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Biomedical subjects

J Parsons

Publications and source records attributed to J Parsons.

At least 73 records · Page 4Linked to original sources
PubMed1993

Excess concepti compared with number of embryos transferred in in vitro fertilization.

To reduce the risk of multiple pregnancy, most in vitro fertilization programs limit the number of embryos transferred; because monozygotic twinning may occur, it is possible that more concepti are produced than the number of embryos transferred. To quantify the prevalence of this phenomenon, 1820 clinical pregnancies generated from 11,601 in vitro fertilization treatment cycles were reviewed. Two patients conceived four fetuses each after having had three embryos transferred, while one conceived three fetuses after having had two embryos transferred. The overall prevalence rate was, therefore, one in 607 cases. The obstetric details of these three pregnancies are reported.

Journal Article↗
PubMed1993

Imaging of pulmonary vascular disease by intravascular ultrasound.

To assess the ability of intravascular ultrasound (IVUS) to image changes in the pulmonary arterial wall associated with pulmonary hypertension (PHT), 10 subjects requiring diagnostic right and left heart catheterization were studied. In addition to measurements of pulmonary artery pressure and pulmonary vascular resistance and pulmonary angiography, when indicated, all underwent simultaneous IVUS imaging in the pulmonary arterial system using a 20 MHz ultrasound transducer mounted on a 2 mm diameter catheter. Four patients had normal pulmonary artery pressures and 6 had varying degrees of PHT. Satisfactory ultrasound images were obtained in 9 out of the 10 patients. In those with normal pulmonary artery pressures ultrasound showed a thin vessel wall with no distinction between separate layers. In patients with systemic PHT, a three-layered vessel wall was apparent and areas compatible with intimal proliferation were seen. In a patient with pulmonary embolic disease areas consistent with mural thrombus were detected at sites of luminal narrowing on the pulmonary angiogram. IVUS is capable of imaging some of the morphological changes in the wall of the pulmonary artery known to occur in longstanding PHT and may therefore become a useful adjunct to haemodynamic measurements and pulmonary angiography for the in vivo assessment of pulmonary vascular disease.

Adolescent↗
PubMed1993

Complications of transvaginal ultrasound-directed follicle aspiration: a review of 2670 consecutive procedures.

PURPOSE: Complications following transvaginal ultrasound-directed follicle aspiration are rare, making it difficult to assess their true incidence. During a 4-year prospective study the complications arising from a series of 2670 consecutive procedures were monitored. RESULTS: Vaginal hemorrhage occurred in 229 (8.6%) of the cases, with a significant loss (> 100 ml) in 22 (0.8%). Postoperative pelvic infection occurred in 18 (0.6%) of the cases. Hemorrhage from the ovary with hemoperitoneum formation was seen on two occasions and necessitated emergency laparotomy in one instance. A single case of pelvic haematoma formation from a punctured iliac vessel was also recorded; this settled without intervention. Of the 18 cases with infection, 9 were severe with pelvic abscess formation; microbiological examination of the pus from these cases suggests that the most common route of infection in such cases is probably by direct inoculation of vaginal organisms into the peritoneal cavity by the collecting needle. CONCLUSION: The low incidence of pelvic infection questions the value of using prophylactic antibiotics. No increased risk of infection was demonstrated in cases with preexisting peritoneal damage.

Abscess↗
PubMed1993

Traumatic pneumomediastinum in a child secondary to corn chip perforation of the esophagus.

Esophageal perforations, while an infrequent form of trauma in the pediatric population, are of concern because of their life-threatening complications. If not recognized and treated promptly, esophageal injuries can result in mediastinitis and death. An unusual case is presented, describing traumatic esophageal perforation in a child resulting from laceration by an ingested corn chip. A study is reported investigating the rigidity of three types of these popular snack chips. Stress testing and statistical analysis of the resultant measurement data indicated that the three brands of chips were equally rigid. The mean force of compression required to fracture the chips was approximately three pounds, a force great enough to damage the fragile structures of the upper aerodigestive system. Physicians and parents alike should be aware of the possible dangers of this type of snack food to avert the possibility of esophageal injury with its resultant morbidity and potential mortality.

Child↗
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↗
PubMed1992

Biocompatible circuits: an adjunct to non-cardiac extracorporeal cardiopulmonary support.

The utilization of cardiopulmonary bypass systems, for circulatory and/or pulmonary support of patients undergoing non-cardiac procedures, has been previously reported. There is, however, a sub-group of patients for whom total systemic anticoagulation for cardiopulmonary support is extremely undesirable or contraindicated altogether, due to the presenting pathology or procedure to be performed. Clinical and experimental reports have suggested that with the use of heparin-bonded bypass circuits, the amount of heparin required for anticoagulation of the patient may be substantially reduced, or eliminated, safely. This allows the resuscitation and/or support of patients in whom bypass would otherwise be contraindicated. We present our clinical experience with heparin-bonded, biocompatible circuits, for support of patients undergoing non-cardiac procedures. In each case, low-dose or no heparin was administered. The group includes patients with trauma related pulmonary insufficiency, pulmonary embolism, hypothermia, neurosurgery, aortic aneurysm, aortic transection, respiratory distress syndrome, pericardiectomy, and cardiogenic shock.

Adolescent↗
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↗