Association of the ANTXR2 gene polymorphism and ankylosing spondylitis in Chinese Han

OBJECTIVE

Ankylosing spondylitis (AS) is an inflammatory disease of unknown origin. Both genetic and environmental factors are involved. A recent genome-wide association study (GWAS) found anthrax toxin receptor 2 (ANTXR2) to be associated with AS in Caucasians. We aimed to investigate whether the ANTXR2 polymorphism is also associated with AS in a Chinese Shandong Han population.

METHODS

From 2008 to 2009, we recruited 309 patients with AS and 384 age- and sex-matched controls of Han nationality. We selected six single nucleotide polymorphisms (SNPs) of ANTXR2 (rs4333130, rs6534708, rs6818557, rs12646132, rs12509658, and rs13140055) and genotyped them by polymerase chain reaction restriction fragment-length polymorphism (PCR-RFLP) and Taqman methods. We analysed linkage disequilibrium and constructed haplotypes.

RESULTS

Cases and controls did not differ in the frequency of ANTXR2 alleles, genotypes, or haplotypes. Thus, the six SNPs of ANTXR2 are not associated with AS in our Chinese Shandong Han population.

CONCLUSIONS

ANTXR2 might not be a susceptibility gene of AS in Chinese Han.

Performance and kinetic evaluation of anaerobic moving bed biofilm reactor for treating milk permeate from dairy industry

High strength milk permeate derived from ultra-filtration based cheese making process was treated in an anaerobic moving bed biofilm reactor (AMBBR) under mesophilic (35 degrees C) condition. Total chemical oxygen demand (TCOD) removal efficiencies of 86.3-73.2% were achieved at organic loading rates (OLR) of 2.0-20.0 g TCOD L(-1) d(-1). A mass balance model gave values of methane yield coefficient (Y(G/S)) and cell maintenance coefficient (k(m)) of 0.341 L CH(4) g(-1) TCOD(removed) and 0.1808 g TCOD(removed) g(-1) VSS d(-1), respectively. The maximum substrate utilization rate U(max) was determined as 89.3 g TCOD L(-1) d(-1) by a modified Stover-Kincannon model. Volumetric methane production rates (VMPR) were shown to correlate with the biodegradable TCOD concentration through a Michaelis-Menten type equation. Moreover, based on VMPR and OLR removed from the reactor, the sludge production yield was determined as 0.0794 g VSS g(-1) TCOD(removed).

Alterations of immune functions induced by 12C6+ ion irradiation in mice

PURPOSE

To estimate the biological risks to the immune system of the type of space radiation, 12C6+, encountered by cosmonauts during long-term travel in space.

MATERIALS AND METHODS

The Kun-Ming strain mice were whole-body irradiated by 12C6+ ion with 0, 0.01, 0.05, 0.075, 0.2, 0.3, 0.5, 0.75, 1 or 2 Gy, at a dose rate of 1 Gy/min. At 35 days after irradiation, the thymus and spleen weights were measured, the natural killer (NK) cells activity of spleen was determined by 3-(4, 5-dimethylthiazol-2-yl)- 2, 5-diphenyl tetrazolium bromide (MTT), and the interferon-gamma (IFN-gamma) levels in serum and thymus were detected with enzyme-linked immunosorbent assays (ELISA).

RESULTS

The results showed that the thymus weight, IFN-gamma levels in serum and the activity of splenic NK-cells had significantly increased at a dose of 0.05 Gy. With further dose increase, the weight of spleen continued to increase but the weight of thymus, IFN-gamma level and NK-cells activity declined.

CONCLUSIONS

These results suggest that the dose of 0.05 Gy irradiation has a stimulatory effect on mouse immunity; this effect declined with increasing dose.

Microarchitecture and Spatial Relationship Between Bacteria and Ileal, Cecal, and Colonic Epithelium in Chicks Fed a Direct-Fed Microbial, PrimaLac, and Salinomycin

Direct-fed microbials (DFM) could serve as a potential alternative to the feeding of antibiotics in poultry production. In this study, the effects of providing a DFM were compared with the feeding of salinomycin on intestinal histomorphometrics, and microarchitecture was examined. Broiler chicks (n=18 per treatment; trials 1 and 2) were fed a standard starter diet (control), control+PrimaLac (DFM; 0.3% wt/wt), and control+salinomycin (SAL; 50 ppm) from hatch to 21d. The birds were euthanized on d 21, and the ileal, jejunal, cecal, and colon tissues were dissected. Samples were examined by light microscopy (jejunum and ileum; trial 1) and scanning electron microscopy (ileum, cecum, and colon; trial 2). Feeding of the DFM increased intestinal muscle thickness (P<0.05) up to 33% compared with the control treatment. The DFM group also had increased villus height and perimeter (P=0.009 and 0.003, respectively) in jejunum. Segmented filamentous-like bacteria were less numerous in DFM-treated chicks than in the control chicks. Very few segmented filamentous-like bacteria were found near other microbes in the ileum. The DFM chicks had a larger number of bacteria positioned over or near goblet cells and in intervilli spaces. Bacteria in the colon were observed to be attached primarily around and within the crypts. Mucous thickness was less, and the density of bacteria embedded in the mucous blanket appeared to be lower in DFM-treated animals than in the control in all intestinal segments. The birds fed SAL had fewer bacteria and enterocytes in the ileum than in the control-and DFM-treated birds, and they had thicker and fewer microvilli. Because gastrointestinal track colonization by the DFM organisms can prevent the attachment of pathogens to the epithelium, spatial relationships, in this study, demonstrate the functionality of DFM and probiotics in preventing disease. It also supports previous observations that the feeding of salinomycin may alter intestinal function.

High-level dosimetry at the demagnetization experiments of permanent magnets

The measurements of high-energy and high dose mixed radiation from high-energy electron accelerator are carried out using a radiation damage monitor. It consists of two Radiation-Sensing Field-Effect Transistors (RADFETs) for total absorbed dose from mainly gamma ray and other charged particles and a Si PIN diode for neutron fluence. This is a part of the demagnetization study of rare earth permanent magnet irradiated by 2.5-GeV electron beam. The sensitivities of damage detectors are measured using 65-MeV quasi-monoenergic neutron, 14-MeV D-T neutron, (252)Cf neutron for Si PIN diode and (60)Co and (137)Cs gamma ray for RADFETs. Measured sensitivities are in acceptable range in the comparison of producer's proposed values. The dose and fluence measurements are carried out for the same target condition, Cu and Ta, as that for the demagnetization study. The 5 x 5 cm(2) cross-sectional and 5.5-cm-thick Pb target is also used for the general comparison with photoneutron yields. All measured dose and fluence are compared with the calculated results using the FLUKA code and agree well each other. The application of this kind of radiation damage monitor to high-level dosimetry at high-energy electron accelerator has been discussed.

[Trihalomethane formation potential (THMFP) of soils in Guangdong Province]

Trihalomethane formation potentials were analyzed with the lixivia of typical soil samples in Guangdong Province. The results showed that the bulk THMFP contents of soil lixivia (b-THMFP) range from 0.7 to 36.8 micrograms/g with a median value of 10.6 micrograms/g, and the THMFP contents of 0.45 micron filtered soil lixivia, representing the THMFP contents of dissolved organic matter (d-THMFP), from 0.5 to 21.2 micrograms/g with a median value of 3.9 micrograms/g. Sample 19 (Calcareous soil) had the highest b-THMFP and d-THMFP while sample 20 (Purple soil) had the lowest b-THMFP and sample 5 (Latored soil) had the lowest d-THMFP. In general, suspended organic matter had great contribution to the THMFP. The physico-chemical properties, such as organic matter contents and contents of various oxides, as well as soil genetic horizon and vegetation are main factors dominating the THMFP levels in the soil.

[Complexing mechanism on extraction of DHA ester using silver ion]

Ultraviolet spectra of docosahexaenoic acid (DHA) ester and its complex with silver ion were determined, and shifts of ultraviolet absorption peak before and after the complexing reaction were observed. Meanwhile, complexing bonds of DHA ester-silver ion were explained by molecular orbital theory. Thus, complex structure and complexing mechanism were discovered. The results showed that ultraviolet characteristic absorption peak of DHA ester-silver ion complex moved to lower wavelength. It pointed out that distance between energy levels for outer electron transition of complex is increased, and the energy for outer electron transition of complex is bigger than that of DHA ester.

[Decomposition of aqueous sodium pentachlorophenolate (PCP-Na) by using TiO2 coating photocatalyst]

Titanium dioxide (TiO2) photocatalysts were coated on hollow glass beads by sodium silicate (Na2SiO3.9H2O) solution. The coated catalysts were characterized by BET, XRD. Their photoactivity were examined using photocatalytic degradation of sodium pentachlorophenolate(PCP-Na) and glucose solution. The impact of catalysts dosage, PCP-Na initial concentration, initial pH and oxygen concentration on reaction kinetics were also studied in detail. The experiments illustrated that the performance of C3-type catalysts was satisfactory. Conditions of the experiments were following: The initial concentration of PCP-Na and CODCr were 10 mg.L-1 and 400 mg.L-1, respectively, and illumination time was 2 hours and catalysts dosage was 2 g.L-1, the removal rates of CODCr and PCP-Na were above 65% and 92% respectively. Optimum dosage of C3-type catalysts was 2-2.5 g.L-1, DO was no less than 3 mg.L-1.

Effects of xin mai tong capsule on vasoregulatory peptides in the patients of coronary heart disease

In order to inquire into the therapeutic effects of Xin Mai Tong Capsule ([symbol: see text]) on coronary heart disease with myocardial ischemia, 40 patients were randomly divided into two groups (Xin Mai Tong group and the control group). The plasma endothelin (ET) levels in the two groups of patients were markedly higher than that of the healthy people (P < 0.001), and the calcitonin gene related peptide (CGRP) was similar to that of the healthy people (P > 0.05). After treatment, ET and symptomatic scores in the two groups decreased markedly (P < 0.01), and their S-T segments were elevated obviously (P < 0.01). But the decrease of ET and symptomatic scores and elevation of S-T segment in Xin Mai Tong group were superior to those of the control group (P < 0.05-0.01). The CGRP level in the control group did not vary obviously post-treatment, but it increased markedly (P < 0.01) with the addition of Xin Mai Tong Capsule in Xin Mai Tong group.

Synaptojanin 2, a novel Rac1 effector that regulates clathrin-mediated endocytosis

The small GTPase Rac has been implicated in a wide range of cellular processes, including the organization of the actin cytoskeleton, transcriptional control and endocytic vesicle trafficking [1-3]. The signaling components that mediate these functions downstream of Rac largely remain to be identified. In this study, we have identified synaptojanin 2, a polyphosphoinositide phosphatase as a novel Rac1 effector. Synaptojanin 2 directly and specifically interacts with Rac1 in a GTP-dependent manner. Expression of constitutively active Rac1 caused the translocation of synaptojanin 2 from the cytoplasm to the plasma membrane. Both activated Rac1 and a membrane-targeted version of synaptojanin 2 inhibited endocytosis of the epidermal growth factor (EGF) and transferrin receptors, a process that is known to be dependent on polyphosphoinositide lipids. Endocytosis of growth factor receptors is thought to play an important role in the regulation of cell proliferation. Thus, these results suggest that synaptojanin 2 may mediate the inhibitory effect of Rac1 on endocytosis and could contribute to Rac1-mediated control of cell growth.

Cloning and sequencing of sialyltransferase gene from human fetal liver

Based on sequences of the highly conserved segments in the previously cloned sialyltransferases, 150 bp fragments were amplified and sequenced using human fetal liver mRNA as template. One of them (s38) showed 57%-97% identities with the active domains of previously cloned sialyltransferases. Based on the sequence of s38, an oligonucleotide was synthesized and labeled to screen human fetal liver cDNA library. A cDNA encoding alpha 2, 3-sialyltransferase has been isolated. The cDNA sequence included an open reading frame coding for 340 amino acid residues, and the deduced amino acid sequence showed 100% identity with that of human submaxillary gland Gal beta 1, 3GalNAc alpha 2, 3-sialyltransferase, 83.2% identity with that of pig submaxillary gland alpha 2, 3-sialyltransferase. These results suggested that the protein encoded by the cDNA from human fetal liver cDNA library was a Gal beta 1, 3GalNAc alpha 2, 3-sialyltransferase.

[Effect of xinmaitong capsule on total ischemia burden in coronary heart disease patients with myocardial ischemia and analysis of its therapeutical mechanism]

OBJECTIVE

To assess the effect of Xinmaitong (XMT) capsule in treating ischemical cardiac disease.

METHODS

Sixty coronary heart disease (CHD) patients with myocardial ischemia were divided randomly into two groups. XMT group (30 cases) was treated with XMT plus western medicine, and control group (30 cases) with western medicine alone. The changes of the scores for clinical symptoms, the total ischemia burden (TIB), the plasma endothelin (ET), the nitric oxide (NO), the superoxide dismutase (SOD), and the malonyldialdeyde (MDA) levels were observed before and after treatment.

RESULTS

After treatment with XMT the scores of clinical symptoms, TIB, ET and MDA levels were significantly decreased (P < 0.01), the levels of NO and SOD were significantly increased (P < 0.01) in the XMT group, comparing with the control group these changes were statistically different (P < 0.01).

CONCLUSIONS

XMT capsule can act against myocardial ischemia effectively, one of the mechanisms of which is protecting the function of vascular endothelium and resisting lipid peroxidation injury. The effects of adding XMT capsule on conventional treatment of western medicine were better than those of using western medicine alone.

Physical and biological properties of cationic triesters of phosphatidylcholine

The properties of a new class of phospholipids, alkyl phosphocholine triesters, are described. These compounds were prepared from phosphatidylcholines through substitution of the phosphate oxygen by reaction with alkyl trifluoromethylsulfonates. Their unusual behavior is ascribed to their net positive charge and absence of intermolecular hydrogen bonding. The O-ethyl, unsaturated derivatives hydrated to generate large, unilamellar liposomes. The phase transition temperature of the saturated derivatives is very similar to that of the precursor phosphatidylcholine and quite insensitive to ionic strength. The dissociation of single molecules from bilayers is unusually facile, as revealed by the surface activity of aqueous liposome dispersions. Vesicles of cationic phospholipids fused with vesicles of anionic lipids. Liquid crystalline cationic phospholipids such as 1, 2-dioleoyl-sn-glycero-3-ethylphosphocholine triflate formed normal lipid bilayers in aqueous phases that interacted with short, linear DNA and supercoiled plasmid DNA to form a sandwich-structured complex in which bilayers were separated by strands of DNA. DNA in a 1:1 (mol) complex with cationic lipid was shielded from the aqueous phase, but was released by neutralizing the cationic charge with anionic lipid. DNA-lipid complexes transfected DNA into cells very effectively. Transfection efficiency depended upon the form of the lipid dispersion used to generate DNA-lipid complexes; in the case of the O-ethyl derivative described here, large vesicle preparations in the liquid crystalline phase were most effective.

Molecular cloning and expression of Galbeta1,3GalNAc alpha2, 3-sialyltransferase from human fetal liver

Based on the sequences of the highly conserved segments in the previously cloned sialyltransferases, a cDNA encoding Galbeta1, 3GalNAc alpha2,3-sialyltransferase (SIATFL) has been isolated from human fetal liver. Expression analysis of the gene has been performed with various carcinoma cell lines, fetal tissues, fetal and adult liver and both hepatoma and the surrounding tissue from the same liver. The SIATFL gene was expressed poorly in fetal liver and in adult liver, slightly in hepatoma and highly in the surrounding tissue of hepatoma. The cDNA encoding the putative active domain was expressed in COS-1, Escherichia coli, and Pichia pastoris. The recombinant protein expressed in COS-1 could catalyse the transfer of NeuAc from CMP-NeuAc to asialo-fetuin. No enzyme activity was detected with a 32-kDa protein in E. coli and both 32-kDa and 41-kDa proteins in P. pastoris. These results suggested that correct glycosylation of the enzyme might play a key role in its folding that may be directly related to the enzymatic activity.

A role for guanyl nucleotide-binding regulatory protein beta- and gamma-subunits in the expression of the adrenocorticotropin receptor

Mutant Y1 mouse adrenocortical tumor cells, isolated on the basis of their resistance to the growth-inhibitory effects of forskolin, arise from single mutational events. These mutants present complex phenotypes in which the activity of Gbeta/gamma is impaired, ACTH receptor gene expression is markedly diminished, and ACTH-responsive adenylyl cyclase activity is lost. In this study, we have tested the hypothesis that the impairment in Gbeta/gamma activity is responsible for the loss of ACTH receptor gene expression and ACTH-responsive adenylyl cyclase activity. Transfection of one of the mutant clones with expression vectors encoding either Gbeta1 or Gbeta2 together with Ggamma2 increased ACTH receptor expression and restored ACTH-responsive adenylyl cyclase activity. Interestingly, either Gbeta2 or Ggamma2 alone was effective. These results thus support the hypothesis that the impairment in Gbeta/gamma activity is responsible for the loss of ACTH receptor expression. A luciferase reporter plasmid driven by the proximal promoter region of the mouse ACTH receptor gene was expressed poorly in the mutants compared with parental Y1 cells, suggesting that the Gbeta/gamma defect compromised transcriptional activity at the proximal promoter region of the ACTH receptor gene.

[Clinical study on protective effect of xinmaitong capsule on damage of vascular endothelial cells]

OBJECTIVE

To assess the effect of Xinmaitong (XMT) capsule in treating coronary heart disease (CHD).

METHODS

Thirty-eight patients of coronary heart disease with myocardial ischemia were divided randomly into XMT group (20 cases) and control group (18 cases). Conventional western medical therapy was given to both groups and the XMT group received additional XMT treatment. The changes of endothelin (ET) and calcitonin gene-related peptide (CGRP) levels, ST segment of ECG and clinical symptoms after treatment in all the patients were observed. Data of 14 healthy persons were taken as normal control.

RESULTS

The ET level of all patients was significantly higher than that of the normal control (P < 0.001), and level of CGRP in patients was not different from normal control significantly (P > 0.05). After treatment, results showed that: (1) The ET levels and the scores of clinical symptoms of both groups decreased significantly (P < 0.01), and ST segment elevated markedly (P < 0.01) as compared with before treatment, and the changes revealed more evident in XMT group in comparison with those of the control group (P < 0.05-P < 0.01). (2) The level of CGRP was significantly increased in XMT group (P < 0.01) while unchanged in the control group (P > 0.05).

CONCLUSIONS

There is severe damage of vascular endothelial cells in CHD patients. XMT could not only reduce significantly the plasma ET content, but also enhance markedly the production and release of CGRP, so it has a good anti-ischemic effect, which may be closely related with its action on improving the function of vascular endothelial cells and regulating metabolism of ET and CGRP.

[Distribution of 70kDa heat shock protein in rabbit brains after heat stress and heat stroke]

OBJECTIVE

Evaluation of the relationship between the induction of 70kDa heat shock protein in rabbit brains and heat stress.

METHODS

HSP70 was detected using monoclonal antibody by ABC method in rabbit hypothalamus, hippocampus and cerberal cortex.

RESULTS

Intense HSP70 staining was displayed in rabbit brains of the heat stroke group (rectal temperature 43 degrees C to death). Positive cells were distributed mainly in the CA1, CA2 regions of the hippocampus; granular cell layer I and pyramidal layer (II) of the cerebral cortex; and the periventricular area of hypothalamus. HSP70-psoitive substances were localized in the cytoplasm and neuronal processes, a few neurons exhibited dark staining nucle. Hosever, the rabbit brains of the general heat stress group (rectal temperature 42.0 degrees C, 30 minutes) had much weaker staining.

CONCLUSION

Hyperthermia causes neuronal expression of HSP70, particularly under strong heat stress, and may be sustained till death.

Mutations to forskolin resistance result in loss of adrenocorticotropin receptors and consequent reductions in levels of G protein alpha-subunits

A family of mutants isolated from the Y1 mouse adrenal cell line on the basis of their resistance to the growth inhibitory effects of forskolin have an underlying mutation that affects the activity of adenylyl cyclase. As part of the mutant phenotype, adenylyl cyclase is partially resistant to activation by forskolin, completely insensitive to ACTH, and fully responsive to NaF; the levels of Gs alpha and G1 alpha in plasma membrane fractions are decreased; and the activity of G beta/gamma is impaired. In the present study, we examine the basis for the complex phenotype associated with forskolin resistance to better understand the factors that contribute to the regulation of adenylyl cyclase activity. We demonstrate that the resistance of these mutants to ACTH results from the failure to express ACTH receptor transcripts. Transfection of these mutants with a gene encoding the mouse beta 2-adrenergic receptor led to the recovery of transformants with normal receptor-G protein coupling and with increased levels of Gs alpha and G1 alpha that approached those in parental Y1 cells. These beta 2-adrenergic receptor transformants, nonetheless, remained resistant to forskolin and ACTH. Two spontaneous Y1 mutants, Y6 and OS3, previously characterized as ACTH-resistant clones that failed to accumulate ACTH receptor transcripts, were shown to be forskolin resistant and to contain less Gs alpha in membrane fractions, indicating that forskolin resistance, failure to express the ACTH receptor, and the consequent reduction in Gs alpha are closely linked. Expression of the human ACTH receptor in Y6 and OS3 cells restored ACTH-responsive adenylyl cyclase activity and increased the level of Gs alpha, but did not otherwise reverse the forskolin-resistant phenotype. Together, these results demonstrate that mutations to forskolin resistance have downstream consequences that result in the loss of ACTH receptor expression and the consequent reduction in levels of membrane-associated G alpha subunits. The results further suggest that G protein-coupled receptors may have a stabilizing influence on G alpha subunits associated with the cell membrane. According to current models, forskolin activates adenylyl cyclase by forming a ternary complex with adenylyl cyclase and Gs alpha. Our results suggest that this model may be incomplete and that an additional component, acting directly or indirectly, is required for optimal activation of adenylyl cyclase by forskolin.

Stabilization of helical peptides by mixed spaced salt bridges

Whether or not surface salt bridges have a strong stabilizing effect on the native structure in proteins remains uncertain. Previous studies of model peptides have shown that salt bridges spaced at i,i +4 along the chain are more stabilizing than those spaced at i,i +3, with a preference for the order acid-base rather than base-acid from N to C terminus. An analysis of the effect of spacing the ion pairs in short helical peptides is presented, in which acidic and basic side chains spaced two or three residues apart alternate along the chain. The mixed spacing proves to be stabilizing relative to pure spacings. A control peptide in which salt bridges were spaced uniformly three residues apart proved to form a beta-sheet structure rather than alpha-helix. This is due to formation of a silk-like apolar face consisting of alanine side chains; the mesoscopic structure formed by these sheets can be imaged by scanning microscopy.

cDNA for the beta 1 subunit of guanyl nucleotide-binding regulatory proteins from mouse adrenal glands

cDNA encoding the beta 1 subunit of guanyl nucleotide binding regulatory proteins was isolated from a mouse adrenal cDNA library. The coding region was 90% identical to human and bovine beta 1 at the cDNA level and 100% identical at the protein level. In the 5' untranslated region, two sequence variants were isolated that differed by the presence or absence of a 49 base pair insert presumed to arise from alternative splicing.

Delivery of membrane-impermeant fluorescent probes into living neural cell populations by lipotransfer

Use of fluorescent probes to monitor f-actin in living cells typically relies on difficult microinjection procedures. The current work has developed cationic lipotransfer of membrane-impermeant probes as an alternative to microinjection. BODIPY FL-phallacidin, a fluorescent f-actin probe, was packaged into 40-50 nm cationic liposomes. Packaging, verified by gel filtration, enabled delivery of the probe into living nerve cells and provided an image of f-actin that was identical to that seen in fixed, permeabilized cells. Phallacidin alone did not enter living cells, nor was its uptake stimulated by the presence of empty liposomes. All predicted f-actin structures were fluorescent in living cells, indicating a high efficacy of delivery. Cationic lipotransfer of fluorescent probes was rapid, not disruptive to cells, and delivered a probe en masse to a large sample population. Lipotransfer appears to be a promising alternative to microinjection for introducing membrane-impermeant probes and reagents into living cells.

Adrenocorticotropin-resistant mutants of the Y1 adrenal cell line fail to express the adrenocorticotropin receptor

This report examines the basis for adrenocorticotropin (ACTH) resistance in two mutant clones (Y6 and OS3) derived from the ACTH-responsive Y1 mouse adrenocortical tumor cell line. These two mutants were originally characterized by their failure to respond to ACTH with increased adenylyl cyclase activity and as a consequence were resistant to the steroidogenic effects of the hormone. We now demonstrate that ACTH resistance in the Y6 and OS3 mutants results from the failure to express the gene encoding the ACTH receptor. Whereas parental Y1 cells express ACTH receptor transcripts at low levels and are stimulated by ACTH or 8-bromo-cAMP to increase the accumulation of ACTH receptor transcripts approximately twofold, the Y6 and OS3 mutants do not express receptor transcripts either in the presence or absence of 8-bromo-cAMP. The gene encoding the ACTH receptor appears to be present in the Y6 and OS3 mutants, as determined by Southern blot hybridization analysis. Moreover, in the Y6 mutant the ACTH receptor gene appears to be silenced by a modification that is reversed following the growth of the cells as tumors in mice. Clonal isolates of Y6 cells grown as tumors recover the ability to express ACTH receptor transcripts at low but detectable levels and acquire the ability to respond to ACTH with increased adenylyl cyclase activity. Finally, Y6 and OS3 cells transformed with a gene encoding the mouse beta 2-adrenergic receptor respond to the beta-adrenergic agonist, isoproterenol, in a manner that is indistinguishable from the similarly transformed parent Y1 cell line. These latter results demonstrate the functional integrity of the adenylyl cyclase system in the ACTH-resistant mutants and indicate that the failure to express ACTH receptor transcripts limits the responsiveness of these clones.

ACTH-receptor deficient mutants of the Y1 mouse adrenocortical tumor cell line

Two mutant clones (Y6 and OS3) derived from the ACTH-responsive Y1 mouse adrenocortical tumor cell line fail to respond to ACTH with increased adenylyl cyclase activity and, as a consequence, are resistant to the steroidogenic effects of the hormone. As determined from Northern blot and RNase protection assays, ACTH resistance in these mutants results from the failure to accumulate ACTH receptor transcripts. The ACTH receptor gene appears to be present in these mutants as determined by Southern blot hybridization analysis and can be activated following the growth of the mutant cells as tumors in mice, suggesting that the ACTH receptor gene is modified in a reversible manner. When mutant cells are transformed with a gene encoding the mouse beta 2-adrenergic receptor they respond to beta-adrenergic agonists with increased adenylyl cyclase activity in a manner that is indistinguishable from a similarly transformed parent Y1 cell line. These results suggest that the adenylyl cyclase system in the mutants is otherwise intact and that the failure to express ACTH receptor transcripts limits the responsiveness of these clones to the hormone.

Neurotransmitter release evoked by nerve impulses without Ca2+ entry through Ca2+ channels in frog motor nerve endings

1. The requirement for extracellular Ca2+ in the process of evoked acetylcholine (ACh) release by nerve impulses was tested at endplates in frog skeletal muscle. Ca(2+)-containing lipid vesicles (Ca2+ liposomes) were used to elevate cytoplasmic Ca2+ concentrations under conditions in which Ca2+ entry from the extracellular fluid was prevented. 2. In an extracellular solution containing no added Ca2+ and 1 mM Mg2+ ('Ca(2+)-free' solution), Ca2+ liposomes promoted the synchronous release of ACh quanta, reflected electrophysiologically as endplate potentials (EPPs), in response to temporally isolated nerve impulses. 3. Motor nerve stimulation generated EPPs during superfusion with Ca2+ liposomes in Ca(2+)-free solutions containing the Ca2+ channel blocker Co2+ (1 mM), and the Ca2+ chelator EGTA (2 mM). As a physiological control for Ca2+ leakage from the liposomes to the extracellular fluid, the effect of Ca2+ liposomes on asynchronous evoked ACh release mediated by Ba2+ was examined. In contrast to the effects of 0.2-0.3 mM extracellular Ca2+, which generated EPPs but antagonized Ba(2+)-mediated asynchronous ACh release, Ca2+ liposomes generated EPPs but did not reduce asynchronous release mediated by Ba2+. The effects of Ca2+ liposomes were thus not due to leakage of Ca2+ from the liposome to the extracellular fluid. 4. Morphological studies using fluorescently labelled liposomes in conjunction with a confocal microscope demonstrate that lipid is transferred from the liposomes to nerve endings and liposomal contents are delivered to the nerve terminal cytoplasm. 5. The results suggest that when intracellular Ca2+ is elevated using liposomes as a vehicle, evoked ACh release can occur in the absence of Ca2+ entry via Ca2+ channels.

Effects of lymphokines and mitogens on a histamine derivative-induced intracellular calcium mobilization and inositol phosphate production

Histamine trifluoromethyl-toluidine derivative (HTMT), a novel immunosuppressive agent, stimulates H1, H2 and HTMT receptors in lymphocytes. HTMT receptors are different from the classical H1, H2 or H3 receptors. Stimulation of HTMT receptors results in increased intracellular concentrations of calcium ([Ca2+]i) and inositol phosphate (IP) in human peripheral blood lymphocytes. In the present study, we investigated the effects of lymphokines [interleukin-4 (IL-4), interleukin-2 (IL-2)] and other pharmacologic agents [lipopolysaccharide (LPS), phorbol 12-myristate 13-acetate (PMA)] on HTMT-induced Ca2+ and IP responses in non-rosetted cells. HTMT caused enhanced [Ca2+]i and IP responses when the cells were pretreated with IL-4. The effects of IL-4 were concentration dependent and became maximal after the cells were incubated with IL-4 for 48 hr. Inhibitors of protein synthesis, but not of RNA synthesis, blocked the effects of IL-4 on HTMT-induced responses. LPS was more potent than IL-4 in augmenting CA2+ mobilization induced by HTMT. However, the effects of LPS were not altered by inhibitors of either protein synthesis or RNA transcription. This indicated that LPS may act differently than IL-4 on the HTMT response. IL-2 and PMA did not affect HTMT-induced [Ca2+]i and IP responses. The effects of IL-4 and LPS were agonist specific. They did not affect the Ca2+ mobilization induced by PAF. The data indicate that the response to HTMT can be regulated by IL-4 and LPS. Although the in vivo importance of these receptors is not yet clear, the receptor is likely a contributor to immune and/or inflammatory regulation.

A metastable state of high surface activity produced by sonication of phospholipids

Sonication of phosphatidylcholine dispersions generates a metastable high energy assembly of molecules, the existence of which is revealed by its conspicuous surface activity. Freshly sonicated liposome dispersions release molecules to the air/water interface at rates sufficient to produce a close-packed monolayer within minutes. In contrast, monolayers at the surface of multilamellar and extruded vesicles take hours to form. The highly surface active species appears within the first few minutes of sonication, long before a major reduction in turbidity occurs, and accumulates over the course of a few hours of sonication. It disappears upon exhaustive sonication, extrusion, addition of extruded vesicles, or, more slowly, simply on standing. Tests for extraneous substances in the lipids before as well as after sonication revealed amounts of degradation products too small to represent the observed surfactant. Direct evidence that the metastable aggregate releases intact phospholipids was provided by a novel procedure to characterize monolayer composition by comparing surface tension with surface potential, both as a function of surface density. Centrifugation and gel filtration chromatography indicate that the surface activity is associated with a particle of diameter larger than a lysophosphatidylcholine micelle but not larger than limit sonicated vesicles. The metastable material appears to be lipid molecules in other than the normal stable vesicular state, perhaps an incompletely closed vesicle, one in which the inner and outer monolayers have not equilibrated, or possibly a micellar form.

Fragmentation into small vesicles of dioleoylphosphatidylcholine bilayers during freezing and thawing

Multilayered liposomes of some phosphatidylcholines progressively fragment into small vesicles when the electrolyte solution in which they are suspended is subjected to successive cycles of freezing and thawing. The fragmentation process, routinely monitored by absorbance measurements and verified by electron microscopy and dynamic light scattering, involves bilayer breakage and resealing. After 10 cycles of freezing and thawing in 0.1 M electrolyte solution, the result is a population of vesicles smaller than 200 nm diameter. Sucrose, a common cryoprotectant, completely inhibits fragmentation. Fragmentation is absolutely dependent upon the presence of an electrolyte. Those electrolytes most effective in promoting liposome fragmentation have large freezing point depressions and corresponding high solubilities at the freezing point. This, coupled with the observation that saturating concentrations of electrolyte are less effective than 0.1 M solutions indicates that an essential stage in the fragmentation process is osmotic extraction of water from the vesicles, i.e., ice formation in the external phase leads to a progressive increase in the electrolyte concentration of the residual external solution, which, in turn, dehydrates the vesicle. In addition, for maximal fragmentation, the minimum temperature must be at least as low as the solute eutectic temperature. Particular physical properties of the bilayer are also important, for dioleoyl and diphytanoyl derivatives are much more susceptible to fragmentation than are other phosphatidylcholines, and inclusion of 50 mol% cholesterol in dioleoylphosphatidylcholine completely inhibits membrane breakup. This system provides insight into mechanisms of freezing damage to membranes and may also offer a very simple and rapid assay for biological cryoprotectants.

A histamine derivative increases intracellular calcium mobilization and oxidative metabolism in HL-60 cells

Past work in our laboratory has shown that a derivative of histamine, histamine-trifluoromethyl-toluidide (HTMT), has surprising tissue specificity on lymphocytes and can produce remarkable immunosuppression. This study focuses on the effects of HTMT on Ca2+ mobilization and oxidative metabolism in undifferentiated and DMSO-differentiated HL-60 cells. HTMT caused two phases of increases in intracellular calcium concentrations ([Ca2+]i) in HL-60 cells. The responses were dose dependent, with similar EC50 values (1.7 x 10(-5) M for undifferentiated and 1.5 x 10(-5) M for differentiated cells). The increase in [Ca2+]i in differentiated cells was much greater than in undifferentiated cells. The maximum responses were observed after the undifferentiated cells were incubated with DMSO for 7 days. The increase in [Ca2+]i induced by HTMT in both types of cells was competitively antagonized by high concentrations of histamine but not by classic histamine receptor antagonists (H1, H2, or H3). The inhibitory effects of histamine on [Ca2+]i accumulation in differentiated cells were partially reversed by histamine H2 receptor antagonist ranitidine, whereas in undifferentiated cells, the effects of histamine on Ca2+ mobilization were not affected by ranitidine. Other cAMP elevating agents did not inhibit increases in [Ca2+]i in undifferentiated cells but did affect [Ca2+]i in differentiated cells. The enhanced response in [Ca2+]i mobilization after differentiation of HL-60 cells appeared to be the result of an increase in the expression/function of receptors for HTMT. One interesting feature of this regulation was the fact that cAMP per se did not regulate HTMT induced Ca2+ mobilization in undifferentiated cells but inhibited the mobilization in differentiated cells. HTMT caused the generation of reactive oxygen species in both undifferentiated and differentiated HL-60 cells as measured by chemoluminescence and the levels of generation correlated with the mobilization of [Ca2+]i. In addition, the EC50s for the HTMT induced calcium mobilization and the generation of reactive oxygen species were similar, as was the case for histamine induced inhibition (Ki) in both cell types. The data imply a second messenger role for Ca2+ in HTMT induced neutrophil activation.

Cyclic AMP is not a direct regulator of calcium flux and hydrolysis of phosphoinositides in human lymphocytes

The regulatory effects of adenosine 3',5'-cyclic monophosphate (cAMP) on Ca2+ flux and phosphatidylinositol (PI) turnover in human lymphocytes were studied. cAMP did not affect the intracellular accumulation of Ca2+ induced by phytohemagglutinin (PHA) and histamine-trifluoromethyl toluidide derivative (HTMT) in peripheral blood lymphocytes (PBL). In addition, cAMP also did not alter Ca2+ flux induced by PHA, anti-CD3, or PAF in T cells, or by anti-IgM and HTMT in non-rosetted cells. Similarly, cAMP did not inhibit IP accumulation induced by HTMT in PBL, anti-CD3 in T cells, and by anti-IgM or HTMT in non-rosetted cells. The only exception was the synthesis of IP induced by PHA in T cells that was inhibited by cAMP. Furthermore, prolonged treatment of T cells with cholera toxin inhibited Ca2+ accumulation in response to CD3. The degree of inhibition of Ca2+ and IP responses was not proportional to the levels of intracellular cAMP generated.

Effects of histamine-trifluoromethyl-toluidide derivative (HTMT) on intracellular calcium in human lymphocytes

We have studied the effects of histamine trifluoromethyl-toluidide derivatives on calcium mobilization in human peripheral blood lymphocytes using spectrofluorometric analysis. HTMT (compound 1) induced two phases of increase in intracellular calcium concentration--a rapid intracellular calcium concentration peak (10-60 sec), partial recovery (1-3 min) and a sustained moderate elevation that persisted for more than 5 min. The EC50 value was 1.9 X 10(-5) M. Pretreatment of lymphocytes with the agonist resulted in receptor desensitization that recovered after 15 min when the cells were drug free. The presence of extracellular ethylene glycol bis(beta-aminoethyl ether)N,N'-tetraacetic acid did not abrogate the early phase of the calcium rise, suggesting that the calcium appearing in the cytosol during the early phase was derived from intracellular stores. The increase in intracellular calcium concentration by this compound was competitively antagonized by high concentrations of histamine but not by classic histamine receptor antagonists (H1, H2 or H3). Other cyclic AMP elevating agents, with the exception of prostaglandin E2, did not affect the increase in calcium levels induced by compound 1. Compound 1 caused phosphatidylinositol metabolism resulting in inositol phosphate production, suggesting that inositol triphosphate may be the second messenger for the mobilization of intracellular Ca2+ by compound 1. The data imply a specific binding site for histamine trifluoromethyl toluidide derivative on lymphocytes that is different than the classic H1, H2 or H3 receptors.

Dissociation of cimetidine effects on inotropic and chronotropic action in cardiac anaphylaxis

The changes of heart rate (HR) and dP/dtmax elicited by challenging the sensitized heart and by a bolus injection of histamine in the presence of cimetidine were observed. The results showed that cimetidine did not completely inhibit the positive chronotropic effect in cardiac anaphylaxis. The increase in HR elicited by exogenous histamine on sensitized heart was completely abolished. Cimetidine inhibited the positive inotropic and chronotropic effect of histamine on normal heart in a dose-dependent manner. It is suggested either an H2 receptor subtype or concomitant with the release of histamine, other mediators eliciting positive chronotropism in cardiac anaphylaxis may exist.

Protective effects of histamine H1 and H2 antagonists, adenosine and hydrocortisone on cardiac anaphylaxis

Cardiac anaphylaxis was elicited in isolated working guinea pig hearts in the presence of the histamine receptor antagonists pyrilamine and cimetidine, adenosine or hydrocortisone. Histamine antagonists partially inhibited the occurrence of arrhythmias during cardiac anaphylaxis, but did not significantly antagonize the decrease in cardiac function. Adenosine used in combination with pyrilamine and cimetidine manifested an apparent anti-arrhythmic effect, however, the attenuation of cardiac function was still present. In the presence of hydrocortisone plus histamine antagonists, cardiac anaphylaxis, as expressed by arrhythmias and a decrease in cardiac function, was significantly inhibited. The results suggest that when histamine receptor antagonists are used in combination with hydrocortisone, a good protective effect on cardiac anaphylaxis can be achieved.