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Abstract
Although Becker's naevus is most common in males, cases with associated lipoatrophy are more frequently reported in women. Two women are described in whom Becker's naevus of the thigh was associated with localized lipoatrophy. Neither had any bony abnormality or functional deficit.
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202
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Volkert R. [Therapy of lipodystrophy: no clear answers to clinical questions]. Dtsch Med Wochenschr 2001; 126:A1118. [PMID: 11791516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
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203
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Machinami R. [Membranous lipodystrophy of the bone]. Ann Pathol 2001; 21:524-8. [PMID: 11910939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
Membranous lipodystrophy is a rare disease in which cyst-like lesions of fat occur in subcutaneous and other sites including bone marrow, together with sudanophilic leukoencephalopathy. The disease has been reported mostly in Finland and in Japan, with sporadic cases from USA, Belgium, Italy, and France. The cyst-like lesions of limb bones progress in early adult life, usually followed by neurological disorders including convulsions and presenile dementia. Histologically, the fat cells of the bone marrow, synovial membrane, and other sites, are replaced by a convoluted, hyaline, eosinophilic membrane that surrounds a large space. The histochemical and ultrastructural characteristics of the membranes are described. In the brain, atrophy of the subcortical white matter of the frontal and temporal lobes with marked astrocytosis and fibrillary gliosis, and a slight or moderate degeneration of myelin sheaths, are the most prominent changes. Genetic studies of the disease have been reported, revealing an autosomal recessive gene, explaining both its sporadic and familial occurrence, with mutations involving the gene encoding a transmembrane protein, key activating signal transduction element in NK cells (TYROBP). The pathogenesis of membranocystic changes is still unknown: result of a metabolic disorder or circulatory disturbances.
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204
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Masala MV, Tedde G, Cottoni F. Annular atrophy of the ankles: an unusual case associated with bone anomaly. Dermatology 2001; 203:81-2. [PMID: 11549808 DOI: 10.1159/000051711] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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205
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Graber AL. Syndrome of lipodystrophy, hyperlipidemia, insulin resistance, and diabetes in treated patients with human immunodeficiency virus infection. Endocr Pract 2001; 7:430-7. [PMID: 11747278 DOI: 10.4158/ep.7.6.430] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
OBJECTIVE To describe the syndrome of lipodystrophy, hyperlipidemia, insulin resistance, and diabetes in patients with human immunodeficiency virus (HIV) infection treated with protease inhibitor drugs. METHODS This is a case series of patients referred from an infectious disease clinic to a diabetes-endocrinology clinic in an academic medical center because of severe metabolic problems that occurred during the course of otherwise-successful treatment of HIV infection. The clinical course, abnormalities on physical examination, laboratory data, and complications are described and analyzed. The pathogenesis of the syndrome is discussed and compared with that of type 2 diabetes, lipoatrophic diabetes, and mouse models of lipodystrophy. RESULTS In six male patients receiving antiretroviral therapy for HIV infection, a syndrome of lipoatrophy of the face, legs, and buttocks, hyperlipidemia (predominantly hypertriglyceridemia), and type 2 diabetes mellitus was noted. Two patients had pronounced abdominal obesity, in contrast to their thin extremities. Five of the six patients were receiving protease inhibitor drugs, which have been thought to contribute to metabolic abnormalities. In two patients, ischemic heart disease had developed. CONCLUSION Protease inhibitors frequently cause insulin resistance and lipoatrophy in subcutaneous adipose tissue. These abnormalities are associated with visceral adiposity, hyperlipidemia, diabetes, and cardiovascular consequences and represent an important and unsolved problem in the treatment of HIV-infected patients.
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206
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James JS. Treatment news from recent conferences: finding Web reports. AIDS TREATMENT NEWS 2001:3-7. [PMID: 11768881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
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207
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Sattler FR, Qian D, Louie S, Johnson D, Briggs W, DeQuattro V, Dube MP. Elevated blood pressure in subjects with lipodystrophy. AIDS 2001; 15:2001-10. [PMID: 11600829 DOI: 10.1097/00002030-200110190-00013] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
OBJECTIVES To assess the prevalence of elevated blood pressure in patients with lipodystrophy. DESIGN Case-control study. PARTICIPANTS Forty-two patients with abnormal body fat (100%) and serum lipids (86%) (HIV-positive cohort) were matched by age and sex to 42 HIV-positive controls without previously diagnosed lipodystrophy and to 13 HIV-negative controls. SETTING Tertiary care, university-based, fully dedicated HIV clinic. MAIN OUTCOME MEASURES Frequency and magnitude of elevated blood pressure during highly active antiretroviral therapy. RESULTS There were 23 +/- 16 and 22 +/- 12 blood pressure measurements recorded per subject over 21 +/- 11 and 22 +/- 11 months for the HIV-positive cohort and HIV-positive controls, respectively. Three or more elevated readings occurred in 74% of the cohort and in 48% of the HIV-positive controls (P = 0.01) and accounted for 38 +/- 25% versus 22 +/- 26% (P = 0.01) of the total readings, respectively. The average of the three highest systolic readings (153 +/- 17 versus 144 +/- 15 mmHg; P = 0.01) and diastolic readings (92 +/- 10 versus 87 +/- 9 mmHg; P = 0.01) was greater for the cohort than for the HIV-positive controls. Family history of hypertension was more common in the cohort than in the controls but accounted for only 13% of the log odds ratio value for elevated blood pressure in the cohort. Systolic blood pressure was correlated with waist-to-hip ratios in the cohort (r = 0.45; P = 0.003) but not in the HIV controls (r = 0.06; P = 0.68) and tended to be related to fasting triglycerides (r = 0.34; P = 0.052) in subjects with HIV. CONCLUSIONS Elevated blood pressure may be linked to the metabolic disorders occurring in patients with HIV, as in the dysmetabolic syndrome.
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208
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Mascolini M. HIV news from Buenos Aires: Part 2--symmetries and semistops. IAPAC MONTHLY 2001; 7:294-308. [PMID: 11785462] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
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209
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Dalton B. PWA with lipodystrophy takes on an HMO (and wins!). POSITIVE LIVING (LOS ANGELES, CALIF.) 2001; 10:34-5. [PMID: 11702754] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
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210
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Lee IH, Chen HL, Jeng YM, Cheng MT, Tsao LY, Chang MH. Congenital generalized lipodystrophy in a 4-month-old infant. J Formos Med Assoc 2001; 100:623-7. [PMID: 11695279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2023] Open
Abstract
Congenital generalized lipodystrophy (CGL, Berardinelli-Seip syndrome) is a rare autosomal recessive disorder with a clinical presentation of paucity of adipose tissue, muscular hypertrophy, organomegaly, and insulin-resistant diabetes. A 4-month-old Taiwanese female infant had hepatosplenomegaly and low body weight gain despite a voracious appetite. Hypermetabolism, hyperhidrosis, loss of subcutaneous fat, muscular hypertrophy, acanthosis nigricans, hypertrichosis, and marked hypertriglyceridemia were also noted. Liver histology revealed fatty change and portal-to-portal bridging fibrosis. Clinical features, serum biochemistry, and liver histology were compatible with the diagnosis of CGL. She was given a special diet characterized by calorie restriction and partial substitution of long-chain triglycerides with medium-chain triglycerides. The serum triglyceride concentration subsequently decreased. This present case suggests that extensive fatty infiltration and subsequent cirrhosis of the liver may be the earliest complication of CGL.
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211
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Bülbül M, Demircin G, Altuntaş B, Memiş L, Oner A. Acute pancreatitis in a patient with partial lipodystrophy and membranoproliferative glomerulonephritis. Nephrol Dial Transplant 2001; 16:1930-1. [PMID: 11522882 DOI: 10.1093/ndt/16.9.1930] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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212
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Berger DS. New facial filling treatment for lipodystrophy. POSITIVELY AWARE : THE MONTHLY JOURNAL OF THE TEST POSITIVE AWARE NETWORK 2001; 12:17-20. [PMID: 11688478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
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213
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Rose AR, Subhash HS, Danda D, Cherian AM. Lipodystrophy and connective tissue panniculitis. Rheumatology (Oxford) 2001; 40:1070-1. [PMID: 11561125 DOI: 10.1093/rheumatology/40.9.1070] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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214
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[Stigma, psychological stress and cardiovascular risk: long-term complications of lipodystrophy]. MMW Fortschr Med 2001; 143:53. [PMID: 11561461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
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215
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Magré J, Delépine M, Khallouf E, Gedde-Dahl T, Van Maldergem L, Sobel E, Papp J, Meier M, Mégarbané A, Bachy A, Verloes A, d'Abronzo FH, Seemanova E, Assan R, Baudic N, Bourut C, Czernichow P, Huet F, Grigorescu F, de Kerdanet M, Lacombe D, Labrune P, Lanza M, Loret H, Matsuda F, Navarro J, Nivelon-Chevalier A, Polak M, Robert JJ, Tric P, Tubiana-Rufi N, Vigouroux C, Weissenbach J, Savasta S, Maassen JA, Trygstad O, Bogalho P, Freitas P, Medina JL, Bonnicci F, Joffe BI, Loyson G, Panz VR, Raal FJ, O'Rahilly S, Stephenson T, Kahn CR, Lathrop M, Capeau J. Identification of the gene altered in Berardinelli-Seip congenital lipodystrophy on chromosome 11q13. Nat Genet 2001; 28:365-70. [PMID: 11479539 DOI: 10.1038/ng585] [Citation(s) in RCA: 500] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Congenital generalized lipodystrophy, or Berardinelli-Seip syndrome (BSCL), is a rare autosomal recessive disease characterized by a near-absence of adipose tissue from birth or early infancy and severe insulin resistance. Other clinical and biological features include acanthosis nigricans, hyperandrogenism, muscular hypertrophy, hepatomegaly, altered glucose tolerance or diabetes mellitus, and hypertriglyceridemia. A locus (BSCL1) has been mapped to 9q34 with evidence of heterogeneity. Here, we report a genome screen of nine BSCL families from two geographical clusters (in Lebanon and Norway). We identified a new disease locus, designated BSCL2, within the 2.5-Mb interval flanked by markers D11S4076 and D11S480 on chromosome 11q13. Analysis of 20 additional families of various ethnic origins led to the identification of 11 families in which the disease cosegregates with the 11q13 locus; the remaining families provide confirmation of linkage to 9q34. Sequence analysis of genes located in the 11q13 interval disclosed mutations in a gene homologous to the murine guanine nucleotide-binding protein (G protein), gamma3-linked gene (Gng3lg) in all BSCL2-linked families. BSCL2 is most highly expressed in brain and testis and encodes a protein (which we have called seipin) of unknown function. Most of the variants are null mutations and probably result in a severe disruption of the protein. These findings are of general importance for understanding the molecular mechanisms underlying regulation of body fat distribution and insulin resistance.
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216
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Abstract
Highly active antiretroviral therapies (HAART) lower morbidity and mortality of HIV infection, but are unable to eradicate HIV and may cause side-effects. Planned interruptions of HAART are studied for three reasons: (1) to stimulate the anti-HIV immune response after viraemia has been suppressed by treatment; (2) to increase time off drug, to improve quality of life and diminish side effects and costs; and (3), among individuals whose virus has become resistant to treatment, to induce reversion of resistance to wild-type and therefore to improve the chances of success of subsequent salvage therapy. Regarding immune stimulation, the most promising results come from rare patients who started HAART during primary HIV infection. Up to 60% controlled viraemia below 5,000 copies/mL for up to 1 year without HAART. Among the majority of patients who start HAART later, during chronic HIV infection, preliminary results suggest that after repeated cycles on and off therapy, about 20% remain with a viraemia below 5,000 copies/mL after 12 weeks' treatment interruption. For the 80% who rebound to higher viraemia, additional immune-stimulatory manoeuvres are being considered such as administration of cytokines, or specific immune treatment by anti-HIV vaccines. When treatment is interrupted in patients who fail HAART and who have drug-resistant HIV, the drug-sensitive wild-type replaces the resistant quasispecies in 30-60% of patients. It remains to be seen whether this phenomenon increases the chances of successful salvage therapy. The risks and benefits of treatment interruption still have to be compared in large clinical trials, which are currently in the planning stage.
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217
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Borderi M, Verucchi G, Tadolini M, Spinosa S, Fortunato L, Talò S, Chiodo F. Metabolic complications of HIV-1 antiretroviral therapy: the lipodystrophy syndrome. THE NEW MICROBIOLOGICA 2001; 24:303-15. [PMID: 11497090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Abstract
The lipodystrophy syndrome is one of the complications reported with increased frequency in patients with HIV-1 infection receiving antiretroviral therapy. The wide range of prevalence estimates may be due to differing definitions, methods and patient populations. We described the various pathogenic theories and the morphological and metabolic alterations associated with this syndrome. Even if no effective treatment exists, a correct lifestyle, adequate diet and physical exercise seem to be very important. Moreover drug therapies should be used with care to avoid potentially harmful interactions with antiretroviral agents. Ideally, the future effort to define the mechanism of lipodystrophy would be multidisciplinary and would involve not only experts in AIDS research but also nutritionists, endocrinologists and cardiologists.
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218
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Ruiz L, Negredo E, Domingo P, Paredes R, Francia E, Balagué M, Gel S, Bonjoch A, Fumaz CR, Johnston S, Romeu J, Lange J, Clotet B. Antiretroviral treatment simplification with nevirapine in protease inhibitor-experienced patients with hiv-associated lipodystrophy: 1-year prospective follow-up of a multicenter, randomized, controlled study. J Acquir Immune Defic Syndr 2001; 27:229-36. [PMID: 11464141 DOI: 10.1097/00126334-200107010-00003] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Simpler and less toxic antiretroviral strategies are needed to maximize treatment compliance without sacrificing potency, at least for drug-experienced HIV-infected patients currently on regimens containing protease inhibitors (PIs). Small nonrandomized studies have suggested a beneficial role of PI-sparing regimens on lipodystrophy. OBJECTIVES To assess the virologic, immunologic, and clinical benefit of switching the PI to nevirapine in patients with HIV-associated lipodystrophy and sustained viral suppression before entry in the study. DESIGN Open-labeled, prospective, randomized, multicenter study. SETTING Seven reference inpatient centers for HIV/AIDS in Spain. PATIENTS One hundred six HIV-infected adults with clinically evident lipodystrophy who sustained HIV-RNA suppression for at least 6 months with PI-containing antiretroviral combinations. INTERVENTION Replacement of the PI with nevirapine during 48 weeks (Group A) versus continuing the prior PI (Group B). MEASUREMENTS Several virologic and immunologic analyses, standard and specific biochemical tests, and anthropometric and dual X-ray absorptiometry measurements. RESULTS At week 48, an HIV-1 RNA level <400 copies/ml was maintained in 79% and 77% of patients in Groups A and B, respectively, whereas 74% and 72% of patients had viral load levels <50 copies/ml. Absolute CD4+ counts significantly increased in both groups compared with baseline values, and a significant decrease in CD38+CD8+ cells was observed in Group A (p <.01) but not in group B. Overall, no significant changes in anthropometric or body shape measurements were found after 48 weeks. Fasting total cholesterol and triglyceride levels decreased in Group A (but not in Group B) compared with baseline values (p <.05), although no significant differences were seen between groups at the end of the study. Subjects in Group A reported a better quality of life (QOL) index than controls (p <.001), with the main reason reported being the greater simplicity of the new drug regimen. CONCLUSIONS Protease inhibitor-sparing regimens, including nevirapine, seem to be an effective alternative for PI-experienced patients. Nevirapine-based triple therapies allow maintained control of HIV-1 RNA levels and improve the immunologic response at 48 weeks of follow-up in patients with prior sustained virologic suppression. The switch to nevirapine significantly improved the lipidic profile in Group A, although there were no differences between groups at the end of the study. Additionally, no significant changes were seen in terms of lipodystrophy-related body shape changes 1 year after the PI substitution. Finally, nevirapine-containing regimens have a simpler dosing schedule, and this facilitates high adherence and improves QOL.
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219
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Wedekind CA, Pugatch D. Lipodystrophy syndrome in children infected with human immunodeficiency virus. Pharmacotherapy 2001; 21:861-6. [PMID: 11444583 DOI: 10.1592/phco.21.9.861.34555] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Lipodystrophy syndrome (LDS), a fat-wasting condition commonly reported in adults infected with human immunodeficiency virus (HIV), has been linked to the use of antiretroviral agents. Recently, LDS was observed in children infected with HIV Little is known about the pathophysiology of this condition, although it is believed that LDS has many causes and modes of presentation. Even less is known about what long-term effects LDS will have on HIV-infected patients. Three patients who developed LDS were observed in a pediatric HIV clinic. Due to the lack of knowledge about the condition's natural course and the benefits versus risks of treatment, they were not treated specifically for LDS. Their lipid profiles, however, continue to be monitored closely twice/year.
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220
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Duong M, Petit JM, Piroth L, Grappin M, Buisson M, Chavanet P, Hillon P, Portier H. Association between insulin resistance and hepatitis C virus chronic infection in HIV-hepatitis C virus-coinfected patients undergoing antiretroviral therapy. J Acquir Immune Defic Syndr 2001; 27:245-50. [PMID: 11464143 DOI: 10.1097/00126334-200107010-00005] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Insulin resistance (IR) in the context of highly active antiretroviral therapy (HAART) is becoming more common in HIV-infected patients. Patients with chronic hepatitis C virus (HCV) infection have an increased risk of IR and type 2 diabetes mellitus. A cross-sectional study was performed to investigate whether chronic HCV infection constitutes a risk factor for IR in HIV-HCV-coinfected patients undergoing HAART. Inclusion criteria were positive HCV viremia and a sustained increase of alanine aminotransferase of at least twice the normal value. A total of 29 HIV-HCV patients, 76 HIV patients, and 121 HCV controls were tested for IR and body mass index (BMI). IR was measured using the homeostasis model assessment. In HIV-HCV and HIV patients, fat redistribution and lipid profile were assessed. There was no significant difference in age, CD4 cell count, HIV viral load, or duration of HAART between the HIV-HCV and HIV groups. HIV-HCV patients and HCV controls had a significant increase in IR when compared with HIV patients (0.25 +/- 0.28 and 0.21 +/- 0.34 versus 0.04 +/- 0.37; p =.01 and p =.003, respectively). Lipoatrophy was observed more frequently in HIV-HCV patients in comparison with HIV patients (41% versus 14%; p =.003). In HIV-HCV patients, total cholesterol and triglyceride levels were significantly lower than in HIV patients. In multivariate analysis, IR, BMI, triglyceride levels, and peripheral fat wasting were the independent variables associated with HCV infection. Our findings suggest that chronic HCV infection is a significant factor associated with the development of metabolic abnormalities and with modifications in body composition in HIV patients receiving antiretroviral treatment.
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221
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Gilbert C. [Education of the diabetic patient--insulin injection and lipodystrophy]. SOINS; LA REVUE DE REFERENCE INFIRMIERE 2001:23-5. [PMID: 11301548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
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223
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Devaux JP, Andrieux S, Melliez H, Copin MC, Azar R. [Type 1 membranoproliferative glomerulonephritis in a patient with acquired partial lipodystrophy]. Presse Med 2001; 30:790-1. [PMID: 11388149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/20/2023] Open
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224
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Wilder TL. Delaney updates Atlanta on retrovirus conference. SURVIVAL NEWS (ATLANTA, GA.) 2001:9-11. [PMID: 11683027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
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225
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Zhang J, Ou J, Bashmakov Y, Horton JD, Brown MS, Goldstein JL. Insulin inhibits transcription of IRS-2 gene in rat liver through an insulin response element (IRE) that resembles IREs of other insulin-repressed genes. Proc Natl Acad Sci U S A 2001; 98:3756-61. [PMID: 11259670 PMCID: PMC31125 DOI: 10.1073/pnas.071054598] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Recent data indicate that sustained elevations in plasma insulin suppress the mRNA for IRS-2, a component of the insulin signaling pathway in liver, and that this deficiency contributes to hepatic insulin resistance and inappropriate gluconeogenesis. Here, we use nuclear run-on assays to show that insulin inhibits transcription of the IRS-2 gene in the livers of intact rats. Insulin also inhibited transcription of a reporter gene driven by the human IRS-2 promoter that was transfected into freshly isolated rat hepatocytes. The human promoter contains a heptanucleotide sequence, TGTTTTG, that is identical to the insulin response element (IRE) identified previously in the promoters of insulin-repressed genes. Single base pair substitutions in this IRE decreased transcription of the IRS-2-driven reporter in the absence of insulin and abolished insulin-mediated repression. We conclude that insulin represses transcription of the IRS-2 gene by blocking the action of a positive factor that binds to the IRE. Sustained repression of IRS-2, as occurs in chronic hyperinsulinemia, contributes to hepatic insulin resistance and accelerates the development of the diabetic state.
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