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Biomedical subjects

R O Davis

Publications and source records attributed to R O Davis.

At least 91 records · Page 5Linked to original sources
PubMed1984

Delay in delivery: influence of gestational age and the duration of delay on perinatal outcome.

The potential benefits to be gained in neonatal survival and freedom from serious morbidity by delaying delivery at various gestational ages was explored by examining the results of studies of neonatal mortality and subsequent morbidity published from 1978 and 1984. The major benefits were found to occur between 24 and 27 weeks' gestational age. In general, little benefit was found in delaying delivery after 34 weeks' gestational age.

Birth Weight↗
PubMed1984

Effect of labor on the postpartum bladder.

Urodynamic investigations were performed on 20 patients at 48 hours and at four weeks after delivery to assess the effect of modern obstetric practice on the postpartum bladder. Although there were significant differences in some values over this period, the mean urodynamic measurements on both occasions were within normal limits. It is concluded that the current management of labor does not predispose women to bladder hypotonia, the chief factors responsible being avoidance of prolonged labor and early catheterization after delivery.

Adult↗
PubMed1979

Association of extrauterine fetal death with failure of prostaglandin E2 suppositories.

The use of prostaglandin E2 vaginal suppositories is an effective method of uterine evacuation for patients with intrauterine fetal demise. Advanced extrauterine gestation, because of its rarity, is usually not a primary consideration for patients presenting with fetal death. This report presents 4 such cases and strongly suggests that, when this drug is used for the treatment of fetal death, failure to induce contractions and to effect uterine evacuation within a reasonable time should prompt the consideration of extrauterine pregnancy.

Abortion, Induced↗
PubMed1978

Diagnostic compound B-mode ultrasound scanning in gynecology.

Diagnostic compound B-mode ultrasound scans done on gynecologic patients during the past three years were reviewed and compared with surgical findings or clinical follow-up. The 190 scans were analyzed and categorized as diagnostic, compatible (or confirmatory), equivocal, misleading, or negative. Although only 6.4% were diagnostic, the majority (66.3%) were compatible with the clinical and pathologic findings. Criteria for interpreting B-mode scans are discussed.

Diagnostic Errors↗
PubMedDate not supplied

Automatic analysis of human sperm motion.

A new computerized methodology is described in which sperm movement characteristics are analyzed automatically. Video fields containing images of spermatozoa are electronically digitized, and the centroid position of each sperm head is determined. Over time, strings of centroids identify the swimming paths of individual spermatozoa. Details of path acquisition are described for human spermatozoa in semen, and include a discussion of how individual cells are identified and distinguished from each other. A diversified set of movement characteristics is computed for each spermatozoon, including two new measures of path shape based on the instantaneous turning angle. The traditional and the new measures of vigor and swimming pattern are evaluated and compared for consistency and redundancy. Analysis of data from human semen indicates that the new angular measures may be particularly useful in discriminating between spermatozoa exhibiting widely different patterns of motion.

Humans↗
PubMedDate not supplied

Automated analysis of toxicant-induced changes in rat sperm head morphometry.

An automated sperm morphometry analysis (ASMA) instrument was developed to obtain measurements of toxicant-induced changes in rat sperm head morphometry. 1,3-dinitrobenzene (1,3-DNB), a testicular toxicant known to affect sperm parameters, was used. Twelve-week-old Sprague-Dawley rats were allocated to a control (C) and to two 1,3-DNB treatment groups (T1 = 15 mg/kg; T2 = 25 mg/kg). 1,3-DNB was administered as a single dose by gavage, and animals were sacrificed 22 days after exposure. Sperm were collected, and morphology smears were made by a standard method. One hundred sperm heads were digitized on each slide, and 8 metric measurements were automatically reported. All measurements tended to decrease in a dose-dependent manner with increasing doses of 1,3-DNB. All values for total width (Wa) and interior width (W(e)) were significantly different from one another. Wa/L was significantly larger in the control than in T1 or T2, and symmetry (S = Wb/Wa) was significantly smaller in the control than in T1 or T2. Multivariate cluster analysis revealed three subpopulations that were also visually distinct. Subpopulation no. 1 was normal, based on published descriptions of normal rat sperm; subpopulation no. 2 was abnormal with a flattened curvature and a normal length; subpopulation no. 3 was abnormal with a foreshortened length and a flattened curvature. T1 and T2 contained significantly more sperm from subpopulation no. 2 and no. 3 than C (T1 = 22% and T2 = 34% vs. C = 8% by cluster analysis). C had 93% normal sperm, while the treatments had 78% and 66%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

Effects of maternal infections on fetal adrenal steroid production.

We sought to determine the effect of maternal infections on the fetal hypothalamic-pituitary-adrenal axis. Umbilical cord blood was collected at vaginal delivery after labor (24-44 wk. gestation) from 361 infants of women having normal pregnancy ( apart from preterm delivery in some) and 110 infants of women diagnosed with infections: 86% of these women had amnionitis. Infants exposed to antenatal corticosteroids, being growth retarded, or having developmental abnormalities that would be expected to alter function of the hypothalamic-pituitary unit were excluded. Umbilical cord serum was assayed for dehydroepiandrosterone sulfate (DS) and for cortisol. The data were analyzed by use of SAS. The gestational age of the infants of normal women (35.8+/-0.2 wk., Mean +/- SE) was greater than that of the infants of women having infections (34.3+/-0.4 wk., P = 0.003). Umbilical cord serum levels of DS and cortisol rose as a function of gestational age in both groups of infants (P<0.01). Despite being, on average, 1 wk. younger than the normal infants are, the infants of women having infections during pregnancy had higher serum levels of cortisol and DS than did those infants of the normal women. These data are consistent with activation of the fetal hypothalamic-pituitary-adrenal axis in pregnancies complicated by maternal infections. Such a fetal response could be the consequence of transplacental passage of products of the activated maternal immune system.

Adrenal Cortex Hormones↗
PubMedDate not supplied

Standardization and comparability of CASA instruments.

Thirty human semen specimens were analyzed using a standard manual method, then videotaped and reanalyzed using two different computer-aided sperm analysis (CASA) instruments (the HTM system, Hamilton-Thorn Research, Danvers, MA, and the CTS system, Motion Analysis Corp., Santa Rosa, CA). Videotaped specimens were analyzed by CASA for 5 frames for sperm concentration (CON) and percent motility (MOT), and for 15 frames for kinematic variables (straight-line velocity, VSL; curvilinear velocity, VCL; linearity, LIN; and amplitude of lateral head displacement, ALH). Machine parameter settings for the two instruments were matched as closely as possible. CASA values were compared with each other for all measures and with manual results for sperm count and the percentage of motile sperm. Results show: 1) HTM and CTS average values for CON are not different from manual measures for the 5- or 15-frame analysis, but slight differences are seen between CTS and HTM; 2) average values for MOT for the 5-frame analysis are higher than the 15-frame analysis for both instruments, but the average manual measurement for percent motility is much higher than any CASA value; 3) average VSL and LIN are slightly higher for HTM than CTS, but pair-wise comparison shows a high degree of concordance between the instruments; and 4) the mean values for VCL and ALH are equal for the two instruments, and there is a close concordance for the pair-wise comparison for VCL; however, pair-wise comparison of ALH reveals significant differences between the instruments. Overall, the differences seen between these instruments are slight, and are probably not biologically or clinically significant.

Diagnosis, Computer-Assisted↗
PubMedDate not supplied

New measures of sperm motion. I. Adaptive smoothing and harmonic analysis.

Several kinematic measures from computer-aided sperm analysis (CASA) instruments depend critically upon the computation of the spatially averaged path of a sperm's curvilinear swimming trajectory. Presently available instruments compute the average path by smoothing the curvilinear trajectory using a fixed-length running average. We demonstrate that this method significantly distorts the spatially averaged path for irregularly swimming sperm, both within and between trajectories, resulting in inaccurate calculations for the velocity of the average path (VAP), amplitude of lateral head displacement (ALH), beat-cross frequency (BCF), wobble of the curvilinear trajectory (WOB), and straightness of the curvilinear trajectory (STR). The authors introduce an alternative approach, based on engineering signal processing techniques, where the width of the running average is adapted to the changing wavelengths of the major spatial oscillations of each curvilinear trajectory. How this adaptive method results in less distortion of the average path and produces more accurate characterizations of the above measures is shown. This method is implemented in a computer program developed by the authors, called PathTool. It is also demonstrated that the simple methods used to characterize the frequency and amplitude of the major oscillation in a sperm's curvilinear trajectory (ie, BCF and ALH) are only accurate for the most periodic, progressive, and symmetrical trajectories. Three new measures are introduced, based on mathematical harmonic analysis, that are more robust alternatives to the present methods. These new methods and measures are initially evaluated using prototypical sperm trajectories from human semen. Results suggest that adaptive smoothing and harmonic analysis produce more accurate estimates of the frequency and magnitude of oscillations in sperm trajectories than the method based on fixed-length smoothing, BCF, and ALH.

Animals↗
PubMedDate not supplied

Isolation of Mycoplasma hominis and Ureaplasma urealyticum from amniotic fluid at 16-20 weeks of gestation: potential effect on outcome of pregnancy.

Samples from 61 amniotic fluids (33 discolored and 28 clear) collected by amniocentesis between 16 and 20 weeks gestation were cultured for microorganisms. Two of the discolored fluids were positive for Mycoplasma hominis, and two were positive for Ureaplasma urealyticum. Neither organism was isolated from samples of clear amniotic fluids. No other bacteria, viruses, or chlamydiae were isolated from fluids of any patient. The results prove that both M. hominis and U. urealyticum can infect the amnionic sac early in gestation without rupture of the fetal membranes. U. urealyticum was shown to cause a clinically silent, chronic (up to two months) intrauterine infection characterized by an intense inflammatory response. Complications in three of the four patients from whom mycoplasmas were isolated suggest, but do not prove, that mycoplasmal infection of amniotic fluid may have an adverse effect on outcome of pregnancy. Further studies are necessary to substantiate this implication and to determine the relationship between infection and discoloration of amniotic fluid.

Adult↗