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Biomedical subjects

J Parsons

Publications and source records attributed to J Parsons.

At least 19 recordsLinked to original sources
PubMed1992

Determinants of hemodynamic results of balloon dilation of aortic recoarctation.

Between October 1982 and May 1990, balloon dilation of aortic recoarctation was attempted in 27 patients. In 1 case dilation was not performed owing to suspected aortic perforation. The remaining 26 patients had 30 procedures. The age at the first dilation ranged between 2.6 months and 18.3 years. After dilation, systolic gradient decreased from 49 +/- 17 mm Hg to 20 +/- 17 mm Hg (p less than 0.001). A reduction of gradient to less than or equal to 20 mm Hg occurred after the first dilation in 17 of 26 (65%) patients. Residual gradients between 25 and 80 mm Hg were present in the remaining 9 patients. During follow-up of 2 months to 6.7 years, 5 of 17 patients with a good initial result developed further recoarctation (2 had successful redilation, 2 had reoperation, and 1 is awaiting repeat dilation). Of 9 patients with gradients greater than 20 mm Hg after the first dilation, 1 had successful redilation and 3 had reoperation. The remaining 5 patients are being managed conservatively. 2 patients developed aneurysms after dilation (1 immediately and the other at 2 months). In all, 15 patients (58%) had a good, and 11 (42%) a poor late hemodynamic result. Aortic diameters at different levels of the aortic arch and at the reconstructed isthmus (normalized to the aorta at the level of the diaphragm) were significantly higher in the group with a good late result than in that with a poor one. Balloon/aortic diameter ratio at diaphragm level also had a significant influence on the late results.

Adolescent↗
PubMed1992

The effects of lignocaine on human sperm motility.

OBJECTIVE: The purpose of this study was to assess the motility of human sperm incubated with various concentrations of lignocaine. METHODS: Eleven semen samples with a sperm density greater than or equal to 20 x 10(6) ml and progressive motility greater than or equal to 40% were prepared using a swim-up technique. Aliquots from each sample were incubated for 4 hr under capacitating conditions with lignocaine concentrations of 100, 10, 1, and 0.1 microgram/ml and without additional lignocaine as a control. Digital computerized motion analysis was performed on all samples at 1, 2, and 4 hr after the addition of lignocaine. RESULTS: After 2 hr of incubation a significant (P less than 0.05) increase in the percentage of sperm with a curvilinear velocity greater than 100 microns/sec was observed in those samples incubated with 100 micrograms/ml lignocaine. This stimulatory effect was no longer apparent after a further 2 hr of incubation. No other significant changes were identified in any of the motility parameters examined. CONCLUSIONS: No adverse effects on human sperm motility were identified during incubation with low concentrations of lignocaine. A transient stimulatory effect was observed at a lignocaine concentration of 100 micrograms/ml.

Humans↗
PubMed1992

A prospective randomized study comparing aspiration only with aspiration and flushing for transvaginal ultrasound-directed oocyte recovery.

OBJECTIVE: To compare aspiration only with aspiration and flushing of ovarian follicles during transvaginal ultrasound (US)-directed oocyte recovery. DESIGN: Prospective randomized study. PATIENTS: One hundred patients who were undergoing an in vitro fertilization (IVF) treatment cycle. INTERVENTIONS: All patients underwent pituitary desensitization before the administration of gonadotropins. Monitoring of ovarian stimulation and the criteria for the administration of human chorionic gonadotropin were similar in both groups. In patients in whom aspiration alone was used, each follicle was aspirated until it was empty. The US probe was then rotated until every drop of follicular fluid had been aspirated before the next follicle was aspirated and the procedure repeated. For patients who had aspiration and flushing, each follicle was aspirated and then flushed up to a maximum of six times before moving to the next follicle. In both groups, all follicles greater than 10 mm were aspirated. RESULTS: The indication for IVF and mean age of the patients were comparable in the two groups. There were no significant differences between the aspiration and the aspiration and flushing groups in terms of the number of oocytes retrieved (11 versus 9), the oocyte recovery rates (77.5% versus 77.0%), the fertilization rates (55.6% versus 60.0%), the number of embryos transferred (2 versus 2), or the number of clinical pregnancies (12 versus 13). The time taken for oocyte recovery was significantly shorter (15 versus 30 minutes, P less than 0.00001), and the dose of pethidine required significantly less (50 mg versus 100 mg, P less than 0.00001) in the aspiration only group. CONCLUSIONS: Aspiration alone produces comparable oocyte recovery rates as aspiration and flushing while significantly reducing the length of the procedure and the dose of analgesia required. Aspiration alone suffices for virtually all cases during transvaginal US-directed oocyte recovery.

Adult↗
PubMed1992

Secondary structure analysis identifies a putative mouse protein demonstrating similarity to the repeat units found in CDC4, the G protein beta subunits and related proteins.

The predicted protein product of an anonymous clone isolated from a cDNA library prepared from 12 day post coitum (p.c) embryonic mouse heart tissue demonstrated the same segmental repeats previously identified in the cell division control protein, CDC4 and the G protein beta 1 subunit. A search of the protein database subsequently identified three other classes of protein containing the repeat. Secondary structure analyses performed on the repeat sequences revealed a high degree of conservation suggesting that the repeat motif performs a specific function in a diverse range of proteins.

Amino Acid Sequence↗
PubMed1991

An evaluation of CAST: a Computer-Aided Speechreading Training program.

This study assessed the effectiveness of CAST (Computer-Aided Speechreading Training program). Two groups of 8 normal-hearing adults completed a pretraining visual speech perception test protocol that consisted of a Visual-Consonant Recognition Test, a test of Sentence Understanding Without Context, a test of Sentence Understanding With Context, and a semiautomated modified Continuous Discourse Tracking activity available with CAST. One group completed the CAST program. A posttraining test protocol was administered to the subjects 2 weeks following the maximum time provided to complete the training program (i.e., 10 weeks). Independent t tests revealed no differences between the control group and the experimental group in the percentage improvement score obtained on the following measures: viseme recognition score, Sentence Understanding Without Context (key word and total word recognition scores), and Sentence Understanding With Context (key word recognition score). Significant differences between the groups were found for the total word recognition score on the Sentence Understanding With Context test and the CAST modified Continuous Discourse Tracking activity. The results indicate that CAST was most effective in developing aspects of synthetic visual speech perception skills.

Adult↗
PubMed1991

The optimum dose and mode of administration of luteinizing hormone releasing hormone analogue in in-vitro fertilization: a comparison of three regimens.

Three regimens for administration of the luteinizing hormone releasing hormone analogue (LHRHa), buserelin, were compared in terms of pituitary down-regulation prior to ovarian stimulation for in-vitro fertilization (IVF). Thirty-three patients who had failed to conceive in previous IVF cycles were randomly divided into three groups. Patients in Group I (n = 11) received intranasal (i.n.) buserelin 200 micrograms four hourly for 21 days; patients in Group II (n = 11) received subcutaneous (s.c.) buserelin 500 micrograms twice a day for 7 days, followed by 500 micrograms daily for 14 days; patients in group III (n = 11) received (s.c.) buserelin 500 micrograms three times a day for 7 days. In all three groups administration of buserelin was continued until serum oestradiol levels were less than 100 pmol/l, at which time human menopausal gonadotrophin (HMG) was commenced. All the patients achieved pituitary down-regulation after seven days of treatment with buserelin, except for four patients who developed ovarian cysts and two with polycystic ovarian disease. The total dose of HMG used and the ongoing pregnancy rate were not significantly different between the three groups. A much higher proportion of patients in Group I developed side-effects and found their treatment disruptive to their life-style. Our results suggest that patient variables (e.g. polycystic ovaries, ovarian cysts) rather than the dose and mode of administration of buserelin, are the major determinant of the length of time needed for pituitary down-regulation. The s.c. route is preferable and the smallest dose of buserelin that will produce pituitary down-regulation should be used.

Adult↗
PubMed1990

Ultrasound directed follicle aspiration for oocyte collection using the perurethral technique.

Our experience in 242 consecutive ultrasound directed follicle aspirations using the perurethral technique is reported. The mean number of follicles punctured per patient was 9.6 (range 20 to 35), resulting in a mean oocyte yield of 6.1 (range 0 to 31) per patient. It was necessary to change to another ultrasound directed route in 20 patients, and we failed to retrieve oocytes in a further 6 patients. There were no serious complications. The fertilization and cleavage rates were 68% and 91%, respectively. Embryo transfer was performed in 178 cases, resulting in 39 clinical pregnancies (21.9%). Ultrasound directed follicle aspiration by the perurethral route is an efficient way of collecting oocytes and is acceptable to patients. There is no need for general anaesthesia, so this technique is well suited to in vitro fertilization programs based on outpatient procedures.

Biopsy, Needle↗
PubMed1990

Surgical techniques of oocyte collection and embryo transfer.

In the decade since the birth of the first child conceived as a result of in vitro fertilization and embryo transfer much has been achieved in the field of assisted conception. Although in vitro fertilization (IVF) was successful first for the treatment of tubal disease, the indications for its use have now widened to include unexplained infertility, oligozoospermia, endometriosis and infertility due to immunological disorders. Gamete intrafallopian transfer (GIFT) and zygote intrafallopian transfer (ZIFT) are now used commonly for the treatment of couples where the woman has patent fallopian tubes. The huge increase in the demand for therapy using these techniques of assisted conception places considerable strain on the finances available for health care, and has led some to question the wisdom of such use of limited resources. To reduce the cost of treatment, and because repeated IVF-ET attempts may be necessary before achieving pregnancy, the initial laparoscopic approach for oocyte recovery has been largely replaced by ultrasound-guided techniques. Non-surgical embryo transfer techniques have changed little since originally described. However, where the tubes are patent, one-cell zygotes or cleavage stage embryos may be transferred into the fallopian tube (ZIFT and tubal embryo stage transfer respectively). On the other hand if the tubes are blocked, surgical embryo transfer (SET) may be performed. Most recently, some success has been achieved following the transfer of embryos into the fallopian tube by the technique of retrograde fallopian tube catheterisation.

Biopsy, Needle↗
PubMed1990

The perurethral technique for ultrasound directed follicle aspiration in an in-vitro fertilization and embryo transfer programme: a report of 636 patient cycles.

The data from 636 patient cycles from an outpatient-based in-vitro fertilization and embryo transfer programme are presented. Between 1984 and 1988, 545 women (86%) underwent ultrasound directed follicle aspiration (UDFA) exclusively by the perurethral route. The mean follicle aspiration rate was 93%, and the mean number of oocytes per procedure was 5.8. The complication rate was 6%, but none was major. From July 1985 the clinical pregnancy rate per UDFA was 17% and per embryo transfer 21%. The perurethral approach was used in combination with another UDFA route in 91 women (14%) but the need to change route decreased with increasing operator experience. Perurethral UDFA is an efficient and safe method for harvesting oocytes.

Female↗