Multivariate analysis of 3D ToF-SIMS images: method validation and application to cultured neuronal networks.

Advanced data analysis tools are crucial for the application of ToF-SIMS analysis to biological samples. Here, we demonstrate that by using a training set approach principal components analysis (PCA) can be performed on large 3D ToF-SIMS images of neuronal cell cultures. The method readily provides access to sample component information and significantly improves the images' signal-to-noise ratio (SNR).

Eolian biogenic detritus in deep sea sediments: a possible index of equatorial ice age aridity.

Opal phytoliths and freshwater diatoms, transported mainly in dust to the equatorial Atlantic, are common in sediments deposited when ocean waters were cool, and sparse in those deposited when waters were warm, during the last 1.8 million years. Climate in source areas of the southern Sahara apparently was more arid during glacials and more humid during interglacials.

Defining the structure of membrane-bound human blood coagulation factor Va.

BACKGROUND: Blood coagulation factor (F) Va is the essential protein cofactor to the serine protease FXa. Factor Va stimulates the thrombin-to-prothrombin conversion by the prothrombinase complex, by at least five orders of magnitude. Factor Va binds with very high affinity to phosphatidylserine containing phospholipid membranes, which allows the visualization of its membrane-bound state by transmission electron microscopy (EM). METHODS: In this paper we present an averaged three-dimensional structure of FVa molecules attached to phosphatidylserine containing lipid tubes, as determined by EM and single particle analysis. The low-resolution FVa three-dimensional structure is compared with the available atomic models for FVa. RESULTS: The experimental data are combined with the most suitable atomic model and a membrane-bound FVaEM model is proposed that best fits the protein density defined by EM. In the FVaEM model, the C1 and C2 membrane-binding domains are juxtaposed onto the membrane surface and the model geometries indicate a deeper insertion of both C domains into the lipid bilayer than has been previously suggested. CONCLUSION: The present structure is a first step towards a higher-resolution experimental structure of a human FVa molecule in its membrane-bound conformation, allowing the visualization of individual domains within FVa and its association with the membrane.

Growth of single-layer boron nitride dome-shaped nanostructures catalysed by iron clusters.

We report on the growth and formation of single-layer boron nitride dome-shaped nanostructures mediated by small iron clusters located on flakes of hexagonal boron nitride. The nanostructures were synthesized in situ at high temperature inside a transmission electron microscope while the e-beam was blanked. The formation process, typically originating at defective step-edges on the boron nitride support, was investigated using a combination of transmission electron microscopy, electron energy loss spectroscopy and computational modelling. Computational modelling showed that the domes exhibit a nanotube-like structure with flat circular caps and that their stability was comparable to that of a single boron nitride layer.

Cigarette smoking and other risk factors for cervical dysplasia in southwestern Hispanic and non-Hispanic white women.

To assess smoking-related and other risk factors for high-grade cervical dysplasia in southwestern Hispanic and non-Hispanic white women in New Mexico, we conducted a clinic-based case-control study among attendees at university-affiliated gynecology clinics. We collected data on cigarette use, sexual behavior, past and current sexually transmitted diseases, hygienic practices, contraception, and diet. For both ethnic groups combined, after adjustment for the effects of human papillomavirus, sexual behavior, and other risk factors, cigarette smoking at the time of diagnosis was associated with high-grade dysplasia (odds ratio, 1.7; 95% confidence limits, 1.0-2.8). In contrast, former smoking was not associated with cervical dysplasia (odds ratio 0.9; 95% confidence limits, 0.5-1.5). Analyses showed dose-response relationships for the amount of cigarettes smoked per day and for cumulative exposure (pack-years of use) in association with cervical dysplasia. Although our study lacked the power to show statistically significant ethnic differences in smoking-related risks for dysplasia, smoking at the time of diagnosis, high pack-years of use, and smoking at the time of menarche were associated with dysplasia only for non-Hispanic white versus Hispanic women. Our data support hypotheses that implicate cigarette use as an etiological factor in the development of high-grade cervical dysplasia and suggest ethnic differences in risks for dysplasia among women attending the same clinics.

Contraceptive and reproductive risks for cervical dysplasia in southwestern Hispanic and non-Hispanic white women.

BACKGROUND: Various contraceptive practices and reproductive factors have been associated with cervical neoplasia in case-control studies worldwide. METHODS: To investigate contraceptive and reproductive risk factors associated with high-grade cervical dysplasia in southwestern Hispanic and non-Hispanic white women, we carried out a clinic-based case-control study among university-affiliated clinic attendees. RESULTS: Oral contraceptive use ever (odds ratio [OR] = 0.4, 95% confidence interval [CI]: 0.2-0.9) and past diaphragm use (OR = 0.3, 95% CI: 0.1-0.8) were protective for dysplasia in analyses adjusted for age, ethnicity, sexual behaviour, and for cervical papillomavirus (HPV) infection. After further adjustment for Pap smear screening interval, oral contraceptive use ever remained protective for dysplasia. Vaginal deliveries were strongly associated with dysplasia with > 2 vaginal deliveries associated with a 3.9-fold increase in risk after adjustment for age, ethnicity, sexual behaviour, and HPV infection. Using logistic regression models to simultaneously control for effects of multiple factors as potentially related to cervical dysplasia, we found low educational attainment, cervical HPV infection, cigarette smoking, history of any sexually transmitted disease, and having one or more vaginal deliveries to be associated with dysplasia; oral contraceptive use and past diaphragm use also remained protective for high-grade cervical dysplasia in these regression analyses. CONCLUSIONS: The data suggest that use of oral contraceptives (ever) and past diaphragm use are protective for high-grade cervical dysplasia among Hispanic and non-Hispanic white women in New Mexico. The clinic-based perspective of this research (versus population-based studies) may help explain some of these findings.

Incidence of plague associated with increased winter-spring precipitation in New Mexico.

Plague occurs episodically in many parts of the world, and some outbreaks appear to be related to increased abundance of rodents and other mammals that serve as hosts for vector fleas. Climate dynamics may influence the abundance of both fleas and mammals, thereby having an indirect effect on human plague incidence. An understanding of the relationship between climate and plague could be useful in predicting periods of increased risk of plague transmission. In this study, we used correlation analyses of 215 human cases of plague in relation to precipitation records from 1948 to 1996 in areas of New Mexico with history of human plague cases (38 cities, towns, and villages). We conducted analyses using 3 spatial scales: global (El Niño-Southern Oscillation Indices [SOI]); regional (pooled state-wide precipitation averages); and local (precipitation data from weather stations near plague case sites). We found that human plague cases in New Mexico occurred more frequently following winter-spring periods (October to May) with above-average precipitation (mean plague years = 113% of normal rain/ snowfall), resulting in 60% more cases of plague in humans following wet versus dry winter-spring periods. However, we obtained significant results at local level only; regional state-wide precipitation averages and SOI values exhibited no significant correlations to incidence of human plague cases. These results are consistent with our hypothesis of a trophic cascade in which increased winter-spring precipitation enhances small mammal food resource productivity (plants and insects), leading to an increase in the abundance of plague hosts. In addition, moister climate conditions may act to promote flea survival and reproduction, also enhancing plague transmission. Finally, the result that the number of human plague cases in New Mexico was positively associated with higher than normal winter-spring precipitation at a local scale can be used by physicians and public health personnel to identify and predict periods of increased risk of plague transmission to humans.

Small mammal survival and trapability in mark-recapture monitoring programs for hantavirus.

Following the 1993 hantavirus pulmonary syndrome (HPS) epidemic in the south-western United States, mammalogists and epidemiologists instituted long-term studies to monitor population density and prevalence of infection in rodents which constitute the reservoir for Sin Nombre virus (SNV). In this study, field techniques used in sampling small mammals for SNV infection were evaluated to determine if trapping and handling protocols were having significant effects on future trapability or mortality of animals. We compared rodent mark-recapture control plots, on which all rodents were simply measured, marked, and released on site, with experimental plots on which all animals were anesthetized with methoxyflurane, sampled for blood and saliva, measured, marked, and released. Blood samples were obtained from anesthetized animals on the experimental plots via a retro-orbital sinus puncture using a heparinized capillary tube. Dacron tipped oral swabs were used to collect buccal cells and saliva from the rodent's oral cavity. Field data were collected monthly from August 1994 to August 1996 at two sites in New Mexico (USA). Analyses were based on 3,661 captures of 1,513 individuals representing 21 species from three rodent families (Rodentia: Muridae, Heteromyidae, Sciuridae) and two species of rabbits (Lagomorpha: Leporidae). Overall, for most murid rodents (including five Peromyscus spp., Neotoma albigula, and Onychomys leucogaster) and one rabbit species (Sylvilagus floridanus), the handling/bleeding procedures had no significant effects on recapture rates or mortality. In contrast, several species of heteromyids (Dipodomys ordii and Perognathus flavus), one murid (Reithrodontomys megalotis) and one leporid (S. auduboni) suffered higher mortality rates, and heteromyid kangaroo rats (D. ordii and D. merriami) exhibited lower trapability as a result of the anesthesia and sampling procedures. In view of the overall non-significant influence of the sampling procedures on murid rodents, the anesthesia and blood/saliva sampling protocols described herein appear to be appropriate for hantavirus research, and may serve as a model for environmental monitoring of other zoonotic agents and their reservoirs.

An asymmetrical tonic neck reflex rating scale.

Although the asymmetrical tonic neck reflex (ATNR) is commonly used as one clinical assessment when evaluating children with suspected sensory integration deficits, maturational lags, or behavioral dysfunctions, observations are limited on the degree of this reflex in normal children at different age levels. A quantitative rating scale that indicates the degree of integration of the ATNR in normal first and third grade children is presented for purposes of comparison with the "suspect" child. A procedure for testing this reflex is described using the quadrupedal position, four sequences of lateral head rotation, and a rating scale consisting of four components. Using this ATNR rating scale, scores can be derived that could serve as a guide in determining whether the residual ATNR is comparable to that of normal subjects of the same age.

The asymmetrical tonic neck reflex in normal first and third grade children.

Diminished inhibition of the asymmetrical tonic neck reflux (ATNR) is frequently used as a clinical tool when evaluating children with maturational lags, sensory integration deficits, and learning and behavioral dysfunction. However, limited observations are available on the degree of integration of this primitive reflex in normal children at different age levels. In this study, 44 first grade and 36 third grade normal children were tested in the quadrupedal position by right and left lateral rotation of the head both actively and passively. Varying degrees of elbow flexion or muscle tone changes were elicited in all. First grade children displayed significantly more evidence of this reflex, especially when the head was rotated to the left. The results of this study indicate that frequent, visible muscle tone changes or elbow flexion to 30% in the arm ipsilateral to the skull position could be considered normal in children through the third grade.

Risk factors for cervical dysplasia in southwestern American Indian women: a pilot study.

Cervical cancer and cervical dysplasia occur at high rates among American Indian women in the southwestern United States. Few published data, however, have addressed risk factors for the development of cervical neoplasia among southwestern American Indian women. To investigate risk factors for cervical dysplasia in this population, we carried out a case-control pilot study focused on the effects of sexually transmitted diseases, sexual behavior, hygienic practices, cigarette use, contraceptive techniques, and diet in the development of cervical dysplasia. Although our pilot study lacked power to clearly identify risk factors for neoplasia, the data suggest that cervical papillomavirus infection (crude odds ratio 4.72, 95% confidence interval 1.62-14.11), vaginal deliveries (3.70, 0.69-20.04 for > 2 vaginal deliveries vs none), and current cigarette smoking (3.08, 0.50-24.15) were associated with dysplasia. These preliminary findings indicate that risk factors for dysplasia in American Indian women differ from risks which we have identified in southwestern Hispanic and non-Hispanic white women, and suggest the need for further investigation of ethnic differences in cervical disease development.

Rough approach, safe landing. Family members of people with HIV have support needs of their own.

AIDS: Claudette and Dave's lives turned upside down when their oldest son, Jon-Paul, told them that he had tested HIV-positive. Although he had many support systems available to him, Claudette and Dave soon learned that there were few resources available to them, as family members of someone living with HIV. Dave approached a seminary professor he knew and Claudette approached co-workers and friends. By letting others know of their needs very clearly, Claudette and Dave soon learned that others were available to help them and their family. Support included anything from encouraging notes and cards, to making dinner, to providing rides for Claudette to see her son. Opening up and asking for and offering help can teach invaluable lessons.^ieng

Panting thresholds of lizards. IV. The effect of dehydration on the panting threshold of Amphibolurus barbatus and Amphibolurus muricatus.

Amphibolurus barbatus which occupies arid and mesic habitats elevates its panting threshold with increasing loss of body water, thereby minimizing water loss at the expense of thermoregulatory effectiveness. Change in panting threshold is greatest up to losses of body water of 6-8% of hydrated weight, after which adjustment of the threshold is of lesser magnitude. Amphibolurus muricatus, a species restricted to the more mesic regions of Australia, does not show any change of panting threshold with progressive dehydration.

Influence of diminished respiratory surface area on survival of sea turtle embryos.

It has been suggested that fungal presence on sea turtle eggs may impede gas exchange. To investigate the influence of diminished gas exchange surface upon embryo survivorship, flatback (Natator depressus) and green (Chelonia mydas) eggs were painted with petroleum jelly. Variable proportions of the egg surface were covered, including both respiratory and nonrespiratory domains. Embryo survival varied with site inhibited, proportion of eggshell affected, and species of turtle. If fungi on the exterior of the eggshell are able to impede respiratory gas exchange, their presence on the upper hemisphere (primary gas exchange area in early incubation) will result in the highest embryo mortality. Large eggs are likely to demonstrate a higher survivorship than small eggs, due to their larger available respiratory area and/or to variation in weight or stage-specific embryonic metabolic demands. Interspecific differences in egg size may therefore be a contributory factor to observed mortality rate differences in the natural presence of fungi.

Statistical sensitivity for detection of spatial and temporal patterns in rodent population densities.

A long-term monitoring program begun 1 year after the epidemic of hantavirus pulmonary syndrome in the U.S. Southwest tracked rodent density changes through time and among sites and related these changes to hantavirus infection rates in various small-mammal reservoir species and human disease outbreaks. We assessed the statistical sensitivity of the program's field design and tested for potential biases in population estimates due to unintended deaths of rodents. Analyzing data from two sites in New Mexico from 1994 to 1998, we found that for many species of Peromyscus, Reithrodontomys, Neotoma, Dipodomys, and Perognathus, the monitoring program detected species-specific spatial and temporal differences in rodent densities; trap-related deaths did not significantly affect long-term population estimates. The program also detected a short-term increase in rodent densities in the winter of 1997-98, demonstrating its usefulness in identifying conditions conducive to increased risk for human disease.

Factors controlling the competition among rotational and vibrational energy transfer channels in glyoxal.

The state-to-state transfer of rotational and vibrational energy has been studied for S1 glyoxal (CHOCHO) in collisions with D2, N2, CO and C2H4 using crossed molecular beams. A laser is used to pump glyoxal seeded in He to its S1 zero point level with zero angular momentum about its top axis (K' = 0). The inelastic scattering to each of at least 26 S1 glyoxal rotational and rovibrational levels is monitored by dispersed S1-S0 fluorescence. Various collision partners are chosen to investigate the relative influences of reduced mass and the collision pair interaction potential on the competition among the energy transfer channels. When the data are combined with that obtained previously from other collision partners whose masses range from 2 to 84 amu, it is seen that the channel competition is controlled primarily by the kinematics of the collisional interaction. Variations in the intermolecular potential play strictly a secondary role.

Determinants of genital human papillomavirus infection among cytologically normal women attending the University of New Mexico student health center.

OBJECTIVES: To confirm the risk factors for genital human papillomavirus (HPV) infection. GOAL OF THIS STUDY: To investigate risk factors for HPV detection apart from the correlated risk factors for cervical neoplasia. STUDY DESIGN: Cervical human papillomavirus (HPV) DNA was assessed in 357 cytologically normal women attending the University of New Mexico student health center. Cervical swab samples were obtained for HPV DNA detection and typing using a PCR-based DNA amplification system. Possible determinants of cervical HPV were examined including age, ethnicity, history of sexually transmitted disease, oral contraceptive use, smoking, age at first intercourse, lifetime number of sex partners, marital status, and history of pregnancy. RESULTS: A 44.3% overall prevalence of cervical HPV was observed. On univariate analysis, factors associated with increasing HPV prevalence included higher lifetime number of sex partners and single marital status. After adjustment for potential confounding variables, we found that HPV prevalence increased with higher lifetime number of sexual partners. CONCLUSION: These findings, along with those from the companion reports in this issue of the journal, support the sexual route of transmission of the virus.

Sexually transmitted diseases and other risk factors for cervical dysplasia among southwestern Hispanic and non-Hispanic white women.

OBJECTIVE: To assess risk factors for high-grade cervical dysplasia among southwestern Hispanic and non-Hispanic white women. DESIGN: Clinic-based case-control study. SETTING: University-affiliated gynecology clinics. SUBJECTS: Cases were Hispanic and non-Hispanic white women with biopsy-proven high-grade cervical dysplasia (n = 201). Controls were Hispanic and non-Hispanic white women from the same clinics with normal cervical epithelium (n = 337). METHODS: Study design included interviews focused on histories of sexually transmitted diseases, sexual behavior, reproductive histories, hygienic practices, contraceptive use, cigarette smoking, and diet. Laboratory studies included bacterial and protozoal cultures of the cervix; hybridization tests to identify human papillomavirus (HPV) genome with commercial (ViraPap and ViraType) and polymerase chain reaction-based assays; and serum antibody tests for herpes simplex virus, Chlamydia trachomatis, syphilis, hepatitis B, and hepatitis C. RESULTS: For both ethnic groups combined, after adjustment for ethnicity, age, and sexual behavior, the strongest risks for cervical dysplasia were associated with cervical HPV infection as identified by ViraPap (odds ratio [OR], 12.8; 95% confidence interval [CI], 8.2 to 20.0) or with polymerase chain reaction (OR, 20.8; 95% CI, 10.8 to 40.2). Other factors associated with dysplasia included cigarette smoking at the time of diagnosis (OR, 1.8; 95% CI, 1.2 to 2.8); low income (OR, 2.2; 95% CI, 1.2 to 4.0); low educational level (OR, 6.2; 95% CI, 3.4 to 11.1); history of any sexually transmitted disease (OR, 1.9; 95% CI, 1.3 to 2.7); and seroprevalence of antibodies to hepatitis B (OR, 1.8; 95% CI, 0.9 to 3.5). For Hispanic women, HPV 16/18 identified by ViraType was strongly associated with cervical dysplasia (OR, 171.0; 95% CI, 22.8 to 1280.5). Antibodies to herpes simplex virus type 2 were not associated with dysplasia in Hispanic women but were significantly associated with dysplasia among non-Hispanic whites. Risks associated with cigarette smoking also varied by ethnic group. CONCLUSIONS: The strongest risk factor associated with high-grade cervical dysplasia among clinic attendees was HPV infection. Although most of the risk factors we examined showed similar associations for dysplasia for both ethnic groups, our data suggest that several different risk factors may be relevant to the development of cervical dysplasia in Hispanics compared with non-Hispanic whites who attend the same clinics.