Preclinical evaluation of illudins as anticancer agents

Illudins are low molecular weight natural products which were previously evaluated as anticancer drugs using rodent tumor models. In the present studies, we used in vitro cultures of human cancer cells to reevaluate their potential as anticancer agents. Using continuous exposure, Illudins S and M were cytotoxic to human leukemia cells at concentrations of 6-100 nM, but dihydroilludin M was 3 orders of magnitude less toxic, thus identifying a ketone site as a structural feature critical for cytotoxicity. Cytokinetic studies showed that illudin S caused a complete block at the G1-S phase interface of the cell cycle. Kinetics of inhibition of radiolabeled thymidine, uridine, and leucine incorporation suggested a primary effect on DNA synthesis. In colony and liquid culture assays, cell killing was time dependent but near maximal with a 2-h exposure. Myeloid and T-lymphocyte leukemia cells were most sensitive (50% inhibitory concentration, 6-11 nM), but B-cell leukemia/lymphoma, melanoma, and ovarian carcinoma cells were at least 10 times more resistant. Bone marrow granulocyte/macrophage progenitors showed intermediate sensitivity. Illudin S was equally effective against CEM T-lymphocyte leukemia cells expressing the multidrug resistance phenotype associated with Mr 180,000 glycoprotein and the parental cell line. CEM cells resistant to doxorubicin, epipodophyllotoxins, and 1-beta-D-arabinofuranosylcytosine showed only a 2-fold increased resistance to illudin S. Illudins are novel and potent cytotoxins which may be preferentially active against human myeloid and T-cell leukemias, including cells resistant to more conventional chemotherapeutic agents. The present studies illustrate the breadth of information which can be obtained on a new agent using present in vitro screening procedures and human cells.     

Mild interoceptive stressors affect learning and reactivity to contextual cues: toward understanding the development of unexplained illnesses.

Contextual learning is evident with repeated experiences with agents and treatments that induce frank illness and interoceptive stress. Here, we examined whether acute treatment with mild interoceptive stressors (low doses of pyridostigmine bromide (PB), neostigmine bromide (NB), and interleukin (IL)-1beta) may serve as unconditional stimuli supporting contextual learning. Rats were exposed to interoceptive and exteroceptive stressors in contexts distinguished by visual or olfactory cues. Acoustic startle responses (ASRs) were measured the day following exposure and 2 weeks thereafter, without delivery of the unconditional stimuli. The appearance, form, and duration of startle potentiation depended on the distinguishing features of the context and the nature of the interoceptive stressor. Rats given cholinesterase inhibitors (PB and NB), but not IL-1beta or exposed to an exteroceptive stressor, exhibited exaggerated ASRs in a novel context distinguished by visual cues. Treatment with either PB or IL-1beta led to potentiated ASRs in the presence of odors congruent with those experiences during exposure to the stressor. Startle potentiation by odor was still apparent 2 weeks after treatment. For contexts differentiated by visual stimuli, cholinomimetics transiently alter reactivity within novel contexts. In the case of contexts differentiated by odors, learning is apparent at least 2 weeks after acute treatment of cholinomimetics and IL-1beta. Contextual learning and changes in reactivity consequent to mild interoceptive stressors such as PB may play a role in the development of nonspecific symptoms typical of unexplained illnesses, such as Gulf War Illness.     

In vitro modulation and relationship between N-myc and HLA class I RNA steady-state levels in human neuroblastoma cells.

Neuroblastoma cell lines and tumors are characterized by low HLA class I expression. The majority of neuroblastoma cell lines and a high percentage of disseminated tumors display amplification of the nuclear protooncogene N-myc. An inverse correlation between HLA class I expression and N-myc amplification and overexpression has been recently described in neuroblastomas (NBs). In this study we have shown that cytokines (recombinant gamma-interferon, recombinant alpha-tumor necrosis factor), differentiation agents (dibutyryl cyclic AMP, phorbol myristate acetate) and growth factors (nerve growth factor, epithelial growth factor) were able to influence the growth rate and surface expression of HLA class I molecules as well as of a tumor-associated antigen on 2 representative NB cell lines. Induced decreased growth rate in NB cells was not always related to decreased N-myc expression. Analysis at the mRNA level revealed that both N-myc and HLA class I RNA steady-state levels could be modulated by several substances, including recombinant gamma-interferon, phorbol myristate acetate, dibutyryl cyclic AMP, and epithelial growth factor and were not necessarily linked. An inverse correlation between N-myc and HLA mRNA levels was observed only after exposure of NB cells to recombinant alpha-tumor necrosis factor. We conclude that N-myc and HLA class I RNA steady-state levels can be modulated independently and suggest that they are not necessarily inversely regulated.     

Recurrent renal cell carcinoma arising in Wilms' tumor.

A 19-month-old black girl had a radical nephrectomy for a Wilms' tumor that contained areas of epithelium indistinguishable from renal cell carcinoma. She was treated with chemotherapy but subsequently had pulmonary metastases develop and massive abdominal recurrence. The recurrent tumor was histologically renal cell carcinoma with no identifiable Wilms' tumor elements. The child died with recurrent and metastatic tumor 13 months after nephrectomy. Pathologic, immunoperoxidase, and flow cytometric studies of this unusual case are presented.     

House dust mites and human dander

The occurrence of house dust mites was measured in the homes of 12 patients with the scaly skin disease, psoriasis. The median number of mites in the mattress dust and floor dust was 27 (range 10-153)/0.1 g and 56 (range 12-114)/0.1 g respectively, which is significantly higher than the background pollution of house dust mites in normal Danish homes. The results support the idea that the amount of mites in our homes not only depend on relative air humidity but also on the production of dandruff.     

A rare case of an epigastric fistula

The authors report on a 75-year-old man who had been operated on 50 years before because of a gastric perforation. Since then he had had no symptoms. Two weeks before visiting the doctor he had noticed a 2-mm fistula in the epigastric region. Symptomatic therapy prescribed by the general practitioner had no result. On fistulography a complete gastric fistula was diagnosed. X-ray examination of the stomach showed an area highly suggestive of gastric cancer in the antrum region. Surgical examination revealed a 6-cm-long thread with concomitant, enormously extensive granuloma.     

A comparison of the teaching effectiveness of the didactic lecture and the problem-oriented small group session: a prospective study

A prospective study was designed to assess the teaching effectiveness of active learning in problem-oriented small group sessions (POSGS) compared with passive learning in didactic lectures (DL). Third-year medical students participated in a POSGS on breast disease and a standardized DL on thyroid disease (N = 23) or participated in a POSGS on thyroid disease and a DL on breast disease (N = 19). Students were tested with a multiple-choice examination (MCQ) and a highly structured oral examination (OE) administered by faculty members blinded about student group. Results of a between-within analysis of variance performed separately for breast and thyroid disease yielded significant group differences because of instructional method for thyroid disease (p = 0.003) and approached significance for breast disease (p = 0.095). Although no significant interactions were detected with percentage scores, a significant interaction between group membership and test type was noted for thyroid disease when the percentage scores were transformed to Z scores. We conclude that regardless of topic or testing method, students in POSGS tended to perform better than students in a DL and that the POSGS offers significant advantages over the DL in teaching surgery to third-year medical students.     

Rapid dissipation of glyphosate in small forest ponds

Glyphosate was applied to the water surface of four small boreal forest ponds and sixin situ microcosms at a rate of 0.89 Kg a.i./ha. Water samples collected over a period of up to 255 days were analyzed for glyphosate and its primary metabolite aminomethylphosphonic acid (AMPA). Glyphosate dissipated rapidly from all ponds with first order half-lives ranging from 1.5 to 3.5 days. The slowest dissipation rate occurred in the pond with the most calcareous water and sediments. Glyphosate remained at or above the treatment concentration in microcosms containing only water but decreased rapidly in the presence of sediments. AMPA levels in ponds and microcosms were consistently low. Concentrations on microcosm wall samples were temporally variable, probably a result of adsorption to periphytic biofilms. Glyphosate in the sediments of treated microcosms generally increased with time during the period of observation. These results confirm that glyphosate dissipates rapidly from the surfaces waters of lentic systems, and suggest that sediment adsorption or biodegradation were the major means of glyphosate loss from the water column.     

Acute appendicitis. A 5-year review

A startling 31 per cent rate of perforated appendicitis in 1984 prompted a 5-year review at the Guthrie Medical Center. An increase over previous rates of 13 per cent and 0 per cent in 1964 and 1944 was confirmed in this study. Perforation accompanied 44 of 240 cases of appendicitis (18.3%); diagnostic accuracy in 295 cases undergoing operation was 81.4 per cent. Groups at risk for perforation were patients in the first decade of life (34.3% with perforations) and those over 50 years of age (48% perforated). Perforation rates were generally inversely related to accuracy. Accuracy was poorest in women in the second to fourth decade or those in the mid-portion of the menstrual cycle. When the appendix was not perforated, complications occurred in 8.7 per cent of patients while 29.5 per cent with a perforation had a complication. The mean hospital stay was prolonged by 2.5 days if the appendix was perforated. An increased awareness of the risk by both the public and physicians is essential to reduce the number of perforations.     

Behavioural profile of partial D2 dopamine receptor agonists

The effects of partial D2 dopamine (DA) receptor agonists on the behavioural activation produced by 1.5 and 8.0 mg/kgd-amphetamine were compared with the changes produced by the classical DA antagonist haloperidol. Alterations in behaviour were assessed in standard activity monitoring cages by direct observation of the rats using a rapid time sampling procedure. Haloperidol blockedd-amphetamine (1.5 mg/kg)-induced increases in photocell counts, ambulation, rearing and sniffing up, and after the highest dose of the DA antagonist the animals were mainly inactive. The partial D2 DA agonist SDZ 208–911 was equipotent to haloperidol in blocking the increase in photocell counts and rearing produced byd-amphetamine. However, even high doses of the drug did not reduce the incidence of sniffing or induce inactivity, but qualitative changes in the form of sniffing did occur. Although considerably less potent, preclamol exerted similar effects to SDZ 208–911. The profiles of SDZ 208–912 and terguride were intermediary to those of SDZ 208–911 and haloperidol. All compounds blocked the repetitive sniffing down produced by 8.0 mg/kgd-amphetamine. After a low dose of haloperidol, these stereotyped behaviours were replaced by a behavioural syndrome similar to that observed with low dosed-amphetamine, but inactivity was observed following a further small increase in antagonist dose. The blockade of stereotypy by SDZ 208–911, preclamol and terguride was accompanied only by the low dosed-amphetamine behavioural syndrome; no inhibition of sniffing or induction of inactivity occurred. SDZ 208–912 exhibited a profile with features very similar to that noted with haloperidol. These findings suggest that partial D2 agonists exert similar, but not identical, behavioural effects to classical DA antagonists when dopaminergic function in increased byd-amphetamine. The differences in behavioural profile are discussed in relation to variations in the intrinsic efficacy of the dopaminergic compounds and to differences in the response capability of D2 receptor populations underlying the different behaviours produced byd-amphetamine.