Search

Chemically modified silica is widely used as a reinforcing filler in elastomers. The modification is generally done in situ while preparing the rubber. However, in order to increase the efficiency and facilitate the mixing process, the silica can be pre-treated by a 2-step molecular layer deposition. The precursors for the modification are 3-mercaptopropyl-triethoxysilane (MPTES) and octanoyl chloride (OC) to react with MPTES and form a blocked silane. The precipitated silica nanofiller was successfully treated with MPTES and showed a self-limiting behavior: saturation occurred at 2.7%. Furthermore, DRIFTS (diffuse reflectance infrared Fourier transform spectroscopy) analysis confirmed the successful deposition of MPTES on the silica surface by showing the -SH peak that appeared after the reaction of MPTES and silica. In the second step, OC was introduced to form a thioester on the surface of the MPTES-treated silica, controlling the reactivity of the mercapto group from MPTES by blocking it to prevent a negative influence on the processing behavior of the rubber. Thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy (XPS) analytical results confirmed the deposition of the blocked mercapto silane on the silica. TGA results demonstrated the self-limiting behavior of OC, and DRIFTS and XPS proved the thioester formation. A thioester peak after the 2nd reaction step with OC appeared. At the same time, the disappearance of the -SH signal from the MPTES was observed, indicating the formation of the blocked mercapto silane structure. Transmission electron microscopy results showed that the treated silica has a well-distributed carbon and sulfur deposition after MPTES/OC treatment.

More than 40 years ago, Garvie et al. (1975) have shown that the transformation of metastable tetragonal (t) zirconia grains towards the monoclinic (m) symmetry could be at the origin of a very pow...

The processing of a new ceria-doped tetragonal zirconia polycrystal-based (Ce-TZP) composite and its microstructural and mechanical features are presented. Slip casting and die pressing were used to process commercially available Ce-TZP and MgAl 2 O 4 powders into a dense ceramic composite. The absence of tetragonal to monoclinic transformation under hydrothermal conditions was assessed during accelerated aging tests. Biaxial flexural strength and fracture toughness values of more than 900 MPa and 15 MPa √m, respectively were measured, showing that phase transformation toughening of zirconia is maintained in the composite, while the inter/intragranular dispersion of nano-scaled magnesia spinel leads to strengthening of the Ce-TZP matrix. Flaw tolerance is attained, since the strength appears to be transformation dependent. These properties allow the composite to be used in the fabrication of various load-bearing components by employing conventional processing methods and sintering, for example for structural biomedical applications.

Resume Les troubles du langage et de la communication sont un des criteres diagnostiques des troubles autistiques. Du fait de l’elargissement du concept d’autisme incluant des formes moins severes, on ne retrouve pas de tableau unique mais des profils langagiers varies. Un bilan precis des capacites langagieres et des fonctions de communication est necessaire a toute prise en charge educative ou reeducative de l’enfant atteint d’autisme. Les donnees de la litterature appliquees a l’etude de la parole des enfants autistes sont ici confrontees a nos observations cliniques.

Background: In Peru a previous study of government-sponsored periodic examinations of female sex workers (FSWs) found no significant impact on rates of sexually transmitted diseases (STDs). Goal: This study assessed the impact of technically improved periodic STD services on STD prevalence and on consistent condom use (CCU). Study Design: The study involved monthly follow-up of 917 FSWs at two STD clinics with evaluations before and during implementation of strengthened STD services which included periodic screening and treatment for gonorrhea chlamydial infection trichomoniasis bacterial vaginosis (BV) and syphilis; counseling; and supply of condoms. Outcome analyses were adjusted for participation bias. Results: During 7908 person-months of observation the prevalences of gonorrhea chlamydial infection trichomoniasis and BV declined significantly and CCU increased significantly with similar trends in both clinics. During follow-up gonorrhea chlamydial infection trichomoniasis and BV were negatively associated with follow-up after screening. BV also was positively associated with use of an intrauterine device and negatively with douching. CCU during follow- up was associated with significantly decreased risk of gonorrhea chlamydial infection and trichomoniasis. Conclusions: Strengthened periodic screening for and treatment of confirmed STD in addition to condom promotion and provision represent feasible effective interventions in commercial sex and time series analyses can provide a useful approach to evaluating new interventions. (authors)

Human T cell lymphotropic virus type I (HTLV-I) is sexually transmitted. The purpose of this study was to determine the prevalence and risk factors for cervical shedding of HTLV-I DNA among Peruvian sex workers. HTLV tax DNA was detected in cervical specimens from 43 (68%) of 63 HTLV-I-infected sex workers and in samples obtained during 113 (52%) of 216 clinic visits between 1993 and 1997. Detection of HTLV DNA was associated with the presence of > or =30 polymorphonuclear cells (PMNs) within cervical mucus per 100x microscopic field (odds ratio [OR], 4.3, 95% confidence interval [CI], 1.8-10.1) and with the presence of cervical secretions (OR, 2.0; 95% CI 1.2-3.4). Hormonal contraceptive use (OR 1.7; 95% CI, 0.8-3.6) and concomitant cervical infection by Chlamydia trachomatis (OR, 1.5; 95% CI, 0.3-4.3) or Neisseria gonorrhoeae (OR, 1.1; 95% CI, 0.6-3.7) were not significantly associated with HTLV-I shedding. Our results suggest that cervicitis may increase cervical HTLV-I shedding and the sexual transmission of this virus.

Objectives: To determine age-specific seroprevalence, risk factors, and risk markers for heterosexually-acquired HIV infection among pregnant women. Design: Cross-sectional study of 12 436 consecutive pregnant women in Lima, Peru in 1996-1997. Methods: Standardized interviews, serologic tests for HIV and syphilis, bivariate and multivariate analysis. Results: HIV seropositivity was confirmed in 58 women (0.5%). Only 22.6% were married, and only 12% of HIV infected women reported ≥2 sex partners ever. In multivariate analyses HIV infection was associated with: short duration of current relationship; two risk behaviors of women themselves (early onset of sexual activity and number of past sexual relationships); women's perceptions of two risk behaviors of partners (partner is a 'womanizer,' and partner uses illegal drugs); inadequate prenatal care; and four additional risk factors or markers (history of sexually transmitted disease, tuberculosis, or abortion in the women; and diagnosis of HIV/AIDS in a partner). Conclusions: HIV infection was related both to women's own risk behaviors and to the perceived risk behaviors of their sexual partners. Underlying societal factors related to heterosexual HIV infection, including deferral of marriage, warrant further study.

We have examined the respective influence of aldosterone, vasopressin and cell sodium delivery on Na+,K+-ATPase expression. The level of expression of the mRNA encoding for the alpha1- and beta1-subunits of Na+,K+-ATPase was evaluated in cortical collecting duct (CCD) cells from rats under different aldosterone status, in cells from the rat CCD cell line RCCD1 treated or not with vasopressin and in CCD cells from mice inactivated or not for the a-subunit of the epithelial sodium channel. The amount of mRNA was determined by in situ hybridization. Both aldosterone and vasopressin up-regulate transcripts encoding for the alpha1-subunit of Na+,K+-ATPase while beta1 is unaltered. Interestingly, when cell sodium entry was largely reduced (alphaENaC knock-out mice), the amount of transcripts encoding for the alpha1-subunit of Na+,K+-ATPase was significantly decreased in spite of high plasma aldosterone concentrations. No effect was observed on beta1-subunit. Altogether, these results suggest a coordinated hormonal and ionic control of Na+,K+-ATPase expression by different transcriptional pathways (steroid-receptor, cAMP-dependent and Na+dependent) in CCD cells. These regulations affect only alpha1-subunit of Na,K+-ATPase but not beta1.

To identify clinical epidemiological correlates of cervical and vaginal infections and assess alternative algorithms, including two new reproductive tract infection (RTI) algorithms, for syndromic management of these infections.We prospectively studied clinical manifestations and risk correlates of cervical and vaginal infections in a randomly sampled group of 779 female patients seeking evaluation for a new problem at a Seattle STD clinic.One experienced clinician performed standardised history, physical examination, and microscopy. Reference laboratories performed microbiological tests. Three levels of retrospective evaluation of algorithms included risk assessment and symptom review (RAS) alone; addition of speculum and bimanual examinations; and further addition of microscopy.(1) Chief complaint of abnormal vaginal discharge predicted a significantly lower rate of gonorrhoea (GC) or chlamydial infection (CT) than rates observed with no complaint of vaginal discharge. Only the elicited symptom of yellow vaginal discharge (not the more common symptoms of increased or malodorous vaginal discharge) predicted GC or CT. Chief complaint of abnormal vaginal discharge itself predicted trichomoniasis (TV) and bacterial vaginosis (BV), not cervical infection. Candida albicans was strongly associated with the chief complaint of vulvar pruritus, not with the chief complaint of abnormal vaginal discharge. (2) Applying these algorithms in STD clinics only to women with the chief complaint of abnormal vaginal discharge, rather than to all women, decreases sensitivity for GC or CT, without increasing positive predictive value (PPV). Criteria for inclusion of patients have more effect on the performance of these algorithms than do the levels of evaluation used. (3) A modified World Health Organisation (WHO) algorithm applied only to patients with symptoms of vaginal discharge, involving treatment of RAS positives for cervical infection, followed by treatment of vaginal infections and cervicitis based on examination of RAS negatives and positives, had a sensitivity of 50% and PPV of 33% for cervical infection, and very low sensitivity for BV, TV, and for vulvovaginal candidiasis (VVC). (4) An RTI algorithm derived from these data, and applied to all STD patients, involving RAS and examination of all RAS negatives, provided treatment to all cases of BV and TV associated with symptoms of vaginal discharge; treatment of all VVC associated with symptoms of vulvar pruritus; treatment for GC and GT to all RAS positives (using easily elicited risk factors) and to RAS negatives with signs of cervicitis or PID. This algorithm had a sensitivity of 87% and a PPV of 33% for GC or CT in this population, with its 24% prevalence of GC or CT. The sensitivity for BV, TV, and VVC greatly exceeded that of the modified WHO algorithm. (5) A modified RTI algorithm, involving examination rather than treatment of RAS positive women, no examination of RAS negatives, decreased the sensitivity for cervical infection to 55% but increased the PPV to 51%.Syndromic management of vaginal discharge offers relief of symptoms, prevention of transmission of trichomonas, and perhaps prevention of complications of BV. The 51% PPV of the modified RTI algorithm probably would warrant treatment and partner notification for GC and CT in settings with similar rates of GC and CT where more specific tests are lacking. However, as the prevalence of GC or CT decreases, the ratio of uninfected to infected who receive treatment with these algorithms would increase greatly, making the algorithms potential victims of their own success.

Introduction We report an incidental finding of a 9.8 cm Crawford type III thoraco-abdominal aortic aneurysm associated with autosomal dominant polycystic kidney disease (ADPKD). Case report CT imaging revealed a grossly enlarged polycystic liver and right kidney in a 54-year-old female. The patient had a complex medical history including end-stage renal failure requiring haemodialysis and chronic obstructive pulmonary disease. She had experienced back pain for eighteen months. This was attributed to a progression of pain secondary to abdominal polycystic disease and therefore not investigated. She had previously undergone a left nephrectomy. A single-stage hybrid approach with open retrograde visceral re-vascularisation and endovascular stenting was carried out successfully to treat the aneurysm. Discussion We report this case to highlight the association between aortic aneurysms and ADPKD, and we present a solution to the complex technical problem involved.

Objectifs Evaluer la fiabilite de l’angioscanographie fonctionnelle dans la detection d’une HTAP. Materiels et methodes Vingt patients ayant beneficie d’un catheterisme cardiaque droit (12 patients sans HTAP ; PAP moyenne : 16,4 mmHg) (8 patients avec HTAP ; PAP moyenne : 36,75 mmHg) ont ete explores par angioscanographie multicoupe (64 coupes/rotation) du thorax avec synchronisation cardiaque et etude de la chambre de chasse du ventricule droit (VD) et de l’artere pulmonaire droite (APD) en reconstructions 2D systoliques et diastoliques. Resultats Quatre parametres ont des valeurs significativement differentes en presence d’une HTAP : le diametre du tronc pulmonaire (p = 0,03), l’epaisseur diastolique (p = 0,04) et systolique (p = 0,008) du myocarde ventriculaire droit et la distensibilite de l’APD (0,007) avec etablissement d’un seuil predictif d’HTAP pour chacune des variables (tronc AP : 31,65 mm-specificite : 100 % ; epaisseur diastolique du VD : 4,85 mm-specificite : 92 % ; epaisseur systolique du VD : 6,75 mm-specificite : 92 % ; distensibilite de l’APD : 16 %-specificite : 100 %). La distensibilite de l’APD est le parametre ayant la meilleure correlation avec les valeurs de pression arterielle pulmonaire moyenne (r = -0,7 ; p Conclusion L’angioscanographie fonctionnelle peut permettre une approche non invasive de l’HTAP.