Conventional Pap smear and liquid-based cytology as screening tools in low-resource settings in Latin America: experience of the Latin American screening study

OBJECTIVE: To evaluate the performance of the conventional Pap test and liquid-based cytology (LBC) in an ongoing multicenter trial testing optional screening tools (cytology, screening colposcopy, visual inspection with acetic acid, visual inspection with Lugol's Iodine, cervicography and Hybrid Capture II [HCII] (Digene Brazil, S?o Paulo, Brazil) conventional and self-sampling), for cervical cancer in Brazil and Argentina. STUDY DESIGN: A cohort of 12,107 women attending four clinics (Campinas, S?o Paulo, Porto Alegre, Buenos Aires) were randomized into the 8 diagnostic arms. Women testing positive with any of the tests were referred for colposcopy, and cervical biopsies were used as the gold standard to assess performance characteristics of the diagnostic tests. Conventional Pap smears were sampled by all clinics (n = 10,240), and LBC (Autocyte PREP, [TriPath Imaging, Burlington, North Carolina, U.S.A.], n=320, and DNA-Citoliq [Digene Brazil], n =1,346) was performed by 1 of the clinics. RESULTS: Conventional Pap smears showed no squamous intraepithelial lesions (normal) in 8,946 (87.4%) and LBC in 1,373 (82.4%). Using high grade squamous intraepithelial lesions (HSIL) as the cutoff, Pap smears predicted high grade (cervical intraepithelial neoplasia [CIN] 3) with OR 63.0 (95% CI, 36.90-107.70), standard error (SE) 59%, SP 97.8%, positive predictive value (PPV) 68.1% and negative predictive value (NPV) 96.7%. The same figures for Autocyte PREP were: OR 9.0 (95% CI, 2.43-33.24), sensitivity (SE) 33.3%, specificity (SP) 100%, PPV 100% and negative PV (NPV) 88.8%. DNA-Citoliq detected CIN 3 as follows: OR 11.8 (95% CI 2.60-53.26), SE 40.0%, SP 94.6%, PPV 40.0% and NPV 94.6%. Lowering the cutoff to low grade squamous intraepithelial lesions increased SE and NPV but compromised SP and PPV. The detection rates for high grade lesions after an atypical squamous cells of undetermined significance diagnosis were similar with the 3 techniques. In our settings, the 3 methods of cervical cytology were slightly different in performance. The conventional Pap smear had the highest SE, while Autocyte PREP had 100% SP and PPV in detecting CIN3 with the HSIL cutoff. All 3 tests had lower SE but higher SP as compared to HCII.     

Effects of Submerged Vegetation on Water Clarity Across Climates

A positive feedback between submerged vegetation and water clarity forms the backbone of the alternative state theory in shallow lakes. The water clearing effect of aquatic vegetation may be caused by different physical, chemical, and biological mechanisms and has been studied mainly in temperate lakes. Recent work suggests differences in biotic interactions between (sub)tropical and cooler lakes might result in a less pronounced clearing effect in the (sub)tropics. To assess whether the effect of submerged vegetation changes with climate, we sampled 83 lakes over a gradient ranging from the tundra to the tropics in South America. Judged from a comparison of water clarity inside and outside vegetation beds, the vegetation appeared to have a similar positive effect on the water clarity across all climatic regions studied. However, the local clearing effect of vegetation decreased steeply with the contribution of humic substances to the underwater light attenuation. Looking at turbidity on a whole-lake scale, results were more difficult to interpret. Although lakes with abundant vegetation (>30%) were generally clear, sparsely vegetated lakes differed widely in clarity. Overall, the effect of vegetation on water clarity in our lakes appears to be smaller than that found in various Northern hemisphere studies. This might be explained by differences in fish communities and their relation to vegetation. For instance, unlike in Northern hemisphere studies, we find no clear relation between vegetation coverage and fish abundance or their diet preference. High densities of omnivorous fish and coinciding low grazing pressures on phytoplankton in the (sub)tropics may, furthermore, weaken the effect of vegetation on water clarity.     

Properties of microtubule sliding disintegration in isolated tetrahymena cilia

Properties of the sliding disintegration response of demembranated tetrahymena cilia have been studied by measuring the spectrophotomeric response or turbidity of cilia suspensions at a wavelength of 350 nm relative to changes in the dynein substrate (MgATP(2-)) concentration. The maximum decrease in turbidity occurs in 20 muM ATP, and 90 percent of the decrease occurs in approximately 5.9 s. At lower ATP concentrations (1-20 muM), both the velocity and magnitude of the turbidity decreases are proportional to ATP concentration. The velocity data for 20 muM ATP permit construction of a reaction velocity curve suggesting that changes in turbidity are directly proportional to the extent and velocity of disintegration. At ATP concentrations more than 20 muM (50muM to 5mM), both velocity and magnitude of the turbidimetric response are reduced by approximately 50 percent. This apparent inhibition results in a biphasic response curve that may be related to activation of residual shear resistance or regulatory components at the higher ATP concentrations. The inhibitory effects of elevated ATP can be eliminated by mild trypsin proteolysis, whereupon the reaction goes to completion at any ATP concentration. The turbidimetric responses of the axoneme-substrate suspensions are consistent with the extent and type of axoneme disintegration revealed by electron microscope examination of the various suspensions, suggesting that the turbidimetric assay may prove to be a reliable means for assessing the state of axoneme integrity.     

Carbon Sequestration in a Large Hydroelectric Reservoir: An Integrative Seismic Approach

Artificial reservoirs likely accumulate more carbon than natural lakes due to their unusually high sedimentation rates. Nevertheless, the actual magnitude of carbon accumulating in reservoirs is poorly known due to a lack of whole-system studies of carbon burial. We determined the organic carbon (OC) burial rate and the total OC stock in the sediments of a tropical hydroelectric reservoir by combining a seismic survey with sediment core sampling. Our data suggest that no sediment accumulation occurs along the margins of the reservoir and that irregular bottom morphology leads to irregular sediment deposition. Such heterogeneous sedimentation resulted in high spatial variation in OC burial—from 0 to 209 g C m^?2 y^?1. Based on a regression between sediment accumulation and OC burial rates (R ² = 0.94), and on the mean reservoir sediment accumulation rate (0.51 cm y^?1, from the seismic survey), the whole-reservoir OC burial rate was estimated at 42.2 g C m^?2 y^?1. This rate was equivalent to 70% of the reported carbon emissions from the reservoir surface to the atmosphere and corresponded to a total sediment OC accumulation of 0.62 Tg C since the reservoir was created. The approach we propose here allows an inexpensive and integrative assessment of OC burial in reservoirs by taking into account the high degree of spatial variability and based on a single assessment. Because burial can be assessed shortly after the survey, the approach combining a seismic survey and coring could, if applied on a larger scale, contribute to a more complete estimate of carbon stocks in freshwater systems in a relatively short period of time.     

Endocervical glandular cell abnormalities in conventional cervical smears: evaluation of the performance of cytomorphological criteria and HPV testing in predicting neoplasia

Objective:  To analyse the correlation between cytomorphological criteria in smears with atypical glandular cells (AGC) or adenocarcinoma in situ (AIS) and human papillomavirus (HPV) reflex test results with different neoplastic histological diagnoses, particularly to distinguish between glandular and squamous neoplasia.
Methods:  A series of 155 women with glandular abnormalities in their conventional cervical smears was included: 106 with AGC, 35 with AGC associated with high-grade squamous intraepithelial lesion (HSIL) and 14 with AIS. Two reviewers evaluated 35 cytomorphological criteria and hybrid capture II (HCII) was performed in all cases. Colposcopy was carried out in all cases and biopsy in 126/155. For statistical purposes, predictive values and odds ratio (OR) were calculated, followed by chi-square automatic interaction detection.
Results:  Histology detected 56 cases of squamous and 17 of glandular intraepithelial or invasive neoplasia. Predictive values of the papillary groups and feathering criteria for glandular neoplasia were, respectively, 80.0% and 73.3%. Feathering was the criterion with the highest OR for distinguishing glandular from squamous neoplasia and also for distinguishing between glandular and non-neoplastic diagnosis. Rosettes and pseudostratified strips did not perform as well. Multivariant Classification and Regression Trees analysis identified feathering as the best criterion for distinguishing between glandular, squamous and non-neoplastic diagnoses regardless of HPV status.
Conclusions:  Feathering was the best criterion for predicting glandular neoplasia.     

Thermostable phycocyanin from the red microalga <Emphasis Type="Italic">Cyanidioschyzon merolae</Emphasis>, a new natural blue food colorant

The demand for natural food colorants is growing as consumers question the use of artificial colorants more and more. The phycobiliprotein C-phycocyanin of Arthospira platensis is used as a natural blue colorant in certain food products. The thermoacidophilic red microalga Cyanidioschyzon merolae might provide an alternative source of phycocyanin. Cyanidioschyzon merolae belongs to the order Cyanidiophyceae of the phylum Rhodophyta. Its natural habitat are sulfuric hot springs and geysers found near volcanic areas in, e.g., Yellowstone National Park in the USA and in Java, Indonesia. It grows optimally at a pH between 0.5 and 3.0 and at temperatures up to 56 °C. The low pH at which C. merolae grows minimizes the risk of microbial contamination and could limit production loss. As C. merolae lacks a cell wall, phycocyanin with a high purity number of 9.9 could be extracted by an osmotic shock using a simple ultrapure water extraction followed by centrifugation. The denaturation midpoint at pH 5 was 83 °C, being considerably higher than the A. platensis phycocyanin (65 °C). The C. merolae phycocyanin was relatively stable at pH 4 and 5 up to 80 °C. The high thermostability at slightly acidic pH makes the C. merolae phycocyanin an interesting alternative to A. platensis phycocyanin as a natural blue food colorant.     

Tissue Aluminum Concentration Does Not Affect the Genomic Stability of ERBB2, C-MYC, and CCND1 Genes in Breast Cancer

It has long been hypothesized that body tissue uptake of aluminum may have biological implications in breast cancer. In vitro and in vivo studies have shown that aluminum may trigger genomic instability by interfering with DNA strands. The objective of this study was to examine the relationship between aluminum concentrations in the peripheral and central areas of breast tumors with the instability of three key genes in breast cancer, ERBB2, C-MYC, and CCND1 and aneuploidy of the chromosomes harboring these genes. Tissue samples of 118 women treated for breast cancer were obtained. Evaluation of aluminum content was carried out using graphite furnace atomic absorption spectrometry. A tissue microarray slide containing the tumor samples was used in FISH assays to assess ERBB2, C-MYC, and CCND1 expressions as well as the statuses of their respective chromosomes 17, 8, and 11. Clinicopathological data were obtained from patient’s records. Aluminum levels of >2.0 mg/kg were found in 20.3 and 22.1 % of the central and peripheral breast tumor areas, respectively. Amplification and/or aneuploid-positive statuses for ERBB2/CEP17, C-MYC/CEP8, and CCND1/CEP11 were detected in 24, 36.7, and 29.3 % of the tumors, respectively. We found that aluminum concentration was not related to these altered gene statuses. Our findings suggest that aluminum concentration does not affect genomic stability in breast tissues. Tissue microenvironment modifications, due to the presence of aluminum compounds, seem more appealing as a possible target for future studies to determine the implications of aluminum in breast carcinogenesis.