Spectroscopic Studies of Ligand Interactions with Acetycholinesterase

A series of ligands with suitable spectroscopic properties have been employed for investigating the sites and specificity of ligand association with an acetylcholinesterase purified to apparent homogeneity from Torpedo californica. Bisquaternary ammonium .ligands in which the nitrogens are maximally separated by 14 A, bind with 1 : 1 stoichiometry with each 82 000 molecular weight subunit on acetylcholinesterase. Placement of a benzoquinone moiety between the quaternary nitrogens provides a ligand which upon binding quenches the tryptophanyl fluorescence of the protein. The complex exhibits 490/o of the fluorescence of the free protein and the quenching appears to take place by radiationless energy transfer between excited state dipoles. Since quenching appears uniform with binding on each subunit, it is unlikely that the ligand binding sites exist near a center or axis of symmetry between subunits. Modification of the active s ite serine forming the respective sulfonyl or phosphoryl esters enables one to study the orientation of the bound bisquaternary ligand with respect to the catalytic serine and the es.terifying group. Propidium, a second ligand, bililds to acetylcholinesterase with an enhancement in quantum yield and a shift in excitation and emission wavelengths. Propidium also exhibits binding which is stoichiometric with each subunit on the enzyme but is highly selective for a peripheral anionic site. Thus, agents such as edrnphonium and N-methylaoridinium which bilnd preferentially to the active center of the enzyme will not dissociate the bound propidium. Bisquaternary ligands such as decamethonium are mutually competitive with both the active center and the peripheral anionic site. The long excitation and emission wavelengths (488/632 nm) of propidium endow it with ideal acceptor properties for energy transfer studies with various donor ligands bound to the active center

Transplantation of Quail Collagen-tailed Acetylcholinesterase Molecules Onto the Frog Neuromuscular Synapse

The highly organized pattern of acetylcholinesterase (AChE) molecules attached to the basal lamina of the neuromuscular junction (NMJ) suggests the existence of specific binding sites for their precise localization. To test this hypothesis we immunoaffinity purified quail globular and collagen-tailed AChE forms and determined their ability to attach to frog NMJs which had been pretreated with high-salt detergent buffers. The NMJs were visualized by labeling acetylcholine receptors (AChRs) with TRITC-α-bungarotoxin and AChE by indirect immunofluorescence; there was excellent correspondence (>97%) between the distribution of frog AChRs and AChE. Binding of the exogenous quail AChE was determined using a speciesspecific monoclonal antibody. When frog neuromuscular junctions were incubated with the globular G4/G2 quail AChE forms, there was no detectable binding above background levels, whereas when similar preparations were incubated with the collagen-tailed A12 AChE form >80% of the frog synaptic sites were also immunolabeled for quail AChE attached. Binding of the A12 quail AChE was blocked by heparin, yet could not be removed with high salt buffer containing detergent once attached. Similar results were obtained using empty myofiber basal lamina sheaths produced by mechanical or freeze-thaw damage. These experiments show that specific binding sites exist for collagen-tailed AChE molecules on the synaptic basal lamina of the vertebrate NMJ and suggest that these binding sites comprise a “molecular parking lot” in which the AChE molecules can be released, retained, and turned over

Prevalence and determinants of asthma in adult male leather tannery workers in Karachi, Pakistan: A cross sectional study

BACKGROUND: This study aimed to estimate the prevalence and to identify some risk factors of adult asthma in male leather tannery workers in Karachi, Pakistan. METHODS: A cross sectional study was conducted from August 2003 to March 2004 on leather tannery workers of Karachi, Pakistan. Data were collected from 641 workers engaged in 95 different tanneries in Korangi industrial area selected as sample of convenience. Face to face interviews were performed using a structured pre-tested questionnaire by trained data collectors. RESULTS: Prevalence of adult asthma was 10.8% (69/641) in this study population. The prevalence of perceived work-related asthma was 5.3% (34/641). Multivariable logistic regression model showed that after taking into account the age effect, the leather tannery worker were more likely to be asthmatic, if they were illiterate (adjusted OR = 2.13, 95% CI: 1.17–3.88), of Pathan ethnicity (adjusted OR = 2.69; 95% CI: 1.35–5.36), ever-smoked (adjusted OR = 2.22, 95% CI: 1.16–4.26), reportedly never used gloves during different tanning tasks (OR = 3.28; 95% CI : 1.72–6.26). Also, the final model showed a significant interaction between perceived allergy and duration of work. Those who perceived to have allergy were more likely to have asthma if their duration of work was 8 years (adjusted OR = 2.26; 95% CI: 1.19 – 4.29) and this relationship was even stronger if duration was 13 years (adjusted OR = 3.67; 95% CI: 1.98–6.79). CONCLUSION: Prevalence of asthma in leather tannery workers appears to be high and is associated with educational status, ethnicity, smoking, glove use, perceived to have allergy and duration of work

Laminin γ2 fragments are increased in the circulation of patients with early phase acute lung injury

Katayama, M., Ishizaka, A., Sakamoto, M. et al. Intensive Care Med (2010) 36: 479. https://doi.org/10.1007/s00134-009-1719-

Using the ecology model to describe the impact of asthma on patterns of health care

BACKGROUND: Asthma changes both the volume and patterns of healthcare of affected people. Most studies of asthma health care utilization have been done in selected insured populations or in a single site such as the emergency department. Asthma is an ambulatory sensitive care condition making it important to understand the relationship between care in all sites across the health service spectrum. Asthma is also more common in people with fewer economic resources making it important to include people across all types of insurance and no insurance categories. The ecology of medical care model may provide a useful framework to describe the use of health services in people with asthma compared to those without asthma and identify subgroups with apparent gaps in care. METHODS: This is a case-control study using the 1999 U.S. Medical Expenditure Panel Survey. Cases are school-aged children (6 to 17 years) and young adults (18 to 44 years) with self-reported asthma. Controls are from the same age groups who have no self-reported asthma. Descriptive analyses and risk ratios are placed within the ecology of medical care model and used to describe and compare the healthcare contact of cases and controls across multiple settings. RESULTS: In 1999, the presence of asthma significantly increased the likelihood of an ambulatory care visit by 20 to 30% and more than doubled the likelihood of making one or more visits to the emergency department (ED). Yet, 18.8% of children and 14.5% of adults with asthma (over a million Americans) had no ambulatory care visits for asthma. About one in 20 to 35 people with asthma (5.2% of children and 3.6% of adults) were seen in the ED or hospital but had no prior or follow-up ambulatory care visits. These Americans were more likely to be uninsured, have no usual source of care and live in metropolitan areas. CONCLUSION: The ecology model confirmed that having asthma changes the likelihood and pattern of care for Americans. More importantly, the ecology model identified a subgroup with asthma who sought only emergent or hospital services

The Role of Elytra in the Movement of Water Over the Surface of Halosydna brevisetosa (Polychaeta: Polynoidae)

In intact worms ciliary tracts on the parapodial lobes and dorsal body surface bring in a flow of water laterally between parapodial lobes and carry it posteriorly along the body dorsolaterally below each row of elytra. The elytrae are not ciliated and exhibit no fanning or pumping motions, but are so shaped as to direct the incoming lateral flow posteriorly, and to contain and direct the posterior flow over the more or less corrugated dorsolateral body surfaces. They also permit the currents to operate effectively when worms are wedged into the secluded crevices and situations which they tend to seek during daylight hours. Thin areas of the body wall are provided with an external flow of water moving in one direction and an internal flow of coelomic fluid moving the opposite direction, and are presumed to function in respiratory gas exchange

Risk factors for asthma prevalence and chronic respiratory illnesses among residents of different neighbourhoods in Buffalo, New York

Study objective: The aim of this study is to identify risk factors for asthma prevalence and chronic respiratory illnesses in Buffalo's neighbourhoods after previous studies reported increased levels of asthma among residents on Buffalo's west side. Design: Cross sectional surveys. Setting: Buffalo neighbourhoods along a US-Canada border crossing point. Subjects: A systematic random survey of 82% of the 2000 targeted households was conducted between January and August 2002. Main results: A multivariate logistic regression model shows that the risk of persons with asthma and chronic respiratory illnesses is significantly (p⩽0.05) high among children and young adults living in Buffalo's west side, newer housing units, and of Latino ethnicity. In a separate analysis of the nine risk factors, it was observed that location, gender, age, and race were significant risk factors even after adjusting for age of housing, pets, moulds, animal trigger, and smoking. Conclusions: These findings confirm the hypothesis that a considerable risk of asthma and chronic respiratory illnesses exists particularly among Buffalo's west side residents. Further evaluation of these risk factors is warranted to determine the severity of asthma and the reasons for such a significant disease burden