Bone apposition to a titanium-zirconium alloy implant, as compared to two other titanium-containing implants

Implants made of commercially pure titanium (cpTi) are widely and successfully used in dentistry. For certain indications, diameter-reduced Ti alloy implants with improved mechanical strength are highly desirable. The aim was to compare the osseointegration of titanium-zirconium (TiZr) and cpTi implants with a modified sandblasted and acid-etched (SLActive) surface and with a Ti6Al4V alloy that was sand-blasted and acid-washed. Cylindrical implants with two, 0.75 mm deep, circumferential grooves were placed in the maxilla of miniature pigs and allowed to heal for 1, 2, 4 and 8 weeks. Undecalcified toluidine blue-stained ground sections were produced. Surface topography, area fraction of tissue components, and bone-to-implant contact (BIC) were determined. All materials showed significantly different surface roughness parameters. The amount of new bone within the implant grooves increased over time, without significant differences between materials. However, BIC values were significantly related to the implant material and the healing period. For TiZr and cpTi implants, the BIC increased over time, reaching values of 59.38 % and 76.15 % after 2 weeks, and 74.50 % and 84.67 % after 8 weeks, respectively. In contrast, the BIC for Ti6Al4V implants peaked with 42.29 % after 2 weeks followed by a decline to 28.60 % at 8 weeks. Significantly more surface was covered by multinucleated giant cells on Ti6Al4V implants after 4 and 8 weeks. In conclusion, TiZr and cpTi implants showed faster osseointegration than Ti6Al4V implants. Both chemistry and surface topography might have influenced the results. The use of diameter-reduced TiZr implants in more challenging clinical situations warrants further documentation in long-term clinical studies.

Liquid-state carbon-13 hyperpolarization generated in an MRI system for fast imaging

Hyperpolarized (HP) tracers dramatically increase the sensitivity of magnetic resonance imaging (MRI) to monitor metabolism non-invasively and in vivo. Their production, however, requires an extra polarizing device (polarizer) whose complexity, operation and cost can exceed that of an MRI system itself. Furthermore, the lifetime of HP tracers is short and some of the enhancement is lost during transfer to the application site. Here, we present the production of HP tracers in water without an external polarizer: by Synthesis Amid the Magnet Bore, A Dramatically Enhanced Nuclear Alignment (SAMBADENA) is achieved within seconds, corresponding to a hyperpolarization of ∼20%. As transfer of the tracer is no longer required, SAMBADENA may permit a higher polarization at the time of detection at a fraction of the cost and complexity of external polarizers. This development is particularly promising in light of the recently extended portfolio of biomedically relevant para-hydrogen-tracers and may lead to new diagnostic applications.

Hyperpolarized MRI uses molecules with a nuclear spin polarization beyond the thermodynamic equilibrium to enhance imaging contrast. Here, Schmidt et al. enable a single MRI system to both generate a hyperpolarized tracer and perform imaging, eliminating the need for an external polarizer.

Studies on the role of tetrazole in the activation of phosphoramidites

The mechanism of the tetrazole-activated coupling step in the synthesis of oligonucleotides via phosphoramidites is studied with the help of model reactions: Treatment of diethoxydiisopropylaminophosphane with two equivalents of tetrazole resulted in a diethoxy-tetrazolophosphane, whose (31P)-NMR shift of 126 ppm is identical with the signal observed during internucleotide bond formation. A series of different related diethoxy-phosphorous-acid derivatives were also synthesized; their (31P)-NMR signals between 123.9 and 130.8 ppm are additional evidence for the intermediacy of a tetrazolide species. Further NMR investigations with more basic azoles showed that tetrazole is also active as a proton donor.

Interleukin-6 is inhibited by glucocorticoids and stimulates ACTH secretion and POMC expression in human corticotroph pituitary adenomas

Interleukins and their receptors are expressed intrinsically in the anterior pituitary and regulate hormone production and cell proliferation. It has previously been shown that interleukin-6 (IL-6) regulates hormone secretion in normal pituitary cells and cell lines. Here we examined the effects of IL-6 on propiomelanocortin (POMC) expression and ACTH production in corticotroph adenoma cells in vitro. We found that IL-6 stimulates both ACTH secretion and POMC gene expression in corticotroph adenoma cell cultures. This first demonstration of the stimulatory action of IL-6 on human corticotroph adenoma cell function provides further evidence for a direct action of IL-6 on corticotroph pituitary cells. We have confirmed previous reports of IL-6 production by corticotroph adenoma cells and in addition, demonstrated for the first time that the synthetic glucocorticoid dexamethasone is a potent suppressor of intratumoral IL-6 production. This intratumoral produced IL-6 may be in part responsible, in an autocrine manner, for the stimulation of ACTH synthesis and secretion. Our results suggest that IL-6 might play a role in the pathogenesis of Cushing's disease. However, elevated glucocorticoid levels in patients with Cushing's disease may prevent excessive action of IL-6 on ACTH production and tumor progression of corticotroph adenomas in vivo.

Molecular assembly and self-assembly: molecular nanoscience for future technologies

In this review the emerging science of single molecules is discussed in the perspective of nanoscale molecular functions and devices. New methods for the controlled assembly of well-defined molecular nanostructures are presented: self assembly and single molecular positioning. The observation and selective modification of conformation, electronics, and molecular mechanics of individual molecules and molecular assemblies by scanning probes is demonstrated. To complement this scientific review, some of the possible consequences and visions for future developments are discussed, as far as they derive from the presented systems. The prospects of nanoscale science to stimulate technological evolution are exemplified.

Estradiol Stimulates Vascular Endothelial Growth Factor and Interleukin-6 in Human Lactotroph and Lactosomatotroph Pituitary Adenomas

Estrogens are considered to be critically involved in lactotroph and lactosomatotroph pituitary tumor development. In addition to direct effects, estradiol-induced tumor formation may involve alterations in growth factor and cytokine production. We have studied whether estradiol stimulates the production of the angiogenic vascular endothelial growth factor and the potential tumor progression factor interleukin-6 in 5 lactotroph (LA) and 5 lactosomatotroph (LSA) human pituitary adenoma cell cultures. All tumors secreted heterogenous basal amounts of VEGF (18.0 +/- 1.4 to 425 +/- 26 pg/ml per 24 h) and IL-6 (18.1 +/- 1.5 to 604 +/- 17 pg/ml per 24 h). Estradiol (100 nM) significantly enhanced VEGF release in all LA and LSA cell cultures (47 to 168 % above basal). IL-6 secretion was stimulated in 3 out of 5 LA and in all LSA cell cultures (31 to 287 % above basal). In cell cultures obtained from tumors from which sufficient cells could be isolated, a dose-dependent effect of estradiol (1 to 100 nM) on VEGF and IL-6 production was observed. Stimulation of IL-6 and/or VEGF secretion by estradiol in the majority of human lactotroph and lactosomatotroph adenoma cell cultures studied, suggests that estrogens may contribute to adenoma expansion through the stimulation of these auto-/paracrine-acting adenoma progression factors.

First metacarpal resurfacing with polyvinyl alcohol implant in osteoarthritis: preliminary study

Osteoarthritis of first carpometacarpal (CMC) joint is a condition that is frequently encountered in hand surgery. If conservative treatment fails, several surgical procedures are available ranging from arthroscopic debridement to total joint arthroplasty. This study focuses on a new resurfacing technique for the base of the first metacarpal using a polyvinyl alcohol hydrogel implant. Our preliminary study found good clinical outcomes and no inflammatory reaction after a follow-up of 30 months. However prospective studies with a longer follow-up and more patient are needed to confirm these results.

[Cardiovascular morbidity in patients with obstructive sleep apnea in relation to the severity of respiratory disorder]

BASIC PROBLEM AND OBJECTIVE

Untreated patients with obstructive sleep apnoea (OSA) have an increased risk of death from cardiovascular (cv) disease. This study was undertaken to determine the disease spectrum in patients with sonographically proven OSA (apnoea-hypopnoea index > or = 5), with special reference to cv risk factors and accompanying diseases in relation to the severity of their respiratory abnormalities. The study's aim was to clarify what risk factors and accompanying diseases were associated with different degrees of OSA.

PATIENTS AND METHODS

A systematic recording of cv risk factors and accompanying diseases as well as their association to the severity of nocturnal respiratory disorders was made for 175 patients (165 men, 10 women, mean age 54 +/- 10.2 years) with sonographically proven OSA (mean apnoea-hypopnoea index 37 +/- 24.4).

RESULTS

The body mass index (BMI) was significantly related to the severity of the respiratory disorder (apnoea-hypopnoea index, AHI, P < 0.05, odds ratio [OR]: 1.95; 95% confidence interval [CI]: 1.15-3.31). In a multivariate analysis, nocturnal breathing pause (P < 0.05; OR: 3.8; 95% CI: 1.3-11.1), left ventricular hypertrophy (P < 0.01; OR: 3.9; 95% CI: 1.5-10.3) and diabetes mellitus (P < 0.05; OR: 4.2, 95% CI: 1.2-14.7) were independently associated with a high-grade breathing disorder (AHI > or = 20). The incidence of left ventricular hypertrophy rose with an increasing severity of nocturnal OSA.

CONCLUSION

These data indicate that in patients with high-grade OSA (AHI > or = 20) there is a further grouping together of cardiovascular risk factors, namely increasing body weight, diabetes mellitus, arterial hypertension and left ventricular hypertrophy; they explain the increased mortality rate among these patients from vascular complications.

Assessment of municipal solid waste from households in Khulna city of Bangladesh

Waste management is a major concern for both developed and developing countries, with a particular focus on household waste because it makes up a significant proportion of municipal waste. The aim of this study is to assess the state of solid waste management practice in Khulna, as well as to characterize and quantify municipal solid waste as a step toward effective management. To collect information on the existing waste management methods, structured questionnaires were used to conduct surveys of household residents. In this study, whole wards (31 wards) of Khulna City Corporation (KCC) were clustered in 9 groups and selected one ward from each group. To analyze household waste, 75 households from each ward were selected and collected waste for 7 days. The selected household was categorized into five different socioeconomic strata such as low-income, lower-middle-income, middle-income, higher-middle-income and higher-income families. Besides, the assessment was carried out on the production and characterization of household waste that was produced in KCC. The waste samples were quantified, separated and characterized in the laboratory. Results reveal that biodegradable waste is the most prominent type and its percentage is about 81 %. The amount of waste production is positively correlated with income level. The waste generation rate of households for high-income families was 0.652 kg/cap/day while this rate got almost half for a low-income family and its value is o.312 kg/cap/day. Source separation of waste plays a vital role to reduce plastic leakage to the SDP. The result shows the proportion of plastic in mixed waste and source-separated waste after sorting by the waste collector was 4.04 % and 2.99 %, respectively. Survey results show that 42.96 % of respondents think that the source-separated waste should be collected during the period of 12pm to 02pm. A proposed management process was developed for household waste based on the output of this study.