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Biomedical subjects

C W Tyler

Publications and source records attributed to C W Tyler.

At least 127 records · Page 7Linked to original sources
PubMed1980

Seasonal variation in spontaneous abortions.

Using a national sample of hospital discharges, we found identical seasonal patterns for spontaneous abortions and conceptions but no significant seasonal variation in the rate of spontaneous abortions per 1,000 conceptions. The differences between our findings and those of previous investigators of spontaneous abortion may reflect our more comprehensive definition of spontaneous abortion, our more complete estimate of the monthly number of conceptions, and our more rigorous statistical analysis. The periodic regression analysis (PRA) reported in our study may be useful in other studies that monitor short-term trends.

Abortion, Spontaneous↗
PubMed1980

Use of automated record linkage to measure patient fertility after family planning service.

Record linkage was used to identify births in 1974 to patients who had received contraceptive services from public family planning clinics in metropolitan Atlanta. The record linkage methodology is described. Results indicated that patient educational level, age, contraceptive choice, and race were the factors most associated with subsequent patient fertility. Black teenage patients experienced the highest fertility. Patients age 20 years and over with some education beyond high school experienced approximately one-third the fertility of less-educated patients. The program effectiveness of the IUD and the Pill was substantially better than that of foam and condoms. Excluding teenagers, the program effectiveness of the IUD was better than the Pill. Changes in family planning services for high-risk patients may help them achieve their fertility control objectives. Linking family planning clinic records to official birth records as described in this study can help determine clinic success in meeting patient objectives. Other applications of record linkage are discussed briefly.

Adolescent↗
PubMed1980

The underregistration of neonatal deaths: Georgia 1974--77.

We reviewed the neonatal outcome of 3,369 infants who weighed less than or equal to 1500 grams and who were born in Georgia during the years 1974--76. We matched 1,465 of these infants with a death certificate registered in the State's Vital Records. Upon review of the hospital records of the remaining infants, we identified 453 infants that died during the neonatal period without a death certificate being registered. Subsequently, we compared the hospital death registries for 1977 in Georgia and death certificates registered in Vital Records during 1977. We identified an additional 236 infants who died without a death certificate being registered. Forty per cent of these infants weighed greater than 1500 grams. Two major procedural errors regarding the filing of death certificates in Georgia at the local level contributed to this 21 per cent underregistratioon of neonatal deaths in 1974--77. The underregistration occurred disproportionately for rural areas, for unmarried mothers, and for Black infants. The reason for underregistration included failure of hospitals and morticians to file death certificates with the county registrars.

Adult↗
PubMed1980

A cluster of septic complications associated with illegal induced abortions.

Between August 7 and October 14, 1977, Clostridium perfringens organisms were isolated from endometrial and/or blood specimens from 3 women who had been hospitalized in McAllen, Texas, after having had illegal induced abortions. One of the women died of clostridial septicemia. A single abortionist was suspected in these 3 cases. The authors investigated the illnesses of these 3 women and those of 6 other women who were hospitalized at some time from January through October 1977 after having had illegal abortions but did not identify a common abortionist. The patient who died was a Medicaid-eligible woman who had had an abortion performed by a nonphysician after public funding of abortion was restricted in Texas as of August 5, 1977. The authors examined the medical records of all 230 women hospitalized in McAllen General Hospital with abortion complications from 1977 through January 1978. The local effect of restriction of public funds for abortion was to be studied. The incidence of women admitted to the hospital with febrile abortion complications after August 5, 1977, did not differ from that of women admitted from January 1 through August 4, 1977. However, the incidence of hospitalization of Medicaid-eligible women with abortion-related complications was greater after August 5 than it was in the earlier period.

Abortion, Illegal↗
PubMed1979

Local versus general anesthesia: which is safer for performing suction curettage abortions?

The relative safety of suction curettage abortions performed with either local or general anesthesia has not been clearly established. To compare the safety of these two anesthetic techniques, we studied 36,430 women who received local anesthetics and 17,725 who received general anesthetics for this operation in the United States from 1971 through 1975. The aggregated major complication rates for the two groups were similar, but there were significant differences between local and general anesthesia for specific complications and treatments. Local anesthesia was associated with higher rates of febrile and convulsive morbidity; however, general anesthesia was associated with higher rates of hemorrhage, cervical injury, and uterine perforation. Both anesthetic techniques appear to be safe, with similar degrees of overall safety, although each is associated with a different spectrum of complications.

Abdomen↗
PubMed1979

Epidemiology of hepatocellular adenoma. The role of oral contraceptive use.

A case-control study of hepatocellular adenoma (HCA), a serious though nonmalignant liver tumor, was conducted by the Center for Disease Control and the Armed Forces Institute of Pathology (AFIP). Interviews with 79 women with HCA and with 220 age- and neighborhood-matched controls were completed. Limited information was obtained on nine additional patients who had died. Women with HCA and hemorrhage have a greater risk of morbidity and death than those with other symptoms. Increasing duration of OC use increases the risk of HCA. Use of OCs with high hormonal potency and age over 30 years may further increase a woman's risk of HCA. Long-term users of OCs have an estimated annual incidence of HCA of 3 to 4 per 100,000.

Adolescent↗
PubMed1979

The health impact of restricting public funds for abortion. October 10, 1977--June 10, 1978.

The Center for Disease Control (CDC), Atlanta, Georgia implemented an eight-month prospective surveillance system in 24 hospitals distributed among states with and without public funding for abortion. Out of 3,157 visits for abortion-related complications, only 10 women gave a history of non-physician or self-induced abortion and none were Medicaid recipients. The small number of hospitals located in non-funded states and the smaller numbers of women served in these hospitals than in the funded states limited the power of out study. Women living along the Texas-Mexico border appeared more likely to have complications after illegal abortions than women from other areas of the country.

Abortion, Illegal↗
PubMed1979

Rapid assessment of visual function: an electronic sweep technique for the pattern visual evoked potential.

We have developed an electronic spatial frequency sweep technique for electrophysiological assessment of visual acuity and pattern vision. The technique allows an accurate and reliable measurement of VEPs to a full range of spatial frequencies in just 10 sec. Because the measurements are so rapid, the technique suggests several new improvements in the assessment of visual function. Sweeping spatial frequency linearly and extrapolating the high-frequency region of the VEP spatial-tuning function to zero voltage allows an estimate of acuity which correlates highly with psychophysical estimates of acuity. Variants of the procedure are appropriate for the assessment of refracture error, determination of equality of visual function for the two eyes and of binocular interactions, and for sequential assessment of therapeutic conditions.

Amblyopia↗
PubMed1978

Multiple spatial-frequency tuning of electrical responses from human visual cortex.

Human occipital potentials evoked by stimulation with a counterphase flickering grating were recorded by a digital narrowband filter technique. The data showed a surprising degree of narrow tuning to particular spatial frequencies in addition to the expected narrow temporal frequency tuning. At each temporal frequency, there could be two or more peaks of different spatial frequencies, each distinct from the whole field flicker response. Variations in this multiple spatial frequency tuning were investigated as a function of luminance, electrode location, and temporal frequency for several observers. The results are interpreted in terms of many stimulus-specific resonant neural circuits within the brain, and suggest that it is possible to make a highly detailed exploration of the responses of neural circuits to visual stimulation.

Electroencephalography↗
PubMed1978

Legalized abortion: effect on national trends of maternal and abortion-related mortality (1940 through 1976).

Both non-abortion-related maternal and abortion-related mortality declined prior to the Supreme Court decisions of 1973. In order to determine the effect of legalized abortion on maternal mortality, we have analyzed the secular trends in national abortion mortality ratios for 1940 through 1976, compared the trends to those maternal mortality ratios, and hypothesized reasons for differences between these trends. Between 1940 and 1950 and after 1965, deaths from abortion declined more rapidly than deaths from other causes associated with childbirth. However, between 1951 and 1965, maternal mortality related to pregnancy of childbirth declined more rapidly than abortion-related mortality. Five possible explanations exist for the more rapid decline in abortion deaths since 1965--selected underreporting, changes in coding practices, improved safety of illegal abortion, introduction of more effective contraception, and increased availability of legal abortion. We consider the last two explanations as the most likely reasons for the accelerated decline in abortion-related deaths.

Abortion, Legal↗
PubMed1978

An additional dimension to grating perception.

Visual acuity (A) for a two-dimensional multiplicative sinusoidal contrast grid (sinusoidal chessboard) was measured as a function of spatial frequency (omega) of modulation in one of the dimensions. The reduction in acuity as frequency was increased was well described by the equation: A = -2pikomega + c, where k and c are constants. At suprathreshold contrasts, the frequency of modulation appeared to be doubled relative to the underlying modulation frequency. This doubling is not related to the frequency of the harmonic components of the chessboard, but suggests the existence of a perceptual mechanism sensitive to areas of sinusoidal modulation which are seen at twice the frequency of the variation in contrast.

Depth Perception↗