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Design of Immunobiosensors for Detection of Tumor-Associated Anti-P53 Autoantibodies: Method Development

- Adeniyi, Omotayo Kayode

Authors: Adeniyi, Omotayo Kayode
Date: 2020
Subjects: Uncatalogued
Language: English
Type: thesis , text , Doctoral , PhD
Identifier: http://hdl.handle.net/10962/162988 , vital:41002 , 10.21504/10962/162988
Description: Introduction -- Experimental -- Label-Free Impedimetric Sensing of Anti-P53ab... -- Fluorescent detection of Anti-P53ab -- Peroxidase-like activity of Fe3O4@SiNP-APTES-Au@Pd... -- Colorimetric detection of Anti-P53ab , Thesis (PhD)--Rhodes University, Science Faculty, Department of Chemistry, 2020. , Detection and profiling of circulating tumor-associated autoantibodies (TAAbs) are useful for screening and early-stage diagnosis of asymptomatic lung cancer. Immunobiosensor technologies aimed to accomplish the highly sensitive, rapid and low-cost detection of TAAbs can improve the early-stage detection of lung cancer. Immunobiosensors for the detection of anti-P53-tumour associated autoantibodies have been developed in this work. The design of sensing interfaces with immobilized P53 protein (P53ag) as a sensing element layer on a solid interface was investigated. Several methods of detecting anti-P53-antibodies (anti-P53ab) were investigated. These methods are label-free detection using electrochemical impedance spectroscopy (EIS) and two label techniques. The label-free electrochemical techniques utilize gold electrode pre-modified with a conducting layer of electrochemically grafted phenylethylamine for covalent immobilization of P53ag. The limit of anti-P53ab detection with the label-free EIS was 103.0 pg.ml-1. The labeled technique developed utilizes fluorescent, and peroxidase-like nanomaterial labeled antibody as a detection probe. For the fluorescence detection, fluorescent silica nanoparticles were synthesized by overloading FITC into the silica matrix and conjugated to detection antibody (anti-IgG). The detection of the anti-P53ab was based on the dissolution of the silica nanoparticles to release the loaded dye as a signal amplification strategy. The fluorescence detection was carried out on a microplate, and magnetic bead modified P53-antigen platforms and limit of detection (LoD) were 42.0 fg.ml-1 and 3.3 fg.ml-1 for anti-P53ab; respectively. Fe3O4@SiNP-APTES-Au@Pd hybrid nanoparticles were synthesized, and their peroxidase-like activity and colorimetric detection were evaluated. The Fe3O4@SiNP-APTES-Au@Pd exhibited comparable activity to HRP. The Fe3O4@SiNP-APTES-Au@Pd was conjugated to protein-G-anti-IgG for the detection of anti-P53ab on a microplate and cellulose paper platforms. The LoD was 20.0 fg.ml-1 and 63.0 fg.ml-1 for the microplate and cellulose paper platform; respectively. The potential application of the designed immunobiosensor was evaluated in simulated serum samples. The developed sensors showed higher detection sensitivity, stability and had a lower detection limit for anti-P53ab when compared with the ELISA based detection. The results have provided alternative and effective quantification approaches to ELISA and a promising future for multiplexed detection of tumor-associated autoantibodies. The developed methodologies in this thesis could be applied for the detection of other autoantibodies in other cancer types and auto-immune diseases.
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Date Issued: 2020

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The design, synthesis and antiplasmodial activity of a series of halogenated fosmidomycin analogues and hybrid drugs

- Afolayan, Anthonia Folake

Authors: Afolayan, Anthonia Folake
Date: 2012
Subjects: Uncatalogued
Language: English
Type: text , Thesis , Doctoral , PhD
Identifier: http://hdl.handle.net/10962/64370 , vital:28538
Description: Malaria continues to be a devastating disease and a major cause of death in sub-Saharan Africa. With resistance against most of the available antimalarial drugs, there is a need for ongoing research and development of antimalarial agents. Fosmidomycin and its acetyl analogue FR900098 have been identified as potent inhibitors of Plasmodium falciparum, the causative agent of the most deadly form of malaria. Clinical trials of these agents have revealed poor absorption due to their high hydrophilicity. In the present studies the effect of halogenation of the acyl chain as well as the biological effect of extending the acyl sidechain was explored. This provided the basis on which fosmidomycin hybrids were designed to investigate the feasibility of hybrid extending into NADPH binding pocket. Synthesis of a series of halogenated FR900098 analogues was carried out in three stages. This included i) The introduction of the phosphonate group by reaction with 1,3dibromopropane in an Arbuzov reaction, ii) The introduction of a hydroxamate group by reaction of the propyl phosphonate by means of a nucleophilic substitution reaction with BocNHOBn and iii) The introduction of a halogenated acyl side chain on a protected fosmidomycin backbone. The synthesis of fosmidomycin-hybrids for which chloroquinefosmidomycin hybrids were used as the prototype, involved convergence of the two separately constructed moieties i.e. fosmidomycin and the quinoline moieties in a covalent linkage. The quinoline moiety was easily synthesized from the reaction of 4,7dichloroquinoline with 1,2-diamino ethane. The aminoquinoline so formed resulted in chloroquine-fosmidomycin hybrids 3.8 and 3.9 when reacted with halogenated FR900098 analogues. Antiplasmodial assays were conducted on the chloroquine-fosmidomycin hybrids and the halogenated fosmidomycin derivatives against the chloroquine resistant Gambian FCR-3 strain of P. falciparum. The most potent iodoacetyl fosmidomycin analogues 2.21 gave an IC50 value of 5.54 µM which is eight times more potent than the known antiplasmodial FR900098 which gave an IC50 value of 41.67 µM. All the halogenated FR900098 analogues showed better antiplasmodial activity than their non-halogenated derivatives. This indicated that the presence of halogens in the FR900098 analogues contributes to their biological Chapter 1 Literature review activity. The acetyl and propyl linked hybrids 3.8 and 3.9 showed potent antiplasmodial activity with IC50 values of 0.18 and 0.82 µM respectively. These were by far the most potent hybrids synthesized and provided leads for a new class of promising antimalarial agents. Preliminary E. coli DXR enzyme inhibition assays were carried out on the halogenated fosmidomycin analogues. The results showed good inhibition of the enzyme by the phosphonic acids of the chloroacetyl and chloropropyl analogues 2.1 and 2.2 respectively. Molecular modelling of the compounds on E. coli (PDB code: 2EGH) and P. falciparum (PDB code: 3AUA) DXR showed strong binding of the halogenated fosmidomycin analogues while the hybrids in the absence of docked NADPH showed minimum binding to the enzymes.
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Date Issued: 2012

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A phenomenological investigation of the beginning therapist's experience of the first session of psychotherapy with the first patient

- Allen, Jennifer Ann

Authors: Allen, Jennifer Ann
Date: 1987
Subjects: Uncatalogued
Language: English
Type: Master's theses , text
Identifier: http://hdl.handle.net/10962/193129 , vital:45301
Description: The aim of this project is to come to an understanding of how the situation of the first session of psychotherapy with the first patient is lived by the beginning therapist and what meaning this situation holds for him. The writer's interest in this phenomenon grew out of her own experience of this situation as a clinical Masters coursework student, an experience which was of important to the writer and meaningful still as a therapist in training. In dialogue with experienced therapists the importance of this situation was again made apparant. It was the opinion of these therapists that although for some the details of this experience had become dulled by time, what remained meaningful to them was that this experience was seen as the beginning of a project which remains important to them - they identified this situation as an important moment in the history of their development as psychotherapists. In the hope that the literature pertaining to psychotherapy would throw some light on this situation, the writer turned to a number of sources in this area to discover that no literature available to her elucidated this situation in a holistic manner. This led the writer to go back to the beginning therapists themselves so that they may speak for themselves of their experience of this situation. A phenomenological method of enquiry is implemented in this study as it renders the subject matter accessible to investigation, and allows it to reveal itself as it essentially is. This project is then an attempt to come to a general description of the beginning therapist's experience of the first session of psychotherapy with the first patient and thus to articulate the structure of the beginning therapist's lived situation (world) in this context. , Thesis (MA) -- Faculty of Humanities, Psychology, 1987
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Date Issued: 1987

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Self-reports on the effectiveness of psychotherapy with therapists-in-training: an 18-month follow-up study at a psychology training clinic

- Angus, Catherine Clare

Authors: Angus, Catherine Clare
Date: 1993
Subjects: Uncatalogued
Language: English
Type: Master's theses , text
Identifier: http://hdl.handle.net/10962/193069 , vital:45295
Description: The purpose of this study is to ascertain whether the clients who make use of the services of the Psychology Clinic at Rhodes University perceive the masters students being trained at the Clinic as providing adequate psychotherapy. Using a sample of 18 clients, who underwent psychotherapy at the Rhodes Psychology Clinic during 1990, a follow-up study was conducted to ascertain the perceived success of that psychotherapy. Those variables most pertinent to the outcome of psychotherapy are examined. The study uses both qualitative and quantitative methodology and shows that, overall, 89% of the clients who participated in this study perceived the psychotherapy at the Rhodes Psychology Clinic to be satisfactory. The study also highlights those factors which were perceived to be negative in the psychotherapeutic equation and it is hoped that the findings can be beneficial in planning more efficient services for the Clinic in the future. , Thesis (MA) -- Faculty of Humanities, Psychology, 1993
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Date Issued: 1993

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The construction of a swept-frequency polarimeter for observing decametric radiation from Jupiter

- Baker, Dirk E.

Authors: Baker, Dirk E.
Date: 1970-01
Subjects: Uncatalogued
Language: English
Type: Academic theses , Master's theses , text
Identifier: http://hdl.handle.net/10962/447507 , vital:74652
Description: This thesis describes the design and construction of a swept-frequency polarimeter for observing Jupiter’s decametric radiation in the frequency range from 15 to 45 MHz. The frequency band is tuned in two parts using two receivers for observing the left- and right-circular components of the radiation in the 15 to 26 MHz range and two receivers for observing the circular components in the 30 to 45 MHz range. The receivers are tuned electronically by means of varactor diodes and are of novel design in that they do not have any intermediate-frequency stages. The frequency band can be swept 10 times per second or 100 times per second. The antennas used for the polarimeter are helical beam antennas, two for each of the circular components in the 15 to 26 MHz range and two for the 30 to 45 MHz range. Model studies of the antennas were conducted to establish whether they have suitable characteristics for observing the polarisation of Jupiter’s decametric radiation over a wide frequency range. Many spectral records of Jupiter’s decametric radiation were obtained using a preliminary version of the swept-frequency receiver and a log-periodic dipole antenna. Some of the records are presented and one record which shows an interesting case of Faraday rotation is analysed. , Thesis (MSc) -- Faculty of Science, Physics, 1970
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Date Issued: 1970-01

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"Burnout" in children's home houseparents

- Bath, Peter John

Authors: Bath, Peter John
Date: 1983
Subjects: Uncatalogued
Language: English
Type: Master's theses , text
Identifier: http://hdl.handle.net/10962/193118 , vital:45300
Description: Aimed at replicating the results of an American study into "Burnout" in Group Home houseparents, this research had the following aims: 1) To ascertain the validity and reliability of the instrument used in the original study and presented as a "useful measure of burnout”. 2) To establish whether this line of research, within a highly problematic research field, can at present offer any guidelines in the resolution of the current staffing crisis faced by South African children's homes. 3} To describe more closely the burnout syndrome. 4) To study possible etiological factors within a local context. Sixty three houseparents completed questionaires and three independent measures of burnout were obtained. The results were regarded as having failed to replicate those of the original study. The reason for this was found to be the low validity of the original instrument. The main conclusion drawn was that the line of research adopted in the original study can offer only very tentative guidelines towards the resolution of the staffing crisis faced until such time as valid and reliable instruments to measure burnout have been developed. Many of the suggested relationships between situational variables and ones of personal characteristics were confirmed for the local population of houseparents. , Thesis (MSocSci) -- Faculty of Humanities, Psychology, 1983
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Date Issued: 1983

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