Stress stimulates production of catecholamines in rat adipocytes.

The sympathoadrenal system is the main source of catecholamines (CAs) in adipose tissues and therefore plays the key role in the regulation of adipose tissue metabolism. We recently reported existence of an alternative CA-producing system directly in adipose tissue cells, and here we investigated effect of various stressors-physical (cold) and emotional stress (immobilization) on dynamics of this system. Acute or chronic cold exposure increased intracellular norepinephrine (NE) and epinephrine (EPI) concentration in isolated rat mesenteric adipocytes. Gene expression of CA biosynthetic enzymes did not change in adipocytes but was increased in stromal vascular fraction (SVF) after 28 day cold. Exposure of rats to a single IMO stress caused increases in NE and EPI levels, and also gene expression of CA biosynthetic enzymes in adipocytes. In SVF changes were similar but more pronounced. Animals adapted to a long-term cold exposure (28 days, 4°C) did not show those responses found after a single IMO stress either in adipocytes or SVF. Our data indicate that gene machinery accommodated in adipocytes, which is able to synthesize NE and EPI de novo, is significantly activated by stress. Cold-adapted animals keep their adaptation even after an exposure to a novel stressor. These findings suggest the functionality of CAs produced endogenously in adipocytes. Taken together, the newly discovered CA synthesizing system in adipocytes is activated in stress situations and might significantly contribute to regulation of lipolysis and other metabolic or thermogenetic processes.

A simple, small and low cost permanent magnet design to produce homogeneous magnetic fields.

A new portable, pocket-size NMR probe based on a novel permanent magnet arrangement is presented. It is based on a Halbach-type magnet design which mimics the field of a spherical dipole by using cylindrical bar and ring magnets. The magnet system is made up of only three individual magnets, and most field calculations and optimisations can be performed analytically. A prototype system has been built using a set of small, off the shelf commercially available permanent magnets. Proton linewidths of 50 ppm FWHM could be achieved at a field strength of 1T. Calculations show that with custom-sized permanent magnets, linewidths of less than 1 ppm can be achieved over sample volumes of up to 1 mm3, which would in theory enable chemical shift resolved proton spectroscopy on mass-limited samples. But even with the achieved linewidth of 50 ppm, this can be a useful portable sensor for small amounts of liquid samples with restricted molecular mobility, like gels, polymers or high viscosity liquids.

A mobile one-sided NMR sensor with a homogeneous magnetic field: the NMR-MOLE.

A new portable NMR sensor with a novel one-sided access magnet design, termed NMR-MOLE (MObile Lateral Explorer), has been characterised in terms of sensitivity and depth penetration. The magnet has been designed to be portable and create a volume with a relatively homogeneous magnetic field, 15,000 ppm over a region from 4 to 16 mm away from the probe, with maximum sensitivity at a depth of 10 mm. The proton NMR frequency is 3.3 MHz. We have demonstrated that with this approach a highly sensitive, portable, unilateral NMR sensor can be built. Such a design is especially suited for the characterisation of liquids in situations where unilateral or portable access is required.

[Experimental testing of a new coil design for endoluminal MRI applied to the pig stomach]. / Experimentelle Erprobung eines neuen Spulendesigns zur endoluminalen MRT am Beispiel des Schweinemagens.

PURPOSE: Experimental feasibility study of a new MR-Coil concept for enhanced visualization of the gastric wall. MATERIAL AND METHODS: The newly developed single-loop receiver coil for endoluminal imaging (Fraunhofer Institute, St. Ingbert, Germany) was evaluated in 4 explanted pig stomachs in a 1.5T MR unit (Siemens Symphony, Erlangen, Germany) with T1 w and T2 w MR sequences in three planes. The new coil consists of a foldable and self-expanding single loop coil (receiver coil) of a shape memory metal (nitinol). It was covered with a biocompatible material (silicone) to prevent direct contact of the wire with stomach tissue. The coil assumes a circular configuration with a diameter of 8 cm because of its memory metal properties. The flexible characteristics of the material used allow the passage through the instrument channel (13 mm diameter) of a specially designed MR-compatible endoscope. The purpose of our study was to assess feasibility of the coil design as a first step in developing a new endoluminal MRI-concept. Additionally the number and signal intensity of visible gastric wall layers were evaluated and findings were correlated with histopathological results of a pig stomach. RESULTS: The new coil concept was a feasible system in all 4 cases and showed good image quality for analysis. On T1 w images, 3 layers were visible in all cases, and on T2 w images 4 different gastric wall layers were seen in 2 cases. Due to histopathological correlation, the different gastric wall layers were identified as follows: mucosa, submucosa and muscularis propria if three layers were depicted; in cases of 4 visible wall layers, serosa and subserosa could be detected additionally. For each gastric wall layer, a distinct signal intensity was found. CONCLUSION: The new MR coil concept for endoluminal imaging proved to be a feasible technique. Good differentiation of gastric wall layers in the pig stomach could be demonstrated. We have shown that endoscopic MR-imaging with our new coil concept is a valuable technique for the visualization of gastric wall layers. Due to this fact, follow-up studies including assessing safety aspects are necessary to finally conduct an experimental-clinical study on in-vivo human gastric specimens to detect tumor growth and morphology within the gastric wall. Endoscopic MRI may have the potential in the future to overcome today's limitations of diagnostic imaging in gastric cancer.

Effects of adrenergic agonists and antagonists on the numbers of synaptic ribbons in the rat pineal gland.

In the pineal gland numbers of synaptic ribbons (SR) undergo day/night changes which parallel the rhythm of melatonin synthesis. Since pineal biosynthetic activity is controlled by activation of adrenoreceptors, we investigated the effects of adrenergic agonists and antagonists on pineal synaptic ribbon numbers and N-acetyltransferase (NAT) activity, the key enzyme of melatonin synthesis in rats. In vivo application of the beta-adrenergic antagonist propranolol decreased melatonin synthesis when given during the dark phase but did not affect SR numbers. Treatment during daytime with the beta-adrenergic agonist isoproterenol increased pineal NAT activity whereas SR numbers did not change. Norepinephrine stimulated NAT activity in vitro in a dose-dependent manner, but did not elevate SR numbers. Incubation with an analog of the second messenger cyclic adenosine monophosphate increased both NAT activity and SR numbers. These results suggest that the beta-adrenergic system does not play a decisive role in the regulation of the nocturnal increase in SR numbers observed in the rat pineal gland.

Lack of binding of gestodene to estrogen receptor in human breast cancer tissue.

Competition studies with progesterone and estradiol receptors of human myometrial tissue as well as of mammary cancer tissue showed that gestodene bound with high affinity to the progesterone receptor, as did other synthetic and natural progestogens. However, gestodene did not bind to the estradiol receptor. The relative binding affinities of all tested synthetic and natural ligands showed no organ-specific differences and no differences between neoplastically transformed and normal tissues.

The impact of lipid distribution, composition and mobility on xylem water refilling of the resurrection plant Myrothamnus flabellifolia.

• Lipids play a crucial role in the maintenance of the structural and functional integrity of the water-conducting elements and cells of the resurrection plant Myrothamnus flabellifolia during complete dehydration. • Lipid composition, mobility and distribution within the internodal and nodal xylem regions (including short shoots and leaves) were investigated in the presence and absence of water by using various nuclear magnetic resonance (NMR) spectroscopy and imaging techniques differing greatly in the level of spatial resolution and acquisition of lipid parameters. • Significant findings include: a discontinuity in the branch xylem between an inner zone where no water moves and an outer zone where the water moves; the blocking of water movement in the inner zone by lipids that are not dispersed by water, and the facilitation of water advance in the xylem elements and pits of the outer zone by water-dispersed lipids; the relative impermeability of leaf trace xylem to the rehydrating water and, hence, the relative hydraulic isolation of the leaves. • These results elucidated part of the strategy used by the resurrection plant to cope with extreme drought and to minimize transpirational water loss upon hydration.

Fabrication of homogeneously cross-linked, functional alginate microcapsules validated by NMR-, CLSM- and AFM-imaging.

Cross-linked alginate microcapsules of sufficient mechanical strength can immunoisolate cells for the long-term treatment of hormone and other deficiency diseases in human beings. However, gelation of alginate by external Ba(2+) (or other divalent cations) produces non-homogeneous cross-linking of the polymeric mannuronic (M) and guluronic (G) acid chains. The stability of such microcapsules is rather limited. Here, we show that homogeneous cross-linking can be achieved by injecting BaCl(2) crystals into alginate droplets before they come into contact with external BaCl(2). The high effectiveness of this crystal gun method is demonstrated by confocal laser scanning microscopy and by advanced nuclear magnetic resonance imaging. Both techniques gave clear-cut evidence that homogeneous cross-linkage throughout the microcapsule is only obtained with simultaneous internal and external gelation. Atomic force microscopy showed a very smooth surface topography for microcapsules made by the crystal gun method, provided that excess Ba(2+) ions were removed immediately after gelation. In vitro experiments showed greatly suppressed swelling for crystal gun microcapsules. Even alginate extracted from Lessonia nigrescens (highly biocompatible) yielded microcapsules with long-term mechanical stability not hitherto possible. Encapsulation of rat islets, human monoclonal antibodies secreting hybridoma cells and murine mesenchymal stem cells transfected with cDNA encoding for bone morphogenetic protein (BMP-4) revealed that injection of BaCl(2) crystals has no adverse side effects on cell viability and function. However, the release of low-molecular weight factors (such as insulin) may be delayed when using alginate concentrations in the usual range.

A comparison of cytoplasmic and nuclear estradiol and progesterone receptors in human fallopian tube and endometrial tissue.

Quantitative and qualitative aspects of the in vitro binding of 3H-estradiol and 3H-progesterone to receptor components from human endometrium and fallopian tube cytoplasmic and nuclear fractions were studied. The steroid binding macromolecules formed in vitro could be extracted from nuclei by 0.4 M KCl and detected by glycerol gradient centrifugation. Both estradiol- and progesterone-binding compounds formed only one peak (under high ionic strength conditions) with a sedimentation coefficient of about 4-5 S. The number of cytoplasmic and nuclear binding sites for both estradiol and R5020 varied dramatically throughout the menstrual cycle: the estradiol and progesterone receptor concentrations were highest during the proliferative phase and were very significantly lower in the second half of the menstrual cycle. Furthermore, measurement of both receptors in the cytosol revealed differences among the anatomic segments of the fallopian tube. The highest estradiol and progesterone binding could be detected in the ampullary region; significantly lower levels of estradiol and progesterone receptors were seen in the infundibulum and the isthmus.

One millisecond of light suffices to suppress nighttime pineal melatonin synthesis in rats.

The effect of a single high-intensity light pulse with a duration of 1 ms on nighttime pineal activity of male Sprague-Dawley rats was investigated. 10 minutes after light exposure pineal N-actyltransferase activity and melatonin content were significantly reduced. These results show that the rat pineal is capable of responding to very short light flashes of high intensity.

Steroid hormone receptors in human melanoma.

Human melanomas were investigated for the presence of high-affinity estrogen-, gestagen-, and glucocorticoid-binding proteins. A statistically significant difference was found for mean estrogen receptor (ER) concentrations in melanomas of male versus female origin: female origin 37.6 (0-107) fmol/mg protein, male origin 3.9 (0-8.3) fmol/mg protein. No significant difference between sexes was found for gestragen receptors: 41.5 (0-194) fmol/mg protein for melanomas of female origin versus 99 (0-362) fmol/mg protein for male. Sucrose density gradient analyses revealed specific binding for both receptor types in the 4-5 S region as well as in the 8 S region. The binding affinities were in the same order of magnitude as reported for receptors found in typical steroid target organs. No significant difference in receptor values depending on sex was found for the glucocorticoid receptor: 19.2 (0-43) fmol/mg protein.

Characterisation of fluid flow through porous media using three-dimensional microimaging and pulsed gradient stimulated echo NMR.

Pulsed gradient stimulated echo (PGSTE) and microimaging nuclear magnetic resonance (NMR) are used to probe correlations between structure and flow in the void space of a model porous system formed from a packing of 1-mm diameter glass spheres. The pulsed gradient stimulated echo data determine the average propagator and permit the dispersion of the flow to be studied as a function of delay time. Microimaging yields structural information and, specifically, a reduced radial distribution function (rdf) for the structure of the void space. Transition to fully developed dispersive flow is shown to occur on a scale size for which no further correlations in the structure of the void space are observed.

Gestodene: a novel synthetic progestin--characterization of binding to receptor and serum proteins.

Gestodene, 17 alpha-ethinyl-13-ethyl-17 beta-hydroxy-4,15-gonadien-3-one, is a new orally active progestational agent, which is available for clinical use in oral contraceptives. The aim of the present study is to make a broad characterization of gestodene at the receptor level and to discuss the results in comparison to those of established progestogens. Kinetic studies of 3H-gestodene uptake show a rapid increase in the amount of specific binding during the first three hours. After saturation, the amount of specifically bound 3H-gestodene remained almost constant up to 24 hours at 4 degrees C. The dissociation of 3H-gestodene from the cytoplasmic myometrial progestone receptor, measured by displacement of labeled steroid with dextran-coated charcoal treatment at 4 degrees C at various times, showed a biphasic or two-component first order dissociation curve. As anticipated, sucrose gradient centrifugation analysis of the 3H-gestodene-labeled cytosol of human myometrial tissue showed that the gestodene binding components sedimented in the 4S and 8S region. A 200-fold molar excess of nonradioactive gestodene reduced only the 8S binding of 3H-gestodene. 4S binding of 3H-gestodene was not reduced, which indicate the existence of a second high capacity binding component. In biological test systems, such as the Clauberg test or Kaufmann test, gestodene has proved to be a very effective progestogen. Among nortestosterone derivatives it is one of the most potent and resembles progesterone biologically in its progestogenic effects. This biologically identical gestagenic activity of gestodene and progesterone is reflected by a very similar behavior in vitro in terms of binding to progesterone receptors of human uterus cytosol. Furthermore, competitive studies indicated that gestodene like other synthetic progestagens also displays some affinity for androgen and glucocorticoid receptors but no measurable affinity for the estrogen receptor. Remarkable is the high binding affinity of gestodene to the binding sites of the mineralocorticoid receptor of rat kidney with a RBA value of 350% compared to aldosterone.

3H-ZK 98,734, a new 11 beta-aryl substituted antigestagen: binding characteristics to receptor and serum proteins.

Recently, in the laboratories of Schering in Germany a competitive progesterone antagonist, ZK 98,734, was synthetized, which is characterized by a similar antigestagenic activity as RU 38,486, synthezised by Roussel-Uclaf in France, as assessed by inhibition of nidation tests in rats and guinea pigs. However, this compound has a substantially lower antiglucocorticoid activity measured in cell culture systems than RU 38,486. The purpose of this study was to present a comparison of biochemical and physical properties of the complexes formed by the human uterine progesterone receptor with 3H-ZK 98,734 on one hand and with other well-established progestins on the other hand. ZK 98,734 competed in the same order of magnitude as progesterone or RU 38,486 for the 3H-R5020 binding site of progestin receptor, whereas R5020, Org 2058 or progesterone were unable to compete against 3H-ZK 98,734. This apparent contradiction could be explained by means of FPLC-chromatography and sucrose density centrifugation technique. FPLC-chromatography with an anion exchange column (Mono Q, Pharmacia, Uppsala, Sweden) showed that 3H-ZK 98,734 forms at least two stable complexes with uterine cytosol, on one hand with serum albumin, which presents almost 90% of bound radioactivity, and on the other hand with the two native progestin receptor forms, corresponding to 4S and 8S receptor forms in sucrose density gradient analysis. Competition experiments in liver cytosol of adrenalectomized rats with increasing concentrations of unlabeled ligands other than dexamethasone showed that ZK 98,734, RU 38,486 and cortisol displaced 3H-dexamethasone efficiently from the binding sites in the cytosol. Furthermore, results concerning the specificity of 3H-cortisol binding to serum proteins in diluted pregnant serum demonstrated that ZK 98,734 did not compete with 3H-cortisol for serum binding.

p-Chlorophenylalanine treatment depresses the number of synaptic ribbon profiles in the rat pineal gland, but does not abolish their day-night rhythm.

It is largely unknown as to how the day/night rhythm of pineal synaptic ribbon number is regulated. Transcriptional events related to the nocturnal formation of new synaptic ribbons occur early in the morning, when pineal serotonin levels begin to increase. The present study was carried out in order to elucidate as to how altered serotonin levels affect the day/night changes in the number of synaptic ribbon profiles. To this end, male Sprague-Dawley rats received a single dose of p-chlorophenylalanine (pCPA, 300 mg/kg body weight, 72 hours before sacrifice), which depresses tryptophan hydroxylase activity and hence pineal serotonin levels. Control animals received saline injections. Experimental and control animals were killed in the middle of the light period and in the middle of the dark period, respectively. The pineal glands were removed and bisected. One half was used for electron microscopic quantification of synaptic ribbon profile numbers, and the other half for determination of several biochemical parameters (see below). pCPA decreased pineal serotonin levels to c. 30% of the controls and synaptic ribbon profile numbers by c. 30%, both at day and night. The day/night rhythm of the two parameters did not appear to be affected. The rate-limiting enzyme of melatonin synthesis, serotonin N-acetyltransferase, which is only measurable at night, and pineal melatonin levels were not affected at night. The intermediary product of melatonin formation, N-acetylserotonin, was significantly depressed at night. It is concluded that serotonin plays a more important modulatory role on pineal synaptic ribbons than does melatonin.(ABSTRACT TRUNCATED AT 250 WORDS)

Modeling categorical variables by logistic regression.

OBJECTIVE: To demonstrate the use of logistic regression in health care research. METHOD: Forward and backward stepwise logistic regression algorithms were systematically applied to a real-world data set comprising 301 cancer patients and a set of explanatory variables. RESULTS: Four variables were identified as effective predictors of pain reporting by cancer patients during chemotherapy: fatigue, depression, severity of colds or viral infections, and insomnia. The 4-predictor model was validated by (a) significance tests of regression coefficients at p<0.05, (b) significant improvement of this model over competing models, and (c) goodness of fit indices. CONCLUSIONS: Logistic regression is useful for health-related research in which outcomes of interest are often categorical.

Faculty perceptions of teaching on television: one school's experience.

Videoteleconferencing (or teaching on television) represents a means of growing importance for distant learners to gain greater access to nursing education. Research has identified a number of key issues for nurse educators to consider related to videoteleconferencing: teaching/evaluation strategies, faculty workload, rewards and incentives, and support structures. The authors conducted an evaluation survey using a case study approach aimed at describing the perceptions of a convenience sample of faculty members (n = 17) regarding their recent television experiences. The survey, conducted by means of a mailed questionnaire, examined perceptions centering on sources of support, reception site logistics, rewards teaching strategies, and future directions. Key findings included: overall, respondents perceived television teaching positively; reception site, administrative support, and peer support were important to faculty; additional preparation time was required for television teaching; teaching on television required changes in style and pedagogical strategies; and student-teacher interactions were affected by the medium. Findings have implications for the implementation of videoteleconferencing operations, recruitment of faculty for television teaching, and evaluation of videoteleconferencing operations.

Towards a medically approved technology for alginate-based microcapsules allowing long-term immunoisolated transplantation.

The concept of encapsulated-cell therapy is very appealing, but in practice a great deal of technology and know-how is needed for the production of long-term functional transplants. Alginate is one of the most promising biomaterials for immunoisolation of allogeneic and xenogeneic cells and tissues (such as Langerhans islets). Although great advances in alginate-based cell encapsulation have been reported, several improvements need to be made before routine clinical applications can be considered. Among these is the production of purified alginates with consistently high transplantation-grade quality. This depends to a great extent on the purity of the input algal source as well as on the development of alginate extraction and purification processes that can be validated. A key engineering challenge in designing immunoisolating alginate-based microcapsules is that of maintaining unimpeded exchange of nutrients, oxygen and therapeutic factors (released by the encapsulated cells), while simultaneously avoiding swelling and subsequent rupture of the microcapsules. This requires the development of efficient, validated and well-documented technology for cross-linking alginates with divalent cations. Clinical applications also require validated technology for long-term cryopreservation of encapsulated cells to maintaining a product inventory in order to meet end-user demands. As shown here these demands could be met by the development of novel, validated technologies for production of transplantation-grade alginate and microcapsule engineering and storage. The advances in alginate-based therapy are demonstrated by transplantation of encapsulated rat and human islet grafts that functioned properly for about 1 year in diabetic mice.