A Comparative Study of Ex-Vivo Murine Pulmonary Mechanics Under Positive- and Negative-Pressure Ventilation

Increased ventilator use during the COVID-19 pandemic resurrected persistent questions regarding mechanical ventilation including the difference between physiological and artificial breathing induced by ventilators (i.e., positive- versus negative-pressure ventilation, PPV vs NPV). To address this controversy, we compare murine specimens subjected to PPV and NPV in ex vivo quasi-static loading and quantify pulmonary mechanics via measures of quasi-static and dynamic compliances, transpulmonary pressure, and energetics when varying inflation frequency and volume. Each investigated mechanical parameter yields instance(s) of significant variability between ventilation modes. Most notably, inflation compliance, percent relaxation, and peak pressure are found to be consistently dependent on the ventilation mode. Maximum inflation volume and frequency note varied dependencies contingent on the ventilation mode. Contradictory to limited previous clinical investigations of oxygenation and end-inspiratory measures, the mechanics-focused comprehensive findings presented here indicate lung properties are dependent on loading mode, and importantly, these dependencies differ between smaller versus larger mammalian species despite identical custom-designed PPV/NPV ventilator usage. Results indicate that past contradictory findings regarding ventilation mode comparisons in the field may be linked to the chosen animal model. Understanding the differing fundamental mechanics between PPV and NPV may provide insights for improving ventilation strategies and design to prevent associated lung injuries.

Continuous Instrument Tracking in a Cerebral Corticectomy Ex Vivo Calf Brain Simulation Model: Face and Content Validation

BACKGROUND AND OBJECTIVES

Subpial corticectomy involving complete lesion resection while preserving pial membranes and avoiding injury to adjacent normal tissues is an essential bimanual task necessary for neurosurgical trainees to master. We sought to develop an ex vivo calf brain corticectomy simulation model with continuous assessment of surgical instrument movement during the simulation. A case series study of skilled participants was performed to assess face and content validity to gain insights into the utility of this training platform, along with determining if skilled and less skilled participants had statistical differences in validity assessment.

METHODS

An ex vivo calf brain simulation model was developed in which trainees performed a subpial corticectomy of three defined areas. A case series study assessed face and content validity of the model using 7-point Likert scale questionnaires.

RESULTS

Twelve skilled and 11 less skilled participants were included in this investigation. Overall median scores of 6.0 (range 4.0-6.0) for face validity and 6.0 (range 3.5-7.0) for content validity were determined on the 7-point Likert scale, with no statistical differences between skilled and less skilled groups identified.

CONCLUSION

A novel ex vivo calf brain simulator was developed to replicate the subpial resection procedure and demonstrated face and content validity.

Toward Estimating MRI-Ultrasound Registration Error in Image-Guided Neurosurgery

Image-guided neurosurgery allows surgeons to view their tools in relation to preoperatively acquired patient images and models. To continue using neuronavigation systems throughout operations, image registration between preoperative images [typically magnetic resonance imaging (MRI)] and intraoperative images (e.g., ultrasound) is common to account for brain shift (deformations of the brain during surgery). We implemented a method to estimate MRI-ultrasound registration errors, with the goal of enabling surgeons to quantitatively assess the performance of linear or nonlinear registrations. To the best of our knowledge, this is the first dense error estimating algorithm applied to multimodal image registrations. The algorithm is based on a previously proposed sliding-window convolutional neural network that operates on a voxelwise basis. To create training data where the true registration error is known, simulated ultrasound images were created from preoperative MRI images and artificially deformed. The model was evaluated on artificially deformed simulated ultrasound data and real ultrasound data with manually annotated landmark points. The model achieved a mean absolute error (MAE) of 0.977 ± 0.988 mm and a correlation of 0.8 ± 0.062 on the simulated ultrasound data, and an MAE of 2.24 ± 1.89 mm and a correlation of 0.246 on the real ultrasound data. We discuss concrete areas to improve the results on real ultrasound data. Our progress lays the foundation for future developments and ultimately implementation of clinical neuronavigation systems.

Diseased and healthy murine local lung strains evaluated using digital image correlation

Tissue remodeling in pulmonary disease irreversibly alters lung functionality and impacts quality of life. Mechanical ventilation is amongst the few pulmonary interventions to aid respiration, but can be harmful or fatal, inducing excessive regional (i.e., local) lung strains. Previous studies have advanced understanding of diseased global-level lung response under ventilation, but do not adequately capture the critical local-level response. Here, we pair a custom-designed pressure-volume ventilator with new applications of digital image correlation, to directly assess regional strains in the fibrosis-induced ex-vivo mouse lung, analyzed via regions of interest. We discuss differences between diseased and healthy lung mechanics, such as distensibility, heterogeneity, anisotropy, alveolar recruitment, and rate dependencies. Notably, we compare local and global compliance between diseased and healthy states by assessing the evolution of pressure-strain and pressure-volume curves resulting from various ventilation volumes and rates. We find fibrotic lungs are less-distensible, with altered recruitment behaviors and regional strains, and exhibit disparate behaviors between local and global compliance. Moreover, these diseased characteristics show volume-dependence and rate trends. Ultimately, we demonstrate how fibrotic lungs may be particularly susceptible to damage when contrasted to the strain patterns of healthy counterparts, helping to advance understanding of how ventilator induced lung injury develops.

IMPACT OF COVID-19 ON THYROID FUNCTION: EVIDENCE FROM IRAN

Context

We assessed the association between the severity of COVID-19 and the thyroid function, and the relationship of thyroid hormones with inflammatory markers in COVID-19 patients.

Subjects and methods

This observational study contained 95 COVID-19 patients. The covariates of interest included the thyroid-stimulating hormone (TSH) and the total form of thyroid hormones thyroxine and triiodothyronine. Furthermore, the inflammatory markers including C-reactive protein, erythrocyte sedimentation rate, lactate dehydrogenase (LDH), and lymphocyte were measured. To analyze the data, the t-test, the nonparametric test for comparing the medians, and the Spearman correlation were used.

Results

The median (interquartile range) of ages was equal to 53 (41-66) years old, including 54 men (56.8%). As the severity of COVID-19 progressed from moderate to severe, increasing, though non-significant, trends of thyroid dysfunction were observed, the most remarkable for TSH. The only significant association between thyroid hormones and inflammatory markers was a Spearman correlation of -0.28 between TSH and LDH. Moreover, a direct association was found between the severity of COVID-19 and the LDH levels (p-value<0.001).

Conclusions

A direct relation between the severity of COVID-19 and the LDH level and a reverse association between the LDH level and the thyroid hormone, TSH was obtained.

Mouse lung mechanical properties under varying inflation volumes and cycling frequencies

Respiratory pathologies alter the structure of the lung and impact its mechanics. Mice are widely used in the study of lung pathologies, but there is a lack of fundamental mechanical measurements assessing the interdependent effect of varying inflation volumes and cycling frequency. In this study, the mechanical properties of five male C57BL/6J mice (29–33 weeks of age) lungs were evaluated ex vivo using our custom-designed electromechanical, continuous measure ventilation apparatus. We comprehensively quantify and analyze the effect of loading volumes (0.3, 0.5, 0.7, 0.9 ml) and breathing rates (5, 10, 20 breaths per minute) on pulmonary inflation and deflation mechanical properties. We report means of static compliance between 5.4–16.1 µl/cmH₂O, deflation compliance of 5.3–22.2 µl/cmH₂O, percent relaxation of 21.7–39.1%, hysteresis of 1.11–7.6 ml•cmH₂O, and energy loss of 39–58% for the range of four volumes and three rates tested, along with additional measures. We conclude that inflation volume was found to significantly affect hysteresis, static compliance, starting compliance, top compliance, deflation compliance, and percent relaxation, and cycling rate was found to affect only hysteresis, energy loss, percent relaxation, static compliance and deflation compliance.

Examining lung mechanical strains as influenced by breathing volumes and rates using experimental digital image correlation

BACKGROUND

Mechanical ventilation is often employed to facilitate breathing in patients suffering from respiratory illnesses and disabilities. Despite the benefits, there are risks associated with ventilator-induced lung injuries and death, driving investigations for alternative ventilation techniques to improve mechanical ventilation, such as multi-oscillatory and high-frequency ventilation; however, few studies have evaluated fundamental lung mechanical local deformations under variable loading.

METHODS

Porcine whole lung samples were analyzed using a novel application of digital image correlation interfaced with an electromechanical ventilation system to associate the local behavior to the global volume and pressure loading in response to various inflation volumes and breathing rates. Strains, anisotropy, tissue compliance, and the evolutionary response of the inflating lung were analyzed.

RESULTS

Experiments demonstrated a direct and near one-to-one linear relationship between applied lung volumes and resulting local mean strain, and a nonlinear relationship between lung pressures and strains. As the applied air delivery volume was doubled, the tissue surface mean strains approximately increased from 20 to 40%, and average maximum strains measured 70-110%. The tissue strain anisotropic ratio ranged from 0.81 to 0.86 and decreased with greater inflation volumes. Local tissue compliance during the inflation cycle, associating evolutionary strains in response to inflation pressures, was also quantified.

CONCLUSION

Ventilation frequencies were not found to influence the local stretch response. Strain measures significantly increased and the anisotropic ratio decreased between the smallest and greatest tidal volumes. Tissue compliance did not exhibit a unifying trend. The insights provided by the real-time continuous measures, and the kinetics to kinematics pulmonary linkage established by this study offers valuable characterizations for computational models and establishes a framework for future studies to compare healthy and diseased lung mechanics to further consider alternatives for effective ventilation strategies.

The effect of CASP3 rs4647610 and rs4647602 polymorphisms on tumour size and cancer stage in papillary thyroid carcinoma

BACKGROUND

Papillary thyroid carcinoma (PTC) is the most frequent form of thyroid cancer whose incidence has increased in recent years. Dysregulated apoptosis is known in the pathogenesis of various cancers. Caspase-3 is an important apoptotic component and its abnormal function may play a key role in cancer pathogenesis. We tested the hypothesis of a link between CASP3 single nucleotide polymorphisms rs4647610 and rs4647602 on PTC and its clinical outcomes.

MATERIAL AND METHODS

A total of 134 PTC patients and 151 healthy controls were genotyped for CASP3 rs4647610 and rs4647602 single nucleotide polymorphisms (SNPs) using PCR-RFLP method.

RESULTS

Allele and genotype frequencies of both SNPs were not different between cases and controls. The combined genotypes and haplotypes were not linked to PTC. However, the frequencies of CASP3 rs4647610 GA and AA genotypes were higher in PTC patients with larger tumour size (≥1 cm), and the rs4647610 SNP was associated with increased tumour size in the dominant model (OR 3.4 [95% CI, 1.1-11], P = 0.04). The CASP3 rs4647602CA and AA genotypes were higher in PTC patients with lower TNM stage (I-II) compared to higher stages (III-IV). No association was observed between CASP3 polymorphisms and other PTC outcomes.

CONCLUSION

Although CASP3 rs4647610 and rs4647602 SNPs are not associated with PTC, rs4647610 is linked to larger tumour size, and rs4647602 to lower stage of cancer.

The Effects of Concurrent Training Order on Satellite Cell-Related Markers, Body Composition, Muscular and Cardiorespiratory Fitness in Older Men with Sarcopenia

OBJECTIVES

Concurrent Training (CT) is described as a combination of resistance training (RT) and endurance training (ET) in a periodized program to maximize all aspects of physical performance. To date, effects of CT order on muscular and cardiorespiratory fitness adaptations are controversial. Owing to the age-related decrement in satellite cells (SC) which are critical for fiber repair, conservation, muscle hypertrophy as well as cardiorespiratory fitness, the present study examined the response of SC related markers to CT order in older sarcopenic men.

PARTICIPANTS

Thirty older men (age= 64.3 ± 3.5 years) were randomly assigned into one of 3 groups, ET followed by RT (E+R; n=10), RT followed by ET (R+E; n= 10) or a control (C; n=10).

INTERVENTION

The training protocol consisted of 3 exercise sessions per week for 8 weeks. Blood samples were obtained at baseline and 48 hours after the final training session.

RESULTS

Weight, skeletal muscle mass, lower and upper body power, maximal oxygen consumption (VO2max), Paired Box 7 (Pax7), and Myogenic factor 5 (Myf5) significantly increased, while were percent body fat significantly decreased following E+R and R+E compared to C. Importantly, the improvement in skeletal muscle mass, lower and upper body power, Myf5 and Pax7 in the E+R was significantly greater than the R+E group. Myogenin (Myog) and Paired Box 3 (Pax3) significantly increased (P < 0.01) in both training groups compared to no changes in C.

CONCLUSION

An 8-week CT intervention improves SC related markers, body composition and enhances power and VO2max in older sarcopenic participants, regardless of the order of RT and ET. However, performing ET before RT may be more effective at enhancing skeletal muscle mass, Myf5 and Pax7, in addition to both lower and upper body power. While both CT programs produced notable physiological and performance benefits, performing ET before RT during CT may provide the greatest therapeutic benefits for aging individuals.

Impact of 3D echocardiography on grading of mitral stenosis and prediction of clinical events

Background

The mitral valve orifice area (MVOA) is difficult to assess accurately by 2D echocardiography because of geometric assumptions; therefore, 3D planimetry may offer advantages. We studied the differences in MVOA measurements between the most frequently used methods, to determine if 3D planimetry would result in the re-grading of severity in any cases, and whether it was a more accurate predictor of clinical outcomes.

Methods

This was a head-to-head comparison of the three most commonly used techniques to grade mitral stenosis (MS) by orifice area and to assess their impact on clinical outcomes. 2D measurements (pressure half-time (PHT), planimetry) and 3D planimetry were performed retrospectively on patients with at least mild MS. The clinical primary endpoint was defined as a composite of MV balloon valvotomy, mitral valve repair or replacement (MVR) and/or acute heart failure (HF) admissions.

Results

Forty-one consecutive patients were included; the majority were female (35; 85.4%), average age 55 (17) years. Mean and peak MV gradients were 9.4 (4) mmHg and 19 (6) mmHg, respectively. 2D and 3D measures of MVOA differed significantly; mean 2D planimetry MVOA was 1.28 (0.40) cm², mean 3D planimetry MVOA 1.15 (0.29) cm² (P = 0.003). Mean PHT MVOA was 1.43 (0.44) cm² (P = 0.046 and P < 0.001 in comparison to 2D and 3D planimetry methods, respectively). 3D planimetry reclassified 7 (17%) patients from mild-to-moderate MS, and 1 (2.4%) from moderate to severe. Overall, differences between the two methods were significant (X², P < 0.001). Only cases graded as severe by 3D predicted the primary outcome measure compared with mild or moderate cases (odds ratio 5.7).

Conclusion

3D planimetry in MS returns significantly smaller measurements, which in some cases results in the reclassification of severity. Routine use of 3D may significantly influence the management of MS, with a degree of prediction of clinical outcomes.

Contrast echocardiography in daily clinical practice

Ultrasound contrast agents have unique acoustic properties that enable them to enhance the cardiac blood flow and thus are used broadly in modern echocardiography laboratories for salvage of nondiagnostic studies, improving accuracy and reducing variability even in the presence of adequate image quality. Contrast echocardiography is also used as an adjunctive technique when unenhanced echocardiography falls short in the differentiation of cardiac structural abnormalities such as cardiac masses. Ultrasound contrast agents are pure intravascular tracers. Development of innovative ultrasound imaging techniques has led to myocardial perfusion imaging with contrast echocardiography. Although currently an off-label indication, it has been shown that perfusion imaging with contrast echocardiography adds incremental value to stress echocardiography in the detection of coronary artery disease. Moreover, it can be used for assessment of myocardial viability. In this paper we briefly discuss the basics of contrast echocardiography and its use in daily clinical practice.

Optimizing landfill site selection by using land classification maps

Municipal solid waste disposal is a major environmental concern throughout the world. Proper landfill siting involves many environmental, economic, technical, and sociocultural challenges. In this study, a new quantitative method for landfill siting that reduces the number of evaluation criteria, simplifies siting procedures, and enhances the utility of available land evaluation maps was proposed. The method is demonstrated by selecting a suitable landfill site near the city of Marvdasht in Iran. The approach involves two separate stages. First, necessary criteria for preliminary landfill siting using four constraints and eight factors were obtained from a land classification map initially prepared for irrigation purposes. Thereafter, the criteria were standardized using a rating approach and then weighted to obtain a suitability map for landfill siting, with ratings in a 0-1 domain and divided into five suitability classes. Results were almost identical to those obtained with a more traditional environmental landfill siting approach. Because of far fewer evaluation criteria, the proposed weighting method was much easier to implement while producing a more convincing database for landfill siting. The classification map also considered land productivity. In the second stage, the six best alternative sites were evaluated for final landfill siting using four additional criteria. Sensitivity analyses were furthermore conducted to assess the stability of the obtained ranking. Results indicate that the method provides a precise siting procedure that should convince all pertinent stakeholders.

Evaluation of the antimicrobial effect of conventional and nanosilver-containing varnishes on oral streptococci

STATEMENT OF THE PROBLEM

Nanosilver particles have the potential to serve as a bactericidal agent because of the inherent antimicrobial influences of silver ion. The literature confirmed that specific micro-organisms, especially streptococci, have an important role as an etiological factor for caries.

PURPOSE

The aim of this study was to evaluate the antimicrobial effect of conventional and nanosilver-containing varnishes on oral streptococci.

MATERIALS AND METHOD

Pure cultivations of Streptococcus mutans and Streptococcus salivarius were prepared on blood agar media. Thereafter, 0.5 McFarland standard of recently grown bacteria in normal saline was prepared and the bacteria were cultivated monotonously on the culture medium surface by applying a swab. Different concentrations of nanosilver varnishes were prepared in the Mueller- Hinton broth medium in the test tubes and equal amounts of 0.5 McFarland suspension of all the tested bacteria were added separately to all test tubes. A tube without varnish was included as the control sample. The tubes were kept at 37°C for 24 hours, then cultured to determine the numbers of bacteria in each tube by counting colonies. The numbers of bacteria in tubes with varnish were compared to the numbers of bacteria in the tube without varnish. In the instance of observing any reduction in the growth, the minimum inhibitory concentration for growth in the tube with varnish was determined.

RESULTS

Nanosilver varnish had an antimicrobial effect on S. mutans and S. salivarius.  S. salivarius was more susceptible than S. mutans to the nanosilver varnish.

CONCLUSION

Based on the results of this study, nanosilver varnishes can be used under amalgam restorations to reduce microbial population and subsequently preventing the recurrent caries.

Ultrasonic assisted synthesis of imidazo[1,2-a]azine catalyzed by ZnO nanorods

ZnO nanorods have been successfully used as an efficient, economic, and reusable catalyst for the synthesis of imidazo[1,2-a]azine under ultrasonic irradiation. This procedure offers advantages in terms of higher yields, short reaction times and mild reaction conditions.

The evaluation of Candida albicans biofilms formation on silicone catheter, PVC and glass coated with titanium dioxide nanoparticles by XTT method and ATPase assay

Lots of Candida albicans infections involve in biofilm formation on medical devices. This kind of biofilm can impede antifungal therapy and complicates the treatment of infectious diseases particularly in field of chronic diseases associated with implanted devices. This study has investigated the influence of treating silicone catheter, PVC and glass coated with Titanium dioxide (TiO2) nanoparticles on attachment of C. albicans. In this study TiO2 nanoparticles were synthesized from precursor TiCl4 and characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) which showed TiO2 nanoparticles are 70-100 nm in size. In the simplest model of biofilms formation, C. albicans isolates (ATCC10231) and (ATCC 76615) were grown on the surface of small disks of catheter, PVC and glass in a flat-bottomed 12-well plates and evaluated biofilm formation using ATP bioluminescence and tetrazolium salt (XTT) reduction assays. In addition, morphology of C. albicans biofilms after 48 h incubation was observed by SEM. Results indicated that there is a statistical difference between mean of coated samples especially catheter and glass before and after TiO2 nanoparticles coating (p<0.05). In SEM analysis, C. albicans biofilm was more aggregated on the surface of glass and catheter than PVC and control groups and after treatment by these nanoparticles, catheter and glass both showed most significant decrease of C. albicans attachment in comparison to the control groups (Fig. 4, Ref. 23).

Immunization against leishmaniasis by PLGA nanospheres loaded with an experimental autoclaved Leishmania major (ALM) and Quillaja saponins

Immune responses against the Leishmania antigens are not sufficient to protect against a leishmania challenge. Therefore these antigens need to be potentiated by various adjuvants and delivery systems. In this study, Poly (d,l-lactide-co-glycolide (PLGA) nanospheres as antigen delivery system and Quillaja saponins (QS) as immunoadjuvant have been used to enhance the immune response against autoclaved Leishmania major (ALM). PLGA nanospheres were prepared by a double-emulsion (W/O/W) technique. Particulate characteristics were studied by scanning electron microscopy and particle size analysis. Mean diameter for nanospheres loaded with ALM+QS was 294 ± 106 nm. BALB/c mice were immunized three times in 3-weeks intervals using ALM plus QS loaded nanospheres [(ALM+QS)PLGA], ALM encapsulated with PLGA nanospheres [(ALM)PLGA], (ALM)PLGA + QS, ALM + QS, ALM alone or PBS. The intensity of infection induced by L. major challenge was assessed by measuring size of footpad swelling. The strongest protection, showed by significantly (P < 0.05) smaller footpad, were observed in mice immunized with (ALM)PLGA. The (ALM+QS)PLGA group showed the least protection and highest swelling, while the (ALM)PLGA+QS, ALM+QS and ALM showed an intermediate protection with no significant difference. The mice immunized with ALM and ALM+QS showed the highest IgG2a/IgG1 ratio (P < 0.01), followed by (ALM)PLGA+QS. The highest IFN-γ and lowest IL-4 production was seen in (ALM)PLGA+QS, ALM+QS groups. The highest parasite burden was observed in (ALM)PLGA+QS and (ALM+QS)PLGA groups. It is concluded that PLGA nanospheres as a vaccine delivery system could increase the protective immune responses, but QS adjuvant has a reverse effect on protective immune responses and the least protective responses were seen in the presence of this adjuvant.

Augmentation of shoulder contour using a calf implant

Sprengel deformity is a rare orthopedic condition that is associated with functional and cosmetic impairment. Results of orthopedic procedures are usually inconsistent and cosmetic results are far from satisfactory in these patients. A silicone-gel-filled calf prosthesis was used to correct the shoulder contour in a patient with Sprengel deformity. Cosmetically the deformity can be restored by using a calf implant for patients in whom orthopedic procedures are not likely to yield a satisfactory outcome.

Identifying the management development needs of senior executives in Iran's teaching hospitals

This research paper reports the findings of the first comprehensive survey of senior executives in Iran's teaching hospitals. It is based on an analysis identifying the continuing professional development (CPD) needs of the total population of the two senior levels of teaching hospitals management-presidents of physician-managers and administrative-managers. Four key areas of management knowledge were selected as the focus of the need identification: operational; financial; human resource; and organization change. The findings reveal a pent up demand for introductory level, formal knowledge in all four areas of management theory, to complement and extend the practical experience they have acquired in managing the complex environment of teaching hospitals. The paper goes on to propose a curriculum design and overall framework of provision to meet these genuinely felt CPD needs.

Fate of endoleaks after endoluminal repair of abdominal aortic aneurysms with the EVT device

OBJECTIVE

we aim to describe our medium-term follow-up of 20 patients with an endoleak following repair of their abdominal aortic aneurysms (AAA) using the Endovascular Technologies (EVT) device.

DESIGN

the experience of one centre in a prospective multicentre phase II trial.

MATERIALS AND METHODS

55 patients with an endovascular repair of their AAA and at least 6 months>> follow-up were reviewed. Intraoperative angiograms, next day duplex scans and computed tomography (CT) images were used to detect endoleaks. Follow-up with CT and duplex was performed at 3, 6, 12 and 24 months. Persistent endoleaks at 6 months were evaluated by angiography and treated by endovascular coiling.

RESULTS

there were three immediate conversions to open procedures. Twenty of 52 (38%) patients had an endoleak identified initially. One patient died from a myocardial infarction and three were not evident any longer by discharge CT. Sixteen endoleaks (31%) were present at discharge. Nine resolved spontaneously by 3-6 months and seven were still persistent at 6 months (14%). Six patients underwent coiling of their leak, all with successful radiographic seal after 1-3 sessions.

CONCLUSIONS

endoleaks are frequent after endovascular AAA repair, but the majority close spontaneously. Coiling of the leaks and radiographic seal can be achieved in all cases still persistent at 6 months. Whether this method is clinically effective awaits further follow-up.

Monokine-induced neutrophil chemotactic factor gene expression in human fibroblasts

Although fibroblasts are important in providing a structural framework for most tissues, they also appear to be active participants in the inflammatory process via the production of specific mediators. The production of inflammatory mediators by fibroblasts is especially important in relation to their strategic location within connective tissue as they may act as a cellular communication bridge between the interstitium and vasculature. In this paper, we demonstrate that fibroblasts may participate in these inflammatory reactions by the production of a neutrophil chemotactic factor (NCF) with characteristics similar to a recently isolated and cloned monocyte-derived NCF. Either tumor necrosis factor-alpha-, interleukin-1 alpha-, or interleukin-1 beta-stimulated fibroblasts showed both a time- and dose-dependent increase in steady-state levels of NCF mRNA and secretion of chemotactic activity. In contrast, lipopolysaccharide and interleukin-6 failed to induce fibroblast-derived NCF. The expression of fibroblast-derived NCF mRNA was first detectable by 30 min poststimulation, whereas chemotactic activity was significantly observed 3-4 h postchallenge. Heat-inactivated monokine (100 degrees C) failed to induce NCF mRNA expression, suggesting that only the active proteins are capable of inducing NCF. Gel filtration analysis using high pressure liquid chromatography indicated peak chemotactic activity with an approximate molecular mass of 8000 daltons. This peak of NCF activity was found to be relatively stable to both heat and trypsin inactivation. Specificity of the fibroblast-derived neutrophil chemotactic activity was demonstrated with inhibition of chemotaxis by the addition of neutralizing antibody directed against recombinant human neutrophil chemotactic factor. These data provide evidence that monokine-treated fibroblasts can synthesize a potent chemotactic agent with molecular and physicochemical characteristics similar to monocyte-derived NCF and that this factor may contribute to neutrophil-mediated disease processes.

In vivo dynamics of murine tumor necrosis factor-alpha gene expression. Kinetics of dexamethasone-induced suppression

Tumor necrosis factor-alpha (TNF) has been implicated as an important, proximal mediator of many of the pathophysiologic effects observed during septic shock. In vitro studies have demonstrated that the glucocorticoid dexamethasone (Dex) will suppress the production of TNF; yet, clinical studies have shown that glucocorticoids are not protective in septic shock. In this paper we described the in vivo effects of lipopolysaccharide (LPS) on the kinetics of local and systemic TNF production, the time dependent expression of TNF mRNA, and the suppression of both TNF mRNA and bioactive protein using a defined treatment protocol of Dex. Peritoneal macrophages were elicited by CBA/J mice in the injection of complete Freunds adjuvant and the mice challenged with an intraperitoneal injection of LPS 2 weeks later. Kinetic studies showed that the peak of TNF production occurred 1 hour post LPS injection and reached a maximum of 775 units/ml within the ascites and 26 units/ml within the plasma. Northern blot analysis of mRNA extracted from peritoneal cells showed a peak of mRNA 30 minutes post LPS challenge. Dose-response studies disclosed that 10 micrograms of LPS/mouse produced maximal TNF within the ascites fluid, and half-maximal stimulation occurred at 70 ng LPS/mouse. Mice treated with Dex in vivo before LPS challenge showed a dramatic reduction in TNF production within both the ascites and plasma, and Northern blot analysis showed a corresponding reduction in the TNF specific mRNA. Further studies revealed that mice treated with 4 mg/kg of Dex intraperitoneally 4 hours before, or at the time of LPS challenge, had dramatic reductions in TNF levels within both the ascites and plasma. However, delaying the treatment only 20 minutes after LPS injection failed to significantly reduce TNF in either compartment. These data may provide a rationale why glucocorticoids are not clinically efficacious in the treatment of septic shock, since there is rapid upregulation of LPS-induced TNF gene expression. By the time patients develop clinical signs and symptoms of septic shock there are already preformed, circulating levels of TNF.