Displaying publications 181 - 200 of 398 in total

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  1. Abdul Rahman M, Mohamad Haron DE, Hollows RJ, Abdul Ghani ZDF, Ali Mohd M, Chai WL, et al.
    PeerJ, 2020;8:e9304.
    PMID: 32547888 DOI: 10.7717/peerj.9304
    Head and neck squamous cell carcinoma (HNSCC) represents a significant world health problem, with approximately 600,000 new cases being diagnosed annually. The prognosis for patients with HNSCC is poor and, therefore, the identification of biomarkers for screening, diagnosis and prognostication would be clinically beneficial. A limited number of studies have used lipidomics to profile lipid species in the plasma of cancer patients. However, the profile and levels of lysophosphatidic acid (LPA) species have not been examined in HNSCC. In this study, a targeted lipidomics approach using liquid chromatography triple quadrupole mass spectrometry (LCMS/MS) was used to analyse the concentration of LPA (16:0 LPA, 18:0 LPA, 18:1 LPA, 18:2 LPA and 20:4 LPA) in the plasma of patients with oral squamous cell carcinoma (OSCC) and nasopharyngeal carcinoma (NPC), together with healthy controls. The levels of three LPA species (18:1 LPA, 18:2 LPA and 20:4 LPA) were significantly lower in the plasma of OSCC patients, whilst the concentrations of all five LPA species tested were significantly lower in plasma from NPC patients. Furthermore, the order of abundance of LPA species in plasma was different between the control and cancer groups, with 16:0 LPA, 18:0 LPA levels being more abundant in OSCC and NPC patients. Medium to strong correlations were observed using all pairs of LPA species and a clear separation of the normal and tumour groups was observed using PCA analysis. In summary, the results of this study showed that the levels of several LPA species in the plasma of patients with OSCC and NPC were lower than those from healthy individuals. Understanding these variations may provide novel insights into the role of LPA in these cancers.
  2. Mustafa MG, Rajaee AH, Hamli H, A Rahim KA
    PeerJ, 2021;9:e12183.
    PMID: 34721960 DOI: 10.7717/peerj.12183
    The length-weight relationships (LWRs), condition factor (Kn), growth, mortality and exploitation status of three polynemid fishes, i.e., Filimanus xanthonema (Valenciennes, 1831), Polynemus melanochir (Valenciennes, 1831) and Polynemus paradiseus (Linnaeus, 1758) from Batang Lassa River estuary were estimated. Fish samples were caught during April 2019 to September 2020 using the ESBN (locally called Gnian) having 1.25 to 4.00 cm mesh size. The total length (TL) and body weight of each individual fish was measured to the nearest 0.1 cm and 0.01 g respectively. The growth coefficients (b) for F. xanthonema, P. melanochir and P. paradiseus, were 2.880, 2.717 and 2.724 with the R 2 values 0.956, 0.972 and 0.936 respectively. Estimated growth coefficients indicated a negative allometric growth pattern for all three threadfin fishes. To date, information regarding length-weight relationships for F. xanthonema and P. melanochir is insufficient whereas the information is available for P. paradiseus. About 40-48% of fishes exhibited flat or thin body shape (Kn < 1), 48-50% were rounded or fat (Kn > 1) and only 1-3% of fishes showed proportional body shape (Kn = 1). The growth parameters L∞ , K and ϕ' were estimated at 15.75 cm, 0.95 yr-1 and 2.37 for F. xanthonema; 27.61 cm 0.87 yr-1 and 2.82 for P. melanochir; and 27.30 cm, 0.58 yr-1 and 2.64 for P. paradiseus; respectively. The estimated natural mortality (M) included 2.10, 1.69 and 1.30 yr-1; the fishing mortality (F) 0.57, 0.67 and 0.60 yr-1; and exploitation ratio (E) 0.21, 0.28 and 0.31 for F. xanthonema, P. melanochir and P. paradiseus respectively. The study concluded that the stocks are still under exploitation (E < 0.5) condition. However, the studied Batang Lassa estuary could be a potential nursery ground considering the minimum lengths of 5.0, 3.8 and 4.0 cm for F. xanthonema, P. melanochir and P. paradiseus respectively. Therefore, management initiatives are needed to escape juvenile catches.
  3. Yeoh Y, Low TY, Abu N, Lee PY
    PeerJ, 2021;9:e12338.
    PMID: 34733591 DOI: 10.7717/peerj.12338
    Resistance to anti-cancer treatments is a critical and widespread health issue that has brought serious impacts on lives, the economy and public policies. Mounting research has suggested that a selected spectrum of patients with advanced colorectal cancer (CRC) tend to respond poorly to both chemotherapeutic and targeted therapeutic regimens. Drug resistance in tumours can occur in an intrinsic or acquired manner, rendering cancer cells insensitive to the treatment of anti-cancer therapies. Multiple factors have been associated with drug resistance. The most well-established factors are the emergence of cancer stem cell-like properties and overexpression of ABC transporters that mediate drug efflux. Besides, there is emerging evidence that signalling pathways that modulate cell survival and drug metabolism play major roles in the maintenance of multidrug resistance in CRC. This article reviews drug resistance in CRC as a result of alterations in the MAPK, PI3K/PKB, Wnt/β-catenin and Notch pathways.
  4. Muhammad Nawawi KN, Mokhtar NM, Wong Z, Mohd Azman ZA, Hsin Chew DC, Rehir R, et al.
    PeerJ, 2021;9:e12425.
    PMID: 34820182 DOI: 10.7717/peerj.12425
    Background: The incidence rate of colorectal cancer (CRC) in Asian countries is increasing. Furthermore, recent studies have shown a concerning rise in the incidence of CRC among younger patients aged less than 50 years. This study aimed to analyze the incidence trends and clinicopathological features in patients with early-onset CRC (EOCRC) and later-onset CRC (at age ≥ 50 years).

    Methods: A retrospective analysis was performed on 946 patients with CRC diagnosed from 1997 to 2017 at Universiti Kebangsaan Malaysia Medical Centre. The time trend was assessed by dividing the two decades into four 5-year periods. The mean age-standardized and age-specific incidence rates were calculated by using the 5-year cumulative population of Kuala Lumpur and World Health Organization standard population. The mean incidence was expressed per 100,000 person-years.

    Results: After a stable (all age groups) CRC incidence rate during the first decade (3.00 per 100,000 and 3.85 per 100,000), it sharply increased to 6.12 per 100,000 in the 2008-2012 period before decreasing to 4.54 per 100,000 in the 2013-2017 period. The CRC incidence trend in later-onset CRC showed a decrease in the 2013-2017 period. Contrariwise, for age groups of 40-44 and 45-49 years, the trends showed an increase in the latter 15 years of the study period (40-44 years: 1.44 to 1.92 to 2.3 per 100,000; 45-49 years: 2.87 to 2.94 to 4.01 per 100,000). Malays' EOCRC incidence rate increased from 2008-2012 to 2013-2017 for both the age groups 40-44 years (1.46 to 2.89 per 100,000) and 45-49 years (2.73 to 6.51 per 100,000). Nearly one-fifth of EOCRC cases were diagnosed at an advanced stage (Dukes D: 19.9%), and the majority of them had rectal cancer (72.8%).

    Conclusion: The incidence of EOCRC increased over the period 1997-2017; the patients were predominantly Malays, diagnosed at a later stage, and with cancer commonly localized in the rectal region. All the relevant stakeholders need to work on the management and prevention of CRC in Malaysia.

  5. Malviya R, Fuloria S, Verma S, Subramaniyan V, Sathasivam KV, Kumarasamy V, et al.
    PeerJ, 2021;9:e12392.
    PMID: 34820175 DOI: 10.7717/peerj.12392
    The present review aims to describe the commercial utilities and future perspectives of nanomedicines. Nanomedicines are intended to increase precision medicine and decrease the adverse effects on the patient. Nanomedicines are produced, engineered, and industrialized at the cellular, chemical, and macromolecular levels. This study describes the various aspects of nanomedicine such as governing outlooks over high use of nanomedicine, regulatory advancements for nanomedicines, standards, and guidelines for nanomedicines as per Therapeutic Goods Administration (TGA). This review also focuses on the patents and clinical trials based on nanoformulation, along with nanomedicines utilization as drug therapy and their market value. The present study concludes that nanomedicines are of high importance in biomedical and pharmaceutical production and offer better therapeutic effects especially in the case of drugs that possess low aqueous solubility. The factual data presented in this study will assist the researchers and health care professionals in understanding the applications of nanomedicine for better diagnosis and effective treatment of a disease.
  6. Roshidi N, Mohd Hassan NH, Abdul Hadi A, Arifin N
    PeerJ, 2021;9:e12483.
    PMID: 34824920 DOI: 10.7717/peerj.12483
    Background: Giardiasis is a neglected parasitic zoonotic disease caused by Giardia duodenalis that is often overlooked despite the damage inflicted upon humans and domestic/wild animals. Lack of surveillance studies, low sensitivity of diagnostic tools, and resistance to giardiasis treatment add to the challenge in managing giardiasis, leaving a gap that continues to render giardiasis a silent threat to public health worldwide. This situation is not much different in Malaysia, where giardiasis remains a public health problem, especially in the indigenous communities. Realizing the existence of gaps in the literature and information on giardiasis in Malaysia, this review aims to revisit and update the situation of giardiasis in Malaysia based on articles published in 20 years from 2000 to 2020, providing estimates on the incidence of giardiasis in humans, animals, and the environment, which may inform efforts to prevent and control the impact of giardiasis in the country.

    Methodology: We searched PubMed, Science Direct, and Scopus using MeSH terms and text keywords "Giardia duodenalis OR Giardia intestinalis OR Giardia lamblia OR intestinal protozoa AND Malaysia". Information was collected from all giardiasis reports published between 2000 and 2020.

    Results: Giardiasis in Malaysia is more prevalent among the poorest segments of the population, namely the indigenous communities and people living in densely populated areas such as slums and prisons, due to low standard of personal hygiene, unsafe water resources, and improper sanitation. While the prevalence data is hugely dependent on microscopic fecal examination in epidemiological studies of giardiasis, current studies mostly focused on species identification and genotype distribution by multilocus genotyping. Thus far, the outbreak of giardiasis has not been reported in the country, but the disease was found to be significantly associated with stunting, wasting, and malnutrition among children of the indigenous communities. Surveillance studies also discovered the simultaneous presence of Giardia in the animal-environments, including wild animals, ruminants, and treated and untreated water. The data collected here will be a useful addition to the literature body on giardiasis in Malaysia, which can be exploited in efforts to prevent and control the impact of giardiasis in the country.

    Conclusions: The last 10 years have shown that the overall mean rate of giardiasis in Malaysia is quite encouraging at 13.7%. While this figure appears to be declining, there has been a slight increase in the prevalence of underweight, stunting, and wasting among rural children in 2019. The fact that giardiasis is linked to long-term childhood developmental problems, indicates that addressing and providing better disease control against giardiasis should be a priority in supporting the national agenda to achieve Malaysia Global Nutrition Targets by 2025.

  7. Holzner A, Rayan DM, Moore J, Tan CKW, Clart L, Kulik L, et al.
    PeerJ, 2021;9:e12462.
    PMID: 34993012 DOI: 10.7717/peerj.12462
    Deforestation is a major threat to terrestrial tropical ecosystems, particularly in Southeast Asia where human activities have dramatic consequences for the survival of many species. However, responses of species to anthropogenic impact are highly variable. In order to establish effective conservation strategies, it is critical to determine a species' ability to persist in degraded habitats. Here, we used camera trapping data to provide the first insights into the temporal and spatial distribution of southern pig-tailed macaques (Macaca nemestrina, listed as 'Vulnerable' by the IUCN) across intact and degraded forest habitats in Peninsular Malaysia, with a particular focus on the effects of clear-cutting and selective logging on macaque occupancy. Specifically, we found a 10% decline in macaque site occupancy in the highly degraded Pasoh Forest Reserve from 2013 to 2017. This may be strongly linked to the macaques' sensitivity to intensive disturbance through clear-cutting, which significantly increased the probability that M. nemestrina became locally extinct at a previously occupied site. However, we found no clear relationship between moderate disturbance, i.e., selective logging, and the macaques' local extinction probability or site occupancy in the Pasoh Forest Reserve and Belum-Temengor Forest Complex. Further, an identical age and sex structure of macaques in selectively logged and completely undisturbed habitat types within the Belum-Temengor Forest Complex indicated that the macaques did not show increased mortality or declining birth rates when exposed to selective logging. Overall, this suggests that low to moderately disturbed forests may still constitute valuable habitats that support viable populations of M. nemestrina, and thus need to be protected against further degradation. Our results emphasize the significance of population monitoring through camera trapping for understanding the ability of threatened species to cope with anthropogenic disturbance. This can inform species management plans and facilitate the development of effective conservation measures to protect biodiversity.
  8. Abdul Aziz NFH, Abbasiliasi S, Abu Zarin M, Ng HS, Lan C, Tan JS
    PeerJ, 2021;9:e11920.
    PMID: 34963820 DOI: 10.7717/peerj.11920
    Background: Current advances in biotechnology have been looked at as alternative approaches towards the limited product recovery due to time- and cost-consuming drawbacks on the conventional purification methods. This study aimed to purify bovine serum albumin (BSA) as an exemplary target product using an aqueous impregnated resin system (AIRS). This method implies the concept of hydrophobicity of polymer that impregnated into the resins and driven by electrostatic attractions and hydrophilicity of aqueous salt solution to extract the target product.

    Methods: The extraction behaviors of impregnation in terms of stability and adsorption kinetics via protein-aqueous polymer impregnated resin were studied. Impregnation stability was determined by the leaching factor of polyethylene glycol (PEG). The major factors such as PEG molecular weights and concentration, pH of aqueous salt solution, extraction methods (sonication and agitation) and types of adsorbent material and concentration of aqueous salt phase influencing on partitioning of biomolecule were also investigated.

    Results: For impregnation stability, the leaching factor for Amberlite XAD4 did not exceed 1%. The scanning electron microscopy (SEM) image analysis of Amberlite XAD4 attributes the structural changes with impregnation of resins. For adsorption kinetics, Freundlich adsorption isotherm with the highest R2 value (0.95) gives an indication of favorable adsorption process. Performance of AIRS impregnated with 40% (w/w) of PEG 2000 was found better than aqueous-two phase system (ATPS) by yielding the highest recovery of BSA (53.72%). The outcomes of this study propound the scope for the application of AIRS in purification of biomolecules.

  9. Zainal Baharin NH, Khairil Mokhtar NF, Mohd Desa MN, Gopalsamy B, Mohd Zaki NN, Yuswan MH, et al.
    PeerJ, 2021;9:e12193.
    PMID: 35003909 DOI: 10.7717/peerj.12193
    The emergence of antibiotic-resistant bacteria has become a significant and ever-increasing threat to global public health, increasing both morbidity and mortality rates, and the financial burden on health services. Infection by drug-resistant bacteria is anticipated to contribute to the demise of almost 10 million people by the year 2050 unless a competent and effective response is devised to engage with this issue. The emergence and spread of resistance are commonly caused by the excessive or inappropriate use of antibiotics and substandard pharmaceuticals. It arises when pathogens adapt to different conditions and develop self-defence mechanisms. Currently, novel antimicrobial peptides (AMPs) have been reported to be the sole cure for some clinical cases of infectious diseases such as sepsis and skin infections, although these agents may, on occasion, require administration together with an adjunctive low-dose antibiotic. Although AMPs are a promising alternative form of anti-microbial therapy and easily applied in the medical sector, they still have limitations that should not be taken lightly. Hence, this review explores the characteristics, advantages and disadvantages of AMPs for their potential in treating antibiotic-resistant pathogens.
  10. Fahim A, Himratul-Aznita WH, Abdul-Rahman PS, Alam MK
    PeerJ, 2022;9:e12251.
    PMID: 35036111 DOI: 10.7717/peerj.12251
    Background: Polymicrobial biofilms are notorious for causing intraoral tissue destruction. Streptococcus sanguinis and Streptococcus mitis, commensals of oral cavities, have been found co-existing with C. albicans in resistant oral infections. There is an urgent need to find alternative treatment options. This study aims to assess the efficacy of garlic (G) and bakuchiol (Bk) combination against candida virulent genes and their subsequently secreted proteins.

    Methods: In vitro single species biofilms of C. albicans, and mixed species biofilms formed in combination with streptococci were exposed to bakuchiol and garlic extract (Bk+G). Gene expression of agglutinin-like sequence (ALS1), (ALS3), adhesin-like wall proteins (HWP1) and aspartyl proteinases (SAP5) were determined using qPCR and their subsequent proteins were assessed through Western blotting.

    Results: Virulent genes were significantly downregulated in single species biofilms when they were treated with Bk+G combination. However, Bk+G did not have significant effect on ALS1 and HWP1 gene in polymicrobial biofilms. ALS3 and SAP5 were significantly downregulated in Bk+G treated polymicrobial biofilm. Similar results were portrayed in Western blotting.

    Conclusion: Bk+G combination exhibited antimicrobial effects against single and mixed species biofilms. The findings might provide insights for treating resistant candida infections. This combination could potentially serve as an herbal alternative to traditional antifungals following further research.

  11. Woon JS, Mackeen MM, Illias RM, Mahadi NM, Broughton WJ, Murad AMA, et al.
    PeerJ, 2017;5:e3909.
    PMID: 29038760 DOI: 10.7717/peerj.3909
    BACKGROUND: Aspergillus niger, along with many other lignocellulolytic fungi, has been widely used as a commercial workhorse for cellulase production. A fungal cellulase system generally includes three major classes of enzymes i.e., β-glucosidases, endoglucanases and cellobiohydrolases. Cellobiohydrolases (CBH) are vital to the degradation of crystalline cellulose present in lignocellulosic biomass. However, A. niger naturally secretes low levels of CBH. Hence, recombinant production of A. niger CBH is desirable to increase CBH production yield and also to allow biochemical characterisation of the recombinant CBH from A. niger.

    METHODS: In this study, the gene encoding a cellobiohydrolase B (cbhB) from A. niger ATCC 10574 was cloned and expressed in the methylotrophic yeast Pichia pastoris X-33. The recombinant CBHB was purified and characterised to study its biochemical and kinetic characteristics. To evaluate the potential of CBHB in assisting biomass conversion, CBHB was supplemented into a commercial cellulase preparation (Cellic(®) CTec2) and was used to hydrolyse oil palm empty fruit bunch (OPEFB), one of the most abundant lignocellulosic waste from the palm oil industry. To attain maximum saccharification, enzyme loadings were optimised by response surface methodology and the optimum point was validated experimentally. Hydrolysed OPEFB samples were analysed using attenuated total reflectance FTIR spectroscopy (ATR-FTIR) to screen for any compositional changes upon enzymatic treatment.

    RESULTS: Recombinant CBHB was over-expressed as a hyperglycosylated protein attached to N-glycans. CBHB was enzymatically active towards soluble substrates such as 4-methylumbelliferyl-β-D-cellobioside (MUC), p-nitrophenyl-cellobioside (pNPC) and p-nitrophenyl-cellobiotrioside (pNPG3) but was not active towards crystalline substrates like Avicel(®) and Sigmacell cellulose. Characterisation of purified CBHB using MUC as the model substrate revealed that optimum catalysis occurred at 50 °C and pH 4 but the enzyme was stable between pH 3 to 10 and 30 to 80 °C. Although CBHB on its own was unable to digest crystalline substrates, supplementation of CBHB (0.37%) with Cellic(®) CTec2 (30%) increased saccharification of OPEFB by 27%. Compositional analyses of the treated OPEFB samples revealed that CBHB supplementation reduced peak intensities of both crystalline cellulose Iα and Iβ in the treated OPEFB samples.

    DISCUSSION: Since CBHB alone was inactive against crystalline cellulose, these data suggested that it might work synergistically with other components of Cellic(®) CTec2. CBHB supplements were desirable as they further increased hydrolysis of OPEFB when the performance of Cellic(®) CTec2 was theoretically capped at an enzyme loading of 34% in this study. Hence, A. niger CBHB was identified as a potential supplementary enzyme for the enzymatic hydrolysis of OPEFB.

  12. Brückner A, Klompen H, Bruce AI, Hashim R, von Beeren C
    PeerJ, 2017;5:e3870.
    PMID: 29038753 DOI: 10.7717/peerj.3870
    A great variety of parasites and parasitoids exploit ant societies. Among them are the Mesostigmata mites, a particularly common and diverse group of ant-associated arthropods. While parasitism is ubiquitous in Mesostigmata, parasitoidism has only been described in the genus Macrodinychus. Yet information about the basic biology of most Macrodinychus species is lacking. Out of 24 formally described species, information about basic life-history traits is only available for three species. Here we formally describe two new Macrodinychus species, i.e. Macrodinychus hilpertae and Macrodinychus derbyensis. In both species, immature stages developed as ecto-parasitoids on ant pupae of the South-East Asian army ant Leptogenys distinguenda. By piercing the developing ant with their chelicera, the mites apparently suck ant hemolymph, ultimately killing host individuals. We compare infection rates among all studied Macrodinychus species and discuss possible host countermeasures against parasitoidism. The cryptic lifestyle of living inside ant nests has certainly hampered the scientific discovery of Macrodinychus mites and we expect that many more macrodinychid species await scientific discovery and description.
  13. Takafumi H, Kamii T, Murai T, Yoshida R, Sato A, Tachiki Y, et al.
    PeerJ, 2017;5:e3869.
    PMID: 29038752 DOI: 10.7717/peerj.3869
    The sika deer (Cervus nippon yesoensis) population in the Ramsar-listed Kushiro Wetland has increased in recent years, and the Ministry of the Environment of Japan has decided to take measures to reduce the impact of deer on the ecosystem. However, seasonal movement patterns of the deer (i.e., when and where the deer inhabit the wetland) remain unclear. We examined the seasonal movement patterns of sika deer in the Kushiro Wetland from 2013 to 2015 by analyzing GPS location data for 28 hinds captured at three sites in the wetland. Seasonal movement patterns were quantitatively classified as seasonal migration, mixed, dispersal, nomadic, resident, or atypical, and the degree of wetland utilization for each individual was estimated. The area of overlap for each individual among intra-capture sites and inter-capture sites was calculated for the entire year and for each season. Our results showed that the movement patterns of these deer were classified not only as resident but also as seasonal migration, dispersal, and atypical. Approximately one-third of the individuals moved into and out of the wetland during the year as either seasonal migrants or individuals with atypical movement. Some of the individuals migrated to farmland areas outside the wetland (the farthest being 69.9 km away). Half of the individuals inhabited the wetland all or most of the year, i.e., 81-100% of their annual home range was within the wetland area. Even among individuals captured at the same site, different seasonal movement patterns were identified. The overlap areas of the home ranges of individuals from the same capture sites were larger than those for individuals from different capture sites (e.g., mean of annual home range overlap with intra-capture sites: 47.7% vs. inter-sites: 1.3%). To achieve more effective ecosystem management including deer management in the wetland, management plans should cover inside and outside of the wetland and separate the population into multiple management units to address the different movement patterns and wetland utilization of the population.
  14. Jindal HM, Zandi K, Ong KC, Velayuthan RD, Rasid SM, Samudi Raju C, et al.
    PeerJ, 2017;5:e3887.
    PMID: 29018620 DOI: 10.7717/peerj.3887
    BACKGROUND: Antimicrobial peptides (AMPs) are of great potential as novel antibiotics for the treatment of broad spectrum of pathogenic microorganisms including resistant bacteria. In this study, the mechanisms of action and the therapeutic efficacy of the hybrid peptides were examined.

    METHODS: TEM, SEM and ATP efflux assay were used to evaluate the effect of hybrid peptides on the integrity of the pneumococcal cell wall/membrane. DNA retardation assay was assessed to measure the impact of hybrid peptides on the migration of genomic DNA through the agarose gel. In vitro synergistic effect was checked using the chequerboard assay. ICR male mice were used to evaluate the in vivo toxicity and antibacterial activity of the hybrid peptides in a standalone form and in combination with ceftriaxone.

    RESULTS: The results obtained from TEM and SEM indicated that the hybrid peptides caused significant morphological alterations in Streptococcus pneumoniae and disrupting the integrity of the cell wall/membrane. The rapid release of ATP from pneumococcal cells after one hour of incubation proposing that the antibacterial action for the hybrid peptides is based on membrane permeabilization and damage. The DNA retardation assay revealed that at 62.5 µg/ml all the hybrid peptides were capable of binding and preventing the pneumococcal genomic DNA from migrating through the agarose gel. In vitro synergy was observed when pneumococcal cells treated with combinations of hybrid peptides with each other and with conventional drugs erythromycin and ceftriaxone. The in vivo therapeutic efficacy results revealed that the hybrid peptide RN7-IN8 at 20 mg/kg could improve the survival rate of pneumococcal bacteremia infected mice, as 50% of the infected mice survived up to seven days post-infection. In vivo antibacterial efficacy of the hybrid peptide RN7-IN8 was signficantly improved when combined with the standard antibiotic ceftriaxone at (20 mg/kg + 20 mg/kg) as 100% of the infected mice survived up to seven days post-infection.

    DISCUSSION: Our results suggest that attacking and breaching the cell wall/membrane is most probably the principal mechanism for the hybrid peptides. In addition, the hybrid peptides could possess another mechanism of action by inhibiting intracellular functions such as DNA synthesis. AMPs could play a great role in combating antibiotic resistance as they can reduce the therapeutic concentrations of standard drugs.

  15. Cheng KS, Chang YF, Han RPS, Lee PF
    PeerJ, 2017;5:e3857.
    PMID: 29018605 DOI: 10.7717/peerj.3857
    OBJECTIVES: Practitioners of mindfulness are reported to have greater cognitive control especially in conflict monitoring, response inhibition and sustained attention. However, due to the various existing methods in each mindfulness practices and also, the high commitment factor, a barrier still exists for an individual to pick up the practices. Therefore, the effect of short duration deep breathing on the cognitive control is investigated here.

    METHODS: Short duration guided deep breathing videos consisting of 5, 7 and 9 min respectively were created and used on subjects training. The effect on cognitive control was assessed using a Go/NoGo task along with event-related potential (ERP) measurements at Fz, Cz, and Pz.

    RESULTS: From the study, the significant outcome showed at the follow-up session in which participants engaged for 5 min deep breathing group showed a profound NoGo N2 amplitude increment as compared to the control group, indicating an enhanced conflict monitoring ability. An inverse relationship between the NoGo N2 amplitude and the breathing duration is observed as well at the follow-up session.

    CONCLUSION: These results indicated the possibility of performing short duration deep breathing guided by a video to achieve an enhanced conflict monitoring as an alternative to other mindfulness practices and 5 min is found to be the optimum practice duration.

    SIGNIFICANT: This study is the first to establish a relationship between deep breathing and conflict monitoring through ERP. The study population of young adults taken from the same environment reduces the variance in ERP results due to age and environment.

    LIMITATION: A larger sample size would provide a greater statistical power. A longer duration of deep breathing should be investigated to further clarify the relationship between the practice duration and the NoGo N2 amplitude. The result can be split by gender and analyzed separately due to the different brain structure of males and females.

  16. Ożgo M, Liew TS, Webster NB, Schilthuizen M
    PeerJ, 2017;5:e3938.
    PMID: 29093997 DOI: 10.7717/peerj.3938
    Natural history collections are an important and largely untapped source of long-term data on evolutionary changes in wild populations. Here, we utilize three large geo-referenced sets of samples of the common European land-snail Cepaea nemoralis stored in the collection of Naturalis Biodiversity Center in Leiden, the Netherlands. Resampling of these populations allowed us to gain insight into changes occurring over 95, 69, and 50 years. Cepaea nemoralis is polymorphic for the colour and banding of the shell; the mode of inheritance of these patterns is known, and the polymorphism is under both thermal and predatory selection. At two sites the general direction of changes was towards lighter shells (yellow and less heavily banded), which is consistent with predictions based on on-going climatic change. At one site no directional changes were detected. At all sites there were significant shifts in morph frequencies between years, and our study contributes to the recognition that short-term changes in the states of populations often exceed long-term trends. Our interpretation was limited by the few time points available in the studied collections. We therefore stress the need for natural history collections to routinely collect large samples of common species, to allow much more reliable hind-casting of evolutionary responses to environmental change.
  17. Karin BR, Das I, Jackman TR, Bauer AM
    PeerJ, 2017;5:e3762.
    PMID: 29093993 DOI: 10.7717/peerj.3762
    Episodic sea level changes that repeatedly exposed and inundated the Sunda Shelf characterize the Pleistocene. Available evidence points to a more xeric central Sunda Shelf during periods of low sea levels, and despite the broad land connections that persisted during this time, some organisms are assumed to have faced barriers to dispersal between land-masses on the Sunda Shelf. Eutropis rugifera is a secretive, forest adapted scincid lizard that ranges across the Sunda Shelf. In this study, we sequenced one mitochondrial (ND2) and four nuclear (BRCA1, BRCA2, RAG1, and MC1R) markers and generated a time-calibrated phylogeny in BEAST to test whether divergence times between Sundaic populations of E. rugifera occurred during Pleistocene sea-level changes, or if they predate the Pleistocene. We find that E. rugifera shows pre-Pleistocene divergences between populations on different Sundaic land-masses. The earliest divergence within E. rugifera separates the Philippine samples from the Sundaic samples approximately 16 Ma; the Philippine populations thus cannot be considered conspecific with Sundaic congeners. Sundaic populations diverged approximately 6 Ma, and populations within Borneo from Sabah and Sarawak separated approximately 4.5 Ma in the early Pliocene, followed by further cladogenesis in Sarawak through the Pleistocene. Divergence of peninsular Malaysian populations from the Mentawai Archipelago occurred approximately 5 Ma. Separation among island populations from the Mentawai Archipelago likely dates to the Pliocene/Pleistocene boundary approximately 3.5 Ma, and our samples from peninsular Malaysia appear to coalesce in the middle Pleistocene, about 1 Ma. Coupled with the monophyly of these populations, these divergence times suggest that despite consistent land-connections between these regions throughout the Pleistocene E. rugifera still faced barriers to dispersal, which may be a result of environmental shifts that accompanied the sea-level changes.
  18. Phung CC, Heng PS, Liew TS
    PeerJ, 2017;5:e3981.
    PMID: 29104827 DOI: 10.7717/peerj.3981
    Leptopoma is a species rich genus with approximately 100 species documented. Species-level identification in this group has been based on shell morphology and colouration, as well as some anatomical features based on small sample sizes. However, the implications of the inter- and intra-species variations in shell form to the taxonomy of Leptopoma species and the congruency of its current shell based taxonomy with its molecular phylogeny are still unclear. There are four Leptopoma species found in Sabah, Borneo, and their taxonomy status remains uncertain due to substantial variation in shell forms. This study focuses on the phylogenetic relationships and geographical variation in shell form of three Leptopoma species from Sabah. The phylogenetic relationship of these species was first estimated by performing Maximum Likelihood and Bayesian analysis based on mitochondrial genes (16S rDNA and COI) and nuclear gene (ITS-1). Then, a total of six quantitative shell characters (i.e., shell height, shell width, aperture height, aperture width, shell spire height, and ratio of shell height to width) and three qualitative shell characters (i.e., shell colour patterns, spiral ridges, and dark apertural band) of the specimens were mapped across the phylogenetic tree and tested for phylogenetic signals. Data on shell characters of Leptopoma sericatum and Leptopoma pellucidum from two different locations (i.e., Balambangan Island and Kinabatangan) where both species occurred sympatrically were then obtained to examine the geographical variations in shell form. The molecular phylogenetic analyses suggested that each of the three Leptopoma species was monophyletic and indicated congruence with only one of the shell characters (i.e., shell spiral ridges) in the current morphological-based classification. Although the geographical variation analyses suggested some of the shell characters indicating inter-species differences between the two Leptopoma species, these also pointed to intra-species differences between populations from different locations. This study on Leptopoma species is based on small sample size and the findings appear only applicable to Leptopoma species in Sabah. Nevertheless, we anticipate this study to be a starting point for more detailed investigations to include the other still little-known (ca. 100) Leptopoma species and highlights a need to assess variations in shell characters before they could be used in species classification.
  19. Ali NM, Khan HA, Then AY, Ving Ching C, Gaur M, Dhillon SK
    PeerJ, 2017;5:e3811.
    PMID: 28929028 DOI: 10.7717/peerj.3811
    Life science ontologies play an important role in Semantic Web. Given the diversity in fish species and the associated wealth of information, it is imperative to develop an ontology capable of linking and integrating this information in an automated fashion. As such, we introduce the Fish Ontology (FO), an automated classification architecture of existing fish taxa which provides taxonomic information on unknown fish based on metadata restrictions. It is designed to support knowledge discovery, provide semantic annotation of fish and fisheries resources, data integration, and information retrieval. Automated classification for unknown specimens is a unique feature that currently does not appear to exist in other known ontologies. Examples of automated classification for major groups of fish are demonstrated, showing the inferred information by introducing several restrictions at the species or specimen level. The current version of FO has 1,830 classes, includes widely used fisheries terminology, and models major aspects of fish taxonomy, grouping, and character. With more than 30,000 known fish species globally, the FO will be an indispensable tool for fish scientists and other interested users.
  20. Chew CH, Lim YAL, Chua KH
    PeerJ, 2017;5:e3794.
    PMID: 28929019 DOI: 10.7717/peerj.3794
    BACKGROUND: Plasmodium is an obligate intracellular parasite. Apical membrane antigen 1 (AMA1) is the most prominent and well characterized malarial surface antigen that is essential for parasite-host cell invasion, i.e., for sporozoite to invade and replicate within hepatocytes in the liver stage and merozoite to penetrate and replicate within erythrocytes in the blood stage. AMA1 has long served as a potent antimalarial drug target and is a pivotal vaccine candidate. A good understanding of the structure and molecular function of this Plasmodium protein, particularly its involvement in host-cell adhesion and invasion, is of great interest and hence it offers an attractive target for the development of novel therapeutics. The present study aims to heterologous express recombinant Plasmodium AMA1 ectodomain of P. vivax (rPvAMA1) for the selection of binding peptides.

    METHODS: The rPvAMA1 protein was heterologous expressed using a tag-free Profinity eXact(TM) system and codon optimized BL21-Codon Plus (DE3)-RIL Escherichia coli strain and further refolded by dialysis for renaturation. Binding peptides toward refolded rPvAMA1 were panned using a Ph.D.-12 random phage display library.

    RESULTS: The rPvAMA1 was successfully expressed and refolded with three phage-displayed dodecapeptides designated as PdV1 (DLTFTVNPLSKA), PdV2 (WHWSWWNPNQLT), and PdV3 (TSVSYINNRHNL) with affinity towards rPvAMA1 identified. All of them exhibited positive binding signal to rPvAMA1 in both direct phage assays, i.e., phage ELISA binding assay and Western blot binding assay.

    DISCUSSION: Phage display technology enables the mapping of protein-protein interactions based on a simple principle that a library of phage particles displaying peptides is used and the phage clones that bind to the target protein are selected and identified. The binding sites of each selected peptides toward PvAMA1 (Protein Data Bank, PDB ID: 1W8K) were in silico predicted using CABS-dock web server. In this case, the binding peptides provide a valuable starting point for the development of peptidomimetic as antimalarial antagonists directed at PvAMA1.

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