Kerby C. Oberg

Regulation of glomerular basement membrane collagen expression by LMX1B contributes to renal disease in nail patella syndrome

Basement membrane (BM) morphogenesis is critical for normal kidney function. Heterotrimeric type IV collagen, composed of different combinations of six α-chains (1–6), is a major matrix component of all BMs (ref. 2). Unlike in other BMs, glomerular BM (GBM) contains primarily the α3(IV) and α4(IV) chains, together with the α5(IV) chain. A poorly understood, coordinated temporal and spatial switch in gene expression from ubiquitously expressed α1(IV) and α2(IV) collagen to the α3(IV), α4(IV) and α5(IV) chains occurs during normal embryogenesis of GBM (ref. 4). Structural abnormalities of type IV collagen have been associated with diverse biological processes including defects in molecular filtration in Alport syndrome, cell differentiation in hereditary leiomyomatosis, and autoimmunity in Goodpasture syndrome; however, the transcriptional and developmental regulation of type IV collagen expression is unknown. Nail patella syndrome (NPS) is caused by mutations in LMX1B, encoding a LIM homeodomain transcription factor. Some patients have nephrosis-associated renal disease characterized by typical ultrastructural abnormalities of GBM (refs. 8,9). In Lmx1b−/− mice, expression of both α(3)IV and α(4)IV collagen is strongly diminished in GBM, whereas that of α1, α2 and α5(IV) collagen is unchanged. Moreover, LMX1B binds specifically to a putative enhancer sequence in intron 1 of both mouse and human COL4A4 and upregulates reporter constructs containing this enhancer-like sequence. These data indicate that LMX1B directly regulates the coordinated expression of α3(IV) and α4(IV) collagen required for normal GBM morphogenesis and that its dysregulation in GBM contributes to the renal pathology and nephrosis in NPS.

The Effect of AlloDerm Envelopes on Periprosthetic Capsule Formation with and without Radiation

Background: The pathobiology of radiation-induced periprosthetic capsular formation and factors that may ameliorate its development have not been fully elucidated. The authors hypothesized that AlloDerm would diminish radiation-induced capsular formation. Methods: Two 5-ml implants were placed submuscularly in the backs of 41 rats. The right implant was wrapped with AlloDerm and the left remained bare. After 48 hours, 20 animals underwent irradiation to each implant, and 21 animals underwent no further treatment and served as controls. After 3 and 12 weeks, the capsules were harvested and submitted for tensile strength and histologic examination. Intraprosthetic pressures were measured in each implant at the time of surgery and when the animals were killed. Results: The intraprosthetic pressure decrease was uniform among all groups at 3 and 12 weeks. Between 3 and 12 weeks, capsular tensile strength increased in nonirradiated bare implants. There was considerable invasion of nonirradiated AlloDerm by inflammatory infiltrates at 3 weeks, and AlloDerm thickness decreased over time. Cellular invasion of AlloDerm was decreased with irradiation at both time points. Capsular tensile strength and thickness of the irradiated bare and AlloDerm capsules did not change between 3 and 12 weeks. Radiation increased inflammation of bare capsules at 12 weeks, but it was significantly reduced in irradiated AlloDerm capsules. The majority of irradiated bare capsules developed pseudoepithelium, whereas AlloDerm protected capsules from this transformation. Conclusion: AlloDerm decreases radiation-related inflammation and delays or diminishes pseudoepithelium formation and thus may slow progression of capsular formation, fibrosis, and contraction.

Iron, copper, and iron regulatory protein 2 in Alzheimer’s disease and related dementias

Accumulating evidence implicates a role for altered iron and copper metabolism in the pathogenesis of neurodegenerative disorders such as Alzheimers disease (AD). However, imbalances in the levels of the various forms of iron at different stages of AD have not been examined. In this pilot study we extracted and measured the levels of loosely bound, non-heme and total iron and copper in the frontal cortex and hippocampus of patients with mild-moderate AD (n=3), severe AD (n=8) and dementia with Lewy bodies (DLB, n=6), using graphite furnace atomic absorption spectrometry (GFAAS). Additionally, the expression of iron regulatory protein 2 (IRP2) was examined in relation to the pathological hallmarks of AD and DLB, amyloid plaques, neurofibrillary tangles (NFT), and Lewy bodies, by immunohistochemistry. We found significantly decreased loosely bound iron in the hippocampal white matter of mild-moderate and severe AD patients and a trend towards increased non-heme iron in the hippocampal gray matter of severe AD patients. Furthermore, decreased levels of total copper were seen in severe AD and DLB frontal cortex compared to controls, suggesting an imbalance in brain metal levels in both AD and DLB. The decrease in loosely bound iron in mild-moderate AD patients may be associated with myelin breakdown seen in the beginning stages of AD and implicates that iron dysregulation is an early event in AD pathogenesis.

Gene Expression Patterns in the Hypoxic Murine Placenta: A Role in Epigenesis?

Hypoxia has been identified as a major stress or in placental and fetal development. To test the hypothesis that hypoxic stress responses are associated with gene expression changes, the authors measured gene expression in the mouse placenta in response to 48 hours of hypoxia. Embryonic day 15.5 pregnant mice were exposed to 48 hours of hypoxia (10.5% O2), after which the Affymetrix Mouse 430A_2.0 array was used to measure gene expression changes in the placenta. The authors observed 171 probe sets, corresponding to 163 genes, that were regulated by hypoxia (P < .01). Ninety genes were upregulated, and 73 were downregulated. The authors functionally annotated the regulated genes and examined overrepresented functional categories. Among the upregulated and downregulated genes, several overrepresented functional categories were observed. Upregulated genes included those involved in metabolism, oxygen transport, proteolysis, cell death, metabolism of reactive oxygen species, and DNA methylation. Genes involved in transcription, cell cycle regulation, and cell structure were downregulated. Microarray analysis has allowed the description of the genetic responses to hypoxia in the mouse placenta. The observation that hypoxia upregulates reactive oxygen species metabolism, in conjunction with DNA methylation enzymes, suggests that hypoxia may contribute to long-term epigenetic changes in stressed fetal tissues and organs.

Classification of Congenital Anomalies of the Hand and Upper Limb: Development and Assessment of a New System

The Oberg, Manske, and Tonkin (OMT) classification of congenital hand and upper limb anomalies was proposed in 2010 as a replacement for the Swanson International Federation of Societies for Surgery of the Hand classification system, which has been the accepted system of classification for the international surgical community since 1976. The OMT system separates malformations from deformations and dysplasias. Malformations are subdivided according to the axis of formation and differentiation that is primarily affected and whether the anomalies involve the whole limb or the hand plate. This review outlines the development of classification systems and explores the difficulty of incorporating our current knowledge of limb embryogenesis at a molecular level into current systems. An assessment of the efficacy of the OMT classification demonstrates acceptable inter- and intraobserver reliability. A prospective review of 101 patients confirms that all diagnoses could be classified within the OMT system. Consensus expert opinion allowed classification of those conditions for which there is not a clear understanding of the mechanism of dysmorphology. A refined and expanded OMT classification is presented.

The effectiveness and safety of topical PhotoActif phosphatidylcholine-based anti-cellulite gel and LED (red and near-infrared) light on Grade II-III thigh cellulite: a randomized, double-blinded study.

Background: Cellulite of the upper lateral and posterior thighs and lower buttocks represents a common, physiological and unwanted condition whose etiologies and effective management are subjects of continued debate. Objective: The purpose of this controlled, double‐blinded study is to evaluate the efficacy and safety of a novel phosphatidylcholine‐based, cosmeceutical anti‐cellulite gel combined with a light‐emitting diode (LED) array at the wavelengths of red (660 nm) and near‐infrared (950 nm), designed to counter the possible mechanisms that purportedly accentuate the presence of thigh cellulite. Methods: Nine healthy female volunteers with Grade II–III thigh cellulite were randomly treated twice daily with an active gel on one thigh and a placebo gel on the control thigh for 3 months. Twice weekly, each thigh was exposed for a 15‐minute treatment with LED light for a total of 24 treatments. At 0, 6, and 12 weeks of the study the following clinical determinants were obtained: standardized digital photography, height and weight measurements, standardized thigh circumference tape measurements, pinch testing, body mass index (kg/m2), body fat analysis (Futrex‐5500/XL near‐infrared analyzer), and digital high‐resolution ultrasound imaging of the dermal–adiposal border. In selected patients, full‐thickness biopsies of the placebo and active‐treated sites were obtained. At 18 months, repeat standardized digital photography, height and weight measurements, and body mass index measurements were obtained. Results: At the end of 3 months, eight of nine thighs treated with the phosphatidylcholine‐based, anti‐cellulite gel and LED treatments were downgraded to a lower cellulite grade by clinical examination, digital photography, and pinch test assessment. Digital ultrasound at the dermal‐adiposal interface demonstrated not only a statistically significant reduction of immediate hypodermal depth, but also less echo‐like intrusions into the dermal layer. Three of six biopsies from thighs treated for 3 months with the active gel and LED treatments demonstrated less intrusion of subcutaneous fat into the papillary and reticular dermis. In nine placebo and LED‐treated thighs and one of the actively treated thighs, minimal clinical changes were observed or measured by the clinical determinants throughout the 3‐month study. At the month‐18 evaluation period for the eight responsive thighs, five thighs reverted back to their original cellulite grading, while three thighs continued to maintain their improved status. Patients experienced minimal and transient side effects that included puritus, erythema and swelling. Conclusions: The results of this small but well‐documented, randomized, double‐blinded study affirms that eight of nine thighs with Grade II–III cellulite responded positively to a novel, combined 3‐month treatment program of a phosphatidylcholine‐based, anti‐cellulite gel and LED exposure, as determined by the clinical determinants obtained. Patients experienced minimal and transient side effects. At the month‐18 evaluation period (15 months after treatment), five responsive thighs reverted back to their original cellulite grading, indicating a need for maintenance treatment. Future studies are needed to verify these tentative positive observations.

Classification and developmental biology of congenital anomalies of the hand and upper extremity.

Congenital anomalies of the hand and upper extremity are classified according to appearance; thus, the myriad of disparate presentations are organized into groups that share common morphologic features. The primary purpose of a classification is to enhance communication about the specific features of a condition by providing a descriptive framework for clinicians. Therefore, classification schemes should reflect the full spectrum of morphologic abnormalities within a given condition, and should be uncomplicated and easy for clinicians to remember and use. While an ideal classification would also guide treatment, provide insight into prognosis, and incorporate the etiologic mechanism of the condition, congenital classification systems often fall short of these goals. The embryological development of the upper limb proceeds along three axes: proximal-distal, anterior-posterior (referred to postnatally as radial-ulnar by clinicians, because the fetal upper limb rotates during development), and dorsal-ventral1. The apical ectodermal ridge and the underlying mesoderm control proximal-distal development through a reciprocal loop of fibroblast growth factors and Wnt proteins2. The zone of polarizing activity located in the posterior (ulnar) limb mesoderm expands and posteriorizes the limb along the anterior-posterior (radial-ulnar) axis through a secreted morphogen, sonic hedgehog (SHH)3. The apical ectodermal ridge and the zone of polarizing activity are closely linked by a reciprocal feedback loop that maintains SHH expression at the posterior (ulnar)-distal border of the apical ectodermal ridge during progressive outgrowth. Dorsal ectoderm controls limb dorsalization through the secretion of Wnt7a and the induction of Lmx1b in the underlying dorsal mesoderm4. A reciprocal feedback loop between Wnt7a and SHH has also been demonstrated5. Thus, the integration of SHH into the pathways that control proximal-distal, anterior-posterior, and dorsal-ventral axes ensures coordinated patterning during each phase of limb outgrowth and development (i.e., humerus, forearm, and hand). Targeted disruption of …

Surgical treatment of congenital syndactyly of the hand.

Abstract Syndactyly is a congenital anomaly of the hand that is more common in males, is present bilaterally in 50% of affected patients, and often is associated with other musculoskeletal malformations or systemic syndromes. The goal of syndactyly release is to create a functional hand with the fewest surgical procedures while minimizing complications. For simple syndactyly, surgical reconstruction can begin at approximately 6 months, although many surgeons prefer to wait until the infant is 18 months old. Special situations, such as complex syndactyly and involvement of border digits, may warrant surgical intervention earlier than 6 months. Reconstruction of the web commissure is the most technically challenging part of the operation, followed by separation of the remaining digits. Full‐thickness skin grafting is almost always required for soft‐tissue coverage. Complex syndactyly and syndactyly associated with other hand anomalies warrant special consideration. After reconstruction, patients should be examined periodically until they have achieved skeletal maturity because late complications such as web creep can occur.

Renal Tubular Dysgenesis in Twin-Twin Transfusion Syndrome

ABSTRACT In twin-twin transfusion syndrome (TTTS), the disparity in circulation is reflected in discordant fetal growth, urine output, and amniotic fluid accumulation. The effect of uneven shunting of the growth factor and nutrient-rich vasculature on development and differentiation of the kidney has not been well studied. We analyzed renal tubular growth and differentiation in 25 fetal autopsies with TTTS (13 donors and 12 recipients, including 9 sibling pairs) between 18 and 33 weeks gestation. Immunohistochemical markers for fumarylacetoacetate hydrolase (FAH), Leu-M1, and Lotus tetragonolobus (LTA) were used to identify proximal convoluted tubules, and epithelial membrane antigen (EMA) was used to demonstrate distal convoluted and collecting tubules. FAH appeared to be more specific and reliable than either Leu-M1 or LTA in the identification of proximal tubules. Donors tended to demonstrate a paucity of proximal tubules with crowding of glomeruli characteristic of renal tubular dysgenesis (RTD). The degree of dysgenesis was greater in later gestations and associated with more severe growth restriction. Donors in TTTS are at risk for the development of RTD. Several authors suggest ischemia as the underlying cause of “acquired” RTD. However, in this setting there is no evidence of cell death or necrosis, and we suggest that hypoperfusion leading to decreased glomerular filtration is the underlying etiology, with the severity of RTD related to the degree of shunting.

Busulfan-induced central polydactyly, syndactyly and cleft hand or foot: A common mechanism of disruption leads to divergent phenotypes

The prevalence of clinical phenotypes that exhibit combinations of central polydactyly, syndactyly, or cleft hand or foot is higher than would be expected for random independent mutations. We have previously demonstrated that maternal ingestion of a chemotherapeutic agent, busulfan, at embryonic day 11 (E11) induces these defects in various combinations in rat embryo limbs. In an effort to determine the mechanism by which busulfan disrupts digital development, we examined cell death by Nile Blue staining and TdT‐mediated dUTP nick end labeling (TUNEL) assays; we also carried out whole mount in situ hybridization for fibroblast growth factor‐8 (Fgf8), bone morphogenetic protein‐4 (Bmp4), and sonic hedgehog (Shh) to examine developmental pathways linked to these defects. In busulfan‐treated embryos, diffuse cell death was evident in both ectoderm and mesoderm, peaking at E13. The increased cell death leads to regression of Fgf8 in the apical ectodermal ridge (AER) and Bmp4 and Shh in the underlying mesoderm. The subsequent pattern of interdigital apoptosis and cartilage condensation was variably disrupted. These results suggest that busulfan manifests its teratogenic effects by inducing cell death of both ectoderm and mesoderm, with an associated reduction in tissue and a disruption in the generation of patterning molecules during critical periods of digit specification.