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Plant root hair formation is initiated when specialized elongating root epidermis cells (trichoblasts) assemble distinct domains at the plasma membrane/cell wall cell periphery complexes facing the root surface. These localities show accumulation of expansin and progressively transform into tip-growing root hair apices. Experimentation showed that trichoblasts made devoid of microtubules (MTs) were unaffected in root hair formation, whereas those depleted of F-actin by the G-actin sequestering agent latrunculin B had their root hair formation blocked after the bulge formation stage. In accordance with this, MTs are naturally depleted from early outgrowing bulges in which dense F-actin meshworks accumulate. These F-actin caps remain associated with tips of emerging and growing root hairs. Constitutive expression of the GFP-mouse talin fusion protein in transgenic Arabidopsis,which visualizes all classes of F-actin in a noninvasive mode, allowed in vivoconfirmation of the presence of distinct F-actin meshworks within outgrowing bulges and at tips of young root hairs. Profilin accumulates, at both the protein and the mRNA levels, within F-actin-enriched bulges and at tips of emerging hairs. ER-based calreticulin and HDEL proteins also accumulate within outgrowing bulges and remain enriched at tips of emerging hairs. All this suggests that installation of the actin-based tip growth machinery takes place only after expansin-associated bulge formation and requires assembly of profilin-supported dynamic F-actin meshworks.

We performed an audit of 71 children with consecutive displaced, extension-type supracondylar fractures of the humerus over a period of 30 months. The fractures were classified according to the Wilkins modification of the Gartland system. There were 29 type IIA, 22 type IIB and 20 type III. We assessed the effectiveness of guidelines proposed after a previous four-year review of 83 supracondylar fractures. These recommended that: 1) an experienced surgeon should be responsible for the initial management; 2) closed or open reduction of type-IIB and type-III fractures must be supplemented by stabilisation with Kirschner (K-) wires; and 3) K-wires of adequate thickness (1.6 mm) must be used in a crossed configuration.The guidelines were followed in 52 of the 71 cases. When they were observed there were no reoperations and no malunion. In 19 children in whom they had not been observed more than one-third required further operation and six had a varus deformity. Failure to institute treatment according to the guidelines led to an unsatisfactory result in 11 patients. When they were followed the result of treatment was much better. We have devised a protocol for the management of these difficult injuries.

Objective:The purpose of this study was to compare outcomes after heart-lung or double-lung transplantation in patients undergoing transplantation because of end-stage suppurative lung disease. Methods:We reviewed our experience in patients with cystic fibrosis or bronchiectasis who had heart-lung or double-lung transplantation between January 1988 and September 1997. Twenty-three patients (14 male, 21 cystic fibrosis) had heart-lung transplantation and 24 patients (8 male, 19 cystic fibrosis) had double-lung transplantation. There were no statistically significant differences between the groups in age, weight, preoperative creatinine level, cytomegalovirus status, maintenance immunosuppression, or donor demographics. Patients received induction therapy with monoclonal (OKT3) or polyclonal (rabbit anti-thymocyte globulin) antibody. Results:Sixteen of 24 patients had double-lung transplantation after 1994 whereas 13 of 22 patients had heart-lung transplantation before 1991, allowing longer follow-up for the heart-lung group. Mean waiting times for transplantation were 270 ± 245 days (heart-lung) and 361 ± 229 days (double-lung; P= .20). The 1-, 3-, and 5-year actuarial survival figures were respectively 86%, 82%, and 65% (heart-lung) and 96%, 75%, and unavailable (double-lung; P= no significant difference). The 1-, 3-, and 5-year rates of freedom from obliterative bronchiolitis were respectively 77%, 61%, and 45% (heart-lung) and 86%, 78%, and unavailable (double-lung; P= no significant difference). Linearized overall infection rates (events/100 patient-days) were 2.05 ± 0.33 (heart-lung) and 2.34 ± 0.34 (double-lung; P= NS) at 3 months. Thirty-day survival was 100% (heart-lung) and 96% (double-lung). There were 7 late deaths among heart-lung recipients (3 obliterative bronchiolitis, 2 infection, 0 graft coronary artery disease, 2 other) whereas 2 late deaths related to obliterative bronchiolitis occurred in double-lung recipients. Graft coronary artery disease (all stenoses < 50%) affected 15% of heart-lung survivors, whereas 3 double-lung recipients (12.5%) required either bronchial dilatation or stenting. Conclusion:Heart-lung and double-lung transplantation provide similar palliation for patients with end-stage suppurative lung disease. Therefore double-lung transplantation should be the preferred operation for most patients with end-stage suppurative lung disease. (J Thorac Cardiovasc Surg 2000;119:466-76)

Young rapidly expanding leaves of a corn (Zea maysL.) plant are major photosynthate sinks. Recent evidence indicates that expansion of these young leaves may be severely restricted for a considerable time during the diurnal light period by low leaf water potential and/or low soil temperature. To better understand effects on photosynthesis of prolonged diurnal reduction in leaf expansion, net photosynthetic rate of lower mature leaves, which act as a major source of photosynthate for young expanding leaves, was monitored under environmental conditions shown to restrict the expansion of the young leaves. When leaf elongation was restricted by lowering root temperature from 27.5 C to 15.0 C, net photosynthetic rate of the source leaf was reduced 47% and soluble carbohydrate content of the sink leaf increased 45% at the end of a 7‐hour treatment period. Only about one‐third of this reduction in net photosynthesis was due to the concurrent decrease in leaf water potential. When leaf elongation was restricted by cooling the shoot apical meristem region from 27.5 C to 6.0 C, net photosynthetic rate of the source leaf decreased 24% and its soluble carbohydrate content increased 23% while the soluble carbohydrate content of the sink leaf increased 40% at the end of a 7‐hour treatment. These experiments support the hypothesis that environmental factors which limit leaf elongation may indirectly decrease photosynthetic potential of source leaves within the time limits of the diurnal stress cycle.

The installation and use of a 2,500‐W xenon long‐arc lamp is described. Xenon arc lamps emit a high intensity radiant flux with a visible spectrum similar to that of unfiltered sunlight. These qualities make it desirable for use in laboratory studies of plant growth. Little published information describing the use of xenon lamps in such application is available. Many technical problems may be encountered in the installation of long‐arc xenon lamps because of the lack of adequate installation instructions. The information presented here was developed over a long period of time and particular emphasis is on safety and cooling requirements. Although this lamp is expensive to install and operate, the spectral distribution of its radiation within the visible (400 to 700 nm) and near infrared wavebands is closer to that of natural sunlight than any other lamp presently available. Within the photosynthetically active waveband the conversion factor from radiant to quantum flux was determined to be 4.56 μ Einstein s−1m−2per Wm−2[Wm−2= Watts per m,2. Diagrams were prepared showing the angular distribution of radiation from this lamp.

The physiology of plant response to low soil temperatures is not well understood. Laboratory studies were conducted to examine the relative sensitivities of rates of leaf elongation, net photosynthesis, and transpiration and the leaf water potential of corn seedlings (Zea maysL. ‘Pride 5’) to decreasing temperature. These parameters were simultaneously monitored, as the soil temperature was decreased from 28 to 10 C at about 4 C increments. The different soil temperatures were imposed during a 10‐hour period on 14‐day‐old plants with seven exposed leaves growing at a 27.5 C air temperature, a 55% relative humidity, and a light intensity of 753 μE/m2/sec. Any decrease of the soil temperature below 28 C decreased the leaf elongation rate. This was attributed to restricted water uptake which lowered the plant water potential and to the temperature decrease of the shoot apical meristem region. Leaf elongation ceased at the plant water potential of —9 bars due to decline of leaf turgor pressure. Neither transpiration nor net photosynthesis was reduced significantly until the plant water potential reached —12 to —13 bars. Increases in both stomatal and internal resistances to CO2diffusion coincided with the decreased net photosynthesis at low plant water potentials. Suboptimal soil temperatures affect corn seedling growth primarily by decreasing leaf elongation.

The extent of anabolic steroid use among adolescent sports participants and nonparticipants in Nebraska schools was studied. The Nebraska Secondary School Survey administered in 1991 contained 19 new items designed to determine rates of use of anabolic steroids and to measure participation in school sports. Schools participating in the survey are part of the Toward a Drug Free Nebraska training project; when the 1991 survey was conducted, training did not address ergogenic drug use. The survey was administered on a voluntary and confidential basis to Nebraska students in grades 7 through 12. A total of 4722 students in 62 secondary schools were surveyed; 3183 (67.4%) identified themselves as participants in school-sponsored sports. Of all the respondents, 117 (2.5%) reported having used anabolic steroids in the preceding 30 days. Some 4.5% of all the male respondents were steroid users, versus 0.8% of all the females. Of the students who reported using anabolic steroids, 72.6% were sports participants. Steroid users, whether they participated in sports or not, were more likely to use alcohol, tobacco, and other drugs than were nonusers of steroids. Among sports participants and nonparticipants, anabolic steroid users were more likely than nonusers to report acting violently. Nebraska students (grades 7 through 12) who participated in school-sponsored sports were more likely than non-participants to use anabolic steroids. Steroid-using athletes were more likely to use alcohol, tobacco, and other drugs than athletes who did not use steroids.

Nine‐day‐old corn (Zea maysL.) plants were grown at soil water potentials of −035 and −2.50 bars for 6 days using an osmotic‐solution semipenneable‐membrane technique. Leaf elongation, total dry matter accumulation, transpiration, soluble carbohydrate concentrations, and leaf water potentials were measured daily. When the soil water potential was decreased from −035 to −2.50 bars, leaf elongation rates decreased 44% and soluble carbohydrate concentrations increased 42%, while rates of total dry matter accumulation and transpiration decreased 26 and 24%, respectively. The increase in the soluble carbohydrate concentration was inversely related to both the rates of leaf elongation and total dry matter accumulation. The plant maintains a positive carbon balance in the leaves partly in the form of an abundant supply of soluble carbohydrates during periods of mild water stress. The sensitivity of leaf elongation rate to mild water stress appears to be an important growth determining factor.

Two differing cementation methods were investigated in an in vitro simulation of hip arthroplasty.The bone-cement interface pressures were recorded during cement injection and stem insertion in matched pairs of fresh cadaveric femora. Reduced viscosity cement injected with a cement gun and proximal seal was compared with injection of high viscosity cement and finger-packing in each pair. The resultant shear strength of the bone-cement interface was measured by push-out tests. Results were analysed using the Wilcoxon ranked sum test for paired samples.The Exeter method of cementation produced significantly higher mean and maximum pressures above the bleeding pressure of femoral bone at all interface levels during cement injection. This was associated with significantly greater mean shear strengths. The authors conclude that the Exeter pressurization system for cementation overcomes the effect of femoral bone bleeding and improves the quality of the bone-cement interface. This may contribute to reduction in the incidence of loosening in cement hip arthroplasty.

The concept of appropriately combining two or more different polymers to obtain a new material system with the desirable features of its constituents is not new. Over the years, numerous systems based on the chemical combination of different monomers through random, block, and graft copolymerization methods have been developed with this goal in mind. For similar reasons, the coatings and rubber industries have long blended together different polymers, and particularly over the last decade the interest in polymer blend systems as a way to meet new market applications with minimum development cost has rapidly increased. This approach has not been without its difficulties and has not developed as rapidly as it might have, in part because most physical blends of different high molecular weight polymers prove to be immiscible. That is, when mixed together, the blend components are likely to separate into phases containing predominantly their own kind. This characteristic, combined with the often low physical attraction forces across the phase boundaries, usually causes immiscible blend systems to have poor mechanical properties. Despite this difficulty, a number of physical blend systems have been commercialized, and some of these are discussed later. However, there are ways around this problem of compatibility. Much research has shown that there are many truly miscible polymer pairs that can lead to significant opportunities for new products. Even for immiscible pairs, proper control of phase morphology during processing and/or the addition of "compatibilizing" agents can improve the interfacial situation mentioned above.

Two-dimensional representations of molecular structure may be generated from the three-dimensional coordinates by nonlinear mapping. These representations not only retain the look of familiar structural formulas but also incorporate the distance geometry information available in three-dimensional structures. The technique is shown to be trivial so long as the molecular structure is not essentially spherical and an objective test as to whether this is true is introduced, together with extensions for coping with such cases. The two-dimensional diagrams have great promise in handling molecular similarity and data searching with very large numbers of compounds since they permit the use of two-dimensional pattern recognition techniques.

The availability of two-dimensional representations of molecules which retain structural information permits the application of techniques from digital image processing to be applied to molecular similarity. Here three such approaches, invariant moments, radial integration and radial scanning, are investigated. They overcome the time consuming adjustment of the relative orientations of the molecules to be compared so as to optimize the similarity and can speed up the overall calculations by many orders of magnitude, hence offering a technique for dealing with the enormous numbers of compounds being generated by high throughput synthesis and combinatorial chemistry. These techniques are applied to the well-known set of steroids which are frequently used as a benchmark set for QSAR studies.

All the cells that compose the primary body of roots and shoots of plants derive from one or a few structural initial cells located within their apices. These cells are polyhedra, the number of whose wall faces (or sides) have increased during evolution. Mosses, algae, and leptosporangiate ferns may have initial cells with two, three or four faces, initial cells of eusporangiate ferns have five or six faces, while those of gymnosperms and angiosperms have eight faces. Seven-sided initial cells seem to be rare or absent. A scheme is proposed whereby the number of faces of an initial cell increases through an altered type of division and a suggestion is made as to how such changes may be fixed during ontogeny and, hence, how initial cell complexity becomes an aspect of plant phylogeny. In many "lower" plants, the orientation of cytokinesis in the structural initials is strictly regulated so that most, or all, of the faces of the mother cell wall pass into a daughter cell (merophyte) in a particular sequence. The same may also apply in "higher" plants, though from observational evidence this is less certain, but is nevertheless theoretically plausible. The division sequence may also be accompanied by a corresponding sequence of nuclear rotations which allows the chromosomes in the post-mitotic nucleus to retain the same positions, relative to the faces of the mother cell, that they had occupied prior to mitosis. Nuclear rotation may also facilitate conservative DNA segregation at mitosis in a structural initial, but, although there is some evidence for this, it is not an obligatory condition. Calculations are made, using three sets of conditions for division and DNA segregation, of the minimum angle of nuclear rotation necessary to accomplish one complete cycle of oriented divisions which involve all the faces of an initial (mother) cell, where the number of faces ranges from three to eight. The corresponding sequences of face involvements are also presented. Some sequences are unique to a given set of conditions. These can be compared with known sequences of divisions. In a case of a six-sided initial cell of a fern, the predicted and observed sequences correspond with semi-conservative DNA segregation and with a division rule whereby the oldest face of the mother cell wall is the one that will be donated to the next daughter merophyte. Many of the processes proposed that accompany and maintain initial cell structure and division are amenable to experimental testing. Copyright 1994, 1999 Academic Press

Cellophane wrapping of the hamster pancreas induces islet neogenesis. We have used the mRNA differential display technique to select for genes expressed during islet neogenesis but not in control pancreata. Ten candidate clones have been identified. Upon sequencing, 6 clones showed a high degree of homology to known genes, 1 showed some, and 3 showed no homology to genes of known sequence. Thus, mRNA differential display is a useful technique to identify genes induced during islet neogenesis, and in combination with screening hamster pancreatic cDNA libraries for full length clones, will enhance the likelihood of capturing the participants in this process.

A special co-ordinate system is developed for modelling the gravitropic bending of plant roots. It is based on the Local Theory of Curves in differential geometry and describes, in one dimension, growth events that may actually occur in two, or even three, dimensions. With knowledge of the spatial distributions of relative elemental growth rates (RELELs) for the upper and lower flanks of a gravistimulated root, and also their temporal dependencies, it is possible to compute the development of curvature along the root and hence describe the time-course of gravitropic bending. In addition, the RELEL distributions give information about the velocity field and the basipetal displacement of points along the root's surface. According to the Fundamental Theorem of Local Curve Theory, thexandyco-ordinates of the root in its bending plane are then determined from the associated values of local curvature and local velocity. With the aid of this model, possible mathematical growth functions that correspond to biological mechanisms involved in differential growth can be tested. Hence, the model can help not only to distinguish the role of various physiological or biophysical parameters in the bending process, but also to validate hypotheses that make assumptions concerning their relative importance. However, since the model is constructed at the level of the organ and treats the root as a fluid continuum, none of the parameters relate to cellular behaviour; the parameters must instead necessarily apply to properties that impinge on the behaviour of the external boundary of the root.

Abstract. Although putatively identified more than 10 years ago, thyroid hormone receptors in human tissues remain poorly characterized. As a first step towards understanding the mechanism of thyroid hormone action in man we have characterized T3binding sites in nuclei of the human lymphoblastoid line, IM-9 cells. In whole cell experiments at 37°C, nuclear binding of [125I]T3was saturable (Kd34 ± 6 pmol/l) and of finite capacity (≈ 350 sites/cell). The binding sites were extracted from a nuclear pellet by treatment with 0.4 mol/l KCl and sonication. Separation of bound from free [125I]T3in the extracts was achieved using the calcium phosphate matrix, hydroxyapatite at a concentration of 0.3 ml of a 150 g/l slurry. Rectilinear Scatchard plots were obtained only when the hydroxyapatite was washed with a buffer containing 0.5% Triton X-100. Under these conditions T3binding sites in the nuclear extracts were present at a concentration of 22.4 ± 8.6 fmol/mg protein and showed an affinity of (Kd, room temperature) 140 ± 10 pmol/l. The same assay system was used to determine the hierarchy of affinities for a range of natural and synthetic analogues. Calling T3100, the order of potencies observed was: Triac, 500; 3,5-diiodo-3′-isopropylthyronine, 89; T4, 32; 35-dimethyl-3′-isopropylthyronine, 2; 3,2-T2, 0.7, rT3, 0.4; 3′5′-T2, < 0.01. These results suggest that the T3binding sites present in human IM-9 lymphocyte nuclei and extracts thereof are thyroid hormone receptors. These cells may be a useful tool to increase our understanding of human T3receptors. The use of hydroxyapatite to separate bound from free hormone may be adapted for use with extracts of other tissues to characterize these receptors further.

Homozygous (di/di) Brattleboro rats have normal hypothalamic levels of oxytocin and neurophysin I, but undetectable levels of neurophysin II and arginine-vasopressin (AVP)1. This defect has been presumed to be at the genomic or transcriptional level, as AVP messenger is reported to be drastically reduced, if not absent, from the hypothalamus of Brattleboro rats2. Recent studies suggest de novo production of various neuropeptides in the mammalian gonad3–7, including AVP7. We report here the detection and localization of immunoreactive (ir) AVP in the luteal cells of adult homozygous Brattleboro rats, and the modulation of this ovarian ir-AVP by gonadotropins. These findings are thus consistent with a tissue-specific defect of AVP expression in the magnocellular neurones of the Brattleboro rat, and suggest that a comparable defect does not occur in the ovaries of such animals.

Topical antimicrobial solutions are used commonly for prevention or treatment of purulent otorrhea even though most solutions contain ototoxic agents. This study compares the cochlear and middle ear toxicity of cortisporin otic solution (COS), 0.3 gentamicin ophthalmic solution (GOS), benzalkonium chloride (0.026 and 0.05), and 1.0 Ofloxacin, a new quinolone antibiotic. Saline 0.9 was used as a control. The agent was instilled daily for 7 days into the bulla of juvenile guinea pigs. The animals were sacrificed on the 14th day. The organ of Corti was examined using surface preparation light microscopy and scanning electron microscopy. The tympanic membrane (TM) and adjacent middle ear mucosa were examined with light microscopy. The average cochlear hair cell damage was 66 for COS, 6.5 for GOS, and I for Ofloxacin, benzalkonium and saline. COS and benzalkonium 0.05 produced moderate mucosal thickening and inflammation. However, this was not statistically different from the mild mucosal thickening produced by saline, GOS, Ofloxacin and 0.026 benzalkonium. There was statistically significant mild to moderate thickening of the TM for all agents compared to the saline control.

Barlow JW, Curtis AJ, Raggatt LE, Loidl NM, Topliss DJ. Stockigt JR. Drug competition for intracellular triiodothyronine-binding sites. Eur J Endocrinol 1944;130:417–21. ISSN 0804–4643A variety of substances, including frusemide, non-esterified fatty acids (NEFAs) and non-steroidal antiinflammatory drugs (NSAIDs), can compete for triiodothyronine (T3)-binding sites in serum and at the cell surface. We examined the competitive potency of these agents at intracellular T3-binding sites in order to assess their potential to act as T3antagonists. Competition for [125I]T3binding was determined using hydroxyapatite separation in cytosols and nuclear extracts prepared from livers of Macaca fascicularis. The T3affinities were 15.8 ± 1.2 nmol/l in cytosol and 0.23 ± 0.02 nmol/l in nuclear extract. Does–response curves were analysed by a four-parameter sigmoid curve-fitting program to determine competitor potency. The nineteen agents tested included various NSAIDs, NEFAs, non-bile acid cholephils (NBACs), frusemide, amiodarone and the flavonoid EMD 21388. In nuclear extract the most active competitors were linoleic acid (8.5 μmol/l) and linolenic acid (7.8 μmol/l), Potencies of NSAIDs varied between 66 μmol/l (meclofenamic acid) and 525 μmol/l (diclofenac). In cytosol, NEFAs were less potent but NSAIDs were stronger competitors than in nuclear extract. Half-inhibitory potencies in cytosol were between 13.2 μmol/l (meclofenamic acid) and 63.1 μmol/l (flufenamic acid). The NBAC bromosulphthalein was one of the most potent inhibitors in both cytosol and nuclear extract. When expressed relative to T3, diclofenac was a more effective competitor in cytosol than it was in nuclear extract. Amiodarone and EMD 21388 were without effect both in cytosol and nuclear extract. Frusemide (759 μmol/l) was weakly active in cytosol only. The action of T3was assessed by measuring secretion of sex hormone-binding globulin (SHBG) in Hep-G2 cells. After 3 days with total T3(0.1 μmol/l), SHBG was 155 ± 15% of the control. Amiodarone (100 μmol/l) and meclofenamic acid (100 μmol/l) were cytotoxic. Bromosulphthalein (10 μmol/l), one of the most potent competitors at both the cytoplasmic and the nuclear level, did not influence the T3-induced rise in SHBG secretion. None of the drugs tested affected the magnitude of maximal induction of SHBG by T3. Substances that compete for serum and cell surface T3-binding sites are also weak competitors for intracellular T3-binding proteins, although the heirarchy of potency differs. Frusemide and diclofenac, with a greater relative potency for cytosolic binding than nuclear binding, may have potential use in investigating the function of cytosolic T3-binding. Amiodarone shows no binding activity and is not a hormone antagonist in primate hepatic tissue.John W Barlow, Ewen Downie Metabolic Unit, Alfred Hospital, Commercial Road, Melbourne, Victoria 3181, Australia

Barlow JW, Crowe TC, Cowen NL, Raggatt LE, Topliss DJ, Stockigt JR. Stimulation of sex hormone-binding globulin mRNA and attenuation of corticosteroid-binding globulin mRNA by triiodothyronine in human hepatoma cells. Eur J Endocrinol 1994;130:166–70. ISSN 0804–4643We examined the time course and dose response of the triiodothyronine (T3) effect on mRNAs for sex hormone-binding globulin (SHBG) and corticosteroid-binding globulin (CBG) in cells of the human hepatoma line HepG2. After 7 h of exposure to a saturating dose of T3, SHBG mRNA was unchanged but increased to 1.5±0.1 times the unstimulated control at 22 h. Maximal stimulation (2.3±0.6) was observed at 2–3 days. Corticosteroid-binding globulin mRNA was unchanged for 22 h after exposure to T3but diminished thereafter to 64% by day 3. At 3–4 days of exposure, the changes in both SHBG mRNA and CBG mRNA were dose-responsive to the T3concentration. For both mRNAs, half-maximal response occurred between 10 and 20 pmol/l bioavailable T3. Cortisol-binding proteins secreted by HepG2 cells after 3 days in culture also were T3dose-responsive. No re-uptake of secreted CBG by the cells was observed, suggesting that the T3effect on CBG secretion occurs during production of the mature protein. These data suggest that T3stimulates the expression of the SHBG gene and attenuates the expression of the CBG gene. The effects of T3on these genes are consistent with the increase in circulating SHBG and decrease in circulating CBG observed in hyperthyroidism. The HepG2 cells may be a useful human cell line in which to study the diversity of the molecular mechanisms of T3action.JW Barlow, Ewen Downie Metabolic Unit, Alfred Hospital, Commercial Rd. Melbourne, Victoria 3181, Australia

Juge-Aubry CE, Liang H, Lang J, Barlow JW, Burger AG. Synthesis and characterization of anti-idiotypic anti-thyroxine antibodies. Eur J Endocrinol 1994;130:107–12. ISSN 0804–4643We injected rabbits with purified monoclonal murine immunoglobulin (IgG1) or polyclonal anti-thyroxine antibodies (anti-T4) and polyclonal anti-triiodothyroacetic acid (anti-Triac) antibodies to stimulate the production of anti-idiotypic antibodies. Purified immunoglobulins from all five rabbits immunized with monoclonal primary antibodies were able to inhibit the interaction between [125I]T4and the primary antibody. The preimmune sera were inactive. This effect was not due to endogenous T4contamination or contamination with the injected primary antibody. Half-maximal inhibition of binding of primary antibody with anti-idiotype was between 1.6 and 30 μg of total immunoglobulins. Addition of normal mouse IgG1 did not alter the inhibitory effect of the anti-idiotypic antibody. suggesting that this effect is specific. These anti-idiotypic antibodies reacted differently with different polyclonal antibodies, reflecting the heterogeneous nature of polyclonal antibody populations. Polyclonal antibodies were less effective in stimulating anti-idiotypic antibody production. One polyclonal anti-T4and one anti-Triac antibody produced weak anti-idiotypic antibody that had to be used at a concentration of > 600 μg of total immunoglobulins to be inhibitory. Both inhibited the binding of T4to the monoclonal anti-T4antibody. However, they were ineffective in inhibiting the function of their own antigen, the polyclonal anti-T4or anti-Triac antibody. We tested the most potent anti-idiotypic antibodies for their ability to compete with T4for other T4-binding proteins. Specific inhibition of T4binding to thyroid-binding globulin was observed with half-maximal effect at approximately 450 μg of total IgG. The antibody was negative when tested against Transthyretin, rat liver deiodinase type I, triiodothyronine cell uptake and liver cytoplasmic triiodothyronine binding. In conclusion, the technique described herein allows production of anti-idiotypic anti-T4, which can be useful in the characterization of the range of iodothyronine-binding sites involved in thyroid hormone action.AG Burger, Unité de la Thyroïde, Hôpital Cantonal Universitaire, 1211 Genève 4, Switzerland

We evaluated the effect of particle size on MR contrast-enhancing properties of arabinogalactan-coated superparamagnetic iron oxide (AG-SPIO) in tumor-bearing rats.

In an attempt to further elucidate the molecular mechanisms that determine the loss of dough strength associated with heat stress of growing wheat, the roles of heat-shock proteins (HSP) and heat-shock elements upstream of glutenin genes were investigated. A range of genotypes differed in the extent of synthesis of high molecular weight glutenin subunits (HMW-GS) and HSP during heat stress. The concentration of HSP 70 remaining in mature grain increased as a result of a few days' heat stress of wheat plants. The amount of HSP 70 in mature grain samples from heat-stressed plants of 45 genotypes was not strongly correlated with loss of dough strength. There was much less evidence for this mechanism than for other molecular hypotheses from the literature, particularly, changes in glutenin-to-gliadin ratio, size distribution of the glutenin polymer, and the involvement of HSP and chaperones during grain-protein synthesis. HSP 70 was purified from heat-stressed grain, and was added to (or incorporated into) dough in the direct-drive mixograph. The HSP behaved similarly to several other hydrophilic proteins when added at a level of 2 mg/2 g of flour. It showed no dramatic effects on dough properties that could constitute a major explanation for the dough-weakening effects of heat stress, even though the level of addition was well above the maximum levels that might be encountered in field-grown, mature grain. Furthermore, sequencing of the genes (upstream of the coding region) for HMW-GS failed to show the presence of heat-shock promoters, even for genotypes that differed considerably in their reactions to heat stress. The findings simplify the range of possibilities that cause heat-related loss of dough strength, focusing attention on the degree of polymerization of the glutenin chains, and on the roles of HSP and chaperones in the developing grain.

A retrospective review is presented of 44 consecutive patients requiring hospitalization for epistaxis at a tertiary care center. The study had the following objectives: 1.to identify predictors of surgical treatment, and 2.to compare the effectiveness of different surgical treatments. Length of stay, complications, and cost analysis are also presented. Eighteen patients were successfully treated nonsurgically, whereas 26 patients received surgical treatment. Posterior epistaxis (P<0.05) and an admission hematocrit less than 38% (P<0.05) were significant predictors of surgical treatment. The rebleed rate after first surgical therapy was 33% for embolization, 33% for endoscopic cautery, and 20% for ligation. Since embolization, ligation, and endoscopic cautery may have nearly equivalent failure rates, other factors, such as cost and institutional expertise, should guide the selection of surgical treatment.

Success and Failure in Arms Control Negotiations, April Carter, Oxford University Press for SIPRI, 1989. £27.50Europe in Transition: Politics and Nuclear Security. Edited by Vilho Harle and Pekka Sivonen. London: Pinter Publishers, 1989. Pp. vii & 184; index. ISBN 0-86187-812-4. £30 hb.The Gulf and International Security: The 1980s and Beyond. Edited by M.E. Ahrari. London: Macmillan, 1989. 200 pp. Bibliography. Index. £35.Rocking the Boat: New Zealand, the United States and the Nuclear-Free Zone Controversy in the 1980s. Paul Landais-Stamp and PAUL Rogers. Oxford: Berg Publishers, 1989. 185 pp. Index. £16.50.The Militarization of South African Politics, Kenneth W. Grundy; I.B. Tauris and Co.: London, 1986. £27.50Conventional Deterrence into the 1990s. Edited by Thomas Boyd-Carpenter. (foreword by Rt Hon. Michael Hesltine MP). London: Macmillan/ RUSI, 1989, 189pp., £29.50 hardback.Fighter for Peace: Philip Noel-Baker 1889-1982. David J. Whittaker. William Sessions: York, 1989. 401 pp. ISBN 1 85072 056 8. £10.

AbstractThis paper presents the development to date of Selective Laser Sintering (SLS) technologies for production of cermet composite turbine sealing components, the particular application being an abrasive blade tip. The component chosen for the application is an integral part of the low pressure turbine in a. IHPTET (Integrated High Performance Turbine Engine Technology) demonstrator engine. Both indirect and direct SLS techniques are being developed. Initial trials and process development involved the use of fugitive polymeric binders. Sequential refinements were performed to develop a binderless direct SLS process. Results from mechanical testing indicate that acceptable microstructure and properties are attainable by SLS with substantial cost savings as compared to the currently employed production method. This is the first instance of direct Solid Freeform Fabrication (SIT) method applied to a functional component.

The major immediate-early (IE) gene region of human cytomegalovirus (HCMV) encodes several proteins as a result of differential RNA splicing events. By expression vector cloning of HCMV IE mRNA, we isolated and characterized a cDNA for a novel splice variant from the major IE gene region. The RNA product is a derivative of the IE55 mRNA and contains an additional splice from nucleotides 170,635 to 170,307 in the IE2 gene region (UL122), resulting in a 1.4-kb mRNA. The predicted open reading frame codes for a 164-amino-acid protein with a calculated molecular mass of 18 kDa (IE18). Mung bean nuclease analysis and PCR were used to characterize expression of IE18 mRNA in HCMV-infected cells. While the 1.4-kb mRNA was detected in infected human fibroblasts in the presence of a protein synthesis inhibitor, it was not detectable during a normal infection. However, the 1.4-kb mRNA was readily detected in infected human monocyte-derived macrophages at IE times. These results suggest that the novel IE18 mRNA exhibits cell type-specific expression indicating differential regulation of the major IE gene region in different permissive cell types.

Indirect immunofluorescence using a-tubulin antibodies applied to sections of maize roots prepared using low melting point wax was found to give excellent visualisation of both cortical and endoplasmic microtubule (MT) arrays. This allows, for the first time, these arrays to be investigated in cells of the different tissues at various stages of their growth and development. Many cells in the zone between the meristem and the cell elongation region develop a highly ordered transversal bundling of cortical MTs, which we suggest is related to vacuolation of the cytoplasm and which may also be indispensable for the ensuing rapid cell elongation. On the other hand, there are subtle differences between the cells of the individual tissues regarding the arrangement of their cortical MTs in this zone. The possible physiological significance of these tissue-specific MT arrays is discussed. Endoplasmic MTs were seen to encircle and to connect the nucleus with the cortical MT arrays in both dividing and elongating cells. Even the G1 phase nuclei of the slowly dividing cells of the quiescent centre were encircled by endoplasmic MTs. The continuity of the two MT systems may provide the cell with an important signalling system whereby mechanical and physiological information is relayed from the exterior of the cell to the nucleus.

trans activation of promoters by viral regulatory proteins provides a useful tool to study coordinate control of gene expression. Immediate-early (IE) regions 1 and 2 of human cytomegalovirus (CMV) code for a series of proteins that originate from differentially spliced mRNAs. These IE proteins are proposed to regulate the temporal expression of the viral genome. To examine the structure and function of the IE proteins, we used linker insertion mutagenesis of the IE gene region as well as cDNA expression vector cloning of the abundant IE mRNAs. We showed that IE1 and IE2 proteins of CMV exhibit promoter-specific differences in their modes of action by either trans activating early and IE promoters or repressing the major IE promoter (MIEP). Transient cotransfection experiments with permissive human cells revealed a synergistic interaction between the 72- and the 86-kilodalton (kDa) IE proteins in trans activating an early promoter. In addition, transfection studies revealed that the 72-kDa protein was capable of trans activating the MIEP. In contrast, the 86-kDa protein specifically repressed the MIEP and this repression was suppressed by the 72-kDa protein. Furthermore, observations based on the primary sequence structure revealed a modular arrangement of putative regulatory motifs that could either potentiate or repress gene expression. These modular domains are either shared or unique among the IE proteins. From these data, we propose a model for IE protein function in the coordinate control of CMV gene expression.

The purpose of this study was to determine whether changes in arterial plasma potassium concentration [K+]a affect expired ventilation (VE) in euoxia, hypoxia and hyperoxia during rest and light exercise in humans. Three periods of ventilatory measurements were undertaken in eight healthy subjects at rest and in seven other subjects during cycle ergometry (70 W). The first period of measurement was before the ingestion of 64 mmol of potassium chloride (KCl), the second 20 min after ingestion of KCl when [K+]a levels were elevated, and the third 3 h after the ingestion of KCl when [K+]a had returned substantially to normal. During each period, end‐tidal PO2 was cycled between euoxia, hypoxia and hyperoxia, whilst the end‐tidal PCO2 was maintained constant. The acute ventilatory response to hypoxia (AHVR) was calculated as the difference in VE during hypoxia and hyperoxia within each period of measurement. Oral KCl produced a 1.3 +/‐ 0.2 mM (mean +/‐ S.E.M.) increase in [K+]a at rest and a 0.8 +/‐ 0.2 mM increase during exercise. There was no significant difference in ventilation during euoxia between the three periods of measurement at rest or during exercise. There was a significant increase in AHVR with the rise in [K+]a of 21 min‐1 mM‐1 at rest (arterial PO2 during hypoxia ca 57 Torr) and 10 l min‐1 mM‐1 during exercise (arterial PO2 during hypoxia ca 52 Torr). There was a significant difference in the absolute increase in AHVR with [K+]a between rest and exercise, but this difference was not significant if the increase in AHVR with [K+]a was expressed as a percentage of the initial AHVR. We conclude that changes in [K+]a of the order of 1 mM have little effect on euoxic ventilation at rest or during light exercise in humans. We also conclude that [K+]a changes of this order increase AHVR at rest and during light exercise and that increases in [K+]a contribute to the increase in AHVR with exercise in humans.

Direct contact of the radiating perinuclear microtubules (MTs) with the nuclear envelope was visualized with an immunogold technique using specific monoclonal tubulin antibody. The possibility that these perinuclear MT arrays are involved in establishing and maintaining nuclear organization during the interphase of cycling cells in maize root meristems was tested using taxol, a MT‐stabilizing agent. Taxol not only stabilized all MTs against the action of the MT‐disrupters colchicine and oryzalin but also prevented these agents from their usual induction of nuclear enlargement and decondensation of nuclear chromatin. On the contrary, nuclear size decreased and the chromatin became more compact in mitotically cycling cells of the taxol‐treated root apices. Moreover, taxol prevented the stimulation, by colchicine and oryzalin, of the onset of the S phase in cells of the quiescent centre and proximal root meristem. Exposure of maize roots to taxol strongly decreased final cell volumes, suggesting that the more condensed nuclear chromatin is less efficient in genome expression and that this accounts for the restriction of cellular growth. All these findings support the hypothesis that MT arrays, radiating from the nuclear surface, are an essential part of an integrated plant ‘cell body’ consisting of nucleus and the MT cytoskeleton, and that they regulate, perhaps via their impact on chromatin condensation and activity, progress through the plant cell cycle.

The development of the decidua in rodents is associated with the production of multinucleate and giant cells (Fig. 1A). In the rat, binucleate cells appear throughout the secondary or antimesometrial zone of the decidua by the eighth day of pregnancy (Krehbiel, 1937), while in the mouse this region is characterized by large bi-, tri-, or tetranucleate cells (Snell & Stevens, 1966). All decidual cells may eventually enlarge, containing nuclei of a size consistent with a DNA content of four, eight and possibly even higher multiples of the haploid complement (Sachs & Shelesnyak, 1955). In the white rat spectrophotometric determination of DNA levels in decidual cells indicates that by the tenth day of gestation ploidy levels have reached 16C–32C, with maximal levels of 64 times the haploid DNA content (Zybina & Grishchenko, 1972). The mechanism of nuclear enlargement in decidual tissue is as yet unknown.

We have used a DNA-cellulose competition assay to investigate the binding of thyroid hormone receptors to fragments of the mouse glandular kallikrein genes and the human and rat GH genes. Nuclear extracts from human lymphoblastoid IM-9 cells were incubated with [125I]tri-iodothyronine ([125I]T3) and DNA-cellulose. The ability of cloned gene fragments to compete for radiolabelled receptors bound to DNA-cellulose was compared with that of DNA from pBR322. As previously observed, a 900 bp fragment from the human GH gene showed preferential binding to the thyroid hormone receptor. High-affinity binding was observed with a synthetic fragment of the rat GH gene encompassing positions − 163 to − 192 but not with a similar fragment from positions −224 to −192. Preferential binding was also observed with fragments of the mouse glandular kallikrein gene, mGK-6. Binding to the entire gene and fragments containing 2300 and 776 bp of the promoter region was identical. Detectable but reduced binding was seen with a shorter fragment. These results suggest that the T3receptor binds to multiple sites within the first 776 bp of the mGK-6 gene promoter. Potential thyroid hormone response elements can be identified within this region of the gene. In contrast, the kallikrein gene mGK-3, which shows a different response to thyroid hormone from that of mGK-6, showed no significant binding in the comparable promoter region.

The thyroid hormone analogue, SKF-94901 exhibits greater thyromimetic activity in the liver than in the heart. This difference in activity may reflect heterogeneity in the affinity of SKF-94901 for different forms of the T3receptor. A difference in extranuclear transport of the analogue could also account for the different response of these two tissues. To distinguish between these possibilities we have examined the binding of SKF-94901 to membrane, cytosolic and nuclear preparations from liver and heart of the primate, Macaca fascicularis. Uptake of SKF-94901 into H4liver cells was low. Binding of [125I]T3to cell membrane preparations (Kd≈3 μmol/l), and to nuclear extracts (Kd≈0.2 nmol/l was displaceable by SKF-94901 with a potency 2-5% that of T3in each case. No significant difference was observed between liver and heart for SKF-94901 binding to membranes or nuclear extract. With cytosol, [125I]T3binding was identical in heart (Kd, 22.7±10.4 nmol/l) and liver tissue (Kd, 30.3±11.1 nmol/l). In liver, and in cardiac cytosol after preliminary washing to remove serum, iodothyronine potency was in the order T3> T4> rT3. The ratio of SKF-94901 to T3concentrations which gave 50% displacement was 15.9±6.8 in the liver; and 152.3±89.1 in the heart (p<0.05). The selective tissue activity of SKF-94901 may be related to a reduced affinity of the analogue for the cytosolic binding proteins in the heart, rather than a difference in affinity for various forms of the T3receptor.

1. We studied a brominated thyroid hormone analogue, SKF L-94901, which has the potential to lower serum cholesterol without adverse cardiovascular effects. This compound is about 50% as active as tri-iodothyronine (T3) in liver nuclear receptor binding in vivo but only 1% as active in vitro and has nearly 200 times more enzyme-inducing activity in liver than in heart. Our aim was to examine the interaction of SKF L-94901 with [125I]T3 binding to the intact nuclei in whole cells, isolated nuclei and nuclear extracts of human HeLa cells and to investigate the binding of this compound to human serum. 2. Relative to thyroxine (T4), the affinity of this compound for T4-binding globulin was 0.0035%, for transthyretin 1.66% and for albumin 1.26%. Low affinity for serum proteins, with a relatively high circulating free fraction, could explain why SKF L-94901 is more potent in vivo than in vitro. 3. Human HeLa cell nuclei, isolated after whole-cell incubations, bound [125I]T3 with high affinity (Kd = 78 ± 8 pmol/l, mean ± sem), which was displaceable by T3 analogues in the order Triac {[4-(4-hydroxy-3-iodophenoxy)-3,5-di-iodophenyl]acetic acid} > T3 > T4 ≫ reverse T3. Similar high-affinity (Kd = 58 ± 6 pmol/l, mean ± sem) and identical specificity was observed in high-salt (0.4 mol/l KCl) nuclear extracts. In nuclei of whole cells incubated with [125I]T3 and SKF L-94901, the analogue was 0.8% as potent as T3, whereas in experiments with nuclear extract, the analogue was 7.7% as potent as T3. Results from incubation of T3 with isolated nuclei were virtually identical to those obtained with nuclear extracts. 4. These results suggest an extranuclear component may be involved in restricting access of SKF L-94901 to the nucleus. Whether such mechanisms account for observed differences in its effects on different tissues with reduced influence of SKF L-94901 on cardiac tissue remains to be established. 5. We conclude that SKF L-94901 is weakly bound in serum and shows less potent competition for T3 nuclear binding after incubation of whole cells than after incubation with nuclear extracts or isolated nuclei. This compound may allow further analysis of intracellular mechanisms of thyroid hormone transport and action.

Summary Optical density profiles of Feulgen-stained nuclei ofBryonia dioica at different stages of the mitotic cycle were determined. Nuclei in the G2 phase have a greater fraction of dense chromatin than nuclei in G1 phase. However, nuclei at the end of the S phase have dispersed chromatin of minimal density. Thus, chromatin density oscillates during the mitotic cycle of this species, consequently the progressive increase in density previously recorded throughout the intermitotic period of two other species (onion and mouse) cannot be a general rule.