Effects of radiation and role of plants in radioprotection: A critical review

Radiation can be lethal at high doses, whereas controlled doses are useful in medical applications. Other applications include power generation, agriculture sterilization, nuclear weapons, and archeology. Radiation damages genetic material, which is reflected in genotoxicity and can cause hereditary damage. In the medical field, it is essential to avoid the harmful effects of radiation. Radiation countermeasures and the need for radioprotective agents have been explored in recent years. Considering plants that evolve in radiative conditions, their ability to protect organisms against radiation has been studied and demonstrated. Crude extracts, fractioned extracts, isolated phytocompounds, and plant polysaccharides from various plants have been used in radioprotection studies, and their efficiency has been proven in various in vitro and in vivo experimental models. It is important to identify the mechanism of action to develop a potent plant-based radioprotective agent. To identify this protective mechanism, it is necessary to understand the damage caused by radiation in biological systems. This review intends to discuss the effects of ionizing radiation on biological systems and evaluate plant-based radioprotectants that have tested thus far as well as their mechanism of action in protecting against the toxic effects of radiation. From the review, the mechanism of radioprotection exhibited by the plant-based products could be understood. Meanwhile, we strongly suggest that the potential products identified so far should undergo clinical trials for critically evaluating their effects and for developing an ideal and compatible radioprotectant with no side-effects.

Combined in vitro and in silico approach to evaluate the inhibitory potential of an underutilized allium vegetable and its pharmacologically active compounds on multidrug resistant Candida species

Candida infections and related mortality have become a challenge to global health. Nontoxic and natural bioactive compounds from plants are regarded as promising candidates to inhibit these multidrug resistant strains. In the present study, in vitro assays and in silico molecular docking approach was combined to evaluate the inhibitory effect of crude extracts from Allium ampeloprasum and its variety A. porrum on Candida pathogens. Phytochemical screening revealed the presence of phenolic acids and flavonoids in higher quantity. Spectral studies of the extracts support the presence of phenols, flavonoids and organosulfur compounds. Aqueous extract of A. ampeloprasum showed a total antioxidant capacity of 68 ± 1.7 mg AAE/ g and an IC50 value of 0.88 ± 2.1 mg/ml was obtained for DPPH radicals scavenging assay. C. albicans were highly susceptible (19.9 ± 1.1 mm) when treated with aqueous A. ampeloprasum extract. Minimum inhibitory concentrations were within the range of 19-40 μg/ml and the results were significant (p ≤ 0.05). In silico molecular docking studies demonstrated that bioactive phytocompounds of A. ampeloprasum and A. porrum efficiently interacted with the active site of Secreted aspartyl proteinase 2 enzyme that is responsible for the virulence of pathogenic yeasts. Rosmarinic acid and Myricetin exhibited low binding energies and higher number of hydrogen bond interactions with the protein target. Thus the study concludes that A. ampeloprasum and A. porrum that remain as underutilized vegetables in the Allium genus are potential anti-candida agents and their pharmacologically active compounds must be considered as competent candidates for drug discovery.

Spectral characterization of hydroxyapatite extracted from Black Sumatra and Fighting cock bone samples: A comparative analysis

At present, chicken business is occupying a major portion in the market and huge amount of bone wastes are dumped into the open places lead in environmental pollution. In this analysis, natural hydroxyapatite was extracted by thermal calcination process at different temperature ranges from 700 °C, 900 °C and 1100 °C and compared its spectral characteristics. The crystalline nature, functional groups and morphological characteristics of hydroxyapatite obtained from both bone samples were studied using XRD, FTIR and SEM analysis. The crystallite size, lattice parameters, specific surface area, volume and degree of crystallinity were measured using XRD data. The mean grain size of Black Sumatra and Fighting Cock bone hydroxyapatite was 62.67 nm and 31.34 nm respectively. The FTIR spectrum showed major peaks at 634.58 cm⁻¹ and 470.63 cm⁻¹, 1413.82 cm⁻¹ and 1460 cm⁻¹ indicates the presence of carbonate group and phosphate groups in both samples. The SEM micrograph confirmed the existence of maximum pores in matrix of fighting cock bone than Black Sumatra bone sample. Thus, the comparative analysis concluded that nano-sized hydroxyapetite obtained from bone wastes of fighting cock can be utilized as a low-cost biomaterial for the production of various implant coating materials and substitute for ceramics in bones and dentistry applications.

Metagenomics for taxonomy profiling: tools and approaches

The study of metagenomics is an emerging field that identifies the total genetic materials in an organism along with the set of all genetic materials like deoxyribonucleic acid and ribose nucleic acid, which play a key role with the maintenance of cellular functions. The best part of this technology is that it gives more flexibility to environmental microbiologists to instantly pioneer the immense genetic variability of microbial communities. However, it is intensively complex to identify the suitable sequencing measures of any specific gene that can exclusively indicate the involvement of microbial metagenomes and be able to advance valuable results about these communities. This review provides an overview of the metagenomic advancement that has been advantageous for aggregation of more knowledge about specific genes, microbial communities and its metabolic pathways. More specific drawbacks of metagenomes technology mainly depend on sequence-based analysis. Therefore, this 'targeted based metagenomics' approach will give comprehensive knowledge about the ecological, evolutionary and functional sequence of significantly important genes that naturally exist in living beings either human, animal and microorganisms from distinctive ecosystems.

Resource recovery and circular economy from organic solid waste using aerobic and anaerobic digestion technologies

With the inevitable rise in human population, resource recovery from waste stream is becoming important for a sustainable economy, conservation of the ecosystem as well as for reducing the dependence on the finite natural resources. In this regard, a bio-based circular economy considers organic wastes and residues as potential resources that can be utilized to supply chemicals, nutrients, and fuels needed by mankind. This review explored the role of aerobic and anaerobic digestion technologies for the advancement of a bio-based circular society. The developed routes within the anaerobic digestion domain, such as the production of biogas and other high-value chemicals (volatile fatty acids) were discussed. The potential to recover important nutrients, such as nitrogen through composting, was also addressed. An emphasis was made on the innovative models for improved economics and process performance, which include co-digestion of various organic solid wastes, recovery of multiple bio-products, and integrated bioprocesses.

Vermiconversion of biowastes with low-to-high C/N ratio into value added vermicompost

Seaweed (T1), sugarcane trash (T2), coir pith (T3) and vegetable waste (T4) with cowdung (1:1, w/w) were vermicomposted using Eudrilus eugeniae (50 days). The pH in vermicomposts showed a decrease while electrical conductivity showed increment. The organic matter content, organic carbon, lignin, cellulose, C/N and C/P ratios in vermicompost was significantly lower than compost. Total NPK contents of vermicompost were significantly elevated (P < 0.05) with 12.04-63.75%, 19.05-31.58% and 22.47-42.55%, respectively. The significantly higher growth rate of 1.41 and 7.74 mg/worm/day was observed in T1 on 10th and 50th day respectively, with 23.91 initial C/N ratio; while it was 0.85 and 4.81 mg/worm/day in T4 with 69.81 initial C/N ratio. A similar pattern was reflected in cocoon production, hatchling success and hatchling number/cocoon. Results revealed that vermicompost quality, worm growth, and reproduction depend on C/N ratio. The study suggests that amendment materials like cowdung are necessary to reduce C/N ratio for effective vermicomposting.

Identification of phytochemical components from Aerva lanata (Linn.) medicinal plants and its in-vitro inhibitory activity against drug resistant microbial pathogens and antioxidant properties

This study aimed to determine the phytochemical components, microbial inhibitory effectiveness and antioxidant properties of Aerva lanata plant extracts. The whole plant showed various medicinal applications in folklore and traditional medicine in various parts of the world. The organic extracts such as ethanol, ethyl acetate, chloroform, acetone, water and methanol were subjected for various phytochemical analysis and confirmed for the existence of flavonoids, glycosides, terpenoids and alkaloid containing components. Alternatively, the extracts were performed for the antibacterial activities against the microbial pathogens and antioxidant properties. Results indicated that, the solvent extracts showed prominent activity against the tested strains. The MIC concentrations of plant were detected from 5 mg/ml to 40 mg/ml. The plant extract was highly effective against E. coli and E. aerogenes and the MIC was 5 mg/ml. In addition, the extracts noted promising antioxidant activities. The antioxidant activities were dose dependent manner. In conclusion, A. lanata extracts showed that significant major phytochemicals and effective antioxidant and anti-microbial properties.

Host metabolic responses to Plasmodium falciparum infections evaluated by 1H NMR metabolomics

The human malarial parasite Plasmodium falciparum causes the most severe forms of malarial infections, which include cerebral malaria and various organ dysfunctions amongst adults in India. So far no dependable clinical descriptor is available that can distinguish cerebral malaria from other symptomatically similar diseases such as sepsis and encephalitis. This study aims at evaluating the differential metabolic features of plasma samples from P. falciparum patients with varying severities, and patients suffering from symptomatically similar diseases. ¹H Nuclear Magnetic Resonance (NMR) based metabolic profiling of the plasma of the infected individuals and the control population was performed. The differences in the plasma profiles were evaluated through multivariate statistical analyses. The results suggest malaria-specific elevation of plasma lipoproteins. Such an increase was absent in control populations. In addition, cerebral malaria patients exhibited a decrease in plasma glycoproteins; such a reduction was not observed in malarial patients without cerebral symptoms. The data presented here indicates that the metabolism and/or transport of the plasma lipids is specifically perturbed by malarial infections. The differential perturbation of the plasma glycoprotein levels in cerebral malaria patients may have important implications in the diagnosis of cerebral malaria.

Nutrient status and phytotoxicity analysis of goat manure discharged from farms in South Korea

The present study evaluated the phytotoxicity effect of goat manure (GM) collected from six different regions in South Korea, namely, Chupungnyeong (T1), Hoengseong (T2), Goesan (T3), Sancheong (T4), Jangsu (T5) and Namwon (T6). Phytotoxicity was assessed by means of the analysis of germination index (GI), relative seed germination (RSG), relative root elongation (RRE) and vigor index (VI) using five commercial crop varieties, namely, sesame (Sesamum indicum L.), chrysanthemum (Chrysanthemum indicum L.), carrot (Daucus carota), radish (Raphanus sativus) and cabbage (Brassica rapa). Physico-chemical parameter values were recorded at appreciable levels in all GM extracts. The effect of seedling growth was significantly different (p ≤ .05) due to the variability of nutrient content and phytotoxic effect of the extracts on the different crop seeds. Of the extracts, Goesan (T3) and Sancheong (T4) recorded the best results in the range of GI (%) (54.1-128.8) and VI (930.7-1044) and GI (%) (70.1-167.3) and VI (609.2-3034), respectively, and also showed no inhibitory effect in any of the crop seeds. Overall results also revealed that radish crops showed excellent and non-phytotoxic results in all manure extracts compared to the other crops.

Bio-optimization of the carbon-to-nitrogen ratio for efficient vermicomposting of chicken manure and waste paper using Eisenia fetida

The main objective of the present study was to determine the optimum C/N ratio for converting waste paper and chicken manure to nutrient-rich manure with minimum toxicity. Six treatments of C/N ratio 20, 30, 40, 50, 60, and 70 (T1, T2, T3, T4, T5, and T6, respectively) achieved by mixing chicken manure with shredded paper were used. The study involved a composting stage for 20 days followed by vermicomposting with Eisenia fetida for 7 weeks. The results revealed that 20 days of composting considerably degraded the organic waste mixtures from all treatments and a further 7 weeks of vermiculture significantly improved the bioconversion and nutrient value of all treatments. The C/N ratio of 40 (T3) resulted in the best quality vermicompost compared to the other treatments. Earthworm biomass was highest at T3 and T4 possibly due to a greater reduction of toxic substances in these waste mixtures. The total N, total P, and total K concentrations increased with time while total carbon, C/N ratio, electrical conductivity (EC), and heavy metal content gradually decreased with time during the vermicomposting process. Scanning electron microscopy (SEM) revealed the intrastructural degradation of the chicken manure and shredded paper matrix which confirmed the extent of biodegradation of treatment mixtures as result of the composting and vermicomposting processes. Phytotoxicity evaluation of final vermicomposts using tomato (Lycopersicon esculentum), radish (Raphanus sativus), carrot (Daucus carota), and onion (Allium cepa) as test crops showed the non-phytotoxicity of the vermicomposts to be in the order T3 > T4 > T2 > T1 > T5 > T6. Generally, the results indicated that the combination of composting and vermicomposting processes is a good strategy for the management of chicken manure/paper waste mixtures and that the ideal C/N ratio of the waste mixture is 40 (T3).

Evaluation of phytotoxicity effect on selected crops using treated and untreated wastewater from different configurative domestic wastewater plants

This study investigated the phytotoxicity effect of untreated and treated wastewater collected from two different configurations of domestic wastewater treatment plants in South Africa. The phytotoxicity effect on vegetable seed growth was studied in terms of germination index (GI), relative seed germination (RSG) and relative root elongation (RRE) using four commercial crop varieties, viz., tomato (Lycopersicon esculentum), radish (Raphanus sativus), carrot (Daucus carota) and onion (Allium cepa). According to phyototoxicity limits, 80% germination and above is regarded as non-toxic and less than 50% GI is regarded as highly toxic and not suitable for agricultural purposes. In our study, seeds were irrigated with concentrations of 25%, 50%, 75%, 100% of treated effluent (TE) and untreated effluent (UTE). The TE results were best with the highest GI (%) recorded as tomato, 177; carrot, 158.5; onion, 132; and lettuce, 124. The results of this study indicate that TE showed no phytotoxicty effects and recorded above 80% GI. The UTE irrigated crops reached a GI of only 50% and above which is clear evidence of the beneficial effect of waste water treatment. The overall results confirmed that treated wastewater has a beneficial effect on agricultural crops and can be used as a liquid fertilizer.

Influence of fermented tannery solid waste on morphological, biochemical, yield and nutritional responses of tomato plants

The non-tanned proteinaceous tannery solid waste animal fleshing (ANFL), containing high nutritive value, was hydrolyzed using bacteria Selenomonas ruminantium HM000123 through submerged (SmF) and solid-state (SSF) fermentation processes. In addition, the effects of ANFL fermentative hydrolysate on growth, yield and biochemical properties of tomato plants were investigated. The treatments included T1 (SmF-ANFL), T2 (SSF-ANFL), T3 (recommended dose of NPK fertilizers) and a control without any amendment. Hydrolysates of both SmF-ANFL and SSF-ANFL treatments increased the biomass and yield as evidenced by plant height, stem girth, number of leaves and fruit yield when compared with both NPK and control plants. In this 90-day study, significant (p ≤ 0.05) changes were observed in SSF-ANFL treated plants compared to the other treatments. Protein profile analyzed through SDS-PAGE indicates the expression of a high molecular weight protein (205 kDa) and other proteins in the leaves of the SSF-ANFL treated plants. Overall results revealed that SSF-ANFL can be successfully utilized as a fertilizer particularly for cultivating tomato plants.

Nutrient and enzymatic changes of hydrolysed tannery solid waste treated with epigeic earthworm Eudrilus eugeniae and phytotoxicity assessment on selected commercial crops

Animal fleshing (ANFL) is the predominant proteinaceous solid waste generated during processing of leather and it is confronting disposal problems. The aim of this study was to assess the potential of epigeic earthworm Eudrilus eugeniae to utilize and transform the fermented ANFL in the solid state (SSF) and submerged state (SmF) into a value added product along a low residence period (25 days). A total of six treatment units containing different waste mixture compositions were established. Fifty healthy and non-clitellated earthworms were introduced in three different treatment containers: control, SSF, and SmF (+worm). Another set of treatment mixtures (control, SSF, SmF) was established without earthworms (-worm) to compare the results. The products were characterized for physico-chemical, enzymatic analysis and seedling growth parameters to compare the differences in the process with and without earthworms. The changes observed in the analytical parameters were in the following order: SSF > SmF > control mixtures (p < 0.05). The vermicompost showed a significant reduction in heavy metals, total organic carbon and an increase in total Kjeldhal nitrogen as compared to the product untreated by earthworms. The maximum enzymatic activities were observed after 21 days of vermicomposting. The relative seed germination of vermicompost extracts were in the order of tomato (Lycopersicon esculentum) > green gram (Vigna radiata) > cucumber (Cucumis sativus) > bottle gourd (Lagenaria siceraria (Mol.) Standl.) and showed no phytotoxicity effects. The results indicated that the combination of both ANFL hydrolysis through fermentation and vermicomposting is a good alternative to the management of this kind of waste.

Efficient Computation of the Shapley Value for Game-Theoretic Network Centrality

The Shapley value---probably the most important normative payoff division scheme in coalitional games---has recently been advocated as a useful measure of centrality in networks. However, although this approach has a variety of real-world applications (including social and organisational networks, biological networks and communication networks), its computational properties have not been widely studied. To date, the only practicable approach to compute Shapley value-based centrality has been via Monte Carlo simulations which are computationally expensive and not guaranteed to give an exact answer. Against this background, this paper presents the first study of the computational aspects of the Shapley value for network centralities. Specifically, we develop exact analytical formulae for Shapley value-based centrality in both weighted and unweighted networks and develop efficient (polynomial time) and exact algorithms based on them. We empirically evaluate these algorithms on two real-life examples (an infrastructure network representing the topology of the Western States Power Grid and a collaboration network from the field of astrophysics) and demonstrate that they deliver significant speedups over the Monte Carlo approach. For instance, in the case of unweighted networks our algorithms are able to return the exact solution about 1600 times faster than the Monte Carlo approximation, even if we allow for a generous 10% error margin for the latter method.

Multi-view methods for protein structure comparison using latent dirichlet allocation

Motivation: With rapidly expanding protein structure databases, efficiently retrieving structures similar to a given protein is an important problem. It involves two major issues: (i) effective protein structure representation that captures inherent relationship between fragments and facilitates efficient comparison between the structures and (ii) effective framework to address different retrieval requirements. Recently, researchers proposed vector space model of proteins using bag of fragments representation (FragBag), which corresponds to the basic information retrieval model.

Results: In this article, we propose an improved representation of protein structures using latent dirichlet allocation topic model. Another important requirement is to retrieve proteins, whether they are either close or remote homologs. In order to meet diverse objectives, we propose multi-viewpoint based framework that combines multiple representations and retrieval techniques. We compare the proposed representation and retrieval framework on the benchmark dataset developed by Kolodny and co-workers. The results indicate that the proposed techniques outperform state-of-the-art methods.

Availability:http://www.cse.iitm.ac.in/~ashishvt/research/protein-lda/.

Contact:ashishvt@cse.iitm.ac.in

Bacterial composting of animal fleshing generated from tannery industries

Animal fleshing (ANFL) is the major proteinaceous solid waste generated during the manufacture of leather, which requires to be disposed of by environmentally sound manner. This study reports about the treatment of ANFL into an organic compost and its effects on physiological parameters of different crops in a laboratory study. The ANFL was hydrolysed using Selenomonas ruminantium HM000123 and then the hydrolysed ANFL was mixed with cow dung and leaf litter for producing composted organic fertilizer (COF). The COF was characterized for pH, electrical conductivity (EC), total Kjeldhal nitrogen (TKN), and total organic carbon (TOC). The composting resulted in a significant reduction in pH, TOC and C:N ratio and an increase in TKN after 49 days in a compost reactor. Scanning electron microscope and FT-IR were used to analyse the hydrolysis of intra structural ANFL matrix and changes in the functional groups, respectively, in initial and final day COF. Thermogravimetry (TG) analysis was carried out for the raw mixture and COF samples to identify the weight loss under the nitrogen environment. The relative seed germination was found to be 94% in tomato (Lycopersicon esculentum), 92% in green gram (Vigna radiata), 86% in bottle gourd (Lagenaria siceraria (Mol.) Standl.) and 84% in cucumber (Cucumis sativus L.) using the extracts of COF. The results indicate that the combination of both hydrolysis and bacterial composting reduced the overall time required for composting and producing a nutrient-enriched compost product.

Modeling basal ganglia for understanding Parkinsonian reaching movements

We present a computational model that highlights the role of basal ganglia (BG) in generating simple reaching movements. The model is cast within the reinforcement learning (RL) framework with correspondence between RL components and neuroanatomy as follows: dopamine signal of substantia nigra pars compacta as the temporal difference error, striatum as the substrate for the critic, and the motor cortex as the actor. A key feature of this neurobiological interpretation is our hypothesis that the indirect pathway is the explorer. Chaotic activity, originating from the indirect pathway part of the model, drives the wandering, exploratory movements of the arm. Thus, the direct pathway subserves exploitation, while the indirect pathway subserves exploration. The motor cortex becomes more and more independent of the corrective influence of BG as training progresses. Reaching trajectories show diminishing variability with training. Reaching movements associated with Parkinson's disease (PD) are simulated by reducing dopamine and degrading the complexity of indirect pathway dynamics by switching it from chaotic to periodic behavior. Under the simulated PD conditions, the arm exhibits PD motor symptoms like tremor, bradykinesia and undershooting. The model echoes the notion that PD is a dynamical disease.

Oxidative destabilization of dissolved organics and E. coli in domestic wastewater through immobilized cell reactor system

Domestic wastewater contains a considerable amount of pathogenic organisms besides non-biodegradable organics. The conventional technologies followed for the treatment of domestic wastewater are less efficient in removing pathogenic organisms despite substantial removal of dissolved organics. The focal theme of the present investigation was to use a chemo-autotrophic activated carbon oxidation (CAACO) system, an immobilized cell reactor using chemoautotrophs (Bacillus sp.) for the treatment of domestic wastewater. The oxidation of organics and Escherichia coli in wastewater is controlled by the parameters space time, O(2)/COD, bed height and cod loading. The scheme comprised of anaerobic treatment, sand filtration and CAACO treatment removed BOD. COD, Total organic carbon (TOC), dissolved protein, total Kjeldhal nitrogen (TKN) and bacterial count (most probable number (MPN)) by 81%, 92%, 84%, 94%, 93% and 99.9997%, respectively. The low concentration of E. coli in the CAACO-treated wastewater was completely eliminated through UV irradiation in 3 min at 254 nm.

Detection of adult Brugia malayi filariae by ultrasonography in humans in India and Indonesia

In bancroftian filariasis, ultrasonography (USG) is a suitable tool to monitor infection by the detection of adult filariae in addition to antigen detection tests (ICT, Og4C3). However, in brugian filariasis, ultrasound examinations in humans have so far failed to detect adult worms and no antigen test is available to verify infections in patients who are carriers of adult worms but amicrofilaraemic. In this study, we describe the feasibility of detection of adult Brugia malayi filariae by USG. Worm nests were detected in 4 of 32 patients in India and Indonesia, located in the breast, the thigh, the calf and an inguinal lymph node. The study shows that adult filariae of B. malayi in humans can be detected by USG, but the technique is limited by the fact that worm nests seem not to be stable over time in humans, as is the case in bancroftian filariasis.

How specific is the immune response to malaria in adults living in endemic areas?

It is documented that people living in malaria endemic areas acquire immunity against malaria after repeated infections. Studies involving passive transfer of IgG from immune adults to the nonimmune subjects have shown that circulating antibodies play an important role, and that immune adults possess protective antibodies, which susceptible malaria patients do not. Through a differential immunoscreen, we have identified several novel cDNA clones, which react exclusively and yet extensively with immune sera samples. Specific antisera raised against the immunoclones inhibit the growth of parasites in culture. The clones studied so far turn out to be novel conserved Plasmodium genes. In order to study the response of sera of adults from malaria endemic areas of India and Africa to these immunogens, we carried out ELISA assays using these immunopeptides, other P. falciparum specific antigens, peptides, antigens from other infections such as mycobacterial infections and other proteins such as BSA. Children from the same areas and normal healthy urban people showed very little activity to each of these categories. A large percentage of adults from endemic areas responded positively to all the malarial immunogens tested. However, the same persons also showed high response to other antigens and proteins as well. The implications of these results are reported in this paper.

Pentoxifylline adjunct improves prognosis of human cerebral malaria in adults

Fifty-two adult patients with cerebral malaria were randomly categorized into two groups to receive either quinine dihydrochloride (Qn) alone or a combination of Qn and pentoxifylline (Px). Thirty-two of them received intravenous (i.v.) Qn (group I), and 20 patients (group II) received i.v. Qn along with parenteral Px support (10 mg/kg/day) for the initial 3 days. There was significant improvement in coma resolution time in group II (21.6 +/- 13.9 h) in comparison with group I (63.5 +/- 19.7 h) (P < 0.001), and mortality was 25% of patients in group I against 10% patients receiving Px adjunct (P > 0.05). Three days post-therapy, serum tumour necrosis factor-alpha (TNF-alpha) levels decreased significantly in patients on Px support (day 0 TNF = 415.62 +/- 477.80 pg/ml; day 3 TNF = 47.92 +/- 27.9 pg/ml; P = 0.0029). There was no significant change in TNF levels in those on quinine alone (day 0 TNF = 477.08 +/- 933.90 pg/ml; day 3 TNF = 589 +/- 602.3 pg/ml; P > 0.05). There were no serious side-effects necessitating withdrawal of patients receiving Px therapy.

Bancroftian filariasis: a 13-year follow-up study of asymptomatic microfilariae carriers and endemic normals in Orissa, India

The natural history of human filarial infections leading to development of disease has been a subject of intense debate. The models proposed so far have largely been based on cross-sectional data on microfilariae (Mf) and disease prevalence in filariasis endemic areas. In an attempt to study the parasitological and clinical consequences of filarial infection in Beldal (Orissa, India), an area endemic for Bancroftian filariasis, cohorts of 59 asymptomatic Mf carriers (AS) and 187 asymptomatic and amicrofilaraemic subjects or 'endemic normals' ('EN'), were followed-up and a fraction (73% and 46% respectively) re-examined after 13 years to monitor (a) Mf prevalence, (b) Mf density, (c) circulating filarial antigen (CFA) and (d) chronic disease manifestations. The Mf prevalence and density were also monitored in Mf carriers after 1 and 4 years. Both Mf prevalence and density decreased progressively in the cohort of Mf carriers over a period of 13 years in Beldal. Only 37% of them continued to be microfilaraemic and the Mf density in these subjects was only 10% of the original level. However, loss of circulating Mf in this cohort did not result in loss of CFA and 95% remained CFA positive regardless of Mf status. About 23% of males in the 'EN' cohort developed hydrocoele while only 5.7% of male Mf carriers, who were not treated with DEC, had developed hydrocoele after 13 years. A cohort of Mf carriers in another area, Jatni, was also examined after 10 years to study the parasitological and clinical outcome. In this area, about 59% of the Mf carriers continued to be microfilaraemic after 10 years. These results reveal that in Mf carriers adult filarial worms persist for several years and that loss of circulating Mf with or without chemotherapy with DEC (single 12-day course) does not influence adult worm survival. The findings have been discussed in the context of 'static' and 'dynamic' models describing the relationship between infection and disease in human filariasis.

Human bancroftian filariasis - a role for antibodies to parasite carbohydrates

Studies on immune responses to parasites have been undertaken in filariasis with a view to understand protective immunity, pathogenesis of the disease process and mechanisms of immune deviation. However none of the investigations conducted so far on antibody responses have addressed the issue of immunogenicity of filarial carbohydrate antigens in human lymphatic filariasis. In this communication we report details on relative protein and carbohydrate contents of various developmental stages of filarial parasites and antibody responses to filarial proteins (Fil.Pro) and carbohydrates (Fil.Cho) in different clinical spectrum of human bancroftian filariasis. As expected, antibodies of IgM and IgG2 subclass recognized primarily Fil.Cho while IgG4 filarial antibodies recognized exclusively Fil.Pro. Reactivity of IgG3 to Fil.Cho was similar to that of IgG2 while IgG1 more readily recognized Fil.Pro than Fil.Cho. The IgG2 and IgG3 antibodies to Fil.Cho were found to be significantly more in patients with chronic filarial disease and in endemic normals when compared with microfilariae (mf) carriers while IgG4 antibodies to Fil.Pro were significantly more in mf carriers. The dichotomy in reactivity of filarial IgG2, IgG3 and IgG4 was dependent on active filarial infection as indicated by presence of circulating filarial antigen (CFA). Individuals with CFA were found to possess significantly more IgG4 to Fil.Pro than those without CFA while IgG2 and IgG3 levels to Fil.Cho was significantly more in CFA negative subjects when compared to those with CFA. Although IgG1 reacted more readily with Fil.Pro, unlike IgG4, their levels were significantly more in CFA negative subjects when compared to those with active filarial infection. Absorption of sera with phosphorylcholine (PC) resulted in no significant loss of reactivity to Fil.Cho indicating that most of the anticarbohydrate antibodies were recognizing non-PC determinants in human filariasis. Elevated levels of IgG2 and IgG3 antibodies to Fil.Cho in individuals free of filarial infection indicate a possible role for carbohydrate antigens in induction of protective immunity in human filariasis.

Human Bancroftian filariasis: loss of patent microfilaraemia is not associated with production of antibodies to microfilarial sheath

Antisheath antibodies have been incriminated in elimination of circulating microfilariae in human filariasis since a very significant inverse association has been consistently demonstrated between the two parameters. An attempt was made in the present study to seek empirical proof for the above proposal. Two cohorts of 43 and 73 microfilariae (mf) carriers were examined after 13 and 10 years, respectively, for mf as well as antisheath antibodies. The first cohort was also examined for the presence of circulating filarial antigen (CFA). Of the 43 mf carriers examined after 13 years, 62.8% were free of circulating mf although only 3.7% of them had demonstrable antisheath antibodies. Approximately 93% of this cohort (with or without current microfilaraemia) tested positive for CFA after 13 years indicating continued presence of adult filarial worms in the host after loss of mf in circulation. When the second cohort of 73 mf carriers were examined after 10 years, 30 were found to be amicrofilaraemic and only 6.66% of them had demonstrable antisheath antibodies. We conclude that, in human Bancroftian filariasis, elimination of circulating microfilariae may not be mediated by antibodies to microfilarial sheath.

Are inflammation and immunological hyperactivity needed for filarial parasite development?

Immune-dependent growth and development of infectious agents and pathogenesis of disease are increasingly being recognized. It is proposed that the development of filarial larvae to adult stage parasites takes place in an ambiance of inflammatory T helper cell type 1 cytokines in mammalian hosts, and that susceptibility to filarial infections could be governed by the status of macrophage-derived nitric oxide and host ability to produce antibodies to filarial T-independent (carbohydrate) antigens.

Protective immunity in human Bancroftian filariasis: inverse relationship between antibodies to microfilarial sheath and circulating filarial antigens

The existence and the nature of protective immunity in human filariasis continues to be a subject of intense debate. While there is no broad consensus on functional immunity against larval and adult stage parasites, anti-microfilarial immunity has been demonstrated to be mediated by antibodies to the microfilarial sheath. In the present study, circulating filarial antigens (CFA), a marker of active filarial infection in human Bancroftian filariasis, was found to be inversely associated with antibodies to microfilarial sheath in a cohort of 411 subjects representing all categories of filariasis across the clinical spectrum of the disease. Approximately 80% of humans of all age groups (5-65 years) were found to have either CFA or anti-sheath antibodies. The inverse relationship observed between these two parameters was found to be independent of the clinical manifestation; both symptomatic and asymptomatic cases were found to display similar inverse association between CFA and anti-sheath antibodies. The prevalence of anti-sheath antibodies in the paediatric group was found to be very high as compared to adults; 78% of children below the age of 10 years tested positive for anti-sheath antibodies although the mf rate and CFA rate were only 4.5% and 22.7%, respectively, in this age group, indicating that developing larvae or juvenile adult stage parasites could have been the source of antigenic stimulus for induction of antibodies to the microfilarial sheath.

Setaria digitata infections in cattle: parasite load, microfilaraemia status and relationship to immune response

A total of 110 cattle were examined in an area endemic for Bancroftian filariasis for the prevalence of infection of the bovine filarial parasite Setaria digitata. About 12.5% of cattle were found to harbour both adult worms in the peritoneum and microfilariae (mf) in circulation; 70% of the cattle were amicrofilaraemic but with an adult worm infection. A third group of cattle (16.5%) was free of detectable mf and adult worms. The presence of adult worms and/or mf did not influence the antibody levels to any of the four antigen preparations of S. digitata. However, there was a significant inverse relationship between the presence of antibodies to microfilarial sheaths and the absence of circulating mf as shown by the immunoperoxidase assay. Cattle immunoglobulin containing high titres of anti-sheath antibodies cleared circulating microfilariae very effectively in Mastomys coucha thus demonstrating the protective nature of anti-sheath antibodies in eliminating circulating microfilariae in vivo.

Detection of antigen-specific human serum proteins related to the T-cell receptor in infectious disease and in an immune response to milk proteins or chemicals

A monoclonal IgG2 antibody, MG3C9-1 A12, was prepared by immunization of mice with human serum Cohn Fraction III proteins enriched for TCR Ca+ proteins. MG3C9-1 A12 bound to Mr 28,000, antigen-specific TCR Ca+, beta-, and TCR Ca+, beta+ serum proteins associated with TGF-beta1, 2. The IgG2 monoclonal antibody also bound to T-lymphocyte proteins but did not bind to B lymphocyte proteins, human albumin, IgM, IgG, IgA, or TGF-beta1, 2, 3 immunogenic peptides. Monoclonal MG3C9-1 A12 detected TCR-related proteins specific for filarial extract, milk proteins, or benzoic acid in the sera of individuals with chronic or asymptomatic filariasis, milk intolerance, or sensitivity to toluene, respectively. TCR-related serum proteins were also detected intracellularly in mononuclear cells in frozen sections of ileum from a patient with milk intolerance and reactive mesenteric lymph nodes from a patient with a gastric ulcer. The results suggest that antigen-specific TCR-related serum proteins may be elevated during an immune response to oral, environmental, or infectious stimuli.

Urinary diversion after total pelvic exenteration for rectal cancer

BACKGROUND

Total cystectomy is indicated for the treatment of bulky primary rectal cancers as well as previously treated, locally recurrent tumors that invade the bladder, prostate, seminal vesicle, or urethra. We review a 10-year Memorial Sloan-Kettering Cancer Center experience with urinary diversion in this setting.

METHODS

Between April 1988 and June 1998, 47 patients underwent urinary diversion during a total pelvic exenteration for rectal cancer. Charts and operative records were reviewed to determine pathological findings, short-term and long-term urological complications, and survival.

RESULTS

Forty-seven patients (25 males and 22 females; median age, 62 years; age range, 27-79 years) were included. Sixteen (34%) patients underwent cystectomy for a primary rectal tumor (including 1 for rectal sarcoma and 1 for synchronous invasive bladder cancer), and 31 (66%) patients underwent surgery for a locally recurrent rectal cancer. Thirty (64%) patients underwent preoperative, 18 (38%) underwent intraoperative, and 11 (23%) underwent postoperative radiotherapy. Twenty-six (55%) patients received preoperative and 16 (34%) underwent postoperative chemotherapy. Two patients had continent ileal cecal reservoirs, 1 a colonic conduit, and the remaining 45 had ileal conduits. The tumor invaded the bladder in 24 (51%) patients, the prostate in 5 (11%) patients, and the seminal vesicle in 5 (11%) patients. Complete resection was achieved in 42 (89%) patients. There were a total of eight complications in eight (17%) patients. There were three early complications, two of which were ileoureteral anastomotic leaks, one managed by reoperation, the second by percutaneous drainage, and one moderate hydronephrosis managed expectantly. There were five late complications; three patients had ureteral stricture/stenosis, leading to nephrectomy in one patient and percutaneous stenting in two patients. Two patients developed late hydronephrosis, so far managed expectantly. There was one perioperative death. After a median follow-up of 16.83 months, 20 patients were dead of the disease, 6 were alive with disease recurrence, 2 were dead of other causes, and 19 had no evidence of disease. Three-year actuarial disease-specific survival was 34%.

CONCLUSIONS

Complete resection of bulky primary or locally recurrent rectal cancer can be performed with acceptable urological morbidity. Complete resection was obtained in 89% of patients, with 72% having urological organ invasion. Overall urological complications of 17% are acceptably low despite intensive perioperative radiation and chemotherapy. Disease-specific survival in these patients remains limited.

Naturally occurring alpha-galactosyl antibodies in human sera display polyreactivity

Anti-gal is a dominant autoantibody constituting nearly 1% of total circulating IgG in humans and old world primates. Raised levels of anti-gal have been demonstrated in parasitic diseases such as malaria, leishmaniasis and Chagas disease and in a variety of autoimmune diseases. It has also been implicated as a primary cause of rejection of xenogeneic cells and organs transplanted in old world primates since Gal-alpha 1,3 Gal is thought to be the major antigenic epitope to which xenoreactive natural antibodies bind. Since polyreactive antibodies have also been widely implicated in xenotransplantation and anti-gal is yet to be demonstrated to be polyreactive, we have attempted to study this property of anti-gal antibodies. Anti-gal levels were assayed in 72 human sera and compared with DNA-binding antibodies. A significant positive correlation was found between anti-gal and DNA-binding antibodies. Absorption of sera with fresh rabbit erythrocytes (which express abundant alpha-galactose on their surface) resulted in significant removal of both anti-gal and DNA-binding antibodies. Affinity purified anti-gal were found to be reactive to DNA, actin, myosin and tubulin indicating the polyreactive nature of naturally occurring anti-gal antibodies in human sera. The observed polyreactivity was not an exclusive feature of sera collected from tropical countries-anti-gal affinity purified from sera of North Americans were also found to react with DNA. The demonstration of polyreactivity of anti-gal indicates a much wider biological role for this autoantibody in humans and old world primates.

Bruton's tyrosine kinase deficiency in macrophages inhibits nitric oxide generation leading to enhancement of IL-12 induction

We show that macrophages of X-linked immunodeficient mice with a mutant nonfunctional Bruton's tyrosine kinase produce less NO than wild-type macrophages in response to a variety of stimuli. Induction of the inducible NO synthase (iNOS) protein, the transcription factor IFN regulatory factor-1 involved in iNOS expression, and the transcription factor STAT-1 involved in regulating IFN regulatory factor-1 induction are all poorer in X-linked immunodeficient than in wild-type macrophages. On the other hand, induction of IL-12 is higher in X-linked immunodeficient than in wild-type macrophages. Macrophage IL-12 induction is enhanced by iNOS inhibitors such as aminoguanidine and thiocitrulline and is inhibited by NO generation via sodium nitroprusside. There is relative enhancement of IFN-gamma production by immune T cells from mice immunized under aminoguanidine cover. Our data thus suggest that Bruton's tyrosine kinase participates in signaling for iNOS induction via IFN regulatory factor-1 in macrophages and that NO is an inhibitor of IL-12 induction.

Delayed clearance of filarial infection and enhanced Th1 immunity due to modulation of macrophage APC functions in xid mice

Bruton's tyrosine kinase (Btk) mutant CBA/N mice show delayed clearance of injected microfilaria (mf) compared with wild-type CBA/J mice. Anti-mf T cells from CBA/N mice make relatively more IFN-gamma than those from CBA/J mice. The anti-mf T cell proliferative responses are also greater in CBA/N mice. This CBA/N immune phenotype is not restricted to filarial Ags, because immunization with pure proteins also yields T cell responses of greater proliferative magnitude skewed away from Th2 cytokines in CBA/N compared with CBA/J mice. The increased magnitude of CBA/N T cell proliferative responses is reflected in increases in both precursor frequencies and clonal burst sizes of responding Ag-specific T cells, and is independent of the source of re-stimulating APCs. Transfer of CBA/J peritoneal resident cells (PRCs) into CBA/N mice before pure protein immunization leads to a wild-type immune phenotype in the recipient CBA/N mice, with a reduction in the proliferative response and a relative decrease in the IFN-gamma produced. When wild-type PRC subpopulations are similarly transferred, the wild-type immune phenotype is transferred by macrophages rather than by B cells. Transfer of wild-type PRCs into CBA/N mice before injection of mf also causes similar changes in the anti-mf T cell responses and enhances the clearance of mf. Thus, Btk is involved in critical macrophage APC functions regulating priming of T cells, and can modulate these responses in pathophysiologically relevant fashion in vivo.

Lymphatic filariasis and malaria: concomitant parasitism in Orissa, India

Concomitant parasitism with Plasmodium spp. and Wuchereria bancrofti was examined in Orissa, India, to study the influence of one parasite infection on the other in human communities. A survey of 1815 nocturnal blood films in 11 villages indicated an overall prevalence of 9.6% for malaria and 8.5% for microfilaraemia. Only 0.3% of the population harboured both parasites. Analysis of the expected and observed distribution of cases of dual infection in each village did not indicate any significant interaction between the 2 infections. The malarial vector density in 3 selected villages correlated well with the prevalence rate of malaria.

Antibodies to diethylcarbamazine potentiate the antifilarial activity of the drug

The antifilarial drug diethylcarbamazine citrate (DEC) is known to mediate in vivo microfilaricidal activity in conjunction with the host immune system. In this study passive transfer of antibodies to DEC elicited by immunization with methyl piperazine carboxylic acid (MPCA) coupled to bovine serum albumin (BSA), was found to potentiate microfilaricidal activity of subcurative doses of DEC in Setaria digitata infected Mastomys coucha. Active immunization of microfilaraemic animals with MPCA-BSA followed by administration of subcurative doses of DEC also resulted in rapid clearance of microfilaraemia in both S. digitata and Brugia malayi infected M. coucha indicating the synergistic activity of DEC and the antibodies to the drug. Since some of the filarial antibodies are known to react with DEC, it is proposed that such antibodies may potentiate the microfilaricidal activity of the drug in vivo.

Engagement in Academic Work: The Role of Learning Goals, Future Consequences, Pleasing Others, and Perceived Ability

Engagement in academic work was viewed from a multiple goals perspective. Two studies were conducted in which high school math students completed an instrument measuring five goals students might have for doing academic work (learning goals, performance goals, obtaining future consequences, pleasing the teacher, and pleasing the family), perceived math ability, self-regulatory activities, strategies (deep or shallow) used when studying for math, and the amount of effort and persistence expended on the class. Factor analysis indicated that the five goals scales and the perceived ability scale represented unique factors. The correlations among the variables revealed theoretically consistent interrelationships. Multiple regression analyses indicated that various goals (e.g., learning goals, obtaining future consequences, and pleasing the teacher), perceived ability, and some interactions accounted for significant amounts of variance in the task engagement measures (self-regulation, strategy use, effort, and persistence) and achievement. Results are discussed in relation to current theory and their practical implications.

Setaria digitata microfilaraemia in Mastomys coucha: an animal model for chemotherapeutic and immunobiological studies

Intraperitoneal implantation of adult gravid females of the bovine filarial parasite, Setaria digitata in Mastomys coucha was found to induce microfilaraemia lasting for about 125 days. The microfilariae (mf) could be detected as early as 4 days post-implantation (p.i.) and peak levels of about 30 mf in 20 microliters of blood were observed by 21 days. A significant positive correlation was found between mf density and the body weight of recipients pre-implantation. The implanted adult worms were generally viable only for less than 1 week. Implantation resulted in a significant decrease in total leucocytes and erythrocytes, induction of eosinophilia, splenomegaly and anti-erythrocyte autoantibodies. The microfilariae in circulation developed into 3rd-stage infective larvae (L3) when fed onto Aedes aegypti (refm, Liverpool strain). The mf in circulation were found to be eliminated by oral administration of diethylcarbamazine citrate, indicating the usefulness of this model for screening potential anti-microfilarial drugs. During the microfilaraemic phase, priming with tetanus toxoid (TT) resulted in significantly decreased production of anti-toxin levels indicating a state of generalized immunosuppression. Induction of antibodies to various fractionated antigenic components of adult parasites could be demonstrated by enzyme immunoassay (EIA) in M. coucha implanted with live or cold-stunned adult worms. The S. digitata-M. coucha model thus is found amenable to perform chemotherapeutic and immunobiological investigations in experimental filariasis.

A role for tumour necrosis factor-alpha in acute lymphatic filariasis

A spectrum of clinical manifestations is a feature of human lymphatic filariasis. The acute disease is characterized by periodic and self limiting episodes of adenolymphangitis, fever and associated constitutional symptoms, while the chronic disease includes long lasting manifestations such as lymphoedema and/or hydrocoele. The microfilariae carriers are generally free of clinical symptoms. In the present study circulating Tumour Necrosis Factor (TNF-alpha) was measured in human bancroftian filariasis with different clinical manifestations. Significantly elevated levels were observed only in patients with acute disease and not in microfilariae carriers or in patients with chronic manifestations. A detailed analysis of the acute cases indicated an absence of correlation between TNF-alpha levels and duration of the episodes. However, a significant positive correlation was observed between the severity of the disease and the TNF-alpha levels. About 85% of the acute cases with severe manifestations showed raised levels of TNF-alpha while only 6.5% of mild cases showed such levels. Manifestation of fever was also significantly associated with higher levels of TNF-alpha-while 80% of acute cases with fever had significant levels only 24% of acute cases without fever had high levels of TNF-alpha. Based on these observations we propose a mediatory role for TNF-alpha in acute filariasis and the possible use of TNF-alpha inhibitors for clinical management of the disease.

A quantitative cell-ELISA for alpha-galactose specific antibodies in human malaria

Naturally occurring antibodies to alpha-linked galactose (anti- gal) has been reported to be present in large quantities in normal human sera and they seem to play an important role in a variety of infectious as well as autoimmune diseases. A cell-ELISA using glutaraldehyde fixed normal rabbit erythrocytes was developed for quantification of anti-gal in human sera. This assay was compared with three other(commonly used) immunoassays viz. a) agglutination b) enhanced agglutination and c) lipid ELISA-assays for detection of anti-gal in human sera. The cell-ELISA was found to be the most sensitive assay followed by lipid-ELISA, enhanced agglutination and agglutination assay in decreasing order. Anti-gal affinity purified through a column of melibiose-agarose was tested by cell-ELISA. Monolayers of RRBC pre-treated with alpha-galactosidase was not reactive while in monolayers treated with beta-galactosidase, the anti-gal reactivity was comparable to those in untreated RRBC monolayer, thus indicating the high specificity of cell-ELISA for detection of antibodies to alpha-linked galactose.

A prognostic role for anti-phosphatidyl choline antibodies in human cerebral malaria

Anti-phosphatidyl choline antibodies (alphaPC) have been measured in adult patients from Orissa, India with Plasmodium falciparum infection of varying clinical severity. Significantly raised levels of alphaPC were observed in infected individuals in comparison with controls. The IgG alphaPC were found to be generally more than IgM alphaPC in most cases. The IgG alphaPC levels were significantly more in those cases of cerebral malaria who recovered fully after quinine administration in comparison with fatal cases not responding to quinine therapy, indicating a role for alphaPC in prognosis of adult cerebral malaria. There was no significant difference in levels of alphaPC IgG between non-cerebral and fatal cerebral malaria patients, indicating an absence of a direct protective role in the development of cerebral manifestations. Subgroup typing of IgG with alphaPC activity indicated IgG3 to be the predominant type, followed by IgG2, IgG1 and IgG4. A significant inverse relationship between serum tumour necrosis factor-alpha (TNF-alpha) levels and IgG1 antibodies with alphaPC activity was found, emphasizing the importance of alphaPC in modifying disease severity. These observations appear to give credence to recent reports in the literature indicating that toxic malarial antigens consist of phospholipids and that antibodies to phospholipids (alphaPL) inhibit such antigens in experimental systems.

Bancroftian filariasis-differential reactivity of anti-sheath antibodies in microfilariae carriers

Anti-sheath antibodies have been detected using an immunofluorescent assay (IFAT) in the sera of microfilariae carriers (AS cases) residing in areas endemic for Bancroftian filariasis. Microfilariae (mf) of Wuchereria bancrofti purified from five different mf carriers were used separately as antigen to identify anti-sheath antibodies. The reactivity of sera from AS cases to mf sheath was found to be variable to the five different mf preparations. While as high as 25% of the sera reacted with mf purified from one individual, none of them reacted with mf purified from two other individuals. Such a differential reactivity to the sheath was found to be a feature of antibodies in AS cases only. Sera of seven amicrofilaraemic patients with elephantiasis reacted uniformly with all five mf preparations. The possible existence of polymorphic antigen(s) on the sheath of W. bancrofti mf has been proposed.

Novel proteins of Plasmodium falciparum identified by differential immunoscreening using immune and patient sera

A differential serological screen of a lambda gt11 cDNA expression library of Plasmodium falciparum was performed in an attempt to identify novel and putative host-protective antigens of the parasite. The screening was done with two categories of sera: (i) acute-phase sera obtained from smear-positive acutely infected P. falciparum patients from various regions in India and (ii) immune sera taken from healthy, permanent adult residents of P. falciparum-endemic rural districts of Orissa in eastern India. These adults had not suffered from any clinical malarial symptoms for at least the previous 3 years at the time of serum collection. Sixty-five clones obtained by screening the lambda gt11 library with two immune serum samples were analyzed extensively with a total of 70 acutely infected patient serum samples. Eight of these clones failed to react with any of the patient sera. Each of these eight clones, when tested individually with 92 serum samples from the immune group, reacted with a minimum of 43% of the samples from this category of sera. Thus, these eight epitopes may encode host-protective elements since they are not recognized by antibodies in the patient sera but react exclusively and extensively with the clinically immune set. Sequence analysis of two of these clones reveals that they are novel Plasmodium genes.

Murine malaria: anti-erythrocytic antibodies recognize N-acetyl neuraminic acid residues

A cell-ELISA was developed using monolayers of glutaraldehyde-fixed normal as well as Plasmodium berghei-infected mouse erythrocytes for quantification and characterization of anti-erythrocytic autoantibodies in murine malaria. Testing normal (NMS) and peak parasitaemic sera (PPS) on erythrocyte monolayers treated with trypsin, sodium meta periodate, neuraminidase or heat, and competitive inhibition of antibodies with soluble sialic acid, revealed that some anti-erythrocytic antibodies (which increase during the parasitaemic phase of infection) recognize N-acetyl neuraminic acid (NANA) residues on host erythrocytes. High levels of antibodies to NANA covalently conjugated to bovine serum albumin (BSA) were detectable in PPS. Such antibodies could be significantly absorbed out by preincubation of PPS with mouse erythrocytes (MRBC). Antibodies in PPS, when affinity-purified on a column of Fetuin-Agarose, were found to be reactive to normal as well as parasitized erythrocyte monolayers. Immunoglobulin isotyping and IgG subgroup typing revealed that most of the anti-erythrocytic autoantibodies in NMS were IgM and IgA, while in PPS there was an appreciable increase in IgG2a and IgG3. Affinity-purified anti-NANA antibodies reacted with DNA when tested in an ELISA. There was a significant positive correlation between anti-erythrocytic antibody and DNA-binding levels in NMS as well as PPS. The DNA-binding antibodies in PPS could be effectively absorbed out by preincubation of sera with fresh MRBC. Affinity determination of anti-erythrocytic antibodies eluted from MRBC revealed binding characteristics in the following order: MRBC > single-stranded DNA > double-stranded DNA.

Human cerebral malaria: characterization of malarial antibodies in cerebrospinal fluid

Anti-malarial antibodies were quantified in cerebrospinal fluid (CSF) of 17 cases of cerebral malaria, 16 presumptive cases (no demonstrable parasitaemia in peripheral blood but responding to i.v. quinine therapy) of cerebral malaria, and 15 controls. A schizont-enriched Plasmodium knowlesi antigen was used in an ELISA. Anti-malarial antibodies of IgA and IgM isotypes were not detectable in most of the CSF samples analysed, although serum antibody titres were high. However, 88% of CSF from cerebral malaria and 56% of presumptive cerebral malaria cases had significant levels of IgG anti-malarial antibodies in comparison to control CSF. The antibody levels did not correlate with the severity of coma but correlated well with the duration of coma. The CSF malarial antibody titres were independent of degree of parasitaemia. The possible role of CSF anti-malarial antibodies in cerebral malaria in the light of recent demonstrations of intrathecal synthesis of immunoglobulins and deposition of immune complex in cerebral tissues is discussed.