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Purpose: 23 Na MRI can be used to quantify in-vivo tissue sodium concentration (TSC), but the inherently low 23 Na signal leads to long scan times and/or noisy or low-resolution images. Reconstruction algorithms such as compressed sensing (CS) have been proposed to mitigate low signal-to-noise ratio (SNR); although, these can result in unnatural images, suboptimal denoising and long processing times. Recently, machine learning has been increasingly used to denoise 1 H MRI acquisitions; however, this approach typically requires large volumes of high-quality training data, which is not readily available for 23 Na MRI. Here, we propose using 1 H data to train a denoising convolutional neural network (CNN), which we subsequently demonstrate on prospective 23 Na images of the calf., Methods: 1893 1 H fat-saturated transverse slices of the knee from the open-source fastMRI dataset were used to train denoising CNNs for different levels of noise. Synthetic low SNR images were generated by adding gaussian noise to the high-quality 1 H k-space data before reconstruction to create paired training data. For prospective testing, 23 Na images of the calf were acquired in 10 healthy volunteers with a total of 150 averages over ten minutes, which were used as a reference throughout the study. From this data, images with fewer averages were retrospectively reconstructed using a non-uniform fast Fourier transform (NUFFT) as well as CS, with the NUFFT images subsequently denoised using the trained CNN., Results: CNNs were successfully applied to 23 Na images reconstructed with 50, 40 and 30 averages. Muscle and skin apparent TSC quantification from CNN-denoised images were equivalent to those from CS images, with <0.9 mM bias compared to reference values. Estimated SNR was significantly higher in CNN-denoised images compared to NUFFT, CS and reference images. Quantitative edge sharpness was equivalent for all images. For subjective image quality ranking, CNN-denoised images ranked equally best with reference images and significantly better than NUFFT and CS images., Conclusion: Denoising CNNs trained on 1 H data can be successfully applied to 23 Na images of the calf; thus, allowing scan time to be reduced from ten minutes to two minutes with little impact on image quality or apparent TSC quantification accuracy., Competing Interests: Declaration of competing interest None., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Purpose: Sodium MRI can be used to quantify tissue sodium concentration (TSC) in vivo; however, UTE sequences are required to capture the rapidly decaying signal. 2D MRI enables high in-plane resolution but typically has long TEs. Half-sinc excitation may enable UTE; however, twice as many readouts are necessary. Scan time can be minimized by reducing the number of signal averages (NSAs), but at a cost to SNR. We propose using compressed sensing (CS) to accelerate 2D half-sinc acquisitions while maintaining SNR and TSC., Methods: Ex vivo and in vivo TSC were compared between 2D spiral sequences with full-sinc (TE = 0.73 ms, scan time ≈ 5 min) and half-sinc excitation (TE = 0.23 ms, scan time ≈ 10 min), with 150 NSAs. Ex vivo, these were compared to a reference 3D sequence (TE = 0.22 ms, scan time ≈ 24 min). To investigate shortening 2D scan times, half-sinc data was retrospectively reconstructed with fewer NSAs, comparing a nonuniform fast Fourier transform to CS. Resultant TSC and image quality were compared to reference 150 NSAs nonuniform fast Fourier transform images., Results: TSC was significantly higher from half-sinc than from full-sinc acquisitions, ex vivo and in vivo. Ex vivo, half-sinc data more closely matched the reference 3D sequence, indicating improved accuracy. In silico modeling confirmed this was due to shorter TEs minimizing bias caused by relaxation differences between phantoms and tissue. CS was successfully applied to in vivo, half-sinc data, maintaining TSC and image quality (estimated SNR, edge sharpness, and qualitative metrics) with ≥50 NSAs., Conclusion: 2D sodium MRI with half-sinc excitation and CS was validated, enabling TSC quantification with 2.25 × 2.25 mm 2 resolution and scan times of ≤5 mins., (© 2023 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals LLC on behalf of International Society for Magnetic Resonance in Medicine.)

Chronic hypertension is a major risk factor for the development of neurodegenerative disease, yet the etiology of hypertension-driven neurodegeneration remains poorly understood. Forming a unique interface between the systemic circulation and the brain, the blood-cerebrospinal fluid barrier (BCSFB) at the choroid plexus (CP) has been proposed as a key site of vulnerability to hypertension that may initiate downstream neurodegenerative processes. However, our ability to understand BCSFB's role in pathological processes has, to date, been restricted by a lack of non-invasive functional measurement techniques. In this work, we apply a novel Blood-Cerebrospinal Fluid Barrier Arterial Spin Labeling (BCSFB-ASL) Magnetic resonance imaging (MRI) approach with the aim of detecting possible derangement of BCSFB function in the Spontaneous Hypertensive Rat (SHR) model using a non-invasive, translational technique. SHRs displayed a 36% reduction in BCSFB-mediated labeled arterial water delivery into ventricular cerebrospinal fluid (CSF), relative to normotensive controls, indicative of down-regulated choroid plexus function. This was concomitant with additional changes in brain fluid biomarkers, namely ventriculomegaly and changes in CSF composition, as measured by T1 lengthening. However, cortical cerebral blood flow (CBF) measurements, an imaging biomarker of cerebrovascular health, revealed no measurable change between the groups. Here, we provide the first demonstration of BCSFB-ASL in the rat brain, enabling non-invasive assessment of BCSFB function in healthy and hypertensive rats. Our data highlights the potential for BCSFB-ASL to serve as a sensitive early biomarker for hypertension-driven neurodegeneration, in addition to investigating the mechanisms relating hypertension to neurodegenerative outcomes., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Perera, Tolomeo, Baker, Ohene, Korsak, Lythgoe, Thomas and Wells.)

Medical therapies achieve their control at expense to the patient in the form of a range of toxicities, which incur costs and diminish quality of life. Magnetic resonance navigation is an emergent technique that enables image-guided remote-control of magnetically labeled therapies and devices in the body, using a magnetic resonance imaging (MRI) system. Minimally INvasive IMage-guided Ablation (MINIMA), a novel, minimally invasive, MRI-guided ablation technique, which has the potential to avoid traditional toxicities, is presented. It comprises a thermoseed navigated to a target site using magnetic propulsion gradients generated by an MRI scanner, before inducing localized cell death using an MR-compatible thermoablative device. The authors demonstrate precise thermoseed imaging and navigation through brain tissue using an MRI system (0.3 mm), and they perform thermoablation in vitro and in vivo within subcutaneous tumors, with the focal ablation volume finely controlled by heating duration. MINIMA is a novel theranostic platform, combining imaging, navigation, and heating to deliver diagnosis and therapy in a single device., (© 2022 The Authors. Advanced Science published by Wiley-VCH GmbH.)

Astrocytes play crucial and diverse roles in brain health and disease. The ability to selectively control astrocytes provides a valuable tool for understanding their function and has the therapeutic potential to correct dysfunction. Existing technologies such as optogenetics and chemogenetics require the introduction of foreign proteins, which adds a layer of complication and hinders their clinical translation. A novel technique, magnetomechanical stimulation (MMS), that enables remote and selective control of astrocytes without genetic modification is described here. MMS exploits the mechanosensitivity of astrocytes and triggers mechanogated Ca 2+ and adenosine triphosphate (ATP) signaling by applying a magnetic field to antibody-functionalized magnetic particles that are targeted to astrocytes. Using purpose-built magnetic devices, the mechanosensory threshold of astrocytes is determined, a sub-micrometer particle for effective MMS is identified, the in vivo fate of the particles is established, and cardiovascular responses are induced in rats after particles are delivered to specific brainstem astrocytes. By eliminating the need for device implantation and genetic modification, MMS is a method for controlling astroglial activity with an improved prospect for clinical application than existing technologies., (© 2021 The Authors. Advanced Science published by Wiley-VCH GmbH.)

Shortages in nursing are the single biggest and most urgent workforce issue that the NHS needs to address. This article sets out the early success of the Nurse Clinical Fellowship Programme established by The Royal Wolverhampton NHS Trust. The unique programme aims to attract and retain nurses by offering a staff nurse post with supported access to academia, fully funded by the NHS Trust. To date, the Trust has attracted 90 nurses (both UK and international registered nurses) to the programme. The programme is also offered internally and the Trust has a cohort of 10 internal nursing staff enrolled onto the programme completing either their BSc (top-up) or Masters, with a second cohort of 60 internal nurses due to start in September 2019. To support international registered nurses with demonstrating their competence to meet Nursing and Midwifery Council requirements the Trust has also established an objective structured clinical examination preparation course designed to embrace and enhance the existing knowledge and skills, while guiding staff in transferring these in line with UK and Trust policies and practices.

Historically, the empirical study of the role of sperm competition in the evolution of sexual traits has been problematic through an enforced reliance on indirect proxy measures. Recently, however, a procedure was developed that uses paternity data to measure sperm competition level directly in terms of males/conception (i.e., the number of males that have sperm present in a female's ampulla at conception). When tested on apes and humans (Hominoidea) this measure proved not only to correlate significantly with the traditionally used measure of relative testes size but also to offer a number of advantages. Here we provide a second test of the procedure, this time using paternity data for the Old World monkeys (Cercopithecoidea). We calculate sperm competition levels (males/conception) for 17 species of wild and free-ranging cercopithecoids and then analyze the data against measures of relative testes size. Calculated sperm competition levels correlate strongly with relative testes size both with and without phylogenetic control at both the species and generic levels. The signal-to-noise ratios inherent in both the past measure of relative testes size and the new measure of sperm competition level from paternity data are discussed. We conclude that although both measures are appropriate for the future study of the role of sperm competition in the evolution of sexual traits, when paternity data are available they provide the more direct and meaningful analytical tool. Not least, they potentially allow a first empirical analysis of the role of sperm competition in the evolution of relative testes size that could then be compared with the wealth of theoretical analyses that already exist., (© 2018 Wiley Periodicals, Inc.)

Objectives: The phrase "level of sperm competition" is used only vaguely in the primate literature. There is also little distinction between the important elements of frequency and intensity of sperm competition, largely because the two current forms of measurement (socio-sexual system and relative testes size) are both proxies which allow neither precision nor fine distinctions. Both measures have critics, socio-sexual system in particular being branded subjective, misleading, and changeable. Testes size is considered the more reliable despite its validation resting on correlations with the other, less reliable, proxy. Recently, genetic paternity studies have been mooted to provide a potentially superior third measure of sperm competition but so far lack a formal interpretive framework. Here we use the published and relatively comprehensive genetic field studies of the Hominoidea to develop such a framework., Materials and Methods: Formulae are derived to convert paternity data into a direct measure of the frequency, intensity, and overall level of sperm competition. We then compare these measures with relative testes size at the study, species, and phylogenetic levels., Results: A significant correlation between level of sperm competition and relative testes size was obtained at each level. These correlations provide independent support for the continuing use of testes size as a proxy measure when such a measure is sufficient. However, they also suggest that paternity data and our formulae yield a viable alternative measure., Discussion: This alternative measure based on paternity data has a number of advantages. Not only is it a potentially direct measure of the level of sperm competition but it also allows the roles of frequency and intensity to be studied separately when of interest., (© 2017 Wiley Periodicals, Inc.)

The time- and space-resolved chemical signatures of gases and vapours formed in solid-state combustion processes are difficult to examine using recent analytical techniques. A machine-smoked cigarette represents a very reproducible model system for dynamic solid-state combustion. By using a special sampling system (microprobe unit) that extracts the formed gases from inside of the burning cigarette, which is coupled to a photoionisation mass spectrometer, it was possible to study the evolution of organic gases during a 2-s cigarette puff. The concentrations of various pyrolysis and combustion products such as 1,3-butadiene, toluene, acetaldehyde and phenol were monitored on-line at different sampling points within cigarettes. A near-microscopic-scale spatial resolution and a 200-ms time resolution were achieved. Finally, the recorded information was combined to generate time-resolved concentration maps, showing the formation and destruction zones of the investigated compounds in the burning cigarette. The combustion zone at the tip of cigarette, where e.g. 1,3-butadiene is predominately formed, was clearly separable from the pyrolysis zones. Depending on the stability of the precursor (e.g. lignin or cellulose), the position of pyrolytic formation varies. In conclusion, it was demonstrated that soft photoionisation mass spectrometry in conjunction with a microprobe sampling device can be used for time- and space-resolved analysis of combustion and pyrolysis reactions. In addition to studies on the model cigarette, further model systems may be studied with this approach. This may include further studies on the combustion of biomass or coal chunks, on heterogeneously catalysed reactions or on spray, dust and gas combustion processes.

Fat mass is linked mechanistically to the cardiovascular system through leptin, a 16 kDa protein produced primarily by adipocytes. In addition to increasing blood pressure via hypothalamic-sympathetic pathways, leptin stimulates monocyte migration, cytokine secretion, and other functions that contribute to atherosclerotic plaque development. These functions are also characteristics of CD16-positive monocytes that have been implicated in the clinical progression of atherosclerosis. This investigation sought to determine if leptin promoted the development of such CD16-positive monocytes. Cells from 45 healthy men and women with age ranging from 20 to 59 years were analyzed. Circulating numbers of CD14(++)16(++) monocytes, which are primary producers of TNFα, were positively related to plasma leptin concentrations (P < 0.0001), with a stronger correlation in men (P < 0.05 for leptin × sex interaction). In vitro, recombinant human leptin induced CD16 expression in a dose-related manner (P = 0.02), with a stronger influence on monocytes from men (P = 0.03 for leptin × sex interaction). There were no sex-related differences in total leptin receptor expression on any monocyte subtypes, relative expression of long versus short isoforms of the receptor, or soluble leptin receptor concentrations in the plasma. The number of circulating CD14(+)16(++) monocytes, which preferentially migrate into nascent plaques, was positively related to systolic blood pressure (R = 0.56, P = 0.0008) and intima-media thickness (R = 0.37, P = 0.03), and negatively related to carotid compliance (R = -0.39, P = 0.02). These observations indicate that leptin promotes the development of CD16-positive monocyte populations in a sex-specific manner and that these subpopulations are associated with diminished vascular function., (© 2014 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society.)

Presents an obituary for Robert Spurlin Waldrop (1912-2012). After receiving a bachelor of arts degree at the University of Oklahoma in 1934 with a major in philosophy and a minor in psychology, Waldrop received a bachelor of divinity degree from the McCormick Theological Seminary in Chicago in 1937. He began graduate work in psychology at the University of Chicago (1937-1940), where he worked with L. L. Thurstone and became interested in the work of William Sheldon. He continued graduate work at the University of Michigan (1940-1943) until he was inducted into the U.S. Navy during World War II. After his discharge from the Navy in 1946, Waldrop returned to Ann Arbor to resume his doctoral studies and was additionally appointed director of the Veterans Service Bureau at the University of Michigan. He completed his doctorate in June 1948 and in the fall accepted a position as dean of students at Vanderbilt University. Waldrop's work with veterans and development of doctoral counseling psychology brought him to the attention of the Department of Veterans Affairs. Waldrop played a pivotal role in the VA's decision to establish doctoral-level counseling psychologists in VA hospitals. He resigned from the VA in 1961 to return to academic life. He accepted a position as professor of psychology in the Department of Psychology at the University of Maryland, College Park, from which he retired in 1979. Throughout his career, Waldrop was involved in both professional and community affairs. Waldrop lived the history of modern psychology and contributed to that history., (© 2013 APA, all rights reserved.)

The 60-year history of the American Psychological Association (APA) Division of Psychologists in Public Service (Division 18) is described. Included are relevant events in the history of the APA that led to the establishment of the division and later events within the APA that influenced the development and activities of the division., (PsycINFO Database Record (c) 2013 APA, all rights reserved.)

In 1946, the Veterans Administration, now the Department of Veterans Affairs (VA), underwent extensive organizational and professional changes to accommodate the health care needs of veterans returning from World War Two. In addition to an introduction and brief history of these changes, three psychologists who began their careers in the VA in the first years after that reorganization discuss their patient care experiences, both as trainees and as staff psychologists.

Soft single photon ionization-time-of-flight mass spectrometry (SPI-TOFMS) and principal component analysis (PCA) were applied for the characterization and discrimination of the chemical patterns of all individual cigarette puffs from the 2R4F University of Kentucky research reference cigarette. The SPI-TOFMS was connected to a smoking machine, and 10 cigarettes were smoked under defined smoking conditions. A total of 41 detected mass signals could be clearly assigned to smoke constituents (e.g., unsaturated hydrocarbons, aromatic species, sulfurous compounds, and nitrogen-containing substances). For further analysis, the on-line recorded mass signals were added up for each cigarette puff resulting in a single summed mass spectrum for each puff. The so-achieved puff-by-puff resolved yields were additionally normalized by the corresponding total ion signal, which eliminated the influences of varying amounts of burnt tobacco. These values were incorporated into a PCA to find differences and similarities in the chemical patterns of the individual cigarette puffs. In addition, absolute (without normalization) and normalized puff resolved yields were used to clarify occurring trends. Thereby, it was shown that the chemical pattern of the first cigarette puff was very unique, whereby extraordinary high yields of unsaturated hydrocarbons are mainly responsible for this. Depending on the smoking procedure, the chemical pattern of the second puff can also be separated from the first and the third puff. In this case, nitrogen-containing substances play an important role. Puffs three to eight show only small but observable differences. These changes are greater influenced by oxygen-containing and sulfurous smoke constituents. The findings reveal that the overall chemical patterns of machine-smoked cigarette puffs vary quite a lot during the smoking process. This lets us assume that the burden of hazardous compounds for the human smoker also differs from puff to puff.

Soft single-photon ionisation (SPI)-time-of-flight mass spectrometry (TOFMS) has been used to investigate the effect of different cigarette-lighting devices on the chemical composition of the mainstream smoke from the first cigarette puff. Lighting devices examined were a Borgwaldt electric lighter, a propane/butane gas lighter, a match, a candle, and the burning zone of another cigarette. To eliminate the effects of the different masses of tobacco burnt by use of the different lighting methods a normalisation procedure was performed which enabled investigation of changes in the chemical patterns of the resulting smoke. When another cigarette was used as the lighting device, elevated levels of ammonia and other nitrogen-containing substances were observed. These are high in the sidestream smoke of the cigarette used for lighting and would be drawn into the mainstream smoke of the cigarette being lit. In contrast, smoke from the cigarette lit by the electric lighter contained slightly higher normalised amounts of isoprene. Lighting the cigarette by use of a candle resulted in larger amounts of substances, e.g. benzene, which most probably originated from thermal decomposition of wax. The composition of the first puff of smoke obtained by use of the three lighting methods with open flames (gas lighter, match, and candle) was usually similar whereas the composition of the smoke produced by use of the electric lighter and the cigarette as the lighter were more unique. The chemical patterns generated by the different lighting devices could, however, be separated by principal-component analyses. Two additional test series were also studied. In the first the cigarette was lit with an electric lighter, then extinguished, the ash was cut off, and the cigarette was re-lit. In the second the cigarette was heated in an oven to 80 degrees C for 5 min before being lit. These treatments did not result in changes in the chemical composition compared with cigarettes lit in the ordinary way.

In recent years much effort has been devoted to assessing the influence of tobacco ingredients on the chemistry and toxicity of cigarette mainstream smoke. All of the studies have indicated that commonly used tobacco ingredients do not change the toxicity of smoke as measured in specified assays. Also, the ingredients have little effect on the levels of most smoke constituents that may be relevant to smoking-related diseases. One exception to this generalisation is formaldehyde, which is generated from saccharides used as tobacco ingredients. However, the past studies have generally used mixtures of ingredients added to the tobacco so that the exact effect of each saccharide in turn could not be precisely determined. This is addressed in the present study. Many diverse studies over the last 30 years have examined particular aspects of formaldehyde in smoke and its generation although no attempt has been made to draw the various aspects together. This has also been addressed in the present paper and an overview is developed on the subject. The experimental results of the present study are rationalised within the framework of this previous knowledge. In the present experimental study, several individual saccharides commonly used as tobacco ingredients have been added to cigarettes, the cigarettes have been machine-smoked and the yields of formaldehyde in the resultant smoke have been compared to those from a control (no ingredient) cigarette. Using four series of cigarettes made on different occasions, the results indicate that all tested sugars added to tobacco increase the yield of formaldehyde in mainstream cigarette smoke under ISO standard smoking machine conditions. Increases up to 60% are observed at maximum sugar levels used on cigarettes. The increases are mostly statistically significant although their magnitudes are variable. These results with formaldehyde are consistent with all previously published studies on the subject. The increases in mainstream formaldehyde are also observed using smoking machine conditions that are more intense than the standard ISO conditions. Different sugars increase mainstream formaldehyde to different extents, which may be due at least partially to the presence of varying amounts of amino compounds in some of the sugars, such as honey and maple syrup. The presence of such compounds has been shown to inhibit the generation of formaldehyde from sugars. In general, the first puff of the cigarette generates abnormally high yields of formaldehyde, and this effect has been shown to persist in the presence of added sugars. In contrast to the situation with mainstream smoke, the levels of formaldehyde in sidestream smoke are not affected by the presence of sugars. The addition of the various saccharides to tobacco also produced some statistically significant effects in the cigarette mainstream yields of six other carbonyl smoke constituents that were analysed at the same time as formaldehyde. These effects were generally small, less than 16%, were not consistent amongst the various cigarette series and lost their significance when the long-term analytical variability was taken into account.

Soft single photon ionisation (SPI)-time-of-flight mass spectrometry (TOFMS) is applied for the characterisation and comparison of puff-by-puff resolved and total yields of cigarette mainstream smoke from single tobacco type cigarettes (Virginia, Oriental, Burley, and Maryland) and the 2R4F University of Kentucky research cigarette. Puff-by-puff characteristics of various smoke components within one cigarette type as well as between different cigarette types can differ tremendously. This is demonstrated by means of a few selected compounds. Puff yields vary between 15 and 106 microm for acetaldehyde, 6 and 57 microm for NO, and between 1 and 8 microm for butadiene. Thereby, cigarettes containing 100% Oriental and Burley tobacco exhibit a very unique behaviour for the first and last puff. Different cultivation and processing methods as well as burning characteristics are most likely responsible for this. Since the 2R4F cigarette contains all four tobacco types it combines features of all of them. However, for some smoke constituents, smoking of the 2R4F reference cigarette results in exceptionally high yields which might not be attributable to the four pure tobacco types, but to other factors. In addition, comparison of the different cigarettes was also carried out by normalising the yields to puff resolved particulate matter. This procedure minimises effects caused by unequal smoke formation and represents another approach in evaluating the data.

Purpose: To examine the effects of a theory-driven tobacco prevention program in sixth-grade children with a family tobacco cessation component implemented by school nurses in conjunction with the initiation of a statewide toll-free Quit Line., Data Sources: Self-report questionnaires completed by the sixth-grade children and their parents/guardians (N= 1024) representing largely rural southern school systems from disparate areas with high prevalence rates of tobacco use and lung cancer diagnoses. Pre- and posttest measures that evaluated the impact of both student and parent/guardian interventions were obtained over a 10-week period. Paired t-tests were used to examine differences between pre- and posttest scores for all student and parent/guardian variables. Repeated-measures analysis of variance was used to examine the effect of parent/guardian smoking on student pre- and posttest scores., Conclusions: The student program resulted in significant improvements in drug knowledge, refusal skills, attitudes, normative expectations, assertiveness, and anxiety reduction techniques. In addition, the effectiveness of several components of the tobacco prevention program for the children was impacted by the smoking status of their parents/guardians. Drug-use intentions and behaviors were lower at posttest for children from homes of nonsmokers versus children from homes of smokers. Parents/guardians consistently reported that smoking was detrimental to themselves, the public, and their children. Of those parents/guardians who identified themselves as smokers (26%) and received cessation materials, 46.4% indicated that the information motivated them to want to quit., Implications for Practice: Tobacco use continues to be the leading cause of preventable death in the United States, with greater than 2000 new youth becoming regular smokers each day. School nurses and nurse practitioners are in various pivotal positions to address tobacco and its related health concerns through delivery of effective family interventions that target children for tobacco prevention and parent/guardian smokers for cessation.

Measurements on the retention of cigarette smoke constituents in the human respiratory tract have been undertake for more than 100 years. The first studies on nicotine retention were begun by Lehmann in Germany in 1903 and published in 1908. The first studies on the retention of smoke particulate matter were published by Baumbereger in the United States in 1923. Since those early publications, many studies have been undertaken, more or less continuously. This article is a review of the work that has been done over the last 100 years, including a large number of unpublished studies undertaken by British American Tobacco in Southampton, UK. The techniques used have evolved over the years and there is a certain amount of variation in the data. However, the general trends in the results are reassuringly consistent. The bulk of the studies indicate that, on average, 60 to 80% of the mainstream smoke particulate matter is retained in the lungs after inhalation. For nicotine, carbon monoxide, nitric oxide, and aldehydes the total retentions are of the order of 90-100, 55-65, 100, and approximately 90%, respectively, during cigarette smoke inhalation. For most smoke constituents the retentions in the mouth only are considerably smaller than in the whole respiratory tract. The lung retention values for smoke particulate matter are dependent on the depth of inhalation, hold time in the lungs, exhalation volume, and other factors. However, the degree of nicotine retention following inhalation is not markedly influenced by changes in respiratory parameters. Furthermore, the percentage retentions for smoke particulate matter and nicotine are smaller for nonsmoking subjects exposed to environmental tobacco smoke than with active smoking. The smoke retentions are related to properties of the smoke aerosol particles and gases and their behavior as they travel through the respiratory tract. This includes particle growth in the respiratory tract and evaporation of gases out of the particles, and relevant aspects of these processes are also reviewed.

Soft single photon ionization (SPI)-time-of-flight mass spectrometry (TOFMS) has been applied for the quantitative puff-by-puff-resolved characterization of selected toxic species in cigarette mainstream smoke, namely, nitric oxide (NO), acetaldehyde, butadiene, acetone, isoprene, benzene, toluene, ethyl benzene, and xylene. The 2R4F research cigarette was investigated for whole smoke (unfiltered) and gas phase (filtered). It has been demonstrated that the existing smoking regime for total smoke analysis (smoke from a complete cigarette) features deficiencies when applied to puff-resolved measurements. This is especially the case for analysis in which a glass fiber filter is used to separate the smoke particulate and gas phases because material is desorbed from the filter and influences succeeding puffs. Regarding whole smoke measurements, succeeding puffs are affected by contamination and memory effects of the smoking machine itself, but to a lower extent. Quantitative puff-resolved smoke profiles show that the puff yields of the various constituents can differ tremendously. Most species' concentrations increase gradually with puff number, which is mainly due to the reduction in length of the cigarette. However, high yields in the first puff are observed for butadiene and isoprene, suggesting different formation mechanisms for these compounds. First results are presented in which these high yields in the first puff are mainly associated with the gaseous fraction of the smoke.

The application of soft photoionization mass spectrometry methods (PIMS) for cigarette mainstream smoke analysis is demonstrated. Resonance-enhanced multiphoton ionization (REMPI) at 260 nm and vacuum ultraviolet light single-photon ionization (SPI) at 118 nm were used in combination with time-of-flight mass spectrometry (TOFMS). An optimized smoking machine with reduced memory effects of smoke components was constructed, which in combination with the REMPI/SPI-TOFMS instrument allows PIMS smoke analysis with a time resolution of up to 10 Hz. The complementary character of both PIMS methods is demonstrated. SPI allows the detection of various aliphatic and aromatic compounds in smoke up to approximately 120 m/z while REMPI is well suited for aromatic compounds. The capability of the instrument coupled to the novel sampling system for puff-by-puff resolved measurements is demonstrated. The feasibility of using the experimental system for intrapuff smoke measurements is also shown. Two main patterns of puff-by-puff behaviors are observed for different smoke constituents. The first group exhibits a constant increase in smoke constituent yield from the first to the last puff. The second group shows a high yield of the constituent in the first puff, with lower and constant or slowly increasing yields in the following puffs. A third group cannot be clearly classified and is a combination of both observed profiles.

Pyrolysis single-photon ionisation (SPI)-time-of-flight mass spectrometry (TOFMS) and statistical analysis techniques have been applied to differentiate three major tobacco types, Burley, Virginia and Oriental, by means of the gas phase. SPI is known as a soft ionisation technique that allows fast and comprehensive on-line monitoring of a large variety of aliphatic and aromatic substances without fragmentation of the molecule ions. The tobacco samples were pyrolysed at 800 degrees C in a nitrogen atmosphere. The resulting pyrolysis gas contained signals from more than 70 masses between m/z 5 and 170. Mass spectra obtained were analysed by principal component analysis (PCA) and linear discriminant analysis (LDA) to distinguish between different tobacco types. Prior variable reduction of the data set was carried out by calculation of the Fisher ratios. Results achieved give information about chemical composition and characteristics of the smoke derived from each tobacco type and enable conclusions on plant cultivation to be drawn. Based on LDA, a model for tobacco type recognition of unknown samples was established, which was cross-checked by additional measurements of each tobacco type. Furthermore, first results on the recognition of tobacco mixtures based on principal component regression (PCR) are presented.

Issues and Purpose: Chronic illnesses, such as asthma experienced by children, are difficult for families and school professionals to manage. This study explored beliefs about asthma and asthma management among schoolchildren, parents, and teachers in an African American school., Design and Methods: Focus groups were conducted with schoolchildren, parents, and teachers. Data were analyzed by content analysis; segments of information were categorized into groups that were later abstracted into themes illustrating beliefs and behaviors about asthma., Results: The children reported fear of not being able to breathe and the limitations of living with asthma. The teachers were concerned that they did not have a sufficient understanding of asthma to manage children's asthma during the school day. Parents described complex lifestyles and the challenges of asthma management.

The effects of 450 tobacco ingredients added to tobacco on the forty-four "Hoffmann analytes" in mainstream cigarette smoke have been determined. These analytes are believed by regulatory authorities in the USA and Canada to be relevant to smoking-related diseases. They are based on lists published by D. Hoffmann and co-workers of the American Health Foundation in New York. The ingredients comprised 431 flavours, 1 flavour/solvent, 1 solvent, 7 preservatives, 5 binders, 2 humectants, 2 process aids and 1 filler. The cigarettes containing mixtures of the ingredients were smoked using the standard ISO smoking machine conditions. The levels of the "Hoffmann analytes" in the smoke from the test cigarettes containing the ingredient mixture were compared to those from control cigarettes without the ingredients. In practice, flavouring ingredients are typically added to tobacco that also contains casing ingredients and reconstituted tobacco materials. In order to keep the tobacco mixtures as authentic as possible, three comparisons have been made in this study. These are: (a) control cigarette containing a typical US blended, cased tobacco incorporating reconstituted tobacco versus test cigarettes that had flavouring ingredients added to this tobacco; (b) control cigarette containing tobacco only versus test cigarettes with the tobacco cased and incorporating flavourings; (c) control cigarette containing tobacco only versus test cigarette incorporating additives made in an experimental sheet material. The significances of differences between the test and control cigarettes were determined using both the variability of the data on the specific occasion of the measurement, and also taking into account the long-term variability of the analytical measurements over the one-year period in which analyses were determined in the present study. This long-term variability was determined by measuring the levels of the 44 "Hoffmann analytes" in a reference cigarette on many occasions over the one-year period of this study. The ingredients were added to the experimental cigarettes at or above the maximum levels used commercially by British American Tobacco. The effect of the ingredient mixtures on total particulate matter and carbon monoxide levels in smoke was not significantly different to the control in most cases, and was never more than 10% with any ingredient mixture. It was found that, in most cases, the mixtures of flavouring ingredients (generally added in parts per million levels) had no statistically significant effect on the analyte smoke yields relative to the control cigarette. Occasionally with some of the mixtures, both increases and decreases were observed for some smoke analyte levels relative to the control cigarette. These differences were generally up to about 15% with the mixtures containing flavouring ingredients. The significance of many of the differences was not present when the long-term variability of the analytical methodology was taken into account. For the test cigarettes with ingredient mixtures containing casing ingredients, there were again no significant changes in smoke analyte levels in most cases. Those changes that were observed are as follows. Decreases in smoke levels were observed with some ingredient mixtures for most of the tobacco specific nitrosamines (up to 24%), NO(x), most of the phenols (up to 34%), benzo[a]pyrene, and some of the aromatic amines and miscellaneous organic compounds on the "Hoffmann list". Increases were observed for some test cigarettes in smoke ammonia, HCN, formaldehyde and lead levels (up to 24%). The significance of the ammonia and lead increases was not present when the long-term variability of the analytical methodology was taken into account. The yields of some carbonyl compounds in smoke were increased in one comparison with an additives mixture containing cellulosic components; in particular, formaldehyde was increased by 68%. This was the largest single change seen in any smoke analyte level in this study. These carbonyls are produced from the pyrolysis of cellulosnyls are produced from the pyrolysis of cellulosic and other polysaccharide materials, present in the additives mixture. With this test cigarette, all tobacco specific nitrosamines, phenols, semi-volatile bases, NO(x) and some aromatic amines and miscellaneous organic compounds on the "Hoffmann list" were decreased, by up to 22%. The significance of many of these differences remained even when the long-term variability of the analytical methodology was taken into account. The levels of all other "Hoffmann analytes" in the smoke were not significantly different to those of the control cigarette. With the exception of the determinations of "tar", nicotine and carbon monoxide, there are currently no internationally recognised standard methods for measurement of the other "Hoffmann analytes". Each laboratory uses its own methods and there are large laboratory-to-laboratory variations, as well as variations over time in a given laboratory. Therefore, it is important that in any comparison of smoke analytes amongst different cigarettes, all the analytes should be measured in the same laboratory and at the same time. This was the case in the present study and all the methods have been validated internally.

This paper presents an overview of a series of studies designed to assess the influence of 482 tobacco ingredients on cigarette smoke chemistry and toxicity. The studies are: pyrolysis of the ingredients; influence of the ingredients on smoke constituents believed by regulatory authorities to be relevant to smoking-related diseases ("Hoffmann analytes"); influence of the ingredients on in vitro genotoxicity and cytotoxicity of smoke partiulate matter; and influence of the ingredients on the inhalation toxicity of smoke. The present paper brings the salient features of these studies together. A pyrolysis technique has been developed which, as far as practicably possible, mimics the combustion conditions inside a burning cigarette. The results from 291 single-substance ingredients indicate that almost a third would transfer out of the cigarette burning zone at least 99% intact (i.e. less than 1% pyrolysis), and almost two thirds would transfer at least 95% intact. Of the ingredients that underwent some degree of pyrolysis, a few "Hoffmann analytes" were detected amongst the pyrolysis products of 19 ingredients. Taking into account maximum use levels, their maximum pyrolysis levels were generally small and often insignificant compared to the levels typically present in smoke. Possible exceptions were acetaldehyde and benzene from the pyrolysis of malic acid. However, subsequent smoke chemistry studies indicated that the maximum levels predicted from pyrolysis of this involatile substance were overestimated, suggesting that malic acid does not undergo complete pyrolysis in the burning cigarette and/or generates acetaldehyde and benzene at similar rates to that of tobacco on a per weight basis. When added to tobacco, many of the ingredient mixtures produced no significant effect on the levels of many of the "Hoffmann analytes" in smoke, while some produced increases or decreases relative to the relevant control cigarettes. The study has concentrated on the increases. Many of the differences were found to be not significant when the long-term variability of the analytical methodology was taken into account. However, even taking this into account, the smoke formaldehyde levels in two of the test cigarettes were significantly increased relative to their controls, by up to 26 microg (73%). These increases are likely to be due to the pyrolysis of sugars, cellulose and other polysaccharide materials. The activity of smoke particulate matter from cigarettes containing tobacco ingredients has been determined with three in vitro bioassays, two for genotoxicity and one for cytotoxicity. These were the Ames test, the mammalian cell micronucleus assay, and the neutral red uptake cytotoxicity assay. Within the sensitivity and specificity of these bioassays, the specific activity of the cigarette smoke particulate matter was not changed by the addition of ingredients to the cigarette. Three 90-day sub-chronic inhalation studies have been undertaken and histopathological and histomorphometric assessments made within the respiratory tracts of animals exposed to smoke from cigarettes containing the various ingredient mixtures and their control cigarettes. The response due to tobacco smoke exposure was not distinguishable between the test and control cigarettes, indicating that the presence of the ingredients had made no discernable differences to the type and severity of the treatment-related changes.

This is the second part of a study in which the effects of adding a range of ingredients to tobacco on the chemistry of cigarette mainstream smoke are assessed. The examination of smoke chemistry has concentrated on those constituents in smoke that regulatory authorities in the USA and Canada believe to be relevant to smoking-related diseases. In this part of the study the effects of 29 casing ingredients and three humectants have been assessed at the maximum levels typically used on cigarettes by British American Tobacco. This brings the total number of ingredients assessed in Parts I and II of this study to 482. The casing ingredients were added at levels of up to 68 mg on the cigarettes. Their effects on smoke constituents were generally larger than the effects of flavouring ingredients, which were added at parts per million levels. Many of the casing ingredient mixtures either had no statistically significant effect on the level of the analytes investigated in smoke relative to a control cigarette, or they produced decreases of up to 44% in some cases. Those analytes that were increased in smoke are highlighted in this paper. The largest increases were for formaldehyde levels, up to 26 microg (73%) in one case, observed from casing mixtures containing sugar. This is most likely due to the generation of formaldehyde by pyrolysis of sugars. Occasional small increases were also observed for other analytes. However, the statistical significance of many of these increases was not present when the long-term variability of the analytical method was taken into account. The significance and possible reasons for the increases are discussed.

Using endogenous lipid substrates, assays of lipid phosphorylation indicated that neuronal nuclei had a considerable superiority in phosphatidic acid (PA) formation when compared with homogenates and other subfractions of cerebral cortex. This predominance of neuronal nuclear PA labelling was linked to a sizable pool of nuclear diacylglycerols that expanded significantly with incubation. PA was also the dominant product of neuronal nuclear lipid phosphorylation reactions. Nuclear envelope preparations and the parent neuronal nuclei showed specific rates of PA formation that were comparable, based upon membrane phospholipid contents. As well, using an exogenous diacylglycerol substrate, the distribution of diacylglycerol kinase activities closely followed phospholipid contents of subfractions derived from the neuronal nucleus during envelope preparation. This evidence suggested an association between diacylglycerol kinase and the neuronal nuclear envelope. Nuclear PA formation increased in the presence of sphingosine, while sphingosine decreased PA formation in other subfractions. Likely sphingosine exerted its effect on nuclear diacylglycerol kinase, as sphingosine did not elevate levels of nuclear diacylglycerols. Phosphoinositidase C was present in the nuclei and inhibitors of this enzyme did decrease PA formation, indicating diacylglycerols from inositides as substrates for nuclear diacylglycerol kinase. The nuclear envelope fraction had a considerably lower specific phosphoinositidase C activity than the parent nuclei, and showed an activation of PA formation by sphingosine, but a less efficient handling of the exogenous diacylglycerol substrate. It is possible that phosphoinositidase C and diacylglycerol kinase are closely situated within the neuronal nuclei, and a loss of the former activity may compromise the latter.

CoA-independent transacylase activities generating alkylacylglycerophosphocholine (AAGPC) from alkylglycerophosphocholine (1-alkyl GPC) were considerably enriched in neuronal nuclei isolated from rabbit cerebral cortex. Specific nuclear transacylation activities were 13 times the corresponding microsomal values. Several lysophospholipids, notably 1-acyl glycerophosphocholine (1-acyl GPC), 1-alkenyl GPC and 1-alkenyl GPE (1-alkenyl glycerophosphoethanolamine) inhibited the transacylation of 1-alkyl GPC. The inhibitory effects of 1-acyl GPC were seen in the presence of MAFP (methyl arachidonoylfluorophosphonate) or free oleate, compounds that inhibit neuronal nuclear lysophospholipase. When neuronal nuclei were preincubated with 1-alkyl GPC, the radioactive AAGPC product served as donor in transacylation reactions, to generate 1-alkyl GPC. In these nuclear reactions, 1-palmitoyl GPE and 1-palmitoyl GPC appeared to be poor acceptor substrates, when compared with corresponding 1-alkyl and 1-alkenyl analogues. The presence of free oleate or MAFP in the reactions containing 1-acyl GPC boosted the release of 1-alkyl GPC from AAGPC. These observations are of particular relevance to brain ischemia in which lysophospholipid, free fatty acid, and platelet-activating factor (PAF) levels rise dramatically. PAF can be made by the nuclear acetylation of 1-alkyl GPC, which is formed by nuclear transacylation mechanisms. Yet transacylase also removes 1-alkyl GPC, and thus this enzyme activity can regulate 1-alkyl GPC availability. Our observations indicate that lysophospholipids promote the formation of 1-alkyl GPC from nuclear AAGPC via transacylation, while free fatty acid likely prolongs the lifetime of 1-acyl lysophospholipids substrates by lysophospholipase inhibition. Similarly, once 1-alkyl GPC is formed, other lysophospholipids effectively compete with this 1-alkyl analogue and reduce its conversion back to AAGPC by transacylation. Free oleate, in this case, sustains 1-acyl lysophospholipid inhibitors of 1-alkyl GPC transacylation. Thus the cycle of transacylation may favour 1-alkyl GPC formation during ischemia, increasing levels of 1-alkyl GPC for nuclear acetylation reactions and PAF formation. The nuclear generation of PAF is of considerable importance as PAF can play regulatory roles in transcription events associated with inflammation.

In this review properties of lipid acetyltransferase enzymes are outlined. The three activities of interest are lyso PAF acetyltransferase (acetyl CoA: 1-alkyl-sn-glycero-3-phosphocholine acetyltransferase), AGP acetyltransferase (acetyl CoA: 1-alkyl sn-glycero-3-phosphate acetyltransferase) and a transacetylase activity that can transfer acetyl groups from PAF to lipid acceptors in the formation of 1-alkenyl-2-acetyl-sn-glycero-3-phosphoethanolamine and N-acetyl sphingosine (C2 ceramide). This review focuses on the role of acetyltransferases and transacetylases within the metabolism of platelet-activating factor and specifically addresses characteristics of the enzymes, including subcellular localization, substrate selectivity, and enzymatic regulation.

Neuronal nuclei isolated from rabbit cerebral cortex were found to be enriched in an NEM-insensitive lysophosphatidic acid (lysoPA) phosphohydrolase activity. LysoPA is an inhibitor of the nuclear lysophosphatidylcholine (lysoPC) lysophospholipase, and by preserving lysoPC levels, lysoPA boosted the nuclear production of the acyl analogue of platelet-activating factor by promoting the acetylation of lysoPC (Baker and Chang, Mol. Cell Biochem., 1999, in press). The nuclear phosphohydrolase converts lysoPA to 1-monoacylglycerol, and thus eliminates this lysoPA inhibition of lysoPC lysophospholipase. The nuclear lysoPA phosphohydrolase specific activity was more than three times that observed for the nuclear lysoPA lysophospholipase (Baker and Chang, Biochim. Biophys. Acta 1438 (1999) 253-263) and represents a more active route for nuclear lysoPA removal. The neuronal nuclear lysoPA phosphohydrolase was inhibited at acidic pH, and also inhibited by calcium ions. The 1-monoacylglycerol product of the phosphohydrolase is rapidly degraded by neuronal monoacylglycerol lipase, an enzyme some sevenfold more active than the phosphohydrolase and sensitive to inhibition by arachidonoyl trifluoromethyl ketone (AACOCF(3)). Both acidic pH and free fatty acid inhibited the lipase. In the absence of AACOCF(3), production of fatty acid from lysoPA substrate could be largely attributed to the sequential actions of the nuclear phosphohydrolase and lipase. This facilitates fatty acid recycling back into phospholipid by lysophospholipid acylation when ATP levels are restored following periods of brain ischemia. At relatively low concentrations, sphingosine-1-phosphate, and alkylglycerophosphate were the most effective phosphohydrolase inhibitors while phosphatidic acid, alkylacetylglycerophosphate and ceramide were without effect. LysoPA is an interesting regulatory molecule that can potentially preserve lysophosphatidylcholine within the nuclear membrane for use in acetylation reactions. Thus conditions relevant to brain ischemia such as falling pH, falling ATP concentrations, rising fatty acid and intracellular calcium levels may, by slowing this metabolic path for lysoPA loss, promote the production of acyl PAF and contribute to the increased levels of the acetylated lipids noted in ischemia.

The aims of this study were to evaluate children's perception of asthma symptoms and to determine a clinically useful method for identifying poor patient perception of airway obstruction. Three methods were used to analyze the relationships among indices of lung function and perception of breathlessness in 35 children. Approximately half the children in our sample did not perceive either airway obstruction or bronchodilation. We propose that <20% improvement in visual analog scale scores post-bronchodilation may provide a simple index for identifying patients with poor perception of airway obstruction, who may be at risk for fatal or near-fatal asthma.

Neuronal nuclei were isolated from rabbit cerebral cortex, and lipid acetylation reactions were studied because of the high nuclear concentration of acetyltransferases that generate platelet activating factor (PAF) and its acyl analogue AcylPAF. The neuronal nuclear acetylation of 1-palmitoyl lysophosphatidylcholine (lyso PC) was found to be increased more than twofold when low concentrations of lyso PC were incubated in acetylation assays in the presence of 1-palmitoyl lysophosphatidic acid (lyso PA) or 1-hexadecyl glycerophosphate (AGP). This effect was not found for a variety of other acidic and neutral 1-acyl lysoglycerophospholipids. At 4 microM concentrations, AGP was the more effective in increasing rates of lyso PC acetylation, while lyso PA was more effective at 25-35 microM. 1-Stearoyl, 1-alkenyl and 1-decanoyl analogues of lyso PA were all less effective than 1-palmitoyl lyso PA. Phosphatidic acid was considerably less effective than lyso PA, while the acetylated analogue of AGP, AAcGP (alkylacetylglycerophosphate), increased rates of lyso PC acetylation to maxima similar to those seen with lyso PA or AGP. In addition, AAcGP promoted these maxima at considerably lower concentrations (2-4 microM). A mechanism for these effects was suggested when nuclear envelopes (NE), isolated in the presence of PMSF, showed these maximal acetylation rates at low lyso PC concentrations, and these rates were not elevated by the presence of lyso PA. PMSF is a protease inhibitor but can also inhibit lysophospholipase activity. We found a nuclear lysophospholipase that degraded lyso PC at rates more than 13 times those of nuclear lyso PC acetylation. PMSF did inhibit this nuclear lysophospholipase, as did lyso PA, AGP and AAcGP. Kinetic analyses of the effects of lyso PA, AGP and AAcGP on lyso PC lysophospholipase indicated that these three lipids acted as competitive inhibitors for the lyso PC substrate. It is possible that low rates of lyso PC acetylation seen in neuronal nuclei at low lyso PC concentrations, are caused by lyso PC loss mediated by a very strong nuclear lysophospholipase. The effects of lyso PA, AGP and AAcGP in boosting rates of lyso PC acetylation likely come from the inhibition of nuclear lysophospholipase and a preservation of lyso PC concentrations. Competing neuronal nuclear reactions for low endogenous levels of lyso PC may regulate the formation of AcylPAF, and rising lyso PA, AGP or AAcGP concentrations can increase rates of nuclear AcylPAF synthesis.

Neuronal nuclei were isolated from immature rabbit cerebral cortex and nuclear lysophospholipase activities studied using two different 1-acyl lysophospholipids: lysophosphatidylcholine (lysoPC) and lysophosphatidic acid (lysoPA). Our interest in these two lysolipids arose from the observation that lysoPA could promote the acetylation of lysoPC by substantially inhibiting a very active nuclear lysoPC lysophospholipase activity, in a competitive manner (R.R. Baker, H. -y. Chang, Mol. Cell. Biochem. (1999) in press). As there was also evidence for nuclear lysoPA deacylation, it was of interest to see whether one activity could possibly utilize both lysolipid substrates. We now have evidence for two separate lysophospholipase activities in neuronal nuclei. The lysoPC lysophospholipase activity was the more active, more highly enriched in the neuronal nuclei, and showed optimal activity at pH 8.4-9, while the lysoPA lysophospholipase activity was maintained over a much broader pH range. The lysoPC activity was substantially inhibited by free fatty acid, and showed considerable stimulation by serum albumin, while the activity utilizing lysoPA was much less affected by these agents. When lysoPC was added to incubations containing radioactive lysoPA, there was no significant inhibition found in rates of release of radioactive fatty acid, indicating that the lysoPA lysophospholipase activity did not utilize the lysoPC substrate. In incubations with lysoPC, MgATP and CoA brought about a sizable formation of phosphatidylcholine whose radioactivity was equally distributed between the sn-1 and sn-2 positions suggesting labelling both directly from the lysoPC substrate and from fatty acid produced by the lysophospholipase activity. By comparison, with the radioactive lysoPA substrate, MgATP and CoA promoted relatively lower levels of phosphatidic acid formation whose principal labelling came directly from the radioactive lysoPA. Largely because of the high activity of the nuclear lysoPC lysophospholipase, there is considerable potential in the neuronal nucleus to limit the use of lysoPC in other reactions, such as the formation of acylPAF (1-acyl analogue of platelet activating factor). It is of interest that conditions associated with brain ischaemia such as increased free fatty acid levels, falling pH and declines in MgATP may allow a preservation of neuronal nuclear lysoPC levels for acetylation. The existence of a separate lysophospholipase activity for lysoPA allows an independent control of lysoPA which can serve as an important regulator of the nuclear lysoPC lysophospholipase.

The inhibitory effects of MgATP on neuronal nuclear acetyltransferase activities were studied using lyso platelet-activating factor (lyso-PAF, 1-alkyl-sn-glycero-3-phosphocholine) and lysophosphatidylcholine (lyso-PC, 1-acyl-sn-glycero-3-phosphocholine). The nuclear (N1) acetylation of lyso-PC was more profoundly inhibited by MgATP. MgATP did not alter the apparent Km for acetyl-CoA in either acetylation reaction. The inhibitory effects of MgATP were not seen for other nucleotides or MgAMP-PCP. Kinase inhibitors such as staurosporine (1 microM), chelerythrine, and R59022 (diglyceride kinase inhibitor I) did not block the MgATP inhibition of either acetylation. However, the addition of phospholipids to the assays indicated a selective inhibitory effect for PIP (25-50 microM) in the nuclear acetylation of lyso-PAF. When N1 was incubated with [gamma-33P]ATP, phosphatidic acid and PIP were the principal radioactive lipid products. While the extent of MgATP inhibition of lyso-PAF acetylation was similar at different concentrations of lyso-PAF, increasing lyso-PC concentrations greatly decreased the MgATP inhibition seen in lyso-PC acetylations. Nuclear envelopes prepared in the presence of PMSF, and fraction N1 exposed to PMSF, did not show the inhibitory effect of MgATP on lyso-PC acetylation. PMSF (an inhibitor of certain phospholipase and lysophospholipase activities) did not reduce the MgATP inhibition of lyso-PAF acetylation. Arachidonoyl trifluoromethylketone, an inhibitor of cytosolic phospholipases A2 and of lysophospholipase activity associated with cPLA2, also blocked the inhibitory effect of MgATP on lyso-PC acetylation. Using radioactive lyso-PC substrate, fraction N1 produced labeled free fatty acid and phosphatidylcholine. In the presence of acetyl-CoA, the production of radioactive phosphatidylcholine increased almost 6-fold when MgATP was also included in these incubations. In the presence of MgATP and acetyl-CoA, PMSF reduced the levels of radioactive free fatty acid and phosphatidylcholine derived from lyso-PC, while Triacsin C, an inhibitor of acyl CoA synthetase, decreased phosphatidylcholine labeling. These findings suggest that MgATP inhibition of lyso-PC acetylation results from a loss of lyso-PC substrate that is largely mediated by nuclear lysophospholipase, acyl-CoA synthetase and lyso-PC acylation. Thus the neuronal nuclear production of Acyl PAF may be regulated by paths that compete for the lyso-PC substrate. In contrast, the acetylation of lyso-PAF is inhibited by PIP, a product of nuclear PI kinase reactions.

The purpose of this study was to develop and evaluate a new instrument, About My Asthma (AMA), to assess stressors affecting quality of life in children with asthma. The AMA is a 55-item, 4-point Likert-type scale. Concurrent validity was established by comparing the AMA with the Pediatric Asthma Quality of Life Questionnaire (PAQLQ). Increased levels of stress measured by the AMA correlated with a decreased quality of life measured by the PAQLQ. We conclude that the AMA is a valid and reliable instrument to measure the quantity and type of stressors experienced by children who have asthma.

Objective: The authors evaluated the response to extended cervicomediastinal thymectomy as a component of the integrated management of patients with myasthenia gravis in a large series of patients from a single institution. The authors evaluated the response to therapy with respect to a graded, multivariate, ordinal scale chosen to reflect the full range of the disease's manifestations., Summary Background Data: A number of series, of varying sizes, describe the response of patients with myasthenia gravis to thymectomy primarily with respect to the bivariate endpoint of the presence or absence of "remission." These studies fail to describe the full spectrum of postoperative disease severity and have been unable to quantify definitively the influence of putative prognostic variables, nor to assess definitively the statistical significance of apparent improvements over time., Methods: The authors evaluated 202 consecutive patients who underwent trans-sternal thymectomy for symptomatic myasthenia gravis from 1969 through 1996 at the Johns Hopkins Hospital. The response to surgery, combined with postoperative medical therapy, was evaluated by a standardized scale reflecting the full spectrum of the disease. These data were analyzed by a novel mean multivariate regression analysis, which allowed the quantification of the statistical significance of apparent responses over time and the evaluation of the independent influence of each of nine putative prognostic indicators., Results: There was no perioperative mortality and a 33% perioperative morbidity. There was a marked clinical response at 6 months to 1 year after surgery that was sustained for at least 10 years thereafter. The median increment of improvement was two (of five) classes. Eighty-six percent and 83% of the patients had improved by at least one class at 5 and 10 years, respectively. These changes were statistically significant (p < 0.001). Whereas the use of extended cervicomediastinal thymectomy was associated with a greater than twofold chance of improvement, compared to conventional trans-sternal thymectomy, neither the pathologic diagnosis (presence of thymoma) nor the age at surgery proved to be negative predictors of postoperative response., Conclusions: Extended cervicomediastinal thymectomy is the procedure of choice as a component of the integrated management of myasthenia gravis, with significant improvement seen in the group as a whole, as well as in subgroups of patients with thymoma and those older than 40 years of age.

Neuronal nuclear fraction N1 was isolated from cerebral cortices of 15-day-old rabbits, and nuclear subfractions prepared, in order to study the location of nuclear lyso platelet-activating factor (lyso-PAF) acetyltransferase and alkylglycerophosphate (AGP) acetyltransferase, and factors that affect the loss of these two nuclear activities. Subfractionation of prelabelled N1 indicated that the nuclear envelope had the highest percentage of the radioactive acetylated products alkylacetylglycerophosphate (AAGP) and PAF, and the distribution of these phospholipids reflected phospholipid distributions in the nuclear subfractions. The majority (95%) of radioactive AAGP and PAF was also recovered in Triton X-100 extracts of prelabelled nuclei, suggesting that these acetylated lipids are located in nuclear membranes rather than in the nuclear matrix/chromatin. Of the nuclear subfractions, the envelope had the highest AGP and lyso-PAF acetyltransferase specific activities which were close to corresponding values seen in the parent N1 fraction. Thus the nuclear AGP and lyso-PAF acetyltransferases were principally localized to the nuclear membranes. Differentials in activity loss were seen for the two acetyltransferase activities. In the nuclear envelope fractions, the lyso-PAF acetyltransferase was the more susceptible to oxidation reactions which could be reversed or blocked by the use of reducing agents. In preincubations, N1 showed greater losses in lyso-PAF acetyltransferase activity than in AGP acetyltransferase activity, losses which were not attributable to oxidation. Addition of cytosolic fraction S3 to preincubations promoted losses for each acetyltransferase in N1, and gave evidence for cytosolic and endogenous nuclear contributions to the activity loss. Addition of okadaic acid to the preincubations did not prevent the decline of either acetyltransferase in intact nuclei, but did diminish the loss of nuclear lyso-PAF acetyltransferase activity promoted by S3 addition, and also blocked the loss of this acetyltransferase seen in preincubations of isolated nuclear envelopes. This suggests that nuclear lyso-PAF acetyltransferase is susceptible to okadaic acid-sensitive nuclear and cytosolic protein phosphatase activities, while AGP acetyltransferase may lose activity by the action of other phosphatases or by other mechanisms within the nucleus.

Neuronal nuclear fractions (N1) isolated from cerebral cortices of 15-day-old rabbits were enriched in two acetyltransferases involved in biosynthetic pathways leading to platelet activating factor (PAF). Alkylglycerophosphate (AGP) acetyltransferase of the de novo biosynthetic path had specific activities in fraction N1 which were 3-times those of the microsomal fraction (P3D) from cerebral cortex. Lyso PAF acetyltransferase of the remodelling path had specific activities in N1 which were 16-times those of P3D and 51-times those of the homogenate. The maximum specific activity observed for the N1 AGP acetyltransferase was 1.4-times the corresponding N1 lyso PAF acetyltransferase value. The pH optimum for the N1 AGP acetyltransferase was within the alkaline range (pH 8-9), while the N1 lyso PAF acetyltransferase showed a much broader pH optimal range which extended over the neutral and physiological pH values. Both acetyltransferases were inhibited by MgATP (0.125-1 mM) or oleoyl CoA (2-10 microM). However, the N1 AGP acetyltransferase could be distinguished from the N1 lyso PAF acetyltransferase by a greater sensitivity to MgATP inhibition. When NaF was not present in the assays, less of the product of N1 AGP acetyltransferase was recovered, likely indicating a hydrolysis of the acetylated AGP. When the AGP and lyso PAF substrates were combined in acetyltransferase assays, the two N1 acetylations appeared to proceed independently. The enrichment of the acetyltransferases, and particularly the lyso PAF acetyltransferase, within the neuronal nuclear fraction is of particular interest with respect to the intracellular effects of PAF which are considered to be involved in nuclear signalling mechanisms.

The activities of enzymes in platelet activating factor (PAF) biosynthetic pathways were analyzed in hippocampal and cerebral cortical regions of normal and ischemic gerbil brain to assess changes in enzyme activities and potential modulators that could explain the accentuated production of PAF seen in ischemia. Global forebrain ischemia was produced by bilateral carotid artery ligation, and the effectiveness of the ligation was shown by free fatty acid release and ATP depletion. Specific activities of 1-alkyl-2-acetyl-sn-glycerol (AAG) choline phosphotransferase, 1-alkyl-sn-glycero-3-phosphate (AGP) acetyl transferase, and 1-alkyl-sn-glycero-3-phosphocholine (lyso PAF) acetyl transferase in tissue homogenates were in the ratio 4:1:0.1, respectively. Sham-operated and ischemic or ischemic-reperfused tissues showed similar activities for individual enzymes, indicating that enzyme levels or activation states did not change in ischemic or reperfused tissues. However, small metabolites (relevant to ischemia) added to the in vitro assays did modify enzyme activities. Physiological concentrations of MgATP severely inhibited AGP acetyl transferase activity, and this resulted in the ratio of AGP acyl transferase to AGP acetyl transferase activities changing from 48:1 in the presence of 2.5 mM MgATP to 6:1 in the absence of MgATP. This suggests that falling ATP levels in cerebral ischemia may promote the de novo pathway of PAF biosynthesis by releasing inhibition of AGP acetyl transferase. Lyso PAF acetyl transferase was much less active than AGP acetyl transferase and was also inhibited by MgATP. AAG choline phosphotransferase was not inhibited by MgATP but was inhibited by calcium. However the superior specific activity of the choline phosphotransferase in comparison with the AGP acetyl transferase suggested that the lowered choline phosphotransferase activity in the presence of rising intracellular calcium would not seriously compromise the synthesis of PAF by the de novo route. Both acetyl transferase enzymes were also inhibited by oleoyl CoA.

In this review, evidence is summarized for the production of PAF in brain, in response to stimulation associated with pathology. As well, there is a growing literature on the duality of actions of this lipid autocoid upon nervous tissue, indicated by extracellular and intracellular actions and binding sites for PAF in brain. The metabolic routes to PAF can be divided into the de novo and remodelling pathways of synthesis. The de novo route consists of 1-alkyl glycerophosphate acetyltransferase, and the subsequent actions of distinct phosphohydrolase and cholinephosphotransferase activities. This acetyltransferase can be activated by phosphorylation, and inhibited by MgATP and fatty acyl CoA thioesters, inhibitions which have particular relevance to brain ischemia. There is also evidence that the cholinephosphotransferase is controlled by phosphorylation, and regulated by levels of CDP-choline. The remodelling pathway to PAF relies upon the actions of phospholipase A2 or CoA-independent transacylases to generate the 1-alkyl glycerophosphorylcholine, as substrate for a distinct acetyltransferase. Following stimulation, rising intracellular calcium may trigger arachidonate selective cytosolic phospholipase activity which leads to increased PAF synthesis. The 1-alkyl glycerophosphocholine acetyltransferase activity is quite small in brain in comparison with the de novo acetyltransferase activity, and is also controlled by phosphorylation. Evidence has been presented for the actions of both pathways in brain, in response to biologically relevant stimulation pertinent to the disease state.