Mortalidad y enfermedades asociadas al síndrome de Down en el primer año de vida: Experiencia de la Policlínica Interdisciplinaria de Atención al niño con síndrome de Down del Servicio de Recién Nacidos del Centro Hospitalario Pereira Rossell / Mortality and disease associated with Down syndrome in the first year of life

Introducción: la Policlínica Interdisciplinaria de Atención al Niño con síndrome de Down brinda asistencia desdeel nacimiento hasta el segundo año de vida.Objetivo: describir la mortalidad observada y las enfermedades asociadas diagnosticadas en el primer año devida en los niños con síndrome de Down atendidos en la policlínica.Material y métodos: niños con síndrome de Down nacidos o derivados al Servicio de Recién Nacidos del CentroHospitalario Pereira Rossell desde el 7 de enero de 2003 al 30 de abril del 2005.Resultados: se asistieron 45 niños. 22 madres eran mayores de 35 años (48,9%). En un caso se realizódiagnóstico prenatal (2,2%). Fallecieron ocho niños (17,8%). En 36 niños se observaron malformaciones asociadas (80,0%). Presentaron cardiopatía congénita 32 niños (71,1%), de los cuales requirieron tratamientoquirúrgico 11 (34,4%). Se diagnosticó hipotiroidismo congénito en un niño (2,2%). De los 37 niños quesobrevivieron al año se detectó hipotiroidismo entre los 6 meses y el año en 8 (21,6%).Conclusiones: la atención por un grupo interdisciplinario permite responder a los múltiples problemas queenfrentan estos niños y sus familias. Permitió un diagnóstico temprano de las enfermedades presentes en estospacientes. Se destaca la alta mortalidad, la alta incidencia de cardiopatía congénita e hipotiroidismo observado.

Introduction: an Interdisciplinary Center for the Attention of Children with Down syndrome provides services forchildren until the age of 2.Objective: describe the mortality incidence and the associated diseases during the first year of life in children withDown syndrome.Material and methods: children with Down syndrome born or derived to the Pereira Rossell Neonatology Servicefrom January 7, 2003 until April 30, 2005.Results: 45 children were assisted. 22 mothers (48,9%) were over 35 years old. Only in one case (2,2%) aprenatal diagnosis was done. 8 children died (17,8%). Associated malformations were observed in 36 children(80%). 32 children (71,1%) had congenital heart disease and 11 (34,4%) required surgery. One children (2,2%)had congenital hypothyroidism. From the 37 children alive after one year, eight had hypothyroidism.Conclusions: these children and families multiple problems are confronted in a better way by an interdisciplinarygroup. This allowed an earlier diagnosis of the different problems. There is a high mortality and a high incidence ofcardiac and thyroid problems.

Rate of freezing effect on the colour of frozen beef liver.

One problem that arises when freezing liver in plate freezers in the whitish colour acquired by the liver surface when subjected to high freezing rates. The purpose of this paper aims to establish optimum operating conditions for freezing beef liver pieces in a minimum time while maintaining an acceptable colour on the surface. Samples were subjected to different freezing rates and minimum surface freezing time was established in order to obtain an acceptable colour. This was quantified in terms of lightness using a surface colorimeter. Histological analysis of the samples showed that the size of the ice crystals formed on the contact surface with the coolant is the factor that determines the changes in colour as a result of diffused light reflection phenomena. On the basis of mathematical heat transfer models with simultaneous change of phase, the minimum characteristic surface freezing time was related to the process operating variables (initial temperature of the liver, coolant temperature, interfacial heat transfer resistance, thickness of the piece), and the optimum freezing conditions were determined, reducing total processing times to a minimum.

Basis for a method of characterization for quick frozen beef.

For better commercial development simple methods of quality control are needed to distinguish between quick frozen and normally frozen products. Usually the specifications for quick frozen meat have been limited to a description of the freezing process rather than to the establishment of quality standards which could be detected by tests on the product itself. In a previous paper a maximum in the weight of drip obtained on thawing was identified at local freezing times (-1°C to -7°C) of 17 min. The higher the freezing rate, the deeper the position of this maximum. Simultaneously, a computer model was developed to define the local freezing time and link it with an average freezing rate, through the simulation of heat transfer, during meat processing in plane freezers. On these bases a characterisation of quick frozen meat has been quantitatively developed in terms of the maximum position.

Freezing rate effects on the drip loss of frozen beef.

One of the quality parameters of frozen meat is the amount of exudate which arises during thawing. The amount of drip obtained by centrifugation under standard conditions, and the protein composition of the exudate, has been correlated for different thermal histories. The results obtained show that the amount of exudate varies in relation to the time that the sample needs to pass from -1°C to -7°C (characteristic freezing time). On the other hand, pH and concentration of proteins do not show significant differences between frozen and unfrozen samples. Similarly, neither one nor the other varies with the rate of freezing. The proteins were also analysed by electrophoresis in polyacrylamide gel. In this case, no differences were observed either between frozen samples and unfrozen ones or between samples which had been frozen at different rates. Hypotheses on the origin of cellular damage and alternatives which lead to the establishment of a standard of quality for quick frozen meat are presented in relation to the results obtained.

Relationship between heat transfer parameters and the characteristic damage variables for the freezing of beef.

One of the most suitable parameters for relating the freezing rate to the volume of drip produced during the thawing of meat is the characteristic time, defined as the time necessary to reduce the temperature of the sample from -1·1°C (initial freezing point in beef) to -7°C (80% of the water frozen). However, as the freezing of beef in factories takes place with important temperature gradients, distributions of these characteristic times must be expected along the pieces of frozen meat. In order to relate these characteristic time distributions to heat transfer parameters under industrial freezing conditions, a mathematical model which simulates the freezing of beef is developed in this paper. The model establishes the heat transfer equations with simultaneous change of phase, taking into account the dependence of the thermal properties with the ice content and considering the anisotropy of the thermal conductivity according to the direction of the fibres. Boundary conditions include the possibility of thermal resistances in the refrigerated interphase. The model developed was compared with laboratory experiments performed under factory freezing conditions and showed a satisfactory agreement between theory and experiment.

Weight loss prediction during meat chilling.

A lumped parameter model for computing weight losses during meat chilling is proposed. The model is independent of the shape of the piece of meat and allows the fraction of fat and bone to be taken into account. With this information a distinction between the heat transfer and the mass transfer areas can be established. Also provided is a correction factor which permits the existence of temperature gradients inside the meat to be taken into consideration. With the aid of the model the effect of the different operating variables on weight losses is analysed. The values predicted by the model show good agreement with experimental data obtained by other authors for the chilling of steers, cows and lambs under a wide range of operating conditions.

Dendritic growth of ice crystals during the freezing of beef.

The morphology adopted by ice in frozen tissues is accepted as one of the factors responsible for freezing damage. For this reason ice nucleation and growing mechanisms have been extensively studied. However, under the conditions used in the industry, where important temperature gradients exist, the classical analysis of nucleation and growth, depending on the supercooling, is complicated by the dendritic growth of crystals as well as by the possibility of the location of the ice crystal inside or outside the cells. In the present paper experiments which verify the existence of dendritic ice growth during the freezing of beef are described. The dendritic growth rate of ice in beef is measured as a function of the supercooling and an analysis of the expected mechanism, according to freezing conditions, is also provided.

A model for the thermal conductivity of frozen meat.

Even though extensive work on the experimental determination of the thermal conductivities of foodstuffs at different temperatures has been published, only a few predictive models for this important property have been developed. Calculation of freezing times in foods, such as meat, over the range from -1°C to -30°C, requires the use of mathematical models in which information on the thermal conductivity of partially frozen meat as a function of ice content in the tissue is provided. In the present paper a model for the thermal conductivity of meat as a function of temperature, which also accounts for its anisotropic properties, is proposed. Both directions, parallel and perpendicular to meat fibres, are considered and the model applies to unfrozen as well as to partially frozen meat. Results show good agreement with published experimental data obtained by a steady state method for different temperatures.