Cardiac hypertrophy in rats after supravalvular aortic constriction. I. Size and number of cardiomyocytes, endothelial and interstitial cells

The ascending aorta of 22 adult male Sprague-Dawley rats was constricted with a silver ring, and 25 animals were subjected to a sham-operation. The hearts, including the main arteries, were fixed by retrograde perfusion 3, 7, 14, 21 and 35 days after the operation. The cross-sectional area of the aorta was reduced by the constriction to an average of 20% of the values found after sham-operation. Twenty-one days after the constriction the weight of the left ventricular myocardium including the septum was increased 1.7-fold compared with controls. No further increase in weight was observed 35 days after the operation. The relative volumes of the tissue components remained largely constant in the subepicardial myocardium. In the subendocardial myocardium, however, the volume fraction of interstitial and, to a lesser extent, of endothelial tissue was significantly increased. Twenty-one days after constriction the estimated total volumes of the different myocardial components per left ventricle were increased 1.7-fold for heart muscle parenchyma, 1.8-fold for endothelial tissue, 2.9-fold for interstitial tissue, and 1.3-fold for capillary lumina compared with controls. At 35 days, only the interstitial tissue showed a further increase to 4.8-fold of control values. The mean cardiomyocyte volume was increased after aortic constriction in proportion to the increase in left ventricular weight, i.e. 1.7-fold over controls at 21 days. After 35 days its value was 29,500 +/- 790 micron 3 in rats subjected to aortic constriction compared with 16,800 +/- 640 micron 3 in controls. At this time the estimated number of cardiomyocytes per left ventricle showed no significant differences between experimental animals (2.9 X 10(7)) and controls (3.1 X 10(7)). Endothelial and interstitial cells were not only increased in average single cell volume (1.3-fold and 2.0-fold, respectively), but also in number per left ventricle (1.4-fold and 2.7-fold, respectively). Two-dimensional parameters indicated that during hypertrophy the capillary supply lagged behind the overall mass increase but achieved control levels on termination of hypertrophic growth at 35 days. These results show that even in pronounced hypertrophy the increase in mass of the myocardial parenchyma in the rat is due exclusively to an enlargement of cardiomyocytes (hypertrophy), whereas in endothelial and interstitial tissues enlargement of cells as well as increase in cell number (hyperplasia) also plays a role.     

SV40 T antigen and telomerase are required to obtain immortalized human adult bone cells without loss of the differentiated phenotype.

In most human primary bone cells, SV40 T-antigen expression was able to expand life span for a few passages before cells undergo growth arrest, described as crisis. In this study, telomerase activity was reconstituted in human osteoblast precursors (hPOB cells) and marrow stromal cells (Saka cells) transformed with the SV40 T antigen. Bone cells with telomerase activity were able to bypass crisis and show unlimited life span. Despite chromosomal aberrations observed in hPOB-tert cells, these immortalized precursors were able to differentiate into osteoblasts like precrisis hPOB cells. Saka-tert cells enhanced the formation of human osteoclast-like cells in a similar manner as Saka cells. These results demonstrate that reconstitution of telomerase activity in transformed SV40 T-antigen human osteoblast precursors or marrow stromal cells leads to the generation of immortalized cells with a preserved phenotype.     

Developmental morphology of Ledermanniella bowlingii (Podostemaceae) from Ghana

 Ledermanniella (c. 44 species) is the largest podostemoid genus in Africa. This paper deals with the structure and development of the Ghanaian species Ledermanniella bowlingii (J.B. Hall) C. Cusset (subgenus Ledermanniella). Characters typical for L. bowlingii include: green ribbon-like roots with exogenous lateral roots and endogenous shoots up to 120 cm; most leaves 3–7 times forked, with intrapetiolar stipules; flowers solitary or in clusters, borne on elongate stems or directly on roots; each flower bud inverted within a spathella; flowers unistaminate; tricolpate pollen in dyads; ovary mainly unilocular but bilocular at the base due to a rudimentary septum; mature capsule with eight ribs, 1.0–1.8 mm long, containing 12–34 seeds, dehiscing by two equal valves; capsule stalk with pedicel (10 mm) and gynophore (2 mm); silica bodies absent in all plant parts. Several characters of L. bowlingii are described here for the first time. The paper shows that accurate morphological analyses of African Podostemaceae are badly needed. Received September 30, 2002; accepted November 20, 2002 Published online: March 24, 2003     

Consolidated plasmid Design for Stabilized Heterologous Production of the complex natural product Siderophore Yersiniabactin

Yersiniabactin (Ybt) is a hybrid polyketide-nonribosomal complex natural product also known as a siderophore for its iron chelation properties. The native producer of Ybt, Yersinia pestis, is a priority pathogen responsible for the plague in which the siderophore properties of Ybt are used to sequester iron and other metal species upon host infection. Alternatively, the high metal binding properties of Ybt enable a plethora of potentially valuable applications benefiting from metal remediation and/or recovery. For these applications, a surrogate production source is highly preferred relative to the pathogenic native host. In this work, we present a modification to the heterologous Escherichia coli production system established for Ybt biosynthesis. In particular, the multiple plasmids originally used to express the genetic pathway required for Ybt biosynthesis were consolidated to a single, copy-amplifiable plasmid. In so doing, plasmid stability was improved from ~30% to ≥80% while production values maintained at 20–30% of the original system, which resulted in titers of 0.5–3 mg/L from shake flask vessels.     

LAITOR - Literature Assistant for Identification of Terms co-Occurrences and Relationships

Background  

Biological knowledge is represented in scientific literature that often describes the function of genes/proteins (bioentities) in terms of their interactions (biointeractions). Such bioentities are often related to biological concepts of interest that are specific of a determined research field. Therefore, the study of the current literature about a selected topic deposited in public databases, facilitates the generation of novel hypotheses associating a set of bioentities to a common context.     

An error in the typification of Aristolochia watsoni Wooton and Standley

Aristolochia watsoni Wooton and Standley is shown to be the correct name forA. porphyrophylla Pfeifer, andA. lassa I. M. Johnst. the correct name forA. watsoni, sensu Pfeifer.