A hypomorphic Cbx3 allele causes prenatal growth restriction and perinatal energy homeostasis defects

Mammals have three HP1 protein isotypes HP1β (CBX1), HP1γ (CBX3) and HP1α (CBX5) that are encoded by the corresponding genes Cbx1, Cbx3 and Cbx5. Recent work has shown that reduction of CBX3 protein in homozygotes for a hypomorphic allele (Cbx3 hypo) causes a severe postnatal mortality with around 99% of the homozygotes dying before weaning. It is not known what the causes of the postnatal mortality are. Here we show that Cbx3 hypo/hypo conceptuses are significantly reduced in size and the placentas exhibit a haplo-insufficiency. Late gestation Cbx3 hypo/hypo placentas have reduced mRNA transcripts for genes involved in growth regulation, amino acid and glucose transport. Blood vessels within the Cbx3 hypo/hypo placental labyrinth are narrower than wild-type. Newborn Cbx3 hypo/hypo pups are hypoglycemic, the livers are depleted of glycogen reserves and there is almost complete loss of stored lipid in brown adipose tissue (BAT). There is a 10-fold reduction in expression of the BAT-specific Ucp1 gene, whose product is responsible for non-shivering themogenesis. We suggest that it is the small size of the Cbx3 hypo/hypo neonates, a likely consequence of placental growth and transport defects, combined with a possible inability to thermoregulate that causes the severe postnatal mortality

Hipocalcemia e hipoparatireoidismo clínico após tireoidectomia total

OBJETIVO: O hipoparatireoidismo que se sucede à tireoidectomia total é uma complicação relativamente freqüente, porém, em geral, assintomática. O presente estudo foi realizado a fim de correlacionar níveis séricos pós operatórios de cálcio com sinais e sintomas de hipocalcemia. MÉTODO: Cinqüenta e sete pacientes submetidos à tireoidectomia total foram estudados retrospectivamente na Disciplina de Cirurgia de Cabeça e Pescoço do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo. A dosagem sérica de cálcio, total ou ionizado,foi correlacionado com a presença, ou não, de sinais e sintomas de hipocalcemia, no pós-operatório imediato e tardio. RESULTADOS: A hipocalcemia precoce ocorreu em 37% dos casos e em 18% na fase tardia. Após seis meses da cirurgia, 50% dos pacientes sintomáticos não eram hipocalcêmicos e do total de hipocalcêmicos 57% eram assintomáticos. CONCLUSÕES: A avaliação clínica exclusiva pós-operatória não se mostrou confiável para o diagnóstico de hipocalcemia. A dosagem de cálcio deve ser feita como rotina após tireoidectomias totais

Multiphoton excitation microscopy for the reconstructionand analysis of single neuron morphology

Neurons are the main cellular components of the circuits of the central nervous system (CNS). The dendritic and axonal morphology of individual neurons display marked variability between neurons in different regions of the CNS, and there is evidence that the morphology of a neuron has a strong impact on its function. For studies of structure-function relationships of specific types of neurons, it is important to visualize and quantify the complete neuronal morphology. In addition, realistic and detailed morphological reconstruction is essential for developing compartmental models that can be used for studying neuronal computation and signal processing. Here we describe in detail how multiphoton excitation (MPE) microscopy of dye-filled neurons can be used for visualization and imaging of neuronal morphology, followed by a workflow with digital deconvolution and manual or semiautomatic morphological reconstruction. The specific advantages of MPE structural imaging are low phototoxicity, the ease with which it can be combined with parallel physiological measurements from the same neurons, and the elimination of tissue post-processing and fixation-related artifacts. Because manual morphological reconstruction can be very time-consuming, this chapter also includes a detailed, step-by-step description of a workflow for semiautomatic morphological reconstruction (using freely available software developed in our laboratory), exemplified by reconstruction of a retinal amacrine cell (AII)