The second stage of labor: factors influencing duration.

Prolonged second stage of labor is associated with increased perinatal mortality. Factors influencing second-stage duration are poorly understood. This study was undertaken to characterize those factors. A population of 473 nulliparous women and 491 multiparous women with spontaneous vaginal deliveries were analyzed extensively with history, physical examination (including clinical pelvimetry), labor and delivery data, and neonatal measurements. On the basis of stepwise multiple linear regression, epidural analgesia (p less than 0.0001), active-phase duration (p less than 0.0001), parity (p less than 0.0001), height (p less than 0.0004), birth weight (p less than 0.0003), and station at complete dilatation (p less than 0.027) predicted second-stage duration. The sum of their effect, however, accounted for less than 25% of the variability in second-stage length (total R2 = 0.233), leaving 75% of the variance unexplained.

Development of the U.S. Army Ambulatory Care Data Base.

In providing more than 22 million outpatient visits per year, the U.S. Army Medical Department is one of the largest Health Maintenance Organizations in the world. Accordingly, the need for an Ambulatory Care Data Base (ACDB) to provide management, epidemiological, and cost indicators has long been recognized by the Army. As part of a multi-year study, the ACDB was developed to meet this need. Issues and problems faced in implementing such a wide-scale effort are discussed. Preliminary results from data collected on over 3 million outpatient visits include types of health care providers and clinic specialties, with the corresponding number of visits.

Finite sample properties of maximum likelihood estimates of the recombination fraction in double backcross matings in man.

The properties of the maximum likelihood estimator (MLE) of the recombination fraction, theta, based on various numbers and sizes of sibships derived from double backcross matings are exactly explored where the coupling phases are presumed equally likely (which for two-generation data is generally the case). The results indicate that for large values of theta the expectations are severely biased. The bias, variance, and measures of normality of the MLE behave erratically for small sizes and numbers of sibships. The implications for chromosome mapping are discussed.

The estimation of blood platelet survival. VI. Evaluation of the graphical method.

An experiment was performed in which 13 scientists experienced in analyzing data on platelet survival were sent blind duplicate sets of ten platelet survival curves and requested to fit the "best" straight line through the data by eye and determine its point of intersection with the time axis. The duplicate sets labeled "control" and "aspirin" respectively were artificial data generated from evaluation for various times of a gamma curve of order five and adding random independent normal (Gaussian) errors having a standard deviation of 0.03. The results were analyzed to examine inter- and intra-observer variance, reproducibility and bias. The range of means of estimated survival was 8.68 days to 11.59 days and in the control data showed about 63 times as much variance among observers as that due to random error of measurement alone. The "aspirin" data showed similar results. Correlation coefficients within observers for the pairs of estimates varied from -0.307 to +0.920. Three observers showed strong systematic differences between the duplicate readings. These results provide clear evidence of the need for formal, rather than graphical, analysis of the data.

Effect of estrogen on sensitivity of rabbit bladder and urethra to phenylephrine.

The sensitivity of alpha-adrenoceptors to phenylephrine as indicated by the ED50 of the rabbit bladder and urethra was compared for segments in vitro from control (estrous), ovariectomized, ovariectomized-estrogen-treated, and pregnant animals. In control animals there was a trend for urethral segments to be more sensitive to phenylephrine (lower ED50) than bladder segments. This difference was abolished by castration, which decreased the sensitivity of the anular urethral segment, and by pregnancy, which tended to enhance the sensitivity of the bladder. The tension generated by bladder segments was enhanced by pregnancy and tended to be decreased by castration. The effects of castration tended to be reversed by treatment with estrogen (1 microgram per kg of body weight per day for 14 days). These data indicate that estrogen can influence the response of the urethra and urinary bladder to alpha adrenergic stimulation.

Break points in human chromosomes.

Break points of structural rearrangements of human chromosomes can be identified by banding techniques. The present study attempts to analyze the randomness and the distribution of the reported spontaneous break points in the human genome. Reports of break points in structural rearrangements of human chromosomes from the published sources up to October 1976 were analyzed. Based on the assumption that each unit length of band has an equal chance of being broken, chi2 tests show that positions of breakage are highly non-random; that is, breaks are more frequent in the negative band areas and in the centromeric and terminal regions. In double-break rearrangements the same band types tend to rejoin. The distribution of breaks is not proportional to the chromosome length. The longer chromosomes (i.e., 1--12, X) have a lower number of breaks per unit length, while the shorter chromosomes (i.e., 13--22, Y) have a greater number of breaks per unit length with the exception of chromosomes 4, 9, 10, 16, 17, 19, 20 and X. Out of the whole genome, chromosomes 9, 13, 18, 21, 22 and Y have the most breaks per unit length and chromosomes 16, 6, 2, 3 and 19 have the fewest. 18p11, 21q22 and Yp11 are the three bands with most frequent breaks. There are 53 bands where no breaks have been reported.

The familial component in longevity--a study of offspring of nonagenarians: III. Intrafamilial studies.

The effect of parental longevity on the length of survival of offspring has been examined according to selected demographic and environmental characteristics. The present study is based on 7,103 progeny, 20 years old or older. They were the sons and daughters of 1,766 men or women, 90 or more years old, who were alive in 1922-1930 at the time of ascertainment. The age at death of the other parent of the offspring is the basis of classification used in this analysis. A positive relationship was found between age at death of the non-proband parent and the age at death of the offspring. This relationship existed regardless of similarities or differences in the characteristics analyzed.

Prevalence, goals and complications of heterosexual anal intercourse in a gynecologic population.

In a prevalence study of 526 consecutive gynecologic patients, a history of heterosexual anal intercourse (AI) was elicited in 25% and was a regular means of sexual gratification in 8% and was thus deemed active, pleasurable, and intercourse (APAI). The prevalence of AI and APAI was similar in patients of Mexican-American, Black-American and Anglo-American background and in patients older or younger than 30 years. The APAI participants were evenly distributed between cancer detection, family planning, free clinic and private consultant populations. The goals of the APAI group associated with heterosexual anal intercourse were pleasure, orgasm and contraception. The reported complications were infrequent and were related to infectious diseases, local irritation and trauma. Although the average duration of APAI was two years, no unusual pelvic or rectal characteristics were noted in these patients.

Evaluation of indium-111 as a new high photon yield gamma-emitting "physiological" platelet label.

In order to evaluate indium-111 (111In) as a "physiological" platelet label, rabbit platelets were labeled in vitro with 111In-8-hydroxyquinoline. The in vivo behavior of 111In labeled platelets was then compared with that of chromium-51 51Cr) labeled platelets in the rabbit. Several important features were evident. First, unlike 51Cr, reasonable platelet labeling efficiency could be achieved with 111In, even when the platelets were suspended in small amounts of autologous plasma. Second, the initial recovery of platelets at 20 minutes after infusion was significantly higher for the 111In labeled platelets than for 51Cr labeled platelets, providing the platelets were suspended and "washed" in plasma. Third, the mean survival time of 111In labeled platelets, as estimated using four different mathematical models, was comparable with that of 51Cr platelets. Finally, the high photon yield of gamma emitting 111In, unlike 51Cr, permits quantitative gamma camera imaging of the in vivo distribution of labeled platelets. Thus, this nuclide possesses advantages as a platelet label that will foster statistically more accurate kinetic research as well as quantitative in vivo distribution studies in humans.

A matrix method for calculating recurrence risks of unilocal disorders for genetic counselling.

A matrix method to calculate conditional likelihoods in a pedigree and use them to determine recurrence risks for unilocal disorders in genetic risks is presented in this paper. Different matrices are assigned to individual members of the pedigree and combined into matrix expressions. The method is explained for X-linked recessive conditions and autosomal dominant conditions with incomplete penetrance.