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Biomedical subjects

K Willard

Publications and source records attributed to K Willard.

10 recordsLinked to original sources
PubMed2001

Stability of a second-generation cephalosporin veterinary mastitis formulation after electron beam irradiation.

This study focused on the chemical stability of the cephalosporin (6R, 7R)-7-(1-pentafluorophenoxyacetamido)-3-[2-(5-methyl-1,3,4-thiodiazolyl)thiomethyl]-Delta(3)-cephem-4-carboxylic acid, sodium salt (cephem 1) formulation after electron beam (e-beam) irradiation. The cephem 1 concentrations of samples irradiated at 5, 10, and 15 kilograys for glass vials and low-density polyethylene (LDPE) cannula syringes were not statistically different from the concentrations of the nonirradiated control samples. Samples from each irradiation dose stored in controlled-temperature chambers at 5 degrees C and 30 degrees C for 24 months did not show any concentration changes within statistical limits compared with the nontreated samples. Samples from each irradiation dose stored at 40 degrees C for 12 months also did not show any concentration changes within statistical limits compared with the nontreated samples. The percentage of related substances increased slightly with the increase in e-beam irradiation level and storage temperature, but this increase was within the proposed label claim of 90% to 110% (45-55 mg/g). In conclusion, e-beam sterilization did not affect the chemical stability of cephem 1 intramammary formulation in LDPE cannula syringes, suggesting that e-beam irradiation may be a feasible method for terminal sterilization of this cephem 1 formulation.

Animals↗
PubMed2001

Role of anterior temporal cortex in auditory sentence comprehension: an fMRI study.

Recent neuropsychological and functional imaging evidence has suggested a role for anterior temporal cortex in sentence-level comprehension. We explored this hypothesis using event-related fMRI. Subjects were scanned while they listened to either a sequence of environmental sounds describing an event or a corresponding sentence matched as closely as possible in meaning. Both types of stimuli required subjects to integrate auditory information over time to derive a similar meaning, but differ in the processing mechanisms leading to the integration of that information, with speech input requiring syntactic mechanisms and environmental sounds utilizing non-linguistic mechanisms. Consistent with recent claims, sentences produced greater activation than environmental sounds in anterior superior temporal lobe bilaterally. A similar speech > sound activation pattern was noted also in posterior superior temporal regions in the left. Envirornmental sounds produced greater activation than sentences in right inferior frontal gyrus. The results provide support for the view that anterior temporal cortex plays an important role in sentence-level comprehension.

Adult↗
PubMed1998

Acquisition of Clostridium difficile and Clostridium difficile-associated diarrhea in hospitalized patients receiving tube feeding.

BACKGROUND: Clostridium difficile is the most common infectious cause of nosocomial diarrhea, but its role in diarrhea associated with tube feeding has not been rigorously investigated. OBJECTIVE: To determine the incidence of C. difficile acquisition and C. difficile-associated diarrhea in tube-fed and non-tube-fed patients. DESIGN: Prospective cohort study. SETTING: A university-affiliated Veterans Affairs Medical Center. PATIENTS: 76 consecutive hospitalized, tube-fed patients and 76 hospitalized, non-tube-fed patients. The two cohorts were matched for age, unit location, duration of hospitalization before surveillance, and severity of illness. MEASUREMENTS: Incidence of C. difficile acquisition, incidence of C. difficile-associated diarrhea, and C. difficile restriction endonuclease analysis typing results. RESULTS: More tube-fed patients than non-tube-fed patients acquired C. difficile (15 of 76 patients [20%] compared with 6 of 76 patients [8%]; P=0.03) and developed C. difficile-associated diarrhea (7 of 76 patients [9%] compared with 1 of 76 patients [1%]; P=0.03). The mean proportion (+/-SD) of surveillance days with diarrhea was greater for tube-fed patients after the development of C. difficile-associated diarrhea than for tube-fed patients without this diarrhea (0.68+/-0.4 compared with 0.22+/-0.2 [95% CI for the mean difference, 0.08 to 0.84]). Postpyloric tube feeding (odds ratio, 3.14 [CI, 1.008 to 9.77]) and duration of surveillance (odds ratio, 1.08 [CI, 1.0009 to 1.16]) were risk factors for the acquisition of C. difficile. Nineteen restriction endonuclease analysis types of C. difficile were identified from 20 patients. CONCLUSIONS: Hospitalized, tube-fed patients, especially those receiving postpyloric tube feeding, are at greater risk for the acquisition of C. difficile and the development of C. difficile-associated diarrhea than are hospitalized, non-tube-fed patients. Clinicians should test for C. difficile in tube-fed patients with diarrhea.

Aged↗
PubMed1994

Network analytic methods for epidemiological risk assessment.

The authors measure the efficacy of three methods for predicting the time to infection for susceptible individuals in a population undergoing an HIV epidemic. The methods differ in whether they require detailed information of the contact network and whether they require knowledge of the initial source of infection. Efficacy is evaluated using simulations for 20 different contact patterns. Only the risk score that uses both kinds of information accounts for more than 15 per cent of individual variability. The efficacy of this score ranges from 10 per cent in very unstructured populations to 60 per cent for spatially localized contact networks. This improved performance may be explained by the larger fraction of the total variability not due to the disease dynamics. When all variables are dichotomized, the two poorer methods produce odds ratios between 1.4 and 2.3. The odds ratio for the risk score with full information ranges from 2.5 to 17. Risk assessment protocols and intervention programmes are encouraged to assess contact patterns and detect sources of infection.

Analysis of Variance↗
PubMed1994

Effectiveness of liquid soap vs. chlorhexidine gluconate for the removal of Clostridium difficile from bare hands and gloved hands.

OBJECTIVE: To compare liquid soap versus 4% chlorhexidine gluconate in 4% alcohol for the decontamination of bare or gloved hands inoculated with an epidemic strain of Clostridium difficile. DESIGN: C difficile (6.7 log10 colony-forming units [CFU], 47% spores), was seeded onto bare or latex gloved hands of ten volunteers and allowed to dry. Half the volunteers initially washed with soap and half with chlorhexidine, followed by the other agent 1 week later. Cultures were done with Rodac plates at three sites on the hand: finger/thumbtips, the palmar surfaces of the fingers, and the palm. Statistical comparison was by paired Student's t test. RESULTS: On bare hands, soap and chlorhexidine did not differ in residual bacterial counts on the finger/thumbtips (log10 CFU, 2.0 and 2.1, P = NS) and fingers (log10 CFU, 2.4 and 2.5, P = NS). Counts were too high on bare palms to quantitate. On gloved hands, soap was more effective than chlorhexidine on fingers (log10 CFU 1.3 and 1.7, P < .01) and palms (log10 CFU 1.5 and 2.0, P < .01), but not finger/thumbtips (log10 CFU 1.6 with each, P = NS). Residual C difficile counts were lower on gloved hands than bare hands (P < 0.01 to < 0.0001). CONCLUSIONS: The two agents did not differ significantly in residual counts of C difficile on bare hands, but on gloved hands residual counts were lower following soap wash than following chlorhexidine wash. These observations support the use of either soap or chlorhexidine as a handwash for removal of C difficile, but efficacy in the prevention of C difficile transmission must be determined by prospective clinical trials.

Aerosols↗
PubMed1991

gyrA mutations in ciprofloxacin-resistant, methicillin-resistant Staphylococcus aureus from Indiana, Minnesota, and Tennessee.

Mutational changes occurring at amino acid codons 84 and 85 located in the gyrA gene of methicillin-resistant Staphylococcus aureus (MRSA) were studied using radiolabeled oligonucleotide probes to examine the incidence of these ciprofloxacin resistance determinants in 30 MRSA isolates from Indiana, Minnesota, and Tennessee. Four separate oligonucleotide probes, one each corresponding to the wild-type sequence, a mutation at codon 84 (nucleotide 251), a mutation at codon 85 (nucleotide 253), and mutations at both, were used to examine the total genomic DNA from each of the 30 isolates, which had been restricted, electrophoresed, and Southern blotted. The probes indicated that 15 of the 28 ciprofloxacin-resistant isolates gave results consistent with a single mutation at codon 84. Four of the 28 ciprofloxacin-resistant strains had results consistent with a mutation at codon 84 and possibly at codon 85. The two ciprofloxacin-sensitive isolates from Tennessee showed homology with the wild-type probe sequence. Five isolates (4, Minnesota; 1, Tennessee) had no homology with any probe. By oligonucleotide probes, ciprofloxacin-resistant MRSA from diverse geographic regions contained similar gyrA mutations at codons 84 or 85 in 19 of 28 ciprofloxacin-resistant isolates.

Base Sequence↗
PubMed1990

Monte Carlo simulation of HIV infection in an intravenous drug user community.

Intravenous drug users are crucial to the understanding and control of human immunodeficiency virus (HIV) transmission. We have developed a population-based simulation of a community of intravenous drug users. This model was implemented using Monte Carlo techniques, which permit great flexibility in creating realistic social structures, to describe the needle-sharing network of drug users. We present the baseline behavior of this model in a generic community and demonstrate the model's utility for assessing public health interventions. Our early results demonstrate the powerful effects of social networks on HIV transmission and the importance of prevalence levels in assessing the effectiveness of interventions in the drug-injecting community.

Equipment Contamination↗
PubMed1985

X-ray pelvimetry in a breech protocol: a comparison of digital radiography and conventional methods.

X-ray evaluation of the pelvis plays a pivotal role in selecting term breech presentation for a possible trial of labor. Even minimal degrees of disproportion may have disastrous consequences for the aftercoming head. Our evaluation of x-ray pelvimetry by computerized tomography scanning suggests it is probably more accurate than conventional methods, with a concomitant decrease in fetal x-ray exposure.

Breech Presentation↗