Fibroblast growth factor receptor signaling in kidney and lower urinary tract development.

Fibroblast growth factor receptors (FGFRs) and FGF ligands are highly expressed in the developing kidney and lower urinary tract. Several classic studies showed many effects of exogenous FGF ligands on embryonic renal tissues in vitro and in vivo. Another older landmark publication showed that mice with a dominant negative Fgfr fragment had severe renal dysplasia. Together, these studies revealed the importance of FGFR signaling in kidney and lower urinary tract development. With the advent of modern gene targeting techniques, including conditional knockout approaches, several publications have revealed critical roles for FGFR signaling in many lineages of the kidney and lower urinary tract at different stages of development. FGFR signaling has been shown to be critical for early metanephric mesenchymal patterning, Wolffian duct patterning including induction of the ureteric bud, ureteric bud branching morphogenesis, nephron progenitor survival and nephrogenesis, and bladder mesenchyme patterning. FGFRs pattern these tissues by interacting with many other growth factor signaling pathways. Moreover, the many genetic Fgfr and Fgf animal models have structural defects mimicking numerous congenital anomalies of the kidney and urinary tract seen in humans. Finally, many studies have shown how FGFR signaling is critical for kidney and lower urinary tract patterning in humans.

Quantitative skin color measurements in acanthosis nigricans patients: colorimetry and diffuse reflectance spectroscopy.

Tristimulus colorimetry and diffuse reflectance spectroscopy (DRS) are white-light skin reflectance techniques used to measure the intensity of skin pigmentation. The tristimulus colorimeter is an instrument that measures a perceived color and the DRS instrument measures biological chromophores of the skin, including oxy- and deoxyhemoglobin, melanin and scattering. Data gathered from these tools can be used to understand morphological changes induced in skin chromophores due to conditions of the skin or their treatments. The purpose of this study was to evaluate the use of these two instruments in color measurements of acanthosis nigricans (AN) lesions. Eight patients with hyperinsulinemia and clinically diagnosable AN were seen monthly. Skin pigmentation was measured at three sites: the inner forearm, the medial aspect of the posterior neck, and anterior neck unaffected by AN. Of the three, measured tristimulus L*a*b* color parameters, the luminosity parameter L* was found to most reliably distinguish lesion from normally pigmented skin. The DRS instrument was able to characterize a lesion on the basis of the calculated melanin concentration, though melanin is a weak indicator of skin change and not a reliable measure to be used independently. Calculated oxyhemoglobin and deoxyhemoglobin concentrations were not found to be reliable indicators of AN. Tristimulus colorimetry may provide reliable methods for respectively quantifying and characterizing the objective color change in AN, while DRS may be useful in characterizing changes in skin melanin content associated with this skin condition.

Acanthosis nigricans identifies youth at high risk for metabolic abnormalities.

OBJECTIVE: To determine the prevalence of abnormal glucose homeostasis and cardiovascular risk factors in youth with acanthosis nigricans (AN). STUDY DESIGN: Youth (8-14 years) were recruited from community pediatric offices. Each subject underwent a questionnaire, a targeted physical examination, and an oral glucose tolerance test. RESULTS: Subjects (n = 236) with AN of the neck (AN+) (60% Hispanic, 30% African American, 54% female, body mass index [BMI] z-score 2.3 kg/m(2)) and 51 youth without AN (65% Hispanic, 22% African American, 37% female, BMI z-score 2.1 kg/m(2)) completed the study. Twenty-nine percent of the AN+ group had abnormal glucose homeostasis, 27% had systolic blood pressure > 95th percentile, and 50% had high-density lipoprotein-cholesterol < or =5th percentile. Once corrected for sex, puberty, maternal education, and BMI z-score, AN remained significantly associated with insulin resistance and abnormal glucose homeostasis. For youth in the AN+ group, homeostasis model assessment of insulin resistance, female sex, and positive glutamic acid decarboxylase antibodies remained significantly and independently associated with impaired glucose tolerance. CONCLUSIONS: Youth in the AN+ group had severe insulin resistance, and more than 1 in 4 already had abnormal glucose homeostasis. AN identified a high-risk population, for whom appropriate interventions have the potential to attenuate or even prevent the development of diabetes and further metabolic abnormalities.

Molecular mechanism of kallikrein-related peptidase 8/neuropsin-induced hyperkeratosis in inflamed skin.

BACKGROUND: Hyperkeratosis and acanthosis occur in inflamed skin. Proliferation and differentiation of keratinocytes are important processes during epidermal repair after inflammation. Neuropsin and its human homologue kallikrein-related peptidase 8 (KLK8) have been reported to be involved in epidermal proliferation and differentiation, but the involved molecular mechanisms are obscure. OBJECTIVES: To explore the molecular mechanism of KLK8/neuropsin-induced hyperkeratosis and acanthosis in inflamed skin. METHODS: The molecular mechanism involved in KLK8/neuropsin-induced hyperkeratosis and acanthosis in inflamed skin was investigated both in vivo and in vitro using neuropsin knockout mice and KLK8 knockdown human keratinocytes. Neuropsin-related genes were identified by differential gene display. The localization and functional relationship of the molecules affected downstream of KLK8/neuropsin in normal and inflamed skin were analysed by in situ hybridization and immunohistochemistry. RESULTS: Hyperkeratosis and acanthosis in sodium lauryl sulphate-stimulated skin were markedly inhibited in neuropsin knockout mice. Knockdown of KLK8/neuropsin increased transcription factor activator protein-2α (AP-2α) expression and decreased keratin 10 expression in human keratinocytes and mouse skin, respectively. AP-2α has been reported to inhibit epidermal proliferation and keratin 10 expression. Distributional analysis showed that KLK8/neuropsin was expressed in the stratum spinosum, AP-2α was expressed in the stratum basale and the lower part of the stratum spinosum, and keratin 10 was expressed throughout the stratum spinosum. CONCLUSIONS: The above findings suggest the following mechanism of events underlying KLK8/neuropsin-induced hyperkeratosis: (i) skin inflammation increases KLK8/neuropsin expression in the stratum spinosum; (ii) the released KLK8/neuropsin inhibits AP-2α expression in the cells of the stratum basale and stratum spinosum; (iii) the decrease in AP-2α results in cell proliferation in the stratum basale and cell differentiation in the stratum spinosum, with an increase in keratin 10 expression.

Relationship of acanthosis nigricans with metabolic syndrome in obese children.

OBJECTIVES: Acanthosis nigricans is a skin symptom in obesity that helps to identify patients at high risk for dyslipidemia, hypertension, insulin resistance, and diabetes. It is the most important complication of obesity in metabolic syndrome. Studies investigating the relationship between acanthosis nigricans and metabolic syndrome in obese children are insufficient. In our study, the relationship of acanthosis nigricans and metabolic syndrome was evaluated in children. METHODS: Obese children aged between 6 and 18 years old, who were examined in the pediatric endocrinology outpatient clinic, were included. The patients' anthropometric measurements and laboratory results were recorded. Modified IDF (International Diabetes Federation) criteria for children were used in metabolic syndrome classification. RESULTS: A hundred and forty-eight obese children were evaluated. The mean age of the cases was 11.91 ± 2.94 years old. Of the cases, 56.1% were female (n=83) 43.9% (n=65) were male. In 39.9% (n=59) of cases, acanthosis nigricans was determined. Acanthosis nigricans was mostly located in the axillary area (27.1%) and the neck (16.9%). In 55.9% of the cases, it was located in more than one area. The relation of regionally detected acanthosis nigricans and metabolic syndrome was not significant (p=0.291). Metabolic syndrome was detected in 14% of 136 patients according to IDF criteria. Acanthosis nigricans and metabolic syndrome combination was present in 27.7%; however, 6.7% of the metabolic syndrome patients did not have acanthosis nigricans. There was a strong relation between metabolic syndrome and the presence of acanthosis nigricans (p=0.003). CONCLUSIONS: In our study, a correlation between acanthosis nigricans and metabolic syndrome was detected. Acanthosis nigricans is a skin sign that can be easily detected by clinician. It is an important and easy-to-detect dermatosis that helps determine patients at risk of metabolic syndrome in obese children.

Alterations of carbohydrate and lipoprotein metabolism in childhood obesity--impact of insulin resistance and acanthosis nigricans.

AIM: To study the prevalence of alterations of glucose and lipoprotein metabolism and the impact of acanthosis nigricans (AN) in childhood obesity. PATIENTS AND METHODS: 113 obese children, 57 with simple obesity (SO) and 58 with obesity and AN (OAN). Oral glucose tolerance test was performed, serum glucose, insulin and lipoprotein parameters were determined, and insulin resistance/sensitivity indices were calculated. RESULTS: Insulin resistance, basal and reactive hyperinsulinemia, impaired glucose tolerance (IGT) and dyslipidemia were found to be frequent conditions in children with OS as well as OAN. Reactive insulinemia was more pronounced in OAN than in SO, and insulin resistance was more frequent when AN was more prominent. Triglycerides were higher and HDL-C was lower, and atherogenic dyslipidemia was more frequent in OAN compared to SO. CONCLUSION: Children with obesity form a risk population. AN is a factor which can be used in metabolic risk factor clustering estimation in childhood obesity.

Changes in inflammatory markers correlated with increased testosterone after laparoscopic sleeve gastrectomy in obese Chinese men with acanthosis nigricans.

Bariatric surgery is an effective method for severe obesity and its related comorbidities. This study was performed to explore the alterations of sex hormones and inflammatory markers following laparoscopic sleeve gastrectomy (LSG) among obese Chinese men with acanthosis nigricans (AN). Sixty-five obese men who underwent LSG were enrolled, comprising simple obesity without AN (OB group, n = 20) and obesity with AN (AN group, n = 45). There were 31 healthy male controls with normal body mass index (BMI) included. Anthropometry data, inflammatory markers, sex hormones and metabolic parameters were compared preoperatively and 12 months post-operatively. At baseline, patients in the AN group were associated with more severe metabolic abnormalities than the OB and control groups. Twelve months after surgery, AN patients obtained significant improvement in skin condition and reduction in AN score. BMI, fasting insulin (FINS), and Homeostatic Model Assessment of Insulin Resistance (HOMA-IR), tumor necrosis factor-α (TNF-α) and total testosterone (TT) were significantly changed in both groups, while interleukin (IL)-6, IL-8 and C-reactive protein were changed significantly only in the AN group. Moreover, FINS, HOMA-IR, TT and IL-6 levels were changed more in the AN group than those in the OB group. Multivariate regression analysis revealed that TT increase correlated significantly with reduction in FINS and HOMA-IR in both groups, but correlated with changes in IL-6 only in the AN group. In conclusion, LSG is effective in improving the skin condition of obese men with AN. The increased TT in AN patients correlated with amelioration of inflammatory state in addition to insulin resistance after LSG.

Transmembrane helix heterodimerization in lipid bilayers: probing the energetics behind autosomal dominant growth disorders.

Here, we show that the energetics of transmembrane helix heterodimer formation can be characterized in liposomes using Förster resonance energy transfer (FRET). We present the theory and the protocol for measuring the free energy of heterodimerization, and the total (hetero and homo-dimeric) dimer fraction. We use the presented methodology to determine the propensity for heterodimer formation between wild-type fibroblast growth factor receptor 3 (FGFR3) transmembrane domain and the Ala391Glu mutant, linked to Crouzon syndrome with acanthosis nigricans.

Diabetes mellitus in Asian Indian children and adolescents.

AIM: To study the clinical and metabolic profile of type 1 and type 2 diabetes mellitus in children and adolescents in a South Asian population. RESEARCH DESIGN AND METHODS: Sixty children were recruited. They were divided into three groups: Group I--type 2 diabetes mellitus (DM2), Group II--type 1 diabetes mellitus (DM1), and Group III--healthy controls. The clinical history and biochemical parameters (HbA1c, serum insulin, C-peptide, triglycerides, total cholesterol and HDL-cholesterol) were recorded. Homeostasis model assessment for insulin resistance (HOMAIR) and quantitative insulin sensitivity check index (QUICKI) were calculated. RESULTS AND CONCLUSIONS: Children and adolescents with DM2 had a significant family history of DM and clinical features of insulin resistance, including increased body mass index, waist:hip ratio and acanthosis nigricans. They also had decreased insulin sensitivity together with dyslipidemia of metabolic syndrome, i.e. high triglyceride, high total cholesterol and low HDL-cholesterol. The presence of these predictors of cardiovascular disorders is known to contribute to morbidity and mortality. Hence, DM2 needs to be recognized early in Asian Indian children.

Adipose tissue, hepatic, and skeletal muscle insulin sensitivity in extremely obese subjects with acanthosis nigricans.

We evaluated insulin action in skeletal muscle (glucose disposal), liver (glucose production), and adipose tissue (lipolysis) in 5 extremely obese women with acanthosis nigricans (AN), who had normal oral glucose tolerance, and 5 healthy lean subjects, by using a 5-stage pancreatic clamp and stable isotopically labeled tracer infusion. Basal plasma insulin concentration was much greater in obese subjects with AN than lean subjects (54.8 +/- 4.5 vs 8.0 +/- 1.3 microU/mL, P < .001), but basal glucose and free fatty acid concentrations were similar in both groups. During stage 1 of the clamp, glucose rate of appearance (R(a)) (2.6 +/- 0.3 vs 3.7 +/- 0.3 micromol x kg FFM(-1) x min(-1), P = .02) and palmitate R(a) (2.4 +/- 0.6 vs 7.0 +/- 1.5 micromol x kg FFM(-1) x min(-1), P < .05) were greater in obese subjects with AN than lean subjects despite slightly greater plasma insulin concentration in subjects with AN (3.0 +/- 0.7 vs 1.1 +/- 0.4 microU/mL, P < .05). The area under the curve for palmitate R(a) (1867 +/- 501 vs 663 +/- 75 micromol x kg FFM(-1) x 600 min(-1), P = .03) and glucose R(a) (1920 +/- 374 vs 1032 +/- 88 micromol x kg FFM(-1) x 600 min(-1), P = .02) during the entire clamp procedure was greater in subjects with AN than lean subjects. During intermediate insulin conditions (plasma insulin, approximately 35 microU/mL), palmitate R(a) was 5-fold greater in subjects with AN than in lean subjects (2.6 +/- 1.1 vs 0.5 +/- 0.2 micromol x kg FFM(-1) x min(-1), P = .05). Maximal glucose disposal was markedly lower in obese subjects with AN than in lean subjects (13.0 +/- 0.8 vs 23.4 +/- 1.8 mg x kg FFM(-1) x min(-1), P = .01) despite greater peak plasma insulin concentration (1842 +/- 254 vs 598 +/- 38 microU/mL, P < .05). These data demonstrate obese young adults with AN have marked insulin resistance in multiple tissues. However, marked insulin hypersecretion can compensate for impaired insulin action, resulting in normal glucose and fatty acid metabolism during basal conditions.

Luteolin-7-glucoside inhibits IL-22/STAT3 pathway, reducing proliferation, acanthosis, and inflammation in keratinocytes and in mouse psoriatic model.

The epidermis is a dynamic tissue in which keratinocytes proliferate in the basal layer and undergo a tightly controlled differentiation while moving into the suprabasal layers. The balance between keratinocyte proliferation, differentiation, and death is essential, and its perturbation can result in pathological changes. Some common skin diseases, such as psoriasis, are characterized by hyperproliferation accompanied by inflammatory reactions, suggesting that molecules with topical anti-inflammatory and ROS scavenging abilities may be useful for their treatment. Here we investigate the potential of the flavone Luteolin-7-glucoside (LUT-7G) as a treatment for psoriasis. We show that LUT-7G leads to a modification of the cell cycle and the induction of keratinocyte differentiation, with modification of energy, fatty acid, and redox metabolism. LUT-7G treatment also neutralizes the proliferative stimulus induced by the proinflammatory cytokines IL-22 and IL-6 in HEKn. Moreover, in the Imiquimod (IMQ) mouse model of psoriasis, topical administration of LUT-7G leads to a marked reduction of acanthosis and re-expression of epidermal differentiation markers. Dissection of the IL-22 signalling pathway, activated by IMQ treatment, demonstrates that LUT-7G impairs the nuclear translocation of phosphorylated (activated) STAT3, blocking the IL-22 signalling cascade. Thus LUT-7G appears to be a promising compound for the treatment of hyperproliferative and inflammatory skin diseases, such as psoriasis.

An in vivo mouse model of human skin substitute containing spontaneously sorted melanocytes demonstrates physiological changes after UVB irradiation.

Human skin substitutes (HSS) have been developed for repairing burns and other acute or chronic wounds. But although the clinical utility of HSS is well known, scant attention has been paid to their cosmetic properties, especially with regard to color compatibility with the patient's complexion. In this study, we generated an HSS from mixed cell slurries containing keratinocytes and fibroblasts with and without melanocytes on the back of severe combined immunodeficient mice by means of a spontaneous cell-sorting technique. At 16 wk after grafting, Caucasian donor-derived HSS with melanocytes were macroscopically clearly darker than those without melanocytes, and a more darkly pigmented HSS was produced when cells from donors of African descent were seeded. Immunohistochemistry of c-kit, S-100, and HMB45, as well as Fontana-Masson staining and transmission electron microscopy (TEM) demonstrated that melanocytes spontaneously localized to the basal layer. Melanosome transfer to keratinocytes was correctly reorganized, and melanin was evenly dispersed in the basal and suprabasal layers. Colorimetric analysis showed a significantly lower L-value by day 14 following irradiation with 120 mJ per cm2 ultraviolet-B (UVB) (p<0.01), whereas epidermal thickness increased by 50% 1 d after exposure (p<0.01), indicating a normal physiological response to UVB irradiation. These findings suggest that HSS with spontaneously sorted melanocytes offer a means of treating both the structural and cosmetic aspects of skin conditions and trauma, such as pigmentary disorders and skin wounds, by allowing manipulation of the color and population of donor melanocytes.

Characterization of binding and phosphorylation defects of erythrocyte insulin receptors in the type A syndrome of insulin resistance.

The type A syndrome of insulin resistance and acanthosis nigricans is characterized by severe insulin resistance due to a cellular defect in insulin action. To better understand the molecular nature of this defect, we have investigated insulin binding to circulating monocytes, erythrocytes, and the Triton X-100-solubilized erythrocyte receptor, and insulin-stimulated receptor autophosphorylation using cells and receptor from three type A patients. Insulin binding in both circulating cells and the soluble extract of erythrocytes indicated a heterogeneity of defects. Patients A1 and A2 both presented a major decrease in tracer insulin binding to intact cells and soluble insulin receptor. Determination of stoichiometric binding parameters using a cooperative model indicated that in patient A1 this was due to a reduction in the number of receptors, whereas in patient A2 the affinity constant for binding was decreased. Patient A3 presented near-normal insulin binding to erythrocytes and normal binding in intact monocytes, solubilized erythrocyte receptors, and cultured fibroblasts. Affinity labeling of erythrocyte receptor from this patient revealed a normal alpha-subunit and also a normal relative distribution of the higher-molecular-weight, nonreduced oligomeric forms of the receptor. Receptor autophosphorylation was measured using the solubilized insulin receptor from erythrocytes. The maximal stimulated phosphorylation was reduced by 79%, 76%, and 52% in patients A1, A2, and A3, respectively, relative to the simultaneous control. In all three patients, the autophosphorylation was stimulated only 1.0-3.5 times the basal level compared with controls, in which the stimulation was 5.7-fold +/- 1.2 (mean +/- 1 SD, P less than 0.005). In addition, in patients A1 and A2 a decrease in basal phosphorylation was observed and in patient A2 there was a rightward shift of the dose-response curve for insulin stimulation. These data and the correlation of coupling of receptor phosphorylation with the fractional occupancy of the receptor measured in the same extract suggest that these patients exhibit three types of defects. In patient A1, there is a loss in receptor number manifested by a parallel decrease in insulin binding and receptor phosphorylation. In patient A2, there is an additional decrease in the affinity constant leading to a decrease in both binding and receptor phosphorylation with an almost linear coupling between receptor occupancy and receptor phosphorylation.(ABSTRACT TRUNCATED AT 400 WORDS)

Familial insulin resistance and acanthosis nigricans. Presence of a postbinding defect.

Type A insulin resistance, associated with acanthosis nigricans and menstrual irregularity, has been ascribed to a decreased concentration of insulin receptors. We now report four affected females from one family, a mother and three daughters (including identical twins) who appear to have the type A syndrome. Two of the kindred had no apparent ovarian dysfunction, while the other two had hyperprolactinemia without other findings of polycystic ovary disease, suggesting a genetic disease with variable penetrance. All had normal erythrocyte and monocyte insulin binding. Insulin dose-response studies to assess glucose metabolism and insulin sensitivity were performed in the affected twins. The dose response to insulin was shifted to the right with a decrease in maximal response. These results are consistent with a postbinding defect in insulin action in these patients.

Autophosphorylation of cultured skin fibroblast insulin receptors from patients with severe insulin resistance and acanthosis nigricans.

The severe insulin resistance with acanthosis nigricans seen in young women without insulin-receptor autoantibodies is characterized by hyperinsulinemia and decreased in vivo responsiveness to insulin. We evaluated the potential cellular defects in insulin-receptor binding and autophosphorylation in 12 subjects with this syndrome. When evaluated as a group, insulin binding to freshly isolated monocytes was 55% that of controls. Specific binding of insulin to skin fibroblasts in monolayer culture was 49% that of controls. Maximal insulin-stimulated receptor autophosphorylation was only 27% that of controls. Individual data demonstrated that the diminished autophosphorylation activity was out of proportion to the diminished fibroblast insulin binding in cell lines from most subjects and was less than 50% of the predicted activity in 6 of the 12 studied cell lines. These data are consistent with genetically determined defects leading to diminished numbers of cell surface insulin receptors with intact tyrosine kinase autophosphorylation in many of our cell lines. However, in at least half, there appeared to be an additional defect beyond insulin binding, resulting in a disproportionate decrease in insulin-sensitive phosphorylation of the insulin-receptor beta-subunit.

Functional characteristics of decreased insulin receptors on fibroblasts obtained from a subject with severe insulin resistance and acanthosis nigricans.

In a patient with severe insulin resistance and acanthosis nigricans, a decrease in the number of insulin receptors has been found on freshly isolated monocytes and cultured fibroblasts compatible with a primary or genetic decrease in cell-surface insulin receptors. To determine the functional characteristics of the remaining receptors on these cells, insulin-stimulated glucose uptake, insulin internalization, and insulin-induced receptor loss were evaluated in monolayer fibroblasts obtained from this subject. Maximal insulin stimulation of 2-deoxyglucose was markedly blunted, compatible with abnormal insulin responsiveness due to a functional impairment of the remaining receptors. In the presence of chloroquine, the acanthotic subject's fibroblasts internalized more insulin per available receptor compared with the normal cell line, suggesting an accelerated rate of insulin internalization. When the rate of insulin internalization was more directly determined by assessing the rate of appearance of acid-resistant, cell-associated radioactivity at 37 degrees C, a similar increase in insulin internalization rate was evident. When downregulation was assessed, insulin's ability to induce receptor loss in the acanthotic subject's cell line was augmented. Thus, a primary or genetic decrease in insulin receptors on cultured fibroblasts from a patient with acanthosis nigricans and insulin resistance is associated with functional impairment of the remaining receptors leading to significant alterations in ligand processing and subsequent insulin action.

Carbohydrate (CHO) oxidation in patients with type B insulin resistance.

Total body carbohydrate (CHO) and fat oxidation rates, plasma glucose, free fatty acid, and insulin concentrations were determined in two patients with the type B syndrome of severe insulin resistance and in normal controls in response to insulin infusions (1-100 mU/kg/min) and to a test meal. In addition, insulin was infused at higher rates (10-1000 mU/kg/min) in one of the two patients while plasma glucose concentrations were clamped first at 195 and later at 244 mg/dl. During the postabsorptive state, resting metabolic rates (RMR) were 914 and 979 cal/min/1.73 m2 in the two patients (controls: 1018 +/- 85 cal/min/1.73 m2). Patients met 85% and 83% of their caloric requirements by oxidizing fat (controls: 63 +/- 7%). Protein oxidation accounted for 15% and 13% (controls: 14 +/- 3%) of energy requirements and CHO oxidation for 0% and 0%, respectively, in both patients (controls: 23 +/- 5%). Infusion of insulin at a rate of 10 mU/kg/min raised plasma insulin concentrations from 1400 and 440 microU/ml to 6000 and 2500 microU/ml, respectively, in patients 1 and 2 (controls: from 4 +/- 0.3 to 1288 +/- 50 microU/ml), but had no effects on rates of CHO, fat, or protein oxidation in either patient. By comparison, the rate of CHO oxidation in controls rose about sixfold from 40 +/- 8 to 234 +/- 12 mg/min/1.73 m2. Infusion of 1000 mU/kg/min in combination with an increase in plasma glucose from 195 +/- 1.1 to 244 +/- 1.9 mg/dl in patient 1, however, raised CHO oxidation from 0 to 36 mg/min/1.73 m2 and lowered fat oxidation from 105 to 69 mg/min/1.73 m2.(ABSTRACT TRUNCATED AT 250 WORDS)

Glycosaminoglycan deposition in the acanthosis nigricans lesions of the polycystic ovary syndrome.

Skin biopsy specimens of acanthosis nigricans (AN) lesions were obtained from seven women with the polycystic ovary (PCO) syndrome and insulin resistance (IR). All the patients had normal thyroid function test results and fasting hyperinsulinemia with an exaggerated insulin response to oral glucose. Acanthosis nigricans lesions exhibited prominent deposits of glycosaminoglycan (GAG) consisting mostly of hyaluronic acid in the papillary dermis. Normal amounts of GAGs were found in control biopsy specimens obtained from areas of the skin not involved by AN and from skin of the nape of the neck or axillae in three normal women. These studies demonstrate that GAG deposition is a regular component of AN skin in patients with PCO and IR. The cause of these infiltrates remains to be determined.

Insulin receptor status in disease states of man.

When insulin or any peptide hormone binds to its receptor on the surface of a target cell, it initiates a series of biochemical steps that ultimately lead to the characteristic action of the hormone. The strength of the signal generated by the hormone depends equally on the hormone concentration, the receptor concentration, and the receptor affinity. Not only do hormone concentrations change rapidly and widely in vivo but so do receptor concentration and affinity. In hormone resistant states, any step in the biochemical pathway of hormone action at the target cell may be involved. Studies of insulin receptors in people indicate that the insulin receptor is altered in many common disorders such as obesity and diabetes, as well as in rare disorders such as extreme insulin resistance due to circulating antibodies directed at the insulin receptor itself. By responding to both intracellular and extracellular events, the insulin receptor is, therefore, a major site for the regulation of target cell responsiveness in vivo.