RESUMO
Vitamin C is an essential factor for neuronal function and survival, existing in two redox states, ascorbic acid (AA), and its oxidized form, dehydroascorbic acid (DHA). Here, we show uptake of both AA and DHA by primary cultures of rat brain cortical neurons. Moreover, we show that most intracellular AA was rapidly oxidized to DHA. Intracellular DHA induced a rapid and dramatic decrease in reduced glutathione that was immediately followed by a spontaneous recovery. This transient decrease in glutathione oxidation was preceded by an increase in the rate of glucose oxidation through the pentose phosphate pathway (PPP), and a concomitant decrease in glucose oxidation through glycolysis. DHA stimulated the activity of glucose-6-phosphate dehydrogenase, the rate-limiting enzyme of the PPP. Furthermore, we found that DHA stimulated the rate of lactate uptake by neurons in a time- and dose-dependent manner. Thus, DHA is a novel modulator of neuronal energy metabolism by facilitating the utilization of glucose through the PPP for antioxidant purposes.
Assuntos
Ácido Desidroascórbico/farmacologia , Metabolismo Energético/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Animais , Ácido Ascórbico/metabolismo , Ácido Ascórbico/farmacologia , Transporte Biológico , Células Cultivadas , Ácido Desidroascórbico/metabolismo , Glucose/metabolismo , Transportador de Glucose Tipo 1/metabolismo , Transportador de Glucose Tipo 3/metabolismo , Glucosefosfato Desidrogenase/metabolismo , Glutationa/metabolismo , Glicólise/efeitos dos fármacos , Lactatos/metabolismo , Modelos Neurológicos , Neurônios/metabolismo , Oxirredução , Via de Pentose Fosfato/efeitos dos fármacos , Cultura Primária de Células , Ratos , Ratos Sprague-Dawley , Transportadores de Sódio Acoplados à Vitamina C/metabolismoAssuntos
Laparoscopia , Gravidez Ectópica/cirurgia , Adulto , Feminino , Humanos , Gravidez , Gravidez Tubária/cirurgia , Resultado do TratamentoRESUMO
STUDY OBJECTIVE: Previous cesarean delivery scar (PCDS) defect has been described as a cause of intermenstrual bleeding in women with no other uterine pathology except for a pouch on the anterior uterine segment at the site of the cesarean scar. The objective of this study was to assess the effectiveness of hysteroscopic surgery to correct this anatomic defect and eliminate the bleeding disturbance in a group of women with this symptom. DESIGN: Retrospective study (Canadian Task Force classification XX). SETTING: Private hospital, department of obstetrics and gynecology. PATIENTS: Twenty-four women, age 29-41 years, who reported intermenstrual bleeding, especially postmenstrual spotting, with no other gynecologic pathology except for the presence of a PCDS defect. Diagnosis was established with transvaginal ultrasound, when a fluid-filled, triangular defect was seen in the anterior uterine isthmus, in relation to the cesarean section scar. INTERVENTION: Hysteroscopic resection of fibrotic tissue that overhangs underneath the triangular pouch, facilitating blood drainage through the cervix and fulguration of endometrial glands and/or dilated blood vessels. MEASUREMENTS AND MAIN RESULTS: The mean number of previous cesarean-section deliveries was 2.75. Postoperative follow-up was 24 months in 21 patients and at least 14 months in the other 3 patients. Eleven of these patients with the desire to become pregnant were unable to conceive after trying for a period of at least 2 years before hysteroscopy. Infertility work-up in the 11 patients revealed 9 with unknown infertility, 1 with male infertility, and 1 with failed tubal reversal surgery. Nine of them became pregnant between 14- and 24-months of follow-up. Eighty-four percent of patients (20/24) remained asymptomatic (without bleeding disturbances) after surgery. CONCLUSION: Previous cesarean delivery scar defect may be the cause of intermenstrual bleeding, and it is possible that it also may impair fertility, but it can be successfully treated by hysteroscopic surgery.
Assuntos
Cesárea , Cicatriz/complicações , Hemorragia Uterina/etiologia , Hemorragia Uterina/cirurgia , Adulto , Cicatriz/cirurgia , Feminino , Seguimentos , Humanos , Histeroscopia , Infertilidade Feminina/etiologia , Infertilidade Feminina/cirurgia , Gravidez , Estudos Retrospectivos , Fatores de TempoRESUMO
OBJECTIVE: We sought (1) to describe an anatomic defect of the uterine cavity in the anterior isthmus diagnosed by transvaginal sonography in a group of premenopausal women with previous cesarean deliveries, (2) to establish whether there is an association between the presence of the pouch and a bleeding disturbance, and (3) to compare the diagnostic efficacy of transvaginal sonography versus hysteroscopy for the detection of this defect. METHODS: We performed a retrospective study of 92 premenopausal women with histories of at least 1 cesarean delivery. Age, number of previous cesarean deliveries, time elapsed between last cesarean delivery and first consultation, and total area of the pouch were recorded in groups of women with and without abnormal bleeding. Hysteroscopy was also performed in 43.8% of the patients who had abnormal bleeding. RESULTS: In all women, transvaginal sonography revealed the presence of a pouch on the anterior uterine segment at the site of the expected previous cesarean delivery scar. Hysteroscopy showed 100% correlation with transvaginal sonography in detection of this pouch. CONCLUSIONS: The high correlation between bleeding disturbances and the presence of a pouch, in the absence of other pathologic entities, suggests this anatomic defect as the possible cause, especially in view of the fact that women who had heavier and longer bleeding episodes tended to have a larger pouch. Transvaginal sonography is a very simple, noninvasive, low-cost examination that should be considered as the first choice for screening, because it highly correlates (100%) with hysteroscopy in the diagnosis of this defect and may help rule out other causes.