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Biomedical subjects

C A Carson

Publications and source records attributed to C A Carson.

At least 19 recordsLinked to original sources
PubMed2000

Cloned lines of Babesia bovis differ in their ability to induce cerebral babesiosis in cattle.

Clones of a Babesia bovis isolate known to cause particularly severe cerebral babesiosis were tested for virulence phenotype by inoculation of cattle. Clones were selected for phenotyping by two criteria - rate of growth in culture and hybridization of a virulence-related probe to Southern blots. Largely on the basis of associated mortality, B. bovis clones were judged to vary in their pathogenic potential.

Animals↗
PubMed2000

Theileriosis in a Missouri beef herd caused by Theileria buffeli: case report, herd investigation, ultrastructure, phylogenetic analysis, and experimental transmission.

A 6-year-old Simmental cow infected with Theileria buffeli had a clinical disease characterized by theilerial parasitemia, macrocytic normochromic anemia with acanthocytosis and spherocytosis, lymphoid hyperplasia (lymphocytosis, edematous lymphadenomegaly), dysproteinemia, evidence of liver disease, and a low serum antibody titer against T. buffeli. The cow was in a herd in which all cattle originated in Missouri; 22/75 (29%) of cattle had a theilerial parasitemia and 26/75 (35%) had titers to T. buffeli of > or =1:160. Classification of the Missouri bovine organism as T. buffeli was based on DNA sequencing and comparison to sequences for T. buffeli and Theileria sp. type A obtained from GenBank. Intraerythrocytic veils and piroplasms were seen during transmission electron microscopy. The organism was successfully transmitted to two splenectomized calves, which developed mild anemias while parasitemic. Blood from the second calf was used as the source of T. buffeli antigen for an indirect immunofluorescence antibody test. Theilerial isolates from a Missouri white-tailed deer were also sequenced and resembled Theileria sp. types F and G and were not consistent with the bovine organism.

Animals↗
PubMed1999

Immunogenicity of recombinant Babesia microti hsp70 homologue in mice.

A Babesia microti hsp70 homologue was cloned, expressed in a prokaryotic system and tested in a pilot study for protection against lethal challenge. Results showed that 30% of the mice inoculated with recombinant protein (rBm hsp70) survived challenge, while all of the controls died. Evidence of antibody response to the hsp homologue was detected by Western blot analysis, but no protection was imparted through passive transfer of convalescent serum. Passively transferred spleen cells, from mice which survived challenge, also failed to impart protection. The mechanism of partial immunity suggested by these observations remains to be elucidated.

Animals↗
PubMed1997

Evaluation of DNA "fingerprinting" for predicting the potential of E. coli O157:H7 isolates to cause hemolytic uremic syndrome (HUS).

Escherichia coli O157:H7 has been recognized since 1982 as a serious human pathogen spread by contaminated food and water. Pulsed-field gel electrophoresis has proven useful for identification of specific isolates/strains of this organism. Hemolytic uremic syndrome (HUS), generally occurring in children or the aged, is the most severe sequela associated with E. coli O157:H7 infection. The presently described work was designed to compare the genomic profile of isolates known to have caused HUS with those having had no such involvement. We asked the question: "Can we develop the means to recognize an 'HUS-prone' E. coli isolate and thereby alert medical personnel to the increased risk?" Twenty-two HUS-related and 10 HUS-unrelated E. coli O157:H7 samples were chosen for genomic analysis. Isolates were cultured overnight prior to being embedded in agarose gel plugs. Plugs were digested, using Xbal restriction endonuclease, and subjected to pulsed-field gel electrophoresis (PFGE) for 20 hours. Gels were stained with ethidium bromide, photographed under ultraviolet light, and Southern blotted. Radiolabeled toxin gene probes were used for hybridization assays. The two classes of isolates were compared by optical imaging software. A computer-generated dendrogram, based on restriction profiles, offered strong initial evidence that the HUS sequela may be produced by a particularly virulent and identifiable clone. The predictive value of this finding appears to be substantial.

DNA Fingerprinting↗
PubMed1997

Unique Salmonella choleraesuis surface protein affecting invasiveness. Possible inv related sequence.

TnphoA mutagenesis of a Salmonella choleraesuis isolate recovered from septicemic infection of feeder pigs resulted in 56 PhoA+ KnR StrR mutants. Thirty-five mutants exhibited reduced levels of invasion in the Hep-2 cell model and were examined by SDS-PAGE Western Blot analysis using an anti-alkaline phosphatase antibody to visualize the insertion gene products. A mutant which produced a gene fusion product of 95 kDa and exhibited > 90% reduction in invasion was subcloned. A 10 Kb BamHI fragment of the chromosome containing the phoA insert was detected by hybridization and cloned into a pGEM vector. The resulting 1657 base sequence contained a 1104 bp ORF with two short regions of homology with S. typhimurium invF and invG. one region of homology with lcrD of Yersinia pseudotuberculosis but contained largely unique sequences not contained in Gene Bank. The full length sequence was not obtained as there was no stop codon detected. The % G+C was 44%, considerably lower than that of the Salmonella chromosome, but compatible with the proposed Yersinia origin of the inv genes. The NH2 387 a.a. sequence includes 5 transmembrane regions, resembling the model derived from the hydrophobicity plot of S. typhimurium InvA.

Antigens, Surface↗
PubMed1996

Prognosis and outcomes of patients with community-acquired pneumonia. A meta-analysis.

OBJECTIVE: To systematically review the medical literature on the prognosis and outcomes of patients with community-acquired pneumonia (CAP). DATA SOURCES: A MEDLINE literature search of English-language articles involving human subjects and manual reviews of article bibliographies were used to identify studies of prognosis in CAP. STUDY SELECTION: Review of 4573 citations revealed 122 articles (127 unique study cohorts) that reported medical outcomes in adults with CAP. DATA EXTRACTION: Qualitative assessments of studies' patient populations, designs, and patient outcomes were performed. Summary univariate odds ratios (ORs) and rate differences (RDs) and their associated 95% confidence intervals (CIs) were computed to estimate a summary effect size for the association of prognostic factors and mortality. DATA SYNTHESIS: The overall mortality for the 33,148 patients in all 127 study cohorts was 13.7%, ranging from 5.1% for the 2097 hospitalized and ambulatory patients (in six study cohorts) to 36.5% for the 788 intensive care unit patients (in 13 cohorts). Mortality varied by pneumonia etiology, ranging from less than 2% to greater than 30%. Eleven prognostic factors were significantly associated with mortality using both summary ORs and RDs: male sex (OR = 1.3; 95% CI, 1.2 to 1.4), pleuritic chest pain (OR = 0.5; 95% CI, 0.3 to 0.8), hypothermia (OR = 5.0; 95% CI, 2.4 to 10.4), systolic hypotension (OR = 4.8; 95% CI, 2.8 to 8.3), tachypnea (OR = 2.9; 95% CI, 1.7 to 4.9), diabetes mellitus (OR = 1.3; 95% CI, 1.1 to 1.5), neoplastic disease (OR = 2.8; 95% CI, 2.4 to 3.1), neurologic disease (OR = 4.6; 95% CI, 2.3 to 8.9), bacteremia (OR = 2.8; 95% CI, 2.3 to 3.6), leukopenia (OR = 2.5, 95% CI, 1.6 to 3.7), and multilobar radiographic pulmonary infiltrate (OR = 3.1; 95% CI, 1.9 to 5.1). Assessments of other clinically relevant medical outcomes such as morbid complications (41 cohorts), symptoms resolution (seven cohorts), return to work or usual activities (five cohorts), or functional status (one cohort) were infrequently performed. CONCLUSIONS: Mortality for patients hospitalized with CAP was high and was associated with characteristics of the study cohort, pneumonia etiology, and a variety of prognostic factors. Generalization of these findings to all patients with CAP should be made with caution because of insufficient published information on medical outcomes other than mortality in ambulatory patients.

Adult↗
PubMed1996

Videofluoroscopic assessment in children with severe cerebral palsy presenting with dysphagia.

In this study 16 patients with severe spastic cerebral palsy with an age range between 6 months and 16 years were examined using videofluoroscopy and a modified barium meal. All patients were slow, inefficient eaters. Silent aspiration was demonstrated in five cases. The latter five patients demonstrated a delayed swallow reflex but there was little correlation between aspiration and the oral phase of deglutition. Our data confirms the impression that early diagnostic workup including videofluoroscopy is helpful in managing the feeding difficulties in these children, and may prevent chronic aspiration and malnutrition.

Adolescent↗
PubMed1996

Pharmacokinetics of flosequinan in patients with heart failure.

OBJECTIVE: The pharmacokinetics of flosequinan were studied in a group of 18 patients with chronic cardiac failure. RESULTS: After a single dose of 100 mg, Cmax of the parent compound (2.52 mg.l-1) was recorded at 1.4 h, and of the sulphone metabolite flosequinoxan at 21.7 h. The plasma elimination half lives of the parent compound (6.4 h) and of the metabolite (54.3 h) were prolonged compared to previous studies in normal volunteers. After repeated dose administration for 36 days, the kinetics of the parent compound and metabolite remained essentially unchanged with an expected significant accumulation of metabolite (Cmax 8.4 vs 3.21 mg.l-1). No adverse effects were observed. CONCLUSION: It is possible that altered drug kinetics in patients with heart failure, probably related to altered hepatic blood flow, could contribute to drug toxicity.

Aged↗
PubMed1995

Excimer laser treatment for high and extreme myopia. The Melbourne Excimer Laser and Research Group.

OBJECTIVE: The excimer laser allows the controlled ablation of corneal tissue to correct refractive error. We assessed the efficacy of excimer laser treatment for persons with high (spherical equivalent between -5 and -10 diopters) and extreme (spherical equivalent greater than -10D) myopia. METHODS: Patients were assessed 1, 3, and 6 months postoperatively. A VisX Twenty/Twenty laser was used. Visual acuity, refraction, corneal clarity, and adverse reactions were evaluated at each visit. RESULTS: Six month follow-up data were available for 194 high myopes and 53 extreme myopes. Postoperative healing was similar for the two groups. Six months postoperatively, 89.2% of high myopes and 49% of extreme myopes were within 2D of planned refraction. At 6 months, 28% of high myopes had an uncorrected visual acuity of 20/20 and 71% had an uncorrected visual acuity of 20/40. Of extreme myopes, 4% had an uncorrected visual acuity of 20/20 and 30% had an uncorrected visual acuity of 20/40. Significantly more corneal haze was observed in the extreme myopes. Loss of 2 or more lines of best corrected visual acuity was observed in 13% of high myopes and 13% of extreme myopes at 6 months. CONCLUSIONS: Excimer laser photorefractive keratectomy is an alternative means of treating high and extreme myopia and can cause a significant reduction in myopia. There is a need to gather further information as more patients are followed up for greater time.

Adult↗
PubMed1995

One-year evaluation of excimer laser photorefractive keratectomy for myopia and myopic astigmatism. Melbourne Excimer Laser Group.

OBJECTIVE: To evaluate prospectively the efficacy and safety of excimer laser photorefractive keratectomy in the treatment of myopia and myopic astigmatism. METHODS: Up to 15 diopters (D) of myopia with or without astigmatism of less than 6 D was treated with an excimer laser (VISX Twenty/Twenty). One hundred fifty procedures have been followed up for more than 12 months. RESULTS: Postoperative refractions were generally stable after 3 months without significant early overcorrection. Of those eyes treated with spherical equivalents of 5 D or less, 96% were within 1 D of the targeted refraction after photorefractive keratectomy and 88% had uncorrected visual acuities of 20/40 or better. At 12 months, 77% of all 150 eyes treated achieved an uncorrected visual acuity of 20/40 or better and 81% were within 1 D of the intended correction. Nine eyes (6%) lost 2 or more lines of best corrected visual acuity and 14 (9%) gained 2 or more lines. Adverse reactions were reported in 12 patients (8%) during the postoperative period. CONCLUSIONS: Photorefractive keratectomy is capable of correcting low and moderate myopic errors with a relatively high degree of accuracy and safety. The predictability and stability of the postoperative refraction during the first 12 months seem to be good.

Adult↗
PubMed1995

Prevalence of central islands after excimer laser refractive surgery.

We conducted a study to determine the prevalence of central islands after refractive excimer laser surgery and the factors associated with their occurrence. A VISX Twenty/Twenty excimer laser was used to perform 157 photorefractive keratectomy (PRK) and 263 photorefractive astigmatic keratectomy (PARK) procedures. Corneal topography was assessed in 156 patients three months postoperatively using a topographic analysis system. Central islands were seen in 67% of patients; 26% had islands of 3.0 diopters (D) or more in height. Occurrence was associated with the laser suction nozzle being fixed during the procedure (P < .05). There was no demonstrable effect of central islands on visual acuity or refractive outcome, nor was there any relation to the amount of attempted correction or type of procedure (PARK or PRK). Central islands with a curvature difference of less than 3.0 D were seen more frequently than an absence of islands, suggesting these may be a "normal" postoperative topographic variation. The effect of nozzle position on island formation suggests that plume removal or corneal hydration may be important, as is corneal epithelial healing.

Adult↗
PubMed1995

A novel psychophysical procedure for bitter taste assessment in rats.

A persistent problem with attempts to examine bitter taste mechanisms has been the lack of adequate behavioral methodology providing data which parallels that obtained from physiological investigations. We developed a brief contact procedure to assess the ability of rats to detect the presence of a weak bitter compound dissolved in a strong sucrose solution. Male Fischer 344 rats were trained to drink immediately to multiple 10-s presentations of acetaminophen (2, 8, 32, 128 mM), chlorpheniramine maleate (1, 3, 9, 27 mM) L-tryptophan (13.5, 27, 54, 108 mM), pseudoephedrine hydrochloride (1, 4, 16, 64 mM) and quinine hydrochloride (0.008, 0.04, 0.2, 1.0 mM) dissolved in 0.8 M sucrose. The number of licks to sucrose and water were also measured. A microcomputer controlled stimulus presentations and measured the animal's licks of each solution during each 10-s presentation. The responses to the bitter+sucrose mixture were significantly decreased at most concentrations with increasing levels of the bitter component. This was true for all five bitter-tasting compounds, but over different concentration ranges relatively unique to each compound. The present study is the first to characterize the sensory effects of acetaminophen, pseudoephedrine, and chlorpheniramine maleate, all purported to taste bitter to humans. These results demonstrate rats' acute ability to discriminate by taste not only the presence but the concentration of a dilute bitter compound dissolved in a strong sucrose solution.

Acetaminophen↗
PubMed1995

Knowledge of glaucoma, and its relationship to self-care practices, in a population sample.

OBJECTIVE: To determine the level of knowledge of glaucoma in a population-based sample, and its relationship to self-care practices. DESIGN AND SUBJECTS: A cluster random sample of the Melbourne population 40 years of age and older was interviewed. One thousand seven hundred and eleven residents living in five randomly selected Melbourne metropolitan suburbs, each consisting of two adjacent census collector districts. MEASURES: Questions were asked concerning respondents' awareness, knowledge and description of the disease. Respondents were also asked the year of their last visit to their eye health care provider. RESULTS: Seventy per cent of the sample had heard of glaucoma. However, only 22% provided a description that demonstrated a reasonable understanding of the disease. A lack of awareness and knowledge of glaucoma appeared to be negatively related to self-care practices. CONCLUSION: Serious deficiencies in the basic knowledge of glaucoma in the community was demonstrated. This has significant public health implications as only a small percentage of the at-risk population may present themselves for assessment and treatment. Informing the community about glaucoma is an important step in promoting preventative ophthalmic care and reducing visual impairment and blindness.

Adult↗
PubMed1995

Escherichia coli O157:H7 restriction pattern recognition by artificial neural network.

An artificial neural network model for the recognition of Escherichia coli O157:H7 restriction patterns was designed. In the training phase, images of two classes of E. coli isolates (O157:H7 and non-O157:H7) were digitized and transmitted to the neural network. The system was then tested for recognition of images not included in the training set. Promising results were achieved with the designed network configuration, providing a basis for further study. This application of a new generation of computation technology serves as an example of its usefulness in microbiology.

Animals↗
PubMed1995

Fastpac visual field screening.

In epidemiology, screening for visual field defects has traditionally been expensive, time consuming and laborious. To achieve cost- and time-effective visual field screening, a faster algorithm has been developed for the Humphrey perimeter called Fastpac, which is designed to achieve threshold perimetry in two-thirds the time of the standard algorithm. We compared the Fastpac and conventional full-threshold 24-2 fields obtained in 39 eyes of 36 participants. We divided the participants' fields into normal (14) and glaucomatous (25) visual field groups, and compared the test times, number of questions asked and statistical parameters generated for each field for Fastpac as compared to the standard algorithm. Then we divided the participants' fields into Fastpac and standard fields and again compared the test times, number of questions and statistical parameters. Finally we asked trained observers to judge the fields as being normal or abnormal, in a masked fashion, and found a high degree of agreement between the fields generated by Fastpac and standard. Fastpac offers accurate full-threshold screening in two-thirds the time of the conventional algorithm and would be very useful for large scale prevalence studies in ophthalmic epidemiology.

Adult↗
PubMed1995

The epidemiology of cataract: a review of the literature.

Cataract is a major cause of blindness, accounting for nearly half of all blindness worldwide. Epidemiological research provides the principles and methods to assess the extent of cataract, and supplies the necessary information for policy planning. Obtaining accurate epidemiological data on cataract is essential to ascertain and estimate the cost of primary and secondary eye health care needs. Determining risk factors is also necessary to reduce the economic and social repercussions associated with the disease. The following paper presents a review of the epidemiology of cataract in the middle to elderly age group.

Aged↗