Changes in rod sensitivity through adulthood.

Absolute thresholds of 23 subjects 19-61 years of age were determined for three wavelengths at six retinal eccentricities in the horizontal meridian (2.5 degrees-30 degrees). The raw data were corrected for prereceptoral light losses that may be age-dependent. Lens density was estimated for each subject by comparing scotopic spectral sensitivity with the absorption spectrum of rhodopsin. Macular pigment density was estimated by comparing macular sensitivity with peripheral sensitivity. Average dark-adapted pupil size at each age was taken from published values. After correction for these prereceptoral light losses, changes in rod sensitivity with age were not significant at any retinal locus tested.

Characterization of the electroretinographic scotopic B-wave amplitude in diabetic and normal subjects.

The intensity-response function of the scotopic b-wave of the electroretinogram may be a useful device for monitoring patients with retinal disease. Three models were evaluated that describe this function in 152 patients with diabetic retinopathy of varying severity and in 40 nondiabetic comparison subjects. The models considered were the Naka-Rushton equation fit to all 21 data points collected, the Naka-Rushton equation fit to the data points below the "second limb" of the function, and a log-linear fit only to data at the nine lowest intensities. In addition, the b-wave amplitude at each intensity tested was evaluated individually. Model parameters and amplitude measurements were compared with respect to (1) their ability to distinguish diabetic from nondiabetic subjects determined from the area under the receiver operating characteristic curve and (2) their correlation with retinopathic severity, graded in a standard fashion in fundus photographs. When all the parameters of each model were used in combination, there were no significant differences among the models with either evaluation criterion. Furthermore, b-wave amplitudes at midrange intensities (near -2.2 log cd-sec/m2) did approximately as well as any model.

Changes of visual sensitivity caused by on- and off-transients.

The effects of abrupt increases and decreases of light in one part of the retina on sensitivity in an adjacent part of the retina were studied under low scotopic conditions near absolute threshold. The basic finding is that a brief annular surround decreases sensitivity to test spots occurring near the time of its onset or its offset, but that the surround increases sensitivity to test spots occurring the first few hundred milliseconds following its offset. If the annulus is presented in one eye and the test flash to the other, annulus onset reduces sensitivity, but annulus offset has almost no effect on thresholds in the contralateral eye. In fully dark-adapted observers, absolute sensitivity is somewhat greater when the test flashes are preceded by a flashed surround than when they are presented alone. These results challenge the idea that sensitivity to these stimuli is limited by an irreducible level of noise in the dark and under dim illumination.

Rod-cone interaction in monocular but not binocular pathways.

Photopic background stimulation elevates scotopic increment thresholds (rod-cone interaction) at moderate background levels when both test and concentric disk-background stimuli enter the same eye (monocular condition) but not when they enter different eyes (dichoptic condition). Only when background levels are made extremely high is there any measurable dichoptic interaction, and this interaction does not resemble that observed monocularly. Rod-cone interaction, as usually studied, is a property of monocular pathways in human vision.

Focused obstetrical clinic for active duty junior enlisted service women: model for improved outcomes.

OBJECTIVE: To evaluate the utility of an interdisciplinary clinic in improving perinatal outcomes for all pregnant patients of junior enlisted rank (E4 and below) in response to previous reports that this group is at higher risk for adverse outcomes. METHODS: The study population included all junior enlisted active duty patients (E4 and below) delivering between January 1, 1993, and June 30, 1996. Outcomes for patients receiving care in a focused active duty obstetrical clinic were compared with outcomes in similar cohorts of senior active duty patients (E5 and above) and non-active duty pregnant patients. Evaluation was based on perinatal outcomes, including chorioamnionitis, postpartum hemorrhage, intrauterine growth retardation, cesarean delivery, preterm delivery rates (< 37 weeks), postterm delivery rates (> 41 weeks), postpartum days, mean gestational age at delivery, mean delivery weights, Apgar scores at 1 and 5 minutes, preeclampsia, and premature labor. Variables with potential to confound perinatal outcomes were also studied. Confounding variables included tobacco use, gestational diabetes, chronic hypertension, thyroid disease, history of substance abuse, and alcohol use. Power analysis accomplished before initiation of the study showed adequate sample size (> 240 patients in each group) to demonstrate statistically different rates of preterm delivery. Statistical analysis was done using the chi 2 test for categorical variables and Student's t test for continuous variables. RESULTS: There were no statistical differences between junior active duty patients, senior active duty patients, and non-active duty patients in preterm delivery and other outcome variables. CONCLUSION: The focused obstetrical clinic, conducted for junior enlisted soldiers by a senior nurse practitioner, appears to provide an intervention that ensures perinatal outcomes equal to those of both the non-active duty and the senior active duty population.

The female athlete triad: prevalence in military women.

The objective of this study was to define the prevalence of the female athlete triad, i.e., the simultaneous occurrence of disordered eating, amenorrhea, and osteoporosis, in military women. A total of 423 active duty female soldiers participated in a three-part prospective, cross-sectional study. Part 1 entailed completing the Eating Disorder Inventory and a clinical interview with those women "at risk" for an eating disorder. Part 2 consisted of a clinical evaluation and laboratory studies of any woman with menstrual irregularities. Part 3 evaluated the bone mineral density of all women meeting the inclusion criteria for parts 1 and 2 using dual-energy X-ray absorptiometry. Of the 423 active duty women who participated in the study, no subject exhibited the full female athlete triad. Thirty-three women (8%) had an eating disorder and 109 women (26%) were at risk for an eating disorder. Our results suggest that the female athlete triad is not a clinically significant problem for the Army.

Infant saccadic eye movements to visible and previously visible targets.

Recent evidence has shown that 1- and 2-month-old infants localize a peripheral target by means of a series of saccades. Step size in a series was directly related to target distance, but within a localizing series did not vary appreciably as the line of sight approached the target. The current study examined whether, during localization of a peripheral target, step size and number of steps were determined prior to the first saccade in a localizing series. 2-month-olds viewed peripheral targets which either remained on (continuous condition) or were extinguished (interrupted condition) prior to target localization. It was found that on the majority of trials a series of saccades was made toward the target hemifield. In both conditions the size of each saccade in a multiple saccadic series was approximately equal within a given trial, but varied with initial target distance. Multiple saccades on both continuous and interrupted trials were similar in form, differing only in the total extent of eye rotation. This suggests that a similar oculomotor program was operating under both conditions.

Allergy history does not predict skin test reactivity in asthmatic children.

We prospectively assessed how well patient report of allergy to cat, dust mite, and grass predicted the results of skin prick testing to those allergens in 95 asthmatic children. Children between 4 and 18 years old with physician-documented asthma provided a detailed standardized allergy history and then underwent skin prick testing. The children were categorized by asthma severity. The diagnostic accuracy, which was the primary outcome measure, as well as sensitivity, specificity, and positive and negative predicted values were calculated for allergy history with regards to skin test reactivity. The diagnostic accuracy of allergy history in identifying skin test reactivity was 65%, 50%, and 56% for cat, dust mite, and grass, respectively. Asthma severity did not affect the diagnostic accuracy. Allergy history was a poor predictor of skin test reactivity in this group of asthmatic children.

A single dose of intramuscularly administered dexamethasone acetate is as effective as oral prednisone to treat asthma exacerbations in young children.

OBJECTIVE: To evaluate whether a single dose of intramuscularly administered dexamethasone acetate (IM Dex) was as safe and effective as a 5-day course of oral prednisone (PO Pred) in the treatment of young children with mild-moderate exacerbations of asthma. STUDY DESIGN: A prospective, randomized, investigator-blinded study was done in a tertiary care medical center in children (6 months to 7 years of age) who required corticosteroids to treat mild-moderate asthma exacerbations as outpatients. Patients were randomized to receive either a single dose of IM Dex ( approximately 1.7 mg/kg) or PO Pred ( approximately 2 mg/kg/d for 5 days). Clinical asthma score, behavioral changes, albuterol use, and tolerance of the medication were recorded in a home diary for 7 days. Cortisol/creatinine ratios on first morning void urine samples were obtained on day 14. The primary outcome measures were changes in clinical asthma score through day 5 and tolerance of the medication. RESULTS: Fifteen patients in the IM Dex group (mean age 37 months) and 17 in the PO Pred group (mean age 36 months) completed the study. Clinical asthma score improved significantly in both groups during the first 5 days of therapy, and no significant difference was seen in the rate of improvement between the 2 groups. Three children refused more than 75% of their prednisone doses, and another 4 missed 30% to 50% of the doses despite their parents' best efforts. The intramuscular injection caused no complications, and approximately 70% of parents in both groups stated that they would choose IM Dex to treat their child's next asthma exacerbation. CONCLUSION: In this group of children a single intramuscular injection of dexamethasone acetate was as effective as a 5-day course of PO Pred for the management of mild-moderate outpatient asthma exacerbations.

A comparison of radical retropubic with perineal prostatectomy for localized prostate cancer within the Uniformed Services Urology Research Group.

OBJECTIVE: To review and compare the outcome of patients undergoing radical retropubic prostatectomy (RRP) or radical perineal prostatectomy (RPP) for clinically localized prostate cancer. PATIENTS AND METHODS: From 1988 to 1997, 1382 men who were treated by RRP and 316 by RPP were identified from databases of the Uniformed Services Urology Research Group. The following variables were assessed; age, race, prostate-specific antigen (PSA) level before surgery, clinical stage, biopsy Gleason sum, estimated blood loss (EBL), margin-positive rate, pathological stage, biochemical recurrence rate, short and long-term complication rates, impotence and incontinence rates. To eliminate selection bias, the analysis was concentrated on pairs of patients matched by race, preoperative PSA level, clinical stage and biopsy Gleason sum. RESULTS: In the 190 matched patients there were no significant differences between the RRP and RPP groups in either organ-confined (57% vs 55%), margin-positive (39% vs 43%), or biochemical recurrence rates (12.9% vs 17.6% at a mean follow-up of 47.1 vs 42.9 months), respectively. The mean EBL was 1575 mL in the RRP group and 802 mL in the RPP group (P < 0.001). The only significant difference in complication rates was a higher incidence of rectal injury in the RPP group (4.9%) than in the RRP group (none, P < 0.05). CONCLUSIONS: In similar populations of patients, RPP offers equivalent organ-confined, margin-positive and biochemical recurrence rates to RRP, while causing significantly less blood loss.