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We describe briefly the properties of the recently completed Southern African Large Telescope (SALT), along with its first light imager SALTICAM. Using this instrument, we present 4.3 hr of high speed unfiltered photometric observations of the eclipsing polar SDSSJ015543.40+002807.2 with time resolution as short as 112 ms, the highest quality observations of this kind of any polar to date. The system was observed during its high luminosity state. Two accreting poles are clearly seen in the eclipse light curve. The binary system parameters have been constrained: the white dwarf mass is at the low end of the range expected for cataclysmic variables. Correlations between the positions of the accretion regions on or near the surface of the white dwarf and the binary system parameters were established. The sizes of the accretion regions and their relative movement from eclipse to eclipse were estimated: they are typically 4-7 deg depending on the mass of the white dwarf. The potential of these observations will only fully be realised when low state data of the same kind are obtained and the contact phases of the eclipse of the white dwarf are measured.

The IL-1R antagonist protein (IRAP) is a competitive inhibitor of IL-1, which is predominantly synthesized by monocytes. We show that this molecule is also expressed in human synovial fibroblasts and dermal fibroblasts (CRL 1445). IRAP mRNA was regulated in a time- and dose-dependent manner by IL-1 alpha, TNF-alpha, LPS, and PMA. Maximal induction of IRAP mRNA was observed between 8 and 16 h after stimulation with IL-1 alpha (1 U/ml), TNF-alpha (10 U/ml), LPS (50 ng/ml), and PMA (10 ng/ml). Their relative efficacy was as follows: PMA > LPS > IL-1 alpha > TNF-alpha. Potentiation was observed when fibroblasts were treated with IL-1 alpha plus basic fibroblast growth factor and IL-1 alpha plus platelet-derived growth factor-BB homodimer. Although LPS and PMA were the best inducers of IRAP mRNA, quantitation of the IRAP protein revealed that its synthesis and release were differentially regulated. Immunoprecipitation and SDS-PAGE of culture supernatant from LPS-treated cells and cell lysates of fibroblasts treated with LPS or PMA showed a single IRAP band with a molecular mass of approximately 22 kDa. Very little IRAP was detected in culture supernatants of cells treated with PMA. Quantitation of IRAP revealed that LPS induced the synthesis of secreted IRAP that was released, whereas the majority of the protein induced by PMA remained cell-associated. Reverse transcriptase-polymerase chain reaction amplification demonstrated that although LPS and PMA induced both transcripts, LPS preferentially induced secreted IRAP, whereas PMA differentially induced intracellular IRAP mRNA. Fibroblasts synthesize at least two different forms of IRAP depending on the inducing signal, and may regulate the inflammatory response by dampening the proinflammatory effects of IL-1 via a negative feedback mechanism with IRAP. The relative importance of fibroblast sIRAP vs intracellular IRAP in regulating the inflammatory response by the connective tissue remains to be determined.

The cytokine interleukin-1 (IL-1) has been reported to inhibit the hypothalamic-pituitary-gonadal axis, both through actions in brain and at the gonadal level. Recently, high affinity binding sites for 125I-recombinant human IL-1 alpha have been identified in the mouse testis with characteristics similar to those of type I IL-1 receptors on T lymphocytes and fibroblasts. The present study employed in situ hybridization histochemistry with 35S-labeled antisense cRNA probes derived from a murine type I IL-1 receptor cDNA to identify type I IL-1 receptor mRNA in the mouse testis. An intense signal was observed over interstitial cells, and over the cytoplasm of the epithelium of epididymal ducts, most prominently in the head region. The signal over seminiferous tubules, and over sperm cells within tubules and epididymal ducts, was comparable to background. This distribution of type I IL-1 receptor mRNA was similar to that recently reported for 125(I)I-IL-1-alpha binding sites, and supports evidence implicating IL-1 as a direct regulator of gonadal function.

Genetically modified domestic animals have many potential applications ranging from basic research to production agriculture. One of the goals in transgenic animal production schemes is to reliably predict the expression pattern of the foreign gene. Establishing a method to screen genetically modified embryos for transgene expression before transfer to surrogates may improve the likelihood of producing offspring with the desired expression pattern. In order to determine how transgene expression may be regulated in the early embryo, we generated porcine embryos from two distinct genetically modified cell lines by using the nuclear transfer (NT) technique. Both cell lines expressed the enhanced green fluorescent protein (eGFP); the first was a fibroblast cell line derived from the skin of a newborn pig that expressed eGFP, whereas the second was a fetal derived fibroblast cell line into which the eGFP gene was introduced by a retroviral vector. The reconstructed embryos were activated by electrical pulses and cultured in NCSU23. Although the in vitro developmental ability of each group of NT embryos was not different, the eGFP expression pattern was different. All embryos produced from the transduced fetal cell line fluoresced, but only 26% of the embryos generated from the newborn cell line fluoresced, and among those that did express eGFP, more than half had a mosaic expression pattern. This was unexpected because the fetal cell line was not clonally selected, and each cell had potentially different sites of integration. Embryos generated from the newborn cell line were surgically transferred to five surrogate gilts. One gilt delivered four female piglets, all of which expressed eGFP, and all had microsatellites identical to the donor. Here we demonstrate that transgene expression in all the blastomeres of an NT embryo is not uniform. In addition, transgene expression in a genetically manipulated embryo may not be an accurate indicator of expression in the resulting offspring.

We have employed the baculovirus expression system for the production of insect cell membranes having GABA/benzo–diazepine binding sites. Three recombinant baculoviruses each harboring a different GABAA receptor cDNA were introduced into insect cells by simultaneous infection. Infected cells expressed GABA responsive Cl- channels and benzodiazepine binding sites with the same pharmacological specificity as animal cells expressing these receptor subunits.

1. We discovered a novel gamma-aminobutyric acidA (GABA(A)) receptor ligand displaying seemingly opposite functionalities, depending on the alpha isoform of the alpha(x)beta2gamma2 subtypes. PNU-107484A enhanced GABA-induced Cl- currents in the alpha1beta2gamma2 subtype, but inhibited the currents in the alpha3beta2gamma2 and alpha6beta2gamma2 subtypes, and its half-maximal concentrations in the subtypes were 3.1 +/- 0.5, 4.2 +/- 1, and 3.5 +/- 0.2 microM, respectively, without showing much dependency on alpha isoforms. 2. In the alpha1beta2 subtype, the drug at concentrations up to 40 microM showed no effect on GABA-induced Cl- currents, suggesting the requirement of the gamma subunit for its action. 3. PNU-107484A behaved like a positive allosteric modulator of the alpha1beta2gamma2 subtype with its binding site distinct from those for benzodiazepines, barbiturates and neurosteroids. With the alpha3beta2gamma2 subtype, the drug behaved like a non-competitive inhibitor of GABA, thus blocking Cl- currents by GABA alone or in the presence of pentobarbitone and neurosteroids. 4. It appears that PNU-107484A is a unique GABA(A) receptor ligand with alpha isoform-dependent functionalities, which may provide a basis for development of alpha isoform-selective ligands, and it could be useful as a probe to investigate the physiological roles of the various alpha isoform subtypes.

Relationships among U.S. college students' (N = 618) attitudes toward rape myths and their sex role orientation, affective responses to sexuality, sex role egalitarianism, and attitudes toward violence against women were investigated. Results indicated that men were more tolerant of rape, more likely to attribute blame for rape to the victim, and less negative in their views of rapists than women were. In addition, for men, but not for women, masculinity and femininity were predictive of rape attitudes and attributions of blame to rape victims. Positive attitudes toward sexuality were predictive of intolerance of rape for the total sample and for men, but not for women, and were predictive of perceptions of women as innocent victims of rape for both the total sample and the sexes separately. Attitudes toward pornography were unrelated to attitudes toward rape. Acceptance of violence against women and a lack of sexual egalitarianism were predictive of acceptance of rape myths. Androgynous, masculine, and feminine individuals were less tolerant of rape than undifferentiated persons were.

We characterized modulation of the gamma-aminobutyric acid (GABA)-evoked responses of the diazepam-insensitive alpha 4 beta 2 gamma2 and alpha 6 beta 2 gamma 2 recombinant GABAA receptors. The partial agonist bretazenil potentiated the responses of both receptors with similar dose dependence but with a higher maximal enhancement at the alpha 4 beta 2 gamma 2 receptor. The bretazenil-induced potentiation was reduced by the benzodiazepine antagonist flumazenil. At a high concentration (10 microM), flumazenil was a weak potentiator of the GABA response. The partial agonist imidazenil was inactive. The imidazobenzodiazepine inverse agonist Ro 15-4513, which is known to bind with high affinity to the alpha 6 beta 2 gamma 2 receptor, potentiated the GABA responses of the alpha 4 beta 2 gamma 2 and alpha 6 beta 2 gamma 2 receptor subtypes with similar dose dependence over the concentration range of 0.1-10 microM. Methyl-6, 7-dimethoxy-4-ethyl-beta-carboline, a beta-carboline inverse agonist, had a similar potentiating effect when tested at a concentration of 10 microM. The alpha 4 beta 2 gamma 2 and alpha 6 beta 2 gamma 2 receptor-mediated currents had equal sensitivities to furosemide and Zn2+ ions, both of which reduced the GABA-evoked responses. The alpha 6 beta 2 gamma 2 receptor but not the alpha 4 beta 2 gamma 2 receptor exhibited a low level of spontaneous activity in the absence of GABA; this resting current could be directly potentiated by Ro 15-4513, methyl-6,7-dimethoxy-4-ethyl-beta-carboline, bretazenil and flumazenil and was blocked by picrotoxin. Thus, although the alpha 4 beta 2 gamma 2 receptors are insensitive to benzodiazepine binding site full agonists, such as diazepam, they can be modulated by certain ligands acting as partial and inverse agonists at diazepam-sensitive receptors and thereby contribute to the respective pharmacological profiles.

A detailed mapping of the gamma-aminobutyric acid (GABA)A receptor subunits (alpha 1, alpha 2, alpha 3, alpha 5 and beta 2 + 3) in the infralimbic/ventral prelimbic region (IL/vPL) of the rat frontal cortex was carried out using subunit-specific antibodies. The alpha 1 and beta 2 + 3 subunit antibodies immunostained all layers of the IL/vPL region. Layers II and III displayed immunostaining of cell bodies whereas I, V and VI showed predominantly neuropil staining. The size of the alpha 1-positive cell bodies corresponded to that of small interneurons (range, 20-55 microns2; mean +/- SEM, 37 +/- 5.5 microns2) as well as pyramidal cells or large interneurons (range, 87-135 microns2; mean +/- SEM, 103.4 +/- 9.7 microns2). However, beta 2 + 3 antibody immunostained only small cell bodies. Immunoreactivity for alpha 2 was restricted to layers I and II, whereas alpha 3 and alpha 5 subunit expression was seen only in layer VI. The antibody to the alpha 2 subunit immunostained small cell bodies (range, 29-63 microns2; mean +/- SEM, 32 +/- 4.5 microns2) in layer II, resembling interneurons. Conversely, both alpha 3 and alpha 5 antibodies immunostained large cell bodies (range, 94-151 microns2; mean +/- SEM, 115.7 +/- 13.4 microns2), consistent with pyramidal cell labelling in layer VI.

A group of pyrrolopyrimidine derivatives were examined for their interaction with rat recombinant gamma-aminobutyric acid (GABA)A receptors using the whole cell patch clamp and equilibrium binding techniques. In the alpha 1 beta 2 gamma 2 subtype of GABAA receptors expressed in human embryonic kidney cells, a prototype pyrrolopyrimidine, U-89843A (7H-pyrrol[2,3-d]pyrimidine,6,7-methyl-2,4-di- 1-pyrrolidinyl,hydrochloride), dose-dependently enhanced 5 microM GABA-induced Cl- currents with a maximal enhancement of 362 +/- 91%, a half-maximal concentration of 2 +/- 0.4 microM and a slope factor of 1.1 +/- 0.4. The drug also inhibited [35S]t-butylbicyclophosphorothionate binding in rat cerebrocortical membranes with a similar half-maximal inhibitory concentration. The enhancement of Cl- currents by U-89843A was insensitive to Ro 15-1788 (a benzodiazepine antagonist), was also observed in the alpha 3 beta 2 gamma 2 and alpha 6 beta 2 gamma 2 subtypes (no selectivity to different alpha-isoforms unlike many benzodiazepines), but was absent in the receptor subtypes consisting of two subunits (alpha 1 beta 2, alpha 1 gamma 2 and beta 2 gamma 2). It has been known that neurosteroids and barbiturates are uniformly active in both the two subunit receptors, substituted pyrazinones are only active in the alpha 1 beta 2 subtype and loreclezole is active in the subtypes containing beta 2. We propose that U-89843A interacts with an allosteric site on GABAA receptors distinct from the sites for benzodiazepines, barbiturates, neurosteroids, substituted pyrazinones or loreclezole.(ABSTRACT TRUNCATED AT 250 WORDS)

U-90042 is a structurally novel compound that has comparable affinities for binding to three recombinant subtypes of the gamma-aminobutyric acidA receptor: alpha 1 beta 2 gamma 2, alpha 3 beta 2 gamma 2 and alpha 6 beta 2 gamma 2. The relatively high affinity for the alpha 6 beta 2 gamma 2 subtype is similar to the benzodiazepine (BZ) partial inverse agonist Ro 15-4513 and different from BZ sedative/hypnotics such as diazepam and zolpidem. In the present study, U-90042 (3 mg/kg i.p.) suppressed locomotor activity and impaired rotarod performance in mice. These effects were not antagonized by flumazenil. The sedative effect was further confirmed in rats (10 mg/kg i.p.) and monkeys (1 mg/kg p.o.) by an increase of behavioral sleep and a corresponding electroencephalographic frequency spectral shift. Unlike the BZ hypnotics, U-90042 (10 mg/kg i.p.) produced no amnesia in the one-trial passive avoidance response in mice but antagonized diazepam-induced amnesia. In rats trained to discriminate an injection of diazepam from saline, U-90042 produced predominantly vehicle-appropriate responses, even at depressant doses. The in vivo diazepam-antagonist effect of U-90042 is consistent with its low intrinsic activity and diazepam-antagonism at the gamma-aminobutyric acidA alpha 1 beta 2 gamma 2 and alpha 3 beta 2 gamma 2 receptor subtypes. The receptor mechanism for the sedative/hypnotic effect is not clear at this time.

U-93631,[4-dimethyl-3-t-butylcarboxyl-4,5-dihydro (1,5-a) quinoxaline], represents a GABAA receptor ligand of novel chemical structure, and has been shown to induce a rapid, time-dependent decay of GABA-induced whole-cell Cl- currents in recombinant GABAA receptors (Dillon et al., 1993). In this study, we found that the drug competitively inhibited [35S]t-butylbicyclophosphorothionate binding to the picrotoxin site on a cloned GABAA receptor, alpha 1 beta 2 gamma 2, and preempted the action of picrotoxin and [35S]t-butylbicyclophosphorothionate on GABA-induced Cl- currents. We further examined the effect of U-93631 on GABA-induced single channel openings in outside-out patches. U-93631 (5 microM) showed no effect on single channel conductance, the duration of channel open states or the short closed state, but increased the duration of the long closed state and its relative contribution to total closed time. In addition, closings of very long duration (500 msec), albeit rare, occurred more frequently in the presence of U-93631. Thus, the probability of single channel openings decreased from 0.12 +/- 0.02 to 0.04 +/- 0.01 in the presence of U-93631 (5 microM). These properties of U-93631 are analogous to those of picrotoxin and [35S]t-butylbicyclophosphorothionate reported in earlier studies with native neurons. We conclude that U-93631 at least shares overlapping binding domains with picrotoxin and [35S]t-butylbicyclophosphorothionate, and the ability to stabilize the GABAA receptor/Cl- channel complex in an inactivated state(s).(ABSTRACT TRUNCATED AT 250 WORDS)

We describe a versatile array controller developed at RAL and SAAO. The original concept was due to Waltham, van Breda and Newton (1990). A Transputer-based microcomputer forms the heart of the device.

Several previous studies implicated alpha 6 and gamma 2L subunits as potential determinants of gamma-aminobutyric acid A (GABAA) receptor channel sensitivity to alcohol modulation. The effects of ethanol and n-octanol were studied on GABA-induced currents in human embryonic kidney cells transfected to express one of three different GABAA receptor channel subunit combinations: alpha 1 beta 2 gamma 2S, alpha 6 beta 2 gamma 2S or alpha 6 beta 2 gamma 2L. No increase in the current amplitude of any subunit combination was observed after the coapplication of GABA and physiological concentrations (10-100 mM) of ethanol. By contrast, the coapplication of GABA and 100 microM octanol increased the current amplitude by 50% to 100% in all three subunit combinations. Octanol produced a shift of the current dose-response curve toward lower concentrations of GABA. Ethanol was effective in increasing the rate of desensitization produced by higher concentrations of GABA in the alpha 6 beta 2 gamma 2S cells but not the alpha 1 beta 2 gamma 2S combination. This ethanol-induced modification of desensitization was not altered by the presence of the protein kinase inhibitor 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H-7). These experiments indicate that the presence of alpha 6 or gamma 2L subunits, in itself, does not result in the potentiation of GABA-induced currents by ethanol, as described in some reports. However, the presence of either the alpha 6 or alpha 1 subunit may determine whether the desensitization rate of the GABAA current is affected by the alcohol.

A JHKK’ survey camera based on a 1040 × 1040 PtSi “Charge Sweep Device” has been constructed in a joint programme of the University of Tokyo, the National Astronomical Observatory of Japan and the South African Astronomical Observatory. We describe its design, construction and initial testing.

We discovered the ability of U-93631 (4-dimethyl-3-t-butylcarboxyl-4,5- dihydro[1,5-a]imidazoquinoxaline) to accelerate decay of gamma-aminobutyric acid (GABA)-induced currents, and we explored its mechanism in human embryonic kidney cells (HEK-293) stably expressing the alpha 1 beta 2 gamma 2 subtype of GABAA receptors. Inward currents (Cl- efflux) induced by 5 microM GABA at the holding potential of -60 mV (under a symmetrical Cl- gradient) decayed with an exponential time course with a mean time constant (tau) of 222 +/- 25 sec, as examined with the whole-cell configuration of the patch-clamp technique. The monoexponential decay was greatly accelerated in the presence of U-93631 at 5 microM, with the mean tau value being 5.2 +/- 0.5 sec. The tau values were dependent on the concentration of U-93631, with an estimated Kd of approximately 2 microM. Outward currents at the holding potential of +60 mV decayed with a similar tau value in the presence of the drug, suggesting the voltage independence of the drug action. The initial amplitude of the GABA (5 microM)-induced Cl- current was not affected by preincubation with U-93631 (5 microM) or GABA (200 nM) alone but was reduced by preincubation with the combination of the two. In the presence of U-93631 at 5 microM, the peak amplitude decreased as a function of GABA concentration, with the half-maximal inhibitory concentration being approximately 100 nm, which is close to the Kd for the high affinity GABA site (85 nM). It appears that the drug interacts with GABA-bound receptors (at least monoliganded) and accelerates receptor desensitization, rather than acting as an open channel blocker. The binding site for U-93631 on GABAA receptors seems not to overlap with GABA, barbiturate, or benzodiazepine sites, because the drug effect persisted in the presence of excess ligands for those sites. With cloned GABAA receptors composed of only alpha 1 beta 2, beta 2 gamma 2, or alpha 1 gamma 2 subunits, U-93631 also accelerated the decay rate. This lack of subtype selectivity raises the possibility that the compound interacts with a region common among the three subunits, probably a novel modulatory site, which can possibly be exploited as a novel therapeutic target.

Previous studies with cloned gamma-aminobutyric acid type A receptors expressed in human embryonic kidney cells have indicated that the alpha 1 beta 2 gamma 2 and alpha 1 gamma 2 (but not alpha 1 beta 2) subtypes have benzodiazepine sites. We found in this study that even the beta 2 gamma 2 subtype displays gamma-aminobutyric acid-induced Cl- currents that are potentiated by triazolam (a triazolobenzodiazepine). The maximal efficacy of the drug among the subtypes was highest with the alpha 1 beta 2 gamma 2 subtype, followed by the alpha 1 gamma 2 and beta 2 gamma 2 subtypes. These observations led us to compare the ability of several benzodiazepine site agonists of diverse chemical structures to potentiate Cl- currents with these subtypes. With the alpha 1 gamma 2 subtype, diazepam, alpidem, zolpidem, Cl-218872, zopiclone, U-79098 (an imidazoquinoxaline derivative), and U-90167 (a diimidazoquinazoline derivative) at 5 microM potentiated Cl- currents to essentially similar levels (slightly lower for a few ligands), compared with those with the alpha 1 beta 2 gamma 2 subtype. With the beta 2 gamma 2 subtype, the type 1 ligands zolpidem, alpidem, and Cl-218872 showed no or very low levels of potentiation, whereas less selective ligands such as diazepam, zopiclone, U-78098, and U-90167 displayed levels of Cl- current potentiation comparable to those observed with the subtypes containing the alpha 1 and gamma 2 subunits. These data indicate that, in the presence of gamma 2, beta 2 may substitute for alpha 1 in forming the benzodiazepine site of limited sensitivity to the type 1 ligands. It appears that individual ligands for benzodiazepine sites have their own sets of interacting domains, which are distributed in alpha 1 and gamma 2, and the agonistic activity of type 1 ligands may be more dependent on the alpha 1-specific domains than is that of less selective ligands.

1. In this study, we compared two series of newly discovered ligands for their selectivity to benzodiazepine sites in the alpha 1 beta 2 gamma 2 and the alpha 6 beta 2 gamma 2 subtypes of cloned gamma-aminobutyric acidA (GABAA) receptors, the latter being unique in not interacting with classical benzodiazepines. 2. The prototype compounds, U-85575 (12-chloro-5-(5-cyclopropyl-1',2',4'- oxadiazol-3'-yl)-2,3-dihydro-diimidazo [1,5-a;1,2-c]quinazoline), and U-92330 (5-acetyl-3-(5'-cyclopropyl-1',2',4'-oxadiazole-3'-yl)-7-chloro-4,5-d ihy dro [1,5-a]quinoxaline), appear to share an overlapping recognition site with classical benzodiazepines on the GABAA receptor, because their potentiation of GABA-mediated Cl- currents in both subtypes were sensitive to Ro 15-1788, a classical benzodiazepine antagonist. 3. Minor changes in the ring substituents of the drugs reduced their affinity to the alpha 6 beta 2 gamma 2 subtype more pronouncedly than to the alpha 1 beta 2 gamma 2 subtype. The diimidazoquinazoline containing a 2-methyl group which projected below the plane of the rigid ring showed a markedly lower affinity to the alpha 6 beta 2 gamma 2 subtype as compared to its stereoisomer having the methyl group above the plane of the ring. Also, the dihydroimidazoquinoxalines containing the 5-benzoyl group showed a lower affinity to the alpha 6 beta 2 gamma 2 subtype than the 5-acetyl counterpart. In particular, the 5-benzoyl analogue containing a 6-fluoro group showed no interaction with the alpha 6 beta 2 gamma 2 subtype even at the concentration of 10 microM, probably due to stabilization of the benzoyl group in the out-of-plane region by the steric and electrostatic effects of the 6-fluoro group.4. We propose that the benzodiazepine site of the alpha 6 beta 2 gamma 2 subtype shares overlapping regions with that of the alpha 1 beta 2 gamma 2 subtype, but has a sterically restricted out-of-plane region, which may be also incompatible with the 5-phenyl group of classical benzodiazepines.

We discovered substituted pyrazinones as a new class of allosteric modulators of gamma-aminobutyric acid (GABA)A receptors. Prototype pyrazinones, U-92813 [1-(furfuryl)-3,5-dichloro-6-phenylpyrazinone] and U-94863 [1-benzyl-3,5-dichloro-6-(2-chlorophenyl)pyrazinone], potentiated GABA-mediated Cl- currents in cloned GABAA receptors with certain subtype selectivity. The drugs markedly enhanced the GABA response in the alpha 1 beta 2 gamma 2 and alpha 1 beta 2 subtypes but not in the alpha 1 gamma 2 and beta 2 gamma 2 subtypes expressed in human kidney cells. The dose-response profile of U-94863 in the alpha 1 beta 2 subtype was largely indistinguishable from that in the alpha 1 beta 2 gamma 2 subtype, suggesting no critical role for the gamma 2 subunit in potentiation of the GABA response by the pyrazinones. The drugs also potentiated the GABA response in the alpha 3 beta 2 gamma 2 and alpha 6 beta 2 gamma 2 subtypes, indicating their nonselectivity toward the alpha isotypes. With respect to subtype selectivity, the pyrazinones differ not only from ligands for benzodiazepine receptors, which interact only with the subtypes containing alpha beta gamma subunits, but also from barbiturates and neurosteroids, which interact with all the subtypes tested in this study. The unique binding site for U-92813 on GABAA receptors was confirmed by the insensitivity of its action to Ro 15-1788, a classical benzodiazepine antagonist, and by the additive nature of its agonistic activity with that of barbiturates and neurosteroids. With respect to the mechanism of potentiation, the pyrazinones are similar to the other allosteric modulators, in that they potentiate the GABA response more effectively at low GABA concentrations than at high GABA concentrations. We propose that substituted pyrazinones represent a novel class of allosteric modulators of GABAA receptors, with their binding site probably located between the alpha and beta subunits.

The IL-1R antagonist protein (IRAP) is a competitive inhibitor of IL-1, which is predominantly synthesized by monocytes. We show that this molecule is also expressed in human synovial fibroblasts and dermal fibroblasts (CRL 1445). IRAP mRNA was regulated in a time- and dose-dependent manner by IL-1 alpha, TNF-alpha, LPS, and PMA. Maximal induction of IRAP mRNA was observed between 8 and 16 h after stimulation with IL-1 alpha (1 U/ml), TNF-alpha (10 U/ml), LPS (50 ng/ml), and PMA (10 ng/ml). Their relative efficacy was as follows: PMALPSIL-1 alphaTNF-alpha. Potentiation was observed when fibroblasts were treated with IL-1 alpha plus basic fibroblast growth factor and IL-1 alpha plus platelet-derived growth factor-BB homodimer. Although LPS and PMA were the best inducers of IRAP mRNA, quantitation of the IRAP protein revealed that its synthesis and release were differentially regulated. Immunoprecipitation and SDS-PAGE of culture supernatant from LPS-treated cells and cell lysates of fibroblasts treated with LPS or PMA showed a single IRAP band with a molecular mass of approximately 22 kDa. Very little IRAP was detected in culture supernatants of cells treated with PMA. Quantitation of IRAP revealed that LPS induced the synthesis of secreted IRAP that was released, whereas the majority of the protein induced by PMA remained cell-associated. Reverse transcriptase-polymerase chain reaction amplification demonstrated that although LPS and PMA induced both transcripts, LPS preferentially induced secreted IRAP, whereas PMA differentially induced intracellular IRAP mRNA. Fibroblasts synthesize at least two different forms of IRAP depending on the inducing signal, and may regulate the inflammatory response by dampening the proinflammatory effects of IL-1 via a negative feedback mechanism with IRAP. The relative importance of fibroblast sIRAP vs intracellular IRAP in regulating the inflammatory response by the connective tissue remains to be determined.

The alpha 1 beta 2 and alpha 1 beta 2 gamma 2 subtypes, common subtypes of gamma-aminobutyric acid (GABA)A receptors in the brain, are known to share many ligands, but only the latter interacts with benzodiazepines. In this study, we attempted to examine whether the presence of the gamma 2 subunit in the cloned receptors alters the binding properties of GABA and t-butylbicyclophosphorothionate (TBPS) (a highly sensitive probe for conformational changes in the chloride ionophore of GABAA receptors) and their interactions. Using a high-level expression system of SF-9 cells infected with baculovirus, we produced a group of cloned GABAA receptors with variations in the ratio (0 to 3) of the virion carrying the cDNA for the gamma 2 subunit to those carrying the cDNAs for the alpha 1 and beta 2 subunits. The number of benzodiazepine binding sites increased as the level of the gamma 2 virion was raised and reached that of GABA high affinity sites at a gamma 2 to alpha 1 beta 2 ratio of 0.5 or more. It appears that the conversion of the alpha 1 beta 2 to the alpha 1 beta 2 gamma 2 subtype is favorable and complete in the presence of a sufficient level of the gamma 2 subunit, assuming the number of the GABA sites to be equal to the total number of the cloned GABAA receptors. In all preparations, the dissociation constants for flunitrazepam, muscimol, and TBPS were fairly constant, and the maximal number of binding sites for TBPS appeared to be equal to that for muscimol, with no dependence on the gamma 2 virion levels. The effect of GABA on TBPS binding, however, were markedly altered by the gamma 2 subunit. With the alpha 1 beta 2 subtype GABA at concentrations occupying its high affinity sites markedly stimulated but at higher concentrations (micromolar ranges) inhibited TBPS binding, whereas with the alpha 1 beta 2 gamma 2 subtype GABA inhibited TBPS binding without the early stimulatory phase. We also confirmed the selective interaction of Zn2+ (50 microM) with the alpha 1 beta 2 subtype, as probed with TBPS binding, and observed a progressive disappearance of Zn2+ sensitivity as the gamma 2 virion level increased.(ABSTRACT TRUNCATED AT 400 WORDS)

U-78875 [imidazo[1,5-a]quinoxalin-4(5H)-one, 3-(5-cyclopropyl-1,2,4-oxadiazol-3-yl)-5-(1-methylethyl)] belongs to a series of imidazoquinoxaline derivatives, recently discovered ligands with high affinity for benzodiazepine receptors. In this study, we have examined the drug and its analogs for their modes of interaction with the receptors, with a particular emphasis on finding molecular determinants for their functional properties. Changes in the substituents on N5 and C6 of the heterocyclic ring produced no major effects on binding characteristics but yielded drugs of widely varying efficacy (antagonist to full agonist), measured as gamma-aminobutyric acid (GABA)-mediated 36Cl- uptake and t-butylbicyclophosphoro[35S]thionate binding in rat cerebrocortical membranes. The relative binding affinity and efficacy of the analogs measured in brain membranes were similar to those in cloned GABAA receptors of the alpha 1 beta 2 gamma 2 (type I) and alpha 3 beta 2 gamma 2 (type II) subtypes. The imidazoquinoxalines showed no marked subtype selectivity. Their Ki value against [3H]flunitrazepam binding for type I was only 2-3 times lower than that for type II, and their rank order for agonistic activity was the same in the two subtypes, measured as GABA-mediated Cl- currents in human kidney cells (A293) expressing the subtypes of GABAA receptors. According to computational modeling of the drugs using both molecular and quantum mechanics, the agonistic activity of the imidazoquinoxaline derivatives depends on the presence of a bulky alkyl substituent at N5 and the deformation of the substituted portion of the otherwise planar ring system induced by a bulky moiety at N5 or C6. With a fixed N5 substituent (isopropyl), the relative efficacy in the brain membranes, as well as in the cloned receptors, appeared to be dependent on the degree of the ring deformation. This out-of-plane portion of the imidazoquinoxalines can be assigned to the general region occupied by the 5-phenyl group of diazepam and other agonistic functional groups of several nonbenzodiazepine ligands. It seems that this region, apparently common to various agonistic ligands, interacts with an agonistic pocket in type I and type II subtypes of the benzodiazepine receptors in the brain. Our results also provide direct support for the view that the agonists and nonagonists share largely overlapping binding regions in the benzodiazepine receptor, which has been proposed earlier from in vivo efficacy measurements of other series of ligands.

The cytokine interleukin-1 (IL-1) has a number of biologic activities, including pronounced effects on the nervous and neuroendocrine systems. In this study, in situ histochemical techniques were used to investigate the distribution of cells expressing type I IL-1 receptor mRNA in the CNS, pituitary, and adrenal gland of the mouse. Hybridization of 35S-labeled antisense cRNA probes derived from a murine T-cell IL-1 receptor cDNA revealed a distinct regional distribution of the type I IL-1 receptor, both in brain and in the pituitary gland. In the brain, an intense signal was observed over the granule cell layer of the dentate gyrus, over the entire midline raphe system, over the choroid plexus, and over endothelial cells of postcapillary venules throughout the neuraxis. A weak to moderate signal was observed over the pyramidal cell layer of the hilus and CA3 region of the hippocampus, over the anterodorsal thalamic nucleus, over Purkinje cells of the cerebellar cortex, and in scattered clusters over the external-most layer of the median eminence. In the pituitary gland, a dense and homogeneously distributed signal was observed over the entire anterior lobe. No autoradiographic signal above background was observed over the posterior and intermediate lobes of the pituitary, or over the adrenal gland. This study therefore provides evidence for discrete receptor substrates subserving the central effects of IL-1, thus supporting the notion that IL-1 acts as a neurotransmitter/neuromodulator in brain. It also supports studies suggesting that IL-1-mediated activation of the hypothalamic-pituitary- adrenal axis occurs primarily at the level of the brain and/or pituitary gland.

We describe a versatile array controller developed at RAL and SAAO. The original concept was due to Waltham, van Breda and Newton (1990). A Transputer-based microcomputer forms the heart of the device.

Our previous studies have demonstrated that platelet-derived growth factor (PDGF) modulated cellular responses to interleukin-1 (IL-1). In this communication, we show that PDGF regulates expression of IL-1 receptor (IL-1 R) gene. Treatment of quiescent cultures of Balb/c 3T3 fibroblasts with PDGF produced 20-30-fold stimulation of IL-1 R mRNA with a concomitant increase in cell surface 125I-binding. IL-1 R mRNA accumulation occurred after an initial lag period and with a time course preceding the increase in 125I-IL-1 binding to cells. Induction of IL-1 R mRNA was blocked by inhibitors of protein synthesis, suggesting that a product of a gene expressed immediately after PDGF addition is required for IL-1 R gene expression. These latter data provide evidence for an ordered sequence of expression of PDGF-inducible "immediate early" gene(s) and IL-1 R gene. These results suggest that in connective tissues, PDGF may be an important determinant in initiating and maintaining cellular responses to IL-1. Such responses may have important consequences in the actions of IL-1 under normal and pathological conditions such as arthritis and atherosclerosis.

This paper describes the results of a systematic study of the interaction of cable systems with ionizing radiation fields, with a view toward achieving a fundamental understanding of the effects governing radiation induced cable signals. The study led to the construction of a physical model which was used to obtain a quantitative description of the dominant processes involved in the interaction. The model is sufficiently comprehensive to permit the calculation of the current induced in the conductors of a coaxial or triaxial cable system (or, indeed, almost any other system of conductors separated by an insulating medium) for any combination of incident photon and electron spectra. A number of experiments was performed to support the calculations. The validity of the model will be demonstrated by showing that the experimental data verify the theoretical calculations.

In this study the influence of old age on adrcnocortical function and cortisol metabolism was investigated, along with renal, hepatic and thyroid function in 15 young men (25–40 years old) and 50 old men (60–96 years old). By the criteria of 8-a.m. plasma levels of free and conjugated 17-hydroxycorticosteroids (17-OH-CS) and the plasma corticoid response to ACTH stimulation, no significant change in adrenocortical function could be demonstrated with advancing age. However, there was a progressive and significant decrease in the urinary excretion of 17-OH-CS with aging. Following intravenous administration of a standard dose, cortisol disappeared from the circulation at a significantly slower rate in the old men. The maximal levels of plasma conjugated 17-OH-CS observed after cortisol infusion were statistically the same for all ages, but the rate of decay from peak values was slower in the older subjects. These alterations in cortisol metabolism were associated with a significant increase in the level of ...

Our previous studies have demonstrated that platelet-derived growth factor (PDGF) modulated cellular responses to interleukin-1 (IL-1). In this communication, we show that PDGF regulates expression of IL-1 receptor (IL-1 R) gene. Treatment of quiescent cultures of Balb/c 3T3 fibroblasts with PDGF produced 20-30-fold stimulation of IL-1 R mRNA with a concomitant increase in cell surface 125I-binding. IL-1 R mRNA accumulation occurred after an initial lag period and with a time course preceding the increase in 125I-IL-1 binding to cells. Induction of IL-1 R mRNA was blocked by inhibitors of protein synthesis, suggesting that a product of a gene expressed immediately after PDGF addition is required for IL-1 R gene expression. These latter data provide evidence for an ordered sequence of expression of PDGF-inducible "immediate early" gene(s) and IL-1 R gene. These results suggest that in connective tissues, PDGF may be an important determinant in initiating and maintaining cellular responses to IL-1. Such responses may have important consequences in the actions of IL-1 under normal and pathological conditions such as arthritis and atherosclerosis.