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R J Kennedy

Publications and source records attributed to R J Kennedy.

At least 19 recordsLinked to original sources
PubMed2003

First-order transition from a Kondo insulator to a ferromagnetic metal in single crystalline FeSi(1-x)Ge(x).

The phase diagram of FeSi(1-x)Ge(x), obtained from magnetic, thermal, and transport measurements on single crystals, shows a discontinuous transition from Kondo insulator to ferromagnetic metal with x at a critical concentration, x(c) approximately 0.25. The gap of the insulating phase strongly decreases with x. The specific heat gamma coefficient appears to track the density of states of a Kondo insulator. The phase diagram is consistent with an insulator-metal transition induced by a reduction of the hybridization with x in conjunction with disorder on the Si/Ge ligand site.

Journal Article↗
PubMed2003

Removal of two sentinel nodes accurately stages the axilla in breast cancer.

BACKGROUND: Assessment of lymph node status in breast cancer is still necessary for staging. Sentinel lymph node biopsy (SNB) may provide accurate staging with less morbidity than axillary clearance. The aim of this study was to assess the effect of the number of sentinel nodes removed on the false-negative rate. METHODS: Data were collected prospectively from 395 women undergoing SNB for breast cancer, between June 1995 and December 2001. All nodes that were hot and/or blue were removed and analysed. RESULTS: During this interval 136 patients who had SNB were lymph node positive. The median number of sentinel nodes removed was two (range one to five). The overall false-negative rate of SNB in these women was 7.1 per cent. If only one sentinel node had been removed, the false-negative rate would have been 16.5 per cent. The removal of more than two nodes had no effect on axillary staging in all but two women. CONCLUSION: In early breast cancer, when there were multiple sentinel nodes, removal of two sentinel nodes significantly reduced the false-negative rate compared with removal of one node. Removing more than two sentinel nodes did not significantly reduce the false-negative rate further.

Adult↗
PubMed2001

Optimal N-caps for N-terminal helical templates: effects of changes in H-bonding efficiency and charge.

A family of efficient helix-initiating N-terminal caps X-Hel is introduced that expand the scope and versatility of the previously reported reporting conformational template Ac-Hel, (Kemp, D. S.; Allen, T. J.; Oslick, S. J. Am. Chem. Soc. 1995, 117, 6641-6657) and a working principle for predicting cap performance is described, based on structurally specific intramolecular hydrogen bond formation. Replacement of the N-acetyl by urethane, urea, or sulfonamide generated less efficient polypeptide helix inducers. The N-formyl cap is found to be equivalent to the N-acetyl and may provide more convenient quantitative helix reporting properties. Anionic N-caps derived from the series X = (-)O(2)C-(CH(2))(n)-CO, 0 < or = n < or = 3, are superior to N-acetyl, as are N-acylglycyl and N-acyl-beta-aspartyl. The latter pair of caps permit introduction of the X-Hel functionality within a polypeptide chain, allowing control of helicity of a peptide sub-sequence. Applications of these capping functions are discussed. This work has been focused primarily on immediate practical goals directed toward enhancing the maximum helicity of isolated short to medium-sized peptides in aqueous solution, but its developing concepts and working hypotheses are likely to significantly enhance our understanding at a chemical level of the protein folding problem.

Amides↗
PubMed2001

Short, solubilized polyalanines are conformational chameleons: exceptionally helical if N- and C-capped with helix stabilizers, weakly to moderately helical if capped with rigid spacers.

Isolating spacers introduced between solubilizing lysine regions and a polyalanine core permit rigorous characterization of context-free alanine helices. The preferred building blocks for isolating spacers are amino acids with rigid, extended conformations such as proline, isonipecotic acid, and tert-leucine. Replacing isolating spacers by conventional N- and C-caps dramatically increases the helicity of dodecaalanine. Solubilized, isolated polyalanines provide optimal tools for testing polypeptide helicity algorithms, central to resolution of the protein folding problem.

Alanine↗
PubMed2000

Interleukin 10-deficient colitis: new similarities to human inflammatory bowel disease.

BACKGROUND: Interleukin (IL) 10 is a potent anti-inflammatory cytokine. Disruption of the IL-10 gene in C57/Black6 mice results in enterocolitis in the presence of intestinal bacteria. This study investigated gut mucosal barrier function sequentially during the development of colitis in this model. METHODS: Animals were bred in specific pathogen-free conditions and transferred to conventional housing at 4 weeks. Mice were evaluated at 6, 8, 10, 12, 14 and 15 weeks of age. Barrier function was assessed by measuring intestinal permeability and antibody response to systemic endotoxaemia (antibody to the core glycolipid region of lipopolysaccharide; EndoCAb). Colons were harvested and a histological injury score (HIS) was calculated. RESULTS: The HIS increased progressively until 12 weeks, with an associated increase in intestinal permeability, and immunoglobulin (Ig) M and IgG EndoCAb. The HIS correlated positively with both intestinal permeability and IgM and IgG EndoCAb. Intestinal permeability showed a positive correlation with EndoCAb. CONCLUSION: IL-10 knockout mice develop colitis with an associated disturbance in gut mucosal barrier function, as measured by increased permeability and endotoxaemia. The colitis found in the IL-10 knockout mouse shares these histological, physiological and biochemical features with human inflammatory bowel disease and is therefore suitable for therapeutic trials. A measure of endotoxaemia correlated directly with intestinal permeability in this model.

Animals↗
PubMed2000

Probiotic therapy fails to improve gut permeability in a hapten model of colitis.

BACKGROUND: Studies in clinical and experimental inflammatory bowel disease (IBD) have shown disturbances in intestinal bacterial flora with an increase in potentially pathogenic and a decrease in protective organisms. It was hypothesized that Lactobacillus plantarum species 299 (LP299), a probiotic, would ameliorate colitis and improve intestinal permeability in experimental colitis. This study investigated the effect of LP299 in the trinitrobenzenesulfonic acid/ethanol (TNBS/E) rat model of colitis. METHODS: Twelve week old male Wistar rats were randomized to receive rectal instillates of either TNBS/E (n = 48) or saline (n = 16). For the next 7 days the animals were gavaged with 2.5 ml of oat fibre suspension containing 10(9) colony forming units (CFU) of LP299 (LP299/OF), oat fibre suspension alone (OF) or no treatment. At the end of the experiment rats received radiolabelled polyethylene glycol and urine was collected for 24 h to assess permeability. Animals were then anaesthetized and colons were harvested for colon macroscopic scoring (CMS). RESULTS: TNBS/E per rectum resulted in a greater CMS (P < 0.001) and gut permeability (P = 0.006) than saline. Administration of LP299/OF or oat fibre alone did not result in a reduction in CMS or gut permeability when compared to colitic controls. CONCLUSIONS: LP299/OF, when administered after TNBS instillation, does not reduce the severity of colitis or improve gut permeability in this hapten model of colitis.

Animals↗
PubMed1999

Increased apoptotic peripheral blood neutrophils in systemic lupus erythematosus: relations with disease activity, antibodies to double stranded DNA, and neutropenia.

OBJECTIVE: To quantify the percentage of apoptotic peripheral blood neutrophils in systemic lupus erythematosus (SLE) and to determine the relations with disease activity and neutropenia. METHODS: Neutrophil apoptosis in SLE patients (n =50) was assessed by flow cytometry using annexin V binding and fluorescent labelled anti-fas. Rheumatoid arthritis (RA, n =20) and inflammatory bowel disease patients (IBD, n =20) were studied as disease controls. RESULTS: The percentage of apoptotic neutrophils, determined by annexin V binding, was increased in peripheral blood of SLE patients (median = 3.25%) compared with normal healthy donors (n =20, median = 1.20%) and disease controls (RA: median = 1.15%) (IBD: median = 1.15%). SLE neutrophil apoptosis correlated positively with lupus disease activity measured by SLAM score. SLE patients with increased antibodies to dsDNA (>10 mg/ml) had increased apoptotic neutrophils. Eight of 14 neutropenic SLE patients had increased apoptotic neutrophils. Increased neutrophil fas expression compared with normal controls was observed in SLE, RA, and IBD. CONCLUSION: Neutrophil fas expression is increased non-specifically in inflammatory disease. Increased circulating apoptotic neutrophils in SLE correlate positively with disease activity (SLAM) and may contribute to autoantigen excess including dsDNA.

Antibodies, Antinuclear↗
PubMed1999

Lymphocyte apoptosis in systemic lupus erythematosus: relationships with Fas expression, serum soluble Fas and disease activity.

Lupus specific autoantigens are exposed on apoptotic cells. The increased number of apoptotic lymphocytes reported in systemic lupus erythematosus (SLE) may be attributable to abnormalities of lymphocyte Fas expression or serum soluble Fas. In the present study we analysed the count of circulating apoptotic lymphocytes in SLE patients (n=50), by flow cytometry using Annexin V, compared to rheumatoid arthritis patients (RA, n=20), inflammatory bowel disease patients (IBD, n=20) and normal controls (n=20). Lymphocyte Fas expression and serum soluble Fas were measured and related to numbers of apoptotic lymphocytes. The percentage of apoptotic lymphocytes, determined by Annexin V binding, was significantly increased in peripheral blood of SLE patients (median=4.2%) compared with normal healthy donors (median=1.1%) and IBD patients (median=2. 0%) but not RA (median=3.9%). SLE lymphocyte Fas expression was not significantly different from RA or IBD patients. Serum soluble Fas in SLE patients correlated positively with apoptotic lymphocytes and antibodies to double stranded DNA. This study suggests that increased apoptotic lymphocytes and increased lymphocyte Fas expression may not be specific to SLE. Serum soluble Fas may have a role in the regulation of lymphocyte apoptosis in SLE.

Adrenal Cortex Hormones↗
PubMed1997

The immune microenvironment of human fracture/soft-tissue hematomas and its relationship to systemic immunity.

The immune environment of human soft-tissue injury is unstudied. We studied fracture soft-tissue hematomas (FxSTH) in 56 patients with high-energy bony fractures. FxSTH serum and mononuclear cells (MNC) as well as fracture patient plasma and blood MNC were studied. Twenty healthy controls donated plasma and MNC. Soluble tumor necrosis factor (TNF)-alpha, interleukin (IL-1 beta, IL-2, 6, 8, 10, 12, and interferon-gamma were studied by enzyme linked immunosorbent assay. Cells were studied by flow cytometry after cell-membrane stains for CD-14, TNF-alpha (mTNF), and human leukocyte antigen-DR, or intracellular stains for TNF (icTNF) and IL-10. Thirty-six patients with Injury Severity Score < 15 were analyzed further to evaluate the effects of isolated fracture on systemic immunity. Cytokines were rarely detectable in control plasma. TNF-alpha, IL-1 beta, IL-2, and interferon-gamma were rarely found in FxSTH serum or fracture patient plasma. All FxSTH sera were rich in IL-6, peaking before 48 hours (12,538 +/- 4,153 vs. 3,494 +/- 909 pg/mL, p = 0.02, U test). In Injury Severity Score < 15, IL-6 was not detectable in most early fracture patient plasma, but rose after 48 hours (p = 0.028). FxSTH serum IL-8 peaked after 48 hours (440 +/- 289 vs. 4,542 +/- 1,219 pg/mL, p = 0.006) and circulating IL-8 appeared after 72 hours. IL-6 and IL-8 showed gradients from FxSTH serum to paired PtS (p < 0.05, Wilcoxon). IL-10 was abundant (884 +/- 229 pg/mL) in FxSTH serum < 24 hours old. FxSTH serum IL-12 peaked late (3,323 +/- 799 pg/mL, day 4-7) then fell (p < 0.001, analysis of variance). Only IL-12 was higher in fracture patient plasma (1,279 +/- 602 pg/mL) than FxSTH serum (591 +/- 327 pg/mL) during the first 48 hours (p = 0.032, U test). On flow cytometry, control monocytes expressed 201 +/- 31 mTNF sites/cell, but icTNF was absent. mTNF was up-regulated after injury more in FxSTH monocytes (3,202 +/- 870 sites/cell) than peripheral blood monocytes (584 +/- 186 sites/cell) (p < 0.05 vs. peripheral blood monocytes by Wilcoxon, p < 0.001 vs. control monocytes by U test). Intracellular IL-10 was abundant in all MNC, but varied widely after injury. Fracture and peripheral blood monocytes expressed far less human leukocyte antigen-DR than control monocytes. Fractures create an inflammatory local environment. Proximal mediators are cell-associated and relatively confined to the wound, but soluble IL-6, IL-8, and IL-10 are abundant and probably exported. Systemic MNC have complex responses to local injuries. These may reflect the combined impact of multiple soluble cytokines initially generated within the wound. FxSTH appear to be a potentially important source of immunomodulatory cytokines in trauma.

Adolescent↗