RESUMO

We tested whether low high-density lipoprotein cholesterol (HDL-C) and/or high triglycerides are associated to abnormal HDL subclasses distribution and composition, and their relationships with fasting insulin and C-reactive protein (CRP). Four groups of adolescents were studied: group 1 (HDL-C< or =35 mg/dl+TG> or =150 mg/dl; n=16); group 2 (isolated HDL-C< or =35 mg/dl; n=31); group 3 (isolated TG> or =150 mg/dl; n=20); and group 4 (CT<200 mg/dl, HDL-C>35 mg/dl, LDL-C<130 mg/dl, and TG<150 mg/dl; n=39). Tanner score-adjusted proportions of large subspecies (HDL(2b), HDL(2a)) were lower, and small (HDL(3b), HDL(3c)) were higher in groups 1, 2 and 3 than in group 4. As a result, HDL particle size in the three dyslipidemic groups was smaller than in group 4 (p<0.001). HDL CE, FC, PL, and apo AI percent contents were lower, whereas HDL TG percent content was higher in groups 1, 2 and 3 compared to group 4. CRP median values were also significantly higher in the three groups with dyslipidemia than in normolipidemic subjects (group 4). Fasting Insulin concentration and HOMA-IR were significantly higher in group 1 than in the other three groups. In stepwise multivariate analysis HDL subclass distribution and composition were independently associated only with HDL-C and waist circumference. As reported in adults, adolescents with low HDL-C and/or high TG have abnormalities in HDL subclasses distribution and lipid composition, which may render their HDL dysfunctional. In addition, these subjects have high CRP and insulin levels suggesting the presence of chronic low-grade inflammation.

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RESUMO

Biosynthetic processes related to the production of an insect hexamerin, very high density lipoprotein (VHDL), have been examined in the fat body of fifth-instar nymph and adult Triatoma infestans. Fat bodies were incubated in vitro with [3H]leucine and the incubation media were precipitated using a specific antiserum. The SDS-polyacrylamide gel electrophoresis followed by blotting on nitrocellulose showed that both larval and adult fat body secreted the VHDL subunit. Moreover, the radiolabel recovered in this subunit is indicative of the de novo synthesis. When the incubation medium was subjected to density gradient ultracentrifugation, a radiolabeled fraction was found at density 1.27 g/ml, value identical to the hemolymph circulating VHDL, indicating that the secreted apoprotein is combined with lipids. The SDS-polyacrylamide gel electrophoresis and immunoblotting of this fraction corroborated the presence of the VHDL-apoprotein. These results demonstrate that the fat body of T. infestans is able to synthesize the protein subunit which is associated to lipids as a lipoprotein particle that is released into the medium as VHDL.

Assuntos

RESUMO

Biosynthetic processes related to the production of an insect hexamerin, very high density lipoprotein (VHDL), have been examined in the fat body of fifth-instar nymph and adult Triatoma infestans. Fat bodies were incubated in vitro with [3H] leucine and the incubation media were precipitated using a specific antiserum. The SDS-polyacrylamide gel electrophoresis followed by blotting on nitrocellulose showed that both larval and adult fat body secreted the VHDL subunit. Moreover, the radiolabel recovered in this subunit is indicative of the de novo synthesis. When the incubation medium was subjected to density gradient ultracentrifugation, a radiolabeled fraction was found at density 1.27 g/ml, value identical to the hemolymph circulating VHDL, indicating that the secreted apoprotein is combined with lipids. The SDS-polyacrylamide gel electrophoresis and immunoblotting of this fraction corroborated the presence of the VHDL-apoprotein. These results demonstrate that the fat body of T. infestans is able to synthesize the protein subunit which is associated to lipids as a lipoprotein particle that is released into the medium as VHDL.

Assuntos

RESUMO

Biosynthetic processes related to the production of an insect hexamerin, very high density lipoprotein (VHDL), have been examined in the fat body of fifth-instar nymph and adult Triatoma infestans. Fat bodies were incubated in vitro with [3H] leucine and the incubation media were precipitated using a specific antiserum. The SDS-polyacrylamide gel electrophoresis followed by blotting on nitrocellulose showed that both larval and adult fat body secreted the VHDL subunit. Moreover, the radiolabel recovered in this subunit is indicative of the de novo synthesis. When the incubation medium was subjected to density gradient ultracentrifugation, a radiolabeled fraction was found at density 1.27 g/ml, value identical to the hemolymph circulating VHDL, indicating that the secreted apoprotein is combined with lipids. The SDS-polyacrylamide gel electrophoresis and immunoblotting of this fraction corroborated the presence of the VHDL-apoprotein. These results demonstrate that the fat body of T. infestans is able to synthesize the protein subunit which is associated to lipids as a lipoprotein particle that is released into the medium as VHDL. (AU)

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RESUMO

En este trabajo se determinaron los valores promedio, desviación estándar y percentilos para el cociente Apo B/C-HDL y, por otra parte, se analizó el efecto de las lipoproteínas ricas en triglicéridos sobre la relación entre C-LDL y Apo B, determinada por electroinmunodifusión en suero total. Se estudiaron 74 individuos de 20 y más años, aparentemente sanos. Para Apo B/C-HDL se obtuvo un valor medio de 2,16+0,78. El percentilo 50 fue 2,00, el percentilo 75 fue 2,60 y el percentilo 95 fue 3,60. Los individuos con Apo B/C-HDL>3,60 estarían en riesgo respecto de la aterosclerosis coronaria. La relación entre C-LDL y Apo B, es importante para la detección de sujetos con hiperapo B, la cual está fuertemente relacionada con la aterosclerosis coronaria. Utilizando los triglicéridos como estimadores de masa de las lipoproteínas ricas en triglicéridos, se halló que mientras TG<160 mg/dl la correlación entre Apo B y C-LDL fue r= +0,65,P <0,001. Un 86% de los pacientes con C-LDL entre 80 y 165 mg/dl tenían Apo B entre 55 y 120 mg/dl, mientras que un 12% tenían Apo B por encima de 120 mg/dl. En estos pacientes se puede suponer la presencia de hiperapo B en estas condiciones experimentales. Cuando TG>160 mg/dl, la correlación entre Apo B y C-LDL disminuye a r=+0,39,P<0,1. Un 21% de los pacientes con C-LDL entre 80 y 165 mg/dl tenían Apo B entre 55 y 120 mg/dl, pero un 79% tenían Apo B por encima de 120 mg/dl. En estas condiciones experimentales no se podrían discriminar los pacientes con hiperapo B.

Assuntos

RESUMO

En este trabajo se determinaron los valores promedio, desviación estándar y percentilos para el cociente Apo B/C-HDL y, por otra parte, se analizó el efecto de las lipoproteínas ricas en triglicéridos sobre la relación entre C-LDL y Apo B, determinada por electroinmunodifusión en suero total. Se estudiaron 74 individuos de 20 y más años, aparentemente sanos. Para Apo B/C-HDL se obtuvo un valor medio de 2,16+0,78. El percentilo 50 fue 2,00, el percentilo 75 fue 2,60 y el percentilo 95 fue 3,60. Los individuos con Apo B/C-HDL>3,60 estarían en riesgo respecto de la aterosclerosis coronaria. La relación entre C-LDL y Apo B, es importante para la detección de sujetos con hiperapo B, la cual está fuertemente relacionada con la aterosclerosis coronaria. Utilizando los triglicéridos como estimadores de masa de las lipoproteínas ricas en triglicéridos, se halló que mientras TG<160 mg/dl la correlación entre Apo B y C-LDL fue r= +0,65,P <0,001. Un 86% de los pacientes con C-LDL entre 80 y 165 mg/dl tenían Apo B entre 55 y 120 mg/dl, mientras que un 12% tenían Apo B por encima de 120 mg/dl. En estos pacientes se puede suponer la presencia de hiperapo B en estas condiciones experimentales. Cuando TG>160 mg/dl, la correlación entre Apo B y C-LDL disminuye a r=+0,39,P<0,1. Un 21% de los pacientes con C-LDL entre 80 y 165 mg/dl tenían Apo B entre 55 y 120 mg/dl, pero un 79% tenían Apo B por encima de 120 mg/dl. En estas condiciones experimentales no se podrían discriminar los pacientes con hiperapo B. (AU)

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RESUMO

The three lipoproteins of high (HDL) and very high density (VHDL-I and VHDL-II) were separated from the hemolymph of adult males of T. infestans. They were delipidated and the corresponding apolipoproteins examined by sodium dodecyl sulphate (SDS) gel electrophoresis in polyacrylamide in the presence of 2-mercaptoethanol. They were also iso-electro focused in a pH gradient of 5 to 8. All three groups of apolipoproteins were separated in several polypeptide chains, but all of them had in common a glycoproteic unit of PM 86 000. The VHDL-II presented the simplest composition with predominance of the 86 000 band. Apo-HDL was the most complicated and showed intense bands of PM as high as 210 000 and as low as 17 000 together with 44 000 and 86 000 and less intense bands. The apo-VHDL-I was separated in polypeptides chains in the range of 86 000 to 17 000. The different apoproteins are apparently formed by the association at least in part of common polypeptides.

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