Down-regulation of NF-kappaB activity and NF-kappaB p65 subunit expression by ras and polyoma middle T oncogenes in human colonic Caco-2 cells

The products of ras and src proto-oncogenes are frequently activated in a constitutive state in human colorectal cancer. In this study we attempted to establish whether the tumorigenic progression induced by oncogenic activation of p21ras or pp60c-src in human colonic cells is associated with alterations of the activity and expression of nuclear factor kappaB (NF-kappaB), a transcription factor suspected to participate in the development of cancer. To this end, we used Caco-2 cells made highly tumorigenic by transfection with an activated Val-12 human Ha-ras gene or with the polyoma middle T (PyMT) oncogene, a constitutive activator of pp60c-src tyrosine kinase activity. Compared with control vector-transfected Caco-2 cells, both oncogene-transfected cell lines exhibited: (i) decreased constitutive NF-kappaB DNA-binding activity and NF-kappaB-mediated reporter gene expression, without alteration of their response to TNF-alpha for activation of these parameters; (ii) reduced NF-kappaB cytosolic stores along with a decreased p65 expression due, at least in part, to destabilization of p65 mRNA; (iii) a decrease in adhesion to extracellular matrix component-coated substrata which was partially corrected when stimulating NF-kappaB transcriptional activity with TNF-alpha. These results indicate that the tumorigenic progression induced by oncogenic p21ras or PyMT/pp60c-src in human colonic Caco-2 cells is associated with a down-regulation of p65 expression and NF-kappaB activity which could be responsible for the reduced adhesive properties of these cells after oncogene transfection.

Skin sensitization to eugenol and isoeugenol in mice: possible metabolic pathways involving ortho-quinone and quinone methide intermediates

With the aim of providing further mechanistic insights into the mode of action of eugenol (4-allyl-2-methoxyphenol) and isoeugenol (4-propenyl-2-methoxyphenol), we have synthesized two series of modified compounds which were tested in the mouse local lymph node assay for their skin sensitizing potential. The replacement of the methoxy group by an isopropoxy group led to a complete loss of sensitization for the eugenol derivative 6a, while no significant effect was observed for the isoeugenol derivative 6b. In the eugenol series, when methyl groups were present in the 3-, 5-, or 6-position a significant reduction in sensitization potential was observed while in the isoeugenol series only methyl substitution in the 3- and 5-position had a discernable effect. Introduction of three methyl groups on the aromatic ring of eugenol (3,5,6-trimethyl-4-allyl-2-methoxyphenol, 7) and of a tert-butyl substituent at the gamma-position of the alkyl chain of isoeugenol (4-[3',3',3'-trimethylpropenyl]-2-methoxyphenol, 8) led to a strong decrease of the sensitizing capacity. Our findings indicate that, at least in the mouse, eugenol could sensitize via a demethylation pathway followed by oxidation to the o-quinone which could act directly as a hapten even if we cannot exclude a reaction via its tautomeric p-quinone methide. Isoeugenol, on the other hand, could act via a mechanism not involving demethylation and for which the evidence is consistent with a direct oxidation to the p-quinone methide.

Specific IgE detected by ELISA and immunoblot after human cytomegalovirus infection (HCMV) in renal transplant (RT) recipients

BACKGROUND

Specific HCMV IgE response has been reported by some authors, and was proposed as a valuable virologic marker of CMV infection.

OBJECTIVES

we evaluated specific HCMV IgE in renal transplant patients with active (primary and secondary) HCMV infection with special interest to symptomatic infections.

STUDY DESIGN

Specific IgE was tested retrospectively by ELISA and immunoblot (IB) on sera of 55 RT patients who were followed before and after transplantation with virologic markers of CMV infection.

RESULTS

Total serum IgE levels were similar in control group and in patients with primary and secondary HCMV infections. Anti-CMV specific IgE response by ELISA was more frequently found in patients with primary infection (76.9%) than in patients with secondary infection (47.1%). These specific IgE reacted on immunoblot with a 150 kDa protein in 84.6% of patients with primary infection and 94.1% with secondary infections; and reacted with rp52 (pUL44) in 76.9% of primary infection and 47.1% of secondary infection.

CONCLUSIONS

Anti-CMV specific IgE tested by immunoblot and ELISA is a marker of CMV infection. It was clearly detected in cases of active infection (primary and secondary) and was present in cases with severe CMV clinical manifestations. In contrast, anti-CMV specific IgE, was consistently negative among healthy blood donors. This is the first report of CMV proteins detected by IgE immunoblot.

Ultraviolet-A induces activation of AP-1 in cultured human keratinocytes

UV-A irradiation induces a time-dependent activation of AP-1 in NCTC 2544 human keratinocytes. 4 h after irradiation, a 2-3-fold increase in AP-1 activity is observed in human keratinocytes and fibroblasts. Activation is still detectable 24 h later. The UV-A induced AP-1 binding complex is shown to contain c-Fos and c-Jun proteins. Lipophilic vitamin E impedes UV-A induced lipid peroxidation but does not prevent AP-1 activation which is inhibited by N-acetylcysteine, a hydrophilic antioxidant. This finding suggests that UV-A-dependent AP-1 activation is sensitive to the cellular redox state but is not related to membrane lipid peroxidation.

Myocellular enzyme leakage, polymorphonuclear neutrophil activation and delayed onset muscle soreness induced by isokinetic eccentric exercise

To address the question of whether delayed onset muscular soreness (DOMS) following intense eccentric muscle contraction could be due to increased production of the arachidonic acid derived product prostaglandin E2 (PGE2). 10 healthy male subjects were submitted to eccentric and concentric isokinetic exercises on a Kin Trex device at 60 degrees/s angular velocity. Exercise consisted of 8 stages of 5 maximal contractions of the knee extensor and flexor muscle groups of both legs separated by 1 min rest phases. There was an interval of at least 30 days between eccentric and concentric testing, and the order of the two exercise sessions was randomly assigned. The subjective presence and intensity of DOMS was evaluated using a visual analogue scale, immediately, following 24 h and 48 h after each test. Five blood samples were drawn from an antecubital vein: at rest before exercise, immediately after, after 30 min recovery, 24 h and 48 h after the tests. The magnitude of the acute inflammatory response to exercise was assessed by measuring plasma levels of polymorphonuclear elastase ([EL]), myeloperoxidase ([MPO]) and PGE2 ([PGE2]). Using two way analysis of variance, it appeared that only eccentric exercise significantly increased [EL] and DOMS, especially of the hamstring muscles. Furthermore, a significant decrease in eccentric peak torque of this muscle group only was observed on day 2 after eccentric work (- 21%; P < 0.002). Serum activity of creatine kinase and serum concentration of myoglobin increased significantly 24 and 48 h after both exercise tests. However, these variables reached significantly higher values following eccentric contractions 48 h after exercise. Mean [PGE2] in the two exercise modes remained unchanged over time and were practically equal at each time point. On the basis of these findings, we conclude that the magnitude of polymorphonuclear (PMN) activation, muscle damage, and DOMS are greater after eccentric than after concentric muscle contractions. However, the hypothesized interplay between muscle damage, increased PGE2 production, DOMS sensations, and reduced isokinetic muscle performance was not substantiated by the present results.

Insulin activates nuclear factor kappa B in mammalian cells through a Raf-1-mediated pathway

We examined the effect of insulin on nuclear factor kappa B (NF-kappa B) activity in Chinese ovary (CHO) cells overexpressing wild-type (CHO-R cells) or -defective insulin receptors mutated at Tyr1162 and Tyr1163 autophosphorylation sites (CHO-Y2 cells). In CHO-R cells, insulin caused a specific, time-, and concentration-dependent activation of NF-kappa B. The insulin-induced DNA-binding complex was identified as the p50/p65 heterodimer. Insulin activation of NF-kappa B: 1) was related to insulin receptor number and tyrosine kinase activity since it was markedly reduced in parental CHO cells which proved to respond to insulin growth factor-1 and phorbol 12-myristate 13-acetate (PMA) activation, and was dramatically decreased in CHO-Y2 cells; 2) persisted in the presence of cycloheximide and was blocked by pyrrolidine dithiocarbamate, aspirin and sodium salicylate, three compounds interfering with I kappa B degradation and/or NF-kappa B.I kappa B complex dissociation; 3) was independent of both PMA-sensitive and atypical (zeta) protein kinases C; and 4) was dependent on Raf-1 kinase activity since insulin-stimulated NF-kappa B DNA binding activity was inhibited by 8-bromo-cAMP, a Raf-1 kinase inhibitor. Moreover, insulin activation of NF-kappa B-driven luciferase reporter gene expression was blocked in CHO-R cells expressing a Raf-1 dominant negative mutant. This is the first evidence that insulin activates NF-kappa B in mammalian cells through a post-translational mechanism requiring both insulin receptor tyrosine kinase and Raf-1 kinase activities.

[Oncogenic activation of p21(ras) and pp60(c-src) in human colonic Caco-2 cells decreases insulin receptor function and expression through protein kinase C-dependent and independent pathways]

In view of the potent mitogenic effect exerted by insulin in human colonic cells, we used Caco-2 cells transfected with an activated (Val12) human Ha-ras gene or the polyoma middle T (PyMT) oncogene, a constitutive activator of pp60c-src tyrosine kinase activity, to investigate the effect of oncogenic p21ras and PyMT/pp60c-src on insulin mitogenic signaling. As compared to vector control Caco-2 cells, both oncogene-transfected cells exhibited: 1) a lost of response to insulin's stimulatory effect on mitogen-activated protein (MAP) kinase activity and cell proliferation, both of which were constitutively increased; 2) a decrease in insulin receptor (IR) affinity and insulin-stimulated exogenous tyrosine kinase activity, which resulted, at least in part, from increased protein kinase C (PKC) activity (4), since both IR alterations were partially corrected by PKC down-regulation; and 3) a decrease in both insulin receptor mRNA level and insulin receptor number, which was independent of PKC since it persisted after PKC down-regulation. In conclusion, oncogenic p21ras and PyMT/pp60c-src abolished insulin mitogenic signaling in Caco-2 cells through mechanisms involving (i) constitutive activation of MAP kinase, and (ii) marked decreases in both insulin receptor function and expression which were mediated by PKC-dependent and PKC-independent pathways respectively. This is the first evidence that, when oncogenically activated, p21ras and pp60c-src not only exert a negative control on insulin receptor function but also repress insulin receptor gene expression in human colonic cells.

Grading of cystosarcoma phyllodes by texture analysis of tissue architecture

Conventional histologic grading of cystosarcoma phyllodes of the breast has not been entirely successful in the prognosis of recurrence or metastasis. Our study first developed a tumor grade classification based on computerized texture features and then compared the classification to conventional grading of these tumors. Evaluation of the tissue architecture of histologic sections was obtained by measuring nine texture features on an image analysis system. Forty cases of cystosarcoma phyllodes were studied. Each parameter was calculated on subimages of 128 x 128 pixels. This size resulted from a preliminary study that confirmed that the difference between texture primitives depends on the area of subimages. We also compared our series to a panel of 20 extramammary sarcomas. The results show that tissue architecture evaluated by texture analysis allows good discrimination between benign, borderline and malignant cystosarcoma phyllodes. Furthermore, extramammary sarcomas and malignant cystosarcoma phyllodes were discriminated well in most cases.

Phosphorylation of vimentin is an intermediate step in protein kinase C-mediated glycoconjugate secretion

We have previously shown that fibroblasts from patients with cystic fibrosis (CF) display a higher response to 4 beta-phorbol 12-myristate 13-acetate (PMA) than control fibroblasts for stimulation of both protein kinase C (PKC) cytosol-to-membrane translocation and glycoconjugate secretion. In this study we took advantage of these cells with differential responsiveness to PMA to investigate the endogenous substrate(s) involved in PKC stimulation of glycoconjugate secretion after verification of cystic fibrosis transmembrane conductance regulator gene expression in control and CF fibroblasts. We show that a 57-kDa protein that was associated with cytoskeleton and was identified as vimentin by immunoblotting emerged as a good candidate for mediating PKC stimulation of glycoconjugate secretion. 1) Its phosphorylation by PMA was abolished by PKC inhibition or depletion. 2) In both control and CF fibroblasts, the PMA-induced increase in its phosphorylation preceded the phorbol ester stimulation of glycoconjugate secretion. 3) For both processes, the concentration-response curves were superimposable, with higher maximal levels for CF fibroblasts relative to controls. 4) PMA-stimulated 57-kDa protein phosphorylation, like PMA-stimulated glycoconjugate secretion, was significantly increased by Ca2+. 5) Increased PMA phosphorylation of the 57-kDa protein as a result of okadaic acid inhibition of intracellular phosphatases was reflected in increased PMA stimulation of glycoconjugate secretion. In conclusion, 1) PMA phosphorylation of a cytoskeletal 57-kDa protein, identified as vimentin, appears to be an intermediate step in PKC stimulation of constitutive glycoconjugate secretion in human skin fibroblasts; and 2) this process is impaired in CF disease.

Intoxication from Veratrum album

Two new cases of Veratrum poisoning are described. Clinical symptoms occurred quickly, within 30 min. Vomiting, a fall in blood pressure and bradycardia were observed. The outcome was favourable in both cases, producing a cure without sequellae. Examination of the literature showed that such cases are nearly always accidental, resulting from the difficulty in distinguishing Veratrum album and Gentiana.

Selective intra-lysosomal concentration of niobium in kidney and bone marrow cells: a microanalytical study

Niobium is used as an alloy in the industrial and biomedical fields. The concentration of the toxic element in organs of a number of animal species has been defined by using radioactive niobium (95Nb). However, tissue lesions induced by niobium have only been studied at the light microscopy level. In this study, we used an electron probe X-ray analyzer equipped with a transmission electron microscope to define the localization of this element in kidney and bone marrow cells. Results demonstrated that niobium is located in the lysosome and that this element coprecipitates with phosphate. In kidney, lysosomes and precipitates are eliminated in the tubular lumen. In contrast, precipitates appear to be eliminated more slowly from the lysosomes of bone marrow macrophages. These processes therefore correspond to one of the mechanisms by which lysosomes eliminate certain toxic mineral elements and thus play a role in the more general process of the body's defenses.

Assessment of the clinical value of urinary trypsin inhibitory activity in elderly people

To assess the clinical value of urinary trypsin inhibitory activity (UTIA) in elderly people, a prospective study was carried out over 4 months in our internal medicine department. Two hundred and forty-three patients of more than 60 years of age were included. A positive correlation was observed between UTIA and serum creatinine (p < 10(-3)). In the population with serum creatinine of less than 133 mumol/l (200 patients), UTIA was independent of age, sex and serum creatinine. UTIA was compared with seven serum inflammatory proteins titrated on patient admission. The principal interest of UTIA determination appeared in bacterial infections. UTIA was significantly increased in this group (p < 10(-4)). However, a positive correlation was proved only with C-reactive protein (CRP) (p = 9 x 10(-4)). Nevertheless, CRP appeared to be the best marker of bacterial infectious diseases after receiver operating characteristic curves analysis.

Extrahepatic metabolism of propofol in man during the anhepatic phase of orthotopic liver transplantation

We have investigated extrahepatic metabolism of propofol in 10 patients undergoing orthotopic liver transplantation (group 1) (mean age 38 yr, mean weight 60 (SD 7) kg) and compared it with that in 10 patients without liver dysfunction undergoing extrahepatic abdominal surgery (group 2) (mean age 56 yr, mean weight 68 (11) kg). A single i.v. bolus dose of propofol 0.5 mg kg-1 was injected into a peripheral vein 5 min after the beginning of the anhepatic phase in group 1 and 60 min after the induction of anaesthesia in group 2. Arterial blood samples were obtained at 5, 10, 15, 20, 30, 40, 50 and 60 min after injection and urine samples were collected every 15 min. Propofol concentrations in whole blood and urine were measured by high performance liquid chromatography with fluorescence detection. Propofol glucuronide was measured in urine by incubation with a specific beta-glucuronidase. The area under the time-blood concentration curve from 0 to 60 min was found to be significantly greater in group 1 (13743 (2830) micrograms litre-1 h-1) than in group 2 (7992 (4895) micrograms litre-1 h-1) (P less than 0.05). Unchanged propofol was not detected in the urine of either group. No significant difference was found in the amount of propofol glucuronide excreted by patients in group 1 (457 (269) micrograms) and in group 2 (921 (672) micrograms). The presence of a propofol metabolite in urine when the liver was excluded from the circulation suggests that extrahepatic metabolism occurred.

Effect of upper abdominal surgery and cirrhosis upon the pharmacokinetics of methohexital

The pharmacokinetic profile of methohexital was studied in cirrhotic patients (n = 8), patients undergoing upper abdominal surgery (n = 8) and orthopaedic patients under general anaesthesia (n = 8). The total plasma clearance of methohexital was unchanged in cirrhotics: 54 +/- 22 l.h-1 (mean +/- s.d.) as well as in patients undergoing upper abdominal surgery: 60 +/- 14 l.h-1 in comparison to orthopaedic surgery: 70 +/- 24 l.h-1. The central volume and total volume of distribution and the distribution and elimination half-lives were similar between the three groups. Despite its hepatic dependent elimination, methohexital elimination kinetics were unchanged in patients undergoing upper abdominal surgery and in cirrhosis. Owing to the high hepatic extraction ratio of methohexital, its elimination should be influenced by the hepatic blood flow. The unchanged elimination kinetics presently observed in patients with cirrhosis or those undergoing upper abdominal surgery suggest that the hepatic blood flow is less diminished than expected in these patients.