The purpose of the work presented here was to evaluate the influence of solution composition and analyte characteristics on responsiveness to analysis with negative ion electrospray ionization mass spectrometry. The responses of a series of structurally diverse acidic molecules were compared in various solvents. Response was generally observed to be higher in methanol than acetonitrile and response for all analytes was poorer when water was mixed with the organic solvent. A positive correlation between negative ion ESI-MS response and log P was observed when either acetonitrile or methanol was used as the electrospray solvent. This result was expected because analytes with significant nonpolar character should be particularly responsive to ESI-MS analysis due to their higher affinity for electrospray droplet surfaces. It was also predicted that highly acidic analytes would be most responsive to analysis with negative ion ESI-MS due to their tendency to form negative ions. However, for the analytes studied here, acidity was found not to have a consistent influence on ESI-MS response. Many of the highly acidic molecules were quite polar and, consequently, were poorly responsive. Furthermore, the deprotonated molecular ion was detected for a number of molecules with very high pKa values, which would not be expected to form negative ions in the bulk solution. Ultimately, these results indicate that acidity is not a conclusive parameter for prediction of the relative magnitudes of negative ion ESI-MS response among a diverse series of analytes. Analyte polarity does; however, appear to be useful for this purpose. (J Am Soc Mass Spectrom 2005, 16, 446 -455)

Electrospray ionization mass spectrometry is a critically important technique for the determination of small molecules, but its application for this purpose is complicated by its selectivity. For positive ion ESI-MS analysis of basic analytes, several investigators have pointed to the importance of analyte basicity as a source of selectivity. Currently, however, it is not known whether basicity in the gas phase or in solution is ultimately most important in determining responsiveness. The objective of these studies was to investigate the relative importance of basicity in solution and in the gas phase as factors that predict selectivity in positive ion ESI-MS analysis. ESI-MS response was compared for a diverse series of protonatable analytes in two different solvents, neat methanol and methanol with 0.5% acetic acid. A correlation was observed between analyte pK b and electrospray response. However, the response for the analytes with very high pK b values was significantly higher than would be expected based on concentration of the protonated form or the analyte in solution, and this higher response did not appear to result from gas-phase proton transfer reactions. Although all of the analytes investigated had higher gas-phase basicities than the solvent, their relative responses were not dictated by gas-phase basicity. Higher response was observed for all of the analytes studied in acidified methanol compared with neat methanol, and this higher response was most pronounced for weakly basic analytes. These findings support the use of analyte pK b for rational method development in ESI-MS analysis of small molecules.

Epidemiologic data on local complications after breast augmentation are scarce. In particular, few prospectively collected data are available on modern breast implants on this issue. Using data from the Danish Registry for Plastic Surgery of the Breast, the authors examined determinants of surgery-requiring complications and capsular contracture grades III to IV among 2277 women who underwent cosmetic breast implantation from June 1999 through April 2003. During an average follow-up period of 1.6 years after implantation, 4.3% of these women (3% of implants) required secondary surgery as a result of short-term complications. The most frequent clinical indications for surgery were displacement of the implant (38%), capsular contracture grades III to IV (16%), ptosis (13%), and hematoma (11%). Overall, the authors found that inframammary incision and subglandular placement were associated with decreased risks of developing complications requiring surgical intervention, whereas implants larger than 350 mL increased the risk of such complications (relative risk [RR], 2.3; 95% confidence interval [CI], 1.3-4.0). Thirty-nine Baker III to IV capsular contractures were identified, of which 22 were treated surgically within the study period. Submuscular placement of the implant decreased the risk of capsular contracture grades III to IV (RR, 0.3; 95% CI, 0.2-0.8), whereas surgical routes other than inframammary and drainage of implant cavity were associated with increased risk of capsular contracture. Current surgical practices and modern implants used for breast augmentation produce fewer short-term complications than procedures and devices of the past. This prospective study indicates that surgical procedures are more important predictors for local (short-term) complications than implant or patient characteristics.

Concern has been raised recently regarding the absence of information on the occurrence and severity of local complications after cosmetic breast implantation. The authors evaluated the occurrence of local complications in a large epidemiological retrospective cohort study of women with cosmetic breast implants in Denmark. All women with breast implants were identified from the files of two private clinics of plastic surgery in Denmark. Information on implant characteristics, surgical procedure, as well as short- and long-term complications was obtained through medical record review. Patient characteristics were obtained through a self-administered questionnaire. A total of 754 women (1,572 implants) had at least one cosmetic implantation performed at the study clinics. Average age at implantation was 32 years. Implant types included silicone double lumen with textured surface, 31.2%; silicone single lumen with textured surface, 27.8%; silicone single lumen with smooth surface, 24.5%; silicone double lumen with smooth surface, 0.8%; and other or missing information, 15.7%. Average implant size was 247 ml (range, 110-630 ml). Placement was submuscular for 91.3% of implants, subglandular for 2.6%, and 6.1% had no available information. Overall, 77.8% of implantations were not followed by complications, 17.8% were followed by one complication, 3.6% were followed by two complications, and 0.8% were followed by three or more complications. In 94.6% of implantations, no additional hospitalizations were recorded as a result of complications. Forty-seven of 57 explantations/reimplantations were secondary to postoperative complications. General complications such as hematoma and infection were rare, occurring in 2.3% and 2.0% of implantations respectively. Capsular contracture remains the most common complication, occurring in 11.4% of implantations. In this investigation, among the first epidemiological studies of local complications, the authors found cosmetic breast implant surgery to be associated with a low frequency of normal surgical complications such as infection, hematoma, and wound dehiscence. Most complications were mild and did not lead to additional hospitalization. The complication that led most frequently to the need for additional surgery/hospitalization was capsular contracture. Kjøller K, Hölmich LR, Jacobsen PH, Friis S, Fryzek J, McLaughlin JK, Lipworth L, Henriksen TF, Jørgensen S, Bittmann S, Olsen JH. Epidemiological investigation of local complications after cosmetic breast implant surgery in Denmark.