Mosaicism of activating FGFR3 mutations in human skin causes epidermal nevi

Epidermal nevi are common congenital skin lesions with an incidence of 1 in 1,000 people; however, their genetic basis remains elusive. Germline mutations of the FGF receptor 3 (FGFR3) cause autosomal dominant skeletal disorders such as achondroplasia and thanatophoric dysplasia, which can be associated with acanthosis nigricans of the skin. Acanthosis nigricans and common epidermal nevi of the nonorganoid, nonepidermolytic type share some clinical and histological features. We used a SNaPshot multiplex assay to screen 39 epidermal nevi of this type of 33 patients for 11 activating FGFR3 point mutations. In addition, exon 19 of FGFR3 was directly sequenced. We identified activating FGFR3 mutations, almost exclusively at codon 248 (R248C), in 11 of 33 (33%) patients with nonorganoid, nonepidermolytic epidermal nevi. In 4 of these cases, samples from adjacent histologically normal skin could be analyzed, and FGFR3 mutations were found to be absent. Our results suggest that a large proportion of epidermal nevi are caused by a mosaicism of activating FGFR3 mutations in the human epidermis, secondary to a postzygotic mutation in early embryonic development. The R248C mutation appears to be a hot spot for FGFR3 mutations in epidermal nevi.     

Tyrosine kinase inhibitor NVP-BGJ398 functionally improves FGFR3-related dwarfism in mouse model

Achondroplasia (ACH) is the most frequent form of dwarfism and is caused by gain-of-function mutations in the fibroblast growth factor receptor 3–encoding (FGFR3-encoding) gene. Although potential therapeutic strategies for ACH, which aim to reduce excessive FGFR3 activation, have emerged over many years, the use of tyrosine kinase inhibitor (TKI) to counteract FGFR3 hyperactivity has yet to be evaluated. Here, we have reported that the pan-FGFR TKI, NVP-BGJ398, reduces FGFR3 phosphorylation and corrects the abnormal femoral growth plate and calvaria in organ cultures from embryos of the Fgfr3^Y367C/+ mouse model of ACH. Moreover, we demonstrated that a low dose of NVP-BGJ398, injected subcutaneously, was able to penetrate into the growth plate of Fgfr3^Y367C/+ mice and modify its organization. Improvements to the axial and appendicular skeletons were noticeable after 10 days of treatment and were more extensive after 15 days of treatment that started from postnatal day 1. Low-dose NVP-BGJ398 treatment reduced intervertebral disc defects of lumbar vertebrae, loss of synchondroses, and foramen-magnum shape anomalies. NVP-BGJ398 inhibited FGFR3 downstream signaling pathways, including MAPK, SOX9, STAT1, and PLCγ, in the growth plates of Fgfr3^Y367C/+ mice and in cultured chondrocyte models of ACH. Together, our data demonstrate that NVP-BGJ398 corrects pathological hallmarks of ACH and support TKIs as a potential therapeutic approach for ACH.     

Potential use of craniosynostotic osteoprogenitors and bioactive scaffolds for bone engineering

The cranial bone has a very limited regenerative capability. Patients with craniosynostosis (the premature fusion of cranial sutures, leading to skull abnormalities) often require extensive craniofacial reconstruction and repeated surgery. The possibility of grafting autologous osteoprogenitor cells seeded on bioabsorbable matrices is of great potential for inducing regeneration of craniofacial structure and protecting the brain from external insult. To this purpose we have studied the behaviour of normal and craniosynostotic mouse osteoblast cell lines, and of human primary osteoprogenitors from craniosynostotic patients. We have monitored their ability to grow and differentiate on plastic and on a scaffold composed of bioactive glass and bioabsorbable polymer by live fluorescent labelling and expression of bone differentiation markers. Cells from syndromic patients display a behaviour very similar to that observed in the stable mouse cell line we generated by introducing the human FGFR2-C278F, a mutation found in certain craniosynostosis, into MC3T3 osteblastic cells, indicating that the mutated cell line is a valuable model for studying the cellular response of human craniosynostotic osteoblasts. Both normal and mutated calvarial osteoprogenitors can attach to the bioactive scaffold, although mutated cells display adhesion defects when cultured on plastic. Furthermore, analysis of bone differentiation markers in human osteoblasts shows that the composite mesh, unlike PLGA(80) plates, supports bone differentiation. The ability of the mesh to support homing and differentiation in both normal and mutant osteoprogenitors is important, in view of further developing autologous biohybrids to repair cranial bone deficits also in craniosynostotic patients undergoing extensive reconstructive surgery.     

Integrated strategy for fast and automated molecular characterization of genes involved in craniosynostosis

BACKGROUND: Craniosynostosis, the premature fusion of 1 or more sutures of the skull, is a common congenital defect, with a prevalence of 1 in 2500 live births. Untreated progressive craniosynostosis leads to inhibition of brain growth and increased intracranial and intraorbital pressure. The heterogeneity of clinical phenotypes and the overlap of the various associated syndromes render the correct diagnosis of the different craniosynostoses particularly difficult. METHODS: To identify 10 common mutations in the genes for fibroblast growth factor receptors 2 and 3 (FGFR2 and FGFR3), we developed a microelectronic microchip assay that exploited the PCR multiplexing format and coupled it with serial addressing and probe hybridization on the same pad. For the molecular characterization of patients who tested negative in the microchip screening, we also developed conditions for denaturing HPLC (DHPLC) analysis of the most mutated regions of FGFR2 and FGFR3 and the entire coding region of the TWIST1 gene. RESULTS: In our cohort of 159 patients with various craniosynostosis syndromes, mutations were found in 100% of patients with Apert syndrome, 83.3% with Pfeiffer syndrome, 72.7% with Crouzon syndrome, 50.0% with Saethre-Chotzen syndrome, 27.7% with plagiocephaly, 31.8% with brachicephaly, 20% of complex cases, and 6.9% of mixed cases. No mutations were found in syndromic cases. CONCLUSIONS: The combined microchip-DHPLC strategy allows rapid and specific molecular diagnosis of craniosynostosis and is an effective tool for the medical and surgical management of these common congenital anomalies in a newborn or an infant with a developmental defect of the cranial vault.     

Selective insulin action on skin, ovary, and heart in insulin-resistant states

States of hyperinsulinemia with resistance to insulin action on glucose disposal are frequently associated with proliferative tissue abnormalities of the skin (acanthosis nigricans), ovary, and heart. That insulin may be involved in the pathogenesis of these growth-related abnormalities despite resistance to its metabolic effects mediated through the insulin receptor is suggested by the known ability of high concentrations of insulin to stimulate DNA synthesis and cell proliferation in vitro through the insulin-like growth factor I (IGF-I) receptor. IGF-I receptors are present in skin keratinocytes, some ovarian tissue compartments, and in the heart. Furthermore, ovarian tissue from hyperinsulinemic insulin-resistant women responds to supraphysiologic insulin concentrations in vitro by enhanced steroidogenesis. Cultured, transformed T-lymphocytes from an infant with leprechaunism fail to augment basal-colony formation in response to physiologic insulin concentrations in vitro (compared to a doubling seen in normal subjects), but respond normally to supraphysiologic insulin concentrations, the effect of which is competitively inhibited by a monoclonal antibody to the IGF-I receptor. Thus, insulin action mediated through the IGF-I receptor may initiate growth-promoting tissue effects in the face of limited insulin effect on glucose metabolism. Such spillover actions may add to the morbidity associated with states of clinical insulin resistance.     

Acanthosis Nigricans: An Opportunity for Intervention

The appearance of the velvety and hyperpigmented plaques of acanthosis nigricans (AN) on the skin of overweight and obese children is an early sign of insulin resistance. The presence of AN provides the opportunity for nurse practitioners to identify youth at risk for type 2 diabetes, and offers the chance to encourage youth and families to make lifestyle changes, and to adopt healthier eating habits.     

Disruption of Fgf10/Fgfr2b-coordinated epithelial-mesenchymal interactions causes cleft palate

Classical research has suggested that early palate formation develops via epithelial-mesenchymal interactions, and in this study we reveal which signals control this process. Using Fgf10-/-, FGF receptor 2b-/- (Fgfr2b-/-), and Sonic hedgehog (Shh) mutant mice, which all exhibit cleft palate, we show that Shh is a downstream target of Fgf10/Fgfr2b signaling. Our results demonstrate that mesenchymal Fgf10 regulates the epithelial expression of Shh, which in turn signals back to the mesenchyme. This was confirmed by demonstrating that cell proliferation is decreased not only in the palatal epithelium but also in the mesenchyme of Fgfr2b-/- mice. These results reveal a new role for Fgf signaling in mammalian palate development. We show that coordinated epithelial-mesenchymal interactions are essential during the initial stages of palate development and require an Fgf-Shh signaling network.     

Second-trimester molecular prenatal diagnosis of sporadic Apert syndrome following suspicious ultrasound findings.

Apert syndrome, an autosomal dominant disorder characterized by craniosynostosis, mid-facial malformations, symmetric bony syndactyly of hands and feet, and varying degrees of mental retardation, is most frequently caused by a de novo mutation. Two missense mutations in the fibroblast growth factor receptor 2 (FGFR2) gene have been found to account for the disorder in approximately 98% of affected patients. Seven cases of prenatal ultrasound diagnosis have been reported. Although one earlier diagnosis has been made in a familial case, sporadic cases have not been definitively diagnosed until the third trimester when craniosynostosis is usually detected. We report a second-trimester molecular diagnosis of a sporadic case, based on the ultrasound observation of fetal 'mitten hands' and craniosynostosis. We discuss the approach to such ultrasound features, given the current availability of molecular diagnosis for Apert syndrome.     

Critical comparison of diffuse reflectance spectroscopy and colorimetry as dermatological diagnostic tools for acanthosis nigricans: a chemometric approach

Quantification of skin changes due to acanthosis nigricans (AN), a disorder common among insulin-resistant diabetic and obese individuals, was investigated using two optical techniques: diffuse reflectance spectroscopy (DRS) and colorimetry. Measurements were obtained from AN lesions on the neck and two control sites of eight AN patients. A principal component/discriminant function analysis successfully differentiated between AN lesion and normal skin with 87.7% sensitivity and 94.8% specificity in DRS measurements and 97.2% sensitivity and 96.4% specificity in colorimetry measurements.     

Is Acanthosis Nigricans a reliable indicator for risk of type 2 diabetes?

Acanthosis nigricans (AN) is a thickening and hyperpigmentation of the skin commonly found on the neck, axilla, or groin and is generally caused by hyperinsulinemia, a consequence of insulin resistance associated with obesity. Insulin resistance is a primary risk factor for the development of type 2 diabetes, hypercholesterolemia, and hypertension. Screening for acanthosis nigricans is controversial and not recommended by the Centers for Disease Control and Prevention; however, some states, such as Texas, are implementing AN screenings in schools to identify those children who are at highest risk for developing type 2 diabetes. With the current epidemics of obesity and diabetes, school nurses will see students in the health office with AN and should be knowledgeable about this skin condition and the association with hyperinsulinemia and obesity. The school nurse's role is to educate and assist students and their families in seeking appropriate medical advice based on current knowledge of risk factors. This article will explore the controversy associated with screening for AN and make recommendations for school nursing practice.     

代谢综合征在相关皮肤病中的研究进展

代谢综合征（MS）是一组以血脂异常、高血压、腹型肥胖、胰岛素抵抗为主要表现的临床综合征,是糖尿病和心血管疾病的危险因素。近年来MS与皮肤病方面的研究日益增多,该文就MS在相关皮肤病包括银屑病、痤疮、化脓性汗腺炎、黑棘皮病、扁平苔藓及雄激素性脱发等发病机制的研究进展作一综述,为MS及相关皮肤病的防治提供新的思路。     

Therapeutic approach in insulin resistance with acanthosis nigricans

The aim of the present study was to evaluate the effect of metformin in very obese subjects with acanthosis nigricans. Five patients (two obese children, mean age 14.4 +/- 0.6 yr, mean BMI 35.2 +/- 1.9 kg/m2 and normal glucose tolerance, and three newly diagnosed obese type 2 diabetic patients, mean age 37.7 +/- 3.2 yr, mean BMI 37.7 +/- 2.9 kg/m2) were enrolled in the study Insulin secretion was measured during oral glucose tolerance (OGT) and intravenous glucose tolerance (IVGT) tests. Insulin resistance was assessed by the homoeostasis model assessment (HOMA) index. All the patients were treated with metformin at a mean daily dose of 2.23 +/- 0.45 g. Six months after initiation of therapy we found a significant reduction in AUC for insulin secretion during OGTT (p < 0.05), due to reduction in both basal and stimulated insulin secretion (p<0.05). Body weight was reduced by mean 4.7 +/- 1.9% and body fat mass by 8.95 +/- 3.7%. We have demonstrated a significant decrease of 36.3% in insulin resistance (p < 0.01). Our results demonstrate that metformin reduces hyperinsulinaemia, body weight and fat mass and improves insulin sensitivity in patients with insulin resistance and acanthosis nigricans.     

The prevalence of the HNF-1alpha G319S mutation in Canadian aboriginal youth with type 2 diabetes

OBJECTIVE: To investigate the prevalence of the unique HNF-1alpha G319S mutation in a population of aboriginal youth with type 2 diabetes and to describe the relationship between clinical and historical characteristics and the presence or absence of the HNF-1alpha G319S mutation. RESEARCH DESIGN AND METHODS: Participating youth were genotyped for the G319S mutation of the HNF-1alpha gene. Clinical, laboratory, and historical data were collected via chart review (blinded to genotype results). Comparison data were derived from another study involving young nondiabetic pregnant aboriginal women. RESULTS: A total of 51 youth seen sequentially in a type 2 diabetes clinic participated in this study. Of these, 21 (41.2%) had at least one copy of the mutant allele. The allele frequency in the study population was 0.29 (95% CI 0.20-0.38), which was significantly different from the allele frequency of 0.13 in the comparison population (chi(2) = 6.78, P = 0.009). The frequency of the homozygous mutation (S319/S319) was 0.18. Mean BMI was significantly lower (P = 0.002), mean HbA(1c) was significantly higher (P = 0.02), and acanthosis nigricans was significantly less frequent (P = 0.004) in those with the mutation compared with the wild type. Mean insulin levels were lower and insulin sensitivity (assessed by homeostasis model assessment [HOMA]) was greater in the homozygote group compared with the wild-type group (P = 0.002 and P = 0.0007, respectively). A dose-dependent gradient was observed for these characteristics. CONCLUSIONS: These data support the association between the HNF-1alpha G319S mutation and early-onset type 2 diabetes in this population. Those with the mutation lacked clinical characteristics of insulin resistance (e.g., obesity and acanthosis nigricans) and had lower insulin levels, suggesting that an insulin-secretory and/or -production defect plays an important role in the development of diabetes in this group. Further investigation of the pathophysiology of the S319 homo- and heterozygote is needed because it may impact treatment and/or prevention of this disease.     

Increased calvaria cell differentiation and bone matrix formation induced by fibroblast growth factor receptor 2 mutations in Apert syndrome.

Apert syndrome, associated with fibroblast growth factor receptor (FGFR) 2 mutations, is characterized by premature fusion of cranial sutures. We analyzed proliferation and differentiation of calvaria cells derived from Apert infants and fetuses with FGFR-2 mutations. Histological analysis revealed premature ossification, increased extent of subperiosteal bone formation, and alkaline phosphatase- positive preosteoblastic cells in Apert fetal calvaria compared with age-matched controls. Preosteoblastic calvaria cells isolated from Apert infants and fetuses showed normal cell growth in basal conditions or in response to exogenous FGF-2. In contrast, the number of alkaline phosphatase- positive calvaria cells was fourfold higher than normal in mutant fetal calvaria cells with the most frequent Apert FGFR-2 mutation (Ser252Trp), suggesting increased maturation rate of cells in the osteoblastic lineage. Biochemical and Northern blot analyses also showed that the expression of alkaline phosphatase and type 1 collagen were 2-10-fold greater than normal in mutant fetal calvaria cells. The in vitro production of mineralized matrix formed by immortalized mutant fetal calvaria cells cultured in aggregates was also increased markedly compared with control immortalized fetal calvaria cells. The results show that Apert FGFR-2 mutations lead to an increase in the number of precursor cells that enter the osteogenic pathway, leading ultimately to increased subperiosteal bone matrix formation and premature calvaria ossification during fetal development, which establishes a connection between the altered genotype and cellular phenotype in Apert syndromic craniosynostosis.     

Evidence for heterogeneous pathogenesis of insulin-treated diabetes in black and white children

OBJECTIVE: We have previously reported differences in the prevalence of beta-cell autoantibodies (AAs) in black and white children with insulin-treated diabetes, suggesting that the disease pathogenesis may be more heterogeneous among racial groups than previously thought. To further explore this issue, we compared clinical, biochemical, and autoimmune characteristics at disease diagnosis and follow-up treatment in an expanded number of black and white children with and without the presence of AAs. RESEARCH DESIGN AND METHODS: The study cohort of 130 black children and adolescents, aged <19 years, diagnosed with diabetes and treated with insulin at time of diagnosis (January 1979 to December 1998) were matched with an equal number of white children by age at onset, sex, and year of diagnosis. RESULTS: The black children had a higher prevalence of obesity (43 vs. 11%) and acanthosis nigricans (21 vs. 1%) than white children and a lower prevalence of AAs. Compared with black children who had AAs, those with no AAs were older and had a higher prevalence of obesity, acanthosis nigricans, and parental diabetes. However, one of four of the black children with AAs was obese and/or had acanthosis nigricans. Among white children, the absence of AAs was not associated with any differences in terms of obesity or acanthosis nigricans compared with those with AAs. Similar to their black counterparts, white children without antibodies were older and had a higher prevalence of parental diabetes. Although treatment with an insulin sensitizer was used, insulin therapy was rarely discontinued on follow-up. CONCLUSIONS: These pediatric subjects, irrespective of autoimmunity, often showed characteristics associated with type 2 diabetes. These characteristics were more frequently displayed in black than in white children. Our data suggest that childhood diabetes may constitute a spectrum of pathogenic mechanisms that may overlap, including those typically associated with both type 1 and type 2 diabetes. This finding could have therapeutic implications.     

Certain Aspects of Hypothyroidism in Childhood

The skin may show nonspecific or nonmalignant signs of internal malignancy and thus be a clue to its early diagnosis. Infections which do not respond properly to treatment, pruritus, erythemas, hemorrhagic phenomena, abnormal pigmentations and trophic changes may be manifestations of internal malignant disease. Conditions related specifically to carcinoma include Bowen's disease, Paget's disease and acanthosis nigricans. Internal lymphomatous disease may be indicated by prurigo, pyoderma, viral infections and exfoliative dermatitis.     

Successful immunosuppressive therapy in a patient with autoantibodies to insulin receptors and immune complex glomerulonephritis

Altered mental status, acanthosis nigricans, immune complex glomerulonephritis with nephrotic syndrome, fasting hypoglycemia, and postprandial hyperglycemia associated with anti-insulin receptor antibodies (type B insulin resistance) developed in a 43-year-old black woman who initially was treated for diabetes mellitus. Her HLA phenotype was A2, A29, Bw45(w6), B13(w4), Cw3, DR1 (DQw1). Her serum contained immune complexes, low complement levels, and antibodies that bound to the glomerular mesangium of mouse kidney. All clinical and serologic abnormalities resolved with combination cyclophosphamide and glucocorticoid treatment, and low doses of these agents have maintained the remission for more than a year.     

Ursache und Diagnostik der lagebedingten Plagiozephalie

In recent years an increasing incidence of positional plagiocephaly has been observed. The reason for this form of asymmetry of the skull is unclear. From the viewpoint of manual medicine in the majority of cases there is a functional disturbance especially in the region of the C0–C1 and the C1–C2 joint which leads to a preferential positioning of the head. The supine sleeping position for infants, which has been recommended for years, leads to flattening of the back of the head due to gravitation, mostly on the side of the preferred head rotation. Symmetrical central flattening (brachycephaly) has also been reported but is less common. Positional plagiocephaly must be differentiated from craniosynostosis and other diseases linked to asymmetry of the skull. To determine the severity of positional plagiocephaly there are as yet no uniformly used measuring points or standardized measuring methods. The “cranial asymmetry screening” measurement method is recommended in this article as an orientation measurement procedure within the framework of initial diagnostics in practice for evaluation of the extent of skull asymmetry. Non-invasive, economic 3-dimensional procedures are used for studies.     

肝星状细胞增殖与p38丝裂原活化蛋白激酶信号传导通路的关系

背景：肝星状细胞的激活、增殖导致肝纤维化,p38丝裂原活化蛋白激酶信号通路可参与调控细胞增殖。目的：探讨SB203580作用于乙醛刺激的大鼠肝星状细胞后p38丝裂原活化蛋白激酶活性变化和细胞增殖变化。方法：体外培养大鼠肝星状细胞株,在乙醛干预的基础上加入不同浓度的p38特异性抑制剂SB203580进行培养,并设置对照。以Westernblot检测磷酸化p38蛋白表达水平变化,MTT比色法检测细胞增殖。结果与结论：乙醛刺激后大鼠肝星状细胞内磷酸化p38水平增强,细胞增殖明显。使用5,10,20μmol/L SB203580能明显抑制乙醛刺激的肝星状细胞增殖（P〈0.05）,加大浓度至30μmol/L时,抑制作用更明显（P〈0.01）,抑制率为43.9%,而磷酸化p38水平也降低（P〈0.05）。结果证实,抑制p38丝裂原活化蛋白激酶活性可能影响肝星状细胞的增殖。