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Biomedical subjects

J Webb

Publications and source records attributed to J Webb.

At least 19 recordsLinked to original sources

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

Nonpharmacologic interventions for pain management.

Managing pain is a complex and inexact science. Acute and chronic pain physically and psychologically affects and disables an overwhelming number of people. Nonpharmacologic interventions for pain management have been reviewed. These methods can be used independently or in combination with other nonpharmacologic or pharmacologic methods of pain control. The goals of nonpharmacologic interventions for pain management include the reduction of pain, minimal adverse effects, and allowing patients to become active participants in their own care. Nurses are called on many times to comfort patients in pain. It is through their expertise and intervention that the goals of pain management succeed.

Acupuncture Therapy

Assertive community treatment for frequent users of psychiatric hospitals in a large city: a controlled study.

Evaluated a large-city adaptation of the assertive community treatment (ACT) model (Stein & Test, 1980). Outcomes were examined after 1 year for 82 clients, averaging over 17 lifetime psychiatric hospitalizations, randomly assigned either to ACT or to a drop-in (DI) center. After 1 year, 76% of the ACT clients and only 7% of DI clients were involved in the respective programs. The ACT team averaged 2 home and community visits per week to each client. ACT clients averaged significantly fewer state hospital admissions and state hospital days than did DI clients. ACT clients reported greater satisfaction with program services, fewer contacts with the police, and less difficulty with practical problems associated with psychiatric readmission. More ACT clients were known to have stable community housing. Annual per-client treatment costs for ACT were estimated to be $1,500 less than for DI.

Adolescent

Beta-thalassaemia/haemoglobin E tissue ferritins. I: Purification and partial characterization of liver and spleen ferritins.

Ferritins from liver and spleen of both beta-thalassaemia/haemoglobin E (HbE) and non-thalassaemic patients were purified by heating a methanol-treated homogenate, followed by molecular exclusion chromatography. The concentrations of ferritins in the beta-thalassaemia/HbE liver and spleen were calculated as 3.8 and 2.0 mg/g wet tissue. The beta-thalassaemia/HbE ferritin iron/protein ratios were higher than those of normal ferritins. On PAGE, all ferritins gave a single major monomeric band with only very small differences in their mobility. Ferritins from thalassaemic patients also possessed bands corresponding to oligomers. On SDS/PAGE, all ferritins were resolved into two major subunits: H and L with L subunit predominating. While the isoferritin profiles of ferritins from beta-thalassaemia/HbE liver and spleen were similar to each other and to those of normal liver and spleen, some extra bands were present in the acidic region. The microstructure of these pathological ferritins appears to result, to a large degree, from the particular nature and amount of iron loading present.

Electrophoresis, Polyacrylamide Gel

Beta-thalassaemia/haemoglobin E tissue ferritins. II: A comparison of heart and pancreas ferritins with those of liver and spleen.

Tissue ferritins from beta-thalassaemia/haemoglobin E heart and pancreas were characterized by native PAGE, SDS/PAGE and isoelectric focussing, and compared with those isolated from corresponding liver and spleen tissue. On PAGE, all ferritins consisted of a single band assigned to the protein monomer. Small differences in electrophoretic mobility were found between the bands. The ferritins were resolved by SDS/PAGE into two major subunits, H and L, corresponding to molecular masses of 22.5 kDa and 19 kDa, respectively. The L subunit was predominant in all cases. The isoferritin profiles of all tissue ferritins were remarkably similar, consisting of a complex pattern of bands which were appreciably more basic than those obtained for horse spleen ferritin. The subunit composition and isoferritin profiles of the four tissue ferritins almost certainly reflect the defense mechanism of the body in synthesizing in all four tissue types a more stable long-term iron-storage isoferritin in order to detoxify and store the excess iron present due to the pathological condition of beta-thalassaemia/HbE.

Electrophoresis, Polyacrylamide Gel

Activity of aldrinepoxidase, 7-ethoxycoumarin-O-deethylase and 7-ethoxyresorufin-O-deethylase during the development of chick embryos in ovo.

Since the chick embryo in ovo is susceptible to the action of some agents needing metabolic activation we studied the development of the activity of cytochrome P450-dependent monooxygenases in embryo/fetal tissue. The activities of aldrinepoxidase (AE), 7-ethoxycoumarin-O-deethylase (ECOD) and 7-ethoxyresorufin-O-deethylase (EROD) were measured in whole embryos, liver and yolk sac tissue of the chick embryo during development in ovo from day 4 to day 15 of incubation (DI). In yolk sac tissue enzyme activities could be detected from DI 4 on. While EROD activity was only marginally developed, AE and ECOD activities were more pronounced in the earlier developmental period and showed a clear decrease by the time the liver activities rose. With the methods used AE activity could be measured in the homogenate of the whole embryo proper from DI 4 on while EROD and ECOD activity was not detectable before DI 6 or DI 7, respectively. In liver tissue enzyme activities of the three monooxygenases studied developed to a considerable degree from DI 9 on and tended to exhibit maximum values around DI 11-13. Studies on monooxygenase activities in extra-embryonically located tissues have not been published until now. The importance of the yolk sac as a metabolically relevant organ during embryogenesis is pointed out in this study.

7-Alkoxycoumarin O-Dealkylase