Hospital volume following major surgery for gastric cancer determines in-hospital mortality rate and failure to rescue: a nation-wide study based on German billing data (2009-2017).

BACKGROUND: For many cancer resections, a hospital volume-outcome relationship exists. The data regarding gastric cancer resection-especially in the western hemisphere-are ambiguous. This study analyzes the impact of gastric cancer surgery caseload per hospital on postoperative mortality and failure to rescue in Germany. METHODS: All patients diagnosed with gastric cancer from 2009 to 2017 who underwent gastric resection were identified from nation-wide administrative data. Hospitals were grouped into five equal caseload quintiles (I-V in ascending caseload order). Postoperative deaths and failure to rescue were determined. RESULTS: Forty-six thousand one hundred eighty-seven patients were identified. There was a significant shift from partial resections in low-volume hospitals to more extended resections in high-volume centers. The overall in-house mortality rate was 6.2%. The crude in-hospital mortality rate ranged from 7.9% in quintile I to 4.4% in quintile V, with a significant trend between volume categories (p < 0.001). In the multivariable logistic regression analysis, quintile V hospitals (average of 29 interventions/year) had a risk-adjusted odds ratio of 0.50 (95% CI 0.39-0.65), compared to the baseline in-house mortality rate in quintile I (on average 1.5 interventions/year) (p < 0.001). In an analysis only evaluating hospitals with more than 30 resections per year mortality dropped below 4%. The overall postoperative complication rate was comparable between different volume quintiles, but failure to rescue (FtR) decreased significantly with increasing caseload. CONCLUSION: Patients who had gastric cancer surgery in hospitals with higher volume had better outcomes and a reduced failure to rescue rates for severe complications.

Nationwide in-hospital mortality rate following rectal resection for rectal cancer according to annual hospital volume in Germany.

BACKGROUND: The impact of hospital volume after rectal cancer surgery is seldom investigated. This study aimed to analyse the impact of annual rectal cancer surgery cases per hospital on postoperative mortality and failure to rescue. METHODS: All patients diagnosed with rectal cancer and who had a rectal resection procedure code from 2012 to 2015 were identified from nationwide administrative hospital data. Hospitals were grouped into five quintiles according to caseload. The absolute number of patients, postoperative deaths and failure to rescue (defined as in-hospital mortality after a documented postoperative complication) for severe postoperative complications were determined. RESULTS: Some 64 349 patients were identified. The overall in-house mortality rate was 3·9 per cent. The crude in-hospital mortality rate ranged from 5·3 per cent in very low-volume hospitals to 2·6 per cent in very high-volume centres, with a distinct trend between volume categories (P < 0·001). In multivariable logistic regression analysis using hospital volume as random effect, very high-volume hospitals (53 interventions/year) had a risk-adjusted odds ratio of 0·58 (95 per cent c.i. 0·47 to 0·73), compared with the baseline in-house mortality rate in very low-volume hospitals (6 interventions per year) (P < 0·001). The overall postoperative complication rate was comparable between different volume quintiles, but failure to rescue decreased significantly with increasing caseload (15·6 per cent after pulmonary embolism in the highest volume quintile versus 38 per cent in the lowest quintile; P = 0·010). CONCLUSION: Patients who had rectal cancer surgery in high-volume hospitals showed better outcomes and reduced failure to rescue rates for severe complications than those treated in low-volume hospitals.

ANTECEDENTES: El impacto del volumen hospitalario en los resultados de la cirugía del cáncer de recto ha sido poco investigado. Este estudio tuvo como objetivo analizar el impacto de los casos anuales de cirugía de cáncer de recto por hospital en la mortalidad postoperatoria (postoperative mortality, POM) y el fracaso en el rescate (failure to rescue, FtR). MÉTODOS: Todos los casos de pacientes hospitalizados con un diagnóstico de cáncer de recto y un código de procedimiento de resección rectal, tratados de 2012 a 2015, se identificaron a partir de datos hospitalarios administrativos a nivel nacional. Los hospitales se agruparon en cinco quintiles según el volumen de casos. Se determinó el número absoluto de pacientes, la POM y el FtR por complicaciones postoperatorias graves. El FtR se definió como la mortalidad hospitalaria después de una complicación postoperatoria documentada. RESULTADOS: Se identificaron 64.349 casos entre 2012 y 2015. La tasa de mortalidad hospitalaria global fue del 3,89% (n = 2.506). Las tasas brutas de mortalidad hospitalaria variaron de 5,34% (n = 687) en hospitales de muy bajo volumen a 2,63% (n = 337) en centros de muy alto volumen, con una tendencia distinta entre las categorías de centros (P < 0,001). En el análisis de regresión logística multivariante utilizando el volumen hospitalario como efecto aleatorio, los hospitales de muy alto volumen (53 intervenciones/año) tenían una razón de oportunidades (odds ratio, OR) ajustada por riesgo de 0,58 (i.c. del 95%: 0,47-0,73) en comparación con la tasa basal de mortalidad hospitalaria en hospitales de muy bajo volumen (6 intervenciones/año) (P < 0,001). La tasa global de complicaciones postoperatorias fue comparable entre los diferentes quintiles de volumen, pero el FtR disminuyó significativamente con el aumento del volumen de casos (15,63% FtR tras una embolia pulmonar en el quintil más alto versus 38,4% en el hospital del quintil más bajo, P = 0,01). CONCLUSIÓN: Los pacientes sometidos a cirugía de cáncer de recto en hospitales de gran volumen presentaron mejores resultados y una disminución de las tasas de fracaso en el rescate por complicaciones graves en comparación con los pacientes tratados en hospitales de bajo volumen.

Nationwide in-hospital mortality following colonic cancer resection according to hospital volume in Germany.

Background: Colonic cancer is the most common cancer of the gastrointestinal tract. The aim of this study was to determine mortality rates following colonic cancer resection and the effect of hospital caseload on in-hospital mortality in Germany. Methods: Patients admitted with a diagnosis of colonic cancer undergoing colonic resection from 2012 to 2015 were identified from a nationwide registry using procedure codes. The outcome measure was in-hospital mortality. Hospitals were ranked according to their caseload for colonic cancer resection, and patients were categorized into five subgroups on the basis of hospital volume. Results: Some 129 196 colonic cancer resections were reviewed. The overall in-house mortality rate was 5·8 per cent, ranging from 6·9 per cent (1775 of 25 657 patients) in very low-volume hospitals to 4·8 per cent (1239 of 25 825) in very high-volume centres (P < 0·001). In multivariable logistic regression analysis the risk-adjusted odds ratio for in-house mortality was 0·75 (95 per cent c.i. 0·66 to 0·84) in very high-volume hospitals performing a mean of 85·0 interventions per year, compared with that in very low-volume hospitals performing a mean of only 12·7 interventions annually, after adjustment for sex, age, co-morbidity, emergency procedures, prolonged mechanical ventilation and transfusion. Conclusion: In Germany, patients undergoing colonic cancer resections in high-volume hospitals had with improved outcomes compared with patients treated in low-volume hospitals.

Does self-regulation and autonomic regulation have an influence on survival in breast and colon carcinoma patients? results of a prospective outcome study.

BACKGROUND: Cancer Related Fatigue (CRF) and circadian rhythm have a great impact on the quality of life (HRQL) of patients with breast (BC) and colon cancer (CRC). Other patient related outcomes in oncology are measured by new instruments focusing on adaptive characteristics such as sense of coherence or self-regulation, which could be more appropriate as a prognostic tool than classical HRQL. The aim of this study was to assess the association of autonomic regulation (aR) and self-regulation (SR) with survival. METHODS: 146 cancer patients and 120 healthy controls took part in an initial evaluation in 2000/2001. At a median follow up of 5.9 years later, 62 of 95 BC, 17 of 51 CRC patients, and 85 of 117 healthy controls took part in the follow-up study. 41 participants had died. For the follow-up evaluation, participants were requested to complete the standardized aR and SR questionnaires. RESULTS: On average, cancer patients had survived for 10.1 years with the disease. Using a Cox proportional hazard regression with stepwise variables such as age, diagnosis group, Charlson co-morbidity index, body mass index (BMI)) aR and SR. SR were identified as independent parameters with potential prognostic relevance on survival While aR did not significantly influence survival, SR showed a positive and independent impact on survival (OR = 0.589; 95%-CI: 0.354 - 0.979). This positive effect persisted significantly in the sensitivity analysis of the subgroup of tumour patients and in the subscale 'Achieve satisfaction and well-being' and by tendency in the UICC stages nested for the different diagnoses groups. CONCLUSIONS: Self-regulation might be an independent prognostic factor for the survival of breast and colon carcinoma patients and merits further prospective studies.

Molecular mistletoe therapy: friend or foe in established anti-tumor protocols? A multicenter, controlled, retrospective pharmaco-epidemiological study in pancreas cancer.

Mistletoe is often used as complementary therapy in oncology. The anti-tumor effects of mistletoe (Iscador) are well documented in-vitro in respect to inhibition of cell proliferation, induction of apoptosis, segmental activation of immune competent cells and trapping of chemotherapeutic drugs within cancer cells by modulating the inhibitory potential of P-glycoprotein (P-gp)-mediated transport of cell toxifying substances (cytotoxic drugs). However, the clinical activity of mistletoe treatment remains still controversial. Implementation of mistletoe therapy as supportive care into anti-cancer programs should be based on the best evidence and must continually be evaluated to ensure safety, efficacy, collection of new data, and cost-effectiveness. Useful domains that can be evaluated include symptom control, adherence to conventional treatment protocols, quality of life, individual outcome and potential advantages of a whole-system health approach. Here we report the results of a multicenter, controlled, retrospective and observational pharmaco-epidemiological study in patients suffering from a pancreatic carcinoma. After surgery the patients were treated by adjuvant chemotherapy with gemcitabine supported by Iscador, or with gemcitabine alone, or any other best of care, but not including Iscador. Using a novel methodological pharmaco-epidemiological design and statistical approach it could be shown that Iscador offers benefits--symptom control, overall survival--as supportive care within gemcitabine protocols of patients with surgically resected pancreatic carcinoma.

Validation of a questionnaire measuring the regulation of autonomic function.

BACKGROUND: To broaden the range of outcomes that we can measure for patients undergoing treatment for oncological and other chronic conditions, we aimed to validate a questionnaire measuring self-reported autonomic regulation (aR), i.e. to characterise a subject's autonomic functioning by questions on sleeping and waking, vertigo, morningness-eveningness, thermoregulation, perspiration, bowel movements and digestion. METHODS: We administered the questionnaire to 440 participants (female symbol: N = 316, male symbol: N = 124): 95 patients with breast cancer, 49 with colorectal cancer, 60 with diabetes mellitus, 39 with coronary heart disease, 28 with rheumatological conditions, 32 with Hashimoto's disease, 22 with multiple morbidities and 115 healthy people. We administered the questionnaire a second time to 50.2% of the participants. External convergence criteria included the German version of the Hospital Anxiety and Depression Scale (HADS-D), a short questionnaire on morningness-eveningness, the Herdecke Quality of Life Questionnaire (HLQ) and a short version questionnaire on self-regulation. RESULTS: A principal component analysis yielded a three dimensional 18-item inventory of aR. The subscales orthostatic-circulatory, rest/activity and digestive regulation had internal consistency (Cronbach-alpha: ralpha = 0.65 - 0.75) and test-retest reliability (rrt = 0.70 - 85). AR was negatively associated with anxiety, depression, and dysmenorrhoea but positively correlated to HLQ, self-regulation and in part to morningness (except digestive aR) (0.49 - 0.13, all p < 0.05). CONCLUSION: An internal validation of the long-version scale of aR yielded consistent relationships with health versus illness, quality of life and personality. Further studies are required to clarify the issues of external validity, clinical and physiological relevance.

Impact of complementary mistletoe extract treatment on quality of life in breast, ovarian and non-small cell lung cancer patients. A prospective randomized controlled clinical trial.

Standardized aqueous mistletoe extracts have been applied to cancer patients for several decades as complementary medicine. A multicentric, randomized, open, prospective clinical trial was conducted in three oncological centers in the People's Republic of China in Bejing, Shenyang and Tianjin. Following the guidelines of "Good Clinical Practice" (GCP) this study was performed to get information on efficacy safety and side-effects of the standardized mistletoe extract (sME). Two hundred and thirty-three patients with breast (n=68), ovarian (n=71) and non-small cell lung cancer (NSCLC; n=94) were enrolled into this study. Two hundred and twenty-four patients fulfilled the requirements for final analysis (n=115 treated with sME HELIXOR A; n=109 comprising the control group being treated with the approved immunomodulating phytopharmacon Lentinan). All patients were provided with standard tumor-destructive treatment schedules and complementarily treated with sME or Lentinan during chemotherapy according to treatment protocol. Biometrically, the patients of the control and sME treatment group were comparable regarding distribution, clinical classification (WHO) and treatment protocols. Analysis was performed according to the "Intention to treat principle". Quality of life (QoL) was significantly (p<0.05) improved for patients who were complementarily treated with sME, as determined by the questionnaires FLIC (Functional Living Index-Cancer), TCM (Traditional Chinese Medicine Index) and the KPI (Karnofsky Performance Index) in comparison to the control group. Additionally, the occurrence of adverse events (AEs) was less frequent in the sME than in the control group (total number of AEs 52 versus 90 and number of serious AEs 5 versus 10 in study and control group, most of them due to chemotherapy). Only one serious AE was allocated to complementary treatment in each group (1 angioedema in sME group). All other side-effects of the sME (7 harmless local inflammatory reactions at subcutaneous injection site, 4 cases with fever) were self-limiting and did not demand therapeutic intervention. This study showed that complementary treatment with sME can beneficially reduce the side-effects of chemotherapy in cancer patients and thus improve quality of life.

Orphanin FQ/nociceptin binds to functionally coupled ORL1 receptors on human immune cell lines and alters peripheral blood mononuclear cell proliferation.

Orphanin FQ/nociceptin (OFQ/N) has been shown to modulate nociception, responses to stress and anxiety. We investigated OFQ/N function in human immune cells. We find that monocytic U937, T lymphocytic CEM, and MOLT-4 cell lines express OFQ/N binding sites at levels comparable to that of human SH-SY5Y neuroblastoma cells. We show that OFQ/N receptors are functionally coupled to G proteins in these cells. Finally OFQ/N decreases proliferation of phytohemagglutinin-stimulated peripheral blood mononuclear cells in vitro at doses ranging from 10(-13) to 10(-8) M. Thus, our data suggest that OFQ/N and OFQ/N receptor may act as an immunomodulatory system.

Specific activation of the mu opioid receptor (MOR) by endomorphin 1 and endomorphin 2.

The recently discovered endomorphin 1 (Tyr-Pro-Trp-Phe-NH2) and endomorphin 2 (Tyr-Pro-Phe-Phe-NH2) were investigated with respect to their direct receptor-binding properties, and to their ability to activate G proteins and to inhibit adenylyl cyclase in both cellular and animal models. Both tetrapeptides activated G proteins and inhibited adenylyl cyclase activity in membrane preparations from cells stably expressing the mu opioid receptor, an effect reversed by the mu receptor antagonist CTAP (D-Phe-Cys-Tyr-D-Trp-Arg-Thr-Pen-Thr-NH2), but they had no influence on cells stably expressing the delta opioid receptor. To further establish the selectivity of these peptides for the mu opioid receptor, brain preparations of mice lacking the mu opioid receptor gene were used to study their binding and signalling properties. Endomorphin 2, tritiated by a dehalotritiation method resulting in a specific radioactivity of 1.98 TBq/mmol (53.4 Ci/mmol), labelled the brain membranes of wild-type mice with a Kd value of 1.77 nM and a Bmax of 63.33 fmol/mg protein. In membranes of mice lacking the mu receptor gene, no binding was observed, and both endomorphins failed to stimulate [35S]guanosine-5'-O-(3-thio)triphosphate ([35S]GTPgammaS) binding and to inhibit adenylyl cyclase. These data show that endomorphins are capable of activating G proteins and inhibiting adenylyl cyclase activity, and all these effects are mediated by the mu opioid receptors.

Expression of sulphonylurea receptors in bovine monocytes from animals with a different metabolic rate.

The aim of this study was to investigate the relationship between expression of sulphonylurea receptors (SUR) and metabolic rate (MR). SUR on monocytes and cells from muscle tissue were detected using fluorescent glibenclamide and flow cytometry. Transmembrane potential differences were detected by oxonol dye fluorescence measurements. A bovine model was used to induce differences in the MR by exposure to different ambient temperatures (4 degrees C and 18 degrees C), by different feeding levels (1.0- and 1.6-fold the metabolizable energy requirement for maintenance) and by alpha2-adrenergic stimulation. We found that cells from skeletal muscle (m. semimembranosus), immunochemically identified as smooth muscle cells, skeletal muscle fibres and monocytes, responded in comparable fashions to glibenclamide and ATP, i.e. with a depolarization, and to cromakalim with a polarization, suggesting that monocytes are useful indicators of regulatory events occurring in muscle cells. Glibenclamide fluorescence was assumed to represent SUR associated with KATP channels. Significant differences were detected in the percentage of depolarized monocytes in the different variants of the model. A linear correlation between monocytes that bound fluorescent glibenclamide and the MR was evident (with a coefficient of determination of 0.94) and was reproducible following reduction of the MR, by alpha2-adrenergic stimulation, suggesting that expression is involved in the regulation of whole-body energy expenditure.

Retinoids inhibit adhesion to laminin in human pancreatic carcinoma cells via the alpha 6 beta 1-integrin receptor.

BACKGROUND & AIMS: The initial step in tumor invasion and metastasis is determined by adhesion of tumor cells to basement membranes. To evaluate their potential therapeutic use in controlling local growth and metastasis, the effects of retinoids on the adhesive properties in the human pancreatic carcinoma cell line DAN-G were examined. METHODS: The effects of retinoids on cellular adhesion were assessed by adhesion assays in vitro. The expression of laminin-binding proteins was characterized by Northern blotting, radioimmunoprecipitation, and flow-cytometric analysis. RESULTS: Treatment with retinoids results in a time- and dose-dependent inhibition of DAN-G cell adhesion to fibronection and laminin but not to collagens I, IV, and VI. The adhesion of DAN-G cells to laminin could be blocked completely by anti-alpha 6 and anti-beta 1 antibodies but not by the synthetic peptide YIGSR. Flow-cytometric analysis of DAN-G cells showed no quantitative difference for alpha 6-integrin expression in retinoid-treated and -untreated DAN-G cells. Furthermore, radioimmunoprecipitation showed no difference in the appearance of alpha 6 beta 1-integrin expression after retinoid incubation. CONCLUSIONS: Retinoids decrease pancreatic carcinoma cell adhesion to laminin via an as yet unidentified mechanism involving alteration of the alpha 6 beta 1-integrin receptor function and thereby open interesting perspectives for the modulation of infiltrative growth and metastasis in pancreatic cancer.

The human delta-opioid receptor: genomic organization, cDNA cloning, functional expression, and distribution in human brain.

We have used the mouse delta-opioid receptor (mDOR) cDNA to isolate the mDOR gene and its human homologue. In both species the coding region is interrupted by two introns with conserved exon-intron boundaries located after transmembrane domains 1 and 4. Using the polymerase chain reaction and primers based on the sequence of the cloned human delta-opioid receptor (hDOR) gene, we have obtained a full length cDNA encoding the hDOR from SH-SY5Y neuroblastoma cells. The cDNA sequence is 100% identical to the cloned human genomic sequence and 94% identical to the mouse sequence at the protein level. When expressed in COS cells, hDOR displays nanomolar affinities for delta-selective ligands, whereas the affinities for mu- and kappa-selective ligands are in the micromolar range. The delta agonists [D-Ala2, D-Leu5]enkephalin, cyclic [D-penicillamine2,D-penicillamine5]enkephalin, and BW373U86 efficiently decrease forskolin-induced cAMP levels in hDOR-expressing COS cells, indicating functional coupling of the receptor. The distribution of hDOR mRNA in human brain was investigated using delta-selective reverse transcription-polymerase chain reaction amplification, followed by Southern hybridization with a delta-specific probe. The transcript is found in cortical areas, including olfactory bulb, hippocampus, and amygdala, as well as in basal ganglia and hypothalamus. No expression is detected in internal globus pallidus, thalamus, any investigated brainstem structure, or pituitary gland. Taken together, our results indicate similar structural, pharmacological, functional, and anatomical properties for the hDOR and the mDOR and therefore support the use of rodent models for the study of these receptors in opioid function.

Increased fibronectin-receptor expression in colon carcinoma-derived HT 29 cells decreases tumorigenicity in nude mice.

BACKGROUND/AIMS: Following malignant transformation, epithelial cells of colorectal carcinomas, unlike normal colonic epithelial cells, no longer express the alpha 5 beta 1 fibronectin receptor. We hypothesized that the loss of alpha 5 beta 1 expression might facilitate the tumorigenicity of transformed colonic cells. METHODS: To examine this hypothesis, we established subclones of the human colon adenocarcinoma cell line HT 29, which differ in their fibronectin receptor expression and tested their tumorigenicity in nude mice. RESULTS: Our data indicate that the capacity to form tumors in nude mice after subcutaneous injection was significantly lower for alpha 5-positive than for alpha 5-negative cell clones. In addition, tumors from clones expressing no detectable levels of alpha 5 beta 1 grew rapidly, whereas tumors expressing elevated levels of fibronectin receptor grew slowly. Despite similar rates of adhesion to fibronectin for alpha 5-positive and alpha 5-negative cell clones in vitro, deposition of fibronectin in tumor-surrounding stroma was increased in tumors derived from alpha 5-positive cells. CONCLUSIONS: Our results indicate that an increase of the alpha 5 beta 1-mediated interaction of malignant cells with the extracellular matrix may be responsible for decreased tumorigenicity of malignant transformed cells in colorectal carcinomas.

Application of a hollow fiber membrane cell culture system in medicine.

The Tecnomouse system is useful for cultivating transformed cell lines producing MAbs or recombinant proteins, but human tumor cells can also be propagated for autologous immunization protocols or research properties. Lymphokine-activated killer cell production and stem cell proliferation seem to be possible. Moreover, primary human cells of lymphoid organs can be successfully kept viable over long periods of time in a three-dimensional, tissue-like culture. Therefore, the bioreactor is a tool for the in vitro modulation of a variety of human organs.

[Indications for different collagen metabolism in Crohn disease and ulcerative colitis]. / Hinweise für einen differenten Kollagenmetabolismus bei Morbus Crohn und Colitis ulcerosa.

Very little is currently known regarding the underlying mechanisms involved in the etiology of intestinal strictures in chronic inflammatory bowel disease. The deposition of extracellular matrix components, especially collagens, is thought to play an important role in the etiology of intestinal strictures. The main goal of this study was therefore to investigate the collagen metabolism in patients with inflammatory bowel disease using the in situ hybridization technique. We determined de novo synthesis of the (pro)-collagen mRNA transcripts alpha 1I, alpha 1III, alpha 1IV, alpha 2V as well as the collagen degrading enzyme mRNA transcripts collagenase type I and IV in Crohn's disease and ulcerative colitis and compared the rate of expression semiquantitatively to healthy controls. We found a significant increase of all (pro)-collagen transcripts tested in Crohn's disease and ulcerative colitis as compared to healthy control tissues, indicating an increased de novo synthesis of all collagens in both inflammatory bowel diseases. However, we observed a significant difference in the expression of the collagenase mRNA transcripts between Crohn's disease and ulcerative colitis. Compared to healthy control subjects we were unable to detect a significant difference in the expression of collagenase type I and IV in Crohn's disease; in contrast, we observed a significant increase in the rate of expression for the collagenases in ulcerative colitis as compared to controls or biopsies from patients with Crohn's disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunodetection of multiple species of retinoic acid receptor alpha: evidence for phosphorylation.

Polyclonal and monoclonal antibodies were raised against synthetic peptides (or fusion protein) corresponding to cDNA-deduced amino acid sequences unique to the human and mouse retinoic acid (RA) receptor alpha 1 (hRAR-alpha 1 and mRAR-alpha 1, respectively). Two rabbit polyclonal antibodies directed against either the F region fused to DHFR [RP alpha (F)] or the D2 region [RP alpha (D2)] were selected. Using either immunocytochemistry, Western blotting analysis, or immunoprecipitation, they were found to be specific for human and mouse RAR-alpha 1 proteins produced by COS-1 cells transiently transfected with vectors expressing the RAR-alpha 1 cDNA. Three mouse monoclonal antibodies directed against either the F region [(Ab9 alpha (F) and Ab12 alpha (F)] or the A1 region [Ab10 alpha 1(A1)] recognized transiently expressed human and mouse RAR-alpha 1 proteins, when either immunocytochemistry or immunoprecipitation was used. In addition, Ab9 alpha (F) and Ab12 alpha (F), but not Ab10 alpha 1(A1), revealed the RAR-alpha 1 proteins by Western blotting analysis. Ab9 alpha (F) was also able to "supershift" RAR-alpha 1 protein-RARE oligonucleotide probe complexes in gel retardation assays. All these antibodies recognized also the transiently expressed mRAR-alpha 2 isoform, with the exception of Ab10 alpha 1 (A1), which is specific for the A1 region of RAR-alpha 1. These antibodies have enabled us to detect the presence of mRAR-alpha as multiple species in mouse embryo and adult tissue extracts as well as in embryonal carcinoma (EC) cells. Moreover, we found that one of these species (51 kDa) was phosphorylated in EC cells. This phosphorylation was not affected by RA treatment, but appeared to be dependent on the differentiation state of the EC cells.