"Tan and Crunchy Is Where We Live": An Interpretative Phenomenological Analysis of Caregivers' Perspectives of Pediatric Feeding Disorder in Children With Developmental Disability

PURPOSE

The purpose of this study was to examine caregivers' perceptions of feeding disorders in their young child who also had a co-occurring developmental disability (DD).

METHOD

Using interpretative phenomenological analysis, eight caregivers of children with DD and pediatric feeding disorder (PFD) were interviewed. Interviews were recorded, transcribed, and analyzed for the lived experiences of caregivers. Thematic analysis, member checking, and an audit were completed by three researchers.

RESULTS

Three themes emerged: Parenting Journey, Emotions and Repercussions, and Winging It. Results indicated caregivers struggled to find appropriate professional help, referenced lack of confidence in the professionals designated to help, and were often ambivalent in approach to the PFD. Indications were that parents were frequently retelling past experiences as they presented the narrative of the feeding disorder and, as such, created narratives that became part of their present and the future experiences when feeding their child.

CONCLUSIONS

Implications for speech-language pathologists are considered. Particularly, interventions that go beyond the immediate environmental variables of the feeding or mealtime environment are considered, including the application of this analysis to necessary psychological flexibility for caregivers of children with PFD.

Cardio-Oncology: a medical specialty in constant growth and evolution. the 10-year experience of the first cardio-oncology service in the United Kingdom

Introduction

Survivorship has increased significantly in cancer patients with the advent of novel therapies. However, this improvement has been at the cost of higher rates of cardiotoxicity. Cardiovascular disease has become the main cause of death or cancer therapy interruption in many of these patients. The need for specialist services to deal with these emerging problems has led to global development of many Cardio-Oncology services.

Objectives

To describe how a Cardio-Oncology service has grown and evolved over a 10 year period in response to the constantly changing oncological landscape.

Methods and results

Prospective, single center, study of cancer patients referred to our service from February 2011 to December 2021. 1499 patients were referred to the service. Mean age was 60 years (SD: 15) and 60% were female. CV risk factors including hypertension (32%), dyslipidaemia (12%) and diabetes (6%) were common.

The most frequent primary tumour location was breast (427 patients, 28%), followed by haematological (151, 10%) and gastrointestinal tract (114, 8%). The average number of referrals per month increased 6 fold from 2011, from 3.3 patients per month to 21 patients in 2021. In the last 5 years there was a 10 fold increase in the number of outpatient consultations from 189 consultations in 2016 to 1988 consultations in 2021.

The most frequent reason for referral was pre-treatment assessment (39%), followed by cancer therapy related cardiac dysfunction (CTRCD) (33%) and other acute cancer therapy related CV diseases (CTR-CVDs) (22%). From 2011 to 2017 CTRCD was the main CTR-CVD due to anthracycline and trastuzumab. This ratio changed in 2018 when other CTR-CVDs became the most frequent referral reason following pre-treatment assessment. Patients referred to our service were or had been, mostly under medical therapy alone or in combination with surgery or radiotherapy (1058 patients, 70%), anthracyclines being the predominant treatment (435 patients, 40%). Targeted therapies and immune check point inhibitors became more popular in the last two years (2020–2021). A multivariable logistic regression model was built to assess the relation between the medical treatment and the prevalence of CTRCD vs other CTR-CVDs. Anthracyclines and HER2 therapy are independently associated with a higher prevalence of CTRCD while tyrosine kinase inhibitors and immune checkpoint inhibitors increase the risk of other CTR-CVDs e.g. hypertension, arrhythmias and myocarditis.

Conclusions

Cardio-Oncology has rapidly evolved from its origin as a subspecialty of heart failure medicine, to a diverse medical specialty that encompasses many different domains of cardiology. Future cardio-oncology services should reflect this and be dynamic, collaborating with cardiac sub-specialities as necessary. Provision of cardio-oncology services requires a considerable knowledge and understanding of the ever growing and changing oncology therapies.

Funding Acknowledgement

Type of funding sources: None.

The roles of a pediatric pulmonologist during the COVID-19 pandemic

Pediatric pulmonologists have been involved in the care of adult COVID-19 patients in a variety of ways, particularly in areas with a high concentration of cases. This invited commentary is a series of questions to Dr Mikhail Kazachkov, a pediatric pulmonologist at New York University, about his experiences to date in a major COVID-19 "hotspot" and his thoughts about how other pediatric pulmonologists facing this situation can best support their colleagues.

Enhancing the Seeking Safety group intervention with trauma-sensitive yoga practice: A program evaluation

BACKGROUND AND PURPOSE

The purpose of this article is to report the results of a qualitative Utilization Focused Program Evaluation on the integration of the Seeking Safety manualized group counseling intervention with Trauma-Sensitive (TS) yoga practice at a community mental health agency. To date, there has been no evaluation of Seeking Safety and TS yoga as complementary therapies.

METHOD AND MATERIALS

Qualitative data were generated from key informant interviews and focus groups, then coded and analyzed for theme and content.

RESULTS

Analysis of data indicate that, in this specific setting, the combination of Seeking Safety and TS Yoga was perceived by clients and clinicians as an effective complementary intervention strategy.

CONCLUSION

The results of this qualitative evaluation are specific to the agency utilizing the interventions. By integrating Seeking Safety with TS yoga many of the inherent weaknesses of the two individual approaches were moderated.

Pulmonary vascular mechanical consequences of ischemic heart failure and implications for right ventricular function

Left heart failure (LHF) is the most common cause of pulmonary hypertension, which confers an increase in morbidity and mortality in this context. Pulmonary vascular resistance has prognostic value in LHF, but otherwise the mechanical consequences of LHF for the pulmonary vasculature and right ventricle (RV) remain unknown. We sought to investigate mechanical mechanisms of pulmonary vascular and RV dysfunction in a rodent model of LHF to address the knowledge gaps in understanding disease pathophysiology. LHF was created using a left anterior descending artery ligation to cause myocardial infarction (MI) in mice. Sham animals underwent thoracotomy alone. Echocardiography demonstrated increased left ventricle (LV) volumes and decreased ejection fraction at 4 wk post-MI that did not normalize by 12 wk post-MI. Elevation of LV diastolic pressure and RV systolic pressure at 12 wk post-MI demonstrated pulmonary hypertension (PH) due to LHF. There was increased pulmonary arterial elastance and pulmonary vascular resistance associated with perivascular fibrosis without other remodeling. There was also RV contractile dysfunction with a 35% decrease in RV end-systolic elastance and 66% decrease in ventricular-vascular coupling. In this model of PH due to LHF with reduced ejection fraction, pulmonary fibrosis contributes to increased RV afterload, and loss of RV contractility contributes to RV dysfunction. These are key pathologic features of human PH secondary to LHF. In the future, novel therapeutic strategies aimed at preventing pulmonary vascular mechanical changes and RV dysfunction in the context of LHF can be tested using this model. NEW & NOTEWORTHY In this study, we investigate the mechanical consequences of left heart failure with reduced ejection fraction for the pulmonary vasculature and right ventricle. Using comprehensive functional analyses of the cardiopulmonary system in vivo and ex vivo, we demonstrate that pulmonary fibrosis contributes to increased RV afterload and loss of RV contractility contributes to RV dysfunction. Thus this model recapitulates key pathologic features of human pulmonary hypertension-left heart failure and offers a robust platform for future investigations.

Career Development of Sexual Minority Men Living With HIV

HIV is a diagnosis that disproportionally affects sexual minority (e.g., gay, bisexual, and queer) men living in the United States. Expansive treatment options have allowed those living with HIV to live longer life spans, indicating that sexual minority men living with HIV are remaining engaged in the workforce longer. Yet, there remains a dearth of literature exploring the career trajectories of this specific population. This qualitative study aimed to understand what factors keep sexual minority men ( N = 10) living with HIV actively engaged in the workforce. Through in-depth individual interviews, a central category of psychosocial motility was constructed. Three subsequent categories were also constructed: affirmative support systems, intrinsic and extrinsic incentives, and intrapersonal endowments. Findings are discussed, along with implications for practice, limitations, and future research.

A comparison of HFrEF vs HFpEF's clinical workload and cost in the first year following hospitalization and enrollment in a disease management program

BACKGROUND

Admission with heart failure (HF) is a milestone in the progression of the disease, often resulting in higher intensity medical care and ensuing readmissions. Whilst there is evidence supporting enrolling patients in a heart failure disease management program (HF-DMP), not all reported HF-DMPs have systematically enrolled patients with HF with preserved ejection fraction (HFpEF) and there is a scarcity of literature differentiating costs based on HF-phenotype.

METHODS

1292 consenting, consecutive patients admitted with a primary diagnosis of HF were enrolled in a hospital based HF-DMP and categorized as HFpEF (EF≥45%) or HFrEF (EF<45%). Hospitalizations, primary care, medications, and DMP workload with associated costs were evaluated assessing DMP clinic-visits, telephonic contact, medication changes over 1year using a mixture of casemix and micro-costing techniques.

RESULTS

The total average annual cost per patient was marginally higher in patients with HFrEF €13,011 (12,011, 14,078) than HFpEF, €12,206 (11,009, 13,518). However, emergency non-cardiovascular admission rates and average cost per patient were higher in the HFpEF vs HFrEF group (0.46 vs 0.31 per patient/12months) & €655 (318, 1073) vs €584 (396, 812). In the first 3months of the outpatient HF-DMP the HFrEF population cost more on average €791 (764, 819) vs €693 (660, 728).

CONCLUSION

There are greater short-term (3-month) costs of HFrEF versus HFpEF as part of a HF-DMP following an admission. However, long-term (3-12month) costs of HFpEF are greater because of higher non-cardiovascular rehospitalisations. As HFpEF becomes the dominant form of HF, more work is required in HF-DMPs to address prevention of non-cardiovascular rehospitalisations and to integrate hospital based HF-DMPs into primary healthcare structures.

Ovalbumin sensitization of guinea pig at birth prevents the ontogenetic decrease in airway smooth muscle responsiveness

Airway smooth muscle (ASM) displays a hyperresponsive phenotype at young age and becomes less responsive in adulthood. We hypothesized that allergic sensitization, which causes ASM hyperresponsiveness and typically occurs early in life, prevents the ontogenetic loss of the ASM hyperresponsive phenotype. We therefore studied whether neonatal allergic sensitization, not followed by later allergen challenges, alters the ontogenesis of ASM properties. We neonatally sensitized guinea pigs to ovalbumin and studied them at 1 week, 3 weeks, and 3 months (adult). A Schultz‐Dale response in isolated tracheal rings confirmed sensitization. The occurrence of inflammation was evaluated in the blood and in the submucosa of large airways. We assessed ASM function in tracheal strips as ability to produce force and shortening. ASM content of vimentin was also studied. A Schultz‐Dale response was observed in all 3‐week or older sensitized animals. A mild inflammatory process was characterized by eosinophilia in the blood and in the airway submucosa. Early life sensitization had no effect on ASM force generation, but prevented the ontogenetic decline of shortening velocity and the increase in resistance to shortening. Vimentin increased with age in control but not in sensitized animals. Allergic sensitization at birth without subsequent allergen exposures is sufficient to prevent normal ASM ontogenesis, inducing persistence to adulthood of an ASM hyperresponsive phenotype.

Airway smooth muscle (ASM) displays a hyperresponsive phenotype at young age and becomes less responsive in adulthood. In this study, we found that allergic sensitization at birth without subsequent allergen exposures is sufficient to prevent normal ASM ontogenesis, inducing persistence to adulthood of an ASM hyperresponsive phenotype.

Genetic variation in DNMT3B and increased global DNA methylation is associated with suicide attempts in psychiatric patients

Recently, a significant epigenetic component in the pathology of suicide has been realized. Here we investigate candidate functional SNPs in epigenetic-regulatory genes, DNMT1 and DNMT3B, for association with suicide attempt (SA) among patients with co-existing psychiatric illness. In addition, global DNA methylation levels [5-methyl cytosine (5-mC%)] between SA and psychiatric controls were quantified using the Methylflash Methylated DNA Quantification Kit. DNA was obtained from blood of 79 suicide attempters and 80 non-attempters, assessed for DSM-IV Axis I disorders. Functional SNPs were selected for each gene (DNMT1; n = 7, DNMT3B; n = 10), and genotyped. A SNP (rs2424932) residing in the 3' UTR of the DNMT3B gene was associated with SA compared with a non-attempter control group (P = 0.001; Chi-squared test, Bonferroni adjusted P value = 0.02). Moreover, haplotype analysis identified a DNMT3B haplotype which differed between cases and controls, however this association did not hold after Bonferroni correction (P = 0.01, Bonferroni adjusted P value = 0.56). Global methylation analysis showed that psychiatric patients with a history of SA had significantly higher levels of global DNA methylation compared with controls (P = 0.018, Student's t-test). In conclusion, this is the first report investigating polymorphisms in DNMT genes and global DNA methylation quantification in SA risk. Preliminary findings suggest that allelic variability in DNMT3B may be relevant to the underlying diathesis for suicidal acts and our findings support the hypothesis that aberrant DNA methylation profiles may contribute to the biology of suicidal acts. Thus, analysis of global DNA hypermethylation in blood may represent a biomarker for increased SA risk in psychiatric patients.

Airway contractility and remodeling: links to asthma symptoms

Respiratory symptoms are largely caused by obstruction of the airways. In asthma, airway narrowing mediated by airway smooth muscle (ASM) contraction contributes significantly to obstruction. The spasmogens produced following exposure to environmental triggers, such as viruses or allergens, are initially responsible for ASM activation. However, the extent of narrowing of the airway lumen due to ASM shortening can be influenced by many factors and it remains a real challenge to decipher the exact role of ASM in causing asthmatic symptoms. Innovative tools, such as the forced oscillation technique, continue to develop and have been proven useful to assess some features of ASM function in vivo. Despite these technologic advances, it is still not clear whether excessive narrowing in asthma is driven by ASM abnormalities, by other alterations in non-muscle factors or simply because of the overexpression of spasmogens. This is because a multitude of forces are acting on the airway wall, and because not only are these forces constantly changing but they are also intricately interconnected. To counteract these limitations, investigators have utilized in vitro and ex vivo systems to assess and compare asthmatic and non-asthmatic ASM contractility. This review describes: 1- some muscle and non-muscle factors that are altered in asthma that may lead to airway narrowing and asthma symptoms; 2- some technologies such as the forced oscillation technique that have the potential to unveil the role of ASM in airway narrowing in vivo; and 3- some data from ex vivo and in vitro methods that probe the possibility that airway hyperresponsiveness is due to the altered environment surrounding the ASM or, alternatively, to a hypercontractile ASM phenotype that can be either innate or acquired.

Modelling Cryptosporidium oocysts transport in small ungauged agricultural catchments

Cryptosporidium is an environmentally robust pathogen that has caused severe waterborne disease outbreaks worldwide. The main source of zoonotic Cryptosporidium parvum oocysts in human drinking water is likely to be from farm animals via catchment pathways with water as the main transport vector. The vast majority of small agricultural catchments are ungauged therefore it is difficult to use a process model to predict and understand the mechanisms and activities that regulate the risk of surface water contamination from agricultural areas. For this study, two ungauged agricultural catchments in Ireland were used to model Cryptosporidium oocyst transport using SWAT2005 on a daily basis with reference data from adjacent catchment gauging stations. The results indicated that SWAT2005 could simulate stream flow with good agreement between prediction and observation on a monthly basis (R(2) from 0.94 to 0.83 and E (efficiency) from 0.92 to 0.66), but Cryptosporidium oocyst concentration results were less reliable (R(2) from 0.20 to 0.37, P < 0.05; with poor E -0.37 to -2.57). A sensitivity analysis using independent parameter perturbation indicated that temperature was the most important parameter regulating oocyst transport in the study catchments and that the timing of manure application relative to the occurrence of water runoff event was critical. The results also showed that grazing management had little influence on predicted oocyst transport while fields fertilized with manure were the key critical source areas for microbial contaminations in the study catchments. It was concluded that the approach presented could be used to assist with understanding the epidemiology of waterborne cryptosporidiosis outbreaks and to improve catchment management for the safety of the general public health.

Babesias of red deer (Cervus elaphus) in Ireland

Blood samples were obtained from 38 wild red deer (Cervus elaphus) at two sites in Ireland and subjected to PCR analysis of the 18S rRNA gene followed by sequencing. Two fragments of the 18S rRNA gene were generated by two different PCR protocols and subsequent sequencing suggested that at least six of the deer were infected by a babesia that, in those loci, is indistinguishable from Babesia divergens, an important tick-borne pathogen of cattle and of zoonotic significance. Additionally, a B. odocoilei-like parasite was detected in three samples and a babesia that did not match any sequences in the GenBank database was found in five samples. Neither B. capreoli nor B. venatorum (EU1) were found. There have been several reports of B. divergens occurring in deer species, including red deer, roe deer (Capreolus capreolus) and reindeer (Rangifer tarandus). However, in view of recent re-sequencing of bovine-origin samples deposited previously in GenBank, it is unlikely that any of these sequences from deer are B. divergens. The present study describes the only deer piroplasm detected so far that shows complete identity with B. divergens, in just over half of the 18S rRNA gene. The entire gene of this deer parasite should be analysed and transmission experiments undertaken before the infectivity of B. divergens for red deer can be confirmed.

Control of cryptosporidiosis in neonatal calves: use of halofuginone lactate in two different calf rearing systems

To date there is no effective treatment for bovine cryptosporidiosis. This study describes the use of halofuginone lactate in preventing cryptosporidiosis in naturally infected neonatal calves on a dairy farm with a high prevalence of infection. The animals were kept in two different calf rearing systems. A randomized double-blind trial was carried out with 32 naturally infected calves, divided into four groups. The two prophylactic halofuginone lactate treated groups were kept in either individual or group pens. Similarly, the animals receiving the placebo were housed in either individual pens or together in a large pen. A total of ten faecal samples were collected periodically during the 28 days study from each calf and tested for the presence of Cryptosporidium spp. using microscopic and molecular methods. Generalized estimating equations models were used to determine if the effects of the various treatments and/or rearing systems on the presence of diarrhoea and infection were statistically significant. Further analysis (classification trees models) was carried out to explore possible risk factors for cryptosporidiosis and interactions between treatments and rearing systems. Halofuginone lactate was shown to be effective in reducing clinical signs of cryptosporidiosis and environmental contamination. However, the treatment did not delay the onset of diarrhoea and did not reduce the risk of infection amongst calves reared together in a highly contaminated environment. The use of halofuginone lactate in combination with good hygienic measures, such as rearing animals in clean individual pens, was the most effective method to reduce the risk of cryptosporidiosis amongst 7-13 days old calves. It was concluded that the control of the parasite could be achieved by the combination of using effective preventive drugs, such as halofuginone lactate and good animal husbandry procedures.

Spatial distribution of risk factors for Cryptosporidium spp. transport in an Irish catchment

Cryptosporidium spp. has become a major public health concern in many parts of the globe, including Ireland, as a result of recent reported waterborne outbreaks of Cryptosporidiosis. Continuous monitoring of Cryptosporidium spp. in water supplies is not feasible, so a risk-forecasting approach is required. This study reports a globally applicable approach for evaluating the spatial variation in relative risk of contaminating surface water by Cryptosporidium spp. based on a risk potential index (RPI) as an indicator of the potential pollution of surface water. The RPI is predicted by readily available data on land use, rainfall, soil type, slope, soil moisture deficit, and distance from water course. A small catchment in County Meath, Ireland, was chosen to illustrate the analysis of the approach. Data for the study area were digitized and rectified using surveyed ground control points to capture each of the RPI factors, field boundaries, and land use. The six parameters were classified and assigned a relative risk score out of 5. A Geographic Information Systems overlay analysis then was used to calculate a cumulative relative risk score for each month of the year. The analysis indicated that April and June experienced a relatively low risk of Cryptosporidium spp. transport compared with other months of the year. June had the least risk, because more than 98% of the catchment was estimated to be of low or moderate risk (RPI ranges = 0 to 2). December had the highest risk of Cryptosporidium spp. transport, because approximately 20% of the catchment area had a moderately high to very high risk (RPI ranges = 2 to 5). The study also made an attempt to reduce the risk of contaminating surface water by alternative land-use practice and relocating the field boundaries. The study demonstrated a semi-quantitative and readily implemented method for using spatial risk assessment for planning land management to reduce the risk of surface water contamination by Cryptosporidium spp. from agricultural sources. The approach could be used in any catchment with similar hydrological characteristics subject to a surface water pathogen contamination risk from grazing livestock.

Anisakid larvae in Atlantic salmon (Salmo salar L.) grilse and post-smolts: molecular identification and histopathology

The molecular identification and histopathology are described for the parasitic larvae of a nematode species present in the abdominal cavity of Atlantic salmon ( Salmo salar ) grilse caught in fish traps on their natal river in the west of Ireland and post-smolts collected during experimental trawls on the continental shelf edge of the northeast Atlantic Ocean. Larvae in the adult and juvenile salmon were identified as Anisakis simplex sensu stricto by PCR amplification and RFLP and sequencing of the ITS gene and PCR amplification and sequencing of the cox2 gene. Parasitic nematode larvae in the grilse were either encapsulated in the abdominal mesentery associated with the pyloric ceca or on the serosal surface of the liver and in the vent region. In some fish, larvae were found in the parenchyma of the liver and muscularis circularis of the intestine. In general, the larvae induced a limited cellular response apart from the occurrence of focal melanin macrophage aggregates and individual eosinophilic granular cells in the connective tissue capsule. Melanin macrophage aggregates were also present among the hepatocytes adjacent to encapsulated larvae in the liver. The reaction to the parasites was more severe in the wall of the intestine. Encapsulated nematode larvae caused displacement, vacuolation, and necrosis of the circular muscle fibers. The stratum compactum was also disrupted with focal areas of degeneration. Overall, the intestinal wall had a hypercellular appearance with extensive cellular infiltration comprising eosinophilic granular cells, macrophages, lymphocytes, and fibrocytes. The post-smolts were caught in May during the early oceanic phase of their life cycle. In these fish, A. simplex sensu stricto larvae were found lying free on the serosal surface of the intestine and liver without any apparent histologic changes. This is the earliest in the marine migration of Atlantic salmon that A. simplex sensu stricto infection has been recorded.

Trends in the clinical characteristics of the U.S. cystic fibrosis patient population from 1995 to 2005

RATIONALE

Respiratory signs and symptoms (cough, sputum production, or crackles) are considered bellwethers of underlying cystic fibrosis (CF) lung disease. If respiratory signs and symptoms predict future lung function loss, then improvements in population lung function over the past decade should have been paralleled by a decrease in the prevalence of these variables in the same population. Additionally, changes in these variables over the past decade may provide insight into the improving health of the CF population.

METHODS

Cross-sectional data from the Epidemiologic Study of Cystic Fibrosis for each year between 1995 and 2005 were analyzed to characterize changes in pulmonary function and respiratory signs and symptoms over time. Patients were separated into five age groups: <6, 6-12, 13-17, 18-24, and >or=25 years.

RESULTS

Serial cross-sectional analyses of an average of 13,381 patients per year indicated that mean pulmonary function for the CF population improved and the percent of patients reporting cough or sputum production or having crackles or wheeze at their clinic visit decreased over the study period. Observed changes in pulmonary function were not consistently mirrored by changes in symptoms, which differed as a function of the variable studied and the age group.

CONCLUSIONS

Reductions in respiratory signs and symptoms have paralleled improvements in pulmonary function. Both the absolute and relative magnitude of changes in prevalence for cough, sputum production, crackles, and wheeze differed among age groups and among variables. These results suggest the possibility that differences in respiratory signs and symptoms may arise from different underlying pathologies and may be influenced differently by therapeutic interventions.

Reduced spontaneous relaxation in immature guinea pig airway smooth muscle is associated with increased prostanoid release

Airway smooth muscle (ASM) from infant guinea pigs has less spontaneous relaxation during stimulation than ASM from adults. Inhibition of cyclooxygenase (COX), which catalyzes the production of prostanoids, increases this relaxation in infant ASM and abolishes age differences, thus suggesting that prostanoids reduce relaxation in infant ASM. In this study, we investigated whether leukotrienes are also involved in reducing spontaneous relaxation; whether the two COX isoforms, COX-1 and COX-2, differentially regulate spontaneous relaxation; and whether prostanoid release is developmentally regulated in guinea pig ASM. In different age groups, we measured relaxation during and after electrical stimulation in tracheal strips as well as prostanoid release from tracheal segments. Relaxation was studied in the absence and in the presence of a lipoxygenase inhibitor, a cysteinyl leukotriene receptor-1 antagonist, a COX-1 inhibitor, or a COX-2 inhibitor. We found that inhibition of lipoxygenase or cysteinyl leukotriene receptor-1 antagonism did not increase spontaneous relaxation at any age, thus excluding a role for leukotrienes in this phenomenon. Inhibition of COX-2, but not COX-1, promoted spontaneous relaxation. The basal release of prostanoids was more abundant in tissue from infant animals and decreased significantly with age. Thromboxane B2 was the most abundant metabolite released at all ages. Electrical stimulation and epithelium removal did not affect the age difference in prostanoid release. We conclude that increased basal prostanoid release contributes to the reduced spontaneous relaxation in immature guinea pig ASM compared with older animals. By regulating ASM relaxation, prostanoids may play a role in the airway hyperresponsiveness at a young age.

The emergence of DNA methylation as a key modulator of aberrant cell death in prostate cancer

It is now well established that cancer cells exhibit a number of genetic defects in the machinery that governs programmed cell death and that sabotage of apoptosis is one of the principal factors aiding in the evolution of the carcinogenic phenotype. A number of studies have implicated aberrant DNA methylation as a key survival mechanism in cancer, whereby promoter hypermethylation silences genes essential for many processes including apoptosis. To date, studies on the methylation profile of apoptotic genes have largely focused on cancers of the breast, colon and stomach, with only limited data available on prostate cancer. Here we discuss the major developments in the field of DNA methylation and its role in the regulation of aberrant apoptosis in prostate cancer. The most significant advances have involved the discovery of apoptotic gene targets of methylation, including XAF1, (fragile histidine triad (FHIT ), cellular retinol binding protein 1 (CRBP1), decoy receptor 1(DCR1), decoy receptor 2 (DCR2 ), target of methylation-induced silenceing 1 (TMS1), TNF receptor superfamily, member 6 (FAS), Reprimo (RPRM) and GLI pathogenesis-related 1 (GLIPR1). These genes are reported to be hypermethylated in prostate cancer and some offer potential as diagnostic and prognostic markers. We also introduce the concept of an 'apoptotic methylation signature' for prostate cancer and evaluate its potential in a diagnostic, prognostic and therapeutic setting.

Three paradigms of airway smooth muscle hyperresponsiveness in young guinea pigs

Evidence for contributions of airway smooth muscle (ASM) to the hyperresponsiveness of newborn and juvenile airways continues to accumulate. In our laboratory, 3 novel paradigms of hyperresponsiveness of newborn and young ASM have recently emerged using a guinea pig model of maturation in 3 age groups: 1 week (newborn), 3 weeks (juvenile), and 2-3 months (adult). The first paradigm includes evidence for a natural decline after newborn and juvenile life of the velocity of ASM shortening associated with a decrease in regulatory myosin light chain phosphorylation and a parallel decline in the content of myosin light chain kinase. Associated with the decrease in ASM shortening with age is an increase in the internal resistance to shortening. Dynamic stiffness is shown to relate inversely to the expression of myosin light chain kinase. This suggests that developmental changes in shortening relate inversely to the stiffness of the ASM early in shortening, suggesting a dynamic role for the cytoskeleton in facilitating and opposing ASM shortening. This relationship can be approximated as (dP/dt)max approximately (dP/dL)passive x (dL/dt)max (the maximal rate of increase of active stress generation approximately to the passive stiffness x the maximal shortening velocity). The second paradigm demonstrates that newborn ASM, unlike that in adults, does not relax during prolonged electric field stimulation. The impaired relaxation is related to changes in prostanoid synthesis and acetylcholinesterase function. The third paradigm demonstrates that, whereas oscillatory strain serves to transiently relax adult ASM, in newborns it induces (after the initial relaxation) a sustained potentiation of active stress. This is related to developmental changes in the prostanoid release. Together, these paradigms demonstrate that ASM contributes by multiple mechanisms to the natural hyperresponsiveness of newborn and juvenile airways. Future studies will elaborate the mechanisms and extend these paradigms to ASM hyperresponsiveness following sensitization in early life.

Airway smooth muscle relaxation is impaired in mice lacking the p47phox subunit of NAD(P)H oxidase

NAD(P)H oxidase is one of the critical enzymes mediating cellular production of reactive oxygen species and has a central role in airway smooth muscle (ASM) cell proliferation. Since reactive oxygen species also affect ASM contractile response, we hypothesized a regulatory role of NAD(P)H oxidase in ASM contractility. We therefore studied ASM function in wild-type mice (C57BL/6J) and mice deficient in a component (p47phox) of NAD(P)H oxidase. In histological sections of the trachea, we found that the area occupied by ASM was 17% more in p47(phox-/-) than in wild-type mice. After correcting for the difference in ASM content, we found that force generation did not vary between the two genotypes. Similarly, their ASM shortening velocity, maximal power, and sensitivity to acetylcholine, as well as airway responsiveness to methacholine in vivo, were not significantly different. The main finding of this study was a significantly reduced ASM relaxation in p47phox-/- compared with wild-type mice both during the stimulus and after the end of stimulation. The tension relaxation attained at the 20th second of electric field stimulation was, respectively, 17.6 +/- 2.4 and 9.2 +/- 2.3% in null and wild-type mice (P <0.01 by t-test). Similar significant differences were found in the rate of tension relaxation and the time required to reduce tension by one-half. Our data suggest that NAD(P)H oxidase may have a role in the structural arrangement and mechanical properties of the airway tissue. Most importantly, we report the first evidence that the p47phox subunit of NAD(P)H oxidase plays a role in ASM relaxation.

Investigation of the link between avian vacuolar myelinopathy and a novel species of cyanobacteria through laboratory feeding trials

Avian vacuolar myelinopathy (AVM) is a neurologic disease affecting Bald Eagles (Haliaeetus leucocephalus), American Coots (Fulica americana), and other birds in the southeastern United States. The cause of the disease has not yet been determined, although it is generally thought to be a natural toxin. Previous studies have linked AVM to aquatic vegetation, and the current working hypothesis is that a species of cyanobacteria growing epiphytically on that vegetation is producing a toxin that causes AVM. Surveys of epiphytic communities have identified a novel species of cyanobacteria in the order Stigonematales as the most likely suspect. The purpose of this study was to further examine the relationship between the suspect Stigonematales species and induction of AVM, by using animal feeding trials. Adult Mallards and domestic chickens were fed aquatic vegetation from two study sites containing the suspect cyanobacterial epiphyte, as well as a control site that did not contain the Stigonematales species. Two trials were conducted. The first trial used vegetation collected during mid-October 2003, and the second trial used vegetation collected during November and December 2003. Neither treatment nor control birds in the first trial developed AVM lesions. Ten of 12 treatment Mallards in the second trial were diagnosed with AVM, and control birds were not affected. This study provides further evidence that the novel Stigonematales species may be involved with AVM induction, or at the least it is a good predictor of AVM toxin presence in a system. The results also demonstrate the seasonal nature of AVM events.

Shape representation by a network of V4-like cells

Cells in extrastriate visual cortex have been reported to be selective for various configurations of local contour shape [Pasupathy, A., & Connor, C. E. (2001). Shape representation in area V4: Position-specific tuning for boundary conformation. The Journal of Neurophysiology, 86 (5), 2505-2519; Hegdé, J., & Van Essen, D. C. (2003). Strategies of shape representation in macaque visual area V2. Visual Neuroscience, 20 (3), 313-328]. Specifically, Pasupathy and Connor found that in area V4 most cells are strongly responsive to a particular local contour conformation located at a specific position on the object's boundary. We used a population of "V4-like cells"-units sensitive to multiple shape features modeled after V4 cell behavior-to generate representations of different shapes. Standard classification algorithms (earth mover's distance, support vector machines) applied to this population representation demonstrate high recognition accuracies classifying handwritten digits in the MNIST database and objects in the MPEG-7 Shape Silhouette database. We compare the performance of the V4-like unit representation to the "shape context" representation of Belongie et al. [Belongie, S., Malik, J., & Puzicha, J. (2002). Shape matching and object recognition using shape contexts. IEEE Transactions on Pattern Analysis and Machine Intelligence, 24 (24), 509-522]. Results show roughly comparable recognition accuracies using the two representations when tested on portions of the MNIST database. We analyze the relative contributions of various V4-like feature sensitivities to recognition accuracy and robustness to noise - feature sensitivities include curvature magnitude, direction of curvature, global orientation of the contour segment, distance of the contour segment from object center, and modulatory effect of adjacent contour regions. Among these, local curvature appears to be the most informative variable for shape recognition. Our results support the hypothesis that V4 cells function as robust shape descriptors in the early stages of object recognition.

Study on the prevalence of Toxoplasma gondii and Neospora caninum and molecular evidence of Encephalitozoon cuniculi and Encephalitozoon (Septata) intestinalis infections in red foxes (Vulpes vulpes) in rural Ireland

Thoracic fluid (pleural fluid and clotted blood) from 206 foxes were examined for antibodies to Toxoplasma gondii and 220 thoracic fluid samples were tested for Neospora caninum antibodies using indirect immunofluorescent antibody tests (IFAT). A total of 115 (56%) and six (3%) foxes had antibodies to T. gondii and N. caninum, respectively. The brains from 148 foxes were examined for histological lesions and pathological changes suggestive of parasitic encephalitis were observed in 33 (22%). Two thirds of these foxes had antibodies to T. gondii and one fox had antibodies to both T. gondii and N. caninum. PCR assays carried out on DNA extracted from the 33 brains with histological lesions were negative for N. caninum but one of the brains was positive for T. gondii. Microsporidian DNA was also amplified from the brains of two of these foxes. Sequencing these amplicons revealed 100% homology with Encephalitozoon (Septata) intestinalis in one fox and Encephalitozoon cuniculi in the second fox. This is the first report of Encephalitozoon infections in wildlife in Ireland.

Nox4 mediates TGF-beta1-induced retinoblastoma protein phosphorylation, proliferation, and hypertrophy in human airway smooth muscle cells

Transforming growth factor-beta1 (TGF-beta1) plays a pivotal role in increasing airway smooth muscle mass in severe asthma by inducing proliferation and hypertrophy of human airway smooth muscle. The mechanism(s) for these effects of TGF-beta1 have not been fully elucidated. In this study, we demonstrate that TGF-beta1 is a potent inducer of expression of the nonphagocyte NAD(P)H oxidase catalytic homolog Nox4, diphenylene iodonium-inhibitable reactive oxygen species production, proliferation, and hypertrophy in cultured human airway smooth muscle cells. By confocal microscopy, TGF-beta1-induced Nox4 was localized with the endoplasmic reticulum and the nucleus, implying a role for Nox4 in regulation of both the cell cycle and protein synthesis. Consistent with this hypothesis, TGF-beta1 increased retinoblastoma protein phosphorylation at both Ser807/811 and Ser780. Silencing Nox4 prevented TGF-beta1-mediated retinoblastoma protein phosphorylation, proliferation, and cell hypertrophy. TGF-beta1 also increased phosphorylation of eukaryotic translation initiation factor 4E binding protein-1 at Thr37/46, and this was likewise blocked by silencing Nox4. This is the first report to suggest a functional role for Nox4 in cell cycle transition and to demonstrate that Nox4 influences the pathobiochemistry of asthma by generating reactive oxygen species that promote TGF-beta1-induced proliferation and hypertrophy of human airway smooth muscle.

A study of helminth parasites in culled cows from Ireland

The objective of this study was to determine the prevalence and intensity of gastrointestinal nematode, lungworm and liver fluke infection in culled cows in Ireland. Abomasa, colorectal contents and livers were collected from 30 to 68 culled beef and dairy cows during autumn 2002 and summer 2003, respectively. Ostertagia ostertagi were found in the abomasa of only three (10%) cows sampled in autumn and in 38 (57%) cows examined in summer. The majority of positive animals had low burdens of O. ostertagi but a few individuals in the group sampled during the summer had a moderate infection (5000-10,000 adult worms). A proportion of the cows in the summer group were also co-infected with small numbers of Trichostrongylus axei. Cooperia oncophora predominated in the recoveries from the larval cultures although O. ostertagi were also recovered. The overall prevalence of Dictyocaulus viviparus was 14%, based on larval identification in faecal samples. Liver fluke, or varying degrees of pathology attributable to Fasciola hepatica, were present in 65% of the livers. The results of this study extend those of previous workers, which were largely limited to dairy cows alone and which focussed on gastrointestinal nematodes and did not include simultaneous infections with lungworm and liver fluke. It was concluded, from the level of polyparasitism evident in this study, that adult cattle should be considered in preventative approaches to bovine helminthosis.

Prevalence and identity of Cryptosporidium spp. in pig slurry

Cryptosporidium spp. were detected in 25 of 56 pig slurry samples from 33 Irish farms by PCR and DNA sequencing. The organisms detected included C. suis, Cryptosporidium pig genotype II, and C. muris. We concluded that Cryptosporidium oocysts can persist in treated slurry and potentially contaminate surface water through improper discharge or uncontrolled runoff.

Mechanisms of airway smooth muscle relaxation during maturation

Greater airway responsiveness in healthy juveniles is considered a factor in the higher asthma prevalence at a young age compared with adults. We have developed a guinea pig maturational model that utilizes tracheal strips from 1-week-, 3-week-, and 3-month-old guinea pigs to study the role of airway smooth muscle (ASM) in juvenile airway hyperresponsiveness. Because a reduced ability of ASM to spontaneously relax may contribute to airway hyperresponsiveness by maintaining bronchospasm and thus high airway resistance, we have employed this model to study ASM spontaneous relaxation during electrical field stimulation (EFS). Since relaxation during EFS had been neither described nor quantified during maturation, we developed new indices that allowed an appropriate comparison of the relaxing response from strips of different age animals. Using these indices we found that, whereas strips from adult animals relax to a level of tension similar to that found in the absence of stimulation, this ability to spontaneously relax is essentially absent in trachealis from infant animals. These results confirmed that maturation of ASM relaxation may play a role in juvenile airway hyperresponsiveness and that our maturational model is suitable to study the mechanisms regulating spontaneous relaxation in physiological conditions. We investigated the role of prostanoids in ASM relaxation and showed that cyclooxygenase inhibition increases relaxation in infant ASM to levels similar to adults. These results suggest that prostanoids regulate the ability of ASM to spontaneously relax, i.e., they reduce relaxation. We have produced preliminary data suggesting a maturational change in the level of prostanoids. Moreover, the possible action of acetylcholinesterase on maturation of ASM relaxation is discussed here on the basis of a preliminary study. We suggest that impairment of ASM relaxation likely contributes to increased airway responsiveness.

A maturational model for the study of airway smooth muscle adaptation to mechanical oscillation

It has been shown that mechanical stretches imposed on airway smooth muscle (ASM) by deep inspiration reduce the subsequent contractile response of the ASM. This passive maneuver of lengthening and retraction of the muscle is beneficial in normal subjects to counteract bronchospasm. However, it is detrimental to hyperresponsive airways because it triggers further bronchoconstriction. Although the exact mechanisms for this contrary response by normal and hyperresponsive airways are unclear, it has been suggested that the phenomenon is related to changes in ASM adaptability to mechanical oscillation. Healthy immature airways of both human and animal exhibit hyperresponsiveness, but whether the adaptative properties of hyperresponsive airway differ from normal is still unknown. In this article, we review the phenomenon of ASM adaptation to mechanical oscillation and its relevance and implication to airway hyperresponsiveness. We demonstrate that the age-specific expression of ASM adaptation is prominent using an established maturational animal model developed in our laboratory. Our data on immature ASM showed potentiated contractile force shortly after a length oscillation compared with the maximum force generated before oscillation. Several potential mechanisms such as myogenic response, changes in actin polymerization, or changes in the quantity of the cytoskeletal regulatory proteins plectin and vimentin, which may underlie this age-specific force potentiation, are discussed. We suggest a working model of the structure of smooth muscle associated with force transmission, which may help to elucidate the mechanisms responsible for the age-specific expression of smooth muscle adaptation. It is important to study the maturational profile of ASM adaptation as it could contribute to juvenile hyperresponsiveness.Key words: ASM adaptation, maturation, bronchoprotection, airway hyperresponsiveness.

Maturation of guinea pig tracheal strip stiffness

Previously, we showed the shortening velocity of guinea pig tracheal strips was the greatest in juvenile (3-wk-old) compared with infant (1-wk-old) and adult animals (3-mo-old). The greatest shortening velocity was associated with the least resistance to shortening calculated from force-velocity curves among the three age groups. It remained to be verified if the stiffness of tracheal tissue, a measure of tissue response to geometrical deformations, is different among the three age groups. We hypothesized that stiffness of intact tracheal strips is lowest in the juvenile group and that this can explain the ontogeny of airway smooth muscle resistance to shortening and shortening velocity. Static stiffness measured through stepwise deformations showed no age-related differences. Evaluation of tissue response to oscillatory deformations showed that the dynamic stiffness of unstimulated tracheal strips was 8.35 +/- 0.88, 4.15 +/- 1.09, and 8.21 +/- 1.57 kPa, and the phase angle was 10.3 +/- 2.93, 2.46 +/- 0.67, and 7.87 +/- 1.77 degrees in infant, juvenile, and adult, respectively. Unstimulated juvenile strips were significantly lower in dynamic stiffness and phase angle compared with unstimulated infant or adult strips. This maturational profile was independent of muscle strip preset length or oscillation mode/amplitude but was abolished at peak of contraction to either carbachol or electric field stimulation. These results suggest that the noncontractile components of tracheal strips are less stiff and contain fewer viscous/frictional elements in juvenile than in other age groups. This may provide a functional basis for reduced resistance to length changes in juvenile airway smooth muscle.

Length oscillation induces force potentiation in infant guinea pig airway smooth muscle

Deep inspiration counteracts bronchospasm in normal subjects but triggers further bronchoconstriction in hyperresponsive airways. Although the exact mechanisms for this contrary response by normal and hyperresponsive airways are unclear, it has been suggested that the phenomenon is related to changes in force-generating ability of airway smooth muscle after mechanical oscillation. It is known that healthy immature airways of both humans and animals exhibit hyperresponsiveness. We hypothesize that the profile of active force generation after mechanical oscillation changes with maturation and that this change contributes to the expression of airway hyperresponsiveness in juveniles. We examined the effect of an acute sinusoidal length oscillation on the force-generating ability of tracheal smooth muscle from 1 wk, 3 wk, and 2- to 3-mo-old guinea pigs. We found that the length oscillation produced 15-20% initial reduction in active force equally in all age groups. This was followed by a force recovery profile that displayed striking maturation-specific features. Unique to tracheal strips from 1-wk-old animals, active force potentiated beyond the maximal force generated before oscillation. We also found that actin polymerization was required in force recovery and that prostanoids contributed to the maturation-specific force potentiation in immature airway smooth muscle. Our results suggest a potentiated mechanosensitive contractile property of hyperresponsive airway smooth muscle. This can account for further bronchoconstriction triggered by deep inspiration in hyperresponsive airways.

Avian vacuolar myelinopathy linked to exotic aquatic plants and a novel cyanobacterial species

Invasions of exotic species have created environmental havoc through competition and displacement of native plants and animals. The introduction of hydrilla (Hydrilla verticillata) into the United States in the 1960s has been detrimental to navigation, power generation, water intake, and water quality (McCann et al., 1996). Our field surveys and feeding studies have now implicated exotic hydrilla and associated epiphytic cyanobacterial species as a link to avian vacuolar myelinopathy (AVM), an emerging avian disease affecting herbivorous waterbirds and their avian predators. AVM, first reported in 1994, has caused the death of at least 100 bald eagles (Haliaeetus leucocephalus) and thousands of American coots (Fulica americana) at 11 sites from Texas to North Carolina (Thomas et al., 1998; Rocke et al., 2002). Our working hypothesis is that the agent of this disease is an uncharacterized neurotoxin produced by a novel cyanobacterial epiphyte of the order Stigonematales. This undescribed species covers up to 95% of the surface area of leaves in reservoirs where bird deaths have occurred from the disease. In addition, this species is rare or not found on hydrilla collected at sites where AVM disease has not been diagnosed. Laboratory feeding trials and a sentinel bird study using naturally occurring blooms of cyanobacteria on hydrilla leaves and farm-raised mallard ducks (Anas platyrhynchos) induced the disease experimentally. Since 1994 AVM has been diagnosed in additional sites from Texas to North Carolina. Specific site characteristics that produce the disjunct distribution of AVM are unknown, but it is probable that the incidence of this disease will increase with the introduction of hydrilla and associated cyanobacterial species into additional ponds, lakes, and reservoirs.

On the terminology for describing the length-force relationship and its changes in airway smooth muscle

The observation that the length-force relationship in airway smooth muscle can be shifted along the length axis by accommodating the muscle at different lengths has stimulated great interest. In light of the recent understanding of the dynamic nature of length-force relationship, many of our concepts regarding smooth muscle mechanical properties, including the notion that the muscle possesses a unique optimal length that correlates to maximal force generation, are likely to be incorrect. To facilitate accurate and efficient communication among scientists interested in the function of airway smooth muscle, a revised and collectively accepted nomenclature describing the adaptive and dynamic nature of the length-force relationship will be invaluable. Setting aside the issue of underlying mechanism, the purpose of this article is to define terminology that will aid investigators in describing observed phenomena. In particular, we recommend that the term "optimal length" (or any other term implying a unique length that correlates with maximal force generation) for airway smooth muscle be avoided. Instead, the in situ length or an arbitrary but clearly defined reference length should be used. We propose the usage of "length adaptation" to describe the phenomenon whereby the length-force curve of a muscle shifts along the length axis due to accommodation of the muscle at different lengths. We also discuss frequently used terms that do not have commonly accepted definitions that should be used cautiously.

Establishing a food-chain link between aquatic plant material and avian vacuolar myelinopathy in mallards (Anas platyrhynchos)

Avian vacuolar myelinopathy (AVM) is a neurologic disease primarily affecting bald eagles (Haliaeetus leucocephalus) and American coots (Fulica americana). The disease was first characterized in bald eagles in Arkansas in 1994 and then in American coots in 1996. To date, AVM has been confirmed in six additional avian species. Attempts to identify the etiology of AVM have been unsuccessful to date. The objective of this study was to evaluate dermal and oral routes of exposure of birds to hydrilla (Hydrilla verticillata) and associated materials to evaluate their ability to induce AVM. Mallards (Anas platyrhynchos) were used in all trials; bobwhite quail (Colinus virginianus) also were used in one fresh hydrilla material exposure trial. Five trials were conducted, including two fresh hydrilla material exposure trials, two cyanobacteria exposure trials, and a frozen hydrilla material exposure trial. The cyanobacteria exposure trials and frozen hydrilla material trial involved gavaging mallards with either Pseudanabaena catenata (live culture), Hapalosiphon fontinalis, or frozen hydrilla material with both cyanobacteria species present. With the exception of one fresh hydrilla exposure trial, results were negative or inconclusive. In the 2002 hydrilla material exposure trial, six of nine treated ducks had histologic lesions of AVM. This established the first cause-effect link between aquatic vegetation and AVM and provided evidence supporting an aquatic source for the causal agent.

Ontogenesis of myosin light chain phosphorylation in guinea pig tracheal smooth muscle

Increased airway responsiveness occurs in normal young individuals compared to adults. A maturation of airway smooth muscle (ASM) contractility is likely a mechanism of this juvenile airway hyperresponsiveness. Indeed, we showed in guinea pig tracheal smooth muscle (TSM) that maximum shortening velocity decreases dramatically after the first 3 weeks of life. Because the phosphorylation of the 20-kDa myosin light chain (MLC(20)) was shown to be a key event in ASM contractility, in the present work we sought to investigate it during ontogenesis. In three age groups (1-week-old, 3-week-old, and adult guinea pigs), we assessed the amount of MLC(20) phosphorylation achieved either in TSM crude protein homogenates exposed to Mg(2+) . ATP . CaCl(2) or in tracheal strips during electrical field stimulation (EFS). Phosphorylated and unphosphorylated MLC(20) were separated on nondenaturing 10% polyacrylamide gels, and the ratio of phosphorylation was obtained by densitometric analysis of chemiluminescent Western immunoblots. Maximum MLC(20) phosphorylation (% of total MLC(20)) in TSM tissue homogenate was, respectively, 32.6 +/- 5.7, 32.2 +/- 5.7, and 46.8 +/- 5.8 in 1-week, 3-week, and adult guinea pigs. Interestingly, in nonstimulated intact tracheal strips, we found a substantial degree of MLC(20) phosphorylation: respectively, 42.2 +/- 5.8, 36.5 +/- 7.8, and 46.4 +/- 4.7 in 1-week, 3-week, and adult guinea pigs. Maximal EFS-induced MLC(20) phosphorylation (% increase over baseline) in the 3-week age group was attained after 3 sec of EFS, and was 161.2 +/- 17.6, while in 1-week and adult guinea pigs, it was attained at 1.5 sec of EFS and was, respectively, 133.3 +/- 9.3 and 110.2 +/- 3.9 (P < 0.05). We conclude that MLC(20) phosphorylation in guinea pig intact tracheal strips correlates with ontogenetic changes in shortening velocity and changes in myosin light chain kinase content. These results further suggest that the maturation of ASM contractile properties plays a role in the greater airway responsiveness reported in children and young animals.

Ontogenesis of myosin light chain kinase mRNA and protein content in guinea pig tracheal smooth muscle

We previously reported in guinea pig tracheal smooth muscle that maximal shortening velocity decreases from 3 weeks of age to adulthood. It is not known whether myosin light chain kinase (MLCK), a key enzyme determining the velocity of smooth muscle contraction, undergoes maturational changes. In the present work, we investigated MLCK protein content and mRNA expression in 1-week-old, 3-week-old, and adult guinea pigs. We extracted either proteins or RNA from isolated tracheal smooth muscle. The content of MLCK was assessed by Western immunoblots. MLCK mRNA was evaluated by Northern analysis and by quantitative real time reverse transcriptase-polymerase chain reaction (RT-PCR). The content of MLCK increased 3-fold at 3 weeks of age and then decreased in adults, being 0.116 +/- 0.042, 0.330 +/- 0.125 (P < 0.05), and 0.153 +/- 0.054 microg/mg of total protein, respectively, in 1-week, 3-week, and adult animals. Quantitative RT-PCR revealed that MLCK mRNA increased with age to 135 +/- 35% and 177 +/- 23% (P < 0.01) in 3-week and adult animals, respectively, compared to 1-week animals. The transient increase of MLCK content in juvenile guinea pig tracheal smooth muscle may contribute to the increased shortening velocity at this age. We suggest that this increased content of MLCK is one of the mechanisms leading to maturation of airway smooth muscle contractility, which in turn contributes to the airway hyperresponsiveness reported in children and young animals.

Maturational changes in airway smooth muscle shortening and relaxation. Implications for asthma

Greater airway responsiveness in healthy juveniles is considered a factor in the higher asthma prevalence at a young age compared with adults. Several studies on the contractile response of airway smooth muscle (ASM) from birth to adulthood have addressed the hypothesis that a maturation of ASM plays a role in juvenile airway hyperresponsiveness. Maturation of distinct ASM properties, i.e. force generation, shortening, and relaxation, has been reported, although the majority of the studies have focused on maturation of maximum force and/or sensitivity to contractile agonists. However, in most animal species maturation of the ability to generate force does not correlate with maturation of airway responsiveness. Ontogenesis of ASM shortening has been less extensively studied and the existing reports emphasize an increase during maturation of tissue passive forces opposing shortening. ASM spontaneous relaxation has been very minimally investigated. We have recently demonstrated that the ability of ASM to spontaneously relax during stimulation is sharply reduced in juvenile airway tissue. It remains to be determined the role of these ASM properties in the onset of childhood asthma and whether specific alterations are induced by the occurrence of obstructive airway diseases in young individuals.

Mercury in bald eagle nestlings from South Carolina, USA

Bald eagles (Haliaeetus leucocephalus) may be at risk from contaminants in their diet and young birds may be particularly sensitive to contaminant exposure. To evaluate potential risks from dietary mercury exposure to eagle nestlings in South Carolina (USA), we surveyed mercury concentrations in 34 nestlings over two breeding seasons (1998 and 1999). Samples were also obtained from several post-fledging eagles in the region. Nestling feather mercury ranged from 0.61-6.67 micrograms Hg/g dry weight, nestling down mercury from 0.50-5.05 micrograms Hg/g dry weight, and nestling blood mercury from 0.02-0.25 microgram Hg/g wet weight. We did not detect significant differences in tissue mercury between nestlings from coastal and inland regions in contrast to some other studies of piscivorous birds. Mercury concentrations were much higher in the post fledging birds we sampled. Our data show that nestling eagles in South Carolina are accumulating mercury, and that concentrations in older birds may exceed regulatory guidelines.