Structure-activity studies of antitumor agents based on pyrrolo[1,2-a]benzimidazoles: new reductive alkylating DNA cleaving agents

Described herein are structure-activity studies of new antitumor agents based on the pyrrolo[1,2-a]benzimidazole (PBI) ring system. These compounds were designed as new DNA cross-linkers mimicking the mitomycin antitumor agents. Actually, the PBI derivatives were found to have anthracycline-like features: (i) shared cross resistance with doxorubicin in a human myeloma line, (ii) cardiotoxicity, and (iii) excellent DNA strand cleaving capability. The DNA strand cleavage is thought to result from reductive alkylation of DNA followed by the generation of reactive oxygen radicals. The best antitumor agent studied is 6-N-aziridinyl-3-hydroxy-7-methyl-2,3-dihydro-1H-pyrrolo- [1,2-a]benzimidazole-5,8-dione 3-acetate (PBI-A), which possesses nanomolar IC50 values against various human ovarian and colon cancer cell lines.     

Genetic linkage analysis of nerve growth factor (beta) in familial Alzheimer's disease.

Recent studies have not shown linkage of late-onset (mean age, greater than 60 years) familial Alzheimer's disease (FAD) to the chromosome 21 locus reported linked to early-onset FAD. Beta nerve growth factor (beta-NGF) has been considered a candidate gene in the pathogenesis and therapy of FAD, based on its localization in the cortex and hippocampus and its ability to enhance the growth and survival of cholinergic neurons. A 1.5-kb fragment of the beta-NGF gene was used to detect a BglII restriction fragment length polymorphism, which was then used for linkage analysis. A total of 30 families (27 late onset) with 147 affected members were studied. Close linkage (theta less than or equal to 0.03, z less than or equal to -2.00) of late-onset FAD with beta-NGF was excluded. Two apparent obligate crossovers between affected members were detected in different autopsy-confirmed families. Based on these results, beta-NGF is not the gene responsible for late-onset FAD in the families analyzed.     

Second-look laparotomy in epithelial ovarian carcinoma. Prognostic factors associated with survival duration

This article that reports on 70 consecutive patients is one of only a few studies of advanced ovarian cancer that have attempted to define predictive factors associated with survival duration after second-look laparotomy. As in many other investigations, several factors have been analyzed for predicting second-look outcome. The prognostic variables analyzed in this study included age, stage, histologic grade, residual disease status after initial surgery, and type (cisplatin versus no cisplatin) and number of cycles of chemotherapy. Only stage (P = 0.002) and optimal disease (less than 2 cm residual tumor size) after initial surgery (P less than 0.001) were significantly associated with the absence of disease at second-look laparotomy, and both were significant predictors of second-look outcome in a multivariate logistic regression model. Their impact on actuarial survival after second-look laparotomy diminished, however. Actuarial survival after second-look laparotomy was associated with residual tumor size at second-look surgery (P = 0.02). According to second-look findings, the 3-year actuarial survival rates and standard errors were as follows: no pathologic evidence of disease, 80.7% +/- 13.4% 3-year survival; microscopic disease plus less than or equal to 2 cm residual disease, 49.1% +/- 13.1% survival; and gross residual disease (i.e., greater than 2 cm maximum tumor diameter), 29.5% +/- 11.4% survival. We also examined the effect of extensive tumor resection at second-look laparotomy on survival for patients with greater than 2 cm gross residual disease. Optimum resection (less than 2 cm residual tumor mass) resulted in significantly greater survival than suboptimum resection (P less than 0.001). This strongly suggests that there is a survival advantage associated with optimum resection at second-look laparotomy.     

A water deprivation test for the differentiation of polyuric disorders in birds

A water deprivation test was developed for the differentiation of polyuric disorders in birds using the racing pigeon as a model. For a period of 3 days of food and water deprivation, urine and plasma osmolalities and body weight of 40 clinically healthy racing pigeons were monitored. Reference values for urine osmolality after 40 hours of food deprivation were 79 to 480 mOsmol/kg. After 64 hours of food deprivation and 24 hours of water deprivation these values were 450 to 875 mOsmol/kg. No significant rise in urine osmolality was seen after the first 24 hours of water deprivation. It is concluded that an urine osmolality greater than 450 mOsmol/kg is indicative of a normal concentrating capacity of the kidney in the pigeon. Data from the literature suggest that these values can be applied to other avian species.     

N-acetylcysteine and liberase improve success of hepatocyte isolation and viability of hepatocytes isolated from normal and diseased liver

BackgroundSuccessful hepatocyte isolation is crucial for development of cellular transplantation and biochemical research. Most researchers isolate hepatocytes from surplus donor tissue or normal tissue removed during resection of liver tumours. However, most tissue available for research is from explanted diseased liver and donor tissue rejected for transplant. We previously described our experience of hepatocyte isolation using liberase from such livers with a success rate of 51% and median viability of 40%. Liberase is a highly purified collagenase that has been shown to improve the viability of isolated porcine hepatocytes. N-acetylcysteine (NAC) has been shown to improve the viability of human hepatocytes isolated from steatotic donor tissue. The aim of this study was to determine the effect of both reagents in combination on the outcome of hepatocyte isolation from normal and diseased liver.MethodsHepatocytes were isolated from 30 consecutive liver specimens as previously described (old protocol). A further 30 consecutive liver specimens were perfused with buffer containing NAC and standard collagenase substituted by liberase (new protocol). Success was defined as maintenance of cell adhesion and morphology for 48 h and/or their successful use in laboratory studies. Mann-Whitney tests were used to compare results. Fisher's exact test was used for categorical data.FindingsBaseline factors were similar for both groups. The delay to tissue processing was slightly less in the new protocol group (median 2 h vs 4 h, p=0·007). The success rate improved from 40% (12/30) with the old protocol to 70% (21/30) with the new protocol (p=0·037), and the median viable cell yield increased from 7·3 × 10⁴ to 28·3 × 10⁴ cells per g tissue (p=0·003). After multivariable analysis adjusting for the difference in time delay, the success rate (p=0·014) and viable cell yield per g tissue (p=0·001) remained significantly improved.InterpretationNAC and liberase greatly improve the success of hepatocyte isolation and result in a significantly higher viable cell yield. Use of these agents may improve the availability of hepatocytes for transplantation as well as laboratory research.FundingUK Medical Research Council.