Relationship between molecular structure, concentration and odor qualities of oxygenated aliphatic molecules.

Increasing the concentration of an odorant increases the number of receptor cells and glomeruli in the olfactory bulb that are stimulated, and it is commonly acknowledged that these represent increased numbers of receptor types. Currently, it is not known whether a receptor type is associated with a unique quality and a unique molecular feature of an odorant, or its activation is used by the brain in a combinatorial manner with other activated receptor types to produce a characteristic quality. The present study investigated the proposal that a molecular feature common to several aliphatic odorants and known to be the key feature required to stimulate the same mitral cells in the olfactory bulb results in a quality that is common to the odorants. Since the common structural feature may activate a specific receptor type possibly at a similar concentration, the qualities of the odorants were determined at seven concentrations where the lowest and highest concentrations were the detection threshold (DT) and 729DT of each subject. A list of 146 descriptors was used by 15 subjects to describe the qualities of each odorant at each concentration. The results indicate that each of the five odorants was characterized by different qualities and the qualities of four of the odorants changed with changes in concentration. Importantly, no quality common to each of the odorants that had the same molecular feature could be identified and it is proposed that identification of the odorants occurs via a combinatorial mechanism involving several types of receptors.

Laparoscopic treatment of liver cysts.

Symptomatic simple liver cysts should be treated. In this report we describe the results of a straightforward, well-tolerated laparoscopic operation for this condition. Between 1990 and 1996 we performed 19 laparoscopic liver cyst excisions. The exposed portion of the cyst wall was excised and a piece of omentum was secured into the remaining cyst cavity to prevent recurrence. The average age of the patients was 65 years (range 30 to 81 years). Eight patients (42%) had single simple cysts, nine patients (47%) had multiple simple cysts, and two patients (11%) had polycystic liver disease. Fifty-three percent of the patients had previous abdominal operations, 47% had undergone previous needle aspirations, and one had previously undergone unsuccessful laparoscopic cyst decompression elsewhere. The indications for surgery included abdominal pain, mass, early satiety, malaise, bloating, and shortness of breath. Two patients underwent concurrent cholecystectomies, and one patient underwent concurrent laparoscopic Nissen fundoplication. Follow-up, which averaged 32 months (range 3 to 68 months), is complete in all patients. There was one treatment failure among the patients with simple cysts. Both patients with polycystic liver disease have had recurrent symptoms. The laparoscopic approach to simple liver cysts is relatively straightforward, and if certain technical principles are adhered to, the success rate is very high.