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Biomedical subjects

J C Morrison

Publications and source records attributed to J C Morrison.

At least 91 records · Page 5Linked to original sources
PubMed1997

Are obstetric interventions such as cervical ripening, induction of labor, amnioinfusion, or amniotomy associated with umbilical cord prolapse?

OBJECTIVE: Our purpose was to determine whether intrapartum obstetric interventions are associated with umbilical cord prolapse. STUDY DESIGN: A computer search identified patients who had intrapartum umbilical cord prolapse. Thirty-seven cases were identified between 1990 and 1994 (incidence of 1.85 per 1000). These women were randomly matched to control patients with intact membranes. RESULTS: Patients with umbilical cord prolapse were delivered earlier (34.8 vs 37.1 weeks, p = 0.05). Otherwise, there were no differences between groups regarding the use of cervical ripening, incidence of labor induction, or the use of amnioinfusion and amniotomy. Although cervical dilatation and station were similar between groups at the time of admission, women with umbilical cord prolapse did not have as much descent of the presenting part associated with cervical dilatation and progressive labor compared with control patients. CONCLUSION: By themselves, obstetric interventions of cervical ripening, labor induction, amnioinfusion, and amniotomy do not increase the likelihood that a patient will have umbilical cord prolapse.

Adolescent↗
PubMed1997

Sonographic examination does not predict twin growth discordance accurately.

OBJECTIVE: To assess the accuracy of estimating birth weight among twins with discordancy (intra-pair difference in actual birth weight of more than 25%) and to determine the relative accuracy of an intra-pair difference in abdominal circumference (delta AC) of 20 mm or more or in estimated fetal weight (delta EFW) of 25% or more for the identification of discordant growth in twins. METHODS: Over a 6-year period, we identified all non-anomalous twin pairs with gestational ages greater than 23 weeks and sonographic examinations within 3 weeks of birth. Ultrasonographic biometry of both twins included AC, head circumference, and femur length; these indices were used to estimate fetal weight by Hadlock's formula. Likelihood ratios, receiver-operating characteristic curves, and prediction limits were applied to assess the accuracy of the two diagnostic methods to predict an abnormal outcome. RESULTS: A total of 242 twin pairs were studied. The mean gestational age among the 21 twins with abnormal growth (30.6 +/- 4.6 weeks) was significantly less than among the 221 twins with normal growth (33.2 +/- 4.0 weeks) (P < .005). The biometric measurements of fetal parts, sonographic estimate of fetal weight, and actual birth weight for both fetuses were significantly less for discordant twin pairs (P < .05). The accuracy of predicting birth weight, as determined by mean error and percentage of the estimate within 10% of the actual weight, was similar between the groups. Receiver-operating characteristic curves showed that both diagnostic tests yielded areas under the two curves not significantly different from the area under the nondiagnostic line (P > .05). Most important, prediction limit calculations indicated that a 90% certainty that the actual birth weight discordance was at least 25% was achievable only if delta AC was 172 mm or greater or delta EFW was 112% or more. CONCLUSION: The most popular current methods (difference in AC or EFW) for predicting discordant growth in twin gestations have limited accuracy when held to a standard for discordance that requires a birth weight difference of at least 25%.

Birth Weight↗
PubMed1997

A randomized trial of two vacuum extraction techniques.

OBJECTIVE: To determine whether two techniques of vacuum extraction delivery-continuous vacuum and intermittent vacuum-have different effects on maternal-fetal outcomes. METHODS: Patients to be delivered by vacuum extraction were randomized to receive continuous or intermittent vacuum. All deliveries were performed using the M-cup. In the continuous group, the level of vacuum was brought to 600 mmHg between contractions and was maintained at that level until delivery of the infant. Active efforts were made to prevent fetal loss-of-station between contractions by maintaining traction. In the intermittent group, the level of vacuum was decreased to 100 mmHg between contractions and no effort was made to prevent fetal loss-of-station. RESULTS: A total of 322 patients were randomized: 164 in the continuous arm and 158 in the intermittent group. The continuous method did not effect delivery faster (continuous 167 +/- 175 seconds versus intermittent 167 +/- 150 seconds; P = .97), nor did it lead to a reduction in method failures (continuous 12, intermittent nine; P = .72). The intermittent method did not appear to offer any benefit to the neonate regarding cephalhematoma formation (continuous 20, intermittent 17; P = .686) or any other measure of neonatal outcome. Maternal lacerations and episiotomy extensions were evenly distributed between the groups. Overall, the efficacy rate of the vacuum cup was 93.5% and the cephalhematoma rate was 11.5%. CONCLUSION: No differences in maternal or fetal outcome could be demonstrated if the level of vacuum was decreased between contractions or if an effort was made to prevent fetal loss-of-station. The clinical results obtained in this trial using the M-cup are similar to the published results with the stainless-steel Malmstrom cup.

Adult↗
PubMed1997

Amniotic fluid volume in normal singleton pregnancies.

OBJECTIVE: To evaluate the amniotic fluid (AF) volume in normal singleton pregnancies from 15 to 40 weeks. METHODS: This prospective study evaluated the AF volume in singleton pregnancies undergoing amniocentesis for genetic assessment of fetal karyotype, preterm labor, or fetal lung maturity. Amniotic fluid volume was determined using a dye dilution technique. To assess the relationship between AF volume and estimated gestational age, a nonlinear regression model was applied. RESULTS: One hundred forty-four normal singleton pregnancies had AF volume evaluated. There was wide variability in the measured AF volumes with a significant (P < .01) increase in AF volume as a function of gestational age. Growth curve modeling estimated that AF volume continued to increase until 40 weeks' gestation. Analyses of the observed AF volume indicated that AF volume nearly doubled after 30 weeks' gestation. CONCLUSION: In contrast to other reports indicating that maximal AF volume in singleton gestations is expected early in the third trimester, we observed the attainment of maximal AF volume near term.

Adult↗
PubMed1997

The coenzyme A-synthesizing protein complex and its proposed role in CoA biosynthesis in bakers' yeast.

An improved procedure is described for the recovery and purification of the coenzyme A-synthesizing protein complex (CoA-SPC) of Saccharomyces cerevisiae (bakers' yeast). The molecular mass of the CoA-SPC, determined prior to and following its purification, is estimated by Sephacryl S-300 size exclusion chromatography to be between 375,000-400,000. Two previously unreported catalytic activities attributed to CoA-SPC have been identified. One of these is CoA-hydrolase activity which catalyzes the hydrolysis of CoA to form 3',5'-ADP and 4'-phosphopantetheine, and the other is dephospho-CoA-pyrophosphorylase activity which catalyzes a reaction between 4'-phosphopantetheine and ATP to form dephospho-CoA. The dephospho-CoA then reacts with ATP, catalyzed by the dephospho-CoA-kinase, to reform CoA. This sequence of reactions, referred to as the CoA/4'-phosphopantetheine cycle, provides a mechanism by which the 4'-phosphopantetheine can be recycled to form CoA. Each turn of the cycle utilizes two mol of ATP and produces one mol of ADP, one mol of PPi, and one mol of 3',5'-ADP. Other than the hydrolysis of CoA by CoA-SPC, the 4'-phosphopantetheine for the cycle apparently could be supplied by alternate sources. One alternate source may be the conventional pathway of CoA biosynthesis. Intact CoA-SPC has been separated into two segments. One segment is designated apo-CoA-SPC and the other segment segment is referred to as the 10,000-15,000 M(r) subunit. The 5'-ADP-4'-pantothenic acid-synthetase, 5'-ADP-4'-pantothenylcysteine-synthetase, 5'-ADP-4'-pantothenylcysteine-decarboxylase, and CoA-hydrolase activities reside in the apo-CoA-SPC segment of CoA-SPC. Whereas the dephospho-CoA-kinase and the dephospho-CoA-pyrophosphorylase activities reside in the 10,000-15,000 M(r) subunit. Thus, the 10,000-15,000 M(r) subunit mimics the bifunctional enzyme complex that catalyzes the final two steps in the conventional pathway of CoA biosynthesis.

Catalysis↗
PubMed1997

Dose uniformity from a computerized three-dimensional tissue compensating system.

A verification of dose uniformity of the Huestis Compu-Former, a three dimensional megavoltage tissue compensator, is presented. Tissue compensators were built for three different anthropomorphic phantoms: a head and neck, a mantle, and a breast. Film densitometry was used to evaluate the effectiveness of the tissue compensators by comparing isodose curves generated for a compensated and an uncompensated field. Evaluation of the isodose distributions for the three regions confirmed the use of the Compu-Former as a reliable tissue compensating system.

Breast↗
PubMed1997

Remote umbilical arterial blood pH analysis: accuracy, utility, and limitations.

It is not always possible or feasible to perform routine umbilical artery blood sampling at birth. This study was undertaken to assess the accuracy of selective remote umbilical arterial blood analysis to retrospectively predict the original birth pH of any newborn. Umbilical arterial blood samples were obtained in two preheparinized syringes immediately following 1007 deliveries. One sample was analyzed within 60 minutes of delivery. The other was placed on ice and later analyzed at variable time intervals up to 180 hours postpartum. The results of each remote analysis were adjusted using a previously published regression equation to accurately identify which newborns had pH values < 7.00, < or = 7.10, or < 7.20 at birth. Among the 1007 newborns, there were 14 (1.3%), 44 (4.3%), and 187 (18.5%) who had pH values < 7.00, < or = 7.10, and < 7.20, respectively, at birth. Remote umbilical arterial samples analyzed within 72 hours of delivery correctly identified newborns with an original pH < 7.00, < or = 7.10, or < 7.20 with: (1) a sensitivity of 100, 82, and 84%, respectively; (2) positive predictive values of 100, 93, and 66%, respectively; and (3) a test efficiency of 100, 99, and 89%, respectively. Up to 72 hours after delivery, remote umbilical arterial blood pH analysis can be reliably used to accurately identify the newborn that was acidotic at birth.

Acidosis↗
PubMed1997

Use of fetal fibronectin in clinical practice.

Preterm delivery remains a worldwide problem hindered by many unknowns, not the least of which is an inability to detect patients at risk for this complication of pregnancy. A unique form of fibronectin identified in the extracellular matrix surrounding the extravillous trophoblast at the uteroplacental junction contains an epitope called the "oncofetal domain," which is recognized by the monoclonal antibody FDC-6. When detected in cervicovaginal secretions of both symptomatic patients as well as asymptomatic women who have risk factors for early deliver, fetal fibronectin seems to be a marker for preterm delivery with a good positive predictive value (40-60 percent). A negative result has a negative predictive value of 99.5 percent for birth within 7 days and 92 percent for delivery before 37 weeks in those patients with signs and symptoms of preterm labor. In low-risk asymptomatic patients, the positive predictive value is lower (15-25 percent), but is important because women in this group, destined to deliver as a consequence of preterm labor, may have no other signs or symptoms to forebode preterm delivery. Fetal fibronectin testing could also be important in women in spurious preterm labor who may eventually deliver before 37 weeks' gestation. Although specific interventional studies are still needed, this test is an important step forward in the provider's armamentarium to reduce the impact of a preterm delivery.

Biomarkers↗
PubMed1997

Premature rupture of membranes at term with an unfavorable cervix: comparison of expectant management, vaginal prostaglandin, and oxytocin induction.

BACKGROUND: Our objective was to determine the best treatment for parturients at term with an unfavorable cervix and premature rupture of membranes (PROM). METHODS: In this prospective study, 96 women with PROM and an unfavorable cervix were randomized into one of three treatment groups: oxytocin induction, vaginal prostaglandin E2 gel followed by oxytocin, or expectant management. RESULTS: Length of labor, cesarean section rate, and maternal/neonatal morbidity were not significantly different. In contrast, the interval from PROM until delivery and length of hospital stay were significantly longer in the expectantly managed group than in the other groups. Four of the patients who received expectant management required delivery because of nonreassuring fetal assessments. CONCLUSIONS: Expectant management of PROM at term significantly prolongs hospital stay without decreasing the incidence of abdominal delivery or infectious morbidity. There appears to be potential for cord compression in patients managed expectantly without continuous electronic fetal surveillance.

Cesarean Section↗
PubMed1997

Screening for human immunodeficiency virus infection during pregnancy.

Due to the increased risk of human immunodeficiency virus (HIV) infection during the childbearing years, voluntary screening during the prenatal period has been suggested. To study the impact of such a program in our population of pregnant women, we offered HIV testing to all prenatal patients with informed consent, beginning January 1, 1992. After 18 months (July 1993), HIV testing was offered as a component of our prenatal laboratory panel, using informed refusal. During the first screening period, there were 20 seropositive women among the 14,143 patients (1.4/1000), with 74 refusing testing. During the next 36 months (July 1993 to June 1996), 91 seropositive gravidas were identified among 31,496 parturients (2.9/1000), with only 17 refusing assessment. Free treatment with zidovudine (AZT) for both mother and baby, sponsored by the Mississippi state health department, began in January 1994. The perinatal transmission rate was 33% before AZT treatment, during our period of assessment, and was reduced to 10% during the next 30 months. Based on our data, it appears that a program of universal voluntary screening for HIV infection using informed refusal and free AZT for patients at risk for perinatal transmission results in almost 100% testing and a reduction in vertical transmission.

Female↗
PubMed1997

Twins and preterm labor.

OBJECTIVE: To assess the effect of home uterine contraction assessment (HUCA) in twin pregnancies with preterm labor (PTL) at < 24 weeks' gestation. STUDY DESIGN: In this retrospective, analytic study, patients were stratified by whether HUCA had been prescribed before or after diagnosis of PTL. The main outcomes studied were time of PTL diagnosis and delivery as well as birth weight and need for neonatal intensive care unit (NICU) admission. In 63 patients, 32 were prescribed HUCA after PTL had been arrested at < 24 weeks (group I). Thirty-one women had HUCA prescribed at 20 weeks' gestational age and then developed PTL at < 24 weeks (group II). RESULTS: Labor was diagnosed at similar times in both groups (22.8 vs 23.4 weeks), but delivery was earlier in group I (27.6 weeks vs. 34.7 weeks) than in group II. The birth weight in group I was less (918 +/- 255 g), and of the 64 infants, 55 required NICU admission as compared to 2,340 +/- 525 g and 11 of 62 infants (P < .0001, .0001) in group II, respectively. CONCLUSION: Women with twin gestations and the diagnosis of PTL prior to 24 weeks deliver later in gestation, and their infants weigh more and have fewer NICU admissions if intensive prenatal surveillance is prescribed prior to the onset of labor.

Adult↗
PubMed1997

Cesarean section for suspected fetal distress. Does the decision-incision time make a difference?

OBJECTIVE: To compare perinatal outcomes in patients at term (37 weeks) in whom the decision-incision time for cesarean delivery was due to suspected fetal distress. STUDY DESIGN: All parturients who underwent cesarean delivery primarily for possible fetal distress during a three-year period were identified retrospectively. Student's t test and the chi 2 test were utilized, and P < .05 was considered significant. A regression analysis of decision-incision time and umbilical arterial pH was performed. RESULTS: From 1991 to 1993, 1.3% (117/9,137) of term laboring patients underwent emergency cesarean delivery for the primary indication of possible fetal distress. In 61 patients (52%) the decision-incision time was 30 minutes, while it exceeded 30 minutes in the remaining 56 women. The two patient groups were similar in maternal demographics, antepartum complications, oxytocin usage, thick meconium, type of abnormal fetal heart rate tracing prompting surgery, use of amnioinfusion (41% vs. 36%), general anesthesia (97% vs. 93%), mean birth weight and Apgar score < 7 at five minutes. Three adverse outcomes were observed more frequently in association with decision-incision time > 30 minutes: (1) lower mean (+/-SD) umbilical arterial pH (7.16 +/- 0.15 vs. 7.26 +/- 0.06, P = .001), (2) pH < 7.00 (8/61 vs. 0/56, P = .005), and (3) admission to the neonatal intensive care unit (P = .008). When the incision was made longer than 30 minutes after the decision, there was no apparent adverse neonatal or infant outcome. CONCLUSION: Although a cesarean decision-incision time < or = 30 minutes is a desirable goal for the fetus possibly in distress, failure to achieve this goal is not associated with a measurable negative impact on newborn outcome.

Adult↗
PubMed1997

Neonatal cephalohematoma from vacuum extraction.

OBJECTIVE: To identify factors involved in the development of fetal cephalohematoma from vacuum extraction. STUDY DESIGN: Patients at > or = 34 weeks' gestation were randomly assigned to delivery by vacuum (n = 322) using the continuous (n = 164) or intermittent (n = 158) technique. Neonatal outcome with cephalohematoma was analyzed subsequently and related to prospectively recorded data. RESULTS: Approximately equal numbers of cephalohematoma were recorded in the two groups (continuous 20, intermittent 17; P = .686). Station at point of application (P = .008), increasing asynclitism (P < .001) and increasing application to delivery time (P = .002) correlated significantly with cephalohematoma. Only the last two factors achieved significance after stepwise multiple logistic regression analysis. Factors that did not achieve statistical significance were gestational age (P = .755), birth weight (P = .982), instrumental rotation (P = .896) and previous vaginal delivery (P = .051). CONCLUSION: In this prospective, randomized, controlled trial of vacuum-assisted delivery, the only predelivery factor found to predispose to neonatal cephalohematoma formation was increasing asynclitism. Although cephalohematoma formation was more likely to develop as the duration of vacuum application increased during delivery, only 28% of neonates exhibited this finding when the time from vacuum application to delivery exceeded five minutes.

Female↗
PubMed1997

Comparison of pregnancy outcome between treated and untreated women with chlamydial cervicitis.

BACKGROUND: Maternal, fetal, neonatal, and infant outcome in treated versus untreated pregnant women with positive endocervical cultures for Chlamydia trachomatis is controversial. METHODS: One thousand three hundred fifty pregnant women registering consecutively on the staff clinic service were screened for chlamydia. The results of the antigen, but not the culture tests, were available for clinical management. RESULTS: Eighty one patients had positive chlamydia cultures, a prevalence rate of 5.1%. Fifty eight patients were not treated, 44 because of false-negative direct antigen tests. Twenty three patients were treated. Maternal complications including abortion, preterm rupture of membranes, preterm delivery, chorioamnionitis, and endometritis were similar in the two groups. Similarly, neonatal and infant complications including prematurity, conjunctivitis, and pneumonia were similar in the two groups. CONCLUSIONS: Our findings suggest that further prospective, controlled culture based studies are needed before recommending routine screening for chlamydia even in high risk populations.

Adolescent↗
PubMed1996

The effect of chronically elevated intraocular pressure on the rat optic nerve head extracellular matrix.

The extracellular matrix of the optic nerve head is altered in both human glaucoma and in experimental primate models of this disease. However, the relationship of this change to glaucomatous optic nerve degeneration is unknown. This report describes similar matrix alterations in rats with unilateral elevated intraocular pressure. Brown Norway rats received episcleral vein injections of hypertonic saline to produce prolonged elevations of intraocular pressure. After up to 6 months of pressure elevation, optic nerve head sections from the rats were evaluated by light microscopic immunohistochemistry using antibodies to collagens I, III, IV and VI, laminin, elastin and chondroitin and dermatan sulfate proteoglycans. In experimental eyes with 11 days or more of pressure elevation, depositions of collagen IV, collagen VI and laminin were found within regions of the optic nerve head that, in normal eyes, are occupied solely by nerve bundles. Collagen I and III deposition appeared to be more dependent on the level and duration of the pressure rise. Eyes with lower mean intraocular pressures showed deposits of interstitial collagens primarily at the level of the sclera, while eyes with higher mean pressure elevations had depositions in the neck regions as well. Chondroitin and dermatan sulfate proteoglycans were deposited in a pattern similar to that of collagen I. No extracellular matrix deposition was seen in the orbital optic nerve in any experimental eye. These extracellular matrix changes in rats replicate previous findings in human glaucomatous eyes and monkey eyes with experimentally elevated pressures. They also suggest a sequence of extracellular matrix protein deposition in response to pressure elevation. The optic nerve head deposition of matrix materials in response to elevated intraocular pressures may affect the susceptibility of remaining axons to pressure by changing the physical properties of their support tissues, by affecting the support functions of astrocytes and by changing the microenvironment of injured axons. This model may be useful for studying these and other aspects of the process of axonal injury resulting from elevated intraocular pressure.

Animals↗
PubMed1996

Military pregnancies and adverse perinatal outcome.

OBJECTIVE: To identify significant risk factors for an adverse outcome in active-duty military women. METHODS: A prospective study of 105 pregnancies and their outcome. RESULTS: The data revealed that: (1) single women more than married personnel had cesarean births when compared with forceps and vacuum (P < 0.03) or spontaneous vaginal delivery (P < 0.04); and (2) active-duty women who gained < 25 pounds during pregnancy developed preterm labor more often (P < 0.05). CONCLUSIONS: Risk factors for these adverse outcomes remain unknown.

Adult↗
PubMed1996

Prediction of spontaneous preterm birth by fetal fibronectin and uterine activity.

OBJECTIVE: To evaluate the usefulness of fetal fibronectin and home uterine contraction assessment in predicting preterm birth (before 34 weeks) in at-risk asymptomatic women. METHODS: One hundred fifty women were enrolled prospectively; five were lost to follow-up, leaving 145 women available for analysis. Because patients with preterm labor before 34 weeks' gestation most commonly develop this problem after 28 weeks, the period of 26-28 weeks' gestation was selected prospectively as the first window for prediction and study analysis. Eighty-five of 145 asymptomatic women at high risk for preterm birth had both home uterine contraction assessment of 2 hours per day and one or more cervical sampling(s) for fetal fibronectin measurement at 26-28 weeks. A positive home uterine contraction assessment was defined as contractions exceeding two per hour averaged over the 2-week study interval. Positive fetal fibronectin was defined as greater than 50 ng/mL. RESULTS: Fourteen of the 85 women (16.5%) delivered before 34 weeks. Home uterine contraction assessment alone had a sensitivity, specificity, positive predictive value, and negative predictive value for preterm birth of 64, 85, 45, and 92%, respectively; fetal fibronectin alone was associated with values of 43, 89, 43, and 89%, respectively. A positive home uterine contraction assessment was associated with a relative risk (RR) for preterm birth of 5.9% (95% confidence interval [CI] 2.4-14.2), whereas a positive fetal fibronectin demonstrated an RR of 3.8 (95% CI 1.5-9.4). When both assessments were positive, all patients delivered before 34 weeks and there was an RR of 27.0 (95% CI 8.7-84.1) compared with those with both tests being negative. Only two patients with both tests negative delivered before 34 weeks (negative predictive value 96%). CONCLUSION: Both the home uterine contraction assessment and fetal fibronectin accurately predicted preterm birth before 34 weeks. When both tests were combined, the predictive ability improved substantially.

Adult↗