16 research outputs found
Environmental radiation as the conditioning factor for the survival of yeast <i><span style="font-size:14.0pt;line-height:115%;font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";color:black;mso-ansi-language:EN-IN; mso-fareast-language:EN-IN;mso-bidi-language:HI" lang="EN-IN">Saccharomyces cerevisiae</span></i>
No full text95-100Whether
natural radiation can be a conditioning factor for the growth and survival of a
living organism was investigated using diploid yeast S. cerevisiae D7. Yeast cells were
conditioned by growing them continuously for at least 100 generation in 3
different radiation background such as i) ambient radiation (1.1 mSv/y), ii)
sub-ambient radiation (0.44 mSv/y, within a shielded chamber) and iii) an
elevated background radiation (88 and 880 mSv/y in a γ-field). At the end, the
cells were challenged with 60Co γ, 100 Gy and the viable fractions
were determined. Conditioning the cells in 880 mSv/y and in ambient radiation,
enabled the cells to reduce the deleterious effect of the challenging dose
significantly (P < 0. 05) compared to that of sub-ambient radiation.
The cellular viability of yeast cultures seems to be influenced by the
prevailing radiation
background, apart from
starvation. Comparatively, a rapid decline in viability was noticed when the
cultures were incubated for 60 days in the shielded chamber. The results
indicate that some amount of radiation equivalent to background level or little
above is needed to confer fitness in biological systems against stress factors,
including radiation. The adaptive dose for the diploid yeast was also
determined by single exposure. The priming dose ranged from 0.01 to 1.2 Gy. An adaptive
dose of 0.25 or 0.4 Gy, almost nullified the deleterious effect of the
challenging dose. The adaptive response may have a greater role in the field of
cancer therapy and in radiation risk assessment. Understanding the response of
an organism at different radiation-background will be helpful for successful
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Standardisation and Validation of Cytogenetic Markers to Quantify Radiation Absorbed Dose
No full textThe amounts of radiation exposure received by radiation workers are monitored generally by physical dosimeters like thermoluminescence dosimeter (TLD) and film badge. However, in practice the over-exposure recorded by physical dosimeters need to be confirmed with biological dosimeters. In addition to confirming the dose recorded by physical dosimeters, biological dosimeters play an important role in estimating the doses received during accidental exposures. Exposure to high levels of radiation induces certain biochemical, biophysical, and immunological changes (biomarkers) in a cell. Measurement of these changes are generally precise but cannot be effectively used to assess the dose, as the level of these changes return to normalcy within hours to months after exposure. Thus, among various biological indicators, cytogenetic indicators are considered practical and reliable for dose estimation. The paper highlights the importance and establishment of biodosimetry facility using genetic markers such as the sensitive dicentric chromosomes, rapid micronucleus assay and stable translocations measured using fluorescence in situ hybridisation and GTG banding for retrospective dose estimation. Finally, the development of gH2AX assay, as a potential marker of triage dosimeter, is discussed.Defence Science Journal, 2011, 61(2), pp.125-132, DOI:http://dx.doi.org/10.14429/dsj.61.83
Original Communication - Detection of Helicobactor pylori by polymerase chain reaction: A comparison in sample preparation
No full textGastric biopsy samples obtained from 14 patients with upper abdominal
pain, clinically diagnosed as acid peptic disease, were analysed for
the presence of Helicobacter pylori (H. pylori) by Polymerase Chain
Reaction (PCR) using partially (template A) and completely purified DNA
(template B). Antigen specific primer was used to analyse the sample by
PCR method. The presence of H. pylori in the samples was confirmed by
running a positive control. The presence of H. pylori was also
detected by urease method using standard protocol. Among the 14 samples
studied, 8 showed the presence of H. pylori with both templates A and
B. Among these 8 samples only 3 showed positive for the presence of H.
pylori with urease method. The present work discusses the results
obtained in the detection of H. pylori in template A and B by PCR
method
Original Communication - Detection of Helicobactor pylori by polymerase chain reaction: A comparison in sample preparation
No full textGastric biopsy samples obtained from 14 patients with upper abdominal
pain, clinically diagnosed as acid peptic disease, were analysed for
the presence of Helicobacter pylori (H. pylori) by Polymerase Chain
Reaction (PCR) using partially (template A) and completely purified DNA
(template B). Antigen specific primer was used to analyse the sample by
PCR method. The presence of H. pylori in the samples was confirmed by
running a positive control. The presence of H. pylori was also
detected by urease method using standard protocol. Among the 14 samples
studied, 8 showed the presence of H. pylori with both templates A and
B. Among these 8 samples only 3 showed positive for the presence of H.
pylori with urease method. The present work discusses the results
obtained in the detection of H. pylori in template A and B by PCR
method
Influence of initial large dose on subsequent uptake of therapeutic radioiodine in thyroid cancer patients
No full textFifty-two patients with differentiated thyroid cancer, following thyroidectomy were studied by administering a quantity of up to 5 mCi of [131I]sodium iodide. In most of these patients, radioiodine uptake values obtained with the subsequent therapeutic dose were markedly lower than those observed with the initial doses. This observation was verified in seven of the patients with differentiated thyroid cancer, by measuring the radioiodine uptake with a second dose of 4.5 mCi of [131I]sodium iodide. Calculations showed that the major etiology was probably therapeutic irradiation of the thyroid by the first dose
Disappearance rate of endogenously radioiodinated thyroglobulin and thyroxine after radioiodine treatment
No full textEndogenously radioiodinated thyroglobulin (tg) and thyroxine (T4), in the circulation following, therapeutic doses of radioiodine were studied in five patients with differentiated thyroid carcinoma. Radioactive serum was fractionated on a Sephadex G-200 and the various radioactive peaks thus obtained were analyzed for their biochemical and immunologic characteristics using precipitation with trichloroacetic acid (TCA) and antithyroglobulin antibody extraction with acidified n-butanol and electrophoresis on agar gel. The disappearance rates of endogenously labelled tg and T4 were 3.12 ± 0.396 days and 10.14 ± 1.81 days, respectively
