Input-dependent regulation of excitability controls dendritic maturation in somatosensory thalamocortical neurons.

Input from the sensory organs is required to pattern neurons into topographical maps during development. Dendritic complexity critically determines this patterning process; yet, how signals from the periphery act to control dendritic maturation is unclear. Here, using genetic and surgical manipulations of sensory input in mouse somatosensory thalamocortical neurons, we show that membrane excitability is a critical component of dendritic development. Using a combination of genetic approaches, we find that ablation of N-methyl-D-aspartate (NMDA) receptors during postnatal development leads to epigenetic repression of Kv1.1-type potassium channels, increased excitability, and impaired dendritic maturation. Lesions to whisker input pathways had similar effects. Overexpression of Kv1.1 was sufficient to enable dendritic maturation in the absence of sensory input. Thus, Kv1.1 acts to tune neuronal excitability and maintain it within a physiological range, allowing dendritic maturation to proceed. Together, these results reveal an input-dependent control over neuronal excitability and dendritic complexity in the development and plasticity of sensory pathways.

Cadherin expression in the somatosensory cortex: evidence for a combinatorial molecular code at the single-cell level.

Cadherin superfamily genes play a role in a wide variety of developmental processes and mature functions of the vertebrate brain. In the present study, we mapped in situ the expression pattern of five classic cadherins (Cdh4, Cdh6, Cdh7, Cdh8, Cdh11) and eight δ-protocadherins (Pcdh1, Pcdh7, Pcdh8, Pcdh9, Pcdh10, Pcdh11, Pcdh17 and Pcdh19) in the primary somatosensory cortex of the adult mouse. All of these cadherins show layer-specific expression profiles in primary somatosensory cortex. Some cadherins (for example, Cdh4, Cdh7, Pcdh8) mark subsets of cells within a given lamina, while other cadherins (Cdh11 and Pcdh10) are expressed more widely in multiple layers. Results from tyramide-based double-fluorescence in situ hybridization (FISH) provide evidence that most single neurons express more than one cadherin in a combinatorial fashion in all layers of cerebral cortex. This combinatorial code is rather comprehensive because pairwise expression of cadherins can assume any type of combination (complementarity, partial or complete overlap, subset-specific expression, cell-size specific expression, etc.). We propose that the combinatorial expression of multiple cadherin genes contributes to the molecular specification of the vast complexity of neurons in cerebral cortex.

Proptosis: a rare presentation of metastatic renal cell carcinoma.

We present a case of a middle-aged man who was incidentally found to have right renal solid mass while investigating for his left eye proptosis. Computerised tomography (CT) scan confirmed the diagnosis of renal cell carcinoma and the tumour was successfully excised via open surgery. The histopathology examination revealed the 10x7x8 cm mass to be a clear cell type renal cell carcinoma. The rare presentation of this metastatic renal cell carcinoma, its diagnosis and management will be discussed.

Expression of classic cadherins and delta-protocadherins in the developing ferret retina.

BACKGROUND: Cadherins are a superfamily of calcium-dependent adhesion molecules that play multiple roles in morphogenesis, including proliferation, migration, differentiation and cell-cell recognition. The subgroups of classic cadherins and delta-protocadherins are involved in processes of neural development, such as neurite outgrowth, pathfinding, target recognition, synaptogenesis as well as synaptic plasticity. We mapped the expression of 7 classic cadherins (CDH4, CDH6, CDH7, CDH8, CDH11, CDH14, CDH20) and 8 delta-protocadherins (PCDH1, PCDH7, PCDH8, PCDH9, PCDH10, PCDH11, PCDH17, PCDH18) at representative stages of retinal development and in the mature retina of the ferret by in situ hybridization. RESULTS: All cadherins investigated by us are expressed differentially by restricted populations of retinal cells during specific periods of the ferret retinogenesis. For example, during embryonic development, some cadherins are exclusively expressed in the outer, proliferative zone of the neuroblast layer, whereas other cadherins mark the prospective ganglion cell layer or cells in the prospective inner nuclear layer. These expression patterns anticipate histogenetic changes that become visible in Nissl or nuclear stainings at later stages. In parallel to the ongoing development of retinal circuits, cadherin expression becomes restricted to specific subpopulations of retinal cell types, especially of ganglion cells, which express most of the investigated cadherins until adulthood. A comparison to previous results in chicken and mouse reveals overall conserved expression patterns of some cadherins but also species differences. CONCLUSIONS: The spatiotemporally restricted expression patterns of 7 classic cadherins and 8 delta-protocadherins indicate that cadherins provide a combinatorial adhesive code that specifies developing retinal cell populations and intraretinal as well as retinofugal neural circuits in the developing ferret retina.

MR venography in cerebral venous sinus thrombosis.

A case of left transverse and sigmoid sinus thrombosis in a 60 years female is reported. The diagnosis was confirmed on MRI with MR venography.

Cholelithiasis in thalassaemia major.

The incidence of gall stones in thalassaemia is less than that in sickle cell anaemia or hereditary spherocytosis. With adequate blood transfusions, the incidence is as low as 2%. There are not many reports on cholelithiasis in thalassaemia. A case of 24-year-old female with thalassaemia major and gall stone is reported here.

Virtual bronchoscopy in carcinoma of lung.

A 55 years female presented with a malignant pleural effusion. Post-paracentesis, a lobular mass was seen which was biopsied after virtual bronchoscopy.

Ossification of posterior longitudinal ligament causing cervical cord compression.

Ossification of the posterior longitudinal ligament (OPLL) is an uncommon cause of compressive myelopathy outside Japan. A case of cervical cord compression in a female whose MRI showed OPLL is reported. T2 weighted MRI images are the most effective to evaluate both spinal cord compression due to ossification and abnormal signal intensity of the cord. OPLL should be included in the differential diagnosis of cervical radiculomyelopathy.

Acute disseminated encehalomyelitis with typhoid fever.

A 45 year old male came with fever, headache, altered sensorium pallor and lower gastrointestinal bleeding. Laboratory investigations confirmed typhoid fever. Magnetic resonance imaging (MRI) was suggestive of acute disseminated encephalomyelitis.