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1.
Osteoporos Int ; 23(6): 1747-56, 2012 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-21953471

RESUMEN

UNLABELLED: The long-term efficacy and safety of once-monthly ibandronate were studied in this extension to the 2-year Monthly Oral Ibandronate in Ladies (MOBILE) trial. Over 5 years, lumbar spine bone mineral density (BMD) increased from baseline with monthly ibandronate 150 mg (8.4%). Long-term monthly ibandronate is effective and well tolerated for up to 5 years in women with postmenopausal osteoporosis. INTRODUCTION: Once-monthly therapy with ibandronate has been studied for up to 5 years in a long-term extension (LTE) to the 2 year MOBILE trial. METHODS: This multicenter, double-blind extension study of monthly ibandronate involved postmenopausal women who had completed 2 years of the MOBILE core study, with ≥75% adherence. Patients were reallocated, or were randomized from daily therapy, to ibandronate 100 mg monthly or 150 mg monthly for a further 3 years. RESULTS: A pooled intent-to-treat (ITT) analysis of 344 patients receiving monthly ibandronate from the core MOBILE baseline showed increases over 5 years in lumbar spine BMD (8.2% with 100 mg and 8.4% with 150 mg). Three-year data relative to MOBILE LTE baseline in the full ITT population of all 698 patients randomized or reallocated from MOBILE (including those previously on daily treatment) showed, on average, maintenance of proximal femur BMD gains achieved in the core 2-year study, with further small gains in lumbar spine BMD. In general, maintenance of efficacy was also indicated by markers of bone metabolism. CONCLUSIONS: There were no tolerability concerns or new safety signals. Monthly treatment with ibandronate 100 and 150 mg is effective and well tolerated for up to 5 years in women with postmenopausal osteoporosis.


Asunto(s)
Conservadores de la Densidad Ósea/uso terapéutico , Difosfonatos/uso terapéutico , Osteoporosis Posmenopáusica/tratamiento farmacológico , Absorciometría de Fotón , Anciano , Anciano de 80 o más Años , Biomarcadores/metabolismo , Densidad Ósea/fisiología , Conservadores de la Densidad Ósea/administración & dosificación , Remodelación Ósea , Difosfonatos/administración & dosificación , Método Doble Ciego , Femenino , Fémur/diagnóstico por imagen , Humanos , Ácido Ibandrónico , Vértebras Lumbares/diagnóstico por imagen , Persona de Mediana Edad , Resultado del Tratamiento
2.
Bone ; 34(5): 890-9, 2004 May.
Artículo en Inglés | MEDLINE | ID: mdl-15121021

RESUMEN

Less frequent bisphosphonate dosing in women with postmenopausal osteoporosis has the potential to promote therapy adherence through improved convenience. Ibandronate is a highly potent nitrogen-containing bisphosphonate, proven to significantly increase vertebral and nonvertebral bone mineral density (BMD) when administered as a convenient intravenous injection. A recent double-blind, placebo-controlled, randomized phase III study explored the antifracture efficacy and safety of 1 and 0.5 mg iv ibandronate injections, given once every 3 months, in 2862 women (55-76 years) with postmenopausal osteoporosis [one to four prevalent vertebral fractures and lumbar spine (L1-L4) BMD T score of less than -2.0 and greater than -5.0 in >or=1 vertebra]. All participants received daily vitamin D (400 IU) and calcium (500 mg) supplementation. The primary endpoint was the incidence of new morphometric vertebral fractures after 3 years. However, although a consistent trend toward a reduction in the incidence of new morphometric vertebral fracture was observed in the active treatment arms compared with placebo (9.2% vs. 8.7% vs. 10.7% in the 1 mg, 0.5 mg and placebo groups, respectively), as well as in the incidence of nonvertebral and hip fractures, the magnitude of fracture reduction was suboptimal and was insufficient to achieve statistical significance. At the studied doses, intravenous ibandronate injections also produced dose-dependent, but comparatively small, increases in lumbar spine BMD (4.0% and 2.9%, respectively) and decreases in biochemical markers of bone resorption and formation, relative to placebo. Optimal fracture efficacy likely requires more substantial increases in BMD and more pronounced suppression of bone turnover. In light of the clear dose-response relationship observed in this and other studies, this is likely to be achieved with higher intravenous doses of ibandronate. The results of a recent phase II/III study (Intermittent Regimen Intravenous Ibandronate Study: the IRIS study) provide support for this hypothesis.


Asunto(s)
Difosfonatos/uso terapéutico , Fracturas Óseas/prevención & control , Osteoporosis/tratamiento farmacológico , Posmenopausia , Anciano , Resorción Ósea/tratamiento farmacológico , Difosfonatos/administración & dosificación , Método Doble Ciego , Femenino , Humanos , Ácido Ibandrónico , Infusiones Intravenosas , Persona de Mediana Edad , Placebos
3.
Osteoporos Int ; 15(10): 792-8, 2004 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-15071723

RESUMEN

Increasing evidence suggests that a high rate of bone turnover is associated with low bone mineral density (BMD) and is strongly linked to fracture risk. Measurement of biochemical markers of bone turnover is therefore becoming a more widely used endpoint in clinical trials in postmenopausal osteoporosis. This multinational double-blind, fracture-prevention study enrolled 2946 postmenopausal women with osteoporosis. Patients were randomized to receive placebo or oral ibandronate administered daily (2.5 mg/day) or intermittently (20 mg every other day for 12 doses every 3 months). The primary endpoint was the incidence of new vertebral fractures after 3 years. Secondary outcome measures included changes in the rate of bone turnover as assessed by biochemical markers and increases in spinal and hip BMD. Daily and intermittent oral ibandronate significantly reduced the risk of vertebral fractures by 62% and 50%, respectively, and produced significant and sustained reductions in all the measured biochemical markers of bone turnover. By 3 months, the rate of bone turnover was reduced by approximately 50-60%, and this level of suppression was sustained throughout the remainder of the study. In summary, oral ibandronate, given daily or with a between-dose interval of >2 months, normalizes the rate of bone turnover, provides significant increases in BMD and a marked reduction in the incidence of vertebral fractures. Thus, intermittent ibandronate has potential to become an important alternative to currently licensed bisphosphonates in postmenopausal osteoporosis.


Asunto(s)
Resorción Ósea/tratamiento farmacológico , Difosfonatos/administración & dosificación , Fracturas de la Columna Vertebral/prevención & control , Administración Oral , Anciano , Anciano de 80 o más Años , Biomarcadores/sangre , Densidad Ósea/fisiología , Resorción Ósea/complicaciones , Colágeno/orina , Colágeno Tipo I , Creatinina/orina , Difosfonatos/efectos adversos , Método Doble Ciego , Esquema de Medicación , Femenino , Cadera , Humanos , Ácido Ibandrónico , Vértebras Lumbares/fisiopatología , Persona de Mediana Edad , Osteocalcina/sangre , Péptidos/orina , Factores de Riesgo , Fracturas de la Columna Vertebral/etiología , Fracturas de la Columna Vertebral/fisiopatología , Resultado del Tratamiento
4.
Ann Rheum Dis ; 62(10): 969-75, 2003 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-12972476

RESUMEN

OBJECTIVE: To investigate the efficacy, safety, and dose response of three doses of ibandronate, given intermittently by intravenous (IV) injection every three months, in preventing postmenopausal osteoporosis. PATIENTS AND METHODS: 629 postmenopausal women, categorised according to time since menopause and baseline lumbar spine (L1-4) bone mineral density (BMD), were enrolled into a multicentre, double blind, placebo controlled trial. They were randomly allocated to receive IV ibandronate 0.5 mg, 1 mg or 2 mg, or placebo every three months. All women received daily calcium supplementation. RESULTS: One year's treatment with intermittent IV ibandronate injections produced a dose dependent gain in mean (SD) lumbar spine BMD from baseline of 2.5 (2.5)%, 1.8 (2.6)%, and 1.0 (2.8)% in the groups receiving 2 mg, 1 mg, and 0.5 mg ibandronate, respectively, compared with a loss of BMD of 0.4 (2.4)% in the women in the placebo group; p=0.0001 for each ibandronate dose v placebo. Highest BMD gains occurred in women with osteopenia receiving 2 mg ibandronate. Similarly, at the hip, all three doses of ibandronate produced significantly better gains in BMD than placebo (p<0.05), with the greatest gains in the women with osteopenia receiving the 2 mg dose. Ibandronate concomitantly and dose dependently suppressed markers of bone turnover in comparison with placebo, and injections were well tolerated. CONCLUSION: IV ibandronate injections, given every three months, may be an effective alternative to oral bisphosphonates and hormonal therapy in the prevention of bone loss in postmenopausal women.


Asunto(s)
Difosfonatos/administración & dosificación , Osteoporosis Posmenopáusica/prevención & control , Fosfatasa Alcalina/sangre , Biomarcadores/sangre , Biomarcadores/orina , Densidad Ósea , Colágeno/sangre , Colágeno/orina , Colágeno Tipo I , República Checa , Difosfonatos/uso terapéutico , Relación Dosis-Respuesta a Droga , Método Doble Ciego , Esquema de Medicación , Femenino , Humanos , Ácido Ibandrónico , Inyecciones Intravenosas , Vértebras Lumbares , Persona de Mediana Edad , Noruega , Osteocalcina/sangre , Osteoporosis Posmenopáusica/metabolismo , Osteoporosis Posmenopáusica/fisiopatología , Hormona Paratiroidea/sangre , Péptidos/sangre , Péptidos/orina , Federación de Rusia , Estadísticas no Paramétricas
5.
Maturitas ; 44(3): 189-99, 2003 Mar 28.
Artículo en Inglés | MEDLINE | ID: mdl-12648882

RESUMEN

OBJECTIVE: Levormeloxifene is a selective estrogen receptor modulator (SERM). The development of the drug was discontinued due to intolerable adverse effects. This paper follow-up on the adverse events in a group of 234 women that was followed for 12 months without treatment after 12 months of treatment with levormeloxifene. METHODS: Adverse events were recorded at all clinical visits. The double-layer thickness of the uterine endometrium was determined by transvaginal ultrasonography. Endometrial biopsies were obtained by pipelle. The biopsies taken at the entrance to the follow-up phase were taken under hysteroscopy-guidance. Bone mineral density of the total body, lumbar spine (L1-L4), hip and forearm was measured by dual-energy X-ray absorptiometry. RESULTS: The most prominent adverse event was increased endometrial thickness over the pre-defined threshold of 8 mm. No cases of proliferative endometrium were reported. Following withdrawal of treatment the mean endometrial thickness approached baseline levels in a dose dependent manner. Hysteroscopic examinations showed that levormeloxifene was related to increased incidence of edema, vascularization and cysticity. In the levormeloxifene groups, a total of eight women had utero-vaginal prolapse and five women reported urinary incontinence (including worsening of a previously existing condition). Bone density in the spine and hip approached baseline levels during the 12 months of follow-up without treatment. CONCLUSION: Endometrial thickening, seen in association with the use of some SERM's, may lead to harmful adverse effects more than 12 months after treatment is initiated. Levormeloxifene prevents the postmenopausal bone loss, but the lowest effective dose is unknown.


Asunto(s)
Densidad Ósea/efectos de los fármacos , Pirrolidinas/efectos adversos , Moduladores Selectivos de los Receptores de Estrógeno/efectos adversos , Método Doble Ciego , Endometrio/efectos de los fármacos , Femenino , Estudios de Seguimiento , Humanos , Persona de Mediana Edad , Pirrolidinas/administración & dosificación , Pirrolidinas/uso terapéutico , Receptores de Estrógenos/agonistas , Seguridad , Moduladores Selectivos de los Receptores de Estrógeno/administración & dosificación , Moduladores Selectivos de los Receptores de Estrógeno/uso terapéutico , Síndrome de Abstinencia a Sustancias , Factores de Tiempo , Incontinencia Urinaria/inducido químicamente , Prolapso Uterino/inducido químicamente
6.
Am J Obstet Gynecol ; 184(2): 32-40, 2001 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-11174476

RESUMEN

OBJECTIVE: A total of 325 of 569 postmenopausal women who were initially recruited into two 2-year, double-blind, placebo-controlled, dose-ranging studies of a matrix transdermal formulation of 17beta-estradiol (Menorest) participated in open-label extensions for a third year. STUDY DESIGN: Those patients originally randomly assigned to receive 17beta-estradiol continued active treatment with dosages of 25, 50, 75, or 100 microg/d, whereas those originally randomly assigned to receive a placebo patch were switched to an active patch of identical size that delivered 17beta-estradiol at 25, 50, 75, or 100 microg/d. Follow-up was conducted, and bone density and other parameters were compared. RESULTS: Overall, gains in bone mass were maintained in patients who received 3 years of active treatment. In patients originally randomly assigned to receive placebo, initial losses in bone mass during the first 2 years were reversed and replaced with marked increases after the switch to active treatment. All patients who had initially received placebo showed significant, dose-related, clinically relevant increases (2.77% +/- 0.99%; P =.0048; to 7.36% +/- 0.74%; P =.0001) in lumbar spine bone mineral density relative to the end of the second year of the original study; smaller final-year increases were noted among the patients who had been actively treated for all 3 years. Similar trends were reported for femoral, trochanter, and total hip bone mineral densities. Mean total body bone mineral density either increased or remained unchanged in all dosage groups. These results were accompanied by parallel changes in levels of serum and urinary markers of bone turnover, with all markers approaching or returning to premenopausal levels by month 36. The high tolerability of this formulation during years 1 and 2 was maintained during year 3; 5.5% of patients withdrew from treatment because of adverse events in the final year. CONCLUSION: The Menorest formulation of transdermal 17beta-estradiol maintained bone mineral density gains in postmenopausal women and was well tolerated through a 3-year treatment period. It was also effective in reversing the initial bone loss associated with late commencement of therapy.


Asunto(s)
Estradiol/administración & dosificación , Osteoporosis Posmenopáusica/prevención & control , Posmenopausia , Absorciometría de Fotón , Administración Cutánea , Adulto , Densidad Ósea , Remodelación Ósea , Colágeno/orina , Colágeno Tipo I , Método Doble Ciego , Estradiol/efectos adversos , Estradiol/uso terapéutico , Femenino , Fémur , Estudios de Seguimiento , Cadera , Humanos , Vértebras Lumbares , Persona de Mediana Edad , Péptidos/orina , Placebos
7.
J Clin Endocrinol Metab ; 86(2): 755-60, 2001 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-11158042

RESUMEN

Three hundred and one healthy women between 45 and 65 yr of age and at least 1 yr postmenopausal were randomly assigned to 12-month double-blind therapy with levormeloxifene [1.25 (n = 51), 5, 10, or 20 mg/day], low dose continuous combined hormone replacement therapy [HRT; 1 mg 17 beta-estradiol and 0.5 mg norethisterone acetate/day], or placebo (all n = 50). All of the women were also given a daily supplement of calcium (500 mg). Serum CrossLaps decreased by about 50% in the levormeloxifene groups, with no dose-response effect. The group receiving HRT decreased more (>60%), and the placebo group (500 mg calcium alone) decreased by about 10%. The pattern was similar for bone alkaline phosphatase, except that the decreases were smaller, about 30% for the levormeloxifene groups and 50% for the HRT group. Serum osteocalcin also showed highly significant decreases, of the same magnitude in the levormeloxifene and HRT groups. Spinal bone mineral density (BMD) decreased by less than 1% in the placebo group and increased by about 2% in the levormeloxifene groups and by almost 5% in the HRT group (P < 0.001 for the difference between levormeloxifene and HRT vs. placebo). BMD of the total hip and total body changed in the same direction, although differences between groups were not as pronounced as those for BMD spine. Total cholesterol decreased by about 13--20% during levormeloxifene therapy, whereas daily doses of 1 mg estradiol and 0.5 mg norethisterone acetate produced a decrease of only about 8%. Levormeloxifene decreased low density lipoprotein cholesterol by about 22-30% compared with about 12% in the low dose HRT group. High density lipoprotein cholesterol was unchanged in all groups. Endometrial thickness increased both clinically and statistically significantly in the levormeloxifene groups independently of the dose; the difference from the placebo and HRT groups was significant (P < 0.001). There was no significant difference between the HRT and placebo groups. Other adverse events of interest include hot flushes, which did not occur more frequently in the levormeloxifene than the placebo groups, but occurred significantly less frequently in the HRT group (P < 0.05). Breast tenderness was much more common in the HRT group (<0.001) than in all other groups. In conclusion, the study shows that levormeloxifene, a new selective estrogen receptor modulator, has positive effects on BMD and bone turnover and apparently strong estrogenic effects on the serum concentrations of different cholesterol subfractions. Levormeloxifene at the doses tested had an estrogen-like effect on endometrium and no effect on hot flushes. The study was unable to differentiate between the effects of the different doses of levormeloxifene.


Asunto(s)
Densidad Ósea , Terapia de Reemplazo de Estrógeno , Lípidos/sangre , Osteoporosis Posmenopáusica/prevención & control , Pirrolidinas/uso terapéutico , Calcio/administración & dosificación , Calcio/uso terapéutico , Colesterol/sangre , Método Doble Ciego , Endometrio/citología , Endometrio/diagnóstico por imagen , Estradiol , Femenino , Humanos , Lipoproteínas/sangre , Persona de Mediana Edad , Noretindrona/análogos & derivados , Acetato de Noretindrona , Placebos , Pirrolidinas/efectos adversos , Receptores de Estrógenos/antagonistas & inhibidores , Triglicéridos/sangre , Ultrasonografía
8.
J Nutr ; 130(12): 2943-8, 2000 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-11110851

RESUMEN

Conjugated linoleic acid (CLA) has been shown to reduce body fat mass (BFM) in animals. To investigate the dose-response relationships of conjugated linoleic acid with regard to BFM in humans, a randomized, double-blind study including 60 overweight or obese volunteers (body mass index 25-35 kg/m(2)) was performed. The subjects were divided into five groups receiving placebo (9 g olive oil), 1.7, 3.4, 5.1 or 6.8 g conjugated linoleic acid per day for 12 wk, respectively. Dual-energy X-ray absorptiometry was used to measure body composition [measurements at wk 0 (baseline), 6 and 12]. Of the 60 subjects, 47 completed the study. Eight subjects withdrew from the study due to adverse events; however, no differences among treatment groups were found regarding adverse events. Repeated-measures analysis showed that a significantly higher reduction in BFM was found in the conjugated linoleic acid groups compared with the placebo group (P: = 0.03). The reduction of body fat within the groups was significant for the 3.4 and 6.8 g CLA groups (P: = 0.05 and P: = 0.02, respectively). No significant differences among the groups were observed in lean body mass, body mass index, blood safety variables or blood lipids. The data suggest that conjugated linoleic acid may reduce BFM in humans and that no additional effect on BFM is achieved with doses > 3.4 g CLA/d.


Asunto(s)
Tejido Adiposo/efectos de los fármacos , Composición Corporal/efectos de los fármacos , Ácido Linoleico/farmacología , Obesidad/tratamiento farmacológico , Absorciometría de Fotón , Adulto , Anciano , Relación Dosis-Respuesta a Droga , Método Doble Ciego , Femenino , Humanos , Ácido Linoleico/administración & dosificación , Masculino , Persona de Mediana Edad , Obesidad/prevención & control , Encuestas y Cuestionarios
9.
Eur J Endocrinol ; 143(2): 261-5, 2000 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-10913946

RESUMEN

Up to 85% of the variance in bone mineral density (BMD) is genetically determined. A putative candidate gene involved in the regulation of bone mass is the COLIA1 gene encoding type I collagen, which is the major protein of bone. We examined possible allelic influences of a G to T COLIA1 gene polymorphism in a recognition site for the transcription factor Sp1 on: (i) gain of forearm BMD using single photon absorptiometry (SPA); and (ii), BMD of the forearm, spine, hip, and whole body with dual X-ray absorptiometry (DXA). At baseline, 269 healthy boys and girls aged 8.2-16.5 years were eligible for the study. Forearm BMD measurements obtained at baseline and after 3.8+/-0.1 years (+/-s.d.) were used to calculate the annual percentage change in BMD. Calcium intake and physical activity were determined by a detailed questionnaire at baseline and after 1 year. Essentially no significant differences in forearm BMD gain or in BMD assessed at the forearm, spine, and whole body were observed among the three COLIA1 genotypes. In conclusion, the data indicate that the polymorphism at the Sp1 site in the COLIA1 gene is not associated with BMD or gain of forearm BMD in healthy boys and girls.


Asunto(s)
Colágeno/genética , Polimorfismo de Longitud del Fragmento de Restricción , Factor de Transcripción Sp1/metabolismo , Adolescente , Adulto , Sitios de Unión/genética , Densidad Ósea , Calcio de la Dieta/administración & dosificación , Niño , Cadena alfa 1 del Colágeno Tipo I , Ejercicio Físico/fisiología , Femenino , Genotipo , Humanos , Masculino , Estudios Prospectivos , Encuestas y Cuestionarios
10.
Osteoporos Int ; 9(4): 358-66, 1999.
Artículo en Inglés | MEDLINE | ID: mdl-10550454

RESUMEN

A total of 277 early postmenopausal women were enrolled in this placebo-controlled 2-year study to examine the efficacy of a matrix transdermal 17beta-estradiol system, at three different dosages (25, 50 and 75 mg/day) combined with sequential oral dydrogesterone 20 mg/day, in preventing bone loss. At 2 years, the difference from placebo in percentage change from baseline of L1-4 lumbar spine bone mineral density (BMD) (assessed by dual-energy X-ray absorptiometry) was 4.7% +/- 0.7% with estradiol 25 mg/day, 7.3% +/- 0.7% with estradiol 50 mg/day and 8.7% +/- 0.7% with estradiol 75 mg/day (all values mean +/- SEM). There were also significant increases in femoral neck, trochanter and total hip BMD with all doses of estradiol compared with placebo. Additionally, most patients had a significant gain (increase greater than 2.08%) in lumbar spine bone mass compared with placebo. Patients who received estradiol also experienced clinically significant and dose-related decreases in total serum osteocalcin, serum bone alkaline phosphatase and urinary C-telopeptide, with all three markers of bone turnover returning to premenopausal levels. Estradiol was well tolerated during the 2-year treatment period. Transdermal estradiol is effective and well tolerated at dosages between 25-75 mg/day in the prevention of bone loss in postmenopausal women; 25 mg/day offers an effective option for those women who cannot tolerate higher doses.


Asunto(s)
Estradiol/administración & dosificación , Osteoporosis Posmenopáusica/prevención & control , Administración Cutánea , Adulto , Fosfatasa Alcalina/sangre , Análisis de Varianza , Biomarcadores/sangre , Biomarcadores/orina , Densidad Ósea/efectos de los fármacos , Remodelación Ósea/efectos de los fármacos , Colágeno/orina , Colágeno Tipo I , Método Doble Ciego , Esquema de Medicación , Estradiol/uso terapéutico , Femenino , Humanos , Vértebras Lumbares , Persona de Mediana Edad , Osteocalcina/sangre , Osteoporosis Posmenopáusica/fisiopatología , Péptidos/orina
11.
Scand J Clin Lab Invest ; 57(7): 647-53, 1997 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-9397497

RESUMEN

The aim of this study was to investigate how reference handbooks distributed by hospital laboratories are used by medical doctors, and to what extent this kind of information can influence or change doctors' work habits. We also wanted to see if books with various contents of information are valued differently by the users, and we asked for preferences for an ideal book. A questionnaire was sent to 2075 medical doctors served by five Norwegian hospital laboratories. The overall response rate was 66%, of whom 76% had received a handbook. Seventy-eight percent of respondents who stated that they had received a handbook kept it in their consulting room and 45% used it once or more weekly. The majority (89%) found the books beneficial in their everyday work. Many doctors (36%) claimed that they had changed their routines as a result of the information in the book. The way of interpreting test results was influenced most often, followed by indications for ordering laboratory tests, sample collection and specimen handling, and patient preparation. Nearly all respondents (97%) felt that handbooks of this kind are beneficial to their technical and nursing staff. The results show that handbooks distributed by medical laboratories are well received, frequently used and highly appreciated by medical doctors. Comprehensive books are rated higher than smaller books.


Asunto(s)
Educación Médica Continua/métodos , Laboratorios de Hospital , Obras de Referencia , Estudios de Evaluación como Asunto , Conocimientos, Actitudes y Práctica en Salud , Humanos , Médicos
13.
Biochim Biophys Acta ; 876(3): 685-7, 1986 May 21.
Artículo en Inglés | MEDLINE | ID: mdl-3707992

RESUMEN

Liver CoA is markedly higher in hyperthyroid rats as compared to hypothyroid rats, and in fasted rats as compared to fed rats. In hyperthyroid rats the CoA is increased mainly in the cytosol, while in fasted rats the increase is mainly in the mitochondria. Malonyl-CoA is markedly higher in hypothyroid rats than in euthyroid and hyperthyroid rats. With fasting, malonyl-CoA drops 80-85% in all thyroid states. These findings are discussed in relation to the regulation of fatty acid oxidation in the liver.


Asunto(s)
Acilcoenzima A/metabolismo , Coenzima A/metabolismo , Ayuno , Hígado/metabolismo , Malonil Coenzima A/metabolismo , Glándula Tiroides/fisiología , Animales , Compartimento Celular , Citosol/metabolismo , Ácidos Grasos/metabolismo , Hipertiroidismo/metabolismo , Hipotiroidismo/metabolismo , Hígado/citología , Masculino , Mitocondrias Hepáticas/metabolismo , Oxidación-Reducción , Ratas , Ratas Endogámicas
14.
Anal Biochem ; 138(1): 107-11, 1984 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-6731835

RESUMEN

The malonyl-CoA assay was nonlinear at low malonyl-CoA concentrations when labeled acetyl-CoA was used as fatty acid synthase primer. Linearity was obtained with low concentrations of both fatty acid synthase and labeled acetyl-CoA, but then the assay was disturbed by the diluting effect of endogenous acetyl-CoA. The problems of nonlinearity and dilution of radioactivity by endogenous compounds were absent when labeled butyryl-CoA was used as primer. The levels of malonyl-CoA in rat heart, kidney, and liver were determined. The use of butyryl-CoA gave higher values of malonyl-CoA.


Asunto(s)
Acetilcoenzima A/metabolismo , Acilcoenzima A/análisis , Acilcoenzima A/metabolismo , Ácido Graso Sintasas/metabolismo , Malonil Coenzima A/análisis , Animales , Riñón/enzimología , Hígado/enzimología , Masculino , Miocardio/enzimología , Ratas , Ratas Endogámicas
15.
Biochim Biophys Acta ; 793(1): 1-9, 1984 Mar 27.
Artículo en Inglés | MEDLINE | ID: mdl-6704406

RESUMEN

Small amounts of glycerol (0.25 mM) simultaneously decrease oxidation and increase esterification of fatty acids in isolated rat hepatocytes, mainly by raising the intracellular concentration of alpha-glycerophosphate. These effects were obtained in all thyroid states as well as in the fed and fasted states. In normal hepatocytes, the rate of oxidation showed a poor correlation with the content of malonyl-CoA. The effects of glycerol on fatty acid metabolism were most pronounced in hepatocytes with a high capacity for esterification and a previous low concentration of alpha-glycerophosphate (glucagon-treated hepatocytes from euthyroid fed rats). Esterification capacity was influenced by the nutritional and thyroid state (decreased in fasting and in hyperthyroidism). It was not influenced by glucagon in short-term experiments. alpha-Glycerophosphate may not regulate fatty acid metabolism in vivo, but a high esterification capacity probably traps acyl-CoA for esterification, thus preventing fatty acids from being oxidized. The metabolism of alpha-glycerophosphate seems to be accelerated by hyperthyroidism and slowed down by fasting. The effect of fasting seems not to depend on thyroid hormones for its effects on fatty acid metabolism in the liver.


Asunto(s)
Ayuno , Ácidos Grasos/metabolismo , Glicerol/farmacología , Hígado/metabolismo , Glándula Tiroides/fisiología , Animales , Ésteres , Glicerofosfatos/metabolismo , Masculino , Oxidación-Reducción , Ácido Palmítico , Ácidos Palmíticos/metabolismo , Ratas
16.
Biochim Biophys Acta ; 750(2): 244-52, 1983 Feb 07.
Artículo en Inglés | MEDLINE | ID: mdl-6860680

RESUMEN

The activity of the outer carnitine palmitoyltransferase (EC 2.3.1.21) and the carnitine-dependent oxidation of palmitoyl-CoA was increased 3-4 fold in liver mitochondria from hyperthyroid rats as compared with hypothyroid rats. The inhibitory effect of malonyl-CoA on carnitine-dependent fatty acid oxidation was preserved in all thyroid states, but decreased in hyperthyroid mitochondria. Fasting for 24 h increased the activity of the outer carnitine palmitoyltransferase about 50% in hypothyroid liver mitochondria, whereas it had no significant effect in hyperthyroid mitochondria. The thyroid state had no significant effect on total carnitine palmitoyltransferase in liver mitochondria. Fasting stimulated fatty acid oxidation 3-4-fold in isolated hepatocytes from hypothyroid rats, whereas it had no effect in hyperthyroid rats. Feeding 0.3% clofibrate to euthyroid rats about doubled the activity of the total carnitine palmitoyltransferase, whereas it had no effect on the outer transferase. The regulation of fatty acid oxidation in the liver is discussed.


Asunto(s)
Aciltransferasas/metabolismo , Carnitina O-Palmitoiltransferasa/metabolismo , Ácidos Grasos/metabolismo , Hipertiroidismo/enzimología , Hipotiroidismo/enzimología , Hígado/metabolismo , Mitocondrias Hepáticas/enzimología , Glándula Tiroides/fisiología , Animales , Glucagón/farmacología , Técnicas In Vitro , Hígado/efectos de los fármacos , Masculino , Ratas , Ratas Endogámicas , Triyodotironina/farmacología
17.
Biochim Biophys Acta ; 711(1): 90-100, 1982 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-7066376

RESUMEN

1. The effect of triiodothyronine on the metabolism of palmitate, oleate and erucate in isolated rat hepatocytes was studied. 2. In triiodothyronine-treated rats increased oxidation and decreased triacylglycerol formation from palmitate and oleate was observed. For erucate triiodothyronine caused increased oxidation, but had no significant effect on esterification. 3. Glucagon had no effect on the fatty acid metabolism in hepatocytes from triiodothyronine-treated rats, whereas it stimulated the oxidation in hepatocytes from normal rats. Still, after treatment with triiodothyronine, the oxidation of fatty acids was significantly higher than in glucagon-stimulated normal hepatocytes. 4. In isolated rat liver mitochondria triiodothyronine raised the activity of the outer carnitine palmitoyltransferase (EC 2.3.1.21). The activity of the total carnitine palmitoyltransferase was elevated only slightly in isolated mitochondria from triiodothyronine-treated rats. These effects were similar to those seen in fasted rats. 5. Triiodothyronine had no significant influence on the concentration of long-chain acyl-CoA or alpha-glycerophosphate in isolated rat hepatocytes.


Asunto(s)
Ácidos Grasos/metabolismo , Hígado/metabolismo , Triyodotironina/farmacología , Animales , Carnitina O-Palmitoiltransferasa/metabolismo , Ayuno , Glucagón/farmacología , Glicerofosfatos/metabolismo , Hígado/efectos de los fármacos , Masculino , Mitocondrias Hepáticas/enzimología , Ratas , Ratas Endogámicas
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