Inhibition of prolactin-induced mammary cancer in C3Hf (XVII) mice with the trans isomer of bromotriphenylethylene.

C3Hf (XVII) mice never develop spontaneous mammary tumors. However, the transplantation of an isologous pituitary gland under their kidney capsule is followed by a 10-fold increase in serum and pituitary prolactin content (180 ng/ml and 20 micrograms/mg of tissue, respectively), concomitant with an increase of prolactin receptors in mammary glands. Under these conditions, mammary tumors appear in 90% of the mice. If a racemic brominated triphenylethylene, i.e., broparestrol, is administered, serum and pituitary prolactin decrease rapidly (10 ng/ml and 4 micrograms/mg of tissue, respectively), and prolactin receptors in the mammary gland are markedly reduced. This compound also inhibits the development of normal mammary glands, prevents mammary carcinogenesis, and unexpectedly causes a significant atrophy of the ovaries. Our study confirms that prolactin is a key hormone involved in murine mammary carcinogenesis and that it can act directly on the mammary gland by stimulaing the level of its own receptor.

Integrated kinetics of X chromosome inactivation in differentiating embryonic stem cells.

Inactivation of the X chromosome during early female development and the subsequent maintenance of this transcriptionally inert state through countless cell divisions remain a paradigm for epigenetic regulation in mammals. Nevertheless, the exact mechanisms underlying this chromosome-wide silencing process remain unclear. Using differentiating female embryonic stem (ES) cells as a model system, we recently found that histone H3 tail modifications are among the earliest known chromatin changes in the X inactivation process, appearing as soon as Xist RNA accumulates on the X chromosome, but prior to transcriptional silencing of X-linked genes (Heard et al., 2001). In this report we present an integrated analysis of the sequence of early events and chromatin modifications underlying X inactivation in differentiating female ES cells. We have extended our previous analysis concerning changes in histone tail modification states. We find that the hypomethylation of Arg-17 and that of Lys-36 on histone H3 also characterize the inactive X chromosome, and that these profiles show a similarly early onset during the initiation of X inactivation. In addition, we have investigated the kinetics of the shift in replication timing of the X chromosome undergoing inactivation. This event occurs slightly later than Xist RNA coating and the chromatin modifications. Finally, from an early stage in the X inactivation process, characteristic histone modification patterns can be found on the X chromosome at mitosis, suggesting that they represent true epigenetic marks of the inactive state.

Effects of the lipophilic biscation, bis-pyridinium oxime BP12, on bioenergetics and induction of permeability transition in isolated mitochondria.

In order to further investigate the mechanism of action of bridged lipophilic bis-pyridinium oximes previously observed to interfere with mitochondrial metabolism and to induce growth arrest and apoptosis in HeLa cells (Nocentini et al., Biochem Pharmacol 53: 1543-1552, 1997), we studied the effects of a bis-pyridinium oxime with a polymethylene chain N = 12 (BP12) on isolated rat liver mitochondria. Respiration in the absence of ADP with succinate plus rotenone as substrate was not affected after treatment with various concentrations of BP12 up to 10 microM, while the ADP-stimulated respiration was slowed down, with a parallel decrease in ATP synthesis. No effects of BP12 were detected on membrane potential, ATPase activity, and inorganic phosphate transport, but the adenine nucleotide translocase was inactivated and a permeability transition of the inner membrane was induced in the presence of calcium. These data suggest that mitochondrial impairment of ATP synthesis and the formation of the permeability transition pore may be responsible for apoptotic cell death already observed in cells treated with BP12.

Induction of mitochondrial dysfunction and apoptosis in HeLa cells by bis-pyridinium oximes, a newly synthesized family of lipophilic biscations.

When tested on HeLa cells, bis-pyridinium oximes (BPO), a family of newly synthesized molecules whose charged pyridinium moieties are linked by a linear polymethylene chain of variable length (N = 3 to 12) have been shown to possess an inhibitory effect on cell growth and finally to provoke cell death. BPO-affected cells displayed reduced mitochondrial oxygen consumption and ATP stores and were blocked in the G1 phase of the cell cycle. Mitochondrial membrane potential, as assayed with the dye 3,3'-diexyloxacarbocyanine iodide [DiOC6(3)], increased in BPO-treated cells with time of exposure. Cell growth inhibition as well mitochondrial dysfunction were observed only with derivatives having a long polymethylene linking chain (N > or = 6). Furthermore, the concentration of the compound eliciting such effects was inversely related to the number of methylene groups in the linking chain. None of the BPO with N = 6 to 12 modified the mitochondrial DNA content, relative to the nuclear DNA content. In BPO (N = 8 and N = 12)-treated cells, chromatin fragmentation and internucleosomal DNA cleavage occurred massively, indicating that the death mode induced by these compounds is apoptosis. The possible pathway of action and the potential pharmacological interest of these compounds are discussed.

Exacerbating effect of vitamin E supplementation on DNA damage induced in cultured human normal fibroblasts by UVA radiation.

The effects of vitamin E supplementation were evaluated in cultured human normal fibroblasts exposed to ultraviolet A radiation (320-380 nm) (UVA). Cells were incubated in medium containing alpha-tocopherol, alpha-tocopherol acetate or the synthetic analog Trolox for 24 h prior to UVA exposure. DNA damage in the form of frank breaks and alkali-labile sites, collectively termed single-strand breaks (SSB), was assayed by the technique of single cell gel electrophoresis (comet assay), immediately following irradiation or after different repair periods. The generation of hydrogen peroxide (H2O2) and superoxide ion (O2.-) was measured by flow cytometry through the oxidation of indicators into fluorescent dyes. It was observed that pretreatment of cells with any form of vitamin E resulted in an increased susceptibility to the photoinduction of DNA SSB and in a longer persistence of damage, whereas no significant change was observed in the production of H2O2 and O2.- reactive oxygen species, compared to untreated controls. These findings indicate that in human normal fibroblasts, exogenously added vitamin E exerts a promoting activity on DNA damage upon UVA irradiation and might lead to increased cytotoxic and mutagenic risks.

Isomers of broparoestrol and antiestrogen action: comparison with tamoxifen.

This study compares the relative biological potencies of a known antiestrogen tamoxifen to two triarylethylene compounds which have been shown previously to be potent inhibitors of rodent mammary tumorigenesis. Based on a) uterotrophic and anti-uterotrophic tests, b) indexes of cellularity, and c) protein content, these studies indicate that the trans, as well as the cis, isomers of bromotriphenylethylene are partial estrogen antagonists with no estrogenic effects in rat uteri and partial agonists in mouse uteri, whereas tamoxifen shows partial antiestrogenic/estrogenic effects in rats and is fully estrogenic in mice.

[Prevalence of patent foramen ovale in young patients with ischemic cerebral complications]. / Prévalence du foramen ovale perméable chez les patients jeunes atteints d'accident ischémique cérébral.

We compared the prevalence of patent foramen ovale (PFO), detected by two-dimensional contrast echocardiography, in a group of 60 adults aged under 55 who had experienced a cerebral ischaemic accident and had normal standard examination of the heart, and in a control group of 100 patients. The prevalence of PFO was significantly higher in neurological patients (40 p. 100) than in controls (10 p. 100; p less than 0.001). Within the neurological group, the prevalence of PFO determined blindly, i.e. without any knowledge of the aetiological diagnosis, increased with the uncertainty of diagnosis: 21 p. 100 when a cause could be determined (n = 19), 40 p. 100 when a facilitating factor of cerebral accident, such as mitral valve prolapse, migraine or consumption of oral contraceptives, could be identified (n = 15), and 54 p. 100 when neither cause nor facilitating factor could be found (n = 26; p less than 0.10). In view of the very high prevalence of clinically silent venous thrombosis, these results suggest that paradoxical embolism through a PFO might be responsible for cerebral ischaemic accidents more frequently than is generally believed.

[The injured brain. Basis for hydroelectrolytic and hemodynamic resuscitation]. / Le cerveau lésé. Bases de la réanimation hydroélectrolytique et hémodynamique.

Brain insult in neurosurgical patients is highly dependent on hydroelectrolytic and haemodynamic disturbances. The magnitude of their effect is related to blood-brain barrier integrity and characteristics of cerebral perfusion pressure. Moderate disturbances in ionic balance or CPP may lead to interstitial oedema or worsening of cerebral ischaemia. As a consequence, intracranial pressure (ICP) may rise and neurological status worsen. This study discusses the cerebral effects of intercompartimentary water and electrolyte movements, which themselves are either secondary to early neurological dysfunction, as insipid diabetes, the syndrome of inappropriate ADH secretion, and/or to renal losses of sodium, or iatrogenic, after administration of mannitol or furosemide. Understanding the early mechanism underlying these disorders is essential for treatment. Early interstitial oedema is mainly a consequence of low plasma osmolality, whereas low oncotic pressure plays a minor role. Worsening of cerebral ischemia by hyperglycaemia should contra-indicate glucose for perioperative infusion. Keeping CPP at normal levels is essential, especially in case of disturbances of the autoregulation of the cerebral circulation. Normovolaemia and the choice of an appropriate agent for plasma volume expansion are essential. Correction of hypovolaemia is best obtained with (except for packed red cells when necessary) normal saline, 4% human albumin or hydroxyethylstarch. The benefit of utilizing hypertonic electolytic or HES solutions in neurosurgical patients has still to be assessed.

[A case of spinal extradural hematoma during the insertion of an epidural catheter]. / Un cas d'hématome extradural rachidien au cours de la mise en place d'un cathéter péridural.

An epidural haematoma was observed after epidural lumbar puncture in a 75-year old patient receiving 5,000 units calcium heparinate every 12 h as antithrombotic therapy. The diagnosis was suspected by the occurrence of sudden pain and bleeding through the epidural catheter, followed by a complete paraplegia. The diagnosis was confirmed by contrast myelography. Early surgery did not improve the neurological deficit. This case report emphasized that anticoagulant therapy must be discontinued before epidural anaesthesia.

[Hemodynamic effects of atracurium in man]. / Effets hémodynamiques de l'atracurium chez l'homme.

Haemodynamic effects of atracurium at three doses (0.2, 0.6 and 1.2 mg . kg-1) were studied in thirty patients, anaesthetized with thiopentone (5 mg . kg-1) and fentanyl (0.2 microgram . kg-1 . min-1). No cardiovascular side-effects were observed with doses of 0.2 and 0.6 mg . kg-1. However, a 1.2 mg . kg-1 dose induced a transient but significant decrease in mean arterial pressure (-10%; p less than 0.001), maximal in the second minute, associated with an increase in heart rate (+10%; p less than 0.001) and cardiac index (+9%), and a decrease in systemic vascular resistance (-16%; p less than 0.001). The decrease in arterial pressure was constant in every patient and associated with a generalized flush in one of them. Histamine-release induced by atracurium may be one of the possible mechanisms involved in this hypotension.

[Detection by contrast ultrasonography of patent foramen ovale before neurosurgery]. / Détection par échographie de contraste d'un foramen ovale perméable avant neurochirurgie.

Air embolism may occur during neurosurgery if performed in the seated position. Paradoxical systemic air embolism represents a potentially severe complication in case of patent foramen ovale. Contrast echocardiography detected such a malformation in 10/100 patients, which contra-indicated the sitting position in these 10 patients. No episode of paradoxical air embolism was observed in the 90 remaining patients, although 16 cases of pulmonary air embolism were detected during surgery.

[Hemodynamic effects of vecuronium in man]. / Effets hémodynamiques du vécuronium chez l'homme.

The cardiovascular effects of vecuronium (Organon NC 45 or Norcuron) in man were determined through different protocols using continuous recording of heart rate, arterial blood pressure and parameters obtained by a Swan-Ganz catheter. In healthy anaesthetized patients (n = 23), the effects of a dose of 0.1 mg X kg-1 pancuronium (group A) were compared to those of two doses of vecuronium: 0.1 mg X kg-1 (group B) and 0.3 mg X kg-1 (group C). Pancuronium induced an increase in heart rate (+12%), arterial pressure (+16%) and cardiac index (+8%). No change occurred with vecuronium. In patients under mechanical ventilation in an intensive care unit, we compared the effects of pancuronium 0.1 mg X kg-1 (group D; n = 10), d-tubocurarine (group E; n = 11), vecuronium 0.1 mg X kg-1 (group F; n = 9) and 0.3 mg X kg-1 (group G; n = 10). Pancuronium induced an increase in heart rate (+12%), arterial pressure (+8%) and cardiac index (+9%). d-Tubocurarine induced an increase in heart rate (+6%), a decrease in arterial pressure (-24%) and cardiac index (-17%). No change was observed after vecuronium 0.1 mg X kg-1. After vecuronium 0.3 mg X kg-1, the changes were minimal: a slight decrease in arterial pressure (-5%), a very slight (+3%) and transient (3 min) increase in heart rate were observed. The doses were approximately equipotent in groups A, B and C, whereas the dose of 0.3 mg X kg-1 in group G is about 10 times the 90% effective dose of vecuronium. In geriatric patients with per- or postoperative circulatory deficiency (group H; n = 10, mean age 83 yr), no hemodynamic side effects were observed. Vecuronium seems to be a non-depolarizing neuromuscular blocking agent devoid of cardiovascular side-effects at the generally usual doses.

[Prognostic value of cerebrospinal fluid fibrinolytic activity in meningeal hemorrhages as a result of aneurysm rupture]. / Intérêt pronostique de l'activité fibrinolytique du l.c.r. dans les hémorragies méningées par rupture anévrysmale.

26 patients with subarachnoid hemorrhage from ruptured cerebral aneurysms have been reviewed. Fibrinolytic activity of the C.S.F. has been evaluated by the dosage of Fibrin/Fibrinogen degradation products (F.D.P.). When patients have developed clinical signs of ischemia, F.D.P. levels were significantly higher than in those without neurological deficit. Even, if the detection of F.D.P. seems directly correlated to the presence of blood in the C.S.F., there is no direct relation between their level and the importance of S.A.H. as shown by C.T. scan. However when F.D.P. levels are greater than 80 mcg/ml, there is a high risk of vasospasm with clinical signs.

Sensing X chromosome pairs before X inactivation via a novel X-pairing region of the Xic.

Mammalian dosage compensation involves silencing of one of the two X chromosomes in females and is controlled by the X-inactivation center (Xic). The Xic, which includes Xist and its antisense transcription unit Tsix/Xite, somehow senses the number of X chromosomes and triggers Xist up-regulation from one of the two X chromosomes in females. We found that a segment of the mouse Xic lying several hundred kilobases upstream of Xist brings the two Xics together before the onset of X inactivation. This region can autonomously drive Xic trans-interactions even as an ectopic single-copy transgene. Its introduction into male embryonic stem cells is strongly selected against, consistent with a possible role in trans-activating Xist. We propose that homologous associations driven by this novel X-pairing region (Xpr) of the Xic enable a cell to sense that more than one X chromosome is present and coordinate reciprocal Xist/Tsix expression.

Mammary carcinogenesis in (C3H X RIII) F1 mice under different experimental conditions.

In (C3H X RIII) F1 females a disturbed hormonal balance plays the major role for the etiology of mammary carcinomas. Castration early in life delays the appearance of the tumors. In normal females the adrenal secretions do not intervene in carcinogenesis. In forced bred females or in animals with pseudopregnancies, but not in mothers which nursed their offspring the latencies are shortened. After a graft with one male pituitary to a castrated female the latency is the same as in intact animals. Pituitary grafting to castrated males does not change the frequency or the latencies of spontaneous mammary cancers. One mammary cancer was observed in an intact male implanted with a pituitary. It is stated that in our animal model progesterone is not an essential factor for mammary carcinogenesis.

[Intravenous nimodipine in the treatment of cerebral vasospasm following subarachnoid hemorrhage caused by aneurysm rupture: a comparative multicenter study]. / Nimodipine intraveineuse dans le traitement curatif du vasospasme cérébral secondaire aux hémorragies méningées par rupture anevrysmale: étude comparative multicentrique.

The efficacy of intravenous Nimodipine (used at the rate of 2 mg.h-1) was investigated in the treatment of delayed ischemic deterioration or angiographic vasospasm after subarachnoid haemorrhage caused by a ruptured aneurysm in a randomized, double-blind, placebo-controlled multicenter study. A total of 127 case reports was validated: 73 patients received Nimodipine, 54 received placebo. The two groups were comparable in demographic and clinical status data. Analysis of number of deaths and of patients with severe deficit related to vasospasm alone showed a significant statistical difference (Nimodipine = 19%; Placebo = 49%; p = 0.01). The risk of mortality connected with vasospasm was reduced by 82% in the treated group. Side effects were equally frequent in the two groups. The only difference noted was the increase in heart rate in group Nimodipine. The results of this study demonstrate the efficacy of intravenous Nimodipine in the treatment of consequences of cerebral vasospasm after a subarachnoid haemorrhage caused by a ruptured aneurysm.

Mammary carcinogenesis in (C3H x RIII)F1 mice which receive the trans isomer of a brominated triphenylethylene.

The trans isomer of a bromotriphenylethylene (TBP) inhibits spontaneous mammary carcinogenesis in (C3H x RIII)F1 females, which received a diet containing 20 ppm of the chemical: intact, spayed, and spayed and pituitary implanted animals. Mammary carcinogenesis is inhibited even if the administration of the compound starts late in life. TBP has no activity on mammary carcinogenesis of castrated males implanted with an ovary.

[Inhibition of mammary carcinogenesis of C3H/f mice with broparestrol]. / Inhibition de la cancérogenèse mammaire des souris C3H/f à l'aide du broparestrol.

Administration of bromotriphenylethylene to C3H/f female mice implanted with a pituitary under the kidney capsule produce an inhibition of mammary carcinogenesis with high doses (20 ppm or 200 ppm in the diet). With a diet containing 2 ppm no inhibition is observed.

Inhibition of the development of the mammary glands of mice with a bromotriphenylethylene.

Administration of a bromotriphenylethylene to C3H/f(XVII/G) female mice implanted with a pituitary under the kidney capsule produces with high doses (200 mg/kg or 20 mg/kg of diet) a strong inhibition of the development of the mammary glands. With a low dose (2 mg/kg) no inhibition was observed. In mice which received the high doses no hyperplastic alveolar nodules were observed. The activity of the compound is more pronounced after 50 days than after 25 days.