Increased exposure to loading is associated with decreased plantar soft tissue hardness in people with diabetes and neuropathy.

AIMS: Literature indicates that altered plantar loading in people with diabetes could trigger changes in plantar soft tissue biomechanics which, in turn, could affect the risk for ulceration. To stimulate more research in this area, this study uses in vivo testing to investigate the link between plantar loading and tissue hardness. METHODS: Tissue hardness and plantar pressure distribution were measured for six plantar areas in 39 people with diabetes and peripheral neuropathy. RESULTS: Spearman correlation analysis revealed that increased pressure time integral at the 1st metatarsal-head region (r = -0.354, n = 39, P = 0.027) or at the heel (r = -0.378, n = 39, P = 0.018) was associated with reduced hardness in the same regions. After accounting for confounding parameters, generalised estimating equations analysis also showed that 10% increase in pressure time integral at the heel was associated with ≈ 1 unit reduction in hardness in the same region. CONCLUSIONS: For the first time, this study reveals that people with diabetes and neuropathy who tend to load their feet more heavily also tend to have plantar soft tissues with lower hardness. The observed difference in tissue hardness is likely to affect the tissue's vulnerability to overload injury. More research will be needed to explore the implications of the observed association for the risk of ulceration.

Understanding the role of iron in the magnetism of Fe doped ZnO nanoparticles.

The actual role of transition metals like iron in the room temperature ferromagnetism (RTFM) of Fe doped ZnO nanoparticles is still an unsolved problem. While some studies concluded that the Fe ions participate in the magnetic interaction, others in contrast do not believe Fe to play a direct role in the magnetic exchange interaction. To contribute to the understanding of this issue, we have carefully investigated the structural, optical, vibrational and magnetic properties of sol-gel synthesized Zn1-xFexO (0 < x < 0.10) nanoparticles. No Fe(2+) was detected in any sample. We found that high spin Fe(3+) ions are substitutionally incorporated at the Zn(2+) in the tetrahedral-core sites and in pseudo-octahedral surface sites in ZnO. Superficial OH(-) was observed in all samples. For x ≤ 0.03, an increment in Fe doping concentration decreased a and c lattice parameters, average Zn-O bond length, average crystallite size and band gap; while it increased the degree of distortion and quadrupole splitting. Undoped ZnO nanoparticles exhibited very weak RTFM with a saturation magnetization (Ms) of ∼0.47 memu g(-1) and this value increased to ∼2.1 memu g(-1) for Zn0.99Fe0.01O. Very interestingly, the Ms for Zn0.99Fe0.01O and Zn0.97Fe0.03O increased by a factor of about ∼2.3 by increasing annealing for 1 h to 3 h. For x ≥ 0.05, ferrimagnetic disordered spinel ZnFe2O4 was formed and this phase was found to become more ordered with increasing annealing time. Fe does not contribute directly to the RTFM, but its presence promoted the formation of additional single charged oxygen vacancies, zinc vacancies, and more oxygen-ended polar terminations at the nanoparticle surface. These defects, which are mainly superficial, altered the electronic structure and are considered as the main sources of the observed ferromagnetism.

Ferromagnetism in annealed Ce0.95Co0.05O2 and Ce0.95Ni0.05O2 nanoparticles.

This paper reports an investigation on the role of transition-metal ions in producing ferromagnetism in CeO2 nanoparticles by electron paramagnetic resonance (EPR). Several samples of CeO2 nanoparticles annealed at 200, 300, 400, and 500 degrees C, doped with 5% Ni and 5% Co ions, characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetry analysis (TGA) and mass spectroscopy (MS), were investigated by X-band EPR at 4, 10 and 300 K, and by magnetometry at 300 K. Magnetic properties and EPR/FMR (Ferromagnetic Resonance) spectra of these nanoparticle samples were found to depend strongly on the annealing temperature (T(A)), oxygen stoichiometry, and dopant-ion species. Different behavior of saturation magnetization in the samples with the dopants, Co and Ni, is found to be due to different-inward and outward-surface diffusion of these impurity ions, respectively, during annealing. A detailed simulation of EPR/FMR spectra of isolated Co and Ni ions carried out here provides in-depth details on the role of the doped ions and oxygen (O-) defects played in the observed magnetic properties.

A 236-GHz Fe EPR STUDY OF NANO-PARTICLES OF THE FERRO-MAGNETIC ROOM-TEMPERATURE SEMICONDUCTOR Sn(1-x)Fe(x)O(2)(x=0.005).

High frequency (236 GHz) electron paramagnetic resonance (EPR) studies of Fe(3+) ions at 255 K are reported in a Sn(1-x)Fe(x)O(2) powder with x = 0.005 which is a ferromagnetic semiconductor at room temperature. The observed EPR spectrum can be simulated reasonably well as overlap of spectra due to four magnetically inequivalent high-spin (HS) Fe(3+) ions (S = 5/2). The spectrum intensity is calculated, using the overlap I(BL) + (I(HS1)+I(HS2)+I(HS3)+I(HS4))×e(-0.00001×B), where B is the magnetic field intensity in Gauss, I represents the intensity of an EPR line (HS1, HS2, HS3, HS4), and BL stands for the base line. (The exponential factor, as found by fitting to the experimental spectrum, is related to the Boltzmann population distribution of energy levels at 255 K, which is the temperature of the sample in the spectrometer.) These high-frequency EPR results are significantly different from those at X-band. The large values of the zero-field splitting parameter (D) observed here for the four centers at the high frequency of 236 GHz are beyond the capability of X-band, which can only record spectra of ions only with much smaller D values than those reported here.

Effect of Co doping on the structural, optical and magnetic properties of ZnO nanoparticles.

We report the results of a detailed investigation of sol-gel-synthesized nanoscale Zn(1-x)Co(x)O powders processed at 350 °C with 0≤x≤0.12 to understand how the structural, morphological, optical and magnetic properties of ZnO are modified by Co doping, in addition to searching for the theoretically predicted ferromagnetism. With x increasing to 0.03, both lattice parameters a and c of the hexagonal ZnO decreased, suggesting substitutional doping of Co at the tetrahedral Zn(2+) sites. For x>0.03, these trends reversed and the lattice showed a gradual expansion as x approached 0.12, probably due to additional interstitial incorporation of Co. Raman spectroscopy measurements showed a rapid change in the ZnO peak positions for x>0.03, suggesting significant disorder and changes in the ZnO structure, in support of additional interstitial Co doping possibility. Combined x-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance spectroscopy, photoluminescence spectroscopy and diffuse reflectance spectroscopy showed clear evidence for tetrahedrally coordinated high-spin Co(2+) ions occupying the lattice sites of ZnO host system, which became saturated for x>0.03. Magnetic measurements showed a paramagnetic behaviour in Zn(1-x)Co(x)O with increasing antiferromagnetic interactions as x increased to 0.10. Surprisingly, a weak ferromagnetic behaviour was observed for the sample with x = 0.12 with a characteristic hysteresis loop showing a coercivity H(c)∼350 Oe, 25% remanence M(r), a low saturation magnetization M(s)∼0.04 emu g(-1) and with a Curie temperature T(c)∼540 K. The XPS data collected from Zn(1-x)Co(x)O samples showed a gradual increase in the oxygen concentration, changing the oxygen-deficient undoped ZnO to an excess oxygen state for x = 0.12. This indicates that such high Co concentrations and appropriate oxygen stoichiometry may be needed to achieve adequate ferromagnetic exchange coupling between the incorporated Co(2+) ions.

Carrier-controlled ferromagnetism in transparent oxide semiconductors.

The search for an ideal magnetic semiconductor with tunable ferromagnetic behaviour over a wide range of doping or by electrical gating is being actively pursued as a major step towards realizing spin electronics. A magnetic semiconductor having a high Curie temperature, capable of independently controlled carrier density and magnetic doping, is crucial for developing spin-based multifunctional devices. Cr-doped In(2)O(3) is such a unique system, where the electrical and magnetic behaviour-from ferromagnetic metal-like to ferromagnetic semiconducting to paramagnetic insulator-can be controllably tuned by the defect concentration. An explicit dependence of magnetic interaction leading to ferromagnetism on the carrier density is shown. A carrier-density-dependent high Curie temperature of 850-930 K has been measured, in addition to the observation of clear magnetic domain structures in these films. Being optically transparent with the above optimal properties, Cr-doped In(2)O(3) emerges as a viable candidate for the development of spin electronics.

mu-Opioid receptors often colocalize with the substance P receptor (NK1) in the trigeminal dorsal horn.

Substance P (SP) is a peptide that is present in unmyelinated primary afferents to the dorsal horn and is released in response to painful or noxious stimuli. Opiates active at the mu-opiate receptor (MOR) produce antinociception, in part, through modulation of responses to SP. MOR ligands may either inhibit the release of SP or reduce the excitatory responses of second-order neurons to SP. We examined potential functional sites for interactions between SP and MOR with dual electron microscopic immmunocytochemical localization of the SP receptor (NK1) and MOR in rat trigeminal dorsal horn. We also examined the relationship between SP-containing profiles and NK1-bearing profiles. We found that 56% of SP-immunoreactive terminals contact NK1 dendrites, whereas 34% of NK1-immunoreactive dendrites receive SP afferents. This result indicates that there is not a significant mismatch between sites of SP release and available NK1 receptors, although receptive neurons may contain receptors at sites distant from the peptide release site. With regard to opioid receptors, we found that many MOR-immunoreactive dendrites also contain NK1 (32%), whereas a smaller proportion of NK1-immunoreactive dendrites contain MOR (17%). Few NK1 dendrites (2%) were contacted by MOR-immunoreactive afferents. These results provide the first direct evidence that MORs are on the same neurons as NK1 receptors, suggesting that MOR ligands directly modulate SP-induced nociceptive responses primarily at postsynaptic sites, rather than through inhibition of SP release from primary afferents. This colocalization of NK1 and MORs has significant implications for the development of pain therapies targeted at these nociceptive neurons.

Median sternotomy single stage complete unifocalization for pulmonary atresia, major aorto-pulmonary collateral arteries and VSD-early experience.

OBJECTIVE: It is a prospective study to assess the results of median sternotomy, single stage complete unifocalization and repair for ventricular septal defect (VSD), pulmonary atresia and major aorto pulmonary collateral arteries (MAPCAs). METHODS: From June 97 to August 98, 20 patients were treated with single stage complete unifocalization and repair. Their ages ranged from 6 months to 11 years. Through median sternotomy, all MAPCAs were dissected and looped. On cardiopulmonary bypass, MAPCAs were anastomosed to native pulmonary arteries (PAs) or to MAPCAs. VSD was closed if possible and RV to PA continuity was established with a homograft conduit. If complete repair was not suitable, central shunt was done from ascending aorta to reconstructed PA with a polytetrafluroethylene graft. The patients were divided into three groups according to the arborization pattern in the lungs. Group 1 had well formed native PAs with MAPCAs, group 2 had hypoplastic PAs with MAPCAs and group 3 had only MAPCAs. RESULTS: Twenty patients had 21 procedures. All MAPCAs were unifocalized with tissue-to-tissue anastomosis for future growth, except one in whom polytetrafluroethylene tube graft was used to attain the confluence. In group 1, all seven patients had complete unifocalization and repair. In group 2, four patients had RV to PA conduit and two patients had central shunt. In group 3, three patients had complete repair, three patients had RV to PA conduit and one patient had central shunt. There were three deaths, two in group 2 and one in group 3. The first patient died due to a wrong decision to close the VSD, the second patient died due to missed large MAPCA in preoperative angio and the third patient was a 7-year-old boy who died with irreversible pulmonary vascular changes due to unprotected MAPCAs. CONCLUSIONS: To conclude, complete repair/RV-PA conduit/central shunt should be done according to the size of the total pulmonary vasculature in patients with group 1, 2 and 3 with protected PAs/MAPCAs and in hypoplastic or absent PAs with unprotected MAPCAs (less than 1 year) and protected MAPCAs. We are yet to determine the surgical procedure to be performed in hypoplastic/absent PAs with unprotected MAPCAs more than 1 year. It is very essential to delineate all the MAPCAs up to the level of the diaphragm preoperatively.

Novel techniques of bidirectional Glenn shunt without cardiopulmonary bypass.

BACKGROUND: We report novel techniques of performing bidirectional Glenn shunt (BDG) without cardiopulmonary bypass (CPB). METHODS: Five cases of single ventricle and pulmonary stenosis (PS) complex were taken up for BDG without CPB. The criteria for case selection were an unrestrictive atrial septal defect (ASD), no atrioventricular (AV) valve regurgitation, and no other intracardiac defects requiring correction. A temporary shunt was established between the superior vena cava (SVC) and contralateral branch pulmonary artery (PA) for venous drainage during SVC clamping for BDG anastomosis in four cases. In case 5, a shunt was put between the SVC and right atrium (RA) for venous drainage, and modified Blalock Taussig shunt and patent ductus arteriosus (PDA) were left open until the completion of the BDG. RESULTS: Central venous pressure (CVP) increased to a mean of 22.4 mm Hg during SVC clamping, with improvement of oxygen (O2) saturation from 62.4% to 82.4%. After Glenn shunt, CVP and O2 saturation maintained at 13.2 mm Hg and 87.4%, respectively. Postoperatively, there were no neurological abnormalities and no hospital mortality. CONCLUSIONS: Our technique provides an excellent venous drainage with improvement of O2 saturation during SVC clamping. It avoids problems related to CPB and economy. It is easily reproducible, with excellent results in a selected group of patients without compromising the completeness of repair.

Inhaled nitric oxide as therapy for pulmonary hypertension in postoperative cases of congenital heart defects.

This is a prospective study using inhaled nitric oxide (NO) as a selective pulmonary vasodilator in postoperative cases of CHD. From February 1995 to December 1995, NO was used selectively in 10 patients postoperatively in whom conventional management of PAH crisis failed and PA pressures were more than half the systemic pressure. The age of the patients varied from 2 months to 3 years and duration of NO inhalation ranged from 1 day to 13 days. Of 10 patients, 8 patients responded well with 5-20 ppm and 2 did not respond, even after increasing the NO to 120 ppm. The preoperative mean pulmonary systolic pressure was 83 +/- 17.1 mm Hg against mean systemic systolic pressure of 84 +/- 9.2 mm Hg. Postoperatively, their PA pressure reduced to 54 +/- 16.1 mm Hg (mean systolic) with systemic pressure of 85 +/- 15.9 mm Hg (mean systolic). After using inhaled NO, PA pressure dropped to 19 +/- 2.5 mm Hg mean systolic (p < 0.0078), after excluding the nonresponders. The two nonresponders died postoperatively. Our study shows that NO selectively reduces the PA pressure unlike conventional vasodilators. This helps to decrease the incidence of postoperative PAH crisis, thereby reducing the morbidity and mortality. However, long-term beneficial effects are yet to be studied.