Developing with lethal RA levels: genetic ablation of Rarg can restore the viability of mice lacking Cyp26a1

We have previously reported that the retinoic acid (RA) catabolizing enzyme CYP26A1 plays an important role in protecting tail bud tissues from inappropriate exposure to RA generated in the adjacent trunk tissues by RALDH2, and that Cyp26a1-null animals exhibit spina bifida and caudal agenesis. We now show that, in the absence of Cyp26a1, retinoic acid receptor gamma (RARgamma) mediates ectopic RA-signaling in the tail bud. We also show that activated RARgamma results in downregulation of Wnt3a and Fgf8, which integrate highly conserved signaling pathways known for their role in specifying caudal morphogenesis. Ablation of the gene for RARgamma (Rarg) rescues Cyp26a1-null mutant animals from caudal regression and embryonic lethality, thus demonstrating that CYP26A1 suppresses the RA-mediated downregulation of WNT3A and FGF8 signaling pathways by eliminating ectopic RA in gastrulating tail bud mesoderm.     

Infectious nickel tolerance: a reciprocal interplay of tolerogenic APCs and T suppressor cells that is driven by immunization

Previously, we reported that tolerance to nickel, induced by oral administration of Ni(2+) ions, can be adoptively transferred to naive mice with only 10(2) splenic T cells. Here we show that 10(2) T cell-depleted spleen cells (i.e., APCs) from orally tolerized donors can also transfer nickel tolerance. This cannot be explained by simple passive transfer of the tolerogen. The APCs from orally tolerized donors displayed a reduced allostimulatory capacity, a tolerogenic phenotype, and an increased expression of CD38 on B cells. In fact, it was B cells among the APCs that carried the thrust of tolerogenicity. Through serial adoptive transfers with Ly5.1(+) donors and two successive sets of Ly5.2(+) recipients, we demonstrated that nickel tolerance was infectiously spread from donor to host cells. After the transfer of either T cells or APCs from orally tolerized donors, the spread of tolerance to the opposite cell type of the recipients (i.e., APCs and T cells, respectively) required recipient immunization with NiCl(2)/H(2)O(2). For the spread of tolerance from a given donor cell type, T cell or APC, to the homologous host cell type, the respective opposite cell type in the host was required as intermediate. We conclude that T suppressor cells and tolerogenic APCs induced by oral administration of nickel are part of a positive feedback loop that can enhance and maintain tolerance when activated by Ag associated with a danger signal. Under these conditions, APCs and T suppressor effector cells infectiously spread the tolerance to naive T cells and APCs, respectively.     

Immune (y) interferon production by murine T cell lymphomas

Various cloned murine T cell hybridomas and T cell lymphomas were evaluated for their ability to produce interferon (IFN). Two T cell tumor clones, L12-R1 and L12-R4, derived from the spontaneously in vitro transformed cell lines L12 originally established from fetal calf serum-primed C57BL/6 spleen cells were found to produce high IFN amounts upon mitogen stimulation. Phorbol myristate acetate led to maximal IFN production (2187 IU) by L12-R4 cells at concentrations of 2 x 10(-7) M, whereas concanavalin A and phytohemagglutinin induced lower levels of IFN synthesis (160 to 243 IU). None of the cell lines tested produced IFN constitutively or upon lipopolysaccharides stimulation. The IFN was characterized as immune (y) by being labile at pH 2 and neutralized by two rabbit anti-murine IFN-y antisera but not by antiserum to murine leukocyte (alpha) and fibroblast (beta) IFN. Phenotypic characterization of IFN-y-producing cells showed the L12 clones to be Thy-1.2+, Lyt-1+, 23-, and Ig-. The L12-R4 tumor cell therefore provide a unique source of IFN-y for purification, and may represent a useful model for studying the molecular mechanisms involved in T cell differentiation leading to IFN-y production.     

Factors Associated with Slow Disease Progression in Macaques Immunized with an Adenovirus-Simian Immunodeficiency Virus (SIV) Envelope Priming-gp120 Boosting Regimen and Challenged Vaginally with SIVmac251

Rhesus macaques were immunized with a combination vaccine regimen consisting of adenovirus type 5 host range mutant-simian immunodeficiency virus envelope (Ad5hr-SIVenv) recombinant priming and boosting with native SIV gp120. Upon intravaginal challenge with SIVmac251, both persistently and transiently viremic animals were observed (S. L. Buge, E. Richardson, S. Alipanah, P. Markham, S. Cheng, N. Kalyan, C. J. Miller, M. Lubeck, S. Udem, J. Eldridge, and M. Robert-Guroff, J. Virol. 71:8531-8541, 1997). Long-term follow-up of the persistently viremic immunized macaques, which displayed significantly reduced viral burdens during the first 18 weeks postchallenge compared to controls, has now shown that one of four became a slow progressor, clearing virus from plasma and remaining asymptomatic with stable CD4 counts for 134 weeks postchallenge. Reboosting of the transiently viremic macaques did not reactivate latent virus. Rechallenge with two sequential SIVmac251 intravaginal exposures again resulted in partial protection of one of two immunized macaques, manifested by viral clearance and stable CD4 counts. No single immune parameter was associated with partial protection. Development of a strong antibody response capable of neutralizing a primary SIVmac251 isolate together with SIV-specific cytotoxic T lymphocytes were implicated, while CD8(+) T-cell antiviral activity and mucosal immune responses were not associated with delayed disease progression. Our data show that even a third immunization with the same Ad5hr-SIVenv recombinant can elicit significant immune responses to the inserted gene product, suggesting that preexisting Ad antibodies may not preclude effective immunization. Further, the partial protection against a virulent, pathogenic SIV challenge observed in two of six macaques immunized with a vaccine regimen based solely on the viral envelope indicates that this vectored-vaccine approach has promise and that multicomponent vaccines based in the same system merit further investigation.     

Outer membrane permeabilization by the membrane attack complex sensitizes Gram-negative bacteria to antimicrobial proteins in serum and phagocytes

Infections with Gram-negative bacteria form an increasing risk for human health due to antibiotic resistance. Our immune system contains various antimicrobial proteins that can degrade the bacterial cell envelope. However, many of these proteins do not function on Gram-negative bacteria, because the impermeable outer membrane of these bacteria prevents such components from reaching their targets. Here we show that complement-dependent formation of Membrane Attack Complex (MAC) pores permeabilizes this barrier, allowing antimicrobial proteins to cross the outer membrane and exert their antimicrobial function. Specifically, we demonstrate that MAC-dependent outer membrane damage enables human lysozyme to degrade the cell wall of E. coli. Using flow cytometry and confocal microscopy, we show that the combination of MAC pores and lysozyme triggers effective E. coli cell wall degradation in human serum, thereby altering the bacterial cell morphology from rod-shaped to spherical. Completely assembled MAC pores are required to sensitize E. coli to the antimicrobial actions of lysozyme and other immune factors, such as Human Group IIA-secreted Phospholipase A2. Next to these effects in a serum environment, we observed that the MAC also sensitizes E. coli to more efficient degradation and killing inside human neutrophils. Altogether, this study serves as a proof of principle on how different players of the human immune system can work together to degrade the complex cell envelope of Gram-negative bacteria. This knowledge may facilitate the development of new antimicrobials that could stimulate or work synergistically with the immune system.     

Die dauer der phasen im zellzyklus von l-929-zellen

Zusammenfassung Die mittlere Dauer der Phasen des Zellzyklus von L-929-Zellen in Kultur wurde autoradiographisch und impulscytophotometrisch bestimmt. Die Mittelwerte von fünf Untersuchungen wichen biei beden Verfahren nur im Rahmen des statistischen Fehlers voneinander ab. Die Reproduzierbarkeit der ICP-Messungen war besser. Auf Konsequenzen für eine klinische Anwendung wird hingewiesen.

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Duration of the phases of the cell cycle in L-929 cells

Summary The mean duration of the different phases of the mitotic cycle in L-929 cells cultivatedin vitro was determined autoradiographically and also by impulsecytophotometry. The mean values obtained with the two methods each involving 5 experiments were within the frame of statistical error. The reproducibility of the ICP measurements was better. The importance in clinical application is discussed.

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Herrn Prof. Dr. Dr. h. c. mult. B. Rajewsky zum 80. Geburtstag gewidmet.

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Wir danker der Deutschen Forschungsgemeinschaft, Bonn-Bad Godesberg, für die Bereitstellung der Impulscytophotometers.     

Prevalence of Incidental Pancreatic Cysts on 3 Tesla Magnetic Resonance

Objectives

To ascertain the prevalence of pancreatic cysts detected incidentally on 3-Tesla magnetic resonance imaging (MRI) of the abdomen and correlate this prevalence with patient age and gender; assess the number, location, and size of these lesions, as well as features suspicious for malignancy; and determine the prevalence of incidentally detected dilatation of the main pancreatic duct (MPD).

Methods

Retrospective analysis of 2,678 reports of patients who underwent abdominal MRI between January 2012 and June 2013. Patients with a known history of pancreatic conditions or surgery were excluded, and the remaining 2,583 reports were examined for the presence of pancreatic cysts, which was then correlated with patient age and gender. We also assessed whether cysts were solitary or multiple, as well as their location within the pancreatic parenchyma, size, and features suspicious for malignancy. Finally, we calculated the prevalence of incidental MPD dilatation, defined as MPD diameter ≥ 2.5 mm.

Results

Pancreatic cysts were detected incidentally in 9.3% of patients (239/2,583). The prevalence of pancreatic cysts increased significantly with age (p<0.0001). There were no significant differences in prevalence between men and women (p=0.588). Most cysts were multiple (57.3%), distributed diffusely throughout the pancreas (41.8%), and 5 mm or larger (81.6%). In 12.1% of cases, cysts exhibited features suspicious for malignancy. Overall, 2.7% of subjects exhibited incidental MPD dilatation.

Conclusions

In this sample, the prevalence of pancreatic cysts detected incidentally on 3T MRI of the abdomen was 9.3%. Prevalence increased with age and was not associated with gender. The majority of cysts were multiple, diffusely distributed through the pancreatic parenchyma, and ≥ 5 mm in size; 12.1% were suspicious for malignancy. An estimated 2.7% of subjects had a dilated MPD.     

Educational Inequalities in Exit from Paid Employment among Dutch Workers: The Influence of Health,Lifestyle and Work

Background

Individuals with lower socioeconomic status are at increased risk of involuntary exit from paid employment. To give sound advice for primary prevention in the workforce, insight is needed into the role of mediating factors between socioeconomic status and labour force participation. Therefore, it is aimed to investigate the influence of health status, lifestyle-related factors and work characteristics on educational differences in exit from paid employment.

Methods

14,708 Dutch employees participated in a ten-year follow-up study during 1999–2008. At baseline, education, self-perceived health, lifestyle (smoking, alcohol, sports, BMI) and psychosocial (demands, control, rewards) and physical work characteristics were measured by questionnaire. Employment status was ascertained monthly based on tax records. The relation between education, health, lifestyle, work-characteristics and exit from paid employment through disability benefits, unemployment, early retirement and economic inactivity was investigated by competing risks regression analyses. The mediating effects of these factors on educational differences in exit from paid employment were tested using a stepwise approach.

Results

Lower educated workers were more likely to exit paid employment through disability benefits (SHR:1.84), unemployment (SHR:1.74), and economic inactivity (SHR:1.53) but not due to early retirement (SHR:0.92). Poor or moderate health, an unhealthy lifestyle, and unfavourable work characteristics were associated with disability benefits and unemployment, and an unhealthy lifestyle with economic inactivity. Educational differences in disability benefits were explained for 40% by health, 31% by lifestyle, and 12% by work characteristics. For economic inactivity and unemployment, up to 14% and 21% of the educational differences could be explained, particularly by lifestyle-related factors.

Conclusions

There are educational differences in exit from paid employment, which are partly mediated by health, lifestyle and work characteristics, particularly for disability benefits. Health promotion and improving working conditions seem important measures to maintain a productive workforce, particularly among workers with a low education.