Gene polymorphisms,tobacco exposure and oral cancer susceptibility: a study from Gujarat,West India

Polymorphic variability in the enzymes involved in biotransformation of tobacco‐related pro‐carcinogens plays an important role in modulating oral cancer susceptibility. CYP1A1*2A, CYP1A1*2C, GSTM1 and GSTT1 polymorphisms were determined in 122 oral carcinoma cases and 127 controls from Gujarat, West India using PCR‐based methods. The results revealed that the polymorphic variants of CYP1A1 gene did not show association towards oral cancer risk. The GSTM1 and GSTT1 null genotypes were found to be over‐represented in patients than controls, suggesting a moderate increase in risk of oral cancer. The oral cancer risk was significantly increased in the patients having either alone or concurrent deletion of GSTM1 and GSTT1. The results also suggested significant association between tobacco habits, especially chewing, variant genotypes of CYP1A1, GSTM1 and GSTT1 and oral cancer risk. Our data have provided evidence that GST polymorphism modified the susceptibility to oral cancer and individuals with variant genotypes of the three genes with tobacco habits are at significant risk of developing oral cancer.     

From the Cover: Large sulfur-isotope anomaly in nonvolcanic sulfate aerosol and its implications for the Archean atmosphere

Sulfur-isotopic anomalies have been used to trace the evolution of oxygen in the Precambrian atmosphere and to document past volcanic eruptions. High-precision sulfur quadruple isotope measurements of sulfate aerosols extracted from a snow pit at the South Pole (1984–2001) showed the highest S-isotopic anomalies (Δ³³S = +1.66‰ and Δ³⁶S = +2‰) in a nonvolcanic (1998–1999) period, similar in magnitude to Pinatubo and Agung, the largest volcanic eruptions of the 20th century. The highest isotopic anomaly may be produced from a combination of different stratospheric sources (sulfur dioxide and carbonyl sulfide) via SO_x photochemistry, including photoexcitation and photodissociation. The source of anomaly is linked to super El Niño Southern Oscillation (ENSO) (1997–1998)-induced changes in troposphere–stratosphere chemistry and dynamics. The data possess recurring negative S-isotope anomalies (Δ³⁶S = −0.6 ± 0.2‰) in nonvolcanic and non-ENSO years, thus requiring a second source that may be tropospheric. The generation of nonvolcanic S-isotopic anomalies in an oxidizing atmosphere has implications for interpreting Archean sulfur deposits used to determine the redox state of the paleoatmosphere.Sulfur is a ubiquitous element on Earth. Its multiple valence states (S⁻² to S⁺⁶) permit it to participate in a range of photochemical, geochemical, and biochemical processes, and its four stable isotope (³²S, ³³S, ³⁴S, and ³⁶S) allow tracing of chemical reactions at a molecular level. Multiple sulfur isotopes (δ³³S, δ³⁴S, and δ³⁶S) and concomitant anomalies (Δ³³S and Δ³⁶S)^‡ in paleo-sediments [>2.5 giga-annum (Ga)] have been used to trace the origin and evolution of life and rise of oxygen in the Earth’s paleoclimatic history (1–3). In the present atmosphere, the concentration of sulfate in ice cores and associated S-isotope anomalies has served as a forensic tool to help understand the dynamics of volcanic emissions, such as transport and transformation of sulfur to the stratosphere and its impact on ozone chemistry (4–7). The low concentration of sulfate (SO₄^2-) in ice cores during volcanically quiescent periods and associated analytical challenges to analyze all four S-stable isotopes at high precision have restricted studies of the temporal distribution of sulfur mass-independent signatures. Here, we present a high-resolution seasonal record (1984–2001) of quadruple S-stable isotopes and concomitant isotope anomalies of sulfate aerosols extracted from a snow pit (1 × 1 m) at the South Pole (89.5° S, 17.3° W; 2,850 m) (8) to gain further insight into sources, photochemistry, and associated sulfur transformations of stratospheric sulfate aerosols (SSAs). The time period encompasses two major volcanic eruptions and three large El Niño Southern Oscillation (ENSO) events. A recent study has attributed a global warming hiatus (9) to a super ENSO event (1997–1998); therefore, data from this period are timely for understanding changes in stratospheric sulfate aerosol chemistry that play an important role in mitigating global warming trends via scattering of incoming solar radiation. Oxygen triple isotope measurements of sulfate aerosols (1980–2002) have recently revealed how ENSO-driven changes affect the global transport and transformation of sulfate aerosols from the troposphere to the stratosphere and across hemispheres (10).     

Operational radiologic image archive on digital optical disks

A digital optical disk archive for storage of computed radiographic, computed tomographic, magnetic resonance, ultrasonographic, and digitized film radiographic images was installed. In the system, digital images enter a minicomputer, are temporarily stored on magnetic disks, and are archived onto write-once read-many optical disks at their full resolution. A pictorial index of minified images is maintained for each patient. After 8 months of operation, 49,400 megabytes of images had been retained on 19 optical disks stored, after January 1987, in a mechanical jukebox-style optical disk library. The success rate for archival capture of images during the initial period was 96.6%. The failures were due to overfilling of the magnetic disk, a problem addressed through the addition of a second magnetic disk unit. There were no medium-related image errors during the early period. Problems resulting from the slow speed of optical disk systems were addressed operationally by initiating recall of a patient's archived images from the optical to the faster magnetic disk as soon as the system received a request to acquire a new image. Also, optical disk retrieval times are expected to improve with technologic development.     

The biochemical and genetic basis for the microheterogeneity of human R- type vitamin B12 binding proteins

R-type vitamin B12 binding proteins (R proteins) from human granulocytes, erythrocytes, plasma, and other body fluids were characterized by isoprotein banding patterns on autoradiograms after resolution via thin-layer polyacrylamide isoelectric focusing (IEF) gel electrophoresis. R proteins obtained from various tissue sources in a given individual show tissue-specific electrophoretic patterns. The desialated R proteins obtained following in vitro treatment with neuraminidase are, however, the same for any given individual and do not show tissue specificity. The differences seen in native R proteins (i.e., transcobalamin I, III, and others) obtained from different tissues are due to variations only in the sialic acid content. Granulocytes from patients with chronic myelogenous leukemia (CML) contain both TC I and TC III, and these R proteins can be released in vitro by lithium stimulation. Normal granulocytes contain only TC III. Differences in desialated R proteins from individual to individual are due to a genetic polymorphism controlled by a single genetic locus (designated TCR) with two alleles, 1 and 2, which are found to be codominantly expressed in heterozygous individuals. The allelic variants of the desialated R proteins found in different blood cells and body fluids are controlled by only one genetic locus.