Distinctive gut microbiomes of ankylosing spondylitis and inflammatory bowel disease patients suggest differing roles in pathogenesis and correlate with disease activity.

BACKGROUND: Multiple studies have confirmed dysbiosis in ankylosing spondylitis (AS) and inflammatory bowel disease (IBD); however, due to methodological differences across studies, it has not been possible to determine if these diseases have similar or different gut microbiomes. RESULTS: In this study, faecal and intestinal biopsies were obtained from 33 Australian AS patients (including 5 with concomitant IBD, 'AS-IBD'), 59 IBD patients and 105 healthy controls. Stool samples were also obtained from 16 Italian AS patients and 136 Swedish AS patients. Focusing on the Australian cohort, AS, AS-IBD and IBD patients differed from one another and from healthy controls in both alpha and beta diversity. AS patients with and without clinical IBD could be distinguished from one another with moderate accuracy using stool microbiome (AUC=0.754). Stool microbiome also accurately distinguished IBD patients from healthy controls (AUC=0.757). Microbiome composition was correlated with disease activity measured by BASDAI and faecal calprotectin (FCP) levels. Enrichment of potentially pathogenic Streptococcus was noted in AS, AS-IBD and IBD patients. Furthermore, enrichment of another potentially pathogenic genus, Haemophilus, was observed in AS, AS-IBD, IBD, AS patients with increased BASDAI, and IBD patients with faecal calprotectin >100 µg/mg. Apart from these genera, no other taxa were shared between AS and IBD patients. CONCLUSIONS: In conclusion, the distinct gut microbiome of AS and AS-IBD patients compared to IBD patients and healthy controls is consistent with immunological and genetic evidence suggesting that the gut plays a different role in driving AS compared with IBD. However, enrichment of two potentially pathogenic genera in both diseases suggests that the presence of a shared/common microbial trigger of disease cannot be discounted.

Supporting individuals with intellectual and developmental disability during the first 100 days of the COVID-19 outbreak in the USA.

BACKGROUND: It is unknown how the novel Coronavirus SARS-CoV-2, the cause of the current acute respiratory illness COVID-19 pandemic that has infected millions of people, affects people with intellectual and developmental disability (IDD). The aim of this study is to describe how individuals with IDD have been affected in the first 100 days of the COVID-19 pandemic. METHODS: Shortly after the first COVID-19 case was reported in the USA, our organisation, which provides continuous support for over 11 000 individuals with IDD, assembled an outbreak committee composed of senior leaders from across the health care organisation. The committee led the development and deployment of a comprehensive COVID-19 prevention and suppression strategy, utilising current evidence-based practice, while surveilling the global and local situation daily. We implemented enhanced infection control procedures across 2400 homes, which were communicated to our employees using multi-faceted channels including an electronic resource library, mobile and web applications, paper postings in locations, live webinars and direct mail. Using custom-built software applications enabling us to track patient, client and employee cases and exposures, we leveraged current public health recommendations to identify cases and to suppress transmission, which included the use of personal protective equipment. A COVID-19 case was defined as a positive nucleic acid test for SARS-CoV-2 RNA. RESULTS: In the 100-day period between 20 January 2020 and 30 April 2020, we provided continuous support for 11 540 individuals with IDD. Sixty-four per cent of the individuals were in residential, community settings, and 36% were in intermediate care facilities. The average age of the cohort was 46 ± 12 years, and 60% were male. One hundred twenty-two individuals with IDD were placed in quarantine for exhibiting symptoms and signs of acute infection such as fever or cough. Sixty-six individuals tested positive for SARS-CoV-2, and their average age was 50. The positive individuals were located in 30 different homes (1.3% of total) across 14 states. Fifteen homes have had single cases, and 15 have had more than one case. Fifteen COVID-19-positive individuals were hospitalised. As of 30 April, seven of the individuals hospitalised have been discharged back to home and are recovering. Five remain hospitalised, with three improving and two remaining in intensive care and on mechanical ventilation. There have been three deaths. We found that among COVID-19-positive individuals with IDD, a higher number of chronic medical conditions and male sex were characteristics associated with a greater likelihood of hospitalisation. CONCLUSIONS: In the first 100 days of the COVID-19 outbreak in the USA, we observed that people with IDD living in congregate care settings can benefit from a coordinated approach to infection control, case identification and cohorting, as evidenced by the low relative case rate reported. Male individuals with higher numbers of chronic medical conditions were more likely to be hospitalised, while most younger, less chronically ill individuals recovered spontaneously at home.

Autofluorescence lifetime augmented reality as a means for real-time robotic surgery guidance in human patients.

Due to loss of tactile feedback the assessment of tumor margins during robotic surgery is based only on visual inspection, which is neither significantly sensitive nor specific. Here we demonstrate time-resolved fluorescence spectroscopy (TRFS) as a novel technique to complement the visual inspection of oral cancers during transoral robotic surgery (TORS) in real-time and without the need for exogenous contrast agents. TRFS enables identification of cancerous tissue by its distinct autofluorescence signature that is associated with the alteration of tissue structure and biochemical profile. A prototype TRFS instrument was integrated synergistically with the da Vinci Surgical robot and the combined system was validated in swine and human patients. Label-free and real-time assessment and visualization of tissue biochemical features during robotic surgery procedure, as demonstrated here, not only has the potential to improve the intraoperative decision making during TORS but also other robotic procedures without modification of conventional clinical protocols.

Human Factors Results for Fentanyl Iontophoretic Transdermal System (ITS) With Enhanced Controller for Postoperative Pain Management.

PURPOSE: The purpose of this analysis was to conduct summative usability evaluations, including behavioral and subjective evaluations, for the fentanyl iontophoretic transdermal system (ITS). DESIGN: Four usability studies were conducted in representative users. METHODS: The first three studies were conducted with (1) health care professionals (HCPs; N = 31), (2) patients who received placebo fentanyl ITS (N = 30), and (3) healthy volunteers (N = 30), and focused on the understanding and use of fentanyl ITS. The fourth study included HCPs (N = 31) and healthy volunteers (N = 30), and focused on the effectiveness of formal training regarding the use of fentanyl ITS. FINDINGS: Overall, user groups found the fentanyl ITS easy to use. There were no use errors that could potentially have safety implications. In the three early studies, there were some minor difficulties experienced; however, the introduction of a structured training reduced these difficulties. CONCLUSIONS: Patients, nurses, and pharmacists were able to use fentanyl ITS with ease.

High Body Mass Index and Use of Fentanyl Iontophoretic Transdermal System in Postoperative Pain Management: Results of a Pooled Analysis of Six Phase 3/3B Trials.

INTRODUCTION: Postoperative pain management can be challenging in patients with a high body mass index (BMI) especially as a result of poor venous access and delayed ambulation that can result in serious complications. Fentanyl iontophoretic transdermal system (ITS) is a needle-free, patient-controlled analgesic method available for use in acute postoperative pain. The primary objective of these analyses was to determine if there were any differences between patients with high BMI (>40 kg/m2) and lower BMIs (<30 kg/m2 and 35-40 kg/m2) in terms of efficacy or safety. METHODS: Data from three registration, placebo-controlled trials and three active-comparator trials using fentanyl ITS (IONSYS®, The Medicines Company, Parsippany, NJ) for the management of postoperative pain were analyzed using BMI categories of <35 kg/m2, 35-40 kg/m2, and >40 kg/m2. The majority of patients had lower abdominal or orthopedic surgery. For these analyses, the primary efficacy variables were assessed via patient global assessment of pain control (PGA) at 24 h and investigator global assessment (IGA) at study discharge. PGA and IGA are categorical 4-point scales (excellent, good, fair, or poor) with treatment "success" defined as either excellent or good. Safety was evaluated via treatment emergent adverse events (TEAEs). RESULTS: There were 1403 patients randomly assigned and treated with fentanyl ITS for at least 3 h (BMI <35 kg/m2: 1180; 35-40 kg/m2: 136, BMI >40 kg/m2: 85; and 2 missing). PGA treatment success, which evaluates the method of pain control, at 24 h was consistent in the high and low BMI groups in patients treated with fentanyl ITS (<35 kg/m2: 946/1180 [80.2%]; 35-40 kg/m2: 103/136 [75.7%]; and >40 kg/m2: 65/85 [76.5%]). The IGA results at study discharge were similar to the PGA. Safety appeared similar with fentanyl ITS across the BMI groups. CONCLUSION: In these analyses, fentanyl ITS was as efficacious, as assessed by the PGA ratings of treatment "success", in patients with high BMI (>40 kg/m2) as it was for those with lower BMIs (<35 kg/m2 or 35-40 kg/m2) and was generally well tolerated across all BMI categories.

Pharmacokinetic characteristics of fentanyl iontophoretic trandermal system over a range of applied current.

OBJECTIVE: To evaluate the pharmacokinetic (PK) characteristics of a modified fentanyl iontophoretic transdermal system (ITS). RESEARCH DESIGN AND METHODS: This was a prospective, open-label, single-center, randomized, 3-period, 5-treatment, 6-sequence study. Each subject was randomly assigned to receive three treatments in a sequence consisting of intravenous fentanyl citrate, fentanyl ITS at 170 µA, and then one of three other fentanyl ITS treatments at 140, 200 or 230 µA. MAIN OUTCOME MEASURES: The following PK parameters were determined: Cmax, tmax, t1/2, AUC23 - 25 and amount of fentanyl absorbed into systemic circulation (i.e., Dose Absorbed). RESULTS: Fifty-two subjects received at least one fentanyl treatment. Serum exposure (Cmax and AUC23 - 25) and Dose Absorbed increased with increasing current. The median tmax ranged from 23.0 to 23.2 h across the 4 ITS groups. Mean t1/2 values ranged from 11.0 to 13.0 h. The Dose Absorbed from the fentanyl ITS at 170 µA met bioequivalence criteria when compared to data from an earlier version of the fentanyl ITS. CONCLUSIONS: Exposure of fentanyl and the amount of fentanyl absorbed increased with the magnitude of applied current with the ITS. The fentanyl ITS at 170 µA is bioequivalent to an earlier version of the system.

The effect of size ratio on the sphere structure factor in colloidal sphere-plate mixtures.

Binary mixtures of colloidal particles of sufficiently different sizes or shapes tend to demix at high concentration. Already at low concentration, excluded volume interactions between the two species give rise to structuring effects. Here, a new theoretical description is proposed of the structure of colloidal sphere-plate mixtures, based on a density expansion of the work needed to insert a pair of spheres and a single sphere in a sea of them, in the presence or not of plates. The theory is first validated using computer simulations. The predictions are then compared to experimental observations using silica spheres and gibbsite platelets. Small-angle neutron scattering was used to determine the change of the structure factor of spheres on addition of platelets, under solvent contrast conditions where the platelets were invisible. Theory and experiment agreed very well for a platelet/sphere diameter ratio D∕d = 2.2 and reasonably well for D∕d = 5. The sphere structure factor increases at low scattering vector Q in the presence of platelets; a weak reduction of the sphere structure factor was predicted at larger Q, and for the system with D∕d = 2.2 was indeed observed experimentally. At fixed particle volume fraction, an increase in diameter ratio leads to a large change in structure factor. Systems with a larger diameter ratio also phase separate at lower concentrations.

Structure of colloidal sphere-plate mixtures.

In addition to containing spherical pigment particles, coatings usually contain plate-like clay particles. It is thought that these improve the opacity of the paint film by providing an efficient spacing of the pigment particles. This observation is counterintuitive, as suspensions of particles of different shapes and sizes tend to phase separate on increase of concentration. In order to clarify this matter a model colloidal system is studied here, with a sphere-plate diameter ratio similar to that found in paints. For dilute suspensions, small angle neutron scattering revealed that the addition of plates leads to enhanced density fluctuations of the spheres, in agreement with new theoretical predictions. On increasing the total colloid concentration the plates and spheres phase separate due to the disparity in their shape. This is in agreement with previous theoretical and experimental work on colloidal sphere-plate mixtures, where one particle acts as a depleting agent. The fact that no large scale phase separation is observed in coatings is ascribed to dynamic arrest in intimately mixed, or possibly micro-phase separated structures, at elevated concentration.

Predictability of intranasal pharmacokinetics in man using pre-clinical pharmacokinetic data with a dopamine 3 receptor agonist, PF-219061.

(R)-3-(4-propylmorpholin-2-yl) phenol (PF-219061) is a potent, selective agonist of the dopamine 3 receptor for the treatment of female sexual dysfunction. In vivo, PF-219061 exhibits liver blood flow clearance in both rat and dog. Oral bioavailability was 0.7% in dog and less than 5% in rat. Intranasal dosing was investigated to improve bioavailability. Pre-clinical assessments in rat and dog demonstrated intranasal bioavailabilities of 16-38% in rat and 54-61% in dog with very rapid absorption. It was predicted that an intranasal dose in man would give approximately 25-50% bioavailability. The clinical data verified the preclinical predictions demonstrating rapid absorption and approximately dose-proportional increases in exposure. The intranasal bioavailability in man was estimated to be 26-38%. These findings indicate the potential utility of intranasal dosing as a route that circumvents the first-pass effects for PF-219061 resulting in high exposures.

The kallikrein-kinin system in diabetic retinopathy: lessons for the kidney.

Diabetic retinopathy and diabetic nephropathy are common microvascular complications of diabetes. The kallikrein-kinin system (KKS) has been implicated in the development of both conditions, and, in particular, bradykinin and its receptors have been shown to exert angiogenic and proinflammatory actions. Several of the key processes that underlie the development of diabetic retinopathy, such as increased vascular permeability, edema, neovascularization, and inflammatory changes, have been associated with the KKS, and recent work has shown that components of the KKS, including plasma kallikrein, factor XIIa, and high-molecular-weight kininogen, are present in the vitreous of people with diabetic retinopathy. The role of the KKS in the development of diabetic nephropathy is controversial, with both adverse and protective effects of bradykinin and its receptors reported. The review examines the role of the KKS in pathways central to the development of diabetic retinopathy and compares this with reported actions of this system in diabetic nephropathy. The possibility of therapeutic intervention targeting bradykinin and its receptors as treatment for diabetic microvascular conditions is considered.

Leptin improves pulmonary bacterial clearance and survival in ob/ob mice during pneumococcal pneumonia.

The adipocyte-derived hormone leptin is an important regulator of appetite and energy expenditure and is now appreciated for its ability to control innate and adaptive immune responses. We have reported previously that the leptin-deficient ob/ob mouse exhibited increased susceptibility to the Gram-negative bacterium Klebsiella pneumoniae. In this report we assessed the impact of chronic leptin deficiency, using ob/ob mice, on pneumococcal pneumonia and examined whether restoring circulating leptin to physiological levels in vivo could improve host defences against this pathogen. We observed that ob/ob mice, compared with wild-type (WT) animals, exhibited enhanced lethality and reduced pulmonary bacterial clearance following Streptococcus pneumoniae challenge. These impairments in host defence in ob/ob mice were associated with elevated levels of lung tumour necrosis factor (TNF)-alpha, macrophage inflammatory peptide (MIP)-2 [correction added after online publication 28 September 2007: definition of MIP corrected], prostaglandin E(2) (PGE(2)), lung neutrophil polymorphonuclear leukocyte (PMN) counts, defective alveolar macrophage (AM) phagocytosis and PMN killing of S. pneumoniae in vitro. Exogenous leptin administration to ob/ob mice in vivo improved survival and greatly improved pulmonary bacterial clearance, reduced bacteraemia, reconstituted AM phagocytosis and PMN H(2)O(2) production and killing of S. pneumoniae in vitro. Our results demonstrate, for the first time, that leptin improves pulmonary bacterial clearance and survival in ob/ob mice during pneumococcal pneumonia. Further investigations are warranted to determine whether there is a potential therapeutic role for this adipokine in immunocompromised patients.

Pharmacokinetics and clearance processes of UK-279,276 (rNIF) in rat and dog: comparison with human data.

UK-279,276, or recombinant neutrophil inhibitory factor (rNIF), is a glycoprotein that binds to the human CD11b receptor (IC(50) = <0.5 nM) and inhibits neutrophil binding to vascular endothelial cells. In dogs, the pharmacokinetics of UK-279,276 are non-linear with clearance slowing as dose increases (apparent clearance 0.06 ml min(-1) kg(-1) at 0.l mg kg(-1) decreasing to 0.02 ml min(-1) kg(-1) at 2 mg kg(-1)). The observations are in keeping with human pharmacokinetic data. In rats, clearance is linear (0.07-0.13 ml min(-1) kg(-1)) across a similar dose range (0.006-2.25 mg kg(-1)) compared with dogs and humans. These data indicate that two clearance processes act on UK-279,276 in dogs and humans, but only one clearance process occurs in rats. A non-saturable, low-affinity/high-capacity clearance process is present in all animal species studied as well as in human, and it is believed to be hepatic uptake mediated by the asialoglycoprotein receptor. A second, saturable, clearance process is present in dogs and humans that is not apparent in the rat. This high-affinity/low-capacity process is thought to be mediated by interaction with the CD11b receptor, which is the pharmacological target for this molecule. This hypothesis is supported by the marked species differences seen for the affinity of CD11b for UK-279,276, with dogs and humans having high-affinity (IC(50) = <0.5 nM), whilst the rat affinity is low (IC(50) = 134 nM).

Microprocessor controlled transdermal drug delivery.

Transdermal drug delivery via iontophoresis is reviewed with special focus on the delivery of lidocaine for local anesthesia and fentanyl for patient controlled acute therapy such as postoperative pain. The role of the microprocessor controller in achieving dosimetry, alternating/reverse polarity, pre-programmed, and sensor-based delivery is highlighted. Unique features such as the use of tactile signaling, telemetry control, and pulsatile waveforms in iontophoretic drug delivery are described briefly.

Ciliary neurotrophic factor protects retinal ganglion cells from axotomy-induced apoptosis via modulation of retinal glia in vivo.

Adenoviral-mediated transfer of ciliary neurotrophic factor (CNTF) to the retina rescued retinal ganglion cells (RGCs) from axotomy-induced apoptosis, presumably via activation of the high affinity CNTF receptor alpha (CNTFRalpha) expressed on RGCs. CNTF can also activate astrocytes, via its low affinity leukemia inhibitory receptor beta expressed on mature astrocytes, suggesting that CNTF may also protect injured neurons indirectly by modulating glia. Adenoviral-mediated overexpression of CNTF in normal and axotomized rat retinas was examined to determine if it could increase the expression of several glial markers previously demonstrated to have a neuroprotective function in the injured brain and retina. Using Western blotting, the expression of glial fibrillary acid protein (GFAP), glutamate/aspartate transporter-1 (GLAST-1), glutamine synthetase (GS), and connexin 43 (Cx43) was examined 7 days after intravitreal injections of Ad.CNTF or control Ad.LacZ. Compared to controls, intravitreal injection of Ad.CNTF led to significant changes in the expression of CNTFRalpha, pSTAT(3), GFAP, GLAST, GS, and Cx43 in normal and axotomized retinas. Taken together, these results suggest that the neuroprotective effects of CNTF may result from a shift of retinal glia cells to a more neuroprotective phenotype. Moreover, the modulation of astrocytes may buffer high concentrations of glutamate that have been shown to contribute to the death of RGCs after optic nerve transection.

Evaluation of the role of the asialoglycoprotein receptor in the clearance of UK-279,276 (recombinant neutrophil inhibitory factor).

1. UK-279,276 or recombinant neutrophil inhibitory factor (rNIF) is a glycoprotein that has been investigated as an intravenous treatment for stroke. Previous data indicate that the asialoglycoprotein receptor (ASGPR) in the liver might have a role in the uptake and clearance of UK-279,276 from plasma in rats and dogs. 2. Biliary elimination of sialo UK-279,276 can be inhibited by the co-administration of asialo fetuin, a known substrate for ASGPR. These data are in keeping with sialo UK-279,276 being cleared by ASGPR. 3. In vitro experiments have demonstrated that asialo UK-279,276 (Sialo UK-279,276 treated to remove the sialic acid residues present on the glycans) shows a significantly greater uptake in rat, dog and human precision-cut liver slices than the sialylated protein. The addition of asialo fetuin to precision-cut liver slice incubations (rat, dog and man) containing asialo UK-279,276 reduced the uptake to levels similar to those seen for the sialylated protein. These data support the potential role of the ASGPR in the clearance of UK-279,276 in rat, dog and man.

Pharmacokinetic/pharmacodynamic assessment of the effects of E4031, cisapride, terfenadine and terodiline on monophasic action potential duration in dog.

1. Torsades de pointes (TDP) is a potentially fatal ventricular tachycardia associated with increases in QT interval and monophasic action potential duration (MAPD). TDP is a side-effect that has led to withdrawal of several drugs from the market (e.g. terfenadine and terodiline). 2. The potential of compounds to cause TDP was evaluated by monitoring their effects on MAPD in dog. Four compounds known to increase QT interval and cause TDP were investigated: terfenadine, terodiline, cisapride and E4031. On the basis that only free drug in the systemic circulation will elicit a pharmacological response target, free concentrations in plasma were selected to mimic the free drug exposures in man. Infusion regimens were designed that rapidly achieved and maintained target-free concentrations of these drugs in plasma and data on the relationship between free concentration and changes in MAPD were obtained for these compounds. 3. These data indicate that the free ED50 in plasma for terfenadine (1.9 nM), terodiline (76 nM), cisapride (11 nM) and E4031 (1.9 nM) closely correlate with the free concentration in man causing QT effects. For compounds that have shown TDP in the clinic (terfenadine, terodiline, cisapride) there is little differentiation between the dog ED50 and the efficacious free plasma concentrations in man (< 10-fold) reflecting their limited safety margins. These data underline the need to maximize the therapeutic ratio with respect to TDP in potential development candidates and the importance of using free drug concentrations in pharmacokinetic/pharmacodynamic studies.

Thymosin alpha-1.

The pharmacology, pharmacokinetics, clinical efficacy, adverse effects, and dosage and administration of thymosin alpha-1 (TA1) are reviewed. TA1 is a synthetic polypeptide. The drug is in Phase III trials for the treatment of hepatitis C and in Phase II trials for hepatitis B. Additional possible indications are malignant melanoma, hepatocellular carcinoma, drug-resistant tuberculosis, and DiGeorge's syndrome. TA1 is thought to modulate the immune system by augmenting T-cell function. TA1 may affect thymocytes by stimulating their differentiation or by converting them to active T cells. TA1 is rapidly absorbed, achieving peak serum concentrations within two hours. Blood levels return to baseline within 24 hours, and the serum half-life is approximately 2 hours. TA1's efficacy in hepatitis B has been evaluated in 195 patients in four clinical trials. One study found hepatitis B virus (HBV) DNA clearance at six months in 9 of 17 patients receiving TA1, compared with 10 of 16 patients treated with interferon alfa-2b (IFN-alpha 2b) and 4 of 15 historical controls. An open-label trial found HBV DNA clearance in 53% of patients at six months. A randomized, controlled trial found HBV DNA clearance in 40.6% and 25.6% of patients treated with TA1 for 6 and 12 months, respectively, compared with 9.4% of untreated controls. Efficacy for hepatitis C has been evaluated in 162 patients in three clinical trials. In one trial, the number of patients who achieved normal serum alanine aminotransferase (ALT) levels did not differ significantly between TA1 and placebo. In the other two trials, combination TA1 and IFN-alpha 2b was compared with IFN-alpha 2b alone. One trial found a normal serum ALT level at six months in 71% of patients receiving combination therapy, versus 35% of patients receiving IFN-alpha 2b alone. Hepatitis C virus RNA clearance occurred in 65% of patients treated with combination therapy and 29% of patients treated with IFN-alpha 2b alone. The third trial, comparing combination TA1 and IFN-alpha 2b with IFN-alpha 2b alone and with placebo, found normalization of ALT levels at six months in 37.1% of patients receiving combination therapy, 16.2% of patients receiving IFN-alpha 2b alone, and 2.7% of patients receiving placebo. TA1 is well tolerated. Most studies observed only local irritation at the injection site. For hepatitis B and C, TA1 1.6 mg (900 micrograms/m2) should be administered subcutaneously twice a week. Clinical trials of TA1 for chronic hepatitis B or C have had mixed results. TA1 may be useful as monotherapy for hepatitis B or in combination with IFN-alpha 2b for hepatitis C, but its effects on morbidity and mortality remain to be seen.

Upregulation of gap junctional intercellular communication and connexin 43 expression by cyclic-AMP and all-trans-retinoic acid is associated with glutathione depletion and chemosensitivity in neuroblastoma cells.

PURPOSE: Downregulation of gap junctional intercellular communication (GJIC) has been implicated in carcinogenesis. This is a result of altered expression of connexins, the proteins that mediate GJIC, including connexin 43 (Cx43). Our aim was to evaluate the effect of known inducers of Cx43 on the chemosensitivity of the human neuroblastoma cell line IMR-32 to chemotherapeutic agents. METHODS: We examined the effect of dibutyryl-cyclic AMP (db-cAMP) and all-trans-retinoic acid (tRA) on Cx43 and GJIC, glutathione (GSH) and gamma-glutamyl-cysteine-synthetase (gamma-GCS) levels, and glutathione S-transferase (GST) activity. Finally, we performed cell survival assays to measure the response of IMR-32 cells to the chemotherapeutic drugs doxorubicin, melphalan and bis-chloronitrosourea (BCNU), after treatment with db-cAMP and/or tRA. RESULTS: Exposure to db-cAMP led to the upregulation of GJIC and Cx43 expression and phosphorylation. On the other hand, exposure to tRA led to the upregulation of GJIC but Cx43 expression and phosphorylation were not greatly affected. The combination of both agents was more potent in inducing GJIC in comparison to treatment with db-cAMP or tRA alone. Treatment with db-cAMP, but not with tRA, was associated with a significant increase in the cytotoxic effects of the anticancer drugs doxorubicin, melphalan and BCNU as shown by a decrease in their IC50 values. Concomitant exposure to db-cAMP and tRA, however, had a more pronounced effect on cell sensitization to chemotherapy drugs (particularly doxorubicin) than exposure to db-cAMP or tRA alone. Under the db-cAMP and tRA treatment conditions (which upregulate GJIC and modulate drug response), GSH levels were significantly reduced while the levels of GST and gamma-GCS activities remained unchanged. CONCLUSIONS: This study suggests that GJIC plays a role in cellular drug resistance, and highlights the potential use of GJIC modulators in combination with chemotherapy. Also, this is the first study exploring the ability of both db-cAMP and tRA to enhance cell chemosensitivity.

Endotoxin responsiveness and subchronic grain dust-induced airway disease.

Endotoxin is one of the principal components of grain dust that causes acute reversible airflow obstruction and airway inflammation. To determine whether endotoxin responsiveness influences the development of chronic grain dust-induced airway disease, physiological and airway inflammation remodeling parameters were evaluated after an 8-wk exposure to corn dust extract (CDE) and again after a 4-wk recovery period in a strain of mice sensitive to (C3H/HeBFeJ) and one resistant to (C3H/HeJ) endotoxin. After the CDE exposure, both strains of mice had equal airway hyperreactivity to a methacholine challenge; however, airway hyperreactivity persisted only in the C3H/HeBFeJ mice after the recovery period. Only the C3H/HeBFeJ mice showed significant inflammation of the lower airway after the 8-wk exposure to CDE. After the recovery period, this inflammatory response completely resolved. Lung stereological measurements indicate that an 8-wk exposure to CDE resulted in persistent expansion of the airway submucosal cross-sectional area only in the C3H/HeBFeJ mice. Collagen type III and an influx of cells into the subepithelial area participated in the expansion of the submucosa. Our findings demonstrate that subchronic inhalation of grain dust extract results in the development of chronic airway disease only in mice sensitive to endotoxin but not in mice that are genetically hyporesponsive to endotoxin, suggesting that endotoxin is important in the development of chronic airway disease.