Just-In-Time Neonatal Endotracheal Intubation Simulation Training: A Randomized Controlled Trial

OBJECTIVE

To assess if simulation-based just-in-time training (JITT, short video and simulation) is superior to video training (5-minute video) in acquiring skill in neonatal endotracheal intubation (ETI).

STUDY DESIGN

A Canadian multicenter randomized trial recruited junior residents who performed neonatal ETI from July 2017 to June 2021. The primary outcomes were overall and first attempt ETI success rate. Secondary outcomes included number of attempts, duration of attempts, ETI-related complications, and residents' confidence level. Statistical analysis included generalized estimating equations, mixed model analysis, Mann-Whitney test, and χ² tests.

RESULTS

Sixty-five residents performed 139 ETI. The overall success rate was similar for both groups (67% vs 70%, P = .71). However, the first attempt success rate was higher for the simulation-based JITT group (54% vs 41%, P = .035). The mean duration of attempts was shorter (35 [SD, 9] vs 62 [SD, 9] seconds, P = .048) and the median number of attempts had a tendency to be lower for the simulation-based JITT group (1 [IQR, 1; 1] vs 1 [IQR, 1; 2], P = .02). There were more mucosal trauma events in the simulation-based JITT group (P = .02). Residents in both groups reported similar confidence level in performing ETI.

CONCLUSIONS

Compared with video training, simulation-based JITT for neonatal ETI did not improve overall success rate. However, simulation-based JITT improved first attempt success rate and decreased the number and the duration of ETI attempts. With its positive clinical impact, simulation-based JITT can become an educational adjunct to neonatal ETI training for residents.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT02809924.

Neurodevelopmental outcomes of preterm infants conceived by assisted reproductive technology

BACKGROUND

There have been concerns about the development of children conceived through assisted reproductive technology. Despite multiple studies investigating the outcomes of assisted conception, data focusing specifically on the neurodevelopmental outcomes of infants conceived through assisted reproductive technology and born preterm are limited.

OBJECTIVE

This study aimed to evaluate and compare the neurodevelopmental outcomes of preterm infants born at <29 weeks' gestation at 18 to 24 months' corrected age who were conceived through assisted reproductive technology and those who were conceived naturally.

STUDY DESIGN

This retrospective cohort study included inborn, nonanomalous infants, born at <29 weeks' gestation between January 1, 2010, and December 31, 2016, who had a neurodevelopmental assessment at 18 to 24 months' corrected age at any of the 10 Canadian Neonatal Follow-Up Network clinics. The primary outcome was neurodevelopmental impairment at 18 to 24 months, defined as the presence of any of the following: cerebral palsy; Bayley-III cognitive, motor, or language composite score of <85; sensorineural or mixed hearing loss; and unilateral or bilateral visual impairment. Secondary outcomes included mortality, composite of mortality or neurodevelopmental impairment, significant neurodevelopmental impairment, and each component of the primary outcome. We compared outcomes between infants conceived through assisted reproductive technology and those conceived naturally, using bivariate and multivariable analyses after adjustment.

RESULTS

Of the 4863 eligible neonates, 651 (13.4%) were conceived using assisted reproductive technology. Maternal age; education level; and rates of diabetes mellitus, receipt of antenatal corticosteroids, and cesarean delivery were higher in the assisted reproduction group than the natural conception group. Neonatal morbidity and death rates were similar except for intraventricular hemorrhage, which was lower in the assisted reproduction group (33% [181 of 546] vs 39% [1284 of 3318]; P=.01). Of the 4176 surviving infants, 3386 (81%) had a follow-up outcome at 18 to 24 months' corrected age. Multivariable logistic regression adjusting for gestational age, antenatal steroids, sex, small for gestational age, multiple gestations, mode of delivery, maternal age, maternal education, pregnancy-induced hypertension, maternal diabetes mellitus, and smoking showed that infants conceived through assisted reproduction was associated with lower odds of neurodevelopmental impairment (adjusted odds ratio, 0.67; 95% confidence interval, 0.52-0.86) and the composite of death or neurodevelopmental impairment (adjusted odds ratio, 0.67; 95% confidence interval, 0.54-0.84). Conception through assisted reproductive technology was associated with decreased odds of a Bayley-III composite cognitive score of <85 (adjusted odds ratio, 0.68; 95% confidence interval, 0.48-0.99) and composite language score of <85 (adjusted odds ratio, 0.67; 95% confidence interval, 0.50-0.88).

CONCLUSION

Compared with natural conception, assisted conception was associated with lower odds of adverse neurodevelopmental outcomes, especially cognitive and language outcomes, at 18 to 24 months' corrected age among preterm infants born at <29 weeks' gestation. Long-term follow-up studies are required to assess the risks of learning disabilities and development of complex visual-spatial and processing skills in these children as they reach school age.

Association of Resident Duty Hour Restrictions, Level of Trainee, and Number of Available Residents with Mortality in the Neonatal Intensive Care Unit

OBJECTIVE

This article assesses the effect of reducing consecutive hours worked by residents from 24 to 16 hours on yearly total hours worked per resident in the neonatal intensive care unit (NICU) and evaluates the association of resident duty hour reform, level of trainee, and the number of residents present at admission with mortality in the NICU.

STUDY DESIGN

This is a 6-year retrospective cohort study including all pediatric residents working in a Level 3 NICU (N = 185) and infants admitted to the NICU (N = 8,159). Adjusted odds ratios (aOR) were estimated for mortality with respect to Epoch (2008-2011 [24-hour shifts] versus 2011-2014 [16-hour shifts]), level of trainee, and the number of residents present at admission.

RESULTS

The reduction in maximum consecutive hours worked was associated with a significant reduction of the median yearly total hours worked per resident in the NICU (381 hour vs. 276 hour, p < 0.01). Early mortality rate was 1.2% (50/4,107) before the resident duty hour reform and 0.8% (33/4,052) after the reform (aOR, 0.57; 95% confidence interval [CI], 0.33-0.98). Neither level of trainee (aOR, 1.22; 95% CI, 0.71-2.10; junior vs. senior) nor the number of residents present at admission (aOR, 2.08; 95% CI, 0.43-10.02, 5-8 residents vs. 0-2 residents) were associated with early mortality. Resident duty hour reform was not associated with hospital mortality (aOR, 0.73; 95% CI, 0.50-1.07; after vs. before resident duty hour reform).

CONCLUSION

Resident duty hour restrictions were associated with a reduction in the number of yearly hours worked by residents in the NICU as well as a significant decrease in adjusted odds of early mortality but not of hospital mortality in admitted neonates.

Severe Neurodevelopmental Impairment in Neonates Born Preterm: Impact of Varying Definitions in a Canadian Cohort

OBJECTIVE

To assess the impact of variations in the definition of severe neurodevelopmental impairment (NDI) on the incidence of severe NDI and the association with risk factors using the Canadian Neonatal Follow-Up Network cohort.

STUDY DESIGN

Literature review of severe NDI definitions and application of these definitions were performed in this database cohort study. Infants born at 23-28 completed weeks of gestation between 2009 and 2011 (n = 2187) admitted to a Canadian Neonatal Network neonatal intensive care unit and assessed at 21 months' corrected age were included. The incidence of severe NDI, aORs, and 95% CIs were calculated to express the relationship between risk factors and severe NDI using the definitions with the highest and the lowest incidence rates of severe NDI.

RESULTS

The incidence of severe NDI ranged from 3.5% to 14.9% (highest vs lowest rate ratio 4.29; 95% CI 3.37-5.47). The associations between risk factors and severe NDI varied depending on the definition used. Maternal ethnicity, employment status, antenatal corticosteroid treatment, and gestational age were not associated consistently with severe NDI. Although maternal substance use, sex, score of neonatal acute physiology >20, late-onset sepsis, bronchopulmonary dysplasia, and brain injury were consistently associated with severe NDI irrespective of definition, the strength of the associations varied.

CONCLUSIONS

The definition of severe NDI significantly influences the incidence and the associations between risk factors and severe NDI. A standardized definition would facilitate site comparisons and scientific communication.

Neurodevelopmental Outcomes of Infants Born at <29 Weeks of Gestation Admitted to Canadian Neonatal Intensive Care Units Based on Location of Birth

OBJECTIVE

To compare mortality and neurodevelopmental outcomes of outborn and inborn preterm infants born at <29 weeks of gestation admitted to Canadian neonatal intensive care units (NICUs).

STUDY DESIGN

Data were obtained from the Canadian Neonatal Network and Canadian Neonatal Follow-up Network databases for infants born at <29 weeks of gestation admitted to NICUs from April 2009 to September 2011. Rates of death, severe neurodevelopmental impairment (NDI), and overall NDI were compared between outborn and inborn infants at 18-21 months of age, corrected for prematurity.

RESULTS

Of 2951 eligible infants, 473 (16%) were outborn. Mean birth weight (940 ± 278 g vs 897 + 237 g), rates of treatment with antenatal steroids (53.9% vs 92.9%), birth weight small for gestational age (5.3% vs 9.4%), and maternal college education (43.7% vs 53.9%) differed between outborn and inborn infants, respectively (all P values <.01). The median Score for Neonatal Acute Physiology-II (P = .01) and Apgar score at 5 minutes (P < .01) were higher in inborn infants. Severe brain injury was more common among outborn infants (25.3% vs 14.7%, P < .01). Outborn infants had higher odds of death or severe NDI (aOR 1.7, 95% CI 1.3-2.2), death or overall NDI (aOR 1.6, 95% CI 1.2-2.2), death (aOR 2.1, 95% CI 1.5-3.0), and cerebral palsy (aOR 1.9, 95% CI 1.1-3.3).

CONCLUSIONS

The composite outcomes of death or neurodevelopmental impairment were significantly higher in outborn compared with inborn infants admitted to Canadian NICUs. Adverse outcomes were mainly attributed to increased mortality and cerebral palsy in outborn neonates.

The impact of sea ice conditions on breeding decisions is modulated by body condition in an arctic partial capital breeder

Determining how environmental conditions interact with individual intrinsic properties is important for unravelling the underlying mechanisms that drive variation in reproductive decisions among migratory species. We investigated the influence of sea ice conditions and body condition at arrival on the breeding propensity, i.e. the decision to reproduce or not within a single breeding season, and timing of laying in migrating common eiders (Somateria mollissima) breeding in the Arctic. Using Radarsat satellite images acquired from 2002 to 2013, we estimated the proportion of open water in the intertidal zone in early summer to track the availability of potential foraging areas for pre-breeding females. Timing of ice-breakup varied by up to 20 days across years and showed strong relationship with both breeding propensity and the timing of laying of eiders: fewer pre-breeding individuals were resighted nesting in the colony and laying was also delayed in years with late ice-breakup. Interestingly, the effect of sea ice dynamics on reproduction was modulated by the state of individuals at arrival on the breeding grounds: females arriving in low condition were more affected by a late ice-breakup. Open water accessibility in early summer, a likely proxy of food availability, is thus crucial for reproductive decisions in a (partial) capital breeder. Our predictive capacity in determining how Arctic-breeding seabirds respond to changes in environmental conditions will require incorporating such cross-seasonal cumulative effects.

Efficacy of minimally invasive surfactant therapy in moderate and late preterm infants: A multicentre randomized control trial

BACKGROUND

Minimally invasive surfactant therapy (MIST) is a new strategy to avoid mechanical ventilation (MV) in respiratory distress syndrome. The primary aim of this study was to test MIST as a means of avoiding MV exposure and pneumothorax occurrence in moderate and late preterm infants (32 to 36 weeks' gestational age).

METHODS

This was a randomized controlled trial including three Canadian centres. Patients were randomized to standard management or to the intervention if they required nasal continuous positive airway pressure of 6 cm H2O and 35% FiO2 in the first 24 hours of life. Patients from the intervention group received MIST immediately after inclusion. The primary outcome was either need for MV or development of a pneumothorax requiring a chest tube. To ensure that clinicians were not biased toward delaying intubation in the intervention group, clinical failure criteria were also used as a primary outcome. The primary outcome was analyzed using bivariate and multivariate logistic regressions.

RESULTS

Among 45 randomized patients, 24 were assigned to MIST and 21 to standard management. Eight infants (33%) from the intervention group met the primary outcome criteria versus 19 (90%) in the control group (absolute risk reduction 0.57, 95% confidence interval 0.54 to 0.60). One patient in each group reached the primary outcome because of pneumothorax occurrence. The other patients were exposed to MV. None of the patients reached the clinical failure criteria.

CONCLUSION

MIST for respiratory distress syndrome management in moderate and late preterm infants was associated with a significant reduction of MV exposure and pneumothorax occurrence.

Body Composition in Very Preterm Infants: Role of Neonatal Characteristics and Nutrition in Achieving Growth Similar to Term Infants

BACKGROUND

The identification of factors involved in the postnatal growth of preterm infants will help achieve growth similar to that of term infants.

OBJECTIVES

As per protocol: to compare body composition in very preterm infants at term-corrected age (TCA) with that in term infants, and to explore relationships between neonatal characteristics and body composition in preterm infants.

METHODS

Anthropometry, nutritional characteristics, and neonatal outcomes were prospectively collected in 26 preterm (<29 weeks) and 33 term (37-40 weeks) infants. Body composition using dual-energy X-ray absorptiometry (DXA) was measured at TCA in preterm infants and between days 7 and 10 in term infants.

RESULTS

Parenteral nutrition in preterm infants provided a mean of 2.9 ± 0.2 and 2.1 ± 0.5 g/kg/day of intravenous amino acids and lipids, respectively, during the first week of life. The mean weight gain velocity from birth to DXA assessment was 12.1 ± 1.4 g/kg/day. Compared with term infants, preterm infants at TCA were shorter and lighter, with a smaller head circumference, a lower weight estimated by DXA (2,960 ± 552 vs. 3,843 ± 377 g), and increased skinfold thicknesses. Fat mass percent (13.9 ± 5.4%) and lean mass percent (84.7 ± 5.6%) in preterm infants were similar to those in term infants (14.7 ± 3.5 and 83.5 ± 3.6%, respectively). Neonatal weight gain velocity in preterm infants was positively associated with lean mass (grams).

CONCLUSION

Subcutaneous fat is increased in preterm infants. Higher protein intake in preterm infants might increase weight gain velocity and achieve a lean mass comparable to that of term infants.

Prediction of Late Death or Disability at Age 5 Years Using a Count of 3 Neonatal Morbidities in Very Low Birth Weight Infants

OBJECTIVE

To evaluate bronchopulmonary dysplasia (BPD), serious brain injury, and severe retinopathy of prematurity (ROP) as predictors of poor long-term outcome in very low birth weight infants.

STUDY DESIGN

We examined the associations between counts of the 3 morbidities and long-term outcomes in 1514 of 1791 (85%) infants with birth weights of 500-1250 g who were enrolled in the Caffeine for Apnea of Prematurity trial from October 1999, to October 2004, had complete morbidity data, and were alive at 36 weeks postmenstrual age (PMA). BPD was defined as use of supplemental oxygen at 36 weeks PMA. Serious brain injury on cranial ultrasound included grade 3 and 4 hemorrhage, cystic periventricular leucomalacia, porencephalic cysts, or ventriculomegaly of any cause. Poor long-term outcome was death after 36 weeks PMA or survival to 5 years with 1 or more of the following disabilities: motor impairment, cognitive impairment, behavior problems, poor general health, deafness, and blindness.

RESULTS

BPD, serious brain injury, and severe ROP occurred in 43%, 13%, and 6% of the infants, respectively. Each of the 3 morbidities was similarly and independently correlated with poor 5-year outcome. Rates of death or disability (95% CI) in children with none, any 1, any 2, and all 3 morbidities were 11.2% (9.0%-13.7%), 22.9% (19.6%-26.5%), 43.9% (35.5%-52.6%), and 61.5% (40.6%-79.8%), respectively.

CONCLUSIONS

In very low birth weight infants who survive to 36 weeks PMA, a count of BPD, serious brain injury, and severe ROP predicts the risk of a late death or survival with disability at 5 years.

Incidence of invasive aspergillosis following remission-induction chemotherapy for acute leukemia: a retrospective cohort study in a single Canadian tertiary care centre

BACKGROUND

The decision to use universal primary antimould prophylaxis to prevent invasive aspergillosis in patients with acute leukemia depends on the incidence of infection at individual centres. We determined our institution's incidence of invasive aspergillosis among patients who received remission-induction chemotherapy for acute leukemia to evaluate the potential benefits of primary antimould prophylaxis.

METHODS

We conducted this retrospective cohort study at a Canadian tertiary care centre. From the central pharmacy registries, we retrieved records for all adult patients for whom remission-induction chemotherapy for acute leukemia was prescribed between 2008 and 2010. We retrieved clinical, microbiologic, pathologic and radiologic data from the patients' medical charts. The primary outcome was a diagnosis of probable or proven invasive aspergillosis up to 180 days after resolution of aplasia.

RESULTS

We retrieved records for 123 patients with acute leukemia. Twenty-two of these patients did not receive the prescribed chemotherapy and were excluded from the analysis. Of the 101 patients included, 77 (76.2%) had acute myeloid leukemia. Overall, 136 courses of chemotherapy were administered, with more than 1 course administered to 26 (25.7%) of the 101 patients. In 9 of the patients (8.9%; 95% confidence interval 4.2%-16.2%), invasive aspergillosis was diagnosed (3 proven and 6 probable cases) a median of 19 (range 11-34) days after initiation of chemotherapy. In 7 (78%) of these 9 patients, invasive aspergillosis occurred during the first course of chemotherapy. Three patients died within the first year after diagnosis of invasive aspergillosis.

INTERPRETATION

We found a high incidence (8.9%) of invasive aspergillosis at our centre. This finding triggered the introduction of targeted antimould prophylaxis for patients with acute leukemia who were undergoing remission-induction chemotherapy.

Clostridium difficile infection after adult autologous stem cell transplantation: a multicenter study of epidemiology and risk factors

We sought to describe the epidemiology of Clostridium difficile infection (CDI) among adult recipients of autologous hematopoietic stem cell transplantation (auto-HSCT) within the first year after HSCT in centers with variable epidemiology of hypertoxigenic strains. A multicenter, retrospective nested case-control study was conducted among 873 auto-HSCT recipients at Johns Hopkins Hospital (JHH) and Hôpital Maisonneuve-Rosemont (HMR) between January 2003 and December 2008. Despite center differences in the prevalence of NAP-1 strains during the study period (21% to 43% at JHH versus 80% to 84% in HMR), the 1-year incidence of CDI was similar in the 2 hospitals (6.2% at JHH versus 5.7% at HMR). The median time to infection was 11 days (interquartile range, 1 to 27 days). In case-control analyses, grade ≥2 mucositis (odds ratio [OR], 3.00; P = .02) and receipt of a fourth-generation cephalosporin (OR, 2.76; P = .04) were identified as predictors for CDI. Mucositis was the strongest predictor of risk for CDI in multivariate analysis (adjusted OR, 2.77; P = .03). CDI is a common and early complication of auto-HSCT. Treatment-related gastrointestinal mucosal damage, along with the potentially modifiable risk of antimicrobial exposure, influence the risk for CDI early after auto-HSCT.

Extended-release medications for children and adolescents with attention-deficit hyperactivity disorder

Attention-deficit hyperactivity disorder (ADHD) affects one in 20 Canadian children, and is associated with unfavourable academic and employment records, high rates of injury and substance abuse, poor interpersonal relationships, poor mental health outcomes and poor quality of life. Medications have been shown to be efficacious in treating ADHD symptoms in controlled trials, and are associated with better social and health outcomes in observational studies. Extended-release (XR) medications for ADHD are preferred over short-acting immediate-release medications by many families and their treating physicians. The XR preparations are often unaffordable for affected families who are disproportionally among the lower socioeconomic strata.The objective of the present statement was to critically appraise the evidence for the relative effectiveness of XR versus immediate-release medications, and to make recommendations for their appropriate use in the treatment of ADHD.When medication is indicated, XR preparations should be considered as first-line therapy for ADHD because they are more effective and less likely to be diverted. Future research and cost-benefit analyses should consider both efficacy and effectiveness, and the diversion and misuse potentials of these medications. Industry, insurance companies and government must work together to make these medications accessible to all children and youth with ADHD.

Activity-based proteome profiling of hepatoma cells during hepatitis C virus replication using protease substrate probes

Activity-based protein profiling (ABPP) offers direct insight into changes in catalytic activity of enzyme classes in complex proteomes, rather than protein or transcript abundance. Here, ABPP was performed in Huh7 hepatoma cell lines with a group of ABPP probes composed of an N-acetylated amino acid, that mimic the P(1) position in protease peptide substrates. Five different probes bearing distinct amino acids (Ser, Thr, Phe, Glu and His) labeled 54 differentially active proteins, including proteases, other hydrolases, oxidoreductases and isomerases. Four of the six protease families were targeted based on their P(1) substrate preferences. The broader specificity of the labeling observed could be explained by the substrate-based targeting nature and the electrophilic properties of the ABPP probes. When applied to Huh7 cells stably replicating hepatitis C virus (HCV) subgenomic replicon RNA, four proteins showed reduced activity, while three proteins had increased activity during HCV replication. These differentially active hits included carboxylesterase 1, cathepsin D, HSP105, protein disulfide isomerase 1 and A6, chaperonin containing TCP1 and isochorismatase domain containing 1, which demonstrated substrate preferences by being labeled by specific substrate probes. This illustrates the broader activity-based profiling capabilities of these substrate-based probes to reveal novel enzyme candidates and their potential roles during HCV replication.

Transcriptional profiling of the effects of 25-hydroxycholesterol on human hepatocyte metabolism and the antiviral state it conveys against the hepatitis C virus

Background

Hepatitis C virus (HCV) infection is a global health problem. A number of studies have implicated a direct role of cellular lipid metabolism in the HCV life cycle and inhibitors of the mevalonate pathway have been demonstrated to result in an antiviral state within the host cell. Transcriptome profiling was conducted on Huh-7 human hepatoma cells bearing subgenomic HCV replicons with and without treatment with 25-hydroxycholesterol (25-HC), an inhibitor of the mevalonate pathway that alters lipid metabolism, to assess metabolic determinants of pro- and antiviral states within the host cell. These data were compared with gene expression profiles from HCV-infected chimpanzees.

Results

Transcriptome profiling of Huh-7 cells treated with 25-HC gave 47 downregulated genes, 16 of which are clearly related to the mevalonate pathway. Fewer genes were observed to be upregulated (22) in the presence of 25-HC and 5 genes were uniquely upregulated in the HCV replicon bearing cells. Comparison of these gene expression profiles with data collected during the initial rise in viremia in 4 previously characterized HCV-infected chimpanzees yielded 54 overlapping genes, 4 of which showed interesting differential regulation at the mRNA level in both systems. These genes are PROX1, INSIG-1, NK4, and UBD. The expression of these genes was perturbed with siRNAs and with overexpression vectors in HCV replicon cells, and the effect on HCV replication and translation was assessed. Both PROX1 and NK4 regulated HCV replication in conjunction with an antiviral state induced by 25-hydroxycholesterol.

Conclusion

Treatment of Huh-7 cells bearing HCV replicons with 25-HC leads to the downregulation of many key genes involved in the mevalonate pathway leading to an antiviral state within the host cell. Furthermore, dysregulation of a larger subset of genes not directly related to the mevalonate pathway occurs both in 25-HC-treated HCV replicon harbouring cells as well as during the initial rise in viremia in infected chimpanzees. Functional studies of 3 of these genes demonstrates that they do not directly act as antiviral gene products but that they indirectly contribute to the antiviral state in the host cell. These genes may also represent novel biomarkers for HCV infection, since they demonstrate an outcome-specific expression profile.

Peroxisome proliferator-activated receptor alpha antagonism inhibits hepatitis C virus replication

Hepatitis C virus (HCV) is a global health problem and a leading cause of liver disease. Here, we demonstrate that the replication of HCV replicon RNA in Huh-7 cells is inhibited by a peroxisome proliferator-activated receptor (PPAR) antagonist, 2-chloro-5-nitro-N-(pyridyl)benzamide (BA). Downregulation of PPARgamma with RNA interference approaches had no effect on HCV replication in Huh-7 cells, whereas PPARalpha downregulation inhibited HCV replication. Fluorescence and coherent anti-Stokes Raman scattering (CARS) microscopy demonstrate a clear buildup of lipids upon treatment with BA. These observations are consistent with the misregulation of lipid metabolism, phospholipid secretion, cholesterol catabolism, and triglyceride clearance events associated with the inhibition of PPARalpha. The inhibition of HCV replication by BA may result from disrupting lipidation of host proteins associated with the HCV replication complex or, more generally, by disrupting the membranous web where HCV replicates.

Bcl-2 decreases cell proliferation and promotes accumulation of cells in S phase without affecting the rate of apoptosis in human ovarian carcinoma cells

OBJECTIVES

The Bcl-2 protein is an important regulator of the apoptotic cascade and promotes cell survival. Bcl-2 can also delay entry into the cell cycle from quiescence. In the present study, we used two isogenic human ovarian carcinoma cell lines, which expressed differential levels of Bcl-2 proteins, to demonstrate that Bcl-2 may regulate the growth rates of adenocarcinoma cells.

METHODS

The growth rates of two isogenic ovarian cancer cell lines were determined by XTT assays and flow cytometry combined with PI staining. Bcl-2-overexpressing SKOV3 cells were modified to express a doxycycline-inducible anti-Bcl-2 single-chain antibody and the effects of Bcl-2 protein inhibition on cell proliferation and apoptosis were assessed.

RESULTS

We demonstrate that Bcl-2 promotes the accumulation of proliferating carcinoma cells in S phase. The Bcl-2-overexpressing SKOV3 cell line proliferates markedly faster and shows delayed progression to G2M phase compared to its low Bcl-2-expressing counterpart SKOV3.ip1 cell line. Single-chain antibody-mediated inhibition of Bcl-2 in SKOV3 cells was associated with increased growth rates and more rapid cell cycle progression. Treatment with cisplatin resulted in more cells accumulating in S phase in Bcl-2-overexpressing SKOV3 cells, while the inhibition of Bcl-2 abolished delayed entry into G2M phase without affecting cisplatin-induced apoptosis.

CONCLUSIONS

Our results suggest that, in ovarian cancer cells, Bcl-2 delays cell cycle progression by promoting accumulation of cells in S phase without affecting the rate of apoptosis. Thus, in addition to its known role at the G0/G1 checkpoint, we demonstrate for the first time that Bcl-2 also regulates the S phase.

Fluticasone inhalation in moderate cases of bronchopulmonary dysplasia

OBJECTIVE

This randomized, controlled trial was designed to determine the efficacy of inhaled fluticasone propionate on oxygen therapy weaning in a population of preterm infants who were born at <32 weeks of gestation and experienced moderate bronchopulmonary dysplasia (BPD).

METHODS

Thirty-two infants who were < or =32 weeks of gestation, had moderate BPD that required supplemental oxygen (fraction of inspired oxygen > or =0.25), and were aged between 28 and 60 days were randomized. Fluticasone propionate 125 microg twice daily for 3 weeks and once daily for a fourth week was delivered to infants who weighed between 500 and 1200 g. The dosage was doubled for infants who weighed > or =1200 g.

RESULTS

Compared with placebo, treatment had no effect on either duration of supplemental O2 therapy or ventilatory support as assessed by survival analysis. At 28 days, a trend toward a lower cortisol/creatinine ratio in the treatment group was noted compared with placebo (25.1 +/- 18.9 vs 43 +/- 14.4). In the fluticasone group at 28 days, the systolic arterial pressure (78 +/- 3 vs 68 +/- 3 mm Hg) and diastolic arterial pressure (43 +/- 3.4 mm Hg vs 38 +/- 2.0 mm Hg) were higher compared with baseline fluticasone values. The chest radiograph score was lower than baseline (2.8 +/- 1.4 vs 3.7 +/- 2.2) in the fluticasone group at 28 days. This study has a statistical power of 1.0 to detect a significant difference in the duration of oxygen supplementation of >21 days between the study groups.

CONCLUSION

We conclude that fluticasone propionate reduces neither supplemental O2 use nor the need for ventilatory support in this patient population. However, fluticasone does have a positive radiologic effect in lowering chest radiograph scores. In addition, our data point to a possible association among inhaled fluticasone treatment and higher arterial blood pressure. Thus, the results of this investigation do not support the use of inhaled corticosteroids in the treatment of oxygen-dependent infants who have established moderate BPD.

Beyond the workplace: an exploratory study of the impact of neurotoxic workplace exposure on marital relations

BACKGROUND

The impact on family life and social relations that may result from symptoms associated with exposure to neurotoxic substances has never been addressed. This exploratory study assessed the associations between exposure to neurotoxic agents in the workplace, mental health, and marital difficulties.

METHODS

Fifty-five (55) male workers and their spouses completed standardized measures of mental health and marital difficulties. Workers' exposure to neurotoxic substances was evaluated by questionnaire and interview, using a semiquantitative classification system.

RESULTS

A positive relation was observed between exposure level and measures of workers' psychological symptoms and marital stress; no relation was observed between workers' exposure level and wives' psychological symptoms. More severe exposure to neurotoxic substances was associated with wives' reports of more severe marital conflicts, and this association was mediated by husbands' psychological symptoms. As compared to low exposure husbands, high exposure husbands reported higher degrees of stress surrounding marital discussions, more consistent incidence of minor physical assaults by wives, and stronger associations between their levels of stress, the verbal aggressions of wives, and the number of marital conflicts.

CONCLUSIONS

The results of this study confirm that neurotoxic exposure is a risk factor for mental health and suggest how this may influence marital relations. Because of the importance of these findings for the well-being of workers and their families, these associations should be further studied.

Toxicity profile of interferon alfa-2b in children: A prospective evaluation

The toxicity of interferon (IFN) alfa-2b therapy was prospectively evaluated in 53 children treated from 1991 to 1996 in 2 successive studies of IFN alfa therapy for severe hemangiomas at Sainte-Justine Hospital. Toxicity was generally mild and transient, with grade 1 toxicity occurring in 100% of patients, grade 2 toxicity in 89%, grade 3 toxicity in 58%, and grade 4 toxicity in 17%. Ten of 43 patients available for evaluation had an abnormal neurologic examination. Severe neurotoxicity in the form of spastic diplegia occurred in one patient. In conclusion, IFN alfa therapy is generally well tolerated in children. However, it may rarely be associated with severe toxicity and must be used with caution.

Manganese neurotoxicity, a continuum of dysfunction: results from a community based study

Excessive manganese (Mn) has been associated with neurobehavioral deficits and neurological and/or neuropsychiatric illness, but the level at which this metal can cause adverse neurotoxic effects, particularly with long-term exposure, is still unknown. The objective of the present study was to assess nervous system functions in residents exposed to manganese from a variety of environmental sources. A random stratified sampling procedure was used to select participants; persons with a history of workplace exposure to Mn and other neurotoxic substances were excluded. A self-administered questionnaire provided data on socio-demographic variables. Blood samples were analyzed for total manganese (MnB), lead, mercury and serum iron. Nervous system assessment included computer and hand-administered neurobehavioral tests, computerized neuromotor tests, sensory evaluation and a neurological examination. The present analyses include 273 persons (151 women and 122 men); MnB range: 2.5 micrograms/L-15.9 micrograms/L (median: 7.3 micrograms/L). Multivariate analyses were used and neuro-outcomes were examined with respect to MnB, taking into account potential confounders and covariables. Results were grouped according to neurofunctional areas and MANOVA analyses revealed that higher MnB (7.5 micrograms/L) was significantly associated with changes in coordinated upper limb movements (Wilks' lambda = 0.92; p = 0.04) and poorer learning and recall (men: Wilks' lambda = 0.77; p = 0.002; women: Wilks' lambda = 0.86; p = 0.04). Further analyses revealed that with increasing log MnB (Simple regression: p < 0.05) performance on a pointing task was poorer, frequency dispersion of hand-arm tremor decreased, while harmonic index increased, and the velocity of a pronation/supination arm movement was slower. An Mn-age interaction was observed for certain motor tasks, with the poorest performance observed among those _50 y and in the higher MnB category. Differences between genders suggest that men may be at greater risk than women, although effects were also observed in women. These findings are consistent with the hypothesis that Mn neurotoxicity can be viewed on a continuum of dysfunction, with early, subtle changes at lower exposure levels.

Bioindicator and exposure data for a population based study of manganese

Exposure data and bioindicators were obtained for a study whose objective was detection of early manifestations of manganese (Mn) neurotoxicity in a population with potential environmental exposure. The study included persons with no history of neurotoxic workplace exposure in Southwest Quebec, drawn from seven postal code regions, defining a set of geographically contiguous zones. Blood samples were analyzed for total Mn (MnB), lead (PbB), total mercury (HgT) and serum iron (FeS). Drinking water samples from participants' residences were analyzed for manganese (MnW). At 4 sites, limited 24-hour high volume air samples for total particulates (TP) and PM10, were analyzed for Mn and Pb. Sociodemographic and dietary information was obtained by self-administered questionnaire. The geometric mean (GM) for MnB values (n = 297) was 7.14 micrograms/L. Levels of MnB in women (n = 156; GM 7.50 micrograms/L) were significantly higher than in men (n = 141; GM 6.75 micrograms/L). No relationship was found between MnB and PbB or HgT. FeS was significantly higher in men (GM 18.38 mumol/L) than women (GM 15.0 mumol/L). For women, MnB was correlated to FeS, with a tendency to decrease with increasing age. For men, no relationship was found between MnB levels and either FeS or age, although FeS showed a strong inverse relationship with age. The 24-hour mean levels of MnTP at the 4 sites varied between 0.009 microgram/m3 and 0.035 microgram/m3; intersite differences were not significant. For Mn in PM10 (MnPM10), mean values ranged from 0.007 microgram/m3 to 0.019 microgram/m3; intersite differences were significant. A total of 278 MnW samples were obtained, 16 from residences served by wells. The GM for MnW was 4.11 micrograms/L (range: 0.50-71.1 micrograms/L, excluding wells; MnW for wells ranged from non-detectable to 158.9 micrograms/L. Individually, there was no relation between MnW and MnB. Geographic analysis of the MnB and MnW data by an algorithm grouping contiguous postal code zones, combined with air data, lead to definition of a geographic parameter, distinguishing two regions relative to a former manganese alloy plant, which contributed significantly to MnB. A multiple regression model was developed, explaining 6.7% of the variability in MnB (F = 5.12; p < 0.001); when controlling for gender, geographic region with higher levels of airborne manganese and the frequency of consumption of cereals and leaf vegetables contributed positively to MnB levels, while serum iron was negatively related.

Role of vigabatrin and lamotrigine in treatment of childhood epileptic syndromes

PURPOSE

Vigabatrin (VGB) and lamotrigine (LTG) are two new antiepileptic drugs (AEDs) with different mechanisms of action for treatment of refractory epilepsies. Previous reports have indicated efficacy of both drugs in a number of epileptic syndromes.

METHODS

We compared these new AEDs drugs to determine their respective efficacy against different types of epileptic syndrome and to develop a rational approach to their use. We reviewed the charts of 105 children, with partial and generalized epilepsies.

RESULTS

VGB was to be significantly more effective in children with partial epilepsies, and LTG was more effective in those with generalized epilepsies.

CONCLUSIONS

VGB and LTG have different therapeutic profiles. Combination treatment with the two drugs may represent rational polytherapy for patients with epilepsy resistant to treatment with either drug alone or as add-on to other AED treatment.

Preliminary evidence of neurotoxicity associated with eating fish from the Upper St. Lawrence River Lakes

Pollution of hydrographic basins has affected the flora and fauna that thrive in these aquatic ecosystems, and fish, which constitute an important food resource, often contain a plethora of potentially toxic chemicals. In a major research project on early neurotoxic effects of environmental exposure to manganese among residents in Southwest Quebec, fish consumption from 2 lakes of the Upper St. Lawrence River System, was surveyed as a potential confounding factor. Participants were selected using a random, stratified sampling strategy from lists of the Quebec Health Plan. Following exclusions, 273 men and women between 20-69 years were retained for the present analysis. A total of 103 (37.7%) reported eating fish from the Upper St. Lawrence. Although fisheaters and non-fisheaters were similar for most socio-demographic variables, significantly more fisheaters (65.2%) reported consuming alcoholic beverages as compared to non-fisheaters (42.4%) (Chi Sq. <0.01). To eliminate this possible bias, fisheaters were matched to non-fisheaters for the variables sex, alcohol consumption (never or occasionally vs. regularly), age (+/-5y) and education (+/-2y). A total of 63 matched pairs were thus created. Paired analyses (t-test or Signed Rank) showed that fisheaters had higher levels of blood organic mercury and lead. Analysis of nervous system functions revealed that both groups performed similarly on tests of sensory function, visual memory and recognition, fine motor performance and some motor tests, but fisheaters performed significantly more poorly (p<0.05) on tests requiring cognitive flexibility, word naming, auditory recall, and more complex motor tasks. The profile of deficits is consistent with diminished capacity for information processing. These observations were made within a study that was not specifically designed to examine the effects of fish eating from these two lakes, and the characterization of fish dietary habits has many limitations. Nevertheless, the findings are sufficiently compelling to warrant further studies, since fish from the Upper St. Lawrence Lakes are known to contain multiple neurotoxic substances.

Interleukin-1 expression during hyperoxic lung injury in the mouse

An important component of the pathophysiologic response to hyperoxia (O2) is pulmonary inflammation, although the roles of specific inflammatory mediators during pulmonary O2 toxicity are not completely known. Interleukin-1 (IL-1) is an early inflammatory mediator and is sufficient to elicit many of the responses associated with acute injury. The IL-1 family comprises two bioactive proteins, IL-1alpha and IL-1beta, and their natural antagonist IL-1ra. Here we report studies of IL-1 regulation during hyperoxic lung injury in the adult mouse. When assayed by Northern blot, increases in IL-1beta mRNA were seen after 2 days of hyperoxia. In contrast, IL-1alpha mRNA was barely detectable before 4 days of hyperoxia. To further understand the cellular origin of IL-1beta expression in lungs, in situ hybridization and immunohistochemical analyses were performed. IL-1beta mRNA or protein was not detected in the lungs of unexposed animals. At 3 days, we observed the accumulation of IL-1beta transcripts in pulmonary interstitial macrophages and in a subset of neutrophils, and immunodetectable IL-1beta protein was co-localized in adjacent sections. At 4 days of exposure, IL-1beta transcripts were widespread in lung tissue, but many areas rich in IL-1beta mRNA were devoid of immunodetectable IL-1beta. However, it is not known whether increased synthesis of IL-1beta or the uncoupling of IL-1beta protein and mRNA accumulation has a role in pathophysiology of pulmonary O2 toxicity.

[The search for information. A calculated risk for cancer patients]

Even though their daily life seems to revolve around suffering, death and uncertainty, cancer patients try to cope with their situation and live life as best they can. Sylvie Bélanger, Head Nurse in the home medicine and care unit at the Cité de la Santé de Laval, and Louise Bouchard, full professor in the Nursing faculty of the Université de Montréal, were interested in better understanding cancer patients' search for information. Their qualitative research showed them that people suffering from cancer feel that there are risks involved in seeking information. The authors found that most of the cancer patients they met with wanted to obtain information allowing them to make it through their cancer and chemotherapy experience in as healthy a manner as possible. Yet this type of information seems hard to come by. Nurses must not hesitate to act in their role as information providers and offer cancer patients the facts they need, to help them view their situation more clearly and calmly.

The effects of tracheal occlusion and release on type II pneumocytes in fetal lambs

Fetal tracheal occlusion (TO) has been shown to lead to lung hyperplasia in various animal models, and this procedure has already been carried out in human fetuses with congenital diaphragmatic hernia (CDH). However, the authors previously showed that TO caused a decrease in type II pneumocytes.

PURPOSE

The aim of this study is to examine the effects of TO and release on type II pneumocytes.

METHOD

To was carried out with a Swan Ganz or Fogarty catheter in fetal sheep at 116 to 118 days of gestation. TO was maintained for 2 weeks followed by deflation of the balloon for 1 week before delivery, in group 1; in group 2, TO was maintained for 19 days and released 2 days before delivery. Group 3 consisted of previously reported animals who had TO maintained until birth. Unoperated twins served as controls. All specimens were analyzed using the surfactant protein C (SP-C) mRNA as a specific marker for type II pneumocytes. We used Northern Blot and in situ hybridization techniques to quantify total SP-C and the density of type II cells. Electron microscopy (EM) was also used to evaluate and quantitate type II cells.

RESULTS

TO resulted in significant lung growth in all groups. In situ hybridization and Northern Blot analysis showed that there was a complete recovery of type II cells in group 1 versus controls. Quantitative EM analysis confirmed these findings. In group 2 the number of type II cells was decreased but there was an increase in SP-C content per type II cell versus group 3.

CONCLUSION

Lung growth after TO appears to occur at the expense of type II cell differentiation. This effect is reversible with the release of TO before birth in this animal model.

Deleterious effect of tracheal obstruction on type II pneumocytes in fetal sheep

It was previously shown that tracheal obstruction accelerated fetal lung growth and eventually reversed the pulmonary hypoplasia in experimental diaphragmatic hernia. We have successfully developed a reversible tracheal obstruction technique in fetal sheep using balloon occlusion and showed that 3 wk of obstruction induced significant lung growth of the same magnitude as the tracheal ligation. The purpose of this study was to examine the effects of 1 and 3 wk of tracheal occlusion on the alveolar cell population with specific attention to the type II pneumocytes. We first showed that 1 wk of occlusion induced a significant increase in lung weight and in alveolar surface area. We then used the surfactant protein C (SP-C) mRNA as a specific marker of differentiated type II pneumocytes. Total RNA was isolated from fetal sheep lung with or without tracheal occlusion, and Northern blots were hybridized with a cDNA probe specific for the sheep SP-C. The results show a dramatic decrease in SP-C mRNA expression (8.8-fold, p < 0.01). In situ hybridization showed a marked decrease in the density of cells expressing SP-C, as well as the amount of SP-C mRNA expressed by the cells. The effect was present as early as 1 wk of occlusion. The sparseness of type II pneumocytes was further confirmed by electron microscopy. We thus conclude that tracheal obstruction causes a profound decrease in the number of type II pneumocytes in the lungs. Given the crucial role of type II pneumocytes in surfactant production, we could speculate that, if tracheal occlusion is able to accelerate lung growth, the final product is probably surfactant-deficient.

Admixture of a multivitamin preparation to parenteral nutrition: the major contributor to in vitro generation of peroxides

BACKGROUND

Peroxides have been reported to contaminate lipid emulsions and amino acid solutions used in total parenteral nutrition (TPN). This is particularly disturbing in newborn infants who are prone to several diseases related to immature defense mechanisms against oxidative challenges. It is not clear whether the antioxidants in multivitamins help protect parenteral nutrients against the hazards of oxidation.

OBJECTIVE

To evaluate the role of a multivitamin preparation (MVI) on the actual peroxide load received by patients on TPN.

METHODOLOGY

The generation of peroxides in parenteral nutrition was tested first using test solutions. We compared the relative contribution of commercially available amino acid solutions, a lipid emulsion, and MVI on the level of peroxides in clinically relevant TPN solutions. Second, we measured the level of peroxides actually infused at the bedside. In both circumstances, the effects of time and light exposure were isolated. The level of peroxides was determined by a colorimetric technique and expressed as microM equivalents tert-butyl hydroperoxide (microM = TBH).

RESULTS

Even when protected from light, the addition of MVI produced a 10-fold increase in peroxides (mean +/- SEM, n = 3, 19 +/- 4 to 189 +/- 8 microM = TBH at 4 h) in the fat-free TPN solution and a fourfold increase (64 +/- 6 to 244 +/- 8 microM = TBH at 4 h) in the lipid-containing TPN solution. A dose-response relationship was found between the concentration of MVI and peroxide levels. The effect of light was the strongest in the presence of multivitamins. The amino acid solutions had a relative inhibitory effect on the generation of peroxides by MVI, which varied (from 54 +/- 1% to 72 +/- 1%) all according to the amino acid blend. In parenterally fed premature infants, protecting the intravenous set from light decreased the load of infused peroxides (146 +/- 15 vs 215 +/- 24 microM = TBH).

CONCLUSIONS

The lipid emulsion had a significant but minor additive effect compared with the multivitamin preparation, which was the major contributor to the generation of peroxides. Protection from photooxidation is not sufficient to prevent peroxidation of TPN solutions. Contrary to what one would expect, increasing the concentration of MVI will lead to a greater generation of peroxides, suggesting that the essential antioxidants in MVI do not have antiperoxide properties.

Influence of bilirubin on the antioxidant capacity of plasma in newborn infants

In vitro, bilirubin is a strong antioxidant, but in vivo its capacity to act as a scavenger of toxic oxygen radicals remains poorly documented. The aim of this study was to evaluate of bilirubin had antioxidant properties in jaundiced infants. The antioxidant capacity of neonatal plasma was measured in Trolox equivalents (TEAC, mmol/l) and correlated in vitro with plasma bilirubin concentrations (r2 = 0.99). Plasma TEAC was compared before and after exchange transfusions for neonatal hyperbilirubinemia (250-435 mumol/l). The antioxidant properties of the paired blood samples before and after exchange transfusions (TEAC: 1.67 +/- 0.12 vs. 1.37 +/- 0.09 mmol/l, n = 11) varied in proportion to the serum bilirubin levels. The changes in other antioxidants were not large enough to account for the magnitude of change in antioxidant capacity. Therefore, in vivo, the plasma antioxidant capacity of jaundiced newborn infants is related to the level of bilirubin.

Surveillance of early neurotoxic dysfunction

Surveillance of early neurotoxic alterations was undertaken in 3 reinforced plastics plants, with a view to preventive intervention. Using a longitudinal study design, exposure parameters (environmental styrene in the respiratory zone of each worker and end-shift mandelic acid (MA)) and neurobehavioral performance (Neurobehavioral Core Test Battery and Field Assessment: Sensory Tests), were assessed at time zero (T0); recommendations were made to reduce exposure at jobsites with the highest risk. Reassessment was made two years later (T2). Complete exposure data was available for 118 workers at T0; 75 were still employed at T2; of these, 57 (76%) returned for testing. Those who returned had more seniority (p < 0.001) and higher MA (p < 0.01) and styrene (p < 0.05) levels at T0 than the others. Analyses, performed on the T0-T2 differences, showed improvement in exposure parameters in Plant 3, where lower levels were observed at T2 for styrene (p < 0.05) and MA (p < 0.001). workers in Plant 3 (n = 29) performed better (p < 0.05) at T2 for short term memory, perceptuo-motor speed, motor precision and manual dexterity; they reported more vigor (p < 0.05) and less anger (p = 0.07). This was not the case for the workers from the other plants. Generally, the T0-T2 difference in MA was associated (Spearman's Rho) with differences in color vision (p < 0.001), simple reaction time (mean and standard deviation), digit span forward, tension, fatigue and the number of symptoms (p < 0.05); aiming precision showed a similar tendency (p < 0.10). These findings suggest that group surveillance of early nervous system changes for jobs with exposure to neurotoxins, using a sensitive neurofunctional test battery, may be useful for preventive intervention.

Pilot study of peripheral markers of catecholaminergic systems among workers occupationally exposed to toluene

In a pilot study, serum dopamine beta-hydroxylase (DBH), platelets monoamine oxidase type B (MAO B) activities and basal plasma prolactin (PRL) were measured, among 10 workers occupationally exposed to toluene and 10 control subjects, preceding and immediately following vacation. Six exposed subjects were employed in an adhesive tape making industry and 4 in a paint making industry. Their median basal levels of urinary hippuric acid were 0.44 mmole/mmole creatinine (cr) (range 0.23-1.97) and 0.18 mmole/mmole cr (range 0.15-0.19) respectively, the second to last morning of the work week, preceding vacation. The level of basal urinary hippuric acid among the control group was 0.26 mmole/mmole cr (range 0.03-0.38). The workers from the adhesive tape plant reported a significantly higher number of symptoms experienced frequently (Kruskal, Wallis, p < 0.05). On a group basis, serum DBH was lowest among the workers from the adhesive tape plant, who had the highest levels of basal urinary hippuric acid. In addition, a negative relation was observed between hippuric acid and serum DBH, preceding and following vacation (Rho = -0.46, p = 0.05; Rho = -0.51, p = 0.03). The observed changes in serum DBH activity are consistent with its decrease in human, following long-term exposure to styrene, another aromatic hydrocarbon. The findings of this pilot study, on a limited number of individuals suggest that DBH may be a sensitive peripheral bioindicator. Further studies of larger groups should be done to confirm the decrease in serum DBH activity with toluene exposure and explore whether this alteration is related to the neurotoxic impairments associated with exposure.

Comparison of effects of 95% and 90% oxygen saturations in respiratory distress syndrome

AIMS

To determine if decreasing arterial blood saturation from 95% to 90% could cause vasoconstriction of the pulmonary vasculature and dilatation of a patent ductus arteriosus in preterm newborn infants with respiratory distress syndrome (RDS).

METHODS

Doppler echocardiographic studies were compared at 95% and 90% pulse oxygen saturation (SpO2) in 13 preterm infants aged 61.7 (4.3) hours with RDS and Doppler echocardiographic evidence of tricuspid regurgitation.

RESULTS

The mean (SD)Doppler echocardiographic indices determined at 95% were heart rate (146 (3.60) beats per minute), acceleration time of the velocity wave forms of the pulmonary artery (PAAT) (51.8 (2.5) milliseconds), ratio of PAAT to right ventricular ejection time (ET) (0.26 (0.02)), diameter of the ductus arteriosus (2.6 (0.6) mm), pulmonary blood flow (0.33 (0.03) l/minute) and the left ventricular shortening fraction (SF)(0.4 (0.02)%). The ascending aorta flow velocity wave form was used for the calculation of pulmonary blood flow. The right ventricular to right atrial systolic pressure gradient calculated using the peak velocity of the tricuspid regurgitation jet was 26.7 (7.4) mm Hg.

CONCLUSIONS

A decrease from 95% to 90% SpO2 did not have any effect on the pulmonary circulatory haemodynamics nor the ductus arteriosus.

[Mental health deterioration in workers exposed to styrene]

Emotional instability which might be an early symptom of more severe disorders, is one of the first manifestations of chronic exposure to organic solvents. The present study measures the association between exposure to styrene and mood states of active workers. A total of 128 workers (85% of the total population) from 3 factories where styrene is used, participated on a voluntary basis. They filled out the following self-administered questionnaires: Profile of Mood States (POMS), Psychiatric Symptom Index and Well-being Index. The results indicate a significant relationship between post work-shift urinary mandelic acid (biological indicator of styrene exposure) and the scores obtained on the POMS scales of tension-anxiety (Spearman's rank correlation rho = 0.30; p < 0.01), anger-hostility (rho = 0.29; p < 0.01), fatigue-inertie (rho = 0.34; p < 0.01), and confusion-bewilderment (rho = 0.23; p = 0.04), as well as the Psychological Distress Index (rho = 0.30; p < 0.01). All scores were adjusted for the effects of 4 potentially confounding variables: age, schooling, alcohol and cigarette consumption. These indicators of mood states do not constitute a diagnosis of mental disease but reveal progressive deterioration of well being associated with neurotoxic exposure in the workplace.

Visual dysfunction among styrene-exposed workers

OBJECTIVES

The present study was undertaken to examine the relation between visual functions and occupational exposure to styrene.

METHODS

A total of 128 workers (85% of the total population), from three glass-reinforced plastics plants in Canada, agreed to participate in the study. Environmental and biological measures were made on the day(s) prior to the assessment of near visual acuity (National Optical Visual Chart), chromatic discrimination (Lanthony D-15 desaturated panel), and near contrast sensitivity (Vistech 6000). The analyses were performed on 81 workers with near visual acuity of at least 1 min of arc at 0.5 m.

RESULTS

The subjects were relatively young [29 (SD 8) years], with little seniority [5 (SD 4) years]. Styrene exposure for 8 h ranged from 6 to 937 (first quartile 21 mg.m-3, third quartile 303 mg.m-3), depending on the job site. The end-shift concentrations of urinary mandelic acid ranged from nondetectable to 1.90 mmol.mmol creatinine-1. Significant positive relations were found between the internal and external styrene exposure measurements and color vision loss adjusted for age, alcohol consumption, and seniority in a multiple regression analysis. The multiple regression analysis is also showed that the end-shift concentration of urinary mandelic acid was inversely related to contrast sensitivity at 6 and 12 cycles.degree-1. Logistic multiple regression models indicated that the end-shift concentration of urinary mandelic acid was related to the prevalences of blurred vision, tearing, and eye irritation.

CONCLUSIONS

These findings suggest that there is a positive relation between styrene exposure and early color and contrast vision dysfunction.

On the role of extraretinal signals for saccade generation

We investigated the accuracy of sequential saccadic eye movements, executed without visual feed-back. We found evidence that the final error of one saccade is corrected during the next, which supports the existence of extraretinal inputs to the saccadic generator. The corrections, however, were incomplete, which suggests that extraretinal signals are only partially effective.

Influence of energy substrates on respiratory gas exchange during conventional mechanical ventilation of preterm infants

OBJECTIVE

The purpose of this study was to determine the optimal parenteral feeding regimen for infants with compromised respiratory function.

METHODS

We studied the influence of varying the source of energy on respiratory gas exchange in 10 infants who were supported by mechanical ventilation and who received intravenous feedings. Two isoenergetic parenteral regimens were infused consecutively; the level of fat intake was varied inversely with that of glucose. Under similar ventilator settings, transcutaneous partial pressures of oxygen and carbon dioxide, as well as indirect calorimetry were measured during each regimen.

RESULTS

Despite the higher carbon dioxide production during the glucose-rich regimen (8.9 +/- 0.7 vs 7.9 +/- 0.4 ml/kg per minute, p < 0.05 by analysis of variance), transcutaneous partial pressure of carbon dioxide remained unaffected, suggesting ventilatory compensation as documented by the increased (p < 0.002) alveolar ventilation. This was not associated with a detectable rise in oxygen consumption, but with a significant change in partial pressure of oxygen (77 +/- 5 vs 66 +/- 3 mm Hg, p < 0.05).

CONCLUSIONS

Ventilator-dependent infants with early and mild bronchopulmonary dysplasia, who receive intravenous feedings of a moderate load of glucose-based energy, can compensate for enhanced carbon dioxide production by increasing their respiratory drive, with a beneficial effect on oxygenation compared with that observed when energy is derived from lipid-based solutions.

Nervous system dysfunction among workers with long-term exposure to manganese

Neurological disorders, bearing many similarities to Parkinson's disease, have been associated with environmental and occupational exposure to manganese (Mn). To document early nervous system dysfunction associated with long-term exposure to Mn, a battery of neurofunctional tests was administered to workers employed in Mn alloy production. Study participation was 95% (n = 115). A matched pair design was used; actively working men, with no history of workplace exposure to neurotoxins, were recruited from the region as referents. Matching was done on the variables: age (+/- 3 years), educational level (+/- 2 years), smoking status, and number of children. Stationary environmental sampling indicated that Mn levels varied widely (geometric means: Mn dust, 0.89 mg/m3; respirable Mn, 0.04 mg/m3). The alloy workers had significantly higher levels of whole blood Mn (geometric mean: 1.03 microgram/100 ml vs 0.68 microgram/100 ml); no differences were observed for urinary Mn. Univariate analysis (paired t test, Signed Rank and McNemar) and multivariate analysis of variance (Hotelling-Lawley statistic) revealed that the pairs differed on symptom reporting, emotional state, motor functions, cognitive flexibility, and olfactory perception threshold; verbal fluency, basic mathematics, reading capability, and attentional capacity were similar. These findings are consistent with current knowledge on brain Mn activity and suggest that manifestations of early manganism can be observed in well designed population studies, using sensitive testing methods.

Parental and patient perceptions about encopresis and its treatment

Treatment of encopresis in childhood is often a long and trying process. Children followed for secondary encopresis in a multidisciplinary clinic between 1984 and 1989 were sent a parent/child mail questionnaire seeking information on their understanding of encopresis as well as their opinions on current treatment modalities. Twenty-eight families responded (20 boys and 8 girls), the child's mean age was 9.8 years, and the mean time elapsed after diagnosis was 3.5 years. Parents and children reported that intestinal dysfunction (53%) and painful defecation (46%) were the most important causes of their encopresis. Treatment modalities including enemas were well accepted by both parents and children, with parents considering dietary changes the most useful treatment modality (p < .01). Children reported that regular "toilet routine" was the most helpful in reestablishing continence. Despite good comprehension of the problem and acceptance of the treatment modalities, the complete recovery rate after 3.5 years was only 35.7%, with no differences noted between responders and nonresponders. Encopresis is a chronic condition that persists in a significant proportion of patients, despite adequate patient and parental knowledge and patient acceptance of treatment.