Beta-adrenoceptor agonist treatment reverses denervation atrophy with augmentation of collagen proliferation in denervated mice gastrocnemius muscle

Daily oral administration of isoproterenol hydrochloride (60 mg/kg body weight; for 30 days) a beta-receptor agonist to normal innervated and denervated adult male Swiss albino mice confirmed its ability to induce skeletal muscle hypertrophy and reverse denervation atrophy respectively. Measurement of total tissue proteins and dry muscle mass showed 15-17% increase with 6% rise of hypertrophy index in gastrocnemius muscle. Hydroxyproline assay employed to measure the total tissue collagen exhibited 45% increase in collagen in normal innervated gastrocnemius muscle in response to beta agonist treatment. beta-adrenoceptor agonist ameliorated denervation atrophy along with further increase in collagen content of denervated gastrocnemius muscle.     

Reduction of vitrification in in vitro raised shoots of Chlorophytum borivilianum Sant. & Fernand., a rare potent medicinal herb

Reduction of vitrification in in vitro raised shoots derived from shoot bases and immature floral buds along with inflorescence axis used as explants of C. borivilianum, a rare medicinal herb is described. Shoot multiplication was obtained on MS medium with 2 mg l(-1) benzylaminopurine (BAP) + 0.1 mg l(-1) indole-3-butyric acid (IBA) and MS medium with 2 mg l(-1) kinetin (Kin) + 0.1 mg l(-1) 2,4-dichlorophenoxy acetic acid (2,4-D) from shoot bases and inflorescence axis respectively. Best multiplication rates were obtained from both the explants on MS medium with 2 mg l(-1) BAP. Vitrification of shoots in cultures appeared during the multiplication stage. Culture bottles with aerated caps reduced the vitrification to 80%. Reduction of BAP concentration from 2 mg l(-1) to zero during subsequent subcultures also minimized vitrification. Use of 0.5-2 mg l(-1) Kin produced healthy shoots when compared to BAP. In vitro raised shoots rooted on Knop salts containing iron and vitamins of MS medium, 2 mg l(-1) IBA and 0.1% activated charcoal. About 80% plantlets survived upon soil transfer. Scanning electron microscopic and image analyzer studies reveal the morphological structural differences between the leaves of normal and vitrified plantlets.     

Identification and characterization of a major Zn(II) resistance determinant of Mycobacterium smegmatis

A zinc ion-sensitive mutant of Mycobacterium smegmatis was isolated. The transposon insertion was located in zitA (MSMEG0750), a gene coding for a cation diffusion facilitator family protein. Zinc ions specifically induced expression of zitA. In silico analysis revealed that environmental and opportunistic pathogenic species contain higher numbers of cation diffusion facilitator genes than do obligate pathogens.     

Fibronectin and laminin enhance engraftibility of cultured hematopoietic stem cells

To test the hypothesis that extracellular matrix (ECM) components maintain stem cell property, murine bone marrow (BM) cells were expanded in fibronectin and laminin coated plate in the presence of cytokines. We observed significant phenotypic and functional improvement of expanded cells. In 10 days, 800-fold expansion of colony-forming unit-granulocyte erythrocyte monocyte megakaryocyte (CFU-GEMM) was observed in the cultured cells. No apparent activation of cell cycle was observed, but CD29 and very late antigen-4 (VLA-4) expression was increased, as compared to the normal BM cells. A fraction of the expanded cells became verapamil sensitive, suggesting upregulation of multi-drug resistant gene(s), as found in the primitive hematopoietic stem cells (HSCs). Competitive repopulation assay confirmed that HSCs compartment was amplified during culture. Overall, our study clearly demonstrated that ex vivo culture of murine HSCs in the presence of fibronectin and laminin resulted in expansion of primitive stem cells and improvement in the marrow engraftibility.     

Neuronal Ca2+ signaling via caldendrin and calneurons

The calcium sensor protein caldendrin is abundantly expressed in neurons and is thought to play an important role in different aspects of synapto-dendritic Ca2+ signaling. Caldendrin is highly abundant in the postsynaptic density of a subset of excitatory synapses in brain and its distinct localization raises several decisive questions about its function. Previous work suggests that caldendrin is tightly associated with Ca2+ - and Ca2+ release channels and might be involved in different aspects of the organization of the postsynaptic scaffold as well as with synapse-to-nucleus communication. In this report we introduce two new EF-hand calcium sensor proteins termed calneurons that apart from calmodulin represent the closest homologues of caldendrin in brain. Calneurons have a different EF-hand organization than other calcium sensor proteins, are prominently expressed in neurons and will presumably bind Ca2+ with higher affinity than caldendrin. Despite some significant structural differences it is conceivable that they are involved in similar Ca2+ regulated processes like caldendrin and neuronal calcium sensor proteins.     

Decorin binds myostatin and modulates its activity to muscle cells

Myostatin, a member of TGF-beta superfamily of growth factors, acts as a negative regulator of skeletal muscle mass. The mechanism whereby myostatin controls the proliferation and differentiation of myogenic cells is mostly clarified. However, the regulation of myostatin activity to myogenic cells after its secretion in the extracellular matrix (ECM) is still unknown. Decorin, a small leucine-rich proteoglycan, binds TGF-beta and regulates its activity in the ECM. Thus, we hypothesized that decorin could also bind to myostatin and participate in modulation of its activity to myogenic cells. In order to test the hypothesis, we investigated the interaction between myostatin and decorin by surface plasmon assay. Decorin interacted with mature myostatin in the presence of concentrations of Zn(2+) greater than 10microM, but not in the absence of Zn(2+). Kinetic analysis with a 1:1 binding model resulted in dissociation constants (K(D)) of 2.02x10(-8)M and 9.36x10(-9)M for decorin and the core protein of decorin, respectively. Removal of the glycosaminoglycan chain by chondroitinase ABC digestion did not affect binding, suggesting that decorin could bind to myostatin with its core protein. Furthermore, we demonstrated that immobilized decorin could rescue the inhibitory effect of myostatin on myoblast proliferation in vitro. These results suggest that decorin could trap myostatin and modulate its activity to myogenic cells in the ECM.     

Fertilization triggers localized activation of Src-family protein kinases in the zebrafish egg

Fertilization triggers activation of Src-family kinases in eggs of various species including marine invertebrates and lower vertebrates. While immunofluorescence studies have localized Src-family kinases to the plasma membrane or cortical cytoplasm, no information is available regarding the extent to which these kinases are activated in different regions of the zygote. The objective of the present study was to detect the subcellular distribution of activated Src-family kinases in the fertilized zebrafish egg. An antibody specific for the active, non-phosphorylated form of Src-family PTKs was used to detect these activated kinases by immunofluorescence. The results demonstrate that Fyn, and possibly other Src family members are activated by dephosphorylation of the C-terminal tyrosine at fertilization. The activated Src-family kinases are asymmetrically distributed around the egg cortex with an area of higher kinase activity localized adjacent to the micropyle near the presumptive animal pole. Fertilization initially caused elevation of kinase activity in the cytoplasm underlying the micropyle, but this quickly spread to involve the entire zygote cortex. Later, during egg activation, formation of the blastodisc involved concentration of active Src-family kinase in the blastodisc cortex. As cytokinesis began, activated Src-family kinases were no longer limited to the cortex, but became more evenly distributed in the clear apical cytoplasm of the blastomeres. The results demonstrate that the cortex of the zebrafish egg is functionally differentiated and that fertilization triggers localized activation of Src-family kinases at the point of sperm entry, which subsequently progresses through the entire egg cortex.     

Pulmonary hypertension in human newborns with congenital diaphragmatic hernia is associated with decreased vascular expression of nitric-oxide synthase

The molecular basis of the pathogenesis of pulmonary hypertension (PH) associated with congenital diaphragmatic hernia (CDH) is poorly understood. Variation in responses to therapeutic strategies such as nitric oxide (NO) inhalation and extracorporeal membrane oxygenation (ECMO) in patients with CDH remains a major problem in pediatric critical care. We investigated the expression pattern of NO-generating enzyme nitricoxide synthase (NOS) (both endothelial [eNOS] and inducible [iNOS] isoforms) in the lungs of CDH patients with PH and evaluated the influence of ECMO on the expression levels of these genes in an attempt to understand the underlying molecular mechanisms. Lung autopsy specimens from 23 cases of CDH not treated by ECMO and 10 ECMO-treated CDH cases were studied and compared with 11 age-matched controls. Expression of iNOS and eNOS was assessed by immunohistochemistry and video-image analysis. Expression of iNOS in the endothelium of small pulmonary arteries (external diameter≤200 μm) was significantly lower in CDH cases that had not received ECMO treatment (p=0.04). ECMO-treated CDH cases did not differ from controls in iNOS expression. Alveclar macrophages (CD68⁺ cells), of which the number also was increased, showed significantly enhanced staining for iNOS in CDH cases (p=0.03) compared with controls. The observed decrease in pulmonary expression of iNOS in patients with CDH suggests a potential role in the pathogenesis of pulmonary hypertension in newborns with CDH. ECMO treatment was correlated with induction of this enzyme, which may result in NO-mediated vasodilatation and thereby transiently reduce the pulmonary hypertension in CDH.