A Critical Review of State-of-the-Art and Emerging Approaches to Identify Fracking-Derived Gases and Associated Contaminants in Aquifers.

High-volume, hydraulic fracturing (HVHF) is widely applied for natural gas and oil production from shales, coals, or tight sandstone formations in the United States, Canada, and Australia, and is being widely considered by other countries with similar unconventional energy resources. Secure retention of fluids (natural gas, saline formation waters, oil, HVHF fluids) during and after well stimulation is important to prevent unintended environmental contamination, and release of greenhouse gases to the atmosphere. Here, we critically review state-of-the-art techniques and promising new approaches for identifying oil and gas production from unconventional reservoirs to resolve whether they are the source of fugitive methane and associated contaminants into shallow aquifers. We highlight future research needs and propose a phased program, from generic baseline to highly specific analyses, to inform HVHF and unconventional oil and gas production and impact assessment studies. These approaches may also be applied to broader subsurface exploration and development issues (e.g., groundwater resources), or new frontiers of low-carbon energy alternatives (e.g., subsurface H2 storage, nuclear waste isolation, geologic CO2 sequestration).

Ontogeny and localization of TGF-beta type I receptor expression during lung development.

Transforming growth factor (TGF)-beta is a family of multifunctional cytokines controlling cell growth, differentiation, and extracellular matrix deposition in the lung. The biological effects of TGF-beta are mediated by type I (TbetaR-I) and II (TbetaR-II) receptors. Our previous studies show that the expression of TbetaR-II is highly regulated in a spatial and temporal fashion during lung development. In the present studies, we investigated the temporal-spatial pattern and cellular expression of TbetaR-I during lung development. The expression level of TbetaR-I mRNA in rat lung at different embryonic and postnatal stages was analyzed by Northern blotting. TbetaR-I mRNA was expressed in fetal rat lungs in early development and then decreased as development proceeded. The localization of TbetaR-I in fetal and postnatal rat lung tissues was investigated by using in situ hybridization performed with an antisense RNA probe. TbetaR-I mRNA was present in the mesenchyme and epithelium of gestational day 14 rat lungs. An intense TbetaR-I signal was observed in the epithelial lining of the developing bronchi. In gestational day 16 lungs, the expression of TbetaR-I mRNA was increased in the mesenchymal tissue. The epithelium in both the distal and proximal bronchioles showed a similar level of TbetaR-I expression. In postnatal lungs, TbetaR-I mRNA was detected in parenchymal tissues and blood vessels. We further studied the expression of TbetaR-I in cultured rat lung cells. TbetaR-I was expressed by cultured rat lung fibroblasts, microvascular endothelial cells, and alveolar epithelial cells. These studies demonstrate a differential regulation and localization of TbetaR-I that is different from that of TbetaR-II during lung development. TbetaR-I, TbetaR-II, and TGF-beta isoforms exhibit distinct but overlapping patterns of expression during lung development. This implies a distinct role for TbetaR-I in mediating TGF-beta signal transduction during lung development.

Surfactant-associated protein A inhibits LPS-induced cytokine and nitric oxide production in vivo.

The role of surfactant-associated protein (SP) A in the mediation of pulmonary responses to bacterial lipopolysaccharide (LPS) was assessed in vivo with SP-A gene-targeted [SP-deficient; SP-A(-/-)] and wild-type [SP-A(+/+)] mice. Concentrations of tumor necrosis factor (TNF)-alpha, macrophage inflammatory protein-2, and nitric oxide were determined in recovered bronchoalveolar lavage fluid after intratracheal administration of LPS. SP-A(-/-) mice produced significantly more TNF-alpha and nitric oxide than SP-A(+/+) mice after LPS treatment. Intratracheal administration of human SP-A (1 mg/kg) to SP-A(-/-) mice restored regulation of TNF-alpha, macrophage inflammatory protein-2, and nitric oxide production to that of SP-A(+/+) mice. Other markers of lung injury including bronchoalveolar fluid protein, phospholipid content, and neutrophil numbers were not influenced by SP-A. Data from experiments designed to test possible mechanisms of SP-A-mediated suppression suggest that neither binding of LPS by SP-A nor enhanced LPS clearance are the primary means of inhibition. Our data and others suggest that SP-A acts directly on immune cells to suppress LPS-induced inflammation. These results demonstrate that endogenous or exogenous SP-A inhibits pulmonary LPS-induced cytokine and nitric oxide production in vivo.

Differential expression of platelet-derived growth factor-alpha receptor by Thy-1(-) and Thy-1(+) lung fibroblasts.

Fibroblasts are heterogeneous with respect to surface markers, morphology, and participation in fibrotic responses. This study was undertaken to determine whether Thy-1(-) and Thy-1(+) rat lung fibroblasts, which have distinct and relevant phenotypes, differ in their proliferative responses to platelet-derived growth factor (PDGF) isoforms. Homogeneous populations of Thy-1(-) and Thy-1(+) fibroblasts were found to proliferate equally in the presence of PDGF-BB, but PDGF-AA-mediated proliferation occurred only in Thy-1(-) cells. This differential activity correlated with significantly higher expression of PDGF-alpha receptor in Thy-1(-) fibroblasts as shown by immunoblotting, immunofluorescence, and Northern blotting. There was a rapid increase in c-myc mRNA in Thy-1(-) but not in Thy-1(+) fibroblasts on stimulation with PDGF-AA and PDGF-BB. The PDGF-alpha receptor, which mediates signaling by all PDGF isoforms, has been implicated in numerous clinical and experimental forms of fibrosis and regulates lung morphogenesis. Differential expression of the PDGF-alpha receptor supports distinct roles for Thy-1(-) and Thy-1(+) fibroblast populations in developmental and fibrotic processes in the lung.

Induction of tenascin in rat lungs undergoing bleomycin-induced pulmonary fibrosis.

Lung injury induced by bleomycin is associated with early inflammation and subsequent excessive deposition of extracellular matrix. In the present study, we investigated the expression of extracellular matrix glycoprotein tenascin (TN) during pulmonary injury induced by bleomycin. After the initial lung injury induced by intratracheal bleomycin instillation, TN and collagen type III (COL III) mRNAs were greatly induced. The pattern of induction of TN was distinct from that of COL III. TN was primarily induced during the early inflammatory phase, whereas the increase in COL III synthesis continued during the reparative phase. The induction and localization of TN mRNA during bleomycin-induced pulmonary injury were also examined by in situ hybridization. TN mRNA was focally induced in rat lungs 3 days after bleomycin administration. Induction of TN mRNA was spatially restricted in the areas of tissue inflammation. The interstitial cells in alveolar septal walls and secondary septal tips in the areas of tissue damage were the major source of TN mRNA production. Expression of TN mRNA was decreased as the inflammation attenuated and development of fibrosis proceeded. Immunocytochemical analyses of TN protein distribution in the lung yielded corroborative results. Immunoreactive TN protein was found in a patchy distribution in alveolar septal walls and secondary septal tips in the areas of damaged tissues. This study demonstrated that TN is a unique early-response extracellular matrix component to bleomycin-induced pulmonary injury and is induced at the sites of the inflammation, suggesting a potential role of TN as a modulator of pulmonary inflammation and repair.

Radioscaphocapitate ligament of the wrist: volar filling defect during radiocarpal arthrography.

PURPOSE: To determine whether a filling defect seen at radiocarpal arthrography represents the volar radioscaphocapitate ligament and to establish how frequently this finding is seen in patients referred for wrist arthrography. MATERIALS AND METHODS: Radiopaque markers were surgically placed along the borders of the radioscaphocapitate ligament in three cadaveric wrist specimens. Each cadaveric wrist was examined at arthrography. Seventy contrast material-enhanced wrist arthrograms were retrospectively reviewed for visualization of the radioscaphocapitate ligament. The arthrographic appearance of the ligament was compared with its reported appearance at dissection, radiography, and magnetic resonance arthrography. RESULTS: The cadaveric study, together with an analysis of the appearance of the ligament, confirmed that the radioscaphocapitate ligament can be seen as a filling defect at radiocarpal arthrography. Fifty-five (78%) of the 70 clinical arthrograms unequivocally demonstrated the radioscaphocapitate ligament. The ligament was most conspicuous early during the injection, especially with the wrist in ulnar deviation. CONCLUSION: The radioscaphocapitate ligament of the wrist can be visualized during routine radiocarpal arthrography. Future studies will need to determine whether abnormalities of the radioscaphocapitate ligament can be diagnosed at arthrography.

Surfactant proteins A and D increase in response to intratracheal lipopolysaccharide.

Surfactant proteins A (SP-A) and D (SP-D) are "collectins": proteins with collagen-like region and lectin domain that bind carbohydrates in a calcium-dependent manner. Mannose-binding protein, a serum collectin, is an acute-phase protein. We hypothesized that SP-A and SP-D would respond to an acute stress, such as lung inflammation, in the same manner as does mannose-binding protein, with increased messenger ribonucleic acid (mRNA) and protein production. Rats received intratracheal lipopolysaccharide (LPS; 0.5 mg/kg) or vehicle and were killed 1, 6, 24, and 72 h later. Their lungs were lavaged and the lung tissue homogenized and analyzed for SP-A, SP-D, and phospholipids. Tissue levels of SP-A were increased by 6 h, peaked at 24 h, and were still elevated at 72 h in LPS-treated animals as compared with those given vehicle. SP-A and SP-D levels in lavage fluid were significantly elevated at 72 h. Message levels for SP-A and SP-D, but not SP-B, were significantly increased at 24 h. Lavage phospholipid levels first increased, then decreased in both the control and LPS-treated animals, and significantly less phospholipid was recovered in the lavage fluid of the LPS-treated animals than in that of controls at 72 h. Although other mechanisms, including altered surfactant metabolism, may be involved, these data are consistent with our hypothesis that SP-A and SP-D are upregulated by an acute inflammatory stress in a manner analogous to that of the structurally and functionally related serum acute-phase reactant, mannose-binding protein. We speculate that this upregulation may be a protective response for the lungs.

Surfactant protein A protects growing cells and reduces TNF-alpha activity from LPS-stimulated macrophages.

In addition to its effect on surfactant lipids, surfactant protein (SP)-A promotes host defense. To define further the role of SP-A in regulating immune cell function, we evaluated the effect of SP-A on lipopolysaccharide (LPS)-activated alveolar macrophages in two settings. First, cocultured LPS-activated macrophages significantly inhibited lung fibroblast growth, but SP-A (added daily) attenuated this effect. Both LPS and SP-A acted via macrophages rather than directly on the fibroblasts, at least partially by affecting tumor necrosis factor (TNF)-alpha activity. TNF-alpha reproduced the growth suppression, anti-TNF-alpha antibodies attenuated the effect LPS-activated macrophages, and SP-A reduced TNF-alpha activity in conditioned medium. Second, SP-A reduced TNF-alpha activity in medium from isolated LPS-stimulated macrophages. The effects of SP-A were noted with or without serum, were dose-dependent and reversible, and were seen with two different serotypes of smooth LPS. Equimolar concentrations of immunoglobulin G and C1q had no effect. Thus SP-A both enhances host defense and modulates immune functions of alveolar macrophages.

Thy1 (+) and (-) lung fibrosis subpopulations in LEW and F344 rats.

Appreciation of the potential of fibroblasts as effector cells in inflammation has led to the recognition of fibroblast subpopulations, the most stable of which are the Thy1 (+) and Thy1 (-) subpopulations in mouse lung fibroblasts. We investigated the presence of Thy1 (+) and (-) fibroblasts in rats, comparing the percentage in primary cultures from rats with different susceptibility to fibrosis, and whether the characteristics were similar in mice and rats, and between normal and fibrotic rats lungs. Using primary cultures of rat fibroblasts obtained both from normal and fibrotic lungs, we analysed the percentage of Thy1 (+) and (-) fibroblasts by fluorescence-activated cell sorter (FACS) analysis. We sorted the fibroblasts to evaluate immune region associated antigen (Ia) expression, which tends to be raised in tissues involved in inflammation, and other characteristics. We found that Thy1 (+) and (-) fibroblasts: 1) are distinct subpopulations in rat lungs; 2) are found in different proportions in rat strains with different propensity towards lung fibrosis; and 3) have similar but not identical characteristics in mice and rats. We also found that bleomycin-induced fibrosis increases the percentage of Ia expression in Thy1 (-), but not Thy1 (+) fibroblasts. The presence of these stable fibroblast supopulations in multiple species, and the fact that these fibroblasts differ in their response to a fibrosing agent, suggests the importance of considering fibroblast subpopulations in development and disease.

Infection-induced airway fibrosis in two rat strains with differential susceptibility.

Chronic infections play a significant role in the morbidity and mortality of patients with chronic airflow limitation. By stimulating airway inflammation, persistent infection has the potential to cause airway fibrosis. However, in patient this condition is most typically found in lungs damaged by other factors, such as smoking, abnormal secretions, or barotrauma. We report the characterization of Mycoplasma pulmonis infection-induced lung fibrosis in two immunocompetent rat strains with no preexisting lung disease. The fibrosis was predominantly in the airways, as demonstrated by the findings for infected animals of increased airway inflammation, airway fibrosis, and airway wall thickness, which correlated with the collagen content of the lungs. Also, the physiological alterations were the opposite of those found in interstitial fibrosis, with a positive correlation between lung compliance and collagen content. The airway fibrosis was noted earlier and to a greater extent in Lewis rats than in Fisher rats, and this result apparently was related to regulation of the inflammatory response. Airway wall thickness, airway inflammation, and airway fibrosis are commonly reported in tissue specimens from patients with chronic airway diseases and have been shown to correlate with airflow limitation in patients with chronic obstructive pulmonary disease. Thus, this model may be useful in furthering our understanding of the role of chronic infection and airway inflammation in airflow obstruction.

Efficacy of clarithromycin against Mycoplasma pneumoniae.

The in-vitro susceptibility of Mycoplasma pneumoniae to clarithromycin, a new macrolide, was compared with that to erythromycin. A broth microdilution assay was used to evaluate 30 clinical isolates collected over a 15 year period from four countries (United States, Australia, Denmark and Japan). Clarithromycin inhibited the growth of all M. pneumoniae strains at low concentrations (less than or equal to 0.008 mg/l) similarly to erythromycin (less than or equal to 0.008 mg/l). In 120 outpatients with radiographically confirmed community acquired pneumonia (mean age 46.2 years), M. pneumoniae was detected culturally and/or serologically by ELISA and immunoblotting in 13% of patients, thus confirming the continued importance of this organism as a respiratory pathogen. M. pneumoniae isolates from these patients were shown to be equally susceptible to clarithromycin (less than or equal to 0.008 mg/l) and erythromycin (less than or equal to 0.008 mg/l). Both clarithromycin and erythromycin were effective in the treatment of community-acquired pneumonia. There were no statistically significant or clinically important differences between the two treatment groups with respect to clinical or radiographic resolution of disease or improvement in signs and symptoms. While the number of clinically evaluable patients with M. pneumoniae infections was small, both macrolides seemed equally effective.

Intussusception of the appendix in a patient with cystic fibrosis.

This case report describes the clinical presentation and the radiographic, endoscopic, and pathologic findings in a patient with cystic fibrosis (CF) and intussusception of the appendix. This is the first time that intussusception of the appendix has been documented in a patient with CF. This disorder should be considered in the CF patient with cramping lower abdominal pain or rectal bleeding.

Single-dose pharmacokinetics of imipenem in children.

The single-dose pharmacokinetics of imipenem (N-formimidoyl thienamycin) was evaluated in 13 pediatric patients (mean age 5.2 +/- 3.5 years). Imipenem was administered in combination with cilastatin as either a 10 mg/kg or 25 mg/kg dose (not to exceed 500 mg) over 15 minutes. Plasma disposition in children was best described by a two-compartment open model. The distribution phase was rapid (t1/2 lambda 1 = 0.18 hours) and was followed by a monoexponential elimination phase (t1/2 lambda 2 = 1.2 hours). The calculated value for the apparent volume of distribution (0.66 L/kg) was similar to that of total body water. The total plasma clearance was rapid (0.36 L/hr/kg). Direct proportionality was exhibited between administered dose and either resultant plasma concentration or area under the plasma concentration versus time curve. Comparison of imipenem plasma pharmacokinetic data derived from these children with data reported from adult subjects revealed disparities for both the apparent volume of distribution and plasma clearance. Based on preliminary pharmacokinetic simulations using parameters generated from our study, a 25.0 mg/kg dose of imipenem administered every 6 hours appears adequate for initiation of therapy in children.

The excretion of sugars in human urine.

Normal humans excrete about 1 mmol of alditols mostly as mannitol and 1 mmol of neutral sugars chiefly allulose in a 24-h period.