A sleeve and bulk method for fabrication of photonic structures with features on multiple length scales.

Traditional photonic structures such as photonic crystals utilize (a) large arrays of small features with the same size and pitch and (b) a small number of larger features such as diffraction outcouplers. In conventional nanofabrication, separate lithography and etch steps are used for small and large features in order to employ process parameters that lead to optimal pattern transfer and side-wall profiles for each feature-size category, thereby overcoming challenges associated with reactive ion etching lag. This approach cannot be scaled to more complex photonic structures such as those emerging from inverse design protocols. Those structures include features with a large range of sizes such that no distinction between small and large can be made. We develop a sleeve and bulk etch protocol that can be employed to simultaneously pattern features over a wide range of sizes while preserving the desired pattern transfer fidelity and sidewall profiles. This approach reduces the time required to develop a robust process flow, simplifies the fabrication of devices with wider ranges of feature sizes, and enables the fabrication of devices with increasingly complex structure.

Sexual risk and HIV testing disconnect in men who have sex with men (MSM) recruited to an online HIV self-testing trial.

OBJECTIVES: We report the frequency of previous HIV testing at baseline in men who have sex with men (MSM) who enrolled in an HIV self-testing (HIVST) randomized controlled trial [an HIV self-testing public health intervention (SELPHI)]. METHODS: Criteria for enrolment were age ≥ 16 years, being a man (including trans men) who ever had anal intercourse (AI) with a man, not being known to be HIV positive and having consented to national HIV database linkage. Using online survey baseline data (2017-2018), we assessed associations with never having tested for HIV and not testing in the previous 6 months, among men who reported at least two recent condomless AI (CAI) partners. RESULTS: A total of 10 111 men were randomized; the median age was 33 years [interquartile range (IQR) 26-44 years], 89% were white, 20% were born outside the UK, 0.8% were trans men, 47% were degree educated, and 8% and 4% had ever used and were currently using pre-exposure prophylaxis (PrEP), respectively. In the previous 3 months, 89% reported AI and 72% reported CAI with at least one male partner. Overall, 17%, 33%, 54%, and 72% had tested for HIV in the last 3 months, 6 months, 12 months and 2 years, respectively; 13% had tested more than 2 years ago and 15% had never tested. Among 3972 men reporting at least two recent CAI partners, only 22% had tested in the previous 3 months. Region of residence and education level were independently associated with recent HIV testing. Among current PrEP users, 15% had not tested in the previous 6 months. CONCLUSIONS: Most men in SELPHI, particularly those reporting at least two CAI partners and current PrEP users, were not testing in line with current UK recommendations. The results of the trial will inform whether online promotion of HIVST addresses ongoing testing barriers.

HIV self-testing intervention experiences and kit usability: results from a qualitative study among men who have sex with men in the SELPHI (Self-Testing Public Health Intervention) randomized controlled trial in England and Wales.

OBJECTIVES: SELPHI (HIV Self-Testing Public Health Intervention) is the largest randomized controlled trial (RCT) of HIV self-testing (HIVST) in a high-income setting to date, and has recruited 10 000 men who have sex with men (cis- and transgender) and transgender women who have sex with men. This qualitative substudy aimed to explore how those utilizing self-tests experience HIVST and the implications for further intervention development and scale-up. This is the first qualitative study in Europe investigating experiences of HIVST among intervention users, and the first globally examining the experience of using blood-based HIVST. METHODS: Thirty-seven cisgender MSM SELPHI participants from across England and Wales were purposively recruited to the substudy, in which semi-structured interviews were used to explore testing history, HIVST experiences and intervention preferences. Interviews were audio-recorded, transcribed and analysed through a framework analysis. RESULTS: Men accessed the intervention because HIVST reduced barriers related to convenience, stigma and privacy concerns. Emotional responses had direct links to acceptability. Supportive intervention components increased engagement with testing and addressed supportive concerns. HIVST facilitated more frequent testing, with the potential to reduce sexually transmitted infection (STI) screening frequency. Substudy participants with an HIV-positive result (n = 2) linked to care promptly and reported very high acceptability. Minor adverse outcomes (n = 2; relationship discord and fainting) did not reduce acceptability. Ease of use difficulties were with the lancet and the test processing stage. CONCLUSIONS: Intervention components shaped acceptability, particularly in relation to overcoming a perceived lack of support. The intervention was broadly acceptable and usable; participants expressed an unexpected degree of enthusiasm for HIVST, including those with HIV-positive results and individuals with minor adverse outcomes.

Respiration resolved imaging with continuous stable state 2D acquisition using linear frequency SWEEP.

PURPOSE: To investigate the potential of continuous radiofrequency (RF) shifting (SWEEP) as a technique for creating densely sampled data while maintaining a stable signal state for dynamic imaging. METHODS: We present a method where a continuous stable state of magnetization is swept smoothly across the anatomy of interest, creating an efficient approach to dense multiple 2D slice imaging. This is achieved by introducing a linear frequency offset to successive RF pulses shifting the excited slice by a fraction of the slice thickness with each successive repeat times (TR). Simulations and in vivo imaging were performed to assess how this affects the measured signal. Free breathing, respiration resolved 4D volumes in fetal/placental imaging is explored as potential application of this method. RESULTS: The SWEEP method maintained a stable signal state over a full acquisition reducing artifacts from unstable magnetization. Simulations demonstrated that the effects of SWEEP on slice profiles was of the same order as that produced by physiological motion observed with conventional methods. Respiration resolved 4D data acquired with this method shows reduced respiration artifacts and resilience to non-rigid and non-cyclic motion. CONCLUSIONS: The SWEEP method is presented as a technique for improved acquisition efficiency of densely sampled short-TR 2D sequences. Using conventional slice excitation the number of RF pulses required to enter a true steady state is excessively high when using short-TR 2D acquisitions, SWEEP circumvents this limitation by creating a stable signal state that is preserved between slices.

Associations of cancer mortality with halomethanes in drinking water.

Associations between site- and sex-specific county cancer mortality rates and levels of trihalomethanes (THM's) in drinking water were examined after adjustment of rates for the influence of multiple socioeconomic, industrial, and demographic factors. U.S. counties with sampled supplies were grouped by percent of the county population receiving water from the supply, as well as by region of the country. For two sites (bladder and lung), county rates were also adjusted for the activity level in specific high-risk industries. Positive correlations with THM levels were observed for several cancers, including bladder and brain cancers in both sexes, and non-Hodgkin's lymphoma and kidney cancer in males. Stomach cancer in females showed a negative association. Bladder cancer mortality rates showed the strongest and most consistent association with a THM exposure index, after control for differences in social class, ethnic group, urban versus rural residence, region of the United States, and industrialization of the county. These ecologic associations suggested that further evaluation in analytic investigations is warranted.

Central regulation of the hypothalamic-pituitary-adrenal axis during fetal development in the Guinea-pig.

We have previously shown that the foetal guinea-pig hypothalamic-pituitary-adrenal (HPA) axis is activated near the time of parturition and that this is associated with changes in limbic glucocorticoid receptors (GR) and mineralocorticoid receptors. In the present study, we hypothesized that the foetal hypothalamic paraventricular nucleus (PVN) and pituitary contribute significantly to foetal HPA drive but that these areas remain sensitive to negative feedback by circulating glucocorticoids in late gestation. However, we observed decreased corticotrophin-releasing hormone mRNA expression in the PVN and decreased pro-opiomelanocortin (POMC) mRNA levels in the anterior pituitary with advanced gestational age. The reduction in POMC mRNA expression was likely the result of negative feedback via circulating glucocorticoids because GR mRNA was unchanged during development in the foetal pituitary. Furthermore, we found that maternally administered glucocorticoids significantly decreased foetal pituitary POMC mRNA expression in a dose-dependent manner at gestational day (gd) 62 with male foetuses being more sensitive to these effects. These findings show that the foetal HPA axis remains highly sensitive to glucocorticoid feedback even as plasma adrenocorticotropic hormone and cortisol levels are elevated at the end of gestation.

Hepatocyte growth factor (HGF) adsorption kinetics and enhancement of osteoblast differentiation on hydroxyapatite surfaces.

Hepatocyte growth factor (HGF) is a growth factor that promotes angiogenesis (tissue vascularization), cell motility, and cell differentiation, making it a potentially beneficial coating for bone implants. However, very little is known about maximizing HGF attachment to surfaces of tissue-engineered scaffolds. Here, we examine methods and kinetics of HGF adsorption onto a dense hydroxyapatite (HA) surface (used in bone implants) and determine the influence of HGF coating on osteoblast phenotype/differentiation. We demonstrate that incubating HA with HGF in solution (and not allowing the solution to dry) resulted in maximal surface adsorption that was not enhanced by extending incubation time beyond 2 days. Daily shaking of the coated HA surface did not remove adsorbed HGF. To further examine the effect of HA on osteoblast phenotype, MC3T3-E1 preosteoblasts were seeded onto HA or HGF-HA surfaces. Gene expression analyses indicate that HGF coating enhanced osteoblast differentiation as demonstrated by increased runx2 (a transcription factor important for osteoblast lineage and differentiation), alkaline phosphatase (marker of mid stage differentiation) and osteocalcin (marker of late stage differentiation) mRNA levels. Taken together, our results demonstrate that HGF can serve as an excellent bone implant coating based on its ability to readily adsorb to HA surfaces, maintain integrity over time, and enhance osteoblast differentiation.

Nine novel mutations in NR0B1 (DAX1) causing adrenal hypoplasia congenita.

X-linked adrenal hypoplasia congenita (AHC) is caused by mutations in the NR0B1 gene. This gene encodes an orphan member of the nuclear receptor superfamily, DAX1. Ongoing efforts in our laboratory have identified nine novel NR0B1 mutations in X-linked AHC patients (Y81X, 343delG, 457delT, 629delG, L295P, 926-927delTG, 1130delA, 1141-1155del15, and E428X). Two additional families segregate previously identified NR0B1 mutations (501delA and R425T). Sequence analysis of the mitochondrial D-loop indicates that the 501delA family is unrelated through matrilineal descent to our previously analyzed 501delA family.

Developmental expression and activities of specific fos and jun proteins are functionally related to osteoblast maturation: role of Fra-2 and Jun D during differentiation.

Developmental studies of oncogene expression implicate the Fos and Jun family of transcription factors in the regulation of bone growth and differentiation. Promoters of many developmentally regulated genes, including osteocalcin, a marker of osteoblast differentiation, contain AP-1 sites that bind Fos/Jun dimers. Here, we demonstrate that the selective expression of fos- and jun-related genes is functionally related to the stage of osteoblast growth and differentiation in vitro. During osteoblast proliferation, nuclear protein levels of all seven activating protein-1 (AP-1) members are maximal. Subsequently, during the period of extracellular matrix maturation, levels decline. In fully differentiated osteoblasts, Fra-2 and (to a lesser extent) Jun D are the principal AP-1 members detectable by Western blot analysis. AP-1 complex composition and binding activity also exhibit developmental changes. All Fos and Jun family members are involved in AP-1 complex formation in proliferating cells, whereas Fra-2 and Jun D predominate in AP-1 complexes in differentiated osteoblasts. Overexpression of Fos and Jun family members in ROS 17/2.8 cells markedly affects the expression of an osteocalcin promoter-chloramphenicol acetyltransferase construct. Coexpression of only one AP-1 pair, Fra-2 and Jun D, stimulated reporter expression, whereas coexpression of other AP-1 pairs down-regulated expression (i.e. c-jun and any Fos family member) or had no effect (i.e. Fra-1 and Jun B). Promoter deletion analyses indicate that these effects are site specific. Consequential effects of Fra-2 on osteoblast differentiation are further demonstrated by antisense studies in which osteoblast differentiation and the development of a bone tissue-like organization were suppressed. Consistent with recent findings suggesting that AP-1 complex composition can selectively regulate gene transcription, our findings demonstrate that differential expression of Fos and Jun family members could play a role in the developmental regulation of bone-specific gene expression and, as a result, may be functionally significant for osteoblast differentiation.

AP-1 and vitamin D receptor (VDR) signaling pathways converge at the rat osteocalcin VDR element: requirement for the internal activating protein-1 site for vitamin D-mediated trans-activation.

Responsiveness of genes to steroid hormones is a complex process involving synergistic and/or antagonistic interactions between specific receptors and other nonreceptor transcription factors. Thus, DNA recognition elements for steroid hormone receptors are often located among binding sites for other trans-acting factors. The hormonal form of vitamin D, 1,25-dihydroxyvitamin D3, stimulates transcription of the tissue-specific osteocalcin (OC) gene in osteoblastic cells. The rat OC vitamin D response element contains an internal acitvating protein-1 (AP-1) site. Here, we report for the first time that this AP-1 site is critical for the transcriptional enhancement of rat osteocalcin gene expression mediated by vitamin D. Precise mutations were introduced either in the steroid half-elements or in the internal AP-1 sequences. One mutation within the internal AP-1 site retained vitamin D receptor/retinoid X receptor binding equivalent to that of the wild-type sequence, but resulted in complete loss of vitamin D inducibility of the OC promoter. These results suggest a functional interaction between the hormone receptor and nuclear oncoproteins at the rat OC vitamin D response element. This cooperation of activities may have important consequences in physiological regulation of osteocalcin transcription during osteoblast differentiation and bone tissue development in vivo.

Parathyroid hormone stimulates fra-2 expression in osteoblastic cells in vitro and in vivo.

PTH and PTH-related protein (PTHrP) are key mediators of skeletal development and homeostasis through their activation of the PTH-1 receptor. Previous studies have found that several AP-1 family members are regulated by PTH, such as c-fos, fra-1, and c-jun. There are numerous genes in the bone microenvironment that contain AP-1 sites, and different Fos family members are reported to have opposing transcriptional activities at AP-1 sites. The purpose of this study was to identify the effects of PTH on expression of the AP-1 protein complex member, fra-2, to extend our understanding of transcriptional regulators of PTH action. PTH induction of fra-2 messenger RNA (mRNA) levels in MC3T3-E1 preosteoblastic cells was maximal with 0.1 microM PTH (1-34). The expression in vitro was greatest 1 h after treatment and was present with N-terminal PTH but not PTH (7-34) or (53-84). Cycloheximide treatment induced fra-2 expression, and actinomycin D inhibited basal and PTHrP-induced expression. AP-1 protein in nuclear extracts of MC3T3-E1 cells was increased with PTH treatment at 3 h and consisted of high levels of Fra-2 protein, as evidenced by a supershift in an electrophoretic mobility shift assay and Western blot analysis. Up-regulation of steady-state fra-2 mRNA was also noted in vivo, where injection of PTH (1-34) (20 microgram) resulted in a more-than-7-fold maximal increase in fra-2 mRNA expression in the calvaria of mice, after 1 h of treatment. These data add to the transcriptional mediators induced by PTH and suggest that the interplay of AP-1 family members will provide insight into regulatory pathways of PTH and PTHrP for their anabolic and catabolic actions in bone.

Dietary calcium, protein, and phosphorus are related to bone mineral density and content in young women.

BACKGROUND: Dietary factors have been implicated in modifying bone health, although the results remain controversial, particularly in young women. OBJECTIVE: The objective of the study was to determine relations of selected dietary factors and anthropometric measurements to bone mineral density (BMD) of the spine, femoral neck, trochanter, Ward's triangle, radius, and total body and the bone mineral content (BMC) of the spine, radius, and total body. DESIGN: The study was a cross-sectional analysis of 215 women aged 18-31 y. RESULTS: Weight, height, and lean mass were correlated with bone mineral measures at every site (r = 0.17-0.78). Postmenarcheal age (years since onset of menses) was positively correlated with total-body BMD and BMC, radius BMD and BMC, and spine BMC, and negatively correlated with Ward's triangle BMD. Radius BMD was correlated with protein, calcium, and phosphorus intakes, and spine BMD and BMC were correlated with energy, protein, calcium, and phosphorus intakes. These correlations remained significant when postmenarcheal age, lean mass, and fat mass were controlled. A pattern emerged in multiple regression analyses that showed a complex relation among calcium, protein or phosphorus, and the calcium-protein or calcium-phosphorus ratio and spine or total-body BMC and BMD. All 3 variables (calcium, protein or phosphorus, and calcium-protein or calcium-phosphorus ratio) were required in the model for significance. CONCLUSIONS: Anthropometric measures were predictors of bone mass. A single ratio of calcium to phosphorus or protein did not optimize bone mass across the range of calcium intakes.

Exercise and oral contraceptive use suppress the normal age-related increase in bone mass and strength of the femoral neck in women 18-31 years of age.

Women who exercise during their second and third decades may increase their peak bone mass and lower their eventual risk for postmenopausal fracture. However, the effects of exercise in younger women can be modulated by the use of oral contraceptives, which may prevent the normal accretion of bone mass that would otherwise occur. We hypothesized that exercise intervention in young adult women would significantly increase both bone mass and the bending rigidity of the femoral neck. We further hypothesized that exercise intervention in the presence of oral contraceptive use would have a negative effect on bone mass and bending rigidity. Women 18-31 years of age (n = 123) were classified by oral contraceptive use (OC, NOC) and age (18-23, 24-31 years), and then randomized into exercise or nonexercise groups. The exercise protocol consisted of three sessions/week of aerobic and nonaerobic exercises, and continued for 2 years. Each 6 months, the femoral neck of each subject was scanned using a Lunar dual-energy X-ray absorptiometry (DEXA) scanner, and bone mineral content, density and geometric information were used to calculate estimated stresses and bending rigidity at the hip. Percent changes from baseline were analyzed using two-way analysis of variance (ANOVA) at 6, 12, 18, and 24 months. Women who neither exercised nor took oral contraceptives (NE/NOC) had the greatest percentage increases in cross-sectional area (4.98 +/- 2.29%), cross-sectional moment of inertia (9.45 +/- 2.37%), total bone mineral density (2.07 +/- 2.09%), fracture index (8.03 +/- 2.03%), and safety factor (20.03 +/- 5.79%) over the 24 month exercise program. Women who exercised and did not take oral contraceptives (E/NOC) declined on most variables related to femoral strength and bone mass, whereas those women who took oral contraceptives were usually intermediate between NE/NOC and E/NOC, whether they exercised or not. These data show that either exercise or OC use is associated with a suppression of the normal increase in bone mass and mechanical strength in the femoral neck in women 18-31 years old, but the combination of exercise and OC use appears to have a less suppressive effect.

Peak spine and femoral neck bone mass in young women.

Achievement of higher peak bone mass early in life may play a critical role against postmenopausal bone loss. Bone mineral density (BMD) of the spine, femoral neck, greater trochanter, Ward's triangle, and spine bone mineral content (BMC) and bone surface area (BSA) were assessed by dual energy x-ray absorptiometry in 300 healthy females (age 6-32 years). Bone measurements were described by using nonlinear models with age, weight, height, or dietary calcium intake as the explanatory variables. At the spine, femoral neck, greater trochanter, and Ward's triangle, the highest BMD level was observed at 23.0 +/- 1.4, 18.5 +/- 1.6, 14.2 +/- 2.0, and 15.8 +/- 2.1 years, respectively. The age of attaining peak spine BMC and BSA cannot be estimated, as significant increases in these two measures were observed through this age group. Age, weight, and height were all significant predictors of all these bone measurements. Weight was a stronger predictor than age for all sites. Dietary calcium intake was not a significant predictor for any of these bone measurements. We conclude that age of attaining peak bone mass at the hip is younger than at the spine, and BMC and BSA at the spine continue to increase through the early thirties in females.

Newborn screening for phenylketonuria: predictive validity as a function of age.

Data from questionnaires were assembled for 109 infants with phenylketonuria (PKU) and 114 control infants to assess the predictive validity of newborn screening for PKU as a function of age. Patients with PKU had values of less than 4 mg/dL in cord blood and in samples from days 1, 2, and 4 through 7. The proportion of patients with PKU expected to fall below screening cutoffs of 2, 4, and 6 mg/dL was predicted for each age range. Using a cutoff of 4 mg/dL, approximately one third of patients with PKU would be missed by a sample taken from the neonate in the first 12 hours of life, and nearly 10% would be missed with a sample from the second 12 hours of life. This study shows that not all patients with PKU will be detected by newborn screening, and that the phenomenon of early nursery discharges must be considered in developing appropriate screening strategies.

Overo lethal white foal syndrome: equine model of aganglionic megacolon (Hirschsprung disease).

The lethal white foal syndrome (LWFS) is a congenital abnormality of overo spotted horses which is a model for human aganglionic megacolon or Hirschsprung disease. Foals with LWFS have an all white, or nearly all white, coat. They also present clinically with an intestinal obstruction that proves fatal within the first few days of life. The LWFS involves both melanocytes and intestinal ganglion cells, and appears to result from a genetic defect involving neural crest cells. This report describes pathologic studies of two recent cases of LWFS. Two different hypothetical models of inheritance of LWFS are presented and discussed.

Weight gain and longitudinal changes in lung function in steel workers.

Associations among dust exposure, smoking habits, and demographic factors and longitudinal changes of lung function were assessed among male steel workers. Cohort descriptive data analysis was conducted in 541 steel workers who had performed spirometry at least twice between 1982 and 1991 (mean follow-up, 6.1 years). The annual change (slope) in FVC, FEV1, FEV1/FVC%, and in body weight was determined by simple linear regression. The Pearson correlation coefficient between weight change and spirometry changes was calculated. Comparisons were also done in 75 pairs of steel workers matched by age, height, initial FEV1, and smoking status, but whose FEV1 declines differed by > or = 60 mL/yr. The FEV1 and FVC declined an average of 44 and 50 mL/yr, respectively, for the cohort as a whole. The FEV1 and FVC declined 52 and 54 mL/yr for current smokers, 43 and 53 mL/yr for ex-smokers, and 36 and 43 mL/yr for nonsmokers, respectively. Increasing weight was highly correlated with accelerated decline in lung function (p<0.0001). In the matched pairs, mean slopes for FVC, FEV1, and FEV1/FVC ratio were -96 mL/yr, -95 mL/yr, and -0.40%/yr for the rapid decliners; and +5 mL/yr, +10 mL/yr, and +0.10%/yr for their partners (p<0.0001). Matched pair comparisons showed that the rapid decliners averaged a 4.313 kg weight gain, while their partners gained 1.044 kg during the follow-up period. The slope of weight gain was 0.708 kg/yr for rapid decliners and 0.191 kg/yr for comparison workers (p<0.0036). Weight gain, in addition to aging and cigarette smoking, was found to be associated with the longitudinal rate of decline in FVC, FEV1, and FEV1/FVC ratio.

Repeated antenatal glucocorticoid treatment decreases hypothalamic corticotropin releasing hormone mRNA but not corticosteroid receptor mRNA expression in the fetal guinea-pig brain.

Approximately 10% of pregnant women are treated with synthetic glucocorticoids in late gestation, to promote fetal lung maturation. The effectiveness of this treatment has led to the use of repeated dose regimens, with little knowledge of the impact on neuroendocrine development. Animal studies have recently shown that repeated fetal glucocorticoid exposure can lead to permanent changes in hypothalamic-pituitary-adrenal (HPA) function in offspring. In this study, we hypothesized that such treatment modifies corticotropin releasing hormone (CRH), glucocorticoid receptor (GR) and mineralocorticoid receptor (MR) systems in the developing limbic system and hypothalamus. Pregnant guinea-pigs were treated with dexamethasone, betamethasone or vehicle on days 40,41,50,51,60 and 61 of gestation (birth = 68 days). On day 62, guinea-pigs were killed and the fetuses rapidly removed. Glucocorticoid treatment resulted in a dose-dependent reduction in plasma cortisol concentrations in both male and female fetuses. There was also a significant reduction in CRH mRNA expression in the hypothalamic paraventricular nucleus. In contrast, exposure to glucocorticoid increased MR mRNA expression in the hippocampus (CA1/2 and CA3) and dentate gyrus of female fetuses. There was a small but significant increase in GR mRNA expression in limbic structures in male fetuses following treatment with 1 mg/kg dexamethasone. However, there was no significant effect of glucocorticoid exposure on hippocampal GR mRNA expression in female fetuses, or hypothalamic GR mRNA in either males or females. In conclusion, repeated maternal glucocorticoid treatment inhibits fetal HPA function. The fact that CRH mRNA levels were reduced indicates that synthetic glucocorticoids enter the fetal brain. By contrast, fetal glucocorticoid exposure does not downregulate GR mRNA, and increases MR mRNA expression. The latter likely reflects removal of circulating endogenous ligand (cortisol). These alterations may form the basis for permanently modified HPA activity in later life.

Issues in the dietary management of phenylketonuria: breast-feeding and trace-metal nutriture.

We have reviewed our experience with supplemental breast-feeding of the infant with PKU. Our results indicate no harmful nutritional effects of breast-feeding the child with PKU, in comparison with the traditional approach using formula or cow's milk for supplementation. In addition, breast-feeding may provide a source of emotional support for the mother during this difficult period of initial diagnosis and management. It is hoped that this may improve the family's adjustment to this chronic illness. Our work with breast-feeding led us to a consideration of trace-metal nutriture in children treated with these synthetic and semi-synthetic formulas. The results of these investigations suggest that there is a biochemically significant decrease in the bioavailability of zinc when these artificial formulas are used. While no clinical trace-metal deficiency has been described in treated PKU patients, we suggest that these nutritional deficits may relate to subtle abnormalities exhibited by these patients.

Histamine release and circulating cells after antigen inhalation in allergic dogs.

Histamine can be recovered from the blood of ragweed-sensitized dogs after aerosol antigen challenge, although its source is unknown. Neutrophils and eosinophils have been recovered from bronchoalveolar lavage fluid (BALF) obtained under identical conditions. We investigated the time course of changes in histamine levels in plasma and BALF taken from ragweed-sensitized dogs after aerosol challenge. Changes in the numbers of circulating neutrophils, eosinophils, lymphocytes, monocytes, and platelets were also studied. After 3 min, total pulmonary resistance (RL) was maximally increased and systolic blood pressure was maximally decreased. Histamine levels in plasma and BALF were increased and circulating eosinophils and neutrophils were decreased. After 15 min, platelet numbers were reduced. By 90 min, changes in RL, blood pressure, plasma and BALF histamine concentrations, and circulating neutrophils and eosinophils had returned to base-line values, but platelet numbers remained significantly decreased. Sham challenge caused no significant changes in any of these variables. Intravenous administration of histamine in doses large enough to attain plasma levels comparable with those achieved after aerosol antigen challenge resulted in no concomitant rise in BALF histamine levels. We conclude that antigen challenge in sensitized dogs causes increases in BALF and plasma histamine levels and is associated with a reduction in circulating neutrophils, eosinophils, and platelets. It is likely that antigen causes airway mast cells to release mediators that move down a concentration gradient from the airways to the pulmonary circulation.