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Biomedical subjects

C Crenshaw

Publications and source records attributed to C Crenshaw.

At least 19 recordsLinked to original sources
PubMed1995

The in-training examination in obstetrics and gynecology: an attempt to establish a remediation indicator.

OBJECTIVE: With the use of a university- and community hospital-based faculty, we attempted to determine at what performance level remediation would be recommended. STUDY DESIGN: The Committee on In-Training Examinations for Residents in Obstetrics and Gynecology Task Force on Standard-Based Scoring sent the 1991 examination to 16 university- and 12 community hospital-based faculty members. Given a standardized definition of a "borderline third-year resident," each faculty scored each item on the examination on whether that hypothetic resident would or would not correctly answer the item. RESULTS: The mean expectation of correct responses on the 397-item test was 236 (59%). This was identical to the score obtained if 2 SDs were subtracted from the actual mean for all third-year residents taking the examination. University- and community hospital-based faculty members had generally similar expectations of this defined resident. CONCLUSION: Although poor examination results should not be recommended as the sole determinant for promotion, it appears that 2 SDs below the mean may be an appropriate score below which remediation could be recommended.

Educational Measurement↗
PubMed1992

Chorionic villus sampling: the University of Maryland experience.

The University of Maryland was the first program in the state to offer chorionic villus sampling (CVS). Since the program's beginning in 1984, 998 patients have been seen with successful sampling in 99.1 percent, using both transcervical and transabdominal approaches. The overall loss rate was quite low (2.3 percent), and no increased risk of birth defects was seen. These observations demonstrate that CVS provides a safe and accurate alternative to amniocentesis.

Abortion, Eugenic↗
PubMed1990

Modulation of mannose receptor activity by proteolysis.

Macrophages express a receptor on the cell surface that functions to clear glycoproteins from the extracellular milieu. The activity of this receptor is sensitive to treatment with trypsin. In inflammatory situations, macrophages are activated and exposed to increased levels of extracellular proteases. Under these conditions, mannose receptor activity on the macrophages is diminished. We therefore decided to study the effects of trypsin treatment on the structure and activity of cell-associated and purified receptor that might contribute to the activation-associated receptor down-regulation. Trypsin treatment (1 microgram/ml for 3 h) resulted in the production of a 140 kDa, trypsin-resistant fragment from both intact cells and isolated receptor. This fragment was no longer able to bind ligand. The remaining 35 kDa fragment apparently is further degraded into smaller fragments, since no evidence of this domain was found on Coomassie Blue-stained gels. The 140 kDa fragment retained immunoreactivity and contained at least a portion of the iodinated tyrosine residues following surface labelling with Na125I. Neither calcium nor ligand protected the receptor from proteolysis. In addition, prior treatment with oxidants did not increase the susceptibility of the receptor to trypsin digestion. We conclude from these results that the macrophage mannose receptor is clipped by the serine protease trypsin at the cell surface, resulting in the release and further degradation of the binding domain, and the production of a membrane-associated 140 kDa fragment. This trypsin-mediated down-regulation of receptor activity might be important in controlling glycoprotein clearance during inflammation.

Animals↗
PubMed1990

Ovarian pregnancy diagnosed after a failed midtrimester therapeutic abortion. A case report.

Ovarian pregnancy is a rare phenomenon. Its presentation often is difficult to distinguish from that of tubal ectopic pregnancy and hemorrhagic ovarian cyst. A patient had an ovarian pregnancy diagnosed following failed midtrimester therapeutic abortion in a suspected bicornuate uterus. Despite vaginal prostaglandin suppositories and intraamniotic instillation of urea and prostaglandin, neither the abortion process nor rupture of the ovarian pregnancy ensued. This is the first reported case of this most unusual presentation of ovarian pregnancy.

Abortion, Therapeutic↗
PubMed1986

Reacting appropriately to thrombocytopenia in pregnancy.

The lower limit of normal for the platelet count is considered to be 150,000/cu mm in both pregnant and nonpregnant normal adults. In the absence of preeclampsia, sepsis, drugs, or other apparent causes, the finding of asymptomatic mild thrombocytopenia in pregnant women is compatible with previously unrecognized immune thrombocytopenic purpura (ITP). Because of the risk of fetal/neonatal thrombocytopenia and the subsequent risk of neonatal intracranial hemorrhage in infants born of mothers with ITP, the optimal mode of delivery for an asymptomatic but thrombocytopenic mother is problematic. Conceivably, those gravidas with mild previously unrecognized thrombocytopenia may not have ITP and thus could be spared cesarean section. From the platelet counts of 730 antepartum patients, we found a mean value of 263,900/cu mm with a standard deviation of 66,000/cu mm, yielding 95% confidence limits of 134,500 to 393,300/cu mm. The distribution is statistically indistinguishable from a normal distribution. Of 26 asymptomatic thrombocytopenic patients with no hematologic history, none had infants with hemorrhage or platelet counts less than 100,000/cu mm. Only one patient subsequently had severe glucocorticoid-resistant thrombocytopenia requiring splenectomy several months after delivery. The remaining patients continue to be asymptomatic to date, with platelet counts greater than 100,000/cu mm. We suggest a plan for managing less than normal platelet counts in asymptomatic gravidas without a history of hematologic abnormality.

Cesarean Section↗
PubMed1984

Antepartum fetal heart rate response to sound stimulation: the acoustic stimulation test.

The fetal heart rate acceleration response to an acoustic stimulation was compared to the traditional nonstress test in regard to pregnancy outcome, as reflected by the incidence of intrapartum fetal distress, meconium staining of the amniotic fluid, 1- and 5-minute Apgar scores, and perinatal mortality. Fetuses with spontaneous or sound-generated reactivity had comparably good outcomes with respect to all outcome measures investigated. Fetuses who lacked spontaneous or sound-stimulated reactivity had an increased risk for intrapartum fetal distress. The acoustic stimulation test is a safe and rapid test of fetoplacental sufficiency that appears to perform comparably to the nonstress test. The acoustic stimulation test significantly shortens total antepartum testing time and expense.

Acoustic Stimulation↗
PubMed1984

Developmental changes in cardiac contractility in fetal and postnatal sheep: in vitro and in vivo.

Developmental changes in contractility were sought in the fetal and postnatal sheep heart by using postextrasystolic potentiation and force, pressure, and wall-motion measures. Two different preparations were used, isolated myocardium and the chronically instrumented lamb. In the isolated muscle, the following increased significantly with age: force of contraction, the maximum rate of rise of force, and postextrasystolic potentiation. In the intact heart prior to birth [period of study, 20 +/- 4 (SD) days] heart rate (HR) fell significantly, and the following increased significantly: postextrasystolic potentiation [measured with the maximum rate of rise of left ventricular (LV) pressure (Pmax)], LV peak systolic pressure (LVP), end-diastolic dimension (EDD), end-systolic dimension (ESD), and aortic diastolic pressure. After birth, LVP, Pmax, HR, LVEDP, EDD, and ESD increased and postextrasystolic potentiation fell. The latter fall was not found in vitro and probably demonstrates a transient change in contractility, related to hormonal or neural stimulation. Over the subsequent postnatal days (6-122 days), HR fell while potentiation, EDD, and ESD increased significantly. Both in vitro and in vivo, the overall increase in postextrasystolic potentiation demonstrates a similar long-term change in contractility. The similarity of this change to that induced by mild hypertrophy suggests that development and mild hypertrophy alter myocardial contractility through a common mechanism.

Animals↗
PubMed1983

Isovolumetric partial exchange transfusion in the management of sickle cell disease in pregnancy. II. Simplified ambulatory technique.

A simple technique is presented for determining the volume of blood to be exchanged in an isovolumetric partial exchange transfusion in order to achieve a desired final hematocrit or desired final percentage of normal hemoglobin. Experience from 16 exchange transfusions in 10 obstetric patients is used to improve the estimate of specific blood volume and, hence, the accuracy of the technique. A detailed protocol for this simple outpatient procedure is presented.

Anemia, Sickle Cell↗
PubMed1983

Prematurity and the obstetrician. A regional neonatal intensive care nursery is not enough.

Modern-day perinatal care has resulted in dramatically improved outcomes of premature infants, particularly those weighing 750 to 1,500 gm or of 27 to 32 weeks' gestational age. Assuming that the birth is not traumatic, the infant asphyxiated, or made hypothermic at birth, the chances of the very small premature baby developing normally are great. The delivery of an infant of less than or equal to 32 weeks' gestational age or weighing less than 1,500 gm should occur at a perinatal center when possible.

Delivery, Obstetric↗
PubMed1983

A prospective random study of a single agent versus combination antibiotics as therapy in penetrating injuries of the abdomen.

One hundred patients undergoing operation for penetrating and potentially contaminated wounds of the abdomen were given cefamandole or a combination of cephalothin-tobramycin by a random, single blind method as preventive therapy. Results were evaluable for 49 patients receiving cefamandole for a success rate of 93.9 per cent. The 45 evaluable results in the second group had a success rate of 88.9 per cent. Those in the single therapy group also required fewer days of treatment and of hospital confinement, resulting in lower per patient cost. Results of this study show cefamandole to be an efficacious alternative for surgeons seeking a single agent therapy.

Abdominal Injuries↗
PubMed1982

The dehydroepiandrosterone loading test. IV. Evaluation of clinical utility.

This report complements the previously described preliminary clinical evaluation of the dehydroepiandrosterone (DHEA) loading test (DLT) by presenting the results of 65 DLTs in 59 patients. In patients whose fetuses were suspected of being intrauterine growth retarded, a DHEA to estrogen conversion rate constant less than or equal to 3.0 x 10(-3) min(-1) was associated with a birth weight below the tenth percentile in 60% of the pregnancies, whereas a conversion rate constant above this threshold was not associated with the same degree of growth retardation. The DLT continues to qualify as an accurate predictor of pregnancy outcome as judged by birth weight. Although it seems to be too cumbersome to serve as a screening technique, the DLT will permit evaluation of the efficacy of various pregnancy interventions directed toward improvement of the intrauterine environment, such as bed rest, tocolysis, or antihypertensive medication.

Birth Weight↗
PubMed1980

Biophysics of the developing heart.

The force-interval relationship was evaluated in the developing heart of the lamb. The qualitative characteristics of the relationship were the same in isolated muscle (from 93 to 141 days' gestation to 1 year old) as in the chronically instrumented in utero fetus (122 to 141 days' gestation): (1) contractility, e.g., the maximum rate of rise of force, increased monotonically from a small value immediately after a contraction to a plateau, and (2) postextrasystolic potentiation was present in all preparations. In the intact animal, postextrasystolic potentiation depended on the basic pacing interval, t0, and the timing of the extrasystole, t1: when t0 was held constant and t1 was increased, potentiation decreased; when t1 was held constant and t0 was increased, potentiation increased. The qualitative characteristics of the relationship, and so the underlying myocardial basis, were unchanged over the developmental period studied.

Animals↗
PubMed1980

Biophysics of the developing heart. II. The interaction of the force-interval relationship with inotropic state and muscle length (preload).

The interaction of the force-interval relationship, muscle length (ventricular volume), and inotropy was evaluated in isolated fetal myocardial preparations and in the in utero chronically instrumented fetal lamb. In the isolated muscle, 93 to 141 days' gestation, a change in muscle length strengthened all contractions equally (multiplicatively) but produced no other changes in either the quantitative or the qualitative characteristics of the force-interval relationship; it was significantly altered by isoproterenol. Similarly, in the intact fetal lamb the qualitative and quantitative features of the relationship did not depend on ventricular volume, e.g., postextrasystolic potentiation was constant over a wide range of volumes. But isoproterenol produced a decrease in postextrasystolic potentiation. These results demonstrate that the force-interval relationship satisfies two major criteria for an index of cardiac contractility and suggest that the relationship may provide a basis for the evaluation of changes in contractility with development and birth.

Animals↗
PubMed1980

Fetal lamb lung phosphatidylcholine: response to asphyxia and recovery.

Acute fetal asphyxia resulting from maternal blood loss and hypotension causes a reduction in the incorporation of precursors into disaturated phosphatidylcholine, the principal lipid in the pulmonary surfactant. Treatment of the maternal hypotension is associated with return of fetal lung DSPC synthesis to control levels by 72 hours.

Acidosis, Respiratory↗
PubMed1979

The dehydroepiandrosterone loading test. III. A possible placental function test.

The dehydroepiandrosterone loading test (DLT) has been used in a small population of normal and high-risk obstetric patients, to date, in an attempt to develop a dynamic test of placental function. In spite of its limited applications, it has shown reliability in discriminating, with statistical significance, between high-risk pregnancies that result in normally grown, undistressed infants, and high-risk pregnancies that result in infants showing signs of placental insufficiency. The present report expands the study population by presenting our data on 40 loading tests performed in 37 high-risk and normal obstetric patients. Results of 19 of these DLT's have been previously reported and are included herein for statistical analysis. The DLT utilizes an excess substrate load of dehydroepiandrosterone to assess the maximum capability of the placenta to convert it to estrogen. Although our previous report did not show false positive or negative results in the conversion rates, the present results (40 DLT's) found two (2 out of 17) false positives (12%) and two (2 out of 19) false negatives (11%). The highly significant correlation between DLT result and pregnancy outcome seen previously was preserved. In addition, the data of another five DLT's in four patients are presented. This group includes a pregnancy with a fetus with multiple congenital malformations, two patients with intrauterine fetal death, and a nonpregnant woman. The results are not included in the statistical analysis, but discussion of these results has interesting pathophysiologic implications.

Dehydroepiandrosterone↗
PubMed1979

O2 delivery to the pregnant uterus: its relationship to O2 consumption.

Normal sheep were studied at intervals of 3-5 days during the last weeks of pregnancy in order to evaluate variability in rate of O2 consumption (QO2) of the uterus in relation to several variables involved in delivery of O2 to the organ. Among-animal differences of uterine QO2 were statistically significant and directly related to birthweight of the lamb. Among-animal differences of uterine blood flow (UBF) and uterine arteriovenous O2 content difference [C(a-v)O2] also were statistically significant, though neither was related to birthweight, presumably since they tended to vary inversely with one another. In a given ewe relative magnitude of UBF and of C(a-v)O2 was related to maternal arterial O2 content (CaO2), day of pregnancy, and whether the animal carried singlets or twins. Variability in QO2 was most closely related to UBF, although its relations to C(a-v)O2 and CaO2 were significant also. These data suggest there are systematic relationships among variables involved in the delivery of O2 to the uterus of pregnant sheep.

Animals↗