Evolution of anthropogenic aerosols in the coastal town of Salina Cruz, Mexico: part II particulate phase chemistry.

An analysis of atmospheric gases and particles during periods of land and sea breezes in a coastal city in southwest Mexico indicates limited removal of total particle mass by deposition during periods when the air resides over the ocean. The average PM(2.5) mass concentrations for land and sea breeze samples were 25+/-1.0 and 26+/-1.0 microg m(-3), respectively. The average sum of the ion concentrations (NH(4)(+), SO(4)(2-), NO(3)(-), Na(+), Cl(-)) were 10 and 11.8 microg m(-3) for the samples taken during land and sea breeze periods. The average total carbon concentrations were 6.0 and 5.3 microg m(-3) for land and sea breeze periods. The mass of sulfate in particles of ocean origin, 3.3+/-2.8 microg m(-3), is marginally higher than those originating from the land, 2.0+/-0.8 microg m(-3), presumably as a result of the conversion of SO(2) recirculated from the city. The fraction of sulfate, nitrate and ammonium ions in rainwater samples is almost a factor of two higher than the fraction measured on filtered air samples. The rainwater also contains significant concentrations of elemental and organic carbon. This study, although extending over a period of only 15 days, with limited chemical samples, suggests that recirculation of anthropogenic particles from coastal cities should be taken into consideration when diagnosing and predicting air quality in such regions.

Evolution of anthropogenic aerosols in the coastal town of Salina Cruz, Mexico: part I particle dynamics and land-sea interactions.

Measurements of aerosol particles in a coastal city in southeast Mexico show that the concentrations and optical properties are strongly linked to land and sea breezes. Maximum concentrations of condensation nuclei (CN), black carbon (BC) and particle bound polycyclic aromatic hydrocarbons (PPAH) occur during land breeze periods and decrease with the sea breeze. The concentrations of particles in air from the ocean, however, remain significantly above background, maritime values as a result of the recirculation of anthropogenic emissions. The mass size distribution is dominated by particles larger than 5 microm when wind speeds exceed 4 m s(-1); otherwise, the uptake of water vapor onto unactivated particles is the process that dominates the growth of particles. Precipitation removes particles larger than 5 microm but CN, BC and PPAH concentrations are minimally affected.

Evidence that nitric acid increases relative humidity in low-temperature cirrus clouds.

In situ measurements of the relative humidity with respect to ice (RHi) and of nitric acid (HNO3) were made in both natural and contrail cirrus clouds in the upper troposphere. At temperatures lower than 202 kelvin, RHi values show a sharp increase to average values of over 130% in both cloud types. These enhanced RHi values are attributed to the presence of a new class of HNO3-containing ice particles (Delta-ice). We propose that surface HNO3 molecules prevent the ice/vapor system from reaching equilibrium by a mechanism similar to that of freezing point depression by antifreeze proteins. Delta-ice represents a new link between global climate and natural and anthropogenic nitrogen oxide emissions. Including Delta-ice in climate models will alter simulated cirrus properties and the distribution of upper tropospheric water vapor.

The detection of large HNO3-containing particles in the winter Arctic stratosphere.

Large particles containing nitric acid (HNO3) were observed in the 1999/2000 Arctic winter stratosphere. These in situ observations were made over a large altitude range (16 to 21 kilometers) and horizontal extent (1800 kilometers) on several airborne sampling flights during a period of several weeks. With diameters of 10 to 20 micrometers, these sedimenting particles have significant potential to denitrify the lower stratosphere. A microphysical model of nitric acid trihydrate particles is able to simulate the growth and sedimentation of these large sizes in the lower stratosphere, but the nucleation process is not yet known. Accurate modeling of the formation of these large particles is essential for understanding Arctic denitrification and predicting future Arctic ozone abundances.

Blastomycosis: more evidence for exposure near one's domicile.

BACKGROUND: Our previous publications on the epidemiology of blastomycosis suggested that the etiologic organism, Blastomyces dermatitidis, may be acquired at home, however this view was challenged in an editorial. METHODS: 1) Field study of 2 properties that preliminarily suggested disease acquisition in the home. Owner interviews, site visits and environmental cultures using our in-vitro technique were used. 2) An address registry of human and dog blastomycosis cases was constructed from extensions of our previously published case series. 3) Literature review. RESULTS: 1) Blastomycosis occurred in a dog (December, 1998) and then a cat confined to its home (September, 1999), from a household in urban Manitowoc County, WI; and additionally in a house-confined cat (July, 1998) at a home in Milwaukee, WI. Interviews implicated the basement and the attic or basement, respectively, as the most likely source of infection at these homes. Environmental cultures were negative for Blastomyces. Of the 229 domiciles in the registry, a minimum of 27 (12%) were associated with more than one blastomycosis case, 10 sites with more than two and 7 with more than three. In 4 domiciles, repeat cases occurred in different families. Most cases were separated by 1 year or more (range: 3 weeks to 7 years). Recent case series reveal a minority of outdoor activities and occupations among humans with blastomycosis. The organism has been isolated from an inhabited yard and from a house being razed. CONCLUSIONS: There appears to be growing evidence that blastomycosis may be acquired at home, and that B. dermatitidis may be relatively persistent on certain properties.

Studies on the molecular ecology of Blastomyces dermatitidis.

The microecology of Blastomyces dermatitidis, the dimorphic etiologic agent of the potentially fatal systemic fungal infection, blastomycosis, is not well defined. Blastomyces dermatitidis may occur periodically at natural sites, perhaps aided by rotting organic material, animal droppings and physical changes. Semi-quantitative growth studies of B. dermatitidis on 2% agar plates determined the ability to utilize or tolerate a variety of substrates including simple and complex molecules as carbon source, and organic and inorganic nitrogen sources. Allantoin, creatinine, quanidoacetic acid, guanidine and cysteine may be used as sole nitrogen source. Allantoin in combination with dextrose, glycerol, lichenen, celloboise and other wood by-products support growth of B. dermatitidis at room temperature. The nutritional conversion of the fungus to the yeast form at room temperature, well demonstrated on allantoin/glycerol/yeast extract media, appears to be affected by certain inorganic compounds. The organism tolerates low to moderate levels of alpha-pinene, tannic acid, shikimic acid, veratryl alcohol, vanillic acid, and polyethyleneglycol-200. There are significant differences among isolates regarding growth on various substances at 20 degrees and 37 degrees centigrade. It appears that a variety of wood by-products and animal waste substrates, in combination, support the growth of B. dermatitidis. Their role in the ecological niche of B. dermatitidis, and the importance of nutritional dimorphism in the natural environment warrants further investigation.

Normocytic anemia.

Anemia is a common problem that is often discovered on routine laboratory tests. Its prevalence increases with age, reaching 44 percent in men older than 85 years. Normocytic anemia is the most frequently encountered type of anemia. Anemia of chronic disease, the most common normocytic anemia, is found in 6 percent of adult patients hospitalized by family physicians. The goals of evaluation and management are to make an accurate and efficient diagnosis, avoid unnecessary testing, correct underlying treatable causes and ameliorate symptoms when necessary. The evaluation begins with a thorough history and a careful physical examination. Basic diagnostic studies include the red blood cell distribution width, corrected reticulocyte index and peripheral blood smear; further testing is guided by the results of these studies. Treatment should be directed at correcting the underlying cause of the anemia. A recent advance in treatment is the use of recombinant human erythropoietin.

Clues to the presence of pathogenic fungi in certain environments.

The presence of various pathogenic fungi in rather unsuspected hosts and environments has always attracted the attention of the scientific community. Reports on the putative role of animals in fungal infections of humans bear important consequences on public health as well as on the understanding of fungal ecology. Fungi are ubiquitous in nature and their great capacity for adaptation allows them to survive and indeed, to thrive, in plants, trees and other natural substrata. Nonetheless, we are just beginning to learn the significance that these diverse fungal habitats have on the increasing number of immunosuppressed individuals. The accidental or permanent presence of fungi in animals, plants, soils and watercourses should not be taken too lightly because they constitute the source where potential pathogens will be contracted. If those fungal habitats that carry the largest risks of exposure could be defined, if seasonal variations in the production of infectious propagules could be determined, and if their mode of transmission were to be assessed, it would be possible to develop protective measures in order to avoid human infection. Additionally, unsuspected avenues for the exploration of fungal survival strategies would be opened, thus enhancing our capacity to react properly to their advancing limits. This paper explores several ecological connections between human pathogenic fungi and certain animals, trees, waterways and degraded organic materials. The occurrence of such connections in highly endemic areas will hopefully furnish more precise clues to fungal habitats and allow the design of control programs aimed at avoiding human infection.

The in vitro isolation of Blastomyces dermatitidis from a woodpile in north central Wisconsin, USA.

Environmental isolations of the dimorphic fungus, Blastomyces dermatitidis, the aetiologic agent of blastomycosis are rare, and have usually involved animal inoculation techniques. We report the in vitro isolation of B. dermatitidis from a woodpile in November 1997, from a private property in a highly endemic area of north central Wisconsin, USA. The woodpile was 73 m from the Wisconsin River and 5 m from a kennel which had housed nine dogs over the past 14 years, four of which had been diagnosed with blastomycosis. One of 19 samples from the property yielded B. dermatitidis after 37 degrees C incubation in a neutral aqueous solution of allantoin, Tween-80, potassium phosphate, magnesium sulphate, penicillin and streptomycin followed by plating on yeast-extract phosphate agar at 20 degrees C. Refinements of this technique may help further elucidate the ecological niche of B. dermatitidis.

Quality-of-life in technology-dependent children receiving home care, and their families--a qualitative study.

PURPOSE: This qualitative study explored quality-of-life (QL) issues among Wisconsin's technology-dependent children and their families. METHODS: Five semi-structured focus groups were held with parents, siblings and health care workers of home-dwelling children dependent upon technology such as tracheostomy, ventilator support and gastrostomy tube feedings. Focus group transcripts were analyzed using an editing style format, with each author as an independent analyst. RESULTS: QL for the child was seen as a relative term, defined within the family, dependent upon the availability of services; and expressed in terms of physical comfort and function, and integration of the child into the family and community. Positive QL aspects for families include: growth as individuals, intrinsic rewards from the child and appreciation of others with handicaps. Negative impacts on family QL include: physical and mental anguish (e.g., exhaustion, suicidal ideation, back injuries), inhibitions of normal family functions, and isolation. Home nursing was highly valued despite lack of privacy. A number of ethical issues emerged including ineffective communication and lack of QL discussions during the child's acute treatment, end-of-life decisions, and potential cuts in Medicaid services. The latter issue prompted fear of poverty and divorce among siblings. CONCLUSIONS: Technology appears to exceed the sociological and ethical components of the care of these children, and QL is defined in terms of physical comfort, functional status, adequate services, and family/community integration. Parents assume an ambiguous medical role with their child, and need respite care and advocacy from their health care team.

Epidemiology of human blastomycosis in Vilas County, Wisconsin. II: 1991-1996.

PURPOSE: A previous report identified Vilas County, Wisconsin, as an area highly endemic for blastomycosis based on a case series 1979-90. This study was done to compare the epidemiologic features of persons with this disease over the following six years. METHODS: Compilation of data from the 47 mandatory physician/laboratory case reports of blastomycosis, disease onset 1991-96, received at the Vilas County Health Department; case mapping by site visit; and statistical comparison to the previous series. RESULTS: The estimated mean annual incidence rate for Vilas County during 1991-96, 40/100,000, remains unchanged from 1984-90. Cases were again disproportionately represented in the southeast corner of the county, and 36/46 lived within 1/4 mile of water. There was a trend toward a higher proportion of female cases in this study (27/47) compared to the prior report (28/73; P = 0.06); the mean age, 47 years, did not differ. Among 32 patients whose activities were recorded, a minority engaged in hunting (4), fishing (4) and gardening (12) prior to disease onset; but 19/32 recalled excavation prior to exposure compared to 17/60 in 1979-90 (P < 0.01). Among cases with a pulmonary presentation, winter onset cases (3/40) were significantly fewer than in 1979-90 (19/55). However, over the entire 18 years there was no disproportionately represented season. CONCLUSIONS: In highly endemic Vilas County, the mean annual incidence of human blastomycosis appears stable over the past 13 years. A combined case series of 18 years reveals no predilection by gender or season of onset.

Establishing proficiency in flexible sigmoidoscopy in a family practice residency program.

BACKGROUND AND OBJECTIVES: Fiberoptic flexible sigmoidoscopy (FFS) is widely used by family physicians to evaluate abdominal problems and screen for colorectal cancer. We evaluated data on exams performed by family practice residents to determine the number of supervised procedures needed for technical proficiency at FFS. METHODS: We reviewed data recorded from all FFS procedures done at a family practice residency from October 1986-July 1994. RESULTS: A total of 262 exams were performed by 55 residents at the Family Practice Center. There was modest correlation between increasing numbers of exams and increased unassisted depth of insertion (UDI). Maximum UDI was achieved after 10-15 supervised exams. Factors such as patient gender, prior surgery, and preparation quality were also significantly correlated with UDI. Significant differences in training experience and patient selection were seen between male and female residents. CONCLUSIONS: Maximal UDI is reached after 10-15 procedures. Differences in training experiences and successful UDI based on resident gender should be studied further.

Identification of Blastomyces dermatitidis in the stool of a dog with acute pulmonary blastomycosis.

We report the identification of Blastomyces dermatitidis by microscopic examination of a direct faecal smear from a dog with pulmonary blastomycosis. A simultaneously obtained faecal culture grew Blastomyces dermatitidis. The fungus was also cultured from a transtracheal sample from this same dog. This report suggests that yeast-phase cells of B. dermatitidis may be recovered in the stool of dogs with pulmonary blastomycosis following transit through the gastrointestinal tract of swallowed infected sputum. Implications regarding the ecology of Blastomyces dermatitidis are discussed.

Candida parapsilosis infection in a rose thorn wound.

Candida parapsilosis should be recognized by primary care physicians as an important nosocomial pathogen, which is also frequently associated with sporadic skin and appendage infections. Its association with environmentally acquired skin ulcers can mimic fixed cutaneous sporotrichosis.

The epidemiology of blastomycosis in dogs: north central Wisconsin, USA.

The epidemiological features of 59 consecutive cases of blastomycosis in domestic dogs, from a single veterinary practice in Eagle River, Wisconsin over a 3-year period, were examined by owner interview. The control sample included: (i) all porcupine quill-injured dogs during this time period (outdoor exposed dogs); and (ii) every sixth dog receiving a rabies vaccination during the second year of study (representative of all dogs in the practice). The estimated mean annual incidence of blastomycosis in dogs in this region was 1420:100,000. Blastomycosis cases were more likely to reside within 400 m of a waterway (95%) than quill-injured dogs (63%, P < 0.001) or vaccinated dogs (74%, P = 0.001). Exposure to an excavation was significantly more likely among blastomycosis cases compared to quill-injured dogs, however, no differences were found for age, sex, hunting, swimming and reported exposure to beavers. The geographical clustering of cases in dogs is similar to that previously reported for humans in this region. A close proximity to waterways and an exposure to excavation are significant risk factors for blastomycosis.