Chromium propionate supplementation during the peripartum period interacts with starch source fed postpartum: Production responses during the immediate postpartum and carryover periods.

Forty-eight multiparous cows were used in a randomized complete block design experiment with a 2×2 factorial arrangement of treatments to determine the interaction between chromium propionate (CrPr) supplementation and sources of corn varying in ruminal starch fermentability on production responses during the postpartum (PP) and carryover periods. During the peripartum period (28d before expected parturition until 28d PP), diets were top-dressed (20g/d) with either CrPr (KemTRACE Chromium Propionate, Kemin Industries, Des Moines, IA; 8mg of Cr/cow per day) or control (Con; ground corn). At parturition, cows were randomly assigned to corn treatment within CrPr and Con treatments: dry corn (DC) or high-moisture corn (HMC). Treatment combinations (CrPr/DC, CrPr/HMC, Con/DC, and Con/HMC) were fed from parturition until 28d PP (treatment period). Cows were fed a common diet to evaluate potential carryover effects of the treatment diets from 29 to 84d PP (carryover period). The CrPr and corn treatments interacted over time to affect yield of 3.5% fat-corrected milk (FCM) during both the treatment and carryover periods. The CrPr/HMC treatment combination tended to increase FCM compared with Con/DC and Con/HMC by 28d PP (57.4 vs. 48.6 and 48.5kg/d, respectively) and increased FCM compared with Con/DC by 42d PP (59.2 vs. 44.8kg/d). The CrPr tended to increase milk yield (55.4 vs. 51.9kg/d) regardless of corn source during the carryover period after treatment ceased. Daily and cumulative DMI were not affected by treatment during the PP period, but CrPr and corn treatments interacted over time to affect daily DMI during the carryover period; DMI was generally higher for CrPr/HMC, lower for Con/DC, and intermediate for CrPr/DC and Con/HMC from 29 to 84d PP. Supplementation of CrPr throughout the peripartum period interacted with starch source in PP diets over time to affect production responses that were sustained after treatment application ceased.

Agricultural food subsidies, migratory connectivity and large-scale disturbance in arctic coastal systems: a case study.

An allochthonous input can modify trophic relationships, by providing an external resource that is normally limiting within a system. The subsidy may not only elicit a growth response of the primary producers via a bottom-up effect, but it also may lead to runaway herbivore growth in the absence of increased predation. If the consumer is migratory and predation is similarly dampened in the alternative system, the increased numbers may produce a top-down cascade of direct and indirect effects on an ecosystem that may be a great distance from the source of the subsidy. In an extreme case, it can lead to a catastrophic shift in ecosystem functioning as a result of biotic exploitation that produces an alternative stable state. The loss of resilience is particularly sensitive to herbivore density which can result in two different outcomes to the vegetation on which the consumer feeds. Over-compensatory growth of above-ground biomass gives way to sward destruction and near irreversible changes in soil properties as density of a herbivore increases. A striking temporal asymmetry exists between a reduction in the consumer population and recovery of damaged vegetation and degraded soils.

Factors associated with prevalent hepatitis C: differences among young adult injection drug users in lower and upper Manhattan, New York City.

OBJECTIVES: This study examined correlates of prevalent hepatitis C virus (HCV) infection among young adult injection drug users in 2 neighborhoods in New York City. METHODS: Injection drug users aged 18 to 29 years were street recruited from the Lower East Side and Harlem. Participants were interviewed about drug use and sex practices; venipuncture was performed for hepatitis B virus (HBV), HCV, and HIV serologies. RESULTS: In both sites, testing positive for HCV antibody (anti-HCV) was associated with having injected for more than 3 years. Additionally, HCV infection was positively associated with injecting with someone known to have had hepatitis (but the association was significant only in the Lower East Side) and with sharing cotton (but the association was statistically significant only in Harlem). Being in drug treatment and older than 24 years were associated with HCV in the Lower East Side but not in Harlem. Receiving money for sex was associated with anti-HCV positivity in Harlem but not in the Lower East Side. CONCLUSIONS: Several differences in factors associated with prevalent HCV infection existed among 2 populations of young injection drug users from the same city. Indirect transmission of HCV may occur.

Behavioral risk reduction in a declining HIV epidemic: injection drug users in New York City, 1990-1997.

OBJECTIVES: This study assessed trends in HIV risk behaviors among injection drug users in New York City from 1990 to 1997. METHODS: Injection drug users were recruited continuously from a large drug detoxification treatment program (N = 2588) and a research storefront located in a high-drug-use area (N = 2701). Informed consent was obtained, and a trained interviewer administered a structured interview covering sociodemographics, drug use history, HIV risk behavior, and participation in syringe exchange. RESULTS: Trends were assessed for 5 risk behaviors in the 6-month period before the interview. The 3 injection risk behaviors declined significantly over time at each site (all P < .01). When data were pooled across sites, all 5 risk behaviors declined significantly over time (all P < .01). Participation in syringe exchange programs and in HIV counseling and testing increased greatly from 1990 to 1997. CONCLUSIONS: The continuing risk reduction among injection drug users indicates a "declining phase" in the large HIV epidemic in New York City. HIV prevention programs appear to be making an important contribution to the declining phase.

Geographic proximity, policy and utilization of syringe exchange programmes.

The objective of the research was to assess the effects of geographic proximity on the utilization of syringe exchange among injection drug users (IDUs) in New York City. Between 1994 and 1996, 805 IDUs were interviewed with a structured questionnaire. Geographic proximity was defined as living within a ten-minute walk. Eighty-one per cent of IDUs who lived close typically used a syringe exchange compared to 59% of those who lived further away. In multiple logistic regression analysis, those who lived close remained (adjusted odds ratio of 2.89; 95% CI 2.06 to 4.06, p = 0.001) more likely to use syringe exchange. Those who lived close were less likely to have engaged in receptive syringe sharing at last injection (adjusted odds ratio = 0.45, 95% CI 0.24 to 0.86, p = 0.015). In conclusion, locating exchange services in areas convenient to large numbers of IDUs may be critical for prevention of HIV infection.

Similarities and differences by race/ethnicity in changes of HIV seroprevalence and related behaviors among drug injectors in New York City, 1991-1996.

OBJECTIVE: To measure differences and similarities in the prevalence of HIV infection and of related risk and protective behaviors among New York City black, white, and Hispanic drug injectors during a period of decreasing HIV prevalence. METHODS: Drug injectors were interviewed at a drug detoxification clinic and a research storefront in New York City from 1990 to 1996. All subjects had injected drugs within the last six months. Phlebotomy for HIV testing was conducted after pretest counseling. Analysis compares the first half (period) of this recruitment interval with the second half. RESULTS: HIV seroprevalence declined among each racial/ethnic group. In each period, white drug injectors were significantly less likely to be infected than either blacks or Hispanics. Similar declines were found in separate analyses by gender, length of time since first injection, and by recruitment site. After adjustment for changes in sample composition over time, blacks and Hispanics remained significantly more likely to be infected than whites. Interactions indicate that the decline may be greatest among Hispanics and slowest among blacks. A wide variety of risk behaviors declined in each racial/ethnic group; and syringe exchange use increased in each group. Few respondents reported injecting with members of a different racial group at their last injection event. CONCLUSIONS: HIV prevalence and risk behaviors seem to be falling among each racial/ethnic group of drug injectors. Black and Hispanic injectors continue to be more likely to be infected. Declining prevalence among whites poses some risk of politically based decisions to reduce prevention efforts. Overall, these results show that risk reduction can be successful among all racial/ethnic groups of drug injectors and suggest that continued risk reduction programs may be able to attain further declines in infection rates in each group.

Safety recommendations for laser pointers.

The use of laser diode pointers that operate in the visible radiation region (400-760 nm) is becoming widespread. These pointers are intended for use by educators while presenting talks in the classroom or at conventions and meetings. They are also useful in any situation where one needs to point out special items during any instructive situation. The pointers can be purchased in novelty stores, mail-order magazines, office supply stores, common electronic stores, and over the internet. The power omitted by these laser pointers ranges from 1 to 5 mW. The potential for hazard with laser pointers is generally considered to be limited to the unprotected eyes of individuals who might be exposed by a direct beam (intrabeam viewing). No skin hazard usually exists. There are, however, even more powerful laser pointers now appearing. The units are imported into the U.S. often without proper manufacturer certification or labeling. The potential for hazards with these devices is not well understood by the general public and workers, and numerous exposure incidents have been recorded by the authors. Users of these products need to be alerted to the potential hazards and be encouraged to follow appropriate safety recommendations. These factors are discussed and safety recommendations for laser pointers are presented.

Sharing and archiving data is fundamental to scientific progress.

The persuasive argument for sharing and archiving data is that scientists must build on the shoulders of other scientists, that science is cumulative and replicative, and that science must be open. Sharing and archiving data are just a small part of all that is implied by that principle, but it is inextricably part of our obligation as social and behavioral scientists to conduct our work in the open. Only then can others see and understand what we did, and only then will someone have a chance to confirm that we were right, or to prove that we were wrong. Moreover, data archiving and sharing create opportunities for addressing questions not envisioned by the initial investigators. Indeed, by supplementing or pooling archived data, new and original data sets can be created that permit analyses well beyond the purpose or scope of the initial data collection. Of course, the creativity and labor of initial investigators should be protected, and the privacy of research participants must be safeguarded. These protections and safeguards, however, are not antithetical to data archiving and sharing. They simply raise questions about when and how data archiving and sharing should take place. In our view, the benefits of properly archived and shared data for outweigh the potential for harm. As indicated above, this is a perspective shared by several funding agencies of behavioral and social research, including the NIA.

The biologic effects of C225, a chimeric monoclonal antibody to the EGFR, on human prostate carcinoma.

For prostate cancer, a correlation exists between overexpression of the epidermal growth factor receptor (EGFR) and poor clinical prognosis. In addition, late-stage metastatic disease is characterized by a change from a paracrine to an autocrine mode of expression for TGF-alpha, the ligand for the EGFR. These observations suggest that activation of the EGFR may be important for the growth of prostatic carcinoma in situ, and blockade of the receptor-ligand interaction may offer a means of therapeutic intervention for this disease. We describe the biologic effects of a chimeric anti-EGFR monoclonal antibody, C225, on several human prostate tumor cell lines in culture and the tumor inhibitory properties of the antibody for the treatment of human prostate carcinoma xenografts in nude mice. In vitro analysis of the EGFR from androgen-responsive and independent prostatic carcinoma cell lines revealed that C225 blocked EGF-induced receptor activation and induced internalization of the receptor. In vivo, a treatment regimen of C225 alone or antibody plus doxorubicin significantly inhibited tumor progression of well-established DU145 and PC-3 xenografts in nude mice. These results suggest that C225 may have utility for the treatment of human prostate carcinoma in a clinical setting.

Genetic variation for resistance to chlorpyrifos in Drosophila melanogaster (Diptera: Drosophilidae) infesting grapes in Israel.

Five species of drosophilid flies were observed breeding in grapes growing in Israel; of these, 2 species, Drosophila melanogaster (Meigen) and D. simulans Sturtevant, are major pests. Natural populations of both species were sampled and tested for resistance to chlorpyrifos; the 2 more intensively sampled populations were D. melanogaster in commercial vineyards. One vineyard had been treated repeatedly with chlorpyrifos to control this secondary pest species; the other had never been treated with an organophosphorus compound. The LC50 to chlorpyrifos of a genetically heterogeneous line of D. melanogaster from the exposed population (Be'er Tuvia) was 99 ng/cm2, and the LC50 of a corresponding line from the unexposed population (Sde Eliahu) was 52 ng/cm2; the wild-caught lines were much more resistant than a laboratory strain, Canton-S, whose LC50 was 0.25 ng/cm2. Genetic variance for resistance existed in both natural populations but realized heritability did not differ significantly between the populations. In crosses between a highly resistant strain and several sensitive laboratory strains of D. melanogaster, resistance was dominant. A resistance factor was mapped to a locus on chromosome 2 (approximately 2-72).

Effective Population Size and Lifetime Reproductive Success.

The mean and variance of lifetime reproductive success, ELRS and VLRS , influence the ratio of effective to census population size, Ne /Nc . Because the complete data needed to calculate ELRS and VLRS are seldom available, we provide alternatives for estimating Ne /Nc from incomplete data. These estimates should be useful to conservation biologists trying to compute the effective size of a censused population. An analytical approach makes assumptions regarding the process influencing offspring survival. We provide a method for examining the validity of those assumptions and show that particular violations can result in either over- or underestimates. When the assumptions are violated or when more data are available, we suggest estimating Ne /Nc using computer simulations of models based on individuals. We examine how such simulations can be used to estimate Ne /Nc using an individual-based model for Lesser Snow Geese (Anser caerulescens). We demonstrate that such estimates can be biased unless the simulations are based on complete cohorts and samples of known age. We show that because the estimate of Ne /Nc depends on the stage of the reproductive cycle used as a point of reference in the model, the census population size Nc must be based on the same stage to provide unbiased estimates of Ne . Tamaño poblacional efectivo y el éxito reproductivo vitalicio.

Resumen: La media y la varianza del éxito reproductivo vitalicio (ELRS y VLRS ) influencía el cociente entre tamaño poblacional efectivo y el tamaño censal Ne /Nc . Dado que los datos completos necesarios para calcular ELRS y VLRS están raramente disponibles, nosotros proveemos alternativas para estimar Ne /Nc a partir de datos incompletos. Estas estimaciones deberían ser útiles para los biólogos de la conservación que tratan de computar el tamaño efectivo de una población censada. Una aproximación analítica utiliza supuestos acerca del proceso que influencía la supervivencia de la progenie. Nosotros proveemos de un método para examinar la validez de esos supuestos y mostramos violaciones particulares que resultan en sobreestimaciones o subestimaciones. Cuando los supuestos son violados o cuando más datos estan disponibles, nosostros sugerimos estimar Ne /Nc utilizando simulaciones de modelos basados en individuos. Examinamos como tales simulaciones pueden ser usadas para estimar Ne /Nc utilizando un modelo basado en individuos para el ganso (Anser caerulescens). Demostramos que tales estimaciones pueden estar sesgadas a menos que las simulaciones esten basadas en cohortes completas y muestras de edades conocidas. Mostramos que dado que la estimación de Ne /Nc depende del estado del ciclo reproductivo usado como punto de referencia en el modelo, el tamaño poblacional censal (Nc ) debe estar basado en el mismo estado a efecto de proveer estimaciones de Ne no sesgadas.

Variance of lifetime reproductive success: estimation based on demographic data.

Variance of lifetime reproductive success is not a well-defined parameter; it is a function of the way a life cycle is defined. Therefore, comparisons of such variance across studies and taxa will only be valid if the life cycles employed are complete (i.e., an entire generation), precisely defined (e.g., egg to egg or adult to adult), and identical. Given a well-defined life cycle, we present methods for obtaining estimates of the variance of lifetime reproductive success among individuals using demographic data. The estimates are based on the assumptions of no selection and negligible covariance between life span and reproductive effort. The techniques can be used to investigate the effects of alternate life histories on the distribution of reproductive success in a population, as well as to obtain estimates of effective population size. They may also provide a null model for investigations of selection. Some theoretical and empirical results are presented. A method for obtaining confidence intervals for the estimates is described.

Fitness consequences of egg-size variation in the lesser snow goose.

We investigated the relationship between eggsize variation and (a) egg hatching success, (b) chick survival to fledging and recruitment, and (c) adult female survival, over 12 years in the lesser snow goose (Anser caerulescens caerulescens). By comparing the means and variances of egg size for successful and unsuccessful eggs, our aim was to assess the relative fitness of eggs of different sizes and to determine the type of selection operating on egg size in this species. As both egg size and reproductive success vary with age in the lesser snow goose we controlled for the effects of female age. Egg-size variation is very marked in this population, varying by up to 52% for eggs hatching successfully. However, there was no relationship between egg size and post-hatching survival of goslings to fledging or recruitment, either within or between broods, pooling across years. Egg size varied significantly between successful and unsuccessful clutches in only 2 of 33 individual year comparisons. First-laid eggs surviving to onset of incubation, and eggs hatching successfully, were on average larger than unsuccessful eggs, but this was probably due to the confounding effects of female age-specific and sequence-specific egg survival. Variance of egg size differed significantly between successful and unsuccessful eggs in only 3 of 24, and 0 of 21, individual year comparisons for pre- and post-hatching survival respectively. We therefore found little evidence for a relationship between egg-size variation and offspring fitness, or for strong directional, normalising or diversifying selection operating on egg size, in the lesser snow goose. In addition, there was only weak support for the hypothesis that egg-size variation is maintained by temporal variation in selection pressure (sensu Ankney and Bisset 1973). It is likely that egg-size variation represents the pleiotropic expression of alleles affecting more general physiological or metabolic processes. While this does not rule out the existence of alleles with more direct effects on egg size we suggest that their contribution to heritable egg size is small.

Environmental change and the cost of philopatry: an example in the lesser snow goose.

The consequences of philopatric and dispersal behaviours under changing environmental conditions were examined using data from the colony of Lesser Snow Geese (Anser caerulescens caerulescens) breeding at La Pérouse Bay, Manitoba, Canada. In response to increased population size and decreased food abundance over time, increasing numbers of family groups have been dispersing from the traditional feeding areas. Goslings from dispersed broods were significantly heavier (7.3%), and had longer culmens (3.1%), head lengths (2.6%) and marginally longer tarsi (1.9%) on average than goslings that remained within La Pérouse Bay itself. These differences were consistent in each of 5 years. There was no evidence that the larger size of dispersed goslings was due to either a tendency for larger adults to disperse to alternative sites, or increased mortality of smaller goslings among dispersed broods. The most likely cause for the larger size of goslings from dispersed broods was the significantly greater per capita availability of the preferred salt-marsh forage species at non-traditional brood-rearing areas. The larger goslings in non-traditional feeding areas showed significantly higher firstyear survival, suggesting that the use of deteriorating traditional feeding areas may currently be maladaptive in this population.

Mucin production by human colonic carcinoma cells correlates with their metastatic potential in animal models of colon cancer metastasis.

Patients with mucinous colorectal cancers characteristically present with advanced disease, however, the relationship between mucin production by colon cancer cells and their metastatic potential remains unclear. We therefore sought to define the relationship between mucin production by human colon cancer cells and metastatic ability by employing animal models of colon cancer metastasis. LS LiM 6, a colon carcinoma cell line with high liver metastasizing ability during cecal growth in nude mice produced twofold more metabolically labeled intracellular mucin and secreted four- to fivefold more mucin into the culture medium compared to poorly metastatic parental line LS174T. This was accompanied by a similar elevation in poly(A)+ RNA detected by blot hybridization with a human intestinal mucin cDNA probe, and increases in mucin core carbohydrate antigens determined immunohistochemically. Variants of LS174T selected for high (HM 7) or low (LM 12) mucin synthesizing capacity also yielded metastases after cecal growth and colonized the liver after splenic-portal injection in proportion to their ability to produce mucin. Inhibition of mucin glycosylation by the arylglycoside benzyl-alpha-N-acetyl-galactosamine greatly reduced liver colonization after splenic-portal injection of the tumor cells. These data suggest that mucin production by human colon cancer cells correlates with their metastatic potential and affects their ability to colonize the liver in experimental model systems.

Cell surface sialoprotein alterations in metastatic murine colon cancer cell lines selected in an animal model for colon cancer metastasis.

Alterations in cell surface proteins and glycoproteins may play a key role in determining the metastatic behavior of tumor cells. The cell surface proteins of a series of related murine colon cancer cells selected in an animal model for colon cancer metastasis (R. S. Bresalier et al., Cancer Res., 47: 1398-1406, 1987) were therefore compared by a variety of biochemical methods. Lactoperoxidase-catalyzed iodination of cell surface proteins followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis demonstrated quantitative and qualitative differences in the cell surface protein profiles of parental cell line 51B (low metastatic potential) and its metastatic derivatives 51B LiM 5 and 51B LiM 6. Labeling of sialic acid-containing proteins suggested that, in the case of at least four of these proteins (Mr 170,000, 120,000, 95,000, and 55,000), this represented an increase in radioactive labeling of sialoglycoproteins from the metastatic lines. Affinity chromatography of solubilized 125I-labeled cell membrane proteins revealed a 2- to 3-fold increase in wheat germ agglutinin and Sambucus nigra lectin binding associated with the metastatic lines, compared to the poorly metastatic parent. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of material eluted from these columns demonstrated enhancement of proteins from the metastatic cells corresponding in molecular weight to the previously identified major sialoglycoproteins. Neuraminidase-releasable membrane-associated sialic acid and sialyltransferase activities were 2- to 3-fold higher in the metastatic cell lines compared to the parental line. Liver colonization after intrasplenic injection of the various lines into syngeneic mice was dramatically reduced by prior removal of cell surface sialic acid. Immunohistochemical staining of primary and metastatic tumors formed after cecal injection of parental 51B suggested selective metastasis by wheat germ agglutinin-binding tumor cells. These results further support the concept that cell membrane sialylation is important in determining the metastatic potential of cancer cells.

Optical radiation hazards of laser welding processes. Part II: CO2 laser.

There has been an extensive growth within the last five years in the use of high-powered lasers in various metalworking processes. The two types of lasers used most frequently for laser welding/cutting processes are the Neodymium-yttrium-aluminum-garnet (Nd:YAG) and the carbon dioxide (CO2) systems. When such lasers are operated in an open beam configuration, they are designated as a Class IV laser system. Class IV lasers are high-powered lasers that may present an eye and skin hazard under most common exposure conditions, either directly or when the beam has been diffusely scattered. Significant control measures are required for unenclosed (open beam), Class IV laser systems since workers may be exposed to scattered or reflected beams during the operation, maintenance, and service of these lasers. In addition to ocular and/or skin exposure hazards, such lasers also may present a multitude of nonlaser beam occupational concerns. Radiant energy measurements are reported for both the scattered laser radiation and the plasma-related plume radiations released during typical high-powered CO2 laser-target interactions. In addition, the application of the nominal hazard zone (NHZ) and other control measures also are discussed with special emphasis on Class IV industrial CO2 laser systems.

Studies of sibling Drosophila species from Laguna Verde, Veracruz, Mexico: I. Species frequencies, viability, desiccation resistance, and vagility.

The sibling species Drosophila melanogaster and D. simulans were collected at Laguna Verde, Veracruz, Mexico. D. melanogaster was found in significantly greater frequency than was D. simulans. Ten isofemale lines of each species were tested for egg to adult viability, desiccation resistance, and vagility. D. melanogaster surpassed D. simulans in all three characteristics. The findings are discussed with reference to the climatic conditions at Laguna Verde and the expected effect of such an environment on the relative frequencies of these species. The dichotomous results in regard to desiccation resistance and vagility that were observed between recently collected D. melanogaster and the Oregon-R laboratory stock of that species are also discussed.

Nuclear power plants and natural populations of Mexican Drosophila.

With the worldwide proliferation of nuclear power plants has come the need to study the biological effects of the operation of the reactors on surrounding populations. We have begun a long-term study of the sibling species Drosophila melanogaster and D. simulans in the area of Laguna Verde in the state of Veracruz in Mexico. Laguna Verde, on the Gulf of Mexico about 75 km north of the city of Veracruz, is the location of the country's first nuclear power plant. This plant has not yet gone "on-line." The species have been collected from two sites, one of which is south of the reactor and is in the path of the prevailing north to south wind flow. The other collecting site is west of the plant. The species are being studied for the following: species frequency, desiccation resistance, vagility, proportion of larvae pupating, pupation height, and egg to adult survival after irradiation. To date we have noted both spatial and seasonal differences in a number of these characteristics. The information being gathered will serve as base-line data for monitoring the future operation of the nuclear power plant.