Method to characterize inorganic particulates in lung tissue biopsies using field emission scanning electron microscopy.

Humans accumulate large numbers of inorganic particles in their lungs over a lifetime. Whether this causes or contributes to debilitating disease over a normal lifespan depends on the type and concentration of the particles. We developed and tested a protocol for in situ characterization of the types and distribution of inorganic particles in biopsied lung tissue from three human groups using field emission scanning electron microscopy (FE-SEM) combined with energy dispersive spectroscopy (EDS). Many distinct particle types were recognized among the 13 000 particles analyzed. Silica, feldspars, clays, titanium dioxides, iron oxides and phosphates were the most common constituents in all samples. Particles were classified into three general groups: endogenous, which form naturally in the body; exogenic particles, natural earth materials; and anthropogenic particles, attributed to industrial sources. These in situ results were compared with those using conventional sodium hypochlorite tissue digestion and particle filtration. With the exception of clays and phosphates, the relative abundances of most common particle types were similar in both approaches. Nonetheless, the digestion/filtration method was determined to alter the texture and relative abundances of some particle types. SEM/EDS analysis of digestion filters could be automated in contrast to the more time intensive in situ analyses.

Axonal transport of AAV9 in nonhuman primate brain.

A pilot study in nonhuman primates was conducted, in which two Rhesus macaques received bilateral parenchymal infusions of adeno-associated virus serotype 9 encoding green fluorescent protein (AAV9-GFP) into each putamen. The post-surgical in-life was restricted to 3 weeks in order to minimize immunotoxicity expected to arise from expression of GFP in antigen-presenting cells. Three main findings emerged from this work. First, the volume over which AAV9 expression was distributed (Ve) was substantially greater than the volume of distribution of MRI signal (Vd). This stands in contrast with Ve/Vd ratio of rAAV2, which is lower under similar conditions. Second, post-mortem analysis revealed expression of GFP in thalamic and cortical neurons as well as dopaminergic neurons projecting from substantia nigra pars compacta, indicating retrograde transport of AAV9. However, fibers in the substantia nigra pars reticulata, a region that receives projections from putamen, also stained for GFP, indicating anterograde transport of AAV9 as well. Finally, one hemisphere received a 10-fold lower dose of vector compared with the contralateral hemisphere (1.5 × 10(13) vg ml(-1)) and we observed a much stronger dose effect on anterograde-linked than on retrograde-linked structures. These data suggest that AAV9 can be axonally transported bi-directionally in the primate brain. This has obvious implications to the clinical developing of therapies for neurological disorders like Huntington's or Alzheimer's diseases.

Evaluation of the Pulmonary Toxicity of Ambient Particulate Matter From Camp Victory, Iraq.

Anecdotal reports in the press and epidemiological studies suggest that deployment to Iraq and Afghanistan may be associated with respiratory diseases and symptoms in U.S. military personnel and veterans. Exposures during military operations were complex, but virtually all service members were exposed to high levels of respirable, geogenic dust. Inhalation of other dusts has been shown to be associated with adverse health effects, but the pulmonary toxicity of ambient dust from Iraq has not been previously studied. The relative toxicity of Camp Victory dust was evaluated by comparing it to particulate matter from northern Kuwait, a standard U.S. urban dust, and crystalline silica using a single intratracheal instillation in rats. Lung histology, protein levels, and cell counts were evaluated in the bronchoalveolar lavage fluid 1-150 d later. The Iraq dust provoked an early significant, acute inflammatory response. However, the level of inflammation in response to the Iraq dust, U.S. urban dust, and Kuwait dust rapidly declined and was nearly at control levels by the end of the study At later times, animals exposed to the Iraq, U.S. urban, or Kuwait dusts showed increased small airway remodeling and emphysema compared to silica-exposed and control animals without evidence of fibrosis or premalignant changes. The severity and persistence of pulmonary toxicity of these three dusts from the Middle East resemble those of a U.S. urban dust and are less than those of silica. Therefore, Iraq dust exposure is not highly toxic, but similar to other poorly soluble low-toxicity dusts.

Traffic-related air pollution, chronic stress, and changes in exhaled nitric oxide and lung function among a panel of children with asthma living in an underresourced community.

We examined associations between short-term exposure to traffic-related air pollutants (TRAP) and airway inflammation and lung function in children with asthma, and whether these associations are modified by chronic psychological stress. Residents of underresourced port-adjacent communities in New Jersey were concerned about the cumulative impacts of exposure to TRAP, particularly diesel-engine truck emissions, and stress on exacerbation of asthma among children. Children with asthma aged 9-14 (n = 35) were recruited from non-smoking households. We measured each participant's (1) continuous personal exposure to black carbon (BC, a surrogate of TRAP) at 1-min intervals, (2) 24-h integrated personal exposure to nitrogen dioxide (NO2), (3) daily fractional exhaled nitric oxide (FeNO), and (4) lung function for up to 30 consecutive days. Personal BC was recorded by micro-aethalometers. We measured daily FeNO using the NIOX MINO, forced expiratory volume in one second (FEV1), and forced vital capacity (FVC) using Easy One Frontline spirometers. Chronic stress was measured with the UCLA Life Stress Interview for Children. The association was examined using linear mixed-effect models. In the fully adjusted model, an interquartile range (IQR) increase in BC at lag 0-6 h before the FeNO measurement was associated with 8 % (95 % CI: 3 % - 12 %) increase in FeNO, whereas an IQR increase in BC at lag 7-12 h and lag 0-24 h were associated with 6 % (95 % CI: 2 % - 11 %) and 7 % (2 % - 12 %) FeNO increases, respectively. There were no significant lung function changes per IQR increase in BC. No interactions were observed between chronic stress and BC on FeNO. Chronic stress was negatively associated with individual average FeNO levels. Our findings suggest that higher levels of BC exposure within the prior 24 h increased airway inflammation levels in children with asthma, with the strongest effect observed within the first 6 h.

External quality assessment of human neutrophil antigen (HNA)-specific antibody detection and HNA genotyping from 2000 to 2012.

Since 2000, Quality Assurance (QA) exercises for the detection and identification of granulocyte antibodies and DNA typing for human neutrophil antigens (HNA) have been distributed within the International Granulocyte Immunobiology Workshops, which are linked to International Society of Blood Transfusion. The exercises were standardised at the outset to enable laboratory performance to be monitored. Between 2000 and 2012, nine exercises were distributed to 20 laboratories. Overall, 45 examples of 42 unique samples containing defined granulocyte reactive antibodies were distributed for serological analysis together with 20 samples for HNA genotyping. The level of satisfactory serological performance was initially set at 50% and later increased to 70%, while the 'cut-off' for HNA genotyping was set at 100% after 2008. Failure to achieve the minimum score in the QA exercises in consecutive years resulted in temporary exclusion. In 2000, the 15 participating laboratories had a mean score of 56.1% for serological analysis and 13 laboratories attempted HNA-1a and -1b genotyping, while 11 attempted HNA-1c typing. Steady improvements in proficiency for serological testing and HNA typing occurred in subsequent exercises. In 2012, the mean score for serology was 88.5% and 12/13 laboratories scored 100% for HNA-1a, -1b, -1c, -3a, -3b, -4a, -4bw, -5a and -5bw genotyping. These QA exercises have provided an invaluable tool to monitor and improve the standard of granulocyte immunology investigations for participating laboratories, thereby enhancing performance for both clinical investigations and donor screening programmes to reduce the incidence of TRALI.

Mass spectrometry and informatics: distribution of molecules in the PubChem database and general requirements for mass accuracy in surface analysis.

Mass spectrometry is a powerful tool for the analysis and identification of substances across a broad range of technologies from proteomics and metabolomics through to surface analysis methods used for nanotechnology. A major challenge has been the development of automated methods to identify substances from the mass spectra. Public chemical databases have grown over 2 orders of magnitude in size over the past few years and have become a powerful tool in informatics approaches for identification. We analyze the popular PubChem database in terms of the population of substances with mass when resolved with typical mass spectrometer mass accuracies. We also characterize the average molecule in terms of the mass excess from nominal mass and the modal mass. It is shown, in agreement with other studies, that for the identification of unknowns a mass accuracy of around 1 ppm is required together with additional filtering using isotope patterns. This information is an essential part of a framework being developed for experimental library-free interpretation of complex molecule spectra in secondary ion mass spectrometry.

T-lymphocytes regulate genetically determined airway hyperresponsiveness in mice.

Airway hyperresponsiveness (AHR) is a hallmark of asthma and a heritable polygenic trait in the mouse. In the mouse, candidate gene products of hematopoietic origin implicated in asthma mapped to the regions of the previously defined quantitative trait loci. Since hematopoietic cells have been implicated in the pathogenesis of asthma, we evaluated the role of hematopoietic cells in general and T cells specifically in the genetic modulation of native airway responsiveness in mice. Here, with the use of bone marrow transplantation, anti-T-cell monoclonal antibody treatment and T-cell transfer, we demonstrate that intrinsic non-atopic AHR is mediated by T lymphocytes. Our data support the novel concept that, in the absence of identified environmental influences, T cells enhance genetically determined airway responsiveness.

Investigative strategies for fish bone foreign bodies during the coronavirus disease 2019 pandemic: an analysis of ENT UK guidelines.

BACKGROUND: By nature of their specialty, otolaryngologists are disproportionately exposed to coronavirus disease 2019 through aerosol-generating procedures and close proximity to the oropharynx during examination. METHODS: Our single-centre, retrospective study analysed the pertinence of guidelines produced by ENT UK to improve the investigation and management of suspected upper aerodigestive fish bone foreign bodies during the coronavirus disease 2019 pandemic. RESULTS: Our results demonstrated 43.3 per cent (n = 13) low-risk cases and 56.7 per cent (n = 17) moderate-risk cases. Nine fish bones (two low risk, seven moderate risk) were found; none of these were confirmed with X-ray and three (moderate risk) required nasoendoscopy for diagnosis. One patient required rigid pharyngoscopy. CONCLUSION: This study confirms that soft tissue neck X-ray and flexible nasoendoscopy are unnecessary in low-risk cases; however, early nasoendoscopy in higher suspicion cases is appropriate. Recommendations are made about the long-term sustainability of these guidelines, and additional measures are encouraged that relate to repeat attendances and varying prevalence of coronavirus disease 2019 in the hospital catchment area.

Customised vestibular rehabilitation with the addition of virtual reality based therapy in the management of persistent postural-perceptual dizziness.

OBJECTIVE: Visual-vestibular mismatch patients experience persistent postural and perceptual dizziness. Previous studies have shown the benefit of vestibular rehabilitation for visual desensitisation using gaze stabilisation exercises and optokinetic stimulation. This study assessed the benefit of customised vestibular rehabilitation with visual desensitisation and virtual reality based therapy rehabilitation in the management of patients with persistent postural-perceptual dizziness. METHODS: This retrospective study included 100 patients with Situational Characteristic Questionnaire scores of more than 0.9. All patients received virtual reality based therapy along with usual vestibular rehabilitation using gaze stabilisation exercises with a plain background followed by graded visual stimulation and optokinetic digital video disc stimulation. Patients' symptoms were assessed before and after vestibular rehabilitation using the Situational Characteristic Questionnaire, Generalised Anxiety Disorder Assessment-7, Nijmegen Questionnaire and Dizziness Handicap Inventory. RESULTS: There were statistically significant improvements in Situational Characteristic Questionnaire scores, Nijmegen Questionnaire scores and Dizziness Handicap Inventory total score. However, there was a statistically insignificant difference in Generalised Anxiety Disorder Assessment-7 scores. There was a significant positive correlation between post-rehabilitation Situational Characteristic Questionnaire scores and other questionnaire results. CONCLUSION: Incorporating virtual reality based therapy with customised vestibular rehabilitation exercises results in significant improvement in persistent postural-perceptual dizziness related symptoms.

Regenerative medicine for end-stage fibrosis and tissue loss in the upper aerodigestive tract: a twenty-first century review.

OBJECTIVE: This review assesses regenerative medicine of the upper aerodigestive tract during the first two decades of the twenty-first century, focusing on end-stage fibrosis and tissue loss in the upper airways, salivary system, oropharynx and tongue. METHOD: PubMed, Embase, Google Scholar, Cochrane Library, Medline and clinicaltrials.org were searched from 2000 to 2019. The keywords used were: bioengineering, regenerative medicine, tissue engineering, cell therapy, regenerative surgery, upper aerodigestive tract, pharynx, oropharynx, larynx, trachea, vocal cord, tongue and salivary glands. Original studies were subcategorised by anatomical region. Original human reports were further analysed. Articles on periodontology, ear, nose and maxillofacial disorders, and cancer immunotherapy were excluded. RESULTS: Of 716 relevant publications, 471 were original studies. There were 18 human studies included, within which 8 reported airway replacements, 5 concerned vocal fold regeneration and 3 concerned salivary gland regeneration. Techniques included cell transplantation, injection of biofactors, bioscaffolding and bioengineered laryngeal structures. CONCLUSION: Moderate experimental success was identified in the restoration of upper airway, vocal fold and salivary gland function. This review suggests that a shift in regenerative medicine research focus is required toward pathology with a higher disease burden.

Marked antiinflammatory effects of decentralization of the superior cervical ganglia.

Intravenous challenge with parasite antigens in Nippostrongylus brasiliensis-sensitized rats resulted in anaphylactic shock and, in some animals, death. Surviving animals showed significant drop in mean arterial blood pressure, cardiac output, and blood flow to the trachea, bronchioles, and mesentery. After anaphylaxis, changes in the cellular and protein composition in bronchoalveolar lavage fluids (BALF) were assessed. 8 h after antigen challenge, there was significant influx of inflammatory cells and an increase in the levels of histamine and serum-derived immunoglobulins (IgG and IgM) in BALF. Chemotactic activity for neutrophils was also present in BALF. Once we established this anaphylaxis-induced model of pulmonary inflammation, we sought to determine whether or not the superior cervical ganglia (SCG) modulate this inflammation. We performed bilateral superior cervical ganglionectomy or decentralization of the SCG. Our results show that decentralization significantly reduced mortality (by 68%) after anaphylaxis. Furthermore, the increases in levels of serum-derived proteins, histamine, and influx of cells (especially neutrophils) observed in BALF after anaphylaxis were attenuated by both decentralization and ganglionectomy. By contrast, hemodynamic parameters in the respiratory tract and the presence of neutrophil chemotactic activity in BALF were not influenced by decentralization. Thus, the severity of pulmonary inflammation initiated by systemic anaphylaxis is depressed by bilateral ganglionectomy or decentralization of SCG.

Signal transducer and activator of transcription 6 controls chemokine production and T helper cell type 2 cell trafficking in allergic pulmonary inflammation.

Antigen-specific CD4 T helper type 2 (Th2) cells play a pivotal role in the induction of allergic asthma, but the mechanisms regulating their recruitment into the airways are unknown. Signal transducer and activator of transcription factor (Stat)6 is a transcription factor essential for Th2 cell differentiation. Here we show that Stat6 also controls Th2 cell recruitment and effector function in allergic inflammation in vivo. To isolate the role of Stat6 in regulating Th2 cell trafficking and effector function from its role in Th2 cell differentiation, we used a murine model of asthma in which in vitro-differentiated Stat6(+/+) antigen-specific Th2 cells were adoptively transferred into naive Stat6(-/-) and Stat6(+/+) mice followed by aerosol antigen challenge. We found that all of the features of asthma, including Th2 cell accumulation, Th2 and eosinophil-active chemokine production, and airway eosinophilia, mucus production, and hyperresponsiveness seen in Stat6(+/+) mice, were dramatically absent in Stat6(-/)- mice that received Stat6(+/)+ antigen-specific Th2 cells. Our findings establish Stat6 as essential for Th2 cell trafficking and effector function and suggest that interruption of Stat6 signaling in resident cells of the lung is a novel approach to asthma therapy.

Increased myoepithelial cells of bronchial submucosal glands in fatal asthma.

BACKGROUND: Fatal asthma is characterised by enlargement of bronchial mucous glands and tenacious plugs of mucus in the airway lumen. Myoepithelial cells, located within the mucous glands, contain contractile proteins which provide structural support to mucous cells and actively facilitate glandular secretion. OBJECTIVES: To determine if myoepithelial cells are increased in the bronchial submucosal glands of patients with fatal asthma. METHODS: Autopsied lungs from 12 patients with fatal asthma (FA), 12 patients with asthma dying of non-respiratory causes (NFA) and 12 non-asthma control cases (NAC) were obtained through the Prairie Provinces Asthma Study. Transverse sections of segmental bronchi from three lobes were stained for mucus and smooth muscle actin and the area fractions of mucous plugs, mucous glands and myoepithelial cells determined by point counting. The fine structure of the myoepithelial cells was examined by electron microscopy. RESULTS: FA was characterised by significant increases in mucous gland (p = 0.003), mucous plug (p = 0.004) and myoepithelial cell areas (p = 0.017) compared with NAC. When the ratio of myoepithelial cell area to total gland area was examined, there was a disproportionate and significant increase in FA compared with NAC (p = 0.014). Electron microscopy of FA cases revealed hypertrophy of the myoepithelial cells with increased intracellular myofilaments. The NFA group showed changes in these features that were intermediate between the FA and NAC groups but the differences were not significant. CONCLUSIONS: Bronchial mucous glands and mucous gland myoepithelial cell smooth muscle actin are increased in fatal asthma and may contribute to asphyxia due to mucous plugging.

The effect of electrospray solvent composition on desorption electrospray ionisation (DESI) efficiency and spatial resolution.

In desorption electrospray ionisation (DESI) the interaction between the electrospray and the surface is key to two important analytical parameters, the spatial resolution and the sensitivity. We evaluate the effect of the electrospray solvent type, organic solvent fraction with water, analyte solubility and substrate wettability on DESI erosion diameter and material transferral into useful ion signal. To do this five amino acids, glycine, alanine, valine, leucine and phenylalanine are prepared as thin films on three substrates, UV/ozone treated glass, glass and polytetrafluoroethylene (PTFE). Four different solvents, acetonitrile (ACN), methanol (MeOH), ethanol (EtOH) and propan-2-ol (IPA), are used with organic solvent fractions with water varying from 0.1 to 1. These model systems allow the solubility or wettability to be kept constant as other parameters are varied. Additionally, comparison with electrospray ionisation (ESI) allows effects of ionisation efficiency to be determined. It is shown that the DESI efficiency is linearly dependent on the solubility (for these materials at least) and for analytes with solubilities below 1.5 g kg(-1), additional strategies may be required for DESI to be effective. We show that the DESI erosion diameter improves linearly with organic solvent fraction, with an organic solvent fraction of 0.9 instead of 0.5 leading to a 2 fold improvement. Furthermore, this leads to a 35 fold increase in DESI efficiency, defined as the molecular ion yield per unit area. It is shown that these improvements correlate with smaller droplet sizes rather than surface wetting or ionisation.

Personality disorders in offenders with intellectual disability: a comparison of clinical, forensic and outcome variables and implications for service provision.

AIM: To establish any differences between patients with and without a diagnosis of personality disorders, being treated in a secure inpatient service for offenders with intellectual disability (ID) in the UK. METHOD: A cohort study involving a selected population of people with ID and offending behaviours. Results The study included a total of 138 patients, treated over a 6 year period - 77 with a dissocial or emotionally unstable personality disorder and 61 without. Women were more likely to be in the personality disorder group. Both groups had high prevalence of abuse with no significant differences. Depressive disorders and substance abuse were more common in the personality disorder group, while epilepsy and autistic spectrum disorders were more common in the non-personality disorder group. Rather than differences, what was more striking was the rate and range of these comorbidities across both groups. Although past histories of violence and institutional aggression were no different, compulsory detention under criminal sections and restriction orders were more common in the personality disorder group. There were no differences in treatment outcomes. CONCLUSIONS: Although about half of patients detained in secure units for offenders with ID have a personality disorder, there were more similarities than differences between this group and the rest. While good treatment outcomes supported the case for specialised secure treatment units for people with ID, the case for establishing a more specialised ID-personality disorder unit was less convincing. There is also a need to explore whether there are alternative diagnostic models that can delineate better the group with personality difficulties in this population.

Analysis of the interface and its position in C60(n+) secondary ion mass spectrometry depth profiling.

C60(n+) ions have been shown to be extremely successful for SIMS depth profiling of a wide range of organic materials, causing significantly less degradation of the molecular information than more traditional primary ions. This work focuses on examining the definition of the interface in a C60(n+) SIMS depth profile for an organic overlayer on a wafer substrate. First it investigates the optimum method to define the organic/inorganic interface position. Variations of up to 8 nm in the interface position can arise from different definitions of the interface position in the samples investigated here. Second, it looks into the reasons behind large interfacial widths, i.e., poor depth resolution, seen in C60(n+) depth profiling. This work confirms that, for Irganox 1010 deposited on a wafer, the depth resolution at the Irganox 1010/substrate interface is directly correlated to the roughening of material. C60n+

Developing repeatable measurements for reliable analysis of molecules at surfaces using desorption electrospray ionization.

Desorption electrospray ionization (DESI) is a powerful ambient ionization technique that can provide high-sensitivity mass spectrometry information directly from surfaces at ambient pressure. Although a growing amount of research has been devoted to exploring different applications, there are few studies investigating the basic parameters and underpinning metrology. An understanding of these is crucial to develop DESI as the robust and reliable technique required for significant uptake by industry. In this work, we begin with a systematic study of the parameters affecting the repeatability, sensitivity, and rate of consumption of material with DESI. To do this we have developed a model sample consisting of a thin uniform film of controlled thickness of Rhodamine B on glass. This model sample allowed assessment of optimal sensitivity and spot shape under different conditions. In addition, it allowed us to study the surface in more detail to understand why and how each parameter affects these. Using the model sample to optimize the instrument parameters for DESI led to an absolute intensity repeatability of better than 15%, achieved over a period of 1 day. This model sample provides valuable insight into the electrospray-sample interaction and the desorption mechanism. Confocal microscopy of areas analyzed by DESI allow droplet distribution, material utilization, and spot size to be determined. Studying surface erosion also gives the erosion rate of material, analogous to the sputtering yield in secondary ion mass spectrometry. The results of the study provide a clear description that explains the differences observed with changing electrospray parameters allowing optimization of the technique, for both spatial resolution and sensitivity.

Airway smooth muscle thickness in asthma is related to severity but not duration of asthma.

Asthma is characterised by an increased airway smooth muscle (ASM) area (ASM(area)) within the airway wall. The present study examined the relationship of factors including severity and duration of asthma to ASM(area). The perimeter of the basement membrane (PBM) and ASM(area) were measured on transverse sections of large and small airways from post mortem cases of fatal (n = 107) and nonfatal asthma (n = 37) and from control subjects (n = 69). The thickness of ASM (ASM(area)/PBM) was compared between asthma groups using multivariate linear regression. When all airways were considered together, ASM(area)/PBM (in millimetres) was increased in nonfatal (median 0.04; interquartile range 0.013-0.051; p = 0.034) and fatal cases of asthma (0.048; 0.025-0.078; p<0.001) compared with controls (0.036; 0.024-0.042). Compared with cases of nonfatal asthma, ASM(area)/PBM was greater in cases of fatal asthma in large (p<0.001) and medium (p<0.001), but not small, airways. ASM(area)/PBM was not related to duration of asthma, age of onset of asthma, sex or smoking. No effect due to study centre, other than that due to sampling strategy, was found. The thickness of the ASM layer is increased in asthma and is related to the severity of asthma but not its duration.

Reconstitution of Rh (D) antigen activity from human erythrocyte membranes solubilized by deoxycholate.

Proteins were selectively solubilized from human erythrocyte membranes with deoxycholate. After ultracentrifugation and preliminary fractionation procedures, the detergent was removed from the soluble membranes by Bio-Beads SM-2 and dialysis against 5 millimolar magnesium chloride. Reaggregation took place with the apparent formation of vesicles which showed serologically specific Rh antigen activity.

The mechanics of esophageal muscle contraction. Evidence of an inotropic effect of gastrin.

To compare the mechanical properties of lower esophageal sphincter (LES) and esophageal circular smooth muscle, force-velocity determinations were made under various physiological conditions. Isotonic and isometric recordings of opossum circular muscle were used to obtain the velocity of shortening and force, respectively, during alterations in: (a) initial muscle length (preload), (b) afterload, (c) calcium concentration, and (d) gastrin I. Muscle contraction was elicited to the neurogenic response at the termination of electrical stimulation. A change in preload (muscle length) altered the peak force (Po) developed during an afterloaded contraction, but had only a minor effect on the maximum velocity of shortening (V max). At the length of optimal tension development, Lo, (preload, 1.5 g), the LES muscle had a V max of 6.1+/-0.2 mm/s and a Po of 17.7+/-0.7 g. The esophageal muscle at its Lo (preload, 2.0 g) had a V max of 6.3+/-0.5 mm/s and a Po of 18.1+/-1.2 g. A decrease in calcium from 2.5 mM to 1.0 mM significantly reduced the V max and Po of all muscle, but an increase in calcium to 5.0 mM increased these parameters only minimally. At a calcium of 1.0 mM, gastrin I increased both V max and Po of all muscle. This inotropic effect of gastrin I occurred at lower concentrations in LES muscle than in muscle from the upper esophagus. The power (force x velocity) and work (force x muscle shortening) of esophageal and LES muscle were calculated from these data. Both the work and power generated during esophageal and LES muscle contraction were determined by: (a) the initial muscle length as produced by the preload, (b) the afterload against which the muscle was contracting, and (c) the contractility of inotropism of the muscle, that is, the force-velocity curve on which the muscle was operating.