Biomedical subjects

Robert Kennedy

Publications and source records attributed to Robert Kennedy.

6 recordsLinked to original sources

PubMed2006

In vitro characterization of the interaction between HIV-1 Gag and human lysyl-tRNA synthetase.

Human immunodeficiency virus type 1 (HIV-1) viral assembly is mediated by multiple protein-protein and protein-nucleic acid interactions. Human tRNA(Lys3) is used as the primer for HIV reverse transcription, and HIV Gag and GagPol are required for packaging of the tRNA into virions. Human lysyl-tRNA synthetase (LysRS) is also specifically packaged into HIV, suggesting a role for LysRS in tRNA packaging. Gag alone is sufficient for packaging of LysRS, and these two proteins have been shown to interact in vitro using glutathione S-transferase pull-down assays. In vitro pull-down assays using truncated constructs have also revealed that residues important for homodimerization of Gag and LysRS are critical for the Gag/LysRS interaction. In this work, we report further in vitro characterization of the interaction between HIV Gag and human LysRS using affinity pull-down assays, fluorescence anisotropy measurements and gel chromatography. An equilibrium binding constant of 310 +/- 80 nM was measured for the Gag/LysRS interaction. We also show that capsid alone binds to LysRS with a similar affinity as full-length Gag. Point mutations that disrupt the homodimerization of LysRS and Gag in vitro do not affect their interaction. These results suggest that dimerization of each protein per se is not required for the interaction but that residues involved in forming the homodimer interfaces contribute to heterodimer formation. Gel chromatography studies further support the formation of a Gag/LysRS heterodimer.

Anisotropy↗

PubMed2004

A comparison of buffered lidocaine versus ELA-Max before peripheral intravenous catheter insertions in children.

BACKGROUND: Peripheral intravenous catheter (PIV) insertion is a common, painful experience for many children in the pediatric emergency department. Although local anesthetics such as injected buffered lidocaine have been shown to be effective at reducing pain and anxiety associated with PIV insertion, they are not routinely used. ELA-Max, a topical local anesthetic, has the advantage of needle-free administration but has not been compared with buffered lidocaine for PIV insertion. OBJECTIVE: To compare the reduction of pain and anxiety during PIV insertion provided by subcutaneous buffered 1% lidocaine or topical ELA-Max in children. METHODS: A randomized trial in children 4 to 17 years old undergoing PIV insertion with 22-gauge catheters was conducted. Children received either buffered lidocaine or ELA-Max. Buffered lidocaine was administered by using 30-gauge needles to inject 0.1 to 0.2 mL subcutaneously just before PIV insertion. ELA-Max was applied to the skin and occluded with Tegaderm 30 minutes before PIV insertion. Self-reported Visual Analog Scale (VAS) questionnaires (rating on a scale of 1-10; 1 = no pain, anxiety) were completed by patients and their parents before PIV insertion to assess baseline perceptions about pain and anxiety associated with PIV insertion and immediately after PIV insertion to assess pain and anxiety associated with the experience. After PIV insertion, the nurse who inserted the PIV also completed a VAS questionnaire assessing technical difficulty and satisfaction with the local anesthesia. A blinded observer also completed a VAS questionnaire to assess pain and anxiety associated with the PIV insertion. Data were analyzed by using chi2 and t tests. RESULTS: Sixty-nine subjects were enrolled, and questionnaires were competed by all (mean age: 12.1 +/- 4.5 years; 61% female). There were no differences for buffered lidocaine and ELA-Max groups in age, gender, race, prior IV experience, or baseline pain and anxiety. There were no significant differences between buffered lidocaine and ELA-Max in mean pain and anxiety after PIV insertion by patient, parent, and blinded observer ratings. Nurse ratings of technical difficulty, number of PIV-insertion attempts, and satisfaction with local anesthesia also were not significantly different for buffered lidocaine and ELA-Max groups. CONCLUSIONS: ELA-Max provided similar pain and anxiety reduction during PIV insertion in children compared with injected buffered lidocaine. Technical difficulty and satisfaction by nurses inserting the PIV also were similar.

Administration, Topical↗

PubMed2003

Cognitive effects of dexamethasone at high altitude.

OBJECTIVE: The major therapeutic effect of dexamethasone on persons affected by high-altitude illness may be upon vascular leakiness with a consequent decrease in cerebral edema. We set out to determine if dexamethasone ameliorates the cognitive/psychomotor effects of acute exposure to high altitude on asymptomatic subjects. METHODS: Six adult subjects were tested at baseline (2500 m) with standard, computerized cognitive and psychomotor tests. Over the next 4 days, subjects were acclimatized to an altitude of 3700 m. On the fifth day, subjects ascended to 4800 m where predexamethasone testing was administered. No subject had symptoms of frank altitude illness at 4800 m. To limit acclimatization, subjects descended to 3700 m within 4 hours. The first 4-mg dose of oral dexamethasone was given in the evening of day 5. A second 4-mg dose of dexamethasone was given the following morning, and subjects reascended to 4800 m where postdexamethasone testing was performed. RESULTS: All cognitive and psychomotor tests showed improved reaction times in subjects who were given dexamethasone. Mean reaction time (+/- SD) for shape recognition went from 1.20 +/- 0.36 seconds at 2500 m to 1.40 +/- 0.37 seconds at 4800 m. After dexamethasone administration, mean shape recognition time declined to 1.26 +/- 0.32 seconds (P = .052). CONCLUSION: These data show a trend toward decreased cognitive deficits in subjects pretreated with dexamethasone. One possibility for this trend is that cognitive deficits in otherwise asymptomatic subjects exposed to high altitude are caused by subclinical cerebral edema.

Administration, Oral↗

PubMed2002

Detection and imaging of zinc secretion from pancreatic beta-cells using a new fluorescent zinc indicator.

A novel Zn2+-selective visible wavelength fluoroionophore (FluoZin-3, 9) was synthesized. The chelating portion of the molecule resembles known EGTA-based Ca2+-selective fluoroionophores, except that one of the N-acetic acid moieties has been deleted in 9. FluoZin-3 is virtually non-fluorescent in the absence of Zn2+, and exhibits a several hundred-fold fluorescence increase upon saturation with Zn2+( approximately 100 nM), with a Kd = 15 +/- 2 nM. A 1:1 binding stoichiometry of 9:Zn2+ was determined, and the fluorescence of the complex is pH-independent at pH > 6. FluoZin-3 was used to monitor Zn2+ that was co-secreted with insulin from pancreatic beta-cells by exocytosis following stimulation with glucose. The total Zn2+ concentration near the cells reached 600 nM, and Zn2+ was detectable at least 15 mum away from secreting cells. Heterogeneity in secretion among cells was indicated in that some cells in a cluster did not release Zn2+. Also, within secreting cells some regions of the cell membrane gave rise to secretion while others did not, suggesting active zones of secretion on the cell surface.

Cations, Divalent↗

PubMed2002

Blindness and glaucoma: a comparison of patients progressing to blindness from glaucoma with patients maintaining vision.

PURPOSE: To compare patients becoming legally blind from glaucoma with those who did not go blind. DESIGN: Retrospective, cohort, and case-control study. METHODS: A retrospective community-based longitudinal study of residents of Olmsted County, Minnesota, who were newly diagnosed with open-angle glaucoma between 1965 and 1980 and followed through 1998. A case-control study was performed comparing patients progressing to legal blindness from glaucoma with aged-matched and visual field-matched patients not progressing to blindness. RESULTS: Fifty-six of 290 patients progressed to legal blindness in at least one eye over the 34-year period of the study. Most who progressed to blindness had moderate to advanced visual field loss at the time of diagnosis of glaucoma. Those becoming legally blind had mean intraocular pressures (IOP) on therapy lower than or similar to patients who did not go blind, although the variability of IOP was higher in the blind group. Different susceptibilities to IOP were apparent, as some eyes with initially normal disks and visual fields became blind at an IOP of 20 mm, while others did not worsen. Changes in medical therapy after progression of visual field damage were less effective in lowering IOP in the group becoming blind than in the nonblind group. CONCLUSIONS: Patients at greatest risk of blindness had visual field loss at the time of diagnosis of glaucoma. Different susceptibilities to IOP were apparent, with some patients becoming blind at pressures that others tolerated without significant progression. This suggests that continued monitoring of visual fields and reassessment of target IOP levels when field damage occurs are fundamental in the management of glaucoma.

Aged↗

PubMedDate not supplied

Controlling contagious bacterial conjunctivitis.

BACKGROUND: Recent outbreaks (epidemics) of Streptococcus pneumoniae conjunctivitis, involving hundreds of patients, underscore the importance of following recommended guidelines to minimize disease transmission. These include the use of antimicrobial agents capable of minimizing patients' symptoms and the duration of the infectious period when disease can be transmitted to others. PURPOSE: To compare the amount of time required forvarious antibiotic solutions to kill S. pneumoniae, a common cause of bacterial conjunctivitis. MATERIALS AND METHODS: Isolates of S. pneumoniae from three patients were exposed to selected ophthalmic antibiotic products: moxifloxacin 0.5%, tobramycin 0.3%, gentamicin 0.3%, and polymyxin B 10,000 IU-trimethoprim 1.0%. The products were diluted 1:100 and 1:1000 for testing. At 15, 30, 60, 120, and 180 minutes after exposure, aliquots of broth were withdrawn, the cells were separated and cultured, and the viable cell count was determined. RESULTS: Moxifloxacin killed actively growing S. pneumoniae faster and to a greater extent than did the other three antibiotic products when tested at concentrations corresponding to tear film concentrations 5 to 10 minutes and 30 to 60 minutes after instillation of the products. CONCLUSIONS: Moxifloxacin killed S. pneumoniae in vitro faster than did the other antibiotics. Consequently, its use should complement other generally accepted measures for minimizing patients' symptoms and limiting the contagiousness of bacterial conjunctivitis. Also, this is consistent with the recommendations of other investigators to prescribe the most recent generation of fluoroquinolone antibiotics for the specific purpose of limiting the spread of bacterial resistance.

Anti-Bacterial Agents↗