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Biomedical subjects

D Crowther

Publications and source records attributed to D Crowther.

At least 19 recordsLinked to original sources

ChlVPP/EVA hybrid versus the weekly VAPEC-B regimen for previously untreated Hodgkin's disease.

PURPOSE: To test the hypothesis that a chemotherapy regimen of relatively low toxicity and 11 weeks' duration (doxorubicin, cyclophosphamide, etoposide, vincristine, bleomycin, and prednisolone [VAPEC-B]) is at least as effective in terms of disease control as 6 months' treatment with chlorambucil, vinblastine, procarbazine, and prednisone/etoposide, vincristine, and doxorubicin (ChlVPP/EVA hybrid), which is associated with a high risk of permanent sterility. PATIENTS AND METHODS: Two hundred eighty-two patients with previously untreated Hodgkin's disease, clinical stages I/II (plus mediastinal bulk and/or B symptoms) and clinical stages III/IV were randomized at three United Kingdom and one Italian center to receive either six monthly cycles of ChlVPP/EVA hybrid or 11 weekly cycles of VAPEC-B. After chemotherapy and a restaging evaluation, radiotherapy was administered to sites of previous bulk or residual radiographic abnormality before patients were observed off treatment. RESULTS: Further accrual to the trial was halted at the planned third interim analysis in September 1996. After a median follow-up of 4.9 years, freedom from progression (FFP), event-free survival (EFS), and overall survival (OS) are all significantly better in the population treated with ChlVPP/EVA than VAPEC-B, where the comparative 5-year results are 82% and 62% (FFP), 78% and 58% (EFS), and 89% and 79% (OS), respectively. The superiority of ChlVPP/EVA was seen in both low-risk and intermediate/high-risk patients, although subset analysis suggested that ChlVPP/EVA and VAPEC-B produce equivalent results in the best-prognosis patients (Hasenclever score <or= 2, nonbulky disease). CONCLUSION: Apart from possibly in the best-prognosis group, where results are equivalent, ChlVPP/EVA hybrid produces significantly better FFP, EFS, and OS than VAPEC-B in patients with previously untreated Hodgkin's disease.

Adolescent↗

A quantitative and qualitative pilot study of the perceived benefits of autogenic training for a group of people with cancer.

This paper describes the application of autogenic training (AT), a technique of deep relaxation and self-hypnosis, in patients diagnosed with cancer,with the aim of increasing their coping ability, and reports the results of a questionnaire survey performed before and after an AT course. A reduction in arousal and anxiety can help individuals to perceive their environment as less hostile and threatening, with implications for improved perceived coping ability. Complementary therapies are considered useful in enhancing symptom relief, overall well-being and self-help when used as adjuvant therapies to allopathic medical interventions. The present study aimed to validate, in an Irish context, the effectiveness of AT as a complementary therapy for patients with cancer. Each participant completed a Hospital Anxiety and Depression Scale and Profile of Mood States questionnaire before and after a 10-week AT course. The results indicated a significant reduction in anxiety and increase in 'fighting spirit' after compared with before training, with an improved sense of coping and improved sleep being apparent benefits of AT practice.

Adaptation, Psychological↗

Identification and characterization of a novel human vanilloid receptor-like protein, VRL-2.

Remarkable progress has been made recently in identifying a new gene family related to the capsaicin (vanilloid) receptor, VR1. Using a combination of in silico analysis of expressed sequence tag (EST) databases and conventional molecular cloning, we have isolated a novel vanilloid-like receptor, which we call VRL-2, from human kidney. The translated gene shares 46% and 43% identity with VR1 and VRL-1, respectively, and maps to chromosome 12q23-24.1, a locus associated with bipolar affective disorder. VRL-2 mRNA was most strongly expressed in the trachea, kidney, and salivary gland. An affinity-purified antibody against a peptide incorporating the COOH terminal of the receptor localized VRL-2 immunolabel in the distal tubules of the kidney, the epithelial linings of both trachea and lung airways, serous cells of submucosal glands, and mononuclear cells. Unlike VR1 and VRL-1, VRL-2 was not detected in cell bodies of dorsal root ganglia (DRG) or sensory nerve fibers. However, VRL-2 was found on sympathetic and parasympathetic nerve fibers, such as those innervating the arrector pili smooth muscle in skin, sweat glands, intestine, and blood vessels. At least four vanilloid receptor-like genes exist, the newest member, VRL-2 is found in airway and kidney epithelia and in the autonomic nervous system.

Amino Acid Sequence↗

Randomized phase III study comparing conventional-dose doxorubicin plus ifosfamide versus high-dose doxorubicin plus ifosfamide plus recombinant human granulocyte-macrophage colony-stimulating factor in advanced soft tissue sarcomas: A trial of the European Organization for Research and Treatment of Cancer/Soft Tissue and Bone Sarcoma Group.

PURPOSE: This randomized multicenter study was designed to compare the activity of a high-dose doxorubicin-containing chemotherapy regimen with a conventional standard-dose regimen in adult patients with advanced soft tissue sarcomas (ASTS). PATIENTS AND METHODS: Between 1992 and 1995, 314 patients were randomized to receive a standard-dose regimen (arm A), containing doxorubicin (50 mg/m(2) on day 1) and ifosfamide (5 g/m(2) on day 1), or an intensified regimen (arm B), combining doxorubicin (75 mg/m(2) on day 1), the same ifosfamide dose, and recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF; sargramostim, 250 microgram/m(2) on days 3 to 16); all courses were repeated every 3 weeks. RESULTS: The median age of the 294 eligible patients was 50 years. They received a median of five chemotherapy cycles. The median dose and relative doxorubicin dose-intensity achieved were 245 mg and 97% in arm A and 360 mg and 99% in arm B, respectively. Thirty-eight percent and 23% of patients presented with leiomyosarcomas and liver metastases, respectively. Objective responses were observed in 31 (21%) of 147 assessable patients in arm A and in 31 (23.3%) of 133 in arm B (P =.65). No change was observed in 41.6% and 46.2% of patients in arm A and B, respectively. Progression-free survival (PFS) was significantly longer in the intensive arm (P =.03). The median duration of the time to progression was 19 weeks in the conventional arm and 29 weeks in the intensified arm. There was no difference in overall survival (P =.98) between the two therapeutic arms. Toxicities were manageable in both arms. A grade 3/4 neutropenia and infection occurred in 92% and 4.6% of patients in arm A, respectively, and in 90% and 16.6% in arm B, respectively. Grade 3/4 thrombocytopenia was more frequent in arm B. CONCLUSION: The use of rhGM-CSF allowed safe escalation of chemotherapy doses. Despite a 50% increase of the doxorubicin dose-intensity, the high-dose regimen failed to demonstrate any impact on survival in patients with ASTS. The low complete response rate, the high incidence of leiomyosarcomas, and liver metastases may in part explain these results. However, the lengthening of the PFS in the intensive arm, because of the quality of stable disease and inappropriate tumor evaluation policies that potentially lead to an underestimation of antitumor activity, does not definitively refute the use of a high-dose chemotherapy regimen in selected patients with ASTS.

Adult↗

Decreasing estrogen in nonpregnant women lowers uterine myometrial type I nitric oxide synthase protein expression.

OBJECTIVE: Our purpose was to study the effect of estrogen on myometrial nitric oxide synthase. STUDY DESIGN: Twenty-four women were randomly assigned to treatment with gonadotropin-releasing hormone agonist or placebo for 8 weeks before hysterectomy, at which time samples of myometrium were collected and the serum levels of estrogen, nitrate, and nitrite measured. Myometrial nitric oxide synthase was measured with the arginine-citrulline assay. The levels of endothelial nitric oxide synthase and neuronal nitric oxide synthase were determined by Western blot analysis. RESULTS: Myometrial nitric oxide synthase was 88% calcium dependent but only partially calmodulin dependent. Women treated with gonadotropin-releasing hormone agonist had postmenopausal levels of estradiol and had significantly lower levels of myometrial neuronal nitric oxide synthase than those in the control group. Total, endothelial, and inducible nitric oxide synthase levels in the myometrium were unchanged, as were serum nitrite and nitrate levels. CONCLUSION: Neuronal nitric oxide synthase is regulated in the myometrium by estrogen. Myometrial nitric oxide synthase is not all calmodulin dependent; this may represent the activity of a novel nitric oxide synthase isoform.

Adult↗

Further investigation of the role of HLA-DPB1 in adult Hodgkin's disease (HD) suggests an influence on susceptibility to different HD subtypes.

It has been suggested in a number of studies that susceptibility to adult Hodgkin's disease (HD) is influenced by the HLA class II region, and specifically by alleles at the HLA-DPB1 locus. Since HD is diagnostically complex, it is not clear whether different HLA-DPB1 alleles confer susceptibility to different HD subtypes. To clarify this we have extended a previous study to type DPB1 alleles in 147 adult HD patients from a single centre. We have analysed patients with nodular sclerosing (NS), mixed cellularity (MC) or lymphocyte predominant (LP) HD, and gender in relation to HLA-DPB1 type, in comparison with 183 adult controls. The results confirmed previously reported associations of DPB1*0301 with HD susceptibility (relative risk (RR) = 1.42; 95% confidence interval (CI) 0.86-2.36) and DPB1*0201 with resistance to HD (RR = 0.49; CI 0.27-0.90). However, analysis by HD subtype and gender showed that *0301-associated susceptibility was confined to females with HD (RR = 2.46; CI 1.02-5.92), and *0201-associated resistance to females with NS-HD (RR = 0.28; CI 0.10-0.79). Susceptibility to NS-HD was also associated in females with *1001 (RR = 11.73; CI 1.32-104.36), and resistance with *1101 (RR = 0.08; CI 0.01-0.65). In contrast, susceptibility to LP-HD was associated in males with *2001 (RR = 32.14; CI 3.17-326.17), and to MC-HD with *3401 (RR = 16.78; CI 2.84-99.17). Comparison of DPB1-encoded polymorphic amino-acid frequencies in patients and controls showed that susceptibility to MC-HD was associated with Leucine at position 35 of DPB1 (RR = 8.85; CI 3.04-25.77), Alanine-55 (RR = 15.17; CI 2.00-115.20) and Valine-84 (RR = 15.94; CI 3.55-71.49). In contrast, Glutamic acid 69 was significantly associated with resistance to MC-HD (RR = 0.14; CI 0.03-0.60). Certain DPB1 alleles and individual DPbeta1 polymorphic amino acid residues may thus affect susceptibility and resistance to specific HD subtypes. This may be through their influence on the binding of peptides derived from an HD-associated infectious agent, and the consequent effect on immune responses to the agent.

Adolescent↗

Prognostic factors for the outcome of chemotherapy in advanced soft tissue sarcoma: an analysis of 2,185 patients treated with anthracycline-containing first-line regimens--a European Organization for Research and Treatment of Cancer Soft Tissue and Bone Sarcoma Group Study.

PURPOSE: A total of 2,185 patients with advanced soft tissue sarcomas who had been treated in seven clinical trials investigating the use of doxorubicin- or epirubicin-containing regimens as first-line chemotherapy were studied in this prognostic-factor analysis. PATIENTS AND METHODS: Overall survival time (median, 51 weeks) and response to chemotherapy (26% complete response or partial response) were the two end points. The cofactors were sex; age; performance status; prior therapies; the presence of locoregional or recurrent disease; lung, liver, and bone metastases at the time of entry onto the trial; long time period between the initial diagnosis of sarcoma and entry onto the study; and histologic type and grade. RESULTS: Univariate analyses showed (a) a significant, favorable influence of good performance status, young age, and absence of liver metastases on both survival time and response rate, (b) a significant, favorable influence of low histopathologic disease grade on survival time, despite a significantly lower response rate, (c) increased survival time for patients with a long time period between the initial diagnosis of sarcoma and entry onto the study, despite equivalent response rates, and (d) increased survival time with liposarcoma or synovial sarcoma, a decreased survival time with malignant fibrous histiocytoma, a lower response rate with leiomyosarcoma, and a higher response rate with liposarcoma (P < .05 for all log-rank and chi2 tests). The Cox model selected good performance status (P < .0001), absence of liver metastases (P = .0001), low histopathologic grade (P = .0002), long time lapse since initial diagnosis (P = .0004), and young age (P = .0045) as favorable prognostic factors of survival time. The logistic model selected absence of liver metastases (P < .0001), young age (P = .0024), high histopathologic grade (P = .0051), and liposarcoma (P = .0065) as favorable prognostic factors of response rate. CONCLUSION: This analysis demonstrates that for advanced soft tissue sarcoma, response to chemotherapy is not predicted by the same factors as is overall survival time. This needs to be taken into account in the interpretation of trials assessing the value of new agents for this disease on the basis of response to treatment.

Adult↗

High-performance liquid chromatographic assay for the novel antitumor drug, bryostatin-1, incorporating a serum extraction technique.

An HPLC assay incorporating a solid-phase extraction technique has been devised for bryostatin-1. Quantitation of bryostatin was found to be linear over the concentration range 0.012-25 microg/ml (0.2-25 ng on column) and was found to have a limit of detection of 0.2 ng on column, with a correlation coefficient of 0.9999. Following extraction of bryostatin over a range of concentrations from horse serum (0.012-25 microg/ml) and human serum (0.01-0.32 microg/ml) using a 100-mg C18 solid-phase extraction cartridge, extraction efficiencies consistently greater than 90% were obtained for extraction from horse serum and varied between 57 and 85% from human serum. However, on extending this work to blood samples from patients undergoing therapy with bryostatin-1, the drug was not detectable even at the maximum dose given, demonstrating the rapid loss of this agent from peripheral circulation.

Animals↗

Recombinant human granulocyte colony-stimulating factor (filgrastim) following high-dose chemotherapy and peripheral blood progenitor cell rescue in high-grade non-Hodgkin's lymphoma: clinical benefits at no extra cost.

In order to evaluate the potential clinical and economic benefits of granulocyte colony-stimulating factor (G-CSF, filgrastim) following peripheral blood progenitor cells (PBPC) rescue after high-dose chemotherapy (HDCT), 23 consecutive patients aged less than 60 years with poor-prognosis, high-grade non-Hodgkin's lymphoma (NHL) were entered into a prospective randomized trial between May 1993 and September 1995. Patients were randomized to receive either PBPC alone (n = 12) or PBPC+G-CSF (n = 11) after HDCT with busulphan and cyclophosphamide. G-CSF (300 microg day[-1]) was given from day +5 until recovery of granulocyte count to greater than 1.0 x 10(9) l(-1) for 2 consecutive days. The mean time to achieve a granulocyte count > 0.5 x 10(9) l(-1) was significantly shorter in the G-CSF arm (9.7 vs 13.2 days; P<0.0001) as was the median duration of hospital stay (12 vs 15 days; P = 0.001). In addition the recovery periods (range 9-12 vs 11-17 days to achieve a count of 1.0 x 10(9) l[-1]) and hospital stays (range 11-14 vs 13-22 days) were significantly less variable in patients receiving G-CSF in whom the values clustered around the median. There were no statistically significant differences between the study arms in terms of days of fever, documented episodes of bacteraemia, antimicrobial drug usage and platelet/red cell transfusion requirements. Taking into account the costs of total occupied-bed days, drugs, growth factor usage and haematological support, the mean expenditure per inpatient stay was pound sterling 6500 (range pound sterling 5465-pound sterling 8101) in the G-CSF group compared with pound sterling 8316 (range pound sterling 5953-pound sterling 15,801) in the group not receiving G-CSF, with an observed mean saving of 1816 per patient (or 22% of the total cost) in the G-CSF group. This study suggests that after HDCT and PBPC rescue, the use of G-CSF leads to more rapid haematological recovery periods and is associated with a more predictable and shorter hospital stay. Furthermore, and despite the additional costs for G-CSF, these clinical benefits are not translated into increased health care expenditure.

Adult↗

Bryostatin 1-tamoxifen combinations show synergistic effects on the inhibition of growth of P388 cells in vitro.

This study shows that combinations of bryostatin 1, a novel modulator of protein kinase C currently under clinical evaluation, with the anti-oestrogenic agent tamoxifen caused a large synergistic enhancement of growth inhibition in P388 cells in vitro. The growth-inhibitory effects of bryostatin 1 in the presence of non-inhibitory concentrations of tamoxifen were increased by approximately 200-fold, whereas growth inhibition by tamoxifen in the presence of non-inhibitory concentrations of bryostatin 1 were increased over 30-fold. These data have been confirmed by isobologram analysis. The precise mechanism underlying this effect is unknown, although preliminary data implicating protein kinase C is presented. The magnitude of this synergistic effect, together with evidence of clinical responses seen when these agents were given sequentially in ovarian cancer, merits further study.

Animals↗

Chemotherapy in advanced ovarian cancer: four systematic meta-analyses of individual patient data from 37 randomized trials. Advanced Ovarian Cancer Trialists' Group.

The purpose of this systematic study was to provide an up to date and reliable quantitative summary of the relative benefits of various types of chemotherapy (non-platinum vs platinum, single-agent vs combination and carboplatin vs cisplatin) in the treatment of advanced ovarian cancer. Also, to investigate whether well-defined patient subgroups benefit more or less from cisplatin- or carboplatin-based therapy. Meta-analyses were based on updated individual patient data from all available randomized controlled trials (published and unpublished), including 37 trials, 5667 patients and 4664 deaths. The results suggest that platinum-based chemotherapy is better than non-platinum therapy, show a trend in favour of platinum combinations over single-agent platinum, and suggest that cisplatin and carboplatin are equally effective. There is no good evidence that cisplatin is more or less effective than carboplatin in any particular subgroup of patients.

Antineoplastic Agents↗

High-dose epirubicin is not an alternative to standard-dose doxorubicin in the treatment of advanced soft tissue sarcomas. A study of the EORTC soft tissue and bone sarcoma group.

The activity and toxicity of single-agent standard-dose doxorubicin were compared with that of two schedules of high-dose epirubicin. A total of 334 chemonaive patients with histologically confirmed advanced soft-tissue sarcomas received (A) doxorubicin 75 mg m(-2) on day 1 (112 patients), (B) epirubicin 150 mg m(-2) on day 1 (111 patients) or (C) epirubicin 50 mg m(-2) day(-1) on days 1, 2 and 3 (111 patients); all given as bolus injection at 3-week intervals. A median of four treatment cycles was given. Median age was 52 years (19-70 years) and performance score 1 (0-2). Of 314 evaluable patients, 45 (14%) had an objective tumour response (eight complete response, 35 partial response). There were no differences among the three groups. Median time to progression for groups A, B and C was 16, 14 and 12 weeks, and median survival 45, 47 and 45 weeks respectively. Neither progression-free (P = 0.93) nor overall survival (P = 0.89) differed among the three groups. After the first cycle of therapy, two patients died of infection and one owing to cardiovascular disease, all on epirubicin. Both dose schedules of epirubicin were more myelotoxic than doxorubicin. Cardiotoxicity (> or = grade 3) occurred in 1%, 0% and 2% respectively. Regardless of the schedule, high-dose epirubicin is not a preferred alternative to standard-dose doxorubicin in the treatment of patients with advanced soft-tissue sarcomas.

Adult↗

CAMPATH-1H monoclonal antibody in therapy for previously treated low-grade non-Hodgkin's lymphomas: a phase II multicenter study. European Study Group of CAMPATH-1H Treatment in Low-Grade Non-Hodgkin's Lymphoma.

PURPOSE: CAMPATH-1H is a human immunoglobulin G1 (IgG1) anti-CD52 monoclonal antibody (MAb) that binds to nearly all B-cell and T-cell lymphomas. We report here the results of a multicenter phase II trial of CAMPATH-1H in patients with advanced, low-grade non-Hodgkin's lymphoma (NHL) who were previously treated with chemotherapy. PATIENTS AND METHODS: Fifty patients who had relapsed (n=25) after or were resistant (n = 25) to chemotherapy were treated with CAMPATH-1H 30 mg administered as a 2-hour intravenous (i.v.) infusion three times weekly for a maximum period of 12 weeks. RESULTS: Six patients (14%) with B-cell lymphomas achieved a partial remission (PR). Patients with mycosis fungoides appeared to respond more frequently (50%; four of eight patients, which included two complete remissions [CRs]). Lymphoma cells were rapidly eliminated from blood in 16 of 17 patients (94%). CR in the bone marrow was obtained in 32% of the patients. Lymphoma skin lesions disappeared completely in four of 10 patients and partial regression was obtained in three patients. Lymphadenopathy and splenomegaly were normalized in only 5% and 15% of patients, respectively. Lymphopenia (< 0.5 x 10(9)/L) occurred in all patients. World Health Organization (WHO) grade IV neutropenia occurred in 14 patients (28%). Opportunistic infections were diagnosed in seven patients and nine patients had bacterial septicemia. Death related to infectious complications occurred in three patients. CONCLUSION: CAMPATH-1H had a significant but limited activity in patients with advanced, heavily pretreated NHL. The most pronounced effects were noted in the blood and bone marrow and in patients with mycosis fungoides. The risk for serious infectious complications needs to be considered for severely ill patients who are evaluated for CAMPATH-1H treatment.

Adult↗

Meta-analysis of chemotherapy versus combined modality treatment trials in Hodgkin's disease. International Database on Hodgkin's Disease Overview Study Group.

DESIGN: To perform a meta-analysis of all randomized trials that compared chemotherapy (CT) alone versus combined modality treatment (CT + radiotherapy [RT]) for which individual patient data could be made available. PATIENTS AND METHODS: Data on 1,740 patients treated on 14 different trials that included 16 relevant comparisons have been analysed. Eight comparisons were designed to evaluate the benefit of additional RT after the same CT (CT1 v CT1 + RT; additional RT design). Eight comparisons were designed to evaluate whether RT in a combined modality setting can be substituted by CT using either more cycles of the same CT or regimens that contain additional drugs (CT1 + CT2 v CT1 + RT or CT1 v CT2 + RT; parallel RT/CT design). RESULTS: Additional RT showed an 11% overall improvement in tumor control rate after 10 years (P = .0001; 95% confidence interval [CI], 4% to 18%). No difference could be detected with respect to overall survival (P = .57; 95% CI, -10% to 4%). In contrast, when combined modality treatment was compared with CT alone in the parallel-design trials, no difference could be detected in tumor control rates (P = .43; 95% CI, -6% to 9%), but overall survival was significantly better after 10 years in the group that did not receive RT (P = .045; 8% difference; 95% CI, 1% to 15%). There were significantly fewer fatal events among patients in continuous complete remission (relative risk [RR], 1.73; 95% CI, 1.17 to 2.53; P = .005) if no RT was given. CONCLUSION: Combined modality treatment in patients with advanced-stage Hodgkin's disease overall has a significantly inferior long-term survival outcome than CT alone if CT is given over an appropriate number of cycles. The role of RT in this setting is limited to specific indications.

Antineoplastic Agents↗

Randomized comparison of progenitor-cell mobilization using chemotherapy, stem-cell factor, and filgrastim or chemotherapy plus filgrastim alone in patients with ovarian cancer.

PURPOSE: This was the first randomized study to investigate the efficacy of peripheral-blood progenitor cell (PBPC) mobilization using stem-cell factor (SCF) in combination with filgrastim (G-CSF) following chemotherapy compared with filgrastim alone following chemotherapy. PATIENTS AND METHODS: Forty-eight patients with ovarian cancer were treated with cyclophosphamide and randomized to receive filgrastim 5 microg/kg alone or filgrastim 5 microg/kg plus SCF. The dose of SCF was cohort-dependent (5, 10, 15, and 20 microg/kg), with 12 patients in each cohort, nine of whom received SCF plus filgrastim and the remaining three patients who received filgrastim alone. On recovery from the WBC nadir, patients underwent a single apheresis. RESULTS: SCF in combination with filgrastim following chemotherapy enhanced the mobilization of progenitor cells compared with that produced by filgrastim alone following chemotherapy. This enhancement was dose-dependent for colony-forming unit-granulocyte-macrophage (CFU-GM), burst-forming unit-erythrocyte (BFU-E), and CD34+ cells in both the peripheral blood and apheresis product. In the apheresis product, threefold to fivefold increases in median CD34+ and progenitor cell yields were obtained in patients treated with SCF 20 microg/kg plus filgrastim compared with yields obtained in patients treated with filgrastim alone. Peripheral blood values of CFU-GM, BFU-E, and CD34+ cells per milliliter remained above defined threshold levels longer with higher doses of SCF. The higher doses of SCF offer a greater window of opportunity in which to perform the apheresis to achieve high yields. CONCLUSION: SCF (15 or 20 microg/kg) in combination with filgrastim following chemotherapy is an effective way of increasing progenitor cell yields compared with filgrastim alone following chemotherapy.

Adult↗

Determination of nitrite and nitrate in human serum.

A simple and effective assay for nitrite and nitrate in human serum has been developed using ion chromatography. Initial experiments using isocratic carbonate-bicarbonate elution with conductivity detection on a Dionex QIC system with an AS4A-SC column showed promise but were unsatisfactory because of co-elution problems with nitrite. Carbonate and chloride were investigated as eluents using a gradient system, and direct UV detection at 214 nm was used in place of conductivity detection. Dionex AS4A, AS9A, AS12, Nucleopac PA-100 and Carbopac PA-100 columns were compared for selectivity and resistance to overload. The final method, using a chloride concentration gradient, pH buffering and direct UV detection with a Carbopac PA-100 column, shows good resolution, does not suffer from chloride overload and is simple to use. The method is being used in an investigation of the role of nitric oxide in pre-eclampsia, a hypertensive disorder during pregnancy.

Chromatography, Ion Exchange↗