Modified plastic optical fiber with CNT and graphene oxide nanostructured coatings for ethanol liquid sensing.

A high sensitivity and simple ethanol sensor based on an un-cladded multimode plastic optical fiber (UCPOF) coated with carbon nanotubes (CNTs) for the detection of different concentrations of ethanol in de-ionized water is developed and demonstrated. The UCPOF probe is fabricated by chemically removing the fiber cladding and integrated with CNT as a sensing layer. The effect of surface morphology on the sensor performance is investigated by characterizing another UCPOF coated with GO nanomaterial. The developed fibers are coated with CNTs and GO using drop casting technique. Energy dispersive X-ray spectroscopy (EDX), atomic-force microscopy (AFM) and scanning electron microscope (SEM) are used to investigate the element and morphology of the synthesized nanomaterials. The experimental results indicated that the absorbance spectrum of the CNT-based UCPOF sensor increases linearly with a higher sensitivity of 0.68/vol% and magnitude change of 95.4% as compared to 0.19/vol% and 56.3%, respectively, for the GO-based sensor. The UCPOF coated with CNT exhibits faster response and recovery than that of GO. The sensor shows high selectivity to ethanol amongst a range of diluted organic VOCs. The superior sensing performance of the developed fiber sensor indicates its high efficiency for ethanol detection in various industrial applications.

Evaluation of anti convulsant activity of aerial parts of Phyllanthus longiflorus heyne ex hook.

OBJECTIVE: To evaluate anti convulsant effect of aerial parts of Phyllanthus longiflorus (PHL). MATERIALS AND METHOD: Methanol extract of aerial parts of PHL (MPHL) was prepared by continuous hot extraction method using Soxhlet apparatus. MPHL at the doses 100, 200 and 400 mg/kg were administered to male albino mice by oral route and the activity was assessed against maximal electro shock (MES) and pentylene tetrazole (PTZ) induced seizure. Abolition of hind limb extension and onset of clonic convulsion were taken as a measure of MES and PTZ induced convulsion respectively. RESULTS: MPHL reduced the duration of extensor phase of convulsion in MES test by 62.5% (at 400 mg/kg) and also delayed the onset of clonic phase of convulsion in PTZ test by 50.7% (at 400 mg/kg). The activity was significant (p < 0.01) and comparable to the reference drug diazepam (2 mg/kg). CONCLUSION: Results suggest that aerial parts of Phyllanthus longiflorus are useful in the management of convulsion.

In vitro reactivation of Ancylostoma caninum tissue-arrested third-stage larvae by transforming growth factor-beta.

Developmental arrest in Ancylostoma caninum is associated with preparasitic, free-living third-stage (L3) larvae, as well as anthelmintic-resilient hypobiotic L3 larvae within the tissues of an infected dog. With the tissue-arrested larvae, pregnancy and, more specifically, the hormonal effects of estrogen and prolactin mediate reactivation resulting in transmammary transmission of infection to nursing puppies. Estrogen and prolactin have been shown to be critically involved in upregulation of transforming growth factor (TGF)-beta2 during pregnancy, and studies on the soil nematode Caenorhabditis elegans further implicate TGF-beta and insulin-like signaling pathways with larval arrest and reactivation. In this report, an in vitro assay was used to show that neither estrogen, prolactin, nor insulin had a direct effect on the feeding/reactivation response of tissue-arrested larvae; however, TGF-beta isoforms 1 and 2 both had significant stimulatory effects that were comparable to the effects of dog serum. The stimulatory effects of serum could be blocked by preincubation with anti-TGF-beta antibodies. Taken together, the results support the hypothesis that during pregnancy, host-derived TGF-beta can signal a parasite-encoded receptor to trigger the reactivation of tissue-arrested larvae. TGF-beta had no effect on preparasitic larvae, suggesting that different signals may be involved in reactivation of the 2 different arrested forms of A. caninum L3 larvae.

Developmental arrest and pregnancy-induced transmammary transmission of Ancylostoma caninum larvae in the murine model.

Pregnancy is associated with reactivation of latent infections of many protozoal and helminthic parasites. To facilitate in vivo studies on the process of transmammary transmission of hookworm infection to nursing newborns, we established an experimental model of infection of BALB/c mice with infective larvae of the canine nematode Ancylostoma caninum. To establish latency with a significant reservoir of tissue larvae and achieve acceptable pregnancy success rates, mice were subcutaneously infected at day 5 postimpregnation; similar larval distribution profiles were observed at the end of the gestational period for bred compared to correspondingly infected unbred animals. No larvae were detected in fetuses or neonatal pups. Significant numbers of larvae were not detected in mammary tissue during the periparturient or postpartum lactational periods although about 8% of a dam's reservoir of tissue larvae was transferred to her nursing pups; this suggests that larvae reaching the mammary glands are rapidly transmitted through the milk sinuses, as was documented by histopathological analyses. Comparison of BALB/c with C57BL/6 mice that typically display divergent immune responses to infection showed no difference in tissue larval burden or in numbers transferred to pups. A hypothesis for the molecular mechanism of larval reactivation and transmission is discussed.

Antibody responses in pregnancy-induced transmammary transmission of Ancylostoma caninum hookworm larvae.

Third stage larvae of the Ancylostoma caninum hookworm nematode have the capacity to infect a dog, abort the normal maturation pathway to become blood-feeding intestinal worms, and instead distribute throughout the body in a developmentally arrested state that is relatively resilient to most chemotherapeutic agents. During pregnancy, a percentage of the arrested larvae reactivate and transmit via the mammary glands to infect the nursing puppies with resulting iron-deficiency anemia and potential mortality. To determine if the suppression of parasite-specific antibody responses during pregnancy facilitates the reactivation and transmammary transfer of hookworm larvae, a murine model of A. caninum infection was used to compare the infected versus uninfected animals that were either bred or not bred. Initial comparisons of genetically divergent BALB/c versus C57BL/6 mice showed that both the strains mounted strong Th2 biased IgG1 and IgE antibody responses to A. caninum infection. Using the BALB/c strain for the breeding analyses, it was confirmed that larval transfer to the mouse pups only occurred during the post-partum lactational period. In the dams, levels of total and antigen-specific IgG1 and total IgE were highly correlated with parasite burden. During most phases of pregnancy and lactation, infected dams had lower total IgG1, IgG2a and IgE levels as compared to unbred mice at comparable times post-infection; this downward modulation of antibody responses supports the established dogma of a generalized immunosuppression associated with pregnancy. However, at parturition and post-partum lactation, antigen-specific IgG1 levels measured at 1:5000 serum dilutions were comparable between bred and unbred mice, and antigen-specific IgG2a levels at 1:100 serum dilutions were also not significantly different except for a marginal reduction in the bred mice at the lactational timepoint. The comparable anti-A. caninum IgG1 levels between bred and unbred mice, and low correlation between IgG2a levels and larval burden suggest that parasite-specific antibody responses do not play a major role in the pregnancy-associated transmammary transmission of A. caninum larvae. This conclusion does not rule out the possibility that underlying fluxes in the levels of specific cytokines associated with pregnancy and infection may be involved in the process of larval reactivation and transmission.

Anthelmintic efficacy against tissue-arrested larvae of Ancylostoma caninum in murine hosts.

Third-stage larvae of the major human and canine Ancylostoma hookworm species have the capacity to undergo developmental arrest in the somatic tissues of an infected host. Arrested larvae reactivate at opportune periods such as pregnancy, which results in the transmammary transmission of infection to the nursing neonates. Using murine paratenic hosts to focus specifically on tissue-arrested stages of Ancylostoma caninum, the present study found that neither recommended nor elevated doses of commonly used anthelmintics were effective in eliminating latent infections at the accepted standard of greater than 90% reduction in parasite burden. Of the drugs tested, i.e., pyrantel, fenbendazole, ivermectin, and milbemycin, ivermectin was the most effective and engendered an 80% reduction in the burden of tissue-arrested A. caninum larvae but only if administered repeatedly or at elevated doses. Studies in 2 inbred mouse strains, BALB/c (H-2b) and C57BL/6 (H-2d), that typically display divergent immune responses to various infections showed no significant differences in the efficacies of the drugs tested. The results of this study indicate that there is still a need for effective strategies of eradicating latent infections with tissue-arrested hookworm larvae.

Molecular analysis of antigens targeted by protective antibodies in rapid expulsion of Trichinella spiralis.

Rapid expulsion is a protective immune mechanism which eliminates as much as 99% of a challenge infection of Trichinella spiralis muscle larvae from the gastrointestinal tract of suckling rats. Protective monoclonal antibodies (mAbs) generated against larval excretory-secretory antigens (ESA) specifically recognize a 45-kDa glycoprotein, gp45, in addition to a distinct profile of other cross-reactive antigens that are also recognized by non-protective mAbs. Recent data indicate that protective mAbs recognize carbohydrate epitopes. To complement biochemical studies on the target(s) of rapid expulsion, we describe here the cloning and characterization of the cDNA, TspE1, which belongs to a multigene family and encodes several larval proteins in the 40-50-kDa range. A second cDNA, TspM6 encodes a 45-kDa antigen and is homologous to the published sequence of gp45. Anti-TspE1 antibodies detected antigens within beta- and gamma-stichocytes while anti-TspM6 antibodies detected antigens within alpha-stichocytes of the secretory organs of muscle larvae. Sequence analysis has provided no functional information on the encoded gene products. Neither recombinant antigen is recognized by the mAbs but native parasite molecules with peptide homology to both the TspE1 and TspM6 recombinant antigens bear the glycan recognized by the protective mAbs. These molecules are candidate targets in rapid expulsion.

Mixed ligand complexes involving sulphur containing ligands--Part II. Ternary complexes of Zn(II) involving L-cysteine/D-penicillamine/L-cysteic acid and imidazoles.

The chemical equilibria involved in nine mixed ligand systems Zn(II)-L-cysteine (Cys)/D-penicillamine(Pen)/L-cysteic acid(Cya)(A)-imidazole(Him), histamine(Hist) and L-histidine(His)(B) have been investigated in aqueous perchlorate medium by pH titrimetry at 37 degrees and ionic strength, I = 0.15M (NaClO(4)). The mixed ligand complex species of the types ZnABH(2), ZnABH, ZnAB or ZnAB(2) have been detected in addition to various binary species due to ligands A and B. The results obtained for the ZnABH type of species indicate that the site of protonation is the amino group of Cys/Pen ligands in the Zn(II)-Cys/Pen(A)-Him, Hist and His(B) systems, and the amino group of Hist/His secondary ligands in the Zn(II)-Cya(A)-Hist and His(B) systems. In the ZnABH(2) type of species, one proton is attached with the primary ligand (A) and the other with the secondary ligand(B). In both ZnAB and ZnAB(2) type ternary species in all the systems, the primary ligand binds the metal in a bidentate manner and the secondary ligands Him, Hist and His bind the metal, respectively in a uni, bi and terdentate manner.

Negative regulatory sequences in the lin-14 3'-untranslated region are necessary to generate a temporal switch during Caenorhabditis elegans development.

The heterchronic gene lin-14 controls the temporal sequence of developmental events in the Caenorhabditis elegans postembryonic cell lineage. It encodes a nuclear protein that normally is present in most somatic cells of late embryos and L1 larvae but is absent at later stages. Two lin-14 gain-of-function mutations delete 3'-untranslated sequences causing an inappropriately high level of the lin-14 nuclear protein late in development. These mutations identify a negative regulatory element that controls the formation of the lin-14 protein temporal gradient. The 21-kb lin-14 gene is differentially spliced to generate three lin-14 transcripts that encode protein products with variable amino-terminal regions and a constant carboxy-terminal region. The sequence of the gene revealed no protein sequence similarity to any proteins in various data bases.

Temporal regulation of lin-14 by the antagonistic action of two other heterochronic genes, lin-4 and lin-28.

Heterochronic genes form a regulatory pathway that controls the temporal sequence of the Caenorhabditis elegans postembryonic cell lineage. One of these genes, lin-14, encodes a nuclear protein that constitutes a temporal developmental switch. During wild-type development, lin-14 protein is abundant during early larval stage 1 (L1) to specific L1-specific cell lineages but is nearly undetectable at L2 and later stages to specify L2-specific and later cell lineages. To determine the roles played by other genes in executing this temporal switch, we have analyzed how lin-14 expression is regulated by other heterochronic genes. lin-4 is required to down-regulate lin-14 protein levels during the L1 stage, whereas lin-28 positively regulates lin-14 protein levels. The lin-4 gene product is a candidate for interacting with the negative regulatory element in the 3'-untranslated region of lin-14. lin-29 mutations do not affect lin-14 protein levels, consistent with lin-29 acting downstream of lin-14. Switching off lin-14 expression during the L1 stage is not triggered by the passage of time per se but, rather, is normally dependent on feeding or the feeding-dependent initiation of postembryonic cell division.

Dominant gain-of-function mutations that lead to misregulation of the C. elegans heterochronic gene lin-14, and the evolutionary implications of dominant mutations in pattern-formation genes.

The heterochronic gene lin-14 controls the temporal sequence of developmental events in the C. elegans postembryonic cell lineage. It encodes a nuclear protein that is normally present in most somatic cells of late embryos and L1 larvae but not in later larval stages or adults. Two lin-14 gain-of-function mutations cause an inappropriately high level of the lin-14 nuclear protein late in development. These mutations delete 3' untranslated sequences from the lin-14 mRNAs and identify a negative regulatory element that controls the formation of the lin-14 protein temporal gradient. The 21 kb lin-14 gene contains 13 exons that are differentially spliced to generate two lin-14 protein products with variable N-terminal regions and a constant C-terminal region. No protein sequence similarity to any proteins in various databases was found. The temporal and cellular expression patterns of lin-14 protein accumulation is altered by mutations in the heterochronic genes lin-4 and lin-28. The lin-4 gene is required to down-regulate lin-14 protein levels during the mid-L1 stage. The lin-4 gene product could be the trans-acting factor that binds to the negative regulatory element in the lin-14 3' untranslated region. In contrast, the lin-28 gene activity positively regulates lin-14 protein levels during early L1. Thus, these genes act antagonistically to regulate the lin-14 temporal switch. The normal down-regulation of lin-14 within 10 h of hatching is not determined by the passage of time per se, but rather is triggered when feeding induces post-embryonic development.(ABSTRACT TRUNCATED AT 250 WORDS)

Human T-cell stimulation, molecular characterization and in situ mRNA localization of a Brugia malayi recombinant antigen.

Cellular immune responses play a major role in lymphatic filarial infections. To further our understanding of the host-parasite interaction, we investigated T-cell stimulation by purified filarial recombinant antigens in peripheral blood mononuclear cells derived from filarial-infected individuals. One of a subset of cloned Brugia malayi antigens involved in the humoral immune response to filarial infection was found to be a T-cell-stimulating antigen. The fusion protein encoded by clone lambda Bm19 induced proliferation of human T cells in a parasite-specific, antigen dose-dependent manner. The deduced amino acid sequence from this cloned region revealed 4 predicted T-cell recognition sites. The lambda Bm19 DNA sequence hybridizes to a 3-kb transcript, and in situ mRNA hybridization analyses of the adult female worm demonstrated that this gene is expressed in developing uterine microfilariae. The native parasite protein is present in several developmental stages since clone lambda Bm19 was initially identified with antiserum directed against the infective larval stage; this protein is therefore a potential target for the host's immune system.

Molecular clones of alpha-tubulin genes of Plasmodium yoelii reveal an unusual feature of the carboxy terminus.

By using a Trypanosoma brucei alpha-tubulin cDNA probe under reduced stringency hybridization conditions, we have isolated two genomic clones that constitute portions of alpha-tubulin genes of the rodent malarial parasite Plasmodium yoelii. P. yoelii has two alpha-tubulin genes, the 3' portions of which were present in the two clones, Py alpha T1 and Py alpha T2, containing 1.3 kb and 6.6 kb EcoRI fragments respectively. The 1358 bp Py alpha T1 clone was completely sequenced and found to contain 591 nucleotides of uninterrupted coding sequence with a strong bias for AT-rich codons, starting with codon 254 of a consensus alpha-tubulin sequence. Numerous attempts to clone 5' portions of these genes were unsuccessful. A single mRNA of 2.3 kb was recognized by both the clones in the erythrocytic stages of P. yoelii. A probe constituting the untranslated sequences of Py alpha T1 also recognized this RNA but failed to hybridize with Py alpha T2 sequences, indicating that the gene represented by the Py alpha T1 clone was expressed during the erythrocytic stages. The deduced amino acid sequence of the Py alpha T1 gene terminates in Tyr-Glu instead of Glu-Tyr observed in alpha-tubulins of almost all other organisms. The difference observed may have implications for alpha-tubulin metabolism in malarial parasites.

Brugia malayi: recombinant antigens expressed by genomic DNA clones.

A Brugia malayi genomic DNA expression library was screened with rabbit antiserum generated against live infective larvae and 33 clones were identified. Five randomly selected clones were characterized in detail by Western blot, DNA and RNA analyses. The fusion proteins produced by each of these recombinant DNA clones are expressed by different genomic sequences. A profile of antigenic cross-reactivities of all 33 recombinant clones was compiled using a battery of antisera, including sera from humans infected with B. malayi. A high percentage of clones were cross-reactive with antisera against the filarial parasites B. pahangi, Dirofilaria immitis, and Onchocerca volvulus. We have made a preliminary identification of three categories of recombinant clones encoding (1) antigens that were cross-reactive with some or all antisera tested, (2) antigens that were specific to the Brugia genus, and (3) antigens that appeared to be specific to B. malayi. These recombinant antigens are candidates for further studies in filarial immunoprophylaxis and diagnosis.

Tandemly arranged gene clusters of malarial parasites that are highly conserved and transcribed.

A molecular clone containing a 5.8 kb Eco RI fragment was isolated from a genomic library of the rodent malarial parasite Plasmodium yoelii. The P. yoelii genome contains about 150 copies of this sequence, making up almost 3% of the DNA. These sequences are tandemly arrayed in head-to-tail configurations with the unit length of the repeat being 5.8 kb. Several poly(A+) RNAs of P. yoelii ranging from 1.6 to 0.3 kb are recognized by the 5.8 kb clone. Five additional species of malarial parasites (P. chabaudi, P. berghei, P. falciparum, P. knowlesi, and P. cynomolgi) contain tandemly repeated arrays of sequences having the same unit length of 5.8 kb, which readily hybridize to the sequence cloned from P. yoelii.