cAMP-mediated inhibition of the epithelial brush border Na+/H+ exchanger, NHE3, requires an associated regulatory protein

NHE3 is the Na+/H+ exchanger located on the intestinal and renal brush border membrane, where it functions in transepithelial Na+ absorption. The brush border Na+ absorptive process is acutely inhibited by activation of cAMP-dependent protein kinase, but the molecular mechanism of this inhibitory effect is poorly understood. We have identified two regulatory proteins, E3KARP and NHERF, that interact with NHE3 to enable cAMP to inhibit NHE3. The two regulatory proteins are structurally related, sharing approximately 50% identity in amino acid sequences. It has been previously shown that when NHE3 is transfected into PS120 fibroblasts or Caco-2 cells, cAMP failed to inhibit NHE3 activity. Northern blot analysis showed that both PS120 and Caco-2 cells lacked the expression of both E3KARP and NHERF. In contrast, other cell lines in which cAMP inhibits NHE3, including OK, CHO, and LLC-PK1 cells, expressed NHERF-related regulatory proteins. To determine their functions in cAMP-dependent inhibition of NHE3, E3KARP and NHERF were transfected into PS120/NHE3 fibroblasts. Transfection in PS120/NHE3 fibroblasts with either NHERF or E3KARP reconstituted cAMP-induced inhibition of NHE3, resulting in 25-30% inhibition in these cells.

Blockade by naloxone of cocaine-induced hyperactivity, reverse tolerance and conditioned place preference in mice

Cocaine-induced hyperactivity was inhibited by a single administration of naloxone (2 and 5 mg/kg, i.p.), an opioid receptor antagonist, and naloxone administered prior to and during the chronic injection of cocaine attenuated the development of both cocaine-induced reverse tolerance and conditioned place preference (CPP). Dopamine (DA) receptor supersensitivity which developed in cocaine-induced reverse tolerant or CPP mice, was also inhibited by naloxone. Furthermore, naloxone reduced an apomorphine-induced striatal dopaminergic action, climbing behavior. Therefore, the present studies suggest that cocaine-induced dopaminergic behaviors, such as hyperactivity, reverse tolerance and CPP, may be commonly produced via activation of an opioid receptor. The development of DA receptor supersensitivity may be a possible common mechanism of cocaine-induced reverse tolerance and CPP, since cocaine-induced changes in sensitivity to apomorphine, as well as apomorphine-induced climbing behavior in mice, were both inhibited by naloxone.

Effects of L-trans-pyrrolidine-2,4-dicarboxylate, a glutamate uptake inhibitor, on NMDA receptor-mediated calcium influx and extracellular glutamate accumulation in cultured cerebellar granule neurons

Glutamate uptake inhibitor, L-trans-pyrrolidine-2,4-dicarboxylate (PDC, 20 muM) elevated basal and N-methyl-D-aspartate (NMDA, 100 muM)-induced extracellular glutamate accumulation, while it did not augment kainate (100 muM)-induced glutamate accumulation in cultured cerebellar granule neurons. However, pretreatment with PDC for 1 h significantly reduced NMDA-induced glutamate accumulation, but did not affect kainate-induced response. Pretreatment with glutamate (5 muM) for 1 h also reduced NMDA-induced glutamate accumulation, but did not kainate-induced response. Upon a brief application (3-10 min), PDC did neither induce elevation of intracellular calcium concentration ([Ca(2+)](i)) nor modulate NMDA-induced [Ca(2+)](i) elevation. Pretreatment with PDC for 1 h reduced NMDA-induced [Ca(2+)](i) elevation, but it did not reduce kainate-induced [Ca(2+)](i) elevation. These results suggest that glutamate concentration in synaptic clefts of neuronal cells is increased by prolonged exposure (1 h) of the cells to PDC, and the accumulated glutamate subsequently induces selective desensitization of NMDA receptor.

Dual effects of NMDA-induced intracellular Ca2+ elevations on cGMP levels in cultured cerebellar granule neurons

1. Cyclic GMP (cGMP) levels were markedly elevated by N-methyl-D-aspartate (NMDA) within 1-3 min of incubation, then gradually decreased with incubation time. 2. The NMDA-induced intracellular Ca2+ elevations showed maximal levels just after adding NMDA and were maintained for 60 min. 3. NMDA did not show augmentation of cGMP elevation with sodium nitroprusside (SNP), rather it decreased the SNP-induced cGMP elevation after exposure for 60 min. 4. The NMDA-induced elevation of cGMP was remarkably augmented with the phosphodiesterase inhibitor, 3-isobutyl-1-methylxanthine (IBMX, 1mM), after 60 min of incubation.

AutoPap system performance in screening for low prevalence and small cell abnormalities

OBJECTIVE

To summarize the design principles of the AutoPap System evaluation score by evaluating slides having a low prevalence of abnormal cells and small cell abnormalities and assessing the evaluation score as a diagnostic tool.

STUDY DESIGN

Data from two clinical studies conducted using the AutoPap System and data obtained from the evaluation score training slides were analyzed to demonstrate the effectiveness of the evaluation score. The clinical studies included a prospective, intended-use study involving approximately 13,000 slides and a comprehensive sensitivity study using approximately 1,200 slides from five laboratories. The evaluation score training set consisted of 4,174 slides from 10 laboratories.

RESULTS

The robust design of the AutoPap evaluation score was demonstrated by similar detection capabilities and sensitivities to slides having either a low or high prevalence of abnormal cells. No significant difference in performance was detected between the small cell slides and the comparison groups of carcinoma in situ and invasive squamous carcinoma having normal-sized abnormal cells. In addition, the evaluation scores corresponded well to the diagnostic severity of the slides.

Antisense oligonucleotides demonstrate a dominant role of c-Ki-RAS proteins in regulating the proliferation of diploid human fibroblasts

Although members of the RAS protein family (Ha-, Ki-, and N-RAS) are known to play a key role in normal cell proliferation and to be frequently mutated in naturally occurring tumors, it remains unclear which of these proteins functions to regulate growth in normal cells. Gene-specific oligonucleotides (oligos) against c-Ki-RAS (ISIS 6957), c-Ha-RAS (ISIS 2503), and oncogenic Ha-RAS (ISIS 2570) were used to analyze the requirement for individual RAS proteins in the proliferation of diploid human lung fibroblasts (MRC-5), and human bladder carcinoma cell lines with (T24) or without (J-82) a RAS mutation. The oncogenic Ha-RAS oligo substantially inhibited T24 cell proliferation, whereas the c-Ki-RAS and control (ISIS 1966) oligos had little effect. Interestingly, in MRC-5 cells the c-Ki-RAS but not c-Ha-RAS oligo was effective in inhibiting cell proliferation. No inhibition was seen in the J-82 cells with either oligo. In Western analysis, p21 RAS protein was decreased following treatment with the oncogenic Ha-RAS oligo in T24 cells or the c-Ki-RAS oligo in MRC-5 cells, whereas no reductions were observed in J-82 cells with either oligo. The specificity of these oligos was demonstrated in Northern analyses in which both Ha-RAS and Ki-RAS oligo treatment resulted in reduced levels of their respective mRNAs in all three cell lines, whereas the mutant Ha-RAS mRNA in T24 cells was most effectively reduced with the oncogenic Ha-RAS oligo. These results demonstrate that oncogenic Ha-RAS plays an important role in the proliferation of T24 cells, whereas c-Ki-RAS contributes predominantly to the proliferation of normal MRC-5 cells.

Blockade by ginseng total saponin of methamphetamine-induced hyperactivity and conditioned place preference in mice

Ginseng total saponin (GTS) inhibited methamphetamine-induced hyperactivity and conditioned place preference (CPP). Dopamine (DA) receptor supersensitivity was developed in methamphetamine-induced CPP mice and it was inhibited by GTS. GTS also inhibited apomorphine-induced climbing behavior, showing the antidopaminergic activity of GTS. These results suggest that GTS inhibition of the methamphetamine-induced hyperactivity and CPP may be closely related with the inhibition of dopaminergic activation induced by methamphetamine.

Infiltration of neutrophils by intrapleural injection of tumour necrosis factor, interleukin-1, and interleukin-8 in rats, and its modification by actinomycin D

1. To assess in vivo chemotactic activity of tumour necrosis factor (TNF), interleukin-1 (IL-1), IL-8, and cytokine-induced neutrophil chemoattractant (CINC), we injected these cytokines into the pleural cavity of rats. 2. CINC (0.1-1 microgram) and recombinant human IL-8 (rhIL-8, 0.2-5 micrograms) caused neutrophil infiltration into the rat pleural cavity in a dose-dependent fashion, peaking at 3 h. The number of leukocytes in the peripheral blood did not change significantly. 3. RhTNF alpha and rhIL-1 alpha also induced neutrophil accumulation. The dose response curves of rhTNF alpha (0.67 ng-6.7 micrograms) and rhIL-1 alpha (0.45 ng-4.5 micrograms) at 3 h were bell shaped. On the other hand, unlike CINC and rhIL-8, rhTNF alpha and rhIL-1 alpha caused transient marked leukopenia at 3 h in a simple dose-dependent fashion. 4. Concomitant injection of actinomycin D dose-dependently and completely at 10 micrograms inhibited neutrophil infiltration induced by rhTNF alpha (0.67 microgram) and rhIL-1 alpha (0.45 microgram) at 3 h. However, that induced by CINC or rhIL-8 was not affected by actinomycin D. 5. Peaking at 1 h, CINC production in the pleural cavity was found after intrapleural injection of rhTNF alpha (0.67 microgram) or rhIL-1 alpha (0.45 microgram), but not after that of rhIL-8 (5 micrograms). The CINC production induced by rhTNF alpha or rhIL-1 alpha and the neutrophil infiltration was suppressed by concomitant injection of actinomycin D (1 and 10 micrograms). 6. These results indicate that CINC and IL-8 themselves are direct chemoattractants for neutrophils, whereas TNF and IL-1 induce neutrophil infiltration indirectly via newly synthesized mRNA for chemotactic protein including CINC, which may be involved in neutrophil emigration at local inflammatory sites in rats.

Kainate produces concentration-dependent elevation of glutamate release but not cGMP levels in cultured neuron

1. Treatment of cultured cerebellar granule cells for 3 min with N-methyl-D-aspartate (NMDA) resulted in a concentration-dependent elevation of cyclic GMP. However, neither kainate (KA) nor NMDA produced a concentration-dependent elevation of this nucleotide after exposing cells to the agonist for 60 min. 2. Unlike the case for cGMP, both KA and NMDA produced concentration-dependent elevations of glutamate for 60 min incubation. 3. The NMDA-induced elevations of cGMP and glutamate were blocked by selective NMDA receptor antagonists. 4. The selective KA/alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA) receptor antagonist, 6,7-nitroquinoxaline-2,3-dione (DNQX), blocked the KA-induced elevations of cGMP with 3-min exposures, but it augmented the response with 60-min exposures. However, the KA-induced release of glutamate was prevented by DNQX. 5. The KA/AMPA receptor antagonist, GYKI 52466, blocked all KA-induced responses regardless of the incubation times.

Inhibition by MK-801 of cocaine-induced sensitization, conditioned place preference, and dopamine-receptor supersensitivity in mice

Repeated administration of cocaine led to increases in ambulation-accelerating activity (sensitization) and conditioned place preference (CPP). Dopamine (DA)-receptor supersensitivity was also developed in cocaine-induced sensitized and CPP mice. An N-methyl-D-aspartate (NMDA)-receptor antagonist, MK-801, blocked simultaneously developments of cocaine-induced behavioral sensitization, CPP, and DA-receptor supersensitivity. Furthermore, MK-801 inhibited a apomorphine-induced striatal dopaminergic action: climbing behavior. These results suggest that the cocaine-induced dopaminergic behaviors such as sensitization to ambulatory activity and CPP may be produced via activation of the NMDA receptor. The development of postsynaptic DA-receptor supersensitivity may be an underlying common mechanism that mediates cocaine-induced behavioral sensitization and CPP.

Optimizing conditions for the growth of Lactobacillus casei YIT 9018 in tryptone-yeast extract-glucose medium by using response surface methodology

This study was undertaken to find optimum conditions of tryptone, yeast extract, glucose, Tween 80, and incubation temperature for the growth of Lactobacillus casei YIT 9018 and to assess the effects of these factors by use of response surface methodology. A central composite design was used as an experimental design for allocation of treatment combinations. A second-order polynomial regression model, which was used at first for analysis of the experiment, had a significant lack of fit. Therefore, cubic and quartic terms were incorporated into the regression model through variable selection procedures. Effects involving incubation temperature, yeast extract, glucose, and tryptone were significant, whereas the only significant effect involving Tween 80 was the interaction effect between temperature and Tween 80. It turned out that growth of L. casei YIT 9018 was most strongly affected by the incubation temperature. Estimated optimum conditions of the factors for growth of L. casei YIT 9018 are as follows: tryptone, 3.04%; yeast extract, 0.892%; glucose, 1.58%; Tween 80, 0%; incubation temperature, 35 degrees C.

Nonionic contrast agents produce thrombotic effect by inducing adhesion of leukocytes on human endothelium

The expression of P-selectin was more upregulated following the exposure to nonionic low osmolar contrast agents than to ionic contrast agents. Exposure to nonionic contrast agents led to a marked adhesion of leukocytes to endothelial cells. Thrombomodulin activity of endothelial cells was decreased, and plasminogen activator inhibitor-1 (PAI-1) and tumor necrosis factor (TNF) alpha in the supernatant were increased when leukocyte adhesion occurred after exposure to nonionic contrast agents. Results suggest that the adhesion of leukocytes to the endothelium increases procoagulant activity.

The iron component of sodium nitroprusside blocks NMDA-induced glutamate accumulation and intracellular Ca2+ elevation

These studies were designed to compare the effects of nitric oxide (NO) generating compounds with those of several iron containing compounds which do not generate NO on glutamate receptor function. Stimulation of primary cultures of cerebellar granule cells with N-methyl-D-aspartate (NMDA) or kainate results in the elevation of intracellular calcium ([Ca2+]i) and cGMP and the release of glutamate. The iron containing compounds, sodium nitroprusside (SNP), potassium ferrocyanide (K4Fe(CN)6) and potassium ferricyanide (K3Fe(CN)6) decrease the NMDA-induced release of glutamate. SNP is the only compound of the above 3 agents which generates NO. A non-iron, NO generating compound, S-nitroso-N-acetylpenicillamin (SNAP), has no effect on the NMDA-induced glutamate release. Potassium ferrocyanide (Fe II), but not potassium ferricyanide (Fe III), blocks NMDA-induced cGMP elevations after 3 min exposure times. This contrasts with the NO generating compounds (both SNP and SNAP) which elevate cGMP levels. Furthermore, both potassium ferrocyanide (Fe II) and SNP (Fe II) suppress the elevation of [Ca2+]i induced by NMDA but neither potassium ferricyanide (Fe III) nor SNAP are effective in this regard. These effects are also independent of cyanide as another Fe II compound, ferrous sulfate (FeSO4) is also able to suppress NMDA-induced elevations of [Ca2+]i. SNP was unable to suppress kainate receptor functions. Collectively, these results indicate that Fe II, independently of NO, has effects on NMDA receptor function.

The generation of nitric oxide and its roles in neurotransmission and neurotoxicity

The N-methyl-D-aspartate (NMDA) receptor plays a key role in synaptic plasticity and is thought to underlie memory, learning and development of the nervous system. The NMDA receptor is a ligand-gated ion channel complex that contains distinct recognition sites for endogenous and exogenous ligands, including glutamate, glycine, Mg2+, Zn2+ and noncompetitive blockers such as MK-801. In the central nervous system, nitric oxide (NO) is produced in some neurons following activation of excitatory amino acids receptors, particularly those of the NMDA receptor. Nitric oxide is synthesized from a L-arginine by the cytoplasmic enzyme nitric oxide synthase (NOS) which is a calcium dependent enzyme, and this pathway is inhibited by the analogues of L-arginine such as NG-monomethyl-L-arginine (L-NMMA) and is augmented by NMDA receptor activation. Activation of the NMDA receptor results in the elevation of intracellular calcium ([Ca2+]i) which in turn activates NOS via the calcium-calmodulin complex. Nitric oxide is not a classical neurotransmitter in the central nervous system since it is not released by exocytosis and does not interact with a receptor protein but rather diffuses rapidly across the membrane and binds with the iron in heme-containing proteins. Nitric oxide can serve as both an oxidizing and reducing agent. It has strong affinity for heme proteins such as guanylyl cyclase, but there is evident that NO may have a regulatory role by oxidizing sulfhydryl groups of non-heme proteins such as those on the NMDA receptor.(ABSTRACT TRUNCATED AT 250 WORDS)

Deposition of transforming growth factor-beta in the marrow in myelofibrosis, and the intracellular localization and secretion of TGF-beta by leukemic cells

The marrows of 10 patients with hematologic malignancies were examined by immunohistochemistry using anti TGF-beta antibody, CC(1-30), which detects secreted TGF-beta, and compared with four normal marrows. TGF-beta was not demonstrated in marrows with a normal level of reticulin fibrosis; however, TGF-beta was observed within collagen in marrows having collagen fibrosis or increased reticulin fibrosis. The extent of TGF-beta deposition paralleled the severity of fibrosis (P < .0001), and occurred even with normal or reduced numbers of megakaryocytes. Using another TGF-beta antibody, LC(1-30), which detects intracellular TGF-beta, TGF-beta was detected by immunofluorescence in discrete sites in the cytoplasm of immature and mature myeloid and large granular lymphocytic leukemia cells. These sites colocalized with areas detected by an anti-granule antibody (D545) suggesting that TGF-beta was stored in granules. However, neither the TGF-beta mRNA content nor the degree of TGF-beta secretion by these leukemic cells correlated with the extent of TGF-beta deposition in the marrow. Thus, TGF-beta deposition in marrow may contribute to myelofibrosis, but the source of this cytokine in the absence of megakaryocytes requires further study.