Background: Cancer cell line-derived feeder cells enhance natural killer (NK) cell expansion; however, concerns regarding viable residual feeder cells in the final product limit their use. Evidence supporting the safety of NK-sensitive K562-based feeders, even when irradiated, is scarce. We optimized an NK cell expansion protocol using genetically engineered K562-mbIL-18/-21 (GE-K562) feeder cells and clinical-grade media and confirmed the absence of residual feeder cells. Methods: NK cell expansion efficiency was compared between feeder-free and feederbased systems using CTS NK-Xpander Medium. To achieve optimal NK expansion, various peripheral blood mononuclear cell (PBMC)-to-feeder ratios and re-stimulation frequencies were tested over 21 days. Flow cytometry and BCR::ABL1 quantitative reverse transcription PCR (RT-qPCR) were used to confirm the absence of feeder cells in the final NK cell product. Results: Feeder-based systems showed superior NK cell fold expansion compared with that of feeder-free systems. Among feeder-based conditions, NK cells expanded 5,224-fold at a 2:1 PBMC-to-feeder ratio after 3 weeks, relative to 1,450-fold at a 6:1 ratio (P < 0.05).Re-stimulation on days 7 and 14 further increased expansion up to 261,457-fold. Irradiated feeder cells showed no proliferation and were eliminated within 3–6 days. On day 21, flow cytometry and BCR::ABL1 RT-qPCR results confirmed the absence of residual feeder cells. Conclusions Our optimized NK cell expansion protocol using irradiated GE-K562 feeder cells and clinical-grade media offers a safe and scalable approach to generating large numbers of NK cells, supporting its potential use in clinical immunotherapy applications.

OBJECTIVES: To investigate compliance of hypertension patients using modified Theory of Reasoned Action(TRA). METHODS: The data were collected for 7-12 April 1997, by interviewing 190 hypertension patients in Hwachon, Kangwon-do. The analytical techniques employed include contingency table analysis and logit analysis. RESULTS: 15.1% of patients were unaware of the fact that he/she has hypertension and 11.2% did not know that he/she should take drug. 26.8% of patients took drug continuously, 20.1% had drug intermittently, and 53.1% had never have treatment. In the contingency table analysis, several variables were found to be significantly related to patient compliance. They included variables for attitude towards the consequences of taking drugs, normative beliefs, systolic BP at the enrollment, knowledge of how to take hypertensive drugs, variables for general health behavior and experience with having health worker's home visit. The logit analysis was performed by two steps. First step uses experience with drug treatment of hypertension as the dependent variable, and second step uses continuity of treatment. Included in the predictors that are significantly related to the former analysis are subjected norms produced by combining normative beliefs and motivation to comply, knowledge of how to take hypertensive drugs, and opinion about natural recovery of diseases. The only significant determinant of continuous treatment was knowledge of how to take hypertensive drugs. CONCLUSIONS: The results of analysis suggest the usefulness of TRA as a framework for the study of compliance of hypertensive patients. The findings have some practical implication as well. One is that efforts for enhancing compliance should be directed not only patients but also to other persons influencing patient's attitude and behavior. It also suggest that correct understanding of hypertension treatment is essential to perform the appropriate patient role.
Compliance ; Gangwon-do ; Health Behavior ; House Calls ; Humans ; Hypertension* ; Motivation ; Patient Compliance*

This study examined the effects of referral requirements for insurance patients which have been enforced since July 1, 1989 when medical insurance coverage was extended to the whole population except beneficiaries of medical assistance program. The requirements are mainly aimed at discourag - ing the use of to Vii; ry care hospitals by imposing restrictions on the patient's choice of a medical service facility. The expectation is that such change in the pattern of medical care utilization would produce several desirable effects including increased efficiency in patient care and balanced development of various types of medical service facilities. In this study, these effects were assessed by the change in the number of out-patient visits and bed-days per illness episode and the share of each type of facility in the volume of services and the amount of expenditures after the implementation of the new referral system. The data for analysis were obtained from the claims to the insurance for government and school employees. The sample was drawn from the claims for the patients treated during the first six months of 1989, prior to the enforcement of referral requirements, and those of the patients treated during the first six months of 1990, after the enforcement. The 1989 sample included 299,824 claims (3.6% of total) and the 1990 sample included 332,131(3.7% of total). The data were processed to make the unit of analysis an illness episode instead of an insurance claim. The facilities and types of care utilized for a given illness episode are defined to make up the pathway of medical care uti lization. This pathway was conceived of as a Markov Chain process for further analysis. The conclusion emerged from the analysis is that the enforcement of referral requirements resulted in less use of tertiary care hospitals, and thereby decreased the volume of services and the amount of insurance expenses per illness episode. However, there are a few points that have to be taken into account in relation to the conclusion. The new referral system is likely to increase the use of medical services not covered by insurance, so that its impact on national health expenditures would be different from. that on insurance expenditures. The extension of insurance coverage must have inereased patient load for all types of medical service organizations, and this increase may be partly responsible for producing the effects attributed to the new referral system. For example, excessive patient load for tertiary care hospitals may lead to the transfer of their patients to other types of facilities. Another point is that the data for this study correspond to very early phase of the new system. But both patients and medical care providers would adapt themselves to the new system to avoid or overcome its disadvantages for them, so as that its effects could change over time. Therefore, it is still necessary to closely monitor the impact of the referral requirements.
Health Expenditures ; Humans ; Insurance Coverage ; Insurance* ; Markov Chains ; Medical Assistance ; Outpatients ; Patient Care ; Referral and Consultation* ; Tertiary Healthcare