Proinflammatory phenotype of iPS cell-derived JAK2 V617F megakaryocytes induces fibrosis in 3D in vitro bone marrow niche

The myeloproliferative disease polycythemia vera (PV) driven by the JAK2 V617F mutation can transform into myelofibrosis (post-PV-MF). It remains an open question how JAK2 V617F in hematopoietic stem cells induces MF. Megakaryocytes are major players in murine PV models but are difficult to study in the human setting. We generated induced pluripotent stem cells (iPSCs) from JAK2 V617F PV patients and differentiated them into megakaryocytes. In differentiation assays, JAK2 V617F iPSCs recapitulated the pathognomonic skewed megakaryocytic and erythroid differentiation. JAK2 V617F iPSCs had a TPO-independent and increased propensity to differentiate into megakaryocytes. RNA sequencing of JAK2 V617F iPSC-derived megakaryocytes reflected a proinflammatory, profibrotic phenotype and decreased ribosome biogenesis. In three-dimensional (3D) coculture, JAK2 V617F megakaryocytes induced a profibrotic phenotype through direct cell contact, which was reversed by the JAK2 inhibitor ruxolitinib. The 3D coculture system opens the perspective for further disease modeling and drug discovery.

Non-canonical Hedgehog signaling mediates profibrotic hematopoiesis-stroma crosstalk in myeloproliferative neoplasms

The role of hematopoietic Hedgehog signaling in myeloproliferative neoplasms (MPNs) remains incompletely understood despite data suggesting that Hedgehog (Hh) pathway inhibitors have therapeutic activity in patients. We aim to systematically interrogate the role of canonical vs. non-canonical Hh signaling in MPNs. We show that Gli1 protein levels in patient peripheral blood mononuclear cells (PBMCs) mark fibrotic progression and that, in murine MPN models, absence of hematopoietic Gli1, but not Gli2 or Smo, significantly reduces MPN phenotype and fibrosis, indicating that GLI1 in the MPN clone can be activated in a non-canonical fashion. Additionally, we establish that hematopoietic Gli1 has a significant effect on stromal cells, mediated through a druggable MIF-CD74 axis. These data highlight the complex interplay between alterations in the MPN clone and activation of stromal cells and indicate that Gli1 represents a promising therapeutic target in MPNs, particularly that Hh signaling is dispensable for normal hematopoiesis.

POS0684 IS UPADACITINIB CAPABLE OF IMPROVING PATIENT-REPORTED OUTCOMES OF RHEUMATOID ARTHRITIS IN A REAL-WORLD SETTING? RESULTS FROM THE POST-MARKETING OBSERVATIONAL UPwArds STUDY

Background

The efficacy of Upadacitinib (UPA), a selective Janus kinase inhibitor, has been evaluated in the SELECT clinical program 1-6. In addition, recent results from the non-interventional UPwArds study further confirmed UPAs clinical effectiveness regarding standard disease activity scores for rheumatoid arthritis (RA) in a real-world setting 7. However, patient-reported outcomes (PROs) as another cornerstone of clinical decision making yet remain to be addressed in the context of a post-marketing setting. This interim analysis, conducted after 250 patients had completed the 6-month follow-up visit, aims to fill this gap.

Objectives

To evaluate the change of selected PROs over 6 months in patients treated with UPA in a real-world data environment.

Methods

UPwArds is a prospective, open-label, multicenter, non-interventional, post-marketing study including adult patients with moderate-to-severe RA (swollen joint count [SJC28] ≥ 3 and inadequate response or intolerance to at least one previous disease-modifying antirheumatic drug). According to the German label, patients were treated with UPA 15 mg once daily, as monotherapy or in combination with methotrexate. For this analysis, the following PROs were included: 0-10 numerical rating scales (NRS) for pain and fatigue, the Health Assessment Questionnaire Disability Index (HAQ-DI), the duration and severity of morning stiffness, the Patient Health Questionnaire 9 (PHQ-9), and the Rheumatoid Arthritis Impact of Disease Questionnaire (RAID). Changes from baseline were evaluated for follow-up periods of 1 month, 3 months, and 6 months. Results are presented for the total sample using descriptive measures reflecting sample size (N), average values (standard deviation) for each assessment and average change scores (standard deviation) for follow-up visits. All data were analyzed as observed, with no imputation of missing data.

Results

483 patients (369 female, 114 male) were included in the study, with available baseline PRO information for 481 patients. 6-months follow-up data were yet available from 279 patients The baseline average age and disease duration were 58.0 (12.3) years and 9.0 (8.0) years, respectively, whereas the mean initial DAS28-CRP was 4.6 (1.0). At baseline, 60.8% of enrolled patients had previously been treated with biologic or targeted synthetic disease-modifying antirheumatic drugs. Overall, PRO scores improved from baseline throughout month 6 with a considerable amelioration at month 3, which was maintained at month 6. Responses were rapid, with improvement already evident at month 1 (Table 1). The NRS pain as a crucial PRO in RA confirmed the previously described pattern of results seen for most of the other PROs (Figure 1).

Table 1.

Baseline scores and average changes from baseline scores

NBaseline scores (SD)NChange from baseline - month 1 (SD)NChange from baseline - month 3 (SD)NChange from baseline - month 6(SD)Pain (NRS)4816.2 (2.2)393-2.2 (2.3)392-2.5 (2.5)258-2.4 (2.4)Fatigue (NRS)4815.5 (2.6)393-1.4 (2.3)393-1.6 (2.4)259-1.5 (2.3)HAQ-DI4711.3 (0.6)380-0.2 (0.3)376-0.2 (0.4)253-0.2 (0.4)Morning stiffness (duration, minutes)43968.9 (63.9)313-25.0 (55.3)296-29.6 (54.9)179-31.6 (51.7)Morning stiffness (severity)4785.2 (2.7)386-1.8 (2.3)393-2.2 (2.6)258-2.2 (2.9)PHQ-94778.7 (5.2)383-1.9 (3.9)381-2.3 (4.0)255-2.2 (3.8)RAID4815.6 (2.0)393-1.7 (1.8)392-2.0 (2.0)258-1.9 (1.9)

Conclusion

This interim analysis confirmed a meaningful improvement regarding included PROs that cover various RA-related symptoms, depressiveness and the impact of symptoms of RA on daily life.

References

[1]Smolen JS, et al. Lancet 2019;393:2303–11

[2]Burmester GR, et al. Lancet 2018;391:2503–12

[3]Genovese MC, et al. Lancet 2018;391:2513–24

[4]van Vollenhoven R, et al. Arthritis Rheumatol 2020;72:1607–20

[5]Fleischmann R, et al. Arthritis Rheumatol 2019;71:1788–800

[6]Rubbert-Roth A, et al. N Engl J Med 2020;383:1511–21

[7]Witte T et al. P0833 at ACR, Nov 5–9, 2021

Acknowledgements

AbbVie funded this study; contributed to its design; participated in data collection, analysis, and interpretation of the data; and in the writing, review, and approval of the abstract. AbbVie and the authors thank all study investigators for their contributions and the patients who participated in this study. No honoraria or payments were made for authorship. The medical writing support was provided by Matthias Englbrecht, Freelance Healthcare Data Scientist (Eckental, Germany) and was funded by AbbVie. Statistical analyses were provided by Dr. Daniela Adolf of StatConsult GmbH (Magdeburg, Germany) which was funded by AbbVie.

Disclosure of Interests

Torsten Witte Grant/research support from: AbbVie, Amgen, Bristol-Myers Squibb, Celgene, Chugai, Gilead, Janssen, Lilly, MSD, Mylan, Novartis, Pfizer, Roche, and UCB, Uta Kiltz Consultant of: AbbVie, Biocad, Eli Lilly and Company, Grünenthal, Hexal, Janssen, MSD, Novartis, Pfizer, Roche, and UCB, Grant/research support from: AbbVie, Amgen, Biogen, Fresenius, GSK, Hexal, Novartis, and Pfizer, Florian Haas Consultant of: AbbVie, Celgene, Novartis, and Pfizer, Grant/research support from: AbbVie, BMS, Celgene, Chugai, MSD, Novartis, Pfizer, Roche, and Sanofi Genzyme, Elke Riechers Consultant of: AbbVie, Chugai, Novartis, and UCB, Grant/research support from: AbbVie, Chugai, Lilly, Janssen, Novartis, Pfizer, Roche, and UCB, Ulrich Prothmann Grant/research support from: AbbVie, Amgen, Bristol-Myers Squibb, Chugai, Glaxo Smith Kline, Novartis, Pfizer, Roche, Sanofi, SOBI, and UCB, Daniela Adolf Shareholder of: Employee of StatConsult and may own stock or options, Employee of: Employee of StatConsult, Carsten Holland Shareholder of: Employee of AbbVie and may own stock or options, Employee of: Employee of AbbVie, Alexander Roessler Shareholder of: Employee of AbbVie and may own stock or options, Employee of: Employee of AbbVie, Kirsten Famulla Shareholder of: Employee of AbbVie and may own stock or options, Employee of: Employee of AbbVie, Konrad Götz Shareholder of: Employee of AbbVie and may own stock or options, Employee of: Employee of AbbVie, Klaus Krueger Grant/research support from: AbbVie, Biogen, BMS, Celltrion, Gilead, Hexal, Janssen, Lilly, Medac, MSD, Novartis, Pfizer, Roche, and UCB

CRISPR/Cas9 editing in conditionally immortalized HoxB8 cells for studying gene regulation in mouse dendritic cells

HoxB8 multipotent progenitors (MPP) are obtained by expression of the estrogen receptor hormone binding domain (ERHBD) HoxB8 fusion gene in mouse BM cells. HoxB8 MPP generate (i) the full complement of DC subsets (cDC1, cDC2, and pDC) in vitro and in vivo and (ii) allow CRISPR/Cas9-mediated gene editing, for example, generating homozygous deletions in cis-acting DNA elements at high precision, and (iii) efficient gene repression by dCas9-KRAB for studying gene regulation in DC differentiation.

Human DC3 Antigen Presenting Dendritic Cells From Induced Pluripotent Stem Cells

Dendritic cells (DC) are professional antigen-presenting cells that develop from hematopoietic stem cells. Different DC subsets exist based on ontogeny, location and function, including the recently identified proinflammatory DC3 subset. DC3 have the prominent activity to polarize CD8⁺ T cells into CD8⁺ CD103⁺ tissue resident T cells. Here we describe human DC3 differentiated from induced pluripotent stem cells (iPS cells). iPS cell-derived DC3 have the gene expression and surface marker make-up of blood DC3 and polarize CD8⁺ T cells into CD8⁺ CD103⁺ tissue-resident memory T cells in vitro. To test the impact of malignant JAK2 V617F mutation on DC3, we differentiated patient-specific iPS cells with JAK2 V617F^het and JAK2 V617F^hom mutations into JAK2 V617F^het and JAK2 V617F^hom DC3. The JAK2 V617F mutation enhanced DC3 production and caused a bias toward erythrocytes and megakaryocytes. The patient-specific iPS cell-derived DC3 are expected to allow studying DC3 in human diseases and developing novel therapeutics.

Agrobacterium tumefaciens Small Lipoprotein Atu8019 Is Involved in Selective Outer Membrane Vesicle (OMV) Docking to Bacterial Cells

Outer membrane vesicles (OMVs), released from Gram-negative bacteria, have been attributed to intra- and interspecies communication and pathogenicity in diverse bacteria. OMVs carry various components including genetic material, toxins, signaling molecules, or proteins. Although the molecular mechanism(s) of cargo delivery is not fully understood, recent studies showed that transfer of the OMV content to surrounding cells is mediated by selective interactions. Here, we show that the phytopathogen Agrobacterium tumefaciens, the causative agent of crown gall disease, releases OMVs, which attach to the cell surface of various Gram-negative bacteria. The OMVs contain the conserved small lipoprotein Atu8019. An atu8019-deletion mutant produced wildtype-like amounts of OMVs with a subtle but reproducible reduction in cell-attachment. Otherwise, loss of atu8019 did not alter growth, susceptibility against cations or antibiotics, attachment to plant cells, virulence, motility, or biofilm formation. In contrast, overproduction of Atu8019 in A. tumefaciens triggered cell aggregation and biofilm formation. Localization studies revealed that Atu8019 is surface exposed in Agrobacterium cells and in OMVs supporting a role in cell adhesion. Purified Atu8019 protein reconstituted into liposomes interacted with model membranes and with the surface of several Gram-negative bacteria. Collectively, our data suggest that the small lipoprotein Atu8019 is involved in OMV docking to specific bacteria.

[What do medical students think of family medicine? Results of an online cross-sectional study in the federal state of Baden-Wuerttemberg]

BACKGROUND

In the context of physician shortages, critical factors influencing career choice need to be better understood. The aim of this study was to explore experiences students have had with family medicine in order to develop additional strategies for recruiting family medicine trainees.

METHODS

Students from the five medical faculties in the federal state of Baden-Wuerttemberg were invited to participate in an online-survey via email. A purpose-built questionnaire was used. In addition to descriptive statistics, analysis included linear partial correlations controlled for age, gender, and semester, which were calculated between the variable "I believe family medicine is an attractive job" and the 31 variables of the survey. Linear regression was used to analyze the influence of experiences with family medicine and statements about family medicine to the perception of family medicine as an attractive specialty.

RESULTS

1299 students participated in the survey. About half of the participants (49.7 %) considered working as a primary care physician to be attractive or partly attractive. 49.6 % of students reported positive experiences with family medicine as a patient and 33.1 % as a family member. 24.3 % reported positive experiences during the compulsory 1-2 weeks general practice internship and 18.1 % during a four weeks elective placement. For 302 participants (23.3 %), family medicine is presented positively in the media. 178 (13.7 %) consider family medicine to have high importance in both undergraduate and postgraduate education. Positive influences on judging attractiveness of family medicine were: own experience with family medicine as a clinical elective (rpart= + 0.450), own experience with family medicine as a patient (rpart= + 0.218), perception that family medicine offers a diversified working day (rpart= + 0.259), and perception that family medicine offers a good salary (rpart= + 0.242).

CONCLUSION

To enable students during undergraduate studies to have practical experience with family medicine seems to be an important influence on judging family medicine attractive.

[Perceptions of the local government about the primary care physicians shortage - a survey among mayors in the Federal State of Baden-Wuerttemberg]

BACKGROUND

Local governments have a crucial role in dealing with the primary care physicians shortage (PS). The aim of this study is to evaluate the perspectives and experiences of the local mayors on this issue.

METHODS

In May 2011, all 1101 mayors in the Federal State of Baden-Wuerttemberg (BW) were invited to participate in the study by filling out a survey developed by the authors. Data were analysed descriptively.

RESULTS

Of the contacted mayors in BW, 63% (n=698) responded. More than 90% of the participants consider it their duty to ensure future primary care. 16% experienced local practice closures due to PS. The infrastructure provided by the communities seems to be at a high level, whereas emergency practices exist in only 15% of the communities at present. Supportive actions to attract new GPs are evaluated as appropriate by almost half of the participants.

CONCLUSIONS

The PS topic is of high relevance for communities in BW. In order to gain future physicians for their region, the majority of the communities are maintaining a high level of infrastructure and are willing to offer more actions. The young generation physicians need to be informed about these existing conditions. Innovative ideas should be implemented in individual communities as pilot projects.

[Development, factor-analytical control and psychometric evaluation of a questionnaire on specialty choices among medical students]

AIM OF THE STUDY

A questionnaire was developed and validated which assesses factors influencing career choices of medical students and their perception of possibilities in general practice.

METHODS

The first questionnaire version, which was developed based on a systematic literature review, was checked for comprehensibility and redundancy using concurrent think aloud. The revised version was filled out by a pilot sample of medical students and the factor structure was assessed using principal component analysis (PCA). The final version was filled out in an online survey by medical students of all 5 Medical Faculties in the federal state of Baden-Wuerttemberg. The factor structure was validated with a confirmatory factor analysis (CFA). Reliability was assessed as internal consistency using Cronbach's α.

RESULTS

The questionnaire comprises 2 parts: ratings of (A) the individual importance and of (B) the possibilities in general practice on 5-point scales. The first version comprising 118 items was shortened to 63 items after conducting interviews using concurrent think aloud. A further 3 items giving no information were removed after piloting the questionnaire on 179 students. The 27 items of part A were structured in 7 factors (PCA): image, personal ambition, patient orientation, work-life balance, future perspectives, job-related ambition, and variety in job. This structure had a critical fit in the CFA applied to the final version filled out by 1 299 students. Internal consistency of the factors was satisfactory to very good (Cronbach's α=0.55-0.81).

CONCLUSION

The questionnaire showed good psychometric properties. Further, not assessed factors influence career choice resulting in unexplained variance in our dataset and the critical fit of the model.

[Aspirations of medical students: "planning for a secure career" - results of an online-survey among students at five medical schools in Germany]

BACKGROUND

In times of shortage of doctors, expectations and interests of the future generation of doctors towards their career aspiration is of major importance. The aim of this study was to analyze expectations of medical students at the five medical schools in the State of Baden-Wuerttemberg (Germany) concerning their career choice and factors influencing it.

METHODS

Between January and February 2010, 1299 medical students (out of 12 062 medical students at the five medical schools) participated in an online-survey. In addition to sociodemographic items, career choice and aspects of planning reliability were raised.

RESULTS

Three quarters of the students assign a medical profession for their future occupation. There is a dominance of internal medicine (n = 152), gynaecology (n = 127), paediatrics (n = 125), surgery (n = 115), anaesthesiology (n = 101), and family medicine (n = 88). The time point of decision varies between the different undergraduate years of medical school and specialty. Students at the beginning of their studies seem to be interested mostly in surgery. During medical school the interests towards internal medicine grows. Regarding planning dependability important aspects for medical students were to work in a job that has a future (61.2 % fully agree), to have a safe job (57.7 %), and to have a safe income (57.1 %). Less important seems to be to have good opportunity to earn money (29.6 %).

CONCLUSIONS

Interest in a certain specialty changes markedly at during medical school. Factors such as economical guarantee, good future prospects and also the studies itself have an essential impact for students on choosing a specific career. Strategies to face physicians' shortage in different specialties need to be close to the needs and expectations of future physicians. This is not only valid for the undergraduate time period but also for the work circumstances of their future.

A SHH-independent regulation of Gli3 is a significant determinant of anteroposterior patterning of the limb bud

The family of GLI proteins (GLI1-3) comprises the intracellular mediators of the hedgehog pathway, which regulates a myriad of developmental processes, one of which is limb development. Whereas GLI1 and GLI2 seem to be dispensable during limb development, GLI3 is especially crucial since all GLI3-associated human congenital diseases comprise limb malformations. Furthermore, Gli3(-/-) mouse embryos exhibit pronounced polydactyly in conjunction with a loss of digit identities. Here we examined how the quantity of GLI3 contributes to its function by using different Gli3 mutants in order to vary overall GLI3 levels. In addition, we made use of the Gli3(Delta699) allele, which encodes a C-terminally truncated version of GLI3, thus mimicking the processed GLI3 isoform (GLI3R). The Gli3(Delta699) mutant made it feasible to analyze isoform-specific contributions of GLI3 within the context of anteroposterior patterning of the limb bud. We revealed a so far unappreciated variation in the quantitative demand for GLI3 within different phases and aspects of distal limb formation. In addition, our analyses provide evidence that unprocessed full-length GLI3 is dispensable for anteroposterior patterning of the limb bud. Instead, digit identities are most likely defined by GLI3 repressor activity alone. Furthermore, we present evidence that the anteroposterior grading of GLI3 activity by the action of SHH is supported by a prototype patterning, which regulates Gli3 independently from SHH.

Radiological findings in individuals at high risk of psychosis

OBJECTIVE

To assess the prevalence of radiological magnetic resonance imaging (MRI) findings in individuals at high risk of schizophrenia.

METHODS

MRI scans from individuals at high risk of schizophrenia (HR; n = 37) were assessed by a radiologist blind to group status and compared with scans from patients with first episode psychosis (FE; n = 30), depressive controls (DC; n = 17), and healthy controls (HC; n = 26).

RESULTS

There was a significantly higher proportion of radiological findings in individuals at high risk of schizophrenia (35%) and patients with first-episode psychosis (40%) than in patients with depression (18%) or healthy controls (12%). These differences were specific to findings regarded as potentially clinically significant as opposed to normal variants; however, there was no indication for medical treatment.

CONCLUSIONS

The results suggest that a large proportion of those at high risk of psychosis have radiological findings on MRI scanning, and that the prevalence of radiological findings in this group is similar to that in patients with first episode psychosis.

HomozygousFt embryos are affected in floor plate maintenance and ventral neural tube patterning

Sonic hedgehog (Shh), produced by the notochord and floor plate cells of the neural tube, plays a critical role in organizing dorsal-ventral patterning in the developing neural tube. We have investigated neural tube development in mouse embryos homozygous for the Fused toes (Ft) mutation, a deletion composed of genes of the Iroquois B (IrxB) cluster and of Fts, Ftm, and Fto. In Ft mutants starting from embryonic day 10.5, the floor plate appeared to degenerate and the notochord failed to undergo ventral displacement from the spinal cord. Consistent with the loss of Shh signalling from the floor plate, V3 neuron generation was reduced in Ft/Ft embryos and the domain of motor neuron generation expanded ventrally at the expense of V2 neurons. These data support the idea that Ft genes play an important role in dorsal-ventral patterning of the neural tube acting to define the extent of motor neuron generation; moreover, the data reveal a previously unanticipated function for Ft genes in the maintenance of the floor plate.

Estimation of x ray overexposure in a childhood leukaemia cluster by means of chromosome aberration analysis

Only multiple X ray diagnostics could be identified as a common risk factor in a leukaemia cluster that appeared between 1985-1989 in the municipality of Sittensen in northern Germany. In order to judge if the effect could be explained by irradiation dose, estimates were done in two of the leukaemia cases and seven former patients of a practice where some of the leukaemia cases had been treated for orthopaedic reasons. The methods used for the reconstruction of doses were physical simulation and biological dosimetry by dicentric chromosomes in peripheral lymphocytes. Compared to the Bremen laboratory control the mean frequency of dicentric chromosomes in the lymphocytes of the seven volunteers was significantly elevated. An overexposure of about 12-fold could be derived compared to state of the art X raying. At least two cases of the leukaemia cluster in Sittensen can therefore be correlated to an overexposure by diagnostic X rays.

Task-specific association of photoreceptor systems and steering parameters in Drosophila

Visual motion processing enables moving fruit flies to stabilize their course and altitude and to approach selected objects. Earlier attempts to identify task-specific pathways between two photoreceptor systems (peripheral retinula cells 1-6, and central retinula cells 7 + 8) and three steering parameters (wingstroke asymmetry, abdomen deflection, hindleg deflection) attributed course control and object fixation to peripheral retinula cells 1-6-mediated simultaneous reactions of these parameters. The present investigation includes first results from fixed flying or freely walking ninaE17 mutants which cannot synthesize the peripheral retinula cells 1-6 photoreceptor-specific opsin. Retention of about 12% of the normal course control and about 58% of the object fixation in these flies suggests partial input sharing for both responses and, possibly, a specialization for large-field (peripheral retinula cells 1-6) and small-field (central retinula cells 7 + 8) motion. Such signals must be combined to perceive relative motion between an object and its background. The combining links found in larger species might explain a previously neglected interdependence of course control and object fixation in Drosophila. -Output decomposition revealed an unexpected orchestration of steering. Wingstroke asymmetry and abdomen deflection do not contribute in fixed proportions to the yaw torque of the flight system. Different steering modes seem to be selected according to their actual efficiency under closed-loop conditions and to the degree of intended turning. An easy experimental access to abdominal steering is introduced.

Role of potassium channels in the control of renin secretion from isolated perfused rat kidneys

This study aimed to assess the relevance of specific potassium channels, such as inwardly or outwardly rectifying and calcium-regulated potassium channels, to the control of renin secretion. For this purpose we examined the effects of the K+ channel blockers 4-aminopyridine (1 mmol/l), barium (100 micromol/l), tetraethylammonium (2 mmol/l) and apamin (200 nmol/l) on basal renin secretion, on renin secretion stimulated by isoproterenol (10 nmol/l) and on the inhibition of renin secretion by angiotensin II (100-300 pmol/l) in the isolated rat kidney perfused at constant pressure. Whilst all four K+ channel blockers increased renal vascular resistance, only 4-aminopyridine and barium attenuated isoproterenol-stimulated renin secretion in an additive fashion and augmented the inhibitory effect of angiotensin II. These effects of K+ channel blockers were not changed by the L-type calcium channel blocker amlodipine (5 pmol/l), indicating that their effects on renin secretion are not due to voltage-operated calcium influx. Our data, moreover, suggest that potassium efflux from renal juxtaglomerular cells is not important for the inhibitory action of angiotensin II on renin secretion. As a consequence it appears that the membrane potential of renal juxtaglomerular cells per se is relevant to renin secretion such that membrane depolarization inhibits the exocytosis of renin whilst hyperpolarization favors renin secretion. By their activity, potassium channels can contribute to membrane hyperpolarization and thus facilitate renin secretion.

Which factor mediates reno-renal control of renin gene expression?

OBJECTIVE

To obtain information about possible pathways mediating the suppression of renin gene expression in the contralateral kidneys of stenosed kidneys.

DESIGN

The effects of unilateral renal denervation and of treatment with an angiotensin II antagonist (losartan) on renal renin gene expression were examined in a two-kidney, one-clip model.

METHODS

Renal renin messenger RNA levels, plasma renin activity, blood pressure and kidney weights were monitored over 10 days in adult male Sprague-Dawley rats with various unilateral reductions of renal blood flow achieved with silver clips of 0.2, 0.3 and 0.4 mm inner diameter.

RESULTS

With all the clip sizes used, renin messenger RNA levels increased transiently in the clipped kidneys, the time course and the magnitude of the increase being dependent on the degree of flow reduction. In the contralateral kidneys clipping caused sustained decreases in renin messenger RNA to levels proportional to the clip size. The suppression of renin gene expression in the contralateral kidneys was not related to compensatory growth of the organs nor to changes in plasma renin activity or arterial pressure. Unilateral denervation of the kidney before clipping had no influence on the characteristic increase and decrease in renin messenger RNA in the stenosed and contralateral kidneys, respectively. Treatment of the rats with losartan led to fourfold increases in renal renin messenger RNA levels and to sixfold increases in plasma renin activity in control rats. A 0.3-mm clip did not further increase renin messenger RNA or plasma renin activity in losartan-treated rats but again led to suppression of renin messenger RNA in the contralateral kidney to 50% of the levels found in the clipped kidneys.

CONCLUSIONS

The results suggest that the suppression of renin gene expression in the contralateral kidneys of stenosed kidneys is not due to compensatory renal growth nor mediated by systemic blood pressure, angiotensin II AT1 receptors or renal nerves. We therefore hypothesize that kidneys with reduced perfusion release a humoral factor that acts as a potent inhibitor of renin gene expression.

Direct correlation of parvalbumin levels with myosin isoforms and succinate dehydrogenase activity on frozen sections of rodent muscle

Parvalbumin (PV) is a soluble Ca++ binding protein which is particularly concentrated in fast muscles of rodents. We have developed a new protocol to fix frozen sections of muscle by formaldehyde vapor, which enabled us to immunochemically stain serial frozen sections for PV. Fiber types were defined on the basis of myosin ATPase stability, and of isomyosins identified by a variety of antibodies because ATPase stability alone yielded ambiguous results in the mouse. Slow Type I fibers in mouse and rat were devoid of PV and had intermediate to high SDH levels. Fast fiber subtypes IIA, IIB, and IIX-like were defined in the mouse on the basis of the similarity of their myosin heavy chain immunoreactivity to these types in the rat. The soleus muscle was usually PV negative, but a small population of strongly PV-positive IIX-like fibers was present in the mouse. In mouse fast muscle, small diameter IIA fibers were PV negative with high SDH activity. In both mouse and rat, PV reactivities of IIB and IIX fibers were higher than those of IIA and I, whereas SDH levels of IIA, IIX, and I fibers were higher than those of IIB. Thus, PV content correlated with the type of myosin ATPase but not with SDH levels. The method described for immunocytochemistry of PV may be applicable to other highly soluble proteins.

Color preferences, extraversion, and neuroticism of art students

Color preferences of 190 art students (Götz & Götz, 1974, 1975) were compared with the corresponding scores on extraversion (E) and neuroticism (N). It was found that the preferences of a group of 27 highly gifted young artists were different from preferences of average and less gifted Ss who had little or no artistic practice. In the latter group extraverts and ambiverts mainly preferred primary and secondary colors (light clear and dark clear tones included), while introverts preferred tertiary colors (earth colors) and achromatics. However, in the group of highly gifted Ss no significant differences between positive and negative rankings in both color categories were found. Neuroticism had no effect on color preferences; this holds for introverts and extraverts and for each single color.

Color preferences of art students: surface colors: II

In a previous study (Götz & Götz, 1974b) the preferences of 14 surface colors were analyzed. While this set contained only one red, one blue, one yellow, etc., the color set of the present investigation was extended, and the preferences of 5 different reds, blues, yellow, etc. were analyzed. Between the five variations of red and yellow, respectively, the greatest affective differences were found, while the opposite was true for the 5 oranges, pinks, and grays. The most preferred colors are 2 reds, 2 blues, and 2 yellows; least preferred are a greenish yellow, a penetrating red-violet, and all 5 pinks. Significant sex differences were found for 8 colors.

Color attitudes of art students and university students. I. Imagined colors

The color attitudes of 182 art students and 156 university students were tested. S's task was first to imagine colors and then to rank them on a seven-point rating scale. The results show that for art students only blue and red are “pleasant,” while gray and pink are “unpleasant” colors. Black and white count as “neutral.” The distributions of all other colors listed by Ss are not statistically different from chance. In comparison, university students show the same preference for blue and red as “pleasant” colors, but they prefer a third color, orange. Not only gray and pink are regarded as “unpleasant,” but also black and violet. White and beige are “neutral” colors. The only sex differences found were for violet in the art students group and for orange in the university students group. The drawbacks of the applied procedure, asking Ss to imagine colors, are discussed.

Introversion-extraversion and neuroticism in gifted and ungifted art students

It is generally assumed that artists are mostly introverted. In order to find out if they are also neurotic 50 gifted and 50 ungifted art students were tested with the Maudsley Personality Inventory. The results showed a clear tendency toward introversion and neuroticism for the gifted group. The mean scores of the ungifted group, on the contrary, were in the vicinity of normality. Next, out of the gifted group 15 highly gifted Ss were selected. Their mean scores on introversion and neuroricism were markedly higher than those of the 35 less gifted Ss.