Diffusion and precipitation processes in iron-based silica gardens.

Silica gardens are tubular structures that form along the interface of multivalent metal salts and alkaline solutions of sodium silicate, driven by a complex interplay of osmotic and buoyant forces together with chemical reaction. They display peculiar plant-like morphologies and thus can be considered as one of the few examples for the spontaneous biomimetic self-ordering of purely inorganic materials. Recently, we could show that silica gardens moreover are highly dynamic systems that remain far from equilibrium for considerable periods of time long after macroscopic growth is completed. Due to initial compartmentalisation, drastic concentration gradients were found to exist across the tube walls, which give rise to noticeable electrochemical potential differences and decay only slowly in a series of coupled diffusion and precipitation processes. In the present work, we extend these studies and investigate the effect of the nature of the used metal cations on the dynamic behaviour of the system. To that end, we have grown single macroscopic silica garden tubes by controlled addition of sodium silicate sol to pellets of iron(ii) and iron(iii) chloride. In the following, the concentrations of ionic species were measured as a function of time on both sides of the formed membranes, while electrochemical potentials and pH were monitored online by immersing the corresponding sensors into the two separated solution reservoirs. At the end of the experiments, the solid tube material was furthermore characterised with respect to composition and microstructure by a combination of ex situ techniques. The collected data are compared to the previously reported case of cobalt-based silica gardens and used to shed light on ion diffusion through the inorganic membranes as well as progressive mineralisation at both surfaces of the tube walls. Our results reveal important differences in the dynamics of the three studied systems, which can be explained based on the acidity of the metal cations and the porosity of the membranes, leading to substantially dissimilar time-dependent solution chemistry as well as distinct final mineral structures. The insight gained in this work may help to better understand the diffusion properties and precipitation patterns in tubular iron (hydr)oxide/silicate structures observed in geological environments and during steel corrosion.

[Health in prison: shared vulnerability between detainees and health professionals]. / Santé en milieu pénitentiaire: vulnérabilité partagée entre détenus et professionnels de la santé.

In prison, the health professional has to take the sanitary needs of a temporary of chronically vulnerable population. His practice has to meet laws and recommendations, as well as the field reality and its numerous constraints. This puts him in a "shared vulnerability and stigmatization". He attempts to maintain or restore a health status in a deteriorating environment, at least psychologically. He is in the penitentiary world's eye which he depends upon in many ways to achieve his mandate. His activity is scarcely known and recognised by his peers from whom he can be very out of touch. To ensure a humanistic, efficient and equivalent-of-care practice, the health professional must rely on sound knowledge of general healthcare, ethics, deontology and medical laws. Basic and continuous training is a mainspring, like networking and development of federal recommendations.

[Home-based nocturnal oxymetry by the primary care practitioner]. / Oxymétrie nocturne au cabinet du médecin de premier recours.

Sleep-related disordered breathing is frequent and associated with high morbidity and mortality, thus representing a public health problem. Sleep apnea-hypopnea syndrome (SAHS) is sorely under-diagnosed. Our questioning was about the usefulness of a home-based overnight oxymetry organised by the primary care physician (PCP) for SAHS detection. It appears from our review that patients with snoring and excessive daytime sleepiness can benefit from this tool. Oxygen desaturation index less than 5/h does not rule out SAHS but makes it very unlikely. In accordance with the symptoms, one should refer the patient for complementary investigation. Besides detection, PCP has an important role to play in partnership with the pneumologist in helping the patient to cope with his respiratory device and contributing to treatment com-

[Relevant publications in ambulatory general internal medicine in 2007]. / Médecine interne générate ambulatoire: quelques enseignements de la littérature.

Screening procedures for genital Chlamydia infection, cancer risks linked to oral contraceptives, indications and efficacy of HPV vaccination, and diagnostic tools for celiac disease in adults; these are just a few of the general practice themes that were reviewed and analysed in 2007 by residents and chief residents at the Community medicine and primary care Service of the Geneva University Hospitals. These commented summaries, intended for all our colleagues, constitute Geneva's contribution to the literature data base initiated in 2005 by chief residents in Lausanne.

Human dermal microvascular endothelial cells express inducible nitric oxide synthase in vitro.

Stimulation of inducible nitric oxide synthase with subsequent release of nitric oxide in large amounts may play a critical part either in host defense reactions or in the pathophysiology of the inflammatory response syndrome leading to septic shock. The aim of the present study was to investigate whether human dermal microvascular endothelial cells exhibit the typical characteristics of an inducible nitric oxide synthase expressing cell. A strong effect on inducible nitric oxide synthase gene expression could be detected when the cells were coincubated with the proinflammatory cytokines interferon-gamma and tumor necrosis factor-alpha with inducible nitric oxide synthase cDNA concentrations averaging 11.7 +/- 0.6 amol per microg total RNA at 24 h, and 25.0 +/- 1.4 amol per microg total RNA at 48 h, respectively. Intracellular staining with an antibody recognizing inducible nitric oxide synthase protein and subsequent analysis by flow cytometry revealed a 4-fold increase of inducible nitric oxide synthase protein in human dermal microvascular endothelial cells treated with interferon-gamma/tumor necrosis factor-alpha. This was accompanied by a significant elevation in nitrite/nitrate concentrations in the cell-free culture supernatants. Our results indicate that human dermal microvascular endothelial cells are provided with an inducible nitric oxide synthase system and can be regarded as an appropriate cell model for investigating inducible nitric oxide synthase gene expression and nitric oxide properties in microvascular endothelial cells.

Neopterin induces nitric oxide-dependent apoptosis in rat vascular smooth muscle cells.

Numerous studies indicate that proinflammatory substances like tumor necrosis factor alpha (TNF-alpha) and interferon gamma (IFN-gamma) as well as macrophage-derived neopterin are increased in atherosclerotic tissue and thus are potentially involved in the process of atherogenesis. Since apoptotic death of vascular smooth muscle cells (VSMC) is reported to occur in atherosclerotic lesions, we investigated the effects of neopterin, TNF-alpha, and IFN-gamma on apoptosis in cultured VSMC. Morphological changes characteristic of apoptosis as well as DNA fragmentation were detected in cells treated with neopterin, TNF-alpha/IFN-gamma, and neopterin + TNF-alpha/IFN-gamma. Simultaneously, neopterin, TNF-alpha/IFN-gamma, and neopterin + TNF-alpha/IFN-gamma led to inducible nitric oxide synthase (iNOS) gene expression and nitric oxide (NO) synthesis. NO generation was significantly reduced when cells were cotreated with the competitive iNOS inhibitor aminoguanidine. This was accompanied by decreased percentual apoptosis as detected by FACS analysis using all kinds of stimuli. We conclude that neopterin as well as TNF-alpha/IFN-gamma are potent mediators of apoptotic death in VSMC which is at least in part triggered by NO synthesis induced by these proinflammatory mediators.

Depot medroxyprogesterone acetate use in inner-city, minority adolescents: continuation rates and characteristics of long-term users.

OBJECTIVE: To identify continuation rates of depot medroxyprogesterone acetate (Depo-Provera) and characteristics of long-term users in a population of inner-city, minority adolescents with high pregnancy rates. DESIGN: Retrospective medical record review. SETTING: An inner-city adolescent clinic and an adolescent pregnancy program. METHODS: A review of the medical records of 250 females aged 13 to 20 years (mean +/- SD, 16.8 +/- 1.1 years), 62.9% Hispanic and 34.2% African American, receiving a first depot medroxyprogesterone acetate injection for contraception between August 1993 and June 1996 was conducted using a standardized form. The mean +/- SD age at menarche of the subjects was 11.6 +/- 1.4 years, and the mean +/- SD age at first intercourse was 14.1 +/- 1.3 years; the mean number of lifetime sex partners was 2.4. Of the subjects, 73.6% had used condoms, 32.0% used oral contraceptives, and none used implants. Of the 201 subjects for whom there were data in the medical records regarding prior fertility, 172 (85.6%) had been pregnant, and 145 (72.1%) had a child. Life table analysis was used to measure depot medroxyprogesterone acetate continuation rates and to compare subgroups of adolescents. RESULTS: Depot medroxyprogesterone acetate continuation rates were found to be 70.3% at 6 months, 48.3% at 9 months, 31.5% at 12 months, and 12.8% at 24 months. The most common reason for depot medroxyprogesterone acetate discontinuation was missed appointments (41.7%). Subjects were followed up for a mean +/- SD of 1.3 +/- 0.7 years after discontinuation of depot medroxyprogesterone acetate use; 46.7% became pregnant. Among those 156 adolescents who discontinued depotmedroxyprogesterone acetate use, 40.0% restarted the method at some later time. Continuation of depot medroxyprogesterone acetate use was more likely if age at first intercourse was younger than 13 years (P = .04). Continuation rates were not related to age, ethnicity, age at menarche, number of sex partners, use of other contraceptives, prior pregnancy, or having a child. CONCLUSIONS: In this study, just less than one third of the adolescents continued depot medroxyprogesterone acetate use for 1 year or longer. This suggests that depot medroxyprogesterone acetate does not function as a long-term method for most inner-city adolescents. The only characteristic that was associated with successful continuation of depot medroxyprogesterone acetate use was young age at first intercourse, implying that experience may be the main determinant of continuation.

Human breath isoprene and its relation to blood cholesterol levels: new measurements and modeling.

Numerous publications have described measurements of breath isoprene in humans, and there has been a hope that breath isoprene analyses could be a noninvasive diagnostic tool to assess blood cholesterol levels or cholesterol synthesis rate. However, significant analytic problems in breath isoprene analysis and variability in isoprene levels with age, exercise, diet, etc., have limited the usefulness of these measurements. Here, we have applied proton transfer reaction-mass spectrometry to this problem, allowing on-line detection of breath isoprene. We show that breath isoprene concentration increases within a few seconds after exercise is started as a result of a rapid increase in heart rate and then reaches a lower steady state when breath rate stabilizes. Additional experiments demonstrated that increases in heart rate associated with standing after reclining or sleeping are associated with increased breath isoprene concentrations. An isoprene gas-exchange model was developed and shows excellent fit to breath isoprene levels measured during exercise. In a preliminary experiment, we demonstrated that atorvastatin therapy leads to a decrease in serum cholesterol and low-density-lipoprotein levels and a parallel decrease in breath isoprene levels. This work suggests that there is constant endogenous production of isoprene during the day and night and reaffirms the possibility that breath isoprene can be a noninvasive marker of cholesterologenesis if care is taken to measure breath isoprene under standard conditions at constant heart rate.

Analysing ventricular fibrillation ECG-signals and predicting defibrillation success during cardiopulmonary resuscitation employing N(alpha)-histograms.

Mean fibrillation frequency may predict defibrillation success during cardiopulmonary resuscitation (CPR). N(alpha)-histogram analysis should be investigated as an alternative. After 4 min of cardiac arrest, and 3 versus 8 min of CPR, 25 pigs received either vasopressin or epinephrine (0.4, 0.4, and 0.8 U/kg vasopressin versus 45, 45, and 200 microg/kg epinephrine) every 5 min with defibrillation at 22 min. Before defibrillation, the N(alpha)-parameter histogramstart/histogramwidth and the mean fibrillation frequency in resuscitated versus non-resuscitated pigs were 2.9+/-0.4 versus 1.7+/-0.5 (P=0.0000005); and 9.5+/-1.7 versus 6.9+/-0.7 (P=0.0003). During the last minute prior to defibrillation, histogramstart/histogramwidth of > or =2.3 versus mean fibrillation frequency > or =8 Hz predicted successful defibrillation with subsequent return of a spontaneous circulation for more than 60 min with sensitivity, specificity, positive predictive value and negative predictive value of 94 versus 82%, 96 versus 89%, 98 versus 93% and 90 versus 74%, respectively. We conclude, that N(alpha)-analysis was superior to mean fibrillation frequency analysis during CPR in predicting defibrillation success, and distinction between vasopressin versus epinephrine effects.

Different patterns of inducible nitric oxide synthase gene expression in ovarian carcinoma cell lines.

BACKGROUND: Stimulation of inducible nitric oxide synthase (iNOS) and release of nitric oxide by tumor cells may play a critical role in cancer development, either by exhibiting tumoricidal effects or by promoting tumor progression. MATERIALS AND METHODS: In the present study, we investigated four ovarian carcinoma cell lines with respect to their iNOS expressing characteristics. RESULTS: Following incubation with interferon-gamma, tumor necrosis factor-alpha and interleukin-1 beta, a marked stimulation of iNOS gene expression was found in SKOV-6 and OVCAR-3 cells, while only minor iNOS synthesis was detectable in HOC-7. Time-dependent accumulation of nitrite/nitrate in the culture supernatant indicated that the three cell lines were stimulated to produce and release nitric oxide. In contrast, no NO generation was observed in the fourth cell line under investigation, 2774. CONCLUSION: Due to the growth regulatory functions attributed to NO, variations in NO production may be of importance e.g. following interferon-gamma therapy in patients with ovarian cancer.

The use of nonhormonal methods of contraception in adolescents.

Although the 1990s have seen a reduction in unintended pregnancy rates and improved contraceptive-use rates, the negative consequences of unintended pregnancy and STD acquisition continue to plague our youth. Primary health care providers, including pediatricians, play an essential role in further reducing unintended teen pregnancy and STD acquisition rates through the promotion of effective and consistent contraception. Pediatricians need to be aware that now, more than ever, nonhormonal contraceptive methods should be used by every sexually active youth, and counseling of both boys and girls should be routine. Although not as effective at preventing pregnancy as hormonal methods of contraception, many nonhormonal methods provide excellent STD protection. Condoms plus spermicide continue to be a very popular and effective method of pregnancy and STD prevention. The newer polyurethane male and female condoms provide alternative, safe barrier protection, although their efficacy at preventing HIV in vivo needs further study. Diaphragms and cervical caps, in conjunction with spermicide, also provide pregnancy and STD prevention, but not as effectively as male condoms plus spermicide. Although most likely to use condoms in association with another birth control method, adolescents often find dual-method use cumbersome and difficult to comply with. Finally, although IUDs and periodic abstinence are safe methods of birth control for older women in monogamous relationships, they are unlikely to be appropriate for most adolescents. In many respects, we have come full circle back to our "nonhormonal contraceptive roots." As we enter the twenty-first century, we have found that no single "miracle" approach can be used to reduce adolescent pregnancy and STD rates. Rather, pediatricians are obliged to offer nonhormonal methods of contraception, often in conjunction with other birth control methods, as a means of preventing unwanted STDs and pregnancy. Through a comprehensive community approach that uses sex education, abstinence programs, condom-availability programs, and contraceptive-skills training, however, pediatricians can play a central role in the promotion of effective and consistent contraception by adolescents.

Analysis of volatile organic compounds: possible applications in metabolic disorders and cancer screening.

The human breath contains a variety of endogenous volatile organic compounds (VOCs). The origin and pathophysiological importance of these VOCs is poorly investigated. Little is known about the interaction of VOCs from ambient air, such as those produced by plants and exhaust fumes, with the human organism. Gas chromatographic determination of VOC concentrations is tedious. Proton-transfer-mass spectroscopy (PTR-MS), a new technology for the online detection of VOC patterns, is a valuable alternative. We present two interesting molecular species, isoprene and ortho (o)-toluidine, as examples of endogenously produced VOCs. In a case study, breath isoprene reductions during lipid-lowering therapy (36%) were shown to correlate with cholesterol (32%) and LDL concentrations (35%) in blood (p < 0.001) over a period of 15 days. Therefore, isoprene concentrations in human breath (measured by PTR-MS) might serve as an additional parameter to complement invasive tests for controlling lipid-lowering therapy. Furthermore, it may be a useful parameter for lipid disorder screening. Mass-108, which presumably represents o-toluidine in our breath samples, was found in significantly higher concentrations in the breath of patients with different tumors (1.5 +/- 0.8 ppbv) than in age-matched controls (0.24 +/- 0.1 ppbv, p < 0.001). Inflammatory reactions do not seem to alter the pattern of mass-108. Therefore, it appears to be a currently underestimated carcinoma marker that deserves further investigation.

Evaluation of a rabies ELISA as an alternative method to seroneutralisation tests in the context of international trade of domestic carnivores.

For several years, international movements with pets have greatly increased. Most countries have relaxed their quarantine measures and adopted a scheme combining vaccination of pets against rabies followed by a serological test to check the efficacy of vaccination. This new scheme has been strongly supported by the OIE, WHO and the European Commission to facilitate the free movement of people and pets around the world. Currently, only two reference methods are recognised and prescribed (the FAVN test and the RFFIT) to measure rabies antibody levels in serum samples for international trade. They are reliable and valuable methods of assessing the efficacy of rabies vaccination but they are time-consuming and require well-trained people and specialised laboratory facilities. A few years ago, an ELISA (Platelia™ Rabies II kit ad usum Veterinarium) was developed for domestic carnivores and wildlife. To our knowledge, this ELISA is the only one certified and prescribed by the OIE. Following its marketing, one task of the EURL for rabies serology was to evaluate the performance of laboratories using this new kit. The results revealed that 26% of the participants, which were already approved laboratories for rabies serology, failed the inter-laboratory trial. Such unsatisfactory results have never been observed during any of the previous proficiency tests organised annually since 2000 by the EURL for rabies serology using reference methods. More investigations were undertaken through internal and collaborative studies to assess the performance of this newly marketed ELISA kit. The results of the internal study revealed that even with a specificity of 100%, the sensitivity evaluated on 593 samples of domestic carnivores came to 78.2%. An issue regarding the underestimation of serum titres was also revealed during the study. The results of a collaborative study involving 23 international laboratories reinforced the preliminary conclusions regarding lack of sensitivity. Indeed, only 5 laboratories out of the 23 obtained satisfactory results. We therefore suggest adopting a threshold of 0.3 EU/mL instead of 0.5 EU/mL to increase the sensitivity of the test.

Cisatracurium, but not mivacurium, induces apoptosis in human umbilical vein endothelial cells in vitro.

BACKGROUND AND OBJECTIVE: Cisatracurium is an intermediate acting, non-depolarizing neuromuscular blocking agent. Previous reports have indicated a growth-inhibitory effect of the isoforms cisatracurium and atracurium on two human cell lines in vitro. These effects were ascribed to oxidative stress elicited by acrylate esters formed during cisatracurium breakdown. Oxidative stress is a potent precipitator of apoptosis. Therefore, the aim of the present study was to investigate whether the growth-inhibitory effects of cisatracurium could be explained by initiation of apoptosis. METHODS: Human umbilical vein endothelial cells were incubated with cisatracurium at concentrations of 0.96, 3.2, 9.6, 32 and 96 micromol for 24 h. DNA fragmentation was measured using the Cell Death Detection ELISA Plus assay (Roche Diagnostics, Mannheim, Germany). RESULTS: There was a dose dependency of cisatracurium with respect to the rate of apoptosis in human umbilical vein endothelial cells. Programmed cell death could be demonstrated at concentrations encountered in human plasma after single-bolus injections of cisatracurium. Apoptosis was attenuated by the concomitant administration of glutathione. CONCLUSIONS: These findings strongly support the hypothesis that acrylate esters, breakdown products of cisatracurium, induce oxidative stress and, subsequently, apoptosis.

Incidence of lower thoracic ligamentum flavum midline gaps.

BACKGROUND: Lower thoracic epidural anaesthesia and analgesia (EDA) has gained increasing importance in perioperative pain therapy. The loss-of-resistance technique used to identify the epidural space is thought to rely on the penetration of the ligamentum flavum. Investigations at the cervical and lumbar regions have demonstrated that the ligamentum flavum frequently exhibits incomplete fusion at different vertebral levels. Therefore, the aim of this study was to directly investigate the incidence of lower thoracic ligamentum flavum midline gaps in embalmed cadavers. METHODS: Vertebral column specimens were obtained from 47 human cadavers. Ligamentum flavum midline gaps were recorded between the vertebral levels T6 and L1. RESULTS: The incidence of midline gaps/number of viable specimens at the following levels was: T6-7: 2/45 (4.4%), T7-8: 1/47 (2.1%), T8-9: 2/45 (4.4%), T9-10: 7/39 (17.9%), T10-11: 12/34 (35.2%), T11-12: 10/35 (28.5%), T12/L1: 6/38 (15.8%). CONCLUSIONS: In the present study we have determined the frequency of lower thoracic ligamentum flavum midline gaps. Gaps are less frequent than at cervical levels, but more frequent than at lumbar levels. Peak incidence was found in the region between T10 and T12. Using a strict midline approach, one cannot therefore rely on the ligamentum flavum to impede entering the epidural space in all patients.

Craniotomy during ECMO in a severely traumatized patient.

Extracorporeal membrane oxygenation (ECMO) can be a last resort treatment in acute respiratory distress syndrome after thoracic trauma. However, co-existent brain trauma is considered to be a contra-indication for ECMO. This is the first report on successful craniotomy under ECMO treatment in a multiply traumatized patient with severe thoracic and brain injuries. This successful treatment with beneficial neurological outcome suggests that ECMO therapy should not be withheld from severely injured patients with combined brain and thoracic trauma presenting with life-threatening hypoxemia. Moreover, even craniotomy may be performed during ECMO therapy without major bleeding and adverse effects on neurological function.

The simultaneous quantitative determination of total, 'active', acetylated and conjugated sulfonamide in biological fluids.

Methods are proposed which, in combination with those described in an earlier publication by the author, enable the separate determination of the two main types of sulfonamide metabolites, the N4-acetyl derivative and the conjugates, besides the total and the active sulfonamide in body fluids.

Update on pubertal development.

This review provides updated information relating to the timing of pubertal onset from a large study of girls seen in pediatric practices. In addition, new studies investigating the relationship of the hormone leptin to the onset of puberty are discussed, as well as new information on the neuroendocrine control of pubertal regulation. A provocative study documenting poor mental health, more behavior problems, and lower IQ in children with premature adrenarche when compared with controls raises the question of whether psychological stress triggers premature adrenarche or whether the early increase in adrenal hormone secretion causes psychosocial problems. Finally, significant advances in the management of central precocious puberty in girls have been made over the past year.