Personality processes of everyday moral courage

INTRODUCTION

Moral courage manifests in acts intended to intervene to stop or redress witnessed moral norm violations, despite the risk of negative consequences for the intervener. We investigate moral courage in everyday life and ask what personality processes are involved. Based on an extended process model of moral courage, we derived hypotheses on cognitive and emotional processes that should facilitate or hinder intervention. Further, we identified candidate personality dispositions that should shape these processes and thereby predict who tends to intervene against others' norm violations and who does not.

METHODS

Using a quota-based sample of the German population (N = 1108), we conducted a personality assessment, followed by a 7-day experience sampling during which participants reported norm violations witnessed in their daily life as well as their cognitive, emotional, and behavioral reactions.

RESULTS

In total, 678 participants reported 1965 norm violations and intervened against 32% of them. Dispositional self-efficacy facilitated intervention by increasing a sense of efficacy when confronted with others' norm violations. Conversely, dispositional moral disengagement hindered intervention by reducing perceived own responsibility.

DISCUSSION

Our findings provide novel insights into the situations affording moral courage in everyday life, and the personality processes that uniquely guide this behavior.

An Annotation Workbench for Semantic Annotation of Data Collection Instruments

Semantic interoperability, i.e., the ability to automatically interpret the shared information in a meaningful way, is one of the most important requirements for data analysis of different sources. In the area of clinical and epidemiological studies, the target of the National Research Data Infrastructure for Personal Health Data (NFDI4Health), interoperability of data collection instruments such as case report forms (CRFs), data dictionaries and questionnaires is critical. Retrospective integration of semantic codes into study metadata at item-level is important, as ongoing or completed studies contain valuable information, which should be preserved. We present a first version of a Metadata Annotation Workbench to support annotators in dealing with a variety of complex terminologies and ontologies. User-driven development with users from the fields of nutritional epidemiology and chronic diseases ensured that the service fulfills the basic requirements for a semantic metadata annotation software for these NFDI4Health use cases. The web application can be accessed using a web browser and the source code of the software is available with an open-source MIT license.

How prosocial is moral courage?

Moral courage, that is, defending moral beliefs despite personal risks, is often seen as a hallmark of prosocial behavior. We argue that prosociality in moral courage is, however, complex. While its prosociality is often evident at a higher societal level, it can be contested in some aspects of morally courageous acts. We review the literature on two such aspects and highlight that differences and conflicts in moral beliefs, as well as the confrontational nature of many morally courageous acts, call into question prosociality. We recommend that future research takes the complexity of prosociality in moral courage into account to obtain a comprehensive and nuanced understanding of the psychological underpinnings of moral courage and its contributions to the functioning of societies.

The functions of anger in moral courage-Insights from a behavioral study

Moral courage is manifested when bystanders intervene to stop or prevent others' norm transgressions, despite potential costs to themselves. Although theoretical models propose a key role of emotions, in particular anger, in the psychological processes underlying moral courage, to date this role is underexplored. In a behavioral study, we proposed a conceptual differentiation between experienced and expressed anger in response to a witnessed moral transgression. By staging the embezzlement of money from project funds in the lab, we tested whether anger arises in response to a witnessed moral norm transgression and scrutinized its unique contribution to predicting who intervenes and who remains inactive in the context of other theoretically relevant emotions (guilt, fear, and empathy). In addition, we investigated the role of bystanders' anger expression in response to the transgression. Lastly, we tested whether experienced and expressed anger reactions were predicted across time from dispositions. Our paradigm allowed us to obtain observational data of behavioral responses and anger expression and experienced emotion reports in response to a realistic moral norm transgression. Results showed that experienced anger increased after the transgression and uniquely predicted intervention. Experienced anger reaction was predictable across time from dispositional sensitivity to observed injustice. Anger expression was only loosely associated with anger experience and intervention, suggesting it may constitute a display of disapproval in itself. The present findings from a realistic moral transgression situation evidence the important role of anger in the psychological process underlying moral courage. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

[Four years after the Ebola crisis : Challenges, experiences, and implications in the German public health context]

The Ebola virus disease outbreak in West Africa in 2014/2015 was by far the biggest, most prolonged, and geographically most widespread outbreak of this disease since the discovery of the Ebola virus in 1976. Although no cases of Ebola virus disease were confirmed in Germany, a number of crisis management activities were initiated.Based on a combination of local, national, and international lessons learned, literature research, and a large number of discussions among German colleagues as well as German and foreign colleagues, the experiences of selected German public health actors as well as implications for health protection activities in Germany are presented.On the one hand, preparedness for managing unusual high consequence health events-caused by rare, highly pathogenic biological agents-including the provision of adequate material and personnel resources remains important in Germany. On the other hand, more German engagement in global health is necessary, because the dividing line between global health and local health is increasingly disappearing.

Zoonotic origin and transmission of Middle East respiratory syndrome coronavirus in the UAE

Since the emergence of Middle East respiratory syndrome coronavirus (MERS-CoV) in 2012, there have been a number of clusters of human-to-human transmission. These cases of human-to-human transmission involve close contact and have occurred primarily in healthcare settings, and they are suspected to result from repeated zoonotic introductions. In this study, we sequenced whole MERS-CoV genomes directly from respiratory samples collected from 23 confirmed MERS cases in the United Arab Emirates (UAE). These samples included cases from three nosocomial and three household clusters. The sequences were analysed for changes and relatedness with regard to the collected epidemiological data and other available MERS-CoV genomic data. Sequence analysis supports the epidemiological data within the clusters, and further, suggests that these clusters emerged independently. To understand how and when these clusters emerged, respiratory samples were taken from dromedary camels, a known host of MERS-CoV, in the same geographic regions as the human clusters. Middle East respiratory syndrome coronavirus genomes from six virus-positive animals were sequenced, and these genomes were nearly identical to those found in human patients from corresponding regions. These data demonstrate a genetic link for each of these clusters to a camel and support the hypothesis that human MERS-CoV diversity results from multiple zoonotic introductions.

Event-related potentials in response to cheating and cooperation in a social dilemma game

A sequential prisoner's dilemma game was combined with psychophysiological measures to examine the cognitive underpinnings of reciprocal exchange. Participants played four rounds of the game with partners who either cooperated or cheated. In a control condition, the partners' faces were shown, but no interaction took place. The partners' behaviors were consistent in the first three rounds of the game, but in the last round some of the partners unexpectedly changed strategies. In the first round of the game, the feedback about a partner's decision elicited a feedback P300, which was more pronounced for cooperation and cheating in comparison to the control condition, but did not vary as a function of feedback valence. In the last round, both the feedback negativity and the feedback P300 were sensitive to expectancy violations. There was no consistent evidence for a negativity bias, that is, enhanced allocation of attention to feedback about another person's cheating in comparison to feedback about another person's cooperation. Instead, participants focused on both positive and negative information, and flexibly adjusted their processing biases to the diagnosticity of the information. This conclusion was corroborated by the ERP correlates of memory retrieval. Successful retrieval of a partner's reputation was associated with an anterior positivity between 400 and 600 ms after face onset. This anterior positivity was more pronounced for both cooperator and cheater faces in comparison to control faces. The results suggest that it is not the negativity of social information, but rather its motivational and behavioral relevance that determines its processing.

Continued vigilance - development of an online evaluation tool for assessing preparedness of medical facilities for biological events

OBJECTIVE

Effective response to biological events necessitates ongoing evaluation of preparedness. This study was a bilateral German-Israeli collaboration aimed at developing an evaluation tool for assessing preparedness of medical facilities for biological events.

METHODS

Measurable parameters were identified through a literature review for inclusion in the evaluation tool and disseminated to 228 content experts in two modified Delphi cycles. Focus groups were conducted to identify psychosocial needs of the medical teams. Table-top and functional exercises were implemented to review applicability of the tool.

RESULTS

One hundred seventeen experts from Germany and Israel participated in the modified Delphi. Out of 188 parameters that were identified, 183 achieved a consensus of >75% of the content experts. Following comments recommended in the Delphi cycles, and feedback from focus groups and hospital exercises, the final tool consisted of 172 parameters. Median level of importance of each parameter was calculated based on ranking recommended in the Delphi process. Computerized web-based software was developed to calculate scores of preparedness for biological events.

CONCLUSION

Ongoing evaluation means, such as the tool developed in the study, can facilitate the need for a valid and reliable mechanism that may be widely adopted and implemented as quality assurance measures. The tool is based on measurable parameters and indicators that can effectively present strengths and weaknesses in managing a response to a public health threat, and accordingly, steps can be implemented to improve readiness. Adoption of such a tool is an important component of assuring public health and effective emergency management.

Unfinished business: efforts to define dual-use research of bioterrorism concern

Biotechnological research poses a special security problem because of the duality between beneficial use and misuse. In order to find a balance between regulating potentially dangerous research and assuring scientific advancement, a number of assessments have tried to define which types of research are especially open to misuse and should therefore be considered dual-use research of special concern requiring rigorous oversight. So far, there has been no common understanding of what such activities are. Here we present a review of 27 assessments focusing on biological dual-use issues published between 1997 and 2008. Dual-use research activities identified by these assessments as being of special concern were compiled and compared. Moreover, from these 27 assessments, the primary research publications explicitly identified as examples of concerning research activities were extracted and analyzed. We extracted a core list of 11 activities of special concern and show that this list does not match with the reasons why primary research publications were identified as being of special concern. Additionally, we note that the 11 activities identified are not easily conducted or replicated, and therefore the likelihood of their being used in a high-tech mass casualty bioterrorism event should be reevaluated.

Disseminated multiorgan MDR-TB resistant to virtually all first-line drugs

The emergence of multidrug-resistant tuberculosis (MDR-TB) is a major global concern since, despite a complex treatment regime, it still remains a lethal threat. A 21-yr-old male HIV-negative migrant from Burma presented with a disseminated tuberculosis affecting the lung, spleen, liver, mediastinal and abdominal lymph nodes. This particular strain of Mycobacterium tuberculosis proved to be resistant to all but one (pyrazinamide) of the first-line drugs, i.e. rifampicin, isoniazid and ethambutol, plus streptomycin, rifabutin and ofloxacin. On the mere account of its susceptibility concerning kanamycin it could not be labelled as extensively drug-resistant tuberculosis. After 1month of a standard first-line four-drug regimen and a subsequent 4months of second-line treatment with amikacin, moxifloxacin, terizidone, protionamide, linezolid and pyrazinamide, sputum cultures eventually yielded constantly negative results. Likewise, the organ manifestations decreased significantly, so as to be virtually undetectable in computed tomography scans after 1yr of continuous treatment. A moderate pancytopenia reversed completely after dose adjustment of linezolid. Disseminated tuberculosis manifestations without typical pulmonary cavernous lesions are likely to represent primary infection rather than reactivation. Even a multiorgan disseminated MDR-TB with an extensive resistance pattern (including fluoroquinolones) can be successfully treated with an individual second-line treatment and result in considerably few adverse events.

[Specific aspects of treatment for women with bipolar affliction]

This manuscript summarizes specific issues in the disease course and pharmacological treatment of women with bipolar disorders. Gender differences relevant to the female biology manifest in symptoms, outcome, and course. The preponderance of depressive symptoms is typical, and the risk of rapid cycling is estimated to be eight times higher for women than for men. Comorbid anxiety and eating disorders occur more frequently in female patients. In planning treatment it is important to take fertility, contraception, and pregnancy into consideration and adjust the pharmacotherapy to harmonize with the patient's current phase of life. Little is known about potential sexual dysfunctions of bipolar women. Further research should include clinical and observational studies focusing on gender-specific differences in symptomatology, treatment, and long-term outcome of bipolar disorders.

Xenogenic oogenesis of chicken (Gallus domesticus) female primordial germ cells in germline chimeric quail (Coturnix japonica) ovary

In present study, chicken primordial germ cells (PGCs) were transferred into quail embryos to investigate the development of these germ cells in quail ovary. Briefly, 2 microl of chicken embryonic blood (stage 14) or about 100 purified circulating PGCs were transferred into quail embryo. Contribution of chicken PGCs were detected in gonads of chimeric quail embryos (stage 28) by immunocytochemical staining of cell surface antigen SSEA-1, and by in situ hybridization (ISH) with female chicken specific DNA probe. As a result, 52.0+/-43.2 (n=18) and 42.7+/-27.3 (n=17) chicken PGCs were found in the gonads of chimeric quail embryo that was injected with chicken embryonic blood (stage 14) and about 100 purified circulating PGCs, respectively. Furthermore, the ovaries of 81.8% (9/11) 12 days post incubation (dpi) chimeric quail embryos were observed with a mean of 457.6+/-237.1 female chicken PGCs-derived oogonia scattered in ovarian cortex area. In 9 out of 12 newly hatched and one week old chimeric quail chicks, on average of 2883.0+/-1924.1 primary oocytes and 3 follicles derived from chicken PGCs were found, respectively. The present results suggest that chicken female PGCs are able to migrate, colonize, proliferate and differentiate into oogonia, primary oocytes in chimeric quail ovary.

A 40-basepair VNTR polymorphism in the dopamine transporter (DAT1) gene and the rapid response to antidepressant treatment

Finding predictors of the response to antidepressant therapy is a major goal of molecular psychiatry. The genes encoding the serotonin (SERT) and dopamine (DAT1) transporters are among the possible candidate genes modulating an individual's antidepressant response. In a naturalistic prospective cohort study with a total of 190 fully assessed patients, improvement of depression symptoms during the 3 weeks following initiation of antidepressant therapy was recorded using the 21-item Hamilton Depression Rating Scale (HDRS). The SLC6A3 3' UTR 40-bp variable number of tandem repeats (VNTR) and the SLC6A4 5' 44-bp insertion/deletion polymorphism were analyzed by polymerase chain reaction. There was a significantly smaller number of rapid responders among homozygous carriers of the DAT1 9-repeat allele (9/9) than among heterozygous (9/10) and homozygous (10/10) carriers of the 10-repeat allele (19 versus 37 versus 52%, respectively, P=0.0037). Median decline in HDRS score was 35, 40, and 52% in patients with the 9/9, 9/10, and 10/10 genotypes, respectively (P=0.013). The effect was found in all classes of medications (selective serotonin reuptake inhibitors (SSRIs), tricyclics, mirtazapine, venlafaxine) and statistically significant also within the subgroup of patients having received SSRIs. The serotonin promoter insertion/deletion genotype had no effect in the entire study group, but there was an insignificant trend of better response in the l/l and l/s carriers who received SSRIs or mirtazapine. In conclusion, the dopamine transporter VNTR polymorphism influenced rapid response to antidepressant therapy. Compared with homozygous carriers of the 10-repeat allele, carriers of the 9/10 genotype had an odds ratio (OR) calculated by logistic regression analysis of 1.6 (95% CI 0.8-3.2) and carriers of the 9/9 genotype had an OR of 6.0 (1.5-24.4) for no or poor response. Further studies are required to confirm this clinical association and to elucidate the underlying mechanisms.

Pharmakogenomik in der klinischen Praxis

The pharmacokinetics and effect of antidepressants are influenced by genetic factors. Modern methods of genotyping allow fast and inexpensive identification of genetic variants and thus can be used in clinical diagnostics to improve the tolerance to drug therapy. Numerous studies have investigated the significance of genetic variants in drug-metabolizing enzymes, drug and natural substrate transporters, neurotransmitter receptors, and molecules involved in signal transduction. While the interindividual differences in oral clearance, half-life, and bioavailability caused by genetic variants in the cytochrome P450 liver enzymes can be overcome by individual adjustment of dosage according to certain genotypes, the effects of genetic variants in antidepressive target structures are more difficult to translate into clinical recommendations. This article gives an overview of the currently available literature and points to situations in which the determination of pharmacogenetic variants might change drug therapy or therapeutic strategies for the individual patient. Dose adjustments for common antidepressant drugs based upon differences in pharmacokinetic parameters caused by genetic variability will be given.

[Bipolar disorders--how to recognize and treat them]

Bipolar disorders are often diagnosed too late with an average of ten years elapsing between the first disease episode and the correct diagnosis and treatment. The most common misdiagnoses are unipolar depression, schizophrenia and ADHD (Attention Deficit Hyperactivity Disorder). The suicide rate associated with bipolar disease is very high. Treatment consists in the administration of mood stabilizers, in the first instance lithium, but also atypical neuroleptics or lamotrigine. In the depressive phase, additional antidepressants or lamotrigine, in the manic phase valproate or an antipsychotic agent may be needed. Medication must be continued unchanged for several months beyond acute treatment. The subsequent relapse prophylaxis depends on effectiveness, tolerability, comorbidity, suicidal risk and compliance. Pharmacotherapy is supplemented by psychotherapy and psycho-education.

Lithium augmentation in treatment-resistant depression: clinical evidence, serotonergic and endocrine mechanisms

For now more than 50 years, lithium has been the gold standard for the pharmacologic treatment of bipolar disorder. However, its utility is not restricted to acute mania and prophylactic treatment of bipolar disorder. A relatively new indication for its use is the addition to an antidepressant in the acute treatment phase of unipolar major depression. To date, this treatment approach called lithium augmentation is the best-documented approach in the treatment of refractory depression. In international treatment guidelines and algorithms, lithium augmentation is considered a first-line treatment strategy for patients with a major depressive episode who do not adequately respond to standard antidepressant treatment. In a recent double-blind, placebo-controlled trial, lithium augmentation has demonstrated to also be effective in the continuation treatment phase to prevent early relapses. From animal studies there is robust evidence that lithium augmentation increases serotonin (5-HT) neurotransmission, possibly by a synergistic action of lithium and the antidepressant on brain 5-HT pathways. In contrast to the established decline of HPA system activity during treatment with tricyclic antidepressants, neuroendocrine studies on the effects of lithium augmentation on the HPA system showed an unexpected and marked increase in the ACTH and cortisol response in the combined DEX/CRH test. Here we review new data on the efficacy and mechanism of action of lithium augmentation.

Evaluation of a newly developed real-time PCR for the detection of Taylorella equigenitalis and discrimination from T. asinigenitalis

A 'culture-LightCycler PCR' assay has been developed for the detection of Taylorella equigenitalis, the causative agent of contagious equine metritis (CEM) in horses. The primers and hybridisation probes were derived from the 16S rDNA sequence. Their specificity was determined in two closely related organisms and six commensal bacteria of the genital tract. The assay was specific for T. equigenitalis and discriminates T. asinigenitalis isolates. It also avoids misidentifications of morphologically and phenotypically similar organisms. The sensitivity was evaluated in comparison to a standard bacteriological culture method. It detected T. equigenitalis in 10 of 52 samples that had not been identified bacteriologically. The results indicated that the assay had a greater sensitivity. This is the first real-time PCR for the detection of T. equigenitalis and avoids PCR carry-over contamination. The 'culture-LightCycler PCR' assay is specific, sensitive and reproducible, and can be used effectively for the detection of T. equigenitalis infections.

[Primary subcutaneous hematogenous osteomyelitis in childhood]

The most frequent form of bone infection is haematogenous osteomyelitis (HOM), typically affecting infants and children. Dependent on the virulence of the pathogen and the patients immune response, one can distinguish between the acute (AHOM) and primary subacute haematogenous osteomyelitis (PSHO). In contrast to AHOM, diagnosis of PSHO is severely impeded in that clinical and blood-chemistry findings usually do not enable differentiation from primary malignant bone tumors. With a comparable age predilection and clinical symptoms, as well as very similar conventional radiographic, MRI- and bone-scan-findings, the most important differential diagnosis is Ewing's-sarcoma. The here demonstrated case of a 12 year-old girl shows that PSHA may imitate a sarcoma very closely, even concerning such usually fairly reliable radiographic aspects like osteolysis and lamellar periostal bone reaction. Despite the use of MRI, the diagnosis initially remained uncertain and a malignant bony lesion could only be ruled out after open biopsy and histopathological evaluation.

Analysis of ploidy (in megabase chromosomes) in Trypanosoma brucei after genetic exchange

The megabase chromosomes of Trypanosoma brucei are normally diploid, but the extent to which this ploidy is maintained when parasites undergo genetic exchange is not known. To investigate this issue, a panel of 30 recombinant clones resulting from the co-transmission through tsetse flies of three different parental T. brucei lines in all pair-wise combinations (STIB 247, STIB 386 and TREU 927/4) were examined. These clones are products of 28 different mating events; four of them result from self-fertilisation and the others are F1 hybrids. DNA contents of the three parental lines were determined by flow cytometry and shown to differ only slightly with DNA content increasing in the order 927/4 < 247 < 386. Flow cytometry of the recombinant clones indicated DNA contents were similar to the parents in 28 clones and raised approximately 1.5 times the parental values in only two. The two F1 hybrid progeny with raised DNA contents were shown by marker analysis to be trisomic for seven independent loci indicating that they were probably triploid whereas progeny with DNA contents similar to parental values inherited a single allele from each parent for four independent loci indicating that they were diploid.

Evidence that FGF receptor signaling is necessary for endoderm-regulated development of precardiac mesoderm

Endoderm cells in the heart forming region (HFR endoderm) of stage 6 chicken embryos are required to support the proliferation and terminal differentiation of precardiac mesoderm cells in vitro. The endoderm's effect can be substituted by growth factors, including members of the fibroblast growth factor (FGF) family. However, direct implication of FGFs in this process requires evidence that inhibition of FGF signaling interferes with proliferation and/or terminal differentiation. This report examines the consequences of treating endoderm/precardiac mesoderm co-explants with agents that inactivate FGF receptors. Using sodium chlorate, which prevents FGF ligand-receptor interaction, it was observed that the percentage of S-phase precardiac mesoderm cells was markedly reduced, suggesting that cell proliferation was inhibited. To more specifically affect FGF signaling, the explants were treated with an antibody that recognizes an extracellular domain of FGF receptor-1 (FGFR-1). This treatment similarly inhibited cell proliferation. Although both agents modestly delayed cardiac myocyte differentiation as indicated by the contractile function, expression of alpha-sarcomeric actin was not affected. These findings provide additional evidence that an intact FGF signaling pathway is required during heart development.

Regulation of new blood vessel growth into ischemic skeletal muscle

PURPOSE

In a rabbit model, transposition of a muscle pedicle flap to an ischemic hind limb has been shown to result in the development of new blood vessels that connect the arterial circulation of the flap to the circulation of the limb. The hypothesis that exogenous recombinant basic fibroblast growth factor (bFGF) would enhance the development of this new blood supply was examined and the regulation of bFGF in this process was investigated.

METHODS

The right common iliac artery was ligated in 12 male New Zealand white rabbits. An abdominal wall muscle flap based on the left inferior epigastric artery was transposed to the right thigh. bFGF in phosphate-buffered saline (PBS) at 3 ng/h (n = 6), or PBS alone (n = 6), was infused for 7 days via mini-osmotic pumps with an infusion catheter positioned at the flap-muscle interface. The flap-muscle interface was immunostained with anti-alpha-actin antibody to determine blood vessel density (number of vessels/mm) and with anti-bFGF antibody to evaluate bFGF distribution. RNA was isolated from these sections, and polymerase chain reaction (PCR) was used to examine endogenous bFGF messenger RNA (mRNA) expression.

RESULTS

Blood vessel density was significantly increased in animals receiving exogenous bFGF (22. 0 +/- 10.6 vessels/mm vs. 10.7 +/- 8.8 vessels/mm, P =.009). In the controls, neovessels were arranged in clusters with endogenous bFGF concentrated around these clusters. In bFGF-treated animals, vessels were diffusely scattered throughout the flap-limb interface, corresponding to the distribution pattern of infused bFGF. There was no difference in bFGF mRNA expression between the control and the bFGF-treated groups.

CONCLUSION

Exogenous bFGF infusion significantly augmented new blood vessel development at the flap-limb interface. Endogenous bFGF was up-regulated around the newly developed microvessels in control animals, and vessel growth correlated with the diffuse distribution of exogenous bFGF, implicating bFGF as an important factor in angiogenesis. Exogenous bFGF did not affect bFGF mRNA expression, suggesting that the regulation of bFGF is not under autocrine control.

Mutational analysis of acute-phase response factor/Stat3 activation and dimerization

Signal transducer and transcription (STAT) factors are activated by tyrosine phosphorylation in response to a variety of cytokines, growth factors, and hormones. Tyrosine phosphorylation triggers dimerization and nuclear translocation of these transcription factors. In this study, the functional role of carboxy-terminal portions of the STAT family member acute-phase response factor/Stat3 in activation, dimerization, and transactivating potential was analyzed. We demonstrate that truncation of 55 carboxy-terminal amino acids causes constitutive activation of Stat3 in COS-7 cells, as is known for the Stat3 isoform Stat3beta. By the use of deletion and point mutants, it is shown that both carboxy- and amino-terminal portions of Stat3 are involved in this phenomenon. Dimerization of Stat3 was blocked by point mutations affecting residues both in the vicinity of the tyrosine phosphorylation site (Y705) and more distant from this site, suggesting that multiple interactions are involved in dimer formation. Furthermore, by reporter gene assays we demonstrate that carboxy-terminally truncated Stat3 proteins are incapable of transactivating an interleukin-6-responsive promoter in COS-7 cells. In HepG2 hepatoma cells, however, these truncated Stat3 forms transmit signals from the interleukin-6 signal transducer gp130 equally well as does full-length Stat3. We conclude that, dependent on the cell type, different mechanisms allow Stat3 to regulate target gene transcription either with or without involvement of its putative carboxy-terminal transactivation domain.

Evidence that fibroblast growth factors 1 and 4 participate in regulation of cardiogenesis

Previous studies in this laboratory have indicated that the early embryonic chick heart depends on fibroblast growth factor-2 (FGF-2; bFGF), sequentially utilized in paracrine and autocrine fashion, for its growth and development (Sugi and Lough, [1995] Dev. Biol. 168-567-574). This view emanated from immunohistochemical detection of FGF-like antigens in endoderm cells at stage 6, and later in the early myocardium at stage 9+ (Parlow et al. [1991] Dev. Biol. 146:139-147). To identify other members of the FGF family that are expressed by these cells, we have used peptide-generated antisera that specifically recognize FGFs 1 and 4. Like FGF-2, FGFs 1 and 4 were exclusively detected in the endoderm at stage 5+ and later in the myocardium, appearing as punctate cytoplasmic deposits. However, whereas FGF-2 is first detected at stage 9+, FGFs 1 and 4 did not appear until stages 11 and 15, respectively. Expression of all FGFs peaked at stages 18-24, decreasing thereafter in parallel with reduced myocardial cell proliferation. To determine these isoproteins' ability to facilitate the completion of terminal cardiac myocyte differentiation, stage 5+ precardiac mesoderm was cultured in defined medium with purified FGFs. Like FGF-2, as little as 5-10 ng/ml FGF-1 or FGF-4 supported the proliferation and differentiation of precardiac myoblasts, resulting in the formation of a vesicle containing an adherent multilayer of synchronously contractile cells. Evidence that this represented FGF receptor-mediated signaling rather than a nonspecific effect of exogenous FGF was indicated by the ability of sodium chlorate to inhibit FGF-mediated cardiogenesis. These findings are consistent with the hypothesis that, like FGF-2, FGFs 1 and 4 participate in the regulation of early heart development via paracrine and autocrine mechanisms.

Differential activation of acute phase response factor/Stat3 and Stat1 via the cytoplasmic domain of the interleukin 6 signal transducer gp130. II. Src homology SH2 domains define the specificity of stat factor activation

Distinct yet overlapping sets of STAT transcription factors are activated by different cytokines. One example is the differential activation of acute phase response factor (APRF, also called Stat3) and Stat1 by interleukin 6 and interferon-gamma. Interleukin 6 activates both factors while, at least in human cells, interferon-gamma recruits only Stat1. Stat1 activation by interferon-gamma is mediated through a cytosolic tyrosine motif, Y440, of the interferon-gamma receptor. In an accompanying paper (Gerhartz, C., Heesel, B., Sasse, J., Hemmann, U., Landgraf, C., Schneider-Mergener, J., Horn, F., Heinrich, P. C., and Graeve, L. (1996) J. Biol. Chem. 271, 12991-12998), we demonstrated that two tyrosine motifs within the cytoplasmic part of the interleukin 6 signal transducer gp130 specifically mediate APRF activation while two others can recruit both APRF and Stat1. By expressing a series of Stat1/APRF domain swap mutants in COS-7 cells, we now determined which domains of Stat1 and APRF are involved in the specific recognition of phosphotyrosine motifs. Our data demonstrate that the SH2 domain is the sole determinant of specific STAT factor recruitment. Furthermore, the SH2 domain of Stat1 is able to recognize two unrelated types of phosphotyrosine motifs, one represented by the interferon-gamma receptor Y440DKPH peptide, and the other by two gp130 YXPQ motifs. By molecular modeling, we propose three-dimensional model structures of the Stat1 and APRF SH2 domains which allow us to explain the different binding preferences of these factors and to predict amino acids crucial for specific peptide recognition.

Differential activation of acute phase response factor/STAT3 and STAT1 via the cytoplasmic domain of the interleukin 6 signal transducer gp130. I. Definition of a novel phosphotyrosine motif mediating STAT1 activation

Interleukin-6 (IL-6) and gamma-interferon (IFNgamma) activate an overlapping set of genes via the Jak/STAT pathway. However, at least in human cells, a differential activation of STAT transcription factors was observed: IL-6 activates both acute phase response factor (APRF)/STAT3 and STAT1, whereas IFNgamma leads only to STAT1 activation. All STATs cloned so far contain SH2 domains. Since all cytokine receptors using the Jak/STAT pathway were found to be tyrosine-phosphorylated after ligand binding, it has been proposed that specific phosphotyrosine modules within the cytoplasmic domain of the receptor chains recruit different STAT factors. We have analyzed by mutational studies and by phosphopeptide competition assays which of the tyrosine modules of the IL-6 signal transducer gp130 are capable of recruiting either APRF or STAT1. We found that two of the four tyrosine modules that are important for APRF activation also activate STAT1. For these modules, we propose the new consensus sequence YXPQ. We further present evidence that STAT1 is activated independently from APRF suggesting that gp130 contains multiple independent STAT binding sites. We compare the APRF and STAT1 activation motifs of gp130 with the STAT1 activation motif of the IFNgamma receptor and demonstrate that the specificity of activation can be changed from APRF to STAT1 and vice versa by only two point mutations within a tyrosine module. These data strongly support the concept that the activation of a specific STAT is determined mainly by the phosphotyrosine module. The significance of these findings for other receptor systems is discussed.

Human high affinity, Na(+)-dependent L-glutamate/L-aspartate transporter GLAST-1 (EAAT-1): gene structure and localization to chromosome 5p11-p12

The gene of the human L-glutamate transporter hGLAST-1 (EAAT-1) has been isolated and characterized. The 1626 bp cDNA open reading frame (542 aa) is distributed over ten exons and at least 85 kb on chromosome 5p11-p12. The gene is unrelated to any other previously described neurotransmitter transporter gene family, but its exon/intron structure corresponds largely to that of the Na(+)-dependent neutral amino acid transporter ASCT-1. GLAST-1, ASCT-1 and the glutamate transporters GLT-1 and EAAC-1 have strongly similar amino acid sequences. The L-glutamate transporter gene structures might help to understand the correlation of L-glutamate reuptake in neurodegenerative disorders.

Role of basic fibroblast growth factor in prostatic tumors

Compared with normal prostatic tissue, the level of basic fibroblast growth factor (bFGF) is elevated in prostatic tumors. This suggests that bFGF may play a role in the development of prostatic neoplasms. The current study was undertaken to identify the cellular distribution of bFGF in benign prostatic hyperplasia (BPH) and prostatic carcinoma using a polyclonal antiserum against recombinant bFGF. In paraffin sections of prostatic tumors immunoreactive bFGF was found in fibroblasts, smooth muscle cells, and endothelial cells. Distinct staining was seen in most nuclei of these cells and a less intense immunoreaction occurred in the cytoplasm of smooth muscle cells. No immunostaining was seen in prostatic epithelial cells of prostatic tumors whether benign or malignant. With digoxigenin-labeled oligonucleotides in nonradioactive in situ hybridization, the presence of mRNA for bFGF was shown in smooth muscle cells of the stroma, suggesting that these cells are the main source of bFGF in BPH. Because no immunostaining for bFGF was obtained in the carcinoma cells, a specific role for bFGF cannot be seen for the development of malignant prostatic tumors.

Basement membrane composition of cartilage canals during development and ossification of the epiphysis

BACKGROUND

Cartilage canals are perichondral invaginations of blood vessels and connective tissue that are found within the epiphyses of most mammalian long bones. Functionally, they provide a means of transport of nutrients to the hyaline cartilage, a mechanism for removal of metabolic wastes, and a conduit for stem cells that are capable of initiating and sustaining ossification of the chondroepiphysis. Morphological and biomolecular changes of the chondroepiphyses appear to potentiate ossification within the chondroepiphyses of developing bones.

METHODS

As both cell migration and vascular invasion are anchorage dependent processes, antibodies to laminin and Type IV collagen were used to assess compositional changes in the basement membrane of cartilage canals accompanying epiphyseal ossification.

RESULTS

Differences in chronological appearance, as well as, in distribution between the two components were noted in the chondroepiphysis. Laminin was distributed throughout the connective tissue of cartilage canal at all stages of development, and not limited to an association with the vascular lumen. Type IV collagen was not present during the initial perichondral invagination. Although staining for Type IV collagen was later acquired, its distribution was restricted to a discontinuous rimming of the periphery of the canal, and a diffuse presence within the intra-canalicular mesenchyme.

CONCLUSIONS

Concurrent with chondrocyte hypertrophy and mineralization of the hyaline matrix, rapid changes in both the morphology of the vessel and distribution of the antibodies were detected. In addition to the presence of laminin at the interface of the endothelium and the hyaline matrix, a wide distribution within the connective tissue components of the newly ossifying matrix of epiphyseal bone could be detected. Type IV collagen remained closely associated with the lumens of the intra-canalicular vessels throughout the transition. Following ossification of the secondary center, staining for Type IV collagen could then be detected in the bone-forming regions of transforming matrix as well, clearly delineating the individual vessels within the newly formed marrow spaces. This suggests that bone formation is intimately related to vessel staining for collagen type IV, and that acquired vessel competence is a facet of endochondral bone formation that results from provisional matrix changes. Furthermore, the data suggests that during bone formation under tension, basement membrane deposition can be demonstrated without an intermediary hyaline matrix hypertrophic chondrocyte phase. This data was interpreted to suggest that chondrocyte hypertrophy at the growth plate may be a reaction to vascular invasion, that in turn, stimulates adjacent chondrocyte proliferation.

Developmental expression of fibroblast growth factor receptor-1 (cek-1; flg) during heart development

Previous work in this laboratory has indicated that fibroblast growth factor-2 (FGF-2; bFGF) regulates the initial stages of avian heart development in paracrine and autocrine fashion (Parlow et al. [1991] Dev. Biol. 146:139-147; Sugi et al. [1993] Dev. Biol. 157:28-37). Because these findings inferred the presence of a functional receptor for fibroblast growth factor (FGFR), we have immunochemically assessed the appearance of FGFR-1 (cek-1; flg) during development. Using a peptide-generated antibody, Western blots of total embryonic proteins revealed that FGFR-1 was barely detectable at pre-heart stages, followed by sequential increases in relative abundance that peaked at stage 24, followed by a decline at days 7-14. Western blots of proteins from isolated embryonic hearts demonstrated a similar developmental pattern, except that FGFR-1 expression was not decreased at later stages. The presence of FGFR-1 mRNA was verified by reverse transcription/polymerase chain reaction (RT/PCR) amplification. Immunohistochemical examination revealed punctate deposits of FGFR-1 in the precardiac endoderm at stage 6, followed by detection in the endoderm, foregut, and pre-cardiac splanchnic mesoderm at stage 8 and in the newly formed myocardium at the heart tube stage (9/10). By stage 13, FGFR-1 staining was observed only in the myocardium, a pattern which persisted at least until stage 30 (day 7), after which only isolated hearts were examined. After stage 30, staining was diminished in the ventricle, but not in the atrium. Staining of cardiac endothelial cells was not observed at any stage. A functional role for FGFR-1 was indicated by experiments in which anti-FGFR-1, but not pre-absorbed antiserum, retarded proliferation and multilayering of cardiogenic cells in an in vitro model of cardiac morphogenesis.

Assessment of bone formation during osteoneogenesis: a canine model

Distraction osteoneogenesis, callotasis, has been demonstrated to be an effective means of lengthening long bones. A variation of Ilizarov's technique produces a transport disk from one cut surface of bone within a defect and advances the disk to the opposite surface to close the defect. This process, previously described by Costantino et al. (Arch Otolaryngol Head Neck Surg 1990; 116:535-45), demonstrated bone formation within the distraction site. The precise mechanism of bone formation has not yet been described for the mandible. Four conditioned beagles were studied, with one control dog maintained in neutral fixation and three dogs distracted at 0.25 mm every 8 hours. A two-cm defect was closed, and dogs were kept in fixation for 1 week after closure, after which they were killed. Three sites were evaluated: (1) the distraction seam, (2) the interface of the cortical and distracted bone, and (3) the cortexes at the closed defect. Each site was bisected, and one half was decalcified for immunohistochemical and hematoxylin and eosin pathologic evaluation. The vascular basement membrane was labeled for laminin and type IV collagen. Both of these substances demonstrate the differentiation of the vascular matrix component predisposing primary bone formation. Labels were intense at the distraction seam where intense angiogenesis occurred. No hyalin cartilage was observed at the distraction site, which indicates that the fixation was stable and that ossification occurred primarily without intermediate callous formation. This model demonstrated that osteoclasts within the canine model produce bone through primary bone formation within an angiogenic matrix rich in basement membrane laminin and type IV collagen. Likewise, bone is species specific in mineral composition for dog mandible. Understanding the formation and composition of distracted bone is essential for understanding application of this technique within the clinical setting.

Assessment of Bone Formation during Osteoneogenesis: A Canine Model

Distraction osteoneogenesis, callotasis, has been demonstrated to be an effective means of lengthening long bones. A variation of Ilizarov's technique produces a transport disk from one cut surface of bone within a defect and advances the disk to the opposite surface to close the defect. This process, previously described by Costantino et al. (Arch Otolaryngol Head Neck Surg 1990; 116:535–45), demonstrated bone formation within the distraction site. The precise mechanism of bone formation has not yet been described for the mandible. Four conditioned beagles were studied, with one control dog maintained in neutral fixation and three dogs distracted at 0.25 mm every 8 hours. A two-cm defect was closed, and dogs were kept in fixation for 1 week after closure, after which they were killed. Three sites were evaluated: (1) the distraction seam, (2) the interface of the cortical and distracted bone, and (3) the cortexes at the closed defect. Each site was bisected, and one half was decalcified for immunohistochemical and hematoxylin and eosin pathologic evaluation. The vascular basement membrane was labeled for laminin and type IV collagen. Both of these substances demonstrate the differentiation of the vascular matrix component predisposing primary bone formation. Labels were intense at the distraction seam where intense angiogenesis occurred. No hyalin cartilage was observed at the distraction site, which indicates that the fixation was stable and that ossification occurred primarily without intermediate callous formation. This model demonstrated that osteoclasts within the canine model produce bone through primary bone formation within an angiogenic matrix rich in basement membrane laminin and type IV collagen. Likewise, bone is species specific in mineral composition for dog mandible. Understanding the formation and composition of distracted bone is essential for understanding application of this technique within the clinical setting.

Evaluation of distraction osteogenesis by scanning electron microscopy

A model of bifocal distraction osteogenesis in the canine model was used to assess and quantitate the mineral content of the newly forming bone within the canine mandible. A 2-cm defect was created in the body of the mandible, and after a posterior osteotomy, the transport disk was advanced at 0.25 mm per 8 hours for 21 days and then held in rigid fixation for an additional week. As a control for this study, three additional dogs underwent the same procedure with the exception that the transport disk was not advanced. Electron dispersive spectroscopy analysis was performed on the newly formed regenerate bone and compared with areas of existing cortical bone of both the transport disk and the mandible. In the control model, special note was made of the pericortical callus at the osteotomy site as well as of the regenerative bone that filled the 2-cm defect in the body of the mandible. Calcium/phosphorous ratios were used to assess the composition of the mineralized regions of the mandible. The regenerate bone that filled the defect and the mineralized callus surrounding the site of osteoclasis in the control mandible were significantly different in composition when compared with the regenerate bone that formed during distraction osteogenesis. This suggests that distraction osteogenesis may effect an initial matrix production that is more similar in composition to the mature cortical bone from which it was derived than does periosteal regeneration and filling of an osseous defect.

Length variation in the keratan sulfate domain of mammalian aggrecan

The keratan sulfate domain of aggrecan consists of a series of tandemly repeating hexapeptides which have the consensus sequence Glu-Glu/Lys-Pro-Phe-Pro-Ser, where the serine side-chains presumably provide sites for the attachment of keratan sulfate (KS) chains. The number of hexapeptide repeats varies between species, ranging from four in rat (Doege et al., 1987) and mouse (Walcz et al., 1992) to 13 in human (Doege et al., 1991) and 23 in bovine aggrecan (Antonsson et al., 1989). Chicken aggrecan (Chandrasekaran and Tanzer, 1992) does not contain a KS domain with a recognizable hexapeptide motif. The extent of this variation among mammalian and avian species is not known, and there is currently no explanation to predict how differences in the size of the KS domain would affect aggrecan function. We used polymerase chain reaction (PCR) to amplify the portion of the human, canine and porcine aggrecan gene that codes for the KS domain. We sequenced the amplified products in each case. Human aggrecan, with 13 hexapeptide repeats (Doege et al., 1987), was used as reference and found to be essentially identical to published data. The canine and porcine KS domains consisted of six and ten hexapeptide repeats respectively. The same PCR protocol was used to amplify the KS domain from genomic DNA of eight other mammalian species. Comparison of the size of these amplified products, as determined by agarose gel electrophoresis, with those for which sequence data are available allowed us to estimate the number of repeats in the KS domain. In almost half the species examined, the KS domain consisted of 13 hexapeptide repeats.

Basement membrane of blood vessels during distraction osteogenesis

A canine model of distraction osteogenesis has recently been developed that permitted the evaluation of bone formation and its vascularization during bifocal callotasis. In this model, the authors examined the composition of the blood vessels during distraction osteogenesis of the mandible for laminin and for Type IV collagen, both constituents of the vascular basement membrane. At the fibrous distraction site, at the juncture of the free cortical surface and the regenerated bone, and at the abutting cortical surfaces at the distal margin of the defect, laminin and Type IV collagen were present in all vessels.

Expression and subcellular distribution of basic fibroblast growth factor are regulated during migration of endothelial cells

Migration of endothelial cells is involved in normal and pathological angiogenesis and in re-endothelialization after vascular injury or rupture of atherosclerotic plaques. Several types of endothelial cells are known to synthesize basic fibroblast growth factor (bFGF); in some of these, migration is increased by exogenous bFGF and inhibited by anti-bFGF antibodies. Using immunocytochemical techniques and RNase protection analysis, we studied endothelial cells from bovine coronary arteries and veins as well as from adrenal microvessels. We found that bFGF mRNA and peptide were present in confluent endothelial cells and were upregulated during migration stimulated by removal of some cells from the monolayer. During migration, extracellular matrix stores of bFGF were depleted, and bFGF immunoreactivity began to accumulate in the cytoplasm of endothelial cells between 2 and 6 hours. After migration had begun, but before the initiation of DNA synthesis, bFGF immunoreactivity increased in the nuclei and nucleoli. Exogenous bFGF stimulated endothelial migration, and antibodies to bFGF markedly inhibited migration, suggesting that an intracrine function of nuclear bFGF is not sufficient for cell migration. In all three types of endothelial cells studied, bFGF was identified as an endogenous regulator, but not as the sole regulator, or migration. Moreover, bFGF expression and subcellular localization were found to be regulated during endothelial cell migration.

Distribution of FGF-2 suggests it has a role in chick limb bud growth

We developed and characterized antibodies specific for FGF-2 and used them to locate FGF-2 during chick embryo development. A series of micrographs demonstrated the progression of FGF-2 staining during development of the different tissues and organs. FGF-2 was present in the ectoderm covering the entire embryo, muscle cells, nervous system, neural crest cells, and mesonephros. FGF-2 was also present in the limb from initiation of budding through differentiation. The limb ectoderm and subjacent mesoderm showed the strongest immunostaining, with lower levels in the center of the bud. However, the distribution of FGF-2 positive cells in the mesoderm was not homogeneous. This heterogeneity was not due to cell cycle specific distribution of FGF-2 protein, as flow cytometric analysis showed that FGF-2-positive cells were distributed throughout the cell cycle. However, the amount of anti-FGF-2 fluorescence varied most during G1, consistent with the possibility that FGF-2 is low after M phase and increases during G1. A bioassay was used to demonstrate FGF-2 levels in the wing ectoderm were approximately 2.7-fold greater than in the mesoderm. We propose that the location of FGF-2 in the embryo is consistent with a role in epithelial-mesenchymal interactions; in the limb bud it may prevent differentiation and permit limb outgrowth and subsequent expression of patterning events.

Pleiotrophin is an abundant protein in dissociative extracts of bovine fetal epiphyseal cartilage and nasal cartilage from newborns

An abundant protein that is identical to the growth-associated protein pleiotrophin (PTN) has been isolated from dissociative extracts of bovine nasal and fetal epiphyseal cartilage. The yield from these tissues was at least 15 micrograms/g wet weight of cartilage. PTN was absent or was present only in trace amounts in mature articular cartilage. An analysis of tryptic fragments of PTN, held together with disulfide bonds, did not indicate any set pattern of cystine cross-links, which suggests a propensity for rapid refolding of the protein. PTN could not be isolated from thin (10 microns) slices of nasal cartilage in physiological extraction buffers, which indicates that it was tightly associated with the cell surface, was tightly associated with nonextractable matrix, or was an intracellular protein. Its appearance in various extraction media parallels that of histone H2b, a nucleosomal protein; this suggests a possible intracellular location for the protein. Immunohistochemical analysis of its distribution in fetal epiphysis indicated that it is associated with chondrocytes.

Inhibition of precardiac mesoderm cell proliferation by antisense oligodeoxynucleotide complementary to fibroblast growth factor-2 (FGF-2)

This laboratory recently reported the occurrence of concentrated deposits of fibroblast growth factor-2 (FGF-2; basic FGF)-like proteins in the sarcoplasm of embryonic cardiac myocytes from the earliest stage of avian heart development (M. H. Parlow, D. L. Bolender, N. P. Kokan-Moore, and J. Lough, Dev. Biol. 146, 139, 1991). To determine the role, if any, of FGF-2 during embryonic cardiogenesis, the proliferative and functional effects of treating cultured anterior lateral plate mesoderm from Hamburger-Hamilton stage 6 embryos with antisense oligodeoxynucleotide (ODN) complementary to FGF-2 mRNA were determined. Within 2 days of culture in defined medium, the explanted monolayer normally differentiates into a multilayer of proliferative cells that express sarcomeric alpha-actin and exhibit rhythmic contractions. The inclusion of 25 microM ODN that is complementary to the second exon of chicken FGF-2 mRNA caused a 50% inhibition in these cells' proliferative ability as judged by incorporation of 5'-bromodeoxyuridine; contractility was similarly inhibited. These effects were prevented by including recombinant human FGF-2 protein in the medium. Treatment with sense ODN did not cause inhibition. Inhibition of FGF-2 protein synthesis in the explanted tissue by antisense ODN was verified by immunoprecipitation analysis. These results point to a critical role for FGF-2 in the autocrine regulation of proliferation, and perhaps differentiative function, of embryonic cardiac myocytes.

Localization of basic fibroblast growth factor in bovine endothelial cells: immunohistochemical and biochemical studies

To gain insight into the mechanisms of synthesis, storage, and release of basic fibroblast growth factor (bFGF), we studied the immunohistochemical localization of bFGF in bovine coronary artery, coronary sinus, and adrenal capillary endothelial cells grown in culture. Light and electron microscopic immunohistochemical studies were performed using the ABC immunoperoxidase method on p-formaldehyde-fixed cells. Five different anti-bFGF antibodies gave similar results in all cell types. In subconfluent cells, immunoreactivity was noted in the nuclear chromatin, nucleoli, cytosol, cytoplasmic vesicles (some of which appeared to fuse with the plasma membrane), and extracellular matrix. No reaction was found in endoplasmic reticulum or Golgi zones. Confluent cells demonstrated less immunoreactivity in the nuclei and cytosol but more in the extracellular matrix. Some cells of senescent morphology showed only cytoplasmic staining; however, no cells were found with only nuclear staining. Biochemical studies showed that three forms of bFGF (18, 24, and 26 kDa) were present in endothelial cells and varied with different culture conditions. Protection analysis indicated that bFGF mRNA is less abundant in postconfluent cells than in subconfluent cells. These data suggest that subconfluent cells synthesize bFGF and transport it into the nucleus and exocytotic vesicles, while confluent cells synthesize little bFGF but store it in extracellular matrix, cytoplasmic vesicles, and nuclei.

Differential regulation of biglycan and decorin by retinoic acid in bovine chondrocytes

The small, leucine-rich proteoglycans, decorin and biglycan, are prominent components of many extracellular matrices and are differentially regulated in various tissues. We have examined the effects of retinoic acid (RA) on the expression of biglycan and decorin at the protein and mRNA levels in cultured bovine articular chondrocytes. Biglycan protein expression is rapidly turned off after 1-2 days of treatment with RA. In contrast, decorin protein expression is increased 12-18-fold following 3 days of RA treatment. The level of biglycan mRNA was also rapidly reduced upon RA treatment, mirroring the protein expression. The reduction was apparent by 6 h, and, by 4 days, the levels were nearly undetectable. In contrast, decorin mRNA was induced upon treatment with RA. The increase in decorin message levels was first apparent by 24 h, reaching maximum by 2 days, and remained constant through 4 days. The repression of biglycan mRNA displayed equal sensitivity to RA concentrations from 10(-5) to 10(-9) M. Decorin mRNA was induced in a dose-dependent fashion by RA. Retinoic acid at a concentration of 10(-5) M, the highest dose examined, resulted in maximal induction of the message, and control levels were obtained with 10(-8) M. The protein synthesis inhibitor cycloheximide inhibited the induction of decorin mRNA, indicating that the induction by RA was a secondary event. In contrast, the repression of biglycan by RA was not significantly altered by cycloheximide, showing that the repression was a direct effect. Actinomycin D inhibited the induction of decorin mRNA, indicating that transcription was required for the induction. Nuclear run-on assays confirmed that RA was regulating biglycan mRNA expression at the transcription level. A 24-h RA treatment decreased the level of transcription of the biglycan gene 5-fold. In contrast, no increase in transcription from the decorin gene could be detected by nuclear run-on assays. Therefore, the elevation in decorin mRNA levels observed after RA treatment was the result of a post-transcriptional event, most likely the consequence of stabilization of the message. This study demonstrates that the genes for these two similar proteoglycans are under very different forms of regulation by RA in chondrocytes. The pattern of differential expression of biglycan and decorin could serve as an additional marker for indicating changes of the cartilage phenotype.