Experimental model of gastric carcinogenesis with N-methyl-N-nitrosourea for F344 rats and C3H mices is valid for Wistar rats?

Introdução: O N-metil-N-nitrosourea (MNU) tem ação cancerígena direta, induzindo tumores em várias espécies em uma variedade de órgãos, incluindo o estômago de ratos. Tratamento do MNU na água de beber por 25-42 semanas, seletivamente, induz carcinoma gástrico glandular de ratos F344 e camundongos C3H. Objetivo: Estabelecer um modelo experimental para indução seletiva de câncer no estômago glandular de ratos Wistar com MNU. Métodos: Um total de 48 ratos Wistar machos com oito semanas, foram utilizados no presente estudo. MNU (Sigma-Aldrich) foi dissolvido em DMSO e liberada água potável ad libitum por um período variando de 16 a 70 semanas. Após 16 semanas, quatro ratos foram selecionados aleatoriamente e mortos. Depois, de seis em seis semanas, quatro animais também foram mortos até 70 semanas. Resultados: A taxa de sobrevivência foi superior a 90%. Ocorreu a indução de dois adenocarcinomas, um carcinoma espinocelular e um sarcoma. A incidência de adenocarcinoma gástrico foi de 4,5% (0,5 a 15). Conclusões: O modelo experimental de carcinogênese gástrica em ratos Wistar, utilizando MNU dissolvido na água, não mostrou viabilidade prática neste estudo, devido à baixa taxa de adenocarcinoma gástrico que ocorreu.Background: The N-methyl-N-nitrosourea (MNU) is a direct acting carcinogen, inducing tumors in several species in a variety of organs, including stomach of rats. Treatment of MNU in the drinking water for 25-42 weeks selectively induced glandular gastric carcinoma in F344 rats and C3H mice. Aim: To establish an experimental model for selective MNU induction of glandular stomach cancer in Wistar rats. Methods: A total of 48 males eight-week-old Wistar rats were used in the present study. MNU (Sigma-Aldrich) was dissolved in DMSO and provided as the drinking water ad libitum for a period ranging from 16 to 70 weeks. After 16 weeks, four rats were randomly selected and killed. After every six weeks four animals were killed until 70 weeks. Results: Survival rate was higher than 90%. It had the induction of two adenocarcinomas, one squamous cell carcinoma and one sarcoma. The incidence of gastric adenocarcinoma was 4.5% (0.5 to 15). Conclusions: The experimental model of gastric carcinogenesis in Wistar rats, using MNU dissolved in water, showed not practice viability in this study due to the low rate of gastric adenocarcinoma

Liquid and Gel Platelet Rich Plasma as Skin Healing Adjuvant

Background: In recent decades, many researches have been conducted on processes involved in tissue repairing, mainly in the development of resources and technology designed to improve the wound healing progress. Platelet rich plasma (PRP) derived from autologous blood is defined as a plasma volume with platelet concentration higher than physiological level. It is an autogenous and low cost source of growth factors, which are essential for tissue regeneration due to their angiogenic, mitogenic, and chemotactic properties. The aim of this study was evaluate two forms of PRP- liquid and gel - regarding their capacity to influence quality and repair time of standardized skin injuries.Materials, Methods & Results: New Zealand healthy rabbits were distributed in three groups (n = 6): control group (CG), liquid platelet rich plasma group (LIQPRP), and gel platelet rich plasma group (GELPRP). Acute skin lesions were inducted in two areas approximately 2 cm close to scapular edge and depth including epidermis, dermis, and hypodermis to external muscular fascia. Animals received treatment according to each group. Injuries were measured with digital pachymeter in two directions: longer length (l) and longer width (w), every two days. Areas and healing rates were calculated. Microscopic analysis samples were collected on days seven and 14 and evaluated through hematoxylin and eosin staining (HE) for global tissue examination, and through Masson’s trichrome (MT) to collagen fibers present within the interstice. These analyzes considered: angiogenesis, inflammation infiltrated and collagen fibers quantity. Immunohistochemistry with anti-Ki-67 antibody was utilized for proliferative profile assessment. Kruskal-Wallis’ non-parametric tests of independent samples was performed for comparison of values obtained through platelet count, referring to evaluation of platelet increase on treatments. Scar contraction rate (CR) was evaluated through Shapiro-Wilk’s normality test, and then submitted to mixed models test. Results obtained by histopathological and immunohistochemistry were also evaluated by Shapiro-Wilk’s normality test (for all tests a 5% level of significance was considered). Platelet concentration achieved with liquid PRP was 8.64 and gel PRP reached 5.62 times higher than physiological values. Platelet increase mean for both groups was 7.95. No statistical significance was observed between groups. No side-effects or adverse reactions related to PRP usage were observed while study was conducted.Discussion: In the present study, there was a need to raise platelet poor plasma volume in order to obtain autogenous thrombin required for gel PRP. After this modification, a stable and reasonable platelet concentration gel was produced. However, this form of PRP application requires more time for sample preparation, increasing the production cost. Furthermore, injection of liquid PRP directly in the wound site activates platelets by generated substances due to needle perforation, and mainly due to tissue trauma generated at the lesion site. Relating to the therapies administered, gel PRP was considered more manageable, since 3D structure could easily adapt to wound site after simply deposition of it. Liquid PRP was administered with needle and syringe, which required the surgeon to be more careful and perform a slow injection in order to avoid any spill and loss of material. Furthermore, histopathological analysis did not point any clot traces formed by gel PRP dehydration, although it is not possible to ensure that the clot was eliminated, reabsorbed, or even removed by the animal. By this protocol, a stable and reasonable platelet concentration gel was produced. Further studies are encouraged as well as employment of alternative diagnostic tools, in order to better understand found results

Experimental model of gastric carcinogenesis with N-methyl-N-nitrosourea for F344 rats and C3H mices is valid for Wistar rats?

Introdução: O N-metil-N-nitrosourea (MNU) tem ação cancerígena direta, induzindo tumores em várias espécies em uma variedade de órgãos, incluindo o estômago de ratos. Tratamento do MNU na água de beber por 25-42 semanas, seletivamente, induz carcinoma gástrico glandular de ratos F344 e camundongos C3H. Objetivo: Estabelecer um modelo experimental para indução seletiva de câncer no estômago glandular de ratos Wistar com MNU. Métodos: Um total de 48 ratos Wistar machos com oito semanas, foram utilizados no presente estudo. MNU (Sigma-Aldrich) foi dissolvido em DMSO e liberada água potável ad libitum por um período variando de 16 a 70 semanas. Após 16 semanas, quatro ratos foram selecionados aleatoriamente e mortos. Depois, de seis em seis semanas, quatro animais também foram mortos até 70 semanas. Resultados: A taxa de sobrevivência foi superior a 90%. Ocorreu a indução de dois adenocarcinomas, um carcinoma espinocelular e um sarcoma. A incidência de adenocarcinoma gástrico foi de 4,5% (0,5 a 15). Conclusões: O modelo experimental de carcinogênese gástrica em ratos Wistar, utilizando MNU dissolvido na água, não mostrou viabilidade prática neste estudo, devido à baixa taxa de adenocarcinoma gástrico que ocorreu.Background: The N-methyl-N-nitrosourea (MNU) is a direct acting carcinogen, inducing tumors in several species in a variety of organs, including stomach of rats. Treatment of MNU in the drinking water for 25-42 weeks selectively induced glandular gastric carcinoma in F344 rats and C3H mice. Aim: To establish an experimental model for selective MNU induction of glandular stomach cancer in Wistar rats. Methods: A total of 48 males eight-week-old Wistar rats were used in the present study. MNU (Sigma-Aldrich) was dissolved in DMSO and provided as the drinking water ad libitum for a period ranging from 16 to 70 weeks. After 16 weeks, four rats were randomly selected and killed. After every six weeks four animals were killed until 70 weeks. Results: Survival rate was higher than 90%. It had the induction of two adenocarcinomas, one squamous cell carcinoma and one sarcoma. The incidence of gastric adenocarcinoma was 4.5% (0.5 to 15). Conclusions: The experimental model of gastric carcinogenesis in Wistar rats, using MNU dissolved in water, showed not practice viability in this study due to the low rate of gastric adenocarcinoma

敏感性分析在毛豬飼料研究上之應用

本篇論文之目的在於將線型規劃之敏感性分析應用到毛豬飼料之研究上。希望在求出最佳飼料配方之外，還能提出一些更有價值之資訊供毛豬業者及飼料業者參考。第壹章 導論一、研究動機與目的。二、研究方法與資料來源。三、研究限制。第貳章 敏感性分析之理論探討。一、線型規劃「單純法」概述。二、Zj----Cj之含意。三、目標函數係數之變動。四、右手資源常數之變動。五、影價格之分析。第□章 實例應用－－毛豬飼料之研究一、有關資料。二、線型規劃求解。三、單味飼料價格之變動及其含意。四、營養成分要求之變動及其含意。五、影價格之分析及其含意。第肆章 結論一、最佳飼料配方。二、主要單味飼料之代替性。三、主要營養成分之代替性。四、其他建議