Chukwuemeka R. Nwokocha

Bio: Chukwuemeka R. Nwokocha is an academic researcher from University of the West Indies. The author has contributed to research in topics: Blood pressure & Oxidative stress. The author has an hindex of 15, co-authored 74 publications receiving 676 citations.

Possible mechanisms of action of the hypotensive effect of Annona muricata (soursop) in normotensive Sprague–Dawley rats

Abstract: Context: Annona muricata Linn (Annonaceae) (soursop) is a food plant reported to have antihypertensive properties.Objective: We investigated the blood pressure reducing effect of its aqueous leaf extract and the possible mechanisms that may be responsible.Methods: Intravenous administration of an aqueous leaf extract (9.17–48.5 mg/kg) of A. muricata on the mean arterial pressure and heart rate were recorded invasively on anaesthetized, normotensive Sprague–Dawley rats. Contractile responses of rat aortic rings to the extract (0.5–4.0 mg/mL) were studied using standard organ bath techniques.Results: A. muricata (9.17–48.5 mg/kg) caused significant (p < 0.05) dose-dependent reduction in blood pressure without affecting the heart rates. The hypotensive effects were unaffected by atropine (2 mg/kg), mepyramine (5 mg/kg), propranolol (1 mg/kg) and L-NAME (5 mg/kg). A. muricata leaf aqueous extract significantly (p < 0.05) relaxed phenylephrine (10−9–10−4 M) and 80 mM KCl induced contractions in endothelium int...

Cerebrospinal Fluid Biomarkers of Alzheimer's Disease: Current Evidence and Future Perspectives.

Abstract: Alzheimer's disease is a progressive, clinically heterogeneous, and particularly complex neurodegenerative disease characterized by a decline in cognition. Over the last two decades, there has been significant growth in the investigation of cerebrospinal fluid (CSF) biomarkers for Alzheimer's disease. This review presents current evidence from many clinical neurochemical studies, with findings that attest to the efficacy of existing core CSF biomarkers such as total tau, phosphorylated tau, and amyloid-β (Aβ42), which diagnose Alzheimer's disease in the early and dementia stages of the disorder. The heterogeneity of the pathophysiology of the late-onset disease warrants the growth of the Alzheimer's disease CSF biomarker toolbox; more biomarkers showing other aspects of the disease mechanism are needed. This review focuses on new biomarkers that track Alzheimer's disease pathology, such as those that assess neuronal injury (VILIP-1 and neurofilament light), neuroinflammation (sTREM2, YKL-40, osteopontin, GFAP, progranulin, and MCP-1), synaptic dysfunction (SNAP-25 and GAP-43), vascular dysregulation (hFABP), as well as CSF α-synuclein levels and TDP-43 pathology. Some of these biomarkers are promising candidates as they are specific and predict future rates of cognitive decline. Findings from the combinations of subclasses of new Alzheimer's disease biomarkers that improve their diagnostic efficacy in detecting associated pathological changes are also presented.

Antihypertensive properties of Allium sativum (garlic) on normotensive and two kidney one clip hypertensive rats

Abstract: Summary: Allium sativum (garlic) is reported to act as an antihypertensive amidst an inconsistency of evidence. In this study, we investigated the cardiovascular effects of aqueous garlic extracts (AGE) on normotensive and hypertensive rats using the two-kidney one-clip (2K1C) model. Mean arterial blood pressure (MAP) and heart rate (HR) were measured in normotensive and 2K1C rat models anesthetized with thiopentone sodium (50 mg/kg body weight i.p.) through the left common carotid artery connected to a recording apparatus. The jugular vein was cannulated for administration of drugs. Intravenous injection of AGE (5-20 mg/kg) caused a significant (p<0.05) decrease in both MAP and HR in a dosedependent manner in both the normotensive and 2K1C models, with more effects on normotensive than 2K1C rat model. The dose of 20mg/kg of AGE significantly (p<0.05) reduced systolic (16.7 ± 2.0%), diastolic (26.7 ± 5.2%), MAP (23.1 ± 3.6%) and HR (38.4 ± 4.3%) in normotensive rats. In 2K1C group, it significantly (p<0.05) reduced systolic (22.2 ± 2.1 %), diastolic (30.6 ± 3.2%), MAP (28.2 ± 3.1%) and HR (45.2 ± 3.5%) from basal levels. Pulse pressure was significantly (P<0.05) elevated (33.3 ±5.1%) in the 2K1C group. Pretreatment of the animals with muscarinic receptor antagonist, atropine (2 mg/kg, i.v.), did not affect the hypotensive and the negative chronotropic activities of the extract. AGE caused a decrease in blood pressure and bradycardia by direct mechanism not involving the cholinergic pathway in both normotensive and 2K1C rats, suggesting a likely involvement of peripheral mechanism for hypotension.

Davidson's Principles and Practice of Medicine

Abstract: I first read Davidson 30 years ago: at that time it was already in its 5th edition. A brief comparison shows that it then contained about 440,000 words in 1,100 pages: the current edition has compressed 625,000 words into 800 pages. I think I bought it as a student because it was cheap: but also because it seemed to be comprehensive and straightforward, and I have used it as a basis for my medical knowledge ever since. So I miss some of the old pictures of the acute skin rashes such as scarlet fever: in fact infectious disease has been transferred to the back and genetic factors take the first chapters. But careful linguistic comparison will still uncover the old phrases which some of us know by heart-there are minor changes such as 'alarming reactions to intravenous iron are uncommon, but have occasionally been noted', which becomes 'alarming systemic anaphyllactic reactions can occur'. Sir Stanley Davidson made 'no attempt to describe every rare disease or syndrome, but devoted most of the space available to those disorders most commonly encountered in practice'. I have grown up with successive editions, and have gradually come to appreciate the problems of the authors in the compression of knowledge. Having got to know many of them personally as real people rather than as names I can still recommend the book. It is the essential starting point for the study of internal medicine and for many doctors will remain their base reference work. The present editors have kept up-to-date and been prepared to prune the dead wood. There are many competitors in the market, and the publishers must take care with layout and illustration, although Davidson is still the best value for money. I will continue to recommend it to my clinical students: they will need to read it and know it to pass final MB. Postgraduates will need to remember the facts, but also to be able to place them in a broader perspective. The older consultant will still happily read it, and to get to know the authors themselves is really to complete your medical education. Dr John Macleod and his team have successfully kept alive the primary objective 'to provide a rational and easily comprehensible basis for the practice of medicine'. The book is economical in price and compact in size, but still contains the essential truths for the practice of good medicine.

Oxidative Stress in Cardiovascular Diseases: Still a Therapeutic Target?

Abstract: Cardiovascular diseases (CVD) are complex entities with heterogenous pathophysiologic mechanisms and increased oxidative stress has been viewed as one of the potential common etiologies. A fine balance between the presence of reactive oxygen species (ROS) and antioxidants is essential for the proper normal functioning of the cell. A basal concentration of ROS is indispensable for the manifestation of cellular functions, whereas excessive levels of ROS cause damage to cellular macromolecules such as DNA, lipids and proteins, eventually leading to necrosis and apoptotic cell death. CVD is the main cause of death worldwide with several conditions being affected by oxidative stress. Increased ROS lead to decreased nitric oxide availability and vasoconstriction, promoting arterial hypertension. ROS also negatively influence myocardial calcium handling, causing arrhythmia, and augment cardiac remodeling by inducing hypertrophic signaling and apoptosis. Finally, ROS have also been shown to promote atherosclerotic plaque formation. This review aims at giving an introduction into oxidative stress in CVD, with special focus on endothelial dysfunction, and then examining in detail the role of oxidative stress in the most prevalent of these diseases. Finally, potential nutraceuticals and diets that might be beneficial in diminishing the burden of oxidative stress in CVD are presented.

Annona muricata (Annonaceae): A Review of Its Traditional Uses, Isolated Acetogenins and Biological Activities

Abstract: Annona muricata is a member of the Annonaceae family and is a fruit tree with a long history of traditional use. A. muricata, also known as soursop, graviola and guanabana, is an evergreen plant that is mostly distributed in tropical and subtropical regions of the world. The fruits of A. muricata are extensively used to prepare syrups, candies, beverages, ice creams and shakes. A wide array of ethnomedicinal activities is contributed to different parts of A. muricata, and indigenous communities in Africa and South America extensively use this plant in their folk medicine. Numerous investigations have substantiated these activities, including anticancer, anticonvulsant, anti-arthritic, antiparasitic, antimalarial, hepatoprotective and antidiabetic activities. Phytochemical studies reveal that annonaceous acetogenins are the major constituents of A. muricata. More than 100 annonaceous acetogenins have been isolated from leaves, barks, seeds, roots and fruits of A. muricata. In view of the immense studies on A. muricata, this review strives to unite available information regarding its phytochemistry, traditional uses and biological activities.