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Biomedical subjects

B M Byrne

Publications and source records attributed to B M Byrne.

At least 19 recordsLinked to original sources
PubMed2007

Free fetal DNA is not increased before 20 weeks in intrauterine growth restriction or pre-eclampsia.

BACKGROUND: The aim of this study was to quantify maternal plasma fetal DNA and total DNA in early pregnancy in intrauterine growth restriction (IUGR) or pre-eclampsia (PET). METHODS: A nested case control study was carried out in a University Teaching Hospital. Plasma samples were obtained from 1993 women before 20 weeks of gestation. Pregnancies complicated by IUGR or PET were identified and compared to controls. DNA was extracted and real-time quantitative PCR applied for the SRY and beta-actin genes. IUGR or PET groups were compared to controls using the chi(2) and Wilcoxon rank sum tests. RESULTS: SRY was detected in 86% of IUGR (31/36), 94% of PET (15/16) and 78% of controls (56/72). The median SRY was similar in women with IUGR (28 GE/mL) or PET (30.5 GE/mL) and controls (27.5 GE/mL). beta-actin was increased in the IUGR group (3975 GE/mL) compared to controls (1835 GE/mL) (p = 0.045). Cigarette consumption was greater in the IUGR group compared to controls (p = 0.004). CONCLUSIONS: Fetal DNA quantitation in maternal plasma before 20 weeks is not a useful predictor of IUGR or PET. beta-actin levels were elevated before 20 weeks in women with IUGR and may be a marker of maternal susceptibility to this condition.

Actins↗
PubMed2000

Obstetric and neonatal outcome of babies weighing more than 4.5 kg: an analysis by parity.

OBJECTIVES: To analyse by parity the obstetric and neonatal outcome of babies delivered weighing more than 4.5 kg. METHODS: All deliveries resulting in a baby weighing more than 4.5 kg, in the 5 years from 1991 to 1995, were identified using a computerised database. The following variables confined to singleton, cephalic pregnancies were recorded: mode of delivery, duration of labour, incidence of shoulder dystocia and admission to the neonatal centre. Outcome measures in primigravidae and multigravidae were compared using the Epi Info package (WHO, Version 6.0b January 1997). RESULTS: There were 32,834 deliveries over the study period and 828 (2.5%) weighed more than 4.5 kg. Birthweight more than 4.5 kg occurred in 1.6% (n=198) of primigravidae and 3.1% (n=630) of multigravidae (P<0.05). Primigravidae had a higher risk of prolonged labour (27.7% vs. 4.9%), operative vaginal delivery (32% vs.9%) and emergency caesarean section (24.2% vs. 5.7%) compared to multigravidae. When delivering a macrosomic baby, primigravidae had a higher incidence of prolonged labour (27% vs. 7.9%), operative vaginal delivery (32% vs.25%) and emergency caesarean section (24.2% vs. 5.7%) compared to normal weight babies. The incidence of shoulder dystocia and elective caesarean section were similar in both primigravidae and multigravidae. CONCLUSIONS: Macrosomic infants have an increased incidence of prolonged labour, operative vaginal delivery and emergency caesarean section compared with normal weight babies and these complications are more pronounced in primigravidae compared to multigravidae. Shoulder dystocia occurs with equal frequency in primigravidae and multigravidae. The poor antenatal predictability of macrosomia, the high rate of vaginal delivery and the low incidence of shoulder dystocia would not support the use of elective caesarean section for delivery of the macrosomic infant either in primigravidae or multigravidae.

Birth Weight↗
PubMed2000

Antenatal detection of abnormal liver function tests - a marker for poor perinatal outcome.

The purpose of this study was to examine (a) the incidence of liver disease diagnosed in our antenatal population, (b) the diagnostic value of initial symptoms and liver function tests (LFTs), (c) the adequacy of investigation and management of the liver disorder and (d) the obstetric and neonatal outcome in this group of patients. Women with abnormal LFTs that delivered at our hospital over a 2-year period were identified from computerised hospital records and data was obtained from chart review. Forty-six out of a total of 13 181 (0.35%) women had liver disease diagnosed in pregnancy: Diagnoses included intrahepatic cholestasis of pregnancy (13), pre-eclampsia and the HELLP syndrome (eight), acute fatty liver of pregnancy (three), hyperemesis gravidarum (one), hepatitis C (13), B (four) and hepatitis A (one), cholelithiasis (two) and hepatitis of unknown aetiology (one). Symptoms at presentation were more predictive of the final diagnosis than the initial LFT profile. Investigation of the liver disorder was incomplete in 50% of cases. One mother required intensive care for 6 weeks postpartum and three others had significant postpartum haemorrhage. There was one neonatal death and 24 neonates were admitted to the special care baby unit. Eighteen women attended for their postnatal check up at 6 weeks. Eight of these women were referred to a hepatologist. Detection of liver disease in pregnancy identifies a group at risk of poor neonatal and maternal outcome. Structured guidelines should be implemented in obstetric units to facilitate appropriate investigation, treatment and referral patterns for these women.

Journal Article↗
PubMed1999

Prenatal diagnosis of lethal fetal malformation in Irish obstetric practice.

The diagnosis of lethal fetal malformation prenatally has profound implications for the pregnancy, the expectant couple and the medical care provided. The aim of this study was to investigate these implications and the medical factors pertaining to prenatal diagnosis of lethal fetal abnormality in current obstetric practice in Ireland. Data was collected prospectively from all cases of lethal fetal malformation diagnosed at the Fetal Medicine Unit, University College Hospital Galway from December 1997 to June 1998 inclusive. Diagnosis was made on the basis of ultrasound findings and invasive procedures (amniocentesis and chorionic villus sampling). Thirteen cases of lethal fetal abnormality were diagnosed: Edward's syndrome, Patau's syndrome, bilateral multicystic renal dysplasia, Potters sequence, hypoplastic left heart, anencephaly with craniorrhachischisis, lethal osteogenesis imperfecta and non-immune hydrops. Intrauterine death occurred in four cases. Four women had preterm complications e.g. preterm premature rupture of membranes, preterm labour, placental abruption, coagulopathy and severe pre-eclampsia. Three pregnancies progressed to term, two of which had a vaginal delivery and one had an elective caesarean section for malpresentation, all of which were early neonatal deaths. Three women chose to travel abroad in order to obtain a termination of pregnancy. Obstetric and neonatal dilemmas in management of lethal fetal malformation are discussed.

Abnormalities, Multiple↗
PubMed1997

Role of the L-arginine nitric oxide pathway in hypoxic fetoplacental vasoconstriction.

The role of nitric oxide in hypoxic fetoplacental vasoconstriction (HFPV) was investigated using dually perfused human placental cotyledons. Standard medium (Earle's salt solution with added dextran and L-arginine) was equilibrated with 95 per cent O2 and 5 per cent CO2 (maternal side) and 94 per cent N2 and 6 per cent CO2 (fetal side). Part 1 consisted of perfusion for 1 h, then maternal perfusate equilibrated with a 95 per cent N2 and 5 per cent CO2 for 20 min (hypoxia), and then the original perfusion conditions resumed for 40 min. In part 2, this sequence was repeated with standard medium alone (n = 6), or with added N-nitro-L-arginine methyl ester (L-NAME) (n = 6), or L-NAME and nitroglycerin (n = 6). When standard medium was used throughout, basal fetal perfusion pressure (30 +/- 2 mmHg) and the hypoxia-induced increase in perfusion pressure (18 +/- 1 mmHg) did not change significantly between parts 1 and 2. L-NAME increased basal perfusion pressure from 33 +/- 3 to 56 +/- 2 mmHg whereas perfusion pressure remained unchanged with L-NAME and nitroglycerin or nitroglycerin alone. The hypoxic vasoconstriction observed during part 1 in the L-NAME (14 +/- 3 mmHg) and the L-NAME with nitroglycerin groups (18 +/- 2 mmHg) was abolished during part 2 (to - 4 +/- 1 and 0.4 +/- 0.5 mmHg, respectively) whereas nitroglycerin alone significantly blunted the response (21 +/- 3 to 6 +/- 1 mmHg). Results suggest that a reduction in basal NO release mediates hypoxic fetoplacental vasoconstriction in the perfused human placental cotyledon in vitro.

Adult↗
PubMed1996

Cocaine inhibits hCG secretion by the human term placental cotyledon perfused in vitro.

Cocaine has been shown to adversely affect pregnancy outcome in humans, but the mechanism(s) are not well understood. Using the technique of perfusing the human term placental cotyledon in vitro, we measured the rate of hCG appearance in the maternal circulation in the presence and absence of cocaine in the maternal circulation. At a dose of 0.80 microgram/mL, hCG secretion was reduced by 46%. This reduction in hCG concentration in the maternal circulation may effect normal steroidogenesis required to maintain pregnancy and may contribute to our understanding of the reproductive toxicology of cocaine.

Chorionic Gonadotropin↗
PubMed1996

On the structure of social self-concept for pre-, early, and late adolescents: a test of the Shavelson, Hubner, and Stanton (1976) model.

This study is the first to empirically validate the social self-concept component of the R. J. Shavelson, J. J. Hubner, and G. C. Stanton (1976) model. The primary purpose was to test for each of 3 age groups--preadolescents (Grade 3), early adolescents (Grade 7), and late adolescents (Grade 11)-3 hypotheses bearing on the structure of social self-concept within the context of this model: (a) that it is multidimensional, (b) that it is hierarchically ordered, and (c) that it becomes increasingly differentiated with age. Given evidence of a hierarchical social self-concept structure, a secondary focus of the study was to determine the extent to which this pattern held across age. On the basis of the analysis of covariance structures within the framework of confirmatory factor analysis, results revealed a multidimensional social self-concept structure that becomes increasingly differentiated and a hierarchical ordering that becomes better defined with age. Overall, findings were consistent with both the R. J. Shavelson et al. (1976) conceptualization of self-concept structure and developmental processes that underlie self-concept formation.

Adolescent↗
PubMed1996

Measuring depression for Swedish nonclinical adolescents: factorial validity and equivalence of the Beck Depression Inventory across gender.

Building upon earlier confirmatory factor analytic research that validated a 2nd-order 4-factor structure of the Beck Depression Inventory for Canadian and Swedish nonclinical adolescents, the purposes of the present study were twofold: (a) to test the factorial structure of the Swedish version of the instrument separately for males (n = 559) and females (n = 537), and (b) to test for its measurement and structural equivalence across gender. Except for three minor discrepancies involving correlated errors, the hypothesized model best described the data for both males and females. Nonetheless, the imposition of equality constraints across sex revealed differences bearing on the measurement of six items, and latent construct relations involving the Somatic Elements factors. Four gender differences in factorial structure replicated findings for Canadian adolescents. Results have important implications for researchers, clinicians, and others whose interests focus on nonclinical adolescent depression.

Adolescent↗
PubMed1995

Fundulus heteroclitus vitellogenin: the deduced primary structure of a piscine precursor to noncrystalline, liquid-phase yolk protein.

We have cloned and sequenced a cDNA encoding a vitellogenin (Vtg) from the mummichog, Fundulus heteroclitus, an estuarine teleost. We constructed a liver cDNA library against RNA from estrogen-treated male mummichogs. Five overlapping cDNA clones totalling 5,197 bp were isolated through a combination of degenerate oligonucleotide probing of the library and PCR. The cDNA sequence contains a 5,112 bp open reading frame. The predicted primary structure of the deduced 1,704-amino-acid protein is 30-40% identical to other documented chordate Vtgs, establishing this Vtg as a member of the ancient Vtg gene family. Of the previously reported chordate Vtg sequences (Xenopus laevis, Gallus domesticus, Ichthyomyzon unicuspis, and Acipenser transmontanus), all four act as precursor proteins to a yolk which is eventually rendered insoluble under physiological conditions, either as crystalline platelets or as noncrystalline granules. The yolk of F. heteroclitus, on the other hand, remains in a soluble state throughout oocyte growth. The putative F. heteroclitus Vtg contains a polyserine region with a relative serine composition that is 10-20% higher than that observed for the other Vtgs. The trinucleotide repeats encoding the characteristic polyserine tracts of the phosvitin region follow a previously reported trend: TCX codons on the 5' end and AGY codons toward the 3' end. Whether the difference in Vtg primary structure between F. heteroclitus and that of other chordates is responsible for the differences in yolk structure remains to be elucidated. As the first complete teleost Vtg to be reported, these data will aid in designing nucleotide and immunological probes for detecting Vtg as a reproductive status indicator in F. heteroclitus and other piscine species.

Amino Acid Sequence↗
PubMed1995

The Beck Depression Inventory: testing and cross-validating a second-order factorial structure for Swedish nonclinical adolescents.

The intent of the present study was to test for the validity and equivalency of a second-order factorial structure of the Beck Depression Inventory for and across three independent samples (n1 = 661; n2 = 239; n3 = 196) of nonclinical Swedish adolescents. The model under study derived from a cross-validated study of Canadian high school adolescents. Model fitting, testing and equating were based on the analysis of covariance structures within the framework of a confirmatory factor analytic model. Of major importance was the tenability of the hypothesized model for Swedish adolescents. Only minor differences where found among samples, which involved correlated errors and one cross-loading (Sample 2). Results are expected to be of substantial interest to both researchers and clinicians whose concerns focus on depression as it bears on this population.

Adolescent↗
PubMed1993

A review of triplet pregnancy.

Nineteen sets of triplets were delivered in the National Maternity Hospital between January 1st 1980 and December 31st 1990 inclusive. Thirteen triplet pregnancies resulted from spontaneous ovulation and six from ovulation induction therapy for infertility. Management was conservative. Bed rest and home monitoring were not advised routinely and cervical cerclage and tocolytic agents were not used. Ten of the patients were delivered by caesarean section. The prematurity rate was 79% and five sets of triplets were delivered before 32 weeks gestation. The perinatal mortality rate was 35/1000. This reflects a general improvement in the obstetric and neonatal care of triplet pregnancy over the past decade.

Adult↗
PubMed1991

Differentiated additive androgyny model: relations between masculinity, femininity, and multiple dimensions of self-concept.

Masculinity (M) and femininity (F) were related to multiple dimensions of self-concept in 2 large studies. Androgyny theory predicts that M and F contribute positively to self-concept, but the effect of F has been nil in research using global self measures. Here, consistent with the new differentiated additive model, the relative contribution of M and F varied substantially, depending on the area of self-concept; F contributed more positively to self-concept facets that were more stereotypically feminine. Support for the model was consistent across self-responses and responses by significant others (Study 1) and across 5 age groups in early-to-middle adolescence (Study 2).

Adolescent↗
PubMed1990

A clinical review of cervicography.

A new investigative modality, cervicography, has been advocated for cervical screening. In the first 51 patients referred for colposcopy because of an abnormal cervicogram, none had invasive cancer and 75% had preinvasive cancer. The cervicogram appears superior to cytology but inferior to colposcopy in the detection of cervical pathology. Based on the available evidence, however, cervicography cannot be recommended for universal screening. It may have a role in the follow-up of patients with a mildly abnormal cervical smear, but the optimum management remains early referral for colposcopy.

Adult↗
PubMed1989

Rudimentary phosvitin domain in a minor chicken vitellogenin gene.

We have determined the nucleotide sequence and the derived amino acid sequence of the phosphoprotein-encoding region of the chicken vitellogenin III gene. The sequence of this minor vitellogenin could be aligned with exon 22 up to exon 27 of the previously sequenced major vitellogenin II gene (van het Schip et al., 1987). The exon 23 and 25 sequences are rich in serine codons (26% and 41%, respectively), and this region encodes at least one of the small egg yolk phosphoproteins. The major egg yolk phosphoprotein, phosvitin, is encoded by the analogous region in vitellogenin II. Comparison of the vitellogenin II and vitellogenin III sequences shows a great reduction in the size of the putative exon 23 of the latter (321 base pairs as opposed to 690). The number of serine codons is also drastically reduced from 124 in exon 23 of the vitellogenin II gene to 28 in vitellogenin III. The grouping of synonymous serine codons, as has hitherto been observed in sequenced vitellogenin phosphoproteins, has been maintained in vitellogenin III. A putative asparagine-linked N-glycosylation site which was conserved in the chicken vitellogenin II and the Xenopus laevis vitellogenin A2 gene, at the beginning of exon 23, is also present in vitellogenin III. The two chicken vitellogenins show a low conservation in the phosphoprotein-encoding region (average 33%, at the protein level) compared to that in the peripheral sequences (58% identity), which indicates that it is a rapidly evolving domain of the vertebrate vitellogenin gene.

Amino Acid Sequence↗
PubMed1989

Pseudodrusen of the optic disc. Papilledema simulating buried drusen of the optic nerve head.

The distinction between true papilledema and pseudopapilledema rests on characteristics of the optic disc when examined ophthalmoscopically. Buried disc drusen frequently simulate papilledema and often result in misdirected diagnostic maneuvers in search of a cause for presumed intracranial hypertension. When an elevated optic disc exhibits an irregular, "lumpy, bumpy" border, a diagnosis of buried drusen of the optic nerve is usually made. We report a case with papilledema secondary to increased intracranial pressure in which the margins of the swollen optic disc presented this lumpy, bumpy border characteristic of buried drusen. The lumpy character of the disc border disappeared with resolution of the papilledema, and ultrasonography demonstrated the absence of any buried drusen. Other characteristics of papilledema, including extension of the disc swelling into the peripapillary nerve fiber layer, telangiectasia of the superficial vessels of the optic disc, and obscuration of the retinal vessels as they crossed the margins of the optic disc, provided strong evidence of true papilledema and remain the most reliable findings allowing a distinction between true papilledema and pseudopapilledema.

Adult↗
PubMed1988

Echographic characteristics of benign orbital schwannomas (neurilemomas).

We examined two patients with orbital schwannomas (neurilemomas). The echographic findings, including a sharply outlined capsule, a well-defined central cystic space within the tumor with very low internal reflectivity surrounded by smaller cysts with variable reflectivity, slight or no compressibility, and blood flow, should help to differentiate these benign tumors from other orbital lesions. Histologic examination showed a combination of Antoni type A (dense and cellular) and Antoni type B (loose, edematous, or necrotic) patterns.

Adult↗