Conformational analyses of 2,3-dihydroxypropanoic acid as a function of solvent and ionization state as determined by NMR spectroscopy

Vicinal (1)H--(1)H coupling constants were used to determine the conformational preferences of 2,3-dihydroxypropanoic acid (1) (DL-glyceric acid) in various solvents and its different carboxyl ionization states. The stereospecific assignments of J(12) and J(13) were confirmed through the point-group substitution of the C-3 hydrogen with deuterium, yielding rac-(2SR,3RS)-[3-(2)H]-1, and the observation of only J(13) in the (1)H NMR spectra. While hydrogen bonding and steric strain may be expected to drive the conformational equilibrium, their role is overshadowed by a profound gauche effect between the vicinal hydroxyl groups that mimics other substituted ethanes, such as 1,2-ethanediol and 1,2-difluoroethane. At low pH, the conformational equilibrium is heavily weighted toward the gauche-hydroxyl rotamers with a range of 81% in DMSO-d(6) to 92% in tert-butyl alcohol-d(10). At high pH, the equilibrium exhibits a larger dependence upon the polarity and solvating capability of the medium, although the gauche effect still dominates in D(2)O, 1,4-dioxane-d(8), methanol-d(4), and ethanol-d(6) (96, 89, 85, and 83% gauche-hydroxyls respectively). The observed preference for the gauche-hydroxyl rotamers is believed to stem primarily from hyperconjugative sigma(C--H) --> sigma*(C--OH) interactions.

Gender Differences in Pain and Healthcare Utilization for Adult Sickle Cell Patients: The PiSCES Project

BACKGROUND

Many studies have found gender differences in frequency and intensity of pain. Women often report lower pain thresholds, higher pain ratings, and lower tolerance for pain. People with sickle cell disease (SCD) experience both chronic and acute pain throughout life.

OBJECTIVES

To compare adult men and women with SCD in terms of reported pain, crises, healthcare utilization, and opioid usage.

METHODS

Two hundred twenty-six adults with SCD in Virginia were enrolled in a prospective cohort study of pain and completed daily diaries for 1-6 months. Subjects reported for the previous day their maximum SCD-related pain, distress, and interference (0-9 scale), whether they were in a sickle cell crisis, had unplanned utilization (clinic, emergency room, or hospitalization), or used opioids. Episodes of pain, crisis, or utilization were defined as consecutive days of such. Men and women were compared, using analysis of covariance (ANCOVA), controlling for age, SCD genotype, depression, and education.

RESULTS

There were no significant differences between men and women in the percentage of days subjects experienced pain (men 58.6% vs. women 56.5%) or the number of pain episodes/6 months (7.7 vs. 9.6). Mean pain scores were comparable, when subjects were in crisis (5.5 vs. 5.6) or not (2.5 vs. 2.2). Distress and interference results were similar. Men with the SS genotype reported a higher percentage of days with crisis(18.5% vs. 11.6%) and utilization (5.1% vs. 2.7%) than women with the SS genotype.

CONCLUSIONS

Contrary to many studies of pain, particularly chronic pain, men and women with SCD reported generally similar pain experiences.

Synergistic affective analgesic interaction between delta-9-tetrahydrocannabinol and morphine

Evidence for an analgesic interaction between delta-9-tetrahydrocannabinol (Delta(9)-THC) and morphine was sought using an experimental pain model applied to normal volunteers. The study incorporated a double blinded, four treatment, four period, four sequence, crossover design. Subjects received Delta(9)-THC 5 mg orally or placebo and 90 min later morphine 0.02 mg/kg intravenously or placebo. Fifteen minutes later subjects rated the pain associated with the application of thermal stimuli to skin using two visual analog scales, one for the sensory and one for the affective aspects of pain. Among sensory responses, neither morphine nor Delta(9)-THC had a significant effect at the doses used, and there was no significant interaction between the two. Among affective responses, although neither morphine nor Delta(9)-THC had a significant effect, there was a positive analgesic interaction between the two (p = 0.012), indicating that the combination had a synergistic affective analgesic effect. The surprisingly limited reported experimental experience in humans does not support a role for Delta(9)-THC as an analgesic or as an adjunct to cannabinoid analgesia, except for our finding of synergy limited to the affective component of pain. Comparison of our results with those of others suggests that extrapolation from experimental pain models to the clinic is not likely to be a straight-forward process. Future studies of Delta(9)-THC or other cannabinoids in combination with opiates should focus upon clinical rather than experimental pain.

Phase 2 Study of the g209-2M Melanoma Peptide Vaccine and Low-Dose Interleukin-2 in Advanced Melanoma

High-dose interleukin-2 (IL-2) is the only approved immunologic therapy for advanced melanoma, but response rates are low and significant toxicities limit treatment to otherwise healthy patients. g209-2M is a nanopeptide engineered to mimic an epitope of the gp100 melanocyte differentiation protein that is recognized in a human leukocyte antigen (HLA)-restricted manner by melanoma tumor-infiltrating lymphocytes in some patients. Previous reports indicated that administration of the g209-2M peptide could induce g209-reactive circulating T cells in patients with melanoma and that the combination of g209-2M and high-dose IL-2 might be a more active treatment than high-dose IL-2 alone. Low-dose IL-2 is not active but has significant biologic effects, and because of a different toxicity profile, it can be offered to most patients. The primary objective of this cooperative group phase 2 study was to determine the activity of the combination of g209-2M and low-dose IL-2 in advanced melanoma. Twenty-six HLA appropriate patients with advanced melanoma received subcutaneous g209-2M peptide once every 3 weeks and subcutaneous IL-2 (5 million IU/m) daily for 5 days during the first and second weeks. Patients were monitored for tumor response, toxicity, and induction of g209-reactive circulating T cells. There were no objective responses. There were no toxic deaths and no grade 4 toxicities. More than half of the patients experienced some grade 2 toxicity and one quarter experienced grade 3 toxicity. There was no convincing evidence by enzyme-linked immunospot or tetramer analysis of induction of g209-reactive circulating T cells. The combination of g209-2M and low-dose IL-2 is safe and tolerable but inactive against advanced melanoma. Absence of evidence of immunization raises concerns for peptide-based immunization strategies with concurrent IL-2.

Intramolecular Hydrogen Bonding in Disubstituted Ethanes. A Comparison of NH···O- and OH···O- Hydrogen Bonding through Conformational Analysis of 4-Amino-4-oxobutanoate (succinamate) and Monohydrogen 1,4-Butanoate (monohydrogen succinate) Anions

Relative strengths of amide NH...O- and carboxyl OH...O- hydrogen bonds were investigated via conformational analysis of succinamate and monohydrogen succinate anions with the aid of vicinal proton-proton NMR couplings and B3LYP DFT quantum mechanical calculations for a variety of solvents. New experimental results for succinamate are compared with those obtained from previous studies of monohydrogen succinate. While some computational results for monohydrogen succinate were published previously, the results contained herein are the product of a more powerful methodology than that used earlier. The experimental results clearly show that intramolecular hydrogen-bond formation is more favored in aprotic solvents than in protic solvents for both molecules. Furthermore, the preference of the succinate monoanion for the gauche conformation is much stronger in aprotic solvents than that of succinamate, indicating that the OH...O- hydrogen bond is substantially stronger than its NH...O- counterpart, despite the approximately 5 kcal cost for formation of the E configuration of the carboxyl group needed to make an intramolecular hydrogen bond. The actual energy differences between formation of internal hydrogen bonds for monohydrogen succinate and succinamate anion were estimated by comparison of the relative values of K1 of the respective acids in water and DMSO by a procedure first developed by Westheimer. Recent theoretical work with succinamate highlights the necessity of considering substituent orientational degrees of freedom to understand the conformational equilibria of the central CH2-CH2 torsions in disubstituted ethanes. Similar methodology is applied here to succinic acid monoanion, by mapping potential-energy surfaces with respect to the CH2-CH2 torsional, carboxyl-substituent rotational, and carboxyl-proton E/Z isomeric degrees of freedom. Boltzmann populations were compared with gauche populations estimated from the experimentally determined coupling constants. The quantum mechanical results for succinamate show a much weaker tendency toward hydrogen bonding than for the succinic acid monoanion. However, the theoretical methods employed appear to substantially overestimate contributions from intramolecularly hydrogen-bonded structures for the succinic acid monoanion when compared with experimental results. Natural bond orbital analysis, applied to the quantum mechanical wave functions of fully optimized gauche and trans structures, showed a strong correlation between the population of amide sigma*(N-H) and carboxyl sigma*(O-H) antibonding orbitals and apparent hydrogen-bonding behavior.

Pople, Schneider, and Bernstein — A truly seminal treatise of NMR

The appearance of the authoritative and comprehensive book, High-Resolution Nuclear Resonance Spectroscopy, by John A. Pople, William G. Schneider, and Harold J. Bernstein in 1959 came at just the right time for chemists and other scientists to develop a clear vision of the wide breadth of applications of this critical emerging field and, in addition, to have the opportunity to learn the underlying basic theory in substantial detail.Key words: Pople, Schneider, Bernstein, NMR theory, NMR applications.

15(S)-Lipoxygenase-2 Mediates Arachidonic Acid-stimulated Adhesion of Human Breast Carcinoma Cells through the Activation of TAK1, MKK6, and p38 MAPK

The dietary cis-polyunsaturated fatty acid, arachidonic acid, stimulates adhesion of metastatic human breast carcinoma cells (MDA-MB-435) to the extracellular matrix, but the molecular mechanisms by which fatty acids modify the behavior of these cells are unclear. Exposure to arachidonic acid activates multiple signaling pathways. Activation of p38 mitogen-activated protein kinase (p38 MAPK) is required for increased cell adhesion to type IV collagen, and this activation is sensitive to inhibitors of lipoxygenases, suggesting a requirement for arachidonic acid metabolism. The goals of the current study were to identify the one or more key metabolites of arachidonic acid that are responsible for activation of p38 MAPK and to elucidate the upstream kinases that lead to p38 MAPK activation. High performance liquid chromatographic analysis revealed that MDA-MB-435 cells metabolize exogenous arachidonic acid predominantly to 15(S)-hydroxyeicosatetraenoic acid (15(S)-HETE). Immunoblot analysis with antibodies specific to 15(S)-lipoxygenase-1 (LOX-1) and 15(S)-lipoxygenase-2 (LOX-2) demonstrated the expression of 15-LOX-2, but not 15-LOX-1, in these tumor cells. A LOX inhibitor, nordihydroguaiaretic acid, attenuated production of 15(S)-HETE and inhibited the phosphorylation of p38 MAPK following exposure to arachidonic acid. In contrast, overexpression of LOX-2 sensitized the cells to the addition of arachidonic acid, leading to increased activation of p38 MAPK. Addition of exogenous 15(S)-HETE to MDA-MB-435 cells stimulated cell adhesion to type IV collagen and activated the p38 MAPK pathway, including the upstream kinases transforming growth factor-beta1-activated protein kinase-1 (TAK1) and MAPK kinase 6. Transfection of these cells with a dominant negative form of TAK1 blocked arachidonic acid-stimulated p38 MAPK phosphorylation. These data demonstrate that 15(S)-LOX-2 generation of 15(S)-HETE activates specific growth factor receptor-related signaling pathways, thereby initiating signal transduction events leading to increased cell adhesion to the extracellular matrix.

Health related quality of life in sickle cell patients: the PiSCES project

Background

Sickle cell disease (SCD) is a chronic disease associated with high degrees of morbidity and increased mortality. Health-related quality of life (HRQOL) among adults with sickle cell disease has not been widely reported.

Methods

We administered the Medical Outcomes Study 36-item Short-Form to 308 patients in the Pain in Sickle Cell Epidemiology Study (PiSCES) to assess HRQOL. Scales included physical function, physical and emotional role function, bodily pain, vitality, social function, mental health, and general health. We compared scores with national norms using t-tests, and with three chronic disease cohorts: asthma, cystic fibrosis and hemodialysis patients using analysis of variance and Dunnett's test for comparison with a control. We also assessed whether SCD specific variables (genotype, pain, crisis and utilization) were independently predictive of SF-36 subscales, controlling for socio-demographic variables using regression.

Results

Patients with SCD scored significantly worse than national norms on all subscales except mental health. Patients with SCD had lower HRQOL than cystic fibrosis patients except for mental health. Scores were similar for physical function, role function and mental health as compared to asthma patients, but worse for bodily pain, vitality, social function and general health subscales. Compared to dialysis patients, sickle cell disease patients scored similarly on physical role and emotional role function, social functioning and mental health, worse on bodily pain, general health and vitality and better on physical functioning. Surprisingly, genotype did not influence HRQOL except for vitality. However, scores significantly decreased as pain levels increased.

Conclusion

SCD patients experience health related quality of life worse than the general population, and in general, their scores were most similar to patients undergoing hemodialysis. Practitioners should regard their HRQOL as severely compromised. Interventions in SCD should consider improvements in health related quality of life as important outcomes.

'Objective' determination of coupling constants and conformational equilibria by solvent variation: a re-evaluation

An 'objective' method for determining conformational equilibria in substituted ethanes, proposed by Abraham et al., has been evaluated by computational methods. Abraham's method involves measuring vicinal couplings, such as (3)J(H,H) and (3)J(H,F), between methine and methylene protons with methine, methylene protons and fluorine in a range of solvents, on the assumption that the underlying coupling constants of the individual conformers are constant, but the fractions of each conformer in each solvent are different and unknown. Abraham posited that this would produce an 'over-determined' data set with more equations than unknowns would. Abraham's procedure is re-evaluated, and it is demonstrated that the type of system being considered here, where there are more equations than unknowns, is not necessarily over-determined. A computer equation solver and Monte Carlo-type procedures were employed to demonstrate that multiple numerical solutions exist for a representative 'over-determined' data set provided by Abraham. A statistical method was also developed to determine precisely which parameter sets constitute plausible solutions.

An NMR investigation of the importance of intramolecular hydrogen bonding in determining the conformational equilibrium of ethylene glycol in solution

Although conformational analysis by NMR of ethylene glycol indicates generally strong preferences for the gauche conformation in solvents ranging from water to chloroform, the bulk of the NMR evidence indicates that intramolecular hydrogen bonding between the hydroxyl groups is unlikely to be a significant factor in determining that preference, except possibly in fairly non-polar solvents. The 'gauche effect' is clearly very important, especially in aqueous solution.

Use of an implantable drug delivery system for refractory chronic sickle cell pain

An increasing number of chronic sickle cell patients are being treated with sustained-release opioids in the same manner as cancer patients. In a randomized clinical trial of patients with refractory cancer pain, implantable intrathecal drug delivery systems (IDDS) improved clinical success compared to comprehensive medical management alone. We implanted IDDS pumps in two sickle cell patients with refractory bone pain. Both patients achieved rapid and sustained relief of pain, with dramatic reduction in the use of as-needed opioids, crises, and admissions. IDDS may offer relief for sickle cell patients with refractory pain. A prospective trial with more participants is planned.

Understanding pain and improving management of sickle cell disease: the PiSCES study

Until recent decades, sickle cell disease (SCD) was associated with recurrent, disabling pain, organ failure and death in childhood or early adulthood. SCD treatment advances have now decreased pain and prolonged survival, but episodic or chronic pain may still require substantial analgesic use and frequent hospitalization for pain episodes. This pain is poorly characterized and often poorly treated. Adult patients may face barriers to comprehensive SCD care, stigmatization of their care-seeking behavior by providers and lack of family support, forcing them into maladaptive coping strategies. The Pain in Sickle Cell Epidemiology Study (PiSCES) attempts to develop and validate a biopsychosocial model of SCD pain, pain response and healthcare utilization in a large, multisite adult cohort. PiSCES participants complete a baseline survey and six months of daily pain diaries in which they record levels of SCD-related pain and related disability and distress as well as responses to pain (e.g., medication use, hospital visits). PiSCES will advance methods of measuring pain and pain response in SCD by better describing home-managed as well as provider-managed pain. PiSCES will assess the relative contributions of biological (disease-related), psychosocial and environmental (readiness to utilize) factors to overall pain and pain response in SCD, suggesting targets for biobehavioral interventions over time. Importantly, PiSCES will also identify "triggers" of SCD pain episodes and healthcare utilization in the moment of pain, suggesting targets for timely care that mutes pain episodes.

Comparative Analysis of Passive Dosimetry and Biomonitoring for Assessing Chlorpyrifos Exposure in Pesticide Workers

Under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), the US Environmental Protection Agency (EPA) has the authority to regulate the use of pesticides to prevent unreasonable adverse human health effects associated with pesticide exposure. Accordingly, the EPA requires pesticide registrants to perform studies evaluating the potential for pesticide handler exposure. Data from five such studies that included exposure measurements based on both external measurements and biological monitoring were used to examine methods of assessment, routes and determinants of exposure and dose to the pesticide chlorpyrifos. Eighty workers across four job classes were included: mixer/loaders (M/L, n = 24), mixer/loader/applicators (M/L/A, n = 37), applicators (A, n = 9) and re-entry scouts (RS, n = 10). Results showed that doses were highly variable and differed by job class (P < 0.05) with median total (inhalation and dermal combined) exposure-derived absorbed doses (EDADtot) of 129, 88, 85 and 45 microg/application for A, M/L/A, M/L and RS, respectively. Doses derived from the measurement of 3,5,6-trichloro- 2-pyridinol (3,5,6-TCP) in urine were similar in magnitude but differed in rank with median values of 275, 189, 122 and 97 microg/application for A, M/L, RS, and M/L/A, respectively. The relative contribution of dermal to inhalation exposure was examined by their ratio. The median ratios of exposure-derived absorbed dermal dose (EDADderm) (assuming 3% absorption) to exposure-derived absorbed inhalation dose (EDADinh) (assuming 100% absorption) across job classes were 1.7, 1.5, 0.44 and 0.18 for RS, M/L, A and M/L/A, respectively, with an overall median of 0.6. For 34 of 77 workers (44%), this ratio exceeded 1.0, indicating the significance of the dermal exposure pathway. Different dermal absorption factor (DAF) assumptions were examined by comparing EDADtot to the biomarker-derived absorbed dose (BDAD) as a ratio where EDADtot was calculated assuming a DAF of 1, 3 and 10%. Median ratios of 0.45, 0.71 and 1.28, respectively, were determined suggesting the DAF is within the range of 3-10%. A simple linear regression of urinary 3,5,6-TCP against EDADtot indicates a positive association explaining 29% of the variability in the 3,5,6-TCP derived estimate of dose. A multiple linear regression model including the variables EDADderm, EDADinh and application type explained 46% of the variability (R2 = 0.46) in the urinary dose estimate. EDADderm was marginally significant (P = 0.066) while EDADinh was not (P = 0.57). The EDADderm regression coefficient (0.0007) exceeded the coefficient for EDADinh (0.00002) by a factor of 35. This study demonstrates the value of the pesticide registrant database for the purpose of evaluating pesticide worker exposure. It highlights the significance of the dermal exposure pathway, and identifies the need for methods and research to close the gap between external and internal exposure measures.

Phase I studies of weekly administration of cytotoxic agents: implications of a mathematical model

Certain toxic effects of cytotoxic anticancer agents typically evolve over weeks. When such agents are administered weekly, these effects are cumulative. With such schedules, good medical practice mandates dose modifications with mild or moderate toxicity in order to avoid progression to serious or life-threatening toxicity. These modifications lead to differences between scheduled and delivered doses. Phase I studies are designed to identify the maximum tolerated dose for a given schedule. Yet neither standard phase I study designs nor the theoretical literature acknowledge the existence or incorporate the impact of dose modifications upon phase I study outcomes. Our purpose was to better understand the impact of dose reductions/omissions upon outcomes of phase I studies of weekly administration of cytotoxic agents. We created a mathematical model in which toxicity was represented as a power function of dose in order to represent extremes of behavior observed with actual cytotoxic agents in the clinic. We used the model to simulate dosing and toxicity experiences across a wide range of doses. From these simulations we identified "best doses" according to a variety of traditional and novel criteria. We find the concept of maximum tolerated dose inadequate for the determination of best doses. We also suggest a strategy for a new phase I study design which can be used to estimate the "best dose" corresponding to a specified delivery rate. In summary, identification of best doses requires attention, not only to dose limiting toxic events, but also to delivered dose rates and schedule adherence.

Senior student nurses information seeking skills: a comparative study

Information seeking is one of the key skills in the problem-solving process. This paper explores and compares the information seeking skills of senior student nurses (n = 253) from three pre-registration nurse education programmes: Registered General Nurse (RGN); diploma Registered Nurse (Diploma RN); and integrated degree. Skills were explored using a paper and pencil simulation exercise. Study findings revealed both similarities and differences between the groups. Few students displayed a holistic approach when acquiring information and the rationale for information requests was cited infrequently. The integrated degree programme participants displayed a more systematic approach to information acquisition, while more RGN programme participants referred to the use of a model. The most favoured model to aid data acquisition was Roper et al.'s [The Elements of Nursing, third ed., Churchill Livingstone, Edinburgh, 1996] Activities of Living Model. The study findings are discussed in the wider context of professional education and practice and the potential for further development of information seeking skills on pre-registration nurse education programmes is noted.

Requirement of protein kinase C micro activation and calpain-mediated proteolysis for arachidonic acid-stimulated adhesion of MDA-MB-435 human mammary carcinoma cells to collagen type IV

Arachidonic acid (AA) stimulation of adhesion of human metastatic breast carcinoma cells to collagen type IV depends on the protein kinase C (PKC) pathway(s) and is associated with the translocation of PKC mu from the cytoplasm to the membrane. In the present study, we have further explored the role of PKC mu in AA-stimulated adhesion. PKC mu activation site serines 738/742 and autophosphorylation site serine 910 are rapidly phosphorylated, and in vitro PKC mu kinase activity is enhanced in response to AA treatment. Inhibition of PKC mu activation blocks AA-stimulated adhesion. A phosphorylated, truncated species of PKC mu was detected in AA-treated cells. This 77-kDa protein contains the kinase domain but lacks a significant portion of the regulatory domains. Inhibition of calpain protease activity blocks generation of the truncated protein, promotes accumulation of the activated, full-length protein in the membrane, and blocks the AA-mediated increase in adhesion. p38 MAPK activity is also required for AA-stimulated adhesion. Activation of PKC mu and p38 are independent events. However, inhibition of p38 activity reduces calpain-mediated proteolysis of PKC mu and in vivo calpain activity, suggesting a role for p38 in regulation of calpain activity and a point for cross-talk between the PKC and MAPK pathways. These results support the hypothesis that AA stimulates activation of PKC mu, which is cleaved by calpain at the cell membrane. The resulting truncated kinase, as well as the full-length kinase, may be required for increased cell adhesion to collagen type IV. Additionally, these studies present the first evidence for calpain cleavage of a non-structural protein leading to the promotion of tumor cell adhesion.

RTOG 97-06: Initial report of a Phase I–II trial of selective bladder conservation using TURBT, twice-daily accelerated irradiation sensitized with cisplatin, and adjuvant MCV combination chemotherapy

To examine combination cisplatin and twice-daily accelerated irradiation (RT) after aggressive transurethral resection of bladder tumor (TURBT) in an attempt to preserve the bladder and to determine the likelihood that patients who complete this regimen could then complete three cycles of methotrexate, cisplatin, vinblastine (MCV) chemotherapy. Between 1998 and 2000, 52 patients with Stage T2-T4aN0M0 disease, from 17 institutions, were entered into the trial. Forty-seven patients were deemed eligible; the planned accrual was 40. Of the 46 patients, 68% were >60 years old, 70% were men, and 96% had a Karnofsky score >/=90. The clinical T stage was T2 in 66%, T3a in 25%, and T3b in 9%. The median follow-up at the time of analysis was 26 months. The protocol required TURBT within 6 weeks of the initiation of induction therapy. Induction treatment involved 13 days of concomitant boost RT, 1.8 Gy to the pelvis in the morning followed by 1.6 Gy to the tumor 4-6 h later. For sensitization, cisplatin (20 mg/m(2)) was given on the first 3 days of each treatment week. Three to four weeks after induction, patients were evaluated cystoscopically for residual disease. Patients whose biopsies and cytologic evaluations showed no disease completed consolidation chemoirradiation. Patients with residual tumor went on to cystectomy. After either consolidation or cystectomy, patients were to complete three cycles of MCV chemotherapy. Of the 47 patients, 45% completed all phases of the protocol treatment with minor, or no, deviations. Five patients refused either the postinduction evaluation or cystectomy and 6 refused adjuvant chemotherapy. The CR rate after induction therapy was 74%. For 2 patients, residual disease after induction was limited to positive cytologic findings, and for 8 patients, biopsy of the primary site revealed persistence. Of the 8 cystectomy patients, 2 had no evidence of disease in the bladder at pathologic review of the surgery specimen. Grade 3 toxicity related to chemotherapy was observed in 11% of patients during both induction and consolidation, and in 41% during adjuvant chemotherapy. A total of 8 patients (36% of those receiving adjuvant chemotherapy) went on to develop Grade 4 neutropenia or thrombocytopenia during additional adjuvant chemotherapy. Grade 3 toxicity due to RT was seen in 4% and 0% of patients during induction and consolidation, respectively. One patient developed Grade 4 hydronephrosis during consolidation. The projected 36-month value for locoregional failure, distant metastasis, overall survival, and bladder-intact survival was 27%, 29%, 61%, and 48%, respectively. After aggressive TURBT, twice-daily accelerated RT initiated in concomitant-boost format is well tolerated and results in a rate of complete response (74%) similar to that in previous bladder-sparing trials. The projected 2-year values for locoregional control, bladder-intact survival, and overall survival were also consistent with previously reported trials of bladder-sparing treatment. With only 45% of patients completing three cycles of MCV, this form of adjuvant chemotherapy appears to be poorly tolerated by most patients.

Conformations of 2-Carboxy-1,4-butanedioic Acid as a Function of Ionization State in Dimethyl Sulfoxide

[reaction: see text] The conformational equilibria of 2-carboxy-1,4-butanedioic acid and its mono-, di-, and trianions were estimated by NMR couplings in dimethyl sulfoxide (DMSO). Intramolecular hydrogen bonding was inferred for the mono- and dianions, but not for the triacid. For the di- and trianions, the (3)J(HH) couplings were consistent with the negative carboxylate groups being much closer together than might be expected from electrostatic repulsion considerations. The successive triacid pK(a) values were estimated as 7.0, 13.4, and approximately 20(?) on the Bordwell scale.

The use of cyclin-dependent kinase inhibitors alone or in combination with established cytotoxic drugs in cancer chemotherapy

Cyclin-dependent kinase (CDK) inhibitors are small molecule inhibitors of the kinases required for the orderly progression of cells, both normal and neoplastic, through the cell cycle. Because cell cycle dysregulation is such a common occurrence in neoplasia, the search for agents that might block cell cycle traverse has been the focus of intense interest. These efforts have led to the identification of a broad array of compounds that interfere directly with the function of CDKs. Two of these agents (flavopiridol and UCN-01) have now entered the clinical arena, and others are scheduled to do so in the near future. In preclinical studies, CDK inhibitors have shown the ability not only to block neoplastic cell proliferation, but also to induce, through a variety of mechanisms, programmed cell death. The latter capacity may stem from the diverse effects that CDK inhibitors exert on multiple kinases and apoptotic regulatory molecules. In addition, there is abundant preclinical evidence that CDK inhibitors can potentiate, generally in a dose- and sequence-dependent manner, the anti-tumor effects of many established cytotoxic agents. In clinical studies in humans, flavopiridol and UCN-01 have been shown to be tolerable, although clear evidence of single agent activity or enhancement of the efficacy of established agents has not yet emerged. This may reflect a failure to optimize drug schedules/pharmacokinetics, or to identify the critical molecular targets of these agents. Finally, in recent years, a rationale has emerged for combining CDK inhibitors with other molecularly targeted agents (i.e. differentiation-inducers and signal transduction modulators). Current research has basically two goals: (a). to identify CDK inhibitor concentrations and schedules that inhibit the growth of and induce apoptosis in specific tumor cell types; and (b). to establish a rational basis for combining CDK inhibitors with more conventional cytotoxic agents to enhance antitumor efficacy. This review gives a brief summary of such efforts, with an emphasis on agents and combinations that are in or near clinical development.

Quantum-mechanical calculations of the stabilities of fluxional isomers of C4H(7)(+) in solution

Although numerous quantum calculations have been made over the years of the stabilities of the fluxional isomers of C(4)H(7)(+), none have been reported for other than the gas phase (which is unrealistic for these ionic species) that exhibit exceptional fluxional properties in solution. To be sure, quantum-mechanical calculations for solutions are subject to substantial uncertainties, but nonetheless it is important to see whether the trends seen for the gas-phase C(4)H(7)(+) species are also found in calculations for polar solutions. Of the C(4)H(7)(+) species, commonly designated bisected-cyclopropylcarbinyl 1, unsym-bicyclobutonium 2, sym-bicyclobutonium 3, allylcarbinyl 4, and pyramidal structure 6, the most advanced gas-phase calculations available thus far suggest that the order of stability is 1 > or = 2 > or = 3 4 6 with barriers of only approximately 1 kcalmol for interconversions among 1, 2, and 3. We report here that, when account is taken of solvation, 2 turns out to be slightly more stable than 1 or 3 in polar solvents. The pattern of the overall results is unexpected, in that despite substantial differences in structures and charge distributions between the primary players in the C(4)H(7)(+) equilibria and the large differences in solvation energies calculated for the solvents considered, the differential solvent effects from species to species are rather small.

Effect of tamoxifen on venous thrombosis risk factors in women without cancer: the Breast Cancer Prevention Trial

Tamoxifen reduces breast cancer incidence among healthy women, but is associated with an increased risk of venous thrombosis. We studied the 6 month effects of tamoxifen on venous thrombosis risk factors in women without cancer. One hundred and eleven women at one centre who were participants in a multicentre breast cancer prevention trial were randomized, in double-blind fashion, to receive 20 mg/d of tamoxifen or placebo. The activated protein C (APC) ratio and concentrations of antithrombin, protein C antigen, and total protein S were measured at baseline and 6 months of treatment. None of the factors changed over 6 months in placebo-treated women. Among tamoxifen-treated women, antithrombin and protein S, but not protein C or APC ratio were reduced. Sequential antithrombin concentrations with tamoxifen were 114% and 104% (P = 0.001 compared with placebo). Sequential protein S concentrations with tamoxifen were 18.42 and 17.30 micro g/ml (P = 0.02 compared with placebo). Reductions in antithrombin and protein S were greater in postmenopausal women, but did not differ by other risk factors for venous thrombosis, such as body mass index. Reductions of antithrombin and protein S, but not protein C or APC resistance, might relate to the increased risk of venous thrombosis associated with tamoxifen treatment.