Myosin light chain kinase and myosin light chain phosphatase from Dictyostelium: effects of reversible phosphorylation on myosin structure and function.

We have partially purified myosin light chain kinase (MLCK) and myosin light chain phosphatase (MLCP) from Dictyostelium discoideum. MLCK was purified 4,700-fold with a yield of approximately 1 mg from 350 g of cells. The enzyme is very acidic as suggested by its tight binding to DEAE. Dictyostelium MLCK has an apparent native molecular mass on HPLC G3000SW of approximately 30,000 D. Mg2+ is required for enzyme activity. Ca2+ inhibits activity and this inhibition is not relieved by calmodulin. cAMP or cGMP have no effect on enzyme activity. Dictyostelium MLCK is very specific for the 18,000-D light chain of Dictyostelium myosin and does not phosphorylate the light chain of several other myosins tested. Myosin purified from log-phase amebas of Dictyostelium has approximately 0.3 mol Pi/mol 18,000-D light chain as assayed by glycerol-urea gel electrophoresis. Dictyostelium MLCK can phosphorylate this myosin to a stoichiometry approaching 1 mol Pi/mol 18,000-D light chain. MLCP, which was partially purified, selectively removes phosphate from the 18,000-D light chain but not from the heavy chain of Dictyostelium myosin. Phosphatase-treated Dictyostelium myosin has less than or equal to 0.01 mol Pi/mol 18,000-D light chain. Phosphatase-treated myosin could be rephosphorylated to greater than or equal to 0.96 mol Pi/mol 18,000-D light chain by incubation with MLCK and ATP. We found myosin thick filament assembly to be independent of the extent of 18,000-D light-chain phosphorylation when measured as a function of ionic strength. However, actin-activated Mg2+-ATPase activity of Dictyostelium myosin was found to be directly related to the extent of phosphorylation of the 18,000-D light chain. MLCK-treated myosin moved in an in vitro motility assay (Sheetz, M. P., and J. A. Spudich, 1983, Nature (Lond.), 305:31-35) at approximately 1.4 micron/s whereas phosphatase-treated myosin moved only slowly or not at all. The effects of phosphatase treatment on the movement were fully reversed by subsequent treatment with MLCK.

Computer Decision Support Changes Physician Practice But Not Knowledge Regarding Autism Spectrum Disorders.

OBJECTIVE: To examine whether adding an autism module promoting adherence to clinical guidelines to an existing computer decision support system (CDSS) changed physician knowledge and self-reported clinical practice. METHODS: The CHICA (Child Health Improvement through Computer Automation) system, a CDSS, was enhanced with a module to improve management of autism in 2 of the 4 community pediatric clinics using the system. We examined the knowledge and beliefs of pediatric users using cross-sectional surveys administered at 3 time points (baseline, 12 months and 24 months post-implementation) between November 2010 and January 2013. Surveys measured knowledge, beliefs and self-reported practice patterns related to autism. RESULTS: A total of 45, 39, and 42 pediatricians responded at each time point, respectively, a 95-100% response rate. Respondents' knowledge of autism and perception of role for diagnosis did not vary between control and intervention groups either at baseline or any of the two post-intervention time points. At baseline, there was no difference between these groups in rates in the routine use of parent-rated screening instruments for autism. However, by 12 and 24 months post-implementation there was a significant difference between intervention and control clinics in terms of the intervention clinics consistently screening eligible patients with a validated autism tool. Physicians at all clinics reported ongoing challenges to community resources for further work-up and treatment related to autism. CONCLUSIONS: A CDSS module to improve primary care management of ASD in pediatric practice led to significant improvements in physician-reported use of validated screening tools to screen for ASDs. However it did not lead to corresponding changes in physician knowledge or attitudes.

Leveraging electronic tablets for general pediatric care: a pilot study.

BACKGROUND: We have previously shown that a scan-able paper based interface linked to a computerized clinical decision support system (CDSS) can effectively screen patients in pediatric waiting rooms and support the physician using evidence based care guidelines at the time of clinical encounter. However, the use of scan-able paper based interface has many inherent limitations including lacking real time communication with the CDSS and being prone to human and system errors. An electronic tablet based user interface can not only overcome these limitations, but may also support advanced functionality for clinical and research use. However, use of such devices for pediatric care is not well studied in clinical settings. OBJECTIVE: In this pilot study, we enhance our pediatric CDSS with an electronic tablet based user interface and evaluate it for usability as well as for changes in patient questionnaire completion rates. METHODS: Child Health Improvement through Computers Leveraging Electronic Tablets or CHICLET is an electronic tablet based user interface. It is developed to augment the existing scan-able paper interface to our CDSS. For the purposes of this study, we deployed CHICLET in one outpatient pediatric clinic. Usability factors for CHICLET were evaluated via caregiver and staff surveys. RESULTS: When compared to the scan-able paper based interface, we observed an 18% increase or 30% relative increase in question completion rates using CHICLET. This difference was statistically significant. Caregivers and staff survey results were positive for using CHICLET in clinical environment. CONCLUSIONS: Electronic tablets are a viable interface for capturing patient self-report in pediatric waiting rooms. We further hypothesize that the use of electronic tablet based interfaces will drive advances in computerized clinical decision support and create opportunities for patient engagement.

Cyclic adenosine monophosphate and ovarian follicular fluid act synergistically to inhibit mouse oocyte maturation.

The relationship between cAMP and the capacity of two partially-purified fractions of porcine follicular fluid (PFF) to suppress mouse oocyte maturation was investigated. The fractions used were: 1) a low molecular weight filtrate (less than 10,000) derived from Amicon PM10 filtration of PFF (PM10), and 2) a fraction from Bio-Gel P2 chromatography of the PM10 filtrate (Bio-Gel) that has meiotic inhibitory activity in porcine oocytes. PM10 alone produced a transient inhibition of the maturation of both cumulus cell-enclosed and denuded mouse oocytes, as manifested by germinal vesicle breakdown. The addition of FSH or (Bu)2cAMP to medium containing either of the PFF fractions resulted in dramatic synergism of the inhibitory effect of PFF alone in cumulus cell-enclosed oocytes. Forskolin or (Bu)2cAMP promoted a similar synergistic response with either PFF fraction in denuded oocytes. The degree of inhibition was consistently greater in cumulus cell-enclosed than in denuded oocytes. The putative inhibitor was dialyzable through tubing having a nominal molecular weight cutoff of 1,000. Proteolysis, acid hydrolysis, or ether extraction of PM10 did not reduce its inhibitory synergism with (Bu)2cAMP. However, inhibition was completely abolished by charcoal extraction. Steroid hormones did not mimic the PM10-induced synergism when added to (Bu)2cAMP-containing medium in a concentration at least 14-fold greater than that present in PM10-supplemented medium. In conclusion, our results demonstrate the presence of a factor(s) in PFF that acts synergistically with a cAMP-dependent process to inhibit oocyte maturation in vitro. Furthermore, although PFF fractions suppressed the maturation of both denuded and cumulus cell-enclosed oocytes, cumulus cells appear to mediate the inhibitory activity of PFF. The data also suggest that the PFF inhibitor is a small (mol wt less than 1,000) hydrophobic molecule but not a peptide or nonpolar lipid.

A systematic review of vision screening tests for the detection of amblyopia.

OBJECTIVE: To review the test characteristics and the quality of evidence regarding available screening tests for the detection of amblyopia in preschool-aged children to help primary care practitioners select a screening strategy. DESIGN: Systematic review of published studies. DATA SOURCES: The MEDLINE database was searched from 1966 through January 1999 using a broad and inclusive strategy. A total of 9551 citations were identified. STUDY SELECTION: All studies that compared the results of commercially available screening tests in preschool-aged children to ophthalmologic examination. DATA EXTRACTION: The setting of the study, the age of the population, the type of screening test, criteria for a positive screen, criteria for the ophthalmologic examination, test characteristics, and measures of reliability were abstracted by 2 reviewers for each selected study. DATA SYNTHESIS: Four eligible articles were identified that studied the test characteristics of 3 screening tests. None of these studies were performed in a primary care setting. Each study used different criteria for failure of the ophthalmologic examination. None of the studies measured observer or test reliability. CONCLUSIONS: Few high-quality data exist regarding the performance of preschool vision screening. Important future work should include the development of a consensus gold standard ophthalmologic examination and evaluation of screening tests in the primary care setting.

Hospital-acquired urinary tract infections in the pediatric patient: a prospective study.

To determine through a prospective study the characteristics of hospital-acquired urinary tract infections (HAUTI) in children, 525 children subjected to bladder catheterization during a hospital admission were identified through surveillance of 12,316 admissions during a 24-month period. Urine culture results were available for 296 (56.4%) of the catheterized patients. In addition 12 noncatheterized children with a documented HAUTI were identified. The clinical courses of all patients with a HAUTI were followed for at least 6 months after their last HAUTI during the study period. Forty-four patients, 1 week to 17 years of age, with 1 or more HAUTI during a hospital unit admission were identified. A total of 51 HAUTI occurred. Thirty-nine (76.5%) of the infections occurred in patients subjected to catheterization. Thirty-two (10.8%) of 296 catheterized patients developed a HAUTI. Forty-three (84.3%) of the 51 infections were single organism infections. One HAUTI was associated with a wound infection with the same organism and one with a concurrent bacteremia with the same organism. Relapses were seen after 4 HAUTI. One reinfection was identified. There were no deaths directly associated with a HAUTI. Hospitalized children subjected to urinary tract catheterization are at significant risk for HAUTI. Complications are infrequent and not life-threatening.

A cost-effectiveness analysis of newborn hearing screening strategies.

CONTEXT: Congenital hearing loss affects between 1 and 3 out of every 1,000 children. Screening of all neonates has been made possible by the development of portable automated devices. Universal screening is a 2-stage screening process using automated transient-evoked otoacoustic emissions, followed when indicated by automated auditory brain response testing. Targeted screening reserves the 2-stage screening process for those infants at risk for congenital hearing loss. OBJECTIVE: To compare the expected costs and benefits of targeted screening with universal screening for the detection of significant bilateral congenital hearing loss. DESIGN: Cost-effectiveness analysis from the health care system perspective. including costs directly related to screening and initial follow-up evaluation. MAIN OUTCOME MEASURES: Number of cases identified, number of false positives, and cost per case. RESULTS: For every 100,000 newborns screened, universal screening detects 86 of 110 cases of congenital hearing loss, at a cost of $11,650 per case identified. Targeted screening identifies 51 of 110 cases, at $3,120 per case identified. Universal screening produces 320 false-positive results, 304 more than targeted screening. Switching to universal screening from targeted screening would cost an additional $23, 930 for each extra case detected. CONCLUSIONS: Universal screening detects more cases of congenital hearing loss, at the expense of both greater cost and more false-positive screening results. Little is known about the negative impact of false-positive screening and about the benefits of early intervention for congenital hearing loss. Those who advocate adoption of universal screening should be aware not only of the direct costs of universal screening, but of the indirect costs and strategies to increase the benefits of screening.

Clinical preventive services efficacy and adolescents' risky behaviors.

OBJECTIVE/BACKGROUND: To analyze the value of studying or implementing office-based clinical preventive services for adolescents. Most adolescent mortality and morbidity is attributable to risky behaviors, yet clinical preventive services to reduce risky behaviors are often challenged because their efficacy has not been demonstrated. DESIGN: A cost-effectiveness model of adolescents' risky behaviors that compares standard practice with a program of screening visits for all adolescents and counseling visits for youth identified as high risk. We considered two risky behaviors, alcohol abuse and unsafe sexual activity, and five outcomes. MAIN OUTCOME MEASURES: Baseline cost-effectiveness of the program, minimum efficacy at which the program would be cost-effective, and sample sizes required for a trial of the program. RESULTS: Assuming that the program is 5% effective at preventing risky behaviors, it would cost $3035 to prevent any one adverse outcome and $471,000 to prevent a death from an automobile crash or from human immunodeficiency virus infection. Assuming society were willing to pay $600,000 to prevent a death (a generally accepted figure), the program would be cost-effective only if it were 5.6% effective at changing behavior. At this efficacy, the program would have a cost per year of life saved comparable to or better than many other accepted medical interventions. However, to demonstrate changes in outcomes at this efficacy would require a clinical trial with between 4000 and 95 million adolescents in each treatment group, depending on the outcome measured. CONCLUSIONS: Studying the ability of clinical preventive services to prevent outcomes of adolescents' risky behaviors would be impractical. The decision to implement these programs should be made based on current knowledge and beliefs; their efficacy can probably be studied only as part of widespread implementation.

Cost-effectiveness analysis of lead poisoning screening strategies following the 1997 guidelines of the Centers for Disease Control and Prevention.

OBJECTIVE: To compare blood lead (BPb) poisoning screening strategies in light of the 1997 recommendations by the Centers for Disease Control and Prevention, Atlanta, Ga. DESIGN: Cost-effectiveness analysis from the perspective of the health care system to compare the following 4 screening strategies: (1) universal screening of venous BPb levels; (2) universal screening of capillary BPb levels; (3) targeted screening of venous BPb levels for those at risk; and (4) targeted screening of capillary BPb levels for those at risk. Costs of follow-up testing and treatment were included in the model. RESULTS: Only universal venous screening detected all BPb levels of at least 0.48 micromol/L (10 microg/dL). Universal capillary screening detected between 93.2% and 95.5% of cases, depending on the prevalence of elevated BPb levels. Targeted screening was the least sensitive strategy for detecting cases. Venous testing identified between 77.3% and 77.9% of cases, and capillary testing detected between 72.7% and 72.8% of cases. In high-prevalence populations, universal venous screening minimized the cost per case ($490). In low- and medium-prevalence populations, targeted screening using venous testing minimized the cost per case ($729 and $556, respectively). In all populations, regardless of screening strategy, venous testing resulted in a lower cost per case than capillary testing. Sensitivity analyses of all parameters in this model demonstrated that this conclusion is robust. CONCLUSIONS: Universal screening detects all cases of lead poisoning and is the most cost-effective strategy in high-prevalence populations. In populations with lower prevalence, the cost per case detected using targeted screening is less than that of universal screening. The benefit of detecting a greater number of cases using universal screening must be weighed against the extra cost of screening. Regardless of whether a strategy of universal or targeted screening is used, the cost per case using venous testing is less than that of capillary testing.

Parents' utilities for outcomes of occult bacteremia.

OBJECTIVE: To describe parents' values for outcomes of occult bacteremia using utility assessment, a quantitative method that incorporates risk preference. DESIGN: Computer-based utility assessment interview. SETTING: Urban children's hospital pediatric emergency department with 50 000 visits annually. PARTICIPANTS: Convenience sample of parents presenting with a child between 3 and 36 months. MAIN OUTCOME MEASURE: Parents' utility values for 8 outcomes from treatment of occult bacteremia: blood drawing, localized infection, hospitalization for antibiotics, meningitis with recovery, meningitis resulting in deafness, minor brain damage, severe brain damage, and death. RESULTS: Ninety-four subjects successfully completed the interview. Mean utilities were 0.9974 for blood drawing, 0.9941 for local infection, 0.9921 for hospitalization, 0.9768 for meningitis with recovery, 0.8611 for deafness, 0.7393 for minor brain damage, 0.3903 for severe brain damage, and 0.0177 for death. All values were significantly different from those that immediately preceded and succeeded (P<.0001), except for local infection vs hospitalization (P = .14). Median utilities for blood drawn, local infection, and hospitalization were 1. There were no significant differences among utilities of parents who presented with a febrile child (temperature > or =39 degrees C), or an afebrile child (temperature <39 degrees C). There were also no significant differences among utilities regardless of whether parents had children with prior experience with the outcomes. CONCLUSIONS: Assessment of utilities for outcomes of occult bacteremia yielded extremely high mean and median values for outcomes without permanent sequelae. This suggests that parents presenting to an emergency department may rationally prefer painful transient experiences, including venipuncture, for their children rather than risk even rare chances of severe outcomes.

Pediatric injury prevention counseling: an observational study of process and content.

OBJECTIVES: To describe routine injury prevention counseling; to observe how three visit components - printed prompts, parent remarks, and parent behaviors - affect such counseling; to describe the process and content of discussions about car seats as an example of routine injury prevention. METHODS: A total of 128 well-child visits of children under 7 months of age to a university pediatric clinic were videotaped (76% of eligible visits). RESULTS: Three injury topics were mentioned, on an average, per visit. Parents or caregivers rarely introduced injury topics (5%). Physicians frequently introduced those topics listed on age-specific prompting sheets (73%). Car seat counseling typically began with a physician's question (82%). Most asked simply about ownership or use (93%). Few addressed difficult issues, such as consistency of use (11%). CONCLUSIONS: Physicians bring up the injury topics that are prompted. However, most discussion is superficial. Printed prompts that address counseling process as well as content might be beneficial.

The role of purines in the maintenance of meiotic arrest in mouse oocytes.

Meiotic arrest of mammalian oocytes within ovarian follicles is maintained by a specific factor(s) within the follicle. There is strong evidence that cAMP plays an important role in the control of meiosis. Purines have also been implicated in the maintenance of meiotic arrest in vivo. Hypoxanthine and/or adenosine have been identified in pig and mouse follicular fluid and exert a meiosis-arresting action on mouse oocytes in culture. While adenosine apparently need not be metabolized to exert its action on oocyte maturation, the action of hypoxanthine is apparently due to the production of guanyl and/or xanthyl compounds by the oocyte-cumulus cell complex. The inosine monophosphate dehydrogenase inhibitors, mycophenolic acid and bredinin, induced maturation in cumulus cell-enclosed oocytes maintained in meiotic arrest by hypoxanthine. Hypoxanthine and adenosine are not toxic to oocytes, because oocytes undergo normal fertilization and pre- and post-implantation development following exposure to these molecules in vitro. It is not known how gonadotropins stimulate the resumption of meiosis within the follicle, but there are several possibilities: (1) the intrafollicular level of an oocyte maturation inhibitor is decreased; (2) the oocyte is uncoupled from surrounding follicle cells; (3) an inhibitory molecule is secreted or metabolized by the oocyte; and/or (4) a positive stimulus is produced by the follicle that overrides the presence of inhibitory molecules. Preliminary evidence suggests that cumulus cells may produce a positive stimulus that induces the maturation of cultured cumulus cell-enclosed oocytes. Whether germinal vesicle breakdown in vivo results from a positive induction, a loss of inhibitory input, or a combination of these two mechanisms remains to be determined.

Actionable recommendations in the Bright Futures child health supervision guidelines.

BACKGROUND: With the growing use of electronic health record systems, there is a demand for an electronic version of the leading American pediatric preventive care guideline, Bright Futures. As computer implementation requires actionable recommendations, it is important to assess to what degree Bright Futures meets criteria for actionability. OBJECTIVES: We aimed to 1) determine the number of actionable recommendations in the current edition of Bright Futures and 2) to recommend a specific format for representing an important class of guidelines in a way that better facilitates computer implementation. METHODS: We consolidated all action statements in Bright Futures into recommendations. We then used two dimensions (decidability and executability) in the Guideline Implementability Appraisal v 2.0 (GLIA) to determine the actionability of the recommendations. Decidability means the recommendation states precisely under what conditions to perform those actions. Executability means actions are stated specifically, unambiguously and in sufficient detail. The results were presented in a figure titled Service Interval Diagram (SID), describing actionable recommendations, age intervals during which they are applicable, and how frequently they should occur in that interval. RESULTS: We consolidated 2161 action items into 245 recommendations and identified 52 that were actionable (21%). Almost exclusively, these recommendations addressed screening, such as newborn metabolic screening, or child safety, such as car seat use. A limited number (n=13) of recommendations for other areas of anticipatory guidance were also actionable. No recommendations on child discipline, family function or mental health met our criteria for actionability. The SID representing these recommendations is presented in a figure. CONCLUSION: Only a portion of the Bright Futures Guidelines meets criteria for actionability. Substantial work lies ahead to develop most recommendations for anticipatory guidance into a computer implementable format.

Gender differences in risk attitudes.

PURPOSE: A rich literature has documented gender-based differences in health care utilization and outcomes. The role of risk attitude in explaining the variations is limited at best. This study examines gender differences in health utilities and risk attitudes. METHODOLOGY: Data on 13 health states were collected from 629 students via questionnaires at the Ben-Gurion University of the Negev in 2005. From each respondent, we assessed utilities for a subset of health states, using Time Trade-Off and Standard Gamble. A risk attitude coefficient was calculated for each respondent as a function of their utilities for all outcomes assessed. The risk coefficient derived from a closed-form utility model for men was compared to that of women using the t-statistic. FINDINGS: There was a statistically significant difference in the risk attitudes of men and women. Men had a concave utility function, representing risk aversion, while women had a near linear utility function, suggesting that women are risk neutral. PRACTICAL/SOCIAL IMPLICATIONS: Differences in risk attitude may be an important contributor to gender-based disparities in health services utilization. More research is needed to assess its full impact on decision-making in health care.

Understanding why clinicians answer or ignore clinical decision support prompts.

INTRODUCTION: The identification of key factors influencing responses to prompts and reminders within a computer decision support system (CDSS) has not been widely studied. The aim of this study was to evaluate why clinicians routinely answer certain prompts while others are ignored. METHODS: We utilized data collected from a CDSS developed by our research group--the Child Health Improvement through Computer Automation (CHICA) system. The main outcome of interest was whether a clinician responded to a prompt. RESULTS: This study found that, as expected, some clinics and physicians were more likely to address prompts than others. However, we also found clinicians are more likely to address prompts for younger patients and when the prompts address more serious issues. The most striking finding was that the position of a prompt was a significant predictor of the likelihood of the prompt being addressed, even after controlling for other factors. Prompts at the top of the page were significantly more likely to be answered than the ones on the bottom. CONCLUSIONS: This study detailed a number of factors that are associated with physicians following clinical decision support prompts. This information could be instrumental in designing better interventions and more successful clinical decision support systems in the future.

Purine control of mouse oocyte maturation: evidence that nonmetabolized hypoxanthine maintains meiotic arrest.

Hypoxanthine is present in preparations of follicular fluid and has been shown to suppress the spontaneous meiotic maturation of mammalian oocytes in vitro. The present experiments examined the possible role of hypoxanthine metabolism in mediating this meiotic arrest. Four putative inhibitors of the enzyme, hypoxanthine phosphoribosyltransferase (HPRT), which metabolizes hypoxanthine to inosine monophosphate, were tested on lysates of oocyte-cumulus cell complexes. At a concentration of 1 mM, 6-mercapto-9-(tetrahydro-2-furyl)-purine (MPTF) and 6-mercaptopurine (6-MP) suppressed enzymatic activity by 86% and 98%, respectively, while 6-azauridine and 2,6-bis-(hydroxyamino)-9-beta-D-ribofuranosyl-purine had no effect. MPTF and 6-MP increased the inhibitory effect of hypoxanthine on germinal vesicle breakdown, but the other agents did not. The 2 active agents had similar effects on salvage activity and hypoxanthine-maintained meiotic arrest in denuded oocytes. Also, oocytes from XO mice were more sensitive to the meiosis-arresting action of hypoxanthine than oocytes from XX littermates, which have twice the HPRT activity. The actions of the HPRT inhibitors were not due to their conversion to nucleotides via HPRT and negative feedback on purine de novo synthesis, because azaserine and 6-methylmercaptopurine riboside, which are more potent inhibitors of de novo synthesis, had a stimulatory, rather than inhibitory, effect on hypoxanthine-arrested oocytes. Furthermore, several lines of evidence indicate that metabolism of hypoxanthine to xanthine and uric acid by xanthine oxidase does not mediate the inhibitory action of this purine base on meiotic maturation. The data therefore suggest that nonmetabolized hypoxanthine is responsible for the meiotic arrest observed, most likely through suppression of cAMP degradation.

Adenosine blocks hormone-induced meiotic maturation by suppressing purine de novo synthesis.

We have examined adenosine (Ado) suppression of FSH-induced germinal vesicle breakdown (GVB) and its relationship to purine de novo synthesis. Oocyte-cumulus cell complexes (OCC) from PMSG-primed, immature mice were cultured 17-18 hr in medium containing 4 mM hypoxanthine (HX) or 300 microM dibutyryl cAMP (dbcAMP) to maintain meiotic arrest, and FSH was added to stimulate meiotic maturation. In the absence of FSH, Ado (1-250 microM) had no effect in dbcAMP-arrested oocytes but dose-dependently suppressed maturation in HX-treated oocytes. FSH-induced maturation was prevented by Ado, though more effectively in dbcAMP-supplemented cultures. Ado affected the magnitude, but not the kinetics pattern, of the response to FSH. Inosine also blocked meiotic induction, but only in dbcAMP-arrested oocytes. Purine de novo synthesis was nearly doubled in OCC by FSH treatment, and this response was completely prevented by Ado. FSH had no effect on HX salvage, although Ado reduced this activity by 98%. Inosine effects on metabolism were intermediate between the control and Ado groups. Experiments with radiolabeled energy substrates showed that Ado suppressed FSH activation of the pentose phosphate pathway but did not prevent significant activation of glycolysis or oxidation of pyruvate. Finally, in cultured follicles from primed mice, hCG-induced maturation was blocked by Ado as effectively as by the purine de novo synthesis inhibitor, azaserine. It is concluded that Ado has an inhibitory action on hormone-induced maturation that is due, at least in part, to suppression of glucose metabolism, leading to compromised purine de novo synthesis.