Valbert Nascimento Cardoso

Time-dependent migration of systemically delivered bone marrow mesenchymal stem cells to the infarcted heart.

In this study the time course of homing and the body distribution of systemically delivered bone marrow mesenchymal stem cells (BM-MSCs) after myocardial infarction (MI) were evaluated. BM-MSCs were isolated from Wistar rats, expanded in vitro, and their phenotypical characterization was performed by flow cytometer. Rats were randomly divided into three groups: control, sham MI, and MI. BM-MSCs (5 × 106) were labeled with 99mTc-HMPAO and injected through the tail vein 7 days after MI. Gamma camera imaging was performed at 5, 15, 30, and 60 min after cell inoculation. Due to the 99mTc short half-life, cell migration and location were also evaluated in heart sections using DAPI-labeled cells 7 days after transplantation. Phenotypical characterization showed that BM-MSCs were CD90+, CD73+, CD54+, and CD45-. Five minutes after 99mTc-HMPAO-labeled cell injection, they were detected in various tissues. The cells migrated mainly to the lungs (approximately 70%) and, in small amounts, to the heart, kidneys, spleen, and bladder. The number of cells in the heart and lungs decreased after 60 min. MI markedly increased the amount of cells in the heart, but not in the lungs, during the period of observation (4.55 ± 0.32 vs. 6.34 ± 0.67% of uptake in infarcted hearts). No significant differences were observed between control and sham groups. Additionally, 7 days after DAPI-labeled cells injection, they were still detected in the heart but only in infarcted areas. These results suggest that the migration of systemically delivered BM-MSCs to the heart is time dependent and MI specifically increases BM-MSCs homing to injured hearts. However, the systemic delivery is limited by cell entrapment in the lungs.

Emerging role of radiolabeled nanoparticles as an effective diagnostic technique

Nanomedicine is emerging as a promising approach for diagnostic applications. Nanoparticles are structures in the nanometer size range, which can present different shapes, compositions, charges, surface modifications, in vitro and in vivo stabilities, and in vivo performances. Nanoparticles can be made of materials of diverse chemical nature, the most common being metals, metal oxides, silicates, polymers, carbon, lipids, and biomolecules. Nanoparticles exist in various morphologies, such as spheres, cylinders, platelets, and tubes. Radiolabeled nanoparticles represent a new class of agent with great potential for clinical applications. This is partly due to their long blood circulation time and plasma stability. In addition, because of the high sensitivity of imaging with radiolabeled compounds, their use has promise of achieving accurate and early diagnosis. This review article focuses on the application of radiolabeled nanoparticles in detecting diseases such as cancer and cardiovascular diseases and also presents an overview about the formulation, stability, and biological properties of the nanoparticles used for diagnostic purposes.

Drug interaction with radiopharmaceuticals: a review

Clinical images are worthwhile in Health Sciences and their analysis and correct interpretation aid the professionals,such as physicians, physiotherapists and occupational therapists, to make decisions and take subsequent therapeutic and/or rehabilitation measures. Other factors, besides the state of the disease, may interfere and affect the bioavailability of the radiopharmaceuticals (radiobiocomplexes) and the quality of the SPECT and PET images. Furthermore, the labeling of some of these radiobiocomplexes, such as plasma proteins, white blood cells and red blood cells, with 99mT, can also be modified. These factors include drugs (synthetic and natural) and dietary conditions, as well as some medical procedures (invasive or non-invasive), such as radiation therapy, surgical procedures, prostheses, cardioversion, intubation, chemoperfusion, external massage, immunotherapy, blood transfusion and hemodialysis. In conclusion, the knowledge about these factors capable of interfering with the bioavailability of the radiobiocomplexes is worthwhile for secure diagnosis. Moreover, the development of biological models to study these phenomena is highly relevant and desirable.

Assessment of the effect of Fucus vesiculosus extract on the labeling of blood constituents with technetium-99m and the histological modifications on the shape of the red blood cells.

Natural products are widely used as food or food additives or medicines for humans. We are trying to develop a model to assess the possible toxic properties of natural products, such as Fucus vesiculosus, utilized in popular medicine. Red blood cells (RBC) labeled with technetium-99m (99mTc) are used in various procedures in nuclear medicine. This labeling procedure depends on a reducing agent, and stannous chloride is used. There is evidence that this labeling may be altered by drugs. We have investigated the possibility that F. vesiculosus extract is capable of altering the labeling of blood elements with 99mTc. Blood was incubated with F. vesiculosus extract and stannous chloride solution and Tc-99m added. Blood was centrifuged and plasma (P) and blood cells (BC) were isolated. Samples of P or BC were also precipitated, centrifuged and insoluble (IF) and soluble (SF) were separated. The percentages of radioativity (%ATI) in BC, IF-P and IF-BC were calculated. Histological preparations of the RBC treated with F. vesiculosus revealed that this extract is capable of promoting important modifications on the shape of the RBC. The%ATI decreased on BC from 93.6+/-2.3 to 29.0+/-2.7, on IF-P from 77.6+/-1.2 to 7.5+/-1.0 and on IF-BC from 80.0+/-3.4 to 12.6+/-4.8. Once the RBC labeling procedure with 99mTc depends on the presence of stannous (+2) ions, the substances present in the F. vesiculosus extract should increase the valence of these ions to stannic (+4). This would decrease the%ATI on blood elements and indicate the presence of oxidant agents in the F. vesiculosus extract.

Assessment of the effect of Maytenus ilicifolia (espinheira santa) extract on the labeling of red blood cells and plasma proteins with technetium-99m.

We are trying to develop a model to assess properties of products utilized in popular medicine. Maytenus ilicifolia is used in herbal medicine. Red blood cells (RBC) labeled with technetium-99m (99mTc) are employed in nuclear medicine. This labeling procedure depends on a reducing agent and stannous chloride is used. There is evidence that this labeling may be altered by drugs. We have investigated the possibility of M. ilicifolia extract being capable to alter the labeling of blood elements with 99mTc. Blood was incubated with M. ilicifolia extract. Stannous chloride solution and Tc-99m were added. Blood was centrifuged and plasma (P) and blood cells (C) were isolated. Samples of P or C were also precipitated, centrifuged and insoluble (IF) and soluble (SF) were separated. The percentages of radioactivity (%ATI) in C, IF-P and IF-C was calculated. The %ATI decreased on C from 93.6+/-2.3 to 29.0+/-2.7, on IF-P from 77.6+/-1.2 to 7.5+/-1.0 and on IF-C from 80.0+/-3.4 to 12.6+/-4.8. Once in RBC labeling procedure with 99mTc depends on the presence of stannous (+2) ions, the substances of the M. ilicifolia extract could increase the valence these ions to stannic (+4). This fact would decrease the %ATI on blood elements and indicate the presence of oxidant agents in the M. ilicifolia extract.

Effect of age on body distribution of Tityustoxin from Tityus serrulatus scorpion venom in rats.

Previous research from our Laboratory has shown a greater susceptibility of young animals, when compared to adults, to envenomation by tityustoxin (TsTX), one of the main toxins from Tityus serrulatus scorpion venom. Our hypothesis is that a differential body distribution of TsTX among adult and young animals could account for the worse prognosis of scorpion envenomation in infants. Thus, TsTX labeled with technetium-99m was injected (6 microg, subcutaneous) in adult (150-160 day-old) and young (21-22 day-old) male rats. Groups of animals were sacrificed at different times after TsTX injection (0.08, 1.0, 3.0, 6.0, 12.0 and 24.0 hours) under Urethane anesthesia (140 mg/100 g, i.p.). The brain, heart, lungs, liver, kidneys, spleen and thyroid were excised and blood collected. Young rats presented a shorter latency toxin concentration peak in all studied organs except for the liver and the kidney, when compared to adults. The ratio between the area under the curve of the toxin concentration in each organ and that in blood (Kp) indicates higher accumulation in the organs of young animals mainly for brain, liver and heart. These observations suggest a faster toxin distribution in the organs of young rats. The higher uptake of TsTX in the brain is suggestive of a greater permeability for the toxin along the blood-brain barrier of young rats. In conclusion, the higher uptake in heart, together with data from the brain, may help to elucidate the clinical manifestations frequently observed in children under scorpion envenomation.

Effect of extract of medicinal plants on the labeling of blood elements with Technetium-99m and on the morphology of red blood cells: I—a study with Paullinia cupana

Drugs can alter the labeling and the morphology of red blood cells. As Paullinia cupana is used in popular medicine, we evaluated its influence on the labeling process using technetium-99m (Tc-99m). Blood was incubated with P. cupana, stannous chloride and Tc-99m. Samples were centrifuged and plasma (P) and blood cells (BC) were separated and precipitated with trichloroacetic acid. Soluble (SF) and insoluble fractions (IF) were isolated. The morphology of the blood cells was evaluated under an optical microscope. The results showed a significant (P = 0.05) decrease in the uptake of radioactivity for the RBC (97.93 +/- 0.74 to 36.90 +/- 4.71%), in IF-P and in IF-BC due to P. cupana extract. The study of the morphology of the RBC revealed alterations in the shape of these cells. We suggest that the P. cupana effect could be explained by an inhibition of the stannous and pertechnetate ions or oxidation of the stannous ion or by damages in the plasma membrane.

Glutamine Supplementation Decreases Intestinal Permeability and Preserves Gut Mucosa Integrity in an Experimental Mouse Model

BACKGROUND Glutamine (GLN) is the preferred fuel for enterocytes, and GLN supplementation is critical during stressful conditions. The aim of this study was to evaluate the effect of GLN on intestinal barrier permeability and bacterial translocation in a murine experimental model. METHODS Swiss male mice (25-30 g) were randomized into 3 groups: (1) sham group; (2) intestinal obstruction (IO) group; (3) IO and GLN (500 mg/kg/d) group. Two different experiments were carried out to assess intestinal permeability and bacterial translocation. In the first experiment, the animals were divided into the 3 groups described above and received diethylenetriamine pentaacetate radiolabeled with technetium ((99m)Tc) on the eighth day. At different time points after intestinal obstruction, blood was collected to determine radioactivity. The animals were killed, and the small intestine was removed for histological analyses. In the bacterial translocation study, on the eighth day all groups received Escherichia coli labeled with (99m)Tc. After 90 minutes, the animals underwent intestinal obstruction and were killed 18 hours later. Blood, mesenteric lymph nodes, liver, spleen, and lungs were removed to determine radioactivity. Statistical significance was considered when P < or = .05. RESULTS The levels of intestinal permeability and bacterial translocation were higher in the IO group than in the sham and GLN groups (P < .05). GLN decreased intestinal permeability and bacterial translocation to physiologic levels in the treated animals and preserved intestinal barrier integrity. CONCLUSIONS GLN had a positive impact on the intestinal barrier by reducing permeability and bacterial translocation to physiologic levels and preserving mucosal integrity.

Pretreatment with arginine preserves intestinal barrier integrity and reduces bacterial translocation in mice

OBJECTIVE To evaluate the effects of arginine on intestinal barrier integrity and bacterial translocation (BT) in mice undergoing intestinal obstruction. METHODS Mice were divided into 3 groups, treated for 7 d before surgical intervention with isocaloric and isoprotein diets. The ARG group received a diet containing 2% arginine, the IO (intestinal obstruction) and Sham groups, standard chow diet. On the eighth day of treatment, all animals received diethylenetriamine pentaacetic acid (DTPA) solution labeled with 99mTechnetium (99mTc-DTPA) by gavage for intestinal permeability analysis. After 90 min, the animals were anesthetized and the terminal ileum ligated. The Sham group only underwent laparotomy. After 4, 8, and 18 h, blood was collected for radioactivity determination. Samples of ileum were collected 18 h after surgery for histological analysis. In another set of animals, BT was evaluated. After 7 d of treatment, all animals received 10(8) CFU/mL of 99mTc-E.coli by gavage; 90 min later they were submitted to the surgical procedure described above. BT was determined by the uptake of 99mTc-E.coli in blood, mesenteric lymph nodes, liver, spleen, and lungs, assessed 18 h after the surgery. RESULTS The intestinal permeability and BT were higher in the IO group when compared with the Sham group (P < 0.05). Arginine supplementation reduced intestinal permeability and BT to physiologic levels. Histological analysis showed mucosal ileum preservation in animals treated with arginine. CONCLUSION Arginine was able to preserve barrier integrity, thus reducing BT.

Antiglaucomatous effects of the activation of intrinsic Angiotensin-converting enzyme 2.

PURPOSE To evaluate the effects of the activation of endogenous angiotensin-converting enzyme 2 (ACE2) using the compound diminazene aceturate (DIZE) in an experimental model of glaucoma in Wistar rats. METHODS DIZE (1 mg/kg) was administered daily, either systemically or topically, and the IOP was measured weekly. To examine the role of the Mas receptor in the effects of DIZE, the Ang-(1-7) antagonist A-779 was co-administered. Drainage of the aqueous humor was evaluated by using scintigraphy. The analysis of ACE2 expression by immunohistochemistry and the counting of retinal ganglion cells (RGCs) were performed in histologic sections. Additionally, the nerve fiber structure was evaluated by transmission electron microscopy. RESULTS The systemic administration and topical administration (in the form of eye drops) of DIZE increased the ACE2 expression in the eyes and significantly decreased the IOP of glaucomatous rats without changing the blood pressure. Importantly, this IOP-lowering action of DIZE was similar to the effects of dorzolamide. The antiglaucomatous effects of DIZE were blocked by A-779. Histologic analysis revealed that the reduction in the number of RGCs and the increase in the expression of caspase-3 in the RGC layer in glaucomatous animals were prevented by DIZE. This compound also prevented alterations in the cytoplasm of axons in glaucomatous rats. In addition to these neuroprotective effects, DIZE facilitated the drainage of the aqueous humor. CONCLUSIONS Our results evidence the pathophysiologic relevance of the ocular ACE2/Ang-(1-7)/Mas axis of the renin-angiotensin system and, importantly, indicate that the activation of intrinsic ACE2 is a potential therapeutic strategy to treat glaucoma.