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Biomedical subjects

A V Bocharov

Publications and source records attributed to A V Bocharov.

At least 19 recordsLinked to original sources
PubMed2001

Characterization of a 95 kDa high affinity human high density lipoprotein-binding protein.

A new human 95 kDa high density lipoprotein (HDL)-binding protein (HBP) corresponding to a high affinity HDL-binding site with K(d) = 1.67 microg/mL and a capacity of 13.4 ng/mg was identified in human fetal hepatocytes. The HDL binding with the 95 kDa HBP plateaus at 2.5-5 microg/mL under reducing and nonreducing conditions. The association of HDL(3) with the 95 kDa HBP plateaued in 15-30 min while dissociation was complete in 30 min. HDL(3), apoA-I, and apoA-II were recognized by the 95 kDa HBP while low density lipoproteins (LDL) and tetranitromethane-modified HDL were not. The 95 kDa HBP predominantly resides on the surface of cells since trypsin treatment of HepG2 cells eliminated nearly 70% of HDL binding. All studied human cells and cell lines (HepG2, Caco-2, HeLa, fibroblasts, SKOV-3, PA-I) demonstrated the presence of the 95 kDa protein. Both RT-PCR and Western blotting for HB-2/ALCAM were negative in human fetal hepatocytes while Gp96/GRP94 was clearly differentiated from the 95 kDa HBP by two-dimensional electrophoretic mobility. Moreover, deglycosylation of HepG2 membrane preparations did not affect either HDL binding to the 95 kDa HBP or its size, while in contrast it affected the molecular weights of HB-2/ALCAM and SR-BI/CLA-1. We conclude that the 95 kDa HBP is a new HDL receptor candidate widely expressed in human cells and cell lines.

Activated-Leukocyte Cell Adhesion Molecule↗
PubMed2001

Apolipoprotein specificity for lipid efflux by the human ABCAI transporter.

ABCAI, a member of the ATP binding cassette family, mediates the efflux of excess cellular lipid to HDL and is defective in Tangier disease. The apolipoprotein acceptor specificity for lipid efflux by ABCAI was examined in stably transfected Hela cells, expressing a human ABCAI-GFP fusion protein. ApoA-I and all of the other exchangeable apolipoproteins tested (apoA-II, apoA-IV, apoC-I, apoC-II, apoC-III, apoE) showed greater than a threefold increase in cholesterol and phospholipid efflux from ABCAI-GFP transfected cells compared to control cells. Expression of ABCAI in Hela cells also resulted in a marked increase in specific binding of both apoA-I (Kd = 0.60 microg/mL) and apoA-II (Kd = 0.58 microg/mL) to a common binding site. In summary, ABCAI-mediated cellular binding of apolipoproteins and lipid efflux is not specific for only apoA-I but can also occur with other apolipoproteins that contain multiple amphipathic helical domains.

ATP Binding Cassette Transporter 1↗
PubMed2000

Heat shock protein 60 is a high-affinity high-density lipoprotein binding protein.

A new 55-kDa HDL/apolipoprotein binding protein was demonstrated in plasma membrane preparations of the human cell lines and primary cultured hepatocytes. Analysis of specific binding by ligand immunoblots of HDL, apoA-I, and apoA-II to a partially purified 55-kDa PA-I plasma membrane preparation demonstrated a K(d,HDL) = 50 nM (10 microg/ml), K(d,apoA-II) = 20 nM (0.4 microg/ml), and K(d, apoA-I) = 330 nM (10 microg/ml). Following preparative SDS-PAGE electrophoresis of a plasma membrane preparation isolated from human PA-I cells, fractions with apoA-II binding activity were collected, concentrated, and subjected to two-dimensional electrophoresis. Internal microprotein sequencing of the 55-kDa protein band revealed the binding protein as being heat shock protein 60 (hsp60). The hsp60 monoclonal antibody LK-1 blocked apoA-II binding to the 55-kDa HBP preparation. In summary, these results provide a potential mechanism to explain the known association between immunity developed against hsp60 and the development of atherosclerosis.

Amino Acid Sequence↗
PubMed1995

Glucocorticoids upregulate high-affinity, high-density lipoprotein binding sites in rat hepatocytes.

Glucocorticoid hormones (GL) regulate high-density lipoprotein (HDL) plasma concentrations by increasing synthesis and secretion of HDL by the liver. However, little is known about the effect of GL on the uptake and processing of HDL by hepatocytes (HEP). To investigate this question, we studied the effects of dexamethasone (DEX) on the expression of high-affinity HDL-binding sites via the specific binding and internalization of iodine-labeled apolipoprotein E (apo E)-free HDL3 in a culture of rat HEP. Specific binding and internalization of HDL3 decreased by 60% in cells cultured in the absence of DEX for 48 hours. At concentrations of 10(-7) and 10(-5) mol/L, DEX prevented the decrease, maintaining specific binding and internalization versus the control level (at 24 hours). HDL-binding sites with a Kd of 20 micrograms/mL were revealed on the surface of cultured HEP. HEP demonstrated a greater binding capacity in the presence of DEX at concentrations of 10(-7) and 10(-5) mol/L (125 v 45 ng/mg cell protein). The effect of the hormone has demonstrated to be dose-dependent at concentrations between 10(-9) and 10(-7) mol/L, leveling off at 10(-7). Higher concentrations did not induce a further increase in specific binding and internalization. Withdrawal of the hormone from culture medium was associated with a decrease in specific binding of the ligand by 60% in the following 24 hours. To investigate the effect of glucocorticoid deficiency on liver uptake of HDL in vivo, specific binding and internalization were studied in a culture of HEP isolated from adrenalectomized rats (AER) at 2 hours after seeding.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenalectomy↗
PubMed1992

Evidence for direct action of testosterone on rat liver cells: in vivo and in vitro induction of unusual estrogen-binding protein.

We demonstrate that on the rat liver, testosterone (T) induced differentiated functions and enhanced unusual estrogen-binding protein (UEBP) content through mechanisms dependent on cell activation by androgens, the presence of growth hormone (GH) and the hormonal status of the animal. To determine whether liver cells are a target for androgens, we measured T effects on UEBP in gonadectomized adult male and female rats in vivo and in vitro. In ovariectomized rats, T increased 8- to 9-fold UEBP levels that remained constant during 10 days. Also in vitro, using hepatocytes from ovariectomized rats, T alone increased UEBP levels 3-fold in a dose-response pattern. Combining a fixed low dose of GH with different concentrations of T increased UEBP 2-fold above T alone. Whereas GH alone had no effects in ovariectomized rats, hepatocytes were responsive to GH, in a dose dependent pattern that was abolished when T was used together with GH. On the other hand, T alone had no effect in hypophysectomized-ovariectomized animals. The latter group was rendered T responsive after the simultaneous injection of GH with T that increased UEBP content 6.6-fold in vivo. Castrated males revealed a marked responsiveness to T and GH in vivo and in vitro, when added separately or in combination. The results obtained suggest a complex regulatory system and we conclude that T acts directly on rat liver as: (1) an inducer of sex differentiation; and (2) a regulator of UEBP production in males. In addition, liver regeneration studies in castrated-hypophysectomized males revealed the UEBP phenotype in daughter cells in the absence of treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

In vivo and in vitro estimations of the direct effect of estrogen on rat hepatocytes tested by the changes in the unusual estrogen-binding protein content.

The direct effect of estradiol (E2) on the hepatocytes of mature male rats has been examined by measuring the changes in the unusual estrogen-binding protein (UEBP) content and parallel measuring the level of liver estrogen receptors (ER). The content of UEBP (NUEBP) and ER (NER) in the liver were determined using the quantitative methods for differential specific determination of the E2-binding sites of these proteins. It has been shown that the administration of E2 in vivo induced a considerable decrease in hepatic NUEBP not only in intact males, but also in hypophysectomized males during the initial period after the operation (when the content of hepatic ER was still high) and produced no effect in hypophysectomized males during the later period (when liver ER were depleted). Repeated administration of human growth hormone (hGH) (twice a day) resulted in a considerable increase in NER in hypophysectomized males and restored the sensitivity to the subsequent inhibitory effect of E2 on UEBP. We also used rat hepatocytes after a 4-day primary culturing. These cells had a stable morpho-functional status, high ER level, and sex-differentiated UEBP content. Culturing of mature male rat hepatocytes in the medium containing E2 at concentrations close to physiological levels (10(-10)-10(-7) M) decreased NUEBP in a dose-dependent manner. Hexestrol (10(-7) M) but not cholesterol (10(-5) M) also exhibited a direct effect on NUEBP in cultured rat hepatocytes. The effect of E2 was reversible: statistically significant increase in NUEBP was observed 3 days after 10(-9) M E2 had been removed from the culturing medium. It was concluded that hepatocytes may be a primary target for E2 under physiological conditions and that GH may modulate the direct effect of E2 at the hepatic level by modifying the content of liver ER.

Animals↗
PubMed1990

[The effect of androgens and somatotropic hormone on the expression of the level of special estrogen-binding protein in the hepatocytes].

The possibility of direct androgen determination of high unusual estrogen-binding protein (UEBP) level in female rat hepatocytes to the level typical to the males was studied. The direct effect of androgen (A) on the UEBP content in hepatocytes of ovariectomized female rats was shown by estimation in vivo and on hepatocyte culture. It has been revealed that the permissive action of growth hormone (GH) is necessary for normal expression of direct androgen effect. The latter has been stable after cessation of hormone action. High concentration of GH was found to possess positive regulatory effect on the UEBP in hepatocytes of ovariectomized rats. Effect of GH quickly disappeared after hormone withdrawal and was under negative regulation by physiological concentrations of A. It was concluded that A owing to its direct action together with permissive influence of GH is capable of determining stable expression of male phenotype of the UEBP level in hepatocytes of females.

Animals↗
PubMed1990

[Use of hepatocytes cultured in microcarriers for correction of acute hepatic insufficiency].

The ability of hepatocytes cultured on Biosilon microcarriers to secrete albumin and to conjugate bilirubin were examined for the purpose of developing an artificial liver support system. Cultured hepatocytes were able to synthesize 100-120 micrograms albumin per 10(5) cells in 24 hours and to conjugate about 20 micrograms/hr of bilirubin for at least 5 days. Rats with liver failure caused by i.p. injection of CCL4 or D-galactosamine were subjected to hemosorption via minicolumns containing 2 ml of Biosilon microcarriers with 40 X 10(6) cultured hepatocytes. The procedure was performed 20-24 h after hepatotoxins injection and lasted for 3 h at a flow rate of 60 ml/h. This reduced mortality from 100% to 20% after 48% and to 40% after 7 days in case of CCl4 and from 100% to 40% after 48 h and 7 days in case of D-galactosamine. Our results suggest that hepatocytes cultured on microcarriers may be efficiently applied to correction of fulminant hepatic failure caused by different hepatotoxins.

Acute Disease↗
PubMed1989

[Estimation of a direct regulatory effect of estrogens on hepatocytes, evaluated according to the change in the level of free estrogen-binding protein in primary cell culture].

Male rat hepatocyte cultures have been obtained. The culturing hepatocytes had a stable level of some morphological and functional properties. A high level of estrogen receptors (ER) and E2-sensitive unusual estrogen-binding protein (UEBP) was found. A direct dose-dependent inhibiting effect of physiological (10(-10)-10(-7) M) concentrations of E2 on UEBP content was established in cell cultures incubated with the hormone for 3 days. Hexestrol (but not cholesterol) was found to exert a direct inhibiting effect. The inhibiting effect of E2 (10(-9) M) was observed after a 24 hour incubation of hepatocytes with the hormone but was less pronounced. In this case a significant increase in UEBP concentration in hepatocytes was noted 72 hours after the removal of E2. It is concluded that physiological concentrations of E2 can exert a direct regulatory influence on certain functions of culturing hepatocytes acting via hepatocyte ER.

Animals↗
PubMedDate not supplied

[Experience with endovascular occlusion of cerebrovascular aneurysms by means of microspirals].

The paper summarizes the outcomes of endovascular treatment of 42 patients (19 males and 23 females) aged 24 to 68 years who had cerebrovascular aneurysms, 7 of them were operated on in the acute phase of subarachnoidal hemorrhage. There were small [n = 27 (61.4%)], large [n = 14 (31.8%)], and giant [n = 3 (6.8%)] aneurysms. According to their site, aneurysms were found in the internal carotid [n = 22 (50%)], the middle cerebral artery [n = 2 (4.5%)], the anterior cerebral artery-anterior communicating artery [n = 10 (22.7%)], the basilar artery [n = 9 (20.5%)], and the vertebral artery [n = 1 (2.3%)]. MDS tungsten and platinum miscospirals (Balt, France) were employed for aneurysmal occlusion. Twenty seven (61.4%) aneurysms were totally and subtotally closed by means of microspirals. Partial occlusion of the aneurysmal cavity was achieved in 12 (27.2%) cases. There were poor results associated with spiral migration into the carrying vessel in 5 patients: an increase in aneurysmal volumes occurred in 3 patients and in 2 patients with partially occluded giant aneurysms within up to a year. Three patients died. Angiographical control was exercised in 12 patients at months 6 to 18. The analysis of long-term results indicated that the aneurysms initially totally closed failed to be recanalized later on (8 patients). With subtotal or partial occlusion, there was a change in the position of spiral coils in the aneurysmal cavity, namely, their displacement to the bottom and an increase in the dimension of a functioning aneurysmal part (2 patients). The use of microspirals for occlusion of cerebrovascular aneurysms is a low-traumatic and effective treatment. The best results were obtained with the occlusion of small and large aneurysms with their well-defined neck.

Adult↗