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At least 235 records · Page 13Linked to original sources
PubMed2006

Electrokinetic migration of acidic drugs across a supported liquid membrane.

Electrokinetic cross membrane extraction of acidic drugs was demonstrated for the first time. The acidic drugs were extracted from an alkaline aqueous donor solution (300 microl), through a thin supported liquid membrane of 1-heptanol sustained in the pores of the wall of a porous hollow fiber, and into an aqueous alkaline acceptor solution (30 microl) present inside the lumen of the hollow fiber by the application of a d.c. electrical potential. The negative electrode was placed in the donor solution, and the positive electrode was placed in the acceptor solution. Optimal extractions were accomplished with 1-heptanol as the supported liquid membrane, with 50 V as the driving force, and with pH 12.0 in both the donor and acceptor solutions, respectively (NaOH). Equilibrium extraction conditions were obtained after 5 min of operation with the whole assembly agitated at 1200 rpm. Eleven different acidic drugs were extracted with recovery values between 8 and 100%, and initial data supported that electrokinetic cross membrane extraction provided repeatable data and linear response between original donor concentration and final acceptor concentration of the acidic model compounds.

Acids↗
PubMed1998

Which cutoff level should be used in screening for glucose intolerance in pregnancy? Definition of Screening Methods for Gestational Diabetes Study Group of the Lombardy Section of the Italian Society of Diabetology.

OBJECTIVE: Our purpose was to examine the validity of 140 mg/dL cutoff value in oral glucose challenge test screening for gestational diabetes mellitus when including in the group to be identified women fulfilling more inclusive Carpenter and Coustan criteria for 100-g oral glucose tolerance testing interpretation and gravid women with borderline glucose intolerance. STUDY DESIGN: We reanalyzed data of a multicenter study performed on 704 pregnant women screened at the twenty-fourth to twenty-eighth week with a 50-g oral glucose challenge test followed by a universal 100-g oral glucose tolerance test. We used receiver-operator characteristic curve analysis, assembling positive and negative groups according to the different criteria adopted in oral glucose tolerance test interpretation (National Diabetes Data Group or Carpenter-Coustan) and in assignment of women with borderline glucose intolerance. Besides the statistical cutoff value, defined by the Youden index (Sensitivity + Specificity - 1), we also selected a "high-sensitivity" cutoff value, identified by the maximal sensitivity associated with >70% specificity. RESULTS: With use of National Diabetes Data Group criteria, the statistical and high-sensitivity cutoff values were set at 142 mg/dL when the positive group included only women with positive oral glucose tolerance test results and at 140 mg/dL when it also included subjects with borderline glucose intolerance. With use of Carpenter-Coustan criteria, the statistical cutoff value was set at 141 mg/dL when the positive group included only women with positive oral glucose tolerance test results and at 140 mg/dL when it also included subjects with borderline glucose intolerance; the high-sensitivity cutoff value was set at 140 mg/dL when the positive group included only women with positive oral glucose tolerance test results and at 136 mg/dL when it also included subjects with borderline glucose intolerance. CONCLUSIONS: We suggest maintaining the 140 mg/dL oral glucose challenge test threshold if the diagnostic target is to recognize only women with positive results of the oral glucose tolerance test. To prevent perinatal risks in pregnancies complicated by borderline glucose intolerance, with Carpenter-Coustan criteria a lower cutoff value (136 mg/dL) could be hypothesized to improve test sensitivity, allowing more extensive diagnosis of "borderline" subjects; however, the higher economic costs resulting from the increased false-positive rate and the limited improvement obtainable in sensitivity currently do not justify its generalized use.

Administration, Oral↗
PubMed2002

Binding and diffusion of CheR molecules within a cluster of membrane receptors.

Adaptation of the attractant response in Escherichia coli is attributable to the methylation of its transmembrane chemotactic receptors by the methyltransferase CheR. This protein contains two binding domains, one for the sites of methylation themselves and the other for a flexible tether at the C terminus of the receptor. We have explored the theoretical consequences of this binding geometry for a CheR molecule associated with a cluster of chemotactic receptors. Calculations show that the CheR molecule will bind with high net affinity to the receptor lattice, having a high probability of being attached by one or both of its domains at any instant of time. Because of the relatively low affinity of its individual domains and the close proximity of neighboring receptors, it is likely that when one domain unbinds it will reattach to the array before the other domain unbinds. Stochastic simulations show that the enzyme will move through the receptor cluster in a hand-over-hand fashion, like a gibbon swinging through the branches of a tree. We explore the possible consequences of this motion, which we term "molecular brachiation", for chemotactic adaptation and suggest that a similar mechanism may be operative in other large assemblies of protein molecules.

Binding Sites↗
PubMed2003

Interhemispheric cooperation for face recognition but not for affective facial expressions.

Interhemispheric cooperation can be indicated by enhanced performance when stimuli are presented to both visual fields relative to one visual field alone. This "bilateral gain" is seen for words but not pseudowords in lexical decision tasks, and has been attributed to the operation of interhemispheric cell assemblies that exist only for meaningful words with acquired cortical representations. Recently, a bilateral gain has been reported for famous but not unfamiliar faces in a face recognition task [Neuropsychologia 40 (2002) 1841]. In Experiment 1 of the present paper, participants performed familiarity decisions for faces that were presented to the left (LVF), the right (RVF), or to both visual fields (BVF). An advantage for BVF relative to both LVF and RVF stimuli was seen in reaction times (RTs) to famous faces, but this bilateral advantage was absent for unfamiliar faces. In Experiment 2, participants classified the expression (happy or neutral) of unfamiliar faces. No bilateral advantage was seen for expressions, although a right hemisphere superiority was seen in terms of higher accuracy for LVF and BVF trials relative to the RVF. Recognition of famous faces (but not of facial expressions) require access to acquired memory representations that may be instantiated via cortical cell assemblies, and it is suggested that interhemispheric cooperation depends on these acquired cortical representations.

Adolescent↗
PubMed1981

Cardiopulmonary resuscitation by medical and surgical house-officers.

In teaching hospitals the responsibility for cardiopulmonary resuscitation usually rests with the house-staff, yet most house-officers receive no formal training in life support. The life-support skills of 45 medical and surgical house-officers in a university teaching hospital were tested by means of simulated cardiac arrests. House-officers were graded on the basis of a performance checklist derived from the standards of the American Heart Association. No house-officer received a pass score in basic life support (BLS). Only 29% could properly compress and ventilate the mannequin. In advanced cardiac life support (ACLS) only one-third could intubate in 35 s or less; only 31%, 40%, and 33% could manage ventricular fibrillation, asystole, and complete heart block, respectively. Some house-officers were unable to operate the defibrillator or assemble resuscitation equipment. Many house-officers displayed helplessness and anxiety during the simulations; fourteen (40%) were prompted to register for additional advanced life-support courses. The performance of medical and surgical house-officers was equal. House-officers who had received prior life-support training performed better in BLS (p less than 0.001) but not in ACLS. It was concluded that (a) most medical and surgical house-officers are not reasonably proficient in BLS and ACLS, and (b) cardiac arrest simulation is a motivating exercise which permits analysis of each house-officer's life-support skills. House-officers should have more training and practice in life support, or they should not have primary responsibility for cardiopulmonary resuscitations.

Clinical Competence↗
PubMed1997

Effects of coronally slotted femoral prostheses on cortical bone strain.

The photoelastic method was used to assess the effects on femoral cortical strain of total hip arthroplasty cementless femoral prostheses containing distal coronal slots. Eight cadaveric femurs were tested, although three were eliminated secondary to fractures. Loaded and unloaded cortical strains were determined at 72 points on the implanted femoral cortex and compared with the values obtained in the intact femur. Three different prostheses were sequentially implanted, in a random order, into each femur. The prostheses consisted of a standard solid stem, an identical stem with a coronal slot in its distal one fourth, and an identical stem with a coronal slot in its distal one half. The slotted stems did not enhance axial load transfer to the proximal medial femur but did result in increased proximal medial assembly strains and statistically significant (P < .05) decreased anterior and posterior assembly strains. The increased proximal medial assembly strains are hypothesized to enhance proximal medial femoral loading, while the decreased anterior and posterior assembly strains may minimize operative implantation fractures.

Aged↗
PubMed1990

Kinetic analysis of tubulin exchange at microtubule ends at low vinblastine concentrations.

We have investigated the effects of vinblastine at micromolar concentrations and below on the dynamics of tubulin exchange at the ends of microtubule-associated-protein-rich bovine brain microtubules. The predominant behavior of these microtubules at polymer-mass steady state under the conditions examined was tubulin flux, i.e., net addition of tubulin at one end of each microtubule, operationally defined as the assembly or A end, and balanced net loss at the opposite (disassembly or D) end. No dynamic instability behavior could be detected by video-enhanced dark-field microscopy. Addition of vinblastine to the microtubules at polymer-mass steady state resulted in an initial concentration-dependent depolymerization predominantly at the A ends, until a new steady-state plateau at an elevated critical concentration was established. Microtubules ultimately attained the same stable polymer-mass plateau when vinblastine was added prior to initiation of polymerization as when the drug was added to already polymerized microtubules. Vinblastine inhibited tubulin exchange at the ends of the microtubules at polymer-mass steady state, as determined by using microtubules differentially radiolabeled at their opposite ends. Inhibition of tubulin exchange occurred at concentrations of vinblastine that had very little effect on polymer mass. Both the initial burst of incorporation that occurs in control microtubule suspensions following a pulse of labeled GTP and the relatively slower linear incorporation of label that follows the initial burst were inhibited in a concentration-dependent manner by vinblastine. Both processes were inhibited to the same extent at all vinblastine concentrations examined. If the initial burst of label incorporation represents a low degree of dynamic instability (very short excursions of growth and shortening of the microtubules at one or both ends), then vinblastine inhibits both dynamic instability and flux to similar extents. The ability of vinblastine to inhibit tubulin exchange at microtubule ends in the micromolar concentration range appeared to be mediated by the reversible binding of vinblastine to tubulin binding sites exposed at the polymer ends. Determination by dilution analysis of the effects of vinblastine on the apparent dissociation rate constants for tubulin loss at opposite microtubule ends indicated that a principal effect of vinblastine is to decrease the dissociation rate constant at A ends (i.e., it produces a kinetic cap at A ends), whereas it has no effect on the D-end dissociation rate constant.

Animals↗
PubMed2004

Self-interacting domains in the C terminus of a cation-Cl- cotransporter described for the first time.

The first isoform of the Na+-K+-Cl- cotransporter (NKCC1), a widely distributed member of the cation-Cl- cotransporter superfamily, plays key roles in many physiological processes by regulating the ion and water content of animal cells and by sustaining electrolyte secretion across various epithelia. Indirect studies have led to the prediction that NKCC1 operates as a dimer assembled through binding domains that are distal to the amino portion of the carrier. In this study, evidence is presented that NKCC1 possesses self-interacting properties that result in the formation of a large complex between the proximal and the distal segment of the cytosolic C terminus. Elaborate mapping studies of these segments showed that the contact sites are dispersed along the entire C terminus, and they also led to the identification of a critical interacting residue that belongs to a putative forkhead-associated binding domain. In conjunction with previous findings, our results indicate that the uncovered interacting domains are probably a major determinant of the NKCC1 conformational landscape and assembly into a high order structure. A model is proposed in which the carrier could alternate between monomeric and homo-oligomeric units via chemical- or ligand-dependent changes in conformational dynamics.

Amino Acid Sequence↗
PubMed2005

Chronic compartment syndrome, an important cause of work-related upper limb disorder.

OBJECTIVES: Work-related upper limb disorders (WRULD) are common and disabling complaints in industry, but a tissue diagnosis can be difficult where the pain is diffuse and variable, and this prevents effective treatment. Diffuse arm pain is frequently found in those doing rapid or strenuous repetitive work, such as factory assembly workers or keyboard operators. Similar symptoms occur in the legs in athletes, where chronic compartment syndrome (CCS) is a recognized entity, so we investigated the possibility that this might also be caused by prolonged repetitive work. METHODS: Patients were selected if they were unable to continue with work because of chronic forearm pain. They were divided into three groups: 42 patients with symptoms consistent with CCS as defined in the text, 15 volunteers and patients with other arm complaints, and 10 asymptomatic arms of patients with unilateral CCS. We measured the pressure inside the extensor muscle compartment of the forearm at rest and after a 2 min repetitive gripping exercise using an electronic pressure-sensitive probe. RESULTS: The results show that CCS is a common and disabling forearm complaint associated with prolonged repetitive work. Fifteen patients have now had decompressive surgery on the extensor muscle compartment with good relief of symptoms. CONCLUSION: CCS is responsible for chronic peripheral neurological dysfunction in addition to muscle pain, and awareness of this diagnosis allows early identification and treatment of a currently unrecognized disorder with potential resolution of a long-lasting arm disability.

Adult↗
PubMed1968

A disposable anaerobic system designed for field and laboratory use.

A disposable anaerobic system which is characterized by its light weight and its compactness is described. The system consists of a multilayer plastic bag with a unique sealing device. A collapsible impregnated cardboard container is fitted with a catalyst and holders for a disposable hydrogen generator and an anaerobic indicator. The catalyst is active at room temperature and requires no heat activation. This system, which lends itself readily to compact storage, quick assembly, and ease of operation, is disposable after use.

Bacteria↗
PubMed1994

Applied comparative anatomy of the avian middle ear.

The anatomy of the middle ear has been studied in nine species of birds, with particular reference to the structure of the ossicle and its relationship to the tympanic membrane. The morphology of the avian middle ear has been compared to that of the reconstructed human middle ear. Drum to stapes foot plate assemblies created during ossiculoplasty operations differ from the pattern found in the avian middle ear in a number of important respects and this may help to explain why they are often unsuccessful. It is not technically feasible to reproduce the avian middle ear pattern exactly in the human middle ear and developments in reconstructive technique should therefore be directed towards reproducing the three ossicle pattern of the mammalian ear.

Anatomy, Comparative↗
PubMed2005

Implementation of a high-speed face recognition system that uses an optical parallel correlator.

We implement a fully automatic fast face recognition system by using a 1000 frame/s optical parallel correlator designed and assembled by us. The operational speed for the 1:N (i.e., matching one image against N, where N refers to the number of images in the database) identification experiment (4000 face images) amounts to less than 1.5 s, including the preprocessing and postprocessing times. The binary real-only matched filter is devised for the sake of face recognition, and the system is optimized by the false-rejection rate (FRR) and the false-acceptance rate (FAR), according to 300 samples selected by the biometrics guideline. From trial 1:N identification experiments with the optical parallel correlator, we acquired low error rates of 2.6% FRR and 1.3% FAR. Facial images of people wearing thin glasses or heavy makeup that rendered identification difficult were identified with this system.

Algorithms↗
PubMed1999

[Laparoscopic hernioplasty--personal experience].

The place of minimally invasive surgery in the treatment of inguinal hernias is still unequivocal so far. The authors submit the results assembled in 400 patients operated by the method of transabdominal preperitoneal implantation of a prolene net (TAPP) in the course of five years. They pay special attention to the incidence of relapses, peroperative and postoperative complications.

Adolescent↗
PubMedDate not supplied

Cutting costs without drawing blood.

When looking for ways to cut costs, most managers reach for the head-count hatchet, and the markets usually roar with approval. But a company can almost always create far more sustainable value by rigorously evaluating the small-ticket capital items that often get rubber-stamped. Drawing on his experience as a consultant and providing numerous anecdotes, the author contends that those "little" requests often prove to be gold plated or unnecessary. A disciplined evaluation involves asking only eight questions and conducting postmortems--regular audits of units' capital spending. But the payoff is enormous. Because cutting the capital budget increases cash flow, the author argues that a permanent cut of just 15% in the planned level of capital spending could boost some companies' market capitalization by as much as 30%. The first three questions--Is this your investment to make? Does it really have to be new? How are our competitors meeting compliance needs?--are asked of operating managers as they assemble capital project requests. The next three are asked by senior managers of themselves and their colleagues as they examine proposals: Is the left hand duplicating investments made by the right? Are trade-offs between profit and capital spending well understood? Are there signs of budget massage? At the end of the review process, senior managers ask: Are we fully using shared assets? How fine-grained are our capacity measures? The author's suggestions for the postmortem include searching for systematic problems with whole classes of expenditures and making sure audit teams come up with specific recommendations for change.

Budgets↗
PubMedDate not supplied

[Determination of aromatic polycyclic hydrocarbons during the installation of bituminous acoustic insulation panels].

Two kinds of bituminous European and Asiatic origin panels, used as acoustic insulators in the production of electrical household appliances have been analysed. The tests, made at 180 degrees C, operation temperature during the assembly phases, have been executed by sampling the smokes released during the thermal treatment, subsequently analysed by GC-MS. The results showed a marked difference between the two samples in the amount of the issued compounds, essentially constituted by alkyl-aromatic hydrocarbons, IPA and Alkyl-IPA.

Construction Materials↗
PubMed1999

Telemedicine and surgical robotics: urologic applications.

Medical treatment can be improved through integration and application of advances in technology, computers, and engineering. Accuracy and reliability are essential characteristics of any mechanical system, and with the evolution of machines capable of precise movements, the integration of medicine and machine is achievable. Early mechanical devices were effective in performing simple, repetitive tasks but were not sophisticated enough for independent function. In the automobile industry, robots could work on the assembly line executing these cyclic tasks. These machines could execute simple, reiterative movements without integrating new information from the environment. In this day and age, robots have evolved into sophisticated mechanical devices that can "react" to data detected in the environment to determine the next course of events. They have evolved from the assembly line to the operating room, assisting surgeons during surgery to participating in remote telesurgical procedures.

Journal Article↗
PubMedDate not supplied

Felix-M18 microcomputer-controlled automation of spectrofluorometric measurements with applications in virology.

A system consisting of an Aminco SPF-500 spectrofluorometer interfaced to the Felix-M18 microcomputer was used in the automation of spectrofluorometric measurements with applications in virology. Programs, routines and subroutines in BASIC and in assembly language allow the operation of the spectrofluorometer and the processing of photometric data. The high efficiency of the system is illustrated by an application: the characterization of the fluorescence anisotropy value in polarized light of an influenza virus suspension preincubated with a fluorescent probe.

Computers↗