Phytoextraction of arsenic from soil by Leersia oryzoides.

The potential of Leersia oryzoides (rice-cut grass) to remediate arsenic-contaminated soil was studied in greenhouse pot experiments. Leersia oryzoides grown in soil amended with arsenic to a concentration of 110 mg kg(-1), extracted up to 305 mg kg(-1) and 272 mg kg(-1) arsenic into its shoots and roots, respectively, giving a shoot:root quotient of 1.12 and phytoextraction coefficients up to 2.8. Plants in the arsenic-amended soil showed visible signs of stress in the first 8 wk of growth, but then recovered. Based on the 132 plants that were grown in a surface area of approximately 180 cm2, the calculated total arsenic taken up by shoots is 120, 130, and 130 g ha(-1) at 6, 10, and 16 wk, respectively, suggesting that additional arsenic could be removed by periodic mowing over a growing season. Extraction with a mixture of nitric acid and hydrogen peroxide indicated that the available arsenic was constant after the first 6 wk. Uptake is comparable to that reported for duckweed (Lemna gibba L.) and overlaps the low end of the values reported for Chinese brake fern (Pteris Vittata L.)

Vibration and spinal lengthening in simulated vehicle driving.

There is active interest in the relationship between back pain and driving. The availability of a precision stadiometer enabled experiments to be done to explore the effects of simulated driving on the change in spinal length, the hypothesis being that the spinal load would cause a shrinking in the length of the spine. The experiments demonstrated that, when exposed to a combination of vertical and horizontal vibration at 4 Hz the spinal length increased for all eight subjects, whilst under no vibration conditions there was a decrease in the average length. At 6 and 8 Hz there was no statistically significant change in length. The results suggest that there is an unloading of the spine when subjects under simulated driving conditions are exposed to vibrations in two directions at a frequency close to the spine's natural frequency.

Head posture and loading of the cervical spine.

Calculations by Colombini et al. (Ergonomics of Working Postures. Taylor & Francis, London, 1985) showed that a line of gaze below the horizontal would load the cervical spine more than a horizontal gaze. Precision stadiometer tests were run, using seven subjects, to measure the effects on spinal length of different angles of gaze. After 1 h exposure whilst sitting in a controlled posture, there were significant differences in the shrinkage of the spine between the horizontal gaze and the 20 and 40 angles below the horizontal. The increased spinal loading demonstrated by the increase in spinal shrinkage calls into question the recommendations for angle of gaze recommended in textbooks.

Heterogeneity in the bioactivity of LH secreted by peripubertal rats.

Treatment of immature rats with 5 iu equine chorionic gonadotrophin (eCG) on day 25 typically stimulates a preovulatory surge of LH on day 27 and ovulation on day 28. In rats weighing > 60 g at the time of treatment, an LH surge and ovulation occurred in 75% of the animals but, in rats weighing < 60 g, only 13% ovulated even though 69% showed an LH surge. Previous findings have shown that exogenous LH can stimulate ovulation in the rats < 60 g, indicating that the anovulation was not due to ovarian immaturity, but rather to an abnormal form of LH. Thus, it was important to determine whether the bioactivity of LH released at the time of the surge differs in rats < 60 g compared with rats > 60 g. Experiments showed that LH from both groups of eCG-treated animals were equipotent in stimulating testosterone production from incubated Leydig cells and progesterone production from cultured granulosa cells. Similarly the surge of progesterone in vivo, which occurs co-incident with the LH surge, was of similar magnitude in both groups of animals. Since prostaglandin synthesis increases at the time of ovulation and is also stimulated by LH, it was investigated whether the activity of ovarian phospholipase A2, the rate limiting enzyme in prostaglandin synthesis, and ovarian prostaglandin E2 concentrations differed in the animals > 60 g and < 60 g. Phospholipase A2 activities were similar in both groups of animals at the time of the LH surge, as were the prostaglandin E2 concentrations. However, in all animals that ovulated (15/20 in rats > 60 g and 2/15 in rats < 60 g), there was a threefold increase in ovarian prostaglandin E2 concentrations. The results show that, in underweight animals, the bioactivity of LH, in terms of its ability to stimulate steroidogenesis and phospholipase A2 activity, is similar to that released by animals > 60 g; however, the LH produced by the underweight animals fails to induce ovulation by failing to increase, either directly or indirectly, prostaglandin E2 production. Comparison of the profiles of plasma LH collected at the time of the LH surge on an anionic ion exchange column indicates that the LH from rats < 60 g possesses significantly less of the neutral or basic glycoform of LH than that from rats > 60 g. This finding provides a further index that the biopotency of LH produced by underweight animals is different from that of rats > 60 g.

Dispersion-managed solitons for terrestrial transmission.

We describe a scheme involving the insertion of segments of dispersion-compensating fiber, pumped to yield Raman gain, at one or more intermediate points within each 80-km-or-greater span between amplifier huts. With dispersion-managed solitons, the scheme is expected to allow for error-free, many-channel wavelength-division multiplexing, with high spectral efficiency, over transmission distances of many thousands of kilometers.

Regulation of epidermal growth factor receptor by androgens in human endometrial cells in culture.

Women with polycystic ovaries (PCO) have a thicker endometrium than women with normal ovaries. This cannot be due to unopposed oestrogen, as it occurs in ovulatory cycles. Androgens may be involved, as these are raised in women with PCO. The effects of steroids are partly mediated by growth factors and their receptors. The aim of this study was to investigate the effect of androgens on epidermal growth factor (EGF) receptor in human endometrium. Endometrium was enzymatically dispersed and glands and stromal cells separated. Cells were incubated in Ham's F10 medium supplemented with 5% charcoal-stripped fetal calf serum and either androgens or vehicle. Specific binding of [125I]-labelled EGF was measured. Testosterone and dihydrotestosterone (DHT) (10 micromol/l) increased EGF receptor concentration (control 100 +/- 9%, testosterone 196 +/- 23% control; control 100 +/- 1%, DHT 244 +/- 6% control) but did not alter receptor affinity. The effect of testosterone was inhibited by the anti-androgen hydroxyflutamide, but not by the antioestrogen ICI182780 nor the aromatase inhibitor 4-hydroxyandrostenedione. EGF receptor levels were increased by androstenediol (control 100 +/- 2%, androstenediol 120 +/- 10% control) but not by androstanediol, dehydroepiandrosterone (DHA), DHA sulphate or androstenedione. Testosterone and DHT increased EGF receptor concentrations in glandular epithelium (control 100 +/- 24%, testosterone 147 +/- 5%, DHT 185 +/- 30% control). These data suggest that androgens may have an effect on the endometrium via an increase in EGF receptor concentrations.

Regulation of epidermal growth factor receptor synthesis by ovarian steroids in human endometrial cells in culture.

The aim of this study was to investigate the effect of oestradiol and progesterone on epidermal growth factor (EGF) binding in human endometrial glands and stromal cells in culture. Monolayers of isolated glands or stromal cells were cultured for 6 days in the presence or absence of steroids which were replenished daily. Binding of 125I-labelled EGF was measured in the presence and absence of unlabelled EGF. Over a 6 day period, oestradiol caused a dose-dependent increase in the number of EGF receptors in stromal cells, with a maximum effect of 150% control at a concentration of 10 nmol l-1. The effect of progesterone was also dose dependent and reached a maximum of 170% control at 100 nmol progesterone l-1. Oestradiol and progesterone in combination caused a greater increase in EGF receptor concentration than did either steroid alone (control, 100 +/- 11%; oestradiol, 144 +/- 11% control; progesterone, 200 +/- 20% control; oestradiol and progesterone, 288 +/- 6% control). Steroid treatment did not alter the affinity of the receptor for EGF. The stage of the cycle of the tissue did not affect the response to steroids. The effect of oestradiol was inhibited by the anti-oestrogen ICI182780, and that of progesterone by the anti-progestin RU486. In endometrial glands, neither oestradiol nor progesterone affected the number of EGF receptors, but the two steroids in combination induced an increase of 140 +/- 23% control where control was 100 +/- 15%. These data demonstrate that oestradiol and progesterone increase the number of EGF receptors in vitro, and suggest that EGF is involved in mediating the actions of these steroids on the processes of proliferation and differentiation in the human endometrium.

An inhibitor of leukocyte elastase prevents immune complex-mediated hemorrhage in the rat lung.

The typical reverse passive Arthus reaction (RPA) was attained in rats by the instillation of a rabbit antiovalbumin serum into the lungs and intravenous injection of ovalbumin. Instillation of antiserum alone caused accumulation of polymorphonuclear leukocytes (PMN) and increased vascular permeability, but did not cause hemorrhage. However, when an intravenous injection of ovalbumin was also given, the vascular permeability of the lungs increased dramatically and PMN, as well as hemoglobin, were measurable in the lung lavage fluids by 4 hr after initiation of the reaction. Various proteinase inhibitors were instilled into the lungs after the initial stages of the RPA had developed, specifically to investigate their effect on the development of the hemorrhage, which we chose to monitor as an indicator of severe vascular damage. A cephalosporin-based beta-lactam, L-658,758, which is a time-dependent inhibitor of human and rat PMN elastase, effectively prevented the lung hemorrhage associated with the RPA reaction (ED50 = 2 x 55 micrograms doses/animal when instilled at 1.5 and 2.5 hr after initiating the RPA). The PMN elastase inhibitor, methoxysuccinyl-alanyl-alanyl-prolyl-valine-chloromethylketone, also inhibited hemorrhage in this model. Compounds of the same chemical class as these elastase inhibitors, but having no activity against PMN elastase in vitro, did not affect the hemorrhage associated with the RPA. Several specific inhibitors of proteinases other than PMN elastase (e.g., pepstatin and methoxysuccinyl-prolyl-glycyl-alanyl-lysine-chloromethylketone) were found to have little effect on the hemorrhage associated with the RPA reaction.(ABSTRACT TRUNCATED AT 250 WORDS)

The art of negotiation. Getting what you want out of a managed care contract.

As managed care takes a firm hold in the marketplace, healthcare organizations are hurrying to align. While some executives are skilled negotiators, well versed in the complexities of managed care contracting, others are new to the process. Those seeking direction in the art of negotiation can benefit by reviewing the principles that follow. While basic, they will help you make the most of the negotiation process.

Inhibitor of phospholipase A2 blocks eicosanoid and platelet activating factor biosynthesis and has topical anti-inflammatory activity.

The effect of a phospholipase A2 (PLA2) inhibitor on leukotriene, prostaglandin and platelet activating factor (PAF) biosynthesis in isolated cells and in vivo was determined. BMS-181162, [4(3'-carboxyphenyl)-3,7-dimethyl-9(2",6",6"-trimethyl-1"- cyclohexenyl)2Z,4E,6E,8E-nonatetraenoic acid], reversibly inhibited the 14-kdalton PLA2 purified from human synovial fluid with an IC50 of 8 microns. In A23187-stimulated human polymorphonuclear leukocytes (PMNs), BMS-181162 blocked arachidonic acid release with an IC50 of 10 microns. Leukotriene B4 and PAF biosynthesis in these cells was also inhibited. In a phorbol ester-induced chronic mouse skin inflammation model, topically applied BMS-181162 markedly lowered the tissue levels of leukotriene B4 and prostaglandin E2 and dose-dependently inhibited leukocyte infiltration (ED50 = 180 micrograms per ear). BMS-181162 is an inhibitor of PLA2 and may prove to be a useful tool in the delineation of the role of PLA2 in the inflammatory process.

The epidermal growth factor receptor in the human endometrial adenocarcinoma cell line HEC-1-B.

The binding characteristics and steroidal regulation of the EGF receptor were investigated in the human endometrial adenocarcinoma cell line HEC-1-B. The cell line was shown to possess a single, high affinity binding site for epidermal growth factor receptor (EGF) with a Kd of 3.09 +/- 1.39 nM (mean +/- SD, n = 6) and binding of 845 +/- 311 fmol/mg protein (mean +/- SD, n = 6). The protein kinase C activator, phorbol 12-myristate, 13-acetate (PMA) increased the Kd of the EGF receptor in a dose dependent manner (PMA: 0, 1, 10, 100 nM; Kd: 4.1, 5, 10, 50 nM, respectively). The effect of PMA (10 nM) was overcome by preincubating the cells with the protein kinase C inhibitor staurosporine (1 microM) prior to the addition of PMA. The effect of the ovarian steroids oestradiol and progresterone on EGF receptor accumulation was studied by pretreating the cells for 6 days with oestradiol or progesterone in phenol red free DMEM:F12, 1:1 supplemented with 5% charcoal stripped fetal calf serum. Both steroids were shown to increase EGF receptor number with a maximum 5- and 7-fold increase in the presence of 1 nM oestradiol or 1 microM progresterone, respectively. The study demonstrates the presence of a high affinity binding site for EGF in HEC-1-B cells which is regulated by oestradiol and progresterone.

Characterization of epidermal growth factor receptor in human endometrial cells in culture.

The aim of the study was to determine the binding characteristics of the epidermal growth factor (EGF) receptor in isolated human endometrial glands and stromal cells in culture. Stromal cells and glands were obtained from endometrial tissue by collagenase dispersion followed by sieve filtration. They were plated into 24-well multiwell plates in Ham's F10 medium supplemented with 5% fetal calf serum and used at 70-80% confluence. Scatchard analysis revealed a single class of high-affinity binding sites in both cell types with apparent dissociation constants of 1.17 +/- 0.6 (n = 15) and 1.20 +/- 0.3 (n = 8) nmol 1-1 for stromal cells and glands, respectively. The concentration of receptors was higher in stromal cells than in glands, 719 +/- 377 (n = 16) and 310 +/- 177 (n = 8) fmol mg-1 protein, respectively. Epidermal growth factor labelled with 125I was displaced from the receptor by EGF and transforming growth factor alpha, but not insulin, insulin-like growth factor, fibroblast growth factor, or platelet-derived growth factor. Binding was shown to be dependent on time and temperature. Downregulation of the receptor was demonstrated by preincubating cells with 5 nmol EGF I-1, which reduced receptor concentrations by 75%. 12-O-Tetradecanoylphorbol-13-acetate decreased the affinity of the receptor for EGF changing the dissociation constant from 1.8 to 3.9 nmol l-1. A suitable system for investigating the regulation of this receptor in human endometrium was established.

In vivo and in vitro effects of gamma-linolenic acid and eicosapentaenoic acid on prostaglandin production and arachidonic acid uptake by human endometrium.

This study examines the effect of a 6 month dietary supplement of either gamma-linolenic acid (GLA) or eicosapentaenoic acid (EPA) on the synthesis of prostaglandins E2 and F2 alpha by the endometrium of women with regular menstrual cycles. Samples of endometrium, obtained pre- and post-treatment, were incubated in vitro for 2 h and the prostaglandins E2 and F2 alpha released into the medium measured by radioimmunoassay. The ability of the tissue to take up 14C-arachidonic acid before and after treatment was also examined. Both GLA and EPA caused a marked decrease in the synthesis of prostaglandins E2 and F2 alpha (P < 0.001) but under the experimental conditions used, there was no consistent effect on arachidonic acid uptake. Body mass index, serum testosterone, fasting insulin and serum sex hormone-binding globulin (SHBG) concentrations did not change during the 6 month treatment period. An effect of GLA and EPA on arachidonic acid uptake into endometrial tissue explants was demonstrated in vitro. In the presence of both GLA and EPA, uptake into phospholipids (particularly phosphatidylcholine) decreased while uptake into triglycerides increased. Free 14C-arachidonic acid levels (that which could not be removed from the tissue by washing) also increased. Suppression of endometrial prostaglandin E2 and F2 alpha synthesis following GLA or EPA supplementation can be explained as direct competition between these fatty acids and arachidonic acid (the precursor of 2-series prostaglandins) for incorporation into membrane phospholipids. The amount of arachidonic acid available for 2-series prostaglandin synthesis will therefore be reduced. However, other mechanisms may exist which need to be investigated.(ABSTRACT TRUNCATED AT 250 WORDS)

Hormonal control of ovarian phospholipase A2 activity in rats.

The ovulatory effect of LH is mediated by prostaglandins, the synthesis of which involves prostaglandin synthetase and phospholipase A2 (PLA2). It is known that the activity of the former is regulated by LH in the ovary and the objective of this study was to establish the presence of PLA2 in the rat ovary and to determine whether LH has a role in regulating its activity. We demonstrated the presence of a calcium-dependent PLA2 in rat ovaries and shown that, in adult rats, the activity of this enzyme rises significantly on the evening of pro-oestrus (at the expected time of the preovulatory LH surge) and remains high over the evening hours, declining by the next morning. Furthermore, pregnant mares' serum gonadotrophin (PMSG), which when injected into 28-day-old rats induces an LH surge 54 h later, caused at the same time, a rise in ovarian PLA2 activity. Administration of 5 micrograms oestradiol benzoate S.C. to 25-day-old rats stimulated ovarian PLA2 activity 54 h later, at the time of the oestrogen-induced LH surge. Human chorionic gonadotrophin (hCG) had no effect on circulating concentrations of LH, FSH or oestradiol but stimulated ovarian PLA2 activity 2 h later. Gonadotrophin-releasing hormone (GnRH) given to 25-day-old rats (either untreated or primed with 0.5 mg oestradiol benzoate) had no effect on ovarian PLA2 activity but the resulting LH surge may have been too transient.(ABSTRACT TRUNCATED AT 250 WORDS)