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Biomedical subjects

L Bergeron

Publications and source records attributed to L Bergeron.

At least 37 records · Page 2Linked to original sources
PubMed1996

Effects of human immunodeficiency virus type 1 infection on programmed cell death in the presence or absence of Bcl-2.

The effect of human immunodeficiency virus (HIV-1) infection on the programmed cell death of CD4+ lymphocytes was studied by using Jurkat cells stably expressing high levels of the Bcl-2 protein (Jurkat-Bcl2) or control cells (Jurkat-P). Both Jurkat-Bcl2 and Jurkat-P cells exhibited surface CD4 expression adequate to support HIV-1 infection. We observed no differences between HIV-1-infected Jurkat Bcl2 cells and control cells with respect to kinetics of virus replication, protein expression, and processing. Severe cytopathic effects, which were typical of acute HIV-1 infection and consisted of syncytium formation followed by single-cell lysis, were observed in both cell types. However, several lines of evidence, such as cell viability analysis by trypan blue dye exclusion, chromosomal DNA laddering, and morphologic analysis by acridine orange/ethidium bromide or Giemsa staining, indicated that HIV-1 did not induce a significant amount of programmed cell death in either cell type. These results suggest that apoptosis is at most a minor element in HIV-1-induced cytopathicity in Jurkat lymphocytes.

Apoptosis↗
PubMed1995

Do children aged 9 through 11 years understand the DISC Version 2.25 questions?

OBJECTIVE: To assess the understanding of Diagnostic Interview Schedule for Children-Version 2.25 (DISC-2.25) questions by children aged 9 through 11 years. METHOD: Two hundred forty children were recruited from four public schools. The cognitive appraisal of 280 questions from the most prevalent DSM-III-R diagnoses was evaluated. The collaboration of four children was necessary to cover one DISC. Sixty DISCs, evenly distributed according to age and sex, were completed. Two child psychiatrists evaluated the children's answers. Nonparametric tests were used to assess understanding of questions as a whole, of time concepts (overall, categories, number), and of questions based on the number of words. RESULTS: Children aged 9, 10, and 11 years understood 38%, 38%, and 42% of the questions as a whole, respectively, and 26%, 24%, and 30% of the overall time concepts, respectively. The understanding rates of questions as a whole were significantly higher than those of overall time concepts. Durations were significantly better understood than periods and frequencies, and questions having one time component were significantly better grasped than those with two or more. Shorter questions were significantly better understood than longer ones. CONCLUSION: Although the DISC has been greatly improved since the initial version, the results suggest that additional revision is needed before clinicians or researchers use the DISC with younger children.

Bias↗
PubMed1994

Ich-1, an Ice/ced-3-related gene, encodes both positive and negative regulators of programmed cell death.

We report here the isolation and characterization of Ich-1, a gene related to the C. elegans cell death gene ced-3 and the mammalian homolog of ced-3, interleukin-1 beta-converting enzyme (ICE). Alternative splicing results in two distinct Ich-1 mRNA species. One mRNA species encodes a protein product of 435 amino acids (ICH-1L) that is homologous to both the P20 and P10 subunits of ICE (27% identity) and the entire CED-3 protein (28% identity). The other mRNA encodes a 312 amino acid truncated version of ICH-1L protein (ICH-1S). Overexpression of IchL induces programmed cell death, suggesting that Ich-1 is also a mammalian programmed cell death gene. More interestingly, overexpression of the Ich-1S suppresses Rat-1 cell death induced by serum deprivation. These observations suggest that Ich-1 plays an important role in both positive and negative regulation of programmed cell death in vertebrate animals.

Alternative Splicing↗
PubMed1994

A structured pictorial questionnaire to assess DSM-III-R-based diagnoses in children (6-11 years): development, validity, and reliability.

This paper presents a structured pictorial instrument, the Dominic questionnaire, to assess mental disorders in 6- to 11-year-old children. Ninety-nine drawings represent situations corresponding to DSM-III-R based ADHD, CD, ODD, MDD, SAD, OAD, and SPh. However, cognitive limitation of 6- to 11-year-old children do not allow for time-related measurement. The instrument takes 15-20 min to administer. Reliability and validity of the Dominic questionnaire were studied in Parent DISC-2 positive and negative outpatient and general population samples and against clinical judgement. The pictorial approach provides acceptable test-retest reliability and the instrument makes standardized assessment possible for children as young as 6 years of age.

Age Factors↗
PubMed1994

An empirical comparison between the DSM and psychodynamic approaches for assessment of child disorders in children attending outpatient clinics.

The DSM and psychodynamic approaches provide different perspectives on child psychiatric diagnoses. Taking advantage of the recent publication of a psychodynamically oriented classification of child disorders, correspondences between these approaches were studied in a sample of outpatient clinic children. Clinician judges and a psychiatric interview schedule provided for diagnoses. Classifications of child psychopathology are still imperfect to a large extent. As a result, statistical comparisons can only yield limited relationships and caution is necessary when using classification tools. Methodological difficulties notwithstanding, various associations showed that DSM and psychodynamic constructs, while different, are not entirely independent.

Affective Symptoms↗
PubMed1994

Possible red-man syndrome associated with systemic absorption of oral vancomycin in a child with normal renal function.

OBJECTIVE: To report possible red-man syndrome (RMS) associated with oral administration of vancomycin. CASE SUMMARY: A 23-month-old child with acute myeloblastic leukemia developed symptoms compatible with RMS while receiving oral vancomycin for suspected Clostridium difficile colitis. Serum concentrations of vancomycin, measured at the time of the clinical episode, demonstrated significant oral absorption of the drug. Serum concentrations of vancomycin decreased later, implying a possible decrease in absorption, after the patient's neutrophil count returned to normal. The child later experienced another clinical episode compatible with RMS while vancomycin was being administered intravenously for suspected sepsis. DISCUSSION: There is no published report of RMS following oral administration of vancomycin. The reaction described took place while the child was neutropenic. Because of the absence of any significant renal function alteration that could explain the importance of the serum concentrations observed, we assume that C. difficile, neutropenia-, and chemotherapy-associated colitis may have resulted in extensive intestinal lesions, leading to an increased amount of vancomycin being systemically absorbed. This increased absorption during profound neutropenia may have been sufficient to exceed a purported threshold, leading to RMS. CONCLUSIONS: This case demonstrates that significant absorption of vancomycin may occur in neutropenic patients with normal renal function, and that it may be accompanied by RMS, usually associated with rapid infusions or large parenteral doses of the drug.

Administration, Oral↗
PubMed1993

Effects of amino acid changes in the extracellular domain of the human immunodeficiency virus type 1 gp41 envelope glycoprotein.

Changes were introduced into conserved amino acids within the ectodomain of the human immunodeficiency virus type 1 (HIV-1) gp41 transmembrane envelope glycoprotein. The effect of these changes on the structure and function of the HIV-1 envelope glycoproteins was examined. The gp41 glycoprotein contains an amino-terminal fusion peptide (residues 512 to 527) and a disulfide loop near the middle of the extracellular domain (residues 598 to 604). Mutations affecting the hydrophobic sequences between these two regions resulted in two phenotypes. Some changes in amino acids 528 to 562 resulted in a loss of the noncovalent association between gp41 and the gp120 exterior glycoprotein. Amino acid changes in other parts of the gp41 glycoprotein (residues 608 and 628) also resulted in subunit dissociation. Some changes affecting amino acids 568 to 596 resulted in envelope glycoproteins partially or completely defective in mediating membrane fusion. Syncytium formation was more sensitive than virus entry to these changes. Changes in several amino acids from 647 to 675 resulted in higher-than-wild-type syncytium-forming ability. One of these amino acid changes affecting tryptophan 666 resulted in escape from neutralization by an anti-gp41 human monoclonal antibody, 2F5. These results contribute to an understanding of the functional regions of the HIV-1 gp41 ectodomain.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Informants, correlates and child disorders in a clinical population.

This paper examines associations between informants, correlates and child disorders in a sample of 230 outpatients six to 14 years of age. K-SADS-E diagnoses and scores were studied according to informant, gender, age group, mental health of the parents, life events and parents' relationship. The results show that parents underreport their daughters' internalized disorders compared with reports of children and adolescents and that male children and adolescents underreport all types of disorders compared with the reports of their parents. Intra-informant correlations and differences between informants suggest an uneven influence according to informants of correlates on the report of child disorders.

Adolescent↗
PubMed1992

Dissociation of unintegrated viral DNA accumulation from single-cell lysis induced by human immunodeficiency virus type 1.

Acute cytopathic retroviral infections are accompanied by the accumulation, due to superinfection, of large amounts of unintegrated viral DNA in the cells. The cytopathic effects of human immunodeficiency virus type 1 (HIV-1) infection are specific for cells that express the CD4 viral receptor and consist of syncytium formation and single-cell lysis. Here we investigated the relationship between superinfection and single-cell lysis by HIV-1. Antiviral agents were added to C8166 or Jurkat lymphocytes after HIV-1 infection had occurred. Treatment with azidothymidine or a neutralizing anti-gp120 monoclonal antibody reduced or eliminated, respectively, the formation of unintegrated viral DNA but did not inhibit single-cell killing. Furthermore, in the infected Jurkat cells, the levels of unintegrated viral DNA peaked several days before significant single-cell lysis was observed. Essentially complete superinfection resistance was established before the occurrence of single-cell killing. These results demonstrate that single-cell lysis by HIV-1 can be dissociated from superinfection and unintegrated viral DNA accumulation. These results also indicate that single-cell killing may involve envelope glycoprotein-receptor interactions not accessible to the exterior of the cell.

Antibodies, Monoclonal↗
PubMed1992

Target cell-specific determinants of membrane fusion within the human immunodeficiency virus type 1 gp120 third variable region and gp41 amino terminus.

The entry of human immunodeficiency virus type 1 (HIV-1) into target cells involves binding to the viral receptor (CD4) and membrane fusion events, the latter influenced by target cell factors other than CD4. The third variable (V3) region of the HIV-1 gp120 exterior envelope glycoprotein and the amino terminus of the HIV-1 gp41 transmembrane envelope glycoprotein have been shown to be important for the membrane fusion process. Here we demonstrate that some HIV-1 envelope glycoproteins containing an altered V3 region or gp41 amino terminus exhibit qualitatively different abilities to mediate syncytium formation and virus entry when different target cells are used. These results demonstrate that the structure of these HIV-1 envelope glycoprotein regions determines the efficiency of membrane fusion in a target cell-specific manner and support a model in which the gp41 amino terminus interacts directly or indirectly with the target cell during virus entry.

Amino Acid Sequence↗
PubMed1992

Pilot study for the Quebec Child Mental Health survey: Part I. Measurement of prevalence estimates among six to 14 year olds.

A pilot study for a Quebec Child Mental Health Survey was completed in 1990 with 139 children aged six to 14 years from the general population. Six month prevalence estimates for seven disorders were established using DSM-III-R criteria alone and in combination with an impairment index related to the diagnoses. Prevalence estimates were studied separately for parents and children. Each age group (six to 11, 12 to 14) was also studied separately. The impairment index, working as a severity scale, lowered prevalence estimates and allowed identification of impairing and non impairing diagnoses. Little overlap was found between informants.

Adolescent↗
PubMed1992

Pilot study for the Quebec Child Mental Health Survey: Part II. Correlates of DSM-III-R criteria among six to 14 year olds.

A pilot study for a Quebec Child Mental Health Survey was completed in 1990 with 139 six to 14 year olds from the general population. The following variables, which were correlated with child psychopathology, were studied for each age group (six to 11 years, 12 to 14 years) and informant (parent, child): child's gender and stressful life events, respondent parent's psychiatric illness, family structure, parent-child relationships, parents' relationship, socioeconomic status, respondent parent's social desirability. Correlations obtained are consistent with those found in the literature. Correlations between the parent's mental health, parent-child relationships and the children's mental health are the most important results of the study.

Age Factors↗
PubMed1991

Attenuation of human immunodeficiency virus type 1 cytopathic effect by a mutation affecting the transmembrane envelope glycoprotein.

The cytopathic effects of human immunodeficiency virus type 1 (HIV-1) infection are specific for cells that express the CD4 viral receptor and consist of syncytium formation and single-cell lysis. Here we report that a mutation (517A) affecting the amino terminus of the HIV-1 gp41 transmembrane envelope glycoprotein resulted in a virus that was markedly less cytopathic than was wild-type HIV-1. In systems in which cell-to-cell transmission of HIV-1 occurred, the replication ability of the 517A virus was comparable with that of the wild-type virus. Even though the levels of viral protein expression, virion production, and interaction of the envelope glycoproteins with CD4 were similar for the 517A and wild-type viruses, both syncytium formation and single-cell lysis were attenuated for the 517A mutant virus. These results demonstrate that an envelope glycoprotein region important for mediating post-receptor binding events in cell membrane fusion is important for the induction of cytopathic effects by HIV-1. These results also indicate that levels of HIV-1 viral proteins or viral particles produced in infected cells are in themselves not sufficient to induce cytopathic effects.

Amino Acid Sequence↗
PubMed1991

Gene transfer into human lymphocytes by a defective human immunodeficiency virus type 1 vector.

Human immunodeficiency virus type 1 (HIV-1) proviruses containing deletions between nucleotides 301 and 319 express viral proteins but exhibit marked attenuation in the packaging of viral RNA into virions (A. Lever, H. Gottlinger, W. Haseltine, and J. Sodroski, J. Virol. 63:4085-4087, 1989; A. Aldovini and R. A. Young, J. Virol. 64:1920-1926, 1990). Here we report that such packaging-defective proviruses can provide trans-acting viral elements required for the transfer of a HIV-1 vector to Jurkat human lymphocytes. The transferred vector was unable to encode HIV-1 genes, indicating that the long terminal repeats and the immediate flanking viral sequences are sufficient for packaging, reverse transcription, and integration. The generation of replication-competent viruses in this system was reduced to undetectable levels by providing the trans-acting viral functions on two separate expression plasmids. This defective retroviral vector provides a means of efficiently introducing desired genetic elements, in the absence of HIV-1 genes, into HIV-1 target cells.

Animals↗
PubMed1988

Thyrotoxic periodic paralysis.

We present the case of a 21-year-old man who presented to the emergency department with an episode of profound weakness due to thyrotoxic periodic paralysis, a syndrome of muscular weakness occurring in patients with hyperthyroidism. Prior to the diagnosis, the patient was treated with a parenteral tranquilizer. When hypokalemia was discovered, potassium was administered, resulting in the development of hyperkalemia. Episodes of thyrotoxic periodic paralysis are usually self limited, and recovery of motor strength is complete. However, potassium is frequently administered to hasten recovery and prevent cardiac arrhythmias and respiratory arrest. Serum potassium must, therefore, be monitored carefully in these patients during treatment.

Adult↗
PubMed1987

Dopamine D2 receptor binding in adrenal medulla: characterization using [3H]spiperone.

The possibility that dopamine may function as a neuromodulator or neurotransmitter in the adrenal gland, and not merely serve as a precursor to the catecholamines, has been suggested. If this hypothesis is correct, receptors for dopamine should be identifiable in the adrenal. The present work demonstrates the existence of a high-affinity receptor in adrenal medulla using [3H]spiperone as the radioligand to label the receptors. [3H]Spiperone bound rapidly, reversibly, and with high affinity to bovine adrenal medullary membranes. Scatchard analysis yielded a Kd of 0.09 nM and a Bmax of 51 fmol/mg protein. In competition binding experiments, dopaminergic antagonists were at least 100 times more potent in displacing [3H]spiperone from its binding sites than adrenergic or serotonergic receptor antagonists. Similarly, agonists at the dopamine receptor more readily competed for [3H]spiperone binding than other receptor agonist drugs tested. Furthermore, D2 selective antagonists and agonists were much more potent than D1 receptor ligands. These results suggest that [3H]spiperone may bind to a high-affinity D2 dopamine receptor in adrenal medulla.

Adrenal Medulla↗
PubMed1984

[Suicidal ideation and behavior of young college students in Montréal.].

Suicide among youth is a subject of growing concern. Successful suicides, however, represent only a slight part of the total problem. A study conducted with 666 francophones students attending four C.E.G.E.P. in the Montreal territory reveals that 21.2 % of them say that they have already experienced serious suicidal ideation. 12.2 % have had these experiences within the last twelve months. There are also 3.6 % of the students who admitted to having attempted suicide during the same period, and 8.1 % during their lifetime. More than half of the students say they also have experienced suicidal obsessions such as a fear or a desire to throw themselves in front of the metro. Parental separation and poor health represent the two most serious risk factors. Nearly three quarters of the people who have had serious suicidal thoughts have thought of plans or have confided them to members of their social circle... The reaction of the milieu was reported as positive in only half the cases. Clinical interviews with 25 of the respondents showed that the suicidal ideation reported, corresponded, in almost all cases, with a period of great anguish. The fact of thinking of suicide did have, on the other hand, some positive effects in producing awareness of the possibility of a control over one's destiny.

English Abstract↗