Nonlocal branches of cycles, bistability, and topologically persistent mixed mode oscillations.

A possible mechanism for generating mixed mode oscillations is based on an appropriate S-shaped structure, which graphs the relation between the parameter and the collection of periodic oscillations existing for a particular parameter value in the product of parameter and phase spaces. This natural scenario should be supplemented by simple and constructive criteria of existence, and methods of localization, of such S-shaped structures. These criteria are the main focus of the paper.

Mesoderm-inducing factor from bovine amniotic fluid: purification and N-terminal amino acid sequence determination.

Bovine amniotic fluid contains a protein capable of inducing mesoderm formation from animal cap cells isolated from Xenopus laevis embryos at the late blastula stage. The procedure for purification of this protein is described and includes the following steps: CM-cellulose cation-exchange chromatography, chromatography on hydroxylapatite, reverse-phase hplc, size exclusion hplc, and a second reverse-phase hplc. A partially purified preparation of a mesoderm-inducing factor with high mesoderm-inducing activity was thus obtained. SDS polyacrylamide gel electrophoresis with subsequent transfer of proteins onto Immobilon membrane was used to obtain the protein in pure form. The membrane was cut, the proteins eluted, and each fraction tested for mesoderm-inducing activity. The mesoderm-inducing activity corresponded to a protein of molecular mass 25 kDa (in nonreducing conditions) consisting of two identical polypeptides connected by disulphide bonds. The purified factor, at concentrations of 0.3-1 pmol ml-1, induced development of notochord and muscle cells and, at lower concentrations, mesenchyme and blood cells. The twenty N-terminal amino acid residues of the protein were sequenced and found to be identical to those of the N-terminus of the beta A-chain of inhibin and activin, known regulators of FSH secretion by pituitary cells. The beta A-chain is homologous with the transforming growth factor-beta family of proteins. On the basis of the estimated molecular mass of the mesoderm-inducing factor and its N-terminal sequence it is suggested that the protein is activin or a related protein.

[Normal indices of left ventricular function assessed by using computer technology]. / Normal'nye pokazateli funktsional'nogo sostoianiia levogo zheludochka, otsenennye s primeneniem komp'iuternoi tekhniki.

While analysing ventriculograms of 18 persons without any cardiovascular pathology 3 "independent" research workers (to exclude a subjective factor in the appraisal of the left ventricle contours) have developed normal indicators of the total and regional contractility of the left ventricle. The data obtained with the use of angiographic and computer-aided techniques of the recent generation and machine analysis employing unpaired statistics can be recommended for application as normal indicators during the performance of different hemodynamic studies.

[The dipyridamole test in the diagnosis of ischemic heart disease in women]. / Proba s dipiridamolom v diagnostike ishemicheskoi bolezni serdtsa u zhenshchin.

Bicycle ergometry and the dipyridamol test were performed in 25 females with coronary artery stenosis and 42 with unchanged coronary arteries (according to the coronarography data). The sensitivity of the dipyridamol test was 80% at its specificity was 78% according to the electrocardiographic data that correlated well with those of bicycle ergometry. The dipyridamol test can be used for examining females with suspected coronary heart disease.