/library/oar/handle/123456789/66080 2025-12-23T11:36:32Z /library/oar/handle/123456789/73396 Title: Structure and function of human Mn(Fe)SOD containing iron in the active site Abstract: MnSOD is a mitochondrial protein that protects the cell from copious amounts of superoxide radicals that are generated by the electron transport chain in the healthy individual. It also plays an important role in free radical detoxification during pathologic state such as chronic inflammation and infection. As a metalloenzyme, MnSOD is only functional with manganese as the active site cofactor. Under certain cellular conditions, iron may replace manganese in the active site and the protein may serve as an iron reservoir in the mitochondria. Previous research carried out on the sub-cloned C. elegans MnSOD mutant, hMn(Fe)SOD [Q142H] has shown that a substitution of an active site residue was sufficient to change the metal specificity of the protein (Hunter et al., 2018). To the same end, the mutant hMnSOD Q143H was expressed in competent RosettaTM cells that were grown in minimal media supplemented with controlled quantities of selected metal salts. Expressed protein, induced by IPTG, were purified by MCAC and quantified using BCA and direct A280 measurements. CD structural probing revealed conservation of secondary structure integrity with increased stability in iron substituted mutants. The structure of hMnSOD Q143H, as refined through crystallographic diffraction data, was also modelled with electron density maps. Enzyme specific metal activity was reduced when compared to WT hMnSOD with activity for hMnSOD Q143H measured at 144 ±19 U mg−1 and 210 ±45 U mg−1 whereas for substituted mutants hMn(Fe)SOD Q143H activity was measured at 688 ±62 U mg−1. hMnSOD wild-type exhibited an activity of 9481 ±411 U mg−1. Metal occupancy for iron-substituted mutants was at 66% with Mn content for hMnSOD Q143H was measured at 70% and 99%, respectively. Therefore, hMn(Fe)SOD Q143H exhibited a shift in iron-supported activity but at the detriment of a 93% loss in catalytic function. Description: M.SC.BIOCHEMISTRY 2020-01-01T00:00:00Z /library/oar/handle/123456789/73391 Title: Heavy metals in Maltese agricultural soil Abstract: Soil pollution has increased over the last few decades due to anthropogenic sources. Heavy metal pollution has been of great concern since it has been noted that these contaminants have entered our food chain. High concentration of heavy metals can adversely affect the health of the public wellbeing. The aim of the study was to evaluate whether i) heavy metals found in soil are present in high amounts; ii) heavy metals found in soil are present differently across Malta and Gozo; iii) there are soil limits regulating heavy metals. The soil samples were analysed with an X-Ray Fluorescence Spectrometer using the sample cup method. The method of analyses was validated by comparing it to the results obtained in an external laboratory. The samples were analysed to determine the concentration of heavy metals, namely aluminium, vanadium, chromium, cobalt, manganese, nickel, copper, zinc, molybdenum, arsenic, silver, cadmium, selenium, mercury and lead in soil. Samples were collected from five districts in Malta and from Gozo. A total of 103 samples were collected and analysed, out of which two samples were collected from organic farms and used as controls. Samples were analysed in triplicate and an average was calculated. Most of the soil samples tested showed that the heavy metals found in the soil were observed to be present at higher concentrations in the South-Eastern District and the Southern Harbour. Concentrations of the heavy metals tested were mapped out according to district and localities. The highest concentration of aluminium was found in the Western District at 38106.00 mg/kg. The highest concentration of lead was observed in the Southern Harbour and was statistically significantly (ρ-value<0.05) different from the rest of the districts with a concentration of 249.51 mg/kg. Other metals that were found at their highest concentrations in the Southern Harbour, were copper at 95.15 mg/kg and zinc at 251.33 mg/kg. The heavy metals vanadium at 64.25 mg/kg, chromium at 45.93 mg/kg, manganese at 586.67 mg/kg, nickel at 21.90 mg/kg and selenium at 15.51 mg/kg, to be observed at their highest concentrations in the South-Eastern District when compared to the other districts. The highest concentrations of molybdenum at 12.09 mg/kg, arsenic at 7.93 mg/kg and cadmium at 30.10 mg/kg were observed in the Northern District. Cobalt was seen with the highest concentration in the Gozo and Comino District, at 15.83 mg/kg. The Finland and Dutch standards were used to compare the results observed. Lead was found to exceed the threshold limits of the Finland standard which is 60 mg/kg and the Dutch standard which is 85 mg/kg. Cadmium was observed to exceed the threshold value of the Finland standard which is 1 mg/kg and the Dutch standard which is 0.8 mg/kg. The Finland standard concentration of arsenic is 1 mg/kg, which was much lower than the concentration observed in the Northern District. Zinc was found to exceed the threshold limits of the Finland standard which is 200 mg/kg and the Dutch standard value which is 50 mg/kg. The lower concentration of heavy metals observed in organic farms may be attributed to the lack of chemical use whereby instead biodiversity is applied to aid in pest and weed reduction. There is a need for the implementation of methods to address the high concentrations of heavy metals. Such methods which can be applied include phytoremediation, intercropping and organic farming. Description: M.SC.BIOCHEMISTRY 2020-01-01T00:00:00Z /library/oar/handle/123456789/67087 Title: Effect of ethosuximide (ETX) on neuropsychiatric comorbidities in absence seizures Abstract: This study focused on the effects of the antiepileptic drug ethosuximide (ETX), at a dose of 200 mg/kg, on the psychiatric comorbidities in childhood absence epilepsy. The psychiatric comorbidity of interest was anxiety since ETX is said to exhibit antianxiety effects. Therefore, ETX was studied with respect to its anxiolytic or anxiogenic effects on three strains of rats: GAERS as the epileptic rats, NEC being the nonepileptic control and Wistar as a second control. The behaviour of rats reflects their anxiety levels, and thus, changes in behaviour were seen as an increase or decrease in anxiety. Rats were divided into two groups, vehicle and treatment group, and were administered with vehicle solution or ETX, accordingly. Each group was further divided into two groups: those undergoing hole-board (HB) test and those undergoing elevated plus-maze (EPM) test. During these tests, rats were recorded, and the video recordings were used to analyse the behavioural parameters of each test. The data obtained was used to carry out two-way ANOVA and Sidak’s post hoc test for multiple comparisons. These statistical tests determined the significance of the behavioural changes observed, following the administration of ETX or vehicle. They also showed whether ETX had varying anxiolytic effects on the different strains. The results showed that the anxiolytic effects of ETX were more prominent in GAERS, being epileptic, than in any of the other non-epileptic strains. The research conducted is part of an ongoing effort to find better treatments for childhood absence epilepsy and the accompanying psychiatric comorbidities. Description: B.SC.MEDICAL BIOCHEMISTRY 2020-01-01T00:00:00Z /library/oar/handle/123456789/67085 Title: Role of cannabidiol in neuropsychiatric comorbidities in absence seizures Abstract: Available anti-epileptic drugs are efficient enough to block seizures but do not treat comorbid psychiatric conditions such as anxiety, thus resulting in possible symptom aggravation. Since cannabidiol (CBD) has been recently approved in the USA and Europe for the treatment of two rare childhood types of epilepsy, and it is known to have anxiolytic effects this study aimed to evaluate its effects on anxiety in an animal model of childhood absence epilepsy (CAE) at a dose of 100 mg/kg. We used a polygenic model of CAE, the Genetic Absence Epilepsy Rats from Strasburg (GAERS), comparing with its non-epileptic control (NEC) rats and the original outbred strain, Wistar rats. Rats were injected with CBD (100 mg/kg) or vehicle prior to undergoing behavioural testing, i.e., the Hole-Board Test and the Elevated Plus Maze. It was observed that 100 mg/kg of CBD induced an anxiogenic effect in GAERS strain, with minimal effects on NEC and Wistar, contradicting the available evidence. This is possibly due to i) the high dose of CBD used here, ii) an effect of the vehicle considering that iii) GAERS rats used in control conditions showed a less anxious profile of those compared to other studies also from the same laboratory. This indicates that appropriate dose-response studies need to be done using a different vehicle to find an optimum dosage. Comparisons to other rat models would also be envisaged. Description: B.SC.MEDICAL BIOCHEMISTRY 2020-01-01T00:00:00Z