Fine needle cytology--is aspiration suction necessary? A study of 100 masses in various sites

One hundred consecutive superficial mass lesions in various body sites were sampled by both conventional fine needle aspiration (FNA) and by a fine needle without the application of syringe suction. The latter technique is based on the principle of capillarity and may be termed "fine needle capillary" (FNC) sampling. The two sampling techniques were compared using five objective parameters: (1) the amount of diagnostic cellular material present, (2) the retention of appropriate architecture and cellular arrangement, (3) the degree of cellular degeneration, (4) the cellular trauma and (5) the volume of obscuring background blood and clots. There was no statistically significant difference between the efficacies of the two sampling techniques for any of the parameters studied. FNA sampling was diagnostic in a greater number of cases than was FNC sampling, but this difference was not statistically significant at a level of P = .05. When FNC sampling was diagnostic, it more frequently produced superior-quality material; conventional FNA, although diagnostic in a greater number of cases, mostly produced adequate, rather than superior-quality, material. This trend was not, however, statistically significant at a level of P = .05. These findings differ from those of previous studies (which have shown overall superiority of FNC sampling over conventional FNA sampling) and suggest that the technique of fine needle sampling employed for cytodiagnosis can be left to the personal preference of the operator.     

Mesothelioma in Scotland

In a retrospective study of the incidence of mesothelioma in Scotland for 1950-67 80 cases were traced from pathological reports and biopsy material of malignant tumours invading the pleura and peritoneum. These cases were matched with two sets of controls. Detailed histories of residence, occupation, and degree of exposure to asbestos confirmed that the incidence of mesothelioma in Scotland is similar to that in other parts of Britain.     

Specificity of acyl-homoserine lactone synthases examined by mass spectrometry

Many gram-negative bacteria produce a specific set of N-acyl-L-homoserine-lactone (AHL) signaling molecules for the purpose of quorum sensing, which is a means of regulating coordinated gene expression in a cell-density-dependent manner. AHLs are produced from acylated acyl-carrier protein (acyl-ACP) and S-adenosyl-L-methionine by the AHL synthase enzyme. The appearance of specific AHLs is due in large part to the intrinsic specificity of the enzyme for subsets of acyl-ACP substrates. Structural studies of the Pantoea stewartii enzyme EsaI and AHL-sensitive bioassays revealed that threonine 140 in the acyl chain binding pocket directs the enzyme toward production of 3-oxo-homoserine lactones. Mass spectrometry was used to examine the range of AHL molecular species produced by AHL synthases under a variety of conditions. An AHL selective normal-phase chromatographic purification with addition of a deuterated AHL internal standard was followed by reverse-phase liquid chromatography-tandem mass spectrometry in order to obtain estimates of the relative amounts of different AHLs from biological samples. The AHLs produced by wild-type and engineered EsaI and LasI AHL synthases show that intrinsic specificity and different cellular conditions influence the production of AHLs. The threonine at position 140 in EsaI is important for the preference for 3-oxo-acyl-ACPs, but the role of the equivalent threonine in LasI is less clear. In addition, LasI expressed in Escherichia coli produces a high proportion of unusual AHLs with acyl chains consisting of an odd number of carbons. Furthermore, these studies offer additional methods that will be useful for surveying and quantitating AHLs from different sources.