Judul: Gambaran Spermatogenesis dan Superoksida Dismutase pada Testis Tikus Model Diabetes yang Diberi Ekstrak Etanol Biji Mahoni (Swietenia mahagoni Jacq.).
Abstrak: Diabetes mellitus (DM), a metabolic disease, is characterized by hyperglycemia. The aim of this study was to analyze the number of spermatogenic cells, the number of Leydig cells, and antioxidant Cu,Zn-SOD content in the testical tissues of experimental diabetic rats treated with ethanolic Swietenia mahagony seed extract. This study used 25 rats Sprague Dawley and the rats were divided into 5 groups; non DM group (K-), DM group (K+), DM group that was treated with ethanolic Swietenia mahagony seed extract (EM), DM group that was treated with acarbose 2 mg/kg body weight (KO), and non DM group that was treated with ethanolic Swietenia mahagony seed extract (KE). The dose of the extract was 500 mg/kg body weight. The treatments were done for 28 days. The testical tissues were subjected to tissue processing and stained using hematoxylin eosine and immunohistochemical technique. The results showed that ethanolic Swietenia mahagony Jacq. seed extract increased the number of spermatogenic cells, the number of Leydig cells, and antioxidant Cu,Zn-SOD content in the testical tissues of experimental DM rats.
Keyword: antioxidant, superoxide dismutase, Leydig cells, spermatogenesis, Swietenia mahagony

Judul: Aktivitas Antioksidan Ekstrak Etanol Biji Mahoni (Swietenia mahagoni Jacq.) pada jaringan Hati dan Ginjal Tikus Model Diabetes: Studi Imunohistokimia
Abstrak: Diabetes mellitus (DM) is a syndrome metabolic disease that can be indicated with high of blood glucose levels. The decreasing of carbohydrate metabolism, protein, and lipid in DM caused by deficiency and resistance of insulin. The DM condition has increased production of free radical and reactive oxygen spesies (ROS) that create a situation of known as oxidative stress, which antioxidant is lower than the amount of free radicals. As an alternative to handle oxidative stress condition, the patients of DM can consume high antioxidant plant to prevent the complication of the disease due to diabetes and to help lower of blood sugar. Any one of plant which has the antioxidant is the mahogany seeds (Swietenia mahagoni Jacq.). The mahogany seeds were conducted from the Leuwiliang, Bogor Districts, West Java. The aim of this research were to: (1) analyze the antioxidant activity of an ethanol mahogany seeds extract, (2) measure the amount of feed consumption, body weight, and blood glucose levels of diabetic rats, (3) measure of malondialdehyde levels (MDA) of the liver and kidney tissues of diabetic rats, and (4) analyze the content of antioxidant Cu,Zn-SOD of the liver and kidney tissues of diabetic rats using immunohistochemical technique. The study was used male Rattus norvegicus strain Sprague Dawley. The rats were divided into 5 groups: (i) negative control group/ non DM (K-), (ii) positive control group/ DM (K+), (iii) DM group was treated with 500 mg/kgBW of the ethanol mahogany seeds extract (EM), (iv) DM group was treated with 2 mg/kgBW of acarbose (KO), and (v) non DM group was treated with 500 mg/kgBW of the ethanol mahogany seeds extract (KE). The condition of DM was obtained by alloxan (110 mg/kgBW) induction that injected by intraperitoneal. The the measurement of blood glucose levels was used glucometer two days after alloxan induced. The blood has taken with piercing the tip of tail rats using a frank needle. Furthermore, each group has given extract treatment once a day in the morning for 28 days. The treatment has given using sonde needle. The extracts was used an ethanol mahogany seed extract macerated with 96% ethanol solvent. The weight of feed consumption was conducted every day, while the measurement of blood glucose levels and body weight of rats was conducted every four days. The weight of feed number, body weight and measurement of blood glucose levels should be done every morning before the provision of extract treatment. At the end of the treatment, the rats were anesthetized with ketamine (75 mg/kgBW) and xylazine (8 mg/kgBW). The liver and kidney tissues were conducted and analyzed for (a) the content of malondialdehyde (MDA) using thiobarbiturate acid reactive substance (TBARS) method and (b) the content of antioxidant Cu,Zn-SOD using immunohistochemical technique. The results showed that an ethanol mahogany seeds extract that macerated with 96% ethanol solvent have a weak in antioxidant activity. The DM rats that has given an ethanol mahogany seeds extract (EM) have the similiar number of feeds consumption (P>0.05) with K- group. This condition was followed by the increasing of body weight on the EM group
Keyword: diabetic experimental rats, malondialdehyde, superoxide dismutase, Swietenia mahagoni Jacq

Judul: Which one use to overcome multicollinearity ? Ridge regression or principal component regression
Abstrak: In multiple linear regression the effect of nonorthogonality of the prediction vectors is to pull the least squares estimates of the regression coefficient away from the true coefficient that one is trying to estimate. Separating the effects of each factor of the regressors has been found to be difficult because of high correlation among independent variables. Although the multicollinearity problem has been recognized by many ways, ordinary least squares is still the main technique used in many fields, but the estimation of regression coefficient can present problems when the data vectors for the predictors are not orthogonal, or in this case are multicollinear. In using ordinary least squares, the regression coefficient may be unstable, too large in absolute value, and incorrect with respect to sign. Introduced biased estimation refer to unbiased one that measure the average closeness to the parameter being estimated corresponding to its mean square error (MSE). Ridge regression and principal component can produce better estimates by its own way than those given by ordinary least squares. It may well be preferred estimator since it will have larger probability of being close to true parameter value. Two of the biased regression methods, ridge regression and principal component regression will be applied into this research and discuss briefly for each of its properties. These methods have its particular idiosyncrasy. The biased regression methods attack the collinearity problem by computationally suppressing the effects of the collinearity. Ridge regression does this correctly by modifying the correlation matrix adding a biased constant driving through nonsingular matrix. Principal component regression attacks the problem by regressing Y on the important principal component and then parceling out the effect of the principal component variables to the original variables. Finally translated back the obtained variables into original variables yield the same sign and nearly the same coefficients for both methods.
Keyword: Regresssion analysis