Systemic administration of valproic acid (VPA) has been previously shown to promote functional recovery in animal models of SCI. In this study, VPA was encapsulated in poly(lactic-co-glycolic acid) (PLGA) microfibers by the coaxial electrospinning technique. Fibers showed continuous and cylindrical morphology, randomly oriented fibers, and compatible morphological and mechanical characteristics for application in SCI. Drug-release analysis indicated a rapid release of VPA during the first day of the in vitro test. The coaxial fibers containing VPA supported adhesion, viability, and proliferation of PC12 cells. In addition, the VPA/PLGA microfibers induced the reduction of PC12 cell viability, as has already been described in the literature. The biomaterials were implanted in rats after SCI. The groups that received the implants did not show increased functional recovery or tissue regeneration compared to the control. These results indicated the cytocompatibility of the VPA/PLGA core-shell microfibers and that it may be a promising approach to treat SCI when combined with other strategies.

VPA/PLGA microfibers produced by coaxial electrospinning for the treatment of central nervous system injury

The central nervous system shows limited regenerative capacity after injury. Spinal cord injury (SCI) is a devastating traumatic injury resulting in loss of sensory, motor, and autonomic function distal from the level of injury. An appropriate combination of biomaterials and bioactive substances is currently thought to be a promising approach to treat this condition. Systemic administration of valproic acid (VPA) has been previously shown to promote functional recovery in animal models of SCI. In this study, VPA was encapsulated in poly(lactic-co-glycolic acid) (PLGA) microfibers by the coaxial electrospinning technique. Fibers showed continuous and cylindrical morphology, randomly oriented fibers, and compatible morphological and mechanical characteristics for application in SCI. Drug-release analysis indicated a rapid release of VPA during the first day of the in vitro test. The coaxial fibers containing VPA supported adhesion, viability, and proliferation of PC12 cells. In addition, the VPA/PLGA microfibers induced the reduction of PC12 cell viability, as has already been described in the literature. The biomaterials were implanted in rats after SCI. The groups that received the implants did not show increased functional recovery or tissue regeneration compared to the control. These results indicated the cytocompatibility of the VPA/PLGA core-shell microfibers and that it may be a promising approach to treat SCI when combined with other strategies.

In Vitro Evaluation of Mucosa Permeation/Retention and Antiherpes Activity of Genistein from Cationic Nanoemulsions.

In this report, we described the genistein distribution on excised porcine esophageal mucosa from cationic nanoemulsions, as well as the anti-HSV-1 activity against a viral strain resistant to acyclovir. Genistein-loaded cationic nanoemulsions were prepared by spontaneous emulsification. This procedure yielded monodisperse nanoemulsions exhibiting a mean droplet size of approximately 200-300 nm. Hydroxyethyl cellulose (HEC) was added at the end of the manufacturing process as a thickening agent (at 3%). Such formulations exhibit a non-Newtonian pseudoplastic behavior. The addition of HEC significantly reduces the genistein flux through excised porcine mucosa specimens as compared with values elicited by nanoemulsions before thickening. Furthermore, a significant increase of genistein retention in mucosa was observed as compared to the genistein propylene glycol solution, as illustrated by confocal fluorescence microscopy images. Formulations exhibited antiherpetic activity in vitro against HSV-1 (strain 29R). Taken together, these results suggest that these formulations have promising potential to be used topically for herpes infections.

Antiherpes evaluation of soybean isoflavonoids.

The antiviral effects of soybean isoflavonoids have been investigated recently, especially those of genistein. It has been reported that this isoflavone is able to inhibit herpes simplex virus (HSV) replication, which is associated with skin and epithelial mucosa infections. The treatment of these infections with antiherpes drugs has resulted in the emergence of resistant viral strains. Based on this evidence, the aim of this study was to investigate the anti-HSV effects of soybean isoflavonoids: daidzein, genistein, glycitein, and coumestrol. Genistein and coumestrol inhibited HSV-1 (KOS and 29R strains, which are acyclovir sensitive and acyclovir resistant, respectively) and HSV-2 (333 strain) replication, whereas no antiviral effects were detected for daidzein and glycitein. The mechanisms of action were evaluated by different methodological strategies. Coumestrol affected the early stages of viral infection, and both compounds were able to reduce HSV-1 protein expression, as well as HSV-2 cell-to-cell spread.

Simultaneous quantification of flavonoids from Achyrocline satureioides by a polar-reversed phase LC method--application to skin permeation/retention studies.

A selective and sensitive polar-reversed phase LC method was validated for simultaneous quantification of the main Achyrocline satureioides flavonoids (quercetin, luteolin, and 3-O-methylquercetin) in skin samples after permeation/retention studies from topical nanoemulsions. The method was linear in a range of 0.25 to 10.0 microg/mL exhibiting a coefficient of determination higher than 0.999 for all flavonoids. No interference of the nanoemulsion excipients or skin components was observed in the retention times of all flavonoids. The R.S.D. values for intra- and inter-day precision experiments were lower than 6.73%. Flavonoids recovery from nanoemulsions and skin matrices was between 90.05 and 109.88%. In a permeation/retention study with porcine ear high amount of 3-O-methylquercetin was found in the skin sample (0.92 +/- 0.22 microg/g) after two hours. The proposed method was suitable to quantify the main flavonoids of A. satureioides in skin permeation/retention studies from topical nanoemulsions.

An HPLC-UV method for the measurement of permeability of marker drugs in the Caco-2 cell assay

The Caco-2 cell line has been used as a model to predict the in vitro permeability of the human intestinal barrier. The predictive potential of the assay relies on an appropriate in-house validation of the method. The objective of the present study was to develop a single HPLC-UV method for the identification and quantitation of marker drugs and to determine the suitability of the Caco-2 cell permeability assay. A simple chromatographic method was developed for the simultaneous determination of both passively (propranolol, carbamazepine, acyclovir, and hydrochlorothiazide) and actively transported drugs (vinblastine and verapamil). Separation was achieved on a C18 column with step-gradient elution (acetonitrile and aqueous solution of ammonium acetate, pH 3.0) at a flow rate of 1.0 mL/min and UV detection at 275 nm during the total run time of 35 min. The method was validated and found to be specific, linear, precise, and accurate. This chromatographic system can be readily used on a routine basis and its utilization can be extended to other permeability models. The results obtained in the Caco-2 bi-directional transport experiments confirmed the validity of the assay, given that high and low permeability profiles were identified, and P-glycoprotein functionality was established.

An HPLC-UV method for the measurement of permeability of marker drugs in the Caco-2 cell assay.

The Caco-2 cell line has been used as a model to predict the in vitro permeability of the human intestinal barrier. The predictive potential of the assay relies on an appropriate in-house validation of the method. The objective of the present study was to develop a single HPLC-UV method for the identification and quantitation of marker drugs and to determine the suitability of the Caco-2 cell permeability assay. A simple chromatographic method was developed for the simultaneous determination of both passively (propranolol, carbamazepine, acyclovir, and hydrochlorothiazide) and actively transported drugs (vinblastine and verapamil). Separation was achieved on a C18 column with step-gradient elution (acetonitrile and aqueous solution of ammonium acetate, pH 3.0) at a flow rate of 1.0 mL/min and UV detection at 275 nm during the total run time of 35 min. The method was validated and found to be specific, linear, precise, and accurate. This chromatographic system can be readily used on a routine basis and its utilization can be extended to other permeability models. The results obtained in the Caco-2 bi-directional transport experiments confirmed the validity of the assay, given that high and low permeability profiles were identified, and P-glycoprotein functionality was established.

LC analysis of coumestrol incorporated into topical lipid nanoemulsions.

A simple, rapid, and sensitive LC method to determine coumestrol incorporated in the lipid nanoemulsions was validated. The analyses were performed at room temperature on a reversed-phase C18 column using a mobile phase composed of methanol/water with 0.1% trifluoracetic acid (70:30, v/v) at 0.8 mL min(-1). The detection was carried out on a UV detector at 343 nm. The linearity, in the range of 0.1-6.0 microg/mL, presented a determination coefficient (r2) of 0.999, calculated by the least square method. No interferences of the oil core or the gelling excipients were detected. The R.S.D. values for intra- and inter-day precision experiments were lower than 2%. The recovery ranged from 99.42% to 100.72%. Finally, the proposed method was successfully applied to determine coumestrol incorporated in the proposed topical formulations.

Development and characterization of parenteral nanoemulsions containing thalidomide.

This study reports the development of nanoemulsions intended for intravenous administration of thalidomide (THD). The formulations were prepared by spontaneous emulsification method and optimized with respect to thalidomide (0.01-0.05%, w/w), and hydrophilic emulsifier (polysorbate 80; 0.5-4.0%, w/w) content. The formulations were evaluated concerning physical appearance and drug crystallization; droplet size; zeta potential and drug assay. Only the formulation containing 0.01% THD and 0.5% polysorbate kept its properties in a satisfactory range over the evaluated period (60 days), i.e. droplet size around 200nm, drug content around 95% and zeta potential around -30mV. The transmission electron microscopy revealed emulsion droplets almost spherical in shape confirming the results obtained by photon correlation spectroscopy. Drug crystallization observed for higher content (THD 0.05%, w/w) nanoemulsions was investigated. The crystals observed at optical microscopy presented a different crystal habit compared to that of the raw material used. It was speculated whether the kind of THD polymorph employed could influence nanoemulsion formulation. Formulations were prepared with either one of THD polymorphs (ß- or α-) and crystals were characterized by fourier transformed infrared spectroscopy (FTIR) and X-ray diffraction (XRD). It was observed that regardless of the polymorph employed (ß- or α-), drug crystallization occurs in the α-form. THD solubility in oils was not influenced by the polymorphic form. In addition, the in vitro dissolution profile of the selected formulation (THD 0.01%, w/w; polysorbate 0.5%, w/w) was assessed by bulk-equilibrium reverse dialysis sac technique and demonstrated a release profile similar to that of a THD acetonitrile solution, with around 95% THD being dissolved within 4h. Finally, a pharmacokinetic simulation of an intravenous infusion of 250mL of the selected nanoemulsion suggests that the parenteral administration of a dose as low as 25mg might lead to therapeutic plasma concentrations of thalidomide.

Development and validation of a LC method for determination of genistein in topical nanoemulsions.

The aim of this study was to develop and validate an isocratic LC method for the quantification of genistein in topical nanoemulsions. The analyses were performed at room temperature on a reversed-phase C18 column using a mobile phase composed of methanol/water/acetonitrile (70:25:5, w/w/w) at 1.0 ml x min(-1). The detection was carried out on a UV detector at 327 nm. The linearity, in the range of 25-75 microg/ml, presented a determination coefficient (r2) higher than 0.999, calculated by the least square method. No interferences from the excipients (egg-lecithin, octyldodecanol or medium chain triglycerides) were detected. The R.S.D. values for intra- and inter-day precision experiments were lower than 2.3%. The recovery of genistein from nanoemulsions ranged from 96.6% to 106.6%. The excellent performance of the method, its linearity, accuracy and precision, demonstrate that it can be readily used to quantify genistein incorporated in nanoemulsions.

Carbamazepine/betaCD/HPMC solid dispersions. II. Physical characterization.

Solid dispersions containing carbamazepine (CBZ) associated with beta-cyclodextrin (betaCD) and/or hydroxypropyl methylcellulose were prepared by two different methods, spray-drying or physical mixture, and characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), infrared (IR) spectroscopy, and x-ray powder diffraction analysis (XRPD) studies. Scanning electron microscopy pictures showed that spray-drying produced a mixture of hollow, spherical, and partially shrunken microparticles of homogeneous materials, whereas the physical mixtures yielded heterogeneous systems in which all individual components could be identified. Thermal and IR analyses suggest the existence of a strong interaction between CBZ and excipients in spray-dried solid dispersions, but no CBZ polymorphic transition was detected by either IR spectroscopy or XRPD analysis after the spray-drying process.

Ofloxacin/beta-cyclodextrin complexation.

Ofloxacin (OFX) is a fluorquinolone characterized by photochemical instability. With the goal to improve its photostability in aqueous solutions, the complexation of ofloxacin with beta-cyclodextrin was investigated. The complexes showed a water solubility enhancement of approximately 2.6 times; nevertheless, the photodegradation of ofloxacin was not reduced. The complexes obtained were characterized by thermal and 1H nuclear magnetic resonance (NMR) analysis, which revealed an interaction between ofloxacin and beta-cyclodextrin. The last analysis indicated that only partial inclusion of the N-methylpiperazinyl moiety occurred, which can explain the fact that photostabilization was not improved. This partial inclusion phenomenon could be explained also by computer-aided molecular modeling.

Tactile Contact by Deaf and Hearing Mothers During Face-to-Face Interactions With Their Infants.

Tactile contact with an infant plays an important role (though one largely overlooked by researchers until recently) in the development of synchronous interactive dialogues between caregiver and child. Dyads in which one or both partners are deaf present a unique opportunity to examine the use of touch as a means of optimizing or enhancing communication when the number of available sensory channels is restricted. Touch in these dyads may play an important role in eliciting visual attention, in alerting the infant that signed communication is forthcoming, in assisting the infant to achieve emotional regulation, or in simply maintaining contact even when the deaf child has looked away from the partner. The data presented here represent one attempt to investigate the role of touch in relation to deaf infants and deaf parents, for whom it may play a particularly salient role. Both deaf and hearing mothers were observed in videotaped face-to-face interactions with their infants (also either deaf or hearing); maternal behavior was coded for each event during which mothers initiated tactile contact with the infant and was classified according to intensity, location on the infant's body, and type of touch (e.g., active vs. passive). Results of this study indicate that deaf mothers may be especially responsive to the tactile needs of their deaf infants, as shown by qualitative differences in their behavioral interactions with 6- and 9-month-olds. However, hearing mothers with deaf infants also appear to be incorporating more active forms of touch in their interactions, although they tend to rely on longer durations of tactile contact than do the deaf mothers.

Responses to interactive stress: infants who are deaf or hearing.

Nineteen infants who were deaf (D/H) and 19 infants who were hearing (H/H) were observed during face-to-face interactions with their hearing mothers. Infant behaviors were coded for repetitive physical activity and gaze aversion during two episodes of normal play which were interrupted by a "still-face" episode. Mothers' assessments of their infants as "difficult" or "easy" were derived from the Parenting Stress Index (Abidin, 1986). "Difficult" deaf infants displayed significantly more repetitive activity during the initial normal interaction and significantly more gaze aversion during the still-face episode, compared to "easy" deaf babies and both "easy" and "difficult" hearing babies. Implications of these findings are discussed in the context of parental perceptions of infant behaviors, and the importance of visual attention and nonverbal signals for the optimal development of infants who are deaf.

How do deaf and hearing mothers regain eye contact when their infants look away?

The authors examine the effects that results when 9-month-old deaf and hearing infants break eye contact during face-to-face interactions with their deaf or hearing mothers. Of particular interest are mothers' responses when their infant looks away, and mothers' degree of success at regaining visual attention by using active bids in either the tactile, visual, or auditory modes. The authors also examine instances of maternal observing and waiting for the infant to reinitiate visual contact. For deaf infants, visual and tactile modalities are particularly important for communicating, interacting, and gaining information about their environment. While hearing parents have been shown to compensate intuitively for a deaf child's inability to perceive auditory cues (Koester, 1992, 1995), deaf parents may offer important insights into the use of other modalities to elicit and maintain a deaf infant's attention. Results of the study indicate a greater reliance among deaf mothers on visual strategies to regain infant attention, and a greater emphasis on vocalizations by hearing mothers, regardless of infant hearing status.

Defining and observing social signals in deaf and hearing infants.

Infant gaze, gestures, and affective expression have become generally accepted as indicators of the infant's efforts to initiate or resume interaction with a partner, particularly during moments when the mother may be temporarily unresponsive as shown experimentally in the maternal "Still-Face" situation. Previous studies comparing deaf and hearing infants using this paradigm have revealed diminished signalling by deaf infants with hearing mothers, when signals were defined by the typical indices mentioned above. This study compares results from both a microanalytic coding system (used with 59 dyads) and a more global examination of efforts by 20 deaf and 20 hearing infants to re-engage their deaf or hearing mothers. Emphasis is on the kinds of infant signals that often remain undocumented due to methodological constraints, but that may be recognized by the mother and elicit a delayed response from her when she is able to resume her normal interactive patterns. Results indicate that when these additional "signal" behaviors are considered (such as repetitive hand, arm, or foot movements, or behaviors previously prohibited by the mother), there are few overall differences in eliciting efforts by deaf and hearing infants.

Communicative interactions of deaf and hearing children in a day care center. An exploratory study.

Interactions were observed in a day care center serving deaf and hearing children. Observations focused on eight children (two deaf with deaf parents, two deaf with hearing parents, two hearing with deaf parents and two hearing with hearing parents) between 2 and 3 years of age. Center classes included deaf and hearing teachers and all children were encouraged to sign. Deaf and hearing children alike frequently interacted with other children and teachers whose hearing status differed from their own. However, each group showed a stronger tendency to initiate communication with same hearing status peers. Hearing children displayed the ability to modify their communications modes to match the hearing status of their intended communication partner. Language ability, not hearing status, was associated with the frequency of communication experienced by each child.

Social support, motivation, language, and interaction. A longitudinal study of mothers and deaf infants.

This project examined the effect of early cognitive, social, and communicative experiences on later social and language development in deaf infants with hearing mothers. Interactions between mothers and deaf infants were found to be positively influenced by social support provided to mothers in the early months of the infants' lives, mothers' visual and tactile responsiveness when their infants were 9 months of age, infants' ability to cope with interactive stress at 9 months of age, and fewer attempts by infants to engage with the social environment during the mastery motivation assessment at 9 months of age. Neither mother-infant affective matching nor maternal visual-tactile responsiveness correlated with the deaf infants' language level.

Intuitive parenting as a model for understanding parent-infant interactions when one partner is deaf.

This paper reviews the concept of intuitive parenting, with particular focus on its applicability to parent-infant dyads in which the parent or child is deaf. Although the conceptual model discussed in this paper was developed primarily from observations of hearing dyads, it has the potential to contribute to our understanding of early adaptive processes in other populations as well. Examples of nonconscious or intuitive parental behaviors are presented in terms of the ways they help infants adapt to the postnatal environment and in the later transition from preverbal to verbal stages of development. In addition, implications are drawn for difficulties in parent-infant interactions that may occur as a result of deafness in the parent or child.