Activity of different Candida antarctica lipase B formulations in organic solvents.

The activity of different formulations of Candida antarctica lipase B (CALB), such as crude CALB, purified CALB, purified CALB lyophilized with PEG (CALB + PEG) or oleic acid (CALB + OA), and the commercial formulation Novozym 435, was determined in toluene, carbon tetrachloride, and 1,4-dioxane at various water activities (a(w)). The reaction between vinylacetate and 1-octanol was used as the model reaction and both transesterification (formation of 1-octylacetate) and hydrolytic (formation of acetic acid from vinylacetate) activities were determined. For equal amounts of lipase protein, CALB + PEG (and to a lesser extent CALB + OA) displayed higher activity than that of the other formulations; for instance, in toluene (a(w) < 0.1), it was 260-, 13-, and 1.8-fold more active than crude CALB, purified CALB, and Novozym 435, respectively. Moreover, the transesterification activity of CALB + PEG was of the same order of magnitude (51%) of the activity shown by the enzyme in the hydrolysis of vinylacetate in aqueous buffer. These results suggest that PEG and oleic acid could act as lyoprotectants, preventing the formation of intermolecular interactions during the lyophilization process that might be responsible for protein denaturation. No diffusional limitation was observed for CALB + PEG-catalyzed reactions. Purified CALB, in contrast to the other formulations, showed a marked activity increase (2.1 to 7.8-fold) as a function of a(w) and, in 1,4-dioxane, it was 3.5-fold more active when it was added to the solvent after previous dissolution of the lyophilized powder in water.

Conservative management of T1-T2N0 supraglottic cancer: a retrospective study.

PURPOSE: Evaluate the results of conservative management of early-stage supraglottic cancer. PATIENTS AND METHODS: A retrospective analysis of 166 consecutive T1-T2N0 cases of squamous cell carcinoma of the supraglottic larynx, treated conservatively between 1983 and 1992, was performed. Sixty-six patients received conservative surgery (CS), whereas 100 patients received definitive radiation therapy (RT). Surgical procedures included horizontal supraglottic laryngectomy in 38 patients, extended supraglottic laryngectomy in 16 patients, and reconstructive laryngectomy with cricohyoidopexy in 12 patients. Elective bilateral neck dissection was always performed. Radiotherapy was delivered with 60Co or 6 MV photons to the primary laryngeal tumor and the upper and mid neck nodes (level II and III), whereas supraclavicular nodes (level IV) were electively irradiated only in 54 patients with T2N0 tumors. Fifty-two patients received conventional fractionation, whereas 31 patients were irradiated according to a twice-a-day fractionation regimen. The median total tumor dose was 67 Gy (range, 64 to 72 Gy). RESULTS: The 5-year overall survival of the whole series was 72.7% +/- 4.5. In patients treated with CS, the 5-year disease-free survival was 88.4% +/- 4.5 versus 76.4% +/- 6.1 for patients who received RT. Salvage surgery was effective in rescuing 2 of 3 CS failures and 12 of 25 RT failures. The overall incidence of secondary tumors (11%) and distant metastases (5%) was relatively low, although together they account for 15% of all deaths. Complications of CS were significantly correlated to the extent of surgical procedure. A multivariate analysis performed in the RT group showed that performance status, tumor grade, and fractionation regimen significantly influenced disease-free survival. CONCLUSION: Conservative management of T1-T2N0 supraglottic cancer, either by CS or RT, can achieve good cure rates with larynx preservation for the majority of the patients (82% overall; 95% in the CS group and 72% in the RT group). The decision between different conservative treatment modalities may be influenced by the patient's conditions, tumor characteristics, treatment modalities, and also economic costs.

Role of postoperative radiation therapy in the management of early stage primary gastric non-Hodgkin's lymphomas: a retrospective analysis.

BACKGROUND: Clinical approaches to early primary gastric non-Hodgkin's lymphomas have not yet been clearly defined, and the role of postoperative radiotherapy remains a matter of discussion. METHODS: Twenty-seven patients with early primary gastric non-Hodgkin's lymphoma were observed from December 1978 to December 1990 at our Institution. They were staged according to Musshoff and Schmidt-Volmer (19) as I E (n = 16), II E 1 (n = 7) and II E 2 (n = 4). All of them underwent local combined treatment, consisting of surgery and postoperative radiotherapy; chemotherapy was also administered to 10 patients, mainly with the CHOP regimen, for 4-6 cycles before radiotherapy. Irradiation was delivered using 10 MV photons from a linear accelerator. Large abdominal fields were employed in 21 cases with daily fractions of 1.5-2 Gy up to a median total dose of 30 Gy (range: 27-36 Gy). Six patients were irradiated only on the surgical bed up to 40.5 Gy (range: 39-40.5 Gy). RESULTS: The 5-year overall and disease-free survivals were respectively 92.4% and 89.8%. The main known prognostic indicators, stage of disease, type of surgery as well as age and sex, were not found to be statistically significant in our series. No clear difference emerged between patients sequentially treated with the combination surgery-chemotherapy-radiotherapy and those who did not receive adjuvant chemotherapy. Two patients recurred at distant sites, but no local failure was seen during the follow-up. CONCLUSIONS: Although no firm conclusion can be drawn, our experience, in agreement with recent published reports, points out that the use of postoperative radiotherapy is associated not only to favorable results in terms of local control and survival, but also, and moreover, to a negligible incidence of side effects and sequelae. However, in the absence of multi-institutional prospective randomized studies, whose activation is nowadays strongly warranted, the exact role of adjuvant therapies remains a matter of discussion, and the optimal treatment of early primary gastric non-Hodgkin's lymphoma still depends on individual experience and the physician's philosophy.