Inhibition of sperm motility does not affect live-dead separation of bull sperm by glass beads.
(33/517)
AIM: This study was designed to explore factors which influence binding of dead versus live sperm to glass filters. METHODS: Multiple semen collections from bulls were used to explore selective filtration of bull sperm as influenced by nonlethal inhibition of sperm motility with fluoride, killing of sperm by quick-freezing, alteration of the glass surface with silicone, and different intervals of sexual rest between semen collections. RESULTS: A comparison of glass spheres 100, 200 and 390 microm in diameter indicated that 200 microm spheres were optimal for selective filtration. Quantitative separation of live from dead sperm was demonstrated with a correlation between the percentage of motile sperm and retention of sperm by the filter of r = -0.87 (P < 0.05). Up to 0.02 mol/L NaFl did not alter the proportion of sperm retained by the filter despite inhibiting sperm motility during filtration, an inhibition which was reversible. Proportions of live-dead sperm, based upon eosin staining, were unaffected by fluoride. Coating the glass spheres with silicone greatly reduced selective filtration. Dead sperm adherence to glass was reduced and resistance to NaFl inhibition was increased by daily ejaculation versus one-week intervals of sexual rest. CONCLUSION: These studies indicate that the adherence of sperm to glass is primarily due to some form of physico-chemical change accompanying death of the sperm cell independent of active sperm motility. This attraction between the sperm plasma membrane and glass is modified by the age of the ejaculated sperm. This information is useful in evaluating different clinical procedures used for sperm separation. (+info)
Use of the silicone T-tube to treat tracheal stenosis or tracheal injury.
(34/517)
BACKGROUND: Tracheal stenosis or tracheal injury is a troublesome disease. Traditional temporary tracheostomy and reconstruction can resolve some problems. However other problems such as subglottic stenosis and supracarinal stenosis, cannot be resolved by simple tracheostomy. The silicone tracheal T-tube presents a substitute for stent of this complicated disease. METHODS: Eleven patients with tracheal stenosis or tracheal injury were managed with the silicone T-tube prosthesis from 1995 to 1999. Among them 5 cases were characterized by subglottic and cervical stenosis, 4 cases supracarinal stenosis, and 2 cases tracheal injury. The silicone T-tube was used for about one year in all patients with satisfactory results. RESULTS: One patient was excluded from the study because of death due to unrelated disease. The T-tubes were removed successfully one year later. Among them, two patients with granuloma over the subglottic area were treated by CO(2) laser 2 to 4 times. The stoma was closed by repeated silver nitrate application. CONCLUSIONS: The silicone T-tube is a useful prosthesis for tracheal stenosis or tracheal injury with minimal complication in place of traditional tracheostomy or complex tracheal reconstruction. (+info)
Potential risk factors for undifferentiated connective tissue disease among women: implanted medical devices.
(35/517)
A case-control study was conducted among 205 women in Michigan and Ohio who were diagnosed with undifferentiated connective tissue disease (UCTD) to investigate the significance of self-reported past exposures to implanted silicone-containing or non-silicone-containing medical devices. The 205 UCTD cases were compared with 2,095 controls who were sampled by random digit dialing. When silicone-containing devices, including shunts and catheters, were analyzed collectively, a significant association was observed (odds ratio (OR) = 2.81, 95% confidence interval (CI): 1.34, 5.89). The odds ratio for exposure to breast implants was increased, but not significantly (OR = 2.22, 95% CI: 0.65, 7.57). Among the non-silicone-containing devices, artificial joints (OR = 5.01, 95% CI: 1.60, 15.71) and orthopedic metallic fixation devices (OR = 1.95, 95% CI: 1.05, 3.60) were associated with UCTD. The estimations of risk associated with implanted medical devices in UCTD cases were explored in a comparison with 660 scleroderma patients who were ascertained concurrently in Michigan and Ohio. In general, the associations that were observed with non-silicone-containing devices, and more specifically with the fixation devices, persisted in the comparison of UCTD cases with scleroderma patients. The studies conducted among populations in Michigan and Ohio are intended to stimulate new hypotheses, innovative approaches, and the fostering of understanding of the environmental determinants of autoimmune disease. (+info)
Characterization of phenotypic changes in Pseudomonas putida in response to surface-associated growth.
(36/517)
The formation of complex bacterial communities known as biofilms begins with the interaction of planktonic cells with a surface. A switch between planktonic and sessile growth is believed to result in a phenotypic change in bacteria. In this study, a global analysis of physiological changes of the plant saprophyte Pseudomonas putida following 6 h of attachment to a silicone surface was carried out by analysis of protein profiles and by mRNA expression patterns. Two-dimensional (2-D) gel electrophoresis revealed 15 proteins that were up-regulated following bacterial adhesion and 30 proteins that were down-regulated. N-terminal sequence analyses of 11 of the down-regulated proteins identified a protein with homology to the ABC transporter, PotF; an outer membrane lipoprotein, NlpD; and five proteins that were homologous to proteins involved in amino acid metabolism. cDNA subtractive hybridization revealed 40 genes that were differentially expressed following initial attachment of P. putida. Twenty-eight of these genes had known homologs. As with the 2-D gel analysis, NlpD and genes involved in amino acid metabolism were identified by subtractive hybridization and found to be down-regulated following surface-associated growth. The gene for PotB was up-regulated, suggesting differential expression of ABC transporters following attachment to this surface. Other genes that showed differential regulation were structural components of flagella and type IV pili, as well as genes involved in polysaccharide biosynthesis. Immunoblot analysis of PilA and FliC confirmed the presence of flagella in planktonic cultures but not in 12- or 24-h biofilms. In contrast, PilA was observed in 12-h biofilms but not in planktonic culture. Recent evidence suggests that quorum sensing by bacterial homoserine lactones (HSLs) may play a regulatory role in biofilm development. To determine if similar protein profiles occurred during quorum sensing and during early biofilm formation, HSLs extracted from P. putida and pure C(12)-HSL were added to 6-h planktonic cultures of P. putida, and cell extracts were analyzed by 2-D gel profiles. Differential expression of 16 proteins was observed following addition of HSLs. One protein, PotF, was found to be down-regulated by both surface-associated growth and by HSL addition. The other 15 proteins did not correspond to proteins differentially expressed by surface-associated growth. The results presented here demonstrate that P. putida undergoes a global change in gene expression following initial attachment to a surface. Quorum sensing may play a role in the initial attachment process, but other sensory processes must also be involved in these phenotypic changes. (+info)
Bioavailability of octamethylcyclotetrasiloxane (D(4)) after exposure to silicones by inhalation and implantation.
(37/517)
We developed a physiologically based pharmacokinetic (PBPK) model to predict the target organ doses of octamethylcyclotetrasiloxane (D(4)) after intravenous (IV), inhalation, or implantation exposures. The model used (14)C-D(4) IV disposition data in rats to estimate tissue distribution coefficients, metabolism, and excretion parameters. We validated the model by comparing the predicted blood and tissues concentrations of D(4) after inhalation to experimental results in both rats and humans. We then used the model to simulate D(4) kinetics after single and/or repeated D(4) exposures in rats and humans. The model predicted bioaccumulation of D(4) in fatty tissues (e.g., breast), especially in women. Because of its high lipid solubility (Log P(oct/water) = 5.1), D(4) persisted in fat with a half life of 11.1 days after inhalation and 18.2 days after breast implant exposure. Metabolism and excretion remained constant with repeated exposures, larger doses, and/or different routes of exposure. The accumulation of D(4) in fatty tissues should play an important role in the risk assessment of D(4) especially in women exposed daily to multiple personal care products and silicone breast implants. (+info)
Typing and subtyping of 83 clinical isolates purified from surgically implanted silicone feeding tubes by random amplified polymorphic DNA amplification.
(38/517)
In this study, 83 clinical isolates purified from biofilms colonizing 18 silicone gastrostomy devices (12 "buttons" and six tubes converted to skin level devices) were selected for subtype characterization utilizing genetic analysis. The tubes, previously used for feeding, remained in place for 3 to 47 months (mean, 20.0 months) in children ranging in age from 6 months to 17 years. Classification of specific microbes using random amplified polymorphic DNA (RAPD) analysis revealed genetic similarities and differences among isolates belonging to the same genus. Both gram-positive and -negative bacteria were investigated, including 2 isolates of Bacillus brevis, 4 isolates of Bacillus licheniformis, 2 isolates of Bacillus pumilus, 3 isolates of Enterococcus durans, 19 isolates of Enterococcus faecalis, 8 isolates of Enterococcus faecium, 2 isolates of Enterococcus hirae, 7 isolates of Escherichia coli, 8 isolates of Lactobacillus plantarum, 19 isolates of Staphylococcus aureus, 2 isolates of Staphylococcus epidermidis, and 7 isolates of Staphylococcus saprophyticus. Amplified DNA fragments (amplicons) provided species-specific fingerprints for comparison by agarose gel electrophoresis. A total of 62 distinct RAPD types were categorized from the five genera studied. Typing analysis suggested cross acquisition of E. coli, E. faecalis, and S. aureus in three patient pairs. Genomic polymorphism detection proved efficient and reliable for classifying bacterial subtypes isolated from biofilms adhering to various portions of commonly employed enteral access tubes. (+info)
High incidence of Pellethane 90A lead malfunction.
(39/517)
AIMS: The long-term performance of Pellethane 80A (P80A) endocardial pacing leads has previously been called into question. We report our experience with an endocardial pacemaker lead with silicone outer and Pellethane 2363-90A (P90) inner insulator. METHODS: Between November 1993 and March 1998, 129 P90A and 189 non-P90A ventricular leads were implanted. Lead malfunction was defined as > or = 25%) deviation in lead impedance or a two-fold reduction in sensing threshold during follow-up. Sensing and capture thresholds and lead impedance were assessed intraoperatively, immediately postoperatively, at 24 h and 6-12 weeks following implant and semiannually thereafter. Adequacy of lead positioning and lead-header interface were documented radiographically in each case. RESULTS: During 204 patient years of follow-up, 10/129 (8%) Oscor RX P90A leads malfunctioned. Average time to malfunction was 14 +/- 11 months. During 166 patient years of follow-up, none of the 189 non-P90A ventricular leads met criteria for malfunction (P < 0.05). There was no difference in patient age, sex, and arrhythmia indication between groups. Sensing problems were overcome with pacemaker reprogramming. CONCLUSION: We conclude that Oscor RX passive fixation ventricular leads with external silicone and inner P90A insulation exhibit an 8%, insulation malfunction rate within 14 +/- 11 months of implant. This is significantly higher than non-P90A leads implanted with identical technique and follow-up regimen. More frequent follow up may be warranted in patients with P90A containing leads. (+info)
Binding of adenosine diphosphate to intact human platelets.
(40/517)
1. Human platelet-rich plasma was incubated at 37 degrees C with [8-14C]ADP and with human serum albumin labelled with 125I. The platelets were rapidly separated by centrifugation through silicone oil. From radioactivity determinations of plasma and platelet pellets the uptake of ADP, without or with break-down products, by the platelets was calculated on the assumption that the 125I radioactivity in the pellet represented trapped plasma. 2. ADP radioactivity was taken up by platelets within 10 sec and increased with time of incubation. The uptake of other nucleotide diphosphates was less initially and increased much more slowly. 3. Radioactivity added as ADP was recovered as ATP to the extent of 60%; as ADP of 30%; and as AMP of 10%. 4. Prostaglandin E1 which inhibited platelet aggregation had no effect on the initial or subsequent uptake or on this distribution of radioactivity. 5. The rate of rise in uptake was much slower when platelets were resuspended in plasma heated to 56 degrees C for 30 min. 6. Unlabelled adenosine inhibited the later, but not the initial, uptake while unlabelled ADP inhibited both. Dipyridamole, which blocks adenosine uptake, prevented the later but not the initial uptake. 7. [alpha-32P]ADP radioactivity was taken up at the earliest sampling time and the extent of uptake did not further increase. 8. Guinea-pig platelets, which do not take up adenosine, took up [8-14C]ADP radioactivity from purine-labelled ADP initially. 9. It was concluded that the initial uptake represented binding of ADP and that the later uptake represented labelled adenosine originating as a break-down product of ADP. 10. A Scatchard plot of ADP uptake indicated more than one type of binding site. There were approximately 88,000 high affinity sites per platelet which had an affinity constant of 5-41 X 10(5) M-1. (+info)