Modification of the Luedeking and Piret model with a delay time parameter for biotechnological lactic acid production.

OBJECTIVES: To obtain a mathematical model that adequately describes the time lag between biomass generation and lactic acid production of lactic fermentations. METHODS: Seven experimental kinetics from other research works were studied to validate our proposal: four studies of Fungal Submerged Fermentation and three cases of Bacterial Submerged Fermentation, including the data recollected by Luedeking and Piret. RESULTS: We introduce a modification to the Luedeking and Piret model that consist in the introduction of a time delay parameter in the model, this parameter would account for the lag time that exists between the production of biomass and lactic acid. It is possible to determine this time delay in a simple way by approximating the biomass and product formation considering that they behave as a first order plus dead time system. The duration of this phenomenon, which is not described with the classical Luedeking and Piret model, is a function of microorganism physiology (ease of biomass growth), environment (nutrients) and type of inoculum. CONCLUSION: The Luedeking and Piret with delay model applications reveal an increase of the R2 in all cases, evidencing the quality of fit and the simplicity of the method proposed. These model would improve the accuracy of bioprocess scaling up.

Convection-enhanced delivery and in vivo imaging of polymeric nanoparticles for the treatment of malignant glioma.

A major obstacle to the management of malignant glioma is the inability to effectively deliver therapeutic agent to the tumor. In this study, we describe a polymeric nanoparticle vector that not only delivers viable therapeutic, but can also be tracked in vivo using MRI. Nanoparticles, produced by a non-emulsion technique, were fabricated to carry iron oxide within the shell and the chemotherapeutic agent, temozolomide (TMZ), as the payload. Nanoparticle properties were characterized and subsequently their endocytosis-mediated uptake by glioma cells was demonstrated. Convection-enhanced delivery (CED) can disperse nanoparticles through the rodent brain and their distribution is accurately visualized by MRI. Infusion of nanoparticles does not result in observable animal toxicity relative to control. CED of TMZ-bearing nanoparticles prolongs the survival of animals with intracranial xenografts compared to control. In conclusion, the described nanoparticle vector represents a unique multifunctional platform that can be used for image-guided treatment of malignant glioma. FROM THE CLINICAL EDITOR: GBM remains one of the most notoriously treatment-unresponsive cancer types. In this study, a multifunctional nanoparticle-based temozolomide delivery system was demonstrated to possess enhanced treatment efficacy in a rodent xenograft GBM model, with the added benefit of MRI-based tracking via the incorporation of iron oxide as a T2* contrast material in the nanoparticles.

The effect of ultrasound stimulation on the cytoskeletal organization of chondrocytes seeded in three-dimensional matrices.

The impact of low-intensity diffuse ultrasound (LIDUS) stimulation on the cytoskeletal organization of chondrocytes seeded in three-dimensional (3D) scaffolds was evaluated. Chondrocytes seeded on 3D chitosan matrices were exposed to LIDUS at 5.0 MHz (approx. 15 kPa, 51 s, 4 applications/day) in order to study the organization of actin, tubulin and vimentin. The results showed that actin presented a punctate cytosolic distribution and tubulin presented a quasiparallel organization of microtubules, whereas vimentin distribution was unaffected. Chondrocytes seeded on 3D scaffolds responded to US stimulation by the disruption of actin stress fibers and were sensitive to the presence of Rho-activated kinase (ROCK) inhibitor (Y27632). The gene expression of ROCK-I, a key element in the formation of stress fibers and mDia1, was significantly upregulated under the application of US. We conclude that the results of both the cytoskeletal analyses and gene expression support the argument that the presence of punctate actin upon US stimulation was accompanied by the upregulation of the RhoA/ROCK pathway.

Effect of fiber diameter on the spreading, proliferation and differentiation of chondrocytes on electrospun chitosan matrices.

Tissue-engineered neocartilage with appropriate biomechanical properties holds promise not only for graft applications but also as a model system for controlled studies of chondrogenesis. Our objective in the present research study is to better understand the impact of fiber diameter on the cellular activity of chondrocytes cultured on nanofibrous matrices. By using the electrospinning process, fibrous scaffolds with fiber diameters ranging from 300 nm to 1 µm were prepared and the physicomechanical properties of the scaffolds were characterized. Bovine articular chondrocytes were then seeded and maintained on the scaffolds for 7 and 14 days in culture. An upregulation in the gene expression of collagen II was noted with decreasing fiber diameters. For cells that were cultured on scaffolds with a mean fiber diameter of 300 nm, a 2-fold higher ratio of collagen II/collagen I was noted when compared to cells cultured on sponge-like scaffolds prepared by freeze drying and lyophilization. Integrin (α(5), αv, ß(1)) gene expression was also observed to be influenced by matrix morphology. Our combined results suggest that matrix geometry can regulate and promote the retention of the chondrocyte genotype.

Preparation and characterization of bosentan monohydrate/ε-polycaprolactone nanoparticles obtained by electrospraying.

The electrospraying technique provides nano and microparticles that can be used as drug delivery systems. The aims of this study were, firstly, to optimize the influent parameters of electrospraying for the manufacture of a Bosentan (BOS) nanoparticulate platform, and secondly, to evaluate its physicochemical properties and in vitro biopharmaceutical behavior. Particles were characterized by scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), thermogravimetry (TG) and Fourier transformed Infrared spectroscopy (FTIR). Drug loading, encapsulation efficiency and kinetic dissolution were determined. Additionally, Bosentan release assays at 24 and 72 h were performed in vitro to evaluate biopharmaceutical properties of nano-scaffolds by diffusion technique through dialysis bag. The nanostructures had heterogeneous sizes predominantly smaller than 550 nm and they were semicrystalline according to PXRD, indicating a partial amorphization of BOS during the encapsulation in the polymer matrix. FT-IR and DSC showed an absence of chemical interactions between BOS and ε-Polycaprolactone (PCL), suggesting that both components behaved as a physical mixture in these particles. The drug loading was 25.98%, and the encapsulation efficiency was 58.51%. Additionally, the release assays showed an extended and controlled release of BOS, in comparison to non-encapsulated BOS. These data also showed to fit with the Cubic Root kinetic dissolution. As a conclusion, we demonstrate that the use of electrospraying for the manufacture of BOS (or similar drugs) controlled release nanoplatforms would represent an interesting contribution in the development of new therapeutic alternatives for the treatment of pathologies such as pulmonary hypertension and other related diseases. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 35: e2748, 2019.

Glucosamine/L-lactide copolymers as potential carriers for the development of a sustained rifampicin release system using Mycobacterium smegmatis as a tuberculosis model.

The present study aims at developing a new, ultrafine particle-based efficient antibiotic delivery system for the treatment of tuberculosis. The carrier material to make the rifampicin (RIF)-loaded particles is a low molecular weight star-shaped polymer produced from glucosamine (core building unit) and L-lactide (GluN-LLA). Particles were made via electrohydrodynamic atomization. Prolonged release (for up to 14 days) of RIF from these particles is reported. Drug release data fits the Korsmeyer-Peppas equation, which suggests the occurrence of a modified diffusion-controlled RIF release mechanism in vitro and is also supported by differential scanning calorimetry and drug leaching tests. Cytotoxicity tests on Mycobacterium smegmatis showed that antibiotic-free GluN-LLA and polylactides (PLA) particles (reference materials) did not show any significant anti-bacterial activity. The minimum inhibitory concentration and minimum bactericidal concentration values obtained for RIF-loaded particles showed 2- to 4-fold improvements in the anti-bacterial activity relative to the free drug. Cytotoxicity tests on macrophages indicated that cell death correlates with an increase of particle concentration but is not significantly affected by material type or particle size. Confocal microscopy was used to track internalization and localization of particles in the macrophages. The uptake of GluN-LLA particles is higher than those of their PLA counterparts. In addition, after phagocytosis, the GluN-LLA particles stayed in the cytoplasm and showed favorable long-term drug release behavior, which facilitated the killing of intracellular bacteria when compared to free RIF. The present studies suggest that these drug carrier materials are potentially very attractive candidates for the development of high-payload, sustained-release antibiotic/resorbable polymer particle systems for treating bacterial lung infections.

Biocompatible and biodegradable ultrafine fibrillar scaffold materials for tissue engineering by facile grafting of L-lactide onto chitosan.

A chitosan derivative was prepared with good yields using a "one pot" approach by grafting L-lactide oligomers via ring opening polymerization. Side chains are primarily attached to hydroxyl groups located on carbons 3 and 6 of the glucosamine ring, while the amine group remains nonfunctionalized. By increasing the L-lactide to chitosan ratio, side chain length is controlled. This allows the manipulation of the biodegradation rate and hydrophilicity of the tissue engineering scaffold material. This general synthetic route renders functionalized chitosan soluble in a broad range of organic solvents, facilitating formation of ultrafine fibers via electrospinning. Cytotoxicity tests using fibroblasts (L929 cell line) performed on electrospun L-lactide modified chitosan fibers showed that the specimen with the highest molar ratio of L-lactide (1:24) investigated in this study is the most promising material for tissue engineering purposes, while less stable formulations might still find application in drug delivery vehicles.

Anandamide and endocannabinoid system: an attractive therapeutic approach for cardiovascular disease.

Cardiovascular disease is currently not adequately managed and has become one of the main causes of morbidity and mortality worldwide. Current therapies are inadequate in terms of preventing its progression. There are several limitations, such as poor oral bioavailability, side effects, low adherence to treatment, and high dosage frequency of formulations due to the short half-life of the active ingredients used, among others. This review aims to highlight the most relevant aspects of the relationship between the cardiovascular system and the endocannabinoid system, with special attention to the possible translational effect of the use of anandamide in cardiovascular health. The deep and detailed knowledge of this interaction, not always beneficial, and that for years has gone unnoticed, is essential for the development of new therapies. We discuss the most recent and representative results obtained in the field of basic research, referring to the aforementioned subject, emphasizing fundamentally the main role of nitric oxide, renal physiology and its deregulation in pathological processes.

Intermittent applications of continuous ultrasound on the viability, proliferation, morphology, and matrix production of chondrocytes in 3D matrices.

Chondrocytes, the cellular component of the articular cartilage, have long been recognized as strain-sensitive cells, and have the ability to sense mechanical stimulation through surface receptors and intracellular signaling pathways. This strain-induced biological response of chondrocytes has been exploited to facilitate chondrocyte culture in in vitro systems; examples include the application of hydrostatic pressure, dynamic compression, hydrodynamic shear (i.e., rotating bioreactors), and low-intensity pulsed ultrasound (US). While the ability of US to influence chondrogenesis has been documented, the precise mechanisms of US-induced stimulation continue to be investigated. There remains a critical need to evaluate the impact of US on chondrocytes in 3D culture, which is a necessary microenvironment for maintaining the chondrocyte phenotype. In this study, a continuous US wave for predetermined time intervals was employed, as opposed to pulsed US used in previous studies, to stimulate chondrocytes seeded in 3D scaffolds. The chondrocytes (n = 6) were subjected to US stimulation as follows: 1.5 MHz for 161 seconds, 5.0 MHz for 51 seconds, and 8.5 MHz for 24 seconds, and the US signal was applied twice in a 24-hour period. Scaffolds that are not stimulated by US served as the control. Both the control and the US-stimulated groups were maintained in culture for 10 days, and at the conclusion of the culture period, chondrocytes were assayed for total DNA content, morphology, and cartilage-specific gene expression by reverse transcriptase polymerase chain reaction. Our results show that chondrocytes when stimulated with continuous US for predetermined time intervals possessed higher cellular viability (1.2 to 1.4 times) and higher levels of type II collagen and aggrecan mRNA expression when compared to controls.

New potential therapeutic approach for the treatment of B-Cell malignancies using chlorambucil/hydroxychloroquine-loaded anti-CD20 nanoparticles.

Current B-cell disorder treatments take advantage of dose-intensive chemotherapy regimens and immunotherapy via use of monoclonal antibodies. Unfortunately, they may lead to insufficient tumor distribution of therapeutic agents, and often cause adverse effects on patients. In this contribution, we propose a novel therapeutic approach in which relatively high doses of Hydroxychloroquine and Chlorambucil were loaded into biodegradable nanoparticles coated with an anti-CD20 antibody. We demonstrate their ability to effectively target and internalize in tumor B-cells. Moreover, these nanoparticles were able to kill not only p53 mutated/deleted lymphoma cell lines expressing a low amount of CD20, but also circulating primary cells purified from chronic lymphocitic leukemia patients. Their safety was demonstrated in healthy mice, and their therapeutic effects in a new model of Burkitt's lymphoma. The latter serves as a prototype of an aggressive lympho-proliferative disease. In vitro and in vivo data showed the ability of anti-CD20 nanoparticles loaded with Hydroxychloroquine and Chlorambucil to increase tumor cell killing in comparison to free cytotoxic agents or Rituximab. These results shed light on the potential of anti-CD20 nanoparticles carrying Hydroxychloroquine and Chlorambucil for controlling a disseminated model of aggressive lymphoma, and lend credence to the idea of adopting this therapeutic approach for the treatment of B-cell disorders.

Remodeling of chromatin under low intensity diffuse ultrasound.

A variety of mechanotransduction pathways mediate the response of fibroblasts or chondrocytes to ultrasound stimulation. In addition, regulatory pathways that co-ordinate stimulus-specific cellular responses are likely to exist. In this study, analysis was confined to the hypothesis that ultrasound stimulation (US) influences the chromatin structure, and that these changes may reflect a regulatory pathway that connects nuclear architecture, chromatin structure and gene expression. Murine fibroblasts seeded on tissue culture plates were stimulated with US (5.0 MHz (14 kPa), 51-s per application) and the thermal denaturation profiles of nuclei isolated from fibroblasts were assessed by dynamic scanning calorimetry (DSC). When compared to the thermal profiles obtained from the nuclei of non-stimulated cells, the nuclei obtained from stimulated cells showed a change in peak profiles and peak areas, which is indicative of chromatin remodeling. Independently, US was also observed to impact the histone (H1):chromatin association as measured indirectly by DAPI staining. Based on our work, it appears plausible that US can produce a remodeling of chromatin, thus triggering signal cascade and other intracellular mechanisms.

The effect of ultrasound stimulation on the gene and protein expression of chondrocytes seeded in chitosan scaffolds.

Both pulsed- and square-wave, low-intensity ultrasound (US) signals have been reported to impact chondrocyte function and biosynthetic activity. In this study, a low-intensity diffuse ultrasound (LIDUS) signal at 5.0 MHz (0.14 mW/cm(2)) was employed to stimulate bovine chondrocytes seeded in three-dimensional (3D) chitosan-based matrices. While the duration of application was constant at 51 s, US was applied once, twice, four times and eight times/day, and the impacts of US on the biosynthetic activity of chondrocytes and the expression of chondrocyte-specific genes were evaluated. When stimulated with continuous US for predetermined time intervals, chondrocytes had higher levels of type II collagen, aggrecan, L-Sox5 and Sox9 mRNA expression when compared to controls; however, under the same conditions, the expression of MMP-3 was downregulated. Interestingly, both Sox5 and Sox9 genes coordinately responded to changes in US stimulation and generally mirrored the response of collagen type II transcript to changes in US stimulation. RT-PCR analysis revealed that US stimulation increased the gene expression of cell-surface integrins α5 and ß1. The expression of integrins α2 was downregulated by US treatment, suggesting that multiple integrin subunits may be involved in the regulation of chondrocytic function in response to US stimuli. The enhancement in the abundance of the mRNA transcripts upon US stimulation was observed to correlate with the protein expression of collagen type I, collagen type II, and integrins α5 and ß1. In conclusion, the US stimulation regimen employed was shown to modulate the proliferative capacity, biosynthetic activity and integrin mRNA expression of articular chondrocytes maintained in 3D matrices.

Electrospun cross-linked gelatin fibers with controlled diameter: the effect of matrix stiffness on proliferative and biosynthetic activity of chondrocytes cultured in vitro.

Nanofibrous scaffolds were prepared from gelatin solutions and were further cross-linked with glutaraldehyde (GA). The fiber diameter was varied from 100 to 1000 nm by controlling the applied voltage (4-15 kV) and the concentration of the gelatin solution (4-15%). The tensile moduli and the tensile strength of the noncross-linked scaffolds varied from 20 to 120 MPa and 0.5 to 3.5 MPa, respectively. Cross-linking with GA led to an increase in both the tensile modulus and strength and correlated with cross-linker concentration. Gelatin-based matrices were characterized by Fourier transform infrared spectroscopy and differential scanning calorimetry. High cellular viabilities and rounded morphology of chondrocytes was observed at the end of 7 days in culture with added matrix deposition and flattening of cells at 15 days. Matrix stiffness was noted to impact cell densities and the expression of chondrocytic markers, especially aggrecan. The ratios of collagen-II (C-II) to collagen-I (C-I) of 0.62 and 1.33 were noted on gelatin nanofibrous scaffolds cross-linked with 0.1% GA at the end of 7 and 15 days in culture, respectively. C-II/C-I ratios of 1.30 and 2.58 were noted on scaffolds cross-linked with 1.0% GA at the end of 7 and 15 days in culture, respectively.

Efectividad de la funcionalidad familiar con padre adolescente en San Gil: funcionalidad familiar con padre adolescente / The effectiveness in the functionality of families with teenaged fathers of San Gil

Introducción: El aumento de gestantes adolescentes llevó a estudiar como complemento a la familia del padre adolescente, con la pregunta ¿Cuál es la efectividad de la funcionalidad familiar con adolescentes padres? A fin de determinar la efectividad de su funcionalidad. Metodología: Fue un estudio descriptivo transversal de 90 familias con adolescentes padres, al adolescente se le aplicó la ficha sociodemográfica y el instrumento Efectividad de la Funcionalidad Familiar (Friedemann). Resultados: Los padres adolescentes (41,1%) educación secundaria y trabajan (67,8%). En cuanto a la familia de convivencia: (45,6%) familia nuclear, (56,7%) unión libre, (57,8%) con 4 y 6 personas, y el ingreso económico mensual fue de 1 salario mínimo (63,3%). Se presentó baja efectividad de la funcionalidad familiar (64,4%), nivel intermedio (33,3%) y solo (2,2%) con nivel alto. Conclusiones: Se concluyó que (64,4%) son familias con dificultades en la organización y el crecimiento familiar.

Introduction: The increase of the teenaged pregnant woman led us to study as a complement the families of the teenaged father presenting the following question: What is the effectiveness of the family’s functionality as far as teenaged fathers are concerned in order to determine the effectiveness of their functionality. Methodology:It was a transversal descriptive study done with 90 families of teenaged fathers in which the socio-demographic index was applied as well as the instrument known as The Effectiveness of the Family’s Functionality (Friedemann). Results: The teenaged fathers (41.1%) from secondary education institutions work (67.8%). As far as the couples living together apply: 45.6% nuclear family, and (56.7%) in situations known as “free union”; in the groups of 4 and 6 people (57.8%) and in the groups of a monthly economic income of a minimum salary (63.3%) and only a 2.2% applied to a high level. Conclusion: We arrived to the conclusion that 64.4% are families with difficulties in the family organization and growth.