Preparation of monoclonal antibodies against okadaic acid prepared from the sponge Halichondria okadai

T. Usagawa, M. Nishimura, Y. Itoh, T. Uda and T. Yasumoto. Preparation of monoclonal antibodies against okadaic acid prepared from the sponge Halichondria okadai. Toxicon27, 1323–1330, 1989.—Three murine monoclonal antibodies, OA-1, OA-2 and OA-3, against okadaic acid were prepared from hybridoma clones obtained by fusion of mouse 653 myeloma cells with mouse immune spleen cells sensitized to okadaic acid-ovalbumin conjugate. Each antibody reacted with dinophysistoxin-1 ( = 35-methylokadaic acid) as well as okadaic acid, but did not react with the other diarrhetic shellfish poisons or related compounds, such as 7-O-palmitoyl-okadaic acid (analogue of dinophysistoxin-3), pectenotoxin-1 and yessotoxin. A competitive inhibition enzyme-linked immunosorbent assay which employed OA-3 antibody was performed and showed a sensitivity of about 10ppb (10ng/ml) for okadaic acid. This simple and time-saving ELISA assay system may be useful for the specific detection of diarrhetic shellfish poisons.     

Evaluation of intraoperative transesophageal two-dimensional echocardiography

Transesophageal two-dimensional echocardiography (TEE) was evaluated in 11 patients who underwent myocardial revascularization. The TEE transducer was positioned to view the left ventricular (LV) short-axis at the level of the papillary muscles (midcavity). Good quality echocardiographic images were obtainable in ten of 11 patients. Global LV function was assessed by measuring LV end-diastolic and end-systolic area and computing the fractional area change (FAC). Measurements of LV areas and FAC had excellent intraobserver reproducibility. Regional LV function was analyzed in two ways after dividing the short-axis view of the LV into four or five anatomic segments. Systolic wall thickening (SWT) of the myocardium was measured in each of four segments by digitization of the endocardial and epicardial borders of the LV and determining the fractional wall thickening. Measurements of SWT were not reproducible, primarily because of a difficulty in delineating the epicardial border of the LV accurately. In the second method, regional wall motion (RWM) in each of five segments was graded according to a previously developed scoring system. RWM analysis proved to be a measurement with excellent interobserver and intraobserver reproducibility. TEE was performed without complication and found to be a reproducible method for assessing global and regional LV function. Quantitative analysis is tedious and, therefore, currently not available on-line in the operating room.     

Absence of correlation between cytotoxicity and drug transport by P-glycoprotein in clinical leukemic cells.

Development of resistance to cytotoxic agents is a common problem in the treatment of acute leukemia. In cell lines having multidrug resistance (MDR) phenotype, a decrease in the intracellular accumulation of drugs has been closely related to the overexpression of P-glycoprotein/mdr1 genes. We analyzed the relationship between the cytotoxicity of adriamycin (ADR) in vitro, intracellular accumulation of ADR, and the expression of P-glycoprotein on fresh leukemic cells from 19 patients at their initial presentation and from 9 relapsed patients. Pretreatment patients showed significantly higher ratio of complete remission than relapsed patients, and mean value of IC50 for adriamycin in initial presentation was higher than at relapse. But we found no significant relationship between in vitro cytotoxicity and drug transport. In addition, only 2 of the 5 relapsed patients examined by monoclonal antibody C219 expressed the P-glycoprotein. These results suggest that the acquisition of clinical drug resistance may involve various mechanisms other than the reduction of drug accumulation with P-glycoprotein expression.     

Tumor response to thermoradiation therapy: use of CT in evaluation

Seventy-two tumors, mostly in deep locations, were studied retrospectively with computed tomography (CT) before and after thermoradiation therapy. Hyperthermia was administered locally or regionally with radio frequency capacitive heating equipment after irradiation (total dose, 20-70.2 Gy) for 40-60 minutes per session in a total of four to 13 sessions. Sixteen of the 72 tumors showed complete regression. Tumor regression was not related to the average maximum or minimum tumor temperature. CT scans obtained after thermoradiation therapy demonstrated a clear low-density area in 32 of 56 tumors that did not regress completely. Histopathologic examinations, performed in 14 of the 32 tumors, showed the low-density area to be massive coagulation necrosis. The low-density area was classified into three types according to its percentage area in the tumor: type 3 (more than 80%), type 2 (50%-80%), and type 1 (less than 50%). The type correlated with the average maximum and minimum tumor temperature, and follow-up observations and histopathologic examinations showed great effects in most of the type 3 tumors.