Circadian clock control of endocrine factors

Organisms experience dramatic fluctuations in demands and stresses over the course of the day. In order to maintain biological processes within physiological boundaries, mechanisms have evolved for anticipation of, and adaptation to, these daily fluctuations. Endocrine factors have an integral role in homeostasis. Not only do circulating levels of various endocrine factors oscillate over the 24 h period, but so too does responsiveness of target tissues to these signals or stimuli. Emerging evidence suggests that these daily endocrine oscillations do not occur solely in response to behavioural fluctuations associated with sleep-wake and feeding-fasting cycles, but are orchestrated by an intrinsic timekeeping mechanism known as the circadian clock. Disruption of circadian clocks by genetic and/or environmental factors seems to precipitate numerous common disorders, including the metabolic syndrome and cancer. Collectively, these observations suggest that strategies designed to realign normal circadian rhythmicities hold potential for the treatment of various endocrine-related disorders.

Characterization of Cre recombinase models for the study of adipose tissue

The study of adipose tissue in vivo has been significantly advanced through the use of genetic mouse models. While the aP2-Cre(BI) and aP2-Cre(Salk) lines have been widely used to target adipose tissue, the specificity of these lines for adipocytes has recently been questioned. Here we characterize Cre recombinase activity in multiple cell populations of the major adipose tissue depots of these and other Cre lines using the membrane-Tomato/membrane-GFP (mT/mG) dual fluorescent reporter. We find that the aP2-Cre(BI) and aP2-Cre(Salk) lines lack specificity for adipocytes within adipose tissue, and that the aP2-Cre(BI) line does not efficiently target adipocytes in white adipose depots. Alternatively, the Adiponectin-CreERT line shows high efficiency and specificity for adipocytes, while the PdgfRα-CreERUCL and PdgfRα-CreERJHU lines do not efficiently target adipocyte precursor cells in the major adipose depots. Instead, we show that the PdgfRα-Cre line is preferable for studies targeting adipocyte precursor cells in vivo.

Subacute cutaneous lupus erythematosus presenting in childhood: a case report and review of the literature

A 2-year-old African American, Hispanic boy presented with well-defined, violaceous, annular dermal plaques without scale over the upper extremities, face, lower extremities, and buttocks. The clinical presentation and laboratory studies were consistent with a diagnosis of subacute cutaneous lupus erythematous (SCLE). SCLE presenting in childhood is exceedingly rare, with only eight cases previously reported. It is important to clinically differentiate SCLE from other eruptions more common to children, such as atopic dermatitis, urticarial drug eruptions, and psoriasis vulgaris, because progression to systemic lupus erythematous (SLE) may occur. SLE needs to be closely followed. We present the first case (to our knowledge) of SCLE in a child of African American or Hispanic descent and provide a table of other documented pediatric presentations of SCLE for comparison.

Effects of low-dose metformin and rosiglitazone on biochemical, clinical, metabolic and biophysical outcomes in polycystic ovary syndrome

The aim of this study was to compare the effect of low-dose metformin and rosiglitazone on clinical, biochemical, ultrasound features and endothelial function in patients with polycystic ovary syndrome (PCOS). After randomisation, a group of 17 women received metformin 500 mg b.d. (MG) and a group of 18 received rosiglitazone 4 mg o.d. (RG) for 3 months. Serum FSH, LH, testosterone, fasting glucose, insulin, IGF-1, IGFBP-3, CRP were measured at baseline and follow-up. Ovarian scan and microcirculation studies were also performed. It was found that there was a reduction in hyperandrogenaemia, insulin resistance, lipidaemia, CRP levels, ovarian volume and number of follicles in both groups. No improvement in endothelial- dependent function was noted but a significant improvement in endothelial-independent function in rosiglitazone group. It was concluded that low-dose therapeutic regimen with rosiglitazone and metformin, has comparable beneficial impacts on metabolic, hormonal and morphological features of PCOS but no obvious effect on vascular parameters in a population of predominantly mild PCOS.

Weighing in on adipocyte precursors

Obesity, defined as an excessive increase in white adipose tissue (WAT), is a global health epidemic. In obesity, WAT expands by increased adipocyte size (hypertrophy) and number (hyperplasia). The location and cellular mechanisms of WAT expansion greatly affect the pathogenesis of obesity. However, the cellular and molecular mechanisms regulating adipocyte size, number, and depot-dependent expansion in vivo remain largely unknown. This perspective summarizes previous work addressing adipocyte number in development and obesity and discusses recent advances in the methodologies, genetic tools, and characterization of in vivo adipocyte precursor cells allowing for directed study of hyperplastic WAT growth in vivo.

Use of osmium tetroxide staining with microcomputerized tomography to visualize and quantify bone marrow adipose tissue in vivo

Adipocytes reside in discrete, well-defined depots throughout the body. In addition to mature adipocytes, white adipose tissue depots are composed of many cell types, including macrophages, endothelial cells, fibroblasts, and stromal cells, which together are referred to as the stromal vascular fraction (SVF). The SVF also contains adipocyte progenitors that give rise to mature adipocytes in those depots. Marrow adipose tissue (MAT) or marrow fat has long been known to be present in bone marrow (BM) but its origin, development, and function remain largely unknown. Clinically, increased MAT is associated with age, metabolic diseases, drug treatment, and marrow recovery in children receiving radiation and chemotherapy. In contrast to the other depots, MAT is unevenly distributed in the BM of long bones. Conventional quantitation relies on sectioning of the bone to overcome issues with distribution but is time-consuming, resource intensive, inconsistent between laboratories and may be unreliable as it may miss changes in MAT volume. Thus, the inability to quantitate MAT in a rapid, systematic, and reproducible manner has hampered a full understanding of its development and function. In this chapter, we describe a new technique that couples histochemical staining of lipid using osmium tetroxide with microcomputerized tomography to visualize and quantitate MAT within the medullary canal in three dimensions. Imaging of osmium staining provides a high-resolution map of existing and developing MAT in the BM. Because this method is simple, reproducible, and quantitative, we expect it will become a useful tool for the precise characterization of MAT.

Isolation and study of adipocyte precursors

White adipose tissue (WAT) is a heterogeneous tissue composed of lipid-filled adipocytes and several nonadipocyte cell populations, including endothelial, blood, uncharacterized stromal, and adipocyte precursor cells. Although lipid-filled adipocytes account for the majority of WAT volume and mass, nonadipocyte cell populations have critical roles in WAT maintenance, growth, and function. As mature adipocytes are terminally differentiated postmitotic cells, differentiation of adipocyte precursors is required for hyperplastic WAT growth during development and in obesity. In this chapter, we present methods to separate adipocyte precursor cells from other nonadipocyte cell populations within WAT for analysis by flow cytometry or purification by fluorescence-activated cell sorting. Additionally, we provide methods to study the adipogenic capacity of purified adipocyte precursor cells ex vivo.

Determination of mesenchymal stem cell fate by pigment epithelium-derived factor (PEDF) results in increased adiposity and reduced bone mineral content

Pigment epithelium-derived factor (PEDF), the protein product of the SERPINF1 gene, has been linked to distinct diseases involving adipose or bone tissue, the metabolic syndrome, and osteogenesis imperfecta (OI) type VI. Since mesenchymal stem cell (MSC) differentiation into adipocytes vs. osteoblasts can be regulated by specific factors, PEDF-directed dependency of murine and human MSCs was assessed. PEDF inhibited adipogenesis and promoted osteoblast differentiation of murine MSCs, osteoblast precursors, and human MSCs. Blockade of adipogenesis by PEDF suppressed peroxisome proliferator-activated receptor-γ (PPARγ), adiponectin, and other adipocyte markers by nearly 90% compared with control-treated cells (P<0.001). Differentiation to osteoblasts by PEDF resulted in a common pathway that involved PPARγ suppression (P<0.01). Canonical Wnt-β-catenin signaling results in a MSC differentiation pattern analogous to that seen with PEDF. Thus, adding PEDF enhanced Wnt-β-catenin signal transduction in human MSCs, demonstrating a novel Wnt agonist function. In PEDF knockout (KO) mice, total body adiposity was increased by >50% compared with controls, illustrating its systemic role as a negative regulator of adipogenesis. Bones from KO mice demonstrated a reduction in mineral content recapitulating the OI type VI phenotype. These results demonstrate that the human diseases associated with PEDF reflect its ability to modulate MSC differentiation.

Variation in cortical density within the cortical shell of individuals across a range in densities and ages

OBJECTIVES

The purpose of this study was to determine variability in cortical volumetric bone density (vBMD) from a single slice tibia image over a range of vBMD readings and ages.

METHODS

Males and females (N=80; aged 6-80) were randomly selected from a previous study. Cortical vBMD at the anterior, posterior, medial, and lateral regions as well as the endocortical, mid-cortical, and pericortical regions of the cortical shell were determined using pQCT.

RESULTS

Mean anterior ROI cortical vBMD (1111±11 mg/cm(3)) was lower than the posterior and lateral ROIs (1169±7 mg/cm(3) and 1151±9 mg/cm(3), respectively), (p<0.05). Individuals with lower overall cortical vBMD and younger individuals had greater vBMD variability within the shell (r=0.37, p=0.004). Difference between anterior and posterior regions was inversely associated with cortical vBMD and jump power (r=0.46, p=0.001). Endocortical vBMD (1080±6 mg/cm) was lower than the mid-cortical and pericortical regions (1152±5 mg/cm(3) and 1147±5 mg/cm, respectively).

CONCLUSIONS

Variability in cortical vBMD was higher among young individuals and those with lower overall cortical vBMD, while lowest in older individuals and men. The anterior ROI had lower mean cortical vBMD than posterior or lateral regions, and endocortical vBMD was lower than the mid- and pericortical regions.

Characterization of the adipocyte cellular lineage in vivo

Mature adipocytes are generated through the proliferation and differentiation of precursor cells. Our prior studies identified adipocyte progenitors in white adipose tissue (WAT) as Lin−:CD29+:CD34+:Sca-1+:CD24+ (CD24+) cells that are capable of generating functional WAT¹. Here, we employ several Cre recombinase mouse models to identify the adipocyte cellular lineage in vivo. While it has been proposed that white adipocytes are derived from endothelial² and hematopoietic^{3, 4} lineages, we find that neither of these lineages label white adipocytes. However, platelet-derived growth factor receptor α (PdgfRα)-Cre trace labels all white adipocytes. Analysis of WAT from PdgfRα-Cre reporter mice identifies CD24+ and Lin−:CD29+:CD34+:Sca-1+:CD24− (CD24−) cells as adipocyte precursors. We show that CD24+ cells generate the CD24− population in vivo and the CD24− cells express late markers of adipogenesis. From these data we propose a model where the CD24+ adipocyte progenitors become further committed to the adipocyte lineage as CD24 expression is lost, generating CD24− preadipocytes. This characterization of the adipocyte cellular lineage will facilitate study of the mechanisms that regulate WAT formation in vivo and WAT mass expansion in obesity.

Presternal dermoid cyst mimicking lymphatic malformation: a case report and review of the literature

We describe an 11-month-old boy with an unusually large presternal mass present since birth. The large size, fluctuant properties, transillumination, compressibility, and imaging of this lesion were characteristic of a lymphatic malformation. Although four treatments with sclerotherapy markedly reduced its size, it was not until definitive treatment with surgical excision and the final pathology report that we arrived at the ultimate diagnosis of dermoid cyst. Dermoid cysts, although appearing along embryologic lines of closure, are rarely presternal. They are usually small, thick walled, and filled with sebaceous or keratinous fluid, which typically allows for clinical diagnosis, and show characteristic features on magnetic resonance imaging (MRI) and ultrasound. However, this case illustrates that dermoid cysts can appear in somewhat atypical locations, and imaging is not always diagnostic, so dermoid cyst should remain a part of the differential diagnosis for any lesion presenting midsternally, regardless of the size and imaging characteristics.

Post-traumatic pelvic extramedullary haemopoetic tissue causing lower urinary tract symptoms

Extramedullary haemopoiesis (EMH) is the abnormal development and growth of haemopoietic tissue outside the bone marrow. It is usually asymptomatic and occurs in the presence of myelodysplastic syndromes. In this report, we describe the first post-traumatic EMH presenting with lower urinary tract symptoms.

Analysis of gene networks in white adipose tissue development reveals a role for ETS2 in adipogenesis

Obesity is characterized by an expansion of white adipose tissue mass that results from an increase in the size and the number of adipocytes. However, the mechanisms responsible for the formation of adipocytes during development and the molecular mechanisms regulating their increase and maintenance in adulthood are poorly understood. Here, we report the use of leptin-luciferase BAC transgenic mice to track white adipose tissue (WAT) development and guide the isolation and molecular characterization of adipocytes during development using DNA microarrays. These data reveal distinct transcriptional programs that are regulated during murine WAT development in vivo. By using a de novo cis-regulatory motif discovery tool (FIRE), we identify two early gene clusters whose promoters show significant enrichment for NRF2/ETS transcription factor binding sites. We further demonstrate that Ets transcription factors, but not Nrf2, are regulated during early adipogenesis and that Ets2 is essential for the normal progression of the adipocyte differentiation program in vitro. These data identify ETS2 as a functionally important transcription factor in adipogenesis and its possible role in regulating adipose tissue mass in adults can now be tested. Our approach also provides the basis for elucidating the function of other gene networks during WAT development in vivo. Finally these data confirm that although gene expression during adipogenesis in vitro recapitulates many of the patterns of gene expression in vivo, there are additional developmental transitions in pre and post-natal adipose tissue that are not evident in cell culture systems.

Adipocyte lineage cells contribute to the skin stem cell niche to drive hair cycling

In mammalian skin, multiple types of resident cells are required to create a functional tissue and support tissue homeostasis and regeneration. The cells that compose the epithelial stem cell niche for skin homeostasis and regeneration are not well defined. Here, we identify adipose precursor cells within the skin and demonstrate that their dynamic regeneration parallels the activation of skin stem cells. Functional analysis of adipocyte lineage cells in mice with defects in adipogenesis and in transplantation experiments revealed that intradermal adipocyte lineage cells are necessary and sufficient to drive follicular stem cell activation. Furthermore, we implicate PDGF expression by immature adipocyte cells in the regulation of follicular stem cell activity. These data highlight adipogenic cells as skin niche cells that positively regulate skin stem cell activity, and suggest that adipocyte lineage cells may alter epithelial stem cell function clinically.

Methods for measurement of pediatric bone

Many experts believe that optimizing bone mineral accrual early in life may prevent childhood fractures and possibly delay the development of osteoporosis later in life. Adequate nutrition and physical activity are environmental factors important in determining whether or not children acquire an appropriate amount of bone for their body size. Pediatric diseases, or therapeutic interventions used in their treatment, may interfere with normal bone development. Although there are specific methods available for assessing pediatric bone, there is no one method that can adequately assess bone health and identify the specific bone deficits that may be occurring. Understanding the biological basis for bone deficits and the ability of various bone assessment methods to discriminate or measure these deficits is important in understanding normal bone development and how to prevent and treat pediatric bone disease. The purpose of this review is to briefly describe changes in bone with growth, to define "bone density" in biological terms, to discuss some of the issues with pediatric bone measurements, and to review the three main methods for assessing bone parameters in pediatric populations. These methods, including dual energy X-ray absorptiometry (DXA), quantitative ultrasound (QUS) and peripheral quantitative computed tomography (pQCT) will be described, the advantages and disadvantages discussed, and the relationship between bone parameters and fracture risk presented for each of the methods.

Capsaicin exposure elicits complex airway defensive motor patterns in normal humans in a concentration-dependent manner

The airway defensive response to tussive agents, such as capsaicin, is frequently assessed by counting the number of cough sounds, or expulsive events. This method does not identify or differentiate important respiratory events that occur in the respiratory muscles and lungs, which are critical in assessing airway defensive responses. The purpose of this study was to characterize the airway defensive behaviours (cough and expiration reflex) to capsaicin exposure in humans. We observed complex motor behaviours in response to capsaicin exposure. These behaviours were defined as cough reacceleration (CRn) and expiration reflex (ERn), where n is the number of expulsive events with and without a preceding inspiratory phase, respectively. Airway defensive responses were defined in terms of frequency (number of expulsive events), strength (activation of abdominal muscles) and behaviour type (CRn vs. ERn). Thirty-six subjects (15 females, 24+/-4 yr) were instrumented with EMG electrodes placed over the rectus abdominis (RA), external abdominal oblique (EO) and the 8th intercostal space (IC8). A custom-designed mouth pneumotachograph was used to assess the airflow acceleration, plateau velocity and phase duration of the expulsive phase. Subjects inhaled seven concentrations of capsaicin (5-200 microM) in a randomized block order. The total number of expulsive events (frequency) and the sum of integrated EMG for the IC8, RA and EO (strength) increased in a curvilinear fashion. Differentiating the airway defense responses into type demonstrated predominately CR1 and CR2 (i.e. inspiration followed by one and two expulsive events, respectively) with very few ER's at <50 microM capsaicin. At higher concentrations (>50 microM) ER's with one or more expulsive events (ER1) appeared, and the number of CR's with three or more expulsive events (CR3) increased. The decrease in EMG activation and airflow measurements with each successive expulsive event suggests a decline in power and shear force as the number of expulsive events increased. Therefore, the airway defensive response to capsaicin is a complex motor pattern that functions to coordinate ER's and CR's with differing numbers of expulsive events possibly to prevent aspirations and keep air moving to promote clearance.

Kidney failure associated with liver transplantation or liver failure: the impact of continuous veno-venous hemofiltration

BACKGROUND AND AIMS

The short-term outcome of critically ill patients with kidney failure combined with severe liver failure or orthotopic liver transplantation (OLTx) is poor. We sought to test the hypothesis that, with the exclusive use of continuous veno-venous hemofilration (CVVH) with minimal heparin-anticoagulation, the short and long-term outcomes of these patients would be improved.

PATIENTS

Sixty-six consecutive patients with combined liver and kidney failure

SETTING

Intensive Care Unit of tertiary hospital

DESIGN

Retrospective interrogation of prospectively collected databases

INTERVENTION

Treatment of all patients with continuous veno-venous hemofiltration (CVVH) by protocol with 2L/h of ultrafiltration rate and minimal use of circuit heparinization. Retrieval of specific information on demographic, clinical, therapeutic and outcome details.

MEASUREMENTS AND MAIN RESULTS

From July 1995 to April 2004, 66 patients with combined liver and renal failure received continuous veno-venous hemofiltration (CVVH). Of these, 26 received liver transplantation and 40 did not. There were no significant differences in age, APACHE II score, bilirubin, ALT, INR or albumin on admission. The average duration of CVVH was 9.5 days for OLTx patients and 5 days for non-transplanted patients (p=0.013). Heparin anticoagulation was used in only 12% of OLTx patients and 20% of non-transplanted patients. ICU mortality was 15% in OLTx patients and 63% in non-transplanted patients (p<0.0005); hospital mortality was 23% compared to 70% (p<0. 001). Mean survival time at follow up was 1,120 days compared to 358 days (p<0.0001).

CONCLUSIONS

ARF associated with OLTx has a much better outcome than ARF without OLTx. Furthermore, management based on a conservative anticoagulation policy and CVVH as the exclusive form of renal support was associated with the best ICU, hospital and long term survival reported so far.