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Fulltext Experimental validation of new self-voltage balanced 9L-ANPC inverter for photovoltaic applications

Sathik MJ, Almakhles DJ, Sandeep N, Siddique MD

Sci Rep, 2021 Mar 03;11(1):5067.
PMID: 33658562 DOI: 10.1038/s41598-021-84531-z

Multilevel inverters play an important role in extracting the power from renewable energy resources and delivering the output voltage with high quality to the load. This paper proposes a new single-stage switched capacitor nine-level inverter, which comprises an improved T-type inverter, auxiliary switch, and switched cell unit. The proposed topology effectively reduces the DC-link capacitor voltage and exhibits superior performance over recently switched-capacitor inverter topologies in terms of the number of power components and blocking voltage of the switches. A level-shifted multilevel pulse width modulation scheme with a modified triangular carrier wave is implemented to produce a high-quality stepped output voltage waveform with low switching frequency. The proposed nine-level inverter's effectiveness, driven by the recommended modulation technique, is experimentally verified under varying load conditions. The power loss and efficiency for the proposed nine-level inverter are thoroughly discussed with different loads.
Histopathology and cytopathology of white spot syndrome virus (WSSV) in cultured Penaeus monodon from peninsular Malaysia with emphasis on pathogenesis and the mechanism of white spot formation

Wang YG, Hassan MD, Shariff M, Zamri SM, Chen X

Dis Aquat Organ, 1999 Dec 22;39(1):1-11.
PMID: 11407399

Since 1994, white spot syndrome virus (WSSV) has been detected in cultured shrimp Penaeus monodon in Peninsular Malaysia. The gross signs, target organs and histo-cytopathology for the viral infection were studied and it was found to infect most organs and tissues including oocytes, but not hepatopancreatocytes and epithelial cells of the midgut, which were regarded as refractory tissues. Based on a time-sequence of ultrastructural cytopathology, 4 cytopathic profiles and 6 phases of viral morphogenesis were described. The virions were elliptical to short rods with trilamilar envelopes that measured 305 +/- 30 x 127 +/- 11 nm. Viral nucleosomes were often present singly in infected nuclei and were associated with the early stages of viral replication. The structure of WSSV pathognomonic white, cuticular lesions was examined at the microscopic and ultrastructural levels and the mechanism of their formation appeared to be related to the disruption of exudate transfer from epithelial cells to the cuticle via cuticular pore canals.
A new bacterial white spot syndrome (BWSS) in cultured tiger shrimp Penaeus monodon and its comparison with white spot syndrome (WSS) caused by virus

Wang YG, Lee KL, Najiah M, Shariff M, Hassan MD

Dis Aquat Organ, 2000 May 25;41(1):9-18.
PMID: 10907134

This paper describes a new bacterial white spot syndrome (BWSS) in cultured tiger shrimp Penaeus monodon. The affected shrimp showed white spots similar to those caused by white spot syndrome virus (WSSV), but the shrimp remained active and grew normally without significant mortalities. The study revealed no evidence of WSSV infection using electron microscopy, histopathology and nested polymerase chain reaction. Electron microscopy indicated bacteria associated with white spot formation, and with degeneration and discoloration of the cuticle as a result of erosion of the epicuticle and underlying cuticular layers. Grossly the white spots in BWSS and WSS look similar but showed different profiles under wet mount microscopy. The bacterial white spots were lichen-like, having perforated centers unlike the melanized dots in WSSV-induced white spots. Bacteriological examination showed that the dominant isolate in the lesions was Bacillus subtilis. The occurrence of BWSS may be associated with the regular use of probiotics containing B. subtilis in shrimp ponds. The externally induced white spot lesions were localized at the integumental tissues, i.e., cuticle and epidermis, and connective tissues. Damage to the deeper tissues was limited. The BWS lesions are non-fatal in the absence of other complications and are usually shed through molting.
Fulltext Evaluation of the Effects of Cement and Lime with Rice Husk Ash as an Additive on Strength Behavior of Coastal Soil

Eliaslankaran Z, Daud NNN, Yusoff ZM, Rostami V

Materials (Basel), 2021 Feb 28;14(5).
PMID: 33670914 DOI: 10.3390/ma14051140

Coastal accretion and erosion are unavoidable processes as some coastal sediments undergo modification and stabilization. This study was conducted to investigate the geotechnical behavior of soil collected from Bagan Lalang coast and treated with lime, cement, and rice husk ash (RHA) to design a low-cost alternative mixture with environmentally friendly characteristics. Laboratory tests were carried out to analyze the physical properties of the soil (Atterberg limits and compaction properties), together with mechanical characteristics (direct shear and unconfined compressive strength (UCS) tests) to determine the effect of different ratios of stabilizer/pozzolan on the coastal soil and the optimum conditions for each mixture. Part of the purpose of this study was also to analyze the shear behavior of the coastal soil and monitor the maximum axial compressive stress that the treated specimens can bear under zero confining pressure. Compared to the natural soil, the soil treated with lime and rice husk ash (LRHA) in the ratio of 1:2 (8% lime content) showed a tremendous increase in shear stress under the normal stress of 200 kPa. The strength parameters such as the cohesion (c) and internal friction angle (ϕ) values showed a significant increase. Cohesion values increased considerably in samples cured for 90 days compared to specimens cured for 7 days with additional LRHA in the ratio of 1:2 (28%).
Fulltext Predictors of Self-Reported Hand Hygiene Performance among Nurses at Tertiary Care Hospitals in East Coast Malaysia

Rahim MHA, Ibrahim MI, Noor SSM, Fadzil NM

Int J Environ Res Public Health, 2021 01 07;18(2).
PMID: 33430195 DOI: 10.3390/ijerph18020409

BACKGROUND: Hand hygiene (HH) is the simplest and most effective way to reduce the incidence of healthcare-associated infections (HCAIs).
METHODS: This cross-sectional study aimed to determine factors associated with self-reported HH performance among nurses at Kelantan tertiary care hospitals. A sample of 438 registered nurses was selected through a stratified random sampling method. Self-reported HH performance was assessed using a validated WHO self-administered HH knowledge and perception questionnaire for healthcare workers.
RESULTS: A multiple linear regression analysis was performed to identify the predictors. The factors that significantly predicted self-reported HH performance among nurses included perception score (beta coefficient (β) = 0.260; 95% CI: 0.200, 0.417; p < 0.001), pediatric department (β = -0.104; 95% CI: -9.335, -2.467; p < 0.001), and orthopedic department (β = -5.957; 95% CI: -9.539, -0.720; p < 0.023), adjusted R2 = 0.102; p < 0.001. Nurses with a strong perception and belief in HH were more likely to have better HH performance. Compared to pediatric and orthopedic, surgical departments were associated with better self-reported HH performance.
CONCLUSIONS: This study showed the importance of factors that could improve the intervention's performance in HH strategy. Lack of perception and HH program intervention in departments engaged in patient care could lead to poor HH practices, thus increasing HCAIs and antimicrobial resistance (AMR).
Production of bioethanol by direct bioconversion of oil-palm industrial effluent in a stirred-tank bioreactor

Alam MZ, Kabbashi NA, Hussin SN

J Ind Microbiol Biotechnol, 2009 Jun;36(6):801-8.
PMID: 19294441 DOI: 10.1007/s10295-009-0554-7

The purpose of this study was to evaluate the feasibility of producing bioethanol from palm-oil mill effluent generated by the oil-palm industries through direct bioconversion process. The bioethanol production was carried out through the treatment of compatible mixed cultures such as Thrichoderma harzianum, Phanerochaete chrysosporium, Mucor hiemalis, and yeast, Saccharomyces cerevisiae. Simultaneous inoculation of T. harzianum and S. cerevisiae was found to be the mixed culture that yielded the highest ethanol production (4% v/v or 31.6 g/l). Statistical optimization was carried out to determine the operating conditions of the stirred-tank bioreactor for maximum bioethanol production by a two-level fractional factorial design with a single central point. The factors involved were oxygen saturation level (pO(2)%), temperature, and pH. A polynomial regression model was developed using the experimental data including the linear, quadratic, and interaction effects. Statistical analysis showed that the maximum ethanol production of 4.6% (v/v) or 36.3 g/l was achieved at a temperature of 32 degrees C, pH of 6, and pO(2) of 30%. The results of the model validation test under the developed optimum process conditions indicated that the maximum production was increased from 4.6% (v/v) to 6.5% (v/v) or 51.3 g/l with 89.1% chemical-oxygen-demand removal.
Optimization of lignin peroxidase production and stability by Phanerochaete chrysosporium using sewage-treatment-plant sludge as substrate in a stirred-tank bioreactor

Alam MZ, Mansor MF, Jalal KC

J Ind Microbiol Biotechnol, 2009 May;36(5):757-64.
PMID: 19259713 DOI: 10.1007/s10295-009-0548-5

A laboratory-scale study was carried out to produce lignin peroxidase (ligninase) by white rot fungus (Phanerochaete chrysosporium) using sewage-treatment-plant (STP) sludge as the major substrate. The optimization was done using full-factorial design (FFD) with agitation and aeration as the two parameters. Nine experiments indicated by the FFD were fermented in a stirred-tank bioreactor for 3 days. A second-order quadratic model was developed using the regression analysis of the experimental results with the linear, quadratic, and interaction effects of the parameters. Analysis of variance (ANOVA) showed a high coefficient of determination (R (2)) value of 0.972, thus indicating a satisfactory fit of the quadratic model with the experimental data. Using statistical analysis, the optimum aeration and agitation rates were determined to be 2.0 vvm and 200 rpm, respectively, with a maximum activity of 225 U l(-1) in the first 3 days of fermentation. The validation experiment showed the maximum activity of lignin peroxidase was 744 U l(-1) after 5 days of fermentation. The results for the tests of the stability of lignin peroxidase showed that the activity was more than 80% of the maximum for the first 12 h of incubation at an optimum pH of 5 and temperature of 55 degrees C.
Nanodiagnostic Attainments and Clinical Perspectives on C-Reactive Protein: Cardiovascular Disease Risks Assessment

Letchumanan I, Arshad MKM, Gopinath SCB

Curr Med Chem, 2021;28(5):986-1002.
PMID: 31971105 DOI: 10.2174/0929867327666200123092648

Cardiovascular disease (CVD) has become one of the leading causes of morbidity and mortality in both men and women. According to the World Health Organization (WHO), ischemic heart disease is the major issue due to the narrowing of the coronary artery by plaque formation on the artery wall, which causes an inadequate flow of oxygen and blood to the heart and is called 'coronary artery disease'. The CVD death rate increased by up to 15% in 2016 (~17.6 million) compared to the past decade. This tremendous increment urges the development of a suitable biomarker for rapid and early diagnosis. Currently, C-reactive protein (CRP) is considered an outstanding biomarker for quick and accurate outcomes in clinical analyses. Various techniques have also been used to diagnose CVD, including surface plasmon resonance (SPR), colorimetric assay, enzyme-linked immunosorbent assay (ELISA), fluoro-immunoassays, chemiluminescent assays, and electrical measurements. This review discusses such diagnostic strategies and how current, cutting-edge technologies have enabled the development of high-performance detection methodologies. Concluding remarks have been made concerning the clinical significance and the use of nanomaterial in medical diagnostics towards nanotheranostics.
Fulltext Alpha1B-adrenoceptors mediate adrenergically-induced renal vasoconstrictions in rats with renal impairment

Khan MA, Sattar MA, Abdullah NA, Johns EJ

Acta Pharmacol Sin, 2008 Feb;29(2):193-203.
PMID: 18215348 DOI: 10.1111/j.1745-7254.2008.00727.x

This study examined whether alpha1B-adrenoceptors are involved in mediating adrenergically-induced renal vasoconstrictor responses in rats with pathophysiological and normal physiological states.
Fulltext Enhancement of Live Food Nutritional Status with Essential Nutrients for Improving Aquatic Animal Health: A Review

Samat NA, Yusoff FM, Rasdi NW, Karim M

Animals (Basel), 2020 Dec 21;10(12).
PMID: 33371528 DOI: 10.3390/ani10122457

At the present time, no artificial larval diet is capable of entirely fulfilling the dietary requirements of several larval fish and crustacean species. Zooplankton live food is the basic foundation of fish larviculture, and successful rearing of fish larvae still heavily depends on an adequate supply of nutritious live food. Despite being important, the production protocols of copepods and cladocerans (Moina) are still underdeveloped in hatcheries. Rotifers and Artemia are the most commonly used live foods. However, these live foods are evidently lacking in crucial nutrient constituents. Hence, through nutrient enrichment, live food with the nutritional profile that meets the requirements of fish larvae can be produced. With the aim to maximize the effectiveness of production to optimize profitability, it is important to evaluate and improve culture techniques for the delivery of micro- and macro-nutrients as feed supplements to larvae in aquaculture systems. Bioencapsulation and enrichment are the evolving techniques in aquaculture that are commonly employed to enhance the nutritional quality of live food by integrating nutrients into them, which subsequently improves the growth, survival, and disease resistance of the consuming hosts. This review aims to highlight some of the approaches and methods used to improve the nutritional quality of live food by modifying their nutrient composition, which could have immense promise in the enhancement of aquatic animal health.
Fulltext Insulin-Loaded Barium Salt Particles Facilitate Oral Delivery of Insulin in Diabetic Rats

Zaman R, Karim ME, Othman I, Zaini A, Chowdhury EH

Pharmaceutics, 2020 Jul 29;12(8).
PMID: 32751231 DOI: 10.3390/pharmaceutics12080710

Oral delivery is considered as the most preferred and yet most challenging mode of drug administration; especially a fragile and sensitive peptide like insulin that shows extremely low bioavailability through the gastro-intestinal (GIT) route. To address this problem, we have designed a novel drug delivery system (DDS) using precipitation-induced Barium (Ba) salt particles. The DDS can load insulin molecules and transport them through the GIT route. There were several in vitro simulation tests carried out to prove the efficiency of Ba salt particles as oral delivery candidates. All three Ba salt particles (BaSO4, BaSO3, and BaCO3) showed very good loading of insulin (>70% in all formulations) and a degree of resistance throughout a wide range of pHs from basic to acidic conditions when assessed by spectrophotometry. Particles and insulin-associated particles were morphologically assessed and characterized using FE-SEM and FT-IR. A set of tests were designed and carried out with mucin to predict whether the particles are potentially capable of overcoming one of the barriers for crossing intestinal epithelium. The mucin binding experiment demonstrated 60-100% of mucin adhesion to the three different particles. FT-IR identifies the characteristic peaks for mucin protein, particles, and particle-mucin complex re-confirming mucin adhesion to the particles. Finally, the effectiveness of nano-insulin was tested on streptozotocin (STZ) induced diabetic rats. A short acting human insulin analog, insulin aspart, was loaded into Ba salt particles at a dose of 100 IU/Kg prior to oral administration. Among the three formulations, insulin aspart-loaded BaSO4 and BaCO3 particles dramatically reduced the existing hyperglycemia. BaSO4 with loaded Insulin showed an onset of glucose-lowering action within 1 hr, with blood glucose level measured significantly lower compared to the 2nd and 3rd h (p < 0.05). Insulin-loaded BaCO3 particles showed a significant decrease in blood glucose level at 1-2 h, although the glucose level started to show a slight rise at 3rd h and by 4th h, it was back to baseline level. However, although BaSO3 particles with loaded insulin showed a trend of reduction in blood glucose level, the reduction was not found to be significant (p < 0.05) at any point in time. Therefore, oral formulations of insulin/BaSO4 and insulin/BaCO3 particles were observed as effective as native insulin aspart subcutaneous formulation in terms of onset and duration of action. Further investigation will be needed to reveal bioavailability and mechanism of action of this novel Nano-Insulin formulations.
Fulltext Correction to: Effectiveness of mobile SMS based counselling intervention in improving knowledge, attitude and practices of HIV/AIDS patients enrolled in hospitals/NGOs in Terengganu, Malaysia: a mixed mode study protocol

Hossain MM, Min RM, Muhammad Z, Mani KKC

BMC Public Health, 2020 Aug 24;20(1):1278.
PMID: 32838769 DOI: 10.1186/s12889-020-09395-w

An amendment to this paper has been published and can be accessed via the original article.
Fulltext Effectiveness of a Novel Index System in Preventing Early Hearing Loss among Furniture Industry Skills Training Students in Malaysia

Abdul Rahim KA, Jewaratnam J, Che Hassan CR, Hamid MD

Int J Environ Res Public Health, 2020 10 31;17(21).
PMID: 33142732 DOI: 10.3390/ijerph17218032

Occupational noise-induced hearing loss (ONIHL) is the most reported occupational disease in Malaysia. ONIHL is aggravated by the presence of early hearing loss amongst the youth prior to entering a real working environment. At technical and vocational education training (TVET) institutions, students may develop early ONIHL because training workshops are designed imitating the industrial working environment to produce skilled workers. The exceeding noise level at workshops and recent risk of non-occupational noise can cause early ONIHL among these students. Therefore, ONIHL must be addressed at the early stage of producing skilled workers. Octa hearing conservation index (OHCI) system is developed as a management and monitoring tool for hearing conservation program (HCP) in TVET institutions. Six existing and two new HCP components were used to build the index system. A pilot test on the effectiveness of the OHCI system was conducted in a selected TVET institution for six months. The post-HCP shows a 52.6% improvement compared to the pre-HCP. The implementation of HCP has shown improved awareness on the hazards of loud noise exposure and active use of hearing protection devices among participants. The OHCI system has a great potential as a tool to improve HCP implementation in TVET institutions, and eventually, industry.
Fulltext Correlated transitions in TKE and mass distributions of fission fragments described by 4-D Langevin equation

Usang MD, Ivanyuk FA, Ishizuka C, Chiba S

Sci Rep, 2019 Feb 06;9(1):1525.
PMID: 30728435 DOI: 10.1038/s41598-018-37993-7

We have decomposed to symmetric and asymmetric modes the mass-TKE fission fragment distributions calculated by 4-dimensional Langevin approach and observed how the dominant fission mode and symmetric mode change as functions of [Formula: see text] of the fissioning system in the actinides and trans-actinide region. As a result, we found that the symmetric mode makes a sudden transition from super-long to super short fission mode around 254Es. The dominant fission modes on the other hand, are persistently asymmetric except for 258Fm, 259Fm and 260Md when the dominant fission mode suddenly becomes symmetric although it returns to the asymmetric mode around 256No. These correlated "twin transitions" have been known empirically by Darleane Hoffman and her group back in 1989, but for the first time we have given a clear explanation in terms of a dynamical model of nuclear fission. More specifically, since we kept the shape model parameters unchanged over the entire mass region, we conclude that the correlated twin transition emerge naturally from the dynamics in 4-D potential energy surface.
Occurrence and level of emerging organic contaminant in fish and mollusk from Klang River estuary, Malaysia and assessment on human health risk

Omar TFT, Aris AZ, Yusoff FM, Mustafa S

Environ Pollut, 2019 May;248:763-773.
PMID: 30851586 DOI: 10.1016/j.envpol.2019.02.060

The occurrence, level, and distribution of multiclass emerging organic contaminants (EOCs) in fish and mollusks from the Klang River estuary were examined. The targeted EOCs for this assessment were phenolic endocrine disrupting compounds (bisphenol A, 4-OP, and 4-NP), organophosphorous pesticides (quinalphos, chlorpyrifos, and diazinon), estrogenic hormones (E2, E1, and EE2), and pharmaceutically active chemicals (primidone, sulfamethoxazole, dexamethasone, diclofenac, amoxicillin, progesterone, and testosterone). Results from this study showed that the prevalent contamination of the Klang River estuary by EOCs with diclofenac, bisphenol A, progesterone, and amoxicillin were predominantly detected in fish and mollusks. Among the EOCs, diclofenac and progesterone had the highest concentrations in fish and mollusk samples, respectively. The concentrations of diclofenac and progesterone in fish and mollusk samples range from 1.42 ng/g to 10.76 ng/g and from 0.73 ng/g to 9.57 ng/g, respectively. Bisphenol A should also be highlighted because of its significant presence in both fish and mollusks. The concentration of bisphenol A in both matrices range from 0.92 ng/g to 5.79 ng/g. The calculated hazard quotient (HQ) for diclofenac, bisphenol A, and progesterone without consideration to their degradation byproduct were less than one, thus suggesting that the consumption of fish and mollusks from the Klang River estuary will unlikely pose any health risk to consumers on the basis of the current assessment. Nonetheless, this preliminary result is an important finding for pollution studies in Malaysian tropical coastal ecosystems, particularly for organic micropollutant EOCs, and can serve as a baseline database for future reference.
Occurrence and risk assessment of multiclass endocrine disrupting compounds in an urban tropical river and a proposed risk management and monitoring framework

Wee SY, Aris AZ, Yusoff FM, Praveena SM

Sci Total Environ, 2019 Jun 25;671:431-442.
PMID: 30933799 DOI: 10.1016/j.scitotenv.2019.03.243

Endocrine disrupting compounds (EDCs) are an emerging environmental concern and commonly occur as a mixture of compounds. The EDC mixture can be more toxic than any single compound. The present study analyses EDCs in surface water in the case of an urban tropical river, the Langat River, using the multiresidue analytical method of solid phase extraction and liquid chromatography-tandem mass spectrometry (SPE-LC-MS/MS). The Langat River is used as a drinking water source and is treated for Malaysian drinking water supply. A total of 14 EDCs i.e. five hormones, seven pharmaceuticals, one pesticide, and one plasticizer were detected. Caffeine was observed to be highest at 19.33 ng/L, followed by bisphenol A and diclofenac at 8.24 ng/L and 6.15 ng/L, respectively. Using a conservative risk quotient (RQ) method, EDCs were estimated for having negligible risks under acute and chronic exposure (RQ 
Fulltext Electrospun Combination of Peppermint Oil and Copper Sulphate with Conducive Physico-Chemical properties for Wound Dressing Applications

Jaganathan SK, Mani MP, Khudzari AZM

Polymers (Basel), 2019 Apr 01;11(4).
PMID: 30960571 DOI: 10.3390/polym11040586

The ultimate goal in tissue engineering is to fabricate a scaffold which could mimic the native tissue structure. In this work, the physicochemical and biocompatibility properties of electrospun composites based on polyurethane (PU) with added pepper mint (PM) oil and copper sulphate (CuSO₄) were investigated. Field Emission Electron microscope (FESEM) study depicted the increase in mean fiber diameter for PU/PM and decrease in fiber diameter for PU/PM/CuSO₄ compared to the pristine PU. Fourier transform infrared spectroscopy (FTIR) analysis revealed the formation of a hydrogen bond for the fabricated composites as identified by an alteration in PU peak intensity. Contact angle analysis presented the hydrophobic nature of pristine PU and PU/PM while the PU/PM/CuSO₄ showed hydrophilic behavior. Atomic force microscopy (AFM) analysis revealed the increase in the surface roughness for the PU/PM while PU/PM/CuSO₄ showed a decrease in surface roughness compared to the pristine PU. Blood compatibility studies showed improved blood clotting time and less toxic behavior for the developed composites than the pristine PU. Finally, the cell viability of the fabricated composite was higher than the pristine PU as indicated in the MTS assay. Hence, the fabricated wound dressing composite based on PU with added PM and CuSO₄ rendered a better physicochemical and biocompatible nature, making it suitable for wound healing applications.
Fulltext Supplementation of 100% Flesh Watermelon [Citrullus lanatus (Thunb.) Matsum. and Nakai] Juice Improves Swimming Performance in Rats

Ridwan R, Razak HRA, Adenan MI, Saad WMM

Prev Nutr Food Sci, 2019 Mar;24(1):41-48.
PMID: 31008095 DOI: 10.3746/pnf.2019.24.1.41

Nutritional intervention of fruit juice supplementation is able to maximize exercise performance. Watermelon [Citrullus lanatus (Thunb.) Matsum. and Nakai] contains high L-citrulline content and consumption of watermelon juice may promote ergogenic effects. The aim of the present study was to investigate the role of 100% flesh watermelon juice and 100% rind watermelon juice supplementation for 14 days on swimming performance in rats. Twenty four male Sprague-Dawley rats were randomly divided into four groups: Cx group of rats supplemented with filtered tap water (negative control), L-cit group of rats supplemented with L-citrulline (positive control), FR group of rats supplemented with 100% flesh watermelon juice, and RR group of rats supplemented with 100% rind watermelon juice. Each group was supplemented for 14 days ad libitum prior to swimming exercise protocol. The rats were performed swimming exercise for 3 days and swimming time until exhaustion was measured. Plasma samples were collected to measure lactate concentration, ammonia concentration, and nitric oxide production. Rats supplemented with 100% flesh watermelon juice demonstrated significantly prolonged of swimming time until exhaustion, reduction of lactate and ammonia concentrations, and increased of nitric oxide production compared to Cx and L-cit groups (P<0.05). These findings postulate that supplementation with 100% flesh watermelon juice improves endurance in swimming performance.
Fulltext Bioactive Compounds of Pseudoalteromonas sp. IBRL PD4.8 Inhibit Growth of Fouling Bacteria and Attenuate Biofilms of Vibrio alginolyticus FB3

Supardy NA, Ibrahim D, Mat Nor SR, Noordin WNM

Pol J Microbiol, 2019;68(1):21-33.
PMID: 31050250 DOI: 10.21307/pjm-2019-003

Biofouling is a phenomenon that describes the fouling organisms attached to man-made surfaces immersed in water over a period of time. It has emerged as a chronic problem to the oceanic industries, especially the shipping and aquaculture fields. The metal-containing coatings that have been used for many years to prevent and destroy biofouling are damaging to the ocean and many organisms. Therefore, this calls for the critical need of natural product-based antifoulants as a substitute for its toxic counterparts. In this study, the antibacterial and antibiofilm activities of the bioactive compounds of Pseudoalteromonas sp. IBRL PD4.8 have been investigated against selected fouling bacteria. The crude extract has shown strong antibacterial activity against five fouling bacteria, with inhibition zones ranging from 9.8 to 13.7 mm and minimal inhibitory concentrations of 0.13 to 8.0 mg/ml. Meanwhile, the antibiofilm study has indicated that the extract has attenuated the initial and pre-formed biofilms of Vibrio alginolyticus FB3 by 45.37 ± 4.88% and 29.85 ± 2.56%, respectively. Moreover, micrographs from light and scanning electron microscope have revealed extensive structural damages on the treated biofilms. The active fraction was fractionated with chromatographic methods and liquid chromatography-mass spectroscopy analyses has further disclosed the presence of a polyunsaturated fatty acid 4,7,10,13-hexadecatetraenoic acid (C16H24O2). Therefore, this compound was suggested as a potential bioactive compound contributing to the antibacterial property. In conclusion, Pseudoalteromonas sp. IBRL PD4.8 is a promising source as a natural antifouling agent that can suppress the growth of five fouling bacteria and biofilms of V. alginolyticus FB3.
Biofouling is a phenomenon that describes the fouling organisms attached to man-made surfaces immersed in water over a period of time. It has emerged as a chronic problem to the oceanic industries, especially the shipping and aquaculture fields. The metal-containing coatings that have been used for many years to prevent and destroy biofouling are damaging to the ocean and many organisms. Therefore, this calls for the critical need of natural product-based antifoulants as a substitute for its toxic counterparts. In this study, the antibacterial and antibiofilm activities of the bioactive compounds of Pseudoalteromonas sp. IBRL PD4.8 have been investigated against selected fouling bacteria. The crude extract has shown strong antibacterial activity against five fouling bacteria, with inhibition zones ranging from 9.8 to 13.7 mm and minimal inhibitory concentrations of 0.13 to 8.0 mg/ml. Meanwhile, the antibiofilm study has indicated that the extract has attenuated the initial and pre-formed biofilms of Vibrio alginolyticus FB3 by 45.37 ± 4.88% and 29.85 ± 2.56%, respectively. Moreover, micrographs from light and scanning electron microscope have revealed extensive structural damages on the treated biofilms. The active fraction was fractionated with chromatographic methods and liquid chromatography-mass spectroscopy analyses has further disclosed the presence of a polyunsaturated fatty acid 4,7,10,13-hexadecatetraenoic acid (C16H24O2). Therefore, this compound was suggested as a potential bioactive compound contributing to the antibacterial property. In conclusion, Pseudoalteromonas sp. IBRL PD4.8 is a promising source as a natural antifouling agent that can suppress the growth of five fouling bacteria and biofilms of V. alginolyticus FB3.
Extracellular calcium modulates insulin's action on enzymes controlling cyclic AMP metabolism in intact hepatocytes

Irvine F, Wallace AV, Sarawak SR, Houslay MD

Biochem. J., 1993 Jul 01;293 ( Pt 1):249-53.
PMID: 8392336

Absence of physiological concentrations of extracellular Ca2+ in the Krebs-Henseleit incubation buffer did not affect the ability of 10 nM glucagon (< 5%) to increase hepatocyte intracellular cyclic AMP concentrations, but severely ablated (by approximately 70%) the ability of 10 nM insulin to decrease these elevated concentrations. Cyclic AMP metabolism is determined by production by adenylate cyclase and degradation by cyclic AMP phosphodiesterase (PDE). In the absence of added extracellular Ca2+ (2.5 mM), insulin's ability to activate PDE activity was selectively compromised, showing a failure of insulin to activate two of the three insulin-stimulated activities, namely the 'dense-vesicle' and peripheral plasma-membrane (PPM) PDEs. In the absence of added Ca2+, insulin's ability to inhibit adenylate cyclase activity in intact hepatocytes was decreased dramatically. Vasopressin and adrenaline (+ propranolol) failed to elicit the activation of either the 'dense-vesicle' or the PPM-PDEs. The presence of physiological concentrations of extracellular Ca2+ in the incubation medium is shown to be important for the appropriate generation of insulin's actions on cyclic AMP metabolism.

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