Quantitation of hindered amine light stabilizers in plastic materials by high performance liquid chromatography and mass spectrometric detection using electrospray ionization and atmospheric pressure photoionization.

In this work new high performance liquid chromatographic methods in combination with mass spectrometry have been developed for the quantitation of hindered amine light stabilizers (HALS) which are commonly used as monomeric and oligomeric species for stabilization of plastic materials. These analytes are difficult to separate under traditional reversed phase conditions. In the present study new silica-based pH stable reversed phases that had become available recently were investigated for HALS analysis, and turned out to be well suited employing mobile phases at a pH of around 11 adjusted by addition of ammonia. Detection was done by mass spectrometry employing both time-of-flight and triple quadrupole mass analyzers. The performance of electrospray ionization (ESI) as well as atmospheric pressure photoionization (APPI) was investigated and compared. Despite the high pH of the mobile phase, an excellent ionization could be obtained in the positive ion mode. ESI provided slightly lower limits of quantitation (on average a factor of 2) in comparison with APPI. The method allowed the quantitation of a range of different HALS down to 0.05-0.005% (depending on the HALS) in polymeric materials. Sample preparation consisted in dissolving the sample in toluene and precipitation of the polymer with acetone. The procedure can be routinely applied to aging tests of plastic materials in order to predict the lifetime of plastic components.

Blood transfusion and the risk of recurrence in squamous carcinoma of the vulva.

OBJECTIVE: Our purpose was to determine if postoperative transfusion increases the risk of recurrence in patients who have undergone operation for squamous carcinoma of the vulva. STUDY DESIGN: Data from 154 patients with squamous carcinoma of the vulva treated at Indiana University Medical Center from 1974 through 1988 were retrospectively analyzed to determine the influence of postoperative transfusion on recurrence risk. Patients were evaluated for International Federation of Gynecology and Obstetrics stage, lesion size, lesion depth, grade, patient age, number of transfusions, and recurrence with chi 2 analysis, Fisher's exact test, and the Student t test where appropriate. RESULTS: Transfusions were given to 57 patients (37%) with a mean of 2.2 units delivered (range 1 to 5 units). Transfused patients differed significantly from those not transfused in that they had more advanced stage (p = 0.002), more positive nodes (p = 0.03), and higher grade lesions (p = 0.03), and they were older (p = 0.005). Recurrences developed in 25 patients (16.2%). Recurrences were more common in those with positive nodes (10-39, 25.6%) than in those with negative nodes (8/99, 8%), (p = 0.01). Only nodal status was predictive of recurrence in this series. Transfused patients had a 14% (8/57) rate of recurrence, whereas the recurrence risk was 17.5% (17/97) in those not transfused (p = 0.65). CONCLUSIONS: We have been unable to confirm that postoperative transfusions increase the risk of recurrence in patients with squamous carcinoma of the vulva.

On the structure of albumin-bound bilirubin. Selective binding of intramolecularly hydrogen-bonded conformational enantiomers.

The intramolecularly hydrogen-bonded bichromophoric tetrapyrrole pigments, bilirubin-IX alpha and mesobilirubin-XIII alpha, adopt either of two folded, intramolecularly hydrogen-bonded, enantiomeric conformations which are in dynamic equilibrium in solution. Added human serum albumin binds preferentially, although not necessarily exclusively, to one conformational enantiomer, and the solutions exhibit bisignate circular dichroism Cotton effects in the region of the pigment's long wavelength electronic transition. In contrast, the bichromophoric tetrapyrrole pigment mesobilirubin-IV alpha, which is incapable of adopting intramolecularly hydrogen-bonded folded conformations, and the monochromophoric pyrromethenone, xanthobilirubic acid, show only monosignate induced circular dichroism Cotton effects under the same conditions. Application of exciton coupling theory indicates a preference for complexation of the right-handed (or positive) chirality conformational enantiomer of bilirubin-IX alpha or mesobilirubin-XIII alpha to human serum albumin at physiologic pH.

Buprenorphine as new treatment for heroin dependence.

Dr. Jasinski suggested years ago that on the basis of some preliminary findings buprenorphine could hold promise for the treatment of heroin dependence (D. Jasinski, J.S. Pevnick and J.D. Griffith, Arch. Gen. Psychiatry, 35 (1978) 501)). No significant report has been published to confirm that assumption, and no treatment program seems to have started on that ground. Buprenorphine is now available in several countries including Belgium. We tried to devise a treatment program for heroin addicts combining chemotherapy with sublingual buprenorphine and psychotherapy. The interim results of this treatment program--initiated in 65 heroin addicts and undertaken by 34 of them for periods varying from 2 to 17 months--seem sufficiently promising to pursue our research.