Performance of low-cost monitors to assess household air pollution.

Exposure to household air pollution is a leading cause of morbidity and mortality globally. However, due to the lack of validated low-cost monitors with long-lasting batteries in indoor environments, most epidemiologic studies use self-reported data or short-term household air pollution assessments as proxies of long-term exposure. We evaluated the performance of three low-cost monitors measuring fine particulate matter (PM2.5) and carbon monoxide (CO) in a wood-combustion experiment conducted in one household of Spain for 5 days (including the co-location of 2 units of HAPEX and 3 units of TZOA-R for PM2.5 and 3 units of EL-USB-CO for CO; a total of 40 unit-days). We used Spearman correlation (ρ) and Concordance Correlation Coefficient (CCC) to assess accuracy of low-cost monitors versus equivalent research-grade devices. We also conducted a field study in India for 1 week (including HAPEX in 3 households and EL-USB-CO in 4 households; a total of 49 unit-days). Correlation and agreement at 5-min were moderate-high for one unit of HAPEX (ρ = 0.73 / CCC = 0.59), for one unit of TZOA-R (ρ = 0.89 / CCC = 0.62) and for three units of EL-USB-CO (ρ = 0.82-0.89 / CCC = 0.66-0.91) in Spain, although the failure or malfunction rate among low-cost units was high in both settings (60% of unit-days in Spain and 43% in India). Low-cost monitors tested here are not yet ready to replace more established exposure assessment methods in long-term household air pollution epidemiologic studies. More field validation is needed to assess evolving sensors and monitors with application to health studies.

Seasonality and nitrogen supply modify carbon partitioning in understory vegetation of a boreal coniferous forest.

Given the strong coupling between the carbon (C) and nitrogen (N) cycles, there is substantial interest in understanding how N availability affects C cycling in terrestrial ecosystems, especially in ecosystems limited by N. However, most studies in temperate and boreal forests have focused on the effects of N addition on tree growth. By comparison, less is known about the effects of N availability on the cycling of C in understory vegetation despite some evidence that dwarf shrubs, mosses, and lichens play an important role in the forest C balance. In this study, we used an in situ 13CO2 pulse-labeling technique to examine the short-term dynamics of C partitioning in understory vegetation in three boreal Pinus sylvestris forest stands exposed to different rates of N addition: a low and high N addition that receive annual additions of NH4NO3 of 20 and 100 kg N/ha, respectively, and this is a typo. It should be an unfertilized control. Labeling was conducted at two distinct periods (early vs. late growing season), which provided a seasonal picture of how N addition affects C dynamics in understory vegetation. In contrast to what has been found in trees, there was no obvious trend in belowground C partitioning in ericaceous plants in response to N additions or seasonality. Increasing N addition led to a greater percentage of 13C being incorporated into ericaceous leaves with a high turnover, whereas high rates of N addition strongly reduced the incorporation of 13C into less degradable moss tissues. Addition of N also resulted in a greater percentage of the 13C label being respired back to the atmosphere and an overall reduction in total understory carbon use efficiency. Taken together, our results suggest a faster cycling of C in understory vegetation with increasing N additions; yet the magnitude of this general response was strongly dependent on the amount of N added and varied seasonally. These results provide some of the first in situ C and N partitioning estimates for plants growing under the complex web of resource limitations in the boreal understory.

Exposure to Smoke From Wildfire, Prescribed, and Agricultural Burns Among At-Risk Populations Across Washington, Oregon, and California.

Wildfires, prescribed burns, and agricultural burns all impact ambient air quality across the Western U.S.; however, little is known about how communities across the region are differentially exposed to smoke from each of these fire types. To address this gap, we quantify smoke exposure stemming from wildfire, prescribed, and agricultural burns across Washington, Oregon, and California from 2014 to 2020 using a fire type-specific biomass burning emissions inventory and the GEOS-Chem chemical transport model. We examine fire type-specific PM2.5 concentration by race/ethnicity, socioeconomic status, and in relation to the Center for Disease Control's Social Vulnerability Index. Overall, population-weighted PM2.5 concentrations are greater from wildfires than from prescribed and from agricultural burns. While we found limited evidence of exposure disparities among sub-groups across the full study area, we did observe disproportionately higher exposures to wildfire-specific PM2.5 exposures among Native communities in all three states and, in California, higher agricultural burn-specific PM2.5 exposures among lower socioeconomic groups. We also identified, for all three states, areas of significant spatial clustering of smoke exposures from all fire types and increased social vulnerability. These results provide a first look at the differential contributions of smoke from wildfires, prescribed burns, and agricultural burns to PM2.5 exposures among demographic subgroups, which can be used to inform more tailored exposure reduction strategies across sources.

Alström syndrome is associated with short stature and reduced GH reserve.

INTRODUCTION: Alström syndrome (ALMS) is a rare autosomal recessive monogenic disease included in an emerging class of genetic disorders called 'ciliopathies' and is likely to impact the central nervous system as well as metabolic and endocrine function. Individuals with ALMS present clinical features resembling a growth hormone deficiency (GHD) condition, but thus far no study has specifically investigated this aspect in a large population. MATERIAL AND METHODS: Twenty-three patients with ALMS (age, 1-52 years; 11 males, 12 females) were evaluated for anthropometric parameters (growth charts and standard deviation score (SDS) of height, weight, BMI), GH secretion by growth hormone-releasing hormone + arginine test (GHRH-arg), bone age, and hypothalamic-pituitary magnetic resonance imaging (MRI). A group of 17 healthy subjects served as controls in the GH secretion study. Longitudinal retrospective and prospective data were utilized. RESULTS: The length-for-age measurements from birth to 36 months showed normal growth with most values falling within -0·67 SDS to +1·28 SDS. A progressive decrease in stature-for-age was observed after 10 years of age, with a low final height in almost all ALMS subjects (>16-20 years; mean SDS, -2·22 ± 1·16). The subset of 12 patients with ALMS tested for GHRH-arg showed a significantly shorter stature than age-matched controls (154·7 ± 10·6 cm vs 162·9 ± 4·8 cm, P = 0·009) and a mild increase in BMI (Kg/m(2) ) (27·8 ± 4·8 vs 24·1 ± 2·5, P = 0·007). Peak GH after GHRH-arg was significantly lower in patients with ALMS in comparison with controls (11·9 ± 6·9 µg/l vs 86·1 ± 33·2 µg/l, P < 0·0001). Severe GHD was evident biochemically in 50% of patients with ALMS. The 10 adult ALMS patients with GHD showed a reduced height in comparison with those without GHD (149·7 ± 6·2 cm vs 161·9 ± 9·2 cm, P = 0·04). MRIs of the diencephalic and pituitary regions were normal in 11 of 12 patients. Bone age was advanced in 43% of cases. CONCLUSIONS: Our study shows that 50% of nonobese ALMS patients have an inadequate GH reserve to GHRH-arg and may be functionally GH deficient. The short stature reported in ALMS may be at least partially influenced by impairment of GH secretion.

Sedimentological control on Mn, and other trace elements, in groundwater of the Bengal delta.

To reveal what controls the concentration and distribution of possibly hazardous (Mn, U, Se, Cd, Bi, Pb) and nonhazardous (Fe, V, Mo, PO(4)) trace elements in groundwater of the Bengal delta, we mapped their concentrations in shallow groundwater (<60 mbgl) across 102 km(2) of West Bengal. Only Mn is a potential threat to health, with 55% of well water exceeding 0.3 mg/L, the current Indian limit for drinking water in the absence of an alternate source, and 75% exceeding the desirable limit of 0.1 mg/L. Concentrations of V are <3 µg/L. Concentrations of U, Se, Pb, Ni, Bi, and Cd, are below WHO guideline values. The distributions of Fe, Mn, As, V, Mo, U, PO(4), and δ(18)O in groundwater reflect subsurface sedimentology and sources of water. Areas of less negative δ(18)O reveal recharge by sources of evaporated water. Concentrations of Fe, As, Mo, and PO(4) are high in palaeo-channel groundwaters and low in palaeo-interfluvial groundwaters. Concentrations of U, V, and Mn, are low in palaeo-channel groundwaters and high in palaeo-interfluvial groundwaters. Concentrations of Fe and Mn are highest (18 and 6 mg/L respectively) at dual reduction-fronts that form strip interfaces at depth around the edges of palaeo-interfluvial aquifers. The fronts form as focused recharge carries dissolved organic carbon into the aquifer margins, which comprise brown, iron-oxide bearing, sand. At the Mn-reduction front, concentrations of V and Mo reach peak concentrations of 3 µg/L. At the Fe-reduction front, concentrations of PO(4) and As reach concentrations 3 mg/L and 150 µg/L respectively. Many groundwaters contain >10 mg/L of Cl, showing that they are contaminated by Cl of anthropogenic origin and that organic matter from in situ sanitation may contribute to driving reduction.

Adaptation of continuous-flow cavity ring-down spectroscopy for batch analysis of δ13C of CO2 and comparison with isotope ratio mass spectrometry.

Measurements of δ(13)C in CO(2) have traditionally relied on samples stored in sealed vessels and subsequently analyzed using magnetic sector isotope ratio mass spectrometry (IRMS), an accurate but expensive and high-maintenance analytical method. Recent developments in optical spectroscopy have yielded instruments that can measure δ(13)CO(2) in continuous streams of air with precision and accuracy approaching those of IRMS, but at a fraction of the cost. However, continuous sampling is unsuited for certain applications, creating a need for conversion of these instruments for batch operation. Here, we present a flask (syringe) adaptor that allows the collection and storage of small aliquots (20-30 mL air) for injection into the cavity ring-down spectroscopy (CRDS) instrument. We demonstrate that the adaptor's precision is similar to that of traditional IRMS (standard deviation of 0.3‰ for 385 ppm CO(2) standard gas). In addition, the concentration precision (±0.3% of sample concentration) was higher for CRDS than for IRMS (±7% of sample concentration). Using the adaptor in conjunction with CRDS, we sampled soil chambers and found that soil-respired δ(13)C varied between two different locations in a piñon-juniper woodland. In a second experiment, we found no significant discrimination between the respiration of a small beetle (~5 mm) and its diet. Our work shows that the CRDS system is flexible enough to be used for the analysis of batch samples as well as for continuous sampling. This flexibility broadens the range of applications for which CRDS has the potential to replace magnetic sector IRMS.

Allergen immunotherapy decreases interleukin 4 production in CD4+ T cells from allergic individuals.

Allergen specific CD4+ T cell clones generated from allergic individuals have been shown to produce increased levels of the cytokine interleukin 4 (IL-4), compared to allergen specific clones generated from nonallergic individuals. This difference between CD4+ T cells from allergic and nonallergic individuals with regard to cytokine production in response to allergen is thought to be responsible for the development of allergic disease with increased IgE synthesis in atopic individuals. We examined the production of IL-4 in subjects with allergic rhinitis and in allergic individuals treated with allergen immunotherapy, a treatment which involves the subcutaneous administration of increasing doses of allergen and which is highly effective and beneficial for individuals with severe allergic rhinitis. We demonstrated that the quantity of IL-4 produced by allergen specific memory CD4+ T cells from allergic individuals could be considerably reduced by in vivo treatment with allergen (allergen immunotherapy). Immunotherapy reduced IL-4 production by allergen specific CD4+ T cells to levels observed with T cells from nonallergic subjects, or to levels induced with nonallergic antigens such as tetanus toxoid. In most cases the levels of IL-4 produced were inversely related to the length of time on immunotherapy. These observations indicate that immunotherapy accomplishes its clinical effects by reducing IL-4 synthesis in allergen specific CD4+ T cells. In addition, these observations indicate that the cytokine profiles of memory CD4+ T cells can indeed be altered by in vivo therapies. Thus, the cytokine profiles of memory CD4+ T cells are mutable, and are not fixed as had been suggested by studies of murine CD4+ memory T cells. Finally, treatment of allergic diseases with allergen immunotherapy may be a model for other diseases which may require therapies that alter inappropriate cytokine profiles of memory CD4+ T cells.

Differences defined by bone marrow transplantation suggest that lpr and gld are mutations of genes encoding an interacting pair of molecules.

Homozygosity for either of the lymphoproliferation (lpr) or generalized lymphoproliferative disease (gld) mutations of mice causes the development of systemic lupus erythematosus-like autoimmune syndromes that are characterized by severe lymphadenopathy and highly elevated serum immunoglobulin levels. Although the mutations are nonallelic, analysis of homozygous lpr/lpr and gld/gld mice on the same strain background has indicated that the pathology and severity of the autoimmune syndromes induced by these mutations are indistinguishable. To explain this, it has previously been suggested that lpr and gld may represent mutations in molecules involved in sequential steps of an intracellular metabolic pathway of T cells. We have now investigated the behavior of both lpr and gld in a variety of bone marrow chimeras and have found that functional differences between lpr and gld become apparent after bone marrow transfer. Transfer of lpr/lpr bone marrow to irradiated congenic +/+ recipients caused the development of a graft-vs.-host-like lymphoid wasting syndrome, whereas transfer of gld/gld bone marrow to +/+ recipients resulted in development of a gld-like autoimmune syndrome. Additionally, gld/gld hosts behaved like +/+ hosts irrespective of the genotype of the donor bone marrow, whereas lpr/lpr hosts behaved unlike +/+ hosts when reconstituted with either lpr/lpr, gld/gld, or +/+ bone marrow. These are the first clear differences between these two mutations yet described. Our studies indicate that the molecule altered by the gld mutation is expressed only by bone marrow-derived cells, whereas the molecule altered by the lpr mutation is expressed by both bone marrow-derived cells and by one or more peripheral radioresistant cell populations. To reconcile these differences with the fact that homozygous lpr/lpr and gld/gld mice are indistinguishable, we suggest an alternative model for the relationship between the lpr and gld mutations in which the two molecules affected represent an interacting ligand-receptor pair expressed by different cells.

Two loci affecting B cell responses to B cell maturation factors.

B lymphocytes from DBA/2Ha mice have a genetic defect characterized by a failure to differentiate into antibody-secreting cells in response to a family of lymphokines termed B cell maturation factors (BMFs). By contrast, B cells from DBA/2Ha mice respond normally in PFC assays to the B cell mitogen LPS, and macrophages from these mice are activated by one of the three BMFs. Two loci are responsible for the B cell defect in DBA/2Ha mice. One locus (Bmfr-1) is constitutively expressed throughout life, and maps approximately 13 cM distal to the brown locus on chromosome 4. A second locus (Bmfr-2) becomes active only after sexual maturity and is closely linked to the dilute locus on chromosome 9. At both loci, alleles determining responsiveness to BMFs are dominant over nonresponder alleles. The effect of Bmfr-2 on B cell responsiveness may be related to levels of the steroid sex hormones. DBA/2Ha mice offer a tool for studying the genetic and hormonal regulation of the immune system.

Assimilation of xylem-transported 13C-labelled CO2 in leaves and branches of sycamore (Platanus occidentalis L.).

Previous reports have shown that CO(2) dissolved in xylem sap in tree stems can move upward in the transpiration stream. To determine the fate of this dissolved CO(2), the internal transport of respired CO(2) at high concentration from the bole of the tree was simulated by allowing detached young branches of sycamore (Platanus occidentalis L.) to transpire water enriched with a known quantity of (13)CO(2) in sunlight. Simultaneously, leaf net photosynthesis and CO(2) efflux from woody tissue were measured. Branch and leaf tissues were subsequently analysed for (13)C content to determine the quantity of transported (13)CO(2) label that was fixed. Treatment branches assimilated an average of 35% (SE=2.4) of the (13)CO(2) label taken up in the treatment water. The majority was fixed in the woody tissue of the branches, with smaller amounts fixed in the leaves and petioles. Overall, the fixation of internally transported (13)CO(2) label by woody tissues averaged 6% of the assimilation of CO(2) from the atmosphere by the leaves. Woody tissue assimilation rates calculated from measurements of (13)C differed from rates calculated from measurements of CO(2) efflux in the lower branch but not in the upper branch. The results of this study showed unequivocally that CO(2) transported in xylem sap can be fixed in photosynthetic cells in the leaves and branches of sycamore trees and provided evidence that recycling of xylem-transported CO(2) may be an important means by which trees reduce the carbon cost of respiration.

Frequency and cytokine profile of HPRT mutant T cells in HIV-infected and healthy donors: implications for T cell proliferation in HIV disease.

It has been postulated that HIV-infected patients undergo an active production of virus and CD4+ T cell destruction from the early stages of the disease, and that an extensive postthymic expansion of CD4+ T cells prevents a precipitous decline in CD4+ T cell number. Based on the rebound of the CD4+ T cell number observed in patients undergoing antiretroviral therapy with protease inhibitors, it has been calculated that, on average, 5% of T cells are replaced every day in HIV-infected patients. To obtain an independent estimate of the recycling rate of T cells in the patients, we measured the frequency of cells carrying a loss-of-function mutation at the hypoxanthine guanine phosphoribosyl transferase (hprt) locus. Assuming a recycling rate of 5%/d, an accumulation of 2.6 mutations/10(6)/yr over the physiological accumulation was predicted. Indeed, we observed an elevated frequency of HPRT mutants in the CD4+ T cells of most patients with < 300 CD4+ T cells/mm3 of blood and in the CD8+ T cells of most patients with < 200 CD4+ T cells/mm3, consistent with an elevated and protracted increased division rate in both subsets. However, in earlier stages of the disease the mutant frequency in both CD4+ and CD8+ T cells was lower than in healthy controls. The cytokine production profile of most HPRT mutant CD4+ T cell clones from both healthy and HIV-infected patients was typical of T helper cells type 2 (high IL-4 and IL-10, low IFN-gamma), whereas the cytokine production pattern of wild-type clones was heterogeneous. The cytokine profile of CD8+ clones was indistinguishable between HPRT mutants and wild type. Our data provide evidence of increased CD4+ and CD8+ T cell recycling in the HIV-infected patients.

Human alveolar macrophages present antigen ineffectively due to defective expression of B7 costimulatory cell surface molecules.

Alveolar macrophages, resident phagocytic cells in the lung that derive from peripheral blood monocytes, are paradoxically ineffective in presenting antigen to T cells. We found that antigen presentation by alveolar macrophages could be restored by the addition of anti-CD28 mAb to cultures of T cells and macrophages, indicating that costimulation by alveolar macrophages via the CD28 pathway was defective. In addition, we found that alveolar macrophages activated with IFN-gamma failed to express B7-1 or B7-2 antigens, which normally ligate CD28 on T cells and provide a costimulatory signal required for the activation of T cells. These observations are the first to demonstrate the inability of a "professional" antigen-presenting cell type to effectively express the costimulatory molecules B7-1 and B7-2. Inasmuch as immune reactions within the lung are inevitably associated with inflammatory injury to pulmonary tissue, these observations suggest that reduced expression of B7-1 and B7-2 by alveolar macrophages may be advantageous, as a critical mechanism involved in the induction of peripheral tolerance to the abundance of antigens to which mucosal tissues are continuously exposed.

A multi-species comparison of delta13C from whole wood, extractive-free wood and holocellulose.

The stable carbon (C) isotope composition (delta13C) of tree rings is a powerful metric for reconstructing past physiological responses to climate variation. However, accurate measurement and interpretation are complicated by diagenesis and the translocation of compounds with distinct isotopic signatures. Isolation and analysis of cellulose minimizes these complications by eliminating variation due to biosynthetic pathways; however, isolation of cellulose is time-consuming and has no clear endpoint. A faster and better-defined analytical method is desirable. Our objectives were to determine if there is a direct relationship between the isotopic compositions of whole wood (WW), whole wood treated with solvents to remove mobile extractives (extractive-free wood; EF) and holocellulose (HC) isolated by extractive removal and subsequent bleaching. We also determined if total C concentration could explain the isotopic composition and variation among these three wood components of each sample. A set of wood samples of diverse phylogeny, anatomy and chemical composition, was examined. The mean offset or difference between HC and EF delta13C was 1.07 +/- 0.09 per thousand and the offset between HC and WW was 1.32 +/- 0.10 per thousand. Equivalence tests (with alpha = 0.05) indicated that the relationship between EF delta13C and HC delta13C had a slope significantly similar to 1 +/- 5.5%, whereas for the WW delta13C: HC delta13C relationship, the slope was significantly similar to 1 +/- 10.08%. A regression model using EF delta13C to predict HC delta13C had a slope of 0.97, which was not significantly different from unity (P = 0.264), whereas the regression for WW had a slope of 0.92 which was significantly different from unity (P = 0.0098). Carbon concentration was correlated with HC:WW offset and cellulose:EF offset (P = 0.0501 and 0.007, respectively), but neither relationship explained much of the variation (r2 = 0.12 and 0.14, respectively). We suggest that HC extraction is unnecessary for most analyses of tree-ring delta13C; a simple solvent extraction is a suitable alternative for many applications.

Multiple mechanisms of tumorigenesis in E mu-myc transgenic mice.

Transgenic mice bearing a c-myc oncogene under control of the immunoglobulin heavy chain enhancer (E mu-myc mice) reproducibly develop and die from tumors of the B lymphocyte lineage (J.M. Adams, A.W. Harris, C.A. Pinkert, L.M. Corcoran, W.S. Alexander, S. Cory, R.D. Palmiter, and R.L. Brinster, Nature (Lond.), 318: 533-538, 1985; W.Y. Langdon, A. W. Harris, S. Cory, and J.M. Adams, Cell 47: 11-18, 1986; A.W. Harris, C.A. Pinkert, M. Crawford, W.Y. Langdon, R.L. Brinster, and J.M. Adams, J. Exp. Med., 167: 353-371, 1988; reviewed in S. Cory and J.M. Adams, Annu. Rev. Immunol., 6: 25-48, 1988). Analysis of lymphocytes obtained by serial sampling of peripheral blood from individual hemizygous (E mu-myc/0) and homozygous (E mu-myc/E mu-myc) transgenic mice indicates that proliferation in the original host and transplantability into histocompatible recipients are distinct properties that can be acquired independently and in either order. These two types of transgenic mice differ in that homozygous mice have about one-fourth the life span of hemizygous mice and develop polyclonal, non-transplantable tumors in comparison to the oligoclonal, highly transplantable malignancies seen in hemizygous animals. In conclusion, the overall concept of malignancy is best viewed as an aggregate of the separable parameters of cellular proliferation, clonality, tissue invasiveness, metastasis, and (experimental) transplantability. The E mu-myc transgenic mouse represents an attractive model in which to investigate the multistep nature and alternative pathways of tumorigenesis.

Degeneration and plasticity of the optic pathway in Alström syndrome.

BACKGROUND AND PURPOSE: Alström syndrome is a rare inherited ciliopathy in which early progressive cone-rod dystrophy leads to childhood blindness. We investigated functional and structural changes of the optic pathway in Alström syndrome by using MR imaging to provide insight into the underlying pathogenic mechanisms. MATERIALS AND METHODS: Eleven patients with genetically proved Alström syndrome (mean age, 23 years; range, 6-45 years; 5 females) and 19 age- and sex-matched controls underwent brain MR imaging. The study protocol included conventional sequences, resting-state functional MR imaging, and diffusion tensor imaging. RESULTS: In patients with Alström syndrome, the evaluation of the occipital regions showed the following: 1) diffuse white matter volume decrease while gray matter volume decrease spared the occipital poles (voxel-based morphometry), 2) diffuse fractional anisotropy decrease and radial diffusivity increase while mean and axial diffusivities were normal (tract-based spatial statistics), and 3) reduced connectivity in the medial visual network strikingly sparing the occipital poles (independent component analysis). After we placed seeds in both occipital poles, the seed-based analysis revealed significantly increased connectivity in patients with Alström syndrome toward the left frontal operculum, inferior and middle frontal gyri, and the medial portion of both thalami (left seed) and toward the anterior portion of the left insula (right and left seeds). CONCLUSIONS: The protean occipital brain changes in patients with Alström syndrome likely reflect the coexistence of diffuse primary myelin derangement, anterograde trans-synaptic degeneration, and complex cortical reorganization affecting the anterior and posterior visual cortex to different degrees.

Developmental pharmacodynamics of cyclosporine.

OBJECTIVE: To determine the relationship between human development and in vitro cyclosporine (INN, ciclosporin) pharmacodynamics. METHODS: Fifty-six subjects ranging in age from 3 months to 39 years were studied in this prospective laboratory investigation at a university children's hospital and clinical pharmacology laboratory. Peripheral blood monocytes were separated from whole blood and cultured with phytohemagglutinin A (5 microg/mL) and cyclosporine (0, 6.25, 12.5, 25, 50, 100, 500, 1000, 2500, and 5000 ng/mL). Peripheral blood monocytes cultures were assayed for cell proliferation and supernatant interleukin-2 concentration with use of radionuclide DNA tagging and enzyme-linked immosorbent assay, respectively. After concentration-effect modeling, summary pharmacodynamic parameters, including the maximal drug effect (Emax) and cyclosporine concentration at which 50% of maximal effect (IC50) and 90% of maximal effect (IC90), were determined. These parameters were compared between four consecutive subject age groups: infants (0-1 years), children (>1-4 years), preadolescents (>4-12 years), and adults (>12 years). RESULTS: The peripheral blood monocytes of the infants showed a twofold lower mean IC50 (peripheral blood monocyte proliferation) and sevenfold lower mean IC90 (interleukin-2 expression) than peripheral blood monocytes from older subjects. The three older age groups were similar with respect to mean IC50 and Emax (peripheral blood monocyte proliferation). Lymphocyte subtype proportions measured in peripheral blood monocytes preparations from each age group were generally similar. The experimental conditions (eg, general anesthesia and cyclosporine solvents) did not affect peripheral blood monocytes proliferation, but the highest experimental cyclosporine concentration (ie, 5000 ng/mL) was associated with decreased peripheral blood monocytes viability. CONCLUSIONS: Cyclosporine pharmacodynamics in vitro are related to age. This factor, if neglected, may be a source of iatrogenic risk during pediatric immunosuppressive therapy.

Comparison of convenient indicators of obesity.

A comparative study of obesity measurements was undertaken with 533 male and female subjects, aged 11.8-15.9. Six adiposity measures (three skinfold indices, three height-weight indices) were derived from measures of height, weight, and eight skinfold thickness measurements. A principal components analysis of these adiposity measures resulted in a unifactorial solution accounting for 85.6% of the total variance. A cross-tabulation analysis with the derived factor scores and a criterion visual inspection rating supported the interpretation that the underlying construct of the factor was adiposity, and that a factor score of greater than 1.5 SD above the mean was a suitable standard for labeling obesity. Utilizing this dichotomy of factor scores as a standard, the differential diagnostic capabilities of four adiposity scales commonly used in identifying obesity was undertaken. Pursuit of this methodology, with the use of additional measures and larger sample sizes, is recommended to ensure the validation of an obesity measure.

Morphological changes and photosynthate allocation in ageing Hebeloma crustuliniforme (Bull.) Quel. and Laccaria bicolor (Maire) Orton mycorrhizas of Pinus ponderosa Dougl. ex. Laws.

Seedlings of Pinus Ponderosa Dougl, ex. Laws were grown in root observation containers. They were inoculated with either Hebeloma crustuliniforme (Bull.) Quel. or Laccaria bicolor (Maire) Orton or left uninoculated (control). Oil a monthly basis starting at the eighth month of a 12-month growing period, roots (mycorrhizal root tips from inoculated plants, non-mycorrhizal from control plants) were traced onto acetate sheets. Each root tip was classified as light, 'intermediate' or 'dark' in colour. Roots initiated between months eight and nine were monitored for the next 90 d. All root tips progressed from light-brown to dark-brown to black for all three treatments. Hebeloma crustuliniforme, and to a lesser extent L. bicolor, retarded this progression relative to the control. At the end of 12 months, seedlings were labelled with 14 CO2 to determine the effects of ectomycorrhizal inoculation on carbon supply to roots of the different morphological categories. The amount of 14 C in 'light'L. bicolor and H. crustuliniforme mycorrhizas was 2.3 and 1.8 times greater, respectively, than that in 'light' control root tips. The amount of 14 C in mycorrhizas of the inoculated treatments and, to a lesser extent, roots of the control seedlings decreased as they progressed from 'light' to 'dark'. It is concluded that pondersa pine seedlings continue to allocate photosynthate to morphologically older roots, perhaps to meet maintenance requirements or to supply carbon for growth and metabolism of extra-matrical hyphae. Such allocation may enhance root longevity, which would have an important influence on tree, forest and soil carbon budgets.