Adaptive statistical iterative reconstruction improves image quality without affecting perfusion CT quantitation in primary colorectal cancer.

OBJECTIVES: To determine the effect of Adaptive Statistical Iterative Reconstruction (ASIR) on perfusion CT (pCT) parameter quantitation and image quality in primary colorectal cancer. METHODS: Prospective observational study. Following institutional review board approval and informed consent, 32 patients with colorectal adenocarcinoma underwent pCT (100 kV, 150 mA, 120 s acquisition, axial mode). Tumour regional blood flow (BF), blood volume (BV), mean transit time (MTT) and permeability surface area product (PS) were determined using identical regions-of-interests for ASIR percentages of 0%, 20%, 40%, 60%, 80% and 100%. Image noise, contrast-to-noise ratio (CNR) and pCT parameters were assessed across ASIR percentages. Coefficients of variation (CV), repeated measures analysis of variance (rANOVA) and Spearman' rank order correlation were performed with statistical significance at 5%. RESULTS: With increasing ASIR percentages, image noise decreased by 33% while CNR increased by 61%; peak tumour CNR was greater than 1.5 with 60% ASIR and above. Mean BF, BV, MTT and PS differed by less than 1.8%, 2.9%, 2.5% and 2.6% across ASIR percentages. CV were 4.9%, 4.2%, 3.3% and 7.9%; rANOVA P values: 0.85, 0.62, 0.02 and 0.81 respectively. CONCLUSIONS: ASIR improves image noise and CNR without altering pCT parameters substantially.

Normal variations in pancreatic contour are associated with intestinal malrotation and can mimic neoplasm.

AIM: To describe the frequency of normal variation in contour of the head and uncinate process of the pancreas in patients with intestinal malrotation, some of which can mimic neoplasm, and their relationship with mesenteric vascular inversion. METHODS: A retrospective analysis of 25 cases of intestinal malrotation on cross-sectional imaging [24 computed tomography (CT) examinations, one magnetic resonance imaging (MRI) examination], was performed by two specialist gastrointestinal radiologists. The presence and type of intestinal malrotation, variations in pancreatic contour, and the location of the superior mesenteric vessels were analysed. RESULTS: Twenty-five cases of malrotation (21 complete, four partial) with a median age of 50 years (range 17-91 years) were reviewed. Eighty-six percent (18/21) of complete malrotation cases demonstrated an unusual pancreatic contour. There was hypoplasia or aplasia of the uncinate process in 86% (18/21) of cases. Both uncinate process and pancreatic head contour anomalies were demonstrated in 57% (12/21) of cases, which included 24% (5/21) with a globular-shaped enlargement of the head of pancreas. Mesenteric vascular inversion was seen in 90% (19/21) of cases. One hundred percent (4/4) of partial malrotation cases had normal pancreatic and vascular anatomy. CONCLUSION: Pancreatic contour variations are common in malrotation and the enlargement of the pancreatic head in some cases can mimic a neoplasm. The embryological cause may be due to anomalous fusion of the ventral bud of the pancreas with the dorsal bud, explaining the common finding of a small uncinate process with a large pancreatic head.

Serum concentrations of myostatin and myostatin-interacting proteins do not differ between young and sarcopenic elderly men.

Sarcopenia is the loss of muscle size and function during ageing. The aim of this study was to test whether serum concentrations of myostatin and interacting proteins (GASP-1, FLRG, and follistatin) differed between young and elderly sarcopenic men. Isometric knee extensor maximal voluntary contraction and quadriceps cross-sectional area (magnetic resonance imaging measurement) were significantly higher in young (22 ± 2 years; 266 ± 54 N/m; 8,686 ± 1,154 mm(2)) than in mildly sarcopenic (69 ± 3 years; 183 ± 17 N/m; 6,621±718 mm(2)) and severely sarcopenic men (76 ± 6 years; 127 ± 23 N/m; 5,846 ± 591 mm(2)), respectively (p ≤ .01 for all comparisons). There was a trend (p = .06) toward higher FLRG in young (20 ± 8 ng/mL) than in mildly (15 ± 6 ng/mL) and severely sarcopenic men (17 ± 8 ng/mL). Myostatin, follistatin, GASP-1, tumor necrosis factor α, and interleukin-6 did not differ significantly. Insulin-like growth factor-1 and free testosterone were both significantly lower in sarcopenic men (p < .001). This suggests that altered serum concentrations of myostatin and myostatin-interacting proteins are not contributing to sarcopenia with the possible exception of FLRG.

Utility of combining MMP-9 enzyme-linked immunosorbent assay and MMP-9 activity assay data to monitor plasma enzyme specific activity.

The aim of this study was to combine matrix metalloproteinase-9 (MMP-9) protein (enzyme-linked immunosorbent assay [ELISA]) and MMP-9 activity (fluorescence resonance energy transfer [FRET] assay) data to generate units of specific activity in endogenous and p-aminophenylmercuric acetate (APMA)-activated lithium heparin plasma. The results indicate that specific activity is constant in APMA-activated plasma (mean value=1359.4 pmol/min/microg) and approximately 12% plasma MMP-9 is endogenously active. Exogenous tissue inhibitor of metalloproteinase-1 (TIMP-1) has a greater inhibitory effect on endogenously active MMP-9 than on APMA-activated MMP-9. In conclusion, specific activity can be used as a tool to monitor MMP-9 inhibition. APMA activation affects natural enzyme inhibition, possibly by chemical modification of the C-terminal portion of the enzyme containing the TIMP-1 binding site.

Multidetector CT appearances of splanchnic arterial pathology.

Recent advances in multidetector computed tomography (MDCT) technology have enabled the production of high-resolution diagnostic images of the visceral vessels. The potential of MDCT in relation to splanchnic artery pathology is still being realized, but it already provides a credible quick, non-invasive, low-dose alternative to digital subtraction angiography. A variety of categories of splanchnic artery pathology are demonstrated, including stenosis and occlusion (due to extrinsic compression, mural thrombus, and atherosclerosis), aneurysms, dissection, and haemorrhage.

Biolistic transformation of Arabidopsis root hairs: a novel technique to facilitate map-based cloning.

The final stage of map-based gene isolation is complementation of the mutant phenotype with wild-type DNA to determine the exact location of the gene of interest. This usually involves Agrobacterium tumefaciens-mediated transformation, which is reliable and produces stable transformants. However, the process of Agrobacterium transformation may take up to three months to complete. If the mutant phenotype can be seen in a single cell, and the wild-type copy of the gene can act cell autonomously, then complementation of the whole plant is not strictly necessary. We have developed a technique for the biolistic transformation of Arabidopsis thaliana root hairs, and used this to test large insert clones for complementation of two recessive mutant phenotypes, a procedure that takes less than a day. Our results show that biolistic transformation can be used with transient assays to conduct rapid tests for complementation by large insert clones.

Genetic interactions during root hair morphogenesis in Arabidopsis.

Root hairs are a major site for the uptake of water and nutrients into plants and form an increasingly important model system for studies of development of higher plants and cell biology. We have identified loss-of-function mutations in eight new genes required for hair growth in Arabidopsis: SHAVEN1 (SHV1), SHV2, and SHV3; CENTIPEDE1 (CEN1), CEN2, and CEN3; BRISTLED1 (BST1); and SUPERCENTIPEDE1 (SCN1). We combined mutations in 79 pairs of genes to determine the stages at which these and six previously known genes contribute to root hair formation. Double mutant phenotypes revealed roles for several genes that could not have been predicted from the single mutant phenotypes. For example, we show that TIP1 and RHD3 are required much earlier in hair formation than previous studies have suggested. We present a genetic model for root hair morphogenesis that defines the roles of each gene, and we suggest hypotheses about functional relationships between genes.

The COW1 locus of arabidopsis acts after RHD2, and in parallel with RHD3 and TIP1, to determine the shape, rate of elongation, and number of root hairs produced from each site of hair formation.

Two recessive mutant alleles at CAN OF WORMS1 (COW1), a new locus involved in root hair morphogenesis, have been identified in Arabidopsis thaliana L. Heynh. Root hairs on Cow1- mutants are short and wide and occasionally formed as pairs at a single site of hair formation. The COW1 locus maps to chromosome 4. Root hairs on Cow1- plants form in the usual positions, suggesting that the phenotype is not the result of abnormal positional signals. Root hairs on Cow1- roots begin hair formation normally, forming a small bulge, or root hair initiation site, of normal size and shape and in the usual position on the hair-forming cell. However, when Cow1- root hairs start to elongate by tip growth, abnormalities in the shape and elongation rate of the hairs become apparent. Genetic evidence from double-mutant analysis of cow1-1 and other loci involved in root hair development supports our conclusion that COW1 is required during root hair elongation.

Separate cis sequences and trans factors direct metabolic and developmental regulation of a potato tuber storage protein gene.

The expression of genes encoding patatin, a major tuber protein, is highly tissue-specific but is also modulated by exogenous sucrose. The patterns of transcription observed in potato plants could be due to mechanisms conferring tuber-specificity or they could reflect the concentrations of sucrose found in different tissues. To distinguish between these possibilities, a detailed examination was made of the function of a region of the promoter previously implicated in conferring tissue-specific and sucrose-inducible expression. Internal deletions of this region revealed three separate functional domains regulating expression. The B repeat region acted as a positive activator of transcription in the tuber and was also responsible for a degree of sucrose-inducibility. The distal region of the A repeat repressed transcription in leaf and tuber tissue, while the proximal region of the A repeat was able to confer sucrose-responsiveness. Each of these regions specifically bound nuclear proteins which may be putative transcription factors involved in conferring these responses. The region found to confer sucrose-inducible expression was conserved among some other genes that are also regulated by exogenous sucrose.

Transcriptional control of plant storage protein genes.

The accumulation of plant storage proteins is controlled primarily by the transcriptional activation of their genes. Two classes of storage proteins, the zygotic or seed-specific, and the somatic, such as tuber proteins, have been studied. Gene expression analysis in transgenic plants has defined small regions of the promoters of such genes that are able to confer the appropriate patterns of expression. Protein-DNA interactions, both in vivo and in vitro, have revealed proteins that bind to regions implicated in expression, and these may be transcription factors. Promoter deletion analysis has determined the role of some of these DNA-binding proteins, such as in determining tissue-specificity or levels of expression. A common theme linking the expression of both classes of storage proteins is the involvement of metabolite levels in directly controlling gene expression.

DNA-binding properties of cloned TATA-binding protein from potato tubers.

A full-length cDNA clone encoding the TATA-binding protein (TBP), the DNA-binding component of the general transcription factor TFIID was cloned from potato tubers. The DNA sequence of this cDNA indicated that the predicted potato protein was very similar to cloned TBP from other species. Genomic southern analysis showed that TBP is encoded in the potato genome as a low-copy-number sequence. The potato TBP cDNA clone was shown to encode a functional protein that interacts in a sequence-specific way with the promoter region of a class-1 potato patatin gene. Functional analysis of carboxy-terminal truncated derivatives of potato TBP showed that important components of DNA binding were located within the carboxy-terminal 54 amino acids. Kinetic and thermodynamic properties of in vitro synthesised potato TBP were investigated, and demonstrated strict salt and temperature preferences for maximum DNA binding activity. In addition on and off-rate measurements showed that both association and dissociation of TBP from DNA is slow. The specific and the non-specific equilibrium constants Ks and Kn were calculated as 5 x 10(9) M-1 and 3.65 x 10(4) M-1 respectively. These results indicate that the interaction of potato TBP with the patatin promoter is highly specific.

Drinking behaviour in sea water and fresh water teleosts, the role of the renin-angiotensin system.

Basal drinking rate and responses to administered angiotensin were examined in 12 species of fish. The responses of representative euryhaline, stenohaline marine and fresh water species to pharmacological manipulation of endogenous renin-angiotensin system (RAS) activity were also investigated.Basal drinking rates were consistently low in stenohaline and euryhaline fresh water fish, and all species examined showed an increased imbibition in response to administered angiotensin. Marine fish drank large volumes of water, rates varying considerably between species, with euryhaline species exhibiting lower rates than stenohaline groups. The extremely high drinking rates observed in the sea scorpion were associated with a high plasma osmolality. With the exception of the sea scorpion, all other species examined in sea water showed a further rise in drinking in response to exogenous angiotensin.Although the freshwater stenohaline carp showed a dipsogenic response to angiotensin, it was apparently unable to evoke this response when fish were acclimated to brackish water. The high drinking rates of both euryhaline and stenohaline fish held in sea water appeared dependent upon an activated endogenous RAS, and were lowered following inhibition of Al to All conversion by Captopril. Drinking was further stimulated in these marine species following stimulation of endogenous RAS activity by the administration of the hypotensive agent Papaverine. The study endorses a role for the RAS in the control of adaptive drinking in euryhaline and stenohaline marine teleosts.

Circulatory and ionoregulatory effects of atrial natriuretic peptide on rainbow trout (Salmo gairdneri Richardson) fed normal or high levels of dietary salt.

Rainbow trout fed a normal salt diet (1.3% NaCl) or a high salt diet (12% NaCl for at least 6 months) were chronically cannulated in the dorsal aorta and received 10 µg kg(-1) ANP (1-28 human, UBC-Bioproducts) infused over a 10 min period. This had an insignificant influence on sodium balance, blood electrolytes and branchial sodium fluxes. In fish given a normal diet, the blood pressure and heart rate were uninfluenced by ANP, but pulse pressure was reduced by on average 60% and in some cases was not evident at all. Blood pressure in the fish fed a high salt diet was significantly higher than in the control fish; this together with heart rate and pulse pressure was not affected by ANP administration.

Immunization against Nippostrongylus brasiliensis in the rat. A study on the use of antigen extracted from adult parasites and the parameters which influence the level of protection.

It was found that protective immunity in excess of 90% reduction in worm burden could be stimulated against Nippostrongylus brasiliensis in rats by using an extract of adult Nippostrongylus worms. The level of protection achieved was influenced by several factors. Thus, the use of Bordetella pertussis as adjuvant significantly increased the level of protection which, in addition, was shown to be influenced by the amount of worm antigen used. Furthermore, antigen administered in multiple doses was more effective than a single inoculum and, when using such a regime, the interval between doses was also found to be critical. The route of antigen administration was important and, while protection was achieved by subcutaneous and oral administration, the intraperitoneal route was the most effective. Using the optimal immunization regime of 3 doses of 5 mg worm protein and 4 x 10(10( B. pertussis organisms, as adjuvant, levels of protective immunity in excess of 90% reduction in worm burden were shown to exist for at least 60 days after the last dose. It was found that adult worm extracts did not stimulate any obvious immunity against larval forms of N. brasiliensis.