Prophylactic therapy with omeprazole for prevention of equine gastric ulcer syndrome (EGUS) in horses in active training: A meta-analysis.

BACKGROUND: Guidelines regarding the impact and value of prophylaxis or maintenance therapy in equine gastric ulcer syndrome (EGUS) are not well-established or defined. The merits and the magnitude of effects of prophylaxis for spontaneous or recurrent squamous gastric ulceration in horses in training are uncertain. OBJECTIVES: To pool data from randomised controlled trials (RCTs) to eliminate reporting bias and evaluate the efficacy of prophylactic omeprazole in the prevention of EGUS in training horses, and secondarily to compare prophylactic dosages of omeprazole. STUDY DESIGN: Meta-analysis. METHODS: This meta-analysis was conducted according to the recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A systematic literature search identified RCTs comparing omeprazole prophylaxis with sham in prevention of EGUS. Data were analysed using the Mantel-Haenszel test method to calculate risk ratio (RR) or mean difference (MD) with 95% confidence intervals (CIs). Primary outcome was efficacy of prophylaxis. Secondary outcome was endoscopic severity of ulceration. The influence of study characteristics on the outcomes was examined by subgroup analyses. RESULTS: In preventing gastric ulcer occurrence, omeprazole prophylaxis was superior to sham in training horses (7 trials, 566 horses, RR 0.28, 95% CI 0.18-0.43; 23.4% in omeprazole prophylaxis vs. 77.2% in sham; high quality evidence). Prevalence of ulceration was 75.3 and 87.2% in the sham arms of the 1 mg/kg and 2 mg/kg omeprazole groups, respectively. Severity scores were significantly lower for omeprazole vs. sham (mean difference [MD] -1.05; 95% CI -1.35 to -0.69). Subgroup analyses comparing prophylactic omeprazole dosages resulted in a mean difference of -0.94 and -1.60 for the 1 and 2 mg/kg groups, respectively. MAIN LIMITATIONS: Studies showed heterogeneity with regard to prophylactic dose. CONCLUSIONS: Omeprazole prophylaxis in active training horses significantly reduces gastric ulceration compared with no prophylaxis (sham) with the absolute effect of 566 fewer ulcers per 1000 horses treated.

Totally laparoscopic abdominal wall reconstruction: lessons learned and results of a short-term follow-up.

PURPOSE: Totally Laparoscopic Abdominal Wall Reconstruction (TLAWR) combines the laparoscopic component separation and the laparoscopic ventral hernia repair, with the purpose of further increasing the benefits of a minimally invasive procedure. However, neither the patient selection criteria nor the long-term results of this technique have been reported. Our objective is to discuss our experience with five patients who received a TLAWR. METHODS: All patients with a midline incisional hernia who underwent a TLAWR from September 2008 to October 2009 were retrospectively reviewed for early and late postoperative complications. RESULTS: A total of five patients underwent the procedure, with a mean age of 48.6 ± 7.9 years. The mean length of stay was 9.2 ± 5.4 days, and follow-up was 12.3 ± 6.8 months. The mean defect size was 175.8 ± 56.2 cm(2). There were no early or late wound complications. Two patients had an early respiratory complication, and one patient developed a port site hernia and small bowel obstruction early after procedure, which required a re-operation. Three patients (60 %) experienced a recurrence. Possible risk factors for recurrence include previous failed hernia repair, loss of domain, large hernias and close proximity to bony structures. CONCLUSIONS: Although TLAWR is feasible and improves wound complications, it may be associated with higher recurrence. Appropriate patient selection is imperative in order for the patient to benefit from this technique.

Obesity should not influence the management of appendicitis.

BACKGROUND: Obesity implies an adverse effect on outcome after appendectomy. This study aimed to determine whether obese patients with appendicitis should be managed differently than nonobese patients. METHODS: After appendectomy, all patients were enrolled in a prospective clinical pathway and followed from initial presentation to full outpatient recovery. RESULTS: In 1 year, 272 adults underwent appendectomy, 55 (22%) of whom were obese. The obese patients were slightly older (35 vs 33 years; p < 0.001). The time to diagnosis (8.5 vs 8.6 h), and the need for computed tomography (CT) scanning (40% vs 49%) was similar in both populations. The obese patients had similar rates of perforation (35% vs 35%) and laparoscopy (47% vs 41%). The median hospital length of stay (LOS) (2 days) and complications, including wound complications (9.1% vs 10.9%) and intraabdominal abscesses (3.6% vs 3.1%), were similar. Subgroup analysis showed a longer LOS for the obese patients with perforation than for the nonobese patients (6 vs 5.5 days; p = 0.036). CONCLUSION: Obese patients had no greater delay in diagnosis, had no greater need for CT scan, gained no additional benefit from laparoscopy, and did not incur significantly worse outcomes after appendectomy except for an increased LOS among those with perforation.

Plasma DNA: a molecular marker of surgical insult and postoperative recovery in esophageal cancer.

AIM: To assess plasma DNA changes intraoperatively, to relate plasma DNA to the magnitude of the surgical insult and to monitor the changes during the postoperative recovery period. MATERIAL AND METHOD: Prospective study of 35 patients with esophageal cancer who had esophagectomy of different magnitudes: 19 esophagectomy without thoracotomy and 16 esophagectomy with thoracotomy. The plasma DNA was measured prior to surgery, throughout the course of the operation on four different intervals, and on postoperative days 1, 3, 5, and 7. RESULTS: A significant difference was seen in the median plasma DNA intraoperatively between the two groups: esophagectomy without thoracotomy, 507 ng/ml/min (range 211-2,708), esophagectomy with thoracotomy, median 1,098 ng/ml/min (range 295-22,284; p = 0.014). Postoperative complications were identified in 6 patients who demonstrated a significant elevation in plasma DNA on postoperative days 5 and 7. CONCLUSION: Plasma DNA increases during surgery as a result of cell damage and the rise correlates with the magnitude of surgery. The descent of plasma DNA postoperatively correlates with surgical recovery. Elevation of the plasma DNA during the postoperative period correlates with postoperative complications. Plasma DNA is an objective molecular marker of surgical insult and can be used to monitor postoperative recovery after esophagectomy.

CT scan in patients with suspected appendicitis: clinical implications for the acute care surgeon.

OBJECTIVE: To determine the influence of computed tomography (CT) scans on diagnosis and management of patients with suspected appendicitis. METHODS: Retrospective 2-year review of 1,630 patients with suspected appendicitis, categorized into three groups based on the likelihood (Alvarado scores) of having appendicitis. Group 1: low likelihood (Alvarado score < or =4); group 2: intermediate likelihood (Alvarado scores 5-7), and group 3: high likelihood (Alvarado score > or = 8). CT scan utilization, hospital course, and final pathology were retrospectively reviewed. RESULTS: More patients received a CT scan in 2006 as compared with 2005 (60 vs. 52%; p = 0.001). The overall appendectomy rate was similar between the 2 years (57% in 2005 vs. 57% in 2006; p = 0.995). The overall appendectomy rate in patients with a CT was significantly higher as compared with those without (60 vs. 53%; p = 0.002). The appendectomy rate in patients with Alvarado scores < or =4 and no CT scan was significantly lower than in those with a CT scan (12 vs. 48%; p < 0.0001). The overall negative appendectomy rate in patients with a CT scan was similar to that in those without: 31/546 (6%) vs. 23/383 (6%). CONCLUSIONS: CT scan utilization increased the appendectomy rate only in patients with a low clinical suspicion for appendicitis. Preoperative CT scans did not decrease the negative appendectomy rate.

Heating mechanisms in short-pulse laser-driven cone targets.

The fast ignitor is a modern approach to laser fusion that uses a short-pulse laser to initiate thermonuclear burn. In its simplest form the laser launches relativistic electrons that carry its energy to a precompressed fusion target. Cones have been used to give the light access to the dense target core through the low-density ablative cloud surrounding it. Here the ANTHEM implicit hybrid simulation model shows that the peak ion temperatures measured in recent cone target experiments arose chiefly from return current joule heating, mildly supplemented by relativistic electron drag. Magnetic fields augment this heating only slightly, but capture hot electrons near the cone surface and force the hot electron stream into filaments.

Hot-electron surface retention in intense short-pulse laser-matter interactions.

Implicit hybrid plasma simulations predict that a significant fraction of the energy deposited into hot electrons can be retained near the surface of targets with steep density gradients illuminated by intense short-pulse lasers. This retention derives from the lateral transport of heated electrons randomly emitted in the presence of spontaneous magnetic fields arising near the laser spot, from geometric effects associated with a small hot-electron source, and from E fields arising in reaction to the ponderomotive force. Below the laser spot hot electrons are axially focused into a target by the B fields, and can filament in moderate Z targets by resistive Weibel-like instability, if the effective background electron temperature remains sufficiently low. Carefully engineered use of such retention in conjunction with ponderomotive density profile steepening could result in a reduced hot-electron range that aids fast ignition. Alternatively, such retention may disturb a deeper deposition needed for efficient radiography and backside fast ion generation.

90-day repeated inhalation exposure of surfactant Protein-C/tumor necrosis factor-alpha, (SP-C/TNF-alpha) transgenic mice to air pollutants.

Tumor necrosis factor (TNF)-alpha, a cytokine present in inflammed lungs, is known to mediate some of the adverse effects of ozone and inhaled particles. The authors evaluated transgenic mice with constitutive pulmonary expression of TNF-alpha under transcriptional regulation of the surfactant protein-C promoter as an animal model of biological susceptibility to air pollutants. To simulate a repeated, episodic exposure to air pollutants, wild-type and TNF mice inhaled air or a mixture of ozone (0.4 ppm) and urban particles (EHC-93, 4.8 mg/m3) for 4 h, once per week, for 12 consecutive weeks and were sacrificed 20 h after last exposure. TNF mice exhibited chronic lung inflammation with septal thickening, alveolar enlargement, and elevated protein and cellularity in bronchoalveolar lavage fluid (genotype main effect, p < .001). Repeated exposure to pollutants did not result in measurable inflammatory changes in wild-type mice and did not exacerbate the inflammation in TNF mice. The pollutants decreased recovery of alveolar macrophages in tavage fluid of both wild-type and TNF mice (exposure main effect, p < .001). Exacerbation of the rate of protein nitration reactions specifically in the lungs of TNF mice was revealed by the high ratio of 3-nitrotyrosine to L-DOPA after exposure to the air pollutants (Genotype x Exposure factor interaction, p = .014). Serum creatine kinase-MM isoform increased in TNF mice exposed to pollutants (Genotype X Exposure factor interaction, p = .043). The marked pollutant-related nitration in the lungs of the TNF mice reveals basic differences in free radical generation and scavenging in the inflamed lungs in response to pollutants. Furthermore, elevation of circulating creatine kinase-MM isoform specifically in TNF mice exposed to pollutants suggests systemic adverse impacts from lung inflammatory mediators, possibly on muscles and the cardiovascular system.

Retinoic acid fails to reverse emphysema in adult mouse models.

BACKGROUND: Previous work has shown that all-trans-retinoic acid reverses elastase induced emphysema in rats. Since there is currently no effective treatment for pulmonary emphysema, the effect of retinoic acid should be further investigated in other adult species. A study was undertaken using two murine models of emphysema to evaluate the effect of retinoic acid. METHODS: The models used were an elastase induced emphysema model for acute alveolar destruction and a tumour necrosis factor (TNF)-alpha transgenic mouse which exhibits chronic air space enlargement, loss of elastic recoil, increased lung volume, and pulmonary hypertension comparable to human pulmonary emphysema. All-trans-retinoic acid (2 mg/kg) was injected for 12 successive days after the establishment of emphysema. The effects of treatment were evaluated using physiological and morphometric analyses. RESULTS: In contrast to the rat, administration of all-trans-retinoic acid in these murine models did not improve the emphysema. Moreover, worsening of emphysema was observed in TNF-alpha transgenic mice treated with all-trans-retinoic acid. The level of keratinocyte chemoattractant (KC), a CXC chemokine, in bronchoalveolar lavage fluid was increased in TNF-alpha transgenic mice following retinoic acid treatment. These data raise the possibility that retinoic acid causes deterioration of emphysema by promoting inflammation in this model. CONCLUSIONS: In these models, retinoic acid did not show positive effects on emphysema. The effect of retinoic acid in the treatment of pulmonary emphysema remains controversial, and further studies are required to determine its physiological effects under a variety of experimental conditions.

Keratinocyte growth factor-induced proliferation of rat airway epithelium is restricted to Clara cells in vivo.

Keratinocyte growth factor (KGF) is a potent mitogen of pulmonary bronchial and alveolar epithelial cells. However, it is unclear which type(s) of airway epithelial cells (AEC) proliferate(s) in response to KGF. AEC proliferation was induced in rats by either endobronchial instillation of 5 mg recombinant human (rHu) KGF per kg body weight or by adenoviral transfer of the human KGF gene (Ad5-HuKGF). Alterations in terminal airway AEC were followed for up to 7 days after rHuKGF, and for up to 28 days after Ad5-HuKGF. Cell proliferation, as assessed by immunohistochemistry (IHC) for incorporated 5-bromo-2'-deoxyuridine (BrdU) and quantified by stereology, peaked at days 1-2 and was resolved by day 7 after rHuKGF and by day 21 after Ad5-HuKGF. Double immunofluorescence labelling for BrdU or Ki-67 on the one hand, and for Clara cell specific protein 10 (CC10) and calcitonin-gene related peptide on the other hand, demonstrated that Clara cells, not pulmonary neuroendocrine cells, proliferated in response to human KGF. TUNEL (terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labelling) method in conjunction with IHC for MNF116 failed to detect significant numbers of apoptotic AEC. IHC in conjunction with stereology revealed transient phenotypic alterations with a decrease in CC10, an increase in surfactant protein D and an increase in CD44v6 in AEC. The authors conclude that Clara cells responded to human keratinocyte growth factor in vivo by proliferation as well as by changes in protein expression, whereas no significant response was observed in pulmonary neuroendocrine cells. As Clara cells are intimately involved in airway epithelial repair, ion and fluid transport, and modulate lung inflammation, the potential of human keratinocyte growth factor to protect the lung may in part rely on the response of Clara cells.

Endometrial hyperplasia and mineralization in zoo felids treated with melengestrol acetate contraceptives.

Melengestrol acetate (MGA) contraceptives are widely used in zoo felids to regulate fertility and may have deleterious effects on endometrial health. To determine whether MGA exposure was associated with endometrial disease, the genital tracts of 212 zoo felids (99 MGA treated and 113 control) representing 23 species were evaluated. Adenomatous and cystic hyperplasia were prevalent in both MGA-treated (85%) and control (61%) groups, and the risk of developing these lesions increased with age. Treatment with MGA further increased the risk of developing advanced hyperplasia regardless of dose, and treatment for >72 months significantly elevated that risk, whereas parous animals had a lower risk. Endometrial polyps, fibrosis, adenomyosis, and hydrometra occurred in both MGA-treated and control animals. MGA treatment was associated with an increased risk of hydrometra and mineralization but not of adenomyosis, polyps, or fibrosis after adjusting for advanced hyperplasia. Acute or chronic endometritis were associated with advanced hyperplasia but not with MGA treatment. These results indicate that proliferative and inflammatory endometrial lesions are common spontaneous diseases in zoo cats, and MGA contraceptives increase the risk of some diseases. The association of MGA with endometrial lesions that could impair fertility should be considered when using this contraceptive in genetically valuable felids.

Serum surfactant proteins-A and -D as biomarkers in idiopathic pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) has a high mortality rate, and current therapies are only marginally effective. A serum biomarker that predicts clinical outcome would be useful to stage disease, indicate prognosis and the need for aggressive therapy, and help stratify patients for clinical trials. The goals of this study were to determine whether serum levels of surfactant protein-A (SP-A) or surfactant protein-D (SP-D) would distinguish between IPF and other types of interstitial lung disease and whether serum SP-A or SP-D levels predict outcome in patients with IPF. The authors found that serum SP-A and SP-D levels were significantly elevated in patients with IPF and systemic sclerosis compared to sarcoidosis, beryllium disease and normal controls, and that SP-D correlated with radiographic abnormalities in patients with IPF. In addition, the authors found that both serum SP-A and SP-D levels were highly predictive of survival in patients with IPF. This is the largest North American data set of surfactant protein measurements in idiopathic pulmonary fibrosis and the first report using multivariate analysis comparing serum surfactant proteins-A and -D to other commonly measured predictors of survival in idiopathic pulmonary fibrosis. Based on these results, the authors propose that serum surfactant proteins may prove to be useful biomarkers in patients with idiopathic pulmonary fibrosis.

Endoscopic augmentation of the cardia with a biocompatible injectable polymer (Enteryx) in a porcine model.

BACKGROUND: Endoscopic approaches to restore the gastroesophageal barrier in patients with gastroesophageal reflux disease (GERD) are presently undergoing clinical trial. The aim of the study was to demonstrate the feasibility, durability, safety, and antireflux efficacy following augmentation of the cardia with a biocompatible injectable polymer (Enteryx). METHODS: Augmentation was performed in 12 Yucatan mini-pigs. The cardia was injected circumferentially with 1-1.5 ml of Enteryx at three or four sites. Four groups of three animals each were killed at 2, 6, 12, and 24 weeks following augmentation. Gastrointestinal endoscopy and esophageal manometry were performed preoperatively and postoperatively. Competency was determined as the intragastric pressure (yield pressure) and volume (yield volume) needed during gastric distension with air and water to result in equalization of gastric and esophageal pressure. Comparisons were made with a group of noninjected animals (n = 6). RESULTS: All animals had a normal eating pattern; none showed any evidence of vomiting or regurgitation. The median injection volume was 4 ml (range, 1-8). At autopsy, implants were found in 83% of the animals. Intramuscular placement of the implant was durable, whereas sloughing occurred if the implant was placed submucosally. The mechanical properties of sphincter length and pressure were unaffected by the injection. The median yield pressure of the animals that survived for >6 weeks (21.4 mmHg) was significantly greater (p = 0.049) than the animals that survived for <6 weeks (4.5 mmHg) and greater (p = 0.054) than the control animals (9.1 mmHg), suggesting that the healing process was associated with reduced distensibility of the cardia. CONCLUSIONS: Augmentation of the cardia with an injectable polymer (Enteryx) is simple, safe, and durable. Early studies suggest that alteration in the distensibility and geometry of the gastroesophageal junction may provide antireflux protection.

The effects of intravenous anesthetics and lidocaine on proliferation of cultured type II pneumocytes and lung fibroblasts.

UNLABELLED: Type II pneumocytes synthesize surfactant and differentiate into type I pneumocytes to maintain the epithelium (1). Alveolar type II cell proliferation is required for reepithelization after acute lung injury (ALI) and is thought to minimize the subsequent fibrotic response (1). Keratinocyte growth factor (KGF) and hepatocyte growth factor (HGF) are among the most potent mitogen for type II epithelial cells, but not for fibroblasts in the lung (1). These growth factors attenuate several experimental ALI models by promoting epithelial repair (2,3). Thus, KGF and HGF may be a promising therapeutic approach to ALI. Critically ill patients with ALI often receive IV anesthetics or sedatives to facilitate mechanical ventilation. Furthermore, these patients sometimes undergo bronchoscopy under local anesthesia to obtain bronchoalveolar lavage fluid or to remove respiratory secretions. Several IV and local anesthetics inhibit proliferation of various cells including epithelium (4,5). If these anesthetics impede proliferation of type II pneumocytes, this suppressive effect may be a disadvantage for alveolar reepithelization in the course of recovery from ALI. In this study, we examined the effects of midazolam, propofol, ketamine, thiopental, and lidocaine on proliferation of type II alveolar epithelial cells using in vitro culture system. Because fibroblast proliferation is a key event in late phase of ALI, inhibition of this fibroproliferation is probably beneficial. Thus, we further determined whether these anesthetics could regulate proliferation of lung fibroblasts. In the current study, rolipram was used as a positive control. In our previous preliminary experiment, we found that rolipram, a phosphodiesterase inhibitor type IV, augments spontaneous or KGF-/HGF-promoted type II cell proliferation (6). IMPLICATIONS: Midazolam, ketamine, thiopental, propofol, or lidocaine did not inhibit proliferation of cultured rat type II pneumocytes. Our findings suggest that these anesthetics do not impede alveolar reepithelization after acute lung injury.

Predictive factors of Barrett esophagus: multivariate analysis of 502 patients with gastroesophageal reflux disease.

HYPOTHESIS: Risk factors for the presence and extent of Barrett esophagus (BE) can be identified in patients with gastroesophageal reflux disease (GERD). DESIGN: Case-comparison study. SETTING: University tertiary referral center. PATIENTS: Five hundred two consecutive patients with GERD documented by 24-hour esophageal pH monitoring and with complete demographic, endoscopic, and physiological evaluation, divided in groups according to the presence and extent of BE (328 patients without BE and 174 with BE [67 short-segment BE and 107 long-segment BE]). MAIN OUTCOME MEASURES: Clinical, endoscopic, and physiological data, studied by multivariate analysis, to identify the independent predictors of the presence and extent of BE. RESULTS: Seven factors were identified as predictors of BE. They were abnormal bile reflux (odds ratio [OR], 4.2; 95% confidence interval [CI], 1.9-9.7), hiatal hernia larger than 4 cm (OR, 4.1; 95% CI, 2.1-8.0), a defective lower esophageal sphincter (OR, 2.7; 95% CI, 1.4-5.4), male sex (OR, 2.6; 95% CI, 1.6-4.3), defective distal esophageal contraction (OR, 2.2; 95% CI, 1.4-3.5), abnormal number of reflux episodes lasting longer than 5 minutes (OR, 2.2; 95% CI, 1.1-4.6), and GERD symptoms lasting for more than 5 years (OR, 2.1; 95% CI, 1.4-3.2). Only abnormal bile reflux (OR, 4.8; 95% CI, 1.7-13.2) was identified as a predictor of short-segment BE (baseline, no BE). Three factors were identified as predictors of long-segment BE (baseline short-segment BE). They were hiatal hernia larger than 4 cm (OR, 17.8; 95% CI, 4.1-76.6), a defective lower esophageal sphincter (OR, 16.9; 95% CI, 1.6-181.4), and an abnormal longest reflux episode (OR, 8.1; 95% CI, 2.8-24.0). CONCLUSIONS: Among patients with GERD, specific factors are associated with the presence and extent of BE. Elimination of reflux with an antireflux operation in patients with 1 or more of these factors may prevent the future development of BE.

Tumor necrosis factor-alpha negatively regulates airway hyperresponsiveness through gamma-delta T cells.

Tumor necrosis factor (TNF)-alpha is a potent cytokine with immunomodulatory, proinflammatory, and pathobiologic activities. Although TNF-alpha is thought to play a role in mediating airway inflammation and airway hyperresponsiveness (AHR), its function is not well defined. TNF-alpha-deficient mice and mice expressing TNF-alpha in their lungs because of a TNF-alpha transgene placed under the control of the surfactant protein (SP)-C promoter (SP-C/TNF-alpha-transgenic mice) were sensitized to ovalbumin (OVA) and subsequently challenged with OVA via the airways; airway function in response to inhaled methacholine was monitored. In the TNF-alpha-deficient mice, AHR was significantly increased over that in controls. In contrast, the transgenic mice failed to develop AHR. In addition, sensitized/ challenged TNF-alpha-deficient mice had significantly increased numbers of eosinophils and higher levels of interleukin (IL)-5 and IL-10 in their bronchoalveolar lavage fluid than were found for control mice. However, in SP-C/TNF-alpha-transgenic mice, both the numbers of eosinophils and levels of IL-5 and IL-10 were significantly lower than in sensitized/challenged transgene-negative mice. gammadelta T cells have been shown to be activated by TNF-alpha and to negatively regulate AHR. Depletion of gammadelta T cells in the TNF-alpha-transgenic mice in the present study increased AHR, whereas depletion of these cells had no significant effect in TNF-alpha-deficient mice. These data indicate that TNF-alpha can negatively modulate airway responsiveness, controlling airway function in allergen-induced AHR through the activation of gammadelta T cells.

Rat alveolar type II cells inhibit lung fibroblast proliferation in vitro.

Fibroblasts stimulate alveolar type II epithelial cell differentiation and proliferation in vitro and during lung development. However, little is known about the effects of adult type II cells on fibroblasts. We investigated the effect of adult rat type II cells on proliferation of adult human lung fibroblasts. Fibroblasts were suspended within rat tail collagen which was gelled on a floating polycarbonate filter, and type II cells were cultured on Matrigel. In this coculture system, alveolar type II cells inhibited fibroblast proliferation and indomethacin blocked the inhibitory effect on fibroblast growth. Prostaglandin (PG) E2, the major PG secreted by type II cells, inhibited fibroblast proliferation and was increased during the period of inhibition of fibroblast proliferation. Incubation with arachidonate showed that most of the PGE2 in the coculture system was produced by the fibroblasts. In addition, we found that rat type II cells also inhibited rat fibroblasts and that inhibition of fibroblast growth by type II cells could be stimulated by keratinocyte growth factor. We conclude that in this coculture system, type II cells inhibit fibroblast proliferation by secreting a factor(s) that stimulates PGE2 production by fibroblasts, and that PGE2 directly inhibits fibroblast proliferation.

Serological survey for Ehrlichia canis in urban dogs from the major population centres of northern Australia.

OBJECTIVE: To detect evidence of Ehrlichia canis infection of dogs from the major population centres of northern Australia, if present. DESIGN: Serological investigation for E. canis. PROCEDURE: The sera of 316 domestic dogs, collected from the northern Australian population centres of Townsville, Cairns, Darwin, Kununurra and Broome from May 1997 to August 1999, were investigated for evidence of infection with E. canis. Samples were tested for antibodies to E. canis using an indirect fluorescent antibody (IFA) test. The buffy coats from blood of dogs whose serum reacted in the IFA test were subsequently tested with a nested PCR to detect E. canis DNA. When available, blood from these dogs was injected into suckling mice, which were then examined for clinical disease and tested for the presence of E. canis antibodies. RESULTS: Of the 316 samples tested seven reacted in the IFA test for E. canis. None of the dogs from which these samples were obtained exhibited clinical signs of acute or chronic ehrlichiosis. The six positive samples available for testing were negative when tested with the nested PCR. Suckling mice inoculated with blood from three of the dogs whose serum was positive by IFA test showed no signs of clinical disease nor did their give positive reactions in the IFA test. CONCLUSIONS: No evidence of E. canis infection was confirmed in any of the dogs examined. Northern Australia would appear to remain free of this obligate parasite.

Polysaccharide recognition by surfactant protein D: novel interactions of a C-type lectin with nonterminal glucosyl residues.

Surfactant protein D (SP-D), a C-type lectin, is an important pulmonary host defense molecule. Carbohydrate binding is critical to its host defense properties, but the precise polysaccharide structures recognized by the protein are unknown. SP-D binding to Aspergillus fumigatus is strongly inhibited by a soluble beta-(1-->6)-linked but not by a soluble beta-(1-->3)-linked glucosyl homopolysaccharide (pustulan and laminarin, respectively), suggesting that SP-D recognizes only certain polysaccharide configurations, likely through differential binding to nonterminal glucosyl residues. In this study we have computationally docked alpha/beta-D-glucopyranose and alpha/beta-(1-->2)-, alpha/beta-(1-->3)-, alpha/beta-(1-->4)-, and alpha/beta-(1-->6)-linked glucosyl trisaccharides into the SP-D carbohydrate recognition domain. As with the mannose-binding proteins, we found significant hydrogen bonding between the protein and the vicinal, equatorial OH groups at the 3 and 4 positions on the sugar ring. Our docking studies predict that alpha/beta-(1-->2)-, alpha-(1-->4)-, and alpha/beta-(1-->6)-linked but not alpha/beta-(1-->3)-linked glucosyl trisaccharides can be bound by their internal glucosyl residues and that binding also occurs through interactions of the protein with the 2- and 3-equatorial OH groups on the glucosyl ring. By using various soluble glucosyl homopolysaccharides as inhibitors of SP-D carbohydrate binding, we confirmed the interactions predicted by our modeling studies. Given the sequence and structural similarity between SP-D and other C-type lectins, many of the predicted interactions should be applicable to this protein family.

Pulmonary surfactant phosphatidylcholine transport bypasses the brefeldin A sensitive compartment of alveolar type II cells.

Brefeldin A (BFA) causes disassembly of the Golgi apparatus and blocks protein transport to this organelle from the endoplasmic reticulum. However, there still remains considerable ambiguity regarding the involvement of the Golgi apparatus in glycerolipid transport pathways. We examined the effects of BFA upon the intracellular translocation of phosphatidylcholine in alveolar type II cells, that synthesize, transport, store and secrete large amounts of phospholipid for regulated exocytosis. BFA at concentrations as high as 10 microg/ml failed to alter the assembly of phosphatidylcholine into lamellar bodies, the specialized storage organelles for pulmonary surfactant. The same concentration of BFA was also ineffective at altering the secretion of newly synthesized phosphatidylcholine from alveolar type II cells. In contrast, concentrations of the drug of 2.5 microg/ml completely arrested newly synthesized lysozyme secretion from the same cells, indicating that BFA readily blocked protein transport processes in alveolar type II cells. The disassembly of the Golgi apparatus in alveolar type II cells following BFA treatment was also demonstrated by showing the redistribution of the resident Golgi protein MG-160 to the endoplasmic reticulum. These results indicate that intracellular transport of phosphatidylcholine along the secretory pathway in alveolar type II cells proceeds via a BFA insensitive route and does not require a functional Golgi apparatus.