Effects of Delay in Tumor-Immune System on Stability / 医用生物力学

Objective To study stability of the deterministic tumor-immune system with time delay by means of linear stability analysis method. Methods In tumor-immune system, since it took some time for immune cells to recognize tumor cells and respond appropriately, time delay was considered in this process, then the model was simplified by using Taylor expansion of small delay, and the equilibrium points were solved out. By linear stability analysis method, the stability of these equilibrium points was studied. Finally, the trajectory of the system and that around each equilibrium point were simulated by numerical calculation method, so as to verify the result of theoretical analysis. Results The system had four meaningful equilibrium points with small delay, including a stable focus, a stable node, and two saddles. Moreover, the type and stability of these equilibrium points were not affected by the delay. Numerical simulation demonstrated the conclusion from theoretical analysis. Conclusions Under the condition of small delay, the type and stability of equilibrium points in the system are notaffected by the delay. The results are helpful to further understand dynamic mechanisms of tumor immune response, and provide references for tumor growth and treatment

Practical Optimization and Application of Time-delay Exposure System for Mobile Digital Radiography Equipment / 中国医疗器械杂志

This study introduced a time-delay exposure system independent of the mobile digital radiography equipment. The system consisted of lithium battery, delay control circuit, micro electric motor and related auxiliary facilities. When the starting time was reached through the delay circuit, the motor pushed out the rod to squeeze the exposure button and completed the exposure. The accessories used in this system were easy to purchase and cheap. At the same time, the technology was mature and had good compatibility. The exposure success rate was high and the exposure effect was satisfactory. This time-delay exposure system had good practicability and popularization value.

Variación poblacional de tres especies de piqueros (Suliformes: Sulidae) en isla Gorgona, Pacífico colombiano, según la temperatura del mar

Introducción: La alteración de la temperatura del ambiente pelágico puede repercutir en la variación poblacional de los consumidores tope como las aves marinas. Objetivo: Evaluar la respuesta poblacional de tres especies de piqueros en isla Gorgona (Pacífico colombiano) con respecto a la variabilidad local y regional de las condiciones de temperatura superficial del mar (TSM). Métodos: Se analizaron las tendencias mensuales de la abundancia de Sula leucogaster, Sula nebouxii y Sula variegata en relación a la variación de la TSM en el área de influencia de Gorgona, la región de San José en la costa del Perú y la región Niño 1+2. Resultados: La mayor correlación positiva se presentó entre S. nebouxii y S. variegata con la TSM de la región Niño 1+2, con un desfase de cuatro y cinco meses, respectivamente. Este desfase temporal posiblemente corresponde al tiempo que demora su migración entre la costa peruana y Gorgona. En contraste, la abundancia de S. leucogaster disminuyó al aumentar la TSM mensual de Gorgona. Conclusiones: Es probable que las tendencias descritas estén relacionadas con la disminución de la productividad y disponibilidad de presas asociadas con temperaturas más cálidas en estas áreas. Se sugiere que la TSM puede influir sobre las tendencias de abundancia de los tres piqueros, y su continuo monitoreo permitirá mejorar el conocimiento sobre la variación natural de estas poblaciones.

Introduction: Pelagic environment temperature variations may influence population variation of top predators, such as seabirds. Objective: A population response assessment of three species of boobies, in Gorgona Island (Colombian Pacific), in relation to sea surface temperature (SST) variations. Methods: We assessed the relationship between SST variability and monthly abundance of Brown Boobies, Blue-footed Boobies and Peruvian Boobies, in the influence area of Gorgona, the San José region (Peruvian coast) and the Niño 1+2 region. Results: The largest positive correlation was observed between Blue-footed Boobies and Peruvian Boobies with SST at the Niño 1+2 region, with a lag of four and five months, respectively. This delay may correspond to the migration duration from the Peruvian coast to Gorgona. In contrast, Brown Booby abundance decreased as monthly SST in Gorgona increased. Conclusions: These trends may be related to less productivity and prey availability associated with warmer sea surface temperatures. We suggest that SST influences the abundance trend of these three species, and their continuous monitoring will improve our knowledge on the natural variation of these populations.

Model Simulation of the Resting Tremor Mechanism in Parkinson’s Disease / 医用生物力学

Objective To study the internal relationship between resting tremor and slow response in patients with Parkinson’s disease. Methods The movement characteristics of wrist joints in valgus direction was studied by dynamic modeling on wrist joints of the upper limbs. The system delay concept was introduced with human autonomous control and the sensory delay characteristics of Parkinson’s patients was simulated, to make stability analysis and dynamic response of the involuntary wrist movement. Results The stability analysis and numerical solution of this time-delayed control system showed that when the sensation was delayed to a certain extent, involuntary tremor of wrist joints in patients with Parkinson’s disease would happen, which conformed to resting tremor from Parkinson’s disease. Conclusions Resting tremor from Parkinson’s disease is caused by sensation and movement delay.

Evaluation of Bispectral Index time delay in response to anesthesia induction: an observational study / Avaliação do tempo de atraso do índice bispectral na resposta à indução da anestesia: estudo observacional

Abstract Background and objectives According to the manufacturer, the Bispectral Index (BIS) has a processing time delay of 5-10 s. Studies addressing this have suggested longer delays. We evaluated the time delay in the Bispectral Index response. Methods Based on clinical data from 45 patients, using the difference between the predicted and the real BIS, calculated during a fixed 3 minutes period after the moment the Bispectral Index dropped below 80 during the induction of general anesthesia with propofol and remifentanil. Results The difference between the predicted and the real BIS was in average 30.09 ± 18.73 s. Conclusion Our results may be another indication that the delay in BIS processing may be much longer than stated by the manufacture, a fact with clinical implications.

Resumo Justificativa e objetivos De acordo com o fabricante, o índice bispectral (BIS) tem um tempo de processamento de cinco a dez segundos. Estudos que avaliaram esse tempo de processamento sugeriram atrasos mais longos. Nós avaliamos o tempo de atraso na resposta do BIS. Métodos Com base em dados clínicos de 45 pacientes, calculamos a diferença entre o tempo de atraso previsto e real do índice bispectral durante um período fixo de três minutos após o momento em que o BIS caiu abaixo de 80 durante a indução da anestesia geral com propofol e remifentanil. Resultados A diferença entre o BIS previsto e real foi em média 30,09 ± 18,73 segundos. Conclusão Nossos resultados sugerem que o atraso no processamento do índice bispectral pode ser muito maior do que o declarado pelo fabricante, um fato com implicações clínicas.

Practices causing time delay in seeking care for mental illness

Background: Mental health is the foundation for wellbeing and effective functioning for an individual. When people consult clinicians to determine the cause and treatment for such illness, they may also seek answers to questions that medical science can’t answer. Many patients rely on a religious or traditional framework to help answer these questions that often hinder medical treatment and affect its prognosis. This study aim to estimate the practices adopted by the community for cure of mental illness and estimates the time delay that occurred to initiate medical treatment because of these practices.Methods: A cross sectional study was conducted among 103 patients and their caretakers undergoing treatment in the Psychiatry Department of a tertiary care hospital using a semi structured questionnaire. The data collected was analyzed for mean and statistical significance between proportions.Results: Among the 103 patients, 54.4% were males and 45.6% females. 54.3% of patients suffered from psychosis and 45.6% from neurotic illness. About 60.1% of the patients had experienced some form of traditional and religious practices for treating their illness before approaching medical treatment causing an average time delay of 2.6 years to initiate regular medical treatment.Conclusions: The high rate of religious and traditional practices followed by the community for psychiatric illness leads to significant time delay in initiating evidence based management of illness resulting in significant reduction in the quality of life of these patients. Hence mental health awareness initiative at community level and strengthening mental health services at primary care level is the need of the hour.

Reducing Preoperative Waiting-time in a Pediatric Eye Operation Theater by Optimizing Process Flow: A Pilot Quality Improvement Project

Objective: To decrease the preoperative area waiting-time forchildren posted for eye surgery.Methods: A pilot quality improvement project was conducted in asingle paediatric eye operation theatre in our tertiary-carehospital. Operation theatre process flow was analyzed, baselinedata was collected, and two Plan-Do-Study-Act cycles wereperformed on consecutive days. Average and maximal waiting-time were recorded across six operation theatre days.Results: The average and maximal waiting time at baseline were221 and 390 minutes, respectively. After two rapid Plan-Do-Study-Act cycles, these were reduced to 29 (87% reduction) and 52minutes (87% reduction) from baseline, respectively, and couldsubsequently be sustained.Conclusion: Preoperative waiting time in ophthalmic operationtheatre was significantly reduced by simple process flowoptimization, thereby improving quality of care.

The effect of time delay on tumor-immune system in tumor growth / 医用生物力学

Objective To study the effect of time delay on tumor-immune system in tumor growth through theoretical approaches. Methods A mathematical model of the tumor-immune system interactions was established, and a time delay in the logistic growth term was introduced to investigate the processes of the interaction between immune system and tumor cells through qualitative analysis and numerical simulations. The relationship between the states of tumor and time delay was analyzed and the results were compared with the stages of the cancer immunoediting. Results Qualitative analysis and numerical simulations indicated that the tumor-immune system was a stable equilibrium state if the time delay was small. With the time delay increasing, the tumor-immune system entered equilibrium and escape stages of the cancer immunoediting, which described the alteration from dormant state to malignant state. Conclusions The time delay plays a key role in the interaction between immune system and tumor cells. The different time delays can result in different behaviors of tumor. The results will help to deepen clinical understanding of the tumor-immune system and provide references for the analysis and treatment of tumor.

An experiment set-up for analysis of lateralization judgments of binaural stimuli

INTRODUCTION: The aim of this work is to present a physical implementation of a noninvasive methodology to analyze the directional sensitivity of human auditory system. A computer controlled experiment set-up has been designed and developed to study the behavior of human subjects under the presentation of interaural time delays and interaural amplitude differences for several sensation levels. METHODS: The proposed methodology comprises: the application of trains of low-pass filtered narrow pulses as acoustic binaural stimuli; the automatic, simultaneous and random variation of interaural time delays and interaural amplitude differences; the absence of human interference along the experimental sessions, except for the decision of the listener under test; the minimization of adaptation effects. RESULTS: Numerous lateralization judgments have been accomplished in order to investigate the transduction mechanism which allows deciding which side of subjects medial plane the source of binaural acoustic stimuli is located in. The behavior of decision time with the order of judgment, the sensation levels and the interaural differences in time and amplitudes has been analyzed. CONCLUSION: The noninvasive, reliable and automatic approach here presented allows obtaining psychophysical responses associated to the neuro-physiological phenomena underneath lateralization capability.

Regional Cardiocerebrovascular Center Project in the Treatment of Acute Myocardial Infarction / 대한내과학회지

The mortality of cardiac and cerebro-vascular disease has been increased in Korea rapidly. Regional cardiocerebrovascular center project was begun to decrease of the mortality of these disease on 2008. Acute myocardial infarction (AMI) and stroke are the targets of this project. The time delay from the onset to visiting hospital is one of the interrupting steps from the early reperfusion therapy in the patients with acute ST-segment elevation myocardial infarction (STEMI). Regional Cardiac Center project showed shortened door to balloon time in patient with STEMI undergoing primary PCI. Regional Cardiac Center project supports the media campaign about STEMI symptoms, early visit to emergency department, use of ambulance, and patient education. Good cooperation between regional emergency centers and regional cardiovascular center will improves survival of sudden cardiac collapse. These all activity will shorten time delay in treatment of AMI, reduce mortality rate and medical cost in the future.

Analysis of Time Delay to Affect Thrombolytic Therapy in Patients with Acute Myocardial Infarction

BACKGROUND: Early reperfusion therapy with thrombolytic agents or primary PTCA is most important to salvage ischemic myocardium in acute myocardial infarction(AMI). Timely reperfusion of jeopardized myocardium clearly improves hemodynamics, decreases infarct size and improves survival. The extent of protection appears to be directly related to the rapidity of reperfusion after onset of coronary occlusion. Although the intravenous thrombolysis is a feasible therapy in the patients with evolving AMI, the benifit of thrombolytic therapy decreases because of the time delay after onset of symptom. This study was perfomed to analyze the factors time delay between onset of symptom and the thrombolytic therapy with retrospective and prospective questionaire in the patients with AMI. METHOD: Eighty one patients with AMI were included in this study who came to the emergency room(ER) of Chungnam National University Hospital(CNUH) from Feburary 1995 to October 1996. Delay between door and thrombolytic therapy was defined as hospital time delay. RESULTS: Thrombolytic therapy(rt-PA or urokinase iv) was done in 60 patients(74.1%) and mean prehopital time delay was significantly decreased in the patients with thrombolytic therpapy when compared with those without thormbolytic threapy(462+/-90 vs 1375+/-473 minutes, p=0.005). There were no singificant factors for prehospital time delay such as age, sex, redsidence, ER near residence, transfer time to ER near residence, family status, family history of AMI, severity of chest pain, presence of risk factors of cardiovascular disease(CVD), previous CVD, degree of education, history of other disease and routine check, transfer methods. The only 8 patients(9.8%) knew about AMI and 7 patients among these patient came to ER earlier and received thrombolytic therapy. From 57 referred patients, 40 patients(70.2%) received reperfusion therapy and only 30 patients(52.6%) had recored EKG in the referred hospital. In the analysis of hospital delay from patient's arrival to the thrombolytic therapy, the arrival time at weekdays and weekend had no differences, but hospital delay were significantly prolonged when patients arrived at ER in the night. CONCLUSION: Since prehospital time delay is a most important factor of time delay for the effective thrombolytic therapy in AMI, the pubic education program and effective transport system are needed. And routine record of EKG in patient with chest pain in the local hospital is very helpful to start effective thromolytic therapy at ER. The well designed prospective study with more patinets in our local region is essential to get more accurate information about transport system and to improve survival rate in patients with AMI.

The cooperation of NO air-feed system and respirator / 医疗卫生装备

The cooperation of NO air-feed system and respirator, in which the integrative and separate modes are involved, is introduced in this paper. Its disadvantages and development trend are also discussed on the bases of the constitution of the mixed gas containing NO and O2/air, the synchronous working of NO air-feed system and respirator and the inspection of NO/NO2 gas.

Traumatic Intracerebral Hematoma

During a 36-month period, clinical outcome in 170 patients with traumatic intracerebral hematoma(TICH) was analysed. These patients represented 5.1% of 3328 consecutive patients with head injuries admitted to the Soonchunhyang University Chunan Hospital. The overall mortality was 33.5%. A significant number of patients(52.6%), who were not comators at the time of admission(GCS0.005) ; 2) the presence of associated lesions(p>0.01) ; 3) time delay of two hours or more from admission to operation(p>0.05) ; 4) actual midline shift of 4.5mm or above on initial CT scan(p>0.005) ; 5) obliteration of suprasellar cistern(p>0.005) ; 6) the presence of delayed traumatic intracerebral hematoma(DTICH) in non-surgical patients with GCS score of 8 or above(p>0.01). Age and location of hematoma did not affect outcome, but the patients with multiple located hematoma showed higher mortality than the others. Time delay in the treatment of TICH and DTICH contribute significantly to poor outocme. Rapidly progressive DTICH within 48 hours after trauma is high in mortality. Follow-up CT scan might as well be performed till 48 hours after injury and 8 hours after initial operation, even though neurological status did not alter for the worse.