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At least 433 records · Page 24Linked to original sources
PubMed2006

Is there a need to optimize glycemic control in hemodialyzed diabetic patients?

The report of Williams et al. gives rise to at least two important questions regarding diabetic patients on maintenance hemodialysis: (1) Does glycemic control play a significant role? (2) Is HbA1c a reliable measure of glycemic control? These questions are discussed. It is recommended that you treat ESRD patients with diabetes according to guidelines given for patients without ESRD.

Blood Glucose↗
PubMed1999

Optimal chaos control through reinforcement learning.

A general purpose chaos control algorithm based on reinforcement learning is introduced and applied to the stabilization of unstable periodic orbits in various chaotic systems and to the targeting problem. The algorithm does not require any information about the dynamical system nor about the location of periodic orbits. Numerical tests demonstrate good and fast performance under noisy and nonstationary conditions. (c) 1999 American Institute of Physics.

Journal Article↗
PubMed2000

Simulation of the Seated Postural Stability of Healthy and Spinal Cord-Injured Subjects Using Optimal Feedback Control Methods.

A two-dimensional, biomechanical computer model was developed, using the software package Working Model(TM), to simulate the postural control of seated individuals. Both able-bodied and spinal cord-injured subjects were represented. The model incorporated active control of the upper body through full-state feedback. Specifically, a linear quadratic regulator scheme was implemented in the model. Nonlinearities were included in the torque computations to mimic physiological constraints and disability. Interactions between the subject and the wheelchair were also included in the model. Simulation results were compared with those obtained from experiments in which the subjects had attempted to remain stable during the application of significant disturbance moments, similar to those experienced during braking in a vehicle. While subjects exhibited more complex control schemes, the model was able to simulate overall stability. Therefore, it is believed that the model could prove beneficial to future research examining the effects of various restraints on stability.

Journal Article↗
PubMed1989

Clinically useful limits (CUL) criteria as a basis for quality control including minimal and optimal goals for quality control.

Quality control goals for quantitative clinical chemistry assays are reviewed. Recommendations for clinically useful limits (CUL) criteria as minimally acceptable +/- 2 SD for run-to-run and/or day-to-day technical reliability are presented in terms of biologic variations for different levels and clinical applications. A review of the literature and the questionnaire response of a medical school staff presented in this study reveal striking agreement of acceptable analytic goals based on physicians' opinions, biologic variation, and practical analytic feasibility. The current state-of-the-art in clinical laboratories can approach excellence because actual within-laboratory 2-SD variability estimates are somewhere between acceptable CUL criteria and twice as good. Assessing the reliability of laboratory reports based on accuracy and precision or total analytic error is also discussed.

Blood Chemical Analysis↗
PubMed1999

Factors influencing the optimal control-to-case ratio in matched case-control studies.

Statistical power in matched case-control studies depends on both the correlation coefficient between cases and their matched controls (phi) and the prevalence of exposure among controls (P0). To examine the hypothesis that the value of increasing the control-to-case ratio beyond 5 varies with both phi and P0, the authors estimated statistical power for a hypothetical case-control study under different assumptions. The effect of increasing the control-to-case ratio depended on phi and, to a lesser extent, on P0. The results suggest that investigators consider including more than five controls per case when either phi is greater than about 0.2 or P, is less than about 0.15.

Bias↗
PubMed1999

Synchronizing chaos in an experimental chaotic pendulum using methods from linear control theory.

Linear feedback control, specifically model predictive control (MPC), was used successfully to synchronize an experimental chaotic pendulum both on unstable periodic and aperiodic orbits. MPC enables tuning of the controller to give an optimal controller performance. That is, both the fluctuations around the target trajectory and the necessary control actions are minimized using a least-squares solution of the linearized problem. It is thus shown that linear control methods can be applied to experimental chaotic systems, as long as an adequate model is available that can be linearized along the desired trajectory. This model is used as an observer, i.e., it is synchronized with the experimental pendulum to estimate the state of the experimental pendulum. In contrast with other chaos control procedures like the map-based Ott, Grebogi, and York method [Phys. Rev. Lett. 64, 1196 (1990)], the continuous type feedback control proposed by Pyragas [Phys. Lett. A 170, 421 (1992)], or the feedback control method recently proposed by Brown and Rulkov [Chaos 7 (3), 395 (1997)], the procedure outlined in this paper automatically results in a choice for the feedback gains that gives optimum performance, i.e., minimum fluctuations around the desired trajectory using minimum control actions.

Journal Article↗
PubMed2004

Post-herpetic neuralgia case study: optimizing pain control.

Post-herpetic neuralgia (PHN) is a chronic pain syndrome associated with the reactivation of a primary infection with varicella zoster virus (chicken pox), which leads to a chronic infection of the dorsal root ganglia. Under various clinical circumstances, including immunosuppressive diseases or treatments and certain cancers, reactivation of the infection can occur in adults as shingles. Other factors such as psychological distress and stressful life events also appear to play a role in the onset of shingles and the development of PHN. The most common risk factor for shingles and its potential sequela, PHN, is advanced age. For a significant number of patients, the pain following healing of shingles can persist for months to years; this pain is classified as PHN if it persists longer than 3 months. PHN often leads to depression, disrupted sleep, decreased functioning and increased healthcare utilization. Prompt use of antiviral therapy appears to reduce the period of pain following an episode of shingles by about half and may possibly reduce the overall incidence of PHN. Damage to a variety of neurologic pathways as a result of herpes zoster reactivation suggests that intervention with multiple agents having divergent mechanisms of action is an appropriate treatment approach. Current treatment options aimed at relieving the symptoms of PHN include antidepressants, opioids, anticonvulsants and topical analgesics. It is important for the clinician to establish a baseline pain intensity and character as well as quality of life measures against which to judge the effectiveness of any treatment. This review article features a case study of a patient with PHN to illustrate current diagnostic and treatment approaches.

Acetates↗
PubMed2004

Optimal impedance control for task achievement in the presence of signal-dependent noise.

There is an infinity of impedance parameter values, and thus different co-contraction levels, that can produce similar movement kinematics from which the CNS must select one. Although signal-dependent noise (SDN) predicts larger motor-command variability during higher co-contraction, the relationship between impedance and task performance is not theoretically obvious and thus was examined here. Subjects made goal-directed, single-joint elbow movements to either move naturally to different target sizes or voluntarily co-contract at different levels. Stiffness was estimated as the weighted summation of rectified EMG signals through the index of muscle co-contraction around the joint (IMCJ) proposed previously. When subjects made movements to targets of different sizes, IMCJ increased with the accuracy requirements, leading to reduced endpoint deviations. Therefore without the need for great accuracy, subjects accepted worse performance with lower co-contraction. When subjects were asked to increase co-contraction, the variability of EMG and torque both increased, suggesting that noise in the neuromotor command increased with muscle activation. In contrast, the final positional error was smallest for the highest IMCJ level. Although co-contraction increases the motor-command noise, the effect of this noise on the task performance is reduced. Subjects were able to regulate their impedance and control endpoint variance as the task requirements changed, and they did not voluntarily select the high impedance that generated the minimum endpoint error. These data contradict predictions of the SDN-based theory, which postulates minimization of only endpoint variance and thus require its revision.

Adult↗
PubMedDate not supplied

Physiologic insulin replacement in type 2 diabetes: optimizing postprandial glucose control.

PURPOSE: The purpose of this article is to review physiologic insulin replacement using a basal-prandial approach and focus on the role of postprandial glucose control. In addition, therapeutic options for optimizing glycemic control are described, including diabetes education, currently available agents, treatment regimens, and strategies. METHODS: This article reviews the benefits of treating with a basal-prandial insulin approach and focuses on post-prandial glucose-targeted therapies, including rapid-acting insulin analogs. RESULTS: Data from landmark clinical trials in type 2 diabetes suggest that intensive glycemic control can reduce the frequency and severity of diabetes complications. A basal-prandial insulin regimen combines a long-acting insulin analog with a rapid-acting insulin to mimic normal physiologic insulin secretion, providing a flexible tool to enhance patient self-management. CONCLUSIONS: Strategies that include patient education, improved health care provider/patient communication, and basal-prandial insulin treatment can help patients achieve good glycemic control. The optimal setting for successful diabetes treatment is a team approach with the health care provider, nurse/certified diabetes educator, and patient as essential members.

Blood Glucose↗
PubMed2004

Fine-tuning therapy with basal insulin for optimal glycemic control in type 2 diabetes: a review.

OBJECTIVE: To review results from clinical studies utilizing basal insulin therapy and discuss the impact of intensive glycemic control using forced-titration algorithms to fine-tune insulin dosing in patients with type 2 diabetes mellitus. RESEARCH DESIGN AND METHODS: A Medline and PubMed search was undertaken for the years 1991-2004 using the following search terms: insulin, diabetes therapy, forced titration, glycemic control, and intensive insulin therapy. RESULTS: The United Kingdom Prospective Diabetes Study demonstrated that the great majority of patients with type 2 diabetes will eventually require insulin and have provided level IA evidence that intensive glycemic control improves patient outcomes. Several recently published studies in patients with type 2 diabetes showed that forced titration of basal insulin shows promise in reaching glycemic goals. Forced-titration algorithms employ a structured approach in helping patients achieve glycemic targets: doses are adjusted until glycemic goals (predefined glycosylated hemoglobin concentrations and/or blood glucose levels) are met. CONCLUSION: Studies have indicated that forced-titration regimens using insulin analogs to attain aggressive glycemic targets have the potential to improve outcomes in patients with type 2 diabetes without compromising patient safety. These forced-titration algorithms are straightforward and designed to be adaptable to individual needs, which may help overcome barriers to insulinization of patients with type 2 diabetes.

Blood Glucose↗