Transfected leukocyte integrin CD11b/CD18 (Mac-1) mediates phorbol ester-activated, homotypic cell:cell adherence in the K562 cell line

The CD11b/CD18 leukocyte integrin molecule mediates diverse neutrophil adherence-related functions, including cell:cell and cell:extracellular matrix attachments. To study the individual role of this leukocyte integrin in cell adherence in hematopoietic cells, we expressed the CD11b/CD18 complex on the surface of K562 cells, a cell line derived from an individual with chronic myelogenous leukemia in blast crisis. We used an amphotrophic retroviral vector designated LCD18SN, harboring the complete coding sequence for the CD18 subunit, to transfer the CD18 cDNA into K562 cells and select stable cell lines. The CD11b subunit in the expression plasmid pREP4 was transfected into these K562/CD18 cells by electroporation and stable cell clones were selected. These K562 cells possessed RNA and intracellular protein for each subunit, and they expressed the CD11b/CD18 heterodimer on the cell surface. When CD11b/CD18 expressing K562 cells were stimulated with phorbol myristate acetate (50 ng/mL) for 24 to 48 hours, these K562 cells formed dense cell:cell aggregates. This homotypic aggregation required both activation of the CD11b/CD18 complex and the induction of the counter- receptor for CD11b/CD18 on the conjugate cell. This cell line will (1) enable the structure-function relationships between cell activation and homotypic adherence to be assessed, (2) provide the opportunity to identify accessory molecules required for activation of the CD11b/CD18 complex, and (3) facilitate the identification of novel ligands for the CD11b/CD18 complex.     

The needs, concerns and coping of mothers of children with cystic fibrosis

The questionnaire CICI:PQ for measuring needs, concerns and coping of parents of chronically ill children was mailed to 85 families with children with cystic fibrosis (CF). Some questions about the parents' experiences of the health care system were also included. Fifty-four per cent responded--in all cases but two the mothers. More than half of the mothers wanted help with or opportunities to discuss the state of health and the emotional development of the child and dietary issues. Many of them were concerned about the child's future. Shortage of time was another problem. The coping strategies used when having problems with the child were partly different from those used when problems arose with the partly different from those used when problems arose with the spouse. Most mothers were satisfied with the hospital care and the CF paediatrician. They wanted further support from the physiotherapist and many of them missed a CF nurse. The project illuminated many areas for further investigation.     

The substance specificity of psychosocial correlates of alcohol, tobacco, coffee and drug use by Czech women

The paper reports results of an analysis based on face-to-face interviews with two samples of Prague women aged 20-49: (1) a probabilistic sample (h = 718) of the Prague female population; and (2) a sample of 152 inpatients treated for substance dependence/abuse. Of the inpatients, 79% were diagnosed as alcohol dependent only, 15% as both alcohol dependent and drug dependent/abusers, 6% as drug dependent only. With very few exceptions, those with drug problems among the inpatients abused analgesics, hypnotics, or anxiolytics. With data obtained from the general population sample, two-stage hierarchical logistic regression was run with each of the eleven differently defined substance uses as dependent variables. Four demographic variables were entered as predictors into the regression equations in the first stage. From the seven potential risk factors of substance use statistically significant predictors were entered stepwise in stage two. The major result of the study is the specificity of the pattern of predictors related to each of the eleven considered substance uses. It is also found that in the general population the use of a particular substance is generally uncorrelated with the use of other substances. Alcohol use (even heavy alcohol use) has no relation to smoking, to the use of analgesics, hypnotics, anxiolytics-and is connected with a specific pattern of predictors.     

Structural requirements of the oxytocin receptor in rat uterus

Published and newly calculated pA₂-values of 147 neurohypophyseal hormone analogues (7 positions varied) acting as inhibitors of oxytocin on isolated rat uterus in vitro have been subjected to fractionation according to the method by Free and Wilson which was slightly modified for this purpose. The computation was carried out in several steps. After each step, substances with outlying pA₂ -values were el minated. The reduced group containing 73–79% of the original substances displayed a high degree of additivity of side chain contributions (SCC). This group seems to follow the “participation” rule as formulated by Free and Wilson. Analysis of the group of eliminated substances and of the resulting SCC-spectrum (level diagram) enabled us to draw some conclusions concerning the structural requirements of receptor binding: i) The intact ring structure is necessary for the peptide-receptor interaction: linear peptides or peptides with an extended ring are always outliers; ii) Carba analogues (substitution with CH₂ in the disulfide ring) display better affinities than peptides with an S-S ring; d -Arg⁸ substitution decreases the binding affinity; iii) Considerably better additivity is achieved when peptides are divided into subgroups with vasopressin-like and oxytocin-like features; populations of receptors more specific for vasopressin and for oxytocin, respectively, can be assumed. Estimates of the “true” receptor-peptide dissociation constants can be obtained by summation of the corresponding SCC's in each investigated position. The value obtained for oxytocin is identical with the medium affinity binding site on myometrial cells, and not with the high affinity site. A nonlinear relationship exists between SCC's computed from pA₂-values for magnesium-free and magnesium-containing (0.5 mm ) media but no evidence speaks in favor of a Mg-potentiating effect on receptor binding.