Persistent Acidic Environment Induces Impaired Phagocytosis via ERK in Microglia

Acidic environment evoked by stroke, traumatic brain injury, and Alzheimer’s disease may change the functional properties of microglia. Nevertheless, the underlying mechanisms of functional changes in microglia remain unclear. In this study, we found that acidic stimuli (pH 6.8) increased rapidly interleukin (IL)-1β and IL-6 mRNA levels and subsequently reduced IL-10, transforming growth factor (TGF)-β1, Cx3cr1, and P2ry12 as the exposure time to acidic environment increase in BV2 cells. In addition, persistent acidic environment (pH 6.8 for 6 h) induced impaired phagocytic function in BV2 cells. Short-term acidic exposure (pH 6.8 for 30 min) increased cyclic AMP (cAMP) and phospho-protein kinase A (PKA) but inhibited phospho-extracellular signal-regulated kinase (p-ERK). However, under persistent acidic environment (pH 6.8 for 6 h), cyclic AMP and PKA were normalized and p-ERK was increased with TDAG8 (T cell death associated gene 8; GPR65) reduction. FR 180,204, an ERK inhibitor, rescued the persistent acidic environment-induced functional changes in BV2 cells and its effect was recapitulated in primary neonatal microglia. Thus, we propose that ERK targeting may be an alternative strategy to restore microglial dysfunction in the central nervous system (CNS) acidic environment in various neurological disorders.

     

Mixed infections with Opisthorchis viverrini and intestinal flukes in residents of Vientiane Municipality and Saravane Province in Laos

Faecal examinations for helminth eggs were performed on 1869 people from two riverside localities, Vientiane Municipality and Saravane Province, along the Mekong River, Laos. To obtain adult flukes, 42 people positive for small trematode eggs (Opisthorchis viverrini, heterophyid, or lecithodendriid eggs) were treated with a 20-30 mg kg(-1) single dose of praziquantel and purged. Diarrhoeic stools were then collected from 36 people (18 in each area) and searched for helminth parasites using stereomicroscopes. Faecal examinations revealed positive rates for small trematode eggs of 53.3% and 70.8% (average 65.2%) in Vientiane and Saravane Province, respectively. Infections with O. viverrini and six species of intestinal flukes were found, namely, Haplorchis taichui, H. pumilio, H. yokogawai, Centrocestus caninus, Prosthodendrium molenkampi, and Phaneropsolus bonnei. The total number of flukes collected and the proportion of fluke species recovered were markedly different in the two localities; in Vientiane, 1041 O. viverrini (57.8 per person) and 615 others (34.2 per person), whereas in Saravane, 395 O. viverrini (21.9 per person) and 155207 others (8622.6 per person). Five people from Saravane harboured no O. viverrini but numerous heterophyid and/or lecithodendriid flukes. The results indicate that O. viverrini and several species of heterophyid and lecithodendriid flukes are endemic in these two riverside localities, and suggest that the intensity of infection and the relative proportion of fluke species vary by locality along the Mekong River basin.     

Mechanical collapse of confined fluid membrane vesicles

Compact cylindrical and spherical invaginations are common structural motifs found in cellular and developmental biology. To understand the basic physical mechanisms that produce and maintain such structures, we present here a simple model of vesicles in confinement, in which mechanical equilibrium configurations are computed by energy minimization, balancing the effects of curvature elasticity, contact of the membrane with itself and the confining geometry, and adhesion. For cylindrical confinement, the shape equations are solved both analytically and numerically by finite element analysis. For spherical confinement, axisymmetric configurations are obtained numerically. We find that the geometry of invaginations is controlled by a dimensionless ratio of the adhesion strength to the bending energy of an equal area spherical vesicle. Larger adhesion produces more concentrated curvatures, which are mainly localized to the “neck” region where the invagination breaks away from its confining container. Under spherical confinement, axisymmetric invaginations are approximately spherical. For extreme confinement, multiple invaginations may form, bifurcating along multiple equilibrium branches. The results of the model are useful for understanding the physical mechanisms controlling the structure of lipid membranes of cells and their organelles, and developing tissue membranes.     

Membrane conductance in trained and untrained subjects using either steady state or single breath measurements of NO transfer.

The aim of this work was to define the relationship between membrane conductance for NO (Dm) and physical activity by using either the steady state NO transfer (T(LNO)SS) or the single breath method (T(LNO)SB), making the hypothesis that NO transfer is only limited by the membrane. Alterations in T(LNO)SS with lung volume during tidal ventilation were measured in six subjects at rest and during steady exercise at 30, 60, and 80% of maximal aerobic power (MAP). A fast responding chemoluminescent NO analyser was used. Two calculation methods were used by sampling NO: (1) at mid-tidal volume, (2) in the middle of the alveolar plateau. T(LNO)SB at rest and maximal oxygen consumption (V(.-)O(2)max) were also measured in 18 other subjects. At rest T(LNO)SS with method 2 was 192% of the value given by method 1. T(LNO)SS with method 1 increased by 50% with 80% MAP as it did not change with method 2. Method 2 seemed inaccurate. T(LNO)SB at rest, which is closely related to Dm, was correlated to age and V(.-)O(2)max, T(LNO)SB=182-1.2 age+24.3 V(.-)O(2) max(l min(-1)) (p<0.01, r(2)=0.72). The T(LNO)SS and T(LNO)SB versus lung volume relationships suggest an influence of the breathing pattern on Dm. Dm can be estimated either by these two NO transfer methods, however the use of the T(LNO)SS method is highly sensitive to the alveolar sampling level. Dm increase during exercise is a function of MAP. Dm at rest decreases with age as it increases with MAP.     

Novel and recurrent mutations in the TAT gene in Tunisian families affected with Richner–Hanhart Syndrome

Tyrosinemia type II, also designated as oculocutaneous tyrosinemia or Richner–Hanhart syndrome (RHS), is a very rare autosomal recessive disorder. In the present study, we report clinical features and molecular genetic investigation of the tyrosine aminotransferase (TAT) gene in two young patients, both born to consanguineous unions between first-degree cousins. These two unrelated families originated from Northern and Southern Tunisia. The clinical diagnosis was based on the observation of several complications related to Richner–Hanhart syndrome: recurrent eye redness, tearing and burning pain, photophobia, bilateral pseudodendritic keratitis, an erythematous and painful focal palmo-plantar hyperkeratosis and a mild delay of mental development. The diagnosis was confirmed by biochemical analysis. Sequencing of the TAT gene revealed the presence of a previously reported missense mutation (c.452G > A, p.Cys151Tyr) in a Tunisian family, and a novel G duplication (c.869dupG, p.Trp291Leufs*6). Early diagnosis of RHS and protein-restricted diet are crucial to reduce the risk and the severity of long-term complications of hypertyrosinemia such as intellectual disability.     

Plasmodesmal receptor-like kinases identified through analysis of rice cell wall extracted proteins

In plants, plasmodesmata (PD) are intercellular channels that function in both metabolite exchange and the transport of proteins and RNAs. Currently, many of the PD structural and regulatory components remain to be elucidated. Receptor-like kinases (RLKs) belonging to a notably expanded protein family in plants compared to the animal kingdom have been shown to play important roles in plant growth, development, pathogen resistance, and cell death. In this study, cell biological approaches were used to identify potential PD-associated RLK proteins among proteins contained within cell walls isolated from rice callus cultured cells. A total of 15 rice RLKs were investigated to determine their subcellular localization, using an Agrobacterium-mediated transient expression system. Of these six PD-associated RLKs were identified based on their co-localization with a viral movement protein that served as a PD marker, plasmolysis experiments, and subcellular localization at points of wall contact between spongy mesophyll cells. These findings suggest potential PD functions in apoplasmic signaling in response to environmental stimuli and developmental inputs.     

Physiological roles of preproghrelin-derived peptides in GH secretion and feeding

Among the factors playing a crucial role in the regulation of energy metabolism, gastro-intestinal peptides are essential signals to maintain energy homeostasis as they relay to the central nervous system the informations about the nutritional status of the body. Among these factors, preproghrelin is a unique prohormone as it encodes ghrelin, a powerful GH secretagogue and the only orexigenic signal from the gastrointestinal tract and obestatin, a proposed functional ghrelin antagonist. These preproghrelin-derived peptides may contribute to balance energy intake, metabolism and body composition by regulating the activity of the GH/IGF-1 axis and appetite. Whereas the contribution of ghrelin has been well characterized, the role of the more recently identified obestatin, in this regulatory process is still controversial. In this chapter, we describe the contribution of these different preproghrelin-derived peptides and their receptors in the regulation of GH secretion and feeding. Data obtained from pharmacological approaches, mutant models and evaluation of the hormones in animal and human models are discussed.     

Association study of microRNA polymorphisms with hepatocellular carcinoma in Korean population

Background

Recent studies have suggested that common genetic polymorphisms alter the processing of microRNA (miRNA) and may be associated with the development and progression of cancer.

Patients and methods

The association of miRNA polymorphisms with HCC survival was analyzed in 159 HCC patients and 201 controls by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method.

Results

The risk of HCC was significantly lower for the miR-499A>G, AG + GG in HCC patients (AOR = 0.603, 95% CI = 0.370–0.984) and hepatitis B virus (HBV)-related HCC patients (AOR = 0.561, 95% CI 0.331–0.950). In addition, the risk of HCC was significantly lower for the miR-149C>T, CT and CT + CC in HCC patients (CT; AOR = 0.542, 95% CI = 0.332–0.886, CT + CC; AOR = 0.536, 95% CI = 0.335–0.858) and HBV-related HCC patients (CT: AOR = 0.510, 95% CI 0.305–0.854, CT + CC: AOR = 0.496, 95% CI 0.302–0.813). The miR-149C>T polymorphism was also associated with survival rate of HCC patients in OKUDA II stage.

Conclusions

miR-149C>T and miR-499A>G were associated with HBV-related HCC. Further studies on larger populations will need to be conducted to confirm these results.     

Chitin and chitosan preparation from shrimp shells using optimized enzymatic deproteinization

Different crude microbial proteases were applied for chitin extraction from shrimp shells. A Box–Behnken design with three variables and three levels was applied in order to approach the prediction of optimal enzyme/substrate ratio, temperature and incubation time on the deproteinization degree with Bacillus mojavensis A21 crude protease. These optimal conditions were: an enzyme/substrate ratio of 7.75 U/mg, a temperature of 60 °C and an incubation time of 6 h allowing to predict 94 ± 4% deproteinization. Experimentally, in these optimized conditions, a deproteinization degree of 88 ± 5% was obtained in good agreement with the prediction and larger than values generally given in literature. The deproteinized shells were then demineralized to obtain chitin which was converted to chitosan by deacetylation and its antibacterial activity against different bacteria was investigated. Results showed that chitosan dissolved at 50 mg/ml markedly inhibited the growth of most Gram-negative and Gram-positive bacteria tested.