Exploring the Influence of Nanocrystalline Structure and Aluminum Content on High-Temperature Oxidation Behavior of Fe-Cr-Al Alloys.

The present study examines the high-temperature (500-800 °C) oxidation behavior of Fe-10Cr-(3,5) Al alloys and studies the effect of nanocrystalline structure and Al content on their resistance to oxidation. The nanocrystalline (NC) alloy powder was synthesized via planetary ball milling. The prepared NC alloy powder was consolidated using spark plasma sintering to form NC alloys. Subsequently, an annealing of the NC alloys was performed to transform them into microcrystalline (MC) alloys. It was observed that the NC alloys exhibit superior resistance to oxidation compared to their MC counterparts at high temperatures. The superior resistance to oxidation of the NC alloys is attributed to their considerably finer grain size, which enhances the diffusion of those elements to the metal-oxide interface that forms the protective oxide layer. Conversely, the coarser grain size in MC alloys limits the diffusion of the oxide-forming components. Furthermore, the Fe-10Cr-5Al alloy showed greater resistance to oxidation than the Fe-10Cr-3Al alloy.

Structural Evolution during Milling, Annealing, and Rapid Consolidation of Nanocrystalline Fe-10Cr-3Al Powder.

Structural changes during the deformation-induced synthesis of nanocrystalline Fe-10Cr-3Al alloy powder via high-energy ball milling followed by annealing and rapid consolidation by spark plasma sintering were investigated. Reduction in crystallite size was observed during the synthesis, which was associated with the lattice expansion and rise in dislocation density, reflecting the generation of the excess grain boundary interfacial energy and the excess free volume. Subsequent annealing led to the exponential growth of the crystallites with a concomitant drop in the dislocation density. The rapid consolidation of the as-synthesized nanocrystalline alloy powder by the spark plasma sintering, on the other hand, showed only a limited grain growth due to the reduction of processing time for the consolidation by about 95% when compared to annealing at the same temperature.

A new recurring chromosome 13 abnormality in two older patients with de novo acute myeloid leukemia: An Indian experience.

We report here two cases of trisomy 13 in acute myeloid leukemia M1 subtype. short-term unstimulated bone marrow and peripheral blood lymphocyte culture showed 47, XY, +13 in all metaphase plates and trisomy 13 was confirmed with whole chromosome paint probes. Trisomy 13 in AML-M1 is a rare numerical abnormality. This is the first Indian report of sole trisomy 13 in AML-M1. Here, we present two cases of elder male patients, which may constitute a distinct subtype.

Characterization of a familial small supernumerary marker chromosome in a patient with adult-onset tongue cancer.

Cytogenetic analysis in peripheral blood lymphocytes of a 50-year-old female with tongue cancer showed the presence of one to three copies of a small supernumerary marker chromosome (sSMC) in a mosaic state. Family studies also revealed the marker in mosaic form in four (age <29 years) of eleven clinically normal individuals studied from her family of 16 individuals spanning three generations. Due to the extremely small size of the marker chromosome, identification by classical cytogenetics was not informative. Multicolor FISH followed by whole chromosome painting identified the marker as a derivative of chromosome 21. This is the first report of sSMC21 in an adult-onset tongue cancer patient and some of her family members with no clinical symptoms.

A case of acute myeloid leukemia-M2 with trisomy 4 in addition to t(8;21).

t(8;21)(q22;q22) is the most frequently observed karyotypic abnormality associated with acute myeloid leukemia (AML), specifically in FAB-M2. Short-term unstimulated bone marrow (BM) and peripheral blood lymphocyte culture showed 47,XX, +4,t(8;21) in all metaphase plates; and interphase and metaphase results of AML-ETO fusion was positive and trisomy of 4 was confirmed with WCP probes. Trisomy 4 in AML with t(8;21) is a rare numerical abnormality. Here we present such case of patient which may constitute a distinctive subtype.

Constitutional tetrasomy 18p.

We present here the first case of constitutional tetrasomy 18p from India. A 3 year old female with developmental delay and dysmorphic features revealed 47,XX,+mar karyotype. The small meta-centric marker chromosome was identified as i(18p) with m-FISH followed by m-BAND. Parents and a normal sibling of the proband revealed normal karyotype. There was history of mental retardation and dysmorphic features in four cases on paternal side; however, their karyotype was also normal.

A study of chromosome aneuploidy in hereditary breast cancer patients and their healthy blood relatives.

Chromosomal abnormalities that may predispose a group of individuals to develop certain neoplasms have been reported in lymphocytes. We evaluated cytogenetic abnormalities in 21 histopathologically confirmed primary breast cancer patients (BCPs), 52 healthy blood relatives (HBRs), belonging to 19 hereditary breast cancer families (HBFs) and 25 females as control. Phytohemagglutinin stimulated peripheral blood lymphocyte (PBL) cultures were used to study the chromosomal abnormalities in BCPs and their HBRs. Short term culture of the tumor tissue was also carried out in defined growth medium. Suitable metaphases (11 to 55) from tumors and a minimum of 100 metaphases from PBL were karyotyped for the cytogenetic analysis. Heterogeneous population of cells with random and nonrandom chromosomal abnormalities was noticed in tumors. In control groups 2-5% of metaphases showed numerical abnormalities, whereas this phenomenon was observed in 3-18% of metaphases in HBRs and 3-23% of metaphases in BCPs. In tumor tissue, 47.05% of BCPs showed numerical abnormalities in more than 16 metaphases. In lymphocytes, this event was observed in 33.33% of BCPs and 13.14% of HBRs. In controls 1.28%, in BCPs 52.04% (tumor) and 13.42% (lymphocytes), and in HBRs 9.03% of metaphases were found aneuploid. Statistically it was highly significant (Fisher's exact test, P<0.00001). In lymphocytes of BCPs, chromosomes 1, 6, 8, 9, 15, 17, 18, 20, and X and in HBRs, chromosomes 8, 15, 17, 18, and X were frequently involved. It can be inferred from the findings that the above mentioned chromosomes may have an important role in early stage of breast carcinogenesis in BCFs. Moreover, presence of similar abnormalities in HBR indicates inherited pattern of this genetic error among them.

Bleomycin-induced chromosome damage in lymphocytes indicates inefficient DNA repair capacity in breast cancer families.

In vitro mutagen susceptibility has been observed as a predictor of cancer risk. To evaluate susceptibility to mutagen, we have studied the response to in vitro bleomycin (BLM) treatment in cultured peripheral blood lymphocytes (PBL) of 9 breast cancer families (BCFs). Eleven breast cancer patients (BCPs) and 36 healthy blood relatives (HBRs) from BCFs were included in the study. Data were compared with 22 healthy control women. The frequencies of chromosomal aberrations were evaluated after exposure to BLM in the last five hours. Mean frequency of BLM-induced chromosomal aberrations per cell (CA) observed among BCPs was significantly higher as compared to their HBRs as well as control subjects. Moreover, mean BLM-induced CA/cell value observed for HBRs was also significantly higher than that of control subjects. In comparison to controls, it was observed that there was four times more cancer risk in BCPs (OR=4.148, 95% CI=5.83-687.46) and 2.5 times more cancer risk in HBRs (OR=2.67, 95% CI=5.31-39.25). Lymphocytes from 90% of BCPs and 69% of HBRs were found to be sensitive to BLM (using a cutoff value = controls group mean + 1 SD). Thus, lymphocytes of BCPs and their HBRs were more sensitive to BLM exposure as compared to controls. Our finding indicated inefficient DNA repair capacity in BCFs. The HBRs in BCFs, having increased BLM-sensitivity, may be at higher risk to develop a similar cancer.

Spontaneous chromosomal instability in breast cancer families.

Spontaneous chromosomal instability has been correlated with cancer predisposition. In the present study, the phenomenon has been evaluated using two cytogenetic markers, namely, frequency of spontaneous sister chromatid exchanges (SCE) and spontaneous chromosomal aberrations (CA) in peripheral blood lymphocytes of hereditary breast cancer (HBC) patients (n = 11) and healthy blood relatives (HBR, n = 36). A statistically significant difference was observed for both the endpoints between HBC patients and controls (P < 0.001), HBC patients and HBR (P < 0.001), as well as HBR and controls (P < 0.001). Thus, 63.64% of the HBC patients and 25% of HBR showed a mean CA/cell value higher than the highest mean CA/cell value of the controls (0.11 CA/cell). Similarly, 81.81% of the HBC patients and 61.11% of HBR showed a mean SCE/cell value higher than the highest mean SCE/cell value of the controls (9.60 SCE/cell). Chromosomal aberrations were more frequently observed in the B and E group of chromosomes in HBC patients and HBR. These findings primarily indicate the high level of chromosomal instability in breast cancer families, and might be one of the predisposing factors for high risk of cancer in HBR.

Chromosomal aberrations in young cancer patients.

Spontaneous level of chromosomal aberrations (CA) is considered to be indicative of inherent cancer predisposition, which plays a major role in total cancer incidence. We have studied spontaneous CA levels in in vitro cultured peripheral blood lymphocytes of pediatric cancer patients (n = 77). Results were compared with those of control subjects (n = 72), including: age-matched controls; elder controls (minimum age 60 years); and healthy first-degree relatives (FDR) of pediatric cancer patients. Pediatric cancer patients showed the highest mean CA/cell value, which was statistically significant as compared to their age-matched counterparts, elder controls, and the FDRs. As compared to 7% of all the three control groups collectively, 32.4% of pediatric cancer patients showed > 0.1 mean CA/cell value. One of the FDRs with a very high frequency of CA developed cancer within three years. The results suggest that spontaneous levels of chromosomal aberrations may be used as one of the biomarkers for cancer predisposition study.

Mitomycin C induced chromosomal aberrations in young cancer patients.

Mitomycin-C (MMC) induced Chromosomal aberration (CA) frequencies were studied in 48 h peripheral blood lymphocyte (PBL) cultures of untreated cancer patients of young age (maximum age 12 years, n=77). Control population (n=71) consisted of age-matched group (maximum age 12 years, n=21); elder controls (minimum age 60 years, n=19) and healthy first degree relatives, i.e., parents or siblings of the pediatric cancer patients (mean age 24.3 years, n=31) as they share their genome and environment. Induced CA levels were found to be significantly higher among pediatric cancer patients as compared to control groups. The age-matched and elder control groups showed comparable CA levels. The first degree relatives controls showed higher induced CA levels as compared to pediatric and elder control groups. The present results indicate that there are different degrees of mutagen sensitivity prevailing in normal population. This may be responsible for differential cancer proneness. High degree of mutagen sensitivity in cancer patients may also be playing a major role in cancer onset at an early age.

A complex translocation involving chromosomes 2, 9 and 22 in a patient with chronic myeloid leukemia.

A patient with a high leukocyte count, diagnosed with chronic myeloid leukemia was referred for cytogenetic study. Peripheral blood and bone marrow cells were cultured without mitogenic stimulation. All karyotypes represented rare, varient Philadelphia chromosome with-three way translocation, i.e. t (2; 9; 22) (p13; q34; q11).

Elevated mutagen susceptibility in cultured lymphocytes of oral cancer patients.

Mitomycin C (MMC)-induced lymphocytic sister chromatid exchange (SCE) frequency was studied in 40 oral cancer (OC) patients, 40 normal tobacco chewers (NC) and in 40 normal healthy individuals not consuming tobacco/areca nut in any form. Significantly higher MMC-induced SCE/cell values were observed among OC patients as compared to healthy non-chewer controls as well as NC. Although the mean SCE frequency for NC was comparable to that of healthy controls, three individuals showed an SCE rate higher than the highest observed among controls. The comparable frequency of the tobacco habit in these three individuals with that of the rest of the thirty-seven individuals indicated the possible involvement of factors other than tobacco consumption for the higher susceptibility to mutagens.

Pan masala--a genotoxic menace.

Cytogenetic markers such as chromosome aberration (CA), sister-chromatid exchange (SCE) and micronucleated cells (MNC) were used to assess the genotoxic potential of dimethyl sulphoxide (DMSO) extract of pan masala with and without tobacco (PM-T and PM). Using in vitro short-term assays, the extracts were tested in the presence or absence of metabolic activation. In cultures without metabolic activation the extracts were found to increase the frequency of all the three parameters tested significantly, however those with activation elicited a weak response, implying that pan masalas contain solvent (DMSO)-soluble direct-acting mutagen.

Chromosome damaging effects of pan masala.

Effects of aqueous extracts of a popular brand of pan masala with and without tobacco (PM-T and PM) were studied for short duration treatment employing an in vitro system. Metabolic activation with S9 mix was also included. Frequency of all the three cytogenetic endpoints viz., chromosome aberration (CA); sister chromatid exchange (SCE) and % micronucleated cells (% MNC) were found to be elevated significantly in a dose-dependent manner in cultures without metabolic activation. However, addition of S9 activation system resulted in suppression of chromosomal damage. Our findings indicate that pan masalas contain water soluble direct acting mutagens.