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Biomedical subjects

J Joncas

Publications and source records attributed to J Joncas.

At least 19 recordsLinked to original sources
PubMed2002

Study of patient positioning on a dynamic frame for scoliosis surgery.

The goal of this clinical trial was to measure patient geometry on a dynamic positioning frame in various prone positions. Fourteen subjects (2 males and 12 females) were recruited from the scoliosis clinic at Ste-Justine Hospital on a volunteer basis. The subjects were AIS patients who were potential candidates for surgery. The Cobb angle, averaged 50 degrees (32 degrees-64 degrees). The mean age was 14.1 years (11-17). A Polaris system (Northern Digital inc, Canada) with 10 passive reflective markers was used to measure various indices of the patient's trunk geometry. Acquisitions were made while the unanaesthetized patient was in five different prone positions: I similar to the standard positioning on a Relton-Hall frame; II addition of a force applied to the ribcage at the apex of the curve; III application of a force at the apex of the curve in the lumbar region; IV, the shoulder pads were elevated to increase the patient's kyphosis; V adjustment of each pad and the application of thoracic and lumbar forces to obtain an optimal correction. The measurements of trunk geometry at each position were compared using position I as a base. A paired student t-test determined a significant difference between positions. When comparing position I to position II there was a significant difference and correction of the rib hump. There was also a significant change in shoulder angle that resulted in over correction. Position III had a significantly negative change in the rib hump. During position IV, there was a measurable increase in kyphosis. During the optimal correction, position V, a significant increase in spine length was observed as well as a significant correction in rib hump and shoulder angle. Patient trunk geometry can be improved by the application of different forces on a dynamic positioning frame. Caution is necessary as over correction and unintended negative effects were observed. The optimal patient position has not yet been found and future studies are directed at determining this.

Adolescent↗
PubMed1999

Variability of strap tension in brace treatment for adolescent idiopathic scoliosis.

STUDY DESIGN: A mechanical evaluation of brace strap tensions to document their variability in different patient positions and to assess their biomechanical effectiveness. OBJECTIVES: To measure the strap tensions at which adolescents with scoliosis are wearing their braces and to determine the variations in strap tension in different patient positions. SUMMARY OF BACKGROUND DATA: The biomechanical action of thoracolumbosacral orthoses in still not well understood, and there is no standardized strap tension at which the brace should be fastened to obtain optimal results. METHODS: This study was conducted in 34 adolescents with idiopathic scoliosis wearing thoracolumbosacral orthoses. Brace straps were instrumented with load cells and tightened at four tensions (the ones prescribed by their treating physician and three standardized values: 20, 40, and 60 N). In each case, the tension was recorded while the patients assumed nine positions corresponding to normal daily tasks. The variability of strap tension was evaluated by comparing the changes from the original standing position. RESULTS: The prescribed tensions measured in thoracic and pelvic straps were markedly variable. The greatest changes in tension occurred when the patients were lying down. Relaxation of strap tension was found when the patients returned to the standing position after having completed the tasks. CONCLUSIONS: If strap tension affects the biomechanical actions of the brace, these results indicate that regular brace strap tension adjustments are needed and raise questions about the efficacy of nighttime bracing to correct spinal deformities.

Adolescent↗
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↗
PubMed1996

[Herniated disk and congenital spinal stenosis in the adolescent].

PURPOSE OF THE STUDY: The goal of this study was to demonstrate the relationship between herniated discs and congenital spinal stenosis. A retrospective study was conducted on patients seen in our center over a five year period. MATERIAL AND METHODS: The CT-Scan evaluation was essential for the measurement of the diameter of the spinal canal. Data were compared with the values obtained in ten normal subjects. RESULTS: Twelve complete charts of adolescents with herniated discs were reviewed and in all cases a spinal stenosis was established. The mean diameter of the canal was 8.1 mm for the patient group compared with 18.1 mm for the control group. CONCLUSION: The relationship of herniated discs and spinal stenosis found here is greater than the one reported in the literature. This relationship accounts for the importance of neurological (9/12 patients) involvement found in our series in comparison with adults. This also explains the failure of conservative treatment.

Adolescent↗
PubMed1996

[Dorso-lumbal pain and idiopathic scoliosis in adolescence].

Current knowledge on the association between back pain and idiopathic scoliosis is often contradictory. The presence, localisation and importance of pain was evaluated for a cohort of 426 adolescents with AIS. Patients were recruited from a scoliosis clinic in a pediatric hospital. A questionnaire and an analogue visual scale graduated from 0 (no pain) to 100 (maximal pain) were used in order to verify more precisely, the importance of the association between AIS and back pain. Chisquare, linear regression and Student T-test were used for statistical analysis. 239 patients with right thoracic and left lumbar curves (RTLL) had a prevalence of pain of 54%. The mean of maximum pain intensity was 49 mm +/- 20. No relation was found between the severity of the scoliosis and back pain. The two groups (with and without pain) were comparable. Cobb angles were about the same for the thoracic and lumbar regions, as well as kyphosis and lordosis, weight, height and age. Risser sign, sex, brace and pelvic tilt were the only variables associated with pain (p < 0.0001). Association between AIS and pain is more frequent than generally reported. Pain appears to be more related with pelvic tilt than severity of the scoliosis.

Adolescent↗
PubMed1995

Natural history of muscle weakness in Friedreich's Ataxia and its relation to loss of ambulation.

From 1979 to 1992, 170 muscular assessments performed on 33 patients with Friedreich's Ataxia were reviewed. The average followup was 6 years. All muscle evaluations were done by the same team. It was possible to delineate a fairly regular and statistically significant pattern of slowly progressive and symmetrical loss of strength affecting mainly the lower limbs, and more specifically the pelvic girdle muscles. The first significant weakness was observed in the hip extensor group, followed in a variable fashion by other muscle groups of the lower limb. Upper limb and trunk muscles remained relatively spared until late in the disease process, with an overall strength approximately 80% of normal. Use of a wheelchair began at a mean age of 18.2 years, at which time the lower-limb strength averaged 70% of normal. Patients became totally unable to walk at a mean of age 20.5 years old, with a further decline in lower limb strength to 56% of normal. Weakness does not appear to be the primary cause for loss of ambulation in patients with Friedreich's ataxia.

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↗
PubMed1994

Comparison of novel synthetic peptide-based DETECT-RUBELLA enzyme immunoassays with Enzygnost and IMx for detection of rubella-specific immunoglobulin G.

Enzyme immunoassays (EIAs) using synthetic peptides SP-E1 and SP-E1E2 (DETECT-RUBELLA [Bio-Chem]) were compared with two viral lysate-based EIAs (Enzygnost [Behring] and IMx [Abbott]) for the detection of rubella virus-specific immunoglobulin G antibodies. Sensitivities of 94.7, 100, 98.6, and 100% and specificities of 100, 97.4, 100, and 73.7% were found for the SP-E1, SP-E1E2, Enzygnost, and IMx EIAs, respectively.

Antibodies, Viral↗
PubMed1993

Comparison of four enzyme immunoassays for the detection of cytomegalovirus IgG antibodies.

Four commercial enzyme immunoassays (EIA), namely the Behring Enzygnost EIA (BE-EIA), Abbott IMx, Whittaker CMV STAT Test Kit and Diamedix assay, were evaluated for the detection of CMV IgG. The methods were compared as to sensitivity, specificity, positive and negative predictive values, global agreement, ease of performance and, for a small number of specimens, reproducibility. Discordant results were resolved by using the Gull CMV indirect fluorescent antibody (IFA) method. Our data suggest that all four assays were valuable screening tools for the detection of CMV IgG based on their high sensitivity and high negative predictive value. However, differences were noted in the reproducibility level and in the incidence of false-positive, equivocal and nonspecific results regarding certain tests in particular. In our hands, the Abbott IMx and the BE-EIA ranked high in the performance characteristics for a good screening test, yet the Abbott IMx offers the added advantages of being the easiest to perform and having the most rapid turnaround time.

Journal Article↗
PubMed1992

Lack of scientific evidence for the treatment of lateral epicondylitis of the elbow. An attempted meta-analysis.

We have reviewed 185 articles published since 1966 to assess the scientific evidence for methods of treatment for lateral epicondylitis of the elbow. Of the 185 articles, 78 discussed treatment, but since the natural history of the syndrome is uncertain we considered only those series with concurrent control groups. Only 18 of these were randomised and controlled studies. We then graded these papers for scientific validity, using the methods of Chalmers et al (1981). The mean score of the 18 articles was only 33%, with a range from 6% to 73%. A minimum of 70% is required for a valid clinical trial, and we therefore concluded that there was insufficient scientific evidence to support any of the current methods of treatment. There were too many methodological differences to allow a quantitative meta-analysis, but our qualitative review established the importance of the natural evolution of the syndrome and of the placebo effect of all treatments. Properly designed, controlled trials are needed.

Acute Disease↗
PubMed1991

Lack of effect of peroral acyclovir for the treatment of acute infectious mononucleosis.

Perorally administered acyclovir was evaluated in the therapy of acute infectious mononucleosis in a multicentered, randomized, double-blind, placebo-controlled trial. A total of 120 patients received 600 mg of acyclovir or placebo five times daily for 10 days. All patients were entered into the study within 7 days of symptom onset and had a positive Monospot test. Analysis of mean values and time to resolution of fever, lymphadenopathy, weight change, hepatomegaly, splenomegaly, liver function tests, atypical lymphocytes, hours of bed rest, sense of well-being, and return to normal activities revealed no significant differences. There was a trend toward suppression of Epstein-Barr virus excretion in the oropharynx in acyclovir recipients. No toxicity was detected in patients treated with acyclovir. Under the conditions of the study, there was no evidence that treatment with perorally administered acyclovir affected the course of infectious mononucleosis.

Acyclovir↗
PubMed1989

Brief report: killer cell defect and persistent immunological abnormalities in two patients with chronic active Epstein-Barr virus infection.

Two members of a family have manifested a syndrome of chronic active Epstein-Barr virus (EBV) infection. A father and his daughter suffered prolonged or recurrent mononucleosis, with splenomegaly, anemia, and intermittent fever; persistent immunological abnormalities included defective natural killer (NK) cytotoxicity, inverted CD4/CD8 ratios, hyper IgG1, high EBV viral capsid antigen (VCA) and early antigen (EA) antibodies, and low or undetectable EBV nuclear antigen (EBNA) antibody titers. The EBV seronegative member of the family was free of these abnormalities. However, NK activity in the seronegative individual was low-normal and its EBV-specific antibody-dependent K-cell cytotoxicity (EBV-ADCC) was abnormally low, suggesting that this K-NK cell defect may be primary. The father, who suffered from the syndrome for more than 15 years, lacked (or lost) antibodies to EBV-envelope and infected cell membranes, such as antibody-dependent cellular cytotoxicity (ADCC), neutralizing (NT), and gp 350/220 antibodies. Slow improvement over a period of years was heralded by rising NK cytotoxicity.

Adolescent↗
PubMed1987

Epstein-Barr virus related lymphoepithelioma-like carcinoma of lung.

A malignant neoplasm localized to the lung is reported in a rather unusual host: a 40-year-old female, nonsmoker, of South-East Asiatic origin. The histology was of nasopharyngeal-like carcinoma character and ultrastructural examination confirmed a diagnosis of nonkeratinizing, poorly differentiated squamous cell carcinoma. The clinicopathologic findings were more suggestive of a primary pulmonary origin than the manifestation of an occult nasopharyngeal primary. The immunological profile was highly suggestive of an Epstein-Barr virus (EBV) associated epithelial neoplasia. This case might widen the spectrum of EBV-associated neoplasia, by inclusion of lower respiratory tract as a target organ.

Adult↗