Resistance mechanisms following cisplatin and oxaliplatin treatment of the human teratocarcinoma cell line 2102EP

BACKGROUND

Oxaliplatin and cisplatin are widely used in cancer chemotherapy, however, their clinical efficiency is often limited by the development of resistance.

MATERIALS AND METHODS

We examined different mechanisms of resistance in the human teratocarcinoma cell line 2102EP following exposure to cisplatin or oxaliplatin. Cells were exposed ten times with IC90-doses of 30 microM cisplatin and 50 microM oxaliplatin, respectively. Different cell clones were tested for expression of resistance using the SRB-assay. Moreover, resistance mechanisms in terms of drug uptake, platinum-adduct formation, GSH metabolism, DNA mismatch repair and p53 protein function were investigated.

RESULTS

Three cisplatin cell clones with significant resistance factors of 2.0 to 2.6 were found. Two oxaliplatin cell clones showed only weak resistance, with resistance factors of 1.6 and 1.7, respectively. In all three cisplatin-exposed cell clones a decreased cellular uptake of cisplatin was found. Furthermore, mechanisms of DNA damage tolerance may also play a role in the development of cisplatin-resistance in these cells. However, only two cell clones showed a decreased level of platinum-DNA-adducts. An increased DNA-repair of platinum-DNA adducts was not seen. In addition, no differences in expression of mismatch-repair proteins MSH2 and MLH1, tumor suppressor protein p53, or glutathione metabolism were found. However, significant resistance mechanisms for the observed oxaliplatin resistance could not be identified, although in one oxaliplatin-exposed cell clone, there was some evidence that a decreased cellular uptake of oxaliplatin may contribute to the observed low level resistance.

CONCLUSIONS

The data add weight to the hypothesis that resistance mechanisms following oxaliplatin exposure may be similar to cisplatin. The precise mechanisms of resistance in the oxaliplatin-resistant cell clones are still not fully understood and current studies are underway to further eluciate this finding.

Saccharic acid 1.4-lactone protects against CPT-11-induced mucosa damage in rats

PURPOSE

To evaluate the ability of D-saccharic acid 1.4-lactone (SAL), a beta-glucuronidase inhibitor, to prevent irinotecan hydrochloride (CPT-11) from inducing mucosal damage as a cause of diarrhea in rats.

METHODS

Wistar rats were divided into six groups of three animals each, administered 1.0 ml isotonic solution intraperitoneally once daily for up to three consecutive days, respectively for up to six days. The series were as follows: (1) On days 1-3: saline; (2) On days 1-3: 200 mg CPT-11/m2; (3) On days -3 to -1 relative to the first administration of CPT-11: 10 mg/ml SAL; on days 1-3: 200 mg CPT-11/m2; (4) On days -3 to +3 relative to the first administration of CPT-11: 10 mg/ml SAL, and on days 1-3: additional 200 mg CPT-11/m2; (5) On days 1-3: 200 mg CPT-11/m2 (0.5 ml) + 10 mg/0.5 ml SAL; (6) On days -3 to -1 relative to the first administration of CPT-11: 3 mg/ml SAL, and on days 1-3: 200 mg CPT-11/m2. Luminal mucosa damage of the small intestine was detected by histology 24 h after the last intraperitoneal application. Peptidase activities of the proximal jejunum were measured by using an in situ perfusion model.

RESULTS

Following intraperitoneal CPT-11 treatment, using conventional histology of paraffin sections, we observed severe mucosal damage. This was reflected by a decrease of the villi/crypt ratio, an increase of apoptotic cells, as well as an increase of mitotic figures in the crypt region. There was a concomitant increased lymphatic infiltration in mucosa of CPT-11 treated rats. This damage pattern could be clearly reduced by co-treatment with the beta-glucuronidase inhibitor, SAL, independent of the treatment schedule. In contrast to our expectations based on previous reports, the intraperitoneal application of CPT-11 alone or in combination with SAL did not cause significant differences in luminal enzyme liberation in comparison with controls in the in situ perfusion assay.

CONCLUSIONS

The beta-glucuronidase inhibitor SAL is able to significantly reduce CPT-11-induced mucosal damage in the small intestine of rats. This observation might soon have a clinical impact for the treatment of patients with CPT-11.

Role of receptor proteins for enterobactin and 2,3-dihydroxybenzoylserine in virulence of Salmonella enterica

Single, double, and triple mutants of an enterobactin-deficient mutant strain of Salmonella enterica serovar Typhimurium were constructed that were defective in the expression of the iron-regulated outer membrane proteins (IROMPs) FepA, IroN, and Cir, which are proposed to function as catecholate receptors. Uptake of naturally occurring and chemically synthesized catecholate molecules by these mutants was assessed in standard growth promotion assays. Unique patterns of uptake were identified for each IROMP; specifically, FepA and IroN were confirmed to be required for transport of enterobactin, and all three proteins were shown to function as receptors for the enterobactin breakdown product 2,3-dihydroxybenzoylserine. The fepA, iroN, and cir alleles were transduced to enterobactin-proficient strains of S. enterica serovar Typhimurium and S. enterica serovar Enteritidis, and the resulting phenotypes were confirmed by analysis of outer membrane protein profiles, by sensitivity to KP-736, a catecholate-cephalosporin conjugate, and by growth promotion tests on egg white agar. Intragastric infections of mice with the S. enterica serovar Typhimurium strains indicated that the parental strain and the fepA iroN double mutant were similarly virulent but that the fepA iroN cir triple mutant was significantly attenuated. Moreover, in mixed infections, the fepA iroN mutant showed similar cecal colonization and invasion of the liver to the parental strain, while the triple mutant showed significantly reduced cecal colonization and no measurable spread to the liver. Infections of 4-day-old chicks with S. enterica serovar Enteritidis strains also indicated that mutation of the fepA iroN genes did not significantly reduce cecal colonization and systemic spread compared with those of the parental strain. The results indicate that, while enterobactin uptake is not essential for the virulence of S. enterica serovars in mouse and chicken infection models, the ability to take up 2,3-dihydroxybenzoylserine via any of the three catecholate siderophore receptors appears to play an important role, since the S. enterica serovar Typhimurium triple mutant was significantly attenuated in the mouse model. Salmochelins appear not to be involved in the virulence of S. enterica.

Failure of activation of caspase-9 induces a higher threshold for apoptosis and cisplatin resistance in testicular cancer

Testicular germ cell cancer is one of the very few cancers that are highly sensitive to and curable by cisplatin-based chemotherapy even in an advanced stage. However, in a few cases resistance to cisplatin occurs and patients subsequently die from progressive disease. The molecular basis for this resistance remains to be determined. Using two cisplatin-sensitive (2102EP and H12.1) and one cisplatin-resistant human testicular germ cell cancer cell line (1411HP), we investigated molecular mechanisms in the induction of apoptosis after cisplatin-treatment focusing on the cleavage and activation of caspase-2, caspase-3, caspase-7, caspase-8, and caspase-9. The cell line 1411HP showed a 3.3-fold cisplatin resistance when compared with the sensitive cell lines 2102EP and H12.1 by IC(90)s, which was treatment schedule independent (2- or 24-h incubation). Cisplatin resistance was associated with substantially decreased apoptosis in vitro and in derived nude mice xenografts as determined by Apo 2.7 detection, DNA-laddering, immunohistochemistry of active caspase-3, and terminal deoxynucleotidyl transferase-mediated nick end labeling assay. Total DNA platination as assessed by ELISA after cisplatin treatment in equimolar doses did not differ between cisplatin-resistant or -sensitive cells. In separate analysis of cells of early and late apoptotic stages, initiation of cisplatin-induced apoptosis appeared to be rather mediated by caspase-9 than by caspase-8. Resistant 1411HP cells failed to activate caspase-9 during the induction of apoptosis after cisplatin treatment at the IC(90) dose. Interestingly, inhibition of caspase-9 in sensitive H12.1 almost completely blocked apoptosis and induced cisplatin resistance to the same extent as in 1411HP so that apoptosis could only be induced by 3.3-fold higher cisplatin doses. Furthermore, in caspase-9 blocked cells, initiation of apoptosis occurred in a caspase-9 independent manner accompanied by activation of caspase-2 and caspase-3, which are intrinsic characteristics of resistant 1411HP cells. Failure of caspase-9 activation and cisplatin resistance was independent of the expression of p53, Bcl-2 family proteins, Fas receptor, and Fas ligand. In conclusion, failure of activation of the caspase-9 pathway induces a higher cellular threshold for cisplatin-mediated induction of apoptosis in testicular cancer cells. However, this higher threshold can be overcome by higher cisplatin doses, conceivably by using an alternate, caspase-9-independent apoptotic pathway. This supports the current clinical strategy of high-dose chemotherapy in patients with chemorefractory germ cell tumors. However, additional defining and eventually targeting the exact molecular mechanism blocking caspase-9 activation might lead to more selective therapeutic approaches to overcome cisplatin resistance in germ cell cancer.

Clonal diversity of Shiga toxin-producing Escherichia coli O103:H2/H(-) in Germany

Shiga toxin producing Escherichia coli O103:H2/H(-) belong to the third most frequently isolated EHEC serotypes in Germany following isolates of O157:H7/H(-) and O26:H11/H(-). A total of 145 respective E. coli 103 isolates from single cases of diarrhoea and haemolytic uremic syndrome (HUS) in 1997-2000 were characterised by a range of molecular subtyping methods (PFGE, P-gene profiling, ribotyping, electrotyping) and phage typing in order to analyse their genetic relatedness and the practicability for new epidemiological tracing back. All isolates cluster into a distinct EHEC subgroup and reveal a high clonal diversity together with a considerable stability. Since strains of this serotype rank up to the third most frequently isolated EHEC in Germany a large population of this serotype, and therefore, a great supply of such strains may exist in this country.

A new chemoembolization protocol in refractory liver metastasis of colorectal cancer--a feasibility study

INTRODUCTION

In patients with advanced colorectal cancer (CRC) refractory to systemic chemotherapy including 5-fluorouracil (5-FU) / folinic acid (FA), oxaliplatin and irinotecan we assessed the feasibility, toxicity and response to hepatic transcatheter arterial chemoembolization (TACE). At the time of treatment, patients had exclusively or dominantly liver metastasis of CRC.

PATIENTS AND METHODS

The following protocol was applied via a selective transfemoral hepatic arterial approach: mitomycin C 5 mg/m(2), interferon-alpha2b 4.5 Mio IU, dexamethasone 20 mg mixed with Amilomer DSM 45/25 (Spherex((R))) days 1 and 2 i.a. (bolus), oxaliplatin 50 mg/m(2) (2 h) day 1 i.a., FA 500 mg/m(2) (2 h) day 1 i.v., and 5-FU 1.500 mg/m(2) (24 h) day 1 i.a. Cycles have been repeated at days 15-22. The dose was adjusted according to the pretreatment performance status and elevation of alkaline phosphatase, bilirubin and serum albumin. Treatment was continued until progression or emergence of intolerable toxicity.

RESULTS

11 patients received a total number of 43 TACE, with a range of 2-6 per patient. There was no TACE-related mortality. 4 patients died 5, 8, 10 and 11 months after initiation of treatment due to progression of disease. 7 patients are alive at 4+ (n = 2), 5+ (n = 1), 6+ (n = 1), 7+ (n = 1) and 11+ (n = 2) months after start of treatment. Toxicity (CTC) was mild with grade I-II asthenia (n = 10), grade I-II neurotoxicity (n = 5), grade II nausea and/or vomiting (n = 2) and grade II diarrhea (n = 1). Treatment had to be postponed due to grade I thrombocytopenia in 2 patients. No bleeding episodes or obvious infectious complications occurred during treatment intervals. 1 patient experienced an allergic reaction to oxaliplatin which led to exclusion from further therapy. Arterial catheter dislocation occurred in 3 patients. In 10 patients evaluable for response we observed 3 partial responses, 2 minor responses, and 4 times stable disease. Only 1 patient had further progression of disease under treatment.

CONCLUSION

TACE, using a combination of mitomycin C, dexamethasone and interferon-alpha2b mixed with Spherex((R)), followed by oxaliplatin, FA and 5-FU, appears to be an effective and feasible treatment option in the case of liver metastasis of CRC refractory to standard systemic chemotherapy. This treatment is associated with tolerable toxicity, which becomes apparent mainly as asthenia, neurotoxicity or thrombocytopenia. These preliminary data warrant further evaluation for patients with refractory disease and would probably also be of interest for first-line treatment in this patient population.

Brackiella oedipodis gen. nov., sp. nov., gram-negative, oxidase-positive rods that cause endocarditis of cotton-topped tamarin (Saguinus oedipus)

A gram-negative, oxidase-positive, rod-shaped bacterium isolated from the heart of a cotton-topped tamarin was characterized by 16S rDNA sequence analysis, SDS-PAGE of whole-cell proteins, fatty acid analysis and biochemical tests. Outer-membrane proteins, iron-regulated outer-membrane proteins, lipopolysaccharides and siderophore production were studied. On the basis of the results, the organism belongs to the beta-Proteobacteria where it forms a separate line of descent, for which a novel genus and species are proposed, Brackiella oedipodis (LMG 19451T = DSM 13743T = NCIMB 13739T). Nearest phylogenetic neighbours of the new genus are Taylorella, Pelistega, Bordetella, Alcaligenes and Achromobacter.

Solubility equilibria in multicomponent oceanic salt systems from t = 0 to 200 °C. Model parameterization and databases

In this paper the application of Pitzer's equations for modeling of solubility equilibria in the hexary oceanic salt system Na+, K+, Mg2+, Ca2+ // Cl­, SO42­­H2 O and its subsystems over large temperature intervals is discussed. Lack of ternary solution data considerably restricts the use of the equations as an evaluation tool for the quality of solubility data. Models optimized for the available data in two temperature intervals have been derived. Since Pitzer's model gives no guidance for temperature dependence, the number of parameters is dominated by temperature coefficients. Thus, for extended temperature intervals other approaches like the Cohen-Adad formalism can be advantageous in solubility data evaluation.

HCG induced hyperthyreosis in germ cell cancer

Human germ cell tumors have the unique capacity for totipotential differentiation. AFP (the product of normal yolk sac) and HCG (produced by trophoblastic tissues) are frequently produced by germ cell tumors. The a-subunit of the glycoprotein HCG is identical to that of several pituitary glycoprotein hormones (e.g. TSH, LH, FSH), whereas the b-subunit of HCG, TSH, LH and FSH is homologous but distinct in the terminal amino acid sequence suggesting that HCG is part of a superfamily of gestational hormones. However, the role of TSH within this hormone superfamily is still not yet established. A 24-year old patient was admitted to our clinic because of a widespread recurrence of a germ cell tumor (stage IIIC, Lugano classification). The routine hematologic and blood chemical tests were normal, yet, an elevated HCG was found. In addition, increased levels of the thyroid hormones FT3 and FT4 were seen, although, this was not associated with clinical symptoms of a hyperthyreosis. There was no history of hyperthyreosis and thyroidal autoantibody screening revealed normal titers. An ultrasound examination of the thyroid gland showed no abnormalities and no iodine exposure had occurred during the last months. To mobilize peripheral stem cells (PBSC) he was initially treated with paclitaxel (175 mg/m2) and ifosfamide (8.000 mg/m2)) followed by apheresis of PBSC. The patient was then entered in our phase-II-study for relapsing germ cell carcinomas using a high-dose chemotherapy regime (paclitaxel 175 mg/m2, ifosfamide 9.000 mg/m2, carboplatin 900 mg/m2, etoposide 900 mg/m2) with subsequent retransfusion of collected stem cells. Due to cranial metastases an cranial irradiation was also performed. After three courses of this protocol an excellent partial remission of the tumor lesions was achieved and the HCG value dramatically decreased. Due to elevated thyroidal hormones, the patient was initially treated with thiamazole (20 mg) resulting in decrease of the thyroidal hormones. Thus, the thiamazole dose was reduced to 5 mg and then omitted. The decrease of the thyroidal hormones FT3 and FT4 strongly correlated with the reduction of HCG values (r2 0.91 and 0.77, p < 0.0008). To date there is only slight evidence that enhanced HCG levels may cause, at least in part, a hyperthyreosis (e.g. gestational hyperthyreosis), however, the underlying biochemical mechanism still remains unclear. In this case report we have demonstrated a clear positive correlation between HCG levels and thyroidal hormones in a patient with germ cell tumor suggesting a direct stimulation of hormone producing thyroidal cells by HCG, however, this was not associated with clinical symptoms of hyperthyreosis. Currently, several in vitro studies are underway in our laboratory to further elucidate the biochemical mechanisms of HCG induced hyperthyreosis.

Clonal diversity of Shiga toxin-producing Escherichia coli O157:H7/H- in Germany--a ten-year study

Two hundred and ten E. coli O157:H7/H- strains isolated from single cases and outbreaks of diarrhoea and haemolytic uraemic syndrome (HUS) in Germany between 1988 and 1998 were characterised by a range of molecular subtyping methods and phage typing in order to analyse their clonal nature. A high clonal heterogeneity, together with a considerable clonal stability, has been identified among the bacterial isolates and no single clonal type appeared to be geographically dominant. It is recommended to apply pulsed-field gel electrophoresis (PFGE) together with P gene profile determination (number and genomic positions of lambdoid bacteriophages) as laboratory tools for an extended epidemiological surveillance of E. coli OOFF phage typing will remain helpful as a first line of analysis, particularly in outbreak situations.

Schedule-dependent antagonism of gemcitabine and cisplatin in human anaplastic thyroid cancer cell lines

Anaplastic thyroid carcinoma (ATC) affects primarily elderly patients, with a median survival of 4-12 months after diagnosis. Presently, under clinical investigation the combination of cisplatin (CDDP) and gemcitabine (GEM) has promising activity in several of human tumor types. To develop new approaches for therapy of ATC, we evaluated the antineoplastic activity of GEM and CDDP alone (1-h and 24-h drug exposure) or in combination in the ATC cell lines SW1736, 8505C, C643, and HTh74. IC50 values were determined by the sulforhodamine B assay, activity was evaluated by the relative antitumor activity (RAA) and drug interaction assessed by isobologram analysis. GEM seemed to be active in ATC, with RAA ranging from 12-114 and CDDP only modestly active (RAA, 0.24-1.4). In four different drug schedules tested, the drug combination was additive when GEM preceded CDDP exposure (combination index, approximately 1), whereas when CDDP preceded GEM exposure the combination was significantly antagonistic (combination index, >1). In SW1736 and 8505C cells, we observed a strong S phase arrest and DNA synthesis inhibition 24 h after a 1-h exposure to an IC50 of CDDP. On the basis of molecular drug targets, cell cycle arrest points, and DNA synthesis inhibition, a model was developed to explain the interaction observed for the combination of GEM and CDDP. In conclusion, GEM shows promising cytostatic activity in ATC. Interaction of GEM and CDDP was schedule and dose dependent, favoring a regime in which GEM is followed by CDDP. Additionally, our model system suggests that DNA-synthesis inhibition and S phase arrest may be important determinants for the drug interaction between GEM and CDDP.

Cisplatin resistance and oncogenes--a review

Cisplatin is among the most widely used broadly active cytotoxic anticancer drugs; however, its clinical efficacy is often limited by primary or the development of secondary resistance. Several mechanisms have been implicated in cisplatin resistance, including reduced drug uptake, increased cellular thiol/folate levels and increased DNA repair. More recently, additional pathways have been characterized indicating that altered expression of oncogenes that subsequently limit the formation of cisplatin-DNA adducts and activate anti-apoptotic pathways may also contribute to the resistance phenotype. Several lines of evidence suggest that expression of ras oncogenes can confer resistance to cisplatin by reducing drug uptake and increasing DNA repair; however, this is not a uniform finding. Tumor cells, in contrast to normal cells, respond to cisplatin exposure with transient gene expression to protect or repair their chromosomes. The c-fos/AP-1 complex, a master switch for turning on other genes in response to DNA-damaging agents, has been shown to play a major role in cisplatin resistance. In addition, AP-2 transcription factors, modulated by protein kinase A, are also implicated in cisplatin resistance by regulating genes encoding for DNA polymerase beta and metallothionines. Furthermore, considerable evidence indicates that mutated p53 plays a significant role in the development of cisplatin resistance since several genes implicated in drug resistance and apoptosis (e.g. mismatch repair, bcl-2, high mobility group proteins, DNA polymerases alpha and beta, PCNA, and insulin-like growth factor) are known to be regulated by the p53 oncoprotein. Improved understanding of molecular factors for the development of cisplatin resistance may allow the prediction of clinical response to cisplatin-based treatment. Furthermore, the identification of oncogenes involved in cisplatin resistance has already led to in vitro approaches which successfully inactivated these genes using ribozymes or antisense oligodeoxynucleotides, thus restoring cisplatin sensitivity. It is conceivable that these strategies, once transferred to a clinical setting, may have the potential to enhance the efficacy of cisplatin against a great variety of malignancies and thus more fully exploit the antineoplastic and curative potential of this drug.

Clonal relationship of Salmonella enterica serovar typhimurium phage type DT104 in Germany and Austria

A new epidemic clone of Salmonella enterica serovar Typhimurium designated definitive phage type (DT) 104 has been emerging since 1990 to become most common type among S. Typhimurium isolates in Germany and Austria. Molecular fingerprinting (PFGE-pattern, plasmid profiles, IS200 pattern, ribotype, ERIC-type, OMP and MLE patterns) revealed the majority of the DT104 isolates to have clonal identity; they were designated as type 1 (about 95%). Moreover, clonal type 1 of DT104 was found to occur in sensitive as well as in a range of multiply drug-resistant variants and in a variety of plasmid profile types (in particular with small cryptic plasmids in the range of 1.0 to 5.0 Md). Since the clonal type 1 of DT104 has been identified among isolates from other countries, too, including such from the United Kingdom, the United Arab Emirates, the Philippines, and the Netherlands, its pandemic spread in man indicates that the import/export of this pathogen continues. About 5% of the DT104 isolates have been identified as genetically diverse indicating the independent appearance of the same multiple drug resistance and phage pattern phenotype among different Salmonella ancestor strains.

Preferential repair of the N-ras gene in K 562 cells after exposure to cisplatin

Cisplatin is one of the most active and widely used anticancer drugs; however, its clinical efficiacy is often limited by the development of resistance. Since several studies indicated that ras oncogenes may modulate the cellular response to cisplatin or radiation, we investigated the gene-specific repair of the N-ras gene in the human K 562 cell line after exposure to cisplatin using a novel nonradioactive polymerase chain reaction inhibition assay. This assay is based on the fact that DNA lesions can block the Taq polymerase and thereby result in a decreased amplification of a damaged segment compared to the amplification of the same segment in a non-damaged template. The overall genomic repair rate was measured by atomic absorption spectroscopy. Immediately after cisplatin exposure no amplification segment was observed. However, a complete restoration of the N-ras gene (2.4 kb) was seen after 8 h posttreatment incubation. In contrast, only 60% of the overall genome was repaired at this time. Our results clearly indicate that cisplatin-induced DNA lesions are more efficiently removed from transcribed regions within the DNA, suggesting that the efficiency of DNA repair in a given gene may be correlated to its transcriptional activity. Since ras oncogenes control several cellular signal transduction pathways, known to be involved in DNA damage response, preferential repair of the N-ras gene could therefore be an important step to prevent inactivation of cellular defense mechanisms after exposure to genotoxic agents.

Salmonella typhimurium IroN and FepA proteins mediate uptake of enterobactin but differ in their specificity for other siderophores

Salmonella typhimurium possesses two outer membrane receptor proteins, IroN and FepA, which have been implicated in the uptake of enterobactin. To determine whether both receptors have identical substrate specificities, fepA and iroN mutants and a double mutant were characterized. While both receptors transported enterobactin, the uptake of corynebactin and myxochelin C was selectively mediated by IroN and FepA, respectively.

The role of insulin-like growth factor I and its receptor in cell growth, transformation, apoptosis, and chemoresistance in solid tumors

Insulin-like growth factor I (IGF-I) exerts pleiotropic effects on mammalian cells via stimulation of its receptor (IGF-IR), a receptor tyrosine kinase. In vivo, IGF-I acts both as a local tissue growth factor and as a circulating hormone. In oncological research, IGF-I has received increased attention as the activated IGF-I/IGF-IR system displays mitogeneic, transforming, and anti-apoptotic properties in various cell types by stimulating distinct intracellular signaling pathways. Recent data suggest that the anti-apoptotic effect of IGF-I may mediate decreased sensitivity to chemotherapeutic drugs in vitro and in vivo. Thus, targeting the IGF-I/IGF-IR system could serve as an approach to overcome clinical drug resistance in certain tumors.

Ocular-adnexal lymphoid tumors: a clinicopathologic and molecular genetic study of 77 patients

PURPOSE

To determine whether molecular genetic analysis of ocular-adnexal lymphoid tumors, combined with histopathology and tumor location, is helpful in predicting which patients will develop systemic lymphoma.

METHODS

A combined retrospective and prospective study of 77 patients with ocular-adnexal lymphoid tumors was performed. The tumors were subdivided into conjunctival, orbital, and eyelid lesions, and all were studied using both routine histopathology and molecular genetic analysis.

RESULTS

Most lesions (70%) were small cell lymphomas of the mucosa-associated lymphoid tissue type, and the majority of tumors (90%) contained monoclonal or oligoclonal populations of lymphocytes discovered on molecular genetic analysis. Additionally, 72% of tumors exhibiting clonality had more than one gene rearrangement. Fifty-three percent of patients developed extraocular lymphoma sometime during the course of their disease. Patients with gene rearrangements on Southern blot hybridization had a 52% incidence of nonocular disease, compared with 63% of those without rearrangements. Patients with conjunctival tumors had a 37.5% incidence of nonocular disease, those with orbital tumors had a 54% incidence, and those with eyelid tumors had a 100% incidence of nonocular lymphoma. Only two patients died as result of systemic lymphoma.

CONCLUSIONS

Most ocular-adnexal lymphoid tumors are lymphomas of the mucosa-associated lymphoid tissue type. The majority of tumors exhibit gene rearrangements on molecular genetic analysis, and this technique was not helpful in predicting which patients would develop nonocular lymphoma. Tumor location did have predictive value: Conjunctival lesions had the lowest incidence of nonocular lymphoma, and lid lesions had the highest incidence. Even with disseminated disease, most patients have a favorable prognosis with treatment.

Topoisomerase-I inhibitor SN-38 can induce DNA damage and chromosomal aberrations independent from DNA synthesis

BACKGROUND

SN-38 is the active metabolite of the topoisomerase-I (topo-I) inhibitor Irinotecan (CPT-11). Generally, topo-I inhibitors stabilize the complex between topo-I and DNA which collide with moving DNA replication forks, eventually leading to double stranded DNA damage. Therefore, topo-I inhibitors are regarded as S-phase specific. The present study investigated S-phase dependent and independent effects of SN-38.

MATERIALS AND METHODS

Effects of exposure of A2780 cells to SN-38 (2 hours) were studied by assessing DNA/protein crosslinks, DNA damage and cytogenetic aberrations.

RESULTS

A close correlation (r2 = 0.97) was established between drug-induced DNA/protein crosslinks and double stranded DNA breaks. Cytogenetic analysis revealed near maximum clastogenic effects already evident immediately following 2 hours drug exposure. However, qualitatively, chromatid breaks at 24 hours were different from those at 0 hours, in that at 24 hours they were associated with radial chromosome configurations and sister chromatid exchanges.

CONCLUSION

The data corroborate that the S-phase dependent mechanism of action of topo-I inhibitors is also applicable to SN-38. The cytogenetic data indicate two distinct interactions of SN-38 with DNA: immediate induction of chromatid breaks independent from DNA synthesis, and induction of chromatid breaks associated with radial chromosome configurations dependent on DNA synthesis.

Cellular determinants of resistance to indolocarbazole analogue 6-N-formylamino-12,13-dihydro-1,11-dihydroxy-13(beta-D-glucopyranosyl)- 5H-indolo[2,3-alpha]pyrrolo[3,4-c]carbazole-5,7(6H)-dione (NB-506), a novel potent topoisomerase I inhibitor, in multidrug-resistant human tumor cells

Membrane protein-associated alterations in cellular drug accumulation have been recently implicated in resistance to topoisomerase I (TOP-I)-interactive drugs. The present study investigated the cellular determinants of resistance to the indolocarbazole compound NB-506 [6-N-formylamino-12,13-dihydro-1,11-dihydroxy-13(beta-D-glucopyranosyl)- 5H-indolo[2,3-alpha]pyrrolo[3,4-c]carbazole-5,7(6H)-dione], a structurally novel TOP-I-interactive drug, in parental and multidrug-resistant tumor cells expressing either the P-170 glycoprotein (Pgp170) or multidrug resistance protein (MRP). MRP-expressing 250-fold doxorubicin-resistant human fibrosarcoma HT1080/DR4 tumor cells were drug sensitive to NB-506 and camptothecin (CPT) (resistance factor: 0.7 and 0.8, respectively) with no alterations of TOP-I parameters including DNA relaxation, expression of TOP-I protein and mRNA. In contrast, doxorubicin-resistant human ovarian A2780/Dx5 tumor cells [pgp170 phenotype] were 6.2-fold resistant to NB-506, whereas resistance to CPT was 2.6-fold. HPLC analysis of cellular NB-506 accumulation showed no significant differences between A2780 and A2780/Dx5 cells (peak intracellular concentrations after 120-min exposure to 10 microM NB-506: 400+/-85.0 and 352+/-95.1 nmol NB-506/mg protein, respectively). However, resistant A2780/Dx5 cells expressed a lower amount of TOP-I mRNA and 29% protein levels of TOP-I compared to parental A2780 cells, resulting in decreased TOP-I catalytic activity (3.17+/-0.02 vs. 1.16+/-0.15 rel.U/microg nuclear protein) and reduced induction of NB-506-mediated cleavable complex formation in A2780/Dx5 cells. Furthermore, the lower induction of NB-506-induced protein-linked DNA breaks (PLDB) in A2780/Dx5 cells correlated with significantly decreased DNA 12.2-440 kb size fragmentation in these cells. The present study demonstrates that expression of MRP and Pgp170 does not confer resistance to NB-506. Resistance to indolocarbazole substance NB-506 in A2780/Dx5 cells was only related to downregulation of TOP-I associated with lower induction of cleavable complex formation and DNA fragmentation. The data reported herein may indicate that the new indolocarbazole compound NB-506 has potent antitumor efficacy in membrane-associated multidrug resistance.

Novel cellular determinants for reversal of multidrug resistance in cells expressing P170-glycoprotein

The newly synthesized calcium channel blocker, Ro44-5912, significantly potentiates doxorubicin (Dox)-induced cytotoxicity at non-cytotoxic concentrations in Dox-resistant human ovarian cell line, A2780/DX5, overexpressing P170-glycoprotein (Pgp). Induction of DNA single- and double-strand breaks (ssbs and dsbs) was measured using alkaline elution and constant-field gel electrophoresis (CFGE) assays. The results indicate that potentiation of the cytotoxicity of Dox by Ro44-5912 was accompanied by significant increases in both, Dox-induced DNA ssbs and dsbs in the resistant cells. Pulsed-field gel electrophoresis (PFGE) analysis showed that Dox induced DNA fragments in the 50-800 kilobase (kb) and 0.8-5.7 megabase (Mb) ranges. The majority of the newly synthesized DNA fragments were in the 50-800 kb range. Ro44-5912 treatment resulted in significant potentiation of DNA fragmentation in the 50-800 kb range with a minor increase in 0.8-5.7 Mb DNA fragments, suggesting that the modulator functions by potentiating nascent DNA fragmentation in the resistant cells. Exposure to Dox with Ro44-5912 was associated with a prolonged blockage of cells in the S-phase. In contrast, exposure to Dox alone resulted in temporary blockage of cells in G2/M phase (approximately 24 h) followed by restoration of cell proliferation and normal DNA histograms at 48 h after 2 h drug exposure. Incorporation of BrdUrd by flow cytometric analysis was inhibited by Dox in the presence of Ro44-5912, showing that there is a block of DNA replication. An increased damage in newly synthesized DNA could concur with a blocked DNA replication. Moreover, slowing progression through the S-phase in cells exposed to Dox in combination with Ro44-5912 is accompanied by increased sensitivity of Dox poisons, indicating a correlation of specific S-phase perturbation with the reversal of Dox resistance by Ro44-5912 in cells expressing Pgp. The results suggest that drug-induced augmentation of nascent DNA fragmentation and specific cell-cycle perturbation are potentially important molecular determinants for reversal of multidrug resistance in addition to restoration of intracellular drug retention.

Evaluation of topoisomerase I catalytic activity as determinant of drug response in human cancer cell lines

The prognostic value of topoisomerase I (Topo I) catalytic activity and expression of the multidrug resistance (MDR) marker P-glycoprotein (Pgp) and multidrug resistance protein (MRP) for in vitro sensitivity to Topo I interactive agents were evaluated. The efficacy of short term (2 h) and long term (24 h) exposures of camptothecin (CPT), two CPT derivatives (SN-22, SN-38) and the indolocarbazole compound NB-506, was determined against human ovarian carcinoma (A2780 and A2780 DX5), human fibrosarcoma (HT1080 and IIT1080/DR4) and human ileocecal carcinoma (HCT-8). For each cell line the Topo I protein levels and catalytic activity were determined and correlated with drug-induced cytotoxicity. In general, the Topo I protein levels correlated with Topo I catalytic activity. Drug-induced cytotoxicity increased significantly with prolongation of the exposure time. With the 2 h exposure, the multidrug resistant A2780 DX5 cell line (Pgp+, MRP-) was moderately resistant to all four drugs compared to its parental cell line. In case of CPT and SN-22 but not for SN-38 and NB-506, this resistance was no longer detectable following 24 h drug exposure. No resistance was detectable for the multidrug resistant HT1080/DR4 (Pgp-, MRP+) cell line when compared to its parental cell line. With short term exposures a strong trend was observed toward increased cytotoxicity with increased Topo I catalytic activity, especially if this correlation was studied between derivative cell lines (A2780 vs. A2780 DX5 and HT1080 vs. HT1080/DR4). This correlation weakened when all 5 cell lines and both exposure conditions were considered. Thus, although overall the correlation between Topo I catalytic activity and sensitivity to Topo I interactive drugs between different cell lines is weak, this correlation may be stronger when comparing derivative cell lines. For CPT and SN-22 but not for SN-38 and NB-506, the moderate resistance levels observed in the Pgp-expressing cell line could be negated by prolongation of exposure duration. MRP expression did not effect drug efficacy. The data demonstrate that the importance of Topo I catalytic activity as single prognostic factor for drug response to Topo I interactive agents is weak and that additional mechanisms affecting drug response have to be taken into consideration.

Characterization of urinary Escherichia coli O75 strains

Forty-four Escherichia coli O75 strains from patients with urinary tract infections were characterized by a variety of methods to obtain evidence of their clonal distribution and uropathogenic properties. By K and H antigen typing, the strains were divided into the following serotypes: O75:K5:H- (18 strains), O75:K95:H- (10 strains), O75:K95:H5 (7 strains), O75:K100:H5 (4 strains), and O75:K-:H55 (5 strains). Generally, biotyping proved to be of no discriminative value. With two exceptions the strains were found to be sensitive to the bactericidal effect of normal human serum. As shown by multilocus enzyme electrophoresis, the whole-cell protein profile (WCPP), and the patterns of the outer membrane proteins and lipopolysaccharides, all but the five O75:H55 strains were genetically closely related to each other and could be classified into one clonal group. The O75:K-:H55 strains proved to be quite different and lacked type 1 fimbriae. All 17 K95 (H-, H5) strains produced hemolysin and P fimbriae. Five of the O75:K5:H- strains were different from the other K5 strains by showing hemagglutinating properties, on the basis of the presence of the OX adhesin. The last two groups are suggested to be uropathogenic and are proposed to represent separate clonal groups or subgroups.

p53 and WAF1 are induced and Rb protein is hypophosphorylated during cell growth inhibition by the thymidylate synthase inhibitor ZD1694 (Tomudex)

In a previous study, we found that treatment of HCT-8 cells with ZD1694, a specific antifolate-based thymidylate synthase inhibitor, resulted in DNA fragmentation. In this study, we have demonstrated the dose- and time-dependent induction of DNA fragmentation accompanied by elevation of p53 and WAF1 protein expression by ZD1694. WAF1 mRNA showed a time-dependent increase, whereas p53 mRNA was not found to be significantly overexpressed. The initial increase in WAF1 mRNA was detected at 4 hr, but increased WAF1 protein expression was detected 8-24 hr after a 2-hr exposure. The amount of total and hypophosphorylated pRb seems to be rising greatly after ZD1694 exposure. The effects of ZD1694 on the expression of E2F1 and formation of the E2F1-Rb complex were investigated after a 2-hr drug exposure (IC90). The results showed a time-dependent decrease in E2F1 mRNA and protein expression; an increase in the abundance of the E2F-Rb complex could be demonstrated beginning 4 hr after drug exposure by a gel shift assay. Kinetic analysis showed increased availability of hypophosphorylated pRb for inhibition of E2F, which could indirectly result from WAF1-induced inhibition cyclin-dependent kinase activity. Whereas thymidylate synthase inhibition by ZD1694 was rapid in onset and maintained for at least 24 hr after drug treatment, drug-induced cellular growth inhibition was significant 24 hr after drug exposure. The increased abundance of hypophosphorylated pRb and binding to transcription factor E2F-1 is consistent with ZD1694-induced cell growth inhibition in HCT-8 cells. Therefore, the observed effect on downstream events after effective inhibition of thymidylate synthase may offer the critical determinants of response to ZD1694.

Silibinin protects against cisplatin-induced nephrotoxicity without compromising cisplatin or ifosfamide anti-tumour activity

Cisplatin is one of the most active cytotoxic agents in the treatment of testicular cancer, but its clinical use is associated with side-effects such as ototoxicity, neurotoxicity and nephrotoxicity. Long-term kidney damage from cisplatin particularly affects the proximal tubular apparatus and can be detected by increased urinary excretion of brush-border enzymes, such as L-alanine-aminopeptidase (AAP), and magnesium. In the current study, the flavonoid silibinin was used as a nephroprotectant for cisplatin-induced nephropathy in a rat animal model. Infusion of silibinin before cisplatin results in a significant decrease in glomerular (indicated by creatinine clearance and serum urea level) and tubular kidney toxicity (excretion of brush-border enzymes and magnesium). Silibinin given alone had no effect on renal function. In order to exclude an inhibition of the anti-tumour activity of cisplatin and 4-hydroperoxy-ifosfamide by co-administration of silibinin, in vitro studies were performed in three established human testicular cancer cell lines. Dose-response curves for cisplatin (3-30 000 nmol) combined with non-toxic silibinin doses (7.25 x 10(-6) or 7.25 x 10(-5) mol l-1) did not deviate significantly from those of cisplatin alone as measured by relative cell survival during a 5 day assay using the sulphorhodamine-B staining technique. Also silibinin did not influence the cytotoxic activity of 4-hydroperoxy-ifosfamide (30-10 000 nmol) in vitro. In summary, these in vitro data rule out a significant inhibition of the anti-tumour activity of the major nephrotoxic components, cisplatin and 4-hydroperoxy-ifosfamide, by co-administration of silibinin in a human germ cell tumour cell line model. Together with these demonstrated cytoprotection effects in the rat animal model, these data form the basis for a randomised clinical trial of silibinin for the protection of cisplatin-associated nephrotoxicity in patients with testicular cancer.

Sequence analysis of the DNA binding domain of the estrogen receptor gene in ER (+)/PR (-) breast cancer

Estrogen stimulates the proliferation of breast cancer cells and regulates the expression of other proteins, including the progesterone receptor (PR), via interaction with a unique estrogen receptor (ER), a ligand-inducible transcription factor that binds to regulatory DNA sequences associated with target genes. The best indirect evidence of an intact ER gene signaling system in a tumor is the demonstration of both ER and PR cytosol protein. The molecular basis of the ER (+)/PR (-) phenotype is unknown and may reflect either defective PR gene expression or alterations in the ER-specifically, inability of the ligand-receptor complex to effectively bind to regulatory sequences in DNA. To test the latter possibility, we evaluated 10 ER (+)/PR (-) resected human breast cancers for small deletions and point mutations in the DNA binding domain of the ER gene. Exons 2 and 3 and their flanking intron sequences were selectively amplified using the polymerase chain reaction and then directly sequenced using the Sanger dideoxynucleotide method. A normal gene sequence was found in all cases studied. We conclude that sequence aberrations in the DNA binding domain of the ER are not a common cause of absent PR expression in ER (+)/PR (-) breast carcinomas.

Structural dependence of the allosteric interaction of semi-rigid verapamil analogues with dihydropyridine-binding in kitten heart

Structural determinants of the allosteric interaction of semi-rigid verapamil analogues with dihydropyridine binding were investigated in kitten heart using [3H](+)-isradipine as radioligand. Chemical variations were performed in the alkyl chain of verapamil and include introduction of unsaturation (double or triple bonds) or the insertion of cyclohexyl moieties. Introduction of unsaturation generally reduces the allosteric interaction in the case of 'double bond'-and abolishes it in the case of 'triple bond'-derivatives. Also the introduction of cyclohexyl moieties diminishes the potency of allosteric interaction: derivatives with the phenylethylamino side chain in an equatorial position exhibit the allosteric interaction, while it is lacking in derivatives with the basic side chain in axial position. Thus, the reduced conformational flexibility of the new verapamil congeners reduces or abolishes their ability to allosterically interfere with dihydropyridine binding. A molecular interpretation was approached by molecular modelling studies. The strategy was to find low energy conformations common to the active congeners, but not shared by the inactive ones. Structural features discriminating allosterically active and inactive congeners comprise: 1) the position of the nitrogen, 2) the volume occupied by the N-methyl groups, 3) the direction of the N-H bond and 4) the position of the phenyl ring in the basic side chain.

Genomic and biochemical relatedness between Vibrio cholerae serovar O139 and serovar O1 eltor strains

Vibrio cholerae O139 (Bengal) the new pandemic cholera strain emerging on the Indian subcontinent has revealed considerable homology to Vibrio cholerae O1 EL Tor (strain of the seventh pandemic cholera) in terms of genetic and biochemical properties. Apart from capsule and O139 LPS formation, all strains of V. cholerae O139 were found to be identical to V. cholerae O1 EL Tor strains with respect to genomic restriction fragment length polymorphism, genomic distribution of the pathogenic island, pattern of OMP and multilocus enzymes. However, the analysis of a nonpathogenic V. cholerae O139 isolate from Sri Lanka with a totally different pattern of genetic properties underline that horizontal gene transfer of a piece of DNA encoding biosynthesis of the Vibrio cholerae O139-specific LPS and capsule formation to an O1 El Tor precursor strains must have occurred giving rise to a kind of hybrid V. cholerae O1 El Tor encoding the new serovar-specific O139 antigens.

Application of physico-chemical typing methods for the epidemiological analysis of Salmonella enteritidis strains of phage type 25/17

Eighty-nine Salmonella enteritidis phage type 25/17 strains isolated from a localized outbreak in the German state Nordrhein-Westfalen (outbreak NWI) could not be further differentiated by biochemotyping and plasmid pattern analysis. They were submitted to a complex typing system consisting of modern physico-chemical analytical procedures. In lipopolysaccharide pattern analysis the strains proved to be homogeneous. In multilocus enzyme electrophoresis, outer membrane and whole cell protein pattern (WCPP) analysis, and Fourier-transform infrared (FT-IR) spectroscopy (increasing extent of differentiation in the given order) strains deviating from each basal pattern were found. The extent of correspondence in these deviations was satisfactory. Forty-six strains of the same sero- and phage type, however, obtained from different outbreaks, were additionally typed. The results obtained with them indicate that the data of the first group were not restricted to strains from outbreak NWI, but of general validity. It was found that both WCPP and FT-IR represent valuable methods for the sub-grouping of bacteria.

[The value of urine phosphohexose isomerase activity in comparison with urine cytology. First diagnosis and tumor after-care in patients with cancer of the urinary bladder]

The importance of phosphohexose (PHI) activity in the urine of patients with carcinoma of the urinary bladder is examined on the basis of enzyme-histochemical studies in tumor cell homogenizates after transurethral resection for transitional cell carcinoma. The results gave rise to the question of whether the enzyme-histochemical activity patterns were reflected in the urine in the form of photometrically measurable activity, and thus whether the PHI activity can be used in screening as a marker to complement the standard urine cytological procedure. The sensitivity of PHI measurement was determined at 89%. The measurement of PHI in the urine of patients with an ileum neobladder or of patients with urinary tract infections does not provide any useful information.

Simultaneous expression of CD2 on a B-cell, small lymphocytic neoplasm

An unusual neoplasm, best classified as a B-cell chronic lymphocytic leukemia on the basis of cytofluorographic, immunohistologic, and gene rearrangement analysis also co-expressed the T-cell associated marker CD2 (sheep erythrocyte receptor), but without other cell markers restricted to T cells. This case was associated with a more aggressive course than typically seen with B-CLL or malignant lymphoma, small lymphocytic type, implying along with previous reports that CD2 expression may serve as a marker of small lymphocytic tumor cell behavior and the ultimate clinical course. Thus, surface phenotypic analysis of these particular hematopoietic neoplasms may serve not only for identification of the malignancy, but could also render prognostic information.

[Clonal spreading of a multidrug resistance Citrobacter freundii strain at a neonatal intensive care unit]

This paper reports on the epidemic spreading of a multiresistant Citrobacter (C.) freundii strain at a neonatal intensive care unit. A premature baby of the 27th week of pregnancy died from septic shock caused by this strain. According to the result of a statistical analysis of risk factors a connection between the colonization of neonates and the feeding with an enteral feeding tube was probably. This suspicion could be confirmed by the detection of the multiresistant strain in the infant formula. Plasmid analysis, examination of outer membrane proteins and lipopolysaccharides of these C. freundii strains demonstrated the identity of all isolates. The resistance to antibiotics of this multiresistant C. freundii clone was determined by a plasmid belonging to incompatibility group C with a molecular weight of 110 MDa. This plasmid was involved also in other nosocomial outbreaks. It persisted more than 7 years in the hospital flora of the intensive care unit.

Nourseothricin (streptothricin) inactivated by a plasmid pIE636 encoded acetyl transferase of Escherichia coli: location of the acetyl group

Escherichia coli strains harbouring the plasmid pIE636 are able to synthesize acetylcoenzyme A: streptothricin acetyltransferase (ACSAT). The (enzymatic) N-acetylation of streptothricin F is known to contribute significantly towards the loss of antibacterial activity. 13C-NMR analysis of [14C]N-acetyl-labelled streptothricin F, produced by ACSAT-catalysed acetylation of streptothricin F and subsequent purification by various chromatographical steps, unequivocally revealed streptothricin F to be acetylated at the beta-amino group (C16) (and not at the epsilon-amino group (C19)).

Verapamil analogues with restricted molecular flexibility: synthesis and pharmacological evaluation of the four isomers of alpha-[1-[3-[N-[1- [2-(3,4-dimethoxyphenyl)ethyl]]-N-methylamino]cyclohexyl]]-alpha- isopropyl-3,4-dimethoxybenzene-acetonitrile

The synthesis and pharmacological activities of the four isomeric racemates of alpha-[1-[3-[N-[1-[2-(3,4-dimethoxyphenyl)ethyl]]-N- methylamino]cyclohexyl]]-alpha-isopropyl-3,4-dimethoxybenzene-acetoni trile are reported (2a-d). The compounds are verapamil analogues with restricted molecular flexibility designed to gather information on the active conformation(s) of the parent drug. The relative stereochemistry of the four racemates was established by X-ray crystallography and by 1H NMR spectroscopy; conformational analysis was supported by theoretical calculations. Negative inotropic and chronotropic activities were evaluated on guinea pig atria, while vasodilatory activity on smooth muscle was tested on guinea pig aortic strips. Binding studies on cat ventricles were performed using (-)-[N-methyl-3H]desmethoxyverapamil (D888) as a reference ligand. The results seem to support the hypothesis that cardiac depressant and vasorelaxant activities are due to different conformations of the verapamil molecule.

Determination of hormonal response in uterine cancer cell lines by the ATP bioluminescence assay and flow cytometry

Although progesterone receptor status has been shown to correlate with response to hormonal therapy, not all progesterone receptor-positive patients respond to this treatment and additional biologic assays are needed to help better predict clinical response to hormonal therapy. This study explored the potential of the ATP bioluminescence assay and flow cytometry as biological assays of hormonal response. Five uterine cancer cell lines were used: AE7, ECC-1, HEC1A, AN3, and SKUT1B. Cells were exposed to Provera or tamoxifen at 0.1, 0.2, 0.5, 1, 2, and 5X (X equal to peak plasma concentrations: 1.0 micrograms/ml Provera and 0.1 micrograms/ml tamoxifen). For correlation, estrogen and progesterone receptors were determined by the standard dextran-coated charcoal method. Only AE7 and ECC-1 were positive for progesterone receptors (501 fmol/mg AE7, 194 fmol/mg ECC-1) and the rest were negative (less than 8 fmol/mg). Tamoxifen exerted no inhibition to the above cell lines. Meanwhile, Provera exerted dose-response inhibition on both AE7 and ECC-1 cell lines. The effects of accumulation of G0-G1 phase and reduction of S, G2 cells (P less than 0.05), but not on the HEC1A cell line (P = 0.4). These changes confirmed the antiproliferative property of Provera. Further studies are needed to establish the role of the ATP bioluminescence assay and flow cytometry as biological assays of hormonal response.