Met degradation: more than one stone to shoot a receptor down

The receptor tyrosine kinase Met and its high-affinity ligand, the hepatocyte growth factor/scatter factor (HGF/SF), are essential to embryonic development. Deregulation of their signaling is associated with tumorigenesis and metastasis, notably through receptor overexpression. It is thus important to understand the mechanisms controlling Met expression. The ligand-dependent internalization of Met and its subsequent degradation in the lysosomal compartment are well described. This process is known to attenuate downstream Met signaling pathways. Yet internalized Met takes part directly in intracellular signaling by chaperoning signaling factors in the course of its trafficking. Furthermore, recent studies describe various new degradation mechanisms of membrane-anchored Met, involving proteolytic cleavages or association with novel partners. Although all these degradations are ligand-independent, they share, to different extents, some common features with canonical HGF/SF-dependent degradation. Interestingly, activated Met variants display resistance to degradation, suggesting defective degradation is involved in tumorigenesis. Conversely, forced degradation of Met through reinduction of one or more degradation pathways is a promising therapeutic strategy.     

Health System Barriers to Access and Use of Magnesium Sulfate for Women with Severe Pre-Eclampsia and Eclampsia in Pakistan: Evidence for Policy and Practice

Severe pre-eclampsia and eclampsia are rare but serious complications of pregnancy that threaten the lives of mothers during childbirth. Evidence supports the use of magnesium sulfate (MgSO4) as the first line treatment option for severe pre-eclampsia and eclampsia. Eclampsia is the third major cause of maternal mortality in Pakistan. As in many other Low- and Middle-Income Countries (LMIC), it is suspected that MgSO4 is critically under-utilized in the country. There is however a lack of information on context-specific health system barriers that prevent optimal use of this life-saving medicine in Pakistan. Combining quantitative and qualitative methods, namely policy document review, key informant interviews, focus group discussions and direct observation at health facility, we explored context-specific health system barriers and enablers that affect access and use of MgSO4 for severe pre-eclampsia and eclampsia in Pakistan. Our study finds that while international recommendations on MgSO4 have been adequately translated in national policies in Pakistan, the gap remains in implementation of national policies into practice. Barriers to access to and effective use of MgSO4 occur at health facility level where the medicine was not available and health staff was reluctant to use it. Low price of the medicine and the small market related to its narrow indications acted as disincentives for effective marketing. Results of our survey were further discussed in a multi-stakeholder round-table meeting and an action plan for increasing access to this life-saving medicine was identified.     

Biological control of root rot-root knot disease complex of tomato

Efficacy of Pseudomonas aeruginosa alone or in combination with Paecilomyces lilacinus was evaluated in the control of root-knot nematode and root-infecting fungi under laboratory and field conditions. Ethyl acetate extract (1 mg/ml) of P. lilacinus and P. aeruginosa,respectively, caused 100 and 64% mortality of Meloidogyne javanica larvae after 24 h. Ethyl acetate fractions of biocontrol agents were more effective than hexane extracts in the suppression of M. javanica larvae, indicating that active nematicidal compounds are intermediary in polarity. In field experiments, biocontrol fungus and bacterium significantly suppressed soilborne root-infecting fungi including Macrophomina phaseolina, Fusarium oxysporum, Fusarium solani, Rhizoctonia solani and Meloidogyne javanica, the root-knot nematode. P. lilacinus parasitized eggs and female of M. javanica and this parasitism was not significantly influenced in the presence of P. aeruginosa. P. aeruginosa was reisolated from the inner root tissues of tomato, whereas P. lilacinusdid not colonize tomato roots. This revised version was published online in June 2006 with corrections to the Cover Date.     

K cell cytotoxicity against antibody-coated chicken erythrocytes in tumor-bearing mice: its development with progressively growing tumor and the effect of immunization against the tumor.

Antibody-dependent (K cell) cytotoxic activity of spleen cells from mice bearing a chemically induced fibrosarcoma has been studied by using antibody-coated chicken erythrocytes as target cells. Spleen cells from tumor-bearing animals caused a significantly greater degree of target cells destruction than did those from control animals. The elevated cytotoxic activity in tumor-bearing animals increased with time after the tumor inoculation and correlated directly with the size of the tumor. The development of increased cytotoxic activity could be circumvented by surgical removal of the tumor. Mice that received x-irradiated tumor cells of x-irradiated tumor cells followed by a live challenge did not show a tumor growth and also failed to show increased K cell cytotoxic activity. It has been concluded that the increased K cell activity results directly from the active growth of tumor. The role of K cells in immunosurveillance has been discussed.     

PGE2 and PGF2α biosynthesis in stimulated and nonstimulated peritoneal preparations containing macrophages

The biosynthesis of PGE₂ and PGF_2α was measured in intact peritoneal exudate preparations obtained fom $\text{C. parvum}$-treated and control C₃H mice. Although both the control and stimulated preparations biosynthesized PGF_2α and PGE₂ from [1–14C] arachidonic acid, the stimulated preparations generated more of both prostaglandins than did nonstimulated preparations, probably as a result of increased synthesis within macrophages. Increased transformation of PGE₂ into PGF_2α 9-ketoreductase was noted in stimulated preparations when compared to that in control cells. The data suggest that stimulated macrophages are capable of generating increased quantities of PGF_2α and therefore might function as one source of this substance in resolving inflammatory reactions.     

Monitoring the in vitro enzyme-mediated degradation of degradable poly(ester amide) for controlled drug delivery by LC-ToF-MS

To scrutinize materials for specific biomedical applications, we need sensitive and selective analytical methods that can give more insight into the process of their biodegradation. In the present study, the enzymatic degradation of multiblock poly(ester amide) based on natural amino acids, such as lysine and leucine, was performed with serine proteases (α-chymotrypsin (α-CT) and proteinase K (PK)) in phosphate-buffered saline solution at 37 °C for 4 weeks. Fully and partially degraded water-soluble products were analyzed by liquid chromatography hyphenated with time-of-flight mass spectrometry using an electrospray interface (LC-ESI-ToF-MS). Tracking the release of monomeric and oligomeric products into the enzyme media during the course of enzymatic degradation revealed the preferences of α-CT and PK toward ester and amide bonds: both α-CT and PK showed esterase and amidase activity. Although within the experimental time frame up to 30 and 15% weight loss was observed in case of α-CT and PK, respectively, analysis by size exclusion chromatography showed no change in the characteristic molecular-weight averages of the remaining polymer. This suggests that the enzymatic degradation occurs at the surface of this biomaterial. A sustained and linear degradation over a period of 4 weeks supports the potential of this class of poly(ester amide)s for drug delivery applications.     

Serum netrin and VCAM-1 as biomarker for Egyptian patients with type IΙ diabetes mellitus

ObjectiveThis study aimed to evaluate the serum level of netrin and soluble vascular cell adhesion molecule 1 (VCAM-I) in patients with type IΙ diabetes mellitus (T2DM) and evaluate the association of their levels with the development of a diabetic complication.Patients and methodsThis study was carried out on type II diabetic patients with and without complications and healthy individuals served as controls. All subjects were submitted to the estimation of serum lipid profile, serum creatinine, urinary albumin/creatinine ratio (ACR), fasting blood glucose (FBG), glycated hemoglobin (HbA1c), visceral adiposity index (VAI), atherogenic index of plasma (AIP), lipid accumulation product (LAP) and detection of serum level of netrin1 and VCAM1.ResultsDiabetic patients with complications had significantly higher serum levels of creatinine, ACR, cholesterol, Triglyceride, low-density lipoprotein, netrin1, and VCAM1 than diabetic patients without complications. Likewise, the level of VAI and LAP as markers of excessive body fat were significantly higher in diabetic patients with complications than diabetic patients without complications. The netrin1 and VCAM1 were a significant discriminator of T2DM renal complications with a sensitivity of 96%, 90%, and specificity of 82.7%, 91.3% respectively.ConclusionIt can be concluded that serum netrin1 and VCAM1 correlated significantly with markers of excessive body fat, a renal complication in the patient with type 2 diabetes mellitus.     

Lead contamination affects the primary productivity traits,biosynthesis of macromolecules and distribution of metal in durum wheat (Triticumdurum L.)

Lead (Pb) pollution emerged as an international issue particularly during second and third industrial revolution and is of serious global concern. Cereal crops have shown different capabilities, innate variability and mechanisms to cope with heavy metals present in their environment. Keeping in view the perspectives of food security and safety with increasing demand for Triticum durum L. it becomes imperative to appraise sustainability potential of the crop for Pb contaminated soils. The current study was conducted to test the hypothesis that T. durum germplasm holds genetic variability to evolve under Pb contamination through modulations of morpho-biochemical parameters of selective advantage. The performance of nine T. durum L. cultivars (CBD25, CBD46, CBD58, CBD59, CBD63, CBD66, CBD68, CBD69 and CBD82) was evaluated following exposure to varying Pb levels (control, 10, 20 and 40 mg kg⁻¹) in soil. Growth, biosynthesis of macromolecules and metal distribution in plant parts were assessed using valid procedures and protocols. The cultivars exhibited a differential degree of tolerance to Pb and among the tested germplasm, CBD59 performed better followed by CBD63 and CBD66 for their primary productivity traits, biosynthesis of pigments and other macromolecules (amino acids, proteins and sugar) along with resilience for Pb uptake and its consequent bioaccumulation in grains. The traits used in the study served as strong predictors to provide superior/selective ability to survive under contaminated environment. The study signified that metal tolerance/sensitivity in the cultivars is independent of magnitude of metal stress, growth responses and Pb accumulation in plant parts hence varied in space and time. The existence of genetic variability, which is a pre-requisite for selection can definitely be of great advantage for future breeding projects to develop high yielding varieties/ cultivars of durum wheat with Pb free grains to assure food security and safety.     

The effects of aerobic exercise training on the age-related lipid peroxidation, Schwann cell apoptosis and ultrastructural changes in the sciatic nerve of rats

The potential role of exercise in preventing the age-related spontaneous peripheral neuropathy has not been studied. We examined the effects of long-term aerobic exercise training on lipid peroxidation, Schwann cell (SC) apoptosis and ultrastructural changes in the sciatic nerve of rats during aging. Three groups of 12-week old Wistar rats ran on a treadmill for 6, 9 and 12 months (exercise trained (ET) group, n=10 each) according to an exercise training program targeted at a speed of 22 m/min (at 7 degrees incline), 60 min/day, 6 days/week. Three corresponding groups of untrained rats were used as the controls (sedentary (SED) group). At the end of each period, sciatic nerve biopsies were performed, and processed for biochemical, immunohistochemical and ultrastructural analyses. The results showed that aging was associated with an increased level of nerve malondialdehyde (MDA, marker of lipid peroxidation) and a higher number of SC apoptosis in SED group. The SED group showed irregular nerve fibers with thin myelin sheaths and areas of myelin-axon detachment. However, the ET group had significantly diminished nerve lipid peroxidation and SC apoptosis. In the ET group, nerve fibers had a thick myelin sheath with frequent folding. These findings suggest that aerobic exercise training protects peripheral nerves by attenuating oxidative reactions, and preserving SCs and myelin sheath from pathologic changes, which occur during normal aging.     

Effects of moderate exercise and oat beta-glucan on lung tumor metastases and macrophage antitumor cytotoxicity.

Both moderate exercise and the soluble fiber beta-glucan can have beneficial effects on the initiation and growth of tumors, but the data are limited, and there is no information on their combined effects. This study tested the independent and combined effects of short-term moderate-exercise training and the soluble oat fiber beta-glucan (ObetaG) on the metatastic spread of injected tumor cells and macrophage antitumor cytotoxicity. Male C57BL/6 mice were assigned to one of four groups: exercise (Ex)-H2O, Ex-ObetaG, control (Con)-H2O, or Con-ObetaG. ObetaG was fed in the drinking water for 10 days before tumor administration and death. Exercise consisted of treadmill running (1 h/day) for 6 days. After rest or exercise on the last day of training, syngeneic B16 melanoma cells (2 x 10(5)) were administered via intravenous injection (n = 8-11 per group). Lungs were removed 14 days later, and tumor foci were counted. Additional mice (n = 8 per group) were killed, and peritoneal macrophages were assayed for cytotoxicity against the same mouse tumor cell line at various effector-to-target ratios. Both moderate exercise and ObetaG decreased lung tumor foci and increased macrophage cytotoxicity. However, there were no differences in lung tumor foci and macrophage cytotoxicity between Ex-ObetaG and either Ex-H2O or Con-ObetaG. These data suggest that, although not additive in their effects, both short-term moderate-exercise training and consumption of the soluble ObetaG can decrease the metatastic spread of injected B16 melanoma cells, and these effects may be mediated in part by an increase in macrophage cytotoxicity to B16 melanoma.