Novel insights on new particle formation derived from a pan-european observing system.

The formation of new atmospheric particles involves an initial step forming stable clusters less than a nanometre in size (<~1 nm), followed by growth into quasi-stable aerosol particles a few nanometres (~1-10 nm) and larger (>~10 nm). Although at times, the same species can be responsible for both processes, it is thought that more generally each step comprises differing chemical contributors. Here, we present a novel analysis of measurements from a unique multi-station ground-based observing system which reveals new insights into continental-scale patterns associated with new particle formation. Statistical cluster analysis of this unique 2-year multi-station dataset comprising size distribution and chemical composition reveals that across Europe, there are different major seasonal trends depending on geographical location, concomitant with diversity in nucleating species while it seems that the growth phase is dominated by organic aerosol formation. The diversity and seasonality of these events requires an advanced observing system to elucidate the key processes and species driving particle formation, along with detecting continental scale changes in aerosol formation into the future.

Human T-lymphotropic virus type III infection in previously immunocompromised hosts.

The human T-lymphotropic virus type III (HTLV-III) is the primary etiologic agent of the acquired immunodeficiency syndrome (AIDS). HTLV-III infection in patients with prior underlying immune deficiency states such as cancer has not yet been studied. We report on the occurrence of clinically atypical opportunistic infections in previously immunocompromised patients that resulted from transfusion-acquired HTLV-III infection. Development of unusual infectious diseases in patients with neoplasms and other underlying immune deficiency disorders should lead to consideration of HTLV-III infection. Surveillance data should be obtained on these patients to accurately define the scope of HTLV-III infection.

Physical and chemical processes of air masses in the Aegean Sea during Etesians: Aegean-GAME airborne campaign.

High-resolution measurements of gas and aerosols' chemical composition along with meteorological and turbulence parameters were performed over the Aegean Sea (AS) during an Etesian outbreak in the framework of the Aegean-GAME airborne campaign. This study focuses on two distinct Etesian patterns, with similarities inside the Marine Atmospheric Boundary Layer (MABL) and differences at higher levels. Under long-range transport and subsidence the pollution load is enhanced (by 17% for CO, 11% for O3, 28% for sulfate, 62% for organic mass, 47% for elemental carbon), compared to the pattern with a weaker synoptic system. Sea surface temperature (SST) was a critical parameter for the MABL structure, turbulent fluxes and pollutants' distribution at lower levels. The MABL height was below 500 m asl over the eastern AS (favoring higher accumulation), and deeper over the western AS. The most abundant components of total PM1 were sulfate (40-50%) and organics (30-45%). Higher average concentrations measured over the eastern AS (131 ± 76 ppbv for CO, 62.5 ± 4.1 ppbv for O3, 5.0 ± 1.1 µg m(-3) for sulfate, 4.7 ± 0.9 µg m(-3) for organic mass and 0.5 ± 0.2 µg m(-3) for elemental carbon). Under the weaker synoptic system, cleaner but more acidic air masses prevailed over the eastern part, while distinct aerosol layers of different signature were observed over the western part. The Aitken and accumulation modes contributed equally during the long-range transport, while the Aitken modes dominated during local or medium range transport.

Antimicrobial combinations in the therapy of infections due to gram-negative bacilli.

Antimicrobial combinations are used most frequently to provide broad-spectrum coverage; however, they are also frequently employed to enhance antimicrobial activity (synergism). Although there is extensive in vitro documentation of synergism for many antibiotic combinations, a clear advantage for these combinations has been difficult to demonstrate in clinical studies. Several types of combinations have been useful in clinical medicine and frequently result in synergism. These include combinations of a cell wall-active agent with an aminoglycosidic aminocyclitol, combinations of a beta-lactamase inhibitor with a beta-lactam, and combinations of agents that inhibit sequential steps in a metabolic pathway. Given its spectrum of activity, aztreonam will often be used with clindamycin or a beta-lactam antibiotic. Combinations of beta-lactams may be synergistic via several mechanisms. However, these combinations also exhibit significant potential for antagonism when used against gram-negative bacilli and, therefore, require careful evaluation prior to clinical use.

Beta-lactam/aminoglycoside combinations: interactions and their mechanisms.

Combinations of beta-lactams with aminoglycosides are widely used in the therapy of infections. There are a number of theoretic advantages to using such combinations. Indeed, combinations of beta-lactams and aminoglycosides usually result in synergism or indifference and very rarely in antagonism. The mechanisms of synergism, resistance to synergism, and antagonism have been studied extensively in enterococci; further studies are necessary to define such mechanisms in other organisms.

Phase I study of 2'-3'-dideoxyinosine administered orally twice daily to patients with AIDS or AIDS-related complex and hematologic intolerance to zidovudine.

PURPOSE: To evaluate the safety and hematologic tolerance of 2'-3'-dideoxyinosine (didanosine, ddI) in subjects with acquired immunodeficiency syndrome (AIDS) or AIDS-related complex and prior hematologic intolerance to zidovudine. PATIENTS AND METHODS: A Phase I trial with two dose groups at a single-center, university-affiliated hospital ambulatory care center. Of 30 subjects enrolled, 21 had AIDS and nine had AIDS-related complex. All had CD4 lymphocyte counts less than 0.2 x 10(9)/L at entry. Didanosine was administered orally twice daily at a total daily dose of 750 mg or 1,500 mg for 12 weeks. Subjects who completed the 12-week study continued to receive ddI at the lower dose. All subjects were monitored for toxicity. Virologic and immunologic response markers were also measured. RESULTS: For the group as a whole, there was no significant decrease in mean hemoglobin level or leukocyte or platelet counts. The dose-limiting toxicity was peripheral neuropathy. Other significant toxicities included pancreatitis and hypocalcemia. Uric acid elevations were common but were without clinical consequence. A sustained decrease in serum p24 antigen of at least 50% was noted in 42% of subjects who were p24 antigen-positive at entry. The mean CD4 lymphocyte count showed an initial increase that was not sustained over the 12-week study. All subjects remained anergic to skin testing. CONCLUSIONS: Didanosine is well tolerated hematologically in some patients with prior significant hematologic intolerance to zidovudine. The toxicity profile for ddI differs from that of zidovudine and includes peripheral neuropathy and pancreatitis. Changes in CD4 lymphocyte number and HIV p24 antigen levels in some patients suggest antiviral activity of ddI in this population.

Aerosol pentamidine prophylaxis following Pneumocystis carinii pneumonia in AIDS patients: results of a blinded dose-comparison study using an ultrasonic nebulizer.

PURPOSE: To compare the efficacy and safety of three different doses of prophylactic aerosol pentamidine in patients with one prior episode of Pneumocystis carinii pneumonia (PCP) and the acquired immunodeficiency syndrome. PATIENTS AND METHODS: The design of the study was a double-blind, randomized, dose-comparison clinical trial conducted at 13 medical centers within the United States. In stage I of the trial, patients were randomized to receive either 5 mg, 60 mg, or 120 mg of aerosol pentamidine delivered biweekly with the Fisoneb (Fisons, Inc., Rochester, New York) ultrasonic nebulizer. After 24 weeks of therapy, patients entered stage II of the trial, where the 5-mg group was re-randomized to either the 60-mg or 120-mg group. RESULTS: One hundred seventy-five patients entered stage I of the trial and received prophylaxis for a mean of 123.6 days. Seven assigned to the 5-mg biweekly dosing schedule had a confirmed recurrence of PCP, compared with none in the 60-mg group (p = 0.007) and three in the 120-mg group (p = 0.304). During stage II of the trial, eight patients in the 60-mg group and one additional patient in the 120-mg group had recurrent PCP. After 52 weeks of observation, the likelihood of being PCP-free was 88.0% in the 60-mg group and 93% in the 120-mg group (p = 0.712). Minor adverse events related to aerosol pentamidine administration included cough, taste perversion, chest pain, bronchospasm, and dyspnea. These side effects were more common in the 60-mg and 120-mg treatment groups and resulted in withdrawal from the study by one patient. Serious events were more common after 24 weeks of therapy and included asymptomatic hypoglycemia (five), pancreatitis (two), pneumothorax (one), and extrapulmonary pneumocystosis (one). CONCLUSIONS: These results demonstrate that biweekly administration of 60 mg or 120 mg of aerosol pentamidine significantly decreases PCP recurrence when compared with a 5-mg regimen or findings in historic controls and is generally well tolerated. There is no significant difference in effect or safety between these two dosing regimens in patients followed for at least 52 weeks of therapy.

Characterization of serum neutralization response to the human immunodeficiency virus (HIV).

To determine the clinical significance of human neutralizing antibodies to the human immunodeficiency virus (HIV), we measured serum neutralization in patients with different clinical outcomes following HIV infection. Serum neutralization titers ranged from less than 1:5 to 1:100. The neutralization response after HIV infection appeared slow, with neutralization titers remaining low, at or below 1:5, at 7 months following seroconversion. Comparison of 78 HIV seropositive subjects with AIDS, AIDS-related complex, or no symptoms failed to reveal any significant differences in titer which correlated with clinical status. However, a greater proportion of AIDS patients with Kaposi's sarcoma (11/12) had neutralization titers of 1:20 or greater than did AIDS patients with opportunistic infections (2/11). Serum samples were analyzed by Western blot for their reactivity to specific viral proteins. Clinical status could not be predicted by a particular serological profile. However, sera which reacted with the HIV major envelope glycoprotein gp120 tended to have higher neutralization titers, suggesting that gp120 may be a target of anti-HIV neutralizing antibody in man.

Antibiotic combinations.

Combinations of antimicrobial agents are most often used to provide empiric broad spectrum coverage. Other potential reasons for combination therapy include treatment of polymicrobial infections, to enhance killing or inhibition (synergism), to reduce the potential for developing resistance, and less commonly to allow reduction in the dose of a toxic agent. However, combination regimens are often used unnecessarily and can result in increased side effects, costs, and other undesirable effects.

Prey preference in stoneflies: a comparative analysis of prey vulnerability.

Laboratory feeding trials were conducted with the predaceous stonefly Hesperoperla pacifica and a number of mayfly and dipteran prey species to investigate the effects of predator size, and prey size and morphology, on the predator's success. Observations under dim red light permitted estimation of encounter rate (E/min), attack propensity (A/E), capture success (C/A) and handling time (HT). For prey of a particular species and size, HT decreased log-linearly with increasing predator size. Across all prey categories, HT increased log-linearly with increasing values of the ratio prey dry wt/predator dry wt, and differences among species appeared to be small. Overall, capture success was low, but C/A was higher for dipterans than for mayflies, especially with large H. pacifica. Predator size affected C/A when prey fell within a certain size range, but was not a detectable influence with very small or very large prey. Values of A/E of near 10% typified many predatorprey combinations; however, ephemerellid mayflies suffered markedly fewer attacks, and values of A/E up to 30% were obtained with some species-size combinations. We estimated benefit to the predator first as prey wt ingested per unit time (dry wt/HT), and second by mutliplying the former term by capture success. Values increased with increasing size of the predator, and inclusion of the C/A term indicated that predators would obtain greater reward from small relative to large prey, and from dipterans relative to mayflies. Howerver, there was little evidence that attacks were biased toward more profitable prey. We compare the relative contributions of E/min, A/E and C/A to prey choice, and discuss their applicability to predation events in nature.

Street canyon aerosol pollutant transport measurements.

Current understanding of dispersion in street canyons is largely derived from relatively simple dispersion models. Such models are increasingly used in planning and regulation capacities but are based upon a limited understanding of the transport of substances within a real canyon. In recent years, some efforts have been made to numerically model localised flow in idealised canyons (e.g., J. Appl. Meteorol. 38 (1999) 1576-89) and stepped canyons (Assimakopoulos V. Numerical modelling of dispersion of atmospheric pollution in and above urban canopies. PhD thesis, Imperial College, London, 2001) but field studies in real canyons are rare. To further such an understanding, a measurement campaign has been conducted in an asymmetric street canyon with busy one-way traffic in central Manchester in northern England. The eddy correlation method was used to determine fluxes of size-segregated accumulation mode aerosol. Measurements of aerosol at a static location were made concurrently with measurements on a platform lift giving vertical profiles. Size-segregated measurements of ultrafine and coarse particle concentrations were also made simultaneously at various heights. In addition, a small mobile system was used to make measurements of turbulence at various pavement locations within the canyon. From this data, various features of turbulent transport and dispersion in the canyon will be presented. The concentration and the ventilation fluxes of vehicle-related aerosol pollutants from the canyon will be related to controlling factors. The results will also be compared with citywide ventilation data from a separate measurement campaign conducted above the urban canopy.

A biomedical and feminist perspective on women's experiences with weight management.

Weight concerns and dieting have become so normative for U.S. women that weight is the lens through which experience is viewed. The obsession with weight and dieting among women is considered by feminists to be one result of the oppression by women resulting from questionable weight standards and weight control programs that foster a view of overweight as a sign of addiction and lack of control. Feminist critique is used to deconstruct both the literature related to weight standards and health and the research on weight loss/weight management. Feminist and ethnographic methods are used to describe successful and unsuccessful experiences with weight management of 20 Euro-American women who had participated in a 1985 weight study and agreed to be reinterviewed. Success at weight management was examined from a biomedical perspective using Body Mass Index (BMI) norms and from a feminist perspective using participants' subjective definitions of success. Based upon BMI, only 8 members of the study group were defined as successful, whereas based upon the women's perspectives, 11 members were successful. Participants' definitions of successful weight management were divergent from biomedical definitions and could be categorized into three perspectives: biomedical, reframed normal weight, and holistic. Women who ascribed to the biomedical definition of success embodied the cultural ideal of thinness by adhering to an underweight weight norm. Participants using the reframed normal weight definition of success rejected biomedical weight norms and created their own weight norms. The holistic perspective on success involved the use of a broader, health-focused definition of successful weight management and offers some directions for revising current health promotion care relative to weight.

New directions for the study of overweight.

In this issue, three authors contribute to our knowledge of triggers or cues to weight-related behavior. Two of these authors focus on the effect of emotion on eating behavior. Popkess-Vawter, Wendel, Schmoll, and O'Connell (1998, in this issue) explicate reversal theory as a way to account for feelings and stress that trigger weight cyclers to overeat. Timmerman (1998, in this issue), in a study of nonpurge binge eaters, reports the relationship between caloric intake patterns and binge eating. Both researchers have added to our knowledge about triggers to eating behavior. Finally, Brink and Ferguson (1998), in their study of male and female successful dieters, add to the limited knowledge concerning triggers to weight loss. They describe reasons for deciding to lose weight among a population of successful underweight, normal weight, and obese dieters. Three authors contribute to the new weight research thrust of prevention. Two of the authors report the results of intervention studies. Reifsnider (1998, in this issue), in the only article on children, presents a follow-up study of a family-focused, community-based nursing intervention for growth-deficient, low-income Euro-American and Mexican American preschool children. Her work is an example of the context- and lifestyle-sensitive prevention-focused studies needed in weight research. Ciliska (1998, in this issue) reports findings from a randomized trial of a psycho-educational intervention with obese healthy women aimed at increasing self-esteem and decreasing restrained eating patterns. Her work follows some new thinking in the area of weight control that recognizes the dangers of chronic dieting and proposes a focus on self-acceptance, better nutrition, regular physical activity, and the prevention of further weight gain triggered by chronic dieting (Brownell & Cohen, 1995). Walker (1998, in this issue), the third author, in a multiethnic study of new mothers, explores the concept of weight-related distress and associations of anthropometric and psychosocial variables with feelings about weight. Her work adds to our understanding about critical periods and risks for weight gain. Allan (1998, in this issue), in a study of African American, Euro-American, and Mexican American women, reports women's explanatory models of overweight and the congruence of these models with professional models and recommendations for treatment for overweight. Her research contributes needed understandings of how high-risk populations view overweight, how participants' lifestyles and situations influence their ideas about weight, and how these perspectives influence efforts to control weight. Nursing needs to continue to refine and rethink what constitutes research on weight. This special issue offers some examples of scholars attempting to trailblaze new directions in nursing weight research. One thrust has been the significant attention on weight as a focus of investigation and not just as one of several health behaviors. A second and equally compelling area of inquiry has been the explicit attention directed to studying people of color, especially women, within the social context of their lives. Because ethnicity, social status, and gender are inextricably intertwined with health, one challenge is to try to understand weight issues through an ethnic, gender, and social status lens. Researchers who embrace this paradigm refuse to look at weight as a homogeneous condition but focus their attention instead on specific subgroups in the population without making middle-class Euro-Americans the norm. The number of researchers who are examining connections between ethnicity and social status and weight is growing. The complexity of weight-health promotion requires that we not only boldly examine weight in relationship to the individual in context but also explicate the macroenvironmental influences on weight. More needs to be done to translate findings from this body of research into better models

Explanatory models of overweight among African American, Euro-American, and Mexican American women.

Ethnographic interviewing methods were used to explore women's explanatory models (EMs) of overweight and the congruence of these models with professional models and professionally recommended treatments for overweight. Through community-based snowball and theoretical sampling, 40 African American, 40 Euro-American, and 40 Mexican American women of varying social status and weight participated in multiple ethnographic interviews, which were subsequently interpreted using domain analysis and constant comparison. Study participants' EMs of overweight ranged from simple to complex, were generally similar across the three study groups, and only partially congruent with professional EMs of obesity. Major differences in EMs between the study groups were found in the dimensions of etiologies and consequences of overweight. There was partial congruence between participants' EMs and professionally recommended treatments for overweight.

Knowing what to weigh: women's self-care activities related to weight.

Overweight and obesity are major health problems among women. Data were collected from intensive interviews of 37 white middle-class and working-class women to explore how women interpret and use health information in the practice of self-care related to weight management. The findings indicated that all women develop personalized norms or categories of physical identity for weight and criteria for knowing if they weigh too much or too little. These norms and criteria represent creative self-care tactics devised without professional assistance in weight management and without regard for the cultural pressure to be thin. The results of this study have relevance for theory development and nursing practice related to women's health. In addition, they support the need for more community-based studies of women to understand the cultural and physical environments in which women conduct their lives and maintain their health.

Challenging the focus on technology: a critique of the medical model in a changing health care system.

The medical model and medical technology have had a pervasive effect on society. Their importance to nursing and to nursing's clients cannot be overstated. This article explores the belief system of medicine and challenges its "germ theory" conceptual underpinnings. Other issues explored are the lack of established efficacy of practice stemming from the medical model; the attendant but unaddressed ethical and iatrogenic questions; the model's destructive effect on health and well-being; and, finally, the economic consequences of the medical model for consumers and the practice of other professional groups. Nurses are urged to consider paradigms that derive from ecological and process orientations to support nursing's concern with health and quality of life.

Weight management practices among primary care providers.

This pilot study examined how primary care providers manage patients with weight problems, an important component of primary care. A convenience sample of 17 nurse practitioners and 15 physicians were surveyed about assessments and interventions used in practice for weight management along with perceived barriers to providing effective weight management. Practice patterns between gender, profession and practice setting of the nurse practitioners were compared.