Association between CYP4A11 and EPHX2 genetic polymorphisms and chronic kidney disease progression in hypertensive patients.

BACKGROUND: There are evidence indicating that some metabolites of arachidonic acid produced by cytochromes P450 (CYP) and epoxide hydroxylase (EPHX2), such as hydroxyeicosatetraenoic acids (HETEs), epoxyeicosatrienoic acids (EETs) or dihydroxyeicosatrienoic acids (DHETEs), play an important role in blood pressure regulation and they could contribute to the development of hypertension (HT) and kidney damage. Therefore, the main aim of the study was to evaluate whether the genetic polymorphisms of CYP2C8, CYP2C9, CYP2J2, CYP4F2, CYP4F11 and EPHX2, responsible for the formation of HETEs, EETs and DHETEs, are related to the progression of impaired renal function in a group of patients with hypertension. METHODS: 151HT patients from a hospital nephrology service were included in the study. Additionally, a group of 87 normotensive subjects were involved in the study as control group. For HT patients, a general biochemistry analysis, estimated glomerular filtration rate and genotyping for different CYPs and EPHX2 variant alleles was performed. RESULTS: CYP4A11 rs3890011, rs9332982 and EPHX2 rs41507953 polymorphisms, according to the dominant model, presented a high risk of impaired kidney function, with odds ratios (OR) of 2.07 (1.00-4.32; P=0.049) 3.02 (1.11-8.23; P=0.030) and 3.59 (1.37-9.41; P=0.009), respectively, and the EPHX2 rs1042032 polymorphism a greater risk according to the recessive model (OR=6.23; 95% CI=1.50-25.95; P=0.007). However, no significant differences in allele frequencies between HT patients and in normotensive subjects for any of the SNP analysed. In addition, the patients with diagnosis of dyslipidemia (n=90) presented higher frequencies of EPHX2 K55R (rs41507953) and *35A>G (rs1042032) variants than patients without dyslipidemia, 4% vs. 14% (P=0.005) and 16 vs. 27% (P=0.02), respectively. CONCLUSIONS: In this study has been found higher odds of impaired renal function progression associated with rs3890011 and rs9332982 (CYP4A11) and rs41507953 and rs1042032 (EPHX2) polymorphisms, which may serve as biomarkers for improve clinical interventions aimed at avoiding or delaying, in chronic kidney disease patients, progress to end-stage kidney disease needing dialysis or kidney transplant.

Comparative Analysis of Type I Keratin Expression By Nail Consistency: An Immunohistochemistry Study.

The nail plate is one of the essential structures of the nail apparatus and is highly keratinized, making it difficult to handle this tissue experimentally. Different types of nail consistency were identified by applying distal pressure to the nail plate. To analyze the relationship between the keratins expressed in the nail plate and nail consistency, we chose a sample of 32 adult individuals (age 49.81±3.21 y) with the same number of each sex, who had a similar percentage of nail consistency types (56.25% hard consistency nails and 43.75% soft consistency nails). Immunohistochemical analyses showed that hard consistency nails contain more keratin 17 than soft consistency nails (P=0.026). These novel results allow nail consistency to be defined by the differential expression of keratins in the nail plate, and have potential clinical implications for the diagnosis of possible nail disorders and/or systemic disease.

Assessment of Visual Diagnosis by Podiatrists for HPV and Onychomycosis: The Need for Complementary Tests.

Onychomycosis and human papillomavirus (HPV) plantar warts are common in clinical practice. Clinical diagnosis is based on searching for pathognomonic signs and symptoms. However, due to misdiagnosis, podiatrists may unnecessarily prescribe antifungal treatments or burn lesions with chemical agents. The objective of this study was to assess podiatrists' visual diagnosis of these infections and their willingness to use complementary tests. A 12-item questionnaire was developed to assess visual diagnostic ability. The diagnoses of all lesions were verified before the questionnaire was sent out. The respondents were 415 podiatrists with a range of years of experience. While 86.3% of podiatrists considered complementary tests for onychomycosis necessary, only 21.4% used them regularly. As many as 60.2% would leave a distal subungual onychomycosis untreated based on visual diagnosis. In the case of HPV, only 14.5% of respondents considered complementary tests necessary, although 76.6% would treat a non-HPV lesion with regular chemical agents. Years of experience did not affect the percentage of misdiagnoses. Complementary tests are needed in clinical practice to avoid unnecessary treatments. Podiatrists easily identify clear signs and symptoms but have difficulty making differential diagnoses. Research should focus on ensuring complementary tests are available to health professionals.

Preliminary Evidence of the Efficacy of Nitric Acid Treatment in Onychomycosis.

Onychomycosis is the main cause of toenail disorders and is produced by a fungal infection. It is becoming more prevalent because of new lifestyles and immunosuppression statuses. The therapeutic approach to onychomycosis is under considerable study because of the lengthy treatments that require strong patient commitment, the limited efficacy of treatments, the inclusion of active substances that can be hepatotoxic and cause pharmacological interactions, and/or the questionable efficacy of treatments due to a lack of clinical trials. This study responds to the demand for rapid treatment with minimal pharmacological interactions. METHODS: The efficacy of nitric acid 60% treatment in patients with onychomycosis was monitored and studied. The antifungal efficacy of nitric acid was measured by microbiological culture before and after treatment and the clinical evolution of nail dystrophy was quantitatively measured by monitoring with the Onychomycosis Severity Index (OSI). RESULTS: The results show that, with the protocol used, nitric acid 60% painlessly cured 40% (microbiologic cure) of the cases treated, and in all cases, clinical improvement was observed (p = 0.011). CONCLUSIONS: The treatment with nitric acid 60% is as efficient as conventional treatments, requires less patient compliance of the treatment and produces no pharmacological interactions, providing alternative treatment in the case of hepatotoxicity.

Diagnostic techniques in HPV infections and the need to implement them in plantar lesions: A systematic review.

INTRODUCTION: Human papillomavirus has been reported as the etiological cause of most cervical cancers and other potentially malignant lesions. It also affects other areas, producing benign tumors on the skin. Plantar warts are a common problem found in clinical practice and share signs and symptoms with other dermatological conditions. Diagnosis of HPV infection remains a hot topic in research. METHOD: The present work systematically reviews the literature on the diagnostic techniques available in the clinical setting for any type of lesion produced by the virus and compares the techniques identified to those found in use for foot lesions. RESULTS: Results showed a variety of diagnostic methods, including molecular techniques, which exhibit more sensitivity than other methods but are less frequently applied to plantar lesions, where visual inspection is the most frequent method but can lead to errors. CONCLUSION: The techniques identified need to be applied to plantar lesions to improve differential diagnosis in clinical practice. EXPERT OPINION: Research will continue to grow and a proper diagnostic technique for plantar lesions will be available in the near future.

Identification of Fungi Involved in Onychomycosis in Patients of a Spanish Rural Area.

Onychomycosis is one of the most frequent reasons for visiting podiatrist clinics. Complementary tests and the accurate identification of the infectious agents are key issues for a successful treatment of onychomycosis. This is particularly important when lifestyle, age and immunodepressed patients increase the prevalence of non-dermatophyte fungal infection. In this paper, we describe issues related to onychomycosis prevalence in a population of patients, mostly with rural lifestyles, visiting a podiatry clinic in a rural area of Spain. A total of 51 cases were studied with an average age of 65.96 ± 21.28 years (the youngest being 16 years and the oldest being 95 years). Fungal agents were isolated using conventional sampling and microbiological culture techniques. The results obtained with these techniques were compared with the results obtained with a direct methodology using molecular biology, by PCR and nucleotide sequencing of the ITS-5.8S rDNA fragment. The classical culture methodology confirmed the infection in 76.5% of the samples (n = 39), while the PCR confirmed the infection in 84.3% (n = 51) of the nails, although the difference between these results did not show statistical significance (p = 0.388). We found a high variability in agents, with more yeasts than dermatophytes as etiological agents of onychomycosis. However, only among individuals older than 65 years, was the difference between yeasts (82%) and dermatophytes (18%) was statistically significant (p = 0.004). Among the agents of non-dermatophyte onychomycosis, we found predominantly fungi (yeasts) of the Candida genus, interestingly with no isolates of Candida albicans, and moulds of the Aspergillus genus.

Solubilization in vitro of tea tree oil and first results of antifungal effect in onychomycosis.

INTRODUCTION: Onychomycosis is the main cause of nail alteration. Hepatotoxicity, interference and low adherence to pharmacological treatment are associated. Therefore, our objective was to assess the in vitro effectiveness of tea tree essential oil (less harmful) against main causative agents of these infections. MATERIAL AND METHODS: Thrichophyton rubrum and Thrichophyton mentagrophytes were isolated and inoculated at a concentration of 3 × 105 CFU/mL in potato agar dextrose and tea tree essential oil at different concentrations to assess its effect by counting colony forming units and radial growth. RESULTS: Trichophyton rubrum growth inhibition was obtained at concentrations higher than 0.04% of the essential tea tree oil (p = 0.004). In the case of Thrichophyton mentagrophytes, inhibition was obtained at 0.02% (p = 0.017), and even complete inhibition at a final concentration of the oil at 0.07%. CONCLUSIONS: Tea tree essential oil inhibits the in vitro growth of the fungus and may be a less harmful alternative to the onychomycosis treatment.

Fractional modeling of flexural behavior of toenail plates: First step for clinical purposes.

This work presents an identification procedure of flexural behavior of toenail plates in twenty subjects with no history of feet or nail injury as of in-vivo measurements. In particular, four different mechanical models are considered to describe such properties, ranging from the pure elastic to viscoelastic behavior, the latter from the classical and fractional points of view. The quality of the adjustment of each model is examined by a group of performance indices. Experimental data show that the best identification is achieved by the fractional order viscoelastic model for all subjects. These novel results in modeling flexural behavior of toenails are consistent with the published literature suggesting that viscoelastic materials may be successfully modeled with derivatives of fractional order. This could contribute, together with additional variables, to help health professionals, and more especially podiatrists, to have reliable and quantitative measures of the nail flexural behavior which can be susceptible of treatment or for prevention.

Predictive Model of Nail Consistency Using Scanning Electron Microscopy with Energy-Dispersive X-Ray.

The nail plate is made up of tightly packed keratin-rich cells. Factors such as the special distribution of the intermediate filaments in each layer (dorsal, intermediate, and ventral), the relative thickness of the layers, and their chemical composition define the characteristics of each nail. The main objective of this study is to determine nail consistency by calculating a predictive model based on elemental composition analysis using scanning electron microscopy. Nail consistency was determined in 57 participants (29 women and 28 men) in two age groups (young people and adults). Elemental composition was analysed in each layer using scanning SEM-EDS, and nail plate thickness was measured by image analysis. A total of 12 elements were detected in nail plates, of which carbon, nitrogen, phosphorus, sulphur, and calcium showed significant differences between layers (p-values ≤ 0.01). The level of calcium in the dorsal layer was the main predictive variable in calculating the predictive model of consistency, with 75.4% correctly classified cases. Elemental analysis in each layer of the nail plate by SEM-EDS can be used to develop a predictive model of nail consistency that will help health professionals to objectively determine nail consistency.

First-year health degree students in the dissection room: Analysis of adaptation to practical classes.

Human anatomy is a core subject that students of all health degrees are required to pass. Practical classes with human cadavers are a widely used educational resource in medicine, but are less frequent in other health degrees. Determining how first-year podiatry, nursing, and physiotherapy students cope with human anatomy practical classes and identifying the presence of physical reactions and possible causes of distress they experience in the dissection room are essential steps in designing a guidance plan to address students' needs. A questionnaire was distributed to 172 first-year students in non-medical health degrees immediately after their first visit to the dissection room. The questionnaire comprised 29 Yes/No questions to determine students' physical reactions, causes of distress and coping methods. The most frequent physical reactions were disgust, uneasiness and nausea. The main causes of distress were the smell of the cadavers, the smell of the dissection room and the sight of the cadavers. The coping methods used were being with friends, eating before the practical class and practicing beforehand with anatomical atlases and CDs. No significant differences were found between gender and the three variables analyzed (number of physical reactions, number of causes of distress and number of coping methods) (p-value >0.216), although differences were found between the type of health degree and the number of physical reactions and causes of distress (p-values = 0.028 and 0.001, respectively).

Prevalence of foot disorders according to chronic kidney disease stage.

BACKGROUND: Chronic kidney disease (CKD) is a public health disease that affects 15.1% of the adult population. Although a high prevalence (94.1%) of skin disorders has been detected in people on haemodialysis or with advanced CKD, few studies have analysed foot disorders at initial CKD stages. OBJECTIVES: To analyse the prevalence of foot disorders according to CKD stage. PARTICIPANTS: A total of 209 people with a mean age of 73.2 ± 13.8 years (52.0% women) in the nephrology department of Virgen del Puerto Hospital, Plasencia (Spain) were examined from January 2018 to April 2019. MEASUREMENTS: CKD stages were determined by nephrologists according to the Kidney Disease Improving Global Outcomes Guideline. An expert podiatrist identified foot disorders. Data were statistically treated with the IBM SPSS Statistics. Comparisons between variables were analysed by the χ2  test or Fisher's exact test, with a significance level of less than 5%. RESULTS: The prevalence of foot disorders was high for skin disorders (97.6% dermatopathies and 66.0% keratopathies), nail disorders (98.5% onychopathies) and toe deformities (97.1%). People at initial and intermediate stages presented more keratopathies (hyperkeratosis at G1 and G3a and pinch callus at G3a). Stage G1 showed fewer changes in nail colour and half and half nails. Stage G4 showed more claw toes and hematoma and stage G5 more Beau's lines, changes in skin colour, hematomas and thin shiny skin. CONCLUSIONS: The high prevalence of foot disorders detected in people with CKD requires specific and personalised professional care to relieve symptoms and avoid complications, helping to improve the quality of life of people with this condition.

Solubilization in vitro of tea tree oil and first results of antifungal effect in onychomycosis. / Solubilización in vitro del aceite de árbol de té y primeros resultados de su efecto antifúngico en onicomicosis.

INTRODUCTION: Onychomycosis is the main cause of nail alteration. Hepatotoxicity, interference and low adherence to pharmacological treatment are associated. Therefore, our objective was to assess the in vitro effectiveness of tea tree essential oil (less harmful) against main causative agents of these infections. MATERIAL AND METHODS: Trichophyton rubrum and Trichophyton mentagrophytes were isolated and inoculated at a concentration of 3x105 CFU / mL in potato agar dextrose and tea tree essential oil at different concentrations to assess its effect by counting colony forming units and radial growth. RESULTS: Trichophyton rubrum growth inhibition was obtained at concentrations higher than 0.04% of the essential tea tree oil (p = 0.004). In the case of Trichophyton mentagrophytes, inhibition was obtained at 0.02% (p = 0.017), and even complete inhibition at a final concentration of the oil at 0.07%. CONCLUSIONS: Tea tree essential oil inhibits the in vitro growth of the fungus and may be a less harmful alternative to the onychomycosis treatment.

Prevalence of Potential Drug-Drug Interaction Risk among Chronic Kidney Disease Patients in a Spanish Hospital.

Chronic kidney disease (CKD) is a major health problem worldwide and, in Spain, it is present in 15.1% of individuals. CKD is frequently associated with some comorbidities and patients need to be prescribed multiple medications. Polypharmacy increases the risk of adverse drug reactions (ADRs). There are no published studies evaluating the prevalence of potential drug-drug interactions (pDDIs) among CKD patients in any European country. This study was aimed to determine the prevalence, pattern, and factors associated with pDDIs among CKD patients using a drug interactions program. An observational cross-sectional study was carried out at Plasencia Hospital, located in Spain. Data were collected among patients with CKD diagnoses and pDDIs were assessed by the Lexicomp® Drug Interactions platform. Data were obtained from 112 CKD patients. A total number of 957 prescribed medications were acknowledged, and 928 pDDIs were identified in 91% of patients. Age and concomitant drugs were significantly associated with the number of pDDIs (p < 0.05). According to the results, the use of programs for the determination of pDDIs (such as Lexicomp®) is recommended in the clinical practice of CKD patients in order to avoid serious adverse effects, as is paying attention to contraindicated drug combinations.

The bacteriostatic effect of controlled-flux electrolyzed acidic solution on healthy hallucal skin.

BACKGROUND: There are various treatment protocols to manage the increased bacterial load in plantar ulcers. Recently, Controlled-Flux Electrolyzed Acidic Solution (CFEAS), with a pH less than 3, has appeared to be an effective option since its antimicrobial effect could help in the healing of those ulcers. In order to evaluate its potential in this sense, the aim of the present study was to compare bacterial growth on healthy hallucal skin using two types of bandaging (control and Controlled-Flux Electrolysed Acidic Solution). MATERIAL AND METHODS: In a sample of 19 healthy subjects, two experiments were performed. In the first, for each subject, two identical hallux bandages were applied in the early morning. At random between left and right foot, either physiological saline (wetting every 2 h) was applied or nothing (control). In the second, two days later, new bandages were applied as before, but now either wetting with Controlled-Flux Electrolysed Acidic Solution (experimental, again wetting every 2 h) or nothing (control). In each experiment, the bacterial load in the nail fold was assessed at the first moment and after 10 h from standard counts of bacterial colony forming units (CFU). RESULTS: In the first experiment, the CFU counts had increased significantly (p < 0.05) in both toes after the 10-h period. In the second experiment, while the bacterial load increased significantly (p = 0.001) from 0.68 ±â€¯0.8 × 104 CFU/cm2 (the "pre" sample) to 1.3 ±â€¯0.9 × 104 CFU/cm2 (the "post" sample) in the control toe, in the experimental CFEAS toe, the pre sample bacterial load was 0.61 ±â€¯0.6 × 104 CFU/cm2, and the post sample 0.9 ±â€¯0.8 × 104 CFU/cm2, with no significant difference between them (p = 0.221). Negative cultures were obtained in 3 cases (15.78%) of the experimental toe post sample, and equal post and pre counts in 2 cases (10.5%). CONCLUSION: Controlled-Flux Electrolyzed Acidic Solution has an effect on healthy hallucal skin that is bacteriostatic, and in some cases bactericidal. This effect could be very helpful in treating plantar ulcers when there is a greatly increased bacterial load in the wound, thus potentially favoring the normal formation of granulation tissue in the skin and normal healing and closure of the ulcer.

[Gastrointestinal bleeding and acute hepatic failure by leptospirosis: an entity that should not be forgotten]. / Hemorragia digestiva e insuficiencia hepática aguda por leptospirosis: una entidad que no debemos olvidar.

Leptospirosis disease is caused by the spirochete Leptospira. It is a worldwide distribution zoonosis, with predominance in the tropics. In Spain, it is not frequent but some cases have been noticed especially in humid areas surrounded by rivers, lakes or ponds, such as Catalonia, Andalucia or the Valencian Community. It is transmitted by a variety of animals such as cows or rats, that are infected either by direct contact with these animals or their urine, or indirectly by consuming or being in contact with water contaminated by their urine. The clinical manifestations are very variable, being asymptomatic or not very symptomatic in most of the patients. Unusually, leptospirosis presents with a first phase with fever, myalgias, liver injury or different organs hemorrhage, followed by a second phase with the presence of jaundice due to hepatic failure. Weil's disease is a kind of severe leptospirosis characterized by hepatic failure with jaundice and acute renal failure, associated with high mortality rates.The diagnosis is based on serological techniques and DNA detection by PCR. The treatment consists of life support measures and antibiotic therapy. A patient with Weil's disease and leptospirosis digestive bleeding is presented, with a fulminant clinical course. In order to achieve an early diagnosis, the need to keep this entity in mind must be emphasized, especially in favorable epidemiological environments as the one of this patient.

Relation Between Nail Consistency and Incidence of Ingrown Toenails in Young Male Runners.

BACKGROUND: This study examines the possible influence of factors such as nail shape and consistency, sex, and sports activity on the development of the most common nail disorders in a population of young people. METHODS: The nail plates of 140 young people (66 females and 74 males) were studied. Of these 140 participants, 72 were runners who trained more than 10 hours a week and competed regularly, and 68 did not habitually do any sports activity. Nail shape, consistency, and disorders were examined, taking into account the sex of the participants and their sports activity. RESULTS: A hard nail consistency is more frequent in runners (74.4%) than in people who do no sports activity (25.6%). In contrast, a soft nail consistency is more prevalent in participants who do no sports activity (70%) than in runners (30%). It was also shown that onychocryptosis is related to sex, as females had a higher prevalence of this nail disorder (57.8%, P = .016). However, young male runners showed the highest and most significant percentage of the presence of onychocryptosis (74.1%; P = .002). CONCLUSIONS: Sports activity by young male runners whose nails have a hard consistency seems to be directly related to the high incidence of onychocryptosis in this population.

Hemorragia digestiva e insuficiencia hepática aguda por leptospirosis: una entidad que no debemos olvidar / Gastrointestinal bleeding and acute hepatic failure by leptospirosis: an entity that should not be forgotten

La leptospirosis es una enfermedad causada por la espiroqueta Leptospira. Se trata de una zoonosis de distribución mundial, con predominio en los trópicos. En España no es frecuente pero sí se observan casos en zonas más húmedas o con presencia de ríos, lagos o estanques, como son Cataluña, Andalucía o la Comunidad Valenciana, donde se relaciona con los arrozales. Los transmisores son múltiples animales como vacas o ratas, contagiándose el ser humano mediante contacto directo con estos animales o su orina, o bien de forma indirecta al consumir o estar en contacto con agua contaminada por la orina de éstos. Las manifestaciones clínicas son muy variables, siendo asintomática o poco sintomática en la mayoría de los pacientes. Aunque no ocurre siempre, la leptospirosis cursa con una primera fase con fiebre, mialgias, afectación renal o hemorragia de distintos órganos, seguida de una segunda fase con presencia de ictericia por afectación hepática. La enfermedad de Weil es una forma de leptospirosis grave caracterizada por afectación hepática con ictericia e insuficiencia renal aguda, asociada a una considerable mortalidad. El diagnóstico se basa en técnicas serológicas y detección de DNA mediante PCR. El tratamiento consta de medidas de soporte y antibioticoterapia. Presentamos un paciente con enfermedad de Weil y hemorragia digestiva por leptospirosis, con una evolución clínica fulminante, y hacemos hincapié en la necesidad de tener presente esta entidad, especialmente en ambientes epidemiológicos favorables como el de este paciente, con el fin de lograr un diagnóstico precoz.

Leptospirosis disease is caused by the spirochete Leptospira. It is a worldwide distribution zoonosis, with predominance in the tropics. In Spain, it is not frequent but some cases have been noticed especially in humid areas surrounded by rivers, lakes or ponds, such as Catalonia, Andalucia or the Valencian Community. It is transmitted by a variety of animals such as cows or rats, that are infected either by direct contact with these animals or their urine, or indirectly by consuming or being in contact with water contaminated by their urine. The clinical manifestations are very variable, being asymptomatic or not very symptomatic in most of the patients. Unusually, leptospirosis presents with a first phase with fever, myalgias, liver injury or different organs hemorrhage, followed by a second phase with the presence of jaundice due to hepatic failure. Weil's disease is a kind of severe leptospirosis characterized by hepatic failure with jaundice and acute renal failure, associated with high mortality rates. The diagnosis is based on serological techniques and DNA detection by PCR. The treatment consists of life support measures and antibiotic therapy. A patient with Weil's disease and leptospirosis digestive bleeding is presented, with a fulminant clinical course. In order to achieve an early diagnosis, the need to keep this entity in mind must be emphasized, especially in favorable epidemiological environments as the one of this patient.

Early neural cell death is an extensive, dynamic process in the embryonic chick and mouse retina.

Orchestrated proliferation, differentiation, and cell death contribute to the generation of the complex cytoarchitecture of the central nervous system, including that of the neuroretina. However, few studies have comprehensively compared the spatiotemporal patterns of these 3 processes, or their relative magnitudes. We performed a parallel study in embryonic chick and mouse retinas, focusing on the period during which the first neurons, the retinal ganglion cells (RGCs), are generated. The combination of in vivo BrdU incorporation, immunolabeling of retinal whole mounts for BrdU and for the neuronal markers Islet1/2 and ß III-tubulin, and TUNEL allowed for precise cell scoring and determination the spatiotemporal patterns of cell proliferation, differentiation, and death. As predicted, proliferation preceded differentiation. Cell death and differentiation overlapped to a considerable extent, although the magnitude of cell death exceeded that of neuronal differentiation. Precise quantification of the population of recently born RGCs, identified by BrdU and ß III-tubulin double labeling, combined with cell death inhibition using a pan-caspase inhibitor, revealed that apoptosis decreased this population by half shortly after birth. Taken together, our findings provide important insight into the relevance of cell death in neurogenesis.

Differential, age-dependent MEK-ERK and PI3K-Akt activation by insulin acting as a survival factor during embryonic retinal development.

Programmed cell death is a genuine developmental process of the nervous system, affecting not only projecting neurons but also proliferative neuroepithelial cells and young neuroblasts. The embryonic chick retina has been employed to correlate in vivo and in vitro studies on cell death regulation. We characterize here the role of two major signaling pathways, PI3K-Akt and MEK-ERK, in controlled retinal organotypic cultures from embryonic day 5 (E5) and E9, when cell death preferentially affects proliferating neuroepithelial cells and ganglion cell neurons, respectively. The relative density of programmed cell death in vivo was much higher in the proliferative and early neurogenic stages of retinal development (E3-E5) than during neuronal maturation and synaptogenesis (E8-E19). In organotypic cultures from E5 and E9 retinas, insulin, as the only growth factor added, was able to completely prevent cell death induced by growth factor deprivation. Insulin activated both the PI3K-Akt and the MEK-ERK pathways. Insulin survival effect, however, was differentially blocked at the two stages. At E5, the effect was blocked by MEK inhibitors, whereas at E9 it was blocked by PI3K inhibitors. The cells which were found to be dependent on insulin activation of the MEK-ERK pathway at E5 were mostly proliferative neuroepithelial cells. These observations support a remarkable specificity in the regulation of early neural cell death.