Nivaldo A Parizotto | UFSCar - Federal University of São Carlos (original) (raw)

Papers by Nivaldo A Parizotto

Journal of Biomedical Materials Research Part B: Applied Biomaterials, 2015

This study evaluated the effects of the Biosilicate V R and poly (D,L-lactic-co-glycolic) acid co... more This study evaluated the effects of the Biosilicate V R and poly (D,L-lactic-co-glycolic) acid composites on bone repair in a tibial bone defect model in rats by means of using histological evaluation (histopathological and morphometric analysis) and gene expression analysis. Eighty male Wistar rats (12 weeks old, weighing 6300 g) were randomly divided into two groups: Biosilicate V R group (BG) and Biosilicate V R / PLGA group (BG/PLGA). Each group was euthanized at 3, 7, 14, and 21 days after surgery (n 5 10 animals per time point).

Journal of Photochemistry and Photobiology B: Biology, 2015

Obesity affects approximately 20% of the world population, and exercise is the primary non-pharma... more Obesity affects approximately 20% of the world population, and exercise is the primary non-pharmacological therapy. The combined use of exercise and low-level laser therapy (LLLT) may potentiate the effects promoted by exercise. The objective of this study was to investigate the effects of exercise in combination with phototherapy on adipocyte area, activity of the enzyme citrate synthase and muscle morphological analysis. We used 64 Wistar rats, which were divided into eight groups with 8 rats each: sedentary chow-diet (SC); sedentary chow-diet plus laser therapy (SCL), exercised chow-diet (EC); exercised chow-diet plus laser therapy (ECL); sedentary high-fat diet (SH); sedentary high-fat diet plus laser therapy (SHL); exercised high-fat diet (EH); exercised high-fat diet, laser therapy (EHL). The animals were submitted to a program of swimming training for 90 min/5 times per week for 8 weeks and LLLT (GA-Al-AS, 830 nm) at a dose of 4.7 J/point and a total energy of 9.4 J/animal, with duration of 47 s, which was applied to both gastrocnemius muscles after exercise. We conclude that the combined use of exercise and phototherapy increases the activity of the enzyme citrate synthase and decreases the white adipocyte area epididymal, retroperitoneal and visceral in obese rats, enhancing the effects of exercise.

Guide for Clinical Practice, 2015

Photomedicine and Laser Surgery, 2013

Objective: This study aimed to investigate the in vivo tissue performance of the association of B... more Objective: This study aimed to investigate the in vivo tissue performance of the association of Biosilicate Ò scaffolds and low-level laser therapy (LLLT) in a tibial bone defects model in rats. Background data: Many studies have been demonstrating the osteogenic potential of Biosilicate and LLLT. However, there is a need to investigate the effects of both treatments for bone consolidation. Methods: The animals were divided into control group (CG), Biosilicate scaffold group (BG), and Biosilicate scaffolds plus LLLT group (BLG). Animals were euthanized after 15, 30, and 45 days post-injury. Results: The histological analysis revealed that all the experimental groups showed inflammatory infiltrate and granulation tissue, at the area of the defect at day 15. After 30 days, CG still showed granulation tissue and bone ingrowth. Both Biosilicate groups presented newly formed bone and interconected trabeculae. At 45 days, CG showed immature newly formed bone. A more mature newly formed bone was observed in BG and BLG. On day 15, BG demonstrated a statistically higher expression of cyclooxygenase (COX)-2 compared with CG and BLG. No statistically significant difference was observed in COX-2 immunoexpression among the groups at 30 and 45 days. Similar expression of bone morphogenetic protein (BMP)-9 was demonstrated for all experimental groups at 15 and 30 days. At 45 days, the BMP-9 immunoexpression was statistically upregulated in the BLG compared with the CG and BG. No statistically significant difference was observed in the receptor activator of nuclear factor kappa-B ligand (RANKL) immunoexpression among the groups in all periods evaluated. Biosilicate groups presented a decrease in biomechanical properties compared with CG at 30 and 45 days post-surgery. Conclusions: Our findings suggest that Biosilicate presented osteogenic activity, accelerating bone repair. However, laser therapy was not able to enhance the bioactive properties of the Biosilicate.

Applied Biochemistry and Biotechnology, 1998

Atomic force microscopy was used to study the geometric structure of collagen fibrils and molecul... more Atomic force microscopy was used to study the geometric structure of collagen fibrils and molecules of rat calcanean tendon tissues. The authors found that the diameter of the fibrils ranged from 124 to 170 nm, and their geometric form suggested a helical winding with spectral period from 59.4 to 61.7 nm, close to the band dimensions reported by electron microscopy. At high magnification, the surface of these bands revealed images that probably correspond to the almost crystalline array of collagen molecules, with the triple helix structure almost visible. The typical helix width is 1.43 nm, with main periods of 1.15 and 8.03 nm, very close to the dimensions reported by X-ray diffraction.

Revista Brasileira de Ortopedia, 2012

Physiotherapy theory and practice, Jan 14, 2015

Recently, low-level laser (light) therapy (LLLT) has been used to improve muscle performance. Thi... more Recently, low-level laser (light) therapy (LLLT) has been used to improve muscle performance. This study aimed to evaluate the effectiveness of near-infrared light-emitting diode therapy (LEDT) and its mechanisms of action to improve muscle performance in an elite athlete. The kinetics of oxygen uptake (VO 2 ), blood and urine markers of muscle damage (creatine kinase -CK and alanine) and fatigue (lactate) were analyzed. Additionally, some metabolic parameters were assessed in urine using proton nuclear magnetic resonance spectroscopy ( 1 H NMR). A LED cluster with 50 LEDs ( ¼ 850 nm; 50 mW 15 s; 37.5 J) was applied on legs, arms and trunk muscles of a single runner athlete 5 min before a high-intense constant workload running exercise on treadmill. The athlete received either Placebo-1-LEDT; Placebo-2-LEDT; or Effective-LEDT in a randomized double-blind placebo-controlled trial with washout period of 7 d between each test. LEDT improved the speed of the muscular VO 2 adaptation ($À9 s), decreased O 2 deficit ($À10 L), increased the VO 2 from the slow component phase ($+348 ml min À1 ) and increased the time limit of exercise ($+589 s). LEDT decreased blood and urine markers of muscle damage and fatigue (CK, alanine and lactate levels). The results suggest that a muscular pre-conditioning regimen using LEDT before intense exercises could modulate metabolic and renal function to achieve better performance.

Applied Surface Science, 2000

In this work, we investigated the effects of He-Ne laser irradiation on the inflammatory process ... more In this work, we investigated the effects of He-Ne laser irradiation on the inflammatory process induced in the articular cartilage of the right knee of guinea pigs. Through electron microscopy analysis it was possible to identify the induced arthritis in the articular cartilage and its modification after the laser treatment. The laser radiation promoted a reduction in the proliferation of the inflammatory cells in the damaged tissue and also induced the formation of cartilage bridges that tied the destroyed parts favoring the formation of a repaired tissue in the injured cartilage. q

Journal of Materials Science: Materials in Medicine, 2015

The aim of this study was to evaluate the effects of highly porous Biosilicate Ò scaffolds on bon... more The aim of this study was to evaluate the effects of highly porous Biosilicate Ò scaffolds on bone healing in a tibial bone defect model in rats by means of histological evaluation (histopathological and immunohistochemistry analysis) of the bone callus and the systemic inflammatory response (immunoenzymatic assay). Eighty Wistar rats (12 weeks-old, weighing ±300 g) were randomly divided into 2 groups (n = 10 per experimental group, per time point): control group and Biosilicate Ò group (BG). Each group was euthanized 3, 7, 14 and 21 days post-surgery. Histological findings revealed a similar inflammatory response in both experimental groups, 3 and 7 days post-surgery. During the experimental periods (3-21 days post-surgery), it was observed that the biomaterial degradation, mainly in the periphery region, provided the development of the newly formed bone into the scaffolds. Immunohistochemistry analysis demonstrated that the Biosilicate Ò scaffolds stimulated cyclooxygenase-2, vascular endothelial growth factor and runtrelated transcription factor 2 expression. Furthermore, in the immunoenzymatic assay, BG presented no difference in the level of tumor necrosis factor alpha in all experimental periods. Still, BG showed a higher level of interleukin 4 after 14 days post-implantation and a lower level of interleukin 10 in 21 days post-surgery. Our results demonstrated that Biosilicate Ò scaffolds can contribute for bone formation through a suitable architecture and by stimulating the synthesis of markers related to the bone repair.

Journal of Biomedical Materials Research Part A, 2013

This study aimed to evaluate the osteointegration and genotoxic potential of a bioactive scaffold... more This study aimed to evaluate the osteointegration and genotoxic potential of a bioactive scaffold, composed of alumina and coated with hydroxyapatite and bioglass, after their implantation in tibias of rats. For this purpose, Wistar rats underwent surgery to induce a tibial bone defect, which was filled with the bioactive scaffolds. Histology analysis (descriptive and morphometry) of the bone tissue and the single-cell gel assay (comet) in multiple organs (blood, liver, and kidney) were used to reach this aim after a period of 30, 60, 90, and 180 days of material implantation. The main findings showed that the incorporation of hydroxyapatite and bioglass in the alumina scaffolds produced a suitable environment for bone ingrowth in the tibial defects and did not demonstrate any genotoxicity in the organs evaluated in all experimental periods. These results clearly indicate that the bioactive scaffolds used in this study present osteogenic potential and still exhibit local and systemic biocompatibility. These findings are promising once they convey important information about the behavior of this novel biomaterial in biological system and highlight its possible clinical application. V C 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 00A:000-000, 2013.

Lasers in Medical Science, 2013

Background and Objective: Muscle regeneration is a complex phenomenon, involving coordinated acti... more Background and Objective: Muscle regeneration is a complex phenomenon, involving coordinated activation of several cellular responses. During this process, oxidative stress and consequent tissue damage occur with a severity that may depend on the intensity and duration of the inflammatory response. Among the therapeutic approaches to attenuate inflammation and increase tissue repair, low-level laser therapy (LLLT) may be a safe and effective clinical procedure. The aim of this study was to evaluate the effects of LLLT on oxidative/nitrative stress and inflammatory mediators produced during a cryolesion of the tibialis anterior (TA) muscle in rats. Material and Methods: Sixty Wistar rats were randomly divided into three groups (n ¼ 20): control (BC), injured TA muscle without LLLT (IC), injured TA muscle submitted to LLLT (IRI). The injured region was irradiated daily for 4 consecutive days, starting immediately after the lesion using a AlGaAs laser (continuous wave, 808 nm, tip area of 0.00785 cm 2 , power 30 mW, application time 47 seconds, fluence 180 J/cm 2 ; 3.8 mW/cm 2 ; and total energy 1.4 J). The animals were sacrificed on the fourth day after injury. Results: LLLT reduced oxidative and nitrative stress in injured muscle, decreased lipid peroxidation, nitrotyrosine formation and NO production, probably due to reduction in iNOS protein expression. Moreover, LLLT increased SOD gene expression, and decreased the inflammatory response as measured by gene expression of NF-kb and COX-2 and by TNF-a and IL-1b concentration. Conclusion: These results suggest that LLLT could be an effective therapeutic approach to modulate oxidative and nitrative stress and to reduce inflammation in injured muscle. Lasers Surg. Med. 44:726-735, 2012.

Journal of Photochemistry and Photobiology B: Biology, 2013

It is known that low level laser therapy is able to improve skin flap viability by increasing ang... more It is known that low level laser therapy is able to improve skin flap viability by increasing angiogenesis. However, the mechanism for new blood vessel formation is not completely understood. Here, we investigated the effects of 660 nm and 780 nm lasers at fluences of 30 and 40 J/cm 2 on three important mediators activated during angiogenesis. Sixty male Wistar rats were used and randomly divided into five groups with twelve animals each. Groups were distributed as follows: skin flap surgery non-irradiated group as a control; skin flap surgery irradiated with 660 nm laser at a fluence of 30 or 40 J/cm 2 and skin flap surgery irradiated with 780 nm laser at a fluence of 30 or 40 J/cm 2 . The random skin flap was performed measuring 10 Â 4 cm, with a plastic sheet interposed between the flap and the donor site. Laser irradiation was performed on 24 points covering the flap and surrounding skin immediately after the surgery and for 7 consecutive days thereafter. Tissues were collected, and the number of vessels, angiogenesis markers (vascular endothelial growth factor, VEGF and hypoxia inducible factor, HIF-1a) and a tissue remodeling marker (matrix metalloproteinase, MMP-2) were analyzed. LLLT increased an angiogenesis, HIF-1a and VEGF expression and decrease MMP-2 activity. These phenomena were dependent on the fluences, and wavelengths used. In this study we showed that LLLT may improve the healing of skin flaps by enhancing the amount of new vessels formed in the tissue. Both 660 nm and 780 nm lasers were able to modulate VEGF secretion, MMP-2 activity and HIF-1a expression in a dose dependent manner.

Lasers in Surgery and Medicine, 2014

Conclusion: These results provide evidence for the positive benefits of LLLT and HIT with respect... more Conclusion: These results provide evidence for the positive benefits of LLLT and HIT with respect to enhanced muscle metabolic and cardiac autonomic function in Wistar rats. Lasers Surg. Med.

Journal of Biomedical Materials Research Part B: Applied Biomaterials, 2011

This study aimed to investigate bone responses to a novel bioactive fully crystallized glass-cera... more This study aimed to investigate bone responses to a novel bioactive fully crystallized glass-ceramic of the quaternary system P 2 O 5 -Na 2 O-CaO-SiO 2 (Biosilicate V R ). Although a previous study demonstrated positive effects of Biosilicate V R on in vitro bone-like matrix formation, its in vivo effect was not studied yet. Male Wistar rats (n ¼ 40) with tibial defects were used. Four experimental groups were designed to compare this novel biomaterial with a gold standard bioactive material (Bioglass V R 45S5), unfilled defects and intact controls. A three-point bending test was performed 20 days after the surgical procedure, as well as the histomorphometric analysis in two regions of interest: cortical bone and medullary canal where the particulate biomaterial was implanted. The biomechanical test revealed a significant increase in the maximum load at failure and stiffness in the Biosilicate V R group (vs. control defects), whose values were similar to uninjured bones. There were no differences in the cortical bone parameters in groups with bone defects, but a great deal of woven bone was present surrounding Biosilicate V R and Bioglass V R 45S5 particulate. Although both bioactive materials supported significant higher bone formation; Biosilicate V R was superior to Bioglass V R 45S5 in some histomorphometric parameters (bone volume and number of osteoblasts). Regarding bone resorption, Biosilicate V R group showed significant higher number of osteoclasts per unit of tissue area than defect and intact controls, despite of the non-significant difference in the osteoclastic surface as percentage of bone surface. This study reveals that the fully crystallized Biosilicate V R has good bone-forming and bone-bonding properties. V C 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 97B: 139-147, 2011.

Photonics and Lasers in Medicine, 2000

Photochemistry and Photobiology, 2014

Low-level laser (light) therapy has been used before exercise to increase muscle performance in b... more Low-level laser (light) therapy has been used before exercise to increase muscle performance in both experimental animals and in humans. However, uncertainty exists concerning the optimum time to apply the light before exercise. The mechanism of action is thought to be stimulation of mitochondrial respiration in muscles, and to increase adenosine triphosphate (ATP) needed to perform exercise. The goal of this study was to investigate the time course of the increases in mitochondrial membrane potential (MMP) and ATP in myotubes formed from C2C12 mouse muscle cells and exposed to light-emitting diode therapy (LEDT). LEDT employed a cluster of LEDs with 20 red (630 AE 10 nm, 25 mW) and 20 near-infrared (850 AE 10 nm, 50 mW) delivering 28 mW cm 2 for 90 s (2.5 J cm 2 ) with analysis at 5 min, 3 h, 6 h and 24 h post-LEDT. LEDT-6 h had the highest MMP, followed by LEDT-3 h, LEDT-24 h, LEDT-5 min and Control with significant differences. The same order (6 h > 3 h > 24 h > 5 min > Control) was found for ATP with significant differences. A good correlation was found (r = 0.89) between MMP and ATP. These data suggest an optimum time window of 3-6 h for LEDT stimulate muscle cells.

Photonics & Lasers in Medicine, 2014

The aim of this study was to evaluate the effects of low level laser therapy (LLLT) on the degene... more The aim of this study was to evaluate the effects of low level laser therapy (LLLT) on the degenerative process in the articular cartilage after an anterior cruciate ligament transection (ACLT) model in rats.

Lasers in Medical Science, 2015

Low-level laser (light) therapy (LLLT) has been applied over skeletal muscles before intense exer... more Low-level laser (light) therapy (LLLT) has been applied over skeletal muscles before intense exercise (muscular pre-conditioning) in order to reduce fatigue and muscle damage (measured by creatine kinase, CK) in clinical trials. However, previous exercise protocols do not exactly simulate the real muscle demand required in sports. For this reason, the aim of this randomized and double-blind placebocontrolled trial was to investigate whether light-emitting diode therapy (LEDT) applied over the quadriceps femoris muscles, hamstrings, and triceps surae of volleyball players before official matches could prevent muscle damage (CK) with a dose response, establishing a therapeutic window. A professional male volleyball team (12 athletes) was enrolled in this study, and LEDT was applied before 4 matches during a national championship. LEDT used an array of 200 lightemitting diodes (LEDs) arranged in 25 clusters of 4 infrared LEDs (850±20 nm; 130 mW) and 25 clusters of 4 red LEDs (630±10 nm; 80 mW). Athletes were randomized to receive one of four different total doses over each muscle group in a double-blind protocol: 105 J (20 s), 210 J (40 s), 315 J (60 s), and placebo (no light for 30 s). CK in blood was assessed 1 h before and 24 h after each match. LEDT at 210 J avoided significant increases in CK (+10 %; P=0.993) as well as 315 J (+31 %, P=0.407). Placebo (0 J) allowed a significant increase in CK (+53 %; P=0.012) as well as LEDT at 105 J (+ 59 %; P=0.001). LEDT prevented significant increases of CK in blood in athletes when applied before official matches with a light dose response of 210-315 J, suggesting athletes might consider applying LEDT before competition.