Biomedical subjects
Publications and source records attributed to R Walton.
This study describes the method and principles of fetal echocardiography, analyzing the technics and the utility of bidimensional mode, M mode and Doppler ultrasound on congenital fetal cardiopathies. The importance of early diagnosis in the structural alterations and fetal cardiac arrhythmias is emphasized.
Normal fetal hearth biometry is analyzed by echocardiography in 80 pregnant women with 20 and 40 gestational weeks. Intraventricular septum, aorta, left and right ventricular dimensions were obtained. All dimensions showing progression with gestational age.
We present 119 echocardiographies in 90 high-risk pregnancies, 20 to 40 weeks gestational age. There were found 18 fetuses with abnormal examinations (20%), six of them with structural alteration (6.6%), and 14 arrhythmias (15.5%). The diagnostic correlation in structural alterations with a sensibility of 83% and 100% specificity, and 100% of sensibility and specificity in arrhythmias. The importance of antenatal diagnosis in cardiac malformations and arrhythmias is described.
A prospective study on 25 adolescent pregnant women was carried out. A single measurement of the systolic-diastolic ratio (S/D) was taken using continuous Doppler on arcuate arteries on both sides of the uterus. All measurements were taken after the 16th week of amenorrhea. The relationship between Doppler velocimetry and birthweight was established. Seven newborns were small for gestational age. The sensitivity of this method was 94.4% and specificity was 57.1%. Positive predictive value was 80.0% while negative predictive value was 85.0%. The importance of measuring both arcuate arteries and determining the site of placental insertion for proper interpretation of results is stressed.
One year following root canal treatment and internal etching and bleaching of anterior teeth in dogs, the animals were sacrificed and the teeth prepared for stereomicroscopic or light microscopic examination. Evidence of cervical root resorption and ankylosis was noted on several teeth. The bleaching factors associated with the teeth exhibiting resorption were heat with 30% hydrogen peroxide. Resorption was not related to walking bleach or to internal etching alone.
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Its related the development of two application in Computer Aided Instruction (CAI) in Medical Education with an Apple IIc and 128 K. The first using the PILOT for student; and the second a program of "Simulation of Labor Troubles" for interns and specialty training developed in BASIC. Am special point is the lower time training for the teacher with the PILOT. Its demonstrate the improvement through the qualification in relation to other evaluation in the same year and the relations with other questions during the same test.
Healthy lying-in women admitted to the Clinical Hospital of the University of Chile, most of them belonging to the low socioeconomic of Santiago (Chile), showed a steady decrease in the plasma levels of total protein, albumin, beta-globulin, IgA, and IgM, and also a striking increase in the plasma level of alpha 1-Globulin. This trend was ascertained from december 1982 to august 1985, and the pattern of plasma protein change is similar to that found in human malnutrition. The observed changes in the immunoglobulins levels suggest a different behavior between IgM and IgA that do not cross the placenta and IgG that crosses it.
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To establish sensitive histologic criteria for small congenital nevi (SCN), we examined 29 biopsy specimens of SCN from patients younger than age 1 year by serial sectioning and S100 immunoperoxidase staining. The depth of papillary and reticular dermal infiltration was variable; only the results of six biopsy specimens contained nevomelanocytes in the lower third of reticular dermis. However, all cases had focal nevomelanocytic involvement of adnexa at the midreticular dermis or below (26 of 29 cases in eccrine and 15 of 29 in pilosebaceous structures). Follow-up specimens in ten patients were obtained (mean interval, 10.25 years), and no difference in histologic pattern or cytology was observed. There were variable size increases in the surface area of SCN, ranging from no increase to a maximal ninefold increase.
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The hypothesis that the Rh and ABO blood systems behave like the HLA system in relation to mother-conception tolerance-rejection mechanisms was tested in 25,501 mother-infant pairs. According to this hypothesis, heterozygotes carrying a paternal gene that is not present in their mothers should be better tolerated than homozygotes. Significantly more BO infants born to AO mothers. AO infants born to BO mothers, Rh(+) heterozygotes born to Rh(-) mothers, and less significantly AO infants born to OO mothers confirm the hypothesis. Fewer homozygotes occurred in Rh(-) infants born to Rh(+) mothers and in O infants born to non-O mothers. Deviations from the Hardy-Weinberg equilibrium found in the ABO system were modified by the Rh and sex of the infant. These data strongly support the hypothesis that at least two feto-maternal systems influence the destiny of pregnancies: the classical known incompatibility system which operates late in pregnancy and a new one which is based on the induction of maternal tolerance early in pregnancy: maternal tolerance seems to be better elicited by heterozygous eggs or embryos carrying a gene not present in the mother. The data also support the hypothesis that the sex ratio is influenced by feto-maternal tolerance-rejection mechanisms associated with the ABO and Rh systems.
Postoperative monitoring of vascular perfusion was performed in 72 revascularized/replanted digits in 40 patients. Sodium fluorescein (1.0 to 1.5 mg/kg) was administered intravenously every 2 hours for 36 to 48 hours beginning immediately after surgery. Quantitative fluorescence readings of each injured digit were obtained 10 minutes after fluorescein injection and were compared with readings from an uninjured (control) digit. A ratio between the fluorescence of the injured digit and that of the control digit was used for analysis. Viable digits had a fluorescein perfusion ratio of 86.4 +/- 16. Digits that did not survive had fluorescein perfusion ratios of 5.2 +/- 10 (p less than 0.001). The results of this study indicate that quantitative surface fluorescence assessment of revascularized/replanted digits is a minimally invasive, and reliable tool for monitoring vascular perfusion.