Efficacy of an organically modified bentonite to adsorb 2,4-dichlorophenoxyacetic acid (2,4-D) and prevent its phytotoxicity

The herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) is widely used due to it selective action, and preferential control of dicotyledonous weeds affecting cereal crops. Physiological responses of sensitive dicotyledonous plants to 2,4-D include growth retardation, senescence, and cell death. Due to soil and water contamination by agricultural practices, 2,4-D constitutes a potential risk to non-target plant species. In this work, the potential advantage of using organic modified bentonite (Bent) to adsorb 2,4-D and therefore mitigate damage produced by this herbicide on sensitive not-target vegetable species was investigated. Dodecylamine (DDA) was used as an organic modifier to change the hydrophilic nature of Bent into an organophilic matrix. The adsorption performances of 2,4-D by Bent-DDA were analyzed. The maximum adsorptions of 2,4-D (22.1 mg/L) from aqueous solution containing 1.0 or 2.5 mg/mL Bent-DDA were 40 and 80 %, respectively. The physical interaction of Bent-DDA with 2,4-D was characterized by Wide Angle X-ray Scattering (WAXS) and thermogravimetric analysis (TGA). The biological functionality of Bent-DDA matrix as 2,4-D adsorbent was tested in a bioassay in the Arabidopsis thaliana plant model system. The primary root growth of Arabidopsis seedlings is strongly inhibited by low concentrations of 2,4-D. Arabidopsis seedlings submitted to Bent-DDA pre-treated herbicide aqueous solution showed similar root growth than 2,4-D non-treated seedlings. Finally, the ability of Bent-DDA to prevent 2,4-D phytotoxicity was exploratory investigated in lettuce plants. Lettuce plants pre-treated with 20 μg/mL Bent-DDA showed reduced sensitivity to 2,4-D including an increment on chlorophyll content and biomass compared with non-treated plants. Our findings revealed a promising scenario for the application of Bent-DDA as an effective adsorbent of 2,4-D at productive scale.

Design of magnetic hybrid nanostructured lipid carriers containing 1,8-cineole as delivery systems for anticancer drugs: Physicochemical and cytotoxic studies

The development of versatile carriers to deliver chemotherapeutic agents to specific targets with establishing drug release kinetics and minimum undesirable side effects is becoming a promising relevant tool in the medical field. Magnetic hybrid nanostructured lipid carriers (NLC) were prepared by incorporation of 1,8-cineole (CN, a monoterpene with antiproliferative properties) and maghemite nanoparticles (MNPs) into a hybrid matrix composed of myristyl myristate coated with chitosan. Hybrid NLC characterized by DLS and TEM confirmed the presence of positively charged spherical nanoparticles of around 250 nm diameter and +10.2 mV of Z-potential. CN encapsulation into the lipid core was greater than 75 % and effectively released in 24 h. Modification of the crystalline structure of nanoparticles after incorporation of CN and MNPs was observed by XRD, DSC, and TGA analyses. Superparamagnetic NLC behavior was verified by recording the magnetization using a vibrating scanning magnetometer. NLC resulted in more cytotoxic than free CN in HepG2 and A549 cell lines. Particularly, viability inhibition of HepG2 and A549 cells was increased from 35 % to 55 % and from 38 % to 61 %, respectively, when 8 mM CN was incorporated into the lipid NPs at 24 h. Green fluorescent-labeled NLC with DIOC18 showed an enhanced cellular uptake with chitosan-coated NLC. Besides, no cytotoxicity of the formulations in normal WI-38 cells was observed, suggesting that the developed hybrid NLC system is a safe and good potential candidate for the selective delivery and potentiation of anticancer drugs.

RONC-17. STEREOTACTIC RADIOSURGERY FOR SPINE METASTASES IN PEDIATRIC MALIGNANCIES

BACKGROUND

Spine stereotactic radiosurgery (SSRS) is a non-invasive technique that delivers ablative radiotherapy for optimal control of bony disease. While SSRS is known to provide excellent local control (LC) and minimal toxicity in adults, the role of SSRS in pediatrics is less clear.

PURPOSE

To evaluate SSRS in pediatric patients with spinal metastases.

METHODS

A retrospective review of patients (<18 yrs) treated with SSRS at MDACC was performed after IRB approval. Descriptive statistics were utilized for analysis.

RESULTS

From 2011–2019, 12 metastatic osseous sites (3 cervical, 4 thoracic, 5 lumbar-sacral) in 9 patients were treated. Median follow-up was 9 months (range 2–41). Six males (67%) and 3 females (33%) all KPS ≥70, received radiation to ≤3 contiguous vertebral bodies. Median age was 16 yrs (range 8–18). No patients required sedation. Histologies included 7 osteosarcomas, one rhabdomyosarcoma and one Ewing’s sarcoma. Metastatic epidural spinal cord compression scores ranged from 0 (6), 1b (3) and 3 (3). No sites had surgery prior to SSRS and one site received prior conventional radiation. SSRS doses included 24 Gy in 1 fraction (7), 24–27 Gy in 3 fractions (4) and 50 Gy in 5 fractions (1). Six-month LC was 83% with one local failure following 27 Gy. OS at 6 and 12 mo were 55% and 23%. There was no grade ≥3 acute toxicity, no radiation myelopathy or vertebral compression fractures.

CONCLUSION

In this initial report, SSRS represents a promising modality that is well tolerated and provides excellent LC. However, further follow-up is warranted in the pediatric setting.

Hybrid Ofloxacin/eugenol co-loaded solid lipid nanoparticles with enhanced and targetable antimicrobial properties

In the global context of an imminent emergence of multidrug-resistant microorganisms, the present work combined the use of nanotechnology and the therapeutic benefits of natural compounds as a strategy to potentiate antimicrobial action of the wide-spectrum antibiotic Ofloxacin (Ofx). Hybrid solid lipid nanoparticles (SLN) were synthesized by incorporation of chitosan (Chi, a cationic biopolymer with antimicrobial activity) and eugenol (Eu, a phenolic compound that interferes with bacterial quorum sensing) into a lipid matrix by hot homogenization/ultrasonication method. The developed SLN/Chi/Eu sustainably released the encapsulated Ofx for 24 h. Characterization by DLS, TEM, DSC, TGA and XRD revealed the presence of positively charged spherical nanoparticles with diameters around 300 nm and Ofx entrapped in amorphous state. The SLN exhibited an enhanced bactericidal activity against Pseudomonas aeruginosa and Staphylococcus aureus. The minimum inhibitory concentration (MIC) for free and nanoencapsulated Ofx formulations was below 1.0 µg/ml. The MIC values decreased by 6.1- to 16.1-fold when Ofx was encapsulated in SLN/Chi/Eu. Fluorescent-labeled nanoparticles had the ability to interact with the bacterial cell membrane. Selective toxicity of SLN/Chi/Eu-Ofx was tested in the range of 0.3-30.0 µg/ml and showed no toxicity up to 3.0 µg/ml Ofx in human cell models (A549 and Wi-38) at 24 h and 48 h exposure. It was proved that the administration of hybrid SLN to mice by dry powder inhalation reached therapeutic Ofx levels in lungs.

Genetic inhibition of neurotransmission reveals role of glutamatergic input to dopamine neurons in high-effort behavior

Midbrain dopamine neurons are crucial for many behavioral and cognitive functions. As the major excitatory input, glutamatergic afferents are important for control of the activity and plasticity of dopamine neurons. However, the role of glutamatergic input as a whole onto dopamine neurons remains unclear. Here we developed a mouse line in which glutamatergic inputs onto dopamine neurons are specifically impaired, and utilized this genetic model to directly test the role of glutamatergic inputs in dopamine-related functions. We found that while motor coordination and reward learning were largely unchanged, these animals showed prominent deficits in effort-related behavioral tasks. These results provide genetic evidence that glutamatergic transmission onto dopaminergic neurons underlies incentive motivation, a willingness to exert high levels of effort to obtain reinforcers, and have important implications for understanding the normal function of the midbrain dopamine system.

Carbamazepine-loaded solid lipid nanoparticles and nanostructured lipid carriers: Physicochemical characterization and in vitro/in vivo evaluation

Solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) represent promising alternatives for drug delivery to the central nervous system. In the present work, four different nanoformulations of the antiepileptic drug Carbamazepine (CBZ) were designed and prepared by the homogenization/ultrasonication method, with encapsulation efficiencies ranging from 82.8 to 93.8%. The formulations remained stable at 4 °C for at least 3 months. Physicochemical and microscopic characterization were performed by photon correlation spectroscopy (PCS), transmission electron microscopy (TEM), atomic force microscopy (AFM); thermal properties by differential scanning calorimetry (DSC), thermogravimetry (TGA) and X-ray diffraction analysis (XRD). The results indicated the presence of spherical shape nanoparticles with a mean particle diameter around 160 nm in a narrow size distribution; the entrapped CBZ displayed an amorphous state. The in vitro release profile of CBZ fitted into a Baker-Lonsdale model for spherical matrices and almost the 100% of the encapsulated drug was released in a controlled manner during the first 24 h. The apparent permeability of CBZ-loaded nanoparticles through a cell monolayer model was similar to that of the free drug. In vivo experiments in a mice model of seizure suggested protection by CBZ-NLC against seizures for at least 2 h after intraperitoneal administration. The developed CBZ-loaded lipid nanocarriers displayed optimal characteristics of size, shape and drug release and possibly represent a promising tool to improve the treatment of refractory epilepsy linked to efflux transporters upregulation.

Correction: Genetic inhibition of neurotransmission reveals role of glutamatergic input to dopamine neurons in high-effort behavior

In Figure 1e and f, "F4 control" should be "Cre/tdTomato" and "F4Cre KO" should be "F4Cre/tdTomato". In addition, in the Figure1f legend, the first sentence should end with "(Cre/tdTomato: n = 10, F4Cre/tdTomato: n = 14)".In the 'Materials and Methods' section, under 'Electrophysiology,' the n values for evoked action potential recordings were omitted. The sentence 'For high-frequency stimulus-induced action potentials, the stimulus electrode was placed in the rostral part of VTA and a train of 100 Hz stimuli (1 s) was applied' should end with '(Cre/tdTomato: n=10, F4Cre/tdTomato: n=14).'Later in the same paragraph, in 'For recording evoked EPSCs (Cre/tdTomato, n=13, F4Cre/tdTomato, n=15; AMPA EPSCs were recorded at -70  mV and NMDA EPSCs were recorded at +40 mV)', the phrase 'Cre/tdTomato, n=13, F4Cre/tdTomato, n=15' should be deleted; those n values should have appeared at the end of the later sentence beginning 'Miniature ESPCs...'. The complete, corrected sentence is 'Miniature EPSCs (mEPSCs) were acquired in the presence of 0.5-1 μM TTX and 100 μM picrotoxin and semiautomatically detected by offline analysis using in-house software in Igor Pro (Wavemetrics, Portland, OR, USA) (Cre/tdTomato, n=13, F4Cre/tdTomato, n=15).'Finally, in the 'Materials and Methods' section, third sentence under 'Immunohistochemistry,' information for one TH antibody was omitted. The list of antibodies should end with 'or Millipore MAB5280, 1:1000-1:2000.'

ErbB4 signaling in dopaminergic axonal projections increases extracellular dopamine levels and regulates spatial/working memory behaviors

Genetic variants of Neuregulin 1 (NRG1) and its neuronal tyrosine kinase receptor ErbB4 are associated with risk for schizophrenia, a neurodevelopmental disorder characterized by excitatory/inhibitory imbalance and dopamine (DA) dysfunction. To date, most ErbB4 studies have focused on GABAergic interneurons in the hippocampus and neocortex, particularly fast-spiking parvalbumin-positive (PV+) basket cells. However, NRG has also been shown to modulate DA levels, suggesting a role for ErbB4 signaling in dopaminergic neuron function. Here we report that ErbB4 in midbrain DAergic axonal projections regulates extracellular DA levels and relevant behaviors. Mice lacking ErbB4 in tyrosine hydroxylase-positive (TH+) neurons, but not in PV+ GABAergic interneurons, exhibit different regional imbalances of basal DA levels and fail to increase DA in response to local NRG1 infusion into the dorsal hippocampus, medial prefrontal cortex and dorsal striatum measured by reverse microdialysis. Using Lund Human Mesencephalic (LUHMES) cells, we show that NRG/ErbB signaling increases extracellular DA levels, at least in part, by reducing DA transporter (DAT)-dependent uptake. Interestingly, TH-Cre;ErbB4^f/f mice manifest deficits in learning, spatial and working memory-related behaviors, but not in numerous other behaviors altered in PV-Cre;ErbB4^f/f mice. Importantly, microinjection of a Cre-inducible ErbB4 virus (AAV-ErbB4.DIO) into the mesencephalon of TH-Cre;ErbB4^f/f mice, which selectively restores ErbB4 expression in DAergic neurons, rescues DA dysfunction and ameliorates behavioral deficits. Our results indicate that direct NRG/ErbB4 signaling in DAergic axonal projections modulates DA homeostasis, and that NRG/ErbB4 signaling in both GABAergic interneurons and DA neurons contribute to the modulation of behaviors relevant to psychiatric disorders.

Restructuring of basal ganglia circuitry and associated behaviors triggered by low striatal D2 receptor expression: implications for substance use disorders

Dopamine D2 receptors (D2Rs) consistently emerge as a critical substrate for the etiology of some major psychiatric disorders. Indeed, a central theory of substance use disorders (SUDs) postulates that a reduction in D2R levels in the striatum is a determining factor that confers vulnerability to abuse substances. A large number of clinical and preclinical studies strongly support this link between SUDs and D2Rs; however, identifying the mechanism by which low D2Rs facilitate SUDs has been hindered by the complexity of circuit connectivity, the heterogeneity of D2R expression and the multifaceted constellation of phenotypes observed in SUD patient. Animal models are well‐suited for understanding the mechanisms because they allow access to the circuitry and the genetic tools that enable a dissection of the D2R heterogeneity. This review discusses recent findings on the functional role of D2Rs and highlights the distinctive contributions of D2Rs expressed on specific neuronal subpopulations to the behavioral responses to stimulant drugs. A circuit‐wide restructuring of local and long‐range inhibitory connectivity within the basal ganglia is observed in response to manipulation of striatal D2R levels and is accompanied by multiple alterations in dopamine‐dependent behaviors. Collectively, these new findings provide compelling evidence for a critical role of striatal D2Rs in shaping basal ganglia connectivity; even among neurons that do not express D2Rs. These findings from animal models have deep clinical implications for SUD patients with low levels D2R availability where a similar restructuring of basal ganglia circuitry is expected to take place.

Expression of connexins during development and following manipulation of afferent input in the rat locus coeruleus

Synchronous activity of locus coeruleus (LC) neurons during early postnatal development is regulated, in part, by electrotonic coupling. Connexin (Cx) proteins that make up gap junction channels are localized to both neurons and glia in the LC during this period. In adult rats, however, synchrony exists only under certain experimental conditions. The expression of Cx proteins was examined using western blot analysis at several developmental time points. Immunoblot analysis revealed little to no expression of Cx26 while Cx32, Cx43 and Cx36 were present at all time points examined. A progressive increase in Cx43 was identified from the first postnatal week through adulthood. Immunocytochemical detection of Cx36 and Cx43 in adult LC showed that Cx36 was associated with neuronal processes while Cx43 was localized to glia. In adult LC, in vitro intracellular recordings combined with neurobiotin injections confirmed the presence of gap junctional communication albeit to a lesser extent than in early postnatal periods. The degree to which synaptic inputs to LC neurons impact on Cx protein expression was also evaluated. Samples of the LC from rats that received an electrolytic lesion of the amygdala were processed for western blot analysis of Cx36 and Cx43. The predominantly neuronal Cx36 exhibited an increase in expression while the glial Cx43 was unchanged. The present results indicate that, despite subtype-specific changes during development, several Cx proteins are expressed in the adult LC. In addition, manipulating afferent input to the LC, in adult rats, results in increases in neuronal Cx protein levels but not in glial Cx levels suggesting that altering synaptic inputs to the LC may alter synchronous activity in noradrenergic neurons.

[Cystine calculi: x-ray diffraction study. Infrared spectroscopy and SEM]

The present study investigated cystinuria and cystine calculi. Inexplicably, of 987 calculi that had been analyzed ultrastructurally at the Department of Urology of the University Hospital of Salamanca over a period of 15 years only 3 (0.3%) were cystine. The foregoing finding does not coincide with the 0.5-1% incidence reported in the world literature. Apart from the chemical analyses, infrared spectroscopy disclosed the typical findings of multiple bands 1600-625 cm-1. Analysis by x-ray diffraction revealed a slight variation from the ASTM values. One of the calculi, which we considered to be a mixed calculus (probably of calcium phosphate), showed a peak at 43 degrees, instead of the usual 34.5. Scanning electron microscopy disclosed two forms of crystallization: The typical hexagonal form of cystine stones and the rectangular form of different sizes. The material comprising the matrix was observed in many areas, covering and joining the crystals as if it were cement. Whenever possible, treatment of these recurrent calculi should be conservative. Some advocate the use of ESWL, although others consider these calculi to be extremely hard and, therefore, not amenable to ESWL. Chemical dissolution is advocated by some, although its critics consider it to be of little use. Concerning prophylaxis, forced fluids and alkalinization may reduce recurrence. Ultrastructural studies have provided further insight into the structure and composition of cystine calculi. The foregoing may be useful in determining the most appropriate form of treatment based upon stone size, shape, composition (pure or mixed), etc.