Satellite radar interferometry for monitoring ice sheet motion: application to an antarctic ice stream.

Satellite radar interferometry (SRI) provides a sensitive means of monitoring the flow velocities and grounding-line positions of ice streams, which are indicators of response of the ice sheets to climatic change or internal instability. The detection limit is about 1.5 millimeters for vertical motions and about 4 millimeters for horizontal motions in the radar beam direction. The grounding line, detected by tidal motions where the ice goes afloat, can be mapped at a resolution of approximately 0.5 kilometer. The SRI velocities and grounding line of the Rutford Ice Stream, Antarctica, agree fairly well with earlier ground-based data. The combined use of SRI and other satellite methods is expected to provide data that will enhance the understanding of ice stream mechanics and help make possible the prediction of ice sheet behavior.

[Navigation techniques in surgery of cranio-cervical junction and upper cervical spine]. / Navigacní techniky v chirurgii kraniocervikálního prechodu a horní krcní pátere.

Spinal navigation has substantially advanced during the past ten years. Surgeons have gained sufficient skills and confidence, and have introduced this technology to the anatomically challenging region of the upper cervical spine and craniocervical junction. The detailed evaluation of individual anatomy, rational pre-operative planning and final intraoperative control improve the safety and precision of classical surgical procedures. As methods technologically evolve, indication criteria change accordingly, but the basic principles of a relevatn choice remain; these are to reduce morbidity due to its three main causes, i.e., mechanical, neurological and vascular. We present an overview of current techniques and discuss their applicability in the region of the upper cervical spine and craniocervical junction. The systems allowing us to obtain live images intra-operatively, such as fluoroscopy or intra.operative CT, seem to be most versatile and accurate, especially when combined with traditional virtual navigation systems. Based on case histories, the authors suggest trends in the development of this field, with a focus on minimally invasive techniques. Key words: navigation, upper cervical spine, craniocervical junction.

Histamine and acute haemorrhagic lesions in rat gastric mucosa: prevention of stress ulcer formation by (+)-catechin, an inhibitor of specific histidine decarboxylase in vitro.

Acute haemorrhagic lesions in the oesophagus, stomach and duodenum ('stress ulcers') occur relatively often under clinical conditions and are always dangerous to the patient (lethality rate about 70%). Since conservative and surgical treatment are without significant success up to now, prevention by adaptation to stressors or by administration of drugs seems mandatory. An improved technique for producing acute gastric lesions in rats by immobilization and a new method for assessing this disease in the animals is presented in this communication. High precision is obtained within a single experimental series especially from day to day. Since histamine was suggested to be involved in the pathogenesis of stress ulcer disease, (+)-catechin, a rather specific inhibitor of specific histidine decarboxylase from rat stomach, was tested in immobilized rats. It prevented the formation of acute gastric lesions by 80% in seven series of experiments lasting for half a year. Since the drug has low toxicity in man, it is recommended for clinical trials.