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Biomedical subjects

A Ivanov

Publications and source records attributed to A Ivanov.

At least 91 records · Page 5Linked to original sources
PubMed1991

Nerve cells of Drosophila Notch mutant are differentiated inside amphibian brain: a new approach for the analysis of genetic control of nerve cell differentiation.

Fragments of the neural primordium of a new Notch mutant of Drosophila melanogaster produced in our laboratory were transplanted into the neural tube of embryos of 4 amphibian species (caudate and ecaudate) immediately after completion of neurulation. The grafts were identified by using a light microscope, scanning electron miscroscope, and in situ hybridization with mobile genetic elements of Drosophila and fluorescent dyes as markers. As has been shown, Drosophila nerve cells survive and differentiate inside the neural tube of amphibian embryos. The grafts increase in size by twentyfold and the cell proliferation zones are retained during the period of six months. Differentiated cells of the graft formed axon-dendritic contacts with recipient cells and penetrated into the organisms' brain structures. The effect of Drosophila transplants proved to be different for caudate and ecaudate amphibians. The presence of the graft accelerated the development of Xenopus laevis and it also affected their behavior. This approach can be very useful for the study of genetic basis of development and behavior.

Animals↗
PubMed1990

Purification of phospholipase-C from Bacillus cereus by affinity chromatography on 2-(4-aminophenylsulphonyl)ethyl-cellulose.

A new method for the purification of phospholipase-C (phosphatidylcholine cholinephosphohydrolase, EC 3.1.4.3) from Bacillus cereus has been developed, based on its affinity to 2-(4-aminophenylsulphonyl)ethyl derivative of beaded cellulose. The enzyme was adsorbed on the affinity sorbent through a site(s) that was clearly distinct from its catalytically active site, because it was still active in the immobilized state. A possible role of enzyme-inhibitor interaction in enzyme binding to the ligand used is discussed.

Adsorption↗
PubMed1990

Pigment types in selected color genotypes of Asiatic sheep.

The types and amounts of pigments in fibers from variously colored Tajik, Hissar, and Caracul sheep were determined by three methods: high-performance liquid chromatography, electron spin resonance spectroscopy, and light microscopic evaluation of melanosomes. In both dominant and recessive black lambs the color is due to eumelanin pigment. Brown and red phenotypes are the result of interaction of AWt and EBl, EBr, or EY alleles, and these colors are caused by mixtures of eumelanin and pheomelanin in varying ratios. The HPLC and ESR measurements detected these differences in melanin type, while direct characterization of melanosomes generally failed to distinguish between melanin type or relative ratio of melanin type.

Animals↗
PubMed1989

Ongoing electrical activity of superior cervical ganglion cells in mammals of different size.

The ongoing synaptic activity of superior cervical ganglion cells in adult mammals was examined in situ by intracellular recording in anesthetized mice, hamsters, rats, guinea pigs, and rabbits. The proportion of neurons exhibiting subthreshold and suprathreshold synaptic activity during a standard period of observation was least in a small mammal like the mouse (30%), intermediate among neurons of mammals of intermediate size such as the hamster and rat (48% and 45%, respectively), and greatest in the largest animals in the series, the guinea pig (89%) and rabbit (91%). Ganglion cells in all species fell silent after transection of the cervical trunk. The average frequency of synaptic activity among tonically active cells also increased with animal size, being least in the mouse (1.0/second) and greatest in the rabbit (6.4/second). This variation of ongoing synaptic activity in sympathetic ganglion cells may reflect the demands of progressively larger peripheral targets on relatively fixed populations of autonomic neurons.

Action Potentials↗
PubMed1989

[Typical and atypical resections of the liver with 2 clinical cases].

The development of resection liver surgery is discussed in a historical aspect. The basic topographic-anatomical guidelines, indications and different techniques of performance of atypical and typical liver resection are given. Two clinical cases of spacious liver resections are reported: resection of large hydatid cyst of the left lobe in a 16 years old girl and two liver resection for liver cystadenocarcinoma in a 25 years old woman. The advantages of applying top technical achievements in liver resection surgery are pointed out.

Adolescent↗
PubMed1987

Occurrence and distribution of Hantavirus in wild living mammals in Belgium.

Small mammals were screened for the presence of antibodies to Hantaan virus (HTN) and Hantavirus (HV) antigen in Belgium. Antibody and antigen-positive animals were found in different parts of the country. One insectivore and five rodent species were found positive. The highest prevalence of infection was found in the bank vole (Clethrionomys glareolus). A relation between infected animals and wet habitats was observed. It was obvious that in bank vole the likelihood of infection increased with age.

Age Factors↗
PubMed1983

[Prevention of colibacillosis in pigs with CA-80 polyvalent vaccine].

A live polyvalent Escherichia coli vaccine, CA-80, has been produced and adopted into practice in this country. It contains a definite amount of immunogenic agents, such as the K 88 antigen, the LT and ST toxins, the K 99 antigen, and an enteroinvasive strain. Laboratory and field experiments have shown that the immunization of sows with newborn sucking pigs leads to the drop of mortality rate from 8.48 to 1.84 per cent as well as to the rise of the average liveweight by 400 to 600 g on the 30th day following birth. Besides, the live vaccine has been shown to act protectively both against the homologous and heterologous enterotoxigenic strains of Escherichia coli and against E. coli strains with a K 99 antigen.

Animals↗
PubMed1980

[E. coli strain K88+ isolated from pigs].

A 151 E. coli strains isolated from diarrhea-affected pigs were studied for the presence of the antigen K88. The established strains positive for this antigen, belong to the serogroups: O149, O141, O139, O138, O18 and one strain of nondemonstrated O-serogroup. All positive strains produce antigen K88 on cultivation at 37 degrees C utilizing raffinose and forming gas. The same strains do not produce antigen K88 when cultivated at 18 degrees C.

Animals↗
PubMed1978

[Pharmacological and toxicological studies of novoolean].

A toxicologic study and some pharmacologic investigations were carried out with the novobiocin salt of oleandomycin, formulated as novoolean. The LD50 of the of the preparation for i/m application to mice proved equal to 1500, and to rats--1800 mg per kg of body weight. For oral introduction the average lethal dose for mice amounts to 3250 mg/kg. At such route of application on deaths were observed in rats after the administration of 5 000 mg/kg. A 30-day treatment via i/m application to rats of 180 mg/kg (which is equal to one tenth part of LD50) did not lead to changes in the growth, blood picture, and a number of clinical and biochemical indices of the blood and urine; there were no changes in the development and the structure of the viscera as well as the reproductive capacity of the test animals. Electron-microscope studies with rats treated in the same period with 360 mg/kg (one fifth of the LD50 value) revealed certain injuries of the liver kidneys. With cats the venous infusion of the preparation at rates of up to 15 mg/kg showed no changes in the blood pressure and the rhythm and pulse rate, and the addition of novoolean to the nutrient solution in concentrations of up to 100 mg/cu. cm did not influence the tonus and the motor function of isolated (after Magnus) sectioned portions of the small intestine of rabbits and guinea pigs.

Animals↗