Dr. J. Vijayalakshmi, Dept. of Human Genetics, SRU (original) (raw)
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Teaching Documents by Dr. J. Vijayalakshmi, Dept. of Human Genetics, SRU
HELIYON , 2023
In the modern developing society, application of radiation has increased extensively. With signif... more In the modern developing society, application of radiation has increased extensively. With significant improvement in the radiation protection practices, exposure to human could be minimized substantially, but cannot be avoided completely. Assessment of exposure is essential for
regulatory decision and medical management as applicable. Until now, cytogenetic changes have
served as surrogate marker of radiation exposure and have been extensively employed for biological dose estimation of various planned and unplanned exposures. Dicentric Chromosomal
Aberration (DCA) is radiation specific and is considered as gold standard, micronucleus is not
very specific to radiation and is considered as an alternative method for biodosimetry. In this
study dose response curves were generated for X-ray induced “dicentric + ring” and micronuclei,
in lymphocytes of three healthy volunteers [2 females (age 22, 23 years) and 1 male (24 year)].
The blood samples were irradiated with X-ray using LINAC (energy 6 MV, dose rate 6 Gy/min), in
the dose range of 0–5Gy. Irradiated blood samples were cultured and processed to harvest
metaphases, as per standard procedures recommended by International Atomic Energy Agency.
Pooled data obtained from all the three volunteers, were in agreement with Poisson distribution
for “dicentric + ring”, however over dispersion was observed for micronuclei. Data (“dicentric +
ring” and micronuclei) were fitted by linear quadratic model of the expression Y– –C + αD + βD2
using Dose Estimate software, version 5.2. The data fit has resulted in linear coefficient α =
0.0006 (±0.0068) “dicentric + ring” cell− 1 Gy− 1 and quadratic coefficient β = 0.0619 (±0.0043)
“dicentric + ring” cell− 1 Gy− 2 for “dicentric + ring” and linear coefficient α = 0.0459 ± (0.0038)
micronuclei cell− 1 Gy− 1 and quadratic coefficient β = 0.0185 ± (0.0010) micronuclei cell− 1 Gy− 2
for micronuclei, respectively. Background frequencies for “dicentric + ring” and micronuclei were
0.0006 ± 0.0004 and 0.0077 ± 0.0012 cell− 1, respectively. Established curves were validated, by
reconstructing the doses of 8 dose blinded samples (4 by DCA and 4 by CBMN) using coefficients generated here. Estimated doses were within the variation of 0.9–16% for “dicentric + ring” and
21.7–31.2% for micronuclei respectively. These established curves have potential to be employed
for biodosimetry of occupational, clinical and accidental exposures, for initial triage and medical
management.
Papers by Dr. J. Vijayalakshmi, Dept. of Human Genetics, SRU
Heliyon
In the modern developing society, application of radiation has increased extensively. With signif... more In the modern developing society, application of radiation has increased extensively. With significant improvement in the radiation protection practices, exposure to human could be minimized substantially, but cannot be avoided completely. Assessment of exposure is essential for regulatory decision and medical management as applicable. Until now, cytogenetic changes have served as surrogate marker of radiation exposure and have been extensively employed for biological dose estimation of various planned and unplanned exposures. Dicentric Chromosomal Aberration (DCA) is radiation specific and is considered as gold standard, micronucleus is not very specific to radiation and is considered as an alternative method for biodosimetry. In this study dose response curves were generated for X-ray induced “dicentric + ring” and micronuclei, in lymphocytes of three healthy volunteers [2 females (age 22, 23 years) and 1 male (24 year)]. The blood samples were irradiated with X-ray using LINAC (energy 6 MV, dose rate 6 Gy/min), in the dose range of 0–5Gy. Irradiated blood samples were cultured and processed to harvest metaphases, as per standard procedures recommended by International Atomic Energy Agency. Pooled data obtained from all the three volunteers, were in agreement with Poisson distribution for “dicentric + ring”, however over dispersion was observed for micronuclei. Data (“dicentric + ring” and micronuclei) were fitted by linear quadratic model of the expression Y– –C + αD + βD2 using Dose Estimate software, version 5.2. The data fit has resulted in linear coefficient α = 0.0006 (±0.0068) “dicentric + ring” cell− 1 Gy− 1 and quadratic coefficient β = 0.0619 (±0.0043) “dicentric + ring” cell− 1 Gy− 2 for “dicentric + ring” and linear coefficient α = 0.0459 ± (0.0038) micronuclei cell− 1 Gy− 1 and quadratic coefficient β = 0.0185 ± (0.0010) micronuclei cell− 1 Gy− 2 for micronuclei, respectively. Background frequencies for “dicentric + ring” and micronuclei were 0.0006 ± 0.0004 and 0.0077 ± 0.0012 cell− 1, respectively. Established curves were validated, by reconstructing the doses of 8 dose blinded samples (4 by DCA and 4 by CBMN) using coefficients generated here. Estimated doses were within the variation of 0.9–16% for “dicentric + ring” and 21.7–31.2% for micronuclei respectively. These established curves have potential to be employed for biodosimetry of occupational, clinical and accidental exposures, for initial triage and medical management.
INTERNATIONAL JOURNAL OF HUMAN GENETICS, 2013
Considerable progress has been made to study the pathophysiology of male infertility in the last ... more Considerable progress has been made to study the pathophysiology of male infertility in the last few years. About 10-15% of genetic causes such as chromosomal abnormality, single gene and multifactorial mutations may be a causative factor. Submicroscopic microdeletions on chromosome Y is considered to be the most frequent genetic defects associated with impaired spermatogenesis. Therefore, the aim of this present study was to assess pregnancy outcome of intracytoplasmic sperm injection (ICSI) in infertile men from 285 study subjects; fertile controls (n=110) and cases (n=175) with sperm count less than 5 millions/ml [azoospermia (n=150) and oligoasthenoteratozoospermia (n=25)]. Microdeletions located on chromosome Y-sY84, sY86 (AZFa), sY127, sY134 (AZFb), and sY254, sY255 (AZFc) were confirmed with Polymerase Chain Reaction (PCR). A 12.56% was observed in infertile men in one or more STS with a percentage of 1.14, 2.28, 9.14 for AZFa, b and c respectively. The azoospermia factor region c (AZFc) loci showed an increase in frequency when compared to AZFb and a regions. Intracytoplasmic Sperm Injection (ICSI) could be offered or an alternative method to patients with AZFc deletion.
Cytometry Part A, 2015
Measurement of γ‐H2AX protein changes in the peripheral blood lymphocytes (PBL) of individuals ex... more Measurement of γ‐H2AX protein changes in the peripheral blood lymphocytes (PBL) of individuals exposed to ionizing radiation is a simple, sensitive, and rapid assay for radiation triage and early marker of dose estimation. The qualitative and quantitative measurements of the protein changes were examined using flow cytometry and microscopy. Whole blood and isolated lymphocytes were exposed in vitro between 0.1 and 5 Gy doses of 60Co γ‐radiation at a dose rate of 1 Gy/min. Radiation induced γ‐H2AX foci frequency (n = 3) and relative fluorescence intensity (n = 7) in PBL was measured at 0.5 and 2 hrs postexposure. The observed dose response for γ‐H2AX foci frequency at both time points, for whole blood and isolated lymphocytes did not show any significant (P > 0.05) differences. However, when compared with γ‐H2AX foci frequency scored manually (microscopy), the semiautomated analysis (captured images) showed a better correlation (r2 = 0.918) than that obtained with automated (Metaf...
Dose-response : a publication of International Hormesis Society, 2014
While contradictory reports are available on the yield of dicentric chromosomes (DC) in blood sam... more While contradictory reports are available on the yield of dicentric chromosomes (DC) in blood samples stored at different temperature and stimulated to enter into cell cycle, various times gap followed by exposure, limited information is available on the micronucleus (MN) assay. As scoring the micronuclei frequency from the blood lymphocytes of exposed individuals is an alternative to the gold standard DC assay for triage applications, we examined radiation induced MN yield in delayed mitogenic stimulation after irradiation of in vitro. Peripheral blood lymphocytes (PBL) were exposed to low LET ((60)Co) radiation dose (0.1 to 5Gy) and incubated at 37°C for 2, 6 and 24 hours. The MN frequency obtained in blood samples stimulated 2 hours post-irradiation showed a dose dependent increase and used to construct the dose-response curve. Further, the results also showed that blood samples stimulated twenty four hours of post-irradiation, a significant reduction (p<0.05) in MN frequencie...
Applied radiation and isotopes : including data, instrumentation and methods for use in agriculture, industry and medicine, 2014
To facilitate efficient handling of large samples, an attempt towards networking of laboratories ... more To facilitate efficient handling of large samples, an attempt towards networking of laboratories in India for biological dosimetry was carried out. Human peripheral blood samples were exposed to (60)Co γ-radiation for ten different doses (0-5Gy) at a dose rate of 0.7 and 2Gy/min. The chromosomal aberrations (CA) were scored in Giemsa-stained and fluorescence in-situ hybridization with centromere-specific probes. No significant difference (p>0.05) was observed in the CA yield for given doses except 4 and 5Gy, between the laboratories, among the scorers and also staining methods adapted suggest the reliability and validates the inter-lab comparisons exercise for triage applications.
HELIYON , 2023
In the modern developing society, application of radiation has increased extensively. With signif... more In the modern developing society, application of radiation has increased extensively. With significant improvement in the radiation protection practices, exposure to human could be minimized substantially, but cannot be avoided completely. Assessment of exposure is essential for
regulatory decision and medical management as applicable. Until now, cytogenetic changes have
served as surrogate marker of radiation exposure and have been extensively employed for biological dose estimation of various planned and unplanned exposures. Dicentric Chromosomal
Aberration (DCA) is radiation specific and is considered as gold standard, micronucleus is not
very specific to radiation and is considered as an alternative method for biodosimetry. In this
study dose response curves were generated for X-ray induced “dicentric + ring” and micronuclei,
in lymphocytes of three healthy volunteers [2 females (age 22, 23 years) and 1 male (24 year)].
The blood samples were irradiated with X-ray using LINAC (energy 6 MV, dose rate 6 Gy/min), in
the dose range of 0–5Gy. Irradiated blood samples were cultured and processed to harvest
metaphases, as per standard procedures recommended by International Atomic Energy Agency.
Pooled data obtained from all the three volunteers, were in agreement with Poisson distribution
for “dicentric + ring”, however over dispersion was observed for micronuclei. Data (“dicentric +
ring” and micronuclei) were fitted by linear quadratic model of the expression Y– –C + αD + βD2
using Dose Estimate software, version 5.2. The data fit has resulted in linear coefficient α =
0.0006 (±0.0068) “dicentric + ring” cell− 1 Gy− 1 and quadratic coefficient β = 0.0619 (±0.0043)
“dicentric + ring” cell− 1 Gy− 2 for “dicentric + ring” and linear coefficient α = 0.0459 ± (0.0038)
micronuclei cell− 1 Gy− 1 and quadratic coefficient β = 0.0185 ± (0.0010) micronuclei cell− 1 Gy− 2
for micronuclei, respectively. Background frequencies for “dicentric + ring” and micronuclei were
0.0006 ± 0.0004 and 0.0077 ± 0.0012 cell− 1, respectively. Established curves were validated, by
reconstructing the doses of 8 dose blinded samples (4 by DCA and 4 by CBMN) using coefficients generated here. Estimated doses were within the variation of 0.9–16% for “dicentric + ring” and
21.7–31.2% for micronuclei respectively. These established curves have potential to be employed
for biodosimetry of occupational, clinical and accidental exposures, for initial triage and medical
management.
Heliyon
In the modern developing society, application of radiation has increased extensively. With signif... more In the modern developing society, application of radiation has increased extensively. With significant improvement in the radiation protection practices, exposure to human could be minimized substantially, but cannot be avoided completely. Assessment of exposure is essential for regulatory decision and medical management as applicable. Until now, cytogenetic changes have served as surrogate marker of radiation exposure and have been extensively employed for biological dose estimation of various planned and unplanned exposures. Dicentric Chromosomal Aberration (DCA) is radiation specific and is considered as gold standard, micronucleus is not very specific to radiation and is considered as an alternative method for biodosimetry. In this study dose response curves were generated for X-ray induced “dicentric + ring” and micronuclei, in lymphocytes of three healthy volunteers [2 females (age 22, 23 years) and 1 male (24 year)]. The blood samples were irradiated with X-ray using LINAC (energy 6 MV, dose rate 6 Gy/min), in the dose range of 0–5Gy. Irradiated blood samples were cultured and processed to harvest metaphases, as per standard procedures recommended by International Atomic Energy Agency. Pooled data obtained from all the three volunteers, were in agreement with Poisson distribution for “dicentric + ring”, however over dispersion was observed for micronuclei. Data (“dicentric + ring” and micronuclei) were fitted by linear quadratic model of the expression Y– –C + αD + βD2 using Dose Estimate software, version 5.2. The data fit has resulted in linear coefficient α = 0.0006 (±0.0068) “dicentric + ring” cell− 1 Gy− 1 and quadratic coefficient β = 0.0619 (±0.0043) “dicentric + ring” cell− 1 Gy− 2 for “dicentric + ring” and linear coefficient α = 0.0459 ± (0.0038) micronuclei cell− 1 Gy− 1 and quadratic coefficient β = 0.0185 ± (0.0010) micronuclei cell− 1 Gy− 2 for micronuclei, respectively. Background frequencies for “dicentric + ring” and micronuclei were 0.0006 ± 0.0004 and 0.0077 ± 0.0012 cell− 1, respectively. Established curves were validated, by reconstructing the doses of 8 dose blinded samples (4 by DCA and 4 by CBMN) using coefficients generated here. Estimated doses were within the variation of 0.9–16% for “dicentric + ring” and 21.7–31.2% for micronuclei respectively. These established curves have potential to be employed for biodosimetry of occupational, clinical and accidental exposures, for initial triage and medical management.
INTERNATIONAL JOURNAL OF HUMAN GENETICS, 2013
Considerable progress has been made to study the pathophysiology of male infertility in the last ... more Considerable progress has been made to study the pathophysiology of male infertility in the last few years. About 10-15% of genetic causes such as chromosomal abnormality, single gene and multifactorial mutations may be a causative factor. Submicroscopic microdeletions on chromosome Y is considered to be the most frequent genetic defects associated with impaired spermatogenesis. Therefore, the aim of this present study was to assess pregnancy outcome of intracytoplasmic sperm injection (ICSI) in infertile men from 285 study subjects; fertile controls (n=110) and cases (n=175) with sperm count less than 5 millions/ml [azoospermia (n=150) and oligoasthenoteratozoospermia (n=25)]. Microdeletions located on chromosome Y-sY84, sY86 (AZFa), sY127, sY134 (AZFb), and sY254, sY255 (AZFc) were confirmed with Polymerase Chain Reaction (PCR). A 12.56% was observed in infertile men in one or more STS with a percentage of 1.14, 2.28, 9.14 for AZFa, b and c respectively. The azoospermia factor region c (AZFc) loci showed an increase in frequency when compared to AZFb and a regions. Intracytoplasmic Sperm Injection (ICSI) could be offered or an alternative method to patients with AZFc deletion.
Cytometry Part A, 2015
Measurement of γ‐H2AX protein changes in the peripheral blood lymphocytes (PBL) of individuals ex... more Measurement of γ‐H2AX protein changes in the peripheral blood lymphocytes (PBL) of individuals exposed to ionizing radiation is a simple, sensitive, and rapid assay for radiation triage and early marker of dose estimation. The qualitative and quantitative measurements of the protein changes were examined using flow cytometry and microscopy. Whole blood and isolated lymphocytes were exposed in vitro between 0.1 and 5 Gy doses of 60Co γ‐radiation at a dose rate of 1 Gy/min. Radiation induced γ‐H2AX foci frequency (n = 3) and relative fluorescence intensity (n = 7) in PBL was measured at 0.5 and 2 hrs postexposure. The observed dose response for γ‐H2AX foci frequency at both time points, for whole blood and isolated lymphocytes did not show any significant (P > 0.05) differences. However, when compared with γ‐H2AX foci frequency scored manually (microscopy), the semiautomated analysis (captured images) showed a better correlation (r2 = 0.918) than that obtained with automated (Metaf...
Dose-response : a publication of International Hormesis Society, 2014
While contradictory reports are available on the yield of dicentric chromosomes (DC) in blood sam... more While contradictory reports are available on the yield of dicentric chromosomes (DC) in blood samples stored at different temperature and stimulated to enter into cell cycle, various times gap followed by exposure, limited information is available on the micronucleus (MN) assay. As scoring the micronuclei frequency from the blood lymphocytes of exposed individuals is an alternative to the gold standard DC assay for triage applications, we examined radiation induced MN yield in delayed mitogenic stimulation after irradiation of in vitro. Peripheral blood lymphocytes (PBL) were exposed to low LET ((60)Co) radiation dose (0.1 to 5Gy) and incubated at 37°C for 2, 6 and 24 hours. The MN frequency obtained in blood samples stimulated 2 hours post-irradiation showed a dose dependent increase and used to construct the dose-response curve. Further, the results also showed that blood samples stimulated twenty four hours of post-irradiation, a significant reduction (p<0.05) in MN frequencie...
Applied radiation and isotopes : including data, instrumentation and methods for use in agriculture, industry and medicine, 2014
To facilitate efficient handling of large samples, an attempt towards networking of laboratories ... more To facilitate efficient handling of large samples, an attempt towards networking of laboratories in India for biological dosimetry was carried out. Human peripheral blood samples were exposed to (60)Co γ-radiation for ten different doses (0-5Gy) at a dose rate of 0.7 and 2Gy/min. The chromosomal aberrations (CA) were scored in Giemsa-stained and fluorescence in-situ hybridization with centromere-specific probes. No significant difference (p>0.05) was observed in the CA yield for given doses except 4 and 5Gy, between the laboratories, among the scorers and also staining methods adapted suggest the reliability and validates the inter-lab comparisons exercise for triage applications.