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Fulltext Meckel's diverticulum and indications for resection

Rahim R

Clin Case Rep, 2020 Dec;8(12):3588-3589.
PMID: 33363991 DOI: 10.1002/ccr3.3297

Meckel's diverticulum (MD) is a rare congenital abnormality. Not all MD require resection. MD is resected when it is symptomatic; when it causes perforation, bleeding, or intestinal obstruction; or when malignancy is confirmed or suspected.
Fulltext Small scale imaging using ultrasonic tomography

Zakaria, Z., Fazalul Rahiman, M.H., Abdul Rahim, R., Megat Ali, M.S.A., Baharuddin, M.Y., Jahidin, A.H.

Journal of Nuclear and Related Technologies, 2009;2009(1):266-281.
MyJurnal

Ultrasound technology progressed through the 1960’s from simple A-mode and B-mode scans to today’s M-mode and Doppler two dimensional (2-D) and even three dimensional (3-D) systems. Modern ultrasound imaging has its roots in sonar technology after it was first described by Lord John Rayleigh over 100 years ago on the interaction of acoustic waves with media. Tomography technique was developed as a diagnostic tool in the medical area since the early of 1970’s. This research initially focused on how to retrieve a cross sectional images from living or non-living things. After a decade, the application of tomography systems span into the industrial area. However, the long exposure time of medical radiation-based method cannot tolerate the dynamic changes in industrial process two phase liquid/gas flow system.. An alternative system such as a process tomography system, can give information on the nature of the flow regime characteristic. The overall aim of this paper is to investigate the use of a small scale ultrasonic tomography method based on ultrasonic transmission mode tomography for online monitoring of liquid/gas flow in pipe/vessel system through ultrasonic transceivers application. This non-invasive technique applied sixteen transceivers as the sensing elements to cover the pipe/vessel cross section. The paper also details the transceivers selection criteria, hardware setup, the electronic measurement circuit and also the image reconstruction algorithm applied. The system was found capable of visualizing the internal characteristics and provides the concentration profile for the corresponding liquid and gas phases.
Fulltext Optical tomography: real time image reconstruction for various flow regimes in gravity flow conveyor

Abdul Rahim, R., Pang, J.F., Chan, K.S., Leong, L.C., Fazalul Rahiman, M.H.

ASM Science Journal, 2007;1(1):27-36.
MyJurnal

In this study, real-time imaging was monitored for flowing solid particles when various baffles were created to block certain areas of the pipe. The generated flow regimes were full-flow, three-quarter-flow, half-flow and quarter-flow. A vertical pneumatic conveyor was designed to hold a 85 mm inner diameter pipeline. The four projection optical tomography systems used, applied the parallel beam projection approach and use infrared light sources so that the sensor was free of noise from the surrounding visible light source. The two orthogonal and two rectilinear projections were axial, but ideally they should have been in the same layer. The sensor readings could be related to the varying light intensity effects of the dropping particles and were used to provide cross-sectional distribution information for the conveyor. By using computer programming, the information was reconstructed to produce coloured images and concentration was obtained by reference to a colour code. The results obtained from this study showed how imaged flow followed the artificial flow regime. This study could benefit industrial production lines in maintaining the desired flow rates.
Fulltext The effect of flaxseed extract on skin elasticity of the healing wound in rabbits.

Abdul Jabbar O, Kashmoola MA, Mustafa Al-Ahmad BE, Mokhtar KI, Muhammad N, Abdul Rahim R, et al.

IIUM Medical Journal Malaysia, 2019;18(1):5-12.
MyJurnal

Management of disturbed wounds, large skin defects and the areas where skin tension precludes wound closure is of high clinical importance. Healing in wounds occurs through epithelization and contraction processes (second-intentions healing) that may result in certain undesirable complications including keloid and formation of a fragile epithelial layer.Materials and methods: 27 white New Zealand rabbit included in this study divided into 3 groups; one group of 9 rabbits received Flaxseed gel topically for three time intervals (1, 7, and 14 days); a second group received Fucidin cream as positive control, while a third group has not received any treatment as negative control, Skin elasticity measurements were performed using the DermaLab system. Results: Throughout the study, skin elasticity was significantly greater in Flaxseed group than in others. Flaxseed decrease elasticity value from (3.46 ± 2.05). Hence, Young's modulus of skin elasticity in flaxseed group was (2.46 ± 1.02) after 14 days (p = 0.003), while no significant differences were evident in both Fucidin group (1.16 ± 0.77) and non-treated group (1.86 ± 1.40) (p = 0.019), accordingly flaxseed extract more reproducible than other groups demonstrating comparable efficacy in skin elasticity and distensibility.Conclusions: This study showed the therapeutic effect of flaxseed on biologic tissue. Elasticity evaluation demonstrated increased density and firmness in the network of collagen fibers in the dermis and subcutis during wound healing process promise in generating therapeutic gel to be used in wound healing process.
Fulltext Neural network and principal component regression in non-destructive soluble solids content assessment: a comparison

Chia KS, Abdul Rahim H, Abdul Rahim R

J Zhejiang Univ Sci B, 2012 Feb;13(2):145-51.
PMID: 22302428 DOI: 10.1631/jzus.B11c0150

Visible and near infrared spectroscopy is a non-destructive, green, and rapid technology that can be utilized to estimate the components of interest without conditioning it, as compared with classical analytical methods. The objective of this paper is to compare the performance of artificial neural network (ANN) (a nonlinear model) and principal component regression (PCR) (a linear model) based on visible and shortwave near infrared (VIS-SWNIR) (400-1000 nm) spectra in the non-destructive soluble solids content measurement of an apple. First, we used multiplicative scattering correction to pre-process the spectral data. Second, PCR was applied to estimate the optimal number of input variables. Third, the input variables with an optimal amount were used as the inputs of both multiple linear regression and ANN models. The initial weights and the number of hidden neurons were adjusted to optimize the performance of ANN. Findings suggest that the predictive performance of ANN with two hidden neurons outperforms that of PCR.
Prevalence of Listeria spp and Listeria monocytogenes in meat and fermented fish in Malaysia

Hassan Z, Purwati E, Radu S, Rahim RA, Rusul G

Southeast Asian J Trop Med Public Health, 2001 Jun;32(2):402-7.
PMID: 11556596

Fermented fish and meat samples were purchased from supermarket and wet market for microbiological analysis of Listeria species and Listeria monocytogenes contamination. Listeria species were isolated from 17 (73.9%) of 23 samples of imported frozen beef, 10 (43.5%) of the 23 samples of local beef and 14 (56%) of the 25 samples of fermented fish from wet market. Listeria monocytogenes occurred in 15 (75%) of the frozen beef samples, 6 (30.4%) of the 23 samples of local meat and 3 (12%) of the 25 samples from fermented fish. Listeria species was not isolated from any of the 23 samples of imported frozen beef from supermarket and from the 5 samples of buffalo meat examined. This highlights the possibility of Listeria spp or L. monocytogenes to persist in meat and fermented fish in wet market and raises the problem of illness due to the handling and consumption of Listeria-contaminated meat or fermented fish are likely as evidence by the high contamination rates of samples sold at the wet market.
Fulltext Molecular characterization of a recombinant manganese superoxide dismutase from Lactococcus lactis M4

Tan BH, Chor Leow T, Foo HL, Abdul Rahim R

Biomed Res Int, 2014;2014:469298.
PMID: 24592392 DOI: 10.1155/2014/469298

A superoxide dismutase (SOD) gene of Lactococcus lactis M4 was cloned and expressed in a prokaryotic system. Sequence analysis revealed an open reading frame of 621 bp which codes for 206 amino acid residues. Expression of sodA under T7 promoter exhibited a specific activity of 4967 U/mg when induced with 1 mM of isopropyl-β-D-thiogalactopyranoside. The recombinant SOD was purified to homogeneity by immobilised metal affinity chromatography and Superose 12 gel filtration chromatography. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and western blot analyses of the recombinant SOD detected a molecular mass of approximately 27 kDa. However, the SOD was in dimer form as revealed by gel filtration chromatography. The purified recombinant enzyme had a pI of 4.5 and exhibited maximal activity at 25°C and pH 7.2. It was stable up to 45°C. The insensitivity of this lactococcal SOD to cyanide and hydrogen peroxide established that it was a MnSOD. Although it has 98% homology to SOD of L. lactis IL1403, this is the first elucidated structure of lactococcal SOD revealing active sites containing the catalytic manganese coordinated by four ligands (H-27, H-82, D-168, and H-172).
Fulltext Purification and Characterization of a Thermostable Lipase from Geobacillus thermodenitrificans IBRL-nra

Balan A, Ibrahim D, Abdul Rahim R, Ahmad Rashid FA

Enzyme Res, 2012;2012:987523.
PMID: 23198138 DOI: 10.1155/2012/987523

Thermostable lipase from Geobacillus thermodenitrificans IBRL-nra was purified and characterized. The production of thermostable lipase from Geobacillus thermodenitrificans IBRL-nra was carried out in a shake-flask system at 65°C in cultivation medium containing; glucose 1.0% (w/v); yeast extract 1.25% (w/v); NaCl 0.45% (w/v) olive oil 0.1% (v/v) with agitation of 200 rpm for 24 hours. The extracted extracellular crude thermostable lipase was purified to homogeneity by using ultrafiltration, Heparin-affinity chromatography, and Sephadex G-100 gel-filtration chromatography by 34 times with a final yield of 9%. The molecular weight of the purified enzyme was estimated to be 30 kDa after SDS-PAGE analysis. The optimal temperature for thermostable lipase was 65°C and it retained its initial activity for 3 hours. Thermostable lipase activity was highest at pH 7.0 and stable for 16 hours at this pH at 65°C. Thermostable lipase showed elevated activity when pretreated with BaCl(2), CaCl(2), and KCl with 112%, 108%, and 106%, respectively. Lipase hydrolyzed tripalmitin (C16) and olive oil with optimal activity (100%) compared to other substrates.
A rare case of intussusception associated with metastasized small cell carcinoma of lung

Jarmin R, Azman A, Rahim R, Kosai NR, Das S

Acta Med Iran, 2012;50(11):782-4.
PMID: 23292632

Intussusception is common cause of bowel obstruction in the paediatric age group compared to the elderly population. Many times, the diagnosis may be difficult because of asymptomatic nature of this bowel disorder. We hereby describe the case of a 75-year-old male who presented with lethargy, weakness, loss of movement in the joints and was found to be anemic. The haemoglobin level was low so he was transfused with packed cells. On gastrointestinal (GI) endoscopy, upper GI bleed was observed. A mass was observed beyond ampulla at the 2nd and 3rd part of the duodenal junction. Computerized tomography (CT) scan also showed a mass at the head of pancreas and the lesion at the left lung. In view of persistent bleed, 'Whipple's procedure' was performed. Histopathological examination showed small cell carcinoma of the lungs with metastasis to the pancreas and the jejunum. We here discuss the case of intussusception with intestinal metastasis which presented with gastrointestinal bleeding.
Lensed optical fiber sensors for on-line measurement of flow

Ibrahim S, Green RG, Dutton K, Abdul Rahim R

ISA Trans, 2002 Jan;41(1):13-8.
PMID: 12014798

This paper describes a system using lensed optical fiber sensors that are arranged in the form of two orthogonal projections. The sensors are placed around a process vessel for upstream and downstream measurements. The purpose of the system is for on-line monitoring of particles and droplets being conveyed by a fluid. The lenses were constructed using a custom heating fixture. The fixture enables the lenses to be constructed with similar radii resulting in identical characteristics with minimum differences in transmitted intensity and emission angle. By collimating radiation from two halogen bulbs, radiation can be obtained by the sensors with radiation intensity related to the nature of the media. Each sensor interrogates a finite section of the measurement section. Each sensor provides a view. Parallel sensors provide a projection. Signal processing is carried out on the measured data in the time and frequency domains to investigate the latent information present in the flow signals.
Fulltext Effects of lysine and methionine in a low crude protein diet on the growth performance and gene expression of immunity genes in broilers

Lee CY, Song AA, Loh TC, Abdul Rahim R

Poult Sci, 2020 Jun;99(6):2916-2925.
PMID: 32475425 DOI: 10.1016/j.psj.2020.03.013

Globally, the poultry industry is 1 of the most advanced livestock industries. Feed contributes to the biggest proportion (65-70%) of the production cost. Most feed ingredients in Malaysia are imported, which contributes to the high food bill annually, and alternative feed formulation may help decrease the cost of poultry feed. Feed formulation are improved to efficiently meet the dietary requirements of the broilers and 1 of the ways is by reducing the level of crude protein in the diet while supplementing essential amino acids. In this study, the effects of methionine and lysine, which are the 2 most limiting amino acids in the chicken diet, were supplemented in a low crude protein diet, and its effects on the growth and expression of immunity genes such as MUC2, SLC, GAL6, and LEAP-2 were studied. A total of 300 Cobb500 broilers were tested with 10 different dietary treatments. Experimental treatment diets consist of high, standard, and low levels of methionine and lysine in the diet with reduced crude protein. The control group consists of diet with standard levels of lysine, methionine, and crude protein as recommended for Cobb500 broilers. Ribonucleic acid was extracted from the jejunum, spleen, and liver for gene expression analysis which was performed with real-time polymerase chain reaction using SYBR Green chemistry. Results of the growth performance at 6 wk showed improved feed conversion ratio when lysine was increased by 0.2% in a low crude protein diet at 1.96 ± 0.11. Gene expression of MUC2 gene in the jejunum showed a significant increase across all experimental diets with the treatment with higher lysine in low crude protein diet with the highest increase of 3.8 times as compared with the control diet. The other genes expressed in the spleen and liver were mostly downregulated. It was concluded that supplementation of high lysine with standard methionine in a low crude protein diet performed better in terms of lowest feed conversion ratio and high upregulation of MUC2 gene.
Fulltext Surface display of respiratory syncytial virus glycoproteins in Lactococcus lactis NZ9000

Lim SH, Jahanshiri F, Rahim RA, Sekawi Z, Yusoff K

Lett Appl Microbiol, 2010 Dec;51(6):658-64.
PMID: 20973806 DOI: 10.1111/j.1472-765X.2010.02950.x

A system for displaying heterologous respiratory syncytial virus (RSV) glycoproteins on the surface of Lactococcus lactis NZ9000 was developed.
Fulltext Liquid-Based Reconfigurable Antenna Technology: Recent Developments, Challenges and Future

Abu Bakar H, Abd Rahim R, Soh PJ, Akkaraekthalin P

Sensors (Basel), 2021 Jan 26;21(3).
PMID: 33530534 DOI: 10.3390/s21030827

Advances in reconfigurable liquid-based reconfigurable antennas are enabling new possibilities to fulfil the requirements of more advanced wireless communication systems. In this review, a comparative analysis of various state-of-the-art concepts and techniques for designing reconfigurable antennas using liquid is presented. First, the electrical properties of different liquids at room temperature commonly used in reconfigurable antennas are identified. This is followed by a discussion of various liquid actuation techniques in enabling high frequency reconfigurability. Next, the liquid-based reconfigurable antennas in literature used to achieve the different types of reconfiguration will be critically reviewed. These include frequency-, polarization-, radiation pattern-, and compound reconfigurability. The current concepts of liquid-based reconfigurable antennas can be classified broadly into three basic approaches: altering the physical (and electrical) dimensions of antennas using liquid; applying liquid-based sections as reactive loads; implementation of liquids as dielectric resonators. Each concept and their design approaches will be examined, outlining their benefits, limitations, and possible future improvements.
Global Transcriptome Analysis of Gracilaria changii (Rhodophyta) in Response to Agarolytic Enzyme and Bacterium

Lim EL, Siow RS, Abdul Rahim R, Ho CL

Mar Biotechnol (NY), 2016 Apr;18(2):189-200.
PMID: 26631182 DOI: 10.1007/s10126-015-9680-6

Many bacterial epiphytes of agar-producing seaweeds secrete agarase that degrade algal cell wall matrix into oligoagars which elicit defense-related responses in the hosts. The molecular defense responses of red seaweeds are largely unknown. In this study, we surveyed the defense-related transcripts of an agarophyte, Gracilaria changii, treated with β-agarase through next generation sequencing (NGS). We also compared the defense responses of seaweed elicited by agarase with those elicited by an agarolytic bacterium isolated from seaweed, by profiling the expression of defense-related genes using quantitative reverse transcription real-time PCR (qRT-PCR). NGS detected a total of 391 differentially expressed genes (DEGs) with a higher abundance (>2-fold change with a p value <0.001) in the agarase-treated transcriptome compared to that of the non-treated G. changii. Among these DEGs were genes related to signaling, bromoperoxidation, heme peroxidation, production of aromatic amino acids, chorismate, and jasmonic acid. On the other hand, the genes encoding a superoxide-generating NADPH oxidase and related to photosynthesis were downregulated. The expression of these DEGs was further corroborated by qRT-PCR results which showed more than 90 % accuracy. A comprehensive analysis of their gene expression profiles between 1 and 24 h post treatments (hpt) revealed that most of the genes analyzed were consistently upregulated or downregulated by both agarase and agarolytic bacterial treatments, indicating that the defense responses induced by both treatments are highly similar except for genes encoding vanadium bromoperoxidase and animal heme peroxidase. Our study has provided the first glimpse of the molecular defense responses of G. changii to agarase and agarolytic bacterial treatments.
Determination and Quantification of the Vinblastine Content in Purple, Red, and White Catharanthus Roseus Leaves Using RP-HPLC Method

Abdul Rahim R, Ahmad NH, Al Azzam KM, Mat I

Adv Pharm Bull, 2018 Mar;8(1):157-161.
PMID: 29670851 DOI: 10.15171/apb.2018.019

Purpose:
To determine and quantify vinblastine in different varieties of Catharanthus roseus using reversed-phase HPLC method.
Methods:
The liquid chromatographic separation was performed using a reversed phase C18, Microsorb - MV column (250 mm x 4.6 mm, 5 µm) at room temperature and eluted with a mobile phase containing methanol - phosphate buffer (5 mM, pH 6.0) - acetonitrile with different proportion gradient elution at a flow rate of 2.0 mL min-1 and detection at 254 nm.
Results:
The HPLC method was utilized for the quantification of vinblastine in purple, red and white varieties of Catharanthus roseus leaves. The separation was achieved in less than 8 min. The peak confirmation was done based on the retention times and UV spectra of the reference substance. The method was validated with respect to linearity, precision, recovery, limit of detection and quantification. Results showed that the purple variety gives 1.2 and 1.5 times more vinblastine concentration compared to the white and pink varieties, respectively.
Conclusion:
The obtained results from different varieties are thus useful for the purpose of vinblastine production from Catharanthus roseus plant.
Hydrogel beads bio-nanocomposite based on Kappa-Carrageenan and green synthesized silver nanoparticles for biomedical applications

Azizi S, Mohamad R, Abdul Rahim R, Mohammadinejad R, Bin Ariff A

Int J Biol Macromol, 2017 Nov;104(Pt A):423-431.
PMID: 28591593 DOI: 10.1016/j.ijbiomac.2017.06.010

This paper describes the fabrication and characterization of bio-nanocomposite hydrogel beads based on Kappa-Carrageenan (κ-Carrageenan) and bio-synthesized silver nanoparticles (Ag-NPs). The silver nanoparticles were prepared in aqueous Citrullus colocynthis seed extract as both reducing and capping agent. Cross-linked κ-Carrageenan/Ag-NPs hydrogel beads were prepared using potassium chloride as the cross-linker. The hydrogel beads were characterized using XRD and FESEM. Moreover, swelling property of the hydrogel beads was investigated. The Ag release profile of the hydrogels was obtained by fitting the experimental data to power law equation. The direct visualization of the green synthesized Ag-NPs using TEM shows particle size in the range of 23±2nm. The bio-nanocomposite hydrogels showed lesser swelling behavior in comparison with pure κ-Carrageenan hydrogel. Regardless the slow Ag release, κ-Carrageenan/Ag-NPs presented good antibacterial activities against Staphylococcus aureus, Methicilin Resistant Staphylococcus aurous, Peseudomonas aeruginosa and Escherichia coli with maximum zones of inhibition 11±2mm. Cytotoxicity study showed that the bio-nanocomposite hydrogels with non-toxic effect of concentration below 1000μg/mL have great pharmacological potential and a suitable level of safety for use in the biological systems.
Dielectrophoresis applications in biomedical field and future perspectives in biomedical technology

Mohd Maidin NN, Buyong MR, A Rahim R, Mohamed MA

Electrophoresis, 2021 10;42(20):2033-2059.
PMID: 34346062 DOI: 10.1002/elps.202100043

Dielectrophoresis (DEP) is a technique to manipulate trajectories of polarisable particles in nonuniform electric fields by utilizing unique dielectric properties. The manipulation of a cell using DEP has been demonstrated in various modes, thereby indicating potential applications in the biomedical field. In this review, recent DEP applications in the biomedical field are discussed. This review is intended to highlight research work that shows significant approach related to DEP application in biomedical field reported between 2016 and 2020. First, single-shell model and multiple-shell model of cells are introduced. Current device structures and recently introduced electrode patterns for DEP applications are discussed. Second, the biomedical uses of DEP in liquid biopsies, stem cell-based therapies, and diagnosis of infectious diseases due to bacteria and viruses are presented. Finally, the challenges in DEP research are discussed, and the reported solutions are explained. DEP's potential research directions are mentioned.
Healthcare service quality measurement in Malaysia: A scoping review

Chew KS, Wong SSL, Siew KL, Ab-Rahim R

Med J Malaysia, 2023 Jan;78(1):118-123.
PMID: 36715201

INTRODUCTION: Although healthcare service industry has been thriving in Malaysia, the types of healthcare service quality models used in past research as well as their key messages had not been explored. A scoping review was performed to determine the validated healthcare service quality models, the key messages of these past studies and potential research gaps that should be addressed in future studies.
MATERIALS AND METHODS: Relevant, peer-reviewed, Englishlanguage articles on healthcare service quality in Malaysia were independently searched by the authors using the SCOPUS and EMERALD databases. Articles that do not directly address healthcare service quality within the Malaysian setting were excluded. Additional articles were identified from the reference lists of the selected articles and from Google search engine. A total of 43 out of 2,749 articles were selected.
RESULTS: Most of these studies (28 out of the 43 articles, 65.1%) in this scoping review used either the original or a modified version of SERVQUAL instrument to measure healthcare service quality. Significant positive relationships between tangibles, assurance and empathy with patient satisfaction were identified. As SERVQUAL primarily measures the functional dimension of service quality, this suggests that past studies on Malaysian healthcare services emphasised heavily on the functional dimension of healthcare service quality. Functional dimension refers to the expressive performance on how the healthcare service is rendered whereas technical dimension refers to the types of services rendered as well as its safety and efficacy.
CONCLUSION: A pertinent research gap identified in this review is the lack of studies that measure both technical and functional dimensions comprehensively. Future research should adopt a more holistic (incorporating both technical dimension and functional dimension) measurement of healthcare service quality.
CD47 and CD36 expressions in the placenta of mothers with chorioamnionitis

Hanim BS, Rahim RA, Mohd Salleh MF, Zakaria H, Abd Shukor N

Malays J Pathol, 2023 Dec;45(3):463-471.
PMID: 38155387

INTRODUCTION: Chorioamnionitis is the inflammation of the placenta and is histologically defined as the presence of neutrophilic infiltration into the chorio-amnion membrane with and without involvement of the umbilical cord. Currently, the inflammatory mediators involved in the eliciting of inflammatory response is still largely under investigation. CD47 and CD36 are pro-inflammatory molecules that are still under investigation. The aim of this study was to determine the expressions of CD47 and CD36 in the placenta of mothers with chorioamnionitis.
MATERIALS AND METHODS: This was a cross-sectional study, involving a total of 100 cases that comprised of acute subchorionitis (stage I, n=20), acute chorioamnionitis (stage II, n=20), acute necrotising chorioamnionitis (stage III, n=20) and non-chorioamnionitis placenta as control (n=40). All tissue blocks were retrieved from the archived pathology record over a period of 4 years. CD36 and CD47 immunohistochemistry were performed on all cases and their expression in various cell types on the placenta were analysed.
RESULTS: CD36 was expressed only on the foetal vascular endothelial cells. Interestingly, CD47 showed positive staining on the neutrophils and its expression was significantly different between maternal inflammatory response stage II chorioamnionitis (n=13/20, p<0.001) with stage I and stage III chorioamnionitis.
DISCUSSION: Our study showed CD47 was expressed in the neutrophils and it was associated with poorer perinatal outcomes and it may have a role in the pathogenesis of chorioamnionitis.
Fulltext Engineering integrative vectors based on phage site-specific recombination mechanism for Lactococcus lactis

Koko I, Song AA, Masarudin MJ, Abdul Rahim R

BMC Biotechnol, 2019 11 27;19(1):82.
PMID: 31775775 DOI: 10.1186/s12896-019-0575-x

BACKGROUND: Site-specific integration system allows foreign DNA to be integrated into the specific site of the host genome, enabling stable expression of heterologous protein. In this study, integrative vectors for secretion and surface display of proteins were constructed based on a lactococcal phage TP901-1 integrating system.
RESULTS: The constructed integration system comprises of a lactococcal promoter (PnisA or P170), phage attachment site (attP) from bacteriophage TP901-1, a signal peptide (USP45 or SPK1) for translocation of the target protein, and a PrtP344 anchor domain in the case of the integrative vectors for surface display. There were eight successfully constructed integrative vectors with each having a different combination of promoter and signal peptide; pS1, pS2, pS3 and pS4 for secretion, and pSD1, pSD2, pSD3 and pSD4 for surface display of desired protein. The integration of the vectors into the host genome was assisted by a helper vector harbouring the integrase gene. A nuclease gene was used as a reporter and was successfully integrated into the L. lactis genome and Nuc was secreted or displayed as expected. The signal peptide SPK1 was observed to be superior to USP45-LEISSTCDA fusion in the secretion of Nuc. As for the surface display integrative vector, all systems developed were comparable with the exception of the combination of P170 promoter with USP45 signal peptide which gave very low signals in whole cell ELISA.
CONCLUSION: The engineered synthetic integrative vectors have the potential to be used for secretion or surface display of heterologous protein production in lactococcal expression system for research or industrial purposes, especially in live vaccine delivery.

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