Influence of membrane oxygenators on the pulsatile flow in extracorporeal circuits: an experimental analysis

An experimental analysis was carried out to evaluate the effects induced by two typical extracorporeal circuits on the pressure and flow generated by a roller pump with a pulsatile module. The hydraulic behaviour of the patient was simulated by means of a mechanical mock-up system consisting of a few lumped parameters reproducing the physiologic vascular impedance. Pressure and flow tracings were acquired at different locations along the circuit using an automatic data acquisition system. Nine lest conditions with different pulse frequency and systolic time values were examined using a mean volumetric flow rate of approximately 4 l/min. A complete analysis of the results obtained in terms of pressure drops and inflow-outflow differences across the components of the arterial line, as well as the calculation of the hydraulic pulsatile power along the circuit, allowed us to assess the influence of the various components upon the pulsatility. The results indicated that the membrane oxygenators tested slightly affect the pulsatility of the flow and the pressure; on the contrary the arterial pipe line is responsible for large damping and head losses. To optimize the use of pulsatile flow for cardiopulmonary bypass it is necessary to reduce the length of the arterial pipe lines thus integrating the circuit as much as possible.     

Osteopenic bone cell response to strontium-substituted hydroxyapatite

Ionic substitution is a powerful tool to improve the biological performance of calcium phosphate based materials. In this work, we investigated the response of primary cultures of rat osteoblasts derived from osteopenic (O-OB) bone to strontium substituted hydroxyapatite (SrHA), and to hydroxyapatite (HA) as reference material, compared to normal (N-OB) bone cells. Strontium (Sr) and calcium (Ca) cumulative releases in physiological solution are in agreement with the greater solubility of SrHA than HA, whereas the differences between the two materials are levelled off in DMEM, which significantly reduced ion release. O-OB cells grown on SrHA exhibited higher proliferation and increased values of the differentiation parameters. In particular, Sr substitution increased the levels of proliferation, alkaline phosphatase, and collagen type I, and down-regulated the production of interleukin-6 of O-OB cells, demonstrating a promising future of SrHA in the treatment of bone lesions and defects in the presence of osteoporotic bone.     

Characterization and optimization of Yb-doped photonic-crystal fiber rod amplifiers using spatially resolved spectral interferometry

Spatially resolved spectral interferometry is used to measure the mode content of a Yb-doped photonic-crystal fiber rod amplifier with a 2300 μm(2) mode area. The technique, known as S(2) imaging, was adapted for the short fiber amplifier at full power and revealed a small amount of a copolarized LP(11) mode. Simulations illustrate the potential for weak mode suppression in this fiber and agree qualitatively with the measurements of S(2) and M(2). Higher-order-mode content depends on the alignment of the input signal at injection and ranged from -18 dB for optimized alignment to -13 dB when the injection alignment was offset along the LP(11) axis by 30% of the 55 μm mode-field diameter.     

Osteoporosis Preclinical Research: A Systematic Review on Comparative Studies Using Ovariectomized Sheep

Sheep ovariectomy (OVX) alone or associated to steroid therapy, deficient diet, or hypothalamic–pituitary disconnection has proven to be of critical importance for osteoporosis research in orthopedics. However, the impact of specific variables, such as breed, age, diet, time after OVX, and other variables, should be monitored. Thus, the design of comparative studies is mandatory to minimize the impact of these variables or to recognize the presence of unwanted variables as well as to better characterize bone remodeling in this model. Herein, we conducted a systematic review of the last 10 years on PubMed, Scopus, and Web of Knowledge considering only studies on OVX sheep where a control group was present. Of the 123 records screened, 18 studies were included and analyzed. Results showed that (i) Merino sheep are the most exploited breed; (ii) 5–6 years of age is the most used time for inducing OVX; (iii) ventral midline laparotomy is the most common approach to induce OVX; (iv) OVX associated to steroid therapy is the most widely used osteoporosis model; and (v) success of OVX was mostly verified 12 months after surgery. In detail, starting from 12 months after OVX a significant decline in bone mineral density and in microarchitectural bone parameters as well as in biochemical markers were detected in all studies in comparison to control groups. Bone alteration was also site-specific on a pattern as follows: lumbar vertebra, femoral neck, and ribs. Before 12 months from OVX and starting from 3–5 months, microarchitectural bone changes and biochemical marker alterations were present when osteoporosis was induced by OVX associated to steroid therapy. In conclusion, OVX in sheep influence bone metabolism causing pronounced systemic bone loss and structural deterioration comparable to the situation found in osteoporosis patients. Data for treating osteoporosis patients are based not only on good planning and study design but also on a correct animal use that, as suggested by 3Rs principles and by ARRIVE guidelines, includes the use of control groups to be directly contrasted with the experimental group.     

Effects of synthetic salmon calcitonin and alendronate on bone quality in ovariectomized rats

BACKGROUND: The aim of this study was to assess the effect of calcitonin (CCT) and alendronate (ALN) on bone quality through histomorphometric, histological, densitometric and crystallographic evaluations in an experimental model of osteoporosis obtained in ovariectomized rats. METHODS: The animals were randomly assigned to the treatment with CCT (2 IU/kg/day, N-12) or with ALN (6 micrograms/kg/day, N-12) given subcutaneously, starting three months after ovariectomy: treatment lasted 60 days. Six rats untreated after ovariectomy and other 6 non ovariectomized (intact) were taken as controls. At the end of treatment the animals were sacrificed and femurs explanted for laboratory examinations. Results were evaluated by an ANOVA followed by the Tukey's test when appropriate. RESULTS: The histomorphometric analysis showed a significant increase of the trabecular bone volume and of the cortical bone thickness either with CCT and ALN in comparison with the ovariectomized untreated controls. Optic and electronic microscopy examinations suggest a higher bone remodeling after ALN than after CCT, but accompanied by areas of imperfect mineralization, and more irregular osteon and collagen fibres disposition. The densitometry carried out at the femoral head and diaphysis showed a similar bone mass increase following either CCT and ALN, but significantly higher in comparison to the untreated controls. At the diaphysis level ALN was superior in increasing the bone mass also when compared to the intact rats. The mineralogic exams showed that CCT acted on the re-elaboration of the mineral phase approaching the molar ratio Ca/PO4 to the physiological values typical of senescence, and crystallography revealed that the formation of hydroxyapatite crystals follows a physiological mineral redeposition: those phenomena were not observed for ALN. CONCLUSIONS: In conclusion both CCT and ALN could reduce the bone loss due to osteoporosis, by increasing the bone mass and thickness. Nevertheless the submicroscopic and chemical bone structure are less similar to the physiologic ones after treatment with ALN.     

Comparison between the <Emphasis Type="Italic">in vitro</Emphasis> surface transformations of AP40 and RKKP bioactive glasses

Two bioactive silica-phosphate glasses, AP40 and RKKP, were compared in their behaviour in simulated biological environment. Their chemical composition is practically identical, except that RKKP contains small amounts of amphoteric network-former oxides Ta₂O₅ and La₂O₃ (composition in wt% for AP40: -Ca₃(PO₄)₂24.50, SiO₂44.30, CaO 18.60, Na₂O 4.60, K₂O 0.19, MgO 2.82, CaF₂ 4.99; RKKP: -Ca₃(PO₄)₂24.23, SiO₂ 43.82, CaO 18.40, Na₂O 4.55, K₂O 0.19, MgO 2.79, CaF₂ 4.94, Ta₂O₅ 0.99, La₂O₃ 0.09).Previous investigations showed a better performance in osteopenic bone for RKKP. To gain more insight into these differences in biological behaviour, the in vitro bioactivity of the glasses was studied by treatment with a continuously replenished Hanks Balanced Salt Solution (HBSS).The glasses were examined before and after HBSS treatment for 20 and 40 days by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), X-ray Energy Dispersion (EDX), Raman and IR vibrational spectroscopies.Some slight but notable differences between the two glasses were observed after HBSS treatment. IR and EDX analyses showed that deposits formed on both glasses were composed of a calcium deficient carbonate-apatite; however, the layer formed on RKKP glass was found to be slightly more calcium deficient and thinner. EDX analysis evidenced the presence of a small percentage of F^– ions only in the layers formed on the RKKP samples.The differences disclosed, although slight, can contribute to the understanding of the different biological behaviour previously observed.     

Schizophrenia in high-risk subjects: Prognostic maternal characteristics.

A Danish prospective, longitudinal study of 207 children (average age 15 yrs) at high risk for schizophrenia (they have schizophrenic mothers), begun in 1962, involved assessment of mothers on a number of variables. In 1972 it was found that 17 of the children of these mothers became schizophrenic. The present study sought to identify predictors of schizophrenia among antecedent maternal variables. The mothers (15 Ss) of the children who became schizophrenic (a) had psychosis precipitated by childbirth and (b) exhibited instability in their relations with men as well as antisocial behaviors. (9 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sensitivity of direct metal laser sintering Maraging steel fatigue strength to build orientation and allowance for machining

This work deals with the effect of build orientation and of allowance for machining on DMLS‐produced Maraging Steel MS1. The experimental results, arranged by tools of Design of Experiment, have been statistically processed and compared. The outcomes were that, probably due to effect of the thermal treatment, machining, and material properties, the aforementioned factors do not have a significant impact on the fatigue response. This made it possible to work out a global curve that accounts for all the results, consisting in a high amount of data points. This can be regarded as one of the most complete and reliable fatigue models in the current literature. Fractographic and micrographic studies have been performed as well, to individuate the crack initiation points, usually located at subsurface porosities, and to investigate the location of internal inclusions and the actual martensitic microstructure along the stacking direction and on the build plane.     

Design and Evaluation In Vitro of Controlled Release Mucoadhesive Tablets Containing Chlorhexidine

ABSTRACT

This investigation deals with the development of buccal tablets containing chlorhexidine (CHX), a bis-bis-guanide with antimicrobial and antiseptic effects in the oral cavity, and able to adhere to the buccal mucosa to give local controlled release of drug. A mucoadhesive formulation was designed to swell and form a gel adhering to the mucosa and controlling the drug release into the oral cavity.

Some batches of tablets were developed by direct compression, containing different amounts of hydroxypropylmethylcellulose (HPMC) and carbomer; changing the amount ratio of these excipients in formulations, it is possible easily modulate the mucoadhesive effect and release of drug. The in vitro tests were performed using the USP 26/NF paddle apparatus, a specifically developed apparatus, and a modified Franz diffusion cells apparatus. This last method allows a simultaneous study of drug release rate from the tablets and drug permeation through the buccal mucosa.

Similar tests have also been carried out on a commercial product, Corsodyl gel^®, in order to compare the drug release control of gel with respect to that of the mucoadhesive tablet, as a formulation for buccal delivery of CHX. While the commercial formulation does not appear to control the release, the formulation containing 15% w/w methocel behaves the best, ensuring the most rapid and complete release of the drug, together with a negligible absorption of the active agent as required for a local antiseptic action in the oral cavity.     

The latent structure of schizotypy: I. Premorbid indicators of a taxon of individuals at risk for schizophrenia-spectrum disorders.

A taxometric analysis (R. R. Golden & P. E. Meehl, 1979) was conducted to test the hypotheses that liability for schizophrenia-spectrum disorders is dichotomously distributed and that this liability can be detected premorbidly with behavioral indicators analogous to many of the criteria for schizotypal personality disorder. Behaviors were assessed in 207 offspring of schizophrenic mothers and 104 matched offspring of normal parents in 1962, when participants' mean age was 15 years. Diagnoses on the basis of the Diagnostic and Statistical Manual of Mental Disorders (3rd ed., rev.; American Psychiatric Association, 1987) were made in 1986–1989, when participants were nearly through the risk period for developing schizophrenia. The aggregation of indicators was consistent with a bimodal latent liability distribution. Membership in the schizotypal class was a sensitive and specific predictor of the emergence of schizophrenia-spectrum disorders in adulthood. (PsycINFO Database Record (c) 2010 APA, all rights reserved)