Ronald B. Harrist

Estimation of fetal weight with the use of head, body, and femur measurements—A prospective study

In utero estimates of fetal weight were evaluated prospectively in 109 fetuses with the use of sonographic models developed in a previous study. This report confirms that the best in utero weight estimates result from the use of models based on measurements of head size, abdominal size, and femur length. Since the accuracy of these models (1 SD = 7.5%) is significantly better than those based on measurements of head and body (e.g., biparietal diameter, abdominal circumference), we recommend routine use of such models in obstetric sonography.

Fetal biparietal diameter: a critical re-evaluation of the relation to menstrual age by means of real-time ultrasound.

The relationship between fetal biparietal diameter (BPD) and menstrual age was determined by cross‐sectional analysis of 533 fetuses (12 to 40 weeks) examined with a linear array real‐time (dynamic image) scanner using specifically defined methodology. Mathematical modeling of the data demonstrated that the optimal fit was the linear cubic function (r2 = 99 per cent); predicted BPD values calculated from the function were most comparable with composite data from cross‐sectional studies performed with static scanners after 1974 (average difference, 0.22 mm) and least comparable with composite data from cross‐sectional studies performed with static scanners before 1974 (average difference, 2.0 mm). The variability associated with predicting menstrual age from the BPD increased progressively throughout gestation; the maximal variability was noted between 36 and 42 weeks (+/‐ 3.6 weeks). Comparison with our longitudinal study of BPD growth indicates that the cross‐sectional data represent a valid estimate of the true longitudinal BPD growth curve of the population.

Safer choices: reducing teen pregnancy, HIV, and STDs.

Objectives. This study evaluated the long-term effectiveness of Safer Choices, a theory-based, multi-component educational program designed to reduce sexual risk behaviors and increase protective behaviors in preventing HIV, other STDs, and pregnancy among high school students. Methods. The study used a randomized controlled trial involving 20 high schools in California and Texas. A cohort of 3869 ninth-grade students was tracked for 31 months from fall semester 1993 (baseline) to spring semester 1996 (31-month follow-up). Data were collected using self-report surveys administered by trained data collectors. Response rate at 31-month follow-up was 79%. Results. Safer Choices had its greatest effect on measures involving condom use. The program reduced the frequency of intercourse without a condom during the three months prior to the survey, reduced the number of sexual partners with whom students had intercourse without a condom, and increased use of condoms and other protection against pregnancy at last intercourse. Safer Choices also improved 7 of 13 psychosocial variables, many related to condom use, but did not have a significant effect upon rates of sexual initiation. Conclusions. The Safer Choices program was effective in reducing important risk behaviors for HIV, other STDs, and pregnancy and in enhancing most psychosocial determinants of such behavior.

Gender and treatment differences in knowledge, health beliefs, and metabolic control in Mexican Americans with type 2 diabetes.

PURPOSE The purpose of this project was to describe metabolic control, knowledge, and health beliefs of Mexican Americans with type 2 diabetes. METHODS The study site was Starr County, Texas, a border community located on the Rio Grande River and bordering northern Mexico. Of the total sample of 360 persons, 252 agreed to participate in this intervention study and were randomized either to the treatment group or the control group that waited 1 year to begin the intervention. RESULTS The majority of individuals were Spanish-speaking females with a mean age of 54 years and a mean diabetes duration of 8 years. For those treated with diet only, males exhibited higher fasting blood glucose levels than females. Gender effects were seen for cholesterol level, with females exhibiting higher levels than males. Males expressed stronger perceptions of control and social support for diet. Bivariate relationships were found between acculturation and diabetes knowledge. The health belief subscales of control and impact on job together explained 16% of the variance in HbAlc values. CONCLUSIONS Males and females held differing beliefs about ability to control their diabetes and degree of social support for diet. The impact of gender differences on ability to integrate diabetes self-care and on effectiveness of diabetes programs has not been determined but should be considered in future research.

Longitudinal studies of fetal growth with the use of dynamic image ultrasonography

To characterize the growth of individual fetuses, serial measurements of the crown-rump length (CRL), biparietal diameter (BPD), head circumference (HC), and abdominal circumference (AC) were made at specified intervals of 2 to 3 weeks (between 6 to 8 weeks [conceptual age] and delivery) in 20 normal fetuses with known dates of conception. Values for the HC-AC ratio and the estimated fetal weight were also obtained from these data. Measurements of CRL were similar to those reported previously, except in those cases in which the follicular phase was prolonged or the fetal growth potential was reduced. Mathematical modeling demonstrated that the linear-cubic model was optimal for the BPD and HC growth curves, the linear model for the AC, and the linear-quadratic model for fetal weight. The HC-AC ratio could not be modeled adequately because of significant individual variability. Optimal models for average longitudinal growth curves were determined for the BPD, HC, AC, and fetal weight from individual growth curves. These average longitudinal curves were similar in shape, mean values, and variability to those obtained in previous cross-sectional studies. Statistical analysis indicated that the coefficients of the average longitudinal curves are not likely to change by more than 5% to 15% if the size of the sample is increased very significantly. These results indicate that the average longitudinal growth curves are good estimators of the true population growth curves.

Blood Lipids in Children: Age-Related Patterns and Association with Body-Fat Indices: Project HeartBeat!

BACKGROUND Longitudinal data on the normal development of blood lipids and its relationships with body fatness in children and adolescents are limited. Objectives of the current analysis were to estimate trajectories related to age for four blood lipid components and to examine the impact of change in body fatness on blood lipid levels, comparing estimated effects among adiposity indices, in children and adolescents. METHODS Three cohorts, with a total of 678 children (49.1% female, 79.9% nonblack) initially aged 8, 11, and 14 years, were followed at 4-month intervals (1991-1995). Total cholesterol, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglyceride levels were determined in blood samples taken following fasting. Body fatness was measured by five adiposity indices-BMI; percent body fat (PBF); abdominal circumference; and the sums of six and of two skinfold thicknesses. Trajectories of change in blood lipid levels from ages 8 to 18 years were estimated by gender and race. The impact of change in body fatness on lipid levels was evaluated for each index, adjusting for gender, race, and age. RESULTS All lipid components varied significantly with age. Total cholesterol decreased by approximately 19 mg/dL from ages 9 to 16 years in girls and more steeply from ages 10 to 17 years in boys. LDL-C decreased monotonically, more steeply in boys than in girls. It was higher among nonblacks than among blacks. HDL-C increased monotonically in girls, mainly from ages 14 to 18 years, but fluctuated sharply among boys. Levels of HDL-C were higher among blacks than among nonblacks. The levels of triglycerides increased from ages 8 to 12 years among girls and, almost linearly, from ages 8 to 18 years among boys. The levels of triglycerides were higher among nonblacks than among blacks. Increase in body fatness was significantly associated with increases in total cholesterol, LDL-C, and triglyceride levels. Significant interactions between the adiposity indices (except for BMI) and gender indicated smaller impacts of change in body fatness on total cholesterol and LDL-C in girls than in boys. The estimated impact on triglycerides was weaker among blacks than among nonblacks, except for PBF. Change in body fatness was negatively associated with HDL-C. The results remained essentially unchanged after adjustments for energy intake, physical activity, and sexual maturation. CONCLUSIONS Patterns of change with age in blood lipid components vary significantly among gender and racial groups. Increase in body fatness among children is consistently associated with adverse change in blood lipids. Evaluation of blood lipid level should take into account variation by age, gender, and race. Intervention through body-fat control should help prevent adverse lipid levels in children and adolescents.

Cigarette smoking exacerbates and its cessation ameliorates renal injury in type 2 diabetes.

Background: Patients with type 2 diabetes and macroalbuminuria generally experience progressive glomerular filtration rate (GFR) decline despite angiotensin‐converting enzyme inhibition (ACEI) and blood pressure (BP) control but this therapy generally stabilizes GFR in those without macroalbuminuria. Cigarette smoking exacerbates GFR decline in patients with type 2 diabetes and macroalbuminuria despite ACEI and BP control; whether this therapy prevents nephropathy progression in nonmacroalbuminuric type 2 diabetic smokers is unknown. Methods: We determined the course of urine excretion of indices of renal injury that distinguished patients with type 2 diabetes with and without macroalbuminuria but with normal plasma creatinine who were prospectively followed 6 months while receiving ACEI and BP control. We compared this course in nonsmokers and smokers with normo‐, micro‐, and macroalbuminuria (n = 157) and in response to smoking cessation in a separate cohort (n = 80) with microalbuminuria. Results: Urine excretion of transforming growth factor &bgr;‐1 (UTGF&bgr;V) increased in macroalbuminuric but not in nonmacroalbuminuric nonsmokers and UTGF&bgr;V rate was higher in smokers than nonsmokers within each albuminuria group. In the separate microalbuminuric cohort, the rate of UTGF&bgr;V change for quitting smokers was not different from nonsmokers (0.093 versus −0.123 ng/g of creatine/week, P = not significant) but that for nonquitting smokers (0.970) was higher than nonsmokers (P = 0.017). Conclusions: Patients with type 2 diabetes who are at high risk compared with low risk for nephropathy progression have progressive renal injury as measured by increasing UTGF&bgr;V. Cigarette smoking exacerbates renal injury in type 2 diabetes despite BP control and ACEI, but its cessation in those with microalbuminuria ameliorates the progressive renal injury caused by continued smoking.

Effects of methods of collection and storage on nutrients in human milk

The effects of collection technique, storage container, and the duration and temperature of storage on selected nutrient concentrations in mature human milk were evaluated. Milk samples were collected during the fourth week of lactation from women 20-35 years of age by hand expression or suction. Greater volumes and fat concentrations were observed in milks collected by suction. Vitamin A, zinc, iron, copper, sodium, and protein nitrogen concentrations were not affected by storage of milk in either pyrex or polypropylene containers for up to 24 h. The storage temperature had a significant effect on protein nitrogen and ascorbic acid concentrations. These findings indicate that collection methods and storage procedures used for comparatively brief periods will affect the concentrations of selected nutrients of mature human milk. Specific recommendations are made for the collection and storage of milk.

Development of Cardiovascular Risk Factors From Ages 8 to 18 in Project HeartBeat! Study Design and Patterns of Change in Plasma Total Cholesterol Concentration

BACKGROUND Project HeartBeat! is a longitudinal study of the development of cardiovascular risk factors as growth processes. Patterns of serial change, or trajectories, from ages 8 to 18 years for plasma total cholesterol concentration (TC) and percent body fat illustrate the design and synthetic cohort approach of the study. METHODS AND RESULTS Six hundred seventy-eight children (49.1% female, 20.1% black) entered the study at ages 8, 11, and 14 years and were followed up with examinations every 4 months for < or = 4 years. Multilevel analysis demonstrated trajectories for population mean values of TC and percent body fat in sex-specific synthetic cohorts from ages 8 to 18 years. Polyphasic patterns of change in TC were confirmed, with notable sex differences in age patterns and with minimum mean values of TC of 3.85 mmol/L for females and 3.59 for males. As illustrated by data for males, the approximate 75th percentile values of mean TC ranged from 4.78 mmol/L at its early peak to 4.06 at its late-teen nadir. Percent body fat exhibited a trajectory closely parallel with that for TC only for males and appeared to be unrelated for females. CONCLUSIONS The polyphasic trajectory for TC from ages 8 to 18 years differs between females and males, indicates marked age variation in 75th percentile values and, in males only, closely parallels the trajectory for percent body fat. These and other results indicate the value of both follow-up every 4 months across age intervals to detect rapid risk factor change and the synthetic cohort approach for gaining new insights into the dynamics and possible determinants of this change from ages 8 to 18 years.

Synthetic pyrethroid insecticides: a dermatological evaluation.

Synthetic pyrethroids are lipophilic insecticides whose biological activity seems to be directly related to their chemical structure. In this investigation differences in cutaneous sensation were detected by human participants between synthetic pyrethroids with a cyano group in the (S)-configuration of the 3-phenoxybenzyl alcohol of their molecular structure (fenvalerate) and those that do not (permethrin). A strong relation was noted between insecticidal potency and degree of induced cutaneous sensation for the alpha-cyano and non-cyano pyrethroids, with a prominent difference between the two. No sensation was observed by any of the same participants on topical exposure to the inert ingredients of these agents. A linear correlation between concentration and degree of induced dysaethesia was observed for both pyrethroids. Regressing the cutaneous sensation on the common logarithm of concentration resulted in a regression equation of Y = 84.0 + 31.0X1 for fenvalerate and Y = 27.5 + 15.8X1 for permethrin. A highly efficacious therapeutic agent for pyrethroid exposure was noted to be dl-alpha tocopherol acetate. An impressive degree of inhibition of paraesthesia resulted from the topical application of vitamin E acetate, with a therapeutic index of almost 100%.