Reduction of spectral interferences using ultraclean gold nanowire arrays in the LDI-MS analysis of a model peptide.

The surface chemistry of gold nanowires (AuNWs) has been systematically assessed in terms of contamination and cleaning processes. The nanomaterial's surface quality was correlated to its performance in the matrix-free laser desorption ionization mass spectrometry (LDI-MS) analysis of low molecular weight analytes. Arrays of AuNWs were deposited on glass slides by means of the lithographically patterned nanowire electrodeposition technique. AuNWs were then characterized in terms of surface chemical composition and morphology using X-ray photoelectron spectroscopy, scanning electron microscopy and atomic force microscopy. AuNWs were subjected to a series of well-known cleaning procedures with the aim of producing the best performing surfaces for the LDI-MS detection of leucine enkephalin, chosen as a model analyte with a molar mass below 1,000 g/mol. Prolonged cyclic voltammetry in 2 M sulfuric acid and, most of all, oxygen plasma cleaning for 5 min provided the best results in terms of simpler (interference-free) and more intense mass spectrometry spectra of the reference compound. The analyte always ionized as the sodiated adduct, and leucine enkephalin limits of detection of 0.5 and 2.5 pmol were estimated for the positive and negative analysis modes, respectively. This study points out the tight correlation existing between the chemical status of the nanostructure surface and the AuNW-assisted LDI-MS performance in terms of reproducibility of spectra, intensity of analyte ions and reduction of interferences.

Synthesis and characterization of taper- and rodlike si nanowires on Si(x)Ge(1-x) substrate.

Taper- and rodlike Si nanowires (SiNWs) are synthesized successfully on Si and Si(0.8)Ge(0.2) substrates. The growth mechanisms of taper- and rodlike SiNWs are proposed to be oxide-assisted growth (OAG) and vapor-liquid-solid (VLS) growth, respectively. For taperlike SiNWs annealed at 1200 degrees C for 3 h, the emission peaks are found at 772, 478, and 413 nm. On the other hand, for rodlike SiNWs annealed at 1200 degrees C for 4 h, emission peaks are found at 783, 516, and 413 nm. From the field-emission measurements, the taperlike Si nanowires exhibit superior field-emission behavior with a turn-on field of 6.3-7.3 V/mum. The field enhancement, beta, has been estimated to be 700 and 1000 at low and high fields, respectively. The excellent field-emission characteristics are attributed to the perfect crystalline structure and the taperlike geometry of the Si nanowires.

Simulect induction facilitates Neoral-based steroid-free immunosuppression in primary kidney transplant recipients.

This study compares outcomes of kidney transplantation with two distinct induction protocols Basiliximab (Simulect) versus Muromonab (OTK 3) in the setting of cyclosporine (Neoral)-based immunosuppression. Postinduction protocols included either total prednisone avoidance or prednisone sparing versus standard prednisone dosing. Two hundred forty five adult patients receiving kidney transplantation between 1995 and 2000 were included in the study. Treatment in group 1 was OKT 3 + Neoral + adjunct + standard prednisone; group 2, Simulect + Neoral + adjunct + steroid sparing; group 3, Simulect + Neoral + adjunct + no prednisone. The demographics between all groups were similar. The mean (+/- SD) trough cyclosporine levels at 1 month were 276 +/- 128 versus 291 +/- 180 versus 398 +/- 365 (P=.020); at 3 months were 261 +/- 120 versus 280 +/- 152 versus 399 +/- 408 (P=.32); at 12 month were 235 +/- 144 versus 245 +/- 154 versus 234 +/- 132 (P=.96). Creatinine clearance at 1 month was 59 +/- 24 versus 58 +/- 18 versus 47 +/- 23 mL/min (P=.004); at 3 months was 66 +/- 28 versus 62 +/- 22 versus 53 +/- 25 mL/min (P=.007); at 12 months was 68 +/- 38 versus 65 +/- 22 versus 64 +/- 29 mL/min (P=.556). Serum creatinine at 1 month was 1.8 +/- 0.9 versus 1.6 +/- 1.2 versus 2.8 +/- 2.21 mg/dL (P=.005); at 3 months was 1.7 +/- 0.6 versus 1.9 +/- 1.0 versus 2.3 +/- 1.3 mg/dL (P=.007); at 12 months was 1.9 +/- 1.3 versus 2.1 +/- 1.0 versus 2.3 +/- 1.7 mg/dL (P=.179). The incidence of acute rejection within 1 year in the respective groups were 28% versus 15% versus 16%. Therefore, we conclude that using Simulect in transplant recipients results in long-term patient and graft survival similar to those achieved with OKT 3. The use of Simulect resulted in significant reduction in clinical rejection incidence within the first year regardless of steroid use. Thus, the use of Simulect allows complete steroid avoidance in Neoral-based immunosuppression regimen.

Acid-base balance and nutrition in peritoneal dialysis.

Acidosis has been implicated in increased protein catabolism and malnutrition of dialysis. The present study examines the effect of acid-base balance on the nutrition status of peritoneal dialysis (PD) patients. We followed 43 PD patients for one year. Blood chemistries were measured monthly. Patients were divided on the basis of subjective global assessment (SGA) into well-nourished (A), mildly-to-moderately malnourished (B), and severely malnourished (C) groups. Mean serum bicarbonate and albumin concentrations were, for group A (n = 16), 23.5 mmol/L and 3.96 g/dL respectively; for group B (n = 17), 27.2 mmol/L and 3.50 g/dL respectively; and for group C (n = 10), 25.9 mmol/L and 2.9 g/dL respectively. In group A, mean serum bicarbonate was significantly lower, and albumin concentration significantly higher as compared with the other groups. Interestingly, of 9 patients with serum HCO3 < 22 mmol/L, 6 were in group A and 2 were in group B. Of 6 patients with serum HCO3 > 29 mmol/L, 5 were in group B and 4 were in group C. The data suggest that well-nourished PD patients tend to be more acidotic. Malnutrition in alkalotic PD patients may be due to low protein intake resulting in decreased acid production; however, an effect of alkalosis on protein metabolism cannot be excluded.

Control of preweaning diarrhea in piglets by acupuncture and Chinese medicine.

Preweaning diarrhea in piglets is a very common disease. Even thought vaccination and antibiotics are used widely for controlling the disease nowadays, it is still a serious production problem. Therefore, the search for a new medication that is both cheaper and more effective is of major importance. During the last year, acupuncture and Chinese medicine have been evaluated for this purpose. The results are summarized as follows: 1) Oral administration of 0.5 g of Ko-ken-huang-lien-huang-chin-tang (pueraria, coptis, scute and licorice combination) to piglets at 1 day old was effective in reducing incidence of infection (P less than 0.1) and increasing the body weight gain (P less than 0.05) during the first 10 days of life. Gentamycin or aqua-acupuncture at day 1 of life had no prophylactic value. 2) Piglets with preweaning diarrhea were treated by aqua-acupuncture at Chang-Chiang point (VG 1, or so called Chiao-Chao in traditional pig charts) with 0.2 ml of 3% saline, or by oral administration of 0.5 g of Ko-ken-huang-lien-huang-chin-tang or by injection of gentamycin (10 mg/piglet) twice a day for 1-3 days. These treatments significantly reduced the duration of illness (P less than 0.01) when compared with the control groups which received 0.5 g lactose orally. These results indicate that both acupuncture treatment and Chinese medicine have a high clinical value for controlling piglet diarrhea.

Synthesis of PbTe nanowire arrays using lithographically patterned nanowire electrodeposition.

We describe the preparation by electrodeposition of arrays of lead telluride (PbTe) nanowires using the lithographically patterned nanowire electrodeposition (LPNE) method. PbTe nanowires had a rectangular cross-section with adjustable width and height ranging between 60-400 nm (w) and 20-100 nm (h). The characterization of these nanowire arrays using X-ray diffraction, transmission electron microscopy and electron diffraction, scanning electron microscopy, atomic force microscopy, and X-ray photoelectron spectroscopy (XPS) is reported. PbTe nanowires were electrodeposited using a cyclic electrodeposition-stripping technique that produced polycrystalline, stoichiometric, face-centered cubic PbTe with a mean grain diameter of 10-20 nm. These nanowires were more than 1 mm in length and two additional processing steps permitted their suspension across 25 microm air gaps microfabricated on these surfaces. The LPNE synthesis of lithographically patterned PbTe nanowires was carried out in unfiltered laboratory air. Nanowires with lengths of 70-100 microm showed an electrical resistivity comparable to bulk PbTe. XPS reveals that exposure of PbTe nanowires to air causes the formation on the nanowire surface of approximately one monolayer of a mixed lead oxide and tellurium oxide within a few minutes.