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Biomedical subjects

J Webb

Publications and source records attributed to J Webb.

At least 109 records · Page 6Linked to original sources

Antagonism of Pseudomonas cepacia against phytopathogenic fungi.

Two strains of Pseudomonas cepacia, RJ3 and ATCC 52796, have been identified as potential antagonists of fungal plant pathogens. We have compared the antagonistic activity of these two strains against various fungal pathogens. Although both strains displayed high levels of antagonism, ATCC 52796 was slightly more antagonistic than RJ3. The antagonist from RJ3 has been identified as the antifungal compound pyrrolnitrin after purification by HPLC and characterization by UV, IR, NMR, and mass spectroscopy. Both strains also antagonized the fungi by production of volatile compound(s), which have not yet been identified. Both strains are similar with respect to in vitro antagonism, mechanism of antagonism, and sensitivity to antibiotics.

Antibiosis↗

Chlorinated dibenzo-p-dioxins and dibenzofurans and the human immune system. 1. Blood cell receptors in volunteers with moderately increased body burdens.

Using monoclonal antibodies (mAbs) and flow cytometry, we studied a variety of surface receptors on lymphocyte subpopulations of workers with moderately increased body burdens of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and of other polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/PCDF), expressed here as International-Toxicity Equivalencies (I-TE). The hypothesis to be tested was whether or not humans exhibit a similar susceptibility to PCDDs/PCDFs with respect to the surface receptors found previously to respond to small doses of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in Callithrix jacchus. These are: helper-inducer (memory) T cells (CD4+CD45R0+CD45RA-CD29highCD11a+), CD20+ B cells, and cytotoxic T cells (CD8+CD56+/CD57+). Furthermore, 68 triple-labellings with mAbs were performed on the cells of each volunteer to possibly generate further hypotheses. It was evaluated whether any of the variables might be used as a biomarker of effects for this class of compounds. There were two main goals: (1) to evaluate whether workers with a moderately increased PCDD/PCDF-body burden [25-140 ppt TCDD or 104-522 ppt I-TE in blood fat] exhibit changes in the surface receptors of white blood cells, as observed in previous studies in non-human primates, and (2) to clarify whether persons at the upper range [10-23 ppt TCDD or 30-90 ppt I-TE in blood fat] of the body burden reference values of a not particularly exposed population show detectable deviations in these immunological variables, when compared with persons at the lower and medium range [1-3 ppt TCDD or 9-29 ppt I-TE] of these body burden reference values. Regression analysis of our data revealed slight trends for some of the biomarkers (e.g. CD45R0+). With one exception, these were all increases. None of the alterations observed are of medical relevance. The slight increase in the percentage of CD4+CD45R0+ cells remained significant even after covariant analysis taking age-related changes into account. Altogether, the data do not provide any evidence to support an assumption that moderately increased body burdens of PCDDs/PCDFs in adults induce decreases in the cellular components of the human immune system. Adult humans certainly are less susceptible to this action of PCDDs/PCDFs than adolescent Callithrix jacchus.

Adult↗

Teacher ratings of student risk for substance use as a function of specialized training.

The purpose of this study was to determine if teachers' abilities to identify accurately students who are at risk for substance abuse can be improved through attendance at a specialized training program. Sixty-three eighth-grade teachers participated in the study. Of these, thirty-six teachers participated in the training sequence (intervention group), while the remaining twenty-seven teachers served as a comparison group. All eighth-grade students in the school district were surveyed regarding their substance usage. Teachers rated the students regarding their risk for substance usage. Teachers' ratings and students' reported substance usage were compared to assess the percentage of matching responses. After training, the intervention teachers provided more accurate ratings among usage categories than did the comparison teachers. The trained teachers were better at correctly identifying the students who were at risk for substance use.

Adolescent↗

A low-spin iron complex in human melanoma and rat hepatoma cells and a high-spin iron(II) complex in rat hepatoma cells.

Human melanoma and rat hepatoma cells cultured in the presence of low concentrations (2.5 microM) of low-molecular-weight iron (Fe) chelates and Fe-transferrin complexes have been studied with 57Fe Mössbauer spectroscopy. The spectra show that holoferritin is only a minor fraction of the total iron present in the cells. The major form of Fe was in a low-spin state unlike the high-spin Fe(III) found in ferritin. Only about 10% of the Fe could be attributed to ferritin. In addition, the hepatoma cells had a high-spin Fe(II) spectral component which made up about 20% of the Fe present.

Animals↗

Calcium biomineralization in the radular teeth of the chiton, Acanthopleura hirtosa.

A method has been devised for isolating the calcium biomineral from the iron biominerals and organic components present in the major lateral teeth of the chiton Acanthopleura hirtosa. Fourier-transform infrared spectroscopy of the calcium biomineral indicated that it was an apatite material containing carbonate and fluoride ions. Carbonate was not found to be present as a separate phase. The apatite was further separated into low and high density fractions, both of which showed crystallinity intermediate between that of bovine tibia cortical bone and human tooth enamel, as indicated by powder X-ray diffraction analysis. The calcified region of the major lateral teeth was also studied in situ using transmission electron microscopy and electron diffraction analysis, revealing a close spatial relationship between the mineral apatite phase and underlying organic matrix. It is suggested that the architectural arrangement of apatite biomineral and fibrous organic constituents imparts specialized mechanical properties to the tooth making it ideally suited for the task of obtaining food from hard surfaces.

Animals↗

Noninfectious osteitis: part of the SAPHO syndrome.

SAPHO, a rare syndrome, is a recently suggested acronym for synovitis, acne, pustulosis, hyperostosis and osteitis. It encompasses many features which have been described in different but overlapping conditions. Not all of the syndrome components need to be present for inclusion in SAPHO to be justified, especially the dermatologic components. Two cases are described as examples. Clinicians should be aware of this rare disorder if positive early diagnoses are to be made in patients presenting with skeletal pain.

Acne Vulgaris↗

Comparison of three methods of antibiotic prophylaxis in knee arthroplasty.

Prophylactic intravenous cefamandole nafate was administered by the systemic, systemic with probenecid (causing renal tubular blockade of antibiotic excretion), and intravenous regional routes. Bone antibiotic levels were assayed 15 minutes and 12 hours after administration, and hematoma concentrations after 8 hours. Bone concentrations after intravenous regional administration were significantly greater than systemic after 15 minutes, but were not detectable after 12 hours. Probenecid produced inhibitory concentrations in bone after 12 hours and also increased hematoma antibiotic concentrations to three times those achieved by systemic administration. Adequate prophylaxis may be possible with two rather than three doses of cefamandole if probenecid is used.

Cefamandole↗

Use of an aquatic light trap for monitoring larval population of Culex quinquefasciatus (Diptera: Culicidae).

An aquatic light trap was evaluated in wading pools placed in a greenhouse as a method of sampling populations of mosquito larvae. Three replicated experiments examined the effect of the color of a Cyalume light source and the vertical placement of the trap within the water column. Traps placed with the entrance funnel opening at the surface of the water collected significantly more fourth-instar Culex quinquefasciatus than did those with the entrance submerged. When traps were placed near the surface of the water, those with blue, yellow, and white light sticks, as well as unlighted control traps, collected approximately the same number of larvae. Therefore, a small change in trap position was more important than the presence of a light source in the effectiveness of this aquatic light trap as a sampling device for mosquito larvae.

Animals↗

Antibodies to histones in systemic lupus erythematosus: prevalence, specificity, and relationship to clinical and laboratory features.

Antibodies to histones (AHA) are commonly found in patients with systemic lupus erythematosus (SLE). However, the full profile of AHA and their clinical associations remains unclear. A total of 111 patients with SLE were studied, including 13 patients in whom multiple serum samples were available over several years. IgM, IgG, and IgA antibodies to total core histones, histone complexes, and individual histones were determined by highly sensitive enzyme linked immunosorbent assays (ELISAs). Antibodies to histones were detected in 74% of serum samples, though only at low levels in half of these. Antibodies to each of the individual histones (H1, H2A, H2B, H3, H4) occurred with similar frequencies except for IgG and IgA antibodies to H4, which were uncommon. In contrast, antibodies to the histone complexes H2A-H2B and H3-H4 were detected in only two serum samples and thus do not appear to be a feature of SLE. All three major isotypes of AHA were common and usually occurred with similar frequencies to one another for the various histone specificities. There were few clinical or laboratory associations with AHA; the strongest was between IgG antibodies to total core histones and antibodies to native DNA. Similarly, there was no association between the presence of AHA and disease activity. However, for the patients as a group and in one patient alone, periods of SLE disease activity were associated with higher levels of AHA. Although the profile of antibodies to individual histones varied with time, no profile was identified that corresponded with any specific disease manifestations. It is concluded from this study that although AHA are common in patients with SLE, their clinical value in this syndrome must, at present, be considered limited.

Adolescent↗

Acromioclavicular disruption in first class rugby players.

In a random sample of 105 first class rugby players, 45% gave a history of injury of the acromioclavicular joint. All continued to play at the highest level. The effects of the injury appeared to be minimal. Supraspinatus impingement syndrome commonly associated with acromioclavicular pathology was sought, but not found.

Acromioclavicular Joint↗

Organ-specific crystalline structures of ferritin cores in beta-thalassemia/hemoglobin E.

The cores of ferritins isolated from different organs of human subjects with beta-thalassemia/hemoglobin E (beta-thal/HbE) disease have different size distributions and crystallinities depending on the source organ. These patients have not been treated by hypertransfusion regimen or iron chelation therapy. beta-Thal/HbE spleens and livers yield ferritin cores which are less crystalline than those isolated from normal spleens and livers, reflecting the more rapid deposition of iron in the diseased state. Ferritins isolated from the hearts and pancreases of beta-thal/HbE subjects were found to have larger, more crystalline cores than those from the beta-thal/HbE livers and spleens, possibly as a consequence of the role of the heart and pancreas as long-term iron deposition sites in this iron overload pathology.

Ferritins↗

Stepped potential microcoulometry of ferritin.

A coulometric method for measuring the redox potentials of ferritins and the rates of reduction of the iron core is reported. The half-reduction potential, Eo', of the protein is determined from the coulomb-applied potential curve. This curve is obtained from the difference between the curves for the mediator plus protein and the mediator alone. The coulomb-applied potential curves are generated by stepping the potential in increments over the region of interest and measuring the charged passed following each step. The method is reasonably fast, enabling the redox potential to be determined in 1 day, and gives Eo', values for mediators and the protein that are in good agreement with literature values.

Electrochemistry↗

Ontogeny of monooxygenase activities in the marmoset monkey (Callithrix jacchus).

The pre- and postnatal development of monooxygenases in the liver and adrenal gland of marmoset monkeys (Callithrix jacchus) was investigated. Cytochrome P450 was detected in the fetal adrenal gland, but aldrin epoxidase, ethoxycoumarin O-deethylase, and ethoxyresorufin O-deethylase activities were below detection limits. Although fetal hepatic cytochrome P450 was not detected, low activities of aldrin epoxidase and ethoxycoumarin O-deethylase, but no ethoxyresorufin O-deethylase, could be detected in fetal liver. These enzymes attained adult marmosets activities when the offspring were approximately 2 months of age.

7-Alkoxycoumarin O-Dealkylase↗

Red cell and plasma calcium, copper and zinc in beta-thalassemia/hemoglobin E.

Beta-thalassemia/Hb E is a genetic disease prevalent in Thailand. This study has used atomic absorption spectroscopy to evaluate red cell and plasma calcium, copper and zinc in patients with beta-thalassemia/Hb E, both splenectomized and non-splenectomized. The levels of these trace elements in both red cells and plasma were different between the non-thalassemic controls and the disease patients. The most prominent result was that calcium concentration in red cells increased significantly in thalassemia subjects, particularly in splenectomized cases. These results might reflect the abnormal trace element metabolism and defects in the calcium transport system of the red cell membrane in thalassemia.

Adult↗