A prospective study of multiple needle biopsies versus a single open biopsy for testicular sperm extraction in men with non-obstructive azoospermia

To identify the predictive factors for testicular sperm extraction (TESE) and to understand the pathology associated with TESE, we carried out a prospective study in 40 consecutive men with azoospermia due to primary gonadal failure. The main outcome measure was the retrieval of at least one testicular spermatozoon. Endocrine and biophysical profiles, testicular histology, Johnsen score and testicular spermatids were used as predictors of sperm extraction. Spermatogenesis was quantified with the Johnsen score. A variable pattern of spermatogenesis was common, being present in 20 (50%) patients. Visualisation of testicular spermatids on testicular histology showed a strong association with TESE (P < 0.0001). Statistically significant differences were detected in plasma follicle stimulating hormone (FSH) and testicular volume between patients who had hypospermatogenesis and Sertoli cell-only or maturation arrest. There were no significant differences in Johnsen score, biophysical and endocrine profiles between the groups with successful and failed TESE. However, a statistically significant trend occurred with changes in histological pattern [chi2 for trend, P = 0.001; Pearson's coefficient (r) = 0.6], Johnsen score (P = 0.022; r = 0.5), testicular volume (P = 0.01; r = 0.5) and plasma FSH concentrations (P = 0.044; r = 0.4), albeit to a limited degree. Difference in the interpretation of histological patterns with different assessors was observed. The type of occupation or risk factors for azoospermia showed no association with testicular pathology or TESE. Variable histological patterns in different tubules in the same individual may explain the poor correlation of TESE with endocrine and biophysical profiles, Johnsen score and histological pattern. Differences in the amount of tissue used for TESE and histopathology, and misinterpretation of testicular histology rather than failure to quantify spermatogenesis may explain the poor correlation between histological patterns and TESE. Testicular spermatids predicted TESE. However, considerable overlap in values means that no single variable can provide a perfect discrimination between the groups with successful and failed TESE.     

Charge, current, and noise partitioning in MOSFET in the presence of mobility degradation

The Ward-Dutton (WD) partitioning scheme is used extensively to develop transient and high-frequency advanced compact models in MOSFET analysis. However, it remains an open question if this scheme can be used for field-dependent mobility that is enhanced in state-of-the-art submicrometer technologies. In this paper, after demonstrating that the well-known WD partitioning is indeed invalid for field-dependent mobility, the authors develop a very general partitioning strategy that can always be defined in small-signal analysis for any arbitrary velocity-field relationship. It has also been shown that for large-signal operation, the existence of a partitioning scheme can be determined by the solution of an integral equation.     

Influence of sputter deposition parameters on the properties of tunable barium strontium titanate thin films for microwave applications

Barium strontium titanate (BST) thin films are studied with respect to their application as tunable dielectric at microwave frequencies. BST thin films are deposited by means of radio-frequency magnetron sputtering on platinized Si substrates. The substrate to target distance during sputter deposition is varied and the effect on structure, topology, composition and electronic properties is monitored using X-ray diffraction, atomic force microscopy, Rutherford backscattering spectrometry and X-ray photoelectron spectroscopy. These findings are related to the dielectric measurements, which are carried out at 1 MHz and in the microwave range up to 8 GHz using metal-insulator-metal structures with Pt electrodes. For further device evaluation, leakage current measurements are carried out. Changing the process parameter strongly affects the composition of the films. The results emphasize the possibility for enhancing the microwave properties by fine-tuning of the chosen process parameter.     

Common-mode oscillation in capacitivecoupled differential Colpitts oscillators

A simple approach to the realisation of a differential Colpitts oscillator is to connect the grounded capacitor in the feedback network of two single-ended Colpitts oscillators together in series. As the output signals are expected to be differential, it is proved in this Letter that, this is not always the case. In certain circumstances, this topology exhibits a common-mode output signal, or even worse, a combination between differential-mode and common-mode waveforms. Design criteria for avoiding these undesirable oscillating behaviours are derived by considering the start-up characteristic of the oscillator.     

Design of high-Q varactors for low-power wireless applicationsusing a standard CMOS process

New applications such as wireless integrated network sensors (WINS) require radio-frequency transceivers consuming very little power compared to usual mainstream applications, while still working in the ultra-high-frequency range. For this kind of application, the LC-tank-based local oscillator remains a significant contributor to the overall receiver power consumption. This statement motivates the development of good on-chip varactors available in a standard process. This paper describes and compares the available solutions to realize high-Q, highly tunable varactors in a standard digital CMOS submicrometer process. On this basis, quality factors in excess of 100 at 1 GHz, for a tuning ratio reaching two, have been measured using a 0.5-μm process     

Simple topology for low-voltage and low-power RF quadrature oscillators

A design technique for implementing a low-voltage and low-power quadrature oscillator operating at radio frequencies is proposed. The oscillator utilises a cascade of four stages of capacitive-source amplifiers to generate balanced quadrature signals. The analysis provides a set of design equations that matches the simulation results.     

Inhibition of protein synthesis by zinc: comparison between protein synthesis and RNA synthesis

Inhalation of zinc fumes may lead to the acute respiratory distress syndrome. The mechanisms of pulmonary zinc toxicity are not yet understood. Therefore we investigated zinc-dependent depression of protein and RNA synthesis in rat and human lung cell lines. 1. After exposure to 120 or 150 micromol/l zinc, RNA synthesis as assessed by uridine incorporation decreased by 60-70% between 0 and 2 h exposition in rat alveolar type II cells (L2 cells) and human fibroblast-like cells (11Lu and 16Lu cells), and by 90% between 0 and 4 h in carcinoma-derived cells (A549 cells). 2. After 2 h exposure, L2, 11Lu, and 16Lu cells were half-maximally inhibited by 50 micromol/l zinc, whereas A549 cells were more resistant with half-maximal inhibition at 100 micromol/zinc. 3. Protein and RNA synthesis was inhibited in parallel in L2, 11Lu, and A549 cells as indicated by simultaneous determination of uridine and amino acid incorporation. In 16Lu cells, the decline in protein synthesis preceded RNA synthesis inhibition. Pretreatment with RNA synthesis inhibitors (amanitin or actinomycin D) had no effect on time curve and intensity of RNA synthesis inhibition. Taken together, our results indicate that the suppression of RNA and protein synthesis likely are independent phenomena, due to direct zinc effects on these biosynthetic pathways.     

Injuries among domestic waste collectors

In a recent paper [R.R. Holson, J.F. Bowyer, P. Clausing, B. Gough, Methamphetamine-stimulated striatal dopamine release declines rapidly over time following microdialysis probe insertion, Brain Res. 739 (1996) 301-307] we reported that methamphetamine-stimulated striatal dopamine release declined rapidly over the first eight hours following microdialysis probe insertion. This decline was strictly a function of time post-probe implantation, and not due to tolerance or desensitization. To further examine this phenomenon, we subjected rats to three brief pulses of several DA-releasing compounds at 2, 4 and 6 h post-probe insertion, and compared these results to those caused by a single pulse 6 h post-insertion, or in some cases to pulses given more than 24 h post-insertion. We found that when buproprion, a dopamine reuptake blocker, was infused briefly into the striatum via the microdialysis probe, there was a pronounced drop in the amount of dopamine released at 6 h vs. 2 h post-insertion; this drop was not due to repeated exposure, since dopamine release at 6 h post-insertion was the same for a single pulse, or when preceded by two earlier pulses. Twenty-four hours later, buproprion-stimulated dopamine release was still lower, but did not appear to drop further thereafter. Potassium-stimulated dopamine release, on the other hand, dropped rapidly over the first 8 h post-insertion, and this decline continued throughout the 24-32 h interval post-insertion. Similarly, a single i.p. injection of 0.5 mg/kg haloperidol released three times as much dopamine when given two compared to six hours post-implantation. Both bupropion- and potassium-stimulated dopamine release were accompanied by declines in extracellular DOPAC concentrations, and these declines were the same 2 or 26 h post-insertion. In contrast, haloperidol exposure increased extracellular DOPAC, and this haloperidol-stimulated DOPAC increase was also greatly attenuated at 6 compared to 2 h post-insertion. We conclude that there is a general decline over time post-probe implantation in the ability of the striatal dopamine system to release dopamine, and perhaps to increase dopamine synthesis, in response to pharmacological challenges.