Combined small cell carcinoma of the sinonasal tract associated with syndrome of inappropriate secretion of antidiuretic hormone: A case report.

Combined small cell carcinoma (SmCC) and squamous cell carcinoma (SqCC) is a rare malignant neoplasm in the head and neck. This study presents the first reported case of combined SmCC and SqCC originating from the sinonasal tract accompanied by syndrome of inappropriate secretion of antidiuretic hormone (SIADH). An 80-year-old female presented with a four-week history of right nasal discharge, nasal obstruction and left neck swelling. Imaging studies revealed a tumorous lesion in the maxillary sinus encroaching upon the right nasal cavity and left cervical lymph node (LN) swelling. An incisional biopsy carried out from the right maxillary sinus and LNs resulted in a diagnosis of combined SmCC with SqCC, staged as T4aN2cM0. Clinical examination revealed a sustained increase of antidiuretic hormone, hyponatremia with urinary sodium increase, and serum hypo-osmosis, resulting in SIADH. Water restriction to <1,000 ml/day was effective in improving sodium and osmotic imbalance. Curative treatment for the tumor was not prescribed due to the poor condition of the patient. Palliative treatment was administered and the patient succumbed to cachexia five months after histological diagnosis. The presence of SIADH may have marked implications for the treatment and prognosis of this disease.

Motor dysfunction in cerebellar Purkinje cell-specific vesicular GABA transporter knockout mice.

γ-Aminobutyric acid (GABA) is a major inhibitory neurotransmitter in the adult mammalian central nervous system and plays modulatory roles in neural development. The vesicular GABA transporter (VGAT) is an essential molecule for GABAergic neurotransmission due to its role in vesicular GABA release. Cerebellar Purkinje cells (PCs) are GABAergic projection neurons that are indispensable for cerebellar function. To elucidate the significance of VGAT in cerebellar PCs, we generated and characterized PC-specific VGAT knockout (L7-VGAT) mice. VGAT mRNAs and proteins were specifically absent in the 40-week-old L7-VGAT PCs. The morphological characteristics, such as lamination and foliation of the cerebellar cortex, of the L7-VGAT mice were similar to those of the control littermate mice. Moreover, the protein expression levels and patterns of pre- (calbindin and parvalbumin) and postsynaptic (GABA-A receptor α1 subunit and gephyrin) molecules between the L7-VGAT and control mice were similar in the deep cerebellar nuclei that receive PC projections. However, the L7-VGAT mice performed poorly in the accelerating rotarod test and displayed ataxic gait in the footprint test. The L7-VGAT mice also exhibited severer ataxia as VGAT deficits progressed. These results suggest that VGAT in cerebellar PCs is not essential for the rough maintenance of cerebellar structure, but does play an important role in motor coordination. The L7-VGAT mice are a novel model of ataxia without PC degeneration, and would also be useful for studying the role of PCs in cognition and emotion.