Clinical biomechanic correlates of cervical dysfunction: Part 4. Altered regional motor behavior

The in vitro effect of zinc on superoxide anion (O2-) generation and on experimentally induced lipid peroxidation (LPO) in spermatozoa of infertile men was investigated. Washed spermatozoa pre-incubated for 30 min at 37 degrees C in the presence of 1 or 3 mmol l-1 zinc, released less superoxide anions (P < 0.03 and P < 0.02, respectively; n = 9) than the untreated spermatozoa. Similar results were obtained using activated polymorphonuclear leukocytes (1 x 10(6) cells ml-1) in the presence of 1 or 3 mmol l-1 Zn (P < 0.001 and P < 0.0002, respectively; n = 9). The in vitro evidence of the inhibitory effect of zinc on O2- generation by human spermatozoa and leukocytes indicates that zinc may act in vivo as a scavenger of excessive O2- production by defective spermatozoa and/or leukocytes in semen after ejaculation. A significant stimulatory effect of Zn (3 mmol l-1) on iron-induced lipid peroxidation, measured by the formation of thiobarbituric acid reactive substances (TBARS), was detected in the spermatozoa of 16 normo- and 17 asthenozoospermic males (P < 0.0001 and P < 0.001, respectively). In 11 samples with sperm concentration 20.3 +/- 2.1 x 10(6) ml-1, exhibiting initial TBARS concentration two times higher than in normo- and asthenozoospermic samples (40.5 +/- 2.4 vs. 17.1 +/- 1.1 and 28.5 +/- 4.1 nmoles TBARS 10(-8) spermatozoa), no effect of zinc on the LPO rate was found. The observed inhibitory effect of zinc on superoxide anion regardless of the initial O2- level and stimulatory effect of zinc depending on the initial LPO rate in human spermatozoa suggests that this metal ion participates in the oxidative changes occurring after ejaculation and thus may modulate the properties of germ cells.     

Photosensitive polynorbornene based dielectric. II. Sensitivity and spatial resolution

Photodefinable poly(decylnorbornene‐co‐epoxidenorbornene) copolymer has been developed as a dielectric material for electronic packaging applications. The photodefinition properties of the polymer are affected by the copolymer composition, the concentration of photoactive compound and the process conditions. In particular, ultra‐high contrast conditions were found to promote the fabrication of vertical sidewall structures. For photodefined structures, the vertical sidewalls were obtained at specific formulations and process conditions. Under different conditions, non‐vertical features were observed. Rutherford backscattering analysis (RBS), X‐ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) were used to study the photodefinition properties. In this article, a mechanism based on the diffusion of photoactive compounds from the exposed area to the unexposed area is presented. The transport of photoactive compounds takes place through the free volume that results from solvent evaporation. The diffusion of the photoactive compounds to the surface of the polymer film results in a higher concentration of photogenerated acid at the surface. The movement of the photoactive compounds occurs in both the in‐plane and through‐plane directions. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3031–3039, 2004     

Nonlinear electronic dynamics in free and deposited sodium clusters: Quantal and semi-classical approaches

The optical response of sodium clusters is studied using fully three-dimensional electronic dynamics, in real time, with an explicit ionic background. The obtained spectra are shown to come close to experimental results for free clusters. We use the approach also to compute the response of sodium clusters deposited on a NaCl(1 0 0) surface. The flattening of the clusters induced by the surface results in a shift and a large fragmentation of the plasmon resonance.     

Primary intraocular posttransplantation lymphoproliferative disorder

We report a case of posttransplantation lymphoproliferative disorder manifesting as an isolated, unilateral iris tumor. A 2-year-old boy who had undergone liver transplantation for biliary atresia at age 4 months was seen with a 2-month history of an enlarging iris nodule. Histopathologic examination of the iris lesion demonstrated a mixed population of lymphoid cells. To our knowledge, this is the youngest patient with posttransplantation lymphoproliferative disorder isolated to the eye.     

Correlation of MRI and arthroscopic diagnosis of knee pathology in children and adolescents

The accuracy of magnetic resonance imaging (MRI) in diagnosing knee pathology in the pediatric and adolescent population is not well established. The purpose of this study was to correlate the findings of MRI and knee arthroscopy in children and adolescents. One hundred and eight consecutive knee arthroscopies performed in patients ages 4-17 years between 1992 and 1996 were retrospectively reviewed. Fifty-three of these patients underwent preoperative MRI. Age-related comparisons were then made between MRIs and observed intraoperative meniscal and anterior cruciate ligament pathology. The pediatric group (ages 4-14 years) was demonstrated to have an appreciable decrease in sensitivity, specificity, positive predictive value, and accuracy for essentially all categories of pathologic changes. Conversely, negative predictive values for the pediatric group exceeded those of the adolescent group (ages 15-17 years) in each category. The ability of MRI to predict intraarticular knee pathology among adolescents is comparable to that in adults, whereas it is much less accurate in the pediatric population.     

Electrostatic actuators with expanded tuning range due to biaxial intrinsic stress gradients

A stress gradient was induced in two directions (through the plane of the beam and along its length) to produce a beam deflection of varying curvature. The stress gradient in the through-plane direction was produced by altering the conditions during electroplating and in the in-plane direction through lithographic patterning. The pull-down characteristics of four electrostatic actuator designs were analyzed. The in-plane stress gradient, along the length of the beam, significantly improved the tuning range compared with devices containing spatially uniform stress. This advance has greatly eased the instability problem of electrostatically actuated beams. The tuning range of a device with two hinges and a square front improved from less that 33% to 70%. Devices with two hinges and elliptical front improved to 45% tuning range and those with rectangular shape improved to 65% stability. This advance has been applied to actuators for RF tuners. Voltage cycling impacted only the initial cycling of the actuator.     

Gonadal hormones and gonadotropin-releasing hormone (GnRH) alter messenger ribonucleic acid levels for GnRH receptors in sheep

GnRH regulates the synthesis and secretion of pituitary gonadotropins. The number of receptors for GnRH (GnRH-rec) can vary from 500 to 15,000-20,000/gonadotrope in ovine pituitary cultures after treatment with physiologically relevant combinations of gonadal hormones. This large range suggests that regulation of GnRH-rec expression may be an important control point in GnRH action at the pituitary level. Reported here are the changes in GnRH-rec mRNA associated with pituitary treatments (48 h) of 17 beta-estradiol (E), progesterone (P), and an enriched preparation of porcine follicular inhibin (IN). Northern blot analysis was used to detect 3 species of GnRH-rec mRNA in primary ovine pituitary culture [5.5 kilobases (kb; 32%), 3.6 kb (51%), and 1.4 kb (17%)]; all were changed in parallel by E, P, and IN. GnRH-rec mRNAs were increased 190% over control levels after treatment with either E or IN, and 400% with E and IN combined; when E and IN were added along with P, the increase was only 50% (P caused an 87% inhibition of E plus IN induction). The addition of P in the absence of any other treatment reduced levels of GnRH-rec mRNA by 50%. Studies were also conducted with GnRH agonists (GnRH-A) due to their widespread clinical use for down-regulating reproductive function in men and women. The addition of GnRH-A to cultures was as effective as P in blocking E plus IN induction of GnRH-rec mRNA. In vivo studies in wethers showed that 7 days of chronic treatment with GnRH-A decreased all sizes of ovine GnRH-rec mRNA by 84-89%. These data indicate that E, P, and IN change GnRH-rec levels at least in part by changing levels of GnRH-rec mRNAs. They also show that GnRH-A can almost entirely block E plus IN induction of GnRH-rec mRNA in vitro and decrease levels of GnRH-rec mRNA in vivo in wethers.     

Photodefinable Epoxycyclohexyl Polyhedral Oligomeric Silsesquioxane

A photodefinable dielectric was developed using epoxycyclohexyl polyhedral oligomeric silsesquioxanes (POSS) and a photocatalyst. POSS is a hybrid organic/inorganic dielectric which has favorable mechanical and chemical stability for use as a permanent dielectric in microfabrication. Sharp, 10 μm wide features were formed from POSS using 365 nm radiation. The optical contrast was 1.51. POSS films were thermally stable to 350°C and demonstrated chemical stability in a variety of solvents and oxidants. The polymer film had an elastic modulus of 5.3 GPa and a hardness of 0.64 GPa. The POSS had high etch selectivity compared with organic films for pattern transfer.