Judul: Khasiat Antihiperurisemia Ekstrak Kulit Batang Mahoni (Swietenia macrophylla King) pada Tikus Putih Galur Sprague Dawley
Abstrak: Mahogany bark is wood industrial waste, contains flavonoid compound supposedly as antihyperurisemic agent. However, study concerning antihyperuricemic potential of mahogany bark has not been done until now. The aim of this study was to investigate the potent of mahogany bark (Swietenia macrophylla King ) extracts on serum uric acid levels in hyperuricemic rats. Thirty-three rats were divided into 5 groups of: normal, hiperurisemia (HU), allopurinol (HU I), aqueous extract (HU II), and methanol extracts (HU III). Hyperuricemic condition was induced by oral administration of 25 g/KgBW chicken liver juice with sodium carboxyl methylcellulose 0.5% mixture in rats every day for 4 weeks. This was followed by oral administration of both aqueous extract and methanol extract at 500 mg/KgBW day for 7 days. Serum uric acid levels was determined by dichlorohydroxybenzene sulfonic acid (DHBS) method on 514 nm. The induction of hyperuricemia was able to increase the serum uric acid levels 36.83%. Aqueous extract and methanol extract reduced uric acid concentration 24.22% and 21.02%, respectively. Therefore, both of the extracts have a similar antihyperuricemic effect
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Judul: Khasiat antioksidasi ekstrak kulit kayu mahoni (Swietenia macrophylla King) terhadap peroksidasi lipid pada hati tikus hiperurisemia
Abstrak: The bark of mahogany (Swietenia macrophylla King) contains bioactive compounds, which has been reported as an antioxidant. But there had been very few in vivo evidence of the antioxidant effectiveness on the liver lipid peroxidation in hyperuricemic rats. This study aimed to test the effect of mahogany (Swietenia macrophylla King) bark extracts against lipid peroxidation in hyperuricemic rat liver. Thirty three rats were divided into 5 groups, namely normal, hyperuricemic (HU), allopurinol (HU I), aqueous extract (HU II) and methanol extract (HU III). Hyperuricemic induction was carried out by giving the juices of chicken liver and sodium carboxyl methyl cellulose 0.5%. The induction was administered orally for 4 weeks with dosage of 25 g/kg BW. Afterwards, rat were administered by aqueous extract and methanol extract at 500 mg/Kg BW day for 7 days. Liver lipid peroxides analysis was determined by using thiobarbituric acid (TBA) method. The results showed that the lipid peroxide concentrations of hyperuriemic, allopurinol and methanol extracts group were 101.51 ± 54.74 nmol/gram, 108.55 ± 45, nmol/g and 101.04 ± 26.68 nmol/gram, respectively. The aqueous extract has the antioxidants effect on rat liver lipid peroxidation with the concentration of 63.57 ± 16.84 nmol/g, smaller than that of the normal group (93.83 ± 29.55 nmol/gram). Statistically, the aqueous extract tend to decrease the liver lipid peroxide concentration of hiperuricemic rat by 32.25% (p = 0.054).
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Judul: Gelombang soliter internal pada lapisan atmosfir yang memiliki perubahan kecepatan angin yang cepat
Abstrak: Gelombang internal adalah suatu gelombang yang terjadi di dalam suatu fluida. Gelombang ini muncul karena adanya perubahan rapat massa di setiap lapisan di dalam fluida. Salah satu gelombang internal yang ditemui di lapisan atmosfir adalah gelombang soliter internal, seperti yang terjadi pada fenomena "Morning glory" di Australia. Pada fenomena "Morning glory" terjadi penurunan tekanan hingga beberapa millibar. Tulisan ini membahas perambatan gelombang soliter internal pada lapisan atmosfir. Lapisan atmosfir yang ditinjau memiliki suatu lapisan dimana kecepatan angin dan rapat massanya berubah secara cepat, sedangkan lapisan lainnya relatif konstan. Persamaan gerak gelombang diturunkan berdasarkan persamaan kekontinuan dan persamaan momentum. Sedangkan metode yang digunakan adalah metode asimtotik. Solusi persamaan gerak dimisalkan dalam bentuk gelombang berjalan, dan bentuknya berupa fungsi rasional. Sebagai contoh, diberikan suatu studi kasus dimana pada suatu lapisan kecepatan angin dan rapat massanya berupa fungsi linear, sedangkan lapisan lainnya konstan.
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