Fabrication and in vivo evaluation of hydroxyapatite/carbon nanotube electrospun fibers for biomedical/dental application.

The aim was to synthesize bioactive electrospun fibers for biomedical and dental application with improved biocompatibility. In situ precipitation of nano-hydroxyapatite (nHA) was performed with various concentrations (0.5%, 1%, 2%, 3%, and 5% wt/wt) of functionalized multi-walled-carbon nanotubes (MWCNTs) by using microwave irradiation technique. The obtained composites were characterized by Fourier Transform Infrared (FTIR), X-ray Diffraction (XRD), Thermogravimetric Analysis/Differential Scanning Calorimetry (TGA/DSC), and the cylindrical discs were made for mechanical testing. The failure behavior was analyzed by Scanning Electron Microscope (SEM). CNT and HA/CNT were silanized with γ-methacryloxypropyl-trimethoxysilane (MPTS) and mixed with polyvinyl alcohol (10% wt./vol.) and electrospun to fabricate fibers. The biocompatibility of both fibers was accessed by their effects on angiogenesis in a chick chorioallantoic membrane (CAM) assay. The electrospun fibers were analyzed by SEM. FTIR confirmed the structural behavior of pre and post-silanized HA/CNT. XRD showed the phase purity and crystallinity before and after heat treatment. Mechanical properties showed that 3% loaded HA/CNT has higher compressive strength (100.5±5.9MPa) compared to others and the failure behavior exhibited dispersion of CNT in HA matrix. The HA/CNT electrospun fibers showed significantly more blood vessels formation compared to CNT fibers. These HA/CNT electrospun fibers showed promising results in terms of biocompatibility and with improved mechanical properties of CNT reinforced composites, they can be used in load bearing clinical applications.

Sociodemographic characteristics and sexual behavior as risk factors for human papillomavirus infection in Saudi Arabia.

OBJECTIVES: To determine the prevalence and the sociodemographic characteristics and sexual behavior risk factors for human papillomavirus (HPV) infection in a hospital-based cohort of women in Saudi Arabia. METHODS: Cervical specimens and questionnaire data were collected from women attending clinics in Riyadh, Saudi Arabia. Cervical specimens were examined for abnormal cytology using a standard Pap test and for the presence of HPV-DNA using PCR and reverse line blot hybridization tests. RESULTS: Approximately 73% of the 400 women tested were Saudi nationals. Nearly 50% were under 40 years old (range 22-80 years, mean±standard deviation 41.20±10.43 years). Approximately 17% of the women were HPV-positive. The most commonly detected HPV types were HPV-18 (34%) and HPV-16 (19%), with multiple infections detected in 10% of positive specimens. Multivariate analyses revealed that smoking and multiple partners were significant risk factors for HPV infection (p<0.01). CONCLUSIONS: Because of societal challenges and an unsubstantiated assumption of low HPV prevalence, few studies have examined sociodemographic characteristics or sexual behaviors associated with HPV in Saudi women. However, a high prevalence of HPV infection was found, with smoking and multiple partners as significant risk factors, in this hospital-based cohort of predominantly Saudi women.

Systematic viewing in radiology: seeing more, missing less?

To prevent radiologists from overlooking lesions, radiology textbooks recommend "systematic viewing," a technique whereby anatomical areas are inspected in a fixed order. This would ensure complete inspection (full coverage) of the image and, in turn, improve diagnostic performance. To test this assumption, two experiments were performed. Both experiments investigated the relationship between systematic viewing, coverage, and diagnostic performance. Additionally, the first investigated whether systematic viewing increases with expertise; the second investigated whether novices benefit from full-coverage or systematic viewing training. In Experiment 1, 11 students, ten residents, and nine radiologists inspected five chest radiographs. Experiment 2 had 75 students undergo a training in either systematic, full-coverage (without being systematic) or non-systematic viewing. Eye movements and diagnostic performance were measured throughout both experiments. In Experiment 1, no significant correlations were found between systematic viewing and coverage, r = -.10, p = .62, and coverage and performance, r = -.06, p = .74. Experts were significantly more systematic than students F2,25 = 4.35, p = .02. In Experiment 2, significant correlations were found between systematic viewing and coverage, r = -.35, p < .01, but not between coverage and performance, r = .13, p = .31. Participants in the full-coverage training performed worse compared with both other groups, which did not differ between them, F2,71 = 3.95, p = .02. In conclusion, the data question the assumption that systematic viewing leads to increased coverage, and, consequently, to improved performance. Experts inspected cases more systematically, but students did not benefit from systematic viewing training.

Photochemical alterations of natural and anthropogenic dissolved organic nitrogen in the York River.

In the following study, we addressed the effects of photoirradiation on the turnover of dissolved organic nitrogen (DON) from both natural and anthropogenic sources at the molecular level. Analysis of long-term photoirradiated samples via Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) identified both the photolabile and the photoproduced DON from both natural and anthropogenic sources. Although photoproduction of DON was prominent with natural dissolved organic matter (DOM) sources, even in a low nitrogen environment, the anthropogenic source shows a shift from photobleaching to photohumification denoted by an increase in the average molecular weight (MW) and the double bound equivalent (DBE) after 25 days of a continuous exposure to UV light, implying condensation of low MW molecules (LMW) to form high MW (HMW) molecules. Furthermore, the sharp increase in N/C molar ratio, in the anthropogenic source, substantiates the photoinduced dissolved inorganic nitrogen (DIN) incorporation hypothesis. Hence, our findings suggest that anthropogenic input will drive substantial variation in riverine DOM and, thus, estuarine optics and photochemistry and bioavailability. Furthermore, we validate that photochemistry is one of the main processes that shapes the DON quality in aquatic systems regardless of its original source.

Two dimensional correlation analysis of Fourier transform ion cyclotron resonance mass spectra of dissolved organic matter: a new graphical analysis of trends.

Two-dimensional (2D) correlation analysis was applied to 20 Fourier transform ion cyclotron resonance mass spectra (FTICR-MS) of ultrafiltered dissolved organic matter samples from a salinity transect of the lower Chesapeake Bay. We were able to investigate the chemical changes in the dissolved organic matter pool at the molecular level and classify the individual peaks based on their biogeochemical reactivity. The power of this technique is its ability to be used on either the presence/absence of the individual peaks or their normalized magnitudes. The presence or absence of the peaks are utilized to identify the reactivity and correlation between peaks that plot in different regions of the van Krevelen diagram, whereas the normalized magnitudes are used to correlate the changes among individual peaks. One of the promising advantages of 2D correlation of FTICR-MS data is the ability to associate the variations of the individual peaks with the changes in the functional groups that are measured by other spectroscopic techniques. This approach takes us one step further from identifying molecular formulas to proposing chemical structures.

Using two-dimensional correlations of ¹³C NMR and FTIR to investigate changes in the chemical composition of dissolved organic matter along an estuarine transect.

Applying two-dimensional correlation spectroscopy to (13)C NMR and FTIR spectra of the high molecular-weight dissolved organic matter (HMW-DOM) isolated along an Elizabeth River/Chesapeake Bay salinity transect shows that HMW-DOM consists of three major components that have different biogeochemical reactivities. The first appears to be a heteropolysaccharide (HPS) component and its contribution to carbon increases as we approach the marine offshore. The second appears to be composed of carboxyl-rich compounds (CRC); its carbon percentage decreases. The third component contains the major functional group of amide/amino sugar (AMS) and its carbon percentage stays almost constant along the salinity transect. It seems that the HPS and CRC are present in many aquatic environments at different relative ratios. The 2D-correlation maps reveal that each of these components is composed of dynamic mixtures of compounds that share similar backbone structures but have significant functional group differences. Two-dimensional (2D) correlation spectroscopy is a powerful new biogeochemical tool to track the changes in complex organic matter as a function of space, time, or environmental effects.

Purification and properties of lactate dehydrogenase from liver of Uromastix hardwickii.

Lactate dehydrogenase isoenzyme-1 was purified from liver of Uromastix hardwickii using colchicine-Sepharose and heat-inactivation methods. The crude enzyme showed four isoenzymes by agarose gel electrophoresis (AGE). The purified enzyme showed a single band after native AGE and SDS-PAGE corresponding to a molecular weight of 34 kDa. The enzyme did not bind with DEAE-Sepharose at pH 7.2. The optimum pH for forward reaction was 7.5, while for reverse reaction, the maximum activity was at pH 9.5. The Km values for pyruvate, NADH, lactate and NAD+ were 0.105, 0.045, 9.0 and 0.011 mM, respectively. The pyruvate showed maximum activity at about 150 microM and then starts showing inhibition at higher concentration. Pre-heating of enzyme showed that it was stable at 80 degrees C for 30 min and at 100 degrees C it became inactive immediately. Oxalate, glutamate, Cu2+, Co2+, Mn2+, and Mg2+ have shown inhibitory effects both for forward- and reverse-reactions. From these properties, we suggest that LDH-1 from Uromastix liver may be quite different from that of other vertebrates.

Estimation and separation of N-acetyl-beta-D-glucosaminidase isoenzymes in urine.

N-acetyl-beta-D-glucosaminidase is a lysosomal enzyme made up of two isoenzymes (A and B). It has been used extensively as a marker for kidney damage. However, its estimation in urine has not been standardized. We have established a method for the estimation and separation of NAG isoenzymes by ion-exchange chromatography. In 19 experiments done so far, this method has given reproducible results. The significance of this method is that with a single experiment, one can estimate total as well as individual isoenzyme activity. Furthermore, urine constituents do not appear to interfere in this assay.

Ileal perforation due to arteriovenous malformation in a premature infant.

Gastrointestinal arteriovenous malformations (AVM) in children are most commonly associated with bleeding. Although not previously reported, we present a case of an AVM associated with intestinal perforation in a premature infant.