Estimating personal exposures from ambient air pollution measures: using meta-analysis to assess measurement error

BACKGROUND

Although ambient concentrations of particulate matter ≤10 μm (PM10) are often used as proxies for total personal exposure, correlation (r) between ambient and personal PM10 concentrations varies. Factors underlying this variation and its effect on health outcome-PM exposure relationships remain poorly understood.

METHODS

We conducted a random-effects meta-analysis to estimate effects of study, participant, and environmental factors on r; used the estimates to impute personal exposure from ambient PM10 concentrations among 4,012 nonsmoking, participants with diabetes in the Women's Health Initiative clinical trial; and then estimated the associations of ambient and imputed personal PM10 concentrations with electrocardiographic measures, such as heart rate variability.

RESULTS

We identified 15 studies (in years 1990-2009) of 342 participants in five countries. The median r was 0.46 (range = 0.13 to 0.72). There was little evidence of funnel plot asymmetry but substantial heterogeneity of r, which increased 0.05 (95% confidence interval = 0.01 to 0.09) per 10 µg/m increase in mean ambient PM10 concentration. Substituting imputed personal exposure for ambient PM10 concentrations shifted mean percent changes in electrocardiographic measures per 10 µg/m increase in exposure away from the null and decreased their precision, for example, -2.0% (-4.6% to 0.7%) versus -7.9% (-15.9% to 0.9%), for the standard deviation of normal-to-normal RR interval duration.

CONCLUSIONS

Analogous distributions and heterogeneity of r in extant meta-analyses of ambient and personal PM2.5 concentrations suggest that observed shifts in mean percent change and decreases in precision may be generalizable across particle size.

Naive T-cells in myelodysplastic syndrome display intrinsic human telomerase reverse transcriptase (hTERT) deficiency

Telomeres are specialized structures providing chromosome integrity during cellular division along with protection against premature senescence and apoptosis. Accelerated telomere attrition in patients with myelodysplastic syndrome (MDS) occurs by an undefined mechanism. Although the MDS clone originates within the myeloid compartment, T-lymphocytes display repertoire contraction and loss of naive T-cells. The replicative lifespan of T-cells is stringently regulated by telomerase activity. In MDS cases, we show that purified CD3+ T-cells have significantly shorter telomere length and reduced proliferative capacity upon stimulation compared with controls. To understand the mechanism, telomerase enzymatic activity and telomerase reverse transcriptase (hTERT), gene expression were compared in MDS cases (n=35) and healthy controls (n=42) within different T-cell compartments. Telomerase activity is greatest in naive T-cells illustrating the importance of telomere repair in homeostatic repertoire regulation. Compared with healthy controls, MDS cases had lower telomerase induction (P<0.0001) that correlated with significantly lower hTERT mRNA (P<0.0001), independent of age and disease stratification. hTERT mRNA deficiency affected naive but not memory T-cells, and telomere erosion in MDS occurred without evidence of an hTERT-promoter mutation, copy number variation or deletion. Telomerase insufficiency may undermine homeostatic control within the hematopoietic compartment and promote a change in the T-cell repertoire in MDS.

Lenalidomide promotes p53 degradation by inhibiting MDM2 auto-ubiquitination in myelodysplastic syndrome with chromosome 5q deletion

Allelic deletion of the RPS14 gene is a key effector of the hypoplastic anemia in patients with myelodysplastic syndrome (MDS) and chromosome 5q deletion (del(5q)). Disruption of ribosome integrity liberates free ribosomal proteins to bind to and trigger degradation of mouse double minute 2 protein (MDM2), with consequent p53 transactivation. Herein we show that p53 is overexpressed in erythroid precursors of primary bone marrow del(5q) MDS specimens accompanied by reduced cellular MDM2. More importantly, we show that lenalidomide (Len) acts to stabilize MDM2, thereby accelerating p53 degradation. Biochemical and molecular analyses showed that Len inhibits the haplodeficient protein phosphatase 2A catalytic domain alpha (PP2Acα) phosphatase resulting in hyperphosphorylation of inhibitory serine-166 and serine-186 residues on MDM2, and displaces binding of RPS14 to suppress MDM2 autoubiquitination whereas PP2Acα overexpression promotes drug resistance. Bone marrow specimens from del(5q) MDS patients resistant to Len overexpressed PP2Acα accompanied by restored accumulation of p53 in erythroid precursors. Our findings indicate that Len restores MDM2 functionality in the 5q- syndrome to overcome p53 activation in response to nucleolar stress, and therefore may warrant investigation in other disorders of ribosomal biogenesis.

Adolescents' hero identification and self-perception

This study explored associations for having a hero with aspects of adolescents' self-concept for 168 high school students who completed Harter's Self-per ception Profile and questions about their heroes. Having a hero was related to having a stronger sense of social acceptance, romantic appeal, and athletic competence and a weaker sense of scholastic competence.

Inhibition of antigen-induced eosinophilia and late phase airway hyperresponsiveness by an IL-5 antisense oligonucleotide in mouse models of asthma

Chronic airway eosinophilia is associated with allergic asthma and is mediated in part by secretion of IL-5 from allergen-specific Th2 lymphocytes. IL-5 is a known maturation and antiapoptotic factor for eosinophils and stimulates release of nascent eosinophils from bone marrow into the peripheral circulation. An antisense oligonucleotide found to specifically inhibit IL-5 expression in vitro was observed to significantly reduce experimentally induced eosinophilia in vivo, in both the murine OVA lung challenge and allergic peritonitis models. Intravenous administration resulted in sequence-dependent inhibition of eosinophilia coincident with reduction of IL-5 protein levels, supporting an antisense mechanism of action. Potent suppression of lung eosinophilia was observed up to 17 days after cessation of oligonucleotide dosing, indicating achievement of prolonged protection with this strategy. Furthermore, sequence-specific, antisense oligonucleotide-mediated inhibition of Ag-mediated late phase airway hyperresponsiveness was also observed. These data underscore the potential utility of an antisense approach targeting IL-5 for the treatment of asthma and eosinophilic diseases.

The development of circadian rhythms in a human infant

STUDY OBJECTIVES

This study examines the ontogeny and interaction of circadian rhythms of sleep, wake, temperature, melatonin, and feeding in the human newborn, and the influence of photic and non-photic factors on the initiation of entrainment.

DESIGN

An infant's sleep-wake state, temperature, and salivary melatonin were monitored from birth to 6 months. Temperature was obtained every hour, and the infant's sleep/eating onset/termination were observed continuously and recorded until day 182. Salivary melatonin was obtained weekly for a 24-hour period, starting at week 3.

SETTING

The infant slept in his parents' bedroom. All household members awakened, retired, and ate meals according to a fixed schedule during the study, while the infant ate, slept, and woke on demand.

PARTICIPANTS

A healthy male infant was the subject. Biological parents gathered data continuously for six months.

INTERVENTIONS

The infant's schedule was on-demand; the household's was fixed. Illumination was restricted to sunlight.

MEASUREMENTS AND RESULTS

The circadian rhythm of temperature appeared first, soon after birth, and became statistically significant within one week. The wake circadian rhythm appeared second, attaining significance at day 45; approximately the same time that increased melatonin concentration began to occur at sunset. The sleep circadian rhythm appeared last, attaining significance after day 56. Ninety to 120 minute zones of sustained wakefulness first appeared in the second month of life subsequent to awakening and prior to sleep onset. The infant's nocturnal sleep-onset was coupled to sunset before day 60 and subsequently to family bedtime, giving evidence of initial photic entrainment followed by social entrainment.

CONCLUSIONS

Circadian rhythms appeared much more rapidly in this infant than previously reported; their rapid appearance was probably facilitated by maximal exposure to sunlight, and regular social cues. These lighting conditions replicate universal infant experience prior to the invention of artificial light.

Characterization and modulation of immune stimulation by modified oligonucleotides

Single-stranded oligodeoxynucleotides (ODNs) were tested for their ability to stimulate NK cells isolated from murine spleens to lyse target cells. Various sequences were evaluated, some of which have been shown previously to exhibit pharmacologic activity in murine model systems. It was confirmed that the CpG motif was stimulatory only in specific sequence contexts, and we found that phosphorothioate backbones were, in general, less stimulatory than phosphodiester backbones. In addition, this stimulation could be reduced by methylating the cytosine of the CpG and eliminated by modifying all of the cytosines contained in an ODN with methyl, bromo, or iodo modifications to the 5 position of the cytosine ring. These results were compared with the ability of a subset of these ODN sequences to stimulate B cell proliferation in vitro. In this comparison, phosphorothioate backbones were found to be required, and the context of the CpG motif was found to be less critical for activation. Finally, one of the most potent ODNs was shown to activate NK and B lymphocytes when administered in vivo.

Selective inhibition of A-Raf and C-Raf mRNA expression by antisense oligodeoxynucleotides in rat vascular smooth muscle cells: role of A-Raf and C-Raf in serum-induced proliferation

Raf kinases, cytoplasmic serine/threonine protein kinases, have been proposed as important participants in mitogen-induced signal transduction. However, the precise role that Raf kinase isozymes play in cellular responses such as proliferation has not been resolved. The present study investigates the ability of antisense phosphorothioate oligodeoxynucleotides (ODNs), targeted against rat C-Raf and A-Raf kinases, to reduce gene expression and proliferation of cultured rat A10 smooth muscle cells (SMCs). Exposure of A10 cells to ISIS 11061, an active C-Raf antisense ODN, resulted in a potent, dose-dependent inhibition (IC50 = 55 nM) of C-Raf mRNA and protein expression. This inhibition was completely dependent on ODN sequence because the incorporation of increasing numbers of mismatches (up to six) into the sequence resulted in sequential loss of potency. Similarly, a dose-dependent reduction (IC50 = 125 nM) in A-Raf gene expression was observed after treatment of cells with the active A-Raf ODN, ISIS 9069, whereas two scrambled controls were without effect. These results demonstrate that ISIS 11061 and ISIS 9069 reduced gene expression in a sequence-specific and isozyme-specific manner. Moreover, administration of ISIS 11061 and ISIS 9069 to rat SMCs resulted in a significant and potent diminution of serum-induced proliferation with corresponding IC50 values of 216 and 273 nM, respectively. Taken together, these results indicate that A-Raf and C-Raf kinases play an important role in regulating vascular SMC proliferation and that antisense-mediated inhibition of Raf kinase activity may serve as a therapeutic modality in the treatment of vascular proliferative disorders.

Specific binding of leukemia oncogene fusion protein peptides to HLA class I molecules

Many human leukemias are characterized by chromosomal translocations yielding hybrid RNAs capable of encoding fusion chimeric proteins. The unique amino acid sequences found in these oncogenic fusion proteins represent true tumor-specific antigens that are potentially immunogenic. Although these leukemia-specific fusion proteins have an intracellular location, they might be recognized immunologically by T lymphocytes if peptides derived from the unique sequences are capable of presentation by the major histocompatibility complex (MHC) molecules on leukemic cells. The ability of a series of synthetic peptides corresponding to the junctional sequences of chronic myelogenous leukemia (CML)-derived bcr-abl and acute promyelocytic leukemia (APL)-derived PML-RAR alpha fusion proteins to bind to purified class I molecules was studied. A series of 152 peptides 8, 9, 10, and 11 amino acids in length, spanning the b3a2 and b2a2 breakpoints for CML and PML-RAR alpha A and B breakpoints for APL were analyzed for HLA A1, A2.1, A3.2, A11, A24, B7, B8, and B27 binding motifs. Twenty-one CML peptides and 4 APL peptides were predicted to be potential HLA class I binders. The peptides were tested for binding to appropriate purified HLA molecules in a competition radioimmunoassay. Four peptides derived from b3a2 CML breakpoint bound with high (< 50 nmol/L) or intermediate (< or = 500 nmol/L) affinity to HLA A3, A11, and B8. None of the CML b2a2 or PML-RAR alpha A or B junctional peptides showed affinity of this magnitude for the HLA class I molecules tested. This is the first evidence that tumor-specific breakpoint peptides can bind human MHC class I molecules and provides a rationale for developing a therapeutic vaccine strategy.

Genetically engineered deglycosylation of the variable domain increases the affinity of an anti-CD33 monoclonal antibody

M195 is a murine monoclonal antibody that binds to the CD33 antigen and is being tested for the treatment of myeloid leukemia. Surprisingly, a complementarity determining region (CDR)-grafted, humanized M195 antibody displayed a several-fold higher binding affinity for the CD33 antigen than the original murine antibody. Here we show that the increase in binding affinity resulted from eliminating an N-linked glycosylation site at residue 73 in the heavy chain variable region in the course of humanization. Re-introducing the glycosylation site in the humanized antibody reduces its binding affinity to that of the murine antibody, while removing the glycosylation site from the murine M195 variable domain increases its affinity. The removal of variable region carbohydrates may provide a method for increasing the affinity of certain monoclonal antibodies with diagnostic and therapeutic potential.

Current status of the neuromaturational examination as an index of learning disability

To further define the role of the neuromaturational examination in determining the presence of learning problems, we examined 104 boys, ages 9.5 to 14.1 years, representing three populations of school children: normal (32 boys), gifted (37), and learning disabled (35). Information concerning each child's behavior and development was obtained through a parent questionnaire; cognitive ability and academic achievement were measured by the Wechsler Intelligence Scales for Children (revised) and Woodcock -Johnson Psychoeducational Battery, respectively. Significant relationships emerged between the number of neuromaturational signs and data group membership (LD greater than N greater than G,P less than 0.05). The number of neuromaturational signs decreased with age for normal (P less than 0.05) and gifted (P less than 0.05) children, but not for the learning-disabled group. Tasks that differentiated the normal and learning disabled were entered into a stepwise discriminant analysis, with a resulting classification accuracy of 93.1% and 100% for the normal and learning-disabled boys, respectively. Analysis of covariance indicated that differences in performance of the three groups may reflect IQ differences among the populations. Learning disabled boys were more likely to exhibit synkinesis than normal boys, but gifted boys did not differ from the learning disabled in the frequency of synkinesis. Our data indicate that, although a composite set of neuromaturational tasks can discriminate normal and learning-disabled boys with a high level of accuracy, caution is urged because the findings may be more related to overall intelligence than to a specific learning disability.