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Biomedical subjects

D Barber

Publications and source records attributed to D Barber.

At least 127 records · Page 7Linked to original sources
PubMed1976

A purification procedure for the soluble cytochrome oxidase and some other respiratory proteins from Pseudomonas aeruginosa.

The production of the soluble cytochrome oxidase/nitrite reductase in the bacterium Pseudomonas aeruginosa is favoured by anaerobic conditions and the presence of KNO3(20g/l) in the culture medium. Of three methods commonly used for the disruption of bacterial suspensions (ultrasonication, liquid-shear homogenization and glass-bead grinding), sonication proved the most efficient in releasing the Pseudomonas cytochrome oxidase. A polarographic assay of Pseudomonas cytochrome oxidase activity with sodium ascorbate as substrate and NNN'N'-tetramethyl-p-phenylenediamine dihydrochloride as electron mediator is described. A purification procedure was developed which can be used on the small scale (40-litre cultures) or the large scale (400-litre cultures) and provides high yields of three respiratory-chain proteins, Pseudomonas cytochrome oxidase, cytochrome c551 and azurin, in a pure state. A typical preparation of 250g of Ps.aeruginosa cell paste yielded 180mg of Pseudomonas cytochrome oxidase, 81 mg of Pseudomonas cytochrome c551 and 275mg of Pseudomonas azurin.

Azurin↗
PubMed1976

Some spectral and steady-state kinetic properties of Pseudomonas cytochrome oxidase.

Some spectra of Pseudomonas cytochrome oxidase are reported, both for comparison with those of other workers and to illustrate the differences between the ascorbate- and dithionite-reduced forms of the enzyme. A spectrum of the reduced enzyme-CO complex, prepared in the absence of added reductants by incubation under CO, is also included. Ultracentrifugation studies yielded a value for the sedimentation coefficient (s20,w) of 7.5S, and an isoelectric point of pH6.9 was determined by isoelectric focusing. Steady-state kinetic constants of the electron donors, quinol, sodium ascorbate, reduced Pseudomonas azurin and Pseudomonas ferrocytochrome c551 were investigated giving Km values of 30mM, 4mM, 49muM and 5.6muM respectively. The two protein substrates were observed to be subject to product inhibition and the Ki for oxidized Pseudomonas azurin was evaluated at 4.9muM. Steady-state kinetics were also used to investigate the effects of the oxidation products of dithionite on the oxidase and nitrite reductase activities of Pseudomonas cytochrome oxidase. These experiments showed that whereas the oxidase activity was inhibited, the nitrite reductase activity was slightly enhanced.

Ascorbic Acid↗
PubMedDate not supplied

Is Lolium pollen from an urban environment more allergenic than rural pollen?

BACKGROUND: Allergy to grass pollen is a highly prevalent allergic disease. Hay fever is more predominant in urban than in rural areas, despite the increasingly smaller areas of surrounding grassland. The effect of vehicle exhaust pollutants, mainly diesel particles, and other industrial sources of atmospheric pollution leading to plant damage has been implicated in this phenomenon. OBJECTIVE: This study compared the in vivo and in vitro allergenicity of pooled samples of Lolium perenne grass pollen harvested from 10 different urban areas with that of samples of the same pollen from 10 neighboring rural areas. METHODS: Lolium perenne pollen from different parts of a city and from a nearby rural area was harvested in 1999 and 2000 during the peak pollination period. Protein composition was compared by SDS-PAGE and in vivo and in vitro IgE-binding capacity was compared by skin-prick tests, RAST-inhibition and measurement of the major allergen, Lol p 5. RESULTS: In the two years under study, urban samples contained approximately twice the protein content of the rural samples. Biological activity and Lol p 5 content was higher in urban pollen than in rural pollen and showed differences in the two years under study. CONCLUSIONS: The protein content and allergenicity of Lolium perenne pollen was higher in urban areas than in rural areas. These differences might explain why allergy to grass pollen is more prevalent in urban areas. This finding should be taken into account in diagnosis, preventive measures and specific immunotherapy.

Air Pollutants↗
PubMedDate not supplied

[Exposition and sensitization to Tyrophagus putrescentiae in a allergic population to Dermatophagoides pteronyssinus in Huelva, Spain].

BACKGROUND: In this work we analyzed the allergological importance of Tyrophagus putrescentiae (Tp) in Huelva (SE Spain). We studied the level of exposition and the grade of sensitization to Tp in a group of patients sensitized to Dermatophagoides pteronyssinus (Dpt). The allergenic cross-reactivity between Dpt and Tp was determined by RAST inhibition. METHODS AND RESULTS: We analyzed house dust samples from the dwellings of allergic patients with documented Dpt sensitization. Skin test (ST), conjunctival provocation (CP) and/or specific IgE (RAST) to Tp were performed when Tp was identificated in the house dust sample of the patient. Among the 136 dust samples studied, Dpt was the most frequently identified mite species (94.8%) and Tp was found in third position (41.1%) after Glycyphagus domesticus (54.4%). Among the 45 patients studied, 23 (51.1%) presented, at least, two positive tests, 18 (40%) were not sensitized to Tp and 4 (8.8%) showed contradictory results. 26 patients (57.7%) inhabited in urban areas and 19 (42.2%) in rural regions. We determined specific IgE (RAST) to Tp in 25 patients, and the results were positive in 12, with only 7 with values greater than 2 kU/L. No significant correlation were found between IgE-antibody levels to Dpt and Tp. The RAST inhibition studies confirmed the low cross-reactivity between these mites and only in one patient Dpt partially inhibited the IgE-binding to Dpt extract. CONCLUSIONS: Tp was the second more frequent storage mite in the house dust samples from patients allergic to Dpt in Huelva. However, only half of the exposed patients were sensitized to Tp and the majority inhabited in urban areas. No significant correlation were found between IgE-antibody levels to Dpt and Tp. The RAST inhibition studies confirmed the low cross-reactivity between these mites.

Acaridae↗
PubMedDate not supplied

A fertile field.

Explore the source record for details and available documents.

Career Choice↗
PubMedDate not supplied

Patterns of immunoglobulin E sensitization to chironomids in exposed and unexposed subjects.

We present our study of four patients with occupational type I allergy to red midge larvae (group 1) who we compared with seven individuals also sensitized to red midge larvae but who had not apparently been exposed to them (group 2). All patients showed elevated specific IgE against Chironomus thummi, and positive skin prick tests (SPT) and provocation tests with red midge larvae. We carried out SPT with Dermatophagoides pteronyssinus, Acarus siro, shrimp, cockroach and common mosquito (Culex pipiens) and specific serum IgE was also determined. The red midge larvae wheal size was significantly larger in group 1 (x = 149.2 mm2) than in group 2 (x = 18 mm2). Significant differences between levels of IgE anti-C. thummi were also found in group 1 (x = 52.12 kU/l) and in group 2 (x = 1.5 kU/l). The patients in group 2 had high levels of specific IgE against other allergens (D. pteronyssinus, shrimp and/or common mosquito) and had positive SPTs with these allergens, while the patients in group 1 were only sensitized to chironomids. The IgE-immunoblotting profile was quite different in both groups. The patients in group 1 seemed to have IgE against Chi t 1, the main Chironomus allergen, while the patients in group 2 had IgE against several protein bands in Chironomus, mosquito, shrimp and D. pteronyssinus extracts, some of them with equivalent molecular weights. We believe that the patients in group 2 were sensitized to Chironomus as a result of cross-reactivity with other insect or crustacean species.

Adolescent↗
PubMedDate not supplied

Cat allergen sampling by a new personal collector (Partrap FA 52).

Recent studies carried out by us and others have demonstrated that Fel d 1, the main cat allergen, may be passively transferred by human clothing in cat-free environments. Consequently, the monitoring of the Fel d 1 levels either in indoor environments or on allergen-contaminated clothes of sensitized cat owners should be considered an important tool in prevention strategies. The aim of this study was to evaluate the efficacy of a personal air sampler (Partrap FA 52) in capturing cat allergen from wool fabrics. Seven identical wool webs (80 x 100 cm) were put in the baskets of seven male cats for 1 week. In our laboratory each web was divided into two parts (80 x 50 cm), the first of which was then divided in two parts (40 x 50 cm) and each was vacuumed directly by one collector. The second part was dry-cleaned at a professional cleaners, divided in two parts and then vacuumed. For the dust collection from wool webs we used a fixed high volume air sampler (CF/20 Gelaire Flow Labs, Milan, Italy) and a personal collector (Partrap FA 52, Coppa Biella, Italy). Fel d 1 content was determined using a two site ELISA (ALK-Abelló Group, Madrid, Spain). Both air samplers collected cat allergens from cat-exposed wool fabrics before and after dry cleaning. There were significant differences between the levels of Fel d 1 before and after dry cleaning by using either CF/20 or Partrap FA52 and between the levels of Fel d 1 before dry cleaning using CF/20 and Partrap FA 52. The results of our study suggest that Partrap FA 52, although its air flow is half that of the CF/20, is able to collect even residual amounts of cat allergen from wool webs after dry cleaning and consequently may constitute a simple and effective means of monitoring the levels of Fel d 1 on the clothes of cat owners.

Air Pollution, Indoor↗
PubMedDate not supplied

Continuity of care in IVF: the nurse's role.

In this paper the author explains the process of in vitro fertilisation. She outlines the nurse's role in patient consultation and counselling at her unit in Oxford and the importance of that role in ensuring continuity of care.

Adult↗
PubMedDate not supplied

Hypersensitivity to chironomid larvae.

Chironomid larvae (red midge larvae) are often used by aquarists as fish food. Their hemoglobins can cause IgE-mediated allergic diseases in exposed and unexposed people. The aim of this study was to find out the prevalence of positive skin tests to chironomids in patients suffering from rhinitis and/or bronchial asthma in Ciudad Real (Spain). A total of 465 patients were submitted to skin prick tests with chironomids in addition to common inhalant allergens. The patients with positive skin prick test (wheal > or = 3 mm) to these larvae answered a questionnaire. Skin prick tests with Acarus siro, shrimp, cockroach and mosquito (Culex pipiens) were carried out. Serum levels of total IgE and anti-Chironommus thummi, anti-Dermatophagoides pteronyssinus, anti-shrimp, and anti-mosquito (Aedes communis) IgE were determined. Conjunctival or nasal provocation tests were carried out with chironomids. Of the 465 patients skin tested, 19 showed a positive skin prick test with chironomids, corresponding to 4.1% of all patients and 6% of the atopic patients. None were monosensitized. Significant correlations were found between skin prick test results with chironomids and mites (p < 0.005). Of the 19 patients, 15 had positive skin prick test with the common mosquito C. pipiens. Seven patients showed elevated anti-D. pteronyssinus IgE, six elevated anti-shrimp IgE, and 10 showed elevated anti-A. communis IgE. Provocation tests with chironomids were positive in 14 patients (four nasal and 10 conjunctival tests). Conjunctival provocation tests were carried out in 16 controls and were positive in three; all three showed positive skin prick test with chironomids. One patient had occupational allergy from the larvae (aquarist). After mosquito bites, five patients showed immediate wheal reactions and one patient suffered an anaphylactic reaction after several mosquito bites. Only two patients remembered having been in contact with chironomids as fish food. We found hypersensitivity to these larvae in patients without apparent contact to them. These patients could have become sensitized in various ways, including: 1) inhaling particles of chironomids or others that are cross-reactive with them; 2) exposure to products used as fish food containing chironomids; and, 3) through cross-reactivity with other allergens such as mites, shrimp or mosquitoes.

Adolescent↗