Chronic Carbon Tetrachloride Applications Induced Hepatocyte Apoptosis in Lipocalin 2 Null Mice Through Endoplasmic Reticulum Stress and Unfolded Protein Response.

The lack of Lipocalin (LCN2) provokes overwhelming endoplasmic reticulum (ER) stress responses in vitro and in acute toxic liver injury models, resulting in hepatocyte apoptosis. LCN2 is an acute phase protein produced in hepatocytes in response to acute liver injuries. In line with these findings we investigated ER stress responses of Lcn2-/- mice in chronic ER stress using a long-term repetitive carbon tetrachloride (CCl4) injection model. We found chronic CCl4 application to enhance ER stress and unfolded protein responses (UPR), including phosphorylation of eukaryotic initiation factor 2α (eIF2α), increased expression of binding immunoglobulin protein (BiP) and glucose-regulated protein 94 (GRP94). IRE1α/TRAF2/JNK signaling enhanced mitochondrial apoptotic pathways, and showed slightly higher in Lcn2-/- mice compared to the wild type counterparts, leading to increased hepatocyte apoptosis well evidenced by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining. Hepatocyte injuries were confirmed by significant high serum alanine transaminase (ALT) levels in CCl4-treated Lcn2-/- mice. Lcn2-/- mice furthermore developed mild hepatic steatosis, supporting our finding that ER stress promotes lipogenesis. In a previous report we demonstrated that the pharmacological agent tunicamycin (TM) induced ER stress through altered protein glycosylation and induced high amounts of C/EBP-homologous protein (CHOP), resulting in hepatocyte apoptosis. We compared TM-induced ER stress in wild type, Lcn2-/-, and Chop null (Chop-/-) primary hepatocytes and found Chop-/- hepatocytes to attenuate ER stress responses and resist ER stress-induced hepatocyte apoptosis through canonical eIF2α/GADD34 signaling, inhibiting protein synthesis. Unexpectedly, in later stages of TM incubation, Chop-/- hepatocytes resumed activation of IRE1α/JNK/c-Jun and p38/ATF2 signaling, leading to late hepatocyte apoptosis. This interesting observation indicates Chop-/- mice to be unable to absolutely prevent all types of liver injury, while LCN2 protects the hepatocytes by maintaining homeostasis under ER stress conditions.

Effect of aloe (Aloe vera Linn.) on healthy adult volunteers: changes in urinary composition.

OBJECTIVE: 1. To investigate the amount of citrate and tartrate in aloe gel, and in the urine of healthy normal volunteers, before and after consuming fresh aloe gel. 2. To evaluate the changes in the chemical composition of urine among subjects after taking aloe gel. 3. To determine the value of consuming aloe gel for prevention of renal stone formation. DESIGNS: Experimental study; before and after experiment with no control group MATERIAL AND METHOD: Thirty one healthy male medical students between 18 and 23 years of age were enrolled (with informed consent) in the clinical trial. Subjects ingested 100 g of fresh aloe gel twice a day for seven consecutive days. The 24-hr urine was collected one day prior to taking the gel (Day 0), Days 2 and 5 of consumption, and Day 8 (one day after completion). The authors determined the urine volume, osmolality, potassium, sodium, phosphate, calcium, magnesium, uric acid, citrate, tartrate, oxalate, Permissible Increment in calcium (PI in calcium), Permissible Increment in oxalate (PI in oxalate), Concentration product ratio of calcium phosphate (CPR of CaPO4) and the citrate per creatinine ratio. RESULTS: The citrate and tartrate concentration in 100 g of fresh aloe gel was 96.3 and 158.9 mg, respectively. The urinary excretion of oxalate was significantly decreased (p < 0.05). The PI in calcium was significantly increased (p < 0.05), while the citrate excretion and PI in oxalate were consistently, albeit non-significantly, increased. The mean CPR values of CaPO4 were decreased non-significantly. The other measurements were unremarkable. CONCLUSION: Fresh Aloe vera gel (100 g) contains 96.3 mg of citrate and 158.9 mg of tartrate. This is mid-range for Thai fruits. Changes in chemical compositions of urine after aloe consumption shows its potential for preventing kidney stone formation among adults.