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PubMed1986

The translational efficiency of tRNA is a property of the anticodon arm.

We have reciprocally transplanted the anticodon arm sequences of a set of amber suppressor tRNA genes, using recombinant DNA techniques. By this means, a very efficient suppressor may be converted to a poor one, and the poorest tRNA to the efficiency of the best one. In tRNA molecules of normal 2 degrees and 3 degrees structure, the suppressor efficiencies of different composite tRNAs having the same anticodon arm sequence are approximately the same. Large numbers of simultaneous changes throughout the rest of the molecule do not affect the efficiency. Selective nucleotide modification as a result of varied anticodon arm sequences cannot explain these efficiencies. Efficiencies are also unlikely to differ because of selective aminoacylation. Measurement of in vivo tRNA shows, however, that tRNA levels do vary if the anticodon arm sequence is changed. If tRNA levels are normalized, the anticodon arm effect on the translational efficiency remains. Therefore, different anticodon arms, all of normal secondary structure, are not equivalent in translation. The most efficient sequences in this series resemble those found in natural tRNAs associated with similar anticodons, as is proposed in the extended anticodon theory (Yarus, M. (1982) Science 218, 646-652). These molecules also provide some information on the specificity of nucleotide modification enzymes and on determinants of the steady-state tRNA level.

Anticodon↗

PubMed1986

Improved plating efficiencies for human tumors cloned in capillary tubes versus Petri dishes.

As now constituted, the human tumor cloning assay performed in Petri dishes has several limitations including: (a) not all patients' tumors form colonies in the assay; (b) the plating efficiencies (number of colonies formed/number of cells plated) are low; and (c) a large number of tumor cells are required to perform drug sensitivity testing. In this study the use of capillary tubes, as vessels in which to clone human tumors, is compared to the use of 35-mm Petri dishes. In 100-microliters capillary tubes the optimal plating efficiencies are found with 50,000 cells/vessel (500,000 cells/ml), while in 35-mm Petri dishes the optimal plating efficiencies are found with 500,000 cells/vessel (250,000 cells/ml). In head to head comparisons of plating efficiencies of 183 human tumors (18 different histological types), the median plating efficiency was 5-fold higher (range, 1.16-37.00) for the capillary tubes than for the Petri dishes. This improved plating efficiency was noted for nearly all of the histological tumor types examined. The improved plating efficiencies noted with the capillary system indicate that the Petri dish method may be too selective and not reflect the total number of clonogenic units in a human tumor. In addition, the higher plating efficiencies noted with the capillary system may be exploited to solve some of the problems noted with the conventional Petri dish method.

Cell Count↗

PubMed1983

Effect of acetaminophen on the leukocyte-labeling efficiency of indium oxine In 111.

The effect of acetaminophen on the labeling efficiency of leukocytes with indium oxine In 111 was studied. A blood sample was obtained from eight healthy men before and after they received acetaminophen 650 mg every four hours for 24 hours. After dividing the plasma from each sample into three portions, leukocytes were separated and labeled with indium oxine In 111. In an in vitro study, 200 ml of blood was obtained from one of the men, and the plasma was separated into four portions. Acetaminophen in 95% ethanol was added to three of the plasma fractions to produce acetaminophen concentrations of 4, 20, and 100 micrograms/ml; ethanol was added to the fourth fraction as a control. Each plasma fraction was then subdivided into three aliquots, and leukocytes were labeled as in the in vivo study. Mean leukocyte labeling efficiencies in both studies were calculated from the ratios of leukocyte radioactivity to initial radioactivity in the samples, expressed as percentages. Leukocyte labeling efficiencies before acetaminophen administration ranged from 79 to 85%; after administration, labeling efficiencies ranged from 70 to 87%. No significant differences in mean labeling efficiency before and after acetaminophen administration were noted in any of the subjects. Leukocyte labeling efficiencies in all in vitro plasma fractions were reduced, ranging from 54 to 63%, but no significant differences in labeling efficiency between any of the plasma fractions were found. Using the labeling procedures in this study, exposure of leukocytes from healthy men to acetaminophen in vivo or in vitro does not affect labeling efficiency with indium oxine In 111.

Acetaminophen↗

PubMed1981

Matching in epidemiologic studies: validity and efficiency considerations.

Validity and efficiency issues are considered with regard to the use of matching and random sampling as alternative methods of subject selection in follow-up and case-control studies. We discuss the simple situation involving dichotomous disease and exposure variables and a single dichotomous matching factor, and we consider the influence on efficiency of a possible loss of subjects due to matching constraints. The decision to match or not should be motivated by efficiency considerations. An efficiency criterion based on a comparison of confidence intervals under matching and random sampling for the effect measure of interest (the risk ratio and risk difference in follow-up studies, and the odds ratio in case-control studies) leads to the following conclusions when the sampling method does not influence the size of the comparison group. In follow-up studies, matching on a confounder is expected to lead to a gain in efficiency over random sampling, while matching on a nonconfounder is not expected to result in a loss of efficiency. In case-control studies, the same conclusions hold, except that matching is not as advantageous as in follow-up studies and can lead to a loss of efficiency in some situations (usually of little practical importance). When matching reduces the size of the comparison group, there is likely to be a meaningful gain in efficiency due to random sampling only when the matched comparison group is at most 40-50% the size of the randomly-sampled comparison group is a follow-up study, and at most 50-65% the size in a case-control study.

Follow-Up Studies↗

PubMed1995

Identification of heavy chain residues in a humanized anti-CD3 antibody important for efficient antigen binding and T cell activation.

A previously identified humanized anti-CD3 Ab variant, v9, binds T cells with > 100-fold higher efficiency than the original variant, v1, and almost as efficiently as a chimeric molecule containing corresponding murine variable domains. Variants v1 and v9 differ at six positions in the H chain second CDR. Here a mutational analysis was used to identify which of these six replacements are primarily responsible for the difference in binding efficiency. These anti-CD3 variants were used to probe the relationship between Ag binding efficiency and potency in stimulating T cell proliferation. The human to mouse mutations T57S and V63F increase the binding efficiency of variant v1 for T cells by 8- and 12-fold, respectively, and together in variant M18 enhance binding by 26-fold to within 4-fold of variant v9. A framework mutation, 169L, was identified that enhances the binding of variants v1 and M18 by 14- and 3-fold, respectively. The Ag binding efficiencies of anti-CD3 variants correlate directly with their potencies in stimulating the proliferative activity of both resting human PBMC and IL-2-activated human T lymphocytes. Humanized variant v9 is equipotent to the murine parent Ab in stimulating ATL activity. PBMC activated by variants v1 and v9 IgG in a short term culture are equally cytotoxic against human breast carcinoma cells. Thus, high efficiency Ag binding by anti-CD3 variants is important for stimulating efficient T cell proliferation, but not cytotoxicity, in vitro.

Amino Acid Sequence↗

PubMed1995

Retroviral end-point titer is not predictive of gene transfer efficiency: implications for vector production.

Efforts to improve gene transfer (transduction) efficiency achieved with retroviral vectors often focus on increasing the end-point titer. In this study, we assayed more than 70 retroviral vector supernatants for end-point titer and for the ability to transfer reporter genes into cell populations (referred to as transduction efficiency). We found no correlation between end-point titer and transduction efficiency. We also show that increasing end-point titer by ultrafiltration does not necessarily increase transduction efficiency. Evidence presented shows that nontransducing retroviral particles interfere with transducing virions and reduce transduction efficiency without reducing end-point titer. We have investigated production parameters and stability of retroviral vector particles using transduction efficiency as a measure of supernatant potency. Analysis of the production kinetics showed that the rate of virus production was marginally higher at 37 degrees C than at 32 degrees C. However, recombinant amphotropic retrovirus particles are significantly more stable at 32 degrees C than at 37 degrees C. In addition, we show that short incubation periods are sufficient to yield supernatants with high transduction efficiencies. We have implemented improved culture conditions, including short incubation periods, by continually perfusing medium over producer cells in a packed-bed bioreactor incubated at 32 degrees C. By operating the packed-bed bioreactor in perfusion mode, retroviral vector supernatants with a high transduction efficiency can be routinely produced in large quantities.

3T3 Cells↗

PubMed1997

MHC class I-associated peptides produced from endogenous gene products with vastly different efficiencies.

We compared the efficiency of generating antigenic peptides from various polypeptide contexts expressed by recombinant vaccinia viruses. These included full-length influenza virus nucleoprotein (NP(1-498)), two truncated forms, and cytosolic and endoplasmic reticulum-targeted minimal peptides. Two peptides were studied, NP(50-57) (Kk-restricted) and NP(147-155) (Kd-restricted). The efficiency of peptide generation was measured in cytotoxicity assays by determining 1) the kinetics of presentation following infection using brefeldin A to block additional presentation and 2) the concentration of anti-class I mAbs required to block presentation. The two determinants behaved similarly, being presented most efficiently from minigene products, with intermediate efficiency from fragments, and least efficiently from NP(1-498). Direct quantitation of HPLC-purified peptides supported the validity of these simple methods to roughly estimate the efficiency of class I Ag presentation. It also surprisingly revealed that 60- to 90-fold more NP(50-57) than NP(147-155) peptide was present in cells expressing NP(1-498) or a rapidly degraded fragment (for NP(1-498), 1800 peptides/cell of NP(50-57) vs 30 peptides/cell of NP(147-155)). By contrast, nearly identical (and much greater) amounts of peptides were recovered from cells expressing minigene products (55,000 copies of either peptide/cell). These findings demonstrate 1) that immunodominant peptides from the same protein can be generated with vastly different efficiencies, and 2) that cytosolic or endoplasmic reticulum-targeted minigene products are presented far more efficiently than longer polypeptides.

Animals↗

PubMed1997

Contributions of increased efficiency and capacity of protein synthesis to rapid cardiac growth.

Rapid cardiac growth depends upon faster synthesis than degradation of protein. The rate of protein synthesis is determined by the efficiency with which the existing components of the ribosome cycle make protein and by the quantity of the components that are present. The tissue content of RNA is taken as an index of the capacity of synthesis and efficiency is expressed as the amount of protein formed per amount of RNA over a certain time period. The efficiency of synthesis is regulated by hormones, including insulin, agents that increase cAMP, alpha-adrenergic agonists, endothelin I and angiotensin II. In addition, provision of non-carbohydrate substrates and mechanical factors such as stretch and contraction increase efficiency. Impaired energy availability as occurs in anoxic or ischemic muscle decreases efficiency. Increased phosphorylation of ribosomal protein, S6, or of the peptide chain initiation factor, elF-4E, have been suggested as mechanisms to regulate efficiency of mRNA translation. Increased efficiency of synthesis accounts for cardiac growth in the first few days following aortic banding, pulmonary artery constriction and thyroxine administration. Decreased efficiency accounts for cardiac atrophy in heterotopic transplanted hearts during the first 3 days following transplantation. The capacity of synthesis is increased by insulin, thyroid hormone, activators of protein kinase C, agents that increase cAMP, and endothelin-1. Stretch of the ventricular wall and contraction of cultured neonatal myocytes accelerates ribosome formation. An increased rate of ribosomal DNA transcription accounts for accelerated ribosome formation and depends on increased activity of a transcription factor, upstream binding factor (UBF). The activity of UBF is increased either by increased rates of synthesis or by phosphorylation of the protein. Increased capacity of synthesis is a major contributor to rapid cardiac growth in the newborn heart and after several days of pressure overload.

Animals↗

PubMed2026

Measuring economic efficiency in adult intensive care units: A systematic review of methods, metrics, and evidence.

OBJECTIVES: Intensive care units (ICUs) consume substantial hospital resources, yet "efficiency" is inconsistently defined and measured. This study systematically reviewed how economic efficiency has been conceptualised and quantified in adult ICUs and appraised the quality of evidence. METHODS: Following PRISMA 2020 and a PROSPERO-registered protocol (CRD420251107866), we searched MEDLINE, Embase, CINAHL, Cochrane Library and Web of Science (2000-August 2025), plus global grey sources. Eligible studies explicitly defined efficiency and reported an efficiency metric/model linking ICU inputs (e.g., staff, beds/capacity, time, consumables, or costs) to outputs/outcomes (e.g., throughput/discharges, length of stay/resource use, risk-adjusted mortality). Dual independent screening and extraction were performed. Study quality was appraised using MMAT, and findings were synthesised narratively (SWiM), given heterogeneity. RESULTS: 39 studies (2001-2025) from 17 countries were included, all from high-income or upper-middle-income settings. Four methodological families were identified: (1) frontier modelling (predominantly DEA; occasional SFA/RFDH), (2) benchmarking indicators (risk-adjusted mortality and LOS/resource-use ratios; "efficiency matrix" quadrant classification), (3) cost-outcome evaluations, and (4) operational/process metrics. Across families, variation in decision-making units, input/output selection, and risk adjustment limited comparability; long-term and patient-reported outcomes were absent, and equity considerations were uncommon. CONCLUSIONS: ICU efficiency research is feasible but fragmented and often methodologically limited. Standardised definitions, validated risk adjustment, uncertainty quantification, and inclusion of patient-centred and equity-relevant outcomes are needed before efficiency metrics can reliably inform value-based decision making.

Intensive Care Units↗

PubMed1994

Trends in Department of Defense hospital efficiency.

This study employs a simple cross sectional design using longitudinal data to explore the underlying factors associated with differences in hospital technical efficiency using data envelopment analysis (DEA) in the Department of Defense (DOD) sector across three service components, the Army, Air Force and Navy. The results suggest that the services do not differ significantly in hospital efficiency. Nor does hospital efficiency appear to differ over time. With respect to the efficient use of input resources, the services experienced a general decline in excessive usage of various inputs over the three years. Analysis of the returns to scale captures opportunities for planners of changing the relative mix of output to input slacks for increasing a hospital's efficiency. That is, policy makers would get more immediate "bang per buck" with emphasis on improving the efficiencies of hospitals with higher returns to scale than other hospitals. Findings also suggest a significant degree of comparability between the DEA measure and these measures often used to indicate efficiency.

Ambulatory Care↗

PubMed2005

Institutional arrangements and efficiency of health care delivery systems.

This study examined the efficiency of health care delivery systems in 24 OECD countries. Practicing physicians, practicing nurses, inpatient beds, and pharmaceuticals were considered as inputs to treat populations of various age groups. Data envelopment analysis (DEA) was utilized to calculate efficiency. We also calculated input efficiency that should be helpful in determining excess number of physicians, nurses, inpatient beds, and pharmaceuticals consumed. Institutional arrangements affect efficiency: public-contract and public-integrated countries are more efficient than public-reimbursement countries. Countries in which physicians are paid in wages and salaries and countries with capitation have higher efficiency than fee-for-service countries. Countries in which a primary care physician acts as a gatekeeper are also more efficient than countries without gatekeepers.

Delivery of Health Care↗

PubMed2026

Efficient scarless gene editing in Pichia pastoris via survival stress-based intramolecular homologous recombination.

To overcome low efficiency and/or genomic instability induced by DNA cleavage in current genome-editing approaches, a novel pop-in/pop-out-based editing system was developed for Pichia pastoris. An ingenious arrangement of components leads to a more efficient screening by permitting the only type of DNA recombination under defined pressure conditions, in terms of the overall efficiency of gene editing, the system virtually depends on the integration efficiency mediated by single-crossover recombination. It does not rely on exogenous recombinases or programmable nucleases such as Cas9, thereby avoiding nuclease induced double strand breaks and associated off target mutations or chromatin fatigue. This strategy preserves high editing efficiency with no modification to the host's inherent genetic properties. Relative to site-specific recombination methods, its dual MazF counterselection enables seamless editing, avoiding scar sequence-induced genomic instability. In this study, nearly 100% knockout efficiency and over 86.67% integration efficiency were achieved in the described experimental cases with this system, which provides a new gene-editing tool for synthetic biology in Pichia pastoris.

Efficient scarless editing↗

PubMedDate not supplied

[Primary care: decentralization and efficiency].

OBJECTIVE: The purpose of this study was to evaluate whether the productive behavior of health centers in autonomous communities with competence in health is more efficient than that among centers belonging to Spanish public health system (INSALUD). METHODS: The technical efficiency of 66 health centers in Alava, Navarre and La Rioja was analyzed. Centers in autonomous communities that in 1997 had been granted complete authority from the central government to manage their healthcare services were compared with centers whose administration, in the same year, was still in the hands of INSALUD. The method used to measure and quantify the efficiency of these centers was data envelopment analysis. RESULTS: Nonparametric contrast of the health centers' mean efficiency rates revealed no significant differences in the (in)efficiency of centers from La Rioja, Navarre and Alava. CONCLUSIONS: The results obtained from the model of efficiency measurement used did not indicate that decentralization improves the productive efficiency of primary care centers.

Efficiency, Organizational↗

PubMed2001

Measuring efficiency of long-term care units in Finland.

Data Envelopment Analysis (DEA) was used to measure the nursing care efficiency of 64 long-term care units in Finland. New approaches introduced for evaluating efficiency were unit/ward level analysis, and the case-mix classification Resource Utilization Groups (RUG-III). Efficiency determinations were based on four DEA measures: cost, technical, allocative, and scale efficiency. The results indicated considerable variation in efficiency between units, suggesting that efficiency could be improved through better management and allocation of resources. Larger units seemingly operated more efficiently than smaller units. Allocative inefficiency resulted from using too many registered nurses and aides, and too few licensed practical nurses.

Cost-Benefit Analysis↗

PubMed1999

A descriptive assessment of the production and cost efficiency of general hospitals in Greece.

This paper focuses on the assessment of alternative aspects of the efficiency of 98 out of 126 hospitals of the Greek national health system. The analysis is directly concerned with the degree of utilisation of resources and the production efficiency of the general hospitals selected. For the measurement of the indices of efficiency, the internationally known method of Data Envelopment Analysis (modified to the particular characteristics of the Greek NHS) was used. The efficiency of Greek hospitals was assessed utilising two alternative conceptual models: one focusing on production and the other on cost efficiency. The results, in both cases, indicated the scope for substantial efficiency improvements. The analysis has sought to discuss the policy implications resulting from the current efficiency status of the hospitals with reference to issues of resource re-allocation and optimal scale size.

Cost-Benefit Analysis↗

PubMed2005

The association between quality of care and technical efficiency in long-term care.

OBJECTIVE: To analyse the association between quality of care and technical (productive) efficiency in institutional long-term care wards for the elderly. SETTING: One hundred and fourteen public health centre hospitals and residential homes in Finland. STUDY DESIGN: Wards were divided into two categories according to their rank in the quality distribution, considering 41 quality variables separately. The technical efficiency scores of the good- and poor-quality groups were compared using cross-sectional data. METHODS: Data envelopment analysis was used for calculating technical efficiency. The Mann-Whitney test and correlation coefficients were used to explore the association between quality and efficiency. RESULTS: The wards where quality indicators indicated less pro-active (passive) nursing practice and more dependent patients-for instance, in terms of very high prevalence of bedfast residents or very high prevalence of daily physical restraints-performed more efficiently than the comparison group. CONCLUSION: The results suggest that an association may exist between technical efficiency and unwanted dimensions of quality. Hence, the efficiency and quality of care are essential aspects of management and performance measurement in elderly care.

Aged↗

PubMed1997

Metabolic efficiency during arm and leg exercise at the same relative intensities.

This study was conducted to compare gross efficiency (GE), net efficiency (NE), work efficiency (WE), and delta efficiency (DE) between arm crank and cycle exercise at the same relative intensities. Eight college-aged males underwent two experimental trials presented in a randomized counterbalanced order. During each trial subjects performed three intermittent 7-min exercise bouts separated by 10-min rest intervals on an arm or semirecumbent leg ergometer. The power outputs for the three bouts of arm crank or cycle exercise corresponded to 50, 60, and 70% of the mode-specific VO2peak. GE, NE, and WE were determined as the ratio of Kcal.min-1 equivalent of power output to Kcal.min-1 of total energy expended, energy expended above rest and energy expended above unloaded exercise, respectively. DE was determined as the ratio of the increment of Kcal.min-1 of power output above the previous lower intensity to the increment of kcal.min-1 of total energy expended above the previous lower intensity. GE and NE did not differ between arm crank and cycle exercises. However, WE was lower (P < 0.05) during arm crank than cycle exercise at 50, 60, and 70% VO2peak. DE was also lower (P < 0.05) during arm crank than cycle exercise at delta 50-60 and at delta 60-70% VO2peak. It is concluded metabolic efficiency as determined by work and delta efficiency indices was lower during arm crank compared with cycle exercise at the same relative intensities. These findings add to the understanding of the difference in metabolic efficiency between upper and lower body exercise.

Adult↗

PubMed2001

Improving nutrient efficiency as a strategy to reduce nutrient surpluses on dairy farms.

Dutch nutrient policy aims at reducing leaching of agricultural nutrients by internalizing the negative externalities associated with inefficient nutrient use. This is done by taxation of nitrogen and phosphate surpluses that exceed a hectare-based threshold of maximum-allowed surpluses. One management strategy farmers may use to reduce the nutrient surpluses on their farms is to improve the nutrient efficiency of the agricultural production process. This study employs Data Envelopment Analysis (DEA) to calculate nitrogen and phosphate efficiencies and an overall nutrient efficiency measure for a 3-year panel of 114 Dutch dairy farms. Subsequent analyses show the impact of both farm intensity and nutrient efficiency on the nitrogen and phosphate surpluses. It appears that farm intensity has a positive effect on efficiency, but efficiency and intensity exert opposite influences on nutrient surpluses. This is especially the case for nitrogen. The magnitude of a possible reduction of nitrogen surpluses through a strategy of efficiency improvement is therefore limited by the intensity of the farming system, unless the technology with which nutrients are used by the farming system can be further improved or input/output ratios will be altered.

Animal Husbandry↗