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1.
Materials (Basel) ; 16(3)2023 Jan 29.
Article in English | MEDLINE | ID: mdl-36770152

ABSTRACT

This paper presents an experimental analysis of the optimization of PZT-based tiles for energy harvesting. The hardware (actual experiment), PZT-based tiles, were developed using 6 × 6 piezoelectric (PZT-lead zirconate titanate) sensors of 40 mm in diameter on a hard cardboard sheet (300 × 300 mm2). Our experimental analysis of the designed tiles obtained an optimized power of 3.626 mW (85 kg or 0.83 kN using 36 sensors) for one footstep and 0.9 mW for 30 footsteps at high tapping frequency. Theoretical analysis was conducted with software (Design-Expert) using the response surface methodology (RSM) for optimized PZT tiles, obtaining a power of 6784.155 mW at 150 kg or 1.47 kN weight using 34 sensors. This software helped to formulate the mathematical equation for the most suitable PZT tile model for power optimization. It used the quadratic model to provide adjusted and predicted R2 values of 0.9916 and 0.9650, respectively. The values were less than 0.2 apart, which indicates a high correlation between the actual and predicted values. The outcome of the various experiments can help with the selection of input factors for optimized power during pavement design.

2.
J Nepal Health Res Counc ; 15(1): 31-37, 2017 Jan.
Article in English | MEDLINE | ID: mdl-28714489

ABSTRACT

BACKGROUND: Adverse drug reactions (ADRs) can be a big threat to the health of people in Nepal as a variety of medicines are consumed in the country. Involving consumers in pharmacovigilance can strengthen ADR reporting. The study aims to find out knowledge, attitude and practice regarding pharmacovigilance and consumer pharmacovigilance among consumers at Lalitpur district, Nepal Methods: It was carried out in outpatients visiting in KIST Medical College and Teaching Hospital, Lalitpur, Nepal. Participant's knowledge, attitude and practice were measured by noting their agreement with a set of 21 statements along with multiple choice and open ended questions. RESULTS: A total of 157 outpatients were surveyed. The knowledge scores for males (12) was better compared to the females (11), but the scores for attitude and practice were same for both groups. The maximum score for knowledge was 29, attitude was 6 and practice was 10. The overall KAP scores was 45. The total scores for knowledge, attitude and practice for males (24) were better compared to female (22) respondents. Seventy-one patients (68%) who participated in this study favoured establishing a consumer centre for obtaining information about ADRs. CONCLUSIONS: Knowledge scores among consumers regarding pharmacovigilance is low and require advocacy and improvement.


Subject(s)
Health Knowledge, Attitudes, Practice , Pharmacovigilance , Adolescent , Adult , Child , Cross-Sectional Studies , Drug-Related Side Effects and Adverse Reactions/epidemiology , Female , Hospitals, Teaching , Humans , Male , Middle Aged , Nepal , Patient Education as Topic , Socioeconomic Factors , Young Adult
4.
J Neonatal Surg ; 3(2): 22, 2014.
Article in English | MEDLINE | ID: mdl-26023493

ABSTRACT

We report a case of full term female child having persistent cloaca who was diagnosed to have right lung agenesis on investigations.

5.
Pak J Biol Sci ; 16(20): 1223-5, 2013 Oct 15.
Article in English | MEDLINE | ID: mdl-24506029

ABSTRACT

In that study, Mimosa pudica linn was tested for diuretic activity using the lipschitz test. The ethanolic and aqoues extract of Mimosa pudica Linn. was studied at two dose level 100 and 200 mg kg(-1) b.wt. Furosemide (20 mg kg(-1) b.wt.) was used as standard drug in a 0.9% saline solution. Urine volumes were measured for all the groups up to 5 h. The ethanolic extract of Mimosa pudica linn was exhibited significant diuretic activity at doses of 100 and 200 mg kg(-1) b.wt. by increasing total urine volume and ion concentration of Na+ k+ and Cl-.


Subject(s)
Diuretics/chemistry , Diuretics/pharmacology , Mimosa/chemistry , Plant Extracts/chemistry , Plant Extracts/pharmacology , Animals , Ions/metabolism , Rats
6.
Talanta ; 77(1): 9-20, 2008 Oct 19.
Article in English | MEDLINE | ID: mdl-18804592

ABSTRACT

An overview of the advances in technologies, which can be used in the field as well as in a laboratory for the measurement of uranium in diverse matrices like, waters, minerals, mineralized rocks, and other beneficiation products for its exploration and processing industries is presented. Laser based technologies, ion chromatography, microsample X-ray analysis method followed by energy dispersive X-ray fluorescence technique (MXA-EDXRF), sensors for electrochemical detection followed by cyclic voltammogram and alpha liquid scintillation counting techniques are the most promising techniques. Among these techniques, laser fluorimetry/spectrofluorimetry, in particular, is the technique of choice because of its high performance qualification (PQ), inherent sensitivity, simplicity, cost effectiveness, minimum generation of analytical waste, rapidity, easy calibration and operation. It also fulfills the basic essential requirements of reliability, applicability and practicability (RAPs) for the analysis of uranium in solution of diverse matrices in entire nuclear fuel cycle. A very extensive range of uranium concentrations may be covered. Laser fluorimetry is suitable for direct determination of uranium in natural water systems within the microg L(-1) and mg L(-1) range while differential technique in laser fluorimetry (DT-LIF) is suitable for mineralized rocks and concentrates independent of matrix effects (uranium in samples containing >0.01% uranium). The most interesting feature of TRLIF is its capability of performing speciation of complexes directly in solution as well as remote determination via fiber optics and optrode. Future trend and advances in lasers, miniaturization and automation via flow injection analysis (FIA) has been discussed.


Subject(s)
Chemistry Techniques, Analytical/methods , Uranium/analysis , Chemistry Techniques, Analytical/instrumentation , Chromatography, Liquid , Lasers , Scintillation Counting , X-Rays
7.
Parasite Immunol ; 30(6-7): 371-4, 2008.
Article in English | MEDLINE | ID: mdl-18422872

ABSTRACT

Calreticulin (CalR), a Ca(2+) binding multifunctional protein, is secreted by the parasitic nematode Haemonchus contortus. We have earlier observed binding of this protein to a 24-kDa polypeptide (p24) present in an enriched preparation of prothrombin. In the present study, the identity of p24 was established as a C-reactive protein (CRP) by several criteria. CalR binding to CRP is an elegant strategy devised by the parasite to survive in the host. The secreted CalR may achieve this either by limiting the free concentration of CRP, which has antiparasite activity or inhibit the activation of the classical complement pathway triggered on binding of CRP to C1q protein. CalR binding to CRP would also ensure a check on the procoagulant activity of the CRP enabling parasite to feed on the host blood. Thus, targeting CalR could be a novel strategy to tackle this parasite, which has developed resistance to many anthelmintics.


Subject(s)
C-Reactive Protein/metabolism , Calreticulin/metabolism , Haemonchiasis/immunology , Haemonchiasis/metabolism , Haemonchus/physiology , Helminth Proteins/metabolism , Amino Acid Sequence , Animals , C-Reactive Protein/genetics , C-Reactive Protein/isolation & purification , Calreticulin/immunology , Complement Activation , Complement C1q/metabolism , Goats/blood , Goats/immunology , Molecular Sequence Data
8.
AJNR Am J Neuroradiol ; 27(8): 1712-6, 2006 Sep.
Article in English | MEDLINE | ID: mdl-16971620

ABSTRACT

BACKGROUND AND PURPOSE: Subacute sclerosing panencephalitis (SSPE), a rare progressive degenerative disease, is caused by persistent infection with a defective measles virus. The correlation between the clinical staging and MR imaging is usually poor. The aim of the study was to investigate the role of diffusion tensor imaging (DTI) in the early detection of white matter damage in SSPE in the presence of normal findings on conventional imaging. METHODS: DTI was performed in 21 patients in stage II SSPE and 10 age/sex-matched healthy controls. Fractional anisotropy (FA) and mean diffusivity (MD) values were calculated in the periventricular white matter, corpus callosum, and posterior limb of the internal capsule in patients with normal and abnormal findings on conventional imaging as well as healthy controls. RESULTS: The patients were grouped into those with normal (n = 11) and abnormal (n = 10) findings on conventional imaging for the purpose of quantitative DTI analysis. Abnormal- and normal-appearing white matter on T2-weighted images showed significantly decreased FA values in all the regions compared with those in healthy controls. MD values were significantly increased in the periventricular white matter region of the frontal and parietooccipital lobe in patients with normal as well as abnormal findings on conventional imaging compared with those in healthy controls. CONCLUSION: DTI detects early white matter abnormalities that may have significant therapeutic implication, even in the presence of normal findings on conventional imaging, in patients with SSPE.


Subject(s)
Brain Damage, Chronic/diagnosis , Cerebral Cortex/pathology , Diffusion Magnetic Resonance Imaging , Image Enhancement , Image Processing, Computer-Assisted , Internal Capsule/pathology , Subacute Sclerosing Panencephalitis/diagnosis , Adolescent , Atrophy , Child , Child, Preschool , Corpus Callosum/pathology , Female , Humans , Male , Neurologic Examination , Reference Values , Sensitivity and Specificity , Statistics as Topic , Thalamus/pathology
9.
Vet Parasitol ; 138(3-4): 291-300, 2006 Jun 15.
Article in English | MEDLINE | ID: mdl-16517075

ABSTRACT

A 66 kDa adult Haemonchus contortus excretory/secretory (E/S) antigen was identified in Western blot by reaction with sera from the infected goats. The protein was purified from the adult worm extract and E/S products by anion exchange and ConA-Sepharose chromatography. The purified protein inhibited monocyte function in vitro as judged by decreased production of hydrogen peroxide and nitric oxide in the culture medium. The protein also caused proliferation of peripheral blood mononuclear cells. The absence of protein in the free living L3 larvae suggests that the expression of this protein coincides with the adaptation to the parasitic life. A correlation of antibody titre and worm burden was observed in the infected goats with higher antibody levels in high worm burdened animals. Anti-protein antibody caused loss of adult worm motility in vitro resulting in the death of the parasite. The fact that the protein is recognized by the host together with in vitro killing of adult parasites by antibodies makes this protein a promising candidate for vaccination trial.


Subject(s)
Antigens, Helminth/immunology , Goat Diseases/parasitology , Haemonchiasis/veterinary , Haemonchus/immunology , Monocytes/immunology , Abomasum/parasitology , Animals , Antibodies, Helminth/biosynthesis , Antibodies, Helminth/blood , Antibodies, Helminth/metabolism , Antigens, Helminth/chemistry , Antigens, Helminth/isolation & purification , Blotting, Western/veterinary , Enzyme-Linked Immunosorbent Assay/veterinary , Goat Diseases/immunology , Goats , Haemonchiasis/immunology , Haemonchiasis/parasitology , Haemonchus/physiology , Host-Parasite Interactions/immunology , Hydrogen Peroxide/analysis , Lymphocytes/immunology , Lymphocytes/physiology , Monocytes/physiology , Movement/drug effects , Nitric Oxide/analysis
10.
Talanta ; 62(2): 343-9, 2004 Feb 06.
Article in English | MEDLINE | ID: mdl-18969301

ABSTRACT

A novel instrumental technique for the direct, fast, accurate, and precise determination of uranium in concentrates and other U-rich materials (as well as to mineralized rocks) is presented. The proposed technique is an absolute methodology, based on the comparison of the fluorescence of the accurately known standard with a sample of similar but unknown concentration in the low operational range of the instrument (on same sample-dilution basis), by the use of H(3)PO(4)-NH(4)H(2)PO(4) as a fluorescence-enhancing reagent. The relative standard deviation of the proposed technique was 0.5-0.9% (n=9) at 18.1, 36.2, 61.2, and 99.6% U(3)O(8). The proposed technique is suitable for the determination of uranium in samples arising from exploration projects, ores from mining operations, mill process samples, uranium ore concentrates leading to fuel fabrication as well as samples from environmental monitoring containing up to 100% uranium. The results are in good agreement with those obtained by titrimetric, gravimetric, and TBP extraction-H(2)O(2) spectrophotometric methods. The precision of the technique is within the acceptable 'pure geochemistry' type of analysis (R.S.D. approximately 1.0%) and is comparable even those obtained with titrimetric and gravimetric assay. The proposed differential technique coupled with flow injection may open up new advancement in instrumentation leading to design and development of microchemielectronic devices for direct on-line determination, more compatible with the tools of computer age as also to help in handling of radioactive solutions in chemical laboratories in uranium processing industries.

11.
Mol Biochem Parasitol ; 118(1): 75-82, 2001 Nov.
Article in English | MEDLINE | ID: mdl-11704275

ABSTRACT

The circumsporozoite protein is a predominant surface antigen present on Plasmodium sporozoites. In Plasmodium falciparum circumsporozoite protein (PfCSP), two cysteine residues (396 and 401) are present adjacent to two overlapping cytotoxic T-lymphocyte epitopes of the protein and are involved in the formation of disulfide bridges. We investigated the role of these cysteines on the cellular and antibody responses towards the CS protein because disruption of disulfide linkages and the presence of cysteine residues in the flanking region of an epitope has been shown to significantly alter the immune responses to various proteins. Mice were immunized with variant forms of PfCSP DNA vaccine plasmids where these cysteine residues were individually mutated to alanine. The plasmid vaccines induced antigen specific antibody and cytotoxic T lymphocyte responses. While no alterations of cysteine influenced the CTL responses to P. falciparum CS protein, vaccine pVRCS4, containing an altered cysteine at position 401, dramatically improved the antibody response to the carboxyl-terminal region of the protein. This work indicates that sequence alterations of genes in an anti-malarial vaccine could enhance the response towards the native protein. Given the fact that long term natural immunity to the pathogen has not been documented, it may be important to challenge the immune system with non-native proteins.


Subject(s)
Antibodies, Protozoan/blood , Disulfides/chemistry , Malaria Vaccines/immunology , Plasmodium falciparum/immunology , Protozoan Proteins/immunology , T-Lymphocytes, Cytotoxic/immunology , Amino Acid Sequence , Animals , Female , Malaria Vaccines/administration & dosage , Malaria, Falciparum/immunology , Malaria, Falciparum/prevention & control , Mice , Molecular Sequence Data , Plasmodium falciparum/genetics , Protozoan Proteins/chemistry , Protozoan Proteins/genetics , Vaccination , Vaccines, DNA/administration & dosage , Vaccines, DNA/immunology
12.
Biochemistry ; 40(38): 11518-24, 2001 Sep 25.
Article in English | MEDLINE | ID: mdl-11560500

ABSTRACT

Circumsporozoite (CS) protein is a predominant surface antigen of malaria sporozoites, the infective form of the parasite, and has been used for making anti-malaria vaccines. For the first time we have examined the interaction of CS protein with various glycosaminoglycans in real time using surface plasmon resonance (SPR) and isothermal titration calorimetry (ITC). Heparin was the best binder among the glycosaminoglycans tested and bound to CS protein with nanomolar affinity. Using purified and structurally defined small heparin oligosaccharides, we identified a decasaccharide to be the minimum sized CS protein-binding sequence. In an indirect competition assay, this decasaccharide blocked the CS protein interaction with HepG2 cells with an ID(50) of less than 60 nM. The decasaccharide has a structure commonly found in hepatic heparan sulfate, and the same sequence has recently been shown to bind specifically to apolipoprotein E. Examination of porcine liver heparan sulfate in this indirect competition assay showed that it and heparin were the only glycosaminoglycans that could effectively block CS protein interaction with HepG2 cells in culture. These data support the hypothesis that the invasion of liver cells by the parasite shares a common mechanism with the hepatic uptake of lipoprotein remnants from the blood.


Subject(s)
Glycosaminoglycans/chemistry , Heparin/chemistry , Oligosaccharides/chemistry , Protozoan Proteins/chemistry , Animals , Carbohydrate Conformation , Carbohydrate Sequence , Disaccharides/chemistry , Glycosaminoglycans/metabolism , Heparin/metabolism , Oligosaccharides/metabolism , Plasmodium , Protozoan Proteins/metabolism , Recombinant Proteins/chemistry , Recombinant Proteins/metabolism , Swine
13.
Fresenius J Anal Chem ; 370(4): 377-82, 2001 Jun.
Article in English | MEDLINE | ID: mdl-11495059

ABSTRACT

Amberlite XAD-2 has been functionalized by coupling it to quinalizarin [1,2,5,8-tetrahydroxyanthraquinone] by means of an -N = N- spacer. Elemental analysis, thermogravimetric analysis, and infrared spectra were used to characterize the resulting new polymer matrix. The matrix has been used to preconcentrate Cu(II), Cd(II), Co(II), Pb(II), Zn(II), and Mn(II) before their determination by flame atomic absorption spectrometry (FAAS). UO2(II) has been preconcentrated for fluorimetric determination. The optimum pH values for maximum adsorption of the metals are between 5.0 and 7.0. All these metal ions are desorbed (recovery 91-99%) with 4 mol L(-1) HNO3. The adsorptive capacity of the resin was found to be in the range 0.94-5.28 mg metal g(-1) resin and loading half-life (t1/2) between 5.3 and 15.0 min. The effects of NaF, NaCl, NaNO3, Na2SO4, Na3PO4, Ca(II), and Mg(II) on the adsorption of these metal ions (0.2 microg mL(-1)) are reported. The lower limits of detection for these metal ions are between 1 and 15.0 microg L(-1). After enrichment on this matrix flame AAS has been used to determine these metal ions (except the uranyl ion) in river water samples (RSD < or = 6.5%); fluorimetry was used to determine uranyl ion in well water samples (RSD < or = 6.3%). Cobalt from pharmaceutical vitamin tablets was preconcentrated by use of this chelating resin and estimated by FAAS (RSD approximately 4%).

14.
Comp Biochem Physiol C Toxicol Pharmacol ; 129(2): 93-104, 2001 Jun.
Article in English | MEDLINE | ID: mdl-11423382

ABSTRACT

Uric acid has been hypothesized as being one of the more important antioxidants in limiting the accumulation of glycosylated endproducts in birds. Study 1 was designed to quantitatively manipulate the plasma concentrations of uric acid using hemin and allopurinol while study 2 determined their effects on skin pentosidine, the shear force value of Pectoralis major muscle, plasma glucose, body weight and chemiluminescence monitored oxidative stress in broiler chickens. Hemin was hypothesized to raise uric acid concentrations thereby lowering oxidative stress whereas allopurinol was hypothesized to lower uric acid concentrations and raise measures of oxidative stress. In study 1 feeding allopurinol (10 mg/kg body weight) to 8-week-old broiler chicks (n=50) for 10 days decreased plasma uric acid by 57%. However, hemin (10 mg/kg body weight) increased uric acid concentrations 20%. In study 2, 12-week-old broiler chicks (n=90) were randomly assigned to either an ad libitum (AL) diet or a diet restricted (DR) group. Each group was further divided into three treatments (control, allopurinol or hemin fed). Unexpectedly, hemin did not significantly effect uric acid concentrations but increased (P<0.05) measures of chemiluminescence dependent oxidative stress in both the DR and AL birds probably due to the ability of iron to generate oxygen radicals. Allopurinol lowered concentrations of uric acid and increased (P<0.05) the oxidative stress in the AL birds at week 22, reduced (P<0.05) body weight in both the AL and DR fed birds at 16 and 22 weeks of age, and markedly increased (P<0.001) shear force values of the pectoralis major muscle. Skin pentosidine levels increased (P<0.05) in AL birds fed allopurinol or hemin fed birds, but not in the diet restricted birds at 22 weeks. The significance of these studies is that concentrations of plasma uric acid can be related to measures of oxidative stress, which can be linked to tissue aging.


Subject(s)
Aging/metabolism , Allopurinol/pharmacology , Arginine/analogs & derivatives , Arginine/pharmacology , Chickens/metabolism , Glycation End Products, Advanced/metabolism , Hemin/pharmacology , Lysine/analogs & derivatives , Lysine/pharmacology , Oxidative Stress , Uric Acid/metabolism , Allopurinol/administration & dosage , Animals , Antimetabolites/pharmacology , Blood Glucose/analysis , Blood Glucose/drug effects , Body Weight/drug effects , Chickens/blood , Cross-Linking Reagents/pharmacology , Diet , Glycosylation , Hemin/administration & dosage , Luminescent Measurements , Muscle, Skeletal/drug effects , Skin/metabolism , Uric Acid/blood
15.
J Infect Dis ; 183(11): 1653-61, 2001 Jun 01.
Article in English | MEDLINE | ID: mdl-11343215

ABSTRACT

Chloroquine (CQ)-resistant Plasmodium vivax malaria was first reported 12 years ago, nearly 30 years after the recognition of CQ-resistant P. falciparum. Loss of CQ efficacy now poses a severe problem for the prevention and treatment of both diseases. Mutations in a digestive vacuole protein encoded by a 13-exon gene, pfcrt, were shown recently to have a central role in the CQ resistance (CQR) of P. falciparum. Whether mutations in pfcrt orthologues of other Plasmodium species are involved in CQR remains an open question. This report describes pfcrt homologues from P. vivax, P. knowlesi, P. berghei, and Dictyostelium discoideum. Synteny between the P. falciparum and P. vivax genes is demonstrated. However, a survey of patient isolates and monkey-adapted lines has shown no association between in vivo CQR and codon mutations in the P. vivax gene. This is evidence that the molecular events underlying P. vivax CQR differ from those in P. falciparum.


Subject(s)
Chloroquine/pharmacology , Molecular Chaperones/genetics , Plasmodium/drug effects , Amino Acid Sequence , Animals , Codon , Dictyostelium/chemistry , Dictyostelium/genetics , Drug Resistance , Humans , Molecular Sequence Data , Mutation , Parasitic Sensitivity Tests , Plasmodium/chemistry , Plasmodium/genetics , Sequence Alignment
16.
Eur Psychiatry ; 16(3): 186-90, 2001 Apr.
Article in English | MEDLINE | ID: mdl-11353598

ABSTRACT

Topiramate is an antiepileptic agent, which is being investigated as a mood-stabilizer. Three obese individuals with DSM-IV bipolar I disorder and type II diabetes mellitus received topiramate treatment in combination with antipsychotics and valproate or carbamazepine. In addition to improved mood stability, these individuals lost between 16 to 20.5% of their pre-topiramate body weight and also achieved significant glycemic control.


Subject(s)
Anticonvulsants/therapeutic use , Bipolar Disorder/drug therapy , Fructose/therapeutic use , Hyperglycemia/drug therapy , Weight Loss , Adult , Anticonvulsants/administration & dosage , Bipolar Disorder/complications , Bipolar Disorder/diagnosis , Body Mass Index , Diabetes Mellitus, Type 2/complications , Diabetes Mellitus, Type 2/epidemiology , Female , Fructose/administration & dosage , Fructose/analogs & derivatives , Humans , Hyperglycemia/complications , Hyperglycemia/epidemiology , Male , Middle Aged , Obesity/complications , Obesity/drug therapy , Time , Topiramate
17.
Mol Biochem Parasitol ; 114(1): 89-94, 2001 Apr 25.
Article in English | MEDLINE | ID: mdl-11356517

ABSTRACT

Gene trees of Plasmodium species have been reported for the nuclear encoded genes (e.g. the Small Subunit rRNA) and a mitochondrial encoded gene, cytochrome b. Here, we have analyzed a plastid gene coding for caseinolytic protease ClpC, whose structure, function and evolutionary history have been studied in various organisms. This protein possesses a 220-250 amino acid long AAA domain (ATPases associated with a variety of cellular activities) that belongs to the Walker super family of ATPases and GTPases. We have sequenced the AAA motif of this gene, encoding the protein from nine different species of Plasmodium infecting rodents, birds, monkeys, and humans. The codon usage and GC content of each gene were nearly identical in contrast to the widely varying nucleotide composition of genomic DNAs. Phylogenetic trees derived from both DNA and inferred protein sequences have consistent topologies. We have used the ClpC sequence to analyze the phylogenetic relationship among Plasmodium species and compared it with those derived from mitochondrial and genomic sequences. The results corroborate well with the trees constructed using the mitochondrially encoded cytochrome b. However, an important element distinguishes the trees: the placement of Plasmodium elongatum near the base of the plastid tree, indicating an ancient lineage of parasites in birds that branches from the tree prior to other lineages of avian malaria and the human parasite, P. falciparum.


Subject(s)
Cytochrome b Group/genetics , DNA, Mitochondrial/genetics , DNA, Protozoan/genetics , Evolution, Molecular , Phylogeny , Plasmodium/classification , Plasmodium/genetics , Adenosine Triphosphatases/chemistry , Amino Acid Sequence , Animals , Birds , Cell Nucleus/genetics , DNA, Mitochondrial/chemistry , DNA, Protozoan/chemistry , DNA, Ribosomal/genetics , Genes, Protozoan , Haplorhini , Humans , Mitochondria/genetics , Molecular Sequence Data , Peptide Hydrolases/chemistry , Peptide Hydrolases/genetics , Plastids/genetics , Rodentia , Sequence Alignment , Sequence Homology, Amino Acid
18.
Emerg Infect Dis ; 7(1): 35-42, 2001.
Article in English | MEDLINE | ID: mdl-11266292

ABSTRACT

We examined geographically distinct isolates of Plasmodium vivax and categorized them according to developmental success in Anopheles albimanus. We found that parasites from Central America and Colombia form a group distinct from those of Asia. New World isolates have a distinct chromosomal translocation and an episomal variation in the open reading frame (ORF) 470 DNA sequence that distinguishes them from the other isolates tested. Old World types of P. vivax were introduced into the Americas, and a remnant of this lineage remains in P. simium. It is indistinguishable from Old World P. vivax to the extent determinable by using our encoded markers and the examination of its developmental pattern in mosquitoes. The cohesive characteristics that separate types of P. vivax are predictors of range and potential for transmission and hence require taxonomic distinction.


Subject(s)
Plasmodium vivax/classification , Amino Acid Sequence , Animals , Anopheles/parasitology , Base Sequence , Genetic Markers , Molecular Sequence Data , Open Reading Frames , Plasmodium vivax/genetics , Plasmodium vivax/isolation & purification , RNA, Ribosomal/genetics
19.
Proc Natl Acad Sci U S A ; 97(15): 8530-5, 2000 Jul 18.
Article in English | MEDLINE | ID: mdl-10890903

ABSTRACT

Various pathogenic bacteria, viruses, and protozoan bind to glycosaminoglycan-based receptors on host cells and initiate an infection. Sporozoites of Plasmodium predominantly express circumsporozoite (CS) protein on their surface, which binds to heparan sulfate proteoglycans on liver cell surface that subsequently leads to malaria. Here we show that the interaction of free heparin with this parasite ligand has the potential to be a critical component of invasion. CS protein of P. falciparum contains four cysteines at positions 361, 365, 396, and 401. In this study, all four cysteine residues were mutagenized to alanine both individually and in different combinations. Conversion of cysteine 396 to alanine (protein CS3) led to a 10-fold increase in the binding activity of the protein to HepG2 cells. Replacement of cysteines at positions 361, 365, and 401 either alone or in different combinations led to a near total loss of binding. Surprisingly, activity in these inactive mutants could be effectively restored in the presence of submolar concentrations of heparin. Heparin also up-regulated binding of CS3 at submolar concentrations with respect to the protein but down-regulated binding when present in excess. Given the significantly different concentrations of heparin in different organs of the host and the in vitro results described here one can consider in vivo ramifications of this phenomenon for pathogen targeting of specific organs and for the functional effects of antigenic variation on receptor ligand interaction.


Subject(s)
Cysteine/physiology , Heparin/metabolism , Plasmodium falciparum , Protozoan Proteins/physiology , Amino Acid Sequence , Amino Acid Substitution , Animals , Binding, Competitive , Cysteine/genetics , Cysteine/metabolism , Gene Expression , Heparin Lyase/metabolism , Humans , Molecular Sequence Data , Mutagenesis, Site-Directed , Peptides/metabolism , Protozoan Proteins/genetics , Protozoan Proteins/isolation & purification , Protozoan Proteins/metabolism , Tumor Cells, Cultured
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