The control of chlorophyll catabolism and the status of yellowing as a biomarker of leaf senescence

The pathway of chlorophyll catabolism during leaf senescence is known in a fair amount of biochemical and cell biological detail. In the last few years, genes encoding a number of the catabolic enzymes have been characterized, including the key ring-opening activities, phaeophorbide a oxygenase (PaO) and red chlorophyll catabolite reductase (RCCR). Recently, a gene that modulates disassembly of chlorophyll-protein complexes and activation of pigment ring-opening has been isolated by comparative mapping in monocot species, positional cloning exploiting rice genomics resources and functional testing in Arabidopsis. The corresponding gene in pea has been identified as Mendel's I locus (green/yellow cotyledons). Mutations in this and other chlorophyll catabolic genes have significant consequences, both for the course of leaf senescence and senescence-like stress responses, notably hypersensitivity to pathogen challenge. Loss of chlorophyll can occur via routes other than the PaO/RCCR pathway, resulting in changes that superficially resemble senescence. Such 'pseudosenescence' responses tend to be pathological rather than physiological and may differ from senescence in fundamental aspects of biochemistry and regulation.

Multistep ionization of argon clusters in intense femtosecond extreme ultraviolet pulses

The interaction of intense extreme ultraviolet femtosecond laser pulses (lambda = 32.8 nm) from the FLASH free electron laser (FEL) with clusters has been investigated by means of photoelectron spectroscopy and modeled by Monte Carlo simulations. For laser intensities up to 5x10(13) W/cm(2), we find that the cluster ionization process is a sequence of direct electron emission events in a developing Coulomb field. A nanoplasma is formed only at the highest investigated power densities where ionization is frustrated due to the deep cluster potential. In contrast with earlier studies in the IR and vacuum ultraviolet spectral regime, we find no evidence for electron emission from plasma heating processes.

Does fructan have a functional role in physiological traits? Investigation by quantitative trait locus mapping

* The role of fructan in growth and drought-stress responses of perennial ryegrass (Lolium perenne) was investigated in an F(2) mapping family that segregates for carbohydrate metabolism. * A quantitative trait locus approach was used to compare the genetic control of traits. * Growth and drought-stress traits were extremely variable within the family. Most traits had high broad-sense heritability. Quantitative trait loci (QTL) were identified for most traits; the maximum number of QTL per trait was four. Between 11% and 75% of total phenotypic variation was explained. Few growth-trait QTL coincided with previously identified fructan QTL. A cluster of drought-trait QTL was close to two previously identified regions of the genome with tiller base fructan QTL in repulsion. * The high sugar parent contributed few alleles that increased 'reserve-driven' growth or performance during drought-stress. Correlation of growth and drought-stress traits with fructan content was low and increasing fructan content per se would not appear to improve drought resistance. Complex patterns of carbohydrate partitioning and metabolism within the cell may explain contradictory relationships between carbohydrate content and growth/stress-resistance traits.

First-into-man phase I and pharmacokinetic study of XR5944.14, a novel agent with a unique mechanism of action

The bis-phenazine XR5944.14 is a novel cytotoxic agent which intercalates into DNA and inhibits transcription. The objectives of this study were to determine the dose-limiting toxicity (DLT), the maximum tolerated dose (MTD) and to describe the pharmacokinetics (PKs) of XR5944.14 when given at doses ranging from 3.6 to 36 mg m⁻² every 3 weeks to patients with advanced tumours. Twenty-seven patients were treated with a total of 77 cycles. Dose-limiting toxicities occurred at doses ⩾24 mg m⁻². Oral mucositis was the most common DLT. Two patients developed acute renal failure possibly related to the study drug. Other less-severe toxicities were diarrhoea, nausea, vomiting and fatigue. Haematological toxicity was mild. One patient showed an objective partial response. Pharmacokinetic analysis was performed during the first cycle of treatment and plasma was assayed for XR5944.14 using a validated liquid chromatography tandem mass spectrometry. The systemic exposure of XR5944.14 increased more than proportionally with increasing dose, with inter-patient variability increasing from dose level 24 mg m⁻² onwards. The lack of correlation between toxicity and PK values makes it difficult to recommend a dose for further study in phase 2 trials. More work is needed to explain the inter- and intra-individual variation in PKs and pharmacodynamics.

Experimental determination of the ionization potentials of the first five members of the nanodiamond series

The ionization potentials of size- and isomer-selected diamondoids (nanodiamond containing one to five crystal cages) have been measured by means of total-ion-yield spectroscopy. We find a monotonic decrease of the ionization potential with increasing diamondoid size. This experimental result is compared to recent theoretical predictions and comparable investigations on related carbon clusters, the fullerenes, which show isomer effects to be stronger than size dependence.

Long-term follow-up of the hepatitis C HENCORE cohort: response to therapy and occurrence of liver-related complications

The aims of the study were to verify the long-term effect of time on viral clearance in hepatitis C virus (HCV) patients and to find out factors possibly associated with disease progression. A total of 1641 patients recruited from eight European centres in 1996-1997 were re-analysed 5-7 years after inclusion. The occurrence of decompensated cirrhosis, hepatocellular carcinoma (HCC) and liver transplantation was analysed in relation to different host and viral factors. Ninety-three per cent of the HCV patients who had cleared the virus (spontaneously or after antiviral therapy) remained HCV-RNA-negative during follow up and may be considered as 'cured'. Among patients who were sustained responders at inclusion, 2.3% developed liver complications during follow up, and 31% of non-responders did. Advanced age at infection and presence of the human leucocyte antigen (HLA) DRB1*1201-3 allele were possibly associated with a higher rate of progression to decompensated cirrhosis or HCC. Decompensated cirrhosis might be further associated with male gender, non-response to previous therapy, and lack of HLA DRB1*1301 allele, whereas HCC seems to be associated with the presence of the HLA DQ02 allele. Long-term follow up of HCV patients indicates that virological response persists over time and is associated with a very low incidence of liver complications. Advanced age at inclusion, advanced age at infection, viral genotype 1, non-response to previous therapy and possibly some specific HLA alleles are factors independently associated with a faster rate of progression towards liver complications. The large proportion of patients lost to follow up stresses the need for a strengthened and optimized management of HCV patients.

Modern chemotherapy management of recurrent ovarian cancer: a multicentre study

AIMS

The natural history of ovarian cancer has changed over the last 10 years due to more effective drug treatments. The aim of this multicentre audit of the management of recurrent ovarian cancer was to examine the usage of newer drugs in light of the publication of National Institute of Clinical Excellence guidance.

MATERIALS AND METHODS

All patients presenting with a first or subsequent relapse of ovarian cancer between August 2001 and February 2003 in nine UK National Health Service centres were identified. Data were recorded retrospectively and prospectively from point of entry into the study and included the modality of primary cancer treatment, the treatment of each subsequent relapse and outcome.

RESULTS

In total, 245 evaluable patients were entered on to the database. The mean age was 62 years. All patients received a platinum-based chemotherapy regimen as first-line treatment. One hundred and fifty-five patients (63%) went on to receive third-line chemotherapy and 82 (34%) received fourth-line chemotherapy. The median survival from first relapse was estimated to be in excess of 12 months from our data. The efficacies of the chemotherapy agents used are comparable with the results of published phase III trials.

CONCLUSION

This study shows that multicentre audit is feasible and provides useful information on current clinical practice on which to base future research.

Cost effectiveness of interferon alpha or peginterferon alpha with ribavirin for histologically mild chronic hepatitis C

BACKGROUND

For patients with mild chronic hepatitis C the cost effectiveness of antiviral therapy is unknown.

AIMS

To assess whether antiviral therapy (either interferon alpha or peginterferon alpha combined with ribavirin) is cost effective at a mild stage compared with waiting and only treating those cases who progress to moderate disease.

PATIENTS

Cases with mild chronic hepatitis C.

METHODS

A cost effectiveness model which estimates long term costs and outcomes for patients with mild chronic hepatitis C. The model uses effectiveness and cost data from the UK mild hepatitis C randomised controlled trial, combined with estimates of disease progression and cost from observational studies.

RESULTS

Antiviral treatment at a mild rather than a moderate stage improved outcomes measured by quality adjusted life years (QALYS) gained. The mean cost per QALY gained from antiviral treatment with interferon alpha-2b and ribavirin, compared with no treatment at a mild stage, was 4535 pounds sterling (7108 dollars) for patients with genotype non-1 and 25,188 pounds sterling (39,480 dollars) for patients with genotype 1. Providing peginterferon alpha-2b and ribavirin at a mild rather than a moderate stage was also associated with a gain in QALYS; the costs per QALY gained were 7821 pounds sterling (12,259 dollars) for patients with genotype non-1 and 28,409 pounds sterling (44,528 dollars) for patients with genotype 1.

CONCLUSIONS

For patients with chronic hepatitis C, it is generally more cost effective to provide antiviral treatment at a mild rather than a moderate disease stage. For older patients (aged 65 years or over) with genotype 1, antiviral treatment at a mild stage is not cost effective.

Has demand outpaced supply for clinical trial participants?

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Background: Current estimates are less than 5% of adult cancer patients participate in clinical trials. Initiatives to address barriers to accrual (such as age, physician bias, etc) are ongoing. However, with more drugs in the pipeline and more clinical trials being conducted, demand for trial participants may be outpacing the current “supply”. Methods: The ClinicalTrials.gov database, maintained by National Institutes of Health was selected for review on the basis that it is proposed to be the mandated repository for clinical trials information. Over a 2 month period, the database was mined for all active, US recruiting, phase I, I/II, II, and III trials in breast, lung, and prostate cancers. Results: There were 290 breast, 212 lung, and 177 prostate cancer trials with the prespecified criteria. The number of patients needed to complete these trials is 151,311 (breast), 33,498 (lung), and 53,181 (prostate). These represent 19.4% to 71.6% of the American Cancer Society incidence estimates of the studied tumors. NCI, industry, and academia sponsored, either solely or in collaborations, 42.1%, 26.5%, and 45.6% of trials, respectively. Majority of studies were phase II (51%), with 11.5% phase I, and 15.6% phase III. Remaining studies were either combined phase I/II studies or not specified. Significant percentage of trials involved pts with advanced/metastatic disease (54% breast, 51.4% lung, and 44.6% prostate). Conclusions: Although many studies have anticipated enrollment period over several years, the number of trial participants needed to complete these studies is quite daunting. Our results are likely under-estimates as not all studies currently enrolling patients may be included in this registry, and not all studies in the database specified the recruitment goal. Although not all trial participants are drawn from the incidence numbers, it is clear that given the current trial participation rate, demand has outpaced the supply. The medical community has the ethical responsibility to ensure sufficient patient enrollment for clinical trials. In addition to addressing accrual barriers, the authors encourage the establishment of a task force including academia, government, and industry to systematically evaluate and prioritize the types of trials being conducted.

No significant financial relationships to disclose.

Gemcitabine and oxaliplatin followed by paclitaxel and carboplatin as first line therapy for patients with suboptimally debulked, advanced epithelial ovarian cancer. A phase II trial of sequential doublets. The GO-First Study

OBJECTIVES

Gemcitabine and oxaliplatin are active in epithelial ovarian cancer with minimal overlapping toxicity. We studied the efficacy and toxicity of this combination in patients with advanced ovarian cancer when given prior to carboplatin and paclitaxel.

METHODS

Chemonaive patients with epithelial ovarian cancer and measurable disease were eligible for the study. Treatment consisted of gemcitabine 1250 mg/m2 on days 1 and 8 and oxaliplatin 130 mg/m2 on day 8 every 21 days (GO) for 4 cycles. This was followed by carboplatin AUC = 6 and paclitaxel 175 mg/m2 on day 1 every 21 days (CP) for 4 cycles.

RESULTS

Twenty patients, median age 62 years (range 39-78), FIGO stages III (16) and IV (4) received treatment. The response rate (RR) after 4 cycles of GO was 80% (95%CI 61-99%) (4 complete responses (CR), 12 partial responses (PR)). Interval debulking surgery was performed in 7 patients (35%). After CP chemotherapy, RR increased to 85% (95%CI 68-100%) (CR = 13, PR = 4). Median time to progression was 14.5 months. Estimated median overall survival was 31.5 months. Toxicities of GO were mild; grade 3/4 nausea in 3 patients (15%) and vomiting in 2 patients (10%), grade 3/4 neutropenia in 5 patients (25%). Grade 2/3 peripheral neuropathy occurred in 5 patients (25%). After sequential administration of CP, grade 2/3 neuropathy occurred in 13 patients (72%).

CONCLUSION

The sequential doublet regimen of GO followed by CP resulted in unacceptable neurotoxicity and is not recommended for further study; however, the doublet gemcitabine and oxaliplatin has significant activity in the first line treatment of patients with ovarian cancer.

Clinical outcomes of neoadjuvant chemotherapy and primary debulking surgery in advanced ovarian carcinoma

BACKGROUND

Primary debulking surgery (PDS) and paclitaxel-platinum chemotherapy remains the mainstay of treatment for advanced ovarian cancer. However, there is considerable morbidity and even mortality associated with this approach. The concept of primary chemotherapy followed by interval debulking surgery (IDS) has emerged for advanced stage disease with the aim of improving sensitivity to chemotherapy and improving survival. The purpose of our study was to examine the impact of IDS on clinical outcomes of patients considered unsuitable for PDS and compare them with outcomes of women that had conventional PDS followed by chemotherapy.

PATIENTS AND METHODS

A non-randomised prospective cohort study of 35 patients who underwent IDS and 29 patients treated with PDS were included. All patients had Stage IIIC or IV disease. The IDS patients were considered unresectable based on an initial laparoscopy or preoperative computed tomography findings. All patients were treated by the same lead surgeons and received the same regimen of chemotherapy.

RESULTS

The median intraoperative blood loss, the incidence of pelvic lymphadenectomies, the median hospital stay and the possibility of admission to the Intensive Care Unit were significantly less in the IDS group. Optimal cytoreduction was higher in the IDS compared to the PDS group, but did not reach statistical significance.

CONCLUSIONS

IDS for advanced ovarian cancer may be associated with less morbidity compared to PDS and appears to require less use of hospital resources. If the ongoing randomised studies confirm that IDS does not adversely affect the long-term survival of these patients, morbidity related to ovarian cancer surgery may evolve as a crucial factor for choosing treatment options.

Degradation of 2,4,6-trinitrotoluene by selected helophytes

Four emergent plants (helophytes, synonyms emersion macrophytes, marsh plants, etc.) Phragmites australis, Juncus glaucus, Carex gracillis and Typha latifolia were successfully used for degradation of TNT (2,4,6-trinitrotoluene) under in vitro conditions. The plants took up and transformed more than 90% of TNT from the medium within ten days of cultivation. The most efficient species was Ph. australis which took up 98% of TNT within ten days. The first stable degradation products 4-amino-2,6-dinitrotoluene (4-ADNT) and 2-amino-4,6-dinitrotoluene (2-ADNT) were identified and analysed during the cultivation period. [14C] TNT was used for the detection of TNT degradation products and their compartmentalization in plant tissues after two weeks of cultivation. Forty one percent of 14C was detected as insoluble or bound in cell structures: 34% in roots and 8% in the aerial parts. These results open the perspective of using the above-mentioned plants for the remediation of TNT contaminated waters.

Immune responses in advanced colorectal cancer following repeated intradermal vaccination with the anti-CEA murine monoclonal antibody, PR1A3: results of a phase I study

BACKGROUND AND AIMS

The aim was to determine the toxicity, clinical and immune responses to the murine monoclonal anti-carcinoembryonic antigen (CEA) antibody, PR1A3, in patients with advanced colorectal cancer.

MATERIALS AND METHODS

Fifteen patients with advanced colorectal cancer received either 0.5-, 1.0- or 5.0-mg doses of PR1A3 mixed with 10% w/v Alum adjuvant (Superfos Biosector, Denmark) intradermally at 4-week intervals for 3 months. Patient serum was assessed for anti-idiotypic (Ab2), anti-anti-idiotypic (Ab3) and human anti-mouse antibody (HAMA) reactivity. Peripheral blood mononuclear cell (PBMC) proliferation with phytohaemagglutinin (PHA), CEA and PR1A3, stimulated IL-2, IL-4 and IFN-gamma levels and PR1A3-stimulated IL-2 receptor expression during immunotherapy were determined. Comparisons were made with 16 age-matched controls without malignant disease.

RESULTS

Hyperimmune sera from 12 of the 15 patients showed Ab2 reactivity with no detectable Ab3 responses. Strong HAMA reactivity was recorded in 7 of the 15 cases with no adverse clinical effect. Delayed-type hypersensitivity (DTH) responses developed in 12 of the 15 patients. Pre-treatment PBMC proliferation with PHA was subnormal in each patient compared with controls, becoming normal (or supranormal) in all patients during immunisation (P<0.001). PBMC proliferation with CEA and PR1A3 increased during immunotherapy (P<0.001) along with stimulated production of IL-2, IFN-gamma and IL-2 receptor expression. Progressive disease was observed in 14 of the 15 patients with minimal toxicity.

CONCLUSION

PR1A3 generated limited idiotypic responses but robust DTH reactivity in most patients. In vitro PBMC proliferation with mitogens and recall antigens is greatly increased during the course of immunisation, with a shift in stimulated cytokine profile.