Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where K.A. Ahmed is active.

Publication


Featured researches published by K.A. Ahmed.


Cell and Tissue Research | 2008

High doses of dietary zinc induce cytokines, chemokines, and apoptosis in reproductive tissues during regression

N.R. Sundaresan; D. Anish; K.V.H. Sastry; V.K. Saxena; K. Nagarajan; J. Subramani; M. D. Marcus Leo; N. Shit; J. Mohan; M. Saxena; K.A. Ahmed

In chickens, high levels of dietary zinc cause molting, and the reproductive system undergoes complete remodeling concomitant to feather replacement. In the present study, the expression profiles of cytokines and chemokines were investigated in the ovary and oviduct of control hens and of hens induced to molt by zinc feeding. The zinc-induced feed-intake suppression, the changes in corticosterone levels, the immune cell populations in the reproductive tract, and the apoptosis of reproductive tissues were analyzed. The expression of mRNAs for interleukin-6 (IL-6), interferon-γ (IFN-γ), the avian ortholog of mammalian IL-8 (chCXCLi2), and a chicken MIP-1β-like chemokine (chCCLi2) in the ovary and of mRNAs for IL-1β, IL-6, IFN-γ, transforming growth factor-β2, chCXCLi2, and chCCLi2 in the oviduct were upregulated significantly during zinc-induced molting. A simultaneous feed-intake reduction was observed with higher expression of cytokines and chemokines. The results of the present investigation also suggested that the upregulation of corticosterone was closely associated with the increased expression of cytokines and chemokines. An increase in apoptosis within reproductive tissue during tissue regression was also noted. We had previously observed the upregulation of these cytokines expression in an earlier study (molting by feed withdrawal). However, the pattern and the level of expression were different among these two methods. These findings indicate that cytokines might be a common mediator of tissue regression during molting induced by diverse methods, although the pattern of induction is different. Thus, a high dose of dietary zinc seems to induce reproductive regression via the upregulation of cytokines and chemokines, the suppression of feed intake, and the increase in serum corticosterone, resulting finally in the apoptosis of reproductive tissues.


International Journal of Immunogenetics | 2007

Immune response to Newcastle disease virus in chicken lines divergently selected for cutaneous hypersensitivity

K.A. Ahmed; V.K. Saxena; A. Ara; K.B. Singh; N.R. Sundaresan; Meeta Saxena; T. J. Rasool

This paper describes for the first time the differential immune response to virulent Newcastle disease virus (NDV) in birds differing in cell‐mediated immunity, as measured by response to phytohaemagglutinin‐P. To explore potential host–pathogen interactions, peripheral blood mononuclear cells (PBMC) were collected from 40 extreme responder birds (20 birds each from high and low cell‐mediated immunity lines). PBMC cultures were stimulated by virulent NDV and temporal expression profiles of interferon‐gamma (IFN‐γ), and inducible nitric oxide synthase (iNOS) mRNA was evaluated by semiquantitative reverse transcription polymerase chain reaction (PCR). To further explore the correlation of iNOS mRNA expression and nitric oxide (NO) production, we assayed the culture supernatants for NO. NO production, as well as iNOS and IFN‐γ mRNA expression, was significantly (P < 0.05) higher in the line with higher cell‐mediated immunity. In our study, a significant (P < 0.05) difference was observed between the lines for IFN‐γ promoter polymorphism for the TspEI site. The high cell‐mediated immunity line mostly revealed the genotype (GG) with a 168‐bp fragment. On the other hand, this genotype was not predominant in the low cell‐mediated immunity line. Later, quantitative real‐time PCR demonstrated higher (P < 0.01) IFN‐γ mRNA transcription in the genotype GG in response to NDV. This difference in promoter region may be responsible for differential IFN‐γ mRNA transcription in chicken lines. Furthermore, birds of high cell‐mediated immunity line showed better adaptive immunity to booster NDV vaccination as revealed by an enhanced antibody titre. Thus, this study provides baseline data on the effect of phytohaemagglutinin‐P response‐based selection on immune responses to virulent NDV and the data could be of immense importance to poultry geneticist and immunologist attempting to breed poultry for disease resistance.


Veterinary Research Communications | 2009

Expression analysis of melatonin receptor subtypes in the ovary of domestic chicken

N.R. Sundaresan; M. D. Marcus Leo; J. Subramani; D. Anish; M. Sudhagar; K.A. Ahmed; M. Saxena; J. S. Tyagi; K.V.H. Sastry; V.K. Saxena

Melatonin (N-acetyl-5-methoxytryptamine), an indole hormone, regulates various biological functions through three different receptor subtypes (Mel-1a, Mel-1b, and Mel-1c). However, the distribution of different melatonin receptor subtypes in chicken reproductive tissues was not known. In the present investigation, the partial sequences of ovarian melatonin receptor subtypes (Mel-1a, Mel-1b, and Mel-1c) were characterized. Further, the expression profile of melatonin receptor subtypes in the granulosa and theca layers of different preovulatory and postovulatory follicles (POF) were studied by semi-quantitative RT-PCR. The expression of all three subtypes of melatonin receptors were observed in the ovary of domestic chicken. Analysis of partial sequences of ovarian melatonin receptors revealed that the melatonin subtypes were identical to the brain receptors. In small white ovary follicles, we observed only the expression of mel-1b receptors, but not mel-1a or mel-1c receptors. In yellow follicles, all the three subtypes of receptors expression were noticed. Interestingly, we observed the expression of mel-1a receptor only in thecal layer, but not in granulosa layer. In contrast, mel-1b and -1c receptors were expressed in both granulosa and thecal layer. During the regression of POF, we observed significant upregulation of melatonin receptors (mel-1a and 1c) expression, that downregulated in the later stages of regression. We assume that the expression of melatonin receptors might have been influenced by the atresia or apoptosis of different follicular layers in POF. Our findings suggest that the differential distribution of melatonin receptor subtypes might have distinct downstream cellular functions in the ovarian tissues.


Veterinary Research Communications | 2008

Caspase-mediated apoptosis in chicken postovulatory follicle regression.

N.R. Sundaresan; V.K. Saxena; K.V.H. Sastry; D. Anish; M. D. Marcus Leo; C. Kantaraja; Meeta Saxena; K.A. Ahmed

Chicken postovulatory follicle (POF) regression occurs via the process of apoptosis. However, the signals and initiator pathways responsible for regression of the POF are unknown. In the current study, we examined gene expression patterns of various caspases (caspase-1, -2 and -3) involved in apoptosis by semi-quantitative RT-PCR. The percentage of apoptotic cells during POF regression was also quantified by flow cytometry. Expression of caspase-3 mRNA was noted in the largest preovulatory follicle (F1). However, the initiator caspases (caspase-1 and -2) were not expressed in F1. During the regression of the POF, caspase-3 was activated during initial stages, whereas the initiator caspases were upregulated at the later stages (POF4 and POF5).The percentage of apoptotic cells was significantly higher during the regression of the POF. It might be possible that levels of caspase-3 mRNA do not necessarily reflect the cell’s potential for facilitating apoptosis, as activation of the caspase-3 by initiator caspases is required for its function. We presume that both caspase-1 and caspase-2 were key initiators in the regression of chicken POF and that the apoptosis-mediated regression of POFs might be similar to mammalian corpus luteum involution.


International Journal of Immunogenetics | 2007

Molecular cloning and sequencing of MHC class II beta 1 domain of turkey reveals high sequence identity with chicken

K.A. Ahmed; V.K. Saxena; M. Saxena; A. Ara; A. B. Pramod; M. L. Rajaram; K. S. Dorman; S. Majumdar; T. J. Rasool

We report the nucleotide sequences of turkey (Meleagris gallopavo) major histocompatibility complex (MHC) class II loci (β 1 domain or exon 2 encoding the peptide‐binding region). In the present investigation, three distinct sequences from the β 1 domain of turkey MHC class II were isolated. A BLAST search and phylogenetic analysis revealed that turkey MHC sequences are most similar to chicken and peacock MHC. There was no strong evidence of recombination among the turkey MHC sequences or with other avian MHC, but diversity was high. The diversity in this peptide‐binding region may be the result of point mutation and balancing selection or frequent gene conversion within turkey. However, more work and data are needed to understand the evolution of turkey and other avian MHC. Moreover, polymerase chain reaction–restriction fragment‐length polymorphism analysis of exon 2 using the Hinf I restriction enzyme demonstrated three restriction patterns and a preliminary evidence of multiple β loci in turkey. PCR‐RFLP analysis of turkey MHC class II loci could be a promising method of MHC genotyping, when more sequences are available. Turkey MHC haplotypes identified earlier by RFLP analysis should be sequenced to standardize turkey MHC nomenclature and to develop DNA based method of haplotyping.


Asian-australasian Journal of Animal Sciences | 2012

Cytokines Expression and Nitric Oxide Production under Induced Infection to Salmonella Typhimurium in Chicken Lines Divergently Selected for Cutaneous Hypersensitivity.

Rani Singh; Preeti Jain; N. K. Pandey; V.K. Saxena; Meeta Saxena; Khushboo Singh; K.A. Ahmed; R. P. Singh

In the present study, the impact of Salmonella Typhimurium on cell-mediated immunity (CMI) was investigated in 5 week-old immuno divergent broiler lines selected for the high and low response to phytohemagglutinin-P. The immune response was assessed in peripheral-blood mononuclear cells (PBMCs) induced with Salmonella Typhimurium at different time intervals (0 h, 0.5 h, 2 h, 4 h, 6 h, 12 h and 24 h). The differential mRNA expression patterns of IFN-γ, IL-2 and iNOS were evaluated by quantitative real time PCR. In-vitro production of nitric oxide (NO) was also estimated in the culture supernatant and correlated with iNOS mRNA expression. Present study showed higher production of NO in the high cell-mediated line (HCMI) as compared to the low cell-mediated line (LCMI) upon stimulation with Salmonella Typhimurium. Correspondingly, higher mRNA expression of iNOS and IFN-γ were observed in high response birds (HCMI); but IL-2 was down regulated in this line compared to the low response birds (LCMI). Significantly (p<0.05) higher expression of iNOS, IFN-γ and higher production of NO in high line indicated that the selection for PHA-P response might be employed for increasing the immune competence against Salmonella Typhimurium in chicken flocks.


Research in Veterinary Science | 2013

In vitro rapid clearance of infectious bursal disease virus in peripheral blood mononuclear cells of chicken lines divergent for antibody response might be related to the enhanced expression of proinflammatory cytokines

Preeti Jain; Rani Singh; V.K. Saxena; K.B. Singh; K.A. Ahmed; Ashok K. Tiwari; Meeta Saxena; N.R. Sundaresan

Abstract Infectious bursal disease (IBD) is an acute and highly contagious viral disease of young chickens caused by infectious bursal disease virus (IBDV). An effective way to control IBDV would be to breed chickens with a reduced susceptibility to IBDV infection. In the present work, we used chickens selected for high and low specific responses to sheep red blood cells (SRBC) (H and L, respectively) to assess the susceptibility of differential immune competent animals to IBDV infection. The peripheral blood mononuclear cells (PBMCs) of high SRBC line (HL) and low SRBC line (LL) were infected with IBDV and viral RNA loads were determined at different time post-IBDV infection. Chicken orthologues of the T helper 1 (Th1) cytokines, interferon-γ (IFN-γ) and interleukin-2 (IL-2); a Th2 cytokine, IL-10; a pro inflammatory cytokine, IL-6; the CCL chemokines, chCCLi2, chCCLi4 and chCCLi7; colony stimulating factor, GM-CSF; and a anti-inflammatory cytokine, transforming growth factor β-2 (TGFβ-2) were quantified. The expression of chCCLi2, chCCLi4 and chCCLi7 was significantly higher in L line as compared to H line. However, in H line the viral RNA loads were significantly lower than in L line. Therefore, the upregulated chemokines might be associated with the susceptibility to IBDV. The expression of IFN-γ, IL-2 and IL-6 was significantly higher in H line as compared to L line. We assume that the higher proinflammatory cytokines expression in H line might be related to the rapid clearance of virus from PBMCs. Significantly higher levels of IL-10 and TGFβ-2 mRNAs in L line might be related to the pathogenesis of IBDV. In conclusion, selection for antibody responses appears to influence the expression profiles of chemokines and cytokines against IBDV. Further, the selection for high SRBC response might improve the immuno-competence of chickens against IBDV.


Veterinary Research Communications | 2008

Spatial expression of chemokines and cytokines mRNA in the largest preovulatory follicle of chicken

N.R. Sundaresan; D. Anish; V.K. Saxena; K.V.H. Sastry; Preeti Jain; Rani Singh; M. Saxena; K.A. Ahmed

In the present experiment, we studied the spatial expression profiles of chemokines and cytokines mRNA in the granulosa (F1Gr) and theca (F1Th) layers of the largest preovulatory follicle in chicken using semi-quantitative PCR. The mRNAs of IL-1β, IL-6, GM-CSF, chCXCLi2, chCCLi2, chCCLi4, chCCLi7, IFN-γ, IL-4, IL-13, IL-10 and TGF-β2 were expressed in the granulosa (F1Gr) and theca (F1Th) layers of the largest preovulatory follicle. However, the transcripts of IL-2 were not detected in any of the samples tested. Significantly higher levels of IL-6 and GM-CSF mRNA expression were noticed in F1Gr when compared to F1Th layer. Expression of chCXCLi2, a CXC chemokine, was almost similar in F1Gr and F1Th layers. However, the expression of CCL chemokines i.e. chCCLi2, chCCLi4, chCCLi7 mRNAs were almost 2 folds higher in F1Th layer in comparison to F1Gr layer. The expression of Th2 cytokines (IL-4 and IL-13) mRNA was noticed in F1Gr and F1Th layers with higher levels in the former. Expression of IFN-γ mRNA was noticed in F1Gr and F1Th layers. Significantly higher level of TGF-β2 expression was observed in F1Th in comparison to F1Gr layer. It was concluded from the present study that the mRNA expression of cytokines and chemokines are differentially regulated in the granulosa and theca layers of the largest preovulatory follicle in chicken.


Journal of Reproductive Immunology | 2007

Cytokines in reproductive remodeling of molting White Leghorn hens

N.R. Sundaresan; D. Anish; K.V.H. Sastry; V.K. Saxena; J. Mohan; K.A. Ahmed


Veterinary Immunology and Immunopathology | 2005

Differential expression of inducible nitric oxide synthase and cytokine mRNA in chicken lines divergent for cutaneous hypersensitivity response

N.R. Sundaresan; K.A. Ahmed; V.K. Saxena; K.V.H. Sastry; Meeta Saxena; A.B. Pramod; M. Nath; K.B. Singh; T. J. Rasool; A.K. DevRoy; Rani Singh

Collaboration


Dive into the K.A. Ahmed's collaboration.

Top Co-Authors

Avatar

V.K. Saxena

Central Avian Research Institute

View shared research outputs
Top Co-Authors

Avatar

N.R. Sundaresan

Indian Veterinary Research Institute

View shared research outputs
Top Co-Authors

Avatar

D. Anish

Indian Veterinary Research Institute

View shared research outputs
Top Co-Authors

Avatar

K.V.H. Sastry

Central Avian Research Institute

View shared research outputs
Top Co-Authors

Avatar

Meeta Saxena

Indian Veterinary Research Institute

View shared research outputs
Top Co-Authors

Avatar

Rani Singh

Central Avian Research Institute

View shared research outputs
Top Co-Authors

Avatar

M. Saxena

Indian Veterinary Research Institute

View shared research outputs
Top Co-Authors

Avatar

Preeti Jain

Central Avian Research Institute

View shared research outputs
Top Co-Authors

Avatar

K. Nagarajan

Indian Veterinary Research Institute

View shared research outputs
Top Co-Authors

Avatar

K.B. Singh

M. J. P. Rohilkhand University

View shared research outputs
Researchain Logo
Decentralizing Knowledge