Optical mapping of lambda bacteriophage clones using restriction endonucleases

Optical mapping is an emerging single molecule approach for the rapid generation of ordered restriction maps, using fluorescence microscopy. We have improved the size resolution of optical mapping by imaging individual DNA molecules elongated and fixed onto derivatized glass surfaces. Averaged fluorescence intensity and apparent length measurements accurately determined the mass of restriction fragments 800 basepairs long. We have used optical mapping to create ordered restriction maps for lambda clones derived from the mouse pygmy locus.     

Contract balks

Fed up with insurers dictating contract terms, doctors are fighting back by putting the American Medical Association on the job. Yet the AMA's remedy--a bulky "model" agreement--may lack the power of persuasion.     

Cryptic self-association sites in type III modules of fibronectin

The first type III module of fibronectin (Fn) contains a cryptic site that binds Fn and its N-terminal 29 kDa fragment and is thought to be important for fibril formation (Morla, A., Zhang, Z., and Ruoslahti, E. (1994) Nature 367, 193-196; Hocking, D. C., Sottile, J. , and McKeown-Longo, P. J. (1994) J. Biol. Chem. 269, 19183-19191). A synthetic 31-mer peptide (NAPQ ... TIPG) derived from the middle of domain III1 was also shown to bind Fn, but the site of its interaction was not determined (Morla, A., and Ruoslahti, E. (1992) J. Cell Biol. 118, 421-429). By affinity chromatography on peptide-agarose, we tested a set of fragments representing the entire light chain of plasma Fn. Only 40-kDa Hep-2 (III12-15) failed to bind. The concentration of urea required for peak elution of Fn and the other fragments decreased in the order Fn > 42-kDa GBF (I6II1-2I7-9) > 19-kDa Fib-2 (I10-12) > 110-kDa CBF(III2-10) > 29-kDa Fib-1 (I1-I5). Neither Fn nor any of the fragments bound immobilized intact III1, confirming the cryptic nature of this activity. In an effort to detect interactions between other Fn domains, all fragments were coupled to Sepharose, and each fragment was tested on each affinity matrix before and after denaturation. The only interaction detected was that of fluid phase III1 with immobilized denatured 110-kDa CBF and 40-kDa Hep-2, both of which contain type III domains. Analysis of subfragments revealed this activity to be dominated by domains III7 and III15. Fn itself did not bind to the denatured fragments. Thus, domain III1 contains two cryptic "self-association sites," one that is buried in the core of the fold but recognizes many Fn fragments when presented as a peptide and another that is concealed in Fn but exposed in the native isolated domain and recognizes cryptic sites in two other type III domains. These interactions between type III domains could play an important role in assembly of Fn multimers in the extracellular matrix.     

Comprehensive reliability assessment and comparison of quality indicators and their components

To test whether conventional data reliability assessment overestimates reliability, an assessment and a comparison of the reliability of complex quality indicators and their simpler components were conducted. Medical records of 1078 Medicare cases with principal diagnoses of initial episodes of acute myocardial infarction (AMI) were independently reabstracted at two national Clinical Data Abstraction Centers (CDACs). The inter-rater agreement beyond chance (kappa) of reabstracted and original quality indicators and key components were computed and compared. Results showed excellent agreement (kappas ranging from 0.88 to 0.95) for simple determinations of whether standard medical therapies were provided. Repeatability of eligibility status and the more complex determinations of whether "ideal" candidates were not treated showed moderate to excellent kappa values ranging from 0.41 to 0.79. A planned comparison of five similar quality indicators and their key components showed that the simpler treatment components, as a group, had significantly higher kappas than the more complexly derived eligibility components and composite indicators (Fisher's exact, p < 0.02). Reliability assessment of quality indicators should be based upon the repeatability of the whole indicator, accounting for both data and logic, and not just one simple element.     

Global optimization of multicomponent distillation configurations: 2. Enumeration based global minimization algorithm

We present a general Global Minimization Algorithm (GMA) to identify basic or thermally coupled distillation configurations that require the least vapor duty under minimum reflux conditions for separating any ideal or near‐ideal multicomponent mixture into a desired number of product streams. In this algorithm, global optimality is guaranteed by modeling the system using Underwood equations and reformulating the resulting constraints to bilinear inequalities. The speed of convergence to the globally optimal solution is increased by using appropriate feasibility and optimality based variable‐range reduction techniques and by developing valid inequalities. The GMA can be coupled with already developed techniques that enumerate basic and thermally coupled distillation configurations, to provide for the first time, a global optimization based rank‐list of distillation configurations. © 2016 American Institute of Chemical Engineers AIChE J, 62: 2071–2086, 2016     

Plasma lipoprotein changes in suckling and weanling rabbits fed semipurified diets

The distribution and composition of the plasma lipoproteins were studied in suckling rabbits and in rabbits either weaned to or fed as young adults cholesterol-free, semipurified diets containing protein of animal (casein) or plant (soy protein isolate) origin. The raised cholesterol levels of the suckling period resulted in an increase of very low density and intermediate density lipoproteins in a manner similar to that seen in adult rabbits fed a high fat diet supplemented with cholesterol. Young rabbits fed the cholesterol-free, semipurified diet containing casein also became hypercholesterolemic but, in this case, the increased cholesterol was found primarily in lipoproteins of intermediate density. Cholesterol levels remained low in those rabbits fed the soy protein isolate diet, and the lipoprotein distribution was somewhat similar to that of chow-fed animals. It appears that the raised cholesterol levels during the suckling period result in different lipoprotein patterns to those produced in young adult animals by a cholesterol-free, semipurified diet.     

A multicenter study to improve emergency medicine residents' recognition of intracranial emergencies on computed tomography

STUDY OBJECTIVE: Cranial computed tomography (CT) has assumed a critical role in the practice of emergency medicine for the evaluation of intracranial emergencies. Several recent studies have documented a deficiency in the emergency physician's ability to interpret these studies. The purpose of this study was to quantify the baseline ability of emergency medicine residents to interpret cranial CTs, and to test a novel method of cranial CT interpretation designed for the emergency physician in training. METHODS: A standardized pretest was administered to assess baseline ability to interpret CT scans. A standardized posttest was given 3 months after the course. Each test consisted of 12 CT scans with a short accompanying history. All scans were validated by 3 expert reviewers for difficulty and diagnosis. A 2-hour course based on the mnemonic "Blood Can Be Very Bad" was then administered. "Blood" reminds the examiner to search for blood, "Can" prompts the examiner to identify 4 key cisterns, "Be" denotes the need to examine the brain, "Very" prompts a review of the 4 ventricles, and finally "Bad" reminds the examiner to evaluate the bones of the cranium. RESULTS: Eighty-three residents at 5 institutions were initially examined. The mean percentage correct before the course was 60% (95% confidence interval [CI] 58%-64%) on the standardized pretest. At retesting 3 months after the course, the accuracy rate increased to 78% (n=61, 95% CI 75%-81%, P<.001 paired t test). CONCLUSION: Emergency medicine residents are deficient in their ability to interpret cranial CT scans. A novel educational course was demonstrated to significantly improve this ability.     

Applications of shape memory alloys in optics

The application of shape memory alloy (SMA) thin films in optical devices is introduced and explored for the first time. Physical and optical properties of titanium-nickel (TiNi) SMA thin films change as these films undergo phase transformation on heating. An optical beam can be modulated either mechanically with a TiNi actuator or by the changes that occur in TiNi's optical properties upon heating and phase transformation. Reflection coefficients of TiNi films were measured in their so-called martensitic (room-temperature) and austenitic (elevated-temperature) phases. The reflection coefficients of the austenitic phase were higher than those of the martensitic phase by more than 45% in the wavelength range between 550 and 850 nm. Also, a microfabricated TiNi diaphragm with a 0.26-mm-diameter hole was used as a prototype light valve. The intensity of the transmitted light through the hole was reduced by 10%-17% when the diaphragm was heated. A novel TiNi light valve fabricated by using silicon micromachining techniques is also proposed and discussed. We present both optical data and structural data obtained by using transmission electron microscopies.     

Aquifer composition and the tendency toward scale-deposit formation during reverse osmosis desalination — examples from saline ground water in New Mexico, USA

Desalination is expected to make a substantial contribution to water supply in the United States by 2020. Currently, reverse osmosis is one of the most cost effective and widely used desalination technologies. The tendency to form scale deposits during reverse osmosis is an important factor in determining the suitability of input waters for use in desalination. The tendency toward scale formation of samples of saline ground water from selected geologic units in New Mexico was assessed using simulated evaporation. All saline water samples showed a strong tendency to form CaCO₃ scale deposits. Saline ground water samples from the Yeso Formation and the San Andres Limestone showed relatively stronger tendencies to form CaSO₄·2H₂O scale deposits and relatively weaker tendencies to form SiO_2(a) scale deposits than saline ground water samples from the Rio Grande alluvium. Tendencies toward scale formation in saline ground water samples from the Dockum Group were highly variable. The tendencies toward scale formation of saline waters from the Yeso Formation, San Andres Limestone, and Rio Grande alluvium appear to correlate with the mineralogical composition of the geologic units, suggesting that scale-forming tendencies are governed by aquifer composition and water-rock interaction.