In Vitro and In Vivo Aldose Reductase Inhibitory Activity of Standardized Extracts and the Major Constituent of Andrographis paniculata

Aldose reductase is the first enzyme in the polyol pathway and catalyzes the reduction of glucose to sorbitol by coupling with the oxidation of NADPH to NADP⁺. This sorbitol accumulation leads to various diabetic complications, including neuropathy, nephropathy, cataracts, and retinopathy. In the present study, aldose reductase inhibitory (ARI) activity of the methanolic as well as standardized extracts of Andrographis paniculata (Burm. f.) Wall. ex Nees (Acanthaceae) and its chief constituent, andrographolide, were studied using in vitro and in vivo methods. In the in vitro method, rat lens as well as kidney homogenates were used for the preparation of enzyme, whereas the effect of these test samples on the galactitol level in the eye lens was studied in a galactosemic rat model in vivo. The results of the study revealed that both extracts of the plant and its major compound, andrographolide, possess ARI activity in vitro. They were also found to significantly decrease galactitol accumulation in vivo. Copyright © 2012 John Wiley & Sons, Ltd.     

Surgical Resection for Hepatoblastoma—Updated Survival Outcomes

Background

Hepatoblastoma is the most common liver malignancy in the pediatric age group. The management of hepatoblastoma involves multidisciplinary approach.

Methods

Patients with hepatoblastoma who underwent liver resection between 2000 and 2013 were analyzed and survival outcomes were studied.

Results

The crude incidence rate of hepatoblastoma at the Madras Metropolitan Tumor Registry (MMTR) is 0.4/1,00,000 population per year. Twelve patients underwent liver resection for hepatoblastoma during the study period; this included eight males and four females. The median age at presentation was 1.75 years (Range 5 months to 3 years). The median serum AFP in the study population was 20,000 ng/ml (Range 4.5 to 1,40,000 ng/ml). Three patients had stage I, one patient had stage II, and eight patients had stage III disease as per the PRETEXT staging system. Two patients were categorized as high risk and ten patients were categorized as standard risk. Seven of these patients received two to four cycles of neoadjuvant chemotherapy (PLADO regimen), and one patient received neoadjuvant radiation up to 84 Gy. Major liver resection was performed in nine patients. Nine patients received adjuvant chemotherapy. The most common histological subtype was embryonal type. Microscopic margin was positive in three cases. One patient recurred 7 months after surgery and the site of failure was the lung. The 5-year overall survival of the case series was 91%. The median survival was 120 months.

Conclusion

Liver resections can be safely performed in pediatric populations after neoadjuvant treatment. Patients undergoing surgery had good disease control and long-term survival.

     

Defect of hepatocyte growth factor secretion by fibroblasts in idiopathic pulmonary fibrosis

Hepatocyte growth factor (HGF) is a growth factor that protects alveolar epithelial cells from pulmonary fibrosis in various animal models. We compared in vitro HGF production by human lung fibroblasts from patients with idiopathic pulmonary fibrosis (IPF, n = 8) and from control subjects (n = 6). Basal HGF secretion by IPF fibroblasts was decreased by 50% when compared with control fibroblasts (p < 0.05). HGF was secreted mainly in the cleaved mature form, both in IPF and control fibroblasts. HGF messenger RNA levels were reduced in IPF fibroblasts. Prostaglandin (PG) E2 secretion by IPF fibroblasts was low when compared with control subjects (p < 0.05). After the addition of PGE2 (10-6 M) or dibutyryl cyclic AMP (10-3 M), HGF secretion by IPF fibroblasts reached the level of control subjects. Inhibition of PGE2 synthesis with indomethacin reduced HGF secretion by control fibroblasts but had no effect on IPF fibroblasts. HGF secretion by control fibroblasts was also slightly inhibited by transforming growth factor (TGF)-beta1 and stimulated by anti-TGF-beta antibody, whereas both agents had no effect on IPF fibroblasts. Our results demonstrate a defect in HGF production by IPF fibroblasts that seems secondary to a defect in PGE2 secretion.     

Structure of lactococcal phage p2 baseplate and its mechanism of activation

Siphoviridae is the most abundant viral family on earth which infects bacteria as well as archaea. All known siphophages infecting gram+ Lactococcus lactis possess a baseplate at the tip of their tail involved in host recognition and attachment. Here, we report analysis of the p2 phage baseplate structure by X-ray crystallography and electron microscopy and propose a mechanism for the baseplate activation during attachment to the host cell. This ∼1 MDa, Escherichia coli-expressed baseplate is composed of three protein species, including six trimers of the receptor-binding protein (RBP). RBPs host-recognition domains point upwards, towards the capsid, in agreement with the electron-microscopy map of the free virion. In the presence of Ca²⁺, a cation mandatory for infection, the RBPs rotated 200° downwards, presenting their binding sites to the host, and a channel opens at the bottom of the baseplate for DNA passage. These conformational changes reveal a novel siphophage activation and host-recognition mechanism leading ultimately to DNA ejection.     

Sumoylated PPARα mediates sex-specific gene repression and protects the liver from estrogen-induced toxicity in mice

As most metabolic studies are conducted in male animals, understanding the sex specificity of the underlying molecular pathways has been broadly neglected; for example, whether PPARs elicit sex-dependent responses has not been determined. Here we show that in mice, PPARα has broad female-dependent repressive actions on hepatic genes involved in steroid metabolism and immunity. In male mice, this effect was reproduced by the administration of a synthetic PPARα ligand. Using the steroid oxysterol 7α-hydroxylase cytochrome P450 7b1 (Cyp7b1) gene as a model, we elucidated the molecular mechanism of this sex-specific PPARα-dependent repression. Initial sumoylation of the ligand-binding domain of PPARα triggered the interaction of PPARα with GA-binding protein α (GABPα) bound to the target Cyp7b1 promoter. Histone deacetylase and DNA and histone methylases were then recruited, and the adjacent Sp1-binding site and histones were methylated. These events resulted in loss of Sp1-stimulated expression and thus downregulation of Cyp7b1. Physiologically, this repression conferred on female mice protection against estrogen-induced intrahepatic cholestasis, the most common hepatic disease during pregnancy, suggesting a therapeutic target for prevention of this disease.     

Selective blockade of PGE2 EP1 receptor protects brain against experimental ischemia and excitotoxicity, and hippocampal slice cultures against oxygen-glucose deprivation

Cyclooxygenase-2 (COX-2) enzyme increases abnormally during excitotoxicity and cerebral ischemia and promotes neurotoxicity. Although COX-2 inhibitors could be beneficial, they have significant side effects. We and others have shown that the EP1 receptor is important in mediating PGE₂ toxicity. Here, we tested the hypothesis that pretreatment with a highly selective EP1 receptor antagonist, ONO-8713, would improve stroke outcome and that post-treatment would attenuate NMDA-induced acute excitotoxicity and protect organotypic brain slices from oxygen-glucose deprivation (OGD)-induced toxicity. Male C57BL/6 mice were injected intracerebroventricularly with ONO-8713 before being subjected to 90-min middle cerebral artery occlusion (MCAO) and 96-h reperfusion. Significant reduction in infarct size was observed in groups given 0.1 (25.9 ± 4.7%) and 1.0 nmol (27.7 ± 2.8%) ONO-8713 as compared with the vehicle-treated control group. To determine the effects of ONO-8713 post-treatment on NMDA-induced excitotoxicity, mice were given a unilateral intrastriatal NMD A injection followed by one intraperitoneal injection of 10 µg/kg ONO-8713, 1 and 6 h later. Significant attenuation of brain damage (26.6 ± 4.9%) was observed at 48 h in the ONO-8713-treated group. Finally, brain slice cultures were protected (25.5 ± 2.9%) by the addition of ONO-8713 to the medium after OGD. These findings support the notion that the EP1 receptor propagates neurotoxicity and that selective blockade could be considered as a potential preventive and/or therapeutic tool against isch-emic/hypoxic neurological conditions.     

Biodistribution of doxorubicin-alkylated poly(L-lysine citramide imide) conjugates in an experimental model of peritoneal carcinomatosis after intraperitoneal administration.

Peritoneal spread is a common manifestation in ovarian and gastrointestinal cancer. Intraperitoneal (i.p.) chemotherapy after cytoreductive surgery is associated with high systemic or local toxicity. A macromolecular drug delivery system was evaluated with the aim of improving the therapeutic index of i.p. chemotherapy. Peritoneal carcinomatosis was generated in BDIX rats (n=55) by i.p. injection of 2 million DHDK12 cells. Fourteen days later, doxorubicin (DOX) and two DOX-alkylated poly(L-lysine citramide imide) conjugates bearing 9.5% and 20.5% (w/w) chemically bound drug, respectively, were given i.p. to rats at a single 2 mg DOX/kg dose. Free and polymer-bound DOX were assessed in plasma, peritoneal fluid, abdominal tissues and heart, 15 min, 2, 6, 24, 48 and 168 h after injection. According to pharmacokinetic profiles, the peritoneal fluid areas under the concentration versus time curves (AUCs) were 2 and 2.6 times greater for the conjugates (P-DOX20 and P-DOX10, respectively) than for the free drug, respectively. Conjugates crossed the peritoneal barrier slower than the free drug. For the tumor, AUCs were, respectively, 3 and 7 times higher for the conjugates than for free DOX. The elimination half-lives of the conjugates were higher than that calculated for the free drug. Only very small concentrations were detected in peripheral organs and in the heart. In contrast, significant retention and accumulation of the conjugates were found in abdominal organs, particularly in the tumor. There was no sign of macroscopic chemical peritonitis after injection of the polymer-DOX conjugates. In conclusion, the conjugates have higher elimination half-lives than free DOX and were preferentially retained in abdominal organs and in the peritoneal carcinomatosis. This feature is of clinical interest to target tumor deposits.     

Qualitative differences in knowledge structure are associated with diagnostic performance in medical students

Diagnosing is a knowledge-based skill: to diagnose one must retrieve knowledge from long-term memory and then apply this to a new clinical problem. Prior research on expertise found differences in knowledge structure between experts and novices, and it is assumed that the superior diagnostic performance of experts is somehow related to their superior knowledge structure. Here our objective was to study knowledge structure in final year medical students and to examine the association between knowledge structure and diagnostic performance. Ninety-one students participated. We used concept sorting to assess knowledge structures for four clinical problems. We performed qualitative analysis of knowledge structures, categorizing these as either problem-specific, where knowledge was predominantly structured around concepts specific to that clinical problem, or generic, where knowledge was structured around general concepts that could apply to all clinical problems. We evaluated diagnostic performance using problem-solving questions. Knowledge structure varied between different problems, but for each problem most students had problem-specific knowledge structure. These students had better diagnostic performance than those with generic structure (68.5 vs. 55.3%, d = 0.45, P = 0.004). This difference persisted after adjusting for overall medical knowledge (performance on the Medical Council of Canada Part 1 examination) and clinical problem. We found that most students organize their knowledge around problem-specific concepts, and that this type of knowledge was associated with better diagnostic performance. This may be due to easier knowledge retrieval if there is congruence between how knowledge is stored and how it is applied when diagnosing.