RESUMEN

Introduction: Adherence to the American Academy of Pediatrics clinical practice guidelines for screening and managing high blood pressure (BP) is low. This team sought to improve recognition and documentation of relevant diagnoses in patients aged 13-20 years who presented to general pediatric clinics. Methods: The primary outcome measure was the proportion of office visits for patients ages 13-20 with a BP ≥ 120/80 with a visit or problem list diagnosis of hypertension or elevated BP. Secondary measures included (1) the proportion of patients who had their BP measured in the right arm, (2) the proportion of patients who had a mid-arm circumference measurement recorded, and (3) the proportion of patients who had a second BP reading measured at the visit. Interventions addressed key drivers for evidence-based high BP screening: standard BP measurement, electronic health record clinical decision support, and clinical pathway adoption. Data were collected over a twenty-seven-month period and plotted using the Laney p' chart. Results: Provider documentation of elevated BP or hypertension improved from a baseline mean of 24% in April 2020 through January 2022 to 41% in February 2021 through June 2022. All secondary outcome measures also demonstrated significant improvement. Conclusions: This project demonstrates the feasibility of improving adherence to best practices of BP measurement in primary care clinics through education, acquisition of resources, and implementation of electronic health record flags for abnormal values.

RESUMEN

BACKGROUND: Food insecurity (FI), limited availability of or access to nutritional foods, is linked to poor child/caregiver health. We examined FI in food-allergic and non-food-allergic children to determine whether dietary limitations associated with food allergy increases risk of FI. METHODS: Food-allergic and non-food-allergic children (1-17 years) were recruited from Arkansas Children's Hospital allergy/asthma clinics. The USDA Food Security Survey, the Newest Vital Sign Health Literacy (HL) questionnaire, and the Food Allergy Impact Scale QOL survey were administered. Logistic regression and analysis of covariance models were utilized for data analysis. RESULTS: Subjects (n = 650) included 325 food-allergic and 325 non-food-allergic children. Overall rate of FI was 21.5% (food allergic 22.2% and non-food allergic 20.9%) with no significant difference in the prevalence of FI between groups (OR = 1.30; 95% CI 0.86-1.96; P = 0.21). FI was increased in households of children with both milk and egg allergy when compared to those without food allergy and those with single food allergy (OR = 2.5; 95% CI 1.4-4.6; P = 0.003). Mean HL rates were higher in the food-secure vs food-insecure groups (mean diff = 0.31; 95% CI 0.03-0.59; P = 0.03). Among food-allergic children, QOL was better in the food-secure vs food-insecure group (mean diff = 0.61; 95% CI 0.002-1.23; P = 0.049). CONCLUSION: Food allergy to milk and egg was associated with increased risk of household FI. Food-insecure participants had lower HL than their food-secure counterparts. Further work is needed to define risks associated with FI among food-allergic children to improve screening and management strategies.

Asunto(s)

Hipersensibilidad a los Alimentos/complicaciones , Abastecimiento de Alimentos/estadística & datos numéricos , Alfabetización en Salud/estadística & datos numéricos , Adolescente , Arkansas , Niño , Preescolar , Estudios Transversales , Femenino , Humanos , Lactante , Masculino , Prevalencia , Calidad de Vida , Factores de Riesgo , Encuestas y Cuestionarios , Atención Terciaria de Salud/estadística & datos numéricos

RESUMEN

129 Wada procedures were reviewed to examine the suitability of propofol (n=54) as a replacement to amobarbital (n=75) for use as an anaesthetic in the Wada test. Suitability was considered with respect to length of hemiplegia induced, the frequency of side effects and patient memory scores. Data was retrospectively collected from records of patients who had undergone the Wada procedure between 2004 and 2009 in Beaumont Hospital, Dublin. No significant differences were found between the two drugs on any of the measures. The results suggest that propofol represents a suitable alternative to amobarbital for use in the Wada procedure.

Asunto(s)

Amobarbital/farmacología , Memoria/efectos de los fármacos , Pruebas Neuropsicológicas , Propofol/farmacología , Adolescente , Adulto , Amobarbital/efectos adversos , Femenino , Humanos , Masculino , Persona de Mediana Edad , Propofol/efectos adversos , Estudios Retrospectivos , Adulto Joven

RESUMEN

The surface O-antigen polymers of gram-negative bacteria exhibit a modal length distribution that depends on dedicated chain length regulator periplasmic proteins (polysaccharide co-polymerases, PCPs) anchored in the inner membrane by two transmembrane helices. In an attempt to determine whether structural changes underlie the O-antigen modal length specification, we have determined the crystal structures of several closely related PCPs, namely two chimeric PCP-1 family members solved at 1.6 and 2.8 Å and a wild-type PCP-1 from Shigella flexneri solved at 2.8 Å. The chimeric proteins form circular octamers, whereas the wild-type WzzB from S. flexneri was found to be an open trimer. We also present the structure of a Wzz(FepE) mutant, which exhibits severe attenuation in its ability to produce very long O-antigen polymers. Our findings suggest that the differences in the modal length distribution depend primarily on the surface-exposed amino acids in specific regions rather than on the differences in the oligomeric state of the PCP protomers.

Asunto(s)

Proteínas Bacterianas/metabolismo , Proteínas de Escherichia coli/metabolismo , Antígenos O/metabolismo , Proteínas Periplasmáticas/metabolismo , Secuencia de Aminoácidos , Proteínas Bacterianas/química , Proteínas Bacterianas/genética , Cristalografía por Rayos X , Escherichia coli/genética , Escherichia coli/metabolismo , Proteínas de Escherichia coli/química , Proteínas de Escherichia coli/genética , Modelos Moleculares , Datos de Secuencia Molecular , Proteínas Periplasmáticas/química , Proteínas Periplasmáticas/genética , Multimerización de Proteína , Estructura Secundaria de Proteína , Estructura Terciaria de Proteína , Homología de Secuencia de Aminoácido , Shigella flexneri/genética , Shigella flexneri/metabolismo

Asunto(s)

Dolor en el Pecho/diagnóstico por imagen , Dolor en el Pecho/etiología , Exostosis/complicaciones , Exostosis/diagnóstico por imagen , Factores de Edad , Niño , Humanos , Masculino , Tomografía Computarizada por Rayos X

RESUMEN

OBJECTIVE: Olfactory neuroblastoma (ONB) is an uncommon malignant tumor of the sinonasal tract and has a wide histologic differential diagnosis that includes other small round blue cell tumors (SRBCTs). Even with the use of immunohistochemistry (IHC), the correct diagnosis may be difficult, especially in small biopsies. The purpose of this study is to determine the usefulness of calretinin and p63 as an aid to distinguish ONB from other sinonasal SRBCTs. METHODS: IHC staining for calretinin and p63 was performed on 21 specimens diagnosed as ONB and on 42 other sinonasal SRBCTs. Specimens were retrieved from the files of the QEII HSC, Halifax and UHN, Toronto. RESULTS: All but 1 ONB (20 of 21) showed calretinin staining, with 15 of 21 showing staining in >75% of the tumor area and 18 of 21 showing moderate-to-strong staining intensity. Only pituitary adenomas (3 of 3) and a single case of small cell carcinoma, neuroendocrine type (1 of 2), showed a similar staining pattern. None of the ONBs showed staining for p63. P63 was positive in all cases of nonkeratinizing squamous cell carcinoma (2 of 2) and in single cases of mantle cell lymphoma (1 of 1) and poorly differentiated neuroendocrine carcinoma (1 of 1); however, it inconsistently stained diffuse large B-cell lymphoma (4 of 5), extranodal NK/T-cell lymphoma, nasal type (1 of 4), sinonasal undifferentiated carcinoma (1 of 6), and Ewing sarcoma/primitive neuroectodermal tumor (2 of 6). CONCLUSIONS: Calretinin appears to be a useful marker to distinguish ONBs from other SRBCTs of the sinonasal tract, particularly when staining is moderate/strong and extensive. The calretinin-positive, p63-negative phenotype is fairly specific for ONB. The addition of these 2 IHC stains may aid in the diagnosis of sinonasal SRBCTs that are poorly differentiated, have inconclusive conventional IHC, or are found in small biopsies.

Asunto(s)

Biomarcadores de Tumor/análisis , Estesioneuroblastoma Olfatorio/diagnóstico , Neoplasias Nasales/diagnóstico , Proteína G de Unión al Calcio S100/biosíntesis , Adulto , Anciano , Calbindina 2 , Diagnóstico Diferencial , Estesioneuroblastoma Olfatorio/metabolismo , Estesioneuroblastoma Olfatorio/patología , Femenino , Humanos , Inmunohistoquímica , Masculino , Proteínas de la Membrana/biosíntesis , Persona de Mediana Edad , Cavidad Nasal/patología , Neoplasias Nasales/metabolismo , Neoplasias Nasales/patología , Adulto Joven

RESUMEN

Scaffold and adaptor proteins provide means for the spatial organization of signaling cascades. MP1 is a scaffold protein in the RAF/MEK/ERK pathway and together with p14 forms a heterodimer that was shown to be responsible for localization of MEK to the late endosomal compartment. However, the mechanism by which MP1/p14 tethers MEK to the endosomal membrane was not resolved. Recently, an adaptor protein p18 was identified as a binding partner of MP1/p14. p18 is attached to the endosomal surface by myristoyl and palmitoyl groups located at the N-terminus of the protein and tethers the signaling complex to the cytoplasmic surface of late endosomes. p18 expressed in E. coli is retained in inclusion bodies, and we developed a protocol to refold it from the denatured state. Coexpression of p18 with MP1/p14 leads to a soluble protein complex. We examined the interaction of p18 with the MP1/p14 constitutive heterodimer. We cloned various constructs of p18 and characterized their behavior and interactions with MP1/p14 in vitro using SEC and pull-down assays. We determined that the refolded p18 is a monomer in solution with molten globule characteristics. Its binding to MP1/p14 promotes folding and ordering. We also identified a proteolytically stable fragment of p18 and showed that it binds to MP1/p14 with similar affinity to the full-length construct and determined an apparent dissociation constant in the low micromolar range for the interaction. Finally, we show that the ∼60 C-terminal residues of p18 are not required for in vitro interaction with MP1/p14 heterodimer, in contrast to previously reported findings showing that truncation of 41 C-terminal residues of p18 prevents endosomal localization of MP1/p14.

Asunto(s)

Proteínas Adaptadoras Transductoras de Señales/química , Proteínas Adaptadoras Transductoras de Señales/metabolismo , Proteínas/metabolismo , Animales , Calorimetría/métodos , Dicroismo Circular , Clonación Molecular , Citoplasma/metabolismo , Dimerización , Escherichia coli/enzimología , Quinasas MAP Reguladas por Señal Extracelular/metabolismo , Eliminación de Gen , Ratones , Mutación , Desnaturalización Proteica , Pliegue de Proteína

RESUMEN

Involvement of the falx cerebri in infants with stage 4 neuroblastoma is thought to be rare. The falx is derived from the neural crest and thus may be a location for primary neuroblastoma. Its propensity for metastasis is unknown. Management of neuroblastoma in this location is potentially challenging. We describe two children less than 18 months of age who were successfully managed with chemotherapy alone (without radiation or surgery) for falx involvement with neuroblastoma.

Asunto(s)

Neoplasias de las Glándulas Suprarrenales/patología , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Duramadre/patología , Neoplasias Meníngeas/secundario , Neuroblastoma/secundario , Neoplasias de las Glándulas Suprarrenales/tratamiento farmacológico , Neoplasias de las Glándulas Suprarrenales/cirugía , Adrenalectomía , Carboplatino/administración & dosificación , Linaje de la Célula , Ciclofosfamida/administración & dosificación , Doxorrubicina/administración & dosificación , Etopósido/administración & dosificación , Femenino , Humanos , Lactante , Recién Nacido , Masculino , Neoplasias Meníngeas/tratamiento farmacológico , Factor de Transcripción Asociado a Microftalmía/genética , Estadificación de Neoplasias , Cresta Neural , Neuroblastoma/tratamiento farmacológico , Neuroblastoma/genética , Neuroblastoma/patología , Neuroblastoma/cirugía , Venas Pulmonares/anomalías , Inducción de Remisión , Neoplasias Cutáneas/tratamiento farmacológico , Neoplasias Cutáneas/secundario , Síndrome de Waardenburg/complicaciones , Síndrome de Waardenburg/genética

RESUMEN

The densities of states are evaluated for very short chain molecules made up of overlapping monomers, using a model which has previously been shown to produce helical structure. The results of numerical calculations are presented for tetramers and pentamers. We show that these models demonstrate behaviors relevant to the behaviors seen in longer, helix-forming chains, particularly "magic numbers" of the overlap parameter, where the derivatives of the densities of states change discontinuously, and a region of bimodal energy probability distributions, reminiscent of a first-order phase transition in a bulk system.

Asunto(s)

Antiasmáticos/uso terapéutico , Asma , Asma/clasificación , Asma/diagnóstico , Asma/terapia , Niño , Humanos , Actividad Motora , Guías de Práctica Clínica como Asunto , Pruebas de Función Respiratoria

Asunto(s)

Asma/terapia , Administración Oral , Adolescente , Corticoesteroides/administración & dosificación , Corticoesteroides/uso terapéutico , Adulto , Factores de Edad , Asma/clasificación , Asma/diagnóstico , Broncodilatadores/administración & dosificación , Broncodilatadores/uso terapéutico , Estudios de Seguimiento , Humanos , Guías de Práctica Clínica como Asunto , Pruebas de Función Respiratoria , Terapia Respiratoria , Índice de Severidad de la Enfermedad , Espirometría , Encuestas y Cuestionarios , Factores de Tiempo , Resultado del Tratamiento

RESUMEN

OBJECTIVE: To examine the relationship of body mass index (BMI) and asthma indicators on children with asthma in a Head Start (HS) program. METHODS: In this cross-sectional study (November 18, 2000, to December 12, 2003) of children aged 3 to 5 years with asthma, we compared the BMI data of HS asthmatic patients (n = 213) with the data of peer control subjects from a sample (n = 816) of the National Health and Nutrition Examination Survey aged 3 to 5 years and with children in prekindergarten in Arkansas public schools (n = 1,024). Parental reports of asthma symptoms, health care use, medication use, school days missed, and quality of life were used as indicators of asthma morbidity. Categorical analysis and chi2 tests were performed to examine the relationship between BMI and asthma morbidity. RESULTS: The prevalence of overweight (> or =95th percentile) was significantly higher in HS children with asthma compared with the National Health and Nutrition Examination Survey children (P < .001) and Arkansas prekindergarten children (P = .05). Compared with HS asthmatic children with a BMI less than the 85th percentile, HS asthmatic patients with a BMI of the 85th percentile or greater reported significantly more school days missed (P = .02), lifetime hospitalizations (P = .04), emergency department visits (P = .02), and activity limitations (P = .03) and fewer oral corticosteroid bursts (P = .04). There was also a trend for more daytime symptoms (P = .05) and lower quality of life (P = .06). No differences were observed in rescue (P = .28) or controller (P = .47) medications, environmental tobacco smoke exposure (P = .47), positive allergy test results (P = .85), and nighttime symptoms (P > .99). CONCLUSIONS: Having an increased BMI was associated with more asthma morbidity in this group of HS asthmatic patients. Despite the lack of a clear explanation for the link between asthma and BMI, our data suggest that an increased BMI significantly affects the well-being of young asthmatic patients and should be further addressed.

Asunto(s)

Asma/prevención & control , Índice de Masa Corporal , Intervención Educativa Precoz/métodos , Negro o Afroamericano/estadística & datos numéricos , Asma/etnología , Asma/fisiopatología , Preescolar , Estudios Transversales , Femenino , Indicadores de Salud , Humanos , Masculino , Encuestas y Cuestionarios

RESUMEN

We have studied the competition between helix formation and aggregation for a simple polymer model. We present simulation results for a system of two such polymers, examining the potential of mean force, the balance between intermolecular and intramolecular interactions, and the promotion or disruption of secondary structure brought on by the proximity of the two molecules. In particular, we demonstrate that proximity between two such molecules can stabilize secondary structure. However, for this model, observed secondary structure is not stable enough to prevent collapse of the system into an unstructured globule.

Asunto(s)

Modelos Químicos , Modelos Moleculares , Polímeros/química , Proteínas/química , Proteínas/ultraestructura , Sitios de Unión , Simulación por Computador , Dimerización , Complejos Multiproteicos/química , Complejos Multiproteicos/ultraestructura , Unión Proteica , Conformación Proteica

RESUMEN

This population-based case-finding study sought to determine asthma prevalence and characterize disease severity and burden among school-aged children in the Little Rock School District. Asthma cases were identified by validated algorithm and parental report of asthma diagnosis. The overall response rate was low. Among schools with greater than 50% response rate, prevalence of physician-diagnosed asthma was comparable to other studies in public school settings. Prevalence of symptoms in cases identified as current is suggestive of poor asthma control. Improved systems for case identification of children with asthma are needed in schools. Efforts should focus on strategies to improve asthma control.

Asunto(s)

Asma/epidemiología , Manejo de Caso/estadística & datos numéricos , Costo de Enfermedad , Vigilancia de la Población , Servicios de Enfermería Escolar/estadística & datos numéricos , Adolescente , Algoritmos , Arkansas/epidemiología , Asma/diagnóstico , Asma/terapia , Niño , Preescolar , Estudios Transversales , Humanos , Padres , Prevalencia , Índice de Severidad de la Enfermedad , Encuestas y Cuestionarios

RESUMEN

BACKGROUND: Children with poorly controlled asthma are at high risk of airway remodeling, sleep disruption, school absenteeism, and limited participation in activities. OBJECTIVE: To determine asthma prevalence and characterize disease severity and burden in school-aged children. METHOD: A case-finding study was conducted via a multiple-choice questionnaire and asthma algorithm. Items used for analysis include physician diagnosis of asthma, symptom severity, and health care utilization. The chi2 test was used to determine the significance of differences among cases. Logistic regression was used to evaluate the association of patient factors and asthma indicators. RESULTS: Of the 5,417 children surveyed, 1,341 (25%) were classified as being at risk of asthma. Of these asthma cases, 55% were positive by diagnosis and algorithm (active), 10% were positive per algorithm alone (suspected), and 35% were positive per diagnosis alone (nonactive). Only 14% of all asthma cases reported experiencing no respiratory symptoms (< 1% active, 2% suspected, and 40% nonactive) compared with 75% of noncases. Also, 75% of noncases reported never missing school compared with 19%, 33%, and 54% of active, suspected, and nonactive asthma cases. African American race, Medicaid enrollment, and male sex were independent predictors of asthma risk. Similarly, African American race, Medicaid enrollment, age, and persistent asthma were independent predictors of emergency department use among asthma cases. DISCUSSION: Prevalence of active symptoms suggestive of poor asthma control was extremely high among urban, minority children enrolled in Arkansas' largest public school district. Poor asthma control greatly affects quality of life, including school attendance and performance. Interventions should raise expectations and emphasize the importance of achieving asthma control.

Asunto(s)

Asma/epidemiología , Negro o Afroamericano/estadística & datos numéricos , Población Urbana/estadística & datos numéricos , Adolescente , Arkansas/epidemiología , Arkansas/etnología , Niño , Preescolar , Servicio de Urgencia en Hospital/estadística & datos numéricos , Femenino , Humanos , Masculino , Medicaid , Pobreza , Prevalencia , Índice de Severidad de la Enfermedad , Factores Sexuales , Encuestas y Cuestionarios , Salud Urbana/estadística & datos numéricos

RESUMEN

We present Monte Carlo simulation results for square-well homopolymers at a series of bond lengths. Although the model contains only isotropic pairwise interactions, under appropriate conditions this system shows spontaneous chiral symmetry breaking, where the chain exists in either a left- or a right-handed helical structure. We investigate how this behavior depends upon the ratio between bond length and monomer radius.

Asunto(s)

Modelos Químicos , Polímeros/química , Simulación por Computador , ADN/química , Conformación Molecular , Método de Montecarlo , Conformación de Ácido Nucleico , Ácidos Nucleicos/química , Conformación Proteica , Proteínas/química

RESUMEN

Protein-nucleic acid interactions exhibit varying degrees of specificity. Relatively high affinity, sequence-specific interactions, can be studied with structure determination, but lower affinity, non-specific interactions are also of biological importance. We report simulations that predict the population of nucleic acid paths around protein surfaces, and give binding constant differences for changes in the protein scaffold. The method is applied to the non-specific component of interactions between eIF4Es and messenger RNAs that are bound tightly at the cap site. Adding a fragment of eIF4G to the system changes both the population of mRNA paths and the protein-mRNA binding affinity, suggesting a potential role for non-specific interactions in modulating translational properties. Generally, the free energy simulation technique could work in harness with characterized tethering points to extend analysis of nucleic acid conformation, and its modulation by protein scaffolds.

Asunto(s)

Factor 4E Eucariótico de Iniciación/química , Caperuzas de ARN/química , Simulación por Computador , Factor 4E Eucariótico de Iniciación/metabolismo , Modelos Moleculares , Método de Montecarlo , Unión Proteica , Caperuzas de ARN/metabolismo , ARN Mensajero/química , ARN Mensajero/metabolismo , Proteínas de Schizosaccharomyces pombe/química , Proteínas de Schizosaccharomyces pombe/metabolismo

RESUMEN

A study was conducted to determine the presence of resveratrol, pterostilbene, and piceatannol in Vaccinium berries. Samples representing selections and cultivars of 10 species from Mississippi, North Carolina, Oregon, and Canada were analyzed by gas chromatography/mass spectrometry. Resveratrol was found in Vaccinium angustifolium (lowbush blueberry), Vaccinium arboretum (sparkleberry), Vaccinium ashei (rabbiteye blueberry), Vaccinium corymbosum (highbush blueberry), Vaccinium elliottii (Elliott's blueberry), Vaccinium macrocarpon (cranberry), Vaccinium myrtillus (bilberry), Vaccinium stamineum (deerberry), Vaccinium vitis-ideae var. vitis-ideae (lingonberry), and Vaccinium vitis-ideae var. minor (partridgeberry) at levels between 7 and 5884 ng/g dry sample. Lingonberry was found to have the highest content, 5884 ng/g dry sample, comparable to that found in grapes, 6471 ng/g dry sample. Pterostilbene was found in two cultivars of V. ashei and in V. stamineum at levels of 99-520 ng/g dry sample. Piceatannol was found in V. corymbosum and V. stamineum at levels of 138-422 ng/g dry sample. These naturally occurring stilbenes, known to be strong antioxidants and to have cancer chemopreventive activities, will add to the purported health benefits derived from the consumption of these small fruits.

Asunto(s)

Frutas/química , Fenoles/análisis , Estilbenos/análisis , Vaccinium/química , Antioxidantes/análisis , Resveratrol , Especificidad de la Especie

RESUMEN

Plants are proven sources of useful anti-tumor and chemopreventative compounds. Hence, identification of phytochemicals useful in dietary prevention and intervention of cancer is of paramount importance. The initial step in the formation of cancer is damage to the genome of a somatic cell producing a mutation in an oncogene or a tumor-suppressor gene. Fresh juices and organic solvent extracts from the fruits of strawberry, blueberry, and raspberry were evaluated for their ability to inhibit the production of mutations by the direct-acting mutagen methyl methanesulfonate and the metabolically activated carcinogen benzo[a]pyrene. Juice from strawberry, blueberry, and raspberry fruit significantly inhibited mutagenesis caused by both carcinogens. Ethanol extracts from freeze-dried fruits of strawberry cultivars (Sweet Charlie and Carlsbad) and blueberry cultivars (Tifblue and Premier) were also tested. Of these, the hydrolyzable tannin-containing fraction from Sweet Charlie strawberries was most effective at inhibiting mutations.

Asunto(s)

Antimutagênicos/farmacología , Benzo(a)pireno/antagonistas & inhibidores , Frutas/química , Metilmetanosulfonato/antagonistas & inhibidores , Extractos Vegetales/farmacología , Técnicas In Vitro , Pruebas de Mutagenicidad/métodos

RESUMEN

We report extensive simulation studies of phase behavior in single component systems of particles interacting via a core-softened interparticle potential. Two recently proposed examples of such potentials are considered; one in which the hard core exhibits a shoulder [Sadr-Lahijany et al., Phys. Rev. Lett. 81, 4895 (1998)], and the other in which the softening takes the form of a linear ramp [Jagla, Phys. Rev. E 63, 061501 (2001)]. Using a combination of state-of-the-art Monte Carlo methods, we obtain the gas, liquid, and solid phase behavior of the shoulder model in two dimensions. We then focus on the thermodynamic anomalies of the liquid phase, namely, maxima in the density and compressibility as a function of temperature. Analysis of the finite-size behavior of these maxima suggests that, rather than stemming from a metastable liquid-liquid critical point, as previously supposed, they are actually induced by the quasicontinuous nature of the two dimensional freezing transition. For the ramp model in three dimensions, we confirm the existence of a stable liquid-liquid ("second") critical point occurring at higher pressure and lower temperature than the liquid-gas critical point. Both these critical points and portions of their associated coexistence curves are located to high precision. In contrast to the shoulder model, the observed thermodynamic anomalies of this model are found to be authentic, i.e., they are not engendered by an incipient new phase. We trace the locus of density and compressibility maxima, the former of which appears to terminate close to the second critical point.