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Biomedical subjects

S R Stephens

Publications and source records attributed to S R Stephens.

16 recordsLinked to original sources
PubMed2002

Female sex selection using clomiphene citrate and albumin separation of human sperm.

BACKGROUND: This study was undertaken to assess whether the use of clomiphene citrate in conjunction with albumin-separated sperm would alter the sex ratio (expressed as the proportion of males) towards females and, if so, whether this skewing was due solely to the induction of ovulation. METHODS: The sex ratios of 184 single and 42 twin births at five assisted reproduction biology clinics were determined. The normal approximation to the binomial distribution was used to determine significant differences between these sex ratios and the established sex ratios for single, twin and combined (single and twin) non- and ovulation-induced births. RESULTS: The non-ovulation-induced sex ratios for singletons (51.4%) and twins (50.2%) were greater than the treatment singleton (27.7%; P < 0.001) and twin (33.3%; P < 0.01) sex ratios respectively. Correspondingly, the non-induced sex ratio for combined births (51.4%) was greater than the treatment sex ratio (28.8%; P < 0.001). The previously established induced singleton and twin sex ratios (48.1%) were lower than the non-induced sex ratio (51.4%), but higher than the treatment singleton (27.7%; P < 0.001) or twin (33.3%; P < 0.03) sex ratios. The ovulation-induced combined ratio (48.1%) was less than the non-induced combined (51.4%) sex ratio, although greater than the treatment combined sex ratio (28.8%; P < 0.001). CONCLUSION: Clomiphene citrate in conjunction with albumin-separated sperm decreased the sex ratio; a reduction that was not exclusively due to induction of ovulation.

Cell Separation↗
PubMed2001

Towards the characterisation of heavy metals in dredged canal sediments and an appreciation of 'availability': two examples from the UK.

Canal sediments can act as sinks for a wide range of contaminants including heavy metals from various sources (e.g. industrial and waste water discharges). Dredging of canals is required to maintain navigational depth and prevent flooding. The sediments removed from canals are often disposed of to land, being deposited either straight on to the banks of the canal or, in recent years, in licensed disposal sites. The aim of this work was to investigate the nature of dredged sediment-derived soils and the heavy metals present in them. Two disposal sites in the United Kingdom (UK) were investigated and soil samples taken. A variety of analytical techniques were used, including Aqua regia digestion and sequential extraction, in order to assess the concentrations and associations of metals present. Diethylene triaminepenta-acetic acid extracts, performed to illustrate plant-available metal concentrations, reveal that up to 40% of the total extracted metals were in an 'available' form. Variations in metal concentrations with depth in the soil cores show a significant correlation with total organic carbon content.

Biological Availability↗
PubMed2001

Changes in the leachability of metals from dredged canal sediments during drying and oxidation.

The behaviour of metals in canal sediments after their disposal to land has important implications for the environmental management of canal dredgings. The leaching behaviour of trace metals was investigated in a laboratory-based experiment using sediment from a canal in the UK (139 mg Zn kg-1dry sediment, 1.1 mg Cd, kg-1dry sediment 31.5 mg Cr kg-1dry sediment, 20.6 mg Cu kg-1dry sediment 48.4 mg Ni kg-1dry sediment, 43.4 mg Pb kg-1dry sediment and 7.6 mg As kg-1dry sediment). The sediment was allowed to dry. Cores (10 cm long) of the drying canal sediment were taken over a period of 12 weeks. A simple water extraction procedure was used to investigate changes in metal leachability at varying depths through the cores. Metal leachability increased over the first five weeks of drying and then subsequently decreased between weeks five and twelve, (e.g. Cd increased from approximately 0.006 to 0.018 mg/kgsediment then decreased to approximately 0.006 mg/kgsediment, Zn increased from approximately 1.5 to 3 mg/kgsediment and then decreased to approximately 1.5 mg/kgsediment). These results were combined with sulphide/sulphate ratios, which showed a decrease as the sediment dried (e.g. at 2-4 cm depth from approximately 1 to 0.49), and BCR sequential extraction data. Most metals (except Cd and As) showed a redistribution from the residual phase into more mobile phases as the sediment dried and oxidised. Metal leachability was strongly correlated with the sulphide/sulphate ratio with leachability normally increasing with decreasing sulphide/sulphate ratio. The combined results were used to infer the likely behaviour of dredged material upon disposal to land.

Environmental Monitoring↗
PubMed1992

Analysis of tissue margins of cone biopsy specimens obtained with "cold knife," CO2 and Nd:YAG lasers and a radiofrequency surgical unit.

Analysis of the tissue margins of cone biopsy specimens obtained from 40 patients showed varying degrees of thermal and mechanical artifact at the tissue margins. The least artifact was seen in the tissue margins of specimens obtained with the scalpel ("cold knife"). The amount of thermal damage to biopsies obtained via lasers and the radiofrequency unit varied with the instrument employed. However, the quality of the tissue margins of specimens obtained using a radiofrequency surgical unit equipped with a needle electrode on a "pure cut" setting approached the quality of those obtained with the cold knife in their lack of thermal and mechanical artifact.

Biopsy, Needle↗
PubMed1968

Myoma of the uterus.

Explore the source record for details and available documents.

Diagnosis, Differential↗
PubMedDate not supplied

Arthroscopic acromioplasty: a 6- to 10-year follow-up.

Arthroscopic acromioplasty has become a common procedure for the treatment of chronic impingement syndrome. Short-term studies have consistently shown good results; however, long-term data have not previously been reported in the literature. Of 102 consecutive patients undergoing arthroscopic acromioplasty at our institution from 1984 to 1988, 82 patients (83 shoulders) were available for evaluation. The patients were reviewed after a mean of 8 years, 5 months from their original surgery. There were 16 failures (19%) with unsatisfactory results following surgery; 13 patients (15%) required further surgery to relieve persistent pain. Thirty-three percent of all patients previously involved in sports were unable to return to overhead and throwing sports due to pain and lack of power with throwing. Overall, 81% of patients in our series had good to excellent results after 6 to 10 years. To optimize the indications for the procedure, other causes of impingement, such as occult instability and degenerative joint disease, should be ruled out. Throwers may have difficulty returning to their sport at the same level of intensity, and should be addressed independently.

Acromion↗
PubMedDate not supplied

Physostigmine reversal of sedation in parturients.

Parturients in whom meperidine HCl, propiomazine HCl, and scopolamine were used for analgesia and amnesia in labor and delivery were studied to determine the efficacy and safety of physostigmine reversal after delivery. Of a total of 120 patients, 108 received physostigmine salicylate at the completion of episiotomy closure, awakening in an average of 7.5 minutes compared with 137.8 in 12 controls. Physostigmine appears to be a safe, rapidly effective agent for reversing the prolonged somnolence of this sedation regimen.

Adult↗