FURTHER STUDIES OF THE STIMULATION OF DNA SYNTHESIS IN CULTURES OF SPLEEN CELL SUSPENSIONS BY HOMOLOGOUS CELLS IN INBRED STRAINS OF MICE AND RATS

The early proliferative response previously demonstrated in rabbits has now been shown to follow the mixing of spleen cell suspensions from 2 inbred strains of mice or rats. The size of the response is comparable to that seen in cells from hyperimmune animals exposed to antigen in vitro. Autoradiographs of cells from stimulated cultures showed 1 to 4 per cent of the total population had incorporated thymidine. Modifications in the conditions necessary for the culture of mice and rat spleen cell suspensions and the measurement of thymidine incorporation are described. No responses were observed in isologous mixes. The responses obtained on mixing individual pairs of spleens from different strains showed relatively little variation. Responses were obtained in all of the 21 possible combinations between 7 inbred strains of mice. Responses were obtained when parental cells were mixed with their F1 hybrids. Analysis of these responses showed that, in every case, parental-F1 hybrid responses were less intense than those between the 2 parents. It was shown that there was no inherent defect in the ability of the hybrid cells to respond when mixed with an unrelated strain. The results suggested that the hybrid cells made no response to the parent cells although this was not conclusively established. This has been taken as circumstantial evidence that the response is immunological in nature. The significance of the vigor of the response and the large fraction of the immunologically competent cells that take part is discussed

Factor VII and the brain: time to get this research done!

Traumatic brain injury is the leading killer after trauma, in part because of coagulopathy. Factor VIIa may be a useful therapy in this setting, depending on the relative risk for thromboembolic complications. Kluger and coworkers recently conducted a retrospective review of patients with traumatic brain injury from a previous factor VIIa and trauma trial. It documents an encouragingly low rate of complications, and should provide a strong incentive to conduct a prospective study of factor VIIa in patients with severe traumatic brain injury

SPLEEN CELL PROLIFERATION IN RESPONSE TO HOMOLOGOUS ANTIGENS STUDIED IN CONGENIC RESISTANT STRAINS OF MICE

The proliferative responses obtained when spleen cell suspensions from two different inbred strains of mice were mixed were investigated further using congenic resistant strain pairs. Strong responses were obtained in 9 cases out of 12 where the two strains differed at a single gene locus controlling an H-2 histocompatibility antigen. No responses were obtained where the difference occurred at loci controlling weak histocompatibility antigens. These findings have been taken to provide additional circumstantial evidence that the response represents an in vitro homograft reaction to homologous tissue antigens

Polynomial system identification modeling and adaptive model predictive control of arterial oxygen saturation in premature infants

The automation of the regulation of the fraction of inspired oxygen (FiO2) in neonatal mechanical ventilation to treat respiratory distress syndrome has proven challenging due to competing objectives: maintaining arterial oxygen saturation levels (SpO2) while simultaneously not inducing complications such as retrolental fibroplasia. Historically, models of the dynamics of the neonatal respiratory system were first order transfer function approximations. This work used higher order polynomial system identification methods with the model structures of autoregressive with exogenous inputs (ARX) and Box-Jenkins (BJ) models to investigate possible improved modeling of the dynamic relationship between the FiO2, Heart Rate (HR), and Respiratory Rate (RR) to the SpO2. Through a parameter sweep of different of polynomial orders and sampling delays, 3,456 ARX models and 13,176 BJ models were created, with four being selected for comparison based upon modeling performance metrics. From these best performing models, it was concluded that the FiO2 relationship to SpO2 could still be adequately approximated by a first order transfer function model with delay. The disturbance HR, RR, and the unmodeled dynamics did require higher order approximations. It was also shown that selecting a model based off the Akaike's Information Criterion was preferred in picking a model from a collection of identified models. With a singular winning model from the four best performing models, an adaptive model predictive controller (AMPC) was designed to adhere to clinical best practices to regulate the SpO2. Through a recursive polynomial model estimator (RPME), an ARX approximation of the unknown model's dynamics for the FiO2, HR, and RR relationship to the SpO2 could be used to update the internal model of the AMPC. Through this online model estimation, the AMPC could successfully feedforward reject the HR and RR disturbances improving the simulated time within the SpO2 target limits, 67.8% of simulation time, to a baseline PI controller's 56.6%, in periodic desaturation simulations.Includes bibliographical references (pages 63-65)

Analysis of existing mathematics textbooks for use in secondary schools.

Thesis (Ed.M.)--Boston University Thesis (M.A.)--Boston Universit