Atomic-scale electron microscopy at ambient pressure.

We demonstrate a novel nanoreactor for performing atomic-resolution environmental transmission electron microscopy (ETEM) of nanostructured materials during exposure to gases at ambient pressures and elevated temperatures. The nanoreactor is a microelectromechanical system (MEMS) and is functionalized with a micrometer-sized gas-flow channel, electron-transparent windows and a heating device. It fits into the tip of a dedicated sample holder that can be used in a normal CM microscope of Philips/FEI Company. The nanoreactor performance was demonstrated by ETEM imaging of a Cu/ZnO catalyst for methanol synthesis during exposure to hydrogen. Specifically, the nanoreactor facilitated the direct observation of Cu nanocrystal growth and mobility on a sub-second time scale during heating to 500 degrees C and exposure to 1.2 bar of H(2). For the same gas reaction environment, ETEM images show atomic lattice fringes in the Cu nanocrystals with spacing of 0.18 nm, attesting the spatial resolution limit of the system. The nanoreactor concept opens up new possibilities for in situ studies of nanomaterials and the ways they interact with their ambient working environment in diverse areas, such as heterogeneous catalysis, electrochemistry, nanofabrication, materials science and biology.

Solventogenic enzymes of Clostridium acetobutylicum: catalytic properties, genetic organization, and transcriptional regulation.

The enzymes acetoacetate decarboxylase and coenzyme A transferase catalyse acetone production from acetoacetyl-CoA in Clostridium acetobutylicum. The adc gene encoding the former enzyme is organized in a monocistronic operon, while the ctf genes form a common transcription unit with the gene (adhE) encoding a probable polyfunctional aldehyde/alcohol dehydrogenase. This genetic arrangement could reflect physiological requirements at the onset of solventogenesis. In addition to AdhE, two butanol dehydrogenase isozymes and a thiolase are involved in butanol synthesis. RNA analyses showed a sequential order of induction for the different butanol dehydrogenase genes, indicating an in vivo function of BdhI in low level butanol formation. The physiological roles of AdhE and BdhII most likely involve high level butanol formation, with AdhE being responsible for the onset of solventogenesis and BdhII ensuring continued butanol production. Addition of methyl viologen results in artificially induced butanol synthesis which seems to be mediated by a still unknown set of enzymes. Although the signal that triggers the shift to solventogenesis has not yet been elucidated, recent investigations suggest a possible function of DNA supercoiling as a transcriptional sensor of the respective environmental stimuli.

Cost analysis and facility reimbursement in the long-term health care industry.

This article examines costs and develops a system of prospective reimbursement for the industry committed to long-term health care. Together with estimates of average cost functions--for purposes of determining those factors affecting the costs of long-term health care, the author examines in depth the cost effects of patient mix and facility quality. Policy implications are indicated. The article estimates cost savings and predicted improvements in facility performance resulting from adoption of a prospective reimbursement system.

Differentiation of the gonads and initiation of mammary gland and scrotum development in the brushtail possum Trichosurus vulpecula (Marsupialia).

The first appearance of the mammary and scrotal primordia and the sexual differentiation of the gonads of the brushtail possum, Trichosurus vulpecula, are described. Primordial germ cells were first observed, in fetuses of 7.5 mm crown-rump length, in the gonadal ridges and migrating up the dorsal mesentery. Mammary primordia were first observed in fetuses of 11 mm, and scrotal primordia in those of 12 mm crown-rump length. These structures were diagnostic of female and male brushtail possums respectively. Processus vaginales and gubernacula showed sexual dimorphism, being better developed and appearing earlier in males than in females. Sexual differentiation of the gonads occurred after the appearance of mammary and scrotal primordia, the testes being first recognisable in a 14.5-mm fetus and the ovaries postnatally. Birth occurred between the stages of 14 and 15 mm crown-rump length. These observations appear to indicate that the development of mammary and scrotal primordia are not under gonadal hormonal control, but under direct genetic control, as suggested for the tammar wallaby by previous authors.

Postnatal development of the reproductive system in the grey short-tailed opossum, Monodelphis domestica.

Postnatal phenotypic sex differentiation has been investigated in a laboratory marsupial, Monodelphis domestica, as part of a larger study to resolve apparent discrepancies between eutherian and marsupial mammals. These include the formation of sex-specific structures in marsupials prior to gonadal differentiation and the retention in both sexes of structures which are sex-specific in eutherians. The time-course and nature of differentiation was investigated in 131 specimens ranging in age from the day of birth to 56 days. Patent wolffian ducts extend to the urogenital sinus in both sexes at birth, while müllerian ducts are identified on day 1 and grow in a cranio-caudal direction to reach the urogenital sinus on day 6. The male müllerian duct shows signs of regression at its cranial end on day 10 and throughout its length on day 12; its lumen has completely disappeared by day 15. By this time the epididymis and vas deferens have developed from the wolffian duct; their histological differentiation occurs between days 26 and 56. Prostatic buds are identifiable in tissue surrounding the male urethra on day 14. In the female, the wolffian duct is larger than the müllerian duct until day 14; thereafter the wolffian duct begins to regress at its cranial end, disappearing by day 17, whereas the müllerian duct begins to enlarge, converging with its fellow at the urogenital sinus by day 19. Lateral vaginae, vaginal culs-de-sac, uteri and oviducts have differentiated from the müllerian ducts by day 25. Gonads of both sexes are elongated in shape at birth, attached along the medial aspect of the large mesonephroi in the abdominal cavity. However, from day 3 onwards the testis becomes more rounded than the ovary. Degeneration of the male mesonephros begins about day 10 and is almost completed by day 19; the female mesonephros is still relatively large at day 14 though it too has almost disappeared by day 19. By postnatal day 13 the abdominal phase of testis descent is underway and the inguinal phase begins at day 15. Testes have reached the scrotal sac by day 24 and achieve their final position at the base of the scrotum by day 28. In summary, postnatal reproductive tract development and gonadal descent has been examined in this important biomedical model, where differentiation of the wolffian and müllerian ducts takes place after gonadal differentiation, according to the normal eutherian pattern.

The role of androgens in development of the scrotum of the grey short-tailed Brazilian opossum ( Monodelphis domestica).

In eutherian mammals, sex differentiation is initiated by expression of the testis-determining gene on the Y chromosome. Subsequent phenotypic development of the reproductive tract and genitalia depends on the production of hormones by the differentiated testis. In marsupials the mechanisms of phenotypic development may vary from this pattern, as differentiation of the scrotal primordia has been shown to occur before that of the gonad. Thus, the development of the scrotum in the marsupial has been regarded as an androgen-independent process. We have sought to clarify the ontogeny of scrotal development and the appearance of androgen receptor immunoreactivity by examining Monodelphis domesticaembryos/pups from 1 day prior to birth until 2 days after birth. We have also used immunocytochemistry to determine the expression of the key steroidogenic enzyme 3beta-hydroxysteroid dehydrogenase as an indicator of when the developing gonad may be capable of synthesizing androgens. Expression of this enzyme was first detected in the gonads and adrenals of both sexes 1 day prior to birth and before the appearance of scrotal bulges. Androgen receptor immunoreactivity was detected in the scrotal anlagen of male opossum pups as early as 1 day following birth. This finding is significantly earlier than previous reports and coincides with the appearance 1 day after birth of distinct scrotal bulges. Androgen receptor immunoreactivity was also observed in the genital tubercles of male pups, but not female pups, 2 days after birth. These results suggest that androgens may play an important role in the development of the male genitalia at a much earlier stage than that indicated by previously published work and that scrotal development in this species may not be androgen-independent.

Mammalian oocyte organelles with special reference to pleomorphic mitochondria and vacuole formation in marsupials.

Marsupial oocytes are larger and have a thinner zona than eutherian oocytes; and the ooplasm becomes almost completely filled with empty-looking vacuoles the contents of which have, so far, defied histochemical analysis. In the opossum, Monodelphis domestica, apart from orthodox mitochondria, a 'hooded' form is found occasionally in young primary oocytes, and a novel 'spiked' form-which is very elongate and has longitudinally-running filaments attached to the outer membrane--is found in mature oocytes. On the genesis of the ooplasmic vacuoles in mammals, information is available only for two marsupials. In Monodelphis, the vacuoles originate from endoplasmic, endocytotic and Golgi vesicles which generate multivesicular bodies; these give rise to the vacuoles. For the bandicoot, Isoodon macrourus, evidence is presented for the formation of the vacuoles from enlarged, transformed mitochondria which undergo a complex evolution during development. Primordial oocytes of Isoodon contain three ooplasmic localizations--a paranuclear complex, a vesicle microtubule complex and an aggregate of tubular cistenae-which have not been described for other mammalian oocytes. The origin, fate and function of these organelle localizations is unknown. In this paper, problems with respect to the definition of 'yolk' are described and the extent of our ignorance concerning oocyte organelles is discussed.

Culture of preantral ovarian follicles in the grey, short-tailed opossum, Monodelphis domestica.

A culture system designed to support the development of individual preantral mouse ovarian follicles has been employed to study follicle growth in the New World marsupial species Monodelphis domestica. Preantral follicles were isolated mechanically and cultured individually in microdrops under oil. Preliminary results indicate that follicle growth was positively correlated to the concentration of follicle-stimulating hormone (FSH) provided, with 1.0-1.5 IU FSH mL-1 producing the best results. Incubation at the body temperature of M. domestica (33 degrees C) was found to be preferable to that at 37 degrees C. The culture system was able to support follicle growth; however, despite follicles exceeding the size when antrum formation occurs in vivo, they remained preantral.

Comparing the economically advantaged and the pension elite: 1980 census profiles.

The number of economically advantaged retirees has grown rapidly since World War II. About 50% of retired individuals and 40% of retired households in the U.S. in 1980 had family income of more than double the poverty level. Economically advantaged retired households are most often headed by married, noncentral-city homeowners who show residential stability. They tend to have multiple income sources, some with income from at least three sources (the pension elite).

The impact of quality on cost in the provision of long-term care.

Regulatory and reimbursement policies in the health care industry have generally been developed on the assumption that a trade-off exists between quality enhancement and cost control. In this study of 494 proprietary, nonprofit, and government nursing home facilities in New York State, I examined the relationship between quality and costs while controlling for facility characteristics and resident characteristics. I found that although the capital-intensive aspects of patient care quality make a significant impact on costs, the labor-intensive aspects of patient care quality do not. I discuss the policy implications of these findings.

Further observations on the potoroo (Potorous tridactylus) in captivity.

The maintenance and breeding performance of potoroos in captivity over a 7-year period is described. By removing offspring from the pouch and allowing 29 days for completion of embryonic development and birth to occur, pouch young of known ages can be obtained.

An examination of total charges in the long-term health care industry.

A significant amount of work relating to long-term health care costs has appeared in the literature. Although shortcomings exist, there is at least some understanding of the relationships underlying costs. The subject of charges for long-term health care, however, has essentially been ignored in the literature to date. The purpose of this study was to gain an initial understanding of those factors underlying differences in charges per resident. The study used descriptive data from the 1977 National Nursing Home Survey and regression analysis to examine the relative effects of three sets of characteristics on charges per resident: characteristics of the facility, characteristics relating to the resident's medical needs, and characteristics relating to the socioeconomic status of the resident.

Contextual factors and weight change over time: a comparison between U.S. Hispanics and other population sub-groups.

In recent decades there has been an increasing interest in understanding the role of social and physical contexts in influencing health behaviors and outcomes. This is especially true for weight, which is considered to be highly dependent on environmental factors. The evidence linking neighborhood characteristics to weight in the United States, however, is mixed. Many studies in this area are hampered by cross sectional designs and a limited scope, insofar as they investigate only one dimension of neighborhood context. It is also unclear to what extent neighborhood characteristics account for racial/ethnic disparities in weight. Using longitudinal data from the Los Angeles Family and Neighborhood Survey (L.A. FANS), we compare patterns of weight change between Hispanics and other racial and ethnic groups in order to evaluate whether we observe a pattern of unhealthy assimilation in weight among Hispanic immigrants and to identify differences in the rate at which different groups gain weight over time. We also explore the extent to which patterns of weight change are related to a wider range of community characteristics. We find that weight increases across all groups between the two study waves of L.A. FANS and that the increases are significant except for Asians/Pacific Islanders. With respect to differences in the pace of weight change, second and higher generation Hispanic women and black men gain weight more rapidly than their first generation Hispanic counterparts. Although the evidence presented indicates that first generation Hispanics gain weight, we do not find evidence for convergence in weight since the U.S.-born gain weight at a more rapid rate. The inclusion of community-level variables does not alter the relationships between the race, ethnicity, and immigrant generation categories and weight change. Of the six types of community characteristics considered, only collective efficacy is consistently and significantly associated with weight change, although the protective effect of neighborhood collective efficacy is seen only among women.

The health impacts of international migration on Mexican women.

Mexican migration to the USA is a phenomenon that affects a significant number of Mexican households. In the area of health, considerable research has been devoted to international migrants, but less is known about the health impacts of migration on other household members, particularly the wives of migrants. I used data from the Mexican Migration Project to investigate the health impacts of having a migrant husband. As part of my analysis I explored the relationship between the husbands' migration and several health conditions and behaviours among the wives. In contrast to existing research on the subject, I also considered whether the amount of time the husband spent in the US mediates the relationship between migration and health. Finally, I addressed the possibility that the wives of migrants differ in their initial health endowments from the wives of non-migrants. I found that despite having similar initial health endowments, the wives of migrants have poorer mental health, a higher prevalence of heart disease, and they are more likely to be obese or overweight than the wives of non-migrants.

PP117. Measurement of sFlt-1 and PlGF for prediction of pregnancy associated diseases.

INTRODUCTION: Severe preeclampsia is associated with characteristic changes of sFlt-1 and PlGF levels in the maternal serum. OBJECTIVES: The aim of our study is the determination of the predictive value of sFlt-1 and PlGF for preeclampsia and other pregnancy associated diseases in women with a pathological uterine Doppler measurement during the second trimester of pregnancy. METHODS: An updated analysis of an ongoing prospective trial will be presented. Criterion of inclusion was a bilateral pathological uterine Doppler measurement with an increase of the resistance index (RI) >95th percentile and/or a bilateral postsystolic notch during 19 and 24 weeks. Ratio of sFlt-1 and PlGF was repeatedly measured during pregnancy using a full-automated system (Elecsys®, Roche). RESULTS: Presently, we recruited 36 patients. Full data are available from 17 patients. Out of these in 23.5% (n=4) a delivery before 37 weeks was indicated. 41% of all newborns (7/17) showed a birth weight <5th percentile. 23.5% of all patients developed a hypertensive pregnancy disorder but without fulfilling the criterions of preeclampsia. Only two patients had a sFlt-1/PlGF ratio >95th percentile. In both cases we found severe fetal growth retardation. One of them developed a pregnancy related hypertension based on an antiphospholipid syndrome. CONCLUSION: The additional measurement of the sFlt-1/PlGF ratio in a high risk group of pregnancies may improve the prediction of severe pregnancy related diseases during the second trimester. But keeping the low incidence of severe preeclampsia in mind, the measurements seem to be only usefulness in a high risk population. Although we reported presently only of a small part of our study population the sFlt-1/PlGF ratio did not revealed a good specificity for prediction of preeclampsia. Pathological values were also found in cases with fetal growth retardation without signs of preeclampsia.

Healthier before they migrate, less healthy when they return? The health of returned migrants in Mexico.

Over the course of the 20th century, Mexico-U.S. migration has emerged as an important facet of both countries, with far reaching economic and social impacts. The health of Mexican immigrants in the U.S. has been well studied, but relatively less is known about the health of returned migrants to Mexico. The objectives of this paper are twofold. Relying on health data pertaining to two stages of the life course, early life health (pre-migration) and adult health (post-migration) from the Mexican Migration Project gathered between 2007 and 2009, we aim to assess disparities in adult health status between male returned migrants and male non-migrants in Mexico, accounting for their potentially different early life health profiles. While we find evidence that returned migrants had more favorable early life health, the results for adult health are more complex. Returned migrants have a higher prevalence of heart disease, emotional/psychiatric disorders, obesity, and smoking than non-migrants but no differences are found in self-rated health, diabetes, or hypertension.

Socioeconomic differences in obesity among Mexican adolescents.

OBJECTIVE: We investigate socioeconomic disparities in adolescent obesity in Mexico. Three questions are addressed. First, what is the social patterning of obesity among Mexican adolescents? Second, what are the separate and joint associations of maternal and paternal education with adolescent obesity net of household wealth? Third, are there differences in socioeconomic status (SES) gradients among Mexican boys and girls, rural residents and non-rural residents? METHODS: Using data from the Mexican National Health Survey 2000 we examined the slope and direction of the association between SES and adolescent obesity. We also estimated models for sub-populations to examine differences in the social gradients in obesity by sex and non-rural residence. RESULTS: We find that household economic status (asset ownership and housing quality) is positively associated with adolescent obesity. High paternal education is related to lower obesity risk, whereas the association between maternal education and obesity is positive, but not always significant. CONCLUSION: The household wealth components of SES appear to predispose Mexican adolescents to higher obesity risk. The effects of parental education are more complex. These findings have important policy implications in Mexico and the United States.