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Biomedical subjects

D Pretorius

Publications and source records attributed to D Pretorius.

14 recordsLinked to original sources
PubMed2006

Prenatal detection of associated anomalies in fetuses diagnosed with cleft lip with or without cleft palate in utero.

OBJECTIVE: The aim of this study was to determine the prenatal detection rate of associated anomalies in fetuses with a suspected cleft lip with or without cleft palate. METHODS: Fetuses with a suspected cleft lip with or without cleft palate, determined by prenatal ultrasound, were prospectively enrolled. Additional anomalies suspected by ultrasound or genetic testing were recorded. Postnatal outcome was obtained. RESULTS: Forty-five fetuses with a cleft lip with or without cleft palate, diagnosed prenatally with either two-dimensional and/or three-dimensional ultrasound, were studied. Postnatal follow-up revealed that 16 (35.6%) of these 45 fetuses had an additional structural or syndromic abnormality. Of the 37 fetuses with prenatally determined 'isolated' cleft lip with or without cleft palate, eight (21.6%) had an additional malformation identified after delivery. CONCLUSION: In pregnancies complicated by a cleft lip with or without cleft palate, patients should be informed of the risks of associated anomalies, some of which may be undetected prenatally.

Abnormalities, Multiple↗
PubMed2005

Prenatal screening for congenital heart disease using real-time three-dimensional echocardiography and a novel 'sweep volume' acquisition technique.

OBJECTIVES: Conventional prenatal screening for congenital heart disease (CHD) involves a time-consuming and highly operator-dependent acquisition of the four-chamber view and outflow tracts. By acquiring the entire fetal heart instantaneously as a single volume, real-time three-dimensional echocardiography (RT3DE) may facilitate fetal cardiac screening. METHODS: Four reviewers, each experienced with fetal cardiac imaging, blindly and independently evaluated a single cardiac volume from each of 18 fetuses (11 normal, seven with CHD). Two-dimensional echocardiography served as the gold standard. Three-dimensional evaluation of each fetus included a series of volume acquisitions lasting 2-6 s each. A 'sweep volume' technique was developed to fit larger hearts into a single non-gated volume. RESULTS: RT3DE had a high sensitivity for detecting CHD (93%), with only a single case being missed by two observers. Specificity for CHD was low (45%), with a high rate of 'cannot determine' responses and false positive artifacts. CONCLUSIONS: These preliminary results suggest that RT3DE has the potential to function as a screening tool for fetal heart disease. However, artifacts must be recognized and minimized, resolution must improve, and substantial training will be necessary prior to widespread clinical use.

Artifacts↗
PubMed2001

Novel mutations identified using a comprehensive CCR5-denaturing gradient gel electrophoresis assay.

BACKGROUND: Most mutations detected for the gene for CC chemokine receptor 5 (CCR5) are either relatively specific to different population groups or rarely observed in Africans. OBJECTIVES: To develop a comprehensive mutation detection assay for the entire coding region of CCR5 and to identify novel mutations that may play a role in genetic susceptibility to HIV-1 infection, within the diverse South African population. DESIGN: The study cohort consisted of 103 HIV-seropositive patients and 146 HIV-seronegative controls of predominantly African descent. METHODS: A mutation detection assay for the entire coding region of CCR5 was designed; this included amplification of part of the coding region of CCR2. The assay was based on denaturing gradient gel electrophoresis (DGGE) and allowed the complete analysis of samples from 10 individuals per denaturing gel. RESULTS: The use of the CCR5-DGGE assay led to the identification of seven novel and six previously reported mutations. All novel mutations, including a common polymorphism at codon 35, occurred exclusively in non-Caucasians, indicating possible African origin. CONCLUSION: A comprehensive DGGE mutation detection assay has been developed for the entire coding region of CCR5. Application of this assay resulted in the identification of novel CCR5 mutations, which may have a significant effect on the normal functioning of CCR5 and thus contribute to host variability and susceptibility to HIV-1 infection and/or progression to AIDS within this population.

Codon, Nonsense↗
PubMed2000

Three-dimensional multiplanar ultrasound for fetal gender assignment: value of the mid-sagittal plane.

OBJECTIVE: To evaluate the feasibility and accuracy of fetal gender assignment from three-dimensional ultrasound (3D US) data at 10-24 weeks' gestation. METHODS: Three-dimensional ultrasound volume data on 47 fetuses were reviewed and divided into groups: 10-14, 15-18, and 19-24 weeks. Fetal genitalia were studied in axial and sagittal planes for gender assignment, using published criteria. The most valuable plane for assignment was noted. Gender assignment was compared with gender at birth. RESULTS: Gender assignment was possible in 44 of 47 fetuses; 25 assigned male and 19 female. Between 10 and 14 weeks the mid-sagittal plane alone was diagnostic for all fetuses. Accuracy of assignment between 11 and 14 weeks was 100%. Between 15 and 18 and 19 to 24 weeks, male assignment was 100% accurate. Female assignment was 100% accurate between 15 and 18 weeks. Accuracy decreased to 60% in the 19 to 24 week group, however, in two of the five cases in which gender was wrongly assigned to be male, the assignment was prospectively considered doubtful due to poor resolution of volume data. Excluding these two cases, accuracy for female assignment in the 19-24 week group was 100%. CONCLUSION: Using 3D US, gender assignment was possible in 44 of 47 of fetuses, as early as 11 weeks' gestation. In early gestation, 11-14 weeks, accuracy of male and female gender assignment was 100%.

Feasibility Studies↗
PubMed1999

Real-time three-dimensional fetal echocardiography: initial feasibility study.

Real-time three-dimensional echocardiography acquires data as a volume rather than as a series of planar images, thereby obviating cardiac or respiratory gating and limiting artifacts generated by random motion. This study was undertaken to evaluate the feasibility of using real-time three-dimensional echocardiography to evaluate fetal cardiac anatomy and function. Ten human fetuses were evaluated in utero, four of whom had congenital heart disease. Freehand transabdominal scanning was performed on each pregnant woman using a real-time three-dimensional echocardiography system. Four volume clips at 20 volumes/s of duration 1.5 s each were obtained on each fetal heart and stored for off-line analysis. Data were displayed immediately as a series of four simultaneous planes, with the ability for the observer to manipulate the position of each plane within the acquired volume data set. Cardiac motion could be slowed, stopped, or viewed at its original speed. Most structures and views, as well as cardiac function, could be visualized consistently. Abnormal structures could be detected readily. Off-line analysis was rapid and easy. We conclude that fetal real-time three-dimensional echocardiography is a feasible, facile, and rapid new technique.

Echocardiography, Three-Dimensional↗
PubMed1993

Caudal regression versus sirenomelia: sonographic clues.

Seven cases with the pathologic/autopsy diagnosis of caudal regression or sirenomelia in which antenatal sonography had been performed were reviewed. The three patients with caudal regression had similar findings on antenatal sonogram, including normal or increased amniotic fluid, mild dilation or normal urinary systems, nonfused extremities, and sacral agenesis. In the four patients with sirenomelia, common sonographic findings included marked oligohydramnios, suspected renal agenesis, and sacral agenesis. A history of maternal diabetes was elicited in all patients with caudal regression and in none of the patients with sirenomelia. Findings confirm recent articles in pediatric pathology suggesting that caudal regression is a separate entity, distinct from sirenomelia.

Abnormalities, Multiple↗
PubMed1993

Rights to gametes, zygotes and embryos in storage.

In this article the issue of whether one may claim 'ownership' to genetic material and embryos in storage is considered. For this purpose the legal position in some representative jurisdictions, such as the United States of America, France, Australia and Great Britain, is examined. Finally, the present legal situation in South Africa is examined. It is concluded that the extent and nature of the rights to gametes, zygotes and embryos in storage are at present largely uncertain. Court decisions in representative jurisdictions also fail to provide uniform answers. It is concluded that a clear distinction should be made between rights to gametes on the one hand and rights to ygotes or embryos on the other. In the latter, fusion of gametes has occurred and the sperm and eggs are no longer separate entities. It is recommended that the interests of the parties, the storage facility and the embryo can best be protected by a written agreement. This document should contain clear provisions for a considerable change in circumstances, for instance death, divorce or the impossibility of completion of the process.

Australia↗
PubMed1991

Morbidity associated with prenatal disruption of the dividing membrane in twin gestations.

We report eight cases of intrauterine rupture of the dividing membranes in diamniotic twin gestations and the resulting perinatal morbidity and mortality. The poor outcomes associated with these intrauterine amniotic ruptures included fetal and neonatal death secondary to cord entanglement, preterm rupture of the membranes, preterm labor and delivery, and amniotic band syndrome. The overall perinatal mortality rate was 44% (seven of 16), and the mean gestational age at delivery was 29 weeks (range 22-34). Possible etiologies for this intrauterine diamniotic rupture include fetal trauma to the dividing membranes, amniocentesis, infection, and developmental disturbances. A new theory is examined to explain the surviving twin's morbidity associated with intrauterine death of the co-twin. This study suggests that intrauterine rupture of diamniotic twin membranes carries a perinatal mortality consistent with that of true monoamniotic gestations and that, in fact, this entity may be more common than previously thought. Finally, a suspected monoamniotic gestation cannot be ruled out by the historic presence of a dividing membrane on previous ultrasound examination.

Adolescent↗
PubMed1989

Gallbladder function is altered in sickle hemoglobinopathy.

Despite comparable rates of hemolysis, only 50% of patients with sickle hemoglobinopathy (SH) develop pigment gallstones by age 20 yr. Thus, pathogenetic factors, other than hemolysis, may contribute to gallstone formation. In the present study we determined whether gallbladder function, measured by real-time ultrasonography or bile acid metabolism, determined by isotope dilution-mass spectrometry, were altered in adolescents and young adults with SH. Compared with healthy controls, SH subjects had larger fasting (27 +/- 16 vs. 15 +/- 5 ml, p less than 0.02), and residual (8 +/- 6 vs. 4 +/- 2 ml, p less than 0.03) volumes of the gallbladder, but similar rates of emptying (0.029 +/- 0.016 vs. 0.034 +/- 0.029 min-1) and percentage of fasting volume emptied (71% +/- 13% vs. 72% +/- 14%). In SH subjects, the volume and emptying of the gallbladder were similar between those with and without gallstones. Some SH subjects had stasis of bile within the gallbladder, as demonstrated by isotopic disequilibrium between the circulating bile acid pool and bile stored in the gallbladder. Subjects with SH with gallstones tended to have smaller bile acid pools than SH subjects without gallstones (81 +/- 11 vs 163 +/- 91 mumol/kg, p = 0.051). We conclude that adolescents and young adults with SH have enlarged gallbladders that retain an increased postprandial volume of bile. Bile retention within the gallbladder may lead to stasis and contribute to the pathogenesis of pigment gallstones.

Adolescent↗
PubMedDate not supplied

The role of nuclear scanning in head and neck surgery.

A number of procedures in nuclear medicine are available to assist the surgeon in evaluating pathologic conditions of the head and neck. Gallium-67 citrate scanning is occasionally useful in determining the extent of head and neck tumors but rarely can it detect an occult tumor and it cannot distinguish between an infection and a tumor. Technetium-99m pertechnetate can be used to evaluate diseases of the salivary glands including 123 and technetium-99m pertechnetate are commonly used to obtain images of the thyroid, but some malignant thyroid nodules will accumulate technetium-99m pertechnetate and the suspicious character of the nodule may be only appreciated by iodine scanning. The use of iodine 131 is generally limited to the detection of a substernal thyroid, therapeutic thyroid ablation, and the treatment of hyperthyroidism and thyroid cancer. Bone scanning has been used experimentally to evaluate the healing of mandibular bone grafts and to detect local extension of primary head and neck tumors to skull and facial bones.

Abscess↗