A data-pipeline processing electrocardiogram recordings for use in artificial intelligence algorithms

Introduction

Artificial intelligence (AI) can be used for various tasks in medicine and specifically in cardiology. Medical data such as electrocardiogram recordings (ECGs) are widely used and universally accepted as diagnostic and prognostic tools. It has been shown that deep learning methods using ECGs yield excellent results detecting cardiac pathologies. A significant amount of reliable data is required for supervised learning algorithms such as deep learning models. However, only a small fraction of ECG data generated in daily practice is available in a fully digital and machine-readable format, such as XML. Frequently, used ECG devices produce PDF files or even paper-based print outs, which need to be digitised later for inclusion in clinical information systems. Such ECGs cannot be used without further effort for training or application of deep learning models. Therefore, aim of the present project was to develop a data-pipeline that generates machine-readable ECG data for AI use data irrespective of the initial ECG format.

Methods

We propose an end-to-end pipeline that can not only process data from modern digital ECG devices but is also capable of extracting all necessary information from PDF files (both scanned hard copies and digitally generated PDFs) (see Figure 1). By using different techniques including adaption of open source libraries for vectorisation of image data, and modern computer vision technologies, such as optical character recognition (OCR), our pipeline is able to flexibly process data from different recording devices and read both data in PDF format and data from native digital devices delivered in XML. The processed files from various sources are either saved as a common and easily accessible CSV file format, or are processed directly with deep learning models (see Figure 2).

Results

The developed data-pipeline was validated using data from a set of 113 12-lead ECGs for which data was available in multiple formats. Each format dataset was separately processed by our pipeline and then used for training and validation of a deep learning architecture for myocardial scar detection based on raw ECG signals. The quality of the extraction process by our pipeline was assessed by the respective deep learning models with their prediction capability depicted by receiver operator characteristic analyses (ROC). Comparing the benchmark model that was generated from XML data against a model that was purely trained on PDF data processed by the pipeline shows that both models produced comparable results, reaching area under the curve (AUC) values of 0:79±0:10 (XML) and 0:83±0:07 (PDF).

Conclusion

The data pipeline facilitates acceleration of ECG-based AI research and application of AI algorithms by providing access to ECG data irrespective of the format of the stored ECG. Future work will focus on independent validation as well as expanding this pipeline to include additional ECG types.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): Flexi Funds by Forschungscampus Mittelhessen

Area-level and individual correlates of active transportation among adults in Germany: A population-based multilevel study

This study aimed at estimating the prevalence in adults of complying with the aerobic physical activity (PA) recommendation through transportation-related walking and cycling. Furthermore, potential determinants of transportation-related PA recommendation compliance were investigated. 10,872 men and 13,144 women aged 18 years or older participated in the cross-sectional 'German Health Update 2014/15 - EHIS' in Germany. Transportation-related walking and cycling were assessed using the European Health Interview Survey-Physical Activity Questionnaire. Three outcome indicators were constructed: walking, cycling, and total active transportation (≥600 metabolic equivalent, MET-min/week). Associations were analyzed using multilevel regression analysis. Forty-two percent of men and 39% of women achieved ≥600 MET-min/week with total active transportation. The corresponding percentages for walking were 27% and 28% and for cycling 17% and 13%, respectively. Higher population density, older age, lower income, higher work-related and leisure-time PA, not being obese, and better self-perceived health were positively associated with transportation-related walking and cycling and total active transportation among both men and women. The promotion of walking and cycling among inactive people has great potential to increase PA in the general adult population and to comply with PA recommendations. Several correlates of active transportation were identified which should be considered when planning public health policies and interventions.

[Metabolic disorders as paraneoplastic syndromes]

Paraneoplastic syndromes are characterized by the tumor-induced release of peptide hormones and/or the initiation of immune phenomena, which elicit clinical changes and alterations in laboratory parameters independent of the tumor size and spread. In addition to neurological, endocrinal and rheumatological phenotypes, metabolic alterations play a special role in the clinical routine as they commonly present with acute symptoms in an emergency situation and necessitate immediate diagnosis and prompt initiation of treatment. Metabolic alterations within the framework of malignant diseases should be treated in a multidisciplinary team and it is often necessary to perform monitoring and treatment in an intensive care unit. This article focuses on the diagnostic and therapeutic options for metabolic disorders due to paraneoplastic syndromes, such as hypercalcemia, hypocalcemia, hyperglycemia, hypoglycemia and a special variant of tumor-induced metabolic disorders due to tumor lysis syndrome.

Relevance of dihydropyrimidine-dehydrogenase and thymidylate-synthase in patients with pancreatic neuroendocrine neoplasms treated with 5-FU-based chemotherapy

BACKGROUND

Chemotherapy with 5-FU and Streptozotocin (STZ) is recommended as first-line treatment in patients with metastatic pancreatic neuroendocrine neoplasms (PNEN). However, data about biomarkers involved in the 5-FU metabolism to predict response are still limited.

OBJECTIVES

Evaluation of clinicopathological features and potential predictive and prognostic markers of patients with PNEN treated with 5-FU based regimens.

PATIENTS AND METHODS

We retrospectively analyzed 41 patients with PNEN who were treated at the University Hospital Marburg between 2000 and 2013. Dihydropyrimidine-Dehydrogenase (DPD) and Thymidylate-Synthase (TS) expression was correlated with treatment response in 19 patients who had available tumour tissue and response data. The median overall survival (OS) and progression free survival (PFS) were calculated using Kaplan-Meier and Cox regression methods, respectively.

RESULTS

The median PFS in patients receiving 5-FU/STZ was 17 months with a median OS of 50 months. Objective response rate (ORR) and disease control rate (DCR) were 32% and 73%, respectively. Biochemical response (p = 0.005) and high DPD expression (p = 0.018) were predictive markers of response to 5-FU-based chemotherapy. Univariate analysis identified Ki-67 > 10%, no biochemical response, positive 5-HIAA levels and TS deficiency as independent risk factors for shorter PFS. Moreover, performance status (PS) ≥1 was an independent risk factors for impaired OS.

CONCLUSIONS

DPD expression and biochemical response represent promising predictive biomarkers for response to 5-FU based chemotherapy. Moreover, Ki-67, PS and TS are independent prognostic markers of OS and PFS in patients with PNEN.

[The influence of Nintendo-Wii® bowling upon residents of retirement homes]

The few studies dealing with the positive effects of health and well-being of older people are only one-sided. The aim of the study therefore was to analyze the effects of Nintendo-Wii® bowling on daily function, state of dementia, quality of life, cognition and motor skills in retirement home inhabitants. The study was performed with 27 study participants (13 women, 14 men) between the ages of 49 and 95 years (mean = 71, SD = 14). They were randomly assigned to a control group (KG) and an intervention group (IG). Between pre- and posttest, the IG played 60 min/twice a week Nintendo-Wii® Bowling over 6 weeks. The improvement of IG was significant in the analysis of variance concerning strength (arm curls: F df = 2 = 7.199; p = 0,013; η(2) = 0,231) and showed a significant trend concerning coordination (tracking lines: F df = 2 = 3.99; p = 0,058; η(2) = 0,154) compared with KG. The area of rapidity (catching bars: F df = 2 = 28.511; p = 0,008; η(2) = 0,279) showed a significant decline in the IG compared with the KG. However, closer examination shows that the short time of intervention and the wide age range could have affected the results. Thus, further studies should take these critical aspects into consideration.

Differential control of sex differences in estrogen receptor α in the bed nucleus of the stria terminalis and anteroventral periventricular nucleus

The principal nucleus of the bed nucleus of the stria terminalis (BNSTp) and anteroventral periventricular nucleus of the hypothalamus (AVPV) are sexually dimorphic, hormone-sensitive forebrain regions. Here we report a profound sex difference in estrogen receptor-α (ERα) immunoreactivity (IR) in the BNSTp, with robust ERα IR in females and the near absence of labeling in males. This sex difference is due to the suppression of ERα IR by testicular hormones in adulthood: it was not present at birth and was not altered by neonatal treatment of females with estradiol; gonadectomy of adult males increased ERα IR to that of females, whereas gonadectomy of adult females had no effect. Treating gonadally intact males with an aromatase inhibitor partially feminized ERα IR in the BNSTp, suggesting that testicular suppression required aromatization. By contrast, in AVPV we found a modest sex difference in ERα IR that was relatively insensitive to steroid manipulations in adulthood. ERα IR in AVPV was, however, masculinized in females treated with estradiol at birth, suggesting that the sex difference is due to organizational effects of estrogens. The difference in ERα IR in the BNSTp of males and females appears to be at least in part due to greater expression of mRNA of the ERα gene (Esr1) in females. The sex difference in message is smaller than the difference in immunoreactivity, however, suggesting that posttranscriptional mechanisms also contribute to the pronounced suppression of ERα IR and presumably to functions mediated by ERα in the male BNSTp.

[A 79-year-old man with B symptoms and jaw claudication]

A 79-year-old patient presented with weight loss, subfebrile body temperature and unclear jaw pain. After ruling out malignant and infectious causes, positron emission tomography-computed tomography (PET-CT) revealed markedly elevated glucose utilization of the large thoracic and upper limb arteries, suggesting systemic vasculitis. Color-coded duplex sonography confirmed thickening of the wall of the external carotid artery consistent with vasculitis. The patient was diagnosed with giant cell arteritis involving the large thoracic arteries and the upper limb arteries but without involvement of the superficial temporal artery. Based on the involvement of the external carotid artery, the jaw pain could be classified as jaw claudication. Clinical and laboratory remission was achieved with systemic glucocorticoids which could subsequently be tapered. The patient is well and asymptomatic 12 months after diagnosis and 2 months without steroids.

Successful selective internal radiotherapy (SIRT) in a patient with a malignant solid pseudopapillary pancreatic neoplasm (SPN)

Solid pseudopapillary neoplasms of the pancreas (SPNs, Gruber-Frantz-Tumor) are a rare entity representing 1-5% of all exocrine pancreatic tumors. The pseudocystic lesions preferentially affect young females <30 years, are mostly benign (∼90%) and normally present with unspecific symptoms. We describe the case of a 16-years-old Asian woman that was initially diagnosed with an SPN in the pancreatic head with mesenterial and hepatic metastases. After diagnosis, an extensive tumor resection was performed including pyloric-preserving pancreatic head resection followed by sequential resection of all hepatic metastases. After the patient was diagnosed with a hepatic recurrence and high intrahepatic tumor load, we chose a multimodal procedure and performed a selective internal radiotherapy (SIRT). Four years after SIRT and 10 years after initial diagnosis of metastatic SPN, the patient is in a good condition without any evidence for hepatic recurrence. This case represents a rare clinical course of a malignant and invasive SPN with an exceptionally long survival despite of high initial tumor burden. The selective internal radiotherapy is a suitable approach for inducing long-term remissions of the strongly vascularized liver metastases.

[Relationship between physical activity and health in children and adolescents. Results of the German Health Interview and Examination Survey for Children and Adolescents (KiGGS) and the "Motorik-Modul" (MoMo)]

The question of whether physical activity is associated with positive aspects of health becomes increasingly more important in the light of the health status in today's children and adolescents and due to the changing lifestyle with respect to everyday activity. The German Health Interview and Examination Survey for Children and Adolescents (KiGGS) collected the first set of nationwide representative cross-sectional data to examine the relationship between health and physical activity. Taking sociodemographic parameters into consideration, the results suggest a positive association between self-estimated general health and several types of physical activity. The results vary with respect to gender and type of physical activity. For methodological reasons, causal conclusions can only be drawn after longitudinal data of the second wave of KiGGS are available.

[The tight junction proteins expression in the epithelium of the small intestines in a rat]

Proteins' expression of tight junction proteins in rat small intestine was analyzed by means of immunohistochemistry and Western blotting. Claudins -1, -2, -3, -4, -5, -7 and occludin were analyzed. Confocal laser-scanning microscopy revealed differences in the subcellular distributions of these proteins. Claudins-1, -2, -3, -4, -5, and -7 were localized within the tight junction complex and were also detectable in subjunctional regions. Distributed subcellular localization of these proteins may reflect their different roles during formation of epithelial cell layers as well as in paracellular transport of ions in the small intestine.

[Sex-specific aspects of addiction]

Addictive diseases such as alcoholism, nicotine or opiate addiction show sex-specific characteristics. These apply to epidemiological data, the psychosocial conditions for the development of the addiction,the symptoms, possible consequences for pregnancy and breastfeeding, the course of the addiction, as well as its treatment. As a whole, men are more frequently substance-dependent than women. This is true for all types of addiction and for each individual substance - with the exception of benzodiazepines and analgesics to which women are equally or more frequently dependent. Moreover, women have a different consumption pattern from men. Epidemiological surveys on illegal drugs frequently do not present sex-specific data. There also is still a great need for research in regards to sex-specific therapeutic strategies.

Effect of treatment with prostaglandin E1 and N-acetylcysteine on pediatric liver transplant recipients: a single-center study

Prostaglandin E1 (PGE1) and N-acetylcysteine (NAC) have been used as single agents to decrease reperfusion injury and improve outcome after solid-organ transplantation (Tx). We hypothesized that combined treatment with NAC and PGE1 would be safe and reduce reperfusion injury. We therefore carried out a pilot study to assess the safety of this drug combination and gain information regarding the efficacy of treating pediatric liver transplant recipients with NAC and PGE1. The pilot study took the form of an open-label study incorporating 25 pediatric liver transplant recipients (12 children in the treatment group and 13 children as controls). NAC (70 mg/kg) was given intravenously over 1 h following reperfusion and then every 12 h for 6 days. PGE1 (0.4 mg/kg/h) was given as a continuous intravenous infusion for 6 days, starting after the first NAC dose. The primary outcome was the safety of combined treatment with NAC and PGE1. Patient survival, graft survival, allograft rejection within the first 90 days after Tx, peak post-transplant serum alanine aminotransferase (ALT) concentration, post-transplant length of hospitalization, and post-operative complications were secondary outcomes. Post-operative complications occurred at similar rates in both control and treated groups. No complications or adverse events occurred in the treated group as a result of study drugs. The 3-month patient survival rate was 100% for both groups. For the group treated with NAC and PGE1, peak serum ALT was lower and median length of stay was shorter but the differences did not reach statistical significance. The proportion of patients with allograft rejection was not significantly different between the two groups. However, rejection was more severe in the control group than in the treated group. In summary, infusions of NAC and PGE1 were safely administered to pediatric liver transplant recipients. However, a randomized controlled study is needed to determine the efficacy of treatment with NAC and PGE1.

Quantitative and functional analysis of core-specific T-helper cell and CTL activities in acute and chronic hepatitis B

AIMS/BACKGROUND

CD4+ T-helper cell (Th) responses to hepatitis B virus (HBV) core antigen (HBc) are increased during exacerbations in acute and chronic hepatitis B (AHB, CHB) and might influence the induction of CD8+ cytotoxic T lymphocytes (CTL) that are important for viral clearance.

METHODS

HBc-specific proliferative responses and cytokine release of blood mononuclear cells (PBMC) were studied in patients with AHB or CHB, as well as responders and non-responders to interferon-alpha treatment (IFN-R, IFN-NR), by [3H]-thymidine-uptake, enzyme-linked immunosorbent assay (ELISA) and Elispot assay and were compared to peptide HBc18 27-specific CTL precursor frequencies among CD8+ T cells derived from HLA-A2+ patients.

RESULTS

HBc-specific proliferative PBMC responses and Th frequencies were significantly increased in AHB patients compared with untreated CHB patients. PBMC derived from IFN-R showed stronger cellular responses than IFN-NR. Stimulated PBMC from all patient groups secreted significantly more IFN-gamma than IL-4 indicating Th1/Th0 cell responses. Furthermore, in AHB and IFN-R patients, high peptide HBc18-27-specific CTL precursor frequencies closely correlated with strong HBc-specific Th responses, whereas in untreated CHB and IFN-NR patients lower CTL frequencies were observed without correlation to Th activities.

CONCLUSIONS

HBV core-specific Th-cell responses appeared to support efficient CTL induction in patients with viral clearance, whereas in chronic HBV carriers quantitatively insufficient Th and CTL responses were observed. This observation could be important for future therapeutic strategies.

Pediatric blunt cardiac injury: epidemiology, clinical features, and diagnosis. Pediatric Emergency Medicine Collaborative Research Committee: Working Group on Blunt Cardiac Injury

AIM

The goal of this study was to describe the epidemiology, clinical presentation, diagnostic methods, and outcome in a large series of children with blunt cardiac injury (BCI).

METHODS

A multicenter retrospective review of all individuals less than 18 years of age diagnosed with a BCI from 1983 to 1993 was conducted. Cases included all those with a discharge diagnosis of myocardial contusion, concussion, ventricular disruption, or unspecified BCI.

RESULTS

A total of 184 cases of BCI were identified in 16 participating centers. The median age was 7.4 years, and 73% were male. Myocardial contusions accounted for 95% of the diagnoses. The leading mechanisms were motor vehicle crashes involving a pedestrian (39.7%) or passenger (31.0%). The majority (87%) had multiple system trauma, with a mean Injury Severity Score of 27.2 (SD +/- 14.4). Pulmonary contusions were present in 50.5% and rib fractures in 23.0%. The most common diagnostic test performed was a 12-lead electrocardiogram (EKG) (82%), followed by a MB band of creatine phosphokinase (CPK-MB) (69%) and echocardiogram (65%). All three tests were performed in 50%. In these patients, agreement among various diagnostic test pairs was fair (echocardiogram vs. EKG, kappa = 0.27) to poor (echocardiogram vs. CPK-MB, kappa = 0.07 and EKG vs. CPK-MB, kappa = 0.08). No hemodynamically stable patient who presented with a normal sinus rhythm subsequently developed a cardiac arrhythmia or cardiac failure. There were 25 deaths (13.6%), 3 of which were caused by acute pump failure secondary to massive cardiac injury. The remainder died of head or abdominal injuries. Of the 159 (86.4%) patients surviving, 8 (5% of survivors) had significant cardiac sequela, most commonly mitral or tricuspid insufficiency or ventricular septal defect.

CONCLUSIONS

Pediatric BCI is usually diagnosed in the context of severe multiple system trauma and is less commonly an isolated event. Because of the lack of a standard, various diagnostic tests are used in the diagnosis of BCI, and these tests rarely agree. In hospitalized pediatric patients with BCI, unanticipated complications are rare. Significant sequela, although uncommon, do occur and follow-up of children with BCI should be ensured.

Pediatric emergency medicine fellow clinical work requirements

A wide range of clinical requirements exists among PEM fellowship programs. Programs are equally split concerning the question of whether fellows should work with supervision or independently in the first year; a significant number of fellowship programs require continued supervision of fellows in subsequent years. Orientation for first year fellows and requirements for completion of PALS, advanced pediatric life support (APLS), ACLS, or ATLS courses prior to their first independent shift varied greatly. In particular, a minority of programs required ATLS completion even though a majority of overall fellowship programs operate in a hospital designated as a Level 1 Trauma Center. Programs in which first-year fellows worked independently had fewer attendings and were less likely to provide 24-hour coverage. Fellows appear to work a similar or less demanding schedule than PEM attendings in most fellowship programs, and most fellowship directors feel that their fellows should continue with their current schedule.

[Characterization of 24-hour survival rate and duration of survival of hydroxyethyl starch cryopreserved erythrocytes after autologous transfusion in the dog]

BACKGROUND

Cryopreservation of erythrocytes using hydroxyethyl starch (HES) as cryoprotecting additive could result in a nearly unlimited storage stability of preserved red cells. In addition, it would allow its immediate use for transfusion. In order to assess the therapeutic efficacy of erythrocytes cryopreserved with HES, their 24-hour post-transfusion survival and long-term survival was evaluated.

MATERIALS AND METHODS

The experiments were carried out with dog erythrocytes as an animal model for human erythrocytes. To each of 6 German shepherd dogs a 15-ml sample of erythrocyte suspension, labeled with 51Cr (25 microCi) after thawing, was autologously injected. Caused by hemolysis 29% of the formerly cryopreserved erythrocytes have not been labeled. To each of 6 control animals 15 ml of a suspension of freshly drawn and 51Cr-labeled erythrocytes was injected. The 51Cr radioactivity in later taken blood samples was a measure for the number of injected erythrocytes having remained in the circulation until the moment of blood withdrawal. The effect of cryopreservation was assessed by comparison of the test group with the control group.

RESULTS

In both groups 30% of the applied cells left the circulation within 30 min. This was effected by pharmacological enlargement of the dogs' spleen and not by hemolysis of the erythrocytes. After the first 24 h all of the cryopreserved labeled erythrocytes had survived to the same amount (> 95%) as the labeled fresh red cells. Between 12 h and 20 days after injection, in both groups the 51Cr activity decreased exponentially by 4.8 and 4.5%/d. This difference was not significant. The area under the curve amounted to 1253 and 1257% d, respectively.

CONCLUSIONS

There exists a subpopulation of red cells that is destroyed by freezing stress. As a result the freed stroma would be a serious transfusion risk. All erythrocytes having survived the cryopreservation procedure resemble the fresh erythrocytes with regard to the in-vivo survival; their therapeutic efficacy is not impaired. In the context of in-vitro results with human erythrocytes it can be expected that at the present developmental state of the cryopreservation procedure at least 93% of the human erythrocytes cryopreserved with HES have a normal 24-hour and long-term post-transfusion survival.

Charakterisierung der 24-Stunden-Überlebensrate und Lebensdauer von mittels Hydroxyethylstärke kryokonservierten Erythrozyten nach autologer Transfusion im Hund

<i>Hintergrund:</i> Die Kryokonservierung von Erythrozyten unter Verwendung von Hydroxyethylstärke (HES) als Gefrierschutzadditiv würde die nahezu unbegrenzte Haltbarkeit eines Erythrozytenkonzentrates, verbunden mit seiner sofortigen Ver-fügbarkeit nach Auftauen, ermöglichen. Zur Beurteilung der therapeutischen Wer-tigkeit solcher Erythrozyten wurde ihre In-vivo-24-Stunden-Überlebensrate und Lebensdauer am Modell Hundeerythrozyt charakterisiert. <i>Material und Methodik:</i> Sechs Schäferhunde erhielten je 15 ml kryokonservierte und nach dem Auftauen mit ⁵¹Cr (25 µCi) markierte Erythrozyten. Sechs Kontrolltiere erhielten Cr-markierte Nativerythrozyten. Wegen Hämolyse nach dem Auftauen gelangten 29% der kryokonservierten Erythrozyten nicht zur Markierung. Zu definierten Zeitpunkten wurden den Tieren Blutproben entnommen und darin die ⁵¹Cr-Radioaktivität als Maß für die Zahl der bis zum Zeitpunkt der Probenentnahme in der Zirkulation verbliebenen Erythrozyten gemessen. Beurteilungsgrundlage für die Wirkung der Kryokonservierung war der Vergleich der Verumgruppe mit der Nativgruppe. <i>Ergebnisse:</i> Alle markierten kryokonservierten Erythrozyten überlebten die ersten 24 Stunden in vergleichbarer Rate ( > 95%) wie die markierten Nativerythrozyten. Dabei verließen in den ersten 30 min aus verteilungskinetischen Gründen 30% der applizierten Zellen die Zirkulation. Zwischen 12 h und 20 Tagen nahm die ⁵¹Cr-Aktivität bei beiden Versuchsgruppen exponentiell um etwa 4,8 bzw. 4,5%/Tag ab. Der Unterschied war nicht signifikant. Das Impuls-Zeit-Integral für diesen Zeitraum betrug 1253 bzw. 1257% Tage. <i>Schlußfolgerungen:</i> Es existiert eine Erythrozyten-Subpopulation, die durch den Frier/Tau-Prozeß zur Lyse gebracht wird und durch ihr stromahaltiges Hämoglobin ein ernstes Transfusionshindernis darstellen könnte. Alle die Kryokonservierung mit HES überlebenden Erythrozyten gleichen in ihrer Lebensdauer den Nativerythrozyten, ihre therapeutische Wertigkeit ist nicht eingeschränkt. Zusammen mit In-vitro-Befunden an Humanerythrozyten lassen die Ergebnisse erwarten, daß beim

Subretinal neovascularization as a complication of drainage of subretinal fluid

Four cases of subretinal choroidal neovascularization that developed at the sight of breaks in Bruch's membrane were made for the drainage of subretinal fluid during retinal reattachment surgery. This neovascularization can occur in both young and older patients. All drainage sights were posterior to the equator, which may indicate a higher risk of the development of this complication from posterior drainage sights. Unless the fovea is threatened, there is no urgency to treat this choroidal neovascularization. It is unclear why this complication is so rare, considering the frequency of surgical perforation of the choroid and Bruch's membrane during drainage of subretinal fluid in retinal reattachment surgery.

Development of parathyroid hormone- and calcitonin-activated adenylate cyclases in embryonic chicken limb and in cultured cells from embryonic chicken limb

Activation of adenylate cyclase [ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1] by parathyroid hormone (PTH) and calcitonin was measured as a function of stage of development in embryonic chicken limb buds. Responsiveness to both hormones develops in the tissue at the time when nascent bone is forming. In addition, a temporal sequence of development of hormone response was observed, with a PTH-activated adenylate cyclase appearing earlier than the calcitonin-activated enzyme. The responsiveness to the two hormones was additive, indicating the presence of two receptor populations. Undifferentiated cells obtained from limb buds prior to appearance of hormonal responsiveness were cultured and were found to develop a PTH-activated adenylate cyclase in vitro. However, a calcitonin-stimulated enzyme did not appear in such cultures. The PTH-activated enzyme was found to be similar to that present in bone in regard to its sensitivity to PTH. The enzyme did not respond to other hormones, and myoblast cultures did not develop a PTH-activated adenylate cyclase, indicating that a true bone adenylate cyclase was being measured.