Preliminary Study of Glucose Removal Using Biosorbents from Ananas comosus Leaves

The usefulness of Ananas comosus (pineapple) is not limited its fruits. This study aims to explore the removal of glucose, which are present in clinical waste by pineapple leaf biosorbents derived through three pre-treatment methods. Particle size analysis showed the smallest particle were from the steam pre-treated biosorbents and largest particles were from the 5% alkali pre-treated biosorbents. Fourier Transform Infrared Spectroscopy showed that lignin, hemicellulose, and cellulose remained unchanged in both the used and unused biosorbents. Despite the large particle size of the alkali pre-treated biosorbents, up to 70% of glucose was removed which might be due the improvement of the interfacial adhesion during the alkali treatment process

A Metabolic Activation Mechanism of 7H-Dibenzo[c,g]carbazole via O-Quinone. Part 2: Covalent Adducts of 7H-Dibenzo[c,g]carbazole-3,4-dione with Nucleic Acid Bases and Nucleosides

7H-Dibenzo[c,g]carbazole (DBC) is a potent multispecies, multisite carcinogen present in the environment. The metabolic activation pathways of DBC are not completely known. It is hypothesized that DBC may be metabolically activated by oxidation to the reactive Michael acceptor o-quinones, which can form stable and depurinating DNA adducts. The synthesis of DBC-3,4-dione has been previously reported by this research group. In the present article, we describe the synthesis and chemical structural elucidation of nine DBC-nucleic acid adducts produced from reactions of DBC-3,4-dione with Ade, Cyt, 2′-deoxyguanosine (dGuo), 2′- deoxycytidine (dCyd), and Guo. Adducts were isolated from reaction mixtures by HPLC and analyzed using MS including elemental compositions and collision-activated dissociation (CAD), 1H NMR, and two-dimensional chemical shift correlation spectroscopy (COSY) NMR. The adducts, 7-[3,4-dione-DBC-1-yl]-Ade, N4-[3,4-dione-DBC-1-yl]-Cyt, 5-[3,4-dione-DBC-1-yl]-Cyt, two conformational isomers of N2-[3,4-dihydroxy-DBC-1-yl]-dGuo, and two conformational isomers of N2-[3,4-dihydroxy-DBC-1-yl]-Guo, were characterized. Two adducts from reactions of DBC-3,4-dione with dCyd were identified by MS but not fully characterized by NMR due to instability of the adducts. Under similar conditions, the reactions of DBC-3,4-dione with Gua and 2′-deoxyadenosine (dAdo) did not result in an identifiable adduct. Liver DNA adducts from mice treated topically with DBC-3,4-dione (100 µg) in dimethyl sulfoxide/acetone (15/85, 100 µL) were identified with 32P-postlabeling. The major adduct chromatographically matched one of the adducts formed from livers of DBC-treated mouse (adduct 3) using identical conditions

Blood glucose response to a calamansi drink in healthy adults: a non‑randomised study

Objective: Glycaemic Index (GI) ranks the body’s response to carbohydrate content in food such that high GI food increases postprandial blood glucose levels. One of the popular drinks at food and beverage outlets is a drink made from calamansi, a citrus that is believed not to induce an increase in blood glucose levels. In this non-randomised single-blind (participants) study, capillary blood from 10 healthy males were sampled following consumption of either glucose or the calamansi drink. The blood glucose measurements were then used to calculate the GI for the drink. Results: The GI of the calamansi drink tested was calculated as 37, a value within the range of low GI foods. Trial registration Clinical Trials identifier NCT04462016; Retrospectively registered on July 1, 2020

Adaptation of in vitro cytoadherence assay to Plasmodium knowlesi field isolates

P. knowlesi was the first Plasmodium species in which antigenic variation was observed. Variation was due to schizont infected cell agglutination (SICAvar) antigens expressed by the parasite and transported to the exposed surface of the host erythrocyte [1]. PfEMP1 is P. falciparum’s orthologue of P. knowlesi’s SICA proteins [2]. In P. falciparum PfEMP1 is associated with infected erythrocytes binding to receptors such as ICAM-1 expressed on the endothelial cells of the host microvasculature. Here, we use a static protein assay [3] to determine if naturally occurring human P. knowlesi infections can cause erythrocytes to bind to ICAM-1, VCAM-1 and CD36

Absence of Plasmodium inui and Plasmodium cynomolgi, but detection of Plasmodium knowlesi and Plasmodium vivax infections in asymptomatic humans in the Betong division of Sarawak, Malaysian Borneo

Background: Plasmodium knowlesi, a simian malaria parasite, has become the main cause of malaria in Sarawak,Malaysian Borneo. Epidemiological data on malaria for Sarawak has been derived solely from hospitalized patients,and more accurate epidemiological data on malaria is necessary. Therefore, a longitudinal study of communities affected by knowlesi malaria was undertaken. Methods: A total of 3002 blood samples on filter paper were collected from 555 inhabitants of 8 longhouses with recently reported knowlesi malaria cases in the Betong Division of Sarawak, Malaysian Borneo. Each longhouse was visited bimonthly for a total of 10 times during a 21-month study period (Jan 2014–Oct 2015). DNA extracted from blood spots were examined by a nested PCR assay for Plasmodium and positive samples were then examined by nested PCR assays for Plasmodium falciparum, Plasmodium vivax, Plasmodium malariae, Plasmodium ovale, Plasmodium knowlesi, Plasmodium cynomolgi and Plasmodium inui. Blood films of samples positive by PCR were also examined by microscopy. Results: Genus-specific PCR assay detected Plasmodium DNA in 9 out of 3002 samples. Species-specific PCR identified 7 P. knowlesi and one P. vivax. Malaria parasites were observed in 5 thick blood films of the PCR positive samples. No parasites were observed in blood films from one knowlesi-, one vivax- and the genus-positive samples. Only one of 7 P. knowlesi-infected individual was febrile and had sought medical treatment at Betong Hospital the day after sampling. The 6 knowlesi-, one vivax- and one Plasmodium-infected individuals were afebrile and did not seek any medical treatment. Conclusions: Asymptomatic human P. knowlesi and P. vivax malaria infections, but not P. cynomolgi and P. inui infections,are occurring within communities affected with malaria

Cytoadherence and virulence - the case of Plasmodium knowlesi malaria

Background: Cytoadherence of infected red blood cells to brain endothelium is causally implicated in malarial coma, one of the severe manifestations of falciparum malaria. Cytoadherence is mediated by specific binding of variant parasite antigens, expressed on the surface of infected erythrocytes, to endothelial receptors including, ICAM-1, VCAM and CD36. In fatal cases of severe falciparum malaria with coma, blood vessels in the brain are characteristically congested with infected erythrocytes. Brain sections from a fatal case of knowlesi malaria, but without coma, were similarly congested with infected erythrocytes. The objective of this study was to determine the binding phenotype of Plasmodium knowlesi infected human erythrocytes to recombinant human ICAM-1, VCAM and CD36. Methods: Five patients with PCR-confirmed P. knowlesi malaria were recruited into the study with consent between April and August 2010. Pre-treatment venous blood was washed and cultured ex vivo to increase the proportion of schizont-infected erythrocytes. Cultured blood was seeded into Petri dishes with triplicate areas coated with ICAM-1, VCAM and CD36. Following incubation at 37°C for one hour the dishes were washed and the number of infected erythrocytes bound/mm2 to PBS control areas and to recombinant human ICAM-1 VCAM and CD36 coated areas were recorded. Each assay was performed in duplicate. Assay performance was monitored with the Plasmodium falciparum clone HB3. Results: Blood samples were cultured ex vivo for up to 14.5 h (mean 11.3 ± 1.9 h) to increase the relative proportion of mature trophozoite and schizont-infected red blood cells to at least 50% (mean 65.8 ± 17.51%). Three (60%) isolates bound significantly to ICAM-1 and VCAM, one (20%) isolate bound to VCAM and none of the five bound significantly to CD36. Conclusions: Plasmodium knowlesi infected erythrocytes from human subjects bind in a specific but variable manner to the inducible endothelial receptors ICAM-1 and VCAM. Binding to the constitutively-expressed endothelial receptor CD36 was not detected. Further work will be required to define the pathological consequences of these interactions

Susceptibility of human Plasmodium knowlesi infections to anti-malarials

Background: Evidence suggests that Plasmodium knowlesi malaria in Sarawak, Malaysian Borneo remains zoonotic, meaning anti-malarial drug resistance is unlikely to have developed in the absence of drug selection pressure. Therefore, adequate response to available anti-malarial treatments is assumed. Methods: Here the ex vivo sensitivity of human P. knowlesi isolates in Malaysian Borneo were studied, using a WHO schizont maturation assay modified to accommodate the quotidian life cycle of this parasite. The in vitro sensitivities of P. knowlesi H strain adapted from a primate infection to in vitro culture (by measuring the production of Plasmodium lactate dehydrogenase) were also examined together with some assays using Plasmodium falciparum and Plasmodium vivax. Results: Plasmodium knowlesi is uniformly highly sensitive to artemisinins, variably and moderately sensitive to chloroquine, and less sensitive to mefloquine. Conclusions: Taken together with reports of clinical failures when P. knowlesi is treated with mefloquine, the data suggest that caution is required if using mefloquine in prevention or treatment of P. knowlesi infections, until further studies are undertaken

Disease progression in Plasmodium knowlesi malaria is linked to variation in invasion gene family members.

Emerging pathogens undermine initiatives to control the global health impact of infectious diseases. Zoonotic malaria is no exception. Plasmodium knowlesi, a malaria parasite of Southeast Asian macaques, has entered the human population. P. knowlesi, like Plasmodium falciparum, can reach high parasitaemia in human infections, and the World Health Organization guidelines for severe malaria list hyperparasitaemia among the measures of severe malaria in both infections. Not all patients with P. knowlesi infections develop hyperparasitaemia, and it is important to determine why. Between isolate variability in erythrocyte invasion, efficiency seems key. Here we investigate the idea that particular alleles of two P. knowlesi erythrocyte invasion genes, P. knowlesi normocyte binding protein Pknbpxa and Pknbpxb, influence parasitaemia and human disease progression. Pknbpxa and Pknbpxb reference DNA sequences were generated from five geographically and temporally distinct P. knowlesi patient isolates. Polymorphic regions of each gene (approximately 800 bp) were identified by haplotyping 147 patient isolates at each locus. Parasitaemia in the study cohort was associated with markers of disease severity including liver and renal dysfunction, haemoglobin, platelets and lactate, (r = ≥ 0.34, p =  <0.0001 for all). Seventy-five and 51 Pknbpxa and Pknbpxb haplotypes were resolved in 138 (94%) and 134 (92%) patient isolates respectively. The haplotypes formed twelve Pknbpxa and two Pknbpxb allelic groups. Patients infected with parasites with particular Pknbpxa and Pknbpxb alleles within the groups had significantly higher parasitaemia and other markers of disease severity. Our study strongly suggests that P. knowlesi invasion gene variants contribute to parasite virulence. We focused on two invasion genes, and we anticipate that additional virulent loci will be identified in pathogen genome-wide studies. The multiple sustained entries of this diverse pathogen into the human population must give cause for concern to malaria elimination strategists in the Southeast Asian region

Lansium Domesticum: In Vitro Antimalarial Bioactivity And Its Effect On Plasmodium Falciparum Gene Expression

Reduced efficacies of current antimalarials meant that increasing the options for malaria chemotherapeutics continue to be an important part in global malaria control efforts. Lansium domesticum, a tree cultivated for its fruits, can be found ranging from China, Indochina to the Malay Archipelago. In Borneo, various parts of L. domesticum have been reported to be used by traditional healers for the treatment of malaria. The main objective of this study was to determine the mechanism of antiplasmodial activity of extracts prepared from the leaves of L. domesticum. The in vitro antiplasmodial activity of L. domesticum leaf extracts from two trees were extracted by two methods and assessed on two chloroquine-sensitive Plasmodium falciparum laboratory adapted clones 3D7 and HB3. This was done based on the parasite inhibition assay by the World Health Organisation. Leaves from Tree 1 were extracted using the organic solvent method, while leaves from Tree 2 were extracted using the organic solvent method and an ethno preparation based method. The organic solvent method resulted in the methanol extract and the dichloromethane (DCM) fraction; whereas the ethnopreparation-based methods resulted in the aqueous extracts. The methanol extracts derived from both trees in this study were active against P. falciparum clone 3D7 (IC50 of 84 μg/ml for Tree 1 and 28 μg/ml for Tree 2) and against P. falciparum clone HB3 (IC50 of 16 μg/ml for Tree 2). However, the malaria-active compounds appeared to partition into the DCM fraction (IC50 of 26 μg/ml for Tree 1 and 24 μg/ml for Tree 2). For the aqueous extracts, the hot and boiling water extracts were active against P. falciparum clone 3D7, whereas the cold water extract was active against P. falciparum clone HB3. However, the aqueous extracts were less potent compared to the organic solvent extracted samples.Therefore, the DCM fraction of L. domesticum leaf extracts was selected for studying the mechanism of activity on P. falciparum intraerythrocytic maturation. Gene expression profiles of P. falciparum clone 3D7 cultured in 10 μg/ml and 100 μg/ml of the DCM fraction over 4- or 12- hour period with non-treated cultures was compared using the GeneChipÒ Plasmodium/Anopheles genome array (AffymetrixÔ) and analysed using GeneSpringÒ (Agilent). Preliminary analysis using the one-on-one approach, comparing non-treated with treated parasites for a 4- or 12-hour period, was inconclusive. A multivariate analysis by Dr. Ken Laing showed that 12-hour exposure to the 100 μg/ml DCM fraction of L. domesticum was significantly different from non-treated cultures. Functional characterisation of this output using the Database for Annotation, Visualisation and Integrated Discovery (D.A.V.I.D.) suggests that 12-hour exposure to the 100 μg/ml DCM fraction of L. domesticum appears to target genes associated with the mitochondrion. Although this could be a reflection of a general downstream response to treatment rather than the specific mode of action of L. domesticum activity, identification of down-regulated genes that included oxidative phosphorylation, citrate cycle (TCA cycle), folate biosynthesis, purine/pyrimidine metabolism, nitrogen metabolism, fatty acid metabolism and ubiquitin-mediated proteolysis, supports the mitochondrion as the possible target. On the other hand, up-regulation of genes for ribosome, spliceosome, oxidative phosphorylation, fatty acid metabolism, purine metabolism, pentose phosphate pathway, fructose and mannose metabolism may be a reflection of secondary downstream compensation for the inhibitory effects of the DCM fraction of L. domesticum. Therefore, the DCM fraction of L. domesticum needs to be further assessed and studied as a potential addition to the antiplasmodial drug arsenal to help in the fight against malaria