Biomedical subjects

R L Cabrini

Publications and source records attributed to R L Cabrini.

At least 19 recordsLinked to original sources

PubMed2006

Ultrastructural and metabolic changes in osteoblasts exposed to uranyl nitrate.

Exposure to uranium is an occupational hazard to workers who continually handle uranium and an environmental risk to the population at large. Since the cellular and molecular pathways of uranium toxicity in osteoblast cells are still unknown, the aim of the present work was to evaluate the adverse effects of uranyl nitrate (UN) on osteoblasts both in vivo and in vitro. Herein we studied the osteoblastic ultrastructural changes induced by UN in vivo and analyzed cell proliferation, generation of reactive oxygen species (ROS), apoptosis, and alkaline phosphatase (APh) activity in osteoblasts exposed to various UN concentrations (0.1, 1, 10, and 100 microM) in vitro. Cell proliferation was quantified by means of the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, ROS was determined using the nitro blue tetrazolium test, apoptosis was morphologically determined using Hoechst 3332 and APh activity was assayed spectrophotometrically. Electron microscopy revealed that the ultrastructure of active and inactive osteoblasts exposed to uranium presented cytoplasmic and nuclear alterations. In vitro, 1-100 microM UN failed to modify cell proliferation ratio and to induce apoptosis. ROS generation increased in a dose-dependent manner in all tested doses. APh activity was found to decrease in 1-100 microM UN-treated cells vs. controls. Our results show that UN modifies osteoblast cell metabolism by increasing ROS generation and reducing APh activity, suggesting that ROS may play a more complex role in cell physiology than simply causing oxidative damage.

Alkaline Phosphatase↗

PubMed2005

Effect of ethane-1-hydroxy-1,1-bisphosphonate (EHBP) on endochondral ossification lesions induced by a lethal oral dose of uranyl nitrate.

A 350 mg/kg body weight (b.w.) oral dose of uranyl nitrate (UN) caused 100% mortality in mice three days after administration, due to resulting kidney lesions. Mortality decreased 50% after an oral (o) or subcutaneous (sc) dose of bisodic etidronate (EHBP). Given that bone is also a target organ for uranium (U) in acute intoxication, the aim of this work was to study the effect of exposure to a lethal oral dose of UN on endochondral ossification, and the latter's response to EHBP treatment. One hundred male Balb/c mice weighing 25 g were assigned to one of ten groups. Group I served as control. Group II received a lethal 350 mg/kg b.w. oral dose of UN by gavage. Groups III, IV, VII, and VIII received an equal dose of UN immediately followed by a single 500 mg/kg oral dose of EHBP in groups III and VII and a single 50 mg/kg subcutaneous dose of EHBP in groups IV and VIII. Groups V and IX only received a single 500 mg/kg oral dose of EHBP, and groups VI and X received a single 50 mg/kg subcutaneous dose of EHBP. The animals in groups II, III, IV, V, and VI were sacrificed 48 h after the onset of the experiment, whereas those in groups VII, VIII, IX, and X were killed at 14 days. Histologic and histomorphometric studies were performed on the femurs to determine growth cartilage width, bone volume, and metaphyseal bone activity. Our results showed that all growth cartilage and metaphyseal bone histomorphometric parameters were significantly lower in animals exposed to UN at 48 h than in controls. EHPB administration was found to prevent this condition at 48 h reaching similar values to those of controls. Although histomorphometric values did not reach control values at 14 days, they were higher than those of animals exposed to UN at 48 h not treated with EHBP. It is noteworthy that these values also decreased in animals only receiving EHBP at 14 days. Our results show that EHBP effectively ameliorates the adverse effects of a lethal dose of UN on endochondral ossification.

Administration, Oral↗

PubMed2004

Biodistribution of p-borophenylalanine (BPA) in dogs with spontaneous undifferentiated thyroid carcinoma (UTC).

Human undifferentiated thyroid carcinoma (UTC) is a very aggressive tumor which lacks an adequate treatment. The UTC human cell line ARO has a selective uptake of BPA in vitro and after transplanting into nude mice. Applications of boron neutron capture therapy (BNCT) to mice showed a 100% control of growth and a 50% histological cure of tumors with an initial volume of 50 mm(3) or less. As a further step towards the potential application in humans we have performed the present studies. Four dogs with diagnosis of spontaneous UTC were studied. A BPA-fructose solution was infused during 60 min and dogs were submitted to thyroidectomy. Samples of blood and from different areas of the tumors (and in one dog from normal thyroid) were obtained and the boron was determined by ICP-OES. Selective BPA uptake by the tumor was found in all animals, the tumor/blood ratios ranged between 2.02 and 3.76, while the tumor/normal thyroid ratio was 6.78. Individual samples had tumor/blood ratios between 8.36 and 0.33. These ratios were related to the two histological patterns observed: homogeneous and heterogeneous tumors. We confirm the selective uptake of BPA by spontaneous UTC in dogs and plan to apply BNCT in the future.

Animals↗

PubMed2003

Renal function in mice poisoned with oral uranium and treated with ethane-1-hydroxy-1,1-bisphosphonate (EHBP).

Exposure to uranium is a risk for the workers involved in uranium mining, purification, and manufacture, principally by its ingestion or inhalation. It is also a risk for the population at large in case of intake of contaminated water or food. Uranium induces nephropathy that is characteristic of heavy metals, which can lead to death. The toxic effects of uranium can be prevented by a biphosphonate, ethane-1-hydroxy-1,1-bisphosphonate (bisodic etidronate), administered orally or subcutaneously. Employing bisodic etidronate, our laboratory obtained satisfactory results in terms of survival in adult mice, adult rats, and suckling rats. The aim of the present study was to evaluate the efficacy of bisodic etidronate for preventing renal dysfunction induced by a lethal dose of uranyl nitrate, employing serum levels of urea and creatinine as end-points. Two experiments were performed over different time periods, i.e., Experiment A: 48 h, Experiment B: 14 d. Each experiment was performed with 4 groups of 20 male Balb/c mice each, 25 g average body weight. Three of these groups received 350 mg kg(-1) of body weight of uranyl nitrate by gavage (forced oral administration). Two of the three exposed groups were treated with bisodic etidronate either by gavage in a dose of 500 mg kg(-1) body weight or with a subcutaneous injection of 50 mg kg(-1) body weight. The fourth group served as control. Survivors of the experimental groups were sacrificed at the end of the experiment by overdose of inhalation anesthetic (ether). The kidneys were routinely processed for histological analysis. Blood samples were taken by cardiac puncture to assess urea and creatinine serum levels. Urea and creatinine serum levels were markedly lower at 48 h in exposed animals treated with bisodic etidronate than in untreated exposed animals. On day 14 these values in exposed and treated animals did not differ significantly from control values. The renal function of animals treated with orally or subcutaneous bisodic etidronate that survived uranyl nitrate exposure was markedly improved compared to the controls of untreated exposed animals at 48 h. At 14 days, treatment with bisodic etidronate averted renal damage. At this time, the histologic study of kidneys showed images of tissue recovery. These results suggest that the use of EHBP may be of great value in reducing the renal damage.

Administration, Cutaneous↗

PubMed2003

A quantitative method to evaluate corrosion products in tissues.

The use of odontological or orthopedic metal implants requires the availability of techniques to estimate tissue response to the corrosion processes. In previous experimental studies we showed the deposition of corrosion products not only locally (Olmedo et al., Implant Dent 2003; 12: 75-80) but also systemically (Olmedo et al., J Mater Sci: Mater in Medic 2002; 13: 793-796) in organs such as liver, spleen and lung. The aim of the present study was to propose a method to quantitatively assess the tissue deposits of the corrosion products of the materials used to manufacture implants. The samples (liver and lung) were embedded in paraffin, and the histological sections were submitted to thickness standardization. The quantitative evaluation of the deposits was performed in an MPM-800 (Carl Zeiss)* microscope. The light microscopy images were digitalized and then analyzed employing the DNA-IBAS-Kontron software that allows for the identification and evaluation of cells loaded with corrosion products (objective 20x). The following end-points were assessed: total field area, number of deposits of corrosion products, partial and total area of the deposits, and the ratio between volume of the deposits and tissue volume. The method proposed serves to quantitatively evaluate, at light microscopy level, the deposition of corrosion products in tissues.

Animals↗

PubMed2002

Selective uptake of p-borophenylalanine by undifferentiated thyroid carcinoma for boron neutron capture therapy.

Undifferentiated thyroid carcinoma (UTC) lacks an effective treatment. Boron neutron capture therapy (BNCT) is based on the selective uptake of 10B-boronated compounds by some tumors, followed by irradiation with an appropriate neutron beam. The radioactive boron originated (11B) decays releasing 7Li, gamma rays and alpha particles, and these latter will destroy the tumor. In order to explore the possibility of applying BNCT to UTC we have studied the biodistribution of BPA. In in vitro studies, the uptake of p-10borophenylalanine (BPA) by the UTC cell line ARO, primary cultures of normal bovine thyroid cells (BT), and human follicular adenoma (FA) thyroid was studied. No difference in BPA uptake was observed between proliferating and quiescent ARO cells. The uptake by quiescent ARO, BT, and FA showed that the ARO/BT and ARO/FA ratios were 4 and 5, respectively (p < 0.001). In in vivo studies, ARO cells were transplanted into the scapular region of NIH nude mice, and after 2 weeks BPA (350 or 600 mg/kg body weight) was injected intraperitoneally. The animals were sacrificed between 30 and 150 minutes after the injection. With 350 mg, tumor uptake was highest after 60 minutes and the tumor/normal thyroid and tumor/blood ratios were 3 and 5, respectively. When 600 mg/kg body weight BPA were administered, after 90 minutes the tumor/blood, tumor/normal thyroid, and tumor/distal skin ratios for 10B concentrations per gram of tissue were approximately 3, showing a selective uptake by the tumor. The present experimental results open the possibility of applying BNCT for the treatment of UTC.

Adenoma↗

PubMed2002

Use of correction procedures in ploidy analysis of oral carcinomas.

Ploidy analysis is an aid in the diagnosis and evaluation of prognosis of tumors. Image analysis is a relatively simple technique to assess ploidy that can be carried out with accessible equipment. However, it requires the use of accurate technical procedures to avoid methodological errors that may bias the measurements. We previously developed two procedures that are simple to apply in routine work and serve to correct the errors derived from the measurement of large nuclei that are not fully contained in the thickness of the section and those derived from non-specific background readings. In the present study we applied these corrections to the retrospective ploidy analysis of a series of 67 patients with oral carcinoma with a follow-up time of 18 months. Thirty-four patients were alive at the end of the study, 33 were deceased. The ploidy values and the malignancy indices corresponding to the deceased and live patients with TNM stage III and IV carcinomas at the time of biopsy were significantly different. There were no significant differences in ploidy values between live and deceased patients with TNM stage I and II at the time of biopsy. The corrections improved the sensitivity of the method and thus the statistical significance of the data. These data suggest that the method proposed may be of use to estimate lesion evolution, in particular in patients with advanced oral squamous cell carcinomas.

Analysis of Variance↗

PubMed2002

Role of crevice in the occurrence of hemoglobin in saliva.

The aim of the present study was to analyze the role of the gingival-periodontal component in the presence of blood in saliva. We studied a population of 184 adult patients composed of 101 totally edentulous patients with no oral mucosa lesions and 83 dentulous patients with clinically healthy gums. Saliva samples obtained by spontaneous salivation were collected in sterile containers. Qualitative and quantitative evaluation of each of the samples was performed. 67% of the dentulous patients tested positive for hemoglobin in saliva. None of the patients in the totally edentulous group exhibited hemoglobin in saliva. These data suggest that the periodontal condition is an essential factor for the presence of hemoglobin in saliva.

Adolescent↗

PubMed2001

Effect of total body irradiation on peri-implant tissue reaction: an experimental study.

The aim of the present study was to evaluate the osseointegration process under total body irradiation conditions (LD 50/30). Twenty Wistar rats (mean body weight: 90 g) were used. Under ethyl urethane intraperitoneal anesthesia (1 g/kg body weight), the animals were irradiated with a single 700 cGy dose (linear accelerator 6 Mev photons). Four days post irradiation, a titanium laminar implant was placed in the left tibia of each rat. Antibiotic therapy (ceftriaxone) was administered daily post implantation, to prevent infection by radiation. Fourteen days post implantation, the animals were killed by ether overdose. The tibiae were resected, radiographed and processed for embedding in methyl methacrylate. The results showed impaired osteogenesis and absence of osseointegration in experimental tibiae. This could be due to a direct action of total body irradiation on osteogenesis precursor cells. This effect would impair bone formation involved in peri-implant osseointegration processes in this experimental model.

Animals↗

PubMed2001

Commercial diet induced hypothyroidism due to high iodine. A histological and radiological analysis.

A number of puppies of the School Hospital of the Faculty of Veterinary Science-UBA showed bone changes. Measurement of the iodine content of the commercial diet showed a significant increase in its content. Iodine excess causes alterations in thyroid function and morphology, and its hormones have a direct action on bone formation. Three groups of puppies were fed on different diets: a home-prepared diet, a commercial diet (containing 5.6 mg potassium iodide/kg dry food), and a home-prepared diet supplemented with 5.6 mg potassium iodide/kg dry food. Groups B and C developed hypothyroidism. A significant decrease (p<0.05) in the styloid apophyseal surface was found in groups B and C vs. A, determined by radiography. Histologically, the hypertrophied cartilage was shorter in groups B and C than in group A (p<0.0001). The present results suggest that commercial diets with a high iodine content may cause hypothyroidism and changes in bone metabolism.

Animal Feed↗

PubMed2001

An experimental model to study intrusive forces in rats.

We have developed an experimental model for the study of the response of the periodontal ligament and bone to intrusive orthodontics forces in rats. Thirty-five Wistar rats, body weight 250 gr., were grouped as follows: control (GI), 48 hs (GII), 96 hs (GIII), 7 days (GIV). A steel band was cemented to the first upper right molar with a welded spring running to the occlusal surface of the second molar to exert a vertical force of 15 gr. The left side of treated animals was also used as control. The animals were sacrificed at the corresponding treatment times. Radiographs of the left and right halves of the jawbones were taken with an ultrafine grain industrial film. Seven measurements of the width of the periodontal ligament were taken. The data reveal narrowing of the periodontal ligament at the peri-apex and the furcation area for the animals in Group II. Conversely, Group III and IV animals exhibited widening of the periodontal ligament, particularly in the animals submitted to the force for 7 days. Statistical analysis of the data by Student's paired t test showed that the difference for the latter group was statistically significant (p < 0.05). The data for the horizontal measurements do not afford conclusive results. The present results confirm the value of the model to study the response to vertical intrusive forces.

Alveolar Process↗

PubMed2000

Percutaneous toxicity of uranyl nitrate: its effect in terms of exposure area and time.

Different groups have undertaken research work focusing their attention on the biological effects of uranium and have described kidney and bone to be the main target organs in uranium poisoning. In this study we used the skin as the route of entry of uranium. We carried out two sets of experiments in adult rats: in one of them topical applications with uranyl nitrate (UN) over different areas were performed; in the other topical applications with UN on a given area over different times were carried out. In the latter experiment the exposure to UN was stopped by removing it from skin with soap and water. Kidney and bone samples were removed for histological studies. This work is based on the determination of the survival rate of the exposed animals and on the effects elicited in kidney and bone. There is a relation between the area of the surface exposed to uranium and the time of exposure and the subsequent percutaneous toxicity. There were no surviving animals following topical application of UN to an 8 cm2 area nor when the time of exposure was 24 h. The survival rate of the animals increased when either the topical area or the time of exposure to UN was reduced. Although the inhibition of bone formation in metaphysical bone has been previously described by our group as a result of UN poisoning, this is the first time that such an effect is found after percutaneous exposure for such short periods of time. The general toxic effects of UN, evidenced as kidney histological alterations, increased in severity as either one of the two variables studied increased. This is a condition that could be considered as hazardous for those workers engaged in uranium processing and purification. It is noteworthy that a simple method such as washing with soap and water is an effective method to reduce the lethality of UN percutaneous intoxication.

Administration, Topical↗

PubMed2000

Orally administered ethane-1-hydroxy-1,1-biphosphonate reduces the lethal effect of oral uranium poisoning.

Intoxication with uranium compounds is both an occupational risk for the workers engaged in the different processes of the elaboration of nuclear fuel and a risk for the population at large in terms of contaminated water and food. The toxic effects of uranium can be reduced by the administration of a biphosphonate, ethane-1-hydroxy-1,1-biphosphonate (EHBP), subcutaneously or intraperitoneally. The aim of the present work was to examine whether orally administered EHBP reduces the lethal effect of a single orally administered toxic dose of uranyl nitrate. Nine groups of 20 male Balb-c mice were used. Five groups received 350 mg kg(-1) of uranyl nitrate orally administered by gavage, four were co-treated 20 min later with EHBP either by gavage (350, 500, or 700 mg kg(-1)) or by subcutaneous injection (50 mg kg(-1)), and one group was not treated. Four groups of animals received only EHBP in doses and routes the same as those used in the intoxicated animals. Survival was assessed for 14 d. On day 14 the surviving animals of all groups were killed. An additional group of uranium intoxicated animals was killed on day 2 after the start of the experiment. Kidneys were examined histologically. On day 3 all the animals treated with uranyl nitrate alone and 20% of the animals treated with 700 mg kg(-1) of EHBP alone were dead. Survival at day 14 of the groups of mice intoxicated with uranyl nitrate and treated with EHBP (50 mg kg(-1) orally or 50 mg kg(-1) subcutaneously) was 45.0 and 49.6%, respectively. Tubule necrosis lesions were present in kidneys of mice intoxicated with uranyl nitrate, whereas lesions were less severe in mice treated with EHBP. Oral administration of EHBP is effective for reducing the lethal effect of uranium, and it is at least as useful as subcutaneous administration for prompt therapy of oral uranium exposure, achieving a survival rate of almost 50%.

Administration, Oral↗

PubMed2000

AgNOR are sensitive markers of radiation lesions in squamous epithelia.

The possibility of detection of incipient cellular alterations is central to early diagnosis and to clinician's capacity to discriminate between samples that appear similar on routine preparations. We examined the value of silver-stained nucleolar organizer regions (AgNOR) in detecting radio-induced alterations in a model of squamous epithelium biologically similar to oral mucosa. Morphometry of AgNOR has been proven to be of value in the detection of incipient cellular alterations. This method allows for the quantitative evaluation of lesions induced by high doses of radiation long before they become apparent in routine preparations. We herein examine the capacity of AgNOR to reveal the response to low doses of radiation, closer to the therapeutic or accidental dose to which the epithelium of oral mucosa may be exposed.

Analysis of Variance↗

PubMed2000

Effects of uranium poisoning on cultured preimplantation embryos.

The toxic effect of uranium in cultured preimplantation embryos of the mouse is presented. Embryos were obtained from hybrid females CBA x C57 BL following induction of superovulation and were incubated in M16 cultured medium. Two different experiments were performed. In one, embryos in a one-cell stage were placed in culture media with final concentrations of uranyl nitrate of 104 and 208 microg/mL during 120 h in the same dish. In the other experiment, embryos in a one-cell stage were placed in culture medium with uranyl nitrate with final U concentrations of 26, 52, 104, and 208 microg/mL. At 24 h, those embryos which had reached the two-cell stage were transferred to another culture dish to which fresh solutions with uranyl nitrate were added. The percentage of embryos in two-cell stage, morula, early blastocyst, expanded blastocyst, and hatched blastocyst were recorded at 24, 72, 96 and 120 h of culture. The results obtained showed that concentrations as from 26 microg U/mL induced the delay of embryo development and the impairment of blastomere proliferation. The toxic effect of uranium increased in those experiments in which the embryos were transferred to a new medium. This embryo-culture system appears to be appropriate to evaluate the toxic effect of uranium on embryos removed from maternal influences and represents a suitable test system for environmental pollutants.

Animals↗

PubMed2000

Automated image analysis for monitoring oxidative burst in macrophages.

OBJECTIVE: To evaluate oxidative bursts induced by phorbol myristate acetate in phagocytes at the single-cell level by automated image analysis. STUDY DESIGN: The generation of reactive oxygen species was quantitatively expressed by means of histograms displaying the percentage of cells corresponding to each of the total optical densities measured. RESULTS: Macrophage subpopulations were quantitatively defined. This method allows detailed analysis of the amount of formazan per cell and the sites of deposition of blue precipitate in each cell. CONCLUSION: Image analysis is a reliable quantitative, single-cell assay for studying various cellular characteristics associated with macrophage functions.

Animals↗

PubMed2000

Enlargement of periosteocytic lacunae associated to mechanical forces.

Demineralization of bone has been linked to the action of osteocytes via the process of osteocytic osteolysis. The aim of this study was to assess the influence of mechanical forces produced during orthodontic movements on the osteocytic lacunae. Orthodontic movements were achieved employing a device constructed "ad hoc" for rats that exerts a force of approximately 70 gr. The experimental animals and the corresponding controls were killed 48 and 96 hours after the onset of the experiment. Histologic sections oriented along the bucco-palatine axis were employed to measure the area of osteocytic lacunae to infer information on volume in keeping with standard stereological concepts. Regions alongside resorption areas of cortical bone and resting areas of palatine bone were evaluated. Osteocytic lacunae associated to erosive surfaces were rounded and rose markedly in area after the application of the orthodontic force (58.4 +/- 6 mm2). Elongated lacunae were present in relation to resting areas (24.8 +/- 2 mm2). The present study shows an association between the increase in size of osteocytic lacunae and the resorption fronts induced by the application of orthodontic forces. This finding would suggest that the osteocyte would participate in the resorption process of bone submitted to pressure.

Alveolar Bone Loss↗

PubMed1999

Role of distinct subpopulations of peritoneal macrophages in the regulation of reactive oxygen species release.

It has been reported in vitro that during the respiratory burst of phagocytic cells the superoxide anion production per cell shows a negative relation with the cell density. This process has been described as autoregulation. The aim of this work was to analyze the superoxide anion production in thioglycollate-elicited peritoneal macrophage exudates to evaluate the importance of the peritoneal cavity environment in the autoregulation process. 12-O-tetradecanoylphorbol-13-acetate (PMA) was used to stimulate the respiratory burst and superoxide anion production was measured evaluating the intracellular formazan deposits that precipitate as a result of nitro blue tetrazolium (NBT) reduction. We have demonstrated a negative correlation between superoxide anion production and cell density in the peritoneal cavity in macrophages challenged with PMA. The response of individual cells was analyzed by means of an image analyzer, measuring the amount of formazan per cell and cell-size changes during the process of activation. The results revealed that the decrease in individual cell response as a function of higher cell densities were due to a significant increase in the amount of basal reaction macrophages. Concomitantly, the number of reactive cells remained unchanged irrespective of the cell density of the population. A direct correlation between cell size and superoxide anion production was observed. This phenomenon was demonstrated in SENCAR and Balb/c strains. However, macrophages from SENCAR mice showed greater superoxide anion production than those from Balb/c. The differences between strains could be associated to the increased sensitivity to PMA tumor promotion of SENCAR mice. Based on this property, macrophages from SENCAR mice were stimulated with opsonized zymosan, a particulate stimulus that reflects the interaction macrophage-microorganism during the phagocytic process. This data will contribute to the knowledge of infection control. We conclude that variations in basal reaction cells modulates the macrophage activation response when excess macrophages are recruited to the peritoneum. This is demonstrated using different stimuli, thus suggesting that this response may be applied to a wide variety of stimuli-macrophage interactions. The differences between strains may be associated to the increased sensitivity to PMA tumor promotion of SENCAR mice.

Animals↗