Antagonists of phosphatidylinositol 3-kinase block activation of several novel protein kinases in neutrophils

Several novel protein kinases are known to be rapidly activated in neutrophils stimulated with the chemoattractant fMet-Leu-Phe (fMLP). These kinases include a histone H4 protein kinase and several renaturable kinases with molecular masses of about 69, 63, 49, and 40 kDa. The renaturable kinases can catalyze the phosphorylation of a peptide that corresponds to residues 297-331 of the 47-kDa subunit of the NADPH-oxidase system (p47-phox). Previous studies have indicated that the activation of all of these protein kinases involves an uncharacterized stimulatory pathway and/or novel second messenger. The studies reported herein were undertaken to determine if phosphatidylinositol 3-kinase (PI3-K) is a component of this pathway. We report that certain chromosome derivatives (e.g. 2-(4-morpholinyl)-8-phenylchromone (LY294002)) and wortmannin, which inhibit PI3-K by distinct mechanisms, blocked activation of all of these novel kinases. These antagonists also inhibited the phosphorylation of p47-phox (about 50%) and O2.- release (about 80%) in cells stimulated with fMLP, but not with 4 beta-phorbol 12-myristate 13-acetate. A strong correlation exists between the amounts of these antagonists required to produce 50% inhibition of PI3-K in vitro and O2.- release in vivo. In contrast, a single atom substitution of LY294002 produced a compound (LY303511) that did not inhibit PI3-K. Compound LY303511 did not appreciably inhibit the activation of the novel protein kinases or O2.- generation. These data strongly suggest that PI3-K is involved in the activation of several novel protein kinases in neutrophils, one or more of which may be involved in O2.- release.

Synthesis of novel imidazobenzodiazepines as probes of the pharmacophore for "diazepam-insensitive" GABAA receptors

The syntheses of a series of novel imidazobenzodiazepines and their affinities for diazepam sensitive (DS) and diazepam insensitive (DI) GABAA receptors are described. Imidazobenzodiazepines belong to one of the very few chemical families which exhibit high to moderate potency for DI GABAA receptors. Although imidazobenzodiazepines such as Ro 15-4513, 20, are the most potent DI GABAA receptor ligands described to date, their selectivity for DI versus DS GABAA receptors is only marginal. Previous structure-activity relationship (SAR) studies of imidazobenzodiazepines have indicated that the 3- and 8-positions are critical for high-affinity binding to DI GABAA receptors (J. Med. Chem. 1993, 36, 479-490. J. Med. Chem. 1993, 36, 1001-1006. J. Med. Chem. 1993, 36, 1820-1830). In order to determine why the ester function is critical to high affinity at the DI site, we have synthesized several derivatives which have substituents other than an ester at the C(3) position including 3-alkyl-, 3-alkylketo-, 3-alkyl ether, and 3-dialkylamino-substituted imidazobenzodiazepines. The SAR analysis of these compounds when combined with that of several pyrazoloquinolinones indicates that interactions at H1 and L1 as well as interactions at H2 anti to the imidazole N(2) and at a lipophilic pocket (labeled LDi) about the 3-position are required in order for imidazobenzodiazepines to exhibit selectivity and high affinity for DI GABAA receptors. Furthermore, the imidazobenzodiazepines substituted with an electron-donating group (alkoxy function) at position 8 revealed that the change of the substituent at C(8) from an electron-withdrawing to a donating function did not substantially alter either ligand affinity or selectivity for DI GABAA receptors. Thus, a pharmacophore is proposed for DI GABAA receptor ligands, which is characterized by the requirement of a lipophilic pocket LDi about the C(3) position of imidazobenzodiazepines. Using this model, two pyrazoloquinolinone derivatives were designed and synthesized. Their affinities and selectivities for DI GABAA receptors are consistent with those predicted by the DI GABAA receptor pharmacophore. In addition, examination of the in vitro binding data of 3-alkyl ether analogs confirms that the anti conformation of the ester group at the C(3) position of imidazobenzodiazepines (Ro15-4513, 20 series) is preferred at both DI and DS GABAA receptors. This constitutes the first evidence (other than molecular modeling) to support the auxillary involvement of H2 at the DI site and is important with regard to the synthesis of other DI GABAA receptor selective ligands in the future.(ABSTRACT TRUNCATED AT 400 WORDS)

Combined effects of pravastatin and probucol on high-density lipoprotein apolipoprotein A-I kinetics in cholesterol-fed rabbits

The combined effects of pravastatin and probucol on high- density lipoprotein (HDL) apolipoprotein (apo) A-I kinetics in cholesterol (Ch)-fed rabbits were investigated. Japanese White rabbits were treated with 0.15% pravastatin and 0.5% Ch (group 1) or 0.15% pravastatin plus 1% probucol and 0.5% Ch (group 2) for 2 months. After treatment, the serum total cholesterol levels in groups 1 and 2 had significantly (p < 0.01) increased (37.4 +/- 6.7 mg/dl vs 117.1 +/- 46.4 mg/dl, and 31.4 +/- 4.9 mg/dl vs 143.0 +/- 84.5 mg /dl, respectively). The serum HDL-cholesterol levels in both groups decreased (18.2 +/- 2.8 mg/dl, vs 16.2 +/- 3.7 mg/dl p < 0.01 for group 1; 18.2 +/- 1.9 mg/dl vs 15.5 +/- 4.5 mg/dl, ns for group 2). Apo A-I kinetics were assessed by injecting (125)I-labeled HDL intravenously into both groups of rabbits, and taking blood samples periodically for 6 days. Kinetic parameters calculated from apo A-I specific radioactivity decay curves showed that the apo A-I fractional catabolic rates in rabbits fed pravastatin and Ch (group 1) were significantly less than those in rabbits fed pravastatin plus probucol and Ch (group 2) (0.546 +/- 0.017 /day vs 0.730 +/- 0.126 /day, p < 0.05), while the synthetic rate of apo A-I was lower in group 2 than in group 1 (14.76 +/- 1.71 mg/kg per day vs 11.21 +/- 2.38 mg/kg per day, respectively, p < 0.01). These data indicate that pravastatin and probucol have different effects on HDL-apo A-I kinetics in a diet which includes cholesterol.

Determination of manganese in Chinese tea leaves by a catalytic kinetic spectrophotometric method

The catalytic effect of manganese(II) on the oxidation of Rhodamine B with potassium periodate in the presence of 1,10-phenanthroline in acetic acid-sodium acetate was studied. A catalytic kinetic spectrophotometric method for determination of manganese(II) was developed. Manganese in the range 0.1-5.0 ng ml-1 can be determined, and the detection limit is 0.02 ng ml-1. Manganese in Chinese tea leaves was successfully determined.

[Physicochemical properties of a beta-glucan from Sclerotinia sclerotiorum]

Sclerotan (SSG) was an extracellular polysaccharide from Sclerotinia sclerotiorum by submerged fermentation. It had potential immunomodulating and antitumor activity. The SSG was a glucan composed of beta-linked D-glucoses. It was hard to dissolve in water under normal condition, but its aqueous solution had fine rheological properties. Its intrinsic viscosity [eta] hardly changed with ionic strenth. Change of its [eta] value was not remarkable between pH 1.88-12.36. Nevertheless, when the pH came to 13.32, the [eta] value decreased rapidly due to change of molecules conformation. Effect of temperature < or = 90 degrees C and heat treatment on apparent viscosity of SSG solution was minor.

Site and menstrual cycle-dependent expression of proteins of the tumour necrosis factor (TNF) receptor family, and BCL-2 oncoprotein and phase-specific production of TNF alpha in human endometrium

Apoptosis in human endometrial epithelium progressively increases from early to late secretory/menstrual phases and remains consistently more prominent in the basalis. It has been suggested that tumour necrosis factor (TNF) alpha secreted during the secretory/menstrual phases plays a role in induction of programmed cell death in these cells. In the present study, we characterized expression of receptors of TNF alpha, Fas antigen and BCL-2 in endometrial cells to gain insight as to whether this type of cell death in endometrium may be related to differential or preferential expression of these proteins at specific phases of the menstrual cycle. In addition, to relate production of TNF alpha to the development of apoptosis, the amount of TNF alpha released by human endometrium was measured. Immunostaining demonstrated that the TNF receptor (TNFr; p55/60)-I, TNFr-II (p75/80) as well as Fas protein were expressed in endometrial epithelium throughout the entire menstrual cycle. This expression was progressively diminished from the basalis towards the upper functionalis. In the proliferative phase, the expression of BCL-2 was prominent in the endometrial glands particularly in those residing in the basalis. This expression became weak as early as the third post-ovulatory day and remained low during the remaining phases of the menstrual cycle. The amount of TNF alpha released by endometrial fragments obtained from various phases of the menstrual cycle was determined. The amount of TNF alpha released into the culture medium by the endometrium was low in the proliferative phase. However, the amount of released TNF alpha progressively increased in the secretory phase and peaked in the menstrual phase. TNFr-I, TNFr-II, Fas, BCL-2 and TNF alpha could be identified by Western blot analysis of proteins extracted from endometrium. Therefore, endometrial epithelium by virtue of expression of receptors of TNF alpha as well as Fas protein is properly poised to respond to ligand signals that regulate apoptosis. Induction of apoptosis in endometrial epithelium and menstrual shedding may be related to loss of the protective effect of BCL-2 as well as to the amount of TNF alpha.

Simultaneous determination of copper and zinc in the hair of children by pH gradient construction in a flow-injection system

A flow-injection method is described for the simultaneous determination of copper and zinc with a single detector using the pH gradient technique. Zincon is used as the colour reagent for the spectrophotometric determination. The linear range for the determination of zinc is 0.4-12 micrograms ml-1 and for copper is 0.1-3.0 micrograms ml-1. About 20-30 samples can be determined in one hour. The proposed method has been applied to the determination of zinc and copper in childrens' hair.

Protective effect of peptide leukotriene antagonist on renal failure induced by a tourniquet in rabbits

We studied the effects of a selective antagonist of peptide leukotriene D4/E4 (LY-171883) and 5-lipoxygenase inhibitor diethylcarbamazine (DEC) in renal failure induced by a tourniquet, because peptide leukotrienes (LTs) were suggested to play a key role in our previous study. The hind limbs of anesthetized rabbits were fastened for 5 h and then released for 6 h. LY171883 (4 mg/kg/h) and DEC (40 mg/kg/h) were administered via the aural vein from 30 min before the tourniquet and during the experiment in each tourniquet group. The tourniquet induced renal injuries represented by increases in serum BUN and creatinine, and the injuries in the fastened muscles represented increases in serum CPK and edema index of the fastened site. LY171883 and DEC significantly attenuated the aggravation of the renal functions induced by a tourniquet when compared with the vehicle-treated group. LY171883 did not affect the injuries in the fastened muscles, but DEC attenuated it significantly when compared with the vehicle-treated group. The protection of peptide LT antagonist and 5-lipoxygenase inhibitor in the tourniquet-induced renal failure elucidate that peptide LTs trigger renal failure induced by a tourniquet.

Insulin regulates transcription of the CCAAT/enhancer binding protein (C/EBP) alpha, beta, and delta genes in fully-differentiated 3T3-L1 adipocytes

The effect of insulin on expression of CCAAT/enhancer binding protein (C/EBP) alpha, beta, and delta was investigated in fully-differentiated 3T3-L1 adipocytes. Treatment of adipocytes with insulin stimulated rapid dephosphorylation of C/EBP alpha, and repressed the expression of C/EBP alpha within 2-4 h, with > 90% suppression occurring at 24 h. While insulin induced expression of C/EBP beta and C/EBP delta within 1 h and caused a > 20-fold increase by 4 h, expression returned to nearly pretreatment levels by 24 h. The insulin concentration dependence of these effects was consistent with involvement of the insulin receptor. Gel shift analysis revealed that 6 h of insulin treatment decreased the binding of nuclear C/EBP alpha while increasing binding of nuclear C/EBP beta and C/EBP delta. The reciprocal effects of insulin on the steady-state levels of C/EBP transcription factors can be accounted for kinetically and quantitatively by changes in their mRNA levels, which can be accounted for by effects on gene transcription. The effects of insulin on adipocyte gene transcription (e.g. GLUT4) may be mediated, at least in part, by down-regulation of C/EBP alpha and/or its dephosphorylation.

Deletion of lysine 121 creates a temperature-sensitive alteration in insulin binding by the insulin receptor

Recently we reported the deletion of Lys-121 in one allele of the insulin receptor gene from a child with severe insulin resistance. In the present work, this mutant receptor (M121) was shown to have an abnormal sensitivity to temperature and an alteration in "negative cooperativity." In contrast to the wild-type receptor (HIRC), insulin binding by the M121 receptor was rapidly and irreversibly lost at temperatures above 30 degrees C with the phosphorylated form of the receptor being more temperature-sensitive than the nonphosphorylated form. Although insulin binding activity was lost, Western analysis and other studies showed that the mutant receptor remained intact. Measurements of 125I-insulin dissociation at 21 degrees C in the presence of native insulin (an estimate of negative cooperativity) demonstrated a difference between the mutant and wild-type receptor. Insulin dissociation from the mutant receptor was not as pronounced as that found with the wild-type receptor. Thus, an abnormality in insulin binding by the mutation was evident at lower "permissive" temperatures. The results of these and other studies argue that Lys-121 occupies an important position for the regulation of insulin receptor conformation. This regulation apparently influences negative cooperative interactions with insulin and modulates signal transduction.

Association between coronary heart disease and the apolipoprotein A-I/C-III/A-IV complex in a Japanese population

Several studies have reported that a variant allele (S2) of the apolipoprotein (apo) A-I/C-III/A-IV complex is associated with hyperlipoproteinemia in some populations and that the frequency of this allele is two- to fivefold higher in patients with premature coronary heart disease (CHD) than in healthy controls. In the present study in a Japanese population, we were unable to confirm the association of the S2 allele with either coronary heart disease or elevated serum apo C-III levels, as has been previously reported in Caucasians. No genotype difference was observed among the severity of coronary heart disease, as determined by the number of involved vessels (one, two and three vessel disease), compared to controls. In addition, the frequency of the S2 allele among Japanese, in both CHD (0.328) and controls (0.369), was quite different from that in many other populations.

In vitro drug testing of ovarian cancer using the human tumor colony-forming assay: comparison of in vitro response and clinical outcome

The purpose of this study was to assess the prognostic value of in vitro drug chemosensitivity testing using the Hamburger-Salmon human tumor colony-forming assay (HTCA) in fresh tumor samples obtained from newly diagnosed patients with stage II-IV ovarian cancer undergoing maximum cytoreductive surgery and prior to platinum-based chemotherapy. The HTCA was performed on fresh ovarian cancers obtained from 93 patients at their initial exploratory laparotomy to evaluate in vitro sensitivity to cisplatin, carboplatin, and cyclophosphamide following a 1-hr drug exposure. Prospective clinical follow-up was performed on all patients with the primary study endpoints being pathologically proven complete response at second-look surgery and disease-free and overall survival durations. In vitro drug sensitivity was strongly dose-dependent. At a concentration of 5 micrograms/ml only 23% of tumor samples were sensitive (as defined by a > or = 50% decrease in tumor colony-forming units compared to controls) to cisplatin; 13% of tumors were sensitive to carboplatin at a concentration of 50 micrograms/ml and 11% to 4-OH-cyclophosphamide at a concentration of 1 microgram/ml. At doses which were 10 times the previously stated concentrations, the sensitivity rates to cisplatin, carboplatin, and 4-OH-cyclophosphamide increased to 72, 63, and 53%, respectively. Subjects were categorized as having drug-sensitive disease if HTCA results showed in vitro drug sensitivity to at least one of the agents used in their primary chemotherapy. Multivariate analysis failed to show any advantage in clinical response rate, progression-free interval, or survival duration for patients with drug-sensitive disease compared to drug-resistant disease; however, there was evidence of a trend toward an enhanced pathologically proven complete response rate in patients who had chemosensitive tumors in vitro. Second-look surgery was performed in 28 of 55 patients with optimal surgical resections and no clinical evidence of disease at the completion of their primary chemotherapy. Fifty percent (5/10) of patients with drug-sensitive disease achieved a pathologic complete response, while only 3/18 (17%) patients with drug-resistant tumors had a documented pathologic complete response (P = 0.13). As reported in other ovarian cancer studies, patient characteristics which were found to be significantly associated with survival were stage of disease (II-III vs IV), optimal primary surgical resection (i.e., < 1 cm2 residual tumor) vs suboptimal resection, clinical measurability of disease at initiation of chemotherapy, and response to primary chemotherapy. In conclusion, in vitro drug sensitivity, as measured by the HTCA, does not appear to be an independent prognostic factor for survival in patients with stage II-IV epithelial ovarian cancer who undergo standard treatment with tumor debulking surgery and primary platinum-based chemotherapy.(ABSTRACT TRUNCATED AT 400 WORDS)

gamma-Glutamyl transpeptidase is increased by oxidative stress in rat alveolar L2 epithelial cells

The tripeptide glutathione (GSH) is used by cells to detoxify hydroperoxides, produced during oxidative stress, and is consumed in the process. Previous studies have indicated that cells can be protected against oxidative stress by extracellular GSH through its degradation catalyzed by the exoenzyme gamma-glutamyl transpeptidase (gamma GT) and its de novo synthesis within the cytosol. We hypothesized that gamma GT would be increased as part of the adaptation of cells to oxidative stress. We examined whether oxidative stress could increase gamma GT activity, protein, and mRNA in a lung epithelial cell line (L2). Cultures were subjected to H2O2-mediated toxicity by 15 min of exposure to the redox cycling quinone, menadione. Menadione (50 microM) caused an initial decrease (27 +/- 9% of baseline after 15 min) in intracellular GSH, followed by resynthesis to levels significantly higher than baseline (335 +/- 40% after 24 h, P < 0.001). This elevation was prevented by acivicin, a gamma GT inhibitor. Menadione also caused a dose-dependent increase in gamma GT enzymatic activity (715 +/- 125% of control at 24 h after 15 min of exposure to 100 microM menadione, P < 0.001) that was prevented by actinomycin D. Western blot analysis indicated increased levels of gamma GT protein with increasing menadione. A concentration-dependent increase in gamma GT-mRNA was also observed. Previous investigation has demonstrated that an increase in gamma GT activity enhances the capacity of cells to utilize extracellular GSH. The findings presented here are consistent with a role for gamma GT in cellular adaptation to oxidative stress.

Deletion of 3 basepairs resulting in the loss of lysine-121 in the insulin receptor alpha-subunit in a patient with leprechaunism: binding, phosphorylation, and biological activity

We have identified a novel mutation of the human insulin receptor gene in a previously unreported patient with leprechaunism, leprechaun Rochester. This mutation consists of deletion of three nucleotides (GAA) in exon 2 and results in loss of the lysine-121 in the putative ligand-binding domain of the alpha-subunit. To analyze this mutation, we prepared a corresponding mutant insulin receptor by site-directed mutagenesis and expressed the receptor in Chinese hamster ovary cells. Although the mutant receptor displayed normal insulin binding, abnormalities were found in autophosphorylation and in phosphorylation of endogenous and exogenous protein substrates. These abnormalities consisted of increased basal kinase activity, but blunted insulin-stimulated responsiveness. Importantly, cells that expressed the mutant receptor showed markedly decreased insulin- and serum-stimulated DNA synthesis compared to untransfected control cells and cells transfected with the wild-type insulin receptor. These findings suggest that deletion of lysine-121 in conjunction with a presumed, but thus far unidentified, second mutant allele contributed significantly to the lethal insulin-resistant state in this patient with leprechaunism.

Fetal renal vein thrombosis, hydrops fetalis, and maternal lupus anticoagulant. A case report

Hydrops fetalis with fetal renal vein thrombosis in a mother with antiphospholipid antibody syndrome detected post-partum suggests an underlying pathogenetic association that may provide new strategies for treatment of a lethal disorder.