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Biomedical subjects

L Simon

Publications and source records attributed to L Simon.

At least 55 records · Page 3Linked to original sources
PubMed1998

Terror management and aggression: evidence that mortality salience motivates aggression against worldview-threatening others.

The hypothesis that mortality salience (MS) motivates aggression against worldview-threatening others was tested in 4 studies. In Study 1, the experimenters induced participants to write about either their own death or a control topic, presented them with a target who either disparaged their political views or did not, and gave them the opportunity to choose the amount of hot sauce the target would have to consume. As predicted, MS participants allocated a particularly large amount of hot sauce to the worldview-threatening target. In Studies 2 and 3, the authors found that following MS induction, the opportunity to express a negative attitude toward the critical target eliminated aggression and the opportunity to aggress against the target eliminated derogation. This suggests that derogation and aggression are two alternative modes of responding to MS that serve the same psychological function. Finally, Study 4 showed that MS did not encourage aggression against a person who allocated unpleasant juice to the participant, supporting the specificity of MS-induced aggression to worldview-threatening others.

Adult↗
PubMed1998

Acute pancreatitis after orthotopic liver transplantation in children: incidence, contributing factors, and outcome.

BACKGROUND: Acute pancreatitis after orthotopic liver transplantation is a well-known complication in adults that has never been described in children. In adults, end-stage liver disease related to hepatitis B, intraoperative pancreatic injury caused by extensive peripancreatic dissection, the type of biliary anastomosis performed, and numerous drugs, have all been described as predisposing factors in acute pancreatitis after liver transplantation. The current retrospective review was undertaken to identify the incidence, the contributing factors, and the outcome of acute pancreatitis after liver transplantation in children. METHODS: During a 10-year period, 375 children underwent 434 liver transplantations in the authors' institution. In seven patients (1.9%), clinical acute pancreatitis developed after orthotopic liver transplantation. Indication for initial liver transplantation was biliary atresia (n = 3), acute liver failure (n = 3), and type 1 Crigler-Najjar syndrome. In all seven patients, liver graft function was initially adequate. The diagnosis of acute pancreatitis was based on clinical, biochemical, ultrasonographic, and surgical signs. RESULTS: In six patients, acute pancreatitis appeared within the first week after transplantation. The diagnosis was confirmed by abdominal laparotomy in five children. In the current series, emergency liver transplantation (p < 0.001), retransplantations (p < 0.001), and infectious peritonitis (p < 0.001) were contributing factors. Despite supportive measures, three patients died (43%) because of multiple organ dysfunction syndrome. CONCLUSIONS: Acute pancreatitis is an uncommon but life-threatening complication after liver transplantation in children. Early diagnosis and aggressive treatment of infectious complications are major elements in the management of acute pancreatitis after liver transplantation.

Acute Disease↗
PubMed1998

Terror management and meaning: evidence that the opportunity to defend the worldview in response to mortality salience increases the meaningfulness of life in the mildly depressed.

Previous terror management research has demonstrated that mildly depressed participants show a greater increase in worldview defense in response to reminders of their mortality than do nondepressed participants. Because the cultural worldview is posited to provide a meaningful conception of life, we hypothesized that mildly depressed participants who defend their worldview in response to mortality salience (MS) would increase their perception that the world is meaningful. A preliminary study first examined the Kunzendorf No Meaning Scale as a measure to assess perceptions of meaning. In the primary study, mildly depressed and nondepressed participants contemplated their own mortality or a neutral topic, evaluated two targets in a manner that either allowed them to defend their worldview or that did not, and then completed the Kunzendorf No Meaning Scale. As predicted, mildly depressed participants who had the opportunity to defend their worldview in response to mortality salience reported greater meaning in life than did mildly depressed participants who did not have the opportunity to defend their worldview, or mildly depressed participants not exposed to mortality salience. Implications for understanding and treating depression are briefly discussed.

Adult↗
PubMed1998

Intestinal uptake of particulate material by dexamethasone-treated rats: use of a novel technique to avoid intestinal mucosal contamination.

The aim of this study was to investigate the effect of immune suppression on the uptake of particles across the wall of the intestine and the dissemination of the particles to systemic organs. Normal and dexamethasone-immunosuppressed rats were dosed orally with 0.5 mL distilled water or fluorescent polystyrene latex particle suspension containing 2.33 x 10(9) 2-microm diameter particles. One hour after particle dosing, the animals were killed by CO2 asphyxiation. The intestinal tissues and systemic organs were sampled for particle quantitation. To avoid contamination by particles adherent to intestinal mucosa the epithelium of intestinal tissue samples was removed before quantification. The number of fluorescent particles in tissues was determined by fluorescence microscopy of digests of selected samples. The uptake of particulate material across the intestinal wall was significantly (P < 0.05) increased in rats treated with dexamethasone but the number of particles transferred to systemic organs did not differ from values found for control animals. The results suggest that although dexamethasone increased intestinal permeability the apparatus or mechanisms involved in particle transport to distal sites were not affected during immune suppression.

Administration, Oral↗
PubMed1998

Transepithelial transport of large particles in rat: a new model for the quantitative study of particle uptake.

The transport of large particles across the intestinal mucosa and the mechanisms of transfer of the particles into the body are still little understood. Fluorescent polystyrene latex particles (2 microm diam.) were administered orally to young male Sprague-Dawley rats in doses of 2.33 x 10(3), 2.33 x 10(6) and 2.33 x 10(9) particles. After 60 min, Peyer's patches and Peyer's patch-free tissues were collected from the small intestine and colon. A novel technique was used to exclude non-translocated particles adherent to the mucosal surface; the intestinal epithelium was stripped from the intestine by immersion in Hanks' balanced salt solution containing 1.5 mM EDTA. Particles in solubilized samples of intact and epithelium-stripped Peyer's patches and Peyer's patch-free intestinal tissue and colon were quantified by fluorescence microscopy. The location of particles within the intact and epithelium-stripped gut samples was revealed by confocal microscopy. Particles were shown to have been taken up along the entire length of the small and large intestines via both Peyer's patches and the normal intestinal epithelium. The number of particles detected in the distal region was greater than in the proximal part of the small intestine, although the difference was not statistically significant. This study has revealed that large numbers of non-translocated particles adhered to the mucosal surface resulting in a high background count. The assay system was considerably improved by the epithelium-stripping technique. The process of transepithelial uptake is a potentially important route of uptake of toxic, immunologically active and radioactive substances. These particles are much larger than the conventionally accepted upper limit for absorbed materials.

Administration, Oral↗
PubMed1998

[Multiple osteonecrosis in a patient with chronic alcoholism].

The osteonecrosis is usually due to various precipitating circumstances or predisposing factors that quite often appear mixed, although it can also appear with no evident cause. In this report, we provide a case of multiple osteonecrosis caused by chronic alcoholism, we review the literature and go over the general characteristics of the aseptic necrosis.

Aged↗
PubMed1997

Preclinical studies for cell transplantation: isolation of primate fetal hepatocytes, their cryopreservation, and efficient retroviral transduction.

Fetal hepatocytes are an attractive target for in utero cellular transplantation. Their use could provide a very efficient way for implanting normal or transduced cells into the livers of affected fetuses. Marking cells with recombinant retroviruses is a powerful tool for evaluating the chimerism of grafted animals. The technique relies on the ex vivo transduction efficiency of the engrafted cells. We have isolated fetal primary hepatocytes from nonhuman primates. The cells were cultured and transduced with a retroviral vector carrying the Escherichia coli beta-galactosidase gene. Optimal gene transfer efficiency was obtained 48-60 hr after plating and was as high as 90%. Cryopreservation had little effect on cell viability and infectivity: The viability of thawed hepatocytes remained high (75-85%) and the infection efficiency was identical to that of freshly isolated cells. Efficient ex vivo retroviral gene transfer into fetal hepatocytes provides an appropriate system for testing allogenic grafting and for modifying immunogenicity of engrafted cells. These results open up new perspectives for cell transplantation through cell banking.

Animals↗
PubMed1997

Anatomical basis of a common embryological origin for epispadias and bladder or cloacal exstrophies.

Epispadias, bladder exstrophy and its variants are in the first place usually considered as urological anomalies. Embryological theses and therapeutic approaches are mainly based upon this aspect. We challenge this point of view, in order to bring out a new axis of research about this still misknown pathologic field. A review of 16 cases of bladder exstrophy, 6 epispadias cases, and one cloacal exstrophy case, which had never been described before, revealed that the almost constant bony defect of the pelvic ring was linked with the severity of the visceral features, and with the continence status in epispadias cases. The commonly admitted theories about exstrophy development are based on a primary defect of the cloacal membrane. We suggest that the first anomaly could lie in a lack of rotation in the pelvic ring primordia.

Bladder Exstrophy↗
PubMed1997

[Evaluation of hemostasis before obstetrical epidural anesthesia: a survey in 435 French obstetric departments].

OBJECTIVES: To specify by which means French anaesthesiologists evaluate the haemostasis profile of pregnant women before epidural analgesia. STUDY DESIGN: Nationwide retrospective survey. MATERIAL: Questionnaire sent of 847 French obstetrical units. METHODS: Comparison of categorical qualitative parameters using a chi 2 test. RESULTS: Answers from 435 centres, including 1,834 anaesthesiologists, performing 227 x 10(3) epidurals for 411 x 10(3) deliveries/year were obtained. A preanaesthetic clinical assessment was performed systematically in two out of three units, and blood samples for PT, aPTT and platelet count were taken in more than 90% of the centres. These laboratory examinations were often made during the 9th month of pregnancy (74%). For more than one-third of the anaesthesiologists, biological data are not essential before epidural puncture. In addition, the lower limits considered as being safe before epidural puncture were highly variable between the teams. CONCLUSIONS: Coagulation laboratory tests are almost always ordered before epidural obstetrical analgesia in France. The rationale to perform them is not always related to pregnancy induced haemostatic changes. Therefore, this problem should be clarified by a consensus conference for both practical and economical reasons.

Adult↗
PubMed1997

[Agranulocytosis after application of silver sulfadiazine in a 2-month old infant].

BACKGROUND: A granulocytosis associated with the use of silver sulfadiazine has been described in burn patients. This agranulocytosis may be due to either an allergic reaction or a bone marrow toxicity by silver sulfadiazine. CASE REPORT: A 1-month old baby was hospitalized in pediatric intensive care unit after a stage one repair of a tracheoesophegeal fistula. Gastroesophageal reflux and tracheomalacia appeared in the post operative period. When she was 2-months old, she developed a perineal erythema. A topical therapy was begun, with daily applications of silver sulfadiazine and ketoconazole. Five days later, agranulocytosis (granulocytes = 0.21 x 10(9).L-1) occurred. Silver sulfadiazine therapy was immediately stopped. Granulocyte count returned to normal over a few days. No other etiology than silver sulfadiazine could be found to explain agranulocytosis. The small surface of administration, the chronology of the events and the rapid correction of the disorders after silver sulfadiazine interruption argued for an immuno-allergic reaction to this drug. Medical problems were easily controlled and the patient recovered well. CONCLUSION: This event occurred when sulfadiazine was applied in a small cutaneous area in a young baby. This may be an argument for an allergic reaction; alternatively, it could be explained by an increased cutaneous absorption of a cytotoxic drug in younger people.

Agranulocytosis↗
PubMed1997

Effect of solid and liquid diet on uptake of large particulates across intestinal epithelium in rats.

The effect of diet composition on the uptake of particulates across the gastrointestinal epithelium has been examined in fasted male weanling Sprague-Dawley rats by estimating the systemic uptake of orally administered 2-microns latex polystyrene microspheres. Using a tissue solubilization assay, particle transfer in animals maintained on a fluid diet was determined. A larger number of particles was transferred from the gut lumen to the internal organs, including the mesenteric lymph node, spleen, bone marrow, liver, kidney, and heart of animals fed solid pelleted diet than those maintained on a fluid-diet 4 hr after oral administration of particles. The increase in particle number in rats fed the solid diet was only statistically significant (P < 0.05) for brain tissue in the analysis for trend. However, the number of particles retained in the proximal region of the gut at the end of this period was greater in animals fed the fluid diet. This work demonstrates that diet composition is important in gastrointestinal transepithelial translocation of microspheres.

Adolescent↗
PubMed1997

Terror management theory and self-esteem: evidence that increased self-esteem reduces mortality salience effects.

On the basis of the terror management theory proposition that self-esteem provides protection against concerns about mortality, it was hypothesized that self-esteem would reduce the worldview defense produced by mortality salience (MS). The results of Experiments 1 and 2 confirmed this hypothesis by showing that individuals with high self-esteem (manipulated in Experiment 1; dispositional in Experiment 2) did not respond to MS with increased worldview defense, whereas individuals with moderate self-esteem did. The results of Experiment 3 suggested that the effects of the first 2 experiments may have occurred because high self-esteem facilitates the suppression of death constructs following MS.

Analysis of Variance↗
PubMed1997

Terror management and cognitive-experiential self-theory: evidence that terror management occurs in the experiential system.

The authors hypothesized, on the basis of terror management theory and cognitive-experiential self-theory, that participants in an experiential mode of thinking would respond to mortality salience with increased worldview defense and increased accessibility of death-related thoughts, whereas participants in a rational mode would not. Results from 3 studies provided convergent evidence that when participants were in an experiential mode, mortality salience produced the typical worldview defense effect, but when participants were in a rational mode it did not. Study 4 revealed that mortality salience also led to a delayed increase in the accessibility of death-related thoughts only when participants were in an experiential mode. These results supported the notion that worldwide defense is intensified only if individuals are in an experiential mode when considering their mortality. Discussion focuses on implications for understanding terror management processes.

Adaptation, Psychological↗
PubMed1997

Suppression, accessibility of death-related thoughts, and cultural worldview defense: exploring the psychodynamics of terror management.

Previous research has shown that after a mortality-salience (MS) treatment, death thought accessibility and worldview defense are initially low and then increase after a delay, suggesting that a person's initial response to conscious thoughts of mortality is to actively suppress death thoughts. If so, then high cognitive load, by disrupting suppression efforts, should lead to immediate increases in death thought accessibility and cultural worldview defense. Studies 1 and 2 supported this reasoning. Specifically, Study 1 replicated the delayed increase in death accessibility after MS among low cognitive load participants but showed a reversed pattern among participants under high cognitive load. Study 2 showed that, unlike low cognitive load participants, high cognitive load participants exhibited immediate increase in pro-American bias after MS. Study 3 demonstrated that worldview defense in response to MS reduces the delayed increase in death accessibility. Implications of these findings for understanding both terror management processes and psychological defense in general are discussed.

Affect↗
PubMed1997

Pre-anaesthetic assessment of coagulation abnormalities in obstetric patients: usefulness, timing and clinical implications.

The usefulness and optimal timing of laboratory coagulation tests before obstetric extradural analgesia are controversial. Moreover, the significance of mild coagulation abnormalities during pregnancy remains unclear. We have assessed the reliability of coagulation tests performed several weeks before delivery as predictors of coagulation abnormalities during labour. Platelet count, plasma fibrinogen concentration, prothrombin time (PT) and activated partial thromboplastin time (aPTT) were sampled in 797 women during the ninth month of pregnancy and checked during labour. Platelet count was less than 100 x 10(9) litre-1 for 11 women during labour. Only three had been detected by the first sample. Platelet count less than 100 x 10(9) litre-1 or fibrinogen concentration less than 2.9 g litre-1 during labour were associated with an increase in the incidence of postpartum haemorrhage (odds ratio = 19.7). We conclude that a platelet count several weeks before delivery was not reliable in predicting thrombocytopenia during labour and that women with mild coagulation abnormalities in early labour may need special attention regarding the risk of postpartum haemorrhage.

Adult↗
PubMed1997

Progression into the first meiotic division is sensitive to histone H2A-H2B dimer concentration in Saccharomyces cerevisiae.

The yeast Saccharomyces cerevisiae contains two genes for histone H2A and two for histone H2B located in two divergently transcribed gene pairs: HTA1-HTB1 and HTA2-HTB2. Diploid strains lacking HTA1-HTB1 (hta1-htb1 delta/hta1-htb1 delta, HTA2-HTB2/HTA2-HTB2) grow vegetatively, but will not sporulate. This sporulation phenotype results from a partial depletion of H2A-H2B dimers. Since the expression patterns of HTA1-HTB1 and HTA2-HTB2 are similar in mitosis and meiosis, the sporulation pathway is therefore more sensitive than the mitotic cycle to depletion of H2A-H2B dimers. After completing premeiotic DNA replication, commitment to meiotic recombination, and chiasma resolution, the hta1-htb1 delta/hta1-htb1 delta, HTA2-HTB2/HTA2-HTB2 mutant arrests before the first meiotic division. The arrest is not due to any obvious disruptions in spindle pole bodies or microtubules. The meiotic block is not bypassed in backgrounds homozygous for spo13, rad50 delta, or rad9 delta mutations, but is bypassed in the presence of hydroxyurea, a drug known to inhibit DNA chain elongation. We hypothesize that the deposition of H2A-H2B dimers in the mutant is unable to keep pace with the replication fork, thereby leading to a disruption in chromosome structure that interferes with the meiotic divisions.

Histones↗