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 51,768 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The control of a cyclical movement of the lower leg with electrical stimulation of the quadriceps muscles is formulated as an optimal control problem. The time integral of knee torque is taken as the optimisation criterion. As an additional condition, every cycle a certain reference maximum angle should be reached. A model study indicates that one stimulation burst per cycle at the maximum recruitment level is a suboptimal solution to this problem. To compensate for the influence of muscle fatigue, the burst time is adaptively adjusted by a discrete time PID-controller on the basis of the performance in the previous cycles. This strategy appeared to be successful in experimental tests. A considerable time difference (about 0.15 s) was found between the end of the stimulation burst and the tracking of the passive state trajectory, which satisfies the maximum angle condition.
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PMID:Control of FES-induced cyclical movements of the lower leg. 181 49

The clinicopathological and immunohistochemical findings in 25 cases of inflammatory pseudotumor of lymph nodes (IPT) are presented. The patients were 13 women and 12 men between 8 and 81 years of age. Clinically, symptoms of prior infection, fatigue, abdominal pain, weight loss, fever of unknown origin, pelvic inflammatory disease, or nausea and night sweats were obtained in 15 patients, whereas six patients presented with asymptomatic lymphadenopathy. In four additional patients, no clinical information was obtained. The involved nodes included cervical, supraclavicular, inguinal, mesenteric, and mediastinal lymph nodes. In two cases, there was synchronous involvement of separate lymph node groups (inguinal and cervical in one case and cervical and mediastinal in another case), whereas in a third patient there was synchronous involvement of the spleen and a paraaortic lymph node. Histologically, the lesions were characterized by a fibrosing/inflammatory process that showed marked heterogeneity and striking variation from case to case. Based on their histological features, the lesions could be classified into three different groups: Stage I was characterized by the appearance of single or multiple small foci containing a spindle cell proliferation admixed with a prominent inflammatory background, with complete preservation of the remainder of the nodal architecture; stage II was characterized by more diffuse involvement of the lymph node with a marked inflammatory response admixed with a prominent myofibroblastic proliferation leading to subtotal effacement of the nodal architecture, often with extension of the process beyond the capsule into perinodal fat; and stage III was characterized by almost complete replacement of the lymph node by diffuse sclerosis with scant residual inflammatory elements and total loss of the normal nodal architecture. Immunohistochemical studies in 20 cases showed a striking number of vimentin- and actin-positive myofibroblastic cells with moderate increase in CD20/CD45+ small lymphocytes and polyclonal plasma cells in the stage I lesions, the emergence of numerous CD68+ histiocytes admixed with lymphocytes, plasma cells, and abundant fibromyofibroblastic cells in the stage II lesions, and only few remaining scattered CD68+ histiocytes and fibroblasts in the stage III lesions. Our findings suggest that inflammatory pseudotumor of lymph node represents an evolving, dynamic process that may adopt different morphological appearances depending on its stage of evolution. Recognition of the various stages of this process may be of importance for differential diagnosis with other fibrosing/inflammatory conditions of lymph nodes.
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PMID:Inflammatory pseudotumor of lymph nodes: a study of 25 cases with emphasis on morphological heterogeneity. 904 98

Progestins in oral contraceptives (OCs) produce potential complications, as well as noncontraceptive benefits, according to Robert A. Hatcher, MD, MPH, professor of gynecology and obstetrics, Emory University Medical School. Hatcher told CTU that lowering the progestin content in an OC may decrease complications, but could also decrease the benefits experienced by women. "The extent to which that will happen remains to be seen," he said. Hatcher cited the following potential complications of progestins in OC: hypertension; decreased levels of high density lipoproteins; acne; oily skin; headaches between pill cycles; dilated leg veins; pelvic congestion syndrome; thrombosis of superficial leg veins; gallstones; Monilia vaginitis; cholestatic jaundice; and depression, fatigue, and decreased libido. Progestins, according to Hatcher, also produce these noncontraceptive benefits: protection against PID; decreased dysmenorrhea; decreased menstrual blood loss, decreased iron deficiency anemia; protection against endometrial cancer; protection against fibrocystic breast disease, and fibroadenomas of the breast; decreased bleeding from fibroids; decreased growth of fibroids. When ovulation is suppressed, Hatcher emphasized, additional benefits that may occur include the following: decreased risk of functional ovarian cysts; elimination of mittleschmerz pain; decreased rick of ovarian cancer; protection against endometriosis.
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PMID:Potential risks, benefits of progestins in birth control pills outlined. 1231 83

Since the last in a series of childbirth education classes discusses contraception, educators must know about various family planning methods. Oral contraceptives (OCs) comprise combined OCs, phasic OCs, and minipills. Combined OCs inhibit secretion of gonadotropin-releasing hormone, which in turn keeps the follicle-stimulating hormone from inducing the ovarian follicle to grow and keeps luteinizing hormones from activating ovulation. They also thicken cervical mucus. Minipills also thicken cervical mucus and render the endometrium unreceptive to fertilized egg implantation. They do not always inhibit ovulation, however. OCs can induce side effects, such as nausea, hypertension, increased risk of atherosclerosis, and fatigue. The IUD prevents pregnancy either by inhibiting implantation of a fertilized egg or by an inflammatory reaction of the endometrium resulting in a release of macrophages which may destroy sperm. The no-longer-produced Dalkon Shield IUD increased the risk of pelvic inflammatory disease and damaged the reputation of other IUDs. Rare IUD complications are uterine perforation, salpingitis, tubal scarring, pelvic inflammatory disease, and infertility. Diaphragms, cervical film, and condoms serve as barriers between the egg and sperm. The main problem with barrier methods is the increased risk of developing toxic shock syndrome. Spermicide increase the effectiveness of diaphragms, cervical caps, and condoms. Vasectomy keeps sperm from arriving at storage sites. Shortterm side effects are swelling, discomfort, and occasional rejoining of the cut ends of the vas. Research hints at a link between vasectomy and prostate cancer. Some complications of tubal ligation are urinary tract infections, accidental electrical burns, and pelvic infections. Natural family planning methods include withdrawal, the rhythm method, and the sypto-thermal method. Controversial injectable contraceptives are Depo-Provera (medroxyprogesterone acetate) and Noristerate (norethisterone enanthate).
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PMID:Birth control update for childbirth educators. 1234 29

Nutrient sensors that can be located directly in the activated sludge processes are gaining in number at wastewater treatment plants. The in situ location of the sensors means that they can be located close to the processes that they aim to control and hence are perfectly suited for automatic process control. Compared to the location of automatic analysers in the effluent from the sedimentation reactors the in situ location means a large reduction in the response time. The settlers typically work as a first-order delay on the signal with a retention time in the range of 4-12 hours depending on the size of the settlers. Automatic process control of the nitrogen and phosphorus removal processes means that considerable improvements in the performance of aeration, internal recirculation, carbon dosage and phosphate precipitation dosage can be reached by using a simple control structure as well as simple PID controllers. The performance improvements can be seen in decreased energy and chemicals consumption and less variation in effluent concentrations of ammonium, total nitrogen and phosphate. Simple control schemes are demonstrated for the pre-denitrification and the post precipitation system by means of full-scale plant experiments and model simulations.
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PMID:Improved nutrient removal using in situ continuous on-line sensors with short response time. 1292 25

A functional electrical stimulation controller is presented that uses a combination of feedforward and feedback for arm control in high-level injury. The feedforward controller generates the muscle activations nominally required for desired movements, and the feedback controller corrects for errors caused by muscle fatigue and external disturbances. The feedforward controller is an artificial neural network (ANN) which approximates the inverse dynamics of the arm. The feedback loop includes a PID controller in series with a second ANN representing the nonlinear properties and biomechanical interactions of muscles and joints. The controller was designed and tested using a two-joint musculoskeletal model of the arm that includes four mono-articular and two bi-articular muscles. Its performance during goal-oriented movements of varying amplitudes and durations showed a tracking error of less than 4 degrees in ideal conditions, and less than 10 degrees even in the case of considerable fatigue and external disturbances.
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PMID:Combined feedforward and feedback control of a redundant, nonlinear, dynamic musculoskeletal system. 1934 88

Osteosarcoma is the most common malignant bone tumor found in children and adolescents and is associated with many complications including cancer pain and metastasis. While cancer patients often seek complementary and alternative medicine (CAM) approaches to treat cancer pain and fatigue or the side effects of chemotherapy and treatment, there is little known about the effect of acupuncture treatment on tumor growth and metastasis. Here we evaluate the effects of six different electroacupuncture (EA) regimens on osteosarcoma tumor growth and metastasis in both male and female mice. The most significant positive effects were observed when EA was applied to the ST-36 acupoint twice weekly (EA-2X/3) beginning at postimplantation day 3 (PID 3). Twice weekly treatment produced robust reductions in tumor growth. Conversely, when EA was applied twice weekly (EA-2X/7), starting at PID 7, there was a significant increase in tumor growth. We further demonstrate that EA-2X/3 treatment elicits significant reductions in tumor lymphatics, vasculature, and innervation. Lastly, EA-2X/3 treatment produced a marked reduction in pulmonary metastasis, thus providing evidence for EA's potential antimetastatic capabilities. Collectively, EA-2X/3 treatment was found to reduce both bone tumor growth and lung metastasis, which may be mediated in part through reductions in tumor-associated vasculature, lymphatics, and innervation.
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PMID:The effect of electroacupuncture on osteosarcoma tumor growth and metastasis: analysis of different treatment regimens. 2422 59

Robotic and functional electrical stimulation (FES) approaches are used for rehabilitation of walking impairment of spinal cord injured individuals. Although devices are commercially available, there are still issues that remain to be solved. Control of hybrid exoskeletons aims at blending robotic exoskeletons and electrical stimulation to overcome the drawbacks of each approach while preserving their advantages. Hybrid actuation and control have a considerable potential for walking rehabilitation but there is a need of novel control strategies of hybrid systems that adequately manage the balance between FES and robotic controllers. Combination of FES and robotic control is a challenging issue, due to the non-linear behavior of muscle under stimulation and the lack of developments in the field of hybrid control. In this article, a cooperative control strategy of a hybrid exoskeleton is presented. This strategy is designed to overcome the main disadvantages of muscular stimulation: electromechanical delay and change in muscle performance over time, and to balance muscular and robotic actuation during walking.Experimental results in healthy subjects show the ability of the hybrid FES-robot cooperative control to balance power contribution between exoskeleton and muscle stimulation. The robotic exoskeleton decreases assistance while adequate knee kinematics are guaranteed. A new technique to monitor muscle performance is employed, which allows to estimate muscle fatigue and implement muscle fatigue management strategies. Kinesis is therefore the first ambulatory hybrid exoskeleton that can effectively balance robotic and FES actuation during walking. This represents a new opportunity to implement new rehabilitation interventions to induce locomotor activity in patients with paraplegia.Acronym list: 10 mWT: ten meters walking test; 6 MWT: six minutes walking test; FSM: finite-state machine; t-FSM: time-domain FSM; c-FSM: cycle-domain FSM; FES: functional electrical stimulation; HKAFO: hip-knee-ankle-foot orthosis; ILC: iterative error-based learning control; MFE: muscle fatigue estimator; NILC: Normalized stimulation output from ILC controller; PID: Proportional-Integral-derivative Control; PW: Stimulation pulse width; QUEST: Quebec User Evaluation of Satisfaction with assistive Technology; SCI: Spinal cord injury; TTI: torque-time integral; VAS: Visual Analog Scale.
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PMID:Hybrid FES-robot cooperative control of ambulatory gait rehabilitation exoskeleton. 2459 2