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D Jenkins

Publications and source records attributed to D Jenkins.

At least 37 records · Page 2Linked to original sources
PubMed2004

Two-nucleon momentum distributions measured in 3He(e,e'pp)n.

We have measured the 3He(e,e'pp)n reaction at 2.2 GeV over a wide kinematic range. The kinetic energy distribution for "fast" nucleons (p>250 MeV/c) peaks where two nucleons each have 20% or less, and the third nucleon has most of the transferred energy. These fast pp and pn pairs are back to back with little momentum along the three-momentum transfer, indicating that they are spectators. Calculations by Sargsian and by Laget also indicate that we have measured distorted two-nucleon momentum distributions by striking one nucleon and detecting the spectator correlated pair.

Journal Article↗
PubMed2004

Observation of an exotic baryon with S=+1 in photoproduction from the proton.

The reaction gamma p-->pi(+)K(-)K(+)n was studied at Jefferson Laboratory using a tagged photon beam with an energy range of 3-5.47 GeV. A narrow baryon state with strangeness S=+1 and mass M=1555+/-10 MeV/c(2) was observed in the nK(+) invariant mass spectrum. The peak's width is consistent with the CLAS resolution (FWHM=26 MeV/c(2)), and its statistical significance is (7.8+/-1.0)sigma. A baryon with positive strangeness has exotic structure and cannot be described in the framework of the naive constituent quark model. The mass of the observed state is consistent with the mass predicted by the chiral soliton model for the Theta(+) baryon. In addition, the pK(+) invariant mass distribution was analyzed in the reaction gamma p-->K(-)K(+)p with high statistics in search of doubly charged exotic baryon states. No resonance structures were found in this spectrum.

Journal Article↗
PubMed2004

Muscle metabolism during sprint exercise in man: influence of sprint training.

In order to examine the influence of sprint training on metabolism and exercise performance during sprint exercise, 16 recreationally-active, untrained, men (VO2peak= 3.8+/-0.1 l.min(-1)) were randomly assigned to either a training (n= 8) or control group (n= 8). Each subject performed a 30-sec cycle sprint and a test to measure VO2peak before and after eight weeks of sprint training. The training group completed a series of sprints three times per week which progressed from three 30-sec cycle sprints in weeks 1 and 2, to six 30-sec sprints in weeks 7 and 8. Three mins of passive recovery separated each sprint throughout the training period. Muscle samples were obtained at rest and immediately following the pre- and post-training sprints and analysed for high energy phosphagens, glycogen and lactate; the activities of both phosphofructokinase (PFK) and citrate synthase (CS) were also measured and muscle fibre types were quantified. Training resulted in a 7.1% increase in mean power output (p<0.05), an 8% increase in VO2peak (p< 0.001), a 42% increase (p< 0.01) in CS activity and a 17% increase (p< 0.05) in resting intramuscular glycogen content. In contrast, neither PFK activity nor fibre type distribution changed with training. An increase (p< 0.05) in mean power output and attenuated (p< 0.01) ATP degradation were observed during sprint exercise following training. Glycogen degradation during sprint exercise was unaffected by sprint training. These data demonstrate that sprint training may have enhanced muscle oxidative but not glycolytic capacity.

Adaptation, Physiological↗
PubMed2004

Mucosal T-cell phenotypes in persistent atopic and nonatopic rhinitis show an association with mast cells.

BACKGROUND: Allergic rhinitis is characterized by selective expansion of T cell subsets with a CD4+ phenotype. Recently, we identified a subpopulation of nonallergic rhinitis subjects with increased epithelial mast cell and eosinophil populations, suggestive of local mucosal allergy. Previously, T cell subsets have not been characterized in this subselection of nonallergic subjects and furthermore, their relationship to mast cell and basophil effector cells remain unidentified. OBJECTIVE: To determine if a subpopulation of nonallergic subjects with idiopathic rhinitis (IR) have localized allergy confined to their nasal mucosa by comparing the T cell subsets and major histocompatibility complex (MHC) II expressing cells to persistent allergic rhinitis (PAR). Furthermore, the relationship between T cell subsets and mast cells/basophils was investigated. METHODS: None of the symptomatic patients in this study were clinically allergen-challenged. Nasal turbinate mucosa was removed from patients with PAR, IR and normal controls. Morphometry was performed on immunostained sections for T cell subset populations including CD3+, CD4+, CD8+, CD25+, CD45RA+, CD45RO+, human leucocyte antigen (HLA)-DRalpha (MHC class II), mast cell tryptase and for basophils. RESULTS: Subjects with persistent allergic rhinitis differed to normal controls in showing significantly increased numbers of total (CD3+), activated (CD25+) and allergen-naïve (CD45RA+) T lymphocytes in their nasal mucosa (P < 0.025). The naïve CD45RA+ memory T cells correlated to mucosal mast cells in PAR (P = 0.03). IR patients differ to allergic subjects in showing significantly reduced numbers of epithelial HLA-DRalpha+ cells (P = 0.007), but increased numbers of CD8+ lymphocytes (P = 0.02). The CD8+ T cells correlated with mucosal mast cell numbers (P = 0.02). In both rhinitis groups, basophils were present in very low numbers obviating the need for statistical analysis. CONCLUSION: PAR is characterized by increased numbers of CD3+, CD25+ and CD45RA+ T lymphocytes compared with normal mucosa. Allergic and nonallergic rhinitis groups can be separated by significant differences in the number of epithelial antigen presenting cells (APCs) (HLA-DRalpha+) and sub-epithelial activated (CD25+) T cells. Moreover, IR patients do not significantly differ to their allergic counterparts with respect to total (CD3+) and naïve (CD45RA+) T cell numbers, or numbers of epithelial activated (CD25+) lymphocytes. IR subjects show significantly increased numbers of CD8+ lymphocytes compared with control mucosa and although our findings suggest that the initiating inflammatory events may differ, both rhinitis groups show a similarity in pathology involving mucosal mast cells with an association to infiltrating T cells.

Adolescent↗
PubMed2003

Observation of an exotic S = +1 baryon in exclusive photoproduction from the deuteron.

In an exclusive measurement of the reaction gammad-->K(+)K(-)pn, a narrow peak that can be attributed to an exotic baryon with strangeness S=+1 is seen in the K(+)n invariant mass spectrum. The peak is at 1.542+/-0.005 GeV/c(2) with a measured width of 0.021 GeV/c(2) FWHM, which is largely determined by experimental mass resolution. The statistical significance of the peak is (5.2+/-0.6)sigma. The mass and width of the observed peak are consistent with recent reports of a narrow S=+1 baryon by other experimental groups.

Journal Article↗
PubMed2003

Measurement of the proton spin structure function g1(x,Q2) for Q2 from 0.15 to 1.6 GeV2 with CLAS.

Double-polarization asymmetries for inclusive ep scattering were measured at Jefferson Lab using 2.6 and 4.3 GeV longitudinally polarized electrons incident on a longitudinally polarized NH3 target in the CLAS detector. The polarized structure function g(1)(x,Q2) was extracted throughout the nucleon resonance region and into the deep inelastic regime, for Q(2)=0.15-1.64 GeV2. The contributions to the first moment Gamma(1)(Q2)= integral g(1)(x,Q2) dx were determined up to Q(2)=1.2 GeV2. Using a parametrization for g(1) in the unmeasured low x regions, the complete first moment was estimated over this Q2 region. A rapid change in Gamma(1) is observed for Q2<1 GeV2, with a sign change near Q(2)=0.3 GeV2, indicating dominant contributions from the resonance region. At Q(2)=1.2 GeV2 our data are below the perturbative QCD evolved scaling value.

Journal Article↗
PubMed2003

Multiphonon vibrations at high angular momentum in 182 Os.

Evidence is presented for multiphonon excitations based on a high-spin (25 Planck) intrinsic state in the deformed nucleus 182 Os. Angular momentum generation by this mode competes with collective rotation. The experimental data are compared with tilted-axis cranking calculations, supporting the vibrational interpretation. However, the lower experimental energies provide evidence that more complex interactions of states are playing a role.

Journal Article↗
PubMed2003

Measurement of ep-->e' ppi+ pi- and baryon resonance analysis.

The cross section for the reaction ep-->e(')ppi(+)pi(-) was measured in the resonance region for 1.4<W<2.1 GeV and 0.5<Q2<1.5 GeV(2)/c(2) using the CLAS detector at Jefferson Laboratory. The data show resonant structures not visible in previous experiments. The comparison of our data to a phenomenological prediction using available information on N(*) and Delta states shows an evident discrepancy. A better description of the data is obtained either by a sizable change of the properties of the P13(1720) resonance or by introducing a new baryon state, not reported in published analyses.

Journal Article↗
PubMed2003

Randomized, double-blind, placebo-controlled trial of prednisolone in post-infectious irritable bowel syndrome.

BACKGROUND: Post-infectious irritable bowel syndrome is associated with increased serotonin-containing enterochromaffin cells and lymphocytes in rectal biopsies. Animal studies have suggested that steroids reduce the lymphocyte response and suppress some of the post-infectious changes in neuromuscular function. AIM: To evaluate whether steroids reduce the number of enterochromaffin cells and improve the symptoms of post-infectious irritable bowel syndrome. METHODS: Twenty-nine patients with post-infectious irritable bowel syndrome underwent a randomized, double-blind, placebo-controlled trial of 3 weeks of oral prednisolone, 30 mg/day. Mucosal enterochromaffin cells, T lymphocytes and mast cells were assessed in rectal biopsies before and after treatment, and bowel symptoms were recorded in a daily diary. RESULTS: Initial enterochromaffin cell counts were increased and correlated with initial lamina propria T-lymphocyte counts (r = 0.460, P = 0.014). Enterochromaffin cell counts did not change significantly after either prednisolone (- 0.8% +/- 9.2%) or placebo (7.9% +/- 7.9%) (P = 0.5). Although lamina propria T-lymphocyte counts decreased significantly after prednisolone (22.0% +/- 5.6%, P = 0.003), but not after placebo (11.5% +/- 8.6%, P = 0.1), this was not associated with any significant treatment-related improvement in abdominal pain, diarrhoea, frequency or urgency. CONCLUSIONS: Prednisolone does not appear to reduce the number of enterochromaffin cells or cause an improvement in symptoms in post-infectious irritable bowel syndrome. Other approaches to this persistent condition are indicated.

Adolescent↗
PubMed2003

'Entopy': localized mucosal allergic disease in the absence of systemic responses for atopy.

BACKGROUND: The Th2 immune response in the nasal mucosa of subjects with allergic rhinitis is mediated by allergen-specific IgE. Moreover, these subjects show positive responses for markers of systemic atopy, including allergen-specific skin sensitivity and raised serum IgE titres. In contrast, idiopathic rhinitis (IR) subjects with similar histological nasal mucosal features differ in being defined as non-allergic because they have negative atopic responses. OBJECTIVE: We hypothesized that it is possible to have an allergic Th2 disease pathway localized in the nasal mucosa of 'non-allergic' rhinitis subjects despite an absence of atopic responses. METHODS: The presence of house dust mite and grass pollen-specific IgE antibodies was investigated in non-atopic (n=10) and atopic (n=11) subjects with persistent rhinitis and compared to normal (n=12) control subjects. Biotin-labelled allergen was used to localize specific allergen-binding antibodies in situ in sections of nasal mucosa. RESULTS: Grass pollen allergen binding was detected in the nasal mucosa of 3/10 non-atopic IR subjects but, in contrast, dust mite-specific antibodies were not detected. Specific antibodies were present in a total of 8/11 mucosal samples from the allergic group, but none was detected in normal control tissues. CONCLUSION: These findings support the concept of localized nasal allergy in 'non-atopic' rhinitis subjects. We propose the term 'entopy' to define this phenomenon and believe that this concept has a wider implication for localized allergic responses in other mucosal sites.

Adolescent↗
PubMed2003

Maternal ante-natal parameters as predictors of persistent postnatal glucose intolerance: a comparative study between Afro-Caribbeans, Asians and Caucasians.

AIMS: To measure the prevalence of persistent glucose intolerance at 6-12 weeks postpartum in various ethnic groups to assess the value of targeted postpartum screening. METHODS: A retrospective study was performed using computerized databases from two large maternity units within one UK region. Both units used the same screening strategy for gestational diabetes mellitus (GDM) and the same postpartum follow-up at 6-12 weeks using a 75-g oral glucose tolerance test (OGTT). A total of 221 women with a diagnosis of GDM/impaired glucose tolerance (IGT) in the index pregnancy in addition to a completed postpartum 75-g OGTT were studied. Of these, 91 were Caucasian, 89 were of Indo-Asian (Asian) origin and 41 were of Afro-Caribbean origin. RESULTS: The study showed that 35% Indo-Asians had persistent postpartum glucose intolerance compared with 7% Caucasians and 5% Afro-Caribbeans (P < 0.003). Insulin requirement during pregnancy and a diagnosis of gestational diabetes prior to 20 weeks of pregnancy were predictive for persistent postpartum glucose intolerance amongst Indo-Asians. CONCLUSIONS: The frequency of postpartum glucose intolerance among Indo-Asian women is significantly greater than among age-matched Caucasian and Afro-Caribbean women. We suggest that all Indo-Asian women with gestational diabetes should undergo postpartum screening for persistent glucose intolerance. However, in non-Asian women selective screening may be more cost effective.

Adult↗
PubMed2003

p16 immunoreactivity may assist in the distinction between endometrial and endocervical adenocarcinoma.

The distinction between an endometrial and an endocervical origin of an adenocarcinoma may be difficult, especially with small biopsy specimens or when tumor is present in both endometrial and cervical specimens. Previous studies have investigated the value of antibodies such as carcinoembryonic antigen, estrogen receptor, and vimentin in making this distinction. We investigated the value of p16 immunohistochemistry for distinguishing between an endometrial and an endocervical origin of an adenocarcinoma. Cases included in the study were endometrial adenocarcinomas of endometrioid type (n=29) and cervical adenocarcinomas of endocervical type (n=23). Cases were scored on a scale from 0 to 5 depending on the percentage of positive tumor cells: 0 (negative or occasional cells positive); 1 (<5% cells positive); 2 (5-20% cells positive); 3 (21-50% cells positive); 4 (51-99% cells positive); 5 (100% cells positive). Twenty-two of 23 (96%) endocervical adenocarcinomas were scored 5; the other was scored 0. The numbers of endometrial adenocarcinomas with scores of 0 to 5, respectively, were 1, 7, 4, 9, 5, and 3. Most primary endocervical adenocarcinomas were characterized by strong, diffuse positivity of 100% of cells with p16. Endometrial adenocarcinomas are usually positive, but positivity is generally focal and commonly involves <50% of cells. However, occasional endometrial adenocarcinomas exhibit 100% positivity. Diffuse, strong positivity with p16 suggests an endocervical rather than an endometrial origin of an adenocarcinoma. When there is morphological doubt this antibody may be of value as part of a panel for ascertaining the origin of an adenocarcinoma. Diffuse, strong positivity with p16 in endocervical adenocarcinomas is likely caused by inactivation of the retinoblastoma protein by the E7 human papillomavirus oncoprotein, which acts as a p16 transcript repressor.

Adenocarcinoma↗
PubMed2002

Eta photoproduction on the proton for photon energies from 0.75 to 1.95 GeV.

Differential cross sections for gammap-->etap have been measured with tagged real photons for incident photon energies from 0.75 to 1.95 GeV. Mesons were identified by missing mass reconstruction using kinematical information for protons scattered in the production process. The data provide the first extensive angular distribution measurements for the process above W=1.75 GeV. Comparison with preliminary results from a constituent quark model support the suggestion that a third S11 resonance with mass approximately 1.8 GeV couples to the etaN channel.

Journal Article↗
PubMed2002

Q2 Dependence of quadrupole strength in the gamma*p --> Delta(+)(1232) --> p pi(0) transition.

Models of baryon structure predict a small quadrupole deformation of the nucleon due to residual tensor forces between quarks or distortions from the pion cloud. Sensitivity to quark versus pion degrees of freedom occurs through the Q2 dependence of the magnetic (M1+), electric (E1+), and scalar (S1+) multipoles in the gamma*p-->Delta(+)-->p pi(0) transition. We report new experimental values for the ratios E(1+)/M(1+) and S(1+)/M(1+) over the range Q2 = 0.4-1.8 GeV2, extracted from precision p(e,e(')p)pi(0) data using a truncated multipole expansion. Results are best described by recent unitary models in which the pion cloud plays a dominant role.

Journal Article↗
PubMed2002

First measurement of the double spin asymmetry in (-->)e(-->)p-->e(prime)pi(+)n in the resonance region.

The double spin asymmetry in the (-->)e(-->)p --> e(prime)pi(+)n reaction has been measured for the first time in the resonance region for four-momentum transfer Q2 = 0.35-1.5 GeV(2). Data were taken at Jefferson Lab with the CLAS detector using a 2.6 GeV polarized electron beam incident on a polarized solid NH3 target. Comparison with predictions of phenomenological models shows strong sensitivity to resonance contributions. Helicity-1/2 transitions are found to be dominant in the second and third resonance regions. The measured asymmetry is consistent with a faster rise with Q(2) of the helicity asymmetry A1 for the F(15)(1680) resonance than expected from the analysis of the unpolarized data.

Journal Article↗
PubMed2002

Successful treatment of post-transplant lymphoproliferative disorder in autologous blood stem cell transplant recipients.

We report three cases of post-transplant lymphoproliferative disorder (PTLD) in the context of autologous stem cell transplantation (ASCT) for multiple myeloma (MM) and non-Hodgkin's lymphoma. The first two cases received ASCT for MM, one with a CD34-selected autograft and the other with an unmanipulated autograft. Both these cases of PTLD achieved a complete response following treatment with IVIG, gancyclovir, solumedrol and interferon (IFN). The third case received ASCT with an unmanipulated autograft for relapsed angioimmunoblastic lymphoma. He also achieved a complete response but only after rituximab was added to IVIG, gancyclovir, solumedrol and IFN. None of these patients experienced a relapse of their PTLD with follow-up ranging from 1.5 to 5 years. These cases highlight the importance of considering PTLD in the differential diagnosis of lymphadenopathy and fever post ASCT. They also demonstrate the possibility of durable complete remission of post-ASCT PTLD following antiviral and immune modulating therapy.

Adult↗
PubMed2002

Immunohistochemical staining with MIB1, bcl2 and p16 assists in the distinction of cervical glandular intraepithelial neoplasia from tubo-endometrial metaplasia, endometriosis and microglandular hyperplasia.

AIMS: Preinvasive endocervical glandular lesions, termed cervical glandular intraepithelial neoplasia, are increasing in incidence. The distinction of cervical glandular intraepithelial neoplasia from benign mimics, especially tubo-endometrial metaplasia, endometriosis and microglandular hyperplasia, can be difficult. This study investigates the value of immunohistochemical staining with MIB1, bcl2 and p16 in the distinction of cervical glandular intraepithelial neoplasia from these benign mimics. METHODS AND RESULTS: Immunohistochemical staining using the monoclonal antibodies MIB1, bcl2 and p16 was performed on cases of cervical glandular intraepithelial neoplasia (n = 21), tubo-endometrial metaplasia (n = 13), endometriosis (n = 7) and microglandular hyperplasia (n = 14). With tubo-endometrial metaplasia and microglandular hyperplasia staining with MIB1 was either negative or involved <10% of cells, while with cervical glandular intraepithelial neoplasia the majority of cases (86%) exhibited >10% positive cells. Two cases of endometriosis exhibited a MIB1 index of 10-30% while in the other cases <10% cells stained. With bcl2 the cells of microglandular hyperplasia were negative although there was staining of associated reserve cells in 43% of cases. All cases of tubo-endometrial metaplasia except one and all cases of endometriosis stained diffusely positive with bcl2. Cases of cervical glandular intraepithelial neoplasia were negative or exhibited focal staining. With p16 all cases of cervical glandular intraepithelial neoplasia exhibited diffuse strong positivity, generally involving 100% of cells, while all cases of microglandular hyperplasia were negative. Sixty-two percent of cases of tubo-endometrial metaplasia showed focal positivity, the remainder being negative. Cases of tubo-endometrial metaplasia were never diffusely positive with p16. In three cases of endometriosis there was staining of >50% of cells while the other cases were either focally positive or negative. CONCLUSIONS: A panel of antibodies, comprising MIB1, bcl2 and p16, is a useful adjunct to histology in distinguishing cervical glandular intraepithelial neoplasia from tubo-endometrial metaplasia, endometriosis and microglandular hyperplasia. Cases of cervical glandular intraepithelial neoplasia are diffusely positive for p16 and generally exhibit a high proliferation index with MIB1, while bcl2 is negative or, at most, focally positive. Tubo-endometrial metaplasia and endometriosis are characterized by strong diffuse positivity with bcl2 and a low proliferation index with MIB1 (although occasional cases of endometriosis show moderate proliferative activity). p16 is negative or exhibits focal positivity in tubo-endometrial metaplasia but in endometriosis there may be quite widespread positivity. Microglandular hyperplasia shows a low proliferation index with MIB1 and is negative for bcl2 and p16.

Antibodies, Monoclonal↗