A biologically active lectin of enteroaggregative Escherichia coli

The pathogenesis of enteroaggregative Escherichia coli, a major contributor to paediatric diarrhoea, is still not clearly understood. A complex carbohydrate specific lectin was identified from the culture supernatant of an enteroaggregative E. coli strain. The lectin was purified to 660-fold by a combination of sequential saturated ammonium sulphate precipitation and gel filtration chromatography in the FPLC system. The homogeneity of the purified lectin was established by analytical isoelectrofocusing [pI 6.75]. Hemagglutination of rabbit erythrocytes by the purified lectin was best inhibited by fetuin. The N-terminal sequence of the 41.7 kDa subunit showed homology to the outermembrane porins and the 23.4 kDa subunit showed homology to a hypothetical protein of Yersinia pestis and secreted Hcp protein. This protein could induce extensive morphological changes in HEp-2 cells and significant amount of fluid accumulation in rabbit ileal loop. GM1 showed maximum binding to the lectin among all other gangliosides. This purified protein showed cross-reactivity to the binding subunit of cholera toxin in western immunoblot. The presence of this toxin in some of the clinical isolates of enteroaggregative E. coli was also observed. The structural and functional characteristics of the toxin revealed that it is a novel virulence determinant of aggregative E. coli.

Molecular heterogeneity among north Indian isolates of Group A Streptococcus

AIM

To monitor molecular heterogeneity among the clinical isolates of group A Streptococcus (GAS) from north India by Vir and emm typing.

METHODS AND RESULTS

GAS isolates, 31 from pharyngitis and nine from rheumatic fever (RF)/rheumatic heart disease (RHD) patients were differentiated into 16 Vir types (VT). These isolates were further discriminated into 23 emm types. Most of emm types were Vir type specific, except few (7.5%), which revealed different Vir types within same emm type. The most prevalent emm type found was emm 49 (15%) followed by 7.5% of emm 69, emm 71 and emm 75 which were different from emm type distribution reported from south India.

CONCLUSIONS

Analysis of data revealed 40% heterogeneity by Vir typing and 57.5% by emm typing among GAS isolates which is significant in view of small number of isolates studied. SIGNIFICANCE OF IMPACT OF THE STUDY: The molecular study for the first time demonstrates different emm types prevalent and circulating in northern region of India and such data may help in selection of types for vaccine development.

Prevention of tissue injury in an ascending mouse model of chronic pyelonephritis—role of free radical scavengers

The role of free radical scavengers in preventing the tissue injury using a non obstructive, ascending mouse model for chronic pyelonephritis was assessed. The parameters taken into consideration are Luminol Dependent Chemiluminescence (LDCL), histopathology and some biochemical investigations. We have observed that both catalase and Dimethyl-Sulfoxide (DMSO, free radical scavengers) were able to prevent the free radical mediated tissue injury and ultimate renal scarring, irrespective of the bacterial strain studied.

Bilateral environmental and occupational health program with India

In spite of considerable economic progress in recent years, India continues to face challenges dealing with poverty, unemployment, malnutrition, disease and disability. The governments of India and the United States have formed a collaborative effort to address outstanding issues in the fields of environmental and occupational health. The Joint Statement on Indo-U.S. Collaboration in Environmental and Occupational Health, which was approved by the Minister of the Indian Union of Health and Family Welfare and the Secretary of Health and Human Services of the United State in Geneva in May of 2002, formalizes the collaborative relationship and calls for the development of Implementation Guidelines. The Implementation Guidelines establish a Joint Working Group, which is responsible for identifying and implementing the collaborative projects. The collaborating organizations have identified three broad areas for collaboration: emergency preparedness and response; training, education, and technology transfer; and research. Within the three broad areas, the organizations have identified two subject areas for initiation: arsenicosis and asbestosis. Researchers and health officials in both India and the U.S. share interest in both research and interventions efforts in these subject areas. As many as 42 million people in the West Bengal area of India may be exposed to arsenic in drinking water at concentrations of health concern. Similarly, as many as 10 million industrial or mine workers in India may be exposed to asbestos or other dusts at concentrations of health concern. The first Joint Working Group meeting is scheduled for March 2003 in New Delhi and will consider these subject areas in developing collaborative projects. Other tasks being undertaken by the signatory agencies include expanding the relationship to include academic and nongovernmental organizations and obtaining funds for the various projects from governmental and nongovernmental sources.

Outer-membrane-protein subtypes of Haemophilus influenzae isolates from North India

Haemophilus influenzae serotype b and non-typable isolates from blood, cerebrospinal fluid, sputum and throat swabs of patients and carriers in North India were analysed by outer-membrane protein (OMP) profiling. OMP analysis could differentiate the samples into 18 different subtypes. The non-typable isolates were more variable than the serotype b samples. OMP subtypes 1-6 were found only among the serotype b isolates and subtypes 7-18 among the non-typable isolates, while subtypes 2 and 8 were exhibited by both. The OMP profiles of isolates from blood, cerebrospinal fluid and sputum are in complete agreement with their ribotypes and RAPD fingerprints. The present study demonstrates for the first time the subtyping of Indian H. influenzae isolates by an easy and less-expensive method that is applicable to developing countries like India.

Medicine. The need for a global HIV vaccine enterprise

A new collaborative model of research is needed to increase resources, to prioritize the R (ii) to increase the pace, reduce the overlap, and more systematically explore the elements of and delivery systems for vaccines; (iii) to use common standards for the prompt comparative testing of vaccine candidates; (iv) to expand resources for manufacturing vaccine candidates to speed their use in human trials; and (v) to increase the capacity for international clinical trials and to focus this effort toward quickly measuring the effectiveness of vaccine protection as prototype vaccine candidates are identified.

Decreased level of 2,3-diphosphoglycerate and alteration of structural integrity in erythrocytes infected with Plasmodium falciparum in vitro

2,3-Diphosphoglycerate (2,3-DPG), an intracellular metabolite of glycolytic pathway is known to affect the oxygen binding capacity of haemoglobin and mechanical properties of the red blood cells. 2,3-DPG levels have been reported to be elevated during anaemic conditions including visceral leishmaniasis. 2,3-DPG activity in P. falciparum infected red blood cells, particularly in cells infected with different stages of the parasite and its relationship with structural integrity of the cells is not known. Chloroquine sensitive and resistant strains of P. falciparum were cultured in vitro and synchronized cultures of ring, trophozoite and schizont stage rich cells along with the uninfected control erythrocytes were assayed for 2,3-DPG activity and osmotic fragility. It was observed that in both the strains, in infected erythrocytes the 2,3-DPG activity gradually decreased and osmotic fragility gradually increased as the parasite matured from ring to schizont stage. The decrease in 2,3-DPG may probably be due to increased pyruvate kinase activity of parasite origin, which has been shown in erythrocytes infected with several species of Plasmodium. The absence of compensatory increase in 2,3-DPG in P. falciparum infected erythrocytes may aggravate hypoxia due to anaemia in malaria and probably may contribute to hypoxia in cerebral malaria. As 2,3-DPG was not found to be increased in erythrocytes parasitized with P. falciparum, the increased osmotic fragility observed in these cells is not due to increased 2,3-DPG as has been suggested in visceral leishmaniasis.

Influence of Mycobacterium tuberculosis on differential activation of helper T-cells

Host defence against tuberculosis infection involves T-lymphocyte mediated cellular immune responses. In this study we assessed T-cell activation by studying the early signal transduction events and production of cytokines by human CD4+ T-cells. The study constituted of five groups of subjects: (a) untreated acid fast bacilli (AFB)+ve TB patients who have not started anti-tuberculosis therapy (ATT) [New]; (b) patients who have taken ATT for two months [2T]; (c) patients who have taken ATT for six months [6T]; (d) mantoux positive healthy controls [T+ve]; (e) mantoux negative healthy controls [T-ve]. We found that mantoux positive healthy controls produced significantly higher levels of IP3, intracellular Ca2+ and presented increased PKC activity when CD4+ T-cells were stimulated with M. tuberculosis H37Rv cell lysate as compared to mantoux negative controls. Furthermore, decreased expression of CD54 (ICAM-1) and reduced [Ca2+]i were seen in TB patients as compared to T+ve healthy controls. TB patients showed significantly lower levels of IL-2 and IFNgamma and higher levels of IL-4 as compared to normal healthy controls, suggesting a diminished Th1 response. Thus, the reciprocal changes in cytokines, reduced [Ca2+]i levels, and CD54 expression in patients imply phenotype shifting of Th precursors to Th2 type in TB patients.

Evaluation of polymerase chain reaction (PCR) for diagnosing Haemophilus influenzae b meningitis

A polymerase chain reaction (PCR) for detecting Hib in cerebrospinal fluid (CSF) was evaluated and compared with culture and a latex agglutination test (LAT) in a hospital-based prospective surveillance. We studied 107 children aged from 1 month to 12 years with a clinical and CSF profile suggestive of acute bacterial meningitis. CSF culture was performed on blood-chocolate agar by standard technique, LAT by a commercially available kit (Wellcogen) and PCR using total DNA extracted from CSF samples. Of 107 children, 79% had received one or more doses of injectable antibiotics. Hib was detected by culture in 14 cases, by LAT in 23 and by PCR in 37. All CSF samples that reveal Hib by culture or LAT had a PCR positive for Hib (sensitivity 100%). PCR also detected 14 additional cases of Hib meningitis which were not detected by culture or LAT. We conclude that PCR is a sensitive and specific diagnostic tool that may be valuable in a population with high pre-hospital antibiotic usage.

Association of pyrogenic exotoxin genes with pharyngitis and rheumatic fever/rheumatic heart disease among Indian isolates of Streptococcus pyogenes

AIM

To monitor the presence of various pyrogenic exotoxin genes in strains of Streptococcus pyogenes isolated in India.

METHODS & RESULTS

Isolates recovered from pharyngitis (52) and rheumatic fever (RF)/ rheumatic heart disease (RHD) (8) patients were analysed for the presence of toxin genes, speA, speB and speF, by PCR. The specificity of the products was confirmed by restriction enzyme digestion and Southern hybridization. Among the 60 isolates studied, the incidence of speA, speB and speF were 5(8.3%), 56(93.3%) and 53(88.3%), respectively. The expression of these genes was established in representative isolates by RT-PCR.

CONCLUSIONS

Comparative analysis of frequency of the speA, speB and speF genes, among pharyngitis and RF/RHD associated isolates, showed higher incidence in RF/RHD (25%, 100%,100%) as compared to pharyngitis patients (5.8%, 92.3%, 86.5%), respectively. SIGNIFICANCE OF STUDY: The presence of the speA gene, which is usually associated with scarlet fever or toxic shock-like syndrome, within few Indian isolates may be indicative of new virulent strains circulating within the Indian community. High distribution of toxin genes among RF/RHD compared to pharyngitis isolates indicate their possible role in increased virulence.

Priorities in tuberculosis research in India

India accounts for nearly 30% of all tuberculosis cases in the world today and more adults in India die from TB than from any other infectious disease. The problems of HIV and multidrug resistance will make tuberculosis epidemic in India much worse unless urgent action is taken. DOTS is being applied on individual basis in the country. Maintaining the momentum in order to achieve national coverage in a phased manner, while maintaining the quality of services will require constructive commitment from all sectors, both within and outside government. This much be accompanied by additional research inputs and critical data analysis. Operational research provides programme managers the data and tools they need to analyse continuously improve services they offer, hence this must be strengthened with an overall aim to improve diagnosis and treatment of TB patients by translating the results of research into policy and practice. At the same time one should aim to strengthening biomedical research which promises convenient diagnostic tests, new and cost effective drugs and safe an effective vaccines, shortening of treatment, improved treatment of latest infection and overcoming threat of MDR-TB. The challenge is how to achieve this formidable goal as well as gear up to efficiently handle the growing burden of HIV-TB infected patients. The key to success lies in making available to all what we already have, by strengthening operational aspects of programme and at the same time not focus on the research efforts being done in basic science. The solution lies in the link between basic science and public health.

Identification of human hepatocyte protein(s), which binds specifically to the recombinant envelope-2/non-structural-1 protein of hepatitis C virus

Hepatitis C virus (HCV), which is the major pathogen responsible for human chronic liver disease, has special tropism for hepatocytes. Although, low-density lipoprotein receptor, CD81 and negatively charged glycosaminoglycans have been proposed as candidate receptors for HCV, no confirmed receptor(s) on the hepatocytes have been identified to date. It is also suggested that additional, yet unidentified, cellular proteins may be involved in the host-viral interaction. Therefore, this study was conducted with the main aim to identify hepatocyte protein(s) that may have affinity for the HCV structural protein, envelope-2/non-structural-1 (E2/NS1) protein. For the binding studies, hepatocytes were isolated from fresh normal human liver tissues. The hepatocyte proteins on the nitrocellulose paper were reacted with recombinant E2/NS1 protein and anti-E2 (rabbit). In another approach, to rule out the possibility of binding of rec-E2/NS1 with the hepatocyte cytoplasmic proteins, hepatocyte plasma membrane proteins were passed through CNBr-activated and recombinant E2/NS1 bound sepharose-4B column. The recombinant E2/NS1 binding hepatocyte plasma membrane protein(s) were eluted and were then analyzed. Altogether, our data suggest that E2/NS1 protein of HCV binds to two hepatocyte proteins of molecular weights 25-28 kDa and 59-60 kDa. These results indicate the possible role of the above proteins (25-28 kDa and 59-60 kDa) in the viral binding to the hepatocytes.

Effect of vitamin A supplementation on childhood morbidity and mortality

In a double blind design, 1520 children aged < 10 years were individually randomised in vitamin A and placebo group in slums of Chandigarh. Children > 12, 6-12 and < 6 months of age received 200,000, 100,000, 500,000 I.U. of vitamin A respectively every 4 to 6 months during 15 months trial period. The prevalence of vitamin A deficiency was significantly reduced in vitamin A compared to placebo group during the follow-up period. In vitamin A group, incidence of diarrhoea and measles was significantly reduced but incidence of acute respiratory infections was not significantly different compared to control group. Risk of death was also significantly less in vitamin A group. Therefore, promotion of vitamin A rich diet or supplementation with synthetic vitamin A at 4-6 month interval should be a priority in populations where risk of vitamin A deficiency is high.

Expression of sodium-glucose co-transporter and brush border disaccharidases in Giardia lamblia infected rat intestine

The absorption of D-glucose and brush border membrane disaccharidases in the intestine of rat during infection by Giardia lamblia has been studied. The level of mRNA encoding Na+/glucose co-transporter (SGLT1) and brush border sucrase and lactase activities were also analyzed. At the peak of infection, i.e, day 7, 11 and 15 post-infection, there was a marked decrease in the signal of 4.5 kb and 2.8 kb mRNAs encoding SGTL1 compared to the controls. A similar decrease in sucrase and lactase mRNA's (6.5 kb and 6.8 kb respectively) was also observed under these conditions. This corresponds to observed decrease in the rate of Na(+)-dependent D-glucose uptake and low activities of brush border sucrase and lactase under these conditions. There was no change in Na(+)-independent D-glucose uptake in giardia infected rat intestine. These findings suggest that the down regulation of the expression of SGLT1 and brush border sucrase and lactase activities may be responsible for the observed malabsorption in G. lamblia infection.

Subtype distribution of Haemophilus influenzae isolates from north India

A total of 120 Haemophilus influenzae isolates from blood, cerebrospinal fluid, sputum and throat swabs of patients and carriers in North India was characterised by biotyping, ribotyping and random amplification of polymorphic DNA (RAPD)-PCR. Of these, 77 isolates (64%) were serotype b; the other 43 (36%) were non-typable. Biotype I was the most predominant among the typable strains and biotype II among the non-typable strains. Ribotyping with restriction endonucleases HaeIII and EcoRI differentiated the isolates into three and six ribotypes, respectively. However, RAPD fingerprints generated by the application of arbitrary primers AP1 and AP2 provided a higher level of discrimination. RAPD typing revealed distinct polymorphism among the serologically typable isolates. This study is the first report that stratifies the subtypes of H. influenzae strains from India by molecular techniques.

Specific IgA response, T-cell subtype and cytokine profile in experimental intravaginal trichomoniasis

Trichomoniasis caused by Trichomonas vaginalis may lead to either a complete absence of symptoms or to severe inflammatory manifestations in infected women. Studies of the role of immune responses in the pathogenesis and varied symptomatology of this disease are lacking. Mice may prove useful as an experimental model for intravaginal trichomoniasis in developing an understanding of the role of local immune responses in the pathogenesis and varied symptomatology of this disease. The present study reports the levels of anti-Trichomonas IgA antibodies in serum and vaginal washes, and T-cell subtype and cytokine profile in vaginal cervical tissues of mice infected intravaginally with T. vaginalis isolates from 15 symptomatic and 15 asymptomatic women. It also correlates the responses with symptomatology of the patients. Successful intravaginal infection was established by inoculating T. vaginalis in BALB/c mice preinoculated with Lactobacillus acidophilus and pretreated with oestradiol. A significant increase in specific IgA antibody levels was detected with enzyme-linked immunosorbent assay in vaginal secretions and serum samples collected on the 7th post-infection day from animals infected with isolates from asymptomatic women when compared with mice infected with isolates from symptomatic women. T-cell subset analysis showed significant differences, with increased CD4+ T-cell count in animals infected with isolates from asymptomatic women compared with animals infected using isolates from symptomatic women. No difference in CD8+ T cells was observed between the two groups. Cytokine profile revealed significantly higher (P < 0.001) production of gamma-IFN and IL-2 in mice infected with asymptomatic isolates compared with animals infected with symptomatic isolates, using T. vaginalis crude antigen extract and nonspecific mitogen (ConA) as stimulants for vaginal cervical lymphocytes. However, no difference in IL-4 levels was observed in the two groups of animals. In contrast, significant increase in tumour necrosis factor (TNF-alpha) levels was observed in animals infected with asymptomatic isolates compared with those infected with isolates from symptomatic women and controls, thereby indicating that TNF-alpha may play an important role in the inflammatory response to trichomoniasis. The study further suggests that specific IgA antibodies might help to protect asymptomatic individuals from severe infection and T-lymphocytes may play an important function in the eradication of the parasite. The cytokine profile indicated the involvement of Th-1 like responses in mice infected with asymptomatic isolates, compared with those infected with symptomatic isolates.

A community-based rheumatic fever/rheumatic heart disease cohort: twelve-year experience

BACKGROUND

A pilot rheumatic fever and rheumatic heart disease control porject was started in 1988 in blocks of district Ambala (Haryana) to test the feasibility of early detection, treatment and secondary prophylaxis for rheumatic fever/rheumatic heart disease cases. School teachers, students and health workers were trained to identify and refer suspected cases of rheumatic fever/rheumatic heart disease to the community health center where physicians examined the suspected cases and monthly secondary prophylaxis was provided to the confirmed cases.

METHODS AND RESULTS

A survey of registered cases was done in 1999 to determine the compliance rate of secondary prophylaxis and to describe clinical and epidemiologic features of the registered cohort of rheumatic fever/rheumatic heart disease patients. A total of 257 patients had been registered till the end of 1999 with 1263 person-years of follow-up. Out of these registered patients, 132 were receiving secondary prophylaxis, 52 had died, 17 had migrated, 8 were lost to follow-up, 18 had stopped prophylaxis and 30 completed the prophylaxis course. The mean age at registration was 18 years. Half of the cases were in the 6-15 years age group at registration. Over half of the patients were registered with a history of rheumatic fever. Fever was the most common symptom (75.9%). Carditis was more common among cases with recurrent attacks of rheumatic fever than after a first attack. The mortality in rheumatic fever/rheumatic heart cases was 32.5/1000 person-years. The mean age at death was 24.4 years. Compliance with secondary prophylaxis was 92% during the past 12 years.

CONCLUSIONS

A rheumatic fever/rheumatic heart disease control program can be sustained within the primary health care system and the case registry can be utilized not only for monitoring the program but also to gain insight into the epidemiology of the disease.

Detection of antigen B of Cysticercus cellulosae in cerebrospinal fluid for the diagnosis of human neurocysticercosis

Neurocysticercosis (NCC) is a major cause of morbidity and mortality in developed and developing countries. The diagnosis of this disease remains a problem. We report the detection of specific antigenic fraction (antigen B) of Cysticercus cellulosae by enzyme-linked immunosorbent assay (ELISA) in various fractions of cerebrospinal fluid (CSF) obtained by high performance liquid chromatographic (HPLC) separation, for the diagnosis of human NCC. Forty patients attending or admitted to Nehru Hospital, Chandigarh were included in the study: 10 with suspected NCC, 20 with other neurological diseases and 10 undergoing surgery under spinal anaesthesia for non-neurological conditions, who served as controls. CSF samples collected from all patients and controls were subjected to chromatographic separation on an HPLC system. Antigen B (AgB) was detected in separated fractions by an ELISA test and compared with the detection of antibody response in CSF samples by indirect haemagglutination (IHA) technique. Antigen B was detected in 9 out of 10 patients with suspected NCC based on clinical symptoms and radioimaging reports, but in none of the control subjects. However, antigen B was also detected in 9 out of 20 patients with other neurological disorders, mostly tubercular meningitis. Antibody response by IHA was found positive in only 2 of 10 cases clinically suspected of NCC. In conclusion, antigen B detection in CSF samples may be a useful adjunct to clinical suspicion and radiological reports for the diagnosis of NCC as there is no gold standard criteria to confirm this disease. However, the test needs to be evaluated on more patients in countries where tuberculosis and cysticercosis are endemic due to the high cross reactivity with samples from tubercular meningitis patients.

Flow cytometric immunophenotyping and comparison with immunocytochemistry in small round cell tumors

OBJECTIVE

To quantitate different antigens by flow cytometric immunophenotyping (FCI) in small round cell tumors (SRCTs) and to compare the FCI technique with immunocytochemistry (IC).

STUDY DESIGN

IC and FCI were performed on 24 consecutive cases of SRCT on fine needle aspiration biopsy material using a panel of antibodies--e.g., cytokeratin (CK), leukocyte common antigen (LCA), desmin, epithelial membrane antigen, neuron-specific enolase, chromogranin, retinoblastoma gene product, neuroblastoma clone (NB84a (NB), vimentin and Mic-2 gene product. IC was done by indirect immunoperoxidase and FCI by indirect immunofluorescence onflow cytometry.

RESULTS

In Ewing's sarcoma, with the help of FCI, positive results were obtained in an additional 4 samples in CK, 2 samples in actin and 3 samples in desmin. Similarly, one each sample was additional positive regarding Mic-2 and vimentin by IC. In cases of neuroblastoma with the help of FCI, additional positive results were obtained in one each sample of CK, LCA and NB and two in actin. Combined use of FCI and IC helped to show chromogranin positivity in an additional two cases. Divergent differentiation was noted in four cases of Ewing's sarcoma, one neuroblastoma and two peripheral neuroectodermal tumors.

CONCLUSION

FCI technique is sensitive, more objective and quantitative in comparison with manual absorbance-based microscopic detection of enzyme immunohistochemistry products. FCI may determine divergent differentiation in SRCTs.

Inhibition of Helicobacter pylori adherence by a peptide derived from neuraminyl lactose binding adhesin

Helicobacterpylori, like many other gut colonizing bacteria, binds to sialic acid rich macromolecules present on the gastric epithelium. NLBH (neuraminyl lactose binding haemagglutinin) a 32 kDa adhesin located on the surface of H. pylori has been shown to have specific affinity towards NeuAcalpha2,3Galbeta1,4Gluc(3'SL). This sialic acid moiety is over-expressed in an atrophic stomach undergoing parietal cell depletion. Antibodies against a lysine rich peptide fragment of NLBH inhibit agglutination of human erythrocytes. This lysine rich sequence from NLBH was proposed to be the receptor-binding site. In order to elucidate the binding of NLBH to gastric epithelium, a peptide (D-P-K-R-T-I-Q-K-K-S) was synthesized. A series of experiments were performed involving adherence inhibition assays, 2D-NMR, molecular modelling and measurement of modulation in acid secretion. Results indicated that the peptide fragment could be involved in receptor recognition, which is important for the binding of H. pylori to gastric epithelium. The binding is possibly through hydrogen bonding. Two lysines and a threonine residue seem to be within the hydrogen bonding distance of NeuAcalpha2,3Galbeta1,4Gluc. Further, in vitro assays were performed to evaluate the role of the peptide on acid secretion by parietal cells isolated from human fundal biopsies. Interestingly, the peptide increases acid secretion only in H. pylori negative and in treated patients but not in H. pylori positive patients. This highlights the role of NLBH in acid secretion and could be of some consequence in the prognosis of the disease.

Identification and characterization of an excretory-secretory product from Giardia lamblia

A 58 kDa excretory-secretory product (ESP) of Giardia lamblia has been characterized. The ESP was purified over 508-fold by a combination of ammonium sulphate precipitation and sequential chromatography on affinity matrix and a gel filtration column. The homogeneity of the purified protein was established by sodium dodecyl sulphate polyacrylamide gel electrophoresis (Mr, 58 kDa) and analytical isoelectrophoresis (pI 4.75). The purified protein was recognized by the pooled sera of G. lamblia-positive patients as well as an antiserum raised against crude Giardia extract, thus indicating it to be an immunodominant parasite product. The ESP was found to agglutinate rabbit erythrocytes. The haemagglutinating activity of this protein was inhibited strongly by thyroglobulin, fetuin, asialofetuin and monosialoganglioside but not by simple sugars. The purified protein was characterized immunochemically and was found to be heat stable as well as protease sensitive. Lectin-binding studies of the purified ESP and its sensitivity to periodic-acid silver staining as well as to metaperiodate treatment clearly indicated its glycoprotein nature. The major localization site of the ESP was found to be on the surface of the parasite as revealed by flow cytometric analysis. Further, this glycoprotein induced fluid accumulation in ligated rabbit ileal loops and revealed a positive skin permeability reaction in the rabbit.

Human genome project: pharmacogenomics and drug development

Now that all 30,000 or so genes that make up the human genome have been deciphered, pharmaceutical industries are emerging to capitalize the custom based drug treatment. Understanding human genetic variation promises to have a great impact on our ability to uncover the cause of individual variation in response to therapeutics. The study of association between genetics and drug response is called pharmacogenomics. The potential implication of genomics and pharmacogenomics in clinical research and clinical medicine is that disease could be treated according to the interindividual differences in drug disposition and effects, thereby enhancing the drug discovery and providing a stronger scientific basis of each patient's genetic constitution. Sequence information derived from the genomes of many individuals is leading to the rapid discovery of single nucleotide polymorphisms or SNPs. Detection of these human polymorphisms will fuel the discipline of pharmacogenomics by developing more personalized drug therapies. A greater understanding of the way in which individuals with a particular genotype respond to a drug allows manufacturers to identify population subgroups that will benefit most from a particular drug. The increasing emphasis on pharmacogenomics is likely to raise ethical and legal questions regarding, among other things, the design of research studies, the construction of clinical trials and the pricing of drugs.