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Biomedical subjects

M C Crenshaw

Publications and source records attributed to M C Crenshaw.

At least 19 recordsLinked to original sources
PubMed1999

Slow-wave sleep and waking cognitive performance among older adults with and without insomnia complaints.

Previous research has shown that healthy young adults with relatively fast reaction times on daytime testing have significantly more nocturnal slow-wave sleep than do age-matched subjects with relatively slow reaction times on such testing. The current study was conducted to examine the relationship between slow-wave sleep and cognitive performance among older adults with and without insomnia complaints. A sample of 32 noncomplaining older (age > or = 60 years) normal sleepers and a like-aged sample of 32 insomniacs, recruited to participate in a larger study, served as subjects. All subjects underwent nocturnal sleep monitoring immediately prior to undergoing a battery of daytime tests that measured simple reaction time, vigilance/signal detection, and complex reaction time. Results from the normal sleepers showed no relationship between daytime cognitive performance measures and a variety of computer-derived nocturnal slow-wave sleep measures. In contrast, insomniac subjects with relatively slow reaction times showed relative deficits in a spectral analytically derived measure of slow-wave power in the 2 to 4 Hz bandwidth. These results suggest that relative performance deficits among some older insomniacs may be related to specific slow-wave sleep deficiencies. However, among older normal sleepers, intersubject differences in performance appear unrelated to slow-wave sleep measures. Additional research is needed to further explore the possible restorative role slow-wave sleep may serve for cognitive functions other than those examined herein.

Aged↗
PubMed1993

The fourth-year medical school curriculum: recommendations of the Association of Professors of Gynecology and Obstetrics and the Council on Resident Education in Obstetrics and Gynecology.

OBJECTIVES: The Association of Professors of Gynecology and Obstetrics and the Council on Resident Education in Obstetrics and Gynecology have proposed a fourth-year medical school curriculum for a student interested in pursuing a residency in obstetrics and gynecology. STUDY DESIGN: Faculty members and residents in North Carolina, Illinois, and Michigan were surveyed as to the ideal curriculum that they would recommend for fourth-year students. The committee members representing the Council on Resident Education in Obstetrics and Gynecology and the Association of Professors of Gynecology and Obstetrics then reviewed these surveys and proposed a final curriculum. RESULTS: A core curriculum of general medicine as an acting internship, an intensive care unit rotation, neonatology, and emergency medicine was recommended. Additional courses strongly considered were ambulatory obstetrics-gynecology, acting internship in obstetrics-gynecology, endocrinology, and general surgery. CONCLUSION: The committee recommends a curriculum that is broad and balanced in general medical education.

Curriculum↗
PubMed1991

An antigen immunologically related to the external domain of gp185 is shed from nude mouse tumors overexpressing the c-erbB-2 (HER-2/neu) oncogene.

An antigen, immunologically related to the external domain of the c-erbB-2 (HER-2/neu) protein, was found shed into the serum of nude mice bearing tumors that overexpress the c-erbB-2 protein (gp185). Utilizing paired combinations from a panel of monoclonal antibodies (TAbs 250-265), with specificity for extracellular epitopes of gp185, an immunoradiometric assay was developed to quantitate this shed antigen. The immunoradiometric assay detected membrane-bound and soluble gp185 as well as a soluble derivative corresponding in sequence to the extracellular domain of gp185 (designated gp75). This recombinantly expressed gp75 was immunoaffinity purified and used to generate a standard curve from which serum samples were quantitated. Increases in antigen levels measured in the sera of tumor-bearing nude mice correlated with both overexpression of the c-erbB-2 protein and increased tumor volume. Positive sera were obtained from mice given implants of NIH3T3 cells transfected with c-erbB-2 complementary DNA (NIH3T3t), or ovarian (SK-OV-3) or breast (MDA-MB-361) tumor cell lines overexpressing the c-erbB-2 protein. In mice bearing NIH3T3t tumors, increases in tumor volume from 80 to 9000 mm3 resulted in levels of shed antigen from 8 to greater than 1000 ng/ml gp75 equivalents. Sera from mice with c-erbB-2-negative tumors or tumors overexpressing the epidermal growth factor receptor were negative in the assay. This assay, and the quantitation of shed antigen levels, may have diagnostic or monitoring utility in cancers, such as breast and ovarian, in which the c-erbB-2 protein is overexpressed.

Animals↗
PubMed1990

Tocolysis in the management of third trimester bleeding.

Fifteen patients were identified in a retrospective analysis of one institution's experience with the use of tocolysis in selected patients with an admission diagnosis of placenta previa or abruptio placentae. There were no fetal deaths after admission, and the two neonatal deaths were related to prematurity. Eight of the 15 patients receiving tocolysis had their pregnancies prolonged by 2 weeks or more, and there were no fetal or neonatal deaths in this group. Both neonatal deaths occurred in patients who underwent tocolysis but who gave birth within 1 day of admission. These data suggest the safety of tocolysis in preterm patients with the diagnosis of placenta previa or abruption who are bleeding. A prospective, randomized trial is required to evaluate whether tocolysis is superior to expectant management or to immediate delivery. The clinical difficulty in differentiating between these two diagnoses, despite liberal use of ultrasonography, is discussed.

Abruptio Placentae↗
PubMed1989

The effect of estrogen on placental delivery after fetectomy in baboons.

In baboons, the placenta remains in situ and functional with respect to the potential for aromatization after removal of the fetus (fetectomy). Fetectomy therefore was used to study effects of the fetus and estrogen on placental delivery. By term, serum estradiol levels in untreated, intact baboons had increased to 4 to 8 ng/ml, and fetoplacental delivery occurred on day 184 +/- 1 (mean +/- SE). Fetectomy at midgestation resulted in a nondetectable serum estradiol level and a marked decline in progesterone level; however, placentas were maintained in situ and were delivered on day 171 +/- 6. After fetectomy therefore the initiation of placental delivery and, presumably, myometrial contractility did not require an elevation in estrogen. Administration of estradiol (1 to 10 mg/day) to baboons after fetectomy resulted in normal serum estradiol concentrations, but placental delivery was prevented. When estrogen was discontinued on days 215 to 250, the serum estradiol level declined, and placental delivery occurred on day 262 +/- 18, a value greater than in intact baboons or untreated baboons after fetectomy (p less than 0.001). Thus estrogen prevented placental delivery in baboons after fetectomy.

Animals↗
PubMed1988

The association of Chlamydia trachomatis, Neisseria gonorrhoeae, and group B streptococci with preterm rupture of the membranes and pregnancy outcome.

There is conflicting evidence regarding a possible causal role for Chlamydia trachomatis in the development of preterm premature rupture of the membranes. We investigated the relative prevalence of endocervical infection with C. trachomatis and group B streptococci in patients with preterm premature rupture of membranes compared with a control group taken from the same obstetric population. C. trachomatis was isolated from 23/52 (44%) patients with preterm premature rupture of membranes versus 13/84 (15%) women in the control group (p less than 0.001). This association was independent of infection with group B streptococci or Neisseria gonorrhoeae. Group B streptococci were isolated from 16% of the patients with preterm premature rupture of membranes versus 4% of the control population (p less than 0.05). The risk of preterm premature rupture of membranes associated with group B streptococcal infection was independent of infection with C. trachomatis and N. gonorrhoeae. Endocervical infection with C. trachomatis did not significantly affect early maternal complication rates after delivery.

Adult↗
PubMed1988

Conservative management of placenta accreta. A case report.

Placenta accreta is a rare complication of pregnancy. Traditional therapy has centered upon total abdominal hysterectomy to prevent serious hemorrhagic and infectious sequelae. Conservative management, however, may preserve reproductive function without jeopardizing maternal welfare.

Adult↗
PubMed1982

Pulmonary complications of isoxsuprine therapy in the gravida.

The potential association of intravenous isoxsuprine therapy for premature labor with pulmonary edema and an adult respiratory distress syndrome is demonstrated by 6 patients, 3 of whom became critically ill. While other tocolytic agents have been associated with pulmonary edema, most commonly when used in combination with glucocorticoids, this is the first report of maternal pulmonary complications from isoxsuprine therapy, both with and without associated glucocorticoid administration. A case of right middle lobe pneumonia that bore a temporal proximity to maternal isoxsuprine and betamethasone therapy is also presented. No explanation of these associations is offered. All these cases occurred in 1977. The utilization of isoxsuprine at the authors' institution has not changed since then, either in frequency or protocol, nor has the drug formulation been changed, yet no comparable complications have been seen since. This phenomenon is not understood.

Adolescent↗
PubMed1981

Stimulation by ornithine of ovine placental lactogen secretion.

Arginine is a potent stimulus to the secretion of placental lactogen (PL) as well as GH and prolactin in sheep. To determine whether other amino acids of the urea cycle also affect PL secretion, ornithine (25 g) and citrulline (20 g) were infused intravenously into four pregnant ewes over a period of 0.5 h. In eight experiments, ornithine stimulated PL secretion by 124 +/- 25 (S.E.M.) % with the initial increase occurring by 1 h after the start of each infusion. Plasma GH concentrations increased from 3.4 +/- 1.1 to 24.5 +/- 5.9 ng/ml and plasma prolactin concentrations increased from 58.8 +/- 12.8 to 310.7 +/- 88.4 ng/ml. Citrulline, on the other hand, had no consistent effect on PL secretion. Plasma GH concentrations following the infusion of citrulline, however, increased by 15-20 ng/ml in two of four experiments and plasma prolactin concentrations decreased by 73.2 +/- 3.2% in all four experiments. The results indicate that ornithine is also a potent stimulus to the secretion of PL, GH and prolactin and suggest that arginine-induced PL secretion may result from the conversion of arginine to ornithine.

Animals↗
PubMed1981

The effects of prophylactic management and therapeutics on hypertensive disease in pregnancy: preliminary studies.

A controlled prospective evaluation of pregnancy complicated by chronic hypertension is proposed and preliminary data on population selection and pregnancy outcome are presented. Sixty-three women with evidence of underlying hypertensive disease were followed prospectively throughout pregnancy. Twenty-three patients were followed in a protocol of intensified prenatal care and randomized assignment of antihypertensive agents: placebo, hydralazine, or methyldopa. Forty patients were followed in the high-risk pregnancy clinics at Duke University. The incidence of preeclampsia in the randomized prophylactic antihypertensive group was statistically lower than that in the nonrandomized group (8.7 versus 32.5%; P less than .01). There were no other statistically significant differences between the groups. The 63 hypertensive women had a high incidence of diabetes mellitus diagnosed during pregnancy (49.2%) as compared to the authors' general obstetric population (8.1%).

Adult↗
PubMed1980

Premature rupture of the membranes: maternal and neonatal infectious morbidity related to betamethasone and antibiotic therapy.

A retrospective study of patients delivering in 1976-77 at Duke University Medical Center was performed to assess the impact of betamethasone and prophylactic antibiotics on infectious morbidity in mothers with premature rupture of the membranes (PROM) at 26 to 34 weeks' gestation and in their neonates. Ninety-five records were reviewed for evidence of maternal and neonatal infection and perinatal mortality. Betamethasone had no impact on maternal or neonatal infection. Antibiotics given concurrently with betamethasone significantly reduced the incidence of maternal and/or neonatal infection (18.0% vs. 0). Perinatal mortality increased when the duration of the latent period was 72 hours and greater because of factors other than infection.

Anti-Bacterial Agents↗
PubMed1979

Hemoglobin A1c in normal and diabetic pregnancy.

The usefulness of determining hemoglobin A1c (HbA1c) levels during pregnancy was evaluated. In contrast to previous reports, the HbA1c values did not predict abnormal maternal glucose tolerance or infant birth weight. They did, however, correlate with long-term control of the diabetes of pregnant insulin-dependent patients. The slight decrease in HbA1c values observed as pregnancy advanced was secondary to improved control of diabetes.

Birth Weight↗
PubMed1978

Amniotic fluid cortisol in normal and diabetic pregnant women and its relation to respiratory disease in the neonate.

One hundred and thirty samples of amniotic fluid from normal and diabetic pregnant women were analyzed for cortisol concentration. In normal pregnancies, cortisol was present in low concentrations until 35 weeks' gestation, followed by a sharp rise at 36 weeks and a continued upward trend to 39 weeks. The rise after 35 weeks was delayed or absent in many patients with diabetes. In the combined population, the incidence of respiratory disease with a lecithin/sphingomyelin ratio greater than or equal to 2 was 26 per cent if the amniotic fluid cortisol was less than 4.3 microgram per 100 ml. and 2.9 per cent if the cortisol concentration was greater than or equal to 4.3 microgram per 100 ml.

Amniotic Fluid↗
PubMed1978

Concurrent hypertension and pregnancy.

Concurrent hypertension in pregnancy alters the diagnosis and prognosis of both the vascular disease and the gestation. Insight into the physiologic and pathophysiologic changes is essential to assessing the patient's status and to determining what antenatal care may yield the best outcome of the pregnancy. In this monograph we have presented (1) a classification, which correlates well with those currently in use, of the types of hypertension and their causes; (2) a brief review of current fact and theory regarding the effect of hypertension on maternal and perinatal morbidity and mortality; (3) a detailed approach to monitoring the physical and laboratory parameters of the parturient; (4) a rational approach to monitoring the fetoplacental unit; and (5) an analysis of currently available therapeutic regimens that may alter the course of hypertension in pregnancy sufficiently to increase fetal salvage and decrease maternal complications. Certainly more research into the mechanisms of CHP will be forthcoming as will newer and more precise diagnostic aids. Pharmacologic agents with varied hypotensive actions are constantly being developed, and combinations of these may yield more beneficial results.

Amniotic Fluid↗
PubMed1978

Significance of biparietal diameter differences between twins.

Twins of dissimilar size have increased risks both at delivery and in the neonatal period. When dissimilar growth is severe, it should be reflected in birthweight and biparietal diameter (BPD) growth. Sonograms were done on 74 of 106 sets of twins delivered from July 1, 1973, to June 30, 1977. Excluding prematurity and birth trauma, the difference in BPD between twins with normal outcomes in the last scan prior to delivery was 1.32 +/- 0.20 mm (mean +/- SE) and the difference in birthweight was 250.3 +/- 31.4 g (mean +/- SE). In 7 sets of twins with poor outcomes (intrauterine fetal demise or severe intrauterine growth retardation) without central nervous system anomalies the difference in BPD between twins in the last scan, while both fetuses were alive, was 6.86 +/- 1.06 mm (mean +/- SE) and the difference in birthweight was 604.3 +/- 217.2 g (mean +/- SE). Both the BPDs and birthweights are significantly different at the P less than 0.01 level. Large differences in BPD between twins may possibly indicate compromise of one twin.

Female↗
PubMed1978

Stimulation of ovine placental lactogen secretion by arginine infusion.

Arginine has been demonstrated to be a potent stimulus to GH and PRL secretion. To determine the effect of arginine on plasma ovine placental lactogen (oPL) concentrations, arginine (50 g in 350 ml distilled water, pH 7.4) or hypertonic saline of identical volume, osmolality, and pH was infused iv over a 30-min period into nine pregnant ewes, and blood samples from chronic indwelling venous catheters were obtained at frequent intervals before and for 8 h after the infusions. After the infusion of hypertonic saline, plasma oPL concentrations (measured by homologous RIA) decreased 20--50% over 1--2 h and then returned to baseline concentrations. After the infusion of arginine, plasma oPL concentrations also decreased by 20--50% for 1--2 h. However, 2--3 h after the infusion, plasma oPL concentrations in creased 79--115% (delta = 204--700 ng/ml) over preinfusion concentrations in seven ewes and 454% (2930 ng/ml) and 1142% (2042 ng/ml) in two ewes and remained elevated for the remainder of the 8-h interval. When the amount of arginine infused was reduced from 50 to 25 g, an increase in plasma oPL concentrations occurred in only one of five ewes. Plasma oPL concentrations increased by 8--58% after infusions of 50 g alanine or glycine but did not increase after 50 g glutamic acid. The delayed oPL response to arginine suggests that the increase in plasma oPL concentrations is not caused directly by arginine but rather by changes in the synthesis, secretion, and/or degradation of oPL induced indirectly by arginine.

Animals↗