Biomedical subjects

Sagarika Kanjilal

Publications and source records attributed to Sagarika Kanjilal.

6 recordsLinked to original sources

PubMed2006

Rapid expression of Mycobacterium avium subsp. paratuberculosis recombinant proteins for antigen discovery.

Mycobacterium avium subsp. paratuberculosis is the causative agent of Johne's disease, a chronic granulomatous enteritis of ruminants and other species. Detection of infection in animals is hampered by the lack of sensitive and specific diagnostic assays. We describe here an approach that utilizes translationally active PCR fragments for the rapid in vitro transcription and translation of recombinant proteins for antigen discovery in M. avium subsp. paratuberculosis. The investigations showed that the MAP1272c protein selectively reacts with sera from Johne's disease-positive cattle and represents an antigen of potential utility in M. avium subsp. paratuberculosis immunodiagnostics.

Animals↗

PubMed2006

Somatic alterations of the p53 tumor suppressor gene in vaccine-associated feline sarcoma.

OBJECTIVE: To determine somatic alterations in p53 in vaccine-associated feline sarcoma (VAFS). Animals-27 domestic shorthair cats undergoing first surgical treatment for primary VAFS with no history of chemotherapy or gamma radiation. PROCEDURES: Sequence analysis was performed on the genomic sequence of p53 (between exons 5 through 9) from tumor and blood samples obtained from the cats. Cats were monitored for 3 years and disease-free intervals and survival times calculated. RESULTS: Eight single nucleotide polymorphisms were detected within the genomic sequence of p53, with 20 of 27 cats (74%) having heterozygosity at > or = 1 polymorphic site. Somatic loss of heterozygosity at p53 was detected in the primary tumors of 12 of these 20 (60%) cats. Such allelic deletion was significantly associated with rapid tumor recurrence and reduced overall survival. Point mutations were rare, occurring in 3 of 27 primary tumors. The finding of malignant cells in the surgical margins was significantly associated with disease recurrence, but clear margins (with no detectable malignant cells) were not predictive of positive outcome. CONCLUSIONS AND CLINICAL RELEVANCE: p53 status is an indicator of postsurgical recurrence and overall survival in cats with VAFS. Careful follow-up is important in treating vaccine-site tumors containing allelic deletion of p53, whereas aggressive surgical treatment may be sufficient to control primary vaccination site tumors without the allelic loss.

Animals↗

PubMed2005

The complete genome sequence of Mycobacterium avium subspecies paratuberculosis.

We describe here the complete genome sequence of a common clone of Mycobacterium avium subspecies paratuberculosis (Map) strain K-10, the causative agent of Johne's disease in cattle and other ruminants. The K-10 genome is a single circular chromosome of 4,829,781 base pairs and encodes 4,350 predicted ORFs, 45 tRNAs, and one rRNA operon. In silico analysis identified >3,000 genes with homologs to the human pathogen, M. tuberculosis (Mtb), and 161 unique genomic regions that encode 39 previously unknown Map genes. Analysis of nucleotide substitution rates with Mtb homologs suggest overall strong selection for a vast majority of these shared mycobacterial genes, with only 68 ORFs with a synonymous to nonsynonymous substitution ratio of >2. Comparative sequence analysis reveals several noteworthy features of the K-10 genome including: a relative paucity of the PE/PPE family of sequences that are implicated as virulence factors and known to be immunostimulatory during Mtb infection; truncation in the EntE domain of a salicyl-AMP ligase (MbtA), the first gene in the mycobactin biosynthesis gene cluster, providing a possible explanation for mycobactin dependence of Map; and Map-specific sequences that are likely to serve as potential targets for sensitive and specific molecular and immunologic diagnostic tests. Taken together, the availability of the complete genome sequence offers a foundation for the study of the genetic basis for virulence and physiology in Map and enables the development of new generations of diagnostic tests for bovine Johne's disease.

Animals↗

PubMed2005

Does human sperm nuclear DNA integrity affect embryo quality?

Abnormalities in the male genome are a clear potential reason for post fertilization failure. Male infertility may arise due to high levels of loosely packaged chromatin and damaged DNA. The achievement of a correct chromatin packaging level is essential for successful fertilization. The chromatin contained in the nuclei of mammalian spermatozoa is an extremely compact and stable structure. The reports on mammalian spermatozoa indicate that available volume is insufficient to contain sperm chromatin packed in nucleosome like structure and thus is organized in a special way. Different unique properties of sperm DNA like high degree of inertness and stability, absence of transcription, replacement of somatic histone by protamine etc have made the study of sperm chromatin more interesting. Increased levels of sperm nuclear DNA damage exist in infertile men with abnormal sperm parameters (i.e. concentration, motility and morphology), and various assay techniques have been developed to evaluate sperm chromatin maturity/DNA integrity. These assays are based on the facts that defects in chromatin structure have been shown to lead to increased DNA instability and sensitivity to denaturing stress. DNA integrity in the sperm is essential for the accurate and successful transmission of genetic information. Importance of sperm DNA has also become more obvious in the context of assisted reproductive techniques. While recent advances in assisted reproductive technologies have made possible and practical for many infertile men to become father, the risk of transmission of genetic mutation to the offspring, however, still remains. Further research is necessary to devise techniques for identification and selection of sperm with undamaged DNA for ICSI or to remove sperm with damaged DNA from the semen sample to improve the pregnancy outcome in ICSI.

Animals↗

PubMed2003

Assessment of sperm functional competence and sperm-egg interaction.

A precise understanding in the functional competence of mammalian sperm is essential to generate clinical advances for the treatment of infertility and novel contraceptive strategies. The fundamental knowledge on the controlling parameters for spermatozoal activation process will help in the identifying the causes in fertilization failure due to male factor as well as in developing male contraceptive methodologies. The defects in the sperm-egg interaction seem to be one of the controlling mechanisms, however, none of the presently available methods for the evaluation of the fertilizing ability of sperm precisely indicates the reason for the failure or the success of sperm entry into egg. Adequate number of motile spermatozoa with normal morphology and timely occurrence of acrosome reaction are presumably the major prerequisites for the penetration through the egg investments. The present communication briefly reviews some of the main features of mammalian sperm which control the success or the failure of fertilization and existing clinical methods indicating the lack of fundamental knowledge on the sub-cellular and molecular aspects of this unique and species-specific cell-cell interaction.

Acrosome Reaction↗

PubMed2002

Evaluation of in vitro chemosensitivity of vaccine-associated feline sarcoma cell lines to vincristine and paclitaxel.

OBJECTIVE: To determine the in vitro sensitivity of 4 vaccine-associated feline sarcoma (VAFS) cell lines to the chemotherapeutic agents vincristine and paclitaxel. SAMPLE POPULATION: Cell lines derived from 4 VAFS specimens. PROCEDURES: Cell lines were cultured in vitro and individually exposed to various concentrations of vincristine and paclitaxel. Survival was estimated after 24 and 72 hours of exposure to each drug, and the drug concentrations that resulted in 50 and 90% reduction in number of viable cells (IC50 and IC90, respectively) were calculated. RESULTS: Both vincristine and paclitaxel had significant dose-dependent effects on the viability of the VAFS cell lines. After 72 hours of drug exposure, the IC50 and IC90 of vincristine for the 4 cell lines were between 0.005 to 0.039 microg/ml and 0.045 to 1.027 microg/ml, respectively. The IC50 and IC90 values for paclitaxel were between 0.037 to 0.092 microg/ml and 2.450 to 15.413 microg/ml, respectively. CONCLUSIONS: Results of pharmacokinetic studies on vincristine and paclitaxel in other species suggest that concentrations greater than the IC50 values may be possible for both drugs in feline patients as well. The drug concentrations at which viable cell numbers were reduced by 90% may also be attained in vivo for some cases, but detailed information is needed regarding the distribution, concentration, duration of availability, and toxicity of various drugs in cats. Carefully chosen combinations of antineoplastic agents need to be screened to identify treatment protocols that may be further evaluated clinically for the treatment of VAFS.

Animals↗