Biomedical subjects

N Malla

Publications and source records attributed to N Malla.

At least 19 recordsLinked to original sources

PubMed2006

Nitric oxide radicals in leucocytes and vaginal washes of Trichomonas vaginalis -infected symptomatic and asymptomatic women.

The clinical spectrum of Trichomonas vaginalis infection varies from asymptomatic to mild, moderate or severe vaginitis. Nitric oxide and other reactive nitrogen radicals produced by immune effector cells are important cytotoxic and cytostatic mediators against several microorganisms including parasites. In the present study, inducible nitric oxide synthase (iNOS) and reactive nitrogen intermediates (RNI) were determined in leucocyte cultures (stimulated with T. vaginalis in vitro) and vaginal washes (VWs) of 22 symptomatic and 20 asymptomatic T. vaginalis-infected and 20 healthy women by immunoblotting and Griess method respectively. The iNOS protein was detected in leucocytes and VWs of all the symptomatic and asymptomatic women, but was not detected in any of the samples from healthy women. Mean iNOS protein band intensity was significantly higher in leucocytes as compared to VWs (P<0.001) of both symptomatic and asymptomatic women and was also higher in leucocytes of asymptomatic as compared to symptomatic women (P<0.05). Mean RNI concentration was also significantly higher in leucocytes (P<0.01) and VWs (P<0.05) of asymptomatic as compared to symptomatic women, and was also higher in samples of infected as compared to healthy women (P<0.001). These results suggest that reactive nitrogen radicals may have a role in limiting T. vaginalis infection in asymptomatic women.

Animals↗

PubMed2006

Evaluation of ELISA and dot blots for the serodiagnosis of neurocysticercosis, in children found to have single or multiple enhancing lesions in computerized tomographic scans of the brain.

Although human neurocysticercosis (NCC) is being increasingly recognized in children, diagnosis of the disease can be difficult, and the 'gold standard' criteria that indicate an unambiguous case have still to be established. In the present study, the performances of an ELISA and dot-blot assay, for the detection of antibodies against antigens from larval Taenia solium, were investigated and compared, using sera, from children aged 5-12 years, that were diluted to at least 1:400. Eighty of the subjects (20 aged 5-<8 years and 60 older children) each had the signs and symptoms of NCC, including one brain lesion (N=69) or multiple brain lesions (N=11) that were visible by computed tomography. Another 100 sera, from children who had tubercular meningitis (N=20) or a parasitic disease other than taeniasis/cysticercosis (N=20) or, apart from a minor respiratory-tract infection, appeared healthy (N=60), were also investigated. Most (86%) of the cases of NCC had presented with focal seizures. Analysis of antibody response indicated that the optimum threshold titres for seropositivity were 1:800 for the ELISA and 1:6400 for the dot-blot assays. When used with these thresholds, the ELISA gave a sensitivity, specificity, positive and negative predictive values and diagnostic efficacy of 89%, 81%, 79%, 90%, 85%, respectively. The corresponding values for the dot-blot assay were similar, at 89%, 73%, 72.5%, 89%, 82%, respectively. Both assays were more sensitive, in the detection of the specific antibody response, when used among the paediatric cases of NCC who had multiple brain lesions (100%) than when used among the single-lesion cases (87%). As the ELISA gave higher specificity and diagnostic efficacy than the dot-blot assay, it should be considered the better method for the serological confirmation of NCC in children.

Age Factors↗

PubMed2005

Plasmodium falciparum: polymorphism in the MSP-1 gene in Indian isolates and predominance of certain alleles in cerebral malaria.

Polymorphism in the block-2 region of merozoite surface protein-1 gene in 69 North Indian Plasmodium falciparum isolates was studied by PCR and RFLP using Dra-1 endonuclease. On the basis of molecular weight of the PCR products, considerable size polymorphism in target gene was seen and 69 isolates were classified into five allelic types. On RFLP, the isolates in three allelic types were further divided into two sub-allelic types each and thus eight genetic types could be identified. Interestingly, all five allelic types were identified in 47 isolates from uncomplicated (non-cerebral) malaria patients while only two allelic types (Type 2 and 3) were seen amongst 22 isolates from cerebral malaria patients. Furthermore, on RFLP, one subtype (2A) was predominantly seen in cerebral malaria patients and one subtype (3A) was exclusively found in cerebral malaria patients. These observations suggest that a few, comparatively more virulent isolates prevalent in an area may cause severe disease (cerebral malaria) which can be identified by molecular techniques like PCR-RFLP.

Adolescent↗

PubMed2005

Antigenaemia and antibody response to Toxoplasma gondii in human immunodeficiency virus-infected patients.

Toxoplasma encephalitis in immunocompromised patients results from reactivation of previously acquired (latent) infection. The aim of the study is to assess the antigenaemia and antibody response to Toxoplasma gondii in human immunodeficiency virus (HIV)-infected patients to determine the best marker for early diagnosis of toxoplasmosis in such patients. Indirect enzyme-linked immunosorbent assay (ELISA) for detection of IgG, IgM and IgA anti-toxoplasma antibodies and double-sandwich ELISA for toxoplasma antigen is carried out in serum samples collected from 100 HIV seropositive patients and 75 controls. Toxoplasma-specific IgG, IgM and IgA antibody response and antigenaemia were detected in 12%, 6%, 7% and 14% of HIV-infected patients, respectively. On retrospective analysis of 14 patients with antigenaemia only one had central nervous system (CNS) symptoms attributable to toxoplasma infection. In this patient, the CD4+ cell count was below 50/microL and none of the specific immunoglobulin isotype responses could be detected. The patient showed clinical improvement following specific chemotherapy for toxoplasmosis. In 25 HIV-negative and anti-toxoplasma IgG antibody-positive controls, IgM was detected in two (8%), IgA in five (20%) and antigenaemia in 10 (40%), while 50 HIV seronegative healthy controls were negative for both antigen and antibody responses. The study indicates that detection of toxoplasma antigen in addition to IgG antibody response may prove to be a useful indicator in the early diagnosis of reactivated toxoplasmosis in HIV/AIDS patients.

Acquired Immunodeficiency Syndrome↗

PubMed2005

Antibody response to Toxoplasma gondii in saliva samples from human immunodeficiency virus-infected patients.

Toxoplasma gondii is an important opportunistic infection among human immunodeficiency virus (HIV)-infected patients as it causes fatal encephalitis. In the present study, antibody response to T. gondii is assessed in saliva samples from 100 HIV-seropositive patients and 25 HIV-negative healthy controls by indirect enzyme-linked immunosorbent assay (ELISA). Sensitivity and specificity for detection of IgG and IgM in saliva is calculated using a positive antibody response in serum samples (from an earlier study) as the gold standard. IgG and IgM antibodies were found in 20% and 25% patients, respectively. One control subject showed the presence of IgM antibody. Sensitivity for IgG and IgM antibodies was 64% and 81.25%, respectively, while specificity was 94.67% and 85.71%, respectively. This study indicates that saliva samples can be used as an alternative to serum samples to detect anti-toxoplasma antibodies, particularly IgM, for the diagnosis of toxoplasma encephalitis in HIV/acquired immune deficiency syndrome patients.

AIDS-Related Opportunistic Infections↗

PubMed2005

Kinetics of immunoglobulin G, M, A and IgG subclass responses in experimental intravaginal trichomoniasis: prominence of IgG1 response.

Trichomoniasis, the most common nonviral sexually transmitted disease, is caused by infection with the protist Trichomonas vaginalis. The clinical spectrum varies from an asymptomatic state to mild, moderate or severe symptoms. However, the exact factors leading to varied symptomatology have not been well elucidated. The mouse is a useful experimental model for intravaginal trichomoniasis, for understanding the role of local immune responses in the pathogenesis and varied symptomatology of this disease. The present study reports anti-Trichomonas IgG, IgM, IgA and IgG subclass antibody responses on different post-infection days (3rd, 7th, 14th, 21st and 28th) in serum and vaginal washes of mice infected intravaginally with T. vaginalis isolates from 15 symptomatic and 15 asymptomatic women. Successful intravaginal infection was established by inoculating T. vaginalis in BALB/c mice pre-inoculated with Lactobacillus acidophilus and pretreated with oestradiol. A significant increase in parasite load was observed on the 14th post-infection day (p.i.d.) in mice inoculated with T. vaginalis isolates from symptomatic women as compared to asymptomatic women (P < 0.001), followed by reduction until the 28th p.i.d. (P < 0.05). A significant increase in specific IgG (P < 0.001) and in particular IgG1 (P < 0.001) and IgM (P < 0.01) responses was observed on the 14th p.i.d. in serum and vaginal washes of mice infected with T. vaginalis isolates from symptomatic women as compared to asymptomatic women. Significant increases in specific IgG, IgM and IgG1 responses was observed on the 14th p.i.d. in serum samples as compared with vaginal washes of mice infected with T. vaginalis isolates from symptomatic and asymptomatic women (P < 0.01), whereas no significant difference was observed in IgA, IgG2a, IgG2b and IgG3 antibody responses. The study indicates that specific IgG, particularly IgG1 and IgM, may be playing a role in establishing symptomatic infection.

Animals↗

PubMed2005

Association of parasitic infections and cancers.

Recent advances in the fields of molecular biology, epidemiology and infectious diseases have led to significant revelations to clarify the relationship between cancer and infective agents. This article reviews the relationship between parasitic infections and carcinogenesis and the possible mechanisms involved. Few parasites, e.g., Schistosoma haematobium and Opisthorchis viverrini have been found to be strongly associated with bladder cancer and cholangiocarcinoma respectively. The evidence for the association of several other parasites and cancers has also been postulated.

Animals↗

PubMed2005

Genetic polymorphism in Plasmodium falciparum vaccine candidate antigens.

Malaria is still a major public health problem in many tropical and subtropical countries. Malaria vaccine is highly desirable as an adjunct to existing malaria control measures. The polymorphisms in malaria vaccine candidates antigens might be a hurdle in developing an effective vaccine. The present article reviews the genetic polymorphism in several antigens expressed on the parasite surface, which are targets for immunological responses of the host and are good candidates for vaccine development against P. falciparum. Variable regions of most genes are generally dimorphic probably as a result of intragenic recombinations. Each allele in turn shows polymorphism resulting from point mutations, or other mechanisms. Several antigens like merozoite surface protein-1 and 2 (MSP-1 and MSP-2) and S antigen show high polymorphism while in others like circumsporozoite protein (CSP), apical membrane antigen-1 (AMA-1) and erythrocyte binding antigen-175 (EBA-175) functional constraints limit the degree of polymorphism. Polymorphism reported in these genes is discussed.

Animals↗

PubMed2004

Intestinal cryptosporidiasis in living related renal transplant recipients.

Cryptosporidium infestations are common in immunocompromised AIDS patients. However, the literature in renal transplant recipients is scarce. We conducted a study to know the prevalence, disease manifestations, and management of cryptosporidial infestations in live related renal transplant recipients. Cryptosporidial infestations were observed in 20% of patients, including 16.6% who had symptomatic diarrhea. We conclude that the prevalence is high in the transplant population, but only a few patients are symptomatic. Clinicians should routinely request special stains to demonstrate cryptosporidium in stool specimens.

Adult↗

PubMed2003

Antigenaemia and antibody response to Leishmania donovani stage-specific antigens and rk39 antigen in human immunodeficiency virus-infected patients.

In order to define the possible markers for the early diagnosis of asymptomatic visceral leishmaniasis in human immunodeficiency virus (HIV)-infected individuals, the antigenaemia and antibody response to stage-specific Leishmania donovani and rk39 antigens is assessed by enzyme-linked immunosorbent assay (ELISA) and immunoreactivity to stage-specific antigens analysed by Western blot. Serum samples from two out of 100 HIV-infected individuals were found positive for antigenaemia, antibody response to stage-specific L. donovani antigens and rk39 antigen, and one sample was also positive for antigenaemia and antibody response to L. donovani antigens, while antibody detection to rk39 antigen was not carried on this sample. Additionally, one sample was found positive for amastigote antigenaemia and antibody response to amastigote antigen, while in this patient promastigote antigenaemia and antibody response to promastigote L. donovani and rk39 antigen could not be detected. One sample was found positive for antigenaemia, antibody response to amastigote antigen and negative for antibody response to promastigote antigen, while in this patient response to rk39 antigen was borderline. Although antibody response to rk39 antigen could be detected in 9/88 (10%) HIV-infected individuals, in six of these nine patients neither antigenaemia nor antibody response to stage-specific L. donovani antigens could be detected. All 10 confirmed visceral leishmaniasis and HIV-negative control patients had positive antigenaemia and antibody response to L. donovani amastigote and promastigote antigens, while all the normal healthy individuals were negative. The study indicated that detection of antibody response to rk39 antigen, amastigote antigenaemia and antibody response to amastigote antigen may prove to be better markers than detection of promastigote antigenaemia, antibody response to promastigote antigen and immunoblot reactivity.

AIDS-Related Opportunistic Infections↗

PubMed2002

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.

Animals↗

PubMed2001

Ca2+ signaling in the transformation of promastigotes to axenic amastigotes of Leishmania donovani.

The present study is an attempt to look into the role of Ca2+ in signaling the transformation of promastigotes to axenic amastigotes. An estimation of intracellular free calcium concentration at 6 h intervals during the conversion of promastigotes to axenic amastigotes (72 h) revealed a 10 fold increase in [Ca2+]i at the initial 6-12 h during the conversion. This was followed by declining levels till 60 h and the concentration thereafter remained constant. Axenic amastigotes (72 h) had a 5 fold higher [Ca+]i as compared to the promastigotes. A 30-40% decrease in [Ca2+]i after pretreatment of cells with dentrolene and a gradual rise of intracellular Ca2+ in [Ca2+] free medium indicates the role of intracellular calcium pools in the elevation of [Ca2+]i. A sudden increase in [Ca2+]i on addition of NH4Cl (20 mM) in the cells grown in Ca2+ free medium indicates the presence of acidocalcisomes, as intracellular Ca2+ storing pool, in L. donovani. To study the role of Ca2+ influx from the external medium in the morphogenetic transformation and in the elevation of [Ca2+]i a 45Ca2+ uptake study was performed. Maximum uptake of 45Ca2+ was observed in the initial 24 h of transformation and maximum Ca2+ ATPase activity was also observed between 24-42 h. So the presence of low Ca2+ in the cytosol, existence of intracellular Ca2+ pools and presence of mechanisms to maintain the Ca2+ homeostasis in the cells suggests that Ca2+ can be an appropriate candidate for a second messenger during the morphogenetic transformation of L. donovani.

Ammonium Chloride↗

PubMed2000

Cellular immune responses in human neurocysticercosis.

Studies on the role of cell-mediated immune responses in human neurocysticercosis (NCC) are lacking. Various cell-mediated immune responses such as lymphocyte subpopulation, lymphocyte transformation to cysticercus antigens and cytokine profile were carried out in NCC patients. Lymphocyte transformation assays using larval antigens showed significantly higher (3)H-thymidine uptake. Immunophenotyping analysis showed an insignificant increase in B cells and a decrease in total T cells. However, there was a significant decrease (P < 0.05) in CD8+ T cells whereas there was no change in other cells like CD4+, HLA-DR+ and CD16+/CD56+. Cytokine profile revealed significantly higher (P < 0.01) production of Th1 cytokines (gamma-IFN and IL-2) using cysticercal antigens as stimulants for peripheral blood mononuclear cells, while there was no difference in IL-4 levels between NCC patients and healthy controls. The cytokine profile indicated the involvement of Th-1-like responses in NCC patients.

Antigens, Helminth↗

PubMed2000

Isolation of emetine resistant clones of Entamoeba histolytica by petri dish agar method.

Emetine resistant clones of Entamoeba histolytica strain HM1:IMSS were isolated by using petri dish agar method after mutation with ethyl-methanesulphonate. Two emetine resistant clones were obtained and both were resistant to emetine at a concentration of 24 micrograms/ml of emetine. The 50 per cent inhibitory concentration (IC50) for both emetine sensitive and resistant clones was 5 and 14 micrograms/ml respectively. The colony forming efficiency of E. histolytica strain HM1:IMSS varied from 44 to 54 per cent. This method is useful for isolating clones from different strains of the parasite for molecular and immunological studies.

Agar↗

PubMed2000

Kinetics of humoral & cellular immune responses in experimental cysticercosis in pigs infected with Taenia solium.

Studies were undertaken to assess the kinetics of antibody responses, lymphocyte transformation to Taenia solium larval antigens (crude soluble extract antigen and antigen B), and T cell subpopulation in piglets following experimental infection. Cysticercosis was established in 1-2 month old piglets after feeding 5,00,000 T. solium eggs per pig. The anti-CD4 and anti-CD8 monoclonal antibodies against swine T cells were raised indigenously. It was observed that at 60 days post infection (PI) there was a significant increase (P < 0.01) in CD4+ T cells without any change in CD8+ T cells. Increased 3H-thymidine uptake was found in infected piglets at 45 days PI using both CSE and antigen B. Kinetics of antibody responses indicated significant increase (P < 0.01) at 15 days PI (with CSE antigen) and 30 days PI (with antigen B) by ELISA. This increase persisted till 90 days PI (the time up to which the animals were followed). It was also observed that the cellular mechanisms were triggered in late stage (60 days PI) as compared to humoral responses (15-30 days PI) and may persist longer as seen by both lymphocyte transformation and T cell subpopulation studies. The study suggests that in cysticercosis, both humoral and cellular mechanisms may play a role in the host defences.

Animals↗

PubMed2000

Fasciolopslasis--a re-emerging infection in Azamgarh (Uttar Pradesh).

Fasciolopsiasis is endemic in the far east. In India, there have been a few reports of the infection, prior to the 1990's. We report two cases from Azamgarh district of Uttar Pradesh. Both the cases were from nearby villages where water chestnuts are cultivated. These may be a source of infection. Pigs are commonly observed in these areas and and may be the source of ova. The only missing link is the finding of infected snails. Presence of at least three cases (one reported earlier) in the area indicates the potential for the infection to re-emerge. Further epidemiological studies are needed to analyse the various ecological factors of transmission. Fasciolopsiasis is endemic in China, Taiwan, Vietnam and Thailand. In India, (Fascilopsis buski) infections in man have been reported earlier from Assam, Maharashtra, Tamil Nadu and parts of Uttar Pradesh. However, to the best of our knowledge, no such reports have been made since 1990's. We herewith report two recent cases from district Azamgarh, Uttar Pradesh (U.P.), India. Factors, such as cultivation of water chestnuts, presence of snails as intermediate hosts and pigs as definitive host in this geographical area seem to be suggestive of an endemic focus and thus needs further epidemiological survey for preventive and control measures, at the earliest.

Adult↗

PubMed1999

Diagnostic accuracy of rapid enzyme linked immunosorbent assay for the diagnosis of human hydatidosis.

Rapid enzyme linked immunosorbent assay (ELISA) was compared with the standard ELISA and indirect haemagglutination (IHA) techniques for the diagnosis of human hydatidosis. Eighty nine serum samples including 17 from hydatidosis patients (10 surgically confirmed and 7 clinically suspected), 50 from patients with other parasitic diseases and 22 samples from normal healthy individuals were analysed for anti-hydatid IgG antibodies using sheep hydatid cyst fluid antigen. The sensitivity and specificity respectively was found to be 82.3 and 100 per cent by rapid ELISA; 88.23 and 90.27 per cent by standard ELISA and 70.58 and 100 per cent by IHA technique. No cross reactions were observed with rapid ELISA technique using samples from cysticercosis and amoebiasis patients and normal healthy controls. The present study indicates that rapid ELISA can easily be performed in place of the standard ELISA for the serodiagnosis of human hydatidosis with the advantage of minimising reporting time and manpower hours.

Antibodies, Helminth↗

PubMed1996

Microbicidal mechanisms of liver macrophages in experimental visceral leishmaniasis.

To study the differential microbicidal potentials of liver macrophages, the oxygen-dependent and oxygen-independent pathways in Kupffer cells and immigrant macrophages of Leishmania donovani-infected BALB/c mice were investigated. Hydrogen peroxide assay was performed using horse radish peroxidase-dependent oxidation of phenol red to quantitate the reactive oxygen species produced. To examine the oxygen-independent pathway, the enzymes N-acetyl-beta-glucosaminidase (NAG) and beta-glucuronidase (beta G) were investigated after exposure of cells to lipopolysaccharide. Hydrogen peroxide release by Kupffer cells was significantly decreased only at 21 days postinfection, whereas hydrogen peroxide release by immigrant macrophages was significantly increased on all postinfection days with a maximum at 21 days postinfection. The pattern of release of NAG and beta G was similar in both cell populations with a peak at 21 days postinfection. The present study therefore suggests that Kupffer cells and immigrant macrophages adopt different pathways to cope with this infection.

Acetylglucosaminidase↗