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Biomedical subjects

A McLaughlin

Publications and source records attributed to A McLaughlin.

At least 19 recordsLinked to original sources
PubMed2003

New method to evaluate the practice of positive pressure ventilation in intensive care units.

BACKGROUND: There is good evidence to support the use of a "protective" ventilation strategy, using small tidal volumes and inspiratory pressures, in patients with acute respiratory distress syndrome. Many general intensive care units in the UK are being slow to adopt this approach and we therefore set out to devise a method to audit ventilation and possibly influence practice in these units. METHODS: Using variables that are routinely documented by intensive care nurses, we assessed the relationship between ventilator settings and arterial blood gas values on 30 consecutive ventilated patients admitted to intensive care units at both a teaching and a district hospital. Data were recorded twice daily and the proportions of data points where there was unnecessary hyperventilation were recorded at each centre. RESULTS: The initial audit results showed clear differences in practice between the teaching hospital and the district hospital. After an intensive education programme, during which an active role for nursing staff in ventilator management was encouraged, supported by simple protocols, practice in the district hospital was re-audited and found to closely mirror that in the teaching centre. CONCLUSIONS: To assist progress towards the use of a "protective" ventilation strategy in intensive care units in the UK, we devised a simple, robust audit method. We have shown how this method can give a more uniform practice of ventilation in critical care units, with the introduction of nurse-run protocols.

Critical Care↗
PubMed2001

Direct optometrist referral of cataract patients into a pilot 'one-stop' cataract surgery facility.

OBJECTIVES: To determine the feasibility of a) direct optometrist referral of patients with cataract, and b) combined assessment with same day cataract surgery ('one stop' cataract surgery). METHODS: Evaluation of 169 patients referred directly by optometrists into a pilot 'one stop' cataract surgery facility. RESULTS: Of 169 referrals, 160 patients (94.7%) were given confirmed appointments for the 'one stop' cataract service and 9 patients (5.3%) were appointed conventionally. Of 160 patients attending the 'one stop' cataract service, 154 patients (96.3%) underwent cataract surgery at the same visit, in 4 patients (2.5%) cataract surgery was indicated but deferred and in 2 patients (1.3%) cataract surgery was not indicated. The referral was supplemented with information regarding the patient's medical history forwarded by the general practitioner for 3 patients (1.8%). There were no systemic or sight-threatening complications. 151 patients (98.1%) achieved a visual acuity of 6/12 or better at a mean of 31 days post-operatively. CONCLUSION: Optometrists can accurately predict the need for cataract surgery and refer directly into a pilot 'one stop' cataract surgery facility, without the need for general practitioner involvement. 'One stop' cataract surgery is feasible; benefits to the patient include the abolition of the need to visit the general practitioner for consultation and referral, and the hospital for pre-assessment.

Ambulatory Surgical Procedures↗
PubMed2000

Web reports.

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Critical Care↗
PubMed1999

Scintigraphic patterns of injury in amateur weight lifters.

PURPOSE: Weight lifting is now a standard part of training in most sports. An increasing number of amateur athletes are doing strength training, mostly in unsupervised situations. A series of injuries in amateur weight lifters was analyzed by bone scintigraphy, with the aim of depicting specific patterns that would accurately identify the primary lesions. METHODS: Twelve patients (10 men and 2 women) were studied whose ages ranged from 18 to 35 years. Patients were referred for bone scintigraphy with clinical diagnoses based on history, physical examination, and appropriate radiologic investigations. Diagnoses were confirmed by surgery, arthroscopy, arthrography, local steroid injection, and outcome. RESULTS: Most of the injuries were in athletes undertaking free-weight training. Most injuries were in the upper limbs, particularly around the shoulder. Scintigraphic patterns of supraspinatus and bicipital tendons and also rotator cuff lesions were identified. Clavicular osteolysis, avulsion injuries, muscle damage, and vertebral lesions were also noted. Several abnormalities revealed by scintigraphy were clinically unsuspected. CONCLUSIONS: Scintigraphic manifestations of several injuries, particularly around the shoulder, have a specific pattern. Recognition of these patterns can enhance the performance of bone scintigraphy. Scintigraphy also has the potential to detect clinically unsuspected disease.

Acromioclavicular Joint↗
PubMed1999

MR perfusion imaging.

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Cerebrovascular Circulation↗
PubMed1997

The immunomodulatory actions of E-type prostaglandins.

Prostaglandins (PGs) have been recognised as modulators of immune responses. This has been proved by both in vitro studies and from observations in animals and humans. Administration of prostaglandins for therapeutic purposes, however, has been hampered by their limited bioavailability and their pleiotropic effects, with resultant toxicological profile. Despite this, some success has been demonstrated in the clinic for the control of graft rejection, especially when used as part of a broader immunosuppressant regimen. Full realisation of the therapeutic potential of prostaglandins will depend on a better understanding of their mechanism of action at the cellular level. Recently, it has been appreciated that prostaglandins do not merely inhibit T-cell function, but appear to modulate the profile of lymphocyte sub-populations through regulation of cytokine synthesis and release. Recent efforts have also begun to focus on identifying prostaglandin receptor subtypes important for immune regulation and offer a means, together with targeted delivery, of utilising the immunosuppressant/anti-inflammatory effects of E-type prostaglandins in a safe and effective manner.

Journal Article↗
PubMed1996

A technique for single-channel MR brain tissue segmentation: application to a pediatric sample.

A segmentation method is presented for gray matter, white matter, and cerebrospinal fluid (CSF) in thin-sliced single-channel brain magnetic resonance (MR) scans. The method is based on probabilistic modeling of intensity distributions and on a region growing technique. Interrater and intrarater reliabilities for the method were high, and comparison with phantom studies and hand-traced results from an experienced rater indicated good validity. The method was designed to account for spatially dependent image intensity inhomogeneities. Segmentation of MR brain scans of 105 (56 male and 49 female) healthy children and adolescents showed that although the total brain volume was stable over age 4-18, white matter increased and gray matter decreased significantly. There were no sex differences in total gray and white matter growth after correction for total brain volume. White matter volume increased the most in superior and posterior regions and laterality effects were seen in hemisphere tissue volumes. These findings are consistent with other reports, and further validate the segmentation technique.

Adolescent↗
PubMed1996

Noise levels in a cardiac surgical intensive care unit: a preliminary study conducted in secret.

Noise in hospitals frequently exceeds recommended levels and has detrimental psychological and physiological effects on patients and staff. The aim of this study was to record the noise levels within the cardiac surgical intensive care unit (CSICU) environment in secret. The device used was a CEL Instruments environmental noise meter concealed in a dummy box featuring temperature and humidity digital displays. It allowed greater than 16 hours recording time at a 1-minute resolution. The 24-hour period was covered by overlapping recordings. The data collected were downloaded onto a personal computer for analysis. The maximum sound level recorded was 100.9 decibel level (dBA), 1 min Lmax (the maximum sound level occurring in a 1-min period). The minimum sound level was 61.3 dBA 1 min Lmax. The continuous background noise was at its lowest at 57.5 dBA 1 min equivalent continuous sound pressure levels (Leq) and at its peak 77.3 dBA 1 min Leq. Noise in the CSICU was above the recommended levels for patients and staff well-being. Future studies will be designed to establish a correlation between sound levels and events.

Cardiac Surgical Procedures↗
PubMed1995

The antiinflammatory activity of topically applied novel calcium-channel antagonists.

The antiinflammatory activities of two novel calcium-channel antagonists, AGN 190742 and AGN 190744, were evaluated in murine models of cutaneous inflammation. These 2(5H)-furanone ring compounds block both depolarization-dependent Ca2+ entry and receptor-mediated responses in GH3 cells. Topical application of AGN 190742 or AGN 190744 inhibits neutrophil infiltration and epidermal hyperplasia induced by repeated treatment of mouse skin with phorbol ester. AGN 190744 also is active in an arachidonic acid model of acute inflammation. These data suggest that topical application of calcium-channel antagonists can inhibit cutaneous inflammatory responses and that AGN 190742 and/or AGN 190744 may serve as useful pharmacological probes for examining these responses in vivo.

Administration, Cutaneous↗
PubMed1995

An EP receptor with a novel pharmacological profile in the T-cell line Jurkat.

1. Comparison of the rank order of potency of the natural prostanoids prostaglandin E2 (PGE2), PGD2, PGF2 alpha and carbaprostacyclin in stimulating cyclic AMP in Jurkat cells is consistent with the presence of an EP receptor. 2. Lack of responsiveness to the EP1/EP3 selective agonist, sulprostone, and the EP2 agonists, butaprost and AH 13205, indicates that this receptor is not of the EP1, EP2 or EP3 subtypes. 3. Inhibition of PGE2-stimulated cyclic AMP by the EP4 antagonist, AH 23848 is non-competitive, unlike the competitive antagonism reported in the pig saphenous vein EP4 preparation. Furthermore, 16,16-dimethyl PGE2 is 100 fold less potent than PGE2 in Jurkat cells, while these agonists are equipotent in the rabbit jugular vein purported EP4 preparation. In addition, 1-OH PGE1, which also is active in the rabbit jugular vein preparation, is inactive in Jurkat cells at concentrations up to 1 x 10(-4) M. These data are not wholly consistent with any adenylate cyclase coupled EP receptor described to date. 4. It is postulated that an EP receptor, positively coupled to adenylate cyclase, with a unique pharmacological profile is present in Jurkat cells.

Adenylyl Cyclases↗
PubMed1988

Adsorption of cations to phosphatidylinositol 4,5-bisphosphate.

We investigated the binding of physiologically and pharmacologically relevant ions to the phosphoinositides by making 31P NMR, electrophoretic mobility, surface potential, and calcium activity measurements. We studied the binding of protons to phosphatidylinositol 4,5-bisphosphate (PIP2) by measuring the effect of pH on the chemical shifts of the 31P NMR signals from the two monoester phosphate groups of PIP2. We studied the binding of potassium, calcium, magnesium, spermine, and gentamicin ions to the phosphoinositides by measuring the effect of these cations on the electrophoretic mobility of multilamellar vesicles formed from mixtures of phosphatidylcholine (PC) and either phosphatidylinositol, phosphatidylinositol 4-phosphate, or PIP2; the adsorption of these cations depends on the surface potential of the membrane and can be described qualitatively by combining the Gouy-Chapman theory with Langmuir adsorption isotherms. Monovalent anionic phospholipids, such as phosphatidylserine and phosphatidylinositol, produce a negative electrostatic potential at the cytoplasmic surface of plasma membranes of erythrocytes, platelets, and other cells. When the electrostatic potential at the surface of a PC/PIP2 bilayer membrane is -30 mV and the aqueous phase contains 0.1 M KCl at pH 7.0, PIP2 binds about one hydrogen and one potassium ion and has a net charge of about -3. Our mobility, surface potential, and electrode measurements suggest that a negligible fraction of the PIP2 molecules in a cell bind calcium ions, but a significant fraction may bind magnesium and spermine ions.

Adsorption↗
PubMed1988

An in vivo phosphorus nuclear magnetic resonance study of the variations with age in the phosphodiester content of human muscle.

Human gastrocnemius and slow twitch muscles contain phosphodiesters that may be detected in vivo by phosphorus nuclear magnetic resonance (NMR). This work represents a study of 354 spectra obtained from healthy subjects of various ages and from patients with peripheral vascular disease. The analysis of the data indicate a correlation between the concentration of phosphodiesters and age. By comparing the data obtained with healthy subjects and patients it is concluded that the increase in phosphodiesters is not due to disease, but to ageing itself. The significance of this increase is discussed.

Adenosine Triphosphate↗
PubMed1985

Interaction of gentamicin and spermine with bilayer membranes containing negatively charged phospholipids.

We measured the electrophoretic mobility of multilamellar phospholipid vesicles, the 31P NMR spectra of both sonicated and multilamellar vesicles, and the conductance of planar bilayer membranes to study the binding of spermine and gentamicin to membranes. Spermine and gentamicin do not bind significantly to the zwitterionic lipid phosphatidylcholine. We measured the concentrations of gentamicin and spermine that reverse the charge on vesicles formed from a mixture of phosphatidylcholine and either phosphatidylserine or phosphatidylinositol. From these measurements, we determined that the intrinsic association constants of the cations with these negative lipids are all about 10 M-1. This value is orders of magnitude lower than the apparent binding constants reported in the literature by other groups because the negative electrostatic surface potential of the membranes and the resultant accumulation of these cations in the aqueous diffuse double layer adjacent to the membranes have not been explicitly considered in previous studies. Our main conclusion is that the Gouy-Chapman-Stern theory of the aqueous diffuse double layer can describe surprisingly well the interaction of gentamicin and spermine with bilayer membranes formed in a 0.1 M NaCl solution if the negative phospholipids constitute less than 50% of the membrane. Thus, the theory should be useful for describing the interactions of these cations with the bilayer component of biological membranes, which typically contain less than 50% negative lipids. For example, our results support the suggestion of Sastrasinh et al. [Sastrasinh, M., Krauss, T. C., Weinberg, J. M., & Humes, H. D. (1982) J. Pharmacol. Exp. Ther. 222, 350-358] that phosphatidylinositol is the major binding site for gentamicin in renal brush border membranes.

Electric Conductivity↗