15 research outputs found
Ca2+ Extrusion by NCX Is Compromised in Olfactory Sensory Neurons of OMP−/− Mice
The role of olfactory marker protein (OMP), a hallmark of mature olfactory sensory neurons (OSNs), has been poorly understood since its discovery. The electrophysiological and behavioral phenotypes of OMP knockout mice indicated that OMP influences olfactory signal transduction. However, the mechanism by which this occurs remained unknown.We used intact olfactory epithelium obtained from WT and OMP(-/-) mice to monitor the Ca(2+) dynamics induced by the activation of cyclic nucleotide-gated channels, voltage-operated Ca(2+) channels, or Ca(2+) stores in single dendritic knobs of OSNs. Our data suggested that OMP could act to modulate the Ca(2+)-homeostasis in these neurons by influencing the activity of the plasma membrane Na(+)/Ca(2+)-exchanger (NCX). Immunohistochemistry verifies colocalization of NCX1 and OMP in the cilia and knobs of OSNs. To test the role of NCX activity, we compared the kinetics of Ca(2+) elevation by stimulating the reverse mode of NCX in both WT and OMP(-/-) mice. The resulting Ca(2+) responses indicate that OMP facilitates NCX activity and allows rapid Ca(2+) extrusion from OSN knobs. To address the mechanism by which OMP influences NCX activity in OSNs we studied protein-peptide interactions in real-time using surface plasmon resonance technology. We demonstrate the direct interaction of the XIP regulatory-peptide of NCX with calmodulin (CaM).Since CaM also binds to the Bex protein, an interacting protein partner of OMP, these observations strongly suggest that OMP can influence CaM efficacy and thus alters NCX activity by a series of protein-protein interactions
Quantitative Computed Tomography in COPD: Possibilities and Limitations
Chronic obstructive pulmonary disease (COPD) is a heterogeneous disease that is characterized by chronic airflow limitation. Unraveling of this heterogeneity is challenging but important, because it might enable more accurate diagnosis and treatment. Because spirometry cannot distinguish between the different contributing pathways of airflow limitation, and visual scoring is time-consuming and prone to observer variability, other techniques are sought to start this phenotyping process. Quantitative computed tomography (CT) is a promising technique, because current CT technology is able to quantify emphysema, air trapping, and large airway wall dimensions. This review focuses on CT quantification techniques of COPD disease components and their current status and role in phenotyping COPD
Hepatocellular carcinoma and the underlying mechanisms
The incidence of hepatocellular carcinoma is increasing worldwide as well as the associated risk factors, some of which include exposure to aflatoxin B1, Hepatitis B (HBV) virus and hepatitis C (HCV) virus. Mutation of tumour suppressor gene p53 at codon 249ser at exon 7 has been found to contribute significantly to replication of damaged DNA and subsequent tumour progression. The x gene of HBV (HBx) is the most common open reading frame integrated into the host genome in hepatocellular carcinoma and the integrated HBx is frequently mutated in hepatocellular carcinoma. Mutant HBx proteins still retain their ability to bind to p53 thereby attenuating DNA repair and p53-mediated apoptosis
Antidiabetic and haematinic effects of Parquetina nigrescens on alloxan induced type-1 diabetes and normocytic normochromic anaemia in Wistar rats
Background: The plant, Parquetina nigrescens is used in folklore
medicine to treat diabetes mellitus and its complications in several
parts of West Africa. Objective: To determine the effect of Parquetina
nigrescens extract on fasting blood glucose in alloxan-induced diabetic
rats. Methods: The blood glucose levels, complete blood count,
erythrocyte indices and osmotic fragility, body and organ weights were
evaluated. Results: Diabetic rats treated with the extract showed
significant (P<0.01) reduction of the blood glucose to levels
comparable to that of the non-diabetic control and those treated with
chlorpropamide (standard drug). Similarly, there was significant
(P<0.01) reduction in the complete blood count in the diabetic rats.
Discussion: The anaemia, leucopenia and thrombocytopenia associated
with the diabetes were corrected in the animals treated with the
extract and chlorpropamide. The extract also reduced the erythrocyte
osmotic fragility, body and organ weights. Parquetina nigrescens
demonstrated antidiabetic property by reducing the elevated blood
glucose in alloxan treated rats which is comparable to animals that
received the standard drug. Conclusion: Paraquetina nigrescens
stabilized the erythrocyte membrane, decreased the body weight probably
by lowering lipogenesis. However, the mechanism underlying the
antidiabetic and haematinic properties of Parquetina nigrescens remains
to be elucidated
Amelioration of carbon tetrachloride-induced hepatotoxicity and haemotoxicity by aqueous leaf extract of Cnidoscolus aconitifolius in rats
This study was conducted to explore possible protective effect of
Cnidoscolus aconitifolius (CA) leaf extract on carbon tetrachloride
(CCl4)-induced hepatotoxicity and haemotoxicity in experimental animal
models. Thirty six rats of six per group were used in this study. Group
I received 10ml/kg normal saline as control. Group II-VI rats were
administered with 1.25ml/kg body weight (bwt) of carbon tetrachloride
intraperitonealy. Animals in groups III, IV, V and VI were however
pre-treated with aqueous extract of Cnidoscolus aconitifolius at 100,
250, 500 and 750mg/kg body weight (bwt) respectively. Administration of
CCL4 in untreated rats led to microcytic hypochromic anaemia,
thrombocytopenia, increased erythrocyte fragility and stress induced
leucocytosis accompanied with significant (P<0.05) increase in
neutrophils and decrease (P<0.01) in lymphocyte counts. CCl4 also
led to significant (P<0.05) increase in serum transaminases (ALT and
AST) and phosphatase (ALP) respectively compared with control animals.
Also, CCL4 produced significant (P<0.05) increase in serum blood
urea nitrogen (BUN) and creatinine compared with normal rats.
Pre-treatment with Cnidoscolus aconitifolius leaf extract brought about
significant restoration of the haematological parameters to values that
were comparable to those of the control with concomitant decrease
(P<0.05) in the activities of the marker of hepatic damage enzymes
(ALT, AST and ALP), in a dose-dependent manner. Similarly, serum levels
of blood urea nitrogen (BUN) and creatinine were also brought to near
normal by the CA in a dose-dependent manner. From this study, we
conclude that pre-exposure to Cnidoscolus aconitifolius leaf extract
considerably reduced the effect of CCl4 on the blood parameters and
ameliorated hepatic damage by the haloalkane