Seromuscular myotomy to help eversion of an urostomy.
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Humans↗
Biomedical subjects
D A Jones
Publications and source records attributed to D A Jones.
Characterization of the tomato Cf-4 gene for resistance to Cladosporium fulvum identifies sequences that determine recognitional specificity in Cf-4 and Cf-9.
In many interactions between plants and their pathogens, resistance to infection is specified by plant resistance (R) genes and corresponding pathogen avirulence (Avr) genes. In tomato, the Cf-4 and Cf-9 resistance genes map to the same location but confer resistance to Cladosporium fulvum through recognition of different avirulence determinants (AVR4 and AVR9) by a molecular mechanism that has yet to be determined. Here, we describe the cloning and characterization of Cf-4, which also encodes a membrane-anchored extracellular glycoprotein. Cf-4 contains 25 leucine-rich repeats, which is two fewer than Cf-9. The proteins have > 91% identical amino acids. DNA sequence comparison suggests that Cf-4 and Cf-9 are derived from a common progenitor sequence. Amino acid differences distinguishing Cf-4 and Cf-9 are confined to their N termini, delimiting a region that determines the recognitional specificity of ligand binding. The majority of these differences are in residues interstitial to those of the leucine-rich repeat consensus motif. Many of these residues are predicted to form a solvent-exposed surface that can interact with the cognate ligand. Both Cf-4 and Cf-9 are located within a 36-kb region comprising five tandemly duplicated homologous genes. These results provide further insight into the molecular basis of pathogen perception by plants and the organization of complex R gene loci.
Amino Acid Sequence↗
A comparison of intercuff and single cuff techniques of intravenous regional anaesthesia using 0.5% prilocaine mixed with technetium 99m-labelled BRIDA.
Intravenous regional anaesthesia of the upper limb is a widely used technique first described by Bier in 1908. The exact site of action of injected local anaesthetic has not been determined. We have performed intravenous regional anaesthesia on volunteers using prilocaine mixed with technetium 99m-labelled 2,4,6 trimethyl-3-bromo iminodiacetic acid. Two different techniques of intravenous regional anaesthesia (the 'normal' cuff and the intercuff techniques) were combined with gamma camera tracking of the radiolabel to determine the site of local anaesthetic action. The onset of action was similar for both techniques. The local anaesthetic was mainly retained in the antecubital fossa in both techniques but in the 'normal' technique, the local anaesthetic subsequently showed some retrograde spread. This would suggest that the main site of action of local anaesthetic used for intravenous regional anaesthesia is the larger nerves in the vicinity of the antecubital fossa.
Adult↗
Anaerobic energy production in human skeletal muscle in intense contraction: a comparison of 31P magnetic resonance spectroscopy and biochemical techniques.
Five subjects underwent twenty electrically evoked maximal isometric contractions of the anterior tibialis muscle of both legs (n = 10), with limb blood flow occluded. Measurements of muscle high-energy phosphates (ATP, ADP and phosphocreatine (PCr)), lactate and pH were made using both 31P magnetic resonance spectroscopy (MRS) and the biochemical analysis of biopsy samples obtained from directly below the MRS surface coil. The resting PCr concentration determined using MRS was similar to that measured in the biopsy material. Following contraction, MRS showed a greater decrease in ATP concentration compared with biochemical analysis (P < 0.05), but the decrease in PCr was similar. Good agreement was found when comparing resting muscle pH estimated by the two methods. Post-exercise muscle pH was, however, consistently lower with MRS and consequently the accumulation of muscle lactate estimated using MRS was markedly greater than the corresponding biochemical measurement (P < 0.05). As a result, MRS revealed an approximately 30% greater anaerobic ATP turnover during contraction, although this just failed to reach statistical significance (P > 0.05). The results of the present study indicate that there is little difference in the muscle concentration of PCr estimated by the two methods, but that there are differences in the estimates of ATP, pH and lactate changes during contraction. This latter discrepancy may lead to greater estimates of ATP turnover being made as a result of MRS analysis.
Adenosine Triphosphate↗
The effects of buspirone on perceived exertion and time to fatigue in man.
Male subjects exercised at 80% maximal rate of O2 uptake (VO2,max) following oral administration of either placebo or the partial 5-HT1A agonist buspirone (45 mg), using a paired design. Ratings of perceived exertion were higher following buspirone and time to volitional fatigue (median and inter-quartile range) fell significantly by approximately a third from 26 min (24-30 min) on placebo to 16 min (11-19 min) following buspirone. Serum prolactin was significantly elevated following buspirone administration, indicating increased hypothalamic 5-HT1A receptor stimulation. There were no significant differences in blood lactate or serum glucose between the trials. This study supports the possible central modulation of exercise tolerance by serotonergic pathways, although a role for dopamine cannot be excluded.
Adult↗
A model for phosphocreatine resynthesis.
A model for phosphocreatine (PCr) resynthesis is proposed based on a simple electric circuit, where the PCr store in muscle is likened to the stored charge on the capacitor. The solution to the second-order differential equation that describes the potential around the circuit suggests the model for PCr resynthesis is given by PCr(t) = R - [d1.exp(-k1.t) +/- d2.exp(-k2.t)], where R is PCr concentration at rest, d1, d2, k1, and k2 are constants, and t is time. By using nonlinear least squares regression, this double-exponential model was shown to fit the PCr recovery data taken from two studies involving maximal exercise accurately. In study 1, when the muscle was electrically stimulated while occluded, PCr concentrations rose during the recovery phase to a level above that observed at rest. In study 2, after intensive dynamic exercise, PCr recovered monotonically to resting concentrations. The second exponential term in the double-exponential model was found to make a significant additional contribution to the quality of fit in both study 1(P < 0.05) and study 2(P < 0.01).
Humans↗
Development of a high-volume in situ mRNA hybridization assay for the quantification of gene expression utilizing scintillating microplates.
A high-volume plate-based in situ hybridization assay has been developed, utilizing Amersham Cytostar-T scintillating microplates. This assay reliably detects specific mRNA transcripts at the level of 10-20 copies per cell. Radiolabeled antisense riboprobes specific for c-fos and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) as well as nonhomologous vector-derived control probes were used to compare mRNA levels in quiesced rat A10 smooth muscle cells after stimulation with platelet-derived growth factor (PDGF). Maximal c-fos induction occurred following stimulation of A10 cells with 30 ng/ml of PDGF, corresponding to a signal from the c-fos probe of 700 cpm. The nonhomologous control background of 50 cpm and the GAPDH signals of 1700 cpm were independent of stimulation with PDGF or serum. Using PDGF, at 30 ng/ml, quiesced cells were stimulated at various times to provide an induction time course for c-fos mRNA which peaked at 30 min and returned to basal levels within 2 h. Comparison with parallel Northern blotting experiments showed this in situ assay to be at least 20-fold more sensitive and much more rapid to perform.
Animals↗
Psychological rehabilitation after myocardial infarction: multicentre randomised controlled trial.
OBJECTIVE: To evaluate rehabilitation after myocardial infarction. DESIGN: Randomised controlled trial of rehabilitation in unselected myocardial infarction patients in six centres, baseline data being collected on admission and by structured interview (of patients and spouses) shortly after discharge and outcome being assessed by structured interview at six months and clinical examination at 12 months. SETTING: Six district general hospitals. SUBJECTS: All 2328 eligible patients admitted over two years with confirmed myocardial infarction and discharged home within 28 days. INTERVENTIONS: Rehabilitation programmes comprising psychological therapy, counselling, relaxation training, and stress management training over seven weekly group outpatient sessions for patients and spouses. MAIN OUTCOME MEASURES: Anxiety, depression, quality of life, morbidity, use of medication, and mortality. RESULTS: At six months there were no significant differences between rehabilitation patients and controls in reported anxiety (prevalence 33%) or depression (19%). Rehabilitation patients reported a lower frequency of angina (median three versus four episodes a week), medication, and physical activity. At 12 months there were no differences in clinical complications, clinical sequelae, or mortality. CONCLUSIONS: Rehabilitation programmes based on psychological therapy, counselling, relaxation training, and stress management seem to offer little objective benefit to patients who have experienced myocardial infarction compared with previous reports of smaller trials.
Angina Pectoris↗
Neutrophil adhesion to 24-hour IL-1-stimulated endothelial cells under flow conditions.
In this study, we examine neutrophil adhesion under flow conditions to cultured HUVEC stimulated for 4 or 24 h with IL-1. Interactions are measured using videomicroscopy and a parallel-plate flow system which is capable of distinguishing primary adhesion and rolling from secondary (firm) adhesion. We find that after 24 h, E-selectin does not contribute to primary adhesion, in contrast to a significant contribution after 4 h. Endothelial cell P-selectin does not contribute at either time point. Blocking or removing L-selectin from the neutrophil surface decreases adhesion 50 to 70% at either time point, and neuraminidase treatment of neutrophils decreases adhesion by 85%. These results suggest that after a 24-h stimulation, primary adhesion depends on a distinct selectin-like interaction in which a HUVEC receptor binds carbohydrates on neutrophil glycoproteins, including L-selectin. We also find that secondary adhesion in this system can be inhibited 90% with Ab blockade of CD18/ICAM-1 interactions after a 24-h stimulation, and that a combination of IL-1 and IL-4 selectively down-regulates the pathway for primary adhesion at 24 h. These results demonstrate that neutrophils adhere using different receptor pathways following 4- and 24-h stimulations, and provide experimental data characterizing some properties of the receptors involved. One of the pathways that is evident at 24 h appears to be a novel selectin-like interaction.
Blood Flow Velocity↗
Leisure-time physical activity among older adults. United States, 1990.
OBJECTIVE: To investigate the prevalence and selected correlates of leisure-time physical activity in a nationally representative sample of persons aged 65 years or older. METHODS: Data from 2783 older male and 5018 older female respondents to the 1990 National Health Interview Survey were used. Regular physical activity was defined as participation in leisure-time physical activities 3 times or more per week for 30 minutes or more during the previous 2 weeks. Odds ratios (ORs) were estimated from multivariate logistic regression analysis. RESULTS: Prevalence of regular physical activity was 37% among older men and 24% among older women. Correlates of regular physical activity included the perception of excellent to good health (men: OR, 1.5; 95% confidence interval [CI], 1.1-1.9; women: OR, 1.6; 95% CI, 1.3-1.9), correct exercise knowledge (men: OR, 2.4; 95% CI, 1.9-3.1; women: OR, 2.7; 95% CI, 2.2-3.4), no activity limitations (men: OR, 1.3; 95% CI, 1.0-1.6; women: OR, 1.7; 95% CI, 1.4-2.0) and not perceiving "a lot" of stress during the previous 2 weeks (men: OR, 1.7; 95% CI, 1.2-2.4; women: OR, 1.3; 95% CI, 1.0-1.6). Among those who had been told at least twice that they had high blood pressure, physician's advice to exercise was associated with regular physical activity (men: OR, 1.6; 95% CI, 1.2-2.3; women: OR, 1.5; 95% CI, 1.2-1.9). The 2 major activities among active older adults were walking (men, 69%; women, 75%) and gardening (men, 45%; women, 35%). CONCLUSIONS: Prevalence of regular physical activity is low among older Americans. Identifying the correlates of physical activity will help to formulate strategies to increase physical activity in this age group.
Adult↗
Prostaglandin H synthase 2 is expressed abnormally in human colon cancer: evidence for a transcriptional effect.
Evidence from epidemiological studies, clinical trials, and animal experiments indicates that inhibitors of prostaglandin synthesis lower the risk of colon cancer. We tested the hypothesis that abnormal expression of prostaglandin H synthase 2 (PHS-2), which can be induced by oncogenes and tumor promoters, occurs during colon carcinogenesis by examining its level in colon tumors. Human colon cancers were found to have an increased expression of PHS-2 mRNA compared with normal colon specimens from the same patient (n = 5). In situ hybridization showed that the neoplastic colonocytes had increased expression of PHS-2 (n = 4). Additionally, five colon cancer cell lines were shown to express high levels of PHS-2 mRNA even in the absence of a known inducer of PHS-2. To study the basis for this increased gene expression, we transfected a colon cancer cell line, HCT-116, with a reporter gene containing 2.0 kb of the 5' regulatory sequence of the PHS-2 gene. Constitutive transcription of the reporter gene was observed, whereas normal control cell lines transcribed the reporter only in response to an exogenous agonist. We conclude that PHS-2 is transcribed abnormally in human colon cancers and that this may be one mechanism by which prostaglandins or related compounds that support carcinogenesis are generated.
Adenocarcinoma↗
The tomato Cf-2 disease resistance locus comprises two functional genes encoding leucine-rich repeat proteins.
In plants, resistance to pathogens is frequently determined by dominant resistance genes, whose products are proposed to recognize pathogen-encoded avirulence gene (Avr) products. The tomato resistance locus Cf-2 was isolated by positional cloning and found to contain two almost identical genes, each conferring resistance to isolates of tomato leaf mould (C. fulvum) expressing the corresponding Avr2 gene. The two Cf-2 genes encode protein products that differ from each other by only three amino acids and contain 38 leucine-rich repeat (LRR) motifs. Of the LRRs, 20 show extremely conserved alternating repeats. The C-terminus of Cf-2 carries regions of pronounced homology to the protein encoded by the unlinked Cf-9 gene. We suggest that this conserved region interacts with other proteins involved in activating plant defense mechanisms.
Amino Acid Sequence↗
Leucocyte adhesion under flow conditions: principles important in tissue engineering.
An understanding of inflammatory responses is important in a wide variety of tissue engineering applications. This review describes the current understanding of a central aspect of inflammatory responses, the adhesion of leucocytes to blood vessel walls prior to their emigration into tissues. These highly specific adhesive interactions are mediated by three main families of receptors: the selectins, integrins, and members of the immunoglobulin superfamily. Under flow conditions, the various receptors make distinct contributions to a multistep process of adhesion in which leucocytes roll, adhere firmly, and eventually transmigrate. Two examples in which these principles are important in tissue engineering research, lymphocyte adherence in transplant rejection and monocyte adherence in atherosclerosis, are discussed in the last part of the paper.
Animals↗
Metabolism of the broad-spectrum neuropeptide growth factor antagonist: [D-Arg1, D-Phe5, D-Trp7,9, Leu11]-substance P.
Broad-spectrum neuropeptide growth factor antagonists, such as [D-Arg1, D-Phe5, D-Trp7,9, Leu11]substance P (antagonist D) and [Arg6, D-Trp7,9, NmePhe8]substance P(6-11) (antagonist G), are currently being investigated as possible anti-tumour agents. These compounds are hoped to be effective against neuropeptide-driven cancers such as small-cell lung cancer. Antagonist D possesses a broader antagonistic spectrum than antagonist G and hence may be of greater therapeutic use. The in vitro metabolism of antagonist D has been characterised and the structures of two major metabolites have been elucidated by amino acid analysis and mass spectrometry. Metabolism was confined to the C-terminus where serine carboxypeptidase action produced [deamidated]-antagonist D (metabolite 1) and [des-Leu11]-antagonist D (metabolite 2) as the major metabolites. Biological characterisation of the metabolites demonstrated that these relatively minor changes in structure resulted in a loss of antagonist activity. These results provide some of the first structure-activity information on the factors that determine which neuropeptides these compounds inhibit and on the relative potency of that inhibition.
Amino Acid Sequence↗
High-and low-frequency fatigue revisited.
Changes in excitation-contraction coupling have long been recognized as possible causes of the failure in function which occurs in fatigued muscle. High-frequency fatigue is characterized by an excessive loss of force at high frequencies of stimulation and rapid recovery when the frequency is reduced. Frequencies in excess of 50 Hz are rarely seen with voluntary activation of human muscle, and for this reason there has been some doubt as to whether high-frequency fatigue is a significant feature of normal activity. Recent experiments have shown that with 30 Hz stimulation there is a more rapid loss of force if the muscle is held isometric in a shortened position and the fatigue is rapidly reversed if the muscle is re-extended, even under ischaemic conditions. These findings are consistent with the accumulation of K+ in the t-tubules and interfibre spaces of the muscle. Low-frequency fatigue is characterized by a relative loss of force at low frequencies of stimulation and a slow recovery over the course of hours or even days. There is evidence from intracellular measurements that low-frequency fatigue is due to a reduction in Ca2+ release. However, there is a possibility that in the fatiguing exercise, the end sarcomeras of the fibre overextend and damage those in the middle section of the fibre. In this situation the active sarcomas would be working at a shorter length than predicted from the overall fibre length and the force-frequency curve will be shifted to the right. Measurements of the length-tension relationship of muscles damaged by stretching are consistent with this happening.
Animals↗
Immunomagnetic separation of Erwinia carotovora subsp. atroseptica from potato peel extracts to improve detection sensitivity on a crystal violet pectate medium or by PCR.
Immunomagnetic separation (IMS) procedures for the selective separation of Erwinia carotovora subsp. atroseptica from potato peel extract were optimized for the recovery of target and removal of non-target bacteria. A streptomycin-resistant strain of Erw. carotovora subsp. atroseptica was used in combination with a crystal violet pectate (CVP) medium supplemented with 100 micrograms ml-1 of streptomycin to determine the recovery level of the target bacterium. Recovery obtained with a polyclonal antiserum against Erw. carotovora subsp. atroseptica at a concentration of 6 micrograms IgG ml-1 was greater than that obtained with two monoclonal antibodies against lipopolysaccharides of Erw. carotovora subsp. atroseptica at a concentration of 10 micrograms IgG ml-1. A linear relationship was found between particle concentration ranging from 12 to 200 micrograms ml-1 and recovery level. When the Advanced Magnetics (AM) protein A and anti-rabbit IgG particles in the AM separation system and the Dynal anti-rabbit IgG particles in the Dynal separation system were examined, the highest recovery level per microgram of particles (66%) was obtained with the Advanced Magnetics protein A particles, followed by AM anti-rabbit particles (37%). Without IMS, detection of Erw. carotovora subsp. atroseptica in tuber peel extracts on a CVP-medium without streptomycin was impossible when the ratio of Erw. carotovora subsp. carotovora to Erw. carotovora subsp. atroseptica was greater than 100 or when large numbers of other saprophytic bacteria were present, because of overcrowding. IMS, using the AM anti-rabbit IgG particles, ensured that Erw. carotovora subsp. atroseptica could be enumerated in tuber peel extract consistently, to a detection level of 100 cells ml-1. Similarly, the IMS procedure lowered the detection level of Erw. carotovora subsp. atroseptica in a twofold diluted peel extract by PCR to ca 2.0 x 10(3) cells ml-1 or 50 cells per reaction tube. In contrast, positive results in PCR without IMS were obtained only when the peel extract was diluted 100 times and when the concentration of Erw. carotovora subsp. atroseptica was at least 10(5) cell ml-1.
Animals↗
Discrimination against same-sex couples in hotel reservation policies.
Discrimination against same-sex couples in hotel reservations policies was investigated. Hotels and bed and breakfast establishments (N = 320) were sent letters from either a same-sex or opposite-sex couple, requesting weekend reservations for a room with one bed. Same-sex couples were granted significantly fewer reservations than opposite-sex couples, suggesting that there was indeed discrimination against same-sex couples.
Female↗
Temporal expression of c-fos mRNA following balloon injury in the rat common carotid artery.
OBJECTIVE: Restenosis is a common problem which limits the effectiveness of percutaneous transluminal coronary angioplasty (PTCA). The cellular mechanisms of restenosis appear to involve smooth muscle cell (SMC) migration to the neointima in response to mitogens and growth factors, resulting in proliferation and deposition of cells in the lumen of the vessel. An antibody directed against PDGF attenuates this response in the rat. Thus, signaling cascades induced by growth factors including PDGF may be important targets for therapeutic intervention. METHODS: Since a number of growth factors activate c-fos via the p21-ras signaling pathway, we examined c-fos expression in a time course experiment involving restenotic lesions in rat carotid arteries. Sections of arteries collected at 1, 3, 7, 14 and 28 days following balloon injury were hybridized using a fluorescein-labeled RNA probe to c-fos. Immunohistochemistry was performed with antibodies to proliferating cell nuclear antigen (PCNA) and alpha-smc actin to characterize cellular constituents of the neointima, and detect any correlation between fos expression and PCNA localization. RESULTS: Expression of c-fos was low at day 1. By day 3, the media and adventitia were positively stained. At days 7 and 14, most cells in the neointima were labeled. By day 28, c-fos was expressed mainly in scattered cells along the luminal surface. Control sections revealed little labeling and confirmed specific staining by the antisense strand, PCNA localization and c-fos expression were similar at days 1, 3, 7 and 28, but at day 14 c-fos was expressed throughout the lesion, with PCNA localized mainly along the luminal edge. The majority of the cells making up the neointima stained rather intensely for alpha-smc actin, identifying them as SMCs. CONCLUSIONS: Results of these experiments indicate that, while c-fos expression correlates with lesion formation, it may be associated with a cellular process distinct from proliferation in this model.
Animals↗