https://commons.ru.ac.za/vital/access/manager/Index ${session.getAttribute("locale")} 5 https://commons.ru.ac.za/vital/access/manager/Repository/vital:28068 Wed 31 May 2023 16:09:32 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28506 Wed 31 May 2023 15:41:19 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:27797 Wed 31 May 2023 14:45:14 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28394 Wed 17 May 2023 16:02:37 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:27609 Wed 17 May 2023 14:45:21 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:27975 Wed 17 May 2023 13:00:18 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28470 Wed 17 May 2023 11:50:13 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28048 Wed 17 May 2023 11:22:26 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28146 Wed 17 May 2023 08:48:14 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28235 Wed 15 Sep 2021 14:30:53 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28308 Wed 15 Sep 2021 12:38:53 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28200 Wed 15 Sep 2021 12:17:59 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:27236 Wed 15 Sep 2021 10:39:54 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28360 Wed 15 Sep 2021 09:36:53 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:26136 Wed 15 Sep 2021 08:47:54 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28087 Wed 15 Mar 2023 09:37:04 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28152 Wed 12 Oct 2022 11:48:48 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28139 Wed 03 May 2023 14:17:38 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:26641 Wed 03 May 2023 13:21:12 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28488 Wed 03 May 2023 13:07:26 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28508 Wed 03 May 2023 13:07:18 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28356 Tue 23 May 2023 12:25:11 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28195 Tue 23 May 2023 11:29:12 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28036 Tue 23 May 2023 09:23:13 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28052 Tue 16 May 2023 15:27:10 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28387 Tue 16 May 2023 14:59:05 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28199 Tue 16 May 2023 12:53:17 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28061 Tue 15 Aug 2023 11:05:18 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28347 Tue 14 Mar 2023 10:19:10 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28475 Tue 14 Mar 2023 08:48:02 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:27470 Tue 13 Jun 2023 09:02:08 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:27768 Tue 12 Oct 2021 15:53:29 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:27613 Tue 12 Oct 2021 15:50:19 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:27814 Tue 12 Oct 2021 15:49:22 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28019 Tue 12 Oct 2021 15:48:19 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28150 Tue 12 Oct 2021 15:47:54 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:27356 Tue 09 May 2023 15:48:03 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28482 Tue 09 May 2023 15:34:10 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:27809 Tue 09 May 2023 10:46:58 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28370 Tue 06 Jun 2023 12:39:11 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:26094 Thu 29 Sep 2022 14:21:25 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:27799 Thu 29 Sep 2022 14:18:31 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28410 Thu 25 May 2023 15:03:12 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:26998 Thu 25 May 2023 13:16:43 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28489 Thu 25 May 2023 13:00:06 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28038 Thu 25 May 2023 10:26:06 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:27751 Thu 19 Oct 2023 14:17:19 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28208 Thu 18 May 2023 15:27:00 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:27999 Thu 18 May 2023 14:24:18 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28212 Thu 18 May 2023 13:14:00 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:27615 Thu 18 May 2023 09:02:06 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:27805 Thu 13 Jul 2023 12:34:14 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28307 Thu 11 Apr 2024 19:25:38 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28430 Thu 09 Mar 2023 13:07:21 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28128 Thu 09 Mar 2023 13:00:25 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28428 Thu 09 Mar 2023 11:57:44 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28533 Thu 09 Mar 2023 09:44:15 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28355 Thu 06 Jul 2023 15:43:29 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:27998 Thu 06 Apr 2023 13:57:50 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28282 Thu 04 May 2023 14:38:03 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28413 Thu 04 May 2023 11:21:57 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28104 Thu 04 May 2023 09:22:59 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28149 Thu 04 May 2023 08:33:57 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:27791 Thu 01 Sep 2022 09:29:45 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28083 Thu 01 Jun 2023 15:41:15 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:26877 Thu 01 Jun 2023 11:15:19 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28216 Thu 01 Jun 2023 09:58:06 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28500 Thu 01 Jun 2023 09:02:09 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28434 Thu 01 Feb 2024 09:44:06 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28298 Sat 01 Jul 2023 12:28:13 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28465 Mon 29 May 2023 12:53:03 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28417 Mon 22 May 2023 15:47:55 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28062 Mon 22 May 2023 14:58:54 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28084 Mon 22 May 2023 08:40:56 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28063 90%) sequence similarity between BSCOMT and human soluble COMT (HSCOMT). BSCOMT was partially purified to 7.78 fold, 1.65% yield and had a specific activity of 0.052 U/mg. It had pH and temperature optima of 8.5 and 40oC, respectively. The Km, Vmax, Kcat and Kcat/Km towards esculetin methylation were respectively 1.475±0.130 pM, 0.0353±0.001 pmol/ml/min, 1.748 x 10-2±5.0x10-4 min-1 and 1.18x10-2 M-1. min-1. HSCOMT was expressed in Escherichia coli BL21(DE3) which showed optimal activity for esculetin methylation at pH and temperature of 7.0 and 30°C, respectively. It was purified to 5.62 fold, 22.6% yield with a specific activity of 3.85 U/mg. HSCOMT kinetic plots, upon incubation of the reaction mixture at 30°C for 5 min before addition of SAM was hyperbolic with Km, Vmax, Kcat and Kcat/Km values of 1.79 pM, 0.412 pmol/ml/min, 2.08 min-1 and 1.165 M-1. min-1, respectively. AuNPs and AgNPs showed a concentration dependent inhibition of HSCOMT activity upon increasing the 5 min incubation time to 1 h. Interestingly, HSCOMT kinetics, with 1 h incubation at 30°C, showed a sigmoidal curve, as well as increased activity. Incubation of the reaction mixture in the presence of 60 pM AuNPs and/or AgNPs for 1 hreversed the observed sigmoidal to a hyperbolic curve, with kinetic parameters comparable to those of 5 min incubation. SDS-PAGE analyses of HSCOMT after the kinetic experiments showed the enzyme incubated for 5 min as a monomer, while that which was incubated for 1 h migrated substantially as dimer. However, the HSCOMT incubated for 1 h in the presence of 60 pM AuNPs and/or AgNPs migrated as a monomer. This indicated that the extension of the incubation period allowed the dimerization of HSCOMT, which exhibited sigmoidal kinetics and higher activity. The presence of NPs impeded the HSCOMT dimerization which decreased the activity. Varying the concentration of SAM suggested that SAM had an allosteric modulatory effect on HSCOMT. Absorption spectroscopy indicated adsorption of HSCOMT on the gold and silver NP surfaces and the formation of NPs-HSCOMT corona. Fluorescence spectroscopy showed that the interaction of HSCOMT with both gold and silver NPs was governed by a static quenching mechanism, implying the formation of a non-fluorescent fluorophore-NP complex at the ground state. Further fluorometric analyses indicated that both gold and silver NPs had contact with Trp143; that the interactions were spontaneous and were driven by electrostatic interactions. Fourier transform infrared spectroscopic studies showed the adsorption of HSCOMT of the NPs surfaces to cause relaxation of the enzyme’s B-sheet structures. Molecular docking studies indicated involvement of largely hydrophilic amino acids, with the interacting distances of less than 3.5A. These findings signify the potential of nanotechnology in the control of COMT catalytic activity for the management of the COMT-related disorders.]]> Mon 13 Mar 2023 14:31:23 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28145 Mon 13 Mar 2023 12:53:24 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28421 85 % isoniazid released at 24 h, implying that the majority of encapsulated isoniazid would be available for absorption. The manufacturing process resulted in the production of hard spherical particles and particle size analysis revealed that the microspheres ranged between 415.76 ± 76.93 μm and 903.35 ± 197.10 μm in diameter. The microspheres exhibited excellent flow properties attributed to the spherical nature of particles. Carr‟s index (CI) was 4.934 ± 0.775 % and the Hausner ratio (HR) was 1.148 ± 0.033 indicating good packability of the microspheres that would help in achieving weight and content uniformity of capsule dosage units. The manufacturing process however produced a low % yield suggesting that scale up difficulties may be encountered. However the high encapsulation efficiency observed may counter the challenges associated with the low yield. The DSC thermograms and FT Raman spectra of 1:1 mixtures of isoniazid, excipients and the microspheres did not reveal any potential detrimental interactions. Microporous floating sustained release microspheres for the delivery of rifampicin in the stomach have been successfully manufactured using emulsification and a diffusion/evaporation process. A novel approach using solvent mixture of acetone and dichloromethane that has not been reported for the manufacture of rifampicin microspheres was successfully used and resulted in the formation of a stable emulsion and the manufacture of rifampicin-loaded microspheres with uniform characteristics. In addition the manufacturing process was shorter than most other reported methods. A Box-Behnken experimental design was successfully used to study the influence of ethylcellulose, Eudragit® RLPO and d-glucose content on the floating properties, encapsulation efficiency and % yield of microspheres. The optimised formulation did not yield desired floating characteristics as the % buoyancy was low and floating lag times were high. The optimised formulation was modified by addition of NaHCO3 to increase the % buoyancy and reduce the floating lag time. Rifampicin release from the microspheres of the modified batch was 87.10 % at 12 h and the microspheres exhibited a % buoyancy of 87.66 ± 1.28 % (n = 6) and floating lag time of 15 ± 3.2 (n = 6) seconds. The microspheres remained buoyant for up to 12 h and an encapsulation efficiency of 88.26 ± 1.25 % was achieved. SEM images of microspheres following exposure to dissolution fluid revealed that the microspheres had numerous pores on their surface. The mean particle size distribution ranged between 423.19 ± 121.86 μm to 620.07 ± 102.67 μm. The microspheres exhibited similar flow characteristics to isoniazid microspheres with a CI of 1.422 ± 0.074 %, and HR of 1.034 ± 0.002. The excellent flow characteristics indicate that filling of the microspheres into hard gelatin capsules was unlikely to pose a challenge in respect of producing a product with uniform content. Rifampicin-excipient compatibility studies did not reveal any potential or significant interactions suggesting that the excipients used for the manufacture of the microspheres were compatible, although long term stability studies would be required to ascertain this is, indeed the case. The microporous floating sustained release microspheres manufactured in these studies has the potential to increase the bioavailability of rifampicin as they may be retained in the stomach where the solubility of rifampicin is high and from which absorption is best achieved. The degradation of rifampicin after 12 h dissolution testing in pH 1.2 0.1 M HCl in the presence of isoniazid gastric-resistant sustained release microspheres was only 4.44%. These results indicate that the degradation of rifampicin in the presence of isoniazid in acidic media can be overcome by encapsulation of both active pharmaceutical ingredients in a manner that ensure release in different segments of the gastrointestinal tract. The use of sustained release microporous gastroretentive rifampicin microspheres in combination with sustained release isoniazid gastric-resistant microspheres revealed that accelerated degradation of rifampicin in the presence of isoniazid is reduced significantly when using this approach and a FDC of rifampicin and isoniazid microspheres has the potential to improve the bioavailability of rifampicin thereby enhancing therapeutic outcomes. In vivo studies would be required to confirm the potential benefits of using this approach to deliver rifampicin in combination with isoniazid.]]> Mon 13 Mar 2023 11:57:13 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28492 Mon 10 Oct 2022 14:26:28 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28065 Mon 05 Jun 2023 15:41:21 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28057 Mon 05 Jun 2023 15:06:28 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28099 Mon 05 Jun 2023 13:28:12 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:27756 Mon 05 Jun 2023 09:23:18 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:27629 Mon 03 Jul 2023 14:13:59 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28090 Fri 26 May 2023 11:09:43 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:27790 Fri 19 May 2023 12:39:03 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28484 Fri 19 May 2023 11:29:02 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:27408 Fri 19 May 2023 10:05:04 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:27617 Fri 19 May 2023 09:37:03 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28228 Fri 17 Sep 2021 14:51:46 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28388 Fri 17 Sep 2021 12:45:46 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28043 Fri 17 Sep 2021 11:42:47 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28448 Fri 17 Sep 2021 10:25:45 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:27038 Fri 17 Sep 2021 10:11:50 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28130 Fri 10 Mar 2023 15:27:16 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28297 Fri 10 Mar 2023 12:46:15 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:45423 Fri 10 Mar 2023 10:05:17 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28323 Fri 07 Jul 2023 06:57:12 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28496 Fri 07 Jul 2023 05:33:04 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28034 Fri 02 Jun 2023 11:43:09 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:28070 Fri 02 Jun 2023 09:09:15 SAST ]]>