Biomedical subjects

J K Becker

Publications and source records attributed to J K Becker.

7 recordsLinked to original sources

PubMed2006

Limits on the high-energy gamma and neutrino fluxes from the SGR 1806-20 giant flare of 27 December 2004 with the AMANDA-II detector.

On 27 December 2004, a giant gamma flare from the Soft Gamma-Ray Repeater 1806-20 saturated many satellite gamma-ray detectors, being the brightest transient event ever observed in the Galaxy. AMANDA-II was used to search for down-going muons indicative of high-energy gammas and/or neutrinos from this object. The data revealed no significant signal, so upper limits (at 90% C.L.) on the normalization constant were set: 0.05(0.5) TeV-1 m;{-2} s;{-1} for gamma=-1.47 (-2) in the gamma flux and 0.4(6.1) TeV-1 m;{-2} s;{-1} for gamma=-1.47 (-2) in the high-energy neutrino flux.

Journal Article↗

PubMed2004

Search for extraterrestrial point sources of neutrinos with AMANDA-II.

We present the results of a search for point sources of high-energy neutrinos in the northern hemisphere using AMANDA-II data collected in the year 2000. Included are flux limits on several active-galactic-nuclei blazars, microquasars, magnetars, and other candidate neutrino sources. A search for excesses above a random background of cosmic-ray-induced atmospheric neutrinos and misreconstructed downgoing cosmic-ray muons reveals no statistically significant neutrino point sources. We show that AMANDA-II has achieved the sensitivity required to probe known TeV gamma-ray sources such as the blazar Markarian 501 in its 1997 flaring state at a level where neutrino and gamma-ray fluxes are equal.

Journal Article↗

PubMed2001

Evaluation of the Neuroscience Nurse Internship Program: the first decade.

This article describes the evaluation of the Neuroscience Nurse Internship Program (NNIP). The NNIP was initiated in 1988 by the National Institutes of Health Clinical Center to meet the demand for highly skilled nurses to care for persons with nervous system disorders. To determine whether the program was meeting its goals, an evaluation component was incorporated into the program. The evaluation process was based on the RSA Model of Continuing Education for nursing. The RSA model consists of four basic components, three of which were included in the assessment of the NNIP--process, content, and outcome. The evaluation revealed that the nurse-interns were satisfied with the lectures and clinical content of the program. Moreover, the nurse-interns improved their knowledge of neuroscience nursing and their confidence in performing neuroscience nursing skills. Information from the evaluation was used to modify the structure of the program and to refine lecture content and clinical requirements.

Adult↗

PubMed2000

The Neuroscience Nurse Internship Program: the description.

This article describes the Neuroscience Nurse Internship Program (NNIP) and its implementation at the National Institutes of Health (NIH) Clinical Center in Bethesda, MD. The program, developed in 1988, is designed to prepare nurses to deliver care to persons with nervous system disorders. The program comprises 6 months of lecture and clinical instruction in the country's most well-known biomedical research center. In order to complete the program, nurse-interns must receive a passing grade of 90% or higher on all written tests and achieve satisfactory completion of all clinical assignments. NNIP is cosponsored by the NIH Clinical Center Nursing Department and the National Institute of Neurological Disorders and Stroke (NINDS). Nurses interested in NNIP may apply by submitting an application and a letter of interest to the Clinical Center Human Resources Department. Evaluation of the program is conducted on a regular basis and consists of both process and outcome assessments.

Curriculum↗

PubMed1989

Production and reversal of the neuromuscular pathology and related signs of zinc deficiency in guinea pigs.

The purposes of this study were to use vocalization and posture as indices of the neuromuscular pathology that develops in zinc-deficient guinea pigs and to determine the rate of depletion before and of repletion after intraperitoneal (IP) zinc therapy. When severe signs of deficiency developed, tissues were analyzed for their zinc content to assess sites of depletable and mobilizable zinc stores. Weanling guinea pigs were fed low (less than 1 mg/kg) and adequate (100 mg/kg) zinc diets based on isolated soybean protein or autoclaved egg white. The first signs (stage 1) of vocalization due to handling, abnormal posture and skin lesions developed after approximately 4 wk. Severe (stage 3) signs followed after 5-6 wk. A single IP dose of ZnSO4 (50 mumol/kg) caused remission of signs within 4-5 d following which all signs regressed to stage 3 within 7 d. Analysis of 15 tissues from severely deficient guinea pigs showed that only plasma and bone had significantly lower zinc concentrations than tissues from comparable age-related controls fed a zinc-adequate diet. It seems unlikely that major soft tissues, such as muscle, brain, liver and skin, serve as mobilizable stores of zinc for other critical metabolic functions. Bone zinc is slowly mobilized but at a rate insufficient to maintain health or even life.

Animals↗

PubMed1989

Differential diagnosis of malignant melanoma.

The incidence of malignant melanoma is rising. Early recognition and surgical treatment give the best chance for a cure. Since a variety of skin tumors and conditions may resemble melanoma, knowledge of the differential diagnosis and a systematic approach to the evaluation of a suspicious lesion are essential.

Diagnosis, Differential↗

PubMed1984

High affinity, calcium-stimulated adenosine triphosphatase activity in the particulate fraction of rat pancreatic acini.

Adenosine triphosphatase activity which is Mg2+-dependent and stimulated by submicromolar concentrations of Ca2+ (as Ca . ATP) was identified in the total particulate fraction of rat pancreatic acini. Half-maximal activity (V0.5) is obtained at 100.1 +/- 6 nM Ca . ATP with a Hill coefficient of 2.2 +/- 0.1 (mean +/- S.E.; n = 4). Maximal activity was 75 +/- 19 pmol of Pi released from ATP minute-1 microgram of membrane protein-1 (mean +/- S.E.; n = 7). High affinity Ca2+-ATPase activity was unaffected by ouabain, Na+, K+, La3+, and added calmodulin. Activity was slightly reduced by ruthenium red (0.1 mM) and by oligomycin (80 micrograms/ml) but was reduced almost 50% by the phenothiazine derivative fluphenazine in a dose-related and Ca2+-dependent manner. Hydrolysis of p-nitrophenyl phosphate was 9% of the rate of ATP hydrolysis and was independent of Ca2+ concentration. However, ADP, GTP, UTP, and ITP were hydrolyzed at 76-93% the rate that ATP was hydrolyzed with V0.5 values and Hill coefficients similar to those of Ca . ATP. We conclude that rat pancreatic acini contain an enzyme for active Ca2+ translocation: ATPase activity that is Mg2+-dependent and stimulated by submicromolar concentrations of Ca . ATP. Substrate hydrolysis appears to involve positive cooperative interactions of multiple ligand-binding sites and may be regulated in part by calmodulin.

Adenosine Triphosphate↗