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Biomedical subjects

R Hadfield

Publications and source records attributed to R Hadfield.

12 recordsLinked to original sources
PubMed1998

The natural history of fetomaternal alloimmunization to the platelet-specific antigen HPA-1a (PlA1, Zwa) as determined by antenatal screening.

Immunization against the human platelet antigen (HPA)-1 alloantigen is the most common cause of severe fetal and neonatal thrombocytopenia. Fetal therapy has substantial risks and its indications need better definition. Of 24,417 consecutive pregnant women, 618 (2.5%) were HPA-1a negative of whom 385 entered an observational study. All were HLA-DRB3*0101 genotyped and screened for anti-HPA-1a. Their partners and neonates were HPA-1 genotyped and the latter were assessed by cord blood platelet counts and cerebral ultrasound scans. Anti-HPA-1a was detected in 46 of 387 pregnancies (12.0%; 95% CI 8.7%-15.2%). All but one were HLA-DRB3*0101 positive (odds ratio 140; 95% CI 19-1035; P< .00001). One baby died in utero, and of 26 HPA-1a-positive babies born to women with persistent antenatal antibodies, 9 were severely thrombocytopenic (8 with a count <10 x 10(9)/L, 1 with a large porencephalic cyst), 10 were mildly thrombocytopenic, whereas 7 had normal platelet counts. Severe thrombocytopenia was significantly associated with a third trimester anti-HPA-1a titer >/= 1:32 (P = . 004), but was not observed in babies of women with either transient or postnatal-only antibodies. HPA-1a alloimmunization complicates 1 in 350 unselected pregnancies, resulting in severe thrombocytopenia in 1:1,200. HPA-1a and HLA-DRB3*0101 typing combined with anti-HPA-1a titration allows selection of the majority of pregnancies at risk of severe thrombocytopenia.

Abortion, Spontaneous↗
PubMed1996

A whole blood assay for platelet HPA1 (PLA1) phenotyping applicable to large-scale screening.

Any future programme of antenatal screening of pregnancies for risk of neonatal alloimmune thrombocytopenia will have as a major requirement the availability of cost-effective assays which can be applied to large numbers of samples. To address this, we developed a competitive ELISA to type whole blood samples for the platelet alloantigen HPA1a, based on the use of purified glycoprotein (GP) IIb/IIIa from donors of known HPA1 genotype along with well characterized anti-HPA1a antiserum. Microtitre plates were coated with purified GPIIb/IIIa from donors of genotype HPA1a1a/3a3a. Anticoagulated whole blood of unknown HPA1 type was added to each well followed by anti-HPA1a. Residual antiHPA1a antibody not bound to the platelets in the test blood sample, bound to the immobilized HPA1a on the plate and was quantitated by standard ELISA. 475 blood donors were typed by the assay and the results compared in a blinded comparison with typing in the Capture-Ptm assay. Concordance was 100% (468 HPA1a positive and seven HPA1a negative). The HPA1 type of control samples stored as whole blood could be discriminated by this assay for up to 23 d of storage at 4 degrees C. This assay should be suitable for use in large-scale population screening programmes.

Antigens, Human Platelet↗
PubMed1996

Delay in the diagnosis of endometriosis: a survey of women from the USA and the UK.

We investigated the length of time between the onset of pain symptoms and the surgical diagnosis of endometriosis in women from the UK and the USA. A total of 218 women with surgically confirmed disease, recruited through endometriosis self-help groups, completed a postal questionnaire. The mean +/- SD delay in diagnosis for women from the USA was 11.73 +/- 9.05 years, significantly higher than the equivalent delay of 7.96 +/- 7.92 years for women from the UK (P < 0.01). The stage of disease did not effect the length of time between the onset of symptoms and diagnosis. Therefore there is considerable delay in the diagnosis of endometriosis for women from both the UK and the USA. Efforts to reduce this delay are required to minimize the suffering of women with this disease.

Adult↗
PubMed1986

Computed tomographic three-dimensional localization and compositional evaluation of intraocular and orbital foreign bodies.

A software program designed for the Siemens Somatom DR3 computed tomographic (CT) scanner provides improved diagnosis, localization, and etiologic description of intraocular and orbital foreign bodies. The program allows information to be analyzed in two different display formats. One format is that of multiplanar reconstruction of the eye and orbit, including an "oblique CT cube" image. This format produces an accurate "three-dimensional" display of both in vitro and in vivo intraocular and orbital foreign bodies. The second display format is that of a histogram. Using this analytic mode, nonmetallic intraocular and intraorbital foreign bodies can be differentiated from each other and from metallic foreign bodies, although individual metallic foreign bodies cannot be identified with respect to specific composition. The information provided by these two display formats substantially aids the clinician in the diagnosis and management of foreign bodies located within the orbit, particularly those located within the eye.

Animals↗
PubMed1986

Sequential computed tomographic imaging of a transplantable rabbit brain tumor.

The accuracy of CT imaging in evaluating VX-2 tumor growth in the rabbit brain was assessed. CT scanning was performed in 5 outbred New Zealand white male rabbits before and at 4, 7, 9 and 13 (in 3 animals) days after surgical implantation of 3 X 10(5) viable VX-2 tumor cells in the frontoparietal lobes. The CT studies were correlated with gross pathology in each. The tumor was visualized with CT in all 5 rabbits by the 9th day post implantation when the tumor ranged in size from 4-6 X 3-4 X 2-3 mm. Between the 9th and 13th day, the tumor increased 6-fold in two rabbits and 12-fold in the third rabbit. CT is a useful technique to evaluate brain tumor growth in this model and should be valuable in documenting the efficacy of chemotherapy on tumor growth.

Animals↗
PubMed1986

Multiplanar (MPR) imaging of the hip.

Multiplanar CT expands the ability of the radiologist to define the extent of disease, to suggest appropriate surgery, and to offer a probable prognosis.

Acetabulum↗
PubMed1980

Contribution of an educational phase to stress inoculation of speech anxiety.

A study is described in which students anxious about speeches were treated by variations of stress inoculation training. The purpose of the experiemnt was to evaluate the contribution of an educational phase to the training. Three treatment groups received either the educational phase only, the skills phase only, or both. These were compared with a no-treatment control group. The education-only group was the only group to improve significantly on self-reported anxiety measured before giving a public speech. The education-only and combination group imporved on self-reported self-efficacy as a speaker. All groups improved on behavioral rating of anxiety. Discussion focuses on the apparent potency of using an educational model in the treatment of anxiety. Future research is suggested for delineating the conditions under which education is a powerful ingredient.

Anxiety↗