Biomedical subjects

E Johnson

Publications and source records attributed to E Johnson.

At least 37 records · Page 2Linked to original sources

PubMed2001

Evidence of New States Decaying into Xi(*)(c)pi.

Using 13.7 fb(-1) of data recorded by the CLEO detector at Cornell Electron Storage Ring, we report evidence of two new charmed baryons: one decaying into Xi(0')(c)pi(+) with the subsequent decay Xi(0')(c)-->Xi(0)(c)gamma, and its isospin partner decaying into Xi(+')(c)pi(-) followed by Xi(+')(c)-->Xi(+)(c)gamma. We measure the following mass differences for the two states: M(Xi(0)(c)gammapi(+))-M(Xi(0)(c)) = 318.2+/-1.3+/-2.9 MeV and M(Xi(+)(c)gammapi(-))-M(Xi(+)(c)) = 324.0+/-1.3+/-3.0 MeV. We interpret these new states as the J(P) = 1 / 2(-) Xi(c1) particles, the charmed-strange analogs of the Lambda(+)(c1)(2593).

Journal Article↗

PubMed2001

Observation of B --> phiK and B --> phiK*.

We have studied two-body charmless hadronic decays of B mesons into the final states straight phiK and phiK(*). Using 9.7 million B&Bmacr; pairs collected with the CLEO II detector, we observe the decays B- --> phiK- and B0--> phiK(*0) with the following branching fractions: B(B--->phiK-) = (5.5(+2.1)(-1.8)+/-0.6)x10(-6) and B(B0--> phiK(*0)) = (11.5(+4.5+1.8)(-3.7-1.7))x10(-6). We also see evidence for the decays B0-->phiK0 and B---> phiK(*-). However, since the statistical significance is not overwhelming for these modes, we determine upper limits of <12.3x10(-6) and <22.5x10(-6) ( 90% confidence level), respectively.

Journal Article↗

PubMed2001

Crystal structures of a novel ferric reductase from the hyperthermophilic archaeon Archaeoglobus fulgidus and its complex with NADP+.

BACKGROUND: Studies performed within the last decade have indicated that microbial reduction of Fe(III) to Fe(II) is a biologically significant process. The ferric reductase (FeR) from Archaeoglobus fulgidus is the first reported archaeal ferric reductase and it catalyzes the flavin-mediated reduction of ferric iron complexes using NAD(P)H as the electron donor. Based on its catalytic activity, the A. fulgidus FeR resembles the bacterial and eukaryotic assimilatory type of ferric reductases. However, the high cellular abundance of the A. fulgidus FeR (approximately 0.75% of the total soluble protein) suggests a catabolic role for this enzyme as the terminal electron acceptor in a ferric iron-based respiratory pathway [1]. RESULTS: The crystal structure of recombinant A. fulgidus FeR containing a bound FMN has been solved at 1.5 A resolution by multiple isomorphous replacement/ anomalous diffraction (MIRAS) phasing methods, and the NADP+- bound complex of FeR was subsequently determined at 1.65 A resolution. FeR consists of a dimer of two identical subunits, although only one subunit has been observed to bind the redox cofactors. Each subunit is organized around a six-stranded antiparallel beta barrel that is homologous to the FMN binding protein from Desulfovibrio vulgaris. This fold has been shown to be related to a circularly permuted version of the flavin binding domain of the ferredoxin reductase superfamily. The A. fulgidus ferric reductase is further distinguished from the ferredoxin reductase superfamily by the absence of a Rossmann fold domain that is used to bind the NAD(P)H. Instead, FeR uses its single domain to provide both the flavin and the NAD(P)H binding sites. Potential binding sites for ferric iron complexes are identified near the cofactor binding sites. CONCLUSIONS: The work described here details the structures of the enzyme-FMN, enzyme-FMN-NADP+, and possibly the enzyme-FMN-iron intermediates that are present during the reaction mechanism. This structural information helps identify roles for specific residues during the reduction of ferric iron complexes by the A. fulgidus FeR.

Archaeoglobus fulgidus↗

PubMed2001

Search for B --> tau(nu) and B --> K(nu)nu.

We report results of a search for B-->tau(nu) in a sample of 9.7 x 10(6) charged B meson decays. We exclusively reconstruct the companion B decay to suppress background. We set an upper limit on the branching fraction B(B-->tau(nu))<8.4 x 10(-4) at 90% confidence level. We also establish B(B+/--->K+/-nu(nu))<2.4 x 10(-4) at 90% confidence level.

Journal Article↗

PubMed2001

Measurement of the relative branching fraction of upsilon(4S) to charged and neutral B-meson pairs.

We analyze 9.7x10(6) B_B pairs recorded with the CLEO detector to determine the production ratio of charged to neutral B-meson pairs produced at the Upsilon(4S) resonance. We measure the rates for B0-->J/psiK((*)0) and B+-->J/psiK((*)+) decays and use the world-average B-meson lifetime ratio to extract the relative widths f(+-) / f(00) = gamma(Upsilon(4S)-->B+B-) / gamma(Upsilon(4S)-->B0 B-0)) = 1.04+/-0.07(stat)+/-0.04(syst). With the assumption that f(+-)+f(00) = 1, we obtain f(00) = 0.49+/-0.02(stat)+/-0.01(syst) and f(+-) = 0.51+/-0.02(stat)+/-0.01(syst). This production ratio and its uncertainty apply to all exclusive B-meson branching fractions measured at the Upsilon(4S) resonance.

Journal Article↗

PubMed2001

Measurement of the lambda(+)(c) lifetime.

The Lambda+c lifetime is measured using 9.0 fb(-1) of e+e- annihilation data collected on or just below the Upsilon(4S) resonance with the CLEO II.V detector at CESR. Using an unbinned maximum likelihood fit, the Lambda+c lifetime is measured to be 179.6+/-6.9(stat)+/-4.4(syst) fs. The precision of this colliding beam measurement is comparable to other measurements, which are based on fixed-target experiments, with different systematic uncertainties.

Journal Article↗

PubMed2001

AIDS epidemic at the beginning of the third millennium: time for a new AIDS vaccine strategy.

Current expansion of AIDS pandemic significantly accelerates AIDS vaccine research resulting in development and clinical testing of several AIDS vaccine candidates. At the same time, available experimental and clinical data demonstrate that current AIDS vaccine strategy is unsuccessful resulting in development of inefficient and harmful vaccines. This overview briefly summarizes reported results which point out the requirement for moratorium on the current clinical trials of HIV-1 gp120/160 vaccines and urgent need for development of a new, efficient and safe AIDS vaccine strategy.

AIDS Vaccines↗

PubMed2001

Dynamin, encoded by shibire, is central to cardiac function.

Employing the Drosophila heart, a model system for genetic and molecular investigation of cardiac physiology, we demonstrate here an essential role for the protein dynamin, encoded by the Drosophila gene shibire(ts) (shi(ts)), in maintaining normal heart function. In flies bearing two temperature-sensitive alleles of shi, shi(ts1) and shi(ts2), heartbeat is both slower and less rhythmic than in wild-type animals. Serotonin and norepinephrine, normally cardioacceleratory in wild type, are without effect in flies bearing the shi mutation. Electrocardiogram (EKG) analysis reveals a bigeminal beat in mutant hearts, unlike the single electrical pulse in wild-type. The gene no action potential (temperature sensitive), with previously-described cardiac aberrations similar to those of shi, interacts with shi: shi/shi;nap/nap mutants have almost wild-type heart function. J. Exp. Zool. 289:81-89, 2001.

Animals↗

PubMed2001

[Functional outcome after reservoir surgery in ulcerative colitis].

BACKGROUND: The aim of this study was to examine whether the functional result of restorative proctocolectomy for ulcerative colitis deteriorated by postponing follow-up from three to eight years after pouch surgery. MATERIAL AND METHODS: All patients (n = 58) operated for ulcerative colitis from 1984-97, who still had intact reservoir, responded to a questionnaire on defecating pattern, stool leakage, perianal irritation, urinary function, workload, sexual life, social life, and the patient's opinion on outcome. The results for the first 29 patients were compared to last 29 patients operated. Median follow-up was eight for the first 29 patients and three years for the last 29. RESULTS: There were no significant difference in functional outcome and patient opinion after pouch surgery between the first 29 and last 29 patients (n = 58). Respective figures for median 24-hour stool frequency were 7.0 and 6.3, leakage of stool 48% and 38%, ability to defer defecation 86% and 97%, perianal irritation 59% and 48%, use of antidiarrhoeal medication 55% and 52%, and wearing of pad 28% and 38%. Sexual life (n = 57) had improved for 11 (19%) and deteriorated for seven patients (12%). Potency was reduced in five (15%) and ejaculation in four patients (12%), one of whom (3%) had retrograde ejaculation. Three (5%) had received a disability pension and five (9%) had reduced workload. After the pouch operation 48 (91%) felt better and three (6%) felt worse because of frequent bowel emptying (n = 3), perianal eczema (n = 1) and pouch fistula (n = 1). INTERPRETATION: The results do not demonstrate any significant deterioration of functional outcome after pouch surgery for ulcerative colitis by postoperative increase of follow-up from three to eight years.

Adolescent↗

PubMed2001

Designing Web-based telemedicine training for military health care providers.

BACKGROUND: The purpose of the study was to ascertain those learning objectives that will initiate increased use of telemedicine by military health care providers. Telemedicine is increasingly moving to the center of the health care industry's service offerings. As this migration occurs, health professionals will require training for proper and effective change management. The United States Department of Defense (DoD) is embracing the use of telemedicine and wishes to use Web-based training as a tool for effective change management to increase use. This article summarizes the findings of an educational needs assessment of military health care providers for the creation of the DoD Web-based telemedicine training curriculum. METHODS: Forty-eight health care professionals were interviewed and surveyed to capture their opinions on what learning objectives a telemedicine training curriculum should include. RESULTS: Twenty learning objectives were found to be needed in a telemedicine training program. These 20 learning objectives were grouped into four learning clusters that formed the structure for the training program. In order of importance, the learning clusters were clinical, technical, organizational, and introduction to telemedicine. FINDINGS: From these clusters, five Web-based modules were created, with two addressing clinical learning needs and one for each of the other learning objective clusters.

Curriculum↗

PubMed2001

A (1-->4)-beta-mannan-specific monoclonal antibody and its use in the immunocytochemical location of galactomannans.

Galactomannan was coupled to a protein carrier for the preparation of monoclonal antibodies. The monoclonal antibodies generated bound to galactomannans from different sources as well as to glucomannan and galactoglucomannan. One monoclonal antibody, BGM C6, was characterised and found to be specific for (1-->4)-beta-linked mannopyranosyl residues; it had a binding affinity estimated at 1x10(-6) M for the (1-->4)-beta-linked mannohexaose. BGM C6 was used in immunogold labelling studies to locate galactomannans in the endosperm walls of normal coconuts (Cocos nucifera L.) and those of the mutant makapuno at two different developmental stages. The pattern and intensity of antibody labelling varied for each type of coconut at the mature and immature stages, indicating differences in the galactomannan composition of the endosperm walls.

Antibodies, Monoclonal↗

PubMed2001

Chlortetracycline modulates acute phase response of ex vivo perfused pig livers, and inhibits TNF-alpha secretion by isolated Kupffer cells.

Tetracyclines have been shown to have anti-inflammatory effects in addition to their antimicrobial action. We investigated the effects of in vivo administration of chlortetracycline (CTC) on ex vivo perfused pig livers. The retention and clearance of Salmonella choleraesuis, production of acute phase proteins C-reactive protein (CRP), and haptoglobin (HPG) by whole livers were studied. The in vitro modulation by CTC of TNF-alpha secretion by pig Kupffer cells (KC) was also studied. Pigs were dosed orally with CTC for three days, and given injections of Salmonella LPS 24 h before removal of the liver. Salmonella retention and clearance by livers of pigs given CTC was lower than by control livers (p < 0.01 and p < 0.05, respectively). We demonstrated an increase of CRP and HPG by livers from control pigs after a three-hour perfusion while pigs from CTC pretreated pigs varied in this response. Further, CTC decreased the secretion of TNF-alpha by cultured KC incubated in vitro with LPS. Modulation of TNF-alpha production by CTC suggests a potential for attenuating the inflammatory response. However, this possible beneficial action of CTC was accompanied by a significant decline in the antimicrobial effect of the liver.

Acute-Phase Reaction↗

PubMed2001

Forced expression of the cyclin-dependent kinase inhibitor p16(INK4A) in leukemic U-937 cells reveals dissociation between cell cycle and differentiation.

OBJECTIVE: The aim of this study was to investigate how the tumor suppressor protein p16(INK4A) interferes with growth and differentiation of leukemic U-937 cells. MATERIALS AND METHODS: U-937 clones constantly overexpressing the cyclin-dependent kinase inhibitor p16(INK4A) were established. Clones transfected with empty vector were used as controls. The effects of high-level expression of p16(INK4A) on proliferation and cell cycle progression were investigated (cell cycle distribution, proliferation rate, analyses of different cell cycle regulatory proteins). The effect of introduction of p16(INK4A) on capacity for induced differentiation, assayed by capacity to reduce nitroblue tetrazolium, was determined. RESULTS: Overexpressed p16(INK4A) protein was active as judged by its ability to bind to CDK-4 in a coimmunoprecipitation assay. Clones overexpressing p16(INK4A) grew slower than controls, without any apparent effects on the phosphorylation status of the retinoblastoma protein (pRb). Instead, p16(INK4A) overexpression affected the phosphorylation status of pRb-related pocket protein p130, which was detected in its growth-restraining hypophosphorylated form. Despite an enhanced tendency to accumulate in G(0)/G(1), p16(INK4A)-overexpressing cells were less sensitive to induction of differentiation with vitamin D(3) or ATRA than control cells. CONCLUSIONS: Constitutive expression of p16(INK4A) in U-937 cells resulted in decreased proliferation as a result of activated p130 rather than pRb. Also, we showed that introduction of p16(INK4A) into U-937 cells impaired their capacity to differentiate. Moreover, the results support the notion that cell differentiation and cell cycle progression are dissociated and independently regulated processes.

Cell Cycle↗

PubMed2001

Effects of C5a and FMLP on interleukin-8 production and proliferation of human umbilical vein endothelial cells.

Interleukin-8 (IL-8), C5a and N-formyl-methionyl-leucyl-phenylalanine (fMLP) are chemotactic peptides with predominant effects on leukocytes during inflammation. With emphasis on C5a we studied the regulation of the production of IL-8 by human umbilical vein endothelial cells (HUVEC) in vitro. Primary HUVEC cultures were incubated with IL-1alpha, TNFalpha, C5a and fMLP for 24 h and 48 h prior to measurement of IL-8 in supernatants of the cells by an enzyme immunoassay. Whereas IL-1alpha and TNFalpha significantly increased the levels of IL-8, C5a decreased the IL-8 production after 48 h. In addition, the ability of IL-1alpha, TNFalpha, C5a, fMLP and IL-8 to induce cell proliferation was compared by means of a 3H-thymidine incorporation assay. In contrast with IL-1alpha and TNFalpha, both C5a and fMLP increased cell proliferation of HUVEC. This increase occurred with increasing concentrations of C5a contrary to IL-8, which showed increased cell proliferation at low, but not high IL-8 concentrations.

Cell Division↗

PubMed2001

Adolescent illegal drug use: the impact of personality, family, and environmental factors.

This study examined the relationship between the domains of environmental factors, family illegal drug use, parental child-rearing practices, maternal and adolescent personality attributes, and adolescent illegal drug use. A nonclinical sample of 2,837 Colombian youths and their mothers were interviewed about intrapersonal, interpersonal, and environmental factors in their lives. Results indicated that certain environmental factors (e.g., violence, drug availability, and machismo), family drug use, a distant parent-child relationship, and unconventional behavior are risk factors for adolescent illegal drug use. As hypothesized, results showed that the adverse effects of family illegal drug use on adolescent drug use can be buffered by protective parental child-rearing practices and environmental factors, leading to less adolescent illegal drug use. Prevention and treatment efforts should incorporate protective environmental, familial, and intrapersonal components in order to reduce adolescent illegal drug use.

Adolescent↗

PubMed2001

Stress in UK families conducting intensive home-based behavioral intervention for their young child with autism.

There is increasing international interest in intensive home-based behavioral intervention for children with autism. In the present study, 141 UK parents conducting such interventions completed a questionnaire addressing issues of stress, coping, and support. Regression analyses showed that parents' stress levels were predicted mainly by psychological rather than demographic variables. In particular, adaptive coping strategies, informal social support sources, and beliefs about the efficacy of the intervention were associated with lower reported stress and higher levels of autism symptomatology were associated with higher reported stress. There was also evidence that the use of Passive Appraisal coping and beliefs about the efficacy of the interventions moderated the effects of autism symptomatology on parents' pessimism. Implications of these findings for future research and for the support of families engaged in intensive home-based behavioral intervention are discussed.

Adaptation, Psychological↗

PubMed2001

Molecular characterization of a myelodysplasia-associated chromosome 7 inversion.

Chromosome 7 abnormalities are observed in a wide range of myeloid disorders, particularly myelodysplasia (MDS) and acute myeloid leukaemia (AML). Monosomy 7 and 7q deletions are the most frequent abnormalities, although translocations and inversions involving 7q also occur. The region 7q22--q34 may contain as many as four distinct minimal regions of deletion (MDRs), which are thought to contain one or more myeloid tumour-suppressor genes. We have defined previously the proximal breakpoint of a constitutional 7q22--q34 inversion, carried in a cell line derived from a member of a family with a history of MDS. A YAC clone spanning this breakpoint was identified. Both inversion breakpoints have now been cloned and sequenced, placing the proximal breakpoint 40 kb centromeric to the TAC2 (tachykinin 2) gene and the distal breakpoint 42 kb telomeric to the SSBP (mitochondrial single-stranded DNA-binding protein) gene. Sequence alignments revealed small (3--4 bp) duplications at the inversion breakpoints, suggesting that the mechanism of inversion involved the creation of staggered breaks and filling in of the overhanging ends. A 190-bp Alu--Alu deletion close to the distal breakpoint was also detected and may have contributed to the inversion.

Autoradiography↗

PubMed2001

Elevated antibody responses in patients with Crohn's disease against a 14-kDa secreted protein purified from Mycobacterium avium subsp. paratuberculosis.

Patients with Crohn's disease (CD) (n = 10) and ulcerative colitis (UC) (n = 10) were tested for immune responses against various antigens from Mycobacterium avium subsp. paratuberculosis; alkyl hydroperoxide reductase C (AhpC) and alkyl hydroperoxide reductase D (AhpD), which are constitutively expressed in this species as opposed to other mycobacteria, a 14-kDa secreted antigen and PPD-J. The CD patients had significantly elevated antibody levels against the 14 kDa protein (P < 0.05) that were negatively correlated with the duration of the disease (r(s) = - 0.85). They also seemed to have increased antibody levels against AhpC and AhpD, but the differences between the two groups were not significant. However, taken together, the antibody responses to three individual mycobacterial antigens in CD patients strengthen the possibility that the observed responses are caused by mycobacterial infection. No significant differences in the interferon (IFN)-gamma production, the interleukin (IL)-10 production and the ability to proliferate upon stimulation with these antigens were observed. These results show that measuring antibody responses against purified specific antigens is a suitable and simple approach when assessing the connection between CD and mycobacteria in patients with clinical CD. Another important aspect in such studies is to have well defined patient groups tested at the onset of clinical symptoms.

Adult↗