'Per ardua...'Training tomorrow's surgeons using inter alia lessons from aviation.
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Clinical Competence↗
Biomedical subjects
C R Jackson
Publications and source records attributed to C R Jackson.
Genetic relatedness of a rarely isolated Salmonella: Salmonella enterica serotype Niakhar from NARMS animal isolates.
BACKGROUND: In the United States, Salmonella enterica serotype Niakhar is infrequently isolated. Between 1997 and 2000, the animal arm of the National Antimicrobial Resistance Monitoring System-Enteric Bacteria (NARMS) assayed a total of 22,383 Salmonella isolates from various animal sources (swine, cattle, chickens, turkeys, cats, horses, exotics and dogs) for antimicrobial susceptibility. Isolates originated from diagnostic and non-diagnostic submissions. OBJECTIVES: To study the phenotypic and genotypic characteristics of Salmonella Niakhar. METHODS AND RESULTS: Only five (0.02%) of the 22,383 isolates were identified as Salmonella Niakhar. Antimicrobial resistance testing indicated that three isolates were pan-susceptible, one isolate was resistant to ampicillin and one isolate was resistant to ampicillin, chloramphenicol, ciprofloxacin, kanamycin, nalidixic acid, streptomycin, sulfamethoxazole, tetracycline and trimethoprim/sulfamethoxazole. RAPD-PCR analysis, PFGE and ribotyping indicated that two pan-susceptible isolates were genetically similar, whereas the three remaining isolates were genetically different. The one Salmonella Niakhar isolate that was multiresistant harboured a class I integron, intI1 and two large plasmids. CONCLUSIONS: This study represents the first report of a ciprofloxacin-resistant Salmonella isolate from the animal arm of NARMS.
Animals↗
Do dispersing non-reproductive female Damaraland mole-rats, Cryptomys damarensis (Rodentia: Bathyergidae) exhibit spontaneous or induced ovulation?
The Damaraland mole-rat is a eusocial, subterranean rodent that exhibits a seasonal breeding. Non-reproductive females show physiological suppression of reproduction whilst in the confines of the natal colony. This study set out to investigate whether dispersing female Damaraland mole-rats exhibit induced or spontaneous ovulation. Fifteen non-reproductive females were removed from their natal colonies and housed individually for a period of 6 weeks. During this period urine was collected from all animals every second day. After this initial period the animals were divided into 3 groups. Females were subjected to 1 of 3 trials: a control group housed separately without a male, allowed non-physical contact, or placed in direct physical contact with vasectomized males. Urine was collected for a further 5 weeks, and urinary progesterone profiles established. All three groups showed a significant difference in urinary progesterone concentrations between the two treatment periods indicating initiation of follicular development in all animals following removal from the colony. Histological results further revealed that at least one animal in the control group and five of the six animals in the vasectomized group had corpora lutea present in the ovaries showing that ovulation has taken place. All groups had similar numbers of Graafian follicles, indicating that all females were likely to ovulate in the near future. This finding suggests that females are capable of spontaneous ovulation, but the act of coitus may advance the onset of ovulation in this arid dwelling mole-rat.
Adaptation, Physiological↗
Seasonal energetics of the Hottentot golden mole at 1500 m altitude.
Winter is an energetically stressful period for small mammals as increasing demands for thermoregulation are often coupled with shortages of food supply. In sub-tropical savannah, Hottentot golden moles (Ambysomus hottentottus longiceps) forage throughout the year and for long periods of each day. This may enable them to acquire sufficient resources from an insectivorous prey base that is both widely dispersed and energetically costly to obtain. However, they also inhabit much cooler regions; how their energy budgets are managed in these areas is unknown. We measured the daily energy expenditure (DEE), resting metabolic rate (RMR) and water turnover (WTO) of free-living golden moles during both winter and summer at high altitude (1500 m). We used measurements of deuterium dilution to estimate body fat during these two periods. DEE, WTO and body mass did not differ significantly between seasons. However, RMR values were higher during the winter than the summer and, in the latter case were also lower than allometric predictions. Body fat was also higher during the winter. Calculations show that during the winter they may restrict activity to shorter, more intense periods. This, together with an increase in thermal insulation, might enable them to survive the cold.
Algorithms↗
Enumeration and characterization of culturable arsenate resistant bacteria in a large estuary.
Arsenic is a toxic element that exists in two major inorganic forms, arsenate and arsenite. A number of bacteria have been shown to resist arsenic exposure, and even more bacteria appear to possess the genes for arsenic resistance. In this study, the numbers of culturable arsenate-resistant bacteria present in water at three coastal sites in the Lake Pontchartrain estuary, Louisiana, was determined. Despite insignificant (less than 1.33 microM) levels of arsenic in this system, 20-50% of the viable count of bacteria showed appreciable arsenate resistance, suggesting that arsenic-resistant bacteria are common and widespread. A diverse array of arsenate-resistant isolates was obtained, with 16S rRNA sequence analysis indicating 37 different bacterial strains, representing six major bacterial groups. Many of these isolates were affiliated with groups of bacteria that have been poorly characterized in terms of arsenic resistance, such as the Betaproteobacteria or Flavobacteria. Some isolates were capable of tolerating very high (> 100 mM) levels of arsenate, although arsenite resistance was generally much lower. The results suggest that arsenic-resistant bacteria are common, even in environments with insignificant arsenic contamination, and that many different groups of aquatic bacteria show appreciable arsenic resistance.
Arsenates↗
High-level aminoglycoside resistant enterococci isolated from swine.
Approximately 42% (187/444) of swine enterococci collected between the years 1999 and 2000 exhibited high-level resistance to gentamicin (MIC > or =500 microg/ml), kanamycin (MIC > or =500 microg/ml), or streptomycin (MIC > or =1000 microg/ml). Eight aminoglycoside resistance genes were detected using PCR, most frequently ant(6)-Ia and aac(6')-Ii from Enterococcus faecium. Twenty-four per cent (45/187) of total high-level aminoglycoside-resistant isolates and 26% (4/15) of isolates resistant to high levels of all three antimicrobials were negative for all genes tested. These data suggest that enterococci isolated from swine contain diverse and possibly unidentified aminoglycoside resistance genes.
Aminoglycosides↗
Effect of media, temperature and culture conditions on the species population and antibiotic resistance of enterococci from broiler chickens.
AIMS: The effect of media type, incubation temperature and enrichment period on the species population and antibiotic susceptibility of enterococci from poultry carcass rinsates was determined. METHODS AND RESULTS: Aliquots of rinsates, incubated in BBL Enterococcosel broth at 37 degrees C, 42 degrees C, or 45 degrees C for 24 and 48 h, were inoculated onto BBL Enterococcosel and M-enterococcus agar. Presumptive positive colonies were identified to species and tested for antibiotic resistance. Significant differences (P < or = 0.05) were observed for media and temperature. More Enterococcus faecalis were isolated from M-enterococcus media and at 37 degrees C while more E. faecium were isolated from Enterococcosel agar and at 45 degrees C. The number of antibiotic-resistant E. faecalis and E. faecium were also affected by media and temperature. CONCLUSIONS: Culture conditions for enterococci affect the observed species and antibiotic resistance patterns and therefore should be carefully considered. SIGNIFICANCE AND IMPACT OF THE STUDY: This study indicates that media and temperature can influence the recovery and selection of enterococcal species and antibiotic susceptibility.
Animals↗
Childhood constipation is not associated with characteristic fingerprint patterns.
BACKGROUND: It has been suggested that there is an association between simple arch fingerprint patterns and severe childhood constipation. If real, this association might be useful to predict which children have a poor prognosis. AIM: To see how many severely constipated children have simple arches, compared to non-constipated controls and their first degree relatives. METHODS: Fingerprints were classified by two blinded assessors in 30 children requiring surgery for refractory constipation, and 30 children with appendicitis, and the first degree relatives of both groups. Colonic transit times and clinical outcomes were also evaluated among constipated children. RESULTS: At least one simple arch was found in similar numbers of constipated children (13%) and their families (16%), and control children (7%) and their families (13%). Arch positivity was commoner among relatives of arch positive (6/6) than arch negative children (14/54), regardless of bowel history. Arch positivity did not identify children with prolonged transit times, nor those who required colectomy. CONCLUSIONS: Fingerprint patterns are not associated with severe childhood constipation, do not aid their management, and do not support a genetic aetiology for this problem.
Child↗
A new hollow anal dilator.
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Anus Diseases↗
Heterotopic gastric mucosa in the upper esophagus after repair of atresia.
One year after neonatal repair of esophageal atresia, a boy had intermittent mild dysphagia. Rigid esophagoscopy showed what was thought to be some inflammation at the level of the anastomosis but, at 5 years of age, with flexible esophagoscopy, this was identified as a ring of heterotopic gastric mucosa. This ring of mucosa has remained stable with surveillance up to 9 years of age. Although islands of heterotopic gastric mucosa in the esophagus are well recognized, there are no published reports of this at the level of an anastomosis for esophageal atresia with its associated clinical implications.
Anastomosis, Surgical↗
Rapid oxidation of arsenite in a hot spring ecosystem, Yellowstone National Park.
Geothermal springs within Yellowstone National Park (YNP) often contain arsenic (As) at concentrations of 10-40 microM, levels that are considered toxic to many organisms. Arsenite (As(III)) is often the predominant valence state at the point of discharge but is rapidly oxidized to arsenate (As(V)) during transport in shallow surface water. The current study was designed to establish rates and possible mechanisms of As(III) oxidation and to characterize the geochemical environment associated with predominant microbial mats in a representative acid-sulfate-chloride (pH 3.1) thermal (58-62 degrees C) spring in Norris Basin, YNP. At the spring origin, total soluble As was predominantly As(III) at concentrations of 33 microM. No oxidation of As(III) was detected over the first 2.7 m downstream from the spring source, corresponding to an area dominated by a yellow filamentous S0-rich microbial mat However, rapid oxidation of As(III) to As(V) was observed between 2.7 and 5.6 m, corresponding to termination of the S0-rich mats, decreases in dissolved sulfide, and commencement of a brown Fe/As-rich mat. Rates of As(II) oxidation were estimated, yielding an apparent first-order rate constant of 1.2 min(-1) (half-life = 0.58 min). The oxidation of As(III) was shown to require live organisms present just prior to and within the Fe/As-rich mat. Complementary analytical tools used to characterize the brown mat revealed an As:Fe molar ratio of 0.7 and suggested that this filamentous microbial mat contains iron(III) oxyhydroxide coprecipitated with As(V). Results from the current work are the first to provide a comprehensive characterization of microbially mediated As(III) oxidation and the geochemical environments associated with microbial mats in acid-sulfate-chloride springs of YNP.
Arsenites↗
Molecular analysis of microbial community structure in an arsenite-oxidizing acidic thermal spring.
Electron microscopy (EM), denaturing gradient gel electrophoresis (DGGE) and 16S rDNA sequencing were used to examine the structure and diversity of microbial mats present in an acid-sulphate-chloride (pH 3.1) thermal (58-62 degrees C) spring in Norris Basin, Yellowstone National Park, WY, USA, exhibiting rapid rates of arsenite oxidation. Initial visual assessments, scanning EM and geochemical measurements revealed the presence of three distinct mat types. Analysis of 16S rDNA fragments with DGGE confirmed the presence of different bacterial and archaeal communities within these zones. Changes in the microbial community appeared to coincide with arsenite oxidation activity. Phylogenetic analysis of 1400 bp 16S rDNA sequences revealed that clone libraries prepared from both arsenic redox active and inactive bacterial communities were dominated by sequences phylogenetically related to Hydrogenobacter acidophilus and Desulphurella sp. The appearance of archaeal 16S rDNA sequences coincided with the start of arsenite oxidation, and sequences were obtained showing affiliation with both Crenarchaeota and Euryarchaeota. The majority of archaeal sequences were most similar to sequences obtained from marine hydrothermal vents and other acidic hot springs, although the level of similarity was typically just 90%. Arsenite oxidation in this system may result from the activities of these unknown archaeal taxa and/or the previously unreported arsenic redox activity of H. acidophilus- or Desulphurella-like organisms. If the latter, arsenite oxidation must be inhibited in the initial high-sulphide zone of the spring, where no change in the distribution of arsenite versus arsenate was observed.
Archaea↗
The effectiveness of prophylactic etodolac on postendodontic pain.
To determine if prophylactic etodolac would significantly reduce postendodontic pain, when compared with ibuprofen or placebo, 36 patients consented to single blind oral administration of either 400 mg of etodolac, 600 mg of ibuprofen, or a placebo, before conventional one-appointment root canal therapy. Patient-reported visual analog scale ratings of pain intensity were conducted upon initial clinical presentation, immediately postoperative, 4, 8, 12, 24, 48, and 72 h after initiation of root canal therapy. Results showed that prophylactic ibuprofen administration significantly reduced postendodontic pain at 4 and 8 h after initiation of root canal therapy, when compared with etodolac and a placebo. Patients with a periapical diagnosis of acute apical periodontitis or with a Phoenix abscess showed a significant increased need for additional medication after completion of root canal therapy, compared with all other periapical diagnoses.
Acute Disease↗
Long-term trends in childhood infectious disease mortality rates.
OBJECTIVES: This study assessed long-term trends in US childhood infectious disease mortality rates (CIDMR). METHODS: We calculated age-adjusted and age group-specific US CIDMR (1968-1996) by using data from the Compressed Mortality File (1968-1992, 1996) and Multiple Cause of Death Files (1993-1995) of the National Center for Health Statistics and English data for historical comparison (1861-1964). RESULTS: US CIDMR declined continuously from 1968 to 1996, although the rate of decline slowed after 1974. Respiratory and central nervous system categories declined most; HIV-related deaths offset these declines somewhat. CONCLUSIONS: CIDMR declined nearly 200-fold between 1861 and 1996, but no substantive improvement occurred after 1986.
Adolescent↗
Evaluation of surrogate markers and clinical outcomes in two-year follow-up of eighty-six human immunodeficiency virus-infected pediatric patients.
OBJECTIVES: To evaluate the prognostic value of surrogate markers (HIV RNA copy number, CD4 counts and CDC clinical and immunologic categories) in HIV-infected children through a 2-year period. METHODS: Eighty-six HIV-infected children followed by the Duke Pediatric HIV Clinic in the fall of 1994 were evaluated for plasma HIV RNA concentration (viral load), CD4 lymphocyte percentage, age, antiretroviral treatment status and CDC clinical and immunologic categories. Follow-up evaluations were performed for approximately 2 years, and the time to progression to a new CDC category C diagnosis or death was noted. RESULTS: Of 86 children 22 had progression to new Category C diagnosis or death. Seven children died, 17 had a new Category C diagnosis and 2 had both. Among children who progressed, the median CD4 percentage at entry was 3% (absolute count, 75 cells/mm3), whereas children who had no disease progression entered with a median of 29% (868 cells/mm3). The overall median viral load at study entry was 4.58 log10 copies/ml (38,019 copies/ml, with a range of 1.7 to 6.78 logs). Children who had no disease progression had a median log copy number of 4.43, whereas 5.18 was the median for children whose disease progressed. Log copy number declined over time in children < 3 years of age, whereas it remained fairly consistent for children 3 years or older. Progression rates were determined by entry plasma HIV RNA concentration quartiles [quartile boundaries < 4.18, 4.58, > 5.08 log RNA copy/ml (< 15,136, 38,019 and > 120,226 copies/ml, respectively)]. Progression rates by quartile were 0 of 21, 4 of 22, 5 of 21 and 13 of 22. Kaplan-Meier survival curves defined by CD4% less than or greater than 15 and log RNA less than or greater than 5.0 (100,000) revealed that patients with CD4% less than 15 and plasma HIV RNA concentration > 5 log10 copies/ml did least well: 11 of 12 (92%) had a progression event at a median of 179 days. Patients with a high CD4 percentage and high viral load, or a low CD4 percentage and low viral load did similarly; 5 of 14 (36%) and 4 of 12 (33%) had progression events, respectively. Patients with high CD4 percentage and low viral load did best: only 2 of 48 (4%) had a progression event. CONCLUSIONS: The two most significant prognostic indicators of disease progression were the initial CD4 percentage and the plasma HIV RNA concentration, and a combination of CD4 percentage and virus load best predicted which children had progression events. Progression was less common in children who had < 100,000 HIV RNA copies/ml initially (6 of 60 vs. 16 of 26; P < 0.001; relative risk 0.16). Therefore it seems reasonable that in a child for whom complete suppression is not possible, a threshold of 100,000 (5 log10 copies/ml) can be used to mandate a change in therapy.
Adolescent↗
Changes in bacterial species composition in enrichment cultures with various dilutions of inoculum as monitored by denaturing gradient gel electrophoresis.
Denaturing gradient gel electrophoresis revealed changes in the bacterial species obtained from enrichment cultures with different inoculum dilutions. This inoculum dilution enrichment approach may facilitate the detection and isolation of a greater number of bacterial species than traditional enrichment techniques.
Bacteria↗
The exposure of children to lead, by J. Julian Chisholm and Harold E. Harrison, Pediatrics, 1956:18;943-958.
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Child↗
Effect of influenza immunization on immunologic and virologic characteristics of pediatric patients infected with human immunodeficiency virus.
OBJECTIVES: We evaluated the responses of HIV-infected children to a single dose of split-virus influenza vaccine and the relationship to viral load and other characteristics. METHODS: Fifty-three HIV-infected children ages 1.8 to 13.2 years were given influenza vaccine for the 1994 to 1995 influenza season (Wyeth-Ayerst: A/Texas H1N1, A/Shangdong H3N2 and B/Panama). Immunologic and virologic factors were assessed at the time of and 2 to 10 weeks after immunization. RESULTS: The differences between pre- and postimmunization CD4+ counts, CD4+:CD8+ ratios and viral load were not significant. Thirty-one of 53 children (58.4%) had a > 2-fold increase and 16 of 53 (30%) had a 4-fold rise in their postimmunization antibody titers for at least one component of the vaccine. Influenza immunization in the 1993 to 1994 flu season and administration of intravenous immunoglobulin around the time of immunization was not associated with immune response to the vaccine. Factors that were negatively associated with antibody response included increased time between samples (P = 0.004) and decreased preimmunization CD4+:CD8+ ratio (P = 0.02). CONCLUSIONS: Influenza immunization in this population is safe, and a positive antibody response to influenza immunization is not associated with significant clinical events or change in HIV-1 plasma viral burden.
Adolescent↗