Abstract OT2-06-01: Highly innovative personalized RNA-immunotherapy for patients with triple negative breast cancer

Background: The treatment of triple negative breast cancer (TNBC) is hampered by the lack of established therapeutic targets such as hormone receptors or HER-2. Chemotherapy and radiotherapy is the standard of care, yet survival rates in TNBC remain poor. Approaches tailored to the patient's individual tumor signature may lead to improved therapeutic outcome. We have set up a clinical workflow covering drug development (from target discovery to manufacturing) and drug release providing a custom-made investigational medicinal product (IMP) for each individual patient.

Trial Design: A phase I/II trial assesses the feasibility, safety and biological efficacy of this personalized immunotherapy in three clinical sites in Germany and Sweden. TNBC patients (pT1cN0M0 – TxNxM0) after completion of initial standard of care therapy will be allocated to one of two study arms. Patients in ARM1 receive 8 vaccination cycles with a personalized combination of shared tumor-associated antigens, selected based on each patient tumor's antigen-expression profile out of a WAREHOUSE of pre-manufactured mRNA vaccine. Patients in ARM2 receive the personalized mRNA WAREHOUSE vaccine followed by 8 vaccination cycles of an on-demand manufactured mRNA MUTANOME vaccine encoding up to twenty unique neo-epitopes of the individual patient identified by next generation sequencing. The mRNAs are administered intravenously as a nanoparticulate lipoplex formulation, which protects RNA from degradation, activates innate immunity, transfects APCs and consequently induces highly potent antigen-specific T-cell responses. The treatment of 12 patients in ARM1 is completed and enrolment of patients for ARM2 has started. Preliminary data show that the RNA-WAREHOUSE approach is feasible and can be applied safely. Biomarker analysis is ongoing. This approach is promising as it addresses the heterogeneity of TNBC.

The TNBC-MERIT trial was initially funded by the EU Commission's FP7 and led by BioNTech AG.

Citation Format: Schmidt M, Bolte S, Frenzel K, Heesen L, Derhovanessian E, Bukur V, Diken M, Gruetzner J, Kreiter S, Klein A, Kuhn A, Langer D, Loewer M, Lindman H, Schneeweiss A, Tuereci O, Sahin U. Highly innovative personalized RNA-immunotherapy for patients with triple negative breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr OT2-06-01.

The multi-target effects of CNI-1493: convergence of anti-amylodogenic and anti-inflammatory properties in animal models of Alzheimer's disease

After several decades of Alzheimer's disease (AD) research and failed clinical trials, one can speculate that targeting a single pathway is not sufficient. However, a cocktail of novel therapeutics will constitute a challenging clinical trial. A more plausible approach will capitalize on a drug that has relevant and synergistic multiple-target effects in AD. We have previously demonstrated the efficacy of CNI-1493 in the CRND8 transgenic AD mouse model. Similar to many anti-inflammatory drugs that were tested in preclinical model of AD, it was speculated that the significant effect of CNI-1493 is due to its established anti-inflammatory properties in rodents and humans. In the present study, we set out to elucidate the protective mechanism of CNI-1493 as a drug simultaneously targeting several aspects of AD pathology. Using C1213, a highly similar analogue of CNI-1493 that lacks anti-inflammatory properties, we show that both compounds directly interact with soluble and insoluble Amyloid β (Aβ) aggregates and attenuate Aβ cytotoxicity in vitro. Additionally, CNI-1493 and C1213 ameliorated Aβ-induced behavioral deficits in nematodes. Finally, C1213 reduced Aβ plaque burden and cognitive deficits in transgenic CRND8 mice to a similar extent as previously shown with CNI-1493. Taken together, our findings suggest anti-amyloidogenic activity as a relevant component for the in-vivo efficacy of CNI-1493 and its analogue C1213. Thus, CNI-1493, a drug with proven safety in humans, is a viable candidate for novel multi-target therapeutic approaches to AD.

Transcriptome-based profiling of yolk sac-derived macrophages reveals a role for Irf8 in macrophage maturation

Recent studies have shown that tissue macrophages (MΦ) arise from embryonic progenitors of the yolk sac (YS) and fetal liver and colonize tissues before birth. Further studies have proposed that developmentally distinct tissue MΦ can be identified based on the differential expression of F4/80 and CD11b, but whether a characteristic transcriptional profile exists is largely unknown. Here, we took advantage of an inducible fate-mapping system that facilitated the identification of CD45(+)c-kit(-)CX3CR1(+)F4/80(+) (A2) progenitors of the YS as the source of F4/80(hi) but not CD11b(hi) MΦ. Large-scale transcriptional profiling of MΦ precursors from the YS stage to adulthood allowed for building computational models for F4/80(hi) tissue macrophages being direct descendants of A2 progenitors. We further identified a distinct molecular signature of F4/80(hi) and CD11b(hi) MΦ and found that Irf8 was vital for MΦ maturation. Our data provide new cellular and molecular insights into the origin and developmental pathways of tissue MΦ.

USP18 lack in microglia causes destructive interferonopathy of the mouse brain

Microglia are tissue macrophages of the central nervous system (CNS) that control tissue homeostasis. Microglia dysregulation is thought to be causal for a group of neuropsychiatric, neurodegenerative and neuroinflammatory diseases, called "microgliopathies". However, how the intracellular stimulation machinery in microglia is controlled is poorly understood. Here, we identified the ubiquitin-specific protease (Usp) 18 in white matter microglia that essentially contributes to microglial quiescence. We further found that microglial Usp18 negatively regulates the activation of Stat1 and concomitant induction of interferon-induced genes, thereby terminating IFN signaling. The Usp18-mediated control was independent from its catalytic activity but instead required the interaction with Ifnar2. Additionally, the absence of Ifnar1 restored microglial activation, indicating a tonic IFN signal which needs to be negatively controlled by Usp18 under non-diseased conditions. These results identify Usp18 as a critical negative regulator of microglia activation and demonstrate a protective role of Usp18 for microglia function by regulating the Ifnar pathway. The findings establish Usp18 as a new molecule preventing destructive microgliopathy.

Progressive replacement of embryo-derived cardiac macrophages with age

Molawi et al. examine the origin and cellular dynamics of macrophages in the heart during postnatal development. Cardiac macrophages derived from CX3CR1⁺ embryonic progenitors persist into adulthood, but the contribution of these cells to resident macrophages declines after birth with diminished self-renewal as the mice age. Over time, the heart is progressively reconstituted with bone marrow–derived macrophages, even in the absence of inflammation.

Cardiac macrophages (cMΦ) are critical for early postnatal heart regeneration and fibrotic repair in the adult heart, but their origins and cellular dynamics during postnatal development have not been well characterized. Tissue macrophages can be derived from embryonic progenitors or from monocytes during inflammation. We report that within the first weeks after birth, the embryo-derived population of resident CX3CR1⁺ cMΦ diversifies into MHCII⁺ and MHCII⁻ cells. Genetic fate mapping demonstrated that cMΦ derived from CX3CR1⁺ embryonic progenitors persisted into adulthood but the initially high contribution to resident cMΦ declined after birth. Consistent with this, the early significant proliferation rate of resident cMΦ decreased with age upon diversification into subpopulations. Bone marrow (BM) reconstitution experiments showed monocyte-dependent quantitative replacement of all cMΦ populations. Furthermore, parabiotic mice and BM chimeras of nonirradiated recipient mice revealed a slow but significant donor contribution to cMΦ. Together, our observations indicate that in the heart, embryo-derived cMΦ show declining self-renewal with age and are progressively substituted by monocyte-derived macrophages, even in the absence of inflammation.

Combination of immunoglobulins and natural killer cells in the context of CMV and EBV infection

Cytomegalovirus (CMV)-specific hyperimmunoglobulin (CMV-HIG) is used to treat and prevent CMV infection in immunocompromised patients, and anti-CD20 monoclonal antibody is successfully used in the treatment for post-transplant lymphoproliferative disease caused by Epstein-Barr virus (EBV). Two immunological approaches have been suggested to further improve the control of viral reproduction in patients with active disease: first, the use of monoclonal antibodies with specificity against viral epitopes and second, coadministration of cells with the capacity to promote antibody-dependent cell-mediated cytotoxicity. Here, we have evaluated the effectiveness of these strategies in vitro (alone and in combination) with neutralization and cytotoxicity assays. Our results indicate that monoclonal antibodies (in particular SM5-1) can be as effective as CMV-HIG in neutralizing-cell-free CMV. Moreover, our data indicate that antibody-mediated elimination (either by moAb or by HIG) of EBV-infected cells can be significantly enhanced by NK cells. Using human NK cells that have been purified, cultured and expanded under GMP conditions, we were able to demonstrate that the combination of NK cells and antibodies could represent a feasible and highly effective clinical approach to achieve control of EBV infections. Especially in leukopenic patients with low numbers of ADCC-promoting cells, the combination of adoptively transferred NK cells and antiviral antibodies offers a promising strategy that should be tested in clinical trials.

Licensing of myeloid cells promotes central nervous system autoimmunity and is controlled by peroxisome proliferator-activated receptor γ

During central nervous system autoimmunity, interactions between infiltrating immune cells and brain-resident cells are critical for disease progression and ultimately organ damage. Here, we demonstrate that local cross-talk between invading autoreactive T cells and auto-antigen-presenting myeloid cells within the central nervous system results in myeloid cell activation, which is crucial for disease progression during experimental autoimmune encephalomyelitis, the animal model of multiple sclerosis. This T cell-mediated licensing of central nervous system myeloid cells triggered astrocytic CCL2-release and promoted recruitment of inflammatory CCR2(+)-monocytes, which are the main effectors of disease progression. By employing a cell-specific knockout model, we identify the nuclear receptor peroxisome proliferator-activated receptor γ (PPARγ) in myeloid cells as key regulator of their disease-determining interactions with autoreactive T cells and brain-resident cells, respectively. LysM-PPARγ(KO) mice exhibited disease exacerbation during the effector phase of experimental autoimmune encephalomyelitis characterized by enhanced activation of central nervous system myeloid cells accompanied by pronounced local CCL2 production and inflammatory monocyte invasion, which finally resulted in increased demyelination and neuronal damage. Pharmacological PPARγ activation decreased antigen-specific T cell-mediated licensing of central nervous system myeloid cells, reduced myeloid cell-mediated neurotoxicity and hence dampened central nervous system autoimmunity. Importantly, human monocytes derived from patients with multiple sclerosis clearly responded to PPARγ-mediated control of proinflammatory activation and production of neurotoxic mediators. Furthermore, PPARγ in human monocytes restricted their capacity to activate human astrocytes leading to dampened astrocytic CCL2 production. Together, interference with the disease-promoting cross-talk between central nervous system myeloid cells, autoreactive T cells and brain-resident cells represents a novel therapeutic approach that limits disease progression and lesion development during ongoing central nervous system autoimmunity.

Intrathecal EBV antibodies are part of the polyspecific immune response in multiple sclerosis

OBJECTIVE

One mechanism underlying the link between multiple sclerosis (MS) and Epstein-Barr virus (EBV) might be a direct CNS infection. Viral CNS infections cause elevated antibody indices (AIs). Elevated EBV AIs were found in MS; however, patients with MS frequently show a polyspecific intrathecal immune response with elevated antiviral AIs. To discriminate whether elevated EBV AIs indicate a virus-driven or a polyspecific intrathecal immune response, we determined the intrathecal fraction of anti-EBV antibodies.

METHODS

The fraction of intrathecally synthesized EBV-specific immunoglobulin G (IgG) of the total intrathecally synthesized IgG (F(S) anti-EBV) was determined in 24 patients with a clinically isolated syndrome (CIS) or MS and 3 patients with cerebral posttransplantation lymphoproliferative disorder (PTLD), all of whom had elevated EBV AIs. F(S) anti-measles and AIs for measles, rubella, varicella zoster, and herpes simplex virus were measured as well. The prevalence of an elevated EBV AI was analyzed in another 36 patients with CIS.

RESULTS

Median F(S) anti-EBV in patients with CIS/MS was low (0.65%) and did not differ from F(S) anti-measles (0.9%). Median F(S) anti-EBV was about 40-fold higher in patients with cerebral PTLD than in patients with CIS/MS. All 24 patients with CIS/MS with an elevated EBV AI had at least one further elevated antiviral AI. Only 2 of 36 (5.6%) patients with CIS showed an intrathecal synthesis of anti-EBV antibodies.

CONCLUSIONS

Intrathecally produced anti-EBV antibodies are part of the polyspecific intrathecal immune response in CIS/MS and only rarely detectable in patients with CIS, both arguing against a direct CNS infection with EBV in patients with CIS/MS.

Oesophagostomum bifurcum-induced nodular pathology in a highly endemic area of Northern Ghana

Human infection with Oesophagostomum bifurcum is rare globally, but focally endemic and common in Ghana and Togo. Two clinical presentations are identified: uni-nodular disease, which may be recognized as a 'Dapaong Tumour', and multi-nodular disease. Here, we describe the prevalence of O. bifurcum infection and the association with nodular pathology in northern Ghana. The study was performed in October 2002. Out of a well-defined population of approximately 18000, 928 subjects of all ages were randomly selected for parasitological and ultrasound examination. In stool cultures, 44% had detectable third-stage O. bifurcum larvae present. Females were more often infected than males (P<0.05). In 34% of the samples, nodules were detected along the colon wall, with the ascending and the transverse colon being the most affected regions. Significant correlations existed between the intensity of infection and the presence of nodules, both at the village and the individual level (P<0.001 for both). Patients with multi-nodular pathology had significantly higher larval counts than patients with uni-nodular pathology. The present data suggest that nodular pathology, and probably the severity of the disease, are directly related to intensity of the infection.

Evidence for a long-term effect of a single dose of praziquantel on Schistosoma mansoni-induced hepatosplenic lesions in northern Uganda

Treatment with praziquantel reduces the prevalence and intensity of Schistosoma mansoni infection. However, reversibility of periportal fibrosis of the liver, which potentially leads to fatal complications, is not unequivocally substantiated. In the Nile District of Uganda, 460 patients were parasitologically (Kato-Katz method) and ultrasonographically examined during October 1991, October 1992, and May 1994. Treatment with praziquantel at a dosage of 40 mg per kilogram of body weight was given in October 1991 and October 1992 to 460 individuals (group A). Another 192 patients were seen during the baseline study in October 1991 and missed the follow-up in October 1992 but took part in the second follow-up in May 1994. Thus, they received praziquantel only once in October 1991 (group B) and had an interval of 2.7 years until the next investigation in May 1994. Periportal thickening (PT) of the liver was assessed by ultrasound at each time point. Praziquantel therapy reduced the prevalence of S. mansoni in group A from 84% in 1991 to 31% in 1992 and 30% in 1994. The respective intensities of infection (geometric means of egg output) were 81 eggs per gram (epg) of stool in 1991, 31 epg in 1992, and 30 epg in 1994. Periportal thickening was found in 46% of patients in 1991, 32% of patients in 1992, and 35% of patients in 1994. Reversibility of PT was influenced by age (markedly lower reversibility in individuals older than 30 years) and sex (women and girls responded less favorably than did men and boys). Surprisingly, no significant difference was detected between group A and group B with respect to reversibility of PT The outcome between the 2 groups did not differ significantly. This may indicate that a single dose of praziquantel (as given to group B) may have a longer lasting effect than previously thought, that is, more than 2.5 years.

Deficiency of laryngeal collagen type II in an infant with respiratory problems

A dysmorphic infant is described who presented with laryngeal collapse leading to intubation and respiratory problems that were assigned clinically to the Sussman syndrome. The baby had repeated episodes of respiratory distress necessitating assisted ventilation. At 6 months old, uvulopharyngopalatotomy was done to enlarge the supraglottic airway without any benefit. Surgical reduction of the tongue and cricoid splitting did not ameliorate the respiratory distress; repeated extubation attempts failed with the baby developing stridor, respiratory distress, and episodes of cardiac arrest. At 10 months old he developed seizures and computed tomography showed diffuse cerebral atrophy consisted with hypoxic-ischaemic damage. He died at 17 months old. Western blots using antibodies against collagen alpha 1 (II) showed an absence of collagen type II in laryngeal tissue, which may explain the laryngeal collapse and impaired respiratory functions.

Intratracheal furosemide in infants after cardiac surgery: its effects on lung mechanics and urinary output, and its levels in plasma and tracheal aspirate

OBJECTIVE

Recent studies have suggested direct pulmonary effects of furosemide in asthmatics and infants with bronchopulmonary dysplasia. We tested the hypothesis that intratracheally administered furosemide also increases respiratory compliance in children after cardiac surgery, and investigated whether furosemide has a topical and/or systemic action.

STUDY DESIGN

Prospective study with intra-individual control. In twelve infants and toddlers (age: 10 +/- 8 months, weight: 6.9 +/- 3 kg) mechanically ventilated for compromised lung mechanics after cardiac surgery, 0.5 mg/kg furosemide was intratracheally administered to the lungs. Lung mechanics were serially assessed using a computerised system (Sensormedics 2600) during a 2 h control and 2 h intervention period. Urine output was measured by an indwelling bladder catheter and levels of furosemide were determined in blood and tracheal aspirates.

RESULTS

Static compliance improved within 30 min in all patients, reached a maximum of 44 (20-85)% above baseline and remained improved throughout the study (p < 0.05). An immediate, short and significant diuretic effect of intratracheally applied furosemide was observed. Furosemide levels 1 h after intervention were 795 ng/ml in the blood and 431 micrograms/ml (i.e. 1000-fold higher) in the tracheal aspirate. Changes in compliance were correlated only to urine output values over the 2 h (r = 0.82, p = 0.044, n = 9) after furosemide administration.

CONCLUSION

We conclude that intratracheally applied furosemide improves static compliance in infants and toddlers with compromised lung mechanics after cardiac surgery. We demonstrated that furosemide is absorbed from the lung and has a systemic effect within 15 min after its intratracheal instillation.

Preoperative ECMO in congenital cyanotic heart disease using the AREC system

BACKGROUND

In cyanotic congenital heart disease, oxygen delivery is impaired either by reduced pulmonary perfusion or by limited entry of oxygenated blood into the systemic circulation. Additional impairment of oxygen delivery (eg, in pulmonary hypertension) leads to hypoxic cerebral damage. Preoperative extracorporeal membrane oxygenation enables oxygenation in otherwise untreatable cases.

METHODS

In 3 neonates suffering from cyanotic congenital heart disease (1 with tricuspid atresia and 2 with transposition of the great arteries) with arterial desaturation despite application of prostaglandins, balloon atrioseptostomy, and eventually inhaled nitric oxide during intermittent positive-pressure ventilation with an inspired oxygen fraction of 1, oxygenation could only be established by means of preoperative extracorporeal membrane oxygenation. We used a venovenous single-lumen cannula tidal-flow extracorporeal membrane oxygenation system described by Chevalier and associates that has previously been used for extracorporeal lung support. In this system, called AREC (assistence respiratoire extra-corporelle), alternating clamps and a nonocclusive roller pump were used.

RESULTS

All 3 survived.

CONCLUSIONS

We conclude that the AREC system enables sufficient preoperative oxygenation in patients with cyanotic congenital heart disease and hypoxia in spite of all conventional therapeutic means. This provides a stable preoperative condition for elective palliation or correction.

[Therapy refractory arterial hypotension after heart operation]

Adrenalin insufficiency associated with adrenal hemorrhage, is a rare complication after cardiac surgery in neonates. A boy suffering from transposition of the great arteries, who had an arterial switch-operation on day three of his life, acquired a bilateral adrenal hemorrhage. Clinically the situation resembled a septic shock. Despite large doses of catecholamines, he continued to have severe arterial hypotension, anuria, and kyperkalemia. The clinical condition did not change, although sepsis specific therapy was initiated. Consequently adrenal insufficiency, as a possible postoperative complication, was considered and prednisolon, initially in a dose of 15 mg/kg/d, was administered. The clinical condition improved dramatically. The diagnosis could be confirmed by ultrasound examination and determination of cortisol and ACTH plasma levels. Adrenal insufficiency was only transitory, adrenal sonography on day 135 returned to normal. The surgical procedure on heart-lung bypass, the obligatory anticoagulation and the perioperative stress have to be considered as pathogenetic factors.

Therapeutic strategy in a 9-month-old child with pulmonary sling: need for bronchoscopic evaluation

A 9-month-old child presented suffering from repeated severe infections of the lower respiratory tract. Bronchoscopy revealed a tracheal stenosis, suggestive of a vascular anomaly of the great arteries. A second significant stenosis of the left main stem bronchus was observed that was suspected to be due to a ligamentum arteriosum. Heart catheterization confirmed the diagnosis of an abnormal origin of the left pulmonary artery (pulmonary sling). Based on the bronchoscopic and angiographic findings a pulmonary ring was suspected. A dissection of the ligamentum arteriosum was performed. At readmission 4 weeks postoperatively the child was asymptomatic and the left main bronchus was patent.

Quasistatic volume-pressure curve to predict the effects of positive end-expiratory pressure on lung mechanics and gas exchange in neonates ventilated for respiratory distress syndrome

The shape of the volume-pressure (V/P) curve indicates alveolar collapse if it is convex to the pressure axis and indicates overdistension if it is concave. Positive end-expiratory pressure (PEEP) should either improve or decrease compliance and oxygenation in neonates ventilated for respiratory distress syndrome (RDS), depending on predominance of either alveolar collapse or overdistension. To test this hypothesis, we determined quasistatic V/P curves in 13 preterm neonates and characterized their shape by an alveolar distension index (ADI) at PEEP levels of 2, 4, and 6 cm H2O. We calculated the ADI dividing the V/P ratio at a low tidal volume by the V/P ratio at a high tidal volume. This ADI was then related to the effect of PEEP changes on respiratory compliance and alveolar to arterial oxygen tension difference (AaDO2). ADI was assumed to indicate alveolar collapse if less than 1 and overdistension if more than 1. An increased PEEP in neonates with alveolar collapse (ADI less than 1) decreased AaDO2 more (12 vs 10 mm Hg/cm PEEP, not significant) and decreased compliance less (3 vs 17%/cm PEEP; P < 0.05) than in those neonates with alveolar overdistension (ADI more than 1). Conversely, a decreased PEEP in neonates with alveolar overdistension increased compliance more (19 vs 5%; not significant) and increased AaDO2 less (7 vs 26 mm Hg; P < .01) than in those with alveolar collapse. AaDO2 and compliance changes after PEEP alterations were significantly correlated to the ADI before PEEP alterations (P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Subcutaneous recombinant human erythropoietin in children with renal anemia on continuous ambulatory peritoneal dialysis

Subcutaneous recombinant human erythropoietin (rHuEpo) treatment of renal anemia was performed in four boys and eight girls on CAPD, aged 0.8-12.5 (mean 7.4) years. In contrast to previous studies, our therapeutic goal was not set with a hematocrit of 30% but with full correction of anemia. Following a maximum weekly rHuEpo dosage of median 120 (range 100-240) IU/kg body weight, hematocrit increased in 10 children from 24 (14-29)% within 12 (4-17) weeks to 40.1 (33.5-48.4)%. The weekly increase in hematocrit was 1.27 (0.5-3.1)%. The corrected reticulocyte count increased from 1.3 (0.7-1.8)% to 2.3 (1.4-3.9)% within 4 (2-6) weeks. Eight children fulfilled the protocol; six with an uncomplicated course were able to maintain a hematocrit of 37.1 (35.1-42.7)% with only one sc medication per week of approximately two-thirds of their highest weekly rHuEpo dosage. No serious adverse effect of rHuEpo therapy was observed.

Structure and regulated expression of angiotensin-converting enzyme and the receptor for angiotensin II

The renin-angiotensin system maintains a homeostasis of blood pressure and blood volume. One component of this system is angiotensin-converting enzyme (ACE). There are two isozymes of ACE. The protein produced by vascular endothelium is termed "somatic ACE" and is regulated as a function of the growth state of these cells in vitro. The second isozyme, "testis ACE," is only produced by developing spermatozoa. The two ACE isozymes are the result of two distinct promoter regions within the ACE gene. Angiotensin II binds to specific receptors on the surface of cells. We have isolated cDNA encoding the AT1 subtype of receptor. This subtype is responsible for the hemodynamic consequences of angiotensin.

[Acute renal vein thrombosis in children. Early detection with duplex and color-coded Doppler ultrasound]

Two children with clinically suspected renal vein thrombosis were evaluated by duplex Doppler sonography and colour flow imaging. Both cases presented unspecific findings with an enlarged kidney and loss of cortico-medullary delineation on gray-scale ultrasound, but an unusual flow pattern with retrograde plateau-like frequency shifts during diastole. No venous signal could be obtained. By colour flow imaging only the main renal artery and its proximal branches could be visualised with a reverberating oscillation of blood flow. In addition, partial thrombosis of inferior vena cava in one patient and iliac vein thrombosis in the other could be demonstrated. Clinical improvement during fibrinolytic therapy in one case and nephrectomy in the other case confirmed the diagnosis.

The genomic organization of the rat AT1 angiotensin receptor

The AT1 receptor subtype modulates all of the hemodynamic effects of the vasoactive peptide, angiotensin II. In this report, we investigate the genomic organization of this important receptor. A rat genomic library was screened with fragments from the 5' region of a previously cloned cDNA, pCa18b, encoding the rat AT1 receptor. Two lambda clones were isolated and the hybridizing restriction fragments were sequenced. Comparison of the genomic and cDNA sequences reveals that the rat AT1 receptor has three exons. Two of the exons encode 5' untranslated sequence while the third exon encompasses the entire coding region, a small portion of the 5' untranslated region and the entire 3' untranslated sequence. Further analysis of the genomic sequence 5' to the start site of pCa18b demonstrates typical sequence motifs found in many eukaryotic promoters including a TATA box, a cap site and a potential Sp1 binding site. Southern analysis of genomic DNA indicates that the AT1 receptor subtype represented by pCa18b is encoded by one gene within the rat genome.