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1.
Clin Transplant ; 37(9): e15036, 2023 09.
Artículo en Inglés | MEDLINE | ID: mdl-37218656

RESUMEN

INTRODUCTION: Detection of alcohol (ETOH) use with biomarkers provides an opportunity to intervene and treat patients with alcohol use disorder before and after liver transplant (LT). We describe our center's experience using urine ethyl glucuronide (EtG) and serum phosphatidylethanol (PEth) in alcohol screening protocols. METHODS: Single-center, retrospective review of patients presenting for LT evaluation, patients waitlisted for LT for alcohol-associated liver disease (ALD), and patients who received a LT for ALD over a 12-month period, from October 1, 2019 through September 30, 2020. Patients were followed from waitlisting to LT, or for up to 12 months post-LT. We monitored protocol adherence to screening for ETOH use- defined as completion of all possible tests over the follow-up period- at the initial LT visit, while on the LT waitlist and after LT. RESULTS: During the study period, 227 patients were evaluated for LT (median age 57 years, 58% male, 78% white, 54.2% ALD). Thirty-one patients with ALD were placed on the waitlist, and 38 patients underwent LT for ALD during this time period. Protocolized adherence to screening for alcohol use was higher for PEth for all LT evaluation patients (191 [84.1%] vs. 146 [67%] eligible patients, p < .001), in patients with ALD waitlisted for LT (22 [71%] vs. 14 (48%] eligible patients, p = .04) and after LT for ALD, 20 (33 [86.8%] vs. 20 [52.6%] eligible patients, p < .01). Few patients with a positive test in any group completed chemical dependency treatment. CONCLUSIONS: When screening for ETOH use in pre- and post-LT patients, protocol adherence is higher using PEth compared to EtG. While protocolized biomarker screening can detect recurrent ETOH use in this population, engagement of patients into chemical dependency treatment remains challenging.


Asunto(s)
Alcoholismo , Hepatopatías Alcohólicas , Trasplante de Hígado , Humanos , Masculino , Persona de Mediana Edad , Femenino , Mejoramiento de la Calidad , Consumo de Bebidas Alcohólicas , Alcoholismo/diagnóstico , Etanol , Biomarcadores
2.
Climacteric ; 24(6): 600-604, 2021 12.
Artículo en Inglés | MEDLINE | ID: mdl-34236012

RESUMEN

OBJECTIVE: Hormone therapy (HT) is an effective treatment for menopause symptoms in select women. This study aimed to determine whether there is different prevalence of HT use based on patient report by women who see different provider specialties. METHODS: This study was a cross-sectional analysis of published data from the Survey of Midlife in the United States (MIDUS), a telephone or self-administered questionnaire of 3294 participants aged 39-90 years. Postmenopausal women were included. Self-reported HT use and provider specialty seen were each assessed by one question. Univariate logistic regression assessed factors possibly related to HT use. Variables with p < 0.1 were entered into a multivariable logistic regression model. RESULTS: Of the 938 postmenopausal respondents, 720 (76%) saw a gynecologist for care. One-hundred and thirty-one (13%) women used HT for menopausal symptoms. Of women using HT, 72 (55%) saw a gynecologist. When controlling for other factors, women who saw a gynecologist had three times higher odds of using HT. The most frequently seen provider specialty was not associated with use. CONCLUSIONS: Women who ever see a gynecologist are more likely to use HT for menopausal symptoms, but fewer women see gynecologists as they age. Generalists are the most seen provider specialty, positioning them to counsel patients about HT.


Asunto(s)
Terapia de Reemplazo de Estrógeno , Menopausia , Estudios Transversales , Femenino , Hormonas , Humanos , Medición de Resultados Informados por el Paciente , Estados Unidos
4.
Oncogene ; 26(28): 4049-58, 2007 Jun 14.
Artículo en Inglés | MEDLINE | ID: mdl-17224907

RESUMEN

Activator protein-2 (AP-2) is a transcription factor that regulates proliferation and differentiation in mammalian cells and has been implicated in the acquisition of the metastatic phenotype in several types of cancer. Herein, we examine the role of AP-2alpha in colon cancer progression. We provide evidence for the lack of AP-2alpha expression in the late stages of colon cancer cells. Re-expression of the AP-2alpha gene in the AP-2alpha-negative SW480 colon cancer cells suppressed their tumorigenicity following orthotopic injection into the cecal wall of nude mice. The inhibition of tumor growth could be attributed to the increased expression of E-cadherin and decreased expression and activity of matrix-metalloproteinase-9 (MMP-9) in the transfected cells, as well as a substantial loss of their in vitro invasive properties. Conversely, targeting constitutive expression of AP-2alpha in AP-2-positive KM12C colon cancer cells with small interfering RNA resulted in an increase in their invasive potential, downregulation of E-cadherin and increased expression of MMP-9. In SW480 cells, re-expression of AP-2alpha resulted in a fourfold increase in the activity of E-cadherin promoter, and a 5-14-fold decrease in the activity of MMP-9 promoter, indicating transcriptional regulation of these genes by AP-2alpha. Chromatin immunoprecipitation assay showed that re-expressed AP-2alpha directly binds to the promoter of E-cadherin, where it has been previously reported to act as a transcriptional activator. Furthermore, chromatin immunoprecipitation assay revealed AP-2alpha binding to the MMP-9 promoter, which ensued by decreased binding of transcription factor Sp-1 and changes in the recruitment of transcription factors to a distal AP-1 element, thus, contributing to the overall downregulation of MMP-9 promoter activity. Collectively, our data provide evidence that AP-2alpha acts as a tumor suppressor gene in colon cancer..


Asunto(s)
Cadherinas/fisiología , Neoplasias del Colon/metabolismo , Metaloproteinasa 9 de la Matriz/fisiología , Factor de Transcripción AP-2/fisiología , Animales , Línea Celular Tumoral , Neoplasias del Colon/enzimología , Neoplasias del Colon/patología , Regulación hacia Abajo , Humanos , Ratones , Ratones Desnudos , Factor de Transcripción AP-2/genética , Transfección , Regulación hacia Arriba
5.
Br J Cancer ; 93(2): 233-41, 2005 Jul 25.
Artículo en Inglés | MEDLINE | ID: mdl-15956974

RESUMEN

Neuropilin-1 (NRP-1) is a novel co-receptor for vascular endothelial growth factor (VEGF). Neuropilin-1 is expressed in pancreatic cancer, but not in nonmalignant pancreatic tissue. We hypothesised that NRP-1 expression by pancreatic cancer cells contributes to the malignant phenotype. To determine the role of NRP-1 in pancreatic cancer, NRP-1 was stably transfected into the human pancreatic cancer cell line FG. Signal transduction was assessed by Western blot analysis. Susceptibility to anoikis (detachment induced apoptosis) was evaluated by colony formation after growth in suspension. Chemosensitivity to gemcitabine or 5-fluorouracil (5-FU) was assessed by MTT assay in pancreatic cancer cells following NRP-1 overexpression or siRNA-induced downregulation of NRP-1. Differential expression of apoptosis-related genes was determined by gene array and further evaluated by Western blot analysis. Neuropilin-1 overexpression increased constitutive mitogen activated protein kinase (MAPK) signalling, possibly via an autocrine loop. Neuropilin-1 overexpression in FG cells enhanced anoikis resistance and increased survival of cells by > 30% after exposure to clinically relevant levels of gemcitabine and 5-FU. In contrast, downregulation of NRP-1 expression in Panc-1 cells markedly increased chemosensitivity, inducing > 50% more cell death at clinically relevant concentrations of gemcitabine. Neuropilin-1 overexpression also increased expression of the antiapoptotic regulator, MCL-1. Neuropilin-1 overexpression in pancreatic cancer cell lines is associated with (a) increased constitutive MAPK signalling, (b) inhibition of anoikis, and (c) chemoresistance. Targeting NRP-1 in pancreatic cancer cells may downregulate survival signalling pathways and increase sensitivity to chemotherapy.


Asunto(s)
Antineoplásicos Alquilantes/farmacología , Desoxicitidina/análogos & derivados , Desoxicitidina/farmacología , Fluorouracilo/farmacología , Proteínas Quinasas Activadas por Mitógenos/fisiología , Neuropilina-1/biosíntesis , Neuropilina-1/fisiología , Neoplasias Pancreáticas/patología , Apoptosis , Western Blotting , Resistencia a Antineoplásicos , Perfilación de la Expresión Génica , Humanos , Fenotipo , Transducción de Señal , Transfección , Células Tumorales Cultivadas , Regulación hacia Arriba , Gemcitabina
6.
Med Hypotheses ; 64(1): 159-61, 2005.
Artículo en Inglés | MEDLINE | ID: mdl-15533634

RESUMEN

Two decades ago, Crary reported his anecdotal observation that a supplemental antioxidant regimen including high-dose selenium (500 mcg daily) appeared to slow the progression of visual loss in diabetic retinopathy and macular degeneration. Recently, selenium has been shown to down-regulate VEGF production by rodent cancer cells, both in vivo and in vitro; this effect is dose-dependent and, like the anticarcinogenic activity of selenium, is mediated by methyselenol. If increased selenium exposure can likewise suppress VEGF production in the hypoxic retina, a straightforward explanation for Crary's observation may be at hand. Since selenium is inexpensive and non-toxic in the dose employed by Crary, an effort to replicate his findings is warranted.


Asunto(s)
Hipoxia de la Célula/efectos de los fármacos , Retinopatía Diabética/tratamiento farmacológico , Retinopatía Diabética/metabolismo , Suplementos Dietéticos , Modelos Biológicos , Retina/metabolismo , Selenio/administración & dosificación , Factor A de Crecimiento Endotelial Vascular/metabolismo , Administración Oral , Animales , Relación Dosis-Respuesta a Droga , Regulación hacia Abajo/efectos de los fármacos , Humanos , Retina/efectos de los fármacos , Resultado del Tratamiento
7.
J Dermatolog Treat ; 15(5): 295-302, 2004 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-15370397

RESUMEN

BACKGROUND: Erythromycin is a common therapy for acne and rosacea. A newer macrolide, azithromycin, offers superior tissue distribution and cellular concentration and is an effective oral anti-acne agent. Topical formulations such as erythromycin have been a major clinical therapy for acne. To date, no topical solution of azithromycin is available for the treatment of acne. OBJECTIVE: To prepare a stable topical 2% azithromycin formulation that could be used in an acne clinical trial to determine the efficacy of topical azithromycin in treating subjects with acne vulgaris and acne rosacea. METHODS: The study was divided into two phases. In phase I, azithromycin was prepared over a range of ethanol/water concentrations to determine solubility. The stability of a 2% azithromycin in 60% ethanol/water preparation was assessed by high-pressure liquid chromatography. The temperature, light, and pH dependence of the stability was also assessed. In phase II, a single center, randomized, double-blind, treatment-controlled study compared once-nightly application of topical 2% azithromycin versus 2% erythromycin. A total of 20 subjects with moderate inflammatory acne and 20 with rosacea were examined clinically at 0, 2, 4, 8, and 12 weeks for a 12-week period. Efficacy was evaluated with the Physician's Visual Analog Scale evaluation (PVAS), the papulopustule count, and acne severity rating (in subjects with acne). RESULTS: In phase I, azithromycin was soluble in 60% ethanol/water. A 2% azithromycin in 60% ethanol/water solution maintained stability at room temperature for up to 26 weeks but at 37 degrees C there was some decay (16%) at 26 weeks. The stability was greatest at pH 6.8 and was unaffected by ambient light exposure. In phase II, the number of inflammatory lesions decreased in both acne and rosacea subjects treated with 2% erythromycin (7.56, p=0.03 and 4.4, p=0.01, respectively). Azithromycin was not as effective for the treatment of rosacea. Both azithromycin (p=0.01) and erythromycin (p=0.03) treatment significantly reduced the inflammatory lesion count in acne vulgaris. No significant adverse events were identified in the acne group. In patients with rosacea, transient irritation occurred in five patients. CONCLUSIONS: A 2% azithromycin in 60% ethanol/water solution can be prepared and is stable for at least 6 months at room temperature. The methodology and power of the study were adequate to identify improvement in acne vulgaris and rosacea. Though it appears the formulation of topical azithromycin was at least comparable with topical erythromycin, larger studies would be needed to determine whether topical azithromycin has any significant advantage over topical erythromycin.


Asunto(s)
Acné Vulgar/tratamiento farmacológico , Antibacterianos/administración & dosificación , Azitromicina/administración & dosificación , Rosácea/tratamiento farmacológico , Acné Vulgar/patología , Administración Tópica , Adolescente , Adulto , Antibacterianos/efectos adversos , Azitromicina/efectos adversos , Química Farmacéutica , Niño , Método Doble Ciego , Estabilidad de Medicamentos , Eritromicina/administración & dosificación , Femenino , Humanos , Masculino , Rosácea/patología , Soluciones
8.
Br J Cancer ; 90(8): 1620-6, 2004 Apr 19.
Artículo en Inglés | MEDLINE | ID: mdl-15083195

RESUMEN

Eph receptor tyrosine kinases (RTKs) and their membrane-bound ligands, the ephrins, are essential for embryonic vascular development. Recently, it has been demonstrated that overexpression of specific Ephs and ephrins is associated with a poor prognosis in human tumours. Our group has shown that EphB and the ephrin-B subfamilies are coexpressed in human colorectal cancer, and ephrin-B2 is expressed at higher levels in human colorectal cancer than in adjacent normal mucosa. As the Eph/ephrin system is involved in embryologic vasculogenesis and ephrin-B2 is expressed ubiquitously in all colon cancers studied in our laboratory, we hypothesised that overexpression of ephrin-B2 in colon cancer cells may induce tumour angiogenesis and increase tumour growth. To investigate this hypothesis, we stably transfected KM12L4 human colon cancer cells with ephrin-B2 to study its effect on tumour growth in vivo. We found that overexpression of ephrin-B2 markedly decreased tumour growth in a mouse xenograft model. Immunohistochemical staining showed that ephrin-B2 transfectants produced higher tumour microvessel density and lower tumour cell proliferation than did parental or vector-transfected control cells. Using (51)Cr-labelled red blood cells (RBCs) to determine the functional blood volume in tumours, we demonstrated that tumours from ephrin-B2-transfected cells had significantly decreased blood volume compared with tumours from parental or vector-transfected control cells. Evaluation of in vitro parameters of cell cycle mediators demonstrated no alteration in the cell cycle. Although ephrin-B2 transfection increased tumour vessel density, the decrease in blood perfusion suggests that these vessels may be 'dysfunctional'. We conclude that overexpression of ephrin-B2 suppresses tumour cell growth and vascular function in this in vivo colon cancer model.


Asunto(s)
Neoplasias del Colon/genética , Neoplasias del Colon/patología , Efrina-B2/biosíntesis , Perfilación de la Expresión Génica , Regulación Neoplásica de la Expresión Génica , Neovascularización Patológica , Animales , Northern Blotting , Ciclo Celular , División Celular , Efrina-B2/análisis , Humanos , Inmunohistoquímica , Ligandos , Ratones , Ratones Desnudos , Neoplasias Experimentales , Proteínas Tirosina Quinasas/farmacología , Transfección , Células Tumorales Cultivadas
9.
Br J Cancer ; 90(3): 705-11, 2004 Feb 09.
Artículo en Inglés | MEDLINE | ID: mdl-14760388

RESUMEN

The purpose of this study was to examine the effects of ZD6126, a novel vascular-targeting agent, on tumour growth and angiogenesis in an orthotopic model of gastric cancer. TMK-1 human gastric adenocarcinoma cells were injected into the gastric wall of nude mice. After the tumours were established (day 14), therapy was initiated. Mice (n=11-12/group) received (a). vehicle, (b). ZD6126 at 100 mg x kg day(-1) i.p. one time per week or (c) ZD6126 at 100 mg x kg day(-1) i.p. five times per week. Tumour mass, volume and the presence or absence of peritoneal carcinomatosis were determined at sacrifice on day 38. Tumours from each group were stained for markers of blood vessels, proliferation and apoptosis. To further define the time frame of the vascular-targeting effects of chronic therapy with ZD6126, TMK-1 cells were again injected into the gastric wall of mice in a second experiment. On day 14, a single i.p. injection of ZD6126 100 mg x kg(-1) mouse(-1) or vehicle was delivered. Groups of three mice each were killed and the tumours harvested at days 1, 3 and 5 post-ZD6126 injection. Tumours were processed and stained for endothelial and tumour cell apoptosis and proliferation. No overt toxicity was observed with ZD6126 therapy. ZD6126 led to a marked inhibition of tumour growth (82% decrease vs control (P<0.001)). ZD6126 also led to a significant decrease in the incidence of peritoneal carcinomatosis (10 out of 12 controls, vs one out of 12 ZD6126) (P<0.01). Histological analysis of tumours revealed large regions of central necrosis in the treated group, as well as a dramatic increase in tumour cell apoptosis (7.4-fold increase (P<0.001)), consistent with the vascular-targeting activity of ZD6126. Mice treated with ZD6126 demonstrated a 59% decrease in PCNA-positive cells (P< 0.02), indicating reduced tumour cell proliferation. In addition, tumours treated with ZD6126 exhibited a 40% decrease in microvessel density (P<0.05). Results from mice treated with a single injection of ZD6126 demonstrated the acute effects this agent has on the tumour vasculature. The ratio of endothelial cell apoptosis to endothelial cell proliferation was increased within 24 h of a single injection. In conclusion, ZD6126 significantly inhibited tumour growth and metastasis in an orthotopic model of human gastric adenocarcinoma, without detectable problematic adverse effects. These data suggest that ZD6126 may be worthy of investigation in the treatment of primary gastric adenocarcinoma.


Asunto(s)
Adenocarcinoma/patología , Metástasis de la Neoplasia/fisiopatología , Neovascularización Patológica , Compuestos Organofosforados/farmacología , Neoplasias Peritoneales/secundario , Neoplasias Gástricas/fisiopatología , Animales , Apoptosis , División Celular , Modelos Animales de Enfermedad , Progresión de la Enfermedad , Células Endoteliales , Humanos , Ratones , Ratones Desnudos , Células Tumorales Cultivadas
10.
Med Hypotheses ; 62(1): 62-71, 2004.
Artículo en Inglés | MEDLINE | ID: mdl-14729006

RESUMEN

A new category of anti-anginal drug - exemplified by ranolazine - is believed to work by partially inhibiting cardiac oxidation of fatty acids; oxidation of glucose requires less oxygen per mol of ATP generated, and thus is preferable to fat oxidation when oxygen availability is limiting in underperfused cardiac tissue. Unfortunately, there is no reason to believe that these drugs inhibit fat oxidation selectively in the heart; thus, chronic use of these drugs can be expected to increase body fat stores until the original rate of fat oxidation is restored by mass action - presumably negating the therapeutic benefit in angina, while exacerbating the manifold adverse effects of insulin resistance syndrome. The rational way to decrease cardiac metabolic reliance on fatty acids is to consume a very-low-fat quasi-vegan diet (i.e., 10% fat calories). Indeed, such diets are known to have a rapid and substantial therapeutic impact on anginal symptoms, while concurrently benefiting insulin sensitivity, markedly improving serum lipid profile, promoting leanness, and lessening coronary risk. A reduction in diurnal insulin secretion might also be achieved, which would be expected to decrease sympathetic activity. While reduced myocardial demand for oxygen doubtless contributes to the beneficial impact of such diets on angina, it is likely that improved cardiac perfusion consequent to improved endothelium-dependent vasodilation also plays a role in this regard. Supplemental carnitine, also beneficial in angina, appears to improve utilization of glucose in the ischemic myocardium by lowering elevated acetyl-coA levels and thereby disinhibiting pyruvate dehydrogenase. Certain other nutraceuticals may aid control of angina by improving endothelial function. In the longer term, these measures have the potential to slow or reverse the progression of stenotic lesions that underlie most cases of angina. These safe and relatively inexpensive nutritional strategies for coping with angina deserve far more attention than orthodox medical practice has thus far accorded them.


Asunto(s)
Angina de Pecho/prevención & control , Angina de Pecho/fisiopatología , Dieta con Restricción de Grasas/métodos , Dieta Vegetariana , Endotelio Vascular/fisiopatología , Ácidos Grasos/metabolismo , Sistema Nervioso Simpático/fisiopatología , Acetanilidas , Carnitina/uso terapéutico , Quimioterapia Adyuvante/métodos , Inhibidores Enzimáticos/uso terapéutico , Corazón/inervación , Corazón/fisiopatología , Humanos , Piperazinas/uso terapéutico , Ranolazina
11.
Med Hypotheses ; 61(5-6): 543-60, 2003.
Artículo en Inglés | MEDLINE | ID: mdl-14592785

RESUMEN

Although exposure to ultraviolet light is often viewed as pathogenic owing to its role in the genesis of skin cancer and skin aging, there is growing epidemiological evidence that such exposure may decrease risk for a number of more serious cancers, may have a favorable impact on blood pressure and vascular health, and may help to prevent certain autoimmune disorders - in addition to its well-known influence on bone density. Most likely, these health benefits are reflective of improved vitamin D status. Increased synthesis or intake of vitamin D can be expected to down-regulate parathyroid hormone (PTH), and to increase autocrine synthesis of its active metabolite calcitriol in certain tissues; these effects, in turn, may impact cancer risk, vascular health, immune regulation, and bone density through a variety of mechanisms. Presumably, a truly adequate supplemental intake of vitamin D - manyfold higher than the grossly inadequate current RDA - could replicate the benefits of optimal UV exposure, without however damaging the skin. Diets moderately low in bioavailable phosphate - like many vegan diets - might be expected to have a complementary impact on disease risks, inasmuch as serum phosphate suppresses renal calcitriol synthesis while up-regulating that of PTH. A proviso is that the impact of dietary phosphorus on bone health is more equivocal than that of vitamin D. Increased intakes of calcium, on the other hand, down-regulate the production of both PTH and calcitriol - the latter effect may explain why the impact of dietary calcium on cancer risk (excepting colon cancer), hypertension, and autoimmunity is not clearly positive. An overview suggests that a vegan diet supplemented with high-dose vitamin D should increase both systemic and autocrine calcitriol production while suppressing PTH secretion, and thus should represent a highly effective way to achieve the wide-ranging health protection conferred by optimal UV exposure.


Asunto(s)
Dieta Vegetariana , Fosfatos/fisiología , Rayos Ultravioleta , Autoinmunidad , Calcitriol/metabolismo , Calcio/metabolismo , Calcio de la Dieta , Regulación hacia Abajo , Humanos , Luz , Modelos Teóricos , Hormona Paratiroidea/biosíntesis , Hormona Paratiroidea/metabolismo , Fósforo/metabolismo , Fósforo Dietético , Riesgo , Vitamina D/metabolismo , Vitamina D/fisiología
12.
Med Hypotheses ; 61(5-6): 561-6, 2003.
Artículo en Inglés | MEDLINE | ID: mdl-14592786

RESUMEN

In HIV patients, chronic treatment with protease inhibitors often precipitates a peripheral lipodystrophy associated with insulin resistance syndrome and premature coronary disease. In vitro studies demonstrate that these drugs can compromise the ability of adipocytes to store triglycerides; in vivo, peripheral subcutaneous adipocytes appear to be most affected, such that body fat often redistributes to visceral or truncal adipose stores. Dysfunction of peripheral subcutaneous adipocytes - ordinarily quite efficient for storing fat - can be expected to give rise to an excessive flux of free fatty acids (FFAs) following fatty meals; chronic overexposure of tissues to FFAs is a likely explanation for the insulin resistance syndrome associated with lipodystrophy. These considerations suggest that a very-low-fat diet - less than 15% fat calories - may ameliorate the cardiovascular risk associated with lipodystrophy; such diets are known to have a favorable effect on the insulin sensitivity of healthy subjects. Very-low-fat whole-food vegan diets are particularly recommendable in this context, as they may help to shrink visceral fat depots while markedly reducing LDL cholesterol. Appropriate adjunctive measures may include aerobic exercise training - beneficial both for insulin sensitivity and weight control - as well as administration of statins or policosanol, and of fibrates or fish oil, to decrease LDL and triglycerides, respectively. Despite perceptions to the contrary, very-low-fat diets can meet with good compliance in well-motivated subjects given appropriate instruction.


Asunto(s)
Dieta con Restricción de Grasas , Infecciones por VIH/complicaciones , Enfermedad Iatrogénica , Lipodistrofia/etiología , Adipocitos/metabolismo , LDL-Colesterol/metabolismo , Dieta Vegetariana , Humanos , Resistencia a la Insulina , Modelos Teóricos , Periodo Posprandial , Inhibidores de Proteasas/farmacología
13.
Med Hypotheses ; 61(5-6): 567-73, 2003.
Artículo en Inglés | MEDLINE | ID: mdl-14592787

RESUMEN

There is growing evidence that increases in both hematocrit and body iron stores are components of the insulin resistance syndrome. The ability of insulin and of IGF-I - whose effective activity is increased in the context of insulin resistance - to boost activity of the transcription factor hypoxia-inducible factor-1alpha (HIF-1alpha), may be at least partially responsible for this association. HIF-1alpha, which functions physiologically as a detector of both hypoxia and iron-deficiency, promotes synthesis of erythropoietin, and may also mediate the up-regulatory impact of hypoxia on intestinal iron absorption. Insulin/IGF-I may also influence erythropoiesis more directly, as they are growth factors for developing reticulocytes. Conversely, the activation of HIF-1alpha associated with iron deficiency may be responsible for the increased glucose tolerance noted in iron-deficient animals; HIF-1alpha promotes efficient glucose uptake and glycolysis - a sensible adaptation to hypoxia - by inducing increased synthesis of glucose transporters and glycolytic enzymes. Recent reports that phlebotomy can increase the efficiency of muscle glucose uptake in lean healthy omnivores are intriguing and require further confirmation. Whether increased iron stores contribute to the elevated vascular risk associated with insulin resistance is doubtful, inasmuch as most prospective studies fail to correlate serum ferritin or transferrin saturation with subsequent vascular events. However, current data are reasonably consistent with the possibility that moderately elevated iron stores are associated with increased overall risk for cancer - and for colorectal cancer in particular; free iron may play a catalytic role in 'spontaneous' mutagenesis. Thus, iron excess may mediate at least some of the increased cancer risk associated with insulin resistance and heme-rich diets. People who are insulin resistant can minimize any health risk associated with iron overload by avoiding heme-rich flesh foods and donating blood regularly.


Asunto(s)
Hematócrito , Hiperinsulinismo , Hierro/farmacocinética , Factores de Transcripción/biosíntesis , Regulación hacia Arriba , Eritropoyesis , Glucosa/metabolismo , Humanos , Hipoxia , Subunidad alfa del Factor 1 Inducible por Hipoxia , Insulina/metabolismo , Resistencia a la Insulina , Hierro/metabolismo , Modelos Teóricos , Músculos/metabolismo , Estudios Prospectivos , Reticulocitos/metabolismo
14.
Med Hypotheses ; 61(5-6): 535-42, 2003.
Artículo en Inglés | MEDLINE | ID: mdl-14592784

RESUMEN

Increased free intracellular calcium ([Ca(2+)](i)) in adipocytes blunts the lipolytic response to catecholamines by activating phosphodiesterase 3B - the same enzyme that mediates the antilipolytic effect of insulin - while also compromising the efficiency of insulin-stimulated glucose uptake. Physiological increases in parathyroid hormone (PTH) have been shown to increase [Ca(2+)](i) in adipocytes. These considerations may rationalize recent evidence that high dietary intakes of calcium and/or dairy products may reduce risk for obesity, diabetes, and insulin-resistance syndrome, and they predict that other dietary measures which down-regulate PTH - such as good vitamin D status, and moderation in phosphate and salt intakes - may likewise be beneficial in these respects. Consistent with this position are reports that body weight is elevated in elderly subjects with both primary and secondary hyperparathyroidism; furthermore, insulin resistance is a well-known complication of both forms of hyperparathyroidism. The fact that regular alcohol consumption is associated with decreased PTH secretion may help to explain why moderate drinkers are less prone to insulin resistance, diabetes, and - in women - obesity. Down-regulation of PTH cannot be expected to promote dramatic weight loss, but in the long-term it may lessen risk for significant weight gain and diabetes, and conceivably may potentiate the fat loss achievable with caloric restriction and/or exercise.


Asunto(s)
Consumo de Bebidas Alcohólicas , Peso Corporal/efectos de los fármacos , Calcio/metabolismo , Catecolaminas/antagonistas & inhibidores , Hormona Paratiroidea/fisiología , Vitamina D/metabolismo , Aumento de Peso , Adipocitos/metabolismo , Calcitriol/fisiología , Regulación hacia Abajo , Femenino , Humanos , Lipólisis , Masculino , Modelos Teóricos , Obesidad/etiología , Hormona Paratiroidea/biosíntesis
15.
J Dermatolog Treat ; 14(3): 136-40, 2003 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-14522622

RESUMEN

BACKGROUND: Hand and foot eczema is a chronic skin disorder. Although topical corticosteroids are often used to control the predominant symptoms of the disease, the chronicity of the condition increases the risk of long-term adverse effects. A safer alternative is needed. OBJECTIVE: To evaluate the safety and efficacy of tacrolimus ointment 0.1% in hand and/or foot eczema. METHODS: Twenty-five adults applied tacrolimus ointment 0.1% to affected areas three times daily for 8 weeks and were followed for 2 additional weeks. RESULTS: Except for vesiculation, compared with baseline there were significant improvements in erythema, scaling, induration, fissuring, composite severity, and pruritus (p<0.007). Two weeks after discontinuing treatment, significant improvement in scaling and composite severity (p<0.03) persisted, whereas erythema, induration, vesiculation, fissuring, and pruritus had returned to pre-treatment levels. CONCLUSION: Tacrolimus ointment 0.1% is a promising corticosteroid alternative for hand/foot eczema.


Asunto(s)
Eccema/tratamiento farmacológico , Dermatosis del Pie/tratamiento farmacológico , Dermatosis de la Mano/tratamiento farmacológico , Inmunosupresores/uso terapéutico , Tacrolimus/uso terapéutico , Administración Tópica , Adulto , Femenino , Humanos , Inmunosupresores/administración & dosificación , Masculino , Persona de Mediana Edad , Proyectos Piloto , Estadísticas no Paramétricas , Tacrolimus/administración & dosificación , Resultado del Tratamiento
16.
Med Hypotheses ; 61(4): 417-8, 2003 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-13679004

RESUMEN

There is recent evidence that nitric oxide blocks IL-6 signaling in hepatocytes by inhibiting activation of Stat3. If this effect is mediated by cGMP, then high-dose biotin--which can directly activate guanylyl cyclase--may have the potential to suppress hepatic production of acute phase proteins.


Asunto(s)
Reacción de Fase Aguda , Biotina/farmacología , Regulación hacia Abajo , Óxido Nítrico/metabolismo , Animales , Biotina/metabolismo , Células Cultivadas , GMP Cíclico/metabolismo , Proteínas de Unión al ADN/metabolismo , Humanos , Inflamación , Interleucina-6/antagonistas & inhibidores , Hígado/enzimología , Modelos Teóricos , Ratas , Factor de Transcripción STAT3 , Transducción de Señal , Transactivadores/metabolismo
17.
Med Hypotheses ; 61(4): 458-62, 2003 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-13679012

RESUMEN

A common polymorphism of the 54th codon of fatty acid-binding protein 2 (FABP2), in which threonine substitutes for alanine (T54), has been linked to insulin resistance and/or increased postprandial triglycerides in various studies. I propose that, in subjects expressing T54, the secretion of gastric inhibitory polypeptide (GIP) evoked by fatty meals is subnormal, such that adipocytes are less efficient in converting chylomicrons to stored triglyceride. The increased postprandial free fatty acid flux which this may imply could be expected to exacerbate insulin resistance syndrome--thus accounting for the association of T54 with insulin resistance in epidemiological studies. If this thesis proves to be correct, it will help to clarify the importance of appropriate GIP secretion to maintenance of insulin sensitivity in the context of fatty diets.


Asunto(s)
Proteínas Portadoras/genética , Grasas de la Dieta , Polipéptido Inhibidor Gástrico/metabolismo , Insulina/metabolismo , Polimorfismo Genético , Proteínas Supresoras de Tumor , Alanina/química , Alelos , Proteína de Unión a los Ácidos Grasos 7 , Proteínas de Unión a Ácidos Grasos , Humanos , Modelos Teóricos , Triglicéridos/química
18.
Med Hypotheses ; 61(4): 509-11, 2003 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-13679021

RESUMEN

During angiostatic therapy, tumor hypoxia will activate the transcription factor hypoxia-inducible factor-1alpha (HIF-1alpha), and will select for mutations which up-regulate the activity of this factor. This adaptation will increase tumor angiogenic capacity, while aiding the survival of poorly nourished cancer cells. A further effect of HIF-1alpha is to increase expression of transferrin receptors. The natural antimalarial drug artemisinin is selectively toxic to iron-loaded cells (such as malarial parasites), and it has recently been suggested that, inasmuch as many cancers overexpress transferrin receptors, such cancers might be treatable with a regimen comprised of iron supplementation and high-dose artemisinin. Thus, it can be anticipated that many tumors which evolve relative resistance to angiostatic therapy will be selectively susceptible to attack by the iron-loading/artemisinin strategy.


Asunto(s)
Inhibidores de la Angiogénesis/farmacología , Factores de Transcripción/metabolismo , Artemisininas/farmacología , Resistencia a Antineoplásicos , Humanos , Subunidad alfa del Factor 1 Inducible por Hipoxia , Hierro/metabolismo , Modelos Teóricos , Mutación , Oxígeno/metabolismo , Receptores de Transferrina/metabolismo , Sesquiterpenos/farmacología , Regulación hacia Arriba
19.
Med Hypotheses ; 61(3): 323-34, 2003 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-12944100

RESUMEN

IGF-I acts on vascular endothelium to activate nitric oxide synthase, thereby promoting vascular health; there is reason to believe that this protection is especially crucial to the cerebral vasculature, helping to ward off thrombotic strokes. IGF-I may also promote the structural integrity of cerebral arteries, thereby offering protection from hemorrhagic stroke. These considerations may help to explain why tallness is associated with low stroke risk, whereas growth hormone deficiency increases stroke risk--and why age-adjusted stroke mortality has been exceptionally high in rural Asians eating quasi-vegan diets, but has been declining steadily in Asia as diets have become progressively higher in animal products. There is good reason to suspect that low-fat vegan diets tend to down-regulate systemic IGF-I activity; this effect would be expected to increase stroke risk in vegans. Furthermore, epidemiology suggests that low serum cholesterol, and possibly also a low dietary intake of saturated fat--both characteristic of those adopting low-fat vegan diets--may also increase stroke risk. Vegans are thus well advised to adopt practical countermeasures to minimize stroke risk--the most definitive of which may be salt restriction. A high potassium intake, aerobic exercise training, whole grains, moderate alcohol consumption, low-dose aspirin, statin or policosanol therapy, green tea, and supplementation with fish oil, taurine, arginine, and B vitamins--as well as pharmacotherapy of hypertension if warranted--are other practical measures for lowering stroke risk. Although low-fat vegan diets may markedly reduce risk for coronary disease, diabetes, and many common types of cancer, an increased risk for stroke may represent an 'Achilles heel'. Nonetheless, vegans have the potential to achieve a truly exceptional 'healthspan' if they face this problem forthrightly by restricting salt intake and taking other practical measures that promote cerebrovascular health.


Asunto(s)
Dieta Vegetariana/efectos adversos , Factor I del Crecimiento Similar a la Insulina/metabolismo , Accidente Cerebrovascular/prevención & control , Animales , Humanos , Factores de Riesgo
20.
Melanoma Res ; 13(4): 379-87, 2003 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-12883364

RESUMEN

The aim of this study was to determine whether epidermal hyperplasia overlying cutaneous human melanoma is associated with increased tumour angiogenesis, tumour growth and the potential for metastasis. Forty-two surgical specimens of cutaneous human melanoma of different depths, each containing epidermis present in the tumour-free margin, were analysed by immunohistochemistry for the expression of the pro-angiogenic molecules basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF) and interleukin-8 (IL-8) and the anti-angiogenic molecule interferon-beta (IFN-beta). The epidermis overlying intermediate and thick (1.0-10.0 mm), but not thin (0.5-1.0 mm), melanoma specimens was hyperplastic. Although the expression level of bFGF, VEGF and IL-8 in the epidermis directly overlying the tumour was similar to that in the distant epidermis, the expression of IFN-beta was significantly decreased in keratinocytes overlying intermediate and thick, but not thin, melanomas. The microvessel density was also increased in intermediate and thick specimens. Human melanoma cells were injected subcutaneously into nude mice. The resulting tumours were used to determine the association between overlying epidermal hyperplasia and neoplastic angiogenesis. Similar to human autochthonous melanomas, epidermal hyperplasia was found only over lesions produced by metastatic cells. Although there was no change in the expression of the pro-angiogenic molecules, the expression of IFN-beta was significantly decreased in the hyperplastic epidermis. Conditioned medium collected from cultures of the metastatic cell line induced in vitro proliferation of mouse keratinocytes, whereas conditioned medium collected from cultures of the non-metastatic cell line did not. Collectively, the data demonstrate that metastatic melanoma cells induce keratinocyte proliferation, leading to decreased expression of the negative regulator of angiogenesis, IFN-beta, and hence to increased angiogenesis.


Asunto(s)
Epidermis/patología , Melanoma/irrigación sanguínea , Melanoma/patología , Neovascularización Patológica/patología , Neoplasias Cutáneas/irrigación sanguínea , Neoplasias Cutáneas/patología , Animales , Epidermis/metabolismo , Sustancias de Crecimiento/metabolismo , Humanos , Hiperplasia , Inmunohistoquímica , Interferón beta/metabolismo , Masculino , Melanoma/metabolismo , Ratones , Ratones Endogámicos BALB C , Ratones Desnudos , Neovascularización Patológica/metabolismo , Neoplasias Cutáneas/metabolismo
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