Platelet interactions with fibronectin: divalent cation-independent platelet adhesion to the gelatin-binding domain of fibronectin

Divalent cation-dependent platelet adhesion to fibronectin (FN) is mediated by the integrin receptors alpha 5 beta 1 (GP Ic-IIa) and alpha IIb beta 3 (GP IIb-IIIa), which recognize the RGD (Arg-Gly-Asp) sequence in the cell-binding domain. However, FN can also support divalent cation-independent platelet adhesion. To determine which domain of FN mediates divalent cation-independent adhesion, proteolysis with thermolysin and affinity chromatography were used to isolate the cell-binding, gelatin-binding, and heparin-binding domains of FN. Unactivated and thrombin-activated platelets adhered to intact FN and the 45-Kd gelatin-binding domain in the presence of either Ca2+ or EDTA. Platelet spreading was mediated only by the 105-Kd cell-binding domain and required divalent cations. The heparin-binding domains did not support platelet adhesion. Reduction of intrachain disulfide bonds or removal of carbohydrate side chains on the gelatin-binding domain did not alter the ability to support platelet adhesion. Divalent cation- independent adhesion to the 45-Kd gelatin-binding domain was not inhibited by RGDS (Arg-Gly-Asp-Ser) synthetic peptides or monoclonal antibodies (MoAbs) directed against known platelet receptors. We conclude that platelets can adhere but not spread on the gelatin- binding domain of FN by a novel divalent cation-independent mechanism.     

Neutrophil surface markers in patients with acute leukemia

The presence of complement and Fc receptors on neutrophils from patients with acute leukemia was investigated at different stages of the leukemic process. Both Fc receptors (Fc-H and Fc-R) and one complement receptor (C3d) were normal when patients were studied at diagnosis, in relapse, and in remission. In contrast, the C3b receptor was significantly reduced on te neutrophils at the time of diagnosis, but returned to normal levels when patients entered remission. Variable amounts of C3b activity were observed in patients relapse, with approximately one-half of the patients showing decreased C3b activity. To determine whether the reduction inC3b receptors was specific for patients at diagnosis, three patients were studied at different times during their diseases. Normal receptor levels were detected in these patients during remission, but the C3b receptor was markedly reduced at diagnosis and at relapse.     

High glucocorticoid receptor content of leukemic blasts is a favorable prognostic factor in childhood acute lymphoblastic leukemia

We have previously shown that the number of glucocorticoid receptors (GR) per cell in malignant lymphoblasts from children with newly diagnosed pre-B- and early pre-B-cell acute lymphoblastic leukemia (ALL) has a positive correlation with the probability of successful remission induction (Quddus et al, Cancer Res, 45:6482, 1985). We report now on the long-term outcome for these patients treated on a single protocol with 3 different treatment arms, all of which included glucocorticoid pulses during maintenance therapy. GR were quantitated in leukemic cells from 546 children with ALL at the time of diagnosis. Immunophenotyping studies were performed on all specimens. Prior studies showed that in pre-B- and early pre-B-cell ALL, successful remission induction was associated with a median GR number of 9,900 sites/cell, whereas induction failure was associated with a median receptor number of 4,800 sites/cell. Long-term follow-up of these patients shows an association between higher GR number and improved prognosis. The 5-year event-free survival of 61.0% (SE 2.8%) for patients whose leukemic cells had greater than 8,000 receptors/cell and 47.3% (SE 3.3%) for those with less than 8,000 receptors/cell is significantly different (P < .001). This difference remains significant when adjusted multivariately for blast immunophenotype and clinical risk factors (P < .001) or for treatment type (P < .001). We conclude that GR number greater than 8,000 sites/leukemic cell is a favorable prognostic marker for children with acute lymphocytic leukemia. This finding offers deeper insights into molecular mechanisms of anti- leukemia therapy and suggests that manipulation of steroid receptor number might augment the antitumor response, thus opening new avenues for basic and clinical research.     

Spectrin Tunis (Sp alpha I/78), an elliptocytogenic variant, is due to the CGG----TGG codon change (Arg----Trp) at position 35 of the alpha I domain

Spectrin Tunis (Sp alpha I/78) is an alpha l domain variant that causes asymptomatic elliptocytosis in the heterozygote state. It is manifested by a reduction of spectrin dimer self-association and by the development of a major 78-Kd fragment at the expense of the alpha l 80- Kd fragment upon spectrin-limited digestion. Amino acid sequence analysis, following peptide transfer onto Immobilon membranes, showed that the 78-Kd fragment results from a sensitized cleavage after lysyl residue 10. Using a 13.5-kb genomic alpha-spectrin probe and the Xbal, Pvull, and Mspl polymorphic sites detected with this probe, we concluded that spectrin Tunis is associated with the + - + haplotype (in the above order). Twenty mer oligonucleotides, complementary to genomic segments from introns 2 and 3, respectively, were synthesized. We then performed DNA amplification and sequencing. In the two investigated carriers of spectrin Tunis, we found the C----T base substitution of the codon corresponding to position 35 of the alpha l domain (CGG----TGG; Arg----Trp). The mutation lies in the last part of an alpha helix that extends from residues 9 to 44 of partial repeat alpha 1' and is comparable with helix 3 of full repeats 1 to 5. The modified proteolytic site, located 25 amino acid residues upstream, occurs at the beginning of the helix.     

Leiomyomas in pregnancy: sonographic study

With ultrasound monitoring, analysis of the behavior of uterine leiomyomas (fibroids) and their impact on the course of pregnancy was undertaken in a group of 113 patients. Fibroid size changes were analyzed on the basis of trimesters. In the second trimester, smaller fibroids increased in size, whereas larger fibroids decreased in size. In the third trimester, a decrease in size was documented regardless of initial size. The most common patterns of echotexture were hypoechoic, heterogeneous, and echogenic rim. The development of a heterogeneous pattern or anechoic/cystic spaces on a follow-up study was accompanied in seven of ten patients by severe abdominal pain, compared with 12 cases of abdominal pain in 103 patients without such echotexture changes. Although the number of patients was small, the development of these patterns apparently indicates significant degeneration of the fibroid. Fibroids located in the lower uterine segment were accompanied by a higher frequency of cesarean section and retained placenta. Fibroids located in the uterine corpus were more frequently associated with early abortions. Multiple fibroids were accompanied by a higher frequency of malpresentation and premature contractions compared with cases with one or two fibroids.     

Using the theory of planned behaviour to develop an assessment of attitudes and beliefs towards prosthetic use in amputees

Purpose:?To develop a questionnaire based on the theory of planned behaviour (TPB) to predict prosthetic use.

Method:?In part one, 31 amputees over 50 years of age with peripheral arterial disease completed attitude items containing 27 bipolar adjectives and open-ended questions on behavioural, normative and control beliefs relating to using the prosthesis. Academic, clinical and patient experts (n?=?12) identified bipolar adjectives with best face validity. In part two, 15 amputees completed three behavioural format questions relating to prosthetic use and were asked to indicate the easiest to answer.

Results:?Following the completion of the attitude items by the amputees and the expert panel review, 5 items remained (Cronbach's alpha?=?0.87) with corrected item-total correlations ranging from 0.43 to 0.83. Modal behavioural beliefs concerned mobility (46.5%), independence (25.6%) and participation restrictions (16.3%), normative beliefs concerned family (33.3%), NHS staff (31.7%), friends (19.1%) and other patients (15.9%) and control beliefs concerned stairs (21.1%), slippery/rough surfaces (28.9%), disabled facilities (54.8%) and people helping (22.6%). In relation to part 2, an exact numerical report of hours and days of prosthetic use was found easiest to answer (73%).

Conclusions:?Based on this qualitative and quantitative development work, the questionnaire contains five attitude items, six behavioural, eight normative, eight control belief items and two self-report questions of the behaviour.     

Perception of anatomical structures in digitally filtered and conventional panoramic radiographs: a clinical evaluation

Objectives

The aims of the study were to compare subjective image quality of clinical images obtained with a storage phosphor plate (SPP)-based digital and conventional film-based panoramic system for the visualization of various anatomical structures and to evaluate the effect of various processing algorithms on image interpretation.

Methods

Panoramic radiographs were taken in 42 patients both with film and with a SPP system. SPP images were treated with shadow, sharpen, negative, greyscale sigma and greyscale exponential filters. Four observers subjectively evaluated films and unfiltered and filtered SPP images for the visibility of anatomical structures with various radiodensities as well as for overall image quality on a three-point rating scale. The statistical methods used were Kruskal–Wallis, odds ratio analysis and Cohen''s kappa.

Results

No statistically significant difference was found between film and unfiltered digital images except for low-contrast structures (P > 0.05). Film images were preferred for the visibility of low-contrast structures (P < 0.05). Best overall image quality was obtained with sharpened images (P < 0.05) followed by films and unfiltered digital images. Among all filtered images, sharpened ones received the highest ratings for the visibility of all anatomical structures (P < 0.05). The intra- and interobserver agreement ranged between moderate and substantial and between fair and moderate, respectively.

Conclusions

Film and unfiltered SPP-based panoramic images performed equally well in terms of overall quality; however, films were best for the perception of low-contrast structures. The sharpening filter may be recommended for enhancing SPP panoramic images to improve the visual perception of most of the anatomical structures as well as overall quality.