Unravelling the riddle of Radix: DNA barcoding for species identification of freshwater snail intermediate hosts of zoonotic digeneans and estimating their inter-population evolutionary relationships

Radix spp. are intermediate host snails for digenean parasites of medical and veterinary importance. Within this genus, species differentiation using shell and internal organ morphology can result in erroneous species identification, causing problems when trying to understand the population biology of Radix. In the present study, DNA barcoding, using cox1 and ITS2 sequences, identified populations of Radix auricularia and Radix balthica from specimens originally morphologically identified as Radix peregra from the UK. Assessment of cox1 and ITS2 as species identification markers showed that, although both markers differentiated species, cox1 possessed greater molecular diversity and higher phylogenetic resolution. Cox1 also proved useful for gaining insights into the evolutionary relationships of Radix species populations. Phylogenetic analysis and haplotype networks of cox1 indicated that R. auricularia appeared to have invaded the UK several times; some haplotypes forming a distinct UK specific clade, whilst others are more akin to those found on mainland Europe. This was in contrast to relationships between R. balthica populations, which had low molecular diversity and no distinct UK specific haplotypes, suggesting recent and multiple invasions from mainland Europe. Molecular techniques therefore appear to be crucial for distinguishing Radix spp., particularly using cox1. This barcoding marker also enables the population biology of Radix spp. to be explored, and is invaluable for monitoring the epidemiology of fluke diseases especially in the light of emerging diseases and food security.

Identification of a major causative agent of human cercarial dermatitis, Trichobilharzia franki (Müller and Kimmig 1994), in southern England and its evolutionary relationships with other European populations

Background

Trichobilharzia is the most species rich and widely distributed genus of schistosomes and is known throughout Europe and North America as an agent of human cercarial dermatitis. The disease is caused by an acute allergic reaction in the skin that develops as a consequence of repeated contact with water containing schistosomatid cercariae. However, despite historical outbreaks of the disease, there are no published records of accurately identified Trichobilharzia species from the UK.

Methods

Two hundred Radix auricularia (L.) were sampled from a recreational fishing lake in Hampshire and emerging schistosomatid cercariae were collected for microscopy and DNA extraction. General morphological description of the cercariae was performed, alongside sequencing and phylogenetic analysis of the 28S ribosomal DNA for accurate species identification as well as comparisons of ITS1 in order to identify evolutionary affinities with other European populations. All molecular comparisons were performed using published sequences.

Results

The phylogenetic analysis of 28S sequences identified the cercariae as Trichobilharzia franki. Two unique British ITS1 haplotypes were identified which were most closely related to haplotypes of T. franki populations from France. Haplotype network analysis indicated the mixing of T. franki populations throughout Europe. It is suggested that parasite distribution is the probable result of the movement of migratory waterfowl.

Conclusions

This is the first accurate record of T. franki in the UK. The movement of T. franki with waterfowl could pose a considerable human health risk, as in mainland Europe, and signifies T. franki-associated human cercarial dermatitis as a re-emerging disease in the UK.

Potential environmental and host gender influences on prevalence of Haemogregarina platessae (Adeleorina:Haemogregarinidae) and suspected Haemohormidium terraenovae (incertae sedis) in Brazilian flounder from the Patos Lagoon Estuary, southern Brazil

Flounder, Paralichthys orbignyanus (Valenciennes), were captured in polluted and non-polluted sites within the Patos Lagoon Estuary, southern Brazil, over four seasons. Blood films showed a high prevalence of infection with a haemogregarine, or mixed parasitaemias of this and an organism resembling Haemohormidium terraenovae So, 1972. Haemogregarine gamont stages conformed to existing descriptions of Desseria platessae (Lebailly, 1904) Siddall, 1995 from flatfishes, but intraerythrocytic division of meronts was observed, leading to the recommendation for nomenclatural correction, placing the haemogregarine in the genus Haemogregarina (sensu lato) Danilewsky, 1885. Statistical analyses suggested that although sample sizes were small, infections with meront stages, immature and mature gamonts were all influenced by site, and possibly therefore, by pollution. Season also appeared to determine likelihood of infection with meronts and immature gamonts, but not mature gamonts, while adult fish gender apparently affected infection with immature and mature gamonts, but not meronts. The H. terraenovae-like organism exhibited unusual extracellular forms and did not match closely with the type description of H. terraenovae; precise identification was therefore difficult. Data analyses suggested that parasitism by this organism was influenced by site and fish gender, since females and males from non-polluted water were infected, but only females from the polluted site. Season was also important and significantly more adult fish of both sexes were infected with this parasite in the Brazilian summer and autumn, compared with winter and spring. Finally, these appeared to be the first observations of Haemogregarina platessae, and possibly H. terraenovae, from the southern hemisphere.

Integrin engagement modulates the phosphorylation of focal adhesion kinase, phagocytosis, and cell spreading in molluscan defence cells

Integrins play a key role in cellular immune responses in a variety of organisms; however, knowledge of integrins and their effects on cell signalling and functional responses in molluscan defence reactions is poor. Using integrin-mediated cell adhesion kits, alphaVbeta3 and beta1 integrin-like subunits were identified on the surface of Lymnaea stagnalis haemocytes. Haemocyte binding via these integrins was found to be dependent on Ca2+/Mg2+. Western blotting with an anti-phospho (anti-active) focal adhesion kinase (FAK) antibody revealed a 120-125 kDa FAK-like protein in these cells; this protein was transiently phosphorylated upon haemocyte adhesion over 90 min, with maximal phosphorylation occurring after 30 min binding. Also, integrin engagement with the tetrapeptide Arg-Gly-Asp-Ser (RGDS) resulted in a rapid increase in phosphorylation of the FAK-like protein; however, RGDS did not affect the phosphorylation of extracellular signal-regulated kinase. Treatment of haemocytes with RGDS (2 mM) inhibited phagocytosis of E. coli bioparticles by 88%. Moreover, at this concentration, RGDS reduced cell spreading by 61%; stress fiber formation was also impaired. Taken together, these results demonstrate a role for integrins in L. stagnalis haemocyte adhesion and defence reactions and, for the first time, link integrin engagement to FAK activation in molluscs.

The use of an alternative food source (red clover) as a means of reducing slug pest damage to winter wheat: towards field implementation

Slugs are major pests of many crops in the UK, including winter wheat, yet current methods of control are often unreliable. The aim of this study was to investigate three issues key to the successful field implementation of a control strategy that uses red clover as an alternative food source to reduce the amount of damage caused to winter wheat by the field slug, Deroceras reticulatum (Müller). A series of three experiments was designed to assess this aim. Firstly, under laboratory conditions, red clover was consumed in greater quantities than wheat, even when wheat was presented as a novel food. Secondly, red clover had no significant effects on the emergence and early growth of wheat in a polytunnel experiment. Both these results are crucial to the successful implementation of a strategy that uses red clover as an alternative food source. Lastly, the results of a field experiment were consistent with the results of the polytunnel experiment, in that red clover did not significantly affect wheat emergence. However, plots in which red clover was left to grow until the time of wheat harvest resulted in significantly lower (43%) wheat yields than plots without red clover. These results suggest that red clover must be removed from the field after the wheat has passed its vulnerable seedling stage. Recommendations for the potential use of red clover as an alternative food source for reducing damage to winter wheat in field conditions are discussed and opportunities for further work are suggested.

Phagocytosis by Lymnaea stagnalis haemocytes: A potential role for phosphatidylinositol 3-kinase but not protein kinase A

The molecular events that regulate phagocytosis, an important innate immune response, in invertebrate defence cells (haemocytes) are poorly understood. Lymnaea stagnalis haemocytes were used as a model to elucidate the role of cell signalling pathways in phagocytosis by molluscan defence cells. The phosphatidylinositol 3-kinase (PI3-K) inhibitor, LY294002, significantly impaired haemocyte phagocytic activity in a dose-responsive manner with 10 microM LY294002 reducing internalization of fluorescent-conjugated Escherichia coli by 62% (P < or = 0.001). In contrast, the protein kinase A (PKA) inhibitor KT5720 was without effect. Therefore, PI3-K, but not PKA, appears to control phagocytosis by haemocytes in these gastropod molluscs.

A laboratory-based comparison of a molluscicide and an alternative food source (red clover) as means of reducing slug damage to winter wheat

Slugs are major pests of many crops in the UK, including winter wheat, yet current methods of control are often unreliable. This study investigates the potential use of red clover, as an alternative food source, to reduce the amount of damage caused to winter wheat by the field slug, Deroceras reticulatum (Müller). Two laboratory-based studies, each conducted over a 7-day period, investigated the effects of red clover seedlings and commercial metaldehyde pellets on damage to winter wheat seeds and seedlings. The results indicate that metaldehyde applications, in the form of commercially available pellets, resulted in significantly greater protection to wheat seeds compared with red clover, whereas metaldehyde and red clover were equally as effective in reducing damage to wheat seedlings. A further laboratory experiment investigated the effect of two slug population densities (48 and 16 adults m(-2)) and high and low red clover seed rates (125% and 75% of a standard rate) on damage to wheat seeds. Results showed that, at the highest slug population density, red clover sown at 125% of the standard rate gave 99% protection to wheat seeds, compared with the 75% seed rate which gave 55%. At the lower slug population density, both seed rates of red clover resulted in similar levels of protection. Implications for the potential use of red clover as an alternative food source for reducing damage to winter wheat in field conditions are discussed.

Carbohydrates that mimic schistosome surface coat components affect ERK and PKC signalling in Lymnaea stagnalis haemocytes

Molluscs are intermediate hosts for helminth parasites such as Schistosoma spp. that possess an immunogenic surface coat of high carbohydrate content, with fucose as the predominant saccharide. More than a decade ago, it was postulated that such components could block receptors on snail haemocytes thus preventing recognition of intra-molluscan schistosome stages. Although more recent studies have shown that carbohydrates can suppress processes such as phagocytosis by haemocytes, interference of the haemocyte cell signalling pathways that regulate immunity by saccharides has not yet been investigated. We have recently reported the presence of extracellular-signal regulated kinase and protein kinase C in Lymnaea stagnalis haemocytes. Here we show that extracellular-signal regulated kinase and protein kinase C activities are down-regulated when haemocytes are exposed to albumin-linked fucose and galactose in the absence of haemolymph. Moreover, we demonstrate that phagocytosis is reduced under these conditions. Interestingly, in the presence of haemolymph, only protein kinase C activity is down-regulated and only galactose suppresses phagocytosis, implying a role for serum factors in the preservation of haemocyte function following exposure. We therefore propose that the establishment of a compatible relationship between a schistosome and its snail host is at least in part due to down-regulation of cell signalling events in haemocytes.

Activation of extracellular-signal regulated kinase is required for phagocytosis by Lymnaea stagnalis haemocytes

Haemocytes are the primary defence cells of molluscs. In the present study, extracellular-signal regulated kinase (ERK) 1/2-like proteins were identified within Lymnaea stagnalis haemocytes, with apparent molecular weights of 44 and 43 kDa, respectively. Mitogen-activated protein kinase (MAPK) activity assays have confirmed that the L. stagnalis ERK possesses kinase activity towards Elk-1. Challenge of haemocytes with bacterial lipopolysaccharide (LPS) resulted in a transient activation of ERK, and immunocytochemistry revealed that phospho-ERK was present in both the perinuclear region and the nucleus following challenge. MAPK/ERK kinase (MEK) inhibitors blocked ERK activation confirming that MEK lies upstream of ERK in haemocytes. Moreover, phagocytosis assays, using various inhibitors, showed that ERK activity was vital for efficient phagocytosis and that ERK may be activated by both Ras-dependent and Ras-independent mechanisms. Overall, this study has furthered knowledge of ERK signalling in molluscan immunity and has shown that the ERK pathway regulates the phagocytic activity of molluscan haemocytes.

The tolerance of the field slug Deroceras reticulatum to freezing temperatures

Cold hardiness of ectotherms has been widely studied in arthropods, but there is a more limited literature on the survival of molluscs at low temperatures. A number of intertidal species have been examined in detail, but terrestrial molluscs have largely been overlooked until recently. This paper reports results of laboratory experiments to evaluate the cold hardiness of the terrestrial slug, Deroceras reticulatum. The mean supercooling point (SCP) rose from -4.2 degree C in summer to -3.6 degree C in winter. The SCP that caused 50 percent mortality (LSCP50) remained constant at -4.7 to -4.8 degree C in both seasons, but slugs were able to survive the frozen state for longer in winter (LD50 of 31.8 minutes compared with 17.0 minutes in summer). Slug survival at freezing temperatures was prolonged to at least five hours when placed on a moist, absorbent substrate. D. reticulatum exhibits partial freeze tolerance, with an increased survival in winter. The results are discussed in relation to the natural environment of slugs.

A laboratory evaluation of the palatability of legumes to the field slug, Deroceras reticulatum Müller

Slugs are major pests of many crops, including winter wheat, in temperate climates, yet current methods of control are often unreliable. The aim of this study is to investigate the potential for common legume species to act as an alternative source of food, or trap crop, for the most damaging agricultural pest species, the grey field slug, Deroceras reticulatum Müller, thereby reducing damage to the wheat crop. A series of three controlled-environment experiments were designed to assess this aim. Individual slugs were fed leaves of one of ten legume species together with winter wheat leaves for a 72-h period. A clear hierarchy of acceptability was shown, with red clover, lucerne, lupin and white clover showing significantly higher Acceptability Indices than the other six species tested. Red clover produced the greatest reduction in mean wheat consumption (78%) from day 1 to day 3. When species were fed individually, red clover was consumed in significantly greater quantities than any of the other treatments: 40% more than white clover and 56% more than wheat. Furthermore, when fed with red clover the amount of wheat consumed was some 50% less than when the latter was fed alone. The results indicate that legumes vary greatly in their acceptability to D. reticulatum and it is essential that a legume with a high Acceptability Index is chosen, which results in the least amount of wheat consumed.

An integrated pharmacodynamic analysis of erythropoietin, reticulocyte, and hemoglobin responses in acute anemia

PURPOSE

To determine by pharmacodynamic (PD) analysis physiologically relevant parameters of the cellular kinetics of erythropoiesis in acute anemia.

METHODS

The PD relationships among erythropoietin (EPO), reticulocyte, and RBC (Hb) responses were investigated in young adult sheep in acute anemia induced twice by two controlled phlebotomies separated by a 4-week recovery period.

RESULTS

The phlebotomies resulted in rapid increases in plasma EPO, with maximal levels occurring at 3 to 8 days, followed by a reticulocyte response with a delay of 0.5 to 1.5 days. The Hb returned to prephlebotomy base line at the end of the 4-week recovery period. The EPO, reticulocyte count, and Hb responses were well described by a PK/PD model (r = 0.975) with the following cellular kinetics parameters: the lag time between EPO activation of erythroid progenitor cells and reticulocyte formation; the reticulocyte-to-RBC maturation time; the reticulocyte and Hb formation efficacy coefficients, quantifying EPO's efficacy in stimulating the formation of reticulocytes and Hb, respectively; the C50 PK/PD transduction parameter defined as the EPO level resulting in half the maximum rate of erythropoiesis.

CONCLUSION

Physiologically relevant cellular kinetics parameters can be obtained by an endogenous PK/PD analysis of phlebotomy data and are useful for elucidating the pathophysiologic etiology of various anemias.

TH1 cytokine response of CD57+ T-cell subsets in healthy controls and patients with alcoholic liver disease

Patients with chronic inflammatory diseases, including Crohn's disease and rheumatoid arthritis, as well as those with certain viral infections, and patients who are transplant recipients or who have certain hematologic malignancies have been observed to have CD57+ T cell expansion in both CD4+ and CD8+ subsets. We have reported previously that alcoholic patients also have CD57+ T cell expansion. Because many alcoholics become seriously deficient in cell-mediated immunity, it is of interest to determine whether the expanded CD57+ subsets can respond to stimulation with normal T helper cell subtype 1 (TH1) cytokine production. We report evaluation of the CD57 T-cell subsets of patients with alcoholic liver disease (ALD) with the use of cytoplasmic staining after stimulation through the T-cell receptor (TCR). The CD57+ subsets of the T cells of both healthy individuals and patients with ALD express significantly higher amounts of cytoplasmic tumor necrosis factor-alpha (TNF-) and interferon-gamma (IFN-) after 6 h of stimulation than do the CD57- subsets. This increased production can persist up to 46 h of continuous stimulation. Under these assay conditions, very little cytoplasmic interleukin (IL)-4 is observed in the T cells of either healthy control subjects or patients with ALD. Measurement of cytokine secretion by sort-purified CD57 T-cell subsets with the use of enzyme-linked immunosorbent assay (ELISA) shows that the CD57+ T-cell subset produces 18- to 30-fold more TNF- and IFN-, respectively, than does the CD57- subset in the first 12 h of stimulation. This response requires only stimulation through the TCR for the CD57+ subset, whereas significant secretion by the CD57- subset requires added IL-2 or anti-CD28 antibody. These results are consistent with the concept of the CD57+ T-cell subset as a differentiated effector cell and demonstrate that patients with ALD who are not drinking at the time of evaluation have normal or increased immediate TH1 T-cell responses.

The influence of nutritional status on the feeding behaviour of the field slug, Deroceras reticulatum (Müller)

The field slug, Deroceras reticulatum, a common pest of agricultural and horticultural crops, is a generalist herbivore with distinct preferences for particular food items. However, these preferences are not fixed, but are influenced by the recent dietary history of the slugs. In particular, slugs tend to select novel food items ('neophilia'). We investigated the basis of such influences, using artificial diets in which protein and carbohydrate composition could be controlled and non-nutritional ('secondary') chemicals added as flavours. The slugs showed no general inclination for neophilia based on taste alone. There was a possible learned association between protein content and taste, but this was weakly expressed. However, the slugs selected food items, when given a choice, containing nutrients that were deficient in earlier diets, even though all the food items contained the same familiar secondary taste chemicals. Injections of missing nutrients into the haemocoel of slugs inhibited such changes in food preference, indicating that slugs' feeding preferences are influenced directly by their internal nutritional status. We suggest that neophilia in D. reticulatum is a physiological response to a nutritional imbalance arising from a suboptimal diet. Copyright 2000 The Association for the Study of Animal Behaviour.

Ethanol induces cell death and cell cycle delay in cultures of pheochromocytoma PC12 cells

Animal models have clearly established that ethanol exposure can deplete neurons in the developing nervous system. However, the mechanism by which ethanol reduces cell number is unclear. In our study, cultures of pheochromocytoma cells, a neuronal-like cell line, were maintained in media, which supported cell proliferation. Although cell numbers continued to increase in the presence of ethanol, this increase was partially inhibited by ethanol exposure. This inhibitory effect was concentration and duration dependent. Cell proliferation was still partially inhibited after removal of ethanol, but this inhibition was temporary and disappeared after a 24-hr recovery period in ethanol-free conditions. Further study indicated that ethanol partially inhibited the increase in cell numbers by two mechanisms: (1) studies with vital stains indicated that ethanol induced cell death; (2) experiments using synchronized pheochromocytoma cell cultures showed that ethanol can induce cell cycle delay, thereby lengthening the doubling time of the cells. Analysis by flow cytometry indicated that with ethanol exposure, the cells accumulated in the G1 phase of the cell cycle. Our results suggest that in the developing nervous system, ethanol may limit the numbers of proliferating, neuronal precursor cells by two simultaneous mechanisms, cell death and cell cycle delay.

Alcohol abuse, alcoholism, and damage to the immune system--a review

Chronic alcohol abuse exacts a major social and medical toll in the United States and other Western countries. One of the least appreciated medical complications of alcohol abuse is altered immune regulation leading to immunodeficiency and autoimmunity. The consequences of the immunodeficiency include increased susceptibility to bacterial pneumonia, tuberculosis, and other infectious diseases. In addition, the chronic alcoholic often has circulating autoantibodies, and recent investigations indicate that the most destructive complications of alcoholism, such as liver disease and liver failure, may have a component of autoimmunity. Current research on altered cytokine balance produced by alcohol is leading to new insights on the regulation of the immune system in the chronic alcoholic. There is also recent development of exciting new techniques designed to improve or restore immune function by manipulation of cytokine balance. Although much remains to be learned, both in the abnormalities produced by alcohol and in the techniques to reverse those abnormalities, current progress reflects a rapidly improving understanding of the basic immune disorders of the alcoholic.

Ethanol and natural killer cells. I. Activity and immunophenotype in alcoholic humans

The human lymphocyte fraction with the greatest fresh killing activity against K562 targets is phenotypically the CD3-CD19-CD56+ subset. There have been reports of reduced natural killer (NK) activity in human alcoholics, but overall consistency is lacking and phenotypic monitoring has been inadequate to allow reliable estimates of changes in the active cell fractions. We have evaluated a range of cell surface markers and fresh NK activity in controls and alcoholics, and now report abnormalities in both phenotype and function in some alcoholics, but a normal profile in others. Patients without evidence of active liver disease (AWLDs) tend to have normal fresh basal activities and phenotypic profiles. Patients with alcoholic liver disease (ALDs) have fewer Lin- lymphocytes that are CD56+. Three of 14 ALDs assayed in the present work had absent NK activity, whereas others were activated. In normal controls and in AWLDs, the presence of monocytes in the lytic assay consistently inhibits lysis; but, in some patients with ALD, the presence of monocytes is stimulatory to NK activity. In alcoholics as one group, there is a statistically significant relative increase in a novel Lin- subset of unknown function; this subset has a phenotype of Lin-CD56-CD45RO+.

Ethanol and natural killer cells. II. Stimulation of human natural killer activity by ethanol in vitro

A single ethanol ingestion of 1 g/kg by healthy individuals under controlled conditions does not inhibit and may stimulate fresh natural killer (NK) activity measured 16 hr later. However, ethanol inhibits fresh human NK activity when added to the lytic assay medium, as reported previously by other investigators. In contrast, using the same target (K562 erythroleukemia cells), peripheral blood mononuclear cells cultured 3 days with 50 units/ml of interleukin-2 are no longer inhibited significantly by the same concentration of ethanol that inhibited the fresh cells by 80%. When freshly isolated peripheral blood mononuclear cells, monocyte-depleted lymphocytes, or partially purified NK cells are pre-exposed to ethanol in vitro for 1 to 7 days, washed, and assayed for lytic activity against K562, the lytic activity is increased compared with nonethanol-exposed cells incubated concurrently. This increase is not dependent on accessory cells, added cytokines, or cell growth, and seems to be an intrinsic response of the NK subset to ethanol exposure. The finding of NK stimulation by ethanol, considered together with the observation of NK cell loss in some chronic alcoholics, suggests that loss of NK activity in the chronic alcoholic may result from cell loss rather than direct ethanol inhibition of NK activity.

Effect of a single ethanol exposure on HIV replication in human lymphocytes

BACKGROUND

Alcoholism is known to cause perturbations in cellular and humoral immunity, and some data suggest that acute alcohol ingestion enhances HIV replication in the lymphocytes of drinkers.

METHODS

To study the acute effects of alcohol ingestion on HIV replication, oral ethanol (1 g/kg) was administered to 12 healthy volunteers in a controlled clinical setting. In vitro replication of HIV in the subjects' cultured lymphocytes and changes in lymphocyte phenotypes were evaluated.

RESULTS

Statistically significant increases in peripheral lymphocytes and natural killer cell numbers were identified after the initial ethanol trial. HIV replication also increased in the isolated lymphocytes of some subjects after ethanol ingestion, but most subjects in the second trial showed essentially no changes in any of these parameters.

CONCLUSIONS

Our results are consistent with either a subtle, study-induced stress-related enhancement in HIV replication or significant individual variation in response to ethanol. The results do not provide evidence for a general increase in HIV replication in the lymphocytes of subjects following a single in vivo ethanol dose of 1 g/kg.

The use of the Beck Airway Airflow Monitor for verifying intratracheal endotracheal tube placement in patients in the pediatric emergency department and intensive care unit

Traditional methods of confirming that the endotracheal tube is in the trachea are often unavailable or difficult to perform in some clinical situations, such as interfacility transport or other times outside the neonatal intensive care unit. We evaluated the Beck Airway Airflow Monitor (BAAM), through which airflow makes a whistling sound, for its safety and efficacy in neonates. We studied 46 neonates ranging in weight from 0.6 to 3.7 kg. We found that the BAAM consistently produced the desired whistling sound signaling intratracheal placement of the endotracheal tube in all infants weighing above 1.5 kg. No adverse effects or complications were noted. The results support the safety and efficacy of the BAAM in confirming intratracheal endotracheal tube position in neonates.

Noncompliance with scheduled revisits to a pediatric emergency department

OBJECTIVES

To determine the incidence of, the risk factors associated with, and the consequences of noncompliance (NC) with a scheduled revisit to a pediatric emergency department (ED).

DESIGN

A prospective, inceptive cohort study.

SETTING

An urban pediatric ED.

PATIENTS

A sample of 179 children.

INTERVENTIONS

Interviews of parents and physicians.

RESULTS

Overall, 91 (51%) of the parents were noncompliant, and just 21% were noncompliant because "the child was better." Of the 124 patients who ED physicians believed were "certain to return," 57 (46%) were noncompliant. Six factors were associated with NC: (1) the parent believed that the child was not severely ill (relative risk [RR], 2.92; 95% confidence interval [CI], 1.31-6.49); (2) the parent was judged to be unable to recognize a clinical deterioration of the child (RR, 1.95; 95% CI, 1.55-2.45); (3) the parent did not own a car (RR, 1.77; 95% CI, 1.23-2.54); (4) the parent was younger than 21 years (RR, 1.48; 95% CI, 1.12-1.95); (5) no laboratory testing was performed during the initial ED visit (RR, 1.36; 95% CI, 1.03-1.80); and (6) the parent was judged "not certain" to return (RR, 1.34; 95% CI, 1.01-1.78).

CONCLUSIONS

The high rate and the lack of predictability of NC with a scheduled revisit to an ED should influence patient disposition decisions. The factors associated with NC in this study may serve as a model for identifying parents who are at a high risk of NC and as a foundation for interventions designed to improve compliance.

The Beck Airway Air Flow Monitor as an aid for evaluation of endotracheal tube placement in neonatal patients

We evaluated the Beck Airway Air Flow Monitor (BAAM), through which airflow makes a whistling sound, for its safety and efficacy in confirming that an endotracheal tube is in the trachea. We studied 46 neonates ranging in weight from 0.6 to 3.7 kg. We found that the BAAM consistently produced the desired whistling sound signaling intratracheal placement of the tube in all infants weighing more than 1.5 kg. No adverse effects or complications were noted.

Loss of the CD5+ and CD45RAhi B cell subsets in alcoholics

Chronic alcoholics are frequently immunodeficient, have polyclonal hypergammaglobulinaemia, and often have autoantibodies. Recent work in other diseases has shown that functional distinctions of possible relevance to autoimmunity and immunodeficiency can be found among the B cell subsets defined by differential expression of the surface markers CD5 and CD45RA. Therefore, we have evaluated the CD5, CD45RA B cell subsets of both chronic alcoholics without evidence of active liver disease (AWLD), and alcoholics admitted for acute alcoholic liver disease (ALD). Mean B cell numbers were normal in AWLD, but significantly reduced in ALD. Analysis of B cells by three-colour flow cytometry in 20 patients and 29 controls revealed a sharp decrease in the percentage of alcoholics' B cells which were CD5+, 37.6% versus 16.3%, P < 0.000 01; absolute CD5+ B cell numbers were similarly reduced (58.9 cells/microliters versus 20.9; P = 0.0012). In addition to the loss of CD5+ B cells, there was a reduction in the percentage of B cells which are CD5- CD45RAhi, leaving many patients with a B cell profile which was predominantly CD19+ CD5- CD45RAlo. This subset appears phenotypically similar to the IgM-producing CD5- CD45RAlo subset described by others, and may be enriched for autoantibody-producing cells. One outlier patient was an ALD with 61% of B cells which were CD5+, which also is a profile consistent with increased autoantibody production.

Effect of chronic erythropoietin administration on plasma iron in newborn lambs

Erythropoietin, the primary stimulator of erythropoiesis, represents an important potential therapy for the anemia of prematurity. Enhancement of the therapeutic benefit of recombinant human erythropoietin (rhEp) in very-low-birth-weight infants will require a better understanding of rhEp's pharmacodynamic effects including its interaction with iron in stimulating erythropoiesis. The purpose of this study was to determine the effects of chronic rhEp administration on plasma iron levels and hematopoiesis using a twin lamb model. Nine pairs of twin lambs in which one twin was randomized to receive rhEp, and the other saline, were studied during a 1-week baseline and a subsequent 4- to 5-week treatment period. The effects of therapy on plasma iron levels and erythropoiesis were measured by integrating the areas under the concentration-time curves (AUC) of the study variables. During the rhEp treatment period, significantly greater negative daily AUCs were observed in the rhEp-treated lambs for plasma iron concentration (p = 0.0008), while significantly greater positive daily AUCs were observed for hemoglobin concentration (p = 0.04) and reticulocyte count (p = 0.02). In the rhEp-treated group, pretreatment iron concentrations were directly associated with the magnitude of the iron response during treatment such that the greater the pretreatment iron, the greater the daily AUC below the plasma iron concentration-time plot (r = -0.66, p = 0.05). For the placebo-treated group, this association tended toward, but did not achieve, statistical significance (r = -0.52, p = n.s.). These observations suggest that treatment of rapidly growing newborn lambs with rhEp results in increased iron utilization due to increased erythropoiesis and depends on iron status at the initiation of rhEp treatment. Use of the term neonatal lamb model offers advantages over studies in human infants for more detailed or invasive examinations of the interaction of iron and rhEp treatment.

The Institute of Medicine report on emergency medical services for children: thoughts for emergency medical technicians, paramedics, and emergency physicians

The emergency medical technician, the paramedic, and the emergency physician, as well as emergency physicians who have additional expertise in emergency medical service (EMS) prehospital care or pediatric emergency medicine (through experience or formal fellowship training), will all find the Institute of Medicine's report, Emergency Medical Services for Children (EMS-C), to be an invaluable background resource as well as a guide for EMS system and EMS-C-related planning. With both breadth and depth, it reviews many of the issues in EMS-C today from many perspectives and provides practical information to enable these care givers to understand better the "big picture" of EMS-C as well as to assist them in continuing to make a difference in the day-to-day emergency care for children. It is well referenced, engenders respect for all members of the team within the broad continuum of EMS-C, and provides encouragement to them to work together to identify and address issues and solve problems to improve the quality of care for our nation's children.

Modulation of T-cell adhesion markers, and the CD45R and CD57 antigens in human alcoholics

Direct and indirect evidence indicates that T cells are altered in alcoholics. The most commonly reported changes under direct examination have been consistent with an increased level of activation as reflected by shifts in the ratio of common leukocyte antigen isoforms expressed at the cell surface, by increases in the expression of class II antigen, or by alterations in the expression of various adhesion molecules. Functional evidence for T-cell abnormality includes loss of delayed hypersensitivity and a number of findings attributed to dysregulation of B cells by alcoholic T cells; these include the widely reported distrubances of immunoglobulin production in vivo and a range of abnormal responses when T and B cells are combined in vitro. Detailed flow cytometric examination of T cells from alcoholics with or without active liver disease reveals a significant loss of L-selectin CD8+ T cells, but not usually of CD4+ T cells. There is an inverse increase in the expression of CD11b on the CD8+ cells that have decreased L-selectin+ percentages. Both CD8+ and CD4+ T cells in alcoholics display a significant loss of the CD45RA isoform and a gain of cells exhibiting the CD45RO isoform. Other surface alterations include increased expression of CD57, a marker most commonly associated on T cells with conditions of chronic increased antigenic exposure. It is argued that these and other T-cell alterations in alcoholics are cytokine-driven in part and result in T-cell differentiation states that are functionally inappropriate.(ABSTRACT TRUNCATED AT 250 WORDS)

Use of a Beck Airway Airflow Monitor and controllable-tip endotracheal tube in two cases of nonlaryngoscopic oral intubation

Alternative techniques and equipment for intubation may be particularly useful in settings such as air-medical transport, prehospital on-scene care, mass casualty incidents, or incidents in which there may be a lack of medications or equipment. Once traditional techniques of endotracheal intubation and tube verification have been mastered, emergency medicine residents and other intubators should be encouraged to learn alternative techniques, such as these, that may be of use in some special situations, even within the ED. Neither of these two techniques of BAAM-assisted blind oral intubation can be considered essential, nor should it be contended that these techniques supplant learning of more conventional methods of endotracheal intubation and tube placement verification. However, particularly in the setting of residency training, multiple methods of endotracheal intubation should be taught in order to allow the clinician alternative methods if unable to intubate by traditional means in a particular setting. Use of a BAAM to assist in blind oral intubation of a spontaneously breathing patient may allow for oral intubation of awake patients without the additional use of paralytic medications. Use of the BAAM with a digital technique during external cardiac massage may facilitate intubation by the digital technique and help to verify endotracheal tube position. These two additional uses for the BAAM should be noted and these two additional methods of airway control be recognized as backup methodologies in the armamentarium for situations in which they may be needed.

Adenosine in the termination of albuterol-induced supraventricular tachycardia

Five percent of children in the United States have asthma. Status asthmaticus is one of the most common conditions for which children seek care in a pediatric emergency department. beta 2-Agonists such as albuterol are the mainstay of emergency therapy for such children. We present a case of a 4-year-old boy who experienced supraventricular tachycardia (SVT) following albuterol therapy. This is believed to be the first report of adenosine being successfully used to treat a child with albuterol-induced SVT. We also briefly review the recognition and management of SVT in children and the pharmacokinetics of and indications for adenosine.

Fine T-cell subsets in alcoholics as determined by the expression of L-selectin, leukocyte common antigen, and beta-integrin

Alcoholics admitted to the hospital solely for detoxication have been studied by flow cytometry to evaluate changes in the surface markers of peripheral blood leukocytes. As we have shown previously, such patients have an elevated percentage of CD8hi lymphocytes that are HLA DR+; we now demonstrate that they also have striking alterations in the quantitative relationships of the fine T-cell subsets. Both CD4+ and CD8hi lymphocytes have a sharply reduced percentage of the L-selectin+ CD45RA+ subset, increased percentages of the CD45RA- subsets, and several other fine subset alterations. The fine subset profile suggests, according to current correlations of phenotype and function, that both CD4+ suppressor inducer and CD4-dependent CD8+ suppressor effector cells are reduced, whereas other subsets, including CD8+ CTL or their precursors, are increased in relative percentages. Some of the phenotypic changes are reversible over the several days following withdrawal. In other results, the percentage of CD8hi lymphocytes epxressing CD11b (beta-integrin) is shown to be reciprocal with the percentage expressing L-selectin both in normals and alcoholics. However, the regression function of CD11b vs. L-selectin on CD8hi cells is different for the alcoholics than for the normals, indicating an abnormality in the regulation of the expression of these two adhesion markers. Taken together, this abnormality of adhesion molecules and the fine subset alterations previously described indicate widespread changes in the peripheral lymphocytes of currently drinking alcoholics. These changes suggest functional deficiencies that may include alterations of lymphocyte traffic and other adhesion-dependent functions, and a shift in the balance of regulatory interactions.

Vulnerability of cerebellar granule cells to alcohol-induced cell death diminishes with time in culture

This study examined the effects of alcohol exposure on the viability of cerebellar granule cells in culture. Continuous alcohol exposure, starting 1 day after the cultures were established, significantly reduced granule cell numbers, even with a single day of exposure to an alcohol concentration as low as 100 mg/dl. The depletion of cerebellar granule cells by alcohol was concentration-dependent (greater loss of cells at higher alcohol concentrations) and duration-dependent (greater loss of cells at longer exposure durations). The loss of granule cells also depended on the number of days the granule cells were in culture before alcohol exposure. Alcohol was significantly more effective in reducing the cell numbers of newly established granule cell cultures (1 day in vitro) compared with older cultures (4 or 7 days in vitro). Cell cycle analysis established that the cerebellar granule cells did not proliferate in culture, indicating that alcohol exposure did not reduce cell numbers by interfering with cell proliferation in this system. Instead, alcohol-induced killing of the granule cells was the most likely mechanism to account for the depletion of granule cells in vitro. Granule cell cultures are a useful in vitro model system to study the cellular and molecular aspects of neuronal cell depletion associated with fetal alcohol exposure. The potential role of the N-methyl-D-aspartate receptor in this alcohol-induced neuronal cell death is discussed.

The BAAM and endotrol endotracheal tube for blind oral intubation. Beck Airway Air Flow Monitor

Blind oral intubation in a spontaneously breathing patient can be facilitated with a combination of two devices used mainly for nasotracheal intubation, the BAAM (Beck Airway Air Flow Monitor, Great Plains Ballistics, Lubbock, TX) and the Endotrol endotracheal tube (Mallinckrodt Critical Care, Inc., St. Louis, MO). We describe a case in which intubation of a spontaneously breathing intensive care unit patient was unsuccessful by traditional methods. In the successful approach we describe, the tube was passed through the oral cavity and pharynx in a blind fashion, using the BAAM's whistling sound for guidance and the plastic ring of the Endotrol tube to help positioning. This equipment combination may be useful in certain difficult intubation situations.

Programs and pregnancy: a survey of policies

If a woman becomes pregnant while on flight status, a potential conflict exists between the needs and desires of the program and those of the flight crew member. Association of Air Medical Services (AAMS) member programs were surveyed to determine the extent of pregnancy policy standards within the air medical profession. A survey was mailed to 150 AAMS program directors in the fall of 1988. The survey was followed with a second mailing and a telephone follow-up for clarification. Replies were received from 110 program directors. Fifty-five percent of those responding noted they had a policy on flight crew member (FCM) pregnancy. Thirty percent noted a date prior to term that the pregnant FCM (PFCM) would be removed from flight status. Seventy percent of the programs noted that they had not previously had a PFCM. Over half of the programs allowed PFCMs to fly until the third trimester, with just under a quarter allowing flights until 38 weeks or greater. There are few articles specifically referring to air medical FCM pregnancy, and policies regarding FCM pregnancy differ widely among the AAMS member programs.

Biologic fate of cryopreserved human saphenous allografts: case report and hypothesis

A femoroperoneal bypass using a cryopreserved human saphenous allograft was performed on a patient who presented with critical ischemia of the left lower extremity. The patient died of myocardial infarction 48 hours later and the graft was examined histologically. There was karryorhexis and focal neutrophilic infiltrate in the media underlying a layer of fibrin on the intimal surface. Immunoperoxidase studies showed nonspecific luminal deposition of immunoglobulins and fibrinogen. The histologic changes that occur in cryopreserved venous allografts are similar in experimental and human material and may be the result of anoxia of the vessel wall rather than immunologic mechanisms.

Is the anteroposterior cervical spine radiograph necessary in initial trauma screening?

The usefulness of the anteroposterior (AP) radiograph of the cervical spine in contributing to the diagnosis of cervical spine injuries in the acute trauma patient was examined in a retrospective study. All cases of cervical spine fracture or dislocation seen at a level I trauma center over a 3-year period and at a rehabilitation center over a 10-year period were reviewed. The lateral radiograph, open-mouth odontoid radiograph, and AP radiograph of each case were sequentially examined by a neuroradiologist (blinded to the original diagnosis) to determine the contribution of each view in making a diagnosis of cervical spine injury. Results of these reviews showed that there were no cases of cervical spine injury evident on the AP view without an obvious corresponding abnormality on the lateral or open-mouth view. It was concluded that the AP view could be dropped from the initial screening radiographic study of the cervical spine in the trauma patient. Only an adequate lateral view and open-mouth odontoid view would then be necessary to initially evaluate the cervical spine in the trauma patient, and decisions to obtain further studies could be based safely on only the lateral and open-mouth views.

Activated CD-8 cells and HLA DR expression in alcoholics without overt liver disease

Lymphocytes from alcoholics without liver disease were immunophenotyped by flow cytometry immediately after admission for detoxication and again after 4 to 10 days of abstinence. We found a small but significant elevation of T lymphocytes at admission compared to controls and decreases in the numbers of B cells and natural killer cells in many patients. A significant elevation of activated T cells was confirmed. The ratio of activated T cells to activated non-T cells was also substantially increased, but declined slightly during early withdrawal. The increase in activated T cells was due mostly to increased numbers of activated CD8hi cells. These activation changes did not revert toward normal as quickly as the other changes and may represent an indication of immune damage at a preclinical stage. An additional finding of interest was a substantial decrease in the expression of HLA DR on CD4+ and non-T cells. The significance of this decrease is not known, but we speculate that it may result in a decline in the efficiency of antigen presentation.

Ethanol-induced growth inhibition of erythroleukemia stem cells. Cell cycle effects

Friend erythroleukemia stem cells are strongly growth inhibited by 60 mM ethanol. The expression of this inhibition requires several days to develop fully, and is not relieved by washing into new ethanol-containing medium even in the presence of excess folic acid. Removal of the fully inhibited cells from ethanol results in rapid growth recovery, with the onset of recovery occurring within a few hours. Cell cycle analysis reveals a G1 delay which is evident within a few hours after initial ethanol exposure. Bivariate RNA-DNA analysis indicates that this G1 delay results from restriction in late G1. It is unclear at present whether this delay can account for all the observed growth inhibition.

Ethanol causes accelerated G1 arrest in differentiating HL-60 cells

The effects of clinically relevant ethanol concentrations on myeloid differentiation in the HL-60 cell promyelocytic leukemia line have been studied. The exposure of noninduced stem cells to 60 mM ethanol results in an increase in G1 cells, but there is no increase in superoxide production or expression of the Mo1 antigen. When HL-60 cells are induced to differentiate along the myeloid line with dimethylsulfoxide (DMSO) or retinoic acid (RA), there is a shift to smaller cell size, an increase in G1 cells and acquisition of the ability to produce superoxide as reported previously by several authors. When ethanol is present during differentiation, there are further increases in G1 cells, and increases in the percentage of cells which produce superoxide and express Mo1, and decreases in mean cell size and total growth during the incubation period. Regrowth experiments after periods of differentiation indicate that the increased G1 arrest seen in the presence of ethanol represents terminal commitment if inducer is present, but in the absence of inducer the increased G1 percentage is readily reversible. Examination of RNA content by flow cytometry reveals a decrease in both the peak and mean G1 RNA content during DMSO or RA induced differentiation. These decreases are accentuated by the presence of ethanol, resulting in a higher G1A/G1B ratio than in nonexposed cells. These findings indicate that ethanol enhances G1 growth arrest in HL-60 cells exposed to myeloid inducers. Partial differentiation occurs during this process, resulting in terminally arrested cells, some of which have undergone fewer postinduction cell divisions than normal and may not be fully competent.

Pneumocystis carinii. Taxonomy as viewed by electron microscopy

Pneumocystis carinii is an opportunistic unicellular organism that can cause serious pulmonary infection in immunosuppressed patients. The taxonomy and classification of P. carinii has not yet been settled. The authors present transmission and scanning electron microscopic (TEM and SEM) observations of tissue from two patients with pulmonary Pneumocystis infections. The infectious organisms display marked variability in shape and size. They appear to divide by binary fission and lack motility organelles, Golgi apparatus, phagosomes, and lysosomes. The mitochondria and endoplasmic reticulum were poorly developed. The nucleus was rather ill defined, and there appeared to be asynchrony in the development of nuclear membranes and cytoplasm. The authors contend that there are firm ultrastructural evidences against the claim for a protozoan nature of Pneumocystis and in favor of its being a fungus, albeit of a primitive form, in which the mycelium is reduced to a unicellular state but the ability to sporulate is preserved.

Recognition of a site of a Kentucky bluegrass pollen allergen by antibodies in the sera of allergic and non-atopic humans and a murine monoclonal antibody

Allergen 27 was isolated from the aqueous extract of Kentucky Bluegrass pollen (KBG-R) with a reversed immunosorbent prepared by coupling murine monoclonal antibody, Mab 27, to Sepharose 4B. Sera of patients allergic to KBG pollen, as well as serum of nonatopic individuals possessing anti-KBG antibodies, inhibited the binding of Mab 27 to either Ag 27 or KBG-R to the extent of 20 to 35% in ELISA. In contrast, sera devoid of antibodies to KBG-R had no inhibitory capacity. In a radioallergosorbent test, it was demonstrated that Mab 27 could inhibit the binding of human IgE antibodies to Ag 27 to the extent of 52%. From these results, it is concluded that Ag 27 contains a determinant recognized by both human IgE and blocking antibodies and a murine Mab.

Recognition of a site of a Kentucky bluegrass pollen allergen by antibodies in the sera of allergic and non-atopic humans and a murine monoclonal antibody

Allergen 27 was isolated from the aqueous extract of Kentucky Bluegrass pollen (KBG-R) with a reversed immunosorbent prepared by coupling murine monoclonal antibody, Mab 27, to Sepharose 4B. Sera of patients allergic to KBG pollen, as well as serum of nonatopic individuals possessing anti-KBG antibodies, inhibited the binding of Mab 27 to either Ag 27 or KBG-R to the extent of 20 to 35% in ELISA. In contrast, sera devoid of antibodies to KBG-R had no inhibitory capacity. In a radioallergosorbent test, it was demonstrated that Mab 27 could inhibit the binding of human IgE antibodies to Ag 27 to the extent of 52%. From these results, it is concluded that Ag 27 contains a determinant recognized by both human IgE and blocking antibodies and a murine Mab.