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S P Robinson

Publications and source records attributed to S P Robinson.

At least 19 recordsLinked to original sources
PubMed2005

Early emergence of PNH-like T cells after allogeneic stem cell transplants utilising CAMPATH-1H for T cell depletion.

CAMPATH-1H (C-1H) is widely used in vivo and / or in vitro for T cell depletion in hematopoietic SCT. This humanised monoclonal antibody is specific for CD52, a marker coexpressed on the majority of human lymphocytes with CD48 and other glycosylphosphatidyl-inositol (GPI) anchored proteins. We detected CD52 / CD48 dual expression on >99% of CD3(+) lymphocytes from normal individuals and all 15 post-SCT patients whose transplants did not utilise C-1H. By contrast, 23 / 26 patients with transplants involving C-1H (in vivo, in vitro or both) exhibited populations lacking CD52 expression that accounted for 49.7% (4.2-86.2%) of the CD3+ lymphocytes (median and range) in samples evaluated at a median of 2 months post-SCT. Most CD52- cells also lacked CD48 expression. These GPI- T cells were of either donor or mixed donor / recipient origin. They were predominant in the early months after SCT at times of profound lymphopenia and inversely correlated with the recovery of the absolute lymphocyte count (r= - 0.663, P<0.0001). The presence of CD52- cells has been correlated previously with clinical outcome after CAMPATH therapy for both malignant and nonmalignant diseases.

Adolescent↗
PubMed2004

The C-neu mammary carcinoma in Oncomice; characterization and monitoring response to treatment with herceptin by magnetic resonance methods.

To characterize spontaneously occurring c-neu/HER2 overexpressing tumours in oncomice and their response to herceptin by non-invasive magnetic resonance spectroscopy (MRS) and magnetic resonance imaging (MRI). Oncomice were monitored by localized 31P MRS during unperturbed growth and before and after treatment with 10 mg/kg herceptin (Hoffman La Roche) intraperitoneally for up to 21 days post-treatment. Vascular morphology and function was assessed by quantitation of tumour magnetic resonance (MR) relaxation rates R2* and R2 prior to and either during carbogen (95% O2/5% CO2) breathing or following administration of the blood-pool contrast agent NC100150 (Clariscan, Amersham Health). Immunohistochemistry showed strong membrane staining for HER2 protein overexpression. The 31P MRS showed only a significant (p<0.01) increase of phosphomonoester / total phosphate ratio over 21 days of growth. Herceptin increased the tumour volume doubling time compared to untreated tumours and significantly increased the phosphomonoester / beta-nucleoside triphosphate ratio 2 days after treatment (p=0.01). Tumours showed a highly heterogeneous yet significant (p<0.01) decrease or increase in R2* in response to carbogen or NC100150 respectively. The absence of a decline in tumour bioenergetics with growth, commonly seen in 31P MRS studies of transplanted rodent tumour models, coupled with the heterogeneous blood volume revealed by 1H MRI, suggest a metabolic and vascular phenotype similar to that found in human tumours.

Animals↗
PubMed2004

Investigations in vivo of the effects of carbogen breathing on 5-fluorouracil pharmacokinetics and physiology of solid rodent tumours.

PURPOSE: We have shown previously that carbogen (95% 0(2), 5% CO(2)) breathing by rodents can increase uptake of anticancer drugs into tumours. The aim of this study was to extend these observations to other rodent models using the anticancer drug 5-fluorouracil (5FU). 5FU pharmacokinetics in tumour and plasma and physiological effects on the tumour by carbogen were investigated to determine the locus of carbogen action on augmenting tumour uptake of 5FU. METHODS: Two different tumour models were used, rat GH3 prolactinomas xenografted s.c. into nude mice and rat H9618a hepatomas grown s.c. in syngeneic Buffalo rats. Uptake and metabolism of 5FU in both tumour models with or without host carbogen breathing was studied non-invasively using fluorine-19 magnetic resonance spectroscopy ((19)F-MRS), while plasma samples from Buffalo rats were used to construct a NONMEM pharmacokinetic model. Physiological effects of carbogen on tumours were studied using (31)P-MRS for energy status (NTP/Pi) and pH, and gradient-recalled echo magnetic resonance imaging (GRE-MRI) for blood flow and oxygenation. RESULTS: In both tumour models, carbogan-induced GRE-MRI signal intensity increases of approximately 60% consistent with an increase in tumour blood oxygenation and/or flow. In GH3 xenografts, (19)F-MRS showed that carbogen had no significant effect on 5FU uptake and metabolism by the tumours, and (31)P-MRS showed there was no change in the NTP/Pi ratio. In H9618a hepatomas, (19)F-MRS showed that carbogen had no effect on tumour 5FU uptake but significantly ( p=0.0003) increased 5FU elimination from the tumour (i.e. decreased the t(1/2)) and significantly ( p=0.029) increased (53%) the rate of metabolism to cytotoxic fluoronucleotides (FNuct). The pharmacokinetic analysis showed that carbogen increased the rate of tumour uptake of 5FU from the plasma but also increased the rate of removal. (31)P-MRS showed there were significant ( p<or=0.02) increases in the hepatoma NTP/Pi ratio of 49% and transmembrane pH gradient of 0.11 units. CONCLUSIONS: We suggest that carbogen can transiently increase tumour blood flow, but this effect alone may not increase uptake of anticancer drugs without a secondary mechanism operating. In the case of the hepatoma, the increase in tumour energy status and pH gradient may be sufficient to augment 5FU metabolism to cytotoxic FNuct, while in the GH3 xenografts this was not the case. Thus carbogen breathing does not universally lead to increased uptake of anticancer drugs.

Animals↗
PubMed2004

Granulocyte transfusions in the G-CSF era. Where do we stand?

The efficacy of granulocytes transfusions (GTX) in either the prevention or treatment of neutropenic sepsis has been a controversial issue. Early studies employing steroid mobilised GTX showed variable, dose-dependent results and significant pulmonary toxicity was reported. With the introduction of the recombinant myeloid growth factor, granulocyte-colony stimulating factor (G-CSF), the quantity of granulocytes that could be harvested was substantially increased leading to renewed interest in the clinical application of GTX. The administration of G-CSF to normal donors leads to significantly higher pre-harvest neutrophil counts and consequently larger granulocyte harvests. Infusion of G-CSF stimulated GTX results in measurable increases in the recipients' neutrophil count and may reduce the duration and severity of neutropenia. However, the efficacy of these GTX in treating or preventing established neutropenic sepsis remains to be established in prospective controlled clinical trials.

Granulocyte Colony-Stimulating Factor↗
PubMed2003

Tumour dose response to the antivascular agent ZD6126 assessed by magnetic resonance imaging.

ZD6126 is a vascular targeting agent that disrupts the tubulin cytoskeleton of proliferating neo-endothelial cells. This leads to the selective destruction and congestion of tumour blood vessels in experimental tumours, resulting in extensive haemorrhagic necrosis. In this study, the dose-dependent activity of ZD6126 in rat GH3 prolactinomas and murine RIF-1 fibrosarcomas was assessed using two magnetic resonance imaging (MRI) methods. Dynamic contrast-enhanced (DCE) MRI, quantified by an initial area under the time-concentration product curve (IAUC) method, gives values related to tumour perfusion and vascular permeability. Multigradient recalled echo MRI measures the transverse relaxation rate T(2)*, which is sensitive to tissue (deoxyhaemoglobin). Tumour IAUC and R(2)* (=1/T(2)*) decreased post-treatment with ZD6126 in a dose-dependent manner. In the rat model, lower doses of ZD6126 reduced the IAUC close to zero within restricted areas of the tumour, typically in the centre, while the highest dose reduced the IAUC to zero over the majority of the tumour. A decrease in both MRI end points was associated with the induction of massive central tumour necrosis measured histologically, which increased in a dose-dependent manner. Magnetic resonance imaging may be of value in evaluation of the acute clinical effects of ZD6126 in solid tumours. In particular, measurement of IAUC by DCE MRI should provide an unambiguous measure of biological activity of antivascular therapies for clinical trial.

Animals↗
PubMed2002

Dimethylarginine dimethylaminohydrolase I enhances tumour growth and angiogenesis.

Angiogenesis is a prerequisite for tumour progression and is highly regulated by growth factors and cytokines a number of which also stimulate the production of nitric oxide. Asymmetric dimethylarginine is an endogenous inhibitor of nitric oxide synthesis. Asymmetric dimethylarginine is metabolised by dimethylarginine dimethylaminohydrolase. To study the effect of dimethylarginine dimethylaminohydrolase on tumour growth and vascular development, the rat C6 glioma cell line was manipulated to overexpress the rat gene for dimethylarginine dimethylaminohydrolase I. Enhanced expression of dimethylarginine dimethylaminohydrolase I increased nitric oxide synthesis (as indicated by a two-fold increase in the production of cGMP), expression and secretion of vascular endothelial cell growth factor, and induced angiogenesis in vitro. Tumours derived from these cells grew more rapidly in vivo than cells with normal dimethylarginine dimethylaminohydrolase I expression. Immunohistochemical and magnetic resonance imaging measurements were consistent with increased tumour vascular development. Furthermore, dimethylarginine dimethylaminohydrolase activity was detected in a series of human tumours. This data demonstrates that dimethylarginine dimethylaminohydrolase plays a pivotal role in tumour growth and the development of the tumour vasculature by regulating the concentration of nitric oxide and altering vascular endothelial cell growth factor production.

Amidohydrolases↗
PubMed2001

Molecular cloning and characterisation of banana fruit polyphenol oxidase.

Polyphenol oxidase (PPO; EC 1.10.3.2) is the enzyme thought to be responsible for browning in banana [Musa cavendishii (AAA group, Cavendish subgroup) cv. Williams] fruit. Banana flesh was high in PPO activity throughout growth and ripening. Peel showed high levels of activity early in development but activity declined until ripening started and then remained constant. PPO activity in fruit was not substantially induced after wounding or treatment with 5-methyl jasmonate. Banana flowers and unexpanded leaf roll had high PPO activities with lower activities observed in mature leaves, roots and stem. Four different PPO cDNA clones were amplified from banana fruit (BPO1, BPO11, BPO34 and BPO35). Full-length cDNA and genomic clones were isolated for the most abundant sequence (BPO1) and the genomic clone was found to contain an 85-bp intron. Introns have not been previously found in PPO genes. Northern analysis revealed the presence of BPO1 mRNA in banana flesh early in development but little BPO1 mRNA was detected at the same stage in banana peel. BPO11 transcript was only detected in very young flesh and there was no detectable expression of BPO34 or BPO35 in developing fruit samples. PPO transcripts were also low throughout ripening in both flesh and peel. BPO1 transcripts were readily detected in flowers, stem, roots and leaf roll samples but were not detected in mature leaves. BPO11 showed a similar pattern of expression to BPO1 in these tissues but transcript levels were much lower. BPO34 and BPO35 mRNAs were only detected at a low level in flowers and roots and BPO34 transcript was detected in mature leaves, the only clone to do so. The results suggest that browning of banana fruit during ripening results from release of pre-existing PPO enzyme, which is synthesised very early in fruit development.

Acetates↗
PubMed2001

Expression patterns of cell wall-modifying enzymes during grape berry development.

During ripening of grape (Vitis vinifera L.) berries, softening occurs concomitantly with the second growth phase of the fruit and involves significant changes in the properties of cell wall polysaccharides. Here, the activities of enzymes that might participate in cell wall modification have been monitored throughout berry development. Alpha-galactosidase (EC 3.2.1.22), beta-galactosidase (EC 3.2.1.23) and pectin methylesterase (EC 3.1.1.11) activities were present, but no polygalacturonase (EC 3.2.1.15), cellulase (EC 3.2.1.4), xyloglucanase (xyloglucan-specific cellulase EC 3.2.1.4) or galactanase (EC 3.2.1.89) could be detected. The accumulation of mRNAs encoding wall-modifying enzymes was examined by northern hybridization analysis. Transcripts for beta-galactosidase, pectin methylesterase, polygalacturonase, pectate lyase (EC 4.2.2.2) and xyloglucan endotransglycosylase (EC 2.4.1.207) were present during ripening, although polygalacturonase activity had not been detected in berry extracts. Cellulases could not be detected in ripening berries, either at the enzyme or mRNA levels. The increase in beta-galactosidase activity and mRNA is consistent with the observed decrease in type-I arabinogalactan content of the walls during ripening, and the detection of polygalacturonase and pectate lyase mRNAs might explain the increased solubility of galacturonan in walls of ripening grapes. Thus, the modification of cell wall polysaccharides during softening of grape berries is a complex process involving subtle changes to different components of the wall, and in many cases only small amounts of enzyme activity are required to effect these changes.

Blotting, Northern↗
PubMed2001

Effects of different levels of hypercapnic hyperoxia on tumour R(2)* and arterial blood gases.

The hypercapnia induced by carbogen (95% O(2)/5% CO(2)) breathing, which is being re-evaluated as a clinical radiosensitiser, causes patient discomfort and hence poor compliance. Recent preclinical and clinical studies have indicated that the CO(2) content might be lowered without compromising increased tumour oxygenation and radiosensitisation. This preclinical study was designed to see if lower levels of hypercapnia could evoke similar decreases in the transverse relaxation rate R(2)* of rodent tumours to those seen with carbogen breathing. The response of rat GH3 prolactinomas to 1%, 212% and 5% CO(2) in oxygen, and 100% O(2) breathing, was monitored by non-invasive multi-gradient echo MRI to quantify R(2)*. As the oxygenation of haemoglobin is proportional to the blood p(a)O(2) and therefore in equilibrium with tissue pO(2), R(2)* is a sensitive indicator of tissue oxygenation. Hyperoxia alone decreased R(2)* by 13%, whilst all three hypercapnic hyperoxic gases decreased R(2)* by 29%. Breathing 1% CO(2) in oxygen evoked the same decrease in R(2)* as carbogen. The DeltaR(2)* response is primarily consistent with an increase in blood oxygenation, though localised increases in tumour blood flow were also identified in response to hypercapnia. The data support the concept that levels of hypercapnia can be reduced without loss of enhanced oxygenation and hence potential radiotherapeutic benefit.

Animals↗
PubMed2001

Response of Tradescantia albiflora to growth irradiance: Change versus changeability.

Most chloroplasts undergo changes in composition, function and structure in response to growth irradiance. However, Tradescantia albiflora, a facultative shade plant, is unable to modulate its light-harvesting components and has the same Chl a/Chl b ratios and number of functional PS II and PS I reaction centres on a Chl basis at all growth irradiances. With increasing growth irradiance, Tradescantia leaves have the same relative amount of chlorophyll-proteins of PS II and PS I, but increased xanthophyll cycle components and more zeaxanthin formation under high light. Despite high-light leaves having enhanced xanthophyll cycle content, all Tradescantia leaves acclimated to varying growth irradiances have similar non-photochemical quenching. These data strongly suggest that not all of the zeaxanthin formed under high light is necessarily non-covalently bound to major and minor light-harvesting proteins of both photosystems, but free zeaxanthin may be associated with LHC II and LHC I or located in the lipid bilayer. Under the unusual circumstances in light-acclimated Tradescantia where the numbers of functional PS II and PS I reaction centres and their antenna size are unaltered during growth under different irradiances, the extents of PS II photoinactivation by high irradiances are comparable. This is due to the extent of PS II photoinactivation being a light dosage effect that depends on the input (photon exposure, antenna size) and output (photosynthetic capacity, non-radiative dissipation) parameters, which in Tradescantia are not greatly varied by changes in growth irradiance.

Journal Article↗
PubMed2001

Construct design for efficient, effective and high-throughput gene silencing in plants.

Post-transcriptional silencing of plant genes using anti-sense or co-suppression constructs usually results in only a modest proportion of silenced individuals. Recent work has demonstrated the potential for constructs encoding self-complementary 'hairpin' RNA (hpRNA) to efficiently silence genes. In this study we examine design rules for efficient gene silencing, in terms of both the proportion of independent transgenic plants showing silencing, and the degree of silencing. Using hpRNA constructs containing sense/anti-sense arms ranging from 98 to 853 nt gave efficient silencing in a wide range of plant species, and inclusion of an intron in these constructs had a consistently enhancing effect. Intron-containing constructs (ihpRNA) generally gave 90-100% of independent transgenic plants showing silencing. The degree of silencing with these constructs was much greater than that obtained using either co-suppression or anti-sense constructs. We have made a generic vector, pHANNIBAL, that allows a simple, single PCR product from a gene of interest to be easily converted into a highly effective ihpRNA silencing construct. We have also created a high-throughput vector, pHELLSGATE, that should facilitate the cloning of gene libraries or large numbers of defined genes, such as those in EST collections, using an in vitro recombinase system. This system may facilitate the large-scale determination and discovery of plant gene functions in the same way as RNAi is being used to examine gene function in Caenorhabditis elegans.

Arabidopsis↗
PubMed2000

Characterization of polyphenol oxidase in coffee.

Polyphenol oxidase (PPO) was characterized in partially purified extracts of leaves (PPO-L) and fruit endosperm (PPO-E) of coffee (Coffea arabica L.). PPO activity was higher in early developmental stages of both leaves and endosperm of fruits. Wounding or exposure of coffee leaves to methyl jasmonate increased PPO activity 1.5-4-fold. PPO was not latent and was not activated by protease treatment. PPO activity was stimulated 10-15% with sodium dodecyl sulphate (SDS) at 0.35-1.75 mM, but at higher concentrations activities were similar to the control samples, without detergent. Prolonged incubation of extracts with trypsin or proteinase K inhibited PPO activity but pepsin had no effect. Inhibition of PPO with proteinase K was increased in the presence of SDS. PPO activity from both tissues was optimal at pH 6-7 and at an assay temperature of 30 degrees C. Activity was highest with chlorogenic acid as substrate with a Km of 0.882 mM (PPO-L) and 2.27 mM (PPO-E). Hexadecyl trimethyl-ammonium bromide, polyvinylpyrrolidone 40. cinnamic acid and salicylhydroxamic acid inhibited PPO from both tissues. Both enzymes were inactivated by heat but the activity in endosperm extracts was more heat labile than that from leaves. The apparent Mr determined by gel filtration was 46 (PPO-L) and 50 kDa (PPO-E). Activity-stained SDS polyacrylamide gel electrophoresis (PAGE) gels and western blots probed with PPO antibodies suggested the existence of a 67 kDa PPO which is susceptible to proteolytic cleavage that generates a 45 kDa active form.

Catechol Oxidase↗
PubMed2000

Effects of nicotinamide and carbogen on tumour oxygenation, blood flow, energetics and blood glucose levels.

Both host carbogen (95% oxygen/5% carbon dioxide) breathing and nicotinamide administration enhance tumour radiotherapeutic response and are being re-evaluated in the clinic. Non-invasive magnetic resonance imaging (MRI) and 31P magnetic resonance spectroscopy (MRS) methods have been used to give information on the effects of nicotinamide alone and in combination with host carbogen breathing on transplanted rat GH3 prolactinomas. Gradient recalled echo (GRE) MRI, sensitive to blood oxygenation changes, and spin echo (SE) MRI, sensitive to perfusion/flow, showed large signal intensity increases with carbogen breathing. Nicotinamide, thought to act by suppressing the transient closure of small blood vessels that cause intermittent tumour hypoxia, induced a small increase in blood oxygenation but no detectable change in perfusion/flow. Carbogen combined with nicotinamide was no more effective than carbogen alone. Both carbogen and nicotinamide caused significant increases in the nucleoside triphosphate/inorganic phosphate (betaNTP/Pi) ratio, implying that the tumour cells normally receive sub-optimal substrate supply, and is consistent with either increased glycolysis and/or a switch to more oxidative metabolism. The most striking observation was the marked increase in blood glucose (twofold) induced by both nicotinamide and carbogen. Whether this may play a role in tumour radiosensitivity has yet to be determined.

Animals↗
PubMed2000

Differential screening indicates a dramatic change in mRNA profiles during grape berry ripening. Cloning and characterization of cDNAs encoding putative cell wall and stress response proteins.

We used differential screening to isolate ripening-associated cDNAs from a Shiraz grape (Vitis vinifera L.) berry cDNA library. A rapid increase in the mRNA levels of a number of cDNAs not present in unripe fruit occurred in grape berries at the onset of ripening. The putative translation products of some of these clones had homologs in other species that are involved in cell wall structure. These included four proline-rich proteins, a small protein that is similar to the non-catalytic, N-terminal domain of some pectin methylesterases, and two other glutamate-rich proteins. The remainder of the clones encoded putative stress response proteins. These included two thaumatin-like proteins, a metallothionein, a transcription factor, a cytochrome P450 enzyme, and proteins induced by water, sugar, and/or cold stress in other species. Many of the homologs of the grape cDNAs thought to be involved in cell wall structure or stress-related responses also accumulate in a developmental manner in other plants. This may indicate that the grape mRNAs accumulate in response to stresses such as the storage of high concentrations of sugars and rapid cell expansion, or they may accumulate as part of the ripening developmental program.

Amino Acid Sequence↗
PubMed1999

Combined effect of platination and intercalation upon DNA binding of novel cytotoxic Pt-bis(naphthalimide) complexes.

The reaction of platinum salts with bis(naphthalimide), compound 1, yielded two Pt-bis(naphthalimide) complexes, compounds 2 and 3 which differ from each other in their leaving groups being 1,1-cyclobutane dicarboxylate or chloride, respectively. The testing of the cytotoxic activity of compounds 2 and 3 against several tumor cell lines indicated that both compounds may be endowed with important antineoplastic properties since they circumvent cisplatin resistance. At similar rates of DNA platination (r(b) = 0.025), compounds 2 and 3 unwind supercoiled pUC8 DNA by (48 +/- 2) degrees. Altogether, these data suggest (i) that the cytotoxic activity of compounds 2 and 3 may be due to a combined effect of platination and intercalation and (ii) that the bis(naphthalimide) ligand is a suitable "carrier" that favors DNA targeting by cis-Pt(II) centers.

1-Naphthylamine↗
PubMed1999

Tumour response to hypercapnia and hyperoxia monitored by FLOOD magnetic resonance imaging.

Flow and oxygenation dependent (FLOOD) MR images of GH3 prolactinomas display large intensity increases in response to carbogen (5% CO2/95% O2) breathing. To assess the relative contributions of carbon dioxide and oxygen to this response and the tumour oxygenation state, the response of GH3 prolactinomas to 5% CO2/95% air, carbogen and 100% O2 was monitored by FLOOD MRI and PO2 histography. A 10-30% image intensity increase was observed during 5% CO2/95% air breathing, consistent with an increase in tumour blood flow, as a result of CO2-induced vasodilation, reducing the concentration of deoxyhaemoglobin in the blood. Carbogen caused a further 40-50% signal enhancement, suggesting an additional improvement due to increase blood oxygenation. A small 5-10% increase was observed in response to 100% O2, highlighting the dominance of CO2-induced vasodilation in the carbogen response. Despite the large FLOOD response, non-significant increases in tumour pO2 were observed in response to the three gases. Tissue pO2 is determined by the balance of oxygen supply and demand, hence increased blood flow/oxygenation may not necessarily produce a large increase in tissue PO2. The FLOOD response is determined by the level of deoxygenation of blood, the size of this response relating to vascular density and the potential of high-oxygen content gases to improve the oxygen supply to tumour tissue.

Animals↗