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Biomedical subjects

A Staples

Publications and source records attributed to A Staples.

13 recordsLinked to original sources
PubMed1998

Pregnancies complicated by retained placenta: sex ratio and relation to pre-eclampsia.

Pre-eclampsia and placenta accreta have opposite histological features of placentation. This study set out to test the hypotheses that the sex ratios in these two pregnancy complications are opposite and that these conditions are mutually exclusive. A population-based database covering all deliveries in South Australia between 1986 and 1995 and the hospital-based obstetric database of the Adelaide Women's and Children's Hospital, covering 8549 births between 1993 and 1995, were used to ascertain the sex ratios in singleton pregnancies and the sex ratios in those pregnancies in which there was retained placenta, hypertension in pregnancy, or pre-eclampsia. The likelihood of independence of occurrence or mutual exclusivity of retained placenta and hypertension in pregnancy or pre-eclampsia were also examined. The male:female sex ratio in the South Australian population was 1.077. In pregnancies with hypertension in pregnancy it was 1.165 (P<0.001) and in pregnancies with retained placenta it was 0.883 (P<0.0001). There was a trend to an increased sex ratio in pre-eclamptic pregnancy (1.248 in primigravid and 1.092 in multigravid women) but there was insufficient power to detect significance (P=0.207 and 0.470, respectively). Neither hypertension in pregnancy nor pre-eclampsia were mutually exclusive of placenta accreta: hypertensive disorders of pregnancy and placenta accreta occurred independently of each other. Our findings suggest that sex-linked antigens are unlikely to influence maternofetal interactions consistently to give rise to one but not the other pregnancy complication.

Adult↗
PubMed1997

Electron microscopy and morphometry enhances differentiation of epidermolysis bullosa subtypes. With normal values for 24 parameters in skin.

Electron microscopy combined with morphometry was used to establish values for 24 parameters in normal skin. These results were compared with those similarly obtained from samples of epidermolysis bullosa with a view to facilitating classification of the disease. Six of the eight subtypes of epidermolysis bullosa investigated could be differentiated. Four subtypes showed values for structural components in intact skin which were outside the normal range: (1) epidermolysis bullosa simplex generalisata gravis (hemidesmosomes); (2) epidermolysis bullosa dystrophica Pasini and (3) Cockayne-Touraine (anchoring fibrils); and (4) epidermolysis bullosa acquisita (anchoring fibrils, hemidesmosomes, and lamina lucida and lamina densa aspects of the dermoepidermal junction). Two subtypes revealed specific features which could be assessed qualitatively: distinctive, circumscribed, clumped tonofilament bodies were present in basal keratinocytes from epidermolysis bullosa herpetiformis Dowling-Meara and thick (30 nm diameter) cross-striated anchoring fibrils were absent in epidermolysis bullosa dystrophica generalisata gravis. Epidermolysis bullosa simplex Köbner and Weber-Cockayne forms could not be distinguished.

Adolescent↗
PubMed1996

Dynamic mutation loci: allele distributions in different populations.

To assess the relative contributions of trans-acting factors (replication and repair functions) and cis-acting elements (repeat and flanking DNA composition) to the mechanism of trinucleotide repeat sequence mutation we have analysed the distribution of copy number polymorphisms at 12 loci associated with dynamic mutations in 15 populations of different ethnic origins. Genome wide instability of repeats in a particular population would be evidence of trans-acting factor instigation of the mutation process, whereas instability at a particular locus (perhaps even in several populations) would be evidence that the composition of the particular locus was the most significant factor contributing to mutation. The FRA16A locus is highly polymorphic in only the European population. Some other loci exhibit distinct distributions of alleles between different populations. Therefore sequences in the vicinity of the repeat -- the cis component of a particular locus -- appear(s) to be more important in the mutation mechanism than sporadic genome-wide instability induced by trans-acting factors such as the DNA mismatch repair enzymes.

Alleles↗
PubMed1995

Observer reliability in assessing placental maturity by histology.

AIMS: To evaluate the ability of five experienced perinatal pathologists to assess placental maturity reliably by histology. METHODS: Twenty four haematoxylin and eosin slides, six each from placentas of 27, 31, 35, and 39 weeks' gestation, were circulated to five pathologists on three separate occasions. The slides were labelled with the correct or incorrect gestational ages. RESULTS: The mean absolute error over all 360 readings was 2.72 weeks. Only 54% of the slides were assessed within two weeks of the correct gestation. Pathologist tended to overestimate younger gestations and underestimate older gestations. Two, and possibly three, pathologist were influenced by the gestational age state on the label. One pathologist, who did not appear to be influenced by the label, was more accurate in diagnosing gestation of the placentas than other colleagues. CONCLUSIONS: Experienced pathologists can have difficulty in assessing the villous maturity of placentas by histology. They can also be influenced by clinical information provided, such as gestational age. Other observer reliability studies must address the issue of the influence of labelled information on observer variation. A difference in maturation would have to be of a six week magnitude to have a chance of being detected by current methods. This may limit the value of the histological diagnosis of placental dysmaturity as a surrogate marker for uteroplacental ischaemia.

Analysis of Variance↗
PubMed1994

Haplotype analysis at the FRAXA locus in the Japanese population.

Fragile X syndrome, one of the most common human genetic diseases, is characterized by a unique genetic mechanism which involves dynamic mutation in a heritable unstable DNA sequence, a p(CCG)n repeat, in the FRAXA locus. It has recently been suggested that a few founder chromosomes are responsible for most fragile X mutations in the Caucasian population. In order to investigate the origin of the fragile X mutations in the Japanese population, we analyzed haplotypes of the FRAXA locus in 40 unrelated fragile X chromosomes and 142 normal X chromosomes in Japanese males, by using two polymorphic AC repeats, FRAXAC1 and FRAXAC2, which flank the fragile site. This analysis provided evidence for founder fragile X chromosomes in the Japanese population, similar to that in Caucasians, although different haplotypes are involved. The distribution of normal allele size of the p(CCG)n repeat among the X chromosomes in the Japanese population is very similar to that reported for Caucasians, except that the most frequent copy number (n = 28) is one copy less than that in Caucasians and that there is an additional peak at 35 copies. There is significant correlation between FRAXAC alleles and the p(CCG)n repeat copy number in non-fragile X chromosomes, however, alleles with more than 31 copies of the p(CCG)n repeat do not segregate with either of the fragile X common FRAXAC haplotypes.

Asian People↗
PubMed1993

Glomerular dimensions in children under 16 years of age.

Glomerular area, perimeter, and mean maximum glomerular diameter were assessed in post-mortem kidney tissue from 114 children who died suddenly in accidents and who were considered to have been previously healthy. One hundred glomeruli were measured from each case using a computer-based measurement system. Regression analysis was used to analyse glomerular size with respect to age, body weight, height, and body mass index. The estimated mean glomerular area for newborns was 7934 microns 2 (SE 314), increasing 8 per cent per year to 18,219 microns 2 at 15 years of age. The estimated mean maximum glomerular diameter increased from 112 microns (SE 1.9 microns) for newborns, approximately 3.6 microns per year to reach 167 microns at age 15. Glomerular size correlated better with age than with height, weight, or body mass index, and glomeruli in the inner cortex were significantly larger than those in the middle and outer cortex. Glomerular size was significantly greater in female children than in the male children over the age range examined.

Adolescent↗
PubMed1993

Anthropometric measurements in the second trimester fetus.

Normal anthropometric measurements, of accepted value for clinicians and pathologists in the assessment of the dysmorphic neonate, have not in the past been available for the second trimester fetus, in which dysmorphic features are often more subtle and objective measurements most needed. In order to establish these values 19 anthropometric measurements, comparable to those published for the larger fetus and neonate, were recorded at autopsy on each of 260 overtly normal non-macerate singleton fetuses between 13 and 26 weeks gestation. Regression lines for each parameter, and growth ratios of potential value for description and assessment of dysmorphic features, were derived. The sex ratio was 1.27 and as there was no statistically significant sex difference for any of the 19 measurements chosen, the data was subsequently pooled. There were linear correlations between gestational age and each growth parameter, all but three exceeding 0.90. The linear correlations between pairs of growth parameter were higher than the correlations between gestational age and individual growth parameters. This suggests that growth parameter pairs, expressed as a ratio, are less affected by errors in gestational age estimation. Ratios enabling the dysmorphologist to more objectively assess common observations such as abnormalities of head shape, relationship between limb and trunk length and gross proportional relationships between major body segments were derived. Collected measurements were compared with established ultrasound reference ranges. While reference ranges for biparietal diameter and head circumference showed close concordance with those derived from ultrasound measurements, the abdominal circumference was consistently lower than that measured by ultrasound possibly because of differing trunk positions in utero compared with after death. The graphs and ratios derived in this study can be rapidly applied to confirm visual impressions at clinical examination and at autopsy.

Anthropometry↗
PubMed1993

Acceptance of mementos of fetal and perinatal loss in a south Australian population.

A package of mementos of a fetal or perinatal loss has been shown to help with the grieving process. The level of acceptance and the factors influencing acceptance of these mementos in a South Australian population was examined over a 27-month period. Data were available on 447 women and the acceptance rate was 79.6%. Major influences on the acceptance of mementos were maternal age and gestational age. Mothers in the 20-30 year age group were more likely to accept mementos than younger and older mothers. This age-related effect was more noticeable among genetic terminations and neonatal deaths than among spontaneous abortions or stillbirths. Memento acceptance of miscarriages and stillbirths over 20 weeks' gestation was significantly greater than for younger gestation. These findings may have an impact on the psychosocial management of perinatal loss. The high level of acceptance of these mementos is encouraging and vindicates our current practice which we recommend to others involved in the management of perinatal loss.

Australia↗
PubMed1993

Observer reliability in assessing villitis of unknown aetiology.

AIMS: To evaluate observer variation in diagnosis of villitis of unknown aetiology. METHODS: Fifty haematoxylin and eosin stained sections were circulated to three pathologists who were asked to assess if villitis was present. These slides, with an additional 20, were recirculated and reassessed by the same pathologists. RESULTS: Intra-observer agreement was 84.7% (range 74--92%) and interobserver agreement was 81%. A conjoint review by the three pathologists revealed that sources of differences included the overlooking of isolated single or small numbers of affected villi, the difficulty in assessing stromal cellularity close to infarcted parenchyma, and apparent stromal hypercellularity in immature villi. CONCLUSIONS: Experienced pathologists can show a significant interobserver variation in assessing villitis of unknown aetiology. Future studies on villitis of unknown aetiology should address the problem of observer reproducibility of diagnosis.

Chorionic Villi↗
PubMed1992

Evidence of founder chromosomes in fragile X syndrome.

The mutation responsible for fragile X syndrome and myotonic dystrophy involves the amplification of a simple trinucleotide repeat sequence, which increases in successive generations of affected pedigrees accounting for increasing penetrance of both disorders. This common molecular basis suggests that the two diseases may share other genetic features, but whereas myotonic dystrophy exhibits a significant founder chromosome effect, fragile X syndrome apparently has a very high mutation frequency. By haplotype analysis of microsatellite markers which flank the fragile X unstable element, we have uncovered evidence of founder chromosomes of the fragile X 'mutation'. Disorders caused by heritable unstable elements may therefore exhibit common genetic properties including anticipation and founder chromosomes.

Base Sequence↗