Relative adrenal insufficiency in the critical care setting: debunking the classic myth.

BACKGROUND: Classic teaching states that chronic adrenal insufficiency is associated with hyponatremia, hyperkalemia, hypercalcemia, hypoglycemia, and eosinophilia. We hypothesize that these diagnostic markers do not predict relative adrenal insufficiency (RAI) in the critically ill or injured patient. METHODS: Chart review of surgical, trauma, and medical patients admitted over 7 years to a critical care unit was performed to evaluate cortisol levels drawn for suspicion of RAI, which was defined as a cortisol concentration <25 mcg/dl. Laboratory parameters were defined as hyponatremia <135 mmol/l, hyperkalemia >5.3 mmol/l, hypercalcemia >2.55 mmol/l (10.2 mg/dl), hypoglycemia <3.89 mmol/l (70 mg/dl), and eosinophilia >5%. RESULTS: A total of 212 patients had cortisol levels drawn. Fifty-seven percent were male and their mean age was 59 years. Fifty-three percent had RAI. Average cortisol level was 30.5 µg/dl. No significant differences were seen in mean potassium, sodium, calcium, or glucose levels between RAI and non-RAI patients. Few patients had laboratory values consistent with RAI. In fact, many with RAI had opposite findings: 75% had hypernatremia, 90% had hypokalemia, 100% had hypocalcemia, and 97% had hyperglycemia. Eosinophilia was statistically significant (P = 0.026). CONCLUSION: Hyponatremia, hyperkalemia, hypercalcemia, and hypoglycemia do not predominate in RAI and laboratory values are of minimal value in predicting patients with RAI.

Two-Parameter Quasi-Ballistic Transport Model for Nanoscale Transistors.

We show that by adding only two fitting parameters to a purely ballistic transport model, we can accurately characterize the current-voltage characteristics of nanoscale MOSFETs. The model is an extension of Natori's model and includes transmission probability and drain-channel coupling parameter. The latter parameter gives rise to a theoretical RON that is significantly larger than those predicted previously. To validate our model, we fabricated n-channel MOSFETs with varying channel lengths. We show the length dependence of these parameters to support a quasi-ballistic description of our devices.

Chronic thromboembolic pulmonary hypertension as an uncommon presentation of primary antiphospholipid syndrome.

Antiphospholipid syndrome is an autoimmune disease characterized pathophysiologically by the presence of antiphospholipid antibodies and > or =1 clinical manifestation, the most common being venous or arterial thrombosis. We describe the case of a 40-year-old male with unexplained severe pulmonary arterial hypertension with a seven-day history of progressive shortness of breath, hemoptysis, chest discomfort and bilateral pedal edema. Electrocardiographic, echocardiographic and imaging studies showed changes consistent with chronic thromboembolic pulmonary hypertension. Further work-up showed positive anticardiolipin antibodies and lupus anticoagulant with negative features for lupus with negative primary thrombophilic studies as well. The patient was managed adequately with oral anticoagulation with improvement of his clinical status and referred to a tertiary care center to be screened for pulmonary thromboendarterectomy. For patients meeting surgical selection criteria, pulmonary thromboendarterectomy has demonstrated positive outcomes with respect to survival, functionality and quality of life. We discuss the pathophysiology and treatment as well as novel therapies in nonsurgical candidates with chronic thromboembolic pulmonary hypertension in the setting of primary antiphospholipid syndrome.

Adequacy of outpatient care among hospitalized adult asthmatics in a southwest US border city.

Over 3 years we studied the baseline degree of asthma severity and the adequacy of the usual medical management among asthmatics admitted to a large US-Mexican border county hospital. The study design consisted of 2 years of retrospective chart review and 1 year of prospective semistructured interview collection. Patients were at least 18 years of age and required acute care and hospital admission for asthma exacerbations. The 127 patients studied accounted for 166 hospital admissions for asthma related primary diagnoses. Most were Hispanic and medically indigent, and only 39% of patients whose asthma severity indicated the use of inhaled corticosteroid medications reported taking them. Most of the hospitalized asthmatic patients studied were on inadequate outpatient medical regimens for the baseline severity of their asthma. Underuse of inhaled corticosteroids was the predominant medication deficiency. Other shortcomings identified in their routine management included a lack of pulmonary function testing, basic asthma education, and treatment by a practitioner qualified in the care of chronic asthma.

Impacts of land-use and land-cover change on stream hydrochemistry in the Cerrado and Amazon biomes.

Studies on the impacts of land-use and land-cover change on stream hydrochemistry in active deforestation zones of the Amazon agricultural frontier are limited and have often used low-temporal-resolution datasets. Moreover, these impacts are not concurrently assessed in well-established agricultural areas and new deforestations hotspots. We aimed to identify these impacts using an experimental setup to collect high-temporal-resolution hydrological and hydrochemical data in two pairs of low-order streams in catchments under contrasting land use and land cover (native vegetation vs. pasture) in the Amazon and Cerrado biomes. Our results indicate that the conversion of natural landscapes to pastures increases carbon and nutrient fluxes via streamflow in both biomes. These changes were the greatest in total inorganic carbon in the Amazon and in potassium in the Cerrado, representing a 5.0- and 5.5-fold increase in the fluxes of each biome, respectively. We found that stormflow, which is often neglected in studies on stream hydrochemistry in the tropics, plays a substantial role in the carbon and nutrient fluxes, especially in the Amazon biome, as its contributions to hydrochemical fluxes are mostly greater than the volumetric contribution to the total streamflow. These findings demonstrate that assessments of the impacts of deforestation in the Amazon and Cerrado biomes should also take into account rapid hydrological pathways; however, this can only be achieved through collection of high-temporal-resolution data.

Providers of herbal products in the largest US-Mexico border community.

We surveyed providers of herbal products in El Paso, Texas, and Ciudad Juárez, México, to find out which herbal products they used, the content and place of origin of the products, and the illnesses for which the products were recommended. Providers were selected randomly from Ciudad Juárez and El Paso. Most of the herbal products sold in El Paso (98%) are from the United States, whereas most sold in Ciudad Juárez (89.6%) are from México. People in El Paso tend to consume herbal or natural supplements for weight loss or muscle enhancement; those in Ciudad Juárez use herbal products (mostly crude plants) to treat specific illnesses. Ciudad Juárez and El Paso are bordering cities; however, the herbal products consumed by their respective populations are distinct, both in content and method of use.

Landscape cultivation alters δ³°Si signature in terrestrial ecosystems.

Despite increasing recognition of the relevance of biological cycling for Si cycling in ecosystems and for Si export from soils to fluvial systems, effects of human cultivation on the Si cycle are still relatively understudied. Here we examined stable Si isotope (δ(30)Si) signatures in soil water samples across a temperate land use gradient. We show that - independent of geological and climatological variation - there is a depletion in light isotopes in soil water of intensive croplands and managed grasslands relative to native forests. Furthermore, our data suggest a divergence in δ(30)Si signatures along the land use change gradient, highlighting the imprint of vegetation cover, human cultivation and intensity of disturbance on δ(30)Si patterns, on top of more conventionally acknowledged drivers (i.e. mineralogy and climate).

Bi-national evaluation of herbal product use on the United States/México border.

The study objective was to compare the prevalence of herbal product use between El Paso, Texas, and Ciudad Juárez, Chihuahua, the largest U.S./México border population. 500 households on each side of the border were randomly selected following a strict procedure for household and participant selection. 1001 adult residents of selected households participated. Trained bi-lingual interviewers conducted semistructured interviews using a bi-lingual questionnaire. A chi-square test was used to compare populations when considering discrete variables and a t test was used for continuous variables. There was no significant difference in the overall prevalence of herbal product (HP) use between the El Paso (68%) and Ciudad Juárez samples (65%). El Paso residents used a greater number of HPs compared to Ciudad Juárez residents (P = 0.001). The most common HPs used in El Paso were chamomile, aloe vera, garlic, peppermint and lime. In Ciudad Juárez, they were chamomile, eucalyptus, garlic, linden tree flower and peppermint. In addition, intra-city variation in the use of HPs was observed. On both sides of the border, relatives were the most common source of advice regarding HP use, and most HPs were reportedly used in raw form. While participants in both groups believed that the HPs were effective and safe, a large number of HPs that could potentially be responsible for drug interactions, and side effects were identified. Very low disclosure rates to physicians were reported (33% in El Paso and 14% in Ciudad Juárez). A high prevalence of HP use was documented on both sides of the U.S./México border. Some significant variations in HP use were also identified. The possibilities of HP-related problems combined with low disclosure rates are of significant concern.

A clinical pilot study of the dimensional accuracy of double-arch and complete-arch impressions.

STATEMENT OF PROBLEM: It has been suggested that articulated casts fabricated with the double-arch impression technique may have superior occlusal accuracy than those fabricated with a single complete-arch impression. However, lack of tray rigidity may lead to flexure of the impression/tray complex, resulting in inaccurate dies in the bucco-lingual dimension. PURPOSE: This clinical pilot study compared the dimensions of dies fabricated with 3 types of double-arch impressions to dies fabricated with the conventional complete-arch, custom tray method. MATERIAL AND METHODS: Thirty-five addition silicone impressions were made of cast metal copings cemented onto natural teeth prepared as complete-crown abutments. Four combinations of tray types and impression material viscosity were used: (1) complete-arch, custom acrylic trays loaded with heavy-bodied material; (2) double-arch, disposable plastic trays loaded with heavy-bodied material; (3) double-arch, disposable plastic trays loaded with putty material; and (4) double-arch, reusable brass metal trays loaded with heavy-bodied material. Immediately prior to tray insertion, light-bodied impression material was syringed over all copings as a wash. The 4 copings were fabricated from cast gold and simulated metal-ceramic complete-crown thimbles with polished collars and had "projections" on the occlusal surfaces. The impressions were poured in type IV die-stone. Bucco-lingual and inter-abutment dimensions were measured. The differences between the stone dimensions and cast metal control dimensions were calculated and converted to percent dimensional change. The data were analyzed with 1-way analysis of variance, Student t tests, and Mann-Whitney tests (P<.05). RESULTS: The plastic double-arch tray loaded with heavy-viscosity addition silicone and a low-viscosity wash produced the least accurate combination inter- and intra-abutment dimensions. For this protocol, 1.17% mean dimensional change was recorded. This result was significantly different than that obtained for the other 3 impression methods tested. No significant differences were found between the complete-arch method and protocols in which putty was loaded in a plastic or metal tray. CONCLUSION: Within the limitations of this pilot study, the more rigid tray/impression material combinations more accurately replicated stone dies.

Herbals and asthma: usage patterns among a border population.

BACKGROUND: The use of herbal products (HP) is rising in the US. Higher rates of HP use have been documented in the US/Mexico border population, as well as increasing concerns about herbal-related adverse events. OBJECTIVE: To evaluate the prevalence of HP use in adult asthmatic patients requiring hospitalization and the frequency of HP documentation in medical records. METHODS: We conducted a retrospective chart review of admissions for asthma to determine the frequency of HP documentation. Additionally, during a 12-month period, a bilingual interviewer conducted prospective, semistructured interviews with patients with asthma exacerbations to record data on HPs used specifically for the treatment of asthma. RESULTS: A total of 67 cases were chart-reviewed retrospectively; 60 patients were interviewed prospectively. We found no documentation of HP use by chart review, while prospective interviews showed that 42% of patients reported using HPs for the treatment of asthma. The most common HPs used were oregano 28%, chamomile 20%, garlic 16%, eucalyptus 12%, and lime 12%. Ten patients reported taking an HP that could potentially exacerbate their asthma and 18 patients reported using an HP that could interact with other medications or cause other types of adverse events. CONCLUSIONS: An obvious lack of documentation for HP use was observed in the medical records reviewed. Because a number of HPs that are commonly used by residents along the border can interact with antiasthmatic agents and/or result in compromised asthma control, questions about HP use should be included in routine history taking.