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J E Painter

Publications and source records attributed to J E Painter.

7 recordsLinked to original sources
PubMed2001

High-risk colorectal adenomas and serum insulin-like growth factors.

BACKGROUND: This study investigated the hypothesis that circulating levels of insulin-like growth factor (IGF) I and its main binding protein (IGFBP-3) predict for the presence of colorectal adenomas, surrogate markers of colorectal cancer risk. METHODS: Within the Flexi-Scope Trial (healthy volunteers aged 55-64 years), at one study centre, IGF-I and IGFBP-3 levels in serum samples collected prospectively from 442 attendants were measured. Of these, 100 individuals underwent a complete screening colonoscopy. There were 47 normal examinations, while in 11 examinations low-risk adenomas and in 42 examinations high-risk adenomas were identified. Estimates of relative risk (RR) for the adenomatous stages were calculated by means of unconditional logistic regression, adjusting for known risk factors. RESULTS: Mean serum IGF-I and IGFBP-3 levels were similar in individuals with a normal colonoscopy finding and in those with low-risk adenomas. By contrast, the mean(s.d.) serum IGF-I level was increased (190(53) versus 169(54) microg/l; P = 0.06) and the serum IGFBP-3 concentration was significantly decreased (3.22(0.60) versus 3.47(0.62) mg/l; P = 0.05) in individuals with high-risk adenomas compared with levels in those with normal colonoscopy and low-risk adenomas combined. Levels were unaffected by removal of the adenomas. With high-risk adenoma as the dependent factor, regression models demonstrated a significant positive association with IGF-I after controlling for IGFBP-3 (RR per one standard deviation (1s.d.) change 4.39 (95 per cent confidence interval (c.i.) 1.31-14.7); P = 0.02) and, independently, an inverse association with IGFBP-3 after adjustment for IGF-I (RR per 1s.d. change 0.41 (95 per cent c.i. 0. 20-0.82); P = 0.01). CONCLUSION: These findings suggest that circulating IGF-I and IGFBP-3 levels are related to future colorectal cancer risk and, specifically, may predict adenoma progression.

Adenoma↗
PubMed2000

Integrated temporal regulation of the photorespiratory pathway. Circadian regulation of two Arabidopsis genes encoding serine hydroxymethyltransferase.

The photorespiratory pathway is comprised of enzymes localized within three distinct cellular compartments: chloroplasts, peroxisomes, and mitochondria. Photorespiratory enzymes are encoded by nuclear genes, translated in the cytosol, and targeted into these distinct subcellular compartments. One likely means by which to regulate the expression of the genes encoding photorespiratory enzymes is coordinated temporal control. We have previously shown in Arabidopsis that a circadian clock regulates the expression of the nuclear genes encoding both chloroplastic (Rubisco small subunit and Rubisco activase) and peroxisomal (catalase) components of the photorespiratory pathway. To determine whether a circadian clock also regulates the expression of genes encoding mitochondrial components of the photorespiratory pathway, we characterized a family of Arabidopsis serine hydroxymethyltransferase (SHM) genes. We examined mRNA accumulation for two of these family members, including one probable photorespiratory gene (SHM1) and a second gene expressed maximally in roots (SHM4), and show that both exhibit circadian oscillations in mRNA abundance that are in phase with those described for other photorespiratory genes. In addition, we show that SHM1 mRNA accumulates in light-grown seedlings, although this response is probably an indirect consequence of the induction of photosynthesis and photorespiration by illumination.

Amino Acid Sequence↗
PubMed2000

Circulating insulin-like growth factor II and colorectal adenomas.

Circulating insulin-like growth factor I (IGF-I) and IGF-binding protein-3 (IGFBP-3) may be risk factors for the development of colorectal cancer. On the other hand, IGF-II and IGFBP-2 are overexpressed in colorectal carcinomas. These contrasting backgrounds led us to investigate the relationship between serum IGF-I, IGF-II, IGFBP-2, and IGFBP-3 and the presence of colorectal adenomas, known precursors of colorectal carcinoma, in 345 volunteers attending a screening flexible sigmoidoscopy trial (entry criteria: healthy, aged 55-64 yr). The most striking finding was an elevated mean serum IGF-II in individuals with adenomas (n = 52) compared with controls (mean difference, 139 ng/mL; 95% confidence intervals, 82, 196; P < 0.0001). Logistic regression adjusting for confounding factors confirmed the significant association between IGF-II and adenoma occurrence (P < 0.0001) and revealed an additional positive association with serum IGFBP-2 (P < 0.0001). However, there was no association found between either serum IGF-I and/or IGFBP-3 and the presence of adenomas. Additionally, in 31 individuals with adenomas in whom levels were determined pre- and postpolypectomy, there was a significant fall in mean IGF-II (P < 0.001) and IGFBP-2 (P < 0.001) after adenoma removal, but no difference in IGF-II and IGFBP-2 concentrations between repeated samples in 20 individuals without adenomas. Immunohistochemical studies demonstrated IGF-II expression in 83% of all adenomas, which contrasted with absent expression in normal colonic expression and hyperplastic polyps. This study has shown for the first time that serum IGF-II may be a tumor marker in individuals with colorectal adenomas. Further studies are needed to validate these relationships in larger populations, including individuals undergoing colonoscopy.

Adenoma↗
PubMed2000

The prevalence and characteristics of colorectal neoplasia in acromegaly.

An increased prevalence of colorectal neoplasia has been reported in acromegalic patients, and recommendations have been made for early colonoscopic screening and regular surveillance. This assumption, however, is frequently drawn from studies using selected control populations. To clarify colonoscopic management in these patients, we undertook a 2-center prospective screening colonoscopy study in 122 acromegalics (age range, 25-82 yr). In the absence of ideal age-matched controls, we calculated prevalence rates of occult adenocarcinomas and adenomas in the general population using cumulative data in the published literature from 8 autopsy studies (model 1, n = 3,559) and 4 screening colonoscopy studies (model 2, n= 810), applying linear regression models. Of the 115 patients with complete examinations, adenocarcinomas were discovered in 3 (2.6%), and at least 1 adenoma was found in 11, giving an overall prevalence of neoplasia of 12% (14 of 115). Prevalence rates for age bands 30-40, 40-49, 50-59, 60-69, and 70+ yr were 0%, 8%, 12%, 20%, and 21%, respectively. Compared with the 2 control models, the prevalence of occult colorectal cancer was not significantly increased (acromegalics vs. models 1 and 2, 2.6% vs. 2.3% and 0.9%), nor was there an increase in the prevalence of adenomas in any age band. Pathological characteristics showed some differences, in that adenomas in acromegalics tended to be right sided (68% vs. 57% and 56%), larger (for > or =10 mm, 27% vs. 13% and 9%), and of advanced histology (for tubulovillous, 27% vs. 4% and 22%). No associations were found between the presence of colonic neoplasia and the duration of disease, total GH exposure, cure status, and serum insulin-like growth factor I. This study has failed to demonstrate an increased prevalence of neoplasia in acromegalic patients compared with the expected prevalence in the general population and questions the need for an aggressive colonoscopic screening policy.

Acromegaly↗
PubMed1998

Imbibition, but not release from stratification, sets the circadian clock in Arabidopsis seedlings.

Circadian rhythms in the abundance of the CAT2 catalase mRNA were not seen in etiolated seedlings but developed upon illumination. These circadian oscillations were preceded by a rapid and transient induction of CAT2 mRNA abundance that varied strikingly according to the timing (circadian phase) of the onset of illumination. This variation oscillated with a circadian periodicity of approximately 28 hr, indicating that the circadian oscillator is running in etiolated seedlings and regulates (gates) the induction of CAT2 by light. Moreover, because we assayed populations of seedlings, we infer that the individual clocks among populations of etiolated seedlings were synchronized before the onset of illumination. What developmental or environmental signals synchronized the clocks among seedlings? Varying the phase of the onset of illumination relative to release from stratification failed to affect the acute induction of CAT2, indicating that the temperature step from 4 to 22 degrees C associated with release from stratification did not reset the circadian clock. However, the acute induction of CAT2 mRNA varied with time after imbibition, demonstrating that imbibition provides a signal capable of resetting the circadian clock and of synchronizing the clocks among populations of seedlings.

Arabidopsis↗