Sinusoids--elements of the circulatory bed of the human heart

The literature concerning the problems of myocyrdial sinusoids has been analysed and morphological investigation of 98 human hearts has been performed. As demonstrates the comparison of the literature data, the term "sinusoid" in the human heart is applied to different structures. In some cases--to designate dilated areas of the venous part of the blood bed in the ventricular walls, in others--"hollow spaces", "intercellular spaces" and Vieussens--Thebesius vessels. Combining methods of intravascular injections and studying serial histological sections, it has been found that the sinusoids--the "hollow spaces", the "intercellular spaces", the "Veussens--Thebesius vessels" present the areas of intertrabcular spaces, which get into the planes of some sections, not being components of the myocardial blood bed. Spatial angioarchitectonics of the sinusoids--dilated areas in the venous part of the myocardial blood bed have been investigated by means of the plastic reconstruction method. It is suggested to apply the term "sinusoids" only to the given parts of the cardiac blood bed.     

Genetic studies of cleavage-initiated mRNA decay and processing of ribosomal 9S RNA show that the Escherichia coli ams and rne loci are the same

We show in the present paper that the cleavages initiating decay of the ompA mRNA are suppressed both in the Escherichia coli ams(ts) strain (originally defined by a prolonged bulk mRNA half-life) and in the me(ts) strain (originally defined by aberrant 9S RNA processing). The temperature-sensitive defects of both these strains are complemented by a recombinant lambda phage containing a genomic segment that carries the putative ams locus. A 5.8 kb fragment from this genomic DNA segment was cloned into a low-copy plasmid and used to transform the ams(ts) and rne(ts) strains. This resulted in growth at the non-permissive temperature and a reoccurrence of the cleavages initiating decay of the ompA mRNA. Deletion analyses of this 5.8 kb fragment indicated that the putative ams open reading frame could complement both the Ams(ts) and the Rne(ts) phenotype with regard to the ompA cleavages. In addition we showed that the ams(ts) strain suppresses 9S RNA processing to 5S RNA to the same extent as the rne(ts) strain, and that the rne(ts0 strain has a prolonged bulk mRNA half-life, as was reported for the ams(ts) strain. Therefore we suggest that ams and rne reflect the same gene locus; one which is involved both in mRNA decay and RNA processing. We discuss how this gene locus may related to the previously characterized endoribonucleolytic activities of RNase E and RNase K.     

Growth Phase-Regulated Induction of Salmonella-Induced Macrophage Apoptosis Correlates with Transient Expression of SPI-1 Genes

Invasive Salmonella has been reported to induce apoptosis in a fraction of infected macrophages within 2 to 14 h from the time of infection by a mechanism involving the type III secretion machinery encoded by the Salmonella pathogenicity island 1 (SPI-1). Here, we show that bacteria in the transition from logarithmic to stationary phase cause 90% of the macrophages to undergo phagocytosis-independent, caspase-mediated apoptosis within 30 to 60 min of infection. The ability of Salmonella to induce this rapid apoptosis was growth phase regulated and cell type restricted, with epithelial cells being resistant. Apoptosis induction was also abrogated by disruption of the hilA gene (encoding a regulator of SPI-1 genes) and by the expression of a constitutively active PhoPQ. hilA itself and a subset of SPI-1 genes were transiently expressed during aerobic growth in liquid medium. Interestingly, however, hilA was found to be required only for the expression of the prgH gene, while sipB, invA, and invF were expressed in a hilA-independent manner. The expression of SPI-1 genes and the secretion of invasion-associated proteins correlated temporally with the induction of apoptosis and are likely to represent its molecular basis. Thus, growth phase transition regulates the expression and secretion of virulence determinants and represents the most efficient environmental cue for apoptosis induction reported to date.     

Topography and parameters of the intertrabecular spaces of the heart ventricles in man and laboratory animals

The heart of the man, dog, cat and rabbit have been investigated using biometry and corrosive methods. In the horizontal sections the volume of the intertrabecular spaces (IS) of the ventricles has been estimated and the "coefficient of the myocardial sponginess" has been calculated as the ratio of the cavities volume to the myocardial volume. In the corrosive casts of the ventricular cavities the deviation angles of the IS casts from the axial line along the afferent and deferent tracts have been measured. Differences in manifestation of the IS in the hearts of the mammals studied have been revealed. The IS are best pronounced in the human heart, less in the dog heart and still less in the cat and rabbit hearts. For all the hearts studied predominance of the volume of the IS in the right ventricle is specific. The deviation angle of the IS casts from the axial line along the afferent tract increases from the cardiac basis towards its apex, while the deviation angle of the IS along the deferent tract decreases from the apex towards the basis. The functional predisposition of the IS is supposed to consist in providing systolic reserves of the cardiac ventricular cavities. The results of the mathematical analysis of the changes in the cast deviation angles of the IS along the afferent and deferent tracts demonstrate their role in twisting and acceleration of the blood stream in the systolic phase and slowing down of the blood stream in the diastolic phase.