Search

Answers several questions related to nursing. Legal aspects of combining medical patients with psychiatric patients in the same room; Liability of an intern for performing procedures to a dead body; Supervision of nurses.

Li 5 V 3 O 8 , a lithiation product derived from the LiV 3 O 8 cathode, has emerged as a promising intercalation-type anode material, boasting a theoretical capacity of 256 mA h g -1 . Through a comprehensive combination of experimental and theoretical approaches, we demonstrate its capability to intercalate a substantial amount of Li + at extremely high rates. Experimental findings reveal that Li 5 V 3 O 8 exhibits outstanding high-rate capability (with a specific capacity of 152 mA h g -1 , 60% of the theoretical capacity at 40 C) and exceptional cyclability (with a capacity retention of 80% after 11,000 cycles at 20 C). The structural changes in Li 5 V 3 O 8 during the lithiation/delithiation cycles are subtle and reversible. First-principles calculations highlight a knock-off mechanism in Li + diffusion within Li 5 V 3 O 8 , with an estimated energy barrier ranging from 0.16 to 0.38 eV, considerably lower than that of a direct hopping mechanism (0.62-1.44 eV). These ultrafast ion diffusion properties are attributed to interlock interactions among interstitial tetrahedral Li + and neighboring octahedral lattice Li + , facilitating long-distance and chain-like Li + diffusion. This study not only introduces an influential vanadium-based anode material with practical implications for fast-charging lithium-ion batteries but also provides fundamental insights into solid state Li + diffusion kinetics.

Antibiotic resistance is an urgent threat to global health, with the decreasing efficacy of conventional drugs underscoring the urgency for innovative therapeutic strategies. Antimicrobial peptides present as promising alternatives to conventional antibiotics. Gramicidin S is one such naturally occurring antimicrobial peptide that is effective against Staphylococcus aureus , with a minimum inhibitory concentration (MIC) of 4 μg/mL (3.6 μM). Despite this potent activity, its significant hemolytic toxicity restricts its clinical use to topical applications. Herein, we present rational modifications to the key β-strand and β-turn regions of gramicidin S to concurrently mitigate hemolytic effects, while maintaining potency. Critically, peptide 9 displayed negligible hemolytic toxicity, while possessing significant antibacterial potency against a panel of methicillin-sensitive and methicillin-resistant S. aureus clinical isolates (MIC of 8 μg/mL, 7.2 μM). Given the substantial antibacterial activity and near absence of cytotoxicity, 9 presents as a potential candidate for systemic administration in the treatment of S. aureus bacteremia/sepsis.

A novel strategy to treat Staphylococcus aureus (S. aureus) skin infections is presented, where UV light is used to facilitate concomitant light-controlled activation and delivery of an antimicrobial therapeutic agent. Specifically, a new photoswitchable gramicidin S analogue was immobilized onto a polymeric wearable patch via a photocleavable linker that undergoes photolysis at the same wavelength of light required for activation of the peptide. Unlike toxic gramicidin S, the liberated active photoswitchable peptide exhibits antimicrobial activity against S. aureus while being ostensibly non-haemolytic to red blood cells. Moreover, irradiation with visible light switches off the antimicrobial properties of the peptide within seconds, presenting an ideal strategy to regulate antibiotic activity for localized bacterial infections with the potential to mitigate resistance., (© 2023 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

The deposition of α-synuclein (αS) aggregates in the gut and the brain is ever present in cases of Parkinson's disease. While the central non-amyloidogenic-component (NAC) region of αS plays a critical role in fibrilization, recent studies have identified a specific sequence from within the N-terminal region (NTR, residues 36-42) as a key modulator of αS fibrilization. Due to the lack of effective therapeutics which specifically target αS aggregates, we have developed a strategy to prevent the aggregation and subsequent toxicity attributed to αS fibrilization utilizing NTR targeting peptides. In this study, L- and D-isoforms of a hexa- (VAQKTV-Aib, 77-82 NAC) and heptapeptide (GVLYVGS-Aib, 36-42 NTR) containing a self-recognition component unique to αS, as well as a C-terminal disruption element, were synthesized to target primary sequence regions of αS that modulate fibrilization. The D-peptide that targets the NTR (NTR-TP-D) was shown by ThT fluorescence assays and TEM to be the most effective at preventing fibril formation and elongation, as well as increasing the abundance of soluble monomeric αS. In addition, NTR-TP-D alters the conformation of destabilised monomers into a less aggregation-prone state and reduces the hydrophobicity of αS fibrils via fibril remodelling. Furthermore, both NTR-TP isoforms alleviate the cytotoxic effects of αS aggregates in both Neuro-2a and Caco-2 cells. Together, this study highlights how targeting the NTR of αS using D-isoform peptide inhibitors may effectively combat the deleterious effects of αS fibrilization and paves the way for future drug design to utilise such an approach to treat Parkinson's disease., (Copyright © 2022 Elsevier B.V. All rights reserved.)

The fabrication of solid-state single-molecule switches with high on-off conductance ratios has been proposed to advance conventional technology in areas such as molecular electronics. Herein, we employed the scanning tunneling microscope break junction (STM-BJ) technique to modulate conductance in single-molecule junctions using mechanically induced stretching. Compound 1a possesses two dihydrobenzothiophene (DHBT) anchoring groups at the opposite ends linked with rigid alkyne side arms to form a gold-molecule-gold junction, while 1b contains 4-pyridine-anchoring groups. The incorporation of ferrocene into the backbone of each compound allows rotational freedom to the cyclopentadienyl (Cp) rings to give two distinct conductance states (high and low) for each. Various control experiments and suspended junction compression/retraction measurements indicate that these high- and low-conductance plateaus are the results of conformational changes within the junctions (extended and folded states) brought about by mechanically induced stretching. A high-low switching factor of 42 was achieved for 1a , whereas an exceptional conductance ratio in excess of 2 orders of magnitude (205) was observed for 1b . To the best of our knowledge, this is the highest experimental on-off conductance switching ratio for a single-molecule junction exploiting the mechanically induced STM-BJ method. Computational studies indicated that the two disparate conductance states observed for 1a and 1b result from mechanically induced conformational changes due to an interplay between conductance and the dihedral angles associated with the electrode-molecule interfaces. Our study reveals the structure-function relationship that determines conductance in such flexible and dynamic systems and promotes the development of a single-molecule variable resistor with high on-off switching factors.

The majority of the protein structures have been elucidated under equilibrium conditions. The aim herein is to provide a better understanding of the dynamic behavior inherent to proteins by fabricating a label-free nanodevice comprising a single-peptide junction to measure real-time conductance, from which their structural dynamic behavior can be inferred. This device contains an azobenzene photoswitch for interconversion between a well-defined cis, and disordered trans isomer. Real-time conductance measurements revealed three distinct states for each isomer, with molecular dynamics simulations showing each state corresponds to a specific range of hydrogen bond lengths within the cis isomer, and specific dihedral angles in the trans isomer. These insights into the structural dynamic behavior of peptides may rationally extend to proteins. Also demonstrated is the capacity to modulate conductance which advances the design and development of bioinspired electronic nanodevices., (© 2020 Wiley-VCH GmbH.)

Three photoswitchable tetrapeptides, based on a known synthetic antibacterial, were designed and synthesized to determine activity against Staphylococcus aureus. Each peptide contains an azobenzene photoswitch incorporated into either the N-terminal side chain (1), C-terminal side chain (2), or the C-terminus (3) to allow reversible switching between cis- and trans-enriched photostationary states. Biological assays revealed that the C-terminus azobenzene (3) possessed the most potent antibacterial activity, with an MIC of 1 μg/mL. In this study, net positive charge, hydrophobicity, position of the azobenzene, secondary structure, and amphiphilicity were all found to contribute to antibacterial activity, with each of these factors likely facilitating the peptide to disrupt the negatively charged bacterial lipid membrane. Hence, these short photoswitchable antibacterial tetrapeptides provide insights for the future design and synthesis of antibiotics targeting S. aureus., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Understanding and controlling charge transport across multiple parallel molecules are fundamental to the creation of innovative functional electronic components, as future molecular devices will likely be multimolecular. The smallest possible molecular ensemble to address this challenge is a dual-molecule junction device, which has potential to unravel the effects of intermolecular crosstalk on electronic transport at the molecular level that cannot be elucidated using either conventional single-molecule or self-assembled monolayer (SAM) techniques. Herein, we demonstrate the fabrication of a scanning tunneling microscopy (STM) dual-molecule junction device, which utilizes noncovalent interactions and allows for direct comparison to the conventional STM single-molecule device. STM-break junction (BJ) measurements reveal a decrease in conductance of 10% per molecule from the dual-molecule to the single-molecule junction device. Quantum transport simulations indicate that this decrease is attributable to intermolecular crosstalk (i.e., intermolecular π-π interactions), with possible contributions from substrate-mediated coupling (i.e., molecule-electrode). This study provides the first experimental evidence to interpret intermolecular crosstalk in electronic transport at the STM-BJ level and translates the experimental observations into meaningful molecular information to enhance our fundamental knowledge of this subject matter. This approach is pertinent to the design and development of future multimolecular electronic components and also to other dual-molecular systems where such crosstalk is mediated by various noncovalent intermolecular interactions (e.g., electrostatic and hydrogen bonding).

Amyloid beta peptide (Aβ42) aggregation in the brain is thought to be responsible for the onset of Alzheimer's disease, an insidious condition without an effective treatment or cure. Hence, a strategy to prevent aggregation and subsequent toxicity is crucial. Bio-inspired peptide-based molecules are ideal candidates for the inhibition of Aβ42 aggregation, and are currently deemed to be a promising option for drug design. In this study, a hexapeptide containing a self-recognition component unique to Aβ42 was designed to mimic the β-strand hydrophobic core region of the Aβ peptide. The peptide is comprised exclusively of D-amino acids to enhance specificity towards Aβ42, in conjunction with a C-terminal disruption element to block the recruitment of Aβ42 monomers on to fibrils. The peptide was rationally designed to exploit the synergy between the recognition and disruption components, and incorporates features such as hydrophobicity, β-sheet propensity, and charge, that all play a critical role in the aggregation process. Fluorescence assays, native ion-mobility mass spectrometry (IM-MS) and cell viability assays were used to demonstrate that the peptide interacts with Aβ42 monomers and oligomers with high specificity, leading to almost complete inhibition of fibril formation, with essentially no cytotoxic effects. These data define the peptide-based inhibitor as a potentially potent anti-amyloid drug candidate for this hitherto incurable disease., (© 2020 The Author(s).)

A prodrug based on a known antibacterial compound is reported to target Staphylococcus aureus and Escherichia coli under reductive conditions. The prodrug was prepared by masking the N-terminus and side chain amines of a component lysine residue as 4-nitrobenzyl carbamates. Activation to liberate the antibacterial was demonstrated on treatment with a model reductant, tin(II) chloride. The bioactivity of 1 was confirmed in antibacterial susceptibility assays whereas prodrug 2 was inactive., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Metalloproteins are crucial to many biological processes, such as photosynthesis, respiration, and efficient electron transport. Zinc is the most common transition metal found in proteins and is critical for structure, function and stability, however the effects from the electronic properties of a bound zinc ion on electron transfer are not clearly defined. Here, a series of β-strand and 310-helical peptides, capable of binding Zn2+via suitably positioned His residues, was synthesized and their ability to undergo electron transfer in the presence and absence of Zn2+ studied by electrochemical and computational means. The β-strand peptide was shown to be conformationally pre-organized, with this geometry maintained on complexation with zinc. Electrochemical studies show a significant increase in charge transport, following binding of the zinc ion to the β-strand peptide. In contrast, complexation of zinc to the helical peptide disrupts the intramolecular hydrogen bonding network known to facilitate electron transfer and leads to a loss of secondary structure, resulting in a decrease in charge transfer. These experimental and computational studies reveal an interplay, which demonstrates that bound zinc enhances charge transfer by changing the electronic properties of the peptide, and not simply by influencing secondary structure.

The primary sequence and secondary structure of a peptide are crucial to charge migration, not only in solution (electron transfer, ET), but also in the solid-state (electron transport, ETp). Hence, understanding the charge migration mechanisms is fundamental to the development of biomolecular devices and sensors. We report studies on four Aib-containing helical peptide analogues: two acyclic linear peptides with one and two electron-rich alkene-based side chains, respectively, and two peptides that are further rigidified into a macrocycle by a side bridge constraint, containing one or no alkene. ETp was investigated across Au/peptide/Au junctions, between 80 and 340 K in combination with the molecular dynamic (MD) simulations. The results reveal that the helical structure of the peptide and electron-rich side chain both facilitate the ETp. As temperature increases, the loss of helical structure, change of monolayer tilt angle, and increase of thermally activated fluctuations affect the conductance of peptides. Specifically, room temperature conductance across the peptide monolayers correlates well with previously observed ET rate constants, where an interplay between backbone rigidity and electron-rich side chains was revealed. Our findings provide new means to manipulate electronic transport across solid-state peptide junctions.

Gramicidin S is a naturally occurring antimicrobial cyclic peptide. Herein, we present a series of cyclic peptides based on gramicidin S that contain an azobenzene photoswitch to reversibly control secondary structure and, hence, antimicrobial activity. 1 H NMR spectroscopy and density functional theory calculations revealed a β-sheet/β-turn secondary structure for the cis configuration of each peptide, and an ill-defined conformation for all associated trans structures. The cis-enriched and trans-enriched photostationary states (PSSs) for peptides 1-3 were assayed against Staphylococcus aureus to reveal a clear relationship between well-defined secondary structure, amphiphilicity and optimal antimicrobial activity. Most notably, peptides 2 a and 2 b exhibited a fourfold difference in antimicrobial activity in the cis-enriched PSS over the trans-enriched equivalent. This photopharmacological approach allows antimicrobial activity to be regulated through photochemical control of the azobenzene photoswitch, thereby opening new avenues in the design and synthesis of future antibiotics., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Neuronal nitric oxide synthase (nNOS) is an enzyme responsible for catalyzing the production of the crucial cellular signalling molecule, nitric oxide (NO), through its interaction with the PDZ domain of α-syntrophin protein. In this study, a novel light-driven photoswitchable peptide-based biosensor, modelled on the nNOS β-finger, is used to detect and control its interaction with α-syntrophin. An azobenzene photoswitch incorporated into the peptide backbone allows reversible switching between a trans photostationary state devoid of secondary structure, and a cis photostationary state possessing a well-defined antiparallel β-strand geometry, as revealed by molecular modelling. Electrochemical impedance spectroscopy (EIS) is used to successfully detect the interaction between the gold electrode bound peptide in its cis photostationary state and a wide range of concentrations of α-syntrophin protein, highlighting both the qualitative and quantitative properties of the sensor. Furthermore, EIS demonstrates that the probe in its random trans photostationary state does not bind to the target protein. The effectiveness of the biosensor is further endorsed by the high thermal stability of the photostationary state of the cis-isomer, and the ability to actively control biomolecular interactions using light. This approach allows detection and control of binding to yield a regenerable on-off biosensor., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Molecular electronics is at the forefront of interdisciplinary research, offering a significant extension of the capabilities of conventional silicon-based technology as well as providing a possible stand-alone alternative. Bio-inspired molecular electronics is a particularly intriguing paradigm, as charge transfer in proteins/peptides, for example, plays a critical role in the energy storage and conversion processes for all living organisms. However, the structure and conformation of even the simplest protein is extremely complex, and therefore, synthetic model peptides comprising well-defined geometry and predetermined functionality are ideal platforms to mimic nature for the elucidation of fundamental biological processes while also enhancing the design and development of single-peptide electronic components. In this Account, we first present intramolecular electron transfer within two synthetic peptides, one with a well-defined helical conformation and the other with a random geometry, using electrochemical techniques and computational simulations. This study reveals two definitive electron transfer pathways (mechanisms), the natures of which are dependent on secondary structure. Following on from this, electron transfer within a series of well-defined helical peptides, constrained by either Huisgen cycloaddition, ring-closing metathesis, or a lactam bridge, was determined. The electrochemical results indicate that each constrained peptide, in contrast to a linear counterpart, exhibits a remarkable shift of the formal potential to the positive (>460 mV) and a significant reduction of the electron transfer rate constant (up to 15-fold), which represent two distinct electronic "on/off" states. High-level calculations demonstrate that the additional backbone rigidity provided by the side-bridge constraints leads to an increased reorganization energy barrier, which impedes the vibrational fluctuations necessary for efficient intramolecular electron transfer through the peptide backbone. Further calculations reveal a clear mechanistic transition from hopping to superexchange (tunneling) stemming from side-bridge gating. We then extended our research to fine-tuning of the electronic properties of peptides through both structural and chemical manipulation, to reveal an interplay between electron-rich side chains and backbone rigidity on electron transfer. Further to this, we explored the possibility that the side-bridge constraints present in our synthetic peptides provide an additional electronic transport pathway, which led to the discovery of two distinct forms of quantum interferometer. The effects of destructive quantum interference appear essentially through both the backbone and an alternative tunneling pathway provided by the side bridge in the constrained β-strand peptide, as evidenced by a correlation between electrochemical measurements and conductance simulations for both linear and constrained β-strand peptides. In contrast, an interplay between quantum interference effects and vibrational fluctuations is revealed in the linear and constrained 3 10 -helical peptides. Collectively, these exciting findings augment our fundamental knowledge of charge transfer dynamics and kinetics in peptides and also open up new avenues to design and develop functional bio-inspired electronic devices, such as on/off switches and quantum interferometers, for practical applications in molecular electronics.

Understanding the electronic properties of single peptides is not only of fundamental importance, but it is also paramount to the realization of peptide-based molecular electronic components. Electrochemical and theoretical studies are reported on two β-strand-based peptides, one with its backbone constrained with a triazole-containing tether introduced by Huisgen cycloaddition (peptide 1) and the other a direct linear analogue (peptide 2). Density functional theory (DFT) and non-equilibrium Green's function were used to investigate conductance in molecular junctions containing peptides 3 and 4 (analogues of 1 and 2). Although the peptides share a common β-strand conformation, they display vastly different electronic transport properties due to the presence (or absence) of the side-bridge constraint and the associated effect on backbone rigidity. These studies reveal that the electron transfer rate constants of 1 and 2, and the conductance calculated for 3 and 4, differ by approximately one order of magnitude, thus providing two distinctly different conductance states and what is essentially a molecular switch. A definitive correlation of electrochemical measurements and molecular junction conductance simulations is demonstrated using two different charge transfer techniques. This study furthers our understanding of the electronic properties of peptides at the molecular level, which provides an opportunity to fine-tune their molecular orbital energies through suitable structural manipulation., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Electrochemical studies are reported on a series of peptides constrained into either a 310-helix (1-6) or β-strand (7-9) conformation, with variable numbers of electron rich alkene containing side chains. Peptides (1 and 2) and (7 and 8) are further constrained into these geometries with a suitable side chain tether introduced by ring closing metathesis (RCM). Peptides 1, 4 and 5, each containing a single alkene side chain reveal a direct link between backbone rigidity and electron transfer, in isolation from any effects due to the electronic properties of the electron rich side-chains. Further studies on the linear peptides 3-6 confirm the ability of the alkene to facilitate electron transfer through the peptide. A comparison of the electrochemical data for the unsaturated tethered peptides (1 and 7) and saturated tethered peptides (2 and 8) reveals an interplay between backbone rigidity and effects arising from the electron rich alkene side-chains on electron transfer. Theoretical calculations on β-strand models analogous to 7, 8 and 9 provide further insights into the relative roles of backbone rigidity and electron rich side-chains on intramolecular electron transfer. Furthermore, electron population analysis confirms the role of the alkene as a "stepping stone" for electron transfer. These findings provide a new approach for fine-tuning the electronic properties of peptides by controlling backbone rigidity, and through the inclusion of electron rich side-chains. This allows for manipulation of energy barriers and hence conductance in peptides, a crucial step in the design and fabrication of molecular-based electronic devices.

Two helical peptides, one constrained by a covalent side-chain staple, exhibit vastly different electronic properties despite adopting essentially the same backbone conformation. High level calculations confirm that these differences are due to the additional backbone rigidity imparted by the macrocyclic constraint.

A random sample of subjects over 65 years of age who had replied to a postal questionnaire on respiratory symptoms was asked to attend for lung function studies and, if fit, an inhaled methacholine bronchial challenge. Of 283 subjects, 180 (63.6%) agreed to attend. Most (98%) subjects performed reproducible spirometry, with no evidence of fatigue on repeated testing. However, 20 subjects were found to be unsuitable for challenge (forced expiratory volume in 1 s, (FEV1) < 1 litre or unable to perform spirometry reproducibly). The dose of methacholine producing a 20% fall in FEV1 was termed the PD20. A positive challenge with PD20 < 6.13 mumol methacholine was found in 69 of 160 (43%) subjects studied, with highly reactive airways (PD20 < 1.0 mumol methacholine) in 19 of 160 (12%). Bronchial hyperreactivity, which is closely associated with clinical asthma, was found to be far more common amongst the elderly than previously recognised. Low initial FEV1 (1-1.5 litres) predisposed to both a positive challenge (p < 0.01) and also to highly reactive airways (p < 0.01), generally associated with respiratory symptoms. Subjects with low (1-1.5 litres) baseline FEV1 were five times more likely to have highly reactive airways than those with FEV1 > 1.5 litres, confirming a relationship between baseline airway calibre and bronchial reactivity. Early detection of subjects with low FEV1, who are therefore more likely to have increased airway reactivity, may help to reduce respiratory morbidity in the elderly with considerable benefit both to patients and to the Health Service.

This study was carried out to estimate the prevalence of respiratory symptoms among people aged 65 years and older and assess the value of a postal survey in obtaining this information. A questionnaire was sent to 2011 subjects (957 men) drawn by age-stratified random sampling from the age-sex registers of four New Forest group practices (1:3.3 sample). A total of 1803 replied, a 96.2% response after excluding 136 who had died or moved from the area. The accuracy of replies was verified for 355 (20%) randomly selected subjects. Forty per cent had no respiratory symptoms. Exertional breathlessness was common (38%), increasing in prevalence with age but not with smoking history, and was the only symptom reported by 10% of subjects. Only 14.2% were current smokers; more of the subjects aged 85 years and over were lifelong non-smokers. Two hundred and ninety-six (16.4%) had chronic bronchitis, which was more common among smokers; 151 (8.4%) gave a history of asthma, of whom half (76) had active asthma, which was slightly less common among the very elderly subjects. Only 489 (27.1%) of subjects had seen their doctors with chest symptoms during the preceding 2 years.

Regional residual volume to total lung capacity (RVr/TLCr) was measured with xenon 133 before and after methacholine challenge in 26 nonsmoking subjects (mean age 34 years). Eleven were normal control subjects and 15 were patients referred for methacholine challenge because of previous asthma-like symptoms. All had normal pulmonary function and normal RVr/TLCr distribution. Following methacholine challenge, RVr/TLCr increased in two control subjects and ten patients who also had decreases in FEV1 of greater than 20 percent. The RVr/TLCr changes were patchy, suggesting that the degree of bronchospasm varied between individual lung regions. The other 14 subjects did not have a 20 percent decrease in FEV1, but two controls and four patients had generalized increases in RVr/TLCr, while seven controls and one patient had no significant changes in RVr/TLCr. In all subjects, FEV1 and RVr/TLCr returned to the baseline level after salbutamol administration. The results indicate that methacholine can cause localized or diffuse effects on lung emptying and that bronchodilator completely reverses the bronchoconstriction induced by methacholine.

Retrospective review of 251 bronchial submucosal needle aspirations obtained from 171 patients with unsuspected pulmonary malignancy showed that adequate cytologic material was obtained in 87.6% of the aspirations. Eighty-one patients were found to have primary bronchogenic carcinomas (with a visible endobronchial tumor in 39), and 21 had secondary pulmonary metastases. The overall diagnostic accuracy of bronchial submucosal aspiration was 81%, with only four definite false-negative and no false-positive results. The diagnostic accuracy was 82% for bronchial brushing, 71% for forceps biopsy, 67% for postbronchoscopy sputum cytology and 46% for bronchial washing. The major advantage of the submucosal aspiration technique was in evaluating mural mucosal lesions, especially those covered with intact mucosa, that were not readily accessible to forceps biopsy or successful brush sampling. Negative results from a needle aspiration must be interpreted with caution because of the small area a single sample represents. Multiple sequential submucosal aspirations may be helpful in assessing the resectability of bronchial neoplasms. No complications have been encountered with this technique.