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Biomedical subjects

C W Tyler

Publications and source records attributed to C W Tyler.

At least 145 records · Page 8Linked to original sources
PubMed1978

Comparative risk of death from legally induced abortion in hospitals and nonhospital facilities.

The rapid emergence of nonhospital abortion facilities as alternatives to traditional hospital-based surgical care has raised important questions concerning their safety. Using 1974--1975 data from the Center for Disease Control's nationwide surveillance of abortion mortality and the Alan Guttmacher Institute's nationwide surveys of abortion providers, we have calculated the risk of death from legally induced abortion in the United States at less than or equal to 12 menstrual weeks' gestation in hospitals and nonhospital facilities (clinics and physicians' ofices). The adjusted death-to-case rate for hospitals was 1.1 deaths/100,000 abortions, compared with a crude rate of 1.0 for nonhospital facilities. The risk of death from legal abortion in nonhospital facilities is apparently similar to the risk in hospitals.

Abortion, Legal↗
PubMed1978

World Health Organization studies of prostaglandins versus saline as abortifacients. A reappraisal.

The World Health Organization (WHO) Task Force on the Use of Prostaglandins for the Regulation of Fertility has sponsored a series of randomized clinical trials and case-series investigations to assess the effectiveness and safety of prostaglandins as abortifacients. Our reanalysis of the WHO studies found the prostaglandins to be faster and more hazardour than hypertonic saline as intraamniotic abortifacients. Moreover, studies by the Center for Disease Control imply that dilatation and evacuation (D&E) may be more effective, safe, convenient, and inexpensive than prostaglandins for abortions after 12 weeks' gestation, especially in the 13- to 16-week interval. For gestations of greater than or equal to 17 weeks, the occurrence of live births in prostaglandin-induced abortions has produced serious legal and ethical problems in the United States. Until the effectiveness and safety of other prostaglandins regimen approach that of D&E, we feel that D&E should be the index of comparison against which newer methods of inducing abortion are tested.

Abortion, Induced↗
PubMed1977

Mid-trimester abortion by dilatation and evacuation: a safe and practical alternative.

Abortions by dilatation and evacuation after the 12th menstrual week of pregnancy are said to be both hazardous and impractical. To evaluate this hypothesis, we compared the safety and feasibility of 6213 abortions by this means and 8662 induced by intra-amniotic instillation of saline during the 13th to the 20th week of pregnancy. Abortions by dilatation and evacuation had a lower rate for major complica-tions (0.69 vs. 1.78 per cent; P is less than 0.001) and lower rates for treatment of complications, including antibiotic administration (2.22 vs. 5.65 per cent; P is less than 0.001), blood transfusion (0.19 vs. 0.91 per cent; P is less than 0.001), and curettage or manual evacuation of the uterus (0.98 vs. 34.10 per cent; P is less than 0.001). Such abortions also had a lower rate for failure of the method to produced abortion (0.11 vs. 2.52 per cent; P is less than 0.001). Although large, randomized trials are required to determine the appropriate role of mid-trimester abortion by this means, this method appears safe and practical through the 20th week of pregnancy.

Abortion, Induced↗
PubMed1977

Movement adaptation in the visual evoked response.

Visual evoked responses to sinusoidal movement before and after adaptation to linear movement were compared. Fourier analysis indicated that the responses evoked by sinusoidal movement were insensitive to direction of movement. Following adaptation, the harmonics describing the waveforms changed in magnitude and phase, and showed an asymmetry of waveshape not evident before adaptation. The data are consistent with the existence of movement-sensitive cells within the intact visual system which change in response characteristics as a result of adaptation to linear movement.

Adaptation, Ocular↗
PubMed1977

Abortion deaths associated with the use of prostaglandin F2alpha.

Six abortion-related deaths associated with the use of prostaglandin F2alpha were reported through the Center for Disease Control's surveillance of abortion deaths between 1972 and 1975. Prostaglandin may have had only indirect association with these deaths. The patients' ages ranged from 16 to 38 years, their length of gestation ranged from 15 to 24 menstrual weeks, four were white, and three were nulliparous. Four patients had pre-existing conditions that increased their risks and contributed to their death. The estimated death-to-case rate for prostaglandin F2alpha was 10.5 per 100,000 abortions. Although lower than the rate for intra-amniotic saline instillation, this death-to-case rate is only an approximation. The relative safety of intra-amniotic prostaglandin F2alpha as a second-trimester abortifacient, compared to saline, remains to be established.

Abortifacient Agents↗
PubMed1977

Legal abortion mortality in the United States. Epidemiologic surveillance, 1972-1974.

As determined by the Center for Disease Control's epidemiologic surveillance of abortion mortality, the death-to-case rate for legal abortion in the United States for the three years 1972 to 1974 was 3.9/100,000 procedures. This mortality compares favorably with that from other commonly performed surgical procedures. Women who were older, were of nonwhite races, had the procedure in their state of residence, were at later gestational age, and who underwent intrauterine instillation or major abdominal surgery had the highest mortality. Duration of pregnancy proved to be the most important determinant of risk. Compared to mortality from pregnancy and childbirth, legal abortion in the first trimester was almost nine times safer.

Abortion, Legal↗
PubMed1977

The association between oral contraception and hepatocellular adenoma--a preliminary report.

Women with long-term use of oral contraception (OC) are at increased risk of developing a serious, though nonmalignant, liver tumor--hepatocellular ademona (HCA)--according to a case-control study conducted by the Center for Disease Control (CDC) in collaboration with the Armed Forces Institute of Pathology (AFIP). The tumor is sometimes fatal, deaths usually being due to sudden rupture and hemorrhage. This study suggests that, in addition to long-term OC use, a women's age and the hormonal potency of the OC she uses affect her changes of developing HCA. Women 27 years old and older who have used OC with high hormonal potency for 7 or more years are at the greatest risk.

Carcinoma, Hepatocellular↗
PubMed1977

The risk of dying from legal abortion in the United States, 1972-1975.

Data gathered by the Center for Disease Control (CDC) through epidemiologic surveillance of deaths associated with legal abortions performed from 1972 through 1975 are analyzed by the type of procedure and the gestational age of the patients. Analysis shows that deaths increase at higher gestational ages and that the risk of death from abortion is highest with hysterotomy and hysterectomy and lowest with suction curettage. Second trimester instillation procedures are associated with higher rates of mortality than first trimester curettage procedures, even when dilatation and evacuation at 13-15 weeks' gestation is included as a curettage procedure. A case history of a patient who died as a result of legal abortion demonstrates that while legal abortion is a safe surgical procedure, some of the deaths that still occur can be prevented.

Abortion, Legal↗
PubMed1977

Methods of midtrimester abortion: which is safest?

In the United States, the three principal methods of abortion for patients at 13 or more menstrual weeks' gestation are intraamniotic instillation of saline or prostaglandin F2alpha (PGF2alpha) and dilatation and evacuation (D&E). The relative safety of these methods, however, has not been established. This report compares the three methods using data on 17467 abortions collected by the Joint Program for the Study of Abortion under the auspices of the Center for Disease Control (JPSA/CDC). Abortion by D&E was found to be significantly safer than abortion by saline instillatin (p less than 0.001), and abortion by saline instillation was significantly safer than by PGF2alpha (p less than 0.01). Moreover, midtrimester D&E is both safe and practical; it is a direct and rapid procedure which can be performed on an outpatient basis. Although PGF2alpha accelerated the time required for abortion, it also significantly increased serious morbidity.

Abortifacient Agents↗
PubMed1977

Family planning and the primary care physician.

Family planning has become an important issue in modern life. The physician must be prepared to advise patients on the advantages and risks of both old and new methods and to determine which method is most acceptable and will therefore be most effective.

Abortion, Induced↗
PubMed1977

Stereomovement from interocular delay in dynamic visual noise: a random spatial disparity hypothesis.

This paper reports a series of tests of the assumptions entailed in the random spatial disparity hypothesis (Tyler, 1974) of the stereophenomenon that occurs on viewing dynamic visual noise with an interocular delay. The results support the hypothesis in opposition to 2 alternative hypotheses. A new stereophenomenon is reported in which reversed steromovement is perceived when viewing dynamic visual noise that has both an interocular delay and complementary contrast between the 2 eyes. Only the random spatial disparity hypothesis appears to account for this reverse stereophenomenon.

Depth Perception↗
PubMed1977

Midtrimester abortion by intraamniotic prostaglandin F2alpha. Safer than saline?

Published reports disagree on the risks of intraamniotic prostaglandin F2alpha (PGF2alpha) for midtrimester abortion. To evaluate the safety and efficacy of intraamniotic PGF2alpha, we compared 1241 PGF2alpha and 10,013 saline abortions performed during the 13th to the 24th menstrual week. The results were reported in the Joint Program for the Study of Abortion/CDC, a multicenter prospective study. PGF2alpha abortions required less time (P less than .001) but had higher rates of major complications (P less than .01), antibiotic and operative treatment of complications (P less than .001), and readmission to a hospital (P less than .001). These findings challenge the current contention that PGF2alpha is safer than saline as an abortifacient.

Abortifacient Agents↗
PubMed1977

Binocular interactions in the human visual evoked potential after short-term occlusion and anisometropia.

The human visual evoked potential was recorded during 9 hr. of monocular occlusion or deprivation of fine detail by anisometropia. Some decrement in the response from the occluded eye was evident, but the major result was a sustained increase in the response from the nonoccluded eye. The anisometropic condition produced no decrement for stimulation of the deprived eye, but again there was an increase in the response from the nondeprived eye. Under some conditions the changes became apparent after only 6 hr. of deprivation. The data may be interpreted in terms of binocular competition or reciprocal inhibition at the level of the visual cortex or lateral geniculate nucleus.

Evoked Potentials↗