On the origin and evolution of the Roeder knot and loop--a geometrical review

The first laparoscopic sliding knot to be described was the Roeder knot; it has been used for a variety of procedures in all surgical disciplines. It was surmised that the introduction of new modifications in the geometry of the knot paralleled the introduction of its new indications, and that not all modifications improved its security. Therefore, a geometrical review was made of all modifications and all data on knot security and loop security of the knot were analyzed. The introduction of the original knot and its 14 applicable modifications paralleled the increase in minimally invasive techniques and the spread of these techniques in all the medical specialties. Roeder loop security depends predominantly on the number of initial turns around the standing part. Its knot security depends on the additional half hitches used to backup the knot after it has been tightened. Only a few of the modifications improved the security of the knot or its previous modifications.     

Olfaction: a potential cognitive marker of psychiatric disorders

Cognitive deficits are well documented in psychiatric disorders, particularly in schizophrenia and depression. Cognitive activity roots in perceptions. However, research on sensorial alterations in psychiatric conditions has mainly focused on visual or auditory processes and less on olfaction. Here, we examine data on olfactory deficits in psychiatric patients using a systematic review of recent publications. Schizophrenic patients are mainly characterized by no reliable change in odour sensitivity and by a deficit in odour identification, recognition and discrimination. Depressed patients principally exhibit a deficit in the hedonic aspects of this perception, even if, in some case, alterations in sensitivity or identification are also found. Changes in odour perception are also found in dementia and in some neurodegenerative disease, but in this case alterations concern all aspects of the sensorial experience (detection threshold, identification and recognition). Taken together, these data indicate that olfactory abnormalities might be a marker of psychiatric conditions, with a specific pattern for each disease.