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Biomedical subjects

W R Blackburn

Publications and source records attributed to W R Blackburn.

At least 19 recordsLinked to original sources
PubMed1998

Vascular anastomoses leading to amelia and cutis aplasia in a dizygotic twin pregnancy.

Dichorionic placentation is observed in both monozygotic (MZ) and dizygotic (DZ) twinning, while monochorionic placentation is unique to MZ twinning. Examinations of monochorionic twin placentas frequently reveal the presence of vascular anastomoses between the two fetal circulations; such anastomoses rarely occur in dichorionic placentas. Consequently, abnormalities resulting from placental vascular communications are almost exclusively observed in MZ twin pairs with monochorionic placentas. We report opposite-sex DZ twins in which vascular anastomoses occurred within a fused dichorionic placenta and were associated with vascular disruptions in one twin. The liveborn male twin had amelia, cutis aplasia, and XX/XY blood chimerism; the female twin died in utero.

Diseases in Twins↗
PubMed1995

Fetal akinesia and multiple perinatal fractures.

Two newborn infants with fetal akinesia sequence were noted to have multiple perinatal fractures of the long bones. The radiographic manifestations are characterized by gracile ribs, thin long bones, and multiple diaphyseal fractures. Consistent histopathologic changes of bone are irregular with focal areas of extreme diaphyseal thinning, thin and long marrow spicules, and with or without callous formation at fracture sites. Pathogenic mechanisms of bone fractures in fetal akinesia sequence and the differential diagnoses of congenital/perinatal bone fractures are discussed.

Adult↗
PubMed1994

Human fetal somatic and visceral morphometrics.

Because of the increasing prenatal use of high-resolution ultrasonography to assess fetal growth and because growth aberration is one of the principal manifestations of abnormal intrauterine development, a more precise definition of normal growth is desirable. Our data set from autopsies of fetuses/neonates (50-4,000 g), collected with systematic attention to precision of measurement, is analyzed and presented. Previous computations of fetal growth curves appear to overstate the variation about the mean. Through the identification and exclusion of outliers and the use of appropriate curve fitting techniques, the problem of overestimation of variation about the mean has been largely eliminated. The new growth standards we present can be used to assess aberration from proportional growth and correlate it with gestational circumstances and particular morphological features of the fetus.

Congenital Abnormalities↗
PubMed1990

Fetal prostate growth and development.

Normal fetal and newborn prostates were studied to evaluate growth patterns, histogenesis, and secretory activity. Whole cross-sectioned prostates harvested from 107 necropsies of fetuses and newborns ages 20 weeks gestation to 1 month of age were used. Development of the prostate occurred in three stages: bud stage (20-30 weeks gestation), bud-tubule stage (31-36 weeks gestation), and acinotubular stage (37-42 weeks gestation). Squamous metaplasia often appeared in the urethra, utricle, and primary lobular ducts, and occasional microcysts were noted. PAS and alcian blue-PAS positive secretion were present in 65% of the specimens by 20-30 weeks gestation and in over 87% of the specimens by 37 or more weeks gestation. Secretory activity was most prominent in the lateral regions of the peripheral zone. Prostate-specific antigen was only weakly detected throughout the prenatal period and was not related to secretory activity as evidenced by the PAS technique.

Antigens, Neoplasm↗
PubMed1988

Cardiovascular pathology in osteogenesis imperfecta type IIA with a review of the literature.

Lethal perinatal osteogenesis imperfecta (OI Type II) is a biochemically diverse collagen disorder characterized by short, crumpled long bones, beaded ribs, blue sclerae and thin, fragile skin. Cardiovascular abnormalities are rarely described. Using morphometry and light and electron (SEM and TEM) microscopy, we analyzed the hearts and great vessels from 2 fetuses with OI Type IIA and compared the findings with age-matched controls. The heart weights and atrioventricular valve (AVV) circumferences were reduced in OI. The chordae tendineae were short and fragile; both the AVVs and the chordae tendineae were hypercellular. TEM showed relatively little organized collagen in the chordae tendineae of OI fetuses. Furthermore, quantitative evaluation of collagen fibril size revealed a decrease in the cross-sectional diameter. There was also a marked decrease in the adventitial and intramural collagen of the intramyocardial arteries and great vessels in OI. Our study reports, for the first time, specific lesions in the cardiovascular systems of patients with OI Type II and reviews the cardiovascular pathology in other forms of OI.

Cardiovascular System↗
PubMed1986

Trend associations of smoking with maternal, fetal, and neonatal morbidity.

Smoking habits, prenatal health, and pregnancy outcome were surveyed among 1700 nulliparous women. During pregnancy, increases in levels of hemoglobin and hematocrit and the frequency of women reporting bleeding and decreases in diastolic pressure and frequency of toxemia were observed with increased maternal smoking. A higher frequency of fetal bradycardia was detected among women smoking greater than or equal to one-half pack per day. With increased smoking there was an increased frequency of abnormal placentas. Mean birth weight and crown-heel length decreased with increased smoking, and neonates born to women smoking greater than or equal to one-half pack per day had a higher frequency of jaundice. The association between smoking and reduced birth weight and crown-heel length persisted after controlling for gestational age, maternal weight gain, prenatal visits, and other confounding variables.

Birth Weight↗
PubMed1980

Bilateral anteromedial defect of the diaphragm in children.

Four cases are reported, along with a review of the literature, to demonstrate the radiographic and clinial spectrum of bilateral anteromedial defect of the diaphragm in infants and children. Bilateral anteromedial defect of the diaphragm produces a characteristic radiographic pattern on herniation of abdominal structures through a single midline opening. The usually solid herniated structures elevate the heart and thymus producing a three-tiered snowman appearance. The lateral chest view substantiates the anterior location differentiating anteromedial herniation from eventration, partial or complete. Diagnosis can be confirmed by pneumoperitoneography but the high incidence of liver herniation allows less invasive determination by radionuclide scanning. While many patients will be asymptomatic, clinical symptoms can be severe due to pulmonary compression and hypoplasia or associated cardiovascular abnormalities.

Child↗
PubMed1977

Lung phosphatidylcholine synthesis and cholinephosphotransferase activity in anencephalic rat fetuses with corticosteroid deficiency.

Adrenocortical insufficiency was produced in rat fetuses by surgical decapitation. These animals show low plasma corticosterone levels compared to littermate controls. Lung slices from anencephalic fetuses were found to have reduced incorporation of [14C]choline into phosphatidylcholine, hence diminished choline pathway activity; this abnoramlity was present at 21 days of gestation but not at term. Cholinephosphotransferase (CPT), the terminal catalyst of the choline pathway, also showed diminished activity in lungs of anencephalic fetuses, with a mean of 120 pmol/min/mg protein compared to a control value of 190. Dexamethasone treatment of these animals for 6-12 hr led to enhanced choline incorporation rates. Corticosteroid administration also restored CPT activity and even elevated the enzyme to a mean level (340 pmol/min/mg protein) greater than that found in normal fetuses at 21-22 days of gestation. The early pulmonary biochemical effects of dexamethasone in this model were not accompanied by recognizable ultrastructural changes.

Adrenal Cortex Hormones↗