Sikha SahaUniversity of Leeds · Leeds Institute of Genetics, Health and Therapeutics (LIGHT)
Sikha Saha
BSc (Hons), MSc, PHD, FHEA
About
67
Publications
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Introduction
Sikha Saha currently works at the Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds. Sikha does research in Biotechnology and Cell Biology. Their most recent publication is in J Biophotonics.
Publications
Publications (67)
Up-conversion nanoparticles (UCNPs) of sodium yttrium fluoride with ytterbium and erbium ions as sensitizer and activator (β-NaYF4/Yb³⁺/Er³⁺) have been synthesised by a solvo-thermal method. The synthesised particles were found to be highly uniform in size (~50 nm) and of hexagonal crystal phase producing strong up-conversion luminescence dominated...
A stroke occurs when the blood flow to the brain is suddenly interrupted, depriving brain cells of oxygen and glucose and leading to further cell death. Neuroimaging techniques, such as computed tomography and magnetic resonance imaging, have greatly improved our ability to visualise brain structures and are routinely used to diagnose the affected...
Dual labeled contrast agents could provide better complementary information for bioimaging than available solely from a single modality. In this paper we investigate the suitability of Yb³⁺ and Er³⁺-doped BaYF5 upconversion nanoparticles (UCNPs) as both optical and X-ray micro computed tomography (μCT) contrast agents. Stable, aqueous UCNP dispersi...
The protein biomarker measurement has been well-established using ELISA (enzyme-linked immunosorbent assay), which offers good sensitivity and specificity, but remains slow and expensive. Certain clinical conditions, where rapid measurement or immediate confirmation of a biomarker is paramount for treatment, necessitate more rapid analysis. Biosens...
Upconversion nanoparticles (UCNPs) with sodium yttrium fluoride, NaYF4 (host lattice) doped with Yb³⁺ (sensitizer) and Er³⁺ (activator), were synthesized via hydrothermal route incorporating polyethyleneimine (PEI) for their long‐term stability in water. The cationic PEI modified UCNPs with diameter 20±4 nm showed a zeta potential value of +36.5 mV...
OBJECTIVE: This study was aimed to assess the effect of unilateral common carotid artery occlusion
on brain pathophysiology in rats pretreated with subchronic hypoxia.
MATERIALS AND METHODS: Rats (200 ± 20 g) were randomized into three groups: Group 1
served as sham, Group 2 were normoxic (21% O2 and 79% N2), and Group 3 were hypoxia
preconditioned...
Blood brain barrier (BBB) cells play key roles in the physiology and pathology of the central nervous system (CNS). BBB dysfunction is implicated in many neurodegenerative diseases, including Alzheimer's disease (AD). The BBB consists of capillary endothelial cells, pericytes encircling the endothelium and surrounding astrocytes extending their pro...
Eu³⁺integrated photoluminescence intensity ratio (PLIR) approach for optical detection of lactates in blood serum, plasma and confocal imaging of brain tissues has very high potential for exploitation of this technique in both in vitro monitoring and in vivo bioimaging applications for the detection of biomarkers in various diseases states. This im...
Cerebral ischemia is known to be a major cause of death and the later development of Alzheimer's disease and vascular dementia. However, ischemia induced cellular damage that initiates these diseases remain poorly understood. This is primarily due to lack of clinically relevant models that are highly reproducible. Here, we have optimised a murine m...
Upconversion nanoparticles (UCNPs) are utilized extensively for biomedical imaging, sensing, and therapeutic applications, yet the molecular weight of UCNPs has not previously been reported. Herein, we present a theory based upon the crystal structure of UCNPs to estimate the molecular weight of UCNPs: enabling insight into UCNP molecular weight fo...
Upconversion nanoparticles (UCNPs) are utilized extensively for biomedical imaging, sensing, and therapeutic applications, yet the molecular weight of UCNPs has not previously been reported. Herein, we present a theory based upon the crystal structure of UCNPs to estimate the molecular weight of UCNPs: enabling insight into UCNP molecular weight fo...
Instant measurement of elevated biomarker such as lactic acid offers the most promising approaches for early treatment and prevention of many critical diseases including cardiac arrest, stroke, septic shock, trauma, liver dysfunction, and as well as for monitoring lactic acid level during intense exercise. In the present study a unique dependence o...
Luminescence up-conversion nanoparticles (UCNPs) consisting of a NaYF4 crystal lattice doped with rare earth (RE) ions have found widespread application in bio-sensing, bio-imaging, and therapeutics; yet the molecular weight of UCNPs is not known. Lack of knowledge of molecular weight of UCNPs results in sub-optimal functionalisation and dosages of...
Background: Hyperglycemia is found to be a regulator of HIF-1α gene expression but the
regulation of HIF-1α on glucose homeostasis is unclear.
Objective: To determine whether chronic intermittent hypoxia (CIH) alters glucose regulation and such alterations can revert through treatments with either antioxidant (vitamin c) or calcium channel blocker...
In the present study, NaYF4-Yb3+/Er3+ having the composition NaYF4-18%Yb3+/2%Er3+ and NaYF4-20%Yb3+/2%Er3+ with and without the addition of PVP (polyvinyl pyrolidone) have been synthesised by a solution method using NaF, yttrium nitrate, ytterbium nitrate and erbium nitrate as precursors. Upconversion spectra of prepared nanomaterial under 980 nm l...
Stroke represents one of the major causes of death and disability worldwide, for which no effective treatments are available. The thrombolytic drug alteplase (tissue plasminogen activator or tPA) is the only treatment for acute ischemic stroke but its use is limited by several factors including short therapeutic window, selective efficacy, and subs...
Lead (Pb) is a long-known poison of environment and industrial origin. Its prolonged exposure affects cellular material and alters cellular genetics and produces oxidative damages. In this study, we investigated the exposure of chronic sustained hypoxia or lead acetate alone or in combination with or without supplementation of α-tocopherol on hepat...
Hypoxia inducible factor-1α is an important transcription factor which is necessary for
hypoxic gene expression that responds to changes in oxygen level in cell. HIF-1α remained stable and
active in the occurance of Fe2+ and oxygen but it is depleted through the Von Hippel Lindau protein
(pVHL) or Ubiquitin or Proteosome pathway. Restriction of oxy...
Over the years, nanotechnology has greatly developed, moving from careful design strategies and synthesis of novel nanostructures to producing them for specific medical and biological applications. The use of nanotechnology in diagnostics, drug delivery, and tissue engineering holds great promise for the treatment of stroke in the future. Nanoparti...
CDP-choline is an endogenous metabolite in phosphatidylcholine biosynthesis. Exogenous administration of CDP-choline has been shown to affect brain metabolism and to exhibit cardiovascular, neuroendocrine neuroprotective actions. On the other hand, little is known regarding its respiratory actions and/or central mechanism of its respiratory effect....
The present study was designed to determine the involvement of central prostaglandin synthesis on the pressor and bradycardic effect of cytidine 5′-diphosphocholine (CDP-choline). Intracerebroventricular (i.c.v.) administration of CDP-choline was made and blood pressure and heart rate were recorded in male Sprague Dawley rats throughout this study....
Nickel sulfate stimulates inducible nitric oxide synthase (i-NOS) and increases serum nitric oxide concentration by overproduction of reactive nitrogen species due to nitrosative stress. The present study was undertaken to assess possible protective role of L-ascorbic acid as an antioxidant against nickel induced pulmonary nitrosative stress in mal...
Dysfunction of glutamate transporters has been proposed to promote neuronal death in modelled cerebral ischemia. However, these studies have produced conflicting results and the changes in glutamate transporter expression have not yet been examined in a mouse focal ischemic stroke model. This study used quantitative real-time reverse-transcription...
Immunoreactive structures visualised with antibodies to glycine were prominent in areas of the nucleus of the solitary tract (NTS) surrounding the tractus solitarius, but scarcer in medial and ventral areas of the nucleus. This contrasted with a higher density, more homogenous distribution of structures labelled for gamma-aminobutyric acid (GABA)....
Neurones in the central nucleus of the amygdala (CeA) projecting to the caudal dorsomedial medulla oblongata play a key role in the autonomic expression of emotional behaviour. We have earlier shown that these projections from the CeA contain gamma-aminobutyric acid. The CeA receives a dense serotonergic innervation from the raphé nuclei and expres...
Background / Purpose: Aging is one of the most significant risk factors for stroke which represents the major cause of death and long-term disability worldwide. During an ischemic insult, extracellular glutamate levels are increased as a result of impaired glutamate uptake mechanisms, which induces calcium dependent cell death via excessive activat...
We evaluated the effect of L-ascorbic acid and alpha-tocopherol supplementation on plasma and whole brain nitric oxide level and antioxidant status in nickel sulfate- or lead acetate- treated male albino rats. Nitric oxide and lipid peroxide levels in whole brain tissue and plasma increased following nickel and lead treatment but significantly retu...
Expression of GABA(B) receptor messenger RNA (mRNA) in the central nervous system was compared between the spontaneously hypertensive (SHR) and normotensive Wistar Kyoto (WKY) rat. Polymerase chain reaction (PCR) revealed all the isoforms except B1e in cortex, hypothalamus, and medulla oblongata. In the nucleus of the solitary tract (NTS) and ventr...
The central nucleus of amygdala (CeA) participates in cardiovascular regulation during emotional behaviour but it has not been established whether any of these effects are mediated through its direct connections to blood pressure-regulating neurones in the rostral ventrolateral medulla (RVLM). The RVLM contains barosensitive neurones that maintain...
1. One of the key areas that links psychologically induced stress with the blood pressure-regulatory system is the central nucleus of the amygdala (CeA). This is an integratory forebrain nucleus that receives input from higher centres in the forebrain and has extensive connections with the hypothalamus and the medulla oblongata, areas involved in t...
Using whole-cell patch-clamp recordings in conjunction with post hoc anatomy we investigated the physiological properties of hippocampal stratum oriens and stratum pyramidale inhibitory interneurones, before and following the induction of pharmacologically evoked gamma frequency network oscillations. Prior to kainate-induced transient epochs of gam...
The medial septal diagonal band complex (MS/DB), made up of cholinergic and GABAergic neurons, plays an important role in the generation of the hippocampal theta rhythm. A GABAergic neuron type in the MS/DB that has fast spiking properties was shown previously to contain parvalbumin immunoreactivity and to form axosomatic connections with unidentif...
The expression of alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptor subunits GluR1-4 in the nucleus of the solitary tract (NTS) of adult Wistar rats was examined by polymerase chain reaction (PCR), and the neuronal localisation of these receptor subunits in the NTS were confirmed by immunohistochemistry using subunit-specific...
The ionotropic glutamate receptor subunits expressed by vagal preganglionic neurones in the rat medulla oblongata were examined by using fluorescence immunolabelling combined with retrograde neuronal tracing. The general population of these neurones in the medulla was identified by intraperitoneal injections of Fluorogold and also with choline acet...
Synaptic terminals in the nucleus of the solitary tract (NTS) from axons originating in the central nucleus of the amygdala (CeA) are known to contain gamma-aminobutyric acid (GABA) immunoreactivity. Here, we have investigated whether such projections contain neuropeptides as putative co-transmitters. Somata in the medial and lateral CeA that were...
Axon terminals synapsing on neurones in the nucleus tractus solitarii (NTS) that originate from the central nucleus of the amygdala (CeA) have been shown to contain gamma-aminobutyric acid (GABA) immunoreactivity. Here we investigated whether such terminals also contain somatostatin (SOM), a neuropeptide found in axons distributed throughout the NT...
Expression of mRNAs encoding seven GABA(A) receptor subunits (alpha1, alpha2, alpha3, alpha5, beta2, beta3, gamma2) in the nucleus tractus solitarii (NTS) of rat medulla oblongata was examined by reverse transcription-polymerase chain reaction (RT-PCR). All subunit mRNAs, except alpha5, were clearly detected. Band densities produced by alpha1, alph...
The central nucleus of the amygdala is involved in the modulation of autonomic, somatic and endocrine functions, as well as behavioural responses to stressful stimuli. Anatomical and physiological studies have suggested that this nucleus sends projections to the nucleus of the solitary tract, the primary site of termination of vagal and glossophary...
Postembedding immunogold labeling methods applied to ultrathin and semithin sections of cat dorsomedial medulla showed that neuronal perikarya, dendrites, myelinated and nonmyelinated axons, and axon terminals in the nucleus tractus solitarii contain glycine immunoreactivity. Light microscopic observations on semithin sections revealed that these i...
Using electron microscopic immunohistochemistry we have shown that strong glutamate-immunoreactivity (glutamate-ir) is present in neuronal cell bodies of the nodose ganglion, axons in the tractus solitarius and afferent terminals in the nucleus tractus solitarii. Vagal afferent fibres were specifically labelled by transganglionic retrograde transpo...
Neurophysiological and pharmacological evidence suggests that glutamate, gamma-aminobutyric acid and tachykinins (substance P and neurokinin A) each have a role in cardiovascular regulation in the nucleus tractus solitarii. This study describes the ultrastructural relationships between nerve terminals immunoreactive for these substances in the nucl...
We have used the post-embedding immunogold labelling method using antibodies to gamma-aminobutyric acid (GABA) to obtain quantitative data on the distribution, frequency, postsynaptic targets and ultrastructural characteristics of GABA-immunoreactive (GABA-IR) boutons in the trigeminal motor nucleus of rats. We have also combined this method with h...
We have used pre-embedding EM immunohistochemical methods to obtain quantitative data on the frequency and post-synaptic targets of 5-hydroxytryptamine-immunoreactive (5-HT-IR) boutons within the rat V motor nucleus. Thirteen percent (69/531) of all synaptic contacts in the motor nucleus involved 5-HT-IR boutons. Seventy-four percent of 5-HT-IR bou...
We report here a method that allows simultaneous visualisation of two antigens within single neurones. In essence this involves the combined use of horseradish peroxidase and alkaline phosphatase reactions to visualise two markers. Using this method we show that ChAT-and CGRP-like immunoreactivity can be co-localised within single neurones of the V...
Projects
Project (1)
Manufacturability of upconversion nanoparticles, detailed structural characterization, surface functionalisation and development of particles suitable for multiple sensing and dual mode imaging, in vitro and in vivo application of dual mode UCNPs; Collaborations: Structural Characterisation: SuperSTEM Daresbury-EPSRC National Research Facility for Advanced Electron Microscopy; Diamond Ltd.
Industries involved: Centre for Process and Innovation (CPI) Ltd. (manufacturing and scale up), Eluceda Ltd., Avacta (Affimer Technology)
