Outcomes of Patients with a pH<7.0 Presenting to the Emergency Department (OPpHED Study)

Objectives The aim of this study was to assess the mortality and predictive factors in patients presenting with a pH<7.0 to the emergency department (ED). Methods A retrospective study of patients presenting to the ED of University Hospital Galway with a pH<7.0 from January 2014 to December 2017 was performed. A pH<7.0 on arrival to the ED from either an arterial or venous sample as measured by the blood gas analyser machine were assessed for inclusion. Results A total of 130 patients presented to ED over a 4-year period, with a mean age of 58 ±20 years. Eighty-one (63%) patients of the total cohort were male. In terms of aetiology of presentation, 66 (51%) cases were from cardiac arrest (CA), while the remaining 64 (49%) cases were non-cardiac arrest (NCA) related. Twenty-eight-day mortality was 69.5% overall, with significant mortality in the CA group (89%) compared to the NCA group (48%) (p<0.00). A modified early warning score (MEWS) (odds ratio [OR] 1.37, 95% CI: 1.18-1.59) and PCO2 ([OR] 1.35, 95% CI: 1.08-1.68.) were predictive of mortality. Conclusion In patients presenting to the ED with a pH of <7.0 the overall mortality was 69.5%, with survival more likely in NCA aetiologies. Mortality was associated with higher pCO2 and MEWS.

Vitamin D Deficiency and Insufficiency Prevalence in the West of Ireland - A Retrospective Study

OBJECTIVES

Vitamin D plays an important role in calcium homeostasis and is essential for normal bone growth and remodeling. Previous studies of acutely ill and institutionalized older women in Galway revealed that vitamin D insufficiency is extremely common. We aimed to evaluate age and gender-related rates of vitamin D insufficiency and deficiency in adult patients attending their General Practitioners in the same region.

DESIGN

A retrospective cohort study.

SETTING

General practices in Galway, a city located on the west coast of Ireland, latitude 53.17 North.

PARTICIPANTS

A total of 15,708 consecutive blood samples from adults attending their General Practitioners between January 2013 and December 2014 were sent to the Clinical Biochemistry Laboratory in the University Hospital Galway for vitamin D level testing. 73% were from women.

INTERVENTION

Data were collected and grouped according to age, sex and season. Vitamin D levels (25OHD) were categorised into deficiency (<25nmol/L), insufficiency (25-50nmol/L) and sufficiency ( >50nmol/L).

MEASUREMENTS

Median and interquartile range were reported as vitamin D levels were not normally distributed. Descriptive statistics were performed using STATA/MP 13.1 for Mac.

RESULTS

While vitamin D levels were sufficient in 56.4% (n=8,496), they were insufficient in 32.4% (n=4,891) and deficient in 11.2% (n=1,691). Of the deficient group, 19%( 325) had levels <15nmol/L consistent with profound deficiency. Men were more likely than women to be deficient (12% (n=489) vs. 10.9% (n=1,202)) and insufficient (38.0% (n=1,550) vs. 30.4% (n=3,341)) (p<0.01). Highest rates of deficiency were seen in those 81-97 years (19.4% (n=136)) and 18-40 years (13.8% (n=543)), the former group showing less seasonal variation.

CONCLUSION

Overall prevalence of insufficiency is similar to those in national and European studies published recently. However, there is a high possibility that those most vulnerable to vitamin D deficiency were underrepresented in this cohort, when results from previous studies in the same region are considered. Further prospective studies are needed to guide treatment with supplementation of vitamin D for appropriate subgroups.

Surface-enhanced Raman scattering measurement from a lipid bilayer encapsulating a single decahedral nanoparticle mediated by an optical trap

We present a new technique for the study of model membranes on the length-scale of a single nano-sized liposome. Silver decahedral nanoparticles have been encapsulated by a model unilamellar lipid bilayer creating nano-sized lipid vesicles. The metal core has two roles (i) increasing the polarizability of vesicles, enabling a single vesicle to be isolated and confined in an optical trap, and (ii) enhancing Raman scattering from the bilayer, via the high surface-plasmon field at the sharp vertices of the decahedral particles. Combined this has allowed us to measure a Raman fingerprint from a single vesicle of 50 nm-diameter, containing just ∼10⁴ lipid molecules in a bilayer membrane over a surface area of <0.01 μm², equivalent to a volume of approximately 1 zepto-litre. Raman scattering is a weak and inefficient process and previous studies have required either a substantially larger bilayer area in order to obtain a detectable signal, or the tagging of lipid molecules with a chromophore to provide an indirect probe of the bilayer. Our approach is fully label-free and bio-compatible and, in the future, it will enable much more localized studies of the heterogeneous structure of lipid bilayers and of membrane-bound components than is currently possible.

B-type natriuretic peptide in the cardiology department

Heart Failure is one of the fastest growing cardiovascular diseases of the 21st century. Echocardiogram is considered the gold standard for diagnosis, but is costly, time consuming and not readily accessible to all patients. Our aim was to assess the diagnostic utility of BNP to risk stratify patients for ECHO. Seventy-four GP referred, non-pregnant patients of > or = 18 years with a working diagnosis of HF were recruited. Patients were given two appointments to attend the Cardiology Department and at each, were examined by the same cardiologist, had their medications recorded and blood drawn for BNP analysis. ECHO was performed at the second visit. The diagnosis of HF was confirmed in 49 of 74 patients (66%). The clinical utility of BNP to rule-in HF was evaluated using ROC curve analysis. The AUC was satisfactory at 0.691 (C.I. 0.573-0.793). The positive likelihood ratio (+LR) was 5.87, negative likelihood ratio (-LR) was 0.58, the positive predictive value was 92% and a negative predictive value was 47%. One-third of patients (n = 25) had a BNP >178 pg/mL, 23 of whom had HF confirmed. At this decision threshold BNP correctly classified 23 of 25 patients who were confirmed not to have HF (Specificity for HF of 92%). A BNP of > or = 178 pg/mL can be used to prioritise GP patients for ECHO.

Trimester-specific reference intervals for IFCC standardised haemoglobin A(1c): new criterion to diagnose gestational diabetes mellitus (GDM)?

We established trimester-specific reference intervals for IFCC standardised HbA(1c) in 311 non-diabetic Caucasian pregnant women (n = 246) and non-pregnant women (n = 65). A selective screening strategy based on risk factors for gestational diabetes was employed. Pregnancy trimester was defined as trimester 1 (T1, n = 40) up to 12 weeks + 6 days, trimester 2 (T2, n = 106) 13 to 27 weeks + 6 days, trimester 3 (T3, n = 100) > 28 weeks to delivery. The normal HbA(1c) reference interval for Caucasian non-pregnant women was 29-37 mmol/mol (DCCT: 4.8-5.5%), T1: 24-36 mmol/mol (DCCT: 4.3-5.4%), T2: 25-35 mmol/mol (DCCT: 4.4-5.4%), and T3: 28-39 mmol/mol (DCCT: 4.7-5.7%). HbA(1c) was significantly decreased in trimesters 1 (P < 0.01) and 2 (P < 0.001) compared to non-pregnant women. Retrospective application of selective screening to Caucasian women of the Atlantic DIP cohort determined that 5,208 met the criteria. 945 of those women (18.1%) were diagnosed with Gestational Diabetes Mellitus (GDM) using the International Association of Diabetes and Pregnancy Study Groups (IADPSG) glucose concentration thresholds. HbA(1c) measurement within 2 weeks of the diagnostic Oral Glucose Tolerance Test (OGTT) was available in 622 of 945 (66%). Applying the decision threshold for T2: HbA(1c) > 35 mmol/mol (DCCT > 5.4%) identified 287 of 622 (46%) of those with GDM. HbA(1c) measurement in T2 (13 to 27 weeks) should be included in the diagnostic armamentarium for GDM. This would reduce the need for diagnostic OGTT in a significant number of women.

Label-free critical micelle concentration determination of bacterial quorum sensing molecules

A practical label-free method for the rapid determination of small-molecule critical micelle concentration (CMC) using a fixed-angle light-scattering technique is described. Change in 90° light scattering at a fixed wavelength of incident radiation with increasing bacterial quorum molecule concentration and the observation of a break point is used to determine CMC. In our study, this technique is utilized to investigate the aqueous CMC of previously uncharacterized Pseudomonas aeruginosa quorum sensing signaling molecules (QSSM) belonging to the n-acylhomoserine lactone and 2-alkyl-4-quinolone classes. Several were found to form micelles within a physiologically relevant concentration range and potential roles of these micelles as QSSM transporters are discussed. The influence of temperature and the presence of biological membranes or serum proteins on QSSM CMC are also investigated and evidence is obtained to suggest the QSSMs studied are capable of both membrane and serum protein interaction. This demonstrates that the fixed-angle light-scattering technique outlined can be used simply and rapidly to determine small-molecule CMC under a variety of conditions.

Studying protein binding to conjugated gold nanospheres; application of Mie light scattering to reaction kinetics

The study of protein interactions is an area of much interest, particularly towards obtaining more detailed information about biological processes. Current methods involve the use of complicated, specialised techniques which are beyond the scope of most laboratories. Here, we show how information about the binding of proteins to conjugated gold nanospheres can be obtained using straightforward experimental techniques. A Perkin Elmer LS 55 luminescence spectrometer was used to observe the changes in light scattering caused by the binding of complementary proteins to conjugated nanoparticles, measured by the intensity change over time. Mie theory simulations have been used to predict the expected observations and to quantify the changes in intensity as a function of surface coverage. Further kinetic studies have been carried out at 530 nm to obtain more detailed information about the processes involved in the binding reaction. Thus, we have demonstrated that the interaction of proteins can be studied using a straightforward method which provides information about surface coverage and reaction kinetics.

Toward a mathematical model of the assembly and disassembly of membrane microdomains: comparison with experimental models

We study a model system in which lipid bilayers are created using variable (precisely known) proportions of phosphatidylcholine and cholesterol. The model membranes exhibit cholesterol-enriched microdomains that are analogous to the so-called "lipid rafts" that form in living cells. After briefly presenting some experimental results, we formulate and solve a novel mathematical model based on the Smoluchowski equations for coagulation and fragmentation. We present a comparison between the distribution of lipid-raft areas observed in experimental lipid bilayers, and that distribution predicted by the theoretical model. Excellent agreement between the experiments and theory is obtained, with minimal parameter fitting.

Two-photon fluorescence surface wave microscopy

This paper demonstrates the principle of two-photon surface wave microscopy with a view to applications on biological samples. We describe a modified scanning optical microscope, which uses specially prepared coverslips. These coverslips are designed to support the propagation of surface waves capable of large field enhancements. We also discuss the beam conditioning necessary to ensure efficient use of the available illumination. Two-photon surface wave fluorescent excitation is demonstrated on fluorescent nanospheres, demonstrating a point spread function width of approximately 220 nm at an illumination wavelength of 925 nm. The potential of non-linear surface wave excitation for both fluorescence and harmonic imaging microscopy is discussed.

The effects of anabolic-androgenic steroids upon resting and peak exercise left ventricular heart wall motion kinetics in male strength and power athletes

Previous investigations reported alterations in myocardial fibres and systolic function associated with anabolic-androgenic steroid consumption by athletes. Advances in bio-medical technology have allowed further investigation in assessing the possible effects of anabolic-androgenic steroids on gross left ventricular kinetics. Twenty-three male strength and power athletes with a past and current history of anabolic-androgenic steroid consumption (x 46 days, range 28 days to 70 days), were compared to 23 controls. Testing consisted of resting and immediate post-exercise transthoracic left ventricular wall cardiokymograms. Statistical results identified no difference over time between groups or condition. Cardiokymographic waveform analysis found 32.61% of all (n =184) waveforms to be abnormal (Type II, n = 56 or Type III, n = 4). There were 14 treatment subjects (60.87%) who demonstrated an abnormal waveform as compared to 9 controls (39.13%). A significant difference (p < or = 0.01) in the overall proportions of waveform types was identified where the treatment group exhibited 41.30% abnormal waveforms, compared to 23.91% by controls. Additionally, two athletes (1 treatment, 1 control) demonstrated abnormal left ventricular wall motions (Type III) analogous to impaired left ventricular performance. The results indicated: (a) highly strength trained athletes with no history of anabolic-androgenic steroid usage exhibited an unexpected high incidence of Type II waveforms (28.26% pre/23.91% post); (b) a comparable group of strength trained athletes using anabolic-androgenic steroids exhibited a significantly higher percentage of abnormal waveforms as compared to controls (34.78% pre/37.21% post). Based on these results, high intensity strength training with and without anabolic-androgenic steroid supplementation induced alterations in the left ventricular wall motion.

Analysis of thyroid hormone responsive gene expression in osteoblastic cells

Thyroid hormones regulate gene expression to influence the development and metabolism of many tissues including bone. The identification of genes that are regulated by thyroid hormones during skeletal development requires sensitive and quantitative techniques that are not limited by small amounts of available tissue and RNA. We have compared the efficiencies of differential display and poly A PCR subtraction hybridisation methods for the detection of thyroid hormone responsive genes expressed in osteoblastic cells. The utility of each technique was evaluated with respect to its sensitivity, specificity, cost and ability to identify novel genes. Subtraction hybridisation was rapid and more efficient in all categories. Poly A PCR facilitates quantitative and representative global amplification of cDNAs from low concentrations of RNA extracted from small tissue samples. The method, in combination with microarray analyses, may prove useful as an additional, complementary strategy to subtraction hybridisation for the analysis of differential gene expression in tissues where sample size is limiting.

Measuring and visualizing single molecular interactions in biology

In recent years, considerable attention has focused upon the biological applications of the atomic force microscope (AFM), and in particular in its ability to explore biomolecular interaction events at the single molecule level. Such measurements can provide considerable advantages, as they remove the data averaging inherent in other biophysical/biochemical approaches that record measurements over large ensembles of molecules. To this end AFM has been used for both the high-resolution imaging of a range of individual biological molecules and their complexes, and to record interaction forces between single interacting molecules. In a recently initiated project we have begun to utilize these approaches to explore the interactions of a range of biologically important peptides with model and cell membrane surfaces. In this review, the potential value of AFM for the investigation of a range of biomolecular interaction events will be discussed, but highlighting in particular its potential for the study of interactions of peptides/proteins with biological membranes.

Intermolecular interactions with/within cell membranes and the trinity of membrane potentials: kinetics and imaging

The interactions of (macro-)molecules with biological membranes underlies much of cell biology. This paper outlines many of the factors that must be taken into account in order to understand fully the nature of these interactions. These include some roles of the membrane potentials including features of the surface and dipole potentials. Several fluorescence detection technologies directed towards these are outlined that offer high-resolution experimental determination of the intermolecular interactions by measuring small changes of these potentials resulting from specific interactions of many kinds of molecular species. The possibilities for making single-cell spatial imaging measurements of such interactions is also described. Examples are used to indicate the feasibility of identifying and tracking localized interactions on the membrane surface in real-time. Some of this work points to the possibility that the membrane dipole potential spatially varies about the cell surface, particularly within membrane microdomains such as ‘rafts’. Such variation is suggested to underlie the altered behaviour of signalling systems within rafts and offer the means of an additional level of biological control.

Effects of the membrane dipole potential on the interaction of saquinavir with phospholipid membranes and plasma membrane receptors of Caco-2 cells

The combined use of the membrane surface potential fluorescent sensor fluorescein phosphatidylethanolamine (FPE) and the membrane dipole potential fluorescent sensor di-8-ANEPPS to characterize the interaction of molecules with model and cellular membranes and to asses the influence of the dipole potential on the interaction is reported. The study of the human immunodeficiency virus protease inhibitor saquinavir with Caco-2 cells and phospholipid membranes reveals that the compound interacts with the lipidic bilayer of model membranes with a simple hyperbolic binding profile but with Caco-2 cells in a cooperative way involving membrane receptors. Additional studies indicated that colchicine acts as a competitor ligand to saquinavir and suggests, in agreement with other reports, that the identity of the saquinavir "receptor" could be P-glycoprotein or the multiple drug resistance-associated protein. The modification of the magnitude of the membrane dipole potential using compounds such as cholesterol, phloretin, and 6-ketocholestanol influences the binding capacity of saquinavir. Furthermore, removal of cholesterol from the cell membrane using methyl-beta-cyclodextrin significantly decreases the binding capacity of saquinavir. Because removal of cholesterol from the cell membrane has been reported to disrupt membrane domains known as "rafts," our observations imply that the membrane dipole potential plays an important role as a modulator of molecule-membrane interactions in these membrane structures. Such a role is suggested to contribute to the altered behavior of receptor-mediated signaling systems in membrane rafts.

Ultrashort-laser-pulse measurement using swept beams

We demonstrate a frequency-resolved optical gating (FROG) device that uses a sweepshot geometry that combines the advantages of multishot and single-shot pulse-measurement devices, has only one moving part, a galvanometer, and requires no computer control. Like a multishot device, it focuses the beam to a small spot (rather than a line focus) and has a high intensity in the nonlinear medium. Like single-shot devices, it makes measurements quickly, generating an entire FROG trace on a single camera screen (rather than requiring many camera downloads).

Highly simplified device for ultrashort-pulse measurement

We show that a frequency-resolved optical gating device using (1) a thick nonlinear crystal to replace the usual thin crystal and spectrometer and (2) a Fresnel biprism to replace the beam splitter and delay line yields a remarkably simple single-shot ultrashort-pulse intensity-and-phase measurement device with no sensitive alignment parameters and significantly greater sensitivity.

Effect of phloretin on the percutaneous absorption of lignocaine across human skin

The potential use of phloretin, a polyphenolic compound, as a penetration enhancer in the transdermal delivery of lignocaine hydrochloride (L-HCl) has been investigated. Standard in vitro skin permeation methods, using excised human skin, were used to characterize the percutaneous absorption of L-HCl. Initially, phloretin was applied to the skin surface as a methanolic solution. The skin samples were treated 12 h prior to application of the lignocaine donor solution, which was buffered at pH 4.0 and 7.0. The data obtained from the methanolic solutions at pH 4.0 show a 3.2-fold increase of the cumulative amount permeated after 24 h compared with the control. A second series of experiments were conducted using unilamellar phosphatidylcholine liposomes instead of methanol as a vehicle for the phloretin. The L-HCl amount permeated from liposomal-pretreated skin was 5.4-fold (p < 0.05) higher than the control within 24 h. In addition to the diffusion experiments, pressure area isotherms were recorded on a Langmuir-Blodgett trough using the model skin lipid ceramide-2. They showed a slight increase in the area occupied per lipid molecule of 1.04 nm(2) at constant surface pressure. This result indicates an interaction between the model lipid and phloretin. The results suggest the potential use of phloretin as penetration enhancer in the delivery of L-HCl through skin.

Increased-bandwidth in ultrashort-pulse measurement using an angle-dithered nonlinear-optical crystal

We show that the usual phase-matching-bandwidth constraint in ultrashort-laser-pulse measurement techniques is overly restrictive. Specifically, the phase-matching bandwidth need not exceed the pulse bandwidth on every pulse. Instead, only the phase-matching bandwidth integrated over the measurement period need exceed the pulse bandwidth. We show that angle-dithering a second-harmonic-generation crystal that is otherwise too narrowband (that is, too thick) can yield sufficient phase-matching bandwidth and an accurate pulse measurement. We apply this technique to frequency-resolved optical gating (FROG) and show that accurate pulse measurements can be made using a comparatively very thick and hence narrowband crystal. An additional advantage of using a thick crystal is increased signal strength.

Effect of sequential transdermal progesterone cream on endometrium, bleeding pattern, and plasma progesterone and salivary progesterone levels in postmenopausal women

BACKGROUND

Transdermal progesterone is being used in some countries as a purported treatment for menopausal symptoms, either alone or prescribed in conjunction with estrogen, but little information exists regarding the biological activity and effectiveness of this method of delivery of progesterone in protecting the endometrium from excess proliferation. This study was designed to evaluate the use of sequential transdermal progesterone. End-points evaluated included endometrial cellular response and bleeding pattern as well as plasma hormone levels and salivary progesterone estimations.

METHOD

Twenty-seven postmenopausal women were treated with continuous transdermal estrogen (28-day cycle) and a cream containing 16, 32 or 64 mg of progesterone in each 4-cm extrusion from a tube of Pro-Feme administered daily in a sequential (days 15-28 of cycle) regimen. Blood and endometrial samples were analyzed for progesterone response prior to therapy, after the first 14 days of unopposed transdermal estrogen and following 14 days of transdermal progesterone. Saliva samples were taken during the last 14 days of the 84-day study, when the final progesterone cream therapy was being applied.

RESULTS

Hormone assay indicated that physiological levels of estradiol were achieved, but progesterone levels were insufficient to induce any detectable change in the endometrium. Only one patient experienced bleeding during the study period. Levels of salivary progesterone were so variable as to be considered completely unreliable in determining the potential influence on biological activity.

INTERPRETATION

Pro-Feme transdermal progesterone administered in a 16-, 32- or 64-mg daily dose for 14 days in a sequential regimen does not appear to be effective in inducing a secretory change in a proliferative endometrium. Salivary progesterone levels were not of value in managing the therapy of postmenopausal women.

Characterization of the sequence of interactions of the fusion domain of the simian immunodeficiency virus with membranes. Role of the membrane dipole potential

The simian immunodeficiency virus fusion peptide constitutes a 12-residue N-terminal segment of the gp32 protein that is involved in the fusion between the viral and cellular membranes, facilitating the penetration of the virus in the host cell. Simian immunodeficiency virus fusion peptide is a hydrophobic peptide that in Me(2)SO forms aggregates that contain beta-sheet pleated structures. When added to aqueous media the peptide forms large colloidal aggregates. In the presence of lipidic membranes, however, the peptide interacts with the membranes and causes small changes of the membrane electrostatic potential as shown by fluorescein phosphatidylethanolamine fluorescence. Thioflavin T fluorescence and Fourier transformed infrared spectroscopy measurements reveal that the interaction of the peptide with the membrane bilayer results in complete disassembly of the aggregates originating from an Me(2)SO stock solution. Above a lipid/peptide ratio of about 5, the membrane disaggregation and water precipitation processes become dependent on the absolute peptide concentration rather than on the lipid/peptide ratio. A schematic mechanism is proposed, which sheds light on how peptide-peptide interactions can be favored with respect to peptide-lipid interactions at various lipid/peptide ratios. These studies are augmented by the use of the fluorescent dye 1-(3-sulfonatopropyl)-4-[beta[2-(di-n-octylamino)-6-naphthyl]vinyl ] pyridinium betaine that shows the interaction of the peptide with the membranes has a clear effect on the magnitude of the so-called dipole potential that arises from dipolar groups located on the lipid molecules and oriented water molecules at the membrane-water interface. It is shown that the variation of the membrane dipole potential affects the extent of the membrane fusion caused by the peptide and implicates the dipolar properties of membranes in their fusion.

Membrane interactions of the putative fusion peptide (MF alpha P) from fertilin-alpha, the mouse sperm protein complex involved in fertilization

Mammalian fertilization depends upon successful binding and fusion between the membranes of the spermatozoon and the oocyte. These processes are thought to be mediated by a series of protein-protein interactions in which sperm antigens known as fertilins are thought to play a key role. Using a recently developed fluorescence technique, the interactions of the oligopeptide sequence corresponding to the fusogenic domain of mouse fertilin-alpha (MF alpha P) and phospholipid vesicles have been investigated. Following stopped-flow mixing, MF alpha P bound rapidly to phospholipid membranes in a co-operative manner with a Hill coefficient of 2.4 and binding rate constants in excess of 1000 s-1. The co-operative nature of the binding process is suggested to represent evidence of a structural mechanism to prevent egg fertilization by immature spermatozoa. The subsequent membrane insertion was found to take place over a longer time period (with rate constants of up to 6.3 s-1), and was linear with respect to peptide concentration. Comparison of these processes with similar time-resolved circular dichroism measurements revealed that changes in peptide secondary structure were very rapid. Fourier transform infrared spectroscopy measurements confirmed changes in the secondary structure of MF alpha P during interaction with PC phospholipid membranes, indicating that the peptide is mainly present in a beta-structure with a small proportion of alpha-helix. These results are consistent with the hypothesis that fertilin-alpha is the fusogenic species with an important role in fertilization.

Ligand-dependent conformational equilibria of serum albumin revealed by tryptophan fluorescence quenching

Ligand-dependent structural changes in serum albumin are suggested to underlie its role in physiological solute transport and receptor-mediated cellular selection. Evidence of ligand-induced (oleic acid) structural changes in serum albumin are shown in both time-resolved and steady-state fluorescence quenching and anisotropy measurements of tryptophan 214 (Trp214). These studies were augmented with column chromatography separations. It was found that both the steady-state and time-resolved Stern-Volmer collisional quenching studies of Trp214 with acrylamide pointed to the existence of an oleate-dependent structural transformation. The bimolecular quenching rate constant of defatted human serum albumin, 1.96 x 10(9) M-1 s-1, decreased to 0.94 x 10(9) M-1 s-1 after incubation with oleic acid (9:1). Furthermore, Stern-Volmer quenching studies following fractionation of the structural forms by hydrophobic interaction chromatography were in accordance with this interpretation. Time-resolved fluorescence anisotropy measurements of the Trp214 residue yielded information of motion within the protein together with the whole protein molecule. Characteristic changes in these motions were observed after the binding of oleate to albumin. The addition of oleate was accompanied by an increase in the rotational diffusion time of the albumin molecule from approximately 22 to 33.6 ns. Within the body of the protein, however, the rotational diffusion time for Trp214 exhibited a slight decrease from 191 to 182 ps and was accompanied by a decrease in the extent of the angular motion of Trp214, indicating a transition after oleate binding to a more spatially restricted but less viscous environment.

Amino acid sequences which promote and prevent the binding and membrane insertion of surface-active peptides: comparison of melittin and promelittin

The temporal sequence of molecular events involved in the interactions of a number of related peptides with membranes are revealed using two complementary fluorescence techniques. Comparative studies are reported of the interactions of melittin, promelittin and a melittin analogue with trp-19 replaced with Ile and the n-terminal gly replaced with a trp residue, with phosphatidylcholine membranes. It is shown that the interaction of the n-terminal region of melittin rapidly binds and inserts into the body of the membrane with a rate constant of around 367 s-1. This is followed by a slightly slower membrane insertion of the trp-19 region with a rate constant of around 112 s-1. The positive charges of the melittin molecule then come into close proximity with the membrane with rate constants around 27 s-1. Finally, these charged regions insert into the hydrophobic core of the membrane with rate constants of about 0.3 s-1. The effect of incorporating net negative charge onto the membrane surface in the form of 15 mole % phosphatidylserine, augments by about threefold, the binding of the charged domains of the melittin molecule. The observations of the melittin interactions are compared with the melittin-precursor protein, promelittin. Sections of the promelittin molecule are also found to bind and insert into the body of the phospholipid membrane, although nearly 30 times less rapidly than melittin. No charged sections of promelittin are found to insert into the membrane.

Intramembrane molecular dipoles affect the membrane insertion and folding of a model amphiphilic peptide

The relationship between the dipole potential and the interaction of the mitochondrial amphipathic signal sequence known as p25 with model membranes has been studied using 1-(3-sulfonatopropyl)-4-[beta[2-(di-n-octyl-amino)-6-naphthyl]viny l] pyridinium betaine (di-8-ANEPPS) as a fluorescent probe. The dipole potential of phosphatidylcholine membranes was modified by incorporating into the bilayer the sterols phloretin and 6-ketocholestanol (KC), which decrease and increase the dipole potential, respectively. The results derived from the application of a dual-wavelength ratiometric fluorescence method for following the variation of the membrane dipole potential have shown that when p25 inserts into the lipidic bilayer, a decrease in the dipole potential takes place. The magnitude of this decrease depends on the initial value of the dipole potential, i.e., before interaction with the peptide. Thus, when KC was incorporated into the bilayer, the decrease caused by the membrane insertion of p25 was larger than that caused in PC membranes. Alternatively, in the presence of phloretin, the decrease in the potential caused by the peptide insertion was smaller. Complementary studies involving attenuated total reflectance-Fourier transform infrared spectroscopy of the peptide membrane interactions have shown that modification of the dipole potential affects the conformation of the peptide during the course of its interaction with the membrane. The presence of KC induces a higher amount of helicoidal structure. The presence of phloretin, however, does not appear to affect the secondary structure of the peptide. The differences observed in the dipole potential decreases caused by the presence of the peptide with the PC membranes and phloretin-PC membranes, therefore, must involve differences in the tertiary and, perhaps, quaternary conformations of p25.

Pathology of mucormycosis of cane toads in Australia

The gross and microscopic pathology of a fungal septicaemia caused by the zygomycete. Mucor amphibiorum in 27 free-ranging cane toads, Bufo marinus, in Australia is described. Seven of the 27 toads had clinical signs of illness when discovered and five of these seven were moribund. Multiple granulomas were found in many organs, and in massive infections granulomas tended to coalesce. Liver, spleen, kidneys, urinary bladder, heart and lung were most commonly involved, but granulomas also occurred in subcutaneous lymph spaces, skin, gastro-intestinal tract, voluntary muscle, bone, cranial cavity and the oral cavity. Single lesions appeared grossly as a lemon coloured nodule < or = 5 mm in diameter. Histologically, the primary lesion was a granuloma composed of multinucleate giant cells, macrophages, occasional lymphocytes and eosinophils surrounding the distinctive sphaerules of M. amphibiorum. Fibroblasts occurred in greater numbers at the periphery and collagen formed a dense fibrous capsule around some nodules. A less common lesion resembled a microabscess and consisted of mononuclear cells, neutrophils and eosinophils surrounded by macrophages. Many of the centrally placed mixed inflammatory cells appeared necrotic. This reaction appeared to be more acute. Both types of lesions sometimes occurred concurrently, but the latter was less common. The pattern of lesions and natural history of M. amphibiorum suggested that ingestion of contaminated soil may have been the route of infection.

Time resolution of binding and membrane insertion of a mitochondrial signal peptide: correlation with structural changes and evidence for cooperativity

Utilizing a recently developed novel fluorescence technique [Wall et al. (1995) Mol. Membr. Biol. 12, 183-192], it is shown that the interactions of p25, the leader peptide of subunit IV of cytochrome c oxidase, with phospholipid membranes can be identified in real time. p25 is observed to bind following stopped-flow mixing of the peptide with phospholipid membranes with rate constants up to about 700 s-1 and then insert into the membrane with rate constants on the order of 0.4 s-1. Comparison of these processes with similarly time-resolved experiments performed with a stopped-flow CD spectrometer revealed that p25 does not become alpha-helical upon binding to the membrane. Following membrane insertion, however, p25 was observed to adopt an alpha-helical configuration. The temperature dependency of these processes was then found to yield activation energies for the respective components of the p25-membrane interaction.

Fibromatoses of childhood: the spectrum of radiographic findings

Fibrous tumor of childhood include several disorders with variable biologic behavior. In the review by Coffin and Dehner [1] of 190 soft-tissue neoplasms in 183 children, 27% were fibroblastic or myofibroblastic in origin. Although nearly all fibrous lesions are benign, they may be locally aggressive. The purpose of this essay is to describe clinical characteristics and to illustrate radiologic features of commonly encountered fibrous lesions of childhood. Familiarity with the presentation and variable appearance may aid the radiologist in suggesting the diagnosis of fibromatosis.

Interactions of macromolecules with the mammalian cell surface

The characterisation of fluoresceinphosphatidylethanolamine (FPE) as a real-time indicator of the electrostatic nature of the cell membrane surface is described. The conditions appropriate for the labelling of cell membranes and the implementation of FPE as a tool to monitor the interactions of various proteins and peptides with membranes are outlined. Some complications attributed to the erythrocyte glycocalyx are examined. In addition it is shown using neuraminidase as an example, that some types of enzyme-catalysed reactions on the cell surface may be monitored in real time. It is also shown that information concerning the binding of several proteins such as serum albumin and monoclonal antibodies are accessible with this technique. The albumin in particular is shown to exhibit a saturation of binding, the analysis of which indicates that the dissociation constant for erythrocytes was determined to be 8 microM and for lymphocytes to be almost 3 microM. On the basis of this comparison together with artificial membranes, the membrane protein components of the lymphocyte surface are implicated in the binding of albumin or the erythrocyte membrane proteins reduce the affinity of the cell surface for albumin.

The use of fluoresceinphosphatidylethanolamine (FPE) as a real-time probe for peptide-membrane interactions

The characterization of fluoresceinphosphatidylethanolamine (FPE) as a real-time indicator of the electrostatic nature of a membrane surface is described. The conditions appropriate for the labelling of membranes and the implementation of FPE as a tool to monitor the interactions of various peptides with model membranes are outlined. It is shown that of the membrane-active peptides studied, Naja naja kaouthia cardiotoxin and pyrularia thionin bind to certain model membranes without insertion. Whereas the leader sequence of the nuclear encoded subunit IV of mammalian cytochrome c oxidase (E.C. 1.9.3.1), known as p-25, and melittin appear to bind and then partially insert into the membrane. It seems evident also that melittin does not adopt a fully transmembrane configuration. Melittin is known to promote membrane lysis and by employing a rapid-kinetic technique it is shown that the time-course of such lysis does not appear to correlate with peptide binding, but following binding a significant proportion of melittin must become inserted into the membrane before lysis appears to commence.

Serum neuron-specific enolase and immunohistochemical markers of neuroendocrine differentiation in lung cancer

An enzyme immunoassay for serum neuron-specific enolase (NSE) was evaluated with respect to analytical performance and clinical utility and compared with immunohistochemical evaluation of neuroendocrine differentiation. Values obtained agreed well with values obtained using a radioimmunoassay method giving a correlation coefficient of 0.934. Analytical performance of the enzyme immunoassay was good but the diagnostic sensitivity of 82% in extensive and 67% in limited disease was insufficient for serum NSE to be of value in the diagnosis of small cell lung cancer (SCLC). Serum NSE decreased significantly in 11 of 15 patients with SCLC following institution of chemotherapy. Classification of lung cancers into SCLC and non small cell lung cancer (NSCLC) types is largely based on tumour morphology. Neuroendocrine differentiation may not be morphologically evident. Immunohistochemical staining of tumour tissue with markers of neuroendocrine differentiation, i.e. NSE (both monoclonal and polyclonal antibodies) Leu 7, Chromogranin A and P G P 9.5 was performed in both patients with SCLC and NSCLC. 38 per cent of patients with NSCLC had both raised serum NSE and positive NSE (polyclonal) immunoperoxidase staining of lung tissue. A further 35 per cent of patients showed a raised serum NSE or positive immunohistochemistry but not both. The presence of two positive immunoperoxidase markers in lung tissue has been suggested as an indicator of responsiveness to chemotherapy in NSCLC patients. A number of factors may affect immunohistochemical positivity in tissue sections and the additional use of a serum marker may better define chemotherapy responsive groups.

Mucor amphibiorum in the toad, Bufo marinus, in Australia

Mucor amphibiorum, a fungus previously found in captive amphibians in Europe and the platypus in Australia, was observed in free-ranging toads, Bufo marinus, in Australia. In tissues the fungus occurred as sphaerules 4.9 to 36.4 microns in diameter; hyphae were not formed. Some spharules developed two to 11 daughter sphaerules internally and these were released into tissues by dissolution of the outer wall. Infected toads were found at 11 sites from nine locations in northern and eastern Australia. The overall prevalence of infection in 3,518 toads was 0.71%. Mucor amphibiorum was isolated from soil at one location.

Minimal residual disease after allogeneic bone marrow transplantation for chronic myeloid leukaemia in first chronic phase: correlations with acute graft-versus-host disease and relapse

We have studied 61 patients who underwent allogeneic bone marrow transplantation (BMT) for chronic myeloid leukaemia (CML) in first chronic phase. Minimal residual disease was detected by the amplification of the leukaemia-specific BCR-ABL fusion mRNA with the polymerase chain reaction (PCR) using a highly sensitive nested primer strategy. As a general pattern, patients often had detectable BCR-ABL (PCR positive) for up to 6 or 9 months post BMT after which time BCR-ABL became undetectable (PCR negative). The conversion from PCR positive to PCR negative was not associated with the time at which cyclosporin A treatment was stopped. Six patients (10%) have relapsed during the period of this study, two within 1 year and four more than 1 year after transplant. The relationship between PCR positivity more than 1 year post transplant and relapse was significant (P = 0.036) but 15 patients who were PCR positive beyond 1 year remain in complete clinical and cytogenetic remission. Thus late positivity identifies a group of patients at increased risk of relapse but is of little predictive value for individual patients. Of the four late relapses, two had been persistently PCR positive and two were initially PCR positive, converted to negative and subsequently to positive again. Although all relapses were preceded by PCR positivity, relapse may occur only 12 months after a PCR negative result. The proportion of patients PCR negative at 3/4 months after BMT was found to increase significantly with the severity of acute GVHD (P = 0.002) but no relationship was found between acute GVHD and subsequent PCR results. There was no clear association between severity of chronic GVHD and PCR result.

Dysplasia of the corpus callosum in identical twins with nonketotic hyperglycinemia

Nonketotic hyperglycinemia (NKH) is an autosomal recessively inherited disorder of the glycine degradation pathway leading to accumulation of glycine in body fluids and tissues. Identical twins with nonketotic hyperglycinemia and dysplasia of the corpus callosum are described in support of the hypothesis that some patients with NKH have a genetic defect of the glycine degradation pathway resulting in abnormal corpus callosal development. It is important to screen for metabolic defects whenever similar structural defects are present.

Cardiomyopathy and myocyte intranuclear inclusions in neuronal intranuclear inclusion disease: a case report

Neuronal intranuclear inclusion disease (NIID) is a progressive, usually fatal degenerative neurologic condition characterized by eosinophilic, intranuclear inclusions in neurons of the central and peripheral nervous system. We report a boy with onset of disease manifestations at age 3 and death at age 9, who showed clinical and pathologic findings characteristic of NIID. The case is unique because of cardiomyopathy manifested 1 year prior to death. Postmortem findings confirmed the presence of cardiomyopathy and revealed intranuclear inclusions in myocytes. Neither nuclear inclusions in the myocardium nor cardiac involvement have previously been reported in NIID.

A physiological comparison of the short-leg walking cast and an ankle-foot orthosis walker following 6 weeks of immobilization

Iatrogenically induced weakness, stiffness, and functional impairment associated with classical methods of short-leg cast immobilization have long been recognized. This study compares the effects of "controlled" immobilization with an ankle-foot orthosis (AFO) and short-leg cast (SLC) immobilization for 6 weeks. A significant reduction in loss of range of motion, muscular strength, and muscular atrophy, ie, functional impairment, at the time of cessation of immobilization was noted when an AFO was used. The additional advantages of an AFO are the elimination of multiple cast changes including economic benefits, ease in the assessment of functional improvement during treatment, and convenient adjustment for swelling and atrophy.

Prevention of tubercidin host toxicity by nitrobenzylthioinosine 5'-monophosphate for the treatment of schistosomiasis

Host toxicity of the dose regimen of tubercidin (7-deazaadenosine) plus nitrobenzylthioinosine 5'-monophosphate (NBMPR-P) used in combination therapy of schistosomiasis (M. H. el Kouni, D. Diop, and S. Cha, Proc. Natl. Acad. Sci. USA 80:6667-6670, 1983; M. H. el Kouni, N. J. Messier, and S. Cha, Biochem. Pharmacol. 36:3815-3821, 1987) was examined in vivo in mice and in vitro with human bone marrow progenitor cells. Four successive daily intraperitoneal injections of tubercidin at 5 mg/kg per day produced 100% mortality in mice within 3 to 5 days following the first injection, with massive peritonitis and intestinal obstruction secondary to abdominal adhesions. Coadministration of NBMPR-P (25 mg/kg per day) protected the mice from the lethality of tubercidin and allowed the repetition of the regimen for a second time with 100% survival until the mice were sacrificed 22 days following the first injection. Blood chemistry, hematological studies, and histological examinations showed no evidence for injury to the liver, kidney, spleen, pancreas, mesentery, or peritoneal mesothelium. In vitro, tubercidin alone had a direct dose-dependent inhibitory effect on myeloid and erythroid human bone marrow progenitor cells, and consistent inhibition (50%) of granulocyte-macrophage CFU (CFU-GM) and erythroid burst-forming units (BFU-E) occurred at 2 to 3 nM tubercidin. At higher doses, BFU-E were more sensitive to tubercidin toxicity than CFU-GM. Complete inhibition (99%) of BFU-E colonies occurred at 10 nM tubercidin, while complete inhibition of CFU-GM occurred at 100 nM. NBMPR-P at 10 to 100 nM protected CFU-GM and BFU-E from tubercidin toxicity in a dose-dependent matter.