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At least 487 records · Page 27Linked to original sources
PubMed2005

Optimization of pH controlled liquid hot water pretreatment of corn stover.

Controlled pH, liquid hot water pretreatment of corn stover has been optimized for enzyme digestibility with respect to processing temperature and time. This processing technology does not require the addition of chemicals such as sulfuric acid, lime, or ammonia that add cost to the process because these chemicals must be neutralized or recovered in addition to the significant expense of the chemicals themselves. Second, an optimized controlled pH, liquid hot water pretreatment process maximizes the solubilization of the hemicellulose fraction as liquid soluble oligosaccharides while minimizing the formation of monomeric sugars. The optimized conditions for controlled pH, liquid hot water pretreatment of a 16% slurry of corn stover in water was found to be 190 degrees C for 15 min. At the optimal conditions, 90% of the cellulose was hydrolyzed to glucose by 15FPU of cellulase per gram of glucan. When the resulting pretreated slurry, in undiluted form, was hydrolyzed by 11FPU of cellulase per gram of glucan, a hydrolyzate containing 32.5 g/L glucose and 18 g/L xylose was formed. Both the xylose and the glucose in this undiluted hydrolyzate were shown to be fermented by recombinant yeast 424A(LNH-ST) to ethanol at 88% of theoretical yield.

Cellulase↗
PubMed2001

The kidney in diabetes: how to control renal and related cardiovascular complications.

The clear-cut and detailed pathogenesis of diabetic renal disease is not yet elucidated, but it is clear that both initiation and progression of renal disease in diabetes is related to glycemic control and blood pressure (BP) regulation, also seen in intervention studies. Consequently, optimal control of glycemia and antihypertensive treatment have become the cornerstones in the management of patients with diabetes. Naturally, modulating factors need to be discussed in further detail. The genetics of diabetes and its renal complications are still very complex issues that need to be explored further. Few and inconclusive data are available with respect to clinical management, for which genotyping is not required. Dietary protein content has long been an interesting avenue for possible treatment, but to date, data from patients with nondiabetic renal disease and with diabetes are not totally convincing, although further results may be published very soon. The issue is also complex because a low-protein diet may increase BP according to new studies, rendering the issue of low-protein content in the diet still more complex and controversial. Metabolic issues remain a key question, specifically with regard to glycemic control, in which data have accumulated over the past decade from epidemiological and interventional studies. There is no doubt that optimal glycemic control is crucial, but issues regarding specific glucose-related mechanisms and protein and lipid metabolism are still under investigation. The renin-angiotensin system has emerged as a key issue in diabetes, especially with regard to its inhibition by angiotensin-converting enzyme (ACE) inhibition and angiotensin-receptor blockade. New studies suggest that more complete inhibition of this system by dual blockade may be an avenue for further study according to positive results in patients with microalbuminuric type 2 diabetes, who are at great risk. Antihypertensive treatment still remains a fundamental component, although the metabolic effects of some antihypertensive agents may be important, especially with respect to diuretics, ss-blockers, and possibly alpha-blockers. The situation becomes complex with the frequent combination of various agents in the treatment of hypertension in patients with diabetes. Conversely, ACE inhibitors may have some diabetes-protective effect, but further studies are needed.

Albuminuria↗
PubMed2004

Bioeffects of low-frequency ultrasonic gene delivery and safety on cell membrane permeability control.

OBJECTIVE: To develop a novel method of ultrasonic naked gene delivery (UNGD); to examine the relationship between optimal parameters of ultrasound exposure and cell membrane permeability, enzymes, and free radicals; and to find optimal control parameters that were realizable, reliable, and noncytotoxic for use in gene therapy. METHODS: Suspensions of chicken, rabbit, and rat red blood cells and S180 cells were exposed to a calibrated ultrasonic field with different parameters in both the still and flowing states to obtain optimal parameters for UNGD. The optimal parameters then were used to implement UNGD. We examined morphologic characteristics, membrane permeability, enzymes, free radicals, naked gene expression efficiency, cell damage threshold, and cell viability by laser scanning confocal microscopy, fluorescent microscopy, flow cytometry, and spectrophotometry. RESULTS: Green fluorescent protein (GFP) as a reporter was delivered into S180 cells under the optimal parameters without cell damage or cytotoxicity. The transfection rate (mean +/- SD) was approximately 35.83% +/- 2.53% (n = 6) in viable cells, and cell viability was 90.17% +/- 1.47% (n = 6). The intensity of GFP expression with UNGD showed a higher fluorescent peak over both an adeno-associated virus vector-GFP group and a control group (P < .001). Additionally, malondialdehyde, hydroxyl free radicals, alkaline phosphatase, and acid phosphatase displayed an S-shaped growth model (r = 0.98 +/- 0.01) in response to permeability and morphologic alteration. CONCLUSIONS: Under optimal conditions, low-frequency ultrasound can safely deliver naked genes into cells without causing cell damage. The analytical results indicate that, except for subcavitation, free radical products are responsible for bioeffects in gene delivery. The constant E of energy deposition at 90% cell viability is the optimal control factor, and 80% viability represents the damage threshold. Optimal gene uptake by cells and safety depend on E. Constant E can be applied to control the gene delivery effect in combination with other parameters.

Animals↗
PubMed2003

Position of the American Dietetic Association: integration of medical nutrition therapy and pharmacotherapy.

It is the position of the American Dietetic Association that the application of medical nutrition therapy (MNT) and lifestyle counseling as a part of the Nutrition Care Process is an integral component of the medical treatment for management of specific disease states and conditions and should be the initial step in the management of these situations. If optimal control cannot be achieved with MNT alone and concurrent pharmacotherapy is required, then The Association promotes a team approach to care for clients receiving concurrent MNT and pharmacotherapy and encourages active collaboration among dietetics professionals and other members of the health care team. There are a number of medical conditions, many of them chronic, that will respond to MNT and, therefore, MNT should be the first intervention for these conditions. In addition to being a vital element of the optimal management and control of these conditions, MNT is also a cost-effective method of management. However, because of the long-term nature of these conditions, concurrent pharmacotherapy may become necessary to achieve or maintain optimal control. In cases where this is necessary, MNT should continue to be an integral component of the therapy because it may complement or enhance the therapeutic effectiveness of pharmacotherapy, thereby reducing or eliminating the need for multiple medications. The utilization of a coordinated multidisciplinary team approach is critical to the success of the concurrent use of MNT and pharmacotherapy because of the long-term duration of the treatments, the necessity of monitoring compliance and effectiveness, and the likelihood of multiple medication-nutrient interactions.

Chronic Disease↗
PubMed2002

Identifying older diabetic patients at risk of poor glycemic control.

BACKGROUND: Optimal glycemic control prevents the onset of diabetes complications. Identifying diabetic patients at risk of poor glycemic control could help promoting dedicated interventions. The purpose of this study was to identify predictors of poor short-term and long-term glycemic control in older diabetic in-patients. METHODS: A total of 1354 older diabetic in-patients consecutively enrolled in a multicenter study formed the training population (retrospective arm); 264 patients consecutively admitted to a ward of general medicine formed the testing population (prospective arm). Glycated hemoglobin (HbA1c) was measured on admission and one year after the discharge in the testing population. Independent correlates of a discharge glycemia > or = 140 mg/dl in the training population were assessed by logistic regression analysis and a clinical prediction rule was developed. The ability of the prediction rule and that of admission HbA1c to predict discharge glycemia > or = 140 mg/dl and HbA1c > 7% one year after discharge was assessed in the testing population. RESULTS: Selected admission variables (diastolic arterial pressure < 80 mmHg, glycemia = 143-218 mg/dl, glycemia > 218 mg/dl, history of insulinic or combined hypoglycemic therapy, Charlson's index > 2) were combined to obtain a score predicting a discharge fasting glycemia > or = 140 mg/dl in the training population. A modified score was obtained by adding 1 if admission HbA1c exceeded 7.8%. The modified score was the best predictor of both discharge glycemia > or = 140 mg/dl (sensitivity = 79%, specificity = 63%) and 1 year HbA1c > 7% (sensitivity = 72%, specificity = 71%) in the testing population. CONCLUSION: A simple clinical prediction rule might help identify older diabetic in-patients at risk of both short and long term poor glycemic control.

Journal Article↗
PubMed2004

Manipulation of surface reaction dynamics by global pressure and local temperature control: a model study.

Specific catalyst design and external manipulation of surface reactions by controlling accessible physical or chemical parameters may be of great benefit for improving catalytic efficiencies and energetics, product yield, and selectivities in the field of heterogeneous catalysis. Studying a realistic spatiotemporal one-dimensional model for CO oxidation on Pt(110) we demonstrate the value and necessity of mathematical modeling and advanced numerical methods for directed external multiparameter control of surface reaction dynamics. At the model stage we show by means of optimal control techniques that species coverages can be adjusted to desired values, aperiodic oscillatory behavior for distinct coupled reaction sites can be synchronized, and overall reaction rates can be optimized by varying the surface temperature in space and time and the CO and O2 gas phase partial pressure with time. The control aims are formulated as objective functionals to be minimized which contain a suitable mathematical formulation for the deviation from the desired system behavior. The control functions pCO(t) (CO partial pressure), pO2(t) (O2 partial pressure), and T(x,t) (surface temperature distribution) are numerically computed by a specially tailored optimal control method based on a direct multiple shooting approach which is suitable to cope with the highly nonlinear unstable mode character of the CO oxidation model.

Journal Article↗
PubMed2001

Postchallenge hyperglycemia in a national sample of U.S. adults with type 2 diabetes.

OBJECTIVE: Postchallenge hyperglycemia (PCH) is known to contribute to suboptimal glycemic control in adults with non-insulin-requiring type 2 diabetes. The objective of this study was to estimate the prevalence of PCH among individuals with diabetes. RESEARCH DESIGN AND METHODS: We conducted a cross-sectional analysis of data from the Third National Health and Nutrition Examination Survey (1988-1994) in adults aged 40-74 years with diabetes who were not using insulin (i.e., they used oral hypoglycemics or received no pharmacological therapy). Each respondent underwent a standard 75-g oral glucose tolerance test. PCH was defined as a 2-h glucose level >or=200 mg/dl. RESULTS: Overall, PCH was present in 74% of those with diagnosed diabetes. Although it was present in virtually all (99%) of the diabetic adults under suboptimal glycemic control (HbA(1c) >or=7.0%), PCH was also common (39%) among those under optimal control (HbA(1c) <7.0%). Likewise, among sulfonylurea users, PCH was present in 99% of those under suboptimal control and in 63% of those under good control. Similar patterns were observed in those with undiagnosed diabetes. Isolated PCH (2-h glucose >or=200 mg/dl and fasting glucose <126 mg/dl) was present in 9.8% of the adults with diagnosed diabetes. CONCLUSIONS: These data suggest that PCH is common among diabetic adults in the U.S., even in the setting of "optimal" glycemic control and sulfonylurea use. Interventions designed to lower postprandial glucose excursions may help improve overall glycemic control in the general population of U.S. adults with diabetes.

Adult↗
PubMed2006

The use of random controls in genetic association studies.

BACKGROUND: The optimal control sample would be ethnically-matched and at minimal risk of developing the disease. Alternatively, one could collect random individuals from the population or select individuals to reduce the number of at-risk individuals in the sample. The effect of randomly selected individuals in a control sample on the statistical power and the odds ratio estimate was investigated. METHODS: Case and control genotype distributions were simulated using standard genetic models with an additional term representing the proportion of unidentified cases in the control sample. Power and odds ratio were calculated from the genotype distributions generated under different sampling scenarios using established methods. RESULTS: Random sampling of controls resulted in a loss in power and a reduction in the odds ratio estimate to a degree that is determined by the proportion of random sampling and the prevalence of the disease. Random sampling resulted in a 19% loss in power for a disease having prevalence of 0.20, compared to a control sample that contained no at-risk individuals. Having random controls results in a decrease in the odds ratio estimate. CONCLUSIONS: Investigators planning case-control genetic association studies should be aware of the statistical costs of different ascertainment approaches.

Alleles↗
PubMed2002

Design PID controllers for desired time-domain or frequency-domain response.

Practical requirements on the design of control systems, especially process control systems, are usually specified in terms of time-domain response, such as overshoot and rise time, or frequency-domain response, such as resonance peak and stability margin. Although numerous methods have been developed for the design of the proportional-integral-derivative (PID) controller, little work has been done in relation to the quantitative time-domain and frequency-domain responses. In this paper, we study the following problem: Given a nominal stable process with time delay, we design a suboptimal PID controller to achieve the required time-domain response or frequency-domain response for the nominal system or the uncertain system. An H(infinity) PID controller is developed based on optimal control theory and the parameters are derived analytically. Its properties are investigated and compared with that of two developed suboptimal controllers: an H2 PID controller and a Maclaurin PID controller. It is shown that all three controllers can provide the quantitative time-domain and frequency-domain responses.

Computer Simulation↗
PubMed2004

Design and robustness of delayed feedback controllers for discrete systems.

We study a matrix form of time-delay feedback control in the context of discrete time maps of high dimension. In almost all cases where standard proportional feedback control methods can achieve control, time-delay feedback controllers containing only static elements can be designed to achieve identical linear stability properties. Analysis of an example involving a ring of coupled maps that can be controlled at only two sites demonstrates that the time-delay controller equivalent to a standard optimal controller can be equally robust in the presence of noise, except at special points in parameter space where the uncontrolled system has a mode with Floquet multiplier exactly equal to 1. Numerical simulations confirm the results of the analysis.

Journal Article↗
PubMed2006

Origin inactivation in bacterial DNA replication control.

Initiation of DNA replication is a highly regulated process in all organisms. Proteins that are required to recruit DNA polymerase - initiator proteins - are often used to regulate the timing or frequency of initiation in the cell cycle by limiting either their own synthesis or availability. Studies of the Escherichia coli chromosome and of bacterial plasmids with iterated initiator binding sites (iterons) have revealed that, in addition to initiator limitation, replication origin inactivation is used to prevent replication that is untimely or excessive. Our recent studies of plasmid P1 revealed that this additional mode of control becomes a requirement when initiator availability is limited only by autoregulation. Thus, although initiator limitation appears to be a well-conserved and central mode of replication control, optimal replication might require additional control mechanisms. This review gives examples of how the multiple mechanisms can act synergistically, antagonistically or be partially redundant to guarantee low frequency events. The lessons learned are likely to help understand many other regulatory systems in the bacterial cell.

Bacterial Proteins↗
PubMed1998

Development of a progestin-based estrus synchronization program: II. Reproductive response of cows fed melengestrol acetate for 14 days with injections of progesterone and prostaglandin F2alpha.

We tested the efficacy of an estrus control system designed to provide optimal control of follicular development. In Exp. 1, postpartum cows (n = 133) and yearling heifers (n = 57) were fed either .5 mg x female(-1) x d(-1) of melengestrol acetate (MGA) or the carrier for MGA from d -13 to d 0 (d 0 = last day of MGA feeding). All females received 25 mg of PGF2alpha (i.m.) on d -13 and 0. On d -6, cows and heifers fed MGA were administered an i.m. injection of progesterone (200 mg; MGA/P4), and those fed the corn carrier (2XPGF2alpha) received no progesterone. Beginning on d 1, females were bred by AI from d 1 to at least d 5. During the estrus synchronization period (d 1 to d 5), more (P < .05) postpartum cows were observed in estrus (70.1 vs 42.4%), the timing of estrus was more (P < .05) precise, conception rate was similar, and pregnancy rate was higher (P < .05) in the MGA/P4 than in the 2XPGF2alpha treatment. More (P < .05) cows that were anestrous at the beginning of the breeding season were in estrus during the synchronization period in the MGA/P4 (55.8%) than in the 2XPGF2alpha (28.6%) treatment. In heifers, estrus was synchronized in over 90% of females, and neither conception nor pregnancy rate during the synchronization period differed between treatments. In Exp. 2, postpartum cows (n = 122) and heifers (n = 84) received treatments (MGA/P4 or 2XPGF2alpha) as described for Exp. 1 with one exception. In the MGA/ P4 treatment, progesterone was administered on d -7 rather than d -6. Females were bred by AI from d 1 to 5. The estrus response and conception rate during the synchronization period did not differ between treatments for either cows or heifers. We conclude that the progestin-based estrous synchronization system used in this study effectively synchronized an estrus of normal fertility in cyclic cows and induced a majority of anestrous cows to reinitiate estrous cycles.

Administration, Oral↗
PubMed2006

Horizons in prosthesis development for the restoration of limb function.

The focus of our research program is the restoration of limb function through a biohybrid approach. We consider the limb conceptually as a biohybrid organ consisting of biological tissue, endoprostheses (including neural devices and joint replacements), and exoprostheses. The biohybrid limb maximizes biological function and functional articulations with optimized human-prosthesis interfaces. Our long-term goals are to create biomimetic prostheses, optimized control systems for prostheses, and optimized human-prosthesis interfaces using both limb lengthening and osseointegration techniques.

Amputation, Surgical↗
PubMedDate not supplied

[Evolution of life cycle: models based on optimization of energy allocation].

A brief history of optimization approach in modern evolutionary ecology is given and author's own results concerning life history evolution are considered in more details. The problem of evolutionary optimization is formulated in terms of mathematical theory of optimal control as a problem of optimal sharing of organism's resources between growth, reproduction, repair, and maintenance. The Malthusian parameter is used as optimality criterion. This approach allows, in particular, to give evolutionary ecological explanations for some well known empirical facts such as attenuation of growth with age (law of Bertalanffi), acceleration of ageing with age (law of Gompertz), human sexual dimorphism in mean lifespan, age and size of maturity.

Aging↗
PubMed1979

Influence of a between-run component of variation, choice of control limits, and shape of error distribution on the performance characteristics of rules for internal quality control.

A computer-stimulation study has been performed to determine how the performance characteristics of quality-control rules are affected by the presence of a between-run component of variation, the choice of control limits (calculated from within-run vs. total standard deviations), and the shape of the error distribution. When a between-run standard deviation (Sb) exists and control limits are calculated from the total standard deviation (St, which includes Sb as well as the within-run standard deviation, Sw), there is generally a loss in ability to detect analytical disturbances or errors. With control limits calculated from Sw, there is generally an increase in the level of false rejections. The presence of non-gaussian error distribution appears to have considerably less effect. It can be recommended that random error be controlled by use of a chi-square or range-control rule, with control limits calculated from Sw. Optimal control of systematic errors is difficult when Sb exists. An effort should be made to reduce Sb, and this will lead to increased ability to detect analytical errors. When Sb is tolerated or accepted as part of the baseline state of operation for the analytical method, then further increases in the number of control observations will be necessary to achieve a given probability for error detection.

Chemistry, Clinical↗
PubMed1983

[Diabetes mellitus: the role of metabolic control in the prevention of complications].

Recent studies have cast doubt on the idea, generally agreed but not unequivocally proven, that optimal control of diabetes could delay or prevent the development of late microangiopathic complications of the disease. In particular, a perfect equilibration of glycemic values could, in certain cases, deteriorate, rather than improve, the situation (pre-proliferative retinopathy). Through a review of literature the authors try to answer the following questions: is diabetic microangiopathy due to hereditary factors? Can the treatment of diabetes influence the appearance of late "triopathic" complications? If yes, could an optimal metabolic control result in a stop or a regression of these lesions? Based on the available data, the authors reach the conclusion that yes, it is worthwhile to treat correctly diabetes mellitus and, if possible, a perfect glycemic control should be sought. There are only few and well determined exceptions to this rule. In insulin dependent diabetics a perfect control can presently be obtained by means of conventional intensified insulin treatment (multiple injections) or of continuous subcutaneous insulin infusion (insulin pump) for variable periods of time.

Animals↗
PubMed1978

Clinical efficacy of valproic acid in relation to plasma levels.

Valproic acid is a new antiepileptic drug recently introduced in the United States for the treatment of absence seizures. In this study on patients with absence and other seizure types, the majority of patients achieved optimal control within four weeks of therapy. No patient responded to valproic acid who did not show an initial clinical response by four weeks of active therapy. Optimal response was generally achieved when plasma levels were greater than 55 microgram/ml. Excellent clinical response was observed in the treatment of absence and myoclonic seizures. Twenty-two patients continued in a long term study have maintained the same degree of seizure control as observed at the time of optimal control.

Adolescent↗