Neurokinin 1 receptor and relative abundance of the short and long isoforms in the human brain

Substance P exerts its various biochemical effects mainly via interactions through neurokinin-1 receptors (NK1). Recently, the NK1 receptor has attracted considerable interest for its possible role in a variety of psychiatric disorders including depression and anxiety. However, little is known regarding the anatomical distribution of NK1 in the human central nervous system (CNS). Riboprobe in situ hybridization, quantitative PCR and in vitro autoradiography were performed. Highest NK1 mRNA levels were localized in the locus coeruleus and ventral striatum, while moderate hybridization signals were observed in the cerebral cortex (most abundant in the visual cortex), hippocampus and different amygdaloid nuclei. Very low levels of the NK1 mRNA were detected in the cerebellum and thalamus. In view of the existence of a long and short isoform of the NK1 receptor, it was of interest to assess whether there was a differential distribution of the two splice variants in the human CNS and peripheral tissues. A quantitative TaqMan PCR analysis showed that the long NK1 isoform was the most prevalent throughout the human brain, while in peripheral tissues the truncated form was the most represented. 3H-Substance P autoradiography revealed a good correlation between receptor binding sites and NK1 mRNA expression throughout the brain, with the highest levels of binding in the locus coeruleus. These results provide the anatomical evidence that the NK1 receptors have a strong association with neuronal systems relevant to mood regulation and stress in the human brain, but do not suggest a region-specific role of the two isoforms in the CNS.     

Radiology of the orbital apex

The orbital apex, formed by the superior orbital fissure and optic canal, is the cross-road between the orbit and the intracranial structures. Pathological processes may extend intracranially via the superior orbital fissure and vice versa. In addition to intrinsic soft tissue lesions, various pathological processes may involve the surrounding osseous anatomy. Malignant lesions arising from adjacent structures or from haematogeneous metastasis may also infiltrate this region.     

The potential risk of thrombosis during coronary angiography using nonionic contrast media

The influence of contrast media on coagulation has an important association with thromboembolic complication during coronary angiography. In this study, whole blood was methodically mixed with nonionic contrast medium, Iohexol (IOH), conventional ionic contrast medium, Hypaque-76 (H76), and low osmolar ionic dimer Hexabrix (HB) in vitro. The thrombotic propensity of contrast agents can be evaluated by measuring the clot formation of the mixtures. The experiments were repeated with whole blood after systemic heparinization. In the in vitro study, 5 ml of canine (N = 10) and 3 ml of human (N = 11) whole blood was incubated for 30 min in glass tubes with equal volumes of IOH, H76, HB, and 0.9% NaCl before heparinization. Clot formation with IOH and 0.9% NaCl were seen both in dogs (4.0 +/- 0.7 gm and 5.6 +/- 0.8 gm) and in patients (1.4 +/- 0.9 gm and 2.9 +/- 1.3 gm), whereas no clot was seen with H76 or XB. Following heparinization, no clot was visualized in any mixture of whole blood with contrast media or 0.9% NaCl. Similar results were observed in the catheter-syringe system with canine blood (N = 11) mixed with the contrast agents. Blood clots found in 15 min and 30 min of IOH were 0.07 +/- 0.08 gm and 0.44 +/- 0.20 gm (P less than 0.01) and of NaCl were 0.29 +/- 0.37 gm and 0.69 +/- 0.38 gm (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)     

Interpeduncular fossa sign: CT criterion of subarachnoid hemorrhage

A retrospective study of 100 cerebral computed tomography scans interpreted as displaying subarachnoid hemorrhage was undertaken to determine the frequency of blood in the interpeduncular fossa as a useful radiographic sign. The results indicate that the interpeduncular fossa sign is second only to blood in the Sylvian fissure-circular sulcus area as a reliable indicator of subarachnoid hemorrhage on CT scans.