Factors influencing posttransplantation employment: does depression have an impact?

BACKGROUND

Depressive disorders are the leading cause of disability in the United States. Liver transplant recipients often have significant psychiatric morbidity, including depression. One of the potential consequences of depression is the inability to work.

OBJECTIVE

The objective of this study was to determine if there is any relationship between depression and posttransplantation employment status in liver transplant recipients.

METHODS

Patients, 18 years of age or older, who had received liver transplants from January 2007 to July 2009 were identified for the retrospective analysis. Individual posttransplantation patient charts were reviewed for patient demographics, transplantation indication, employment history, depression diagnosis, and medications. The pretransplantation charts were used to obtain family psychiatric history, patient psychiatric history, past drug, alcohol, and tobacco use, and pretransplantation employment status.

RESULTS

A total of 91 patients were evaluated, of which 59.3% were males and 40.7% were females, with a mean age of 56 years. In our sample, 23% and 29% of patients were depressed pretransplantation and posttransplantation, respectively. The number of unemployed patients also increased from 10.9%-23.1%. A logistic regression was performed to identify the factors influencing employment posttransplantation, which indicated pretransplantation employment, gender (males more likely to return to work), and depression post transplantation as significant factors with odds rations of 128, 4.1, and 11.5 and corresponding P values of <.0001, .04 and .008, respectively.

CONCLUSION

Posttransplantation depression is significantly associated with post-liver transplantation unemployment. Improved management of depression may facilitate a patient's return to work after transplantation.

Effect of heart rate on hemodynamic endpoints under concomitant microvascular disease in a porcine model

Diagnosis of the ischemic power of epicardial stenosis with concomitant microvascular disease (MVD) is challenging during coronary interventions, especially under variable hemodynamic factors like heart rate (HR). The goal of this study is to assess the influence of variable HR and percent area stenosis (%AS) in the presence of MVD on pressure drop coefficient (CDP; ratio of transstenotic pressure drop to the distal dynamic pressure) and lesion flow coefficient (LFC; ratio of %AS to the CDP at the throat region). We hypothesize that CDP and LFC are independent of HR. %AS and MVD were created using angioplasty balloons and 90-μm microspheres, respectively. Simultaneous measurements of pressure drop (DP) and velocity were done in 11 Yorkshire pigs. Fractional flow reserve (FFR), CDP, and LFC were calculated for the groups HR < 120 and HR > 120 beats/min, %AS < 50 and %AS > 50, and additionally for DP < 14 and DP > 14 mmHg, and analyzed using regression and ANOVA analysis. Regression analysis showed independence between HR and the FFR, CDP, and LFC while it showed dependence between %AS and the FFR, CDP, and LFC. In the ANOVA analysis, for the HR < 120 beats/min and HR > 120 beats/min groups, the values of FFR (0.82 ± 0.02 and 0.82 ± 0.02), CDP (83.15 ± 26.19 and 98.62 ± 26.04), and LFC (0.16 ± 0.03 and 0.15 ± 0.03) were not significantly different (P > 0.05). However, for %AS < 50 and %AS > 50, the FFR (0.89 ± 0.02 and 0.75 ± 0.02), CDP (35.97 ± 25.79.10 and 143.80 ± 25.41), and LFC (0.09 ± 0.03 and 0.22 ± 0.03) were significantly different (P < 0.05). A similar trend was observed between the DP groups. Under MVD conditions, FFR, CDP, and LFC were not significantly influenced by changes in HR, while they can significantly distinguish %AS and DP groups.

Use of (1-3)-beta-d-glucan concentrations in dust as a surrogate method for estimating specific fungal exposures

Indoor exposure to fungi has been associated with respiratory symptoms,often attributed to their cell wall component, (1-3)-beta-D-glucan. Performing(1-3)-beta-D-glucan analysis is less time consuming and labor intensive than cultivation or microscopic counting of fungal spores. This has prompted many to use(1-3)-beta-D-glucan as a surrogate for fungal exposure. The aim of this study was to examine which indoor fungal species are major contributors to the (1-3)-beta-D-glucan concentration in field dust samples. We used the quantitative polymerase chain reaction (QPCR) method to analyze 36 indoor fungal species in 297 indoor dust samples. These samples were also simultaneously analyzed for (1-3)-beta-D-glucan concentration using the endpoint chromogenic Limulus Amebocyte lysate assay. Linear regression analysis, followed by factor analysis and structural equation modeling, were utilized in order to identify fungal species that mostly contribute to the (1-3)-beta-D-glucan concentration in field dust samples. The study revealed that Cladosporium and Aspergillus genera, as well as Epicoccum nigrum, Penicillium brevicompactum and Wallemia sebi were the most important contributors to the (1-3)-beta-D-glucan content of these home dust samples. The species that contributed most to the (1-3)-beta-D-glucan concentration were also the most prevalent in indoor environments. However, Alternaria alternata, a common fungal species in indoor dust, did not seem to be a significant source of (1-3)-beta-D-glucan.

PRACTICAL IMPLICATIONS

This study revealed that the (1-3)-beta-D-glucan content of different fungal species varies widely. (1-3)-beta-D-glucan inhouse dust from the Greater Cincinnati area may be a good marker for some fungal species of the Cladosporium and Aspergillus genera. In contrast, Alternaria alternata did not contribute much to the (1-3)-beta-D-glucan load. Therefore, (1-3)-beta-D-glucan concentration in field samples as a surrogate for total fungal exposure should be used with caution.

Charles River Sprague Dawley rats lack early age-dependent susceptibility to DMBA-induced mammary carcinogenesis

Developmental stages of mammary glands influence their susceptibility to initiating events related to carcinogenesis. The "window of susceptibility" to mammary carcinogenesis is classically defined as the time in early puberty when the mammary gland morphology is most sensitive to initiation events. Administration of the polyaromatic hydrocarbon, 7,12-dimethylbenz(a)anthracene (DMBA), in a single oral dose yields maximal mammary tumor formation when administered in this "window". We examined the DMBA treated mammary glands, precursor lesions, and morphology of the uninvolved mammary epithelium for the first 100 days of life for Charles River Sprague Dawley CD(R) IGS. Our goal was to determine the DMBA dose at which 50% of the rats (IC50) developed carcinoma in situ (CIS) within three months of dosing. Here we demonstrate, rather than the classical U-shaped dose curve in which there is maximum sensitivity for DMBA at 50 days, there is an increasing degree of sensitivity with age in the CD(R) IGS rat. Additionally, we report that vehicle-treated animals developed mammary CIS without any known initiator, and 100 day virgin animals demonstrated lactational changes, independent of DMBA exposure or dose. Lastly, we demonstrate this strain of virgin female rats has elevated pituitary prolactin immunoreactivity independent of the level of mammary differentiation. We conclude this strain of Charles River Sprague Dawley rats has prolactin-induced pituitary stimulation, and therefore, the window of susceptibility for mammary tumorigenesis is absent.

An epidemiological appraisal instrument - a tool for evaluation of epidemiological studies

In recent years, ergonomics practices have increasingly relied upon the knowledge derived from epidemiological studies. In this regard, there is limited research devoted to the exclusive evaluation of the methodological qualities of ergonomics epidemiological studies. The aim of this study was to develop and test a general purpose 'epidemiological appraisal instrument' (EAI) for evaluating the methodological quality of existing or new ergonomic epidemiological studies using a critical appraisal system rooted in epidemiological principles. A pilot EAI version was developed and tested by a team of epidemiologists/physicians/biostatisticians, with the team leader being both epidemiologist and ergonomist. The pilot version was further tested with regard to other raters with/without a background in epidemiology, biostatistics and ergonomics. A revised version was evaluated for criterion validity and reliability. An assessor with a basic background in epidemiology and biostatistics would be able to correctly respond on four out of five questions, provided that subject matter expertise is obtained on specific items. This may improve with the article's quality. Training may have an effect upon assessors with virtually no background in epidemiology/biostatistics, but with a background in ergonomics. In this latter case, the inter-rater degree of agreement is largely above 90% and assessors can resolve their differences in a subsequent round. The EAI proved to be a valid and reliable appraisal instrument that may be used in various applications, such as systematic reviews and meta-analyses.

Histocompatibility testing predicts acute rejection risk in early corticosteroid withdrawal regimens

Histocompatibility testing has been shown to predict acute rejection risk in steroid-based immunosuppression. However, little evidence exists of its ability to predict acute rejection risk in corticosteroid-free patients, with no evidence in early corticosteroid withdrawal (CSWD) under modern immunosuppression. The purpose of this study was to evaluate the ability of histocompatibility testing to identify patients at high risk for acute rejection after early CSWD.

METHODS

One hundred eighty-one patients were entered into six IRB-approved early CSWD regimens. Histocompatibility testing included serologic PRA, flow cytometric PRA testing by Class I and Class II MHC beads, and B cell crossmatching with pronase treatment. All rejection episodes were biopsy proven, and grading was assigned using Banff criteria. Influence of individual tests was examined using Chi square univariate and multivariate logistic regression analysis.

RESULTS

Median follow-up was 23.5 months (range 7-48 months). Of 181 patients, 16% were repeat transplant recipients, 36% received deceased donor renal transplants, 48% received living related donor renal transplants, and 16% received living unrelated transplants. Overall patient survival was 97%, and death-censored graft survival was 96.5%. Acute rejection rates in the entire follow-up period were 17.7%. 12.4% in primary transplant recipients and 37% in repeat transplant recipients. Multivariate analysis revealed that HLA AB and DR locus mismatching were associated with increased acute rejection risk. Similarly, serologic PRA analysis predicted acute rejection risk; however, flow cytometry crossmatching did not predict acute rejection risk. The greatest single influence on acute rejection risk appeared to be a flow cytometric B cell crossmatch (7.94-fold increased risk). In conclusion, histocompatibility testing can identify patients at high risk for acute rejection following early CSWD. HLA matching, serologic PRA testing, and flow cytometry-based B cell crossmatching can all be used to predict acute rejection risk.

Corticosteroid avoidance ameliorates lymphocele formation and wound healing complications associated with sirolimus therapy

INTRODUCTION

Sirolimus (RAPA) and corticosteroids (CS) both inhibit wound healing. To evaluate the possibility that RAPA and CS have additive effects on wound healing, we evaluated the effects of corticosteroid avoidance (CSAV) on wound healing complications in patients treated with RAPA.

METHODS

One hundred nine patients treated with a CSAV regimen (no pretransplantation or posttransplantation CS) were compared with a historical control group (n = 72) that received cyclosporine (CsA), mycophenolate mofetil (MMF), and CS. The CSAV group received low-dose CsA, MMF, RAPA, and thymoglobulin induction. Complications were classified as follows: wound healing complications (WHC) or infectious wound complications (IWC). WHC included lymphocele, hernia, dehiscence, diastasis, and skin edge separation. IWC included wound abscess and empiric antibiotic therapy for wound erythema.

RESULTS

The CSAV group was largely CS-free: 11% of patients received CS for rejection, 12% of patients received CS for recurrent disease, and 85% of patients are currently off CS. The CSAV group had a significantly lower incidence of WHC (13.7% vs 28%; P = .03) and lymphoceles (5.5% vs 16%; P = .02) than the control group. There was no difference in the incidence of IWC between the 2 groups. Patients who received CSAV were 18% less likely (P = .57) to develop any type of complication, 41% less likely (P = .20) to develop a WHC, and 71% less likely (P = .018) to develop a lymphocele.

CONCLUSIONS

CSAV in a RAPA-based regimen results in a marked reduction in WHC and lymphoceles. Therefore, CSAV provides a promising approach for addressing WHC associated with RAPA therapy.

Analysis of factors that influence survival with post-transplant lymphoproliferative disorder in renal transplant recipients: the Israel Penn International Transplant Tumor Registry experience

Significant mortality is associated with post-transplant lymphoproliferative disorder (PTLD) in kidney transplant recipients (KTX). Univariate/multivariate risk factor survival analysis of US PTLD KTX reported to Israel Penn International Transplant Tumor Registry from November 1968 to January 2000 was performed. PTLD presented 18 (median) (range 1-310) months in 402 KTX. Death rates were greater for those diagnosed within 6 months (64%) versus beyond 6 months (54%, p = 0.04). No differences in death risk for gender, race, immunosuppression, EBV, B or T cell positivity were identified. Death risk increased for multiple versus single sites (73% vs. 53%, hazards ratio (HR) 1.4). A 1-year increase in age increased HR for death by 2%. Surgery was associated with increased survival (55% vs. 0% without surgery) (p < 0.0001). Patients with allograft involvement, treated with transplant nephrectomy alone (n = 20), had 80% survival versus 53% without allograft removal (n = 15) (p < 0.001). Overall survival was 69% for allograft involvement alone versus 36% for other organ involvement plus allograft (n = 19 alive) (p < 0.0001). Death risk was greater for multiple site PTLD and increasing age, and risks were additive. Univariate analysis identified increased death risk for those not receiving surgery, particularly allograft involvement alone.

Body Weight Alterations Under Early Corticosteroid Withdrawal and Chronic Corticosteroid Therapy With Modern Immunosuppression

Weight gain is a well-known complication of corticosteroid maintenance therapy. The purpose of our study was to compare patterns of weight gain under chronic corticosteroid therapy (CCST) to those observed under early corticosteroid withdrawal (CSWD) in renal transplant recipients.

METHODS

Renal transplant recipients who underwent early CSWD in IRB-approved prospective trials were compared to a historical control group of patients receiving CCST who were matched for age, sex, and race.

RESULTS

One hundred sixty-nine patients with early CSWD were compared to 132 patients who received CCST. Mean population weight gain was significantly higher in CCST patients at 12 months (5.52 kg vs 3.05 kg, P < .05) posttransplant. Caucasian CSWD patients demonstrated a greater reduction in weight gain with CSWD than African Americans (mean weight decrease 2.9 vs 1.9 kg/patient, P < .05). Patients who were overweight (body mass index [BMI] 25-30) or obese (BMI > 30) demonstrated a greater reduction in weight gain with CSWD at 1 year (mean reduction in weight gain with CSWD 5.3 kg/patient and 4.4 kg/patient) than did patients of normal weight (BMI < 25; 0.1 kg/patient, P < .01 and <.05 versus BMI < 25).

CONCLUSIONS

Early CSWD patients gain significantly less weight than CCST patients following transplantation. Marked variations in the effect of early CSWD on weight gain may be observed due to race and pretransplant BMI. Caucasians and overweight patients demonstrate greater benefits from CSWD than African Americans and patients with normal BMI.

Outcomes of Patients With Rejection Post–Polyomavirus Nephropathy

INTRODUCTION

We sought to determine the effects of rejection in renal transplant recipients with polyomavirus nephropathy (PVN).

METHODS

SCr, biopsy findings, BKV serum and urine loads (Taqman PCR), and BKV antibody titers (HA inhibition assay) were analyzed by two-sample median tests and z tests in 11 patients with median follow-up of 7.3 (2.0 to 31.5) months post-PVN. All patients underwent immunosuppression reduction (ISR) as PVN treatment.

RESULTS

Post-PVN, 3 (27%) patients had five rejection episodes, with 80% being mild. Median time to rejection was 18 (2 to 60) weeks. One hundred percent of patients who experienced post-PVN rejection also experienced rejection pre-PVN. Rejection episode treatments consisted of: none in one, increased tacrolimus in two, IVIG in one, IVIG and increased tacrolimus in one. Median viral loads in patients with post-PVN rejection versus those without rejection were not different in serum (2.01 x 10(4) vs 9.00 x 10(4) BKV copies/mL; P = .22) or urine (5.37 x 10(5) vs 8.93 x 10(6) BKV copies/mL; P = .28). Median BKV antibody titers were slightly lower (16384 vs 32768 HA units; P = .02) and median SCr values were significantly higher (2.7 vs 1.9 mg/dL, P = .0003) in patients who had experienced post-PVN rejection. Graft losses occurred in one rejection-free patient (chronic allograft nephropathy) and in one patient who experienced multiple acute rejection episodes, humoral rejection, and worsening PVN.

CONCLUSIONS

Patients who experience rejection prior to PVN are at high risk of developing rejection post-ISR and post-PVN; however, low graft loss rates may still be achieved.

Effect of arsenic on benzo[a]pyrene DNA adduct levels in mouse skin and lung

Concomitant exposures to arsenic and polycyclic aromatic hydrocarbons (PAHs) such as benzo[a]pyrene (BaP) are widespread. While BaP acts by binding to and inducing mutations in critical sites on DNA, the mechanism(s) of arsenic carcinogenesis remains unknown. Data from epidemiological studies of arsenic copper smelter workers and arsenic ingestion in drinking water suggest a positive interaction for arsenic exposure and smoking and lung cancer. A previous in vitro study showed that arsenic potentiated the formation of DNA adducts at low doses of BaP and arsenic. The present study was conducted to test the effect of arsenic on BaP-DNA adduct formation in vivo. We hypothesized that arsenic co-treatment would significantly increase BaP adduct levels in C57BL/6 mouse target organs: skin and lung. Treatment groups were: five mice, -BaP/-arsenic; five mice, -BaP/+arsenic; 15 mice, +BaP/-arsenic; 15 mice, +BaP/+arsenic. Mice in the appropriate groups were provided sodium arsenite in drinking water (2.1 mg/l), ad libitum, for 13 days (starting 9 days before BaP treatment), and 200 nmol BaP/25 ml acetone (or acetone alone) was applied topically, once per day for 4 days. DNA was extracted from skin and lung and assayed by (32)P-postlabeling. Statistical comparisons were made using independent t-tests (unequal variances assumed). BaP-DNA adduct levels in the +BaP groups were significantly higher than -BaP controls. Arsenic co-treatment increased average BaP adduct levels in both lung and skin; the increase was statistically significant in the lung (P = 0.038). BaP adduct levels in the skin of individual animals were positively related to skin arsenic concentrations. These results corroborate our in vitro findings and provide a tentative explanation for arsenic and PAH interactions in lung carcinogenesis.

Significance of radiation exposure from work-related chest X-rays for epidemiological studies of radiation workers

BACKGROUND

Previous epidemiologic studies of workers at nuclear weapons facilities have not included X-ray exposures as part of the occupational radiation exposure. The research objective was to determine the contribution of work-related chest X-ray (WRX) exposure relative to the cumulative occupational radiation exposure.

METHODS

Cases and controls were identified from a cohort of workers whose employment began as early as 1943. Medical records for 297 subjects were used to determine the bone marrow dose from their X-ray examinations. Individual dose data, however, were only available for 45 workers. Bone marrow dose estimates were calculated by converting the entrance-skin-exposure (from X-ray procedures) and occupational exposure (from monitoring data) to dose.

RESULTS

Stereoscopic photofluorography delivered a bone marrow dose nearly 100 times that delivered by today's chest X-ray technique. Photofluorography was the predominant radiation source during the 1940s and 1950s. The cumulative WRX dose was, on average, 50 times their occupational doses. No correlation between occupational and WRX dose was found, but may be due to the small study size and incomplete dose data.

CONCLUSIONS

These findings illustrate the importance of including WRX doses in retrospective epidemiological studies of radiation workers, especially if photofluorographic chest X-rays were performed and occupational exposure to ionizing radiation is low.

Evaluation of the HUD lead hazard control grant program: early overall findings

This study evaluates the effectiveness of lead hazard control methods used in the Lead Hazard Control (LHC) grant program of U.S. Department of Housing and Urban Development. The LHC Program awards funds to local jurisdictions to address lead hazards in privately owned, low-income dwellings. Grantees in 14 cities, states, or counties collected environmental data in over 2600-treated dwellings making this the largest study of residential lead hazard control ever undertaken. Grantees employed a range of treatments, the most common being replacement of windows and repair of deteriorated lead-based paint. In this paper, dust lead loading levels and blood lead levels of children (6 months-6 years, if present) were observed at four periods of time (preintervention, immediate, and 6- and 12-months postintervention) in 1212 dwellings. Dust lead loading levels were also observed in a subset of these dwellings at 24- and 36-months postintervention. The geometric mean floor and window dust lead loadings declined at least 50 and 88% (P<0.0001), respectively, immediately postintervention. Three years later, floor dust lead loadings remained at or below the immediate postintervention levels. Window dust lead loadings had moderate increases, but remained substantially reduced from preintervention levels and below clearance standards. At 1 year after intervention, geometric mean age-adjusted blood lead levels had declined from 11.0 to 8.2 microg/dL, a 26% decline (P<0.0001). The LHC Program interventions produced blood lead declines similar to or greater than the percentage changes reported in earlier 1-year lead intervention studies.

A classification system for characterization of physical and non-physical work factors

A comprehensive evaluation of work-related performance factors is a prerequisite to developing integrated and long-term solutions to workplace performance improvement. This paper describes a work-factor classification system that categorizes the entire domain of workplace factors impacting performance. A questionnaire-based instrument was developed to implement this classification system in industry. Fifty jobs were evaluated in 4 different service and manufacturing companies using the proposed questionnaire-based instrument. The reliability coefficients obtained from the analyzed jobs were considered good (0.589 to 0.862). In general, the physical work factors resulted in higher reliability coefficients (0.847 to 0.862) than non-physical work factors (0.589 to 0.768).

Longitudinal risk of std acquisition in adolescent girls using a generalized estimating equations model

Background: To date, few studies have used a longitudinal approach in examining risk factors for STD acquisition in teenage girls. In the present study, we examined risk of STD acquisition in adolescent girls over a three-year period using longitudinal analyses.Methods: One hundred and seventy-four girls between the ages of 12 and 16 (mean age = 14.5) participated in a longitudinal study of adolescent romantic relationships. The racial composition of the subject pool was 80% African-American and 20% Caucasian. These girls were followed for three years at six-month intervals. By the end of the study, 127 of the girls were sexually experienced, and thus, were included in the analyses regarding risk for STDs. The risk for history of STD was evaluated using a generalized estimating equations (GEE) model, which allows for the inclusion of data from subjects with missing visits. The following independent variables were entered into the model: age, race, screening IQ score, qualitative cognitive functioning, perceptions of STD prevalence among female friends, and whether a condom was used at last intercourse. Additional independent variables included number of lifetime partners (4 or more lifetime partners, 2 to 3 lifetime partners, only one partner) and age of sexual debut (less than 14 years, 14-16 years, and 17 years and older), five factors from the Family Environment Scale, and three types of parental monitoring (direct, direct when with peers, and indirect).Results: The results of the longitudinal (GEE) model indicated that having a history of an STD was significantly related to a younger age of sexual debut (p <.01), having more partners (p <.0001), being African-American (p =. 01), and having a lower screening IQ score (p <.01).Conclusions: These results suggest that risk of STD is associated with both modifiable and non-modifiable variables. Race and intellectual functioning independently contributed to STD risk, stressing the importance of utilizing prevention programs that are culturally and developmentally specific. For example, less intelligent girls may need to have information presented in a more concrete manner, with a focus on the present rather than the future. The targets of these prevention programs should continue to emphasize delaying initiation, as well as partner selection. Finally, the fact that variables for STD acquisition in this longitudinal model are comparable to previous cross-sectional studies of STD acquisition suggests that these are potent predictors of risk.

Spontaneous micronucleus frequency and age: what are normal values?

Micronucleus frequency in epidemiological studies of human exposure has become a preferred biomarker. A generally recognized observation is that micronucleus frequency increases with age. One requirement for comparison of data, which is being generated in many countries, is some common agreement about what constitutes a typical or normal background frequency of micronuclei. This is also a requirement when examining any individual value, especially one which might be considered an outlier. A mean value for normal micronucleus frequency with age is developed via the analysis of multiple studies, all of which employed large population bases and generally were conducted with the intent of determining population values. The result is presented here, with the understanding that it may over- or under-estimate the actual values in certain populations.

Use of a field portable X-Ray fluorescence analyzer to determine the concentration of lead and other metals in soil samples

Field portable methods are often needed in risk characterization, assessment and management to rapidly determine metal concentrations in environmental samples. Examples are for determining: "hot spots" of soil contamination, whether dust wipe lead levels meet housing occupancy standards, and worker respiratory protection levels. For over 30 years portable X-Ray Fluorescence (XRF) analyzers have been available for the in situ, non-destructive, measurement of lead in paint. Recent advances made possible their use for analysis of airborne dust filter samples, soil, and dust wipes. Research at the University of Cincinnati with the NITON 700 Series XRF instrument (40 millicurie Cadmium 109 source, L X-Rays) demonstrated its proficiency on air sample filters (NIOSH Method No. 7702, "Lead by Field Portable XRF; limit of detection 6 microg per sample; working range 17-1,500 microg/m3 air). Research with lead dust wipe samples from housing has also shown promising results. This XRF instrument was used in 1997 in Poland on copper smelter area soil samples with the cooperation of the Wroclaw Medical Academy and the Foundation for the Children from the Copper Basin (Legnica). Geometric mean soil lead concentrations were 200 ppm with the portable XRF, 201 ppm with laboratory-based XRF (Kevex) and 190 ppm using atomic absorption (AA). Correlations of field portable XRF and AA results were excellent for samples sieved to less than 125 micrometers with R-squared values of 0.997, 0.957, and 0.976 for lead, copper and zinc respectively. Similarly, correlations were excellent for soil sieved to less than 250 micrometers, where R-squared values were 0. 924, 0.973, and 0.937 for lead, copper and zinc, respectively. The field portable XRF instrument appears to be useful for the determination of soil pollution by these metals in industrial regions.

An empirical comparison of lead exposure pathway models

Structural equation modeling is a statistical method for partitioning the variance in a set of interrelated multivariate outcomes into that which is due to direct, indirect, and covariate (exogenous) effects. Despite this model's flexibility to handle different experimental designs, postulation of a causal chain among the endogenous variables and the points of influence of the covariates is required. This has motivated the researchers at the University of Cincinnati Department of Environmental Health to be guided by a theoretical model for movement of lead from distal sources (exterior soil or dust and paint lead) to proximal sources (interior dust lead) and then finally to biologic outcomes (handwipe and blood lead). The question of whether a single structural equation model built from proximity arguments can be applied to diverse populations observed in different communities with varying lead amounts, sources, and bioavailabilities is addressed in this article. This reanalysis involved data from 1855 children less than 72 months of age enrolled in 11 studies performed over approximately 15 years. Data from children residing near former ore-processing sites were included in this reanalysis. A single model adequately fit the data from these 11 studies; however, the model needs to be flexible to include pathways that are not frequently observed. As expected, the more proximal sources of interior dust lead and handwipe lead were the most important predictors of blood lead; soil lead often had a number of indirect influences. A limited number of covariates were also isolated as usually affecting the endogenous lead variables. The blood lead levels surveyed at the ore-processing sites were comparable to and actually somewhat lower than those reported in the the Third National Health and Nutrition Examination Survey. Lessened bioavailability of the lead at certain of these sites is a probable reason for this finding.

The contribution of lead-contaminated house dust and residential soil to children's blood lead levels. A pooled analysis of 12 epidemiologic studies

In 1992, the U.S. Congress passed the Residential Lead-Based Paint Hazard Reduction Act, which requires the promulgation of health-based dust lead and soil lead standards for residential dwellings to prevent undue lead exposure in children. Unfortunately, the levels of lead in house dust and soil that are associated with elevated blood lead levels among U.S. children remain poorly defined. This pooled analysis was done to estimate the contributions of lead-contaminated house dust and soil to children's blood lead levels. The results of this pooled analysis, the most comprehensive existing epidemiologic analysis of childhood lead exposure, confirm that lead-contaminated house dust is the major source of lead exposure for children. These analyses further demonstrate that a strong relationship between interior dust lead loading and children's blood lead levels persists at dust lead levels considerably below the U.S. Department of Housing and Urban Development's current postabatement standards and the Environmental Protection Agency's guidance levels. Finally, these analyses demonstrate that a child's age, race, mouthing behaviors, and study-site specific factors influence the predicted blood lead level at a given level of exposure. These data can be used to estimate the potential health impact of alternative health-based lead standards for residential sources of lead exposure.

Reliability of questionnaire information measuring musculoskeletal symptoms and work histories

This study was designed to assess the test-retest reliability of a musculoskeletal symptom and work history (MSWH) questionnaire administered to 522 carpenters A 10% subgroup of carpenters completing the original interview was selected for the retest interview. The areas addressed included recall of work-related musculoskeletal symptoms, prior medical conditions, prior injuries, recall of work histories, and psychosocial items. The results show that for these sections of the MSWH questionnaire the observed agreements ranged from 75.5 to 97.0%, and the calculated kappa estimates ranged from 0.46 to 0.77. Injury to body regions, job specialty, and prior medical history had the highest kappa values of K = .70 or greater. Reliability of reporting frequency of job duties such as flooring and finishing was excellent, with kappa = 0.73 (95% confidence interval = 0.66, 0.80). Based on these results, the overall reliability of the MSWH questionnaire is very good.

Effect of chronic low-level exposure to jet fuel on postural balance of US Air Force personnel

This study used the postural stability technique to investigate the neurological effects of cumulative low-level exposure to raw JP-8 jet fuel vapor on aircraft maintenance personnel. All subjects performed two sets of four 30-second postural sway tests. The results of mean cumulative exposure levels (in parts per million +/- standard error of mean) were the following: naphthas, 1308 +/- 292; benzene, 21.2 +/- 5.7; toluene, 23.8 +/- 6.1; and m-,o-, p-xylene, 22.7 +/- 5.4. Covariate adjusted regression analysis of the exposed group data showed a statistically significant association (P < 0.05) between the solvents (benzene, toluene, and xylene) and increased postural sway response. For all solvent exposures, the "eyes closed, on foam" test provided the strongest association between sway length and JP-8 benzene (r2 range, 0.45 to 0.52), implying subtle influence on vestibular/proprioception functionalities.

Postural stability assessment in sewer workers

In this study, postural stability was measured with a microcomputer-based force platform as an indirect assessment of central nervous system effect in 28 sewer workers (age range 23.4 to 64.5 years, standard deviation of 8.7 years). All workers performed four 30-second postural sway tests. The organic-solvent exposure was measured by a photo-ionization detector. The photo-ionization detector was calibrated to measure volatile organic solvents in total benzene equivalence, and concentrations were measured in various parts of the plant. The mean exposure was .32 parts per million (ppm) benzene equivalent (range of .02 to .95 ppm, standard deviation .19 ppm). Based on a covariate adjusted linear multiple-regression model, a statistically significant (p < .05) positive correlation was demonstrated between postural sway and organic-solvent exposure. These workers also had increased postural sway compared with a nonexposed population. The statistically significant correlation between postural sway determinations and organic-solvent exposure was surprising given the very low exposures measured. It is possible that the organic-solvent exposure might not be the causative agent, but rather that the solvents themselves correlate with some other causative exposure, ie, total volatile organics as implicated in the cause of sick-building syndrome.

Effect of different vitamin A intakes on very-low-birth-weight infants

Formula-fed infants with birth weights < or = 1500 g (n = 61) were stratified by 250-g birth-weight ranges and randomly assigned to receive one of three preterm infant formulas (vitamin A contents of 820 IU, 1640 IU, or 2900 IU/MJ; 1 RE = 3.3 IU vitamin A activity) when subjects tolerated 0.314 MJ.kg-1.d-1. Experimental formula feedings were continued until infants weighed approximately 2 kg or until hospital discharge. Vitamin A status as indicated by serum retinol and retinol-binding protein (RBP) concentrations significantly decreased during experimental formula feeding at the lowest vitamin A intake. All subjects fed the formula providing the lowest vitamin A intake had hyporetinolemia (< 0.70 mumol/L, or < 20 micrograms/dL), which occurred less frequently (P < 0.05) with the intermediate (6 of 20) and the high (6 of 21) vitamin A intakes. Other outcome measures, including increases in weight, length, and head circumference, and ventilatory support and oxygen therapy, were not different among groups. After the end of the experimental formula-feeding period, all infants were fed standard infant formulas with a vitamin A content of 715 IU/MJ. In a subset of 19 of these infants, subsequent vitamin A status was monitored at ages 6-12 mo and was found to be comparable with that of older children and adults, regardless of the vitamin A content of the formula fed during hospitalization.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of three levels of vitamin D intake in preterm infants receiving high mineral-containing milk

Very low-birth weight (VLBW) infants fed high-calcium and high-phosphorus (10.74 and 6.93 mmol/MJ; 180 and 90 mg/100 kcal, respectively) infant formulas were randomized to one of three levels of vitamin D intake to approximate 200, 400, and 800 IU/day. Sixty-two infants completed the study (24 to 29 days), with actual mean daily vitamin D intakes of 161, 361, and 766 IU, respectively. Outcomes were not different by group: gains in body weight, length and head circumference, serum calcium, magnesium, phosphorus, alkaline phosphatase, osteocalcin, 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, and urine calcium:creatinine and magnesium:creatinine ratios. There were no radiographic fractures and/or rickets. A subset of 19 infants was followed between 173 and 380 days to determine descriptively if there was any delayed effect of earlier manipulation of vitamin D intake. They were fed standard infant formulas with a vitamin D content of 400 to 420 IU/L. No significant differences were present among the three groups, and data were combined. Serum 25-hydroxyvitamin D increased (p < 0.05), osteocalcin decreased (p < 0.05), and 1,25-dihydroxyvitamin D decreased (p = 0.06) at follow-up. Thus, for VLBZW infants fed high-calcium and high-phosphorus milk, an average daily vitamin D intake as low as 160 IU maintains normal and stable vitamin D status and normal physical growth, biochemical and hormonal indexes of bone mineral metabolism, and skeletal radiographs versus randomized infants receiving about 400 or 800 IU of vitamin D per day. On follow-up, vitamin D status remained normal for > or = 6 months while infants received < 400 IU of vitamin D per day.

Clean-up of lead in household carpet and floor dust

Methods to remove lead-containing dust were tested on carpets from homes of children with high blood lead and on new carpets artificially contaminated in the laboratory. The household carpets could not be cleaned effectively by repetitive vacuuming with HEPA-filtered cleaners. The lead concentration in the removed dust remained about the same from the initial cleaning (1 min/m2) to the final cleaning (total cleaning time of 10 min/m2). The lead loading on the surface of the carpets often increased during cleaning because vacuuming brought lead from deeper in the carpet to the surface. Over 95% of the total dust was removed from bare wooden floors by dry vacuuming (5 min/m2). For linoleum, more than 75% was removed by vacuuming for 5 min/m2. However, little was removed in vacuuming after the initial two minutes and about 20% was removed in a final wet-washing step. HEPA-vacuuming of the laboratory-contaminated carpets revealed that two of the commercially available vacuum cleaners tested were essentially equivalent and each removed significantly more dust than a third vacuum during a total cleaning time of 10 min/m2. Cleaning for 6 min/m2 was necessary to remove more than 70% of the embedded dust by the two more efficient vacuums. Cleaning efficiencies were about the same for short pile and sculptured carpets. It was concluded that it may be more practical to replace rather than clean carpets. HEPA-vacuum cleaning of carpets was shown to increase lead dust on the surface under some conditions.

Sequential serum aluminum and urine aluminum: creatinine ratio and tissue aluminum loading in infants with fractures/rickets

Aluminum toxicity is associated with the development of bone disorders, including fractures, osteopenia, and osteomalacia. Fifty-one infants with a mean (+/- SEM) birth weight of 1007 +/- 34 g, gestational age of 28.5 +/- 0.3 weeks, and serial radiographic documentation at 3, 6, 9, and 12 months for the presence (n = 16) or absence (n = 35) of fractures and/or rickets were studied at the same intervals to determine the serial changes in serum aluminum concentrations and urine aluminum-creatinine ratios. Autopsy bone samples were used to determine the presence of tissue aluminum. Serum aluminum concentrations from 46 infants were stable and similar between groups, with mean values between 15 and 22 micrograms/L. Urine aluminum-creatinine (micrograms per milligram) ratios from 14 infants were higher in infants with fractures and/or rickets (0.26 +/- 0.06 vs 0.12 +/- 0.04) at onset, and rate of decrease in aluminum-creatinine ratio was faster in infants without fractures and/or rickets. All but three infants were tolerating complete enteral feeding at all sampling points. One infant who received aluminum-containing antacid had marked increase in serum aluminum to 83 micrograms/L while urine aluminum-creatinine ratio increased from 0.09 to a peak of 8.53. Vertebrae from three infants at autopsy (full enteral feeding was tolerated for 37 and 41 days in two infants, respectively) showed aluminum deposition in the zone of provisional calcification and along the newly formed trabecula.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of work load and respirator wear on postural stability, heart rate, and perceived exertion

The effects on postural stability (sway) were investigated for different work loads under conditions of wearing a full facepiece respirator and not wearing any respiratory protection device. Fifteen subjects accomplished light (40 W), moderate (85 W), and heavy (125 W) work loads under the two conditions. Measurements of postural sway were made immediately after each load by using a multicomponent, strain gage-type force platform. Changes in each subject's movement pattern of the center of pressure were quantitated and compared to their initial baseline sway tests. Each subject's heart rate and perceived exertion were also recorded during each condition. A statistically significant effect (p = 0.007) caused by work load was observed for total length of sway with or without a respirator. An interaction approaching statistical significance (p = 0.056) between work load and respirator use was found. This indicated that sway increased more quickly and in a more consistently linear fashion with increasing work load under the respirator condition (p = 0.02) compared to the nonrespirator condition. The results from the respirator condition showed linear increases in postural sway length across the entire range of work loads, but sway length in the nonrespirator condition showed an increase only at 125-W work loads. The greater increase in sway during the postural balance test could be attributable to the increasing work load-induced proprioceptive fatigue effect on the nervous system's ability to process signals from proprioception systems incongruent with body sway. The heart rate was significantly higher during respirator wear (an increase in heart rate averaging 5.62 beats/min).(ABSTRACT TRUNCATED AT 250 WORDS)

Sequential concentrations of copper and ceruloplasmin in serum from preterm infants with rickets and fractures

Concentrations of copper (Cu) and ceruloplasmin in serum were measured serially in 49 preterm infants with mean (+/- SEM) birth weights of 979 +/- 33 g and gestational ages of 28.4 +/- 0.3 weeks at three, six, nine, and 12 months postpartum. Serial radiographic studies showed 17 infants with (group A) and 32 infants without (group B) rickets or fractures. Cu and ceruloplasmin concentrations in serum also were measured in 21 healthy term infants (group C) with birth weights 3668 +/- 98 g at three, six, and 12 months postpartum. Analyses of covariance of serial changes in these serum variables--taking into account such potential covariates as differences in gestational age, birth weight, initial weight and length, changes in weight and length during the study, the duration of parenteral nutrition, and increased enteral copper intake--showed both groups of preterm infants had significantly lower concentrations of Cu in serum up to age six months and ceruloplasmin up to age three months (P less than 0.001) when compared with term infants. By one year of age, Cu and ceruloplasmin concentrations in serum in all groups had increased significantly (P less than 0.001), into the adult range, and were not significantly different among groups. These data document a maturational lag in copper metabolism in small, preterm infants. Changes in concentrations of Cu and ceruloplasmin in serum were significantly correlated (r = 0.92, P less than 0.001) but were not significantly different between preterm infants with and without rickets or fractures at each age.

Osmotic load from glucose polymers

Glucose polymer is a carbohydrate source with variable chain lengths of glucose units which may result in variable osmolality. The osmolality of two commercial glucose polymers was measured in reconstituted powder infant formulas, and the change in osmolality of infant milk formulas at the same increases in energy density (67 kcal/dL to 81 and 97 kcal/dL) from the use of additional milk powder or glucose polymers was compared. All samples were prepared from powders (to nearest 0.1 mg), and osmolality was measured by freezing point depression. For both glucose polymers the within-batch variability of the measured osmolality was less than 3.5%, and between-batch variability of the measured osmolality was less than 9.6%. The measured osmolality varies linearly with energy density (p less than 0.001) and was highest in infant formula reconstituted from milk powder alone. However, there exist significant differences in the measured osmolality between different glucose polymer preparations. At high energy densities (greater than or equal to 97 kcal/dL), infant milk formulas prepared with milk powder alone or with the addition of certain glucose polymer preparation may have high osmolality (greater than or equal to 450 mosm/kg) and theoretically predispose the infant to complications of hyperosmotic feeds.

Urinary hydroxyproline in infants with and without fractures/rickets

Molar ratios of peptide-bound and free hydroxyproline:creatinine (OHPr:Cr) in urine were measured at 3, 6, 9, and 12 months of age in two groups of very-low-birthweight (VLBW less than or equal to 1500 g) infants. Group A (15 infants) had radiographically confirmed fractures and (or) rickets (F/R); Group B (17 infants) did not. The urinary peptide-bound OHPr:Cr ratio varied widely within groups and was greatest at three months in both groups: A = 0.81 +/- 0.45 and B = 0.55 +/- 0.32 (mean +/- SD). The ratio decreased with increasing postnatal age for each group but was not statistically different between groups throughout the study. The urinary free OHPr:Cr ratio also was greatest at age three months (A = 0.32 +/- 0.15 and B = 0.53 +/- 0.46), rapidly decreasing afterwards, and was not statistically different between groups throughout the study. We conclude that, in VLBW infants, bone turnover as indicated by the urinary peptide-bound OHPr:Cr ratio is highest during early infancy; however, the wide range of values for this ratio suggests that its use alone is not sufficient for detection of F/R in VLBW infants. The rapid decrease in free OHPr:Cr ratio is presumably related to the maturation of renal tubular function.

Urinary hydroxyproline in infants with and without fractures/rickets

Molar ratios of peptide-bound and free hydroxyproline:creatinine (OHPr:Cr) in urine were measured at 3, 6, 9, and 12 months of age in two groups of very-low-birthweight (VLBW less than or equal to 1500 g) infants. Group A (15 infants) had radiographically confirmed fractures and (or) rickets (F/R); Group B (17 infants) did not. The urinary peptide-bound OHPr:Cr ratio varied widely within groups and was greatest at three months in both groups: A = 0.81 +/- 0.45 and B = 0.55 +/- 0.32 (mean +/- SD). The ratio decreased with increasing postnatal age for each group but was not statistically different between groups throughout the study. The urinary free OHPr:Cr ratio also was greatest at age three months (A = 0.32 +/- 0.15 and B = 0.53 +/- 0.46), rapidly decreasing afterwards, and was not statistically different between groups throughout the study. We conclude that, in VLBW infants, bone turnover as indicated by the urinary peptide-bound OHPr:Cr ratio is highest during early infancy; however, the wide range of values for this ratio suggests that its use alone is not sufficient for detection of F/R in VLBW infants. The rapid decrease in free OHPr:Cr ratio is presumably related to the maturation of renal tubular function.

Serum alkaline phosphatase and serum zinc concentrations in preterm infants with rickets and fractures

This study aimed to determine the longitudinal changes in serum zinc concentrations and the relationship between serum alkaline phosphatase (AP) activity and serum zinc concentrations in small preterm infants. The total serum AP and serum zinc concentrations were determined serially at 3, 6, 9, and 12 months in 72 infants with mean (+/- SEM) birth weights of 1000 +/- 29 g and gestational ages of 28.6 +/- 0.3 weeks. Twenty-four of 72 infants had radiographic evidence of rickets and/or fractures (R/F). In infants with R/F, group mean (+/- SEM) serum AP (371 +/- 42 U/L) and serum zinc (12.5 +/- 1.0 mumol/L) concentrations were significantly higher at 3 months compared with infants in the non-R/F group (193 +/- 12 U/L and 9.6 +/- 0.3 mumol/L, respectively). During the study, the serum AP concentrations decreased, and the serum zinc concentrations increased; both stabilized after 6 months. The serum AP concentrations were not related to the serum zinc concentrations. We speculate that in preterm infants, an increased bone turnover and a release of tissue (bone) zinc may contribute to the higher group mean serum AP and serum zinc concentrations at the time of diagnoses in infants with R/F compared with those infants without R/F.

Response of preterm infants to aluminum in parenteral nutrition

Twenty-five preterm infants with birth weights (BW) 540 to 2280 g (20 with birth weight less than 1500 g) and gestational ages 24 to 37 weeks, were studied to determine the response to 2 levels of aluminum (Al) loading from currently unavoidable contamination of various components of parenteral nutrition (PN) solution. High Al loading group (H) received solutions with measured Al content of 306 +/- 16 micrograms/liter and low A1 loading group (L) received solutions with 144 +/- 16 micrograms A1/liter. Urine Al:Creatinine (Al:Cr) ratios (micrograms:mg) became elevated and significantly higher in H (1.6 +/- 0.38 vs 0.5 +/- 0.1, p less than 0.05) at the third sampling point (mean 19 days). Serum Al concentrations were highest at onset in both groups and stabilized with study but remained consistently higher than the normal median of 18 micrograms/liter. Calculated urine Al excretion were consistently low and were 34 +/- 6% vs 28 +/- 5% in the H and L groups, respectively. One infant in the L group who died 39 days after termination of above study showed the presence of A1 in bone trabeculae and the presence of excessive unmineralized osteoid along the trabeculae. We conclude that small preterm infants are able to increase urine Al excretion with increased Al load. However urine Al excretion is incomplete with bone deposition of Al and persistently elevated serum Al concentrations.

Serum vitamin D metabolites in very low birth weight infants with and without rickets and fractures

Seventy-one very low birth weight (less than or equal to 1500 gm) infants were studied to determine the sequential changes in serum vitamin D metabolite concentrations between infants with and without radiographically documented rickets, fractures, or both (R/F). Usual intake of vitamin D included 20 IU/kg/day from parenteral nutrition or 400 IU/day supplementation with enteral feeding. Radiographs of both forearms and serum samples were obtained at 3, 6, 9, and 12 months. Twenty-two infants had R/F. At 3 months, significantly lower mean (+/- SEM) serum phosphorus levels (4.5 +/- 0.4 vs 6.1 +/- 0.2 mg/dl), higher 1,25-dihydroxyvitamin D (1,25-[OH]2D) concentrations (96 +/- 5 vs 77 +/- 4 pg/ml), and higher free 1,25-(OH)2D index (1,25-[OH]2D:vitamin D binding protein ratio; 5.2 +/- 0.3 x 10(5) vs 4.0 +/- 0.2 x 10(5] were found in the R/F group. These values returned to normal and were similar between groups on subsequent measurements. Serum calcium, magnesium, and 25-hydroxyvitamin D (25-OHD) concentrations were normal and similar between groups. In both groups, serum vitamin D binding concentrations increased initially but remained stable and normal beyond 6 months. We conclude that in very low birth weight infants with R/F, the vitamin D status (as indicated by serum 25-OHD concentrations) is normal, and that lowered serum phosphorus levels, higher serum 1,25-(OH)2D levels, and a higher free 1,25-(OH)2D index support the thesis that mineral deficiency (especially of phosphorus) may be important in the pathogenesis of R/F in small preterm infants.

Minimal vitamin D and high calcium and phosphorus needs of preterm infants receiving parenteral nutrition

Preterm infants (birth weight, 1,089 +/- 91 g; gestational age, 28.9 +/- 0.7 weeks; mean +/- SEM) with mixed medical and surgical indications for parenteral nutrition (PN) were observed to determine the adequacy of infusates with fixed, low-dose vitamin D (25 IU/dl) and two combinations of calcium and phosphorus. The duration of low-dose vitamin D PN ranged from 5 to 52 days, with a median of 27 days. Twelve infants were randomly assigned to low (standard) Ca and P doses (5 mM each; 20 mg/dl of Ca and 15.5 mg/dl of P) and 13 high Ca and P doses (15 mM each; 60 mg/dl of Ca and 46.5 mg/dl of P). The maximum daily vitamin D intake was similar for both groups (31 +/- 1.3 versus 33 +/- 1.2 IU/kg). Vitamin D status in either group, as indicated by serum 25-hydroxyvitamin D (25-OHD) concentrations, was normal. There was no significant difference in observed changes of serial measurements of serum calcium, magnesium, phosphorus, alkaline phosphatase, creatinine (Cr), 25-OHD, and vitamin D-binding protein concentrations or urinary Ca:Cr and Mg:Cr ratios. In the low-dose Ca and P group, the serum P level was consistently less than 4 mg/dl in five infants, serum 1,25-dihydroxyvitamin D concentrations were higher, and tubular reabsorption of phosphorus was consistently greater than 95% and significantly higher than in the high-dose Ca and P groups. Severe bone demineralization apparent on X-ray occurred in two infants, with a fractured distal left ulna in one of the two infants.(ABSTRACT TRUNCATED AT 250 WORDS)

Sequential bone mineral content in small preterm infants with and without fractures and rickets

Seventy-four infants with birth weights 1009 +/- 28 grams and gestational age 28.6 +/- 0.3 weeks (M +/- SEM) were studied prospectively to test the hypotheses that bone mineral content (BMC) measured by photon absorptiometry, would be: (1) lower in very low birth weight (VLBW) infants with radiographic evidence of fractures and/or rickets (F/R), and (2) will continue to be lower over the first year when compared to VLBW infants without F/R. BMC and bone width (BW) of the distal one-third of left radius and ulna were measured at 5 weeks (n = 8), 14 weeks (n = 61), 26 weeks (n = 58), 40 weeks (n = 59), and 1 year (n = 52). Standardized radiographs of both forearms, and weight, length, and head circumference were also determined at each study age. Investigators and technicians involved in the photon absorptiometry measurements were unaware of the radiographic findings and vice versa. Twenty-three of 74 infants were found to have F/R. BMC of studied infants remained markedly below our previously determined range of "intrauterine bone mineralization," even at 26 weeks after birth. There was no significant difference in BMC or BW between infants with and without F/R, either at the time of confirmation of F/R or during early follow-up; however, BMC was lower at greater than or equal to 6 months and BW was lower at greater than or equal to 9 months in infants with F/R. We suggest that the extremely low BMC measurements in early infancy predispose all VLBW infants to fractures and rickets.

Urinary sodium excretion in young infants: role of gestational and postnatal ages

Fractional urinary sodium excretion (FENa) and urinary sodium excretion (UNaE) were determined 88 times in 42 healthy, appropriate weight-for-gestational age infants. Gestational ages (GA) were 28-41 weeks; birthweights were 930-4135 g. Nineteen preterm infants were studied serially a total of 59 times between 1 and 55 days after birth. During the first 4 days after birth, multiple hierarchical regression analyses showed that FENa and UNaE were inversely related to GA (P less than 0.001). Postnatal age (PN) was not significantly related to FENa or UNaE. However the effect of GA on FENa and UNaE was not significantly greater than the effect due to postnatal age (PA) (P = 0.31 and P = 0.80, respectively). UNaE (1.6 +/- 0.2 mmol/kg per day) was significantly greater than sodium intake (1.1 +/- 0.2 mmol/kg per day) at 2.6 +/- 0.2 days (P less than 0.05). Longitudinal studies extending beyond 4 days indicated that GA and PA had interactive effects on FENa and UNaE; hence the contribution for a given GA was dependent on PA (and vice versa). Sodium intake remained stable (average 1.8 mmol/kg per day) beyond 7 days after birth and was consistently greater than UNAE (P less than 0.01). It is suggested that in healthy preterm infants beyond 2 weeks PA, a sodium intake of 2-3 mol/kg per day may be adequate to meet the renal sodium losses.

Vitamin D requirement in infants receiving parenteral nutrition

The adequacy of low dose vitamin D (25 IU/dl) parenteral nutrition (PN) solution was studied in 18 infants. All infants had surgical indications for PN. The birth weights were 2810 +/- 135 g and gestational ages 37.4 +/- 0.5 wk (mean +/- SEM). Duration of study ranged from 5 to 175 days. Thirteen infants were studied for up to 6 weeks and five infants for 71 to 175 days. Results showed that studied infants maintained growth along normal percentiles for weight, length, and head circumference. Vitamin D status as indicated by serum 25 hydroxyvitamin D (25 OHD) rose from 15 +/- 1.9 ng/ml to 26 +/- 2.8 ng/ml, mean +/- SEM (p less than 0.001) after 9 days, and remained normal up to 6 months. Five infants with biochemical liver dysfunction also had normal serum 25 OHD concentrations, indicating the hepatic 25 hydroxylation process was not severely impaired. Serum total and ionized calcium, phosphorus, and vitamin D-binding protein concentrations were normal. Serum magnesium was mildly elevated in five infants (2.6 to 3 mg/dl) on one occasion and resolved spontaneously. Serum alkaline phosphatase (AP) concentrations rose above baseline values in 12 of 17 infants, but remained within normal range (less than 400 IU/liter at 30 degrees C). Another infant with markedly elevated AP values died from liver dysfunction. Radiographs of the forearms were normal except for marked demineralization in one infant in spite of normal 25 OHD concentrations. We conclude that 25 IU vitamin D/dl of nutrient infusate is adequate to maintain normal vitamin D status, as indicated by normal serum 25 OHD concentrations in infants receiving PN for as long as 6 months.

Parenteral nutrition for infants: effect of high versus low calcium and phosphorus content

Calcium (Ca) and phosphorus (P) homeostasis were determined in 18 infants (birth weight, 2,810 +/- 135 g; gestational age, 37.4 +/- 0.5 weeks; mean +/- SEM) who received high or low Ca and P content (Ca, P) parenteral nutrition (PN) with a fixed, low dose of vitamin D (25 IU/dl). Nine infants were randomized into low (standard) Ca, P (20 mg Ca and 15.5 mg P/dl) and nine into high Ca, P (60-80 mg Ca and 46.5-62 mg P/dl) PN, and then were studied for up to 6 weeks. The high Ca, P group had stable serum 1,25 dihydroxyvitamin D [1,25(OH)2D], which consistently remained within the normal range (less than 116 pg/ml). Tubular reabsorption of phosphorus (TRP) also was stable and remained consistently less than 90%. The low Ca, P group had elevated and higher 1,25(OH)2D (p = 0.03) than the high Ca, P group. The mean serum 1,25(OH)2D concentration rose from 32 to 112, 115, and 133 pg/ml over a period of 6 weeks. TRP also was higher (p = 0.02) and remained consistently greater than 90%. There were no significant differences between groups in serum parathyroid hormone, calcitonin, Ca, Mg, P, alkaline phosphatase, vitamin D binding protein, and 25 hydroxyvitamin D concentrations; urine Ca/creatinine and Mg/creatinine ratios, and fractional excretion of sodium (Na). Thus, a "high" Ca (60 mg/dl) and P (46.5 mg/dl) content in PN solutions can result in stable serum 1,25(OH)2D and TRP, presumably reflecting minimal stress to Ca and P homeostatic mechanisms without further increase in urinary Ca excretion.

Response to aluminum in parenteral nutrition during infancy

The response to aluminum loading from parenteral nutrition (PN) solutions was determined in 20 infants with gestational ages 29 to 41 weeks and birth weights 880 to 3630 gm. Mean duration of PN was 43 days (range 5 to 175 days). Ten infants received a high Al load (from an experimental high calcium- and phosphorus-containing PN solution, with a measured Al content of 306 +/- 26 micrograms/L (mean +/- SE), n = 11), for up to 6 weeks. Ten infants received a lower Al load (from standard Ca-P solutions, measured Al content 144 +/- 16 micrograms/L, n = 11). Five infants received PN with a low Al load for longer than 6 weeks. The mean urine Al/creatinine (Cr) ratio (micrograms/mg) increased threefold, from 0.3 +/- 0.09 to 0.97 +/- 0.17 during PN in the entire group (P less than 0.001), and was significantly higher in infants who received greater Al loading (P less than 0.001). There was no significant difference between preterm and term infants in the rate of change in urine Al/Cr during the study. Urine Al was calculated to account for less than 50% of Al load. During the study, serum Al concentrations ranged from 6 to 318 micrograms/L (median 37 micrograms/L, compared with the median 18 micrograms/L for normal infants and children). Serum Al concentrations were not significantly changed during the study, or between infants in high or lower Al loading groups. Vertebrae from autopsy of two infants who received the lower Al containing PN for 71 and 152 days, respectively, stained positive for Al at the bone mineralization front. Thus, currently used PN solutions are contaminated with Al, urine Al concentration is higher with higher Al loading, and is not different in term and preterm infants. We suggest that renal elimination of Al in infants is incomplete, as assessed by lower urine Al excretion versus load, elevated serum Al concentration, and bone deposition of Al.

Relationship between hematopoietic parameters and behavioral measures in lead-exposed rats

The effects of low level lead (Pb) exposure on learning tasks in developing rats were investigated and the results correlated with individual hematopoietic indices. Pups received exposure via the dams milk; dams were exposed to either 0-, 545-, or 1090-ppm Pb during the lactation period. At Day 30 of age, half of the high Pb group was placed on distilled water; the remaining groups continued on the same exposure regimens as their dams. On Days 20, 30, and 90, blood samples for all rats were obtained via cardiac puncture. Each sample was analyzed for Pb concentration, free erythrocyte protoporphyrin (FEPs), hematocrit, and hemoglobin. Beginning at Day 90, all rats were tested on a battery of tasks designed to investigate the following questions: (1) to what degree lead exposure interferes with reversal learning; (2) whether changing of task requirements adversely affects acquisition of a new task; (3) to what extent task difficulty contributes to lead-induced deficits; and (4) whether lead exposure affects the capacity to retain information over short or long periods of time. The actual testing paradigms included spatial discrimination with reversal, visual discrimination with reversal, and visual discrimination task with delay. No significant differences were observed among any of the groups on any of the tasks. Correlation of individual learning scores with individual measures of hematopoietic function also failed to reach significance. These findings indicate that at low exposure levels, lead has little appreciable effect on learning and memory function as measured by these tasks.