Effects of vasectomy on spermatogenesis and fertility outcome after testicular sperm extraction combined with ICSI.

BACKGROUND: Each year 40,000 men have a vasectomy in the UK whilst another 2400 request a reversal to begin a second family. Sperm can now be obtained by testicular biopsy and subsequently used in assisted conception with ICSI. The study aims were to compare sperm yields of men post-vasectomy or with obstructive azoospermia (OA) of unknown aetiology with yields of fertile men and to assess any alteration in the clinical pregnancy rates after ICSI. METHODS: Testicular tissue was obtained by Trucut needle from men who had undergone a vasectomy >5 years previously or had OA from other causes and from fertile men during vasectomy. Seminiferous tubules were milked to measure sperm yields. Numbers of Sertoli cells and spermatids and thickness of the seminiferous tubule walls were assessed using quantitative computerized analysis. RESULTS AND CONCLUSIONS: Sperm yields/g testis were significantly decreased in men post-vasectomy and in men with OA, relative to fertile men. Significant reductions were also observed in early (40%) and mature (29%) spermatid numbers and an increase of 31% was seen in the seminiferous tubule wall (basal membrane and collagen thickness) of vasectomized men compared with fertile men. Clinical pregnancy rates in couples who had had a vasectomy were also significantly reduced.

Pattern and process in Amazon tree turnover, 1976-2001.

Previous work has shown that tree turnover, tree biomass and large liana densities have increased in mature tropical forest plots in the late twentieth century. These results point to a concerted shift in forest ecological processes that may already be having significant impacts on terrestrial carbon stocks, fluxes and biodiversity. However, the findings have proved controversial, partly because a rather limited number of permanent plots have been monitored for rather short periods. The aim of this paper is to characterize regional-scale patterns of 'tree turnover' (the rate with which trees die and recruit into a population) by using improved datasets now available for Amazonia that span the past 25 years. Specifically, we assess whether concerted changes in turnover are occurring, and if so whether they are general throughout the Amazon or restricted to one region or environmental zone. In addition, we ask whether they are driven by changes in recruitment, mortality or both. We find that: (i) trees 10 cm or more in diameter recruit and die twice as fast on the richer soils of southern and western Amazonia than on the poorer soils of eastern and central Amazonia; (ii) turnover rates have increased throughout Amazonia over the past two decades; (iii) mortality and recruitment rates have both increased significantly in every region and environmental zone, with the exception of mortality in eastern Amazonia; (iv) recruitment rates have consistently exceeded mortality rates; (v) absolute increases in recruitment and mortality rates are greatest in western Amazonian sites; and (vi) mortality appears to be lagging recruitment at regional scales. These spatial patterns and temporal trends are not caused by obvious artefacts in the data or the analyses. The trends cannot be directly driven by a mortality driver (such as increased drought or fragmentation-related death) because the biomass in these forests has simultaneously increased. Our findings therefore indicate that long-acting and widespread environmental changes are stimulating the growth and productivity of Amazon forests.

Concerted changes in tropical forest structure and dynamics: evidence from 50 South American long-term plots.

Several widespread changes in the ecology of old-growth tropical forests have recently been documented for the late twentieth century, in particular an increase in stem turnover (pan-tropical), and an increase in above-ground biomass (neotropical). Whether these changes are synchronous and whether changes in growth are also occurring is not known. We analysed stand-level changes within 50 long-term monitoring plots from across South America spanning 1971-2002. We show that: (i) basal area (BA: sum of the cross-sectional areas of all trees in a plot) increased significantly over time (by 0.10 +/- 0.04 m2 ha(-1) yr(-1), mean +/- 95% CI); as did both (ii) stand-level BA growth rates (sum of the increments of BA of surviving trees and BA of new trees that recruited into a plot); and (iii) stand-level BA mortality rates (sum of the cross-sectional areas of all trees that died in a plot). Similar patterns were observed on a per-stem basis: (i) stem density (number of stems per hectare; 1 hectare is 10(4) m2) increased significantly over time (0.94 +/- 0.63 stems ha(-1) yr(-1)); as did both (ii) stem recruitment rates; and (iii) stem mortality rates. In relative terms, the pools of BA and stem density increased by 0.38 +/- 0.15% and 0.18 +/- 0.12% yr(-1), respectively. The fluxes into and out of these pools-stand-level BA growth, stand-level BA mortality, stem recruitment and stem mortality rates-increased, in relative terms, by an order of magnitude more. The gain terms (BA growth, stem recruitment) consistently exceeded the loss terms (BA loss, stem mortality) throughout the period, suggesting that whatever process is driving these changes was already acting before the plot network was established. Large long-term increases in stand-level BA growth and simultaneous increases in stand BA and stem density imply a continent-wide increase in resource availability which is increasing net primary productivity and altering forest dynamics. Continent-wide changes in incoming solar radiation, and increases in atmospheric concentrations of CO2 and air temperatures may have increased resource supply over recent decades, thus causing accelerated growth and increased dynamism across the world's largest tract of tropical forest.

Failed total hip replacement: assessment by plain radiographs, arthrograms, and aspiration of the hip joint.

We reviewed a series of sixty-one revised total hip replacements in order to assess the accuracy of plain radiographs (all hips), arthrograms (thirty-one hips), and aspiration (sixty hips) in demonstrating the presence of loosening or infection. Plain radiographs correctly showed the status of the fixation of 92 per cent of the femoral components but of only 63 per cent of the sockets. They indicated loosening in only 37 per cent of the loose sockets. Arthrography improved the over-all accuracy in demonstrating the status of the fixation of the sockets to 80 per cent and increased the accurate detection of loose sockets to 89 per cent; however, it was no more useful than the plain radiographs in the assessment of the femoral components. Aspiration of the joint proved reliable in excluding the possibility of infection in fifty-nine of sixty hips. We concluded that femoral components are best evaluated for loosening by plain radiographs, but arthrography substantially improves the diagnostic accuracy for loosening of the socket. Aspiration of the joint accurately excluded sepsis as the cause of pain in all of the hips from which joint fluid was obtained.

Femoral component loosening using contemporary techniques of femoral cement fixation.

A radiographic study was done of 171 total hip replacements that had been followed for an average of 3.3 years (range, two to five years). The study was performed to assess the incidence of loosening of the femoral component in older adult patients (average age, sixty years) in whom the medullary canal had been plugged with methylmethacrylate (using the medullary plug syringe to introduce the plug) prior to introducing the cement (Simplex P) with a cement-gun. Most of the femoral components that were used were of the CAD or HD-2 design, and all were made of chromium-cobalt alloy. Three categories of loosening were defined: definite (requiring radiographic evidence of migration of the component or the cement), probable (requiring evidence of complete 100 per cent radiolucent zone around the cement mantle on one or more radiographs), and possible (requiring evidence of a radiolucent zone that occupied more than 50 but less than 100 per cent of the cement-bone interface on one or more radiographs). One hip required revision for a loose femoral component and another patient had asymptomatic subsidence of the femoral component. Thus, the total incidence of definitely loose femoral components was 1.1 per cent. No hip was classified as having probable loosening; seven hips (4 per cent) were rated as having possible loosening. Compared with the results of four other published reports of patients of similar age with similar follow-up, and using the same radiographic criterion for loosening, the current series demonstrated a statistically significant reduction in the incidence of definitely loose femoral components.

Loosening of the femoral component of total hip replacement after plugging the femoral canal.

A roentgen follow-up study was done of 171 total hip replacements at an average of 3.3 years (range 2 to 5 years) after insertion to assess the loosening rate in older adult patients (average age 60 years) in whom the medullary canal was plugged. The cement (Simplex P) was introduced using a cement gun. The femoral components used were CAD and HD-2 in design, made of chrome cobalt alloy. Evaluation was made according to three categories of loosening: definite (requiring evidence of migration of the component or the cement), probable (requiring a continuous radiolucent zone around the cement mantle in one or more radiographic views), or possible (requiring a radiolucent zone that occupied 50% or more of the cement-bone interface in one or more views but was not continuous). One hip was revised for a loose femoral component. Another patient has asymptomatic subsidence of the femoral component. Thus the total incidence of definitely loose femoral components was 1.1%. No hip was classified as probably loose. Seven hips (4%) were rated as possibly loose. Compared to four other reported series of similar groups of patients followed for like duration, this incidence of definitely loose components is statistically significantly less than in nonplugged canals. The other differences among the series compared, such as stem design, type of cement introduction, modulus of elasticity of the metal used, presence or absence of a collar, and dates during which the surgery was done, are also discussed. Plugging the femoral canal; introducing the cement with a cement gun; using a femoral stem that largely fills the medullary canal, has a collar, and has a rounded rectangular cross section with no medial stress risers made of a superalloy with a modulus of elasticity of about 200 GPa--all these factors were associated with a low (1.1%) incidence of femoral component loosening at 3 years.

Early roentgenographic evaluation of bowlegged children.

Thirty-nine knees in 21 bowlegged children under the age of 30 months were examined roentgenographically at initial clinic visit. All were followed until bowing resolved, bowing persisted past age 30 months, or surgery was performed. Older bowlegged children had strikingly poorer prognoses. We identified (a) longer fibula than tibia and (b) more acute proximal tibial angulation than distal femoral angulation as possible prognostic signs that bowing was likely to persist. Bowlegs in girls seem less likely to resolve spontaneously than in boys. Race does not seem to be a factor. The initial examiner's interpretation of roentgenograms as "physiologic bowlegs" or "Blount's disease" was not found to be reliable.