Krüppel-like factor 4 in transcriptional control of the three unique isoforms of Agouti-related peptide in mice

Agouti-related peptide (AgRP/Agrp) within the hypothalamic arcuate nucleus (ARC) contributes to the control of energy balance, and dysregulated Agrp may contribute to metabolic adaptation during prolonged obesity. In mice, three isoforms of Agrp are encoded via distinct first exons. Agrp-A (ENSMUST00000005849.11) contributed 95% of total Agrp in mouse ARC, whereas Agrp-B (ENSMUST00000194654.2) dominated in placenta (73%). Conditional deletion of Klf4 from Agrp-expressing cells (Klf4Agrp-KO mice) reduced Agrp mRNA and increased energy expenditure but had no effects on food intake or the relative abundance of Agrp isoforms in the ARC. Chronic high-fat diet feeding masked these effects of Klf4 deletion, highlighting the context-dependent contribution of KLF4 to Agrp control. In the GT1-7 mouse hypothalamic cell culture model, which expresses all three isoforms of Agrp (including Agrp-C, ENSMUST00000194091.6), inhibition of extracellular signal-regulated kinase (ERK) simultaneously increased KLF4 binding to the Agrp promoter and stimulated Agrp expression. In addition, siRNA-mediated knockdown of Klf4 reduced expression of Agrp. We conclude that the expression of individual isoforms of Agrp in the mouse is dependent upon cell type and that KLF4 directly promotes the transcription of Agrp via a mechanism that is superseded during obesity.NEW & NOTEWORTHY In mice, three distinct isoforms of Agouti-related peptide are encoded via distinct first exons. In the arcuate nucleus of the hypothalamus, Krüppel-like factor 4 stimulates transcription of the dominant isoform in lean mice, but this mechanism is altered during diet-induced obesity.

Mitochondrial-targeted antioxidant attenuates preeclampsia-like phenotypes induced by syncytiotrophoblast-specific Gαq signaling

Syncytiotrophoblast stress is theorized to drive development of preeclampsia, but its molecular causes and consequences remain largely undefined. Multiple hormones implicated in preeclampsia signal via the Gαq cascade, leading to the hypothesis that excess Gαq signaling within the syncytiotrophoblast may contribute. First, we present data supporting increased Gαq signaling and antioxidant responses within villous and syncytiotrophoblast samples of human preeclamptic placenta. Second, Gαq was activated in mouse placenta using Cre-lox and DREADD methodologies. Syncytiotrophoblast-restricted Gαq activation caused hypertension, kidney damage, proteinuria, elevated circulating proinflammatory factors, decreased placental vascularization, diminished spiral artery diameter, and augmented responses to mitochondrial-derived superoxide. Administration of the mitochondrial-targeted antioxidant Mitoquinone attenuated maternal proteinuria, lowered circulating inflammatory and anti-angiogenic mediators, and maintained placental vascularization. These data demonstrate a causal relationship between syncytiotrophoblast stress and the development of preeclampsia and identify elevated Gαq signaling and mitochondrial reactive oxygen species as a cause of this stress.

Angiotensin AT1A receptor signal switching in Agouti-related peptide neurons mediates metabolic rate adaptation during obesity

Resting metabolic rate (RMR) adaptation occurs during obesity and is hypothesized to contribute to failed weight management. Angiotensin II (Ang-II) type 1 (AT1A) receptors in Agouti-related peptide (AgRP) neurons contribute to the integrative control of RMR, and deletion of AT1A from AgRP neurons causes RMR adaptation. Extracellular patch-clamp recordings identify distinct cellular responses of individual AgRP neurons from lean mice to Ang-II: no response, inhibition via AT1A and Gαi, or stimulation via Ang-II type 2 (AT2) receptors and Gαq. Following diet-induced obesity, a subset of Ang-II/AT1A-inhibited AgRP neurons undergo a spontaneous G-protein "signal switch," whereby AT1A stop inhibiting the cell via Gαi and instead begin stimulating the cell via Gαq. DREADD-mediated activation of Gαi, but not Gαq, in AT1A-expressing AgRP cells stimulates RMR in lean and obese mice. Thus, loss of AT1A-Gαi coupling within the AT1A-expressing AgRP neuron subtype represents a molecular mechanism contributing to RMR adaptation.

Cell-specific transcriptome changes in the hypothalamic arcuate nucleus in a mouse deoxycorticosterone acetate-salt model of hypertension

A common preclinical model of hypertension characterized by low circulating renin is the "deoxycorticosterone acetate (DOCA)-salt" model, which influences blood pressure and metabolism through mechanisms involving the angiotensin II type 1 receptor (AT1R) in the brain. More specifically, AT1R within Agouti-related peptide (AgRP) neurons of the arcuate nucleus of the hypothalamus (ARC) has been implicated in selected effects of DOCA-salt. In addition, microglia have been implicated in the cerebrovascular effects of DOCA-salt and angiotensin II. To characterize DOCA-salt effects upon the transcriptomes of individual cell types within the ARC, we used single-nucleus RNA sequencing (snRNAseq) to examine this region from male C57BL/6J mice that underwent sham or DOCA-salt treatment. Thirty-two unique primary cell type clusters were identified. Sub-clustering of neuropeptide-related clusters resulted in identification of three distinct AgRP subclusters. DOCA-salt treatment caused subtype-specific changes in gene expression patterns associated with AT1R and G protein signaling, neurotransmitter uptake, synapse functions, and hormone secretion. In addition, two primary cell type clusters were identified as resting versus activated microglia, and multiple distinct subtypes of activated microglia were suggested by sub-cluster analysis. While DOCA-salt had no overall effect on total microglial density within the ARC, DOCA-salt appeared to cause a redistribution of the relative abundance of activated microglia subtypes. These data provide novel insights into cell-specific molecular changes occurring within the ARC during DOCA-salt treatment, and prompt increased investigation of the physiological and pathophysiological significance of distinct subtypes of neuronal and glial cell types.

Cardiometabolic Consequences of Deleting the Regulator of G protein Signaling-2 (Rgs2) From Cells Expressing Agouti-Related Peptide or the ANG (Angiotensin) II Type 1A Receptor in Mice

BACKGROUND

RGS (regulator of G protein signaling) family members catalyze the termination of G protein signaling cascades. Single nucleotide polymorphisms in the RGS2 gene in humans have been linked to hypertension, preeclampsia, and anxiety disorders. Mice deficient for Rgs2 (Rgs2Null) exhibit hypertension, anxiety, and altered adipose development and function.

METHODS

To study cell-specific functions of RGS2, a novel gene-targeted mouse harboring a conditional allele for the Rgs2 gene (Rgs2Flox) was developed. These mice were bred with mice expressing Cre-recombinase via the Agouti-related peptide locus (Agrp-Cre) to cause deletion of Rgs2 from all cells expressing Agrp (Rgs2Agrp-KO), or a novel transgenic mouse expressing Cre-recombinase via the ANG (angiotensin) type 1A receptor (Agtr1a/ AT1A) promoter encoded in a bacterial artificial chromosome (BAC-AT1A-Cre) to delete Rgs2 in all Agtr1a-expressing cells (Rgs2AT1A-KO).

RESULTS

Whereas Rgs2Flox, Rgs2Agrp-KO, and BAC-AT1A-Cre mice exhibited normal growth and survival, Rgs2AT1A-KO exhibited pre-weaning lethality. Relative to littermates, Rgs2Agrp-KO exhibited reduced fat gains when maintained on a high fat diet, associated with increased energy expenditure. Similarly, surviving adult Rgs2AT1A-KO mice also exhibited increased energy expenditure. Surprisingly, given the hypertensive phenotype previously reported for Rgs2Null mice and evidence supporting a role for RGS2 in terminating AT1A signaling in various cell types, Rgs2AT1A-KO mice exhibited normal blood pressure, ingestive behaviors, and renal functions, both before and after chronic infusion of ANG (490 ng/kg/min, sc).

CONCLUSIONS

These results demonstrate the development of a novel mouse with conditional expression of Rgs2 and illustrate the role of Rgs2 within selected cell types for cardiometabolic control.

ARRB2 (β-Arrestin-2) Deficiency Alters Fluid Homeostasis and Blood Pressure Regulation

BACKGROUND

GPCRs (G protein-coupled receptors) are implicated in blood pressure (BP) and fluid intake regulation. There is a developing concept that these effects are mediated by both canonical G protein signaling and noncanonical β-arrestin mediated signaling, but the contributions of each remain largely unexplored. Here, we hypothesized that β-arrestin contributes to fluid homeostasis and blood pressure (BP) regulation in deoxycorticosterone acetate (DOCA) salt hypertension, a prototypical model of salt-sensitive hypertension.

METHODS

Global β-arrestin1 (Arrb1) and β-arrestin2 (Arrb2) knockout mice were employed to evaluate drinking behavior, and BP was evaluated in Arrb2-knockout mice. Age- and sex-matched C57BL/6 mice served as controls. We measured intake of water and different sodium chloride solutions and BP employing a 2-bottle choice paradigm with and without DOCA.

RESULTS

Without DOCA (baseline), Arrb2-knockout mice exhibited a significant elevation in saline intake with no change in water intake. With DOCA treatment, Arrb2-knockout mice exhibited a significant increase in both saline and water intake. Although Arrb2-knockout mice exhibited hypernatremia at baseline conditions, we did not find significant changes in total body sodium stores or sodium palatability. In a separate cohort, BP was measured via telemetry in Arrb2-knockout and C57BL/6 mice with and without DOCA. Arrb2-knockout did not exhibit significant differences in BP before DOCA treatment when provided water alone, or when provided a choice of water and saline. However, Arrb2-knockout exhibited an increased pressor response to DOCA-salt.

CONCLUSIONS

These findings suggest that in salt-sensitive hypertension, ARRB2, but not ARRB1 (β-arrestin 1), might counterbalance the canonical signaling of GPCRs.

Chronic intracerebroventricular infusion of angiotensin II causes dose- and sex-dependent effects on intake behaviors and energy homeostasis in C57BL/6J mice

The renin-angiotensin system (RAS) within the brain is implicated in the control of fluid and electrolyte balance, autonomic functions, blood pressure, and energy expenditure. Mouse models are increasingly used to explore these mechanisms; however, sex and dose dependencies of effects elicited by chronic intracerebroventricular (ICV) angiotensin II (ANG II) infusion have not been carefully established in this species. To examine the interactions among sex, body mass, and ICV ANG II on ingestive behaviors and energy balance, young adult C57BL/6J mice of both sexes were studied in a multiplexed metabolic phenotyping system (Promethion) during chronic infusion of ANG II (0, 5, 20, or 50 ng/h). At these infusion rates, ANG II caused accelerating dose-dependent increases in drinking and total energy expenditure in male mice, but female mice exhibited a complex biphasic response with maximum responses at 5 ng/h. Body mass differences did not account for sex-dependent differences in drinking behavior or total energy expenditure. In contrast, resting metabolic rate was similarly increased by ICV ANG II in a dose-dependent manner in both sexes after correction for body mass. We conclude that chronic ICV ANG II stimulates water intake, resting, and total energy expenditure in male C57BL/6J mice following straightforward accelerating dose-dependent kinetics, but female C57BL/6J mice exhibit complex biphasic responses to ICV ANG II. Furthermore, control of resting metabolic rate by ANG II is dissociable from mechanisms controlling fluid intake and total energy expenditure. Future studies of the sex dependency of ANG II within the brain of mice must be designed to carefully consider the biphasic responses that occur in females.

Abstract 114: Metabolic Adaptation During Obesity Is Associated With G Protein Switching By The Angiotensin At1a Receptor In Agrp Neurons

Obesity represents the single greatest impediment to continued improvements in hypertension and cardiovascular disease. Prolonged obesity is associated with “Resting Metabolic Rate (RMR) adaptation” (ie, reduced RMR relative to body composition), and RMR adaptation is proposed to explain resistance to weight loss / weight maintenance after obesity is established. Previously we showed that angiotensin II (ANG) Agtr1a (AT1A) receptors expressed in Agouti-related peptide (AgRP) neurons of the hypothalamic arcuate nucleus (ARC) are required for integrative control of RMR. We hypothesize that changes in AT1A signaling in AgRP cells underlie the development of RMR adaptation. ARC slices from mice expressing tdTomato in AgRP cells ( Agrp -Cre x Ai9) were used for cell-attached voltage clamp recording of AgRP neurons. ANG inhibited ~33% of AgRP neurons via an AT1A-dependent mechanism (deemed a “Type 1i” response, which was inhibitable by losartan (LOS) or genetic deletion of AT1A; Firing rate; aCSF:0.85 ± 0.03 vs ANG:0.20 ± 0.04 vs ANG+LOS:0.91 ± 0.11 Hz, p<0.05) that was also blocked by the Gαi inhibitor, pertussis toxin (PTX), but not by the Gαq inhibitor, BIM-46187 (Δ Firing rate: PTX: -0.39 ± 0.09 Hz, p<0.05 vs BIM: 0.10 ± 0.09 Hz). After 10 weeks of high-fat feeding, roughly half of Type 1 cells exhibited a spontaneous switch from the ANG/AT1A-mediated inhibitory (Type 1i) response to an ANG/AT1A-mediated stimulatory response (“Type 1s”; Firing rate; aCSF: 0.86 ± 0.03 vs ANG:1.10 ± 0.12 vs ANG+LOS:0.82 ± 0.03 Hz, p<0.05), which was blocked by BIM-46187, but not by PTX (Δ Firing rate: PTX: 0.07 ± 0.06 Hz vs BIM: 0.49 ± 0.06 Hz, p<0.05). AAV delivery of Cre-inducible DREADDs into the ARC of lean Agtr1a -Cre mice was then used to study the effects of Gαi vs Gαq signaling in Type 1 AgRP cells upon RMR control. Activation of the Gαi-coupled hM4Di DREADD in AT1A-expressing cells of the ARC was sufficient to increase RMR (+25% from baseline, n=8-10, p<0.05), but activation of a Gαq-coupled DREADD had no effect. We conclude (i) that the AT1A receptor is expressed by a unique subtype of AgRP neuron; (ii) that inhibitory AT1A-Gαi signaling in the Type 1 AgRP cell stimulates RMR; and (iii) that loss of AT1A-Gαi coupling in these cells is sufficient to explain obesity-associated RMR adaptation.

Abstract P040: Angiotensin II Type 1 Receptor Is Expressed In Agouti-related Peptide Neurons Of The Hypothalamic Arcuate Nucleus Within Adult Human Brain

Local paracrine versions of the renin-angiotensin (ANG) system within the brain have been implicated in aspects of cardiovascular and metabolic control, including fluid and electrolyte homeostasis, blood pressure, and energy expenditure, and these effects are often mediated via the ANG type 1 (AT1) receptor. Previous radiographic studies of human brain support ligand binding to AT1 within the hypothalamic arcuate nucleus (ARC), but its localization to individual cell types remains unresolved. Studies of rodent brain demonstrate expression of the rodent AT1 homolog AT1A within the murine ARC almost exclusively within a subset of cells that also express Agouti-related peptide (AgRP) and neuropeptide-Y (NPY). Rodent studies also demonstrate a major role for AT1A within AgRP/NPY neurons in integrative control of energy expenditure, autonomic function, and possibly blood pressure. Thus, we hypothesized that AgRP/NPY neurons of the human ARC would express AT1. ARC sections were obtained after autopsy from a 74 year old male subject diagnosed with Amyotrophic Lateral Sclerosis, body mass index of 34, with self-reported occasional use of over the counter fluticasone propionate, fexofenadine, and topical hydrocortisone. Formalin-fixed, paraffin-embedded ARC was sectioned at 4 microns. RNAscope in situ hybridization methods were used to localize mRNA for AT1 (ACDBio catalog 602841-C2) and AgRP (557451), and nuclei were visualized using DAPI. A similar 4 micron section, obtained within 12 microns of the first section, was analyzed as a negative control (AT1 control: 310043-C2, AgRP control: 310043). As expected, robust expression of AgRP was observed within the ARC (51/106 cells), but not in regions lateral to the ARC (4/114 cells). AT1 expression was observed in cells both within (49/106 cells) and outside the ARC (26/114 cells). Within the ARC, AT1 expression was detected in approximately 40% of AgRP neurons (double-positive n=21, AgRP-only n=30, AT1-only n=28, total cells n=106 in a 95,000 μm 2 region). Only a very small number of signal artifacts (AgRP 0.13; AT1 0.01 % total area) were detected in the negative control. These findings indicate that within the human ARC, and similar to rodents, AT1 is expressed within a unique subset of AgRP/NPY neurons.

Abstract 108: Altered Erk / Klf4-mediated Control Of Agrp And Metabolic Rate During Obesity

Resting metabolic rate (RMR) adaptation contributes to the maintenance of human obesity, yet mechanisms controlling RMR in lean vs obese states remain poorly defined. Leptin contributes to RMR control in part through suppression of inhibitory Agouti-related peptide (AgRP) neurotransmission in the hypothalamic arcuate nucleus (ARC). Within AgRP neurons, leptin activates the extracellular signal-regulated kinase (ERK) cascade, which is thought to interrupt Agrp transcription through interference with the Krüppel-like factor 4 (KLF4) transcription factor, and our published data support altered ARC ERK signaling during obesity. We therefore hypothesized a role for ERK/KLF4 signaling within AgRP neurons for the suppression of AgRP transcription and thereby stimulation of RMR in the lean state, and changes in this pathway during obesity. In the GT1-7 cell model of AgRP neurons, leptin increased the phosphorylated ERK (pERK)/ERK ratio (n=4, 1 uM, 15 min +89% p<0.05) and reduced Agrp mRNA (n=4, 1 uM, 1 hr -43.0% p<0.05); similarly, siRNA knockdown of Klf4 reduced Agrp mRNA (n=4, -21.6% p<0.05). In lean adult C57BL/6J mice, leptin increased the ARC pERK/ERK ratio (n=8, 1 ug/g ip 16.5-fold p<0.05) and stimulated RMR (n=11, 2 ug/g ip 30 min +43.8% p<0.05). Lean transgenic mice with conditional deletion of KLF4 from AgRP neurons ( Agrp -Cre x Klf4 flox ) exhibited increased RMR (n=13 KO +13.48% vs controls n=22 p<0.05). These findings support the model that ERK inhibition of KLF4 within AgRP neurons mechanistically contributes to leptin-mediated control of Agrp and RMR in the lean state. Ten weeks of high fat feeding strongly increases endogenous plasma leptin in C57BL/6J mice, and this treatment increased the ARC pERK/ERK ratio (n=5 +54.4% p<0.05), yet ARC KLF4 was increased (n=6 +74.6% p<0.05) and Agrp mRNA was not suppressed (n=4 +1.6-fold, p=ns). Therefore, these data also support the concept that loss of ERK-mediated suppression of KLF4 within the AgRP neuron during obesity may contribute to the pathogenesis of RMR adaptation.

Melanocortin MC4R receptor is required for energy expenditure but not blood pressure effects of angiotensin II within the mouse brain

The brain renin-angiotensin system (RAS) is implicated in control of blood pressure (BP), fluid intake, and energy expenditure (EE). Angiotensin II (ANG II) within the arcuate nucleus of the hypothalamus contributes to control of resting metabolic rate (RMR) and thereby EE through its actions on Agouti-related peptide (AgRP) neurons, which also contribute to EE control by leptin. First, we determined that although leptin stimulates EE in control littermates, mice with transgenic activation of the brain RAS (sRA) exhibit increased EE and leptin has no additive effect to exaggerate EE in these mice. These findings led us to hypothesize that leptin and ANG II in the brain stimulate EE through a shared mechanism. Because AgRP signaling to the melanocortin MC₄R receptor contributes to the metabolic effects of leptin, we performed a series of studies examining RMR, fluid intake, and BP responses to ANG II in mice rendered deficient for expression of MC₄R via a transcriptional block (Mc4r-TB). These mice were resistant to stimulation of RMR in response to activation of the endogenous brain RAS via chronic deoxycorticosterone acetate (DOCA)-salt treatment, whereas fluid and electrolyte effects remained intact. These mice were also resistant to stimulation of RMR via acute intracerebroventricular (ICV) injection of ANG II, whereas BP responses to ICV ANG II remained intact. Collectively, these data demonstrate that the effects of ANG II within the brain to control RMR and EE are dependent on MC₄R signaling, whereas fluid homeostasis and BP responses are independent of MC₄R signaling.

Cardiometabolic effects of DOCA-salt in male C57BL/6J mice are variably dependent on sodium and nonsodium components of diet

Hypertension characterized by low circulating renin activity accounts for roughly 25%-30% of primary hypertension in humans and can be modeled experimentally via deoxycorticosterone acetate (DOCA)-salt treatment. In this model, phenotypes develop in progressive phases, although the timelines and relative contributions of various mechanisms to phenotype development can be distinct between laboratories. To explore interactions among environmental influences such as diet formulation and dietary sodium (Na) content on phenotype development in the DOCA-salt paradigm, we examined an array of cardiometabolic endpoints in young adult male C57BL/6J mice during sham or DOCA-salt treatments when mice were maintained on several common, commercially available laboratory rodent "chow" diets including PicoLab 5L0D (0.39% Na), Envigo 7913 (0.31% Na), Envigo 2920x (0.15% Na), or a customized version of Envigo 2920x (0.4% Na). Energy balance (weight gain, food intake, digestive efficiency, and energy efficiency), fluid and electrolyte homeostasis (fluid intake, Na intake, fecal Na content, hydration, and fluid compartmentalization), renal functions (urine production rate, glomerular filtration rate, urine Na excretion, renal expression of renin, vasopressin receptors, aquaporin-2 and relationships among markers of vasopressin release, aquaporin-2 shedding, and urine osmolality), and blood pressure, all exhibited changes that were subject to interactions between diet and DOCA-salt. Interestingly, some of these phenotypes, including blood pressure and hydration, were dependent on nonsodium dietary components, as Na-matched diets resulted in distinct phenotype development. These findings provide a broad and robust illustration of an environment × treatment interaction that impacts the use and interpretation of a common rodent model of low-renin hypertension.

Dissociable effects of dietary sodium in early life upon somatic growth, fluid homeostasis, and spatial memory in mice of both sexes

Postnatal growth failure is a common morbidity for preterm infants and is associated with adverse neurodevelopmental outcomes. Although sodium (Na) deficiency early in life impairs somatic growth, its impact on neurocognitive functions has not been extensively studied. We hypothesized that Na deficiency during early life is sufficient to cause growth failure and program neurobehavioral impairments in later life. C57BL/6J mice were placed on low- (0.4), normal- (1.5), or high- (3 g/kg) Na chow at weaning (PD22) and continued on the diet for 3 wk (to PD40). Body composition and fluid distribution were determined serially by time-domain NMR and bioimpedance spectroscopy, and anxiety, learning, and memory were assessed using the elevated plus maze and Morris water maze paradigms in later adulthood (PD63-PD69). During the diet intervention, body mass gains were suppressed in the low- compared with normal- and high-Na groups despite similar caloric uptake rates across groups. Fat mass was reduced in males but not in females fed low-Na diet. Fat-free mass and hydration were significantly reduced in both males and females fed the low-Na diet, although rapidly corrected after return to normal diet. Measures of anxiety-like behavior and learning in adulthood were not affected by diet in either sex, yet memory performance was modified by a complex interaction between sex and early life Na intake. These data support the concepts that Na deficiency impairs growth and that the amount of Na intake which supports optimal somatic growth during early life may be insufficient to fully support neurocognitive development.

Genome Wide Association Study (GWAS) between Attention Deficit Hyperactivity Disorder (ADHD) and Obsessive Compulsive Disorder (OCD)

Objective: The aim of this study was to identify any potential genetic overlap between attention deficit hyperactivity disorder (ADHD) and obsessive compulsive disorder (OCD). We hypothesized that since these disorders share a sub-phenotype, they may share common risk alleles. In this manuscript, we report the overlap found between these two disorders. Methods: A meta-analysis was conducted between ADHD and OCD, and polygenic risk scores (PRS) were calculated for both disorders. In addition, a protein-protein analysis was completed in order to examine the interactions between proteins; p-values for the protein-protein interaction analysis was calculated using permutation. Conclusion: None of the single nucleotide polymorphisms (SNPs) reached genome wide significance and there was little evidence of genetic overlap between ADHD and OCD.

Mycophenolate mofetil: effects on cellular immune subsets, infectious complications, and antimicrobial activity

Mycophenolate mofetil (MMF) is one of the most frequently used immunosuppressive drugs in solid organ transplant recipients. MMF is an inhibitor of inosine-5'-monophosphate, and is able to preferentially inhibit B-cell and T-cell function. The immunosuppressive abilities of MMF have made it one of the most successful anti-rejection drugs in transplant patients, but patients also appear to have increased susceptibility to infections, specifically cytomegalovirus and BK virus. Despite its association with an increased risk of infection, MMF has also exhibited antimicrobial activity against pathogens including hepatitis C, Pneumocystis jirovecii, and human immunodeficiency virus. A thorough understanding of the functions of MMF on the immune system and interaction with infectious pathogens could be helpful in implementing preventative strategies against opportunistic infections in transplant patients.

Vitamin D-deficient rickets: a multifactorial disease

We present a case of an African-American child with vitamin D-deficient rickets. In addition to being solely breast-fed for the period of 1 year, he resided in New England, where exposure to ultraviolet light is limited owing to its northern latitude and long cold winters. He presented with classical signs of nutritional rickets and was immediately responsive to treatment with vitamin D supplementation.

Concave hymenal variations in suspected child sexual abuse victims

The purpose of this study was to describe and analyze the characteristics of, and the clinical correlates to, concave hymenal variations in a large number of suspected child sexual abuse victims. Thirteen hundred eighty-three female child and adolescent suspected sexual abuse victims were comprehensively evaluated. Photocolposcopy was used for the anogenital examinations. Concave hymenal variations were found in 174 patients (12.6%). Sixty-one (35.1%) were anterior. Of these, 40 (65.6%) were curved and smooth, and 21 (34.4%) were angular and/or irregular. One hundred (57.5%) were posterior/lateral. Of these, 33 (33%) were curved and smooth, and 67 (67%) were angular and/or irregular. Thirteen patients (7.5%) had multiple hymenal concavities. Posterior/lateral location was associated with penile-vaginal contact (P = .004), penetration (P = .006), stranger perpetrator (P = .032), hymenal rim narrowing (P less than .001), and posterior fourchette abnormality (P = .049). Angular and/or irregular features were associated with penile contact (P = .005), vaginal contact (P = .035), penile-vaginal contact specifically (P less than .001), penetration (P = .046), abnormal general physical examination (P = .018), and hymenal rim narrowing (P less than .001). Logistic regression analysis demonstrated that age-specific prevalence trends for posterior/lateral (P less than .001) and angular and/or irregular (P = .011) concavities were consistent with acquired anatomic findings. An interobserver exercise with five "blinded" raters evaluating photographs of 49 patients showed significant agreement among observers in sorting posterior/lateral and angular concavities into the diagnostic categories "suggestive of trauma" and "trauma."(ABSTRACT TRUNCATED AT 250 WORDS)

Ecology and Acculturation Among Native Peoples of Central Brazil

Simple exposure to Western goods may not be a sufficient explanation of why isolated village communities increase their participation in external market economies. The degree of market participation by four native villages in central Brazil is related to the difficulty of making a living from slash-and-burn subsistence agriculture as measured by the ratio of labor input to food output.