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I Christov

Publications and source records attributed to I Christov.

6 recordsLinked to original sources
PubMed1995

Non-invasive electrogastrography. Part 1: Correlation between the gastric electrical activity in dogs with implanted and cutaneous electrodes.

Experiments were made on dogs with bipolar silver ball-shaped electrodes chronically implanted on the muscle wall of the stomach. The electrical activity of the gastric muscle wall (electrogastromyogram-EGMG) was characterized by slow potential changes during the quiescent period of the migrating myoelectric complex (MMC) and bursts of spike potentials during the activity period of MMC. Cutaneous (surface) electrodes were placed on the abdominal wall. Waves with a rhythm of 4.5-5 cpm were led off by the cutaneous electrodes (electrogastrogram-EGG), simultaneously with the EGMg. The bursts of spike potentials with the slow gastric potentials in the EGMG corresponded to an increase of the amplitude of the waves in the EGG. Good correlation was found between the number and frequency of spike potentials in a group and the wave amplitude in the EGG. EGG recorded on an electrogastrograph designed by us was characterized by low-amplitude waves corresponding to the slow waves during the period of quiescence of MMC and high-amplitude waves corresponding to the bursts of spike potentials during the activity period of MMC. Therefore it is possible to determine the MMC of the stomach by the changes in the amplitude of the waves in the EGG.

Action Potentials↗
PubMed1995

Non-invasive electrogastrography. Part 2. Human electrogastrogram.

The electrical activity of human stomach muscle wall-electrogastrogram (EGG), was led off by surface (cutaneous) electrodes placed on the abdominal wall and recorded on an electrogastrograph. A method for complete elimination of the cardiac artefact was elaborated and successfully implemented. It consists of a preliminary elimination of the QRS complex, based on its higher amplitude and slope. The eliminated intervals were replaced by linear segments. A subsequent low-pass filtering allowed to obtain a high quality EGG signal. The electrical activity of the stomach of healthy volunteers was characterized by waves with a frequency of 3.35 +/- 0.09 cpm during the quiescent periods and 2.99 +/- 0.14 cpm during the activity periods of the migrating myoelectrical complex (MMC). Bearing in mind the correlation between the bursts of spike potentials with the slow waves in the dog EGMG and the high-amplitude waves, characterizing the periods of activity in the dog EGG, we can better differentiate the periods of quiescence and activity by the amplitude of the waves. The wave amplitude during periods of quiescence was 81.13 +/- 20.61 microV, significantly different from the wave amplitude during periods of activity being 164.74 +/- 43.34 microV (n = 7). Thus with this method in visual inspection it is possible to identify MMC of the human stomach by the changes in the amplitude of the waves in the EGG.

Action Potentials↗
PubMed1992

A stable line of turkey bone marrow cells transformed by the myelocytomatosis virus strain MC31. Ultrastructural characteristics and localization of the DNA replication sites.

Attempts were made to characterize cells of the LSTC-SF2 line by scanning electron microscopy and transmission electron microscopy on the ultrastructural level. The virus-transformed cells are of oval, slightly elongated shape with an undulating surface. The cell nucleus is well outlined, poor in heterochromatin but with a strongly developed nucleolus. The cytoplasm is not rich in organelles except for an abundance of mitochondria with dense granules that are often found in them. With high-resolution autoradiography the DNA synthesis sites were identified mainly in proximity to the nuclear membrane and in the perinuclear spaces. The cells under study can be regarded as immature forms of the blood series and most likely as precursors of cells of the granulocyte or monocyte series.

Animals↗
PubMed1978

Delayed hypersensitivity reactions in patients with breast cancer.

Fifty six patients with metastatic cancer of the breast (stage IV) were treated with Cyclophosphamide, 5-Fluorouracil and Cyclophosphamide + 5-Fluorouracil. Tests for delayed hypersensitivity to homologous tumor antigen before treatment were positive in 83.9% and negative in 16.1%. Response to DNCB was positive before treatment in 51.8% and negative in 48.2%. Following chemotherapy the skin reaction, to homologous tumor antigen remained positive, only in 12.6% and negative in 87.4%. The reaction of DNCB remained positive after treatment only in 17.8%. In the remaining 82.2% suppression of the reaction occurred. These data show that chemotherapy may suppress, to a certain excent, immune responses. It is established that among patients who have shown a positive reaction to homologous tumor antigen 55.3% of all cases have displayed objective response to the treatment, and among these with negative skin reactions objective responses were observed in 22.22% of all cases. In patients with positive DNCB reactions objective responses were observed in 79.3% and among the negative ones--in 37.4%.

Adult↗