Associations between classroom CO2 concentrations and student attendance in Washington and Idaho

Student attendance in American public schools is a critical factor in securing limited operational funding. Student and teacher attendance influence academic performance. Limited data exist on indoor air and environmental quality (IEQ) in schools, and how IEQ affects attendance, health, or performance. This study explored the association of student absence with measures of indoor minus outdoor carbon dioxide concentration (dCO(2)). Absence and dCO(2) data were collected from 409 traditional and 25 portable classrooms from 22 schools located in six school districts in the states of Washington and Idaho. Study classrooms had individual heating, ventilation, and air conditioning (HVAC) systems, except two classrooms without mechanical ventilation. Classroom attributes, student attendance and school-level ethnicity, gender, and socioeconomic status (SES) were included in multivariate modeling. Forty-five percent of classrooms studied had short-term indoor CO(2) concentrations above 1000 p.p.m. A 1000 p.p.m. increase in dCO(2) was associated (P < 0.05) with a 0.5-0.9% decrease in annual average daily attendance (ADA), corresponding to a relative 10-20% increase in student absence. Annual ADA was 2% higher (P < 0.0001) in traditional than in portable classrooms.

PRACTICAL IMPLICATIONS

This study provides motivation for larger school studies to investigate associations of student attendance, and occupant health and student performance, with longer term indoor minus outdoor CO(2) concentrations and more accurately measured ventilation rates. If our findings are confirmed, improving classroom ventilation should be considered a practical means of reducing student absence. Adequate or enhanced ventilation may be achieved, for example, with educational training programs for teachers and facilities staff on ventilation system operation and maintenance. Also, technological interventions such as improved automated control systems could provide continuous ventilation during occupied times, regardless of occupant thermal comfort demands.

FKRP gene mutations cause congenital muscular dystrophy, mental retardation, and cerebellar cysts

BACKGROUND

Congenital muscular dystrophies (CMD) are autosomal recessive disorders that present within the first 6 months of life with hypotonia and a dystrophic muscle biopsy. CNS involvement is present in some forms. The fukutin-related protein gene (FKRP) is mutated in a severe form of CMD (MDC1C) and a milder limb girdle dystrophy (LGMD2I). Both forms have secondary deficiencies of laminin alpha2 and alpha-dystroglycan immunostaining. Structural brain involvement has not been observed in patients with FKRP gene mutations.

METHODS

The authors studied two unrelated patients who had a pattern of muscle involvement identical to MDC1C, mental retardation, and cerebellar cysts on cranial MRI. The FKRP gene was analyzed along with the skeletal muscle expression of laminin alpha2 and alpha-dystroglycan.

RESULTS

The muscle biopsy of both patients showed severe dystrophic findings, a reduction in laminin alpha2, and profound depletion of alpha-dystroglycan. Both patients had homozygous FKRP gene mutations not previously reported (C663A [Ser221Arg] and C981A [Pro315Thr]).

CONCLUSIONS

Mutations within the FKRP gene can result in CMD associated with mental retardation and cerebellar cysts. This adds structural brain defects to the already wide spectrum of abnormalities caused by FKRP mutations. The severe depletion of alpha-dystroglycan expression suggests that FKRP is involved in the processing of alpha-dystroglycan.

The quantitative measurement of antimicrobial resistance in Escherichia coli at the meta-population level (meta-population analysis)

AIMS

To define a method that describes antimicrobial resistance of meta-populations of bacteria in both a quantitative and biologically meaningful way.

METHODS AND RESULTS

Using spiral plating and colony counting technology we obtained, from animal faecal samples, the density of Escherichia coli that grow at different concentrations of antibiotic. A mathematical description of this dose-response curve fitted the data well. The parameters of this model have biological meaning and the model allowed subtle differences between meta-populations to be detected.

CONCLUSIONS

This method, termed MPA (meta-population analysis), is practical and provides a useful quantitative description of antimicrobial resistance in a bacterial meta-population.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study shows that resistance can be defined quantitatively. The method may be used in many epidemiological and clinical studies of antimicrobial resistance in animals and humans.

Cleavage stage versus blastocyst stage embryo transfer in assisted conception

BACKGROUND

Despite numerous advances in the field of in vitro fertilisation (IVF), many of the widely applied embryo culture techniques and resulting implantation rates have remained relatively unchanged since the first treatment was performed in the mid 1970's. Recent advances in the understanding of nutrient requirements of embryos, have led to a renaissance of extending their culture from the standard procedure of 2-3 days (early cleavage embryo transfer) to 5-6 days (blastocyst culture). The rationale for blastocyst culture is to improve the synchronicity of uterine and embryonic development and provide a mechanism for self-selection of viable embryos. Numerous reports on the clinical benefits of blastocyst culture have led to the worldwide introduction of this technique, despite a deficiency of conclusive evidence to do so.

OBJECTIVES

Primary: To determine if blastocyst stage embryo transfers (ET's) result in higher success rates, than cleavage stage embryo transfers. Secondary: To assess the overall embryo utilisation rate of both techniques.

SEARCH STRATEGY

Electronic searches of the Cochrane Menstrual Disorders and Subfertility Group specialised register of controlled trials, CCTR, MEDLINE, EMBASE, and Bio extracts were performed to identify relevant randomised controlled trials (RCTs). Attempts were also made to identify trials from the National Research Register, the Clinical Trial Register and the citation lists of review articles and included trials. The first or corresponding author of each included trial was also contacted for additional information.

SELECTION CRITERIA

Trials were included if they were randomised and compared the effectiveness of early cleavage versus blastocyst stage transfers.

DATA COLLECTION AND ANALYSIS

Of the 29 trials that were identified, ten trials met the inclusion criteria and were reviewed. Primary outcomes were rates of; live birth, clinical pregnancy and implantation per woman. Secondary outcomes were rates of; miscarriage, monozygotic twinning, embryo freezing, embryo utilisation, cancellation, multiple pregnancy and high order pregnancy and per cycle data. Quality assessment and data extraction were performed independently by two reviewers. Meta analysis was performed using odds ratios for dichotomous outcomes and weighted mean differences for continuous outcomes.

MAIN RESULTS

There was no significant difference between the two treatment groups in live birth rate, although this was reported by only one quasi-random trial (Peto OR 1.59, 95% CI 0.80, 3.15). There was also no evidence of a difference in pregnancy rate (both overall and subgroups) between the two groups for pregnancy rate per couple randomised (4 RCTs: Peto OR 0.86, 95% CI 0.57, 1.29). There was also no suggestion of an overall difference in implantation rates per embryo's transferred although it was impossible to calculate valid confidence intervals from published data (Day 2/3 17.1% vs Day 5/6 18.9%). The subgroup of sequential media trials suggested higher implantation rate for blastocyst transfer (Day 2/3 22.6% vs Day 5/6 32%). The miscarriage rate was no different between the two groups (1 RCT, Peto OR 1.66, 95% CI 0.41, 6.81). The RCTs reporting embryo freezing showed no difference (Peto OR 1.71, 95% CI 1.00, 2.94), however the two quasi-random trials showed a significant difference in favour of the Day 2/3 group (Peto OR 2.99, 95% CI 1.88, 4.75). Embryo transfer cancellation rates were significantly higher in the Day 5/6 group (5 RCTs: Peto OR 0.57, 95% CI 0.40, 0.83). There was no significant difference in the rate of multiple pregnancies or the rate of high order pregnancies (3 RCTs, Peto OR 0.58, 95% CI 0.30, 1.12)(2 RCTs, Peto OR 7.88, 95% CI 0.49, 126.30 respectively).

REVIEWER'S CONCLUSIONS

Overall this review of the best available evidence based on data from randomised controlled trials, suggests that to date little difference in the major outcome parameters has been demonstrated between early embryo transfer and blastocyst culture. Collectively, the increase in cancellation and the possible decrease in cryopreservation rates suggest that the routine practice of blastocyst culture should be offered to patients with caution. The subgroup of trials employing sequential media, did however demonstrate a substantial improvement in implantation rates and similar pregnancy rates, despite the transfer of less embryos. Whether this trend will culminate in convincing higher live birth rates per woman, has yet to be validated.

Comparative efficacy and safety of remifentanil and fentanyl in 'fast track' coronary artery bypass graft surgery: a randomized, double-blind study

This multi-centre, parallel group, randomized, double-blind study compared the efficacy and safety of high-dose remifentanil administered by continuous infusion with an intermittent bolus fentanyl regimen, when given in combination with propofol for general anaesthesia in 321 patients undergoing elective coronary artery bypass graft surgery. A significantly lower proportion of the patients who received remifentanil had responses to maximal sternal spread (the primary efficacy endpoint) compared with those who received fentanyl (11% vs 52%; P<0.001). More patients who received remifentanil responded to tracheal intubation compared with those who received fentanyl (24% vs 9%; P<0.001). However, fewer patients who received remifentanil responded to sternal skin incision (11% vs 36%; P<0.001) and sternotomy (14% vs 60%; P <0.001). Median time to extubation was longer in the subjects who received remifentanil than for those who received fentanyl (5.1 vs 4.2 h; P=0.006). There were no statistically significant differences between the two groups in the times for transfer from intensive care unit or hospital discharge but time to extubation was significantly longer in the remifentanil group. Overall, the incidence of adverse events was similar but greater in the remifentanil group with respect to shivering (P<0.049) and hypertension (P<0.001). Significantly more drug-related adverse events were reported in the remifentanil group (P=0.016). There were no drug-related adverse cardiac outcomes and no deaths from cardiac causes before hospital discharge in either treatment group.

A dose-ranging study to evaluate the antiretroviral activity and safety of amprenavir alone and in combination with abacavir in HIV-infected adults with limited antiretroviral experience

OBJECTIVE

To evaluate the antiretroviral activity and safety of multiple escalating doses of amprenavir administered alone, and in combination with abacavir in HIV-1-infected adults.

DESIGN

Sixty-two HIV-1-infected subjects were enrolled in a multicentre, open-label, non-randomized, dose-escalating trial.

METHODS

Subjects were assigned to one of six dose groups and received amprenavir 300 mg twice daily, 300 mg three times daily, 900, 1050, or 1,200 mg twice daily for 4 weeks. One dose group received amprenavir 900 mg twice daily in combination with abacavir 300 mg twice daily for 4 weeks. Antiretroviral activity was assessed by measuring changes from baseline in plasma HIV-1 RNA levels and CD4 cell counts. Safety was evaluated by monitoring clinical adverse events and changes in laboratory values. Genotypic and phenotypic analyses were performed using ABI sequencing and the recombinant virus assay, respectively.

RESULTS

At week 4, amprenavir monotherapy (900, 1,050, or 1,200 mg twice daily) resulted in marked decreases in plasma HIV-1 RNA levels (1.3-1.6 log10 copies/ml), and substantial increases in CD4 cell counts in the two dose groups who received 1,050 mg twice daily (118 x 10(6) cells/mm3) or 1,200 mg twice daily (114 x 10(6) cells/mm3). Amprenavir/abacavir resulted in median plasma HIV-1 RNA reductions of 1.8 log10 copies/ml, and median CD4 cell count increases of 138 x 10(6) cells/mm3. Amprenavir was reasonably well tolerated with few treatment-limiting adverse events. No known active site mutations associated with amprenavir resistance were selected in any of the dose groups, and no significant phenotypic resistance to amprenavir developed during 4 weeks of therapy.

CONCLUSIONS

The antiviral effect of amprenavir monotherapy increased with escalating doses, and all amprenavir doses were reasonably well tolerated over 4 weeks of therapy. Amprenavir/abacavir combination therapy elicited a potent antiviral effect. The three highest doses of amprenavir (900, 1,050 and 1,200 mg twice daily) were selected to design subsequent Phase II and III studies that confirmed the safety profile and efficacy of amprenavir in combination regimens and led to the approval of amprenavir in the USA in 1999.

Evidence from the Pacific troposphere for large global sources of oxygenated organic compounds

The presence of oxygenated organic compounds in the troposphere strongly influences key atmospheric processes. Such oxygenated species are, for example, carriers of reactive nitrogen and are easily photolysed, producing free radicals-and so influence the oxidizing capacity and the ozone-forming potential of the atmosphere-and may also contribute significantly to the organic component of aerosols. But knowledge of the distribution and sources of oxygenated organic compounds, especially in the Southern Hemisphere, is limited. Here we characterize the tropospheric composition of oxygenated organic species, using data from a recent airborne survey conducted over the tropical Pacific Ocean (30 degrees N to 30 degrees S). Measurements of a dozen oxygenated chemicals (carbonyls, alcohols, organic nitrates, organic pernitrates and peroxides), along with several C2-C8 hydrocarbons, reveal that abundances of oxygenated species are extremely high, and collectively, oxygenated species are nearly five times more abundant than non-methane hydrocarbons in the Southern Hemisphere. Current atmospheric models are unable to correctly simulate these findings, suggesting that large, diffuse, and hitherto-unknown sources of oxygenated organic compounds must therefore exist. Although the origin of these sources is still unclear, we suggest that oxygenated species could be formed via the oxidation of hydrocarbons in the atmosphere, the photochemical degradation of organic matter in the oceans, and direct emissions from terrestrial vegetation.

Comprehensive analysis of chromosome 1p deletions in neuroblastoma

BACKGROUND

Chromosome 1p deletions are common in advanced neuroblastomas, but the biological and clinical implications of this clonal rearrangement remain controversial. Previous studies of chromosome 1p loss of heterozygosity (LOH) have been limited by analyses of relatively small number of tumors derived from heterogeneously assessed and treated patient populations. Therefore, a strictly representative cohort of 288 Children's Cancer Group neuroblastoma patients treated on the most recent phase III therapeutic trials was identified.

PROCEDURE

Primary tumors from these patients were analyzed for LOH at precisely mapped and highly informative 1p polymorphic loci located from 1p32 to 1p36.3 by multiplex PCR.

RESULTS

Ninety-three primary tumor specimens (32%) had LOH at multiple 1p36 marker loci. All 1p deletions overlapped the previously determined smallest region of overlap (SRO). One tumor had a small terminal deletion completely within 1p36.3, allowing for further refinement of the 1p36 SRO. We found no evidence to support an additional, nonoverlapping region of LOH within 1p32-36. We confirmed the strong correlation of 1p36 LOH with MYCN amplification (P < 0.001), advanced disease stage (P < 0.001), and decreased both 3-year event-free survival and overall survival probabilities (P< 0.001). When stratified for MYCN amplification status or entered into a multivariate analysis, 1p36 LOH remained predictive for decreased event-free survival, but not overall survival probability.

CONCLUSIONS

These data support the hypothesis that inactivation of a tumor suppressor gene within 1p36.3 is associated with an increased risk for disease relapse.