Dissociation of intracellular lysosomal rupture from the cell death caused by silica

The relationship between intracellular lysosomal rupture and cell death caused by silica was studied in P388d(1) macrophages. After 3 h of exposure to 150 μg silica in medium containing 1.8 mM Ca(2+), 60 percent of the cells were unable to exclude trypan blue. In the absence of extracellular Ca(2+), however, all of the cells remained viable. Phagocytosis of silica particles occurred to the same extent in the presence or absence of Ca(2+). The percentage of P388D(1) cells killed by silica depended on the dose and the concentration of Ca(2+) in the medium. Intracellular lyosomal rupture after exposure to silica was measured by acridine orange fluorescence or histochemical assay of horseradish peroxidase. With either assay, 60 percent of the cells exposed to 150 μg silica for 3 h in the presence of Ca(2+) showed intracellular lysosomal rupture, was not associated with measureable degradation of total DNA, RNA, protein, or phospholipids or accelerated turnover of exogenous horseradish peroxidase. Pretreatment with promethazine (20 μg/ml) protected 80 percent of P388D(1) macrophages against silica toxicity although lysosomal rupture occurred in 60-70 percent of the cells. Intracellular lysosomal rupture was prevented in 80 percent of the cells by pretreatment with indomethacin (5 x 10(-5)M), yet 40-50 percent of the cells died after 3 h of exposure to 150 μg silica in 1.8 mM extracellular Ca(2+). The calcium ionophore A23187 also caused intracellular lysosomal rupture in 90-98 percent of the cells treated for 1 h in either the presence or absence of extracellular Ca(2+). With the addition of 1.8 mM Ca(2+), 80 percent of the cells was killed after 3 h, whereas all of the cells remained viable in the absence of Ca(2+). These experiments suggest that intracellular lysosomal rupture is not causally related to the cell death cause by silica or {"type":"entrez-nucleotide","attrs":{"text":"A23187","term_id":"833253","term_text":"A23187"}}A23187. Cell death is dependent on extracellular Ca(2+) and may be mediated by an influx of these ions across the plasma membrane permeability barrier damaged directly by exposure to these toxins.     

Extent of the selectivity filter conferred by the sixth transmembrane region in the CFTR chloride channel pore

Point mutations within the pore region of the cystic fibrosis transmembrane conductance regulator (CFTR) Cl(-) channel have previously been shown to alter the selectivity of the channel between different anions, suggesting that part of the pore may form an anion 'selectivity filter'. However, the full extent of this selectivity filter region and the location of anion binding sites in the pore are currently unclear. As a result, comparisons between CFTR and other classes of Cl(-) channel of known structure are difficult. We compare here the effects of point mutations at each of eight consecutive amino acid residues (arginine 334-serine 341) in the crucial sixth transmembrane region (TM6) of CFTR. Anion selectivity was determined using patch-clamp recording from inside-out membrane patches excised from transiently transfected mammalian cell lines. The results suggest that selectivity is predominantly controlled by a single site involving adjacent residues phenylalanine 337 and threonine 338, and that the selectivity conferred by this 'filter' region is modified by anion binding to flanking sites involving the more extracellular arginine 334 and the more intracellular serine 341. Other residues within this part of the pore play only minor roles in controlling anion permeability and conductance. Our results support a model in which specific TM6 residues make important contributions to a single, localized anion selectivity filter in the CFTR pore, and also contribute to multiple anion binding sites both within and on either side of the filter region.     

Paracrine effects of oocyte secreted factors and stem cell factor on porcine granulosa and theca cells <Emphasis Type="Italic">in vitro</Emphasis>

Oocyte control of granulosa and theca cell function may be mediated by several growth factors via a local feedback loop(s) between these cell types. This study examined both the role of oocyte-secreted factors on granulosa and thecal cells, cultured independently and in co-culture, and the effect of stem cell factor (SCF); a granulosa cell derived peptide that appears to have multiple roles in follicle development. Granulosa and theca cells were isolated from 2–6 mm healthy follicles of mature porcine ovaries and cultured under serum-free conditions, supplemented with: 100 ng/ml LR3 IGF-1, 10 ng/ml insulin, 100 ng/ml testosterone, 0–10 ng/ml SCF, 1 ng/ml FSH (granulosa), 0.01 ng/ml LH (theca) or 1 ng/ml FSH and 0.01 ng/ml LH (co-culture) and with/without oocyte conditioned medium (OCM) or 5 oocytes. Cells were cultured in 96 well plates for 144 h, after which viable cell numbers were determined. Medium was replaced every 48 h and spent medium analysed for steroids.     

High variation reduces the value of feather stable isotope ratios in identifying new wintering areas for aquatic warblers Acrocephalus paludicola in West Africa

Stable isotope analysis of feathers can be useful in the study of seasonal interactions and migratory connectivity in birds. For the Palaearctic–African migration system, however, the lack of isotope data from feathers of known origin in Africa renders the geographic assignment of birds captured on European breeding grounds to potential wintering areas problematic. Rectrices of the threatened aquatic warbler Acrocephalus paludicola grown in Africa were sampled across six European countries to assess whether birds in different breeding populations shared similar isotopic signatures and so were likely to have wintered in the same region in Africa. Freshly grown feathers of aquatic warblers collected at the only known wintering site in Senegal showed high variation in carbon, nitrogen, and hydrogen isotope ratios. Due to similarly high variation in isotope ratios of African‐grown feathers within all breeding populations, it was not possible to determine whether different populations wintered in different regions. However, isotope signatures of 20% of birds captured on European breeding grounds fell outside the range of those captured in Senegal, suggesting a wider wintering distribution than is currently known. We therefore assessed whether the origin of these feathers could be estimated by trying to establish isotopic gradients across sub‐Saharan West Africa. Feathers of three ecologically similar surrogate species were sampled from wetlands across a 3000 km east‐west and a 2000 km north–south transect. Within‐site variation in feather isotope ratios was frequently larger than the difference predicted by gradients across West Africa. Thus, predicting the origin of individual feathers using single‐isotope gradients was not reliable. The large within‐site variability of feather isotope ratios of a habitat specialist species like the aquatic warbler indicates that using feather isotope ratios will require large sample sizes from many locations, and may thus not be an efficient tool in identifying wintering areas of Palaearctic–African migrants.     

Training leading to repetition failure enhances bench press strength gains in elite junior athletes

The purpose of this study was to investigate the importance of training leading to repetition failure in the performance of 2 different tests: 6 repetition maximum (6RM) bench press strength and 40-kg bench throw power in elite junior athletes. Subjects were 26 elite junior male basketball players (n = 12; age = 18.6 +/- 0.3 years; height = 202.0 +/- 11.6 cm; mass = 97.0 +/- 12.9 kg; mean +/- SD) and soccer players (n = 14; age = 17.4 +/- 0.5 years; height = 179.0 +/- 7.0 cm; mass = 75.0 +/- 7.1 kg) with a history of greater than 6 months' strength training. Subjects were initially tested twice for 6RM bench press mass and 40-kg Smith machine bench throw power output (in watts) to establish retest reliability. Subjects then undertook bench press training with 3 sessions per week for 6 weeks, using equal volume programs (24 repetitions x 80-105% 6RM in 13 minutes 20 seconds). Subjects were assigned to one of two experimental groups designed either to elicit repetition failure with 4 sets of 6 repetitions every 260 seconds (RF(4 x 6)) or allow all repetitions to be completed with 8 sets of 3 repetitions every 113 seconds (NF(8 x 3)). The RF(4 x 6) treatment elicited substantial increases in strength (7.3 +/- 2.4 kg, +9.5%, p < 0.001) and power (40.8 +/- 24.1 W, +10.6%, p < 0.001), while the NF(8 x 3) group elicited 3.6 +/- 3.0 kg (+5.0%, p < 0.005) and 25 +/- 19.0 W increases (+6.8%, p < 0.001). The improvements in the RF(4 x 6) group were greater than those in the repetition rest group for both strength (p < 0.005) and power (p < 0.05). Bench press training that leads to repetition failure induces greater strength gains than nonfailure training in the bench press exercise for elite junior team sport athletes.     

Phylogenetic analysis of the tenascin gene family: evidence of origin early in the chordate lineage

Background  

Tenascins are a family of glycoproteins found primarily in the extracellular matrix of embryos where they help to regulate cell proliferation, adhesion and migration. In order to learn more about their origins and relationships to each other, as well as to clarify the nomenclature used to describe them, the tenascin genes of the urochordate Ciona intestinalis, the pufferfish Tetraodon nigroviridis and Takifugu rubripes and the frog Xenopus tropicalis were identified and their gene organization and predicted protein products compared with the previously characterized tenascins of amniotes.     

Fractures on the chest radiograph in detection of alcoholic liver disease.

The presence of fractures seen on routine chest radiography was assessed in patients with liver disease to see whether it might provide a useful marker of alcoholism. Chest radiographs taken at the time of liver biopsy were examined in 149 patients--72 with alcoholic liver disease (32 (44%) cirrhotic) and 77 with various forms of non-alcoholic liver disease (15 (19 . 5%) cirrhotic)--and in 149 controls. Fractures (85 rib, two clavicular) were much more common in patients with alcoholic liver disease (20 subjects; 28%) than in patients with non-alcoholic liver disease (1; 1 . 3%) or controls 10; 6 . 7%). In alcoholic liver disease rib fractures were significantly more likely to be bilateral or multiple (more than two) or both (p less than 0 . 01). Of patients with alcoholic liver disease, those with fractures were significantly older than those without, but there was no difference in sex, social class, the proportion with cirrhosis, or the proportion known to be alcoholic at the time of the radiograph. In liver disease fractures on the chest radiograph diagnosed alcoholism with 95% specificity and 28% sensitivity. These often overlooked or ignored findings in the chest radiograph may have a wider role in the detection of alcoholism.     

Drivers of aboveground wood production in a lowland tropical forest of West Africa: teasing apart the roles of tree density,tree diversity,soil phosphorus,and historical logging

Tropical forests currently play a key role in regulating the terrestrial carbon cycle and abating climate change by storing carbon in wood. However, there remains considerable uncertainty as to whether tropical forests will continue to act as carbon sinks in the face of increased pressure from expanding human activities. Consequently, understanding what drives productivity in tropical forests is critical. We used permanent forest plot data from the Gola Rainforest National Park (Sierra Leone) – one of the largest tracts of intact tropical moist forest in West Africa – to explore how (1) stand basal area and tree diversity, (2) past disturbance associated with past logging, and (3) underlying soil nutrient gradients interact to determine rates of aboveground wood production (AWP). We started by statistically modeling the diameter growth of individual trees and used these models to estimate AWP for 142 permanent forest plots. We then used structural equation modeling to explore the direct and indirect pathways which shape rates of AWP. Across the plot network, stand basal area emerged as the strongest determinant of AWP, with densely packed stands exhibiting the fastest rates of AWP. In addition to stand packing density, both tree diversity and soil phosphorus content were also positively related to productivity. By contrast, historical logging activities negatively impacted AWP through the removal of large trees, which contributed disproportionately to productivity. Understanding what determines variation in wood production across tropical forest landscapes requires accounting for multiple interacting drivers – with stand structure, tree diversity, and soil nutrients all playing a key role. Importantly, our results also indicate that logging activities can have a long‐lasting impact on a forest's ability to sequester and store carbon, emphasizing the importance of safeguarding old‐growth tropical forests.     

Ultrasonography compared with intravenous urography in the investigation of adults with haematuria.

OBJECTIVE--To compare ultrasonography with intravenous urography in the investigation of adults with haematuria. DESIGN--Prospective study entailing the examination of all patients with both investigations concurrently. The investigations were performed independently on routine lists by different duty radiologists. Each was aware of the details of the request form but not of the findings of the other investigation. SETTING--Radiology department of a teaching hospital. PATIENTS--155 Consecutive adult patients (aged 18-93) referred from general practitioners and hospital outpatient clinics with a history of haematuria. FOLLOW UP--When results of both examinations proved normal no clinical or radiological follow up was sought. All abnormal findings of either investigation were correlated with results of subsequent imaging studies or operative findings. RESULTS--81 Patients (52%) had normal findings on urography and ultrasonography. Overall, the findings of ultrasonography concurred with those of urography in 144 cases (93%). Among the discrepant findings of the two investigations ultrasonography missed two ureteric calculi; one was in a non-dilated ureter, and in the other case ultrasonography detected the secondary ureteric dilatation. Ultrasound examination alone detected four bladder tumours not visible on urography with sizes ranging from 5 to 21 mm, representing one fifth of the 20 cystoscopically proved bladder tumours detected in the series. Ultrasonography detected all the 22 neoplastic lesions discovered in the study (20 bladder, two renal). Ultrasonography clarified the nature of renal masses evident in three urograms (simple cysts). CONCLUSIONS--Ultrasonography is a safe and accurate method of investigating the urinary tract in adults with haematuria. When combined with a single plain abdominal radiograph it proved to be superior to urography as the primary imaging study in this series. Ultrasonography should certainly be preferred to urography if cystoscopy is not planned. No urothelial tumours of the upper urinary tract were found in the series, reflecting their rarity. For those patients in whom ultrasonography and plain radiography have shown no abnormality and in whom cystoscopic appearances are normal urography would be advisable to exclude urothelial tumours of the upper urinary tract.