Human peripheral blood monocytes release a 30,000 dalton factor (30 KD MF) that stimulates immunoglobulin production by activated B cells

Supernatants (SN) of well-washed adherent human monocytes, obtained from T cell-depleted peripheral blood mononuclear cells, contain a 30,000 dalton protein (30 KD MF) that increases immunoglobulin (Ig) synthesis by EBV-activated B cells two- to fourfold. This factor is released spontaneously during the first 20 hr after monocytes are placed in culture. SN containing 30 KD MF are inactive in the thymocyte co-stimulator assay, under conditions that will detect as little as 0.5 U of purified IL 1. The addition of autologous T cells to isolated adherent monocytes, previously depleted of T cells, suppresses the release or activity of this B cell stimulator in a dose-dependent manner. In addition, 30 KD MF stimulates a two- to fourfold increase in IgA production by cells of an EBV-transformed B cell line (JB/FF line) without increasing incorporation of [3H]thymidine. In contrast, stimulation of this B cell line with up to 10 U of purified IL 1 increases IgA synthesis by less than 50%, and addition of up to 100 U of recombinant IL 2 causes no change whatsoever in IgA production. However, co-stimulation with 30 KD MF and recombinant IL 2 or recombinant gamma-interferon induces more Ig production than is caused by the monocyte factor alone. These observations suggest that the monocyte, in addition to acting as an antigen-presenting cell and source of IL 1, facilitates B cell differentiation by producing a factor which acts both independently and in synergy with cytokines produced by T cells to stimulate Ig production by B lymphocytes.     

Effects of gamma-irradiation on chromosomes of cultured lymphocytes from rheumatoid arthritis patients and their family members

Increased rates of spontaneous or induced chromosome breakage are seen in many types of diseases, including the 'collagen-type' autoimmune diseases. Using a 60Co gamma cell, we irradiated lymphocyte cultures from three related rheumatoid arthritis patients, their immediate family members, and two unrelated rheumatoid arthritis patients. Although these individuals had not shown abnormally high levels of spontaneous chromosome breakage, they did show an abnormal sensitivity to irradiation, which was manifested in several ways. Two of the probands showed induced breakage rates that were twice as high as those seen in controls. In addition, the reduction of mitotic index, due either to increased cell death or to induction of a G2 lag period, was higher in the arthritis group (including non-symptomatic family members) than in the control group. Finally, we observed a high frequency of an unusual type of cell in the arthritis group. These unusual cells resembled c-anaphases seen with extended colcemid treatment, and may indicate that the mitotic apparatus in cells from this group is particularly sensitive to ionizing radiation.     

Identification and DNA sequence of fixZ, a nifB-like gene from Rhizobium leguminosarum.

Previously, several mutants which nodulated peas but which failed to fix nitrogen were isolated following Tn5 mutagenesis of pRL 1JI, a symbiotic plasmid of Rhizobium leguminosarum. Two of these alleles, fix52::Tn5 and fix137::Tn5 were in a region of pRL 1JI which hybridized to a probe that contained the nifA gene and the amino-terminal region of the nifB gene of Klebsiella pneumoniae. The nitrogen fixation defect of the fix52::Tn5 mutant strain was corrected by a 2.0kb fragment of the corresponding wild-type DNA cloned in a wide host-range plasmid. The DNA sequence of this region revealed an open reading frame corresponding to the gene within which the fix52::Tn5 allele was located. The polypeptide corresponding to this open reading frame had a deduced molecular weight of 39,936 and the gene was termed fixZ. The deduced amino acid sequence of the fixZ gene product contained two clusters of cysteine residues, suggesting that the protein may contain an iron-sulphur cluster. The sequence of the fixZ polypeptide was very similar to the sequence of the K. pneumoniae nifB gene (provided by W. Arnold and A. Pühler) which is required for the synthesis of the FeMo-cofactor of nitrogenase. It was shown that the previously observed hybridization was due to homology between the amino terminal regions of fixZ and nifB. Upstream from fixZ was found another open reading frame whose 5' terminus was not established, but within which was located the fix137::Tn5 allele. This gene was termed fixY. The deduced amino acid sequence of the sequenced part of fixY showed similarity to that of the regulatory nifA gene of K. pneumoniae (provided by W. J. Buikema and F. M. Ausubel). Thus in R. leguminoarum the fix genes that correspond to the nifA and nifB genes are in the same relative orientation as in K. pneumoniae.     

Development of cell surface saccharides on embryonic pancreatic cells

Using a battery of seven lectin-ferritin conjugates as probes for cell surface glycoconjugates, we have studied the pattern of plasmalemmal differentiation of cells in the embryonic rat pancreas from day 15 in utero to the early postpartum stage. Our results indicate that differentiation of plasmalemmal glycoconjugates on acinar, endocrine, and centroacinar cells is temporally correlated with development and is unique for each cell type, as indicated by lectin-ferritin binding. Specifically, (a) expression of adult cell surface saccharide phenotype can be detected on presumptive acinar cells as early as 15 d in utero, as indicated by soybean agglutinin binding, and precedes development of intracellular organelles characteristic of mature acinar cells; (b) maturation of the plasmalemma of acinar cells is reached after intracellular cytodifferentiation is completed, as indicated by appearance of Con A and fucoselectin binding sites only at day 19 of development; conversely, maturation of the endocrine cell plasmalemma is accompanied by "loss" (masking) of ricinus communis II agglutinin receptors; and (c) binding sites for fucose lectins and for soybean agglutinin are absent on endocrine and centroacinar cells at all stages examined. We conclude that acinar, centroacinar, and endocrine cells develop from a common progenitor cell(s) whose plasmalemmal carbohydrate composition resembles most closely that of the adult centroacinar cell. Finally, appearance of acinar lumina beginning at approximately 17 d in utero is accompanied by differenetiation of apical and basolateral plasmalemmal domains of epithelial cells, as indicated by enhanced binding of several lectin-ferritin conjugates to the apical plasmalemmal, a pattern that persists from this stage through adult life.     

Contribution to the knowledge of Bulgarian serpentine grasslands and their relationships with Balkan serpentine syntaxa

Serpentine areas, including those in Bulgaria, are rich in endemic taxa, and still remain to be investigated phytocoenologically. We analyse the vegetation types in various sites and compare them with those in other Balkan countries. The main objectives were (1) to explore and describe the relationships between the vegetation in the serpentine areas investigated in Bulgaria with those in the Balkan Peninsula and (2) to explore and classify the diversity of vegetation in grasslands on serpentine rocks in eastern Rhodope, Bulgaria. The classic methodology of the Braun-Blanquet school was applied to the exploration of the vegetation. Average linkage method (unweighted pair group method with arithmetic mean) and principal coordinate analysis were used to evaluate floristic and synoptic similarities. As a result, the new endemic association Onosmo pavlovae-Festucetum dalmaticae was proposed. This association can be included in the alliance Alyssion heldreichii Bergmeier et al. 2009, newly described on serpentine rocks in northern Greece. Our data confirmed the existence of similar or vicariant endemic syntaxa (associations) on isolated serpentine terrains in northern Greece and south-eastern Bulgaria.     

Age-Specific Mortality During the 1918 Influenza Pandemic: Unravelling the Mystery of High Young Adult Mortality

The worldwide spread of a novel influenza A (H1N1) virus in 2009 showed that influenza remains a significant health threat, even for individuals in the prime of life. This paper focuses on the unusually high young adult mortality observed during the Spanish flu pandemic of 1918. Using historical records from Canada and the U.S., we report a peak of mortality at the exact age of 28 during the pandemic and argue that this increased mortality resulted from an early life exposure to influenza during the previous Russian flu pandemic of 1889–90. We posit that in specific instances, development of immunological memory to an influenza virus strain in early life may lead to a dysregulated immune response to antigenically novel strains encountered in later life, thereby increasing the risk of death. Exposure during critical periods of development could also create holes in the T cell repertoire and impair fetal maturation in general, thereby increasing mortality from infectious diseases later in life. Knowledge of the age-pattern of susceptibility to mortality from influenza could improve crisis management during future influenza pandemics.

“The war is over – and I must go” Egon Schiele, 1890–1918.

     

Dysbiosis of upper respiratory tract microbiota in elderly pneumonia patients

Bacterial pneumonia is a major cause of morbidity and mortality in elderly. We hypothesize that dysbiosis between regular residents of the upper respiratory tract (URT) microbiome, that is balance between commensals and potential pathogens, is involved in pathogen overgrowth and consequently disease. We compared oropharyngeal microbiota of elderly pneumonia patients (n=100) with healthy elderly (n=91) by 16S-rRNA-based sequencing and verified our findings in young adult pneumonia patients (n=27) and young healthy adults (n=187). Microbiota profiles differed significantly between elderly pneumonia patients and healthy elderly (PERMANOVA, P<0.0005). Highly similar differences were observed between microbiota profiles of young adult pneumonia patients and their healthy controls. Clustering resulted in 11 (sub)clusters including 95% (386/405) of samples. We observed three microbiota profiles strongly associated with pneumonia (P<0.05) and either dominated by lactobacilli (n=11), Rothia (n=51) or Streptococcus (pseudo)pneumoniae (n=42). In contrast, three other microbiota clusters (in total n=183) were correlated with health (P<0.05) and were all characterized by more diverse profiles containing higher abundances of especially Prevotella melaninogenica, Veillonella and Leptotrichia. For the remaining clusters (n=99), the association with health or disease was less clear. A decision tree model based on the relative abundance of five bacterial community members in URT microbiota showed high specificity of 95% and sensitivity of 84% (89% and 73%, respectively, after cross-validation) for differentiating pneumonia patients from healthy individuals. These results suggest that pneumonia in elderly and young adults is associated with dysbiosis of the URT microbiome with bacterial overgrowth of single species and absence of distinct anaerobic bacteria. Whether the observed microbiome changes are a cause or a consequence of the development of pneumonia or merely coincide with disease status remains a question for future research.