Paulo Cesar Silva

Uso de animais em cirurgia experimental

Diversos aspectos da cirurgia experimental sao ignorados pelos pesquisadores. Este artigo enfatiza padroes eticos, detalhes anatomicos e procedimentos anestesicos com o objetivo de auxiliar na escolha adequada de animais utilizados em laboratorio para pesquisas em cirurgia e na educacao medica.

Anesthetic experimental device for small animal

PURPOSE The difficulty to anesthetize small laboratory animals with vaporizer prompted us to go in search of new materials, and create new techniques. The improved equipment of anesthesia we looked for should be low cost, practical, versatile, and its management serve ethical, teaching, and research purposes. METHODS The new components of the equipment were: the vaporizer, the unidirectional valve, the glass cylinder filled with water, the flow guidance y-shape tube, the flow regulators, the mask modifications, and another free airway for emergency occurrence. A test was done with 30 Wistar rats, Rattus norvegicus albinus, divided into three groups with 10 rats for each one. Groups 1, 2 and 3 were anesthetized with Ether, Halothane and Sevoflurane respectively, using the new gadget. The anesthetic induction time, the breathing rhythm alteration during an anesthesia pre-established time (10 minutes), and the recovery time were observed. RESULTS The equipment enabled an easy handling, and fulfilled a larger safeness and stability during the induction and anesthetic management. The test showed it was possible to make use of several anesthetic agents. CONCLUSION The device is effective, and turns the anesthesia procedure into a very easy practice with low-cost. It should be recommended for experimental surgery, teaching and research.

AN EXPEDITIOUS SYNTHESIS OF 3-NITROPROPIONIC ACID AND ITS ETHYL AND METHYL ESTERS

The synthesis to 3-nitropropionic acid 1 was easily accomplished, in two steps, from commercially available acrolein in 60% yield. The ethyl and methyl esters of 1 were also obtained.

Modelo cirúrgico de insuficiência renal crônica: estudo em coelhos

OBJECTIVES To establish a model of chronic renal failure in rabbits, with perspectives of its use for therapeutic and repairing actions. METHODS Nineteen males, adults rabbits (New Zealand) randomly distributed into three groups were used: Group 1 - Control (n =5); Group 2-Sham (n =7); and Group 3 - Experimental (n =7). They were anaesthetized by using intramuscular Cetamine, Diazepam and Fentanyl followed by Sevorane with vaporizer device. In Group 3, a bipolar left nephrectomy was carried out and after four weeks, it was also done a right nephrectomy. All the samples of the renal tissue were weighed. The Group 2 was only submitted to both abdominal laparotomies, without nephrectomy. Biochemical evaluations, with urea, creatinina, sodium and potassium measurement; abdominal ultrasound scan; scintigraphy and histological analysis were performed in all animals. RESULTS In group 3 there was a progressive increase of urea (p=0.0001), creatinine (p=0.0001), sodium (p = 0,0002) and potassium (p=0,0003). The comparison of these results with those one of the Groups 1 and 2, in all intervals, revealed blood rising with statistical significant level (p < 0,05). In Group 3, the ultrasound scan identified an increasing of the left kidney size, after 16 weeks and at the 4th week the scintigraphy confirmed the loss of 75% of the left renal mass. In the same group, the histological evaluation showed subcapsular and intersticial fibrosis and also tubular regeneration. CONCLUSION The experimental model of IRC is feasible, with animals survival in middle term which allows the use of this interval like a therapeutic window for testing different approaches in order to repair the kidney damages.

Heterologous mesenchymal stem cells successfully treat femoral pseudarthrosis in rats.

BackgroundThis study evaluated the effectiveness of treating pseudarthrosis in rats by using bone marrow cell suspensions or cultures of bone marrow mesenchymal stromal cellsMethodsThirty-eight specific pathogen-free (SPF) animals were randomly assigned to four groups: Group 1, Control, without surgical intervention; Group 2 (Placebo), experimental model of femoral pseudarthrosis treated only with saline solution; Group 3, experimental model of femoral pseudarthrosis treated with heterologous bone marrow cells suspension; Group 4, experimental model of femoral pseudarthrosis treated with cultures of heterologous mesenchymal stromal cells from bone marrow. When pseudarthrosis was confirmed by simple radiological studies, digital radiography and histopathology after a 120-day postoperative period, Groups 2, 3 and 4 were treated as above. At 30, 60 and 90 days after the treatment, all animals were evaluated by simple radiological studies, and at the end of the experiment, the animals were assessed by computed axial tomography and anatomopathological and histomorphometric examinations.ResultsInjected cells were detected in the areas affected by pseudarthrosis using scintigraphy within the first 24 hours after their administration. After 60 days, the animals of Group 3 showed callus formation while the animals of Group 4 presented periosteal reaction and had some consolidated areas. In contrast, Group 2 showed a predominance of fibro-osteoid tissue. After 90 days, bone consolidation and remodeling was observed in all animals from Group 3 whereas animals from Group 4 exhibited partial consolidation and those ones from Group 2 persisted with pseudarthrosis.ConclusionThe treatment with heterologous bone marrow cells suspension proved to be effective in the treatment of pseudarthrosis whereas cultures of heterologous bone marrow mesenchymal stromal cells did not show the same potential to aid bone healing.

Molars extraction for bone graft study in rabbits

PURPOSE The aim of this study was to describe an experimental surgical technique to be used in the evaluation of bone grafts in rabbits. METHODS The operative technique was performed in jaws, with external approach from the labial commissure to the last molar tooth. An incision about 1cm extended forward to the alveolar ridge, followed by a exposing the cervical region of the alveolar bone and dental elements was done. Thus, after extraction of first molar with forceps, the tooth socket left was filled with hydroxyapatite. The bone gain was analyzed by histopathological studies. RESULTS The histological analyses indicated formed bone surrounding the biomaterial. CONCLUSION The experimental model using the tooth socket of the rabbit molar is a feasible procedure for studies of bone grafts.

Development of blood vessels of the greater omentum in the hepatic lobe after vascular ligation: an experimental model in the rats

PURPOSE To verify the development of blood vessels between the greater omentum and the liver in the presence of distinct liver blood intake blockages. METHODS Two hundred and eighty conventional male Wistar rats were used, divided into 5 groups: control (n=35), laparotomy (n=35); hepatic artery ligature (n=70), ligature of the right-hand branch of the portal vein (n=70); and ligature of both blood vessels (n=70). The last three groups were divided into two subgroups each (n=35), according to the presence or absence of the transposition of the greater omentum onto the right hepatic lobe. The postoperative periods were 1, 3, 7, 15, 30, 60 and 90 days. At the end of each period, the greater omentum and right hepatic lobe were collected for histopathological examination. The presence of blood vessels between the referred tissues was verified by the administration of Indian ink as a marker of vascular lumen. RESULTS Macroscopic and microscopic observation and the dye marker demonstrated the distribution of blood vessels between the greater omentum and liver tissues. CONCLUSION The greater omentum was capable of developing blood vessels when fixed to the parenchyma of the liver after the suppression of hepatic blood flow.

50 MHz ultrasound characterization of colitis on rats, in vitro

Ultrasound (50 MHz) was used for in vitro characterization of trinitrobenzene sulfonic acid-induced colitis on rats. Images and wave propagation parameters were obtained for colitis (n=38). Mean (plusmn2 se) results are: 1624.90(plusmn20.21) mmiddots-1 for speed of sound; 5.12(plusmn0.30) dBmiddotmm-1 for attenuation coefficient; 3.26(plusmn1.03)times10-3 (srmiddotmm)-1 for backscattering coefficient and 1.63 (plusmn0.10) for frequency dependence. Integrated backscattering coefficient (IBC), measured across the colon wall (n=4), ranges from 10-3 to 10-2 (srmiddotmm)-1, with the highest IBC values found in the submucosa layer. The result for speed of sound is similar to that of human sclera found in the literature. Results for attenuation and backscattering coefficients are in the same range of literature reports for human sclera and ciliary muscle, respectively. IBC plots allowed for ultrasound scattering quantification of the mucosa, submucosa and muscular layers for TNBS colitis.

Exogenous pulmonary surfactant prevents the development of intra-abdominal adhesions in rats.

Intra‐abdominal adhesions are major post‐operative complications for which no effective means of prevention is available. We aimed to evaluate the efficacy of exogenous pulmonary surfactant administration in the prevention of post‐operative abdominal adhesions. Rats were randomly assigned to undergo laparotomy (L) or gastroenterostomy (GE) and then treated with surfactant (groups L‐S and GE‐S, respectively). Intra‐abdominal adhesions, collagen fibre content, metalloproteinase (MMP)‐9, expression of growth factors (TGF‐β, KGF and VEGF), type III procollagen (PCIII) and pro‐caspase 3, as well as isolectin B4 and ED1‐positive cells expressing MMP‐9, were evaluated. Groups treated with surfactant (GE‐S and L‐S) exhibited fewer adhesions. A significant reduction in collagen fibre content was observed in GE‐S compared to GE animals (P < 0.001). In situ and gelatin zymography analysis showed higher MMP‐9 expression and activity in the GE‐S group compared to the GE group (P < 0.05). ED1‐positive cell counts were significantly higher in the GE‐S group (P < 0.001) than in the GE group. Virtually all cells positive for ED1 were MMP‐9+. Double‐labelling of MMP‐9 with IB4 showed no significant differences between GE‐S and GE groups. TGF‐β, KGF, PCIII and pro‐caspase‐3 mRNA expression decreased significantly in GE‐S compared to GE animals (P < 0.05). Surfactant administration also reduced apoptosis in the GE‐S group. These findings suggest that surfactant reduces the intra‐abdominal adhesions triggered by laparotomy and gastrointestinal anastomosis, thus preventing fibrosis formation at the peritoneal surfaces. This preclinical study suggests an innovative treatment strategy for intra‐abdominal adhesions with surfactant and to endorse its putative mechanism of action.

In-vivo bone response to titanium screw implants anodized in sodium sulfate

PURPOSE To evaluate the early bone response to a nanotextured dental implant treated with sodium sulfate (Na2SO4), using a rabbit model. METHODS Twelve animals were randomly divided into group 1 (Control) - machined implants and group 2 (Test) - nanotextured implants. Extra-oral incision was performed to provide access to intended surgical site where the dental implant was inserted immediately after the extraction of the mandibular first premolar. Implant surface characterization was performed by scanning electron microscopy attached to energy dispersive spectroscopy and interferometry. Three weeks after surgery, the animals were induced to death and undecalcified sections of the samples were prepared for histological and histomorphometrical analysis. RESULTS Surface characterization of the implant demonstrated enhanced surface area of anodized group compared to Control group with 19.2% ± 6.2 versus 1.6 ± 0.7, respectively. Histological evaluation demonstrated new bone formation starting from the buccal and lingual cortical walls on both groups. After three weeks, significant higher bone contact of 27% (p<0.05) was observed to nanotextured compared to machined implants (Control group). CONCLUSION The anodization with sodium sulfate nanostructures to the implant surface that resulted in faster osseointegration.