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J E O'Brien

Publications and source records attributed to J E O'Brien.

At least 19 recordsLinked to original sources
PubMed2001

VAM-1: a new member of the MAGUK family binds to human Veli-1 through a conserved domain.

The MAGUKs (membrane-associated guanylate kinase homologues) constitute a family of peripheral membrane proteins that function in tumor suppression and receptor clustering by forming multiprotein complexes containing distinct sets of transmembrane, cytoskeletal, and cytoplasmic signaling proteins. Here, we report the characterization of the human vam-1 gene that encodes a novel member of the p55 subfamily of MAGUKs. The complete cDNA sequence of VAM-1, tissue distribution of its mRNA, genomic structure, chromosomal localization, and Veli-1 binding properties are presented. The vam-1 gene is composed of 12 exons and spans approx. 115 kb. By fluorescence in situ hybridization the vam-1 gene was localized to 7p15-21, a chromosome region frequently disrupted in some human cancers. VAM-1 mRNA was abundant in human testis, brain, and kidney with lower levels detectable in other tissues. The primary structure of VAM-1, predicted from cDNA sequencing, consists of 540 amino acids including a single PDZ domain near the N-terminus, a central SH3 domain, and a C-terminal GUK (guanylate kinase-like) domain. Sequence alignment, heterologous transfection, GST pull-down experiments, and blot overlay assays revealed a conserved domain in VAM-1 that binds to Veli-1, the human homologue of the LIN-7 adaptor protein in Caenorhabditis. LIN-7 is known to play an essential role in the basolateral localization of the LET-23 tyrosine kinase receptor, by linking the receptor to LIN-2 and LIN-10 proteins. Our results therefore suggest that VAM-1 may function by promoting the assembly of a Veli-1 containing protein complex in neuronal as well as epithelial cells.

Amino Acid Sequence↗
PubMed2001

Second-trimester biochemical screening.

The past years have seen considerable progress in the area of biochemical screening. Increasing data have now clearly shown the advantages of multiple markers, particularly beta-hCG over AFP alone. There continues to be considerable controversy over the best mathematic algorithm and which markers are best (e.g., beta-HCG, uE3, and so forth). There seems to be a plateau of detection frequencies at about 65% to 70% with current methodologies. Further work needs to be done, however, including some new approaches, if there is to be substantial improvement of screening sensitivity. The combination of biochemical with biophysical parameters as discussed elsewhere in this issue represents the next level of sophistication in the attempt to identify the highest proportion of abnormalities with the fewest false-positives.

Algorithms↗
PubMed2001

Outcome following tricuspid valve detachment for ventricular septal defects closure.

OBJECTIVES: Detachment of the septal leaflet of the tricuspid valve from the annulus (TVD) has been used to improve visualization of ventricular septal defects (VSDs), but may be associated with increased operative time, heart block, and the development of tricuspid regurgitation (TR). METHODS: Patients undergoing VSD closure between 1/1/96 and 31/12/99 were retrospectively reviewed. Follow-up was obtained from the patients' cardiologists. RESULTS: Transatrial VSD closure was performed in 172 patients with TVD in 36 (21%) at the surgeon's discretion. The leaflet incision was repaired with a separate suture (22) or with the VSD patch suture (14). Additional procedures including arch augmentation, closure of atrial septal defects, and closure of additional VSDs were performed in 93 (68%) non-TVD patients and 20 (56%) TVD patients. The median age was 6.2 months (range 1 day to 46 years) and the median weight was 5.9 kg (range 1.5-71.5 kg). Cardiopulmonary bypass (CPB) time was 64+/-24 min and cross-clamp time was 34+/-16 min. One hospital death occurred in an infant with tracheal stenosis. No child in either group developed complete heart block. The median duration of postoperative stay was 4 days (range 2-49 days). There were no differences in CPB time, cross-clamp time or postoperative stay between the TVD and non-TVD groups (P>0.1 for all). At a mean follow-up of 17+/-15 months, there have been two late deaths unrelated to cardiac disease. No child in the TVD group required reoperation for residual VSD, compared to three in the non-TVD group. No child in the TVD group has greater than mild TR, but six in the non-TVD group have greater than mild TR. No child in either group has undergone reoperation for TR. CONCLUSIONS: TVD is a safe, effective technique to improve visualization of VSD and is not associated with heart block, increased operative time, or TR. TVD may result in improved preservation of tricuspid valve architecture and decrease the incidence of significant postoperative TR.

Adolescent↗
PubMed1999

Second-trimester maternal serum marker screening: maternal serum alpha-fetoprotein, beta-human chorionic gonadotropin, estriol, and their various combinations as predictors of pregnancy outcome.

OBJECTIVE: We evaluated the value of all 3 common biochemical serum markers, maternal serum alpha-fetoprotein, beta-human chorionic gonadotropin, and unconjugated estriol, and combinations thereof as predictors of pregnancy outcome. STUDY DESIGN: A total of 60,040 patients underwent maternal serum screening. All patients had maternal serum alpha-fetoprotein measurements; beta-human chorionic gonadotropin was measured in 45,565 patients, and 24,504 patients had determination of all 3 markers, including unconjugated estriol. The incidences of various pregnancy outcomes were evaluated according to the serum marker levels by using clinically applied cutoff points. RESULTS: In confirmation of previous observations, increased maternal serum alpha-fetoprotein levels (>2.5 multiples of the median) were found to be significantly associated with pregnancy-induced hypertension, miscarriage, preterm delivery, intrauterine growth restriction, intrauterine fetal death, oligohydramnios, and abruptio placentae. Increased beta-human chorionic gonadotropin levels (>2.5 multiples of the median [MoM]) were significantly associated with pregnancy-induced hypertension, miscarriage, preterm delivery, and intrauterine fetal death. Finally, decreased unconjugated estriol levels (<0.5 MoM) were found to be significantly associated with pregnancy-induced hypertension, miscarriage, intrauterine growth restriction, and intrauterine fetal death. As with increased second-trimester maternal serum alpha-fetoprotein levels, increased serum beta-human chorionic gonadotropin and low unconjugated estriol levels are significantly associated with adverse pregnancy outcomes. These are most likely attributed to placental dysfunction. CONCLUSION: Multiple-marker screening can be used not only for the detection of fetal anomalies and aneu-ploidy but also for detection of high-risk pregnancies.

Abruptio Placentae↗
PubMed1999

Determination of reference values for a novel ketoamine-specific fructosamine assay for assessment of diabetic glycemic control.

BACKGROUND: Intensive monitoring to improve glycemic control is essential for effective management of diabetes and reduction of long-term morbidity and pathology. Measurement of glycated serum proteins (fructosamine) allows more frequent assessment (monthly) of glycemic control than the 2- to 3-month window of the traditional glycated hemoglobin (HbA1c) assay. In response to concerns about assays designed to measure glycated serum proteins based on the nitroblue tetrazolium (NBT) methodology, a novel assay to measure glycated serum proteins has been developed based on the specific oxidation of the ketoamine bonds within the glycated proteins. METHODS: Reference range values for this new, enzymatic glycated-serum-protein assay (GlyPro; Genzyme Corporation, Cambridge, MA) are reported. RESULTS: The GlyPro reference range is lower and shows close correlation with ranges reported for the NBT assay. The 95% overall reference range was 122 to 236 mumol/L. CONCLUSIONS: GlyPro is a reliable, accurate assay and correlates well with the NBT assay for the measurement of glycated serum proteins. The assay may be useful in the short-term assessment of diabetes control, a necessary complement to long-term control as assessed by hemoglobin A1c (HbA1c) assays.

Adult↗
PubMed1999

Screening for aneuploidy.

Over the past 15 years, biochemical screening for chromosomal abnormalities, particularly Down's syndrome, has advanced from being extremely naive, to now somewhat more sophisticated. Sensitivities have gone from 20% to 60-70%. Considerable work is still required to not only increase the sensitivity, but also the specificity to keep health care costs down.

Aneuploidy↗
PubMed1998

Detection of anomalies: alternatives to ultrasound.

Ultrasound and biochemical screening are complementary screening tests that each have limitations and advantages. The next several years will see variable progress in the evolution of these techniques, which, it is hoped, will result in an appropriate role for each to achieve a cost-effective, highly sensitive and specific screening approach that will allow couples the most comfort in detecting problems during pregnancy, as well as a high degree of confidence that normal results are accurate.

Algorithms↗
PubMed1998

Fetal gender impact on multiple-marker screening results.

Maternal serum alpha-fetoprotein (MSAFP), human chorionic gonadotropin (hCG), and unconjugated estriol (uE3) are used in combination with maternal age to calculate the risk for Down syndrome (DS) in pregnancy. Increased levels of hCG and decreased levels of MSAFP and uE3 are consistent with an increased risk for DS. We retrospectively evaluated second-trimester maternal serum marker levels in a large cohort of patients with known normal outcomes and documented fetal gender. These included 15,428 patients who had MSAFP measurements, 11,428 patients with both MSAFP and hCG, and 6,090 patients with all three markers including uE3. MSAFP levels in patients with female fetuses were consistently lower than those with males. Conversely, hCG was higher in pregnancies with females as compared to males. No gender-related difference was noted for uE3. These results would suggest that the computed DS risk for female fetuses is higher than for males, despite the fact that the incidence of DS is similar in both genders. This information could be useful for calculating gender-specific DS risk; however, this would require ultrasonographic determination of fetal sex.

Biomarkers↗
PubMed1998

Combination of elevated maternal serum alpha-fetoprotein (MSAFP) and low estriol is highly predictive of anencephaly.

Increased levels of second trimester maternal serum alpha-fetoprotein (MSAFP) have long been established as a marker for neural tube defects (NTDs). In addition, decreased levels of maternal estriol in the third trimester have been reported in pregnancies with anencephalic fetuses. The purpose of this study was to evaluate whether early second trimester unconjugated serum estriol (uE3) is an independent predictor of NTDs. The study included 57,031 patients who underwent maternal serum screening with MSAFP at 14-22 weeks gestation. Of these, 23,415 also had uE3 measurements. There were 63 cases of NTD, an overall incidence of 1.1 per 1,000. Elevated MSAFP (> or =2.5 MOM) was detected in 1,346 patients, 48 of which had NTDs. Decreased uE3 (< or =0.5) was detected in 1,437 patients, 17 of which had NTDs. The incidence of NTDs was significantly higher in patients with low uE3, compared to patients with normal/high uE3 (1.15% vs. 0.09%, P < 001). Finally, 51 patients had both increased MSAFP and decreased uE3; 16 of these had NTDs, 14 of which were anencephalics. In conclusion, both elevated MSAFP and low maternal serum estriol are predictive of NTD but have a low sensitivity. The combination of abnormally elevated MSAFP and low estriol is highly predictive of NTD in particular anencephaly.

Anencephaly↗
PubMed1998

Effect of adjustment of maternal serum alpha-fetoprotein levels in insulin-dependent diabetes mellitus.

Our objective was to determine the effect of the 20% upward adjustment of maternal serum alphafetoprotein (MSAFP) in patients with insulin-dependent diabetes mellitus (IDDM) on the number of patients that would be classified at increased risk for pregnancy complicated by either Down syndrome (DS) or neural tube defect (NTD). We retrospectively evaluated a database containing 63,110 patients who underwent multiple serum marker screening between 14 and 22 weeks gestation; 620 patients with IDDM had measurements of MSAFP of which 479 also had measurements of beta-HCG, allowing calculation of DS risk. Increased NTD risk was defined as MSAFP >2.5 MOM while increased DS risk was defined as a calculated risk > or =1/270. One IDDM patient delivered an infant with a NTD; it was not detected on serum screening. No infants were born with DS. Of the 620 patients with MSAFP determinations, 9 had values >2.5 MOM before adjustment. After upward adjustment, 7 additional patients were identified. Sixteen patients were identified at increased risk for DS before and after adjustment. Our data suggest that the 20% upward adjustment of MSAFP increases by 78%, the number of patients who would require further evaluation for NTD's. Although we were able to identify 620 women with IDDM who underwent serum screening for NTD, the low prevalence of NTD's did not allow us to demonstrate an increased detection rate. The effect of upward adjustment of MSAFP on the number of patients categorized at increased DS risk appears to be minimal.

Adult↗
PubMed1998

Age-specific variation in aneuploidy incidence among biochemical screening programs.

OBJECTIVE: Our purpose was to compare the observed age-related incidence of Down syndrome in two large screening programs with the commonly quoted incidences used in biochemical screening programs. STUDY DESIGN: Data from two large prenatal screening programs were stratified in 5-year age groups. The age-related incidence of Down syndrome was compared with the commonly used incidence as reported by Cuckle. RESULTS: No significant differences were found in age-related incidences of Down syndrome in any age group between the screening groups or among women ages 15 through 29 in any of the three groups. However, for women 30 to 34 and > or = 40 years old, a trend was noted toward a higher incidence in the screening groups. For women ages 35 to 39, the observed incidence was significantly greater in the screening groups compared with the data of Cuckle. CONCLUSION: Our data suggest an underascertainment in Down syndrome risk built into the Cuckle model, particularly in high-risk patients.

Adolescent↗
PubMed1998

Early injury to the media after saphenous vein grafting.

BACKGROUND: Injury to the smooth muscle cells of the media affects the remodeling process of vein grafts. The purpose of this study was to determine whether different techniques of surgical preparation influence the degree of medial smooth muscle injury. METHODS: Carotid-saphenous vein interposition grafting was performed in crossbred pigs (n = 32), using distended (n = 16) or nondistended (n = 16) conduits. After 3 to 90 days, the media was evaluated for the presence of smooth muscle cells (desmin stains), myofibroblast formation (transient alpha-SM actin expression), and apoptosis (TdT-mediated dUTP nick end-labeling [TUNEL]). RESULTS: Smooth muscle loss was uniformly severe; only 5% +/- 5% (p < 0.01) and 14% +/- 9% (p < 0.01) of the medial area of distended and nondistended veins were desmin positive in comparison with 80% +/- 9% of controls. Apoptosis appeared to contribute to medial smooth muscle loss (5.7% +/- 4.3% in vein grafts versus 0.0% +/- 0.0% of TUNEL-positive cells in controls; p = 0.05). There was a time dependent increase in medial myofibroblast formation (p < 0.05). CONCLUSIONS: Severe medial smooth muscle loss occurs in vein grafts, even when prepared without distension. Apoptosis contributes to the early disappearance of smooth muscle cells. Adjunctive measures, in addition to ideal surgical techniques, should be developed to prevent medial muscle loss.

Actins↗
PubMed1998

Sustained reduction of neointima with c-myc antisense oligonucleotides in saphenous vein grafts.

BACKGROUND: Treatment of saphenous veins with c-myc antisense oligomers during preparation for grafting reduces medial cellular proliferation and macrophage infiltration, and preserves medial smooth muscle content at 3 days. Accordingly, the purpose of this study was to examine whether c-myc antisense oligomers have an impact on late vein graft remodeling. METHODS: Sixty-two pigs underwent unilateral saphenous vein-carotid artery interposition grafting. Harvested veins were incubated either in saline (control group) or 20-micromol/L or 200-micromol/L concentrations of c-myc antisense oligomers (treated groups) for 30 minutes intraoperatively. Three months after surgery, vein graft histology was assessed. RESULTS: Forty-five of 62 randomized animals survived the experiment; no differences in animal survival or graft patency among the groups were observed (p = NS, chi2). C-myc antisense oligomers significantly decreased neointimal and wall thickness, as well as increased lumenal index, in treated groups (p<0.04, p<0.03, and p<0.001, respectively, analysis of variance). In contrast, there was no difference in medial thickness or perivascular wound healing. CONCLUSION: Intraoperative treatment of saphenous veins with c-myc antisense oligomers decreased neointimal formation at 3 months after grafting. In conjunction with our previous reports, these findings suggest that early inhibition of cellular proliferation and inflammatory infiltration results in a sustained reduction in neointimal formation and favorable graft remodeling.

Animals↗
PubMed1998

Saphenous vein graft protection: effects of c-myc antisense.

OBJECTIVE: Saphenous vein grafting is associated with extensive medial remodeling, characterized by cellular proliferation, loss of smooth muscle cells, and an inflammatory response. In this study, we examined whether unfavorable responses to vein grafting could be modified by the intraoperative application of c-myc antisense oligomers. METHODS: The intragraft cell proliferation, macrophage infiltration, and medial preservation were examined in a porcine model in the control and antisense-treated groups (n = 36). RESULTS: Saphenous veins showed transmural distribution of oligomers within 30 minutes of the ex vivo incubation. A concentration-dependent inhibition of cell proliferation in the media of saphenous grafts was noted 3 days later (0 to 200 mumol/L, p = 0.005). The growth inhibition was sequence-specific, because control oligomers produced only insignificant effects (20 mumol/L). Vascular effects of c-myc antisense were associated with a significant attenuation of macrophage infiltration in saphenous grafts. A concentration-dependent decrease in tissue edema (p = 0.0005) and the attenuated loss of smooth muscle cells (p = 0.002) were noted in the media of the arterialized venous conduits after c-myc antisense. CONCLUSIONS: Direct application of synthetic DNA to harvested saphenous veins resulted in a rapid transmural distribution. The inhibition of the intragraft cell proliferation in vivo after c-myc antisense was sequence dependent. Decrease in vein graft injury resulted in an attenuated inflammatory response and better medial preservation. These findings provide a rationale for assessment of the long-term effects of vein graft protection with c-myc antisense.

Animals↗
PubMed1997

Differential increases in AFP, hCG, and uE3 in twin pregnancies: impact on attempts to quantify Down syndrome screening calculations.

Since the advent of multiple marker screening (MMS) for Down syndrome (DS) risk calculations, limitations for twins have been apparent. Recent attempts have been made to extrapolate mathematically singleton risks to twins. Here we investigate the pattern of levels among AFP, hCG, and uE3 in twins. MMS screening data from 4,443 twin pregnancies were compared to those from 258,885 singletons from 14-21 weeks of gestational age during a 3-year period (1992-1994) in our laboratory. Medians were determined for singletons and twins, and the ratios of twins to singletons were derived. Median AFP levels for twins are approximately double those of singletons, but median increases for hCG and uE3 are less than double. The data were divided further by ethnic groups (white, African American, Asian, and Hispanic), among which there were significant variations in medians, but not in the ratios of twins to singletons. The increased serum levels of different markers in twins are not consistent across analytes, possibly reflecting independent development of different compartments. Such differences mean that a mere mathematical conversion of singleton DS risks would be imbalanced among the analytes and cannot be applied reasonably to twins. Ethnic-specific databases are as important in twins as they are in singletons.

Biomarkers↗
PubMed1997

Remodeling of autologous saphenous vein grafts. The role of perivascular myofibroblasts.

BACKGROUND: Aortocoronary saphenous vein grafts (SVGs) undergo structural changes that render them susceptible to atherosclerosis. Accordingly, the origin of neointimal hyperplasia-was examined in porcine arterialized SVGs to determine the mechanism of vein graft remodeling. METHODS AND RESULTS: At 2 to 4 days after surgery, the percentage of cells lacking differentiation markers characteristic for smooth muscle (SM) cells (ie, alpha-SM actin, desmin, and SM myosin) increased within the media of SVGs interposed in the carotid arteries (P < .001). At 7 to 14 days, these cells acquired a differentiated phenotype (ie, alpha-SM-actin positive/ variable desmin/SM-myosin negative) and accumulated in the neointima. At 3 months, the neointima was positive for alpha-SM actin but mostly negative for desmin, which contrasted with medial SMCs that were invariably positive for alpha-SM actin, desmin, and SM myosin. To determine the role of nonmuscle cells in the above process, perivascular wound fibroblasts were selectively labeled and found to translocate through the media of newly placed SVGs, contributing to neointimal formation. These migrating cells differentiated to myofibroblasts exhibiting sustained alpha-SM-actin expression. The intima of human SVGs, retrieved during repeat aortocoronary bypass surgery, exhibited the profile of cytoskeletal proteins that resembled myofibroblasts seen in porcine SVGs. CONCLUSIONS: Perivascular fibroblasts may infiltrate injured media of arterialized SVGs, differentiate to myofibroblasts (acquiring alpha-SM actin), and contribute to vein graft remodeling. The similarities between porcine and human SVGs regarding the repertoire of cytoskeletal proteins suggest the involvement of myofibroblasts in graft remodeling in the clinical setting.

Actins↗