Expression and function of P-glycoprotein in rats with carbon tetrachloride-induced acute hepatic failure

Acute hepatic failure was induced experimentally in rats by intraperitoneal injection of 2.5 mL kg(-1) carbon tetrachloride (CCl4), and the effects on the expression and function of P-glycoprotein in the liver, kidney and brain were evaluated. The CCl4 injection significantly increased the indicators of hepatic function (glutamate oxaloacetate transaminase, glutamate pyruvate transaminase), but not of renal function (blood urea nitrogen, glomerular filtration rate). In rats with acute hepatic failure, the hepatic P-glycoprotein concentration increased 1.5-fold and the ATP concentration decreased to approximately 40% that in control rats. In contrast, P-glycoprotein concentrations in the kidney and brain and ATP concentrations in the kidney remained unchanged. The in-vivo P-glycoprotein function in these tissues was suppressed as evaluated by biliary and renal secretory clearances and brain distribution of rhodamine 123, a P-glycoprotein substrate. These findings suggest that factors other than P-glycoprotein concentration are involved in the systemic suppression of P-glycoprotein function in diseased rats. In Caco-2 cells, plasma collected from CCl4-treated rats exhibited a greater inhibitory effect on P-glycoprotein-mediated transport of rhodamine 123 than that from control rats, suggesting the accumulation of an endogenous P-glycoprotein substrate/inhibitor in the plasma of diseased rats. In fact, the plasma concentration of corticosterone, an endogenous P-glycoprotein substrate, increased 2-fold in CCl4-treated rats compared with control rats. It was demonstrated that P-glycoprotein function is systemically suppressed in rats with CCl4-induced acute hepatic failure, not only in the target organ (liver), but also in other organs (kidney and brain), although the P-glycoprotein concentration remained unchanged in the kidney and brain, and increased in the liver. In the systemic suppression of the P-glycoprotein function in the diseased state, the alteration of plasma concentrations or components of endogenous P-glycoprotein-related compounds, such as corticosterone, would likely be involved.

Expression and function of P-glycoprotein in rats with glycerol-induced acute renal failure

The effect of glycerol-induced acute renal failure on P-glycoprotein expression and function was evaluated in rats. The in vivo function of P-glycoprotein was evaluated by measuring renal secretory and biliary clearance and brain distribution of rhodamine 123 (Rho-123), a P-glycoprotein substrate, under a steady-state plasma concentration. In acute renal failure rats, the P-glycoprotein level increased 2.5-fold in the kidney, but not in the liver and brain. In contrast, P-glycoprotein function in these tissues was suppressed. Interestingly, not only the renal but also the biliary clearance of Rho-123 was correlated with the glomerular filtration rate. In Caco-2 cells, plasma from renal failure rats exhibited a greater inhibitory effect on P-glycoprotein-mediated transport of Rho-123 than did plasma from control rats. In conclusion, P-glycoprotein function was systemically suppressed in acute renal failure, even though the level of P-glycoprotein remained unchanged or rather increased. This may be due to the accumulation of some endogenous P-glycoprotein substrates/modulators in the plasma in disease states.

Construction of HBV-specific ribozyme and its recombinant with HDV and their cleavage activity in vitro

AIM: To construct the recombinant of HDV cDNA and HBV-specific ribozyme gene by recombinant PCR in order to use HDV as a transporting vector carrying HBV-specific ribozyme into liver cells for inhibiting the replication of HBV.

METHODS: We separately cloned the ribozyme (RZ) gene and recombinant DVRZ (comprising HDV cDNA and HBV-specific ribozyme gene) into the downstream of T7 promoter of pTAdv-T vector and studied the in vitro cleavage activity of their transcripts (rRZ, rDVRZ) on target RNA (rBVCF) from in vitro transcription of HBV C gene fragment(BVCF).

RESULTS: Both the simple (rRZ) and the recombinant ribozyme rDVRZ could efficiently catalyze the cleavage of target RNA (rBVCF) under different temperatures (37 °C, 42 °C and 55 °C) and Mg²⁺ concentrations (10 mmol/L, 15 mmol/L and 20 mmol/L) and their catalytic activity tended to increase as the temperature was rising. But the activity of rRZ was evidently higher than that of rDVRZ.

CONCLUSION: The recombinant of HDV cDNA and ribozyme gene had the potential of being further explored and used in gene therapy of HBV infection.

Ecdysteroid hormones and metabolites of the stone crab, Menippe mercenaria

The Y-organs of the xanthid crab Menippe mercenaria secrete the ecdysteroids, 3-dehydroecdysone (3DE) and lesser amounts of 3-dehydro (or 2-dehydro)-25-deoxyecdysone (3D25dE) in vitro. These ecdysteroids were identified by elution-time comparisons with authentic standards, mass spectrography, and, for 3D25dE, infrared spectrometry. Tissues were incubated 18 hr with [(3)H]3DE. Activities representing 3beta-reductase and 20-hydroxylase generally were present, evidenced by finding in the tissue/medium extract labeled ecdysone (E) and 20-hydroxyecdysone (20E). Labeled 3-dehydro-20-hydroxyecdysone (3D20E) also appeared to be present. Tissue blanks and hemolymph were devoid of activity. Muscle was low, hypodermis was intermediate, and hindgut and gonads were high in activity of the enzymes. Consistent with the presence of these enzymes in peripheral tissues, ecdysteroid products identified in the hemolymph were 20E, 3D20E, and 25-deoxy-20-hydroxyecdysone (25d20E; ponasterone A). Structures of 20E and 3D20E were confirmed by co-elution with authentic standards in high-performance liquid chromatography (HPLC), co-elution of derivatives in gas chromatography, and mass spectroscopy. Ponasterone A (identified by HPLC co-elution with the standard), like 20E is present in the hemolymph in prominent amounts. These data indicate that Menippe, among crustaceans thus far studied, secretes a unique combination of ecdysteroid hormones, namely, a 3- (or 2-) oxo compound and a 25-deoxy compound. This represents a different kind of branch point from 5beta-diketol in ecdysteroid biosynthesis, in which the intermediate, 5beta-ketodiol is bypassed. A result is the joint appearance in the circulation of the hormones, 20E and ponasterone A, which in other species are singly prominent.

Characterization of Staphylococcus aureus cell wall glycan strands, evidence for a new beta-N-acetylglucosaminidase activity

Using sequential digestion with the glycyl-glycine endopeptidase lysostaphin followed by the pneumococcal N-acetylmuramyl-L-alanine amidase (amidase), the glycan strands of the peptidoglycan of Staphylococcus aureus were purified and analyzed by a combination of reverse-phase-high pressure liquid chromatography (HPLC) and mass spectrometry. Reverse-phase-HPLC resolved the glycan strands to a family of major peaks, which represented oligosaccharides composed of repeating disaccharide units (N-acetylglucosamine-[beta-1, 4]-N-acetylmuramic acid) with different degrees of polymerization and terminating with N-acetylmuramic acid residues at the reducing ends. The method allowed separation of strands up to 23-26 disaccharide units with a predominant length between 3 and 10 and an average degree of polymerization of approximately 6. Glycan strands with a higher degree of polymerization (>26 disaccharide units) represented 10-15% of the total UV absorbing glycan material. A unique feature of the staphylococcal glycan strands was the presence of minor satellite peaks that were present throughout the HPLC elution profile eluting either just prior or shortly after the major oligosaccharide peaks. A number of observations including mass spectrometric analysis suggest that the satellites are the products of an N-acetylglucosaminidase activity that differs from the atl gene product and that appears to be involved with modification of the glycan strand structure.

Evaluation of charge derivatization of a proteolytic protein digest for improved mass spectrometric analysis: de novo sequencing by matrix-assisted laser desorption/ionization post-source decay mass spectrometry

A simple mass spectrometric method to sequence a recombinant phosphoenolpyruvate carboxykinase of known structure and a novel variant of unknown structure isolated from Anaerobiospirillum succiniciproducens and Actinobacillus succinogenes 130Z, respectively, was evaluated. The proteolytic digests of the proteins were each chemically derivatized at the N-terminus by addition of a tris(trimethoxyphenyl)phosphoniumacetyl (TMPP(+)-Ac) group to produce peptides with a fixed positive charge. The derivatized digests were then partially separated by reversed-phase high-performance liquid chromatography. The fractions collected were subjected to matrix-assisted laser desorption/ionization post-source decay (MALDI/PSD) mass spectrometric analysis. The resulting spectra are sufficiently simple to allow the sequence to be read directly without extensive interpretation. This is in contrast to spectra of underivatized peptides obtained by MALDI/PSD or conventional tandem mass spectrometry, where full sequence interpretation can be challenging. Aided with a set of very simple established rules, it was shown that the sequence of TMPP(+)-Ac derivatives can be derived strictly from predictable fragment ion series. In most cases, this is sufficient to determine extensive, unambiguous, peptide sequences de novo. The partial sequence (35%) of the unknown phosphoenolpyruvate carboxykinase from Actinobacillus succinogenes 130Z was obtained entirely by the mass spectrometric method evaluated here, which provided the basis for evaluating homology and for the design of oligonucleotide probes for cloning the corresponding gene.

Serum antibodies to Balamuthia mandrillaris, a free-living amoeba recently demonstrated to cause granulomatous amoebic encephalitis

Free-living amoebae cause three well-defined disease entities: a rapidly fatal primary meningoencephalitis, a chronic granulomatous amoebic encephalitis (GAE), and a chronic amoebic keratitis. GAE occurs in immunocompromised persons. Recently, another type of free-living amoeba, Balamuthia mandrillaris, has been shown to cause GAE. The finding that this amoeba has caused infection in some healthy children has raised the possibility that humans may lack immunity to B. mandrillaris. Human serum was examined for the presence of surface antibodies specific for this amoeba by immunofluorescence. Sera from adults contained titers of 1/64-1/256 of anti-B. mandrillaris antibodies (IgM and IgG classes), which did not cross-react with other amoebae. Cord blood contained very low antibody levels, but levels similar to those in adults were seen in serum of 1- to 5-year-old children.

Protein sequencing by matrix-assisted laser desorption ionization-postsource decay-mass spectrometry analysis of the N-Tris(2,4,6-trimethoxyphenyl)phosphine-acetylated tryptic digests

We have recently reported a simple procedure by which low picomole quantities of peptides can be modified to the corresponding N-Tris(2, 4,6-trimethoxyphenyl)phosphonium-acetyl (TMPP-Ac) derivatives (Z. H Huang, J. Wu, D. A. Gage, and J. T. Watson, Anal. Chem. 69, 137-144, 1997). This modification significantly facilitates sequence interpretation by providing exclusively N-terminal product ions (mainly a-type ions) in the fast-atom bombardment-MS/MS and matrix-assisted laser desorption ionization-postsource decay(MALDI-PSD)-MS spectra. The TMPP-Ac derivatization approach has been extended now for the direct derivatization of tryptic digests originating from 1-5 microg of proteins with molecular weights from 10-120 kDa. Our new procedure involves tryptic digestion in aqueous solution buffered to pH 8-8.2 with phosphate or Tris-HCl, followed by reaction with TMPP-acetic acid N-hydroxysuccinimide ester (TMPP-AcOSu bromide, 2-4 nmol reagent/microg protein, rt, 20 min) to provide N-terminally derivatized products, while the epsilon-NH2 groups in lysine remain unchanged. The resultant derivatized peptide mixture or its partially separated HPLC fractions are subsequently analyzed by MALDI-PSD-MS using 0.5- to 1-pmol aliquots, giving rise to product ion spectra that are easily interpretable. As there is no need for material transfer and change of buffer media, the tandem enzymatic-chemical reaction/MS analysis process is usually carried out with very high throughput (digestion, 1 h; reaction, 1/3 h; HPLC, 1 h; MALDI-PSD, 3-4 fragments/h). This procedure will be of potential use for obtaining sequence information directly from mixtures or as an adjunct of peptide mass mapping to provide protein identification with high confidence.

Localization of receptors for luteinizing hormone/chorionic gonadotropin in neural retina

Although the expression of the luteinizing hormone (LH)/human chorionic gonadotropin (CG) receptor gene has been traditionally thought to be restricted to gonadal tissue, recent studies have shown that LH/CG receptors are present in many regions of the central nervous system (CNS), as well as in peripheral tissues. We now report the characterization of LH/CG receptor gene expression in the neural retina, a component of the CNS. Transcript levels in the retina are approximately equal to levels present in the cerebral cortex, but are at least 100 fold lower than the levels in testis. The density of LH/CG receptor transcripts, receptor protein and 125I-CG binding is the highest in the photoreceptor cells and then decreased throughout the inner retina. Our study is the first to demonstrate the presence of LH/CG receptors in the neural retina. This finding raises the possibility that photoreceptor cells have the potential to mount cellular responses to LH/CG that may impact on visual processing, and poses an intriguing connection to the proposed role of gonadotropins in the progression of proliferative retinopathy.

Stimulation of p38 phosphorylation and activity by arachidonic acid in HeLa cells, HL60 promyelocytic leukemic cells, and human neutrophils. Evidence for cell type-specific activation of mitogen-activated protein kinases

Although it is well appreciated that arachidonic acid, a second messenger molecule that is released by ligand-stimulated phospholipase A2, stimulates a wide range of cell types, the mechanisms that mediate the actions of arachidonic acid are still poorly understood. We now report that arachidonic acid stimulated the appearance of dual-phosphorylated (active) p38 mitogen-activated protein kinase as detected by Western blotting in HeLa cells, HL60 cells, human neutrophils, and human umbilical vein endothelial cells but not Jurkat cells. An increase in p38 kinase activity caused by arachidonic acid was also observed. Further studies with neutrophils show that the stimulation of p38 dual phosphorylation by arachidonic acid was transient, peaking at 5 min, and was concentration-dependent. The effect of arachidonic acid was not affected by either nordihydroguaiaretic acid, an inhibitor of the 5-, 12-, and 15-lipoxygenases or by indomethacin, an inhibitor of cyclooxygenase. Arachidonic acid also stimulated the phosphorylation and/or activity of the extracellular signal-regulated protein kinase and of c-jun N-terminal kinase in a cell-type-specific manner. An examination of the mechanisms through which arachidonic acid stimulated the phosphorylation/activity of p38 and extracellular signal-regulated protein kinase in neutrophils revealed an involvement of protein kinase C. Thus, arachidonic acid stimulated the translocation of protein kinase C alpha, betaI, and betaII to a particulate fraction, and the effects of arachidonic acid on mitogen-activated protein kinase phosphorylation/activity were partially inhibited by GF109203X, an inhibitor of protein kinase C. This study is the first to demonstrate that a polyunsaturated fatty acid causes the dual phosphorylation and activation of p38.

Charge derivatization of peptides for analysis by mass spectrometry

The analysis of peptide derivatives by fast atom bombardment, liquid secondary-ionization mass spectrometry, plasma desorption, electrospray ionization, and matrix-assisted laser desorption/ionization is reviewed. The fragmentation patterns of peptides and of charge-derivatized peptides are compared, and the proposed fragment ion structures are summarized. A variety of derivatization approaches and the distinguishing features of mass spectra produced from these derivatives are described. The most promising derivatization approaches are evaluated, and the strengths and limitations of these approaches are discussed.

Shenjincao (Palhinhaea cernua) injection for treatment of experimental silicosis of rats

Shenjincao injection is a traditional Chinese medicine prepared from Palhinhaea cernua (L.) A. Franco et Vasc. by ultrafiltration. Its anti-silicosis action has been investigated both as a prophylactic and for treatment of the disease. Wistar rats were injected intra-tracheally with quartz dust and then divided randomly into groups-treatment and control prophylactic groups and treatment and control disease groups. After five days or eight weeks, respectively, the silica-exposed rats of the two treatment groups were injected intraperitoneally three times a week with shenjincao injection, dose 2.0 mL, for five weeks or 11 weeks, respectively. The rats were then dissected, and the ceruloplasmin content of the serum and the fresh weight, dry weight, collagen content and pathological grade of the lungs were measured. Compared with the corresponding exposed control groups for the same treatment periods the values of these parameters were reduced by 62.8% to 30.7% for rats in the prophylactic treatment group (P < 0.01 for all) and by 50.8% to 30.2% for the diseased group (P < 0.01 for all). The values for the disease-treatment group were also reduced by 37.9% to 25.9% compared with values for the exposed control group before treatment (P < 0.01 or P < 0.05). The effective coefficients for prophylactic treatment were 82.6% to 56.0%; for disease treatment they were 68.8% to 39.8%. These results show that shenjincao injection is efficacious against experimental silicosis not only when used prophylactically but also when used to treat the disease.

Conversion of forskolin-insensitive to forskolin-sensitive (mouse-type IX) adenylyl cyclase

Forskolin potently activates all cloned mammalian adenylyl cyclases except type IX by interacting with two homologous cytoplasmic domains (C1 and C2) that form the catalytic core. A mutational analysis of the IIC2 protein (C2 domain from type II adenylyl cyclase) and forskolin analogs suggests that Ser942 interacts with the 7-acetyl group of forskolin. The C1/C2 complex has only one forskolin, one ATP, and one binding site for the alpha subunit of the G protein that stimulates adenylyl cyclase (Gsalpha) and its structure may be modeled using the three-dimensional structure of (IIC2/forskolin)2. The Ser942 mutation defines which forskolin in the (IIC2/forskolin)2 structure exists in C1/C2 complex. Thus, the forskolin-binding site is close to the Gsalpha-binding site but distal (15-20A) from the catalytic site. Mutation from Leu912 of IIC2 protein to tyrosine or alanine severely reduces Gsalpha activation and completely prevents forskolin activation. The corresponding residue of Leu912 is Tyr1082 at type IX isoform of adenylyl cyclase. Similar to recombinant type IX enzyme, soluble adenylyl cyclase derived from mouse-type IX adenylyl cyclase is sensitive to Gsalpha activation but not to forskolin. Changing Tyr1082 to leucine makes soluble type IX adenylyl cyclase forskolin-responsive.

Salinity promotes accumulation of 3-dimethylsulfoniopropionate and its precursor S-methylmethionine in chloroplasts

Wollastonia biflora (L.) DC. plants accumulate the osmoprotectant 3-dimethylsulfoniopropionate (DMSP), particularly when salinized. DMSP is known to be synthesized in the chloroplast from S-methylmethionine (SMM) imported from the cytosol, but the sizes of the chloroplastic and extrachloroplastic pools of these compounds are unknown. We therefore determined DMSP and SMM in mesophyll protoplasts and chloroplasts. Salinization with 30% (v/v) artificial seawater increased protoplast DMSP levels from 4.6 to 6.0 mumol mg-1 chlorophyll (Chl), and chloroplast levels from 0.9 to 1.9 mumol mg-1 Chl. The latter are minimum values because intact chloroplasts leaked DMSP during isolation. Correcting for this leakage, it was estimated that in vivo about one-half of the DMSP is chloroplastic and that stromal DMSP concentrations in control and salinized plants are about 60 and 130 mM, respectively. Such concentrations would contribute significantly to chloroplast osmoregulation and could protect photosynthetic processes from stress injury. SMM levels were measured using a novel mass-spectrometric method. About 40% of the SMM was located in the chloroplast in unsalinized W. biflora plants, as was about 80% in salinized plants; the chloroplastic pool in both cases was approximately 0.1 mumol mg-1 Chl. In contrast, > or = 85% of the SMM was extrachloroplastic in pea (Pisum sativum L.) and spinach (Spinacia oleracea L.), which lack DMSP. DMSP synthesis may be associated with enhanced accumulation of SMM in the chloroplasm.

Effects of 5-oxo-6,8,11,14-eicosatetraenoic acid on expression of CD11b, actin polymerization, and adherence in human neutrophils

Human neutrophils contain a highly specific dehydrogenase that converts 5-hydroxy-6,8,11,14-eicosatetraenoic acid to 5-oxo-6,8,11,14-eicosatetraenoic acid (5-oxo-ETE). 5-Oxo-ETE is a potent stimulator of calcium mobilization, chemotaxis, and aggregation in these cells and has similar effects on eosinophils. The primary objectives of the current study were to determine whether this compound could increase the surface expression of integrins and stimulate actin polymerization in neutrophils. 5-Oxo-ETE stimulated the expression of CD11b and, to a lesser extent, CD11c, on neutrophils, but had no significant effects on the expression of CD11a, CD16 (Fc gammaRIII), or CD32 (Fc gammaRII). Surface expression of CD11b in response to 5-oxo-ETE was maximal after 12 min and remained constant thereafter. The EC50 for this response (50 nM) was lowered to 20 nM by preincubation of neutrophils with PMA. 5-Oxo-ETE (EC50, 10 nM) also rapidly stimulated actin polymerization in neutrophils, with a maximal response at 20 s. This response was blocked by pretreatment of neutrophils with the Gi protein inhibitor, pertussis toxin, and by homologous desensitization due to preincubation with 5-oxo-ETE. However, preincubation with leukotriene B4 or platelet-activating factor had no effect on the response of neutrophils to subsequent addition of 5-oxo-ETE. The adherence of neutrophils to plasma-coated plastic was also stimulated by 5-oxo-ETE with a time course similar to that for the surface expression of CD11b. Low concentrations of PMA (0.3 nM) enhanced this response. These results raise the possibility that 5-oxo-ETE could contribute to the infiltration of neutrophils into inflammatory sites.

Effects of 5-oxo-6,8,11,14-eicosatetraenoic acid on expression of CD11b, actin polymerization, and adherence in human neutrophils

Human neutrophils contain a highly specific dehydrogenase that converts 5-hydroxy-6,8,11,14-eicosatetraenoic acid to 5-oxo-6,8,11,14-eicosatetraenoic acid (5-oxo-ETE). 5-Oxo-ETE is a potent stimulator of calcium mobilization, chemotaxis, and aggregation in these cells and has similar effects on eosinophils. The primary objectives of the current study were to determine whether this compound could increase the surface expression of integrins and stimulate actin polymerization in neutrophils. 5-Oxo-ETE stimulated the expression of CD11b and, to a lesser extent, CD11c, on neutrophils, but had no significant effects on the expression of CD11a, CD16 (Fc gammaRIII), or CD32 (Fc gammaRII). Surface expression of CD11b in response to 5-oxo-ETE was maximal after 12 min and remained constant thereafter. The EC50 for this response (50 nM) was lowered to 20 nM by preincubation of neutrophils with PMA. 5-Oxo-ETE (EC50, 10 nM) also rapidly stimulated actin polymerization in neutrophils, with a maximal response at 20 s. This response was blocked by pretreatment of neutrophils with the Gi protein inhibitor, pertussis toxin, and by homologous desensitization due to preincubation with 5-oxo-ETE. However, preincubation with leukotriene B4 or platelet-activating factor had no effect on the response of neutrophils to subsequent addition of 5-oxo-ETE. The adherence of neutrophils to plasma-coated plastic was also stimulated by 5-oxo-ETE with a time course similar to that for the surface expression of CD11b. Low concentrations of PMA (0.3 nM) enhanced this response. These results raise the possibility that 5-oxo-ETE could contribute to the infiltration of neutrophils into inflammatory sites.

[Clinical observation on treatment of infantile cholestatic hepatitis syndrome by rhubarb]

OBJECTIVE

To evaluate the role of Rhubarb in treating infantile cholestatic hepatitis syndrome (IHS).

METHODS

Forty-four patients of the treatment group were treated with Rhubarb per os and/or duodenal infusion, 20 cases of the control group were treated with general liver protecting therapy such as inosine, vitamin C and glucose. Serum bilirubin, alanine transaminase (ALT) and gamma-glutamyl transferase (gamma-GT) level, bilirubin in duodenal juice and liver size were observed before and after treatment.

RESULTS

In the treatment group, 18 cases were markedly effective, 21 effective, 3 ineffective and 2 were deteriorated, while in the control group, the respective number were 0, 4, 13 and 3.

CONCLUSIONS

Rhubarb was a markedly effective in cholagoging and abating of jaundice, it could promote the recovery of liver function, dredge the cholestasis in cholangiole and micro-cholangiole so as to promote the bile secretion.

Three discrete regions of mammalian adenylyl cyclase form a site for Gsalpha activation

The interaction between the alpha subunit of G protein Gs (Gsalpha) and the two cytoplasmic domains of adenylyl cyclase (C1 and C2) is a key step in the stimulation of cAMP synthesis by hormones. Mutational analysis reveals that three discrete regions in the primary sequence of adenylyl cyclase affect the EC50 values for Gsalpha activation and thus are the affinity determinants of Gsalpha. Based on the three-dimensional structure of C2.forskolin dimer, these three regions (C2 alpha2, C2 alpha3/beta4, and C1 beta1) are close together and form a negatively charged and hydrophobic groove the width of an alpha helix that can accommodate the positively charged adenylyl cyclase binding region of Gsalpha. Two mutations in the C2 alpha3/beta4 region decrease the Vmax values of Gsalpha activation without an increase in the EC50 values. Since these three regions are distal to the catalytic site, the likely mechanism for Gsalpha activation is to modulate the structure of the active site by controlling the orientation of the C2 alpha2 and alpha3/beta4 structures.

N-6 and n-3 polyunsaturated fatty acids stimulate translocation of protein kinase Calpha, -betaI, -betaII and -epsilon and enhance agonist-induced NADPH oxidase in macrophages

The polyunsaturated fatty acids (PUFA), arachidonic acid (AA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were poor inducers of oxygen-dependent respiratory activity (chemiluminescence) in human monocytes and macrophages, but markedly enhanced the response to the tripeptide, N-formylmethionyl-leucyl-phenylalanine. The effects of these fatty acids were seen at concentrations of 1 microg/ml. A similar enhancement was seen with PMA, a stimulus that acts on protein kinase C (PKC), or calcium ionophore (A23187), which increases intracellular calcium, suggesting that the effect of the fatty acids was post-surface receptor binding. HL-60 cells, differentiated to macrophage-like cells by culture in the presence of vitamin D3, were similarly affected by the fatty acids. In experiments in which the time of pre-exposure of the monocytes to PUFA was varied, it was found that the priming effect induced by AA, EPA and DHA was maximal at 5 min. The ability of these fatty acids to synergize with other agonists was completely lost if the fatty acids were either methylated or oxidized to the hydro and hydroperoxy derivatives. Saturated fatty acids were inactive. Western blot analysis demonstrated that the PUFA induced the translocation of PKCalpha, -betaI, -betaII and -epsilon isoenzymes to a particulate fraction. The synergistic response between fatty acids and A23187 was completely inhibited by pretreating the cells with a PKC inhibitor, GF-109203X, or by pretreatment of monocytes with PMA for 18 h, to deplete PKC levels. From these investigations it is evident that PUFA prime macrophages, causing increased/synergistic oxidative respiratory burst activity to other stimuli and that this priming is dependent on PKC translocation and activation.

Novel independent and synergistic regulation of gonadotropin-alpha subunit gene by luteinizing hormone/human choriogonadotropin and gonadotropin releasing hormone in the alphaT3-1 gonadotrope cells

The alphaT3-1 cells are immortalized anterior pituitary gonadotropes which express gonadotropin-alpha subunit gene. These cells contain receptors for gonadotropin releasing hormone (GnRH) as well as for luteinizing hormone (LH) which can also bind human choriogonadotropin (hCG). Like GnRH, LH and hCG can upregulate the expression of gonadotropin-alpha subunit gene. While 0.1-1.0 ng/ml hCG can upregulate, higher concentrations have no effect. However, these higher hCG concentrations can act in a synergistic manner with GnRH to increase the steady state mRNA and protein levels of gonadotropin-alpha subunit. The synergism between hCG and GnRH was mimicked by LH but not by other hormones in the glycoprotein hormone family or alpha or beta subunits of hCG, suggesting that the synergism is hormone specific and requires the conformation of native hormone. The hCG induced increase in gonadotropin-alpha subunit mRNA levels was due to a significant increase in the half-life of gonadotropin-alpha subunit transcripts from 7.8 +/- 1.0 h in the controls to 16.5 +/- 3.8 h after treatment with hCG. The GnRH induced increase in gonadotropin-alpha subunit mRNA levels was due to both a significant increase in the half-life to 26.2 +/- 3.0 h as well as a significant increase in the transcription rate of the gene (159.0 +/- 7.7% of the control). A greater increase in gonadotropin-alpha subunit mRNA levels following a combined treatment with GnRH and hCG was due to a further increase in half-life to 37.6 +/- 3.1 h as well as a greater increase in the transcription rate of the gene (295.1 +/- 24.2% of the control) as compared to the treatment with GnRH alone. In summary, we conclude that LH and hCG can independently and synergistically act with GnRH to increase the expression of gonadotropin-alpha subunit gene by transcriptional as well as by post-transcriptional mechanisms in alphaT3-1 cells. These effects may be important for the increase of LH levels during the preovulatory surge.

Structural characterization of peptidoglycan muropeptides by matrix-assisted laser desorption ionization mass spectrometry and postsource decay analysis

In this study we report the development of matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS)-based methods for the structural characterization of muropeptides derived from peptidoglycan. Prior to analysis, peptidoglycan samples were subjected to enzymatic digestion with muramidase and the resulting muropeptides were purified by HPLC. A new matrix, 5-chloro-2-mercaptobenzothiazole, was employed for the MALDI-MS analysis. The results have demonstrated that sub-picomole to femtomole detection can be achieved in both positive mode and negative mode, allowing unambiguous determination of the molecular masses of monomeric and oligomeric muropeptides. Structural information from monomeric muropeptides was obtained by further postsource decay (PSD) analysis. Fragmentation patterns in positive mode and negative mode PSD were complementary for the elucidation of the peptide chain sequence. Lysostaphin digestion was also incorporated with MALDI mass mapping analysis for determination of peptide chain cross-linking patterns of muropeptide oligomers from Staphylococcus aureus strains.

The conserved asparagine and arginine are essential for catalysis of mammalian adenylyl cyclase

Mammalian adenylyl cyclases have two homologous cytoplasmic domains (C1 and C2), and both domains are required for the high enzymatic activity. Mutational and genetic analyses of type I and soluble adenylyl cyclases suggest that the C2 domain is catalytically active and the C1 domain is not; the role of the C1 domain is to promote the catalytic activity of the C2 domain. Two amino acid residues, Asn-1025 and Arg-1029 of type II adenylyl cyclase, are conserved among the C2 domains, but not among the C1 domains, of adenylyl cyclases with 12 putative transmembrane helices. Mutations at each amino acid residue alone result in a 30-100-fold reduction in Kcat of adenylyl cyclase. However, the same mutations do not affect the Km for ATP, the half-maximal concentration (EC50) for the C2 domain of type II adenylyl cyclase to associate with the C1 domain of type I adenylyl cyclase and achieve maximal enzyme activity, or the EC50 for forskolin to maximally activate enzyme activity with or without Gsalpha. This indicates that the mutations at these two residues do not cause gross structural alteration. Thus, these two conserved amino acid residues appear to be crucial for catalysis, and their absence from the C1 domains may account for its lack of catalytic activity. Mutations at both amino acid residues together result in a 3,000-fold reduction in Kcat of adenylyl cyclase, suggesting that these two residues have additive effects in catalysis. A second site suppressor of the Asn-1025 to Ser mutant protein has been isolated. This suppressor has 17-fold higher activity than the mutant and has a Pro-1015 to Ser mutation.

Altered responses of human macrophages to lipopolysaccharide by hydroperoxy eicosatetraenoic acid, hydroxy eicosatetraenoic acid, and arachidonic acid. Inhibition of tumor necrosis factor production

The regulation of allergic and autoimmune inflammatory reactions by polyunsaturated fatty acids and their metabolic products (eicosanoids) continues to be of major interest. Our data demonstrate that arachidonic acid 5,8,11,14-eicosatetraenoic acid (20:4n-6) and its hydroxylated derivatives 15(s)-hydroxy-5,8,11,13-eicosatetraenoic acid (15-HETE) and 15(s)-hydroperoxy-5,8,11,13-eicosatetraenoic acid (15-HPETE) regulate agonist-induced tumor necrosis factor alpha (TNF) production, a cytokine that plays a role in inflammatory diseases. Although 20:4n-6 and 15-HETE caused a reduction in production of TNF in mononuclear leukocytes stimulated with phytohaemagglutinin, pokeweed mitogen, concanavalin A, and Staphylococcus aureus, 15-HPETE was far more active. 15-HPETE was also found to dramatically depress the ability of bacterial lipopolysaccharide to induce TNF production in monocytes and the monocytic cell line Mono Mac 6. These fatty acids depressed the expression of TNF mRNA in Mono Mac 6 cells stimulated with LPS; 15-HPETE was fivefold more active than 20:4n-6 and 15-HETE. While 15-HPETE treatment neither affected LPS binding to Mono Mac 6 cells nor caused a decrease in CD14 expression, the fatty acid significantly reduced the LPS-induced translocation of PKC (translocation of alpha, betaI, betaII, and epsilon isozymes), suggesting that 15-HPETE acts by abrogating the early signal transduction events. The findings identify another molecule that could form the basis for development of antiinflammatory pharmaceuticals.

Inhibition of stimulus-induced endothelial cell intercellular adhesion molecule-1, E-selectin, and vascular cellular adhesion molecule-1 expression by arachidonic acid and its hydroxy and hydroperoxy derivatives

Localized adhesion of peripheral blood leukocytes to the endothelial lining is essential for their exit from the blood under both physiological and pathological conditions. The establishment, development, and resolution of the inflammatory response is regulated by an array of mediators, many of which remain to be categorized. These include arachidonic acid (20:4n-6) and its hydroperoxy (HPETE) and hydroxy (HETE) derivatives, which are released during inflammation. The data show that human umbilical vein endothelial cells, pretreated with these fatty acids, have a reduced ability to be stimulated by tumor necrosis factor-alpha (TNF-alpha) for enhanced neutrophil and monocyte adhesion; the order of inhibitory activity being 15-HPETE > 15-HETE > 20:4 (n-6). This fatty acid-induced inhibitory activity was reflected in the ability of the mediators to decrease the TNF-alpha-induced expression of the following endothelial adhesion molecules: intercellular adhesion molecule-1 (ICAM-1), E-selectin, and vascular cell adhesion molecule-1 (VCAM-1), measured by both enzyme-linked immunosorbent assay and flow cytometric analysis. TNF-alpha-induced increased expression of ICAM-1, E-selectin, and VCAM-1 mRNA was significantly depressed by 15-HPETE. Constitutively expressed ICAM-1 and ICAM-1 mRNAs were unchanged by the fatty acids. The saturated fatty acid 20:0 and the methyl ester of 20:4(n-6) had no inhibitory activity. The binding of TNF-alpha to its receptors was not altered by these fatty acids. The fatty acids also inhibited the expression of ICAM-1 and E-selectin induced by phorbol 12-myristate 13-acetate, showing that inhibition occurred at a post-TNF-alpha receptor binding level. The 15-HPETE was found to inhibit the TNF-alpha-induced increase in adhesion molecule expression in the early stage of the incubation, but expression returned to normal after 18 hours. An effect of 15-HPETE on the early cell signaling system was demonstrated by the ability of this fatty acid to inhibit agonist-induced protein kinase C translocation.

A picomole-scale method for charge derivatization of peptides for sequence analysis by mass spectrometry

A highly activated ester containing a fixed positive charge, S-pentafluorophenyl [tris(2,4,6-trimethoxyphenyl)phosphonium]acetate bromide (TMPP-AcSC6F5 bromide), has been synthesized as a reagent for N-terminal modification of peptides. Stable in aqueous acetonitrile solution during extended storage, TMPP-AcSC6F5 bromide reacts with unprotected peptides through p-(dimethylamino)pyridine (DMAP)-promoted amidation in aqueous acetonitrile (15 min, ambient temperature) to form N-TMPP-Ac derivatives of peptides. These peptide derivatives are readily amenable to analysis by fast atom bombardment (FAB) and matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. Greater than 90% conversion has been observed in transforming low-nanomole quantities of analyte using molar ratios of 1:5:10 (peptide/reagent/ DMAP). For reactions at the picomole level a slightly modified stoichiometry, with molar ratios of 1:10:500, is employed. Owing to the high reaction efficiency and the tolerance to moderate excess reagent and base during analysis by FAB- and MALDI-MS, the reaction mixture containing the modified peptides can be analyzed directly in most cases, without sample cleanup. Examples of the preparation and analysis of a variety of N-TMPP-acetyl-peptides (TMPP-Ac-peptides) ranging from hexamers to 15-mers are given. Collisionally activated dissociation tandem mass spectrometry of TMPP-Ac-derivatives showed dominant a-type ions, accompanied by d- and c-type ions in some cases, allowing sequence determination to be made in a straightforward manner.

Human skin contains luteinizing hormone/chorionic gonadotropin receptors

Normal human skin contains a major 4.5 kb and several minor mRNA transcripts and a 66 kDa protein of luteinizing hormone (LH)/chorionic gonadotropin (hCG) receptors which are capable of binding exogenous 125I-hCG. The distribution of receptor transcripts and receptor protein are the highest in epidermis followed by hair follicles, sebaceous and sweat glands. LH/hCG receptors are co-localized with androgen receptors in all the skin appendages. These data are the first demonstration of skin containing LH/hCG receptors and would suggest that LH and hCG may regulate skin functions.

Two cytoplasmic domains of mammalian adenylyl cyclase form a Gs alpha- and forskolin-activated enzyme in vitro

Mammalian adenylyl cyclases have two homologous cytoplasmic domains (C1 and C2). The first cytoplasmic domain of type I enzyme (IC1) and the second cytoplasmic domain of type II enzyme (IIC2-delta 3, a construct in which 36 N-terminal amino acids of the C2 region are deleted) were expressed and purified to homogeneity. Alone, each had no adenylyl cyclase activity; however, mixing of the two domains in vitro resulted in Gs alpha- and forskolin-activated enzyme activity. The turnover number for Gs alpha- and forskolin-stimulated enzyme activity of the complex between IC1 and IIC2-delta 3 was 8.2 s-1. The concentration of IIC2-delta 3 to achieve half-maximal activation of IC1 was 0.8 and 1.3 microM when stimulated by forskolin and Gs alpha, respectively. The concentration of IIC2-delta 3 needed to complex with IC1 was reduced 10-fold (0.08 microM) when the enzyme was activated by both forskolin and Gs alpha, suggesting that Gs alpha and forskolin increased the affinity of the two cytoplasmic domains for each other.

[Effect of atropine on the enhancing action of Fructus Aurantii Immaturus on the myoelectric activity of small intestine in dogs]

Effect of Fructus Aurantii Immaturus (FAI) was observed by using the computerized electrophysiologic method with the interdigestive myoelectric complex (IDMEC) as criterion. 100% FAI was given to the healthy, awakened and fasting dogs by gastrogavage and as soon as the effect on electric activity of small intestine appeared, atropine was injected. Results showed that the enhancing effect of FAI could be inhibited significantly by atropine, an antagonist of cholinergic receptor. It revealed that although the duration of phase II and general cycle were prolonged, but the spike burst per cluster in the duration between phase II and phase III as well as that per minute were decreased. It suggested the effect of FAI might be relevant with muscarinic receptor.

Myometrial estradiol and progesterone receptor changes in preterm and term pregnancies

OBJECTIVE

To determine if labor is associated with changes in myometrial estradiol (E2) and progesterone receptors.

METHODS

Lower myometrial segments were obtained from women undergoing cesarean deliveries at term in labor (n = 10), term not in labor (n = 10), preterm in labor (n = 9), and preterm not in labor (n = 11). Western immunoblotting was used to determine the presence and molecular size of E2 and progesterone receptor proteins. Immunocytochemistry was used to determine E2 and progesterone receptor changes in preterm and term pregnancies.

RESULTS

Myometrium from pregnant women contained 74-kilodalton (kDa) E2 receptor and 94- and 110-kDa progesterone receptor proteins. These receptors are present in both myometrial smooth muscle and myometrial blood vessels. The nuclei of myometrial smooth muscle cells primarily contain both receptors. The immunostaining for progesterone receptors was less in patients in labor compared with those not in labor in preterm and term pregnancies. In comparing patients not in labor, the immunostaining for progesterone receptors was less at term compared with preterm pregnancy. Unlike the differences in progesterone receptors, there are no obvious differences in E2 receptor immunostaining in myometrial samples from all four groups of women.

CONCLUSION

A myometrial decrease in progesterone receptors, rather than an increase in E2 receptors, may play a role in the onset of labor in women with term or preterm pregnancies.

Immortalized anterior pituitary alpha T3 gonadotropes contain functional luteinizing hormone/human chorionic gonadotropin receptors

Immortalized alpha T3 gonadotropes contain a major 5.0-kb and minor 3.6-, 2.4- and 1.6-kb luteinizing hormone/human chorionic gonadotropin (LH/hCG) receptor transcripts and an 80-kDa receptor protein which can specifically bind 125I-hCG. The relative abundance of the receptors in alpha T3 cells is, however, lower than in gonadal tissues. Culturing alpha T3 cells with highly purified hCG resulted in a dose- and time-dependent and hormone-specific increase in steady-state levels of LH-alpha subunit mRNA. Culturing alpha T3 cells with hCG also resulted in a concomitant increase in the LH-alpha protein levels. As expected, culturing with GnRH also resulted in an increase of LH-alpha subunit mRNA and protein levels. In summary, we conclude that alpha T3 cells contain LH/hCG receptors which are functionally coupled to the up-regulation of LH-alpha subunit gene expression.

Structural analysis of cyclamen seed xyloglucan oligosaccharides using cellulase digestion and spectroscopic methods

Xyloglucan polymers have been isolated from cyclamen seeds and characterized by both liquid and CP-MAS 13C NMR spectroscopy. Treatment of the polysaccharides with cellulase from Trichoderma viride afforded XG oligomers which have been studied with both mass spectrometry and NMR spectroscopy. The repeating unit in the intact polymers and the most abundant hydrolysis product correspond to the Gal1 Xyl3 Glc4 (XXLG) fragment. However, detection of notable amounts of Xyl3 Glc4 (XXXG) and Gal2 Xyl3 Glc4 (XLLG) indicates that the galactose distribution in xyloglucan from cyclamen is irregular. FAB-MS analysis of a new derivative, prepared by forming the glycosamine of m-tetrafluoroethoxy aniline, has led to unambiguous sequence information for the XXLG oligomer.

Oxygenation mechanism of ribulose-bisphosphate carboxylase/oxygenase. Structure and origin of 2-carboxytetritol 1,4-bisphosphate, a novel O2-dependent side product generated by a site-directed mutant

Site-directed mutagenesis has implicated active-site Lys329 of Rhodospirillum rubrum ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) in promoting the reaction of CO2 with the 2,3-enediol of ribulose bisphosphate and in stabilizing carboxylation intermediates [Hartman, F. C., & Lee, E. H. (1989) J. Biol. Chem. 264, 11784-11789; Lorimer, G. H., Chen, Y.-R., & Hartman, F. C. (1993) Biochemistry 32, 9018-9024]. Although the K329A mutant is greatly impaired in carboxylation, it catalyzes formation of the enediol, which is misprocessed to an O2-dependent side product [Harpel, M. R., & Hartman, F. C. (1994) Biochemistry 33, 5553-5561]. We now identify this novel side product as 2-carboxytetritol 1,4-bisphosphate (CTBP) by mass spectrometry, 1H-, 13C-, and 31P-NMR spectroscopy, and periodate oxidation. H2O2 accumulates during formation of CTBP, which we show to be derived from a transient precursor, the dicarbonyl D-glycero-2,3-pentodiulose 1,5-bisphosphate. The isolated dicarbonyl bisphosphate is processed by K329A to CTBP. These results, combined with isotope-labeling studies, suggest that CTBP arises by H2O2 elimination from an improperly stabilized peroxy adduct of the enediol intermediate, followed by rearrangement of the resulting dicarbonyl. Therefore, normal oxygenation, as catalyzed by wild-type Rubisco, is not a spontaneous reaction but must involve stabilization of the peroxy intermediate to mitigate formation of the dicarbonyl bisphosphate and subsequently CTBP. CTBP formation verifies the identity of Rubisco's previously invoked oxygenase intermediate, provides additional mechanistic insight into the oxygenation reaction, and shows that Lys329 promotes oxygenation as well as carboxylation. These results may be relevant to other oxygenases, which also exploit substrate carbanions rather than organic cofactors or transition metals for biological oxygen utilization.

N-acylphosphatidylethanolamine in dry and imbibing cottonseeds. Amounts, molecular species, and enzymatic synthesis

N-Acylphosphatidylethanolamine (NAPE), an unusual acylated derivative of phosphatidylethanolamine (PE), was recently shown to be synthesized from PE and free fatty acids in cotyledons of cotton (Gossypium hirsutum L.) seedlings (K.D. Chapman, T.S. Moore [1993] Plant Physiol 102: 761-769). Here we report that NAPE is present in dry seeds of cotton and increases with time of imbibition from 2.31 nmol/seed in dry seeds to 4.26 nmol/seed in 4-h-soaked seeds. Total phospholipid/seed also increased such that the relative percentage of NAPE was similar in dry and soaked seeds (2.3 mol% compared to 2.6 mol%, respectively). The major molecular species of NAPE were identified in both dry and soaked seeds by fast atom bombardment mass spectrometry and collisionally activated dissociation tandem mass spectrometry as 16:0/18:2-PE(N-palmitoyl), 16:0/18:2-PE(N-linoleoyl), and 18:2/18:2-PE(N-palmitoyl). The specific activity of NAPE synthase in seed extracts increased with increasing time of imbibition from 35 pmol h-1 mg-1 protein in dry seeds to 129 pmol h-1 mg-1 protein in 4-h-soaked seeds. Collectively, our results indicate that NAPE is present in dry cottonseeds and synthesized during imbibition. The biosynthesis of NAPE provides a mechanism for maintaining membrane integrity during seed rehydration and may indicate that NAPE plays a protective role in intracellular membranes of plant tissues, as has been suggested for intracellular membranes of animal tissues.

Fatty acid substrate specificities of human prostaglandin-endoperoxide H synthase-1 and -2. Formation of 12-hydroxy-(9Z, 13E/Z, 15Z)- octadecatrienoic acids from alpha-linolenic acid

Human prostaglandin-endoperoxide H synthase-1 and -2 (hPGHS-1 and hPGHS-2) were expressed by transient transfection of COS-1 cells. Microsomes prepared from the transfected cells were used to measure the rates of oxygenation of several 18- and 20-carbon polyunsaturated fatty acid substrates including eicosapentaenoic, arachidonic, dihomo-gamma-linolenic > alpha-linolenic (delta 9, 12, 15), gamma-linolenic, and linoleic acids. Comparisons of kcat/Km values indicate that the order of efficiency of oxygenation is arachidonate > dihomo-gamma-linolenate > linoleate > alpha-linolenate for both isozymes; while the order of efficiency was the same for hPGHS-1 and hPGHS-2, alpha-linolenate was a particularly poor substrate for hPGHS-1. Gamma-Linolenate and eicosapentaenoate were poor substrates for both isozymes, but in each case, these two fatty acids were better substrates for hPGHS-2 than hPGHS-1. These studies of substrate specificities are consistent with previous studies of the interactions of PGHS isozymes with nonsteroidal anti-inflammatory drugs that have indicated that the cyclooxygenase active site of PGHS-2 is somewhat larger and more accommodating than that of PGHS-1. The major products formed from linoleate and alpha-linolenate were characterized. 13-Hydroxy-(9Z,11E)-octadecadienoic acid was found to be the main product formed from alpha-linoleate by both isozymes. The major products of oxygenation of alpha-linolenate were determined by mass spectrometry to be 12-hydroxy-(9Z,13E/Z,15Z)-octadecatrienoic acids. This result suggests that alpha-linolenate is positioned in the cyclooxygenase active site with a kink in the carbon chain such that hydrogen abstraction occurs from the omega 5-position in contrast to abstraction of the omega 8-hydrogen from other substrates.

Activation of mitogen-activated protein kinase by arachidonic acid in rat liver epithelial WB cells by a protein kinase C-dependent mechanism

Arachidonic acid (20:4(n-6)), which is released by cells responding to a wide range of stimuli, may play an important role in intracellular signaling. We now report that incubation of WB cells with 20:4(n-6) resulted in the appearance of several tyrosine-phosphorylated cytosolic proteins. Two of the phosphotyrosine-containing proteins, migrating in SDS-polyacrylamide gels of approximately 43 and 45 kDa, corresponded in mobility to phosphorylated species of the 42- and 44-kDa mitogen-activated protein kinase (MAPK) isoforms. Immunoblots of soluble fractions from unstimulated WB cells with anti-MAPK antibodies revealed the presence of the 42- and 44-kDa isoforms of MAPK. Upon incubation with 20:4(n-6), the mobility of both isoforms was retarded, consistent with their activation by phosphorylation. Chromatography of soluble fractions from these cells on Mono Q columns revealed early and late eluting peaks of myelin basic protein kinase activity, which contained the 42- and 44-kDa MAPK isoforms, respectively. Activation of MAPK was transient, peaking at 5 min, and was detectable at 5 microM 20:4(n-6). Further studies into the mechanisms by which MAPK was activated by 20:4(n-6) strongly suggested the involvement of protein kinase C (PKC). Not only did incubation of WB cells with 20:4(n-6) result in the translocation of PKC alpha, delta, and epsilon to a particulate fraction, it was found that the fatty acid failed to activate MAPK in cells pretreated for 26 h with phorbol 12-myristate 13-acetate, which depleted WB cells of PKC alpha, delta and epsilon. In addition, fatty acids of the n-3 series were effective activators of MAPK. The present study, to our knowledge, is the first to report that polyunsaturated fatty acids can cause the activation of MAPK.

Accumulation of a novel glycolipid and a betaine lipid in cells of Rhodobacter sphaeroides grown under phosphate limitation

Cells of the photosynthetic bacterium Rhodobacter sphaeroides grown under phosphate-limiting conditions accumulated nonphosphorous glycolipids and lipids carrying head groups derived from amino acids. Concomitantly, the relative amount of phosphoglycerolipids decreased from 90 to 22 mol% of total polar lipids in the membranes. Two lipids, not detectable in cells grown under standard conditions, were synthesized during phosphate-limited growth. Fast atom bombardment mass spectroscopy, exact mass measurements, 1H NMR spectroscopy, sugar composition analysis, and methylation analysis of the predominant glycolipid led to the identification of the novel compound 1,2-di-O-acyl-3-O-[alpha-D-glucopyranosyl-(1-->4)-O-beta-D-galactopyr anosyl]glycerol. The second lipid was identified as the betaine lipid 1,2-di-O-acyl-[4'-(N,N,N-trimethyl)-homoserine]glycerol by cochromatography employing an authentic standard from Chlamydomonas reinhardtii, fast atom bombardment mass spectroscopy, exact mass measurements, and 1H NMR spectroscopy. Prior to this observation, the occurrence of this lipid was thought to be restricted to lower plants and algae. Apparently, these newly synthesized nonphosphorous lipids, in addition to the sulfo- and the ornithine lipid also found in R. sphaeroides grown under optimal conditions, take over the role of phosphoglycerolipids in phosphate-deprived cells.

N-Alkylnicotinium halides: A class of cationic matrix additives for enhancing the sensitivity in negative ion Fast-Atom bombardment mass spectrometry of polyanionic analytes

The addition of some surfactants to the fast-atom bombardment (FAB) matrix previously has been demonstrated to enhance analyte signals in fast-atom bombardment mass spectrometry. In particular, cationic surfactants appear to enhance the negative ion FAB detectability of analytes that exist as anionic species in the matrix solution. It has been proposed that the charged surfactant concentrates the oppositely charged analyte near the surface, which results in larger signals for the analyte. Cationic surfactants that contain a fixed positive charge and an additional basic site were prepared with different hydrophobic moieties and were evaluated for their effectiveness as FAB matrix additives. The compound N-octylnico-tinium bromide (ONBr) is shown to improve greatly the analyte-related signals in negative ion fast-atom bombardment mass spectrometry for a variety of polyanionic analytes, relative to other surfactants (e.g., cetylpyridinium salts). This surfactant not only enhances detectability, but also simplifies the pseudomolecular ion region of the resulting spectra by reducing or eliminating metal cation adduct peaks. The simple mechanism of enhancement via surface activity is evaluated, and alternative mechanisms are considered. It is clearly shown that ONBr, as a FAB matrix additive, will allow mass spectrometry to be used for the analysis of anionic compounds that normally exhibit very low responses.

Isolation of a nitric oxide inhibitor from mammary tumor cells and its characterization as phosphatidyl serine

Macrophages from mice bearing large D1-DMBA-3 mammary tumors have a decreased capacity to kill tumor targets. This effect is due to an impaired ability to produce nitric oxide (NO) in response to lipopolysaccharide (LPS) stimulation. Here we report that the DA-3 tumor cell line, derived from the in vivo adenocarcinoma D1-DMBA-3, produces a factor that inhibits both NO production/release and cytotoxicity of LPS-activated peritoneal exudate macrophages (PEM). However, other complex macrophage functions such as phagocytosis, superoxide production, mitochondrial dehydrogenase activity, and synthesis of proteins were not reduced by this factor. The NO inhibitor has been found to be lipid in nature. Lipid extracts from DA-3 cell culture supernatants were purified by repeated silica gel column chromatography. The active molecule was unambiguously characterized as phosphatidyl serine (PS) by fast atom bombardment tandem mass spectrometry. Preliminary results indicate a lack of induced NO synthase (iNOS) activity in the lysates of LPS-activated PEM pretreated with PS. The ubiquity of PS in the inner leaflet of biological membranes and its NO inhibitory property, suggest that this phospholipid may be one of the long elusive molecules responsible for regulating physiological levels of NO in the host and hence preventing cellular dysfunction and/or tissue damage. Furthermore, the possible overexpression and shedding of PS by DA-3 tumor cells may represent a novel mechanism to impair macrophage cytotoxicity, a host function that contributes to the protection against developing neoplasms.

Insulin-like growth factor binding proteins in serum and follicular fluid from women undergoing ovarian stimulation with and without growth hormone

The effects of supplementary growth hormone (GH) upon insulin-like growth factor binding proteins (IGFBP) in serum and ovarian follicular fluid were investigated in women undergoing buserelin-human menopausal gonadotrophin (HMG) ovulation induction for in-vitro fertilization. IGFBPs were detected by Western ligand blotting (WLB) or radioimmunoassay (IGFBP-3) and were shown in the present study to increase and decrease in patients with diseases of GH excess or deficiency. In the women undergoing treatment for ovulation induction, radioimmunoassay of IGFBP-3 gave results which were consistent with the well-documented GH dependency of this protein, increasing in the serum when GH was administered at the same time as buserelin-HMG. In contrast there were no consistent patterns in the abundance of the IGFBPs in serum and follicular fluid examined by WLB whether or not the patient was receiving GH, and the IGFBPs varied independently of the result obtained by radioimmunoassay. Other studies have shown that during pregnancy a serum protease can dramatically decrease the detection of the IGFBPs on the WLB. However, there was no evidence for a protease in the serum or follicular fluid from these nonpregnant women undergoing ovulation induction. Tissue availability of IGFs is probably regulated by the BPs, so that data would suggest that in normal women, neither ovarian activity nor GH at pharmacological concentrations is the primary regulator of the IGFBPs, which are likely to be regulated by some other factor(s), e.g. nutrition. These data may account for the lack of consistent clinical improvement in studies investigating the hypothesis that supplementary GH during ovulation induction with gonadotrophins would be beneficial.

Insulin-like growth factor-I gene expression in human granulosa-lutein cells

IGF-I is an important local regulator of ovarian function, stimulating follicular growth and steroidogenesis in human granulosa cells. However, it is not known whether ovarian IGF-I is derived from the circulating serum pool or from local production. IGF-I peptide has only been detected in human thecal cells and not in granulosa cells. This study has used the sensitive technique of reverse transcription of mRNA followed by PCR amplification (RT/PCR) to examine IGF-I gene expression in human preovulatory granulosa cells. Granulosa-lutein cell (GLC) samples were obtained by follicular puncture of seven women enrolled in an ovulation induction programme. Treatment had included buserelin acetate, human menopausal gonadotrophin to stimulate follicular growth and human chorionic gonadotrophin to induce ovulation. Total RNA (TRNA), extracted from the GLCs, was amplified by RT/PCR, using combinations of leader and 3' IGF-I exon-specific primers, to yield four IGF-I gene products: IGF-IA (exons 1, 3, 4, 6), IGF-IB (exons 1, 3, 4, 5), IGF-IA' (exons 2, 3, 4, 6) and IGF-IB' (exons 2, 3, 4, 5). As controls from other tissues, an identical procedure was undertaken on TRNA from peripheral blood monocytes and liver. All four mRNAs were expressed in GLCs, monocytes and liver. However the pattern of IGF-I mRNA expression differed between the tissues; in liver and GLCs, the IGF-IA transcript was dominant, but in monocytes the IGF-IA' species was the most prominent. Quantitative RT/PCR using standardization to the house-keeping gene for glyceraldehyde-3'-phosphate dehydrogenase revealed that IGF-IA mRNA was 300-fold more abundant in liver than GLCs.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of amino acids by gas chromatography-flame ionization detection and gas chromatography-mass spectrometry: simultaneous derivatization of functional groups by an aqueous-phase chloroformate-mediated reaction

The one-step ethyl chloroformate derivatization of amino acids in an aqueous medium is extended with the use of a variety of alkyl chloroformate reagents. This provides a new and convenient procedure for preparing esters with different alkoxy groups. A new mechanism for esterification during chloroformate derivatization is proposed based on the formation of an intermediate mixed carboxylic-carbonic acid anhydride followed by the exchange with an alcohol. Among the different reagents investigated, isobutyl chloroformate derivatized amino acids were found to provide more sensitivity for analyses by GC-flame ionization detection and GC-MS relative to derivatives prepared by other alkyl chloroformates.

A double-blind cross-over controlled study to evaluate the effect of human biosynthetic growth hormone on ovarian stimulation in previous poor responders to in-vitro fertilization

The effect of exogenous human biosynthetic growth hormone (HGH; 12 IU/day; Norditropin, Novo-Nordisk) on the response to ovarian stimulation using a buserelin/human menopausal gonadotrophin (HMG) regimen was assessed in women who had previously shown a 'poor response' in spite of increasing doses of HMG. Forty patients were recruited into a prospective double-blind placebo-controlled study. The serum follicle stimulating hormone (FSH) on day 2-5 of a menstrual cycle (< 10 IU/l) was used to exclude any peri-menopausal candidates. The urinary 24 h GH secretion was normal in all patients. Thirty-three patients completed the study with 21 patients having human chorionic gonadotrophin (HCG) in both arms, thus providing a complete set of placebo control data. Of these 21 patients, the administration of HGH compared to the placebo cycle resulted in increased serum concentrations of fasting insulin on the 8th (median 3.9 versus 5.8 mU/l; P < 0.0005) and 13th (median 4.4 versus 5.8 mU/l; P < 0.05) day of HMG in those cycles receiving HGH. After 8 days of co-treatment with HGH the number of cohort follicles (14-16.9 mm) was significantly increased, but this change was not sustained on the day of HCG administration. No statistical difference in the serum oestradiol on the 8th day of HMG or day of HCG, length of the follicular phase, total dose of HMG used, or the number of oocytes collected was seen between the placebo or HGH cycles. This study demonstrates that HGH does not improve the ovarian response to ovulation induction in previous poor responders.

Phospholipid and fatty acid compositions of Rhizobium leguminosarum biovar trifolii ANU843 in relation to flavone-activated pSym nod gene expression

The phospholipid and associated fatty acid compositions of the bacterial symbiont of clover, Rhizobium leguminosarum biovar trifolii wild-type ANU843, was analyzed by two-dimensional silica thin-layer chromatography, fast atom bombardment-mass spectrometry, flame-ionization detection gas-liquid chromatography and combined gas-liquid chromatography/mass spectrometry. The phospholipid composition included phosphatidylethanolamine (15%), N-methylphosphatidylethanolamine (47%), N,N-dimethylphosphatidylethanolamine (9%), phosphatidylglycerol (19%), cardiolipin (5%) and phosphatidylcholine (2%). Fatty acid composition included predominantly cis-11-octadecenoic acid, lower levels of cis-9-hexadecenoic acid, hexadecanoic acid, 11-methyl-11-octadecenoic acid, octadecanoic acid, 11,12-methyleneoctadecanoic acid, eicosanoic acid and traces of branched, and di- and triunsaturated fatty acids. The influence of expression of the "nodulation" genes encoding symbiotic functions on the composition of these membrane lipids was examined in wild-type cells grown with or without the flavone inducer, 4',7-dihydroxyflavone and in mutated cells lacking the entire symbiotic plasmid where these genes reside, or containing single transposon insertions in selected nodulation genes. No significant changes in phospholipid or associated fatty acid compositions were detected by the above methods of analysis.

Supplementary growth hormone treatment of women with poor ovarian response to exogenous gonadotrophins: changes in serum and follicular fluid insulin-like growth factor-1 (IGF-1) and IGF binding protein-3 (IGFBP-3)

The effects of supplementary growth hormone (GH) treatment upon insulin-like growth factor-1 (IGF-1), IGF binding protein-3 (IGFBP-3) concentrations in serum and ovarian follicular fluid were investigated in women undergoing buserelin human menopausal gonadotrophin (HMG) ovulation induction for in-vitro fertilization. Women (n = 40), aged 24-39 (mean 35 years), who showed poor ovarian responses to HMG, were recruited and randomly divided into two groups. Each patient received two cycles of ovulation induction, one with GH (12 IU/day x 12 days/HMG/buserelin) and another with placebo/HMG. Serum IGF-1 increased substantially during the GH treatment and remained significantly higher than the control 2 days after the last GH injection. Serum IGFBP-3 fell steadily during the placebo/HMG treatment and to a nadir on the day of oocyte retrieval (P < 0.05 compared to serum before any treatment). In contrast, IGFBP-3 was increased (P < 0.01) during the GH administration and returned to the control level 2 days after GH injection. Serum oestradiol concentrations on the eighth day of HMG and the day of human chorionic gonadotrophin (HCG) were not significantly different between the two groups. Serum IGF-1 was highly correlated with IGFBP-3 before any treatment (r = 0.433, P < 0.001). This correlation disappeared after buserelin, placebo/HMG treatment in the control group, but it was maintained during GH/HMG treatment (r = 0.343, P = 0.04). Follicular fluid concentrations of GH and IGF-1, not IGFBP-3 or oestradiol, were significantly elevated in the GH-treated women.(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of N-ethoxycarbonyl ethyl esters of amino acids by mass spectrometry

Derivatization of amino acids by using ethyl chloroformate-ethanol-pyridine provides volatile products, N-ethoxycarbonyl amino acid ethyl esters (ECEEs), which are easily amenable to GC or GC-MS analysis. MS behavior of these compounds under electron-impact has been studied. The fragments observed in the spectra facilitate recognition of commonly occurring protein amino acids and characterization of unknown analogues.

Evidence that the putative compatible solute 5-dimethylsulfoniopentanoate is an extraction artifact

A novel gas chromatography-mass spectrometry method for analyzing sulfonium compounds as their S-demethylated silyl derivatives has clarified the origin of 5-dimethylsulfoniopentanoate. This compound, previously reported from flowers of Diplotaxis tenuifolia (L.) DC. (Cruciferae), is generated from glucoerucin during treatment with hot 6 N HCl. Glucoerucin is the characteristic glucosinolate of D. tenuifolia.