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J Ernst

Publications and source records attributed to J Ernst.

At least 55 records · Page 3Linked to original sources
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

Precision grip deficits in cerebellar disorders in man.

OBJECTIVE: To investigate the effect of a variety of cerebellar pathologies on a functional motor task (lifting an object in a precision grip). METHODS: The study involved 8 patients with unilateral damage in the region of the posterior inferior cerebellar artery (PICA), 6 with damage in the region of the superior cerebellar artery (SUPCA), 12 patients with familiar or idiopathic cortical cerebellar degeneration, and 45 age-matched normal subjects. Subjects lifted an object of unpredictable load (internally guided task) or responded to a sudden load increase while holding the object steadily (externally guided task). RESULTS: Damage to the dentate nucleus (SUPCA) or its afferent input (cerebellar atrophy) resulted in disruption of the close coordination normally seen between proximal muscles (lifting the object) and the fingers (gripping the object) during a self-paced lift. Both the SUPCA group and, more markedly, the atrophy group, showed exaggerated levels of grip force. All patients showed a normal rate of grip force development. Damage in the PICA region had no significant effect on any of the measured lifting parameters. All patient groups retained the ability to scale grip force to different object loads. The automatic grip force response to unexpected load increase of a hand held object showed normal latency and time course in all patient groups. The response was modulated by the rate of the load change. Response magnitude was exaggerated in the atrophy patients at all 3 rates tested. CONCLUSIONS: Disturbances associated with cerebellar disorders differed from those seen following damage to the basal ganglia, with no evidence of slowed rates of grip force development. Disruption of temporal coordination between the proximal muscles (lifting) and the fingers (gripping) in a lift was apparent, supporting the role of the cerebellum in coordinating the timing of multi-joint movement sequences. Exaggeration of grip force levels was found in association with damage to the dentate nucleus or, in particular, to its afferent input. This could support a role or the cerebellum in sensorimotor processing, but might also represent a failure to time correctly the duration of grip force generation.

Action Potentials↗
PubMed2000

Measurements of the mass, total width, and two-photon partial width of the eta(c) meson.

Using 13.4 fb(-1) of data collected with the CLEO detector at the Cornell Electron Storage Ring, we have observed 300 events for the two-photon production of ground-state pseudoscalar charmonium in the decay eta(c)-->K(0)(S)K-/+pi(+/-). We have measured the eta(c) mass to be [2980.4+/-2.3 (stat)+/-0.6 (syst)] MeV and its full width as [27.0+/-5.8 (stat)+/-1.4 (syst)] MeV. We have determined the two-photon partial width of the eta(c) meson to be [7.6+/-0.8 (stat)+/-0.4 (syst)+/-2.3 (br)] keV, with the last uncertainty associated with the decay branching fraction.

Journal Article↗
PubMed2000

Study of exclusive radiative B meson decays

We have studied exclusive, radiative B meson decays to charmless mesons in 9.7x10(6) B&Bmacr; decays accumulated with the CLEO detector. We measure B(B0-->K(*0)(892)gamma) = (4.55(+0.72)(-0. 68)+/-0.34)x10(-5) and B(B+-->K(*+)(892)gamma) = (3.76(+0.89)(-0. 83)+/-0.28)x10(-5). We have searched for CP asymmetry in B-->K(*)(892)gamma decays and measure A(CP) = +0.08+/-0.13+/-0.03. We report the first observation of B-->K(*)(2)(1430)gamma decays with a branching fraction of (1.66(+0.59)(-0.53)+/-0.13)x10(-5). No evidence for the decays B-->rhogamma and B0-->omegagamma is found and we limit B(B-->(rho/omega)gamma)/B(B-->K(*)(892)gamma)<0.32 at 90% C.L.

Journal Article↗
PubMed2000

Search for the decay &Bmacr;(0)-->D(*0)gamma

We report results of a search for the rare radiative decay &Bmacr;(0)-->D(*0)gamma. Using 9.66x10(6) B&Bmacr; meson pairs collected with the CLEO detector at the Cornell Electron Storage Ring, we set an upper limit on the branching ratio for this decay of 5.0x10(-5) at 90% C.L. This provides evidence that the anomalous enhancement is absent in W-exchange processes and that weak radiative B decays are dominated by the short-distance b-->sgamma mechanism in the standard model.

Journal Article↗
PubMed2000

A European multicentric experience using the CardioSEal and Starflex double umbrella devices to close interatrial communications holes within the oval fossa.

In this review, we describe the experience from 13 European centres using the CardioSEAL and Starflex double umbrella devices to close interatrial communications within the oval fossa (so-called 'secundum' defects). Between October 1996 and April 1999, the procedure was attempted in 334 patients with a mean age of 12 years and a mean weight of 44kg. The mean measured stretched diameter of the defect was 15 mm. In the overall group, the defect was solitary in 245 patients (73%), multiple in 21 (6%), associated with an aneurysm of the flap valve in 15 (5 %), was represented by patency of the oval foramen in 44 (13%), and was a fenestration in a Fontan repair in 9 (3%). In all patients, the devices were inserted under general anesthesia, using fluoroscopic and transesophageal echocardiographic control. Implantation was achieved in 325 (97,3%). The device embolized within either a few minutes or a few hours in 13 patients (4%). Of these, uncomplicated surgical repair was undertaken in 10, while the device was retrieved in 3 using catheters and a second device was successfully implanted. Residual shunting was detected immediately after the procedure in 41% of the patients, with the incidence decreasing to 31% at discharge, 24% at 1 month, 21% at 6 months, and 20.5% at one year. During the period of follow-up, elective surgical repair became necessary in two patients, due to malposition of the device in one, and late embolization in the other. Fractures of arms were seen in 6.1 %, most commonly with the largest devices. All those with fractured arms of the device were asymptomatic, and no clinical complications related to the fractures were observed. There were no arrhythmias, endocarditis, valvar distortion, thromboembolic events, or other complications. After one year of follow-up, clinical success, defined as complete closure of the defect or presence of only a trivial leak, had been obtained in 92.5% of the patients. We conclude, therefore, that these devices produce excellent results when used to close defects of small to moderate size. Results are less than optimal, or else complications ensure, when attempts are made to close very large defects.

Adolescent↗
PubMed2000

Morphogenesis, adhesive properties, and antifungal resistance depend on the Pmt6 protein mannosyltransferase in the fungal pathogen candida albicans.

Protein mannosyltransferases (Pmt proteins) initiate O glycosylation of secreted proteins in fungi. We have characterized PMT6, which encodes the second Pmt protein of the fungal pathogen Candida albicans. The residues of Pmt6p are 21 and 42% identical to those of C. albicans Pmt1p and S. cerevisiae Pmt6p, respectively. Mutants lacking one or two PMT6 alleles grow normally and contain normal Pmt enzymatic activities in cell extracts but show phenotypes including a partial block of hyphal formation (dimorphism) and a supersensitivity to hygromycin B. The morphogenetic defect can be suppressed by overproduction of known components of signaling pathways, including Cek1p, Cph1p, Tpk2p, and Efg1p, suggesting a specific Pmt6p target protein upstream of these components. Mutants lacking both PMT1 and PMT6 are viable and show pmt1 mutant phenotypes and an additional sensitivity to the iron chelator ethylenediamine-di(o-hydroxyphenylacetic acid). The lack of Pmt6p significantly reduces adherence to endothelial cells and overall virulence in a mouse model of systemic infection. The results suggest that Pmt6p regulates a more narrow subclass of proteins in C. albicans than Pmt1p, including secreted proteins responsible for morphogenesis and antifungal sensitivities.

Alleles↗
PubMed2000

Modulation of Dengue virus infection in human cells by alpha, beta, and gamma interferons.

A role for interferon (IFN) in modulating infection by dengue virus (DV) has been suggested by studies in DV-infected patients and IFN receptor-deficient mice. To address how IFN modulates DV type 2 infection, we have assayed IFN-alpha, -beta, and -gamma for the ability to enhance or diminish antibody-independent and antibody-dependent cell infection using a competitive, asymmetric reverse transcriptase-mediated PCR (RT-PCR) assay that quantitates positive and negative strands of viral RNA, a flow cytometric assay that measures viral antigen, and a plaque assay that analyzes virion production. Our data suggest that IFN-alpha and -beta protect cells against DV infection in vitro. Treatment of hepatoma cells with IFN-alpha or -beta decreases viral RNA levels greater than 1, 000-fold, the percentage of cells infected 90 to 95%, and the amount of infectious virus secreted 150- to 100,000-fold. These results have been reproduced with several cell types and viral strains, including low-passage isolates. In contrast, IFN-gamma has a more variable effect depending on the cell type and pathway of infection. Quantitative RT-PCR experiments indicate that IFN inhibits DV infection by preventing the accumulation of negative-strand viral RNA.

Animals↗
PubMed1998

Rates of tuberculosis infection in healthcare workers providing services to HIV-infected populations. Terry Beirn Community Programs for Clinical Research on AIDS.

OBJECTIVE: To assess the prevalence of tuberculosis (TB) or a positive skin test in healthcare workers (HCWs) providing services to human immunodeficiency virus (HIV)-infected individuals and to determine prospectively the incidence of new infections in this population. DESIGN: This prospective cohort study enrolled 1,014 HCWs working with HIV-infected populations from 10 metropolitan areas. Purified protein derivative (PPD) tuberculin skin tests were placed at baseline and every 6 months afterwards on those without a history of TB or a positive PPD. Demographic, occupational, and TB exposure data also were collected. SETTING: Outpatient clinics, hospitals, private practice offices, and drug treatment programs providing HIV-related healthcare and research programs. PARTICIPANTS: A voluntary sample of staff and volunteers from 16 Community Programs for Clinical Research on AIDS units. RESULTS: Factors related to prior TB or a positive skin test at baseline included being foreign-born, increased length of time in health care, living in New York City, or previous bacille Calmette-Guerin vaccination. The rate of PPD conversion was 1.8 per 100 person years of follow-up. No independent relation was found between the amount or type of contact with HIV-infected populations and the risk of TB infection. CONCLUSION: These data provide some reassurance that caring for HIV-infected patients is not related to an increased rate of TB infection among HCWs in these settings.

AIDS-Related Opportunistic Infections↗
PubMed1997

Aortic root replacement with human tissue valves in aortic valve endocarditis.

OBJECTIVE: Aortic allograft and pulmonary autograft aortic root replacement in native and prosthetic aortic valve endocarditis are evaluated and risk factors for hospital death are assessed by univariate risk factor analysis. METHODS: From April 1989 to May 1996, 59 patients with aortic valve endocarditis (27 native; 32 prosthetic) underwent aortic root replacement with a human tissue valve. Mean age was 53.4 +/- 12.3 years; 46 patients (78%) were male. The mean preoperative NYHA functional class was 3.4. The predominant infective organisms were streptococci (30%) in the native valve group and staphylococci (30%) in the prosthetic valve group. In native valve endocarditis, valve destruction (32%) was the predominant finding. Abscesses, either annular (29%) or subannular (36%) and valve dehiscence (36%) were the most common findings in patients with prosthetic valve endocarditis. Partial or total ventriculo-aortic discontinuity (20%) and aortico-mitral discontinuity (27%) were other important operative observations. A cryopreserved allograft was used in 53 patients (89.5%), the pulmonary autograft (Ross procedure) in 5 patients (8.5%), and a fresh antibiotic sterilized allograft root in one patient (2%). Mean aortic cross-clamp time was 131 +/- 32 min. In active native and prosthetic valve endocarditis, intravenous antibiotics were continued for at least 6 weeks, monitored by serial CRP measurements. RESULTS: Hospital mortality was 8.5% (n = 5; 70% CL: 4.9-12.1%). Univariate risk factors for hospital mortality were age (P = 0.001), preoperative New York Heart Association functional class (P = 0.001), pre- (P = 0.001) and postoperative (P = 0.001) renal insufficiency. Major complications were allograft failure (n = 1; 2%), technical failure (n = 1; 2%) and false aneurysm formation at the proximal suture line (n = 1; 2%). Follow-up was complete, mean 33.1 +/- 20.1 months. Two late deaths occurred. Actuarial five year survival was 88.8% (70% CL: 80.0-97.5%); actuarial five year freedom from recurrent endocarditis was 98.1% (70% CL: 94.5-100%). CONCLUSION: Allograft aortic root replacement is a valuable technique in the life threatening situations both of native and prosthetic aortic valve endocarditis with involvement of the annular and peri-annular region.

Adult↗
PubMed1997

Presence of human immunodeficiency virus (HIV) type 1 subtype A infection in a New York community with high HIV prevalence: a sentinel site for monitoring HIV genetic diversity in North America. Centers for Disease Control and Prevention-Bronx Lebanon HIV Serosurvey Team.

To determine whether US residents are infected with subtypes of human immunodeficiency virus (HIV) type 1 other than subtype B (Western), the predominant North American subtype with a unique GPGR genetic sequence in the V3 loop, viruses from 22 HIV-infected adults were serotyped and subtyped. Twenty patients had subtype B (Western), of whom 15 had serotype B (Western), 3 had serotype A/C, 1 had serotype B (Thai), and 1 had a nontypeable serotype. Two had subtype A, both serotype A/C. Both subtype A-infected patients, only 1 of whom had been outside the United States, reported sex with persons traveling abroad, suggesting possible acquisition in the United States. Because US residents are infected with non-subtype B (Western) strains, US surveillance for HIV-1 diversity is needed to elucidate subtype-specific transmission patterns and pathogenesis and to guide evaluation and development of HIV diagnostic tests and vaccines.

Adolescent↗
PubMed1997

Localization of five annexins in J774 macrophages and on isolated phagosomes.

Annexins are a family of structurally related proteins which bind phospholipids in a calcium-dependent manner. Although the precise functions of annexins are unknown, there is an accumulating set of data arguing for a role for some of them in vesicular transport and, specifically, in membrane-membrane or membrane-cytoskeletal interactions during these processes. Here we describe our qualitative and quantitative analysis of the localization of annexins I-V in J774 macrophages that had internalized latex beads, both with and without IgG opsonization. Our results show that whereas all these annexins are present on both the plasma membrane and on phagosomes, the localization on other organelles differs. Annexins I, II, III and V were detected on early endosomes, while only annexin V was seen on late endocytic organelles and mitochondria. Annexins I and II distributed along the plasma membrane non-uniformly and co-localized with F-actin at the sites of membrane protrusions. We also investigated by western blot analysis the association of annexins with purified phagosomes isolated at different time-points after latex bead internalization. While the amounts of annexins I, II, III and V associated with phagosomes were similar at all times after their formation, the level of annexin IV was significantly higher on older phagosomes. Whereas annexins I, II, IV and V could be removed from phagosome membranes with a Ca2+ chelator they remained membrane bound under low calcium conditions. In contrast, annexin III was removed under these conditions and needed a relatively high Ca2+ concentration to remain phagosome bound. Because of their purity and ease of preparation we suggest that phagosomes are a powerful system to study the potential role of annexins in membrane traffic.

Animals↗
PubMed1996

Performance characteristics of a rapid HIV antibody assay in a hospital with a high prevalence of HIV infection. CDC-Bronx-Lebanon HIV Serosurvey Team.

BACKGROUND: The delay between collection of blood samples and availability of test results may be as long as 3 weeks and is one barrier to the acceptance of voluntary testing for human immunodeficiency virus (HIV) infection. Serologic tests that provide results rapidly could overcome this barrier, but the accuracy and reliability of rapid tests have not been well characterized in the United States. OBJECTIVE: To evaluate, in a "real world" setting, the performance characteristics of a rapid HIV assay that reduces the need for patients to return for counseling after the test. DESIGN: Testing of HIV antibodies by rapid and nonrapid assays and survey about risk behaviors for HIV. SETTING: A hospital in Bronx, New York, with a high prevalence of HIV-seropositive patients. PATIENTS: 837 patients who were not known to be infected with HIV, had not been admitted for conditions related to the acquired immunodeficiency syndrome, and agreed to participate in HIV testing and an interview. MEASUREMENTS: Sensitivity and specificity of a rapid HIV antibody assay based on comparisons with nonrapid assay and Western blot assay. RESULTS: According to nonrapid assays, 5.4% of patients were infected with HIV. The rapid assay was highly accurate in this sample overall: its sensitivity was 1.00, its specificity was 0.991, its positive predictive value was 0.865, and its negative predictive value was 1.00. The assay was also highly accurate in various subgroups. CONCLUSIONS: Accurate, rapid tests for HIV infection may enhance testing programs by preventing the need for delayed counseling of seronegative patients and by providing preliminary results to seropositive patients. These preliminary results may encourage patients to return for confirmatory test results and to adopt risk-reducing behaviors sooner.

Adolescent↗