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Biomedical subjects

L Carpentier

Publications and source records attributed to L Carpentier.

14 recordsLinked to original sources
PubMed2006

Molecular mobility in glass forming fananserine: a dielectric, NMR, and TMDSC investigation.

PURPOSE: This study was conducted to characterize the molecular mobility of supercooled fananserine and derive from this analysis the non-Arrhenius and nonexponential properties of the primary alpha-relaxation. METHODS: The use of three investigation techniques of the molecular mobility, namely, dielectric relaxation, modulated differential scanning calorimetry, and proton nuclear magnetic resonance, allowed us to describe the dynamic properties of supercooled fananserine on a wide range of frequencies and temperatures, ranging from the melting temperature T(m) = 372 K down to the glass transition temperature T(g) = 292 K. RESULTS: We emphasized the capacity of these three techniques to give a coherent set of information. We used the coupling-model theory to interpret the dielectric results. It allowed us to identify two relaxation processes (alpha and beta), corresponding to different molecular motions. The temperature evolution of the alpha-relaxation indicates that fananserine is a fragile glass former, as reflected by the steepness index value, m = 77. The temperature T(o) where the relaxation times diverge was also determined. CONCLUSIONS: The description of the dielectric relaxation data in terms of the Kohlrausch-Williams-Watt relaxation function has shown the existence of an additional low-amplitude relaxation process assigned to the so-called Johari-Goldstein process. Mainly concerned by the primary alpha-process directly involved in the glass formation, we derived from this analysis the characteristic features of this process and showed that supercooled fananserine is characterized by a strongly non-Arrhenius and nonexponential behavior.

Air Pressure↗
PubMed2006

Dynamics of the amorphous and crystalline alpha-, gamma-phases of indomethacin.

Crystallization processes in indomethacin can be observed below Tg leading to different forms depending on the thermal treatment: a rapid and deep quench below Tg leads to the metastable alpha-phase and a slow cooling close to Tg gives rise to the stable gamma-phase. To understand this atypical behavior, we have studied the molecular mobility of the amorphous and crystalline forms of indomethacin by dielectric relaxation and 1H NMR spectroscopy. Two relaxations were detected in the glassy state obtained from the deeply quenched liquid. One, also present in the gamma-phase, was attributed to local rotations. The other one, of very low amplitude, was attributed to the Johari-Goldstein relaxation. The results allowed to discuss the relationship between these two relaxation processes and the crystallization properties of amorphous indomethacin.

Crystallization↗
PubMed2005

Nuclear magnetic resonance and dielectric investigations of molecular motions in a glassy crystal: the mixed compound (CN-adm)0.75(Cl-adm)0.25.

The dynamic properties of plastic crystalline mixed adamantane's derivatives namely cyanoadamantane (75%) and chloroadamantane (25%) were investigated by dielectric and nuclear magnetic resonance (NMR) spectroscopy, covering a spectral range of 12 decades in the temperature range 110-420 K. Phase transformations were studied and dynamical parameters of the plastic (I), glassy (Ig), and ordered (III) phases were determined and compared with those of pure compounds. The dynamics of the supercooled plastic phase is characterized by an alpha-process exhibiting an Arrhenius behavior which classified the mixed compound as a strong glass former. In the plastic phase, NMR relaxation times were interpreted by using a Frenkel model, which takes into account structural equilibrium positions. This model explains adequately the experimental results by considering two molecular motions. In both the glassy state and plastic phase the motional parameters agree with those of 1-cyanoadamantane. On the contrary, in the ordered phase, the motional parameters related to the uniaxial rotation of chloroadamantane molecules indicate an accelerated motion.

Journal Article↗
PubMed2004

Relaxation modes in glass forming meta-toluidine.

The dynamics in supercooled meta-toluidine was studied using dielectric relaxation, modulated differential scanning calorimetry, proton spin-lattice relaxation times, and viscosity measurements. The combination of these different techniques has clearly shown a large decoupling of the relaxation modes whose origin is attributed to the formation of clusters via the NH2 bonding. This decoupling starts at a temperature also corresponding to a change of the dynamical behavior from a high temperature Arrhenius evolution to a Vogel-Fulcher-Tamman low temperature evolution.

Journal Article↗
PubMed2003

Comparison of remifentanil and alfentanil during anaesthesia for patients undergoing direct laryngoscopy without intubation.

BACKGROUND: Remifentanil and alfentanil are opioids often used during direct laryngoscopy (DL). This prospective, randomized study compared these agents with respect to haemodynamic and Bispectral Index (BIS) responses, glottic visualization, and rapidity of recovery (spontaneous ventilation, eye opening) in DL without intubation. METHODS: A total of 60 patients undergoing DL were randomized into two groups: remifentanil (R) and alfentanil (A). Anaesthesia was induced with propofol 2.5 mg kg(-1) and the opioid was administered 1 min later (R=2 microg kg(-1) or A=30 microg kg(-1) over 30 s). DL was commenced 1 min after (corresponding to 3 min after the beginning of induction). Glottic visualization, opioid and/or propofol re-injection, spontaneous ventilation recovery, and eye opening were recorded. RESULTS: During DL, mean arterial pressure (MAP) increased by 6% in the R group vs 20% in the A group (P<0.05) when compared with post-induction values without affecting heart rate or BIS. No significant difference was observed between groups with respect to glottic exposure, opioid and/or propofol re-injection, and spontaneous ventilation recovery (mean (SEM) 3.8 (0.6) min, R group vs 3.2 (0.7) min, A group, NS) or eye opening (7.1 (1.1) min, R group vs 7.4 (0.9) min, A group, NS). Thirty minutes after postanaesthesia care unit (PACU) admission, MAP returned to its pre-induction value in the R group (104 (3) vs 109 (3) at baseline, NS), whereas in the A group MAP remained significantly lower at this time point (96 (4) vs 106 (3) at baseline, P<0.05). CONCLUSION: This study showed that only remifentanil prevented MAP increase without adverse effects such as bradycardia during DL, and prevented MAP decrease 30 min after PACU admission.

Adult↗
PubMed2002

[Autoantibodies and anti-factor VIII and Chlamydia pneumoniae infection].

We report the case of a 64-year-old man without hemorrhagic history experiencing epistaxis. The standard hemostasis assessment including prothrombin index, activated partial thromboplastin time (APTT) and platelet count found an isolated abnormal APTT (105 sec vs 33 sec). Therefore, coagulation factors were explored. An acquired factor VIII deficiency (5%) with anti-FVIII antibody (4.5 Bethesda unit.mL-1) was recognised. This anti-FVIII antibody was related to a Chlamydia pneumoniae pulmonary infection. Treatment consisted of: i) Four successive anterior packing and activated factor VII infusion (Novoseven); ii) steroids injection and bi-antibiotherapy. The time course of the epistaxis was favourable under treatment.

Anti-Inflammatory Agents↗
PubMed1998

Natural history of Epstein-Barr virus infection in a prospective pediatric cohort born to human immunodeficiency virus-infected mothers.

To determine whether Epstein-Barr virus (EBV) constitutes a contributing factor in AIDS and, conversely, whether the human immunodeficiency virus (HIV) alters the course of primary EBV infection in a pediatric population, 62 children born to HIV-infected mothers and prospectively followed were evaluated. EBV infection was documented by EBV-specific serology and polymerase chain reaction and by clinical history. HIV infection status was determined according to the Centers for Disease Control and Prevention pediatric classification system. Demographics from HIV-infected and HIV-uninfected children were comparable. The data suggest that HIV-infected children may acquire primary EBV infection earlier in life. The incidence of accompanying splenomegaly or hepatomegaly (or both) around the time of EBV seroconversion was higher among HIV-infected children than among HIV-uninfected children. In contrast, HIV disease progression and HIV-1 RNA load did not seem to be influenced by primary EBV infection.

AIDS-Related Opportunistic Infections↗
PubMed1996

Epstein-Barr virus transmission from a blood donor to an organ transplant recipient with recovery of the same virus strain from the recipient's blood and oropharynx.

A previous study (Savoie et al, Blood 83:2715, 1994) identified eight transplant patients who acquired Epstein-Barr virus (EBV) infection during the peritransplant period. Three of these patients subsequently developed B-cell lymphoproliferative disease within 4 months of transplantation. Among these, there was a 16-year-old liver transplant patient who was negative for EBV at the time of transplant and who received an EBV-negative organ. After transplant, this patient was transfused with 9 U of packed red blood cells. Eight of the donors were EBV-positive and one was EBV-negative. We succeeded in obtaining spontaneous lymphoblastoid cell lines (LCLs) from the blood of three of these donors, one of whom also yielded a cord-blood line established with his throat-wash EBV. Blood from a fourth donor did not yield an LCL, but his throat washing did have transforming activity when inoculated onto cord-blood leukocytes. We initially could establish spontaneous LCLs only from the recipient's blood. However, a throat-wash sample taken 11 weeks later did show transforming activity. The recipient was shown to have acquired the EBV infection from one of eight EBV-seropositive blood donors. Analysis of fragment length polymorphisms after polymerase chain reaction amplification of the EBV BamHI-K fragment was used to establish strain identity. Western blot analysis for existence of size polymorphisms in three classes of Epstein-Barr nuclear antigens (EBNA-1, EBNA-2, and EBNA-3) confirmed the DNA results. It is noteworthy that the blood donor responsible for transmitting his EBV strain to the recipient had experienced clinical infectious mononucleosis 15 months before donating blood. Our results may, thus, indicate a requirement for leukodepletion of blood destined for immunosuppressed EBV-negative patients. Finally, blood donors with a recent history of infectious mononucleosis should probably be identified so that their blood is not given to EBV-negative transplant patients.

Adolescent↗
PubMed1996

Antibody responses to two Epstein-Barr virus (EBV) nuclear antigens (EBNA-1 and EBNA-2) during EBV primary infection in children born to mothers infected with human immunodeficiency virus.

A variety of antibody response patterns to the latent Epstein-Barr nuclear antigen (EBNA) family have been described in different groups of subjects infected with Epstein-Barr virus (EBV). The purpose of this study was to characterize the immune response to two EBNA proteins, EBNA-1 and EBNA-2, in a population of children who were born to mothers infected with HIV and who underwent EBV seroconversion. Serial serum specimens from 33 children (nine were infected with HIV, and 24 were not infected) were evaluated for the presence of antibodies to EBNA-1 and EBNA-2 by anticomplement immunofluorescence. All the EBNA serology profiles observed for children in our study who were not infected with HIV were consistent with those described for immunocompetent hosts with acute EBV infection, i.e., development of antibodies to EBNA-1, often preceded by the appearance of a humoral immune response to EBNA-2. In contrast, following EBV primary infection in HIV-infected children, antibodies to EBNA-2 arose after antibodies to EBNA-1 and tended to persist. Further studies are needed to investigate the role of EBNA-2 serology as a prognostic marker in HIV-infected children.

Antibodies, Viral↗
PubMed1995

Choice of traditional or modern treatment in west Burkina Faso.

A recent survey shows that patients turn to modern medicine more than traditional medicine for most of their needs except rheumatic and neurological complaints. However, the preferences stated are influenced on the one hand by the much lower cost of traditional services, and on the other by official disapproval of animistic practices.

Adolescent↗
PubMed1994

Direct correlation between the load of Epstein-Barr virus-infected lymphocytes in the peripheral blood of pediatric transplant patients and risk of lymphoproliferative disease.

The Epstein-Barr virus (EBV) is known to cause posttransplant lymphoproliferative disease (PTLD) in immunosuppressed transplant patients. The results of this pilot study showed that all EBV- patients pretransplant experienced primary EBV infection within the first 3 months after transplant surgery. Virtually all of these patients had a higher burden of EBV-infected cells in their peripheral blood (PB) after infection by EBV than did the EBV+ pretransplant group when tested at the same intervals posttransplant. Salivary EBV titers also increased in most patients, but the difference between the two groups was statistically significant only at 12 months, whereupon EBV+ patients showed higher titers compared with EBV- (alpha < 0.053). Also, polymerase chain reaction amplification followed by Southern blotting was performed to detect EBV sequences in PB mononuclear cells. This technique allowed confirmation of the blood culture results and constituted a faster alternative compared with the culture assay. The highest increase in the number of EBV-infected lymphocytes at 3 months posttransplant obtained from PB was seen in a patient who developed fatal PTLD and in another with protracted infectious mononucleosis. Thus, the number of EBV-infected cells in PB was found to correlate positively with risk of development of PTLD at 3 months posttransplant in our group of pediatric transplant patients. This study showed that quantitative lymphocyte culture of PB was an accurate index of immunosuppression and a reliable method for assessing the risk of PTLD development.

Adolescent↗
PubMed1980

[Gestalt synergy.].

The author describes a new psychotherapeutic approach called Gestalt Synergy. After presenting it's originality among others Body/Mind approaches, the author retraces the history of it's development through the personal history of the founder of Gestalt Synergy : Ilana Rubenfeld. Then follows an introduction of the Alexander Technique and the Feldenkrais Method which, with Gestalt, inspired Gestalt Synergy. The concepts and techniques of Gestalt Synergy are discussed and, the sequence of one session is illustrated. The author concludes on some personal changes noted from her use of this approach.

English Abstract↗