Sustained Na+/H+ Exchanger Activation Promotes Gliotransmitter Release from Reactive Hippocampal Astrocytes following Oxygen-Glucose Deprivation

Hypoxia ischemia (HI)-related brain injury is the major cause of long-term morbidity in neonates. One characteristic hallmark of neonatal HI is the development of reactive astrogliosis in the hippocampus. However, the impact of reactive astrogliosis in hippocampal damage after neonatal HI is not fully understood. In the current study, we investigated the role of Na⁺/H⁺ exchanger isoform 1 (NHE1) protein in mouse reactive hippocampal astrocyte function in an in vitro ischemia model (oxygen/glucose deprivation and reoxygenation, OGD/REOX). 2 h OGD significantly increased NHE1 protein expression and NHE1-mediated H⁺ efflux in hippocampal astrocytes. NHE1 activity remained stimulated during 1–5 h REOX and returned to the basal level at 24 h REOX. NHE1 activation in hippocampal astrocytes resulted in intracellular Na⁺ and Ca²⁺ overload. The latter was mediated by reversal of Na⁺/Ca²⁺ exchange. Hippocampal astrocytes also exhibited a robust release of gliotransmitters (glutamate and pro-inflammatory cytokines IL-6 and TNFα) during 1–24 h REOX. Interestingly, inhibition of NHE1 activity with its potent inhibitor HOE 642 not only reduced Na⁺ overload but also gliotransmitter release from hippocampal astrocytes. The noncompetitive excitatory amino acid transporter inhibitor TBOA showed a similar effect on blocking the glutamate release. Taken together, we concluded that NHE1 plays an essential role in maintaining H⁺ homeostasis in hippocampal astrocytes. Over-stimulation of NHE1 activity following in vitro ischemia disrupts Na⁺ and Ca²⁺ homeostasis, which reduces Na⁺-dependent glutamate uptake and promotes release of glutamate and cytokines from reactive astrocytes. Therefore, blocking sustained NHE1 activation in reactive astrocytes may provide neuroprotection following HI.     

Pulmonary pseudallescheriasis in a patient with healed tuberculosis

Pulmonary pseudallescheriasis in an immunocompetent patient without a pre-existing cavity or cyst is a rare phenomenon. We report a case of invasive pulmonary pseudallescheriasis in a lobectomised patient treated for tuberculosis. Filamentous fungi with pyriform conidia were seen in the bronchoalveolar lavage fluid .The fungus was identified as Pseudallescheria boydii on culture.     

Nitric oxide-mediated modulation of synaptic activity by astrocytic P2Y receptors

We investigated the mechanism of synaptic suppression by P2Y receptors in mixed hippocampal cultures wherein networked neurons exhibit synchronized Ca²⁺ oscillations (SCO) due to spontaneous glutamatergic synaptic transmission. Pharmacological studies suggested that SCO suppression was mediated by P2Y2/P2Y4 receptors. Immunostaining studies and characterization of ATP/UTP-stimulated Ca²⁺ responses in solitary neurons and astrocytes revealed that the SCO attenuation was effectuated by astrocytes. We demonstrate that nitric oxide released from activated astrocytes causes synaptic suppression by inhibiting neurotransmitter release. Physiological concentrations of ATP and UTP evoked NO production in astrocytes. SCO suppression was considerably diminished by removal of extracellular NO by membrane-impermeable scavenger c-PTIO or by pretreatment of cells with nitric oxide synthase inhibitor L-NAME. The nitric oxide donor DETA/NO effectively suppressed the SCO. ATP/UTP inhibited KCl-induced exocytosis at presynaptic terminals in an NO-dependent manner. In the absence of exogenously added ATP/UTP, both the NO scavenger and NOS inhibitor enhanced the frequency of SCO, implying that astrocytes release NO during spontaneous synaptic activity and exert a suppressive effect. We report for the first time that under physiological conditions astrocytes use NO as a messenger molecule to modulate the synaptic strength in the networked neurons.     

Melanocyte–keratinocyte interaction induces calcium signalling and melanin transfer to keratinocytes

Physical contact between melanocytes and keratinocytes is a prerequisite for melanosome transfer to occur, but cellular signals induced during or after contact are not fully understood. Herein, it is shown that interactions between melanocyte and keratinocyte plasma membranes induced a transient intracellular calcium signal in keratinocytes that was required for pigment transfer. This intracellular calcium signal occurred due to release of calcium from intracellular stores. Pigment transfer observed in melanocyte–keratinocyte co‐cultures was inhibited when intracellular calcium in keratinocytes was chelated. We propose that a ‘ligand‐receptor’ type interaction exists between melanocytes and keratinocytes that triggers intracellular calcium signalling in keratinocytes and mediates melanin transfer.     

Salt and osmotic stress tolerances of the C<Subscript>3</Subscript>–C<Subscript>4</Subscript> xero-halophyte <Emphasis Type="Italic">Bassia sedoides</Emphasis> from two populations differ in productivity and genetic polymorphism

The morphological, biochemical and genetic characteristics of two Bassia sedoides (Chenopodiaceae) populations in the Southern Urals were studied. The plants of the Makan and Podolsk populations differ in growth (approximately 10-fold), in water and potassium contents and Na⁺/K⁺ ratio. On the basis of the genetic assay (by isozymes, RAPD and ISSR markers) of B. sedoides from the Makan and Podolsk populations, the intraspecific differences have been identified. The more productive Makan population showed greater genetic polymorphism, whereas the less productive Podolsk population showed less genetic polymorphism. The seedlings of B. sedoides from the Makan and Podolsk populations were cultivated under low and moderate salinity (100 and 200 mM NaCl, respectively) and equivalent osmoticity generated by the two PEG concentrations. Both populations were sensitive to dehydration initiated by PEG. Podolsk seedlings were more sensitive to osmotic stress and were characterised by an increase in proline content. Low salinity (100 mM NaCl) was necessary for optimal growth of seedlings from the Makan population. They showed significantly increased fresh biomass and number of lateral shoots. The maximal growth of seedlings from Podolsk was under 0–100 mM NaCl, and their biomass was approximately 1.4-fold lower than that of the Makan seedlings. Under moderate salinity (200 mM NaCl), the Makan seedlings were more salt tolerant than the Podolsk seedlings because of maintaining a low Na⁺/K⁺ ratio. Under natural conditions, the excess of Na⁺/K⁺ ratio compared with values for optimal growth under laboratory conditions was approximately threefold for the Makan plants and approximately fivefold for the Podolsk plants. High values of the Na⁺/K⁺ ratio under natural conditions indicate a deficit of potassium in the soil. Perhaps, the degree of potassium deficiency is one of the factors influencing the differences in productivity and the level of genetic variation of B. sedoides under natural conditions.     

The association between eating behavior and polymorphisms in GRIN2B,GRIK3, GRIA1 and GRIN1 genes in people with type 2 diabetes mellitus

Molecular Biology Reports - Excess body weight is the main risk factor of type 2 diabetes. Recent studies have shown that psychological and behavioral factors affect weight. Additionally, emerging...     

In-vitro antibacterial, antifungal and cytotoxic activities of some coumarins and their metal complexes

A series of new antibacterial and antifungal coumarin-derived compounds and their transition metal complexes [cobalt (II), copper (II), nickel (II) and zinc (II)] have been synthesized, characterized and screened for their in vitro antibacterial activity against Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa, Salmonella typhi, Shigella dysenteriae, Bacillus cereus, Corynebacterium diphtheriae, Staphylococcus aureus and Streptococcus pyogenes bacterial strains and for in vitro antifungal activity against Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani, Candida glaberata. The results of these studies show the metal complexes to be more antibacterial and antifungal as compared to the uncomplexed coumarins. The brine shrimp bioassay was also carried out to study their in vitro cytotoxic properties.     

Clinical features, epidemiology, and efficacy and safety of intralesional antimony treatment of cutaneous leishmaniasis: recent experience in Turkey

A total of 1,030 patients, 40.2% men and 59.8% women, identified during the period of October 1998 to November 2002 as having cutaneous leishmaniasis (CL), were studied; 1,431 lesions were identified in the 1,030 patients. One lesion was present in 80.7% of the patients. The size of the lesions (longest axis) was 13.6 mm (standard, 12.1 mm; range 3-150 mm). Most of the lesions were of the papular type (51.2%), although several atypical clinical presentations of CL were observed. The duration of the disease ranged between 1 and 72 mo (mean duration, 10.8 mo). The clinical suspicion of CL was confirmed by the observation of amastigotes on lesion tissue samples stained by Giemsa. The test was positive in 851 of 1,030 patients (82.6%). Intralesional meglumine antimonate solution (85 mg Sb/ml, 0.2-1 ml, depending on the size of the lesion) weekly until complete cure or up to 20 wk was used for first-line therapy of 890 patients (86.4%). We found that this regimen of intralesional Sb has an efficacy of 97.2% with a low relapse rate of 3.9% and no serious adverse side effects.     

Evidence that RpoS (sigmaS) in Borrelia burgdorferi is controlled directly by RpoN (sigma54/sigmaN)

The alternative sigma factor (RpoN-RpoS) pathway controls the expression of key virulence factors in Borrelia burgdorferi. However, evidence to support whether RpoN controls rpoS directly or, perhaps, indirectly via a transactivator has been lacking. Herein we provide biochemical and genetic evidence that RpoN directly controls rpoS in B. burgdorferi.