Prolonged episodes of persistent asthma: A distinct clinical pattern with characteristic clinical features

STUDY OBJECTIVES

To investigate a clinical pattern of unexplained persistent asthma that is episodic in nature and lasts for months to years. This pattern of prolonged episodes of unexplained, persistent asthma was not defined previously.

DESIGNS

Investigating the clinical features using a retrospective cohort design.

SETTING AND PATIENTS

Eighteen subjects (ages, 13 to 64 years) from an allergy practice in a large prepaid health maintenance organization who had two or more prolonged episodes of unexplained persistent asthma lasting >/= 2 months during a 12-year period.

RESULTS

These subjects accounted for 39 asthmatic episodes lasting from 2 to 74 months (median, 7 months). The duration of the episodes positively correlates with the severity of asthma (p = 0.02) at the initial part of the episodes. All episodes demonstrated a similar pattern, with symptom severity greatest at the onset and gradually diminishing until recovery. The relatively symptom-free intervals between the episodes ranged from 1.5 to 63 months (median, 13 months). Fifty-six percent of the episodes (95% confidence interval [CI], 40% to 72%) were associated with symptoms very suggestive or suggestive of an infection of the upper respiratory tract at the onset of the episodes; 33% of the episodes (95% CI, 19% to 50%) had possible symptoms suggestive of an infection; whereas only 10% of the episodes (95% CI, 3% to 24%) had questionable or no symptoms suggestive of an infection of the upper respiratory tract. Thirty-four episodes had the onset between September and March, whereas only 5 episodes occurred between April and August (p < 0. 001).

CONCLUSIONS

These observations indicate that prolonged episodes of unexplained, persistent asthma lasting for months to years constitute a distinct clinical pattern of asthma with characteristic clinical features.

Dissociation of the high density lipoprotein and low density lipoprotein binding activities of murine scavenger receptor class B type I (mSR-BI) using retrovirus library-based activity dissection

The murine class B, type I scavenger receptor (mSR-BI) is a receptor for both high density lipoprotein (HDL) and low density lipoprotein (LDL) and mediates selective, rather than endocytic, uptake of lipoprotein lipid. We have developed a "retrovirus library-based activity dissection" method to generate mSR-BI mutants in which some, but not all, of the activities of this multifunctional protein have been disrupted. This method employs three techniques: 1) efficient in vitro cDNA mutagenesis (here error-prone PCR was used), 2) efficient retroviral delivery and high expression of single mutant cDNAs into individual cells, and 3) isolation of infected cells expressing the desired mutant phenotype using high sensitivity positive/negative screening by two-color fluorescence-activated cell sorting. A set of mutants, all having arginine substitutions at two common sites (positions 402 or 401 and position 418), were isolated and characterized. Mutation at either site alone did not generate as strong a mutant phenotype (loss of DiI uptake from DiI-HDL) as did the double mutations. "Activity-dissected" double mutants were as effective as wild-type mSR-BI in functioning as LDL receptors, mediating high affinity LDL binding and uptake of metabolically active cholesterol from LDL, but they lost most of their corresponding HDL receptor activity. Thus, these mutants provide support for the proposal that the interaction of SR-BI with HDL differs from that with LDL. Examination of the in vivo function of such mutants may provide insights into the differential roles of the LDL and HDL receptor activities of SR-BI in normal lipoprotein metabolism and in SR-BI's ability to protect against atherosclerosis.

Effect of telomere and telomerase interactive agents on human tumor and normal cell lines

Shortening of telomeres along with an up-regulation of telomerase is implicated in the immortality of tumor cells. Targeting either telomeres or telomerase with specific compounds has been proposed as an anticancer strategy. Because telomerase activity and telomeres are found in normal cells, telomere or telomerase targeting agents could induce side effects in normal tissues. We evaluated the effects of telomere and telomerase interactive agents in human tumor and normal cell lines to try to determine the potential side effects those agents might induce in patients. Toxicity of the G-quadruplex interactive porphyrins (TMPyP4, TMPyP2) and azidothymidine (AZT) were tested using a cell-counting technique against normal human cell lines (CRL-2115 and CRL-2120, fibroblasts; NHEK-Ad, adult keratinocytes; CCL-241, small intestinal cells; NCM 460, colonic mucosal epithelial cells) and human tumor cell lines (MDA-MB 231 and Hs 578T, breast cancer; SK-N-FI, neuroblastoma; HeLa, cervix cancer; MIA PaCa-2, pancreatic cancer; HT-29 and HCT-116, colon cancer; DU 145, prostatic cancer cell line). Telomerase activity of these cell lines was measured by a non-PCR-based conventional assay. The effects of TMPgammaP2, TMPyP4, and AZT were also evaluated against normal human bone marrow specimens, using a granulocyte-macrophage colony-forming assay (CFU-GM). AZT showed very low cytotoxic effects against normal and tumor cell lines, with the IC50 values above 200 microM. The IC50 values for TMPyP2 and TMPyP4 in normal human cell lines were in the range of 2.9-48.3 microM and 1.7-15.5 microM, respectively, whereas in tumor cell lines the IC50 values were 11.4-53 microM and 9.0-28.2 microM, respectively. Within the tissue types, keratinocytes were more sensitive to TMPyP4 than fibroblasts, and small intestinal cells were more sensitive than colonic mucosal epithelial cells. The IC50 for TMPyP2 and TMPyP4 in the normal marrow colony-forming assays were 19.3 +/- 5.1 microM and 47.9 +/-1.0 microM, respectively. In conclusion, the in vitro cytotoxicity of the telomere interactive agent TMPyP4 is comparable in human tumor and normal cell lines, which indicates that TMPyP4 could have effects on normal tissues.

Office prenatal formula advertising and its effect on breast-feeding patterns

OBJECTIVE

To compare the effect of formula company-produced materials about infant feeding to breast-feeding promotion materials without formula advertising on breast-feeding initiation and duration.

METHODS

Five hundred forty-seven pregnant women were randomized to receive either formula company (commercial; n = 277) or specially designed (research; n = 270) educational packs about infant feeding at their first prenatal visit. Feeding method was determined at delivery. Breast-feeding duration of the 294 women who chose to breast-feed was ascertained at 2, 6, 12, and 24 weeks. Survival analyses were used to evaluate continuous outcomes, and chi2 and logistic regression analyses were used to evaluate discrete outcomes.

RESULTS

Breast-feeding initiation (relative risk [RR] 0.93, 95% confidence interval [CI] 0.61, 1.43) and duration after 2 weeks (hazard ratio 1.19, 95% CI 0.86, 1.64) were not affected. Women in the commercial group were more likely to cease breast-feeding before hospital discharge (RR 5.80, 95% CI 1.25, 54.01) and before 2 weeks (adjusted odds ratio [OR] 1.91, 95% CI 1.02, 3.55). In subgroup analyses, women with uncertain goals for breast-feeding or goals of 12 weeks or less experienced shortened exclusive (hazard ratio 1.53, 95% CI 1.06, 2.21), full (hazard ratio 1.70, 95% CI 1.18, 2.48), and overall (hazard ratio 1.75, 95% CI 1.16, 2.64) breast-feeding duration when exposed to the commercial intervention.

CONCLUSION

Although breast-feeding initiation and long-term duration were not affected, exposure to formula promotion materials increased significantly breast-feeding cessation in the first 2 weeks. Additionally, among women with uncertain goals or breast-feeding goals of 12 weeks or less, exclusive, full, and overall breast-feeding duration were shortened. Educational materials about infant feeding should support unequivocally breast-feeding as optimal nutrition for infants; formula promotion products should be eliminated from prenatal settings.

Immunologic and virologic responses to HAART in severely immunocompromised HIV-1-infected children

OBJECTIVE

To determine the long-term immunologic and virologic effects of highly active antiretroviral therapy (HAART) in children with AIDS.

DESIGN

A prospective observational study.

SETTING

Two pediatric HIV clinics.

PARTICIPANTS

Twenty-five protease-inhibitor naive HIV-infected children (aged 2-18 years) with advanced disease (CD4 < or =6%).

INTERVENTION

HAART (one protease inhibitor and one or more nucleoside analogs). Diphtheria and tetanus immunization in six patients after 18 months of therapy.

MAIN OUTCOME MEASURES

Changes in percentage of CD4 cells and plasma HIV-1 RNA levels; post-treatment assays of lymphoproliferative responses to recall antigens; CD4 cell memory phenotype.

RESULTS

Median duration of follow-up was 18.8 months (range, 7.5-28 months). At baseline the CD4 cell percentage was 2% (range, 0-6%), this increased significantly to 16% (range, 3-48%) above baseline at 12 months (P = 0.002). The mean maximum CD4 cell increase was 20.7% (range 4-48%) which corresponds to 657x10(6) cells/l (range, 30-2240x10(6) cells/l) above baseline. By contrast, the median viral load was not significantly lower at 12 months than at baseline (P = 0.34), and only 25% of the patients had sustained undetectable viral load. Of the reconstituted CD4 cells 70% were naive, and none of the subjects had lymphoproliferative responses to tetanus and diphtheria although 40% did develop responses to Candida, an environmental antigen. A single immunization with diphtheria and tetanus toxoid produced lymphoproliferative responses to tetanus in three out of six patients.

CONCLUSIONS

HAART was associated with sustained increases in CD4 cell counts, despite a high incidence of 'virologic failure'. CD4 counts and the proportion of naive cells were higher than have been reported in adults, which may be a reflection of greater thymic activity in children. Memory cell clones for antigens encountered in the past which are not prevalent before therapy could not be expanded without additional antigenic exposure.

Induction of apoptosis and apoptotic mediators in Balb/C splenic lymphocytes by dietary n-3 and n-6 fatty acids

The present study was designed to investigate the effect of dietary n-6 and n-3 polyunsaturated fatty acids (PUFA) on anti-CD3 and anti-Fas antibody-induced apoptosis and its mediators in mouse spleen cells. Nutritionally adequate semipurified diets containing either 5% w/w corn oil (n-6 PUFA) or fish oil (n-3 PUFA) were fed to weanling female Balb/C mice, and 24 wk later mice were sacrificed. In n-3 PUFA-fed mice, serum and splenocyte lipid peroxides were increased by 20 and 28.3% respectively, compared to n-6 PUFA-fed mice. Further, serum vitamin E levels were decreased by 50% in the n-3 PUFA-fed group, whereas higher anti-Fas- and anti-CD3-induced apoptosis (65 and 66%) and necrosis (17 and 25%), compared to the n-6 PUFA-fed group, were found when measured with Annexin V and propidium iodide staining, respectively. In addition, decreased Bcl-2 and increased Fas-ligand (Fas-L) also were observed in the n-3 PUFA-fed group compared to the n-6 PUFA-fed group. No difference in the ratio of splenocyte subsets nor their Fas expression was observed between the n-3 PUFA-fed and n-6 PUFA-fed groups, whereas decreased proliferation of splenocytes was found in n-3 PUFA-fed mice compared to n-6 PUFA-fed mice. In conclusion, our results indicate that dietary n-3 PUFA induces higher apoptosis by increasing the generation of lipid peroxides and elevating Fas-L expression along with decreasing Bcl-2 expression. A reduced proliferative response of immune cells also was observed in n-3 PUFA-fed mice.

Activity of the multitargeted antifolate LY231514 in the human tumor cloning assay

PURPOSE

This study was performed to evaluate the activity of the multitargeted antifolate (MTA or LY231514) against a broad range of human tumors taken directly from patients.

MATERIALS AND METHODS

Human tumor colony-forming units were treated with MTA at concentrations of 0.1, 1.0, and 10 microg/ml in 1-h exposure studies. The responses of a limited number of specimens were also evaluated concurrently in 1-h exposures to cisplatin, fluorouracil, irinotecan, and/or paclitaxel.

RESULTS

Of 358 specimens plated in the 1-h exposure studies, 148 (41%) were evaluable. Overall, responses were observed in 3% of specimens (4/144) at 0.1 microg/ml, 11% (17/148) at 1.0 microg/ml, and 23% (33/141) at 10 microg/ml. In this range of concentrations achievable clinically, there was a significant concentration-response relationship. At 10 microg/ml in the 1-h exposure studies, the response rate in colorectal cancer specimens was 32% (9/28), and the response rate in non-small-cell lung cancer was 25% (6/24). Responses were also observed in several chemoresistant tumors, including renal cell carcinoma, hepatocellular carcinoma, mesothelioma, and pancreatic carcinoma. The activity of MTA was not completely cross-resistant with that of cisplatin, fluorouracil, irinotecan, and paclitaxel.

CONCLUSIONS

MTA demonstrated in vitro activity against a spectrum of tumors, including several tumors generally considered chemoresistant.

Effects of SW 33377, SW 68210 and SW 71425 thioxanthones on in vitro colony formation of freshly explanted human tumor cells

Thioxanthones are aromatic hydrocarbons with cytotoxic activity against several tumor models. Potential mechanisms of action may include DNA intercalation, inhibition of nucleic acid biosynthesis, and topoisomerase inhibition, as well as formation of intracellular DNA single strand breaks. Such a broad spectrum of expected antitumor activity makes this class of compounds particularly interesting and worth pursuing in clinical studies. SW 33377 (Win 33377, SR 233377) was so promising in vitro that it was taken into Phase I clinical trials for further evaluation. The compound had undesirable cardiac effects, so new analogs were sought that would have similar antitumor effects without the undesirable side effects. In the present study, two new analogs SW 68210 (WIN 68210), and SW 71425 (WIN 71425) are compared to the antiproliferative action of SW 33377 against a variety of freshly explanted human tumor specimens using an in vitro soft agar cloning system. All compounds were more effective with continuous exposure than 1 hour exposure and a concentration-response effect was evident with all compounds. SW 68210 with continuous exposure showed similar activity to SW 33377 at all concentrations. SW 71425 with continuous exposure was less effective at the lower concentrations but was nearly as effective at 10 microg/ml as the other two compounds and was highly effective at 50 microg/ml. At the 10 microg/ml concentration all compounds were similarly effective against breast, colon, non-small cell lung, and ovarian tumors. The two new analogs, SW 68210 and SW 71425 have activity similar to SW 33377 and are both likely candidates for further development.

Linear free-energy model description of the conformational stability of uracil-DNA glycosylase inhibitor A thermodynamic characterization of interaction with denaturant and cold denaturation

The equilibrium unfolding of uracil DNA glycosylase inhibitor (Ugi), a small acidic protein of molecular mass 9474 Da, has been studied by a combination of thermal-induced and guanidine hydrochloride (GdnCl)-induced denaturation. The analysis of the denaturation data provides a measure of the changes in conformational free energy, enthalpy, entropy and heat capacity DeltaCp that accompany the equilibrium unfolding of Ugi over a wide range of temperature and GdnCl concentration. The unfolding of Ugi is a simple two-state, reversible process. The protein undergoes both low-temperature and high-temperature unfolding even in the absence of GdnCl but more so in the presence of denaturant. The data are consistent with the linear free-energy model and with a temperature independent DeltaCp over the large temperature range of unfolding. The small DeltaCp (6.52 kJ.mol-1.K-1) for the unfolding of Ugi, is perhaps a reflection of a relatively small, buried hydrophobic core in the folded form of this small monomeric protein. Despite a relatively low value of DeltaG(H2O), 7.40 kJ.mol-1 at pH 8.3, Ugi displays considerable stability with the temperature of maximum stability being 301.6 K.

Cytotoxic effects of MGI 114 are independent of tumor p53 or p21 expression

MGI 114, an analog of illudin S, shows potent activity against a broad range of human tumors in vitro and in vivo, including drug resistant tumors. In this study we examined cytotoxicity of MGI 114 against human tumor cell lines (MCF7, MDA.MB.468, EJ1, J82, SCaBER, KG-1, HL60, and IMR-90) with differing expression of p53 and/or p21 (WAF1) tumor suppressor genes. Only MCF7 and IMR-90 express the wild type p53, WAF1 is present in high levels in MCF7 and SCaBER. WAF1 expression can be induced in KG-1, HL60, and IMR-90. The cells were treated with MGI 114 at 0.1, 1.0 and 10 micrograms/ml in 1 h exposure and with 0.01, 0.1 and 1.0 microgram/ml MGI 114 in a continuous exposure. Cell numbers were measured at days 2, 4, and 7. MGI 114 suppressed growth in all cell lines at day 2 after 1 h exposure at the two highest concentrations and at all concentrations in a continuous exposure. Some cells partly recovered from the inhibition by day 4. Expression of WAF1 had no apparent effect on growth suppression by MGI 114, however, cells with inducible WAF1 showed slower recovery from MGI 114 inhibition in comparison with the cells under non-permissive conditions. Overall, MGI 114 effectively inhibited growth of human cancer cells regardless of their p53 and WAF1 status.

Recombinant human interleukin-11 is unlikely to stimulate the growth of the most common solid tumors

Recombinant human interleukin-11 (rhIL-11) has been shown to enhance recovery from thrombocytopenia and mucosal injury after cancer chemotherapy. Since RNA for the receptor and signal transducer for IL-11 is detected in many cell types including some cancer cells, it was theoretically possible that rhIL-11 could affect the growth of tumor cells. This study was intended to determine whether rhIL-11 stimulates the proliferation of human tumor colony-forming units (TCFUs) taken directly from patients. Tumor cells were cultured in soft agar and continuously exposed to three concentrations of rhIL-11 (1.0, 10.0 and 100.0 U/ml) for 14 days in the capillary cloning system. Growth stimulation was noted in two of 66 (3%) of evaluable specimens, including one of 14 evaluable non-small cell lung cancer and one of five evaluable colon cancer specimens. In these two specimens, there was no increased stimulation of TCFUs with escalating concentrations of rhIL-11. Interestingly, the highest concentration of rhIL-11 tested inhibited the growth of 16 specimens (24.2%; 95% confidence interval 13.9-34.5%). Growth inhibition demonstrated a concentration-response relationship (p < 0.001). These results suggest that rhIL-11 appears unlikely to stimulate the growth of the most common solid tumors.

Development and comparison of iron dextran products

Iron dextran complex has existed as a parenteral drug formulation for forty years. Two new formulations of this prodrug became available after an older form was withdrawn from distribution in the United States. Molecular weight, lot-to-lot consistency and thermal stability were examined among these three complex formulations using HP-GPC analysis. Also, particle size measurements using transmission electron microscopy and reduction degradation kinetics were determined. In each mode of analysis, substantial differences were observed among the three preparations with variability and sensitivity to stress (either thermal or acid) decreasing from the oldest form (no longer available) to the next offered complex (Mw of 90 kd +/- 7.5%) to the most recently approved complex (Mw of 265 kd +/- 1.5%). These findings support an iron dextran complex produced by improved techniques and higher manufacturing quality standards with less variability and more reproducibility.

In vitro antitumor activity of the novel marine agent, ecteinascidin-743 (ET-743, NSC-648766) against human tumors explanted from patients

BACKGROUND

Ecteinascidin-743 (ET-743), a member of the ecteinascidin family selected for clinical development, is a tetrahydroisoquinolone alkaloid isolated from the marine ascidian, Ecteinascidia turbinata. This novel compound is a minor groove binding, guanine-specific alkylating agent which also interacts with the microtubule network and blocks cell cycle progression at late S/G2.

MATERIALS AND METHODS

A soft agar cloning assay was used to determine the in vitro effects of ET-743 against primary human tumor specimens taken directly from patients. A total of 93 evaluable specimens were exposed to ET-743 for one-hour (n = 25) and/or 14-day continuous exposure (n = 92) at concentrations ranging from 0.1 nM to 1 microM. In vitro responses were defined as an inhibition > or = 50% of human tumor colony forming units at a given concentration.

RESULTS

One-hour exposure to ET-743 at concentrations of 0.1 nM, 1 nM, 10 nM, 100 nM and 1 microM induced in vitro responses in 0% (0/17), 6% (1/17), 16% (4/25), 13% (1/8), and 25% (2/8) of specimens, respectively. Continuous exposure to ET-743 at concentrations of 0.1 nM, 1 nM, 10 nM, 100 nM and 1 microM, inhibited 0% (0/16), 13% (2/16), 49% (44/90), 62% (47/76), and 77% (58/75) of tumor specimens, respectively. Tumor-specific responses and concentration-dependent relationships were observed with a continuous exposure to ET-743. At 100 nM, the compound inhibited 79% (11/14) breast, 69% (9/13) non-small-cell lung, 58% (7/12) ovary, and 88% (7/8) melanoma specimens. At 1 microM, ET-743 inhibited 100% (14/14) breast specimens, 85% (11/13) non-small-cell lung, 67% (8/12) ovary and 86% (6/7) melanoma specimens. Activity of ET-743 at and above 10 nM was also observed against sarcoma and kidney tumors. At 10 nM concentration and continuous exposure ET-743 demonstrated incomplete cross-resistance with paclitaxel, alkylating agents, doxorubicin and cisplatin.

CONCLUSIONS

Our data from the cloning assay indicate that the duration of exposure to ET-743 is an important factor in human tumors. Therefore, long-term exposure to ET-743 may be preferred in future clinical trials. The activity of ET-743 in breast, non-small-cell lung, and ovarian cancers as well as in melanoma may deserve further clinical evaluations. The potential of ET-743 in sarcoma and renal tumors might also be considered. In addition, our data indicate that a plasma concentration of 100 nM of ET-743 must be considered as a target during the clinical development of the compound; also the concept of continuous/protracted exposure in clinical trials with ET-743 has to be taken into account.

Activity of (-)-2'-deoxy-3'-oxacytidine (BCH-4556) against human tumor colony-forming units

BACKGROUND

BCH-4556 ((-)-2'-deoxy-3'-oxacytidine) is an L-nucleoside analogue shown to have broad preclinical anti-cancer activity, particularly against solid neoplasms such as prostate, renal, and hepatoma in vitro and in vivo, in contrast to cytosine arabinoside (ara-C) which is preferentially active against leukemia.

MATERIALS AND METHODS

The antitumor activity of BCH-4556 was evaluated using human tumor colony-forming unit (HTCFU) assay, in which fresh tumor specimens were taken directly from patients with and without prior chemotherapy.

RESULTS

Overall, in vitro responses (50% or less survival compared to untreated controls) were observed in 11% (two of 18), 29% (five of 17) and 50% (nine of 18) of specimens treated for one hour with BCH-4556 at 1, 10 and 100 micrograms/ml, respectively; and 16% (nine of 55), 32% (24 of 74), 48% (35 of 73) and 65% (11 of 17) of specimens treated continuously with BCH-4556 at 0.1, 1, 10 and 100 micrograms/ml, respectively. With the one-hour schedule, a significant difference in response rates was noted between 100 micrograms/ml and 1 microgram/ml (P = 0.02). With the continuous schedule, significant differences in response rates were observed between 1 microgram/ml and 0.1 microgram/ml (P = 0.02), between 10 micrograms/ml and 0.1 microgram/ml (P = 0.0001), as well as between 10 micrograms/ml and 1 microgram/ml (P = 0.01). A trend suggesting the superiority of continuous exposure was observed in paired specimens (n = 18) at comparable drug concentrations. Activity was noted against ovarian (nine of 16 = 56%), renal (three of four = 75%), and melanoma (two of two = 100%) HTCFU at 10 micrograms/ml using the continuous schedule. Comparisons between BCH-4556 and paclitaxel were made in 32 specimens at 10 micrograms/ml using the continuous exposure. Twenty-three specimens showed similar responses with both drugs; seven showed better responses with BCH-4556; and two showed better responses with paclitaxel (P = 0.18).

CONCLUSIONS

Promising activity was observed with BCH-4556 against ovarian, renal, and melanoma HTCFU. There appeared to be a positive relationship between BCH-4556 concentration and response using both one-hour and continuous exposures. Continuous exposure to BCH-4556 provided high response rates especially at concentrations above 10 micrograms/ml. For both one-hour and continuous exposures, BCH-4556 had similar, and at times, greater potency than paclitaxel against the same tumor specimens in the present study.

Dimethyl sulfoxide (DMSO) causes a reversible inhibition of telomerase activity in a Burkitt lymphoma cell line

INTRODUCTION

Telomerase is an enzyme that is required for maintenance of telomeres. This enzyme has been shown to be present in germline tissues and majority of tumors and tumor cell lines. The regulation of telomerase is an area of active investigation in different models because, potentially, inhibition of this enzyme could be important in cancer therapy. To study the regulation of this enzyme in lymphoma cell lines, we used DMSO to produce a reversible G0/G1 arrest in Raji cell line, as shown earlier [Sawai M, Takase K, Teraoka H, Tsukada K. Reversible G1 arrest in the cell cycle of human lymphoid cell lines by dimethyl sulphoxide. Exp Cell Res 1990;187:4-10].

METHODS

In this study, we use a highly quantifiable conventional (non-amplified) assay to study the effect of DMSO on telomerase. In addition, we studied cellular proliferation and cell cycle profiles of the cells treated and, subsequently, released from DMSO induced blockage.

RESULTS

In this model, DMSO reversibly inhibited telomerase activity that could be restored after release from the blockage. The inhibition of telomerase seems to parallel cellular proliferation and it appears that telomerase is regulated upon entry into the cell cycle. This view is consistent with other previously published views on relationship of telomerase with exit from cell cycle.

CONCLUSION

Our observations demonstrate a novel effect of DMSO on cellular mechanisms in Raji cell line. It may provide an attractive model to further study regulation of telomerase in this cell line.

An in vitro assessment of the antineoplastic potential of 2H-1,3-oxazine-2,6(3H)-dione (3-oxauracil), a novel pyrimidine

The pyrimidine (uracil) analogue 3-oxauracil (OU) previously had been shown to completely inhibit the growth of E. coli B and decrease by 96% the replication of herpes simplex virus type 2 when present in the culture fluid at a concentration of 10(2) microM. Limited in vivo studies in mice demonstrated antiviral effects without significant toxicity when given i.p. daily for two weeks at a concentration of 3.23 mg/kg. However, the antineoplastic properties of OU were unknown. We assessed the ability of OU to inhibit the proliferation of various human tumor cell lines (3 pancreatic, 1 colon, 1 neuroendocrine, and 1 lung) in an in vitro radiometric (Bactec) system. In the pancreatic lines (RWP-2, MiaPaCa-2, and PANC-1), the colon line (HT-29), the neuroendocrine line (COLO 320DM), and the lung cancer cell line (SK-MES-1), OU at a concentration of 10(3) microM, produced a dramatic decrease in percent cell survival. When compared with cytotoxic drugs of choice for these tumor cells (gemcitabine, 5-fluorouracil, and adriamycin, respectively) a significantly higher concentration of OU was required usually to achieve comparable results with two exceptions. These were the HT-29 and the COLO 320DM cell lines. These results indicate OU has significant (p < 0.05) cytotoxic activity against pancreatic, colon, neuroendocrine, and nonsmall cell lung cancer lines, when compared to untreated control cultures. Additional in vivo testing of this potential antineoplastic agent is warranted.

Activity of oxaliplatin against human tumor colony-forming units

This study was conducted to identify tumor types warranting Phase II clinical trials of oxaliplatin using the human tumor cloning assay. Oxaliplatin was tested at concentrations ranging from 0.5 to 50.0 microg/ml in 1-h and 14-day continuous exposures along with 1.4 microg/ml carboplatin and 0.2 microg/ml cisplatin for comparison. We defined in vitro response as tumor growth inhibition >50% of control. In the 1-h exposure schedule, in vitro responses were observed in 9 of 116 (8%), 18 of 115 (16%), 38 of 103 (37%), and 7 of 13 (54%) tumor specimens at concentrations of 0.5, 5.0, 10.0, and 50.0 microg/ml oxaliplatin, respectively. In the 14-day exposure schedule, in vitro responses were observed in 10 of 121 (8%), 37 of 121 (31%), 57 of 106 (54%), and 15 of 15 (100%) tumor specimens at concentrations of 0.5, 5.0, 10.0, and 50.0 microg/ml oxaliplatin, respectively. Activity was observed against colon cancer, non-small cell lung cancer, gastric cancer, and melanoma colony-forming units. In both cisplatin-resistant and cisplatin-sensitive tumors, the activity of oxaliplatin was concentration and time dependent. A 1-h exposure to 5.0 and 10.0 microg/ml oxaliplatin led to 7.4 and 23.4% in vitro responses, respectively, in specimens resistant to 1-h exposure of 0.2 microg/ml cisplatin. Moreover, 1-h exposures to 5.0 microg/ml and 10.0 microg/ml oxaliplatin showed in vitro antitumor responses in 10.2 and 24.3%, 17.2 and 34.5%, 10.0 and 20.0%, 6.7 and 16.7%, and 11.4 and 34.3% of specimens resistant to 1.4 microg/ml carboplatin, 6.0 microg/ml 5-fluorouracil, 3.0 microg/ml irinotecan, 10.0 microg/ml paclitaxel, and 0.04 microg/ml doxorubicin, respectively. The effect in those drug-resistant specimens was improved when oxaliplatin was used on the protracted exposure regimen. Our data indicate that oxaliplatin is an active drug in vitro against a large variety of human tumors. Both concentration and duration of exposure are important factors for oxaliplatin cytotoxicity. The broad spectrum of activity and the in vitro activity against some tumors primarily resistant to conventional anticancer drugs encourage further clinical investigations of oxaliplatin in patients with advanced cancer refractory to conventional chemotherapy.

Antiproliferative effects of recombinant human bone morphogenetic protein-2 on human tumor colony-forming units

Bone morphogenetic protein-2 (BMP-2) is a differentiation factor for normal osteoblasts. BMP-2 is structurally related to transforming growth factor-beta which inhibits cell proliferation and enhances apoptosis. A recent study has shown the presence of BMP-2 receptors on several cancer cell lines. In this study, we attempted to determine if recombinant human BMP-2 (rhBMP-2) can modulate the proliferation of human tumor colony-forming units taken from 113 patients. Tumor cells were cultured in soft agar and continuously exposed to three concentrations of rhBMP-2 (10, 100 and 1000 ng/ml) for 14 days in the capillary cloning system. There were 65 evaluable specimens, including 17 breast cancers, 15 ovarian cancers, 14 non-small cell lung cancers and five prostate cancers. Importantly, rhBMP-2 did not stimulate the tumor cell proliferation. A significant inhibition (50% or less survival of tumor colony-forming units) was seen in 16 of 65 specimens (24.6%) at 1000 ng/ml, including five of 14 non-small cell lung cancers, five of 17 breast tumors and two of 15 ovarian tumors. A concentration-response relationship was observed (p<0.001 by Mantel-extension test). The results of this study encourage further evaluation of the antiproliferative effects of rhBMP-2 against human cancers.