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Biomedical subjects

S Dale

Publications and source records attributed to S Dale.

At least 37 records · Page 2Linked to original sources
PubMed1990

Digital amputations in neuropathic feet.

A retrospective study was performed on 26 patients who had undergone 27 digital amputations. All of the patients in the study had marked neuropathy. Sixty-five percent of the feet developed new ulcerations following initial hallux amputations, with 53% of the ulcerations occurring at distal digital sites. Fifty-three percent of the patients who had undergone hallux amputations required further amputations secondary to new ulcerations. In contrast, only 10% of the feet with initial lesser digit amputations developed new ulcerations. The authors discuss the biomechanics involved and the possible therapy for preventing these ulcerations and amputations.

Alcoholism↗
PubMed1990

Tomography using a rotating slant-hole collimator and a large number of projections.

A tomographic method using a limited-view angle has been evaluated. In studies using a gamma camera and a rotating 30-degree slant-hole (RSH) collimator, 64 projection images were registered. A special filtered backprojection technique was used for reconstruction of section images parallel to the collimator face. Resolution within such sections was 0.6 cm, 3 cm from the collimator face and 1.3 cm at 18 cm. Depth resolution was 2.2 cm at 3 cm and 5.1 cm at 18 cm. Spacing between section images was regular and geometric distortion negligible. Short-axis section images of a myocardium in vivo were qualitatively comparable or better than those obtained with single-photon emission computed tomography. Degradation in the posterior wall due to attenuation and scatter was less. Section images of the facial bones and a hip joint further demonstrated the tomographic capability of the method.

Algorithms↗
PubMed1990

Thallium-201 myocardial tomography with a rotating slant-hole collimator and a large number of projections.

Tomographic imaging of the myocardium was performed using a gamma camera and a 30-degree rotating slant-hole collimator to register 64 projections from a restricted-view angle. Section images were reconstructed with a two-dimensional filtered backprojection technique. Performance in terms of resolution, effects of misalignment, and three-dimensional activity distribution was evaluated in phantom studies. In a limited clinical study, ten consecutive patients were imaged both with single-photon emission computed tomography (SPECT) and the method described. In the new method, the camera was orientated in the 30 degrees left anterior oblique position with 15 degrees cranial tilt. Due to the short distance from the myocardium to the camera, resolution within reconstructed section images was high, the noise level was comparatively low, and the mean activity level in the posterior wall was significantly higher (p less than 0.005) than in SPECT.

Heart↗
PubMed1989

Centromeric alpha satellite DNA amplification and translocation in an unusually large chromosome 14p+ variant.

We report cytogenetic and molecular studies on a family that carries, in the father, an unusually large chromosome 14p+ variant [WSi-var(14)(p+)] and, in one of his children, a translocation [DSi-der(14)] involving the variant chromosome. Increase in the size of WSi-var(14)(p+) was estimated to be approximately 35% that of a normal chromosome 14. Presence of extra chromosomal material in this variant chromosome was demonstrated by G-banding using trypsin and staining with Leishman, G-banding using bromodeoxyuridine (BrdU) and Giemsa, and R-banding using BrdU and Giemsa. This material was positive using C-banding with BaOH and staining with Giemsa and negative in DAPI/distamycin staining, suggesting that it contained repetitive DNA but probably not of the types found in the heterochromatic regions of chromosomes 1, 9, 15, 16, and Y. Staining of the nucleolus organiser region (NOR) with AgNO3 indicated the retention of the NOR in WSi-var(14)(p+) but not in DSi-der(14). In situ hybridisation of metaphase cells with an alpha satellite DNA probe specific for human acrocentric chromosomes demonstrated a significantly increased amount of centromeric alpha sequences in WSi-var(14)(p+). Most or all of the extra alpha sequences were retained in DSi-der(14), indicating translocation near the very distal end of the enlarged region. The extra alpha satellite DNA material may have originated through amplification of some centromeric segments. The possible role of the amplified DNA in chromosomal translocations is discussed.

Chromosome Banding↗
PubMed1989

Amplification of satellite III DNA in an unusually large chromosome 14p+ variant.

A phenotypically normal male (WSm) was found to have an unusually large short arm of chromosome 14. Increase in the size of this variant chromosome [Wsm-var(14)] was estimated to be approximately 30% that of a normal chromosome 14 by G-banding using trypsin and staining with Leishman. The extra chromosomal material was positive in CBG staining (C-banding using BaOH and staining with Giemsa), suggesting the presence of repetitive DNA. In situ hybridisation using repetitive probes demonstrated this material to be strongly positive for satellite III DNA, and negative for Y-specific heterochromatic DNA. Hybridisation with an alpha DNA probe specific for human acrocentric chromosomes indicated the retention of the centromere, and the absence of alpha DNA in the extra chromosomal material. We propose the origin of the extra chromosomal material in WSm-var(14) to be a result of amplification of contiguous satellite III DNA that is normally present in the short arm of chromosome 14. This variant chromosome does not appear to be associated with the abnormal phenotype in WSm's daughter who is mentally retarded and carries a t(1;?)(q41;?) translocation of chromosome 1.

Chromosome Banding↗
PubMed1989

A study of tolerance to the psychomotor effects of indomethacin in healthy volunteers.

We have examined the effect of single dose indomethacin 50 mg on objective measurements of psychomotor function and whether this effect is altered by pretreatment with indomethacin 25 mg t.i.d. for 7 days in 10 healthy volunteers (5 male, 5 female; age 20-54 y). One hour after a single dose of indomethacin 50 mg there was significant impairment of psychomotor function (critical flicker fusion frequency threshold and choice reaction time) (Wilcoxon p less than 0.05). Pretreatment with indomethacin 25 mg t.i.d. for 7 days prevented this impairment. Thus we conclude that tolerance occurs over the course of a week to the psychomotor effects of indomethacin.

Adult↗
PubMed1986

Purification and characterization of a major allergen from the house dust mite Dermatophagoides farinae.

A major allergen from an extract of the house dust mite, Dermatophagoides farinae, was shown to be extremely heterogenic with respect to charge. A slightly basic component of this allergen with a pI of 8, was purified by isoelectric focusing in two steps. The purified component, denoted antigen 19/20 IIa, seemed to be representative for the allergenic activity of the major allergen. The amino acid analysis suggested that antigen 19/20 IIa had a molecular weight of 9400 and contained one residue of galactosamine. SDS polyacrylamide gel electrophoresis did indicate a somewhat higher molecular weight of 14,500. Antibodies against the purified component cross-reacted with a crude extract of the mite Dermatophagoides pteronyssinus.

Allergens↗
PubMed1985

Ectomography--a tomographic method for gamma camera imaging.

In computerised gamma camera imaging the projections are readily obtained in digital form, and the number of picture elements may be relatively few. This condition makes emission techniques suitable for ectomography--a tomographic technique for directly visualising arbitrary sections of the human body. The camera rotates around the patient to acquire different projections in a way similar to SPECT. This method differs from SPECT, however, in that the camera is placed at an angle to the rotational axis, and receives two-dimensional, rather than one-dimensional, projections. Images of body sections are reconstructed by digital filtration and combination of the acquired projections. The main advantages of ectomography--a high and uniform resolution, a low and uniform attenuation and a high signal-to-noise ratio--are obtained when imaging sections close and parallel to a body surface. The filtration eliminates signals representing details outside the section and gives the section a certain thickness. Ectomographic transverse images of a line source and of a human brain have been reconstructed. Details within the sections are correctly visualised and details outside are effectively eliminated. For comparison, the same sections have been imaged with SPECT.

Brain↗
PubMed1985

Characterization of IgE and IgG antibody responses to Dermatophagoides farinae in rats.

Rats (Brown Norway/Wistar Fu) that were pretreated or not pretreated with cyclophosphamide were immunized with varying amounts of Dermatophagoides farinae allergen extract with alum as adjuvant. Sera were analysed by RAST and by crossed radioimmunoelectrophoresis (CRIE). The highest IgE antibody responses were recorded in animals pretreated with cyclophosphamide that had received low immunizing doses of antigen. The IgE antibody pattern in CRIE was, however, not influenced by the dose of antigen or by cyclophosphamide pretreatment. The IgG pattern in CRIE closely resembled the IgE pattern, demonstrating a similar specificity of the antibody responses of the two isotypes. This indicates non-class specific control of the specificity of antibody responses.

Animals↗
PubMed1984

A new, purified Dermatophagoides farinae allergen preparation. Evaluation with SPT and RAST techniques.

A purified, standardized and characterized allergen preparation of the house dust mite Dermatophagoides farinae (Df) was evaluated by skin prick test (SPT) and radioallergosorbent test (RAST) in 88 subjects. Skin reactions to the purified Df preparation and a corresponding crude Df preparation were compared. SPT was also performed with a crude Dermatophagoides pteronyssinus (Dpt) preparation to compare reactions obtained with the two mite preparations. By SPT the purified Df allergen preparation was representative of the crude Df preparation (r = 0.78) and the correlation between skin reactions to Df and Dpt was high (r = 0.78). The concordance between results obtained with RAST and SPT techniques with the purified Df preparation was high (84%). The purified D. farinae preparation was well tolerated and is well suited for SPT.

Allergens↗
PubMed1984

Characterization of allergens in a crude extract of Dermatophagoides farinae and their identification in a new purified preparation.

The allergens of a crude D. farinae extract were identified by means of crossed radioimmunoelectrophoresis (CRIE). A total of 11 allergens were identified. They were characterized as three major, three intermediate and five minor allergens, based on radiostaining in CRIE. In addition to the radiostaining due to allergens, some misleading radiostaining was observed associated with some of the other antigens. A purified commercially available preparation, Spectralgen Mite D. farinae, was compared with the crude extract by means of immunoelectrophoretic techniques and radioallergosorbent test (RAST) based techniques. The purified preparation was found to be fully representative of the allergens in the crude extract. All 11 allergens were identified in the purified preparation. The purification ratio of the allergens varied from 2 to 7, while the total specific allergenic activity was approximately 6 times higher in the purified preparation than in the crude extract, as judged from RAST-inhibition studies.

Allergens↗
PubMed1981

Antigens Common to Scabies and House dust Mites.

Twenty-five antigens were demonstrated in a crude Dermatophagoides farinae (DF) extract by means of crossed immunoelectrophoresis (CIE), using a rabbit anti-DF serum. With the same antiserum, four antigens were demonstrated in a scabies mite preparations, indicating an immunological relationship between these scabies antigens and some of the DF antigens. In tandem CIE experiments the DF antigens were found to be partly identical to three of the scabies antigens. No IgE activity against any of these scabies antigens was evident in pooled sera from patients with house dust mite allergy by crossed radioimmunoelectrophoresis. However, one such patient had IgE antibodies to a DF antigen and a partial identical scabies antigen.

Animals↗