The influence of mixed hematopoietic chimerism (MC) after allogeneic bone marrow transplantation remains unknown. Increasingly sensitive detection methods have shown that MC occurs frequently. We report a highly sensitive novel method to assess MC based on the polymerase chain reaction (PCR). Simple dinucleotide repeat sequences called microsatellites have been found to vary in their repeat number between individuals. We use this variation to type donor-recipient pairs following allogeneic BMT. A panel of seven microsatellites was used to distinguish between donor and recipient cells of 32 transplants. Informative microsatellites were subsequently used to assess MC after BMT in this group of patients. Seventeen of the 32 transplants involved a donor of opposite sex; hence, cytogenetics and Y chromosome-specific PCR were also used as an index of chimerism in these patients. MC was detected in bone marrow aspirates and peripheral blood in 18 of 32 patients (56%) by PCR. In several cases, only stored slide material was available for analysis but PCR of microsatellites or Y chromosomal material could be used successfully to assess the origin of cells in this archival material. Cytogenetic analysis was possible in 17 patients and MC was detected in three patients. Twelve patients received T-cell-depleted marrow and showed a high incidence of MC as revealed by PCR (greater than 80%). Twenty patients received unmanipulated marrow, and while the incidence of MC was lower (44%), this was a high percentage when compared with other studies. Once MC was detected, the percentages of recipient cells tended to increase. However, in patients exhibiting MC who subsequently relapsed, this increase was relatively sudden. The overall level of recipient cells in the group of MC patients who subsequently relapsed was higher than in those who exhibited stable MC. Thus, while the occurrence of MC was not indicative of a poor prognosis per se, sudden increases in the proportions of recipient cells may be a prelude to graft rejection or relapse.

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The design of CFA piles in the stiff/hard lodgement till that underlies most of Dublin is usually based on published experience from similar piles in other soils that lack the high density and stiffness of this till. The results of load tests on two instrumented test piles are presented, one 450 mm in diameter and 12·3 m long and the other 600 mm in diameter and 11 m long, which were loaded to 3·15 MN and 4·5 MN respectively. A 1 m long instrumented dummy pile was formed at the same time as the prototype and was tested in the laboratory to confirm the calibrations for use in interpreting the instrumentation. The instrumented piles showed that high average shaft resistances of 230 kPa and 270 kPa were mobilised, which were of similar magnitude to those recorded on an instrumented driven pile in this lodgement till that was reported previously. The pile load tests indicate an estimated Nc value of about 7 for the bearing capacity factor in ultimate end resistance, which is less than the value of 9 normally used and considerably less than a value of about 55 estimated from the tests on the driven pile. The results also indicate a change in the load–pile-head deflection curves with time, which could be related to disturbance of the ground caused by the construction process.

The use of the finite element method to model excavations and tunnels in Dublin black boulder clay has, in the past, had limited success owing to the failure of the available constitutive models in commercially available software programs to adequately represent the essential features of a stiff soil. A stiff soil — lodgement till — underlies much of the city of Dublin, Ireland; consequently, the successful prediction of deformations in this soil arising from structural and infrastructural projects is of considerable importance. Research has shown that the stress–strain response of a stiff soil is complex and depends on many factors including stress history, stress level, and strain direction. These important features are included in the hardening plasticity small strain stiffness (HSS) soil model that is incorporated in the Plaxis V8.4 finite element code. This paper describes the field and laboratory methods that were used to determine the parameters for incorporation in this soil model and the validation of these parameters. These parameters are used to model the deformations around two excavations: a 4.5 m deep excavation with a vertical face, and a 10.7 m deep excavation with a face slope of 70°–75°. Good agreement was found between the predicted and observed deformations.