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Biomedical subjects

R Ellis

Publications and source records attributed to R Ellis.

At least 181 records · Page 10Linked to original sources
PubMedDate not supplied

Determination of tetracycline residues in animal tissues by liquid chromatography.

A simple liquid chromatographic (LC) method was developed for the determination of tetracyclines (oxy-tetracycline, tetracycline and chlortetracycline) in animal tissues. Isolation of tetracyclines from biological matrices was performed with oxalic buffer followed by dechelation and deproteinization with oxalic acid-acetonitrile solution. For clean-up solid phase extraction with a SDBI (styrene-divinylbenzene) cartridge was used. LC analysis was performed on a polymeric analytical column (PLRP-S 5 microns, 150 x 4.6 mm) and using an oxalic acid mobile phase (0.01 M oxalic acid - acetonitrile 75:25, v/v). The whole procedure was validated for intra- and inter-assay reproducibility determination by assaying muscle, liver and kidney samples supplemented with tetracyclines at the level of 50, 100 and 200 ng/g, respectively. The statistical evaluation demonstrates high absolute recovery (> 80%) and low coefficient of variation (< 10%) for all analysed samples. The detection limits for tetracyclines were 10-15 ng/g in muscle, and 20-25 ng/g in liver and kidney samples, depending on the analyte.

Animals↗
PubMedDate not supplied

Usefulness of the dietary phytic acid/zinc molar ratio as an index of zinc bioavailability to rats and humans.

Evidence suggests that rats can tolerate a dietary phytate/Zn molar ratio greater than 15 if the dietary Zn concentration is high. High dietary Ca exacerbates the effect of phytic acid on Zn utilization by rats. In a short term (15 d) balance trial with adult men, we observed slightly greater Zn balance when whole compared to dephytinized wheat bran was consumed (molar ratios 12 and 1.2, respectively). There was, however, greater fecal excretion of Zn during the first 5 d whole bran was consumed. In a second study, Na phytate was the major source of phytic acid and Zn balance was less when the phytate/Zn molar ratio was greater than 16 compared to 4. The difference was not significant, however, and there was evidence of physiological adjustments to maintain homeostasis when the high ratio diet was consumed. Mean Zn intake averaged 17 mg (0.26 mmole) and 11 mg (0.17 mmole) daily for the bran and Na phytate studies, respectively. The level of Zn intake may influence the response of humans to varying phytate/Zn ratios. Comparison of isotope retention studies and the balance data is discussed. Some information on the relationship of dietary Ca to the phytate/Zn effect in human diets is gathered from current literature. The phytate/Zn molar ratio is a useful index of Zn bioavailability.

Absorption↗
PubMedDate not supplied

Immunogenicity and safety of Haemophilus influenzae type b polysaccharide-Neisseria meningitidis conjugate vaccine in 7.5 micrograms liquid formulation: a comparison of three lots with the 15.0 micrograms lyophilized formulation. Study Group for 7.5 micrograms Liquid PedvaxHIB.

We conducted a multicenter, single-blind, randomized comparisons of the immunogenicity and safety of three manufacturing-scale lots of 7.5 micrograms liquid Haemophilus influenzae type b polysaccharide- Neisseria meningitidis conjugate vaccine (PRP-OMPC) and a single lot of 15.0 micrograms lyophilized PRP OMPC. A total of 908 infants were entered into the study. Each infant received two primary injections intramuscularly 2 months apart beginning at age 2-6 months and a booster injection at 12-15 months. Blood samples for serology were obtained before each injection and 1 month after the second and the booster dose. Immune responses were measured by radioimmunoassay. Approximately 80% of the infants achieved a titer > 1.0 micrograms ml-1 after the second primary dose of all four lots tested: the geometric mean titer (GMT) was ca 3 micrograms ml-1 for each vaccine group. After the booster dose, more than 90% of infants from each vaccine group had a titer > 1.0 microgram ml-1;GMTs ranged from 8 to 10 micrograms ml-1. No serious vaccine-associated adverse reactions were reported. Thus the 7.5 liquid PRP OMPC vaccine was at least as immunogenic and well tolerated as the 15.0 micrograms lyophilized vaccine.

Bacterial Outer Membrane Proteins↗
PubMedDate not supplied

Allergen-induced changes in bone marrow progenitors and airway responsiveness in dogs.

An increased production of inflammatory cell progenitors (colony-forming cells, CFUs) may contribute to airway inflammation, since CFUs increase after allergen inhalation in asthmatics. We examined the effect of allergen inhalation, with or without budesonide pretreatment, on bone marrow CFU production in dogs with allergen-induced airway hyperresponsiveness. Allergen inhalation increased airway responsiveness (p < 0.001) as well as the number of CFUs induced in vitro by recombinant canine stem cell factor (p < 0.001) and granulocyte-colony-stimulating factor (p = 0.035). Budesonide reduced the allergen-induced increases in airway responsiveness (p = 0.005) and abolished the allergen-induced increases in the numbers of CFUs (p < 0.005). These findings provide the first direct evidence that allergen inhalation increases bone marrow granulocyte progenitor production and suggest that such increases may contribute to the development of airway hyperresponsiveness in asthma. The effectiveness of inhaled corticosteroids in asthma may result, in part, from effect on bone marrow production of inflammatory cells.

Administration, Inhalation↗
PubMedDate not supplied

Bone marrow progenitors in allergic airways diseases: studies in canine and human models.

In a canine model of Ascaris suum-inducible bronchial hyperresponsiveness, we previously demonstrated that bone marrow-derived myeloid progenitors rise within 24 h of allergen inhalation; this effect is abolished by pretreatment with inhaled budesonide. We now report that this allergen-induced bone marrow response is observable in human asthmatics, and involves increases in both neutrophil-macrophage and eosinophil-basophil progenitors, within 6 h of allergen inhalation, as measured either by hematopoietic colony assays or by flow cytometric analyses of CD34+, IL-3R alpha+, and/or IL-5-responsive cell populations. In dogs, but not in humans, a transferrable serum hematopoietic activity accounts for the marrow response to inhaled allergen. These findings suggest that allergen-induced increases in bone marrow progenitor formation depend either on a serum hematopoietic factor(s) released after allergen challenge, or upon constitutive marrow upregulation of specific progenitors in allergic airway disease. Further studies to characterize the serum hematopoietic factor(s) and to determine the nature of any atopy-related progenitor profile are in progress.

Animals↗
PubMedDate not supplied

The use of a hand-held computer to record clinical trial data in general practice: a pilot study.

A system has been developed to collect and process clinical trial data in general practice using a hand-held computer in the patient's presence. It was based on a Psion Organiser II (model XP) computer using software produced for the trial. The major advantages are: (a) avoidance of protocol violations and other incorrect data entries; and (b) saving of time for investigators and company personnel. The present coding of symptoms was found to be the only major drawback, but this problem could be remedied for future studies.

Acetaminophen↗
PubMedDate not supplied

A novel EMG/video system for the analysis of movement.

A simple movement-analysis system is described which provides a video display of the moving image and an easily-observable EMG signal in the form of a time-synchronized light-emitting-diode (LED) display. Its salient feature is the economic and meaningful way in which both data are displayed simultaneously. Its applications in the field of clinical education and training, in diagnosis, and in rehabilitation are discussed.

Data Display↗
PubMedDate not supplied

Primary tooth enamel surface topography with in vitro argon laser irradiation alone and combined fluoride and argon laser treatment: scanning electon microscopic study.

PURPOSE: The purpose of this descriptive scanning electron microscopic study was to characterize surface alterations in primary tooth enamel after in vitro argon laser irradiation alone and combined with topical fluoride treatment either before or after argon laser irradiation. METHODS: Twenty extracted or exfoliated primary teeth underwent soft tissue debridement and a fluoride-free prophylaxis. Buccal and lingual surfaces were determined to be caries-free by macroscopic examination (stereo-zoom binocular microscope, x16). Treatment groups were: (1) no-treatment control; (2) argon laser irradiation (ALI; 11.5 J/cm2); (3) 1.23% acidulated phosphate fluoride (APF before ALI); and (4) ALI before APF. Both buccal and lingual surfaces were evaluated following standard scanning electron microscopic preparation techniques. RESULTS: With controls, enamel surfaces were relatively smooth with occasional enamel prism ends present on their surfaces. There were no areas with cavitations or surface defects. With ALI, the lased surfaces were roughened mildly to moderately irregular without cavitation of the enamel or exposure of enamel prism ends. The surfaces possessed adherent granules to globules, with most being <3 microm in greatest dimension. Only occasional fine cracks and porosities in the surface coatings were noted and these were typically less than 1 microm in width or diameter. With APF before ALI, the surfaces possessed an irregular contour, with numerous granules to globules varying in size from 1 to 3 microm in greatest dimension. With ALI before APF, a homogenous confluent surface was present that masked typical enamel surface markings. The previously noted adherent granules and globules with argon laser treatment alone or APF before ALI were not seen. The argon laser effects on the enamel surfaces were masked by the uniformity of these surface coatings. CONCLUSIONS: Argon laser irradiation and combined APF and argon laser treatment of primary tooth enamel created surfaces that may provide a protective barrier against a cariogenic attack. The surface coatings associated with combined APF and argon laser treatment may contain fluoride-rich calcium and phosphate mineral phases that could act as reservoirs for fluoride, calcium, and phosphate and provide a certain degree of protection from a caries lesion challenge.

Acidulated Phosphate Fluoride↗