Learning with digital recording and video review of delivery room resuscitation.

Digital recording and video review of delivery room resuscitations is a proven useful tool to evaluate neonatal resuscitation program (NRP) technical and non-technical skills. It is also valuable for research, quality improvement, and individual and group learning. Digital recording and video review programs are growing in number, and planning and implementation of digital recording requires careful thought. Consideration of technology requirements, policy implementation, and stakeholder involvement is essential to implement a successful digital recording and video review program. Video review can then be applied for individual and team-based learning. An approach to sustainability and on-going quality review of the program are key components critical to success.

Teamwork, communication and resident leadership at resident-attended, neonatal delivery room resuscitations.

OBJECTIVE: Determine if a NICU resident delivery room (DR) skills educational curriculum is associated with changes in neonatal resuscitation team characteristics, including teamwork, communication and leadership. STUDY DESIGN: This prospective, observational study of resident-attended neonatal resuscitations utilized team questionnaire, video assessment and chart review. Each resident NICU block included a curriculum consisting of two educational programs focusing on NRP knowledge and skills with additional emphasis on teamwork and communication strategies. RESULTS: Ninety-nine resuscitations met inclusion criteria. Comparing behaviors at the beginning versus end of a NICU block, residents demonstrated increased frequency of initiating leadership (31% vs. 93%, p < 0.001) and maintaining leadership (19% vs. 79%, p < 0.001) at low-risk, resident-attended DR resuscitations. Overall measurements of teamwork and communication were unchanged. CONCLUSIONS: A NICU DR skills educational curriculum is associated with increased resident leadership at low-risk DR resuscitations over the course of NICU blocks, without compromising measurements of teamwork or communication.

Risk factors associated with prolonged neonatal intensive care unit stay after threatened late preterm birth.

OBJECTIVE: To identify risk factors associated with neonatal intermediate or intensive care unit (NICU) stay ≥3 days among women with threatened late preterm birth (PTB). STUDY DESIGN: Secondary analysis of women with nonanomalous, singleton gestations enrolled in multicenter trial of betamethasone versus placebo for late PTB. Maternal and obstetric characteristics at time of presentation with threatened PTB were compared between those with and without NICU stay ≥3 days. Multivariable logistic regression identified risk factors for NICU stay ≥3 days. RESULT: Of 2795 eligible mother-neonate dyads, 962 (34%) had NICU stay ≥3 days. Gestational age and fetal growth restriction as the reason for threatened PTB had the strongest association with NICU stay ≥3 days in the final model (AUC 0.76). CONCLUSION: Maternal and obstetric characteristics at the time of admission for threatened late PTB should be considered when counseling patients about the probability of NICU stay ≥3 days.

Reflections of an Integrated Maternal-Child Health Medical Student Assignment.

INTRODUCTION: Clinical experiences expose learners to the patient perspective, which can have a lasting impact on students' professional identity. However, in busy clinical settings where opportunities for reflection may be limited, listening to patients' stories is often neglected. We used a reflection assignment to augment a new maternal-child health integrated curriculum. METHODS: Medical students completed a brief assignment from their session in the neonatal intensive care unit (NICU), which included reflective writing, between fall 2016 and summer 2017. The Depth of Reflection rubric was used to score reflections on a scale: "Knowledge and Comprehension" (Level I), "Analysis" (Level II), and "Synthesis and Evaluation" (Level III). A constant comparison method based on grounded theory elicited prenatal and postnatal themes from medical students' reflective writing. RESULTS: All students completed narratives (n = 166); 70% (n = 116) achieved a Depth of Reflection of Level II or III. Six overarching themes emerged: (1) Conception, Pregnancy, and Delivery Experiences; (2) Positive Support Structures; (3) Barriers and Stressors to Care; (4) Future Plans; (5) Unexpected Complications; and (6) Student Career and Professional Considerations. DISCUSSION: Reflections from a novel and brief integrated maternal-child health experience demonstrated high levels on the Depth of Reflection scale. This experience exposed students to core themes central to a family's pregnancy and perinatal experience. Professional identity formation also emerged as a theme. Reflective writing assignments in a busy NICU can facilitate exploration of medical students' knowledge of maternal-child health patient experiences.

Simulation in Neonatal-Perinatal Medicine Fellowship Programs.

OBJECTIVE: This study aimed to investigate the use of simulation in neonatal-perinatal medicine (NPM) fellowship programs. STUDY DESIGN: This was a cross-sectional survey of program directors (PDs) and simulation educators in Accreditation Council for Graduate Medical Education (ACGME) accredited NPM fellowship programs. RESULTS: Responses were received from 59 PDs and 52 simulation educators, representing 60% of accredited programs. Of responding programs, 97% used simulation, which most commonly included neonatal resuscitation (94%) and procedural skills (94%) training. The time and scope of simulation use varied significantly. The majority of fellows (51%) received ≤20 hours of simulation during training. The majority of PDs (63%) wanted fellows to receive >20 hours of simulation. Barriers to simulation included lack of faculty time, experience, funding, and curriculum. CONCLUSION: While the majority of fellowship programs use simulation, the time and scope of fellow exposure to simulation experiences are limited. The creation of a standardized simulation curriculum may address identified barriers to simulation.

Management of diabetic women with threatened preterm birth: a survey of Maternal-Fetal Medicine providers.

Objective: To evaluate variation in management of diabetic women with threatened preterm birth (PTB).Study design: Thirty-two-question electronic maternal-fetal medicine (MFM) provider survey advertised on the Society for MFM website, newsletter, and Facebook page with questions about antenatal steroid use in diabetic women and glycemic management strategy after steroid administration. Descriptive statistics were used to summarize respondent characteristics, practice patterns, and satisfaction with current practice. Multivariable logistic regression was performed to determine if there were any factors independently associated with provider-reported satisfaction.Result: We obtained 159 completed surveys: 69% from board-certified MFM providers and 31% from MFM fellows. Almost half (48%) of respondents reported caring for diabetic women with threatened PTB at least weekly. Overall, 74% were concerned about the risk of maternal hyperglycemia after steroids, but 86% believed the neonatal benefit outweighed maternal risk. More than half (64%) agreed or strongly agreed that steroids for diabetic pregnant women were "evidence-based," and as such, the majority answered that they administer steroids always or most of the time, ranging from 92% for women with uncontrolled type 1 diabetes to 100% for women with diet-controlled gestational diabetes. The frequency of hospitalization and management approach to obtain glycemic control varied by diabetes type and degree of antepartum glycemic control. Two-thirds of MFM providers reported being satisfied with their current practice in caring for these women. Use of a standard protocol for glycemic management was also associated with increased odds of satisfaction (aOR 4.5, 95% CI 1.3-16.1) whereas use of a continuous insulin infusion for all women with insulin-dependent diabetes was associated with decreased odds of satisfaction (aOR 0.3, 95% CI 0.1-0.8). There was no significant association observed between number of years in practice or frequency of care for diabetic women with threatened PTB and provider satisfaction. Overall, 49% of respondents desired a protocol to guide glycemic management, and 74% believed more research is needed to optimize care of diabetic women receiving steroids for threatened PTB.Conclusion: While there are no prospective studies examining the neonatal benefit of antenatal steroids in diabetic women, MFM respondents believe steroid use in this context is evidence-based and report they are administering steroids almost universally in this population. Variation exists in the glycemic management strategy used after steroid administration. While use of a standard protocol for glycemic control was associated with practice satisfaction, routine use of a continuous insulin infusion for all women with insulin-dependent diabetes was associated with lower odds of satisfaction. More research is needed to optimize care of diabetic women receiving steroids for threatened PTB as maternal and neonatal outcomes related to these practices remain unknown.

The Golden Hour: a quality improvement initiative for extremely premature infants in the neonatal intensive care unit.

BACKGROUND: Following delivery, extremely premature infants are vulnerable to rapid development of hypothermia and hypoglycemia. To reduce local rates of these morbidities, a multidisciplinary team developed a protocol standardizing evidence-based care practices during the first hour after birth. METHODS: Using quality improvement methodology, the Golden Hour protocol was implemented for all inborn infants <27 weeks' gestation. Data were collected (2012-2017) over three phases; pre-protocol (n = 80), Phase I (n = 42), and Phase II (n = 92). RESULTS: There were no significant differences in infant characteristics. Improvements in hypothermia (59% vs 26% vs 38%; p = 0.001), hypoglycemia (18% vs 7% vs 4%; p = 0.012), and minutes to completion of stabilization [median (Q1,Q3) 110 (89,138) vs 111 (94,135) vs 92 (74,129); p = 0.0035] were observed. CONCLUSIONS: Implementation of an evidence-based, Golden Hour protocol is an effective intervention for reducing hypothermia and hypoglycemia in extremely premature infants.

The association of pregestational and gestational diabetes with severe neonatal morbidity and mortality.

OBJECTIVE: To estimate the association between maternal diabetes and severe neonatal morbidity. STUDY DESIGN: Retrospective cohort study of nonanomalous neonates born 240-416 weeks' gestation from two large multisite U.S. cohorts, Cesarean Registry and Consortium on Safe Labor. The exposure was pregestational versus gestational versus no diabetes. The composite neonatal outcome included respiratory distress syndrome, mechanical ventilation, necrotizing enterocolitis, grade 3-4 intraventricular hemorrhage, and death. Multivariable logistic regression estimated the association between diabetes and neonatal morbidity. RESULT: Of 196,006 eligible neonates, 2993 (1.5%) were born to mothers with pregestational diabetes and 10,549 (5.4%) with gestational diabetes. Pregestational diabetes was associated with higher odds of neonatal morbidity versus gestational diabetes (aOR 2.27, 95% CI 1.95-2.64), as well as no diabetes (aOR 1.96, 95% CI 1.63-2.35). Gestational diabetes was associated with higher odds of neonatal morbidity versus no diabetes (aOR 1.16, 95% CI 1.04-1.30). CONCLUSION: Pregestational and gestational diabetes are risk factors for severe neonatal morbidity.

Sex-Specific Differences in Late Preterm Neonatal Outcomes.

OBJECTIVE: To estimate sex-specific differences in late preterm outcomes and evaluate whether betamethasone modifies this association. STUDY DESIGN: We conducted a secondary analysis of a multicenter trial of women at risk for late preterm birth randomized to receive betamethasone or placebo. We included women who delivered at 34 to 37 weeks and excluded major fetal anomalies. The primary outcome was severe neonatal morbidity (mechanical ventilation, respiratory distress syndrome, bronchopulmonary dysplasia, sepsis, necrotizing enterocolitis, and intraventricular hemorrhage). Maternal characteristics were compared using chi-square test, t-test, or Mann-Whitney U-test. Multivariable logistic regression estimated the association between sex and morbidity, and likelihood ratio testing assessed for effect modification by betamethasone. RESULTS: Of 2,831 women in the primary trial, 2,331 met the inclusion criteria: 1,236 delivered males and 1,095 delivered females. Betamethasone modified the association between sex and severe morbidity (p = 0.047). Among those who received betamethasone, male sex was associated with higher odds of severe morbidity (adjusted odds ratio: 1.95, 95% confidence interval: 1.25-3.05), compared with female sex. Among those who did not receive betamethasone, there was no significant association between sex and morbidity. CONCLUSION: Male sex is a risk factor for adverse late preterm outcomes, including severe neonatal morbidity after betamethasone receipt.

Practice Variation in Antenatal Steroid Administration for Anticipated Late Preterm Birth: A Physician Survey.

OBJECTIVE: The objective of this study was to measure knowledge and practice variation in late preterm steroid use. STUDY DESIGN: Electronic survey of American College of Obstetricians and Gynecologists (ACOG) members about data supporting the ACOG/Society for Maternal-Fetal Medicine (SMFM) recommendations and practice when caring for women with anticipated late preterm birth (PTB), 340/7 to 366/7 weeks. RESULTS: Of 352 administered surveys, we obtained 193 completed responses (55%); 82.5% were generalist obstetrician-gynecologists (OB/GYNs), and 42% cared for women with anticipated late PTB at least weekly. Most believed that late preterm steroids provided benefit by reducing respiratory distress syndrome (93%), transient tachypnea of the newborn (83%), and neonatal intensive care unit admission (82%). More than half administered late preterm steroids to women with multiple gestations (73%), and pregestational diabetes (55-80%) depending on glycemic control. OB/GYNs administered steroids to insulin-dependent and poorly controlled diabetics more often than MFMs (75 vs. 46% and 59 vs. 37% respectively, p < 0.05 for both). While providers believed there was increased maternal hyperglycemia (88%) and neonatal hypoglycemia (59%), 88% believed neonatal respiratory benefits outweighed these risks. Respondents agreed research is needed to determine who are appropriate candidates (77%) and how to minimize adverse outcomes (82%). CONCLUSION: Most providers are administering late preterm steroids to all women, even those populations who have been excluded from previous trials. Despite widespread use, providers believe more research is needed to optimize management.

Trial Characteristics That Affect Parental Consent in Neonatal Drug Trials.

OBJECTIVE: The main purpose of this article is to determine parental consent rates in neonatal drug trials and describe trial characteristics associated with higher rates. STUDY DESIGN: We included neonatal drug trials published between 2009 and 2014 and compared parental consent rates among the following characteristics: phase type, gestational age, randomization type, drug administration route, drug dosing frequency, blood sampling, control type, length of study, funding source, and length of treatment. We compared characteristics using chi-square, Fisher's exact, one-way analysis of variance or Kruskal-Wallis tests. RESULTS: We identified 52 trials: 38 trials (73%) reported data of parental consent. Median percentage (interquartile range) of parental consent was 79% (62, 89). Higher rates were observed in studies that used active comparators (87%) and shorter study lengths (81% for studies <24 hours). CONCLUSION: Parental consent rates for neonatal drug trials varied by study characteristics. Information on proportion of parents consented is valuable to assess generalizability of trial results and for preparing trial protocols.

Center Variation in the Delivery of Indicated Late Preterm Births.

Objective Evidence for optimal timing of delivery for some pregnancy complications at late preterm gestation is limited. The purpose of this study was to identify center variation of indicated late preterm births. Study design We performed an analysis of singleton late preterm and term births from a large U.S. retrospective obstetrical cohort. Births associated with spontaneous preterm labor, major congenital anomalies, chorioamnionitis, and emergency cesarean were excluded. We used modified Poisson fixed effects logistic regression with interaction terms to assess center variation of indicated late preterm births associated with four medical/obstetric comorbidities after adjusting for socio-demographics, comorbidities, and hospital/provider characteristics. Results We identified 150,055 births from 16 hospitals; 9,218 were indicated late preterm births. We found wide variation of indicated late preterm births across hospitals. The extent of center variation was greater for births associated with preterm premature rupture of membranes (risk ratio [RR] across sites: 0.45-3.05), hypertensive disorders of pregnancy (RR across sites: 0.36-1.27), and placenta previa/abruption (RR across sites: 0.48-1.82). We found less center variation for births associated with diabetes (RR across sites: 0.65-1.39). Conclusion Practice variation in the management of indicated late preterm deliveries might be a source of preventable late preterm birth.

Development and validation of the Proxy-Reported Pulmonary Outcomes Scale for premature infants.

OBJECTIVE: Test the feasibility of using a bedside nurse-reported tool (Proxy-Reported Pulmonary Outcome Scale, PRPOS) for evaluating the severity of bronchopulmonary dysplasia (BPD) by assessing functional, disease-related measures. STUDY DESIGN: Bedside nurses tested the 26-item instrument by observing preterm infants (23-30 weeks at birth) at 36 to 37(4/7) weeks postmenstrual age before, during, and after a care time. We analyzed item reliability, validity, and model fit to determine the six items to include in the final measurement tool. RESULT: We completed assessments on 188 preterm infants. The frequency of an abnormal PRPOS item score increased with increasing National Institute of Child Health and Development (NICHD) BPD category. The six-candidate items produced an internally consistent scale. Addition of the NICHD BPD classification increased reliability moderately; addition of feeding items decreased reliability. The PRPOS score correlated with postmenstrual age at discharge. Infants discharged on oxygen or diuretics had higher median PRPOS scores than did infants who were not prescribed those therapies. CONCLUSION: The PRPOS is an internally consistent, proxy-reported measure of respiratory function in premature infants, based on observable, functional performance measures. Initial testing demonstrates known-groups validity and ongoing testing can assess predictive validity.

Factors Influencing the Accuracy of Noninvasive Blood Pressure Measurements in NICU Infants.

OBJECTIVE: Compare invasive blood pressure (IBP) and noninvasive blood pressure (NIBP) measurement methods in the neonatal intensive care unit (NICU) across various gestational age and postmenstrual age (PMA), and determine the effect of gestational age and PMA on accuracy of NIBP measurements. STUDY DESIGN: Retrospective chart review of paired mean IBP and NIBP measurements from infants admitted to a single NICU from January 2008 through December 2010. Infants with congenital anomalies or receiving therapeutic hypothermia were excluded. Difference between paired measurements was analyzed using Bland-Altman method. We examined the association between PMA, sex, race, mechanical ventilation, medications, and axillary temperature, and the difference in measurements using a mixed effects linear regression model. RESULTS: Eighty-seven infants had 243 observations. The mean (range) gestational age at birth was 31.9 (23-41) weeks and PMA at time of measurement ranged from 26 to 52 weeks. We found poor agreement between IBP and NIBP measurements, with mean difference (95% limits of agreement) of -8.8 (11, -28.7) mm Hg. The mean blood pressure percent difference ( ± SD) was -28.3 ( ± 35.6%). A greater blood pressure percent difference between the two measurement techniques was associated with lower PMA and lower mean IBP. CONCLUSION: NIBP measurements overestimate IBP measurements particularly in smaller, sicker infants at lower IBP measurements.

Diuretic exposure in premature infants from 1997 to 2011.

OBJECTIVE: Diuretics are often prescribed off-label to premature infants, particularly to prevent or treat bronchopulmonary dysplasia. We examined their use and safety in this group. STUDY DESIGN: Retrospective cohort study of infants < 32 weeks gestation and < 1,500 g birth weight exposed to diuretics in 333 neonatal intensive care units from 1997 to 2011. We examined use of acetazolamide, amiloride, bumetanide, chlorothiazide, diazoxide, ethacrynic acid, furosemide, hydrochlorothiazide, mannitol, metolazone, or spironolactone combination. Respiratory support and fraction of inspired oxygen on the first day of each course of diuretic use were identified. RESULTS: About 37% (39,357/107,542) infants were exposed to at least one diuretic; furosemide was the most commonly used (93% with ≥ 1 recorded dose), followed by spironolactone, chlorothiazide, hydrochlorothiazide, bumetanide, and acetazolamide. About 74% patients were exposed to one diuretic at a time, 19% to two diuretics simultaneously, and 6% to three diuretics simultaneously. The most common combination was furosemide/spironolactone, followed by furosemide/chlorothiazide and chlorothiazide/spironolactone. Many infants were not receiving mechanical ventilation on the first day of each new course of furosemide (47%), spironolactone (69%), chlorothiazide (61%), and hydrochlorothiazide (68%). Any adverse event occurred on 42 per 1,000 infant-days for any diuretic and 35 per 1,000 infant-days for furosemide. Any serious adverse event occurred in 3.8 for any diuretic and 3.2 per 1,000 infant-days for furosemide. The most common laboratory abnormality associated with diuretic exposure was thrombocytopenia. CONCLUSION: Despite no Food and Drug Administration (FDA) indication and little safety data, over one-third of premature infants in our population were exposed to a diuretic, many with minimal respiratory support.

Changes in the incidence of candidiasis in neonatal intensive care units.

OBJECTIVE: Neonatal invasive candidiasis is associated with significant morbidity and mortality. We describe the association between invasive candidiasis and changes in use of antifungal prophylaxis, empirical antifungal therapy, and broad-spectrum antibacterial antibiotics over time. METHODS: We examined data from 709,325 infants at 322 NICUs managed by the Pediatrix Medical Group from 1997 to 2010. We determined the cumulative incidence of invasive candidiasis and use of antifungal prophylaxis, broad-spectrum antibacterial antibiotics, and empirical antifungal therapy by year. RESULTS: We identified 2063 (0.3%) infants with 2101 episodes of invasive candidiasis. Over the study period, the annual incidence of invasive candidiasis decreased from 3.6 episodes per 1000 patients to 1.4 episodes per 1000 patients among all infants, from 24.2 to 11.6 episodes per 1000 patients among infants with a birth weight of 750-999 g, and from 82.7 to 23.8 episodes per 1000 patients among infants with a birth weight <750 g. Fluconazole prophylaxis use increased among all infants with a birth weight <1000 g (or <1500 g), with the largest effect on birth weights <750 g, increasing from 3.8 per 1000 patients in 1997 to 110.6 per 1000 patients in 2010. The use of broad-spectrum antibacterial antibiotics decreased among all infants from 275.7 per 1000 patients in 1997 to 48.5 per 1000 patients in 2010. The use of empirical antifungal therapy increased over time from 4.0 per 1000 patients in 1997 to 11.5 per 1000 patients in 2010. CONCLUSIONS: The incidence of invasive candidiasis in the NICU decreased over the 14-year study period. Increased use of fluconazole prophylaxis and empirical antifungal therapy, along with decreased use of broad-spectrum antibacterial antibiotics, may have contributed to this observation.

Influence of neonatal practice variation on outcomes of late preterm birth.

OBJECTIVE: Examine variation in short-term outcomes of late preterm births (34(0/7)-36(6/7) weeks) between a university teaching hospital, teaching community hospital, and nonteaching community hospital. STUDY DESIGN: Review of maternal and newborn data from a random sample of late preterm births at three hospitals in North Carolina from 2008 to 2009. Outcomes included length of stay, neonatal intensive care unit (NICU) admission, respiratory support, antibiotic exposure, phototherapy exposure, and hypoglycemia. RESULTS: We analyzed data from 331 singleton late preterm newborns: 93 (28.1%) from a university teaching hospital, 110 (33.2%) from a teaching community hospital, and 128 (38.7%) from a nonteaching community hospital. Mean gestational age did not vary between hospitals. NICU admission, exposure to antibiotics, and phototherapy were more common at the university teaching hospital after controlling for risk factors, yet length of stay was shortest at the university teaching hospital and longest at the teaching community hospital after adjustment. CONCLUSION: Practice variation contributes to differences in length of stay, NICU admission, and exposure to antibiotics and phototherapy among late preterm newborns. Differences in practice during the birth hospitalization may affect outcomes and health care utilization (e.g., readmission) after discharge.

Regional variation in late preterm births in North Carolina.

Late preterm (LPT) neonates (34 0/7th-36 6/7th weeks' gestation) account for 70% of all premature births in the United States. LPT neonates have a higher morbidity and mortality risk than term neonates. LPT birth rates vary across geographic regions. Unwarranted variation is variation in medical care that cannot be explained by sociodemographic or medical risk factors; it represents differences in health system performance, including provider practice variation. The purpose of this study is to identify regional variation in LPT births in North Carolina that cannot be explained by sociodemographic or medical/obstetric risk factors. We searched the NC State Center for Health Statistics linked birth-death certificate database for all singleton term and LPT neonates born between 1999 and 2006. We used multivariable logistic regression analysis to control for socio-demographic and medical/obstetric risk factors. The main outcome was the percent of LPT birth in each of the six perinatal regions in North Carolina. We identified 884,304 neonates; 66,218 (7.5%) were LPT. After multivariable logistic regression, regions 2 (7.0%) and 6 (6.6%) had the highest adjusted percent of LPT birth. Analysis of a statewide birth cohort demonstrates regional variation in the incidence of LPT births among NC's perinatal regions after adjustment for sociodemographic and medical risk factors. We speculate that provider practice variation might explain some of the remaining difference. This is an area where policy changes and quality improvement efforts can help reduce variation, and potentially decrease LPT births.

Case report: WT1 exon 6 truncation mutation and ambiguous genitalia in a patient with Denys-Drash syndrome.

Denys-Drash syndrome is a rare genetic disorder featuring the triad of congenital nephropathy, Wilms tumor, and intersex disorders (XY under-virilization or XY female). Denys-Drash syndrome is associated with constitutional mutations in the Wilms tumor suppressor gene WT1. Unlike WAGR (Wilms tumor, aniridia, genitourinary anomalies, and mental retardation) syndrome, with its complete deletion of one copy of WT1, Denys-Drash syndrome is generally caused by a dominant-negative mutation. We present a new case of Denys-Drash syndrome in a patient initially diagnosed with XY ambiguous genitalia/partial androgen insensitivity syndrome, who was found to have a novel nonsense mutation in exon 6 leading to a stop codon and hence a truncated protein. Based on lessons learned from this patient, the diagnosis of Denys-Drash syndrome should be considered in the presence of ambiguous genitalia and partial androgen insensitivity.

Estudio mediante Radioinmunoanálisis (RIA) y análisis inmunorradiométrico (IRMA) del equilibrio de la reacción antígeno-anticuerpo de algunas sustancias / Studing of binding antigen-antibody of some substances by means of radioinmunoanalysis (RIA) and inmunoradiometric analysis (IRMA)

Se ha estudiado el equilibrio de la unión, a sus anticuerpos específicos, de las siguientes sustancias: Insulina y dehidroepiandrosterona sulfato (DHEAs), mediante RIA en fase sólida, osteocalcina y fracción c-terminal de la parathormona (PTHc), mediante RIA en disolución y enolasa específica neuronal (NSE), tiroglobulina (Tg) y el marcador tumoral CA549, mediante IRMA. Se pretende determinar un modelo que explique, de manera general, dichas reacciones antígeno-anticuerpo, así como establecer la influencia de algunos factores: temperatura, clase de anticuerpo, reacción en fase sólida o en disolución, características del antígeno, etc., sobre esta unión.Los resultados obtenidos en el estudio del equilibrio no se ajustan al modelo de sitios idénticos e independientes, sin embargo proporcionan un excelente ajuste a la ecuación de Hill.Las reacciones estudiadas presentan un valor bajo de la entalpía de reacción concordante con la naturaleza de la unión antígeno-anticuerpo (AU)