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M Jones

Publications and source records attributed to M Jones.

At least 235 records · Page 13Linked to original sources
PubMed1999

The role of the NH(2)- and COOH-terminal domains of the inhibitory region of troponin I in the regulation of skeletal muscle contraction.

The role of the inhibitory region of troponin (Tn) I in the regulation of skeletal muscle contraction was studied with three deletion mutants of its inhibitory region: 1) complete (TnI-(Delta96-116)), 2) the COOH-terminal domain (TnI-(Delta105-115)), and 3) the NH(2)-terminal domain (TnI-(Delta95-106)). Measurements of Ca(2+)-regulated force and relaxation were performed in skinned skeletal muscle fibers whose endogenous TnI (along with TnT and TnC) was displaced with high concentrations of added troponin T. Reconstitution of the Tn-displaced fibers with a TnI.TnC complex restored the Ca(2+) sensitivity of force; however, the levels of relaxation and force development varied. Relaxation of the fibers (pCa 8) was drastically impaired with two of the inhibitory region deletion mutants, TnI-(Delta96-116).TnC and TnI-(Delta105-115).TnC. The TnI-(Delta95-106).TnC mutant retained approximately 55% relaxation when reconstituted in the Tn-displaced fibers. Activation in skinned skeletal muscle fibers was enhanced with all TnI mutants compared with wild-type TnI. Interestingly, all three mutants of TnI increased the Ca(2+) sensitivity of contraction. None of the TnI deletion mutants, when reconstituted into Tn, could inhibit actin-tropomyosin-activated myosin ATPase in the absence of Ca(2+), and two of them (TnI-(Delta96-116) and TnI-(Delta105-115)) gave significant activation in the absence of Ca(2+). These results suggest that the COOH terminus of the inhibitory region of TnI (residues 105-115) is much more critical for the biological activity of TnI than the NH(2)-terminal region, consisting of residues 95-106. Presumably, the COOH-terminal domain of the inhibitory region of TnI is a part of the Ca(2+)-sensitive molecular switch during muscle contraction.

Amino Acid Sequence↗
PubMed1999

New echocardiographic windows for quantitative determination of aortic regurgitation volume using color Doppler flow convergence and vena contracta.

Color Doppler images of aortic regurgitation (AR) flow acceleration, flow convergence (FC), and the vena contracta (VC) have been reported to be useful for evaluating severity of AR. However, clinical application of these methods has been limited because of the difficulty in clearly imaging the FC and VC. This study aimed to explore new windows for imaging the FC and VC to evaluate AR volumes in patients and to validate this in animals with chronic AR. Forty patients with AR and 17 hemodynamic states in 4 sheep with strictly quantified AR volumes were evaluated. A Toshiba SSH 380A with a 3.75-MHz transducer was used to image the FC and VC. After routine echo Doppler imaging, patients were repositioned in the right lateral decubitus position, and the FC and VC were imaged from high right parasternal windows. In only 15 of the 40 patients was it possible to image clearly and measure accurately the FC and VC from conventional (left decubitus) apical or parasternal views. In contrast, 31 of 40 patients had clearly imaged FC regions and VCs using the new windows. In patients, AR volumes derived from the FC and VC methods combined with continuous velocity agreed well with each other (r = 0.97, mean difference = -7.9 ml +/- 9.9 ml/beat). In chronic animal model studies, AR volumes derived from both the VC and the FC agreed well with the electromagnetically derived AR volumes (r = 0.92, mean difference = -1.3 +/- 4.0 ml/beat). By imaging from high right parasternal windows in the right decubitus position, complementary use of the FC and VC methods can provide clinically valuable information about AR volumes.

Adolescent↗
PubMed1999

Three-dimensional reconstruction of the color Doppler-imaged vena contracta for quantifying aortic regurgitation: studies in a chronic animal model.

BACKGROUND: The purpose of this study was to investigate the use of 3-dimensional (3D) reconstruction of color Doppler flow maps to image and extract the vena contracta cross-sectional area to determine the severity of aortic regurgitation (AR) in an animal model. Evaluation of the vena contracta with 2-dimensional imaging systems may not be sufficiently robust to fully characterize this region, which may be asymmetrically shaped. METHODS AND RESULTS: In 6 sheep with surgically induced chronic AR, 18 hemodynamically different states were studied. Instantaneous regurgitant flow rates were obtained by aortic and pulmonary electromagnetic flowmeters (EMFs) as reference standards, and aortic regurgitant effective orifice areas (EOAs) were determined from EMF regurgitant flow rates divided by continuous-wave (CW) Doppler velocities. Composite video data for color Doppler imaging of the aortic regurgitant flows were transferred into a TomTec computer after computer-controlled 180 degrees rotational acquisition. After the 3D data transverse to the flow jet were sectioned, the smallest proximal jet cross section was identified for direct measurement of the vena contracta area. Peak regurgitant flow rates and regurgitant stroke volumes were calculated as the product of these areas and the CW Doppler peak velocities and velocity-time integrals, respectively. There was an excellent correlation between the 3D-derived vena contracta areas and reference EOAs (r=0.99, SEE=0.01 cm2) and between 3D and reference peak regurgitant flow rates and regurgitant stroke volumes (r=0.99, difference=0.11 L/min; r=0.99, difference=1.5 mL/beat, respectively). CONCLUSIONS: 3D-based determination of the vena contracta cross-sectional area can provide accurate quantification of the severity of AR.

Animals↗
PubMed1999

Socioeconomic differences in childhood consultation rates in general practice in England and Wales: prospective cohort study.

OBJECTIVE: To establish how consultation rates in children for episodes of illness, preventive activities, and home visits vary by social class. DESIGN: Analysis of prospectively collected data from the fourth national survey of morbidity in general practice, carried out between September 1991 and August 1992. SETTING: 60 general practices in England and Wales. SUBJECTS: 106 102 children aged 0 to 15 years registered with the participating practices. MAIN OUTCOME MEASURES: Mean overall consultation rates for any reason, illness by severity of underlying disease, preventive episodes, home visits, and specific diagnostic category (infections, asthma, and injuries). RESULTS: Overall consultation rates increased from registrar general's social classes I-II to classes IV-V in a linear pattern (for IV-V v I-II rate ratio 1.18; 95% confidence interval 1.14 to 1. 22). Children from social classes IV-V consulted more frequently than children from classes I-II for illnesses (rate ratio 1.23; 1.15 to 1.30), including infections, asthma, and injuries and poisonings. They also had significantly higher consultation rates for minor, moderate, and serious illnesses and higher home visiting rates (rate ratio 2.00; 1.81 to 2.18). Consultations for preventive activities were lower in children from social classes IV-V than in children from social classes I-II (rate ratio 0.95; 0.86 to 1.05). CONCLUSIONS: Childhood consultation rates for episodes of illness increase from social classes I-II through to classes IV-V. The findings on severity of underlying illness suggest the health of children from lower social classes is worse than that of children from higher social classes. These results reinforce the need to identify and target children for preventive health care in their socioeconomic context.

Adolescent↗
PubMed1999

Heparin is essential for a single keratinocyte growth factor molecule to bind and form a complex with two molecules of the extracellular domain of its receptor.

Keratinocyte growth factor (KGF or FGF-7) is a member of the heparin binding fibroblast growth factor (FGF) family and is a paracrine mediator of proliferation and differentiation of a wide variety of epithelial cells. To examine the stoichiometry of complexes formed between KGF and its receptor, we have utilized a soluble variant of the extracellular region of the KGF receptor containing two tandem immunoglobulin-like loops, loops II and III (sKGFR). Ligand-receptor complexes were examined by size exclusion chromatography, light scattering, N-terminal protein sequencing, and sedimentation velocity. In the presence of low-molecular mass heparin ( approximately 3 kDa), we demonstrate the formation of complexes containing two molecules of sKGFR and one molecule of KGF. In the absence of heparin, we were unable to detect any KGF-sKGFR complexes using the above techniques, and additional studies in which sedimentation equilibrium was used show that the binding is very weak (Kd >/= 70 microM). Furthermore, using heparin fragments of defined size, we demonstrate that a heparin octamer or decamer can promote formation of a 2:1 complex, while a hexamer does not. Utilizing the highly purified proteins and defined conditions described in this study, we find that heparin is obligatory for formation of a KGF-sKGFR complex. Finally, 32D cells, which appear to lack low-affinity FGF binding sites, were transfected with a KGFR-erythropoeitin receptor chimera and were found to require heparin to achieve maximal KGF stimulation. Our data are consistent with the previously described concept that cell- or matrix-associated heparan sulfate proteoglycans (HSPGs) and FGF ligands participate in a concerted mechanism that facilitates FGFR dimerization and signal transduction in vivo.

Amino Acid Sequence↗
PubMed1999

LYVE-1, a new homologue of the CD44 glycoprotein, is a lymph-specific receptor for hyaluronan.

The extracellular matrix glycosaminoglycan hyaluronan (HA) is an abundant component of skin and mesenchymal tissues where it facilitates cell migration during wound healing, inflammation, and embryonic morphogenesis. Both during normal tissue homeostasis and particularly after tissue injury, HA is mobilized from these sites through lymphatic vessels to the lymph nodes where it is degraded before entering the circulation for rapid uptake by the liver. Currently, however, the identities of HA binding molecules which control this pathway are unknown. Here we describe the first such molecule, LYVE-1, which we have identified as a major receptor for HA on the lymph vessel wall. The deduced amino acid sequence of LYVE-1 predicts a 322-residue type I integral membrane polypeptide 41% similar to the CD44 HA receptor with a 212-residue extracellular domain containing a single Link module the prototypic HA binding domain of the Link protein superfamily. Like CD44, the LYVE-1 molecule binds both soluble and immobilized HA. However, unlike CD44, the LYVE-1 molecule colocalizes with HA on the luminal face of the lymph vessel wall and is completely absent from blood vessels. Hence, LYVE-1 is the first lymph-specific HA receptor to be characterized and is a uniquely powerful marker for lymph vessels themselves.

Amino Acid Sequence↗
PubMed1999

Human herpesvirus 6 seronegativity before transplantation predicts the occurrence of fungal infection in liver transplant recipients.

BACKGROUND: Invasive fungal infection has a major impact on the morbidity and mortality of liver transplant recipients. Human herpesvirus (HHV)-6 infection after transplantation is associated with an immunosuppressive state and the development of cytomegalovirus disease. Because cytomegalovirus infection is a risk factor for invasive fungal infection after transplantation, we have examined whether HHV-6 and fungal infection are associated after transplantation. METHODS: Pretransplantation sera from 247 consecutive liver transplant recipients were analyzed for IgG to HHV-6. Thirty-three (13%) HHV-6-seronegative recipients were identified. Six of 33 (18%) seronegative recipients experienced fungal infection as compared with 15 of 214 (7%) seropositive recipients (P=0.034). RESULTS: In a univariate analysis of risk factors for fungal infection, pretransplantation seronegativity to HHV-6 (P=0.034), intraoperative cryoprecipitate requirements greater than the 75th percentile (P=0.035), reoperation (P=0.005), biliary stricturing postoperatively (P=0.046), and gastrointestinal or vascular complications postoperatively (P=0.030) were identified as significant risk factors. Moreover, in pairwise multivariate analysis, pretransplantation HHV-6 seronegativity remained a significant variable even in the presence of each of the other variables. CONCLUSIONS: These results suggest that HHV-6 seronegativity before transplantation is a valuable clinical marker that identifies patients at risk for developing fungal infection after transplantation.

Disease-Free Survival↗
PubMed1999

Immunohistochemical screening for oncogenic tyrosine kinase activation.

Tyrosine kinases causing the abnormal phosphorylation of intracellular proteins have been shown to contribute to oncogenic transformation in a number of human neoplasms. Immunohistological staining of routine biopsy sections for increased levels of phosphotyrosine may therefore provide a simple means of screening for tumours containing activated tyrosine kinases. In this study, monoclonal antibodies to phosphotyrosine were used to immunostain a cell line and tumour biopsies from lymphomas known to contain the activated anaplastic-lymphoma-kinase (ALK) tyrosine kinase. A range of normal and other neoplastic tissues were also immunostained for comparison. An anaplastic large cell lymphoma (ALCL) cell line carrying the (2;5) translocation, which creates the activated nucleophosmin-anaplastic lymphoma kinase (NPM-ALK) tyrosine kinase, was strongly labelled. Routine tissue biopsies from five cases of ALK-positive ALCL were also strongly positive for phosphotyrosine. The characteristic granular cytoplasmic labelling pattern for phosphotyrosine observed in a B-cell lymphoma (expressing full length ALK kinase) was identical to that obtained using an ALK-specific antibody, thus confirming that labelling for phosphotyrosine in lymphoma cells reflects the presence of an activated kinase. When normal lymphoid tissues were stained, there was little or no labelling for phosphotyrosine, but stronger labelling was seen in other cells and tissues; for example, endothelial cells and some carcinoma samples. Whilst the strong labelling for phosphotyrosine observed in the lymphoma cells is due to the presence of activated ALK, the strong staining of some normal cells presumably represents physiologically active kinases and this should be taken into account when interpreting the immunostaining of non-lymphoid tumours. The simplicity of this method, however, means that it offers a new rapid approach to the screening of large numbers of tumours for the presence of aberrant tyrosine kinase activation, particularly if they arise from tissues which normally contain only background levels of phosphotyrosine.

Antibodies, Monoclonal↗
PubMed1999

Soluble CD14 acts as a negative regulator of human T cell activation and function.

T cell activation is controlled by the coordination of stimulatory and negative regulatory signals which are not completely defined. In this study we tested for a possible direct effect of CD14 on the regulation of T cell activation and function. We show that soluble CD14 (sCD14) induces inhibition of antigen-mediated peripheral blood mononuclear cells (PBMC) proliferation and anti-CD3-mediated proliferation of CD4+CD8+, CD4+CD8+ and CD4+CD8+ Tcell clones. This effect is not due to cell death, but results from a marked inhibition of IL-2 production. Proliferation of T cell clones due to exogenous IL-2 is not affected by sCD14. We also found that sCD14 inhibits production of another Th1-like cytokine, IFN-gamma and a Th2-like cytokine, IL-4. Importantly, sCD14 induces a progressive accumulation of the inhibitory protein IkappaB-alpha. We show that sCD14 binds to activated T cells. Following cell activation, biotinylated sCD14 stains CD3+ PBMC, as well as human T cell clones with varying intensity. The binding is saturable, can be inhibited by excess of unlabeled sCD14 and, following binding, sCD14 is internalized. Collectively, these findings reveal a previously unrecognized function of sCD14, namely its capacity to negatively regulate T lymphocyte activation and function by interacting directly with activated T cells.

Biological Transport, Active↗
PubMed1999

Liver and bile duct pathology following Cryptosporidium parvum infection of immunodeficient mice.

Patients with acquired immune deficiency syndrome (AIDS) and boys with mutations of the CD154 gene (causing congenital X-linked immunodeficiency with hyper-IgM [XHIM]) are susceptible to chronic infections of the biliary tract with Cryptosporidium parvum (CP) that may lead to biliary sclerosis and ultimately to cholangiocarcinoma. To determine whether the CP infection and the consequent immune response contribute independently to this morbidity, we infected mice with severe combined immunodeficiency (SCID) or with disrupted genes for CD154, CD40, or interferon gamma (IFN-gamma) with CP. Even when CP infection persisted for 16 weeks, the SCID mice developed only mild triaditis, without apoptosis of biliary epithelial cells (BEC). Fifty percent of the CD154 knockout mice developed lobular hepatitis with acute and chronic triaditis. The CD40 knockout mice developed marked triaditis, and the IFN-gamma knockouts either succumbed to enteritis or survived to develop marked triaditis, portal fibrosis, biliary sclerosis, necrosis with dilation of duct-like structures within the porta hepatis, and dysplastic changes. CP-infected SCID mice reconstituted with T cells from IFN-gamma knockout donors either developed severe enteritis or survived to develop triaditis, cholangitis, lobular hepatitis with periductular sclerosis, and scarring. Mice with disruptions of both the CD40 and IFN-gamma genes remained infected by CP and developed bile duct and liver disease, but not enteritis. Our results suggest that T-cell cytokines are required for the inflammatory and sclerosing responses to CP infection in immunodeficient animals. The response of immunodeficient mice to CP infection may model at least the initial steps toward the development of sclerosing cholangitis or bile duct cancers in XHIM patients.

Animals↗
PubMed1999

Hypothalamo-pituitary-adrenal axis responses to lipopolysaccharide in male and female rats with adjuvant-induced arthritis.

We have previously demonstrated that rats with adjuvant-induced arthritis (AA) are unable to mount a hypothalamo-pituitary-adrenal (HPA) axis response to either psychological or physical stress. In the present study we have taken male and female rats with AA and injected these with lipopolysaccharide (LPS) as an acute immune challenge and assessed the effects of this challenge at all levels of the HPA axis. We have demonstrated that, in contrast to acute stress, there is an activation of the HPA axis in male AA rats in response to acute immune challenge which occurs at all levels of the HPA axis. The hypothalamic and pituitary response to LPS is intact in the female AA rat. However, there appears to be an impaired adrenal responsiveness in the AA female given LPS. The non-AA female is able to respond to LPS suggesting that this defect is not inherent but is a reaction to the development of inflammation. This hyporesponsiveness has major implications for the ability of the organism to survive infections or immune challenges which are potentially life threatening in the absence of release of anti-inflammatory glucocorticoids from the adrenal cortex. The implications of these changes in the female on the subsequent development of the disease and the mechanisms mediating these effects may provide a better understanding of the gender differences underlying susceptibility to autoimmune diseases.

Adrenocorticotropic Hormone↗
PubMed1999

Sips, Sops, and SPIs but not stn influence Salmonella enteropathogenesis.

The virulence factors influencing Salmonella-induced enteropathogenesis remain poorly characterised. The interactions of different serotypes of Salmonella with bovine ileal mucosa have been characterised in the ligated ileal loop model. In a quantitative intestinal invasion assay Salmonella dublin, S. choleraesuis, S. gallinarum, and S. abortusovis strains were all recovered from ileal mucosa, either with or without Peyer's patches in similar numbers. This observation suggests that the magnitude and route of intestinal invasion does not mediate Salmonella serotype host specificity. Despite being equally invasive there was a clear hierarchy in the enteropathogenicity of these serotypes. The magnitude of the enteropathogenic responses did not correlate to serotype host specificity. These observations implicate undefined serotype specific factors in influencing enteropathogenicity independently of intestinal invasion. Disruption of genes in Salmonella Pathogenicity Island (SPI) 1 of S. typhimurium and S. dublin blocked the secretion of Salmonella Invasion Proteins (Sips) and Salmonella Outer Proteins (Sops). These mutants were significantly less invasive and enteropathogenic then the wild type strain in ligated ileal loops. Disruption of sopB and sopD significantly reduced enteropathogenesis, but without influencing intestinal invasion. These two genes appear to act in concert. Surprisingly, disruption of stn, the Salmonella enterotoxin gene cloned on the basis of its homology to cholera toxin, did not influence enteropathogenesis. SopB was mapped to the 20 centisome of S. typhimurium and is flanked by 5 genes that are organised in a manner typical of a pathogenicity island, which we have termed SPI-5. Mutation of the other genes in SPI-5 also attenuated enteropathogenesis but not virulence for mice, suggesting SPI-5 is a key locus specifically influencing Salmonella enteropathogenesis.

Animals↗
PubMed1999

Study of gene delivery in a rabbit vein graft model. Improvement of the efficiency of gene transfer into vein grafts.

Gene therapy is a therapeutic strategy in treating cardiovascular disease. Vein graft failure, the major limitation on coronary artery bypass surgery, may be amenable to gene approaches. Some studies describe gene therapies using functioning genes to prevent vein graft stenosis. Gene transfer efficiency remains a major issue. In this rabbit vein graft model, we studied gene delivery using a replication-deficit recombinant adenovirus to improve gene transfer efficiency into vein grafts. The adenovirus vector that contains the E.coli lacZ gene encoding beta gal was used because this vector is widely used and thought to be effective. Gene transfer was detected by X-gal staining. We hypothesized that dimethylsulfoxide and hyaluronidase, both drug delivery enhancers, would improve efficiency and that, in transfer to adventitia, direct injection would be more effective than dwelling. We studied 3 gene delivery methods to intima and media (controls, using dimethylsulfoxide and using hyaluronidase before transfection) and 2 delivery methods to adventitia (direct injection and dwelling). We used 6 rabbits per delivery method. X-gal stained positive cell rates were counted using light microscopy. Our findings indicate that (1) dimethylsulfoxide increased the efficiency of transfection to media and intima, (2) hyaluronidase increased intimal transfection efficiency, (3) direct injection to adventitia was more effective than dwelling. These findings suggest that in vein grafting, our methods are feasible for improving gene transfer efficiency.

Adenoviridae↗
PubMed1999

Evidence that Par-4 participates in the pathogenesis of HIV encephalitis.

Progressive neuronal degeneration in brain regions involved in learning and memory processes is a common occurrence in patients infected with human immunodeficiency virus type 1 (HIV-1). We now report that levels of Par-4, a protein recently linked to neuronal apoptosis in Alzheimer's disease, are increased in neurons in hippocampus of human patients with HIV encephalitis and in monkeys infected with a chimeric strain of HIV-1 and simian immunodeficiency virus. Par-4 levels increased rapidly in cultured hippocampal neurons following exposure to the neurotoxic HIV-1 protein Tat, and treatment of the cultures with a Par-4 antisense oligonucleotide protected the neurons against Tat-induced apoptosis. Additional findings show that Par-4 participates at an early stage of Tat-induced neuronal apoptosis before caspase activation, oxidative stress, and mitochondrial dysfunction. Our data suggest that Par-4 may be a mediator of neuronal apoptosis in HIV encephalitis and that therapeutic approaches targeting the Par-4 apoptotic cascade may prove beneficial in preventing neuronal degeneration and associated dementia in patients infected with HIV-1.

Animals↗
PubMed1999

Intraperitoneal nutrition.

Provision of nutrients through the peritoneum is as old as peritoneal dialysis (PD) itself. Studies with a shelf-stable amino acid-based dialysis solution have shown that the amino acids absorbed during one exchange quantitatively exceed the daily losses of proteins and amino acids. The supplementary amino acids are well tolerated and can induce protein anabolism in many malnourished PD patients, as is evident from increased nitrogen balance, insulin-like growth factor-1, and increased concentrations of serum proteins. Such solutions offer a convenient means of providing nutritional supplementation to address the major nutritional needs of PD patients.

Humans↗
PubMed1999

Validation of the accuracy of both right and left ventricular outflow volume determinations and semiautomated calculation of shunt volumes through atrial septal defects by digital color Doppler flow mapping in a chronic animal model.

OBJECTIVES: The aim of the present study was to quantitate shunt flow volumes through atrial septal defects (ASDs) in a chronic animal model with surgically created ASDs using a new semiautomated color Doppler flow calculation method (ACM). BACKGROUND: Because pulsed Doppler is cumbersome and often inappropriate for color flow computation, new methods such as ACM are of interest. METHODS: In this study, 13 to 25 weeks after ASDs were surgically created in eight sheep, a total of 24 hemodynamic states were studied at a separate open chest experimental session. Electromagnetic (EM) flow probes and meters were used to provide reference flow volumes as the pulmonary and aortic flow volumes (Qp and Qs) and shunt flow volumes (Qp minus Qs). Epicardial echocardiographic studies were performed to image the left and right ventricular outflow tract (LVOT and RVOT) forward flow signals. The ACM method digitally integrated spatial and temporal color flow velocity data to provide stroke volumes. RESULTS Left ventricular outflow tract and RVOT flow volumes obtained by the ACM method agreed well with those obtained by the EM method (r = 0.96, mean difference = 0.78 +/- 1.7 ml for LVOT and r = 0.97, mean difference = -0.35 +/- 3.6 ml for RVOT). As a result, shunt flow volumes and Qp/Qs by the ACM method agreed well with those obtained by the EM method (r = 0.96, mean difference = -1.1 +/- 3.6 ml/beat for shunt volumes and r = 0.95, mean difference = -0.11 +/- 0.22 for Qp/Qs). CONCLUSIONS: This animal study, using strictly quantified shunt flow volumes, demonstrated that the ACM method can provide Qp/Qs and shunt measurements semiautomatically and noninvasively.

Animals↗