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  1. Tan KH, Tan JY, Yin WF, Chan KG
    PeerJ, 2015;3:e1216.
    PMID: 26355540 DOI: 10.7717/peerj.1216
    Cedecea neteri is a very rare human pathogen. We have isolated a strain of C. neteri SSMD04 from pickled mackerel sashimi identified using molecular and phenotypics approaches. Using the biosensor Chromobacterium violaceum CV026, we have demonstrated the presence of short chain N-acyl-homoserine lactone (AHL) type quorum sensing (QS) activity in C. neteri SSMD04. Triple quadrupole LC/MS analysis revealed that C. neteri SSMD04 produced short chain N-butyryl-homoserine lactone (C4-HSL). With the available genome information of C. neteri SSMD04, we went on to analyse and identified a pair of luxI/R homologues in this genome that share the highest similarity with croI/R homologues from Citrobacter rodentium. The AHL synthase, which we named cneI(636 bp), was found in the genome sequences of C. neteri SSMD04. At a distance of 8bp from cneI is a sequence encoding a hypothetical protein, potentially the cognate receptor, a luxR homologue which we named it as cneR. Analysis of this protein amino acid sequence reveals two signature domains, the autoinducer-binding domain and the C-terminal effector which is typical characteristic of luxR. In addition, we found that this genome harboured an orphan luxR that is most closely related to easR in Enterobacter asburiae. To our knowledge, this is the first report on the AHL production activity in C. neteri, and the discovery of its luxI/R homologues, the orphan receptor and its whole genome sequence.
  2. Tan WF, Voo SYM, Tan WC, Sandhya R
    Med J Malaysia, 2022 Nov;77(6):669-675.
    PMID: 36448383
    INTRODUCTION: Sweet's syndrome (SS) also known as acute febrile neutrophilic dermatosis, is an uncommon disease characterised by acute onset of tender, violaceous or erythematous, oedematous papules, nodules or plaques, with fever. It is classified into classic, malignancyassociated, and drug-induced subtypes.The aims of this study is to evaluate the subtypes, clinical features, laboratory profiles, and treatment of patients with SS.

    MATERIALS AND METHODS: We did a retrospective medical record review of all patients with SS from July 2014 to July 2018 at Hospital Queen Elizabeth and Hospital Pulau Pinang, both tertiary hospitals in Malaysia.

    RESULTS: Twenty-nine patients were included. Approximately half of the patients (15) were females with a mean age of onset of 50.93 (± 11.52) years. The most common subtype was classic (62.0%) followed by malignancy-associated (31.0%) and drug-induced (6.9%). Among the patients with the classic subtype, infective-related causes (50.0%) were the most common. Among the patients with malignancy, eight had haematological malignancy and one had a solid tumour. Two-third of the malignancies were diagnosed within a year after the diagnosis of SS. Eight of our patients in Sabah had mycobacterial infections with three having concomitant haematological malignancies. Patients with malignancy-associated SS had lower mean haemoglobin (p=0.018) and mean platelet count (p=0.031). Itch was associated with the presence of pustules (p=0.038). Histopathological examination of all skin lesions showed dermal neutrophilic infiltrates and 25 (86.2%) of them had papillary dermal oedema. The study was limited by its retrospective design. The sample size was small likely due to the uncommon occurrence of this condition.

    CONCLUSION: SS is an uncommon dermatosis with distinctive clinical and histopathological features. Screening for underlying malignancy is essential especially for those who present with anaemia, thrombocytopenia, and pathergy phenomenon. Mycobacterial infection should be considered in this region due to high tuberculosis burden.

  3. Tan MP, Mohamed Alitheen NB, Tan WS, Yap WB
    Vaccines (Basel), 2022 Dec 01;10(12).
    PMID: 36560475 DOI: 10.3390/vaccines10122066
    The current influenza vaccines only confer protection against the circulating influenza subtypes, therefore universal vaccines are needed to prevent upcoming influenza outbreaks caused by emerging influenza subtypes. The extracellular domain of influenza A M2 protein (M2e) is highly conserved among different subtypes of influenza A viruses, and it is able to elicit protective immunity against the viruses. The influenza nucleoprotein (NP) was used to display the M2e in this study due to its promising T-cell response and adjuvanticity. The M2e gene was fused to the 5'-end of the NP gene and then cloned into pRSET B vector. The DNA sequencing analysis revealed six point mutations in the M2e-NP fusion gene, including one mutation in the M2e peptide and five mutations in the NP. The mutations were reverted using PCR site-directed mutagenesis. The recombinant plasmids (pRSET B-M2e-NP and pRSET B-mM2e-NP) were introduced into Escherichia coli (E. coli) BL21 (DE3) for protein expression. The mutated and non-mutated proteins were subsequently expressed and named mM2e-NP and M2e-NP, respectively. The expression of mM2e-NP and M2e-NP was not affected by the mutations. The binding of anti-M2e antibody to the purified native mM2e-NP and M2e-NP also remained active. However, when the anti-NP antibody was tested, the signal produced by mM2e-NP was very weak. The results implied that the amino acid changes in the NP had adversely impacted on the conformation of mM2e-NP and subsequently affected the antibody binding. In light of the remarkable antibody binding to the M2e-NP fusion protein, this study highly recommends the potential of M2e-NP as a universal influenza vaccine candidate.
  4. Tan EW, Simon SE, Numan A, Khalid M, Tan KO
    Colloids Surf B Biointerfaces, 2024 Mar;235:113793.
    PMID: 38364521 DOI: 10.1016/j.colsurfb.2024.113793
    Breast cancer is a global health concern that requires personalized therapies to prevent relapses, as conventional treatments may develop resistance over time. Photothermal therapy using spectral radiation or intense light emission is a broad-spectrum treatment that induces hyperthermia-mediated cancer cell death. MXene, a two-dimensional material, has been reported to have potential biological applications in photothermal therapy for cancer treatment. In this study, we investigated the apoptotic activity of MXene and UV-irradiated MXene in MCF-7 breast cancer cells by treating them with varying concentrations of MXene. The cytotoxicity of MXene and UV was evaluated by analyzing cellular morphology, nuclei condensation, caspase activation, and apoptotic cell death. We also assessed the effect of the combined treatment on the expression and cellular distribution of Tubulin, a key component of microtubules required for cell division. At low concentrations of MXene (up to 100 µg/ml), the level of cytotoxicity in MCF-7 cells was low. However, the combined treatment of MXene and UV resulted in a synergistic increase in cytotoxicity, causing rounded cellular morphology, condensed nuclei, caspase activation, and apoptotic cell death. Furthermore, the treatment reduced Tubulin protein expression and cellular distribution, indicating a potent inducer of cell death with potential application for cancer treatment. The study demonstrates that the combined treatment of MXene and UVB irradiation is a promising strategy for inducing apoptotic cell death in breast cancer cells, suggesting its potential as a therapeutic intervention for breast cancer.
  5. Wee SL, Tan SB, Tan SH, Lee BKB
    J Plant Res, 2024 May;137(3):423-443.
    PMID: 38353931 DOI: 10.1007/s10265-024-01522-7
    Despite being the world's largest single-flower, Rafflesia's biology and life history are still poorly understood due to its cryptic growth strategy on Tetrastigma vines. Previous studies have been mostly short-term, contrary to Rafflesia's long development period before blooming. Bud development and flower phenology of R. cantleyi was studied in a dipterocarp forest in Lata Jarum, Peninsular Malaysia. Seven populations, consisting of 247 buds, were monitored fortnightly for 65 months in two discrete studies between 2009 and 2018. The bud size distribution of R. cantleyi is dynamic, progressively changing from small flower buds to larger buds before flowering. Buds  15.0 cm across demonstrated accelerated growth. The bud growth profiles of the same site clustered distinctively regardless of sex with successful blooming rate that varied greatly between sites, prompting speculation about their relatedness to the sites' physical attributes. We reported the first female-dominated population in Rafflesia's life history. Rafflesia cantleyi's blooming rate at Lata Jarum is moderate to high, with non-seasonal flowering phenology as evident by the lack of synchronisation and consistency between flowering and local rainfall patterns. Based on the field data of the present study and the published information of other Rafflesia species, R. cantleyi's life cycle was estimated between 4.0 and 5.3 years. Our findings further explain Rafflesia's biology and life history and highlight the gap in knowledge of the natural habitats on the endoparasite's growth and fate potentially for future conservation and study.
  6. Zhang D, Tan WH, Wei Y, Tan CK
    Front Artif Intell, 2024;7:1295554.
    PMID: 38978998 DOI: 10.3389/frai.2024.1295554
    The panoramic stereo video has brought a new visual experience for the audience with its immersion and stereo effect. In panoramic stereo video, the face is an important element. However, the face image in panoramic stereo video has varying degrees of deformation. This brings new challenges to face recognition. Therefore, this paper proposes a face recognition model DCM2Net (Deformable Convolution MobileFaceNet) for panoramic stereo video. The model mainly integrates the feature information between channels during feature fusion, redistributes the information between channels in the deeper part of the network, and fully uses the information between different channels for feature extraction. This paper also built a panoramic stereo video live system, using the DCM2Net model to recognize the face in panoramic stereo video, and the recognition results are displayed in the video. After experiments on different datasets, the results show that our model has better results on popular datasets and panoramic datasets.
  7. Cong CW, Tan SA, Nainee S, Tan CS
    PMID: 35206628 DOI: 10.3390/ijerph19042440
    Family functioning has been associated with psychological well-being and physical health. The 12-item McMaster Family Assessment Device-General Functioning Subscale (FAD-GF) has been widely used to assess individuals' overall level of family functioning. However, it has shown an inconsistent factor structure across various studies. The present study investigated its psychometric qualities in two studies with two different adult samples in Malaysia. In Study 1 (N = 417, 55.3% females, 19 to 26 years old), exploratory factor analyses were conducted, and four models were found: a three-factor model with 11 items, a two-factor model with 12 items, and one-factor models with six negatively worded items and six positively worded items, respectively. Study 2 (N = 358, 65.1% females, 18 to 60 years old) compared models found in past studies and those found in Study 1 through confirmatory factor analyses on another sample of adults. Among the six competing models, the two-factor model with three positively worded and three negatively worded items (i.e., FAD-GF-SF) is preferable because it did not require modification and showed a clear-cut result of goodness of fit. The subscales demonstrated satisfactory internal consistency. In conclusion, the FAD-GF-SF is a useful instrument for measuring family functioning in the Malaysian context.
  8. Tan SH, Yap YY, Tan SK, Wong CK
    JMIR Aging, 2025 Mar 24;8:e60936.
    PMID: 40126531 DOI: 10.2196/60936
    BACKGROUND: The aging population and the accompanying rise in chronic diseases have intensified the need to study the adoption of telehealth services. However, the success of telehealth services depends not only on their ease and usefulness but also on addressing broader concerns. Despite being a substantial user group in traditional health services, older adults may encounter barriers to adopting telehealth services. Increasing the adoption of telehealth among the older adult population is crucial for enhancing their access to care and managing the challenges of aging effectively.

    OBJECTIVE: We aimed to explore factors influencing the adoption of telehealth services among older adults in Malaysia, going beyond the conventional framework by incorporating transition cost and subjective well-being as additional constructs.

    METHODS: A cross-sectional survey was conducted among 119 adults aged ≥60 years in Malaysia, using 39 survey items adapted from existing studies. Data analysis was performed using partial least squares structural equation modeling, with both the measurement model and structural model being evaluated. To determine the predictive relevance of the model, PLSpredict was applied. In addition, importance-performance map analysis was conducted to further expand on the structural model results by assessing the performance of each variable.

    RESULTS: Of the 119 participants, 52 (43.7%) were women and 67 (56.3%) were men. The study found that subjective well-being (β=0.448; P

  9. Beugnet F, Tan YM, Tan DY, Tanrattana C, Taweethavonsawat P
    Vet Parasitol, 2026 Dec;348:110926.
    PMID: 42735466 DOI: 10.1016/j.vetpar.2026.110926
    This open-label, uncontrolled field study evaluated the efficacy and safety of a topical combination of esafoxolaner, eprinomectin, and praziquantel (at minimum doses of 1.4 mg/kg, 0.5 mg/kg, and 5 mg/kg, respectively) for the treatment of natural infestations with Lynxacarus radovskyi in 16 privately owned cats. Cats were recruited from three veterinary clinics based on inclusion criteria requiring confirmed L. radovskyi infestation and clinically healthy, with the exception of varying degrees of infestation-associated dermatological signs, including pruritus, alopecia, and scaling, were present at enrollment. All cats received a single topical treatment and served as their own controls; no negative untreated control group was included. Parasitological efficacy was assessed using semi-quantitative mite scoring, and clinical response was evaluated using lesion scores for pruritus, alopecia, and desquamation on Days 0, 15, and 30. The topical esafoxolaner treatment demonstrated 100% parasitological efficacy, with all cats free of detectable mites by Day 30 using semi-quantitative counting. Clinical signs improved markedly during the study period, and no adverse events were observed.
  10. Tan YL, Yiew TH, Lau LS, Tan AL
    Environ Sci Pollut Res Int, 2022 Sep;29(42):64004-64021.
    PMID: 35467185 DOI: 10.1007/s11356-022-20090-8
    This study aims to explore the income-biodiversity loss nexus in South and Southeast Asian countries covering the period between 2013 and 2019. Negative Binomial regression models are used to deal with the count regressand variable with specific emphasis on different taxonomic groups of threatened species, namely, mammal, bird, reptile, amphibian, fish, mollusk, other invertebrate, plant, and total threatened species. We find strong support of an inverted U-shaped relationship between income and biodiversity loss in all taxonomic groups of threatened species examined. Additionally, agricultural land has a significant and positive effect on biodiversity loss. Control of corruption and biodiversity loss are found to be negatively associated. The inverted U-shaped EKC suggests that South and Southeast Asian countries are required to identify policy priority areas that could achieve robust economic growth while reducing biodiversity loss. Our findings also provide valuable policy insights to assist the policy makers to better cope with the problem of biodiversity loss via corruption control and agricultural land use.
  11. Tan CH, Palasuberniam P, Pernee LL, Tan KY
    PLoS Negl Trop Dis, 2026 May;20(5):e0013859.
    PMID: 42133734 DOI: 10.1371/journal.pntd.0013859
    Short-chain α-neurotoxins (SNTXs) are the principal neurotoxic components in several Asiatic cobras, including Naja atra, Naja philippinensis, and Naja samarensis. Although structurally conserved, SNTXs exhibit marked antigenic variation that can limit the effectiveness of regional antivenoms used for snakebite envenoming in Asia. Here, we evaluated the immunoreactivity of the Philippine Cobra Antivenom (PCAV) and three regional products-Naja kaouthia Monovalent Antivenom (NkMAV), Neuro Bivalent Antivenom (NBAV), and Indonesian SABU-against a panel of cobra venoms and purified α-neurotoxins. PCAV bound strongly to homologous N. philippinensis SNTX but showed significantly lower cross-reactivity with SNTXs from Naja kaouthia, Naja sputatrix, and N. atra, and minimal recognition of marine elapid SNTXs and long-chain α-neurotoxins (LNTXs) of Monocled Cobra as well as King Cobra. Conversely, NkMAV and NBAV recognized mainland Asian SNTXs more broadly but reacted poorly with the Philippine cobra toxin. These differences were statistically significant in multiple comparisons versus the homologous venom control. Hierarchical clustering of normalized immunoreactivity delineated two major SNTX antigenic subtypes corresponding to Philippine versus continental Asian lineages. Peptide sequence analysis unmasked two distinct loop-II motifs (28WWS-TII37 and 28RWR-YRT37) associated with these divergent immunotypes. Phylogenetic reconstruction suggests that the Philippine cobras retain an ancestral-like SNTX motif, while Sundaic and East Asian cobras have diversified to employ another major SNTX form. Epitope prediction further revealed differences in surface exposure and accessibility, which helps explain the limited cross-neutralization among antivenoms. These findings demonstrate a clear antigenic dichotomy among Asian cobra SNTXs, which underlies species-specific antivenom effectiveness and highlights the need to incorporate representative SNTX variants into immunogen formulations to improve regional antivenom coverage.
  12. Hew SY, Tan PY, Zhao K, Tan HY
    Curr Microbiol, 2025 Mar 07;82(4):175.
    PMID: 40053104 DOI: 10.1007/s00284-025-04137-w
    Economic sustainability and the emergence of infectious diseases remain critical challenges in tilapia aquaculture. Lactic acid bacteria (LAB) are well-known feed additives with probiotic effects in improving overall performance of livestock. This study evaluated the effects of host-associated probiotic, Leuconostoc lactis TARicum AI2, on growth performance, antioxidant, immune responses, and gut microbiota of red hybrid tilapia (Oreochromis sp.) by conducting an 86-day feeding trial. The probiotic, previously characterised for its beneficial traits, was coated on commercial feed at a concentration of 109 CFU g-1. Results showed tilapia fed with probiotic had significant improvement in feed conversion ratio (FCR) and protein efficiency ratio (PER) compared to the control group. Upregulation of cytokine expressions was observed in the probiotic group. Gut microbiota analysis revealed an increased abundance of the genera Clostridium and Leuconostoc in the probiotic-fed tilapia. Beta-diversity indices proved exclusive groups of bacteria present in specific diet only. In conclusion, L. lactis strain TARicum AI2 is a potential probiotic candidate in promoting growth in tilapia as the results suggested it could improve FCR and PER. Feed with lower FCR and higher PER could help tilapia farmers in reducing feed cost, which accounted for the major portion of their production cost. This further enables them to achieve cost-effective, enhanced productivity and economic sustainability in a long run.
  13. Wong KY, Tan CH, Tan KY, Quraishi NH, Tan NH
    J Proteomics, 2018 03 20;175:156-173.
    PMID: 29278784 DOI: 10.1016/j.jprot.2017.12.012
    Naja naja is a medically important species that is distributed widely in South Asia. Its venom lethality and neutralization profile have been reported to vary markedly, but the understanding of this phenomenon has been limited without a comprehensive venom profile for the Pakistani N. naja. This study set to investigate the venom proteome of Pakistani N. naja applying reverse-phase HPLC, SDS-PAGE, mass spectrometry and data-mining approaches. The venom enzymatics and antigen binding activities were also studied. A total of 55 venom proteins comprising 11 toxin families were identified, with three-finger toxins (75.29%) being the predominant component, followed by phospholipase A2 (14.24%) and other proteins (<5%). The enzyme activities of most of the venom components were also detected in this work. The high abundance of long neurotoxins (LNTX, 21.61%) in the Pakistani N. naja venom is varied from that reported for N. naja venoms from other geographical origins. The venom exhibited high immunoreactivity toward Naja kaouthia monovalent antivenom (NKMAV), which was raised against the LNTX-predominated heterologous Thai N. kaouthia venom. Together, the findings show that the Pakistani N. naja venom is predominated by LNTX, and this unique property correlates with its high lethality and effective neutralization by the heterologous NKMAV.

    BIOLOGICAL SIGNIFICANCE: This study reveals the compositional details of the venom proteome of Pakistani spectacled cobra (Naja naja). The protein subtypes, proteoforms, and relative abundances of individual proteins were comprehensively revealed in this study, following a venom decomplexing proteomic approach. The Pakistani cobra venom is unique among the rest of the N. naja venom composition reported thus far, as it contains a high abundance of alpha-neurotoxins (predominated by long neurotoxins); these are highly potent post-synaptic neuromuscular blockers that cause paralysis and are principal toxins that account for the high lethality of the venom (LD50=0.2μg/g in mice). In contrast, previous reports showed that the N. naja venoms of India and Sri Lanka had a lower content of neurotoxins and a relatively higher value of LD50. The Pakistani cobra venom demonstrated sufficient immunoreactivity toward three antivenom products manufactured outside Pakistan (including the Indian product VINS), however the potency of antigen binding was the highest toward Naja kaouthia monovalent antivenom, a heterologous antivenom raised against a long neurotoxin-predominated venom of the Thai monocled cobra. From the practical standpoint, the findings indicate that the treatment of N. naja envenomation in Pakistan may be improved by the production of a locale-specific antivenom, in which the antivenom produced contains more antibodies that can target and react more specifically with the highly abundant lethal neurotoxins in the Pakistani N. naja venom.

  14. Faisal T, Tan KY, Sim SM, Quraishi N, Tan NH, Tan CH
    J Proteomics, 2018 07 15;183:1-13.
    PMID: 29729992 DOI: 10.1016/j.jprot.2018.05.003
    The venom proteome of wild Pakistani Russell's viper (Daboia russelii) was investigated through nano-ESI-LCMS/MS of the reverse-phase HPLC fractions. A total of 54 venom proteins were identified and clustered into 11 protein families. Phospholipase A2 (PLA2, 63.8%) and Kunitz-type serine protease inhibitor (KSPI, 16.0%) were most abundant, followed by snake venom serine protease (SVSP, 5.5%, mainly Factor V activating enzyme), vascular endothelial growth factor (VEGF, 4.3%), snake venom metalloproteinase (SVMP, 2.5%, mainly Factor X activating enzyme) and phosphodiesterase (PDE, 2.5%). Other minor proteins include cysteine-rich secretory protein (CRiSP), snake venom C-type lectin/lectin-like protein (snaclec), nerve growth factor, L-amino acid oxidase and 5'-nucleotidase. PLA2, KSPI, SVSP, snaclec and SVMP are hemotoxic proteins in the venom. The study indicated substantial venom variation in D. russelii venoms of different locales, including 3 Pakistani specimens kept in the USA. The venom exhibited potent procoagulant activity on human plasma (minimum clotting dose = 14.5 ng/ml) and high lethality (rodent LD50 = 0.19 μg/g) but lacked hemorrhagic effect locally. The Indian VINS Polyvalent Antivenom bound the venom immunologically in a concentration-dependent manner. It moderately neutralized the venom procoagulant and lethal effects (normalized potency against lethality = 2.7 mg venom neutralized per g antivenom).

    BIOLOGICAL SIGNIFICANCE: Comprehensive venom proteomes of D. russelii from different locales will facilitate better understanding of the geographical variability of the venom in both qualitative and quantitative terms. This is essential to provide scientific basis for the interpretation of differences in the clinical presentation of Russell's viper envenomation. The study revealed a unique venom proteome of the Pakistani D. russelii from the wild (Indus Delta), in which PLA2 predominated (~60% of total venom proteins). The finding unveiled remarkable differences in the venom compositions between the wild (present study) and the captive specimens reported previously. The integration of toxicity tests enabled the correlation of the venom proteome with the envenoming pathophysiology, where the venom showed potent lethality mediated through coagulopathic activity. The Indian VINS Polyvalent Antivenom (VPAV) showed binding activity toward the venom protein antigens; however the immunorecognition of small proteins and PLA2-dominating fractions was low to moderate. Consistently, the antivenom neutralized the toxicity of the wild Pakistani Russell's viper venom at moderate efficacies. Our results suggest that it may be possible to enhance the Indian antivenom potency against the Pakistani viper venom by the inclusion of venoms from a wider geographical range including that from Pakistan into the immunogen formulation.

  15. Oh AMF, Tan CH, Tan KY, Quraishi NH, Tan NH
    J Proteomics, 2019 02 20;193:243-254.
    PMID: 30385415 DOI: 10.1016/j.jprot.2018.10.016
    The proteome of the Pakistani B. sindanus venom was investigated with reverse-phase HPLC and nano-ESI-LCMS/MS analysis. At least 36 distinct proteins belonging to 8 toxin protein families were identified. Three-finger toxin (3FTx), phospholipase A2 (including β-bungarotoxin A-chains) and Kunitz-type serine protease inhibitor (KSPI) were the most abundant, constituting ~95% of total venom proteins. The other toxin proteins of low abundance are snake venom metalloproteinase (SVMP), L-amino acid oxidase (LAAO), acetylcholinesterase (AChE), vespryn and cysteine-rich secretory protein (CRiSP). The venom was highly lethal to mice with LD50 values of 0.04 μg/g (intravenous) and 0.15 μg/g (subcutaneous). The 3FTx proteins are diverse, comprising kappa-neurotoxins, neurotoxin-like protein, non-conventional toxins and muscarinic toxin-like proteins. Kappa-neurotoxins and β-bungarotoxins represent the major toxins that mediate neurotoxicity in B. sindanus envenoming. Alpha-bungarotoxin, commonly present in the Southeast Asian krait venoms, was undetected. The Indian VINS Polyvalent Antivenom (VPAV) was immunoreactive toward the venom, and it moderately cross-neutralized the venom lethality (potency = 0.25 mg/ml). VPAV was able to reverse the neurotoxicity and prevent death in experimentally envenomed mice, but the recovery time was long. The unique toxin composition of B. sindanus venom may be considered in the formulation of a more effective pan-regional, polyspecific antivenom. BIOLOGICAL SIGNIFICANCE: Bungarus sindanus, an endemic krait species distributed mainly in the Sindh Province of Pakistan is a cause of snake envenomation. Its specific antivenom is, however, lacking. The proteomic study of its venom revealed a substantial presence of κ-bungarotoxins and β-bungarotoxins. The toxin profile corroborates the potent neurotoxicity and lethality of the venom tested in vivo. The heterologous Indian VINS polyvalent antivenom (VPAV) cross-reacted with B. sindanus venom and cross-neutralized the venom neurotoxicity and lethality in mice, albeit the efficacy was moderate. The findings imply that B. sindanus and the phylogenetically related B. caeruleus of India share certain venom epitopes. Research should be advanced to improve the efficacy spectrum of a pan-regional polyspecific antivenom.
  16. Tan KY, Liew JL, Tan NH, Quah ESH, Ismail AK, Tan CH
    J Proteomics, 2019 02 10;192:246-257.
    PMID: 30243938 DOI: 10.1016/j.jprot.2018.09.006
    The Asiatic coral snakes are basal in the phylogeny of coral snakes. Although envenoming by the Asiatic coral snakes is rarely fatal, little is known about their venom properties and variability from the American coral snakes. Integrating reverse-phase high performance liquid chromatography and nano-liquid chromatography-tandem mass spectrometry, we showed that the venom proteome of the Malaysian banded or striped coral snake (Calliophis intestinalis) was composed of mainly phospholipases A2 (PLA2, 43.4%) and three-finger toxins (3FTx, 20.1%). Within 3FTx, the cytotoxins or cardiotoxins (CTX) dominated while the neurotoxins' content was much lower. Its subproteomic details contrasted with the 3FTx profile of most Micrurus sp., illustrating a unique dichotomy of venom phenotype between the Old and the New World coral snakes. Calliophis intestinalis venom proteome was correlated with measured enzymatic activities, and in vivo it was myotoxic but non-lethal to mice, frogs and geckos at high doses (5-10 μg/g). The venom contains species-specific toxins with distinct sequences and antigenicity, and the antibodies raised against PLA2 and CTX of other elapids showed poor binding toward its venom antigens. The unique venom proteome of C. intestinalis unveiled a repertoire of novel toxins, and the toxicity test supported the need for post-bite monitoring of myotoxic complication. SIGNIFICANCE: Malaysian banded or striped coral snake (Calliophis intestinalis) has a cytotoxin (CTX)-predominating venom proteome, a characteristic shared by its congener, the Malayan blue coral snake (Calliophis bivirgata). With little neurotoxins (NTX), it illustrates a CTX/NTX dichotomy of venom phenotype between the Old World and the New World coral snakes. The low toxicity of the venom imply that C. intestinalis bite envenoming can be managed via symptomatic relief of the mild to moderate pain with appropriate analgesia. Systemically, the serum creatine kinase level of patients should be monitored serially for potential complication of myotoxicity. The distinct antigenicity of the venom proteins implies that the empirical use of heterologous antivenom is mostly inappropriate and not recommended.
  17. Tan CH, Wong KY, Chong HP, Tan NH, Tan KY
    J Proteomics, 2019 08 30;206:103418.
    PMID: 31201947 DOI: 10.1016/j.jprot.2019.103418
    The Philippine cobra, Naja philippinensis, is a WHO Category 1 venomous snake of medical importance responsible for fatal envenomation in the northern Philippines. To elucidate the venom proteome and pathophysiology of envenomation, N. philippinensis venom proteins were decomplexed with reverse-phase high-performance liquid chromatography, and protein fractions were subsequently digested with trypsin, followed by nano-liquid chromatography-tandem mass spectrometry analysis and data mining. Three-finger toxins (3FTX, 66.64% of total venom proteins) and phospholipases A2 (PLA2, 22.88%) constitute the main bulk of venom proteome. Other proteins are present at low abundances (<4% each); these include metalloproteinase, serine protease, cobra venom factor, cysteine-rich secretory protein, vespryn, phosphodiesterase, 5' nucleotidase and nerve growth factor. In the three-finger toxin family, the alpha-neurotoxins comprise solely short neurotoxins (SNTX, 44.55%), supporting that SNTX is the principal toxin responsible for neuromuscular paralysis and lethality reported in clinical envenomation. Cytotoxins (CTX) are the second most abundant 3FTX proteins in the venom (21.31%). The presence of CTX correlates with the venom cytotoxic effect, which is more prominent in murine cells than in human cells. From the practical standpoint, SNTX-driven neuromuscular paralysis is significant in N. philippinensis envenomation. Antivenom production and treatment should be tailored accordingly to ensure effective neutralization of SNTX. BIOLOGICAL SIGNIFICANCE: The venom proteome of Naja philippinensis, the Philippine cobra, is unravelled for the first time. Approximately half the protein bulk of the venom is made up of short neurotoxins (44.55% of the total venom proteins). As the only alpha-neurotoxins present in the venom, short neurotoxins are the causative toxins of the post-synaptic blockade and fast-onset neuromuscular paralysis in N. philippinensis envenomation. A substantial amount of cytotoxins (21.31%) was also detected in N. philippinensis venom, supporting that the venom can be cytotoxic although the effect is much weaker in human cells compared to murine cells. The finding is consistent with the low incidence of local tissue necrosis in N. philippinensis envenomation, although this does not negate the need for monitoring and care of bite wound in the patients.
  18. Wang S, Liu F, Tan KS, Ser HL, Tan LT, Lee LH, et al.
    J Cell Mol Med, 2020 01;24(1):722-736.
    PMID: 31680470 DOI: 10.1111/jcmm.14780
    Evidence demonstrates that M1 macrophage polarization promotes inflammatory disease. Here, we discovered that (R)-salbutamol, a β2 receptor agonist, inhibits and reprograms the cellular metabolism of RAW264.7 macrophages. (R)-salbutamol significantly inhibited LPS-induced M1 macrophage polarization and downregulated expressions of typical M1 macrophage cytokines, including monocyte chemotactic protein-1 (MCP-1), interleukin-1β (IL-1β) and tumour necrosis factor α (TNF-α). Also, (R)-salbutamol significantly decreased the production of inducible nitric oxide synthase (iNOS), nitric oxide (NO) and reactive oxygen species (ROS), while increasing the reduced glutathione (GSH)/oxidized glutathione (GSSG) ratio. In contrast, (S)-salbutamol increased the production of NO and ROS. Bioenergetic profiles showed that (R)-salbutamol significantly reduced aerobic glycolysis and enhanced mitochondrial respiration. Untargeted metabolomics analysis demonstrated that (R)-salbutamol modulated metabolic pathways, of which three metabolic pathways, namely, (a) phenylalanine metabolism, (b) the pentose phosphate pathway and (c) glycerophospholipid metabolism were the most noticeably impacted pathways. The effects of (R)-salbutamol on M1 polarization were inhibited by a specific β2 receptor antagonist, ICI-118551. These findings demonstrated that (R)-salbutamol inhibits the M1 phenotype by downregulating aerobic glycolysis and glycerophospholipid metabolism, which may propose (R)-salbutamol as the major pharmacologically active component of racemic salbutamol for the treatment of inflammatory diseases and highlight the medicinal value of (R)-salbutamol.
  19. Tan JH, Sivadurai G, Tan HCL, Tan YR, Jahit S, Hans Alexander M
    Surg Laparosc Endosc Percutan Tech, 2020 Apr;30(2):106-110.
    PMID: 31923160 DOI: 10.1097/SLE.0000000000000754
    BACKGROUND: Provision of enteral nutrition with jejunal feeding in upper gastrointestinal obstruction is highly recommended. Access to jejunum can be obtained surgically, percutaneously, or endoscopically. Our institution routinely and preferentially utilizes a silicone nasojejunal tube that is inserted past the obstruction endoscopically. We use a custom dual channel tube that allows feeding at the distal tip and another channel 40 cm from the tip that enables decompression proximally. This is a report of our experience with this custom nasojejunal tube.

    METHODS: This is a prospective observational study of 201 patients who underwent endoscopic nasojejunal wire-guided feeding tube insertions for obstruction of either the esophagus or the stomach including both benign and malignant pathologies between January 2015 to June 2018 in Hospital Sungai Buloh and Hospital Sultanah Aminah, Malaysia. The indications for tube insertion, insertion technique, and tube-related problems were described.

    RESULTS: The nasojejunal tube was used to establish enteral feeding in patients with obstructing tumors of the distal esophagus in 65 patients (32.3%) and gastric outlet obstruction in 72 patients (35.8%). There were 54 patients (26.9%) who required reinsertion. The most common reason for reinsertion was unintentional dislodgement, where 32 patients (15.9%) followed by tube blockage 20 patients (10.0%). Using our method of advancement under direct vision, we had only 2 cases of malposition due to severely deformed anatomy. We had no incidence of aspiration in this group of patients and overall, the patients tolerated the tube well.

    CONCLUSIONS: The novel nasojejunal feeding tube with gastric decompression function is a safe and effective method of delivery of enteral nutrition in patients with upper gastrointestinal obstruction. These tubes if inserted properly are well tolerated with almost no risk of malposition and are tolerated well even for prolonged periods of time until definitive surgery could be performed.

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