Extracellular volume measured by whole body CT scans predicts chronic cardiotoxicity in breast cancer patients treated with neoadjuvant therapies based on anthracyclines: A retrospective study.

INTRODUCTION: Neoadjuvant chemotherapies for breast cancer (BC) are effective but potentially cardiotoxic, and expose long survivors at risk of chemotherapy-related cardiac dysfunction (CTRCD). Unfortunately, early screening for CTRCD has actual diagnostic limits. Myocardial extracellular volume (mECV) is a radiological marker used in cardiac CT scans and cardiac magnetic resonance for diagnosis and follow-up of CTRCD. It can be measured in whole-body CT (WB-CT) scan, routinely performed in patients at high risk of relapse, to evaluate CTRCD occurrence during oncological follow-up. METHODS: 82 WB-CT scans were examined at baseline (T0) and during oncological follow-up at first year (T1) and fifth year (T5) after the end of neoadjuvant treatment. mECV was measured at 1 min (PP) and 5 min (DP) after contrast injection. 31 echocardiograms were retrieved in T1 to perform a linear correlation between mECV and left ventricular ejection fraction (LVEF). RESULTS: mECV values in T0 were similar between the two groups both in PP and in DP. Significant results were found for PP values in T1 (37.0 % vs 32 %, p = 0.0005) and in T5 (27.2 % vs 31.2 %, p = 0.025). A cut-off value of 35 % in PP proved significant in T1 (OR = 12.4, p = 0.004), while mECV was inversely correlated with LVEF both in PP (adj-S = -3.54, adj-p = 0.002) and in DP (adj-S = -2.51, adj-p = 0.0002), suggesting a synergistic action with the age at diagnosis (p < 0.0001, respectively). CONCLUSIONS: WB-CT scans performed during oncological reassessment in patients at high-risk of recurrence could be used for CTRCD screening in cardiovascular low-risk patients, especially in aging patients with mECV values above 35 %.

International consensus (ICON) on management of otitis media with effusion in children.

Otitis media with effusion (OME) is a common childhood disease defined as the presence of liquid in the middle ear without signs or symptoms of acute ear infection. Children can be impacted mainly with hearing impairment and/or co-occurring recurrent acute otitis media (AOM) thus requiring treatment. Although many meta-analyses and national guidelines have been issued, management remains difficult to standardize, and use of surgical and medical treatments continue to vary. We convened an international consensus conference as part of the 2017 International Federation of Oto-rhino-laryngological Societies Congress, to identify best practices in OME management. Overall, regional differences were minor and consensual management was obtained on several important issues. At initial assessment, although a thorough medical examination is necessary to seek reflux, allergy or nasal obstruction symptoms; an age-appropriate auditory test is the only assessment required in children without abnormal history. Non-surgical treatments poorly address the underlying problem of an age-dependent dysfunctional Eustachian tube; auto-inflation seems to be the only beneficial, low-risk and low-cost non-surgical therapy. There was a clear international recommendation against using steroids, antibiotics, decongestants or antihistamines to treat OME, because of side-effects, cost issues and no convincing evidence of long-term effectiveness. Decisions to insert tympanostomy ventilation tubes should be based on an auditory test but also take into account the child's context and overall hearing difficulties. Tubes significantly improve hearing and reduce the number of recurrent AOM with effusion while in place. Adjuvant adenoidectomy should be considered in children over four years of age, and in those with significant nasal obstruction or infection.

Prenatal course of metaphyseal anadysplasia associated with homozygous mutation in MMP9 identified by exome sequencing.

Metaphyseal anadysplasia (MANDP) is a rare autosomal recessive form of skeletal dysplasia characterized by normal length at birth and transitory bowing of the legs. Although several families with MANDP have been reported, homozygous mutations in the matrix metalloproteinase type 9 (MMP9) gene have been described in only one consanguineous family, and thus the pre and postnatal phenotypic spectrum is still obscure. A clinically similar but more severe type is caused by autosomal-dominant inheritance and is caused by mutations in matrix metalloproteinase type 13 gene (MMP13). Here, we report the prenatal and early postnatal course of two affected sib fetuses with early sonographic evidence of long bone shortening and postnatally no metaphyseal changes. Whole-exome sequencing revealed homozygous mutation in MMP9 in both fetuses suggesting a diagnosis of MANDP. We propose that MANDP should be considered in pregnancies with early prenatal shortening of the long bones without associated finding of lethal skeletal dysplasias. In addition, the finding of homozygous mutation in non-consanguineous parents of Jewish-Caucasus ancestry may suggest unawareness of such relation or the occurrence of a founder mutation in this gene.

GH safety workshop position paper: a critical appraisal of recombinant human GH therapy in children and adults.

Recombinant human GH (rhGH) has been in use for 30 years, and over that time its safety and efficacy in children and adults has been subject to considerable scrutiny. In 2001, a statement from the GH Research Society (GRS) concluded that 'for approved indications, GH is safe'; however, the statement highlighted a number of areas for on-going surveillance of long-term safety, including cancer risk, impact on glucose homeostasis, and use of high dose pharmacological rhGH treatment. Over the intervening years, there have been a number of publications addressing the safety of rhGH with regard to mortality, cancer and cardiovascular risk, and the need for long-term surveillance of the increasing number of adults who were treated with rhGH in childhood. Against this backdrop of interest in safety, the European Society of Paediatric Endocrinology (ESPE), the GRS, and the Pediatric Endocrine Society (PES) convened a meeting to reappraise the safety of rhGH. The ouput of the meeting is a concise position statement.

Personalized approach to growth hormone treatment: clinical use of growth prediction models.

The goal of growth hormone (GH) treatment in a short child is to attain a fast catch-up growth toward the target height (TH) standard deviation score (SDS), followed by a maintenance phase, a proper pubertal height gain, and an adult height close to TH. The short-term response variable of GH treatment, first-year height velocity (HV) (cm/year or change in height SDS), can either be compared with GH response charts for diagnosis, age and gender, or with predicted HV based on prediction models. Three types of prediction models have been described: the Kabi International Growth Hormone Study models, the Gothenburg models and the Cologne model. With these models, 50-80% of the variance could be explained. When used prospectively, individualized dosing reduces the variation in growth response in comparison with a fixed dose per body weight. Insulin-like growth factor-I-based dose titration also led to a decrease in the variation. It is uncertain whether adding biochemical, genetic or proteomic markers may improve the accuracy of the prediction. Prediction models may lead to a more evidence-based approach to determine the GH dose regimen and may reduce the drug costs for GH treatment. There is a need for user-friendly software programs to make prediction models easily available in the clinic.

Cirugía urológica en pacientes de 80 años y más: ¿es la edad un factor de riesgo para el desarrollo de complicaciones postoperatorias? / Urological surgery in patients 80 years and older: is age a risk factor for the development of postoperative complications?

La expectativa de vida ha ido aumentando en Chile y en el mundo, lo que ha causado un gran impacto a nivel del número de cirugías que se realiza en la población añosa. El objetivo de este trabajo es describir la experiencia de nuestro centro en cirugías urológicas en pacientes mayores de 80 años y analizar que factores aumentan el riesgo de complicaciones postquirúrgicas.Materiales y método: Análisis retrospectivo de 138 cirugías urológicas realizadas en 120 pacientes mayores de 80 años, durante los años 2000 a 2012. Se obtuvo información sociodemográfica, riesgo quirúrgico (ASA), tipo y duración de cirugía realizada, complicaciones post-operatorias (escala de Clavien) y tiempo de hospitalización. Los datos obtenidos fueron analizados mediante el programa SPSS v17. Se realizó análisis multivariado y se estableció el riesgo relativo para el desarrollo de complicaciones. Se consideró signi ficativo p<0,05. Resultado: La edad promedio de los pacientes fue de 84+/-3.7 años, 86.2 por ciento fueron hombres. El 96.7 por ciento presentaba algún tipo de comorbilidad, con predominio de hipertensión arterial (60,84 por ciento) y diabetes mellitus tipo 2 (24,16 por ciento). La mayoría de las intervenciones fue de complejidad intermedia (77.27 por ciento), donde la anestesia regional (56,8 por ciento) y la vía endo urológica (84,78 por ciento) fueron las más utilizadas, con un tiempo operatorio promedio de 62+/-52.4 minutos. El riesgo quirúrgico prevalente fue ASA2 (62.7 por ciento). El promedio de hospitalización fue de 2,8+/-2.7 días. El 15.21 por ciento de los pacientes presentó algún tipo de complicación, con predominio de clasifi cación tipo 1 de Clavien (38 por ciento). En el análisis multivariado se evidenció como factores de riesgo signi ficativos para complicaciones, edad mayor a 90 años (p=0.03), presencia de insu ciencia renal (p=0.01), portar 4 o más comorbilidades (p=0.04), cirugía mayor a 3 horas (p=0.03) y tener riesgo quirúrgico ASA3 (p=0.04)...

Life expectancy has been increasing in Chile and in the World. This has caused a great impact over the number of surgeries being performed in the elderly population. The aim of this paper is to describe the experience of our center in urological surgery in patients older than 80 years and analyze which factors increase the risk of postoperative complications.Materials and methods: Retrospective analysis of 138 urological surgeries performed in 120 patients older than 80 years, during the years 2000-2012. Sociodemographic information, surgical risk (ASA), type and duration of surgery, postoperative complications (Clavien scale) and length of hospitalization was obtained. The data were analyzed using SPSS v17. Multivariate analysis was performed and the relative risk for developing complications was established. Signi cance was p <0.05. Average age of the patients was 84 +/- 3.7 years, 86.2percentwere men. The 96.7 percenct had some kind of comorbidity, with prevalence of hypertension (60.84 percent) and diabetes mellitus type 2 (24.16 percent). Most of the interventions was of intermediate complexity (77.27percent), where regional anesthesia (56.8 percent) and endourological aproach (84.78 percent) were the most used, with average operative time of 62 +/- 52.4 minutes. Most common Surgical risk was ASA2 (62.7 percent). Average hospital stay was 2.8 +/- 2.7 days. 15.21 percent of patients had some type of complication, with a predominance of type 1 Clavien classication (38 percent). The multivariate analysis showed signi cant risk factors for complications: age greater than 90 years (p = 0.03), renal failure (p = 0.01), carrying 4 or more comorbidities (p = 0.04), surgery Langer than 3 hours (p = 0.03) and ASA3 surgical risk (p =.04). No mortality was reported in our series. In this study, although most of our patients underwent endourological procedures, we evidence that surgery in patients older than 80 years is feasible...

Insulin-like growth factor-I in growth and metabolism.

Deficiency of insulin-like growth factor-I (IGF-I) results in growth failure. A variety of molecular defects have been found to underlie severe primary IGF-I deficiency (IGFD), in which serum IGF-I concentrations are substantially decreased and fail to respond to GH therapy. Identification of more patients with primary or secondary IGFD is likely with investigative and diagnostic progress, particularly in the assessment of children with idiopathic short stature. Diagnosis of IGFD requires accurate and reliable IGF-I assays, adequate normative data for reference, and knowledge of IGF-I physiology for proper interpretation of data. Recombinant human IGF-I (rhIGF-I) treatment improves stature in patients with severe primary IGFD, and has also been shown to improve glycaemic control and insulin sensitivity in patients with severe insulin resistance. Ongoing studies of patients receiving rhIGF-I will allow further evaluation of the clinical utility of this treatment, with concurrent increase in our understanding of IGF-I and conditions of IGFD.

[Insulin growth factor-I-based dosing of growth hormone therapy in children: a randomized, controlled study].

Weight-based dosing of growth hormone (GH) is the standard of therapy in short children although insulin-like growth factor-I (IGF-I) is a major mediator of GH actions on growth. Objective: to test whether the IGF-I levels achieved during GH therapy are determinants of the growth responses to GH therapy. This was a two-year open-label, randomized IGF-I concentration-controlled trial. Prepubertal short children [n = 172; mean age 7.53 years; mean height SD score (HT-SDS - 2.64] with low IGF-I levels (mean IGF-I SDS - 3.56) were randomized to receive one of two GH dose-titration arms in which GH dosage was titrated to achieve an IGF-I SDS at the mean [IGF(low) group, n = 70) or the upper limit of the normal range [+2 SDS, IGF(high) group, n = 68] or to a comparison group of conventional GH dose of 40 mg/kg/day (n = 34). The multicenter study was performed in the outpatient centers. The primary outcome measure was to determine changes in HT-SDS during 2-year therapy. One hundred and forty-seven patients completed the trial. Target IGF-I levels were achieved in the dose-titration arms within 6-9 months. The changes in HT-SDS were +1.0, +1.1, and +1.6 for conventional, IGF(low), and IGF(high), respectively, with IGF(high) showing significantly greater linear growth response (p < 0.001), compared with the two other groups). The IGF-I(high) arm required higher doses ( > 2.5 times) than the IGF-I(low) arm, and these GH doses were highly variable (20-346 mg/kg/day). Multivariate analyses suggest that the rise in IGF-I SDS significantly impacted height outcome along with the GH dose and the pretreatment peak-stimulated GH level. IGF-I-based GH dosing is clinically feasible and allows maintaining serum IGF-I concentrations within the desired target range. Titrating the GH dose to achieve higher IGF-I target results in improved growth responses, although at higher average GH doses.

Future e(+)e(-) colliders' sensitivity to Hbb coupling and CP violation.

We perform a complete simulation of the process e(+)e(-)-->bbvv, where nu can be an electron, muon, or tau neutrino, in the context of a general Higgs coupling to b quarks. We parametrize the Hbb; coupling as (m(b)/v)(a+igamma(5)b). Taking into account interference effects between pure Higgs and Standard Model contributions, we find that sensitivities of the order of 2% and 20% can be obtained at a future e(+)e(-) collider for deviations of the a and b parameters, respectively, from their Standard Model values. Combining our analysis with an independent measurement of Gamma(H-->bb) can provide evidence about the CP nature of the Higgs sector.

Insulin-like growth factor binding protein-3 generation as a measure of GH sensitivity.

A total of 198 subjects were randomized to either high-dose (0.05 mg/kg.d) or low-dose (0.025 mg/kg.d) GH for 7 d; the alternate dose was then received after a 2-wk washout period. Groups included in the study were: normal, GH-insensitive (GHI; homozygous for the E180 splice mutation); heterozygous GHI (carriers of the E180 splice mutation); GH-deficient; and idiopathic short stature. Serum IGF binding protein-3 (IGFBP-3) concentrations (collected on d 1, 5, and 8 of treatment weeks) were GH-dependent, with significant elevation by d 5 of treatment, regardless of dose, in all normal subjects. GHI subjects had low baseline IGFBP-3 and poor or no response to either low- or high-dose GH. Heterozygous subjects, however, did not differ from age-matched normals with regard to IGFBP-3 generation. All GH-deficient subjects had subnormal baseline concentrations of IGFBP-3; most, but not all, were able to generate levels into normal ranges by 8 d of therapy. Children with idiopathic short stature showed a better response in IGFBP-3 generation compared with that previously observed with IGF-I, reaching concentrations in normal range with either dose of GH, suggesting that any GHI in this group is relatively limited to IGF-I production. For the diagnosis of GHI, the highest sensitivity (100%) and specificity (92%) was found on d 8 of the high-dose GH-IGFBP-3 generation test. Failure to raise both IGF-I and IGFBP-3 lowered sensitivity to 82-86% with low-dose GH, and 86-91% with high-dose GH.

The metabolic effects of short-term administration of physiological versus high doses of GH therapy in GH deficient adults.

OBJECTIVE: GH treatment has demonstrated favourable effects on most features of GH deficiency in hypopituitary adults. However, most studies employed supraphysiological GH doses, resulting in deterioration in insulin sensitivity (SI). The short-term metabolic effects of physiological doses of GH therapy in GH deficient (GHD) adults are largely unknown. We therefore compared the effects of short-term administration of two 'physiological' ('lowest' dose: 0.0017 mg/kg/day; 'low' dose: 0.0033 mg/kg/day) with two 'supraphy-siological' ('high' dose: 0.010 mg/kg/day; 'highest' dose: 0.025 mg/kg/day) GH doses on SI, beta-cell function, IGF-1 and IGFBPs -1 and -3 in a group of GHD adults. PATIENTS AND METHODS: Thirteen GHD adults were recruited (seven men, aged 23-63 years). For each of the four doses, six patients (three men) were allocated randomly to undergo a 7-day treatment phase. Fasting blood samples were collected daily (days 1-8), and SI and beta-cell function were calculated using the homeostasis model assessment (HOMA). RESULTS: All four GH doses increased IGF-1, IGFBP-3 and IGF-1/IGFBP-3 ratio, and decreased IGFBP-1 from day 3 onwards (P < 0.05). The highest dose increased fasting glucose (P < 0.001), insulin (P < 0.001) and beta-cell function (P < 0.001), but decreased SI (P < 0.001). The high and low doses did not modify fasting glucose and insulin, SI or beta-cell function, whereas the lowest dose enhanced beta-cell function (P < 0.05). The overall increase in the GH dose increased IGF-1, IGFBP-3, fasting glucose and insulin (P < 0.001), demonstrated a positive correlation with the final change in fasting glucose (r = 0.5, P < 0.05) and insulin (r = 0.8, P < 0.001) and a negative correlation with final SI (r = -0.5, P < 0.05). CONCLUSIONS: Our results suggest that short-term administration of the highest GH dose induced insulin resistance, whereas the lowest dose (0.0017 mg/kg/day) could represent the optimal starting dose in GHD adults due to its beneficial effects on beta-cell function without compromising SI. It is, however, yet to be determined whether the positive effects of the lowest GH dose on beta-cell function can be demonstrated over a longer period of time.

Effect of IGFBP-3 on IGF- and IGF-analogue-induced insulin-like growth factor-I receptor (IGFIR) signalling.

Insulin-like growth factor binding protein-3 (IGFBP-3) binds IGF-I and IGF-II with high affinity, at least an order of magnitude higher than the affiniy of the IGFs for the IGFIR. It has been hypothesized that IGFBP-3 inhibits IGF binding to the IGFIR via a mechanism independent of its ability to sequester IGFs. In the present study, we examined the effects of IGFBP-3 and its proteolytic fragments on the initial events of the IGFIR signalling pathway. IGFBP-3 inhibited IGF-I-, IGF-II-, Des(1-3)IGF-I- and Long(R3)IGF-I-induced IGFIR phosphorylation in a dose-dependent manner at similar concentration range but not QAYL-induced IGFIR-P. The((1-97))IGFBP-3 fragment was able to inhibit only IGF-I-induced IGFIR-P. The((1-97))IGFBP-3 fragment but not intact IGFBP-3 inhibited insulin-induced IGFIR-P. Monolayer cross-linking with [(125)I]IGFBP-3 indicated that there is no direct interaction of IGFBP-3 with the IGFIR. This study demonstrates that the effect on the initial step of IGFIR signalling by IGFBP-3 is largely due to its ability to sequester IGF and the IGF analogues in the extracellular milieu and not the result of any interaction of IGFBP-3 with the IGFIR or a mechanism independent of its ability to bind IGFs.

Implications of the AHRQ evidence report on acute otitis media.

OBJECTIVE: To familiarize otolaryngologists with the Agency for Healthcare Research and Quality (AHRQ) Evidence Report on Acute Otitis Media (AOM) that reviews the natural history and role of antibiotics in management. The report, by the Southern California Evidence-Based Practice Center (SC-EPC), is the most recent of 15 literature syntheses published by the AHRQ. DATA SOURCES: MEDLINE (1966 to present), Cochrane Library, EMBASE, BIOSIS, HealthSTAR, and other computerized databases; manual reference search of proceedings, articles, reports, and guidelines. STUDY SELECTION: Randomized trials and cohort studies relevant to the natural history of AOM and the efficacy of antimicrobial therapy. AOM was defined by the 11-member technical expert panel (including 2 authors, RMR and MLC) as middle-ear effusion with the rapid onset of signs or symptoms of middle ear inflammation. DATA EXTRACTION: Two physician reviewers at the Southern California Evidence-Based Practice Center independently rated the articles and extracted data. DATA SYNTHESIS: Children receiving placebo or no antimicrobial had a pooled clinical success rate of 81% at 1 to 7 days (95% CI, 72% to 90%), with no increase in suppurative complications when followed closely. Amoxicillin or ampicillin increased the absolute success rate by 12.3% (95% CI, 2.8% to 21.8%) in 5 studies pooled using random effects meta-analysis. The antimicrobial benefit was robust to sensitivity analysis. In contrast, success rates were not influenced by the choice or duration of therapy. CONCLUSIONS: The AHRQ report emphasizes middle-ear effusion as a preeminent criteria for AOM diagnosis and provides extensive evidence tables on natural history and antimicrobial impact. About 8 children must receive antibiotics to avoid 1 clinical failure, but children younger than age 2 years or with severe symptoms may benefit more. The report is a starting point for organizations seeking to develop AOM guidelines, performance measures, and other quality improvement tools.

The IGF-I generation test revisited: a marker of GH sensitivity.

IGF-I generation tests were developed over 20 yr ago and are currently used in differentiating GH insensitivity (GHI) from other disorders characterized by low serum IGF-I. Nevertheless, generation tests have never been adequately characterized, and insufficient normative data are available. One hundred and ninety-eight subjects [including normal subjects; subjects with GHI, GH deficiency (GHD), and idiopathic short stature (ISS); and heterozygotes for the E180 splice GH receptor mutation] were randomized to self-administration of either a high (0.05 mg/kg x d) or a low (0.025 mg/kg x d) dose of GH for 7 d. After a 2-wk washout period, they received the alternate dose. Samples were collected on d 1, 5, and 8 of each treatment period. In normal individuals, IGF-I generation was GH dependent at all ages, and little advantage was observed in using the higher dose of GH or extending beyond the d 5 sample. Some GHD patients had IGF-I levels, both baseline and stimulated, that overlapped levels in the verified GHI patients. Subjects heterozygous for the E180 GH receptor splice mutation did not show a decreased responsiveness to GH. ISS patients had low-normal IGF-I levels that did not stimulate beyond the baseline normative ranges for age. These data provide the first large scale effort to provide preliminary normative IGF generation data and evaluate the GH sensitivity of patients with GHI, GHD, and ISS.

A bicyclic and hsst2 selective somatostatin analogue: design, synthesis, conformational analysis and binding.

A backbone bridged and disulfide bridged bicyclic somatostatin analogue, compound 1 (PTR-3205), was designed and synthesized by solid-phase methodology. The binding of compound 1 to the five different somatostatin receptors, expressed in CHO or COS-7 cells, indicate a high degree of selectivity towards hsstr2. The three-dimensional structure of this compound has been determined in DMSO-d(6) and in water by 1H NMR and by molecular dynamics simulations. Similar backbone conformations were observed in both solvents. We have established direct evidence that the backbone of this bicyclic somatostatin analogue assumes a 'folded' conformation in solution, where the lactam ring extends roughly in the plane of the beta-turn. The pharmacophoric region Phe-(D)-Trp-Lys-Thr of compound 1 is in accord with that of both the Veber compound L-363,301 (Merck) and sandostatin. We believe that the enhanced selectivity towards the hsst2 receptor, in comparison with other analogues, is due to its large hydrophobic region, composed of the lactam ring and the Phe side chains at positions 1 and 8.

Growth hormone insensitivity syndromes: lessons learned and opportunities missed.

The concept of growth hormone (GH) insensitivity has evolved since the condition was originally identified in 1966, and we now know that the primary defect involved is in the GH receptor. Cloning of the receptor molecule has led to great progress in our understanding of GH insensitivity (GHI) and its therapy, including the roles of GH and insulin-like growth factor I (IGF-I) in growth and development, and the relationships between height and serum levels of GH, IGF-I and their binding proteins. Despite the success of work on GHI and IGF-I, a number of opportunities have been missed in the past. The differences between the metabolic effects of GH and IGF-I are not fully understood, while measurements of IGF-I and IGF-binding protein 3 are perhaps not the ideal means of diagnosing GHI. Finally, the use of IGF-I to treat GHI has a number of limitations, and work is underway to develop alternative therapies.

Sensitivity to growth hormone-the perspective. Round table discussion.

This round table discussion addressed the utility of insulin-like growth factor I (IGF-I) as a predictor of growth hormone (GH) action, the relationship between IGF-I response to GH and growth response, the possibility of a spectrum of both GH sensitivity and IGF-I sensitivity, and an examination of the possible need to acknowledge indicators of GH action in children which are distinct from those in adults.

Mutation of three critical amino acids of the N-terminal domain of IGF-binding protein-3 essential for high affinity IGF binding.

The N-terminal domain is conserved in all members of the IGF-binding protein superfamily. Most recently, studies have demonstrated the importance of an IGF-binding protein N-terminal hydrophobic pocket for IGF binding. To examine more critically the amino acids important for IGF binding within the full-length IGF-binding protein-3 protein while minimizing changes in the tertiary structure, we targeted residues I56, L80, and L81 within the proposed hydrophobic pocket for mutation. With a single change at these sites to the nonconserved glycine there was a notable decrease in binding. A greater reduction was seen when both L80 and L81 were substituted with glycine, and complete loss of affinity for IGF-I and IGF-II occurred when all three targeted amino acids were changed to glycine. Furthermore, the ability of the IGF-binding protein-3 mutants to inhibit IGF-I-stimulated phosphorylation of its receptor was a reflection of their affinity for IGF, with the lowest affinity mutants having the least inhibitory effect. These studies, thus, support the hypothesis that an N-terminal hydrophobic pocket is the primary site of high affinity binding of IGF to IGF-binding protein-3. The mutants provide a tool for future studies directed at IGF-dependent and IGF-independent actions of IGF-binding protein-3.

Interaction of IGF-binding protein-related protein 1 with a novel protein, neuroendocrine differentiation factor, results in neuroendocrine differentiation of prostate cancer cells.

Neuroendocrine cells have been implicated in many cancers, including small cell lung, cervical, breast, and prostate carcinomas. The increase in neuroendocrine cell number in prostate cancer has been reported to correlate with poor prognosis, progressive tumors, and androgen insensitivity. The mechanisms involved in this differentiation remain unknown. IGF-binding protein-related protein 1 is a member of the IGF-binding protein superfamily and has recently been shown to exhibit differentiation and tumor suppression activity in prostate cancer cell lines stably overexpressing IGF-binding protein-related protein 1. From a yeast two-hybrid screen, a novel IGF-binding protein-related protein 1-interacting protein was identified. Immunocytochemical techniques indicate that this protein, 25.1, and intracellular IGF-binding protein-related protein 1 colocalize in the nucleus. When 25.1 is transiently expressed in a stable prostate cancer cell line overexpressing IGF-binding protein-related protein 1, cells assume a neuritic-like morphology with long dendritic-like processes and express the neuroendocrine markers chromogranin A and neuron-specific enolase. We propose that 25.1 (neuroendocrine differentiation factor) together with IGF-binding protein-related protein 1 can induce neuroendocrine cell differentiation in prostate cancer cells.