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1.
West Afr J Med ; 41(2): 126-134, 2024 Feb 29.
Artículo en Inglés | MEDLINE | ID: mdl-38581673

RESUMEN

BACKGROUND: Hypertension is a leading cause of morbidity and mortality globally. Over a quarter of patients with hypertension have uncontrolled hypertension. Lifestyle modification has been shown to improve blood pressure control, thus measures that would help patients with hypertension achieve positive lifestyle modification would improve BP control. The study aims to determine the effect of motivational interviews on lifestyle modification and blood pressure control among patients with hypertension attending the Family Medicine Clinics of Irrua Specialist Teaching Hospital (ISTH), Irrua, Nigeria. METHODS: The proposed study will be a randomised control trial (PACTR202301917477205). About 212 adults between 18 and 65 years with hypertension presenting to the Family Medicine Clinics of ISTH will be randomised into intervention and control groups. The intervention group will be given a motivational interview (MI) on lifestyle modification at the start of the study and monthly for 6 months in addition to standard care for the management of hypertension. The control group will be given standard care for the management of hypertension only without MI and seen monthly for 6 months. Both groups will be assessed at baseline and 6 months. At baseline, a qualitative technique will be used to determine the reason for not adopting lifestyle modification. STUDY OUTCOME: The primary outcome shall be lifestyle modification at 6 months while the secondary outcome shall be blood pressure control at 6 months. CONCLUSION: Findings from the study will provide cost-effective ways of blood pressure control and reduction in the disease burden of hypertension in Nigeria.


CONTEXTE: L'hypertension est l'une des principales causes de morbidité et de mortalité à l'échelle mondiale. Plus d'un quart des patients hypertendus ont une hypertension non contrôlée. La modification du mode de vie a été démontrée pour améliorer le contrôle de la pression artérielle, ainsi les mesures qui aideraient les patients hypertendus à réaliser une modification positive de leur mode de vie amélioreraient le contrôle de la PA. L'étude vise à déterminer l'effet des entretiens motivationnels sur la modification du mode de vie et le contrôle de la pression artérielle chez les patients hypertendus fréquentant les cliniques de médecine familiale de l'hôpital spécialisé d'enseignement d'Irrua (ISTH), Irrua, Nigeria. MÉTHODES: L'étude proposée sera un essai contrôlé randomisé (PACTR202301917477205). Environ 212 adultes âgés de 18 à 65 ans atteints d'hypertension se présentant aux cliniques de médecine familiale de l'ISTH seront randomisés en groupes d'intervention et de contrôle. Le groupe d'intervention recevra un entretien motivationnel (EM) sur la modification du mode de vie au début de l'étude et mensuellement pendant 6 mois en plus des soins standard pour la prise en charge de l'hypertension. Le groupe témoin recevra uniquement les soins standard pour la prise en charge de l'hypertension sans EM et sera vu mensuellement pendant 6 mois. Les deux groupes seront évalués au départ et à 6 mois. Au début, une technique qualitative sera utilisée pour déterminer la raison de la non-adoption de la modification du mode de vie. RÉSULTAT DE L'ÉTUDE: Le critère de jugement principal sera la modification du mode de vie à 6 mois, tandis que le critère de jugement secondaire sera le contrôle de la pression artérielle à 6 mois. CONCLUSION: Les résultats de l'étude fourniront des moyens rentables de contrôle de la pression artérielle et de réduction de la charge de morbidité de l'hypertension au Nigeria. MOTS-CLÉS: hypertension, entretien motivationnel, modification du mode de vie, contrôle de la pression artérielle, médecine familiale.


Asunto(s)
Hipertensión , Entrevista Motivacional , Adulto , Humanos , Nigeria , Medicina Familiar y Comunitaria , Hipertensión/terapia , Estilo de Vida , Presión Sanguínea , Hospitales de Enseñanza , Ensayos Clínicos Controlados Aleatorios como Asunto
2.
Niger J Clin Pract ; 17(6): 678-82, 2014.
Artículo en Inglés | MEDLINE | ID: mdl-25385901

RESUMEN

BACKGROUND: Several international studies have shown that abuse or mistreatment is a regular phenomenon faced by medical students. However, there is limited information on medical student abuse/mistreatment in Nigeria. The study was therefore conducted to assess the prevalence and patterns of mistreatment experienced by Medical Students in the University of Calabar. MATERIALS AND METHODS: A descriptive cross-sectional study was conducted among 451 undergraduate medical trainees in the University of Calabar. Systematic sampling was used in recruiting participants into the study. A self-administered questionnaire was then employed to obtain information on patterns of mistreatment experienced by medical undergraduates. Data were analyzed using Statistical Package for Social Scientists version 19 and level of significance set at <0.05. RESULTS: More than a third (35.5%) of all respondents interviewed had experienced one or more forms of mistreatment during their training, with 38.5% of them experiencing it weekly. The most common form of mistreatment experienced was verbal abuse (52.5%), and the main perpetrators of these incidents were medical consultants, (18.6%) other cadre of doctors (17.3%) and lecturers (14.4%). Being in the clinical level of study and aged above 25 years were significantly associated with experiencing mistreatment in this study (P < 0.05). However, only 8.8% reported these incidents. CONCLUSION: With more than a third of undergraduate medical trainees experiencing mistreatment, development of appropriate strategies for the prevention and reduction of these incidents are strongly recommended.


Asunto(s)
Relaciones Interprofesionales , Mala Conducta Profesional/estadística & datos numéricos , Facultades de Medicina , Estudiantes de Medicina/psicología , Adulto , Estudios Transversales , Femenino , Humanos , Masculino , Nigeria , Prevalencia , Conducta Social , Estudiantes de Medicina/estadística & datos numéricos , Encuestas y Cuestionarios , Adulto Joven
3.
Nat Genet ; 21(1): 91-4, 1999 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-9916797

RESUMEN

Primary systemic carnitine deficiency (SCD; OMIM 212140) is an autosomal recessive disorder characterized by progressive cardiomyopathy, skeletal myopathy, hypoglycaemia and hyperammonaemia. SCD has also been linked to sudden infant death syndrome. Membrane-physiological studies have suggested a defect of the carnitine transport system in the plasma membrane in SCD patients and in the mouse model, juvenile visceral steatosis. Although the responsible loci have been mapped in both human and mouse, the underlying gene has not yet been identified. Recently, we cloned and analysed the function of a novel transporter protein termed OCTN2. Our observation that OCTN2 has the ability to transport carnitine in a sodium-dependent manner prompted us to search for mutations in the gene encoding OCTN2, SLC22A5. Initially, we analysed the mouse gene and found a missense mutation in Slc22a5 in jvs mice. Biochemical analysis revealed that this mutation abrogates carnitine transport. Subsequent analysis of the human gene identified four mutations in three SCD pedigrees. Affected individuals in one family were homozygous for the deletion of a 113-bp region containing the start codon. In the second pedigree, the affected individual was shown to be a compound heterozygote for two mutations that cause a frameshift and a premature stop codon, respectively. In an affected individual belonging to a third family, we found a homozygous splice-site mutation also resulting in a premature stop codon. These mutations provide the first evidence that loss of OCTN2 function causes SCD.


Asunto(s)
Carnitina/deficiencia , Proteínas Portadoras/genética , Proteínas de la Membrana/genética , Mutación , Proteínas de Transporte de Catión Orgánico , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Proteínas Portadoras/metabolismo , ADN Complementario , Femenino , Humanos , Iones , Masculino , Proteínas de la Membrana/metabolismo , Ratones , Datos de Secuencia Molecular , Linaje , Sodio , Miembro 5 de la Familia 22 de Transportadores de Solutos
4.
Cancer Res ; 60(3): 546-8, 2000 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-10676634

RESUMEN

LKB1 serine/threonine kinase is a gene for Peutz-Jeghers cancer predisposition syndrome. Most studies have detected a low frequency of LKB1 defects in sporadic cancer. A notable exception is a recent report describing frequent, mostly missense type, LKB1 mutations in Korean distal colorectal tumors. To clarify the role of LKB1 in colon cancer, we scrutinized 50 left-sided Korean and Finnish specimens. No somatic mutations were found. The seven Korean somatic missense mutations reported previously were functionally analyzed, and five were found not to alter LKB1 kinase activity. One of these changes was found to be a germ-line polymorphism. LKB1 involvement in distal colorectal cancer is not common.


Asunto(s)
Neoplasias Colorrectales/etiología , Síndrome de Peutz-Jeghers/genética , Proteínas Serina-Treonina Quinasas/genética , Quinasas de la Proteína-Quinasa Activada por el AMP , Neoplasias Colorrectales/genética , Humanos , Mutación Missense , Proteínas Quinasas/metabolismo
5.
Diabetes ; 48(9): 1794-800, 1999 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-10480610

RESUMEN

T-1095A and T-1095 are synthetic agents derived from phlorizin, a specific inhibitor of Na+-glucose cotransporters (SGLTs). Unlike phlorizin, T-1095 is absorbed into the circulation via oral administration, is metabolized to the active form, T-1095A, and suppresses the activity of SGLTs in the kidney. Orally administered T-1095 increases urinary glucose excretion in diabetic animals, thereby decreasing blood glucose levels. Indeed, the postprandial hyperglycemia after a meal load was shown to be suppressed by this compound in streptozotocin (STZ)-induced diabetic rats. With long-term T-1095 treatment, both blood glucose and HbA1c levels were reduced in STZ-induced diabetic rats and yellow KK mice. In addition, there was amelioration of abnormal carbohydrate metabolism, i.e., hyperinsulinemia and hypertriglyceridemia, and of the development of microalbuminuria, in yellow KK mice. Thus, T-1095 may be a useful antidiabetic drug, providing a novel therapeutic approach for diabetes.


Asunto(s)
Carbonatos/uso terapéutico , Diabetes Mellitus Experimental/tratamiento farmacológico , Glucosa/metabolismo , Glucósidos/uso terapéutico , Riñón/efectos de los fármacos , Proteínas de Transporte de Monosacáridos/antagonistas & inhibidores , Sodio/metabolismo , Administración Oral , Animales , Diabetes Mellitus Experimental/metabolismo , Perros , Humanos , Riñón/metabolismo , Masculino , Ratones , Proteínas de Transporte de Monosacáridos/metabolismo , Periodo Posprandial , Ratas , Ratas Sprague-Dawley , Xenopus
6.
Hum Mutat ; 15(1): 118, 2000 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-10612840

RESUMEN

Primary systemic carnitine deficiency (SCD) is an autosomal recessive disorder of fatty acid oxidation caused by defective cellular carnitine transport. The disease is characterized by metabolic derangement simulating Reye's syndrome, hypoglcaemia, progressive cardiomyopathy and skeletal myopathy. Recently, it was shown that SCD is caused by mutations in the organic cation/carnitine transporter OCTN2 (SLC22A5). We report two novel mutations, W283R and V446F, which are both missense mutations in an affected infant. In vitro expression studies demonstrated that both are actually function-loss mutations with virtually no uptake activity. This is the first report of compound heterozygosity for two missense mutations in a patient with SCD. Hum Mutat 15:118, 2000.


Asunto(s)
Carnitina/deficiencia , Proteínas Portadoras/genética , Proteínas de la Membrana/genética , Proteínas de Transporte de Catión Orgánico , Carnitina/metabolismo , Proteínas Portadoras/metabolismo , Línea Celular , Heterocigoto , Humanos , Lactante , Masculino , Proteínas de la Membrana/metabolismo , Mutagénesis Sitio-Dirigida , Mutación Missense , Miembro 5 de la Familia 22 de Transportadores de Solutos
7.
FEBS Lett ; 419(1): 107-11, 1997 Dec 08.
Artículo en Inglés | MEDLINE | ID: mdl-9426230

RESUMEN

cDNA for a novel proton/organic cation transporter, OCTN1, was cloned from human fetal liver and its transport activity was investigated. OCTN1 encodes a 551-amino acid protein with 11 transmembrane domains and one nucleotide binding site motif. It is strongly expressed in kidney, trachea, bone marrow and fetal liver and in several human cancer cell lines, but not in adult liver. When expressed in HEK293 cells, OCTN1 exhibited saturable and pH-dependent [3H]tetraethyl ammonium uptake with higher activity at neutral and alkaline pH than at acidic pH. Furthermore, treatment with metabolic inhibitors reduced the uptake, which is consistent with the presence of the nucleotide binding site sequence motif. Although its subcellular localization and detailed functional characteristics are not clear at present, OCTN1 appears to be a novel proton antiporter that functions for active secretion of cationic compounds across the renal epithelial brush-border membrane. It may play a role in the renal excretion of xenobiotics and their metabolites.


Asunto(s)
Proteínas Portadoras/genética , Regulación del Desarrollo de la Expresión Génica/fisiología , Proteínas de la Membrana/genética , Proteínas de Transporte de Membrana , Tetraetilamonio/metabolismo , Adenosina Trifosfato/fisiología , Adulto , Secuencia de Aminoácidos , Proteínas Portadoras/fisiología , Cationes , Línea Celular , Clonación Molecular , ADN Complementario/genética , Feto , Humanos , Concentración de Iones de Hidrógeno , Transporte Iónico/genética , Riñón , Cinética , Hígado , Proteínas de la Membrana/fisiología , Datos de Secuencia Molecular , Especificidad de Órganos , Proteínas de Transporte de Catión Orgánico , ARN Mensajero/análisis , Simportadores
8.
J Med Chem ; 42(26): 5311-24, 1999 Dec 30.
Artículo en Inglés | MEDLINE | ID: mdl-10639275

RESUMEN

In our studies of Na(+)-glucose cotransporter (SGLT) inhibitors as antidiabetic agents, a series of novel 4'-dehydroxyphlorizin derivatives substituted on the B ring was prepared and their effects on urinary glucose excretion were evaluated in rats. Introduction of only a small alkyl group at the 4'-position increased the activity, and 3-(benzo¿bfuran-5-yl)-2',6'-dihydroxy-4'-methylpropiophenone 2'-O-beta-D-glucopyranoside (4) showed the most potent effect. To overcome hydrolysis of compound 4 by beta-glucosidase in the digestive tract, the OH groups on the glucose moiety of compound 4 were modified. Three prodrugs (5, 42, and 55) were more potent than the parent compound 4 by oral administration, and finally 3-(benzo¿bfuran-5-yl)-2',6'-dihydroxy-4'-methylpropiophenone 2'-O-(6-O-methoxycarbonyl-beta-D-glucopyranoside) (5) was selected as a new promising candidate. Compound 5 was metabolized mainly by liver esterase to the active form (4), which was about 10 times more potent than 5 in inhibiting SGLT. In oral glucose tolerance test in db/db mice, compound 5 dose-dependently suppressed the elevation of glucose levels. Single administration of 5 reduced hyperglycemia concurrently with increase of glucose excretion into urine in diabetic KK-A(y) mice. Furthermore, compound 5 suppressed the elevation of blood glucose levels but did not lower it below the normal level even in fasted conditions in KK-A(y) mice. Additionally, long-term treatment with 5 dose-dependently reduced hyperglycemia and HbA1c in KK-A(y) mice. These pharmacological data strongly suggest that compound 5 has a therapeutic potential in the treatment of NIDDM.


Asunto(s)
Diabetes Mellitus Tipo 2/tratamiento farmacológico , Glucosa/síntesis química , Glucosa/farmacología , Hipoglucemiantes/farmacología , Glicoproteínas de Membrana/antagonistas & inhibidores , Proteínas de Transporte de Monosacáridos/antagonistas & inhibidores , Animales , Biotransformación , Glucemia/análisis , Perros , Glucosa/uso terapéutico , Hemoglobina Glucada/análisis , Haplorrinos , Humanos , Hipoglucemiantes/síntesis química , Hipoglucemiantes/uso terapéutico , Masculino , Ratones , Ratas , Ratas Sprague-Dawley , Transportador 1 de Sodio-Glucosa , Análisis Espectral , Relación Estructura-Actividad
9.
Br J Pharmacol ; 132(2): 578-86, 2001 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-11159708

RESUMEN

1. The therapeutic effects of an orally active inhibitor of Na(+)-glucose cotransporter (SGLT), T-1095 (a derivative of phlorizin; 3-(benzo[b]furan-5-yl)-2',6'-dihydroxy-4'-methylpropiophenone 2'-O-(6-O-methoxycarbonyl-beta-D-glycopyranoside)) were examined in C57BL/KsJ-db/db (db/db) mice, a genetic animal model of obese type 2 diabetes. 2. The higher renal SGLT activity in db/db mice than normoglycaemic C57BL/KsJ-db/+m (db/+m) mice may support the rationale for using an SGLT inhibitor in the treatment regimen for type 2 diabetes. Both T-1095 and its metabolite, T-1095A, which had approximately 10 times more potency, effectively inhibited renal SGLT activity of these mice in vitro. 3. Single oral administration of T-1095 (10, 30, 100 mg kg(-1), p.o.) to db/db mice caused a dose-dependent reduction in blood glucose levels and a concomitant increase in glucose excretion into urine. In contrast, T-1095 only slightly affected blood glucose levels in db/+m mice. 4. Chronic administration of T-1095 (0.1% w w(-1) pellet chow, for 12 weeks) decreased blood glucose and haemoglobin A(1C) levels, and improved glucose intolerance in db/db mice. The age-related decrease in plasma insulin levels was markedly inhibited and there was a 2.5 fold increase of insulin content in the pancreas of T-1095-treated db/db mice. Food consumption was not changed, while impaired body weight gain was ameliorated by T-1095 treatment. 5. Both the development of albuminuria and the expansion of glomerular mesangial area in db/db mice were significantly suppressed by chronic T-1095 treatment, indicating the prevention of the progression of diabetic nephropathy. 6. These results demonstrate that the SGLT inhibitor T-1095 is able to improve the metabolic abnormalities and inhibit the development of diabetic complications in db/db mice. Thus, T-1095 can be used for therapy of type 2 diabetic patients.


Asunto(s)
Carbonatos/uso terapéutico , Diabetes Mellitus Tipo 2/tratamiento farmacológico , Glucósidos/uso terapéutico , Hipoglucemiantes/uso terapéutico , Glicoproteínas de Membrana/antagonistas & inhibidores , Proteínas de Transporte de Monosacáridos/antagonistas & inhibidores , Animales , Glucemia/metabolismo , Diabetes Mellitus Tipo 2/sangre , Diabetes Mellitus Tipo 2/genética , Nefropatías Diabéticas/patología , Nefropatías Diabéticas/prevención & control , Glucagón/metabolismo , Prueba de Tolerancia a la Glucosa , Glucosuria/metabolismo , Insulina/metabolismo , Glomérulos Renales/patología , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Obesos , Microvellosidades/efectos de los fármacos , Microvellosidades/metabolismo , Páncreas/metabolismo , Fenotipo , Transportador 1 de Sodio-Glucosa
10.
Org Lett ; 3(21): 3309-12, 2001 Oct 18.
Artículo en Inglés | MEDLINE | ID: mdl-11594821

RESUMEN

[reaction: see text]. Phenylalanine-derived B-aryl-N-tosyloxazaborolidinones selectively activate one of two enantiotopic oxygen atoms in prochiral anti dioxane acetals derived from meso-1,3-diols, leading to enantioselective formation of ring-cleavage products. The reaction is utilized as a key step in asymmetric desymmetrization of meso-1,3-diols.

11.
Org Lett ; 3(13): 2101-3, 2001 Jun 28.
Artículo en Inglés | MEDLINE | ID: mdl-11418059

RESUMEN

[reaction: see text] O-(2-Naphthoyl)-N-tosyl-L-allo-threonine-derived B-phenyloxazaborolidinone catalyzes the asymmetric Mukaiyama-Michael addition of simple acyclic enones to give adducts of 54-85% ee. 2,6-Diisopropylphenol as an additive is demonstrated to effectively retard the undesirable Si(+)-catalyzed racemic pathway.

12.
Metabolism ; 49(8): 990-5, 2000 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-10954015

RESUMEN

The effect of T-1095, an inhibitor of renal glucose reabsorption, on hyperglycemia and the expression of Na+-glucose cotransporters (SGLTs) and facilitative glucose transporter 2 (GLUT2) in streptozotocin (STZ)-induced diabetic rats was examined. There was an elevation of blood glucose, hemoglobin A1c (HbA1c), kidney weight, and urinary excretion of both glucose and albumin in STZ rats. Administration of 0.03% and 0.1% (wt/wt diet) T-1095 to STZ rats for 4 weeks improved the hyperglycemia and dose-dependently decreased HbA1c. Moreover, treatment with 0.1% (wt/wt diet) T-1095 in STZ rats for 8 weeks not only reduced blood glucose and HbA1c, levels but also prevented the elevation of urinary albumin levels and kidney weight and the development of epithelial vacuolation. The expression of renal SGLT2, a major glucose transporter in the kidney, was not different in normal, STZ, and T-1095-treated STZ rats. In contrast, the elevated renal GLUT2 level in STZ rats was suppressed by T-1095. These data suggest that T-1095 improves hyperglycemia by suppressing the renal reabsorption of glucose, which results in a suppression of the development of functional and histological changes and abnormal expression of GLUT2 in the kidney.


Asunto(s)
Carbonatos/farmacología , Diabetes Mellitus Experimental/tratamiento farmacológico , Glucósidos/farmacología , Hiperglucemia/tratamiento farmacológico , Hipoglucemiantes/farmacología , Riñón/efectos de los fármacos , Proteínas de Transporte de Monosacáridos/antagonistas & inhibidores , Albuminuria/orina , Animales , Glucemia/efectos de los fármacos , Glucemia/metabolismo , Peso Corporal/efectos de los fármacos , Diabetes Mellitus Experimental/metabolismo , Diabetes Mellitus Experimental/orina , Transportador de Glucosa de Tipo 2 , Hemoglobina Glucada/metabolismo , Glucosuria/orina , Hiperglucemia/sangre , Hiperglucemia/metabolismo , Yeyuno/citología , Yeyuno/efectos de los fármacos , Yeyuno/metabolismo , Riñón/anatomía & histología , Riñón/metabolismo , Masculino , Proteínas de Transporte de Monosacáridos/biosíntesis , Tamaño de los Órganos/efectos de los fármacos , Ratas , Ratas Wistar , Transportador 2 de Sodio-Glucosa , Orina
13.
Eur J Pharmacol ; 391(1-2): 183-92, 2000 Mar 10.
Artículo en Inglés | MEDLINE | ID: mdl-10720650

RESUMEN

3-(Benzo[b]furan-5-yl)-2', 6'-dihydroxy-4'-methylpropiophenone-2'-O-(6-O-methoxycarbonyl)-bet a-D -glucopyranoside (T-1095) is a derivative of phlorizin, a potent inhibitor of Na(+)-glucose cotransporters. We determined the antidiabetic effect of T-1095 in neonatally streptozotocin-treated diabetic rats. Orally administered T-1095 is metabolized to an active form, 3-(benzo[b]furan-5-yl)-2', 6'-dihydroxy-4'-methylpropiophenone-2'-O-beta-D-glucopyranoside (T-1095A), which inhibits renal Na(+)-glucose cotransporters as potently as phlorizin in vitro. A single oral administration of T-1095 (30 and 100 mg/kg, p.o.) markedly lowered blood glucose levels with a concomitant increase in urinary glucose excretion; whereas the effect on blood glucose levels in non-diabetic rats was minimal. Continuous administration of T-1095 to diabetic rats for 6 weeks (0.1% in diet) improved not only hyperglycemia, but also the elevation of plasma free fatty acid and plasma ketone body levels. In addition, oral glucose tolerance testing clearly illustrated the improvement of glucose tolerance and insulin secretion with T-1095. In fact, amelioration of impaired insulin sensitivity in diabetic rats was demonstrated by the increase of whole-body and skeletal-muscle insulin-mediated glucose utilization with normalization of muscle glucose transporter (GLUT)4 content, and decrease of the hepatic glucose production rate. Consequently, polyuria and glucosuria were also improved in the T-1095-treated group. Therefore, T-1095 has a therapeutic potential as a means of ameliorating abnormal glucose metabolism via diminished glucose toxicity.


Asunto(s)
Animales Recién Nacidos/fisiología , Carbonatos/farmacología , Diabetes Mellitus Experimental/metabolismo , Glucósidos/farmacología , Hipoglucemiantes/farmacología , Proteínas de Transporte de Monosacáridos/antagonistas & inhibidores , Proteínas Musculares , Animales , Glucemia/metabolismo , Carbonatos/química , Glucosa/metabolismo , Técnica de Clampeo de la Glucosa , Prueba de Tolerancia a la Glucosa , Transportador de Glucosa de Tipo 1 , Transportador de Glucosa de Tipo 4 , Glucósidos/química , Glucosuria/metabolismo , Hipoglucemiantes/química , Insulina/metabolismo , Secreción de Insulina , Masculino , Microvellosidades/efectos de los fármacos , Microvellosidades/metabolismo , Proteínas de Transporte de Monosacáridos/metabolismo , Músculo Esquelético/efectos de los fármacos , Músculo Esquelético/metabolismo , Ratas , Ratas Sprague-Dawley , Sodio/metabolismo
14.
J Org Chem ; 65(7): 1899-906, 2000 Apr 07.
Artículo en Inglés | MEDLINE | ID: mdl-10774007

RESUMEN

Two types of bicyclic ortho esters 14 and 18, which are tethered to a diazocarbonyl group by polymethylene linkages--(CH2)n--of different lengths (n = 1-3 for 14 and 1-4 for 18), were prepared and catalytically decomposed by treatment with Rh2(OAc)4 either in the presence or absence of a protic nucleophile (MeOH, PhOH, AcOH) to give ring-enlargement product lactones 25 and 30 of different sizes. With 14, the enlargement took place when n = 1 or 2, but not when n = 3. With 18, in which the diazo carbon is substituted with a methoxycarbonyl group, the length of the chain can be extended further to n = 4 to obtain ring-enlargement products or their derivatives. All of these reactions could be explained in terms of the intermediacy of tricyclooxonium ylides 22 and 28. The ylides form an equilibrium with the corresponding ring-opened zwitterions 22' and 28', respectively, which, after protonation by a protic nucleophile, undergo mainly ring-enlargement to form medium-sized or large oxalactones rather than 1,2-rearrangement.

15.
J Org Chem ; 65(12): 3620-5, 2000 Jun 16.
Artículo en Inglés | MEDLINE | ID: mdl-10864744

RESUMEN

The reaction of 2-(3-diazo-2-oxopropane-1-yl)-2-methyldithiolane 9a, 2-(4-diazo-3-oxobutane-2-yl)-2-methyldithiolane 9c, and 2-(3-diazo-2-oxopropane-1-yl)-2-methyl-1,3-dithiane 9b with Rh(2)(OAc)(4) gave three-carbon ring-expansion products dithiocan-2-en-1-ones 13a, 13c and dithionan-2-en-1-one 13b, respectively. 2-(5-Diazo-4-oxopentyl)-2-methyldithiolane 9e also gave the five-carbon ring-expansion products dithionan-3-en-1-one 13e and 5-methylenedithionane-1-one 13'e. On the other hand, reaction of 2-(4-diazo-3-oxobutyl)-2-methyldithiolane 9d in the presence of AcOH gave the four-carbon ring-expansion product 16d substituted by an acetoxyl group. In addition, the reaction of 2-(3-diazo-2-oxopropyl)-2-methyl-3-oxathiolane 9f in the absence of AcOH gave 4-oxa-7-thiocan-2-en-1-one 19 via a sulfonium ylide intermediate, whereas, in the presence of AcOH, an alternative regioisomer 20 was also formed competitively with 19 via an oxonium ylide intermediate.

16.
J Org Chem ; 65(5): 1335-43, 2000 Mar 10.
Artículo en Inglés | MEDLINE | ID: mdl-10814093

RESUMEN

Sequential etherification of 2,2',6,6'-tetrahydroxybiphenyl (1) with 1,4-di-O-benzyl-L-threitol under Mitsunobu conditions gives desymmetrized biphenyldiol 9 of S-axial chirality exclusively. Cyclization of 9 with 1,omega-dibromoalkanes followed by removal of the chiral auxiliary yields (S)-2,2'-biphenyldiols 14 with alkylenedioxy bridges at the 6 and 6' positions. (S)-6,6'-Dialkyl- and -diphenyldiols 20 are obtained in an efficient manner via Pd(0)-catalyzed cross-coupling of bis(triflate) derivative 17 with organozinc reagents. Bis(triflate) 17 also serves as an intermediate for asymmetric synthesis of axially chiral biphenyldicarboxylic acid 23, terphenylcarboxylic acid 28, lactone 26, and lactam 30.

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