Calcitonin as a pharmacological anchorage in orthodontics

Objective

This study aimed to evaluate the effects of salmon calcitonin administration as a pharmacological anchoring agent in orthodontics and to determine the influence of locally applied calcitonin on serum calcium levels. The secondary aim was to observe the response of dental and periodontal tissues using light microscopy.

Methods

Fourteen healthy male adult Wistar rats with an average weight of 250 g had their teeth moved, seven of which received a local injection of salmon calcitonin in the furcation region of the left upper first molar. Concurrently, the remaining seven were used as controls. In the control group, saline solution was injected in the bifurcation region of tooth 26 to subject these animals to the same stress level as those of the experimental group. After 14 days, a 6 mm diameter orthodontic elastic band was inserted between teeth 26 and 27 in all animals to induce the movement of these teeth. The rats were anaesthetised and exsanguinated on day 21. In both groups, tooth movement and serum calcium levels were measured. The jaws were dissected with straight scissors, and tissue blocks containing gingiva, bone and teeth were identified, fixed and demineralised. Then, the pieces were cut into semi-serial slices, stained with hematoxylin, eosin, and Mallory's trichrome, and analysed under an Axiophot light microscope.

Results

There was significantly less tooth movement in the experimental group (X̄; 0,150 mm ± 0,037) than in the control group (0,236 mm ± 0,044; P = 0,003), while there was no significant difference in serum calcium levels between the two groups (controlX̄; 9,53 mg/dl ± 1,53; experimental 10,81 mg/dl ± 1,47; P = 0,15).

Conclusion

While calcitonin did not completely inhibit osteoclast activity, it promoted orthodontic anchorage, apparently, by local action.

Colorimetric Detection of SARS-CoV-2 Using Plasmonic Biosensors and Smartphones

Low-cost, instrument-free colorimetric tests were developed to detect SARS-CoV-2 using plasmonic biosensors with Au nanoparticles functionalized with polyclonal antibodies (f-AuNPs). Intense color changes were noted with the naked eye owing to plasmon coupling when f-AuNPs form clusters on the virus, with high sensitivity and a detection limit of 0.28 PFU mL-1 (PFU stands for plaque-forming units) in human saliva. Plasmon coupling was corroborated with computer simulations using the finite-difference time-domain (FDTD) method. The strategies based on preparing plasmonic biosensors with f-AuNPs are robust to permit SARS-CoV-2 detection via dynamic light scattering and UV-vis spectroscopy without interference from other viruses, such as influenza and dengue viruses. The diagnosis was made with a smartphone app after processing the images collected from the smartphone camera, measuring the concentration of SARS-CoV-2. Both image processing and machine learning algorithms were found to provide COVID-19 diagnosis with 100% accuracy for saliva samples. In subsidiary experiments, we observed that the biosensor could be used to detect the virus in river waters without pretreatment. With fast responses and requiring small sample amounts (only 20 μL), these colorimetric tests can be deployed in any location within the point-of-care diagnosis paradigm for epidemiological control.

Evaluation of Biocompatibility, Anti-Inflammatory, and Antinociceptive Activities of Pequi Oil-Based Nanoemulsions in In Vitro and In Vivo Models

Pequi oil (Caryocar brasiliense) contains bioactive compounds capable of modulating the inflammatory process; however, its hydrophobic characteristic limits its therapeutic use. The encapsulation of pequi oil in nanoemulsions can improve its biodistribution and promote its immunomodulatory effects. Thus, the objective of the present study was to formulate pequi oil-based nanoemulsions (PeNE) to evaluate their biocompatibility, anti-inflammatory, and antinociceptive effects in in vitro (macrophages—J774.16) and in vivo (Rattus novergicus) models. PeNE were biocompatible, showed no cytotoxic and genotoxic effects and no changes in body weight, biochemistry, or histology of treated animals at all concentrations tested (90−360 µg/mL for 24 h, in vitro; 100−400 mg/kg p.o. 15 days, in vivo). It was possible to observe antinociceptive effects in a dose-dependent manner in the animals treated with PeNE, with a reduction of 27 and 40% in the doses of 100 and 400 mg/kg of PeNE, respectively (p < 0.05); however, the treatment with PeNE did not induce edema reduction in animals with carrageenan-induced edema. Thus, the promising results of this study point to the use of free and nanostructured pequi oil as a possible future approach to a preventive/therapeutic complementary treatment alongside existing conventional therapies for analgesia.

In Vivo Evaluation of DMSA-Coated Magnetic Nanoparticle Toxicity and Biodistribution in Rats: A Long-Term Follow-Up

This work presents a long-term follow-up (300 days) of rats after a single intravenous injection of DMSA-coated magnetite nanoparticles (DMSA-MNP). The animals were systematically evaluated by hematological, biochemical, and ultrasound examinations, monitoring the same animal over time. In addition, oxidative stress evaluation, DMSA-MNP biodistribution, computerized tomography for ex vivo organs, and histopathology analysis were performed at the end of the experiment period. Overall, DMSA-MNP administration did not cause serious damage to the rats' health over the course of 300 days post-administration. All animals presented hematological parameters within the normal limits, and no alterations on serum creatinine, urea, ALT, and AST were related to DMSA-MNP administration. Liver and spleen showed no important alterations in any of the examinations. The kidneys of treated animals displayed intermittent pelvis dilation at ultrasound analysis, but without damage to the organ parenchyma after 300 days. The lungs of treated animals presented a light interalveolar septal thickening, but the animals did not present any clinical respiratory symptom. Nanoparticles were not detected in the vital organs of treated animals 300 days after administration. This work represents the first assessment of the long-term effects of DMSA-MNP and goes a step further on the safety of its use for biomedical applications.

Influence of particle size on the SARS-CoV-2 spike protein detection using IgG-capped gold nanoparticles and dynamic light scattering

Due to the unprecedented and ongoing nature of the coronavirus outbreak, the development of rapid immunoassays to detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its highly contagious variants is an important and challenging task. Here, we report the development of polyclonal antibody-functionalized spherical gold nanoparticle biosensors as well as the influence of the nanoparticle sizes on the immunoassay response to detect the SARS-CoV-2 spike protein by dynamic light scattering. By monitoring the increment in the hydrodynamic diameter (ΔD_H) by dynamic light scattering measurements in the antigen-antibody interaction, SARS-CoV-2 S-protein can be detected in only 5 min. The larger the nanoparticles, the larger ΔD_H in the presence of spike protein. From adsorption isotherm, the calculated binding constant (K _D ) was 83 nM and the estimated limit of detection was 13 ng/mL (30 pM). The biosensor was stable up to 90 days at 4 °C. Therefore, the biosensor developed in this work could be potentially applied as a fast and sensible immunoassay to detect SARS-CoV-2 infection in patient samples.

Pequi oil (Caryocar brasilense Cambess.) nanoemulsion alters cell proliferation and damages key organelles in triple-negative breast cancer cells in vitro

Pequi oil is extracted from the fruit of a Brazilian native plant (Caryocar brasiliense Camb) that contains some molecules with anticancer potential. Due to its hydrophobic property, the administration of pequi oil associated with nanoemulsion systems represents a successful strategy to improve oil bioavailability. Breast cancer is the most frequent type of cancer among women and conventional therapies used are frequently associated with several side effects. Thus, the aim of this study was to investigate the effects of pequi oil-based nanoemulsion (PeNE) on triple-negative breast cancer cells (4T1), in vitro. PeNE presented a dose- and time-dependent cytotoxic effect with lower IC50 than free pequi oil after 48 h of exposure (p < 0.001). At 180 µg/mL, PeNE demonstrated numerous cell alterations, when compared to free pequi oil, such as morphological alterations, reduction in cell proliferation and total cell number, damage to plasmatic membrane, induction of lysosomal membrane permeability and depolarization of mitochondrial membrane, alteration of intracellular ROS production and calcium level, and increase in phosphatidylserine exposure. Taken together, the results suggest an interesting induction of cell death mechanisms involving a combined action of factors that impair nucleus, mitochondria, lysosome, and ER function. In addition, more pronounced effects were observed in cells treated by PeNE at 180 µg/mL when compared to free pequi oil, thereby reinforcing the advantages of using nanometric platforms. These promising results highlight the use of PeNE as a potential complementary therapeutic approach to be employed along with conventional treatments against breast cancer in the future.

Cardiovascular risk profile of a young adult population with high risk for obstructive sleep apnea screened by Stop-Bang and Epworth sleepiness scale in a primary health care unit

Objective

To establish the relationship between cardiovascular (CV) risk profile and detected risk of Obstructive Sleep Apnea (OSA) in two questionnaires - STOP-BANG (SB) and Epworth Sleepiness Scale (ESS), in a young population of adults registered in a Primary Health Care unit in Brazil.

Design and methods

This cross-sectional population study enrolled adults between 20–50 years old, registered in a primary healthcare unit in Brazil. A database is being developed including sociodemographic and anthropometric data, and CV risk factors. Office blood pressure (BP) and Home Blood Pressure Monitoring (HBPM) (7-day protocol) (Omron-705CP). Moreover, OSA was investigated by SB and ESS. Patients with a high risk for OSA in either of these two questionnaires were subsequently assigned for polysomnography (PSG).

Results

A total of 562 subjects were evaluated [40% males, 38.9±8.8 years], where 151 (26.9%) were identified as high risk for OSA by the SB questionnaire and 210 (37.4%) by ESS. The most common CV risk factor was physical inactivity (43%), followed by dyslipidemia (38%) and obesity (28%). By OBP, the prevalence of hypertension was 13.4% while by HBPM was 18.6%, with a low concordance between them (kappa=0.472). Subjects with a high risk at SB are older, with a higher prevalence of obesity, hypertension and higher office BP and HBPM. On the other hand, individuals with high-risk by ESS were more obese, with increased waist circumference, higher prevalence of dyslipidemia and metabolic syndrome. Nevertheless, there was no difference in BP levels. Among the subjects submitted to PSG, 46% had a diagnosis of OSA (AHI ≥5/hour) and 23% of moderate/severe OSA (AHI&gt;15/hour). The best predictor of AOS was SB, positive in 100% of subjects with moderate/severe OSA, while ESS was positive in only 20% of them.

Conclusion

This young and apparently healthy population presented a high prevalence and risk for OSA. The SB had a higher association with higher BP levels, while ESE was associated with a worse metabolic profile. SB questionnaire seems to be the best predictor for moderate/severe OSA in this young adult population.

Funding Acknowledgement

Type of funding sources: None.

The induction of immunogenic cell death by photodynamic therapy in B16F10 cells in vitro is effected by the concentration of the photosensitizer

Photodynamic therapy (PDT) can trigger immune responses against cancer cells. The induction of immunogenic cell death (ICD) is one of the possible mechanisms behind this event, but the protocol conditions necessary for a robust induction of ICD by PDT have not been defined. In this work, the immunogenicity of B16F10 melanoma cells treated with different PDT protocols was investigated. The exposure of damage-associated molecules (DAMPs), namely HMGB1, calreticulin and ATP, a hallmark of ICD, and the presence of apoptotic and necrotic cells were assessed after the application of PDT mediated by different concentrations of aluminum-phthalocyanine (AlPcNE) in vitro. Furthermore, the in vivo immunogenicity of PDT-treated B16F10 cells was investigated with an immunization-challenge model in C57BL/6 mice. The percentage of dead cells was directly proportional to the concentration of AlPcNE. The IC₅₀, IC₇₀ and IC₉₀ concentrations of AlPcNE induced the exposure of DAMPs by B16F10 cells after PDT. In the in vivo model, however, only the B16F10 cells treated with PDT-AlPcNE at the IC₅₀ or IC₇₀ rendered C57BL/6 significantly more resistant to a subsequent challenge with viable B16F10 cells. Thus, the induction of ICD in B16F10 cells by PDT occurs only at a specific range of AlPcNE concentrations.

Oral delivery of fish oil in oil-in-water nanoemulsion: development, colloidal stability and modulatory effect on in vivo inflammatory induction in mice

To improve the oral absorption of fish oil and test its anti-inflammatory effect, a fish oil nanoemulsion was developed using cis-4,7,10,13,16,19-docosahexaenoic fatty acid as a biomarker for oral administration. The colloidal stability tests of the fish oil nanoemulsion showed an average size of 155.44 nm ± 6.46 (4 °C); 163.04 nm ± 9.97 (25 °C) and polydispersity index 0.22 ± 0.02 (4 °C), 0.21 ± 0.02 (25 °C), indicating systems with low polydispersity and stable droplets. The fish oil nanoemulsion did not alter the cell viability of the RAW 264.7 macrophages and, at a concentration of 0.024 mg/mL, was kinetically incorporated into the cells after 18 h of contact. The nanoemulsion was maintained in the gastrointestinal region for a significantly shorter period of time (p ≤ 0.05) compared to the intake of fish oil in free form. Inflammatory tests demonstrated that nanoemulsion and fish oil showed less (p ≤ 0.05) neutrophil infiltration after 24h of sepsis induction and there was a significant reduction (p ≤ 0.05) in the volume of paw edema in female adult Balb/c mice who received the nanoemulsion diet compared to the other experimental groups (control, formalin, fish oil and sunflower oil). These results indicate that the fish oil nanoemulsion was significantly effective in the dietary conditions tested here, presenting satisfactory responses in the modulation of inflammatory disorders, demonstrating interesting and beneficial nutraceutical effects.

HBPM to refine the diagnosis of hypertension in a Family Health Care Unit in RJ, Brazil - LapARC

Background

The new hypertension (HT) guidelines recommend the use of out-of-office blood pressure (BP) measures for its diagnosis however, in the scope of public health in Brazil, it is still based on office BP (OBP) for logistical and financial reasons. Furthermore, in our country, it is not yet clear whether the use of out-of-office BP would really be more reliable for the diagnosis.

Objective

To evaluate the importance of using Home Blood Pressure Monitoring (HBPM) in diagnosing HT in a young adult population in primary care in Brazil.

Methods

A cross-sectional population study enrolled adults between 20 and 50 years in a primary healthcare unit in Rio de Janeiro. Office BP was the mean value of 2 measures, while the HBPM followed a 7-day protocol. It was considered normal a Home BP &lt; 135x85 mmHg and OBP &lt;140x90 mmHg. Patients were classified into 4 phenotypes: normotension (controlled OBP and HBPM); white coat HT (uncontrolled OBP and controlled HBPM); masked HT (controlled OBP and uncontrolled HBPM) and sustained HT (uncontrolled OBP and HBPM).

Results

A total of 462 individuals were enrolled [38% males; mean age 36±9 years]. Sedentary lifestyle (43%), dyslipidemia (38%) and obesity (28%) were the main CV risk factors. OBP, the prevalence of HT was 13%, HBPM it was 19%, with low concordance between them (kappa=0.472). After HBPM, 17% changed the diagnosis, being 6% of them white-coat HT and 11% masked HT. The variables that were independently associated with HT diagnosed by OBP were male gender (OR 1.83,CI95%:1.01-3.33,p=0.04) and increased neck circumference (OR 3.77,CI95%:1.59-8.93,p=0.003), whilst by HBPM they were obesity (OR 2.18,CI95%:1.27-3.76,p=0.005) and increased neck circumference (OR 2.37,CI95%:1.05-5.33,p=0.04).

Conclusions

If the diagnosis was based only in the office BP values, 17% of the subjects would've had an erroneous diagnosis of hypertension, suggesting the importance of implementing out-of-office BP measurements in primary care.

Key messages

Home monitoring blood pressure corrected the diagnosis of hypertension of 17% of patients, allocating them correctly into white-coat HT and masked HT. Increased neck circumference was independently associated with the diagnosis of hypertension by both methods.

Synergistic Antitumor Efficacy of Magnetohyperthermia and Poly(lactic-co-glycolic acid)-Encapsulated Selol in Ehrlich Breast Adenocarcinoma Treatment in Elderly Swiss Mice

Nanobiotechnology strategies for cancer treatments are currently being tested with increasing interest, except in elderly groups. It is well established that breast cancer incidence increases with age and that traditional therapies usually generate severe adverse effects, especially for elderly groups. To investigate if the benefits of nanotechnology could be extended to treating cancer in this group, citrate-coated maghemite nanoparticles (NpCit) were used for magnetohyperthermia (MHT) in combination with the administration of PLGA-Selol nanocapsule (NcSel), a formulation with antioxidant and antitumor activity. The combined therapies significantly inhibited breast Ehrlich tumor growth and prevented metastases to the lymph nodes, liver and lungs until 45 days after tumor induction, a better result than the group undergoing conventional drug treatment. The levels of TNF-α, associated with poor prognosis in Ehrlich tumor, were also normalized. Therefore, the results evidenced the potential use of these therapies for future clinical trials in elderly breast cancer patients.

Phonophoretic application of a glucosamine and chondroitin nanoemulsion for treatment of knee chondropathies

Aim: This study was performed to assess the effect of the phonophoretic application of a nanoemulsion incorporating glucosamine and chondroitin sulfate (NANO-CG) associated with kinesiotherapy on the reduction of pain and stiffness in knee chondropathy. Materials & methods: NANO-CG was tested in vitro and in vivo prior to being applied in a randomized and controlled clinical trial. Results: Cell viability and hen's egg test-chorionallantonic membrane tests indicated the NANO-CG is safe for topical application. Permeation tests showed NANO-CG enhances drug permeation through the skin. There was no statistical significance between treated groups in this preliminary study, however, pain reduction and complete recovery of articular cartilage were observed in some patients treated with NANO-CG. Conclusion: We demonstrate that NANO-CG may be a promising candidate for the therapy of knee chondropathy.

Exposure to Maghemite Nanoparticles Induces Epigenetic Alterations in Human Submandibular Gland Cells

Even though nanotechnology has revolutionized the biomedical research, a plethora of studies debate the nanoparticles safety. In order to contribute to these studies, we evaluated the cytotoxic and epigenetic effects of maghemite nanoparticles covered with citric acid on human submandibular gland cells. Objective: This work objective was to evaluate the cytotoxic effects and epigenetic alterations induced in human salivary gland cells after treatment with maghemite nanoparticles covered with citric acid. Methods: For that, human submandibular gland cells were cultured and treated with nanoparticles for 24 or 48 hours. To assess cytotoxicity we used lactate dehydrogenase, a general oxidative stress indicator assay and microscopy. Epigenetic status was detected by colorimetric assays and the results were confirmed by quantitative polymerase chain reaction. Results: No cytotoxic effects were detected on cells exposed to up 3.0 mgFemL^-1 for 48 hours, although cytoplasmic vacuoles formation was detected by light microscopy analyses. An increased generation of reactive oxygen species in cells exposed to nanoparticles was evidenced and iron clusters accumulated in the cytoplasm of treated cells. Global DNA methylation and histones H3 and H4 acetylation were also altered in response to nanoparticles exposure, thus suggesting a reprogramming of the epigenome. Transcripts accumulation analyses showed that genes related to iron metabolism and oxidative stress were upregulated, while the gene related to epigenetic reprogramming presented reduced transcript accumulation after treatment. Conclusion: We concluded that maghemite nanoparticles covered with citric acid exposure provoked several biological responses without impairment of human submandibular gland cells viability. This is the first report on the epigenetic effects of maghemite nanoparticles on this cell lineage.

Photodynamic therapy for cutaneous hemangiosarcoma in dogs

Cutaneous hemangiosarcoma is a malignant neoplasia that frequently occurs in dogs. The most effective treatment requires wide surgical excision of the tumor. To avoid mutilating surgeries, photodynamic therapy (PDT) could serve as an alternative treatment. This study aimed to treat cutaneous hemangiosarcomas in dogs using PDT with aluminium-chloride-phthalocyanine nanoemulsion (AlClPc-nano) as photosensitizer. Eight dogs with histopathological diagnosis of naturally occurring cutaneous hemangiosarcoma were treated. Animals were given intra and peritumoral injections of AlClPc-nano (13.3 μM). After 15 min, the masses were LED irradiated at a wavelength of 658-662 nm (80 mW potency) for 25 min (120 J/cm² fluency). The number of sessions was based on lesion observations, with PDT sessions repeated every 7 days until the mass was no longer macroscopically visible. On that occasion, an excisional biopsy of the area was taken for histopathology analysis. Blood was collected from each animal before each PDT session and excisional biopsy for hematological analysis (blood counts; liver and kidney function). The number of PDT sessions varied from 2 to 4, depending on the size of the initial mass. Seven of the eight cases demonstrated complete remission of neoplasia. Microscopic analysis of the excisional biopsies showed necrosis and hemorrhage only, with no cancer cells, except in one case. During the treatment, inflammation and necrosis were macroscopically observed in the treated areas. The dogs did not show any alteration in blood parameters that could be related to the PDT. In conclusion, PDT with AlClPc-nano is a safe and effective treatment for cutaneous hemangiosarcoma in dogs.

The influence of female mice age on biodistribution and biocompatibility of citrate-coated magnetic nanoparticles

BACKGROUND

Magnetic nanoparticles (MNPs) have been successfully tested for several purposes in medical applications. However, knowledge concerning the effects of nanostructures on elderly organisms is remarkably scarce.

PURPOSE

To fill part of this gap, this work aimed to investigate biocompatibility and bio-distribution aspects of magnetic nanoparticles coated with citrate (NpCit) in both elderly and young healthy mice.

METHODS

NpCit (2.4 mg iron) was administered intraperitoneally, and its toxicity was evaluated for 28 days through clinical, biochemical, hematological, and histopathological examinations. In addition, its biodistribution was evaluated by spectrometric (inductively coupled plasma optical emission spectrometry) and histological methods.

RESULTS

NpCit presented age-dependent effects, inducing very slight and temporary biochemical and hematological changes in young animals. These changes were even weaker than the effects of the aging process, especially those related to the hematological data, tumor necrosis factor alpha, and nitric oxide levels. On the other hand, NpCit showed a distinct set of results in the elderly group, sometimes reinforcing (decrease of lymphocytes and increase of monocytes) and sometimes opposing (erythrocyte parameters and cytokine levels) the aging changes. Leukocyte changes were still observed on the 28th day after treatment in the elderly group. Slight evidence of a decrease in liver and immune functions was detected in elderly mice treated or not treated with NpCit. It was noted that tissue damage or clinical changes related to aging or to the NpCit treatment were not observed. As detected for aging, the pattern of iron biodistribution was significantly different after NpCit administration: extra iron was detected until the 28th day, but in different organs of elderly (liver and kidneys) and young (spleen, liver, and lungs) mice.

CONCLUSION

Taken together, the data show NpCit to be a stable and reasonably biocompatible sample, especially for young mice, and thus appropriate for biomedical applications. The data showed important differences after NpCit treatment related to the animals' age, and this emphasizes the need for further studies in older animals to appropriately extend the benefits of nanotechnology to the elderly population.

UHPLC-MS and MALDI-MS study of aluminum phthalocyanine chloride and development of a bioanalytical method for its quantification in nanoemulsions and biological matrices

Metal phthalocyanines are promising components in photodynamic therapy. Aluminum phthalocyanine chloride (AlClPc) has been used to treat oral cancer in mice, human carious tissue, lung cancer cells and other conditions. To overcome the high hydrophobicity of AlClPc, phthalocyanine is often encapsulated in nanoformulations. Despite increased usage, little is known about the pharmacokinetics and biodistribution of AlClPc. The aim of this study was the development and validation of a UHPLC-MS method for the determination of AlClPc in solution after extraction from nanoformulations and biological matrices such as plasma and tissue. The described method has been assayed as to selectivity, linearity, limits of detection and quantification, precision and recovery. The present study is the first to describe the behavior of AlClPc in biological matrices with mass spectrometry as well as the first to describe the chromatographic behavior of AlClPc contaminants. Molecular mass analysis identified dechlorination of AlClPc by both LC/MS and MALDI-MS and an adduct formation in LC/MS. The parameters observed indicated that the method has applicability and robustness for use in biodistribution studies.

DNA methylation alterations induced by transient exposure of MCF-7 cells to maghemite nanoparticles

AIM

To evaluate the DNA methylation profile of MCF-7 cells during and after the treatment with maghemite nanoparticles (MNP-CIT).

MATERIALS & METHODS

Noncytotoxic MNP-CIT concentrations and cell morphology were evaluated by standard methods. DNA methylation was assessed by whole genome bisulfite sequencing. DNA methyltransferase (DNMT) genes expression was analyzed by qRT-PCR.

RESULTS

A total of 30 and 60 µgFeml^-1 MNP-CIT accumulated in cytoplasm but did not present cytotoxic effects. The overall percentage of DNA methylation was not affected, but 58 gene-associated regions underwent DNA methylation reprogramming, including genes related to cancer onset. DNMT transcript levels were also modulated.

CONCLUSION

Transient exposure to MNP-CIT promoted epigenomic changes and altered the DNMT genes regulation in MCF-7 cells. These events should be considered for biomedical applications.

Integrated assessment of toxic effects of maghemite (γ-Fe2O3) nanoparticles in zebrafish

The increasing use of nanotechnology in the last decade has raised concerns about the impact of nanoparticles in the environment. In particular, the potential harmful effects of iron oxide nanoparticles (IONPs) in aquatic organisms have been poorly addressed. We analyze here the toxic effects induced by IONPs in zebrafish using a combination of classical (genotoxicity, oxidative stress) and molecular (transcriptomic) methodologies. Adult animals were exposed for 96h to five sub-lethal IONP concentrations, ranging from 4.7 to 74.4mg/L. Comet and micronucleus assays revealed a significant number of DNA lesions induced by IONPs at all concentrations tested. Conversely, the thiobarbituric acid reactive substances (TBARS) test detected only a mild oxidative damage in liver cells (∼1.5-fold increase of malondialdehyde concentrations) and only at the two higher IONP concentrations tested. Microarray analysis of liver samples identified 953 transcripts (927 unique genes) differentially expressed between controls and IONP-exposed samples. Subsequent functional analysis identified genes related to cation/metal ion binding, membrane formation, and morphogenesis among the transcripts overrepresented upon IONP treatments, whereas mRNAs encompassing genes associated with RNA biogenesis, translation, ribosomes, and several metabolic processes became underrepresented in treated samples. Taken together, these results indicate considerable genotoxic effects of IONPs combined with general negative effect on cell growth and on the ability of the cell produce new proteins. On the contrary, IONPs showed only a limited capacity to induce oxidative stress. To our knowledge, this is the first study on IONPs toxicity using such an integrative approach in an aquatic organism.

Distraction Osteogenesis May Promote Periodontal Bone Regeneration

Distraction osteogenesis has numerous applications in the treatment of conditions affecting the dentofacial complex, from midface advancement to orthodontic tooth movement produced by transversal distraction of the periodontal ligament. The purpose of this study was to test the hypothesis that periodontium can be consistently distracted toward the tooth crown to promote periodontal bone regeneration. After the surgical production of periodontal defects in maxillary canines of 5 mongrel dogs, periodontal bone distraction was performed. Light microscopy was used for histopathological and morphometric analysis. Periodontal bone regeneration occurred in all animals. Periodontal bone regeneration in the distraction sites (Mean ± SD: 5.45 ± 2.01 mm) differed from that in control sites (0.008 ± 0.67 mm; p < 0.0001). Periodontal bone distraction resulted in periodontal bone regeneration. This finding may establish periodontal bone distraction as a new treatment alternative for periodontal defects.

Effects of γ-Fe2O3 nanoparticles on the survival and reproduction of Biomphalaria glabrata (Say, 1818) and their elimination from this benthic aquatic snail

This study aims to evaluate the effects of maghemite nanoparticles (γ-Fe2O3) coated with meso-2, 3-dimercaptosuccinic acid (DMSA) stabilizer on the survival and reproduction of the aquatic snail Biomphalaria glabrata. The cumulative means of egg masses and eggs per individual in the control group at the end of 4 weeks were 18.8 and 326.7, respectively. These values at the concentration of 1 mg/L were 17.2 and 291.6; at 10 mg/L, they were 19.6 and 334.4 ,and at 100 mg/L, they were 14.3 and 311.1. Results showed no significant differences between the tested and the control groups at the level of p < 0.05. Exposure of embryos for 10 days showed absence of mortality, malformation, or hatching delay. X-ray microtomography confirmed the presence of nanoparticles in exposed individuals and showed the complete elimination of the nanoparticles after 30 days in clean water. In the studied conditions, it is clear that γ-Fe2O3 coated with stabilizing DMSA did not alter the fecundity or the fertility of the snail B. glabrata after 4 weeks of exposure, and accumulation was not present after 30 days in clean water.

A reduction in CD90 (THY-1) expression results in increased differentiation of mesenchymal stromal cells

BACKGROUND

Mesenchymal stromal cells (MSCs) are multipotent progenitor cells used in several cell therapies. MSCs are characterized by the expression of CD73, CD90, and CD105 cell markers, and the absence of CD34, CD45, CD11a, CD19, and HLA-DR cell markers. CD90 is a glycoprotein present in the MSC membranes and also in adult cells and cancer stem cells. The role of CD90 in MSCs remains unknown. Here, we sought to analyse the role that CD90 plays in the characteristic properties of in vitro expanded human MSCs.

METHODS

We investigated the function of CD90 with regard to morphology, proliferation rate, suppression of T-cell proliferation, and osteogenic/adipogenic differentiation of MSCs by reducing the expression of this marker using CD90-target small hairpin RNA lentiviral vectors.

RESULTS

The present study shows that a reduction in CD90 expression enhances the osteogenic and adipogenic differentiation of MSCs in vitro and, unexpectedly, causes a decrease in CD44 and CD166 expression.

CONCLUSION

Our study suggests that CD90 controls the differentiation of MSCs by acting as an obstacle in the pathway of differentiation commitment. This may be overcome in the presence of the correct differentiation stimuli, supporting the idea that CD90 level manipulation may lead to more efficient differentiation rates in vitro.

Labeling mesenchymal cells with DMSA-coated gold and iron oxide nanoparticles: assessment of biocompatibility and potential applications

BACKGROUND

Nanoparticles' unique features have been highly explored in cellular therapies. However, nanoparticles can be cytotoxic. The cytotoxicity can be overcome by coating the nanoparticles with an appropriated surface modification. Nanoparticle coating influences biocompatibility between nanoparticles and cells and may affect some cell properties. Here, we evaluated the biocompatibility of gold and maghemite nanoparticles functionalized with 2,3-dimercaptosuccinic acid (DMSA), Au-DMSA and γ-Fe2O3-DMSA respectively, with human mesenchymal stem cells. Also, we tested these nanoparticles as tracers for mesenchymal stem cells in vivo tracking by computed tomography and as agents for mesenchymal stem cells magnetic targeting.

RESULTS

Significant cell death was not observed in MTT, Trypan Blue and light microscopy analyses. However, ultra-structural alterations as swollen and degenerated mitochondria, high amounts of myelin figures and structures similar to apoptotic bodies were detected in some mesenchymal stem cells. Au-DMSA and γ-Fe2O3-DMSA labeling did not affect mesenchymal stem cells adipogenesis and osteogenesis differentiation, proliferation rates or lymphocyte suppression capability. The uptake measurements indicated that both inorganic nanoparticles were well uptaken by mesenchymal stem cells. However, Au-DMSA could not be detected in microtomograph after being incorporated by mesenchymal stem cells. γ-Fe2O3-DMSA labeled cells were magnetically responsive in vitro and after infused in vivo in an experimental model of lung silicosis.

CONCLUSION

In terms of biocompatibility, the use of γ-Fe2O3-DMSA and Au-DMSA as tracers for mesenchymal stem cells was assured. However, Au-DMSA shown to be not suitable for visualization and tracking of these cells in vivo by standard computed microtomography. Otherwise, γ-Fe2O3-DMSA shows to be a promising agent for mesenchymal stem cells magnetic targeting.

Biotransformation of magnetic nanoparticles as a function of coating in a rat model

Long-term in vivo studies in murine models have shown that DMSA-coated nanoparticles accumulate in spleen, liver and lung tissues during extended periods of time (at least up to 3 months) without any significant signs of toxicity detected. During that time, nanoparticles undergo a process of biotransformation either by reducing the size or the particle aggregation or both. Using a rat model, we have evaluated the transformations of magnetic nanoparticles injected at low doses. Particles with two different coatings, dimercaptosuccinic acid (NP-DMSA) and polyethylene glycol (NP-PEG-(NH2)2) have been administered to animals, to evaluate the role of coating in the degradation of the particles. We have found that low doses of magnetic nanoparticles are quickly metabolized by the animals. In fact, using a nanoparticle dose four times lower than in previous experiments, NP-DMSA were not observed 24 h after the administration either in the liver or in the lungs. Interestingly, an increased amount of ferritin, the iron storage protein, was observed in liver tissues from rats that were treated with the low dose of NP-DMSA in comparison with the control ones, suggesting a rapid metabolization of the particles into ferritin iron. On the other side we have found that, NP-PEG-(NH2)2 are still detectable in several organs 24 h after their administration at low doses. Probably, due to the longer circulation times of the NP-PEG-(NH2)2, there is a delay in the arrival of the particles to the tissue and this is the reason why we are able to see the particles 24 h post-administration. PEG coating could also be protecting the nanoparticles from rapid degradation of the reticuloendothelial system. Knowledge on the biodistribution, circulation time and degradation processes is required to gain a better understanding of the safety evaluation of this kind of nanomaterial for biomedical applications.

Synthesis, characterization and magnetic properties of polymer-Fe3O4 nanocomposite

The chemical stability of magnetic particles is of great importance for their applications in medicine and biotechnology. The most challenging problem in physics of disordered systems of magnetic nanoparticles is the investigation of their dynamic properties. The chemical coprecipitation process was used to synthesize spherical magnetite nanoparticles of 14 nm. The as-prepared magnetite nanoparticles have been aged in the matrix. Magnetic properties and aging effect were studied by Mössbauer spectroscopy at temperatures ranging from 77 to 300 K, and X-ray diffraction. At room temperature, the Mössbauer spectrum showed superparamagnetic behavior of the particles, while well-defined sextets were observed at 77K, indicating a blocked regime. The superparamagnetic magnetite nanoparticles can be used as microbead biosensors.

Photoacoustic spectroscopy study of Blepharocalyx salicifolius (Kunt) O. Berg

Photoacoustic spectroscopy (PAS) has revolutionized the fields of biological, environmental, and agricultural sciences. It is a very simple, sensitive, and non-destructive technique that allows the determination of optical properties of bio-samples. The in vivo chlorophylls of the leaf have a recorded maximum absorption peak at 675 nm as against 665 nm of the in vitro chlorophylls. The intensity of purple pigmentation in leaves of Blepharocalyx salicifolius (Kunt) O. Berg, is inversely correlated to the soil moisture levels, leaf water content and leaf water potentials. The applicability of PAS to biological samples was discussed. It allows the validation of existing emission models which are important for atmospheric process. A portable device for photoacoustic spectroscopy of plants and other photosynthetic tissues, cells and organelles is provided. Further, there is provided a method to measure photosynthesis of such tissues, cells and organelles.

Photoacoustic investigation of maghemite-based nanocomposite

Photoacoustic spectroscopy was used to investigate magnetic nanocomposites incorporating nanosized maghemite particles into styrene-divinylbenzene copolymer template. Typical photoacoustic features were observed in bands C, S and L in the wavelength region of 300-1000 nm. The relative intensity of band-C scaled with the nominal concentration of nanosized maghemite incorporated into the polymeric template whereas the lowest relative intensity of band-S was found in the sample in which the template polymerization took place in the presence of the highest polar-like reaction medium. X-ray diffraction and transmission electron microscopy were used to characterize the magnetic nanosized phase as maghemite, with average particle diameter of 6.9 nm (sample Est34), 7.0 nm (sample H30), and 7.9 nm (sample Em15).

Ex vivo evaluation of caries infiltration after different application times in primary molars

Low viscosity resins (infiltrants) have been shown to penetrate the lesion body of natural caries lesions almost completely in vitro. However, penetration depths (PD) have not been evaluated in vivo. Therefore, the aim of the present study was to evaluate the penetration of an infiltrant into proximal caries lesions in primary molars after different application times using an ex vivo model. 59 proximal lesions from 34 children were randomly allocated to one of the application times and were infiltrated under clinical conditions for 1, 3, or 5 min. After extraction or exfoliation (n = 48), teeth were sectioned perpendicular to their surfaces and lesion depths (LD) as well as lesion areas (LA) were evaluated using polarized light microscopy. PD and penetration areas (PA) were measured on scanning electron microscopic images. Percentage penetration depth (PPD) and percentage penetration area (PPA) were calculated. The mean (±SD) LD and LA were 596 ± 203 µm and 4.03 ± 2.75 × 10(5) µm(2), respectively. PPD ranged from 70 to 80% and PPA from 54 to 60%. Longer application times did not result in significantly deeper or more complete penetration (p > 0.05; ANOVA). In conclusion, proximal caries lesions in primary molars can be infiltrated in vivo to a similar extent as observed previously in vitro. Moreover, 1-min application of the infiltrant led to PD and homogeneity similar to those observed with longer application times up to 5 min.

Anti-CEA loaded maghemite nanoparticles as a theragnostic device for colorectal cancer

Nanosized maghemite particles were synthesized, precoated (with dimercaptosuccinic acid) and surface-functionalized with anticarcinoembryonic antigen (anti-CEA) and successfully used to target cell lines expressing the CEA, characteristic of colorectal cancer (CRC) cells. The as-developed nanosized material device, consisting of surface decorated maghemite nanoparticles suspended as a biocompatible magnetic fluid (MF) sample, labeled MF-anti-CEA, was characterized and tested against two cell lines: a high-CEA expressing cell line (LS174T) and a low-CEA expressing cell line (HCT116). Whereas X-ray diffraction was used to assess the average core size of the as-synthesized maghemite particles (average 8.3 nm in diameter), dynamic light scattering and electrophoretic mobility measurements were used to obtain the average hydrodynamic diameter (550 nm) and the zeta-potential (−38 mV) of the as-prepared and maghemite-based nanosized device, respectively. Additionally, surface-enhanced Raman spectroscopy (SERS) was used to track the surface decoration of the nanosized maghemite particles from the very first precoating up to the attachment of the anti-CEA moiety. The Raman peak at 1655 cm⁻¹, absent in the free anti-CEA spectrum, is the signature of the anti-CEA binding onto the precoated magnetic nanoparticles. Whereas MTT assay was used to confirm the low cell toxicity of the MF-anti-CEA device, ELISA and Prussian blue iron staining tests performed with both cell lines (LS174T and HCT116) confirm that the as-prepared MF-anti- CEA is highly specific for CEA-expressing cells. Finally, transmission electron microscopy analyses show that the association with anti-CEA seems to increase the number of LS174T cells with internalized maghemite nanoparticles, whereas no such increase seems to occur in the HCT116 cell line. In conclusion, the MF-anti-CEA sample is a biocompatible device that can specifically target CEA, suggesting its potential use as a theragnostic tool for CEA-expressing tumors, micrometastasis, and cancer-circulating cells.

Long-term biodistribution and biocompatibility investigation of dextran-coated magnetite nanoparticle using mice as the animal model

Magnetic resonance is used to investigate biodistribution aspects of dextran-coated magnetite nanoparticles (9.4 nm core diameter) in both liver and spleen from 5 minutes up to 6 months after intravenous administration of a magnetic fluid sample in female Swiss mice. Using magnetic resonance data important parameters such as the absorption half-life (t 1/2 = 12 +/- 2 min in the liver and t 1/2 = 11 +/- 2 min in the spleen), the peak time (1.7 +/- 0.2 h in the liver and 1.9 +/- 0.2 h in the spleen), and the disposition half-life of the dextran-coated magnetite nanoparticles in mice organs (t 1/2 = 70 +/- 10 h in the liver and t 1/2 = 32 +/- 7 h in the spleen) were assessed. In addition, light and electron microscopy showed several aspects that may be related to the iron metabolism. Microscopic analysis also revealed that although magnetite nanoparticles or iron released from them are retained in the organism for a long period of time, no morphologic alteration is induced by the intravenous administration of the magnetic fluid sample, evidencing its biocompatibility. The used tests may represent an adequate methodology for nanotoxicology evaluation.

Comparison of stem cell properties of cells isolated from normal and inflamed dental pulps

AIM

To compare cells from normal and inflamed human dental pulps regarding the presence of stem cells, their proliferation and differentiation potential.

METHODOLOGY

Human dental pulp stem cells (hDPSCs) were isolated from normal (DPSC-N) and inflamed dental pulps (DPSC-I). They were compared in respect to proliferation (MTT assay), morphology and STRO-1 expression. STRO-1-positive cells were subject to proliferation (MTT and CFU counting) and morphological analyses and then submitted to odonto-osteogenic, adipogenic and condrogenic differentiation. Differentiated cells were evaluated concerning morphology and the expression, by qRT-PCR, of BSP, LPL and SOX-9 genes. The amount of mineralized matrix produced after odonto-osteogenic differentiation was compared with quantitative Alizarin Red staining.

RESULTS

No difference was observed in the morphology and in the proliferation rate of DPSC-N and DPSC-I either before or after separation of STRO-1-positive cells. These cells represented 0.46% (±0.14) and 0.43% (±0.19) of the cell population from normal and inflamed dental pulps, respectively. Both DPSC-N and DPSC-I were capable of differentiating under the three assayed conditions and presented similar patterns for BSP, LPL and SOX-9 expression. Mineralized matrix production was also compatible. In all the quantitative experiments, differences were found between cells from each patient, either from normal or from inflamed pulps. Nonetheless, there was no statistical difference between these two groups.

CONCLUSION

The morphology, proliferation rate and differentiation potential of DPSC-I were similar to the observed in DPSC-N, thus demonstrating that the inflammatory process did not affect the stem cell properties that were assessed.

New magnetic fluid developed with natural organic compounds biocompatible

This work was developed with an aqueous suspension of maghemite nanoparticles and colloidal emulsions with nanoparticles of magnetite. The nanoparticles were synthesized by co-precipitation method. The first was the magnetic emulsion nanoparticles of maghemite dispersed in the aqueous extract obtained from the leaf embauba (Cecropia Obtusifolia), whose tree is native to Central and South America. Thereby achieving the magnetic fluid extract embauba stabilized with ionic buffer solution pH 7.4. A second emulsion was prepared with colloidal magnetite nanoparticles with surfaces previously coated with oleic acid as a means of dispersing and using the oil extracted from in nature seed Andiroba (Carapa Guianensis), tree of the Brazilian Amazon. These new magnetic fluids the nanoparticles were characterized by Photoacoustic spectroscopy (PAS) to determine the coating layer of molecules on the surfaces of nanoparticles. In aqueous ionic magnetic fluid Cecropia Obtusifolia (MFCO) chlorogenic acid contributes to the electron density in the presence of four groups alcohols, a ketone group and a carboxylic group. In magnetic fluid-based oil andiroba MFAD PAS spectra show that oleic acid molecules are tightly linked on the surface of the nanoparticles.

Liposomal photosensitizers: potential platforms for anticancer photodynamic therapy

Photodynamic therapy is a well-established and clinically approved treatment for several types of cancer. Antineoplastic photodynamic therapy is based on photosensitizers, i.e., drugs that absorb photons translating light energy into a chemical potential that damages tumor tissues. Despite the encouraging clinical results with the approved photosensitizers available today, the prolonged skin phototoxicity, poor selectivity for diseased tissues, hydrophobic nature, and extended retention in the host organism shown by these drugs have stimulated researchers to develop new formulations for photodynamic therapy. In this context, due to their amphiphilic characteristic (compatibility with both hydrophobic and hydrophilic substances), liposomes have proven to be suitable carriers for photosensitizers, improving the photophysical properties of the photosensitizers. Moreover, as nanostructured drug delivery systems, liposomes improve the efficiency and safety of antineoplastic photodynamic therapy, mainly by the classical phenomenon of extended permeation and retention. Therefore, the association of photosensitizers with liposomes has been extensively studied. In this review, both current knowledge and future perspectives on liposomal carriers for antineoplastic photodynamic therapy are critically discussed.

P1-01-02: T Cell Is a Key Player in the Establishment of Cancer Associated Pre-Metastatic Bone Disease

Syngeneic mouse models of malignant diseases have the important advantage of allowing studies to be carried out in immunocompetent animals. In this work, the 4T1(metastatic) and 67NR (non-metastatic) sibling cell lines of mammary mouse carcinomas, syngeneic to BALB/c mouse were used to study tumor specific immune response and its impact on bone disease.

By day 11 after tumor injection, in the absence of metastasis, pro-osteoclastogenic cytokines IL17F, TNFα, IL-1β and RANKL were present in the BM of 4T1+ mice in contrast to the virtual absence of these in the BM of 67NR+ animals.

More important, imaging studies (histomorphometry and microCT) showed that trabecular bone mass is close to maximum loss (around 50%) already by day 11, in the absence of metastasis. These results support the possibility of T cell involvement in pre-metastatic lesion. Indeed, in vitro, BM T cells from 4T1+ mice, but not from 67NR+, could induce OC differentiation in response to tumor antigens ascertained by TRAP enzymatic activity, morphology and osteolytic disk assay. In vivo transfer experiments showed that T cells from 4T1+ mice (Day 11), when transferred into nude mice produce 3 times more IL17F and 4 times more RANKL than donor 67NR+ T cells. Moreover, trabecular bone at day 14 after transfer of 4T1+T cells was already 30% that of normal nude mice in contrast to 100% from 67NR+ T cells. Of note is the fact that these activities are achieved in the absence of the metastatic 4T1 tumor in the nude host, but challenged with either 67NR or protein antigen extract.

To address the role of T cell derived IL17F and RANKL, T cells from 4T1 bearing mice (day 11) were silenced with shRNA specific for each of these cytokines and transferred into nude mice. Animals were challenged with soluble tumor antigen. Silencing IL17F had no effect over bone loss. However, RANKL silencing completely inhibited osteolytic lesions. Together, these results indicate that RANKL in T cells mediate the osteolytic lesions and that cancer induced bone disease can be metastasis independent.

Since osteolytic lesions are believed to be important to feed the tumor with growth factors in a vicious cycle established in the metastatic niche, we asked if T cells could be preparing the pre-metastatic niche. When 4T1 cells are injected into athymic nude mice, bone metastasis is not observed up to day 24, while by day 20 it is already present in euthymic BALB/c animals, indicating that T cells are critical to prepare the seeding soil for tumor cells within the bone. We are currently investigating the role of T cells in the establishment of metastasis at later time points as well as in the primary tumor growth. Our results strongly suggest that tumor cells, according to its metastatic activity, can modulate T cell activity systemically. Moreover, and not less important, we show that cancer induced bone disease starts before metastatic colonization and is mediated by RANKL expressed in tumor specific T cells. We propose that this is the very first step on the establishment of the “vicious cycle” which will allow tumor growth.

We believe this work can open new avenues on the prognostic evaluation and treatment of women with breast cancer.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P1-01-02.

Validity of MicroCT for in vitro detection of proximal carious lesions in primary molars

OBJECTIVE

This study aimed to validate the MicroCT for detection of proximal carious lesions in primary molars, using histology as the gold standard.

METHODS

Forty-eight proximal surfaces of primary molars were examined. Two calibrated examiners conducted the examinations independently. Proximal surfaces were visually scored, using ICDAS. Bitewing radiographs, Micro-CT and histological analyses used caries scores: 0=sound; 1=outer enamel; 2=inner enamel; 3=not spread dentine; 4=outer dentine; 5=inner dentine. Axial and sagital images were used for Micro-CT analysis, whilst for histology, tooth sections (400μm) were analyzed stereomicroscopically (×15).

RESULTS

Inter-examiner agreement ranged from 0.87 to 0.93 kappa coefficient (k). Histological analysis revealed a frequency of sound tooth surfaces (18.8%) enamel carious lesions (E1) (48%) and dentine carious lesions (D1) (33.3%). MicroCT showed high correlation with histology (r(s)0.88). At both diagnostic thresholds (E1 and D1), sensitivity and accuracy were higher for MicroCT. Inter-device agreement between MicroCT and histology was k=0.81. No difference was found between MicroCT and histology as gold standards for detecting carious lesions using ICDAS.

CONCLUSION

MicroCT can be used as a gold standard for detecting carious lesions in proximal surfaces in primary molars.

In vitro antifungal activity and toxicity of itraconazole in DMSA-PLGA nanoparticles

Itraconazole (ITZ) is a drug used to treat various fungal infections and may cause side effects. The aim of this study was to develop and evaluate the in vitro activity of DMSA-PLGA nanoparticles loaded with ITZ against Paracoccidioides brasiliensis, as well as their cytotoxicity. Nanoparticles were prepared using the emulsification-evaporation technique and characterized by their encapsulation efficiency, morphology (TEM), size (Nanosight) and charge (zeta potential). Antifungal efficacy in P. brasiliensis was determined by minimal inhibition concentration (MIC), and cytotoxicity using MTT assay. ITZ was effectively incorporated in the PLGA-DMSA nanoparticles with a loading efficiency of 72.8 +/- 3.50%. The shape was round with a solid polymeric structure, and a size distribution of 174 +/- 86 nm (Average +/- SD). The particles were negatively charged. ITZ-NANO presented antifungal inhibition (MIC = 6.25 ug/mL) against P. brasiliensis and showed lower in vitro cytotoxicity than free drug (ITZ).

Spectroscopic study of maghemite nanoparticles surface-grafted with DMSA

Nanosized maghemite (below 10 nm average diameter), surface-functionalized with meso-2,3-dimercaptosuccinic acid (DMSA), was investigated with respect to the content of DMSA molecules attached onto its surface and the onset of S-S bridges due to oxidation of neighboring S-H groups. To support our investigation, we introduced the use of photoacoustic spectroscopy to monitor thiol groups (S-H) conjugated with Raman spectroscopy to monitor the disulfide bridges (S-S). The normalized intensity (N(R)) of the Raman feature peaking at 500 cm(-1) was used to probe the S-S bridge whereas the normalized intensity (N(P)) of the photoacoustic band-S (0.42-0.65 μm) was used to probe the S-H moiety. The perfect linearity observed in the N(R) versus (1 - N(P)) plot strongly supports the oxidation process involving neighboring S-H groups as the DMSA surface grafting coefficient increases whereas the approach used in this report allows the evaluation of the [S-H]/[S-S] ratio. The observation of the reduction of the hydrodynamic diameter as the nominal DMSA-grafting increases supports the proposed model picture, in which the intraparticle (interparticle) S-S bridging takes place at higher (lower) DMSA-grafting values.

Anti-proliferative and cytotoxic activity of pentadactylin isolated from Leptodactylus labyrinthicus on melanoma cells

Nowadays, the emergence of resistance to the current available chemotherapeutic drugs by cancer cells makes the development of new agents imperative. The skin secretion of amphibians is a natural rich source of antimicrobial peptides (AMP), and researchers have shown that some of these wide spectrum molecules are also toxic to cancer cells. The aim of this study was to verify a putative anticancer activity of the AMP pentadactylin isolated for the first time from the skin secretion of the frog Leptodactylus labyrinthicus and also to study its cytotoxic mechanism to the murine melanoma cell line B16F10. The results have shown that pentadactylin reduces the cell viability of B16F10 cells in a dose-dependent manner. It was also cytotoxic to normal human fibroblast cells; nevertheless, pentadactylin was more potent in the first case. The studies of action mechanism revealed that pentadactylin causes cell morphology alterations (e.g., round shape and shrinkage morphology), membrane disruption, DNA fragmentation, cell cycle arrest at the S phase, and alteration of mitochondrial membrane potential, suggesting that B16F10 cells die by apoptosis. The exact mechanism that causes reduction of cell viability and cytotoxicity after treatment with pentadactylin is still unknown. In conclusion, as cancer cells become resilient to death, it is worthwhile the discovery of new drugs such as pentadactylin that induces apoptosis.