RESUMEN
The literature on the content and stability of vitamin C (ascorbic acid, AA) in citrus juices in relation to industrial practices is reviewed. The role of vitamin C from citrus juices in human diet is also reviewed. Citrus fruits and juices are rich in several types of bioactive compounds. Their antioxidant activity and related benefits derive not only from vitamin C but also from other phytochemicals, mainly flavonoids. During juice processing, temperature and oxygen are the main factors responsible for vitamin C losses. Non-thermal processed juices retain higher levels of vitamin C, but economic factors apparently delay the use of such methods in the citrus industry. Regarding packing material, vitamin C in fruit juice is quite stable when stored in metal or glass containers, whereas juice stored in plastic bottles has a much shorter shelf-life. The limiting step for vitamin C absorption in humans is transcellular active transport across the intestinal wall where AA may be oxidized to dehydroascorbic acid (DHAA), which is easily transported across the cell membrane and immediately reduced back to AA by two major pathways. AA bioavailability in the presence of flavonoids has yielded controversial results. Whereas flavonoids seem to inhibit intestinal absorption of AA, some studies have shown that AA in citrus extract was more available than synthetic ascorbic acid alone. DHAA is reported to possess equivalent biological activity to AA, so recent studies often consider the vitamin C activity in the diet as the sum of AA plus DHAA. However, this claimed equivalence should be carefully reexamined. Humans are one of the few species lacking the enzyme (L-gulonolactone oxidase, GLO) to convert glucose to vitamin C. It has been suggested that this is due to a mutation that provided a survival advantage to early primates, since GLO produces toxic H2O2. Furthermore, the high concentration of AA (and DHAA) in neural tissues could have been the key factor that caused primates (vertebrates with relative big brain) to lose the capacity to synthesize vitamin C. Oxidative damage has many pathological implications in human health, and AA may play a central role in maintaining the metabolic antioxidant response. The abundance of citrus juices in the Mediterranean diet may provide the main dietary source for natural vitamin C.
Asunto(s)
Antioxidantes/metabolismo , Ácido Ascórbico/metabolismo , Bebidas , Citrus/química , Animales , Antioxidantes/química , Antioxidantes/farmacocinética , Antioxidantes/fisiología , Ácido Ascórbico/química , Ácido Ascórbico/farmacocinética , Ácido Ascórbico/fisiología , Carotenoides/metabolismo , Colágeno/biosíntesis , Dieta , Flavonoides/metabolismo , Manipulación de Alimentos , Humanos , Limoninas/metabolismo , Política Nutricional , Sustancias Protectoras/química , Sustancias Protectoras/metabolismo , Sustancias Protectoras/farmacocinética , Ratas , Escorbuto/tratamiento farmacológicoRESUMEN
INTRODUCTION: Orthopedic implant infections are significant because of their morbidity, a tendency to serious relapses and an elevated health cost. OBJECTIVES: To study prognostic factors and the influence of long-term antibiotic treatment on the evolution of orthopedic implant infections. METHODS: This prospective study was performed in 110 patients with orthopedic implant infections. Clinical, analytical, and microbiological studies, as well as gammagraphy with Tc, Ga and labeled leukocytes, were performed in all patients. Controls were carried out at 7, 15 and 30 days after starting treatment, every 3 months thereafter until the end of treatment, and every 6 months thereafter up to one year after stopping treatment. Initial antibiotic treatment was prescribed according to the epidemiological characteristic of the type of infection and was modified according to the microorganism isolated. Duration of treatment was established by patient and implant characteristics, severity of infection and evolution of the process, and it was adjusted to criteria of cure, failure and relapse. RESULTS: Among the 110 cases, 63 were women and 37 men, with a mean age of 59.6 years (range 18-79 years). Implants included 72 joint prostheses (42 knee, 29 hip and 1 shoulder) and 38 bone implants. Microbiological documentation was obtained in 60%; among these, 60.6% were gram-positive cocci, with a predominance of staphylococci, 33.3% were gram-negative bacilli and 6.1% were anaerobic microorganims. Prognostic factors significantly associated with failure or relapse included previous joint surgery, previous hospital stay longer than 15 days, diabetes, microbiological isolation and treatment with cefuroxim plus rifampicin. Mean treatment duration was 9.8 months (range 2-17 months). Antibiotic treatment consisted of the following: 61 cases received fluorquinolones or cotrimoxazole plus rifampicin, 29 received cefuroxime-axetil plus rifampicin and the remaining 20 received monotherapy. Among 110 cases, 91 cured (83%). Treatment failures or relapses were observed in 19 (17%) patients; 26.7% of the latter were related to the implants. Tolerance to long-term antibiotic treatment was good.Conclusion. Long-term antibiotic treatment lasting a mean of 9.8 months had a positive influence on the evolution of orthopedic implant infections.
Asunto(s)
Antibacterianos , Quimioterapia Combinada/uso terapéutico , Prótesis Articulares , Infecciones Relacionadas con Prótesis/epidemiología , Adulto , Anciano , Quimioterapia Combinada/administración & dosificación , Femenino , Estudios de Seguimiento , Humanos , Masculino , Persona de Mediana Edad , Osteomielitis/epidemiología , Pronóstico , Estudios Prospectivos , Infecciones Relacionadas con Prótesis/tratamiento farmacológico , RecurrenciaRESUMEN
INTRODUCCIÓN. Las infecciones de los implantes osteoarticulares (IOA) son de gran importancia por su morbilidad, tendencia a mayores recidivas y elevado coste sanitario. OBJETIVOS. Estudio de los factores pronósticos y la influencia del tratamiento antibiótico prolongado en su evolución. MÉTODOS. Se han estudiado de forma prospectiva 110 pacientes diagnosticados de infecciones de implantes osteoarticulares. En todos los pacientes se realizaron estudios clínicos, analíticos, microbiológicos y gammagráficos con tecnecio, galio y leucocitos marcados, efectuándose controles a los 7, 15, 30 días del inicio y después cada 3 meses hasta el final del tratamiento y después cada 6 meses hasta un año después de su suspensión. El tratamiento antibiótico inicial se realizó de acuerdo con las características epidemiológicas según el tipo de infección, modificándolo en relación con los microorganismos aislados. La duración del tratamiento se estableció en función del tipo de paciente, prótesis, gravedad de la infección y curso evolutivo. Su evolución se ajustó a los criterios de curación, fallo y recidiva. RESULTADOS. De los 110 casos, 63 eran mujeres y 37 varones con una edad media de 59,6 años (límites, 18 y 79 años). De ellos, 72 correspondían a prótesis articulares (42 de rodilla, 29 de cadera y uno de hombro) y 38 a implantes óseos. El 60 por ciento de los episodios se documentaron microbiológicamente. El 60,6 por ciento estuvieron causados por cocos grampositivos con predominio del género estafilococo, el 33,3 por ciento por bacilos gramnegativos y el 6,1 por ciento por anaerobios. Como factores pronósticos asociados a fracasos o recidivas se encontró de forma significativa la cirugía articular previa, una estancia hospitalaria previa superior a 15 días, la presencia de diabetes, la documentación microbiológica y el tratamiento antibiótico con cefuroxima más rifampicina. La duración media del tratamiento fue de 9,8 meses (límites, 2 y 17 meses). El tratamiento antibiótico fue el siguiente: 61 pacientes recibieron fluorquinolonas o cotrimoxazol más rifampicina y 29 cefuroxima-axetilo más rifampicina. Los restantes 20 pacientes recibieron un solo antibiótico. De los 110 casos, 91 (83 por ciento) evolucionaron hacia la curación. Los fracasos o las recidivas se observaron en 19 enfermos (17 por ciento del total de IOA y 26,7 por ciento en relación de las prótesis articulares) que requirieron la retirada de la prótesis. La tolerancia al tratamiento antibiótico prolongado fue buena. CONCLUSIÓN. El tratamiento antibiótico prolongado, con una duración media de 9,8 meses, influye positivamente en la mejor evolución de los IOA (AU)