Development and validation of cell-based ELISA for the quantification of trastuzumab in human plasma

Trastuzumab is a therapeutic monoclonal antibody against the Her2 oncoprotein, which is over-expressed in approximately 30% of breast cancers, and is now used routinely in the management of early and metastatic Her2+ disease. However, not all Her2+ breast cancer patients respond to trastuzumab and the pharmacodynamic and pharmacokinetic parameters behind this variation in response are unknown. Pharmacological investigations into variable response to trastuzumab have been hampered by the lack of a published feasible method to determine trastuzumab concentration in plasma. Here we describe the development and validation of a cell-based ELISA to measure trastuzumab in human plasma. The assay specifically measures the interaction between trastuzumab and Her2 and has a dynamic range of between 10 and 120 microg/ml. The mean intra-assay and inter-assay variability of the ELISA was 9%. Trastuzumab in plasma was stable for at least 10 weeks at -20 degrees C and 72 h at 4 degrees C, and was unaffected by 5 freeze/thaw cycles. Having validated the assay, the trough plasma trastuzumab concentrations of 30 patients being treated for metastatic or early disease were measured. The median trough concentration was 62 (range 21 to 441) microg/ml. This cell-based ELISA method has undergone appropriate validation and is suitable for quantification of trastuzumab in the plasma of patients treated with Herceptin.

NAD(P)H:Quinone Oxidoreductase 1 and NRH:Quinone Oxidoreductase 2 Activity and Expression in Bladder and Ovarian Cancer and Lower NRH:Quinone Oxidoreductase 2 Activity Associated with an NQO2 Exon 3 Single-Nucleotide Polymorphism

PURPOSE

NRH:quinone oxidoreductase 2 (NQO2) is a homologue of NAD(P)H:quinone oxidoreductase 1 (NQO1). Despite 54% homology with human NQO1, NQO2 has little endogenous enzymatic activity. However, NQO2 has potential as a therapeutic target because the addition of the nonbiogenic electron donor dihydronicotinamide riboside (NRH) selectively potentiates the bioactivation of the alkylating agent tretazicar (CB 1954). The NQO activity of ovarian and bladder tumors was determined and the effect of NQO polymorphisms on NQO activity was investigated.

EXPERIMENTAL DESIGN

Intraperitoneal ovarian metastases and bladder tumor clinical samples were analyzed for NQO1 and NQO2 activity, mRNA expression by semiquantitative reverse transcription-PCR, and genotype by RFLP analysis.

RESULTS

NQO1 activity was higher in the bladder cohort than in the ovarian cohort (0-283 and 0-30 nmol/min/mg, respectively; P < 0.0001). In contrast, NQO2 activity was higher in the ovarian tissue than in the bladder samples (0.15-2.27 and 0-1.14 nmol/min/mg, respectively; P = 0.0004). In both cohorts, the NQO1 C609T single-nucleotide polymorphism (SNP) was associated with approximately 7-fold lower NQO1 activity. The NQO2 exon 3 T14055C SNP was associated with lower NQO2 activity relative to wild-type [median values of 0.18 and 0.37 nmol/min/mg in the bladder samples (P = 0.007) and 0.82 and 1.16 nmol/min/mg in the ovarian cohort (P = 0.034)].

CONCLUSION

This is the first observation reporting an apparent association between an NQO2 exon 3 SNP and lower enzymatic activity. The high NQO2 activity of intraperitoneal ovarian metastases relative to other tissues indicates a potential for tretazicar therapy in the treatment of this disease. In contrast, the low level of NQO1 activity and expression relative to other tissues suggests that NQO1-directed therapies would not be appropriate.

Reduction of mitomycin C is catalysed by human recombinant NRH:quinone oxidoreductase 2 using reduced nicotinamide adenine dinucleotide as an electron donating co-factor

NRH:Quinone Oxidoreductase 2 (NQO2) has been described as having no enzymatic activity with nicotinamide adenine dinucleotide (NADH) or NADPH as electron donating cosubstrates. Mitomycin C (MMC) is both a substrate for and a mechanistic inhibitor of the NQO2 homologue NQO1. NRH:quinone oxidoreductase 2 catalysed the reduction of MMC at pH 5.8 with NADH as a co-factor. This reaction results in species that inhibit the NQO2-mediated metabolism of CB1954. In addition, MMC caused an increase in DNA cross-links in a cell line transfected to overexpress NQO2 to an extent comparable to that observed with an isogenic NQO1-expressing cell line. These data indicate that NQO2 may contribute to the metabolism of MMC to cytotoxic species.

The precautionary principle and electric and magnetic fields

Current environmental regulation represents a paternalistic policy, more concerned to avoid false postives than false negatives, limiting opportunities for individuals to make choices between risk-avoidance and risk-taking alternatives. For example, many exposures to magnetic fields could be reduced at little or no cost but are not considered seriously, owing to the uncertainty of risk and the concern to avoid false positives. Even though precautionary ap proaches that focus on avoiding false negatives often do not lead to adverse economic consequences or irrational choices, such approaches usually are not taken. The value of autonomy and the proper role of governmental paternalism with respect to environmental policy need to be considered more carefully in environmental decision making.

Pharmacist-led medication review in patients over 65: a randomized, controlled trial in primary care

BACKGROUND

regular medication review has been recommended for those over 75 and those on multiple drug therapy. Pharmacists are a potential source of assistance in reviewing medication. Evidence of the benefits of this process is needed.

OBJECTIVE

to study the effect of medication review led by a pharmacist on resolution of pharmaceutical care issues, medicine costs, use of health and social services and health-related quality of life.

DESIGN

randomized, controlled trial.

SETTING

general medical practices in the Grampian region of Scotland.

SUBJECTS

patients aged at least 65 years, with at least two chronic disease states who were taking at least four prescribed medicines regularly.

METHODS

pharmacists reviewed the drug therapy of 332 patients, using information obtained from the practice computer, medical records and patient interviews. In 168 patients, a pharmaceutical care plan was then drawn up and implemented. The 164 control patients continued to receive normal care. All outcome measures were assessed at baseline and after 3 months.

RESULTS

all patients had at least two pharmaceutical care issues at baseline. Half of these were identified from the prescription record, the rest from notes and patient interview. Of all the issues, 21% were resolved by information found in notes and 8.5% by patient interview. General practitioners agreed with 96% of all care issues documented on the care plans in the intervention group. At the time of follow-up, 70% of the remaining care issues had been resolved in the intervention group, while only 14% had been resolved in the control group. There were no changes in medicine costs or health-related quality of life in either group. There were small increases in contacts with health-care professionals and slightly fewer hospital admissions among the intervention group than the control group.

CONCLUSIONS

pharmacist-led medication review has the capacity to identify and resolve pharmaceutical care issues and may have some impact on the use of other health services.

Trends in operative vaginal delivery rates and associated maternal complication rates in an inner-city hospital

OBJECTIVE

The aims of this study were to determine trends in operative vaginal delivery rates in a large inner-city hospital and to assess associated risks.

STUDY DESIGN

We performed a retrospective cohort study (1980-1996) of women with singleton term pregnancies who underwent operative vaginal delivery at Grady Memorial Hospital, Atlanta. Maternal complication rates were compared between forceps-assisted and vacuum-assisted methods.

RESULTS

There was a decline in forceps-assisted deliveries during the 1980s and an increase during the 1990s. The vacuum-assisted delivery rate was exceedingly low during the 1980s and increased during the 1990s. Women who underwent forceps-assisted delivery were more likely to be <24 years old, to be nulliparous, and to have had regional anesthesia, midline episiotomies, and infant presentations other than occipitoanterior (P <.001). Women who underwent forceps-assisted deliveries had increased risks of postpartum infection, cervical laceration, prolonged hospital stay, perineal laceration, and postpartum complications.

CONCLUSION

There were upward trends in the rates of operative vaginal delivery at this inner-city hospital. Women who underwent forceps-assisted delivery had greater rates of maternal complications than did those who underwent vacuum-assisted delivery.

Sickle cell disease in pregnancy: twenty years of experience at Grady Memorial Hospital, Atlanta, Georgia

OBJECTIVE

We compared pregnancy outcomes among women with sickle cell disease with outcomes for African American women without the disease.

STUDY DESIGN

We selected 127 deliveries in women with sickle cell disease (hemoglobin SS or hemoglobin SC) that occurred between 1980 and 1999. A control group of 129 deliveries by African American women with normal hemoglobin (hemoglobin AA) was also selected. Evaluated pregnancy outcomes included low birth weight, prematurity, intrauterine growth restriction, antepartum hospital admission, preterm labor or preterm premature rupture of membranes, postpartum infection, preeclampsia, pyelonephritis, intrauterine fetal death, perinatal mortality, and maternal mortality.

RESULTS

Compared with deliveries among women with hemoglobin AA, deliveries among women with hemoglobin SS or hemoglobin SC were at increased risk for intrauterine growth restriction, antepartum hospital admission, and postpartum infection. In addition, deliveries among women with Hb SS were more likely to be complicated by low birth weight, prematurity, and preterm labor or preterm premature rupture of membranes when compared with deliveries among women with hemoglobin AA. There were no significant differences among the groups (hemoglobin SS, hemoglobin SC, and hemoglobin AA) in terms of perinatal deaths; there were no maternal deaths in the study population.

CONCLUSION

Those caring for women with sickle cell disease should be aware that they are at increased risk for pregnancy complications, although overall pregnancy outcome is favorable.

Postoperative morbidity associated with cesarean delivery among human immunodeficiency virus-seropositive women

OBJECTIVE

The aim of this study was to compare the complication rates associated with cesarean delivery between human immunodeficiency virus-seropositive women with those among a matched group of human immunodeficiency virus-seronegative subjects.

STUDY DESIGN

We conducted a case-control study of 86 human immunodeficiency virus-seropositive women undergoing cesarean delivery between the years 1992 and 2000 at a large, urban teaching institution and a control group of 86 human immunodeficiency virus-seronegative women matched for age, race, year of delivery, and delivery indications. Data were analyzed with the chi2 test and odds ratios. Among human immunodeficiency virus-seropositive women, complications were further stratified according to maternal disease status and use of antiretroviral therapy.

RESULTS

Human immunodeficiency virus-seropositive women were significantly more likely than control women to have minor postoperative complications (66.3% vs 41.8%; odds ratio, 2.73; 95% confidence interval, 1.40-6.10), of which febrile morbidity was the most common (62.8% vs 42.7%; P =.003). There was no difference between the groups in the rate of major complications (9.3% vs 3.4%; odds ratio, 2.84; 95% confidence interval, 0.65-14.06). Zidovudine use was associated with a decrease in the maternal morbidity rate (odds ratio, 0.31; 95% confidence interval, 0.07-1.03).

CONCLUSION

Postoperative morbidity among human immunodeficiency virus-seropositive women undergoing cesarean delivery was not different from that in a matched control population.

Societal response to Hurricane Mitch and intra- versus intergenerational equity issues: whose norms should apply?

Late in the 1998 hurricane season, Central America was slammed by a devastating hurricane. Honduras, Nicaragua. El Salvador, Guatemala, and Belize were greatly impacted by Hurricane Mitch, one of the deadliest storms to affect the region in the past 200 years. The economies of each of these countries were badly affected. In the case of Honduras-at the time the fourth-poorest country in Latin America-its president suggested that 50 years of progress had been wiped out by the floods and mudslides associated with this relatively short-lived storm system. Humanitarian assistance poured into the region in the first months following the disaster. As of mid-2000, various national, bilateral, international, and nongovernmental programs were in progress or on the drawing board for recovery, reconstruction, and renewed development of the worst affected countries. Using Honduras as a case study, some of the ethical issues that abound in the decisions of whom to help, when, and how to help them in the wake of such an extreme climate-related human tragedy are examined. Should development assistance be focused on those who have been directly and adversely affected by this storm, or should the emphasis be on reducing the risk of exposure by future generations to such disasters? Is there yet another approach that seeks to protect future generations from similar harm while at the same time assisting present-day victims to get through their hardships?

Responses of young Xenopus laevis tadpoles to light dimming: possible roles for the pineal eye

When the light is dimmed, the pineal eye of hatchling Xenopus laevis tadpoles excites the central pattern generator for swimming, but the behavioural significance of pineal excitation is unclear. We show that tadpoles spend 99 % of their time hanging from the surface meniscus or solid objects using mucus secreted by a cement gland on the head. Attachment inhibits swimming, but unattached tadpoles swim spontaneously. Provided that their pineal eye is intact, they attach closer to the water surface in the dark than in the light and attach preferentially to the underside of floating objects that cast shadows. Dimming causes tadpoles swimming horizontally to turn upwards and is very effective in initiating upward swimming in unattached tadpoles. Similar pineal-dependent responses during swimming are present up to stage 44. Pinealectomy blocks responses to dimming at all stages. Recordings from immobilised tadpoles reveal that light dimming induces faster fictive swimming and that pineal activity is increased for up to 20 min during sustained light dimming. We suggest that the increase in pineal discharge during dimming increases the probability of upward swimming and, in this way, increases the probability of tadpoles attaching to objects higher in the water column that cast shadows.

A possible pathway connecting the photosensitive pineal eye to the swimming central pattern generator in young Xenopus laevis tadpoles

The pineal eye of young Xenopus laevis tadpoles mediates a swimming response to dimming. Our aim was to define pathways that allow pineal photoreceptors to influence the swimming central pattern generator (CPG) in the hindbrain and spinal cord. Retrograde filling with horseradish peroxidase (HRP) and carboxyfluorescein showed that: (1) pineal ganglion cells do not project to the hindbrain, and (2) diencephalic/mesencephalic descending (D/MD) neurons, which could be contacted by pineal ganglion cell axons, do project to the hindbrain. Lesion experiments demonstrated that ganglion cell axons form ipsilateral and contralateral connections, either of which is sufficient to mediate a swimming response. Latency measurements suggest that the contralateral pathway is stronger than the ipsilateral one. Multiple unit recordings from the midbrain in the region of the D/MD neurons showed short latency activity in response to dimming or a brief current pulse to pineal axons. This activity could last for many seconds after the stimulus. Pharmacological experiments showed that it depended on synaptic excitation and suggested that the ganglion cell transmitter is glutamate. If pineal ganglion cells excite midbrain D/MD neurons on both sides of the brain, the D/MD neuron projections to the hindbrain could excite the swimming CPG and initiate swimming.