Evaluation ofin vitro drug screening leads using experimental models of human ovarian cancer

Summary Five compounds which were identified as potential new anticancer drugs inin vitro screening with the human tumor colony forming assay were selected for further evaluation usingin vitro andin vivo models of human ovarian cancer. Three of five compounds were found to inhibitin vitro colony formation of ovarian cancer cell lines derived from both untreated and combination chemotherapy refractory patients. One compound was also found to prolong survival in a human ovarian carcinoma xenograft model system. This compound, chloroquinoxaline sulfonamide, was selected for development and has shown preliminary indication of activity in phase I clinical testing.     

Early diagnosis of SARS: lessons from the Toronto SARS outbreak

The clinical presentation of SARS is nonspecific and diagnostic tests do not provide accurate results early in the disease course. Initial diagnosis remains reliant on clinical assessment. To identify features of the clinical assessment that are useful in SARS diagnosis, the exposure status and the prevalence and timing of symptoms, signs, laboratory and radiographic findings were determined for all adult patients admitted with suspected SARS during the Toronto SARS outbreak. Findings were compared between patients with laboratory-confirmed SARS and those in whom SARS was excluded by laboratory or public health investigation. Of 364 cases, 273 (75%) had confirmed SARS, 30 (8%) were excluded, and 61 (17%) remained indeterminate. Among confirmed cases, exposure occurred in the healthcare environment (80%) or in the households of affected patients (17%); community or travel-related cases were rare (<3%). Fever occurred in 97% of patients by the time of admission. Respiratory findings including cough, dyspnea and pulmonary infiltrates evolved later and were present in only 59, 37 and 68% of patients, respectively, at admission. Direct exposure, fever on the first day of illness, and elevated temperature, pulmonary infiltrates, lymphopenia and thrombocytopenia at admission were associated with confirmed cases. Rhinorrhea, sore throat, and an elevated neutrophil count at admission were associated with excluded cases. In the absence of fever or significant exposure, SARS is unlikely. Other clinical, laboratory and radiographic findings further raise or lower the likelihood of SARS and provide a rational basis for estimating the likelihood of SARS and directing initial management.     

Influence of zinc on Pseudomonas aeruginosa susceptibilities to imipenem.

Serial dilution susceptibility testing of imipenem against 59 clinical isolates of Pseudomonas aeruginosa, conducted simultaneously on single lots of Difco and BBL Mueller-Hinton agar (MHA), resulted in MICs for 90% of strains tested of 8 and 16 micrograms/ml, respectively. MICs for Escherichia coli, Klebsiella pneumoniae, and Pseudomonas spp. were also higher on BBL MHA. Quantification of the cation content of the two MHAs by atomic absorption spectroscopy demonstrated that the zinc concentration in BBL MHA was 15 times greater than that measured in Difco MHA (2.61 and 0.17 micrograms/ml, respectively). Concentrations of calcium, magnesium, iron, manganese, and copper in the two agars were similar. Addition of zinc to Difco MHA resulted in increases in MICs of imipenem for P. aeruginosa but not in the MICs of ceftazidime or cefpirome for P. aeruginosa (P < 0.01). A lesser zinc effect was seen on the activity of imipenem against E. coli, K. pneumoniae, and Pseudomonas spp. The activities of ceftazidime and cefpirome were similar on both MHAs when tested against all gram-negative organisms in this study. Thus, the effect of zinc in MHA was clearly demonstrated by a significant increase in the MICs of imipenem for P. aeruginosa, and, to a lesser extent, for other gram-negative bacilli.     

Anaerobes survive in clinical specimens despite delayed processing.

Quantitative cultures were performed on 11 purulent specimens of at least 2 ml from mixed aerobic-anaerobic infections to determine the effect of prolonged exposure to air on the recovery of anaerobes. The specimens were processed immediately and after air exposure for periods of 10 min and 1, 4, and 24 h. There were at total of 37 anaerobic and 36 aerobic strains recovered from these specimens. Of the anaerobes, 26 were isolated with the initial processing and 22 were still present after air exposure for 24 h. The numerical concentrations of anaerobes showed little change with the sequential samplings. Eleven anaerobic strains were not detected in the initial culture but appeared sporadically in subsequent cultures. Using the types of specimens and method of processing employed in this study, most pathogenic anaerobes survived in purulent exudate despite extended periods of air exposure. The major cause of discrepent results with periodic cultures was attributed to vagaries in sampling.     

Specificity of the complement resistance and cell association phenotypes encoded by the outer membrane protein genes rck from Salmonella typhimurium and ail from Yersinia enterocolitica.

Virulence-associated phenotypes of an outer membrane protein gene family of members of the family Enterobacteriaceae were compared by means of pBR322 constructs transformed into Escherichia coli HB101.rck (Salmonella typhimurium) and ail (Yersinia enterocolitica) promote serum resistance and eukaryotic cell invasion, properties not shared by other members of the gene family, pagC, ompX, and lom.     

Genomic deletions and precise removal of transposable elements mediated by short identical DNA segments in primates

Insertion of transposable elements is a major cause of genomic expansion in eukaryotes. Less is understood, however, about mechanisms underlying contraction of genomes. In this study, we show that retroelements can, in rare cases, be precisely deleted from primate genomes, most likely via recombination between 10- to 20-bp target site duplications (TSDs) flanking the retroelement. The deleted loci are indistinguishable from pre-integration sites, effectively reversing the insertion. Through human-chimpanzee-Rhesus monkey genomic comparisons, we estimate that 0.5%-1% of apparent retroelement "insertions" distinguishing humans and chimpanzees actually represent deletions. Furthermore, we demonstrate that 19% of genomic deletions of 200-500 bp that have occurred since the human-chimpanzee divergence are associated with flanking identical repeats of at least 10 bp. A large number of deletions internal to Alu elements were also found flanked by homologies. These results suggest that illegitimate recombination between short direct repeats has played a significant role in human genome evolution. Moreover, this study lends perspective to the view that insertions of retroelements represent unidirectional genetic events.     

Quantitative effects of osmotic diuresis following angiographic contrast administration

Osmotic diuresis resulting from the administration of angiographic contrast poses the potential threat of marked volume losses obligated by the renal excretion of non-reabsorbable solute. We prospectively assessed urinary excretion of solute and water following cardiac angiography in 14 euvolemic subjects without preexisting renal disease, by a protocol that allowed each patient to serve as his own control. During the initial 6 h after the beginning of angiography, contrast administration resulted in increased total osmolar excretion from a control rate of 0.79 +/- 0.09 to 1.09 +/- 0.09 mOsm/min (P less than .05) with a return to control values thereafter. Surprisingly, sodium, potassium, and chloride excretion rates did not differ significantly from control values. After subtraction of the molar contribution of electrolytes, urea, and creatinine from the total osmolar excretion rate, it was apparent that the "residual osmolar excretion rate" of 0.48 +/- 0.05 mOsm/min was markedly elevated over the control value of 0.11 +/- 0.05 mOsm/min (P less than .01), reflecting the excretion of contrast agent. Despite the marked osmotic diuresis, urine output during this period (3.9 +/- 0.2 cc/min) did not differ significantly from the control value of 4.0 +/- 0.3 cc/min. We conclude that marked volume losses are not a necessary concomitant of contrast-induced osmotic diuresis in the euvolemic cardiac patient without renal disease.     

Surgical resection following interleukin 2 therapy for metastatic renal cell carcinoma prolongs remission.

Records of 399 patients with metastatic renal cell carcinoma treated with interleukin 2 with or without lymphokine-activated killer cell immunotherapy enrolled in 14 separate clinical trials from multiple institutions were reviewed to determine whether patients with a partial response to interleukin 2 therapy would benefit from surgical resection of residual tumor. Sixty-two patients demonstrated objective responses (15.5%), 18 (4.5%) complete and 44 (11.0%) partial. Eleven patients underwent resection of residual tumor in the lung, kidney, retroperitoneum, or pelvis so that they had "surgically no evidence of disease" (SNED). Of these, 10 had partial responses, and one patient with progressive disease had a complete response. Comparison of response duration showed no difference between the complete response and SNED groups, but there was a significant difference between each of these groups and the partial response group. At this writing, all 11 patients in the SNED group remained alive without evidence of disease (median follow-up, 21 months). In contrast, only 14 patients (76%) with complete responses and 15 patients (35%) with partial responses remained free of disease progression. Enhanced survival of the complete response and SNED groups compared with the partial response group borders on significance and awaits longer follow-up. These data suggest that surgical resection, if technically feasible, may benefit patients who show a partial response to interleukin 2 treatment for metastatic renal cell carcinoma.