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PubMed1999

Distinct cellular factors regulate the c-myb promoter through its E2F element.

Most E2F-driven promoters are transiently activated around the G(1)/S transition. Although the promoter for the c-myb proto-oncogene harbors an E2F element, it is induced early in G(1) following entry into the cell cycle. Furthermore, this promoter remains active throughout subsequent cell cycles. Since E2F sites function as repressor elements during G(1) (due to the association of pRb with E2F factors), we investigated whether the E2F element in the c-myb promoter is regulated differently than E2F elements in promoters that are repressed during G(1). By gel shift analysis, the E2F element from the c-myb promoter was found to form a unique complex, referred to as E2Fmyb-sp, which was not observed with E2F elements from several other promoters. Antibodies to DP-1, E2F1 to -5, p107, or pRb failed to either supershift or block E2Fmyb-sp complex formation. Methylation interference experiments indicate that the DNA contact residues for the E2Fmyb-sp complex are distinct from but overlapping with residues required for the binding of E2F proteins. In addition to the identification of E2Fmyb-sp, we have found that SP-1 binds to the c-myb E2F element. Functional studies revealed that E2Fmyb-sp and/or SP-1 are required to achieve full activation of the c-myb promoter in different cell types and to maintain elevated expression of the c-myb promoter during G(1) in NIH 3T3 cells. These studies demonstrate that E2F elements can be regulated differently through the binding of unique sets of proteins.

3T3 Cells↗
PubMed2000

[Optimization of the transition from phase II to III of cardiac rehabilitation].

A decisive element of reliable maintenance of the rehabilitation result achieved by patients undergoing inpatient cardiac rehabilitation has turned out to be comprehensive and successful management of the transition into the outpatient phase. This requires concrete planning and implementation of the concept, to be based on patient-related approaches and including the family physician, relatives, occupational institutions, and local and regional partners such as adult education centres, health insurances, sports clubs, psychological individual care, etc. Problem-orientated planning adapted to the individual requirements and expectations of the patient is of utmost importance.

Adult↗
PubMed2006

Kinetics of thermolysis of some transition metal nitrate complexes with 1,6-diaminohexane ligand.

Metal nitrate complexes of general formula [M(dah)(2)](NO(3))(2) (where M=Zn, Cu and Ni; dah=1,6-diaminohexane) have been prepared and characterized by elemental analysis, infrared spectroscopy (IR) and gravimetric method. The thermal decomposition has been studied using thermogravimetry (TG). Simultaneous thermogravimetry-differential thermogravimetry-differential thermal analysis (TG-DTG-DTA) and differential scanning calorimetry (DSC) were done in N(2) atmosphere. Isothermal TG of initial decomposition of all these complexes, have been carried out to evaluate the kinetics of early thermolysis. Both, model fitting and isoconversional method have been used for the evaluation of the kinetics of thermal decomposition. Model fitting method have given the single value of activation energy (E) whereas, isoconversional method yields a series of E-value, which vary with extent of conversion. Ignition of the complexes was measured to see the response towards rapid heating with varying amounts. The thermal stability of the complexes was found to be in the order as [Zn(dah)(2)](NO(3))(2)>[Cu(dah)(2)](NO(3))(2) approximately [Ni(dah)(2)](NO(3))(2).

Calorimetry, Differential Scanning↗
PubMed1997

Physicochemical properties and platelet interactions of segmented polyurethanes containing sulfonate groups in the hard segment.

The adhesion of platelets to a series of segmented polyurethanes having sulfonate groups in the hard segment is reported. The polyurethanes were synthesized using sulfonated chain extenders of different structure. Analogous control materials without sulfonate groups also were studied. Adhesion was measured in vitro using washed human platelets in a carrier fluid consisting of Tyrode's buffer with apyrase, albumin, and red cells at normal concentration. The polymers were characterized by gel permeation chromatography and elemental analysis. Water absorption and thermal transitions also were determined. It was found that the sulfonated materials absorb significant amounts of water while the nonsulfonated analogs do not. The surfaces of polymer films were characterized by water contact angle and XPS. The contact angles of the sulfonated surfaces were relatively low. Platelet adhesion to the sulfonated polymers was found to be very high compared to the nonsulfonate analogs. The local environment of the sulfonate groups (different chain extenders) also appears to have an effect on platelet interactions. Albumin adsorption was high on all the materials and was not correlated with platelet adhesion. It appears from this work that platelets may have a binding site that is specific for sulfonate groups.

Adsorption↗
PubMed2006

Bone microarchitecture of the calcaneus and its changes in aging: a histomorphometric analysis of 60 human specimens.

Bone structure and quality are an important parameter in the propensity of bone to fracture. Although the calcaneus is used as diagnostic reference site for osteoporosis by ultrasound, its structure has never been analyzed in detail. The purpose of this study was therefore to histomorphometrically analyze the trabecular microarchitecture of the calcaneus, and to determine whether the calcaneal bone structure is changing with age. Sixty complete human calcanei were harvested from thirty age- and gender-matched patients at autopsy. Each of the three different age groups (group I: 20 to 40, group II: 41 to 60, group III: 61 to 80 years of age) was represented by 20 specimens. The specimens were subjected to radiographic, microCT, and histologic analysis. Bone structure and bone mass of the calcaneus were quantified for three different regions of interest: the anterior ROI, the superior ROI (the subtalar region under the posterior facet), and the posterior ROI. An iliac crest biopsy was obtained from all patients to exclude any metabolic bone disease. Histomorphometric analysis revealed significant differences in bone volume within the calcaneus with highest values in the superior ROI: age group I: 31.3% (27.8-34.8%); II: 25.5% (22.1-28.9%); III: 18.9% (16.6-21.2%) and lowest bone volumes in the anterior ROI; age group I: 6.2% (4.8-7.6%); II: 3.6% (2.1-5.1%); III: 3.9% (2.9-4.9%). There was a significant age-related decrease in bone volume (BV/TV) in aging. Interestingly, this bone loss was most prominent in the superior ROI, with a 39% decrease in BV/TV between age group I and III (p < 0.001). Qualitative and structural analysis of trabecular number, thickness, and spacing demonstrated that the bone loss in the thalamic portion of the calcaneus was due to the transition of plate-like trabecular elements into a rod-like structure. In conclusion, our study demonstrated that the calcaneus displayed age-related changes in its microarchitecture that are known to reduce the biomechanical stability of trabecular bone, and that the age-related bone loss was most prominent in the region adjacent to the posterior facet (superior ROI). These results suggest that bone mass and structure are risk factors in respect to the occurrence and severity of calcaneal fractures, and indicate that calcaneal fractures are at least in part osteoporotic fractures.

Adult↗
PubMed1999

Lens proteins block the copper-mediated formation of reactive oxygen species during glycation reactions in vitro.

The formation of advanced glycation endproducts (AGEs) from glucose in vitro requires both oxygen and a transition metal ion, usually copper. These elements combine to produce reactive oxygen species (ROS) which degrade glucose to AGE-forming compounds. We measured the ability of Cu(2+) to accelerate ROS formation, and the effect of added lens proteins on these reactions. Increasing levels of Cu(2+) accelerated the formation of superoxide anion with glucose and fructosyl-lysine, but the addition of 2.0 mg/ml calf lens proteins completely blocked superoxide formation up to 100 microM of added Cu(2+). Lens proteins, however, had no effect on superoxide generated by the hypoxanthine/xanthine oxidase system. The oxidation of ascorbic acid was increased 170-fold by the addition of 10 microM Cu(2+), but was also completely prevented by added lens proteins. Hydroxyl radical formation, as measured by the conversion of benzoate to salicylate, was increased to 30 nmoles/ml after 18 h by the addition of 100 microM Cu(2+) and 2.5 mM H2O2. This increase was also blocked by the addition of lens proteins. However, hydroxyl radical formation, as estimated by the crosslinking and fragmentation of lens proteins, was observed in the presence of 100 microM Cu(2+), likely at the sites of Cu(2+) binding. Since the ratio of lens proteins to Cu(2+) in human lens is at least 1000-fold higher than those used here, the data argue that Cu(2+) in the lens would be tightly bound to protein, preventing ROS-mediated AGE formation from glucose in vivo.

Animals↗
PubMed1994

Molecular recognition by thrombin. Role of the slow-->fast transition, site-specific ion binding energetics and thermodynamic mapping of structural components.

The interaction of thrombin with the potent natural inhibitor hirudin is controlled in a complex fashion by the binding of Na+ and Cl- to the enzyme and allosteric transitions. Binding of hirudin is positively linked to Na+ binding, but is opposed in a competitive fashion by the binding of Cl-. Since Na+ binding induces the slow-->fast transition of thrombin, it follows from linkage principles that hirudin binds to the fast form with higher affinity. Hence, the slow-->fast transition is a key component of molecular recognition of hirudin by thrombin. We propose a three-step mechanism for molecular recognition of hirudin by thrombin, which is also relevant for recognition of fibrinogen and possibly the platelet receptor and thrombomodulin. First, the C-terminal acidic tail of hirudin binds to the fibrinogen recognition site of thrombin displacing one Cl ion from the thrombin surface. Then, the enzyme undergoes a conformational transition that gives rise to increased accessibility of the catalytic pocket to small synthetic substrates through movement of the Trp148 loop. The changes in the catalytic moiety triggered allosterically by binding to the fibrinogen recognition site are linked to the uptake of Na+ and are similar to, if not identical with, those observed in the Na(+)-induced slow-->fast transition. Finally, the compact N-terminal domain is accommodated in the region surrounding the catalytic pocket. Hirudin binding is also used as a probe of site-specific ion-binding interactions of Na+ and Cl- with the enzyme, characterized by cooperativity between the Na+ and Cl- binding domains. The structural components directly involved or linked to Na+ and Cl- binding have been explored in terms of free energy perturbations of the binding of hirudin and a number of ligands. The fibrinogen recognition site stores most of the free energy of coupling with Cl- binding, while regions surrounding the access to the catalytic pocket provide most of the free energy of coupling with Na+ binding and the slow-->fast transition of thrombin. It is concluded that thrombin is an allosteric enzyme that exists in two forms, slow and fast, and that the allosteric transition slow-->fast represents the key element of molecular recognition of important physiological substrates. The allosteric nature of the enzyme also enables different structural domains to communicate and give rise to biological function.

Amino Acid Sequence↗
PubMed1986

Correlation between total catecholamine content and redistribution of myosin isoenzymes in pressure loaded ventricular myocardium of the spontaneously hypertensive rat.

In the spontaneously hypertensive rat (SHR) with established hypertension left ventricular mass closely correlated with the proportion of ventricular myosin (VM)-3. A 60% VM-3 content was reached corresponding, under the present housing conditions, to an average age of 40 weeks without any significant change in total noradrenaline content. However, all 72-week-old SHR showed marked reduction in total noradrenaline content which corresponded to noradrenaline depletion. At this stage, the proportion of VM-3 varied greatly; some of the SHR exhibited a higher proportion of VM-3 than would be expected from their ventricular weight. The excessive redistribution in the direction of VM-3 might, therefore, be considered as a reaction secondary to noradrenaline depletion. Total dopamine content was also reduced in 72-week-old SHR. In younger SHR, a positive correlation was found for dopamine content and left ventricular weight. It is concluded that a redistribution of the myosin isoenzymes up to 60% VM-3 in SHR is not associated with deterioration of ventricular performance to the extent that an excessive neurohumoral drive ensues. However, in the late stage of haemodynamic overload, a functional state is reached which is prone to noradrenaline depletion. A causative factor involved in this process could be the extreme redistribution of the myosin isoenzyme population, besides other factors such as fibrosis and dilatation. Which functional determinants or structural elements are finally decisive for the transition into a myocardium with depleted noradrenaline stores requires further investigation.

Animals↗
PubMed1998

Thoracic geometry and its relation to electrical current distribution: consequences for electrode placement in electrical impedance cardiography.

In thoracic impedance cardiography (TIC) measurements the neck electrodes are often positioned at the basis of the neck, close to the neck-thorax transition. Theoretically, this neck-thorax transition will cause inhomogeneities in the current density and potential distribution. This was simulated using a 3D finite element method, solely representing the geometrical neck-thorax transition. The specific conductivity was 7 10(-3) (omega cm)-1 and the injected current was 1 mA. As expected, the model generated inhomogeneities in the current distribution at the neck-thorax transition, which reached as far as 5 cm into the neck and 20 cm into the thorax. These results are supported by in vivo measurements performed in 10 young male subjects, in which the position of the neck electrodes was varied. A two-way ANOVA revealed that the stroke volume of the lowest neck position was significantly different from the other positions. Small shifts in the position of the neck electrode resulted in large changes in impedance and stroke volume (127 to 82 ml for the Kubicek equation). To standardise the electrode position, the authors strongly recommend placement of the neck electrodes at least 6 cm above the clavicula.

Cardiography, Impedance↗
PubMed1998

Malignant phyllodes tumour with a noninvasive ductal carcinoma component.

A malignant phyllodes tumour with a noninvasive ductal carcinoma component is reported. The patient was an 80-year-old Japanese woman with a breast tumour detected by routine physical examination. A simple mastectomy was performed. The excised tumour was 10.5 x 9.4 x 5.4 cm in size and bulged into the skin with ulceration. The macroscopic appearance was that of a phyllodes tumour. Histologically the tumour consisted mainly of stromal components with a leaf-like structure lined by atypical ductal epithelium. The epithelial component showed gradual evolution to intraductal papillary carcinoma in a few areas. The stromal component was composed mainly of fibrosarcoma with areas of osteosarcoma and rhabdomyosarcoma. Neither stromal invasion of intraductal carcinoma nor transition between the stromal and epithelial elements was seen. Three months after the operation, death occurred, with multiple pulmonary and subcutaneous metastases. This case probably represents malignant change in both the stromal and the epithelial components of a phyllodes tumour. Since the two elements were independent, the possibility that a phyllodes tumour may be one of the origins of true carcinosarcoma is raised.

Aged↗
PubMed1991

Learning to express motion events in English and Korean: the influence of language-specific lexicalization patterns.

English and Korean differ in how they lexicalize the components of motion events. English characteristically conflates Motion with Manner, Cause, or Deixis, and expresses Path separately. Korean, in contrast, conflates Motion with Path and elements of Figure and Ground in transitive clauses for caused Motion, but conflates motion with Deixis and spells out Path and Manner separately in intransitive clauses for spontaneous motion. Children learning English and Korean show sensitivity to language-specific patterns in the way they talk about motion from as early as 17-20 months. For example, learners of English quickly generalize their earliest spatial words--Path particles like up, down, and in--to both spontaneous and caused changes of location and, for up and down, to posture changes, while learners of Korean keep words for spontaneous and caused motion strictly separate and use different words for vertical changes of location and posture changes. These findings challenge the widespread view that children initially map spatial words directly to nonlinguistic spatial concepts, and suggest that they are influenced by the semantic organization of their language virtually from the beginning. We discuss how input and cognition may interact in the early phases of learning to talk about space.

Concept Formation↗
PubMed1994

Hot and cold in transformation: is Iban medicine humoral?

Iban categories of hot and cold are examined in the context of humoral medical systems in southeast Asia. These categories are more than binary and oppositional: they are also contradictory and can only be understood in terms of their capacity for transformation in 'depth'. Analysis of the Iban epistemology of temperature sensation reveals the limitations of reductionist empirical approaches to hot and cold. Illness is apprehended, at one level, in terms of unusual conjunctions of opposite temperatures which signify a deeper disturbance in the relationship between body and soul, humans and spirits. Iban therapy redefines and relocates these categories in their proper place and at their appropriate level. It progresses from hot lay treatments to cool ritual treatments, yet cannot be accounted for within a limited framework of homeostatic balance. This paper develops an ethnographically grounded definition of humoralism which emphasizes non-reductive logic, cultural practice and transformation. The key element, transformation, is defined as a transition between categories and a shift in the level of interpretation which fundamentally alter the Iban experience of body and illness.

Borneo↗
PubMed2005

Effects of polymerization shrinkage on the interfacial stress at resin-metal joint in denture-base: a non-linear FE stress analysis.

OBJECTIVES: The purpose of this study was to investigate the effects of polymerization shrinkage on stress at the interface between resin and metal in removable dentures. METHODS: Three-dimensional finite element models of a denture-base were studied, which consisted of acrylic occlusal rims with different heights and metal frameworks. A relaxation modulus of 1.5 GPa for the resin and a Young's modulus of 220 GPa for the metal were used as the material properties. Each model was constrained at the edge of the framework on the palatal vault. Surface-to-surface contact elements were used to calculate the interfacial stress in a direction perpendicular to the bond surface under a linear shrinkage ranging from 0.41 to 0.65%. The principal stress within the resin was also calculated. RESULTS: The maximum interfacial and principal stresses within the denture-base increased with resin shrinkage. Under the lowest linear shrinkage, the mean area percentages in the resin-metal joint that showed interfacial tensile stresses over 10 and 20 MPa were 63.4 and 0%, respectively. While under the highest linear shrinkage, these mean area percentages were 98.8 and 38.1%, respectively. Negligible differences in the stresses were shown by occlusal heights. SIGNIFICANCE: The polymerization shrinkage level has a significant influence on the residual stress at the resin-metal interface. Enhancement of the bond strength on the interface can reduce the failure probability at a resin-metal joint.

Acrylic Resins↗
PubMed2004

Localization of the VEGF and angiopoietin genes in uterine carcinosarcoma.

OBJECTIVE: Carcinosarcoma of the uterus is a highly aggressive tumor. However, the angiogenesis in this tumor remains unclear. This is the first study to examine the characteristics of angiogenesis in this tumor at the molecular level while also comparing the findings with those of high-grade endometrial carcinoma. METHODS: The expression of vascular endothelial growth factors (VEGF) and angiopoietins (Ang) genes were examined in 35 primary uterine carcinosarcomas as well as in 12 high-grade endometrial carcinomas by in situ hybridization. RESULTS: A strong expression of VEGF-A mRNA was significantly seen in carcinosarcomas compared to high-grade endometrial carcinomas. Interestingly, in uterine carcinosarcoma, VEGF-A mRNA was more strongly expressed in the carcinoma cells than in the sarcoma cells. In addition, a decrease in the VEGF-A mRNA expression was found in the transitional areas between carcinomatous and sarcomatous elements in most carcinosarcomas evaluated. Moreover, the Ang-2 mRNA expression was significantly seen in the vasculature adjacent to the periphery of the carcinoma cells in most carcinosarcomas, in comparison to that of endometrial carcinomas. CONCLUSIONS: A high angiogenic activity in uterine carcinosarcoma was shown, in comparison to that of endometrial carcinoma. Tumor angiogenesis in uterine carcinosarcoma might be chiefly influenced by VEGF-A in the carcinoma cells, in cooperation with Ang-2 in the surrounding microvessels, however, this is not fully usually the case in sarcoma cells.

Aged↗
PubMed2000

Dynamic oscillation measurements of starch networks at temperatures above 100 degrees C.

Small deformation oscillatory studies were performed on wheat flour paste with a starch content of 75.4%. Work focused on temperatures above 100 degrees C in an effort to seek molecular understanding of such high-temperature processes as bakery operations which are characterised by evaporation of water. The moisture content of the sample decreased from about 32% at 100 degrees C to 6.5% at 130 degrees C. Viscoelastic spectra produced a sigmoidal profile with a disproportionate viscous element also seen in the glass transition of semiamorphous synthetic polymers and high sugar/polysaccharide mixtures during cooling. It is argued that the loss of water upon heating reduces the available free volume between neighbouring chain segments, thus generating a high-density thermoplastic melt suspending granule fragments. The configurational rearrangements of the disordered chains contribute mainly to an energy-dissipating process, as observed in the vitrification of cooled high-solids systems. The equation of Williams, Landel, and Ferry was modified with a 'moisture term' in order to describe the temperature function of viscoelasticity.

Carbohydrate Conformation↗
PubMed2002

Esterolytic antibodies as mechanistic and structural models of hydrolases-a quantitative analysis.

Understanding enzymes quantitatively and mimicking their remarkable catalytic efficiency is a paramount challenge. Here, we applied esterolytic antibodies (the D-Abs) to dissect and quantify individual elements of enzymatic catalysis such as transition state (TS) stabilization, nucleophilic reactivity and conformational changes. Kinetic and mutagenic analysis of the D-Abs were combined with existing structural evidence to show that catalysis by the D-Abs is driven primarily by stabilization of the tetrahedral oxyanionic intermediate of ester hydrolysis formed by the nucleophilic attack of an exogenous (solution) hydroxide anion. The side-chain of TyrH100d is shown to be the main H-bond donor of the D-Abs oxyanion hole. The pH-rate and pH-binding profiles indicate that the strength of this H-bond increases dramatically as the neutral substrate develops into the oxyanionic TS, resulting in TS stabilization of 5-7 kcal/mol, which is comparable to oxyanionic TS stabilization in serine hydrolases. We show that the rate of the exogenous (intermolecular) nucleophilic attack can be enhanced by 2000-fold by replacing the hydroxide nucleophile with peroxide, an alpha-nucleophile that is much more reactive than hydroxide. In the presence of peroxide, the rate saturates (k(cat)(max)) at 6 s(-1). This rate-ceiling appears to be dictated by the rate of the induced-fit conformational rearrangement leading to the active antibody-TS complex. The selective usage of negatively charged exogenous nucleophiles by the D-Abs led to the identification of a positively charged channel. Imprinted by the negatively-charged TS-analogue against which these antibodies were elicited, this channel presumably directs the nucleophile to the antibody-bound substrate. Our findings are discussed in comparison with serine esterases and, in particular, with cocaine esterase (cocE), which possesses a tyrosine based oxyanion hole.

Animals↗
PubMed1999

A case report of gastric carcinosarcoma with rhabdomyosarcomatous and neuroendocrinal differentiation.

We report herein an unusual gastric carcinosarcoma with rhabdomyosarcomatous and neuroendocrinal differentiation in a 63-year-old Japanese male. The tumor was a pedunculated large polypoid tumor (7 x 6.5 x 3.5 cm) located in the pylorus. Histologically, it invaded to the subserosa and was composed of both adenocarcinomatous and sarcomatous components. Adenocarcinomatous foci generally showed tubular to solid patterns and occupied the parts facing the gastric lumen, while the sarcomatous components showed a generally irregular and solid arrangement. There were transitions between the sarcomatous and carcinoma elements. In addition, carcinoma cells with a cord-like or trabecular arrangement similar to that seen in endocrine carcinoma expressed chromogranin A, and were mainly observed in an intermediate area between the adenocarcinomatous and sarcomatous foci. The sarcomatous areas were mainly composed of spindle cells and occasionally contained a sarcomatous component showing rhabdomyosarcomatous differentiation. This is an interesting case to consider how the variety of cell type appeared in such a type of tumor in the stomach.

Biomarkers, Tumor↗