Biomedical subjects

B D Cowan

Publications and source records attributed to B D Cowan.

At least 37 records · Page 2Linked to original sources

PubMed1996

Estimating birth weight in twins. Comparison of eight sonographic models.

OBJECTIVE: To establish the relative accuracy of eight sonographic models that use one to four fetal biometric measurements to derive birth weight in twin pregnancies. STUDY DESIGN: Over three years, 181 twin gestations with sonographic mensuration of biparietal diameter, head circumference, abdominal circumference (AC) and femur length (FL) within 96 hours of delivery were analyzed. Analysis of variance followed by Student-Newman-Keul's test was used to determine the relative accuracy of the eight models. A receiver-operating characteristic (ROC) curve was constructed to determine the sonographic estimate that would consistently identify a nonvertex twin B with a birth weight of < or = 1,500 g. RESULTS: The mean gestational age was 32.4 +/- 4.3 (SD) weeks, and the mean birth weights for twins A and B were 1,851 +/- 676 and 1,883 +/- 655 g, respectively. For both fetuses, the mean standardized absolute error was significantly higher for estimates based on one fetal parameter (AC or FL). Regardless of presentation (A or B, vertex or nonvertex) or whether the actual birth weight was < or = 1,500 or > 1,500 g, accuracy was similar between the six models that used two or more fetal parameters to predict the newborn's weight. ROC analysis revealed that among nonvertex twins B, an estimate of birth weight (based on BPD and AC or AC and FL) < or = 1,700 g will consistently identify the newborn with a birth weight < or = 1,500 g. CONCLUSION: Sonographic models that use two fetal parameters are adequate for assessing birth weight in twin gestations regardless of position or if the birth weight is < or = or > 1,500 g.

Adult↗

PubMed1996

Intrapartum amniotic fluid index. A poor diagnostic test for adverse perinatal outcome.

OBJECTIVE: To determine if an intrapartum amniotic fluid index (IAFI) < or = 5.0 cm, or any other level, is associated with abdominal delivery for fetal intolerance to labor or Apgar scores < 7 at one and five minutes. STUDY DESIGN: Prospectively IAFI was obtained in the latent phase of labor in 1,000 parturients at > 26 weeks. Receiver operating characteristic curves were utilized to determine if any IAFI could be utilized to predict adverse outcome among (1) the entire population, (2) complicated pregnancies, (3) uncomplicated pregnancies, (4) term, or (5) preterm gestation. RESULTS: The frequencies of abdominal delivery for suspected fetal intolerance and low Apgar scores were similar among patients with IAFI < or = 5.0 cm (n = 288) versus those with IAFI > 5.0 cm. All five receiver operating characteristic curves indicated that IAFI is a poor predictor of adverse outcomes. At all the discriminatory IAFIs (0-20 cm), the false positive rate was virtually identical to the true positive rate. CONCLUSION: IAFI appears to be a poor screening test for identifying those at risk for abdominal delivery for presumed fetal distress or for birth of an infant with low Apgar scores.

Amniotic Fluid↗

PubMed1995

One artificial insemination per cycle with donor sperm is as efficacious as two inseminations.

PURPOSE: To compare pregnancy rates per treatment cycle of artificial inseminations with donor sperm in patients receiving one versus two inseminations. METHODS: Retrospective cross-sectioned analysis of 167 patients who underwent 869 cycles receiving one or two donor inseminations were reviewed from 1987 through 1993 at our institution. RESULTS: A total of 256 cycles with one donor insemination per cycle resulted in 21 pregnancies and a cycle of fecundity of 8.2%, and 613 cycles with two donor inseminations resulted in 35 pregnancies and a cycle fecundity of 5.7%. Life table and logistic cumulative probability analysis of pregnancy occurrence showed no difference between treatment groups. CONCLUSIONS: These data suggest there are no important clinical differences of cycle fecundity or cure rate in one versus two inseminations with donor sperm. Economic costs of two inseminations may not be justified.

Cross-Sectional Studies↗

PubMed1995

Progesterone concentration as a predictor of pregnancy normalcy is the most useful when hCG levels are less than 2000 mIU/mL.

OBJECTIVE: Measurements of serum progesterone to predict early gestational normalcy have been found to be as predictive as serial hCG titers. Since ultrasound would be the diagnostic tool of choice if hCG was > 2000 mIU/ml, the purpose of the present study was to determine the best predictive value of a single progesterone measurement when hCG levels were < 2000 mIU/ml. DESIGN: Relative operating characteristic analysis of progesterone level as a predictor of early gestational normalcy when hCG is < 2000 mIU/ml. MATERIALS AND METHODS: Ninety-three pregnant patients that conceived spontaneously were evaluated with progesterone measurements when the patient's hCG was < 2000 mIU/ml. Two-by-two contingency tables were constructed that compared pregnancy outcome with multiple discriminatory serum progesterone concentrations between 0 and 38 ng/mL. From these tables, a relative operating characteristic (ROC) curve was generated to compare the sensitivity and false-positive rates. RESULTS: Of a total of 93 pregnancies, 27 had a normal outcome and 66 had an abnormal outcome. The ROC curve indicated that a serum progesterone concentration of 12 ng/ml had the highest sensitivity associated with the lowest false-positive rate. The area under the curve was equal to 0.941 +/- 0.024. This observation was compared to our previously reported data of progesterone levels that included hCG levels > 2000 mIU/ml, yielding an area under the curve of 0.772 +/- 0.053. Calculation of the critical ratio z revealed that there is a significant improvement in the predictive value of progesterone when hCG is < 2000 mIU/ml (P < 0.005). CONCLUSION: A single serum progesterone level has a better predictive value of pregnancy normalcy when hCG measurements are < 2000 mIU/ml.

Chorionic Gonadotropin↗

PubMed1995

Elevated luteinizing hormone on the day of human chorionic gonadotropin administration does not reduce cycle fecundity in a low-dose flare-up in vitro fertilization protocol.

OBJECTIVE: To determine if elevated LH at the time of hCG administration occurs and adversely affects success in a low-dose gonadotropin-releasing hormone analogue (GnRH-a) flare-up protocol in hMG-stimulated IVF cycles. DESIGN: Pearson correlation matrix analysis of hormonal, gamete, and clinical data derived from 203 consecutive IVF cycles was performed. All patients were treated with low-dose GnRH-a (250 micrograms SC leuprolide acetate) and hMG. In 203 consecutive IVF cases, serum was obtained on the day of hCG administration and assayed for E2, LH, and P. These data were correlated with peak E2, number of follicles, oocytes, embryos, and conceptions. Additionally, patients with elevated LH were compared with the nonelevated LH group. RESULTS: Twenty six women had LH > 35 mIU/mL (mean +/- SEM; 51.1 +/- 1.9) and five pregnancies (cycle fecundity 19.2% per retrieval). One hundred seventy-seven patients had LH < 35 mIU/mL (16.3 +/- 0.5) and 25 pregnancies (cycle fecundity 14.1%). There were no differences in the mean P (1.0 +/- 0.1 ng/mL, conversion factor to SI unit, 3.81) and E2 (1,672 +/- 144 pg/mL, conversion factor to SI unit, 3.671) of the former group compared with the P (1.1 +/- 0.07 ng/mL) and E2 (1,456 +/- 69 pg/mL) of the latter group. There was no correlation with the number of follicles, oocytes, embryos, pregnancies, E2, or P to LH concentration (rmax = 0.132). CONCLUSION: In a low-dose, GnRH-suppression, IVF induction protocol, elevated LH occurs in a small subset (13%) of women at the time of hCG administration. This event does not appear to alter cycle fecundity nor induce premature luteinization.

Chorionic Gonadotropin↗

PubMed1995

Luteal phase consequences of low-dose gonadotropin-releasing hormone agonist therapy in nonluteal-supported in vitro fertilization cycles.

OBJECTIVE: To determine the follicular and luteal phase impact of low-dose GnRH agonist (GnRH-a) treatment during follicular stimulation for IVF. DESIGN: A randomized prospective study compared patients receiving low-dose GnRH-a and hMG therapy to clomiphene citrate (CC) and hMG cycles. SETTING: Patients were treated through a university-based IVF-ET program. PATIENTS: Thirty-six patients underwent follicular stimulation with low-dose GnRH-a and hMG and were compared with 34 patients undergoing ovulation induction with CC and hMG. RESULTS: Significantly shorter luteal phase length occurred with GnRH-a and hMG therapy; however, there was no statistically significant difference in luteal P levels. Follicular parameters were the same (peak E2, number of follicles, and number of oocytes), suggesting that folliculogenesis was not altered. There were no statistical differences in pregnancy rates. CONCLUSIONS: Sustained low-dose GnRH-a therapy during follicular stimulation does not have a clinical effect on luteal function.

Clomiphene↗

PubMed1995

Intrapartum detection of a macrosomic fetus: clinical versus 8 sonographic models.

The purpose of this study was to determine whether clinical or sonographic models have 1) the highest accuracy in differentiating newborns with birth-weights > or = 4,000 g (macrosomia) versus < or = 3,999 g, and 2) among macrosomics which method of predicting birth-weight has the lowest percentage error. Prospectively, 602 consecutive parturients at term had a clinical estimate of birth-weight followed by sonographic measurement of fetal parts. The sonographic prediction of birth-weight was derived using 8 different models that utilize either 1 measurement or a combination of 2 to 4 parameters. The incidence of macrosomia was 11.1% (67 of 602). Analysis of ROC curves indicated that clinical predictions (w = 0.85) were significantly better than 4 of the 8 sonographic models. The mean standardized absolute error among macrosomic newborns is significantly lower when predictions are derived clinically (99 +/- 70 g/kg) than using 1 or 2 fetal parts. Sonographic assessment of birth-weight is not significantly more accurate in the detection of a macrosomic fetus than clinical predictions.

Adult↗

PubMed1995

Immunosuppression by conditioned media derived from a cloned choriocarcinoma cell line in serum-supplemented and defined media.

PROBLEM: Immunosuppressive factor(s) of trophoblast origin may contribute to the immunological privilege afforded the fetal allograft. Characterization of these immunoregulators in humans has been impeded by a lack of sufficient quantities of early gestational trophoblast for experimentation. METHOD: In this study, a cloned choriocarcinoma cell line (BeWo) was evaluated as an experimental model of trophoblast-derived immunoregulation. BeWo cells were cultured in both serum-supplemented (15% fetal bovine serum; FCS-CM) and serum-free (10% bovine serum albumin, BSA-CM; 0.01% gelatin, Gel-CM) media. Immunosuppressive activity was determined through the use of interleukin-2-dependent (CTLL-2) and -independent (LBRM) cell lines. Human chorionic gonadotropin (hCG) levels were determined by an immunoradiometric assay, and cellular morphology was assessed by light microscopy. RESULTS: In the serum-supplemented cultures, a portion of cells underwent transformation from single nucleated cytotrophoblast to multinucleated syncytiotrophoblast during days 1 to 5 of culture and was accompanied by a rise in hCG. Serum-free cultures were characterized as islands of cytotrophoblast and did not exhibit differentiation. FCS-CM suppressed CTLL-2 and LBRM proliferation with estimated EC50 values of 415 and 280 micrograms protein/mL, respectively. Gel-CM suppressed CTLL-2 and LBRM proliferation with EC50 values of 12 and 7 micrograms protein/mL, respectively. BSA-CM suppressed CTLL-2 proliferation with an EC50 of 132 micrograms protein/mL, but failed to suppress LBRM proliferation below 50% of control. CONCLUSION: These results suggest that the BeWo cell line is a promising model for the study of trophoblast-derived suppressive factors and that these factors can be generated in serum-free medium.

Animals↗

PubMed1995

Intrapartum amniotic fluid index for predicting fetal acidemia. Results of receiver operating characteristic curve analysis.

OBJECTIVE: The objective of this study was to determine if the discriminatory intrapartum amniotic fluid index can reliably predict respiratory or metabolic acidosis in the newborn. STUDY DESIGN: Among 256 parturients at 37 weeks' gestation or more, the intrapartum amniotic fluid index was obtained in early labor, and umbilical arterial blood gas analysis was performed within 30 minutes of delivery. The mean (+/- SD) amniotic fluid indices in labor among newborns with no acidosis versus those with respiratory or metabolic acidosis were compared. A receiver operating characteristic curve was used to determine the best discriminatory intrapartum amniotic fluid index for respiratory and metabolic acidosis. RESULTS: Statistical analysis revealed that the mean intrapartum amniotic fluid index among 12 newborns with respiratory acidosis and 26 with metabolic acidosis was significantly lower than the mean index in 218 newborns without fetal acidemia. Despite the differences in the mean intrapartum amniotic fluid index in the three groups analyzed, the receiver operating characteristic curve indicated that an intrapartum amniotic fluid index alone is a poor test for predicting acidosis (respiratory or metabolic) in the neonate. CONCLUSION: The mean intrapartum amniotic fluid index in labor among newborns with respiratory or metabolic acidosis was significantly lower than that among nonacidotic newborns. The receiver operating characteristic curve indicated that the intrapartum amniotic fluid index cannot reliably distinguish nonacidotic infants from those with respiratory or metabolic acidosis.

Acidosis↗

PubMed1995

Laparoscopically directed ovarian cystectomy in premenopausal women. Impact of surgical experience on surgical time.

The purpose of this study was to correlate surgical experience with operating efficiency. A retrospective review of 303 operative laparoscopic procedures was performed during a 48-month interval and during the acquisition of surgical skills by one faculty member. Population demographics and surgery time were evaluated in 41 cases (13.5%) of ovarian cystectomy. Patients were categorized into fertility-related or gynecologic indications for surgery. Surgical time for successful laparoscopically directed resection of benign ovarian cysts was significantly reduced over the study interval (P = .008). Endometrioma was the most common pathologic finding in women with impaired fertility, and benign epithelial tumors were the lesion encountered most commonly in gynecologic patients. Benign teratoma occurred infrequently in both groups. No malignancy was observed in this group of premenopausal women, who had unilocular cysts less than 8 cm in diameter. Reduction in surgical time for laparoscopically directed ovarian cystectomy occurs after experience is gained by repeated application of the technique.

Adult↗

PubMed1994

Resident research projects: frequency of presentation and publication in a national forum.

OBJECTIVE: Our aim was to determine the fate of mandatory resident research projects with regard to subsequent presentation and publication. STUDY DESIGN: In this retrospective descriptive study required research projects were assessed for frequency of presentation at regional and national meetings or publication in medical journals, or both, over a 10-year period (1983 through 1992). Rising second-year house officers elected to initiate their own study with departmental support under the guidance of a faculty advisor or selected a research project from a list of potential investigations offered by departmental faculty. Projects were presented at the annual alumni meeting in April of the junior and senior years. The faculty advisor assisted in research design, protocol development, obtaining human investigation committee approval, data collection, statistical analysis, manuscript preparation, and coaching for the oral presentation. After local presentation these projects were evaluated for submission to regional and national meetings and prepared for peer-review publication. RESULTS: During a 10-year period 104 resident research projects resulted in 72 regional or national presentations and 52 peer-review publications. There was a significant increase in the proportion of projects presented at national meetings over time (r = 0.99; p < 0.0001). There was also an increase in the number of projects published in peer-review journals during the decade-long study period (r = 0.96, p = 0.0001). CONCLUSIONS: Required completion of two research studies during residency bolstered by early selection of prospective projects and departmental fiscal support, as well as intensive faculty advisor direction and assistance, has resulted in resident projects with increasingly frequent national recognition.

Humans↗

PubMed1994

Serum progesterone predicts abnormal gestations in clomiphene citrate conception cycles as well as in spontaneous conception cycles.

OBJECTIVE: To determine if a "discriminatory" P concentration could be established that predicted abnormal early pregnancies in clomiphene citrate (CC)-conceived cycles. DESIGN: Progesterone concentrations of gestations between 28 and 49 days from last menstrual period in both spontaneously conceived and CC-stimulated cycles were analyzed using a relative-operating characteristic (ROC) curve. INTERVENTIONS: Serum P concentrations were measured in 222 pregnant patients from the first 49 days of gestation. One hundred sixteen patients conceived in a spontaneous cycle and 106 patients conceived in CC-treated cycles. Two by two contingency tables were used to calculate the true-positive (sensitivity) and false-positive rates at 20 specific P at 20 specific P concentrations. A ROC curve was then generated by plotting the sensitivity of the test against the percent of normal patients incorrectly classified (false positive) at each P level. The best discriminatory value was estimated in each curve at a point of high sensitivity associated with a minimal false-positive value. The areas under the curve and SE were calculated for each group and compared by the critical ratio z-test. RESULTS: The best discriminatory P concentration was 10 ng/mL (32 nmol/L) for spontaneously conceived pregnancies and 30 ng/mL (95 nmol/L) for CC-treated pregnancies. The area under each ROC curve was significantly predictive. Comparison of the two curves indicated that the ability of P measurements to predict gestational complications was independent of follicular stimulation. CONCLUSIONS: Follicular stimulation with CC increases the discriminatory P value that predicts gestational normalcy but does not alter the clinical utility of the test.

Abortion, Spontaneous↗

PubMed1994

Regulation of early gestational corpus luteum function in spontaneous and follicular stimulated conceptions.

OBJECTIVE: To determine the regulatory role of hCG on P secretion in normal and abnormal (abortive and ectopic) first trimester pregnancies. STUDY DESIGN: The number of doublings of hCG per day (1/DT; reciprocal of hCG doubling time) was correlated with serum P using linear and nonlinear models in normal intrauterine pregnancies, spontaneous abortions, and ectopic pregnancies (EPs) conceived spontaneously or after clomiphene citrate (CC). RESULTS: Linear correlations between P and 1/DTs of hCG were poor. In contrast, nonlinear modeling with a hyperbolic curve fit the data well and allowed all of the data to be included for analysis regardless of the pregnancy type. Furthermore, this model could be used to explain the differential P concentrations seen in normal and abnormal first trimester pregnancies. The nonlinear hyperbolic model demonstrated that follicular events determine the maximal P production during early gestation. Human chorionic gonadotropin 1/DTs approximately equal to 0.5 sustain maximal P production. Progesterone production is then sustained by the rate of change of hCG. CONCLUSION: Nonlinear correlation analysis suggests that P production in early gestations is regulated by prior follicular events and the rate of hCG production.

Abortion, Spontaneous↗

PubMed1994

Relative operating characteristic analysis in reproductive medicine: comparison of progesterone and human chorionic gonadotropin doubling time as predictors of early gestational normalcy.

OBJECTIVE: To directly compare the ability of serum P and hCG doubling time to predict early gestational complications. DESIGN: We analyzed differences in P concentrations and hCG doubling times between spontaneously conceived normal and abnormal pregnancies (abortions and tubal pregnancies) during the first 49 days of pregnancy. Multiple 2 x 2 contingency tables were constructed that compared pregnancy outcome within discriminatory serum P concentrations or hCG doubling time. From these tables relative operating characteristic curves were generated for P concentration and hCG doubling times. The area under the curves were estimated and compared by the critical z score. RESULTS: Calculation of the areas under the curve for hCG doubling time and P concentration yielded values of 0.799 +/- 0.056 and 0.780 +/- 0.051 (mean +/- SEM), respectively. Critical z testing did not reveal a significant difference between the two curves. CONCLUSION: Serum P and hCG doubling times equally predict early gestational normalcy. Thus, a single serum P may be just as valuable in estimating risks of early pregnancy complications as repeated hCG measurements.

Chorionic Gonadotropin↗

PubMed1994

Expression of Clara cell 10-kD gene in the human endometrium and its relationship to ovarian menstrual cycle.

Clara cell 10-kD (cc10-kD) protein has been suggested to be the human counterpart of rabbit uteroglobin (UG). Like UG, this protein is also a potent inhibitor of phospholipase A2 (PLA2) and a substrate of transglutaminase. Although it has been established that UG gene expression in the rabbit endometrium is stimulated by progesterone, the expression of cc10-kD gene in the human endometrium is not clearly understood. The present study was undertaken to determine whether the cc10-kD gene is expressed in the human endometrium and whether its level of expression changes in relation to the ovarian menstrual cycle. Using reverse transcriptase polymerase chain reaction (RT-PCR) and immunofluorescence, we demonstrate that the cc10-kD gene is expressed in different stages of the menstrual cycle and that the highest level of expression is reached during the luteal phase. These results suggest that like rabbit UG, cc10-kD gene expression in the human endometrium may be stimulated by progesterone. Since cc10-kD is a potent inhibitor of PLA2 activity, this protein may play an important physiological role in regulating eicosanoid levels in the human uterus.

Animals↗

PubMed1994

Immunosuppression by hydatidiform mole trophoblast is neutralized by monoclonal antibodies to beta-interferon.

PROBLEM: In sheep and cattle, trophoblast-derived interferons serve as signals for the maternal recognition of pregnancy and may regulate the immunologic relationship between the fetus and mother. METHOD: In this study, soluble extracts prepared from human hydatidiform mole decidua (DE) and trophoblast (HME) were screened for immunosuppressive activity using an interleukin (IL)-2-dependent T-cell line (CTLL2). Antibody neutralization studies were performed with monoclonal antibodies to alpha- and beta-interferon (IFN). RESULTS: HME suppressed (P < 0.05) IL-2-stimulated (2 IU/well) CTLL2 proliferation at doses ranging from 500 (52 +/- 2% of control) to 100 (74 +/- 5%) micrograms/ml concentrations. DE also suppressed (P < or = 0.05) CTLL2 proliferation in a dose-related fashion from 500 (20 +/- 6% of control) to 100 (71 +/- 8%) micrograms/ml doses. Preincubation with the alpha- and beta-IFN antibody preparations had no effect on CTLL2 suppression by the DE sample. In contrast, the beta-IFN antibody partially neutralized the suppressive activity of HME at each of the dilutions tested. The monoclonal antibody to alpha-IFN failed to neutralize HME suppression at any of the doses tested. CONCLUSIONS: These results suggest that hydatidiform mole trophoblast produces a beta-IFN-like macromolecule that may abrogate maternal rejection responses that are harmful to the developing fetal allograft.

Antibodies, Monoclonal↗

PubMed1994

Gestational age correlates with immunosuppressive properties of hydatidiform mole pregnancies.

PROBLEM: Soluble trophoblast extracts (HME) from some human hydatidiform mole pregnancies suppress IL-2-dependent T-cell proliferation, while others express no immunosuppressive bioactivity. This study was designed to determine if suppression by HME was correlated with gestational age, uterine size, or hCG secretion. METHOD: Soluble extracts were prepared from nine hydatidiform mole trophoblast samples and screened for immunosuppressive activity using a murine cytotoxic T-cell proliferation assay (CTLL-2). Gestational ages were determined from last menstrual cycle and uterine size was estimated at the time of surgery. Serum samples were collected prior to uterine evacuation and were assayed for human chorionic gonadotropin (hCG). RESULTS: Four of nine HME samples significantly (P < 0.05) suppressed CTLL2 proliferation, while five exhibited no suppressive activity. A strong positive correlation (r = 0.639) was noted for the relationship between gestational age of the molar pregnancies and interleukin-2 (IL-2)-stimulated CTLL2 proliferation (expressed as % of control) in the presence of HME (500 micrograms/mL). This indicates that HME suppression of CTLL2 proliferation is highest in early gestation and then declines with increasing gestational age. A similar correlation was observed between estimated uterine size at surgery and CTLL2 proliferation with added HME, although the association was not as strong (r = 0.359). No association was noted between hCG levels and CTLL2 proliferative responses (r = -0.091). CONCLUSIONS: The results of this study suggest that production of immunosuppressive factors by hydatidiform mole trophoblast is developmentally regulated, and decreases with advancing gestation.

Cells, Cultured↗

PubMed1994

Laparoscopic Pomeroy tubal ligation as a teaching model for residents.

We reviewed our preliminary experience with laparoscopically directed bilateral midtubal resection for tubal ligation (endoscopic Pomeroy) as a potential teaching tool for the acquisition of endoscopic skills during residency training. Thirty-five laparoscopic Pomeroy and 206 banding procedures were reviewed. Age, parity and weight were similar in the two groups. The operative time for banding was reduced slightly after experience with > 10 procedures. In contrast, the operative time for laparoscopic Pomeroy procedures decreased dramatically after individual experience with only a few (< or = 5) procedures. The mean operative time for the Pomeroy group approached that of the more traditional banding technique at five procedures. Our data indicate that laparoscopic Pomeroy sterilization can be an effective teaching tool for operative laparoscopy, allowing residents to repeatedly perform an easy and safe procedure that incorporates basic techniques. Advanced operative endoscopic procedures could then be taught more efficiently after the acquisition of basic skills.

Adult↗