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Biomedical subjects

M Fainaru

Publications and source records attributed to M Fainaru.

At least 73 records · Page 4Linked to original sources
PubMed1980

Inner ear involvement in Behçet's disease.

Ten of 16 patients with Behçet's disease complained of hearing disturbances (62%), and six of them had vertigo (37%). Detailed audiologic and vestibular examinations revealed both cochlear and vestibular abnormalities in those patients. The labyrinth involvement may be ascribed to vasculitis, which is the basic pathologic lesion in Behçet's disease. This inner ear involvement is a late complication of this disease, appearing almost a decade after the initial manifestations.

Adolescent↗
PubMed1980

Recurrent hepatitis caused by two viruses acquired simultaneously during blood transfusion.

We here report 2 patients who have acquired two consecutive episodes each of acute hepatitis, within 6 months after blood transfusion. The clinical and biochemical course was typical of recurrent acute viral hepatitis, and the patients recovered completely after each episode. The first infection was probably caused by non-A, non-B hepatitis virus, whereas the second episode was caused by hepatitis B-virus. Thus, in addition to the absence of cross-immunity between hepatotrophic viruses, one may simultaneously acquire more than one virus without apparent interference.

Aged↗
PubMed1980

The role of different albumin preparations on production of human plasma lipoprotein-like particles in vitro.

Because we found apoprotein contamination of some high-grade commercial albumins, we studied this effect on formation of lipoprotein-like particles during lipolysis of human very low density lipoprotein (VLDL) in vitro. After a 1-hr incubation with purified bovine milk lipoprotein lipase, over 98% VLDL triglyceride was hydrolyzed in the presence of either albumin B (apoprotein-rich) or albumin C (apoprotein-poor), with a weight ratio of albumin to triglyceride of 60 to 1. Lipoproteins of density < 1.019 g/ml ("IDL"), 1.019 to 1.063 g/ml ("LDL"), and 1.063 to 1.21 g/ml ("HDL") were then isolated by ultracentrifugation. Recovery of non-triglyceride VLDL constituents in "IDL" and "LDL" was similar for albumin B or albumin C. "LDL" was the major catabolic product of in vitro VLDL lipolysis independent of the albumin used. The yield of "HDL," however, was 5- to 6-fold greater with albumin B. All lipoproteins produced with albumin B were richer in phospholipid, apoproteins C and A-I, relative to lipoproteins produced in the presence of albumin C. With albumin B, cholesterol/phospholipid molar ratios were <1 in all in vitro produced lipoproteins, but were >1 with albumin C. All these differences can be ascribed to the presence in albumin B of 0.2 mg apoprotein A-I/g albumin and 1.8 mg phospholipid/g albumin; these components were not detected in albumin C. Thus, two thirds of "HDL" recovered with VLDL lipolysis in the presence of albumin B can be accounted for by albumin itself and only one third from constituents of VLDL. Adding equivalent amounts of both apoproteins removed from albumin B and phospholipid to albumin C markedly decreased the disparities in results but addition of each alone did not. These results prove "inert" albumins serve other than as fatty acid and lysolecithin acceptors in in vitro model systems, and do influence formation of lipoproteins during in vitro VLDL catabolism.-Deckelbaum, R. J., T. Olivecrona, and M. Fainaru. The role of different albumin preparations on production of human plasma lipoprotein-like particles in vitro.

Albumins↗
PubMed1979

The role of lysophosphatidylcholine and apolipoprotein A in the cholesterol-removing capacity of lipoprotein-deficient serum in tissue culture.

Lipoprotein-deficient serum (d greater than 1.21 or 1.25 g/ml fraction) is commonly used to deplete cellular cholesterol from cultured cells and presently we have studied some of the potential promoters of this process. Although serum albumin is the main protein component of the fraction, its cholesterol-removing capacity was quite limited, even in the presence of lysophosphatidylcholine, which is the major phospholipid of the d greater than 1.25 g/ml infranatant of serum. On the other hand, apolipoprotein A1 especially when complexed with lysophosphatidylcholine promoted considerable release of cellular cholesterol. The cholesterol-removing capacity of lysophosphatidylcholine alone was related to the fatty acid chain length and was low when the fatty acid chain length was below C-14. The release of cellular cholesterol is not related to shedding of surface glycoproteins and depends on the presence of suitable acceptors in the medium. Such acceptors were presently found in an ultrafiltrate of serum prepared by membrane filtration. It is proposed that in human serum there are low molecular weight protein-phospholipid complexes (less than 100,000), which can cross the capillary endothelial barrier, in preference to lipoproteins, and promote cholesterol removal from peripheral cells.

Adult↗
PubMed1979

A method for studying plasma transport of vitamin D applicable to hypervitaminosis D.

In man, vitamin D is normally transported on a specific binding globulin (DBP) and on lipoproteins. In addition, binding to albumin occurs in the presence of vitamin D excess. Agarose gel electrohoresis was used to study the binding of radioactive vitamin D to plasma proteins in lipoprotein-free plasma (d greater than 1.21 g/ml). This method completely separates DBP from albumin and thus enables the quantification of vitamin D bound to these proteins in various clinical and experimental conditions. The same method can be used to study the transport of other vitamin D metabolites.

Biological Transport↗
PubMed1979

Apolipoprotein A-I synthesis and secretion by cultured human intestinal mucosa.

Cultured human duodenojejunal mucosa was used to study the synthesis and secretion of apoprotein A-I (apoA-I), the major protein constituent of plasma high density lipoproteins. ApoA-I, measured by radioimmunoassay, was secreted continuously into the culture medium over a period of 24 hr. The highest rate was found in the first two hours (34.6 +/- 3.0 ng/mg tissue X hr, mean +/- SE, n = 24). Secretion rate decreased with incubation time, while changes of culture medium increased the rate. ApoA-I secretion was enhanced three- to fourfold by micellar lipid solution and was inhibited by puromycin, ApoA-I synthesis was confirmed by incorporation of 14C-leucine into this apoprotein. The specific activity of apoA-I in medium ultracentrifugal fractions (d less than 1.019 and d = 1.063--1.21 g/ml) was calculated from quantitative data obtained by radioimmunoassay and radioassay of apoA-I separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and found to be about 12 mCi/mmol. These observations indicate that cultured human intestinal mucosa is capable of secreting newly synthesized apoA-I. Organ culture may thus serve as a tool for studying the regulating mechanisms for the synthesis and secretion of this important apoprotein.

Apolipoproteins↗
PubMed1978

Origin and transport of the A-I and arginine-rich apolipoproteins in mesenteric lymph of rats.

Transport of apolipoprotein A-I and argininerich apolipoprotein in mesenteric lymph was examined in rats given constant intraduodenal infusions of saline, glucose in saline, or emulsified fat. Lymph flow in all groups was constant from 5 to 50 hr after beginning the infusions. Lymphatic transport of triglycerides was about 20-fold greater and transport of apoprotein A-I was about twofold greater in fat-infused rats than in the other two groups. In each group transport of apoprotein A-I bore a significant positive relationship to transport of triglycerides. Lymphatic transport of the arginine-rich apoprotein was only 6-12% of that of apoprotein A-I and was more closely related to lymphatic transport of total protein than to that of triglycerides. In fat-infused rats given [(3)H]lysine intraduodenally, about two-thirds of the (3)H in the chylomicron proteins was in apoprotein A-I and only about 1% was in the arginine-rich apoprotein. Estimated specific activity of chylomicron proteins was highest for apoprotein A-I and apoprotein A-IV, and lowest for the arginine-rich apoprotein and proteins of low molecular weight (mainly C apoproteins). In fat-infused rats given constant intravenous infusions of radioiodinated high density lipoproteins from blood plasma, the specific activity of apoprotein A-I in lymph chylomicrons was only about 5% of that of apoprotein A-I in blood high density lipoproteins, indicating that more than 90% of the apoprotein A-I in chylomicrons was synthesized in the intestine. From these and other data it is concluded that both the intestine and liver are significant sources of apoprotein A-I whereas only the liver synthesizes significant amounts of the arginine-rich apoprotein.

Animals↗
PubMed1978

Apoprotein synthesis by human duodenojejunal mucosa.

We tested whether human duodenojejunal mucosa is able to synthesize apoproteins from amino acid precursors because lipoprotein-like particles are visualized by electron microscopy in human absorptive cells and because apoproteins are synthesized by the perfused rat intestine. Duodenojejunal biopsies from 21 normal fasting volunteers were incubated with L-[U-14C]leucine; 15.6 +/- 3.3 nmoles of the [14C]leucine was incorporated into protein by 100 mg wet weight of biopsies during an incubation of 2 hr. No [14C]leucine was incorporated by boiled biopsies. Homogenates of incubated biopsies were fractionated by ultracentrifugation: 43 +/- 2% of the incorporated 14C as found in the d less than 1.006 fraction; 3.2 +/- 0.6%, 8.1 +/- 1.0% and 48 +/- 2% were found to be associated with the d = 1.006 to 1.063, d = 1.063 to 1.25, and d greater than 1.25 fractions, respectively. The specific activity in the d less than 1.006 fraction was 5.6 times greater than that in the other fractions. Of the 14C incorporated into the d less than 1.006 fraction, 10.8, 7.2, and 7.1% were specifically precipitated by rabbit antihuman apoproteins A-I, A-II, and B, respectively. Of the 14C incorporated into the d = 1.006 to 1.063 fraction, 11.3 4.1, and 8.5% were specifically precipitated by rabbit antihuman apoprotein A-I, A-II, and B, respectively. Approximately 5% of the 14C incorporated by the d = 1.063 to 1.25 fractions were precipitated by rabbit antihuman apoprotein A-I or A-II. None of the d less than 1.25 fractions precipitated a significant amount of radioactivity with rabit antihuman apoprotein C-II, or antiarginine-rich apoprotein. None of the antibodies precipitated radioactivity from the d greater than 1.25 fraction. These experiments suggest that human duodenojejunal mucosa is able to synthesize in vitro apoproteins A-I, A-II, and B from amino acid precursors. The specificity of the immunoprecipitates was confirmed by sodium dodecyl sulfate polyacrylamide gel electrophoresis.

Adolescent↗
PubMed1978

Composition of proteins of mesenteric lymph chylomicrons in the rat and alterations produced upon exposure of chylomicrons to blood serum and serum proteins.

Protein composition was determined in mesenteric lymph chylomicrons from fat-fed rats. Among the proteins of intermediate molecular weight, apoproteins A-I and the arginine-rich apoprotein accounted for 31% and 4% of the total protein mass, respectively. Apoprotein B and apoprotein A-IV each accounted for about 10% and proteins of low molecular weight (C apoproteins and apoprotein A-II) accounted for most of the remainder. Apoprotein A-I also accounted for more than 30% of the protein mass of mesenteric lymph lipoproteins of density less than 1.006 g/ml ("small chylomicrons") obtained from rats fed glucose. Aproprotein A-I was partially dissociated from chylomicrons during brief ultracentrifugation. Both the arginine-rich apoprotein and the C apoproteins in rat blood serum were transferred to lymph chylomicrons from fat-fed rats during incubation in vitro. Content of arginine-rich apoprotein, determined immunochemically, increased six-fold when chylomicrons were diluted to a final concentration of 500 mg/dl in blood serum. Upon incubation of chylomicrons in equivalent volumes of ultracentrifugal fractions of serum, the increase of the arginine-rich apoprotein was: very low density lipoproteins, 1.5-fold; high density lipoproteins, 1.8-fold; density fraction greater than 1.006 g/ml, 5.0-fold; density fraction greater than 1.21 g/ml, 11-fold. Content of apoprotein A-I, also determined immunochemically, was not altered appreciably by exposure to serum or its ultracentrifugal fractions, whereas content of C apoproteins, estimated from intensity of staining of the low molecular weight protein component in polyacrylamide gel electropherograms, increased in all cases except for the density fraction greater than 1.21 g/ml. The fractional content of apoprotein A-I in the protein of chylomicrons fell after incubation, whereas that of the arginine-rich apoprotein remained constant or rose substantially. The fractional content of apoprotein A-IV in chylomicron-protein tended to follow that of apoprotein A-I, as judged from polyacrylamide gel electropherograms. Transfer of the arginine-rich and C apoproteins to chylomicrons from blood serum was directly related to the volume of serum in which the chylomicrons were diluted and occurred rapidly at room temperature or at 4 degrees C.

Animals↗
PubMed1977

Radioimmunoassay of arginine-rich apolipoprotein of rat serum.

A double-antibody radioimmunoassay was developed for quantification of rat arginine-rich apolipoprotein in sodium decyl sulfate. Arginine-rich protein, labeled with 125I by the chloramine-T method, had the same chromatographic characteristics on Sephadex G-200 as unlabeled arginine-rich protein and up to 70% of 125I-labeled arginine-rich protein was precipitated by antisera to arginine-rich protein in rabbits. The assay is sensitive at the level of 1-10 ng and has intraassay and interassay coefficients of variation of 5.4 and 6.8%, respectively. The specificity of the assay was established by competitive displacement of 125I-labeled arginine-rich protein from its antiserum by arginine-rich protein and lipoproteins containing this protein, but not by rat albumin or other purified apolipoproteins. Immunoreactivity of rat serum and lipoproteins was complete as demonstrated by comparison with their delipidated form. The accuracy of the immunoassay was further substantiated by comparison with the amount of arginine-rich protein in chromatographic fractions of total apoprotein of very low and high density lipoproteins, and by recovery experiments in ultracentrifugally separated fractions of serum. In contrast to an immunoassay reported previously for rat apo A-I, sodium decyl sulfate was not required for complete immunoreactivity of serum and lipoproteins. The inclusion of sodium decyl sulfate (9 mM final concentration) was necessary, however, for stability of labeled and unlabeled preparations of arginine-rich protein. Content (weight %, means values +/- S.D.), of immunoassayable arginine-rich protein in isolated lipoproteins was 15 +/- 1.5% in very density lipoproteins; 6.8% in low density lipoproteins (1.02 less than d less than 1.04 g/m); 7.1 +/- 0.3% in high density lipoproteins; and 4.8 +/- 0.5% in lymph chylomicrons. Concentration in whole serum was 18.1 +/- 1.4 and 20.4 +/- 2.3 mg/dl for male and female rats, respectively. Only about 55% of arginine-rich protein was recovered in the major lipoprotein classes and about 40% was in "lipoprotein-free" serum (d greater than 1.25 g/ml). Among the lipoproteins, the high density lipoprotein fraction contained twice the amount of arginine-rich protein recovered in very low or low density lipoproteins (26.6 vs. 13.5 and 13.4%, respectively). The significance of the large amount of arginine-rich protein in the 1.25 g/ml infranatant fraction is not apparent. Although repetitive centrifugation did not alter the amount recovered in this fraction, the possibility of an artifact induced by centrifugation and high salt concentration cannot be excluded.

Amino Acids↗
PubMed1977

Evidence that a separate particle containing B-apoprotein is present in high-density lipoproteins from perfused rat liver.

High-density lipoproteins (HDL) (1.075 less than d less than 1.175) from perfusates of rat liver, unlike those of blood plasma, contain protein with the properties of B-apolipoprotein. This protein remains near the origin upon electrophoresis in polyacrylamide gels containing sodium dodecyl sulfate, has beta electrophoretic mobility in agarose gel, is insoluble in tetramethylurea, and precipitates with antisera to the B-apoprotein isolated from low-density lipoprotein. B-apolipoprotein in HDL from perfusates binds to concanavalin-A Sepharose and can thus be separated from the characteristic HDL, the chemical and physical properties of which are otherwise preserved. These observations suggest that in addition to the discoidal lipoproteins, another particle that contains B-apoprotein exists in HDL of perfusates.

Animals↗