PubMed Health⌕ Search

Biomedical subjects

M Libman

Publications and source records attributed to M Libman.

12 recordsLinked to original sources
PubMed2004

Measles vaccination in the presence of maternal antibodies primes for a balanced humoral and cellular response to revaccination.

Early or low dose antigen exposure can prime the immune system for subsequent responses; the so-called "prime-boost" effect. In the context of a Sudanese measles vaccine trial, we assessed whether or not such early exposure could influence the response to revaccination. Children received either Connaught high titer vaccine (CN: n = 53; 10(4.7)pfu) or meningococcal A + C vaccine as a placebo (MEN: n = 58) at 5 months of age. At 9 months of age, all received standard titer Schwarz vaccine (SCH: 10(3.9)pfu). Neutralizing antibodies were measured before initial vaccination and at 9 months of age (plaque reduction neutralization assay (PRN)) and again at 5 years of age (syncytium inhibition assay (SIA)). Lymphoproliferative responses to measles virus (MV) antigens were evaluated at 5 years of age. Eleven of the 53 CN-SCH children (21%) had sub-protective neutralizing antibody titers prior to revaccination (log PRN 1.5 +/- 0.03 versus 2.9 +/- 0.07 in the remaining 42 children; P < 0.004). Maternal antibody titers at the time of initial vaccination in these 11 were high (PRN 2.44 +/- 0.12 versus 1.9 +/- 0.04; P < 0.0001). At 5 years of age, neutralizing antibodies were comparable in the 11 CN-SCH poor responders (log SIA 2.1 +/- 0.09), the remaining CN-SCH children (2.2 +/- 0.06) and the MEN-SCH group vaccinated only once at 9 months of age (2.25 +/- 0.06). In contrast, 7/11 of the CN-SCH poor responders (64%) had stimulation indices (SI) > 3 in response to MV antigens at 5 years of age (SI 3.1 +/- 0.6) compared with only 14% in the remaining children of the CN-SCH group (2.0 +/- 0.3; P = 0.05) and 8% in the MEN-SCH group (1.4 +/- 0.2; P < 0.0003). These data suggest that early measles vaccination in the presence of maternal antibodies can sometimes prime for a balanced humoral and cellular immune response to subsequent revaccination.

Age Factors↗
PubMed2001

Socio-economic disparities in preterm birth: causal pathways and mechanisms.

Preterm birth is the leading cause of infant mortality in industrialised societies. Its incidence is greatly increased among the socially disadvantaged, but the reasons for this excess are unclear and have been relatively unexplored. We hypothesise two distinct sets of causal pathways and mechanisms that may explain social disparities in preterm birth. The first set involves chronic and acute psychosocial stressors, psychological distress caused by those stressors, increased secretion of placental corticotropin releasing hormone (CRH), changes in sexual behaviours or enhanced susceptibility to bacterial vaginosis and chorioamnionitis, cigarette smoking or cocaine use, and decidual vasculopathy. The second hypothesised pathway is a gene-environment interaction based on a highly prevalent mutation in the gene for methylenetetrahydrofolate reductase (MTHFR), combined with low folate intake from the diet and from prenatal vitamin supplements, consequent hyperhomocysteinemia, and decidual vasculopathy. We propose to test these hypothesised pathways and mechanisms in a nested case-control study within a prospectively recruited and followed cohort of pregnant women with singleton pregnancies who deliver at one of four Montreal hospitals that serve an ethnically and socio-economically diverse population. Following recruitment during the late first or early second trimester, participating women are seen at 24-26 weeks, when a research nurse obtains a detailed medical and obstetric history; administers several scales to assess chronic and acute stressors and psychological function; obtains blood samples for CRH, red blood cell and plasma folate, homocysteine, and DNA for the MTHFR mutation; and performs a digital and speculum examination to measure cervical length and vaginal pH and to obtain swabs for bacterial vaginosis and fetal fibronectin. After delivery, each case (delivery at < 37 completed weeks following spontaneous onset of labour or prelabour rupture of membranes) and two controls are selected for placental pathological examination, hair analysis of cotinine, cocaine, and benzoylecgonine, and analysis of stored blood and vaginal specimens. Statistical analysis will be based on multiple logistic regression and structural equation modelling, with sequential construction of models of potential aetiological determinants and covariates to test the hypothesised causal pathways and mechanisms. The research we propose should improve understanding of the factors and processes that mediate social disparities in preterm birth. This improved understanding should help not only in developing strategies to reduce the disparities but also in suggesting preventive interventions applicable across the entire socio-economic spectrum.

Adult↗
PubMed2001

Prevalence and antifungal susceptibility of 442 Candida isolates from blood and other normally sterile sites: results of a 2-year (1996 to 1998) multicenter surveillance study in Quebec, Canada.

During a 2-year surveillance program (1996 to 1998) in Quebec, Canada, 442 strains of Candida species were isolated from 415 patients in 51 hospitals. The distribution of species was as follows: Candida albicans, 54%; C. glabrata, 15%; C. parapsilosis, 12%; C. tropicalis, 9%; C. lusitaniae, 3%; C. krusei, 3%; and Candida spp., 3%. These data, compared to those of a 1985 survey, indicate variations in species distribution, with the proportions of C. glabrata and C. parapsilosis increasing by 9 and 4%, respectively, and those of C. albicans and C. tropicalis decreasing by 10 and 7%, respectively. However, these differences are statistically significant for C. glabrata and C. tropicalis only. MICs of amphotericin B were > or =4 microg/ml for 3% of isolates, all of which were non-C. albicans species. Three percent of C. albicans isolates were resistant to flucytosine (> or =32 microg/ml). Resistance to itraconazole (> or =1 microg/ml) and fluconazole (> or =64 microg/ml) was observed, respectively, in 1 and 1% of C. albicans, 14 and 9% of C. glabrata, 5 and 0% of C. tropicalis, and 0% of C. parapsilosis and C. lusitaniae isolates. Clinical data were obtained for 343 patients. The overall crude mortality rate was 38%, reflecting the multiple serious underlying illnesses found in these patients. Bloodstream infections were documented for 249 patients (73%). Overall, systemic triazoles had been administered to 10% of patients before the onset of candidiasis. The frequency of isolation of non-C. albicans species was significantly higher in this group of patients. Overall, only two C. albicans isolates were found to be resistant to fluconazole. These were obtained from an AIDS patient and a leukemia patient, both of whom had a history of previous exposure to fluconazole. At present, it appears that resistance to fluconazole in Quebec is rare and is restricted to patients with prior prolonged azole treatment.

Amphotericin B↗
PubMed1999

Mycobacterium ulcerans infection (Buruli ulcer): first reported case in a traveler.

A chronic, painless sore developed over a 2-month period on the left calf of a Canadian man traveling for 8 months in Africa. A presumptive diagnosis of a Mycobacterium spp. infection was made despite initially negative biopsy and culture results, after failure of several courses of anti-bacterial antibiotics. Mycobacterium ulcerans was eventually isolated and the lesion progressed despite treatment with multiple anti-mycobacterial agents. The lesion finally responded to wide and repeated excision, aggressive treatment with anti-mycobacterial antibiotics, and split-thickness skin grafting. The isolation and treatment of this unusual organism are discussed.

Adult↗
PubMed1998

Screening returning travelers.

Posttravel screening is the clinical and laboratory assessment of an individual aimed at uncovering occult infections, pathology, or health risks, the treatment of which will yield a significant health benefit to the individual. Screening must be tailored to the different risk patterns associated with different travel categories (e.g., missionary, tourist). Screening, predominantly a secondary prevention strategy, is most cost-effective when integrated with primary prevention strategies aimed at preventing future travel related illness (Table 6). The screening process begins with a medical history that allows a definition of risks and a tailored approach to laboratory tests. The screening tests currently available for STDs, tuberculosis, and parasitic infections have been reviewed, and although cost-effectiveness data are not available for most post-travel screening tests, recommended approaches are proposed. Traditionally, screening has been directed at uncovering occult infectious disease (STDs, tuberculosis, and parasitic infections). Important benefits can be gained, however, by including screening questions and tests for those diseases that are the major causes of mortality, both in nontraveling and in traveling North Americans, that is, the atherosclerotic and neoplastic diseases and trauma, especially vehicular.

Feces↗
PubMed1998

False-positive enzyme immunoassay test results for Chlamydia trachomatis because of contact of the collection swab with agar.

BACKGROUND: We noted an increased incidence of false-positive Chlamydia trachomatis enzyme immunoassay results using the Abbott IMx SELECT C. trachomatis EIA test when a single swab was used for urethral sampling for both gonococcal culture inoculation and chlamydial detection. GOALS: To evaluate if contact of the enzyme immunoassay collection swab with an agar produces false-positive chlamydial enzyme immunoassay results. STUDY DESIGN: Samples containing agar-based culture media were tested by two enzyme immunoassays and a ligase chain reaction technique. RESULTS: We report false-positive chlamydial enzyme immunoassay results using the Abbott IMx SELECT C. trachomatis EIA test if the collection swabs are in contact with gonococcal culture media (Modified New York City agar, chocolate, Thayer-Martin, or GC-lect) before insertion of the swab in the transport media of the enzyme immunoassay. The other assay results were negative. CONCLUSIONS: Using a single collection swab to screen for genital infections with gonococcal cultures and chlamydial enzyme immunoassay is inappropriate because it may lead to false-positive chlamydial enzyme immunoassay results, at least with the Abbott IMx SELECT C. trachomatis EIA test, incurring public health and financial consequences.

Agar↗
PubMed1993

Disseminated infection after intravesical BCG immunotherapy. Detection of organisms in pulmonary tissue.

A 57-year-old man undergoing intravesical immunotherapy with BCG for transitional cell bladder carcinoma presented with dyspnea, fever, hypoxemia, and a diffuse micronodular pattern on chest radiograph. Transbronchial biopsy specimen revealed widespread noncaseating granulomas, and acid-fast bacilli were identified in sputum as well as in the biopsy tissue. The patient's condition responded promptly to antituberculous antibiotics given in conjunction with corticosteroids. Although no growth was evident on TB culture of the specimens, the presence of organisms indicates a probable infectious cause of the pulmonary disease process.

Administration, Intravesical↗
PubMed1982

Control of nitrogenase in a photosynthetic autotrophic bacterium, Ectothiorhodospira sp.

An Ectothiorhodospira species fixed nitrogen when grown as an autotroph in completely inorganic medium by using a variety of electron donors. The organism also used organic carbon sources; however, this required induction of synthesis of various enzymes, whereas the enzymes needed for autotrophic growth were synthesized constitutively. Nitrogenase induction and function were inhibited by ammonium chloride. Nitrogenase activity was dependent on light and inhibited by oxygen.

Aerobiosis↗
PubMedDate not supplied

Evaluation of tympanic membrane thermometer for use with pediatric patients.

To determine if a tympanic membrane thermometer is of benefit on a pediatric unit. Temperature readings using a tympanic membrane thermometer and an electronic thermometer were compared for 295 paired observations. The electronic temperature readings were done by rectal (n = 32), oral (n = 65), and axillary (n = 198) routes. Differences in tympanic and electronic readings were compared by paired t-tests, and the readings were also correlated. The nursing time in seconds was also compared between electronic and tympanic measurements. Parents and nurses rated their opinion of each type of measurement on a 0-5 Likert scale. Nurses rated the patient's response using the same scale. Results indicate that temperature readings differ by an average of .2- .5 degree between tympanic and electronic thermometers. Correlations are statistically significant but of low-to-moderate strength. Parents and nurses did not rate the types of instruments differently. The nurses rated the electronic axillary method as being more acceptable to toddlers. The tympanic membrane measurement took an average of 30-38 seconds less time to take. Tympanic membrane thermometry saves nursing time. Although the correlations were not strong between electronic and tympanic membrane measurements, the tympanic reading was closer to the electronic rectal reading than to axillary or oral readings.

Adolescent↗