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At least 757 records · Page 42Linked to original sources
PubMed2002

Urinary release of 72 and 92 kDa gelatinases, TIMPs, N-GAL and conventional prognostic factors in urothelial carcinomas.

OBJECTIVES: A urinary release of gelatinases A and B matrix metalloproteinases-2, -9 (MMP-2, -9), and tissue inhibitors (TIMP-1, -2) occurs during normal epithelial turnover. A proteinase increase, reduced inhibitors or both potentially account for cell mobility and bladder cancer progression. In order to define normal levels and thresholds for transitional cell carcinoma (TCC) patients, urinary gelatinases, tissue inhibitors and neutrophil-gelatinase-associated lipocalin (N-GAL) were investigated for end-point clinical status and compared with normal subjects during a 2-year follow-up prospective study. METHODS: Urine specimens [50 adult normal controls; 28 in situ carcinoma patients (pTa) and 23 with ruptured basement membrane (pT1-4)] were screened by gelatin zymograms, immunoblots and ELISA. RESULTS: (1) An important release of inhibitors over low levels of active enzymes was observed in controls independently of age and sex except for higher TIMP-1 levels in males. (2) In cancer patients, increased pro-MMP-9 and active MMP-2 with reduced TIMP-2 levels correlated with higher stages and histological grades. (3) Conversely, reduced MMP-9 and lipocalin levels were initial hallmarks of clinical relapses. CONCLUSIONS: The imbalance between increased MMP-2, -9 and decreased TIMP-2 levels appears to be linked to tumor stage and grade and, more importantly, to clinical events. Changes in the MMP-9 activation state and a lack of N-GAL present as novel markers of tumor progression.

Adult↗
PubMed1985

High-performance liquid chromatography with electrochemical detection of gossypol in human plasma.

A sensitive and selective high-performance liquid chromatographic method with electrochemical detection for the determination of gossypol in human plasma is described. Glutathione is used as a protective agent and gossypol dimethyl ether as an internal standard. Acetonitrile-treated protein-free plasma sample is first introduced on to a C18 pre-column for enrichment and clean-up. By using a column-switching technique, gossypol and the internal standard are subjected to further separation on a C8 analytical column, while the major interfering components are eliminated before entering the column. Methanol-0.1 M citrate buffer (pH 3.2) (80:20) is used as the mobile phase. The detector potential on the glassy carbon electrode is maintained at +0.6 V vs. an Ag-AgCl reference electrode. The linearity with human plasma ranged from 5 to 250 ng/ml. The absolute recoveries of gossypol and gossypol dimethyl ether were 91.3 and 97.5%, respectively, with a within-day precision of 2.5% and a day-to-day precision of 3.8%. The limit of detection is 5 ng/ml (signal-to-noise ratio = 3:1). The method is considered to be suitable for the clinical pharmacokinetic studies of gossypol.

Chromatography, High Pressure Liquid↗
PubMed2003

A wheelchair modified for leg propulsion using voluntary activity or electrical stimulation.

A commercially available wheelchair has been modified for propulsion by movements of the lower legs. The feet are attached securely to a foot rest that can rotate around the knee joint. Movement is generated either with residual voluntary activation of the quadriceps (knee extensor) and hamstring (knee flexor) muscles, or with electrical stimulation of these muscles, if voluntary control is absent. Either a chain or a lever can couple the movements through a gearbox to the wheel to propel the wheelchair forward. Control of a wheelchair with the legs is more efficient than using the arms and has the potential to increase the mobility and whole-body fitness of many wheelchair users, but there is considerable variability between subjects. To address this variability, we measured for individual subjects the passive properties of the legs and foot at rest (effective stiffness and viscosity), the length-tension (torque-angle) properties of the active muscle groups, as well as their force-velocity curve and their activation and fatigue rates. The measured values were then inserted into a model of the leg-propelled wheelchair. The purpose of this paper is to test whether the model could predict the performance of individual subjects accurately and could be used, for example, to optimize the speed of the wheelchair for a given subject.

Computer-Aided Design↗
PubMed1990

Microemulsion structure and its effect on electrochemical reactions.

Changes in the microstructure of oil-in-water microemulsions were identified electrochemically by using ferrocene derivatives, methyl viologen, and ferricyanide as the electroactive probes. Microdroplets as well as the bicontinuous microstructure were detected. This was accomplished by determining diffusion coefficients of the probes. Use of probes of different hydrophobicity/hydrophilicity and charge made it possible to investigate different microenvironments of microemulsions including oil, water, and surfactant/cosurfactant interface. Electrochemical reversibility of the probes was affected by the structure and appeared to reflect the ease of mobility across interphases. Reaction potential (E1/2) of the probes depended on the composition of the microemulsion.

Cetrimonium↗
PubMed2006

Electrostatic switching of biopolymer layers. Insights from combined electrokinetics and reflectometric interference.

Structural integrity and functional characteristics of biomacromolecules are largely defined by electrostatic forces between ionized moieties, which are often altered at interfaces. Unraveling these changes requires access to charge state and structure of surface-confined biopolymers in aqueous environments. We therefore combined electrokinetic measurements of interfacial electrical potentials with the simultaneous determination of the optical layer thickness by reflectometric interference spectroscopy. Two examples are summarized to demonstrate the resulting options: The pH-switching of grafted poly(l-glutamic acid) layers caused by dissociation-dependent helix-coil transitions was studied; potential distribution and ion mobility within the grafted polyelectrolyte were unraveled using an new theoretical model for the charging of polyelectrolyte layers. The charge-driven modulation of biopolymers at interfaces was furthermore analyzed in the adsorption of fibronectin onto polymer substrates with varied charge density; the results permit us to reach a conclusion about the relevance of electrostatic matching for orientation and anchorage of the protein. Altogether, the introduced methodology was found suitable to follow the electrosurface characteristics of biomacromolecules in situ.

Biopolymers↗
PubMed2002

Implications of alcohol partitioning behavior for in situ density modification of entrapped dense nonaqueous phase liquids.

Surfactant-based remediation techniques have the potential to be very effective for removing dense nonaqueous-phase liquids (DNAPLs) from contaminated sites. However, a risk associated with surfactant-based remediation of DNAPLs is the potential for unwanted downward mobilization of the DNAPL contaminants, making them more difficult to remove from the subsurface. The work described here examines the use of hydrophobic alcohol solutions to reduce the densities of entrapped DNAPLs, converting them to light nonaqueous-phase liquids (LNAPLs). Results of partitioning studies are presented for alcohol-DNAPL systems, in the absence and presence of surfactants. Results indicate that alcohol concentrations near saturation are necessary for conversion of DNAPLs to LNAPLs--particularly for high-density DNAPLs such as trichloroethylene (TCE) and tetrachloroethylene (PCE). Although surfactants can increase the mass of alcohol that can be delivered to a contaminated zone, they appear to change the partitioning equilibrium such that higher alcohol concentrations are required to achieve the same result. Results of this work indicate the importance of minimizing dilution during density modification applications and suggest the concept of using an alcohol macroemulsion flood for density conversion. Implications of the results of this work for remediation system design are discussed.

Environmental Monitoring↗
PubMed2004

Effect of soil properties on the degradation of isoxaflutole and the sorption-desorption of isoxaflutole and its diketonitrile degradate.

The transformation of isoxaflutole (ISOX) to its herbicidally active diketonitrile degradate (DKN) was significantly enhanced in the presence of soil and occurred more rapidly in systems containing soil with a greater soil pH. Sorption-desorption of ISOX and DKN in five soils collected within a field revealed both ISOX and DKN were more readily sorbed to soils with greater organic matter, clay content, and lower soil pH. Sorption of ISOX residues occurred within 2 h, and extracts contained similar concentrations of ISOX and DKN at 24 h, suggesting the 24-h sorption coefficients for ISOX-treated systems were actually for mixed ISOX residues. Freundlich sorption coefficients were 3 and 4 times greater for ISOX than for DKN. On the basis of the Freundlich organic carbon sorption constants, ISOX and DKN can be categorized in the very high and high mobility classes, suggesting their potential to leach in the soils needs to be evaluated.

Adsorption↗
PubMed1996

Efficient integration of an intron RNA into double-stranded DNA by reverse splicing.

Some group II introns are mobile elements as well as catalytic RNAs. Introns aI1 and aI2 found in the gene COX1 in yeast mitochondria encode reverse transcriptases which promote site-specific insertion of the intron into intronless alleles ('homing'). For aI2 this predominantly occurs by reverse transcription of unspliced precursor RNA at a break in double-strand DNA made by an endonuclease encoded by the intron. The aI2 endonuclease involves both the excised intron RNA, which cleaves the DNA's sense strand by partial reverse splicing; and the intron-encoded reverse transcriptase which cleaves the anti-sense strand. Here we show that aI1 encodes an analogous endonuclease specific for a different target site compatible with the different exon-binding sequences of the intron RNA. Over half of aI1 undergoes complete reverse splicing in vitro, thus integrating linear intron RNA directly into the DNA. This unprecedented reaction has implications for both intron mobility and evolution, and potential genetic engineering applications.

Base Sequence↗
PubMed2003

Inositol 1,3,4,5-tetrakisphosphate is essential for T lymphocyte development.

Inositol 1,4,5-trisphosphate (Ins(1,4,5)P(3)) is phosphorylated by Ins(1,4,5)P(3) 3-kinase, generating inositol 1,3,4,5-tetrakisphosphate (Ins(1,3,4,5)P(4)). The physiological function of Ins(1,3,4,5)P(4) is still unclear, but it has been reported to be a potential modulator of calcium mobilization. Disruption of the gene encoding the ubiquitously expressed Ins(1,4,5)P(3) 3-kinase isoform B (Itpkb) in mice caused a severe T cell deficiency due to major alterations in thymocyte responsiveness and selection. However, we were unable to detect substantial defects in Ins(1,4,5)P(3) amounts or calcium mobilization in Itpkb(-/-) thymocytes. These data indicate that Itpkb and Ins(1,3,4,5)P(4) define an essential signaling pathway for T cell precursor responsiveness and development.

Animals↗
PubMed1997

A case-control study of percutaneous nephrolithotomy versus extracorporeal shock wave lithotripsy.

OBJECTIVES: To assess the relative efficacy of percutaneous nephrolithotomy (PCN) and extracorporeal shock wave lithotripsy (ESWL) in clearing stones and to examine factors which affected the results from each treatment. PATIENTS AND METHODS: The study comprised 390 patients treated with PCN who were compared to 618 patients treated with ESWL. Unconditional logistic regression analysis was used to compare the odds of success and failure in the PCN group with those in the ESWL group, whilst controlling for any potential effects of age, sex, laterality, presence of other stones, previous stone history, pre-operative treatment and centre. RESULTS: PCN was more successful in obtaining satisfactory results than ESWL with an odds ratio of 2.67 (P < 0.001, 95% confidence intervals 1.84-3.87). The odds ratio in favour of PCN was increased after controlling for differences by centre (odds ratio 5.18, 95% confidence intervals 2.89-9.16). No other factors significantly influenced the odds ratio. ESWL was less successful in treating stones > 2 cm in diameter compared to treating stones < 2 cm in diameter (P = 0.001). ESWL results were also affected by re-treatment rates, which were influenced by distance of the local hospital from the lithotripter. The results with PCN improved with experience. The results of ESWL were satisfactory and the treatment cheaper, with a lower morbidity and hospital stay than after PCN for stones < 2 cm in diameter, making it the treatment of choice. However for stones > 2 cm, the results of ESWL were not as good and costs of treatment, morbidity and hospital stay were much closer to those of PCN for similar sized stones. CONCLUSIONS: PCN is more effective than ESWL in clearing stones. However, ESWL is an effective treatment and is usually the treatment of choice for most stones. Nevertheless, PCN remains an important and extremely effective method of treatment. The choice of treatment for stones will be influenced by the distance of a centre from a static lithotripter, and the potential availability of a mobile lithotripter.

Adolescent↗
PubMedDate not supplied

Deep vein thrombosis prophylaxis: the effectiveness and implications of using below-knee or thigh-length graduated compression stockings.

Potential complications of reduced mobility in both acute and chronically ill patients continue to challenge nurses on a daily basis. Deep vein thrombosis (DVT) is one of the most serious of these complications. Graduated compression stockings, also known as antiembolism stockings, are among the most commonly available and accepted methods of external compression for the prophylaxis of DVT. Currently, there are 2 lengths of graduated compression stockings in common use, thigh-length and below-knee. Although thigh-length stockings are widely perceived to be more effective in prophylaxis, difficulties associated with therapeutic application and maintenance are often encountered in different clinical settings. Below-knee stockings are easier to apply and maintain and appear to be tolerated better by patients. The aim of this article is to examine existing support for both lengths of stockings in terms of their effectiveness in DVT prophylaxis and to discuss the implications for practice.

Bandages↗
PubMed2002

Deep vein thrombosis prophylaxis: the effectiveness and implications of using below-knee or thigh-length graduated compression stockings.

Potential complications of reduced mobility in both acute and chronically ill patients continue to challenge nurses on a daily basis. Deep vein thrombosis (DVT) is one of the most serious of these complications. Graduated compression stockings, also known as antiembolism stockings, are among the most commonly available and accepted methods of external compression for the prophylaxis of DVT. Currently, there are 2 lengths of graduated compression stockings in common use, thigh-length and below-knee. Although thigh-length stockings are widely perceived to be more effective in prophylaxis, difficulties associated with therapeutic application and maintenance are often encountered in different clinical settings. Below-knee stockings are easier to apply and maintain and appear to be tolerated better by patients. The aim of this article is to examine existing support for both lengths of stockings in terms of their effectiveness in DVT prophylaxis and to discuss the implications for practice.

Bandages↗
PubMed2006

Magnetic resonance imaging with an optical atomic magnetometer.

We report an approach for the detection of magnetic resonance imaging without superconducting magnets and cryogenics: optical atomic magnetometry. This technique possesses a high sensitivity independent of the strength of the static magnetic field, extending the applicability of magnetic resonance imaging to low magnetic fields and eliminating imaging artifacts associated with high fields. By coupling with a remote-detection scheme, thereby improving the filling factor of the sample, we obtained time-resolved flow images of water with a temporal resolution of 0.1 s and spatial resolutions of 1.6 mm perpendicular to the flow and 4.5 mm along the flow. Potentially inexpensive, compact, and mobile, our technique provides a viable alternative for MRI detection with substantially enhanced sensitivity and time resolution for various situations where traditional MRI is not optimal.

Magnetic Resonance Imaging↗
PubMed1997

Regulation of the transforming growth factor beta-responsive transcription factor CTF-1 by calcineurin and calcium/calmodulin-dependent protein kinase IV.

Transforming growth factor beta (TGF-beta) is a pluripotent peptide hormone that regulates various cellular activities, including growth, differentiation, and extracellular matrix protein gene expression. We previously showed that TGF-beta induces the transcriptional activation domain (TAD) of CTF-1, the prototypic member of the CTF/NF-I family of transcription factors. This induction correlates with the proposed role of CTF/NF-I binding sites in collagen gene induction by TGF-beta. However, the mechanisms of TGF-beta signal transduction remain poorly understood. Here, we analyzed the role of free calcium signaling in the induction of CTF-1 transcriptional activity by TGF-beta. We found that TGF-beta stimulates calcium influx and mediates an increase of the cytoplasmic calcium concentration in NIH3T3 cells. TGF-beta induction of CTF-1 is inhibited in cells pretreated with thapsigargin, which depletes the endoplasmic reticulum calcium stores, thus further arguing for the potential relevance of calcium mobilization in TGF-beta action. Consistent with this possibility, expression of a constitutively active form of the calcium/calmodulin-dependent phosphatase calcineurin or of the calcium/calmodulin-dependent kinase IV (DeltaCaMKIV) specifically induces the CTF-1 TAD and the endogenous mouse CTF/NF-I proteins. Both calcineurin- and DeltaCaMKIV-mediated induction require the previously identified TGF-beta-responsive domain of CTF-1. The immunosuppressants cyclosporin A and FK506 abolish calcineurin-mediated induction of CTF-1 activity. However, TGF-beta still induces the CTF-1 TAD in cells treated with these compounds or in cells overexpressing both calcineurin and DeltaCaMKIV, suggesting that other calcium-sensitive enzymes might mediate TGF-beta action. These results identify CTF/NF-I as a novel calcium signaling pathway-responsive transcription factor and further suggest multiple molecular mechanisms for the induction of CTF/NF-I transcriptional activity by growth factors.

3T3 Cells↗
PubMed2004

The adaptor protein HSH2 attenuates apoptosis in response to ligation of the B cell antigen receptor complex on the B lymphoma cell line, WEHI-231.

Signals transduced by the B cell antigen receptor (BCR) play a central role in regulating the functional response of the cell to antigen. Depending on the nature of the antigenic signal and the developmental or differentiation state of the B cell, antigen receptor signaling can promote either apoptosis or survival and activation. Understanding the molecular mechanisms underlying BCR-mediated apoptosis constitutes an important area of research because aberrations in programmed cell death can result in the development of autoimmunity or cancer. Expression of the adaptor protein hematopoietic Src homology 2 (HSH2) was found to significantly decrease BCR-mediated apoptosis in the murine WEHI-231 cell line. Analysis of signal transduction pathways activated in response to BCR ligation revealed that HSH2 does not significantly alter total protein tyrosine phosphorylation or Ca2+ mobilization. HSH2 does not potentiate the activation-dependent phosphorylation of AKT either. With respect to MAPK activation, HSH2 was not observed to alter the activation of ERK or p38 in response to BCR ligation, but it does significantly potentiate JNK activation. Analysis of processes directly associated with apoptosis revealed that HSH2 inhibits mitochondrial depolarization to a significant degree, whereas it has only a slight effect on caspase activation and poly ADP-ribose polymerase cleavage. BCR-induced apoptosis of WEHI-231 cells is associated with the loss of endogenous HSH2 expression within 12 h, whereas inhibition of apoptosis in response to CD40-mediated signaling leads to stabilization of HSH2 expression. Thus, endogenous HSH2 expression correlates directly with survival of WEHI-231 cells, which supports the hypothesis that HSH2 modulates the apoptotic response through its ability to directly or indirectly promote mitochondrial stability.

Adaptor Proteins, Signal Transducing↗
PubMed2000

Text entry on handheld computers by older users.

Small pocket computers offer great potential in workplaces where mobility is needed to collect data or access reference information while carrying out tasks such as maintenance or customer support. This paper reports on three studies examining the hypothesis that data entry by older workers is easier when the pocket computer has a physical keyboard, albeit a small one, rather than a touch-screen keyboard. Using a counter-balanced, within-subjects design the accuracy and speed with which adults over 55 years of age could make or modify short text entries was measured for both kinds of pocket computer. The keyboard computer was the Hewlett Packard 360LX (HP), but the touch-screen computers varied across studies (experiment 1: Apple Newton and PalmPilot; experiment 2: Philips Nino; experiment 3: Casio E10). All studies showed significant decrements in accuracy and speed when entering text via the touch-screen. Across studies, most participants preferred using the HP's small physical keyboard. Even after additional practice with the touch screen (experiments 2 and 3) many entries still contained errors. Experiment 3 showed that younger people were faster but not more accurate than older people at using the touch-screen keyboard. It is concluded that satisfactory text entry on palm-size computers awaits improvements to the touch-screen keyboard or alternative input methods such as handwriting or voice. Interface developments that assist older people typically benefit younger users too.

Aged↗
PubMed2007

Adsorption kinetics of natural dissolved organic matter and its impact on arsenic(V) leachability from arsenic-loaded ferrihydrite and Al-ferrihydrite.

The present work was broadly divided into two parts: first, the efficiency of synthetically prepared ferrihydrite and Al-ferrihydrite to adsorb dissolved organic matter (DOM) was tested as a function of time, pH and ionic strength and its effects on specific surface area was found. In the second part, the effect of DOM concentration and solution pH was studied to elucidate the influence of this two parameters on As(V) leachability from As(V) loaded ferrihydrite and Al-ferrihydrite. It was found that both pH and ionic strength had significant influence on DOM adsorption. The behavior and magnitude of adsorption was significantly different for both the materials. In general, the efficiency of Al-ferrihydrite to adsorb DOM was better compared to ferrihydrite. Results indicated that ligand exchange was the dominant interaction mechanism for DOM adsorption on ferrihydrite and Al-ferrihydrite. The study also suggested a strong potential for DOM to mobilize As(V) from the studied materials. At pH 5.0, DOM concentrations of 2.5 and 5.0 mg C/L had negligible effect on As(V) leachability. With increasing DOM concentration from 10 to 30 mg C/L, increased the As(V) leachability into the solution. Net release from ferrihydrite was up to 1.07 mg/g (5.75%) of the total adsorbed arsenic. The corresponding figure for Al-ferrihydrite was 1.47 mg/g (6.30%). As the primary mechanisms for the arsenic release from solid phases we identified two different types of mechanisms i.e., dissolution of the solid phase and competition between arsenic and organic anions for sorption sites.

Adsorption↗
PubMed2003

The effect of propanil co-application on 2,4-D sorption by soil.

The herbicide 2,4-D is often applied as a tank mixture in combination with other herbicide products. However, current information on 2,4-D sorption by soil is largely based on batch-equilibrium experiments without considering the competition of other herbicides for sorption sites by soil. This study quantified the effect of the herbicide propanil on the sorption of 2,4-D in soil. Results indicated that propanil competed with 2,4-D for sorption sites, particularly in soils with an organic carbon content greater than 3.6%. The decrease in 2,4-D sorption by soil, as a result of propanil competition, was most notably for herbicide concentrations that are typical of recommended field rates. We conclude that herbicide co-applications on agricultural fields have the potential to increase the mobility of herbicides in soil.

2,4-Dichlorophenoxyacetic Acid↗