The ultrastructural response of human Leydig cells to exogenous estrogens

The effect of long term treatment with estrogens alone or along with medroxyprogesterone acetate on the Leydig cell ultrastructure was studied in testes from males undergoing surgery for sexual reassignment. The testes were fixed for electron microscopy by a perfusion method to insure uniform preservation. The morphological features were not the same in all the treated testes. Therefore, the cells found in the intertubular region were classified into three groups: (A) Leydig cells very similar to controls; (B) Absence of typical Leydig cells, but with cells having increased microfilaments, abundant smooth endoplasmic reticulum and some lipid droplets; (C) Absence of any cell type possessing abundant smooth endoplasmic reticulum, but having varying amounts of microfilaments and pigmentation. It is suggested that some of the cell types found in the intertubular region are dedifferentiated Leydig cells. This study indicates that the human testis from transsexuals of reproductive age is an appropriate model to study the indirect and direct effects of estrogens on the ultrastructure of cell types found in the human testes.

Psychological problems reported by young adults who were burned as children

This study assessed long-term psychosocial sequelae of young adult pediatric burn survivors. Subjects were 101 young adults (43 females and 58 males) between the ages of 18 and 28 years who were at least 2 years (average, 14 years) postburn at least 30% TBSA (mean = 54 +/- 20%). Educational status was 25% high school dropouts, 28% high school graduation only, 32% some college, and 5% completed college. Seventy-seven percent either worked or attended school; 28% had had a long-term partner. When assessed by Achenbach's Young Adult Self-Report (YASR) scale and compared with its published reference group, the males reported differences only in the somatic complaints, but the females endorsed significantly more externalizing and total problems, specifically withdrawn behaviors, somatic complaints, thought problems, aggressive behavior, and delinquent behavior. Despite these problems suffered by some female pediatric burn survivors, the overall outcome revealed that most pediatric burn survivors are making the transition into adulthood with minimal unexpected difficulty.

Anxiety: current practices in assessment and treatment of anxiety of burn patients

Anxiety is an affective response commonly experienced by persons after emotional and physical trauma, as well as associated with aversive medical treatments. The scientific information related to the conceptualization, assessment, and treatment of anxiety is limited. In order to develop a pilot protocol for anxiety management, nursing directors at 64 burn centers were surveyed. At 89% of the centers, anxiety measures were not used. Most of the teams assess informally through observation of patient (n=21), dialogue with patient (n=12), or both observation and dialogue with patient (n=15). Assessors of anxiety range in breadth from nurse only to the entire burn team, including pastoral care representatives and family. The class of medication most frequently endorsed in treating anxiety is the benzodiazipine, most often lorazepam (Ativan). A number of non-pharmacologic techniques are used to manage anxiety, e.g., muscle relaxation, breathing, imagery. Consideration should be given to assessing anxiety systematically, so knowledge can be gleaned and applied to conceptualization of symptom presentation and application of treatment resources.

Randomized, placebo-controlled pilot study of divalproex sodium in the treatment of acute exacerbations of chronic schizophrenia

Experimental and clinical data suggest that GABA-ergic drugs such as valproate may have a potential role in the treatment of schizophrenia. The authors designed a 21-day prospective, double-blind, randomized, placebo-controlled pilot study of divalproex sodium as add-on treatment to haloperidol in 12 hospitalized patients with acute exacerbations of chronic schizophrenia. All patients received haloperidol 10 mg/day for 3 days and 15 mg/day for the remaining 18 days. In addition, five patients were randomly assigned to receive divalproex augmentation and seven to receive placebo. The divalproex dose was adjusted to a target serum concentration of 75 microg/mL for 2 weeks; placebo replaced divalproex during the third and last weeks to determine any carryover effect. Psychiatric rating scales were administered at baseline and on days 7, 14, and 21. Although the placebo group improved with haloperidol treatment, the divalproex group demonstrated greater improvement. On day 21, the divalproex group had greater improvement from baseline on the Clinical Global Impression Scale (p < or = 0.04), Brief Psychiatric Rating Scale (p < or = 0.13), and Schedule for Assessment of Negative Symptoms scores (p < or = 0.007). After divalproex withdrawal on day 15, a carryover effect was observed during week 3. The authors concluded that the addition of divalproex sodium to standard antipsychotic drugs may prove effective in relieving the symptoms of acute schizophrenia. Future studies may benefit from the design of this pilot study. However, it is premature to apply this augmentation strategy in the clinical setting just yet because of the small sample size and the likely heterogeneity of the disorder.

On changing curricula: lessons learned at two dissimilar medical schools

Two dissimilar U.S. medical schools--the University of Pittsburgh School of Medicine and the University of Texas Medical Branch at Galveston-changed their curricula for the first two years of medical education from ones that were lecture-dominated and departmentally run to ones that are centrally governed, multi-modal, goal-oriented, and fully integrated, with mechanisms to continue curricular change into the last two years of medical education. The change at each school was in response to national education philosophy, the recommendations of the Liaison Committee for Medical Education after the most recent site visit, and faculty's and students' concerns and interests. The change process took place over a three- to four-year period at each school, involved students, faculty, and administration, and utilized task forces and retreats as communication vehicles. The barriers encountered (e.g., belief by some that the curriculum needed no change; concern over loss of departments' control) and the processes employed to overcome them and to radically change the curricula (e.g., commitment of the central administration and dean to the change, involvement of all segments of the school in the change process, appointment of department chairs on task forces, and creation of a strong curriculum committee that gave authority to faculty and students) were essentially identical. The resulting curricula were also largely similar in their main characteristics, but there were notable differences, based on the goals and concerns of the two institutions.

Evaluating the psychosocial adjustment of 2- and 3-year-old pediatric burn survivors

Very little information has been published about 2- and 3-year-old children who have experienced major burns. This study used a standardized instrument to measure the behavioral adjustment of these young burn survivors, and the results were compared with those of a nonclinical normative sample. Thirty-three pediatric burn survivors with 50%+/-28% total body surface area burns were evaluated 1.2+/-0.7 years postburn. Parental observations were assessed with the use of the Child Behavior Checklist for 2- and 3-Year-Olds, a 99-item standardized checklist designed to identify behavior problems. Forty of the questions are specific to 2- and 3-year-olds, and the scores of male and female children are not differentiated. The raw scores of the children with burns were statistically compared with the reported normative sample for this version of the Child Behavior Checklist. Pediatric burn survivors in this sample exhibited significantly more internalizing behaviors than the children in the normative group. Parents reported children who had been burned to be more depressed and to have more somatic complaints and sleep problems. Determining the relationship of behavior problems to posttrauma sequelae and preburn environmental factors would assist with the establishment of appropriate psychosocial interventions.

Imipramine treatment in pediatric burn patients with symptoms of acute stress disorder: a pilot study

OBJECTIVE

Pediatric burn patients often exhibit acute stress disorder (ASD) symptoms. Information on psychopharmacological treatment of ASD symptoms in children is scarce. This pilot study used a prospective, randomized, double-blind design to test whether thermally injured children suffering ASD symptoms benefit from imipramine.

METHOD

Twenty-five children, aged 2 to 19 years, received either imipramine or chloral hydrate for 7 days. A structured interview (clinically useful, but validity and reliability not yet established) was used to assess the presence and frequency of ASD symptoms both before treatment and 3 times during the treatment period.

RESULTS

Eleven females and 14 males participated, with a mean total burn surface area of 45% (SD = 23%) and mean age of 8 years (SD = 6). Imipramine was more effective than chloral hydrate in treating ASD symptoms (chi 2 [1, N = 25] = 5.24, p < .02). Five of 13 were positive responders to chloral hydrate (38%). Ten of 12 were positive responders to low-dose imipramine (83%).

CONCLUSIONS

This pilot study suggests a place for cautious initial use of imipramine to reduce ASD symptoms in burned children. Care must be taken to minimize cardiovascular risks in an off-label application of imipramine in children, especially those receiving additional medications.

Critical review of GABA-ergic drugs in the treatment of schizophrenia

GABA-ergic medications may have a potential role in the treatment of schizophrenia. Laboratory evidence has generally supported the ability of gamma-aminobutyric acid (GABA) to reduce dopaminergic activity and has suggested that GABA may be effective in combating hypofrontality by acting on mesoprefrontocortical tracts in patients resistant to treatment with antipsychotic drugs. Although the results of clinical trials of several GABA-ergic compounds have been inconclusive because of methodologic limitations and drug toxicity, benzodiazepines and valproate seem to be associated with favorable treatment outcomes, especially when combined with typical antipsychotic agents. This study concludes that further investigation of the use of GABA in schizophrenia is likely to improve the understanding of the psychopathology of this illness and to expand our treatment alternatives. Also provided are suggestions to enhance the design of future studies, improve the potential for favorable treatment outcomes, and assist in predicting patients' responses to GABA-ergic medications.

An approach to the timely treatment of acute stress disorder

A convergent postburn psychopharmacologic treatment for children for acute stress disorder (ASD) symptoms has not been established. Both the application of what has been learned through treatment of similar symptoms experienced by adults with posttraumatic stress disorder and the examination of safe treatment options for children led to the clinical decision to use imipramine for 25 pediatric patients with acute burns. The treatment histories of these patients were retrospectively reviewed to see if further exploration into the efficacy of imipramine was warranted. Eighty percent of the children experienced remission of hyperarousal symptoms (eg, trouble staying asleep, trouble falling asleep) and intrusive reexperiencing symptoms (eg, nightmares). Twelve percent of the children experienced a decrease in the frequency or intensity of ASD symptoms. Eight percent had no relief of ASD symptoms. Initial findings suggest that imipramine assists children who have postburn ASD symptoms by decreasing the hyperarousal and intrusive reexperiencing symptoms of ASD.

Impact of disfiguring burn scars on adolescent sexual development

It is popularly believed that disfiguring scars compromise the burned adolescent's ability to establish satisfactory dating relationships and to develop positive identities as sexually attractive people. The purpose of this study was to test that belief by obtaining information about the sexual behaviors and beliefs of adolescents who have disfiguring scars. Nineteen adolescents, ages 13 to 20 and at least 1 year postburn, completed a sexuality survey entitled What Young People Believe and Do--Revised. When compared with the available information, adolescents with disfiguring burn scars appear to have thoughts, feelings, and behaviors that are similar to those of nonburned adolescents. The severity of disfigurement as measured by numbers of affected body areas does not seem to be related to the sexual behaviors of the teenagers in this sample.

Relationship between parental emotional states, family environment and the behavioural adjustment of pediatric burn survivors

The purpose of this study was to examine the relationship between psychosocial adjustment of the burned child and characteristics of the child's family. It hypothesized that parents who perceived their children without major behavioural problems would possess supportive family values and would, themselves, be better adjusted psychologically than those parents who perceived their children as possessing multiple behavioural problems. A stratified random sampling technique was used to select 35 (29 boys, 6 girls) paediatric burn survivors, ages 9 to 18, 1-5 years post-burn, with burn sizes ranging from 3 to 92% burn. Subjects' parents were administered the Child Behaviour Checklist (CBCL), the Family Environment Scale (FES), the Impact of Events Scale (IES), and the Beck Depression Inventory (BDI). The subjects were divided into two groups on the basis of the total problem CBCL scores. i.e. troubled (T > or = 60) or untroubled (T<60). One-way ANOVA tests revealed no significant differences between the two groups in the way parents reacted to trauma (IES) and parental depression (BDI). Significant differences (p<0.01) were revealed between the two groups on FES subscales. The parents of the untroubled group scored higher on 'Cohesion' and 'Organization' and lower on 'Conflict'. These parents also scored higher (p< or =0.05) on 'Achievement Orientation'. The results indicate that work with the family to promote cohesion. to decrease conflict, to enhance stability and to promote expectation of positive achievement must he a part of the rehabilitation of the burned child.

Altered newborn gender distribution in patients with low mid-trimester maternal serum human chorionic gonadotropin (MShCG)

OBJECTIVE

to determine if the sex ratio (male/female) is altered in infants born to patients with low mid-trimester maternal serum human chorionic gonadotropin (MShCG).

STUDY DESIGN

Between 2/1/90 and 1/3/91, 3,116 patients underwent prenatal screening using second-trimester maternal serum alpha-fetoprotein (MSAFP), MShCG, and maternal serum unconjugated estriol (MSuE3). Among these, there were 132 patients with low second-trimester MShCG (< 0.4 MoM), normal MSAFP and MSuE3. The gender distribution of these term, normal newborns was compared to that of 237 controls, matched for race, maternal age, and referral source and delivered at term to mothers with normal mid-trimester MSAFP, MSuE3, and MShCG. The gender distribution of these two groups of newborns was also compared to that of 78 term newborns from the same obstetrical population delivered to mothers with second-trimester MShCG > 2.5 MoM and normal MSAFP and MSuE3. All patients had a complete obstetrical history.

RESULTS

Forty-nine percent of the controls were male vs. 62% of the group with slow second-trimester MShCG (P < .01). Within the group with low MShCG, 59% of infants were male when the MShCG was between 0.19 and 0.4 MoM (A) and 80% when the MShCG was < 0.2 MoM (B) (control vs. A vs. B P < .005). The sex ratio in the high-MShCG group was similar to control.

CONCLUSION

The data suggest that gender distribution is different from normal in patients with low mid-trimester MShCG.

Policy development for the control of sex-offending behavior

Sexual violence is among the foremost problems that our society faces today. Addressing this problem will require more direct public education, effective and accessible resources for victims, punishment for offenders, and treatment of offenders to prevent recidivism. Although the 74th Texas legislative session began a concentrated approach to addressing this problem, further legislation is needed to provide a cost-effective method to increase public safety from sexual violence over the long term.

Chorioamnionitis does not affect fetal urine production in patients with premature rupture of membranes

The objective of this study was to evaluate fetal urine production rate in patients with premature rupture of membranes in the presence or absence of chorioamnionitis and to determine its clinical usefulness. Fetal urine production was evaluated in 30 women between 24 and 39 weeks' gestational age with ruptured membranes. Fetal bladder measurements were determined every 3-5 min for 30-90 min. Chorioamnionitis was defined by both clinical criteria and histological examination of the placenta. The last determination of fetal urine production rate prior to delivery was compared in patients with and without histologic and/or clinical chorioamnionitis. Fetal urine production rate was corrected for gestational age using birth weight prior to analysis. A total of 96 assessments of fetal urine production were performed (range 1-16 per patient). Twelve subjects (40%) had no evidence of chorioamnionitis (group 1), 10 (33%) had histologic chorioamnionitis alone (group 2), and eight (27%) had both clinical and histologic chorioamnionitis (group 3). The mean (+/- SD) urine production rates in these groups were 9.43 +/- 3.15 ml/kg/hr, 10.65 +/- 3.43 ml/kg/hr, and 9.97 +/- 2.81 ml/kg/hr, respectively. The difference in fetal urine production rate between the three groups was not statistically significant. A power analysis revealed that individual group sizes were adequate to document a 50% increase in fetal urine production rate with a type II error of < 10%. There were no documented cases of fetal infection based on neonatal cultures. The presence of histologic or clinical chorioamnionitis does not significantly affect fetal urine production in patients with premature rupture of membranes. The prospective assessment of fetal urine production rate does not appear to be clinically useful as an early indicator of chorioamnionitis.

Comorbidity of gender dysphoria and other major psychiatric diagnoses

Previous studies suggest that many transsexuals evidence an Axis I diagnosis according to the DSM-IV classification (e.g., psychoses, major affective disorder). The current study examined retrospectively the comorbidity between gender dysphoria and major psychopathology, evaluating the charts of 435 gender dysphoric individuals (318 male and 117 female). All had undergone an extensive evaluation, addressing such areas as hormonal/surgical treatment, and histories of substance abuse, mental illness, genital mutilation, and suicide attempts. In addition, a subgroup of 137 individuals completed the MMPI. Findings revealed over two thirds were undergoing hormone reassignment, suggesting a commitment to the real-life cross-gender process. One quarter had had problems with substance abuse prior to entering treatment, but less than 10% evidenced problems associated with mental illness, genital mutilation, or suicide attempts. Those completing the MMPI (93 female and 44 male) demonstrated profiles that were notably free of psychopathology (e.g., Axis I or Axis II criteria). The one scale where significant differences were observed was the Mf scale, and this held true only for the male-to-female group. Psychological profiles as measured by the MMPI were more "normal" in the desired sex than the anatomic sex. Results support the view that transsexualism is usually an isolated diagnosis and not part of any general psychopathological disorder.

Acetaminophen in the management of background pain in children post-burn

This retrospective review evaluated the pain management of 395 acutely burned pediatric patients who were treated by a pain management protocol emphasizing acetaminophen as the initial medication to control background pain. Pain was assessed by using standardized instruments based on observations by patients, nurses, and parents. Morphine was added when scheduled acetaminophen (10-15 mg/kg/4 hr) did not control background pain. Fifty percent of the children received only acetaminophen to control background pain. Younger children and children with the smallest burns, regardless of age, were likely to be managed with acetaminophen alone. Most peak serum concentrations of acetaminophen were less than 10 micrograms/mL. When needed, children also received medication for painful procedures, anxiety, and posttraumatic stress symptoms. These additional medications were not more frequently given to children receiving only acetaminophen for background pain. These data suggest that acetaminophen is a safe, useful medication for the control of post-burn background pain in some children.

Early gestational glucose screening and gestational diabetes

OBJECTIVE

The purpose of this study was to determine the benefit of early glucose screening prior to 24 weeks' gestation in detecting gestational diabetes.

STUDY DESIGN

A retrospective analysis of 329 patients who received both early and complete prenatal care at the University of Illinois was performed. A 50-g, 1-hour glucose screen was performed at the first prenatal visit. An abnormal glucose screen, defined as blood sugar > 135 mg/dL, was followed by a 100-g, 3-hour glucose tolerance test. Gestational diabetes was defined as the presence of two or more abnormal values on the three-hour test. This protocol was repeated again at 28 weeks in all patients except those diagnosed as diabetic by having abnormal early three-hour tests. Data collected included maternal age, race, gravidity, presence of risk factors, pregnancy weight gain at glucose testing and delivery, neonatal birth weight and trauma. Data were analyzed using analysis of variance and chi 2 testing, with P < .05 considered significant.

RESULTS

Gestational diabetes was diagnosed in 20 (6.1%) of the study patients. Eight (40%) of the gestational diabetics in the study population were detected with the early screening protocol. Factors associated with early detection of glucose intolerance included maternal age > 30 years (P < .001), black race (P < .001) and the presence of risk factors (P < .0001). Poor pregnancy weight gain was associated with the late development of glucose intolerance (P < .001). Gestational diabetes was subsequently diagnosed in 16% (6/38) of those patients who had, on early testing, an elevated one-hour glucose screen and negative three-hour glucose tolerance test when testing was repeated in the third trimester.

CONCLUSION

Early gestational glucose screening may be beneficial in detecting gestational diabetes in patients over 30 years old who are black or who have risk factors for diabetes. Consideration should be given to repeat glucose testing in the early third trimester in patients with false positive early one-hour screening tests.

Positive self-regard as a coping mechanism for pediatric burn survivors

Pediatric burn survivors are reported to present optimistic pictures of themselves; it has been suggested that their reports of high self-esteem may reflects a coping mechanism. The purpose of this study was to compare burned children's self-perceptions of competence and adequacy to normative population with the use of two standardized instruments. A random sample of 32 pediatric burn survivors was administered two standardized instruments: the Piers-Harris and the Harter Self-Perception Profiles for children and adolescents. Paired t tests revealed significantly higher self-concepts by the burned children than the nonclinical reference groups on five of the six Piers-Harris clusters and on two of the nine Harter Self-Perception Profiles domains. Also, the relationship between the children's perceived self-worth in each domain, and the importance they attributed to that domain, indicate that the burned children are satisfied with themselves in those areas they perceive as important. Results from both tests suggest that the burn survivors' report of positive self-esteem may reflect a necessary defense mechanism in the adjustment process, which should be supported by the burn team.

The Jarisch-Herxheimer reaction in pregnancy: a nursing perspective

The Jarisch-Herxheimer reaction is a systemic event that can occur after the first dose of penicillin administration during treatment of syphilis. This article presents a case report of the Jarisch-Herxheimer reaction in a woman who was treated for syphilis at 27 weeks gestation. The proposed pathophysiology of the reaction is described, and complications of this reaction during pregnancy are reviewed. Recommendations for the nursing care of women treated for syphilis are provided.

Diminished adaptive behaviors among pediatric survivors of burns

Life for pediatric survivors of burns appears difficult to most observers. In an assessment by use of the Child Behavior Checklist (CBCL), survivors' parents reported that approximately 30% of the children had significant problems. The Vineland Adaptive Behavior Scales were used to gather further information concerning the children's personal and social sufficiency and functioning. Thirty-four pediatric burn survivors (28 boys and 6 girls, ages 9 to 19, 1 to 5 years after burn, with burn sizes ranging from 3% to 92% total body surface area) were selected by use of a stratified random sampling technique. Ten of the 14 scales are significantly different (p < 0.05, paired t) from the reference population in the Vineland manual. The Vineland scores indicate that parents view their burned children as being less personally or socially sufficient. Subjects with significant behavior problems as measured by use of the CBCL (T score > or = 60) differed from their peers with fewer problems by having less overall adaptive behavior (p = 0.07), fewer coping skills (p = 0.06), and significantly more maladaptive behavior (p = 0.005). The Vineland adaptive behavior domains correlated positively with the CBCL total competence scores, whereas the Vineland maladaptive behavior correlated positively with the CBCL total behavior score. Although it supports previous findings that parents of burned children see them as having problems after burn, this study elaborates on and differentiates among their difficulties in adapting to their life situations. These findings not only affirm the importance of attending to parental perceptions of burned children but also identify specific areas to be targeted for psychosocial rehabilitation of burned children.

Inconsistencies in psychosocial assessment of children after severe burns

Health care providers usually except children with severe burns to have psychosocial problems due to the severity of the injuries and resulting deformities. To test the validity of that expectation, 72 children (43 boys, 29 girls) who had suffered severe burns were assessed at least 1 year after burn injury for behavior problems and competence, by use of the 1991 Achenbach questionnaires: Child Behavior Checklist (CBCL), Youth Self-Report, and Teacher Report Form. The scores on each questionnaire then were compared by use of paired t tests. Also, the scores of the patient population were compared with those of the nonreferred reference populations provided by Achenbach. Compared with the Teacher Report Form and Youth Self-Report, the CBCL revealed a statistically significant (p < 0.05) greater number of behavior problems and lower level of competence for all age groups and both sexes. Item analysis revealed in most instances excess endorsement of specific items on all scales for the patient population compared with their respective reference populations, but more items were endorsed on the CBCL. These results could be explained by increased parental sensitivity to problem behavior or decreased competence of their children after severe burns. Further studies are needed to understand the discrepancies between the CBCL and the other scales.

A placebo-controlled evaluation of the effects of buspirone on smoking cessation: differences between high- and low-anxiety smokers

One hundred one smokers were divided into high and low trait anxiety groups on the basis of a normalized score on the Profile of Mood States Anxiety/Tension Scale and were randomly assigned to receive buspirone or placebo in a double-blind fashion. After a 1-week baseline, smokers were exposed to an 8-week drug and behavioral intervention involving buspirone or placebo (up to 60 mg/day) with concurrent group cognitive behavioral intervention. All smokers were to quit smoking on the target date, set at 4 weeks after the program began. Medication was provided for an additional 4 weeks after group treatment ended. The results showed that buspirone had a beneficial effect on smoking abstinence but only among smokers who were already relatively high in anxiety and only for as long as the drug was available. Moreover, when provided to smokers who were relatively low in anxiety, the drug appeared to interfere with abstinence, although these effects also reversed when the drug was withdrawn. These effects were associated with an attenuation of the expected rise in anxiety before the quit date and its actual reversal thereafter, but only in the buspirone high-anxiety group. One-month abstinence averaged 88, 61, 60, and 89% for the buspirone high-anxiety, placebo high-anxiety, buspirone low-anxiety, and placebo low-anxiety groups, respectively. By 12 months, abstinence for the buspirone and placebo high- and low-anxiety groups fell to 12, 23, 41, and 36%, respectively. No differences were observed for measures of self-efficacy, symptoms of withdrawal, medication side effects, or compliance.

Catalase activity as a predictor of amniotic fluid culture results in preterm labor or premature rupture of membranes

OBJECTIVE

To evaluate catalase activity as a rapid predictor of microbial invasion of amniotic fluid (AF).

METHODS

The study population consisted of 74 patients before 36 weeks' gestation with preterm labor or premature rupture of membranes (PROM). Subjects were excluded if there was evidence of clinical chorioamnionitis or fetal distress at admission. Amniocentesis was done within 24 hours of admission, and the AF was cultured for aerobic and anaerobic bacteria and for Mycoplasma species. All AF samples were Gram stained, and slides were examined by microbiology technologists. Amniotic fluid catalase activity was measured immediately after amniocentesis using a commercially available kit. The sensitivity of the Gram stain and catalase activity were compared using McNemar exact test.

RESULTS

Amniotic fluid cultures were positive in 12 of 37 (32%) patients presenting with preterm labor and in 21 of 37 (56%) patients with PROM. Catalase activity was significantly more sensitive than Gram stain in detecting positive AF cultures in cases of PROM (P < .001) and preterm labor (P < .04).

CONCLUSION

Catalase activity is a simple, rapid test that is useful in identifying subclinical intra-amniotic infection in patients with preterm labor or PROM.

Effect of amniotic fluid volume on ultrasonic fetal weight estimation

We evaluated the relationship between the amniotic fluid index and the accuracy of fetal weight estimation using ultrasonography. Six hundred and sixty-four patients, between 20 and 42 weeks' gestational age, who were delivered within 1 week of a sonographic examination were studied. Five formulas for estimating fetal weight also were studied. Systematic and random errors in predicting birth weight were analyzed relative to birth weight and amniotic fluid index. The accuracy of sonographic fetal weight estimation was independent of amniotic fluid index across all gestational ages and birth weights. Each of the five formulas had similar error percentages, and no significant differences were detected. Predicted fetal weight was significantly underestimated with each of the formulas studied, a finding that was also independent of birth weight and amniotic fluid index. We conclude that ultrasonography can be used reliably to estimate fetal weight in patients with altered amniotic fluid volumes.

Ultrasonographic detection of abnormal fetal growth with the gestational age-independent, transverse cerebellar diameter/abdominal circumference ratio

OBJECTIVES

We prospectively evaluated the accuracy of a gestational age-independent method of detecting abnormal growth, the transverse cerebellar diameter/abdominal circumference ratio, and compared this with standard ultrasonographic methods of growth assessment.

STUDY DESIGN

We prospectively studied 825 low-risk obstetric patients and 250 patients having risk factors for fetal macrosomia (n = 92) or growth retardation (n = 158). Measured fetal parameters included the biparietal diameter, head circumference, transverse cerebellar diameter, abdominal circumference, and femur length. The estimated fetal weight, head circumference/abdominal circumference, cerebellar diameter/abdominal circumference, and femur length/abdominal circumference ratios were calculated. Reference curves for these parameters were created from a cross-sectional analysis of the low-risk group. Univariate analysis was used to determine the sensitivity, specificity, predictive values, and odds ratios of each individual parameter in identifying a small- or large-for-gestational-age infant. A multivariate logistic regression model with a variable selection procedure was then used to determine whether significance remained when we controlled for other parameters.

RESULTS

Within the low-risk group, the transverse cerebellar/abdominal circumference ratio was gestational age independent between 14 and 42 weeks with a mean of 13.68 +/- 0.96. A value exceeding 2 SD of the mean was significantly associated with birth or a small-for-gestational-age infant, being abnormal in 98% and 71% of asymmetrically and symmetrically growth-retarded infants, respectively. Significance was maintained in the multivariate regression model. The ratio was not helpful in detecting the large-for-gestational-age infant.

CONCLUSION

The fetal transverse cerebellar diameter/abdominal circumference ratio is an accurate, gestational age-independent method of identifying the small-for-gestational-age but not the large-for-gestational-age infant.

Intrapartum fetal subcutaneous tissue/femur length ratio: an ultrasonographic clue to fetal macrosomia

OBJECTIVE

Our purpose was to compare the accuracy of ultrasonographic intrapartum measurement of fetal abdominal circumference, estimated fetal weight, and fetal subcutaneous tissue/femur length ratio in predicting large-for-gestational-age fetuses.

STUDY DESIGN

A cross-sectional analysis of 173 normal patients delivered of normal, appropriate-for-gestational-age infants (group 1) was performed to determine the normal changes of standard fetal biometric parameters and subcutaneous tissue throughout pregnancy. Measurements of fetal subcutaneous tissue were made at the level of the femoral diaphysis. A second group of 101 well-dated patients had these measurements obtained within 24 hours of delivery (group 2). Large for gestational age was defined as a birth weight > 90th percentile for gestational age. The sensitivity and specificity for prediction of large for gestational age of an intrapartum measurement of an abdominal circumference > 90th percentile, estimated fetal weight > 90th percentile, and fetal subcutaneous tissue/femur length ratio > 2 deviations of the mean was calculated.

RESULTS

In group 1 the mean gestational age was 31.4 +/- 5.4 weeks (range 17 to 41 weeks). The femur length, abdominal circumference, and fetal subcutaneous tissue correlated well with gestational age (p < 0.0001). The fetal subcutaneous tissue/femur length ratio was stable throughout pregnancy, with a mean of 0.05 +/- 0.014 (range 0.02 to 0.09, R2 0.09). In group 2 mean gestational age was 38 +/- 2.5 weeks (range 30 to 42 weeks). Mean birth weight was 3280 +/- 740 gm (range 1513 to 4801 gm). Nineteen (19%) fetuses were large for gestational age. Significant differences were found between the appropriate- and large-for-gestational-age fetuses for birth weight, abdominal circumference, estimated fetal weight, and fetal subcutaneous tissue/femur length ratio (p < 0.0001). The sensitivity and specificity of the fetal abdominal circumference, estimated fetal weight, and fetal subcutaneous tissue/femur length ratio were 44% and 98%, 68% and 85%, and 82% and 96%, respectively.

CONCLUSION

The fetal subcutaneous tissue/femur length ratio is a gestational age-independent parameter that has a greater sensitivity than the fetal abdominal circumference or estimated fetal weight formula for the intrapartum identification of large-for-gestational-age fetuses.

Stimulatory effects of immunoreactive growth hormone on proliferation of a human lymphocyte cell line

Previous studies have indicated the secretion of a growth hormone-like molecule by the lymphocyte T-cell line, H9. We examined the autocrine growth-promoting effects of this T-cell derived factor. H9 conditioned medium stimulates proliferation of H9 cells themselves in a dose-dependent fashion. This growth stimulating effect could be blocked by anti-human growth hormone antiserum, but could not be simulated by addition of growth hormone only or interleukin 2 only, or a combination of both. Dexamethasone inhibited H9 growth in low nutrient culture conditions and seemed to somewhat offset the growth promoting effect of the hGH-like molecule. However, the exact role played by dexamethasone in H9 cell growth and death, as well as the exact mechanism by which the hGH-like molecule exerted its growth-promoting action, remain to be elucidated.

Treatment of gender dysphoria (transsexualism)

Gender dysphoria, or transsexualism, is a condition involving incongruity between an individual's anatomic sex and personal sense of gender identity. Only in the last 15 years have Standards of Care been established and a professional organization developed to bring definition and consistency to the field (Harry Benjamin International Gender Dysphoria Association). A typical course of treatment lasts several years and includes psychological/psychiatric evaluations, completion of the "real life" test, administration of hormone therapy to create desired secondary sex characteristics, and finally sex reassignment surgery. As the field has developed and health-care professionals and the public have become more aware, increasing numbers of individuals are coming forward to seek evaluation and treatment. Published follow-up studies documenting long-term outcome are needed now. Current intervention techniques have progressed beyond the "experimental" stage and can be regarded as accepted medical practice.

Two-minute miniprep method for plasmid DNA isolation

An extremely rapid method, INSTA-PREP, has been developed to prepare plasmid DNA from 1 to 3 mL miniprep Escherichia coli bacterial cultures. Direct extraction of plasmid DNA from E. coli bacterial cells is achieved by a two-phase solution consisting of phenol-chloroform-isoamyl alcohol and water or buffer with efficient separation of the phases by centrifugation in the presence of the INSTA-PREP gel barrier material. Processing time, from E. coli culture to usable plasmid DNA, is two minutes or less per sample. Supercoiled plasmid DNA yields ranged from 3 to 10 micrograms per mL of culture depending on plasmid copy number. Plasmid DNAs prepared by INSTA-PREP were analyzed and are suitable for use in molecular biology procedures including restriction digestion, ligation with T4 DNA ligase, bacterial transformation, PCR, cultured cell transfection and T7 DNA polymerase or thermostable DNA polymerase-mediated dideoxynucleotide sequencing.

Codominant mixtures of viruses in reference strains of influenza virus due to host cell variation

Influenza viruses grown in chicken eggs may comprise mixtures of variants, creating problems in establishing international reference strains and in preparing high growth reassortants. We therefore analyzed representative reference strains of H3N2 viruses from 1987 to 1989 by direct sequencing of HA1. Three of seven reference strains had different nucleotides at the same position in nucleotide gels, indicating the presence of codominant mixtures. These nucleotide duplications occurred at residues previously shown to code for amino acids associated with egg adaptation (156, 186, and 193 of HA1). Cloning of these viruses in chicken eggs permitted separation of the mixtures, and the majority of these cloned viruses could be distinguished with monoclonal antibodies. The remaining four reference strains were homogeneous and contained one of the two amino acids usually found at these residues in HA1 (e.g., 145 Glu or Lys, 186 Ser or Ile). Analysis of epidemic H3N2 isolates, for which mammalian cell and egg isolates are available for sequence analysis from the same patient, confirmed that multiple nucleotide changes can occur at residues associated with egg adaptation. When reference or epidemic strains containing codominant mixtures were passaged in eggs one to five times, one of the codominant strains usually became dominant. Similar results were obtained with Madin Darby Canine kidney (MDCK) cells, although the dominant virus usually differed from that in eggs. Attempts to reselect an influenza virus possessing sequence changes in HA1 characteristic of mammalian cells or the original human isolate (i.e., 156 Glu, 158 Glu, 186 Ser) by multiple passages in MDCK cells were not successful, but evidence was obtained that MDCK cells can provide a selective growth advantage. Thus, variants that are dominant in eggs are not necessarily dominant in MDCK cells. To preserve the original genotype of viruses used as reference strains, we recommend the following procedure: (i) cloning in chicken eggs of the candidate virus at a very early passage, (ii) selection and analysis of multiple clones with the same ferret polyclonal and/or monoclonal antibodies used in the initial screening, and (iii) selection of the isolate whose hemagglutinin molecule most closely resembles the clinical isolate.

Expectant management of premature rupture of membranes with amniotic fluid cultures positive for Ureaplasma urealyticum alone

OBJECTIVE

Our purpose was to determine maternal and neonatal outcome in patients with premature rupture of membranes and amniotic fluid cultures positive for Ureaplasma urealyticum alone.

STUDY DESIGN

Amniocentesis was performed on 225 patients with premature rupture of membranes at < or = 34 completed weeks of gestation. Amniotic fluid was cultured for aerobic and anaerobic bacteria, Mycoplasma hominis, and Ureaplasma urealyticum. Patients with cultures positive for Ureaplasma urealyticum alone were managed expectantly, including erythromycin and daily biophysical profile examinations.

RESULTS

Thirty-three patients (15%) had amniotic fluid cultures positive for Ureaplasma urealyticum alone, and clinical chorioamnionitis developed in three of these patients. There were no suspected or documented cases of neonatal sepsis. The incidence of infectious morbidity in patients with amniotic fluid cultures positive for Ureaplasma urealyticum alone was not significantly different from that seen in patients with negative cultures.

CONCLUSION

An amniotic fluid culture positive for Ureaplasma urealyticum alone may not be an indication for a preterm delivery in patients with premature rupture of membranes.

Parental well-being and behavioral adjustment of pediatric survivors of burns

Parents of pediatric patients with burns often perceive their children as troubled and having an increased number of problem behaviors. This study examines the relationship between these problem behaviors and the parent's own emotional well-being. Mothers of 38 burned children completed three standardized questionnaires: Child Behavior Checklist, Parental Stress Index, and the Eight State Questionnaire. The population was further divided into troubled and untroubled by a Child Behavior Checklist total problem T score of 60. Parents were not significantly different from reference populations on most of the scales. However, the Parental Stress Index results revealed that parents who report their children as troubled are themselves stressed, not only by their children's behaviors but in areas unrelated to their children. In addition, these mothers report often feeling depressed and guilty on the Eight State Questionnaire. This study emphasizes the need for psychological assessment of both parents and children.

Vasa previa: prenatal diagnosis with transvaginal color Doppler flow imaging

Vasa previa carries a significant risk for fetal exsanguination and death at the time of membrane rupture. The diagnosis is rarely made before the onset of vaginal bleeding. We report the prenatal diagnosis of vasa previa with transvaginal color Doppler flow imaging in an asymptomatic patient with a succenturiate placenta.

Structural rearrangement of infecting Sindbis virions at the cell surface: mapping of newly accessible epitopes

Sindbis virus glycoproteins E1 and E2 undergo a conformational alteration during early virus-cell interaction at the cell surface (D. Flynn, W. J. Meyer, J. M. MacKenzie, Jr., and R. E. Johnston, J. Virol. 64:3643-3653, 1990). Certain epitopes normally internal on native virus become accessible to monoclonal antibody (MAb) binding after attachment but before internalization of virus particles. These newly exposed epitopes, termed transitional epitopes, may be part of functionally important domains made accessible at the surface of the altered virus to facilitate entry into cells. Heating Sindbis virions at 51 degrees C for a short time induced a similar, although not identical, exposition of transitional epitopes on the E1 and E2 glycoproteins (W. J. Meyer, S. Gidwitz, V. K. Ayers, R. J. Schoepp, and R. E. Johnston, J. Virol. 66:3504-3513, 1992). In the current report, we have identified several of the transitional epitopes that become exposed as a consequence of early virus-cell interactions. Transitional epitope MAbs that bound to rearranged, heated virions and virus-cell complexes were used in antibody competition binding assays on heated Sindbis virions to map the spatial relationships between native, external, neutralizing antigenic sites and newly exposed transitional epitopes. Because the heated, rearranged particles retained their infectivity, MAbs that bound to transitional epitopes also were used to isolate MAb neutralization escape mutants. Sequencing the glycoprotein genes of the escape mutants identified specific E1 and E2 loci where mutation prevented MAb binding to transitional epitopes. One of the transitional epitopes identified (E2 residues 200 to 202) lies in the E2 190-216 region, which harbors two major neutralization sites, E2a and E2b, and an N-linked glycosylation site at E2 196. The glycosylation signal was eliminated by site-directed mutagenesis of a full-length cDNA clone of the Sindbis virus genome. The absence of a carbohydrate moiety did not expose the transitional epitopes mapped to this locus, suggesting that on native virions, the inaccessibility of the E2 200-202 determinant was inherent in the structure of the glycoprotein spike.

Influence of host cell-mediated variation on the international surveillance of influenza A (H3N2) viruses

Growth of clinical specimens of influenza viruses in eggs can result in the selection of antigenic variants distinct from corresponding viruses grown in mammalian tissue culture. To evaluate the contribution of host cell selection on the antigenic diversity of human influenza isolates, as seen in annual surveillance studies, viruses grown in embryonated eggs were compared by antigenic and genetic analyses with their mammalian tissue culture-grown counterparts. Clinical specimens were gathered from around the world from late 1987 to 1990 and the antigenicity of isolated viruses was assessed by hemagglutination-inhibition assays using immune ferret sera as is currently performed for routine surveillance and the selection of vaccine strains. In addition, viruses were assessed using a panel of anti-H3 HA monoclonal antibodies. The extent of antigenic variation exhibited by the egg-grown strains was far greater than the relative antigenic homogeneity of the tissue culture-grown viruses. Nucleotide sequence analysis of HA1 gene PCR products of 28 MDCK cell and egg derived pairs allowed identification of amino acid substitutions responsible for the antigenic differences observed and the adaptation to growth in eggs. Among these substitutions was a change at amino acid position 186 of HA1 (Ser in tissue culture viruses and lle in egg-grown viruses) which was observed at relatively high frequency. Egg- and MDCK-grown pairs with this single amino acid difference were classified into distinct antigenic groups by ferret sera raised to WHO reference viruses. Given the additional antigenic diversity observed among egg-grown strains, considerable care should be taken in the selection of reference and vaccine strains grown in eggs. Rapid sequence comparisons of MDCK- and egg-grown viruses allow identification of variants arising through egg selection and will prove to be a useful adjunct to antigenic surveillance for the selection of reference and vaccine strains.

The fetal transverse cerebellar diameter/abdominal circumference ratio: a gestational age-independent method of assessing fetal size

The relationship between the fetal TCD and the AC throughout pregnancy was investigated in a prospective, cross-sectional study of 700 well dated, normal pregnancies between 14 and 42 weeks of gestation and tested in 30 known SGA infants. Fetal measurements included the TCD, AC, BPD, HC, and FL. The TCD/AC ratio was calculated for each patient. Statistical analysis using linear regression and Student's t-test was performed. Strong correlation existed between gestational age and transcerebellar diameter (R2 = 0.9464), between gestational age and AC (R2 = 0.9685), and between TCD and AC (R2 = 0.9561). The TCD/AC ratio was normally distributed with a mean +/- SD of 13.69 +/- 0.94% (median, 13.71%). The 10th and 90th percentiles were 12.50% and 14.86%, respectively. The ratio remained constant throughout pregnancy with respect to gestational age (R2 = 0.0084). A TCD/AC ratio greater than the 90th percentile was present in 87% (26/30) known SGA infants. The TCD/AC ratio is a stable, gestational age-independent parameter that may be useful in the early detection of fetal growth abnormalities.

Ultrasonographic prenatal diagnosis of the 13q-syndrome

A case is presented in which ultrasonographic examination led to the prenatal detection of a ring 13 chromosome in a fetus. At 18 weeks' gestation, the fetus presented with holoprosencephaly, an abnormal configuration of the lower extremities, and an atrial septal defect. Although the amount of amniotic fluid was normal, limb movements were never observed throughout pregnancy. The lower extremities were always flexed at the knee and talipes equinovarus was present. Hydrocephaly became apparent during the 2nd trimester. The ultrasonographic findings were confirmed by postpartum autopsy and X-ray examination. The ring chromosome was identified through amniocentesis and later verified in postpartum tissue.

Inhibitory effects of ascorbic acid on growth of leukemic and lymphoma cell lines

Vitamin C has been suggested and disputed as an anti-cancer agent. Previous in vitro studies using either primary cell cultures from cancer patients or tumor cell lines have suggested that tumor cells with different lineages may have different sensitivities to ascorbic acid. In this study we report characterization of the effects of ascorbic acid on growth of two ascorbic acid sensitive and one ascorbic acid resistant lymphocyte tumor cell lines. The cytotoxic effects of ascorbic acid on the sensitive cell lines were time and dosage dependent. Furthermore, the energy state of the ascorbic acid sensitive cells was affected by the presence of ascorbic acid before the cells became apparently non-viable, as demonstrated by 31P nuclear magnetic resonance spectroscopy. The existence of these lymphocyte cell lines with varying sensitivities to ascorbic acid may provide a useful model system for further understanding of vitamin C action on cancer cells.

Use of recombinant human erythropoietin in a Jehovah's Witness

We report the case of a Jehovah's Witness who bled massively, refused blood transfusion, and survived profound anemia (hematocrit = 5.6%) intact. The patient was treated with recombinant human erythropoietin, parenteral iron, and oxygen. The pharmacology and hematopoietic response to erythropoietin are discussed. We suggest considering this therapy for acutely anemic patients who refuse transfusion to decrease the duration of the most severe anemia.

The role of a research seminar for child psychiatry residents

A major problem confronting the field of child and adolescent psychiatry is the development of teaching strategies to stimulate research activities and an appreciation of research. A teaching approach is described which emphasizes major research concepts using a programmed instruction method and illustrating these concepts with clinical cases. Fourteen child psychiatry residents participated in the seminar during a 3-year period. Overall, trainees' evaluation of the seminar was positive, and they demonstrated a high level of understanding across major research topics. In addition, the seminar may have contributed to an increased preference for academic careers by graduating residents.

Effect of time and storage temperature on amniotic fluid glucose concentration

OBJECTIVE

To evaluate the effects of time and storage temperature on amniotic fluid (AF) glucose concentration.

METHODS

Amniocentesis was performed on 47 patients with preterm labor or preterm rupture of membranes at or before 34 weeks' estimated gestation and the AF was cultured for aerobic, anaerobic, Mycoplasma, and Ureaplasma organisms. Twenty-one samples were stored at 37C, 13 were kept at room temperature (22C), and 13 were frozen (-20C). Glucose concentration was measured at 0 and 12 hours on all AF samples and at 2, 4, and 6 hours on the unfrozen samples.

RESULTS

No significant change in AF glucose concentration occurred over time at any storage temperature in the 35 samples with negative cultures. In 12 AF samples with positive cultures, a significant decrease from baseline was noted at 2 and 4 hours in those kept at 37C and 22C (P = .016). Glucose concentration was unchanged in frozen samples regardless of the culture results. The initial AF glucose concentration was significantly lower in samples with positive than in those with negative cultures (P < .0001).

CONCLUSION

Amniotic fluid glucose concentration does not change over 12 hours in the absence of intra-amniotic infection.

Immunoreactive growth hormone production by human lymphocyte cell lines

1. Two human lymphocyte cell lines, a T-cell line and a B-cell line, were shown to produce and secrete immunoreactive growth hormone (irGH). The irGH molecules secreted by the two cell lines appeared to be de novo synthesized and their molecular size was similar to that of pituitary GH as well as irGH secreted by peripheral blood lymphocytes. 2. Affinity-purified irGH molecules had human growth hormone (hGH)-like mitogenic activity on Nb2 cells. These findings indicate that the irGH molecules produced by H9 and IM9 were similar to hGH in structure. 3. However, the irGH messages could not be amplified by polymerase chain reaction (PCR) primers which had been demonstrated to be able to amplify reverse-transcribed hGH messenger RNA successfully, suggesting that the lymphocyte-derived irGH and pituitary hGH are not exactly identical molecules. 4. We conclude that the H9 and IM9 cells produce a growth hormone-related molecule whose structure is different from that in the anterior pituitary.

Comparison of gram stain, leukocyte esterase activity, and amniotic fluid glucose concentration in predicting amniotic fluid culture results in preterm premature rupture of membranes

OBJECTIVE

The purpose of this study was to prospectively compare three rapid and inexpensive tests that have been proposed as predictors of amniotic fluid culture results in preterm premature rupture of membranes.

STUDY DESIGN

Amniocentesis was performed on 117 patients < or = 34 weeks' gestational age with premature rupture of membranes and no clinical evidence of infection. Amniotic fluid was sent for Gram stain and aerobic, anaerobic, and Mycoplasma cultures. Leukocyte esterase activity and glucose concentration were also determined on the amniotic fluid.

RESULTS

Amniotic fluid cultures were positive in 56 patients (47.8%). Leukocyte esterase activity of 1+ or 2+ and an amniotic fluid glucose concentration < or = 16 mg/dl were significantly more sensitive (p < 0.005) than Gram stain in detecting positive amniotic fluid cultures (73%, 68%, and 41%, respectively).

CONCLUSIONS

Although each of these rapid tests is useful in assessing for subclinical intraamniotic infection, none of them have sufficient accuracy to make clinical decisions solely on the basis of their results.

Biophysical profile as a predictor of amniotic fluid culture results

The biophysical profile has been proposed as a noninvasive method of detecting fetal infection in patients with preterm premature rupture of membranes (PROM). The purpose of this study was to evaluate the biophysical profile as a rapid predictor of amniotic fluid (AF) culture results in women with PROM. Amniocentesis was performed on 111 patients with PROM at or before 34 weeks' estimated gestational age. Aerobic, anaerobic, Ureaplasma, and Mycoplasma cultures were performed on the AF. A biophysical profile was performed just before the amniocentesis. Women with positive AF cultures had a significantly lower total biophysical profile score, as well as significantly lower scores for nonstress test, fetal breathing movements, fetal movements, and AF volume, than those with negative AF cultures. However, neither the total biophysical profile score nor any of the individual components had sufficient sensitivity, specificity, or positive or negative predictive value to be useful clinically in predicting culture results. Although the incidence of positive AF cultures was inversely related to the biophysical profile score, 48% of patients with a score of 8 and 27% of those with a score of 10 had positive AF cultures. The results of this study do not support use of the biophysical profile as an early predictor of AF culture results in patients with PROM.

Conformational alteration of Sindbis virion glycoproteins induced by heat, reducing agents, or low pH

Sindbis virions undergo a conformational rearrangement after attachment to cells but prior to entry, as detected by exposure of epitopes on virus-cell complexes which are not accessible to their cognate monoclonal antibodies on native virions (D. C. Flynn, W. J. Meyer, and R. E. Johnston, J. Virol. 64:3643-3653, 1990). The rearrangement did not appear to require transit of virions through a low-pH environment, and the altered virions participated in a productive infection. This naturally occurring structural alteration could be mimicked, although not precisely duplicated, by any of the three artificial treatments of purified virions in vitro: brief incubation at 51 degrees C, treatment with 1 to 5 mM dithiothreitol, or incubation of pH 5.8 to 6.0. Infectivity was maintained after all three treatments, suggesting that Sindbis virions are metastable and can exist in at least two infectious conformations. The integrity of external, neutralizing epitopes was maintained on cell-associated virions and in the altered conformations induced by heat and dithiothreitol, whereas these epitopes were unreactive under low-pH conditions that induced an analogous exposure of previously inaccessible epitopes. The pH at which the conformational change was induced and the pH at which virions could mediate cell-cell fusion from without were coordinately shifted when these two parameters were determined for another strain of Sindbis virus. This coordinate shift in pH optima suggests that the conformational change in virion structure observed at the cell surface may be causally related to fusion.